| 摘要 |
PURPOSE:To enable to perform a heating by an efficient heater, by a method wherein an owygen partial pressure sensing part, consisting of Nb2 or CeO2film, an electrode, and a catalyst, is mounted to one surface of both surfaces of an insulating substrate, and a heater is attached to other surface or the same surface. CONSTITUTION:Temperature is detected from a resistance value of a heater using a Wheatstone bridge circuit, and a constant-temperature heating control circuit, applying a power for heating, is attached. A heater 3 is inserted in the middle of one side CA of the bridge. A voltage is applied between terminals B and C of the bridge via a transistor 6 for controlling a power from a constant-voltage source 5. and an unblanced voltage between terminals C and D of the bridge is detected and amplified by a differential amplifier 7 to apply it to the base of the transistor 6. A rectifier 8 is employed so that breakdown is prevented from occurring between the collector bases of the transistor 6. When a product of a resistance 9 and a resistance of a potentiometer 10 becomes approximately equivalent to that of a resistance 11 and the resistance of the heater 3, the unbalanced voltage. of the bridge is brought to approximately zero, a constant voltage is applied to the heater, and a sensor temperature is also brought to a balance. |
