| 摘要 |
PURPOSE: To improve the power factor of the whole of a power saving circuit, by providing a power circuit with a bidirectional switching means for applying selectively positive or negative current to its load, and by providing control circuits for applying the currents to the load at predetermined timings. CONSTITUTION: A bidirectional switch 5a comprises a FET element 10 connected to DC terminals 11, 12 of a rectification bridge circuit with diodes 13-16, and a load 4 is connected with its AC terminal 17. The control of a gate 21 of the FET element 10 is performed by a main driving portion 52. The control circuits of a power saving circuit 40 receive respectively their AC power supply feedings from a multi-secondary voltage transformer 7 provided between a line terminal 1 and a neutral-point terminal 2, converting its respective secondary AC voltages into floating DC power supply voltages by a regulator 48, etc. Also, the gate control signal of the FET 10 is generated using these control circuits every half cycle of the AC power supply voltage to feed it to the main driving portion 52 via a photo-coupler 51 when triggering a main timer 50. As a result, the foregoing switch 5a applies a current to the load 4 during a predetermined initial term of each half cycle of the AC power supply voltage. |
