| 摘要 |
PROBLEM TO BE SOLVED: To adequately detect the element resistance without affecting the detection of the gas concentration. SOLUTION: A gas concentration sensor 100 comprises a pump cell 110 for exhausting or pumping oxygen in the detection gas introduced in a chamber, a sensor cell 130 for detecting the concentration of a specified gas composition from the gas passing through the pump cell 110, and a monitor cell 120 for detecting the concentration of the residual oxygen in the chamber. A control circuit 200 detects the current flowing in the sensor cell 130, and sequentially detects the concentration of the specified gas composition from the detected value. The control circuit 200 temporarily switches the voltage or the current applied to the cell other than the sensor cell 130, for example, the monitor cell 120 at a predetermined period, and detects the element impedance (the element resistance) from the change in the voltage or the current in that state. |
