WO2019211606A1

WO2019211606A1 - Method, apparatus and system for the printing and varnishing of security documents

Info

Publication number: WO2019211606A1
Application number: PCT/GB2019/051207
Authority: WO
Inventors: Matthew ZARB
Original assignee: De La Rue International Limited
Priority date: 2018-05-02
Filing date: 2019-05-01
Publication date: 2019-11-07
Also published as: GB2579162A; GB201807238D0

Abstract

A method of printing and varnishing security documents is disclosed. The method comprises conveying, in a machine direction by a web-fed or sheet-fed printing machine, a web or sheet comprising a single line of security documents, wherein the width of the web or sheet in a cross direction orthogonal to the machine direction is such that it can accommodate only one security document in said cross direction, and; successively processing the security documents as they are conveyed in the machine direction, wherein the successively processing comprises printing and varnishing of the security documents on the web or sheet. A corresponding printing machine and system are also disclosed.

Description

METHOD, APPARATUS AND SYSTEM FOR THE PRINTING AND VARNISHING OF SECURITY DOCUMENTS

FIELD OF THE INVENTION

This invention is directed to a method, printing machine and system for the printing and varnishing of security documents. The invention has particular application in the numbering, varnishing and general“finishing” of banknotes.

BACKGROUND TO THE INVENTION

In conventional banknote production, polymer or paper substrates are provided with print workings, typically in the form of complex patterns or images, with each banknote of a denomination being provided with the same print workings. Each banknote is then provided with a unique serial number to increase security and difficulty of counterfeiting, before being varnished to increase the durability of the banknote.

The print workings and varnish are typically performed in a web-fed or sheet-fed process for efficiency of printing, as is known in the art. However, in such processes, there will typically be a few banknotes that are printed incorrectly (“spoiled”) and thus not suitable for public circulation. In web-fed and sheet-fed printing processes, it is difficult to provide individual numbers to banknotes on a web or sheet where some of the banknotes are spoiled without creating an unacceptable amount of waste. This is particularly the case where sequential numbering of the banknotes is desired.

Figure 1 is a schematic view of a sheet 5 comprising a plurality of banknotes 1 that have been provided with print workings but are yet to be numbered and varnished. Here, the sheet 10 shown in Figure 1 comprises 12 banknotes arranged in a matrix of three columns (or“traverses”) and four rows, although typically such sheets may contain between 45 and 60 banknotes.

Conventionally, the individual banknotes 1 on the sheet 10 may be numbered and varnished on the sheet before cutting the sheet into the plurality of single banknotes. However, in this particular sheet 5, let us suppose that an individual banknote (indicated at 1’) has been determined as not meeting the required print quality following the print workings (i.e. it is a“spoiled” banknote). Therefore, although this banknote will be numbered whilst on the sheet, it is not suitable for use as a finished banknote.

However, when cutting the sheet 5 into individual banknotes, it is very difficult, and overly time consuming, to individually single out the spoiled banknote(s) and remove them from the production line. Therefore, in conventional practice, if a spoiled banknote is detected, the whole sheet may be confined to waste before the numbering process. Even if some individual banknotes on such a spoiled sheet are not to be wasted, these are typically limited to single traverses of the sheet rather than each individual banknote that was not spoiled. There is therefore a large amount of waste attributed to such a process.

Furthermore, even if the individual banknote T were to be successfully removed after cutting of the sheet following numbering, the finished batch of banknotes will not be sequentially numbered. Sequential numbering is desirable in many applications, and state-of-the-art methods of providing sequentially numbered banknotes in the case where one of the banknotes is spoiled (for example printing individual banknotes with the“missing” number) are unacceptably time consuming and laborious. The same problems apply to web-based printing.

SUMMARY OF THE INVENTION

In accordance with a first aspect of the present invention there is provided a method of printing and varnishing security documents, comprising: conveying, in a machine direction by a web-fed or sheet-fed printing machine, a web or sheet comprising a single line of security documents, wherein the width of the web or sheet in a cross direction orthogonal to the machine direction is such that it can accommodate only one security document in said cross direction, and; successively processing the security documents as they are conveyed in the machine direction, wherein the successively processing comprises printing and varnishing of the security documents on the web or sheet. The inventors have realised that the efficiency of security document printing and varnishing can be increased using a web or sheet comprising a single line of documents. This is a counter-intuitive solution which goes against conventional approaches of increasing the number of traverses (and therefore security documents) on a web or sheet in attempts to increase efficiency.

The printing of security documents here generally comprises printing unique works on each banknote for security purposes, and is typically performed subsequent to print workings that are common to each security document. Such unique works may comprise information unique to each document in order to increase security, such as numbers, codes or indicia for example. Particularly preferably, the printing in the context of the present invention comprises numbering of the security documents.

The use of such a single line of security documents on a web or sheet allows the security documents to be successively processed by the printing machine. Not only does this allow for the printing and varnishing to be performed at web or sheet printing speed, but also allows for increased ease of producing sequentially numbered security documents in the case where the printing comprises numbering. This is because the successive processing of the security documents allows banknotes that have been “spoiled” by earlier printing processes to be identified and not numbered. By only numbering the good security documents in the successive processing, sequential numbering is easily performed. This is in contrast to conventional processes using webs or sheets with a plurality of traverses, where identification and subsequent removal of spoiled documents is difficult and produces an unacceptable amount of waste.

The term“security document” is used here to refer to security documents at all stages of their printing and finishing processes.

The terms“web-fed” and“sheet-fed” have their conventional meanings as are understood in the art. Web-fed processes use a continuous substrate running through a machine, and are very fast in comparison to sheet-fed processes, which can typically officer higher accuracy.

The web or sheet comprising a single line of security documents is conveyed in a machine direction. Here the term“machine direction” is used to describe the direction in which the web or sheet moves through the printing machine.

The width of the web or sheet in a cross direction orthogonal to the machine direction is such that it can accommodate only one security document in said cross direction. The width of the web or sheet may be substantially equal to a dimension of a security document in that direction such that there is no excess web or sheet material in the cross direction. This advantageously reduces waste. In other embodiments, the width of the web or sheet may be greater than a dimension of a security document in that direction such that there is a“border” of web or sheet material adjacent to the security documents. However, the width of the web or sheet is such that only one security document may be accommodated in that direction.

As the width of the web or sheet in the cross direction is orthogonal to the machine direction, this provides the advantageous effect of the security documents being processed in a successive manner. In other words, the security documents on the web or sheet may be processed one by one (i.e. in turn).

As the web or sheet comprises a single line of security documents, it is typically elongate, and the machine direction is along the direction of elongation.

The method preferably further comprises, prior to the printing of the security documents, determining whether each of the security documents meets a first predetermined quality threshold. This step, in combination with the successive processing of the security documents, advantageously allows for ease of waste removal, as security documents not meeting the first quality threshold can be identified and subsequently removed. This allows identification and removal of individual security documents, rather than conventional techniques of wasting a whole sheet or plurality of security documents in the case that one document is spoiled.

The first predetermined quality threshold is typically a print quality threshold relating to print workings that have been provided to the security documents before subsequent printing (e.g. numbering) and varnishing according to the invention. For example, if a print working on a banknote is determined not to meet the predetermined quality threshold, then that banknote is identified and later separated from the remainder of the security documents.

The print quality threshold may comprise a dimension metric such as a registration metric (e.g. whether the print working is in the correct location), or print line width. Other metrics that may be used alternatively or in addition include a determination of whether a feature is present or absent.

In the case where the security documents comprise a machine detectable feature, the predetermined first quality threshold may be based at least partly on whether a signal strength from such a feature (e.g. magnetic signal strength) meets a predetermined threshold.

Conventional printing methods may identify documents on a conventional web or sheet not meeting such a quality threshold. However, as discussed above, when such a conventional web or sheet is used, processing of any such spoiled security documents typically leads to an unacceptable amount of wastage. In the present invention, the successive processing of a single line of security documents allows for reduced wastage, especially when sequential numbering is desired. In fact, the present invention provides a less complex solution for the printing and varnishing of security documents due to the successive nature of the processing, in contrast to systems that need to process a large number of security documents positioned at different locations on a large web or sheet.

The determination of whether each of the security documents meets a first predetermined quality threshold may be performed upstream (i.e. before) of the printing and vanishing processes. This determination may be performed by an upstream printing machine that provides initial (generic) print workings to the security documents, or by a sheet inspection machine for example. The identification of the security documents that do not meet the first predetermined quality threshold may then be communicated to the web-fed or sheet-fed machine used for printing and varnishing (by a suitable wired or wireless link), and these identified security documents can subsequently be separated from the remainder of the“good” documents.

Alternatively or in addition, the step of successively processing may further comprise inspecting individual security documents on the web or sheet in order to determine whether each of the security documents meets the first predetermined quality threshold. This inspection is preferably performed by a camera system. Such a camera system is typically configured to inspect both the recto and verso sides of each security document, and may comprise first and second cameras for inspection of the recto and verso sides respectively. Alternatively, the camera system may comprise a single camera and means for moving the camera relative to the web or sheet in order to inspect both sides (e.g. flipping the web or sheet, or moving the camera). The successive inspection of the security documents on the web or sheet (due to the single line of documents) advantageously allows for inspection of single security documents at speed (e.g. 400m/min for web speeds) in contrast to conventional inspection methods that handle single banknotes.

In a particularly preferred embodiment, the step of successively processing the security documents comprises printing only the security documents that meet the first predetermined quality threshold. In this way, only the“good” security documents (i.e. the ones meeting the first predetermined quality threshold) are printed. For example, where the printing comprises numbering, as the security documents are successively processed, if a document not meeting the quality threshold is identified, then that document will not have a number printed on to it, and can subsequently be separated from the“good” security documents that have been numbered. Security documents identified as not meeting the first quality threshold do not need to be physically marked as such. Due to the single line of security documents on the web or sheet and their successive processing, the position of the“spoiled” security documents on the web or sheet is easily identified such that they are not printed (e.g. numbered).

Particularly preferably, where the printing comprises numbering, successively numbered security documents on the web or sheet are numbered with consecutive numbers. This beneficially significantly increases the ease of providing a plurality of security documents numbered in a consecutive manner, whilst simultaneously reducing waste.

The printing may be performed by a printing press such as a letterpress. Alternatively or additionally, the numbering may be performed by digital printing, preferably inkjet printing or laser printing. Digital printing advantageously provides a more compact printing machine, and provides high quality printing results as the ink weight can be controlled and there are no mechanical parts.

In embodiments, the method may further comprise the step of, subsequent to the printing of the security documents, determining whether each printed security document meets a second predetermined quality threshold. Typically, such a second predetermined quality threshold is a print quality threshold to ensure that, for example, numbers are printed to the desired quality (e.g. correct line widths and registration). Preferably, the determination as to whether each security document meets the second predetermined quality threshold is performed by inspecting each security document using a camera system configured to inspect each side of the security document which has been printed.

Preferably, the determination of whether each printed document meets a second predetermined quality threshold is performed immediately after printing of a document such that, should a printed document not meet the threshold, the security document to be printed next (i.e. next in line on the web or sheet) can receive the print (e.g. number) of the document that did not meet the threshold. In this manner, consecutive numbering of the security documents can be realised.

After the security documents have been printed, they are varnished, either by conventional or digital methods. For example, the varnish may be applied through traditional flexography, or digitally via an inkjet process. The varnish is typically provided to both the recto and verso sides of the security documents, either by respective varnishing units or by flipping the security documents between varnish applications to each side. The varnishing takes place while the security documents are still on the web or sheet, with each security document being successively varnished as the web or sheet moves along the machine direction. This varnish may comprise a matting additive to reduce the gloss of the security document, i.e. the varnish will reduce the amount of light reflected by the surfaces of the document’s layers. Additionally, the varnish may optimise that when the documents are stacked together they do not stick together. In other words, the varnish will help prevent the security documents from sticking together when stacked or manipulated.

In embodiments, the method may further comprise, subsequent to the printing and varnishing of the security documents on the web or sheet; cutting the web or sheet into a plurality of single security documents. This step is performed by a suitable cutting unit. In addition to the reduced amount of waste and the ease of consecutive numbering of security documents, the present invention also allows for increased simplicity of cutting the web or sheet into individual single security documents. This is due to the fact that a web or sheet comprising a single line of security documents may be cut along a single direction along the width of the web or sheet (orthogonal to the machine direction), rather than having to accurately cut a web or sheet having a plurality of security documents arranged as an m x n matrix.

Preferably, subsequent to the cutting of the web or sheet into a plurality of single security documents, the method may further comprise separating the security documents that met the first and/or second predetermined quality threshold from the security documents that did not meet the first and/or second predetermined quality threshold. In other words, the method further comprises the step of segregating the“spoiled” or“waste” security documents from the good ones. The“spoiled” or“waste” security documents may typically be routed differently to the “good” security documents. This may typically be performed by an air separator for example, although other means of separation of the “spoiled” security documents from the “good” documents are envisaged, for example destroying the“spoiled” security documents in line.

Due to the successive processing of the security documents, security documents that were identified as not meeting at least one of the first and second predetermined quality thresholds are easily separated with minimal wastage of material. Furthermore, should it be desired, the remaining “good” security documents are easily provided with consecutive numbers.

In embodiments, the method further comprises the step of grouping single security documents into groups. For example, in the case of bank notes, the single“good” banknotes may be banded into groups of 100.

In embodiments, the method further comprises the step of packing the single security documents. This may comprise packing individual security documents, or packing groups of security documents.

Therefore, the method of the first aspect of the invention may be seen as providing a complete“finishing” process for security documents requiring printing (e.g. numbering) and varnishing, for example banknotes. Due to the ability to successively process the security documents on a web or sheet, the steps of printing, varnishing, and optionally inspection, cutting, separating, grouping and packing can be performed by a single“finishing” machine that is able to provide these“finishing” steps at web or sheet speeds, with minimal wastage or material, and ease of consecutive numbering if desired.

The method may further comprise the initial steps of: receiving a master web or sheet comprising a plurality of security documents arranged in a matrix of rows and columns, and; cutting the master web or sheet into a plurality of respective webs or sheets, each web or sheet comprising a single line of security documents, wherein a width of the web or sheet in a cross direction orthogonal to a subsequent machine direction is such that it can accommodate only one security document in said cross direction. The master web or sheet typically comprises a plurality of security documents arranged in a plurality of traverses and having generic (i.e. the same) print workings thereon, and which are to be numbered and varnished.

The cutting of such a master web or sheet into a plurality of respective webs or sheets comprising a single line of security documents is generally referred to as “slitting”, where the web is cut or divided longitudinally, i.e. along the machine direction. The subsequent webs or sheets comprising single lines of documents may then be fed into a respective web-fed or sheet-fed finishing machine and processed as described above. If the number of finishing machines is the same as the number of traverses on the master web or sheet, then the“finishing” processing of the security documents may advantageously continue at the web or sheet speed.

In accordance with a second aspect of the invention there is provided a web-fed or sheet-fed printing machine for printing and varnishing security documents, comprising: a feed unit configured to convey, in a machine direction, a web or sheet comprising a single line of security documents, wherein the width of the web or sheet in a cross direction orthogonal to the machine direction is such that it can accommodate only one security document in said cross direction, and; processing means configured to successively process the security documents as they are conveyed in the machine direction, wherein the processing means comprises; a printing unit configured to print the security documents on the web or sheet, and; a varnishing unit configured to varnish the security documents on the web or sheet.

Preferably, the printing unit comprises a numbering unit configured to number the security documents on the web or sheet. The web-fed or sheet-fed printing machine of the second aspect of the invention provides the same advantages as the method of the first aspect of the invention. Due to the processing means being configured to successively process the security documents as they are conveyed in the machine direction (as a result of the single line of security documents on the web or sheet), wastage in the case of spoiled security documents is significantly reduced, and consecutive numbering of security documents, should it be desired, is made significantly easier.

Preferably, the processing means further comprises an inspection unit positioned upstream of the printing unit and configured to determine whether each of the security documents meets a first predetermined quality threshold. This inspection unit typically comprises a camera system. Such a camera system is typically configured to inspect both the recto and verso sides of each security document, and may comprise first and second cameras for inspection of the recto and verso sides respectively. Alternatively, the camera system may comprise a single camera and means for moving the camera relative to the web or sheet in order to inspect both sides (e.g. flipping the web or sheet, or moving the camera).

The first predetermined quality threshold is typically a print quality threshold relating to previous print workings that have been provided to the security documents before printing and varnishing by the machine of the second aspect of the invention. In the case where the security documents comprise a machine detectable feature, the predetermined first quality threshold may be based at least partly on whether a signal strength from such a feature (e.g. magnetic signal strength) meets a predetermined threshold.

In other embodiments, the web-fed or sheet-fed printing machine may be in communication with an upstream printing machine that provided print workings to the security documents, or a sheet inspection machine, wherein the upstream printing machine or sheet inspection machine identifies security documents not meeting the first predetermined quality threshold and communicates these to the printing machine of the second aspect. The communication may be over a wired or wireless communication link.

In preferred embodiments, the printing unit is configured to number only the security documents that meet the first predetermined quality threshold. In this way, only the “good” security documents (i.e. the ones meeting the first predetermined quality threshold) are printed (e.g. provided with numbers). For example, in the case of numbering, as the security documents are successively processed, if a document not meeting the quality threshold is identified, then that document will not have a number printed on to it, and can be later separated from the“good” security documents that have been numbered.

Security documents identified as not meeting the first quality threshold do not need to be physically marked as such. Due to the single line of security documents on the web or sheet and their successive processing, the position of the“spoiled” security documents on the web or sheet is easily identified by the inspection unit such that they are not printed by the printing unit (e.g. numbered).

Typically the printing unit comprises a printing press such as a letter press, or a digital printing means, preferably an inkjet printer or a laser printer. The printing unit is typically configured for printing on both the recto and verso sides of a security document. For example, the printing unit may comprise first and second printing sub-units for the recto and verso sides respectively, or may comprise means for flipping the security document such that both sides thereof may be printed.

The varnishing unit may be configured to apply the varnish using digital or conventional techniques. The varnish is typically provided to both the recto and verso sides of the security documents. The varnishing takes place while the security documents are still on the web or sheet, with each security document being successively varnished as the web or sheet moves along the machine direction. The varnishing unit may comprise first and second varnishing sub units for varnishing the recto and verso sides of the security documents respectively, or may comprise means for flipping the security documents such that varnish may be applied to both sides.

In particularly preferred embodiments, where the printing unit comprises a numbering unit, the numbering unit is configured to provide consecutive numbers to successively numbered security documents. This beneficially significantly increases the ease of providing a plurality of security documents numbered in a consecutive manner, whilst simultaneously reducing waste.

In embodiments, the processing means further comprises a secondary inspection unit configured to determine whether each printed (e.g. numbered) security document meets a second predetermined quality threshold. Typically, such a second predetermined quality threshold is a print quality threshold to ensure that the security documents are printed to the desired quality. Preferably, the determination as to whether each printed security document meets the second predetermined quality threshold is performed by inspecting each security document using a camera system configured to inspect each side of the security document which has been printed (for example with a number).

Preferably, the secondary inspection unit is configured to determine whether each printed document meets a second predetermined quality immediately after printing of a document such that, should a printed document not meet the second print quality threshold, the security document to be printed (e.g. numbered) next can receive the print (e.g. number) of the document that did not meet the threshold. In this manner, consecutive numbering of the security documents can be realised. The secondary inspection unit preferably comprises a camera system configured to inspect each side of a security document that has been printed by the machine.

The web-fed or sheet-fed printing machine may further comprise a cutting unit positioned downstream of the printing and varnishing units, and configured to cut the web or sheet into a plurality of single security documents. The present invention allows for increased simplicity of cutting the web or sheet into individual single security documents. This is due to the fact that a web or sheet comprising a single line of security documents may be cut along a single direction along the width of the web or sheet (orthogonal to the machine direction), rather than having to accurately cut or web or sheet having a plurality of security documents arranged as an m x n matrix.

The printing machine may further comprise a separation unit configured to separate the security documents that met the first and/or second predetermined quality threshold from the security documents that did not meet the first and/or second predetermined quality threshold. Such a separation unit is typically an air separator, although other means of separating the security documents are envisaged. In some embodiments, after cutting, the“spoiled” documents may be destroyed in line.

The printing machine may further comprise a grouping unit configured to group single security documents into groups.

The printing machine may further comprise a packing unit configured to pack the single security documents.

The printing machine of the second aspect of the invention is preferably modular in construction, and could comprise further units, for example a press adapted to emboss the security documents in order to generate a tactile feature.

The printing machine typically comprises suitable software and a processor for control of the components of the printer.

In accordance with a third aspect of the invention there is provided a system for printing and varnishing security documents, comprising: a first cutting apparatus configured to: receive a master web or sheet comprising a plurality of security documents arranged in a matrix of rows and columns, and; cut the master web or sheet into a plurality of respective webs or sheets, each web or sheet comprising a single line of security documents, wherein a width of the web or sheet in a cross direction orthogonal to a subsequent machine direction is such that it can accommodate only one security document in said cross direction, and wherein; the system further comprises a printing machine of the second aspect located downstream of the first cutting apparatus. The master web or sheet typically comprises a plurality of security documents having generic print workings thereon, and which are to be uniquely printed (e.g. numbered) and varnished by the printing machine of the second aspect of the invention.

In accordance with a fourth aspect of the invention there is provided a system for manufacturing security documents, comprising: a first web-fed or sheet-fed printing machine configured to print a plurality of security documents arranged in a matrix of rows or columns on a web or sheet, and; a system for printing and varnishing security documents according to the third aspect of the invention.

A system as in the fourth aspect of the invention allows the printing and finishing of security documents on a web or sheet in substantially one pass, thereby advantageously increasing the speed at which security document production and the final printing (e.g. numbering) and varnishing steps (as well as other “finishing” steps such as inspection cutting, grouping and banding) can be performed at web or sheet speed. In such a system, the printing machine of the second aspect of the invention may be referred to as a“finishing” machine.

Due to the slitting of the master web or sheet into webs or sheets comprising a single line of security documents, in order to maintain the web or sheet printing speed for the entirety of the production process, a system according to the fourth aspect preferably comprises a plurality of finishing machines corresponding to the number of webs or sheets following slitting of the master web or sheet, i.e. the number of finishing machines corresponds to the number of traverses on the master web or sheet. However, the finishing machines are compact, and so such an arrangement does not use up excessive production floor space.

The present invention may be used in relation to any type of security document, but has particular application for banknotes. The banknotes may have a paper substrate (i.e. the web or sheet is formed of paper). In other embodiments, the banknote substrate comprises a plastic material, such as: polyethylene terephalate (PET), biaxially orientated polypropylene (BOPP), polycarbonate (PC), polyvinylchloride (PVC), polybutlylene terephalate (PBT), nylon or acrylic.

In accordance with a fifth aspect of the invention there is provided a computer readable medium comprising executable instructions that when executed by a processor cause a printing machine to perform the method of the first aspect.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred embodiments of the invention will now be described with reference to the attached drawings, in which:

Figure 1 is a schematic illustration of a sheet of security documents used in conventional printing techniques;

Figure 2 schematically illustrates a portion of a web of banknotes that may be used in the present invention;

Figure 3 is a flow diagram outlining the main steps of a preferred embodiment of the invention;

Figure 4 is a schematic diagram of a printing machine according to an embodiment of the invention, and;

Figure 5 is a schematic diagram of a system according to an embodiment of the invention.

DETAILED DESCRIPTION

The following description will be in relation to web-based printing, although it will be appreciated that the invention is also applicable to sheet-based printing. The following description will also refer to providing serial numbers to banknotes, although it will be appreciated that the invention is also applicable to printing of other security documents.

Figure 2 schematically illustrates a portion of a web 10 of banknotes (1 a, 1 b...1 f) that may be used in the present invention. As can be seen, in contrast to the sheet 5 seen in Figure 1 where the banknotes were arranged as an m x n matrix comprising a plurality of traverses, the individual banknotes carried by the web 10 of Figure 2 are arranged as a single line. In other words, the width of the web 10 is substantially equal to the width of an individual banknote. Here, both the width of the web 10 and the width of an individual banknote 1 is its respective dimension along the x axis. In this example the web comprises a polymer material such that the banknotes have a polymer substrate. In other examples, the web may comprise a paper material.

The web 10 is configured to be fed into a printing machine 100 (see Figure 4) for numbering and varnishing. The web 10 is fed into the machine 100 along a machine direction, as illustrated in Figure 2. Here the machine direction is parallel to the direction in which the line of individual banknotes is formed (here along the y axis). The machine direction is orthogonal to the width of the web 10.

In general, the web for use in the present invention has a width in a cross direction orthogonal to the machine direction such that it can accommodate only one banknote in said cross direction. The dashed line indicated at 10a in Figure 2 illustrates an alternative web 10a which has a border of excess material (illustrated at 1 1 ) surrounding the individual banknotes. However, the width of the alternative web 10a is such that it can only accommodate one banknote along its width.

Advantageously, the use of such a single line of security documents on a web means that the printing machine 100 can process each individual banknote successively (i.e. in turn), which consequently allows for increased ease of separation of spoiled banknotes with minimal wastage, with the further advantage of increasing the ease of providing a plurality of banknotes numbered with sequential numbers. This process will now be described with reference to the flowchart illustrated in Figure 3.

At step S101 , the web is received at a web-based printing machine 100 (see Figure 4) configured to perform numbering and varnishing together with further finishing processes, as will be described below. The web comprises a plurality of banknotes arranged in a single line as described above, with the banknotes having print workings thereon (e.g. intaglio and lithographic print workings applied by a previous printing process). The web is received along a machine directed which is orthogonal to the width of the web.

At step S102, it is determined whether each banknote meets a first predetermined print quality threshold in relation to the print workings. This is typically performed by a camera system that inspects each banknote on the web in turn. Advantageously, due to the arrangement of the single line of banknotes on the web, such a camera system may inspect each banknote in a successive manner. For example, referring back to Figure 2, with the web moving in the machine direction indicated, such a camera system would inspect banknote 1 a, followed by 1 b, followed by 1 c etc. The camera system comprises a first camera positioned for inspection of the recto side of a banknote, and a second camera positioned for inspection of the verso side of the banknotes.

In an alternative example, the previous printing process may have identified individual spoiled banknotes and communicated this data to printing machine 100 such that these banknotes may be identified by the printing machine 100. The data may be communicated over a suitable wired or wireless network.

Suitable metrics for determining whether a banknote meets the print quality threshold include a registration metric (e.g. whether the print working is in the correct location) a print line width and a determination of whether or not a feature is present.

In the case where the security documents comprise a machine detectable feature, step S102 may further comprise determination of whether a signal strength (e.g. magnetic signal strength) of said feature meets a predetermined threshold.

If a banknote does not meet the first predetermined print quality threshold, then no serial number is printed on that banknote (step S104). If, on the other hand, the banknote does meet the first predetermined print quality threshold, the process moves to step S103 where a serial number is printed on the banknote. This step is performed by a printing unit located downstream from the inspection unit (if present) and may be in the form of a printing press (such as a letterpress) or digital printing means (such as an inkjet or laser printer).

At step S105, a determination is made as to whether the numbering performed in step S103 meets a second predetermined print quality threshold. In a similar manner to step S102, this is performed by a camera system. The determination of whether the numbering meets the second predetermined quality threshold is performed immediately after said numbering such that, should a printed banknote not meet the threshold in step S105, the banknote to be numbered next on the web can receive the number of the banknote that did not meet the second predetermined print quality threshold. In this manner, sequential numbering of the banknotes can be performed.

Referring back to Figure 2, let us suppose that banknote 1 d was determined not to meet the first predetermined print quality threshold at step S102, and consequently did not have a serial number printed thereon (step S104). Therefore, banknotes 1 a, 1 b, 1 c, 1 e, 1f (which all met the first print quality threshold) proceeded to step S105. Now suppose that banknote 1 e was numbered but did not meet the second print quality threshold at step S105 as its number was printed erroneously. In this case, the following banknote to be processed - banknote 1f - would be printed with the number originally assigned to banknote 1 e. In this manner, banknotes 1 a, 1 b, 1 c and 1f are advantageously numbered in a sequential manner as they were successively processed in the machine direction.

Following the numbering, at step S106, the banknotes are varnished on the web. The machine 100 is configured to varnish the recto and verso sides of the banknotes, and may provide the varnish by traditional flexography or by an inkjet process.

Following varnishing, the web 10 is cut into single banknotes at step S107.

At step S108, it is determined whether or not the each banknote met both the first and second predetermined print quality thresholds. If a banknote did not meet either the first predetermined quality threshold (step S102) or the second predetermined quality threshold (step S105), that banknote is separated from the remaining “good” notes that met both thresholds, and sent to waste at step S109. Such separation is typically performed by an air separator for example. Therefore, in this worked example, banknotes 1 d and 1 e are separated from banknotes 1 a, 1 b, 1 c and 1 f and sent to waste at step S109.

Conversely, the“good” banknotes (which are now sequentially numbered) are then banded at step S1 10, typically into bands of 100 banknotes, before being packed at step S1 1 1 , typically into packs of 1000 notes.

Figure 4 schematically illustrates such a web-based printing machine adapted for performing the steps illustrated in the flowchart of Figure 3. As can be seen in Figure 4, a web 10 comprising a single line of banknotes (as described above) is supported on a cassette 15 and introduced to a feed unit 1 10, which conveys the web along the machine direction.

The machine 100 comprises an inspection unit 120 configured to determine whether each banknote meets the first predetermined print quality threshold (step S102). The first inspection unit is typically in the form of a camera system, comprising a first camera for inspection of the recto side of the banknotes, and a second camera for inspection of the verso sides of the banknotes, although other means of note inspection may be performed.

In an alternative example, the inspection unit 120 does not comprise a camera system but is configured to receive information relating to whether or not each banknote met the predetermined print quality. This may be obtained from a previous printing or sheet inspection machine that applied the print workings to the banknotes for example. In such a case, the inspection unit and the previous printing machine may be in communication via a wired or wireless communications network. In some examples the first inspection unit may comprise both a camera system and be configured to receive print quality information. A printing unit 130 is configured to number each banknote that met the predetermined quality threshold (step S103). Due to the single line arrangement of the security documents on the web, this allows for sequential numbering of good banknotes. The printing unit is also adapted to not number any banknote that did not meet the predetermined print quality threshold as determined by the inspection unit 120.

The printing machine 100 further comprises a second inspection unit 135 configured to determine whether the numbering performed by the printing unit 130 meets a second predetermined quality threshold (step S105). The second inspection unit is typically in the form of a camera system for inspection of each side of the banknote that was numbered. The second inspection unit may be integrated with the printing unit 130 such that, should a banknote not meet the second print quality threshold, the next banknote to be successively processed may be printed with the number originally intended for the banknote that did not meet the second print quality threshold.

Each banknote on the web (whether or not it was numbered and whether or not it met the second print quality threshold) is then varnished at varnishing unit 140 (step S106). The varnishing unit is configured to apply a layer of varnish to both the recto and verso sides of the numbered banknotes. This may be performed by a first varnishing sub-unit configured to apply varnish to the recto side of the banknotes and a second varnishing sub-unit configured to apply varnish to the verso sides. In an alternative example, the banknotes may be flipped such that varnish is applied to both sides.

A cutting unit 150 is positioned downstream of the varnishing unit and is configured to cut the numbered and varnished web into individual banknotes (step S107). A separator unit 160 then separates the waste banknotes from the good banknotes (which met both print quality thresholds). The separator unit is typically in the form of an air separator, although other means of separation of the banknotes are envisaged as are known in the art. A banding unit 170 subsequently bands the good banknotes into groups of 100 (step S1 10), before a packing unit 180 packs the banded banknotes (step S1 1 1 ).

The machine 100 is modular in construction, and could comprise further units, for example a press adapted to emboss the banknotes in order to generate a tactile feature.

Due to the web-fed nature of the machine 100, the machine is advantageously able to work at web speeds for printing (typically -400 metres per minute) in contrast to conventional single note numbering solutions which handle single banknotes with a consequent dramatic reduction in speed in comparison to web- or sheet-based printing.

Figure 5 schematically illustrates a system 1000 for manufacturing a plurality of banknotes according to the present invention. Here, a substrate web 20 carrying a plurality of banknotes in the form of an m x n matrix may first be provided with print workings in a first web-fed printing process (generally illustrated at 1 100). More specifically, in this example a reel of a substrate web 20 is provided with a plurality of banknotes arranged in the form of three traverses. In this example, the substrate web is a polymer web, although other substrate materials may be used, such as paper. A typical width for the substrate web (i.e. the combined width of all three traverses) is 500mm.

In this example, the banknotes of the substrate web go through lithographic and intaglio printing processes (shown at 1001 , 1002 and 1003) to provide the desired print workings on the recto and verso sides of the substrate web, although other print processes may be performed. The print workings may typically include any of security prints, guilloches, microtext, and repeating geometric patterns. Such complex workings are difficult for would-be counterfeiters to reproduce. The web 20 then goes through a screen process 1004, for the application of specialist inks such as optically variable inks, before being slit by slitting unit 1005 into the respective webs 10a, 10b, 10c for feeding into respective web-based printing machines 100a, 100b, 100c, each of which being as described above in relation to Figure 4. In the context of the invention, each of these web-based printing machines 100a, 100b, 100c can be seen as a “finishing” machine for finishing of the banknotes.

Each of the slit webs 10a, 10b, 10c, comprises a single line of banknotes. These slit webs 10a, 10b, 10c are then fed into respective web-fed finishing machines 100a, 100b, 100c for numbering, varnishing, cutting, separating, banding and packing as has been explained above in combination with Figures 2 to 4. As the web-based finishing machines 100a, 100b and 100c are configured to receive a web of banknotes, the finishing of the banknotes can be performed at web speeds (up to 400m/min) in line with the printing process outlined at 1 100. In order to maintain the speed of processing of the web, the number of web- based finishing machines 100 corresponds to the number of slit webs and thus the number of traverses in the original web 20. Advantageously, each of the finishing machines 100 is compact (typically of “benchtop” size) and requires minimal space for installation.

It will be appreciated that this invention also applies to sheets that are formed so as to comprise a single line of security documents. Such sheets could be provided by cutting or dividing the substrate web 20 laterally before slitting the resultant sheet into sheets comprising a single line of banknotes. Alternatively, the printing processes 1 100 may be performed in a sheet-fed process rather than a web-fed process, with the printed sheets subsequently slit into individual sheets with a single line of banknotes.

Claims

1. A method of printing and varnishing security documents, comprising: conveying, in a machine direction by a web-fed or sheet-fed printing machine, a web or sheet comprising a single line of security documents, wherein the width of the web or sheet in a cross direction orthogonal to the machine direction is such that it can accommodate only one security document in said cross direction, and;

successively processing the security documents as they are conveyed in the machine direction, wherein the successively processing comprises printing and varnishing of the security documents on the web or sheet.

2. The method of claim 1 , wherein the printing comprises numbering of the security documents.

3. The method of claim 1 or claim 2, further comprising, prior to the printing of the security documents, determining whether each of the security documents meets a first predetermined quality threshold.

4. The method of claim 3, wherein the step of successively processing further comprises inspecting individual security documents on the web or sheet in order to determine whether each of the security documents meets the first predetermined quality threshold.

5. The method of claim 4, wherein the inspection is performed by a camera system.

6. The method of any of claims 3 to 5, wherein the step of successively processing the security documents comprises printing only the security documents that meet the first predetermined quality threshold.

7. The method of any of the preceding claims, wherein the printing is performed by a printing press such as a letterpress.

8. The method of any of the preceding claims, wherein the printing is performed by digital printing, preferably inkjet printing or laser printing.

9. The method of any of preceding claims, wherein the printing comprises numbering of the security documents, and wherein successively numbered security documents on the web or sheet are numbered with consecutive numbers.

10. The method of any of the preceding claims, further comprising, subsequent to the printing of the security documents, determining whether each printed document meets a second predetermined quality threshold.

1 1 . The method of any of the preceding claims, further comprising, subsequent to the printing and varnishing of the security documents on the web or sheet;

cutting the web or sheet into a plurality of single security documents.

12. The method of claim 1 1 when dependent on at least one of claim 3 and claim 10, further comprising, subsequent to the cutting of the web or sheet into a plurality of single security documents;

separating the security documents that met the first and/or second predetermined quality threshold from the security documents that did not meet the first and/or second predetermined quality threshold.

13. The method of claim 1 1 or claim 12, further comprising the step of grouping single security documents into groups.

14. The method of any of claims 1 1 to 13, further comprising the step of packing the single security documents.

15. The method of any of the preceding claims, further comprising the initial steps of:

receiving a master web or sheet comprising a plurality of security documents arranged in a matrix of rows and columns, and; cutting the master web or sheet into a plurality of respective webs or sheets, each web or sheet comprising a single line of security documents, wherein a width of the web or sheet in a cross direction orthogonal to a subsequent machine direction is such that it can accommodate only one security document in said cross direction.

16. A web-fed or sheet-fed printing machine for printing and varnishing security documents, comprising:

a feed unit configured to convey, in a machine direction, a web or sheet comprising a single line of security documents, wherein the width of the web or sheet in a cross direction orthogonal to the machine direction is such that it can accommodate only one security document in said cross direction, and;

processing means configured to successively process the security documents as they are conveyed in the machine direction, wherein the processing means comprises;

a printing unit configured to print the security documents on the web or sheet, and;

a varnishing unit configured to varnish the security documents on the web or sheet.

17. The printing machine of claim 16, wherein the printing unit comprises a numbering unit configured to number the security documents on the web or sheet.

18. The printing machine of claim 16 or claim 17, wherein the processing means further comprises an inspection unit positioned upstream of the printing unit and configured to determine whether each of the security documents meets a first predetermined quality threshold.

19. The printing machine of claim 18, wherein the inspection unit comprises a camera system.

20. The printing machine of claim 18 or claim 19, wherein the printing unit is configured to print only the security documents that meet the first predetermined quality threshold.

21 . The printing machine of any of claims 16 to 20, wherein the printing unit comprises a printing press such as a letterpress or a digital printing means, preferably an inkjet printer or a laser printer.

22. The printing machine of any of claims 16 to 21 , wherein the printing unit comprises a numbering unit configured to provide consecutive numbers to successively numbered security documents.

23. The printing machine of any of claims 16 to 22, wherein the processing means further comprising a secondary inspection unit configured to determine whether each numbered security document meets a second predetermined quality threshold.

24. The printing machine of any of claims 16 to 23, further comprising a cutting unit positioned downstream of the printing and varnishing units, and configured to cut the web or sheet into a plurality of single security documents.

25. The printing machine of claim 24 when dependent on at least one of claim 18 and claim 23, further comprising a separation unit configured to separate the security documents that met the first and/or second predetermined quality threshold from the security documents that did not meet the first and/or second predetermined quality threshold.

26. The printing machine of any of claims 16 to 25, further comprising a grouping unit configured to group single security documents into groups.

27. The printing machine of any of claims 24 to 26, further comprising a packing unit configured to pack the single security documents.

28. A system for printing and varnishing security documents, comprising: a first cutting apparatus configured to:

receive a master web or sheet comprising a plurality of security documents arranged in a matrix of rows and columns, and;

cut the master web or sheet into a plurality of respective webs or sheets, each web or sheet comprising a single line of security documents, wherein a width of the web or sheet in a cross direction orthogonal to a subsequent machine direction is such that it can accommodate only one security document in said cross direction, and wherein;

the system further comprises a printing machine of any of claims 16 to 27 located downstream of the first cutting apparatus.

29. The system of claim 28, wherein the number of printing machines corresponds to the number of sheets or webs comprising a single line of security documents.

30. A system for manufacturing security documents, comprising:

a first web-fed or sheet-fed printing machine configured to print a plurality of security documents arranged in a matrix of rows or columns on a web or sheet, and;

a system for printing and varnishing security documents according to claim 28 or claim 29.

31 . The method, printing machine or system of any of the preceding claims, wherein the security documents are banknotes.

32. A computer readable medium comprising executable instructions that when executed by a processor cause a printing machine to perform the method of any of claims 1 to 15.