JPH05150231A - Liquid crystal display element - Google Patents

Abstract

PURPOSE:To improve a light shielding film so as to enhance light trasnsmissivity. CONSTITUTION:The light shielding film 2 is formed on a side on which the light of a back light 15 outside a lower transparent substrate 1 is made incident, and formed of material having high reflectance. Thus, the substantial aperture rate of the film 2 becomes large, the light transmissivity of a liquid crystal display element is improved, thereby improving visibility and reducing the power consumption of the backlight 15.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in display quality of a liquid crystal display device, particularly a color liquid crystal display device.

[0002]

2. Description of the Related Art The light transmittance of a liquid crystal display device is as low as about 3.5%, and it is difficult to increase the light transmittance significantly to improve the visibility. Therefore, it is generally performed to increase the brightness by using a backlight, and it is indispensable for a color liquid crystal display device. Since luminance of about 80 cd / m ² is required on the surface of the liquid crystal display element in order to obtain practically sufficient visibility, the surface luminance of the backlight is 230 when the above transmittance is satisfied.
About 0 cd / m ² is required, and the power consumption of the backlight becomes considerably large for a large display element. For this reason,
Although the liquid crystal display element itself consumes very little power, it consumes a large amount as a whole. In particular, battery-powered portable devices and the like have problems such as shortened battery life, and it is desired to improve the light transmittance and reduce the power consumption of the backlight by improving the liquid crystal display element.

FIG. 3 is a schematic sectional view of a conventional simple matrix type color liquid crystal display device with a backlight. Each pixel of the light shielding film 2 and the color filter 3 is formed on the inner surface of the lower transparent substrate 1, and the overcoat layer 4, the transparent electrode 5, and the alignment film 6 are further formed thereon, and the other upper transparent substrate 7 is formed. A transparent electrode 8 and an alignment film 9 are formed on the inner surface of the substrate, a liquid crystal layer 10 is provided between the substrates 1 and 7, and the peripheral edge is sealed with a sealing material 11. A backlight 15 is arranged outside the lower transparent substrate 1, and is composed of a cold cathode tube 16, a light guide plate 17, a reflection plate 18, a diffusion plate 19, and the like. In addition, 12 is a polarizing plate and 13 is a retardation film.

[0004]

The light-shielding film 2 is necessary together with the color filter 3, and the aperture ratio of this light-shielding film is usually around 66%, which lowers the light transmittance of the liquid crystal display element. This is one of the causes, and it is considered that increasing the light transmittance of the light shielding film is very effective in solving the above-mentioned problems. In view of this point, the present invention has been made to improve the light transmittance by improving the light-shielding film.

[0005]

In order to solve the above-mentioned problems, according to the present invention, a liquid crystal layer is interposed between two transparent substrates facing each other, and a transparent substrate on the side where backlight light is incident. In a liquid crystal display element having an inner surface coated with a color filter, a light-shielding film provided between pixels of the color filter is coated on the outer surface of a transparent substrate on which the color filter is coated, and the light-shielding film is raised. It is made of a material having a reflectance.

[0006]

The light-shielding film in the conventional liquid crystal display element is formed on the inner surface of the transparent substrate as illustrated in FIG. 3, and a light-absorbing material is used due to restrictions of the forming method. According to the present invention, since the light-shielding film having a high reflectance is formed on the outer surface of the transparent substrate on the side where the backlight light is incident, the light incident from the backlight is not absorbed and the reflection is repeated to make the final light. As a result, most of the light is incident on the color filter, which increases the light transmittance and improves the visibility.

[0007]

Next, an embodiment of the present invention will be described. FIG. 1 is a schematic sectional view of an embodiment corresponding to FIG.
The same reference numerals are attached to the same portions. As shown in the figure, in this embodiment, the light-shielding film 2 is formed on the polarizing plate 12 outside the lower transparent substrate 1, and a considerable part of the light incident from the backlight 15 is indicated by the broken line in FIG. As shown by an arrow A, the light does not hit the light-shielding film 2 and directly enters the transparent substrate 1 through the polarizing plate 12. Further, the light that has hit the light-shielding film 2 is reflected by the light-shielding film 2 as indicated by the solid arrow B, and is repeatedly reflected between the light-reflecting plate 18 and the diffuser plate 19 of the backlight 15, etc. Most of the light is absorbed but directly enters the transparent substrate 1 through the polarizing plate 12. Therefore, the substantial aperture ratio of the light shielding film 2 is significantly improved as compared with the conventional one, and the light transmittance of the liquid crystal display element can be increased, and the visibility is improved with the same backlight. If the same visibility is sufficient, the power consumption of the backlight can be reduced.

By the way, in the embodiment, by using chromium having a high reflectance as the material of the light-shielding film 2, the substantial aperture ratio can be increased to about 90%, which is improved by about 36% from the conventional 66%. We were able to. For example, if the transmittance of the polarizing plate 12 is 5
The transmittance before entering the color filter 3 when the transmittance of the transparent substrate 1 is 0% and the transmittance of the transparent substrate 1 is 100% is as follows when compared with the conventional example. That is, in the example, 0.9 × 0.5
× 1.0 = 45%, whereas in the conventional example, 0.5
X1.0 * 0.66 = 33%, and in the example, the transmittance is improved by 36%. The present invention can be applied to both side edge type and direct type backlights.

[0009]

As is apparent from the above-described embodiments, the present invention has a liquid crystal layer interposed between two transparent substrates facing each other, and a color is formed on the inner surface of the transparent substrate on which the backlight light is incident. In a liquid crystal display device with a filter attached, a light-shielding film provided between each pixel of the color filter is attached to the outer surface of the transparent substrate with the color filter attached, and the light-shielding film has a high reflectance. It is made of a material that has. Therefore, the substantial aperture ratio of the light-shielding film is increased and the light transmittance of the liquid crystal display device is improved. Therefore, it is possible to improve the visibility by transmitting a large amount of backlight light and increasing the brightness of the device surface. Alternatively, the power consumption of the backlight can be reduced, and the battery life can be extended particularly in battery-powered portable equipment.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an embodiment of the present invention.

FIG. 2 is an operation explanatory diagram of the embodiment.

FIG. 3 is a schematic cross-sectional view of a conventional example.

[Explanation of symbols]

 1 Lower transparent substrate 2 Light-shielding film 3 Color filter 12 Polarizing plate 15 Backlight

Claims (1)

[Claims] 1. A liquid crystal display device comprising a liquid crystal layer interposed between two transparent substrates facing each other, and a color filter attached to the inner surface of the transparent substrate on which the backlight light is incident. A liquid crystal display characterized in that a light-shielding film provided between pixels of a color filter is applied to the outer surface of a transparent substrate to which the color filter is applied, and the light-shielding film is formed of a material having high reflectance. element.