| 摘要 |
PROBLEM TO BE SOLVED: To provide a dimmer which restrains a fault from occurring when an inductive load is connected by mistake.SOLUTION: A dimmer D comprises: a switching circuit 1 including a pair of switching elements Q1 and Q2 which are connected in series facing oppositely each other within a current loop in which a current from a commercial AC power supply returns via an illuminator to the commercial AC power supply; a charge/discharge circuit 2 which repeats charging to each gate of the pair of switching elements and discharging therefrom with the timing corresponding to an operation alternately for the pair of switching elements; a surge voltage detection circuit 3 which detects a surge voltage developing between opposite ends of the switching circuit and, following the occurrence of the surge voltage, generates a charge inhibition signal which remains active for a designated period longer than the cycle of AC power; a charge inhibition circuit 4 which disables the gate from being charged by the charge/discharge circuit for a period from when a charge inhibition signal is input until when the charge inhibition signal remains active; and a surge voltage absorption element 5, connected in parallel with the switching circuit, which absorbs a surge voltage developing between the opposite ends of the switching circuit. |
