Dielectric detecting device

Abstract

A dielectric detecting device includes an earth electrode and a sensor electrode opposed to the earth electrode which constitute a capacitor whose capacitance is varied with an existence of a dielectric object therebetween. A detecting device is provided for detecting a change in the capacitance of the capacitor and a capacitance of a circuit in the dielectric detecting device. The detecting device includes an input signal processing device disposed between an output side of the detecting device and an input side of the sensor electrode, a switching device disposed between the input signal processing device and the sensor electrode, and a judging device for judging whether the dielectric object exists or not on the basis of an output of the detecting device and judging whether an error has occurred at one or more of the earth electrode, the sensor electrode, the detecting device and input signal processing device on the basis of capacitances when the switching device is in its on and off conditions.

Dependencies are inferred from the claim text.