Abstract:
A sensing arrangement ( 12 ) is described. The arrangement comprises: a moveable object ( 80 ) including a plurality of marker portions ( 112 ) disposed in a calibrated configuration, each marker portion ( 112 ) being capable of emitting light in response to stimulation. The arrangement also includes a light source ( 42 ) directed towards the marker portions ( 112 ) and for causing light emission therefrom. An imaging device ( 44 ) is directed towards the marker portions ( 112 ) and includes an array of light-detecting elements for sensing light emitted from the marker portions ( 112 ) to generate image data. A processor ( 52 ), in communication with the imaging device ( 44 ), analyses image data received from the imaging device ( 44 ) to determine the location of the moveable object ( 80 ) based on the calibrated configuration.

Description:
BACKGROUND 
   The present invention relates to a sensing arrangement for detecting the position of a moveable device. In particular, the invention relates to a sensing arrangement incorporated in a media handler to detect the position of a moveable device and thereby determine the number of media items in the media handler. The invention also relates to a self-service terminal, such as an automated teller machine (ATM), incorporating a media handler. 
   Media handlers are well known in Self-Service Terminals (SSTs) such as ticket dispensers, photocopiers, ATMs, and such like. In an ATM, a media handler may be a banknote or cheque depository, a currency recycler, or a currency dispenser. 
   A conventional currency dispenser accommodates a currency cassette removably installed therein. In operation, the currency dispenser removes banknotes from the cassette on a per banknote basis. When the number of banknotes remaining is less than a predetermined number, the cassette should be removed and replenished with banknotes. 
   At present, some replenishment organizations replenish currency cassettes at preset time intervals rather than when the number of banknotes remaining falls below a predetermined level. This is partly because of the lack of a simple, low cost, efficient, and accurate way of determining the approximate number of banknotes remaining in a cassette without an operator visiting the ATM in which the currency dispenser is housed. 
   SUMMARY 
   It is among the objects of an embodiment of the present invention to obviate or mitigate one or more of the above disadvantages, or other disadvantages associated with prior art sensing arrangements and/or media handlers. 
   According to a first aspect of the present invention there is provided a sensing arrangement, the arrangement comprising: a moveable object including a plurality of marker portions disposed in a calibrated configuration, each marker portion being capable of emitting light in response to stimulation; a light source directed towards the marker portions and for causing light emission therefrom; an imaging device directed towards the marker portions and including an array of light-detecting elements for sensing light emitted from the marker portions to generate image data; and a processor, in communication with the imaging device, for analyzing image data received therefrom to determine the location of the moveable object based on the calibrated configuration. 
   In one embodiment, the plurality of marker portions comprises a series of lines spaced apart by a fixed distance. The series may include, for example, five or ten lines, and may serve as a graticule, where the spacing between the lines provides the calibrated configuration. 
   In an alternative embodiment, the marker portions may be different parts of a single marker having a predetermined shape, where the shape of the marker provides the calibrated configuration. For example, the marker may have an annular shape (either circular or non-circular, where non-circular includes multi-sided shapes such as polygons), where the size of the aperture in the annulus provides the calibrated configuration. In such an embodiment, the marker portions are diametrically opposite parts of the annulus. It will now be apparent that it is possible to use many different types of shape to provide the marker portions, including a square, a rectangle, a polygon, a cross, and an irregular shape. The important issue is that the shape that is used has marker portions separated by a known relationship (the calibrated configuration). 
   The light source may cause light emission from the marker portions by stimulating the marker portions, or by providing light that is reflected by the marker portions. As used herein, light emission includes the marker portions generating light in response to stimulation and also the marker portions reflecting light received from the light source. 
   The processor preferably has associated firmware, which may be resident in non-volatile storage such as NVRAM. The associated firmware may include an algorithm enabling the processor to calculate the number of pixels separating (or constituting) the marker portions, and to apply a scaling function, or access a table, to determine the distance between the imaging device and the marker portions that this number of pixels corresponds to. 
   Alternatively, the associated firmware may include an algorithm enabling the processor to determine from how many markers light is detected. 
   In one embodiment, the moveable object is a pusher plate mounted within a currency cassette. In other embodiments, however, the moveable object may be any other moving part in a media handler or other device. 
   In embodiments in which the position of the moveable object is associated with a number of media items, the processor may include an algorithm for determining the number of media items based on the moveable object position. It should be appreciated that this number may, for example, be in the range from zero to several thousand. 
   Preferably, the processor controls operation of the light source. The processor may also control operation of a media handler in which the sensing arrangement is mounted, for example, by controlling movement of a pick arm, rotation of rollers, advancing transport belts, and such like. 
   The moveable object may move from a first position, distal (away from the centre of) the imaging device to a second position, proximal (near the centre of) the imaging device. In embodiments where the moveable object relates to the number of media items stored in the media handler, the first position may correspond to the position in which the media handler is full (or empty), and the second position may correspond to the position in which the media handler is empty (or full). For currency cassette embodiments, the first position typically corresponds to the full position; whereas, for currency deposit embodiments the first position typically corresponds to the empty position. 
   It should be appreciated that the resolution of the imaging device should be sufficient so that different pixels detect the marker portions when the moveable object is in the first position compared with when the moveable object is in the second position. The field of view of the imaging device should also be sufficient to detect the marker portions. 
   Embodiments within this aspect of the present invention use the fact that as a moveable object approaches the imaging device, an increasing number of pixels separate the pixels that sense opposing marker portions. 
   As a result of this aspect of the invention a simple, low cost sensing arrangement is provided that enables the position of a moveable object to be determined without requiring the moveable object to have an electrically powered indicator. 
   A media handler according to this aspect of the invention may co-operate with a self-service terminal that provides status information to a remote networked management centre, thereby allowing a remote replenisher to be updated with information about the media items stored within the media handler. 
   According to a second aspect of the present invention there is provided a media cassette for use in a media handler, the cassette comprising: a moveable object including a plurality of marker portions disposed in a calibrated configuration, each marker portion being capable of emitting light in response to stimulation; a shutter disposed at one end of the cassette and retractable on insertion of the cassette into the media handler to provide an unobstructed light path from the marker portions to an imaging device in the media handler thereby enabling the imaging device to determine the location of the moveable object. 
   Preferably, the moveable object is a pusher plate for urging media items to one end of the cassette. Alternatively, the moveable object may be a part that is moved (for example, raised) by media items as successive media items are inserted into the cassette. 
   Preferably, the shutter is used as an exit port through which media items are dispensed. 
   The cassette may include a lid securely closeable against a body to prevent tampering or unauthorized access to the cassette. Alternatively, the cassette may be an open hopper without a lid. 
   Preferably, the marker portions are disposed on the pusher plate. 
   In one embodiment, the marker portions comprise luminescent material. Luminescence, as used herein, relates to emission of light that persists for a sufficient amount of time to allow detection of that light. Luminescence is used herein in a relatively broad sense and includes phosphorescence. Luminescence may be stimulated by any convenient means, for example, optical, magnetic, chemical, electrical or otherwise. In many embodiments, optical stimulation is preferred as this does not require any electrical connection with the marker portions. 
   In another embodiment, the marker portions comprise reflective material. 
   According to a third aspect of the present invention there is provided a media handler incorporating the sensing arrangement according to the first aspect of the invention. 
   The media handler may be a media dispenser, a currency recycler, a depository, or such like. 
   The media handler may be a module that is removably incorporated into a Self-Service Terminal such as an ATM, a photocopier, or a ticket kiosk. 
   The SST may relay information about how many media items are present to a management centre and/or a replenishment organization. The management centre or replenishment organization may be located remote from the media handler. 
   According to a fourth aspect of the present invention there is provided a method of sensing a moveable object, the method comprising: directing light towards a moveable object including a plurality of marker portions disposed in a calibrated configuration, each marker portion being capable of emitting light in response to stimulation; sensing light emitted from the marker portions; generating image data based on the sensed light; analyzing the image data; and determining the location of the moveable object based on the calibrated configuration. 
   The method may further comprise, estimating a number of media items using the location of the moveable object. This may be achieved by implementing an algorithm that performs a scaling function. Alternatively, this may be achieved by accessing a lookup table. 
   It will be appreciated that this method has applications outside media handlers, for example in complex machinery, industrial plants, vehicles, and many other applications. 
   According to a fifth aspect of the present invention there is provided a sensing arrangement, the arrangement comprising: a moveable object including a plurality of marker portions disposed in a calibrated configuration; an imaging device directed towards the marker portions and including an array of light-detecting elements for sensing light received from the marker portions to generate image data; and a processor, in communication with the imaging device, for analyzing image data received therefrom to determine the location of the moveable object based on the calibrated configuration. 
   The word “media” is used herein in a generic sense to denote one or more items, documents, or such like having a generally laminar sheet form; in particular, the word “media” when used herein does not necessarily relate exclusively to multiple items or documents. Thus, the word “media” may be used to refer to a single item (rather than using the word “medium”) and/or to multiple items. The term “media item” when used herein refers to a single item or to what is assumed to be a single item. The word “object” is used herein in a broader sense than the word “media”, and includes non-laminar items, such as parts of a media handler (for example, a pick arm, a purge pin, and a timing disc). 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other aspects of the present invention will be apparent from the following specific description, given by way of example, with reference to the accompanying drawings, in which: 
       FIG. 1  is a simplified schematic side view of a media handler including a sensing arrangement according to one embodiment of the present invention, with parts of the dispenser simplified and other parts omitted for clarity; 
       FIG. 2  is a block diagram illustrating one part of the media handler of  FIG. 1  (the sensing arrangement) in more detail; 
       FIGS. 3   a  to  3   d  are schematic views of another part of the media handler of  FIG. 1  (the currency cassette) in more detail; 
       FIG. 4  is a schematic diagram showing part of the currency cassette of  FIG. 3  (the pusher plate and marker portions) in more detail; 
       FIG. 5   a  is a graph of intensity versus pixel number for a line of pixels on the sensing arrangement of  FIG. 2 , and the relative size of the marker portions of  FIG. 4 ; 
       FIG. 5   b  is a graph of intensity versus pixel number for the same line of pixels on the sensing arrangement of  FIG. 2  as for  FIG. 5   a , and the relative size of the marker portions of  FIG. 4 ; 
       FIG. 6  is a simplified block diagram illustrating a self-service terminal including the media handler of  FIG. 1 ; and 
       FIGS. 7   a  to  7   d  are schematic diagrams illustrating alternative configurations of the marker portions of  FIG. 4 . 
   

   DETAILED DESCRIPTION 
   Reference is now made to  FIG. 1 , which is a simplified schematic side view of a media handler  10  according to one embodiment of the present invention. The media handler  10  is in the form of a front access currency dispenser, and includes a sensing arrangement  12  (shown as a broken line) according to one embodiment of the present invention. 
   The currency dispenser  10  comprises a pick module  14  mounted beneath a presenter module  15  and releasably coupled thereto. 
   The pick module  14  has a chassis  16  into which a currency cassette  18  is slidably inserted. When in situ, the chassis  16  and cassette  18  co-operate to present an aperture (defined by a frame  20 ) in the cassette  18  through which banknotes  22  are picked. The pick module  14  includes a sensor station  23  and a pick unit  24  for picking individual banknotes  22  from the inserted currency cassette  18 . 
   The currency dispenser  10  also has a transport arrangement  26  (shown as a block arrow for clarity) for transporting picked banknotes  22  from the pick module  14  to a note thickness sensing site  28  within the presenter module  15 . The transport arrangement  26  may be implemented by any convenient mechanism. In this embodiment, a gear train is used as this enables an additional pick module to be coupled to the pick module  14 . Other transport arrangements include stretchable endless belts, skid plates, and the like. 
   At the note thickness sensing site  28  the thickness of the transported banknote  22  is sensed to ensure that only one banknote has been picked. Suitable sensors may include one or more of linear variable differential transducers (LVDTs), optical sensors, strain gauge sensors, Hall effect sensors, capacitive sensors, and such like. In this embodiment an optical sensor is used. 
   At the sensing site  28 , if multiple banknotes  22  have been picked in a single operation (that is, if a faulty pick has occurred), then these multiple banknotes are diverted to a purge bin  30  via a purge transport  31  (shown as a block arrow for clarity). The purge transport  31  is in the form of a pivoting belt that allows the banknotes to fall into the purge bin  30  under the influence of gravity. If only a single banknote  22  has been picked, then this banknote is directed towards a stacking wheel  32  for collating multiple individual banknotes into a bunch of banknotes. The bunch of banknotes is then transported by a bunch note presenter  34  (shown as a block arrow for clarity) from the stacking wheel  32  to an exit port  36  in the form of a shuttered aperture, thereby allowing a customer to remove the bunch of banknotes from the currency dispenser  10  via the exit port  36 . 
   Referring now also to  FIG. 2 , which is a block diagram illustrating the sensing station of  FIG. 1  in more detail, the sensing station  23  comprises a light source  42  in the form of one or more light emitting diodes, and an imaging device  44 , in the form of a semiconductor including an array of light sensitive elements (pixels). One suitable type of imaging device  44  is a CMOS image sensor in the form of a National Semiconductor (trade mark) LM9630 100×128, 580 fps Ultra Sensitive Monochrome CMOS Image Sensor. The light source  42  radiates light (illustrated by arrow  46 ) into the currency cassette  18 , and the CMOS sensor  44  detects light (illustrated by arrow  48 ) emitted from the currency cassette, as will be explained in more detail below. 
   The currency dispenser  10  includes a controller  50  for controlling the operation thereof. The controller  50  comprises: a processor  52  and associated RAM  54  for receiving and temporarily storing the output of the sensor  44 ; non-volatile memory  56 , in the form of NVRAM for storing instructions for use by the processor  52  (the non-volatile memory  56  and instructions are collectively referred to herein as firmware); and a communications facility  58 , in the form of a USB port, for communicating with an external control device (not shown). The external control device may be used for controlling operation of a self-service terminal in which the currency dispenser  10  is mounted. 
   The primary functions of the processor  52  are (i) to control operation of the dispenser  10  by activating and de-activating motors (not shown), and such like; and (ii) to capture and analyze data collected by the image sensor  44 . Function (i) is well known to those of skill in the art, and will not be described in detail herein. Function (ii) is described in more detail below. 
   Reference is now also made to  FIGS. 3   a  to  3   d , which show the currency cassette  18  in more detail.  FIG. 3   a  is a front perspective view of the cassette  18  comprising a body  70  and a lid  72  secured thereto by a latch  73 .  FIG. 3   b  is a rear perspective view of the cassette  18  with the lid  72  removed and inverted.  FIG. 3   c  is a schematic side view of the cassette  18  with one sidewall removed for clarity.  FIG. 3   d  is a rear elevation of the cassette  18 . 
   The cassette  18  has a handle  74  at one end (the handle end  76 ) to allow the cassette  18  to be inserted into and removed from the dispenser  10 , and to be carried between the dispenser  10  and a cash-in-transit vehicle (not shown). The cassette  18  also has a dispensing end  78  opposite the handle end  76  and through which banknotes  22  are removed for dispensing. 
   The cassette  18  comprises: a moveable object  80  in the form of a pusher plate; urging means (not shown) in the form of a spring-biased guide on which the pusher plate  80  is mounted; a door shutter  84  openable on insertion into the pick module  14  to reveal an aperture  86  defined by the frame  20  and through which banknotes  22  stored in the cassette  18  are removed. 
   The cassette further comprises banknote height guides  88  spatially separated from an underside of the lid  72  by spacers  90 , and banknote width guides  92  on which the banknotes  22  rest and which reduce lateral movement of the banknotes  22 . 
   Reference is now also made to  FIG. 4 , which is a schematic diagram showing the pusher plate  80  in more detail. Pusher plate  80  includes an end portion  100  extending beyond banknotes  22  stored in the cassette  18  and visible to the sensing station  23  when the door shutter  84  is open (that is, the end portion  100  is visible through the aperture  86 ). 
   The end portion  100  includes a plurality of marker portions  102   a,b,c,d,e,f  in the form of fluorescent lines printed onto the pusher plate  80  in a calibrated configuration using fluorescent ink. In this embodiment, the calibrated configuration is a series of six lines spaced apart by one millimeter (1 mm). In this embodiment the marker portions  102  are located to one side of the banknotes to ensure that the marker portions  102  are visible to the sensing station  23 . 
   When the currency cassette  18  is inserted into the pick module  14 , the shutter door  84  is opened and the sensing station  23  has line of sight access to the marker portions  102 . When this occurs, the controller  50  activates the LEDs  42  for a predetermined time period (typically of the order of a few tens of milliseconds) then de-activates the LEDs  42 . The light emitted from the LEDs  42  stimulates the fluorescent lines  102  and the lines  102  emit light, which may persist for tens of milliseconds. This emitted light is detected by the CMOS sensor  44  and the resulting pixel data is conveyed to the controller  50  for processing. 
   At the controller  50 , the processor  52  executes firmware that analyses the pixel data acquired to determine how many pixels separate the lines  102 . 
   There are a number of different techniques that may be used to analyze data recorded by the pixels. This analysis may be for the purpose of determining the position of a moving object and/or to measure properties of an object and/or relations between objects. 
   In this example, single threshold analysis is used. This involves determining how many pixels in a physical area of the array receive light that exceeds a predetermined threshold. The threshold is set so that only those pixels that detect light from the marker portions  102  exceed the threshold. 
   Reference is now made to  FIG. 5   a , which is a graph of pixel intensity versus pixel number for a line of pixels on the CMOS sensor  44 , and the relative size of the marker portions  112  as viewed by the CMOS sensor  44 . 
     FIG. 5   a  relates to a measurement taken when the cassette  18  was full of banknotes  22  and the pusher plate  80  was furthest from the sensing station  23 . In  FIG. 5   a , the predetermined threshold is illustrated by line  110 . The processor  52  acquires data corresponding to the measured intensity detected by each pixel. The processor  52  then identifies those pixels that exceed the predetermined threshold to locate marker portion detection zones (illustrated by circles labeled  112   a  to  112   f ) on the array of pixels. The processor  52  then determines the spacing between adjacent marker portion detection zones, for example, between zone  112   a  and  112   b . The processor  52  may determine the number of pixels between the marker zones  112 . This may be achieved by determining the number of pixels between average centers of the marker zones  112  (illustrated by arrow  114 ), or the number of pixels between adjacent edges of the marker zones  112  (illustrated by arrow  116 ), or the number of pixels between any two other convenient reference points. 
   Once the processor  52  has determined the number of pixels between adjacent marker zones  112 , the processor executes a scaling algorithm  118  resident in RAM  54  to convert the number of pixels to a number of banknotes  22 . 
   In this example ( FIG. 5   a ), adjacent marker zones  112  are separated by five pixels, which translates to the pusher plate  80  being approximately twenty-five centimeters from the sensing station  23  (which is the separation of the pusher plate  80  from the sensing station  23  when the cassette  18  is full of banknotes). This may correspond to the currency cassette  18  having approximately a thousand banknotes therein. The actual number of banknotes stored depends on the thickness and condition of the currency used. 
   Reference is now made to  FIG. 5   b , which is a graph of intensity versus pixel number for the same line of pixels on the CMOS sensor  44  as for  FIG. 5   a , and the relative size of the marker portions  102  as viewed by the CMOS sensor  44 .  FIG. 5   b  relates to a measurement taken when the cassette  18  was nearly empty and the pusher plate  80  was closer to the sensing station  23 . In  FIG. 5   b , the same predetermined threshold is used as for  FIG. 5   a.    
   The processor  52  analyses the measured intensity detected by each pixel in the same way as for the example of  FIG. 5   a , then identifies those pixels that exceed the predetermined threshold to locate marker portion detection zones (illustrated by circles labeled  112   a  to  112   f ) on the array of pixels. The processor  52  then determines the number of pixels between the marker zones  112 . Once the number of pixels between adjacent zones has been determined, the processor  52  uses the scaling algorithm  118  to determine the position of the pusher plate  80 . 
   In this example, adjacent marker zones  112  are separated by twelve pixels, which translates to the pusher plate  80  being approximately five centimeters from the sensing station  23 . This may correspond to the currency cassette  18  having approximately fifty banknotes therein. 
   Reference is now made to  FIG. 6 , which is a simplified block diagram illustrating an ATM  200  including the dispenser  10 . 
   The ATM  200  includes a PC core  202 , which controls the operation of peripherals within the ATM  200 , such as the dispenser  10 , a display  204 , a card reader  206 , an encrypting keypad  208 , and such like. The PC core  202  includes a USB port  210  for communicating with the USB port  58  in the dispenser  10 . 
   During operation, the PC core  202  periodically polls the dispenser  10 , and/or the dispenser  10  notifies the PC core  202  of the number of banknotes remaining in each currency cassette  18  stored therein. In this embodiment, only one currency cassette  18  is used, but in other embodiments, multiple media cassettes may be used. 
   The PC core  202  includes an Ethernet card  212  for communicating across a network to a remote server  220 . The server  220  has an Ethernet card  222  and is located within a management centre  230 . The server  220  receives information about the amount of currency remaining in the dispensers (such as dispenser  10 ) from ATMs (such as ATM  200 ). This information is collated and used to schedule replenishment operations. 
   The management centre  230  includes a plurality of terminals  232  interconnected to the server  220  for monitoring the operation of a large number of such ATMs. The server  220  includes a wireless communication card  234  for communicating with wireless portable devices  240 . These devices  240  are similar to portable digital assistants (PDAs). 
   In this embodiment, the server  220  is a Web server allowing password protected access to authorized personnel, such as field engineers and replenishment personnel issued with the portable devices  240 , and human agents operating the terminals  232 . The portable devices  240  may be installed in cash-in-transit vehicles to allow replenishment personnel to determine if any ATMs  200  require replenishment in advance of any scheduled replenishment operation. 
   Reference is now made to  FIGS. 7   a  to  7   d , which illustrate different configurations of marker portions. In  FIG. 7   a , concentric circles are used as marker portions  132   a,b,c . In  FIG. 7   b , a series of lines serve as marker portions  142   a  to  142   d , and the lines have a perpendicular centre line  144  for aiding alignment. In  FIG. 7   c , a single circle is shown that has marker portions  152   a,b  diametrically opposite each other. In  FIG. 7   d , a single biconvex shape is shown that has marker portions  162   a,b  diametrically opposite each other. 
   It will now be appreciated that the above embodiment has the advantage that accurate information about the number of banknotes remaining within a currency cassette can be obtained by the dispenser  10  and relayed to a remote management centre to assist with scheduling currency replenishment operations. 
   Various modifications may be made to the above embodiments within the scope of the present invention. For example, in other embodiments, multiple pick modules may be included in each dispenser. In embodiments, where multiple pick modules are used, there may be an optical station for each pick module, or a single optical station having multiple optical paths, one optical path for each pick module. 
   In the above embodiment, the media items were currency items; whereas, in other embodiments financial documents, such as cheques, Giros, invoices, and such like may be handled. 
   In other embodiments, media items other than currency or financial documents may be dispensed, for example a booklet of stamps, a telephone card, a magnetic stripe card, an integrated circuit or hybrid card, or such like. 
   In other embodiments, a dispenser may have one or more cassettes containing currency, and one or more cassettes storing another type of media item capable of being removed by a pick unit. 
   In other embodiments, the imaging device may be located on a control board, in the pick module, or in some other convenient location. In other embodiments, the media handler may be a currency recycler, a ticket dispenser or depository, or such like. 
   In other embodiments, the light source may be in the form of any convenient illumination source, such as a very low power laser, a tungsten filament, or such like. 
   In other embodiments, the marker portions may comprise reflective material so that light incident from the light source is reflected by the reflective material. 
   In other embodiments, the calibrated configuration may be in the form of a circle, an ellipse, a square, a rectangle, a polygon, or such like. In other embodiments, the calibrated configuration may be in the form of a series of shapes, where each shape has the same outline but a different size (such as the concentric circles of  FIG. 7   a ), or some or all of the shapes may have a different outline. 
   The transports described above comprise a combination of rollers and endless belts. The transports may also include one or more skid plates. These transports are all well known in the art, and different transports, such as gear trains, may be used with other embodiments of the present invention. 
   In other embodiments, other known types of image processing may be used to analyze images captured by the image sensor. 
   In other embodiments the scaling algorithm may be replaced by a table or some other mechanism for converting a number of pixels to a position or a number of banknotes. 
   In other embodiments, the processor may first convert a number of pixels into a position, then convert (using an algorithm, a table, or some other mechanism) the position to a number of banknotes or other media items. This has the advantage that different media items may be used in one media handler, but the same scaling algorithm or table may be used initially to determine the position of the moveable object, then another mechanism, specific to the media being estimated, may be used to estimate the number of media items therein.