Light valve having reduced reflected light, high brightness and high

Abstract

In a light valve, a liquid crystal layer made of liquid crystal/resin composite is interposed between a transparent substrate with a counterelectrode and a reflection substrate with reflection electrodes. The size of the transparent substrate is designed so that the light modulated by the liquid crystal layer is prevented from again entering into the liquid crystal layer after reflected at an interface of the transparent substrate with air. The transparent substrate may be combined with a transparent plate or flat concave lens with a transparent coupling material. Each pixel has a reflection electrode and liquid crystal molecules above the reflection electrode are aligned according to the signals supplied to thin film transistors. The counterelectrode is formed as a multi-layer film of dielectric films and a transparent electrically conductive film. The dielectric films are made of a material having a refractive index of 1.6-1.8, and the optical thickness of the dielectric films is .lambda./4 while that of the transparent electrically conductive film is .lambda./2. Thus, the reflection of light is prevented by the interference in the multi-layer film. By using the light valve apparatus, the incident light entering from the side of the counterelectrode is scattered or it is transmitted through the liquid crystal layer, reflected by the reflection electrodes and leaves through the counterelectrode. By using the light valve apparatus in a projection display system, an image of high brightness and high contrast can be realized.