Liquid crystal projection display with even temperature elevation

Claim 1

A liquid crystal projection display apparatus, comprising: a thermally addressed liquid crystal light valve comprising in the following order a transparent substrate, a first transparent conductive layer, a light absorbing layer, a light reflecting layer, a first liquid crystal alignment layer, a liquid crystal material, a second liquid crystal alignment layer, a second transparent conductive layer and a transparent substrate; one of said first and second transparent conductive layers being provided with a thickness distribution which will cause the resistance distribution to stepwisely decrease from the center toward the periphery of said transparent conductive layers which causes resistive bending generated due to the supply of current to said one of said conductive layers to evenly elevate the temperature of a whole area of said liquid crystal material; a monochromatic light source; a light modulator for modulating a monochromatic light generated by said light source; a light deflector for deflecting said monochromatic light beam onto said light valve after it has been modulated by said light modulator; a source of projection light; a projection optical system for projecting said projection light onto said light valve; a voltage source for applying a voltage across either said first transparent conductive layer or said light reflecting layer and said second transparent conductive layer; and a current source for supplying a current pulse to said one of said conductive layers prior to a writing operation to cause said layer with distributed resistance to generate resistive heating that raises the temperature of said liquid crystal material, said current pulse being sufficiently short in duration that said liquid crystal material is changed in mode to a scattering state, and, after said scattering state has been attained, a writing operation may be performed to produce a positive image on a black background by addressing a message portion of said liquid crystal material in which a positive image is desired with light from said monochromatic light source and applying a voltage from said voltage source across either said first transparent conductive layer or said light reflecting layer and said second transparent conductive layer so as to render transparent and produce a positive image in said message portion of said liquid crystal material.