EP3113958B1

EP3113958B1 - Method of manufacture of security documents

Info

Publication number: EP3113958B1
Application number: EP15709308.9A
Authority: EP
Inventors: Stephen Banister Green
Original assignee: De la Rue International Ltd
Current assignee: De la Rue International Ltd
Priority date: 2014-03-06
Filing date: 2015-03-02
Publication date: 2018-11-07
Anticipated expiration: 2035-03-02
Also published as: GB2525730B; GB201403988D0; GB2525730A; EP3113958A1; GB201503517D0; WO2015132574A1

Description

This invention relates to security documents such as banknotes, passports, identification cards and the like, and methods for their manufacture. Apparatus for manufacturing the documents is also disclosed.
Secure documents such as passports, banknotes, identification documents, certificates and licences are frequently the target of counterfeiters and persons wishing to make fraudulent changes to the data contained therein. Typically such documents are provided with a number of security elements for checking the authenticity of the document. These may include devices such as holograms or other optically variable elements affixed to the document, elements such as threads or strips incorporated inside the document, and markings such as printing, laser inscription or perforation applied to the substrate. Where the document comprises a fibrous substrate such as paper (optionally forming part of a multi-layered laminate construction with other materials, or a page of a multi-page document such as a booklet), additional security elements may be provided as part of the document substrate itself, such as watermarks and apertures. Some such security elements may themselves contain individualisation information unique to the particular document, e.g. personalisation data relating to an owner of the document (e.g. data giving the owner's name, a photograph or biometric data). In order to determine the authenticity of the document, typically one or more of the security elements are inspected to ascertain whether each provides the expected response or whether the data contained therein corresponds to the person presenting the document, for example.
An example of a security element formed in the fibrous substrate of a security document is disclosed in WO-A-2004/001130 . Here, an elongate element such as a thread or strip is partially embedded in a fibrous substrate and exposed by at least one discrete aperture extending through the substrate. The relative widths of the elongate element and aperture are such that at least one edge of the elongate element, preferably both edges, are exposed in the aperture. This arrangement ensures that the elongate element, which may itself carry indicia or a device such as a hologram, is easily verifiable from both sides of the document.
Persons wishing to produce counterfeits of security documents, or to fraudulently alter data in existing documents, typically attempt to do so by substituting security elements with similar ones obtained from other security documents or, depending on the technologies involved, manufactured themselves or obtained illegally. As the sophistication of such techniques improves, it has become more difficult to detect forgeries since in many cases the substituted security element provides the same or a similar response to that which a person inspecting the document expects. It would therefore be desirable to provide security documents with an increased security level which are more difficult to successfully counterfeit.
Examples of methods for manufacturing security documents may be found in DE 102011103000 A1 , WO 2004/001130 A1 and Rudolf L. van Renesse: "Optical Document Security (Third Edition)", 2005, Artech House, Boston/London, XP002740341, ISBN: 1-58053-258-6, page 78 - page 79 and page 134 - page 135.
DE 10 2011 103000 A1 discloses a method of manufacturing a security document comprising a fibrous substrate, the method comprising: (a) providing a fibrous substrate formed by deposition of fibres onto a porous support, the fibrous substrate comprising a first integral feature formed during the formation of the fibrous substrate, the first integral feature being a window feature comprising: an aperture through at least a portion of the thickness of the fibrous substrate, through which an insert incorporated within the fibrous substrate is exposed, and/or an aperture through the full thickness of the fibrous substrate; (b) detecting from the fibrous substrate the location of the window feature on the fibrous substrate; and (c) applying a security feature to the fibrous substrate and/or the insert at a position referenced to the detected location of the window feature, such that the security feature and the window feature are registered to one another. DE 10 2011 103000 A1 does not disclose the step providing a precursor security document comprising a plurality of joined pages, at least one of the pages comprising a fibrous substrate, because DE 10 2011 103000 A1 only mentions webs, and nothing with joined pages.
In accordance with the present invention, a method of manufacturing a security document comprising a fibrous substrate is provided. The method comprises:

(a) providing a precursor security document comprising a plurality of joined pages, at least one of the pages comprising a fibrous substrate formed by deposition of fibres onto a porous support, the fibrous substrate comprising a first integral feature formed during the formation of the fibrous substrate, the first integral feature being a window feature comprising: an aperture through at least a portion of the thickness of the fibrous substrate, through which an insert incorporated within the fibrous substrate is exposed, and/or an aperture through the full thickness of the fibrous substrate;
(b) detecting from the substrate the location of the window feature on the fibrous substrate; and
(c) applying a security feature to the fibrous substrate and/or the insert at a position referenced to the detected location of the window feature, such that the security feature and the window feature are registered to one another.

By providing the security document with two security elements - e.g. the window feature and the security feature (such as a print or other marking) - in this way, the difficulty of producing an accurate counterfeit is significantly increased and hence the security level of the document is enhanced. The registration between the two elements has the result that, in genuine specimens of the document, the window feature and the security feature will always exhibit a particular, pre-determined positional relationship to one another. Thus in order to produce a replica, the counterfeiter must not only master both the paper-making technology required to produce the window feature and the different techniques needed to form the security feature, but must also form the two elements in the same positions relative to one another as demanded by the genuine document. This is particularly challenging as compared with registering two features which are both applied to the finished substrate (such as two printed workings), since the window feature and applied security feature cannot be manufactured in one, continuous in-line process. Hence the requirement for registration presents a difficult technical challenge and thus a significant obstacle to the counterfeiter.
By an "integral" feature it is meant a feature which is created during the formation of the fibrous substrate (e.g. during papermaking), as opposed to one which is applied to the finished substrate (e.g. prints or transfer elements). Various examples of such integral features will be described below, but as indicated above, the first integral feature is of a particular type, namely a window feature which comprises either an aperture through the full thickness of the fibrous substrate, or an aperture exposing an insert incorporated within the fibrous substrate, or both.
It should be appreciated that in order for the register between the two security elements to be effective, those two security elements must each remain visible (or at least machine-detectable) in the finished document. Therefore, the security feature applied in step (c) should preferably not conceal the full periphery of the window feature if it is the registration between the window feature and the security feature which is desired to be shown. If some other integral feature is provided in the paper against which the registration is to be demonstrated (discussed below), then this is optional.
It should be noted that a window feature of the sort described will typically have different physical characteristics from those of an aperture formed in the substrate after its formation, e.g. by cutting, stamping or abrasion, and can thus be distinguished from such apertures by inspection. For example, a window feature formed during formation of the fibrous substrate will typically have irregular edges which expose individual fibres or bunches of fibres, and/or a finite region surrounding the aperture in which the fibre density of the substrate is lower than that of the main body of the substrate. The detailed shape of the window periphery will generally also change from one document to the next, since this is determined to an extent by the arrangement of fibres, which will be random. In contrast, the edges of an aperture formed after papermaking will typically be well-defined and generally closely follow a pre-determined shape, such as a circle.
It will be appreciated that such integral features, formed during the papermaking process, are likely to deviate slightly in their precise position on the substrate either relative to the desired template position (e.g. as measured from the edge of the substrate) and/or from document to document. The variations in the position of integral features formed in the papermaking process are a result of number of distortion factors. During the fibre deposition process, once fibres have been deposited in accordance with the desired template, as they are subsequently dried, the substrate will distort slightly, primarily due to shrinkage. The degree of shrinkage at the edge of the paper web is generally greater than in the centre, with the result that documents cut from the edge of the sheet may carry their integral feature(s) at a slightly different position from that exhibited in documents cut from the centre of the sheet. Additionally, the degree of shrinkage may vary according to a number of variables, including the particular machine, wetness, type of stock and processing speed used in the paper formation process. Furthermore, during papermaking, the sheet size is monitored and if necessary the paper is stretched in the machine direction to ensure the dimensional specification is met. This will also affect the position of the integral paper features. Even once the paper is made, there may be expansion of the paper due to the humidity in the atmosphere that will affect the location of the integral features. This will of course depend to what level the paper was dried in the first place.
This variation in position of integral features can have a negative effect on the accuracy of any visual display of registration, for example, between a window feature and a security feature which is added to the substrate after the substrate has been made, especially when the placement position of the security feature is being determined under the assumption that the position of the integral feature is correctly and precisely predicted by a template. It is therefore common practice to use a tolerance, for example ±3 mm, for the location of integral features with reference to a template, and to apply subsequent security features in accordance with this tolerance. This means that the actual relative distance between the integral feature and the security feature on the finished document may vary by up to twice the tolerance (e.g. up to 6mm) from one document to another. In contrast, the present invention provides the steps of detecting from the substrate the location of the window feature on the substrate prior to application of a security feature, and subsequently applying the security feature with reference to the detected location of the window feature. This enables the registration between the security feature and the window feature to be effected more accurately and precisely.
The registering of the security feature to a window feature formed during formation of the fibrous substrate provides two further particular benefits. Firstly, since the window feature is either a full-thickness aperture or exposes an insert (such as a thread) incorporated within the fibrous substrate, the window feature can be readily detected in step (b) due to the significant difference between the characteristics of the window feature and those of its surroundings. For example, there is preferably a visible contrast between the window feature and its surroundings on the fibrous substrate, due either to the window feature being a gap in the substrate (hence exposing for example some underlying surface which can be arranged to be a different colour from the substrate), or to the window feature exposing an insert which will typically also have a different appearance from the fibrous substrate. For example, the insert may be reflective, metallic, transparent or coloured and will generally be of a different material to that of the fibrous substrate, e.g. polymeric. As such, the window feature can be readily identified, e.g. optically, and its position accurately determined. It should be noted that whilst optical recognition of the window feature is preferred, this is not essential and in other examples the window feature could be detected e.g. by measuring the texture or thickness of the fibrous substrate, since these characteristics will also change significantly in the vicinity of the window feature.
Secondly, since the window feature is formed during formation of the fibrous substrate itself (e.g. during the papermaking process), it is automatically in register with any other integral features that may be introduced during the same substrate formation process, at least locally (e.g. within the distance corresponding to at least one security document to be formed from the substrate). These may include watermarks, embedded threads or tactile features for example, as discussed further below. The security feature applied in step (c) will therefore automatically additionally be in register with any such additional integral features. Indeed, as discussed below in some embodiments it may be desirable to remove the window feature itself from the finished security document, the security-enhancing registration being between the security feature applied in step (c) and a second integral feature formed in the fibrous substrate during paper making, such as a watermark. Since elements such as watermarks, embedded threads and tactile features are advantageously covert, i.e. of low visual contrast with their surroundings, at least under standard reflected illumination, it has conventionally been difficult or impossible to accurately register a further security feature such as a print with elements such as these. US-A-2009/0320660 discloses a method in which watermarks formed in a paper substrate are detected by camera and an opening is then formed (e.g. by stamping) at a location based on that of the watermark. However, since the watermark will inevitably have a low contrast against its surroundings, its position can only be detected with low accuracy and hence high registration between the watermark and the opening cannot be achieved. Moreover, in order to detect the watermark at all it is necessary to back-illuminate the paper substrate and in many circumstances this is not feasible, as in the case of applying a security feature to an assembled multi-page document such as a passport booklet. As noted above, by providing a window feature in the fibrous substrate, the presently disclosed method achieves high registration since the location of the window feature can be accurately determined, and can be flexibly deployed since it does not rely upon trans-illumination of the substrate.
As already noted, the window feature can take various forms. In many preferred embodiments, at least part of the window feature is an aperture which extends through the whole thickness of the fibrous substrate with no obstructions, such that an object or surface placed on one side of the substrate is visible from the other side through the aperture. This enables a particularly clear distinction between the window feature and its surroundings since the characteristics of the two areas are markedly different. For example, the optical density of the substrate within the aperture portion of the window feature is zero, whereas its surroundings have a substantial non-zero optical density. Similarly the thickness in the vicinity of the aperture is zero and its surroundings have a measurable non-zero thickness. As such the window region can be recognised and its position determined with high reliability and accuracy.
It should be noted that in practice the aperture may be closed at one or both ends by a cover layer such as a strip or patch, which may carry indicia or security devices such as a hologram. In such cases the cover layer acts to provide the underlying surface against which the fibrous substrate is compared to identify and locate the window region. If both ends of the aperture are covered, one cover layer should be at least semi-transparent so that the window feature is still visible from at least one side in step (b). Of course, once the location of the window feature has been determined, the window feature could be concealed on both sides or, as discussed below, could be cut off and separated from the rest of the substrate entirely.
In other embodiments, the window feature comprises an aperture through at least a portion of the thickness of the fibrous substrate, through which an insert (such as a thread or strip) incorporated within the fibrous substrate is exposed. In this case, the window feature may or may not include a portion in which an aperture extends through the full thickness to reveal objects or surfaces behind the substrate. However, the exposing of the insert provides a surface against which the characteristics of the substrate can be compared to determine the location of the window feature. Again, there is preferably a visual contrast between the insert and the surrounding substrate, such that the window feature can be identified optically, but alternative detection modes are envisaged including detecting a difference in thickness of the substrate where the insert is exposed, or detecting a difference in texture.
The provision of an insert in this way further increases the security of the document since it effectively amounts to a third security element which a counterfeiter must replicate in order to forge the document. The insert may be an elongate element such as a thread or strip, but this is not essential. The insert preferably carries one or more security devices, such as a hologram, metallic layer, negative writing, magnetic material or an optically variable device such as a moire magnifier or a colour-shifting film ("optically variable" means that the appearance of the device is different at different viewing angles). The insert may be exposed by the fibrous substrate on one side only, or on both. Thus, in some embodiments the window feature includes an aperture through the full thickness of the fibrous substrate (i.e. the fibrous material is wholly absent), through which an insert incorporated within the fibrous substrate is exposed, whereby both sides of the insert are exposed through the fibrous substrate. In other cases, the window feature comprises an aperture through only a portion of the thickness of the fibrous substrate (i.e. the fibrous material is present on one side of the insert and absent on the other), through which an insert incorporated within the fibrous substrate is exposed, whereby only one side of the insert is exposed through the fibrous substrate.
In one particularly preferred implementation, the width of the insert is less than the maximum width of the window feature such that at least one edge, preferably two opposing edges, of the insert is visible in the window feature. Arrangements of this sort, and their attendant advantages, are described in WO-A-2004/001130 . In other preferred embodiments, the width of the insert is equal to or greater than the maximum width of the window feature such that the whole area of the window feature is covered by the insert. In this case there will be no full thickness aperture through which other objects are visible. Examples of such features include certain windowed thread arrangements.
As already noted, the insert may comprise a security thread, strip or foil, and preferably has a different appearance from that of the fibrous material. For example, the insert may be of a reflective or transparent appearance. The insert may carry indicia and/or security devices such as one or more holographic images, colourshift areas, security embossings, printings, liquid crystal materials etc. Where the insert is transparent it is preferable that the fibrous material is absent on both sides of the insert in the region of the window feature such that the window feature appears transparent.
The security feature applied in step (c) may take any location on the security document (e.g. on the fibrous substrate and/or insert), but in preferred examples may be located adjacent the window feature so that their relative positions can be easily checked. It should be noted that where the security feature is applied to the fibrous substrate, it is not essential that the feature be applied directly to the fibrous substrate itself. Rather, if the substrate already carries another element (prior to the performance of step (c)), such as a foil patch or laminate cover, the security feature could be applied to that element, still in registration with the window feature. Similarly, the security feature could be applied to the insert exposed by the same window feature used for registration, or to another insert, or to the same insert but in the region of a second window feature. The security feature may also be applied to both the fibrous substrate and the insert - for example, a serial number could be printed or laser marked across both the fibrous substrate and insert.
A single window feature of the sort described above may be provided but in other preferred examples, the fibrous substrate comprises a plurality of window features, preferably being arranged along a straight line. If the substrate is later cut into multiple documents, one or more than one of the window features may ultimately be carried by each finished security document. The provision of multiple window features enables more accurate registration since the location of each can be measured and used to position the security feature applied in step (c).
As alluded to above, additional features may be formed in the fibrous substrate in addition to the window feature and in an especially preferred embodiment, the fibrous substrate provided in step (a) further comprises a second integral feature formed during formation of the fibrous substrate in register with the first integral feature, whereby the security feature applied in step (c) is registered to both the window feature and the second integral feature. As noted previously, an "integral" feature is one formed during the making of the fibrous substrate, not applied to the finished substrate material. Advantageously, the second integral feature comprises a watermark, a partially or fully embedded element, or a marking on an embedded portion of a partially or fully embedded element. Typically, the second integral feature will be covert compared to the first integral feature and preferably will be the more visible when the fibrous substrate is viewed in transmitted light than in reflected light. For example, the second integral feature may be substantially invisible in reflected light and revealed upon viewing in transmitted light.
The provision of a second integral feature to which the security feature will be registered is particularly advantageous since registration to such features and particularly watermarks has previously been difficult or impossible to achieve in view of their intentionally poor visibility under standard viewing conditions As mentioned above, the location of such features can be more accurately identified by illuminating the substrate with a back-light, but this is not feasible in all situations. By exhibiting register between a security feature and a second integral feature of this sort, the difficulty of counterfeiting is further increased and thus the security of the document enhanced.
The use of features which are substantially invisible in reflected light and revealed upon viewing in transmitted light, such as watermarks and (at least partly) embedded elements, as the second integral feature is particularly preferred since the registration between it and the security feature is not immediately apparent. The security feature appears as a standalone element under normal reflected-light illumination, but when viewed in transmission the relative positioning between the two features is revealed and can be checked. Hence the registration is effectively covert which further increases the difficultly of counterfeiting. "Watermarks" are defined here as at least one region of the fibrous substrate which is of different fibre density from that of the bulk of the fibrous substrate, and may include complex, multi-tonal images such as portraits as well as less decorative structures, such as bridge regions of a window thread arrangement and reinforcing watermarks such as those described in WO-A-03/046282 . The watermark can be positive and/or negative, including region(s) of higher and/or lower fibre density than that of the bulk substrate respectively. Watermarks can be formed using any known watermarking method including impressing a watermark pattern into the fibrous suspension on a Fourdrinier machine. However, cylinder mould watermarks watermarks are preferred since the resulting images are generally more visually distinct.
As in the case of the window feature mentioned above, the position of the second integral feature may also deviate slightly in its precise position on the substrate from the expected template position and/or from document to document. By providing detecting step (b), the position of the first integral (window) feature is accurately and precisely known. As a result, the position of the second integral feature can be considered to be known to within a tolerance that is governed by the shrinkage or distortion which occurs between the two features which are to end up on the same document. In other words, while the position of integral features may vary, for example, by ± 3 mm from document to document, the position of a second integral feature relative to a first integral feature located on the same document will vary by a much smaller margin, and in practice the degree to which the relative positions vary can generally be considered to be negligible. The present invention therefore not only provides that a security feature can be applied precisely in register with a detected window feature, but can also be applied precisely in register with a second integral feature of the substrate. Furthermore, as mentioned above, because the window feature can be made to exhibit a high visual contrast, and can therefore be detected very precisely, a security feature can be applied to the substrate more precisely in register with a second integral feature having low visual contrast than if said second integral feature itself had been detected.
Partially or fully embedded elements (such as security threads or strips) can be incorporated into the fibrous substrate by inserting the element into the fibrous material as it is deposited to form the substrate. One method of partially embedding an element is disclosed in EP-A-0059056 , which can also be used to form window features as described below. The portions of the element which are covered by the fibrous material on both sides are generally not readily perceivable when the substrate is viewed in reflected light but are visible when viewed in transmission since they are typically of greater opacity than the fibrous material, e.g. metallised. Such elements may also carry markings such as negative indicia where the opacity is reduced, which will also become visible within the substrate upon viewing in transmission.
The security feature could be provided at any location relative to the window feature (first integral feature) or a second integral feature such as a watermark. However, advantageously, the security feature is configured to visually co-operate with the first integral feature and/or with the second integral feature, if provided. That is, the security feature and the first and/or second integral feature(s) are designed such that, when viewed together, they form a recognisable combination which is easily describable and therefore allows for straightforward checking of their relative position. For example, in one particularly preferred case, the security feature may be configured to frame (e.g. surround or encircle) the first or second integral feature, preferably by following the periphery of the integral feature, e.g. along a line substantially matching the shape of the window periphery or watermark and spaced from it by a small distance. In one example, the security feature may be configured to follow the outline of a circle or other shape and, upon viewing in transmitted light, a watermark may appear within the outline, preferably centred on its centre point. In this way, the security feature and the first or second integral feature can be directly compared with one another in order to check that the required registration is present. Where the visual co-operation is arranged between the security feature and the second integral feature (e.g. watermark), it may be necessary to view the substrate in transmitted light in order to see, and therefore check for, the desired co-operation.
Alternatively, if the security feature is applied to an insert exposed in a window region (which may be the window region utilised in step (b) or not), the visual co-operation can be achieved by framing of the security feature by the window feature.
In other examples of visual co-operation, the security feature may be located immediately adjacent, abutting or partially overlapping the first or second integral feature such that when both are visible they together form a recognisable feature in combination. For example, in one preferred embodiment, the security feature is configured to represent a first, incomplete, portion of an indicia and the first or second integral feature is configured to represent a second portion of the same indicia such that when viewed in combination, the complete indicia is visible. For instance, a watermark could provide one half of a letter, number or symbol and the security feature could provide the other half. Similarly, a watermark could denote a currency symbol, such as "£" or "$", and the security feature could exhibit the denomination of a document, such as "5" or "10", such that together the currency symbol and denomination are visible alongside one another and in correct alignment, e.g. "£5".
In another example of visual co-operation, the security feature may be configured to overlap and align with the second integral feature. For example, the security feature could comprise a print which is configured to "colour in" the second integral feature, e.g. a watermark or embedded thread. Any misalignment between the two will be apparent when the substrate is viewed in transmission.
Where multiple window features are provided, the security feature could for example be positioned to extend between one window feature and another, or to sit at a position equidistant between two windows, or intertwine around several windows, in order to demonstrate the level of registration achieved.
Typically, the fibrous substrate itself and any features integral to the substrate, such as the window feature, will be manufactured in a separate process and often by a separate entity, from that including steps (b) and (c). For example, the fibrous substrate may be made at a paper-making facility and then supplied to a document manufacturing line, e.g. a printing press or a document personalisation machine, for the performance of the disclosed method. Nonetheless, in some preferred embodiments, the method may further comprise, before step (a):

(i) forming the fibrous substrate and the window feature.

EP-A-0059056

WO-A-93/08327

The particular method selected will depend upon the desired structure of the window feature. In some preferred implementations, in step (a) the window feature is formed by providing a drainage restriction area on the porous support whereby the deposition of fibres in the region of the drainage restriction area is reduced or inhibited. The drainage restriction area(s) may be formed by affixing a material such as metal, wax or polymer to the porous support at the desired locations. Examples of such techniques are disclosed in more detail in WO-A-2004/001130 . Methods utilising a drainage restriction area are particularly well suited to the formation of window features comprising apertures through the full thickness of the substrate.
Such techniques can also be adapted to incorporate an insert within the fibrous substrate exposed on one or both sides, in which case step (i) preferably comprises: (i1) depositing fibres onto the porous support surface around the drainage restriction area to form a first layer; (i2) bringing an insert to lie in contact with the drainage restriction area; and (i3) depositing further fibres over the first layer to form a second layer which securely embeds at least a portion of the insert within the fibrous substrate at least outside the drainage restriction area; whereby an aperture is formed at least through the first layer of the fibrous substrate and optionally also through the second layer. The extent of the aperture through the substrate is determined by the nature of the drainage restriction area: in some embodiments, the drainage restriction areas are adapted so as to substantially prevent the deposition of fibres thereon before and after the insert is laid thereover, whereby both sides of the insert are exposed through the fibrous substrate. This may be achieved for example by making the drainage restriction area sufficiently wide to prevent fibres bridging it and/or by making the area substantially impervious to the fluid carrying the fibres, e.g. through the use of a polymer resin, or metal or ceramic body. In other embodiments, the drainage restriction areas could be adapted so as to allow the deposition of fibres thereon after the insert is laid thereover, whereby only one side of the insert is exposed through the fibrous substrate. This could be achieved for example by arranging the drainage restriction area to be narrow enough that it can be bridged by some fibres and/or by providing it with some permeability to the fluid, but reduced compared to the main part of the porous support, e.g. through the use of a perforated metal or polymer member.
However, if only one side of the insert is to be exposed it is generally preferred to utilise alternative manufacturing techniques such as those disclosed in EP-A-059056 . In such cases, step (i) comprises forming the window feature by: (i1') providing a raised area of the porous support surface; (i2') bringing an insert to lie in contact with the raised area; and (i3') depositing fibres onto the porous support surface in such a manner that substantially no fibres are deposited between the raised area and the insert, whereby the insert becomes generally disposed within the thickness of the sheet formed by the deposited fibres away from the raised area, such that the insert is exposed through an aperture in the layer on one side.
Where a second integral feature such as a watermark or embedded element is provided, step (i) further comprises, during formation of the fibrous substrate, forming the second integral feature in the fibrous substrate. This can be achieved using any appropriate technique such as watermarking or incorporation of a thread.
In some implementations, the fibrous substrate provided in step (a) may be substantially unprocessed (e.g. unprinted), and the disclosed method may form a core part of the production of security documents from the substrate. For example, in comparative examples, the substrate may be provided as a continuous web or sheet from which individual security documents are cut after performing steps (b) and (c). However in accordance with the invention, step (a) comprises providing a substantially complete security document, referred to as a precursor security document, which comprises the fibrous substrate and has already undergone a number of manufacturing steps. For example, the precursor document may only require personalisation in order to produce the finished security document. In particular, the precursor security document comprises a plurality of joined pages, at least one of the pages comprising the fibrous substrate. For example, the precursor security document could be a booklet such as a blank passport booklet which is substantially complete save for application of data relating to its intended holder (i.e. personalisation of the document). If the method includes the manufacture of the precursor security document (step (ii)), this is performed before step (a) (but after step (i), if this forms part of the method).
The location of the window feature can be detected in step (b) by various different means, including via measurements of the thickness of the substrate, its texture or other characteristics. However, it is preferred to locate the window feature using optical recognition techniques and hence step (b) advantageously comprises:

(b1) capturing an image of at least a portion of the fibrous substrate including at least part, preferably all, of the window feature, using an image capture device;
(b2) processing the captured image to recognise the window feature and identify its location within the captured image; and
(b3) calculating the offset between the identified location of the window feature and a predetermined template location of the window feature.

Step (b2) can be implemented for example, by performing known feature extraction and/or pattern recognition routines on the captured image.
Further preferably, step (c) comprises:

(c1) calculating an application position for the security feature based on the offset calculated in step (b3) and a predetermined template location of the security feature; and
(c2) applying the security feature to the fibrous substrate and/or insert at the calculated application position.

The process may be carried out by a processor receiving input from the image capture device, such as a camera or video camera, which then controls the operation of, or provides input to, an application module such as a printer for applying the security feature in step (c). A template defining the desired location of at least the security feature relative to the window feature, and preferably also any watermark provided on the document, is stored in memory. Having determined the offset (i.e. discrepancy) between the desired location of the window feature on the substrate and the actual detected location in step (b3), the result is used to adjust the position at which the security feature is applied to the substrate by the same amount and direction, so that the final positioning between the two features resembles that defined in the template.
The security feature applied in step (c) can take any form and may for example be applied to the security document by one or more of: printing, perforation, laser marking, laser perforation, laser engraving, inkjet personalisation, xerography, a transfer process, stamping or embossing, or any combination thereof. In preferred examples, the security feature may comprise any of:

a marking, preferably taking the form of one or more characters such as alphanumerical text or numbers, symbols, logos, graphics or photographic images;
an optically variable region, preferably comprising an optically variable ink based on any of: liquid crystal pigments, interference pigments, optically variable magnetic interference pigments and optically variable pigments based on photonic crystal materials;
micro-text;
a diffractive element, preferably a hologram or kinegram; or
a tactile relief structure.

In particularly preferred examples, the security feature may contain individualisation data unique to the document, such as personalisation data related to an owner of the document, or a serial number. For example, in a passport the security feature could comprise a marking, optionally microtext, exhibiting the passport holder's name and/or date of birth. The marking could be formed by printing or laser inscription for example.
Thus in preferred embodiments, the method further comprises:

reading an identifier carried by the fibrous substrate; and
retrieving a corresponding data record from a database, based on the identifier;
wherein the security feature applied in step (c) is configured in accordance with the retrieved data record and preferably comprises at least some of the data contained in the record.

The database may be local to the apparatus or remote and may form part of the presently disclosed apparatus. The identifier could be a serial number or other code which can be read optically from the substrate, optionally by the same detector module as that used to detect the location of the window feature. Alternatively the identifier could be read from an RFID chip or similar carried by the document. It should be noted that the identifier does not need to be disposed directly on the fibrous substrate but could be otherwise attached thereto. For example, in a multipage document, the identifier could be located on a different page to that formed by the fibrous substrate having the window feature. The security feature preferably contains personalisation information relating for example to the owner of the document, but this is not essential. For example, the security feature may be selected from a set of pre-determined options based on the retrieved data, e.g. the security feature may comprise a representation of a national flag selected according to the nationality of the owner.
The security feature may or may not be visible to the human eye under standard illumination conditions, and could comprise any of:

a luminescent, fluorescent or phosphorescent substance;
a magnetic and/or electrically conductive substance;
a photochromic substance; or
an optically variable amplitude interference substance.

The provision of such substances further increases the security level of the document. For instance, the presence of the security element may only be revealed by illumination at a non-visible wavelength such as UV. The security element could be observable both by a human viewer and by machine, or by machine only (e.g. if formed of a substance which emits/reflects outside the visible spectrum only).
Preferably, steps (b) and (c) are performed in an in-line process, i.e. without physical interruption, in order to achieve good registration. As indicated above the formation of the fibrous substrate typically cannot be carried out in the same in-line process since different equipment is required, and the substrate must be dried before steps (b) and (c) can be performed. In some preferred embodiments, the method is a web-based continuous production method, i.e. an elongate web of the fibrous substrate is provided and carries a series of the window features, the locations of which are detected and offsets calculated to provide input to a printing press or other application module which applies the security features continuously or at least repeatedly along the web. The web is then cut into individual security documents. However, the disclosed method is particularly well adapted for use as an individual or batch-fed document production method, where the documents are processed one-by-one. For example, the method may form part of a document personalisation process in which steps (b) and (c) are used to apply a security feature relating to the owner of the document to an otherwise near-complete precursor document comprising the substrate, provided in step (a).
In some embodiments, the method advantageously further comprises applying a polymeric coating to one or both sides of the fibrous substrate, before or after steps (b) and/or (c), preferably by printing, extrusion or lamination with or without an adhesive. This may be provided to act as a protective cover for the window feature and/or the security feature or other features on the substrate and may extend over all or only part of the substrate. Preferably the coating is transparent or semi-transparent, although the coating may itself carry one or more security devices. For example the coating may comprise a polymeric film exhibiting a hologram or other diffractive device.
As noted at the outset, once the window feature has been used to position the security feature, its presence is no longer essential and hence it may be omitted from the finished security document. Hence in some embodiments the method further comprises cutting the fibrous substrate to remove the first integral feature whereby the second integral feature and security feature are retained on the security document. However in many cases the window feature itself provides an indication of authenticity and so will be retained on the document.
A comparative security document is disclosed comprising:

a fibrous substrate;
a first integral feature comprising a window feature formed during formation of the fibrous substrate and/or a second integral feature formed during formation of the fibrous substrate, wherein the window feature, if provided, comprises an aperture through at least a portion of the thickness of the fibrous substrate, through which an insert incorporated within the fibrous substrate is exposed, and/or an aperture through the full thickness of the fibrous substrate; and
a security feature applied to the substrate and/or insert in registration with the window feature and/or second integral feature;
the security document being manufactured in accordance with the method described above.

As already indicated, the finished security document may comprise either the window feature or a second integral feature such as a watermark feature, or both. The security feature will be registered to whichever of these features is provided, i.e. both, if both are present.
A comparative security document is disclosed, comprising:

a fibrous substrate;
a first integral feature comprising a window feature formed during formation of the fibrous substrate and/or a second integral feature formed during formation of the fibrous substrate, wherein the window feature, if provided, comprises an aperture through at least a portion of the thickness of the fibrous substrate, through which an insert incorporated within the fibrous substrate is exposed, and/or an aperture through the full thickness of the fibrous substrate; and
a security feature applied to the substrate and/or insert in registration with the window feature and/or second integral feature;
the security feature being configured to visually co-operate with the window feature and/or the second integral feature.

As discussed above, this configuration is particularly beneficial since the registration between the window feature and the security feature or between the second integral feature and the security feature can be readily checked. Preferably, the security document is formed using the method already described.
A comparative security document is disclosed, comprising a plurality of pages joined to one another, wherein at least one of the pages comprises:

a fibrous substrate;
a first integral feature comprising a window feature formed during formation of the fibrous substrate and/or a second integral feature formed during formation of the fibrous substrate, wherein the window feature, if provided, comprises an aperture through at least a portion of the thickness of the fibrous substrate, through which an insert incorporated within the fibrous substrate is exposed, and/or an aperture through the full thickness of the fibrous substrate; and
a security feature applied to the substrate and/or insert in registration with the window feature and/or second integral feature.

As discussed above, conventional registration techniques have relied upon the use of trans-illumination to approximately locate features such as watermarks, which is not feasible in the case of multi-page documents. Using the presently disclosed techniques, multi-page documents can be configured to include a security feature registered to one or more integral features formed in the fibrous substrate which as described above enhances the security level of the document. This is of particular benefit where the security feature is related to the owner of the document, e.g. containing personalisation information, in which case it will vary from one document to the next. The presently disclosed methods enable a security feature containing such information to be applied individually to each document once its physical, multi-page construction is substantially complete, whilst still being registered to an integral feature of the substrate. This allows a stock of "blank" precursor documents (e.g. booklets) to be manufactured and then, in a separate process, personalised on-demand to add the registered security feature. Conventional documents of this sort have not exhibited register between personalised features and integral features of the substrate.
In any of the security documents described above, if a second integral feature is included, the second integral feature preferably comprises a watermark, a partially or fully embedded element, or a marking on an embedded portion of a partially or fully embedded element. As previously noted, the window feature need not be present in the finished document, but this is preferred.
The security feature is preferably configured to visually co-operate with the window feature and/or the second integral feature, for example by arranging the features according to any of the configurations described previously.
A plurality of comparative security documents are disclosed, each in accordance with one of the definitions set out above, wherein the security feature has substantially the same position relative to the window feature and/or to the second integral feature in each of the plurality of documents. In preferred examples, the security feature on each respective security document differs from the security features on the other security documents, preferably exhibiting individualisation data pertaining to an owner of the respective security document. The security documents may otherwise be substantially identical to one another (aside from any additional personalisation data applied in addition to the security feature).
A comparative apparatus for manufacturing security documents is disclosed, comprising:

a transport assembly adapted to convey a fibrous substrate along a transport path, the fibrous substrate comprising a window feature formed during the formation of the fibrous substrate, the window feature comprising: an aperture through at least a portion of the thickness of the fibrous substrate, through which an insert incorporated within the fibrous substrate is exposed, and/or an aperture through the full thickness of the fibrous substrate;
a detector module adapted to detect the location of the window feature on the fibrous substrate;
a processor adapted to calculate a position on the fibrous substrate and/or on the insert referenced to the detected location of the window feature; and
an application module adapted to apply a security feature to the fibrous substrate and/or the insert at the calculated position, such that the security feature and the window feature are registered to one another.

Advantageously, the detector module comprises an optical image capture device, preferably a camera or video camera. However alternative means such as a document thickness detection assembly could be used. The application module could take any form appropriate for manufacturing the selected security feature but preferably comprises (one or more of) a printing module, perforation module, laser marking module, laser perforation module, a transfer module, a stamping module, a document numbering module, a personalisation technology module or an embossing module. Preferably, the apparatus is adapted to perform the method described above. Hence the processor preferably stores and executes the method steps necessary to implement steps (b) and (c), including steps (b1) to (b3) and (c1) to (c2) if utilised.
The same security feature could be applied to each of a series of documents. However in particularly preferred implementations the security feature may be specific to each document, e.g. containing personalisation information relating to the document's owner. Hence, preferably, the fibrous substrate carries an identifier and the processor is further adapted to read the identifier carried by the fibrous substrate, and to configure the security feature applied by the application module in accordance with the retrieved data record, the security feature preferably comprising at least some of the data contained in the record. The database may be local to the apparatus or remote and may form part of the presently disclosed apparatus. The identifier could be a serial number or other code which can be read optically from the substrate, optionally by the same detector module as that used to detect the location of the window feature. Alternatively the identifier could be read from an RFID chip or similar carried by the document.
In implementations, the transport assembly is adapted to convey precursor security documents comprising the fibrous substrate one by one along the transport path, wherein the precursor security documents each comprise a plurality of joined pages.
Examples of security documents, methods of manufacture and corresponding apparatus for manufacture in accordance with the present invention will now be described with reference to the accompanying drawings, in which:

Figure 1 shows a flow chart illustrating a method for manufacturing a security document according to a first embodiment of the present invention;
Figures 2(a) and 2(b) show an exemplary security document according to the first embodiment of the present invention, in plan view and cross-sectional view respectively;
Figure 3 shows an exemplary apparatus for manufacture of a security document according to the first embodiment of the present invention;
Figure 4 shows a flow chart illustrating a method for manufacturing a security document according to a second embodiment of the present invention;
Figure 5 shows an apparatus for forming a fibrous substrate suitable for use in the method of Figure 4;
Figures 6(a) and 6(b) show an exemplary security document according to the second embodiment of the present invention, in plan view and cross-sectional view respectively;
Figure 7 shows an exemplary security document according to a third embodiment, which can be manufactured by the method of the present invention.
Figure 8 shows a flow chart illustrating a method for manufacturing a security document according to a fourth embodiment of the present invention;
Figure 9 shows an exemplary security document according to a comparative example;
Figure 10 shows an apparatus for forming a fibrous substrate suitable for use in producing the security document of the comparative example.
Figure 11 shows an apparatus for manufacture of a security document according to the comparative example;
Figure 12 shows part of an exemplary security document according to a further comparative example;
Figure 13 shows part of an exemplary security document according to a further comparative example;
Figure 14 shows part of an exemplary security document according to a further comparative example;
Figure 15 depicts a sheet article including a further comparative example of a security document;
Figures 16(a), 16(b) and 16(c) show an exemplary security document according to a fifth embodiment, which can be manufactured by the method of the present invention in plan view, a first cross-sectional view and a second cross-sectional view respectively; and
Figure 17 shows an exemplary security document according to a sixth embodiment, which can be manufactured by the method of the present invention.

Figure 1 shows a flow chart illustrating a method for manufacturing a security document according to a first embodiment of the present invention, and an example of a security document 1 formed using the process is shown in Figures 2(a) and 2(b). In this example the document 1 is a passport and at least one of its pages, preferably data page 2a, is formed using the disclosed method. Figure 3 shows an exemplary apparatus adapted to form the security document 1 of Figure 2(a) by the process illustrated in Figure 1.
The method includes a first step S100 of providing a fibrous substrate 2, such as paper, formed by deposition of fibres onto a porous support, as is generally known in the art. The fibrous substrate may comprise any fibrous material, such as paper or card, formed by a fibre deposition process. For example, the substrate could be formed using a round screen deposition cylinder machine or a Fourdrinier machine.
The fibrous substrate 2 comprises at least one first integral feature, which in this case is a window feature 3, formed during the deposition process. In this example, the window feature formed during the deposition process is an aperture through the full thickness of the fibrous substrate 2 as shown in Figure 2(b). This form of window feature 3 is advantageous because the fibrous substrate 2 can be arranged against a suitable background, as seen through the aperture, such that the aperture provides an area of high visual contrast in comparison to the body of the paper. The passport cover 8, shown in Figure 2(b), could be used for this purpose where the process is to be performed on a precursor security document such as this assembled passport booklet. However in other cases the substrate may be processed before forming into a booklet and in this case a suitable reference surface, or simply a gap, can be arranged to provide contrast. Furthermore, apertures formed during the formation of the fibrous substrate are readily distinguishable from window features added after the paper making process has been completed, as might be the case in counterfeit documents. For instance, an aperture formed during papermaking will typically display irregular edges 3a at which fibres may be visible. In other examples, the window feature 3 may comprise an aperture through all or a part of the fibrous substrate thickness 2, wherein an insert, such as a thread, incorporated within the fibrous substrate is exposed by the aperture, and examples of this approach will be given below. Window features which incorporate an insert are particularly advantageous as they can also be configured to provide an area of high visual contrast and, further, the requirement for an insert represents an additional obstacle in attempts to counterfeit the security document.
The fibrous substrate 2 may be provided to an apparatus 200, of which an example is shown in Figure 3, in the form of a precursor security document, such as an assembled passport booklet 1, for processing in accordance with the subsequent method steps. The apparatus 200 may comprise for example a document processing apparatus such as that disclosed in WO-A-2009/037414 . In this example the apparatus 200 receives the passport booklet 1 via an input hopper 205 and opens the booklet to data page 2a.
The method then includes step S200 of detecting the location of the first integral feature on the fibrous substrate 2. According to a first embodiment of the present invention, the first integral feature is the window feature 3, and the location of the window feature on the fibrous substrate may be determined by a detector module 201, as seen in Figure 3. Preferably, the detector module comprises an image sensor, such as a camera system, which captures an optical image of the fibrous substrate 2, which in this case preferably includes at least data page 2a and optionally the facing page 2b. This image is sent to a processor 202 which then identifies and calculates the location of the window feature 3 on the substrate. Due to the high visual contrast between the fibrous substrate 2 and the passport cover 8 visible through the aperture 3, the processor 202 is able to accurately identify the window feature 3 and calculate its location on the page 2a. Depending on the nature of the window feature, its location could be determined in various different ways. For example, in the present embodiment the window feature 3 is substantially circular and hence the process may involve calculating the centre of the circle defined by the window, the positioning of the security feature 5 then being performed relative to this calculated centre location. In other examples, an edge, corner or other feature of the window could be located instead.
While this example uses an image sensor 201 to identify and determine the location of the window feature 3, any detection means capable of identifying the window feature may also be used. For example, the detection means may identify the location of the window feature by measuring the thickness of the substrate 2 using for instance a sheet thickness detection apparatus as disclosed in WO-A-2011/039494 .
The next step S300 includes the application of a security feature 5 to the fibrous substrate 2. Using the location of the window feature determined in step S200 for reference, a security feature is applied to the fibrous substrate such that the security feature and the first integral feature, such as window feature 3, are registered to one another. In this example, the security feature 5 is a print, applied by a printer 301, as seen in Figure 3. The printer 301 of Figure 3 may function using any suitable printing technique such as laser marking, xerographic printing or thermal printing. The location data calculated by the processor is used to adjust the positioning of the print on the security document such that the security feature 5 is printed in register with the window feature 3.
The security feature 5 applied by the print device could take any form such as patterns, symbols, images or logos. The same types of markings could alternatively be formed by other means such as laser marking, perforation or embossing. In other examples the security feature could comprise a device, such as a hologram, kinegram or foil, applied for example by a transfer method such as hot stamping. The security feature applied by the print device 301 in the present example comprises microtext, as seen in Figure 2(a), which is of such small dimensions that it may not be legible to the naked eye under standard viewing conditions, but is readable under magnification and/or close inspection. Advantageously, the microtext may be configured such that the text includes personalisation information, such as the name, nationality and/or date of birth of the passport holder, thereby enabling simultaneous checking that the security feature 5 is associated correctly with both the window feature 3 and the personalisation data 7b. In this example, the microtext 5 is printed adjacent to the window feature 3; however other examples will be described below in which the security feature 5 visibly cooperates with the window feature 3.
The fibrous substrate could additionally comprise one or more second integral features, such as a watermark or embedded thread, as discussed below. Other features such as bands of fibres or planchettes could also be inserted into the fibrous substrate.
The security feature 5 may comprise additional features such as a luminescent, fluorescent or phosphorescent substance, a magnetic and/or electrically conductive substance, a photochromic substance, and/or an optically variable amplitude interference substance such as interference pigments or liquid crystal pigments. The inclusion of such additional features is particularly advantageous as they serve as additional obstacles in attempts to counterfeit the security document.
The method described above is compatible with many additional features and processes associated with passport production. For instance, the security document 1 can be manufactured to include other features typically present in a passport such as a passport photograph 7a, personalisation data headings 7b(i), personalisation data 7b(ii) and a machine readable zone (MRZ) 7c, each of which are typically printed on data page 2a. Further, any of the printed features 7a, 7b(i), 7b(ii), 7c may be applied in the same step in which the security feature 5 is applied and/or by the same printer 301 that prints the security feature, but this is not essential. These printed features 7a, 7b(i), 7b(ii), 7c may be registered to the window feature 3 or to other features of the page. For example, the MRZ 7c may be applied in register with an edge of the page 2a, and the detector module 201, processor 202 and printer 301 may be calibrated to perform this function as well by optically detecting the location of the page edge and positioning the MRZ accordingly. The personalisation data headings 7b(i) may be pre-printed on the page 2a prior to the passport booklet 1 being provided to the apparatus 200. Steps S200 and S300 may therefore also include the process of printing the personalisation data 7b(ii) in register with personalisation data headings 7b(i) already on the page, by optically detecting the headings 7b(i). This process may be performed in whole or in part by any of the detector module 201, processor 202 and printer 301 of apparatus 200.
The method may additionally include the step of applying a polymeric coating 7d, such as a laminate film, to one or both sides of the fibrous substrate 2 either before or after steps S200 and/or S300. In the case of a passport it is preferable to apply a laminate patch 7d over the data page 2a once all of the printed features 5, 7a, 7b(i), 7b(ii) and 7c have been applied. The laminate 7d is at least semi-transparent and may include security devices such as a hologram. In the present example, the apparatus 200 includes a lamination module 500 which applies the laminate patch to data page 2a after printing is complete.
The passport may also include additional security elements such as a microprocessor or RFID chip 9 and a laser perforated serial number 10. Typically the laser perforated serial number 10 will be applied to the passport booklet before it is supplied to apparatus 200, in order that each blank passport can be identified and tracked. The RFID chip 9 may be programmed separately but in the present example, apparatus 200 includes a RFID writing module 401 which can be used to write data, such as bibliographic and/or biometric data of the passport holder, into the chip.
In particularly preferred embodiments, the apparatus 200 references a database 203 to retrieve the personalisation data to be applied to each passport. The database may be local to the apparatus or could be accessed remotely across an appropriate communications network such as a local area network or the internet. In such embodiments, camera 201, or a separate detector device, takes an image of the laser perforated serial number 10, or an alternative unique identifier, already present in the passport booklet when it is supplied to the apparatus 200. The processor 202 performs an optical recognition process to identify the serial number, and the database is referenced to retrieve the personalisation data associated with said serial number. Once the personalisation data is retrieved, the printed personalisation data 7b(ii) may be applied to the passport as described above. Furthermore, the security feature 5 may be configured based on the information retrieved from the database 203. For example, the security feature 5 may include all or part of the personalisation data, for example the microtext may include print indicating the name or date of birth of the passport holder. However the security feature 5 need not be unique to the passport holder but could for instance be selected from a finite number of options based on the retrieved information. For example, the security feature could indicate the nationality of the holder, e.g. via text or an image of the relevant national flag, based on the corresponding information in the retrieved database record.
Figure 4 shows a flow chart illustrating an exemplary process for manufacturing a fibrous substrate 2 suitable for use in the subsequent method steps S200, S300, e.g. forming the data page 2a described above. The illustrated process includes steps for producing a fibrous substrate including a window feature 3 either with or without an insert, as detailed below. Figure 5 shows an example of an apparatus for production of the fibrous substrate 2 by the method outlined in Figure 4. Figures 6(a) and 6(b) show a second exemplary security document 11 which again is a passport and at least one of its pages, preferably data page 12a, comprises a fibrous substrate 12 formed using the method of Figure 4.
The exemplary substrate manufacturing process includes a first step S101 of depositing fibres from a fibrous stock 111 onto a porous support surface 110 around a drainage restriction area 113. In this example the fibre deposition process uses a cylindrical porous support surface 110, shown in Figure 5. The porous support surface is rotated through a vat of fibrous stock 111 and fibres from the fibrous stock begin to deposit on porous support surface forming a fibrous substrate build-up 112. The porous support surface 110 includes at least one drainage restriction area 113 for production of a window feature 3. The drainage restriction area acts to retard the deposition of fibres, either wholly or in part, as it is rotated through the fibrous stock 111 in order to form either a full or partial thickness window feature 3 in the fibrous substrate build-up 112. Optionally, additional drainage restriction areas 113 may be provided to partially restrict the fibre deposition and form watermark features. Watermark features will be discussed in greater detail below.
For production of a fibrous substrate 12 with an insert 14, the method then includes the step S102 of bringing the insert to lie in contact with the drainage restriction areas 113. In this example the insert 14 is a security thread however other inserts such as strips could be introduced in the same way. As the cylindrical porous support surface is rotated through the fibrous stock 111, the security thread is brought into contact with the drainage restriction area 113. This is done below the surface so that a fibrous substrate build-up 112 has already accumulated on the porous support 110. A window feature 13 with an insert may be formed such at least one, preferably both, edges of the insert 14 are visible within the window feature, as in the example shown in Figure 6(a). This may be achieved using an insert which is narrower than the maximum width of the drainage restriction area 113 with which it is brought into contact. Alternatively, the insert may extend across the whole area of the window feature, an example of which will be provided below. This may be achieved by using an insert 14 which is at least as wide as the maximum width of the drainage restriction area 113.
The method then includes the step S103 of depositing further fibres to securely embed the insert 14. In this example, after the security thread 14 is placed in contact with the drainage restriction area 113, rotation of the cylinder continues and therefore the fibrous deposition continues, thereby embedding the security thread 14 within the fibrous substrate build-up 112, at least outside the window region 13. The drainage restriction areas 113 may be formed to prevent the deposition of fibres thereon after the insert 14 is laid thereover, resulting in both sides of the insert being exposed within a full-thickness aperture through the fibrous substrate build-up 112, as shown in Figure 6(b). Inserts disposed within full-thickness apertures are advantageous since the insert is visible from both sides of the document. Alternatively, the method may be configured to form a partial thickness aperture through which the insert is only visible from one side of the fibrous substrate. This can be achieved using the Figure 5 apparatus with appropriate adjustments to the drainage restriction areas 113. However, a more preferred alternative apparatus for forming such partial thickness apertures will be discussed in detail below.
Figure 6(a) shows an exemplary security document 11 containing a window feature 13 with an insert 14, as may be produced using the above method. In this example, the security document 11 is again a passport and the first integral feature is a window feature 13, which in this case is a porthole-type device as disclosed in WO-A-2004/001130 . With reference to Figure 3, detector module 201 takes an image of the substrate forming the data page 12a. Processor 202 then identifies the window feature 13 within the image. Advantageously, even for apertures which do not extend through the full thickness of the substrate, the insert 14 provides an area of high visual contrast allowing the processor 202 to accurately identify the window feature 13 and calculate its location on the page 12a before applying the security feature 15 in register. As in previous embodiments any characteristic point or points identifiable from the window feature can be used to define its location. For instance, in this case the two extremities of the visible portion of the insert 14 may be detected and a point mid-way between them defined as the centre point of the window feature.
In this example, the security feature 15 comprises microtext printed to form one or more concentric circles arranged around the periphery of the porthole 13 and sharing its centre point. This visual cooperation between the window feature 13 and the security feature 15 demonstrates the high register achieved and this enables a viewer to check straightforwardly that they are accurately registered to one another.
In the exemplary security document shown in Figure 6, the insert 14 present within the window feature 13 is a security thread; however, other types of insert may be used such as security strip or foil. It is preferable for the insert 14 to have a visual appearance substantially different from that of the surrounding substrate 12, thereby providing an area of high visual contrast. This may be achieved by using an insert having colour different to that of the surrounding substrate or by using an insert which is either reflective or transparent for example. In embodiments where the insert 14 is transparent, it is preferable that the window feature 13 is a full-thickness aperture such that a reference surface, such as passport cover 18, can be seen through the window. In embodiments in which the insert is reflective, identifying the location of the window feature may rely on the high visual contrast provided by the reflective insert, or alternatively on the different levels of specular reflection achieved by the insert as compared with its surroundings. Furthermore, the insert may carry indicia such as metallised or demetallised characters or symbols and/or security devices such as one or more holographic images, colourshift areas, security embossings, printings, liquid crystal materials etc. thereby providing an additional obstacle in attempts to counterfeit the security document.
In the embodiments described so far, the security feature applied in register with the window feature is printed or otherwise applied onto the fibrous substrate. However this is not essential since the substrate may carry other items to which the security feature can be applied, such as the insert mentioned already or the laminate patch. Thus, Figure 7 shows a third embodiment of a security document 21 containing a first integral feature in the form of a window feature 23 with an insert 24, which again can be produced using the above method. In this example, the security document is a passport and the window feature is, again, a porthole-type device. During the manufacture of this exemplary document, step S300 includes applying the security feature 25 onto the insert 24 where it is revealed within the window. In this example, the security feature 25 comprises microtext printed directly onto the insert 24. However, the security feature 25 could again take any of the forms previously described. For example, the insert 24 may comprise a metallised film and the security feature 25 could be formed by demetallising selected regions of the film, e.g. to form negative indicia. This may be performed by laser ablation for example. In this way, the insert can if desired be personalised to the passport holder in a manner which is extremely difficult or impossible to achieve during manufacture of the insert itself.
Figure 8 shows a flow chart illustrating an exemplary process for detecting a first integral feature, i.e. a window feature, and applying a security feature in register which may be carried out in any of the above embodiments. This process includes the step S201 of capturing an image of the window feature. With reference to Figures 2 and 3, an image is taken by detector module 201 of at least a portion of the fibrous substrate 2 such that the window feature 3 is located, at least in part, preferably wholly, within the image. Next, in step S202, the captured image is processed by processor 202 to recognise the window feature 3 and identify its location within the captured image. This may be achieved using any suitable optical recognition technique. A template defining the predetermined desired location of the security feature relative to the window feature is stored in memory and accessed by the processor 202. The template may also define desired locations of other items to be applied to the substrate, such as personalisation data items 7b(ii), relative to the same window feature or to other locations of the substrate such as its edge. Then, in step S203 an offset between the identified location of the window feature 3 and a predetermined template location of the window feature is calculated by processor 202. Step S301 then includes calculating the application position for the security feature 5 based on the offset calculated in step S203 and a predetermined template location of the security feature. In step S302 the security feature 5 is applied at the calculated application position by printer 301 resulting in a security feature registered to the window feature 3, their relative positions being in accordance with the template.
Figures 9, 12, 13, 14, 16 and 17 show further examples of security documents made in accordance with the presently disclosed techniques. Figure 10 shows an apparatus for forming a fibrous substrate suitable for use in producing the security document of Figure 9. Figure 11 shows a further comparative exampleof an apparatus for producing a security document, such as the bank notes shown in Figures 9 and 12 to 14.
The bank note 31 of Figure 9 comprises a fibrous substrate 32 wherein the first integral feature comprises a plurality of window features 33a, 33b, 33c..., arranged along a straight line, at which an insert in the form of a security thread 34 is exposed on one side of the note at each of. Suitable techniques for forming paper with windowed thread inserts of this sort are disclosed in EP-A-0059056 and WO-A-93/08327 for example. Figure 10 shows an exemplary apparatus for forming such a fibrous substrate. In this example, a cylindrical porous support surface 120 with plurality of raised porous support areas 123 is rotated through a vat of fibrous stock 121. A security thread 124 is brought into contact with the raised porous support areas 123 at a point above the surface of the fibrous stock 121. As the porous support surface 120 is rotated through the fibrous stock 121, fibres begin to deposit on the porous support surface forming a fibrous substrate build-up 122. In the areas away from the raised porous support areas 123 the fibrous substrate build-up envelops the security thread 124 on either side. In the regions of the raised porous support areas 123, the contact between the security thread and the raised porous support area prevents fibrous substrate build-up 122 on one side of the security thread, while the still permitting fibrous substrate build-up on the opposing side of the security thread. This results in the security thread 124 being exposed on one side only, thereby forming a window feature comprising a partial thickness aperture.
In the security document of Figure 9, the security thread 34 preferably has a width equal to or greater than the maximum width of the window features 33 such that the thread covers the full extent of each window feature. The bank note includes a security feature 35 registered to the multiple window features 33a, 33b, 33c. In the manufacture of this exemplary security document using the apparatus shown in Figure 11, the detector module 211 takes an image of the substrate 32 and then the processor 212 recognises and identifies the position of at least one of the plurality of window features 33a, 33b, 33c from the image. If desired, the locations of more than one of the window feature can be identified and used in applying the security device in order to increase the accuracy of registration. Using a printer 311 or other application module, the security device 35, such as a pattern or microtext, is applied so that it follows a line which weaves between the window features 33a, 33b, 33c. This arrangement is particularly advantageous as the visual cooperation between the window features and the security device 35 is distinct and any deviation from the desired position will be readily recognisable. The registration process can be performed in accordance with Figure 8 described above.
The bank note 31 also carries a second integral feature formed during the papermaking process. In this example the second integral feature is a watermark 36 which, as known in the art, comprises one or more regions of different fibre density than that of the main body of the fibrous substrate. The watermark 36 is formed during the substrate formation process, simultaneously with the window feature(s) such that the watermark and window features are in register. Any known watermarking technique can be used for this purpose but in a preferred embodiment the watermark is formed during the papermaking process described in relation to Figure 10 above, by providing additional relief structures on the porous support surface and/or applying drainage restriction areas as appropriate. Preferably, the watermark 36 is substantially invisible in reflected light but may be revealed upon viewing in transmitted light.
The provision of a second integral feature such as a watermark not only represents an additional obstacle in attempts to counterfeit the security document due to the need to accurately form the watermark, but also increases the security of the document still further as a result of its combination with the aforementioned security feature 35. Since the first integral feature and the second integral feature are both formed during the fibre deposition process, they are intrinsically registered to one another. As a result, a security feature applied according to the presently disclosed method will automatically be registered to the second integral feature, as well as to the first integral feature. In this example, this results in a security feature 35 which is automatically registered to the watermark 36 of the bank note 31, as well as to the window feature(s) 33a, 33b, 33c. Therefore, during step S200 of the above method, the processor 202 may use the detected position of the window features 33a, 33b, 33c to indirectly determine the location of the watermark 36. Once the location of the watermark is determined, the security feature 35 may be applied in register with the watermark. It is therefore foreseeable that variations of the exemplary security documents discussed above may be manufactured in which the applied security feature(s) visually cooperates with either or both of the watermark 36 and the window feature(s) 33a, 33b, 33c, and examples of such are given below.
Figure 11 shows an exemplary apparatus for manufacturing a security document such as the bank note shown in Figure 9, using a continuous, web-based method. The fibrous substrate 2 including window features 33 (and optionally watermarks 36) may be provided in the form of an elongate web 102 to an apparatus 210 for processing in accordance with the subsequent method steps. In this example the fibrous substrate is provided on a roll 101 which is unwound and fed through the apparatus 210 by transport module 101a, 101b. The transport module in this example comprises rollers 101a and 101b; however, any suitable conveyor means, as generally known in the art, may be used.
The apparatus includes a camera system 211 which is used to capture an image of the window features 33 present on the elongated web 102. The processor 212 then identifies one or more of window features and determines their position on the elongate web. Using the above-described techniques, the processor determines the position at which the security feature 35 should be applied to the substrate and printer 311 then applies the desired security feature 35 onto the substrate 2 registered to the window features 33a, 33b, 33c. The elongated web 102 can then be cut into individual security documents 31 along the dashed lines indicated, using an appropriate apparatus (not shown), as is generally known in the art.
Figures 12, 13 and 14 each show part of a bank note according to three further comparative examples, formed using the disclosed method, in which a security feature is arranged to visually cooperate with a watermark. It will be appreciated that any of these configurations could equally be applied to other security documents, forming for example part of a page of a passport booklet, using techniques such as those discussed above with respect to Figures 1 to 7.
Figure 12 shows part of an exemplary bank note 41 formed of a fibrous substrate 42. The bank note carries a printed security feature 45 and a watermark 46 applied in register with one another as a result of the above process. In this example, the security feature and watermark cooperate by forming separate portions of one indicium. When viewed in reflective light, only the upper portion of the indicium, formed by the printed security feature 45, is visible. The lower portion of the indicium is provided by the watermark 46 and hence is not readily apparent. In contrast, when the bank note 41 is viewed in transmitted light, both portions are visible, and therefore the entire indicium is revealed. In this example the indicium is the digit '5' but any other character, letter, number, image, symbol, logo or pattern could be formed. This arrangement is particularly advantageous as the highly coordinated arrangement of the watermark feature 46 formed during the fibre deposition process and the security feature 45 applied subsequently poses a substantial obstacle to attempts to counterfeit the document. Furthermore, the indicium is immediately recognisable to a viewer and therefore any incorrect registration between the watermark and security feature is readily recognisable.
Figure 13 shows part of an exemplary bank note 51 formed of a fibrous substrate 52. The bank note carries a printed security feature 55 and a watermark 56. In this example, the security feature comprises printed microtext which is applied along a line which surrounds the watermark feature 56. When viewed in reflected light, only the microtext forming the perimeter of a circle is visible. When the bank note 51 is viewed in transmitted light, the watermark 56 appears in the centre of the security feature 55. This arrangement is particularly advantageous as the highly coordinated arrangement of the watermark feature 56 formed during the fibre deposition process and the security feature 55 applied subsequently poses substantial obstacle in attempts to counterfeit the document. Furthermore, a viewer is readily able to check the positioning of the security feature and watermark and can therefore recognise an incorrect registration.
Figure 14 shows part of an exemplary bank note 61 formed of a fibrous substrate 62. The bank note carries a watermark 66 formed by the process outlined above; the watermark here depicts a national flag. In this example, the watermark is a positive watermark, i.e. its regions are of greater fibre density than that of the bulk substrate. A security feature 65, in this example a coloured print, is applied over the watermark such that it provides the appropriate colours to the different areas of the national flag. When viewed in reflected light, the national flag is visible as a result of the printed colours alone. However, when viewed in transmitted light, the underlying watermark acts in combination with the print to modify the appearance of the flag. For example, the watermark may present outlines around the different coloured regions of the national flag or may result in certain coloured region of the flag appearing darker than others. Any mis-register between the print and the watermark will be readily apparent. This arrangement is particularly advantageous as it demonstrates the highly coordinated arrangement of the watermark feature 56 formed during the deposition process and the security feature 55, and for more intricate national flag designs is especially difficult to replicate in attempts at counterfeiting the document.
In some embodiments it may be desirable to provide a window feature on the substrate only for the purpose of positioning the security feature. For example, the registration of the security feature may ultimately be demonstrated relative to a watermark 36 on the fibrous substrate, as in the examples described above with reference to Figures 12, 13 and 14. In such embodiments it may be preferred to remove the window feature once the location at which the security feature is to be applied has been determined. An example of a sheet article including a security document formed in this way is shown in Figure 15. Here, the sheet 71 includes two regions 71a and 71b divided by line 71c (which may or may not be visible in practice). Region 71a corresponds to the finished security document and region 71b is an extension which will be cut off along line 71b before the document enters circulation. The window feature 73, formed during papermaking as described above, is located in the extension region 71b whilst a watermark 76 formed during the same process is located on the document region 71a. A security feature 75, which can take any of the forms mentioned in previous embodiments, is applied using the disclosed technique in register with the window feature 73 and hence automatically also in register with the watermark. The sheet article is then cut along line 71c such that only the watermark 76 and security feature 75 (and not the window feature 73) remain on the finished security document. Of course, other window features such as windowed thread 74 could still be present on the document.
Figure 16(a) shows an exemplary passport 81 according to a further embodiment, which can be manufactured by the method of the invention. In this example, the first integral feature is a window feature 83 formed by a security thread 84 exposed by a partial thickness aperture. This may be formed, for example using the method discussed above in relation to Figure 10. Figures 16(b) and 16(c) show cross-sections of the passport 81 at two points along the security thread 84. Figure 16(b) shows a cross-section of the passport across the security thread along the line B-B' in the region of the window feature 83. Figure 16(c) shows a cross-section of the passport 81 across the security thread 84 along the line C-C' at a location away from the window feature 83, where the thread is fully embedded, in the region of a security feature 85b. In this example, the second integral feature is a series of negative indicia 86a, 86b, 86c on unexposed areas of the security thread 84. Preferably these negative indicia are formed by demetalisation of the security thread. Negative indicia, such as those shown in this exemplary passport, would be substantially invisible when viewed under reflected light, but may be revealed upon viewing in transmitted light. Similarly to watermarks of previous embodiments, the negative indicia 86a, 86b, 86c are registered to the window feature 83, owing to the longitudinal accuracy with which the security thread 84 is embedded within the fibrous substrate 82 (such longitudinal registration can be achieved for example by using a method such as that disclosed in EP-A-1567714 to embed the thread 84). Therefore, the security feature 85 may be applied according to the above method such that it visually cooperates with the negative indicia, e.g. by printing. In this example, the negative indicia 86a, 86b, 86c are patterns which are outlined by the security features 85a, 85b, 85c, thereby demonstrating the highly coordinated arrangement of the negative indicia and the security feature. When viewed in reflection, only the security features 85a, 85b, 85c will be visible, each appearing as a star-shaped outline. However, when viewed in transmitted light, the negative indicia of the security thread become visible, each appearing as a solid star aligned within the star-shaped outline of the respective security feature. While matching patterns are used in this example, any combination of negative indicia and security features may be used to demonstrate the register shared by these two features. For example, the negative indicia may be text such as personalisation category headings, e.g. "name", "nationality" etc. and the security feature may be microtext applied next to the respective category heading with the corresponding personalisation data of the passport holder.
In a variant of the Figure 16 embodiment, the security feature could be configured to visually co-operate with the embedded thread 84 itself, rather than any markings carried thereon. For example, the security feature could comprise patterns or text arranged in alignment with the embedded thread, or to define the edges of the thread. This correspondence would be revealed when the page is viewed in transmitted light.
Figure 17 shows an exemplary passport 91 according to a further embodiment, which can be manufactured by the method of the invention. In this example at least the data page 92a is formed with a second integral feature in the form of reinforcing watermarks 96a, 96b in two of the corners, as known from WO-A-03/046282 . These reinforced corners comprise linear regions of higher density paper which act to protect the corners from deterioration. When viewed in reflected light, the reinforcing watermarks are substantially invisible. However, when viewed in transmitted light the higher density regions appear darker than the surrounding fibrous substrate, thereby forming a pattern in each corner. A security feature 95 may be applied such that it visually cooperates with the reinforcing watermarks 96a, 96b by using the disclosed method to identify the window feature 93 and print in register with that feature. In this example a print 95a, 95b is applied along the higher density regions of the paper in each of the corners, thereby demonstrating to a viewer the highly coordinated arrangement of the watermarks 96a, 96b and security feature.

Claims

A method of manufacturing a security document comprising a fibrous substrate, the method comprising:
(a) providing a precursor security document comprising a plurality of joined pages, at least one of the pages comprising a fibrous substrate formed by deposition of fibres onto a porous support, the fibrous substrate comprising a first integral feature formed during the formation of the fibrous substrate, the first integral feature being a window feature comprising: an aperture through at least a portion of the thickness of the fibrous substrate, through which an insert incorporated within the fibrous substrate is exposed, and/or an aperture through the full thickness of the fibrous substrate;

(b) detecting from the fibrous substrate the location of the window feature on the fibrous substrate; and

(c) applying a security feature to the fibrous substrate and/or the insert at a position referenced to the detected location of the window feature, such that the security feature and the window feature are registered to one another.
A method according to claim 1, wherein the window feature comprises either:
an aperture through the full thickness of the fibrous substrate, through which an insert incorporated within the fibrous substrate is exposed, whereby both sides of the insert are exposed through the fibrous substrate; or

an aperture through only a portion of the thickness of the fibrous substrate, through which an insert incorporated within the fibrous substrate is exposed, whereby only one side of the insert is exposed through the fibrous substrate.
A method according to any of the preceding claims, wherein the window feature comprises an aperture through at least a portion of the thickness of the fibrous substrate, through which an insert incorporated within the fibrous substrate is exposed, and wherein either:
the width of the insert is less than the maximum width of the window feature such that at least one edge, preferably two opposing edges, of the insert is visible in the window feature; or

the width of the insert is equal to or greater than the maximum width of the window feature such that the whole area of the window feature is covered by the insert.
A method according to any of the preceding claims wherein the fibrous substrate provided in step (a) further comprises a second integral feature formed during formation of the fibrous substrate in register with the first integral feature, whereby the security feature applied in step (c) is registered to both the window feature and the second integral feature.
A method according to claim 4, wherein the second integral feature comprises a watermark, a partially or fully embedded element, or a marking on an embedded portion of a partially or fully embedded element.
A method according to claim 4 or claim 5, wherein the second integral feature is more visible when the fibrous substrate is viewed in transmitted light than in reflected light.
A method according to any of the preceding claims, wherein the security feature is configured to visually co-operate with the first integral feature and/or with the second integral feature, if provided;
and preferably wherein the security feature is either:
configured to frame the first or second integral feature, preferably by following the periphery of the first or second integral feature;

configured to represent a first, incomplete, portion of an indicia and the first or second integral feature is configured to represent a second portion of the same indicia, such that when viewed in combination, the complete indicia is visible;

configured to overlap and align with the second integral feature; or

applied to an insert within a window feature, whereby the security feature is configured to be framed by the window feature.
A method according to any of the preceding claims, further comprising, before step (a):
(i) forming the fibrous substrate and the window feature.
A method according to claim 8, wherein in step (i) the window feature is formed by providing a drainage restriction area on the porous support whereby the deposition of fibres in the region of the drainage restriction area is reduced or inhibited;
and preferably wherein the window feature comprises an aperture through at least a portion of the thickness of the fibrous substrate, through which an insert incorporated within the fibrous substrate is exposed, and step (i) comprises:
(i1) depositing fibres onto the porous support surface around the drainage restriction area to form a first layer,

(i2) bringing an insert to lie in contact with the drainage restriction area,

(i3) depositing further fibres over the first layer to form a second layer which securely embeds at least a portion of the insert within the fibrous substrate at least outside the drainage restriction area,
whereby an aperture is formed at least through the first layer of the fibrous substrate and optionally also through the second layer;
and further preferably wherein the drainage restriction areas are adapted so as to substantially prevent the deposition of fibres thereon before and after the insert is laid thereover, whereby both sides of the insert are exposed through the fibrous substrate.
A method according to claim 8, wherein the window feature comprises an aperture through a portion of the thickness of the fibrous substrate, through which an insert incorporated within the fibrous substrate is exposed, and in step (i) the window feature is formed by:
(i1') providing a raised area of the porous support surface;

(i2') bringing an insert to lie in contact with the raised area; and

(i3') depositing fibres onto the porous support surface in such a manner that substantially no fibres are deposited between the raised area and the insert,
whereby the insert becomes generally disposed within the thickness of the sheet formed by the deposited fibres away from the raised area, such that the insert is exposed through an aperture in the layer on one side.
A method according to any of claims 8 to 10 when dependent on claim 4, wherein step (i) further comprises, during formation of the fibrous substrate, forming the second integral feature in the fibrous substrate.
A method according to any of the preceding claims, wherein step (b) comprises:
(b1) capturing an image of at least a portion of the fibrous substrate including at least part, preferably all, of the window feature, using an image capture device;

(b2) processing the captured image to recognise the window feature and identify its location within the captured image; and

(b3) calculating the offset between the identified location of the window feature and a predetermined template location of the window feature;
and preferably wherein step (c) comprises:
(c1) calculating an application position for the security feature based on the offset calculated in step (b3) and a predetermined template location of the security feature; and

(c2) applying the security feature to the fibrous substrate and/or the insert at the calculated application position.
A method according to any of the preceding claims, wherein in step (c) the security feature is applied to an element which has been applied to or incorporated into the fibrous substrate prior to step (c).
A method according to any of the preceding claims, further comprising:
reading an identifier carried by the fibrous substrate; and

retrieving a corresponding data record from a database, based on the identifier;

wherein the security feature applied in step (c) is configured in accordance with the retrieved data record and preferably comprises at least some of the data contained in the record.