METHOD OF EXAMINING COIN WITH RESPECT TO IDENTITY THEREOF amp; APPARATUS FOR EXAMINING COIN WITH RESPECT TO IDENTITY THEREOF

摘要

An apparatus (10) for examining a coin comprises a first oscillating magnetic field of a first frequency generated by means of a first inductor (21), and a second oscillating magnetic field of a different second frequency generated by means of a second inductor (22). The coin (15, 16) is guided past the inductors (21, 22) so as to expose the coin (15, 16) to the first and the second magnetic field. A first and a second measuring value are generated representing the degrees of interaction between the coin (15, 16) and the first and the second magnetic field, respectively, and a weighted sum of the first and the second measuring value is provided by multiplying the first and the second measuring value by a first and a second, predetermined weighting factor, respectively, which weighting factors are characteristic of a specific coin type, and further by adding the first and the second measuring value multiplied by the first and the second weighting factor, respectively. In order to determine if the coin (15, 16) is of a specific valid type, it is determined if the weighted sum is within specific limits of acceptance which are characteristic of the specific type of coin in question. By this method, it is possible to distinguish between coins which in accordance with known logic AND decision technique have previously not been distinguishable in a reliable way. IMAGE