Black-white liquid crystal display having an insulation layer for blocking the diffusion of sodium ions from the glass of the cell plate to the polyphenylene of the orientation layer

US5071228A · kind A · utility

Assignee

• Nokia Unterhaltungselektronik GmbH · DE

Inventors

• Jurgen Waldmann · Schönaich, DE
• Stefan Borsig · Stuttgart, DE

Key dates

• Filing date: Dec 19, 1989
• Grant date: Dec 10, 1991
• Expiry date: Dec 19, 2009

Classification

• Technology area (CPC G): Physics
• CPC primary: G02F1/1397
• WIPO field: Optics
• WIPO sector: Instruments

Abstract

A black-white liquid crystal display (10) contains a nematic liquid crystal with a twist of 270.degree. between cell plates. The product of the liquid crystal layer thickness and anisotropy of the refractive index is about 0.38. A pretilt of about 15.degree. is present. The polarization directions (P1, P2) have an angle .beta. of 45.degree. to the orientation directions (Mo, Mu). This display features a very wide viewing angle range with relatively little dependence of the contrast on the viewing angle and there is an almost complete absence of color shift depending on the viewing angle. Due to the significant enhancement in viewing angle range in relation to contrast and color neutrality compared with all known cells, the display is called "Extended Viewing Angle" display (EVA display). It has a very high multiplexability.