| 摘要 |
PROBLEM TO BE SOLVED: To make a beat caused by the discrepancy between switching frequencies avoidable, by making the switching frequencies of switching elements in first and second power supply voltage generating portions identical to each other. SOLUTION: A first switching element in a primary switching artificial resonance circuit 11 repeats an ON/OFF operation based on a pulse signal PS by a self-excited oscillation. After a rectified voltage AC' is adjusted by the ON/ OFF duty cycle, it is transferred to the secondary side coil of a transformer 12. In a second power supply voltage generating portion CH2, a selection changeover circuit SW1 selects a timing circuit 14 in the case of its ordinary operation to feed the pulse signal PS of the timing circuit 14 to a primary switching circuit 17 via it. A second switching element in the primary switching circuit 17 performs an ON/OFF operation synchronously with the pulse signal PS. |
