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Drive circuit for a cathode ray tube

  • US 5,604,404 A
  • Filed: 11/07/1995
  • Issued: 02/18/1997
  • Est. Priority Date: 01/21/1993
  • Status: Expired due to Term
First Claim
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1. A drive circuit for a flat cathode ray tube having a cathode electrode, a first grid electrode and a second grid electrode, comprising:

  • a high-voltage generator receiving horizontal drive pulses for generating a first fixed DC voltage supplied to said cathode electrode, a fixed voltage supplied to said second grid electrode of said cathode ray tube, a high voltage supplied to said cathode ray tube, and a second fixed DC voltage;

    a differential amplifier for supplying a video signal for producing a video display on said cathode ray tube;

    means connected to said high-voltage generator and to said differential amplifier for combining said second fixed DC voltage and said video signal and for adjusting said second fixed DC voltage to effect cutoff adjustment and to supply a combined DC voltage and video signal to said first grid electrode of said cathode ray tube, said cutoff adjustment and said fixed voltage supplied to said second grid electrode being mutually independent; and

    a constant-current source for supplying a constant current to said differential amplifier and for switching said differential amplifier to blank said video signal according to a blanking pulse signal,wherein said high-voltage generator includes a secondary coil that operates independently from said differential amplifier to produce a pulsed voltage, said cathode electrode being energized by said first fixed DC voltage and also by said pulsed voltage.

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