Projection-type display device having light source means including a first and second concave mirrors
US5142387A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 9, 1991 |
| Grant date | Aug 25, 1992 |
| Priority date | — |
| Expiry date | Apr 9, 2011 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N9/3152
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
The projection-type display device has a light source emitting a parallel luminous flux, a liquid crystal light valve disposed on the luminous flux and outputs a rectangular two-dimensional image to be projected on a screen, and a projection lens magnifying the rectangular two-dimensional image output. The light source has a first concave mirror (parabolic mirror) the reflective surface of which is oriented in the direction of emission of the luminous flux, a lamp laced in front of the first concave mirror, and a second concave mirror (parabolic mirror or spherical mirror), the reflective surface of which is oriented toward the first concave mirror. In the second concave mirror is formed an aperture window, which is a rectangle of substantially similar to that of the liquid crystal light valve and emits a rectangular luminous flux. The beam from the lamp is reflected by the first concave mirror, and one or more times by the second concave mirror, becoming a parallel beam oriented in the direction of the optical axis. The parallel light beam is made into a luminous flux of rectangular cross section by the rectangular aperture window. Accordingly, luminous flux is not blocked wastefu…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.