Optics: image projectors – Light shield – mask – hood – or diaphragm
Patent
1994-12-27
1997-01-28
Dowling, William
Optics: image projectors
Light shield, mask, hood, or diaphragm
353101, 349 61, G03B 2114
Patent
active
055972233
ABSTRACT:
A display apparatus includes a light source, a modulating device for modulating light emitted from the light source, a modulating device driving unit for driving the modulating device, a first aperture stop unit arranged between the light source and the modulating device to limit a bundle of rays to be incident on the modulating device from the light source, the first aperture stop unit having an aperture with a variable size, a display screen onto which exit light from the modulating device is projected, a projection optical system for projecting the exit light from the modulating device onto the display screen, a second aperture stop unit arranged between the modulating device and the projection optical system to limit a bundle of rays to be incident on the projection optical system from the modulating device, the second aperture stop unit having an aperture with a variable size, a photosensor for detecting the display luminance on the display screen, and an aperture control unit for controlling the size of the aperture of at least one of the first and second aperture stop units on the basis of a display luminance signal from the photosensor.
REFERENCES:
patent: 5053934 (1991-10-01), Krebs
patent: 5274480 (1993-12-01), Hirai et al.
patent: 5371559 (1994-12-01), San-Nohe et al.
patent: 5379083 (1995-01-01), Tomita
patent: 5473393 (1995-12-01), Manabe
Harada Nozomu
Murakami Seiji
Nakamura Hiroki
Saitoh Yutaka
Sakamoto Tsutomu
Dowling William
Kabushiki Kaisha Toshiba
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