High efficiency optical tank for three color liquid crystal light valve image projection with color selective prepolarization and single projection lens
US4425028A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 28, 1981 |
| Grant date | Jan 10, 1984 |
| Priority date | — |
| Expiry date | Dec 28, 2001 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N9/3167
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A full color high contrast image projection system with oil coupled dichroics and a single projection lens is disclosed. The invention includes a unitary optical tank in which a prepolarizer and dichroic separators are mounted in fixed alignment relative to a main polarizing prism. The prepolarizer acts on the incident light from a source to polarize the green light and reflect the S component out of the system. The red and blue components are transmitted unchanged. The main polarizer is mounted at a 90.degree. twist relative to the prepolarizer so that it reflects the green light to a first light valve via a first dichroic separator. The polarized red and blue components are transmitted to second and third light valves via a second dichroic separator. The light valves modulate the polarization state of incident light before returning it to the second beamsplitter. The second beamsplitter then recombines the individual beams into a single output beam. This beam is projected by a telecentric projection lens to provide a full color high contrast image.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.