Liquid crystal display

Abstract

A liquid crystal display of the UV-phosphor type comprises a light source 1 for producing activation light at a predetermined narrow range of UV wavelengths, a collimator 3 for directing the activation light in parallel in a predetermined direction, a LC cell 5 formed from an array of pixels, a photoluminescent screen (7) on the cell arranged to emit a visible output when struck by the narrow-band excitation light passing through the cell, and a drive circuit for addressing the LC cell in a multiplexed manner. The direction of the light and the thickness of the cell are chosen to give the best contrast ratio for the liquid crystal. Such an effect is only possible when monochromatic, collimated light is used, which for a normal display is not practical. With the phosphor-emitter configuration, on the other hand, it is ideal, and as a result without loss of contrast a much lower range of drive voltages, and hence a much greater multiplexing capability for passive-matrix displays, can be used while preserving full viewing-angle properties of the display.

Dependencies are inferred from the claim text.