Twisted nematic liquid crystal display device

Abstract

Abstract The invention relates to electrically controlled display devices which use the polarisation rotation properties of layers of twisted nematic liquid crystal. The subject of the invention is a display device comprising an optical cavity formed by two polarisers (2, 5), which encloses a layer of twisted nematic liquid crystal and with which single-axis, birefringent means (11) are associated, for compensating for the residual birefringence of the liquid crystal layer, which tends to reduce the contrast ratio of the display device. The optical axis (OA) of these single-axis birefringent means is slightly inclined with respect to the normal to the main faces of the said layer. Hence, the homogeneity of the angular distribution of the contrast ratio is enhanced with respect to a device lacking compensator means. The invention may be applied, in particular, to data display devices for computers and to direct display or display by projection of television images. <IMAGE>

Inventors

• 👤 Gunther Haas

Bibliographic Details