| 摘要 |
PROBLEM TO BE SOLVED: To provide a metal detector capable of increasing a detection sensitivity for a minute metal, despite of a low power consumption.SOLUTION: A metal detector 10 includes: a magnetic field generation part 1 for applying a magnetic field to a test object 3; and a magnetic field detection part 2 for detecting a change of a magnetic field generated by a metal containing the test object 3. The magnetic field generation part 1 has a signal generation source 11; an electric power amplification part 12; and an exciting circuit comprising an exciting coil 13 and a first capacitor 14. The magnetic field detection part 2 has a detection circuit comprising the detection coil 21 and a second capacitor 22 and a signal processing circuit 23 for processing the detected detection signal. The exciting circuit and the detection circuit constitute a resonance system. The frequency of the signal generation source 11 is either a resonance frequency of the resonance system or the frequency within ±10% of the resonance frequency.SELECTED DRAWING: Figure 1 |
