| 摘要 |
PURPOSE:To make it possible to continuously correspond to the alteration of an augmentation heater even if the actual resistance of the augmentation heater receives a disturbance by controlling an electric power in order to hold the output resistance value of a power control circuit in a set value based on the respective detected information of a voltage and a current. CONSTITUTION:An interterminal voltage detector 14 is connected between both terminals of the augmentation heater 13 and a current detector 15 is connected to the terminal on one side. A computing element 121, which is constituted of an operational amplifier, etc., generates a difference signal epsilon between a feedback current detected value K.If and a feedback voltage detected value vf/n and the difference signal epsilon is transmitted to a pulse width modulator PWM 122, which controls a switching pulse SP in terms of pulse width corresponding to the difference signal epsilon. Since the power is supplied to the heater 13 by controlling the voltage or the current in order that the heater 13 is always a constant resistance, the temperature of the heater 13 can be kept constant against any disturbance and the deterioration of the heater 13 can be kept the minimum.
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