METAL BODY DETECTOR

摘要

PROBLEM TO BE SOLVED: To prevent the erroneous detection of a metal body without increasing the number of part items. SOLUTION: This metal body detector comprises an LC oscillator 3 including a detecting coil 1; an oscillation driving circuit 5 for driving the LC oscillator 3 at almost constant amplitude without being influenced by the nearness of the metal body; an impedance invariable element 4 series-connected to the detecting coil 1 and almost invariable in impedance even when the metal body is in proximity; and a signal processing circuit 8 for detecting the metal body by the amplitude Vs of a voltage dividing point between the detecting coil 1 and the impedance invariable element 4.