Method of detecting false data recording media and a data recording medium therefor

DETAILED DESCRIPTION It is therefore an object of the present invention to provide a method of detecting false or counterfeit data recording media and a data recording media therefor which precludes the use of false or counterfeit data recording media to an extent at least sufficient to discourage the use of false data recording media.
The foregoing object is achieved in accordance with the method of the present invention wherein an automatic service machine currently presented a data recording medium performs the following steps, in addition to rendering the selected service and subtracting a corresponding amount from the current credit: Firstly reading and memorizing a serial number encoded on the current data recording medium to identify the same; Secondly reading and memorizing the number of prior uses of the current data recording medium as encoded on the data recording medium; Thirdly reading the serial number encoded on the current data recording medium of at least one other data recording medium which during prior use of the current data recording medium was encoded thereon by the automatic service machine then used; Fourthly reading the number of previous uses of the at least one other data recording medium as encoded on the current data recording medium by the automatic service machine used in such prior use of the current data recording medium and thus currently encoded on the data recording medium; Incrementing by one the number of uses encoded on the data recording medium currently presented; Firstly encoding on the current data recording medium the serial number of at least one data recording medium presented previously to the automatic service machine currently used, said serial number having been memorized in that machine; Secondly encoding on the current data recording medium the number of uses of the at least one data recording medium previously presented to the automatic service machine currently used, the number of uses having been memorized by said machine; Comparing the number of previous uses of the current data recording medium as memorized in the currently used automatic service machine with the number of its previous uses as read; and triggering a counterfeit detection signal in case the number read is lower than the number memorized