Temperature compensating lens system for projection television
US5272540A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 13, 1991 |
| Grant date | Dec 21, 1993 |
| Priority date | — |
| Expiry date | Sep 13, 2011 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N9/31
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
In a projection lens device having at least two plastic lenses for magnification-projecting an original image displayed on a display screen onto a screen, one of the two plastic lens is convex at a center thereof toward the screen and concave at a periphery thereof, and the other lens has a weak positive refractive power toward the screen at a center thereof and a stronger positive refractive power at a periphery thereof. A variation of a lens power due to a change of a surrounding environment is cancelled out by the concave shape at the periphery of the one lens and the positive refractive power at the periphery of the other lens.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.