Patent ID: 8354936

Claim:
A capacitive passenger detector for a vehicle comprising: a capacitive sensor including a main electrode, a sub electrode and a guard electrode, wherein the main electrode and the sub electrode are separated apart from each other, and disposed in a seat of a vehicle, and wherein the guard electrode is disposed between the main electrode and a body of the vehicle, and separated apart from the main electrode; a sensor characteristic measurement unit for applying an alternating voltage signal to the main electrode, the sub electrode and the guard electrode selectively or totally and for converting a current generated in the main electrode, the sub electrode and the guard electrode to a voltage, respectively; and a controller, wherein the controller defines a current flowing through the guard electrode to be a reference current when a voltage of the main electrode and a voltage of the guard electrode have a same potential, wherein the controller defines a current flowing direction of the current flowing through the guard electrode to be a negative direction when the voltage of the main electrode is higher than the voltage of the guard electrode, wherein the controller defines the current flowing direction of the current flowing through the guard electrode to be a positive direction when the voltage of the main electrode is lower than the voltage of the guard electrode, and wherein the controller corrects the voltage of the main electrode based on the current flowing through the guard electrode so that a corrected voltage of the main electrode is set to be a passenger determination data.