Capacitive sensor for measurement of pressure and force and proximity switches and containers liquid level measurement

摘要

The control circuit (3) controls the measuring and the reference capacitors (1,2). An evaluation circuit (4) evaluates the capacitances of the two capacitors (1,2) and delivers an esp. pressure dependent sensor signal. The control circuit (3) has a constant current source (5) for the simultaneous charging of the two capacitors (1,2). The control circuit (3) has a regulator (6) regulating the voltage difference between the measuring capacitor (1) and the reference capacitor (2) to a desired value 0 volt as a regulating variable. The current is adjusted either in the measuring capacitor (1) or in the reference capacitor (2) as an adjustment variable.