JPH0153444B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a transmission type liquid crystal display device,
In particular, the purpose is to improve the brightness of the display surface.

FIG. 1 is a schematic cross-sectional view of a conventional transmissive liquid crystal display device, in which display pixel-shaped electrodes 2 are formed facing inside two parallel glasses 3 to which a polarizer 4 is closely attached. It also includes a liquid crystal panel 5 in which a liquid crystal 1 is sealed in a gap between the glasses 3, and a lighting device 6 for illuminating the liquid crystal panel 5.

In addition, in Figure 1, the transparent part that transmits light is 1
a. The non-transparent part is the part shown by 1b.

Here, in the liquid crystal panel 5, since the liquid crystal 1, electrodes 2, glass 3, polarizer 4, etc. are all transparent, the reflectance can be expected to be only a small value based on Fresnel's equation.

In the conventional transmissive liquid crystal display device having the structure shown in FIG. 1, most of the light from the illumination device 6 enters the liquid crystal panel 5, and the amount of light obtained as a function of the voltage applied to the electrode 2 is transmitted through the transparent portion 1a. , most of it will be absorbed in the non-transparent portion 1b.

The present invention utilizes the light that is incident on the non-transparent portion 1b and is absorbed in the above description to make the display surface brighter, and the details thereof will be explained with reference to FIG.

FIG. 2 is a schematic cross-sectional view showing an embodiment of a transmissive liquid crystal display device according to the present invention. It has a structure in which a two-layer reflective surface treatment is applied, with the black reflective surface 7b facing the device 6 side and the opposite liquid crystal panel 5 side, and the other parts have the same structure as in FIG.

The effect of the white reflective surface 7a in the transmission type liquid crystal display device of FIG. 2 is as follows.

The total area of the liquid crystal panel 5 is Sa, the white reflective surface 7a
Assuming that the area is Sw, the reflectance is ρw, the reflectance of the light-diverging portion of the lighting device 6 _{is ρL} , and the direct illuminance of the liquid crystal panel 5 due to the direct light from the lighting device 6 is _Ep , the white reflective surface 7a is provided. Illuminance E of the liquid crystal panel 5 due to
is approximately given by the following equation (1).

E=Eo/1-ρw・Sw/Sa・_ρL ...(1) Therefore, the increase in illuminance, that is, the effect of the white reflective surface 7a, is E/Eo=1/1-Sw/Sa・_ρW・_ρL …(2) becomes.

Here, by substituting specific numerical examples Sa = 1 Sw = 0.5 (values of general Kusegment numerical display) ρw = 0.8 ρ _L = 0.4 into formula (2) above, E/Eo = 1/1 - 0.5 ×0.8×0.4=1.19, which means that there is an increase in illuminance of about 19%, that is, an increase in the amount of transmitted light toward the viewer, and a brighter display effect can be obtained.

Next, the effect of the black reflective surface 7b is qualitatively as follows.

Light that enters the liquid crystal panel 5 from the viewer side enters the black reflective surface 7b and is absorbed, so the brightness ratio between the transparent portion 1a and the non-transparent portion 1b, that is, the contrast ratio increases, resulting in a clearer image. Display effects can be obtained.

As explained above, in a transmissive liquid crystal display device having a liquid crystal panel provided with a reflective surface according to the present invention, a brighter display can be obtained by the white reflective surface, and a clearer display with a high contrast ratio can be obtained by the black reflective surface. This has the effect of providing a clear display.

[Brief explanation of drawings]

FIG. 1 is a schematic sectional view of a conventional transmission type liquid crystal display device, and FIG. 2 is a schematic sectional view showing an embodiment of the transmission type liquid crystal display device of the present invention. In the figure, 1 is a liquid crystal, 1a is a transparent part, 1b is a non-transparent part, 2 is an electrode, 3 is glass, 4 is a polarizer, 5 is a liquid crystal panel, 6 is a lighting device, 7 is a reflective surface, and 7a is white Reflective surface 7b indicates a black reflective surface.

Claims (1)

[Claims] 1. In a transmissive liquid crystal display device having a liquid crystal panel and a lighting device on the back side of the liquid crystal panel, on the surface of the liquid crystal panel facing the lighting device, the liquid crystal panel side covers the non-transmissive portion excluding the transparent portion that transmits light. A transmissive liquid crystal display device characterized in that the reflective surface has a two-layer structure, with a black reflective surface and a white reflective surface on the illumination device side.