| 摘要 |
<P>PROBLEM TO BE SOLVED: To dispense with a current-limiting resistor for reducing a rush current when a direct-current power supply circuit is started, and a switching element for bypassing it to prevent increase in a cost and the overall size of equipment. <P>SOLUTION: When the direct-current power supply circuit 1 of a rush current prevention circuit is started, a gate control circuit 9 carries out switching control. In the switching control, the gate control circuit turns on a first triac 5 each time a supply voltage detected by a first voltage detection circuit 8 drops to a target level after it reaches its peak. This target level is higher by a predetermined level than the terminal voltage of a smoothing capacitor 7 detected by a second voltage detection circuit 10. The gate control circuit keeps on the first triac until the supply voltage is zeroed. When the terminal voltage of the smoothing capacitor 7 raises to a predetermined specified voltage or higher in response to the execution of the switching control, the first triac 5 and a second triac 6 are switched to a continuous on-state. <P>COPYRIGHT: (C)2007,JPO&INPIT |
