JPH04372928A - liquid crystal display element - Google Patents

Abstract

PURPOSE:To efficiently guide the incident light to picture element opening sections and improve the intensity of a liquid crystal display element by provid ing an array of prism elements corresponding to the display elements, and making the width of the prism element smaller than the pitch of the prism elements. CONSTITUTION:When prism elements 105 are arranged, the width 112 of the prism element 105 is made narrower than the pitch 11 of the prism elements 105 and smaller than the value subtracted with the width 114 of a picture element opening section from a picture element pitch 113. The prism element 105 is made of two prisms, and the cross section shape of the two prisms is mirror-symmetrical. The incident light 107 permeating the picture element opening section when no prism element 105 is provided permeates the picture element opening section even when the prism element 105 is arranged. Part 109 of the incident light 108 shielded by a shield section 103 and a thin film transistor 102 is refracted by the prism element 105 to permeate the picture element opening section. The intensity of the image display surface can be improved.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display element.

0002

2. Description of the Related Art A problem to be solved with projection type liquid crystal display devices is that the brightness of projected images is low. In order to solve the above problem, proposals have been made to improve the brightness by forming a lens array in a liquid crystal display element and concentrating incident light on the liquid crystal pixel aperture. (For example, JP-A-57-157
215, Japanese Patent Publication No. 60-165624. )

0003

[Problems to be Solved by the Invention] However, since the proposals found in the prior art hardly take into account the characteristics of a series of optical systems including the light source, it is difficult to say that any of them are effective. The reason for this will be explained using FIG. 3. In a projection type liquid crystal display element, it is necessary to set an illumination optical system as shown in (A) in consideration of the angle of view of the projection lens and the size of the lamp. Here, 301 is a lamp, 302 is a condenser lens, and 303 is a liquid crystal panel. In such an illumination system, most of the light beams incident on the liquid crystal panel 303 are as shown at 304. Therefore, the angular component distribution of the incident light on the light incident surface of the liquid crystal panel 303 is as shown in (B), and the intensity of the incident light having an angle of 5 degrees or more is very strong. On the other hand, the thickness of the substrate on which the lens array is usually formed is about 1 mm, so if the size of the display pixel is about 100 μm x 100 μm, a lens body with a long focal length with an F number of about 6 to 8 is required. will be formed. long focal length lens body,
In other words, a lens body with a small numerical aperture (NA value) has a small angle of view and cannot efficiently guide light incident at a relatively large angle with respect to the optical axis of the lens to the liquid crystal pixel aperture. This situation is shown in FIG. The light rays 407 and 408 having a large incident angle are collected by the microlens 405, but most of them are blocked by the light shielding part 403.

0004

Means for Solving the Problems In order to solve the above problems, the liquid crystal display element of the present invention is provided with an array of prism elements corresponding to display pixels, and the width of the prism elements is It is characterized by being smaller than the pitch of the prism elements. Further, the prism element is characterized in that it consists of a combination of two prisms. Furthermore, when the pitch of the pixel openings of the liquid crystal display element is P, and the width of the light shielding part is W, the width of the prism element is P-W.
It is characterized by the following:

[0005]

[Example 1] Fig. 1 shows an outline of the prism array used in the example. The incident rays 107 to 110 are shown in FIG.
One of the incident angle components showing the maximum intensity shown in (B) is shown. Needless to say, the discussion to be described below also holds true for the other incident angle component. First, let us consider the case where there is no prism element 105. It is clear from the figure that 107 of the incident light rays 107 to 110 passes through the pixel opening 114, but 108 (109 and 110) are blocked by the light shielding part 103 and the thin film transistor 102. Next, consider the case where the prism element 105 is arranged. Here the width of the prism element is 112
is smaller than the prism element pitch 111, and the prism element width 112 is smaller than the pixel pitch 113 minus the pixel aperture width 114. Also, prism element 1
05 consists of two prisms, and the cross-sectional shapes of these two prisms are mirror-symmetrical. The light 107 that transmits through the pixel aperture even when there is no prism element transmits through the pixel aperture even when a prism element is arranged. On the other hand, of the incident light rays 108 that were blocked by the light shielding film and the thin film transistor, 1
09 is refracted by the prism element and transmitted through the pixel aperture, thus making it possible to improve the brightness of the image display surface.

(Example 2) A prism element as shown in FIG. 2 was manufactured. Here, the pixel pitch 206 is 56 μm,
The pixel opening width 208 is 30 μm, and the light shielding portion width 207 is 26 μm.
The distance 212 from the lower surface of the counter substrate 204 to the upper surface of the prism array substrate is 35 μm. The maximum angular components of the light incident on this prism array were +7° and -7°. Therefore, the prism element 203 was designed in accordance with this. The base angle of the prism on one side of the prism element is 210
3°, 211 is 19°, and the width of the prism element 209 is 26°.
It is μm. This was fabricated by etching a 7059 glass substrate 205. The brightness of the projected image when this prism element was used was 187 lm, which was 1.48 times brighter than when the prism element was not used. This is the end of the description of the embodiments in this patent, but for example, by changing the shape and pitch of the prism elements within the prism array surface according to the principal ray inclination of the projection lens, the brightness of the projected image can be further improved and the brightness can be reduced. Equalization is achieved.

[0007]

As described above, according to the present invention, by using a prism array having a simple configuration, light rays incident on a liquid crystal panel at an angle can be efficiently guided to pixel apertures. Therefore, by arranging the prism array of the present invention on the light source side of the liquid crystal display element, it is possible to improve the brightness of the projection type liquid crystal display element.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of Embodiment 1 of the present invention.

FIG. 2 is an explanatory diagram of Example 2 of the present invention.

FIG. 3 is an explanatory diagram of conventional technology.

FIG. 4 is an explanatory diagram of a conventional technique.

[Explanation of symbols]

101 Thin film transistor substrate 102 Thin film transistor 103 Light shielding part 104 Counter substrate 105 Prism element 106 Prism array substrate 107, 108, 109, 110 Incident light ray 111
Pitch of prism element 112 Width of prism element 113 Pixel pitch 114 Width of pixel opening 201 Light shielding part 202 Pixel opening 203 Prism element 204 Counter substrate 205 7059 glass substrate 206 Pixel pitch 207 Light shielding part width 208 Pixel opening width 209 Prism element Widths 210 and 211 Base angle of the prism 212 Distance from the bottom surface of the counter substrate to the top surface of the prism array substrate 301 Lamp 302 Condenser lens 303 Liquid crystal panel 304 Light rays incident on the liquid crystal panel 401 Thin film transistor substrate 402 Thin film transistor 403 Light shielding part 404 Counter substrate 405 Microlens 406 Microlens substrate

Claims (3)

[Claims] 1. A liquid crystal display element, characterized in that an array of prism elements is provided so as to correspond to display pixels, and the width of the prism elements is smaller than the pitch of the prism elements. 2. The liquid crystal display element according to claim 1, wherein the prism element is a combination of two prisms. 3. The prism element according to claim 1, wherein the width of the prism element is equal to or less than P−W, where P is the pitch of the pixel openings of the liquid crystal display element, and W is the width of the light shielding portion. liquid crystal display element.