Capacitive sensing system configured for using heating element as antenna electrode

US9132850B2 · 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
• Laurent Lamesch · Reichlange, LU

Key dates

• Filing date: Sep 20, 2012
• Grant date: Sep 15, 2015
• Expiry date: Jun 27, 2033

Classification

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

Abstract

A capacitive sensing system for a heating element comprises a capacitive detector connectable to the heating element and a common mode choke for connecting the heating element with a heating current supply. The detector drives an alternating current into the heating element and produces an output depending on the capacitive load, which the alternating current is subject to. Depending on the object sensed, the load varies in a range between a minimum and a maximum value. The choke represents an inductive load in parallel of the capacitive load. The capacitive load and the inductive load contribute to a complex impedance dominated by the inductive load. A compensation capacitor arranged parallel to the choke represents an additional capacitive load also contributing to the complex impedance. The compensation capacitor is dimensioned such that the sum of additional capacitive load and maximum value amounts to at least 50% of the inductive load.