| 摘要 |
PROBLEM TO BE SOLVED: To control light of an incandescent lamp to an optional optical output, and reduce switching loss and noise when a switching element is turned on. SOLUTION: A control means 2 changes average power supplied to the incandescent lamp L in a unit time and adjusts the optical output of the incandescent lamp L by adjusting a ratio of a time for turning on the switching element SW and a time for turning off the switching element SW on every unit time, wherein an integral multiple of a half period of an output voltage of an alternating current power source AC is the unit time. The control means 2 includes a zero cross detection part 4 for detecting a zero cross point of the output voltage of the alternating current power supply AC, and a pattern control part 5 for controlling on and off of the switching element SW in accordance with an output pattern at a timing synchronizing with the zero cross point detected by the zero cross detection part 4, wherein a time-series pattern of the on and off of the switching element SW in the unit time is prescribed as an output pattern. COPYRIGHT: (C)2007,JPO&INPIT |
