| 摘要 |
A temperature controller compares a temperature detection signal outputted from a temperature sensor with a set temperature preliminary set in a temperature setting circuit. According to a result of the comparison and before a zero-cross point of an AC voltage applied from a commercial AC source to a heating member, a driving circuit of the temperature controller outputs a driving signal to a thyristor to turn ON the thyristor at the zero-cross point. Then the AC voltage is applied to the heating member via the thyristor. Since the determination of turning ON or OFF the thyristor is made before the zero-cross point of the AC voltage applied through the thyristor, the thyristor may surely be turned ON or OFF at the zero-cross point to prevent electromagnetic wave noises from occurring.
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