Patent ID: 7545154

Claim:
A sensor using a capacitive measuring principle for detecting an approaching dielectric medium, said sensor being adapted for use in an anti-pinching system, and comprising: a capacitor and an evaluation electronic system, wherein a variation of a capacitance of the capacitor caused by the dielectric medium can be measured, and wherein the capacitor can be operated in succession using at least two different frequencies or at least two different pulse duty factors, wherein a group of measurements comprising at least two measurements is performed using a different frequency or different pulse duty factors of the charging voltage for each of said two measurements, and wherein a conclusion about water entering into a field of the capacitor is drawn, if the variation of the capacitance caused by the dielectric medium takes up different values in the case of all the measurements within a group, or a conclusion about a dielectric medium differing from water entering into a field of the capacitor is drawn, if the variation of the capacitance caused by the dielectric medium is substantially constant in the case of all the measurements within a group.