Liquid crystal display

US5561540A · kind A · utility

Assignee

• Nokia Technology · DE

Inventors

• Stefan Brosig · Hankensbüttel, DE
• Jurgen Waldmann · Schönaich, DE

Key dates

• Filing date: Nov 3, 1994
• Grant date: Oct 1, 1996
• Expiry date: Nov 3, 2014

Classification

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

Abstract

According to the state of the art, LC displays are known whose torsion angle is between about 180.degree. and 300.degree.. Such displays exhibit good independence of angle of view of white impression and contrast, but they are not gray scale capable and are not free of hysteresis. For that reason, the invention presents a display (10) whose product of plate separation (d) and anisotropy of the angle of refraction is equal to or greater than 0.45 and smaller than 0.65 .mu.m, whose torsion angle .phi. is between 260.degree. and 360.degree., whose liquid crystal molecules (18) have an approach angle .theta. between 7.degree. and 25.degree., and encompass a liquid crystal material between the substrate plates (11) in which the relationship of the elastic constant K.sub.3 to the elastic constant K.sub.1 is between 1.4 and 0.6. The angular relationships (.beta., .gamma.) of the polarization directions P.u, P.o with the respective orientation direction .eta..u, .eta..o is a function of torsion angle .phi.. An improvement of the contrast relationships is provided, if the relationship between the upper polarization direction P.o and the lower polarization direction P.u is smaller than 90.de…