Projection lens with high resolution and reduced overall length
US7580194B2 · kind B2 · utility
Assignee
Inventor
Key dates
| Filing date | Dec 12, 2007 |
| Grant date | Aug 25, 2009 |
| Priority date | — |
| Expiry date | Dec 12, 2027 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B15/1425
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An exemplary projection lens includes, in this order from the screen-side thereof, a negative lens group having negative refraction of power, and a positive lens group having positive refraction of power. The positive and negative lens groups each include a number of positive and negative lenses. The focal length of the projection lens is adjustable. The projection lens satisfies the formulas of: −2<F1/Fw<−1.6; 1.2<F2/Fw<1.4; and Vg2>56, where F1, and F2 respectively represent the effective focal lengths of the negative lens group and the positive lens group, Fw is the shortest effective focal length of the projection lens, and Vg2 is the average of the Abbe numbers of the positive lenses in the positive lens group.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.