| 摘要 |
PROBLEM TO BE SOLVED: To realize reducing of a high frequency component of input current of a power supply line by using a main switch element having a low voltage resistance and to deal with a short power interruption of a power supply line. SOLUTION: An input AC voltage is applied to the primary winding of an insulating transformer. The switch element turns on, off the input AC voltage. A first rectifying/smoothing means rectifies and smoothes the voltage induced in the secondary winding of the insulating transformer and outputs an intermediate voltage. A detecting circuit detects the intermediate voltage and outputs a detection signal. A control circuit (46) receives the detection signal via a photocoupler, and controls on, off of the switch element. The intermediate voltage is applied to the primary winding of a main transformer. The main switch element turns on, off the intermediate voltage. A second rectifying/smoothing means rectifies and smoothes an AC voltage output from the secondary winding of the main transformer, and outputs a secondary side output voltage. A control circuit (50) monitors the output state of a second rectifying/smoothing circuit, and controls on, off the main switch element. COPYRIGHT: (C)2005,JPO&NCIPI
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