Cholesteric reflective display: Drive scheme and contrast

Abstract

We studied the electro-optical response of a bistable cholesteric texture (BCT) display to ac voltage pulses. The material can be driven into states where planar and focal conic textures coexist at zero field and gray scale memory is achieved. According to the properties of the BCT display we designed two drive schemes; one for binary operation and the other for gray scale operation. We made a 320×320 pixel reflective display with a resolution of 80 lines/in. on a passive matrix. Measurement in an integration chamber showed that the display has higher contrast and better viewing angle than a reflective super twisted nematic display.