Zoom lens for use in projection devices
US7440194B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Dec 18, 2007 |
| Grant date | Oct 21, 2008 |
| Priority date | — |
| Expiry date | Dec 18, 2027 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B15/145523
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An exemplary zoom lens for use in projection technology includes, in this order from the magnification side to the minification side thereof, a first lens group having negative refraction of power, a second lens group having positive refraction of power, a third lens group having positive refraction of power, a fourth lens group having negative refraction of power, and a fifth lens group having positive refraction of power, wherein the zoom lens satisfies the formulas: −1.5<F1/Fw<−1.3, 1.5<F2/Fw<1.8, 1.8<F3/Fw<2.2, −10<F4/Fw<−5, and 2.3<F5/Fw<2.8, where F1, F2, F3, F4, F5, and Fw respectively represent the effective focal length of the first lens groups, the second lens group, the third lens group, the fourth lens group, the fifth lens group, and the shortest effective focal length of the zoom lens.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.