| 摘要 |
PROBLEM TO BE SOLVED: To reduce sound generated from a transformer while reducing a switching loss in a power unit.SOLUTION: The power unit comprises: a transformer 704 including a primary coil 705, a secondary coil 706 and an auxiliary coil 707 wound around a core; an FET 708 for supplying or cutting off a current that flows to the primary coil 705 of the transformer 704; and an IC 710 which controls a switching operation by applying a pulse signal to the FET 708. The power unit can be switched between a normal operation mode and a burst mode during which a period to stop the switching operation of the FET 708 is longer than the normal operation mode and power lower than the normal operation mode is consumed. While the switching operation by the FET 708 is stopped, a pulse signal of at least one wave is applied to the FET 708 in predetermined timing. |
