Projection display apparatus
US5607216A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jun 5, 1995 |
| Grant date | Mar 4, 1997 |
| Priority date | — |
| Expiry date | Jun 5, 2015 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N5/7408
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A projection display apparatus comprises an image source having a rectangular image-displaying surface; a projecting lens assembly for magnifying and projecting the image onto a screen; and light-obstructing plate disposed in the vicinity of the nearest lens element of the projecting lens assembly to the image source. The light-obstructing plate is disposed in such a position that 0.1.ltoreq.R.sub.1 /R.sub.2 .ltoreq.0.8 where R.sub.1 is a radius of optical-axis light which is emitted toward the screen from a central point on the image-displaying surface through which the optical axis of the projecting lens assembly passes, and R.sub.2 is a radius of effective light which is emitted toward the screen from the image-displaying surface. The light-obstructing plate is provided with protrusions which are disposed at positions at a same distance from a first, or a second reference line on the light-obstructing plate so as to obstruct several pairs of flare beams, which are included in peripheral light emitted from the vicinity of four corners of the image-displaying surface and are traveling towards positions at a same distance from the first or the second reference line.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.