Projection system with a cathode ray tube and a lens
US4933599A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 30, 1988 |
| Grant date | Jun 12, 1990 |
| Priority date | — |
| Expiry date | Nov 30, 2008 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B13/18
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A projection system comprising from the image end a screen, a lens in which a core portion including the lens axis accomplishes a convergence function and in which a peripheral portion including a lens edge thereof accomplishes the divergence function, a convex lens element, a concave lens element and a CRT having a face glass whose inner surface is coated with a phosphor and is so curved to form a fourth lens element with a curvature center within a core portion including the lens axis is disposed on the screen side of the projection system, the curvature radius of each part of the core portion of the fourth lens increasing thereof in accordance with increments of the semi-aperture distance of each part from the lens axis.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.