Patent ID: 7432484

Claim:
A high frequency heating apparatus which drives a magnetron ( 12 ) by allowing a semiconductor switching element ( 3 , 4 ) to perform a high frequency switching operation using a commercial power supply ( 1 ), said high frequency heating apparatus comprising: input fixing control means ( 19 ) for providing accumulation information based on a variation amount of a current of said commercial power supply ( 1 ) and a reference signal (Ref); ebm-tracking bias means ( 20 ) for providing an bias value on the basis of the voltage of said commercial power supply ( 1 ) and said accumulation information; frequency modulation means ( 15 ) for providing a frequency modulation waveform on the basis of the voltage of said commercial power supply ( 1 ), said frequency modulation waveform being given a bias in accordance with said bias value; driving unit ( 16 , 17 , 18 ) for providing driving signals which drives said semiconductor switching element on the basis of the signal output from said frequency modulation means ( 15 ), wherein said ebm tracking bias means ( 20 ) performs a feedback control by controlling said bias value in accordance with a variation of an oscillation threshold ebm caused by a change in a temperature of said magnetron ( 12 ).