Optics: image projectors – Reflector
Patent
1994-07-08
1996-05-28
Dowling, William C.
Optics: image projectors
Reflector
353 69, 348445, G03B 2128
Patent
active
055216587
ABSTRACT:
An optional beam aspect control device enables a video projection system designed for standard aspect ratio (e.g. 4:3), to operate from widescreen-formatted video source material and to project an image with a wide aspect ratio (e.g. 16/9), without loss of picture information or resolution capability and with no risk of source screen burnin due to blank top and bottom regions. A reflector, introduced in the video light beam between the projector and the viewing screen, can be curved in one axis, either manually or by a controllable electric mechanism. The reflector is typically kept flat for operation at the standard aspect ratio (4:3) and then controllably curved to display images in non-standard aspect ratios. The source image outline is always kept optimally registered on the source screen for full screen utilization with no blank top and bottom regions; consequently, when the system operates in a non-standard aspect ratio mode, the source image is forced to operate at an offset aspect ratio. This offset is subsequently corrected optically. Thus in a widescreen mode the source image is compressed horizontally and the projected image, held at full height, is widened optically to the correct size. Optimal source image/screen registration for widescreen operation can be accomplished by adjustment of the vertical scan of the source screen or by a video tape transfer format tradeoff that eliminates top and bottom blank regions by introducing aspect ratio offset error.
REFERENCES:
patent: 5136398 (1992-08-01), Rodriguez-Cavazos et al.
patent: 5280540 (1994-01-01), Addeo et al.
patent: 5386236 (1995-01-01), Hong
patent: 5386252 (1995-01-01), Oku
patent: 5428454 (1995-06-01), Kimura et al.
Dowling William C.
McTaggart J. E.
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