Patent ID: 7952299

Claim:
A control circuit which controls the ON/OFF operation of a switching transistor provided on a path to a primary coil of a transformer of a self-exciting capacitor charging circuit, comprising: a first voltage comparator which compares the voltage drop that occurs at a first resistor provided on a path for a current which flows through the primary coil of the transformer, with a predetermined first threshold voltage; a second voltage comparator which compares the voltage drop that occurs at a second resistor provided on a path for a current which flows through a secondary coil of the transformer, with a predetermined second threshold voltage; a switching control unit which generates a switching signal the level of which is switched according to the output signals of the first and second voltage comparators, and which outputs the switching signal thus generated to a control terminal of the switching transistor; and an automatic restart circuit configured such that, after a predetermined period of time elapses after the switching signal is switched to a level which turns off the switching transistor, the switching signal is forcibly switched to a level which turns on the switching transistor.