Electrostatic occupant detecting apparatus and method of adjusting electrostatic occupant detecting apparatus

A method of adjusting an electrostatic occupant detecting apparatus, the electrostatic occupant detecting apparatus including an electrostatic sensor and a sensor property measuring device, the electrostatic sensor including a first electrode, a second electrode, and a guard electrode, the first electrode and the second electrode disposed at a seating part of a seat of a vehicle and being spaced from each other, the first electrode and the second electrode located on an opposite side of the guard electrode from a seat frame electrically coupled with a vehicle ground, the guard electrode being spaced from the first electrode and the second electrode and opposing the first electrode and the second electrode, the sensor property measuring device including a signal source and a resistor, the signal source configured to apply an alternating-current voltage signal to the electrostatic sensor, the resistor configured to generate a potential difference in accordance with an impedance of the electrostatic sensor when the signal source applies the alternating-current voltage signal to the electrostatic sensor, the method comprising:

• coupling a plurality of load circuits instead of the electrostatic sensor with the sensor property measuring device through a switch, each of the plurality of load circuits including a parallel circuit of a resistor and a capacitor, each of the plurality of load circuits having a different measured value depending on the parallel circuit, the plurality of load circuits including a first group of load circuits and a second group of load circuits, the second group of load circuits having a load higher than the first group of load circuits;
• controlling the switch so that the first group of load circuits is coupled with the sensor property measuring device, applying the alternating-current voltage signal from the signal source of the sensor property measuring device to the first group of load circuits, measuring a potential difference generating at the resistor of the sensor property measuring device, and storing a measured potential difference as a first measured value;
• controlling the switch so that the second group of load circuits is coupled with the sensor property measuring device, applying the alternating-current voltage signal from the signal source to the second group of load circuits, measuring a potential difference generating at the resistor of the sensor property measuring device, and storing a measured potential difference as a second measured value;
• and
• calculating a measured sensitivity from the first measured value and the second measured value, calculating a sensitivity adjusting value from the measured sensitivity and an ideal sensitivity, and storing the sensitivity adjusting value in a nonvolatile memory.