| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem in the conventional phase control circuit, in which the conduction angle changes by the ripple of power frequency or power voltage and operability is not proper. SOLUTION: Zener diodes ZD1 and ZD2 generate a certain voltage from power voltage. Voltage generated by resistors R2 and R3 is superposed on this voltage, so as to generate a fan-shaped voltage waveform. A capacitor C1 which constitutes an integrating circuit is charged according to this fan- shaped voltage. Positive and negative trigger circuits 2 and 3 generate trigger signals when a reference voltage Vs set by variable resistor VR becomes higher or lower by a certain voltage VT, than the charge voltage Va of the capacitor C1. A TRIAC TRC is controlled for conduction by this trigger signal. |
