Current Status of Dichroic Liquid Crystal Displays

Abstract

This paper reviews the operational principle, construction and electro-optical performance of various types of dichroic liquid crystal displays such as Heilmeier, phase change, dye doped TN and polymer dispersed dichroic. It also discusses the double layer and positive mode dichroic LCDs. The impact of material properties such as birefringence, dielectric anisotropy, viscosity, elastic constant and cell construction such as alignment, cell gap, etc., on the electro-optical performance of these displays has been mentioned. The contrast ratio, viewing angle, switching speed, etc., of Heilmeier, phase change and dye doped TN have been discussed. The data indicate dye doped TN to be a display with very high contrast (> 100:1) and a much wider viewing angle compared to TN display. The colour shift with viewing angle is also found to be much less for dye doped TN than for normal TN liquid crystal displays. Some of the applications of current dichroic displays are shown, and potential future applications are suggested.