Patent ID: 9356525
Filing Date: 2016-05-31
CPC Classification: G03G,H02M,Y02B

Claim Text:
1. A power supply device comprising: a transformer having a primary winding and an auxiliary winding on a primary side of the transformer and a secondary winding on a secondary side of the transformer, the auxiliary winding having a winding direction different from a winding direction of the primary winding; a switching unit that switches current flowing to the primary winding; a detection unit that detects current flowing through the primary winding, and outputs a first voltage according to the current; a secondary side voltage detection unit configured to output a second voltage according to an output voltage output from the secondary winding; a control unit that controls switching operation of the switching unit according to the first voltage and the second voltage, wherein the control unit is configured to be switchable between a normal mode in which the switching unit is switched at a first frequency and a power saving mode in which the switching unit is switched at a second frequency lower than the first frequency; and a correction unit that corrects the first voltage output by the detection unit in a case where an auxiliary winding voltage that is induced in the auxiliary winding is higher than a first predetermined value and that does not correct the first voltage in a case where a voltage induced in the auxiliary winding is less than the first voltage, wherein, in the normal mode, the correction unit corrects the first voltage output from the detection unit and the control unit controls the switching unit according to the corrected first voltage output by the correction unit and the second voltage, and wherein, in the power saving mode, the control unit controls the switching unit at the second frequency according to the first voltage output from the detection unit and not corrected by the correction unit and the second voltage.