Method and apparatus to minimize lamp flicker and increase contrast ratio in projection devices
US7570240B2 · kind B2 · utility
0Cited by
6References
16Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Aug 25, 2005 |
| Grant date | Aug 4, 2009 |
| Priority date | — |
| Expiry date | Aug 1, 2027 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02F1/136277
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A variable retarder is inserted in a polarized light beam. The retardance of the variable retarder is increased when the light beam increases in brightness and is decreased when the light beam decreases in brightness. The amount of increase and/or decrease in retardance is calculated to stabilize the brightness of the light beam. The variable retarder may be used in conjunction with an auto-iris and share a same brightness detector.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.