Registers – Systems controlled by data bearing records – Banking systems
Reexamination Certificate
1999-05-05
2001-05-29
Frech, Karl D. (Department: 2876)
Registers
Systems controlled by data bearing records
Banking systems
C902S008000, C902S013000
Reexamination Certificate
active
06237847
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to an apparatus for detecting the passage of multiple superposed sheets along a feed path. The invention has application, for example, to an apparatus for detecting the passage of superposed currency notes in an automated teller machine (ATM).
In a cash dispensing mechanism of an ATM, it is important to provide a simple and reliable means for detecting when a currency note has become superposed on another in a path of travel from a currency supply means to a note exit slot, since such superpositioning may produce an undesirable result such as the dispensing of an excessive amount of money. For convenience, two or more sheets or notes which have become disposed in a superposed relationship will hereinafter be referred to as a multiple sheet or a multiple note.
A known system for detecting multiple sheets includes a sensing station in a feed path for the sheets. The sensing station includes a light emitter and an optical sensor arranged to sense light from the emitter transmitted through an item comprising a single or multiple sheet present at the sensing station. The optical sensor provides an output voltage whose magnitude is dependent on the intensity of the transmitted light received by the optical sensor. The output voltage of the optical sensors is applied to a processing circuit, and on the basis of this voltage the processing circuit provides an output indicative of whether a single sheet or a multiple sheet is present at the sensing station.
With this known system problems have been experienced in reliably distinguishing between a single bank note and a double bank note, and between a single clean bank note and a single soiled bank note. The reason for this is that the voltage output of the optical sensor when the light incident on it has passed through one note is typically 20% of the output of the optical sensor when light from the emitter has reached the sensor directly (i.e. with no note present at the sensing station), and that the voltage output of the optical sensor when the incident light has passed through two notes is typically only 20% of the output of the sensor when the incident light has passed through one note. For example, if the output of the sensor when no note is present at the sensing station is 5 volts, the output of the sensor with one note present would typically be 1 volt and the output with 2 notes present would typically be 0.2 volt. It is seen that there is a relatively large difference between the sensor outputs for no and one note present, but a relatively small difference between the sensor outputs for 1 and 2 notes present. Thus, there is not a very clearly defined difference as regards the sensor output for single and multiple notes, and the very low sensor output for a multiple note may approach the noise level of an analog to digital (A/D) converter included in the circuit used to process the output of the sensor.
Another known system for detecting multiple sheets is disclosed, for example, in EP-B-0344938. This system includes first and second co-operating rollers between which sheets pass as they are fed along a feed path, the first roller having a fixed axis of rotation, and the second roller being resiliently urged towards the first roller so as to enable it to be moved away from the first roller as a single or multiple sheet passes between the rollers. A voltage generating means associated with the second roller produces an output voltage which varies linearly with movement of the second roller towards or away from the first roller, and this output voltage is applied to a processing circuit which determines whether a single or multiple sheet has passed between the rollers. This known system has the disadvantage that it is relatively complicated compared with the known multiple sheet detector system using an optical sensor.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a system for detecting multiple sheets which is of simple construction and in which the above-mentioned problems of the known system employing an optical sensor are alleviated.
According to the invention there is provided a system for detecting the passage of multiple superposed sheets along a feed path, said system including a sensing station through which said feed path passes and which has a light emitter and an optical sensor arranged to sense light from said light emitter transmitted through an item comprising a single or multiple sheet present at said sensing station, said optical sensor providing a voltage output whose magnitude is dependent on the intensity of the transmitted light received by said optical sensor, characterized by a log ratio amplifier having first and second inputs and an output, the output of said optical sensor being applied to said first input, and a voltage representative of the output of said optical sensor when no item is present at said sensing station being applied to said second input; and data processing means to which the output of said amplifier is applied, said data processing means being arranged to make a determination as to whether a single or multiple item is present at said sensing station on the basis of the output of said amplifier.
It should be understood that by a log ratio amplifier is meant an operational amplifier circuit having two inputs and an output, and the output voltage of which is proportional to the log of the ratio of input voltages respectively applied to the two inputs.
Preferably, in a system in accordance with the invention, the output of the log ratio amplifier varies linearly in dependence on whether no, one or two sheets are present at the sensing station.
Also, preferably in a system in accordance with the invention, in the event of a multiple sheet being present at the sensing station the processing means makes a determination as to whether the multiple sheet comprises 2 sheets or 3 sheets.
It should be understood that the ability of such system to determine the number of sheets making up a detected multiple sheet is of importance, since when it is used in a cash dispensing mechanism, for example, it enables a record to be kept of the number of notes making up a multiple note which will normally be diverted to a reject bin. Such record will assist in reconciliation procedures when the bin is emptied. In operation of a cash dispensing mechanism, it is very unlikely that a multiple note would comprise more than 3 notes.
REFERENCES:
patent: 4154437 (1979-05-01), Butcheck et al.
patent: 4352559 (1982-10-01), Gorgone et al.
patent: 4501416 (1985-02-01), Hain
patent: 4513439 (1985-04-01), Gorgone et al.
patent: 4577763 (1986-03-01), Placke et al.
patent: 4815015 (1989-03-01), Milne
patent: 0335561 (1989-10-01), None
patent: 0344938 (1989-12-01), None
Frech Karl D.
NCR Corporation
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