Sheet-extracting device with a cassette for receiving a stack of

Details Sheet-extracting device with a cassette for receiving a stack of Sheet-extracting device with a cassette for receiving a stack of

1996-09-16

1998-12-15

Terrell, William E.

Sheet feeding or delivering

Feeding

Separators

271126, 271152, B65H 708

Patent

active

058487867

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The invention relates to a sheet-extracting device with a cassette for receiving a stack of sheets, and to a method of controlling the pressing force of the stack of sheets against the sheet-extracting device.
Cassettes of this type are used in sheet-extracting devices, in particular in automatic banknote dispensers. The pack of banknotes located in the cassette is pressed by a pressing element against an end wall of the cassette, which is designed such that the respectively forwardmost banknote is in contact with extracting elements reaching through the end wall. These extracting elements are normally extracting rollers, but may also be extracting fingers or the like.
It is already known to press the pack of banknotes by a sprung pressing plate against the extracting elements, the pressing plate triggering the control of a pressing slide by means of a displacement sensor. In this case, it is scarcely possible to ensure a constant pressing force, since the friction of the banknotes in the cassette changes with the number of banknotes in the pack and according to their condition (bends, folds and the like).
In the case of a known sheet-extracting device of the type mentioned as disclosed in DE 34 34 780 C2, the pack of banknotes is pressed against the extracting rollers by means of a pressing plate, which is displaced in the cassette by a motor. In that case, the pressing force of the extracting rollers against the forwardmost banknote is measured and used for controlling the drive motor. For that purpose, the spindle of the extracting rollers is mounted displaceably in the pressing direction on one side, it being supported directly against a force sensor. The bearing force measured by the force sensor is directly proportional to the pressing force of the stack of sheets on the extracting rollers.
However, the oblique position of the extracting shaft with respect to the stack of sheets, said position being caused by the yielding of the spindle on one side, creates the risk of extraction errors and of the banknotes skewing. This problem is heightened in that, in particular, stacks of banknotes are not of equal thickness over the entire surface of the stack. All the distortions, packing deformations, security-thread thickenings and gravure embossing on the note bundles result, in the case of large stacks, in changes in the stack thickness over the surface of the stack and thus also in unequal pressing forces on the extracting rollers. Compensation of these differences in thickness especially in the case of large filling quantities of, for example, more than one thousand banknotes in the cassette by virtue of a relatively high pressing force is not possible, or is possible only to an unsatisfactory extent. However, the extracting system as a whole only operates without disruption when the banknotes are extracted from the cassette in as straight and uniform a manner as possible.


SUMMARY OF THE INVENTION

The object of the present invention is to provide a sheet-extracting device with a cassette of the type mentioned at the beginning which ensures a uniform pressing force by simple means and in the case of which satisfactory extraction of the individual sheets from the stack is ensured even when the surface of the stack is not fully planar, and also to give a method by which the pressing force can be controlled.
This object is achieved by the present invention.
The invention is based on the finding that, in the case of a rotating extracting shaft with at least two extracting rollers, the only abutment of which is located between the extracting rollers and at the point of introduction of the torque, the entire pressing force acts on said abutment and can thus be measured there. This force is passed on to the drive shaft and can then also be measured in the bearings thereof. Since the ratio by which the pressing force is distributed to the bearings always remains the same, it is sufficient to measure the force at one end of the drive shaft. Guiding the floating shaft between legs of

REFERENCES:
patent: 3598400 (1971-08-01), Nelson
patent: 4548397 (1985-10-01), Runzi
patent: 4919412 (1990-04-01), Weigel et al.
patent: 5104109 (1992-04-01), Kubo
patent: 5207416 (1993-05-01), Soler
patent: 5295675 (1994-03-01), Hain

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