| 摘要 |
PROBLEM TO BE SOLVED: To provide an electric power supply in which the fluctuations of load voltage are hardly generated even in the combination of a phase control device. SOLUTION: The triac TR of a light control unit 2 is off in a power-on, and a switching element Q3 of a leakage current bypass circuit 10 is on. In this case, the leakage current which flows to an electric power supply 3 from the capacitor C1 of the light control unit 2 flows off through the leakage current bypass circuit 10, so little voltage is applied on the power terminal of the electric power supply 3. Accordingly all the voltage of a commercial power source 1 is applied on the light control unit 2, and because a phase detection circuit 9 of the light control unit 2 does not become an obstacle in the case of judging the power supply phase, fluctuations of the phase angle where the triac TR becomes on is made to be less, and as a result, the fluctuations of the output voltage become smaller. |
