| 摘要 |
<p>PURPOSE: To provide a low noise type phase controller in which a gentle waveform can be obtained at the time of the rising of the start of energizing in each semi-cycle of an alternating waveform, and a noise can be effectively reduced. CONSTITUTION: Transistors 10A and 10B for switching which can be controlled in a conductive mode and a non-conductive mode by the control of a gate voltage are inverse serially connected, and one transistor for switching is used for the energizing of the positive side area of the alternating waveform, and the other is used for the energizing of the negative side area. Then, in a CPU 12, the gate voltage of each transistor 10A and 10B for switching is risen before a zero cross point in the opposite area of the corresponding energizing area, and fallen after the rising state is held in a time corresponding to an instructed voltage. Thus, inverse phase control can be attained, the gentle alternating waveform can be obtained at the time of the rising of the start of energizing, and a noise can be effectively reduced.</p> |
