JPH0895018A - Display device - Google Patents

Abstract

PURPOSE: To enlarge a visual angle and easily look at a display by providing a visual angle control means with a plural of small through-holes on the surface of a display panel. CONSTITUTION: A visual angle control sheet 40 formed with a black resin film is provided on the upper face of an upward polarizing plate 26. The visual angle control sheet 40 has cylindrical through-holes 42 formed at given spaces. The visual angle control sheet 40, the surface of which is smoothed by a black rubber sheet for surface treatment, has a reflectance of 1% or less to outer light. In a relationship between the size of the through-hole 42 and the size of a display picture element, if the size of one display picture element is 100μm×100μm, the through-holes 42 of diameter 2μm are made at 2μm spaces or so to ensure sufficient display brightness. When the visual angle control sheet 40 which has a number of such through-holes arranged is pasted to the polarizing plate 26, light entered through a liquid crystal display device 10 into the through-holes 42 causes strong diffraction at the exits so that people greatly enlarges their visual angle when looking at diffracted light.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device composed of a plurality of display picture elements.

[0002]

2. Description of the Related Art In recent years, the field of use of display devices, particularly liquid crystal display devices, has expanded, and they have come to be used in office computers, aircraft information terminals, in-vehicle televisions, etc., and one liquid crystal display device can be used at various angles. From the beginning, or the use by multiple people is increasing. Therefore, it has been required that the viewing angle of the liquid crystal display device be enlarged so that the image can be clearly seen from any direction.

By the way, the structure of the conventional liquid crystal display device 300 is as shown in FIG.
14, the color filter 316, the counter electrode 318,
A display element 324 including an alignment film 320, a liquid crystal layer 322, a pixel electrode, a thin film transistor, and various wirings is provided. Polarizing plates 326 and 328 are provided on the upper surface of the glass substrate 312 and the lower surface of the glass substrate 314, respectively. Further, below the polarizing plate 328, a diffusion plate 330, a backlight 332, and a reflection plate 334 are provided. As shown in FIG. 10, the color filter 31
6, a black matrix 336 is provided in a lattice shape to increase the contrast.

In the liquid crystal display device 300 as described above, since the viewing angle is narrow due to the characteristics of the liquid crystal, it is necessary to enlarge the viewing angle. Therefore, as shown in FIG. 11, between the polarizing plate 326 and the glass substrate 312, there is disclosed in JP-A-60-135902.
It is known to provide a directional filter 338 as disclosed in U.S. Pat.

The directional filter 338 controls the phase difference and the refractive index of the light passing through the liquid crystal display device 300, thereby expanding the viewing angle.

[0006]

However, the directional filter 338 as described above has a problem in terms of cost.

There is also a dual domain method in which the viewing angle is expanded by changing the alignment direction of the liquid crystal in the display pixel in display pixel units, but this method cannot obtain a sufficient expansion of the viewing angle. Furthermore, since it is necessary to perform the orientation treatment in various directions, the number of steps is increased, and the manufacturing yield has not been sufficiently improved.

In view of the above problems, the present invention provides a display device capable of enlarging the viewing angle of a liquid crystal display device and keeping the cost low.

[0009]

A display device of the present invention comprises a display panel in which a plurality of display picture elements are regularly arranged in a plane, and a large number of through holes smaller than the one display picture element. And a visual angle control means.

[0010]

[Operation] According to the display device of the present invention, a viewing angle control in which a plurality of through holes smaller than the one display pixel are formed in a display panel in which a plurality of display pixels are regularly arranged on a plane. Because of the provision of means, this small through-hole
Diffraction of light occurs and the viewing angle can be expanded.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The structure of a liquid crystal display device 10 according to a first embodiment of the present invention will be described below with reference to FIGS.

Reference numeral 12 is a glass substrate, and a color filter 16, a counter electrode 18 and an alignment film 20 are provided on the lower main surface in FIG. The color filters 16 are R,
Each of the G and B color portions is arranged in a grid pattern. Then, the glass substrate 12, the color filter 16, the counter electrode 18, and the alignment film 20 form a counter substrate 21.

Reference numeral 24 is provided on the upper surface of another glass substrate 14.

Pixel electrodes installed via a plurality of signal lines, scanning lines, and thin film transistors arranged in the vicinity of the intersections of the signal lines and the scanning lines are shown in a simplified manner.

Reference numeral 22 is a liquid crystal layer, which is a counter substrate 21.
And the array substrate 25.

Reference numeral 26 is a display-side polarizing plate provided on the upper surface of the glass substrate 12.

Reference numeral 28 is a backlight side polarizing plate provided on the lower surface of the glass substrate 14. A diffusion plate 30, a backlight 32, and a reflection plate 34 are provided below the polarizing plate 28 in order to make the light from the backlight 30 uniform.

Reference numeral 40 is a viewing angle control sheet made of a black resin film provided on the upper surface of the upper polarizing plate 26. As shown in FIGS. 2 and 3, the viewing angle control sheet 40 is provided with cylindrical through holes 42 at regular intervals. The surface of the viewing angle control sheet 40 is roughened with a black rubber sheet to be surface-treated, and the reflectance with respect to external light is 1% or less. The relationship between the size of the through-hole 42 and the display pixel is, for example, when one display pixel has a size of 100 μm × 100 μm, the through-hole 42 having a diameter of 2 μm is formed at an interval of about 2 μm. Sufficient display brightness can be secured.

In this embodiment, the through holes 42 having a diameter of 2 μm are arranged at intervals of 2 μm. However, depending on the size of the display pixel, the distance between the through holes 42 having a diameter of about 10 to 20 μm is sufficient. There is no need to consider alignment accuracy.
Further, in consideration of the light use efficiency, it is preferable that the interval between the through holes 42 is narrow, and if it is 10 μm or less, for example, about 5 μm, sufficient use efficiency can be obtained.

With the liquid crystal display device 10 as described above,
Since the degree of diffraction of the light coming from the polarizing plate 26 increases in inverse proportion to the diameter of the through-hole 42, the transmitted light of the through-hole 42 can be transmitted not only in the direction perpendicular to the opening surface of the through-hole 42 but also in the oblique direction. Can be observed. And a very small through hole 4
2, for example, a through hole 42 having a diameter of several microns or less
Light that has passed through can be observed from any position on the observation side hemisphere of the sphere centered on the aperture plane. Therefore, when the viewing angle control sheet 40 in which a large number of such through holes 42 are arranged is attached to the polarizing plate 26, the light that has passed through the liquid crystal display device 10 enters the through holes 42 and causes strong diffraction at the exits thereof. Since this diffracted light is seen, the viewing angle can be greatly expanded.

The position where the through-hole 42 is provided is
Since the size and shape of the display pixel of the liquid crystal display device 10 are irrelevant, by arranging a large number of small through holes 42, there is no influence on the attachment accuracy of the viewing angle control sheet 40 to the polarizing plate 26.

Further, since the black surface of the viewing angle control sheet 40 is roughened, surface reflection can be reduced. Then, by using the black material as the viewing angle control sheet 40, it is possible to obtain the maximum contrast as compared with the case where the viewing angle control sheet 40 is made of a material of another color. Therefore, it is not necessary to provide a black matrix as in the conventional case.

Further, since the through-hole 42 has an extremely small area with respect to the display pixel, a partial defect mode in the pixel, for example, small dust, a pinhole of the counter electrode, a partial liquid crystal alignment. A single pixel, such as an anomaly, has significant redundancy for all unaffected defects. Further, it is possible to make inconspicuous macroscopic defective modes such as spots and stains on the screen, which are conventionally caused, so that the yield is improved.

In order to improve the display brightness, it is possible to increase the brightness by narrowing the interval instead of increasing the diameter of the through hole. Further, if the relationship between the sheet thickness and the diameter of the through hole is set to about 16: 1, the reflectance of the incident light on the inner wall surface of the through hole can be effectively taken out, and the maximum brightness can be obtained.

By forming the through-hole 42 into a polygonal shape or another closed curved surface instead of the circular shape in plan view, it is possible to provide the directivity of the viewing angle for improving the specific viewing angle.

As a method of providing the through-hole 42 in the view angle control sheet 40, it is formed by using a lithography technique. The viewing angle control sheet 40 is made of black plastic,
Examples include polyimide, other resins, and metals. Also,
A non-black film coated with silver borate may be oxidized. That is, the material condition may be any as long as the through hole can be accurately etched by lithography. Then, surface treatment is applied to reduce the surface reflection.

The liquid crystal display device 10 described above is capable of widening the viewing angle, has almost no surface reflection, is inexpensive, and can be manufactured with a few steps.

The liquid crystal display device 100 of the second embodiment will be described with reference to FIG.

The difference between this embodiment and the first embodiment is that each of the through-holes 42 of the viewing angle control sheet 40 is filled with a colored translucent resin. Normally, three colors of red (R), green (G), and blue (B) are required for the filter, so that each through-hole 42 has a colored semi-transparent color having one of R, G, and B. It is filled with resin.

The method of filling the colored translucent resin is as follows.

First, filling is performed by a method such as dropping, coating, and immersing in resin.

Then, pressure is applied for a short time from one surface of the viewing angle control sheet 40 filled with the colored translucent resin.

As a result, when the resin 44 protruding from the other surface becomes spherical due to surface tension, the resin is cured.

Further, the head may be made to pop out from the surface of the viewing angle control sheet 40 by using the centrifugal force or air pressure. Hereinafter, the colored translucent resin that is projected and cured from the surface of the viewing angle control sheet 40 will be referred to as microbeads 44.

The micro beads 44 are used for the liquid crystal display device 10.
At least one pixel is provided on each pixel of 0, but the pixel interval and the interval of the light transmission amount of the micro beads 44 may be taken into consideration.

The viewing angle control sheet 40 is the deflection plate 2
Since it is provided on the surface of 6, the light incident on the viewing angle control sheet 40 itself must form an image, and the microbeads 44 scatter the light, but It has no effect on the switching function for light or the turning property of light. At this time, the amount of light (transmittance) passing through the viewing angle control sheet 40 is determined by the size of the microbeads 44 on the pixel and the number of pixels on the pixel. The larger the microbeads 44, the higher the transmittance. Therefore, a clear image can be obtained. However, when the diameter of the microbeads 44 is reduced and a large number of microbeads 44 are arranged, the viewing angle control sheet 40 is arranged on the orientation plate 26.
It is possible to give redundancy to the alignment accuracy when bonding to.

Since the liquid crystal display device 100 has an effect of projecting and scattering light on the micro beads 44, the viewing angle can be improved.

Further, since the micro beads 44 are colored in three colors respectively, the color filter conventionally required is not necessary. Therefore, it is only necessary to directly provide the counter electrode 18 and the orientation plate 20 on the glass substrate 12.

Further, as in the first embodiment, by treating the surface of the viewing angle control sheet 40, the surface reflection can be reduced. Since the viewing angle control sheet 40 is black, it is possible to eliminate the black matrix.

Note that the viewing angle control sheet 40 may be attached at a position above the deflection plate 26, and a transparent glass substrate or the like may be interposed between the deflection plate 26 and the viewing angle control sheet 40. However, it is preferable that the viewing angle control sheet 40 be in close contact with the deflection plate 26 for the brightness and clarity of the display.

Next, the liquid crystal display device 200 of the third embodiment.
Will be described with reference to FIG.

The difference between this embodiment and the second embodiment is that
In the case of this embodiment, the microbeads 44 are formed of a colorless transparent resin and have the color filter 16.

Also in the liquid crystal display device 200, since the light passing through the microbeads 44 has the effect of being expanded and refracted and spread, the viewing angle can be improved. Further, since the viewing angle control sheet 40 is black, the contrast can be improved, and it is not necessary to provide a black matrix as in the conventional case. Therefore, the attachment accuracy of the filter may be low.

In the second and third embodiments, when the through hole 42 is filled with resin to form the microbeads 44, as shown in FIG. 6, the upper half of the through hole 42 is filled. Alternatively, as shown in FIG. 7, it may be filled over substantially the entire length of the through-hole 42, or as shown in FIG. 8, only the surface of the through-hole 42 may be filled.

Although the viewing angle control sheet 40 is provided on the upper surface of the deflection plate 26 on the display side in the above three embodiments, it may be provided on the lower surface of the deflection plate 28 on the backlight side instead of this. Thereby, the light from the backlight 32 is diffracted by the through-hole 42, and the display state of the liquid crystal can be improved.

[0046]

According to the display device of the present invention, by providing the viewing angle control means having a plurality of small through-holes formed on the surface of the display panel, the viewing angle can be enlarged and the display can be made easy to see. .

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is a plan view of a viewing angle control sheet used in the previous figure.

FIG. 3 is an enlarged vertical sectional view of the view angle control sheet of the previous figure.

FIG. 4 is a vertical sectional view of a liquid crystal display device according to a second embodiment.

FIG. 5 is a vertical sectional view of a liquid crystal display device according to a third embodiment.

FIG. 6 is an enlarged vertical sectional view of a through-hole in each of the embodiments.

FIG. 7 is an enlarged vertical sectional view of a modified example of a through hole.

FIG. 8 is an enlarged vertical sectional view of another modification of the through hole.

FIG. 9 is a vertical cross-sectional view of a conventional liquid crystal display device.

FIG. 10 is a plan view showing a color filter and a black matrix in the previous figure.

FIG. 11 is a vertical cross-sectional view of a conventional liquid crystal display device provided with a compensating plate.

[Explanation of symbols]

 10 Glass Substrate 14 Glass Substrate 16 Color Filter 18 Counter Electrode 20 Alignment Film 22 Liquid Crystal Layer 24 TFT Substrate 26 Deflection Plate 28 Deflection Plate 30 Diffuser Plate 32 Backlight 34 Reflector 40 Viewing Angle Control Sheet 42 Through Hole 44 Micro Beads

Claims (7)

[Claims] 1. A display panel comprising a plurality of display picture elements arranged regularly in a plane, and a viewing angle control means having a large number of through holes smaller than the one display picture element. Display device. 2. The display device according to claim 1, wherein the sheet-shaped viewing angle control means is provided on an incident light surface or an emission light surface of the display picture element. 3. The display device according to claim 1, wherein the viewing angle control means is provided on the viewing side of the display panel. 4. The display device according to claim 1, wherein the viewing angle control means is a resin film. 5. The display device according to claim 1, wherein at least 30 or more through holes are formed for each display picture element. 6. The display device according to claim 1, wherein the through-hole is closed with a transparent resin material to impart a lens function to the through-hole. 7. The display device according to claim 6, wherein the resin material selectively controls the wavelength of transmitted light.