WO2008119920A1

WO2008119920A1 - Sheet sensing apparatus and method

Info

Publication number: WO2008119920A1
Application number: PCT/GB2007/001199
Authority: WO
Inventors: Simon Calverley
Original assignee: Talaris Holdings Limited
Priority date: 2007-03-30
Filing date: 2007-03-30
Publication date: 2008-10-09
Also published as: AP2009004961A0; AR067288A1

Abstract

A sheet sensing apparatus for detecting the passage of sheets therethrough is disclosed. The sheet sensing apparatus comprises a shaf t (1), at least one roller assembly mounted on the shaft, a guide surface (20), the at least one roller assembly (6) cooperating with the guide surface to define a nip therebetween, sensing means (10) for sensing deflection of the at least one roller assembly relative to the guide surface in response to the passage of one or more sheets through the nip, monitoring means connected to the sensing means for monitoring the sensed deflections of the at least one roller assembly and at least one cleaning assembly (30) arranged to cooperate with the at least one roller assembly. The at least one cleaning assembly comprises a first cleaning member(31) and a second cleaning member(32). The cleaning assembly is movable between a first position in which the first cleaning member contacts the roller assembly whilst the second cleaning member is spaced from the roller assembly, and a second position in which the second cleaning member contacts the roller assembly.

Description

SHEET SENSING APPARATUS AND METHOD

This invention relates to apparatus and methods for detecting the passage of sheets through a sheet transport mechanism. In particular, the invention is concerned with preventing the build up of dirt on such apparatus which could otherwise impair the ability of the apparatus to accurately detect sheets. The apparatus and method are particularly well adapted for use in handling documents of value, such as banknotes, certificates, cheques etc., but could also be advantageously employed in other applications. The following disclosure will focus in the main on the handling of banknotes, but it will be appreciated that the invention is more widely applicable.

In many document handling apparatus, such as banknote counters or sorters, it is necessary to count sheets passing through the apparatus and to detect the simultaneous passage of two or more sheets or sheets of an incorrect size. This is achieved using an sheet sending apparatus, usually referred to as a Doubles Detector.

Various techniques for sensing sheets are known, including optical methods relying on the opacity of the sheet material and mechanical techniques involving measuring changes in capacitance or fluid pressure. One technique which has been found to work particularly well is disclosed in EP-A-0130824. The apparatus comprises at least one roller assembly mounted on a shaft opposing a guide surface. The roller assembly is mounted on the shaft via a resilient portion and means are provided within the shaft for sensing deflection of the resilient portion relative to the shaft in response to the passage of one or more sheets through the nip defined between the roller assembly and the guide surface.

However, in this type of sensing apparatus as well as others, the accuracy of the device can be compromised if dirt or dust is present on any of the sensing components. In particular, using a device such as that disclosed in EP-A- 0130824, it has been found that dirt and dust can build up on the surface of the roller assembly to the extent that the deposit contacts the opposing guide surface, causing a deflection of the resilient portion even when no sheet is passing. This is a particular problem in regions having dusty atmospheres such as Africa and South America, where banknotes in circulation often become dirty. Similar problems are experienced in all such sensing devices which effectively depend on detecting changes in the spacing between two opposing sides of a nip.

The present invention provides a sheet sensing apparatus comprising a shaft, at least one roller assembly mounted on the shaft, a guide surface, the at least one roller assembly cooperating with the guide surface to define a nip therebetween, sensing means for sensing deflection of the at least one roller assembly relative to the guide surface in response to the passage of one or more sheets through the nip, monitoring means connected to the sensing means for monitoring the sensed deflections of the at least one roller assembly, and at least one cleaning assembly arranged to cooperate with the at least one roller assembly, the at least one cleaning assembly comprising a first cleaning member and a second cleaning member, wherein the cleaning assembly is movable between a first position in which the first cleaning member contacts the roller assembly whilst the second cleaning member is spaced from the roller assembly, and a second position in which the second cleaning member contacts the roller assembly.

By providing a cleaning assembly in this way, it is possible to clean the surface of the roller assembly straightforwardly, without having to disassemble the machine. The first cleaning member can be used to provide continuous cleaning, by constantly contacting the roller assembly as it rotates in use. This clears dust which might otherwise be building up before it can become compacted onto the roller surface. The second cleaning member is maintained out of contact for this period to avoid undue wear. However, should stubborn deposits of dirt form on the roller assembly despite the action of the first cleaning member, the cleaning assembly can be moved into its second position in which the second cleaning member contacts the roller surface to clear any dirt buildups. This enables the user to clean the assembly easily, without the intervention of a service technician and hence allows longer time intervals between service calls. Preferably, in the second position, the first cleaning member is spaced from the roller assembly. However, in other examples, it could remain in contact with the roller assembly so as to assist in cleaning.

Advantageously, the cleaning assembly comprises a support member on which the first and second cleaning members are mounted, the support member being movable relative to the at least one roller assembly. This provides a convenient "one-piece" construction which can be manufactured separately and easily retrofitted to existing machines. Preferably, the support member is pivotable relative to the roller assembly, but could alternatively be deformable, slidable or otherwise mounted so as to allow movement relative to the roller assembly.

Preferably, at least one of the first and second cleaning members is an integral part of the support member to further simplify construction by reducing the number of parts and provide a robust component.

Advantageously, the support member is of a resilient material. This can permit relative movement of the two cleaning members, in addition to the available movement relative to the roller assembly. Where one of the cleaning members is integral with the resilient support member, it too will be resilient, enabling it to apply increased pressure on the roller assembly.

Preferably, the first cleaning member comprises a brush. This has been found to clear dirt and dust effectively from the assembly during use without undue wear. A good alternative would be to use a flexible wiper blade. Advantageously, the second cleaning member comprises a scraper. Compacted dirt build-ups have been found to be most effectively removed using a scraper.

Typically, machines employing such sheet sensing apparatus will comprise a transport mechanism including a motor which can be used to rotate the roller assembly in use. However, it is preferable that the sheet sensing apparatus comprises means for rotating the at least one roller assembly about the axis of the shaft. This makes it possible to (additionally) rotate the roller assembly independently of the operation of the machine so that, for example, the assembly can be cleaned when the transport mechanism is not operational, without the user having to touch the components. Alternatively, the operator could simply turn the rollers directly.

Advantageously, the means for rotating the at least one roller assembly are manual, and preferably comprise a handwheel for operation by a user. This allows the user complete control over the cleaning operation and avoids any safety hazards which might otherwise be encountered if the transport mechanism were used to rotate the roller assembly (typically at high speed).

In other examples, the means for rotating the at least one roller assembly are driven, and preferably comprise a motor. By providing the sensing apparatus with its own drive means, cleaning can be automated yet still carried at optimal speed (which may be slower than the usual transport speed of the machine). The apparatus could be provided with a dedicated motor, or it could utilise the transport motor via control means such as gears. A controller may also advantageously be provided for rotating the at least one roller assembly in accordance with a predetermined program.

The guide surface preferably comprises at least one guide roller opposing the at least one roller assembly, to improve transport through the system. However, a static component such as guide fingers or plates could be used instead.

The means for rotating could act directly on the roller assembly via the shaft. However, it has been found preferable that the means for rotating (including manual means) the at least one roller assembly comprises the at least one guide roller. In other words, the guide roller is driven and acts on the roller assembly to transfer rotation.

The sheet sensing device could perform sheet detection using any of the known techniques. However, it is preferable that the at least one roller assembly is mounted on the shaft by means including a resilient portion, such that deflection of the at least one roller assembly relative to the guide surface cause deflection of the resilient portion relative to the shaft, and the sensing means sense deflection of the resilient portion to determine deflection of the at least one roller assembly. This technique has been found to be particularly effective and has the added advantage that the sensing means can preferably be disposed within the shaft, making them less prone to contamination by dirt or dust.

Preferably, the at least one roller assembly includes a rigid member protruding into the shaft, the rigid member being radially movable relative to the shaft in response to deflections of the resilient portion and cooperating with the sensing means. Alternatively, the sensing need have no direct connection with the roller assembly if, for example, the resilient portion carries a magnetic element and the sensing means can sense variation sin magnetic field within the shaft (e.g. a Hall effect sensor).

In the preferred example, the sensing means includes means for generating and receiving electromagnetic radiation, the material of the rigid member being such that on deflection of the resilient portion, the proportion of electromagnetic radiation received by the receiving means varies due to movement of the rigid member. Advantageously, the generating means comprises one or more light emitting diodes, and the receiving means comprises a phototransistor.

Advantageously, the monitoring means includes detection means for detecting whether deflection of the resilient portion is caused by the passage of one or of more than one sheet through the nip. The monitoring means may also or alternatively be adapted to detect sheet size and compare it with predetermined values to identify sheets of incorrect size.

Preferably, the at least one roller assembly comprises inner and outer races surrounding bearing means, the inner race being coaxial with the shaft and being supported on the shaft by the resilient portion. Conveniently, the rigid member comprises a pin abutting an inner surface of the inner race and protruding through an aperture in the shaft.

Advantageously, the sensing means is mounted in a housing which is slidable into and out of the shaft. Preferably, the sheet sensing apparatus comprises two roller assemblies mounted on the shaft and spaced from each other. However, any number of roller assemblies (and opposing guide rollers if used) can be employed.

Where more than one roller assembly is employed, it is preferable that a cleaning assembly is provided for each respective one of the roller assemblies. For example, where two roller assemblies are provided, the sheet sensing apparatus preferably comprises two cleaning assemblies, each cooperating with a respective one of the roller assemblies. Advantageously, the two cleaning assemblies are fixed relative to one another such that they move simultaneously between the first and second positions. In some embodiments, the two cleaning assemblies may be formed as a single unit, integrated by means of at least one common component, e.g. the first or second cleaning member and/or the support member.

The sheet sensing apparatus can be used in any document handling machine, however it is particularly well suited for use in processing banknotes. Hence the invention further provides a banknote handling apparatus comprising the sheet sensing apparatus described above.

Preferably, the banknote handling apparatus comprises a base structure, to which the shaft is fixed, and a cover structure movable relative to the base structure, to which the at least one cleaning assembly is fixed. Conveniently, the cover structure is pivotably mounted to the base structure at a pivot point such that the cover structure is movable between a closed position in which the cover structure abuts the base structure, and an open position in which the cover structure is spaced from the base structure away from the pivot point. This construction can conveniently be utilised to actuate the cleaning assembly: preferably, wherein the at least one cleaning assembly is in its first position when the cover structure is in its closed position, and the cleaning assembly is in its second position when the cover structure is in its open position. Typically, the cover structure supports one or more detectors for detecting characteristics of banknotes passing through the banknote handling apparatus. The invention further provides a method of cleaning a sheet sensing apparatus comprising a shaft and at least one roller assembly mounted on the shaft, the method comprising: positioning a cleaning assembly having a first cleaning member and a second cleaning member in a first position such that the first cleaning member contacts the roller assembly whilst the second cleaning member is spaced from the roller assembly; rotating the at least one roller assembly about the shaft axis such that the first cleaning member acts against the moving surface of the roller assembly; moving the cleaning assembly into a second position in which the second cleaning member contacts the roller assembly; and rotating the at least one roller assembly about the shaft axis such that the second cleaning member acts against the moving surface of the roller assembly.

To remove stubborn dirt deposits, the method may further comprise the step of applying pressure to the second cleaning member when the cleaning assembly is in the second position, to increase contact between the second cleaning member and the roller assembly.

Preferably, the rotation of the at least one roller assembly is driven by a motor when the cleaning assembly is in its first position. This may be affected by a motor dedicated to the sensing apparatus or by one forming part of a larger transport mechanism. Advantageously, the rotation of the at least one roller assembly is driven manually when the cleaning assembly is in its second positions. However, as noted above this too could be driven by a motor.

An example of a sheet sensing apparatus in accordance with the invention will now be described with reference to the accompanying drawings, in which:-

Figure 1 is an exploded view of the main components of a first embodiment of a sheet sensing apparatus in accordance with the invention;

Figure 2 shows the components of a sensing arrangement used in the embodiment of Figure 1 ;

Figure 3 is a cross-section through the assembled sheet sensing device; Figure 4 is a schematic view of a cleaning assembly used in the embodiment of Figure 1;

Figure 5 shows two cleaning assemblies in situ;

Figure 6 is a schematic cross-section showing a cleaning assembly in its first position;

Figure 7 is a schematic cross-section showing a cleaning assembly in its second position;

Figure 8 is a perspective view of a cleaning assembly for a second embodiment of a sheet sensing apparatus in accordance with the invention; and Figure 8A shows the cleaning assembly of Figure 8 in exploded view.

In this example, the sheet sensing device is of the type disclosed in EP-A- 0130824. However, as noted above, the features of the invention may be used advantageously in conjunction with any sheet sensing technique which relies on detecting a change in spacing between a roller assembly and a guide.

The main components of a first embodiment of the sheet sensing apparatus are shown in Figure 1 in exploded form. The components are assembled on a shaft 1 which is mounted into the framework of a document handling machine, such as a banknote counter. For example, the sheet sensing apparatus or "doubles detector" could be employed in a banknote counter such as that disclosed in British patent application number 0612856.5. Two roller assemblies 6a and 6b are rotatably mounted on the shaft 1, spaced laterally along the shaft axis. In the embodiment shown in Figure 1, the shaft 1 is provided with recesses 3a and 3b within which the roller assemblies 6 are located.

Two cleaning assemblies 30a and 30b are provided for clearing dirt and dust from the roller assembly 6a and 6b in use. In this example, the cleaning assemblies 30a and 30b are joined by a beam 40, so as to form a single component. The cleaning assemblies will be described in greater detail below. When the document handling machine is assembled, the two roller assemblies 6a and 6b oppose a guide surface so as to find a nip therebetween through which documents such as banknotes pass in use. In this example, the guide surface is provided by two guide rollers 20a and 20b, depicted in Figure 3. The guide rollers 20 and roller assemblies 6 are spaced apart by a distance less than the thickness of the sheets being sensed.

At least a portion of the shaft 1 is hollow. In the present embodiment, the shaft 1 has a solid bore which is locally hollowed out from the back (not shown) to accommodate optosensor assemblies 10a and 10b. The interior of the shaft 1 is accessed via removal plates 7, which is affixed using screws 8.

Each roller 6 comprises a roller bearing having an annular outer race 17, an annular inner race 19 and bearings 18 positioned between the inner and outer races (see Figure 3). The bearing is mounted coaxially about the shaft 1 on a resilient portion 4, typically made of rubber. This rubber portion may be annular

(as shown in Figure 3) or may surround only a portion of the shaft 1 toward the opposing guide rollers 20 (as shown in Figure 1). A pin 5, typically made of plastic, abuts the radially inner surface of the inner race 19 and extends through the rubber portion 4 and an aperture 15 provided in the shaft 1, so as to protrude into the shaft.

A molded plastics housing 12 is mounted within the shaft 1. This housing 12 may be provided in the form of a single molding extending between both roller assemblies 6a and 6b, in which case it comprises a central tubular portion 12c integral with end portions 12a and 12b, each of which have a bore 16a and 16b communicating with a tubular portion 12c. Alternatively, as shown in Figures 1 and 2, the plastics housing 12 may be provided in the form of two separate components 12a and 12b making up part of the optosensor assemblies 10a and 10b (Figure 2), and the central tubular portion 12c may be omitted. Each component 12a and 12b is mounted on a plate 9a and 9b, on base 7, for ease of removal.

In the optosensor assemblies 10, a pair of light emitting diodes 13a and 13b are mounted in the inner end of the bores 14a and 14b, while a pair of phototransistors 11a and 11b are mounted at the other end of the bores 14. For clarity, only portions of the connecting wires from the light emitting diodes and the phototransistors have been illustrated. In fact, these wires will pass along and out of the shaft 1 to monitoring circuitry. To facilitate assembly, all wires extend from the same end of the shaft 1. Each portion 12a and 12b of the housing also has an aperture 16a and 16b communicating with the bore 14a and 14b in alignment with the aperture 15a and 15b respectively. The pins 5a and 5b extend through the apertures into the bores 14a and 14b.

In use, banknotes B (or other documents) are fed by a transport system (not shown) into the nip N formed between the roller assemblies 6 and the guide rollers 20 (see Figure 3). The banknote B will be fed between the guide rollers 20 and the roller assembly 6 by rotation of the shaft 21 on which the guide rollers 20 are fixedly mounted. Typically, the guide rollers 20 each have an outer annular portion 22a and 22b made of rubber to ensure friction between the guide rollers 20 and the banknote B, so as to move the banknote B through the nip N. The roller assemblies 6 turn freely as the banknote B passes.

Each LED 11 continuously emits light which impinges on respective phototransistors 13, causing each phototransistor to pass collected current at an initial level. Each pin 5 normally partially obscures the light path. When a banknote B is presented to the nip N between the guide rollers 20 and the respective roller assembly 6, the banknote B will be taken up and transported through the nip and each rubber portion 4a and 4b will be compressed radially inwardly due to pressure exerted from the outer race 17 via the bearings 18 and the inner race 19. This movement will also be accompanied by a radially inward movement of each pin 5a and 5b, which will thus further obscure the path of optical rays from the LEDs to the phototransistors, thereby further attenuating light transmitted to the phototransistors.

Changes in the light intensity received by the phototransistors 13 are detected by a monitoring circuit (not shown) and compared with preset thresholds to determine whether one or more banknotes have passed through the nip. A suitable circuit arrangement and details of appropriate processing techniques are detailed in EP-A-0130824 and British patent application number 0612856.5. The outputs can be used to detect whether a single banknote has passed though the nip, or, if the sensed deflection corresponds to a multiple note thickness, whether two or more notes have passed. It is also possible to detect folded banknotes (where the output from one roller assembly 6a differs from that from the other roller assembly 6b), and torn or skewed notes. It is also possible to detect the note length in the direction of travel by monitoring the time over which the note is detected in the nip and having knowledge of the transport speed.

To ensure that the thickness of a passing document is determined accurately by the apparatus, it is important to ensure that the nip N between the guide wheels 20 and the roller assemblies 6 remains clean and clear of any foreign objects. For this reason, a cleaning assembly 30a and 30b is provided to cooperate with each of the roller assemblies 6 to prevent the build-up of dust or dirt on its surface.

One of the cleaning assemblies 30 is shown in Figure 4. The assembly 30 comprises two cleaning members: a first in the form of a brush 31 and a second in the form of a scraper 32. In other examples, two brushes or two scrapers could be employed. The brush 31 and scraper 32 are joined by a support member 33, which in this example is integral with the scraper 32. The support 33 and/or scraper 32 are preferably made of a resilient material such that the scraper may be urged against the roller assembly 6 in use to exert pressure thereon and remove stubborn dirt deposits. The cleaning assembly 30 can be constructed by molding the scraper and support structure 32/33 out of a plastics material and providing features to locate a brush 31. The brush is typically made of polymer fibre such as nylon, but could be replaced by a wire brush if desired.

The two cleaning assemblies 30a and 30b are conveniently supported on a beam 40 which may also be integrally molded with the supports 33. The beam 40 may be used to secure the cleaning assemblies 30 to the framework of the machine (indicated as component 50 in Figure 5) via bolts or screws 41. By co- locating the cleaning assemblies on beam 40, a single part construction is provided, and the two assemblies are constrained to move in unison.

The portion of the framework 50 onto which the cleaning assemblies 30 are mounted is preferably moveable relative to the roller assemblies 6. In this example, the document handling machine is such that the roller assemblies 6 are mounted into a static base structure of the machine (not shown), whereas the framework 50, onto which the cleaning assemblies 30 are mounted, forms part of a cover structure which is moveable relative to the base structure. For example, in the banknote counter disclosed in British patent application number 0612856.5, the framework 50 forms part of the detector box, which in normal use is "closed" (i.e. it abuts the base structure), but can be opened for access to the transport path.

Figure 6 shows a cross-sectional view of the cleaning assembly 30 in a first position. The first cleaning member 31 , in this case a brush, contacts the surface of roller 6. The cleaning member 30 is mounted via cross piece 50 onto cover structure 52 which itself is pivotally mounted to the base structure of the machine at pivot point 51. The direction of travel is indicated by the arrow T. In use, a banknote is guided by guide plates 50 into the nip N between roller assembly 6 and guide roller 20. Rotation of the guide roller 20 draws the banknote through the nip N and rotates the roller assembly 6. The brush 31 sweeps the surface of the roller 6 as it passes, clearing any dust or debris which the roller may have picked up from the passing banknote.

During this stage, as indicated above, rotation of the roller 6 is effected by the transport mechanism in the document handling machine itself.

When the cover structure 52 of the document handling machine is opened by pivoting it relative to the base structure about pivot point 1 , the user has access to the machine interior. As the cover structure 52 rotates from position i to position ii, the first cleaning member 31 is moved away from the roller 6, and the second cleaning member 32, in this case a scraper, is brought into contact with the surface. It should be noted that the angles at which the first and second cleaning elements 31 and 32 contact the surface of the roller 6 may be different from each other, as in the present example, and are preferably each optimised for efficient cleaning. For example, it is preferable that a brush component would form an acute angle with the surface of the roller, with the brush bristles facing downstream so as to avoid damage. In contrast, a scraper element preferably sits at an angle facing the oncoming roller surface, as shown in Figure 7. The particular angles can be selected by appropriate molding of the support member 33. With the cleaning member 30 in the second position, the roller 6 must still be rotated in order to effect cleaning. Since the document handling machine is open, the normal note path is disengaged. There are a number of options by which the roller 6 may now be rotated.

In a first example, the apparatus may be provided with manual drive means for rotating the roller 6, such as a hand wheel. These may, for example, only come into engagement when the cover 52 is moved into its open position. Preferably, however, the rotation is still carried out via guide rollers 20 acting on roller assembly 6. In other cases, the user could simply manually turn either the roller assembly 6 or guide rollers 20 directly.

Alternatively, a motor could be used to drive rotation of the roller assembly 6 in this open position. Typically, the transport motor used in normal operation of the machine is powerful and may present a safety hazard if the user were to operate the rollers using this motor with the system open. One option is therefore to provide a secondary, less powerful motor which is dedicated for driving the roller assembly 6 in the second position for cleaning. Another alternative would be to utilise the note transport motor of the document handling machine via a control which operates the motor at a reduced speed or a gearing system having the same function.

Where the roller rotation is driven, the apparatus may further include a controller which drives the rotation of the roller 6 in accordance with a predetermined program. For example, sensors could be used to detect the opening of the cover structure 52. This action can be sensed by the controller and used to initiate drive of the guide rollers 20, thereby rotating the roller assembly 6 for the period while the operator holds the cover structure 52 open.

In the second position, the scraper 32 effectively acts as a stop which prevents the cover structure 52 from opening any further. By utilising a resilient material as the support member 33 and/or scraper 32, by pushing the cover structure 52 back further against the resilient spring of the scraper 32, the user can apply more pressure against the rollers from the scraper 32, in order to clear the most stubborn deposits.

The described "one piece" construction of the cleaning assembly means that it can be easily fitted to and dismantled from the document handling machine. Further, the cleaning assembly can easily be replaced, when necessary, during service with little disassembly and reassembly required.

A cleaning assembly for a second embodiment of the invention is shown in Figures 8 and 8A. Here, the two cleaning assemblies 60a and 60b are integrated with one another forming a unit 60. In contrast the first embodiment, in which the two cleaning assemblies 30a and 30b are joined by a beam 40, here, the two cleaning assemblies 60a and 60b are joined by means of an integral support member 62/63 and share a common first cleaning member 61. Thus each cleaning assembly 60a and 60b comprise a first cleaning member 61a and 61b which are in fact portions of a single cleaning member 61 extending laterally between the two cleaning assemblies. The cleaning member 61 is mounted in (or made from an integral part of) a support member 63 which also runs naturally between the two cleaning assemblies. Each end 63a and 63b acts as the support member for the respective cleaning assemblies 60a and 60b. This is affixed via bolts 64a and 64b through holes 65a and 65b to the second cleaning members, joined in this case by a cross piece 62. The second r.leaninα members 62a and 62b are integral extensions of the cross piece 62.

As in the first embodiment, the second cleaning members 62a and 62b are scrapers, and are preferably resilient. The first cleaning member 61 is preferably a brush but could alternatively be a flexible wiping blade performing substantially the same function.

The rest of the sheet sensing device is preferably the same as described in relation to the first embodiment, and the cleaning assembly 60 can be fitted to a note handling machine in much the same way as shown in Figures 5-7.

By providing a cleaning assembly having first and second cleaning members in this way, it is possible to maintain the cleanliness of the sheet sensing apparatus without causing undo wear to the rollers or cleaning components. In particular, brushes (used in this example as the first cleaning member) have been tested for wear and after the equivalent of 75 million note passes, although in a fairly clean environment, there was no noticeable wear on the brushes. As such, even in a dirty environment, the brushes are expected to last at least between standard service intervals of up to 20 million notes. Testing during field trials has shown the cleaning device to be very effective.

Claims

1. Sheet sensing apparatus comprising a shaft, at least one roller assembly mounted on the shaft, a guide surface, the at least one roller assembly cooperating with the guide surface to define a nip therebetween, sensing means for sensing deflection of the at least one roller assembly relative to the guide surface in response to the passage of one or more sheets through the nip, monitoring means connected to the sensing means for monitoring the sensed deflections of the at least one roller assembly, and at least one cleaning assembly arranged to cooperate with the at least one roller assembly, the at least one cleaning assembly comprising a first cleaning member and a second cleaning member, wherein the cleaning assembly is movable between a first position in which the first cleaning member contacts the roller assembly whilst the second cleaning member is spaced from the roller assembly, and a second position in which the second cleaning member contacts the roller assembly.

2. Sheet sensing apparatus according to claim 1 wherein, in the second position, the first cleaning member is spaced from the roller assembly.

3. Sheet sensing apparatus according to claim 1 or claim 2 wherein the cleaning assembly comprises a support member on which the first and second cleaning members are mounted, the support member being movable relative to the at least one roller assembly.

4. Sheet sensing apparatus according to claim 4 wherein the support member is pivotable.

5. Sheet sensing apparatus according to claim 3 or claim 4 wherein at least one of the first and second cleaning members is an integral part of the support member.

6. Sheet sensing apparatus according to any of claims 3 to 5 wherein the support member is of a resilient material.

7. Sheet sensing apparatus according to any of the preceding claims wherein the first cleaning member comprises a brush.

8. Sheet sensing apparatus according to any of the preceding claims wherein the second cleaning member comprises a scraper.

9. Sheet sensing apparatus according to any of the preceding claims further comprising means for rotating the at least one roller assembly about the axis of the shaft.

10. Sheet sensing apparatus according to claim 10 wherein the means for rotating the at least one roller assembly are manual, and preferably comprise a handwheel for operation by a user.

11. Sheet sensing apparatus according to claim 10 wherein the means for rotating the at least one roller assembly are driven, and preferably comprise a motor.

12. Sheet sensing apparatus according to claim 11 further comprising a controller adapted to control the means for rotating the at least one roller assembly in accordance with a predetermined program.

13. Sheet sensing apparatus according to any of the preceding claims wherein the guide surface comprises at least one guide roller opposing the at least one roller assembly.

14. Sheet sensing apparatus according to claim 14 and any of claims 10 to 13 wherein the means for rotating the at least one roller assembly comprise the at least one guide roller.

15. Sheet sensing apparatus according to any of the preceding claims wherein the at least one roller assembly is mounted on the shaft by means including a resilient portion, such that deflection of the at least one roller assembly relative to the guide surface cause deflection of the resilient portion relative to the shaft, and the sensing means sense deflection of the resilient portion to determine deflection of the at least one roller assembly.

16. Sheet sensing apparatus according to claim 15 wherein the sensing means are disposed within the shaft.

17. Sheet sensing apparatus according to claim 16 wherein the at least one roller assembly includes a rigid member protruding into the shaft, the rigid member being radially movable relative to the shaft in response to deflections of the resilient portion and cooperating with the sensing means.

18. Sheet sensing apparatus according to claim 17, wherein the sensing means includes means for generating and receiving electromagnetic radiation, the material of the rigid member being such that on deflection of the resilient portion, the proportion of electromagnetic radiation received by the receiving means varies due to movement of the rigid member.

19. Sheet sensing apparatus according to claim 18, wherein the generating means comprises one or more light emitting diodes, and the receiving means comprises a phototransistor.

20. Sheet sensing apparatus according to any of the preceding claims, wherein the monitoring means includes detection means for detecting whether deflection of the resilient portion is caused by the passage of one or of more than one sheet through the nip.

21. Sheet sensing apparatus according to any of the preceding claims, wherein the at least one roller assembly comprises inner and outer races surrounding bearing means, the inner race being coaxial with the shaft and being supported on the shaft by the resilient portion.

22. Sheet sensing apparatus according to claim 21 when dependent on any of claims 17 to 19, wherein the rigid member comprises a pin abutting an inner surface of the inner race and protruding through an aperture in the shaft.

23. Sheet sensing apparatus according to any of the preceding claims wherein the sensing means is mounted in a housing which is slidable into and out of the shaft.

24. Sheet sensing apparatus according to any of the preceding claims, comprising two roller assemblies mounted on the shaft and spaced from each other.

25. Sheet sensing apparatus according to claim 24, comprising two cleaning assemblies, each cooperating with a respective one of the roller assemblies.

26. Sheet sensing apparatus according to claim 25 wherein the two cleaning assemblies are fixed relative to one another such that they move simultaneously between the first and second positions.

27. Sheet sensing apparatus according to claim 26 wherein the two cleaning assemblies are integrally formed with one another.

28. Banknote handling apparatus comprising sheet sensing apparatus according to any of the preceding claims.

29. Banknote handling apparatus according to claim 28 further comprising a base structure, to which the shaft is fixed, and a cover structure movable relative to the base structure, to which the at least one cleaning assembly is fixed.

30. Banknote handling apparatus according to claim 29 wherein the cover structure is pivotably mounted to the base structure at a pivot point such that the cover structure is movable between a closed position in which the cover structure abuts the base structure, and an open position in which the cover structure is spaced from the base structure away from the pivot point.

31. Banknote handling apparatus according to claim 30 wherein the at least one cleaning assembly is in its first position when the cover structure is in its closed position, and the cleaning assembly is in its second position when the cover structure is in its open position.

32. Banknote handling apparatus according to any of claims 29 to 31 wherein the cover structure supports one or more detectors for detecting characteristics of banknotes passing through the banknote handling apparatus.

33. A method of cleaning a sheet sensing apparatus comprising a shaft and at least one roller assembly mounted on the shaft, the method comprising: positioning a cleaning assembly having a first cleaning member and a second cleaning member in a first position such that the first cleaning member contacts the roller assembly whilst the second cleaning member is spaced from the roller assembly; rotating the at least one roller assembly about the shaft axis such that the first cleaning member acts against the moving surface of the roller assembly; moving the cleaning assembly into a second position in which the second cleaning member contacts the roller assembly; and rotating the at least one roller assembly about the shaft axis such that the second cleaning member acts against the moving surface of the roller assembly.

34. A method according to claim 33 wherein, in the second position, the first cleaning member is spaced from the roller assembly.

35. A method according to claim 33 or 34 wherein the step of moving the cleaning assembly comprises pivoting a support member on which the first and second cleaning members are mounted.

36. A method according to claim 35 wherein the support member is resilient.

37. A method according to any of claims 33 to 36, further comprising the step of applying pressure to the second cleaning member when the cleaning assembly is in the second position, to increase contact between the second cleaning member and the roller assembly.

38. A method according to any of claims 33 to 37 wherein the rotation of the at least one roller assembly is driven by a motor when the cleaning assembly is in its first position.

39. A method according to any of claims 33 to 38 wherein the rotation of the at least one roller assembly is driven manually when the cleaning assembly is in its second position.

40. A method according to any of claims 33 to 39 wherein the first cleaning member is a brush.

41. A method according to any of claims 33 to 40 wherein the second cleaning member is a scraper.