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Method and apparatus for calibrating geometrically an optical computer input system

  • US 5,933,132 A
  • Filed: 05/15/1996
  • Issued: 08/03/1999
  • Est. Priority Date: 11/07/1989
  • Status: Expired due to Fees
First Claim
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1. A coordinate correction apparatus comprising:

  • image detection means for perceiving visually a displayed generally rectangularly shaped projected image having keystone distortion;

    hand held auxiliary light means for successively illuminating the corners of the distorted image with spots of high intensity auxiliary control light for facilitating defining the geometric form of the keystone distortion in the projected image;

    said image detection means responsive to said spots of high intensity light only during a calibration mode for generating a signal indicative of the location of the high intensity spots;

    signal processing means responsive to said signal during said calibration mode for determining the geometric center of the geometric form of the keystone distortion defined by the intersection coordinate values of a pair of imaginary lines interconnecting the detected spots of high intensity light;

    distortion orientation calculating means responsive to the determined geometric center for determining quadrant scaling factors to facilitate determining corrected coordinate values for detected spots of high intensity auxiliary control light during a normal mode of operation;

    said signal processing means storing the scaling factors for use during said normal mode of operation to enable said signal processing means to convert subsequently a determined auxiliary light sensing coordinate value relative to another computer generated projected image having substantially the same keystone distortion as said first mentioned projected image;

    said signal processing means using said stored scaling factors for converting the determined auxiliary light sensory coordinate values to absolute coordinate values, said absolute coordinate values being indicative of corresponding coordinate value information defining a fixed location within said another computer generated image.

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