| 摘要 |
<p>PROBLEM TO BE SOLVED: To avoid the influence of the fluctuation of voltage of the utility power. SOLUTION: A triac Q1 in the load driver 4 is interposed between the utility power AC and the lighting load L, and is turned on by the microcomputer 8 in the controller unit 1 through a photo coupler PC. In the controller unit 1 a zero-crossing detector 9 is provided for detecting the zero-crossing point of the power supply voltage of the utility power AC. The microcomputer 8 in the controller unit 1 gradually precipitate the timing of turning on the triac Q1 from the zero-crossing point detected at the zero-cross detector 9 to turn fade-in on, when the on-switch SW1 or the dimmer switch SW3 is operated. Thus the turn-on timing of the triac Q1 is determined by the microcomputer 8 based on the zero-crossing point of the power supply voltage, so that the fluctuation of the power supply voltage is liable not to be influenced.</p> |
