Retrofocus projection lens system and multivision projection display apparatus
US5973848A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 8, 1997 |
| Grant date | Oct 26, 1999 |
| Priority date | — |
| Expiry date | Oct 8, 2017 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B13/22
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A retrofocus projection lens system comprising, in order from a large conjugate side a first lens group having a negative refracting power and including a plurality of lenses, a second lens group having a positive refracting power, and a third lens group having a positive refracting power and including a plurality of lenses. The lens of the first lens group which is nearest to the large conjugate side is an aspherical lens, and the lens of the third lens group which is nearest to a small conjugate side is an aspherical lens. The retrofocus projection lens system desirable satisfy the following conditional expressions (1) to (3): EQU 1.8<D.sub.1 /f<3.0 (1) EQU 1.1<f.sub.2 /f.sub.3 <1.6 (2) EQU 1.5<.vertline.f.sub.1 .vertline./f<2.3 (3) where a symbol f.sub.1 designates a focal length of the first lens group, a symbol f.sub.2 designates a focal length of the second lens group, a symbol f.sub.3 designates a focal length of the third lens group, a symbol f designates a focal length of the projection lens system, and a symbol D.sub.1 designates a gap between the first lens group and the second lens group.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.