| 摘要 |
The present invention relates to a method of detecting metallic foreign substances by adopting a differential detection threshold for each reception coil, which is used in a metallic foreign substance detection apparatus including a plurality of transmission coils and reception coils to detect variation of induction current induced to the reception coil due to the magnetic field caused by the current flowing through the transmission coil. The variation value of the induction current is detected by adopting the differential detection threshold with respect to each reception coil according to the position of the reception coils located in a path formed at a rear side of a paper money insertion port, so that an erroneous detection, which is caused by detecting the metallic component contained in the paper money as the metallic foreign substance, can be effectively prevented even when a bundle of paper money containing metallic components is inputted, and the metallic foreign substances can be effectively detected even when the bundle of paper money contains a metallic material, such as a stapler chip causing a relatively small variation in the induction current signal. |
