Abstract: The purpose of this invention is to sense the presence of a seated occupant in a vehicle such as an automobile, plane, train or bus, or in a room or location where it is desirable to detect if seats are occupied. The occupant presence detection device consists of a single seat-mounted electrode, an oscillator circuit, a bridge circuit, a detection circuit and a circuit for processing the detected signals. The oscillator circuit excites the electrode. If an occupant is present on the seat, additional capacitance from the human body is introduced into the bridge via the electrode. This created differences in the voltage and phase of the waveform in each arm of the bridge circuit which are amplified by a differential amplifier. The signal is then converted to a DC voltage that, when above a predetermined threshold, causes the device to outputs a signal that indicates the presence of an occupant.

Abstract: The purpose of this invention is to sense the presence of a seated occupant in a vehicle such as an automobile, plane, train or bus, or in a room or location where it is desirable to detect if seats are occupied. The occupant presence detection device consists of a single seat-mounted electrode, an oscillator circuit, a bridge circuit, a detection circuit and a circuit for processing the detected signals. The oscillator circuit excites the electrode. If an occupant is present on the seat, additional capacitance from the human body is introduced into the bridge via the electrode. This created differences in the voltage and phase of the waveform in each arm of the bridge circuit which are amplified by a differential amplifier. The signal is then converted to a DC voltage that, when above a predetermined threshold, causes the device to outputs a signal that indicates the presence of an occupant.