Enhanced contrast liquid crystal display device
US5018837A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 3, 1989 |
| Grant date | May 28, 1991 |
| Priority date | — |
| Expiry date | Jul 3, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02F2203/02
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
Known LCD devices of the type having an upper polarizer (36), a liquid crystal cell (28), a lower polarizer (38) and a reflector (42) and working using ambient light to provide illumination lose contrast because the light passes twice through both polarizers. By providing a layer of light concentrating plastic (44) between the upper polarizer (36) and the LCD cell (28), light emitted from bevelled edges (48) of an aperture (46) in the plastic is directed towards the cell and reflector directly, without passing through the upper polarizer (36). This is in addition to the normal ambient light passing through the front polarizer. This increases the intensity of light reaching the observer (20) and thus the contrast of the display.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.