JP3356174B2 - TRANSMISSION SCREEN AND REAR PROJECTION DISPLAY DEVICE HAVING THE SAME - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmissive screen and a rear projection type image display device using the same.

[0002]

2. Description of the Related Art A rear projection type such as a rear projection television receiver which enlarges an image displayed on a projection type cathode ray tube or a liquid crystal display device as a small image source by a projection lens and projects the image on a transmission type screen. 2. Description of the Related Art Image display apparatuses have been remarkably improved in image quality in recent years and can enjoy a powerful sense of realism due to a large screen.

In this rear projection type image display device, when a projection type cathode ray tube is used as an image generation source, red, green, and blue have generally been used in order to sufficiently increase the brightness of a screen on a transmission type screen. Combining a CRT and a projection lens for each of the three primary colors,
An image of three primary colors is synthesized on a transmission screen.

Conventionally, as a transmission screen used for a rear projection type image display apparatus having this configuration, for example,
As described in JP-A-58-59436, a two-screen transmission screen combining a Fresnel lens sheet and a lenticular lens sheet has been proposed. However, this proposed example does not disclose specific technical means for realizing diffusion of image light in the vertical direction of the screen screen.

On the other hand, in order to realize diffusion of image light in the vertical direction of the screen screen, for example, Japanese Patent Application Laid-Open No.
-117226 or JP-A-58-1920.
No. 22, as described in Japanese Patent Publication No.
There has been proposed a two-piece transmission screen combining a lenticular lens sheet in which a light diffusing material for scattering light is dispersed as fine particles inside.

Hereinafter, this conventional technique will be described.

FIG. 106 is a perspective view showing a main part of the above-mentioned conventional transmission screen.

In FIG. 106, 1 is a transmissive screen, 10 is a Fresnel lens sheet arranged on the image source (CRT screen) side, and 30 'is a lenticular lens sheet arranged on the image viewing side. The base material of each of the Fresnel lens sheet 10 and the lenticular lens sheet 30 'is made of a transparent thermoplastic resin. this house,
In the base material of the lenticular lens sheet 30 ', the light diffusing material 6 for scattering light is dispersed as fine particles. The fine particles of the light diffusing material 6 have a refractive index different from the refractive index of the base material 30B of the lenticular lens sheet 30 ', and scatter light vertically and horizontally by refraction or reflection. The light diffusing material may be dispersed as fine particles in the base material 30B of the lenticular lens sheet 30 ', or may be laminated as a light diffusing layer on the surface of the lenticular lens sheet 30'.

Reference numerals 11 and 12 designate Fresnel lens sheets 10
Are a light incident surface and a light exit surface, respectively.
Is a flat surface, and the light emitting surface 12 is a Fresnel convex lens shape.

Reference numeral 31 'denotes a light incident surface of the lenticular lens sheet 30', which has a shape in which a plurality of first vertically long lenticular lenses having a longitudinal direction perpendicular to the screen screen are arranged in the horizontal direction of the screen screen. .
Reference numeral 32 'denotes a light exit surface of the lenticular lens sheet 30'. The light entrance surface 31 'is substantially opposed to the first vertically elongated lenticular lens, and a plurality of second vertically elongated lenticular lenses having the same shape are arranged. Between the adjacent lenticular lenses, a convex projection 32P
Are provided, and a light absorption band (black stripe) 33 is laminated on the convex protrusion 32P.

In the above-mentioned conventional transmission type screen, the luminous flux emitted from each point of the display image on the projection type cathode ray tube surface passes through a projection lens (neither is shown).
The light enters the light incident surface 11 of the Fresnel lens sheet 10.
This incident light beam is converted into a substantially parallel light beam by the Fresnel lens on the light exit surface 12 of the Fresnel lens sheet 10,
The light enters the lenticular lens sheet 30 '.

The light beam incident on the lenticular lens sheet 30 'is directed to a focal point near the second longitudinal lenticular lens surface on the light exit surface 32' by the first longitudinal lenticular lens on the light incident surface 31 ', and from that focal point. The light is diffused in the horizontal direction of the screen screen and emitted to the image viewing side while being diffused in the vertical and horizontal directions of the screen screen by the light diffusing material 6 dispersed as fine particles in the base material. That is, the diffusion of the incident light beam in the horizontal direction of the screen is mainly performed depending on the shapes of the first and second vertically long lenticular lenses, and the diffusion in the vertical direction of the screen is performed only by the action of the light diffusing material 6.

On the other hand, for example, Japanese Patent Application Laid-Open No. 58-93043
As described in Japanese Patent Application Laid-Open Publication No. H10-209, the diffusion of image light in the vertical direction of the screen screen is performed by a light diffusing material dispersed as fine particles inside a lenticular lens sheet and a lens function of a lenticular lens provided on one surface of a Fresnel lens sheet. A two-screen transmission screen has been proposed.

Hereinafter, this conventional technique will be described.

FIG. 107 is a perspective view showing a main part of the above-mentioned conventional transmission screen.

In FIG. 107, the light incident surface 11 of the Fresnel lens sheet 10 has a shape in which a plurality of horizontally long lenticular lenses each composed of a part of a cylinder whose longitudinal direction is the screen screen horizontal direction are arranged in the screen screen vertical direction. . Other configurations are the same as those of the transmission screen of FIG.

In the transmission screen having the structure shown in FIG. 107,
Since the horizontal lenticular lens is provided on the light incident surface 11 of the Fresnel lens sheet 10, the incident luminous flux is slightly imparted with a diffusion characteristic in the vertical direction of the screen by the horizontal lenticular lens. Thereafter, the light diffusing material 6 in the base material of the lenticular lens sheet 30 ′ further imparts a diffusion characteristic in the screen screen vertical direction. The diffusion of the incident light beam in the horizontal direction of the screen screen is performed mainly depending on the shapes of the first and second vertically long lenticular lenses, as in the case of FIG.

Here, the horizontally long lenticular lens on the light incident surface 11 of the Fresnel lens sheet 10 will be described in more detail.

FIG. 108 shows the transmission screen 1 shown in FIG.
108 is a sectional view showing a vertical section of the Fresnel lens sheet 10 of FIG. 108, and in FIG. 108, reference numeral 140 denotes an incident light beam.

In FIG. 108, on the light incident surface 11 of the Fresnel lens sheet 10, as described above, a plurality of horizontally long lenticular lenses each composed of a part of a cylinder whose longitudinal direction is the screen screen horizontal direction are arranged in the screen screen vertical direction. It has a shape. The pitch of the horizontally long lenticular lens is set smaller than the pitch of the scanning lines of the projected image or the pitch of the pixels, and furthermore, the moire with the pitch of the scanning lines of the projected image, and the fresnel lens sheet 2 at the upper and lower parts of the screen. Moire with the pitch of the annular zone of the Fresnel convex lens is determined so as not to be conspicuous.

More specifically, the pitch of the horizontally long lenticular lens is set to the first, lenticular lens sheet 30 '.
The pitch is set sufficiently smaller than the pitch of the second vertically long lenticular lens, and the pitch of the scanning line of the projected image and the pitch of the horizontally long lenticular lens are not set to a simple integer ratio.

For example, when the screen size of the transmission screen is 800 mm in the horizontal direction of the screen screen, 600 mm in the vertical direction of the screen screen, and the pitch in the horizontal direction of the screen screen is 0.78 mm, 480 lines are displayed on the screen screen. Assuming that horizontal scanning lines are displayed, the pitch of the scanning lines is 1.25 mm. Therefore, with respect to the pitch of the scanning lines, the pitch of the ring zone of the Fresnel convex lens is about 0.1 to 0.12 mm, and the pitch of the horizontally long lenticular lens is about 0.08 to 0.1 mm. Each is often chosen.

On the other hand, when the incident light beam 140 is incident from the horizontally long lenticular lens of the light incident surface 11, even if it is the same scanning line or the same pixel, the incident angle differs depending on the incident position. Is diffused in the vertical direction of the screen screen. In addition, if the radius of curvature of the above-mentioned horizontally long lenticular lens is reduced, the incident angle of the incident light beam 140 is increased, and the light beam is diffused over a wider angle range to increase the directivity, thereby increasing the so-called vertical viewing angle.

Next, the lenticular lens sheet 30 '
The vertically elongated lenticular lens of the light incident surface 31 'and the light exit surface 32' will be described in more detail.

FIGS. 109 and 110 are sectional views showing a horizontal section of the lenticular lens sheet 30 'of the transmissive screen 1 of FIG. 106 or FIG.
9. In FIG. 110, reference numeral 140 denotes an incident light beam.

In FIGS. 109 and 110, the lens surface of the first vertically elongated lenticular lens on the light incident surface 31 'is a part of an elliptical cylindrical surface, and the ellipse is in the thickness direction of the lenticular lens sheet (1 in the drawings). , L ′) in the major axis direction, and one of the two focal points of the ellipse is the base 30B ′
And the other focal point is located near the light exit surface 32 '. Also, the eccentricity e of the ellipse
Is selected to be approximately the reciprocal of the refractive index n of the substrate. In FIGS. 109 and 110, the refractive index n is 1.517.
The distance (distance on the optical axis) between the light incident surface 31 'and the light exit surface 32' is drawn as 0.86 mm.

By adopting such a configuration, FIG.
As shown in FIG. 9, all the green light rays incident on the first vertically long lenticular lens in parallel to the major axis of the ellipse are emitted from the light exit surface 3.
It converges to a focal point near 2 ', and is diffused from this focal point in the horizontal direction of the screen. Also, as shown in FIG.
The red and blue light rays incident on the first vertically elongated lenticular lens at an angle with respect to the major axis of the ellipse are all converged to the vicinity of the focal point near the light exit surface 32 ', and from this point the screen screen is moved in the horizontal direction. It is spread to. FIG. 110 is a ray tracing diagram in the case where the obliquely incident light beam is incident at a concentration angle of 10 degrees with respect to the major axis of the ellipse.

The lens surface of the second vertically long lenticular lens on the light emitting surface 32 'is an elliptical cylindrical surface substantially symmetrical to the elliptical cylindrical surface of the first vertically elongated lenticular lens on the surface of the light emitting surface 32'. . The second vertically long lenticular lens has a function of making the directional characteristics of the outgoing light beams of these colors substantially parallel to the incoming light beams of red, green, and blue.

Next, the lenticular lens sheet 30 '
The light diffusing material 6 dispersed in the base material will be described in more detail.

FIG. 111 is a cross-sectional view showing a cross section of the lenticular lens sheet 30 'in the transmissive screen 1 shown in FIG. 106 or 107. FIG. 111 (a) shows a portion of one lenticular lens on the light emitting surface 32'. , And FIG. 111 (b) shows a horizontal section.

In FIGS. 111A and 111B, the base material 30B 'of the lenticular lens sheet 30' is shown.
Inside, the light diffusing material 6 is dispersed as fine particles as described above, so that the incident light 140
After entering from 1 ', the light advances while diffusing in the horizontal and vertical directions of the screen screen, and exits from the light exit surface 32' to the image viewing side. If the amount of the light diffusing material is increased, the light is diffused over a wider angle range, the directional characteristics are widened, and the viewing angle is increased.

[0032]

There are several problems to be solved in the above-mentioned prior art transmission screen. Hereinafter, this problem will be described.

The first problem is to increase the range of the horizontal viewing angle and the vertical viewing angle.

FIG. 112 is an explanatory diagram for explaining a general horizontal viewing angle and a vertical viewing angle.

The horizontal viewing angle and the vertical viewing angle when facing the screen are each 0 degrees.

[0036] changing the forceps position the screen horizontally, by measuring the image brightness B _alpha on the screen from the direction of the horizontal view viewing angle alpha [degrees] with respect to the screen, the screen luminance B ₀ in the case of directly opposite the screen (Relative luminance) H =
B _α / B ₀ is determined. Similarly, the vertical direction of the screen, the proportion of by measuring the image brightness B _beta on the screen from a direction perpendicular view viewing angle beta [degrees] with respect to the screen, the screen brightness B ₀ in the case of directly opposite the screen ( (Relative luminance) H = _Bβ / _B0 is obtained.

When the relative luminance H becomes smaller than a certain threshold value, the image becomes almost invisible. Hereinafter, the ranges of the horizontal viewing angle α and the vertical viewing angle β at which an image can be viewed are referred to as a horizontal viewing range and a vertical viewing range, respectively. The horizontal viewing angle α and the vertical viewing angle β at which the relative luminance H = B _α / B ₀ and H = B _β / B ₀ are 50% are hereinafter referred to as a horizontal viewing angle and a vertical viewing angle, respectively.

FIG. 113 is a characteristic diagram showing the directivity characteristics of green image light obtained in the transmission screen according to the prior art. The solid line indicates the substrate 30B 'of the lenticular lens sheet 30' in the transmission screen 1 of FIG.
107, the directional characteristics in the horizontal direction of the screen when the refractive index is 1.50, and the broken lines show the directional characteristics in the vertical direction obtained in the transmission screen 1 of FIG.

As shown in FIG. 113, in the transmission type screen according to the prior art, an image on the screen cannot be viewed at a position where the horizontal viewing angle α exceeds ± 47 degrees. Also, the image on the screen cannot be viewed even at a position where the vertical viewing angle β exceeds ± 25 degrees. Further, the relative luminance H
= B _β / B ₀ is 50%, and the vertical viewing angle is very narrow at about ± 9 degrees.

FIG. 114 is a characteristic diagram showing the directivity in the vertical direction of the horizontally long lenticular lens of the Fresnel lens sheet 10 of the transmission screen 1 according to the prior art.

As shown in FIG. 114, in the transmission screen according to the prior art, by setting the radius of curvature of the horizontally long lenticular lens of the Fresnel lens sheet 10 to about 0.3 mm, a vertical viewing range of about ± 4 degrees is obtained. ing.
By combining this horizontally long lenticular lens with the light diffusing material in the base material of the lenticular lens sheet 30 ',
As described above, the transmission screen has a vertical viewing range of ± 25 degrees as a whole.

In the conventional transmission screen,
By adopting a configuration in which the center of the Fresnel convex lens of the Fresnel lens sheet 10 is shifted vertically from the center of the screen, the directional characteristics may be slightly shifted from the vertically symmetric characteristics.

FIG. 115 shows that the center of the Fresnel convex lens of the Fresnel lens sheet 10 is 50 mm upward from the center of the screen.
FIG. 9 is a characteristic diagram showing a directional characteristic in a vertical direction of a screen screen in a case where the maximum luminance is obtained in a direction approximately 5 degrees above the front direction with a slight shift.

The directional characteristics of the transmissive screen are preferably wider in the horizontal direction and the vertical direction than the directional characteristics of the transmissive screen according to the prior art, and particularly, the directional characteristics having a wide bottom are desirable.

FIG. 116 is a characteristic diagram showing an example of a desirable directional characteristic in the transmission type screen. The directional characteristic has a wide bottom so that both the horizontal viewing range and the vertical viewing range are about ± 70 degrees. I have.

In order to improve the directional characteristics of the above-mentioned conventional transmission screen, the directional characteristics in the vertical direction of the screen are further expanded to increase the vertical viewing angle, and the base material of the lenticular lens sheet 30 'is used. It is sufficient to increase the amount of the light diffusing material 6 in the inside or to reduce the radius of curvature of the horizontally long lenticular lens on the light incident surface 11 of the Fresnel lens sheet 10.

However, in the conventional transmission screen, if the amount of the light diffusing material 6 in the base material of the lenticular lens sheet 30 'is increased, the following problems occur.

FIG. 117 is a schematic sectional view showing the manner in which the incident light beam is diffused in the vertical direction of the screen screen in the vertical section of the transmission screen 1 of FIG. 107.
FIG. 8 is a schematic sectional view showing a state in which an incident light beam is diffused in the horizontal direction of the screen screen in the horizontal section of the transmission screen 1 of FIG. In FIGS. 117 and 118, reference numeral 140 denotes an incident light beam.

As shown in FIGS. 117 and 118, the incident light beam 140 incident on the Fresnel lens sheet 10 is refracted by the shape of the horizontally long lenticular lens on the light incident surface 11 and diffused in the vertical direction of the screen screen, and then lenticular. Since the light enters the lens sheet 30 ′ and is further diffused by the light diffusing material 6 in the base material, the width d of the light flux when viewed from the image viewing side becomes larger than the width of the incident light flux 140, and the light is emitted. The scanning line width or the pixel size on the surface 32 'increases, and as a result, the focus characteristics of the image deteriorate.

At this time, the lenticular lens sheet 3 is used in order to widen the directivity of the screen screen in the vertical direction.
When the amount of the light diffusing material 6 in the base material of 0 'is increased, the scanning line width or the pixel size on the light emitting surface 32' of the lenticular lens sheet 30 'is further increased, and the focus characteristic of the image is further reduced. .

As shown in FIGS. 117 and 118, in the lenticular lens sheet 30 ', the incident light beam 140 is not only diffused by the light diffusing material 6 in the base material but also scattered. Is reflected again on the light incident surface 31 'side, becomes stray light in the lenticular lens sheet 30', or the light absorption band 3
3, the light does not reach the focal point near the light exit surface 32 'and does not exit from the light exit surface 32', and the brightness of the screen screen viewed from the image viewing side decreases.
This decrease in brightness is more remarkable as the light diffusing material 6 increases.

Of the incident light beam 140, the light that has been scattered by the light diffusing material 6 and has become stray light as described above travels in the projection optical system as unnecessary reflected light, and a part of the light eventually ends up. The light reaches the screen screen (that is, the light exit surface 32 'of the lenticular lens sheet 30'), and the image contrast is reduced. Further, about half of the external light such as illumination light is absorbed by the light absorption band 33 provided on the light exit surface 32 'of the lenticular lens sheet 30', but the second longitudinal lenticular of the light exit surface 32 ' External light that has entered the lens is diffusely reflected by the light diffusing material 6, and similarly causes a reduction in image contrast. Such a decrease in contrast cannot be overlooked due to an increase in the amount of the light diffusing material 6.

On the other hand, in a conventional transmission screen,
When the radius of curvature of the horizontally long lenticular lens on the light incident surface 11 of the Fresnel lens sheet 10 is reduced, the following problem occurs.

As described above, as shown in FIGS. 117 and 118, the incident light beam 140 incident on the Fresnel lens sheet 10 is refracted by the shape of the horizontally long lenticular lens on the light incident surface 11 and diffuses in the direction perpendicular to the screen of the screen. After that, the light enters the lenticular lens sheet 30 ′ and is further diffused by the light diffusing material 6 in the base material. Therefore, when viewed from the image viewing side, the width d of the light flux is equal to the incident light flux 1.
When the width is larger than the width of 40, the scanning line width or the pixel size on the light emitting surface 32 'is increased, and as a result, the focus characteristic of the image is reduced.

At this time, if the radius of curvature of the horizontally long lenticular lens on the light incident surface 11 of the Fresnel lens sheet 10 is reduced in order to widen the directivity characteristics in the vertical direction of the screen screen, the light exit surface 32 'of the lenticular lens sheet 30' is reduced. The scanning line width or the pixel size becomes larger and the focus characteristic of the image further deteriorates. For this reason, in the prior art, the radius of curvature of the horizontally long lenticular lens on the light incident surface 11 of the Fresnel lens sheet 10 had to be practically at least about 0.3 mm.

In a conventional transmission type screen, when the radius of curvature of the horizontally long lenticular lens on the light incident surface 11 of the Fresnel lens sheet 10 is 0.3 mm, the directivity characteristics of the horizontally long lenticular lens alone in the screen screen vertical direction are as follows. , As described above with reference to FIG.

As shown in FIG. 114, the above-mentioned horizontally long lenticular lens alone can obtain a vertical viewing angle of about ± 4 degrees.

Therefore, as described above, in the conventional transmissive screen, the directivity in the vertical direction of the screen cannot be expanded so that there is no trade-off in the focus characteristic, brightness, and contrast of the image. was there.

The second problem is to reduce the color shift.

The color shift means that when the projection light flux of each color of red, green, and blue is diffused in the horizontal direction of the screen by the lenticular lens sheet 30 ', the directivity of each color is slightly different. A phenomenon in which the balance of the three primary colors of red, green, and blue changes according to the viewing angle α, and the color of the image changes. Details will be described later.

This color shift is based on the relative value of the luminance R of red light and the luminance B of blue light (the brightest luminance Rm, respectively).
ax, Bmax) (relative value based on Bmax) as a logarithm, and is evaluated by the following equation (1).

[0062]

## EQU1 ## 10 × log ｛(R / Rmax) / (B / Bm
ax)｝ This color shift is expressed in units of dB, and the closer to 0, the better the characteristics. For example, the ratio of the relative luminance of red and blue is 1: 1
Is 0 dB, and 2: 1 is about 3 dB.

As described above, the lens surface of the second vertically long lenticular lens on the light exit surface 32 'of the lenticular lens sheet 30' directs the emitted light beams of these colors with respect to the incident light beams of red, green and blue. It has a function of making the characteristics substantially parallel to each other, and although the color shift is somewhat reduced by this function, a sufficient effect is not always obtained.

FIG. 119 shows the red, green, and red colors obtained by the lenticular lens sheet 30 'shown in FIGS.
FIG. 4 is a characteristic diagram illustrating directivity characteristics of blue image light, showing a case where obliquely incident light beams of red and blue enter a major axis of an ellipse at a concentration angle of 10 degrees.

In the example of FIG. 119, a 1.8 dB color shift occurs at a viewing angle of 30 degrees.

For red light and blue light, there is a so-called cutoff in which the luminance sharply decreases at viewing angles outside 45 degrees and -45 degrees, respectively. For green light, a similar cutoff occurs around ± 50 degrees. When there is such a cutoff, a viewer may feel a luminance step on the screen, which is a practical problem.

FIG. 120 is a characteristic diagram showing the directional characteristics of red and blue image light obtained by the lenticular lens sheet 30 'of FIG. FIG. 120 shows characteristics when the concentration angle is smaller than that in the case of FIG. 119.

As shown in FIG. 120, when the horizontal viewing angle α is 4
At 5 degrees, a 50% difference in relative luminance occurs, which causes a color shift. Therefore, it is necessary to greatly reduce the difference between the relative luminances of the red and blue image lights.

As described above, the conventional transmission screen has a problem that the reduction of the color shift is insufficient.

A third problem is to reduce moire.

As described above, in the conventional transmission screen, the pitch of the horizontally long lenticular lens is set to an appropriate value for reducing moiré, but a sufficient effect is not necessarily obtained. This is a factor that determines the intensity of moiré. Besides, due to the light condensing characteristic of the projected image light by the horizontally long lenticular lens, the high-luminance portion and the low-luminance portion on the light exit surface 12 of the Fresnel lens sheet 10 are screened. This is due to the fact that light and dark lines are alternately arranged in the vertical direction of the screen, and will be briefly described below.

FIG. 121 is a characteristic diagram showing a luminance distribution in the vertical direction of the screen screen caused by the light condensing characteristic of the horizontally long lenticular lens, and is perpendicular to the light incident surface 11 of the Fresnel lens sheet 10 of the transmissive screen 1 in FIG. FIG. 7 is a characteristic diagram showing a comparison between a luminance distribution in a horizontal direction and a luminance distribution in a vertical direction of a screen screen by a horizontally long lenticular lens in a transmissive screen of the present invention described later.

In FIG. 121, the broken line 2 is the luminance distribution in the case of the horizontally long lenticular lens of the Fresnel lens sheet 10 according to the prior art shown in FIG. A solid line 1 is a luminance distribution by a horizontally long lenticular lens in an embodiment of the present invention described later, and the details will be described in the section of the embodiment of the present invention.

FIG. 108 shows a state in which image light is condensed by the horizontally long lenticular lens. That is, the light beam incident on the light incident surface 11 of the Fresnel lens sheet 10 is once focused at the focal point (not shown) in the Fresnel lens sheet 10 due to the shape of the horizontally long lenticular lens on the light incident surface 11 as described above. ,afterwards,
The light diverges to reach the light emitting surface 12. At this time, the image light corresponding to each pixel of the image source is diffused within a certain angle range.

The range of this diffusion is very narrow, and the vertical directional characteristics are such that both ends are sharp as shown in FIG. 114. Therefore, the luminance distribution in the vertical direction of the screen screen on the light emitting surface 12 is as shown in FIG. At 121, the distribution is as shown by the broken line 2. That is, in the light emitting surface 12, the portions having a low relative luminance and the portions having a high relative luminance are alternately arranged in the vertical direction of the screen screen to generate light and dark lines which cause moire, and the difference in luminance is very large. Therefore, the strength of the moire also increases.

As described above, the conventional transmissive screen has a problem that the reduction of moire is insufficient.
Reducing the luminance difference between the light and dark lines as described above is an important issue for reducing moiré.

An object of the present invention is to solve the above-mentioned conventional problems, to provide good focus characteristics, brightness and contrast of an image, wide directional characteristics in a horizontal direction and a vertical direction on a screen screen, and a color image. It is an object of the present invention to provide a transmissive screen with less shift and moiré, and a rear projection type image display device having the same.

[0078]

In order to achieve the above object, a transmission screen of a rear projection type image display apparatus according to the present invention comprises a Fresnel lens sheet, a first lenticular lens sheet, and a second lenticular lens sheet. And a three-piece configuration. Alternatively, in addition to this, a translucent colored light absorbing sheet is arranged closest to the image viewing side to form a four-sheet structure. Then, the shape of the light incident surface or the light emitting surface of the first lenticular lens sheet, or both, is a shape in which a plurality of aspherical horizontally long lenticular lenses whose longitudinal direction is the screen screen horizontal direction are arranged in the screen screen vertical direction. I do. Alternatively, the shape of the light incident surface or light emitting surface of the Fresnel lens sheet is a shape in which a plurality of aspherical horizontally long lenticular lenses whose longitudinal direction is the screen screen horizontal direction are arranged in the screen screen vertical direction. Alternatively, the shape of the light incident surface and / or the light emitting surface of the light absorbing sheet, or both of them, is a shape in which a plurality of aspherical horizontally long lenticular lenses whose longitudinal direction is in the horizontal direction of the screen screen are arranged in the vertical direction of the screen screen. Further, the shape of the light incident surface and the light emitting surface of the second lenticular lens sheet is a shape in which a plurality of aspherical vertically long lenticular lenses whose longitudinal direction is the screen screen vertical direction are arranged in the screen screen horizontal direction.

The light diffusion in the vertical direction of the screen is mainly performed by using a horizontally long lenticular lens provided on the light entrance surface or the light exit surface of the first lenticular lens sheet, or both, or a Fresnel lens sheet or light absorption sheet. This is performed by using a horizontally long lenticular lens provided on the light incident surface and / or light emitting surface of the first lenticular lens sheet, and the light diffusing material of the first lenticular lens sheet, the light diffusing material of the second lenticular lens sheet, or light absorption The configuration is such that the light diffusion material of the sheet is used. Further, the light diffusion in the horizontal direction of the screen screen is mainly performed by vertically elongated lenticular lenses provided on the light incident surface and the light exit surface of the second lenticular lens sheet.

The above-mentioned horizontally long lenticular lens and vertically long lenticular lens greatly improve the directivity of image light of each color in the vertical direction and the horizontal direction of the screen by optimizing the shape.

Further, among the Fresnel lens sheet, the first lenticular lens sheet, the second lenticular lens sheet and the light absorbing sheet, the thickness of the first lenticular lens sheet is minimized.

In order to achieve the above object, a rear projection type image display apparatus according to the present invention includes the above-mentioned transmissive screen according to the present invention and, among the lens groups constituting the projection lens, generates the most image. The lens arranged on the side close to the source is constituted by a concave lens having a convex surface on the image source side and a concave surface on the transmission screen side, and the image source and the projection lens are combined by a coupler. It is combined with a conventional contrast improvement technique of sealing a liquid refrigerant in a space formed between the image generating source and the concave lens in the coupler. Alternatively, in addition to this, a reflecting mirror composed of a base material and a light-reflective optical thin film is provided in the projection optical path from the projection lens to the transmission screen, and the reflecting mirror is configured as a surface of the base material of the reflecting mirror. The light-reflective optical thin film is formed on one surface facing the projection lens and the transmission screen, or the reflection mirror is formed on one surface facing the projection lens and the transmission screen on the surface of the base material of the reflector. And a conventional technique for improving the focus characteristics of an image, in which an anti-reflection film is provided on the substrate, and a light-reflective optical thin film is formed on the surface of the substrate opposite to the anti-reflection film.

[0083]

In the rear projection type image display apparatus using the transmission type screen having the above-mentioned configuration, light emitted from an image generation source such as a projection type cathode ray tube enters the transmission type screen through the projection lens, and is transmitted to the transmission type screen. After passing as substantially parallel light in the Fresnel lens sheet arranged on the image source side, the light is diffused in the vertical direction of the screen screen by the horizontally long lenticular lens of the light incidence surface or light emission surface of the first lenticular lens sheet,
Then diffused in the horizontal direction of the screen screen by the first vertically elongated lenticular lens of the light incident surface of the second lenticular lens sheet and the second vertically elongated lenticular lens of the light emitting surface, further, when a light absorbing sheet is arranged, The light passes through the light absorbing sheet and exits to the image viewing side.

At this time, the light diffusion in the horizontal direction of the screen screen is controlled by the shape of the aspherical vertically long lenticular lens provided on the light incidence surface or light emission surface of the second lenticular lens sheet. It is possible to expand the directional characteristics of the direction and further suppress the occurrence of color shift as much as possible.

The light diffusion in the vertical direction of the screen screen mainly depends on the first lenticular lens sheet, Fresnel lens sheet, or light absorbing sheet.
Because it is controlled by the shape of the aspherical horizontally long lenticular lens provided on the light entrance surface or light exit surface, it is possible to expand the directivity of the screen screen in the vertical direction and increase the vertical viewing angle by optimal design of the aspheric shape. it can.

In the present invention, as described above,
The horizontal lenticular lens of the first lenticular lens sheet, Fresnel lens sheet and light absorbing sheet can sufficiently expand the directional characteristics in the vertical direction of the screen screen, so that the first lenticular lens sheet, the second lenticular lens sheet, or the light The light-diffusing material may not be contained in the absorbing sheet at all, or may be contained in a very small amount. Therefore, the image is less likely to be blurred by the light diffusing material, and good focus characteristics can be obtained. In addition, since the incident light is less scattered by the light diffusing material to generate stray light, and the external light such as illumination light is also less scattered by the light diffusing material, the image is compared with the conventional transmissive screen. Brightness,
The contrast is improved.

On the other hand, by reducing the thickness of the first lenticular lens sheet among the Fresnel lens sheet, the first lenticular lens sheet, and the second lenticular lens sheet, the horizontal length of the first lenticular lens sheet is reduced. Since the lenticular lens and the vertically elongated lenticular lens on the light incident surface of the second lenticular lens sheet can be arranged so as to be close to each other, the starting point of light diffusion of the incident light beam in the horizontal direction of the screen screen and the vertical point of the screen screen in the vertical direction Since the start point of light diffusion is close, the focus characteristic is further improved.

Further, when a translucent colored light absorbing sheet is arranged on the image viewing side of the transmissive screen, the projected image light from the image generation source side to the image viewing side is Since the light passes through the light-absorbing sheet only once, the amount of light attenuates in proportion to the transmittance of the light-absorbing sheet, whereas external light such as illumination light is reflected by the transmissive screen and reaches the image viewing side. At the time, most of the external light passes through the light absorbing sheet at least one reciprocation except for the light reflected on the light exit surface of the light absorbing sheet which is closest to the image viewing side. Decays in proportion to the square. Therefore, the ratio of the loss light of the external light is larger than that of the projection light, and the contrast when the external light such as the illumination light is present is improved.

When the light-absorbing sheet is not provided, the second lenticular lens sheet may be colored translucently. In this case, as in the case where the light-absorbing sheet is provided, the illumination light The contrast in the presence of external light, such as, is improved.

The shape of the horizontally long lenticular lens provided on the light entrance surface or light exit surface of the first lenticular lens sheet is optimized, and the luminance distribution in the vertical direction of the screen screen on the light exit surface has a low relative luminance. When the luminance difference between the high-frequency portion and the high-frequency portion is reduced, moire generated by the Fresnel lens, the horizontally long lenticular lens, and the vertically long lenticular lens can be reduced.

[0091]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a perspective view showing a main part of a transmission screen as a first embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a transmissive screen, which in this embodiment has a three-lens structure including a Fresnel lens sheet 10, a first lenticular lens sheet 20, and a second lenticular lens sheet 30. Fresnel lens sheet 10, first lenticular lens sheet 20,
The second lenticular lens sheets 30 are fixed to each other at ends (not shown). 10B, 20
Reference numerals B and 30B denote base materials of the Fresnel lens sheet 10, the first lenticular lens sheet 20, and the second lenticular lens sheet 30, respectively, each of which is made of a substantially transparent thermoplastic resin material.

The Fresnel lens sheet 10 has a light incident surface 1
1 has a flat surface, and the light exit surface 12 has a Fresnel convex lens shape.

The first lenticular lens sheet 20
The light incident surface 21 has a shape in which a plurality of horizontally long lenticular lenses whose longitudinal direction is in the horizontal direction of the screen screen are arranged continuously in the vertical direction of the screen screen, and the light emitting surface 22 has a flat shape.

Second lenticular lens sheet 30
The light incident surface 31 has a shape in which a large number of first longitudinal lenticular lenses whose longitudinal direction is the screen screen vertical direction are continuously arranged in the horizontal direction of the screen screen, and the shape of the light exit surface 32 is The second vertically elongated lenticular lens whose longitudinal direction is in the screen screen vertical direction is substantially opposed to the first vertically elongated lenticular lens on the light incident surface 31 and is continuously arranged in a horizontal direction on the screen screen. Further, at the boundary between the second vertically long lenticular lenses, a convex protrusion 32P is provided, and a light absorption band 33 having a finite width is provided thereon.

This embodiment corresponds to FIG. 106 or FIG.
The difference from the conventional transmission screen shown in FIG.
As shown in the figure, the light incident surface 1 of the Fresnel lens sheet 10
1 is flat, the first lenticular lens sheet 20 having a small sheet thickness is newly added as a constituent element, and the first vertically elongated lenticular of the light incident surface 31 of the second lenticular lens sheet 30. The point that both the shape of the lens and the second longitudinal lenticular lens of the light exit surface 32 are different from the shape of the longitudinal lenticular lens of the lenticular lens sheet 30 ′ in the conventional transmission screen, and the second lenticular lens. The four points are that the light diffusing material 6 is not dispersed as fine particles in the base material 30B of the lens sheet 30.

Next, the Fresnel lens sheet 10, the first lenticular lens sheet 20, and the second lenticular lens sheet 30 constituting the transmission screen 1 shown in FIG. 1 will be described in detail from the Fresnel lens sheet 10. .

Light emitting surface 12 of Fresnel lens sheet 10
The Fresnel convex lens provided in the same manner as in the case of the Fresnel lens sheet of the conventional transmission screen, emits the luminous flux of the red, green, and blue projected image light incident on the entire light incident surface 11 for each color. It has a function of converting it into a substantially parallel light beam and making it incident on the first lenticular lens sheet 20.

FIG. 2 is a sectional view showing a main part of a rear projection type image display apparatus provided with the transmission type screen 1 of FIG. 1, and FIG. 3 is a projection optical system of the rear projection type image display apparatus of FIG. FIG. 3 is a schematic development view when is developed on a horizontal plane.

2 and 3, reference numeral 1 denotes a transmissive screen, 7R, 7G, and 7B denote projection CRTs of red, green, and blue, respectively, and 8R, 8G, and 8B denote projection CRTs 7R, 7G, and 7B, respectively. A projection lens 9G is a coupler for connecting the projection type cathode ray tube 7G and the projection lens 8G, and 10G.
0R, 100G, and 100B are red, green, and blue projection light beams, respectively. 110 is a projection light flux 100R, 100G, 1
FIG. 3 is a developed view in which the reflecting mirror 110 is omitted. Also, 12
0 casing, 130R, 130G, 130B is the optical axes of the projection lenses 8R, 8G, 8B, at a point S ₀ near the center of the transmissive screen 1, intersects the optical axis intensive angle theta.

In FIG. 2 and FIG.
R, 100G, and 100B are incident on the transmission screen 1 while spreading. Accordingly, the transmission screen 1
In each pixel of the above image, when viewing one particular color, for example, a red light ray, the principal ray of each pixel is not parallel, and the principal ray of the central pixel of the transmissive screen 1 is transmissive in a direction away from each other. The light enters the screen 1. At this time, for each pixel on the transmissive screen 1, the direction of the principal ray of each pixel is the direction in which the light intensity is the strongest. Therefore, for a viewer at a certain position, only a part of the image is bright, The surroundings will look very dark.

On the other hand, in the transmission type screen 1, the Fresnel lens sheet 10 is arranged such that the luminous flux of the image light incident on the entire light incident surface 11 is substantially parallel for each of red, green and blue. The first lenticular lens sheet 20 is converted by the Fresnel convex lens on the light emitting surface 12.
And has the effect of improving the distribution of screen brightness on the transmissive screen 1.

However, at this time, as described above, in FIG. 3, the green optical axis 130G intersects with the red optical axis 130R and the blue optical axis 130B at the optical axis concentrated angle θ. Accordingly, in each pixel on the transmissive screen 1, red,
The green and blue principal rays enter the Fresnel lens sheet 10 at different angles from each other and exit from the Fresnel lens sheet 10 at different angles. Therefore, the angles of incidence of the red, green, and blue light rays on the first lenticular lens sheet 20 are different from each other.

When the projected luminous flux of each color of red, green, and blue is diffused in the horizontal direction of the screen screen by the second lenticular lens sheet 30, the direction of the principal ray of each color becomes the brightest direction for each pixel. The balance of the three primary colors of red, green, and blue changes according to the horizontal position at which the viewer views the image, and the color of the image appears to change. This phenomenon is called “color shift”.

Next, the first lenticular lens sheet 20 will be described.

The horizontally long lenticular lens provided on the light incident surface 21 of the first lenticular lens sheet 20 transmits the incident light beam 140 similarly to the horizontally long lenticular lens on the light incident surface of the conventional transmissive screen Fresnel lens sheet. It has a function to diffuse in the screen screen vertical direction.

FIG. 4 is a sectional view showing a vertical section of the transmission screen 1 of FIG.

In FIG. 4, reference numeral 140 denotes an incident light beam.
In addition, the same portions as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

As shown in FIG. 4, when the incident light beam 140 is incident from the horizontally long lenticular lens of the light incident surface 21, the difference in the incident position on the light incident surface 21 is the same even for the same scanning line or the same pixel. Because of this, the incident angle becomes different, so that the light is refracted at a different angle and diffused in the vertical direction of the screen screen. At this time, if the radius of curvature of the horizontally long lenticular lens is reduced, the incident angle of the incident light beam 140 is increased as a whole, the light is diffused over a wider angle range, and the directional characteristics in the vertical direction of the screen are increased, and the vertical viewing angle is increased. The corners increase.

Here, the pitch of the horizontally long lenticular lens needs to be configured to be smaller than the pitch of the scanning lines of the projected image or the pitch of the pixels. Further, moire with the pitch of the scanning lines of the projected image, and It is necessary to consider the moire with the pitch of the annular zone of the Fresnel convex lens of the Fresnel lens sheet 10 in the upper and lower portions of the screen.

Of these, it is particularly necessary to pay attention to the moire caused by the pitch of the scanning line and the pitch of the horizontal lenticular lens. The pitch of the horizontal lenticular lens is made sufficiently smaller than the pitch of the first vertical lenticular lens in the horizontal direction of the screen. Furthermore, if the pitch of the scanning line is designed to be sufficiently smaller than the pitch of the scanning line and the pitch of the scanning line and the pitch of the horizontally long lenticular lens are not set to a simple integer ratio, the strength of the moire becomes a level that does not cause a practical problem.

For example, if the screen size is 800 m in the horizontal direction
m, the vertical direction is 600 mm, and the horizontal screen pitch of the transmission screen is 0.78 mm. Assuming that 450 horizontal scanning lines are displayed on the screen, the scanning line pitch is 1.33 mm. However, if the pitch of the ring zone of the Fresnel convex lens is selected to be about 0.105 mm and the pitch of the horizontally long lenticular lens is selected to be about 0.091 mm, the moire becomes very inconspicuous.

In the conventional transmission screens shown in FIGS. 106 and 107, the projected image light is mainly transmitted to the screen by the light diffusing material 6 dispersed as fine particles in the base material 30B 'of the lenticular lens sheet 30'. It was diffused in the vertical direction of the screen, and had a directional characteristic with a skirt.

On the other hand, as described above, since the light diffusing material 6 is not dispersed as fine particles in the base material 30B of the second lenticular lens sheet 30 in the present embodiment, the shape of the horizontally long lenticular lens is reduced. Is a simple columnar or elliptical columnar shape as in the case of a transmission screen according to the prior art, a cut-off occurs in the directional characteristics in the vertical direction of the screen without drawing a tail, and as a result, when a certain angle range is exceeded, projection occurs. The image light disappears, and the viewer cannot see the image. For this reason, in the present embodiment, the shape of the horizontally long lenticular lens is changed to the light diffusing material 6.
It is preferable to design the lens into an aspherical shape that can obtain a directional characteristic in which a skirt is drawn without the presence of a skirt. At this time, the difference in brightness due to the horizontally long lenticular lens array when the single lenticular lens sheet 20 is viewed from a certain direction is visually reduced due to the directivity characteristic of pulling the skirt. Therefore, the above-mentioned moiré becomes even less noticeable.

The horizontally long lenticular lens of the light incident surface 21 of the first lenticular lens sheet 20 is the horizontally long lenticular lens provided on the light incident surface 11 of the Fresnel lens sheet 10 in the conventional transmission screen 1 shown in FIG. It is an alternative to lenticular lenses. In the conventional transmissive screen 1, in order to increase the directional characteristics in the vertical direction of the screen screen, the amount of the light diffusing material in the base material 30B 'of the lenticular lens sheet 30' is increased, or the horizontally long lenticular lens of the Fresnel lens sheet 10 is used. When the radius of curvature of was decreased, the focus characteristics deteriorated as described above.

On the other hand, in this embodiment, even if the radius of curvature of the horizontally long lenticular lens is reduced in order to expand the directivity in the vertical direction of the screen, the focus characteristic does not deteriorate.

This is because the sheet thickness of the first lenticular lens sheet 20 is made smaller than the sheet thickness of the Fresnel lens sheet 10 and the second lenticular lens sheet 30 and the light incident surface 21 of the first lenticular lens sheet 20 is made smaller. And the vertical lenticular lens of the second lenticular lens sheet 30 on the light incident surface 31 are arranged close to each other. That is, in the present embodiment, since the start point of the light diffusion of the incident light beam 140 in the horizontal direction of the screen screen and the start point of the light diffusion in the vertical direction of the screen screen are close to each other, the focus characteristic does not deteriorate.

More specifically, as shown in FIG. 4, after the incident light beam 140 passes through the Fresnel lens sheet 10,
Light incident surface 21 of first lenticular lens sheet 20
After being refracted by the shape of the horizontally long lenticular lens, once focused at the focal point f ₀ , diverged as it is and diffused in the vertical direction of the screen screen, it is not diffused in the vertical direction of the screen screen. This light flux is emitted from the light exit surface 22 of the first lenticular lens sheet 20 and immediately after the second lenticular lens sheet 30.
Is diffused in the horizontal direction of the screen screen in the vertical lenticular lens of the light incident surface 31 of the light incident surface 31. Therefore, when viewed from the image viewing side, the width d of the outgoing light beam relative to the incident light beam 140 in the screen screen vertical direction is substantially equal to the Fresnel lens. Recognized by the width of the light beam appearing on the light exit surface 12 of the sheet 10, it is smaller than the light beam width d of the conventional transmission screen shown in FIG. 117, and the image is not blurred.

FIG. 5 shows a case where the sheet thickness of the first lenticular lens sheet 20 is smaller than the sheet thickness of the Fresnel lens sheet 10 and the second lenticular lens sheet 30 as described above (the light exit surface 22 is indicated by a solid line). ) And the case where the sheet thickness of the Fresnel lens sheet 10 of the conventional transmission screen shown in FIG. 107 is as thick as the sheet thickness (the light exit surface 22 is indicated by a dashed line).
It is an expanded sectional view which shows and compares the cross section of a screen screen perpendicular direction.

As shown in FIG. 5, the light beam incident on the light incident surface 21 of the first lenticular lens sheet 20 is focused on the focal point f in the first lenticular lens sheet 20 by the shape of the horizontally long lenticular lens on the light incident surface 21. _The light is once focused at ₀ , and then diverges to reach the light exit surface 22.

When the sheet thickness of the first lenticular lens sheet 20 is large (when the light emitting surface 22 is at the position indicated by the dashed line and the sheet thickness is t ₁ ), the width d of the light beam on the light incident surface 21 is ₀ and the width d ₂ of the light flux on the light exit surface 22
In comparison with the above, the width d ₂ of the light flux on the light emitting surface 22 is larger. For this reason, even if the light diffusing material 6 is eliminated, the scanning line width or the pixel size on the light emitting surface 22 of the first lenticular lens sheet 20 increases, and as a result, the focus characteristics deteriorate. When the radius of curvature of the horizontally long lenticular lens on the light incident surface 21 is reduced in order to enlarge the directivity in the vertical direction of the screen screen, the focus characteristic is further deteriorated because the width d ₂ of the light beam on the light exit surface 22 is further increased. .

On the other hand, when the sheet thickness of the first lenticular lens sheet 20 is smaller than the sheet thickness of the Fresnel lens sheet 10 and the second lenticular lens sheet 30 as described above (when the light exit surface 22 is at the position indicated by the solid line). When the sheet thickness is t ₀ ), the light beam width d _{1 on} the light exit surface 22 is smaller than the light beam width d ₂ on the light exit surface 22 when the sheet thickness is t ₁ , This is almost equal to the width d ₀ of the light beam on the light incident surface 21. At this time, the scanning line width or the pixel size on the light emitting surface 22 of the first lenticular lens sheet 20 is also reduced, and the vertical direction of the screen screen at the starting point of light diffusion in the horizontal direction on the second lenticular lens sheet 30 is reduced. The width of the light beam is reduced, and the focus characteristics are improved. In addition, as described later, when the vertical directional characteristics of the first lenticular lens sheet 20 have a flared characteristic as shown in FIG. 30, the deterioration of the focus characteristic is hardly recognized.

In this embodiment, since the first lenticular lens sheet 20 is thinner than the Fresnel lens sheet 10 and the second lenticular lens sheet 30, the first lenticular lens sheet 20 is mechanically singly. Although the strength is weak, the sheet thickness of the Fresnel lens sheet 10 and the second lenticular lens sheet 30 is sufficiently increased, and the first lenticular lens sheet 20 is sandwiched between the Fresnel lens sheet 10 and the second lenticular lens sheet 30. A practical problem is caused by the configuration in which the bending rigidity of the Fresnel lens sheet 10 and the second lenticular lens sheet 30 is sufficiently larger than the bending rigidity of the first lenticular lens sheet 20. No.

However, even in such a case, when the transmissive screen 1 is mounted on the rear projection type image display device, there is a possibility that the sheets may float and not adhere to each other. Therefore, in order to prevent this floating, the Fresnel lens sheet 10 and / or the second lenticular lens sheet 30, or both of them, are previously warped so that they are closer to each other near the center of the screen than at the periphery of the screen. Then, it is mounted on the rear-projection image display device, or mounted on the rear-projection image display device in a state where a tensile force is applied to the periphery of each sheet so as to generate an in-plane tension. Is preferred.

Next, the second lenticular lens sheet 30 will be described.

In FIG. 1, the first vertically elongated lenticular lens provided on the light incident surface 31 of the second lenticular lens sheet 30 is a Fresnel lens sheet 10.
Has a function of diffusing the luminous flux of the projected image light emitted from the image screen in the horizontal direction of the screen screen for each pixel and emitting the luminous flux to the image viewing side.

In the lenticular lens sheet of the conventional transmission screen described in the above-mentioned Japanese Patent Application Laid-Open No. 58-59436, the first vertically long lenticular lens has a plurality of elliptical cylindrical surfaces arranged continuously. It was a shape. The ellipse has the long axis direction in the thickness direction of the lenticular lens sheet 30 ′, one of the two focal points of the ellipse is located inside the base 30 B ′, and the other focal point is the light exit surface 3.
It was configured to be located near 2 '. Further, the eccentricity e of the ellipse is selected so as to be substantially the reciprocal of the refractive index n of the base material 30B '.

In the lenticular lens sheet 30 'of the conventional transmissive screen 1 shown in FIGS. 106 and 107, as described above, the projected image light is transmitted in the horizontal direction of the screen by the vertically long lenticular lens of the light incident surface 31. In addition to being diffused, the light is diffused slightly further by the light diffusing material 6 dispersed as fine particles in the base material 30B 'of the lenticular lens sheet 30'.
It had a directional characteristic with a skirt.

On the other hand, as described above, since the light diffusing material 6 is not dispersed as fine particles in the base material 30B of the second lenticular lens sheet 30 in this embodiment, the first vertically long lenticular lens sheet 30 is not used. When the shape of the lens is the same as that of the conventional lenticular lens sheet 30 ', a cutoff occurs in the directional characteristic in the horizontal direction of the screen screen without trailing. As a result, when the angle exceeds a certain angle range, the projected image light is reduced. And the image becomes invisible to the viewer. For this reason, in this embodiment,
The shape of the first vertically long lenticular lens is changed to the light diffusing material 6.
It is necessary to design the shape so that a wide directional characteristic can be obtained such that a hem is drawn without the presence of the directional pattern.

On the other hand, the second vertically long lenticular lens provided on the light emitting surface 32 of the second lenticular lens sheet 30 has a surface substantially symmetrical to the shape of the first vertically long lenticular lens. The second vertically long lenticular lens has a function of making the directional characteristics of the emitted light beams of these colors substantially parallel to each other for the incident light beams of red, green, and blue, and significantly reduces the color shift described above. There is an effect that can be reduced.

In the present embodiment, as described later, the first vertically elongated lenticular lens shape is such that the light beam incident on the second lenticular lens sheet 30 and the second vertically elongated lenticular lens Is designed so that it passes only near the center of the lens and does not pass near the boundary between the adjacent vertically long lenticular lens surfaces on both sides. In the vicinity of the boundary, a convex protrusion 3 having a finite width is provided.
2P is provided, and a light absorption band 33 is provided thereon.

The light absorption band 33 has a function of absorbing a part of the external light without reflecting it when external light such as illumination light is incident. This has the effect of improving the contrast of the image.

On the other hand, in the present embodiment, as described above, the horizontally long lenticular lens provided on the light incident surface 21 of the first lenticular lens sheet 20 is used.
Since the directivity of the screen screen in the vertical direction can be sufficiently widened, the base material 30B of the second lenticular lens sheet 30 contains fine particles, unlike the lenticular lens sheet 30 'of the conventional transmission screen, unlike the conventional case. The light diffusing material 6 is not dispersed.

Therefore, as described above, the incident light beam 140 incident on the Fresnel lens sheet 10 is refracted by the shape of the horizontally long lenticular lens on the light incident surface 21 of the first lenticular lens sheet 20 and diffuses in the direction perpendicular to the screen of the screen. After that, when the light passes through the second lenticular lens sheet 30, the light is not diffused in the vertical direction of the screen by the light diffusing material, so that the image is not blurred and good focus characteristics are obtained.

Further, since the incident light on the light incident surface 31 of the second lenticular lens sheet 30 is not scattered by the light diffusing material 6 before reaching the light exit surface 32, stray light is not generated. Brightness and contrast of an image are improved as compared with a transmissive screen. Further, since external light incident on the light exit surface 32 is not scattered by the light diffusing material 6, there is an effect that the contrast of an image is remarkably improved as compared with a conventional transmission screen.

Next, design examples of the horizontally long lenticular lens of the first lenticular lens sheet 20 and the vertically long lenticular lens of the second lenticular lens sheet 30 in this embodiment will be described more specifically.

FIG. 6 shows a coordinate system for defining the aspherical shape of each lenticular lens. The optical axis direction of the lens is defined as the Z axis, and the direction in which the light beam travels is defined as a positive (+) direction.
The axis in the radial direction perpendicular to the Z axis is defined as the R axis, and the radial distance from the Z axis is defined as r. At this time, the surface shape of the lens (hereinafter, referred to as
Z (r) (defined as sag amount) is defined by Expression 2.

[0139]

(Equation 2)

In Equation 2, r and Z (r) are expressed in units of mm. RD represents the radius of curvature, and CC,
AE, AF, AG, and AH are aspherical coefficients. Although Equation 2 shows only the tenth term of r, the present invention is not limited to this. As shown in Equation 3, the same may be set for even-order terms of 12th or higher.

[0141]

(Equation 3)

Here, n is an arbitrary natural number, and _An is an aspheric coefficient of a 2n-th order term.

Here, the maximum effective radius of the lenticular lens in the R-axis direction is defined as r _MAX, and the relative radius ρ of the lenticular lens is defined by Expression 4.

[0144]

(Equation 4)

First, a design example of a vertically long lenticular lens of the second lenticular lens sheet 30 will be described.

First, technical means for expanding the horizontal viewing angle α will be described with reference to FIGS. 7 and 8.

FIG. 7 is a horizontal sectional view of the second lenticular lens sheet 30 in FIG. 1, and FIG. 8 is a horizontal sectional view of a general lenticular lens sheet 30 'according to the prior art.

As shown in FIG. 8, when the shape of the first vertically long lenticular lens on the light incident surface 31 'is a spherical shape, the optical axes l and l' of the incident light flux 140 (image light beam) are obtained.
A light beam passing near (indicating the height in the figure h _0), the optical axis l, a light beam passing through a location remote from l '(indicating the height in the figure h _2), the light incident surface 31 ′ Differs from each other, and the imaging position near the light exit surface 32 ′ differs. That is, the image forming position by the light beam passing away from the optical axes l and l 'is closer to the light incident surface 31' than the image forming position by the light beam passing near the optical axes l and l '.

This is generally called longitudinal spherical aberration. Therefore, as described above, the position of the image formed by the light beam passing through a place distant from the optical axes l and l 'is smaller than the position of the image formed by the light beam passing near the optical axes l and l'. Is referred to as “positive longitudinal spherical aberration” below, and conversely, the image formation position by light rays passing near the optical axes l and l ′ is
The case where the position closer to the light incident surface 31 ′ than the image forming position by the light beam passing through the places distant from the optical axes l and l ′ is hereinafter referred to as “negative longitudinal spherical aberration”.

In this embodiment, the light incident surface 31
Is not a spherical shape as shown in FIG.
The shape is as shown in FIG. That is, the optical axis l,
The imaging position by the light beam passing near l ′ approaches the light incident surface 31 (that is, negative longitudinal spherical aberration) from the imaging position by the light beam passing away from the optical axes l and l ′, Further, the lens shape is such that an image forming position by a light beam passing near the optical axes l and l 'is near the light exit surface 32. Further, the shape of the light emitting surface 32 is convex toward the image viewing side.

When the light incident surface 31 and the light emitting surface 32 are formed in such a shape, the light rays passing through the places distant from the optical axes l and l 'enter the light emitting surface 32 at an angle close to the critical angle. Therefore, the image light beam is largely refracted at the light exit surface 32. Therefore, the horizontal viewing angle α can be greatly increased as compared with the conventional lenticular lens sheet 30 ′.

Next, technical means for reducing the color shift will be described with reference to FIG.

As described above, the red or blue image light is
As shown in FIG. 9, the second lenticular lens sheet 3
The light enters the zero light incident surface 31 as an incident light beam 140 from an oblique direction. Therefore, in order to reduce the color shift,
It is necessary that the image light beam A located substantially at the center of the incident light beam 140 be refracted by the light exit surface 32 and then be substantially parallel to the optical axes l and l '.

Therefore, in the present embodiment, the shapes of the light incident surface 31 and the light emitting surface 32 are changed so that the image light beam A located substantially at the center of the incident light beam 140 is refracted by the light emitting surface 32 and then the optical axes l and l '.
The lens shape is such that light is emitted substantially parallel to the lens.

Table 1 shows the first design example of the lens shape of the light entrance surface 31 and the light exit surface 32 for increasing the horizontal viewing angle α and reducing the color shift. Shows the spherical coefficient, surface spacing, refractive index, and effective radius.

[0156]

[Table 1]

In Table 1, the light incident surface 31 (S in the table)
The radius of curvature of ₀ displayed) is 0.28845Mm, the optical axis l from the light incident surface 31 to the light emitting surface 32 (indicated by S ₁ in the table), the distance on the l '(surface distance) is 0. 88mm,
It is shown that the refractive index of the medium in between is 1.493.

If the sign of the radius of curvature is positive (+), it indicates that the center of curvature of the lens surface is located in a direction from the lens surface toward the light exit surface toward the light exit surface.

FIG. 10 is a characteristic diagram showing the horizontal directivity characteristics of the second lenticular lens sheet 30 corresponding to the lens shape data in Table 1, and FIG. 11 is the second lenticular lens sheet 30 corresponding to the lens shape data in Table 1. FIG. 6 is a characteristic diagram showing horizontal directional characteristics of red or blue image light of the lenticular lens sheet 30 of FIG.

As shown in FIG. 10, the horizontal viewing angle α is ± 6.
At 7 degrees, it was significantly larger than the transmission screen of the prior art. The direction in which the luminance becomes 50% of the luminance in the screen front direction is a direction of ± 42 degrees from the screen front direction,
Practical enough performance has been obtained. Further, as shown in FIG. 11, the color shift was reduced by half as compared with the transmission screen of the prior art.

FIG. 12 is a graph showing the characteristics of the change in the lens action with respect to the shape of the light incident surface of the second lenticular lens sheet 30 in comparison between the screen corresponding to the lens shape data in Table 1 and the conventional screen. FIG.

In FIG. 12, the vertical axis represents the second derivative of Z (r) of Equation 2 that defines the shape of the first vertically long lenticular lens, and the horizontal axis represents the lens effective radius P / 2 (1).
Is a relative value (relative radius) of the radial distance. The solid line 1 indicates the characteristics of the screen of the related art, and the broken line 2 indicates the characteristics of the screen corresponding to the lens shape data shown in Table 1.

By looking at the increase and decrease of the value of the second derivative, it is possible to know the change of the lens action depending on each position of the lens in the radial direction. In other words, the lens shape (convex toward the image light source side) of the light incident surface in this embodiment becomes negative as the second-order differential value moves away from the optical axes l and l ', as shown by the broken line 2. For this reason, the lens function is weakened. On the other hand, the lens shape (convex to the image light source side) of the light incident surface in the prior art is
As shown by the solid line 1, the secondary differential value becomes positive as the distance from the optical axes l and l 'increases. For this reason, the shape is such that the lens action is enhanced.

FIG. 13 shows the characteristics of the change in the lens action relating to the shape of the light exit surface of the second lenticular lens sheet 30 as compared between the screen corresponding to the lens shape data in Table 1 and the conventional screen. FIG.

In FIG. 13, the vertical axis represents the second derivative of Z (r) of Equation 2 that defines the shape of the second vertically long lenticular lens, and the horizontal axis represents the lens effective radius P / 2 (1).
Is the relative value (relative radius) of the radial distance. The solid line 1 indicates the characteristics of the screen of the related art, and the broken line 2 indicates the characteristics of the screen corresponding to the lens shape data shown in Table 1.

The lens shape (convex to the viewing side) of the light exit surface of this embodiment is such that the second derivative value is the optical axis l, as shown by the broken line 2.
It becomes positive as it moves away from l '. For this reason, it has a shape in which the lens action (light collecting action) is weakened. On the other hand, the lens shape (convex to the viewing side) of the light exit surface of the prior art, as shown by the solid line 1, is such that the second derivative value is a negative constant value even at a position away from the optical axes l and l '. ing. For this reason, the shape is such that the lens action (light collecting action) does not change.

Table 2 shows the radius of curvature and the aspherical coefficient in Equation 2 for the second design example of the lens shapes of the light entrance surface 31 and the light exit surface 32 for increasing the horizontal viewing angle α and reducing the color shift. , Surface spacing, refractive index, and effective radius.

[0168]

[Table 2]

FIG. 14 is a characteristic diagram showing the horizontal directivity characteristics of the second lenticular lens sheet 30 corresponding to the lens shape data in Table 2, and FIG. 15 also corresponds to the lens shape data in Table 2. FIG. 9 is a characteristic diagram showing horizontal directional characteristics of the second lenticular lens sheet 30 for red or blue image light.

As shown in FIGS. 14 and 15, this second design example also provides a horizontal viewing range of ± 68 degrees with a color shift equal to or less than that of the transmission type screen of the prior art. It can be greatly expanded compared to the screen.

Table 3 shows a third design example of the lens shape of the light entrance surface 31 and the light exit surface 32 of the second lenticular lens sheet 30.

[0172]

[Table 3]

FIG. 16 is a ray tracing diagram when a green parallel light beam is incident on the second lenticular lens sheet 30 according to the design example in Table 3. In the design example of Table 3, in order to eliminate the cut-off, as shown in FIG.
The relative radius of the first longitudinal lenticular lens of 1.
The curvature of the portion close to 0 (the portion distant from the optical axis) is reduced, and the light in the peripheral portion of the incident parallel light beam is diffused.

FIG. 17 shows the red, lenticular lens sheet 30 corresponding to the lens shape data in Table 3.
FIG. 4 is a characteristic diagram illustrating horizontal directional characteristics of video light of each color of green and blue.

In FIG. 17, the light beam concentration angle is 10 °.

As shown in FIG. 17, by forming the first longitudinal lenticular lens of the light incident surface 31 in the horizontal sectional shape to be a higher order aspherical surface, compared with the case where the sectional shape is made elliptical by the prior art, The color shift can be greatly reduced in design. For example, the color shift at a viewing angle of 30 ° is 1.1 dB. In addition, this directivity characteristic is superior to the case where the horizontal cross-sectional shape is elliptical, in that there is no sharp decrease in luminance due to cutoff.

In the second lenticular lens sheet 30 according to each of the above-described design examples, 1,000 or more fine vertical lenticular lenses are formed by resin extrusion molding. For example, the screen size of the transmission screen is 800 mm in the horizontal direction of the screen screen, and the pitch of one vertically long lenticular lens is 0.7 mm.
When the length is 3 mm, about 1200 vertically long lenticular lenses are formed on the light incident surface 31 and the light exit surface 32 of one second lenticular lens sheet 30, respectively. Therefore, in order to obtain the expected performance for each of the above design examples, in order to suppress variations in the shape of the cross-sectional shape of each vertically elongated lenticular lens caused by the processing conditions and molding conditions of the roll die, high precision is required. It needs to be molded.

The deterioration of the directivity characteristics due to errors in the cross-sectional shape will be described below with reference to the third design example shown in Table 3 as an example.

FIG. 18 shows an actual prototype of the second lenticular lens sheet 30 based on the third design example shown in Table 3, which was used as a transmission screen having the structure shown in FIG. The results of measuring the horizontal directional characteristics of the video light of each blue color are shown. Note that the horizontal directional characteristics in FIG. 18 have a concentration angle of 10 °.

As shown in FIG. 18, when the second lenticular lens sheet 30 was actually produced as a trial, the directivity characteristics of the second lenticular lens sheet 30 were 2.1 dB at a viewing angle of 30 ° and the calculation shown in FIG. It is almost twice the value. Furthermore, a singular point at which the viewing luminance sharply increases (hereinafter, referred to as a singular point of the viewing luminance) occurs at a position at a viewing angle of −32 ° of the red light and at a position of 43 ° at a viewing angle of the blue light. As a result, vertical stripes of red and blue were generated on the screen, which was problematic in practical use.

FIG. 19 shows the measured shape (31M) of the horizontal cross-sectional shape of the first vertically elongated lenticular lens on the light incident surface 31 of the prototyped second lenticular lens sheet 30.
Is shown in comparison with the design shape (31D).

As shown in FIG. 19, distortion (shape error) has occurred in the horizontal cross-sectional shape of the prototyped second lenticular lens sheet 30 with respect to the design value. For example, at the position where the relative radius r of the first vertically elongated lenticular lens on the light incident surface 31 is 1.0, the sag amount of the design value is about 0.28 mm, and the sag amount of the measured value is also equal to the sag amount of the design value. Although they are almost the same, at a position where the relative radius r is around 0.7, the sag amount of the measured value is smaller than the sag amount of the design value, and the horizontal cross-sectional shape of the vertically long lenticular lens is an expanded shape. Has become.

FIG. 20 shows the magnitude of the distortion of the sag amount of the measured value of the prototype, based on the sag amount of the design value, with respect to the horizontal sectional shape of the first vertically elongated lenticular lens on the light incident surface 31. FIG. 4 is a characteristic diagram showing the distribution of the. The distortion in the horizontal cross-sectional shape of the first vertically elongated lenticular lens of the prototype was maximum when the relative radius r was approximately 0.7, and the size was 0.008 mm.

The problem of distortion in forming the horizontal cross-sectional shape of such a vertically long lenticular lens has not been completely solved by the current manufacturing technology. A sag amount error of about 0.01 mm may occur in the axial direction. However, if it becomes possible to realize a shape almost as designed by increasing the precision of the manufacturing technology, characteristics as designed as in the above-described respective design examples will be obtained.

Here, a description will be given of a design example in which even if there is some distortion in the horizontal cross-sectional shape of the first vertically elongated lenticular lens on the light incident surface 31, the characteristic is less deteriorated.

A transmissive screen is designed that has no cutoff in directional characteristics, has little color shift, and has no singular point of visual luminance even when the cross-sectional shape of a vertically long lenticular lens is distorted during molding. To do
The present inventors first measured some cross-sectional shapes of a vertically long lenticular lens of a conventional lenticular lens sheet, and analyzed the relationship with the directional characteristics. As a result, it was found that distortion of the cross-sectional shape of the vertically elongated lenticular lens on the light emitting surface with respect to the design shape hardly occurred because the effective width of the vertically elongated lenticular lens on the light emitting surface was small and the shape was gentle. Was.

On the other hand, with respect to the cross-sectional shape of the vertically elongated lenticular lens on the light incident surface, many distortions having the same tendency as that shown in FIG.

Therefore, regarding the cross-sectional shape of the first vertically elongated lenticular lens on the light incident surface 31 of the second lenticular lens sheet 30, a singular point of visual luminance appears especially when distortion of the type shown in FIG. 20 occurs. With a focus on the absence of this, the second derivative of the cross-sectional shape of the vertically elongated lenticular lens on the light incident surface 31 was focused on. Here, the second derivative of the cross-sectional shape of the vertically long lenticular lens approximately represents the curvature at each relative radius of the vertically long lenticular lens.
For example, the second derivative of a parabola is a constant value regardless of the position of the relative radius.

FIG. 21 shows the second derivative of the cross-sectional shape when the cross-sectional shape of the first vertically elongated lenticular lens on the light incident surface 31 is the ellipse shown in FIG. 110, and similarly, the ellipse at the center of the lens. A comparison with a second derivative of a cross-sectional shape in the case of a parabola having the same curvature is shown. 20 also shows the second derivative of the cross-sectional shape when it is assumed that the distortion shown in FIG. 20 occurs in the vertically elongated lenticular lens having the parabolic cross-sectional shape.

As shown in FIG. 21, when the distortion shown in FIG. 20 occurs in the sectional shape of the first vertically long lenticular lens, the second derivative at that time has a relative radius ρ of 0.55 to 0.55.
At the portion of 0.75, the value becomes particularly larger than the second derivative of the original cross-sectional shape.

Here, when the relative radius ρ is from 0.55 to 0.7
In the portion of No. 5, in the case of a longitudinally shaped lenticular lens having a large secondary differential value with respect to the secondary differential value of the cross-sectional shape in the case of the ellipse shown in FIG. When the relative radius ρ is in the range of 0.55 to 0.75, the curvature of the cross-sectional shape is steeper than the curvature in the case of an ellipse, and the focal length of the incident light beam is short. It turned out that a certain singular point is likely to occur.

Based on the above analysis results, in the present invention, the second derivative function of r of the above function Z (r) is represented by Z ″
(R), r of the elliptical function G (r) shown in FIG.
In the case where the secondary differential function of G ′ (r) is set to G ′ (r), the secondary differential function G ″
The condition regarding (r) was added.

Here, G (r) is given by Expression 5.

[0194]

(Equation 5)

However, the eccentricity e and constant a of the ellipse are as follows, where N is the refractive index, and T is the distance between the light incident surface and the light exit surface.
These are given by Equations 6 and 7, respectively.

[0196]

## EQU6 ## e = 1 / N

[0197]

[Mathematical formula-see original document] a = T / (1 + e) Now, conditions to be added to the second derivative function Z ″ (r) will be described.

When distortion of the type shown in FIG. 20 occurs, Z
The relative radius ρ at which the second derivative of (r) becomes large is 0.55
From 0.75 to 0.75 in the second derivative function Z ″ (r):
The condition of Equation 5 is newly added to the secondary differential function G ″ (r).

[0199]

0.85G ″ (r) ≦ Z ″ (r) ≦ 1.15
G ″ (r) When the lens shape is optimized under these conditions,
Even when distortion occurs, a singular point at which the viewing luminance sharply increases does not occur.

That is, when Z ″ (r) is larger than 1.15G ″ (r), when a maximum distortion of 0.01 mm occurs in the cross-sectional shape of the vertically long lenticular lens, the red and blue light are not observed. Singular points at which the luminance sharply increases occur near the viewing angles of −35 ° and 35 °, respectively.

When Z ″ (r) is smaller than 0.85G ″ (r), the color shift around a viewing angle of 30 ° becomes larger than that of a vertically long lenticular lens having an elliptical cross-sectional shape. The advantage of using a secondary aspheric surface is diminished.

In order to eliminate the cut-off, which is one of the problems of the conventional vertical lenticular lens having a cross-sectional shape of an ellipse with a shape satisfying the above conditions, a light beam incident on the vertical lenticular lens on the light emitting surface is required. It is effective not to squeeze in at one point, but to spread outward at the periphery of the incident light beam as shown in FIG. Therefore,
In the range where the relative radius ρ is 0.95 or more, the second derivative function Z ″
(R) adds a condition given by Expression 9 or Expression 10 to the secondary differential function G ″ (r).

[0203]

## EQU9 ## Z ″ (r) ≦ 0.6G ″ (r)

[0204]

[Mathematical formula-see original document] Z "(r) ≤Z" (0) By satisfying any one of these conditions, there is no cut-off, and the directional characteristics gradually decrease even when the viewing angle increases.

By optimizing the cross-sectional shape of the first vertically elongated lenticular lens so as to satisfy the above conditions, there was no cutoff, little color shift, and distortion occurred in the vertically elongated lenticular lens. Also in this case, it is possible to realize a transmission screen having no singular point of the viewing luminance.

The first lenticular lens on the light incident surface 31 of the second lenticular lens sheet 30 employs a vertically long lenticular lens having a high-order aspherical cross section having the above-mentioned characteristics.
The maximum cross-sectional shape of the first vertically long lenticular lens is 0.
Even when a distortion of 01 mm occurs, there is an effect that a singular point of the viewing luminance does not occur. In addition, compared to the conventional vertically long lenticular lens having an elliptical cross-sectional shape, it is possible to obtain a directional characteristic with less color shift, less cutoff, and less abrupt change in luminance.

Table 4 shows a fourth design example of the lens shape of the light entrance surface 31 and the light exit surface 32 of the second lenticular lens sheet 30.

[0208]

[Table 4]

FIG. 22 is a graph showing the second derivative of the cross-sectional shape when the horizontal cross-sectional shape of the first vertically long lenticular lens on the light incident surface 31 is the ellipse shown in FIG.
FIG. 9 is a characteristic diagram showing a comparison with a second derivative of a cross-sectional shape in the case of the design example in Table 4.

Assuming that the light-incident surface 31 of the second lenticular lens sheet 30 has a horizontal cross-sectional shape of the first vertically elongated lenticular lens, which is the aspheric surface of the design example in Table 4, the second derivative of the cross-sectional shape of the vertically elongated lenticular lens. The value satisfies the following conditional expression as shown in FIG.

That is, the second-order differential function Z ″ (r) relating to the aspherical surface is different from the second-order differential function G ″ (r) relating to the ellipse in that (1) the relative radius ρ is 0.55 ≦ ρ ≦ 0.75. In position

[0212]

0.85G ″ (r) ≦ Z ″ (r) ≦ 1.15
G ″ (r), and (2) the relative radius ρr is 0.95
≤ρ ≦ 1.0,

[0213]

The following expression is satisfied: Z ″ (r) ≦ 0.6G ″ (r)

FIG. 23 shows a screen screen of a transmission screen having a second lenticular lens sheet 30 in which the horizontal cross-sectional shape of the first vertically elongated lenticular lens on the light incident surface 31 is an aspheric surface of the design example in Table 4. FIG. 9 is a characteristic diagram showing calculated values of the directivity of light in the horizontal direction. Note that the concentration angle is 10 ° in FIG.

As shown in FIG. 23, in the horizontal directivity characteristics, the color shift at a viewing angle of 30 ° is 1.0 dB, which is smaller than that of a conventional vertically long lenticular lens having an elliptical cross-sectional shape. And there is no cutoff.

FIG. 24 shows the transmission when the distortion shown in FIG. 20 occurs in the first vertically elongated lenticular lens of the light incident surface 31 having an aspherical cross section in the design example of Table 4 described above. FIG. 6 is a characteristic diagram showing calculated values of horizontal directivity characteristics of the screen.

As shown in FIG. 23, according to the second lenticular lens sheet 30 in the fourth design example, there is no singular point at which the luminance sharply increases even when distortion occurs.

Table 5 shows a fifth design example of the lens shape of the light entrance surface 31 and the light exit surface 32 of the second lenticular lens sheet 30. This design example is also a design example in which even if a slight distortion occurs in the horizontal cross-sectional shape of the first vertically elongated lenticular lens on the light incident surface 31, similar to the fourth design example, the characteristic is hardly deteriorated. .

[0219]

[Table 5]

FIG. 25 shows the second derivative of the cross-sectional shape when the horizontal cross-sectional shape of the first vertically elongated lenticular lens on the light incident surface 31 is the ellipse shown in FIG.
FIG. 9 is a characteristic diagram showing a comparison with a second derivative of a cross-sectional shape in the case of the design example in Table 5.

Assuming that the light-incident surface 31 of the second lenticular lens sheet 30 has a horizontal cross-sectional shape of the first longitudinal lenticular lens, which is an aspheric surface in the design example shown in Table 5, the second derivative of the longitudinal lenticular lens has a sectional shape. The value satisfies the following conditional expression as shown in FIG.

That is, the second-order differential function Z ″ (r) relating to the aspherical surface is different from the second-order differential function G ″ (r) relating to the ellipse in that (1) the relative radius ρ is 0.55 ≦ ρ ≦ 0.75. In position

[0223]

0.85G ″ (r) ≦ Z ″ (r) ≦ 1.15
G ″ (r), and (2) the relative radius ρ is 0.95 ≦
At the position of ρ ≦ 1.0,

[0224]

The following equation is satisfied: Z ″ (r) ≦ Z ″ (0)

FIG. 26 shows a screen screen of a transmissive screen having a second lenticular lens sheet 30 in which the horizontal cross-sectional shape of the first vertically elongated lenticular lens on the light incident surface 31 is aspherical in the design example of Table 5. FIG. 9 is a characteristic diagram showing calculated values of the directivity of light in the horizontal direction. Note that the concentration angle is 10 ° in FIG.

As shown in FIG. 26, in the horizontal directivity characteristics, the color shift at a viewing angle of 30 ° is 2.0 dB, which is the same level of color shift as a conventional vertical lenticular lens having an elliptical cross section. , And has no cutoff.

Further, the color shift from the viewing angle of 0 ° to 50 ° is always 2.1 dB or less, and the color shift is small throughout the viewing angle range.

FIG. 27 shows the transmission when the distortion shown in FIG. 20 occurs in the first vertically elongated lenticular lens of the light incident surface 31 having the aspherical cross section in the design example of Table 5 described above. FIG. 6 is a characteristic diagram showing calculated values of horizontal directivity characteristics of the screen.

As shown in FIG. 27, according to the second lenticular lens sheet 30 in the fifth design example, there is no singular point at which the luminance sharply increases even when distortion occurs. Further, the color shift from the viewing angle of 0 ° to 50 ° is always 2.0
It is less than dB.

According to the transmission type screen using the second lenticular lens sheet 30 of the fifth design example,
Strongly resistant to distortion throughout the viewing angle range, there is no cutoff,
In addition, a directional characteristic with a small color shift can be obtained.

It goes without saying that the design example of the vertically elongated lenticular lens exemplified above can be applied to the second lenticular lens sheet 30 in each embodiment of the present invention described later.

The description of the design example of the vertically long lenticular lens of the second lenticular lens sheet 30 has been completed.
A design example of a horizontally long lenticular lens of 0 will be described.

First, technical means for increasing the vertical viewing angle β will be described with reference to FIG.

FIG. 28 is an explanatory diagram for explaining the function of diffusing the incident light beam 140 in the vertical direction of the screen screen by the lens function of the horizontally long lenticular lens on the light incident surface 21 of the first lenticular lens sheet 20.

FIG. 28 is a sectional view of the Fresnel lens sheet 10 according to an eighth embodiment described later. The diffusion of the light beam by the lens action of the horizontally long lenticular lens is exactly the same as that of the present embodiment. Therefore, the lens operation of the horizontally long lenticular lens on the light incident surface 21 of the first lenticular lens sheet 20 will be described with reference to FIG.

As shown in FIG. 28, each ray of the incident light beam 140 enters the lens surface S ₀ provided on the light incident surface 11 and is refracted, and then each focus (f ₁ , f _{1 in the} figure)
f ₀ ), and then diverges toward the lens surface S ₁ of the light exit surface 12 to diffuse the incident light flux as a whole.

Therefore, in order to provide such a diffusion function, in the present embodiment, the lens shape (convex toward the image light source) near the optical axes l and l 'is made to be a weak convex shape. Function (light collecting action) is weakened,
By increasing the convex shape as the distance from l 'increases, the lens function is enhanced.

In other words, in other words, compared to the focal length l ₀ due to the lens action near the optical axes l and l ', the optical axes l and l'
and to shorten the focal length l ₁ by the lens action of the portion remote from l '.

For example, the distance l ₀ and the distance l ₁ are

[0240]

It is preferable that the following condition is satisfied: l ₀ ≧ 2 · l ₁ .

At this time, the refracting power at the lens surface S ₀ provided on the light incident surface 11 becomes stronger as the distance from the optical axes l and l ′ increases, and the diffused light beam 141 passing through this portion becomes
Compared to the light beam 142 passing near l ′, the light beam is refracted more, and a wide vertical directional characteristic can be realized.

Table 6 shows the radius of curvature and aspherical coefficient, the surface spacing, the refractive index, and the effective radius in Equation 2 for the design example of the horizontally long lenticular lens on the light incident surface 21 of the first lenticular lens sheet 20. It is. The fact that the radius of curvature of the light exit surface 22 is ∞ indicates that the light exit surface 22 is flat.

[0243]

[Table 6]

FIG. 29 is a vertical sectional view showing a schematic shape of a design example of the horizontally long lenticular lens shown in Table 6.

FIG. 29 is a cross-sectional view of the Fresnel lens sheet 10 in an eighth embodiment described later. The diffusion of the light beam by the lens action of the horizontally long lenticular lens is exactly the same as that in the present embodiment. Therefore, the schematic shape of a design example of the horizontally long lenticular lens on the light incident surface 21 of the first lenticular lens sheet 20 will be described with reference to FIG.

In Table 6, the lens surface S of the light incident surface 21
_0, as shown in FIG. 29, a convex lenticular lens surface forming a convex to the image display source side, the radius of curvature is 0.105 mm, the light exit surface 22 from the lens surface S _0
1. The distance (surface interval) t on the optical axis up to the lens surface S1 is 2.
0 mm, indicating that the refractive index of the medium between them is 1.570.

When the sign of the radius of curvature is positive, it indicates that the center of curvature of the lens surface is located in a direction from the lens surface toward the light exit surface toward the light exit surface.

If the effective radius (P / 2) of the lens surface S ₀ is equal to 0.
Has become a 04mm, the number in the lens surfaces S ₀ 2
Is a radial distance r in the range of 0 ≦ r ≦ 0.04.
Is defined for

FIG. 30 is a diagram showing the directivity of the screen screen in the vertical direction according to the design example of the horizontally long lenticular lens shown in Table 6.

As shown in FIG. 30, in the vertical direction of the screen, an image can be viewed up to ± 68 ° vertically from the front of the screen. The direction in which the luminance becomes 50% of the luminance in the front direction of the screen is ± 10 ° vertically from the front direction of the screen.
, And practically sufficient performance has been obtained.

FIG. 31 shows a change in the lens action relating to the shape of the horizontally long lenticular lens on the light incident surface 21 of the first lenticular lens sheet 20, which is obtained by comparing the horizontally elongated lenticular lens of the transmission screen of the present embodiment with the transmission screen of the prior art. FIG. 3 is a characteristic diagram showing a comparison between the light incident surface 11 of the Fresnel lens sheet 10 and a horizontally long lenticular lens.

In FIG. 31, the vertical axis represents the second derivative of Z (r) of Equation 2 defining the shape of the horizontally long lenticular lens, and the horizontal axis represents the case where the lens effective radius P / 2 is used as a reference (1). , Relative value of the radial distance from the optical axis (relative radius)
It is. A solid line 1 indicates the characteristics of the conventional horizontally long lenticular lens, and a broken line 2 indicates the characteristics of the horizontally long lenticular lens corresponding to the lens shape data shown in Table 6. The alternate long and short dash line 3 will be described later.

As described above, the change in the lens action due to each position in the radial direction of the lens can be understood by observing the increase or decrease of the value of the second derivative. That is, in the horizontally long lenticular lens of the present embodiment, as shown by the broken line 2, the second derivative of the lens shape (convex toward the image light source) is represented by the optical axes l and l '.
, The sign increases as the sign remains positive. For this reason, the shape is such that the lens action is enhanced. On the other hand, in the conventional lens shape (convex toward the image light source), as shown by the solid line 1, although the second derivative is positive, the optical axes l and l '
The value does not increase even if you move away from it. For this reason, the shape is such that the lens action does not change.

In the transmission type screen of the present invention, the directional characteristic of light diffusion in the vertical direction of the screen by the horizontally long lenticular lens of the first lenticular lens sheet 20 is one of the factors that determine the intensity of moire generated on the screen. Become. According to the above-described design example of the horizontally long lenticular lens, the directional characteristics in the vertical direction of the screen screen are very good for reducing moiré. Hereinafter, this will be described.

The state of diffusion of projected image light by the horizontally long lenticular lens of the first lenticular lens sheet 20 is as shown in FIG.

That is, the light beam incident on the light incident surface 21 of the first lenticular lens sheet 20 is focused at the focal point in the first lenticular lens sheet 20 by the shape of the horizontally long lenticular lens on the light incident surface 21 as described above. Once converged, it then diverges and reaches the light exit surface 22. At this time, the image light corresponding to each pixel of the image source is diffused within a certain range.

The range of this diffusion is very wide, and the vertical directional characteristics are such that the skirt spreads out as shown in FIG. 30. By being added,
The distribution is as shown by the solid line 1 in FIG. In other words, in the vertical direction of the screen screen on the light emitting surface 22, even if a portion having a low relative luminance and a portion having a high relative luminance are alternately arranged to generate a bright and dark line causing moiré, the difference in luminance is very small. Therefore, the strength of moiré becomes very small.

As described above, in this embodiment, since the difference in luminance between the light and dark lines is reduced, moire can be significantly reduced.

In another embodiment of the present invention to be described later, by setting the cross-sectional shape of the horizontally long lenticular lens in the vertical direction of the screen to be the same as that of the present embodiment, a wide directivity is obtained as the directivity in the vertical direction of the screen. Needless to say, it is possible to realize a transmissive screen having characteristics, and to obtain the same effect as described above for reducing moiré.

As described above, in the present embodiment, the light diffusing material 6 in the base material of the second lenticular lens sheet 30 is eliminated, and the first lenticular lens sheet 20 having a small sheet thickness is newly constructed. In addition to improving the focus characteristics, brightness, and contrast of the image by making the shape of the light incident surface 11 of the Fresnel lens sheet 10 flat, as well as improving the directional characteristics of the screen screen in the horizontal direction and the vertical direction. This has the effect of being able to enlarge and further reduce moiré and color shift.

In this embodiment, the first lenticular lens sheet 20 shown in FIG.
In addition, although the configuration is such that a plurality of horizontally long lenticular lenses are arranged, the surface on which the horizontally long lenticular lenses are arranged is not limited to the light incident surface 21. Hereinafter, this will be described.

FIGS. 32 and 33 show the first lenticular lens sheet 20 of another configuration as the first lenticular lens sheet 20 of the transmissive screen 1 of the first and second modified examples of this embodiment, respectively. FIG. 2 is a perspective view showing a main part of the transmission screen 1 when using a screen.

The first lenticular lens sheet 20 of the first modification shown in FIG. 32 has a configuration in which a plurality of horizontally long lenticular lenses are arranged on the light emitting surface 22. Even with such a configuration, the same effect as that of the first lenticular lens sheet 20 shown in FIG. 1 can be obtained.

On the other hand, the first lenticular lens sheet 20 of the second modification shown in FIG. 33 has a configuration in which a plurality of horizontally long lenticular lenses are arranged on both the light incidence surface 21 and the light emission surface 22. Even with such a configuration, the first lenticular lens sheet 2 shown in FIG.
0, the light incident surface 21
Since there are horizontally long lenticular lenses on both sides of the light emitting surface 22 and the light emitting surface 22, there is an effect that the directivity in the vertical direction of the screen screen can be further expanded.

Further, in this embodiment, a plurality of convex lenticular lenses having a convex shape on the image source side are provided on the light incident surface 21 of the first lenticular lens sheet 20 shown in FIG. 1 as a horizontally long lenticular lens. Although they are arranged, the shape of the horizontally long lenticular lens is not limited to this. Hereinafter, this will be described.

FIGS. 34 and 35 show a light incident surface 21 as the first lenticular lens sheet 20 of the transmissive screen 1 of the third and fourth modifications of the present embodiment, respectively.
FIG. 4 is a perspective view showing a main part of the transmission screen 1 when a horizontally long lenticular lens of another shape is arranged as a horizontally long lenticular lens.

In the third modification shown in FIG. 34, a plurality of concave lenticular lenses having a concave shape on the image source side are arranged on the light incident surface 21 of the first lenticular lens sheet 20 as a horizontally long lenticular lens. ing. Even with such a shape, the same effect as that of the horizontally long lenticular lens having the shape shown in FIG. 1 can be obtained.

On the other hand, in the fourth modification shown in FIG. 35, the light incident surface 21 of the first lenticular lens sheet 20
Further, as a horizontally long lenticular lens, a plurality of convex lenticular lenses having a convex shape on the image generation source side and a plurality of concave lenticular lenses having a concave shape on the image generation source side are arranged alternately and continuously.

FIG. 36 is a sectional view showing a vertical section of the transmission screen 1 of FIG. 35, and 140 is an incident light beam.

As shown in FIG. 36, the incident light beam 140 incident on the Fresnel lens sheet 10 is refracted by the shape of the horizontally long lenticular lens on the light incident surface 21 of the first lenticular lens sheet 20 and diffuses in the direction perpendicular to the screen of the screen. After that, since the light is not diffused in the screen screen vertical direction, the width d in the screen screen vertical direction of the outgoing light beam with respect to the incident light beam 140 when viewed from the image viewing side is the transmission type of FIG. As in the case of the screen 1, the light is generally recognized by the width of the light beam appearing on the light exit surface 12 of the Fresnel lens sheet 10, and there is an effect that a good focus characteristic can be obtained.

In a horizontally long lenticular lens having a shape as shown in FIG. 35, in addition to the above-mentioned focus characteristics,
The same effect as that of the horizontally long lenticular lens having the shape shown in FIG. 1 can be obtained.

In addition, in the case of a horizontally long lenticular lens having a shape as shown in FIG. 35, when the radius of curvature of the horizontally long lenticular lens is reduced in order to expand the directivity in the vertical direction of the screen, the adjacent lenticular lens is not used. As the shape of the boundary between the lenses, the lens surfaces do not intersect at a sharp intersection angle. Therefore, when molding is performed by a molding die at the time of manufacturing, the shape of the above-described boundary of the horizontally long lenticular lens is almost perfect. And it has the effect of improving the screen formability. Hereinafter, this will be described.

FIG. 37 is a schematic sectional view showing a vertical section of the Fresnel lens sheet 10 in the conventional transmission screen and the first lenticular lens sheet 20 in the transmission screens of FIGS. 1 and 35.

In FIG. 37, (a) shows the Fresnel lens sheet 1 of the conventional transmission screen 1 shown in FIG.
0, (b) shows the first lenticular lens sheet 20 of the transmission screen 1 of the first embodiment shown in FIG.
(C) is a first lenticular lens sheet 2 of a fourth modification of the transmission screen of the first embodiment shown in FIG.
0 is shown respectively. In FIG. 37A, the Fresnel convex lens on the light exit surface 12 is omitted for simplicity.

The Fresnel lens sheet 10 of the conventional transmission screen 1 and the transmission screen 1 of the first embodiment.
In the first lenticular lens sheet 20 of
As shown in FIGS. 37A and 37B, only a convex lenticular lens having a convex shape on the image source side is used as a horizontally long lenticular lens of the light incident surface 11 or the light incident surface 21. Thus, a plurality of shapes are arranged. Among them, in the conventional transmission screen 1, as shown in FIG. 37A, the horizontally long lenticular lens has a large radius of curvature and a shape close to a plane.
On the other hand, in the transmission screen 1 of the first embodiment, FIG.
As shown in (b), depending on the design of the aspherical shape, the horizontally long lenticular lens has a small radius of curvature, and the shape of the boundary between adjacent lenticular lenses has a sharp intersection angle between lens surfaces. Moreover, the pitch of the horizontally long lenticular lens is 0.08 to 0.5.
When the horizontal lenticular lens having such a shape is to be molded by a molding die because it is as fine as about 1 mm, a portion corresponding to the boundary in the molding die is partially rounded. The lenticular lens is likely to be tinged or distorted. As a result, it is difficult to completely reproduce the shape of the above-described boundary portion of the horizontally long lenticular lens, and the formability of the screen may be deteriorated.

On the other hand, in the transmissive screen 1 of the fourth modification of the first embodiment, as shown in FIG. 37 (c), a convex lenticular lens having a convex shape on the image source side as a horizontally long lenticular lens. A lenticular lens and a concave lenticular lens forming a concave shape are used, and the two are alternately and continuously arranged in a plurality. Therefore, even if the radius of curvature of the horizontally long lenticular lens is reduced, the lens surfaces do not intersect at a sharp intersection angle as the shape of the boundary between adjacent lenticular lenses, and therefore, it is attempted to mold with a molding die. In this case, the shape of the above-described boundary portion of the horizontally long lenticular lens can be almost completely reproduced, and the screen has good moldability.

Further, if the radius of curvature of the horizontally long lenticular lens in the fourth modification is substantially the same as the radius of curvature of the horizontally long lenticular lens in the first embodiment, the transmission type screen 1 of the fourth modification will be described. The directivity of the screen screen in the vertical direction is substantially equal to that of the first embodiment.

FIG. 38 shows the directivity of the conventional transmissive screen 1, the transmissive screen 1 of the first embodiment, and the transmissive screen 1 of the fourth modification of the first embodiment in the vertical direction of the screen. Is a characteristic diagram schematically showing the vertical axis, the horizontal axis represents the vertical viewing angle, and the vertical axis represents the relative luminance.

In FIG. 38, A shows the directivity characteristics of the conventional transmission screen using the horizontal lenticular lens shown in FIG. 37A, and B shows the directivity characteristics using the horizontal lenticular lens shown in FIG. 37 shows the directional characteristics of the first embodiment and the directional characteristics of the fourth modified example using the horizontally long lenticular lens shown in FIG. Also, A
Is a directional characteristic when the light diffusing material in the base material of the lenticular lens sheet 30 'is temporarily eliminated.

That is, the directivity characteristics of the modification of the first embodiment using the horizontally long lenticular lens shown in FIG. 37C are the same as those of the first embodiment using the horizontally long lenticular lens shown in FIG. As with the directional characteristics, the directional characteristics are wide as shown in FIG.

When the pitch of the horizontally long lenticular lens of the first lenticular lens sheet 20 in the modification of the first embodiment is set so as to reduce moire, the pitch of the horizontally long lenticular lens is set as the pitch of the horizontally long lenticular lens. It is necessary to consider a pair of a convex lenticular lens having a convex shape on the image side and a concave lenticular lens having a concave shape on the image generation source side as one pitch.

Next, a description will be given of a design example of the first lenticular lens sheet 20 in a fourth modification of the first embodiment.

Table 7 shows a design example of a horizontally long lenticular lens on the light incident surface 21 of the first lenticular lens sheet 20. However, the horizontally long lenticular lens of the light incident surface 21 has a radius of curvature and a non-curvature of Equation 2 for each of a concave lenticular lens having a concave shape on the image display source side and a convex lenticular lens having a convex shape on the image display source side. The sphere coefficient and effective radius are shown. The light emitting surface 22 is a flat surface.

[0284]

[Table 7]

FIG. 39 is a sectional view showing a schematic shape of a design example of the horizontally long lenticular lens shown in Table 7.

In Table 7, the lens surface S of the light incident surface 21
_0, as shown in FIG. 39, a concave lenticular lens surface S ₀₁ forming a concave to the image display source side and a convex lenticular lens surface S ₀₂ that form a convex to the image display source side, a lens surface S each ₀₁ and the lens surface S ₀₂ of the curvature radius -0.
065625 mm and 0.065625 mm, the distance (surface interval) t on the optical axis from the lens surface S ₀₂ to the lens surface S ₁ of the light emitting surface 22 is 0.5 mm, and the refractive index of the medium between them is 1. 517 is shown.

The effective radius (P / 2) of both the lens surface S ₀₁ and the lens surface S ₀₂ is 0.025 mm,
In each of the lens surface S ₀₁ and the lens surface S ₀₂ , Z (r) of Expression 2 is a radial distance r in a range of 0 ≦ r ≦ 0.025.
Is defined for

FIG. 40 is a diagram showing diffusion of the incident light beam 140 in the vertical direction of the screen screen in the design example of the horizontally long lenticular lens shown in Table 7.

In this design example, the directional characteristics in the vertical direction of the screen screen are the directional characteristics shown in FIG. 30, as in the design example in Table 1 of the first embodiment.

In this design example, the shape of the convex lenticular lens and the concave lenticular lens as the horizontally long lenticular lens on the light incident surface 21 of the first lenticular lens sheet 20 is as shown in FIG. Although the shapes are symmetrical to each other, various other shapes can be considered as the shapes of the convex lenticular lens and the concave lenticular lens.

Table 8 shows a second design example of the first lenticular lens sheet 20.

[0292]

[Table 8]

[0293] In the design example of Table 8, the effective radius of the concave lenticular lens surface S ₀₁ forming a concave to the image display source side, convex lenticular lens surface forms a convex to the image display source side S
₀₂ is different from the design example in Table 7 in that the design is smaller than the effective radius of _{02 and} the radius of curvature of the convex lenticular lens is different from the radius of curvature of the concave lenticular lens. As in the design example of FIG. 7, the directivity characteristics are as shown in FIG.

Tables 9, 10 and 11 show still another design example of the horizontally long lenticular lens on the light incident surface 21 of the first lenticular lens sheet 20.
In these design examples, since the aspherical coefficients in Equation 2 are all 0, they are omitted from the table.

[0295]

[Table 9]

[0296]

[Table 10]

[0297]

[Table 11]

FIGS. 41, 42, and 43 are diagrams showing the directivity characteristics in the vertical direction of the screen screen according to the design examples of the horizontally long lenticular lenses shown in Tables 9, 10, and 11, respectively.

The directivity in the vertical direction of the screen screen according to these design examples is smaller than that of the design example of the horizontally long lenticular lens in Table 7, but has less footing, but has no practical problem. It is a standard.

Table 12 shows yet another design example of the horizontally long lenticular lens on the light incident surface 21 of the first lenticular lens sheet 20. In the present design example, since the aspherical coefficients in Equation 2 are all 0, they are omitted from the table. In this design example, a concave lenticular lens having a concave shape on the image display source side and a convex lenticular lens having a convex shape on the image display source side are provided.
Each combines two types of shapes.

[0301]

[Table 12]

FIG. 44 is a sectional view showing a schematic shape of a design example of the horizontally long lenticular lens shown in Table 12.

FIG. 45 is a diagram showing the diffusion of the incident light beam 140 in the vertical direction of the screen screen in the design example of the horizontally long lenticular lens shown in Table 12.

Also in this design example, the same directional characteristics in the vertical direction of the screen as in the design example of the horizontally long lenticular lens shown in Table 7 can be obtained.

Table 13 shows yet another design example of the horizontally long lenticular lens on the light incident surface 21 of the first lenticular lens sheet 20. In the design example of Table 13, in the state where the convex lenticular lens surface having a convex shape on the image display source side and the concave lenticular lens surface having a concave shape on the image display source side are continuous, a single expression in Equation 2 is used. Thus, the radius of curvature, the aspheric coefficient, and the like for the light incident surface S ₀ are collectively shown.

[0306]

[Table 13]

FIG. 46 is a sectional view showing a schematic shape of a design example of the horizontally long lenticular lens shown in Table 13.

FIG. 47 is a diagram showing diffusion of the incident light beam 140 in the vertical direction of the screen screen in the design example of the horizontally long lenticular lens shown in Table 13.

Also in this design example, the same directional characteristics in the vertical direction of the screen screen as in the design example of the horizontally long lenticular lens shown in Table 7 can be obtained.

As is clear from the above description, in each of the above-mentioned modifications of the first embodiment, the focus characteristics, brightness, contrast, and the formability of the screen are all improved, and the horizontal position of the screen is improved. direction,
In addition, there is an effect that the directivity in the vertical direction can be expanded.

On the other hand, in this embodiment, the light incident surface 21 of the first lenticular lens sheet 20 shown in FIG.
A horizontally long lenticular lens having a vertically asymmetric cross section may be adopted as the horizontally long lenticular lens. Hereinafter, the fifth modified example will be described.

[0312] In the rear projection type image display device, there are various positions where the viewer views the displayed image, and it is necessary that the entire screen looks bright when viewed from any position. The directional characteristics in the vertical direction of the screen screen required to satisfy this condition are not necessarily vertically symmetric with respect to the normal direction of the screen screen.

Table 14 is a table showing viewing angles at the center and upper and lower ends of the screen of the rear projection display from five representative positions among the viewing positions of the viewer. In the figure, the sign of the viewing direction is positive (+) when looking down from above the screen normal direction, and negative (-) when looking up from below.

[0314]

[Table 14]

In many cases, the viewer views the rear projection type image display apparatus while sitting on the floor or a chair, as shown in B, C and D in Table 14. Therefore, in the rear projection type display device according to the prior art, the directivity of the screen screen in the vertical direction is mainly adjusted so that the screen is brightest when viewed from these positions and the difference in brightness between the top and bottom of the screen is small. Was set.

Specifically, at the viewing positions of B and C, the viewing angles of the upper and lower screen screens are almost balanced.
In the viewing position, the viewing angle at the lower end of the screen is large, and the viewer feels slightly dark. Therefore, the directional characteristic is often shifted slightly upward (in FIG. 20, 5 °) from the viewing angle indicating the maximum luminance. As the means, there are two methods, a method of turning the projection direction of the projection lens upward and a method of eccentrically moving the center of the Fresnel lens sheet 10 upward, and any one of these methods, or By using both methods together, the above directional characteristics are provided.

However, even if such a measure is taken,
In the case of standing up and viewing (E in Table 14) or viewing in a recumbent state (A in Table 14), the phenomenon that the side of the screen where the viewing angle is large becomes dark does not improve. Therefore, in the prior art, the directional characteristics have been improved by increasing the amount of the light diffusing material 6 kneaded into the lenticular lens sheet 30 '. However, in general, when looking down from above (for example, when viewing from the viewing position E), the screen is viewed more closely than when looking up from below (for example, when viewing from the viewing position A). . At this time, the viewing angle at the lower end of the screen screen when looking down from above is larger than the viewing angle at the upper end of the screen screen when looking up from below. As mentioned above, since it is uniform up, down, left and right,
If the directional characteristics are expanded in accordance with the viewing angle at the lower end of the screen screen when looking down from above, the directional characteristics are unnecessarily widened below and the light utilization rate of the rear projection type image display device is reduced. There was a problem. Also, when the amount of the light diffusing material 6 is increased, the phenomenon that the screen shines white against external light becomes strong, and the contrast performance in a bright place is deteriorated. Furthermore, there are many problems such as difficulty in molding from the viewpoint of manufacturing.

In order to make the entire screen screen bright even when the transmission screen is viewed from various viewing positions, the cross-sectional shape of the horizontally long lenticular lens in this embodiment is changed. The shape is vertically asymmetric with respect to the center axis of the lens passing through the center, and light is diffused in the vertical direction of the screen by this horizontally long lenticular lens.

In this case, since the cross-sectional shape of the horizontally long lenticular lens is vertically asymmetric with respect to the lens center axis,
Light rays passing through this horizontally long lenticular lens are refracted at different angles in the upper and lower directions even if they pass through the same point from the lens center axis.
Vertically asymmetric directional characteristics can be obtained as the directional characteristics in the screen vertical direction.

Table 15 shows a design example of a horizontally long lenticular lens having a vertically asymmetric cross-sectional shape of the light incident surface 21 of the first lenticular lens sheet 20 in the transmissive screen 1 of the fifth modification of the present embodiment. , Number 2
2 shows the radius of curvature, aspheric coefficient, refractive index, and effective radius at. The light exit surface 22 is omitted from the table because it is a flat surface.

[0321]

[Table 15]

FIG. 48 is a cross-sectional view showing a schematic vertical cross-sectional shape of a design example of the horizontally long lenticular lens shown in Table 15.

In Table 15, the lens surface S ₀ of the light incident surface 21 is, as shown in FIG. 48, bounded by the position of the Z axis decentered above the lens center axis LL ′, and the upper lenticular lens surface S 0. _01, consists of a lenticular lens surface S ₀₂ of the lower, the radius of curvature of the lens surface S ₀₁ and the lens surface S ₀₁ is respectively 0.095 mm, a 0.100 mm, between the lens surface S ₀ to the light emitting surface 22 Medium has a refractive index of 1.
53 is shown.

[0324] effective radius respectively 0.045mm lens surface S ₀₁ and the lens surface S _02, has become a 0.055mm, the lens surface S _01, the lens surface S number at ₀₂ 2 Z
(R) is 0 ≦ r ≦ 0.045 and −0.05, respectively.
It is defined for a radial distance r in the range of 5 ≦ r ≦ 0. That is, in the horizontally long lenticular lens shown in FIG. 48, the width of the lens is 0.100 mm, and the sectional shape of the lens is 0.005 mm from the lens center axis LL '.
The upper and lower aspheric surfaces are formed with different Z-axis positions decentered upward by mm.

FIG. 49 is a characteristic diagram showing the directivity of the transmissive screen in the vertical direction of the screen when the horizontally long lenticular lens of FIG. 48 is used. Note that the viewing luminance in the drawing is a relative value with the luminance in the brightest direction (viewing angle) as 100%.

As shown in FIG. 49, the directivity in the vertical direction of the screen becomes an asymmetrical characteristic in the vertical direction in which the upper direction has a wider directivity than the lower direction. It has desirable directional characteristics. In the present embodiment, for simplicity, the viewing angle indicating the maximum luminance was set to 0 °, but the projection direction of the projection lens was set upward as described in the section of the related art, or the Fresnel lens of the Fresnel lens sheet was used. By decentering the center to the upper part of the screen, the viewing angle indicating the maximum luminance can be shifted upward from 0 °, but even in that case, the effect of the present invention is not affected at all.

Next, a description will be given of a second design example of a vertically asymmetric horizontal lenticular lens.

Table 16 shows the radius of curvature, the aspheric coefficient, the refractive index, and the effective radius of the second design example of the horizontally long lenticular lens having a vertically asymmetric cross-sectional shape.

[0329]

[Table 16]

FIG. 50 is a cross-sectional view showing a schematic vertical cross-sectional shape of a design example of the horizontally long lenticular lens shown in Table 16.

In the present design example, the width of the horizontally long lenticular lens is 0.1 mm, and the lenticular lens surface S ₀₁ above the Z axis decentered above the lens center axis LL ′.
If has a shape the same aspherical coefficients and the lenticular lens surface S ₀₂ of the lower side. That is, in a single aspherical shape that is vertically symmetric, the range in the radial direction r is set to −0.0515.
mm ≦ r ≦ 0.0485 mm, and the lens center axis LL ′
Has a shape shifted upward by 0.0015 mm.

In this case, the height of the lens surface at the boundary between the adjacent horizontal lenticular lens and the top of the lens becomes the upper side: 0.020 mm, the lower side: 0.025 mm. Since it is not connected to the lens, a substantially horizontal connecting surface 23 having a width of 0.005 mm is added to the upper end side of each horizontally long lenticular lens.

FIG. 51 is a characteristic diagram showing the directivity of the transmissive screen in the vertical direction of the screen when the horizontally long lenticular lens of FIG. 50 is used. Note that the viewing luminance in the figure is
This is a relative value when the luminance at the brightest viewing angle is 100%.

The directivity in the vertical direction of the screen shown in FIG. 51 is also vertically asymmetric, having a wider directivity in the upper direction than in the lower direction, as in the first design example of Table 15. .

The method of giving the shape of the horizontally long lenticular lens by one or two combinations of the aspherical expressions of Formula 1 has been described above. As disclosed below, the cross-sectional shape of the horizontally long lenticular lens is approximated by a polygon. By doing so, it is also possible to give the data as point sequence data.

A third design example of a vertically asymmetric horizontally long lenticular lens will be described below with reference to FIGS. 52 to 55.

FIG. 52 is a cross-sectional view showing a vertical cross section of the first lenticular lens sheet 20 in the third design example. The state of being refracted and emitted on the light exit surface 22 is shown as a ray tracing diagram. In FIG. 52, a plurality of horizontally long lenticular lenses are continuously formed on the light incident surface 21 of the first lenticular lens sheet 20, and the light emitting surface 22 is flat. 6, the coordinate axes are different from those in FIG. 6, and the upper end of one horizontally long lenticular lens is set as the origin of the Z axis and the R axis.

At this time, the cross-sectional shape of the horizontally long lenticular lens is defined as a polygonal shape formed by connecting straight lines at an angle of θ (n) with respect to the R axis when the projection length on the R axis is h (n). Approximate by the shape of Here, θ (n) is calculated as shown in FIG.
In the above, equal to the angle between the normal of the straight line and the Z axis,
When a ray parallel to the Z axis is incident, it is equal to the incident angle of the light. The number of straight lines constituting this horizontally long lenticular lens is m, and n is from the upper end of the horizontally long lenticular lens.
The number of the straight line is n. That is, n = 1 is a straight line at the upper end of the lenticular lens, and n = m
Corresponds to the straight line at the lower end of the lenticular lens. At this time, if m is, for example, 100 or more, the curve becomes practically almost smooth. Note that the width of one horizontal lenticular lens in the R-axis direction is H, and is represented by Expression 12.

[0339]

(Equation 12)

FIG. 53 is an enlarged view of the cross-sectional shape of the horizontally long lenticular lens of FIG. As can be seen from FIG. 53, the projection length d (n) of the n-th straight line on the Z-axis is
It is represented by 3.

[0341]

(Equation 13)

At this time, the R coordinate r (n) and the Z coordinate z (n) of the point at the lower end of the n-th straight line are represented by Equations 14 and 1, respectively.
5 is represented.

[0343]

[Equation 14]

[0344]

(Equation 15)

Therefore, the cross-sectional shape of the horizontally long lenticular lens of the present embodiment is represented by R coordinate and Z coordinate, and the upper end of the lenticular lens is defined as (0, 0), where (r (n), z (n)) , N = 1, 2, 3,
.., M).

Next, a method of designing the cross-sectional shape of the polygonal horizontally long lenticular lens will be described below.

As shown in FIG. 52, the width h (n) is incident on the n-th straight line of the horizontally long lenticular lens formed on the light incident surface 21 of the first lenticular lens sheet 20 at the angle of incidence θ (n). Light beam 143 parallel to the Z axis of
Is refracted so as to form an angle θ ′ (n) with the normal direction of the n-th straight line and to form an angle φ ′ (n) with the normal direction of the light exit surface 22, that is, the Z-axis direction. Emitted light beam 1 emitted from emission surface 22 in the direction of viewing angle φ (n)
It will be 44.

At this time, assuming that the refractive index of the base material 20B of the first lenticular lens sheet 20 is N, the relations of Expressions 16 and 17 are established from Snell's law.

[0349]

(Equation 16)

[0350]

[Equation 17]

On the other hand, from FIG. 52, θ (n), θ ′
Equation (18) exists between (n) and φ '(n).

[0352]

(Equation 18)

From these relationships, for a given φ (n), φ ′ (n), θ (n), and θ ′ (n) are obtained as shown in Equations 19, 20, and 21.

[0354]

[Equation 19]

[0355]

(Equation 20)

[0356]

(Equation 21)

Here, the outgoing light beam 144 outgoing in the minute angle range Δφ in the viewing angle direction of φ (n) is
The origin is a parallel light beam 143 having a width of h (n) on one side. Therefore, if the total luminous flux of the light entering one horizontal lenticular lens is Φ, the luminous flux s of the outgoing luminous flux 144
(N) is expressed as in Expression 22.

[0358]

(Equation 22)

In Equation 22, T (in) (n), T (out)
(N) is the transmittance on the light incident surface 21 and the light exit surface 22, respectively, and is given by Expressions 23 and 24.

[0360]

(Equation 23)

[0361]

(Equation 24)

Here, R (in, p) (n), R (in, s) (n),
R (out, p) (n) and R (out, s) (n) are the reflectance of p-polarized light and s-polarized light on the light incident surface 21 and the light exit surface 2 respectively.
2 is the reflectance of p-polarized light and s-polarized light, and is given by Equations 25, 26, 27, and 28.

[0363]

(Equation 25)

[0364]

[Equation 26]

[0365]

[Equation 27]

[0366]

[Equation 28]

Here, the light beam s (n) of the output light beam 144
Is obtained from the target directional characteristic in the vertical direction of the screen screen as follows.

FIG. 54 is a characteristic diagram showing the directivity of the transmission screen of this embodiment as a target in the vertical direction of the screen. In FIG. 54, the viewing luminance is a relative value when the luminance in the viewing direction in which the luminance is highest is 100%. The viewing angle φ (n) is the viewing angle φ shown in FIG.
In the directional characteristic shown in FIG. 54, the negative value when the angle range from the positive (+) side maximum viewing angle to the negative (−) side maximum viewing angle is divided into m equal parts. This is the n-th viewing angle from the maximum viewing angle on the (-) side. At this time,
The angle range Δφ of φ (n) is Δφ = (positive (+) side maximum viewing angle−negative (−) side maximum viewing angle) / m.

At this time, the viewing angle direction φ (n) shown in FIG.
Let L (n) be the luminance on the screen screen viewed from
The light beam s (n) of the output light beam 144 is expressed as shown in Expression 29.

[0370]

(Equation 29)

At this time, from Equations 22 and 29, h (n)
Is obtained as shown in Expression 30.

[0372]

[Equation 30]

Here, the width H in the R-axis direction of one horizontally long lenticular lens is expressed as in Expression 12 as described above.

Therefore, when the number of divisions m is sufficiently large, the total luminous flux Φ is obtained from Expression 30, and is approximately expressed by Expression 31.

[0375]

(Equation 31)

As is clear from the above calculations, if the luminance L (n) in the viewing angle direction φ (n) is sequentially given from n = 1 to m, θ (n) is obtained from Expressions 20 and 30.
And h (n) are obtained. Then, from Equations 14 and 15,
(R (n), z (n)) can be calculated, and a sequence of points representing the cross-sectional shape of the horizontally long lenticular lens as shown in FIG. 53 is obtained.

FIG. 55 is a cross-sectional view showing a vertical cross-sectional shape of a third design example of a horizontally long lenticular lens which is vertically asymmetrical. Light incident on the basis of the directional characteristics shown in FIG. The transmittance T (in) (n) on the surface 21 and the transmittance T (out) (n) on the light exit surface 22 are both 1
Here, an example in which the point sequence (r (n), z (n)) is approximately obtained is shown.

In this example, the width of the lens was 0.1 mm, and the refractive index was 1.53. Positive (+) of directional characteristics
Side maximum viewing angle 70 °, negative (-) side maximum viewing angle -50
The division number m was set to 120 with respect to °. Therefore Δφ is 1 °
It is.

In this case, the height of the lens surface at the boundary with the adjacent horizontally long lenticular lens is 0.018 mm at the upper side and 0.054 mm at the lower side with respect to the top of the lens, and it is not connected to the adjacent horizontally long lenticular lens as it is. Therefore, a substantially horizontal surface 23 having a width of 0.036 mm is added to the upper end side.

Since the sectional shape of the lenticular lens shown in FIG. 55 is directly calculated from the directional pattern shown in FIG. 54, the transmission type screen of this embodiment is arranged in the vertical direction shown in FIG. Asymmetric directional characteristics can be faithfully reproduced.

The calculation of the design of the horizontally long lenticular lens of the present embodiment can be easily made by a personal computer or the like. Therefore, the number m of viewing angles can be increased, and the angle range Δφ can be further reduced. It is possible to easily create a point sequence with the precision required for processing a lenticular lens during lens molding.

In this embodiment, for the sake of simplicity, for the sake of simplicity, the reflection loss of light on the light entrance surface 21 and the light exit surface 22 of the first lenticular lens sheet 20 and the absorption loss of light in the first lenticular lens sheet 20 To 0, and the transmittance T
Although (in) (n) and the transmittance T (out) (n) are both described as 1, it is needless to say that a more accurate lenticular lens shape can be realized by calculating these using Equations 23 and 24. Nor.

As described above, by using the method for designing the cross-sectional shape of the horizontally long lenticular lens in this embodiment,
The cross-sectional shape of a horizontally long lenticular lens, which was conventionally designed by trial and error, can be designed by direct calculation from the required directional characteristics, so that the cross-sectional shape of a horizontally long lenticular lens closer to the target directional characteristics can be obtained more easily. Become like

In the third design example described above, a method has been described in which the cross-sectional shape of the horizontally long lenticular lens is given as point sequence data by performing polygonal approximation. The cross-sectional shape
It is also possible to return to the aspherical shape of the curve as shown in Expression 2.

Hereinafter, a fourth design example of the vertically asymmetric horizontally long lenticular lens will be described with reference to FIGS.

FIG. 56 is a characteristic diagram showing the directivity of the transmission screen in the vertical direction of the screen screen in the present design example. In the directional characteristics shown in FIG. 56, the viewing angle φ is set so that the luminance in the viewing direction in which the luminance is the highest becomes slightly larger than the target directional characteristic in the third design example as an absolute value. (N) is ± 40
The viewing luminance in the vicinity of ° is slightly smaller than the target directional characteristic in the third design example. In FIG. 56, the viewing luminance is a relative value when the luminance in the viewing direction in which the luminance is highest is 100%.

FIG. 57 is a cross-sectional view showing the vertical cross-sectional shape of the horizontally long lenticular lens of the first lenticular lens sheet 20 used in the transmission screen of the fourth design example. The calculation method is the same as in the third design example. Using FIG. 5,
6, a point sequence (r (n),
z (n)) is obtained, and an example of a result obtained by regressing the cross-sectional shape of the horizontally long lenticular lens formed by the sequence of points into an aspherical shape having a curve represented by Formula 2 is shown. In the calculation of the point sequence, the transmittance T (in) (n) on the light incident surface 21 and the transmittance T (out) (n) on the light emitting surface 22 are both set to 1 and Δφ is 1 °. The number m of divisions is set to 115 for the positive (+) maximum viewing angle of 61 ° and the negative (−) maximum viewing angle of −54 ° of the directivity characteristic.

Table 17 shows the curvature radius, aspheric coefficient, refractive index, and effective radius in Equation 2 for the regression results of the above point sequence.

[0389]

[Table 17]

In Table 17, the lens surface S ₀ of the light incident surface 21 is, as shown in FIG. 57, bounded by the position of the Z axis decentered above the lens center axis LL ′, and the upper lenticular lens surface S 0. ₀₁ and a lower lenticular lens surface S ₀₂ , the curvature radii of both the lens surface S ₀₁ and the lens surface S ₀₂ are 0.085714 mm, and the lens surface S ₀
It is shown that the refractive index of the medium between the light and the light exit surface 22 is 1.517.

The effective radii of the lens surfaces S ₀₁ and S ₀₂ are 0.041429 mm and 0.058571 mm, respectively.
Is that Z (r) of Equation 2 on the lens surface S ₀₁ and the lens surface S ₀₂ is 0 ≦ r ≦ 0.0414, respectively.
29, -0.058571 ≦ r ≦ 0 in the range of radial direction r. That is, in the horizontally long lenticular lens shown in FIG. 57, the width of the lens is 0.100 mm, and the sectional shape of the lens is Z eccentric 0.008571 mm above the lens center axis LL '.
It is composed of different aspherical surfaces at the upper and lower sides of the axis.

FIG. 58 is a cross-sectional view showing a vertical cross-sectional shape of a modified example of the horizontally long lenticular lens of the fourth design example shown in FIG.

In the horizontally long lenticular lens shown in FIG. 58,
In the vertical cross-sectional shape of the horizontally long lenticular lens shown in FIG. 57, the shape of the lens surface is Z near the position of the Z axis.
Focusing on the fact that it is close to a plane that is almost perpendicular to the axis,
The shape is such that it is moved to the boundary between the adjacent horizontally long lenticular lenses and is replaced with a plane 24.

[0394] Specifically, the 0 ≦ r ≦ 0.004143 part of the range of 0 ≦ r ≦ 0.041429 upper lenticular lens surface S ₀₁ shown in Table 17, below the lenticular lens surface S ₀₂ -0.058571 r
A portion of -0.005857 ≦ r ≦ 0 in the range of 0 is deleted, and instead, a flat portion 24 having a width of 0.01 mm is provided at the boundary with the horizontally long lenticular lens. In this case, the upper lenticular lens surface S
Since there is already a nearly horizontal surface at the upper end of ₀₁ , it looks like a lenticular lens shape with a right angle cut.

In the horizontally long lenticular lens having the cross-sectional shape shown in FIG. 58, in addition to the same effects as those of the above-described respective design examples,
There is an effect that reflection of external light such as illumination light is reduced. Hereinafter, this will be described.

FIGS. 59 and 60 show that when the horizontal lenticular lens shown in FIGS. 57 and 58 is illuminated in a direction 45 ° to 60 ° above the normal direction of the screen, the illumination FIG. 4 is a ray tracing diagram when a light beam is reflected in a screen normal direction on a horizontally long lenticular lens surface of a first lenticular lens sheet of a transmission screen 1.

As shown in FIG. 59, in the horizontally long lenticular lens of FIG. 57, there is a light ray 145 that propagates inside the lens surface (on the medium side) while repeating total reflection on the lens surface. In the case of total reflection, there is almost no loss of light, so that the light 145 increases the brightness of the reflected light and lowers the contrast of the image.

On the other hand, in the horizontally long lenticular lens shown in FIG. 58, as shown in FIG. 60, a ray 146 propagating inside the lens surface (on the side of the medium) while repeating total reflection on the lens surface is emitted from the lenticular lens surface. Due to the right-angled cut shape, the light is once emitted into the air. In this case, a reflection loss always occurs when the light beam passes through the interface between the medium and the air, and when the light beam passes through the interface between the medium and the air, the light beam having a slightly different angle is cut into the above-mentioned right angle cut. Since the light is diffused at a larger angle when passing through the shape, the contribution of the luminance of the reflected light of the screen due to the light rays 146 is greatly reduced, so that there is an effect that high contrast performance can be obtained as image contrast.

In each of the above design examples, a configuration is adopted in which a horizontally long lenticular lens is provided on the light incident surface 21 of the first lenticular lens sheet 20. This horizontally long lenticular lens is a modification of the first embodiment shown in FIG. As an example, it may be provided on the light emitting surface 22 of the first lenticular lens sheet 20. Alternatively, as in a modified example shown in FIG. 33, the light-incident surface 21 and the light-emitting surface 22 may be provided on both surfaces. Also in these cases, there is an effect that a vertically asymmetric directional characteristic similar to the above-described design example can be obtained.

As is apparent from the above description, in the modification of the first embodiment using the horizontally long lenticular lens having a vertically asymmetric cross-sectional shape, it is possible to improve both the focus characteristic, brightness and contrast of an image. Thus, there is an effect that a vertically asymmetric directional characteristic can be obtained.

The horizontally long lenticular lens having a vertically asymmetric cross-sectional shape as shown in each of the above design examples is
This is suitable for obtaining a characteristic with a wide skirt in the directional characteristics in the vertical direction of the screen screen. In particular, the directional characteristic in the screen screen vertical direction is such that the maximum brightness is B ₀ and the brightness at each viewing angle in the screen screen vertical direction is 0.5 B _0.
As described above, when the viewing angle ranges that are 0.1B ₀ or more are respectively θ ₅₀ and θ ₁₀ ,

[0402]

32 is suitable for a transmissive screen for realizing a rear-projection image display device having a wide directional characteristic that satisfies the equation θ ₁₀ ≧ 3.4 × θ ₅₀ . However, the condition of Equation 31 can be realized in each embodiment of the present invention even in the case of a vertically symmetric directional characteristic.

The above description of a horizontally long lenticular lens having a vertically asymmetric cross-sectional shape has been mainly applied to a home-use single screen type rear projection type image display device having a diagonal of 35 to 70 inches. Specific examples have been described. In these design examples, as shown in Table 14, the design is such that the directional characteristics in the upward direction are more important than in the downward direction.

On the other hand, regarding the transmission type multi-screen used in the multi-screen rear projection type image display device for business use, the directivity in the vertical direction of the screen is not necessarily wide in the upward direction.

Here, as an application example of this embodiment, a horizontally long lenticular lens having a vertically asymmetric cross section is used.
A case where the present invention is applied to a transmission screen for a multi-screen rear projection type image display device will be described.

FIG. 61 is a cross-sectional view showing a schematic vertical cross section of a transmission screen of a two-stage multi-screen rear projection type image display device.

In the case of a transmissive screen having a two-stage structure as shown in FIG. 61, the biggest problem of the transmissive screen of the prior art is that the viewer has a large difference in the viewing angle between the upper and lower screens, and the upper side of the screen usually has the upper side. Since the screen is seen from the viewer, the lower screen is almost at or below eye level of the viewer, so if the vertical directional characteristics of the upper and lower screens are the same, Is that the brightness at the upper end or the lower end of the screen becomes dark.

Therefore, the cross-sectional shape of the horizontally long lenticular lens of the first lenticular lens sheet 20 of the upper transmissive screen 1A is made upside down to the above-described design example of the horizontally long lenticular lens having a vertically asymmetric cross-sectional shape. Shall be. Thereby, the diffused light 14 on the upper transmission screen 1A with respect to the incident light 140
Since 0 'is directed downward as a whole, it is possible to adopt a configuration in which the directional characteristics for the downward direction are emphasized.

Also, the cross-sectional shape of the horizontally long lenticular lens of the first lenticular lens sheet 20 of the lower transmission screen 1B is made the same as the design example of the above-described horizontally long lenticular lens having a vertically asymmetric cross-sectional shape. Thereby, the diffused light 140 ′ on the lower screen 1 </ b> B with respect to the incident light 140 is directed upward as a whole, so that it is possible to adopt a configuration in which importance is placed on the directional characteristics toward the upper side.

With this design, the directional characteristics in the vertical direction of the screen screen are such that the viewing angle is wider in the lower screen than in the upper screen, and is lower in the lower screen. The viewing angle is wider in the upper direction than in the upper direction, and there is an effect that the upper and lower screens having a two-stage configuration have a transmissive screen with almost no luminance step.

In the above description, the transmission type screen having a two-stage structure has been described. However, by individually optimizing the horizontally long lenticular lens used in each stage, a transmission screen having a two-stage structure or more can be obtained. The same effect can be obtained for the type screen.

Also, a horizontally long lenticular lens having a vertically asymmetric cross-sectional shape is designed to have an optimum shape in each of the embodiments described later, and is used for a transmission screen of a multi-stage multi-screen rear projection type image display device. It goes without saying that it can be applied.

Next, a second embodiment of the present invention will be described with reference to FIG.

FIG. 62 is a perspective view showing a main part of a transmission screen as a second embodiment of the present invention. The same parts as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

The difference between this embodiment and the first embodiment shown in FIG. 1 is that, in the first embodiment, as shown in FIG.
Light incident surface 21 of first lenticular lens sheet 20
Is a shape in which a plurality of horizontally long lenticular lenses having a longitudinal direction in the horizontal direction of the screen screen are arranged in the vertical direction of the screen screen. In the present embodiment, as shown in FIG. In addition to the light incident surface 21 of the lens sheet 20, the light incident surface 11 of the Fresnel lens sheet 10 has a shape in which a plurality of horizontally long lenticular lenses whose longitudinal direction is the horizontal direction of the screen screen are arranged in the vertical direction of the screen screen. It is in.

In this embodiment, light diffusion in the vertical direction of the screen is mainly performed by the horizontally long lenticular lens of the first lenticular lens sheet 20.
Light is diffused by the horizontally elongated lenticular lens of the Fresnel lens sheet 10 in an auxiliary manner. Further, both the first lenticular lens sheet 20 and the second lenticular lens sheet 30 have a configuration in which the base material does not contain a light diffusing material.

At this time, although the focus characteristic of the image is slightly reduced as compared with the first embodiment, the sheet thickness of the first lenticular lens sheet 20 is smaller than that of the conventional transmission screen, and Since both the first lenticular lens sheet 20 and the second lenticular lens sheet 30 do not contain the light diffusing material 6 in the base material, good focusing characteristics can be obtained.

The contrast and brightness of the image are the same as in the first embodiment.

Therefore, also in this embodiment, there is an effect that the focus characteristics, brightness and contrast of an image can be improved, and at the same time, the directional characteristics in the horizontal direction and the vertical direction of the screen can be enlarged.

Next, a third embodiment of the present invention will be described with reference to FIG.

FIG. 63 is a perspective view showing a main part of a transmission screen as a third embodiment of the present invention. The same parts as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

The difference between this embodiment and the first embodiment shown in FIG. 1 is that the shape of the first lenticular lens sheet 20 is different from that of the first embodiment as shown in FIG. The entrance surface 21 has a shape in which a plurality of horizontally long lenticular lenses having the longitudinal direction in the horizontal direction of the screen screen are arranged in the vertical direction of the screen screen. In the present embodiment, as shown in FIG. Numeral 21 is a Fresnel convex lens shape, and light emitting surface 22 has a shape in which a plurality of horizontally long lenticular lenses whose longitudinal direction is the horizontal direction of the screen screen are arranged in the vertical direction of the screen screen.

In this embodiment, the light diffusion in the vertical direction of the screen is controlled by the first lenticular lens sheet 2.
The configuration is performed by using a horizontally long lenticular lens of zero.
Further, both the first lenticular lens sheet 20 and the second lenticular lens sheet 30 have a configuration in which the light diffusing material 6 is not contained in the base material.

In this embodiment, as in the first embodiment, there is an effect that the focus characteristic, brightness and contrast of the image can be improved, and at the same time, the directivity in the vertical direction of the screen can be enlarged.

In this embodiment, the luminous flux of the red, green, and blue projected image light incident on the entire light incident surface 11 of the Fresnel lens sheet 10 is converted into a substantially parallel luminous flux for each color. First lenticular lens sheet 20
Is divided into a Fresnel convex lens on the light exit surface 12 of the Fresnel lens sheet 10 and a Fresnel convex lens on the light incident surface 21 of the first lenticular lens sheet 20. At this time, since the focal length of each Fresnel convex lens can be set to be longer than the focal length of the Fresnel convex lens in the first embodiment, the inclination of the lens surface of the Fresnel convex lens in the peripheral portion of the screen screen does not increase. The reflection loss of the image projection light in the peripheral portion is reduced, and the brightness of the image in the peripheral portion of the screen screen is improved.

Note that, instead of forming the light incident surface 21 of the first lenticular lens sheet 20 into a Fresnel convex lens shape, for example, the Fresnel lens sheet of the transmission type screen 1 in the first embodiment shown in FIG. The shape of the light incident surface 11 may be a Fresnel convex lens shape. Also in this case, the same effect as that of the present embodiment can be obtained.

In the first to third embodiments, the Fresnel lens sheet 10, the first lenticular lens sheet 20, and the second lenticular lens sheet 30 are all colorless and transparent. However, the second lenticular lens sheet 30 may be configured to be translucently colored.

In this case, the projected image light from the image generation source side to the image viewing side passes through the second lenticular lens sheet 30 only once, so that the amount of light is less than the transmittance of the second lenticular lens sheet 30. On the other hand, when external light such as illumination light is reflected by the transmissive screen and reaches the image viewing side, the light which becomes the most image-viewing side surface of the second lenticular lens sheet 30 is proportionally attenuated. Exit surface 32
Since the light passes through the second lenticular lens sheet 30 at least one round trip except for the light reflected by the light, the amount of light attenuates in proportion to the square of the transmittance of the second lenticular lens sheet 30. As a result, the outside light is
There is an effect that the ratio of the loss light is increased due to the absorption, and the contrast when external light such as illumination light is present is improved.

Further, with respect to the second lenticular lens sheet 30, the surface of the light emitting surface 32 on the image viewing side is particularly subjected to a treatment such as an antiglare treatment, an antistatic treatment, and a surface hardening treatment such as hard coating. May be applied. Typical examples of the anti-glare treatment include a method of providing fine irregularities on the entire surface and a method of providing the above-described optical antireflection film on the surface. When these anti-glare treatments are performed, there is an effect that reflection of an object on the viewer side or illumination light on the screen screen can be reduced. Further, when the antistatic treatment is performed, there is an effect that dust can be prevented from adhering due to charging of the surface of the second lenticular lens sheet 30. In addition, when surface hardening treatment is applied,
Even if any object collides from the viewer side, the surface of the second lenticular lens sheet 30 is less likely to be damaged.

Next, a fourth embodiment of the present invention will be described with reference to FIG.

FIG. 64 is a perspective view showing a main part of a transmission screen as a fourth embodiment of the present invention.

In FIG. 64, reference numeral 40 denotes a light absorbing sheet, and the Fresnel lens sheet 10, the first lenticular lens sheet 20, the second lenticular lens sheet 30, and the light absorbing sheet 40 each have end portions (not shown). Mutually fixed. Base material 40B of light absorbing sheet 40
Is made of a translucent colored thermoplastic resin material or a translucent colored glass plate. Reference numerals 41 and 42 denote a light incident surface and a light output surface of the light absorbing sheet 40, respectively, which are flat in this embodiment. Other parts that are the same as those in FIG. 1 are given the same reference numerals, and descriptions thereof are omitted.

The difference between this embodiment and the first embodiment shown in FIG. 1 is that a light absorbing sheet 40 is newly added as a component.

In this embodiment, the light absorbing sheet 40 is
The base material is made of a translucent colored thermoplastic resin material and has a function of absorbing more external light than projected image light.

That is, in the light absorbing sheet 40,
The projected image light from the image source side to the image viewing side passes through the light absorbing sheet 40 only once, so that the amount of light attenuates in proportion to the transmittance of the light absorbing sheet 40, When external light is reflected by the transmissive screen 1 and reaches the image viewing side, the light absorbing sheet 4 except for the light reflected by the light exit surface 42 of the light absorbing sheet 40 closest to the image viewing side.
0 at least one reciprocation, so that the light amount
It attenuates in proportion to the square of the transmittance of 0. As a result, external light is more absorbed than the projected image light, and the ratio of the loss light is increased, so that there is an effect that the contrast of the image when external light such as illumination light is present is improved.

Note that the transmittance of the light absorbing sheet 40 is 40% with respect to light rays having a wavelength of 400 nm to 700 nm.
It is preferable to have substantially the same transmittance in the range of about to 90%, but it is not limited to this.

Specific examples of the translucent colored thermoplastic resin material include the color tone N099 and N097 of an acrylic filter NG manufactured by Mitsubishi Rayon Co., Ltd.
FIG. 65 shows the transmittance characteristics of the acrylic filter NG for the light of each wavelength of the color tone N099, and FIG. 66 shows the transmittance characteristics of the acrylic filter NG for the light of each wavelength of the color tone N097. These translucent colored thermoplastic resin materials can also be used as the base material 30B of the second lenticular lens sheet 30 in the first to third embodiments.

Also in this embodiment, the light diffusion in the vertical direction of the screen screen is performed by the first lenticular lens sheet 2.
The configuration is performed by using a horizontally long lenticular lens of zero.
In addition, the first lenticular lens sheet 20, the second lenticular lens sheet 30, and the light absorbing sheet 40 have a configuration in which the light diffusing material 6 is not contained in the base material.

As a result, in this embodiment, as in the first embodiment, the focus characteristics, brightness, and contrast of the image are all improved, and the directional characteristics in the horizontal and vertical directions of the screen are enlarged. There is an effect that can be done.

On the other hand, also in this embodiment, the first, second,
In the same manner as in the third embodiment, the incident light beam 140 is applied to the light exit surface 3 by the first vertically long lenticular lens provided on the light entrance surface 31 of the second lenticular lens sheet 30.
There is a limitation on the sheet thickness of the second lenticular lens sheet 30 in order to design the lens to converge through the second second longitudinal lenticular lens.

This is the lenticular lens sheet 3 of the conventional transmission screen shown in FIGS. 106 and 107.
The same applies to 0 '. Therefore, in the conventional transmission screen, the sheet thickness of the Fresnel lens sheet 10 is adjusted to the lenticular lens sheet 30 'in order to secure the mechanical strength of the transmission screen 1 as a whole.
In general, it has been made thicker than the sheet thickness.

On the other hand, in this embodiment, FIG.
As shown in FIG. 3, the sheet thickness of the Fresnel lens sheet 10 is made thinner than that of the Fresnel lens sheet of the conventional transmission type screen so as to be substantially the same as the sheet thickness of the second lenticular lens sheet 30, while The thickness is the largest, and there is an effect that the mechanical strength of the transmission screen 1 as a whole is larger than that of the first embodiment shown in FIG.

Next, a fifth embodiment of the present invention will be described with reference to FIG.

FIG. 67 is a perspective view showing a main part of a transmission screen as a fifth embodiment of the present invention. The same parts as those in FIG. 64 are denoted by the same reference numerals, and description thereof will be omitted.

The difference between this embodiment and the fourth embodiment shown in FIG. 64 is that, in the fourth embodiment, as shown in FIG. 64, the light incident surface 21 of the first lenticular lens sheet 20 While the shape is a shape in which a plurality of horizontally long lenticular lenses whose longitudinal direction is the screen screen horizontal direction are arranged in the screen screen vertical direction, in the present embodiment, as shown in FIG. 67, the first lenticular lens In addition to the light incident surface 21 of the sheet 20, the shape of the light incident surface 11 of the Fresnel lens sheet 10 is such that a plurality of horizontally long lenticular lenses whose longitudinal direction is the screen screen horizontal direction are arranged in the screen screen vertical direction. is there.

In this embodiment, light diffusion in the vertical direction of the screen is mainly performed by the horizontally long lenticular lens of the first lenticular lens sheet 20.
Light is diffused by the horizontally elongated lenticular lens of the Fresnel lens sheet 10 in an auxiliary manner. In addition, the first lenticular lens sheet 20, the second lenticular lens sheet 30, and the light absorbing sheet 40 have a configuration in which the light diffusing material 6 is not contained in the base material.

At this time, although the focus characteristic of the image is slightly lowered as compared with the fourth embodiment, the sheet thickness of the first lenticular lens sheet 20 is smaller than that of the conventional transmission screen, and Since the first lenticular lens sheet 20, the second lenticular lens sheet 30, and the light absorbing sheet 40 do not contain the light diffusing material 6 in the base material, good focus characteristics can be obtained.

The brightness and contrast characteristics of the image are the same as in the fourth embodiment.

Therefore, also in this embodiment, there is an effect that the focus characteristics, brightness and contrast of an image can be improved, and at the same time, the directional characteristics in the horizontal and vertical directions of the screen can be enlarged.

Next, a sixth embodiment of the present invention will be described with reference to FIG.

FIG. 68 is a perspective view showing a main part of a transmission screen as a sixth embodiment of the present invention. The same parts as those in FIG. 64 are denoted by the same reference numerals, and description thereof will be omitted.

The difference between this embodiment and the fourth embodiment shown in FIG. 64 is that, in the fourth embodiment, as shown in FIG. 64, the light incident surface 21 of the first lenticular lens sheet 20 While the shape is such that a plurality of horizontally long lenticular lenses whose longitudinal direction is the screen screen horizontal direction are arranged in the screen screen vertical direction, in the present embodiment, as shown in FIG. 68, the first lenticular lens In addition to the light incident surface 21 of the sheet 20, a light absorbing sheet 40
The light incident surface 41 has a shape in which a plurality of horizontally long lenticular lenses whose longitudinal direction is the horizontal direction of the screen screen are arranged in the vertical direction of the screen screen.

In this embodiment, the light diffusion in the vertical direction of the screen screen is controlled by the first lenticular lens sheet 2.
0 horizontal lenticular lens and light absorbing sheet 40
Is performed by dispersing with a horizontally long lenticular lens. Also, the first lenticular lens sheet 20,
Both the second lenticular lens sheet 30 and the light absorbing sheet 40 have a configuration in which the light diffusing material 6 is not contained in the base material.

In this embodiment, in order to enlarge the directivity of the screen screen in the vertical direction, even if the radius of curvature of the horizontally long lenticular lens of the light absorbing sheet 40 is reduced,
As in the case where the radius of curvature of the horizontally long lenticular lens of the first lenticular lens sheet 20 in the first embodiment shown in FIG. 1 is reduced, the focus characteristic does not deteriorate.

[0455] This is because the vertically long lenticular lens on the light incident surface 31 of the second lenticular lens sheet 30 and the horizontally long lenticular lens on the light incident surface 41 of the light absorbing sheet 40 are arranged close to each other. Depending on. That is, in this embodiment, since the start point of the light diffusion of the incident light beam in the horizontal direction of the screen screen and the start point of the light diffusion in the vertical direction of the screen screen are close to each other, the focus characteristic does not deteriorate.

The image brightness is the same as in the fourth embodiment.

On the other hand, in the present embodiment, the reflected light from the horizontal lenticular lens of the light incident surface 41 of the light absorbing sheet 40 toward the screen front with respect to the external light is shown in FIG.
4 and the fifth embodiment shown in FIG. 67, the image contrast is lower than in the fourth and fifth embodiments. However, in this embodiment, the contrast is further improved by providing a fine uneven shape or providing an optical antireflection film on the entire surface of the light incident surface 41 of the light absorbing sheet 40 and performing an antiglare treatment. Can be compensated.

Therefore, also in this embodiment, there is an effect that both the focus characteristic, the brightness and the contrast of the image can be improved, and the directional characteristics in the horizontal and vertical directions of the screen screen can be enlarged.

Next, a seventh embodiment of the present invention will be described with reference to FIG.

FIG. 69 is a perspective view showing a main part of a transmission screen as a seventh embodiment of the present invention. The same parts as those in FIGS. 67 and 68 are denoted by the same reference numerals and description thereof will be omitted. .

The difference between this embodiment and the sixth embodiment shown in FIG. 68 is that, in the sixth embodiment, as shown in FIG. 68, the light incident surface 21 of the first lenticular lens sheet 20 And the shape of the light incident surface 41 of the light absorbing sheet 40 is a shape in which a plurality of horizontally long lenticular lenses having the longitudinal direction in the horizontal direction of the screen screen are arranged in the vertical direction of the screen screen. Is
As shown in FIG. 69, the light incident surface 21 of the first lenticular lens sheet 20 and the light incident surface 4 of the light absorbing sheet 40
In addition to 1, the shape of the light incident surface 11 of the Fresnel lens sheet 10 is such that a plurality of horizontally long lenticular lenses whose longitudinal direction is the horizontal direction of the screen screen are arranged in the vertical direction of the screen screen.

In this embodiment, the light diffusion in the vertical direction of the screen is mainly performed by dispersing the light with the horizontal lenticular lens of the first lenticular lens sheet 20 and the horizontal lenticular lens of the light absorbing sheet 40. The light is diffused supplementarily by ten horizontally long lenticular lenses. Also,
Each of the first lenticular lens sheet 20, the second lenticular lens sheet 30, and the light absorbing sheet 40 does not include the light diffusing material 6 in the base material.

At this time, although the focus characteristic of the image is slightly lowered as compared with the sixth embodiment, the sheet thickness of the first lenticular lens sheet 20 is smaller than that of the conventional transmission screen, and Since the first lenticular lens sheet 20, the second lenticular lens sheet 30, and the light absorbing sheet 40 do not contain the light diffusing material 6 in the base material, good focus characteristics can be obtained.

The brightness and contrast characteristics of the image are the same as in the sixth embodiment.

Therefore, also in the present embodiment, there is an effect that the focus characteristics, brightness and contrast of an image can be improved, and at the same time, the directional characteristics in the horizontal and vertical directions on the screen can be enlarged.

In the transmissive screens of the fifth to seventh embodiments, the Fresnel lens sheet 1
0, the horizontal lenticular lens of the first lenticular lens sheet 20, and the horizontal lenticular lens of the second lenticular lens sheet 30, all of which have a convex lenticular lens convex toward the image source side in the vertical direction of the screen. The shape of these horizontally long lenticular lenses is convex toward the image source side, like the shape of the horizontally long lenticular lenses of the first lenticular lens sheet 20 shown in FIG. A plurality of convex lenticular lenses having a shape and concave lenticular lenses having a concave shape on the image source side may be alternately and continuously arranged in the vertical direction of the screen.

In this case, light diffusion in the vertical direction of the screen screen is mainly performed, and the first lenticular lens sheet 20 is used.
When the light is diffused by another horizontal lenticular lens and the light is supplementarily diffused by another horizontal lenticular lens,
As for the horizontal lenticular lens that diffuses light auxiliary, only the convex lenticular lens that is convex toward the image source side is used as the screen screen, similar to the horizontal lenticular lens on the light incident surface of the Fresnel lens sheet of the conventional transmission screen. It may be configured to be arranged in the vertical direction. This is because the lenticular lens that diffuses light supplementarily has a shape closer to a flat surface and has less problems in screen formability.

On the other hand, in the fourth to seventh embodiments, the ghost caused by the unnecessary reflection of the projection image light in the Fresnel lens on the light emitting surface 12 of the Fresnel lens sheet 10 becomes less noticeable. Hereinafter, this will be described.

FIG. 70 is a cross-sectional view showing a vertical cross section of the Fresnel lens sheet 10 in the conventional transmissive screen 1 of FIGS. 106 and 107, and in the transmissive screen 1 of the fourth embodiment of the present invention in FIG. .

In FIG. 70, (a) shows FIG. 106, FIG.
07 shows the Fresnel lens sheet 10 of the conventional transmission screen 1 and FIG. 64B shows the Fresnel lens sheet 10 of the transmission screen shown in FIG. In FIG. 70A, for simplicity, a horizontally long lenticular lens on the light incident surface 11 is omitted.

In general, in the Fresnel lens sheet 10,
As shown in FIGS. 70 (a) and 70 (b), most of the rays of the incident light beam 147 become outgoing rays 148, but some of the rays are reflected by the light exit surface 12 and further reflected by the light entrance surface 11. The ghost ray 1 is partially reflected and reaches the light exit surface 12
49.

At this time, in the conventional transmissive screen Fresnel lens sheet 10, as shown in FIG. 70 (a), since the sheet thickness is large, the distance R between the original image position and the ghost position is considerably large. It grows large and ghosts become very noticeable. On the other hand, in the Fresnel lens sheet 2 of each of the fourth to seventh embodiments described above, FIG.
As shown in FIG. 2B, since the sheet thickness is small, the position of the original image and the position of the ghost are close to each other, and the distance R is reduced, so that the ghost becomes inconspicuous.

In addition, making the sheet thickness of the Fresnel lens sheet 10 thinner than that of the Fresnel lens sheet of the conventional transmission type screen and making it about the same as the sheet thickness of the second lenticular lens sheet 30 can simultaneously improve the image focus. There is also an effect of improving characteristics.

Next, an eighth embodiment of the present invention will be described with reference to FIG.

FIG. 71 is a perspective view showing a main part of a transmission screen as an eighth embodiment of the present invention. The same parts as those in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted.

The transmissive screen 1 of this embodiment has a two-piece structure including a Fresnel lens sheet 10 and a second lenticular lens sheet 30. On the light incident surface 11 of the Fresnel lens sheet 10, a plurality of horizontally long lenticular lenses having the longitudinal direction in the horizontal direction of the screen screen are formed in the vertical direction of the screen screen. A Fresnel convex lens is formed. The second lenticular lens sheet 30 has the same configuration as the second lenticular lens sheet 30 shown in each of the above embodiments.

Table 18 shows the radius of curvature and aspherical coefficient, the surface spacing, the refractive index, and the effective radius in Equation 2 for a design example of the horizontally long lenticular lens on the light incident surface 11 of the Fresnel lens sheet 10.

[0478]

[Table 18]

[0479] In Table 18, the fact that the radius of curvature of the light exit surface 22 is -410.74 indicates that the radius of curvature of the Fresnel convex lens on the light exit surface 22 is 410.74 mm.

The directional characteristics in the vertical direction of the screen screen according to the design example of the horizontally long lenticular lens shown in Table 18 are shown in FIG.
Are almost the same as the directivity characteristics shown in FIG.

In the transmission screen of this embodiment,
As in the above embodiments, the brightness and the contrast of the image can be both improved, and the directional characteristics in the horizontal and vertical directions of the screen can be expanded, and the color shift can be reduced.

FIG. 72 is a modification of the transmission screen of the eighth embodiment. As in the case of the fourth embodiment shown in FIG. 64, the thickness of the Fresnel lens sheet 10 is changed to the second thickness. Of the lenticular lens sheet 30 of FIG.

In the transmissive screen 1 shown in FIG. 72, similarly to the transmissive screen 1 shown in FIG. 71, the brightness and the contrast of the image are both improved, and the directional characteristics in the horizontal and vertical directions of the screen are changed. In addition to the effect of reducing the color shift, the horizontal lenticular lens on the light incident surface 11 of the Fresnel lens sheet 10 and the first vertical lenticular lens sheet on the light incident surface 31 of the second lenticular lens sheet 30 Are arranged so as to be close to each other, so that there is an effect that the focus characteristic of the image is improved. Further, similarly to the transmission screen 1 of the fourth embodiment shown in FIG.
Since the sheet thickness is small, the ghost caused by unnecessary reflection of the projected image light in the Fresnel convex lens on the light emitting surface 12 is less noticeable.

In this embodiment, the Fresnel lens sheet 10
In the figure, the sheet thickness along the optical axis of the horizontally long lenticular lens between the lens surface of the horizontally long lenticular lens on the light incident surface 11 and the light exit surface 12 is defined as t _1, and the second lenticular lens sheet 30 Incident surface 31
Between the first vertical lenticular lens and the second vertical lenticular lens of the light emitting surface 32, the sheet thickness along the optical axis of the first or second vertical lenticular lens when the t ₂ of the sheet Thickness t ₁ and t ₂

[0485]

It is preferable to satisfy the condition of t ₁ ≦ 2.5t ₂ , but it is not limited to this.

In this embodiment, FIGS. 71 and 7
The Fresnel lens sheet 10 shown in FIG.
Although a plurality of horizontally long lenticular lenses are arranged, the surface on which the horizontally long lenticular lenses are arranged is not limited to the light incident surface 11.

In the modification of this embodiment shown in FIG. 73, the Fresnel lens sheet 10 has a light emitting surface 12 having a shape in which a plurality of horizontally long lenticular lenses are arranged, and a light incident surface 11 having a Fresnel convex lens shape. The configuration is as follows.

FIG. 74 is a graph showing the directivity in the vertical direction of the screen screen when the configuration of the light entrance surface 11 and the light exit surface 12 is changed in the design example of the Fresnel lens sheet 10 shown in Table 18. FIG.

As shown in FIG. 74, the vertical viewing angle β is ± 4
Images on the screen can be viewed over a wide range of 5 degrees. In addition, the vertical viewing angle β, which is the most important 50% luminance in practical use (relative value to the maximum luminance obtained when the viewing position of the screen is arbitrarily changed in the vertical direction) is ± 10 degrees, which is sufficient for practical use. It has gained.

In the modification of the embodiment shown in FIG. 73, the characteristic of the change of the lens action related to the shape of the light emitting surface 12 of the Fresnel lens sheet 10 is different from the characteristic shown by the broken line 2 in FIG. Is a characteristic that is axially symmetric with respect to the central axis.

In addition, in the transmission screen 1 having the configuration shown in FIG. 73, the same effects as those of the transmission screen 1 of the eighth embodiment shown in FIG. 72 can be obtained.

Also, in the eighth embodiment, as the horizontally long lenticular lens of the Fresnel lens sheet 10,
A horizontally long lenticular lens having a shape as shown in FIGS. 34 and 35 may be arranged.

FIG. 75 shows a Fresnel lens sheet 10 of a transmissive screen 1 according to a modification of the eighth embodiment, in which the light incident surface 11 has a convex shape having a convex shape on the image source side as in FIG. It is a perspective view which shows the principal part of the transmission type screen 1 at the time of arrange | positioning the lenticular lens and the concave lenticular lens which forms a concave shape by the side of an image generation source in the shape which arranged alternately continuously a plurality of horizontally long lenticular lenses. .

FIG. 76 is a sectional view showing a vertical section of the transmission screen 1 of FIG. 75, and 140 is an incident light beam.

As shown in FIG. 76, the incident light beam 140 incident on the Fresnel lens sheet 10 is refracted by the shape of the horizontally long lenticular lens on the light incident surface 11 and is diffused in the vertical direction of the screen screen. Since the light passes through the lenticular lens sheet 30 as it is and is not diffused in the screen screen vertical direction, the width d in the screen screen vertical direction of the outgoing light beam with respect to the incident light beam 140 when viewed from the image viewing side is the aforementioned As in the case of the first embodiment, the light beam is generally recognized by the width of the light beam appearing on the light exit surface 12 of the Fresnel lens sheet 10, and there is an effect that a good focus characteristic can be obtained.

The brightness, contrast, and screen formability of the image are the same as in the modification of the first embodiment shown in FIG.

Therefore, also in the present embodiment, there is an effect that both the focus characteristic, brightness, contrast, and the formability of the screen can be improved, and the directional characteristics in the horizontal direction and the vertical direction of the screen can be expanded.

Also, in the transmission type screen having the structure shown in FIG. 75, the ghost caused by the unnecessary reflection of the projected image light in the Fresnel lens on the light emitting surface 12 of the Fresnel lens sheet 10 becomes inconspicuous. Hereinafter, this will be described.

FIG. 77 is a cross-sectional view showing a vertical cross section of the Fresnel lens sheet 10 in the conventional transmission screen shown in FIG. 107 and the transmission screen shown in FIG.

In FIG. 77, (a) shows the Fresnel lens sheet 1 of the conventional transmission screen 1 shown in FIG.
0, and (b) shows the Fresnel lens sheet 10 of the transmission screen shown in FIG. 75, respectively.

As in the case of FIG. 70, generally, in the Fresnel lens sheet 10, as shown in FIGS. 77 (a) and (b), most of the light of the incident light flux 147 is outgoing light 148.
However, some light rays are reflected by the light exit surface 12, further partially reflected by the light incident surface 11, and
And becomes a ghost ray 149.

At this time, in the Fresnel lens sheet 10 of the conventional transmission screen, as shown in FIG. 77 (a), since the sheet thickness is large, the distance R between the original image position and the ghost position is considerably large. It grows large and ghosts become very noticeable. On the other hand, in the Fresnel lens sheet 10 of the transmission screen 1 having the configuration of FIG.
As shown in FIG. 7B, since the sheet thickness is thin, the original image position and the ghost position are close to each other, and the distance R is reduced, so that the ghost becomes inconspicuous.

In the transmission type screen having the structure shown in FIG. 75, the shape of the convex lenticular lens and the concave lenticular lens in the horizontally long lenticular lens of the light incident surface 11 of the Fresnel lens sheet 10 is the same as that of the first embodiment. Various shapes such as those shown in the design examples of Tables 7 to 13 can be considered.

FIG. 78 is a sectional view showing another specific example of the Fresnel lens sheet 10 in the transmission screen 1 of FIG.

FIG. 78A shows an example in which the radius of curvature of the convex lenticular lens is different from the radius of curvature of the concave lenticular lens. (B) shows an example in which both the convex lenticular lens and the concave lenticular lens are asymmetric in the screen screen vertical direction. In the case of the example shown in FIG. 78B, there is an effect that the directional characteristics in the vertical direction of the screen screen can be designed to be vertically asymmetric.

In the eighth embodiment, both the Fresnel lens sheet 10 and the second lenticular lens sheet 30 are colorless and transparent.
For, as in the first to third embodiments,
It may be configured to be translucent.

In this case, there is an effect that the contrast when external light such as illumination light is present is improved.

Further, with respect to the second lenticular lens sheet 30, similarly to the first to third embodiments, the surface of the light exit surface 32 on the image viewing side is subjected to an antiglare treatment and an antistatic treatment. Alternatively, a treatment such as a surface hardening treatment such as hard coating may be performed. When the anti-glare processing is performed, there is an effect that reflection of an object on the viewer side or illumination light on the screen screen can be reduced. Further, when the antistatic treatment is performed, there is an effect that dust can be prevented from adhering due to charging of the surface of the second lenticular lens sheet 30. Further, when the surface hardening treatment is performed, there is an effect that the surface of the second lenticular lens sheet 30 is less likely to be damaged even if some object collides from the viewer side.

Next, a ninth embodiment of the present invention will be described with reference to FIG.

FIG. 79 is a perspective view showing a main part of a transmission screen as a ninth embodiment of the present invention.

In FIG. 79, reference numeral 40 denotes a light absorbing sheet, and the Fresnel lens sheet 10, the second lenticular lens sheet 30, and the light absorbing sheet 40 are fixed to each other at ends (not shown). 40B is a base material of the light absorbing sheet 40, and is made of a translucent colored thermoplastic resin material or a translucent colored glass plate. 4
Reference numerals 1 and 42 denote a light incident surface and a light output surface of the light absorbing sheet 40, respectively, which are flat in this embodiment. Other parts that are the same as those shown in FIG. 71 are given the same reference numerals, and descriptions thereof will be omitted.

The difference between this embodiment and the eighth embodiment shown in FIG. 71 is that, similar to the fourth embodiment shown in FIG. 64, a light absorbing sheet 40 is newly added as a component. is there.

[0513] The light absorbing sheet 40 is made of a thermoplastic resin material whose base material is translucently colored and has a function of absorbing more external light than the projected image light. There is an effect that the contrast of the image when there is is improved.

Also in this embodiment, the light diffusion in the vertical direction of the screen is performed by the horizontally long lenticular lens of the Fresnel lens sheet 10. Further, both the second lenticular lens sheet 30 and the light absorbing sheet 40 have a configuration in which the light diffusing material 6 is not contained in the base material.

As a result, in the present embodiment, as in the fourth embodiment, the focus characteristics, brightness, contrast, and screen formability of the image are all improved, and the horizontal and vertical directions of the screen are changed. This has the effect of expanding the directional characteristics of.

[0516] On the other hand, in this embodiment, similarly to the above embodiments, the incident light beam 140 is emitted by the first vertically long lenticular lens provided on the light incident surface 31 of the second lenticular lens sheet 30. There is a limit to the sheet thickness of the second lenticular lens sheet 30 so that the design is such that it converges through the second longitudinal lenticular lens of the exit surface 32.

This is the lenticular lens sheet 3 of the conventional transmission screen shown in FIGS. 106 and 107.
The same applies to 0 '. Therefore, in the conventional transmission screen, in order to secure the mechanical strength of the transmission screen 1 as a whole, the sheet thickness of the Fresnel lens sheet 10 is set to the lenticular lens sheet 30 ′.
In general, the sheet thickness is made larger than the sheet thickness.

On the other hand, in this embodiment, FIG.
As shown in FIG. 3, the sheet thickness of the Fresnel lens sheet 10 is made smaller than that of the Fresnel lens sheet of the conventional transmission type screen so as to be substantially the same as the sheet thickness of the second lenticular lens sheet 30, while the sheet of the light absorbing sheet 40 is formed. Since the thickness is the largest, the mechanical strength of the transmissive screen 1 as a whole is greater than that of the eighth embodiment shown in FIG.

Further, the horizontally long lenticular lens on the light incident surface 11 of the Fresnel lens sheet 10 and the first vertically long lenticular lens sheet on the light incident surface 31 of the second lenticular lens sheet 30 are arranged close to each other. Therefore, there is an effect that the focus characteristic of the image is improved. Further, similarly to the transmissive screen 1 having the configuration shown in FIG. 72, since the sheet thickness of the Fresnel lens sheet 10 is small, ghost caused by unnecessary reflection of projected image light in the Fresnel convex lens on the light emitting surface 12 is reduced. This has the effect of making it less noticeable.

In FIG. 79, the shape of the horizontally long lenticular lens on the light incident surface 11 of the Fresnel lens sheet 10 is different between a convex lenticular lens having a convex shape on the image source side and a concave shape having a concave shape on the image source side. The lenticular lens has a shape in which a plurality of lenticular lenses are arranged alternately and continuously. However, the present invention is not limited to this, and a horizontally long lenticular lens having various shapes as exemplified in the above-described embodiments may be used.

Next, a tenth embodiment of the present invention will be described with reference to FIG.

FIG. 80 is a perspective view showing a main part of a transmission screen as a tenth embodiment of the present invention. The same parts as those in FIG. 79 are denoted by the same reference numerals, and description thereof will be omitted.

The difference between this embodiment and the ninth embodiment shown in FIG. 79 is that, in the ninth embodiment, only the light incident surface 11 of the Fresnel lens sheet 10 has a shape as shown in FIG. While a plurality of horizontally long lenticular lenses whose longitudinal direction is the screen screen horizontal direction are arranged in the screen screen vertical direction, in the present embodiment, as shown in FIG. In addition to the surface 11, similar to the sixth embodiment shown in FIG.
The light incident surface 41 of the light absorbing sheet 40 also has a shape in which a plurality of horizontally long lenticular lenses whose longitudinal direction is the horizontal direction of the screen screen are arranged in the vertical direction of the screen screen.

In this embodiment, the light diffusion in the vertical direction of the screen screen is performed by the horizontal lenticular lens on the light incident surface 11 of the Fresnel lens sheet 10 and the light absorbing sheet 40.
Of the light incidence surface 41 of the horizontal lenticular lens. Further, both the second lenticular lens sheet 30 and the light absorbing sheet 40 have the light diffusing material 6 in the base material.
Is not contained.

In this embodiment, the vertically long lenticular lens on the light incident surface 31 of the second lenticular lens sheet 30 and the horizontally long lenticular lens on the light incident surface 41 of the light absorbing sheet 40 are arranged close to each other. Therefore, even if the radius of curvature of the horizontally long lenticular lens of the light absorbing sheet 40 is reduced in order to enlarge the directional characteristics in the vertical direction of the screen screen, the focus characteristics do not deteriorate.

The brightness of the image is the same as in the ninth embodiment.

[0527] On the other hand, in this embodiment, the reflected light toward the front of the screen of the horizontally long lenticular lens on the light incident surface 41 of the light absorbing sheet 40 with respect to external light is shown in FIG.
Since the contrast is higher than in the ninth embodiment shown in FIG. 9, the image contrast is lower than in the ninth embodiment. However, in this embodiment, the contrast is further improved by providing a fine uneven shape or providing an optical antireflection film on the entire surface of the light incident surface 41 of the light absorbing sheet 40 and performing an antiglare treatment. Can be compensated.

Therefore, also in the present embodiment, there is an effect that both the focus characteristic, the brightness and the contrast of the image can be improved, and the directional characteristics in the horizontal and vertical directions of the screen screen can be expanded.

In this embodiment as well, various shapes can be adopted as the shape of the horizontally long lenticular lens.

FIG. 81 is a perspective view showing a main part of a transmissive screen as a modification of the present embodiment. The same parts as those in FIG. 80 are denoted by the same reference numerals, and description thereof will be omitted.

In the transmissive screen 1 shown in FIG. 81, both the light incident surface 11 of the Fresnel lens sheet 10 and the light incident surface 41 of the light absorbing sheet 40 are convex lenticular lenses which are convex toward the image generation source side. The lenticular lens has a shape in which a plurality of lenticular lenses and a concave lenticular lens having a concave shape on the image generation source side are alternately and continuously arranged in the vertical direction of the screen screen.

In this embodiment, the focus characteristics, brightness, contrast, and formability of the screen are all improved, and the directional characteristics in the horizontal and vertical directions of the screen are enlarged.

In this embodiment, the light diffusion in the vertical direction of the screen is mainly performed by the horizontally long lenticular lens of the Fresnel lens sheet 10 or the horizontally long lenticular lens of the light absorbing sheet 40, and the other lenticular lens assists the diffusion. In the case of performing light diffusion, the lenticular lens that performs auxiliary light diffusion has a convex shape that is convex toward the image generation source side, similarly to the horizontally long lenticular lens of the light incident surface of the Fresnel lens sheet of the conventional transmission screen. A configuration in which only the lenticular lens is arranged in the vertical direction of the screen screen may be adopted. This is because the lenticular lens that diffuses light supplementarily has a shape closer to a flat surface and has less problems in screen formability.

Next, an eleventh embodiment of the present invention will be described with reference to FIG.

FIG. 82 is a perspective view showing a main part of a transmission screen as an eleventh embodiment of the present invention. The same parts as those in FIG. 80 are denoted by the same reference numerals, and description thereof will be omitted.

The difference between this embodiment and the tenth embodiment shown in FIG. 80 is that, in the tenth embodiment, as shown in FIG. 80, the light incident surface 11 of the Fresnel lens sheet 10 and the light absorbing sheet The light incident surface 41 has a shape in which a plurality of horizontally long lenticular lenses whose longitudinal directions are in the horizontal direction of the screen screen are arranged in a vertical direction of the screen screen. As described above, only the light incident surface 41 of the light absorbing sheet 40 has a shape in which a plurality of horizontally long lenticular lenses whose longitudinal direction is the horizontal direction of the screen screen are arranged in the vertical direction of the screen screen.

[0537] In this embodiment, the light diffusion in the vertical direction of the screen screen is performed by a horizontally long lenticular lens on the light incident surface 41 of the light absorbing sheet 40. Also,
The second lenticular lens sheet 30 has a configuration that hardly contains a light diffusing material in the base material.

Now, the shape of the horizontally long lenticular lens on the light incident surface 41 of the light absorbing sheet 40 will be described in detail below.

First, technical means for enlarging the vertical viewing angle β will be described with reference to FIG.

FIG. 83 shows the light absorbing sheet 40 in FIG.
3 is an enlarged view of a portion C (a cross section in the vertical direction of the screen).

In FIG. 83, the horizontally elongated lenticular lens on the light incident surface 41 of the light absorbing sheet 40 emits light from the second lenticular lens sheet 30 and
Has a function of diffusing a light beam incident on the light incident surface 41 in the direction perpendicular to the screen. This is based on the phenomenon that, even if the incident light beam is the same scanning line or the light beam of the same pixel, the incident angle differs depending on the incident position on the light incident surface 41, so that the light beam is refracted at a different angle.

That is, each light beam of the incident light beam enters the horizontally long lenticular lens of the light incident surface 41 and is refracted. Then, each light beam is condensed at each focal point. Will be diffused throughout.

Therefore, in order to have such a diffusion function, in the present embodiment, the lens shape (convex toward the image light source side; condensing action) near the optical axes l and l 'is made a weak convex shape. Accordingly, the lens function is weakened, and the lens function is increased by forming the shape such that the convex shape becomes stronger as the distance from the optical axes l and l 'increases.

That is to say, in other words, the focal length due to the lens action at a portion distant from the optical axes l and l 'is shorter than the focal length due to the lens action near the optical axes l and l'. For this reason, the refracting power of the light incident surface 41 in the horizontally long lenticular lens increases as the distance from the optical axes l and l 'increases, and the light flux passing through this portion is smaller than the light flux passing near the optical axes l and l'. As a result, the light is refracted more, and a wide vertical directional characteristic can be realized.

The above principle is the same as the case of the horizontally long lenticular lens of the first lenticular lens sheet 20 in the embodiment of FIG. 1 described above.

[0546] Table 19 shows a design example of the horizontally long lenticular lens of the light absorbing sheet 40. In Table 19, the radius of curvature of the light exit surface is denoted by ∞,
Is a flat surface.

[0547]

[Table 19]

FIG. 84 is a characteristic diagram showing the directivity of the transmission screen having the light absorbing sheet 40 according to the design example in Table 19 in the vertical direction of the screen.

As shown in FIG. 84, the vertical viewing angle β is ± 7
Images on the screen can be viewed in a very wide range of 4 degrees. Further, the vertical viewing angle β which is the most important 50% luminance in practical use (relative value to the maximum luminance obtained when the viewing position of the screen is arbitrarily changed in the vertical direction) is ± 10.
It has obtained sufficient performance for practical use.

Next, a change in the lens action regarding the shape of the light incident surface of the light absorbing sheet 40 will be described with reference to FIG.

In FIG. 31, the vertical axis represents the light absorbing sheet 40.
Is a value obtained by substituting the distance in the radial direction into a function obtained by secondarily differentiating Equation 2 defining the shape of the light incident surface, and the horizontal axis represents the relative distance (relative radius) in the radial direction to the lens effective radius P / 2. . The solid line 1 shows the characteristics of the conventional screen, and the dashed line 3 shows the characteristics of the screen corresponding to the lens shape data shown in Table 19. Note that the broken line 2 has already been described.

As described above, the change in the lens action at each position in the radial direction of the lens can be determined by observing the increase or decrease of the value obtained by the second-order differentiation. That is, as shown by the alternate long and short dash line 3, the shape of the lens on the entrance surface of this embodiment becomes positive as the second-order differential value moves away from the optical axes l and l '. Therefore, the shape is such that the lens action (convex toward the image light source side) is enhanced. On the other hand, in the conventional lens shape, as shown by the solid line 1, although the second derivative is positive, the optical axes l and l '
The value does not increase even if you move away from it. For this reason, the shape is such that the lens action (convex toward the image light source) does not change.

At this time, the light incident surface 4 of the light absorbing sheet 40
1 is close to the light exit surface 32 of the second lenticular lens sheet 30, and the start point of light diffusion of the incident light beam 140 in the horizontal direction of the screen screen and the start point of light diffusion in the vertical direction of the screen screen are close to each other. As a result, the focus characteristics do not deteriorate.

In the present embodiment, when there is external light such as illumination light, the reflected light from the horizontal lenticular lens of the light incident surface 41 of the light absorbing sheet 40 toward the screen front direction with respect to the external light is shown in FIG. This is more than in the case of the ninth embodiment shown, and the contrast of the image is reduced. However, also in this embodiment, similarly to the tenth embodiment shown in FIG. 80, a fine unevenness is provided on the entire surface of the light incident surface 41 of the light absorbing sheet 40, or an optical antireflection film is provided. By performing anti-glare processing such as the above, contrast can be compensated.

Therefore, also in the present embodiment, there is an effect that the focus characteristics, brightness, contrast, and formability of the image are all improved, and the directional characteristics in the horizontal and vertical directions of the screen are enlarged.

Also in this embodiment, various shapes can be adopted as the shape of the horizontally long lenticular lens.

FIG. 85 is a perspective view showing a main part of a transmissive screen as a modification of the present embodiment. The same parts as those in FIG. 82 are denoted by the same reference numerals, and description thereof will be omitted.

In the transmissive screen 1 shown in FIG. 85, the shape of the horizontally long lenticular lens on the light incident surface 41 of the light absorbing sheet 40 is the same as in FIG. 81, and the convex lenticular has a convex shape toward the image source. The lens has a shape in which a plurality of lenses and a concave lenticular lens having a concave shape on the image generation source side are alternately and continuously arranged in the vertical direction of the screen screen.

FIG. 86 is a sectional view showing a vertical section of the transmissive screen 1 of FIG. 85, and 140 is an incident light beam.

In the transmission screen 1 having the structure shown in FIG. 85, the base material 3 of the second lenticular lens sheet 30 is used.
86B, the light diffusing material 6 is not dispersed, and as shown in FIG. 86, the incident light beam 140 incident on the Fresnel lens sheet 10 is not diffused in the vertical direction of the screen screen, and And the second lenticular lens sheet 30 and the light absorbing sheet 40
Is diffused in the vertical direction of the screen screen by the shape of the horizontally long lenticular lens for the first time on the light incident surface 41, so that the width d in the vertical direction of the screen screen with respect to the incident light beam 140 when viewed from the image viewing side is approximately Recognition is made based on the width of the light beam appearing on the light exit surface 32 of the second lenticular lens sheet 30, and good focus characteristics are obtained.

At this time, the light incident surface 4 of the light absorbing sheet 40
1 is close to the light exit surface 32 of the second lenticular lens sheet 30, and the start point of light diffusion of the incident light beam 140 in the horizontal direction of the screen screen and the start point of light diffusion in the vertical direction of the screen screen are close to each other. As a result, the focus characteristics do not deteriorate.

Even with such a configuration, there are effects that the focus characteristics, brightness, contrast, and formability of the screen are all improved, and the directional characteristics in the horizontal and vertical directions of the screen are enlarged.

In this embodiment, FIGS. 82 and 85
Has a configuration in which a plurality of horizontally long lenticular lenses are arranged on the light incident surface 41, but the surface on which the horizontally long lenticular lenses are arranged is not limited to the light incident surface 41. A configuration in which a plurality of horizontally long lenticular lenses are arranged on the emission surface 42 may also be used.

In the transmission screen 1 of the eleventh embodiment shown in FIG. 82, the light incident surface 41 of the light absorbing sheet 40
When the light exit surface 42 is reversed, each light beam of the incident light beam passes through the Fresnel lens sheet 10 and the second lenticular lens sheet 30 and enters the light incident surface 41 of the light absorbing sheet 40, and the light exit surface 42 Head to the horizontal lenticular lens surface. As described above, the lens function of the horizontally long lenticular lens surface of the light exit surface 42 is weakened by making the lens shape (convex toward the image viewing side) near the optical axes l and l 'weak. By increasing the convex shape as the distance from the optical axes l and l 'increases, the lens function is enhanced. For this reason, the refracting power of the horizontally long lenticular lens becomes stronger as the distance from the optical axes l and l 'increases, and the light flux passing through this portion is refracted more greatly than the light flux passing near the optical axes l and l'. , Wide vertical directional characteristics can be realized.

FIG. 87 shows the light absorbing sheet 4 shown in Table 19.
FIG. 10 is a characteristic diagram showing directivity characteristics in a vertical direction of a screen screen when the configuration of the light incident surface 41 and the light exit surface 42 is changed in the design example of No. 0;

As shown in FIG. 87, the vertical viewing angle β is ± 4
Images on the screen can be viewed in a wide range of 4 degrees. The vertical viewing angle β, which is the most important 50% luminance in practical use (relative value to the maximum luminance obtained when the viewing position of the screen is arbitrarily changed in the vertical direction) is ± 10 degrees, which is sufficient for practical use. Have gained.

Also, the light absorbing sheet 40 in this embodiment is used.
The characteristic of the change of the lens action of the horizontally long lenticular lens of the light exit surface 42 is such that the characteristic is axially symmetric about the horizontal axis with respect to the characteristic shown by the dashed line 3 in FIG.

As described above, also in this embodiment, the same effect as the transmissive screen shown in FIG. 82 can be obtained.

Next, a twelfth embodiment of the present invention will be described.

FIG. 88 is a perspective view showing a main part of a transmission screen as a twelfth embodiment of the present invention.

In FIG. 88, the transmission screen 1 is
Fresnel lens sheet 10, micro lens sheet 50
This is a two-sheet configuration. The Fresnel lens sheet 10 and the micro lens sheet 50 are fixed to each other at an end (not shown). Reference numerals 10B and 50B denote base materials of the Fresnel lens sheet 10 and the micro lens sheet 50, respectively, each of which is made of a substantially transparent thermoplastic resin material.

[0572] Light incident surface 11 of Fresnel lens sheet 10
Is flat in this embodiment, and the light emitting surface 12 has a Fresnel convex lens shape.

Reference numeral 51 denotes a light incident surface of the microlens sheet 50, which has a shape in which microlens elements are continuously arranged in the horizontal and vertical directions of the screen. 5
Reference numeral 2 denotes a light exit surface of the microlens sheet 50, which has a shape in which microlens elements are substantially opposed to the microlens elements on the light incident surface 51 and are continuously arranged in the horizontal and vertical directions of the screen. . Further, a convex projection 52P is provided at a boundary portion between the microlens elements on the light emitting surface 52, and a light absorbing layer 53 having a finite width is provided thereon.

That is, this embodiment is different from the eighth embodiment shown in FIG. 71 in that the light incident surface 11 of the Fresnel lens sheet 10 is flat, and the light incident surface 11 is replaced with the second lenticular lens sheet 30. Surface 51 and light emitting surface 5
The microlens sheet 50 having microlens elements is added to FIG. 2 as a new component.

In the present embodiment, the microlens element provided on the light incident surface 51 of the microlens sheet 50 is the same as the horizontal lenticular lens provided on the light incident surface 11 of the Fresnel lens sheet 10 in the eighth embodiment. This is an alternative to the first vertically elongated lenticular lens provided on the light incident surface 31 of the second lenticular lens sheet 30.

That is, the microlens element on the light incident surface 51 of the microlens sheet 50 has the same shape in the horizontal section of the screen as that of the first vertically long lenticular lens shown in FIG. The shape is the same as the shape of the horizontally long lenticular lens shown in FIG.

Therefore, in this embodiment, the same effect as that of the eighth embodiment shown in FIG. 71 can be obtained.

In the first to third embodiments and the eighth embodiment, all of the Fresnel lens sheet 10, the first lenticular lens sheet 20, and the second lenticular lens sheet 30 are light diffusing. Although the material 6 is not included, the first lenticular lens sheet 20 and the second lenticular lens sheet 3
A very small amount of the light diffusing material 6 may be dispersed in one or two of the zeros to assist the light diffusion. In the fourth to seventh embodiments and the ninth to eleventh embodiments, the Fresnel lens sheet 10, the first lenticular lens sheet 20, the second lenticular lens sheet 30, the light absorbing sheet 40, the light diffusion material 6 is not included, but one of the first lenticular lens sheet 20, the second lenticular lens sheet 30, and the light absorbing sheet 40, or 2
A very small amount of the light diffusing material 6 may be dispersed in one or all three sheets to assist the light diffusion. In these cases,
As long as the light diffusion by the light diffusion material 6 is auxiliary,
Even if the directional characteristics in the screen screen vertical direction are enlarged, the focus characteristics and contrast of the image are improved, and an effect similar to the case without the light diffusing material 6 is obtained. An example will be described below.

FIG. 89 shows the eleventh embodiment shown in FIG. 82 in which a small amount of the light diffusing material 6 is mixed into the inside of the base material 30B of the second lenticular lens sheet 30. Is the same as

In this case, the second lenticular lens sheet 30 is a lenticular lens sheet 3 of the prior art.
Unlike 0 ', it has only a small amount of light diffusing material. Therefore, the incident light on the light incident surface 31 is hardly scattered by the light diffusing material 6 before reaching the light emitting surface 32 to generate stray light. Since the light is hardly scattered by the diffusion material 6, the contrast of the image is remarkably improved as compared with the conventional screen, and the focus characteristic is hardly deteriorated by the light diffusion material.

In the above case, in the transmissive screen, the contribution of the light diffusing material and the horizontally long lenticular lens in the directivity of the screen screen in the vertical direction may be designed separately. For example, in the directional characteristics in the screen screen vertical direction, the light diffusion material may mainly perform light diffusion in the vicinity of the screen front, and the horizontally long lenticular lens may mainly perform light diffusion in a direction away from the screen front. Also in this case, as long as the amount of the light diffusing material is small, the same effects as those of the above-described embodiments can be obtained, and the cross-sectional shape of the horizontally long lenticular lens becomes a shape with a relatively small sag amount, and the moldability during manufacturing is reduced. The effect is improved.

Next, a thirteenth embodiment of the present invention will be described.

FIG. 90 is a perspective view showing a main part of a transmission screen as a thirteenth embodiment of the present invention. The same parts as those in FIG. 71 are denoted by the same reference numerals, and description thereof will be omitted.

The transmissive screen 1 of this embodiment has a two-sheet structure including a Fresnel lens sheet 10 and a second lenticular lens sheet 30.

The difference between this embodiment and the eighth embodiment shown in FIG. 71 is that, in the eighth embodiment, as shown in FIG. 71, the horizontally long lenticular lens of the light incident surface 11 of the Fresnel lens sheet 10 is used. In this embodiment, the light is diffused in the vertical direction of the screen screen, whereas in the present embodiment, the base material 3 of the second lenticular lens sheet 30 is used.
0B, a small amount of the light diffusing material 6 is mixed in, and light diffusion in the vertical direction of the screen is performed entirely by the light diffusing material 6,
The point is that the horizontally long lenticular lens on the light incident surface 11 of the Fresnel lens sheet 10 is eliminated. However, the amount of the light diffusing material 6 is smaller than that of the vertically long lenticular lens sheet in the conventional transmission screen shown in FIG.

The first vertically elongated lenticular lens on the light incident surface 31 of the second lenticular lens sheet 30 has a higher-order aspherical cross section, and its second derivative is
The conditional expression described in the fourth or fifth design example in the first embodiment is satisfied. That is, the second derivative function Z ″ (x) relating to the aspherical surface satisfies Equations 8 and 9 or the second derivative function G ″ (x) relating to the ellipse or Equations 8 and 10 I have.

In this embodiment, since the aspherical horizontal lenticular lens employed in each of the above embodiments is not used for light diffusion in the vertical direction of the screen screen, the directivity in the vertical direction of the screen screen is low. However, the directional characteristics in the horizontal direction of the screen screen are characterized by adding the diffusion characteristics of the light diffusing material 6 to the directional characteristics described in the first embodiment. In other words, the distribution of the viewing luminance of the directional characteristics becomes gradual, the singularity of the viewing luminance becomes inconspicuous, and the maximum luminance when viewed from the front of the screen decreases. The relative viewing brightness at an angle will increase. As a result, even if a distortion occurs in the cross-sectional shape of the vertically long lenticular lens, there is an effect that occurrence of a singular point of viewing luminance and an increase in color shift can be reduced to some extent.

The transmissive screen 1 of this embodiment has an effect that the color shift is small and the deterioration of the directivity characteristic with respect to the distortion generated at the time of manufacture is similar to the transmissive screen of each embodiment described above.

If the amount of the light diffusing material 6 is increased, problems such as deterioration of contrast, reduction of light utilization rate, and difficulty in molding occur. However, in the transmission screen of this embodiment,
Since it is possible to obtain directional characteristics with little sudden change in luminance, the light diffusing material 6 can be obtained from the lenticular lens sheet 30 'in the conventional transmission screen shown in FIG.
Can be reduced, and the above-mentioned problems are less likely to occur.

Incidentally, in each of the above embodiments, any one of the Fresnel lens sheet 10, the first lenticular lens sheet 20, the second lenticular lens sheet 30, the light absorbing sheet 40, and the micro lens sheet 50 has an anti-reflection surface. A film may be provided. In this case, the contrast of the image itself can be improved. Hereinafter, a transmission type screen provided with such an anti-reflection film will be described as an application example of each of the above embodiments with reference to FIGS.

FIGS. 91 and 92 are perspective views each showing a main part of a transmission screen as an application example of the eighth embodiment.

In the application example of FIG. 91, an anti-reflection film 111 is provided on the light incident surface 11 of the Fresnel lens sheet 10 disposed closest to the image generation source side. By doing so, stray light inside the set can be reduced, and there is an effect of improving image contrast.

In the application example of FIG. 92, an anti-reflection film 311 is provided on the light incident surface 31 of the second lenticular lens sheet 30 disposed closest to the image viewing side.
By doing so, the Fresnel lens sheet 10
Stray light generated by multiple reflections between the second lenticular lens sheet 30 and the second lenticular lens sheet 30, and there is an effect that the contrast of an image is greatly improved.

In addition, for example, in the transmission type screen having the first lenticular lens sheet 20 as a constituent element as in the first embodiment, the light entrance surface 21 and the light exit surface 22 of the first lenticular lens sheet 20 are provided. May be provided with an antireflection film. By doing so, stray light generated by multiple reflections between the Fresnel lens sheet 10, the first lenticular lens sheet 20, and the second lenticular lens sheet 30 can be reduced, and there is an effect that image contrast is greatly improved. .

As a specific method of providing an anti-reflection film on each surface of the transmission screen, for example, an amorphous fluororesin (trade name: CYTOP (C), manufactured by Asahi Glass Co., Ltd.)
ytop)) in a specific concentration of perfluorosolvent,
There is a method of applying this solution to a screen surface by spin coating, dip coating or the like so as to obtain a desired film thickness. By the way, the D line of this Cytop (wavelength 589)
The refractive index with respect to nm) is 1.34, and better performance can be obtained than with a conventional antireflection film.

In the twelfth and thirteenth embodiments, the second lenticular lens sheet 30 has the same structure as the first to third and eighth embodiments described above. The surface of the light exit surface 32 may be subjected to a treatment such as an antiglare treatment, an antistatic treatment, and a surface hardening treatment such as hard coating. When the anti-glare processing is performed, there is an effect that reflection of an object on the viewer side or illumination light on the screen screen can be reduced. Further, when the antistatic treatment is performed, there is an effect that dust can be prevented from adhering due to charging of the surface of the second lenticular lens sheet 30. Further, when the surface hardening treatment is performed, there is an effect that the surface of the second lenticular lens sheet 30 is less likely to be damaged even if an object collides from the viewer side.

In the fourth to seventh and ninth to eleventh embodiments, the light absorbing sheet 40 is provided with an anti-glare treatment on the surface of the light exit surface 42 on the image viewing side. Alternatively, a treatment such as an antistatic treatment or a surface hardening treatment such as hard coating may be performed. When these processes are performed on the light absorbing sheet 40, the same effects as those obtained by performing these processes on the second lenticular lens sheet 30 are obtained on the light absorbing sheet 40.

In each of the above embodiments, the second vertically elongated lenticular lens on the light exit surface 32 of the second lenticular lens sheet 30 has the same shape as the first vertically elongated lenticular lens on the light incident surface 31. Although the configuration is such that the lenticular lens having the aspherical shape is provided, the configuration may be such that the light emission surface 32 is simply a plane and only the light absorption band 33 is provided. In this case, the light exit surface 32
As compared with the case where the second vertically long lenticular lens is provided, the color shift of the image is slightly larger, but the other effects are equivalent.

In each of the above embodiments, adopting an aspherical horizontally long lenticular lens has the effect of reducing moiré. The details are as described in the description of the first embodiment.

Here, means for further reducing moiré generated on the screen will be described by taking the first embodiment as an example.

The moire is such that concentric circles on the Fresnel lens sheet 10, which is a component of the screen, and straight lines on the first and second lenticular lens sheets overlap each other.
It occurs as a locus connecting the intersections. This moiré is
If the straight line on the lenticular lens sheet is a vertical line, it will be horizontal from the center of the screen, if it is a horizontal line, it will be from the center of the screen to the vertical direction. It extends radially in an oblique direction.

Various ideas have been devised as a measure for reducing such moiré fringes, particularly when the concentric circles of the Fresnel lens sheet and the vertical lines of the lenticular lens sheet are conspicuous even when the light diffusing material is mixed to some extent. As a countermeasure against moire in the horizontal direction of the screen screen, Japanese Patent Application Laid-Open Nos.
No. 5, No. 5, etc. are disclosed. However, Japanese Patent Application Laid-Open No. Sho 62-112436 discloses at present only a measure against radial moiré when a horizontal line of a horizontally long lenticular lens is added to the above configuration. This application is an application showing the visual evaluation of a sample prepared on a trial basis and the rationale behind it, but it classifies and grasps the strength (conspicuousness) of several stripes generated in the oblique direction. Investigation of the principle is insufficient to find the optimal conditions, and lacks universality.

Further, as a measure for drastically avoiding the above two types of moiré, a Fresnel lens sheet or a lenticular lens sheet having a pitch given by a random number as disclosed in JP-A-59-69747 is used. Although it is considered effective to perform the method, specific types of pitches, numerical values, and the like are not given, and the actual effect is unknown because there is no specific guideline for actual manufacturing.

Therefore, here, an outline of a design method for suppressing the above-described moiré radially extending in the oblique direction in a transmission screen having a Fresnel lens sheet, a vertically long lenticular lens, and a horizontally long lenticular lens will be described first. .

Conventionally, moire has been considered as a set of trajectories of intersections of arcs and straight lines as described above. A conventional lenticular lens sheet having a vertically long lenticular lens has a black stripe of black as shown in FIG. 94, FIG. 95, and FIG.
It has been considered that a group of intersections where the black lines overlap each other appears as moiré because of having a shaded portion (non-emission area) as shown in FIG. However, in practice, the arc-shaped non-emission area of the Fresnel lens sheet is imaged by individual lenses on the lenticular lens sheet, for example, as shown in FIG. 97 to form a group of shaded points, which are geometrically shaped. Appears as a striped pattern. Whether the imaging state is imaginary or real depends on the power of the lenticular lens sheet and the positional relationship between the sheets, but due to such an optical effect, the moiré is more emphasized than the moiré simply formed by the intersections of circles and straight lines. Streaks occur. Therefore, in addition to the mutual pitch relationship between the Fresnel lens sheet and the lenticular lens sheet, which has been pointed out conventionally,
As described above, the lenticular lens sheet changes depending on the enhancement by the optical action. The present inventors evaluated the strength of such moiré by calculation and experiment from two viewpoints, a geometrical one and an optical one, and grasped the pitch relation and the arrangement relation that make the moiré difficult to see. .

In a design example described later, moire is reduced by examining the pitch relationship of each component, which is a main cause of these phenomena, and the optical action depending on the configuration and the direction of fringe generation.

The strength of the oblique moiré is determined by the density of the intersection group when the concentric circle group of the Fresnel lens and the vertical and horizontal linear groups of the lenticular lens are superimposed, and the image of each intersection formed by the vertical and horizontal lenticular lenses. Depends on the size of Each of them changes depending on the angle of intersection of a circular arc and a straight line on the Fresnel lens, and is substantially determined by the pitch relationship between the horizontally long lenticular lens and the Fresnel lens. Therefore, by setting these to a predetermined value, moire is avoided. The details will be described below.

FIG. 93 is a perspective view showing a main part of a three-screen transmission screen similar to that of the first embodiment. Figure 93
1, the Fresnel lens sheet 10 is provided with a Fresnel convex lens on the light emitting surface 12, and has a configuration in which concentric square prisms are sequentially arranged with an optical axis passing near the center of the screen as a central axis.

In the three-screen transmission screen 1, the projection light from the projection lens is incident on the light incident surface 11 of the Fresnel lens sheet 10, and the Fresnel lens sheet 1
0, the light passes through the first lenticular lens sheet 20 and the second lenticular lens sheet 30 and is diffused to the outside. In FIG. 93, the Fresnel convex lens surface of the Fresnel lens sheet 10 is arranged on the light emitting surface 12, and in this case, it is effective in suppressing uneven brightness at the peripheral portion of the screen.

FIG. 94 is a sectional view showing a section of the Fresnel lens sheet 10.

As shown in FIG. 94, the light transmitted through the Fresnel lens sheet 10 is blocked at the rising portion of the Fresnel convex lens surface and cannot pass through that portion. As a result, this rising portion becomes a non-emission region.

FIG. 95 is a plan view showing the front shape of the non-emission area of the Fresnel lens. The non-emission area forms a group of concentric shadows as shown in FIG. 95 when viewed from the front. These shade groups are the first lenticular lens sheet 20, the second lenticular lens sheet 3
When an image is formed by 0 individual lenticular lenses, and they are arranged as a group of geometrically conspicuous points, they appear as moire fringes on the viewing side.

Particularly, in the three-screen transmission screen shown in FIG. 93, large radial moire is generated in several directions from the center of the screen.

FIG. 96 is a plan view schematically showing the state of occurrence of moire in the screen screen oblique direction.

FIG. 97 is a plan view showing an example of an image of a non-emission area of a Fresnel lens sheet by a horizontally long lenticular lens.

As shown in FIG. 97, when the non-emission area of the Fresnel lens sheet forms an image with the horizontally long lenticular lens of the first lenticular lens sheet 20 as shown in FIG. There is a direction in which the shadow groups are arranged substantially in the vertical direction of the screen, and the vertically arranged shadow groups overlap with the vertically elongated lenticular lenses of the second lenticular lens sheet 30 to form radial stripes in an oblique direction. .

FIG. 98 shows a display example of moire in a screen screen oblique direction.

In the region corresponding to the first quadrant (the upper half of the right half of the screen) on the screen screen of FIG. 96, the shaded portion of the Fresnel lens is the horizontal lenticular lens and the vertical lenticular lens of the first and second lenticular lens sheets. It is an example in which a point sequence group sampled by a lens and optically enlarged is displayed. As can be seen from this example, moire extends radially in many directions from the center of the Fresnel lens.

FIG. 97 is a graph showing θ surrounded by a broken line in FIG.
The structure of the point sequence in the direction is shown in an enlarged manner. This direction θ
Is calculated from the intersection of i = 0 and j = 0 in FIG.
= I ₀ , j = j ₀ It is considered that the intersections are arranged vertically, and P _f is the pitch of the Fresnel lens, P _v is the pitch of the horizontally long lenticular lens, and i ₀ and j ₀ are arbitrary natural numbers.
Is displayed with.

[0620]

Equation 34] _{θ = Arccos (i 0 P f} / j 0 P v) The frequency of the fringes is given by the difference between the pitch P _h and P _f / sin [theta vertically long lenticular lens.

The intensity of the fringes themselves thus generated depends on the density of the individual points of the shaded portion of the Fresnel lens constituting the fringes and the size of the individual points enlarged or deformed by the vertically long lenticular lens or the horizontally long lenticular lens. depending on the Sato, each parameter depends on the ratio of the pitch P _v of the pitch P _f and landscape lenticular lens of the Fresnel lens.

FIG. 99 is a characteristic diagram showing the result of calculating the relationship between the pitch ratio P _f / P _v and the strength of moiré.

In FIG. 99, since the types (directions and intensities) of the stripes generated differ depending on the combination of i and j, various curves are drawn. Gradually increases in intensity, peaks at a certain point, and disappears after that point. In the meantime, the direction in which the stripes are generated on the screen gradually moves from a direction close to horizontal to the vertical direction, and disappears when it becomes just vertical.

As a result of sample evaluation by an experiment, when the light diffusing material is not mixed in each of the constituent elements (Fresnel lens, horizontal lenticular lens, vertical lenticular lens), the level indicated by the broken line in FIG. It turned out to be. To avoid moiré,
It is necessary to set the pitch ratio in a portion avoiding such scattered peaks, and such a region is shown in FIG.

According to FIG. 99, a single pitch in which the intensity of all moiré is equal to or less than the detection limit is a region, and the region has a portion at the end of which the skirt exceeds the detection limit. Also,
Each of the other areas has a base indicated by a bold line and exceeds the detection limit.However, a small amount of light diffusing material is added, the distance between the Fresnel convex lens and each lenticular lens is changed, and the power of each lenticular lens is changed. It is possible to make the detection limit or less due to the shielding effect such as the above-mentioned effect.

The usable pitch ratio area thus obtained is, specifically, 0 and 0.15
Between 0.33 and 0.40, between 0.5 and 0.6, between 1.0 and 1.15, between 2.0 and 2.34. Is practically non-existent, and 0.05 is the practical minimum level in consideration of light diffraction and the like.

FIG. 100, FIG. 101, and FIG. 102 are plan views showing the occurrence of moiré fringes on the screen when a single pitch is used in each of the regions.

[0628] Although various types of small stripes appear in each area, the stripes visible beyond the detection limit are i = 2, j
= 1 stripe, i = 1, j = 1 stripe, i = 1,
There are j = 2 stripes. These stripes slightly exceed the detection limit, and can be prevented from being seen by the reducing means having the shielding effect as described above.

Further, by manufacturing a Fresnel lens sheet having a plurality of types of pitches, by selecting and repeating two or more pitches from the three regions described above, a single stripe in each region is avoided. It is also possible.

FIG. 103 shows that the change in the pitch ratio (P _f / P _v ) within one cycle is 1.11⇒0.57⇒1.11⇒
The following shows the occurrence of moire when a Fresnel lens having three types of composite pitches of 0.57⇒0.35⇒0.35⇒0.57 is combined with a horizontally long and vertically long lenticular lens. Moiré is hardly noticeable, and does not require shielding by a light diffusing material or the like. In addition, there are various combinations of the above-mentioned pitch ratios in such a composite pitch, but one cycle of the span is M + 0.3 with respect to the pitch of the vertically-long lenticular lens so that they do not cause moire with the vertically-long lenticular lens. It is necessary to set so as to be in the range of ＭM + 0.7 or a reciprocal thereof. Where M is 0
Or it is a natural number.

[0631] In the above description, the description has been given based on the transmissive screen having the configuration in which the oblique moire is the strongest, in which the horizontally long lenticular lens and the vertically long lenticular lens sheet are arranged on the viewing side of the Fresnel lens sheet. The present invention is also effective for a transmission screen having a different configuration as shown in each embodiment, and is also effective for a transmission screen using a sheet into which a light diffusing material is kneaded. is there.

According to the moiré reduction design described above, in a transmissive screen in which the amount of the light diffusing material kneaded is small,
It is possible to realize a transmissive screen in which moire in an oblique direction is almost inconspicuous, and to provide a rear-projection image display device that displays a high-quality image without moire interference.

[0633] Finally, a rear projection type image display apparatus provided with the transmissive screen 1 of the first to thirteenth embodiments will be described.

In constructing the rear projection type image display device as shown in FIG. 2 using the transmission type screen 1 of each of the above embodiments, the following conventional contrast improving measures are used together. Is preferred.

That is, in the coupler 9G that couples the projection type cathode ray tube 7G and the projection lens 8G shown in FIG. 2, the lens element arranged closest to the projection type cathode ray tube 7G among the lens groups constituting the projection lens 8G The projection-type CRT 7G has a concave surface with a convex surface and the transmission-type screen has a concave surface, and a liquid refrigerant is sealed in a space formed between the concave lens and the projection-type CRT 7G.

FIG. 104 is a cross-sectional view showing a cross section of a joint between the projection type cathode ray tube and the projection lens in the rear projection type image display device of FIG.

In FIG. 104, 7G is a green projection type CRT, 8G is a projection lens for the projection type CRT 7G,
9G is a coupler for connecting the projection type cathode ray tube 7G and the projection lens 8G, 81, 82, 83, and 84 are first, second, third, and fourth lens elements of the projection lens 8G, respectively, and 85 is a lens barrel. is there.

The first lens element 81 is a concave lens having a convex surface on the projection type cathode ray tube 7G side and a concave surface on the transmission type screen side. The liquid coolant 91 is provided in the space between the lens element 81 and the projection type cathode ray tube 7G. Is enclosed. The portion of the projection type cathode ray tube 7G which is in contact with the liquid refrigerant 91 is usually made of glass, the lens element 81 is made of glass or plastic, and the liquid refrigerant 91 is ethylene glycol, water, glycerin, or a mixture thereof.

At this time, when there is no liquid refrigerant 91 and there is merely air between the projection type cathode ray tube 7G and the lens element 81, one of the image light emitted from the projection type cathode ray tube 7G and reaching the lens element 81 is removed. Is reflected by the reflection loss of light at the interface between the projection-type cathode ray tube 7G and the liquid refrigerant 91 and at the interface between the liquid refrigerant 91 and the lens element 81.
If the stray light travels through the projection optical system of the rear projection type image display apparatus or the inside of the housing and reaches the transmissive screen after the stray light has passed through the projection optical system, a high image contrast cannot be obtained.

On the other hand, when there is a liquid refrigerant 91,
Projection type cathode ray tube 7G, liquid refrigerant 91, lens element 81
Are both close to 1.5, the image light emitted from the projection cathode-ray tube 7G and reaching the lens element 81 passes through the boundary between the projection cathode-ray tube 7G and the liquid refrigerant 91 and the liquid refrigerant 91. The reflection loss of light at the interface between the lens and the lens element 81 is extremely small, and a good image contrast is obtained.

In the above description, the combination of the green CRT and the projection lens has been described. The same applies to the combination of the red and blue CRT and the projection lens.

Therefore, by using the above-described contrast improvement measure of sealing the liquid refrigerant in the space between the concave lens and the projection type cathode-ray tube 7G together with the transmissive screen of each of the above embodiments, the image contrast can be further improved. A better rear projection type image display device is obtained.

In FIG. 104, the projection lens 8
G is composed of four lens elements. Such a projection lens is disclosed in, for example, Japanese Patent Application Laid-Open No. 1-2509.
The projection lens disclosed in Japanese Patent Application Publication No. 16 can be applied. However, the configuration of the projection lens is not limited to this.
No. 2, JP-A-3-276113, U.S. Pat.
A projection lens disclosed in Japanese Patent Application No. 963007 can also be applied.

Also, when the rear projection type image display device as shown in FIG. 2 is constructed by using the transmissive screen 1 of each of the above embodiments, the following conventional focus characteristics of the image are obtained. It is preferable to use improvement measures together.

That is, as the reflecting mirror 110 shown in FIG. 2, the projection lens 8G of the surface of the base material of the reflecting mirror 110 is used.
In addition, a light-reflective optical thin film is formed on the surface on the side facing the transmission screen 1. Alternatively, of the surface of the base 110B of the reflecting mirror 110, an antireflection film is provided on the surface facing the projection lens 8G and the transmissive screen 1, and on the surface of the base 110B opposite to this surface. The light reflecting optical thin film 111 is formed as a film.

FIG. 105 is an enlarged sectional view of the reflecting mirror 110 in the rear projection type image display device of FIG.

[0647] In Fig. 105, 110B is the reflecting mirror 11
0, which is usually made of a glass plate. Also, 10
0 'is an incident light beam, and 111 is a light reflective optical thin film.

In FIG. 105, (a) shows a light-reflective optical thin film 111 formed on the surface of the base 110B of the reflecting mirror 110 on the side facing the projection lens 8G and the transmissive screen 1. (B) shows a light reflecting optical thin film 111 on the surface of the base 110B of the reflecting mirror 110 opposite to the surface facing the projection lens 8G and the transmissive screen 1. Each of the reflecting mirrors having a film-formed configuration is shown.

In the reflecting mirror 110 shown in FIG. 105 (b), the incident light beam 100 'is applied to the base 110B of the reflecting mirror 110.
As a result, the reflected light spreads, and as a result, a good image focus characteristic on the transmission screen 1 cannot be obtained.

On the other hand, in the reflecting mirror 110 shown in FIG. 105 (a), the incident light beam 100 'is reflected by the surface of the reflecting mirror 110 facing the projection lens 8G and the transmission screen 1, so that the reflected light is reflected. Does not spread, and a good image focus characteristic can be obtained on the transmission screen 1.

Also, the reflecting mirror 110 shown in FIG.
In the above, by providing an antireflection film on the surface of the reflecting mirror 110 on the side facing the projection lens 8G and the transmissive screen 1, the multiple reflection of the incident light beam 100 'in the base 110B of the reflecting mirror 110 is greatly reduced. Because of the decrease, the reflected light does not spread, and good image focus characteristics can be obtained on the transmissive screen 1.

Therefore, as the reflecting mirror 110, the light reflecting optical thin film 111 is formed on the surface of the base 110B of the reflecting mirror 110 which faces the projection lens 8G and the transmission screen 1. Or
An anti-reflection film is provided on the surface of the base 110B of the reflecting mirror 110 facing the projection lens 8G and the transmissive screen 1, and the base 11 on the side opposite to this surface is provided.
The image focus characteristic is improved by using the above-described measure for improving the image focus characteristic in which the light-reflective optical thin film 111 is formed on the surface of the OB in combination with the transmission screen of each of the above embodiments. , A rear projection type image display device having a better image quality can be obtained.

The above description has been made with respect to an optical system using three red, green, and blue monochromatic projection type cathode-ray tubes and an image display device using the optical system. Use an optical system that projects a color image such as a slide film (including a case where the image is synthesized in the middle of the optical system) with a single projection lens, or the optical system when the number of images is increased to books, etc. It goes without saying that the case of the image display device described above is also substantially included in the present invention.

[0654]

As is apparent from the above description, according to the present invention, the projected image light from an image source such as a projection type cathode-ray tube enters a transmission type screen via a projection lens, and is projected on the screen screen horizontally. In the direction is diffused by the aspherical vertically long lenticular lens of the light entrance surface and the light exit surface of the second lenticular lens sheet, and in the screen screen vertical direction mainly the Fresnel lens sheet, or the first lenticular lens sheet, or The light is diffused by an aspherical horizontally long lenticular lens provided on the light incident surface or light exit surface of the light absorbing sheet.

[0655] Therefore, according to the present invention, the drastic improvement of the directional characteristics in the horizontal direction of the screen screen and the drastic reduction of the color shift can be realized by optimizing the aspherical shape of the vertically long lenticular lens.

By optimizing the aspherical shape of the above-mentioned horizontally long lenticular lens, the directional characteristics in the vertical direction of the screen screen can be widened and the vertical viewing angle can be increased.

In the case of using the microlens sheet 50 in which the microlens elements are continuously arranged in the horizontal and vertical directions on the screen, the shape of the horizontal section and the vertical section of the screen should be optimized. Thereby, the same directional characteristics as described above can be realized.

Also, a convex lenticular lens having a convex shape on the image generating source side and a concave lenticular lens having a concave shape on the image generating source side are used as the above-mentioned horizontally long lenticular lens, and both of them are alternately continuous. When using a plurality of horizontally oriented lenticular lenses, the lens surfaces may intersect at a sharp intersection angle as the shape of the boundary between adjacent lenticular lenses even if the radius of curvature of these horizontally elongated lenticular lenses is reduced. Therefore, when an attempt is made to mold using a molding die, the shape of the boundary between the horizontally long lenticular lenses can be reproduced almost completely, and the screen has good moldability.

In the case where a horizontally long lenticular lens having a vertically asymmetric cross-sectional shape is used as the above horizontally long lenticular lens, a vertically asymmetric directional characteristic suitable for a rear projection type image display device is obtained as a directional characteristic in a screen screen vertical direction. There is an effect that a rear-projection image display device in which the entire screen is bright even when viewed from various viewing positions can be obtained.

Also, in the present invention, the directional characteristics in the vertical direction of the screen can be sufficiently widened by the horizontal lenticular lens of the Fresnel lens sheet, the first lenticular lens sheet, or the light absorbing sheet. The lens sheet, the second lenticular lens sheet, or the light absorbing sheet may contain no light diffusing material at all, or may contain a small amount of light diffusing material. Therefore, the image is less likely to be blurred by the light diffusing material, and good focus characteristics can be obtained. In addition, since the incident light is less scattered by the light diffusing material to generate stray light, and external light such as illumination light is also less scattered by the light diffusing material, the image is reduced compared to the conventional transmission screen. Brightness,
This has the effect of improving the contrast.

Further, in the present invention, the translucent colored light absorbing sheet is arranged on the image viewing side, or the second lenticular lens sheet is translucently colored. When there is external light, there is an effect that the ratio of the loss light is larger in the external light than in the projected image light, and the contrast is further improved.

In the present invention, among the Fresnel lens sheet, the first lenticular lens sheet and the second lenticular lens sheet, the thickness of the first lenticular lens sheet is minimized. Since the horizontal lenticular lens and the vertical lenticular lens on the light incident surface of the second lenticular lens sheet are arranged close to each other, the starting point of light diffusion of the incident light flux in the horizontal direction on the screen screen And the start point of the light diffusion in the vertical direction of the screen screen are close to each other, so that there is an effect that a good image focus characteristic can be obtained even if the directivity in the vertical direction of the screen screen is enlarged.

Further, a Fresnel lens sheet on the light emitting surface of the Fresnel lens sheet is formed by disposing a light absorbing sheet having a large sheet thickness to make the Fresnel lens sheet thinner than the Fresnel lens sheet in the conventional transmission screen. Ghosts due to unnecessary reflection of the projected image light can be made inconspicuous, and good image focus characteristics can be obtained even when a horizontally long lenticular lens is provided on the light incident surface of the Fresnel lens sheet.

Also, when an anti-glare treatment is performed as a surface treatment of the light emitting surface of the light absorbing sheet or the second lenticular lens sheet, an object on the image viewing side or illumination light is reflected on the screen screen. There is an effect that can be prevented. Further, when the antistatic treatment is similarly performed, there is an effect that dust can be prevented from adhering due to charging of the surface of the light absorbing sheet or the second lenticular lens sheet. Furthermore, when a surface hardening treatment such as a hard coating treatment is performed, even if any object collides from the image viewing side, there is an effect that the surface of the light absorbing sheet or the second lenticular lens sheet is hardly damaged. .

[Brief description of the drawings]

FIG. 1 is a perspective view showing a main part of a transmission screen as a first embodiment of the present invention.

FIG. 2 is a sectional view showing a main part of a rear projection type image display device using the transmission type screen of FIG.

FIG. 3 is a schematic development view when the projection optical system of the rear projection type image display device of FIG. 2 is developed on a horizontal plane.

FIG. 4 is a sectional view showing a vertical section of the transmission screen of FIG. 1;

FIG. 5 is a cross-sectional view showing a vertical cross section of a first lenticular lens sheet of the transmission screen of FIG. 1;

FIG. 6 is a diagram showing a coordinate system for defining an aspherical shape of each lenticular lens of the transmission screen.

FIG. 7 is an explanatory diagram for explaining a diffusion function of a vertically long lenticular lens of the transmission screen of FIG. 1;

FIG. 8 is an explanatory diagram for explaining a diffusion function of a vertically long lenticular lens of a general transmission screen.

FIG. 9 is an explanatory diagram for explaining a diffusion function of a vertically long lenticular lens of the transmission screen of FIG. 1;

FIG. 10 is a second lenticular lens sheet 3 in Table 1.
FIG. 9 is a characteristic diagram showing a directivity characteristic in a horizontal direction of a screen screen according to a design example of No. 0;

FIG. 11 is a second lenticular lens sheet 3 shown in Table 1.
FIG. 10 is a characteristic diagram illustrating directivity characteristics of a screen image in a horizontal direction for red and blue video light according to a design example of No. 0.

FIG. 12 is a characteristic diagram showing a change in the lens action relating to the shape of the first vertically long lenticular lens, comparing the transmission screen of the present invention with the transmission screen of the prior art.

FIG. 13 is a characteristic diagram showing a change in the lens action relating to the shape of the second vertically long lenticular lens by comparing the transmission screen of the present invention with the transmission screen of the prior art.

FIG. 14 is a second lenticular lens sheet 3 in Table 2.
FIG. 9 is a characteristic diagram showing a directivity characteristic in a horizontal direction of a screen screen according to a design example of No. 0;

FIG. 15 is a second lenticular lens sheet 3 in Table 2.
FIG. 10 is a characteristic diagram illustrating directivity characteristics of a screen image in a horizontal direction for red and blue video light according to a design example of No. 0.

FIG. 16: Second lenticular lens sheet 3 in Table 3
FIG. 10 is a ray tracing diagram showing how a ray travels when green image light is incident according to a design example 0.

FIG. 17 is a second lenticular lens sheet 3 in Table 3.
FIG. 10 is a characteristic diagram showing directivity characteristics of red, green, and blue video light in a horizontal direction of a screen screen according to a design example of 0.

FIG. 18 is a second lenticular lens sheet 3 in Table 3.
FIG. 9 is a characteristic diagram showing directivity characteristics of a red, green, and blue image light in a horizontal direction of a screen screen, based on a prototype screen based on a design example of No. 0.

FIG. 19 is a second lenticular lens sheet 3 in Table 3.
It is sectional drawing which shows the measured shape of the cross-sectional shape of the 1st vertically long lenticular lens of the prototype screen based on the design example of No. 0 compared with a design shape.

FIG. 20: Second lenticular lens sheet 3 in Table 3
FIG. 11 is a characteristic diagram showing the magnitude of distortion of the sag amount with respect to the design shape of the actually measured cross-sectional shape of the first vertically long lenticular lens of the prototype screen based on the design example of No. 0.

FIG. 21 is a characteristic diagram showing a second-order differential value of a cross-sectional shape of a first vertically elongated lenticular lens in comparison with an elliptical case and a parabolic case in a conventional transmission screen.

FIG. 22 compares the second derivative of the cross-sectional shape of the first vertically elongated lenticular lens in the case of the design example of the second lenticular lens sheet 30 in Table 4 and the case of the ellipse in the transmission screen of the prior art. FIG.

FIG. 23: Second lenticular lens sheet 3 in Table 4
FIG. 10 is a characteristic diagram showing directivity characteristics of red, green, and blue video light in a horizontal direction of a screen screen according to a design example of 0.

FIG. 24: Second lenticular lens sheet 3 in Table 4
In the case where the distortion shown in FIG.
FIG. 4 is a characteristic diagram showing directivity characteristics of red, green, and blue video light in a horizontal direction of a screen screen.

FIG. 25 compares the second derivative of the cross-sectional shape of the first vertically elongated lenticular lens in the case of the design example of the second lenticular lens sheet 30 in Table 5 and in the case of an ellipse in a conventional transmission screen. FIG.

FIG. 26: Second lenticular lens sheet 3 in Table 5
FIG. 10 is a characteristic diagram showing directivity characteristics of red, green, and blue video light in a horizontal direction of a screen screen according to a design example of 0.

FIG. 27: Second lenticular lens sheet 3 in Table 5
In the case where the distortion shown in FIG.
FIG. 4 is a characteristic diagram showing directivity characteristics of red, green, and blue video light in a horizontal direction of a screen screen.

FIG. 28 is an explanatory diagram for explaining a diffusion function of the horizontally long lenticular lens of the transmission screen of FIG. 1;

29 is a cross-sectional view schematically showing the shape of a design example of a horizontally long lenticular lens in Table 6 and diffusion of light in a vertical direction of a screen screen. FIG.

FIG. 30 is a diagram illustrating directivity characteristics in a vertical direction of a screen screen according to a design example of the horizontally long lenticular lens in Table 6.

FIG. 31 is a characteristic diagram showing a comparison between a transmission screen according to the present invention and a transmission screen according to the related art with respect to a change in lens action relating to the shape of a horizontally long lenticular lens.

FIG. 32 is a perspective view showing a main part of a transmission screen as a modification of the first embodiment of the present invention.

FIG. 33 is a perspective view showing a main part of a transmission screen as a modification of the first embodiment of the present invention.

FIG. 34 is a perspective view showing a main part of a transmission screen as a modification of the first embodiment of the present invention.

FIG. 35 is a perspective view showing a main part of a transmission screen as a modification of the first embodiment of the present invention.

FIG. 36 is a sectional view showing a vertical section of the transmission screen of FIG. 35;

FIG. 37 is a cross-sectional view showing vertical cross sections of a Fresnel lens sheet in a conventional transmission screen, a first lenticular lens sheet in the transmission screen of FIG. 1, and a first lenticular lens sheet in the transmission screen of FIG. is there.

FIG. 38 is a characteristic diagram schematically showing the directivity of the transmissive screen 1 in the vertical direction of the screen when the horizontally long lenticular lens shown in FIG. 37 is used.

39 is a cross-sectional view showing a shape of a design example of the horizontally long lenticular lens shown in Table 7. FIG.

40 is a cross-sectional view schematically showing diffusion of light in the vertical direction of the screen screen according to the design example of the horizontally long lenticular lens shown in Table 7. FIG.

41 is a characteristic diagram illustrating directivity characteristics in a vertical direction of a screen screen according to a design example of the horizontally long lenticular lens in Table 9. FIG.

42 is a characteristic diagram showing directivity characteristics in a vertical direction of a screen screen according to a design example of a horizontally long lenticular lens in Table 10. FIG.

FIG. 43 is a characteristic diagram showing directivity characteristics in a vertical direction of a screen screen according to a design example of a horizontally long lenticular lens shown in Table 11.

44 is a cross-sectional view showing the shape of a design example of the horizontally long lenticular lens shown in Table 12. FIG.

FIG. 45 is a cross-sectional view schematically showing light diffusion in the vertical direction of a screen screen according to a design example of the horizontally long lenticular lens shown in Table 12.

FIG. 46 is a cross-sectional view showing the shape of a design example of the horizontally long lenticular lens in Table 13.

FIG. 47 is a cross-sectional view schematically showing diffusion of light in the vertical direction of a screen screen according to a design example of the horizontally long lenticular lens shown in Table 13.

FIG. 48 is a cross-sectional view showing the shape of a design example of the horizontally long lenticular lens in Table 15.

FIG. 49 is a characteristic diagram showing directivity characteristics in a vertical direction of a screen screen according to a design example of the horizontally long lenticular lens in Table 15.

50 is a cross-sectional view showing a shape of a design example of the horizontally long lenticular lens shown in Table 16. FIG.

FIG. 51 is a characteristic diagram showing directivity characteristics in a vertical direction of a screen screen according to a design example of the horizontally long lenticular lens in Table 16.

FIG. 52 is a cross-sectional view showing ray tracing in a vertical cross-sectional shape of a horizontally long lenticular lens having a vertically asymmetric shape.

FIG. 53 is an enlarged sectional view showing a sectional shape of the horizontally long lenticular lens of FIG. 52;

FIG. 54 is a characteristic diagram showing a directivity characteristic in a vertical direction of a screen screen which is a target in designing a horizontally long lenticular lens having a vertically asymmetric shape.

FIG. 55 is a cross-sectional view showing a vertical cross-sectional shape of the horizontally long lenticular lens designed based on the directivity of the screen screen in the vertical direction of FIG. 54.

FIG. 56 is a characteristic diagram showing a directivity characteristic in a vertical direction of a screen screen which is a target in designing a horizontally long lenticular lens having a vertically asymmetric shape.

FIG. 57 is a cross-sectional view showing a vertical cross-sectional shape of the horizontally long lenticular lens designed based on the directivity of the screen screen in the vertical direction of FIG. 56.

FIG. 58 is a cross-sectional view showing a vertical cross-sectional shape of a modification of the horizontally long lenticular lens designed based on the directivity of the screen screen in the vertical direction in FIG. 56.

59 is a sectional view showing a propagation path of illumination light in a vertical section of the horizontally long lenticular lens of FIG. 57.

60 is a cross-sectional view showing a propagation path of illumination light in a vertical cross section of the horizontally long lenticular lens of FIG. 58.

FIG. 61 is a cross-sectional view showing the spread of light in the vertical direction of the screen screen in the transmission screen of the two-stage multi-screen rear-projection image display device.

FIG. 62 is a perspective view showing a main part of a transmission screen as a second embodiment of the present invention.

FIG. 63 is a perspective view showing a main part of a transmission screen as a third embodiment of the present invention.

FIG. 64 is a perspective view showing a main part of a transmission screen as a fourth embodiment of the present invention.

FIG. 65: Base material 40 in light absorbing sheet 40 of FIG. 64
Color tone N0 of acrylic filter NG as a specific example of B
It is a characteristic view which shows the characteristic of the transmittance | permeability with respect to the light beam of each wavelength of 99.

FIG. 66: Base material 40 in the light absorbing sheet 40 of FIG. 64
Color tone N0 of acrylic filter NG as a specific example of B
It is a characteristic view which shows the characteristic of the transmittance | permeability with respect to the light beam of each wavelength of 97.

FIG. 67 is a perspective view showing a main part of a transmission screen as a fifth embodiment of the present invention.

FIG. 68 is a perspective view showing a main part of a transmission screen as a sixth embodiment of the present invention.

FIG. 69 is a perspective view showing a main part of a transmission screen as a seventh embodiment of the present invention.

70 is a cross-sectional view showing a vertical cross section of a Fresnel lens sheet in the conventional transmission screen and the transmission screen of FIG.

FIG. 71 is a perspective view showing a main part of a transmission screen as an eighth embodiment of the present invention.

FIG. 72 is a perspective view showing a main part of a transmission screen as a modification of the eighth embodiment of the present invention.

FIG. 73 is a perspective view showing a main part of a transmission screen as a modification of the eighth embodiment of the present invention.

74 is a diagram showing directivity characteristics in a screen screen vertical direction when the design example of the horizontally long lenticular lens shown in Table 6 is applied to the transmission screen of FIG. 73.

FIG. 75 is a perspective view showing a main part of a transmission screen as a modification of the eighth embodiment of the present invention.

76 is a sectional view showing a vertical section of the transmission screen of FIG. 75.

FIG. 77 is a cross-sectional view showing a vertical cross section of a Fresnel lens sheet in a conventional transmission screen and the transmission screen of FIG.

FIG. 78 is a cross-sectional view showing another specific example of the Fresnel lens sheet in the transmission screen of FIG. 75.

FIG. 79 is a perspective view showing a main part of a transmission screen as a ninth embodiment of the present invention.

FIG. 80 is a perspective view showing a main part of a transmissive screen as a tenth embodiment of the present invention.

FIG. 81 is a perspective view showing a main part of a transmission screen as a modified example of the tenth embodiment of the present invention.

FIG. 82 is a perspective view showing a main part of a transmissive screen as an eleventh embodiment of the present invention.

FIG. 83 is an explanatory diagram for explaining a diffusion function of the horizontally long lenticular lens of the transmission screen of FIG. 82;

FIG. 84 is a characteristic diagram showing directivity characteristics in a vertical direction of a screen screen according to a design example of a horizontally long lenticular lens in Table 19.

FIG. 85 is a perspective view showing a main part of a transmissive screen as a modification of the eleventh embodiment of the present invention.

86 is a sectional view showing a vertical section of the transmission screen of FIG. 85.

FIG. 87 is a diagram showing directivity characteristics in the vertical direction of the screen screen when the design example of the horizontally long lenticular lens shown in Table 19 is applied to a transmissive screen as a modification of the eleventh embodiment of the present invention.

FIG. 88 is a perspective view showing a main part of a transmission screen as a twelfth embodiment of the present invention.

FIG. 89 is a perspective view showing a main part of a transmissive screen as a modification of the eleventh embodiment of the present invention.

FIG. 90 is a perspective view showing a main part of a transmission screen as a thirteenth embodiment of the present invention.

FIG. 91 is a perspective view showing a main part of a transmission screen as an application example of the eighth embodiment of the present invention.

FIG. 92 is a perspective view showing a main part of a transmission screen as an application example of the eighth embodiment of the present invention.

FIG. 93 is a perspective view showing a main part of a transmission screen as the first embodiment of the present invention.

FIG. 94 is a sectional view showing a non-emission area of the Fresnel lens.

FIG. 95 is a plan view showing the front shape of the non-emission area of the Fresnel lens.

FIG. 96 is a plan view schematically showing the state of occurrence of moire in an oblique direction.

FIG. 97 is a plan view showing an example of an image of a screen shading portion by a horizontal lenticular lens.

FIG. 98 is a plan view in which the state of occurrence of moire in an oblique direction is calculated and displayed.

FIG. 99 is a characteristic diagram showing a relationship between a moire intensity in an oblique direction and a pitch ratio.

FIG. 100 is an example of calculation display of a state of occurrence of oblique moiré.

FIG. 101 is a calculation display example of the state of occurrence of oblique moiré.

FIG. 102 is a calculation display example of the state of occurrence of oblique moiré.

FIG. 103 is a calculation display example of the state of occurrence of oblique moiré.

104 is a cross-sectional view showing a cross section of a joint between the projection type cathode ray tube and the projection lens in the rear projection type image display device of FIG. 2;

FIG. 105 is a cross-sectional view showing a cross section of a reflecting mirror in the rear projection type image display device of FIG. 2;

FIG. 106 is a perspective view showing a main part of a transmission screen according to the related art.

FIG. 107 is a perspective view showing a main part of a transmission screen according to the related art.

FIG. 108 is a cross-sectional view showing a vertical cross section of a Fresnel lens sheet of a transmission screen according to the related art.

FIG. 109 is a cross-sectional view showing a horizontal cross section of a lenticular lens sheet of a transmission screen according to the related art.

FIG. 110 is a cross-sectional view showing a horizontal cross section of a lenticular lens sheet of a transmission screen according to the related art.

FIG. 111 is a cross-sectional view showing a vertical section and a horizontal section of a lenticular lens sheet of a transmission screen according to the related art.

FIG. 112 is an explanatory diagram for describing a general horizontal viewing angle α and a vertical viewing angle β.

FIG. 113 is a characteristic diagram showing a directional characteristic in a horizontal direction and a directional characteristic in a vertical direction of a screen obtained in a transmission screen according to the related art.

FIG. 114 is a characteristic diagram showing directivity characteristics of a horizontally long lenticular lens alone of a Fresnel lens sheet of a transmission screen according to the related art in a vertical direction of a screen screen.

FIG. 115 is a characteristic diagram showing another example of the directivity in the vertical direction of the screen obtained in the transmission screen according to the related art.

FIG. 116 is a characteristic diagram showing horizontal directional characteristics and vertical directional characteristics of an ideal screen screen to be obtained in a transmissive screen.

FIG. 117 is a sectional view showing a vertical section of the transmission screen of FIG. 1;

FIG. 118 is a sectional view showing a horizontal section of the transmission screen of FIG. 1;

FIG. 119 is a characteristic diagram showing directional characteristics in the horizontal direction of the screen screen for red, green, and blue image light obtained in a transmission screen according to the related art.

FIG. 120 is a characteristic diagram showing another example of the directional characteristics in the horizontal direction of the screen screen with respect to red and blue image light obtained in a transmission screen according to the related art.

FIG. 121 is a characteristic diagram showing a comparison between the luminance distribution in the vertical direction of the screen of the transmissive screen of FIG. 1 and the luminance distribution in the vertical direction of the screen of the transmissive screen of FIG. 107;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Transmission screen, 1A ... Upper transmission screen, 1B ... Lower transmission screen, 6 ... Light diffusing material, 7
R, 7G, 7B ... projection type cathode ray tube, 8R, 8G, 8B
... Projection lens, 9G ... coupler, 10 ... Fresnel lens sheet, 10B ... base material of Fresnel lens sheet, 11 ... light incident surface of Fresnel lens sheet, 12 ... light emission surface of Fresnel lens sheet, 20 ... first lenticular Lens sheet, 20B: Base material of first lenticular lens sheet, 21: Light incident surface of first lenticular lens sheet, 22: Light emitting surface of first lenticular lens sheet, 23: Horizontal plane, 24: Flat part, Reference numeral 30 denotes a second lenticular lens sheet, 30B denotes a base of the second lenticular lens sheet, 30 'denotes a lenticular lens sheet, 30B' denotes a base of the lenticular lens sheet, and 31 denotes a light incident surface of the second lenticular lens sheet. , 31 ': the light incident surface of the lenticular lens sheet,
32 ... the light emitting surface of the second lenticular lens sheet,
32 ': light emitting surface of the lenticular lens sheet, 32
P: convex protrusion of the second lenticular lens sheet;
33: light absorption band, 40: light absorption sheet, 40B: base material of light absorption sheet, 41: light incident surface of light absorption sheet, 41 ...
Light emitting surface of light absorbing sheet, 50: micro lens sheet, 50B: base material of micro lens sheet, 51: light incident surface of micro lens sheet, 52: light emitting surface of micro lens sheet, 81: first lens element 82, a second lens element, 83, a third lens element, 84, a fourth lens element, 85, a lens barrel, 91, a liquid refrigerant, 11
0: Reflecting mirror, 110B: Substrate of reflecting mirror, 111: Light-reflective optical thin film, 120: Housing.

Continued on the front page (31) Priority claim number Japanese Patent Application No. 4-203449 (32) Priority date July 30, 1992 (1992.7.30) (33) Priority claim country Japan (JP) (31) Priority claim number Japanese Patent Application No. Hei 5-92736 (32) Priority date April 20, 1993 (1993. 4.20) (33) Priority claim country Japan (JP) (31) Priority claim number 5-84417 (32) Priority date April 12, 1993 (April 12, 1993) (33) Priority country Japan (JP) (72) Inventor Atsuo Osawa 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa-ken Inside Hitachi, Ltd.Video Media Research Lab. No. 292, Hitachi, Ltd. Image Media Research Laboratory, Hitachi, Ltd. (56) References JP-A-60-263932 (JP, A) JP-A-2-72341 (JP, A) JP-A-3-39944 (JP, A) JP Hei 3 220542 (JP, A) JP Akira 62-121436 (JP, A) (58 ) investigated the field (Int.Cl. ^7, DB name) G03B 21/62 G03B 21/10

Claims (8)

(57) [Claims] An at least one Fresnel lens surface ;
Vertical lenticular lens that extends perpendicular to the surface
An elongated lenticular lens surface having a plurality arranged in direction, image
Horizontal lenticular lens extending in the horizontal direction
A transmission type screen of a projection type image display device having a plurality of horizontally oriented lenticular lens surfaces arranged in two directions , wherein each of the plurality of horizontally elongated lenticular lenses is
The surface is more perpendicular to the lens optical axis than near the optical axis.
An aspherical shape where the distant part has a stronger refractive power
No, and a pitch ratio P _f / P _v between the pitch P _v of the horizontal lenticular lens pitch P _f of the Fresnel lens,
0.05-0.15, 0.33-0.40, 0.5-
A transmission screen, wherein the transmission screen is set to at least one of 0.6, 1.0 to 1.15, and 2.0 to 2.34. 2. The transmission screen according to claim 1, wherein a vertical lenticular lens surface and a horizontal lenticular lens surface are arranged on the image viewing side of the Fresnel lens surface. 3. The transmission type screen according to claim 1, wherein a vertical lenticular lens surface is disposed on an image viewing side of the Fresnel lens surface, and a horizontal lenticular lens surface is disposed on an image generation source side. screen. 4. A pitch P of the vertically elongated lenticular lens.
compared to _h, the transmissive screen of claim 1, the pitch P _v of the pitch P _f and landscape lenticular lens of the Fresnel lens and wherein the go both small. 5. An image forming apparatus comprising: at least one Fresnel lens surface;
Vertical lenticular lens that extends perpendicular to the surface
An elongated lenticular lens surface having a plurality arranged in direction, image
Horizontal lenticular lens extending in the horizontal direction
And a plurality arrayed horizontally lenticular lens surface direction, the vertical than the pitch P _h of the lenticular lens, are small projection type image display pitch P _v of the horizontal lenticular lens pitch P _f of the Fresnel lens In the transmission screen of the device , each of the plurality of horizontally long lenticular lenses
The surface is more perpendicular to the lens optical axis than near the optical axis.
An aspherical shape where the distant part has a stronger refractive power
No, the pitch ratio P _f / P _v between the pitch P _v of the pitch P _f of the Fresnel lens the Horizontal Renchikyu <br/> Rarenzu, 0.
05-0.15, 0.33-0.40, 0.5-0.
6. A transmissive screen characterized by having a composite pitch having at least two of the following: 6, 1.0 to 1.15, and 2.0 to 2.34. 6. An image forming apparatus comprising: at least one Fresnel lens surface;
Vertical lenticular lens that extends perpendicular to the surface
An elongated lenticular lens surface having a plurality arranged in direction, image
Horizontal lenticular lens extending in the horizontal direction
And a plurality arrayed horizontally lenticular lens surface direction, the vertical than the pitch P _h of the lenticular lens, are small projection type image display pitch P _v of the horizontal lenticular lens pitch P _f of the Fresnel lens In the transmission screen of the device , each of the plurality of horizontally long lenticular lenses
The surface is more perpendicular to the lens optical axis than near the optical axis.
An aspherical shape where the distant part has a stronger refractive power
No, the pitch ratio P _f / P _v between the pitch P _v of the pitch P _f of the Fresnel lens the Horizontal Renchikyu <br/> Rarenzu, 0.
05-0.15, 0.33-0.40, 0.5-0.
A composite pitch having at least two of the 6,1.0～1.15,2.0～2.34, the sum P of the pitches of the one period, the pitch P _h of the vertical lenticular lens A transmission screen, wherein P / P _h = M + 0.3 to M + 0.7 (M; natural number) or a reciprocal thereof. 7. The optical system according to claim 1, wherein a focal length of a portion far from the optical axis is shorter than a focal length near the optical axis of each of the horizontally long lenticular lenses.
A transmission screen according to any one of the above. 8. A transmission type screen used in a projection type image display device, wherein a Fresnel lens sheet on which a Fresnel lens is formed, and a first lenticular lens extending in a horizontal direction of the screen are provided on a light incident surface thereof in a vertical direction. A transmission screen having a plurality of arranged first lenticular lens sheets and a second lenticular lens sheet in which a plurality of second lenticular lenses extending in a surface screen vertical direction are arranged in a horizontal direction on a light incident surface thereof. The first lenticular lens has an aspherical shape such that a portion vertically separated from the optical axis of the lens surface has a stronger refractive power than a portion near the optical axis of the lens. The focal length of a portion far from the optical axis is shorter than the focal length near the optical axis of the first lenticular lens. And a transmission screen.