| 摘要 |
PROBLEM TO BE SOLVED: To simplify loop-coil installation work by setting a circuit capable of detecting a feeble inductance variation of a one-turn loop coil and adopting a one-turn loop coil. SOLUTION: A loop-coil type metal object detector includes: a loop coil 1 consisting of one coil of electric wire; a resonant circuit provided, connected to the loop coil 1, for detecting a signal variation based on loop coil inductance; an oscillation circuit configured in combination with the resonant circuit; a determination circuit 10 for determining whether a frequency or peak value of an output of the oscillation circuit is within a predetermined range; and a refresh circuit for discharging an electric charge accumulated in a capacitor of the resonant circuit through short circuiting at a predetermined interval. COPYRIGHT: (C)2011,JPO&INPIT |
