JPH11174403A - Illuminator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently irradiate a surface such as a liquid crystal panel with light by providing an illuminator with a light converting means for converting light from a lamp into a parallel beam and allowing its irradiated area to correspond to the diagonal size of the surface. SOLUTION: A light emitting part 3 is arranged in a reflector 2 constituted of a paraboloidal face in a lamp 1, light from the light emitting part 3 is reflected on the inner surface of the reflector 2 and exits from an aperture part with a diameter ϕa to the front as a parallel beam. A condenser lens 4 is arranged as a converging convex lens in the front of the lamp 1 to converge light from the reflector 2 upon the incident plane of a concave plane lens 5. The lens 5 coverts the light from the lens 4 into a parallel beam capable of irradiating the area of a diameter ϕb and projects the parallel light. The diameter ϕb of the parallel beam projected from the lens 5 is made the length corresponding to the diagonal of a surface such as a liquid crystal panel. Consequently light capable of irradiating an efficient irradiation area on the surface can be formed by the lens 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting device used as a light source of a liquid crystal projector, for example.

[0002]

2. Description of the Related Art FIG. 11 is a schematic diagram showing an example of a configuration of an optical system of a single-panel type liquid crystal projector using one liquid crystal panel, for example. The lamp 40 has, for example, an elliptical reflector 40a, and reflects the light emitted from the light emitting unit 40b forward. Although not shown, it is also known to use a lamp having a parabolic reflector, for example, and to arrange a light collecting means such as a condenser lens in front of the lamp to collect light. Light emitted from the lamp 40 (RG
B) is a field lens 4 via a relay lens system 41.
2 is incident. Although not shown, the relay lens system 41 is provided with a condensing grating, and an image passing through the grating is used as a virtual light source and enters the field lens 42.

The field lens 42 is a relay lens system 4
1 can be emitted as parallel light, that is, the relay lens 41 and the field lens 42 form a telecentric system. The light beam emitted as parallel light from the field lens 42 is separated into RGB colors by a color separation unit 43. The color separation unit 43 includes a dichroic mirror 43R that reflects only red light, a dichroic mirror 43G that reflects only green light, and a dichroic mirror 43B that reflects only blue light. For example, they are arranged at an angle of about 45 °. Each dichroic mirror 43 (R, G, B) is arranged with a predetermined tilt angle δ so as to diverge and emit in the same direction as a horizontal line of an image formed by a liquid crystal panel described later. Each color light reflected here is emitted at an angle of divergence of 2δ to perform color separation.

[0004] Each color light (R, R,
G, B) are, for example, about 4
The light is reflected by a total reflection mirror 44 arranged at an angle of 5 ° and is incident on a liquid crystal panel section 48 including, for example, a polarizing plate 45, a liquid crystal panel 46, a polarizing plate 47, and the like. The liquid crystal panel 46 drives a liquid crystal forming a pixel by a driving signal supplied from a path (not shown), and
The light modulation is performed by controlling the transmission of each color light incident through the reference numeral 5. The light beams of the respective colors RGB modulated by the liquid crystal panel unit 48 are magnified by the projection lens 49 via the polarizing plate 47 and projected on the screen 50. The total reflection mirror 44 is not necessarily required in the illustrated configuration because it is arranged in consideration of miniaturization of the optical system. Therefore, it is also possible to configure so that each color light separated by the color separation unit 43 is directly incident on the liquid crystal panel unit 48.

Here, the configuration of the liquid crystal panel 46 and the optical paths of the RGB color lights will be described with reference to the schematic diagram of FIG.
On the incident surface of the liquid crystal panel 46, for example, a TFT (Thin Film Trangi) for driving liquid crystal in order to correspond to a high definition panel.
ster) A microlens array 62 in which microlenses 62a, 62a, 62a,... is formed in a counter substrate of the substrate, that is, in a stage preceding the liquid crystal unit 61.
The R, G, and B light rays condensed by the microlenses 62 a are optically modulated by the liquid crystal unit 61, and are subjected to black matrix 63.
The light is emitted from the pixels P which are the gaps of 63, 63,... To form an image. Note that, in this figure, as an example, each color light of RGB that is incident on one micro lens 62a is shown. The distance F indicates the focal length (principal point to focal point) of the micro lens 62a, and the distance d indicates the distance from the principal point of the micro lens 62a to the emission portion of the pixel.

The R light (broken line) separated by the color separation unit 43,
G light (solid line) and B light (dashed line) are 2δ
The light enters the microlens 62a at an angle of?, And is condensed and emitted to the pixel P corresponding to the microlens 62a. That is, although not shown, each micro lens 62a, 62a, 62a.
When the light, the G light, and the B light enter, the R, G, and B color lights are condensed and combined for one pixel P, respectively. Therefore, a color image can be formed without having to provide a color filter on the liquid crystal panel 46.

As described above, by providing the microlens array 62 in front of the liquid crystal unit 61, the light collection efficiency can be increased, and the effective aperture ratio can be improved by reducing the absorptivity when no color filter is used. Is achieved.
Further, since color synthesis using an optical element such as a prism is not required, for example, using three liquid crystal panels corresponding to RGB colors, light from a lamp is separated for each color, and then light modulation is performed. Compared with a three-panel liquid crystal projector device that forms a color image by combining each color light, it is possible to obtain luminance comparable to that of a three-panel liquid crystal projector device.

[0008]

By the way, in order to improve the brightness of an image, it has been considered to effectively use light output from a lamp. Normally, light emitted from a lamp has two orthogonal polarization planes, and these polarization planes are generally a P-polarized component (hereinafter, referred to as P-wave) and an S-polarized component (hereinafter, referred to as S-wave). ). That is, by using the polarization conversion means, the P wave and the S wave are separated from the random polarized wave (P wave + S wave) emitted from the lamp, and then, for example, the S wave is converted into the P wave,
By forming an image using only waves, light utilization efficiency is achieved.

For example, in a three-panel type liquid crystal projector,
There are known an integrator for effectively using light output from a lamp without unevenness, and an optical system using polarization conversion means for converting a polarization component of light. In the optical system of such a three-panel type liquid crystal projector, since an image is formed by using a combination of light of each color, there is no need to use parallel light.

However, in the single-panel type liquid crystal projector described with reference to FIGS.
Since the incident angle of light with respect to a is restricted, the color separation unit 4
The light incident on 3 requires parallelism. For this reason, if an integrator or a polarization conversion unit is used, it is difficult to irradiate the irradiated surface such as the color separation unit 43 with parallel light due to its structure. Further, when the integrator and the polarization converter are used in combination, the light amount can be increased, but there is a problem that the parallelism of light cannot be obtained.

In a conventional liquid crystal projector,
For example, when the liquid crystal panel unit 48 is irradiated with the parallel light as it is, for example, due to the configuration of the reflector 40a, the field lens 41, and the like, the image forming area of the liquid crystal panel is displayed, for example, with respect to the substantially circular lamp irradiation area. For example, the rectangle has a 4: 3 aspect ratio corresponding to the image. That is, the light radiated to portions other than the image forming region (for example, the outer frame of the liquid crystal panel) is wasted without being used for image formation.

Further, since the light not used here does not contribute to the brightness of the formed image and also causes heat to be generated inside the apparatus housing, it is provided with a cooling means (a large fan or the like). The need arises. This increases the cost and increases the size of the projector device itself.

Further, the area of the emission part of the polarization conversion means is formed to be equal to the area of, for example, a liquid crystal panel. However, the area of the incidence part is, for example, about half the area of the emission part because of its structure. I have. That is, there is a problem that it is difficult for the light from the lamp to efficiently enter the incident portion formed with a smaller area than the liquid crystal panel.

[0014]

In order to solve the above problems, the present invention has at least a light modulating means for modulating light emitted from a lamp to form an image, and a light modulating means for forming an image by the light modulating means. As a lighting device used in a display device provided with a projection unit for projecting a projected image, in a state where light emitted from the lamp is parallel light, an irradiation area thereof corresponds to a diagonal size of a surface to be irradiated. Light collecting means is provided.

According to the present invention, parallel light corresponding to an area smaller than the diameter of the opening of the lamp can be formed. Therefore, light in a region that could not be used conventionally can be effectively used, and for example, an irradiated surface such as a liquid crystal panel can be efficiently irradiated.

[0016]

Embodiments of the present invention will be described below. FIG. 1 is a schematic diagram illustrating a configuration example of a lighting device according to the first embodiment. The lamp 1 has a light emitting unit 3 disposed in a reflector 2 having a parabolic surface. The light emitted from the light emitting unit 3 is reflected by the inner surface of the reflector 2,
The light is emitted forward from the opening as, for example, parallel light.
The opening of the reflector 2 has a diameter of, for example, φa, that is, light emitted from the reflector 2 can illuminate an area of a diameter of φa. A condensing lens 4 is disposed in front of the lamp 1 as a converging convex lens, and condenses the light output from the reflector 2 on the incident surface of the concave flat lens 5. The concave flat lens 5 can convert the light from the condenser lens 4 into parallel light that can irradiate, for example, a region having a diameter φb and emit the parallel light.

Here, the condenser lens 4 is set to f1 (f1>
0), if the concave flat lens 5 is f2 (f2 <0), and if these lenses are arranged at a distance L, the two expressions of f1−L = −f2 and f1> L are satisfied. Thereby, it becomes afocal in the paraxial region, and parallel light can be emitted. That is, the concave flat lens 5 is disposed before the focal length of the condenser lens 4.

Diameter φ of parallel light emitted from concave flat lens 5
As described later, b has a length corresponding to a diagonal line of a surface to be irradiated such as a liquid crystal panel. Thereby, it is possible to form light that is an efficient irradiation area on the irradiation surface by the concave flat lens 5. That is, the condenser lens 4 and the concave flat lens 5 are configured to be able to convert light from the lamp 1 into parallel light having a diameter substantially equal to the diagonal line of the surface to be irradiated.

As described above, the parallel light emitted from the lamp 1 is condensed on the concave flat lens 5 by the condensing lens 4 and is converted into the parallel light again by the concave flat lens 5.
It is possible to form parallel light capable of illuminating an area having a diameter φb smaller than the diameter φa of the reflector 2 without losing the light amount.

FIG. 2 is a view for explaining the relationship between the light beams having the diameters φa and φb shown in FIG. 1 and the area of a surface to be irradiated such as a liquid crystal panel irradiated with the light beams. FIG.
(A) is an irradiation area 6 of a light beam having a diameter φa and an irradiation surface 7.
However, as can be seen from this figure, the irradiation area 6 of the light emitted from the lamp 1 with the diameter φa is large with respect to the irradiated surface 7.
Is collected. 2 by the concave flat lens 5.
Illumination area 8 having a diameter φb as shown in FIG.
To form As a result, the diameter φb of the illumination area 8 and the diagonal line of the illuminated surface 6 are made to substantially coincide with each other, and the useless light is reduced as compared with the case shown in FIG. Can be planned.

FIG. 3 is a diagram for explaining an example in which the surface to be illuminated is, for example, an incident portion of a polarization conversion block configured to convert a P wave into an S wave. The polarization conversion block 10 shown in FIG. 1 has a structure in which a transparent member such as glass is combined, and P + emitted from a condenser lens 4 and a concave flat lens 5 (not shown).
S wave light (black arrow) is converted to P wave (dashed-dotted arrow) and S wave.
Waves (broken arrows) are split into S-waves and then P-waves.

The width Ta (horizontal direction) of the incident portion 11 of the polarization conversion block 10 corresponds to the width Ta in the longitudinal direction of the irradiated surface 6 shown in FIG. This width T
“a” is set to a half width in the longitudinal direction of the liquid crystal panel to be irradiated (not shown). Outside the entrance 11, a mask 12 configured by, for example, a mirror or the like to block light not required by the polarization conversion block 10,
12 are provided.

The P + S wave incident from the incidence section 11 is separated into a P wave and an S wave by a polarization beam splitter 13 serving as a polarization splitting means. The P wave passes through the polarization beam splitter 13 and goes straight to a polarization conversion block. It is emitted from 10. On the other hand, the S wave is reflected by the polarization beam splitter 13 and reaches the mirrors 14 and 14. Then, the light is reflected forward by the mirrors 14 and 14 and the λ / 2 plates 15 and 1 are reflected.
5 to be converted into a P-wave and emitted. Therefore, for example, only the P wave is emitted from the emission section 16 of the polarization conversion block 10.

The emission section 16 has, for example, a width in the horizontal direction that is about twice (2Ta) the incidence section 11, and can emit, for example, a P-wave with an area about twice as large as the incidence on the incidence section 11. Have been able to. In addition, the area of the emission part 16 is
For example, it corresponds to the area of the surface to be illuminated such as a liquid crystal panel, so that efficient emission from the emission section 16 can improve the brightness of the image. in this way,
The polarization conversion block 10 aligns the polarization plane of the incident light so as to correspond to the characteristics of a polarizing plate included in a liquid crystal panel (not shown), and can emit the light with an area about twice as large as that at the time of incidence. It has been like that.

In the present invention, for example, the condenser lens 4 and the concave flat lens 5 shown in FIG.
The irradiation area of the light from the light source is reduced and concentrated in the vicinity of the incident part 11, so that the light that has been blocked by the masks 12 and 12 can be guided to the incident part 11.

FIG. 4A is a diagram schematically showing the relationship between the incident portion 11 of the polarization conversion block 10 and the irradiation area of the lamp 1. FIG. 4 shows an example in which the arrow H is indicated, for example, in the horizontal direction, and the optical elements such as the polarization beam splitters 13 and 13 are arranged side by side in the horizontal direction.
The diameter φb of the irradiation area 8 shown by a broken line is configured to substantially coincide with the diagonal line of the incident part 11. Of the light applied to the irradiation area 8, the light incident on the incident portion 11 corresponding to the central portion is used, but is subjected to P / S conversion as described with reference to FIG. As shown in the figure, the light is emitted from the emission unit 16 having a horizontal width of 2 Ta.

Thus, even in the case where the diameter of the lamp 1 is larger than the diagonal line of the incident part 11, the area corresponding to the diagonal line of the incident part 11 is irradiated by the condenser lens 4 and the concave flat lens 5. Collimated light can be formed. In this case, the diameter φb of the parallel light and the incident portion 11
By making the diagonal lines substantially coincide with each other, parallel light can be incident most efficiently over the entire area of the incident portion 11. Further, since the parallel light incident on the incident portion 11 is formed so as to concentrate the light from the lamp 1, P / S conversion is performed without losing the light amount to effectively use the light and improve the brightness. It is possible.

Further, the optical elements such as the above-mentioned polarization beam splitters 13 and 13 are arranged side by side in the vertical direction with the arrow H shown in FIG.
Is constructed as shown in FIGS. 5A and 5B. The polarization conversion block 17 shown in FIG.
In the figure, the diagonal line of the incident portion 18 corresponds to the diameter φbr of the irradiation area 8r, the width in the vertical direction is Tbr, and the masks 19, 19 are formed above and below it. As a result, as shown in FIG. 5B, the width in the vertical direction is 2 Tbr.
The P / S-converted light is emitted from the emission unit 20 described above as in the case shown in FIG. Also in this case, the light of the lamp 1 concentrated on the entrance 18
The light is emitted from the emission unit 20 having an area twice as large as that of the light emitting unit 8.

In the case of the single-panel type liquid crystal projector described with reference to FIG. 11, the separation of each color of R, G, and B performed by the color separation unit 43 is performed at a predetermined angle in the horizontal direction. Parallelism is required. However, although the vertical parallelism depends on the conditions such as the pixel arrangement of the liquid crystal panel, strict parallelism is required especially when the pixels are arranged by vertical stripes. is not. Therefore, it is conceivable that the light irradiating the area outside the liquid crystal panel is refracted by a light deflecting unit such as a lens, and is effectively used by irradiating the light inside the liquid crystal panel.

FIG. 6 is a diagram showing an example of the configuration of an illumination device provided with a light deflecting means as a second embodiment. Lamp 1a
Has a light emitting unit 3a disposed in the reflector 2a,
The diameter of the opening of the reflector 2a is φa, and the reflector 2a is configured to focus the emitted light on the concave flat lens 5 with an irradiation area of the diameter φb. The concave flat lens 5 converts the light incident from the lamp 1a into parallel light and emits it. In the example shown in this figure, a condensing lens 21 is arranged on the emission side, and the parallel flat light converted by the concave flat lens 5 is used. The light is refracted so as to concentrate on the irradiated surface 7.

FIG. 7 is a plan view of the condenser lens 21. FIG. The central portion is configured as, for example, a concave portion 21a, and the width in the vertical direction is equal to the width in the vertical direction of the irradiated surface 7, and the parallel light incident from near the center of the concave flat lens 5 is used as it is. Emitted as parallel light. Inclined portions 21b, 21 formed at both ends of the concave portion 21a
“c” is configured to have an inclination angle at which light emitted from the vicinity of the peripheral portion of the concave flat lens 5 can be refracted and incident on the irradiated surface 7. The central portion of the condenser lens 21 corresponding to the concave portion 21a may be formed as a flat surface, and does not necessarily need to be formed as a concave shape.
For example, a plane as shown by a broken line between the inclined portions 21b and 21c shown in FIG. 6 may be configured to have a trapezoidal shape as viewed from the side.

The irradiation area when the condenser lens 21 is arranged as shown in FIG. 6 will be described with reference to FIGS. FIG. 8A shows the irradiation area 8 when the condenser lens 21 is not used. In this case, light in a region other than the liquid crystal panel 5 indicated by hatching is wasted, but when the condenser lens 21 is disposed, as shown in FIG. Then, the light in the lower region can be refracted and incident on the irradiated surface 7 so as to be superposed.

By constructing an optical system by combining the concave flat lens 5, the polarization conversion block 17, and the condenser lens 21, a synergistic effect of each optical element can be obtained, and an image with higher luminance can be obtained. Will be able to do it. In this case, by arranging the polarization conversion block 17 immediately before the liquid crystal panel, an effective configuration can be obtained in terms of the light condensing effect of the irradiation area and, for example, the superposition in the vertical direction.

FIG. 9 shows an optical system of a liquid crystal projector constructed by combining the concave flat lens 5, the polarization conversion block 17, and the condenser lens 21, for example, as viewed from above. In the optical system shown in this figure, after the light emitted from the reflector 2 is converted into parallel light by the concave flat lens 5, it is condensed by the condensing lens 21 as in the case shown in FIG. Here, the light is made to concentrate on the incident part 18 of the polarization conversion block 17 disposed after the color separation part 22. And the polarization conversion block 1
The light emitted from 7 is light-modulated by the liquid crystal panel 23 corresponding to the liquid crystal unit 48 shown in FIG. 11 and projected by the projection lens 24.

FIG. 10 shows an irradiation area at the incident portion 18 of the polarization conversion block 17.
As shown in the figure, light that should originally enter above and below the incident portion 18 (to the masks 19, 19) is refracted,
As shown by hatching, they are superimposed on the incident part 18. Thus, a synergistic effect is obtained in that the light of the lamp is concentrated on the incident portion 18 by the concave flat lens 5 and the condensing lens 21 and the light can be effectively used by the P / S conversion by the polarization conversion block 17. be able to.

[0036]

As described above, according to the present invention, of the light output from the lamp, the light radiated to a region which could not be used conventionally can be effectively used. Efficient irradiation can be performed on a surface to be irradiated such as a liquid crystal panel. Thereby, the luminance per irradiation area can be improved, and an image with higher luminance can be formed. Also, the present invention can be realized easily and at low cost, since the structure of the lamp and the surface to be irradiated can be kept as it is and a lens serving as a light condensing means is provided in front of the lamp.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating a configuration of a lighting device according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating an irradiation area of the illumination device shown in FIG.

FIG. 3 is an explanatory diagram in a case where an incident portion of a polarization conversion block is a surface to be illuminated.

FIG. 4 is a diagram illustrating a relationship between an incident portion of a polarization conversion block and an irradiation area of a lamp.

FIG. 5 is a diagram illustrating a relationship between an incident portion of a polarization conversion block and an irradiation area of a lamp.

FIG. 6 is a diagram illustrating a configuration of a lighting device according to a second embodiment of the present invention.

FIG. 7 is a front view of the condenser lens shown in FIG.

8 is a diagram illustrating an irradiation area of the lighting device shown in FIG.

FIG. 9 is a diagram illustrating a configuration example when the present invention is applied to a single-panel type liquid crystal projector device.

FIG. 10 is a diagram illustrating an irradiation area of a lamp at an incident portion of the polarization conversion block shown in FIG. 9;

FIG. 11 is a diagram illustrating an example of an optical system of a single-panel type liquid crystal projector device.

12 is a diagram illustrating the configuration of the liquid crystal panel illustrated in FIG. 11 and optical paths of RGB color lights.

[Explanation of symbols]

1 lamps, 2 reflectors, 3 light emitting units, 4, 21
Condensing lens, 5, concave flat lens, 6, 8, 8r irradiation area, 7 irradiated surface, 10, 17 polarization conversion block, 1
1,18 entrance part, 16,20 exit part

Claims (4)

[Claims] 1. A display device comprising: at least a light modulating unit that modulates light emitted from a lamp to form an image, and a projecting unit that projects an image formed by the light modulating unit. An illuminating device, comprising: a illuminating device provided with a condensing unit that can make an irradiation area correspond to a diagonal size of a surface to be illuminated in a state where light emitted from the lamp is parallel light. 2. A light deflecting means configured to deflect light emitted from the light condensing means and applied to a region not incident on the surface to be irradiated, and to irradiate the inside of the surface to be irradiated. The lighting device according to claim 1, further comprising: 3. A polarization converting means for converting the light emitted from the lamp into a first polarized light and a second polarized light after converting the light into a first polarized light and a second polarized light,
2. The illumination device according to claim 1, wherein the condensing unit is configured to convert an irradiation area of the lamp into an area corresponding to a diagonal size of the polarization conversion unit. 3. 4. The lighting device according to claim 3, wherein said polarization conversion means is disposed immediately before said light modulation means.