| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a dimming system which can assure constant illuminance by preventing flicker or brightness fluctuation in dimming regardless of fluctuation in commercial frequency and difference in commercial frequency band. SOLUTION: This dimming system is constituted to dim an illumination load 8 driven by a commercial power source 9 by phase control using a phase control element 7. In this case, provided are a zero cross circuit 1 for generating zero cross signals being synchronized with a commercial frequency, a frequency multiplication circuit 2 for generating clock signals having any times frequency of the zero cross signals, a counter 3 for accepting the clock and zero cross signals to count the number of the clock signals between the zero cross signals adjacent to each other, a trigger position setting circuit 4 for presetting a setting value to represent a position where trigger signals generate, and a trigger signal output circuit 6 for outputting the trigger signals when this setting value coincides with a count value of the counter 3, to control the phase control element 7 with the trigger signal.</p> |
