Optical aspect ratio control for video projection
First Claim
1. An optical beam aspect-control device, interposed in a first portion of an optical video beam emanating along a first axis from a source image on a rectangular source screen of a video projector projecting a rectangular image onto a viewing screen, comprising:
- a reflector intercepting the first portion of the video beam and reflecting a second portion thereof in a direction substantially perpendicular to the first portion thereof onto the viewing screen, said reflector being made inherently flat but made flexible along a bending axis thereof; and
reflector-shaping means for controllably bending said reflector along the bending axis to a predetermined curvature;
whereby the aspect ratio, defined as width/height, of the projected image may be varied independent of said video projector.
1 Assignment
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Accused Products
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.
35 Citations
19 Claims
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1. An optical beam aspect-control device, interposed in a first portion of an optical video beam emanating along a first axis from a source image on a rectangular source screen of a video projector projecting a rectangular image onto a viewing screen, comprising:
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a reflector intercepting the first portion of the video beam and reflecting a second portion thereof in a direction substantially perpendicular to the first portion thereof onto the viewing screen, said reflector being made inherently flat but made flexible along a bending axis thereof; and reflector-shaping means for controllably bending said reflector along the bending axis to a predetermined curvature; whereby the aspect ratio, defined as width/height, of the projected image may be varied independent of said video projector. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A video projection system, utilizing a conventional video projector with a rectangular light beam source screen, required to operate in a standard mode providing, on a viewing screen, a projected image having a standard aspect ratio and in at least one widescreen mode providing a projected image having an aspect ratio greater than the standard aspect ratio, comprising:
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an inherently flat reflector intercepting a first portion of a light beam emanating from the source screen and reflecting the first portion of the light beam as a second portion thereof directed substantially perpendicular to the first portion thereof, said reflector being made flexible along a designated bending axis; and a reflector-shaping mechanism operationally coupled to said reflector and enabled to introduce a controllable predetermined amount of curvature in said reflector along the bending axis thereof and thus enable control of the projected image with regard to aspect ratio. - View Dependent Claims (10, 11, 12, 13, 14, 15)
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16. A method of optically modifying the aspect ratio defined as width/height of a projected video image, in a conventional video projection system having a source screen of standard aspect ratio, receiving a video signal formatted for widescreen display at a non-standard aspect ratio, having a projector defining a first portion of an optical beam and a viewing screen receiving a second portion of the optical video beam and displaying therefrom a projected image, comprising the steps of:
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intercepting the first beam portion with a flexible reflector having a substantially planar reflecting surface and oriented so as to redirect the beam to form the second beam portion having a direction substantially perpendicular to the first beam portion; locating the projector, the reflector and the viewing screen relative to each other such as to cause the second beam portion to reach the viewing screen and thereupon display the projected image; and causing the reflecting surface to become shaped with a curvature that acts upon the beam in a manner to shape the projected image to have the intended aspect ratio. - View Dependent Claims (17, 18, 19)
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Specification