| 摘要 |
PURPOSE:To obtain a power controller which has not large voltage noise by always opening or closing the contact of a relay which opens or closes a heater in accordance with zero voltage of an AC power source, thereby elimiating the production of an arc at the relay contact opening or closing time. CONSTITUTION:A power converter is composed of A full-wave rectifying circuit A of diodes D1-D4, a constant-voltage ciruit B, a pulse generator C which generates a pulse with an AC zero voltage upon detection of the zero voltage of the full wave rectification, a relay contact 7-2 connected in series with a heater 2, a temperature detector D, and a relay driving unit E. The unit E is composed of a relay OFF, ON delay pulse generator E-1, E-2, an FF circuit E-3, and a transistor Q2 in which the relay coil 7-1 is connected to the collector, the FF E-3 is operated with the temperature detected by the detector D and the outputs of the generator E-1 or E-2 to conduct or interrupt the transistor Q2, the coil 7-1 is energized or deenergized, the contact 7-2 is opened or closed with the zero voltage of the AC power source, and the heater 2 is controlled. |
