PAPER SHEET FATIGUE DETERMINATION DEVICE, BILL PROCESSING DEVICE, AND PAPER SHEET FATIGUE DETERMINATION METHOD

摘要

PROBLEM TO BE SOLVED: To provide a paper sheet fatigue determination device accurately discriminating old banknotes from new banknotes while preventing/reducing increase in size of the device and in cost, a bill processing device, and a paper sheet fatigue determination method.

SOLUTION: A sound collection part controls a microphone to collect sound generated by banknotes passing through a predetermined position. A sampling part samples an output signal of the microphone at fixed intervals (#12). An amplitude difference calculation part calculates a difference between previous sampling data and current sampling data and a difference between the current sampling data and the following sampling data as a first amplitude difference and a second amplitude difference respectively for each of sampling data (#14). A plotting part plots a point, which uses the first and second amplitude differences as X-coordinate and Y-coordinate, for each of the sampling data in the two-dimensional coordinate system using the first and second amplitude differences as an X-axis and a Y-axis (#15). A coordinate system conversion part converts the distribution of the plotted points into the distribution expressed by the polar coordinate system (#16). A determination part determines a fatigue state of a banknote based on the distribution of the plotted point.

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