WO2010018414A1

WO2010018414A1 - Improvements relating to bands

Info

Publication number: WO2010018414A1
Application number: PCT/GB2009/051027
Authority: WO
Inventors: Tim Clarke
Original assignee: Duff Design Limited
Priority date: 2008-08-14
Filing date: 2009-08-14
Publication date: 2010-02-18
Also published as: GB0814896D0

Abstract

Methods and systems are disclosed for detecting and/or verifying the position of a join in an band for a band-drive article. One method comprises providing a band comprising first and second web portions, each having a marker and being joined at a join, the markers of the web portions defining a discontinuity, such as a contrast, about the join. The discontinuity is detected with a detector and an actual position of the join determined, based on the detected discontinuity. The actual position of the join may then be verified against a reference position or a reference range. A marked band for a band-drive article having a join and facilitating detection of the join by a detector is also disclosed.

Description

IMPROVEMENTS RELATING TO BANDS

This invention relates to the detection and/or verification of joins in bands for band-drive articles. More particularly, though not exclusively, this invention relates to a quality control method for detecting and/or verifying the position of a join in a band during the manufacture of a band-drive article.

Band-drive articles of the type referred to are exemplified by our European patent EP1 140639, in the form of band-drive packages. The packages of EP1 140639 are characterised by a band (or belt) that extends around a supporting structure, such as a planar divider, to slide around that structure in use. The divider is typically supported within a sleeve defining the overall size and shape of the package; the divider and the sleeve may be integral panels of a common folded blank. Tab members are attached to the band, one each side of the divider, such that moving one tab member out of the package slides the band around the divider. That movement of the band, in turn, drives the other tab member to move out of the package in an opposite direction. Conversely, movement of one tab member back into the package also, via the band, drives the other tab member back into the package. The band therefore acts to drive and couple the tab members for opposing movement into and out of the package.

One or both of the tab members of the packages of EP1 140639 can be trays or other structures such as blister packs adapted to support, and optionally to display, the contents of the packages. Alternatively, band-drive articles may comprise one or more tab members that simply display information such as branding or instructions for use of the contents of the package.

Trays and information-carrying tab members may be combined in a single band-drive article. Thus, for example, one tab member can support an instruction leaflet, which may fold out when that tab member is pulled out of the package to drive movement of another tray-type tab member carrying one or more items. This type of band-drive package is particularly suitable for pharmaceuticals and their associated instruction pamphlet.

A range of challenges presents itself during automated production of band-drive articles, especially at high speed. One particular challenge relates to placing the band onto a divider of a blank or other supporting structure, while maintaining the close sliding fit that is essential to smooth running of the band when the package is in use. Our international patent application published as WO 2007/129090, which is incorporated herein by reference, describes a method and apparatus for making a band-driven package or a component thereof, which addresses this challenge.

To facilitate the description of the prior art process of WO 2007/129090, reference will now be made to Figures 1 and 2 of the accompanying drawings in which:

Figure 1 is a flow diagram of the major steps involved in the prior art process of making a band-drive package; and

Figure 2 is a schematic plan view of a linear package-making machine operating in accordance with the prior art process of Figure 1 , in the context of the processing undergone by successive blanks through the machine.

With reference to Figures 1 and 2, a machine 100 takes blanks 102 each having an integrated divider 104 and then introduces strips of web 106, one each side of a divider to sandwich the divider between the strips 106. The strips 106 are then joined together and cut to create a band 108 around the divider 104, the band 108 including a first join 1 10 immediately ahead of the divider 104, i.e. downstream, and a second join 1 12 immediately behind the divider 104, i.e. upstream.

Once the second join 1 12 and cut have been made to complete the band 108, the band 108 is advanced around the divider 104 to reposition the joins 110, 112 inboard of leading and trailing edges 1 14, 116 of the divider 104. The repositioning, which may be clockwise or counter-clockwise as suitable, prevents the joins 110, 1 12 snagging on the leading and trailing edges 114, 1 16 of the divider 104 when a resulting package 118 is used.

A first tab member 120, such as a blister pack, is applied adhesively to the first join 110 of the band 108 whereupon the blank 102 is folded around the first tab member 120 to invert the band 108. This presents the second join 1 12 of the band 108, whereupon a second tab member 122 is applied adhesively to that join 1 12. Applying adhesive over the joins 110, 112 in this way helps to reinforce them. When the second tab member 122 has been put in position, final folds are made as to complete the package 118, in which the blank 102 defines a sleeve around the tab members 120, 122 and also defines the divider 104 that supports the band 108 for driving relative opposed movement of the tab members 120, 122 in use.

Each of the steps described above must be completed successfully to ensure that the finished package is of an acceptable quality. The step of repositioning the joins once the band has been formed around the divider is particularly important to the quality of the resulting package. If the position is incorrect, snagging of the join(s) at leading and trailing edges of the divider could otherwise interrupt the smooth running of the band around the divider, ruining the perception of quality and introducing a risk of breakage. It is even possible that adhesive will be applied beside a join rather than over it: this will fail to reinforce the join.

Currently, if a problem with this particular manufacturing step occurs, i.e. if the join is repositioned incorrectly, or not at all, this may only be identified downstream of the repositioning step in the production line. Indeed incorrect positioning may not be recognised until the package is completed, or some time thereafter as not every product is quality tested. By this stage, if the position of the join is found to be incorrect, a significant amount of material and energy may have been wasted by producing further defective packages in continuing inaccurate production.

The invention has been conceived by the Applicant to provide solutions to the problems described above.

In a first aspect, the invention resides in a method of determining the position of a join in a band for a band-drive article, the method comprising: providing a band comprising first and second web portions each having a marker and being joined at a join, the markers of the web portions defining a discontinuity about the join; detecting the discontinuity with a detector; and determining an actual position of the join based on the detected discontinuity.

Such a method has application during the making of band-drive packages, for example in the automated process described previously. By determining the actual position of the join it is possible to check, for example, whether any repositioning of the join has been undertaken successfully. The invention enables the position of the join to be determined immediately after a repositioning step, meaning that it is not necessary to await the completion of band-drive articles before performing a quality check relating to the positions of the joins in their bands. This in turn enables a swift response to faults or to incorrect calibration in production line environments, for example by temporarily halting production, which can prevent waste of materials, time and energy.

Preferably, the discontinuity may comprise a contrast. The contrast may be detected in the electromagnetic spectrum, for example in the visual spectrum or the ultraviolet spectrum. A contrast apparent only in the ultraviolet spectrum typically has the advantage of being invisible to the human eye, which may advantageously improve the visual appeal of band-drive articles.

Advantageously, the discontinuity may be defined between the markers and unmarked portions of the first and second web portions. For example, the markers may be black and the unmarked portions may be of a light colour, white or translucent.

The discontinuity may conveniently result from a misalignment of the markers of the first and second web portions.

The markers of the first and second web portions may advantageously abut the join to assist particularly precise detection of the position of the join.

Conveniently, the markers of the first and second web portions may be substantially identical. This can help to keep manufacturing costs low since the first and second web portions may then also be of identical material.

To facilitate the definition of the discontinuity, the markers of the first and second web portions may preferably be offset to a lateral side of their associated web portion. In a particularly preferred arrangement, the markers of the first and second web portions may advantageously be offset to opposed lateral sides to define the discontinuity.

The first and second web portions may preferably be opposed in orientation to enable the markers to define the discontinuity. This is particularly advantageous as it may enable the same web material to be used for both web portions, if the markers are laterally offset as described above.

Advantageously, the markers may comprise one or more stripes. Preferably, each of the web portions may comprise first and second parallel stripes.

For effective utilisation of printing space, the markers may preferably take up less than 20% of a total printing area of their associated web portion. The total printing area may, for example, be defined as one side of the web portion. Thus, where the markers comprise two stripes extending in parallel along the web, the widths of the two stripes may conveniently add up to less than 20% of the width of the web.

The first and second web portions may conveniently be joined at first and second joins and the markers may define a contrast about each join. For ease of manufacture, the markers may then advantageously extend between the first and second joins.

Preferably, the detector, which may comprise a camera, may capture an image of the discontinuity. Determining the actual position of the join based on the detected discontinuity may then advantageously comprise: processing said image using contrast recognition software to determine a discontinuity position; and calculating an actual position of the join based on said discontinuity position and a further, fixed comparison (or datum) position in said image. The comparison position may conveniently be a leading or trailing edge of a divider supporting the band.

The method may advantageously further comprise verifying the position of the join by comparing the actual position of the join against a reference position or a reference range. The actual position and the reference position or reference range may be compared by a processing unit such as a computer.

Where the position of the join is verified, the method may preferably further comprise rejecting the band if the actual position of the join fails to match the reference position or fails to fall within the reference range. Rejecting the band may comprise removing the band and any associated blank or article from a production line, for example, conveniently, by releasing it from a conveying means and allowing it to fall into a reject area. Advantageously, the method may also comprise initiating a recalibration sequence via a control module of a band production line if a band is rejected or if the position of the join drifts from a desired position or range of positions. A band-forming station and/or a band- repositioning station of the production line may thus be recalibrated if the band is rejected. Additionally or alternatively, the method may further comprise stopping a band production line if the band is rejected.

The band may be provided in-line, for example at a band-forming station by joining the first and second web portions at one or more joins to form a band.

To assist in improving the quality of band-drive articles, the method may further comprise repositioning the join at a join-repositioning station prior to detecting the discontinuity.

In a second aspect, the invention resides in a system for determining the position of a join in a band for a band-drive article, the system comprising: a band source, arranged to provide a band comprising first and second web portions each having a marker and being joined at a join, the markers of the web portions defining a discontinuity about the join; a detector for detecting the discontinuity; and a processing unit for determining an actual position of the join based on the detected discontinuity.

The advantages and preferred features of the method of the first aspect of the invention apply mutatis mutandis to the system of the second aspect of the invention.

The band source of the system may preferably comprise a band-forming station having first and second marked web feeds and a welding and cutting head for joining and cutting the first and second web feeds at the join to form the band. The detector of the system may advantageously comprise a camera.

The discontinuity may define a contrast and the processing unit may preferably comprise contrast recognition software.

To aid in improving the quality of band-drive articles, the system may advantageously comprise a join-repositioning station for repositioning the join of the band.

Preferably, the processing unit may be programmed to verify the actual position of the join against a reference position or a reference range. The system may then advantageously comprise a reject station for rejecting the band if the actual position of the join fails verification by the processing unit.

The system may preferably comprise a control module for operatively linking at least the band source and the processing unit. Advantageously, the control module may operatively link at least the following, if present in the system: band source (e.g. band- forming station); join-repositioning station; processing unit (e.g. as part of a join- verification station); reject station; and downstream processing sections.

Conveniently, the processing unit may be integral with the control unit.

The invention also extends to a production line comprising any system or operating in accordance with any method described herein for determining the position of a join in a band for a band-drive article.

From a third aspect, the invention resides in a band for a band-drive article, the band comprising first and second web portions each having a marker, wherein the first and second web portions are joined at a join and the markers of the web portions define a discontinuity about the join to facilitate detection of the join by a detector.

The advantages and preferred features of the method of the first aspect of the invention apply mutatis mutandis to the band of the third aspect of the invention.

Reference has already been made to Figures 1 and 2 of the drawings to describe the prior art. In order that the invention may be readily understood, reference will now be made, by way of example, to the remaining drawings in which:

Figure 3 is a schematic view of a production line for band-drive packages incorporating exemplary embodiments of the invention;

Figure 4(a) is a perspective view of upper and lower marked web feeds of a band-forming station of the production line of Figure 3;

Figure 4(b) is a schematic side view of the band-forming station; Figures 5(a) and 5(b) are sequential schematic side views showing a first technique for repositioning a join in a band, which may be employed in a join- repositioning station of the production line of Figure 3;

Figures 6(a) and 6(b) are sequential schematic side views showing a second, alternative join-repositioning technique which may be employed in the join- repositioning station;

Figure 7(a) is a plan view of a band in a join-verification station of the production line of Figure 3, following join-repositioning by one of the techniques of Figures

5(a) to 6(b);

Figure 7(b) is a schematic side view of the join-verification station showing detection of the band by a camera;

Figure 8 is a flow diagram summarising the combined working of the join- verification station, a control module and a reject station of the production line of Figure 3 to provide a system and method of quality control;

Figure 9 is a schematic side view of a reject station of the production line of

Figure 3 showing the rejection of a band; and

Figure 10 is a top view of an alternative marked strip according to the invention.

For completeness, and with reference to Figures 3 to 9, this specification will describe exemplary embodiments of the invention as part of an automated production line 2 for band-drive articles based on the process and machine of WO 2007/129090.

In this context, the specification will discuss the steps of: forming a band having a detectable discontinuity about first and second joins; repositioning the joins; detecting the discontinuity; determining an actual position of the join based on the detection of the discontinuity; verifying the position of the join by comparing the actual position against a reference position; accepting or rejecting the band based on the verification; and performing any requisite recalibrations or production line stoppages. However, it is emphasised that the invention does not necessarily require all of these steps to be performed, either in the order shown or indeed, in some cases, at all. Nor does the invention exclude the possibility of introducing further steps or stages into the production line. The verification of the position of a join in a band for a band-drive article in accordance with the invention may be carried out in a variety of environments, in-line or offline, and the production line described herein is hence merely one preferred example. Thus, feature combinations that do not depart from the scope of the invention as defined by the appended claims, even if not specifically mentioned, should be regarded as disclosed by the following description.

Referring now specifically to the overview of Figure 3, the production line 2 processes cardboard blanks (not shown) of the type used in the process of WO 2007/129090 into band-drive articles in the form of packages (not shown). The production line comprises a band-forming station 4, a join-repositioning station 6, a join-verification station 8, a reject station 10, and downstream processing stations 12. The stations 4, 6, 8, 10, 12 are all operatively linked and controlled by a suitable control module 14, which comprises operator controls (not shown).

The cardboard blanks are carried through the production line 2 by a primary conveyor 16 that links all the stations 4, 6, 8, 10, 12. The primary conveyor 16 may have several separate sections, as convenient.

With reference to Figures 4(a) and 4(b), the band-forming station 4 receives cardboard blanks 18 and encircles an integral divider 20 thereof with a band 22 having first and second joins 24, 26, in the manner of the process and machine of WO 2007/129090. However, in accordance with the present invention, the band-forming station 4 processes upper and lower web feeds 28, 30 comprising markers which create a detectable discontinuity as will now be described.

Figure 4(a) shows a section of the upper and lower web feeds 28, 30, which are simultaneously wound out from opposing rollers 32, 34 of the band-forming station 4, as shown in Figure 4(b). The upper and lower web feeds 28, 30 comprise respective strips of white or translucent flexible plastics web 36, 38, suitably polypropylene film as sold under the trade mark Treofan GND. Each of these upper and lower strips of web 36, 38 is marked with two black stripes 40, 42 which extend in parallel, along the length of the strips 36, 38, offset to one lateral side thereof. The stripes 40 of the upper strip 36 are on a top-side of the upper strip 36, whilst the stripes 42 of the lower strip 38 are on an under-side of the lower strip 38. The stripes 40 of the upper strip 36 are offset to an opposed lateral side of their strip 36 with respect to the stripes 42 of the lower strip 36. Thus the upper strip 36 and the lower strip 38 are identical, save for their orientation: the same web material, suitably orientated, may therefore be used for both strips 36, 38.

To visualise better the orientation of the strips 36, 38 and the asymmetry of the stripes 40, 42 with respect to the strips 36, 38, the stripes 42 of the lower strip 38 have been shown with dotted lines in Figure 4(a). They would normally not be seen from this angle, unless the strips 36, 38 are translucent.

Referring again to Figure 4(b), the two marked strips 36, 38 are processed by the band- forming station 4 to form a band 22 around the divider 20 of a blank 18. This involves simultaneously feeding the strips 36, 38 and the blank 18, in substantially parallel planes, to a heated, reciprocating welding and cutting head 44. The head 44 initially bears down upon the upper strip 36 closely downstream of a leading edge 46 of the divider 20 of the blank 18, pressing the upper strip 36 into contact with the lower strip 38. This joins the upper and lower strips 36, 38 at a first, downstream join 24 and cuts through the joined- together strips 36, 38. Thereafter, as illustrated in the view of Figure 4(b), once the divider 20 has been transported downstream of the head 44 by the primary conveyor 16, the head 44 bears down upon the upper strip 36 closely upstream of a trailing edge 48 of the divider 20, once again pressing the upper strip 36 into contact with the lower strip 38 to join and cut through the strips 36, 38 at a second, upstream join 26. Joining and cutting the strips 36, 38 in this manner completes the band 22 around the divider 20.

To prevent snagging of the band 22 once the blank 18 has been processed into a package, the outwardly-protruding first and second joins 24, 26 of the band 22 are repositioned at the join-repositioning station 6 by advancing the band 22 around the divider 20, as will now be described.

The blank 18, and the band 22 supported thereon, are transported from the band-forming station 4 to the join-repositioning station 6 by the primary conveyor 16. Several techniques for repositioning the joins 24, 26 of the band 22 are known, for example from WO 2007/129090, and these may all be used in the join-repositioning station 6, alone or in combination.

By way of example, Figures 5(a) and 5(b) illustrate a first technique in which a secondary conveyor 50 grips the band 22 as the blank 18 is moved through the join-repositioning station 6 by the primary conveyor 16 (not shown in Figures 5(a) and 5(b)). The primary conveyor 16 moves slightly faster than the secondary conveyor 50 and, as a result of this differential in movement speeds, the band 22 is turned relative to the blank 18, counterclockwise in the view of Figure 5(b), to reposition the first and second joins 24, 26 inboard of the leading and trailing edges 46, 48 of the divider 20 of the blank 18. Figures 6(a) and 6(b) illustrate a second technique for repositioning the joins 24, 26 of the band 22, in which counter-rotating rollers 52, 54 engage the band 22 above and below the blank 18 and index the angular position of the band 22 to the necessary extent.

Following repositioning of the joins 22, 24, the primary conveyor 16 carries the blank 18, and the band 22 supported thereon, from the join-repositioning station 6 to the join- verification station 8.

Figure 7(a) shows a plan view of the band 22 as it passes through the join-verification station 8, and in particular the first, downstream join 24, which has been repositioned to lie inboard of the leading edge 46 of the divider 20 of the blank 18, on an upper side thereof. Notably, the stripes 40 of the upper strip 36 misalign with the stripes 42 of the lower strip 38, by virtue of their opposed asymmetry, which results from the opposed orientation of the strips 36, 38.

The misalignment of the stripes 40, 42 of the upper and lower strips 36, 38 creates a distinct boundary 56 at their meeting point on the band, along the join 24. This discontinuity or contrast created at the join 24 by virtue of interference between the stripes 40, 42, is readily recognisable by machine vision used to detect and verify the position of the second join 24 in the join-verifying station 8.

With reference to Figure 7(b), the join-verification station 8 comprises a detector in the form of a camera 58, which is suitably positioned and configured to capture images of the band 22 as it moves through the join-verification station 8 supported by the blank (not shown in Figure 7(b) for clarity), on the primary conveyor 16. A processing unit 60 of the joint-verification station processes the images captured by the camera 58. The processing unit 60 is linked to the control module 14 of the production line 2.

Details of the working of the join-verification station 8 will now be described with reference to the flowchart of Figure 8.

Initially, at stage 200, the camera 58 captures images of the band 22. The camera 58 is configured to capture the discontinuity or contrast between the markers of the upper and lower strips 36, 38 and remaining unmarked portions 62 of the strips 36, 38. As the markers of the strips in this production line 2 are black stripes 40, 42, which contrast visually from the white or translucent remaining unmarked portions 62, the camera 58 captures images based on the visual spectrum of electromagnetic radiation. However, if, alternatively, ultraviolet markers were used, as is within the scope of this invention, the camera 58 would suitably capture images in the ultraviolet spectrum. Ultraviolet markers, whilst more expensive, have the advantage of being invisible to the human eye and can therefore improve the visual appeal of resultant band-drive articles, particularly when used in combination with translucent strips. Depending on the precise nature of the markers, the camera 58 could also be configured to detect a direct contrast, for example in colour, between the markers of the upper and lower strips 36, 38.

The camera 58 converts the captured images into a digital output signal, which is picked up by the processing unit 60. The processing unit 60 is programmed with image- processing software comprising a pattern recognition engine in order to identify the chosen discontinuity or contrast in the image received via the digital output signal of the camera 58. In this production line 2, at stage 202 in Figure 8, the image-processing software of the processing unit 60 identifies both the distinct boundary 56 created at the first join 24 by the misalignment of the stripes 40, 42 of the upper and lower strips 36, 38, and the leading edge 46 of the divider 20 of the blank 18. Once the boundary 56, i.e. the first join 24, and the leading edge 46 of the divider 20 have been identified, the processing unit 60 calculates their respective positions, and, in particular, their relative distance to determine an actual position of the join. The leading edge 46 acts as a fixed comparison position.

At stage 204 in Figure 8, the processing unit 60 compares the distance between the first join 24 and the leading edge 46 of the divider 20 with a reference value, or a reference value range, that is pre-set, for example by a user, via the control module 14. Thus, the actual position of the first join 24 is effectively compared to a reference position or a reference range.

Depending on the outcome of this comparison, the processing unit 60 decides, at stage 206 in Figure 8, based on programmed criteria, whether or not the position of the first join

24 relative to the leading edge 46 of the divider is acceptable, thus providing verification of the position of the first join 24. Given that the distance between the joins is substantially the same as the length of the divider 20, verification of the position of the first join 24 also verifies the position of the second join 26. However, if desired, a further join-verifying station (not shown) can be employed to check the position of the second join 26 directly.

The decision of the processing unit 60 is communicated to the control module 14, which then takes appropriate further steps. It will be appreciated that the functions of the processing unit 60, namely analysing the images detected by the camera 58, determining the actual position of the first join 24, comparing the actual position of the first join 24 to a reference position or reference range, and deciding whether or not the position of the first join 24 is acceptable, could also be carried out centrally, for example within the control unit 14. Thus the processing unit 60 may be integral with the control unit 14.

The further steps taken by the control module 14 are summarised by stages 206 and 208 in Figure 8. If the position of the first join 24 is acceptable, the band 22 and its supporting blank 18 pass the reject station 10 and proceed into the downstream processing stations 12 of the production line 2 to complete the production of a package in conventional fashion. The downstream processing stations 12 of the production line 2 are identical to those described in WO 2007/129090, and involve the gluing of first and second tab members (not shown), and folding of the blank to form a completed package.

If on the other hand the position of the first join 24 is not acceptable, the control module 14 responds by rejecting the band 22 and blank 18 at the reject station 10. Additionally, the control module 14 may stop the production line 2 to prevent further processing of blanks. This has the dual purpose of enabling a detailed fault analysis and preventing the waste of materials through continuing production of packages having bands whose joins are in an unacceptable position. Alternatively, as downtime of a production line is generally undesirable, the control module 14 may recalibrate the band-forming and/or join-repositioning stations 4, 6 without stopping production. For example, a trend to mis- positon the first join 24 may be corrected simply by changing the relative speeds of the primary conveyor 16 with respect to the secondary conveyor 50 (in the technique of Figures 5(a) and 5(b)) or the speed of the counter-rotating rollers 52, 54 (in the technique of Figures 6(a) and 6(b)).

The reject station 10 may take any suitable form. In this production line 2, with reference to Figure 9, the reject station 10 comprises a gap 64 in the primary conveyor 16 that is bridged by an inverted vacuum conveyor 66. The inverted vacuum conveyor 66 is controlled by the control module 14 (not shown in Figure 9) and grips blanks with the help of suction. The band 22 and supporting blank 18 (not shown in Figure 9) are transferred from an upstream section 68 of the primary conveyor 16 to the inverted vacuum conveyor 66, which, provided that the first join 24 is in an acceptable position, carries the blank 18 and band 22 over the gap 64 to a downstream section 70 of the primary conveyor 16 for further processing into a package, as described above. However, in the event that the processing unit 60 of the join-verification station 8 decides that the position of the first join 24 of the band 22 is unacceptable, the control module 14 temporarily disables, or indeed reverses, the suction of the inverted vacuum conveyor 66 to drop the band 22 and blank 18, under the influence of gravity, through the gap 64 and into a reject area such as a bin 72, as illustrated in Figure 9. Thus the reject station 10 can remove selected blanks and bands from the production line 2, based on the commands of the control station 14.

In summary, the join-verification station 8, the reject station 10 and the control module 14 combine to ensure that band-drive packages produced in the production line 2 meet a desired standard with respect to the positioning of the joins of their band. These components thus offer a method and system of quality control.

While only a selected embodiment has been chosen to illustrate the present invention, it will be apparent to those skilled in the art from that various changes and modifications can be made herein without departing from the scope of the invention as defined in the appended claims.

By way of illustration, a further non-limiting example of an alternative marked strip 300 that could be used as both the upper and lower web feeds 28, 30 (by reversing, as described hereinabove) is shown in Figure 10. The alternative marked strip 300 is comprised of white or translucent flexible plastics web, suitably polypropylene film as sold under the trade mark Treofan GND, and is marked with two stripes 302, 304 which extend in parallel, along the length of the strip, marginally offset to one lateral side thereof. The stripes 302, 304 of the alternative strip 300 are relatively narrow, measuring less than 4 mm in width, and are asymmetrically offset to only a small degree, but nevertheless function to provide a discontinuity or contrast in accordance with the invention.

The narrowness of the stripes leaves more space 306 on the strip for other markings, which need not necessarily contribute to creating a discontinuity in accordance with the invention, but could instead display information such as a legend. In percentage terms, the two stripes, each having a width of less than 4 mm, e.g. 2.5 mm, take up less than 20% of the surface area of the strip, which is 40 mm in width.

The markers of the strips may take any suitable form and need not necessarily be stripes, or abut the join. For instance, the markers could be non-identical and span the entirety of their associated strip to contrast with each other, for example in colour. Also, a variety of detectors, not limited to cameras, may be used, provided that they are suitable for detecting a discontinuity defined by markers of first and second strips of a band.

As aforesaid, the invention is not limited in its application and may be employed wherever there is a need to detect a join of a band for a band-drive article.

Claims

1. A method of determining the position of a join in a band for a band-drive article, the method comprising:

providing a band comprising first and second web portions each having a marker and being joined at a join, the markers of the web portions defining a discontinuity about the join;

detecting the discontinuity with a detector; and

determining an actual position of the join based on the detected discontinuity.

2. The method of Claim 1 , wherein the discontinuity defines a contrast detectable in the electromagnetic spectrum.

3. The method of Claim 2, wherein the contrast is detectable in the visual spectrum.

4. The method of Claim 2 or Claim 3, wherein the contrast is detectable in the ultraviolet spectrum.

5. The method of any preceding claim, wherein the discontinuity is defined between the markers and unmarked portions of the first and second web portions.

6. The method of any preceding claim, wherein the discontinuity results from a misalignment of the markers of the first and second web portions.

7. The method of any preceding claim, wherein the markers of the first and second web portions abut the join.

8. The method of any preceding claim, wherein the markers of the first and second web portions are substantially identical.

9. The method of any preceding claim, wherein the markers of the first and second web portions are offset to a lateral side of their associated web portion.

10. The method of Claim 9, wherein the markers of the first and second web portions are offset to opposed lateral sides to define the discontinuity.

1 1. The method of any preceding claim, wherein the first and second web portions are opposed in orientation to enable the markers to define the discontinuity.

12. The method of any preceding claim, wherein the markers comprise one or more stripes.

13. The method of Claim 12, wherein each of the web portions comprises first and second parallel stripes.

14. The method of any preceding claim, wherein the first and second web portions are joined at first and second joins and the markers define a contrast about each join.

15. The method of Claim 14, wherein the markers extend between the first and second joins.

16. The method of any preceding claim, wherein the detector captures an image of the discontinuity.

17. The method of Claim 16, wherein the detector comprises a camera.

18. The method of Claim 16 or Claim 17, wherein determining the actual position of the join based on the detected discontinuity comprises: processing said image using contrast recognition software to determine a discontinuity position; and calculating an actual position of the join based on said discontinuity position and a further, fixed comparison position in said image.

19. The method of Claim 18, wherein said comparison position is a leading or trailing edge of a divider supporting the band.

20. The method of any preceding claim further comprising verifying the position of the join by comparing the actual position of the join against a reference position or a reference range.

21. The method of Claim 20, wherein the actual position and the reference position or reference range are compared by a processing unit.

22. The method of Claim 20 or Claim 21 further comprising rejecting the band if the actual position of the join fails to match the reference position or fails to fall within the reference range.

23. The method of Claim 22, wherein rejecting the band comprises removing the band from a band production line.

24. The method of Claim 23, wherein the band is removed from the production line by releasing it from a conveying means and allowing it to fall into a reject area.

25. The method of any of claims Claim 20 to 24 further comprising initiating a recalibration sequence via a control module of a band production line if the band is rejected.

26. The method of Claim 25 further comprising recalibrating a band-forming station and/or a band-repositioning station of the production line if the band is rejected.

27. The method of any of Claims 20 to 26 further comprising stopping a band production line if the band is rejected.

28. The method of any preceding claim wherein the band is provided at a band- forming station by joining the first and second web portions at one or more joins to form a band.

29. The method of any preceding claim further comprising repositioning the join at a join-repositioning station prior to detecting the discontinuity.

30. A system for determining the position of a join in a band for a band-drive article, the system comprising: a band source arranged to provide a band comprising first and second web portions each having a marker and being joined at a join, the markers of the web portions defining a discontinuity about the join;

a detector for detecting the discontinuity; and

a processing unit for determining an actual position of the join based on the detected discontinuity.

31. The system of Claim 30 wherein the band source comprises a band-forming station having first and second marked web feeds and a welding and cutting head for joining and cutting the first and second web feeds at the join to form the band.

32. The system of Claim 30 or Claim 31 , wherein the detector comprises a camera.

33. The system of any of Claims 30 to 32, wherein the discontinuity defines a contrast and the processing unit comprises contrast recognition software.

34. The system of any of Claims 30 to 33 further comprising a join-repositioning station for repositioning the join of the band.

35. The system of any of Claims 30 to 34, wherein the processing unit is programmed to verify the actual position of the join against a reference position or a reference range.

36. The system of Claim 35 further comprising a reject station for rejecting the band if the actual position of the join fails verification by the processing unit.

37. The system of any of Claims 30 to 36 further comprising a control module for operatively linking at least the band source and the processing unit.

38. The system of Claim 37, wherein the processing unit is integral with the control unit.

39. A production line comprising a system according to any one of Claims 30 to 38.

40. A band for a band-drive article, the band comprising first and second web portions each having a marker, wherein the first and second web portions are joined at a join and the markers of the web portions define a discontinuity about the join to facilitate detection of the join by a detector.

41. The band of Claim 40, wherein the discontinuity comprises a contrast that is detectable in the electromagnetic spectrum.

42. The band of Claim 41 , wherein the contrast is detectable in the visual spectrum.

43. The band of Claim 41 or Claim 42, wherein the contrast is detectable in the ultraviolet spectrum.

44. The band of any of Claims 40 to 43, wherein the discontinuity is defined between the markers and unmarked portions of the first and second web portions.

45. The band of any of Claims 40 to 44, wherein the discontinuity results from a misalignment of the markers of the first and second web portions.

46. The band of any of Claims 40 to 45, wherein the markers of the first and second web portions abut the join.

47. The band of any of Claims 40 to 46, wherein the markers of the first and second web portions are substantially identical.

48. The band of any of Claims 40 to 46, wherein the markers of the first and second web portions are offset to a lateral side of their associated web portion.

49. The band of Claims 48, wherein the markers of the first and second web portions are offset to opposed lateral sides to define the discontinuity.

50. The band of any of Claims 40 to 49, wherein the first and second web portions are opposed in orientation to enable the markers to define the discontinuity.

51. The band of any of Claims 40 to 50, wherein the markers comprise one or more stripes.

52. The band of any of Claims 40 to 51 , wherein each of the web portions comprises first and second parallel stripes.

53. The band of any of Claims 40 to 52, wherein the first and second web portions are joined at first and second joins and the markers define a contrast about each join.

54. The band of Claims 53, wherein the markers extend between the first and second joins.