JPS6440819A - Liquid crystal light valve - Google Patents

Abstract

PURPOSE:To form an optical system of inexpensive structure and to simplify reading out by incorporating dichromatic dyes into an optical writing type liquid crystal light valve formed by using a photoconductor. CONSTITUTION:This light valve is constituted of the substrate which is formed by laminating a photoconductor layer 104 and a translucent mirror 103 on a transparent glass substrate 106 provided with transparent electrodes 105, a transparent glass substrate 106 which is provided with transparent electrodes 106 and faces said substrate and the nematic liquid crystal which is held in place between two sheets of these substrates and contains the dichromatic dyes. The part projected with writing light 108 acts as a low resistance when said light is projected to the photoconductor layer. The partial voltage ratio of the voltage impressed over the entire part is, therefore, changed and the voltage larger than the voltage at the dark time is impressed to the liquid crystal layer. A change in orientation is generated in the liquid crystal molecules and the arrangement direction of the dichromatic dye molecules 102 is correspondingly changed when this voltage exceeds the threshold voltage of the electro- optic effect of the liquid crystal. The light absorption at the point irradiated with the writing light is thereby decreased and the image is formed by the difference between the light absorption and optical density of the non-irradiated point.