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Video signal processor for controlling the brightness and contrast of a display device

  • US 5,504,538 A
  • Filed: 12/27/1994
  • Issued: 04/02/1996
  • Est. Priority Date: 09/01/1992
  • Status: Expired due to Fees
First Claim
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1. A video signal processor for receiving an input video signal and for controlling a display device having a first electrode and a second electrode, comprising:

  • generation means for generating, based on a brightness control signal, a brightness reference signal in a range from a positive voltage level to a negative voltage level including a zero voltage level;

    adding means for adding the brightness reference signal, which is any one of a positive voltage level, a zero voltage level or a negative voltage level, to a pedestal level in a vertical blanking period of the input video signal, said added brightness reference signal being applied to said first electrode;

    detection means for detecting a current of said added brightness reference signal, and for producing a current level signal commensurate with the detected current;

    DC potential setting means for setting a DC potential based on said current level signal;

    voltage supplying means for supplying a control voltage to said second electrode; and

    clamping means for clamping a peak of said control voltage to a voltage determined by said DC potential setting means such that a voltage difference between a peak of said added brightness reference signal and said peak of the control voltage is maintained constant.

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