Capacitive occupant sensor for a vehicle seat

摘要

A capacitive occupant sensor for a seat has a dielectric in the form of a fluid-filled elastomeric bladder, and the sensor includes a primary region that is subjected to occupant force and a secondary region that is shielded from occupant force. The secondary region includes an appendage of the bladder that is disposed beneath a back cushion of the seat, either in a cavity of the seat cushion or below a frame element that supports the seat cushion. A spring clamp normally biases fluid out of the appendage, but occupant-related force applied over a broad area of the seat produces a flow of bladder fluid into the appendage against the bias force of the spring clamp. A pair of auxiliary conductor plates is oppositely disposed about the bladder appendage, and the capacitance between the auxiliary conductor plates is measured as an indication of fluid pressure in the bladder.