The Discrimination of Metallic Coins Using a Scan Type Magnetic Camera

Abstract

Coins from different countries having similar sizes and weights could be used in a crime because they may have a large difference in economic value. An algorithm, which can be used to discriminate these coins, employs a scanning magnetic camera, which uses a linearly integrated 64 InSb Hall sensor array (LIHaS) on a NiZn ferrite wafer and a complex induced current-magnetic flux leakage method (CIC-MFL). The coins consist of paramagnetic metals or magnetically combined metals. The distribution of the magnetic field around each coin was measured at a lift-off of 1mm, and processed by using the V RMS / x term. It is possible to apply the peak-distances and the integrated absolute minimum values of V RMS / x in order to discriminate the coins. 170 cases that used 85 coins of 43 different denominations from 10 countries were examined to verify the proposed algorithm. The discrimination probability was 90.7 %.