Evaluation circuit for a capacitive sensor

US5172065A · kind A · utility

Assignee

• VDO Adolf Schindling AG · DE

Inventor

• Werner Wallrafen · Schwalbach, DE

Key dates

• Filing date: Nov 30, 1990
• Grant date: Dec 15, 1992
• Expiry date: Nov 30, 2010

Classification

• Technology area (CPC B): Performing Operations; Transporting
• CPC primary: B60S1/0825
• WIPO field: Transport
• WIPO sector: Mechanical engineering

Abstract

In an evaluation circuit for a capacitive sensor, the capacitive sensor and a capacitor form a capacitive voltage divider, the end terminals of which can be fed with opposite-phase alternating voltages of the same frequency. The junction point between the capacitor and the capacitive sensor is connected, together with a tap of a voltage source of high internal resistance, to the input of an impedeance transformer. The output of the impedance transformer is connected to a synchronous demodulator to which at least one phase of the alternating voltage is fed.