| 摘要 |
PURPOSE:To shorten the time necessary for the initial stabilization of the supply of a current to a gas detection element, by continuously raising the voltage applied to the heater additionally provided to the gas detection element in response to the lowering in the resistance of the element accompanied by the rising in the detected concn. of gas. CONSTITUTION:When the resistance of a gas detection element RS is lowered, the divided voltage outputs of resistors R2, R3 increase and the output of an adder OP1 increases corresponding to the increment and the comparing output of a comparator OP2 also increases. Therefore, the base current of a transistor TRQ2 increases and the collector current thereof also increases with the increase of said base current. As a result, the base current of TRQ1 increases and the collector current thereof also increases to raise both terminal voltages of a Heater H. When the resistance value of the element RS is lowered according to the detected concn. of gas on the basis of this mechanism, the voltage applied to the heater H rises. That is, because the voltage applied to the heater H is low at a usual time free from gas to be detected, the temp. of the element is set to a low temp. region. Further, because the voltage applied to the heater H rises with the rising in the detected concn. of the gas to be detected and the temp. of the element is set to a high temp. region, an initial action becomes short.
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