New multicolor liquid crystal displays that use a twisted nematic electro-optical cell

Abstract

Two new variable color display device arrangements are described. These arrangements combine the unique polarization switching capabilities of the twisted nematic liquid crystal electro‐optical cell with the anisotropic optical properties of separate passive optical elements. In one scheme, the passive element is a birefringent film in combination with a neutral polarizer, and colors are transmitted by the selective interference of white light. In another design, where the passive element is a pleochroic filter, the transmitted colors result from the selective absorption of white light. These arrangements make possible large area displays, since the colors transmitted do not depend on the temperature or thickness of the nematic layer. Transmission curves and other color information are given for a number of examples.