Patent ID: 8882142

Claim:
A capacitive occupant detection system comprising at least one sensing electrode to be arranged on a bottom side of a seat cushion, a seat heater like structure to be arranged on a top side of said seat cushion, and an evaluation unit operatively coupled to said at least one sensing electrode for determining a value representative of the capacitance between the at least one sensing electrode and the seat heater like structure, wherein said evaluation unit comprises an AC signal source coupled to said seat heater like structure for impinging an AC voltage signal on said seat heater like structure and a transimpedance amplifier coupled to said sensing electrode for converting an AC current flowing into the sensing electrode into an AC output voltage, and wherein said seat heater like structure is a seat heater mat, wherein said seat heater mat is operatively coupled to a DC power source in such a way that, in operation, said DC power source supplies a DC power to the seat heater mat via power amplifiers and wherein said AC voltage signal of said AC signal source is coupled to an input of said power amplifiers.