| 摘要 |
PROBLEM TO BE SOLVED: To reduce vibration sound generated from a transformer at the time of driving with light loads to reduce power consumption.SOLUTION: An electric power device includes: a transformer 108 in which a primary side and a secondary side are insulated; an FET 107 for turning ON/OFF supply of current to the primary side of the transformer 108; a correction circuit 500 for detecting output in accordance with the current which flows into the primary side; a photocoupler 115 for comparing output voltage from the secondary side with reference voltage to transmit the voltage in accordance with comparison results to the primary side; and a power supply IC 109 for controlling the tuning ON/OFF operation by the FET 107 in accordance with the output from the photocoupler 115. When switching frequency at which the FET 107 is turned ON/OFF is within the range of a predetermined frequency where resonance frequency of the transformer 108 is defined as a center, the power supply IC 109 controls the FET 107 so that the time of the ON state of the FET 107 can be shortened in accordance with the output from the correction circuit 500. |
