Short focal length video color projector employing dichroic mirror block
US5168351A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 16, 1990 |
| Grant date | Dec 1, 1992 |
| Priority date | — |
| Expiry date | May 16, 2010 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01J29/894
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A video color image projector which includes a block of crossed dichroic mirrors for combining the light rays from image rasters on respective monochrome image display devices and a projection lens for projecting the composite color rays so as to form an enlarged color image on a display screen. Each display device has a faceplace which is convex on the interior surface thereof and having thereon an interference filter in the form of an internal angularly reflecting coating (IARC). Each faceplate is liquid - coupled to a negative power lens element, so that the faceplate, coupling liquid (or gel) and such lens element effectively constitute a single negative power field flattener lens at each entrance side of the dichroic block. The composite color rays at the exit side of the dichroic block are projected on the display screen by an assembly of lens elements which includes at least one optically positive lens element. The focal length of the complete projection lens formed by such assembly and each of the negative field flattener lenses may be from 0.5 to 0.9 times the diagonal D of the image raster on each display device, so that the projector is sufficiently compact to be include…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.