JPH02257119A - Liquid crystal display element - Google Patents

Abstract

PURPOSE:To maximize light transmission efficiency with various light sources by providing a lens array in which the pitch and radius of curvature of the individual microlenses constituting the lens array are changed according to the angle components of the incident light on the lens array so as to correspond to display picture elements. CONSTITUTION:The microlenses 205 are so disposed that the central parts of the microlenses 205 and the central parts of apertures 206 align in parts 201 where light sources are made incident perpendicular to the lens array. The central parts of the microlenses 205 and the central parts of the apertures 206 are deviated by partly forming the wide-pitch parts of the microlenses 205 with omitted parts 204 shown by, for example, broken lines in the parts 202 where rays are made incident diagonally on the lens array. The max. light transmission efficiency is obtd. If the pitch and curvature of the microlenses 205 in the respective intra-surface positions are changed to meet the incident angles of the rays having the max. intensity. The light quantity on the display surface is efficiently increased in this way.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a liquid crystal display element used in optical equipment such as liquid crystal displays, projection type projectors, and optical printers.

Problems to be solved with high-resolution liquid crystal display elements include improving the brightness and contrast on the display surface. In response to the above problem, proposals have been made to improve brightness and contrast by forming a lens array on the front surface (light source side) of a liquid crystal display element and concentrating incident light on the liquid crystal pixel opening. (For example, JP-A-57-1572
15, Japanese Unexamined Patent Publication No. 6O-165624). An outline of the conventional proposal will be explained below using FIG. 8. Lens array plate 80
Microlens 802 formed on 1 and transparent substrate 8
The two are configured so that the liquid crystal pixel apertures 804 formed on the microlenses correspond to each other, and the incident light 80 is
5 to one point on the liquid crystal pixel to improve the brightness and contrast on the display surface, a circular lens or a lenticular lens is used as the microlens for -r.

[Conventional technology]

[Problem to be solved by the invention] However, although the conventional proposals are certainly effective to some extent in improving the brightness and contrast of liquid crystal display elements, they do not require that the incident light be perpendicular to the lens array. Since the lens array was designed based on this assumption, it was not completely satisfactory.

In other words, as shown in FIG. 9, a light ray 902 (indicated by a dotted line in the figure) that is perpendicularly incident on the lens array 901 is
Although all of the light rays can pass through the liquid crystal pixel opening 903, a portion of the light ray 904 (indicated by a solid line in the figure) that enters at a certain angle is blocked by the light shielding film 905. Therefore, since a light source that emits light with various angular components is normally used, the ratio of the amount of light transmitted through the aperture of the liquid crystal display element to the amount of light in front of the lens array (hereinafter referred to as light transmission efficiency) is maximized. The problem was that it was not possible to do so.

SUMMARY OF THE INVENTION The present invention is intended to solve the above-mentioned problems, and its purpose is to provide a liquid crystal display element configuration that maximizes light transmission efficiency for various light sources.

[Means to solve the problem]

In order to solve the above problems, the liquid crystal display element of the present invention has the following features:
A lens array whose radius of curvature is changed according to an angular component of light incident on the lens array is provided so as to correspond to a display pixel.

[Effect]

The operation of the present invention will be explained with reference to the drawings. In Figure 1(a),
For the sake of explanation, a light beam incident surface 101 of a liquid crystal display element is shown divided into several blocks by diagonal lines or the like. The light intensity distribution along the dotted line 102 within the light incident surface 101 is shown in FIG. 1(b). Note that the horizontal axis of the graph in FIG. 1(b) indicates the in-plane position of the light incident surface 101, with the left end of the light incident surface 101 being 0 and the right end being 1. Also, the vertical axis is
Light intensity is shown in arbitrary units. Here, the straight line 106 is a ray whose incident angle on the ray incident surface 101 is 87° to 93°,
Dotted line 107 indicates rays from 84° to 87° and 93° to 96°, dashed line 108 indicates rays from 81° to 84° and 96° to 99°
shows the rays of light. As can be seen from FIG. 1(b), the in-plane position of the light beam incident surface 101 is 0.42 to 0.58 (FIG. 1(a)
), the angle of the ray with maximum intensity is 87° to 93°, and the in-plane position is 0.14 to 0.
42 and 0. 58-0. 86 (area 104 in FIG. 1(a)), 84° to 87° and 93° to 96
°, and in-plane position 0°0~0.14 and 0.86~1
．． 0 (area 105 in Fig. 1(a)) is 81°~
84° and 96° to 99°.

Therefore, the maximum light transmission efficiency can be obtained by matching the pitch and curvature of the microlenses at each in-plane position to the incident angle of the light beam having the maximum intensity. The method will be explained using FIG. 2.

FIG. 2 shows a cross-sectional view of a liquid crystal display element with a microlens. In the portion 201 where the light beam enters the lens array perpendicularly, the microlens 205 is arranged so that the center of the microlens 205 and the center of the aperture 206 coincide with each other.
Place. In the portion 202 where the light beam obliquely enters the lens array, for example, an omitted portion 204 indicated by a broken line
By creating a part of the microlens 205 with a wide pitch, the center part of the microlens 205 and the opening 2 are
Shift the center of 06. By doing so, even if the light rays are incident on the lens array obliquely, all the light rays can be made to enter the aperture 206. Part 20 where the incident is further oblique
3 can be treated in the same way. Further, in such a case, it is more effective to change the curvature of the microlens.

This will be explained using FIG. FIG. 3 shows a cross-sectional view of a portion where the center of the microlens 301 and the center of the opening 302 are offset. In FIG. 3(a), the center of the microlens 301 and the center of the aperture 302 are simply shifted, and the curvature of the microlens 301 is designed on the assumption that the light rays enter the lens array perpendicularly. It depicts a similar case. In such a case, the distance between the microlens 301 and the aperture 302 is longer than in the case where they are not shifted, so the light rays are directed toward the aperture 302.
The light is condensed in front of the light, and part of it is blocked by the light blocking section 303. However, even in this case, the microlens 30
Needless to say, the light transmission efficiency is higher than in the case where the center of the opening 302 and the center of the opening 302 are made to coincide with each other. In such a case, if the curvature of the microlens 304 is increased as shown in FIG. 3(b), the light rays will be focused at the center of the aperture 305, and loss of the scene can be eliminated.

〔Example〕

Hereinafter, the present invention will be described in detail based on Examples.

However, the present invention is not limited to the following examples.

[Example 1] FIG. 4(a) shows a light incident surface 401 of a liquid crystal display element whose plane is divided into several blocks by diagonal lines etc. for explanation.
shows. 403.404.4 in the plane of the light beam incidence surface 401
In the area 05, the relative positions of the center of the microlens and the center of the liquid crystal display element opening are different. As shown in FIG. 5, the center line 502 of the microlens 501 and the aperture 5
When the gap 505 formed by the center line 504 of 03 is d, in the region 403, d=o, 0 μm, and in the region 40
4, d=19.6μm, and region 405, d=4
It is 2.1 μm. Also, the width of each area is 403
=6. 4. mm, 404=11゜2 mm, 405=
It is 5.6 mm. Dotted line 4 within this light beam incidence surface 401
The light intensity distribution of the incident light from the light source along 02 is shown in Figure 4 (b
). Note that the horizontal axis of the graph in FIG. 4(b) indicates the in-plane position of the light beam entrance surface 401, with the left end of the light beam entrance surface 401 as the origin. Further, the vertical axis indicates the light intensity in arbitrary units. Here, the straight line 406 represents rays whose incident angles to the light incident surface 401 are 87° to 93°, the dotted line 407 represents rays whose incidence angles are 84° to 87° and 93° to 966°,
The one-dot chain line 408 is 81° to 84° and 96° to 99
Showing the rays of °. When the brightness of this liquid crystal display element was determined, the total amount of luminous flux transmitted through the liquid crystal display element was 268
1m was obtained. In addition, a display surface 601 shown in FIG. 6(a)
The brightness along the center line 602 was uniform over almost the entire surface, as shown by the solid line 603 in the graph of FIG. 6(b). (The brightness is set with the maximum brightness being 100.) By the way, the total luminous flux at the front position of the lens array is 30.
It is 01m. On the other hand, when a lens array was used in which the center of the microlens coincided with the center of the aperture over the entire surface of the lens array, the total amount of luminous flux transmitted through the liquid crystal display element was 2031 m. The brightness along the center line of the display surface is
As shown by the dotted line 604 in the graph of FIG. 6(b), it became darker toward both ends of the display surface.

[Example 2] A lens array was prepared in which the curvature of the microlenses of the lens array used in Example 1 was changed.

In FIG. 4(a), the radius of curvature of the microlens in region 403 was 161 μm, the radius of curvature of the microlens in region 404 was 162 μm, and the radius of curvature of the microlens in region 4050-8 was 163 μm.

As a result, the total amount of luminous flux transmitted through the liquid crystal display element is 2811
improved to m.

[Example 3] A lens array was manufactured in which the gap between the center line of the microlens and the center line of the opening (see 505 in FIG. 5) changes continuously. The pattern of change in the gap of this lens array will be explained using FIG. 7. The change in the gap along the center line 702 of the surface 701 on which the light rays of the lens array enter is shown in FIG. 7(b), and it changes continuously within the surface of the incidence surface 701. When this lens array was mounted on a liquid crystal display element and the brightness of the liquid crystal display element was determined, the total amount of transmitted luminous flux was 2721 m.

〔Effect of the invention〕

As explained above, according to the present invention, a lens array in which the pitch and radius of curvature of the microlenses constituting the lens array are changed according to the angular component of incident light is arranged on a liquid crystal display element so as to correspond to display pixels. By preparing for
It is possible to efficiently increase the amount of light on the display surface. It is clear that by using such a liquid crystal display element, it is possible to obtain an extremely high-brightness projection type projector, and furthermore, it is possible to apply it to optical printers, copying machines, general liquid crystal display devices, etc. be.

[Brief explanation of drawings]

FIGS. 1(a) and (b), FIG. 2, and FIGS. 3(a) and (b) are detailed explanatory diagrams of the present invention. Figure 4 (a)
(b), FIG. 5, and FIG. 6 (a) fb) are the first embodiments of the present invention.
An explanatory diagram of an example. FIGS. 7(a) and 7(b) are explanatory diagrams of a third embodiment of the present invention. FIG. 8 and FIG. 9 are explanatory diagrams of the conventional technology. 101...Light ray entrance surface 102...Dotted line 102 103...Region 103 104...Region 104 105...Region 105 407 ・ 408 ・ 601 ・ 602 ・ 603 ・ ・Light ray entrance surface・Dotted line 402 ・Area 403 - Area 404 - Area 405 - Light intensity of light rays with incident angles of 87° to 93°...Light intensity of light rays with incident angles of 84° to 87° and 93° to 96°...Incidence angles of 81' to 84° and Light intensity of 96° to 99° rays, microlens, centerline of microlens, aperture, centerline of aperture, gap between centerline of microlens and centerline of aperture, display surface, center Lines... Solid line 603 106... Light intensity of light rays with incident angles of 87° to 93° 107... Incident angles of 84° to 87° and 93° to 96
Light intensity of light beam of 108°...Incidence angle 81° to 84° and 96° to 99°
Light intensity of the light ray at 201...A portion where the light ray enters the lens array perpendicularly 202...A portion where the light ray enters the lens array obliquely 203...A portion where the light ray enters the lens array obliquely 204...Omitted Portion 205... Microlens 206... Opening 207... Omitted portion 301... Microlens 302... Opening 303... Light blocking portion 304... Microlens 305...・・Aperture・Dotted line 604・Light ray incident surface・Center line・Lens array plate・Microlens・Transparent substrate・Liquid crystal pixel aperture・Incoming light・Light shielding film・Pixel electrode・Switching element・Lens array・For lens array Light rays 903 incident perpendicularly to the liquid crystal pixel aperture 904...Light rays 905 incident at a certain angle to the lens array...More than the light-shielding film -14= Fig. 3 Figure ≠ 0 / ■ / 1-22 / / m= /- ::= / ′=== : / / Eiri //A// Lo3 4ρ, It(=2 40 da 0ri Figure 4 3“ Figure 8

Claims (1)

[Claims] A lens array in which the pitch and radius of curvature of individual microlenses constituting the lens array are changed according to the angular component of the light incident on the lens array is provided so as to correspond to the display pixels. Characteristic liquid crystal display element.