| 摘要 |
An air-fuel sensor (3) comprises an electromotive force sell (3a), an oxygen pump cell (3b), and a heater (3c). A control device (1) comprises: a sensor drive IC (5) to detect an output voltage (a Nernst voltage) of the electromotive force sell (3a) and perform precision control for adjusting a pump current to the oxygen pump cell (3b); and a heater control unit (7) comprising a microcomputer (8) and an output circuit to output a heater drive signal in a PWM signal format to the heater (3c). A period table (17) indicating a precision control period during which the sensor drive IC (5) performs the precision control and a non-precision control period during which the sensor drive IC (5) does not perform the precision control is stored in a ROM (13) of the microcomputer (8). A CPU (11) of the microcomputer (8) determines a timing for reversing the heater drive signal to escape from the precision control period based on the period table (17). |
