OXYGEN CONCENTRATION DETECTOR

摘要

PURPOSE:To prevent the generation of blackening by supplying current to a pump element so as to maintain the voltage generated between the electrodes of a battery element at a specified value and providing such a delay means as to gradually increase the current. CONSTITUTION:The voltage generated between the electrodes 7 and 8 of the element 2 of an oxygen concn. detector constituted of the oxygen pump element 1 and battery element 2 for measuring an oxygen concn. ratio which consist of oxygen ion conductive solid electrolyte materials and are parallel disposed via a spacing part 3 is inputted via a non-inverted amplifier 25 to an operational amplifier 12 and the supply current value to the element 1 is controlled by a current supply circuit 11 in such a manner that the generated voltage is made constant. The current of the element 1 is detected by a resistor 15 and is inputted to an air-fuel ratio control circuit 32. The signal from the circuit 32 is inputted via a digital-to-analog converter 26 and a voltage follower circuit 27 to an integration circuit 28 which gradually increases the current right after the start of the current supply to the element 1.