EP4048526A1

EP4048526A1 - Security element having machine-readable ir code

Info

Publication number: EP4048526A1
Application number: EP20797025.2A
Authority: EP
Inventors: Stefan Bichlmeier; Matthias Pfeiffer; Gerhard HAMPP
Original assignee: Giesecke and Devrient Currency Technology GmbH
Current assignee: Giesecke and Devrient Currency Technology GmbH
Priority date: 2019-10-24
Filing date: 2020-10-16
Publication date: 2022-08-31
Anticipated expiration: 2040-10-16
Also published as: US20240083190A1; US12128703B2; EP4048526B1; DE102019007417A1; CN114555380B; WO2021078406A1; CN114555380A

Abstract

The invention relates to a security element having an optically variable security feature and a machine-readable security feature, which are arranged at least partially one above the other, the security element being transparent or translucent in the visible light spectrum and the machine-readable security element forming a code. The machine-readable security feature is a combination of at least two different substances, a first IR substance and a second IR substance, the first IR substance being arranged in a first area of the security element and the second IR substance being arranged in a second area of the security element, and wherein the first IR substance absorbs in a first IR wavelength range and the second IR substance absorbs in a second IR wavelength range. The invention also relates to a value document having such a security element.

Description

Security element with machine-readable IR code The invention relates to a security element with an optically variable security feature and a machine-readable security feature, which are arranged one above the other, the security element being transparent or translucent in the area of visible light at least in partial areas and the machine-readable security feature forming a code, as well as a value document which has the security element.

Documents of value are equipped with security elements that allow the authenticity of the document of value to be checked and serve as protection against forgery. Documents of value include, in particular, banknotes, shares, identification documents, credit cards, certificates,

Understand insurance cards and documents in general at risk of forgery, for example also product security elements such as labels and packaging for high-quality products. The term "document of value" as used herein includes not only finished, fit documents of value, but also preliminary stages of documents of value such as security papers that do not have all the features of a document of value that is fit for circulation, for example also security papers in sheet or roll form Generally the shape of threads, strips or patches which are applied to a value document or at least partially introduced into a value document, such as window security threads and pendulum security threads, or which are used to cover through openings in a value document. Security elements can also represent a value document themselves , for example a polymer banknote. Security elements have one or more security features, ie components with properties that can be checked visually and / or by machine, on the basis of which the authenticity of a document or another object can be determined.

Security features with optically variable properties are of increasing importance, i.e. the appearance of the security feature varies depending on the viewing angle. A movement effect is created when the viewing angle is continuously changed. Optically variable security features are considered to be very forgery-proof, since the movement effects cannot be generated by conventional printing processes and cannot be "copied" when a security element is photocopied. Examples of optically variable security features are micro-optical security features such as moiré magnifiers, holograms and thin-film elements.

The authenticity of documents of value should not only be able to be checked visually, but also by machine. Machine verifiability offers a high level of security and is also mandatory in many cases, for example when processing banknotes. Devices such as automatic counting machines and vending machines must be able to recognize denominations and verify the authenticity of a banknote. Up to now, magnetic security features have typically been used for machine authentication. Magnetic materials, however, have the disadvantage that they have a strong inherent color, which is why they are clearly visible both in incident light and in transmitted light. Therefore, they can change the appearance of other security features affect. In particular in the case of optically variable security features and security features to be viewed in transmitted light, they have a very disruptive effect. On the other hand, materials of other security features, for example metallizations of holograms, can interact with magnetic security features or impair their readability.

There is therefore a need for a security element which has a high degree of security against forgery and which can be checked for authenticity both visually and by machine.

In particular, there is a need for a security element that has both a security feature with optically variable properties and a security feature that forms a machine-readable code.

The optically variable security feature and the machine-readable security feature should not interfere with each other, i.e. neither the visual appearance and the visual effects of the optically variable security feature should be impaired by the machine-readable security feature, nor should the readability of the machine-readable code be visually testable security feature are disrupted.

The invention satisfies this need by means of a machine-readable security feature that forms a code with the aid of at least two IR subsets which are different from one another and which are arranged in the security element in a defined manner. Two different IR substances are to be understood as meaning two substances which absorb in different IR wavelength ranges. The present invention provides a security element with an optically variable security feature and a machine-readable security feature, which are at least partially arranged one above the other, the security element being transparent or translucent for wavelengths of visible light at least in the area in which the optically variable security feature is located and the machine-readable security feature forms a code. At least in the area in which the machine-readable security feature is located, the security element must be sufficiently transparent for the respective IR

Be radiation wavelength in order to ensure the readability of the machine-readable security feature. The machine-readable security feature is a combination of a first IR substance, i.e. a substance which absorbs in a first IR wavelength range, and a second IR substance, i.e. a substance which absorbs in a second IR wavelength range. The first IR wavelength range and the second IR wavelength range are different from one another and can be distinguished by machine. The first IR substance is located in a first surface area of the security element, and the second IR substance is located in a second surface area of the security element, the first surface area and the second surface area not being identical. The surface areas can each be subdivided into partial areas, it being possible for both first IR substance and second IR substance to be located in individual partial areas.

The distinction between a first and a second IR substance, a first and a second IR wavelength range, and a first and a second area range is arbitrary and in the sense of "an" or

to understand "another". Likewise, terms such as “a” and “an” are to be understood in the sense of “at least one” or “at least one”. A security element is considered to be transparent to visible light if a viewer can see what is behind the security element. Security elements or areas of security elements that allow light to pass through but do not reveal any objects behind are considered to be translucent. The present invention enables multicoding which is achieved through the use of more than one IR substance in combination with arrangement variants of the more than one IR substance.

Each of the at least two IR substances used generates a characteristic IR signature, i.e. an absorption spectrum that can be used to clearly characterize the IR substance in question. For example, the wavelengths of absorption maxima and / or absorption minima, the width of the absorption maxima and / or absorption minima, the slope or the change in the slope of a spectrum, as well as several

Absorption maxima or absorption minima their distance from one another and / or their relative height to one another.

In addition, the at least two IR substances can be distributed in a variety of ways over the surface of the security element and in particular over the area of the security element in which the optically variable security feature is located. Exemplary array _V are ariants a distribution of the IR-substances such is that areas with IR substance and areas without IR substance revealed wherein the areas with IR substance have at least in part different IR substances; a distribution such that the regions with IR substance are separated from one another or overlap one another; a distribution such that each area with an IR substance contains only one IR substance or a mixture of IR substances; a distribution such that the areas with IR substance have different concentrations of IR substance, either within a single area or varying from area to area; as well as a combination of the mentioned arrangement variants. Alternatively or additionally, the IR signature of one or more areas with an IR substance can be changed by measures such as partial or complete overprinting with a non-IR-permeable layer and / or by mixing the IR substance (s) with IR-absorbing substances .

For the purposes of the present invention, suitable IR substances must meet certain requirements.

On the one hand, the combinations of IR substances used must be coordinated with one another in such a way that they can be distinguished from one another by machine. On the other hand, each of the IR substances used should preferably meet a number of requirements. This primarily means that the presence of the IR substance should not interfere with the perceptibility of the optically variable security feature. The IR substances used should therefore be transparent in the visible wavelength range (in the wavelength range from 400 nm to 700 nm). There is sufficient transparency when the CIE (1976) brightness value with diffuse reflection (L *) is higher than 70 (measured on the pure IR substance powder). The value is preferably higher than 80. For reasons of good detectability, it is preferred that the IR substances absorb as strongly as possible in the IR range (in the wavelength range from greater than 700 nm to 2500 nm). Strong absorption in the near infrared range (NIR range), ie in the wavelength range from greater than 700 nm to 1100 nm, is particularly desirable. This range is easily accessible with silicon photodetectors that are sensitive up to a wavelength of 1100 nm.

Furthermore, IR substances with broadband absorption in the IR range are preferred over IR substances with narrowband absorption. The reason for this is that there is no IR color standard in the IR range that is comparable to the CIELAB standard. Therefore, the values that are measured with different detectors for a specific absorption of an IR substance can vary. The deviations are not significant in the case of rather broadband absorptions, but are noticeable in the case of very narrowband absorptions and could lead to an incorrect evaluation of the measured values measured with different detectors.

Examples of suitable IR substances are given in the publication WO2007 / 060133 A1. Particularly suitable are iron (II) and copper (II) compounds with an Fe2 + ion or a Cu2 + ion in a suitable chemical environment, a suitable chemical environment for example a phosphate ion or a polyphosphate ion or, more generally, a phosphorus and oxygen containing group. These IR substances absorbing broadband in the NIR range (700 nm to 1100 nm) are transparent in the visible range (400 nm to 700 nm) of the electromagnetic spectrum, whereby they have at most a slightly yellowish or bluish tint. Pigments of the printing inks sold by the company SICPA (SICPA SA, Ave de Florian 41, 1008 Prilly, Switzerland) under the trade name SICPATALK are particularly preferred. These printing inks have been found to be particularly well suited for the purposes of the present invention. SICPATALK® CBA and SICPATALK® NFB have proven to be particularly suitable, both of which are almost colorless and therefore essentially invisible to an observer. LUMOGEN-S from BASF Corporation, 100 Park Ave., Florham Park, NJ 07932, the IR-absorbing materials disclosed in GB 2168372, which are invisible or transparent in the visible range of the electromagnetic spectrum, can be named as further suitable IR substances, and the IR markers disclosed in US 6,926,764. These IR markers are substituted

Phthalocyanines, naphthalocyanines, metal-containing phthalocyanines or poly-substituted phthalocyanines. Thiophenol-substituted copper phthalocyanines, in particular para-toluene thiol-persubstituted copper phthalocyanines, are preferred.

The type of application of the IR substances is in principle not restricted in any way, but is preferably carried out through formulation as printing inks, the inks being particularly preferably applied using the intaglio printing process. The intaglio printing process has the advantage that inks with a high solids content can be used. This allows the use of IR substances which have only weak IR absorptions in the desired range, since they can be used in high concentration and thus generate sufficiently strong signals. Suitable concentrations of IR substance are in the range from 5 to 70% by weight, preferably 10 to 50% by weight, and particularly preferably 20 to 50% by weight, based on the weight of the ink as a whole. In addition, the usual printing ink Bes found parts, in particular intaglio printing ink components, which are known to a person skilled in the art, can be used.

When applying the IR substances using the intaglio printing process, care should be taken that the average particle size does not exceed 50 μm, preferably 20 μm, and particularly preferably 10 μm. There should not be any particles with a size of more than 100 μm, since such particles can be wiped out of the engraving of the printing plate. The fiction like ate multicoding using at least two different IR substances (substances that absorb in the IR range, but at different wavelengths or in different wavelength ranges) can in principle be applied to any type of security element that is used in the relevant IR Wavelength range are sufficiently transparent to allow detection of the IR substances, but it is particularly advantageous in those security elements in which visually clearly perceptible substances, such as strongly colored substances and / or magnetic substances cannot be used. These are in particular security elements with optically variable security features, including, for example, moiré magnifiers.

Moiré magnifiers are multilayer structures that have a focusing layer such as a lens arrangement, an image layer with an arrangement of picture elements, and typically also include a spacer layer between the lens layer and the image layer. The picture elements are enlarged or optically changed in some other way when viewed through the lenses. Further functional layers and / or auxiliary layers can also be present. The structure, materials and production of security elements with optically variable security features such as lens-based security features are known to a person skilled in the art. In this regard, reference is made to the explanations in the publications WO 2006/087138 A1, EP 2853411 A1, WO 2017/097430 A1 and WO 2018/072881 A2.

Other optically variable security features with which the multicoding according to the invention can be combined particularly advantageously are, for example, holograms and thin-film elements. The multicoding according to the invention can also be advantageously combined with transparent liquid crystal layers.

As a special example, so-called LEAD (Longlasting Economical Anticopy Device) security elements should be mentioned. These security elements have functional layers on a carrier film, such as an embossed lacquer layer with a holographic security feature, metallized layers with colored or fluorescent imprints, layers with motifs recognizable in transmitted light, etc. This functional layer structure also includes auxiliary layers such as pressure acceptance, adhesion promoter or protective layers. LEAD security elements are available as T-LEAD security elements and as L-LEAD security elements. T-LEAD security elements are designed as transfer elements, ie a transfer film is peeled off after the transfer onto the value document. L-LEAD security elements contain at least one im Wavelength range of visible light, transparent film that remains in the security element structure. L-LEAD security elements are preferably used to cover through openings in documents of value.

The multicoding according to the invention is also suitable for use in such multi-layered security elements. It is only necessary to ensure that the IR substances are provided in a layer that is not covered by IR-absorbing materials. In general, it applies to all security elements that have multicoding according to the invention that the materials used in the detection wavelength range of the multicoding must be transparent for the detection wavelengths. A lack of transparency of certain layers for the detection wavelengths can, however, also be used deliberately in order to make certain parts of the code recognizable only under respectively defined conditions. For example, part of the code could only be recognizable when checked on one of the surfaces of a value document, while the other part of the code can only be detected when checked on the other surface of the value document.

Security elements are flat materials. They can have one or more optically variable security features, wherein an optically variable security feature can extend over part of the surface of the security element or over the entire surface of the security element. The same applies to the machine-readable security feature. It also extends over part of the surface or over the entire surface of the security element, the extension region of the machine-readable security feature being referred to below as the “coding region”, during the Extension area of the optically variable security feature is referred to below as “optically variable area”.

The coding area and the optically variable area are arranged in such a way that they at least partially overlap one another when viewed from above on the security element. Alternatively, they can also be arranged completely or at least largely congruently.

In order to achieve the most diverse possible coding variants, the invention provides for the coding area to be structured in different ways. This results in numerous coding options, the number of which can be increased even further through variations in the area of the IR substances and / or the use of further substances or suitable printing techniques in order to further structure individual areas. Some design variants of the coding area are listed below as examples:

One of the IR substances (a first IR substance) is located in a first surface area of the security element and a further IR substance (a second IR substance) is located in a second surface area of the security element, the first surface area and the second surface area are not identical.

The first surface area and / or the second surface area can be divided into partial areas. The first surface area and the second surface area or partial areas thereof can have the same or different dimensions and the same or different geometric shapes.

The first surface area and the second surface area or partial areas thereof can adjoin one another or be spaced apart from one another, in particular be separated from one another by areas without an IR substance.

Subareas of the first surface area and the second surface area can be arranged strictly alternating, or subareas of the same surface area can follow one another.

Exemplary design variants are explained in more detail below in connection with FIGS. 3A to 3H.

The number of coding options can be further increased by using three or more different IR substances, or by using one or more UV-absorbing substances in addition to the IR substances, or by using two or more IR substances within an area or of a subarea of a surface area are mixed, or by arranging surface areas or subareas of surface areas overlapping one another, or by providing surface areas or subareas of surface areas with an uneven distribution of the IR substance (s), or by giving certain surface areas or subareas of surface areas with a IR-absorbing coating can be fitted. Some of these variants are described in more detail in connection with FIGS. 4A to 4C. It is of course also possible to carry out two or more of the above-mentioned measures in combination.

Areas with an uneven distribution of the IR substance can be obtained, for example, by printing the IR substance using a printing plate with areas of different engraving depth. Areas with deeper engraving take up more ink with an IR-absorbing substance and transfer it to the security element.

With regard to the arrangement of the machine-readable security feature in the vertical layer structure of a security element, several variants are also possible.

On the one hand, the coding can be provided either in one or in several layers of the security element, specifically either in a separate coding layer or in separate coding layers that are used exclusively for coding, or in one or more layers of the security element that also have one serve another purpose, for example in an adhesive layer, in an embossing lacquer layer, or in a protective lacquer layer.

On the other hand, the first and the second IR substance can be provided either both on the front side of the security element or both on the rear side of the security element or one of the IR substances on the front side of the security element and the other of the IR substances on the rear side of the security element . The front side of a security element is considered to be the surface of the security element on which the optically variable effect of the optically variable security feature can best be recognized. The back of a security element is accordingly the surface of the security element opposite the front side.

The application of the machine-readable code to the front or the rear of a security element is not to be understood as meaning that the coding substances necessarily have to be located on a surface of the security element. They can also be located within the layer structure of the security element, but closer to the front side or closer to the rear side, so that their detection succeeds better from the front side or better from the rear side.

Whether the complete machine-readable code can be detected on one side of the security element or whether only part of the machine-readable code can be detected on each side of the security element can be controlled by the arrangement of the IR substances in the security element and by the transparency of the materials, which the detection radiation must penetrate. Some exemplary arrangements of the machine-readable code are described in connection with FIGS. 5A to 5E.

The invention is explained in more detail below with reference to drawings. The figures each represent exemplary embodiments which are in no way to be understood as restricting the invention in any way. In addition, the figures are only schematic representations that do not reflect the real proportions, but only serve for illustration. Only the features essential for understanding the invention are shown in each case and it goes without saying that further features can be present in each embodiment. In addition, features that are shown in different figures can be combined with one another.

The same reference numbers denote the same or similar elements.

Show it:

Fig. 1 shows an embodiment of a fiction like aßen value document in supervision,

2 shows a security element with an optically variable security feature according to the prior art in cross section,

Figures 3A to 3D embodiments of coding areas according to the invention security elements (strips) in plan view,

Figures 3E to 3H embodiments of coding areas of the invention security elements (patches) in a plan view,

FIGS. 4A to 4C show embodiments of coding area structuring of security elements according to the invention in a plan view, and FIG

FIGS. 5A to 5E show embodiments of security elements according to the invention with an optically variable security feature and machine-readable security feature, in cross section.

1 shows a value document 1 according to the invention in a plan view of a surface 6 of the value document. The illustrated document of value 1 has four security elements according to the invention, one Pendulum security thread 2, a window security thread 3, a film strip 4 and a film patch 5. The pendulum security thread 2 is introduced into the value document 1 in such a way that it is partially visible on one surface of the value document and partially on the other surface of the value document. In FIG. 1, the areas visible on the surface 6 shown (hereinafter referred to as the upper side) are labeled with the reference symbol 2 ', while the areas visible on the opposite surface (hereinafter referred to as the underside of the document of value) are labeled with the reference symbol 2 ″ The window security thread 3 has on the upper side 6 of the value document visible areas 3 'as well as areas 3 ″ embedded in the value document substrate. The film strip 4 is attached completely to the upper side 6 of the document of value and covers an opening 8 which passes completely through the document of value substrate. The film patch 5 is also completely attached to the upper side 6 of the document of value 1, for example glued on.

Each of the security elements 2, 3, 4 and 5 can be equipped with a combination of an optically variable security feature and a machine-readable security feature which forms a code in the manner according to the invention. In the embodiment shown, the film patch 5 is equipped with an optically variable security feature 9, for example a moiré magnifier. A machine-readable security feature, not shown in the figure, is arranged in the film patch 5 in such a way that it at least partially overlaps the optically variable security feature 9.

Optically variable security features are often made via openings like the one shown passing through the document of value Opening 8 arranged. They can thus be viewed both in incident light and in transmitted light, with different representations being able to be recognized by a viewer depending on the optically variable security feature. When viewing an optically variable security feature in transmitted light, additional security features that overlay the optically variable security feature can have a particularly disruptive effect on its appearance. However, the coding according to the invention remains hidden from a viewer even when viewed in transmitted light.

In the case of the pendulum security thread 2 and the window security thread 3, the optically variable security feature is located either in the areas 2 'of the pendulum security thread visible on the top 6 of the document of value or in the areas 2 "of the pendulum security thread visible on the underside 7 of the document of value or in the areas 3' of the window security thread The machine-readable security feature is at least partially also located in these areas, but can also extend into areas in which there is no optically variable security feature, for example also in the areas 3 ″ of the window security thread embedded in the document substrate of value. However, it must be ensured that the detectability of the IR substances is guaranteed, i.e. in the case of embedding, the value document substrate must be sufficiently transparent in the absorption range of the IR substances.

2 shows a security element with an optically variable security feature according to the prior art in cross section. A cross-section through a foil patch 5, as shown in FIG. 1, is shown, more precisely a cross-section through a partial area 5 'along the line A-A', but without machine-readable security feature according to the invention. The security element 5 according to the prior art is a moiré magnifier with a layer of microlenses 11, an image layer 13, a spacer layer 12 between the image layer 13 and the microlenses 11, a functional layer 15, which can contain a magnetic security feature, for example, and an adhesive layer 16 for attachment to a value document. In the embodiment shown, the image layer 13 consists of an embossing lacquer in which micro-depressions are embossed. These microwells are filled with a colored substance and form the image elements 14, so-called microimages. The microlenses 11 and the microimages 14 each form a two-dimensional arrangement. When viewed through the microlenses 11, the microimages 14 are enlarged or optically changed in some other way. The image layer 13 and the layer with the focusing elements 11 together form the optically variable security feature.

Security elements according to the invention differ from the security elements of the prior art, such as the security element shown in Fig. 2, in that, in addition to the optically variable security feature, they have a specific machine-readable security feature that forms a code and that (in a plan view of the Considered security element) the optically variable security feature at least partially overlaps. According to the invention, the machine-readable security feature is a combination of at least two substances that both absorb in the IR wavelength range, but in different ways, so that they can be differentiated from one another by machine. According to the invention, these IR substances are arranged in a structured manner so that a machine-readable code is formed. Various Structuring variants are shown in FIGS. 3A to 3H and in FIGS. 4A to 4C.

FIGS. 3A to 3H each show plan views of the machine-readable security feature of security elements according to the invention in the form of film strips. In the illustrated embodiments, the machine-readable code extends essentially over the entire area of the security element, i.e. the machine-readable security feature essentially takes up the entire area of the security element. This is not necessarily the case. Rather, the coding area can also only extend over part of the surface of the security element. The same applies to the optically variable security feature, the area of extent of which represents the optically variable area. In typical foil security elements, the optically variable security features usually extend over a significantly smaller area than the machine-readable security features. Because of the relatively large space required by machine-readable security features, an overlap between the optically variable security feature and the machine-readable security feature can hardly be avoided.

3A shows a simple embodiment of a machine-readable security feature according to the invention. The coding area 10 consists of a first surface area 21 in which the first IR substance is located, a second surface area 22 in which the second IR substance is located, and a third area 23 without IR substance, which separates the first area 21 and the second area 22 from one another. All surface areas extend over the entire length and part of the width of the security element strip and are inherently unstructured. A more complex structuring variant is shown in FIG. 3B. Here, the first area in which the first IR substance is located is divided into sub-areas 31, 32, 33, 34, 35 and 36, and the second area in which the second IR substance is located is in

Sub-areas 41, 42, 43, 44, 45 and 46 divided. The individual sub-areas are each arranged alternately, with some being separated from one another by areas that are free of IR substances. The sub-areas 43 and 33 directly adjoin one another, as do the sub-areas 45, 36, 46. There is also an area 25 in which the sub-area 35 of the first surface area and the sub-area 45 of the second surface area are arranged overlapping one another. Such an overlapping area 25 can be formed, for example, by overprinting the sub-area 35 with the sub-area 45.

In the embodiment of the coding area 10 shown in FIG. 3C, the first area with the first IR substance is subdivided into subareas 31, 32, and the second area with the second IR substance is subdivided into subareas 41, 42, 43. In addition, there is an area 24 in which there is a mixture of the first IR substance and the second IR substance. The regions containing IR substance each have the shape of more or less wide strips which extend transversely to the catch axis of the security element. The areas which contain IR substance are separated from one another by areas 51, 52, 53, 54, 55 which contain no IR substance.

FIG. 3D shows a coding area in the form of a parallelogram with the corner points A, B, C, D. The first surface area with the first IR substance is divided into sub-areas 31, 32, and the second surface area with the second IR substance is subdivided into subregions 41, 42, the subregions which contain IR substance being separated from one another by regions 51, 52, 53 which do not contain any IR substance. The individual subregions have the shape of a bar, as in the illustration in FIG. 3C, but run obliquely to the longitudinal axis of the security element 5.

The coding areas of differently shaped foil patches 5 are shown in FIGS. 3E to 3H.

3E shows a circular foil patch 5, the coding area of which extends over the entire surface of the foil patch. The surface area 21 with the first IR substance and the surface area 22 with the second IR substance form concentric circles around the circular area 23 which does not contain any IR substance.

A circular foil patch is also shown in FIG. 3F. In this patch 5, the coding area is structured in such a way that it has three bar-shaped surface areas with IR substance. The first IR substance is contained in the first area 21, and the second IR substance is contained in the area 41, 42. The surface areas 41 and 42 are arranged on both sides of the surface area 21, with surface areas 51, 52, 53, 54 also remaining in the coding area which do not contain any IR substance.

The embodiment of a security element 5 according to the invention shown in FIG. 3G has the shape of a hexagonal foil patch. The coding area has the shape of a parallelogram with the corner points A, B, C, D. This coding area is filled by a first surface area 21 with the first IR substance and the second Area 22 with the second IR substance. Both surface areas have approximately the same dimensions and are adjacent to one another. In this case, the two IR substances can be used to check the authenticity of the security element, i.e. their absorption spectra and the position within the parallelogram A, B, C, D. When the test area is expanded to include a coding area with the corner points A ' , A, B, B ', C', C, D, D ', the areas 51, 52 can also be used for testing, ie it can be checked whether the areas 51, 52 are free of IR-absorbing substance.

FIG. 3G also shows the position of an optically variable security feature 9 which, like the film patch itself, has a hexagonal shape. As can be seen from FIG. 3G, the optically variable security feature 9 and the machine-readable security feature, ie the coding area 10, are partially congruent. It is therefore important that the presence of the machine-readable security feature does not affect the appearance of the optically variable security feature. In addition, it is also important that the optically variable security feature does not impair the readability of the machine-readable security feature. A machine-readable security feature based on the detection of IR absorptions can be read out without problems as long as either all materials in the radiation path in the wavelength range in question are transparent or the machine-readable security feature is arranged within the security element in such a way that none of them absorb in the detection wavelength range Materials are located between the machine-readable security feature and the detection device. 3H shows a security feature in the form of a square foil patch 5. In this embodiment, the coding area consists of two square areas 31, 32 with a first IR substance and two square areas 41, 42 with a second IR substance, the areas with IR substance can be separated from one another by a cross-shaped area 23 without any IR substance.

It goes without saying that the coding areas shown in FIGS. 3E to 3H can also be provided on security elements with other geometric shapes than the shapes shown in the figures, for example on strip-shaped security elements.

FIGS. 4A to 4C illustrate ways in which the complexity of a coding can be increased without increasing the number of IR substances which are required for the coding.

In the embodiment shown in FIG. 4A, the coding area 10 has five surface areas, a surface area 21 with a first IR substance, a surface area 22 with a second IR substance, the surface areas 51, 52 without IR substance and a surface area 25, in which the surface areas 21, 22 overlap. The overlapping area 25 is not necessarily an area in which the surface areas 21, 22 are in physical contact with one another. Rather, the surface areas 21, 22 can be spaced apart from one another, but can be arranged one above the other in such a way that the IR absorption of the IR substances located in the relevant areas are simultaneously detected by a detection device. In Fig. 4B it is illustrated that for a coding according to the invention not only the type and arrangement of IR-absorbing substances within a certain area can be used, but also that a "sub-coding" within the surface areas in which a certain IR- 4B shows a coding region 10 which has surface regions 26, 26 'with a first IR substance and surface regions 27, 27' with a second IR substance, wherein between the regions with IR Substance is a surface area 23 without IR substance. In each of the surface areas 26, 26 ', 27, 27' there is a gradient with regard to the amount or concentration of the IR substance. A larger amount of IR substance is in each case Such a quantity gradient can be achieved by a non-uniform printing of the IR substances, for example by means of printing plates with varying gravure rdepth.

Alternatively, regions with the same IR substance, for example the subregions 31, 32, 33, 34, 35, 36 in FIG. 3B, can each have different amounts of the same IR substance. This can also be achieved using printing plates that have different engraving depths in the corresponding areas. According to a further embodiment, the impression can also be created for only one detection device that a specific IR substance is present in different amounts in different areas. This can be achieved, for example, by providing areas that contain a certain IR substance in the same amount with a more or less strong IR-absorbing overpressure. Alternatively, more or less of an IR absorber can be added to the IR substance that is applied to certain areas. FIG. 4C shows an embodiment in which the measures shown in FIGS. 4A and 4B for increasing the complexity of coding are combined. The surface areas 26, 27 'described in FIG. 4B are shown, which, however, are arranged overlapping one another, analogous to the arrangement shown in FIG. 4A. This creates the overlap area 28 in which the absorption of a small amount of the IR substance of the surface area 26 and the IR absorption of a higher amount of the IR substance of the surface area 27 'are detected.

FIGS. 5A to 5E are representations as in FIG. 2, but each of which has a machine-readable security feature according to the invention. A partial area (partial area 5 ', cross section along line A-A' in FIG. 1) of a security element 5 according to the invention is shown in each case.

All security elements shown have a machine-readable security feature that forms a code by means of a first IR substance 17 and a second IR substance 18. The security elements differ with regard to the locations at which the first IR substance 17 and the second IR substance 18 are arranged in the layer structure of the security element 5.

In the security element shown in FIG. 5A, both the first IR substance 17 and the second IR substance 18 are located in depressions in the spacer layer 12, ie both IR substances are at the same level within the layer structure, and both IR substances are located on the front side or the top side 6 'of the security element 5. In this embodiment, the machine-readable security feature is read out from the front side (side with focusing elements 11) of the security element, as indicated by the arrow that is not filled in.

In the security element 5 shown in FIG. 5B, the first IR substance 17 and the second IR substance 18 are both located in the functional layer 15, ie at the same level within the layer structure of the security element, and close to the rear side or the underside 7 'of the security element. In this embodiment it can be more expedient if the machine-readable security feature is read out from the rear side of the security element, as indicated by the arrow that is not filled in.

In the security element shown in FIG. 5C, the components of the machine-readable security feature are located in different layers of the security element 5. The first IR substance 17 is located in depressions in the spacer layer 12, and the second IR substance 18 is located in the functional layer 15. Depending on the materials used or their IR absorption properties, when the machine-readable security feature is read from the front 6 'of the security element, only the IR absorption of the first IR substance 17 is detected, while when the machine-readable security feature is read from the rear 7 'of the security element, only the IR absorption of the second IR substance 18 is detected. This detectability in each case only on one side of the security element can be used as an additional authenticity criterion.

In the security elements shown in FIGS. 5D and 5E, the first IR substance 17 and the second IR substance 18 are arranged in such a way that they partially overlap one another. In the one shown in Fig. 5D In the security element 5, the first IR substance 17 is located in the adhesive layer 16, and the second IR substance 18 is located in the functional layer 15. The first IR substance 17 and the second IR substance 18 contact one another in the overlap area 19. kn In contrast to this, in the security element shown in FIG. 5E, the first IR substance 17 and the second IR substance 18 are not located in adjacent layers of the security element 5. Rather, the first IR substance 17 is located in the functional layer 15, and the second IR substance 18 in the spacer layer 12. With a vertical view of the front 6 'or the rear 7' of the security element, indicated by the arrows that are not filled in, there is nevertheless an area 19 in which the areas of the first IR Substance 17 and the second IR substance 18 overlap. In this overlap region 19, the IR absorptions of the first IR substance 17 and the second IR substance 18 are jointly detected by an IR detector.

The invention has been described above using the example of security elements with microlens arrangements. It goes without saying, however, that the multicoding according to the invention based on IR substances is suitable for any type of security element or document of value, provided that care is taken that in the areas that must be accessible for detection of the IR substances, none Materials are used which attenuate the intensities to be measured too much. As a rule, this can easily be achieved by providing the IR substances in areas of a security element that are close to the surface. "Critical" components of a security element, including in particular metallizations that are present in many security features, for example in holograms and thin-film elements, have an effect does not have a negative impact on the detectability of the multicoding according to the invention if the coding IR substances are arranged in the layer structure of a security element in such a way that none of the critical components of the security element lies in the beam path during detection.

The multicoding according to the invention is suitable for security elements and documents of value with substrates made of polymer materials and based on paper, and also for hybrid substrates (e.g. film / paper / film composite substrates or paper / film / paper composite substrates). It enables not only a reliable authenticity check of the value documents equipped with it, but also a denomination recognition of banknotes. In addition, the use of several IR substances, which also have to be applied to very specific locations and in a very specific pattern, achieves a high degree of protection against forgery. In particular, overlapping areas of the IR-absorbing substances are difficult to recognize as such for a counterfeiter and are therefore particularly difficult to imitate. Just because the multicoding according to the invention is practically not recognizable in visible light, a certain degree of protection against forgery is achieved, since a potential forger assumes that the authenticity assurance should be ensured by the visible security element, the appearance of which is not influenced by the multicoding according to the invention becomes.

Claims

P a te n claims

1. Security element with an optically variable security feature and a machine-readable security feature, which are at least partially arranged one above the other, wherein the security element is transparent or translucent for wavelengths of visible light at least in the area of the optically variable security feature and the machine-readable security feature forms a code, characterized in that, that the machine-readable security feature is a combination of at least two different substances, a first IR substance and a second IR substance, the first IR substance in a first surface area of the

Security element is arranged and the second IR substance is arranged in a second surface region of the security element different from the first surface region, and the first IR substance absorbs in a first IR wavelength range and the second IR substance in a second IR

Absorbs wavelength range that is machine distinguishable from the first IR wavelength range.

2. The security element according to claim 1, characterized in that the first surface area and the second surface area overlap one another in at least one overlapping area.

3. Security element according to claim 1 or 2, characterized in that it has at least one substance absorbing in the UV wavelength range.

4. Security element according to one of claims 1 to 3, characterized in that the first IR substance and the second IR substance are both arranged close to the front surface of the security element.

5. Security element according to one of claims 1 to 3, characterized in that the first IR substance and the second IR substance are both arranged close to the rear surface of the security element.

6. Security element according to one of claims 1 to 3, characterized in that the first IR substance is arranged close to the front surface of the security element, and the second IR substance is arranged close to the rear surface of the security element.

7. Security element according to one of claims 1 to 6, characterized in that it has a layer structure with several layers, the first IR substance and the second IR substance being arranged in the same layer or in different layers of the layer structure.

8. Security element according to one of claims 1 to 7, characterized in that the first surface area and / or the second surface area is divided into at least two sub-areas, the IR- Absorption intensity of at least two sub-areas of the first area and / or of at least two sub-areas of the second area is different.

9. Security element according to one of claims 1 to 8, characterized in that the first surface area and / or the second surface area is divided into at least two sub-areas, the IR absorption intensity varying within at least one sub-area as a function of location.

10. Security element according to one of claims 1 to 9, characterized in that it has at least one surface area in which the first IR substance and the second IR substance are present in the form of a mixture.

11. Security element according to one of claims 1 to 10, characterized in that the first IR substance and / or the second IR substance is an iron (II) or a copper (II) compound.

12. Security element according to one of claims 1 to 11, characterized in that the first surface area with the first IR substance and / or the second surface area with the second IR substance was generated using a printing ink selected from SICPTALK®CBA , NFB, ETM and SEN / SEL printing inks.

13. Security element according to one of claims 1 to 12, characterized in that the optically variable security feature is a moiré magnifier.

14. Security element according to one of claims 1 to 13, characterized in that it is a security thread, a security strip, a foil patch or an independent document of value.

15. Document of value, such as bank note, identification document, credit card or

Document, characterized in that it is equipped with a security element according to one of Claims 1 to 14.