Long focal length projection lenses
US6301057A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jan 31, 2000 |
| Grant date | Oct 9, 2001 |
| Priority date | — |
| Expiry date | Jan 31, 2020 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B13/16
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A projection lens for use with LCD or DMD panels is provided. The lens has three lens units, the first unit having a weak power and at least one aspheric surface, the second unit having a positive power, a high dispersion negative lens element, and a low dispersion positive lens element, and the third unit having a negative power, a positive meniscus lens element and a negative lens element. The projection lens satisfies the following relationships: PA1 f.sub.0 /.vertline.f.sub.1.vertline.<0.6; and PA1 BFL/f.sub.0 >0.3 where (i) f.sub.0 is the effective focal length of the combination of the first, second, and third lens units; (ii) f.sub.1 is the effective focal length of the first lens unit; and (iii) BFL is the back focal length of the combination of the first, second, and third lens units for an object located at infinity along the long conjugate side of the projection lens.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.