JPH0762748B2 - Projection type liquid crystal display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] The present invention relates to a projection type liquid crystal display of a reflection type that utilizes a phase transition (cholesteric phase, manetic phase).
This prevents the liquid crystal layer in the pixel gap from becoming a scattering state and displaying unnecessary lines on the projection screen. In order to prevent the display of unnecessary lines, etc., a reflective layer is formed on the light incident side substrate of the liquid crystal panel in a shape corresponding to the pixel gap so that the incident light is reflected without being scattered. .

[Industrial application field]

The present invention relates to a method for improving the display quality of a reflection type projection liquid crystal display.

Although liquid crystal displays have been made larger, it has been difficult to apply them to a display device in which a large number of people view the panel itself at the same time due to crosstalk and limitation of viewing angle.
Therefore, an element that controls the liquid crystal panel to turn the light on and off,
There has been proposed a display device which is used as a so-called light valve and which magnifies and projects a pattern displayed on a liquid crystal panel with external light.

[Conventional technology]

FIG. 2 shows the shape of a liquid crystal panel used in a reflection type projection type liquid crystal display utilizing a conventional phase transition (cholesteric phase / manetic phase), and FIG. 3 shows the overall configuration of the display device.

As shown in FIG. 2 (a), the conventional liquid crystal panel 5 has two glass substrates 3 and 4 having parallel transparent electrodes 1 and 2 so that the transparent electrodes 1 and 2 are orthogonal to each other. They are superposed through a spacer.

FIG. 2B shows a plan view of a conventional liquid crystal panel. This liquid crystal panel 5 is inserted between the reflection plate 6 and the Fresnel lens 7 of the display device shown in FIG. To do. The display pattern of the liquid crystal panel is controlled by the drive circuit 10.

[Problems to be solved by the invention]

The relationship between the applied voltage and the light transmittance of the liquid crystal element of the phase transition (cholesteric phase and mannectic phase) is shown in FIG. The light transmittance is different when the applied voltage rises and when it falls, and has a hysteresis characteristic. The display of the pattern is to hold the points A and B in the drive circuit 10 in FIG.
Select the light scattering and light transmission of the liquid crystal element.

FIG. 5 shows an example of a conventional projection display pattern. In FIG. 5, 11 is a light scattering picture element and 12 is a light transmission picture element. Conventionally, as shown in FIG. 5, the peripheral portion of the picture element changes from the initial transparent state to the scattering state, and the grid pattern 14 appears. It is considered that this is because a transparent electrode in either the X direction or the Y direction runs in the pixel gap portion 13, and when a voltage is applied, the liquid crystal structure in this portion becomes a focal conic. In such a state, the drive circuit cannot control the original transparent state. Therefore, an unnecessary grid pattern is superimposed on the enlarged and projected pattern due to the light scattering of the picture element gap portion 13, and the display quality is deteriorated.

[Means for solving problems]

An object of the present invention is to solve the above-mentioned conventional problems, and this object is a reflection type projection liquid crystal display utilizing a phase transition of a cholesteric phase-manetic phase, on a substrate on the side where light is incident, This is achieved by a projection type liquid crystal display characterized in that a layer that reflects incident light is formed in a shape corresponding to a pixel gap of a liquid crystal panel.

[Action]

In the present invention, since the reflective layer is provided in the pixel gap portion of the liquid crystal panel, the light from the light source is directly reflected without passing through the liquid crystal layer. As a result, unnecessary grid-like patterns are not superimposed on the magnified projection surface as in the conventional case, and display quality can be improved.

〔Example〕

Next, examples of the present invention will be described. FIG. 1 shows a plan view of a liquid crystal panel of a projection type liquid crystal display of the present invention.

As shown in FIG. 1, a reflective layer 15 corresponding to the picture element gap portion 13 of the liquid crystal panel is formed in a grid pattern on the back surface (on the liquid crystal layer side) of the glass substrate 4 on the side where the light from the light source 8 is incident. Next, an example of the manufacturing method will be described. First, aluminum (Al) is formed on the glass substrate 4 by vapor deposition, and this is patterned to leave the reflective layer 15 in the form of a lattice. Next, a polyimide layer is formed on the entire surface of the grid-like reflective layer 15, and a transparent electrode is formed thereon as is conventionally done. The other glass substrate 3 side is the same as the conventional one.

If the reflectivity of the reflective layer is close to 100%, a bright grid pattern is displayed, and the display quality is degraded. Therefore, the display quality can be further improved by matching the reflectance of the reflective layer with the light transmittance of the liquid crystal element in the transparent state.
The light transmittance of a phase change type liquid crystal panel is usually about 80%. In the case of the reflection type, since the projection light passes through the liquid crystal panel twice, the substantial light transmittance of the projection light is about 64%.
The reflective layer may be formed by selecting the material and film thickness of the metal to be deposited.

〔The invention's effect〕

Use of the projection type liquid crystal display of the present invention has an advantage that the grid-like display pattern is removed and the display quality is remarkably improved.

[Brief description of drawings]

1 is a plan view of a liquid crystal panel of a projection type liquid crystal display according to an embodiment of the present invention, FIG. 2 is an explanatory view of a conventional liquid crystal panel, FIG. 3 is a configuration diagram of the projection type liquid crystal display, and FIG. 4 is a phase transition. Applied voltage-light transmittance characteristic diagram of the liquid crystal element, and FIG. 5 shows an example of a conventional projection display pattern. In the figure, 1,2
Is a transparent electrode, 3 and 4 are glass substrates, 5 is a liquid crystal panel, 8 is a light source, 13 is a pixel gap portion, and 15 is a reflective layer.

Claims (2)

[Claims] 1. A reflection type projection liquid crystal display utilizing a cholesteric phase-manetic phase transition, wherein incident light having a shape corresponding to a pixel gap of a liquid crystal panel is incident on a substrate on which light is incident. A projection type liquid crystal display characterized in that a reflective layer is formed. 2. The projection type liquid crystal display according to claim 1, wherein the reflectance of the layer that reflects the incident light is made equal to the transmittance of the light that the picture element of the liquid crystal panel shows in the transparent state.