Paper-like piece identifying method and device

Abstract

Detected data for a plurality of predetermined positions on a particular bill to be identified are each converted into relative-value data to a minimum value of the detected data for the individual positions, to extract a characteristic pattern of designs printed on the bill. The relative-value data are normalized by use of a relative value standard average to provide adjusted sample data. Then, for each of the positions, a distance value indicating how many times a difference of the adjusted sample data from the standard average is greater than a standard deviation (namely, standardization variable) is evaluated, to effect further normalization. The bill is then identified by judging whether or not the thus-normalized adjusted sample data, i.e., distance value for each of the positions, falls within a predetermined determination-standard-value range. Further, the distance values for the individual positions may be summed up to provide a totalized distance value, and the totalized distance value may be compared to a predetermined determination standard value to identify the bill. Provision of an approximate denomination table achieves increased identification accuracy in relation to two or more denominations that are approximate to each other. By previously setting determination standard data in relation to a particular denomination for which false bills may be frequently encountered, such false bills can be eliminated reliably with increased efficiency.