WO2008122745A1

WO2008122745A1 - Document handling apparatus

Info

Publication number: WO2008122745A1
Application number: PCT/GB2007/001319
Authority: WO
Inventors: Simon Calverley
Original assignee: Talaris Holdings Limited
Priority date: 2007-04-05
Filing date: 2007-04-05
Publication date: 2008-10-16
Also published as: TW200919378A

Abstract

A document handling apparatus (1) is disclosed, comprising a document path (NP) through the apparatus, a transport assembly (10) for conveying a document along the document path, and a magnetic detector device (20) adjacent at least a portion of the document path for detecting magnetic material in passing documents. The transport assembly comprises at least one rotatable member, which comprises ceramic material.

Description

Document Handling Apparatus

This invention relates to a document handling apparatus, in particular document sorters or counters in which documents passing therethrough need to be identified or authenticated. The invention is particularly well-suited to the handling of documents of value such as banknotes, certificates, cheques etc. which may be equipped with a number of security features verifying the authenticity and/or denomination of the document. In particular, the apparatus is adapted for detecting magnetic security features in such documents.

The use of magnetic detectors to sense and "read" magnetic features in documents such as banknotes is well-known and has been described in, for example, EP-A- 1221679, EP-A-1353301 and EP-A-1353302. A number of different magnetic sensors are described in British patent application number 0612856.5.

Commonly, documents such as banknotes may be equipped with a number of features containing magnetic material, such as a thread embedded into the document substrate or printed matter utilising magnetic ink. For example, on banknotes it is known to print the serial number using a magnetic ink. Such magnetic features may include coding. That is, in the example of a magnetic thread, the thread may consist of magnetic and non-magnetic portions in sequence, the arrangement of segments constituting a code.

In its most basic form, a magnetic detection device may simply comprise a means such as a wire coil and a monitoring circuit for detecting the presence of a magnetic field. For example, where a passing banknote contains magnetised material, as the material passes close to the magnetic detector, the moving magnetic field will induce a current in the coil which can be monitored and used to determine the presence of the magnetic feature. In more sophisticated devices, the detector may additionally include means for generating a magnetic field such that magnetic (but non-magnetised) material in a passing document can be magnetised and so detected by the field detecting means. Such document handling systems typically use a transport assembly consisting of rollers and/or belts to move each document past the magnetic detector and other sensors and through the rest of the machine where it is dealt with in a manner which may be dependent on the output signal from the detectors. In an effort to make the machines more compact, it is often necessary to provide a number of transport rollers in close proximity to the detectors. The rollers are either driven by a transport motor so as to convey the document along the document path through the machine, or free-wheel in response to the passage of a document.

In most cases, transport rollers are made of plastics materials in order to have a surface of sufficiently high friction so as to transfer drive to the documents.

However, for certain functions in the transport system it has been found advantageous to use rollers having a hard wearing, smooth surface. Conventionally, in these cases the rollers are made of metal, usually steel, because the surface is hard wearing, the component is low-cost, they are readily available and have a long lifetime. A particular example is the roller assemblies used in a doubles detector device for counting passing documents. Such assemblies are described in EP-A-0130824 and British patent application number 0612856.6, amongst others. In such assemblies, the roller typically comprises a metallic bearing assembly having inner and outer races and intervening metallic ball bearings. -

It has been found that the rotation of such metallic rollers can interfere with the operation of magnetic detectors, since the roller itself possesses a magnetic signature which can, if the roller is situated too close to the magnetic detector, be sensed and distort the output signal from the magnetic head. As a result, it has proved necessary to deal with this problem either by positioning such moving metallic parts a long way from any magnetic detector, thereby increasing the overall size of the apparatus, or by providing magnetic shielding between such rotating parts and the magnetic sensors which is cumbersome and expensive.

In accordance with a first aspect of the present invention, a document handling apparatus comprises a document path through the apparatus, a transport assembly for conveying a document along the document path, and a magnetic detector device adjacent at least a portion of the document path for detecting magnetic material in passing documents; wherein the transport assembly comprises at least one rotatable member, the rotatable member comprising ceramic material. 5

By making the rotatable member (preferably entirely) from a ceramic material, the component has mechanical properties which compare favourably with those of metal. Unlike plastic, the surface is hard-wearing and the ceramic component therefore has a long lifetime. However, since the material cannot be magnetised

10 and also cannot conduct electricity, rotation of the component does not interfere with the signal obtained from a magnetic detection device in the proximity of the rotatable member. As such, it becomes possible to position such rotatable members close to magnetic detectors without compromising the ability of the magnetic sensor to authenticate or identify passing documents. As a result, there

15 are no constraints on the relative position of the magnetic detector device and the rotatable member, allowing the apparatus to be made compact.

Preferably, the ceramic material is zirconia (ZrO₂).

20 The rotatable member could be a roller, a wheel or a bearing, or indeed any other rotating part which could otherwise have an effect on the magnetic detector device.

__ — — For-instønee,-the-cerami&-rotatable member could be a transport roller or wheel defining at least a point on the document path, or a bearing, used for example to mount a rotating shaft in a framework of the apparatus.

25

In a preferred embodiment, the at least one rotatable member is mounted on a shaft within the document handling apparatus. In some cases, the at least one rotatable member is fixedly mounted to the shaft and the shaft is driven so as to rotate the rotatable member. Alternatively, the at least one rotatable member is

30 rotatably mounted to the shaft and is rotated by the passage of passing documents.

In a particularly preferred embodiment, the at least one rotatable member forms part of a sheet sensing assembly for detecting the passage of documents through the apparatus. By making the rotatable parts of the sheet sensing assembly out of ceramic material in this way, the sheet sensing assembly can be mounted close to the magnetic detector device, without the need for magnetic screening.

In accordance with a second aspect of the invention, a document handling apparatus comprises a document path through the apparatus, a transport assembly for conveying a document along the document path, and a magnetic detector device adjacent at least a portion of the document path for detecting magnetic material in passing documents; wherein the transport assembly comprises a sheet sensing assembly for detecting the passage of documents through the apparatus having at least one rotatable member, the rotatable member comprising nonmagnetic material.. By making the rotatable member(s) of a sheet sensing apparatus (doubles detector) out of a non-magnetic material such as plastic, rubber or a non-magnetic metal, it is possible to position the doubles detector in close proximity to the magnetic detection device, i.e. within the region in which magnetic fields can be sensed by the magnetic detection device.

Advantageously, in the first or second aspects of the invention, the sheet sensing assembly further comprises a shaft on which the at least one rotatable member is rotatably mounted; a guide surface cooperating with the at least one rotatable member to define a nip therebetween, sensing means for sensing deflection of the at least one rotatable member relative to the guide surface in response to the passage of one or more sheets through the nip and monitoring means connected to the sensing means for monitoring the sensed deflections of the at least one rotatable member. Such mechanical "double detector" configurations have been found to be particularly effective at detecting the passage of a document, and identifying overlapping sheets.

Preferably, the guide surface comprises at least one guide roller opposing the at least one rotatable member, In other examples, the guide surface could be provided by guide plates or guide fingers.

Preferably, the at least one rotatable member is mounted on the shaft by means including a resilient portion, such that deflection of the at least one rotatable member relative to the guide surface causes 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 rotatable member. This configuration has been found to be particularly accurate and has the added advantage that the sensing means may be disposed within the shaft, thereby protecting it from dirt and mechanical damage.

Preferably, the means mounting the at least one rotatable member onto the shaft further 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. Conveniently, the sensing means includes means forgenerating 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. Preferably, the generating means comprises one or more light emitting diodes, and the receiving means comprises a phototransistor.

Preferably, the at least one rotatable member 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. It is preferred that each of the inner and outer races as well as the bearing means are made of ceramic material.

Advantageously, the rigid member comprises a pin abutting an inner surface of the inner race and protruding through an aperture in the shaft.

Preferably, the sheet sensing apparatus comprises two rotatable members mounted on the shaft and spaced from each other. It is preferred that both rotatable members be made of ceramic.

Preferably, the magnetic detector device comprises at least one magnetic head disposed adjacent to the document path, the at least one magnetic head being adapted to generate a signal upon detecting magnetic material in a passing document. Advantageously, the at least one magnetic head is an inductive magnetic head or a magnetoresistive magnetic head.

In a first preferred embodiment, the at least one magnetic head is an active head and comprises magnetic field generating means for magnetising any magnetic material in a passing document, and magnetic field sensing means for detecting changes in the generated magnetic field caused by magnetic material in a passing document. Alternatively, the at least one magnetic head is a passive head and comprises magnetic field sensing means for detecting a magnetic field resulting from magnetised material in a passing document.

In a particularly preferred embodiment, the magnetic detector device comprises two magnetic heads, the first an active head and the second being a passive head comprising magnetic field sensing means for detecting a magnetic field resulting from magnetised material in a passing document.

In another preferred embodiment, the magnetic detector device comprises an array of magnetic heads each of which is connected to a respective processor which processes signals generated by the associated magnetic head, and a processing system connected to the processors.

\4vantageously,-the-pr.ocessing system is adapted to, upon relative movement between a document containing a magnetic material and the array of magnetic heads, detect the arrival of the magnetic material at one of the heads and denote that a primary head, and the head on each side a secondary head; thereafter monitor output signals from the primary and secondary heads to generate a representation of the magnetic material, and compare the magnitude of the signals from the primary and secondary heads such that if the magnitude of the output signal from a secondary head exceeds that from the primary head, the primary and secondary heads are reallocated accordingly.

Any other detector arranged to detect magnetic material may be used instead.

Preferably, the magnetic material in the passing document is a thread. Advantageously, the document handling apparatus is adapted to handle documents of value, preferably banknotes. Preferably, the document handling apparatus further comprises a controller adapted to determine whether each document of value is authentic, or to identify a characteristic of each document of value, based on the output from the magnetic detector device.

An example of a document handling apparatus in accordance with the present invention will now be described with reference to the accompanying drawings in which:-

Figure 1 is a cross-section through an embodiment of a document handling apparatus in accordance with the present invention;

Figure 2 is an exploded diagram showing components of a magnetic detector device for use in the embodiment of Figure 1 ; Figure 3 shows an exploded diagram of an alternative magnetic detector device for use in the embodiment of Figure 1 ;

Figure 4 is an exploded diagram showing a doubles detector arrangement for use in the embodiment of Figure 1 ;

Figure 4a shows a detector arrangement used in the doubles detector device of Figure 4; and

Figure 5 is a cross-section through a doubles detector device.

The following description will focus on the example of a banknote handling machine, such as a banknote counter or sorter. However, it will be appreciated that the present invention can be employed in many types of document handling apparatus. Nonetheless, the invention is particularly well suited to applications wherein the documents are required to be authenticated or otherwise identified by the apparatus.

Figure 1 shows a cross-section through a portion of a banknote handling apparatus. In this example, the apparatus is similar to that disclosed in British patent application number 0612856.5, used to count banknotes. A stack of banknotes is fed into the apparatus 1 via an input area 2. The banknotes are fed one by one through the banknote apparatus 1 along note path NP. The banknotes are output into output area 3 where a stack can be formed for presentation to the user.

The banknotes are conveyed along the note path NP by a transport assembly generally designated 10 in Figure 1. The transport assembly 10 consists of a number of transport wheels or rollers 11 , 12 and 13 mounted within the apparatus on corresponding shafts 11a, 12a and 13a. A series of guide plates 16 and 17 define either side of the note path NP to direct notes between the rollers. Means are also provided to help separate the stack of banknotes such that a single note is fed at a time. In this case, such means include a rubber block 15. The transport means may also include free-wheeling rollers such as roller 14 to assist in guiding the banknotes along the note path.

Transport rollers such as 11 , 12 and 13 depicted in Figure 1 are generally made of plastics material and may include an outer rubber layer, or portion thereof, to ensure that there is sufficient friction between the roller and the banknote so as to impart drive. In contrast, free-wheeling rollers such as roller 14 in Figure 1 are generally made of a hard-wearing material, in this case preferably ceramic.

The transport assembly conveys notes along the note path past one or more detectors such as device 20 in Figure 1 which is a magnetic detector. The apparatus may-alscLindud.ejipJLc.aLdeiej:tρis_sMch_as IR or UV detectors as well as tracking sensors and size detectors as described in British patent application number 0612856.5.

The magnetic detector 20 is used to detect any magnetic material occurring in the passing banknotes. The detector 20 consists generally of one or more magnetic heads 21 which generate a signal in the presence of a magnetic field. A roller 22, typically made of foam, is used to press the passing banknote against the magnetic head 21 to ensure good coupling. The signals generated by the magnetic head 21 are processed by a PCB 23.

Ih apparatus which are used to count or identify documents, it may be necessary to detect overlapping documents or the dimensions of passing documents. In the present example, this is achieved using a mechanical doubles detector arrangement designated 30 in Figure 1. This consists essentially of one or more free-wheeling rollers 31 mounted on a shaft 32 via a resilient portion 33. Deflection of the roller 31 relative to the shaft 32 is sensed, in this case by measuring the corresponding deflection of the resilient portion 33, to give an indication of whether a single banknote has passed, or whether the banknote is overlapped, folded or otherwise.

The doubles detector roller 31 , conventionally made of metal, in the present case is instead made of ceramic. As a result, rotation of the roller 31 has no effect on the signal output by adjacent magnetic heads 21. This is because the nonmagnetic ceramic material is not capable of generating or otherwise affecting a magnetic field in its locality, and as such it does not contribute to the magnetic field detected by the magnetic detector device 20.

Where non-conducting materials such as ceramics are used, there is a possibility that static charge could build up on the component due to its interaction with passing documents and other moving or stationary components. If allowed to build up unchecked, the static could discharge as a spark which could interfere with a nearby magnetic detector. In view of this, it is preferred that the ceramic components are designed to direct any discharge away from the magnetic head.

If the free-wheeling transport roller 14 is also made of ceramic, then this component also will not interfere with the magnetic detector device 20. Suitable ceramic rollers or bearings can be obtained from various suppliers including Carter Manufacturing Company, Inc. (Ml, USA) or Shanghai Lily Bearing Manufacturing Co. Ltd (Shanghai, China).

Figure 2 shows a first example of a magnetic detector device 20 and shows how it would be assembled within the document handling apparatus of Figure 1. In this example, the magnetic detector device is an enhanced magnetic presence detector (EMG). The EMG detector provides a method of determining whether a banknote has any magnetic material contained within it. The detector head 21 is mounted within a plastic housing 21a within guide plate 16. In this example, the detector head 21 is centred but in other embodiments it could be positioned laterally anywhere along the note path NP. A plurality of such assemblies 21 could be provided to give better note coverage. The detector is connected to a control PCB 23 mounted via a plate 23a to the rear of guide plate 16. The detector may have a ceramic coating to increase durability of the magnetic heads.

The assembly 21 comprises two inductive heads which measure different magnetic qualities of the banknote. The first head is an active head containing means for generating a magnetic field, such as a coil through which a current is applied. If the passing banknote contains magnetic material, this is magnetised by the active head and generates its own magnetic field, thereby altering that produced by the detector head. This change of magnetic field is detected by circuitry within the head acting as means for sensing a magnetic field. The measured change in magnetic field can be used to determine whether or not the banknote is genuine.

The second head is a passive head which does not contain means for generating a magnetic field. Instead, the head simply includes means for measuring local magnetic fields and thus detects any magnetic field that remains due to magnetised material in the banknote which may continue after the magnetic field generated by the first head is decayed. The signals are then transmitted to the PCB 23 to be used as a measure of authenticity. Typically, authenticity is determined using calculations-based on-a-ratio-of the-raeasurement of the first, active head and the second, passive head. The ratiometric measurement can be compared with respective measurements for known banknotes stored in the memory or alternatively by comparing the measured level with a threshold. In alternative modes of operation, only one of the heads may be functional to allow the detection of magnetic material without distinguishing between induced magnetism and residual magnetism.

The passing banknotes are maintained in close proximity to the magnetic head 21 by use of a roller 22 mounted in a support bracket 22a, only the back of which is visible in Figure 2. An alternative magnetic detection device 20' is shown in Figure 3. This is a superior magnetic detector system (SMDS) and is used to check for the presence of a security thread in the passing banknote and to read information coded within the thread. The thread may be a simple metallic thread or it may comprise segments of magnetic material and segments of non-magnetic material. The segments of magnetic and non-magnetic material may be arranged such that they represent a code. For example, the segments may be arranged into fixed length elements so that they represent a binary word and this word may be repeated several times along the thread. In one examples, the fixed length elements may have a length of two millimetres, the presence of magnetic material indicating a binary 1 and the absence indicating a binary 0.

The SMDS detector is shown in exploded form in Figure 3. A magnetic head assembly 21' is attached to a processing PCB 23' and the two items fit into an aperture 21 a" within plastic moulding 21a. When assembled, the plastic moulding 21a' can be fixed to the edge of guide plate 16 shown in Figures 1 and 2 so as to form part of the guide surface through the apparatus. An earthing rod 25' is also provided. The magnetic head assembly 21 ' comprises an array of magnetic heads which cover the majority of the passing banknote. A code within the magnetic thread may be read by temporarily magnetising the material and arranging for the banknotes to be carried by the transport mechanism 10 such that they pass by the array of magnetic heads 21' in close proximity. Each of these heads will generate a signal upon detecting a magnetic material.

Typically, the magnetic head assembly 21 ' comprises a plurality of magnetic heads, conveniently twelve, arranged transversely to the transport pathway NP. After a note has passed the array of heads by a small amount, a primary head is designated by the detection of the signal corresponding to a thread. One or more secondary heads are also designated on one or both sides of the primary head. Output signals from the primary and secondary heads on one or both sides are monitored to generate a representation of the thread, and the magnitude of the primary and secondary signals are compared such that if the magnitude of the output signal from the secondary head exceeds that from the primary head, the primary and secondary heads are reallocated accordingly. Since the code on the thread is typically non-symmetrical and digitisation starts before the end of the note, it is possible to know the denomination, facing and orientation of the note very soon after the note has reached the detector.

5 In parallel, all the channels may be recorded to allow a magnetic image of the note to be captured. Positions on the note can then be checked for both absence and presence of magnetic features such as serial number ink as predicted by the facing, orientation and denomination information already determined from the coded thread. The orientation and/or facing can also be determined from the position of0 the serial number. This allows advanced authentication and denomination pattern matching.

Further examples of systems using the SMDS principles can be found in European patent applications 1221679, 1353301 and 1353302 as well as British patent5 application number 0612856.5.

In this example, the document handling apparatus 1 is also provided with a sheet sensing apparatus 30, also known as a doubles detector. In apparatus not requiring accurate counting of the documents, this device may be omitted. The main0 components of the doubles detector 30 are shown in Figure 4. At least one roller assembly 31 a, 31 b is rotatably mounted on a shaft 31. In this example, there are

— - — ^two-r&ller--assemblies^J3_ancL3JjDjs.p3^edJaterally along the shaft 32. The shaft 32 is provided with recesses 34a and 34b within which the roller assemblies 31a and 31b are located. When assembled into the apparatus, the roller assemblies 5 31a and 31b are opposed by two drive wheels 13, one of which is shown in Figure 1. The drive wheels 13 provide a guide surface which together with the rollers 31a and 31b define a nip therebetween through which documents such as banknotes can pass. The drive wheels 13 and doubles detector rollers 31 are spaced apart by a distance less than the thickness of the banknotes being counted. 0

At least a portion of the doubles detector shaft 32 may be hollow. In the present embodiment, the shaft 32 has a solid bore which is locally hollowed out from the back to accommodate opto-sensor assemblies 36a and 36b. The doubles detector shaft 32 is supported by the framework of the assembly 1 , and carries the two doubles detector rollers 31a and 31b. These are identical in construction and each opposed a respective one of the guide wheels 13. In the embodiment shown in Figure 4, the interior of the shaft 32 is accessed via a removable base 38, which is affixed using screws 39. 5

Each doubles detector roller 31 comprises a roller bearing having an annular outer race 31', an annular inner race 31" and bearings 31" positioned between the inner and outer races. It is preferable that each of these components is made of ceramic, resulting in a wholly ceramic bearing 31. However, it is possible that one or other 10 of the races or the bearings could be made of a different material. The use of a ceramic roller bearing 31 ensures that its rotation does not affect the magnetic field detected by the adjacent magnetic detector 20.

The bearing 31 is mounted co-axially about the shaft 32 on a resilient portion 33,

15 which may be made of rubber. The rubber portion may be annular (as shown in Figure 5) or may surround only a portion of the shaft 32 towards the opposing drive wheels 13, as shown in Figure 4. A pin 35, typically made of plastic, abuts the radial inner surface of the inner race 31 " and extends through the rubber portion 33 and an aperture 45 provided in the shaft 32 so as to protrude into the shaft.

20

A moulded plastics housing 40 is mounted within the shaft 32. This housing 40

— — -may~be-pr-o-videdJn_theJoj.m_ola_singIe moulding extending between both of the rollers 31 a and 31 b, in which case it comprises a central tubular portion 40c integral with end portions 40a and b, each of which have a bore 43a and b communicating

25 with the tubular portion 40c. Alternatively, as shown in Figures 4 and 4a, the plastics housing 40 may be provided in the form of two separate components 40a and 40b making up part of the opto-sensor assemblies 46a and 46b (Figure 4a) and the cental tubular portion 40c may be omitted. Each component 40a and 40b is mounted on plates 37a and 37b on base 38 for ease of removal.

30

In the opto-sensor assemblies 36a and b, a pair of light emitting diodes 42a and 42b are mounted in the inner end of the bores 43a and 43b, and a pair of photo- transistors 41a and 41b are mounted on the outer end of the bores 43a and 43b. For clarity, only portions of the connecting wires from the light emitting diodes and the phototransmitters have been illustrated. In fact, these wires will pass along and out of the shaft 32 to monitoring circuitry. To facilitate assembly, all wires extend from the same end of the shaft 32. Each portion 40a and 40b of the housing also has an aperture 44a and 44b communicating with the bores 43a and 43b and in 5 alignment with the apertures 45a and 45b respectively. The pins 35a and 35b extend through the apertures into the bores 43a and 43b.

In use, banknotes B are fed by the transport system 10 into the nip n formed between the doubles detector rollers 31 and the drive wheels 13 (see Figure 5).0 The banknote B will be fed between the drive wheels 30 and doubles detector rollers 31 due to the continuous rotation of the shaft 31a on which the drive wheels 13 are fixably mounted.

Each LED 42 continuously emits light which impinges on respective5 phototransistors 41 causing each phototransistor to pass collected current at an initial level. Each pin 35 normally partially obscures the light path. When a banknote B is presented to the nip N between the drive wheels 13 and the respective doubles detectors rollers 31 , the banknote B will be taken up and transported to the nip, and each rubber portion 33a and 33b will be compressed0 radially inwardly due to pressure exerted from the outer race 31' via the bearings 31 " and the inner race 31 ". This movement will also be accompanied by a radially

thus further obscure the path of optical rays from the LEDs to the phototransistors, thereby further attenuating light transmitted to the phototransistors. 5

The signals from the phototransistors are monitored and their changes used to detect the passing of one or more banknotes through the nip. The reduction in light intensity can be compared with pre-set thresholds in order to determined whether a single banknote has passed through the nip, or whether, if a double thickness is0 detected, the banknotes are overlapped. The arrangement can also be used to identify occurrences of triple banknotes (three notes overlapped), and half notes as well as folded notes. The apparatus may also be used to detect the size of the notes in direction of transport and given approximate measurement of skew. Further details of appropriate monitoring circuitry and processing are detailed in British patent application number 0612856.5 as well as EP0168202, EP0206675, EP0451882, EP0130825 and EP0130824.

By forming rotating parts of the doubles detector assembly from ceramic, the device can be positioned close to the magnetic detector without affecting its output. This makes it possible to produce a more compact apparatus and does away with the need for magnetic shielding. Whilst in this example, the doubles detector rollers 31 and/or a free-wheeling transport roller 14 have been given as examples of ceramic components, it will be appreciated that the same principals apply to any rotating member in the vicinity of the magnetic detector and any such component may advantageously be made of ceramic instead of or in addition to those ceramic components mentioned above.

In a second embodiment of the invention, the roller assemblies 31 A and 31 B in the sheet sensing apparatus 30 may be made of any non-magnetic material, including plastics or non-magnetic metals. Whilst such components may not have the same level of wear-resistance as ceramic rollers, they may be appropriate for use in some applications, and permit close proximity between the magnetic detector and doubles detector.

Claims

1. A document handling apparatus comprising a document path through the apparatus, a transport assembly for conveying a document along the document path, and a magnetic detector device adjacent at least a portion of the document path for detecting magnetic material in passing documents; wherein the transport assembly comprises at least one rotatable member, the rotatable member comprising ceramic material.

2. A document handling apparatus according to claim 1 wherein the ceramic material is zirconia.

3. A document handling apparatus according to claim 1 or claim 2 wherein the at least one rotatable member is a roller, a wheel or a bearing.

4. A document handling apparatus according to any of the preceding claims wherein the at least one rotatable member is mounted on a shaft within the document handling apparatus.

5. A document handling apparatus according to claim 4 wherein the at least one rotatable member is fixedly mounted to the shaft and the shaft is driven so as to rotate the rotatable member.

6. A document handling apparatus according to claim 4 wherein the at least one rotatable member is rotatably mounted to the shaft and is rotated by the passage of passing documents.

7. A document handling apparatus according to any of the preceding claims wherein the at least one rotatable member forms part of a sheet sensing assembly for detecting the passage of documents through the apparatus.

8. A document handling apparatus comprising a document path through the apparatus, a transport assembly for conveying a document along the document path, and a magnetic detector device adjacent at least a portion of the document path for detecting magnetic material in passing documents; wherein the transport assembly comprises a sheet sensing assembly for detecting the passage of documents through the apparatus having at least one rotatable member, the rotatable member comprising non-magnetic material. .

9. A document handling apparatus according to claim 7 or claim 8 wherein the sheet sensing assembly further comprises a shaft on which the at least one rotatable member is rotatably mounted; a guide surface cooperating with the at least one rotatable member to define a nip therebetween, sensing means for sensing deflection of the at least one rotatabie member relative to the guide surface in response to the passage of one or more sheets through the nip and monitoring means connected to the sensing means for monitoring the sensed deflections of the at least one rotatable member.

10. A document handling apparatus according to claim 9 wherein the guide surface comprises at least one guide roller opposing the at least one rotatable member.

11. A document handling apparatus according to claim 9 or claim 10 wherein the at least one rotatable member is mounted on the shaft by means including a resilient portion, such that deflection of the at least one rotatable member relative to the guide surface causes 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 rotatable member.

12. A document handling apparatus according to claim 11 wherein the sensing means are disposed within the shaft.

13. A document handling apparatus according to claim 12 wherein the means mounting the at least one rotatable member onto the shaft further 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.

14. A document handling apparatus according to claim 13, 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.

15. A document handling apparatus according to claim 14, wherein the generating means comprises one or more light emitting diodes, and the receiving means comprises a phototransistor.

16. A document handling apparatus according to any of claims 9 to 15, 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.

17. A document handling apparatus according to any of claims 9 to 16, wherein the at least one rotatable member 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.

18. A document handling apparatus according to claim 17 when dependent on at least claim 13, wherein the rigid member comprises a pin abutting an inner surface of the inner race and protruding through an aperture in the shaft.

19. A document handling apparatus according to any of claims 7 to 18 wherein the sheet sensing apparatus comprises two rotatable members mounted on a shaft and spaced from each other.

20. A document handling apparatus according to any of claims 7 to 19 wherein the sheet sensing assembly is located within the region in which magnetic fields can be sensed by the magnetic detector device.

21. A document handling apparatus according to any of the preceding claims wherein the magnetic detector device comprises at least one magnetic head disposed adjacent to the document path, the at least one magnetic head being adapted to generate a signal upon detecting magnetic material in a passing document.

5 22. A document handling apparatus according to claim 21 wherein the at least one magnetic head is an inductive magnetic head or a magnetoresistive magnetic head.

23. A document handling apparatus according to claim 21 or claim 22 wherein the at least one magnetic head is an active head and comprises magnetic field

10 generating means for magnetising any magnetic material in a passing document, and magnetic field sensing means for detecting changes in the generated magnetic field caused by magnetic material in a passing document.

24. A document handling apparatus according to claim 21 or claim 22 wherein the 15 at least one magnetic head is a passive head and comprises magnetic field sensing means for detecting a magnetic field resulting from magnetised material in a passing document.

25. A document handling apparatus according to claim 23 wherein the magnetic 20 detector device comprises two magnetic heads, the second being a passive head and comprising magnetic field sensing means for detecting a magnetic field — . — resulting-from-magnetised material in a passing document.

26. A document handling apparatus according to any of claims 21 to 24 wherein 25 the magnetic detector device comprises an array of magnetic heads each of which is connected to a respective processor which processes signals generated by the associated magnetic head, and a processing system connected to the processors.

27. A document handling apparatus according to claim 26 wherein the processing 30 system is adapted to, upon relative movement between a document containing a magnetic material and the array of magnetic heads, detect the arrival of the magnetic material at one of the heads and denote that a primary head, and the head on each side a secondary head; thereafter monitor output signals from the primary and secondary heads to generate a representation of the magnetic material, and compare the magnitude of the signals from the primary and secondary heads such that if the magnitude of the output signal from a secondary head exceeds that from the primary head, the primary and secondary heads are reallocated accordingly.

28. A document handling apparatus according to claim 27 wherein the magnetic material is a thread.

29. A document handling apparatus according to any of the preceding claims adapted to handle documents of value, preferably banknotes.

30. A document handling apparatus according to claim 29 further comprising a controller adapted to determine whether each document of value is authentic, or to identify a characteristic of each document of value, based on the output from the magnetic detector device.