| 摘要 |
The present invention relates to a method for detecting metal objects which are made to move at a constant speed along a path subjected to an alternating electromagnetic field with a fixed period created by a first coil while measuring at the terminals of a second coil the changes induced, comprising a step of determining first electrical characteristics ZoVA of the circuit in the absence of the metal object, a step of determining second electrical characteristics of the circuit VPM 0 in the presence of a metal object and using the first characteristics for ZoVA in order to calculate the impedance Zp seen at the terminals of the secondary coil, a step of comparing the impedance determined by the calculations starting with the measurements with a reference value recorded in comparison means 6. This method is implemented by a device comprising a microprocessor 6, a sampling device constituted by a static commutator 322 and a supply circuit of the primary coil 310 and by an alternating signal with fixed frequency. One application of the device and of the method consists in detecting and sorting counterfeit coins. <IMAGE>
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