EP3738786B1 - Luminescent security element - Google Patents

Description

Subject of the invention

The present invention relates to a security element for use in a security document and a method for producing a security element for use in a security document. The invention also relates to a security document and a method for producing a security document.

Background of the invention

To increase the security against forgery of security documents, especially valuable documents, different features and processes are used that make it difficult or impossible to copy or falsify them. A security document is usually made up of several layers that are preferably bonded together by lamination. The data is incorporated into the material under a preferably transparent cover layer to protect it from manipulation. This can be achieved by laser personalization in the otherwise finished data carrier. Another process involves providing the data carrier with a preferably transparent cover layer after personalization.

A valuable or security document can be tampered with by removing the cover layer and, after manipulating the underlying data, applying a new cover layer. Holograms can be used to protect the document from manipulation, as in the documents WO 2017 109 119 A1 , EN 10 2007 042 386 A1 , EP 2 738 624 B1 described. For this purpose, a special hologram foil is exposed accordingly and applied to the data carrier. Furthermore, the surface of a security document can be microstructured, which makes any manipulation of the cover layer recognizable. Another possibility is described in the document EP 1 970 211 A1 The document is labelled with a laser on the narrow side surfaces to create an optical connection between the layers. In the documents WO 98/19869 or. DE 697 23 283 T2 A security feature is presented in which information is inserted into several layers of the document by perforating the data carrier.

From the document EN 10 2012 218 053 A1 The use of a luminescent film in conjunction with an absorbing spectral filter medium to produce a security feature is known.

WO 2012/046212 A1 discloses a security document with a multi-layer security element, which has a first and a second inner layer. The two layers can be made of a fibrous material, such as paper, for example. In one variant, however, they can also be luminescent. Holes are provided in the security element. The holes can be made by laser, extend into the layers and have a diameter of 10 to 50 µm.

Out of WO 03/032242 A1 is a code that is printed onto a substrate using the intaglio printing process. Individual coding areas differ in their ink layer thickness. The printing ink contains luminescent, electrically conductive, X-ray absorbing or infrared radiation absorbing substances, so that the ink layer thicknesses can be differentiated based on different signal intensities.

An identification document with a substrate and a laminating film is in EP 2 308 687 A1 The surface of the substrate facing the laminating film bears first text, number and/or image data that can be seen with the naked eye, as well as a first surface area with a fluorescent substance. The substance fluoresces when excited with light in a certain wavelength range, colored and recognizable to the naked eye. The laminating film has a second surface area that carries second text, number and/or image data. The first surface area of the substrate surface and the second surface area of the laminating film overlap each other at least partially. The fluorescent substance is visible through engravings in the laminating film.

WO 2012/041851 A1 discloses a security element having a security feature that changes visual appearance upon exposure to UV light and rotation or tilting.

Out of EN 10 2013 203 303 B3 The patent holder here knows a security feature with an optical element that is made of a material having a first refractive index and has an optically refractive structure at which radiation incident on the security feature from an ambient medium having a second refractive index is refracted or totally reflected. For individualization, the optical element is overlaid in a pattern-forming area with a transparent structuring medium that has a third refractive index.

Furthermore, EN 10 2007 024 298 B3 a film element for authenticity detection, which is characterized by the fact that it comprises a transparent film that has luminescent information. The luminescent information is introduced by means of laser processing, such as laser engraving, steel embossing or intaglio printing.

The documents GB 2 382 546 A and US 2014/0339298 A1 reveal additional security features with multiple layers.

The following definitions are taken from the document EP 2 738 624 B1 As already defined there, in the context of the present invention, a security element is understood to be a physical unit that includes at least one security feature. Security elements serve to protect security documents, which also include value documents, against forgery or copying. A security feature can be an independent physical unit that can be connected, for example glued or welded, to a security document, which can also be a value document. However, it can also be an integral part of a security document. A security feature is an object that can only be produced or reproduced without authorization with increased effort compared to simple copying, or not at all.

Security documents typically comprise a substrate, a print layer and optionally a transparent cover layer. A substrate is a support structure onto which the A printing layer with information, images, patterns and the like is applied. Materials for a substrate include all standard paper and/or plastic-based materials. Examples of security documents are identity cards, passports, driving licenses, ID cards, access control cards, visas, tax stamps, tickets, vehicle documents, banknotes, checks, postage stamps, credit cards, any chip cards and adhesive labels.

In the following, luminescence is understood to mean fluorescence and phosphorescence with Stokes shift and/or anti-Stokes shift. Luminescence is preferably photoluminescence, but it can also be electroluminescence.

Description of the invention

Against the background described, the object of the present invention is to further improve the forgery security of security elements and security documents.

This object is achieved by a security element for use in a security document according to claim 1, a security document according to claim 12, a method for producing a security element for use in a security document according to claim 13 and a method for producing a security document according to claim 14. The dependent claims contain further advantageous embodiments of the invention.

The security element according to the invention is designed for use in a security document, for example as a component or as a layer arrangement in the context of a security document. It comprises a personalized layer and a luminescent layer. The personalized layer preferably comprises personalized information, for example visible personalized information. The luminescent layer comprises a structure made up of a number of structural elements with dimensions between 0.1 micrometers (0.1 µm) and 20 micrometers (20 µm).

The structural elements cause a deflection of light rays that hit them. By using luminescent material, the structure is easily visually perceptible as a luminous element. The luminescent layer has a structure that includes personalized information. The personalized information in the luminescent layer matches or correlates with information in the personalized layer. The structuring preferably takes the Information or data from the underlying data carrier so that the surface or cover layer cannot be manipulated or separated and replaced from the rest of the data carrier without being noticed.

The present invention enables a valuable and/or secure document to be secured by a security element which, in addition to a personalized layer, has a luminescent layer with a preferably personalized structure. Manipulation or replacement of the personalized layer or damage to the luminescent layer is thus easily detectable.

The security element preferably comprises at least one layer which comprises laser-sensitive material, i.e. material suitable for processing using a laser, or which consists of laser-sensitive material. The luminescent layer advantageously comprises laser-sensitive material. Laser-sensitive material enables simple and cost-effective production of the structural elements, in particular production of structural elements with very small dimensions.

The structural elements have dimensions of less than 20 micrometers (20 µm). The smaller the dimensions, the more difficult it is to counterfeit or tamper with the security element. On the other hand, the structural elements should preferably have dimensions larger than the wavelength of visible light, which is why, for example, structural elements with dimensions of greater than 1 micrometer (1 µm) can be used.

In an advantageous variant, the personalized layer has a surface and the luminescent layer is arranged above the personalized layer with respect to a surface normal of the personalized layer. With such a design, the visually perceptible structure in the luminescent layer can be optically easily compared with also visually perceptible structures or information of the personalized layer.

The structural elements are preferably colorless. This makes imitation or manipulation more difficult, as the structural elements are only visible when luminescence occurs. The luminescent layer can be optically at least partially transparent, in particular completely transparent. This also makes counterfeiting more difficult, as it is not initially apparent that a luminescent layer is present at all.

The luminescent layer preferably has a surface, wherein the surface can comprise a top side and a bottom side of the luminescent layer, and at least one structural element is arranged on the surface and/or in the surface and/or in the interior of the luminescent layer. At least one structural element can be designed as a depression, in particular in the form of a micro-bore or micro-engraving, or an elevation or cavity. The structural elements can be arranged both on the top side and on the bottom side of the luminescent layer or in the interior of the layer. The design variants mentioned further improve the security against counterfeiting.

Preferably, the luminescent layer forms a cover layer, for example a transparent cover layer, of the security element. In this variant, existing security elements and security documents can also be retrofitted and thus improved in terms of their forgery security.

In a further preferred embodiment, the security element comprises at least one window area and the security element and the structural elements of the luminescent layer are located in the at least one window area of the security document. In this embodiment, the structural elements are visible from both sides of the document. The structural elements appear bright when viewed in reflection against a dark background and dark when viewed in transmission against a bright background.

The security element can, for example, be designed for a specific security document or for a specific type of security document with specific security information. The structure of the luminescent layer can contain security information and/or personalized data for the specific security document. The structure of the luminescent layer can, for example, include information that is also contained in the personalized layer. The security information and/or personalized data can be information that can be assigned to the holder of the security document.

The luminescent layer can be designed as a film. This enables simple and cost-effective production, as well as easy processing in connection with the introduction of the structural elements into the luminescent layer.

The luminescent layer can comprise polycarbonate and/or glass, in particular luminescent glass. The luminescent layer can comprise fluorescent and/or phosphorescent and/or laser-sensitive material. The use of laser-sensitive material enables processing by means of a laser and in particular introduction of the structure by means of a laser.

Preferably, the luminescent layer has a refractive index that is higher than 1.1, for example a refractive index between 1.2 and 2. This means that total reflection predominantly occurs at the interface of the luminescent layer and light is only scattered at the structural elements in such a way that it can leave the luminescent layer and the structure thus becomes visible.

The security document according to the invention is made up of a number of layers, preferably two or more layers. It comprises a previously described security element according to the invention. The security document according to the invention has the features and advantages mentioned above in connection with the security element according to the invention. It can in particular comprise laminated layers. The security document can be, for example, an identity card, a passport, a driving license, a company ID card or another security document.

In the context of the method according to the invention for producing a security element according to the invention for use in a security document, structural elements, in particular structural elements with dimensions in the micrometer range, are produced in the luminescent layer by means of laser radiation and at least one personalized layer is firmly connected to the luminescent layer. The structural elements in the luminescent layer can be produced before or after the luminescent layer is connected to the personalized layer.

The structural elements can be produced using ultrashort laser pulses, for example with a pulse duration of less than 10 picoseconds (10 ps), in particular less than 1 picosecond (1 ps) or less than 500 femtoseconds (500 fs). Micro- or nano-laser structures in particular can be produced relatively easily using ultrashort laser pulses. The use of ultrashort laser pulses enables precise production and efficient production of the structural elements. In particular, ultrashort laser pulses minimize or prevent thermal or mechanical damage to the structural elements during processing. With a suitable choice of processing parameters, a Almost melt-free processing with high precision is possible. Due to the short interaction time of the ultra-short laser pulses with the material, the material removal does not cause any color change in the material and the elements of the structure are colorless and preferably consist of micro-drills or micro-engravings. The luminescent film shows a light emission at the edges and at the laser-engraved edges and holes that is clearly visible to the naked eye or under a microscope. The structure is therefore clearly perceptible when viewed as a luminous element.

When creating the structural elements, the luminescent layer or several layers that are already connected to one another can be moved relative to a focused laser beam and/or scanned by a focused laser beam. The movement of the layer or layers relative to a focused laser beam preferably takes place in an x-y plane parallel to the surface of the layers to be processed. Scanning can be carried out using movable mirrors.

Within the scope of the method according to the invention for producing a security document according to the invention, at least one security element according to the invention or a security element produced according to the invention is connected to a number of further layers.

Due to the dimensions and optical properties, such as the transparency of the structure and the colorlessness of the structural elements, the structure presented can only be generated with practical effort using ultra-short laser pulses and cannot be imitated mechanically. Preferably, a directly recognizable connection can be established between the structure introduced into the cover layer and the information in the underlying layer of the data carrier. This makes any manipulation of the surface or replacement of the cover layer directly recognizable.

Description of implementation examples

Further features, characteristics and advantages of the present invention are described in more detail below using embodiments with reference to the accompanying figures.

The figures are not necessarily detailed or to scale and may be shown enlarged or reduced in size for clarity of illustration. Therefore, functional details disclosed herein are not to be interpreted in a limiting sense, but merely as an illustrative basis for providing guidance to one skilled in the art to variously employ the present invention.

Fig. 1

zeigt schematisch eine lumineszierende Schicht in einer Schnittansicht.

Fig. 2

zeigt schematisch eine erste Variante einer lumineszierenden Schicht eines erfindungsgemäßen Sicherheitselements in einer Schnittansicht.

Fig. 3

zeigt schematisch eine zweite Variante einer lumineszierenden Schicht eines erfindungsgemäßen Sicherheitselements in einer Schnittansicht.

Fig. 4

zeigt schematisch eine dritte Variante einer lumineszierenden Schicht eines erfindungsgemäßen Sicherheitselements in einer Schnittansicht.

Fig. 5

zeigt schematisch ein erfindungsgemäßes Sicherheitselement in einer Schnittansicht.

As used herein, the term "and/or" when used in a series of two or more elements means that any of the listed elements may be used alone, or any combination of two or more of the listed elements may be used. For example, if a composition is described as containing components A, B, and/or C, the composition may contain A alone; B alone; C alone; A and B in combination; A and C in combination; B and C in combination; or A, B, and C in combination.

Fig.1

shows schematically a luminescent layer in a cross-sectional view.

Fig.2

shows schematically a first variant of a luminescent layer of a security element according to the invention in a sectional view.

Fig. 3

shows schematically a second variant of a luminescent layer of a security element according to the invention in a sectional view.

Fig.4

shows schematically a third variant of a luminescent layer of a security element according to the invention in a sectional view.

Fig.5

shows schematically a security element according to the invention in a sectional view.

The Figure 1 shows, by way of example and not to scale, a cross-section of a luminescent layer 100, for example a cover layer, for a security element, wherein the possible beam paths of the incident light are shown. The luminescent layer 100 has a surface. The surface of the upper side of the luminescent layer 100 is identified by the reference number 200 and the surface of the lower side of the luminescent layer 100 is identified by the reference number 201.

The luminescent layer 100 preferably comprises a transparent base material, for example polycarbonate with a refractive index of approximately n ₂ =1.54. The refractive index of the ambient air is designated by n ₁ and is approximately n ₁ =1.

The incident rays 1 of the ambient light can be transmitted through the transparent base material or they are absorbed by a fluorescent or luminescent molecule 101 within the base material 100. The light beam refracted at the top 200 is identified by the reference number 2. The associated optical axis is identified by the reference number 11. The molecule 101 excited by the light absorption then emits light 4 that is characteristic of the molecule and which generally has a Stokes shift. If the light rays 4 emitted in this way hit an interface 200 with different refractive indices n ₁ and n ₂ , where the refractive index of the material n ₂ is greater than the refractive index n ₁ of the environment, the rays 3 leave the layer 100 at a steep impact, i.e. at a small angle to the optical axis 12.

However, a large proportion of the light rays 4 strike the interface 200 at a shallow angle 5 to the surface and are totally reflected. The corresponding optical axes for the example rays shown are marked with the reference numbers 13 and 14. The totally reflected light rays 7 only strike the interface of the layer 100 at the edge 8 of the material 100 at an angle 6, which allows the light rays 3 to exit the material. This material therefore usually has a luminous edge 8.

The Figures 2 and 3 show the cross-section of a luminescent layer 100 which has been modified by laser material processing. The holes 210, 212 and engravings 210, 212 or raised areas 211 introduced by means of laser radiation change the interface 200 of the material 100. In the case of the Figure 2 In the variant shown, material changes 210, 211 have been made on the upper side 200. In the Figure 3 In the variant shown, material changes 212, 102 have been made on the underside 201 and inside the layer 100. The Figures 2 and 3 The variants shown can also be combined with each other. The structural elements 102, 210, 211, 212 have dimensions between 0.1 micrometers (0.1 µm) and 20 micrometers (20 µm).

The light rays 4 generated within the material by the fluorescent or luminescent molecules 101, which are generated in particular due to total reflections at the Interface 200 remain in the material, hit the respective interface at the modified points 210, 211, 212, 102 at an angle to the optical axis 17, 18, 19, 20, 21, 22, which allows the light rays 3 to exit the material at this point. As a result of the light rays 3 exiting at the processed points 210, 211, 212, 102, these points glow in the color or wavelength typical for the material or for the fluorescent or luminescent molecules contained therein. Since laser material processing is possible in the micrometer range, this makes it possible to produce a clearly visible, very finely structured security feature, which can in particular contain personalized information.

The Figure 4 shows, by way of example, the cross-section of a luminescent layer 100 which has been modified by laser material processing. The beam path with transmitted illumination is shown as an example. This approach is possible when the security element is designed in the form of a window in the security document. The holes 210 introduced by means of laser radiation change the interface 200 of the material 100. As a result, transmitted light 1 is deflected in the directions 3 such that the structural elements 210 appear darker than the unprocessed surfaces. In the Figure 4 The interface 200 shown can be a top or a bottom of the luminescent layer 100.

The Figure 5 shows schematically a section of a security element 30 according to the invention in a sectional view. The security element 30 comprises a personalized layer 300 with a surface 302 that has a surface normal 301. A previously described luminescent cover layer 100 is arranged above or on the personalized layer 300 with respect to the surface normal 301. The security element 30 according to the invention can be connected to further layers in the context of a security document, for example by lamination.

List of reference symbols:

1

incident light beam

2

refracted light beam

3

emerging light beam

4

scattered light beam

5

angle

6

angle

7

totally reflected light beam

8th

edge

11

optical axis

12

optical axis

13

optical axis

14

optical axis

15

optical axis

16

optical axis

17

optical axis

18

optical axis

19

optical axis

20

optical axis

21

optical axis

22

optical axis

30

Security element

100

luminescent layer

101

fluorescent or luminescent molecule

102

Structural element

200

Surface of the top

201

Surface of the bottom

210

Structural element

211

Structural element

212

Structural element

300

personalized layer

301

Surface normal

302

surface

n1

Refractive index

n2

Refractive index

Claims (14)

1. A security element (30) for use for a security document, the security element (30) comprising a personalised layer (300) and a luminescent layer (100), the luminescent layer (100) having a structure of a number of structural elements (102, 210, 211, 212), the structure comprising personalised information that matches or correlates with information in the personalised layer (300), characterised in that the structural elements (102, 210, 211, 212) have dimensions between 0.1 micrometres (0.1 µm) and 20 micrometres (20 µm).
2. The security element (30) according to claim 1, characterised in that the personalised layer (300) comprises a surface (302) and that the luminescent layer (100) is disposed above the personalised layer (300) with respect to a surface normal (301) of the personalised layer (300).
3. The security element (30) according to any one of the claims 1 to 2, characterised in that the structural elements (102, 210, 211, 212) are colourless.
4. The security element (30) according to any one of the claims 1 to 3, characterised in that the luminescent layer (100) is optically at least partially transparent.
5. The security element (30) according to any one of the claims 1 to 4, characterised in that the luminescent layer (100) comprises a surface (200, 201) and that at least one structural element (102, 210, 211, 212) is disposed on the surface (200, 201) and/or in the surface (200, 201) and/or in the interior of the luminescent layer (100).
6. The security element (30) according to any one of the claims 1 to 5, characterised in that at least one structural element (102, 210, 211, 212) is formed as a depression or elevation or cavity.
7. The security element (30) according to any one of the claims 1 to 6, characterised in that the luminescent layer (100) forms a cover layer of the security element (30).
8. The security element according to any one of the claims 1 to 7, characterised in that the security element comprises at least one window region and that the luminescent layer having at least one structural element is disposed in the at least one window region and is visible in reflection and in transmission.
9. The security element (30) according to any one of the claims 1 to 8, characterised in that the security element (30) is designed for a specific security document or for a specific type of security document having specific security information and that the structure of the luminescent layer (100) contains security information for the specific security document.
10. The security element (30) according to any one of the claims 1 to 9, characterised in that the luminescent layer (100) comprises fluorescent and/or phosphorescent and/or laser-sensitive material.
11. The security element (30) according to any one of the claims 1 to 10, characterised in that the luminescent layer (100) has a refractive index greater than 1.1, preferably between 1.2 and 2.
12. A security document composed of a plurality of layers, characterised in that said security document comprises a security element (30) according to any one of the claims 1 to 11.
13. A method for producing a security element (30) for use for a security document and according to claim 12, characterised in that structural elements (102, 210, 211, 212) are generated in the luminescent layer (100) by means of laser radiation and at least one personalised layer (300) is firmly connected to the luminescent layer (100), wherein the structural elements (102, 210, 211, 212) are preferably generated by means of ultrashort laser pulses, and wherein during the generation of the structural elements (102, 210, 211, 212) the luminescent layer (100) is preferably displaced relative to a focussed laser beam and/or is scanned by a focussed laser beam.
14. The method for producing a security document according to claim 12, characterised in that at least one security element (30) according to any one of the claims 1 to 11 or a security element (30) produced according to claim 13 is connected to a plurality of further layers.

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