Patent Description:
Security documents and booklets, such as passports, passbooks, identification documents, certificates, licences, cheque books and the like, commonly include a security sheet comprising a data sheet. A passport booklet typically comprises a cover, a plurality of internal visa pages and at least one data sheet displaying the personal data of the passport holder. Typically the visa pages are made from paper and are sewn together along a stitch line coincident with the fold of the document. The data sheet may be formed from a plastic, typically polycarbonate, and during its manufacture a number of thin plastic layers are laid over one another and laminated together, thereby forming a thicker plastic body. As this plastic body is typically rigid it is not directly attached at the stitch line or otherwise the booklet may not be able to bend effectively about the fold.

Instead, the security sheet may comprise a flexible hinge or attachment layer embedded in and extending from the plastic body of the data sheet and the data sheet is attached about the fold using the flexible hinge. Such arrangements are disclosed in <CIT>.

However, fraudsters may attempt to manipulate the security document by separating the data sheet and flexible hinge along the interface therebetween and replacing the data sheet with one containing fraudulent personal data.

<CIT>, entitled "Method for producing insert sheet, particularly data page, for book-like document, particularly identification document, involves connecting insert sheet with part of document by hinge element," describes the preamble of claim <NUM> or a method involving connecting ar insert sheet with a part of a document by a hinge element, particularly by seam connection. The hinge element is attached in a retainer in a main body. The retainer and the hinge element have complementary edge contours.

An object of the present disclosure includes increasing the difficulty of fraudulently dismantling a security sheet by separating a data sheet from an attachment layer. A further object of the present disclosure includes improving the identification by inspection officers of any such dismantling in a fraudulent security document. Further objects include providing an improved method of manufacture of such a security sheet and a security document comprising such a security sheet.

The present disclosure therefore provides a security sheet, security document and method in accordance the claims. In the present disclosure the term "nonlinear" means that an edge profile is not straight and comprises at least one curve and/or at least two straight lines at a non-straight angle to one another. By virtue of the inner edge profile being nonlinear a fraudster is unable to effectively separate the data sheet from the attachment layer by cutting along a straight line and parallel to an outer edge and/or fold line of the security sheet. In particular, when cutting a straight line and parallel to the outer edge and/or fold line, which is the most common and easiest method of separating the data sheet from the rest of the security sheet, they can only cut through both the attachment layer and data sheet, through only the data sheet or through only the attachment layer. As the inner edge is nonlinear, the removed data sheet will always be attached to part of the attachment layer and/or vice-versa. It is much harder for a fraudster to replace the data sheet with one containing fraudulent personal data because they will always have to replicate at least part of the data sheet and attachment layer. Due to the increased likelihood of poor replications, fraudulent alterations are therefore also easier to identify.

In the present disclosure the term "edge profile" refers to the shape or outline of an edge when an outer surface extending from the edge is viewed in plan view. Thus, for example, if a recess extends into part of the thickness of the inner edge of the data page (e.g. a hole through the centre of the thickness), the inner edge profile does not include the perimeter of the recess because the recess is not visible when an outer surface of the data sheet is viewed in plan view. However, if the inner edge includes a protrusion or recess extending across the entire thickness of the data sheet, the inner edge profile includes the protrusion or recess because they are visible in plan view. The inner edge profile may comprise at least one inner edge section. In the present disclosure the term "edge section" refers to a section or part of an edge profile and thus refers to the shape or outline of a part of an edge when an outer surface extending from the edge is viewed in plan view. The edge profile may comprise a single edge section defining the entirety of the edge profile or may be split into or defined by a plurality of edge sections adjacent to one another.

The data sheet preferably extends between the inner edge and an outer edge, which may be opposite the inner edge. The inner and outer edges may extend between parallel side edges (which may be substantially straight or linear) of the data sheet. The outer edge may comprise an outer edge profile comprising at least one outer edge section that is straight or linear. Preferably the outer edge profile is straight along at least <NUM>% of its width. The inner edge profile and/or at least one inner edge section may extend nonparallel to the outer edge, outer edge profile and/or at least one outer edge section. The present disclosure therefore provides, alternatively or in addition to the inner edge profile being nonlinear, a security sheet comprising a data sheet and an attachment layer for attaching the data sheet in a security document, wherein the data sheet extends between inner and outer edges and is attached to the attachment layer at the inner edge, the inner edge having an inner edge profile comprising at least one inner edge section extending nonparallel to the outer edge.

The attachment layer preferably comprises a fold line and the inner edge profile and/or at least one inner edge section preferably extends nonparallel to the fold line. The present disclosure also provides, in addition or alternatively to the inner edge profile being nonlinear and/or the inner edge being nonparallel to the outer edge, a security sheet comprising a data sheet and an attachment layer, wherein: the attachment layer comprises a fold line and is for attaching the data sheet in a security document; and the data sheet is attached to the attachment layer at an inner edge of the data sheet, the inner edge having an inner edge profile comprising at least one inner edge section extending nonparallel to the fold line. In the present disclosure the term "fold line" refers to a straight line of fold along which the attachment layer is designed or arranged to be folded. In particular, the attachment layer may comprise a fold (i.e. at the fold line) and/or may be folded about the fold line. The security document may comprise a stitch line for attaching the security sheet therein, such as to a cover and/or at least one leaf, although other attachment means such as adhesion may be used. The stitch line is preferably coincident with the fold line, but they may be instead be offset.

A data sheet height extending between the inner and outer edges preferably varies along a data sheet width. The data sheet width may be perpendicular to the data sheet height. In particular, by being nonlinear, the inner edge may not extend along a straight line between the two corners formed between the inner edge and the side edges. In the present disclosure "height" refers to a dimension perpendicular to the fold line and/or outer edge and "width" refers to a dimension parallel to the fold line and/or outer edge. In preferred embodiments the data sheet height may vary along the width by at least approximately <NUM>, at least approximately <NUM>, at least approximately <NUM> or at least approximately <NUM>; and/or less than or equal to approximately <NUM>, less than or equal to approximately <NUM> or less than or equal to approximately <NUM>.

The attachment layer may comprise a hinge portion located outside of the data sheet and may comprise a connection portion extending from the hinge portion into and/or onto the data sheet. The hinge portion may be formed from the part of the attachment layer that extends from the inner edge outside of or beyond the data sheet and the connection portion may be formed from the part of the attachment layer that is located in and/or over the data sheet. The connection portion may be at least partially embedded in the data sheet by extending at least partially into the thickness of the data sheet and/or may at least partially extend over at least one outer surface of the data sheet. The hinge and/or connection portion preferably extend along at least approximately <NUM>%, at least approximately <NUM>% or all of width of the inner edge.

At least part of the hinge portion is thicker than the connection portion such that the hinge portion comprises a proximal edge from which the connection portion extends. The proximal edge may thus be a ridge or ledge out of which the connection portion extends. The thickness of the thicker part or whole of the hinge portion may be substantially the same as or greater than, for example at least <NUM>% or <NUM>% of, the thickness of the data sheet. Thus the thicker part or whole of the hinge portion is preferably at least approximately <NUM>% as thick or at least approximately <NUM>% as thick as the data sheet. Preferably the thicker part extends across at least approximately <NUM>%, at least approximately <NUM>%, at least approximately <NUM>% or the whole of the hinge portion. Thus the proximal edge may extend across part or substantially all of the width of the hinge portion.

The hinge portion may comprise a distal edge located on the opposing side of the fold line to the proximal edge. The distal edge is preferably straight and nonparallel. A hinge portion height extending between the proximal and distal edges may vary along a width of the hinge portion.

Preferably the proximal edge has a proximal edge profile which is preferably nonlinear. The proximal edge profile may comprise at least one proximal edge section and the proximal edge profile and/or at least one proximal edge section may extend nonparallel to the fold line and/or the outer edge, outer edge profile and/or at least one outer edge section. The present disclosure also provides, in addition or alternatively to the inner edge profile being nonlinear and/or the inner edge being nonparallel to the outer edge and/or fold line, a security sheet comprising a data sheet and an attachment layer attached to and extending from the data sheet for attaching the data sheet in a security document, wherein the attachment layer comprises: a connection portion located in and/or over the data sheet; and a hinge portion extending from the data sheet, wherein at least part of the hinge portion is thicker than the connection portion to form a proximal edge proximal an inner edge of the data sheet and from which the connection portion extends, wherein the proximal edge comprises a nonlinear proximal edge profile.

The proximal edge is preferably proximal to, opposes and/or abuts the inner edge of the data sheet. The inner and proximal edge profiles may substantially match each other, be meshed with each other and/or abut along substantially all of their lengths. In particularly preferred embodiments, at least one proximal edge section of the proximal edge of the hinge portion, and preferably the entire proximal edge, is aligned with, is located adjacent to, is the inverse shape of, is meshed with and/or abuts at least one inner edge section of the inner edge, and preferably the entire inner edge, of the data sheet. Preferably, at least one proximal edge section extends inwardly into the hinge portion and at least one inner edge section extends outwardly from the data sheet into the at least one inwardly extending proximal edge section or vice-versa. However, the proximal and inner edges may not be aligned with one another along at least part of their lengths, such as by having different proximal and inner edge profiles, and/or may be separated from one another along at least part of their lengths.

The inner and/or proximal edge profiles may be periodic by comprising a plurality of repeating inner and/or proximal edge sections having the same shape, optionally in repeating sequences of inner and/or proximal edge sections with different shapes. Thus the inner and/or proximal edge profiles may be in the shape of a repeating waveform and may comprise a sinusoid, sawtooth wave, cycloid, a square wave, a triangular wave and the like. The inner and/or proximal edge profiles may be aperiodic by comprising a plurality of different inner and/or proximal edge sections and/or by having no substantially repeating sequences therein.

The plurality of inner and/or proximal edge sections may be the same as each other, such that the respective edge profile is periodic, or may be different from one another, preferably in an aperiodic manner such that the respective edge profile is aperiodic. Preferably inner and/or proximal edge profile comprises at least five, at least ten or at least fifteen sections. Preferably the width of at least one or each inner and/or proximal edge section is at least approximately <NUM>, at least approximately <NUM> or at least approximately <NUM> and/or is less than or equal to approximately <NUM>, less than or equal to approximately <NUM> or less than or equal to approximately <NUM>.

Preferably at least one inner and/or proximal edge section: extends inwardly into and/or outwardly from the data sheet and/or hinge portion; and/or comprises at least one straight, curved, convex or concave inner and/or proximal edge section. Preferably at least one inner and/or proximal edge section comprises: at least one of a tooth, sinusoid, castellation (e.g. a rectangular or square tooth) and/or triangular tooth.

It is noted that the edge profiles and sections may not exactly confirm to such shapes due to manufacturing tolerances, so the present disclosure refers to the edge profiles and sections as comprising such shapes in terms of their appearance being generally according to such shapes. For example, if the hinge portion comprises a textile as discussed below, the proximal edge profile may not be a perfect shape (e.g. a perfect cycloid) initially and may also change slightly during manufacture as plastic, as discussed below, is pressed against the proximal edge. Thus the references in the present disclosure to the edge profiles and sections forming certain shapes should be interpreted according to their overall appearance with tolerances around those shapes.

The data sheet is preferably rigid, comprises a plastic and is formed from a plurality of plastic layers overlying one another and attached together. Preferably forming the data sheet comprises applying heat and/or pressure, such as by welding or lamination, to the at least one plastic layer and attachment layer such that they are attached together. In the case of the data sheet being formed from a plurality of plastic layers, they may be fused together during such application. One or more plastic layers may be at least partially opaque, at least partially transparent and/or laser markable. The attachment layer is attached between adjacent plastic layers and/or at an outer surface of at least one plastic layer such that the connection portion is at least partially embedded in the data sheet. Thus preferably forming the data sheet and attaching the attachment layer occurs simultaneously. The plastic of the data sheet and plastic layers may comprise at least one of a thermoplastic polymer, polycarbonate, polybutylene terephthalate, polyester, polyethylene, polypropylene, polyvinyl chloride, a co-polymer comprised of any of the previous thermoplastic polymers and the like.

Preferably, the inner edge is formed into the inner edge profile being nonlinear, and/or nonparallel to the fold line and/or outer edge, during the application of heat and/or pressure to the at least one plastic layer and attachment layer. Thus the inner edge may be linear, and/or parallel to the outer edge and/or fold line, prior to the application of heat and/or pressure. The proximal edge may have substantially the same proximal edge profile before and after the application of heat and/or pressure. Such a manufacturing step results in the inner and proximal edges abutting in a particularly tight fit such that removing the data sheet along the interface between them is more difficult. During the application of heat and/or pressure the at least one plastic layer may be substantially softened and the inner edge may be moulded or pushed into conformity with the proximal edge. In particular, the inner edge may migrate into at least one inwardly extending proximal edge section to form at least one outwardly extending inner edge section or vice-versa. Thus prior to such application only part of the inner edge may abut the proximal edge and after such application substantially all of the inner edge abuts the proximal edge. Alternatively, the inner edge may be pre-formed or pre-cut into the nonlinear inner edge profile prior to attachment to the attachment layer.

Preferably the at least one plastic layer does not migrate over the hinge portion, for example by the hinge portion being at least the thickness of the at least one plastic layer prior to application of heat and/or pressure. However, in some embodiments the at least one plastic layer, or one or more of the plastic layers, may migrate over part of the proximal edge and/or hinge portion, such as if part of the proximal edge and/or hinge portion are thinner than the at least one plastic layer prior to lamination. For example, the proximal edge may vary in thickness and/or may only extend along part of the hinge portion, such that the plastic can flow around it.

Preferably the hinge portion and/or attachment layer comprises a textile, which is preferably woven or knitted and comprises at least one yarn. A textile is preferable because if a fraudster cuts through the hinge portion the textile will unravel and therefore is very difficult to reassemble. Furthermore, using a textile assists in ensuring a tight fit between the inner and proximal edges such that a fraudster is effectively forced to attempt to cut a straight line rather than cut along and between the inner and proximal edges. The textile may be formed from the at least one yarn by weaving, knitting, sewing or another interlacing method. In the present disclosure "knitting" refers to forming closed, interlocked loops between yarns. Preferably the knitting is crochet knitting and each interlock comprises a crochet knitting stitch. In the present disclosure "yarns" are long, thin strand of materials forming part of the textile. For example, the at least one yarn may comprise a material, such as a plant, mineral, animal or synthetic material, selected from at least one of cotton, wool, linen/flax, bamboo, silk, jute, modal, polyamide, polyester, viscose, glass, polypropylene, polyaramid, polyurethane, nylon, bonded nylon, rayon, acrylic, polycotton and/or other suitable fibres. The at least one yarn may be substantially circular, trilobal, fibrillated, grooved, dog bone or multiform in cross section. A ply structure of the at least one yarn may be single or one-ply (i.e. single strands of fibres twisted together or single filament strands), multi-ply (i.e. a plurality of single yarns twisted together) or cord yarns (i.e. a plurality of multi-ply yarns twisted together in a twist direction).

The textile of at least the hinge portion and/or of the attachment layer preferably comprises a plurality of interlaced, knitted, woven, stitched, overlapping or otherwise integrated wefts and warps formed from the at least one yarn. During manufacture, a plurality of warp yarns may be fed by a machine into contact with the weft yarns for interlacing therewith. Preferably the machine is a knitting machine and more preferably a crochet knitting machine. The warps may extend substantially parallel to one another and/or the fold line. The wefts may extend substantially parallel to one another and/or may be substantially perpendicular to the warps and/or fold line. The connection portion may comprise at least portions of the wefts, referred to as connection wefts, extending out of the hinge portion. The connection portion may instead comprise a mesh of both wefts and warps, rather than only the connection wefts, such that the entire attachment layer is a meshed textile. Although the connection wefts are preferably part of the textile, they may instead comprise strips, a film and/or other elongate bodies extending from the hinge portion.

The hinge portion preferably comprises a textile having at least one infill yarn forming the at least one proximal edge section and/or proximal edge. In particular, the at least one infill yarn may comprise at least one infill yarn section at the proximal edge forming the at least one proximal edge section. The at least one infill yarn may extend nonlinearly and the at least one infill yarn section may have any of the shapes discussed above in respect of the at least one proximal edge section. The or each infill yarn may extend continuously through the hinge portion to form a plurality of wefts of the hinge portion and may be interlaced with at least two parallel warps. Each warp may comprise a plurality of loops, wherein at least one, preferably at least two, wefts extend through and are interlocked in each loop. The hinge portion may be thicker than the connection portion by virtue of the at least one infill yarn being thicker than the connection wefts and/or by having a higher density or thread count of warps and/or wefts.

Preferably the same at least one infill yarn may form a plurality or all of the proximal edge sections. Preferably the at least one infill yarn extends substantially along a periodic waveform, such a sinusoid, and at least one peak or trough of the periodic waveform (e.g. the curve of a sinusoid) is located at the proximal edge to form the at least one yarn section. The at least one infill yarn preferably extends along the periodic waveform between the proximal and distal edges. In the case of a plurality of infill yarns, the infill yarns may extend parallel and adjacent to one another along the periodic waveform. Preferably the at least one infill yarn comprises at least one curved yarn section at the proximal edge and at least one opposing curve may be located at the distal edge such that it follows a sinusoidal periodic waveform. Alternatively, different infill yarns may form adjacent or different proximal edge sections and the textile of the header may comprise any other suitable arrangement in which at least one infill yarn forms the at least one proximal edge section.

In a particularly preferred embodiment the data sheet comprises a plastic and the hinge portion comprises a textile having at least one infill yarn forming at least one proximal edge section. During the application of heat and/or pressure the plastic of the at least one plastic layer forming the data sheet is pushed into spaces defined at the proximal edge by the at least one infill yarn.

The security document of the present disclosure may be a security booklet, such as a passport, passbook, identification document, certificate, licence, cheque book or the like. The data sheet preferably comprises personal data relating to a holder of the security sheet or security document. The personal data may comprise a name, date of birth, portrait and/or machine readable data and may be printed and/or laser marked on the data sheet.

By way of example only, embodiments of a security sheet, a security document and a method in accordance with the present disclosure are now described with reference to, and as shown in, the accompanying drawings, in which:.

<FIG> and <FIG> illustrate a security document <NUM>, in this case a passport, in accordance with the present disclosure. The security document <NUM> comprises a security sheet <NUM>, illustrated in further detail in <FIG>, foldable about and attached along a fold line <NUM> by stitching to a plurality of leaves <NUM>. The plurality of leaves <NUM> may comprise a fibrous substrate, for example paper and/or cotton and may form visa pages. The security document <NUM> also comprises a cover <NUM>, which is foldable about and attached to the fold line <NUM> and/or is adhered to an outer leaf (not shown) located on the outside of the leaves <NUM> and security sheet <NUM>.

The security sheet <NUM> comprises a data sheet <NUM> formed from a plurality of plastic layers <NUM> laminated together into a rigid plastic substrate comprising personal data <NUM> and an attachment layer <NUM> attached to the data sheet <NUM>. The data sheet <NUM> extends across a width from an inner edge <NUM>, located proximate the fold line <NUM>, to an outer edge <NUM>, distal to the fold line <NUM>. The inner and outer edges <NUM>, <NUM> extend between parallel side edges <NUM>, <NUM> of the data sheet <NUM>. The data sheet <NUM> extends across a thickness between substantially planar first and second outer surfaces <NUM>, <NUM>. The inner edge <NUM> has a nonlinear inner edge <NUM> profile or outline split into a plurality of (in this case over ten) substantially identically shaped inner edge sections <NUM> extending, in this example, nonparallel to the fold line <NUM> and outer edge <NUM>. Each inner edge section <NUM> is curved and concave and extends inwardly into the data sheet <NUM>. The concave inner edge sections <NUM> are connected to one another at their ends such that the inner edge <NUM> profile substantially comprises a periodic cycloid. The inner edge sections <NUM> may instead be defined as the teeth defined between the curves. As a result, the data sheet <NUM> height, being the distance between the inner and outer edges <NUM>, <NUM>, varies along the width of the data sheet <NUM>.

The attachment layer <NUM> is configured to securely connect the attachment layer <NUM> to the data sheet <NUM> and to the rest of the security document <NUM>. The attachment layer <NUM> is thus preferably flexible, substantially resistant to plastic deformation and tear resistant and may comprise a substantially elongate sheet or body as illustrated. The attachment layer <NUM> comprises a connection portion <NUM> extending from a hinge portion <NUM>. The connection portion <NUM> is located in or on and attached to the data sheet <NUM> and extends at least partially into the data sheet <NUM> (i.e. from the inner edge <NUM> towards the outer edge <NUM>). The hinge portion <NUM> is located outside of the data sheet <NUM> and comprises the entire part of the attachment layer <NUM> located outside of the data sheet <NUM>. The hinge portion <NUM> comprises the fold line <NUM> and thus the fold of the attachment layer <NUM>.

The hinge portion <NUM> extends between a proximal edge <NUM> abutting and adjacent to the inner edge <NUM> of the data sheet <NUM> and a distal edge <NUM> on the opposing side of the fold line <NUM> to the proximal edge <NUM>. In the illustrated embodiment the proximal edge <NUM> extends across the whole width of the attachment layer <NUM> by virtue of the entire hinge portion <NUM> being thicker than the connection portion <NUM>. However, only part of the hinge portion <NUM> (e.g. only a central portion) may be thicker than the connection portion <NUM> such that the proximal edge <NUM> only extends across part of the width of the attachment layer <NUM> and hinge portion <NUM>. As best illustrated in <FIG>, the connection portion <NUM> extends from the proximal edge <NUM>, particularly from the within of the thickness of the hinge portion <NUM> such that the proximal edge <NUM> extends on either side of the connection portion <NUM>. Alternatively, the connection portion <NUM> may extend from the top or bottom of the thickness of the hinge portion <NUM> such that such that the proximal edge <NUM> extends on only one side of the connection portion <NUM>.

The proximal edge <NUM> has a nonlinear proximal edge <NUM> profile or outline comprising a plurality of (in this case over ten) proximal edge sections <NUM> extending, in this example, nonparallel to the fold line <NUM> and outer edge <NUM>. As illustrated, each proximal edge section <NUM> may be curved and convex and may extend inwardly into the hinge portion <NUM>. The convex proximal edge sections <NUM> are connected to one another at their ends such that the proximal edge <NUM> profile substantially comprises a periodic cycloid. The inwardly extending proximal edge sections <NUM> may also be defined as inwardly extending proximal edge sections <NUM> at the recessed or convex parts of the proximal edge <NUM> profile (i.e. between the convex proximal edge sections <NUM>). As a result, the proximal edge <NUM> profile is nonlinear and the hinge portion <NUM> height, being the distance between the proximal and distal edges <NUM>, <NUM>, varies along the width of the attachment layer <NUM>. The proximal edge sections <NUM> of the entire proximal edge <NUM> are meshed with and abut the inner edge sections <NUM> of the entire inner edge <NUM>. Thus the cycloid of the proximal edge <NUM> profile is the inverse of that of the inner edge <NUM> profile.

A fraudster cannot cleanly separate the data sheet <NUM> from the hinge portion <NUM>, such as if they are attempting to replace the data sheet <NUM> with one containing fraudulent personal data <NUM> and particularly if they are attempting to perform a straight cut parallel to the fold line <NUM>. Referring to <FIG>, if a fraudster attempts to cut along a straight line parallel to the fold line <NUM> and extending between the peaks and troughs of the curved inner and proximal edge sections <NUM>, <NUM>, part of the hinge portion <NUM> will remain with the removed data sheet <NUM> and part of the data sheet <NUM> will remain with the attachment layer <NUM>. Similar unwanted remaining parts of the data sheet <NUM> or hinge portion <NUM> will also result if the fraudster attempts to cut along a straight line above or below the inner and proximal edges <NUM>, <NUM> through the hinge portion <NUM> or the data sheet <NUM>. In each case, the remaining parts of the hinge portion <NUM> or data sheet <NUM> would cause substantial difficulties for the fraudster attempting to replace the data sheet <NUM> and are also likely to result in discontinuities or the like that can be identified by a document inspector.

However, the difficulty of separating the data sheet <NUM> from the hinge portion <NUM> is also increased by the embodiment shown in <FIG> in which the attachment layer <NUM> comprises a textile. By having a textile hinge portion <NUM> the proximal edge <NUM> can be formed tightly against the inner edge <NUM>, thereby increasing the difficulty of cutting along the inner and proximal edges <NUM>, <NUM>. The attachment layer <NUM> and the hinge portion <NUM> comprise a textile, which may have a mesh of interlaced wefts <NUM> and warps <NUM> in at least the hinge portion <NUM>. The connection portion <NUM> comprises portions of wefts <NUM>, referred to as connection wefts <NUM>, as illustrated in <FIG>, at least partially embedded in the data sheet <NUM>. The plurality of connection wefts <NUM> are separated from an adjacent connection weft <NUM> by a spacing <NUM>. The connection wefts <NUM> comprise portions of the wefts <NUM> extending out of and forming the hinge portion <NUM> as in <FIG> (although visible in the Figures, the connection wefts <NUM> may or may not be visible at the first and/or second outer surface <NUM>, <NUM> depending upon the opacity of the data sheet <NUM>). The connection portion <NUM> is therefore firmly connected to the data sheet <NUM> by a frictional force applying a resistance to any attempted removal of the attachment layer <NUM> from the data sheet <NUM>.

The hinge portion <NUM> comprises a plurality of, in this case four, infill yarns <NUM>, <NUM>, <NUM>, <NUM>, forming the proximal edge <NUM>. An infill yarn <NUM> comprises a plurality of convex infill yarn sections <NUM> forming the plurality of convex proximal edge sections <NUM>. The infill yarns <NUM>, <NUM>, <NUM>, <NUM> extend adjacent to one another substantially along a periodic sinusoid as illustrated. The infill yarns <NUM>, <NUM>, <NUM>, <NUM> each extend continuously and form a plurality of wefts <NUM> of the hinge portion <NUM>. The hinge portion <NUM> comprises a plurality of, in this case five, warps <NUM> and the warps <NUM> may be interlaced with the wefts <NUM> by knitting as illustrated. Each warp <NUM> comprises a plurality of loops and two wefts <NUM> extend through and are interlocked in each loop. The connection wefts <NUM> extend between and/or over the infill yarns <NUM>, <NUM>, <NUM>, <NUM> and are also interlocked in the loops of the warps <NUM>. Each connection weft <NUM> is substantially thinner than the infill yarns <NUM>, <NUM>, <NUM>, <NUM> such that the hinge portion <NUM> is thicker than the connection portion <NUM>.

The security sheet <NUM> may be formed by the connection together of the attachment layer <NUM> and at least one plastic layer <NUM> forming the data sheet <NUM> by, for example, by the application of heat and/or pressure, such as during lamination and/or welding, by adhesion and/or any other suitable method. <FIG>, <FIG> and <FIG> illustrate a plurality of plastic layers <NUM> (in <FIG> only an outer plastic layer <NUM> is shown) and attachment layer <NUM> prior to attachment. During lamination or welding heat and/or pressure are applied to fuse or push the plurality of plastic layers <NUM> together and the plastic of at least one plastic layer <NUM> is pushed through the at least one spacing <NUM> between the connection wefts <NUM>, through mesh openings of the mesh or through the textile (depending upon the construction of the connection portion <NUM>). As illustrated in <FIG>, the attachment layer <NUM> may be located on the first and/or second outer surface <NUM>, <NUM> formed by the outer plastic layers <NUM> prior to attachment. At least one strip <NUM> may overlap at least part of the connection portion <NUM> (<FIG>). During attachment, the connection portion <NUM> and, if present, at least one strip <NUM> are pressed into the first and/or second outer surface <NUM>, <NUM> such that they are at least partially attached at, embedded in, adjacent to and/or overlapping the first outer surface <NUM> of the data sheet <NUM> (<FIG>). In particular, the connection portion <NUM> and, if present, at least one strip <NUM> are attached to or at least partially embedded within the data sheet <NUM> such that they forms part of the first outer surface <NUM> of the data sheet <NUM>. Alternatively, as illustrated in <FIG>, the connection portion <NUM> may be attached between adjacent plastic layers <NUM> prior to the attachment (<FIG>) such that it is located within the thickness of the data sheet <NUM> after the attachment (<FIG>). The lamination may be performed using any suitable method and may be a substantially in-line method, similar to that of <CIT> and <CIT>, in which a plurality of security sheets <NUM> are formed continuously.

The inner edge <NUM> is linear and parallel to the fold line <NUM> and outer edge <NUM> prior to the application of heat and/or pressure, such as by lamination or welding, and instead is formed into the inner edge <NUM> profile being nonlinear and nonparallel to the fold line <NUM> and outer edge <NUM> during such application. As illustrated in <FIG>, <FIG> and <FIG>, the inner edge <NUM> formed by the plurality of plastic layers <NUM> prior to application is straight and thus does not mesh with the proximal edge <NUM> or extend into the inwardly extending proximal edge sections <NUM>. Only part of the inner edge <NUM> abuts the proximal edge <NUM>, if at all. However, under the application of heat and/or pressure, the plurality of plastic layers <NUM> are softened and pushed into (see arrows <NUM> in <FIG>, <FIG> and <FIG>) the inwardly extending proximal edge sections <NUM> such that the inner edge <NUM> changes shape and is meshed with the proximal edge <NUM> formed by the at least one infill yarn <NUM>. Thus the inner and proximal edges <NUM>, <NUM> form an abutting interface as illustrated in <FIG>, <FIG> and <FIG>. Due to the hinge portion <NUM> being formed from a textile, which may be flexible, it will be appreciated that during manufacture the proximal edge <NUM> profile may change slightly as the yarns of the textile are moved by the plastic of the plastic layers <NUM> pressing against them. However, the overall shape of the proximal edge <NUM> remains substantially or broadly a cycloid.

In the illustrated embodiment the hinge portion <NUM> is substantially the same thickness as the data sheet <NUM> such that the softened plastic does not extend over the hinge portion <NUM>. Furthermore, all of the plastic layers <NUM> have extended by the same amount towards the hinge portion <NUM> during the application of heat and/or pressure. However, plastic layers <NUM> may extend by different amounts into the hinge portion <NUM>, such as if the proximal edge <NUM> is nonparallel to the thickness of the hinge portion <NUM> (i.e. such that the hinge portion <NUM> height varies through the hinge portion <NUM> thickness and/or the proximal edge <NUM> varies in thickness).

Claim 1:
A security sheet (<NUM>) comprising a data sheet (<NUM>) and an attachment layer (<NUM>) for attaching the data sheet (<NUM>) in a security document (<NUM>), wherein:
the data sheet (<NUM>) is formed from a plurality of plastic layers (<NUM>) overlying one another and attached together, and extends between an inner edge (<NUM>) and an outer edge (<NUM>), wherein the data sheet (<NUM>) comprises a data sheet height extending between the inner and outer edges (<NUM>, <NUM>) and a data sheet width perpendicular to the data sheet height;
the data sheet (<NUM>) is attached to the attachment layer (<NUM>) at the inner edge (<NUM>);
the attachment layer (<NUM>) comprises a hinge portion (<NUM>) located outside of the data sheet (<NUM>) and a connection portion (<NUM>) extending from the hinge portion (<NUM>) into and/or onto the data sheet (<NUM>);
the attachment layer (<NUM>) is attached between adjacent plastic layers (<NUM>) of the plurality of plastic layers (<NUM>) of the data sheet (<NUM>) and/or the attachment layer (<NUM>) is attached at and/or embedded in an outer surface (<NUM>, <NUM>) of the data sheet (<NUM>) such that the connection portion (<NUM>) is at least partially embedded in the data sheet (<NUM>); and
the inner edge (<NUM>) has a nonlinear inner edge (<NUM>) profile such that the data sheet height varies along the data sheet width, the inner edge (<NUM>) profile being nonlinear by being not straight and by comprising at least one curve and/or at least two straight lines at a non-straight angle to one another;
characterised in that at least part of the hinge portion (<NUM>) is thicker than the connection portion (<NUM>) such that the hinge portion (<NUM>) comprises a proximal edge (<NUM>) from which the connection portion (<NUM>) extends.