Sheet feeding or delivering – Feeding – With means to interrupt feeding
Patent
1990-01-17
1991-04-30
Bollinger, David H.
Sheet feeding or delivering
Feeding
With means to interrupt feeding
271263, 271265, 271272, B65H 712
Patent
active
050111272
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to an apparatus for detecting documents moving along a track. It particularly relates to an apparatus operative to detect the movement of two or more documents together down the track.
Document tracks are used in document encoding and cheque sorting machines. Tracks are also used for moving letters and mail, bank notes and indeed, any thin planar items. Should more than one document move down a track at the same time, multiple documents are presented to work stations along the track and erroneous operation occurs. It is therefore important to detect when more than one document moves along a track.
It is known to provide pneumatic suction along both sides of a track. A single document is attracted to a suction nozzle on only one side of the track, whereas a multiple document provides attraction to suction nozzles on both sides of each track. By sensing the increase in pressure on each side of the track, a multiple document is detected. This is an expensive solution in that a pneumatic vacuum source is required together with pneumatic sensors.
It is also known to shine light across the path of an advancing document. If a fall in light level is detected, a document is signalled as being present. If, whilst a document is present, a further sharp fall in light level is detected, it is signalled that multiple documents are present.
Should multiple documents be detected, the document processing machine or other apparatus is stopped for the multiple document to be removed. Alternatively, automatic diverting means can be brought into play to divert the multiple documents from the track or to separate the documents. Such further means do not form part of the present invention.
In the photo-optic approach it is very difficult indeed to detect multiple documents when two documents are presented, moving along the track, with their leading edges aligned, since no further sharp fall in light transmission will be perceived, the sharp fall having all occurred along the leading edge of the two documents.
The present invention seeks to provide detection of multiple documents moving along a track where the documents can be aligned at their leading edges but avoiding the complication of the pneumatic method.
In the preferred embodiment of the present invention, since it is known and usual to urge the document along the track by a pair of opposed wheels, one of which is driven, it is provided that the combination of the driven wheel and the idler wheel serves the secondary and dual purpose of driving the document along the track. A synergistic combination is thereby obtained, a dual function being served by one set of items.
While the invention allows for the idler wheel to be maintained in its preferred position by means of springs and other elastic members, it is preferred that the idler wheel is maintained at the distal end of a castor arm fixed in association with the track. In the preferred embodiment the idler wheel remains in the preferred position when a single document is in the nip by virtue of a castoring action against the moving document. Likewise, when no document is in the nip, the idler wheel is maintained in the preferred position by a castoring action against the drive wheel.
In the preferred embodiment the displacement means for the idler wheel comprises an electromagnet operative to attract a magnetic core provided in association with the bearing whereon the idler wheel rotates.
In the preferred embodiment of the present invention, operation of the document detector is not continuous, but is dependent upon a document presence sensor detecting when a document enters the nip. The displacement means (i.e., the electromagnet) is operated only when the document presence sensor indicates that a document is in the nip. In this manner the idler wheel is always in its preferred position prior to entry of a document into the nip.
The preferred embodiment also provides that the idler wheel, in being urged away from its preferred position, transversely to the direction of movement of a docu
REFERENCES:
patent: 3176981 (1965-04-01), Vandeman
patent: 4550252 (1985-10-01), Tee
patent: 4664369 (1987-05-01), Graef et al.
Hamilton Thomas A.
Kerrigan Michael M.
Wilson John A.
Bollinger David H.
Scott Thomas J.
Starr Mark T.
Unisys Corporation
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