Variable-focal-length projection lens system and projection apparatus
US8699139B2 · kind B2 · utility
3Cited by
1References
21Claims
0Family size
Assignee
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Key dates
| Filing date | May 30, 2012 |
| Grant date | Apr 15, 2014 |
| Priority date | — |
| Expiry date | Oct 6, 2032 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B15/1465
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A variable-focal-length lens system for projection which achieves focusing by movement of the entire system has a second to a fourth lens group as focal-length-varying lens groups and a first lens group as a distance-compensation lens group. The second to fourth lens groups individually move in the optical axis direction to vary the group-to-group distances so as to vary the focal length of the entire system. During focusing, the first lens group moves in the optical axis direction such that, as the projection distance varies from a remote distance to a close distance, curvature of field varies to the under side.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.