Patent ID: 7304869

Claim:
An inverter power source control circuit for a high frequency heating apparatus, which is an inverter power source circuit for supplying an electric power to the high frequency heating apparatus by rectifying an alternating current output from an alternating current source to a direct current output and rectifying the direct current output to a desired alternating current output by applying a drive signal, based on a start signal, to a switching element, which circuit comprises: an electric power source abnormality detecting circuit including a start abnormality detector for detecting an abnormal start signal, a temperature abnormality detector for detecting an abnormal temperature, a voltage abnormality detector for detecting an abnormal voltage present in the drive signal to be applied to the switching element, and a current abnormality detector for detecting an abnormal input current while retaining a detecting state; an inverter oscillation control circuit operable in response to a abnormality detection signal fed from at least one of those abnormality detectors to output an abnormality control signal to the switching element to halt oscillation of the inverter power source, thereby protecting from an abnormality occurring in the power source; and a latch inhibiting circuit provided in at least one of the start abnormality detector, the temperature abnormality detector and the voltage abnormality detector for inhibiting retention of the detecting state of the abnormality detector whereby the current abnormality detector is inhibited from detecting the abnormal input current based on a halt of the oscillation brought about by the detection of the abnormality, thereby allowing an automatic resetting to be accomplished upon removal of the abnormality without causing the oscillation to halt as a result of the current abnormality detector detecting the presence of the abnormality.