Contrast improvement in liquid crystal light valve projectors
US6224215A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 12, 1999 |
| Grant date | May 1, 2001 |
| Priority date | — |
| Expiry date | Nov 12, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N5/74
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
The present invention relates to a light valve image projector with a disposition for improving the contrast of an optical image projected on a screen by that projector. The projector comprises at least one illumination system, at least one field lens, at least one set consisting of a polarizer, an LCD and an analyzer and at least a projection lens, and presents at least one optical axis which includes an angle .alpha. with the optical axis of the projection lenses. The invention consists in positioning the analyzer so that it includes an angle larger than .alpha. with the LCD, at least for the light rays that pass through the contrast limited area of the LCD. The invention consists furthermore in placing the polarizer so that it includes an angle larger than .alpha. with the LCD. Both the analyzer and/or the polarizer may have a flat or a curved surface.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.