Optical overhead projector for electronic images
US5260730A · kind A · utility
7Cited by
4References
10Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Jan 25, 1993 |
| Grant date | Nov 9, 1993 |
| Priority date | — |
| Expiry date | Jan 25, 2013 |
Classification
- Technology area (CPC Y)Emerging Cross-Sectional Technologies
- CPC primaryY10S353/03
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A relatively small liquid-crystal display (LCD) device located well above the fresnel stage of an overhead projector produces large, sharp images with full color and motion. A focus-correcting lens moves with the overhead projector's optical head to maintain proper projection-focus and magnification. Spectrally-selective filters are interposed between the LCD device and fresnel stage to avoid LCD deterioration. A fan-actuated shutter or electrically-actuated shutter optionally provide still further protection. Optical collimation methods are employed to attain a large depth-of-field and image brightness.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.