Design and fabrication of a projection display using optically addressed polymer-dispersed liquid crystal light valves

Abstract

A prototype projection display consisting of optically addressed polymer-dispersed liquid crystal (PDLC) light valves and a Schlieren optics is designed, built, and evaluated. This projection display, which controls light by a scattering effect in the PDLC film, can be configured without requiring a polarizer and can create a brighter high- definition picture display with which high optical efficiency is possible. The relationship between the contrast ratio and the optical efficiency of a Schlieren projection system is discussed. To design a projection display with both high brightness and a high contrast ratio, the scattering characteristics of a reflection-mode PDLC cell is evaluated and the optical efficiency of the total projection system is studied using a simple model with perfect diffusion of a light source. Using these results, we design and prototype PDLC light valves for a full-color display and construct a projection display. We succeed in displaying pictures with a contrast ratio of 80:1 and a brightness greater than 1800 ANSI lumens.