Gas concentration detecting apparatus

A gas concentration detecting apparatus comprising:

• a gas sensor having at least one sensor cell each provided with a pair of electrodes on a solid electrolyte, and a heater generating heat when being energized to heat the at least one sensor cell;
• and
• a sensor control apparatus configured to control operation of the at least one sensor cell and the heater,
• wherein
• the sensor control apparatus comprises:
• a sensor detector configured to detect a sensor current or a sensor voltage produced in the at least one sensor cell;
• a temperature detector configured to detect a temperature of the at least one sensor cell;
• a heater control unit configured to adjust an application voltage applied to the heater;
• and
• a computer comprising:
• a change rate calculation unit configured to calculate at least either a change rate of the application voltage applied to the heater or a change rate of a heater current flowing through the heater when the heater control unit maintains the temperature detected by the temperature detector to be a target temperature;
• and
• a calibration outputting unit configured to utilize the change rate calculated by the change rate calculation unit to calibrate a sensor output which is the sensor current or the sensor voltage detected by the sensor detector, thereby calculating a sensor calibration output of the gas sensor.