Capacitive proximity switch

US7205777B2 · kind B2 · utility

Assignees

• IFM Electronic GmbH · US
• Huf Hülsbeck & Fürst GmbH & Co. KG · DE

Inventors

• Joerg Schulz · Lustenau, AT
• Gerhard Heilig · Weingarten, DE
• Heidrun Richter · Wertingen, DE
• Bernd Steegmann · Heiligenhaus, DE
• Martin Witte · Ahaus, DE
• Gianni Uselli · Velbert, DE

Key dates

• Filing date: Aug 9, 2004
• Grant date: Apr 17, 2007
• Expiry date: Sep 3, 2025

Classification

• Technology area (CPC H): Electricity
• CPC primary: H03K2217/960715
• WIPO field: Civil engineering
• WIPO sector: Other fields

Abstract

A capacitive proximity switch for detecting the change in the capacitance relative to a setpoint capacitance by the approach or retreat of an object in the sensitive area of a proximity switch, especially for use in the door handle of a motor vehicle, provides reliable error detection and error suppression at a fundamentally high sensitivity of the capacitive proximity switch by utilizing an evaluation unit that evaluates a measured value of the change in capacitance over time and depending on the time behavior of the measured value activates changes the operating threshold from a first threshold (which can be caused by a false object coming into or out of the sensitive area of the proximity switch) to a higher second threshold which can be reached only at a relatively greater change in capacitance caused by a target object coming into or out of the sensitive area of the proximity switch.