JPH05249450A - Liquid crystal display - Google Patents

Abstract

PURPOSE:To provide a high transmissivity and fine image brightness even in a light shielding layer having the same opening rate by making the area of a incident surface of an optical waveguide transmitting light in the direction of a base board normal line in one base board larger than the area of a light- emitting surface of a shape including in the display area of a picture element part. CONSTITUTION:The optical waveguide 102 is formed in the direction of the base board normal line in one substrate 101 and the area of the incident surface 103 to the optical waveguide 102 provided at the incident side of light is constituted larger than the area of the light-emitting surface 104 from the optical waveguide 102 in the substrate 101. When the light is made incident on vertically like arrows, almost amount of the light coming into the incident side of the substrate 101 is closed by the optical waveguide 102 and advanced, then the light is focused and emitted from the light-emitting surface 104. Consequently, by including the shape of the light-emitting surface 104 in the surface of the substrate 101 in the display part 105, almost amount of the incident light transmits and a large amount of transmitting light is obtained without being affected by the size of the picture element.

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 device.

[0002]

2. Description of the Related Art High-definition active matrix liquid crystal display devices are required. In particular, the demand for applying liquid crystal display devices to high-definition televisions and engineering workstations tends to increase year by year (Flat Panel Display, 1991, p. 193, Nikkei BP).

[0003]

Generally, one pixel of a liquid crystal display device comprises a non-display portion and a display portion. Therefore, the transmittance of the liquid crystal display device is proportional to the aperture ratio (the area ratio of the non-display portion to the area of the pixel size). As shown in FIG. 2, a non-display portion of a liquid crystal display device in which a liquid crystal 204 is sandwiched between transparent substrates 205 and 206 includes a wiring 201, a pixel driving element 202 such as a thin film transistor or a diode, a light shielding layer 203, and the like.

Now, consider the case where the size of one pixel is reduced. In this case, the area of the non-display portion cannot be simply reduced. This is because the lower limit of the area of these non-display areas is determined by the processing accuracy of wirings and pixel driving elements and the assembly accuracy of substrates.

Therefore, the aperture ratio of the liquid crystal display device sharply decreases as the size of one pixel is reduced. Therefore, when a high-definition liquid crystal display is created, it is difficult to obtain a very dark display screen.

[0006]

A liquid crystal display device of the present invention has an optical waveguide for transmitting light in a substrate normal direction in one substrate, and an incident surface area of the optical waveguide is an emission surface of the optical waveguide. The shape is larger than the area and the shape of the emission surface is included in the display region of the pixel portion.

[0007]

The present invention will be described with reference to FIG. In the present invention, the optical waveguide 102 is formed in the one substrate 101 in the substrate normal direction. In this structure, the area of the incident surface 103 of the substrate on the light incident side of the optical waveguide 102 is larger than the area of the light emitting surface 104 of the substrate on the light emitting side of the optical waveguide 102. ..

Therefore, when light is vertically incident on the liquid crystal display device of FIG. 1, most of the light reaching the light incident side of the substrate is confined in the optical waveguide 102 and travels.
While advancing through the optical waveguide, the light is focused and emitted from the emission surface 104 from the optical waveguide.

Therefore, by making the shape of the light emitting surface 106 in the substrate surface to be included in the display portion 105 of the liquid crystal display device, most of the incident light can be transmitted. Therefore, a large amount of transmitted light can be obtained regardless of the pixel size.

[0010]

EXAMPLE An example of the present invention will be described with reference to FIG. An optical waveguide substrate 3 having an optical waveguide 306 as shown in FIG.
03, a light shielding layer 304 made of a chromium thin film and a rubbed polyimide thin film 305 were laminated. Here, the light incident surface of the waveguide 303 is a square having a side of 100 μm and is arranged at a pitch of 100 μm. Therefore, the light incident surface of the optical waveguide substrate 303 is entirely covered with the light incident surface of the waveguide.

On the other hand, the light emitting surface of the waveguide 303 has one side 3
The squares are 0 μm square and are arranged at a pitch of 100 μm. Further, the opening of the light-shielding layer 304 is a square having a side of 40 μm and is aligned with each optical waveguide 303 as shown in FIG.

Further, a rubbed polyimide thin film 30 is used.
2 laminated glass substrate 301 and optical waveguide substrate 303
Were made to face each other at intervals of 5 μm using a plastic spacer, and nematic liquid crystal E8 was injected between them to realize a TN structure 307. The liquid crystal cell having this structure was placed between the orthogonal polarizing plates 308, and the transmittance at 550 nm was determined. As a result, a transmittance of 20% was confirmed.

For comparison, a liquid crystal cell was prepared in which a glass substrate having light-shielding layers of the same size laminated was used as a substitute for the optical waveguide substrate 303, and the transmittance was similarly obtained. As a result, a transmittance of 5% was confirmed.

The optical waveguide substrate 303 used in the above embodiment can be manufactured by various methods. An example thereof is shown in FIGS.

FIG. 4 shows an example of manufacturing an optical waveguide substrate by a molding method. First, as shown in FIG. 4A, the photosensitive resin A is applied onto the resin B and exposed through a mask. Then, as shown in FIG. 4B, the photosensitive resin A is developed to develop the photosensitive resin A.
After patterning, the photosensitive resin A is molded with the resin B (FIG. 4C). Finally, the resin B is removed by etching or polishing to expose the end face of the photosensitive resin A to form an optical waveguide substrate (FIG. 4 (d)).

FIG. 5 shows an example of producing an optical waveguide substrate by the ion diffusion method. First, as shown in FIG. 5A, a photosensitive resin is formed in a pattern on a glass substrate. Next, as shown in FIG. 5B, after ion diffusion, the photosensitive resin is removed to obtain an optical waveguide substrate (FIG. 5C).

[0017]

As described above, by using the present invention, it is possible to obtain a practically high transmittance while having a light shielding layer having the same aperture ratio. This indicates that the present invention is effective for improving the screen brightness of a high-definition liquid crystal display device.

[Brief description of drawings]

FIG. 1 is a sectional view for explaining the present invention.

FIG. 2 is a sectional view for explaining a conventional technique.

FIG. 3 is a sectional view for explaining an embodiment of the present invention.

FIG. 4 is a diagram showing an example of manufacturing an optical waveguide substrate.

FIG. 5 is a diagram showing an example of manufacturing an optical waveguide substrate.

[Explanation of symbols]

 101 Substrate 102 Optical Waveguide 103 Incident Surface 104 Emission Surface 105 Display Unit 106 Liquid Crystal Layer 107 Transparent Substrate 201 Wiring 202 Pixel Driving Element 203 Light Shielding Layer 204 Liquid Crystal Layer 205 Transparent Substrate 206 Transparent Substrate 301 Glass Substrate 102 Polyimide Thin Film 303 Optical Waveguide Substrate 304 Light Shading Layer 305 Polyimide thin film 306 Optical waveguide 307 TN structure 308 Polarizing plate

Claims (1)

[Claims] 1. A liquid crystal display device in which a liquid crystal is sandwiched between two transparent substrates, wherein one substrate has an optical waveguide for transmitting light in a normal direction of the substrate, and an incident surface area of the optical waveguide is the optical waveguide. A liquid crystal display device characterized in that the shape of the exit surface is larger than the exit surface area of the waveguide and is included in the display region of the pixel portion.