Optics: image projectors – Light shield – mask – hood – or diaphragm
Patent
1995-06-05
1997-03-04
Dowling, William
Optics: image projectors
Light shield, mask, hood, or diaphragm
348781, G03B 2114
Patent
active
056072163
ABSTRACT:
A projection display apparatus comprises an image source having a rectangular image-displaying surface; a projecting lens assembly for magnifying and projecting the image onto a screen; and light-obstructing plate disposed in the vicinity of the nearest lens element of the projecting lens assembly to the image source. The light-obstructing plate is disposed in such a position that 0.1.ltoreq.R.sub.1 /R.sub.2 .ltoreq.0.8 where R.sub.1 is a radius of optical-axis light which is emitted toward the screen from a central point on the image-displaying surface through which the optical axis of the projecting lens assembly passes, and R.sub.2 is a radius of effective light which is emitted toward the screen from the image-displaying surface. The light-obstructing plate is provided with protrusions which are disposed at positions at a same distance from a first, or a second reference line on the light-obstructing plate so as to obstruct several pairs of flare beams, which are included in peripheral light emitted from the vicinity of four corners of the image-displaying surface and are traveling towards positions at a same distance from the first or the second reference line.
REFERENCES:
patent: 4810076 (1989-03-01), Murao et al.
patent: 4933599 (1990-06-01), Fukuda
patent: 5210645 (1993-05-01), Orino et al.
patent: 5371559 (1994-12-01), San-Nohe et al.
patent: 5379083 (1995-01-01), Tomita
patent: 5519518 (1996-05-01), Watanabe et al.
Kaneko Toshihide
Toide Eiichi
Dowling William
Mitsubishi Denki & Kabushiki Kaisha
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