PURPOSE: To provide a detector which, even for a very short range, has an output characteristic with a certain inclination smaller than the inclination for a medium range.
CONSTITUTION: The detector, in which the impedance of a resonance circuit 16 varies depending on the range between the inductance L of the detector and a subject 14 for detection, includes an adaptive loop stage 18, which produces an amplified value corresponding to the range and supplies a loop current to the resonance circuit 16, and an evaluator 12 for detecting oscillator voltage supplied to the resonance circuit 16. The oscillator 10 produces an oscillating voltage which, even for a very small range, varies depending on the range, and, even for a very small range, has an output characteristic with an inclination smaller than an inclination for a medium range.
MIHIYAERU FURIIDORITSUHI
ERUNSUTO GASU
