| 摘要 |
PURPOSE:To provide a low-cost phase control device capable of setting a phase control finely for a lighting load. CONSTITUTION:A control means 18 counts base clock signals from a base clock generating means 22, and separates each half cycle of an output of an AC power supply 12 into a plural periods. A dim level to which a lighting load is to be dim controlled is set to an input means 19. The control means 18 determines to which period a phase angle corresponding to the set dim level belongs, and detects the period to which the phase angle corresponding to the dim level belongs taking a power supply synchronous signal from a power supply synchronous signal generating means 17 for reference. A counting means 16 responses to a signal for detecting the period to which the phase angle belongs, and counting clock signals from a counting clock generating means 15 are counted in a corresponding number to the phase angle inside the period. When counting is completed, a trigger signal for letting a switching means 13 conductive is generated from a trigger output means 14, and it is stopped in response to the next power supply synchronous signal. |
