Viewing angle characteristics of a twisted nematic (TN) liquid-crystal display (LCD) have been improved by inserting a planar aligned cholesteric liquid crystal compensating layer between the TN cell and a polarizer. Dependencies of the electro-optical characteristics of the novel LCD on the retardation, ratio of thickness to the pitch (dc/p) and twist-sense in the cholesteric layer are discussed. A thin-film transistor addressed LCD with a wide viewing angle has been developed based on this novel cell construction and its display performance is reported.

Abstract— A new evaluation method of viewing‐angle characteristics for liquid‐crystal displays (LCDs) with gray‐scale images has been studied. In this method, reverse images, excessively dark images, and excessively bright images, which are a serious problem while displaying gray‐scale images, are evaluated quantitatively along with the display contrast ratio. The viewing‐angle characteristics of several types of LCDs are compared using this method.

Abstract— The viewing‐angle characteristics of a TN‐LCD were improved by inserting an ultra‐super‐twisted (UST) liquid‐crystal compensating layer between the TN cell and one of the polarizers. The viewing‐angle characteristics of the LCD could be controlled by changing the optical conditions of the UST layer, such as the retardation, the dUST/p value, and the twist sense. The improved viewing‐angle characteristics were confirmed by a TFT‐addressed LCD developed on the basis of this novel cell construction.