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Automatic convergence and gray scale correction for television _receivers and projection television systems

  • US 4,485,394 A
  • Filed: 09/27/1982
  • Issued: 11/27/1984
  • Est. Priority Date: 09/27/1982
  • Status: Expired due to Term
First Claim
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1. A system operative during normal viewing for the automatic correction of convergence and gray scale in color television receivers employing three cathode ray beams comprising:

  • at least one light sensor permanently positioned to detect a spot of light from a predetermined location on the display surface of said color television receiver;

    means for blanking a different two of the three cathode ray beams on successive scans of the display surface in the vicinity of said light sensor;

    processing means connected to receive the output of said light sensor for producing the timing characteristics indicative of the time required for the scan of the non-blanked cathode ray beam to reach said predetermined location of the light sensor;

    first comparing means connected to said processing means for comparing the timing characteristics of the light sensor output for each said successive scan with predetermined timing characteristics to develop position error signals for each of said cathode ray beams; and

    first correction means responsive to said position error signals for developing vertical and horizontal correction signals to correct the convergence of each of said three cathode ray beams.

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