JP2001056461A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display device in which a transmission type liquid crystal display element having excellent display quality is used by improving the viewing angle characteristics. SOLUTION: The liquid crystal display device is equipped with a liquid crystal display element 2 having a pair of glass substrates 41, 42 with transparent electrodes on the inner sides facing each other, having a liquid crystal material injected between the substrates and having a plurality of pixels, with a pair of polarizing means 61, 62 disposed on the observer side and the surface light source side 1 of the liquid crystal display element 2, respectively, and with a surface light source 1. The peak direction of the contrast of the liquid crystal display element 2 is present at a specified angle from the normal line direction of the plane and is almost coincident with the chief ray direction of the emitted light from the surface light source 1. The device is also equipped with a first optical means to diffuse the emitted light from the liquid crystal display element 2 to the observer's side of the liquid crystal display element 2. The surface light source 1 is composed of one or more light source parts 11 and a light guide part 12. The light guide part 12 has one or more incident faces where the light from the light source 11 enters and an exit face where the light exits. The peak direction of the contrast of the liquid crystal display element 2 is present at specified two angles from the normal line of the plane and is almost coincident with the chief ray direction of the emitted light from the surface light source 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmissive liquid crystal display device, and more particularly to an optical device having improved viewing angle dependency and a liquid crystal display device using the transmissive liquid crystal display device.

[0002]

2. Description of the Related Art A liquid crystal display device is a CRT (Cathode).
(Ray Tube), PDP (Plasma Dis)
(Play Panel) or EL (Electr)
o Luminescence) is a display device representing a flat panel display. In particular, a transmissive liquid crystal display device is lightweight, thin, and has low power consumption, so it is used for OA equipment, in-vehicle television, car navigation, and video cameras. Widely used for monitors and the like.

However, a major problem is that viewing angle dependency is large. The viewing angle dependency is, for example, when observing a display device from an oblique direction at a certain angle or more, an object that should be displayed in black looks whitish or the gradation is inverted, so that the contrast is reduced or the contrast is reduced. This is a state in which the inversion occurs and the observer cannot accurately read the display image. A case where the angle range in which the image can be normally observed is narrow is referred to as a large viewing angle dependence of the display device.

There are various reasons for the dependence of the viewing angle on the liquid crystal molecules, such as the twisting of the liquid crystal molecules (the starting position of the liquid crystal molecules determined by the helical direction and the rubbing direction) and the refractive index anisotropy of the liquid crystal molecules. (A difference in retardation with respect to the traveling direction), characteristics due to the characteristics of the polarizing plate (selectivity of the light vibration direction), and characteristics due to the directivity of the surface light source.

Generally, in a transmission type liquid crystal display device,
In consideration of the above viewing angle dependence, the most visible position of the display is designed to be within the normal use range of the observer,
For example, a design is made to increase the contrast in the normal direction at the center of the screen or in a slightly downward direction as compared with the surrounding area.

However, even in this configuration, the viewing angle range is not sufficient. In particular, a liquid crystal display device has a large viewing angle dependency in the vertical direction of the screen, and various methods have been conventionally proposed to solve this problem. I have. For example, JP-A-10-10513, JP-A-6-27454, JP-A-7-239467, JP-A-8-122
No. 757, Japanese Patent Application Laid-Open No. 9-152606, and the like have been proposed.

The prior art has various problems. Japanese Patent Application Laid-Open No. 10-10513 discloses a TN between a substrate on which a TFT element is formed and a substrate on which a color filter is formed.
On the viewer side of the transmissive liquid crystal display panel where the liquid crystal is sandwiched,
By disposing a retardation film having optically negative characteristics with respect to the TN liquid crystal and further disposing a light diffusion layer,
Liquid crystal display devices with improved viewing angle dependence have been proposed.
In this conventional example, the viewing angle dependency is improved by correcting the optical characteristics of the arrangement of liquid crystal molecules with a retardation film.Furthermore, light emitted from the liquid crystal display panel uses a lens film as a light diffusing means. By using this, the viewing angle range is widened. However, in order to efficiently receive and diffuse the light emitted from the liquid crystal display element, the arrangement position of the diffusion layer (lens), the focal length of the lens, and the light receiving angle characteristics of the lens are important. No properties relating to these are disclosed.

Japanese Patent Application Laid-Open No. Hei 6-27454 proposes an optical element for a liquid crystal display having improved vertical viewing angle characteristics by arranging a lenticular lens having a light shielding layer selectively formed on the front surface of the liquid crystal display. I have. In this prior art liquid crystal display device, as shown in FIG. 24, a stripe-shaped light-shielding layer 72 is selectively provided on a transparent plastic substrate 71, and a transparent plastic is further formed thereon to form a semicircular section. Lenticular lens 7 having an array of unity lenses 73 in the shape of a bunch
Place. In this case, the unit lens array surface is the light shielding layer 7.
2 is the surface 74 of the plastic substrate 71 on which the irregularities are formed, and the uneven surface is the surface 75 of the Kamaboko-shaped lens group;
Further, the first material layer is a plastic layer 76 forming the Kamaboko-shaped lens, and the second material layer is an air layer (not shown here) on the Kamaboko-shaped lens. However, forming a light-shielding layer selectively at the boundary between lenses as in this conventional example requires forming the light-shielding layer only on a selected portion by using a photolithography process, an evaporation method, or the like. It becomes complicated and it is very difficult to reduce the cost of the device. In addition, in order to form a light-shielding film by the above method, it is necessary to select a substrate having excellent solvent resistance and heat resistance, and it is presumed that the main material is limited.

Japanese Patent Application Laid-Open No. 7-239467 proposes a liquid crystal display device in which a prism lens film is disposed between a liquid crystal panel and a surface light source, and a wave lens film is disposed in front of the liquid crystal panel. However, even in this conventional example, nothing is disclosed about various characteristics of the lens film for improving the viewing angle.

In Japanese Patent Application Laid-Open No. Hei 8-122575, a polymer thin film for diffusing incident light in a specific direction is arranged on the front surface of a liquid crystal display panel, and light emitted from a surface light source is transmitted at a diffusion angle of the polymer thin film. There has been proposed a liquid crystal display device having the same configuration. As shown in FIG. 25, this prior art liquid crystal display device has a pair of substrates 84 provided with an electrode 87 for applying an electric field for each pixel and an alignment film 88 on its inner surface.
And a liquid crystal cell 82 having a liquid crystal layer 85 sandwiched between a pair of substrates 84, a polarizing plate 86 attached to the front and rear sides of the substrate 84 of the liquid crystal cell 82, and a light substantially perpendicular to the liquid crystal layer 85. It comprises a light introducing means 81 for guiding the light and a light diffusing means 83 for diffusing light emitted from the liquid crystal cell 82. Note that the lighting unit 89 may be provided. However, in this conventional example, a scattering film is used for the diffusion layer, and the distance between the diffusion layer and the pixel formed on the liquid crystal display panel is separated by the thickness of the opposing substrate. It has the problem of occurring. In general, as a scattering film, a film that irregularly reflects and scatters light by forming an uneven shape on a film surface, a film that disperses light by dispersing particles in a film, or a diffraction grating formed in a film A device that diffusely reflects light in a specific direction is known. However, when any of the scattering films is used, when the distance between the surface on which the image is displayed and the surface on which the scattering film is arranged is large, unnecessary scattered light is generated, and the image is blurred. As a result, the contrast of the image is reduced, and the display quality is significantly reduced.

Japanese Patent Application Laid-Open No. 9-152606 discloses a liquid crystal display panel in which the viewing angle characteristic is improved by diffusing two principal ray directions emitted from a surface light source in which two light sources are arranged by an optical film. . As shown in FIG. 26, this prior art liquid crystal display device includes a liquid crystal cell 92 in which liquid crystal molecules are twisted between a pair of transparent substrates 94, and a pair of front and back polarizing plates 96 arranged therebetween. 9, a backlight 91 disposed behind the liquid crystal display element 9, and a diffusion plate 93 provided on the front side of the liquid crystal display element 9.
Is a case 91 in which the surface facing the liquid crystal display element 9 is open.
0, the light guide plate 9 facing the back surface of the liquid crystal display element 9.
The light guide plate 912 is provided with opposing light source lamps 911 on both end surfaces of the light guide plate 912, and a prism sheet 914 is disposed on the surface side of the light guide plate 912. More specifically, a scattering film is used as an optical film, and the viewing angle characteristic is improved by matching the angle characteristic of the scattering film with the intensity of light emitted from a light source. Note that the surface normal direction (H) and the viewing angle direction (F)
It is shifted by the angle θ. However, also in this conventional example, since the distance between the scattering film and the pixel formed on the liquid crystal display element is separated by the thickness of the counter substrate,
There is a problem that image blur occurs due to parallax.

[0012]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to use a transmission type liquid crystal display device having excellent display quality by improving the viewing angle characteristics. It is an object of the present invention to provide a liquid crystal display device.

[0013]

According to the present invention, there is provided a liquid crystal display device having a plurality of pixels formed by a pair of glass substrates having a transparent electrode on an inner surface side and facing each other and having a liquid crystal material injected therebetween. In a liquid crystal display device comprising a pair of polarizing means and a surface light source arranged on the viewer side and the surface light source side of the liquid crystal display element, respectively, the peak direction of contrast of the liquid crystal display element is a surface normal. A first optical means which is at a predetermined angle from the direction, substantially coincides with the principal ray direction of the light emitted from the surface light source, and diffuses the light emitted from the liquid crystal display element to the viewer side of the liquid crystal display element. It is a liquid crystal display device provided with. Thereby, when the light emitted from the surface light source passes through the liquid crystal display element, there is no reduction in contrast, and the light is diffused by the first optical means, so that the viewing angle characteristics of the liquid crystal display device can be improved.

Further, according to the present invention, the surface light source comprises at least one light source unit and a light guide unit, and the light guide unit has at least one incident surface on which light from the light source unit is incident. An emission surface for emitting light, and the peak direction of the contrast of the liquid crystal display element is in two directions at a predetermined angle from the surface normal direction, and the direction of the principal ray of the light emitted from the surface light source. It is a liquid crystal display device that almost matches. This makes it possible to provide a liquid crystal display device in which the reduction in contrast is small and the viewing angle characteristics are improved.

According to the present invention, the first optical means comprises a plurality of lens arrays formed parallel or perpendicular to the pixels formed on the liquid crystal display element, and the pitch of the lens arrays is set to P1. And the pitch P of the lens array
This is a liquid crystal display device formed so as to satisfy (1/20) × P2 ≦ P1 <P2 when a pixel pitch of a liquid crystal display element formed in parallel with one direction is P2. This allows
It is possible to prevent the occurrence of dark areas in the observation range, and to provide an image with high display quality. Hereinafter, the details will be described.

In general, a liquid crystal display element forms color filters of three primary colors of red (R), green (G), and blue (B) for each pixel, and colors light transmitted through the pixel to perform color display. Is going. There are various arrangement patterns of R, G, and B pixels, and representative examples include a delta arrangement shown in FIG. 18A and a stripe arrangement shown in FIG. 18B. And a black matrix (hereinafter referred to as BM) around the pixel.
Described). Generally, the pixel pitch refers to a distance from BM of adjacent pixels to BM, and is called a horizontal pitch Ph and a vertical pitch Pv depending on the arrangement direction.

The number of pixels of the liquid crystal display element and the size of the pixel vary depending on the size of the display element. For example, a 15-inch liquid crystal display element has a stripe arrangement of 640 × horizontal pixels.
In the case of (R, G, B) × the number of vertical pixels 480, the pixel pitch is approximately 0.159 mm in the horizontal direction Ph and approximately 0.476 mm in the vertical direction Pv, and the BM width P3 formed between pixels is 0. 01 mm.

By the way, when a lens is made to correspond one-to-one to the above-described pixel, for example, when the pixel pitch Pv and the lens pitch are arranged to match, as shown in FIG.
The observer sees the dark area where only the BM surface 193 formed between the pixels is observed, and the display quality deteriorates. Further, the pattern formed by the lens 191 and the pixel pattern (Pv in this drawing) formed on the liquid crystal display element 190 and formed in a direction parallel to the lens interfere with each other to generate moire fringes. As a result, the display quality is significantly reduced.
If the lens pitch P1 is designed to be larger than the pixel pitch P2, the observer will observe a plurality of pixels at the same time, and image blur will occur.

On the other hand, by making the lens pitch P1 smaller than the pixel pitch P2 as in the present invention,
One pixel can be observed with a plurality of lenses, and generation of a dark area can be reduced. The direction in which the viewing angle is improved changes depending on the direction in which the lens is formed. For example, if it is desired to improve the viewing angle in the vertical direction of the screen, the lens may be arranged in parallel with the vertical pitch Pv of the pixels. In this case, the lens pitch P1
Is smaller than the pixel pitch Pv, the occurrence of a dark area can be reduced. When it is desired to improve the viewing angle in the horizontal direction of the screen, the lenses are arranged in parallel with the horizontal pitch Ph of the pixels, and in this case, the pitch P1 of the lenses may be formed smaller than the horizontal pitch Ph of the pixels. In general, when the lens pitch is reduced, the light condensing power of the lens is weakened, so that light emitted from the pixel cannot be sufficiently diffused.
As the effect of improving the viewing angle decreases, light diffraction occurs on the lens forming surface, and an iridescent image is observed. In order to improve the viewing angle and prevent the diffraction phenomenon, the lens pitch P1
Is preferably at least 1/20 of the pixel pitch P2.

In the present invention, the pitch of the lens array is P1, the focal length is f, the distance in air from the plane on which the lens array is arranged to the pixels formed on the liquid crystal display element is d, and the pixel pitch is Is P2, and the pixel pitch P
The width of the black matrix BM formed in two directions is P3
, The width x formed on the pixel corresponding to the pitch width of the lens array around the focal length is x = P1 × |
(D−f) | / f, and 0 ≦ x ≦ (1.5 ×
A liquid crystal display device satisfying P2). Further, if the width x is P
By satisfying 3 ≦ x ≦ P2, a better effect can be obtained.

The operation of this configuration will be described below. When a plurality of lenses 201 are arranged for one pixel formed in a liquid crystal display element, the BM is required as shown in FIG.
It is possible to observe, as an image, an overlap between a region for observing the surface 203 and a region for observing the pixel opening 202 (a region for displaying an image other than the BM plane). As a result, FIG.
Can be reduced.

As shown in FIG. 20 (b), the lens 201 has a focal length f shorter than a distance d to a plane on which the pixels are arranged, so that the lens 201 is focused on the focal point.
Light emitted from the width x formed on the pixel corresponding to the pitch width of the lens array can be diffused, and the dark area can be reduced. Further, at this time, by designing the width x to be larger than the BM width P3 formed in the pixel, the light emitted from the opening 202 of the pixel can be surely diffused, so that the light outside the dark area can be diffused and the viewing angle can be improved. I can do it. However, since this configuration employs a configuration in which light emitted from an area wider than the BM surface is diffused by a lens, blurring of an image (double imaging) is promoted. For this reason, the width x is preferably set to 1.5 times or less the pixel pitch, and more preferably, by setting the width x to a pitch P2 of 1 pixel or less.
Image blur can be suppressed.

Further, the present invention is a liquid crystal display device which satisfies the condition of 5 ° ≦ θ1 ≦ 40 ° when the light receiving angle of the lens array is θ1. The light receiving angle θ1 of the lens described in this specification is measured by a measuring instrument as shown in FIG.
By using (Photo-AG1200 manufactured by Otsuka Electronics Co., Ltd.), parallel light having a spread of ± 3 ° as incident light 251 is converted into yz in a direction perpendicular to the xy plane in which the lens 253 is formed. The light was incident on the plane at an angle of ± θ, and at this time, the intensity of light emitted in the front direction of the lens 253 was received by the light receiver 252, and the angle at which the intensity became almost zero was measured.

FIG. 21B shows the measurement result of the light receiving angle θ1 of the lens. For example, a lens having a light receiving angle θ1 of ± 30 ° shows the characteristic indicated by the symbol ▲ in FIG. FIG.
1 (b) shows the incident angle θ2 of the incident light on the horizontal axis, and the relative brightness of the light receiving brightness of the light receiver 252 on the vertical axis, and uses the light receiving angle θ1 of the lens as a parameter. 2
It is the result of having measured the case of 0 degrees, 30 degrees, 40 degrees, and 60 degrees.

In order to determine the degree of diffusion of the lens, a measuring instrument (Photo-AG120 manufactured by Otsuka Electronics Co., Ltd.) is similarly used.
0), the lens 253 is used as shown in FIG.
Parallel light 251 is incident from the front direction of
The light intensity of the diffused light in the direction of ±±
Was measured and determined.

The degree of diffusion of the lens will be described with reference to FIG. FIG. 22B is a diagram showing how light incident from the front of the lens spreads after passing through the lens when the light receiving angle θ1 of the lens is changed. For example, when the light receiving angle of the lens is ± 30 °, light can be diffused to a direction of approximately ± 60 ° as shown by the mark ▲ in the figure. FIG.
(b) shows the diffusion angle θ on the horizontal axis and the intensity of the diffused light on the vertical axis. The light receiving angle θ1 of the lens is used as a parameter, and the angles are 10 °, 20 °, 30 °, 40 °, and 60 °, respectively. It is the result of having measured the case of.

Next, the change in the viewing angle characteristic and the brightness of the liquid crystal display device when the light receiving angle θ1 of the lens is changed will be described. In this measurement, as shown in FIG. 23, the liquid crystal display device 260 including the surface light source device 263, the TN liquid crystal display element 262, and the lens sheet 261 having different light receiving angles θ1 is rotated with respect to the yz plane, A luminance meter (manufactured by Topcon Co., Ltd.)
BM-5A) 264 was used to determine the contrast (luminance during white display / luminance during black display).

FIG. 5A shows the relationship between the light receiving angle θ1 of the lens and the brightness (front luminance) in the front direction of the liquid crystal display device. The smaller the light receiving angle θ1 of the lens is, the less the brightness decreases in the front direction, and the wider the light receiving angle θ1 of the lens is, the lower the brightness is in the front direction. The light receiving angle θ1 of the lens is 40
If the angle is larger than °, the brightness in the front direction decreases
Since the load on the surface light source device is increased in order to reduce the liquid crystal display mode to about 0.4 times and maintain the same level of brightness as the conventional one, the light receiving angle θ1 of the lens is a practical range. It is preferably 40 ° or less.

Next, FIG. 5B shows the light receiving angle θ1 of the lens.
And a viewing angle range θ2 (in the present specification, an angle range in which a contrast of 10 or more can be ensured). Note that the light receiving angle θ1 of the lens in the figure of 0 ° indicates the characteristics of the conventional TN liquid crystal display mode in which no lens is disposed. When a lens sheet 261 having a different light receiving angle θ1 of the lens is arranged in the liquid crystal display device, the viewing angle range θ is set according to the light receiving angle θ1 of the lens.
2 (in this specification, an angle range in which a contrast of 10 or more can be ensured) changes. More specifically, when the light receiving angle θ1 of the lens is increased, the diffusion effect becomes stronger,
The viewing angle range θ2 widens, but the light receiving angle θ1 of the lens is 40 °
Above, the viewing angle improvement effect is saturated. Also, it has been found that when the light receiving angle of the lens is less than 5 °, there is almost no effect of modifying the viewing angle and the viewing angle dependency is not improved.

As described above, the light receiving angle θ1 of the lens
Is an important parameter for improving the viewing angle, and it is understood that the value is preferably 5 ° or more and 40 ° or less in consideration of the balance between the effect of improving the viewing angle and the decrease in luminance in the front direction.

Further, according to the present invention, the light shielding means is formed on the entire surface of one or both of the surface on which the lens array is formed and the surface opposite to the surface on which the lens array is formed. It is a liquid crystal display device. Thereby, light having a shallow angle (stray light) totally reflected on the lens surface can be prevented from being irregularly reflected, and reflection from the outside light side can be prevented, so that the display quality of the liquid crystal display device can be improved. Further, since the light-shielding layer is formed on the entire surface of the lens surface or the opposing surface, the light-shielding layer can be formed easily and inexpensively.

According to the present invention, there is provided a liquid crystal display device wherein the lens array is formed on a side face of an observer of a substrate arranged opposite to the liquid crystal display element. Thereby, the distance from the surface on which the lens is arranged to the pixel can be shortened, and image blur due to parallax can be prevented. In addition, since the focal length of the lens itself can be designed to be short, as a lens with high focusing power,
A bright liquid crystal display device can be obtained.

Further, according to the present invention, the first optical element is formed on the observer side of the substrate opposed to the liquid crystal display element, and scattered particles are contained between the substrate and the color filter. A liquid crystal display device formed of an organic material. Thereby, the distance between the scattering surface and the pixel can be reduced, and image blur due to parallax can be prevented.

Further, the present invention has a plurality of reflecting portions and a propagating portion, and the angle θ1 formed by the principal ray emitted from the light emitting surface of the light guide and the surface normal is 0 ° ≦ θ1 ≦ This is a liquid crystal display device provided with a surface light source that emits light in a direction of 60 °. Thereby, light having directivity can be efficiently emitted, and the viewing angle characteristics in the vertical direction can be further improved.

The present invention is a liquid crystal display device provided with a surface light source in which a plurality of reflecting portions and a propagating portion are repeatedly formed on a surface opposite to an emission surface of a light guiding portion. Thereby, it is possible to give directivity to the light emitted from the surface light source, and it is possible to improve the vertical viewing angle characteristics.

Further, according to the present invention, the second optical means disposed between the surface light source and the liquid crystal display element and / or between the first optical means and the liquid crystal display element, This is a liquid crystal display device in which a principal ray of light emitted in a planar manner from an emission surface is refracted in a direction normal to the emission surface. As a result, the viewing angle characteristics can be improved centering on the surface normal direction (front direction) of the liquid crystal display device.

Further, the present invention is a liquid crystal display device wherein the second optical means comprises a film on which a plurality of prism portions are formed. Thus, inexpensive optical means can be provided.

Further, the present invention is a liquid crystal display device in which a protective layer is formed on a plurality of prism portions formed on the second optical means. Thereby, light leakage of unnecessary light due to scratches on the prism surface can be prevented.

[0039]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described. Embodiments of the liquid crystal display device of the present invention will be described with reference to FIGS.
This will be described with reference to FIG. FIG. 1 is an explanatory longitudinal sectional view schematically showing the structure of the liquid crystal display device of Example 1. FIG.
FIG. 3 is a longitudinal sectional view schematically illustrating the structure of a lens sheet of the liquid crystal display device of Example 1. FIG. 3 is a longitudinal sectional view schematically illustrating the structure of the surface light source of the liquid crystal display device according to the first embodiment. FIG. 4 is a diagram illustrating characteristics in a viewing angle range of the liquid crystal display device according to the first embodiment. FIG. 5 is a diagram illustrating characteristics of the lens of the liquid crystal display device according to the first embodiment at the light receiving angle. FIG. 6 is a longitudinal sectional view schematically illustrating the structure of the liquid crystal display device of Example 2. FIG. 7 is a diagram illustrating an arrangement relationship of a retardation plate with respect to a polarizing plate of the liquid crystal display device according to the second embodiment. FIG. 8 is a longitudinal sectional view schematically showing the structure of the lens sheet of the liquid crystal display device of Example 2. FIG. 9 shows the second embodiment.
It is a longitudinal cross-sectional view which illustrates typically the structure of the surface light source of the liquid crystal display device of FIG. FIG. 10 is a perspective view schematically illustrating the shapes of the propagation portion and the reflection portion of the light guide of the surface light source of the liquid crystal display device according to the second embodiment. FIG. 11 is a diagram illustrating characteristics of the liquid crystal display device according to the second embodiment. FIG. 12 is an explanatory longitudinal sectional view of the liquid crystal display device according to the third embodiment. FIG. 13 is an explanatory diagram of a lens sheet of the liquid crystal display device according to the third embodiment. FIG. 14 is an explanatory longitudinal sectional view schematically showing the structure of the surface light source of the liquid crystal display device according to the third embodiment. FIG. 15 is a perspective view for explaining the shapes of the propagation portion and the reflection portion of the light guide of the surface light source of the liquid crystal display device according to the third embodiment. FIG. 16 is a diagram illustrating characteristics of the liquid crystal display device according to the third embodiment. FIG. 17 is a longitudinal sectional view schematically illustrating the structure of a liquid crystal display device according to a modification of the third embodiment.

(Embodiment 1) The configuration of a liquid crystal display device according to Embodiment 1 of the present invention will be described. As shown in FIG. 1, the transmission type liquid crystal display device according to the first embodiment includes a surface light source 1, a liquid crystal display element 2, and a light diffusion layer 3. The surface light source 1 includes a cold-cathode fluorescent lamp described later and a light guide that uniformly emits incident light from the cold-cathode fluorescent lamp in a planar manner.
The liquid crystal display element 2 includes an active matrix substrate (first substrate) 41 in which thin film transistors (hereinafter, referred to as “TFTs”), transparent electrodes corresponding to pixels, and an alignment film are formed in a matrix on a transparent glass substrate. A color filter substrate (second substrate) 42 on which a transparent electrode, a color filter corresponding to the pixel, and an alignment film are formed, and a twist angle between the first transparent substrate 41 and the second transparent substrate 42. Is almost 90 degrees twisted nematic (hereinafter, referred to as
It is called "TN". A) The liquid crystal layer 5 made of a liquid crystal material is sealed. The liquid crystal layer 5 is made of a liquid crystal material having a positive dielectric anisotropy. The first transparent substrate 41 and the second transparent substrate 42 are sandwiched between a first polarizing plate 61 and a second polarizing plate 62, which form a pair, to form the liquid crystal display element 2. The light diffusion layer 3 is a first optical unit disposed outside the second polarizing plate 62 disposed on the viewer side, and diffuses light emitted from the liquid crystal display element 2.

The transparent electrodes provided on the first transparent substrate 41 and the second transparent substrate 42 are connected to a modulation control means for changing the alignment state of the liquid crystal molecules. The orientation of liquid crystal molecules is controlled by an external electric field, and the light intensity is modulated and controlled.

Next, a method of manufacturing the liquid crystal display device having the above configuration will be described. First transparent substrate 41 and second transparent substrate 42
The first glass substrate 41 is made of 7059 glass (manufactured by Corning Glass Works) having a thickness of 0.7 mm.
Then, an ITO film was formed on the second glass substrate 42 by a sputtering method to form a transparent electrode. Next, as an alignment film,
A polyimide alignment film was formed by a printing method, baked at 180 ° C., and rubbed. The twist angle of the alignment film thus formed is 90 °. Thereafter, in order to keep the distance between the liquid crystal layers 5 constant, a glass fiber spacer of 4.5 μm was sprayed thereon to form a liquid crystal sealing layer of 5.3 μm.
Was formed by screen-printing an adhesive sealing material mixed with the above glass fiber spacer, followed by bonding. Thereafter, liquid crystal was injected between the two substrates by vacuum degassing to form a TN liquid crystal cell. In addition, the first glass substrate 41 and the first glass substrate 42
The polarizing plate 61 and the second polarizing plate 62 are arranged such that their polarization axes (or absorption axes) are orthogonal to each other. At this time, they were arranged such that the polarization axis (or absorption axis) almost coincided with the rubbing direction.

As the liquid crystal display element 2 used in the first embodiment,
Screen size is 15 inches diagonal (vertical: 228.6 mm,
Width: 304.8 mm), the pixels are arranged in stripes, and the number of horizontal pixels is 640 (R, G, B) × the number of vertical pixels is 480;
The pixel pitch is approximately 0.159 mm in the horizontal direction Ph,
A liquid crystal display element 2 having a vertical direction Pv of about 0.476 mm and a black matrix (BM) width of 0.01 mm is used. The color filter substrate (second substrate) 42 has a thickness of 0.7 mm and a refraction. The ratio is 1.52, and the thickness of the second polarizing plate 62 disposed on the viewer side is 0.30.
mm and the refractive index is 1.52. At this time, the air-equivalent distance d from the light diffusion layer 3 to the plane on which the pixels are formed is approximately 0.658 mm.

With respect to the structure of the light diffusion layer 3 in the liquid crystal display device of Example 1, FIG. 2A is a longitudinal sectional view schematically showing the structure of the light diffusion layer 3, and FIG. )
This will be described with reference to FIG. As the light diffusion layer 3, a plurality of lenses 3
A lenticular lens film in which No. 1 was repeatedly formed was used. This lens film 3 is obtained by dropping an ultraviolet curable resin (Z9001, refractive index n = 1.59) manufactured by Nippon Synthetic Rubber Co., Ltd. into a mold in which a concave shape is repeatedly formed. It was arranged, irradiated with ultraviolet rays of 1.0 J / cm ² , and cured to transfer and form the convex portions on the base material 32. At this time, an Arton film manufactured by Nippon Synthetic Rubber Co., Ltd. was used as the base material 32. Note that the method of forming the lens film is not limited to the above, and may be formed by thermal relaxation of a resist film formed on a transparent substrate, or by injection molding using an acrylic resin, or on a glass substrate. It may be formed by an ion exchange method or a glass etching method.

The lens surface formed on the lenticular lens film serving as the diffusion layer 3 is arranged so as to face the second polarizing plate 62 arranged on the viewer side. Also,
The lenticular lens 31 is repeatedly formed so as to be parallel to the vertical pitch Pv of the pixels formed on the liquid crystal display element 2, the pitch P1 is 0.14 mm, the height is 0.04 mm, and the focal length f is It was formed so as to be about 0.14 mm. By forming the lens 31 in this way, the width at which the focal length f intersects on the pixel surface is 0.534 mm.
And The light receiving angle of the lens was ± 30.8 °.

Note that the lens pitch P1 is the pixel pitch P of the liquid crystal display element 2 formed in a direction parallel to the lens.
v less than 1.5 times, more preferably the pixel pitch P
Although it is preferable to form it smaller than v, when the size is smaller than 1/20 times, a rainbow-colored reflected light is observed due to a light diffraction phenomenon on the surface on which the lens is formed, and the display quality is deteriorated. For this reason, it is preferable that the lens pitch P1 is 1/20 or more times the pixel pitch Pv.

In the first embodiment, the light blocking layer 33 is formed on the entire surface of the lenticular killer lens 31. Specifically, an organic material in which a black pigment is dispersed is applied to the surface of the Rentsch killer lens 31 by spin coating, and ultraviolet light is applied for 1.5 times.
The composition was cured by irradiation at J / cm ² . Light shielding layer 3
The film thickness of No. 3 was formed to be approximately 0.005 mm so that the transmittance of the lens film 3 was 70%. Although the screen luminance can be increased as the transmittance of the lens film increases, the decrease in the screen luminance was not noticeable even in the transmittance in Example 1.

The direction of the lens surface is not limited to that of the first embodiment, and the lens surface can be directed to the observer. However, in this case, the air-equivalent distance d between the lens surface and the pixel is separated by the thickness of the base material 32 on which the lens is formed, and the light condensing power of the lens is reduced. Therefore, it is desirable to adjust the distance corresponding to the thickness by the thicknesses of the polarizing plate 62 and the color filter substrate 42.

The arrangement position of the lens film is not limited to that of the first embodiment, but may be arranged inside the polarizing plate 62 of the liquid crystal display element 2. However, in this case, since the air-equivalent distance d from the lens formation surface to the pixel surface is the thickness of the color filter substrate 42, the design of the focal length f of the lens needs to be about 0.46 mm or less. It is desirable that the effect of the birefringence (difference in the refractive index in the molecular direction) by the lens film 3 be reduced as much as possible, and a substrate having almost no birefringence, such as the substrate used in Example 1, is used. preferable. Further, in addition to the above, a lens may be formed on a base material such as PVA (polyvinyl alcohol) having a small birefringence.

The light-shielding layer 33 is not limited to the lens surface.
It may be formed on the surface opposite to the lens surface, or on both the lens surface and the opposite surface. In this case, the reflection of external light entering from the observer side can also be reduced. In addition, in the case of this configuration, considering that the transmittance is reduced by forming the light-shielding layer, particularly when the light-shielding layers are arranged on both sides, the transmittance is controlled by adjusting the formed film thickness. It is desirable.

Next, details of the structure of the surface light source 1 used in the liquid crystal display device of Embodiment 1 will be described with reference to FIG.
The surface light source 1 includes a fluorescent tube 11, a light guide 12, a diffuse reflection sheet 13, and a prism sheet 14. The light guide 12 is formed in a wedge shape with a thickness tin of the incident surface of 4 mm and a thickness tout of a surface facing the incident surface of 2 mm. The surface 122 opposite to the light exit surface 121 of the light guide 12 is subjected to grain printing, and the diffuse reflection sheet 13 is disposed. The light exit surface 121 of the light guide 12 is formed as a prism sheet 14. B made by Sumitomo 3M Co., Ltd.
An EF film was placed. The fluorescent tube 11 was arranged above the display screen.

The viewing angle characteristics of the liquid crystal display device according to the first embodiment will be described with reference to FIG. FIG. 4A shows the relationship between the emission angle and the amount of emitted light of the surface light source 1 used in the first embodiment. FIG. 4B shows the relationship between the contrast in the conventional TN display mode and the viewing angle θ2 (thin solid line), and the relationship between the contrast and the viewing angle θ2 of the liquid crystal display device used in the first embodiment of the present invention (thick solid line). . FIG. 4C shows a conventional TN.
The relationship between the brightness in the display mode and the viewing angle θ2 (thin solid line) and the relationship between the brightness of the liquid crystal display device used in the first embodiment of the present invention and the viewing angle θ2 (thick solid line) are shown.

As is clear from FIG. 4A, the surface light source 1
The principal ray direction θ1 (surface normal direction) of the light emitted from the LCD substantially coincides with the peak direction of the contrast of the liquid crystal display element.

In the above configuration, the light emitted from the surface light source 1 is diffused by the lenticular lens film 3 having a light receiving angle θ1 of ± 30 ° after passing through the liquid crystal display element 2. As a result, the contrast value can be improved to ± 80 ° as compared with the conventional TN liquid crystal display mode in which no lenticular lens film is arranged as shown in FIG.
In addition, compared to the conventional TN liquid crystal display mode in which a lenticular lens film is not disposed, a change in contrast can be reduced, and a display image with a small sense of change can be provided.

Furthermore, as shown in FIG. 4C, the brightness of the liquid crystal display device of the first embodiment is lower than that of the conventional TN liquid crystal display mode in which no lenticular lens film is disposed, although the brightness in the front direction is reduced. In addition, the change rate of the brightness can be reduced, and a display image having no change in the viewing angle can be provided. Note that the measurement results in FIG. 4C are values normalized by the brightness in the 0 ° front direction in both the first embodiment and the conventional TN liquid crystal display mode.

The effect of improving the viewing angle due to the diffusion effect of the lens and the front luminance will be described with reference to FIGS. 5 (a) and 5 (b). As shown in FIG. 5A, the diffusion effect of the lens in this embodiment is such that the light receiving angle θ1 of the lens is ± 3.
When the angle is set to 0 °, the viewing angle range θ2 (indicating an angle range in which a contrast of 10 or more can be ensured) is 175 °, which is an improvement over the conventional TN liquid crystal display mode in which the viewing angle range θ2 is 90 °. The brightness in the front direction (front brightness)
As shown in FIG. 5B, the brightness was reduced to 0.5 times that of the conventional TN display mode, but had no practical problem.

The larger the light receiving angle θ1 of the lens, the stronger the diffusion effect and the wider the viewing angle range, but the lower the brightness in the front direction. When the light receiving angle θ1 is reduced, the effect of improving the viewing angle range is reduced, but the decrease in brightness in the front direction is reduced. As a practical range, the light receiving angle θ1 of the lens is preferably from 5 ° to 40 °.

As described above, according to the liquid crystal display device of the first embodiment, the peak direction of the contrast of the liquid crystal display element substantially coincides with the direction of the principal ray of the light emitted from the surface light source. By providing the first optical means for diffusing the light emitted from the liquid crystal display element on the viewer side of the element, when the light emitted from the surface light source passes through the liquid crystal display element, there is little reduction in contrast and the viewing angle characteristics Can be obtained as a liquid crystal display device in which is improved.

Further, by designing the pitch of the lenses formed on the lens film to be smaller than the pitch of the pixels formed on the liquid crystal display element, it is possible to prevent the occurrence of dark portions and to provide an image with high display quality.

By designing the focal length f of the lens array to be equal to or less than the air-equivalent distance d from the plane on which the lens array is arranged to the pixels formed on the liquid crystal display element, the width x at which the pixels intersect with the focal length f is set. Can diffuse light emitted from a plane of 0.534 mm, and can improve viewing angle characteristics.

Further, the light-blocking means is formed on the entire surface of either the surface on which the lens array is formed or the surface on which the lens is formed, or on both sides, so that the light can reach before reaching the lens. Diffuse reflection of light (stray light) having a shallow angle for total reflection and reflection of external light can be prevented, and the display quality of the liquid crystal display device can be improved. Further, an inexpensive light-shielding layer that can be easily formed can be provided.

In addition, the light source is disposed above the display screen, and a prism film is disposed between the surface light source and the liquid crystal display element, so that the light emitted from the surface light source has directivity. Vertical viewing angle characteristics can be improved.

(Embodiment 2) Hereinafter, the configuration of a liquid crystal display device according to Embodiment 2 of the present invention will be described. The basic configuration of the liquid crystal display device according to the second embodiment is the same as that of the first embodiment, except for the size of the liquid crystal display element, the liquid crystal display mode, the configuration of the surface light source, and the configuration of the lens film. Example 2
As shown in the sectional view of FIG. 6, the liquid crystal display device includes a surface light source 1b, a liquid crystal display element 2b, and a light diffusion layer 3b.

The liquid crystal display element 2b has a first transparent substrate 41b and a second transparent substrate 42b arranged at predetermined intervals. A transparent electrode and an alignment film are provided on the first transparent substrate 41b and the second transparent substrate 42b, respectively. A liquid crystal layer 5b is provided between the first transparent substrate 41b and the second transparent substrate 42b. The liquid crystal layer 5b is made of a liquid crystal material having negative dielectric anisotropy. Modulation control means for changing the alignment form of the liquid crystal molecules is connected to the transparent electrode, which controls the alignment form of the liquid crystal molecules by an electric field which is an external field according to the applied display voltage, and modulates the light intensity. . The first transparent substrate 41b and the second transparent substrate 42
b denotes a pair of a first polarizing plate 61b and a second polarizing plate 62
b, the second transparent substrate 42b and the second polarizer 6
2b, a retardation plate 72 having a positive refractive index anisotropy
Is provided. Thus, a liquid crystal display device as an optical element capable of modulating the intensity of transmitted light is configured.

An example of a method for manufacturing the liquid crystal display element 2b will be described. A 7059 glass substrate (manufactured by Corning Glass Works) having a thickness of 0.7 mm is used as the first transparent substrate 41b and the second transparent substrate 42b.
An O film was formed by a sputtering method to obtain a transparent electrode.

The alignment layer was prepared as follows. That is, after forming an obliquely deposited SiO film, applying a silane coupling agent such as DMOAP and baking at 300 ° C., an orientation slightly inclined from the vertical was realized. In Example 2, the pretilt angle of the alignment film thus formed was 88 ° from the plane of the substrate.

Thereafter, in order to keep the distance between the liquid crystal layers 5 constant, 4.5 μm glass fiber spacers (not shown) were sprayed, and 5.3 μm as a liquid crystal sealing layer (not shown).
An adhesive sealing material mixed with a m glass fiber spacer was formed by screen printing and bonded. Thereafter, a liquid crystal material was injected by vacuum degassing between the two substrates to form a liquid crystal cell.

The liquid crystal display element used in Example 2 has a screen size of 18 inches diagonally (vertical: 274.3 mm, horizontal:
365.7 mm), the pixels are arranged in stripes, and the number of horizontal pixels is 1024 (R, G, B) × the number of vertical pixels 768. The pixel pitch is approximately 0.119 mm in the horizontal direction Ph and approximately 0.357 mm in the vertical direction Pv. A liquid crystal display device was used.
The phase difference plate 72 has a thickness of 0.30 mm, and the refractive index (slow axis) of the larger one of the refractive indices in the substrate surface is represented by n.
Assuming that x is the smaller refractive index and ny is the refractive index in the direction normal to the substrate surface, nx = 1.500
4, ny = 1.5 and nz = 1.50298. Further, as shown in FIG. 7, the first polarizing plate 61b and the second
Are arranged such that their absorption axes are orthogonal to each other and form an angle of 45 ° with the slow axis of the liquid crystal layer 5. The phase axis is arranged to be orthogonal to the slow axis of the liquid crystal layer 5.

The air-equivalent distance d from the light diffusion layer 3b to the plane on which the pixels are formed is 0.857 mm.

Next, details of the structure of the light diffusion layer 3b will be described with reference to the cross-sectional explanatory view of FIG. 8A and the frontal explanatory view of FIG. 8B. Example 2 is the same as Example 1 except that a lenticular lens film is used. However, lenses 31b are formed on both sides of a base material 32b, and the formation direction is perpendicular to the pixels formed on the liquid crystal display element 2. It was repeatedly formed in a direction parallel to the direction pitch Pv. The lens 31b has a pitch P1 of 0.10 mm and a height of 0.01.
5 mm, and the focal length f was 0.15 mm. At this time, the width x at which the pixel formed on the liquid crystal display element and the focal length f intersect is 0.456 mm, and the light receiving angle of the lens is approximately ± 20 °. Further, in Example 2, the light shielding layers 33b were formed on the lens forming surfaces 31b formed on both surfaces of the base material 32b. The light receiving angle θ1 of the lens
Is not limited to the value of Example 2 but is 5 ° to 40 °.
The angle may be in the range of °, which is the same in other embodiments.

Next, the structure of the surface light source 1 used in the second embodiment will be described in detail with reference to FIGS. The surface light source 1b includes two fluorescent tubes 11b and two light guides 12
b, a diffuse reflection sheet 13b.

The light guide 12b used in the second embodiment has an entrance surface 14b and an exit surface as shown in the perspective explanatory view of FIG. 9 and FIG. 10A and the enlarged explanatory view of FIG. 15b and a surface 16b on the opposite side thereof, and a propagation portion 171b and a reflection portion 172b are repeatedly formed on the opposite surface 16b to form a prism portion 17b having a periodic structure. The light guide 12b is manufactured by injection molding using polymethyl methacrylate, and the light incident surface 14b is formed.
The thickness tin of b was set to 2.0 mm, and the thickness tout of the facing surface 18b was set to 1.0 mm.

In the second embodiment, the two light guides 12b are used, and the light incident surfaces 14b are arranged so as to face each other, and the light emitting surfaces 15b are arranged so as to face the observer. The fluorescent tubes 11b are arranged in the vertical direction of the display screen.

The light guide material is not limited to Example 2, but may be acrylic resin such as polymethyl methacrylate, transparent resin such as polycarbonate resin or epoxy resin, glass or the like. It can be manufactured by molding using a processing method such as injection molding, as appropriate.

Next, the propagation section 1 formed on the light guide 12b
Details of 71b and the reflector 172b will be described with reference to FIG. The pitch between the propagating portion 171b and the reflecting portion 172b is 0.16 mm (Pe = 0.01 mm, Pd = 0.
15 mm), and the angle θ2 of the reflecting portion 172b is about 4
Formed at 0 °. By forming the prism portion in this manner, the light source 11 arranged on the incident surface 14b of the light guide 12b
The incident light from b propagates through the light guide 12b while repeating total reflection in the propagation portion 171b of the prism portion 17b formed on the light guide 12b. Here, the light that has entered the reflecting portion 172b is converted into planar light emission from the light guide 12b, and is emitted from the light guide 12b because the condition of total reflection is broken at the emission surface 15b. In the second embodiment, a transparent acrylic resin having a refractive index n of 1.54 is used for the light guide 12b, and the angle θ1 with respect to the normal to the exit surface 15b.
Can emit light having directivity in the direction of ± 15 °. Further, by disposing a diffuse reflection sheet (not shown) on the surface 16b of the light guide 12b opposite to the emission surface 15b, light leaked from the surface 16b of the light guide opposite to the emission surface 15b is provided. Can be reflected to the observer side, and the light use efficiency can be improved. In the second embodiment, the periodic structure formed on the opposing surface of the light guide has a prismatic shape, but may have other irregularities such as a trapezoidal shape, a lenticular shape, and a spherical shape.

The viewing angle characteristics of the liquid crystal display device according to the second embodiment will be described with reference to FIGS. 11 (a), 11 (b) and 11 (c). FIG. 11A is a diagram illustrating the relationship between the emission angle and the amount of emitted light of the surface light source used in the second embodiment. FIG.
1B shows the relationship between the contrast and the viewing angle θ2 (thin solid line) of a conventional liquid crystal display device in a liquid crystal display mode without a lens film, and the contrast of the liquid crystal display device used in Example 2 of the present invention. FIG. 9 is a diagram illustrating a relationship (thick solid line) of a viewing angle θ2. FIG. 11C shows the relationship between the brightness and the viewing angle θ2 (thin solid line) of the conventional liquid crystal display mode without the lens film, and the brightness and the viewing angle θ2 of the liquid crystal display device used in the second embodiment of the present invention. (A thick solid line).

As is clear from FIG. 11 (a), the principal ray direction θ1 (surface normal direction) of the light emitted from the surface light source 1 is
Directivity is shown in the direction of ± 15 °, which is almost coincident with the peak direction of the contrast of the liquid crystal display element.

In the above configuration, the light emitted from the surface light source 1b is diffused by the lenticular lens film 3b having a light receiving angle of ± 20 ° after passing through the liquid crystal display element 2b. As a result, as shown in FIG. 11B, the contrast value can be improved to ± 50 ° in comparison with the conventional liquid crystal display mode in which no lenticular lens film is provided.
Further, compared to the conventional liquid crystal display mode in which no lenticular lens film is provided, the change in contrast can be reduced, and a display image with a small sense of change can be provided.

Further, as shown in FIG. 11 (c), the rate of change in brightness can be made smaller than that in the conventional TN liquid crystal display mode in which no lenticular lens film is provided, and a display image having no change in viewing angle can be provided. . Note that FIG.
The measurement results shown in (c) are values normalized by the brightness in the peak direction of the brightness in both the conventional liquid crystal display mode and the liquid crystal display device of the second embodiment. In the configuration of the second embodiment, the luminance peak (± 15 °) in the conventional liquid crystal display mode is used.
(Brightness in the front direction) can be diffused to the front, thereby improving the brightness in the front direction.

The viewing angle range θ2 of the liquid crystal display device formed as described above could be improved to 80 °, while the viewing angle range of the conventional liquid crystal display mode without the lenticular lens film was 60 °. Further, the brightness in the front direction was improved up to three times as compared with the conventional liquid crystal display mode. However, in the peak direction of the luminance (± 15 ° direction), the luminance was reduced to 0.5 times, but the luminance was practically no problem.

As described above, according to the second embodiment, the transmission having the surface light source, the liquid crystal display element, and the polarizing means disposed on the viewer side or the surface light source side of the liquid crystal display element, respectively. In the liquid crystal display device, the surface light source includes at least one or more light sources and a light guide unit, and the light guide unit includes at least one or more incident surfaces on which light from the light source is incident and an emission surface on which light is emitted. And the liquid crystal display mode used for the liquid crystal display element has two or more peak values of contrast in a direction inclined from the surface normal direction,
By making the direction of the principal ray from the surface light source substantially coincide with the peak value of the contrast, it is possible to provide a liquid crystal display device in which the reduction in contrast is small and the viewing angle characteristics are improved.

The light shielding means is formed on the entire surface of one or both of the surface on which the lens array is formed and the surface opposite to the surface on which the lens is formed, so that the light is totally reflected before reaching the lens. The light (stray light) having a shallow angle can be prevented from being irregularly reflected, and the reflection from the outside light side can be prevented, so that the display quality of the liquid crystal display device can be improved.

Further, since the light-shielding layer is formed on the entire surface of the lens surface or the opposing surface, it is possible to provide an inexpensive light-shielding layer that can be easily formed.

Further, the light source is arranged on one or both of the upper and lower portions of the display screen, so that the direction of the principal ray of the light emitted from the surface light source can be distributed up and down, and the viewing angle in the vertical direction can be increased. Characteristics can be improved.

A plurality of reflection portions and a propagation portion are formed on the surface facing the emission surface of the light guide constituting the surface light source, so that the light emitted from the surface light source has directivity. And the viewing angle characteristics in the vertical direction can be improved.

Further, the plurality of reflecting portions and the propagating portion emit the angle θ1 between the direction of the principal ray emitted from the light emitting surface of the light guide and the surface normal in the range of 0 ° ≦ θ1 ≦ 60 °. By doing so, light with directivity can be efficiently emitted, and the vertical viewing angle characteristics can be further improved.

(Embodiment 3) Hereinafter, Embodiment 3 will be described with reference to FIG.
This will be described with reference to FIGS. The basic configuration of the liquid crystal display device used in the third embodiment is the same as that of the first embodiment.
The configuration of the surface light source and the configuration of the lens film are different. As shown in FIG. 12, the liquid crystal display device according to the third embodiment includes a surface light source 1c, a liquid crystal display element 2c, and a light diffusion layer 3c. The other configuration of the liquid crystal display element 2c used in the third embodiment is the same as that of the first embodiment, and thus the description is omitted.

In Example 3, a lens was formed as the light diffusion layer 3c on the color filter substrate 42c of the liquid crystal display device. For this reason, the air equivalent distance d from the light diffusion layer 3c to the plane on which the pixels are formed is 0.46 mm.

Next, regarding the details of the structure of the light diffusion layer 3c, FIG. 13A is a longitudinal sectional view schematically showing the structure of the light diffusion layer 3c, and FIG. 13B is a front view thereof.
This will be described with reference to FIG. Example 3 was the same as Example 1 except that a lenticular lens was used, but the lens surface was formed on the observer side of the color filter substrate 42c. More specifically, a concave portion is formed on the color filter glass substrate 42c by a glass etching method, and the formed concave portion is made of an ultraviolet-curable resin (T-Case manufactured by Nagase Chiba Co., Ltd.).
714 / R (refractive index n = 1.66) was dropped, and the lens 3c was formed by irradiating ultraviolet rays at 1 J / cm ² .

The formation direction was repeatedly formed in a direction parallel to the vertical pitch Pv of the pixels formed on the liquid crystal display element. At this time, the lens pitch P1 is set to the value in the first embodiment.
However, the focal length f was 0.576 mm because a lens was formed of a UV curable resin having a refractive index of 1.66 on a glass substrate having a refractive index of 1.52. Also,
Since the air-equivalent distance d from the lens forming surface to the plane on which the pixels are formed is 0.46 mm, the width x formed on the pixels corresponding to the pitch width of the lens is 0.028 mm.

In the third embodiment, the second polarizing plate 62c is disposed outside the lens forming surface, and also functions as a light shielding layer.

Next, details of the surface light source used in the third embodiment will be described with reference to FIG. The surface light source 1c includes two fluorescent tubes 11c, a light guide 12c, and a diffuse reflection sheet 13c arranged in a direction corresponding to the vertical direction of the display screen. The thickness of the incident surface 14c is tin
Of 2.0 mm to form a parallel plate structure.

Next, the propagation unit 1 formed on the light guide 12c
Details of 71c and the reflector 172c will be described with reference to FIG. FIG. 15A is a perspective view conceptually showing the shape of the light guide 12c, and FIG. 15B is a partially enlarged perspective view showing the structure of the opposite surface 16c in an enlarged manner. Propagation section 171c and reflection section 172c provided on opposite surface 16c of light guide 12c
Indicates that the pitch Pf of the prism portion 17b is Pf = 0.16 mm (Pe = Pe '= 0.01 m) with respect to the traveling direction of light.
m, Pd = 0.14 mm), and the angle θ4 of the reflection part 172c was formed at about 50 °. By forming the prism portion 17c in this manner, the incident surface 14 of the light guide 12c is formed.
c from the light source 11c disposed on the light guide 12
Then, the light is converted into the planar light emission from the emission surface 15c of the light emitting device c and emitted.

In the surface light source device having the above-described structure, FIG.
As shown in FIG. 6A, it is possible to emit light having directivity in the normal direction of the emission surface 15c.

The emission characteristics and viewing angle characteristics of the liquid crystal display device having the configuration of the surface light source, the liquid crystal display element, and the lens film of the third embodiment are shown in FIGS.
This will be described with reference to FIG. FIG. 16A is a diagram illustrating the relationship between the emission angle and the amount of emitted light of the surface light source used in the third embodiment. FIG. 16B shows the relationship between the contrast in the conventional TN display mode and the viewing angle θ2 (thin solid line), and the contrast and the viewing angle θ2 of the liquid crystal display device used in the third embodiment of the present invention.
(A thick solid line). FIG. 16 (c)
Is the relationship between the brightness of the conventional TN display mode and the viewing angle θ2.
FIG. 10 is a diagram (thin solid line) and a relationship between the brightness of the liquid crystal display device used in the third embodiment of the present invention and the viewing angle θ2 (thick solid line).

While the conventional TN liquid crystal display mode liquid crystal display device without a lenticular lens film has a viewing angle range of approximately 90 °, as shown in FIG. The viewing angle range was 130 °, and the viewing angle dependency was improved. The degree of change in contrast corresponding to the change in viewing angle θ2 is shown in FIG.
As shown in (1), it is possible to provide a liquid crystal display device which is smaller than the degree of change in contrast in the conventional TN liquid crystal display mode in which no lenticular lens film is disposed, and has a small sense of change in contrast. Further, as shown in FIG. 16C, in the liquid crystal display device of Example 3, the change in brightness at the viewing angle θ2 with respect to the brightness in the front direction is changed to the conventional TN liquid crystal display mode in which no lenticular lens film is disposed. Compared with this, it is possible to provide a display image that can be made smaller and has no change in viewing angle. At this time, the brightness in the front direction was 0.9 times that of the conventional TN display mode, and there was almost no change.

In Example 3, the lens has a focal length f of 0.576 mm and a pitch P1 of 0.14 mm, and the light receiving angle θ1 of the lens is ± 7 °. As shown, even when the incident angle θ1 is 10 °, the emitted light can be diffused to a direction of approximately 30 °.

The viewing angle range of the liquid crystal display device of the third embodiment is the same as that of the second embodiment. The viewing angle in the vertical direction is different from the viewing angle characteristic of the TN display mode in which the conventional TN liquid crystal is twisted and arranged at 90 °. Can be provided.

Although the lenticular lens formed on the color filter substrate 42c was used as the light diffusion layer in the third embodiment, a light scattering layer containing scattering particles in the color filter may be used. The configuration of this modified example will be described with reference to FIG. FIG. 17 shows the third embodiment.
It is a longitudinal cross-sectional view which shows typically the structure of the transmission type liquid crystal display device which is a modification of. This liquid crystal display device has the same basic configuration as that of the third embodiment.
d. The liquid crystal display device 2d includes a light diffusion layer (color filter layer) 3d, a first transparent substrate 41d, a second transparent substrate 42d, a liquid crystal layer 5d, a first polarizing plate 61d, and a second polarizing plate 62d. I have. In this modification, a light diffusion layer 3d in which scattering particles are dispersed in a color filter layer was used. More specifically, glass beads having a particle size of 3 μm are dispersed in a color filter material containing a dye (R, G, or B) in PVA (polyvinyl alcohol), and the observer side of the liquid crystal display element is spin-coated. After coating on the substrate 42d, etching was performed to form a color filter in a stripe shape.

In the modification of the third embodiment, the distance from the light diffusion layer 3d to the pixel can be set to 4.5 μm, and unnecessary irregular reflection of light can be prevented. As a result, a liquid crystal display device without pixel blur can be provided. The light emitted from the surface light source 1d is
It is scattered by the scattering particles, and the viewing angle range can be widened.

Also in Embodiment 3 and its modifications, the arrangement distance between the pixel and the light diffusion layer can be made as short as possible, so that image blur due to parallax can be prevented.

As described above, according to the third embodiment and its modification, the light diffusion is formed on the observer-side substrate of the liquid crystal display element, so that the light diffusion from the surface on which the lens is disposed to the pixel is achieved. The distance can be shortened, and image blur due to parallax can be prevented. Further, since the focal length of the lens itself can be designed to be short, a lens having a high light-collecting power can be provided, and a bright liquid crystal display device can be provided.

Further, the lens array is formed by filling a plurality of uneven surfaces formed on the glass substrate with a resin having a refractive index different from that of the glass substrate, so that the lens substrate can be flattened. .

Since the optical element is formed of an organic material containing scattering particles between the observer-side substrate and the color filter, the distance between the scattering surface and the pixel can be shortened, and the image blur due to parallax is reduced. Can be prevented.

[0105]

As described above, according to the present invention,
By improving the viewing angle characteristics, a liquid crystal display device using a transmission type liquid crystal display element having excellent display quality can be obtained.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view schematically showing the structure of a liquid crystal display device according to a first embodiment.

FIG. 2 is a longitudinal sectional view schematically showing a structure of a lens sheet of the liquid crystal display device of Example 1.

FIG. 3 is a longitudinal sectional view schematically showing a structure of a surface light source of the liquid crystal display device according to the first embodiment.

FIG. 4 is a diagram illustrating characteristics in a viewing angle range of the liquid crystal display device according to the first embodiment.

FIG. 5 is a diagram illustrating characteristics of a lens of the liquid crystal display device according to the first embodiment at a light receiving angle.

FIG. 6 is a longitudinal sectional view schematically illustrating the structure of a liquid crystal display device according to a second embodiment.

FIG. 7 is a view for explaining an arrangement of a retardation plate with respect to a polarizing plate of the liquid crystal display device of Example 2.

FIG. 8 is a longitudinal sectional view schematically showing a structure of a lens sheet of the liquid crystal display device of Example 2.

FIG. 9 is a longitudinal sectional view schematically showing a structure of a surface light source of the liquid crystal display device according to the second embodiment.

FIG. 10 is a perspective view schematically showing a structure of a transmission unit and a reflection unit of a surface light source of the liquid crystal display device according to the second embodiment.

FIG. 11 illustrates characteristics of the liquid crystal display device of Example 2.

FIG. 12 is a longitudinal sectional view schematically illustrating the structure of a liquid crystal display device according to a third embodiment.

FIG. 13 is a longitudinal sectional view schematically showing a structure of a lens sheet of the liquid crystal display device of Example 3.

FIG. 14 is a longitudinal sectional view schematically showing a structure of a surface light source of a liquid crystal display device according to a third embodiment.

FIG. 15 is a longitudinal sectional view schematically showing a structure of a propagation unit and a reflection unit of a surface light source of the liquid crystal display device according to the third embodiment.

FIG. 16 is a diagram illustrating characteristics of the liquid crystal display device according to the third embodiment.

FIG. 17 is a longitudinal sectional view schematically showing the structure of a liquid crystal display device according to a modification of the third embodiment.

FIG. 18 is a diagram illustrating an arrangement pattern of a color filter.

FIG. 19 is a diagram illustrating a pixel pitch Pv in a liquid crystal display device.

FIG. 20 shows a pixel pitch Pv and a width x in a liquid crystal display device.
FIG.

FIG. 21 is a view for explaining a method for measuring the relationship between the measurement angle and the relative brightness and the measurement result in the first embodiment.

FIG. 22 is a view for explaining a method for measuring the relationship between the diffusion angle and the relative brightness and the measurement result in the first embodiment.

FIG. 23 is a view for explaining a method of measuring changes in viewing angle characteristics and brightness when the light receiving angle θ1 of the lens in Example 1 is changed.

FIG. 24 is a perspective view schematically showing the structure of a liquid crystal display device of Conventional Example 1.

FIG. 25 is a longitudinal sectional view schematically showing the structure of a liquid crystal display device of Conventional Example 2.

FIG. 26 is a longitudinal sectional view schematically showing the structure of a liquid crystal display device of Conventional Example 3.

[Explanation of symbols]

1 surface light source, 11 fluorescent tube, 12 light guide, 12
Reference Signs List 1 outgoing surface, 13 diffuse reflection sheet, 14 prism sheet, 2 liquid crystal display element, 3 light diffusion layer, 31 lens, 32 base material, 33 light shielding layer, 41, 42 substrate, 5 liquid crystal layer, 61, 62 polarizing plate,

Claims (14)

[Claims] 1. A liquid crystal display device comprising a pair of glass substrates facing each other with a transparent electrode on an inner surface side and having a liquid crystal material injected therebetween, and having a plurality of pixels formed thereon, and an observer of the liquid crystal display device. In a liquid crystal display device comprising a pair of polarizing means and a surface light source disposed on the side and the surface light source side, respectively, the peak direction of the contrast of the liquid crystal display element is in a direction at a predetermined angle from the surface normal direction. A liquid crystal, comprising: a first optical means for diffusing the light emitted from the liquid crystal display element on the observer side of the liquid crystal display element, wherein the first optical means substantially coincides with the principal ray direction of the light emitted from the surface light source. Display device. 2. The surface light source includes one or more light source units and a light guide unit, and the light guide unit emits at least one light incident surface on which light from the light source unit is incident. And a peak direction of contrast of the liquid crystal display element is at two predetermined angles from a surface normal direction and substantially coincides with a principal ray direction of light emitted from the surface light source. Item 2. The liquid crystal display device according to item 1. 3. The first optical means comprises a plurality of lens arrays formed parallel or perpendicular to the pixels formed on the liquid crystal display element, wherein the pitch of the lens arrays is P1, The liquid crystal display element formed in a direction parallel to the array pitch P1 direction, wherein the pixel pitch is P2, wherein the pixel pitch is formed so as to satisfy (1/20) × P2 ≦ P1 <P2. 3. The liquid crystal display device according to 2. 4. The pitch of the lens array is P1, the focal length is f, the distance in air from the plane on which the lens array is arranged to the pixels formed on the liquid crystal display element is d, and the pixel pitch is P2. When the width of the black matrix formed in the pitch P2 direction is P3, the width x formed on the pixel corresponding to the pitch width of the lens array around the focal length is: x = P1 × | (d− f) | / f (| (df) | indicates an absolute value), and satisfies the range of 0 ≦ x ≦ (1.5 × P2). Liquid crystal display. 5. The width x is more preferably P3 ≦ x
The liquid crystal display device according to claim 4, wherein ≤P2. 6. The liquid crystal display device according to claim 1, wherein the lens array satisfies 5 ° ≦ θ1 ≦ 40 ° when the light receiving angle is θ1. 7. A light-shielding means is formed on the entire surface of one or both of the surface on which the lens array is formed and the surface opposite to the surface on which the lens array is formed. The liquid crystal display device according to claim 6. 8. The liquid crystal display device according to claim 3, wherein the lens array is formed on an observer's side surface of a substrate arranged to face the liquid crystal display element. 9. An organic material having a first optical element formed on a viewer side of a substrate opposed to the liquid crystal display element and containing scattering particles between the substrate and a color filter. The liquid crystal display device according to any one of claims 3 to 8, wherein the liquid crystal display device is formed by: 10. An optical system comprising a plurality of reflecting portions and a propagating portion, wherein an angle θ1 formed by a principal ray emitted from an emitting surface of the light guiding portion and a surface normal is set in a direction of 0 ° ≦ θ1 ≦ 60 °. The liquid crystal display device according to claim 1, further comprising a surface light source that emits light. 11. The liquid crystal display device according to claim 10, further comprising a surface light source in which a plurality of reflection portions and a propagation portion are repeatedly formed on a surface of the light guide portion facing the emission surface. 12. A liquid crystal display device comprising: a surface light source and a liquid crystal display element;
One of the optical means and the liquid crystal display element,
12. The liquid crystal display according to claim 10, wherein a principal ray of light emitted in a plane from the exit surface is refracted in a direction normal to the exit surface by the second optical means disposed on both sides. apparatus. 13. The liquid crystal display device according to claim 12, wherein the second optical means comprises a film on which a plurality of prism portions are formed. 14. The liquid crystal display device according to claim 13, wherein a protective layer is formed on the plurality of prism portions formed on the second optical unit.