Optical overhead projector for electronic images
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United States of America Patent
Stats
-
Nov 9, 1993
Grant Date -
N/A
app pub date -
Jan 25, 1993
filing date -
Jan 25, 1993
priority date (Note) -
Expired
status (Latency Note)
Importance
Abstract
A relatively small liquid-crystal display (LCD) device located well above the fresnel stage of an overhead projector produces large, sharp images with full color and motion. A focus-correcting lens moves with the overhead projector's optical head to maintain proper projection-focus and magnification. Spectrally-selective filters are interposed between the LCD device and fresnel stage to avoid LCD deterioration. A fan-actuated shutter or electrically-actuated shutter optionally provide still further protection. Optical collimation methods are employed to attain a large depth-of-field and image brightness.
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Cited Art Landscape
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