| 摘要 |
PROBLEM TO BE SOLVED: To provide a DC power supply in which the conduction width of an AC voltage subjected to phase control can be made constant regardless of voltage variation of an AC power supply.SOLUTION: A DC power supply 1 includes a rectifier circuit 4 for rectifying a phase control voltage output from a phase control dimmer 3 performing phase control of an AC voltage, output circuits 5, 6 for outputting the voltage output from the rectifier circuit 4 as a predetermined DC voltage, and a conduction width detection circuit 40 for detecting the conduction width of a phase control voltage subjected to phase control by the phase control dimmer 3. The output circuits 5, 6 are the DC power supply 1 outputting a predetermined DC voltage depending on the conduction width of a phase control voltage detected by the conduction width detection circuit 40. The conduction width detection circuit 40 has a first threshold voltage for detecting the conduction start time of the phase control voltage, and a second threshold voltage for detecting the conduction end time of the phase control voltage. The second threshold voltage is set lower than the first threshold voltage. |
