Method and apparatus for currency discrimination and counting

DETAILED DESCRIPTION It is a principal object of the present intention to provide an improved method and apparatus for identifying and counting currency bills comprising a plurality of currency denominations.
It is another object of this invention to provide an improved method and apparatus of the above kind which is capable of efficiently discriminating among and counting bills of several currency denominations at a high speed and with a high degree of accuracy.
A related object of the present invention is to provide such an improved currency discrimination and counting apparatus which is compact, economical, and has uncomplicated construction and operation.
Briefly, in accordance with the present invention, the objectives enumerated above are achieved by means of an improved optical sensing and correlation technique adopted to both counting and denomination discrimination of currency bills.
The technique is based on optical sensing of bill reflectance characteristics obtained by illuminating and scanning a bill along its narrow dimension, approximately about the central section or the bill.
Light reflected from the bill as it is optically scanned is detected and used as an analog representation of the variation in the dark and light content of the printed pattern or indicia on the bill surface.
A series of such detected reflectance signals are obtained by sampling and digitally processing, under microprocessor control, the reflected light at a plurality of predefined sample points as the bill is moved across the illuminated strip with its narrow dimension parallel to the direction of transport of the bill.
Accordingly, a fixed number of reflectance samples is obtained across the narrow dimension of the note.
The data samples obtained for a bill scan are subjected to digital processing, including a normalizing process to deaccentuate variations due to "contrast" fluctuations in the printed pattern or indicia existing on the surface of the bill being scanned.
The normalized reflectance data represent a characteristic pattern that is fairly unique for a given bill denomination and incorporates sufficient distinguishing features between characteristic patterns for different currency denominations so as to accurately differentiate therebetween