Projection lens assembly and projection display apparatus
US5539579A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 15, 1994 |
| Grant date | Jul 23, 1996 |
| Priority date | — |
| Expiry date | Nov 15, 2014 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B13/04
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An optical system of a projection display apparatus includes a projection lens assembly having a first lens group having a negative power, a second lens group having a negative power and a third lens group having a positive power, all arranged in this order from a side of a screen. An air space is provided between the first and second lens groups and also between the second and third lens groups. Each air space is longer than the entire length of the second lens group as taken along the optical axis of the assembly. The projection display apparatus has a light source for radiating rays of light including three primary color components, a color separating optical system for separating the radiation into three primary color components, first to third light valves each operable to receive the respective primary color components from the color separating optical system and to form an optical image having an optical characteristic varying as a function of a video signal, a color combining optical system for combining images of light emerging, respectively, from the light valves to provide a composite image. The projection lens assembly receives the image from the combining unit so as to…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.