Patent ID: 8253082

Claim:
A magnetron driving power source comprising: a magnetron for supplying a microwave; a high voltage transformer for supplying a high voltage to said magnetron; a switching part for driving said high voltage transformer at a high frequency; a sensor for transmitting a sensor signal indicative of a current through a primary side of said high voltage transformer; a first control part for giving a drive signal to said switching part; a second control part for issuing an output command to said first control part for comparison by said first control part to said sensor signal, wherein said drive signal transmitted by said first control part is determined based on a result of said comparison of said sensor signal to said output command; and a third control part for transmitting a correction signal to said first control part for correcting the output command to be compared to said sensor signal in response to a decrease in an oscillation threshold value of said magnetron; wherein said first control part is adapted to generate the drive signal by comparing the sensor signal to a reference signal which is a control element of said third control part or the output command, and performs a power down control by using the control element of said third control part as reference signal when the control element of said third control part is lower than the output command; and wherein said control signal transmitted by said third control part is proportional to a collector-emitter voltage in a switching element of said switching part.