Dual function capacitive sensor for seat occupant detection

摘要

A dual function capacitive occupant detection sensor includes a capacitive load cell disposed below a seat cushion, an electric field emitter disposed above the seat cushion and a capacitance-responsive control circuit. The control circuit determines a seated weight of an occupant based on the load cell capacitance, and a coupling of the electric field through an occupant based on the capacitance between the electric field emitter and the vehicle ground. The measured seated weight and electric field coupling parameters are logically combined to detect an occupant and to distinguish between a normally seated occupant and a cinched down infant or child seat of similar apparent weight.