Liquid crystal display device and phase plate therefor
US5220447A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Mar 16, 1990 |
| Grant date | Jun 15, 1993 |
| Priority date | — |
| Expiry date | Mar 16, 2010 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02F2413/01
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A liquid crystal display device comprising: a liquid crystal display element formed by holding, between two substrates at least one of which has a light-permeable electrode, a liquid crystal layer in which liquid crystal molecules of a nematic liquid crystal having positive dielectric anisotropy and containing an optically active substance has a helical axis perpendicular to the substrates between the substrates and are helically oriented, and the liquid crystal molecules between the substrates have a twist angle of 180 to 270 degrees, and a phase plate formed by stacking water surface development films of an organic polymer with changing the orientation axes thereof at a constant angle, wherein the contrast ratio, a ratio between brightness in white display and brightness in black display, is remarkably excellent over that of a device obtained by stacking plastic films, and the transmissivity, a quotient of background brightness and light source brightness, is equivalent to that of a conventional double layer structure liquid crystal display device.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.