| 摘要 |
<p>PURPOSE:To prevent a bad influence on the AC electric power source, by generating the pattern of an odd bit for controlling the electrification in accordance with a temperature level of the temperature variation, and executing the zero cross switching by said pattern. CONSTITUTION:The output of the temperature detector TH is converted by the AD converter ADC, and by its bit pattern, the temperature level is discriminated. In accordance with this temperature level, the pattern generator PG generates the pattern of an odd bit. This pattern is provided to the shift register SR, and is converted to the pulse of time constant by a synchronizing signal which has synchronized with the period of the supply voltage from the synchronizing signal generator ZCD. In accordance with this pulse, the zero switching means PT is operated, and temperature of the heater H is controlled. In this way, the polarity of power supply is made not to be partial to one side, and a bad influence on the AC electric power source can be prevented.</p> |
