DISTANCE MEASURING EQUIPMENT

摘要

PROBLEM TO BE SOLVED: To measure a thickness of a film or the like or a distance from a conductive substance in a simple manner by changing a distance between a distribution plane of an element having a distribution inductance interacting with the conductive substance such as a metal and a conductive substance opposite thereto in parallel. SOLUTION: When a distance between a surface of an inductor distributed two-dimensionally and a conductive substance 10 decreases, both are electrically coupled to each other. The distance between them is measured from a drop in inductance of the inductor 20 due to counteraction of electromagnetically induced current. A detection circuit constitutes an LC circuit 35 with a concentrated capacitor 30 connected in series with the inductor 20. An output signal form the LC circuit 35 is input via a transistor amplifier 31 to a feedback network 32 and a frequency counter 33. An output from the feedback network 32 is positively fed back to the inductor 20, and the frequency counter 33 outputs a distance measurement output signal 34.