Polymer dispersed liquid crystal panel with diffraction grating

Abstract

A layer having an irregular sectional surface is formed on the surface of at least one of a pixel electrode and confronting electrode of a liquid crystal layer so as to confront a liquid crystal layer. The liquid crystal layer is formed of a polymer dispersed liquid crystal. If the layer having an irregular sectional surface is formed in a convex and concave pattern regularly and cyclically, the thus formed layer serves as a diffraction grating. When the liquid crystal is in an OFF condition, the refractive index n of the diffraction grating is different from the refractive index of the liquid crystal layer. As a result, an incident light to the liquid crystal panel is scattered and at the same time, diffracted. When the liquid crystal in in an ON condition, there is no difference in the refractive index between the diffraction grating and the liquid crystal, and the incident light passes straight through. Using the liquid crystal panel as a light valve, the light from a light source is incident to the liquid crystal panel, and the image formed on the liquid crystal panel is projected through a projection lens onto a screen. In the case of a black display, the incident light is scattered or diffracted in the liquid crystal panel according to the projected image. The scattered or diffracted light is stopped by a light shielding part of a aperture, and thus does not arrive at the screen.