Contrast enhancement and ghost elimination, for reflective light valve system
US5268775A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 22, 1992 |
| Grant date | Dec 7, 1993 |
| Priority date | — |
| Expiry date | Dec 22, 2012 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N9/3167
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A reflective liquid crystal light valve projection system employs a polarizing beam splitter (16) to reflect light from a high intensity arc lamp (10) to a liquid crystal light valve (34) that is controlled by an image generator (36). Light reflected from the liquid crystal light valve is transmitted through the polarizing beam splitter (16) to a projection lens (38) and projected on a screen. Ghost images of the arc lamp source and diminished contrast are caused by light reflected from surfaces of the lens elements back to the liquid crystal light valve and then retroreflected back through the lens. The ghost images and diminished contrast are eliminated by interposing a broad band quarter wave plate between the lens and the polarizing beam splitter.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.