Patent ID: 7206209

Claim:
A switching power source device comprising: a rectifying device connectable to an AC power source; a smoothing capacitor connected to an output of the rectifying device; a transformer having at least first and second primary windings, and a secondary winding; first and second switching elements connected to the output of the rectifying device by way of the first and second primary windings of the transformer respectively; means for rectifying and smoothing a voltage generated to the secondary winding of the transformer; means for outputting error amplified signal for setting a DC current output from the rectifying and smoothing means to a predetermined value; a control device that alternately turns ON and OFF the first and second switching elements based on the error amplified signal and an input voltage from the AC power source; and a first series circuit formed of at least the first primary winding of the transformer, a diode, and the first switching element, and a second series circuit formed of at least the second primary winding of the transformer, another diode, and the second switching element, wherein the first and second series circuits are connected in parallel to form a parallel connection circuit, and the parallel connection circuit being connected to the output of the rectifying device.