Document alignment system

Details Document alignment system Document alignment system

1999-02-16

2001-04-03

Ellis, Christopher P. (Department: 3653)

Sheet feeding or delivering

Feeding

With means to align sheet

C271S227000, C271S253000, C271S255000

Reexamination Certificate

active

06209866

ABSTRACT:

The invention relates to a document alignment system, for example for aligning documents of value such as banknotes.
In conventional document processing systems, documents are transported along a path so that they can be inspected for authenticity, value or the like and then directed to a suitable destination. Examples of such equipment include banknote sorting equipment, letter sorting equipment and the like. One of the problems with such equipment is that the documents must be transported in accurate alignment so that information can be detected from them. In many such types of equipment, the documents are supplied only roughly organised into alignment and this reduces the efficiency of the apparatus. In this context, alignment refers to the lateral position of a document relative to the transport direction and should be contrasted with skew which represents a degree of twist imparted to the document.
U.S. Pat. No. 5,577,719 describes a document alignment system in which a document is supplied to an alignment position in which a set of transversely arranged rolls can be selectively energised to move the document while it is held in the alignment position. Thereafter, the document feed is reactivated and the aligned document fed onto the next stage in the process. The problem with this approach is that the document feed has to be stopped while alignment is carried out.
EP-A-0577928 illustrates a document transport system including an alignment roller mounted on a shaft which can be pivoted through a small angle depending upon the degree of realignment required. This system can only achieve minimal realignment.
U.S. Pat. No. 5,219,159 describes a sheet de-skew and registration device in an electrophotographic printing machine. A sheet is de-skewed by driving its leading edge into a nip between two pairs of stalled or stationary rollers and then, whilst transporting the sheet between these rollers, the roller pairs and sheet are moved laterally to a required position set by detection of the edge of the sheet. The problem with this system is the need to stop the rollers to achieve part of the realignment process which restricts the speed at which the machine can operate.
DE-A-2509276 describes an alignment mechanism for transporting overlapped sheets. The sheets are transported on a series of parallel belts which are angled to the nominal sheet feed direction in order to urge one edge of the sheets towards a transport side guide. The angle of these belts is adjusted manually prior to operation of the system. In this case, it is essential that all sheets fed to the alignment mechanism have a known orientation which means that this system is not suited to many situations in which the alignment of documents is not known.
In accordance with one aspect of the present invention, a document alignment system comprises a feed system, defining an elongate path, for feeding documents along the path, the feed system being adjustable to vary the orientation of the elongate path in a lateral plane so as to cause a document to undergo a corresponding lateral shift as it is moved along the path; a detector for detecting the lateral position of a document upstream of the elongate path; and a control system responsive to the detector to adjust the feed system so that the document undergoes a desired amount of lateral movement as it is moved along the elongate path.
In accordance with a second aspect of the present invention, a method of aligning documents comprises supplying documents to a document alignment system according to the first aspect of the invention; detecting the lateral position of each document; and adjusting the feed system to cause the document to undergo a desired amount of lateral movement as the document moves along the elongate path.
This invention overcomes a number of different problems with the prior art set out above. Firstly, rather than changing the lateral position of a feed nip, the orientation of the elongate path itself is adjusted and this allows much more accurate control of the feeding of sheets to be achieved which is particularly important in the case of old sheets such as used currency and for achieving high speed operation as found in banknote dispensing and sorting apparatus.
In addition, the system enables automatic alignment of documents to be achieved by detecting the lateral position of the document upstream of the elongate path and adjusting the feed system accordingly. Typically, that adjustment will be to centralize the document but in other cases the document could be aligned with any datum position.
A further important advantage of this invention is that it enables a document to be aligned relative to any datum i.e. a “virtual datum” system. This should be contrasted with known alignment systems in which documents are aligned against a fixed datum wall.
This alignment is achieved by the control system adjusting the feed system to the appropriate lateral position. Conveniently, this is achieved by a control system including a detector which can detect the lateral position of the feed system. The control system detector could simply detect a part of the feed system but preferably the feed system includes an indicator which moves laterally with the feed system and is detected by the detector of the control system.
The use of a special indicator enhances the accuracy of the operation of the control system and allows the indicator to have a special form for example a form which varies in the lateral direction so its direction of displacement can be uniquely determined. In the preferred example, this indicator or flag has a wedge shape.
The control system could include a moveable detector which is moved in response to the desired amount of lateral movement of the document, the control system always centering the indicator with the detector (or positioning it within a predetermined distance of the detector). More conveniently, however, the control system detector is fixed and the control system adjusts the position of the feed system until the relative locations of the indicator and control system detector are such that a document will undergo the desired amount of lateral movement.
In one implementation, the feed system can comprise a set of rollers spaced apart along the elongate path, a number, typically all, of the rollers being laterally adjustable. However, in the preferred arrangement, the feed system comprises at least one endless belt. This has the advantage over the use of rollers in that it is simpler in construction and requires less motive power to adjust the feed system.
The control system may be arranged to adjust the position of the endless belt(s) at a location adjacent a downstream end of the elongate path, a location adjacent an upstream end of the elongate path, or at both locations. In the latter event, it is then possible also to de-skew the document.
In some cases, the feed system will define just a lower surface of the elongate path but in the preferred arrangement, the feed system comprises a plurality of endless belts arranged in upper and lower laterally spaced sets relative to the elongate path, each belt of the upper set being laterally offset from adjacent belts of the lower set. This allows more complete control of the passage of documents to be achieved while laterally spacing the belts apart has been found to improve overall operation of the system.
Typically, the feed system comprises a pulley mounted on a shaft, the pulley being coupled to the control system for lateral displacement. The pulley could form part of the feed system defining the elongate path (i.e. a roller as discussed above) or an endless belt could be entrained around the pulley.
The pulley could be slidably mounted on a shaft for lateral movement but preferably is mounted for lateral movement with the shaft. This enables the lateral movement to be achieved by moving the shaft from a position remote from the pulley. Typically, the pulley will be nonrotatably mounted to the shaft so that it can be easily driven from the shaft although this is not essential

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