Color picture projection system with a wavelength-selective reflector for filtering out undesired light from a monochrome picture display source
US4679069A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Jul 13, 1984 |
| Grant date | Jul 7, 1987 |
| Priority date | — |
| Expiry date | Jul 13, 2004 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N9/31
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
In a color picture projection system three monochrome pictures are superimposed to form a color display on a projection screen by means of a chromatic projection lens system in each of three channels. Each channel has a reflector to fold the light path. Since at least one monochrome picture (e.g. the blue picture) includes radiation within a desired band of wavelengths corresponding to its associated color and radiation outside of this desired band, the reflector in this channel is wavelength-selective and reflects only the radiation within the desired band towards the projection screen. The undesired radiation is transmitted through the reflector so that it does not reach the projection screen. Achromatic lenses are therefore not required.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.