| 摘要 |
PROBLEM TO BE SOLVED: To materialize switching of low frequency having a little loss, and restrain noise from being generated, by providing a phase controlling-type switching element for controlling the electrification amount of a heater and a control circuit for it. SOLUTION: A heater 11 connected to a TRIAC 31 and an AC power supply 30 through a relay RL2 to be controlled by a microcomputer 40. The TRIAC 31 uses a zero cross-type and phase controlling-type switching element and controls the conducting angle of the TRIAC 31 by a control signal corresponding to the prescribed conducting angle from the microcomputer 40. The TRIAC 31 is turned on at the point, it is advanced from the zero cross point in one period of AC power supplied from the AC power supply by thefixed phase, and it is turned off at the next zero cross point. As a result, counter electromotive force in off is decreased, high-frequency noise is restrained from being generated, loss is decreased by phase control, and efficient control is enabled. |
