Patent ID: 7545133

Claim:
A power supply apparatus including a rectifier diode and a choke coil whose first ends are connected to each other, a first switch element whose first end is connected to a node of the rectifier diode and the choke coil through a resonance coil, a first diode connected in parallel to the first switch element, a series circuit including a first capacitor and a second switch element, the series circuit being connected in parallel to a series circuit including the resonance coil and the rectifier diode, and a second diode connected in parallel to the second switch element, wherein each of the first switch element, the second switch element, and the rectifier diode has a parallel capacitance, between terminals thereof, the power supply apparatus further comprising: a first resistor connected in parallel to the first capacitor; and a third diode connected in series with the first resistor: wherein said third diode is connected with the cathode thereof connected to the second switch element, such that when a positive voltage is present at the end of the first capacitor connected to the second switch element, said positive voltage discharges through the second switch element and does not discharge through said first resistor, and when a positive voltage is present at the opposite end of the first capacitor. said positive voltage discharges through the first resistor and the third diode.