Method and apparatus for obtaining physical characteristics of coins for their identification

摘要

Method and apparatus for obtaining physical characteristics of coins for their identification, which consists in submitting the coins to two consecutive stages of electromagnetic measurement, defined by a first and a second pairs of coils, in one of said pairs the coils are connected in such a manner that their magnetic fields are added and in the other in such a way that their magnetic fields are subtracted, which stages providing signals which are processed to obtain parameters representative of the coin, characterised in that the four coils are connected to each other according to a bridge configuration and in that they are supplied simultaneously with at least two, and preferably 3, signals of different frequencies, obtaining simultaneously in each stage, on passage of the coins, two full bridge signals for each frequency and a further two half-bridge signals for the highest frequency, in each case one of the signals being representative of the variation of the resistive component.