| 摘要 |
<p>This device is for adjusting light for each of N (integer equal to or greater than 2) sets of lighting loads (3), and is equipped with: switching circuits (4) that are connected in series between an alternating-current source and the respective lighting loads that belong to the N sets of lighting loads (3); and a time-division control circuit (5) that individually controls an effective voltage to be supplied to each lighting load that belongs to the N sets of lighting loads (3) by adjusting the periods during which the switching circuits (4) are kept on. The time-division control circuit (5) is equipped with: a zero-cross detection unit (11) that detects a zero-cross point, at which the voltage of the alternating-current source becomes zero, and generates a zero-cross signal having a value that changes at the zero-cross point; an oscillator (13) that generates an oscillation signal having a frequency equal to, or an integer multiple of, that of the alternating-current source; a reference point determination unit (14) that measures a phase difference between the zero-cross signal and the oscillation signal every time the zero-cross signal is generated and determines a common reference point that defines timing for turning the switching circuits (4) ON or OFF on the basis of the measured value; and a time-division control signal generation unit (17) that transmits an ON/OFF signal for turning each switching circuit (4) ON or OFF to each switching circuit (4) at timing that is defined for each of the N sets of switching circuits (4) on the basis of the reference point and the effective voltage to be supplied to the lighting load (3).</p> |
