VALUABLE DOCUMENT PROVIDING A HAPTIC EFFECT

Abstract

 The present invention relates to a valuable document and a method to produce this document. The valuable document comprises fiber substrate having a front side, a reverse side, and a thickness between the front and the reverse side, the fiber substrate comprising a elongate strip of foil embedded in a thickness of the fiber substrate. The elongate strip of foil comprises at least one perforation. The perforation is permeable for and covered by fibers of the fiber substrate. The perforation is configured to provide a haptic effect on the front and/or the reverse side of the fiber substrate.

Description

[0001] The present invention relates to a valuable document which provides a haptic effect and a method to produce this document.

[0002] It is known in the art to incorporate pads or strips of a foil into a paper (or paper-like) substrate of security or valuable documents, as for example banknotes. These parts of foil can comprise security elements. The foil and in particular the security elements prevent simple copying of the banknotes by copying machines. The combination or integration of foil into a paper substrate during manufacturing generally creates challenges regarding the properties of the valuable document and the security element. Usually, the strip of foil including its specifics is hidden or overprinted in order to not be obvious to a user such that difficulties with regard to counterfeit actions are increased. Consequently, in this case the expectation of a haptic effect is rather low. In an alternative, several strips of foils may be incorporated into a paper substrate each specifically designed for different purposes. However, the incorporation of multiple strips of foils makes the production process complex and causes additional costs.

[0003] The objective technical problem to be solved can be considered to consist in providing a valuable document having improved anti-counterfeiting properties and being producible at high efficiency. The problem is solved by the subject matter of the independent claim. Preferred embodiments are indicated within the dependent claims and the following description, each of which, individually or in combination, may represent aspects of the invention. Some specifics of the present invention are described with regard to corresponding (production) methods. However, the advantages and preferred embodiments described with regard to the indicated devices are correspondingly to be transferred to the according methods and vice versa.

[0004] According to a first aspect, a valuable document is provided. The valuable document comprises a fiber substrate having a front side, a reverse side, and a thickness between the front and the reverse side. The fiber substrate may also be referred to as fibrous material. The fiber substrate comprises an elongate strip of foil embedded in the thickness of the fiber substrate. The elongate strip of foil comprises at least one perforation. The perforation is permeable for fibers of the fiber substrate. The perforation is covered by fibers of the fiber substrate. In particular, the perforation may be covered when the valuable document is in its manufactured state. The perforation is configured to provide a haptic effect on the front and/or the reverse side of the fiber substrate. In particular, the haptic effect may be provided when the valuable document is in its manufactured state. The haptic effect may be utilized as a security feature thereby enhancing the valuable document from a security point of view.

[0005] The haptic effect may be recognizable by an unbiased human observer when the valuable document is in its manufactured state. The unbiased human observer may be considered an average person having medium haptic or tactile sensing capabilities.

[0006] The valuable document usually comprises a nearly two dimensional shape with a low thickness in a direction perpendicular to the first and opposite second surface of the document. Although this thickness may be low and hardly recognizable by means of the naked human eye, the elongate strip of foil may be embedded in the thickness. With regard to the before mentioned aspects, the thicknesses are determined according to a direction in which the valuable document comprises the smallest dimension. The perforation of the strip of foil may usually be arranged according to the direction of the low thickness (smallest dimension) of the document. Moreover, the strip of foil including the at least one perforation may be covered by the fiber substrate such that it is not recognizable by the human eye at daylight under normal conditions. In this case, normal conditions refer to a scenario in which no additional technical analysis is performed.

[0007] The elongate strip of foil may be in register with the fiber substrate. In particular, the elongate strip of foil may be kept in register with fibers of the fiber substrate during the manufacturing process. "In register" means that the relative positions of the paper web constituting the valuable document and the strip of foil are all aligned as precise and reliable as possible.

[0008] The perforation being permeable for fibers of the fiber substrate refers to the paper production process in which a paper web is generated from a pulp while the elongate strip of foil may be kept in register with the paper web. During this manufacturing technique fibers may flow or move through the perforation from a first side of the strip of foil towards a second opposite side.

[0009] The valuable document may be paper, such as security paper, containing a strip embedded in the thickness of the paper. The valuable document may also be a security document made from such paper.

[0010] The valuable document may comprise a first thickness between the front and the reverse side in a perforated region of the elongate strip of foil. The valuable document may also comprise a second thickness between the front and the reverse side in a non-perforated region of the elongate strip of foil. The first thickness may be different from the second thickness. In other words, the valuable document may vary in thickness at a location of a perforation of the embedded strip of foil compared to a location at which the embedded strip of foil does not comprise a perforation. The thickness difference may be very low. In particular, the thickness difference may be so small that it is not recognizable by the naked human eye at daylight under normal conditions. However, the tactile sensitivity of a human being may be sufficient to recognize the thickness difference, e.g. a curvature effect of the valuable document caused by an edge of the perforation. Accordingly, the perforation may be visually hidden under non-sophisticated analysis conditions while it may be rather easily recognizable using tactile based sensing. Hence, the security of the valuable document may be further improved.

[0011] The elongate strip of foil may differ in one, two, three or more properties from a remainder of the valuable document. The one, two, three or more properties may be selected from a group consisting of a bending coefficient, a hardness, a flexibility, and a pressure sensitivity. The haptic effect may be based on a property difference of the one, two, three or more properties as specified hereinbefore. These properties are particularly suitable for tactile investigation and for tactile based recognition of the perforation. For example, when pressing on the valuable document, the user may feel differences with regard to the hardness between a location where a peroration is arranged and a location where no perforation is present but the embedded strip of foil still is. Similar differences may be recognizable with regard to the remaining properties. Accordingly, the security of the valuable document may be improved, even if the document comprises no thickness variations across its surfaces.

[0012] The at least one perforation may have a geometric shape. The geometric shape may be individually selected any may comprise at least one out of a circle, a rectangle, a square, an ellipse, a trapeze, a diamond, a rhombus, and a parallelogram. Accordingly, the perforation may comprise a shape well-known to most humans such that the shape may be simpler to recognize.

[0013] For a plurality of perforations, the perforations can independently vary in size with regard to each other. This means that the perforations may have same shapes and same or different dimensions in a two-dimensional plane. In an alternative, the perforation may have different shapes and same or different dimensions in a two-dimensional plane.

[0014] The at least one perforation may comprise a first width in a first direction. The elongate strip of foil may comprise a second width in the first direction. The first direction may in particular be along the length or the width of the valuable document. The first width of the perforation may be equal to or more than 5% of the second width of the elongate strip of foil in the first direction. Preferably, the first width may be equal to or more than 10% of the second width of the elongate strip of foil in the first direction. The elongate strip of foil may comprise a length and a width perpendicular to the length, the width being smaller than the length. The first direction may then be oriented along the width of the strip of foil. The above-mentioned relative widths constitute a minimum size of the perforation relative to the strip of foil such that the possibility of recognizing the perforation is improved.

[0015] The strip of foil may comprise a minimum width along the first direction of 2cm. The strip of foil may also comprise a maximum width along the first direction of 4cm.

[0016] The perforations can also have a combined open area relative to the area of the strip of foil. The combined open area may be considered the sum of all singles areas formed by the independent perforations. The combined open area may be equal to or more than 1 % of the area of the strip of foil, preferably equal to or more than 3% of the area of the strip of foil, more preferably equal to or more than 10% of the area of the strip of foil. The combined open area may also be equal to or less than 50% of the area of the strip of foil, preferably equal to or less than 30% of the area of the strip of foil, more preferably equal to or less than 20% of the area of the strip of foil.

[0017] In an alternative, the strip of foil may be exposed (non-covered) and the perforations may be established within the exposed region. In this case, the combined open area may be equal to or more than 2% of the exposed area of the strip of foil, preferably equal to or more than 5% of the exposed area of the strip of foil, more preferably equal to or more than 10% of the exposed area of the strip of foil. The combined open area may also be equal to or less than 50% of the exposed area of the strip of foil, preferably equal to or less than 30% of the exposed area of the strip of foil, more preferably equal to or less than 20% of the exposed area of the strip of foil.

[0018] In an alternative, the valuable document may comprise a length and a width perpendicular to the length in a specific direction (in the following: second direction), the width being smaller than the length. In this case, the width of the perforation may be equal to or more than 1 % of the width of the valuable document (in the following: third width) in the second direction. In this case, the width of the perforation may also be determined along the second direction. More preferably, the width of the perforation may be equal to or more than 5% of the width in the second direction.

[0019] The elongate strip of foil may comprise a plurality of perforations. A single perforation may be challenging to recognize. Having included a plurality of perforations, the chances of recognizing the perforations are increased.

[0020] The plurality of perforations may form a geometric pattern (array). A pattern of perforations may be easier to recognize due to the alternating variations concerning the haptic effect. The pattern may comprise itself a geometric shape, such as a circle, a rectangle, a square, an ellipse, a trapeze, a diamond, a rhombus, numbers, letters, and a parallelogram.

[0021] The geometric pattern may comprise columns and/or rows at least partially comprising regularly arranged perforations. The columns and rows can be arranged along directions corresponding to a length and a width of the valuable document. Along the columns and rows there can be multiple perforations arranged. A pattern is usually simple to recognize if variations concerning the underlying properties are being continuously distributed. Hence, the so-designed pattern is usually recognized at a high chance.

[0022] In an alternative, the perforations can be randomly distributed across the strip of foil.

[0023] The pattern may be different to the so-called intaglio features or an intaglio effect (printing) where multiple parallel rows and/or columns of ink are applied by gravure printing and thereby providing a haptic effect as a whole. In contrast to intaglio printing, the present application aims at providing a direct haptic effect which is provided by the perforations instead of an indirect haptic effect provided by the applied ink.

[0024] The material of the elongate strip of foil may comprise or consist of one or more suitable polymeric foil materials to be incorporated into paper-based documents, in particular valuable documents, such as banknotes, wherein the material is preferably selected from a group consisting of polyamide, polyethylene, and polyester. Foils made of these materials are in particular easy to manufacture and well suited for incorporation into a paper-based document.

[0025] The haptic effect may be machine readable using a suitable detector, such as an image detector, or any other suitable detector. Accordingly, verification of the valuable document may also be based on auxiliary devices. Such devices are usually capable of investigating a high number of document at short time scales.

[0026] According to a second aspect, the elongate strip of foil may be uncovered or substantially uncovered by fibers of the fiber substrate forming an exposed area of the elongate strip of foil on the front and/or the reverse side of the valuable document. The exposed area may form a window area of the valuable document comprising the elongate strip of foil which is in register with the window area. Optionally, the elongate strip of foil comprises in the exposed area one or more security elements selected from a group consisting of an optical security element, a luminescent security element, including a fluorescent, a phosphorescent and an electroluminescent security element, and a magnetic security element. The terms "exposed" or "uncovered" mean that the window area may be at least partially free or clean of fibers of the fiber substrate so as to provide a window area for a security element of the elongate strip of foil which is in register with the window.

[0027] The window area can be free of perforations. Accordingly, the strip of foil can be made such that perforations are present only in non-exposed areas (non-window areas) of the strip of foil. In this case, the perforations would not be exposed and thus detectable by a human eye, but embedded in the valuable document (covered) and, thus, protected from being viewed by a human eye.

[0028] The exposed or uncovered areas can generally and at least partially be generated by a watermarking technique.

[0029] The window can at least horizontally (in a first direction) be in register with the elongate strip of foil. However, it is more advantageous if all components, i.e. paper web, strip of foil, window areas, exposed areas and any eventual layer of the paper web are in register.

[0030] The elongate strip of foil may comprise at least one perforation arranged in the exposed area. Since the exposed area may also be visually recognizable by the user, the perforation may be noticed on a tactile as well as a visual basis. Of course, the perforation arranged in the exposed area is not covered by fibers of the fiber substrate, in particular not when the valuable document is in its manufactured state.

[0031] Furthermore, as the exposed area comprises at least one perforation, the fibers of the mould layer, the layer in which the strip of foil is embedded, can then protrude through at least one opening from a first side towards the opposite second side. This provides increased flexibility regarding the creation and properties of security features in the window area.

[0032] The exposed area may be obtainable by selective local repulsion of fibers. The local repulsion may be induced by application of a fluid, in particular compressed air and/or water.

[0033] The local repulsion may be induced by application of a fluid (in form of a jet through a nozzle).

[0034] The fluid may be applied continuously and/or pulse-wise in pulses of adjustable duration and/or synchronized in relation to a target position of the window area.

[0035] The uncovered area can at least partially be generated by locally selective inhibition of substrate formation on the elongate strip of foil. The locally selective inhibition can also be physically and/or chemically induced. The locally selective inhibition can further at least partially be induced by local surface treatment of the elongate strip of foil.

[0036] In an advantageous aspect, the locally selective inhibition can be provided by a hydrophobic or super-hydrophobic layer/structure. If a super-hodrophobic layer is used, the water droplet/solid surface snap-in forces - measured e.g. using the micro balance in a tensiometer - become zero because the surface tension of the water, hence its internal cohesion, is stronger than the reference surface wettability. Another way to define super-hydrophobic is that the advancing angle of the droplet on a reference surface (not its static angle) is greater than 145° when the liquid is water.

[0037] The exposed or uncovered area can also be generated by removal of fibers by suction, in particular discontinuous suction.

[0038] Optionally, residual fibers may be removed by a rotating brush from at least the exposed area. Accordingly, the cleanliness of the exposed area may be improved.

[0039] According to an aspect, some additional fibers can be arranged or locally accumulated in off-limit zones in order to compensate fiber depletion on vicinal areas of the window.

[0040] The elongate strip of foil may also comprise a plurality of exposed areas, each providing a window area.

[0041] The accumulation may also be referred to as "bump" of fibers created between two windows. This area is also referred to as "off-limit" zone. In others words, any regions coinciding with the strip of foil but being laterally located outside the exposed area may be referred to as "off-limit" zone.

[0042] Areas of accumulated fibers may be evened up by a rotating brush to create bumps.

[0043] The elongate strip of foil may be transparent or semi-transparent at least in the area of the window. Accordingly, at the exposed area a view through the valuable document, meaning through the strip of foil and optionally through a perforation arranged in the exposed area, may be possible. Accordingly, visual inspection may be adapted to the needs.

[0044] All features and embodiments disclosed with respect to the second aspect of the present invention are combinable alone or in (sub-)combination with any one of the first aspect of the present invention including each of the preferred embodiments thereof, provided the resulting combination of features is reasonable to a person skilled in the art.

[0045] According to a third aspect, the fiber substrate may comprise a mould layer and a short former layer and the elongate strip of foil may then be embedded in the mould layer. This aspect is advantageous, as it has turned out that a two layer configuration has better properties than a single layer configuration. The exposed area of the embedded strip of foil may then be arranged in the mould layer such that at least one side of the exposed area may be visible from outside of the valuable document. In contrast, one side of the exposed area may optionally be covered by the short former layer.

[0046] The elongate strip of foil may be transparent or semi-transparent at least in the area of the window. Accordingly, the short former layer may be visible from both sides of the valuable document within the exposed area.

[0047] A groove (or depression) can be arranged on one of the surfaces of the substrate. The groove, the embedded foil strip and, at least partially, the bumps can be aligned with each other such that the groove is at least substantially superposed. In other words, the groove and the bumps can substantially match and mutually compensate each other from a height aspect, if they are viewed perpendicular to the surface of the substrate (cross-sectional view).

[0048] The short former layer may be absent at least in a depletion zone. The depletion zone may be in register with the strip of foil. Accordingly, from the side of the short former layer, the mould layer and/or the embedded strip of foil may be visible. Also, the elongate strip of foil may be arranged such that at least one perforation coincides with the depletion zone in a cross-sectional view. Accordingly, this perforation may be visible from the side of the short former layer.

[0049] In an alternative, the short former layer may be absent in a depletion zone, wherein the depletion zone may be at least partially registered with the exposed area of the elongate strip of foil. In other words, the depletion zone may coincide with the exposed area in a cross-sectional view. In this regard, the short former layer may also form a window area. Hence, fibers of the mould layer may be visible through the window area from the side of the short former layer.

[0050] If a short former layer is used, another reason for the accumulation or bump of fibers consists in compensating the thickness difference brought in by the short former layer. In other words, fibers of the mould layer may be accumulated at the location of the depletion zone. Accordingly, the height difference determined by the depletion zone of the short former layer may be compensated by bumps of the mould layer.

[0051] The substrate or the plies of the substrate, in case of a multi layer substrate, may comprise cellulose fibers particularly cotton fibers and/or organic synthetic fibers and/or mineral fibers. The substrate can generally be fibrous as for example any paper-like substrate.

[0052] All features and embodiments disclosed with respect to the third aspect of the present invention are combinable alone or in (sub-)combination with any one of the first and second aspects of the present invention including each of the preferred embodiments thereof, provided the resulting combination of features is reasonable to a person skilled in the art.

[0053] According to a fourth aspect a method of manufacturing a substrate for a valuable document and a method of manufacturing a valuable document are provided. An at least partially porous or perforated strip of foil can be provided in a paper mould around a first cylinder. The first cylinder partially resides in a pulp. A paper web is generated from the pulp on an outer wall of the first cylinder by rotating the first cylinder. The pulp is dewatered through a permeable outer wall of the first cylinder. During the previous steps, the strip of foil is kept in register with the paper web, and fibers of the pulp/paper web may move through the perforation of the strip of foil from a first side to an opposite second side.

[0054] Optionally, fibers may be actively removed from at least one side of a window area included in the strip of foil. At the other side, which is the one in direct contact with the mould cover during manufacturing, the fibers deposition may be prevented/inhibited. Exemplarily, areas free of fiber can either be created by covering specific points, areas, or locations etc. on the wire mesh of the first cylinder. This can be achieved by protruding elements which may merely plug some or all openings in the wire mesh of the first cylinder. Thereby, the pulp is locally prevented from draining towards the inside of the first cylinder such that in those selectively chosen locations, no or less fibers accumulate. This leads to exposed areas (windows) of the strip of foil being established. The advantageous valuable document can then be manufactured from the substrate.

[0055] Preferably, a relief die mask (or a plurality of masks) can be mounted onto the first cylinder mould cover, against which the perforated strip of foil is pushed during the manufacturing process. The mask can further improve the prevention of unwanted fibres within the exposed area(s). Otherwise, fibres could get trapped between the mould cover and the strip of foil thereby decreasing the quality (cleanliness) of the exposed areas as well as the sharpness of their edges. Moreover, since the mask assists in locally obstructing the pulp flow, it is ensured that fibres cannot come back once the paper formation is achieved. Therefore, utilizing the mask, edges of the exposed area at the front side of the substrate may be better defined having improved sharpness since erratic fibres occupying portions/edge zones of the exposed area (window areas) can be avoided. The mask can also be correspondingly curved with regard to the first cylinder. In other words, the radii of the mask and the first cylinder can correspond to each other. Mounting of the mask to the cylinder can, e.g., be achieved by gluing and/or welding.

[0056] In an alternative, for improving the quality of the edges of the exposed areas, in particular their sharpness, a stenciled, virtually thickness-less mask (or a plurality of masks) may be applied onto the cylinder mould cover. The perforated strip of foil may then be kept in close contact along the full perimeter of the mould cover. Due to the normal permeability and drainage of the mould mesh and of the perforated strip of foil itself, the fibres can pass underneath and enrobe the perforated strip of foil all over, without the need of a loose gap. The areas on the mould cover where the stenciled mask inhibits the drainage are the only portions of the substrate where fibres cannot be deposited, thus creating the exposed areas (windows) according to a different approach. Similar as in case of the relief die mask, the sharpness of the edges of the exposed areas is improved since trapping of unwanted fibres can be prevented.

[0057] A further optional or cumulative technique to improve the quality of the edges of the exposed areas is based on localized depressions created in the mould cover in the areas between the windows defined by a mask (or a plurality of masks). The localized depressions should be limited in dimensions so that they do not constitute a true relieve watermark because too large watermark areas tend to flatten back before the paper formation is set. Accordingly, the pulp is replenished with a pseudo-watermark covering the areas where the strip of foil touches the mould cover outside the mask. In addition, a certain space is freed beneath the strip of foil outside the mask where the strip would otherwise unduly touch the mould cover. This technique is especially suitable for configurations in which the masks (exposed areas defined by the mask/masks) are located so far away from one another that the suspended thread would normally touch against the mould cover surface in between the respective locations. In that case, a zone of disturbance for the paper formation would be created which can be avoided by including the localized depressions in the mould cover. Furthermore, the technique is also useful for mould cover cylinders having comparatively small diameters since then the surface curvature is larger thereby establishing a higher risk of contact between the substrate (thread) and the mould cover.

[0058] In some configurations, the edges of the exposed areas (windows) on the reverse side of the substrate are badly contoured such that some perforations of the strip of foil are exposed open within the finished document. This type of defect is obvious in cases of a bad registration of the strip of foil (lateral or vertical) with the substrate or in case of plain wrong (too large) sizes of a mask applied to the mould cylinder for establishing the exposed areas (windows). The latter represents a systematic defect. However, in some instances this defect could also be visible on perfectly registered and appropriately sized masks, namely, if a too harsh cleaning technique (application of a fluidic jet) is applied to the reverse side of the strip of foil. Thereby, wet paper could be washed off such that fibres are displaced from the reverse side to the front side through the perforations (so-called "over-spraying"). Of course, omitting the cleaning technique might also be problematic since cleaning might be necessary to counteract the opposite phenomenon of excess fibres contaminating the exposed area (window) on the reverse side. Therefore, an approach to avoid this defect is presented herein below.

[0059] According to a further optional or cumulative aspect, the valuable document can be a banknote. In this case a minimum paper weight of 80 g/sqm is used for the banknote paper overall. For a two-layer configuration including a mould (cover) layer and a short former layer, the mould cover layer can be kept significantly thicker than the short former layer, at least at locations where this latter is present. Thereby, accidental fibres displacement back-through-front (from the reverse surface of the substrate through perforations within the strip of foil towards the front side of the substrate) which could immediately lead to surrounding and worsening the quality of the exposed area (window) can be counteracted. The reason is given by the enlarged thickness of the mould cover layer which leads to a decrease of the risk of accidental fiber displacement through the substrate.

[0060] In order to avoid that fibres are deposited onto the window areas on the reverse side, usually an active cleaning (repulsion) technique is applied, such as the application of a fluidic jet (water, air or a mixture of fluids) by at least one nozzle directed towards the reverse side. Preferably, the overall jet can be operated with synchronized pulsed nozzles that swipe a slightly wider and longer area than the area of the exposed area (window) of the strip of foil. This means that the area of the exposed area (first area) is smaller in size compared to the area onto which the fluidic jet is applied (second area). Preferably, the second area should have dimensions such that the second area extends to locations between the area of the exposed area (window) and the area in which perforations within the strip of foil are arranged. Since in areas of the exposed area (window) no glue is applied and since the perforations are completely surrounded by glue, the edges of the second area are preferably located (the second area extends) between the no-glue zone and the glued zone. In other words, the second area preferably extends towards the glue transition area. Generally, the size of the glue transition area is between 0.3mm and 0.6mm in length and width. However, the size of the glue transition area usually depends on the design of the valuable document. The intensity of the fluidic jet can be adjusted such that no wet paper is washed off and such that no fibres are washed through the perforations towards the front side of the substrate.

[0061] Taking into account the size of the glue transition size of usually about 0.3mm to 0.6mm, a further challenge arises since no (or only very few) commercial nozzles are available with regard to these dimensions. This means, there appears to be no commercially available nozzle, which shows sufficient appropriateness to ensure a corresponding contouring of the fluidic jet (pulsed jet) at the production speed of the paper substrate. Therefore, some minor, occasional inevitable defects may occur on the reverse side of the substrate and, so far, are tolerated. This effect can be at least visually masked. A visual compensation of the less-defined contour of the exposed areas (windows) on the reverse side of the substrate may result from the sharp mask-made contour on the front side. The front side exposed area is slightly smaller in size compared to the reverse side exposed area. In case a user looks at the exposed area on the reverse side against a light source or at least against sufficient brightness, and in case the strip of foil is at least partially transparent, the user in fact always sees the sharply edged shape of the front window, also in transmitted light on the reverse side. In other words, the transparency of the strip of foil may enable the sharp (well-defined) edges of the exposed area on the front side of the substrate to shine through the strip of foil such that the user may have the visual impression that the edges of the exposed area on the reverse side of the substrate are sharp (well-defined) as well. The visual compensation for the imperfect edges under incident (direct) light on the reverse side, instead, may normally be masked out if a high coverage print in register over the paper (on the reverse side) is used. This is very forgiving as to the borders imperfection.

[0062] For two-layer configurations, a groove watermark may be included via the short former layer and juxtaposed to the mould cover layer in register with the strip of foil on the reverse side of the substrate. The groove watermark may then comprise a width (size) that exactly corresponds to the width (size) of the wanted exposed area (window area). Preferably, the groove watermark is positioned at the reverse side of the substrate at an area corresponding to the exposed area (window area) on the front side of the substrate. In other words, the groove watermark is positioned such that it appears on the front side of the substrate at locations representing an ideal registration between the groove watermark and the exposed area of the front side. In an alternative, the groove watermark may also be slightly narrower (smaller in size) compared to the exposed area on the front side of the substrate. However, in any case, the groove watermark is not narrower (smaller in size) than the glue edges of the exposed area on the reverse side. This configuration is particularly beneficial in case of elongated exposed areas (rectangular shapes having differently sized edge lengths). The longer edges are dimensionally much more relevant than the comparatively short top and bottom edges of the window. Therefore, the longer side edges become more salient to the eye of the user eliminating the vast majority of the minor imperfections on the window edges on the reverse side of the substrate. Accordingly, only the occasional imperfections at the top and bottom edges of the exposed areas (window areas) on the reverse side are left. However, due to the decreased length, these are less noticeable. In this case, the document printed design constrain is only localized at the comparatively short top and bottom edges on the reverse side of the substrate. If desired, the comparatively short edges could also be thoroughly dissimulated by a high coverage overprint, thereby masking the occasional imperfections. This aspect could also be combined with the pseudo-watermark technique mentioned herein before. Thanks to the localized mould cover depressions the disruptive effect of "over-spraying" at the reverse side can be significantly reduced or limited. This means that for the special case of elongated exposed areas the visual appearance of occasional disturbances can be improved at least for the longer side edges of the exposed areas on the reverse side of the substrate by one or a combination of the described approaches.

[0063] According to a further optional or cumulative aspect, a different approach relies on achieving a well-defined contoured exposed area (window area) on the reverse side of the substrate by means of a (super-)hydrophobic transparent and flexible coating. Such coating may be printed on the strip of foil at the foil manufacturing site. It could also be labile. So, after establishing the exposed area (window) the coating could be deactivated or worn off. In this regard, a solution having an appropriate pH value may be used. Other techniques to deactivate the effect relate to the application of elevated temperatures, strong light sources, applying light sources that emit light of appropriate wave lengths, or simply due to degradation over time. Of course, the coating could also permanently persist in place. Preferably, if the coating persists, the coating should be substantially (or fully) transparent for the naked human eye. Moreover, the coating preferably is flexible as otherwise usability of the document would is degraded. Furthermore, the coating should be of a type, which does not damage, stain or weaken the material of the strip of foil. The coating should also be of a type not hampering overprinting of the exposed area of the document if desired. In any case, extended durability of the coating is not essential as the coating has fulfilled its function after the paper making process finished. The application of a (super-)hydrophobic coating also allows more elaborate shapes of the exposed area to be achieved. Accordingly, shapes beyond the basic geometries like circles, rectangles, ovals may be chosen, such as, e.g., a star, a clover, etc.. In this case, the short former layer may be applied just wider (larger in size) than the so formed exposed area (window).

[0064] Generally, as to the perforations, the perforated strip of foil is not necessarily dimensionally stable upon the application of forces during the registration process. In other words, given the perforations, the strip of foil may generally elongate and/or retract under certain pull and release conditions since the perforations may alter in shape upon the application of forces. In contrast, the carrier material of the strip of foil is usually intrinsically elastic under those forces. Dimensional instability may generally cause unwanted positions of the perforations as well as unwanted haptic effects. In order to avoid a misalignment (non-optimized registration) and to maintain the dimensional stability of the strip of foil all over, the foils perforation can be patterned such that the strip of foil comprises at least one, fully non-perforated stretch (section) along its entire length in addition to the continuous side edges of the strip of foil themselves. In other words, the strip of foil may comprise a stretch (section) within the strip of foil along the unwinding/insertion direction during the registration process so that a gentle pull/release does not result in any inelastic deformation. Accordingly, dimensional stability of the strip of foil may be ensured during the registration process based on the cooperation of the side edges as well as the non-perforated stretch (section) of the strip.

[0065] According to a further or cumulative aspect, a poor contouring of the exposed area (window) on the reverse side of the substrate may be counteracted based on a specific perforation-related property of at least some of the perforations of the strip of foil. The perforations arranged just around the exposed area of the strip of foil may comprise a first shape and perforations which are located farther away from the exposed area may comprise a second shape. The first shape may be different from the second shape. In particular, the first shape may be smaller or larger in at least one dimension. Also, the shape per se may be different, such as circles vs. squares. In an alternative, the first and the second shapes of the respective perforations may also be similar to each other. In this case, a spacing (mean average distance) between the perforations arranged just around the exposed area may be different from a spacing between perforations being located farther away from the exposed area. In other words, the perforations arranged just around the exposed area may be differently designed compared to the remaining perforations. Preferably, from the viewpoint of the exposed area at maximum two neighboring rows of perforations included in the strip of foil are altered in this way. Although there are deviations present within the pattern of the perforations or differences present with regard to the perforations themselves, the dimensional stability of the strip of foil may remain unaffected. This may be achieved as long as such sparse, singular oddities of the perforation pattern or the perforations themselves are not located within the contiguity of the fully non-perforated stretch (section) of the strip of foil. Such an adapted morphology of the perforations in the vicinity (periphery) of the edges of the exposed area (window) favors the correct formation of the edges of the exposed area. Adapted morphology refers to a larger locally averaged open area of the perforations where there is excess of fibres that need to be displaced to free the exposed area or a narrower area where there is a higher risk of depletion through washing off by the water flow or the fluidic jet applied by nozzles. Also, this refers to a tighter hole arrangement where the geometry of the exposed area would create too much space between two contiguous holes on a regular pattern. The adapted morphology is particularly advantageous if a groove watermark within the short former layer cannot be invoked to cover up the imperfections described herein before.

[0066] The above mentioned aspects can be singly or cumulatively applied to the valuable document. Accordingly an embedded strip of foil can be achieved showing high quality. In other words, the exposed area may show sharp edges on the front side of the substrate as well as on the reverse side at least if one or several of the techniques described above are applied.

[0067] Further aspects and characteristics of the invention will ensue from the following description of preferred embodiments of the invention with reference to the accompanying drawings, wherein

• Fig. 1 is a simplified representation of a valuable document according to an embodiment;
• Fig. 2 is a cross sectional view of a cut along line A-A through the valuable document of Fig. 1;
• Fig. 3 is a cross sectional view of a cut along line A-A through the valuable document of Fig. 1 according to another embodiment;
• Fig. 4 is a cross sectional view of a cut along line A-A through the valuable document of Fig. 1 according to an additional embodiment;
• Fig. 5 is a cross sectional view of a cut along line A-A through the valuable document of Fig. 1 according to another embodiment;
• Fig. 6 is a simplified representation of a valuable document according to another embodiment;
• Fig. 7 is a cross sectional view of a cut along line B-B through the valuable document of Fig. 6;
• Fig. 8 is a cross sectional view of a cut along line B-B through the valuable document of Fig. 6 according to another embodiment;
• Fig. 9 is a simplified representation of a valuable document according to an additional embodiment,
• Fig. 10 is a cross sectional view of a cut along line C-C through the valuable document of Fig. 9;
• Fig. 11 is another cross sectional view of a cut along line C-C through the valuable document of Fig. 9 according to another embodiment; and
• Fig. 12 is a simplified representation of a mould for manufacturing a valuable document according to an embodiment.

[0068] All of the features disclosed hereinafter with respect to the example embodiments and/or the accompanying figures can alone or in any subcombination be combined with features of the aspects of the present invention including features of preferred embodiments thereof, provided the resulting feature combination is reasonable to a person skilled in the art.

[0069] Fig. 1 is a simplified representation of a valuable document 10 according to an embodiment. The valuable document 10 comprises the strip of foil 30 which is embedded in the thickness of the paper web also referred to as paper substrate, fibrous material, or fiber substrate 20. The strip of foil 30 comprises perforations 31. Although shown in this representation, the perforations 31 are covered by fibers of the fiber substrate 20. The perforations 31 are advantageously arranged in parallel rows and columns consisting of homogeneously arranged perforations 31. Thereby, the perforations form a pattern 40. A line A-A indicates a virtual cut for the cross sectional views of Figs. 2 to 5.

[0070] The perforation 31 has a first width W1 in a first direction. In the first direction, the elongate strip of foil 30 has a second width W2. The first width W1 of the perforation 31 is smaller than the second width W2 of the strip of foil. In an alternative, the width of the perforation 31 may be determined in a second direction perpendicular to the first direction. Then, the width of the perforation 31 may be compared to a third width W3 of the valuable document 10 along the second direction.

[0071] Fig. 2 is a cross sectional view of a cut along line A-A through the valuable document 10 of Fig. 1. The strip of foil 30 is covered by fibers that protrude through the perforations/holes/openings 31 and thereby secure the strip of foil 30 and also accumulate on both sides of the strip of foil. The strip of foil 31 is embedded in the thickness of the fiber substrate 20. The shown configuration relates to monolayer substrate. The valuable document 10 comprises a homogeneous thickness T having two parallel surfaces 21, 22 of the fiber substrate 20. Accordingly, the haptic effect is based on a property difference relating to at least one of a bending coefficient, a hardness, a flexibility, and a pressure sensitivity. The strip of foil 30 may comprise properties being different of that of a remainder of the valuable document 10. Accordingly, based on the perforations the property difference may be recognizable by a user since the user may "feel" a different behavior in perforated regions compared to non-perforated regions. Based on the size of the perforations 31 this effect may relate to pattern-based regions of the perforations 31 or to the single perforations 31 themselves. In other words, the property difference may be recognizable for each location at which a perforation is arranged independently. In an alternative, the user recognizes a property difference since the pattern 40 of perforations 31 as a whole establishes a difference with regard to a specific property compared to regions of the document 10 not comprising any perforations 31.

[0072] Fig. 3 is a cross sectional view of a cut along line A-A through the valuable document 10 of Fig. 1 according to another embodiment. In this case, the valuable document 10 comprises a non-constant thickness. The document 10 comprises a second thickness T2 at a location outside the strip of foil 30 at a non-perforated region. At the location of a perforation 31 the valuable document 10 comprises a first minimum thickness T1 at dips 23 between the first and second surfaces 21, 22 of the fiber substrate 20. The first thickness T1 is less than the second thickness T1. Based on the thickness variation, a user may recognize the perforations 31 of the embedded strip of foil 30 on tactile or haptic basis.

[0073] Fig. 4 is a cross sectional view of a cut along line A-A through the valuable document 10 of Fig. 1 according to yet another embodiment. In this embodiment, fibers of the fiber substrate 20 are accumulated during the production process and form bumps on both sides of the embedded strip of foil 30. The height HB indicates the height of accumulated fibers, i.e. the height by which the accumulated fibers (or the bump) extend over the (normal) surface (in this case horizontal surface) of the substrate having no accumulated fibers.

[0074] Just as an option, the fiber substrate 20 can have a double layer configuration including a short former layer 35 and a mould layer 36. This configuration is shown in Fig. 5 according to a cross sectional view of a cut along line A-A through the valuable document 10 of Fig. 1 according to yet another embodiment.. The short former layer 35 would then subsequently be placed on top of the mould layer 36. However, the strip of foil 30 is still integrated or embedded in the mould layer 36. The short former layer does not cover the area G. In other words, the short former layer 35 comprises a depletion zone G in which it is absent. The depletion zone G is at least partially in register with the embedded strip of foil 30. In an embodiment, the short former layer 35 may overlap the edges of the embedded strip of foil 30 to a certain extent. In comparison with the embodiment shown in Fig. 4, the height HB of the accumulated fibers or the bump can be lower than the height HB in a monolayer configuration as shown in Fig. 4. However, also a single layer configuration can be used for the fiber substrate 20.

[0075] Fig. 6 is a simplified representation of a valuable document 10 according to another embodiment. In this embodiment, the distribution and spacing of the perforations 31 is furthermore such that at least a continuous portion of the film (strip of foil 30) is preserved without any perforation 31 interposed within this portion. This assists in maintaining adequate resistance to the strip deformation upon pulling for embedding, for the integrity of the geometry and for registration management. There is further a window area 32 in which the strip of foil 30 is exposed or uncovered. A line B-B is shown indicating a virtual cut for the cross sectional views of Figs. 7 and 8.

[0076] Fig. 7 is a cross sectional view of a cut along line B-B through the valuable document 10 of Fig. 6. This cross sectional view shows a virtual cut through the window area 32. The window area 32 is exposed or uncovered on both - opposite - sides of the valuable document 10. The lateral sides of the strip of foil 30 are embedded in the thickness of the fiber substrate 20 and fibers 33 of the fiber substrate protrude through the perforations/holes/openings 31 on the lateral sides. There are no further perforations/opening/holes within the window area 32 according to this embodiment. The fiber substrate 20 can be a single layer paper substrate. However, also a multi layer configuration can be used. A short former layer 35 may be placed on top of the mould layer 36. The short former layer 35 could then have a depletion zone G, in which the short former layer is absent, horizontally registered with the embedded strip of foil 30 in register with the window area 32.

[0077] Fig. 8 is a cross sectional view of a cut along line B-B through the valuable document 10 of Fig. 6 according to another embodiment. In this embodiment, the window area 32 is formed by a strip of foil 30 made of a transparent material. However, additional perforations 31 are arranged in the window area 32, in which no material is located at all. Therefore, the perforations 31 may be simple to be recognized, at least in the window area 32.

[0078] Fig. 9 is a simplified representation of a valuable document 10 according to another embodiment. As described with respect to Fig. 6, the strip of foil 30 is embedded in the thickness of the substrate 31. The main difference with respect to the embodiment of Fig. 6 consists in the shape of the window are 32, which is different from previous embodiments. Moreover, only a single opening 34 is arranged in the window area 32 which becomes apparent from the cross sectional view along line C-C shown in Fig. 10.

[0079] Fig. 10 is a cross sectional view of a cut along line C-C through the valuable document of Fig. 9. The window area 32 comprises a perforation/through hole/opening 34. The lateral sides of the strip of foil 30 are embedded into the thickness of the fiber substrate 20. Fibers 33 of the fiber substrate 20 protrude through these perforations/holes/openings 31. Furthermore, the window area 32 is only directed to one side and covered on the opposite side by fibers 33. In this embodiment, but also in any other embodiment, it is generally possible to expose the window area 32 of the strip of foil 30 to either one side of the valuable document 10 or to both sides of the valuable document 10. The fibers 33 may even extend over the top surface of the window area on the side on which the window area 32 is mainly exposed. This provides the possibility to create additional optical, haptic, tactile or other effects thereby improving security. Also in a two or multi layer configuration of the fiber substrate 20, this additional configuration can be advantageously used. The elongate strip of foil 30 can comprise at least one opening (perforation) 34 in the area of the window. The fibers 33 of the mould layer 36 can then protrude through the at least one opening 34 towards the side of the short former layer 36. This also provides increased flexibility regarding the creation and properties of security features in the window area 32. In particular, new tactile or haptic effects may be created that cannot easily be copied.

[0080] In the previously described embodiments, a valuable document 10 comprising a fiber substrate 20, in particular paper, is provided. The fiber substrate 20 comprises a registered elongate strip (or band, wide thread) of foil 30 being partially embedded in the thickness of the fiber substrate 20. The elongate strip of foil 30 is at least partially perforated (porous) in order to be permeable for fibers 33 of the fiber substrate 20. The elongate strip of foil 30 is exposed or uncovered in a window area 32 on at least one side of the valuable document 10. The terms "exposed" or "uncovered" mean that the window area 32 is at least partially free or clean of fibers 33 of the fiber substrate 20 so as to provide a window 32 area for a security element of the elongate strip of foil 30 which is in register with the window area 32.

[0081] Fig. 11 is a cross sectional view of a cut along line C-C through the valuable document of Fig. 9 according to another embodiment. The difference with respect to the embodiment shown in Fig. 10 is that the fibers 33 now protrude through the opening 34 in the strip of foil 30 in the opposite direction. This means that in one embodiment, the fibers 33 protrude from the side of the mould layer 36 towards the side of the short former layer 35, while in the embodiment shown in Fig. 11 the fibers 33 protrude from the side of the short former layer 35 towards the side of the mould layer 36. However the fibers 33 which protrude through the opening 34 still belong to the mould layer 36 regardless from which side they protrude through the opening 34.

[0082] Fig. 12 is a simplified representation of a paper mould for manufacturing a valuable document 10 according to an embodiment. There is a first cylinder 50 and some other cylinders, only one of which is shown as a second cylinder 52. The elongate registered strip of foil 53 is fed to the first cylinder 50. The pulp 54 surrounds the first cylinder partially. The first cylinder 50 is made of a mesh of wires such that the pulp 54 tends to flow towards the mesh of the first cylinder 50. The fibers in the pulp 54 are held back by the mesh of wires on the first cylinder 50 and deposit on the outside of the first cylinder 50 thereby creating a paper web 55. An at least partially porous or perforated strip of foil 53 allows the fibers to extend through the openings (not visible here). Areas free of fiber can either be created by covering specific points, areas, or locations etc. on the wire mesh of the first cylinder. This is roughly indicated by elements 56 which may merely plug some or all openings in the wire mesh of the first cylinder 50. This locally prevents the pulp 55 from draining towards the inside of the first cylinder 50 such that in those selectively chosen locations, no or less fibers accumulate. Furthermore, the elements 56 also touch the surface of the elongate strip of foil 53 thereby preventing the fibers still flowing in the turbulent pulp mass to enter in contact with the surface of the strip of foil 53 at this location (the location of the elements 56). The results can be locally thinner areas (watermarking), openings or holes in the paper web 55. The same principle applies to the strip of foil 53. If the strip of foil is locally impermeable for the liquid in the pulp, this also prevents the fibers from depositing outside the strip of foil 53 in those impermeable areas or at least reduces the amount of fibers that accumulate in those areas.

[0083] The main disadvantage of known techniques of watermarking as previously described is the poor quality of the window areas. The borders of the window areas are not sharp enough and some fibers always remain within in the window area and on the strip of foil 53 in those areas.

[0084] In order to improve the quality of the windows or window areas, at least one nozzle 57 (but usually more in a row) is provided that is configured to clean the window area from the remaining fibers and to sharpen the borders of the window. Through the nozzle 57, a fluid 58, as for example water or air or a mixture of water and air is supplied to the surface of the window area. This removes remaining fibers and cleans the window. Furthermore, the borders of the window area can become sharper. In other words, the exposed or uncovered area (window area) is generated by selective local repulsion of fibers and, in this embodiment, the local repulsion is induced by application of a fluid 58, advantageously in form of a jet through the nozzle 57. The fluid can be compressed air and/or water.

[0085] In other, more general words, an at least partially porous or perforated strip of foil 53 can be provided in a paper mould 54 around a first cylinder 50. The first cylinder 50 partially resides in the pulp 54. A paper web 55 is generated from the pulp 54 on an outer wall of the first cylinder 50 by rotating the first cylinder 50. The pulp 54 is dewatered through a permeable outer wall (wire mesh) of the first cylinder 50. During these steps, the strip of foil 53 is kept in register with the paper web 54, and fibers of the pulp 54/paper web 55 are actively removed from a window area of the strip of foil 53.

[0086] In one embodiment, the removal of the fibers can be performed by the previously described nozzle 57 and a fluid 58 supplied from the nozzle 57. The fluid 58 from the nozzle 57 can be applied continuously and/or pulse-wise in pulses of adjustable duration and/or synchronized in relation to the target position of the window.

[0087] The nozzle 57 (or a plurality of nozzles 57) can advantageously be a conic stream nozzle. In case the fluid is water, the water pressure may be 0 to 10 bar, advantageously 0.2 to 3 bar and the distance from the mould can be from 2 cm to 25 cm, conveniently from 4 cm to 18 cm from the mould cover surface. In case the fluid is air/ compressed air, the pressure may be 0 to 10 bar, advantageously 0.2 to 3 bar and the distance from the mould can be 2 cm to 25 cm, advantageously 4 cm to 18 cm.

[0088] The speed of the first cylinder 50 may need to sustain variations to comply with production/quality needs. It is therefore necessary that the devised system for the creation of windows on the substrate in order to reveal the embedded strip of foil 53 is

a) as a minimum, tolerant to speed variations of +/ - 10 m/ min and/ or

b) configured to be adjusted to the speed variations to optimize the performance even beyond the speed limits indicated above.

[0089] The adaptive capability should include:

1) variation of frequency of opening and closing of the valve(s) used to manage machine speed variations, but also necessary to tune the spraying time and pace in case of multiple windows per notes, of different banknote dimensions (i.e. windows spacing may vary), windows with different shapes (i.e. differently elongated windows),

2) variations of the orientation angle of the nozzle(s) (with chances of rotation speed of the mould cover, the impact angle of the jets need to vary to preserve the shape and cleanness of the window),

3) distance of the nozzle 57 to the surface,

4) controlled variation of the spraying pressure and

5) controlled variation of the sprayed fluid composition and besides that,

6) the capability of the nozzle 57 to stay relatively clean in very turbulent environments at high speed to prevent fibers encrusting over its surface that could introduce defects on the paper (self-cleaning).

[0090] In an aspect of the invention, the amount of fibers (density) can be increased and then the pressure of the jet of fluid can be increased. This reduces the risk that the paper web 55 is negatively affected. The pulp density at the cleaning point (lead by pulp consistency at inlet and drainage and wet-end chemistry driven) needs to be adjusted to allow the fibers to be removed. This is due to the fact that too dry pulp could be resistant to removal, as well as too diluted pulp could "reform" and cover the window again right after the cleaning action.

[0091] In still another aspect of the invention, the position of the window areas 32 on the strip of foil and the respective positions of elements 56 are optimized.

[0092] The maximum possible distance between the protruding elements 56 (for example in the shape of coins) is dependant on the mould cover diameter. It is essential that the inserted strip of foil 53 is never tangent to the mould cover surface, which happens when two elements 56 are too far spaced away from each other. A defect could be introduced at the tangent point for the strip of foil 53 and paper formation may be disturbed. In order to prevent this effect, it might be necessary to introduce extra elements 56, the function of which is not to open a window but just to support the strip of foil 53 in its way around the mould cover without touching the mesh. Typically this is often necessary at the junction of two consecutive banknote sheets as the gap between two banknotes and therefore two secure windows happens to be longer due to the sheet edges that are normally cut out during the banknote finishing process. Paper machines with a mould of smaller diameter are more prone to this event due to geometrical reasons.

[0093] The uncovered area or exposed area of the window can at least partially be generated by locally selective inhibition of substrate formation on the elongate strip of foil 53. The locally selective inhibition can be physically and/or chemically induced. The locally selective inhibition can be induced by local surface treatment of the elongate strip of foil 53. The locally selective inhibition can be provided by a hydrophobic or super-hydrophobic layer/structure. If a super-hydrophobic layer is used, the water droplet/solid surface snap-in forces - measured e.g. using the micro balance in a tensiometer - become zero because the surface tension of the water, hence its internal cohesion, is stronger than the reference surface wettability. Another way to define super-hydrophobic is that the advancing angle of the droplet on a reference surface (not its static angle) is greater than 145° when the liquid is water.

[0094] Super-hydrophobic coatings could be based on, consist of or comprise at least one out of the following components:

• Manganese oxide polystyrene (MnO2/PS) nano-composite,
• Zinc oxide polystyrene (ZnO/PS) nano-composite,
• Precipitated calcium carbonate,
• Carbon nano-tube structures,
• Silica nano-coating,
• Cyclopentasiloxane or similar
• functionalized poly acryl amides, or
• from biological sources, or
• could be generated by applying a physical nano-structure (lotus effect) where conveniently spaced "nano-pillars" of pseudoconical shape or fractal-like shape are introduced.

[0095] A particularly advantageous type of hydrophobic coating should be at least partially transparent or better fully transparent.

[0096] In another embodiment, the exposed or uncovered area can be generated by removal of fibers by suction, in particular discontinuous suction.

[0097] In still another embodiment, some additional fibers can be arranged or locally accumulated in off-limit zones in order to compensate fiber depletion on vicinal areas of the window.

[0098] Furthermore, residual fibers can be removed by a rotating brush. Still further, areas of accumulated fibers can also be evened up by the rotating brush.

[0099] In another embodiment, the fiber substrate 20 can comprise two layers, a mould layer 36 and a short former layer 35 and the elongate strip of foil 53 can be embedded in the mould layer 36. The short former layer 35 can be absent in a depletion zone G at least partially being registered with the strip of foil 30 and/or the window area 32 thereof.

[0100] The window should at least horizontally (in a first direction) be in register with the elongate strip of foil 53. However, it is preferable that the strip of foil 53 is completely in register with the paper web and all layers of the paper web (for example mould layer 36 and short former layer 35). In register means that the relative positions of paper web 55, strip of foil 53, exposed areas (or uncovered areas and respective window areas and security elements in the window areas 32 are all as precise and reliable as possible.

[0101] The mutual registration (tolerance) of the window areas with respect to the substrate in vertical and horizontal (in the direction of the width and the length of the banknote) should have a minimum of about 2.5 mm in each direction, advantageously 1.5 mm in each direction, and more advantageously 1.0 mm in each direction.

[0102] The elongate strip of foil 53 can be transparent or semi-transparent at least in the window area 32 such that fibers of the mould layer 36 are visible through the window from the side of the short former layer 35.

[0103] Although the invention has been described hereinabove with reference to specific embodiments, it is not limited to these embodiments and no doubt further alternatives will occur to the skilled person that lie within the scope of the invention as claimed.

Claims

1. A valuable document (10) comprising a fiber substrate (20) having a front side, a reverse side, and a thickness (T) between the front and the reverse side, the fiber substrate comprising an elongate strip of foil (30) embedded in the thickness of the fiber substrate, the elongate strip of foil comprising at least one perforation (31), the perforation being permeable for and covered by fibers (33) of the fiber substrate, characterized in that the perforation is configured to provide a haptic effect on the front and/or reverse side of the fiber substrate.

2. The valuable document (10) according to claim 1, wherein the valuable document comprises a first thickness (T1) between the front and reverse side in a perforated region of the elongate strip of foil (30) and a different second thickness (T2) between the front and reverse side in a non-perforated region of the elongate strip of foil.

3. The valuable document (10) according to claim 1 or 2, wherein the elongate strip of foil (30) differs in one, two, three or more properties from a remainder of the valuable document, wherein the one or more properties is/are selected from a group consisting of a bending coefficient, a hardness, a flexibility, and a pressure sensitivity, and wherein the haptic effect is based on a property difference of the one, two, three or more properties.

4. The valuable document (10) according to any of the preceding claims, wherein the at least one perforation (31) has a geometric shape, the geometric shape comprising at least one out of a circle, a rectangle, a square, an ellipse, a trapeze, a diamond, a rhombus, and a parallelogram.

5. The valuable document (10) according to any of the preceding claims, wherein the at least one perforation (31) comprises a first width (W1) in a first direction, and the elongate strip of foil (30) comprises a second width (W2) in the first direction, the first width of the perforation being equal to or more than 5% of the second width of the elongate strip of foil in the first direction, preferably the first width being equal to or more than 10% of the second width of the elongate strip of foil in the first direction and at the same time being equal or less than 50% of the area of the strip of foil.

6. The valuable document (10) according to any of the preceding claims, wherein the elongate strip of foil (30) comprises a plurality of perforations (31), wherein the plurality of perforations comprise a combined open area relative to the area of the strip of foil, wherein the combined open area is the sum of all singles areas formed by the independent perforations of the plurality of perforations, wherein the combined open area may be equal to or more than 1% of the area of the strip of foil, preferably equal to or more than 3% of the area of the strip of foil, more preferably equal to or more than 10% of the area of the strip of foil and at the same time being equal or less than 50% of the area of the strip of foil.

7. The valuable document (10) according to claim 6, wherein the plurality of perforations (31) forms a geometric pattern (40).

8. The valuable document (10) according to claim 7, wherein the geometric pattern (40) comprises columns and/or rows at least partially comprising regularly arranged perforations (31).

9. The valuable document (10) according to any of the preceding claims, wherein the material of the elongate strip of foil (30) comprises or consists of one or more materials selected from a group consisting of polyamide, polyethylene, and polyester.

10. The valuable document (10) of any of the preceding claims, wherein the haptic effect is machine readable.

11. The valuable document (10) according to any of the preceding claims, wherein the elongate strip of foil (30) is uncovered or substantially uncovered by fibers (33) of the fiber substrate (20) forming an exposed area of the elongate strip of foil on the front and/or the reverse side of the valuable document, wherein the exposed area forms a window area (32) of the valuable document (10) comprising the elongate strip of foil which is in register with the window area and which optionally comprises in the exposed area one or more security elements selected from a group consisting of optical security element, luminescent security element, including a fluorescent, a phosphorescent and an electroluminescent security element, a magnetic security element.

12. The valuable document (10) according to claim 11, wherein the elongate strip of foil (30) comprises no or at least one perforation (31) arranged in the exposed area.

13. The valuable document (10) according to any of claims 11 to 12, wherein the exposed area is obtainable by selective local repulsion of fibers (33), the local repulsion being induced by application of a fluid (58), in particular compressed air and/or water.

14. The valuable document (10) according to claim 13, wherein the fluid (58) is applied continuously and/or pulse-wise in pulses of adjustable duration and/or synchronized in relation to a target position of the window area (32).

15. The valuable document (10) according to any of the preceding claims, wherein the fiber substrate (20) comprises a mould layer (36) and a short former layer (35) and the elongate strip of foil (30) is embedded in the mould layer.

16. The valuable document (10) according to claim 15, wherein the elongate strip of foil (30) is uncovered or substantially uncovered by fibers (33) of the short former layer (35) forming a window area (32) and the elongate strip of foil (30) is transparent or semi-transparent at least in the window area (32) such that fibers (33) of the mould layer (36) are visible through the window area (32) from the side of the short former layer (35).

Drawing