Compact projection lens
US4690515A · kind A · utility
6Cited by
4References
16Claims
0Family size
Assignee
Inventors
Key dates
| Filing date | Nov 25, 1985 |
| Grant date | Sep 1, 1987 |
| Priority date | — |
| Expiry date | Nov 25, 2005 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B13/18
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A compact projection lens for projecting an enlargement of an image appearing on a cathode ray tube (CRT) onto the screen. The projection lens has a first lens having a positive optical power and at least one aspheric surface, surface of the first lens that faces the screen being convex, a second lens having bi-convex surfaces and a positive optical power, and a third lens having a negative optical power and an aspheric concave surface facing the second lens. The focal length f.sub.1 of the first lens and the focal length f.sub.2 of the second lens are selected for satisfying a condition of EQU 0.55<f.sub.1 /f.sub.2 <1.2.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.