| 摘要 |
A light-dimming device (10) includes a switch (3) including a switching device (7), a controller (4), and a power supply module (5). The power supply module (5) includes a capacitor (14) to be charged by a constant voltage circuit (13). The controller (4) includes a driver circuit (8), a zero-cross detection circuit (9), a detecting circuit (21), and a control circuit (11), and receive electric power from the capacitor (14). The driver circuit (8) drives the switching device (7) in accordance with a PWM signal (S1). The control circuit (11) starts generation of a pulse, to be contained in the PWM signal (S1), for turning on the switching device (7) after the zero-cross detection circuit (9) detects zero-cross and also a voltage (V2) across the capacitor (14) is threshold or more. |
