Plural-frequency capacitive occupancy sensing system

US8994385B2 · kind B2 · utility

Assignee

• IEE INTERNATIONAL ELECTRONICS & ENGINEERING S.A. · LU

Inventors

• Michael Virnich · Korlingen, DE
• David Hoyer · Ayl, DE
• Martin Thinnes · Trier, DE
• Michael Puetz · Trier, DE
• Thomas Meyers · Fremont, US

Key dates

• Filing date: Jul 20, 2012
• Grant date: Mar 31, 2015
• Expiry date: Feb 19, 2033

Classification

• Technology area (CPC B): Performing Operations; Transporting
• CPC primary: B60N2210/12
• WIPO field: Transport
• WIPO sector: Mechanical engineering

Abstract

A plural-frequency capacitive occupancy sensing system comprises an antenna electrode and a detection circuit, which is configured to drive the antenna electrode at least with a first and a second signal at a first and a second frequency, respectively, so as to obtain at least a first and a second measurement value indicative of at least one of conductance, susceptance, resistance, reactance and capacitance between the antenna electrode and a reference node, at the first frequency and the second frequency, respectively. The detection circuit compares the capacitance between the antenna electrode and the reference node with a threshold capacitance, the threshold capacitance being derived from a difference between the first and second measurement values and/or the capacitance between the antenna electrode and the reference node being corrected based upon the difference between the measurement values. The detection circuit outputs an occupancy state signal depending on the comparison.