Patent ID: 6325197
Filing Date: 2001-12-04
Classification: G07D

Abstract:
A method of discriminating a coin and determining authenticity thereof, comprising the steps of:(a) arranging an exciting coil in the vicinity of one side of a coin passage inclining at a predetermined angle so that magnetic poles of said exciting coil faces the coin passage;(b) arranging two receiving coils having substantially identical characteristics in the vicinity of said one side of the coin passage so that said receiving coils are electromagnetically connected with said exciting coil and electrically connected to a differential amplifier so that the differential amplifier receives the differential input from the two receiving coils;(c) exciting said exciting coil at a predetermined frequency to produce an electromagnetic field such that said two receiving coils detect an influence of a reactive magnetic field caused by eddy current induced on a surface of the coin when the coin passes the electromagnetic field, and issue of electromotive force bias representing the influences of said reactive magnetic field as the differential input to said differential amplifier; and(d) discriminating the coin based on an output of said differential amplifier when the coin passes the electromagnetic field.