| 摘要 |
<p>PROBLEM TO BE SOLVED: To precisely detect a capacitance between a sensor electrode and a work by inputting an output voltage of an oscillation circuit and an output voltage in which an electric current between the sensor electrode and the work is converted to a voltage signal. SOLUTION: A converting circuit 4 mounted close to a sensor electrode 2 converts the electric current, which causes to flow to a capacitance Cx between the sensor electrode and work 1, to a voltage signal. An arithmetic circuit part 5 consists of an oscillation circuit 52 to supply a sinusoidal wave alternating voltage Vs of a constant frequency and an arithmetic circuit 51 to operate an output voltage Vo corresponding to a distance between the sensor electrode 2 and work 1. By this method, the output electric current from the oscillating circuit 52 is shunted to a floating capacity Cf between a cable 3 and ground, the voltage only corresponding to the electric current flowing to the capacitance Cx is detected in the converting circuit 4. Thus, the capacitance Cx between the sensor electrode 2 and work 1 is precisely detected.</p> |
