Document handling apparatus is used= for handling a variety of documents such as documents of value, for example banknotes. In these applications, it is very important to ensure that the documents are correctly counted i. e. identified as single documents. Typically, documents to be counted are loaded into an input hopper and then extracted one by one so as to be fed past various sensors and detectors to one or more output pockets.

Examples include banknote counters, sorters, recirculators and the like. To ensure that the banknotes are fed singly, a separation system is utilized to deal with double fed notes and the like. However, occasionally notes will still be fed in the form of doubles and thus it is essential to include a doubles detector downstream of the separator.

Conventional double detectors comprise opacity detectors for detecting the opacity of the"note"being fed by a transport usually utilizing a radiation beam transmitted through the note or a mechanical device which is deflected in accordance with the thickness of the note or notes being transported.

In addition, various authenticity tests are carried out so as to avoid counting counterfeit or wrong denomination notes. This is typically handled using pattern recognition devices and an example is the De La Rue 2800 machine.

One of the problems associated with the doubles detect devices that use an implied rather than an explicit thickness is that they can lose accuracy or suffer performance degradation as a result of variations within the notes. For. instance an opacity system can be affected by variations within notes from features such as watermarks and by design changes introduced when notes are re-issued.

An example of this can be seen by reference to the Chinese

Yuan note where the new issue 100 has an opacity that is substantially lower than the previous issue note.

In a traditional note counter or other handling devices that can only count one denomination or note type at a time the effects of note variations have not been significant. However, in a value balancing product, where all note types can be mixed together this can cause difficulties. The traditional and obvious technique when such variations occur on different denominations is to tie the doubles detect threshold to the denomination or type of the note. This technique however does not work when notes of the same denomination and of identical design (i. e. same issue) suffer such variations. Such variations arising perhaps from different print runs (i. e. time and place of manufacture) material variations within the note production (e. g. different paper suppliers) or a combination of both effects.

In this context"count"means simply the correct handling of a single document. It may also be accompanied by the increment of a count value.

In accordance with one aspect of the present invention, document handling apparatus comprises a transport system; and a pattern recognition system past which documents are transported by the transport system, the pattern recognition system being adapted to obtain an image of each document, to compare the image with one or more reference images, and to recognise the document only when the comparison satisfies predetermined conditions, wherein the predetermined conditions are defined so as at least to distinguish between single spaced documents on the one hand and overlapped or stream fed documents on the other hand, and wherein the document is recognised solely on the basis of the outcome of the comparison.

In accordance with a second aspect of the present invention, a method of handling documents transported past a pattern recognition system comprises obtaining an image of each document, comparing the image with one or more

reference images, and recognising the document only when the comparison satisfies predetermined conditions, wherein the predetermined conditions are defined so as at least to distinguish between single spaced documents on the one hand and overlapped or stream fed documents on the other hand, and wherein the document is recognised solely on the basis of the outcome of the comparison.

We have realised that it is possible to utilize a pattern recognition system not just for determining the image on a document from which, for example, its denomination can be determined and possibly also its authenticity, but also whether or not a single document is being fed. In this way, a separate doubles detector can be omitted all together and all processing can rely on the single pattern recognition system. This design simplification reduces the product component count and thereby reduces its cost.

The invention is also applicable to security document accepting machines, for example machines for vending goods and/or services requiring more than one document being offered for the vend, or in equipment for automatically debiting an account with the value of more than one document inputted. These equipments are in the main concerned with the"value"and/or"total value"figures and validity of the documents submitted for each transaction.

Furthermore, the"action"which might arise from the documents being inputted could, as well as"flagging"the fact that the inputted value is accepted (counted) or not (not counted) to determine how the primary process, e. g. vend, is to continue, could also"flag"some further action, for example, diverting, signal indicating or visual screen change.

Pattern recognition systems that determine the denomination of a banknote by processing its image can be created in two fundamental forms, transmissive or reflective. The reflective devices obtain an image from just the face of the note facing the imaging device and

transmissive devices produce an image containing information from both faces of the note simultaneously.

The latter achieves this imaging by having the illumination source and image receptors arranged such that the note passes through a gap between the two portions thereby causing light to pass through the note before it reaches the image receptors.

The invention that will be disclosed is primarily intended for application to the transmissive devices and the preferred embodiments described below will be provided on this basis. It is however possible to achieve a similar version of the functionality using a reflective device.

When documents are being fed one at a time the pattern recognition system will be able, by using the acquired image, to determine the denomination, face, orientation, issue, size etc of the document. If however the documents should mis-feed for some reason such that they become overlapped to any extent or form a continuous or quasi- continuous stream than this will be detected. This detection will be achieved from one or more of the factors listed below: Corruption of the image Changes in the size of the note Changes in the interval between the notes The above list is of course not exhaustive but does illustrate some of the main distinguishing factors.

Any failure to identify the document as a valid single document is of course equivalent to identifying the document as being a double or stream feed. Valid identifiable documents may therefore be counted as single and all other cases can be considered reject for handling by whatever means may be available within the machine (divert, machine stop, etc).

The benefits of this approach are many fold: The machine can achieve the counting operation without the need for a separate-doubles detect

device. This of course both simplifies and cost reduces the resulting product.

The machine can accurately count documents of mixed types without recourse to complex multiple threshold systems.

The approach overcomes the problem disclosed earlier of notionally identical documents having varying properties arising from multiple manufacturing sources or print runs. A problem . not soluable with multiple thresholds.

The pattern recognition system may obtain an image of the whole document but in some cases, in order to simplify processing, an image of only a part of the document may be needed.

Typically, the radiation source will generate radiation in the visible wavelength range although infrared and ultraviolet radiation may also be used depending upon the nature of the documents being counted.

The apparatus and method can be applied to a wide variety of apparatus including those which have more than one output location for sorting purposes and those which have a single output location, the machine stopping or otherwise flagging documents which should not be counted.

Some examples of banknote counters according to the present invention will now be described with reference to the accompanying drawings, in which:- Figure 1 is a schematic diagram showing the primary transport components of a first example; and, Figure 2 is a view similar to Figure 1 but of a second example.

Figure 1 illustrates a banknote counter 100 having an input hopper 2 mounted beneath an inlet opening 3 in an enclosure 1 which comprises upper and lower parts la, lb normally screwed together. Contained within the enclosure 1 is an internal chassis assembly (not shown for clarity) which itself has side members between which the sheet

feeding and transport components to be described herein, are mounted. Two conventional feed wheels 5 are non-rotatably mounted on a shaft 7, which is rotatably mounted to the chassis assembly, and have radially outwardly projecting bosses 6 which, as the feed wheels rotate, periodically protrude through slots in the base of the hopper 2.

A pair of stripper wheels 15 are non-rotatably mounted on a drive shaft 16 which is rotatably mounted in the chassis assembly. Each stripper wheel 15 has an insert 17 of rubber in its peripheral surface. Shaft 16 is driven clockwise by a motor (not shown) to feed notes individually from the bottom of a stack of notes placed in the hopper 2.

Transversely in alignment with, and driven from the circumferential peripheral surface of the stripper wheels 15, are pressure rollers 30 which are rotatably mounted on shafts 31 spring based towards the stripper wheels 15.

Downstream of the wheels 15 is a pair of transport rollers 19 non-rotatably mounted on a shaft 20 rotatably mounted in the chassis assembly. Shaft 20 is driven clockwise from a second motor (not shown) to transport the note in the transport arrangement, in conjunction with pairs of pinch rollers 21,23 into stacking wheels 27 and hence output hopper 105. Pinch rollers 21, rotatably mounted on shafts 22 spring based towards the transport rollers 19, transversely align with rollers 19 and are driven by the peripheral surface of the rollers 19. The rollers 23, rotatably mounted on shafts 24 are in alignment with the transport rollers 19, and are essentially caused to rotate by the note passing between the adjacent peripheral surfaces of the rollers 19 and 23.

Situated between the pressure rollers 30 and pinch rollers 21 are separator roller pair 25, non-rotatably mounted on shaft 26 adjustably fixed to a top moulding assembly 32, having a circumferential peripheral surface which is nominally in alignment with the peripheral

circumferential surface of, but transversely separated from, the stripper wheels 15.

Also forming part of the top moulding assembly 32, is a curved guide surface 8 extending partly around the circumference of the rollers 15,19 which, when the top moulding is lifted allows the operator access to the note feed and transport path so that a note jam can be cleared.

A surface 37 provides note guiding from the end of the curved guide surface 8 to the conventional stacking wheels 27.

The drive shaft 16 is continuously driven, and this, via a belt and pulley arrangement from shaft 16, causes the auxiliary drive shaft 7 rotating the feed wheel 5 also to be driven. Drive shaft 20, rotating the transport rollers 19, is driven by the other drive motor. A further pulley and belt arrangement (not shown) between shaft 20 and shaft 28, on which the stacking wheels 27 are non-rotatably mounted, provides the drive to the stacking wheels 27.

A guide plate 9 extends as a continuation of the base of the hopper 2 towards the nips formed between the transport rollers 19 and the rollers 23.

A pattern recognition system 50 including a linear photodiode array is mounted adjacent to the transport path.

The array extends across the full length of the banknotes (transverse to the feed direction), so as to detect light originating with a light source 50A transmitted through the banknotes as they pass beneath the detector. (Other known detectors could be used which, for example, only scan a portion or portions of the banknotes.) The system 50 includes an on-board processor which samples the photodiode outputs regularly.

Sampled photodiode output signals are digitized and stored and then compared with a set of prestored images.

Where the counter 100 is to count a single denomination then the prestored images will correspond to the appearance of that denomination in all possible orientations. If the counter 100 is to form a"value balancing"count of mixed

currency then the prestored images will define the appearance of each currency in all its orientations. This is a particularly important application of the present invention since notes of different thickness would typically be mixed together within the same batch. The microprocessor within the pattern recognition system 50 is adapted to apply sufficiently stringent criteria to each comparison so as to be able to distinguish between single fed notes with a certain minimum distance between them on the one hand and overlapped notes (which yield a blurred image which cannot be accurately identified with any of the prestored images and/or exhibit a size which falls outside an expected size) and stream fed notes (where the distance between the notes is less than the predetermined minimum) on the other hand.

In addition, the pattern recognition system will also determine whether or not the note is of the expected denomination (in the case of single denomination counting) or one of the expected denominations (in the case of mixed denomination counting) and will increment a count accordingly. The count will typically be a count of the people value of the notes being counted although in some cases it could simply represent the number of notes.

If the microprocessor in the pattern recognition system 50 determines an unacceptable condition such as a corrupted image, an indefinable image or the like then it will cause one or both of the drive motors to stop so that the unacceptable note or notes will be stacked at or near the top of the stack formed in the output hopper 105. The entire stack can then be refed or the operator, in some cases, can adjust the count either to decrement it if the notes are to be removed or to increment it as necessary if the notes are, in fact, acceptable.

The counter 100 shown in Figure 1 has a single output hopper 105. The invention is also applicable, however, to counters/sorters having multiple output hoppers and Figure 2 illustrates such an example with two output hoppers. The

Figure 2 counter 300 has an input hopper 401 having a base 402 with an aperture 403, through which a high friction portion 404 of a nudger wheel 405 can project. The base 402 optionally has a second aperture 406 in alignment with a barcode reader 407 for reading data on note separators.

Bank notes are supported in a stack on the base 402 against a front wall 426, and are fed intermittently by rotation of the nudger roller 405 into a nip 408, between a high friction feed roller 409 and a separator, counter rotating roller 410. The nudger 405 and roller 409 are driven by a motor 200 (not shown). The documents pass through pinch rollers 411,412 into a pattern detection region 413 in which a sensor of a transmission pattern recognition system 414A, 414B (414B indicating a radiation source) scans the bank note as it is fed and passes information back to a microprocessor of the system 414A (not shown). Each bank note is then fed through pinch rollers 416,417 onto a drive belt 418 which conveys the bank note around various rollers 419 to a diverter 420. At least one of the rollers is driven by a motor 210 (not shown). The position of the diverter 420 is controlled by the microprocessor of the system 414A, so that bank notes are guided either towards an output pocket 421, where they are stacked using a rotating stacking wheel 422 in a conventional manner, or to a reject bin 423.

As can be seen, the bank notes are stacked on the base 402 and are urged forward against the front wall 426. A small gap 427 is provided at the base of the front wall, through which individual bank notes and separators can be nudged.

The pattern recognition system 414A, 414B operates on the detected image data in an exactly similar way to the pattern recognition system 50 of the previous example. In this case, however, instead of stopping the transport when an unsatisfactory condition is determined such as a double note feed or the like, the diverter 420 is operated so that the unacceptable notes are fed to the reject bin 43.