| 摘要 |
PROBLEM TO BE SOLVED: To enhance the trouble diagnosing accuracy of a heater when the supply of power to the heater for a sensor is performed by controlling the duty factor. SOLUTION: When collector voltage V does not drop to a level lower than a threshold value V0 and is a value out of a predetermined range, even if the predetermined period TO corresponding to the change delay time of collector voltage V is elapsed at each time when the base signal VB of the transistor of a heater control circuit transfers from off to on, the times becoming out of the predetermined range during a period of ON signals of several times are integrated and, when the integrated time reaches a predetermined time (CO), a heater is judged to be abnormal. |
