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High frequency heating apparatus

  • US 5,286,938 A
  • Filed: 06/17/1991
  • Issued: 02/15/1994
  • Est. Priority Date: 07/24/1990
  • Status: Expired due to Term
First Claim
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1. A high frequency heating apparatus comprising:

  • a) an inverter circuit having a switching element and converting an ac power supply to a high frequency power supply by controlling "on" and "off" periods of the switching element;

    b) a magnetron driven by the inverter circuit;

    c) a control circuit including a counter cumulatively counting an energization period of time and a deenergization period of time of the magnetron, the control circuit generating a signal to control an on-off operation of the switching element of the inverter circuit; and

    d) a drive circuit driving the switching element in response to the signal from the control circuit;

    wherein the control circuit further includes first means for compensating a count-up quantity of the counter per counting operation in accordance with the heating power from the magnetron, second means for compensating the "on" period of the switching element based on a count valve of the counter so that an input power to the inverter circuit is rendered constant, and third means for causing the counter to start the counting operation from an initial value thereof when a first high frequency heating operation is initiated after the power supply is put to work.

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