Patent GB-1531312-A (GB)
Title: Note discriminating apparatus
IPC: G07D7/00
Filed: 1976-05-06
Abstract: 1531312 Bank note discrimination GLORY KOGYO KK 6 May 1976 [13 May 1975 (2) 18 Sept 1975] 18515/76 Heading G4X A bank note discriminating apparatus has detector means for detecting characteristics of a bank note and reference level generating means for processing an output from the detector means to form a reference level signal, the output from the detector means being compared with the reference level signal from the reference level generating means to discriminate whether the bank note is a true bank note or a false bank note and to discriminate a denomination of the bank note. A note 6 inserted into a note inlet is continuously conveyed in the direction of arrow 86 along a note conveying path and is passed through a note discriminating position 87 in which position it is detected by a predetermined position confirming detector 7. First second and third detectors 85A, 85B and 85C are disposed to confront the rear end point, the central point and the front end point, respectively when the note has arrived at the note discriminating position 87. As the note passes through position 87 the detectors 85A, 85B and 85C produce detection outputs P A , P B  and P C  corresponding to the light transmission quantities of the three points of the note. A discrimination circuit 10 comprises a level detecting section 91 constituted by level detectors 90A, 90B and 90C which receive detection outputs P A , P B  and P C  through polarity conversion amplifiers 89A, 89B and 89C and also receive a reference level signal SO from a reference level signal generating section 92. The reference level signal generating section 92 as shown in Fig. 4 comprises a reference level decision circuit 93 constituted by an integration current, and a reset circuit 94 provided for the decision circuit. The reference level decision circuit 93 comprises an operational amplifier 96 receiving the detection output P A  through an input amplifier 95, a capacitor connected between the input and the output of operational amplifier 96, and an output amplifier 99 through which the integration output of the integration circuit 98 is delivered as the reference level signal SD. As indicated in D of Fig. 3 the reference level signal SD is at a 'O' level before time instant t 1  when a note reaches detector 85A and also for the period of time during which the detection output P A  is at the 'O' level. However, for a period of time after the time instant t 1  till the note has passed through the first detector 85A, the detection output P A  has an alternating current waveform at a level corresponding to light transmission quality of the note, and the variation of the reference level signal SD has a gradient corresponding to the light transmission quality of the note. Thus the levels of the outputs of the detectors 85A-C are levels corresponding to the light transmission qualities of the note and the output SD of the reference level decision circuit 93 reaches a level LJ at the time instant t 4 , which level is a value corresponding to the combination of the stain, damage and thickness of the note. The detectors are optical detectors but they may be replaced by magnetic detecting means. In another embodiment, Figs. 6-9 (not shown), the detectors are activated prior to a note reaching the discriminating position and the readings therefrom are averaged for the area scanned. A magnetic characteristic discriminator, a dimensional characteristic discriminator and a colour characteristic discriminator (not shown) produce discrimination signals JA, JB, JC respectively.