Transmissive polygonal optical scanning of illumination for light valve video projector
US5428467A · kind A · utility
Inventor
Key dates
| Filing date | May 20, 1993 |
| Grant date | Jun 27, 1995 |
| Priority date | — |
| Expiry date | May 20, 2013 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N9/3129
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A projection system employs a reflective light valve (10) that is optically addressed by an image from a cathode ray tube (12) and provides an output image for projection by means of a high intensity reading light from a lamp (16) directed to the output face of the liquid crystal light valve. Improved reading illumination is provided by scanning the face of the liquid crystal light valve (10) with a narrow beam of light (80) that moves across the liquid crystal light valve face in synchronism with a scanning image from the writing CRT (12). The scanned narrow band of illumination is provided by refractive transmission through a rotating transparent polygonal body (50,74) having pairs of mutually parallel sides (54,56,58,60,75,76,77a,b), wherein different pairs of sides may be made to transmit light of different colors for color projection. Rotation of the polygonal body is synchronized (82) with the vertical sync (86) of the CRT scan to cause the light beam refracted by the body to synchronously scan the face of the liquid crystal light valve.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.