Optics: image projectors – Light shield – mask – hood – or diaphragm
Reexamination Certificate
2001-06-13
2003-10-14
Adams, Russell (Department: 2851)
Optics: image projectors
Light shield, mask, hood, or diaphragm
C353S031000, C353S075000
Reexamination Certificate
active
06631997
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a light-source device for illuminating a light valve means, such as DMD, used in a projection type display device.
2. Description of the Related Art
A Digital Micromirror Device, known as DMD (a trademark of Texas Instruments Incorporated), is widely used in the projection type display device. DMD has an array of micron square movable micromirrors of 16 &mgr;m×16 &mgr;m fabricated on a silicon substrate. Each micromirror is stable in one of two positions, wherein a source light directed upon the mirror array will be reflected in one of two directions. In one stable “on” mirror position, light will be reflected to a projection lens and focused on the screen. In the other “off” mirror position, light directed on the mirror will be deflected to a light absorber. Each individual micromirror corresponds to one pixel and collectively forms an image by reflecting the light in two directions.
A light-source device for illuminating the light valve as DMD uses a rod integrator to improves the uniformity of the source light (refer to U.S. Pat. No. 5,634,704 for details).
Each micromirror forms “on” and “off” mirror position by tilting at the angles as small as +10° and −10°. Therefor, if the incident light on the DMD has wide angular distribution, each micromirror can not reflect the light in the accurate direction. As a result, the contrast of the projected image decreases.
It is therefor, a primary object of the invention to provide a light-source device, which is capable of providing a source light having uniform brightness of which incident angle has narrow distribution.
SUMMARY OF THE INVENTION
This object is achieved in accordance with one aspect of the present invention which is a light-source device comprising: a rod integrator having an injection end and an emitting end; a lens unit for collecting a luminous flux emitted from the emitting end; and, a diaphragm. The rod integrator forms a plurality of imaginary light-source points, each of which virtually emits the luminous flux toward the emitting end. The diaphragm is disposed in the vicinity of a plane on which the lens unit forms the images of the imaginary light-source points, and selectively blocks luminous flux emitted from each of the images of the imaginary light-source points.
In another aspect of the present invention is A projection type display device comprising: a rod integrator having an injection end and an emitting end; a lens unit for collecting a luminous flux emitted from the emitting end; a diaphragm; a light valve means disposed in the vicinity of the plane on which the lens unit forms an image of the emitting end; and, a projection means. The rod integrator forms a plurality of imaginary light-source points, each of which virtually emits the luminous flux toward the emitting end. The diaphragm is disposed in the vicinity of a plane on which the images of the imaginary light-source points are formed, and selectively blocks luminous flux emitted from each of the images of the imaginary light-source points.
REFERENCES:
patent: 5634704 (1997-06-01), Shikama et al.
patent: 5765934 (1998-06-01), Okamori et al.
patent: 6139156 (2000-10-01), Okamori et al.
patent: 6322219 (2001-11-01), Okamori et al.
patent: 6377336 (2002-04-01), Shiraishi et al.
patent: 2002/0024636 (2002-02-01), Okamori et al.
Miyata Akihisa
Okamori Shinji
Shikama Shinsuke
Adams Russell
Sever Andrew
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