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Side pincushion modulator circuit with overstress protection

  • US 4,329,729 A
  • Filed: 06/23/1980
  • Issued: 05/11/1982
  • Est. Priority Date: 06/23/1980
  • Status: Expired due to Term
First Claim
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1. A side pincushion correction circuit with overstress protection, comprising:

  • a deflection winding;

    a trace capacitance coupled to said deflection winding for developing a trace voltage;

    first switching means for applying said trace voltage to said deflection winding to generate a deflection trace current in said deflection winding;

    a first retrace capacitance coupled to said deflection winding for generating a deflection retrace current in said deflection winding;

    a modulator inductance;

    a modulator capacitance coupled to said modulator inductance for developing a modulator voltage;

    second switching means for applying said modulator voltage to said modulator inductance to generate a sawtooth modulator current in said modulator inductance;

    a second retrace capacitance coupled to said modulator inductance for generating a retrace current in said modulator inductance;

    a source of operating voltage;

    means including a flyback transformer winding coupled to said source of operating voltage for charging said trace and modulator capacitances;

    controllable shunting means coupled to said modulator capacitance and responsive to bias voltages for developing a shunt current to control said trace and modulator voltages;

    means for applying to said controllable shunting means a vertical rate bias voltage to vary said shunt current at a vertical rate to provide side pincushion correction;

    a source of reference voltage; and

    means for clamping said modulator capacitance to said source of reference voltage to bypass current from said modulator capacitance when the voltage thereacross exceeds a predetermined level.

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