Projection lens for projection television
US4620773A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 13, 1983 |
| Grant date | Nov 4, 1986 |
| Priority date | — |
| Expiry date | May 13, 2003 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N5/7408
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A projection lens for magnifying an image displayed on a cathode-ray tube and projecting the magnified image on a projection screen comprises a first lens having a substantially plano surface opposite to the cathode-ray tube and a concave surface, a second lens which is convex meniscus lens having a concave surface opposite to the concave surface of the first lens, a third lens having a strongest positive refracting power and at one convex surface, and a fourth lens spaced apart by a predetermined distance from the third lens having at least one convex surface. The first to fourth lenses are arranged in the above order from the side of the cathode-ray tube, and the predetermined distance between the third and fourth lenses is large enough to permit interposition of a plano reflecting mirror therebetween.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.