JPS6395489A - Liquid crystal display with filter - Google Patents

Abstract

(57) [Abstract] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid crystal display with reduced viewing angle dependence.

[Conventional technology]

The use of liquid crystal displays as display devices that can be driven with low power consumption is expanding more and more, and in recent years, expectations have increased for them as an alternative to CR displays and color TV picture tubes, and many research results have been published. Currently, most liquid crystal displays use twisted nematic liquid crystals because of their fast response speed and high contrast ratio. FIG. 7 shows an example of the display principle of a transmission type twisted nematic liquid crystal display. A transmissive liquid crystal display has the smallest unit (hereinafter referred to as a pixel) that has the function of controlling light transmission depending on the ON/OFF state.
Consisted of. A pixel consists of a transparent electrode 704 provided on two substrates 702 between two polarizing plates 703 facing each other in a direction such that the polarization axes are parallel to each other, and a twisted nematic liquid crystal 705 arranged in a twisted manner. provided and configured. In the ON state, as shown in FIG. 7(a), a potential is applied to the transparent electrophoresis 704, causing the liquid crystal 705 to stand up, allowing light from the light source 700 to pass therethrough. However, in the OF F' state, the liquid crystal 705 is between the two transparent electrodes 704 as shown in FIG.
The light source 7 follows the twisted liquid crystal molecules.
Since the polarization axis of the light from 00 is rotated by 90 degrees, it cannot pass through the other polarizing plate. A liquid crystal display constructs an image by combining a large number of pixels and controlling each point with 0NIJFF.

[Problem that the invention seeks to solve]

The conventional liquid crystal display described above uses a polarizing plate 703 to control light transmission. However, a polarizing plate has a property that it cannot polarize light that is obliquely incident on the polarizing plane, and as shown in FIG.
The liquid crystal display 811 transmits light even when the pixel 806 is in the OFF state, and therefore, the liquid crystal display 811 has a drawback that the image quality, particularly the contrast, changes depending on the viewing angle of the viewing plane, which is highly dependent on the viewing angle.

Therefore, when viewed from an angle other than perpendicular to the viewing plane, the amount of transmitted light differs from the normal control amount, resulting in a problem of deteriorating image quality.

[Means for solving problems]

The above-mentioned conventional liquid crystal displays do not have a lining to prevent light from being transmitted in an oblique direction, which causes a reduction in image quality (contrast) when viewed from an angle other than perpendicular to the viewing plane. In contrast, the present invention has a filter on the viewing surface of the liquid crystal display, and the inner wall surface of the filter or the hole itself is made of a material that has high absorption in the visible light range. The hole has a light scattering surface 2 perpendicular to the viewing surface of the liquid crystal display, and has a light scattering surface 2 on the opposite side of the surface in contact with the viewing surface of the liquid crystal display, and the thickness thereof is 0.7 or more of the longest plane length of the hole. By providing a filter in contact with the viewing surface of the liquid crystal display, it absorbs the light transmitted in the diagonal direction and scatters the light transmitted vertically, so that the same image quality can be viewed from any direction. This is what I did.

〔Example〕

Next, the pressure of the present invention will be explained with reference to the drawings.

FIG. 1 is a schematic conceptual diagram showing the structure of a liquid crystal display with a filter according to an embodiment of the present invention. Transparent electrode 1
Twisted nematic liquid crystal 105 is filled between two electrode substrates 102 provided with 04, and polarizing plates 103 are provided on both sides. A light source 100 is provided on the side of one polarizing plate 103, and the other polarizing plate 103 serves as a viewing surface 114 of a liquid crystal display. This field of view 114
A filter 101 for improving viewing angle dependence is provided adjacent to the lens.

Next, the detailed structure of the filter 101 for improving viewing angle dependence will be explained with reference to FIG.

FIG. 2 is a schematic partially enlarged perspective view of a liquid crystal display A with a filter.A polarizing plate 2 provided on two electrode substrates 202 is shown in FIG.
03 are arranged in parallel so that their polarization axes face in the same direction.

The transparent electrodes 204 are arranged inside the polarizing plate 203.
They are molded to face each other with a size of r+rr+xbmm. Twisted nematic liquid crystal 205
is sealed between the polarizing plates 203, and by rubbing the crystal axis is set at 90° between the polarizing plate surface on the viewing surface side and the polarizing plate surface on the opposite side.
The directions are different, and the polarization axis and the crystal axis are oriented in the INJ direction on the polarizing plate surface opposite to the viewing surface.

When an electric field is applied to the transparent electrode 204, the molecules of the twisted liquid crystal 205 stand up and transmit light. It is thought that the transparent part is approximately equal to the size of the transparent electrode 204,
There are 206 pixels of size amm x bmm on the viewing plane. In this implementation row, a filter 201 with holes corresponding one-to-one to the pixels 206 is provided in contact with the viewing surface of the liquid crystal display (in the figure, the surface of the upper polarizing plate 2030) (in the figure, for illustrative purposes, the filter and the viewing surface are (Listed separately.) The filter 201 is composed of a frame 207 and a scattering surface 209. Frame 207 is
A black ABS resin is molded into a plate shape having a thickness of hmm and has a vertical hole having an aperture diameter of amm x bmm C1 corresponding to each pixel 206 on a one-to-one basis. Here a
= b = 0.5 (mm), h = 1 (mm) and hole 1
The hole size was set to be 0.7 or more. The scattering surface 209 provided on the surface 215 has transparent resin 208 in seven rooms 207.
The surface is finished with a scattering surface after being filled with. Transparent resin 2
08 only needs to fill at least the scattering surface 209.
07 does not have to be filled in the entire depth direction. It was,
The scattering surface 209 does not have to be a flat scattering surface. Also, the shape of the hole does not have to be square.

In this embodiment, the thickness of the filter 201 is determined by the long side of each hole (
In the case of a circle, the diameter is set to 0.7 or more, so it absorbs the light that passes through the liquid crystal display in an oblique direction, and scatters only the light that passes almost vertically on the scattering surface, so that it looks the same from any direction. It can be seen in

Further, in this embodiment, since the holes correspond to the pixels 206 on a one-to-one basis, there is an advantage that the resolution does not deteriorate.

FIG. 3 is a partial plan view showing another embodiment of the present invention. In this embodiment, similarly to the embodiment shown in FIGS. , Toru #
It consists of Jt pole 304 and twisted nematic 305 liquid crystal. Filter portion 318 is part of frame 30
7, a scattering surface 309, and an absorption/#310. The material of the frame 307 does not necessarily have to be black resin, but may be other resins or gold. Absorbent layer 31
0 is a hole surrounded by a frame 307, and the inner wall thereof is covered with a substance such as black paint that has high absorption in the visible light range.

Transparent resin 3 filled in scattering surface 309Vi frame 307
The surface of 08 is finished as a scattering surface, but it does not have to be flat. Alternatively, the scattering surface 309 may be provided in the form of a film, and the holes 319 may remain hollow.

In this embodiment, since the number of holes is larger than the number of pixels, several holes 319t are provided on the transparent electrode 304 corresponding to one pixel. For this purpose, even if the thickness of the filter part 318 is made thin, the absorption layer 310 absorbs the light that is transmitted obliquely, and the scattering surface scatters only the light that is transmitted almost perpendicularly, so that it is the same from any direction. You can see it like this. Further, in this embodiment, the leftover end can be used as the frame material, so there is an advantage that the strength can be increased. [Effects of the Invention] Next, the present invention will be explained in detail. As shown in Fig. 4, the filter has all the holes perpendicular to the polarizing plate 403 (upper side) on the viewing plane, and the inner wall layer is made of a material that has high absorption in the visible light range and is made of a frame 40.
It is formed by 7. By providing such a filter in contact with the viewing surface of the full liquid crystal display (on the upper polarizing plate 403), it is possible to absorb light from the light source 100 that passes through the polarizing plate 403 obliquely. Furthermore, by providing a scattering surface 409 on the surface opposite to the surface in contact with the viewing surface of the filter, light that is selectively transmitted through the holes of the filter and received at an angle perpendicular to or close to the polarizing plate on the viewing surface is can be scattered.

For example, the size of the light angle selected here can be determined by the thickness of the filter and the size of the hole diameter. Fifth
In the case where the hole is circular in the figure, maximum transmission angle θmax with respect to hole diameter (diameter)/filter thickness.

shows the relationship between Since only the almost vertically transmitted light controlled by the liquid crystal display is scattered, the amount of light seen from any angle is approximately the same, and almost the same contrast can be obtained at any angle.

However, in the present invention, the light that is transmitted through the entire polarizing plate on the viewing plane, which disturbs the brightness of the pixels and causes a decrease in contrast ratio, is attenuated, and the transmission is controlled by the pixels. By scattering the light, it becomes possible to see the same from any angle, and as shown in FIG. 6, this has the effect of improving the viewing angle dependence of contrast.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing the structure of a liquid crystal display with a filter according to an embodiment of the present invention. The second figure is a schematic partially enlarged perspective view for explaining the entire filter used in one embodiment of the present invention. FIG. 3 is a schematic partially enlarged perspective view for explaining a filter used in another embodiment of the present invention. FIG. 4 is a schematic perspective view illustrating the effect of the filter-equipped liquid crystal display of the present invention. FIG. 5 is a graph for explaining the structure and function of the filter used in the present invention. FIG. 6 is a graph showing the viewing angle characteristics of the filter-equipped liquid crystal display of the present invention. Figure 7 is a schematic cross-sectional view showing the configuration of a conventional liquid crystal display. It is a schematic diagram to explain the visual dependence of a liquid crystal display. 100.400,700,800---Light source, 1
01,201...Filter, 102,202
, 302, 402, 702... Electrode substrate, 10
3,203,303,403,703...-Polarizing plate, 104,204,304,404,704...
...Transparent electrode, 105, 205, 305, 405, 70
5...Twisted nematic liquid crystal, 20
6,806...pixel, 207,307,407
・・・・・・Frame, 208°308.408・
...Transparent resin, 209,309,409...
...Scattering surface, 310...Absorption layer, 811...
...Liquid crystal display, 812...Oblique incident light, 813...Viewpoint when viewed from an angle, 11
4...Viewing surface, 215...Surface, 21
6... Back side, 317... Display part, 318... Part of filter, 319...
··hole. 6. T, -\. Agent: Patent attorney Susumu Uchihara (:・I). Early 3 Concave/F? Figure 4 Figure 6 Figure qo"oo Ri θ. Viewing angle <8)

Claims (1)

[Scope of Claims] 1. A liquid crystal display device, and a filter provided on a viewing surface of the liquid crystal display device, the filter having holes corresponding to the pixels of the liquid crystal display, and the filter having holes corresponding to the pixels of the liquid crystal display. A liquid crystal display with a filter, characterized in that an inner wall surface of the hole is made of a material having a large absorption rate in the visible light range, and a scattering surface is provided on the surface opposite to the side of the hole that is in contact with the viewing surface. 2. The liquid crystal display with a filter according to claim 1, wherein the hole of the filter is smaller in area than each pixel of the display. 3. The filter-equipped display according to claim 1 or 2, wherein the thickness of the hole in the filter is 0.7 or more of the longest planar length of the hole.