Sheet feeding or delivering – Feeding – By means to convey sheet
Reexamination Certificate
1999-09-07
2001-05-01
Skaggs, H. Grant (Department: 3651)
Sheet feeding or delivering
Feeding
By means to convey sheet
C271S263000, C324S229000, C324S251000
Reexamination Certificate
active
06224053
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a method for verifying the correct transport of steel material, for example banknotes, particularly in an automatic cash dispenser. Furthermore, the invention relates to a device for carrying out the method.
2. Description of the Prior Art
In the case of a known automatic cash dispenser, banknotes are dispensed individually one after the other from the banknote cartridges until the amount desired by the customer is reached. During this dispensing, it is possible for a number of banknotes to be transported lying one on top of the other, which would lead to incorrect dispensing. The automatic cash dispenser therefore contains devices which detect the multiple transport of banknotes and segregate the incorrect banknotes or the bundle of banknotes.
Patent Document No. 38 16 943 discloses a method of testing sheet material by sensing the sheet material with radiation along a predetermined sensing path. The sensing takes place under the transillumination principle. On the transmission side, light-emitting diodes are subjected to a current from a controllable current source, and on the receiver side photodiodes determine the light passing through the sheet material. If a number of sheets lie one on top of the other, the signal of the photodiode drops below a predetermined limit value, and incorrect transport fo the sheet material is signaled. The set current is made up of a basic current value and a differential current value. The differential current value is determined on the basis of sample sheets in a calibrating operation. The basic current value is set such that on the receiver side the signal level lies within a predetermined measuring range.
The principle described in German Patent Document No. 38 16 943 therefor, in which current control is used and the signal level of the detector is monitored within predetermined limits, has proven successful in practice. If, however, sheet material with greatly varying transillumination properties is used, for example American dollar bills, the reliability of the determination of multiple transport of sheet material may be restricted.
German Patent Document No. 93 10 528 therefor; discloses a paper-thickness measuring device which contains a mechanical sensor. The sensor contains a sensor coil through which current flows and the impedance of which changes when an element enters its magnetic field. The depth of entry depends on the thickness of the paper. Furthermore, German Patent Document No. 33 00 320 therefor; and German Patent Document No. 37 05 304 therefor describe the use of inductive displacement pickups for measuring the thickness of paper sheets.
European Application 0 405 466 therefor; discloses a method and a device according to the preambles of claims
1
and
8
. According to this document, a Hall generator is arranged lying opposite a fixedly arranged permanent magnet, so that an air gap is formed. A magnetically conducting end of a touching lever engages in this air gap and changes the magnetic field in a manner dependent on the deflection of the touching lever. This change in the magnetic field is determined by the Hall generator, the signal of which is evaluated for determining correct transport of sheet material.
WO-A-86/00160 discloses a thickness-measuring device for banknotes. Situated opposite a Hall generator is a permanent magnet. A that is fed into the device banknote increases the distance between the permanent magnet and the Hall generator, so that a magnetic field change is produced, whereupon the resistance of the Hall generator changes. The setting of a control current for the Hall generator dependent on the type of banknote and the interaction with the sensitivity of the arrangement of the permanent magnet and Hall generator are not described in this document.
SUMMARY OF THE INVENTION
It is the object of the invention to specify a method and a device which monitors the correct transport of sheet material with high operational dependability is of a simple construction and can be used flexibly for different types of sheet material.
This object is achieved for a method by the features of claim
1
. Advantageous developments are specified in the dependent claims.
The method according to the invention uses a mechanical sensor which determines the thickness of the transported sheet material. In the event of double transport of the sheet material, double the thickness is therefore detected and the incorrect transport of sheet material can easily be established. For the thickness measurement, a magnetic sensor is used, which establishes the change in the magnetic field at a measuring location. The operating point of such a magnetic sensor can be set by a control current, i.e. the principle disclosed and successfully proven by German Offenlegungsschrift 38 16 943 therefor; of an operating-point setting by current setting can be retained. As a difference in comparison with the subject matter according to the aforementioned document, however, in the case of the invention the control current is se ton the sensor side, wherein the electronic requirements are all on the sensor side and the associated hardware can easily be set up. This control current is set such that the sensor voltage without transport of a sheet lies within a predetermined evaluation voltage range. If the transmission properties of the sensor change, this is compensated by correcting the control current. Mechanical tolerances in production, temperature influences or mechanical wear can be compensated by correcting the control current.
According to the invention, a Hall generator in the form of a semiconductor element is used as the magnetic sensor. In the case of such a Hall generator, the sensor voltage is evaluated transversely to the current flow of the control current. By setting the control current, this sensor voltage can be influenced. The Hall generator is therefore a virtually ideal component for applying the principle realized in the case of the invention of setting the control current and evaluating the sensor voltage within a predetermined evaluation voltage range.
The invention is also characterized in that the mechanical sensor comprises at least one touching lever, which bears on a surfact of the sheet material and is swiveled about an angle corresponding to the thickness of the sheet material. The touching lever bears a permanent magnet, the magnetic field of which passes thorough the active surface of the Hall generator, the magnetic field changing in a manner dependent on the deflection of the touching lever. Such a sensing system in conjunction with a magnetic field change at the measuring location is of a simple construction and can be integrated in a simple way into the transporting path of the sheet material.
According to a further aspect of the invention, a device for verifying the correct transport of sheet material is specified. This device is particularly suitable for carrying out the method according to the invention. The advantageous effects which can be achieved with the device essentially coincide with those which have already been mentioned in the explanation of the method.
REFERENCES:
patent: 5125642 (1992-06-01), Onsinger et al.
patent: 5437445 (1995-08-01), Chang et al.
patent: 5662324 (1997-09-01), Cannaverde
patent: 33 00 320 A1 (1983-09-01), None
patent: 38 16943 (1989-11-01), None
patent: 37 05 304 C2 (1989-11-01), None
patent: 93 10 528 U (1993-11-01), None
patent: 0 405 466 (1991-01-01), None
patent: 0 596 606 A1 (1994-05-01), None
patent: WO 86/00160 (1986-01-01), None
Bischke Norbert
Nottelmann Ulrich
Schiff & Hardin & Waite
Siemens Nixdorf Informationssysteme Aktiengesellschaft
Skaggs H. Grant
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