Bill identification apparatus

A bill identification apparatus comprising:

• transportation means for transporting bills along a transportation path;
• detecting means in the transportation path for sampling the bills in synchronism with the bill transportation speed, detecting the physical properties of the bills in each of detection positions i, and outputting detected data pi for the detected properties;
• memory means for storing standard pattern values pci, indicative of average values for the individual detection positions i computed in accordance with the detected data pi obtained by sampling a number of authentic bills by said detecting means, and standard deviation values psi indicative of the degrees of scattering of data in the detection positions i;
• correction value computing means for obtaining a correction value pm for making an average value of the detected data pi for a detection section, detected by sampling the bills to be identified by said detecting means, equal to an average value of the standard pattern value pci for the detection section;
• heterogeneity computing means for obtaining a heterogeneity pr by correcting the detected data pi, detected by sampling the bills to be identified by said detecting means, using the correction value pm, then subtracting the corresponding standard pattern value pci from thus corrected detected data value pi, and integrating the square of the resulting remainder divided by the corresponding deviation value psi, for a detection frequency corresponding to the detection section;
• and
• discriminating means for concluding that a bill is authentic only when the correction value and the heterogeneity are within respective predetermined tolerances thereof.