EP2485901A1

EP2485901A1 - Security element for detecting authenticity

Info

Publication number: EP2485901A1
Application number: EP10784953A
Authority: EP
Inventors: Loessl Fariborz Martin Zahedi
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-10-09
Filing date: 2010-10-08
Publication date: 2012-08-15
Also published as: DE102009048870B3; WO2011042010A1; US20120187674A1

Abstract

The present invention relates to a security element for detecting authenticity, in particular of security documents, bank notes, valuable documents, coins, chips, useful objects, design elements, data carriers, and similar objects. The security element according to the invention comprises a first layer (101) that is transparent to light and that has an index of refraction n1 and that has a surface (108) on a first side (108) of the first layer (101), said surface having a structure (105), a second layer (102) arranged on the first layer (101) directly on the structured surface (108), said second layer having an index of refraction n2, wherein n2 ≠ n1, in particular n2 >> n1 or n2 << n1, and the transmittance T of the light through the second layer (102) varies depending on location in the second layer (102) according to a specifiable continuous function T = T(x,y), and x and y are location coordinates in a layer plane of the second layer, and a third layer (103), which has a luminescent material and is transparent to the light and is arranged on the side of the second layer (102) opposite the first layer (101) and is connected to the second layer (102) in a light conducting manner, or is arranged on the second side (107) of the first layer (101) opposite the first side of the first layer (101) and is connected to the first layer (101) in a light conducting manner.

Description

Security element for authentication

The present invention relates to a security element for authenticating, in particular security documents, banknotes, documents of value, coins, chips, utensils, design elements, data carriers and the like objects.

Security features for authentication of authenticity are known in the art. Thus, for example, from the document DE 10 2007 024 298 B3

Security element for authenticity detection, which is characterized by the fact that it comprises a daylight fluorescent dye colored, light-collecting and photoconductive transparent film in which by targeted disruption of the foil's total reflection, a motif is introduced, which luminesces under ambient light in the visible spectrum. Such security elements are

typically designed as a security strip, security surface, etc. and connected to security documents, banknotes and similar objects such that a detachment of the security element leads to the destruction of the respective object. The security elements are intended to ensure the unique and reliable recognition of the authenticity of the associated objects described above. Furthermore, the security elements should be designed such that a replica or forgery of the security elements or the objects provided with them,

For example, by a simple copying or similar procedures is possible excluded. A variety of different security elements are known in the art, which typically have several different layers into which characters, barcodes, motifs, images or other optical

Information, for example, as engraving, blackening or hologram are introduced. In this case, the optical information contained in the security element can be visible or not visible to a viewer depending on the viewing angle.

The object of the present invention is to provide a security element for authenticating, which is inexpensive to produce, enables a reliable recognizability of authenticity, as well as an anti-counterfeiting security

CONFIRMATION COPY ensures, for example, a forgery by simply copying the

Security element makes impossible with a commercially available copier.

The invention results from the features of independent claim 1.

Advantageous developments and refinements are the subject of the dependent claims. Other features, applications and advantages of the invention will become apparent from the following description, as well as the explanation of embodiments of the invention, which are illustrated in the figures.

The object is achieved by a security element for authentication,

in particular of security documents, cash or similar objects, which has a light-transparent first layer having a refractive index ni, having a structure having a surface on a first side of the first layer, a second layer disposed on the first layer directly on the structured surface a refractive index n ₂ , where n ₂ = n, in particular n ₂ »ni or n ₂ ni, and the transmission T of the light through the second layer according to a predefinable continuous function T = T (x, y) is location-dependent in the second layer varies, and x and y are locus coordinates in a layer plane of the second layer, and a luminescent material having the light transparent third layer which is disposed on the opposite side of the first layer of the second layer, and with the second Layer light is conductively connected, or at the first side of the first layer

opposite second side of the first layer is arranged and is conductively connected to the first layer, has.

It has been shown that with such a security element when viewing the security element, optical effects which depend on the viewing angle can be achieved which make it impossible to forge the security element simply by copying a banknote provided with the security element according to the invention with a commercially available copying machine. Furthermore, that is

Security element inexpensive to produce.

The security element is preferably designed as a strip or planar element and thus on the object whose authenticity it is to identify applied, that the third layer is disposed closest relative to the object, for example, is glued to the banknote. The security element can be mounted on the surface of the respective object to be marked, or it can be incorporated into the object.

Comprising at least the three layers described above

The security element according to the invention preferably has a thickness of <100 μιη, preferably <50 μιη, and particularly preferably a thickness of 5 to 30 pm. This thickness corresponds in particular to the thickness of the security strips customary today for banknotes. The security element is preferably flexible overall, i. flexible, allowing the security element even on flexible objects, such as

Banknotes, security papers, etc. can be used and thus

rolled or kinked as far as possible without damage, without losing its security and authenticity detection function.

The above, the light-related features of the invention

Security elements such as "transparent to light", "transmission of light" and "light-conducting connected" preferably refer to electromagnetic radiation having wavelengths in the range of 1 nm to 1000 nm, in particular in the range of 380 to 780 nm, ie the visible light spectrum. In a further preferred embodiment of the security element for authenticity detection, the properties relating to the light relate to electromagnetic radiation

Wavelengths in the range of 1 nm to 380 nm, i. in particular to ultraviolet radiation, which is not visible to the eye and can only be detected by means of appropriate UV light sources or UV sensors. This embodiment is suitable for applications in which the authenticity recognition should not be accessible to everyone and for the authenticity detection corresponding aforementioned special means are needed.

According to the invention, the security element for authentication of authenticity consists of three layers. In this case, the first layer has on its first side a structure having surface. In the present case, the term "structure" is broadly defined, in particular as far as structural forms are concerned, The structure designates, for example, a predeterminable arrangement (pattern, etc.) of elevations and depressions predeterminable shapes (edges, curves, etc.) on the surface of the underside of the first layer. The structure particularly preferably has a concentric, elliptical, parallel, trapezoidal or star-shaped geometry. Particularly preferably, the structure has the annular step structure of a Fresnel lens.

In a further preferred embodiment of the security element, the structure has the ring structure of a Fresnel zone plate. In this case, the structure has concentric rings, ring zones differing in their transparency and / or their optical path length through the first layer. For example, zone plates with binary gradation are known in which transparent ring zones with opaque, i. alternate completely absorbing ring zones. The incident light is distributed to many real and virtual foci. Thus, in one case, the light can be diffracted at the annular column structures and amplified by constructive interference in foci. In the other case, the ring zones are replaced by a transparent material of precisely determined thickness (which leads in cross section to alternating rectangular structures), which causes a phase shift of the light wave of 180 °, whereby the light transmitted through the first layer in the focal point constructively interferes.

Due to the structured surface on the first side of the first layer, when viewed on the second side of the first layer, optical effects are produced, depending on the viewing angle, which, for example, have the effect of a lens or produce a spatial impression in the viewer, and which, for example, only at certain viewing angles allow detection of an optical information contained in the security element. These optical effects are through

Refraction generated at the structured surface. Furthermore, the structure may be configured such that diffraction effects are generated as in the case of the Fresnel zone plate. The light-transparent first layer preferably occupies the greatest part in the security element with regard to the thickness of the security element, for example half to two thirds of the thickness of the security element

Security element. The second side of the first layer is preferably flat (planar) and has no structure. To protect against wear, the second side of the first layer can be mechanically transparent for light

Protective layer applied. At the first layer is according to the invention directly to the structured

Surface of the first side of the first layer applied or arranged a second layer. In accordance with the invention, the transmission T of the light through this second layer varies in a location-dependent manner in the second layer according to a predefinable continuous function T = T (x, y), where x and y are location coordinates in the layer plane. The first layer also has a refractive index ni and the second layer has a refractive index n ₂ , wherein according to the invention it is true that n ₂ n, in particular n ₂ ni or n ₂ ni. In the case of n ₂ = ni, the optical effect of the structure of the first layer would not be able to develop since, in this case, no refraction of light occurs in the transition from the first layer to the second layer. The optical effect of the structure is therefore all the more pronounced, that is perceptible to a viewer, the greater the difference of the refractive indices η-ι and n ₂ . The skilled person can influence or vary the desired optical effect of the corresponding structure by choosing appropriate materials for the first and the second layer.

The transmission in the present case is understood to mean the permeability of a medium (for example the second layer) for electromagnetic waves (light). The transmittance is preferred as transmittance [0-100%].

which is defined as the quotient of the wave intensity before and after passing through the medium. In the present case, particular optical effects can be achieved by additionally depending on the wavelength and the angle of incidence of the light transmission in the choice of the materials of the three layers

considered and used accordingly to achieve additional optical effects.

A preferred embodiment of the security element according to the invention is characterized in that the second layer contains metallic elements or is completely formed by metallic elements whose concentration C (x, y) varies in the layer plane in a location-dependent manner such that the transmission T corresponds to the function T = T (x, y) varies continuously. A further preferred embodiment of the security element according to the invention is characterized in that the second layer contains metallic elements or is completely formed by metallic elements, and the thickness D (x, y) of the second layer varies as a function of location in the layer plane such that the transmission T varies continuously according to the function T = T (x, y).

The application of the metallic elements to the structured surface takes place, for example, by vapor deposition of a metallic layer having different thicknesses

Layer thickness D (x, y) or with different concentration C (x, y) on the

structured surface of the first layer. The applied metal layer is so thin that it is at least partially transparent for light. As metallic elements are basically all elements of the periodic table and

Elemental compounds attributable to the group of metals and compounds containing metallic elements. For example, the following metals are, for example, preferred: Al, Cr, Ni, Zn, Cu, Hg and Au.

In a simple, preferred embodiment of the invention

The security element decreases the transmission T (x, y) linearly or linearly through the second layer along at least one horizontal direction in the second layer (layer plane). The variation of the transmission T (x, y) in the second layer can, however, be defined according to the invention by any continuous function, with desirable optical effects being preferred for simple functions: linear

Functions, sine / cosine functions etc. occur. The transmission T (x, y) can vary in the range of 0-100%, preferably in the range of 30-100%, in particular in the range between 40-90%.

According to the invention, the security element for authenticating further comprises a luminescent material having, transparent to the light third layer, which is disposed on the opposite side of the first layer of the second layer, and which is photoconductively connected to the second layer, or at the first side of the first layer opposite second side of the first layer is arranged and is conductively connected to the first layer light. Light striking the third layer through the first and second layers excites the luminescent material present therein, the material being preferred is fluorescent to luminesce at a wavelength dependent on the material (dye). Due to the light-conducting connection, this luminescent light now passes from the third to the second layer and from the second to the first layer or from the third to the first layer and then further to the second layer. The luminescent light generated when looking at a viewer on the

Security element in turn dependent on the perspective color optical effect, which can not be imitated by a simple copy of the security element in a conventional copier. The achievable optical effects result from the interaction of the three layers of the invention

Security element.

Preferably, the third layer is directly on top of that of the first layer

arranged or applied opposite side of the second layer. In a preferred embodiment of the security element according to the invention, a motif is introduced into the third layer by targeted disruption of the layer's own total reflection. In this case, the term "motif" is understood broadly, in particular comprising any injectable, optically readable information, such as characters, images, barcodes, 2 or 3-dimensional codes, etc. For introducing the motif or motifs, in particular those described in DE 10 are suitable 2007 024 298 B3 disclosed methods, for example laser processing, laser engraving, steel embossing, intaglio printing etc.

Due to the disturbance of the layer's total reflection, the luminescent light is deflected at the introduced impurities. Preferably, the impurities are introduced so as to form a motif, i. represent an image, a signal code, or any one or more characters in the third layer. At the impurities, which ultimately reflect the motif, etc., the luminescent light is deflected out of the third layer in the direction of the second and first layer. Thus, depending on the optical effect produced by the structure of the first layer, the introduced motif etc. can be recognized by the viewer depending on the viewing angle.

In a further preferred embodiment of the invention

Security element is between the third layer and a layer composite consisting of the first layer and the second layer, one transparent to light Fourth layer is arranged, in which by targeted disruption of the layer's total reflection, a motif is introduced.

Of course, further layers, which are preferably completely transparent to the light, can be arranged between the aforementioned layer composite and the third layer. In particular, these may be adhesive layers, for example with a UV-curing adhesive. In particular, it is possible to arrange further fluorescent layers of different colors here.

In one embodiment, instead of the third layer, a combination of three layers each containing different fluorescent dyes is arranged. In this case, for example, the second layer (in the direction away from the first layer) preferably includes first a blue (B) fluorescent layer, then a green (G) fluorescent layer and finally a red (R) fluorescent layer. Special optical effects can be achieved by incorporating geometrically aligned motifs, etc. in all three fluorescent layers (B-G-R) described above, which complement each other to form an overall motif. In this case, introduced into the individual layers, superimposed in layers composite perturbations of the respective layer's total reflection, the overall motive color coded differently or light up, in particular create an impression of a white glow.

Further advantages, features and details of the invention will become apparent from the following description in which, with reference to the drawings, an embodiment is described in detail.

It shows:

1 is a schematic representation of a cross section of a security element according to the invention applied to a banknote in a first embodiment,

Fig. 2 Schematic representation of a cross section of a deposited on a banknote security element according to the invention in a second embodiment. FIG. 1 shows a schematic representation of a cross section along the x-axis 110 of a novel applied to a banknote 104

Security element for authenticating the banknote in one

Embodiment. In the present case, the y-axis is perpendicular to the image plane and extends into the image plane. The security element consists in the present case of three layers 01-103 and is applied to the third layer 103 on the banknote 104 so that a detachment of the security element would lead to the destruction of the banknote 104. The first layer 101 of the security element consists of a material with a refractive index ni and has on the underside 108 of the first layer 101 a structure 105, in this case the annular structure of a Fresnel lens on.

The second layer 102 of the security element is disposed below the first layer 101 directly on the structured surface 108 and consists of

Material with a (total) refractive index n ₂ , where n ₂ Φ n ^

in particular that n _{2 is} ni or n ₂ ni. Furthermore, the second layer 102 in the present case contains one or more metallic elements whose concentration in the

illustrated cross section through the security element, decreases from left to right, wherein the concentration distribution is selected such that the

Transmission T of the light through the second layer 02 according to a predeterminable continuous function T = T (x, y), in the present case a linear increase in the transmission in the direction of the x-axis from the left cross-sectional side to the right cross-sectional side, varies. In FIG. 1, the described varying concentration distribution C (x, y) is represented by the strip 109, in which the gray value decreases from left to right. Of course, the concentration distribution of the metallic elements may be locally constant over the thickness of the second layer, so that the following applies here: dC (x, y, z) dC (x, y, z) 8C (x, y, z)

= const. = o, = 0 where x, y, z

dx dz

are three-dimensional location coordinates in the second layer.

In the present case, a layer which contains copper or aluminum with a local concentration C (x, y) that varies one-dimensionally, ie, in the direction of the x-axis, is applied correspondingly to the structured surface 108, so that the transmission through the second layer changes linearly from left to right from a transmittance of 30% to 80% along the x-axis in the region of the structure 105.

The third light-transparent layer 103 in the present case has, for example, a red luminescent material, and is on the first layer 101

disposed opposite side of the second layer 102, and with the second layer 102 is light-conductively connected. Furthermore, a motif 06, for example a text, has been introduced into the third layer 103 by means of laser application by targeted disruption of the layer's own total reflection. If, for example, an observer looks at the upper side 107 of the security element in daylight, he sees the red glowing motif (text) in a supposed three-dimensional spherical space in a certain viewing angle area.

The security element described here allows depending on the selected

Structuring the bottom of the first layer 101, at the option of

Refractive index difference between the first and second layer, the choice of the variation of the areal transmission T (x, y) over the second layer 102, the choice of the luminescent material of the third layer 103, and after a

corresponding additional introduction of motifs or optical information into one of the three layers or into further between the second and third layer arranged light-conducting layers, the most diverse optical effects. The security element is largely forgery-proof and inexpensive to produce.

In particular, the structure 105 produces an optical effect, in particular

Magnifying effect, tilting effect, distortion effect, etc., when viewing the subject 106. Furthermore, the structure 105 as Lichtauskopplung a within the entire security element, in particular on the top 107, occurring total reflection act, so that the structure 105 additionally acts brighter than a surrounding area of the first layer 101, which is designed in particular plan, so has no structure.

FIG. 2 shows a schematic illustration of a cross section of a security element according to the invention applied to a banknote in a second embodiment. This second embodiment differs from FIG. 1 merely in that the arrangement of the layers 101 and 102 in the security element were exchanged. In this case, it is possible to provide the second layer 102, which then faces the viewer, with a protective layer, in particular in the form of a protective lacquer, which is preferably completely transparent to light. Otherwise, reference is made to the above description of FIG. 1.

LIST OF REFERENCE NUMBERS

101 first shift

102 second shift

103 third shift

104 banknote or general: object

105 structure

106 Motive, signs, optical information, etc. introduced by targeted disturbances of the layer's own total reflection

107 second side of the first layer

108 first page of the first layer

109 Schematic representation of an embodiment in which metallic elements are contained in the second layer whose concentration decreases in the illustrated cross section through the security element from left to right

10 x axis in the layer plane of the second layer

Claims

claims

1. security element for authentication, in particular of

Security documents, banknotes and similar objects,

characterized in that the security element comprises:

a light-transparent first layer (101) having a refractive index n-i, with a surface having a structure (105) on a first side (108) of the first layer (101),

a second layer (102) with a refractive index n ₂ arranged directly on the structured surface on the first layer (101), with the proviso that n is ₂ n- ₁ , in particular n ₂ »ni or n ₂ ni, and Transmission T of the light through the second layer (102) varies according to a predeterminable continuous function T = T (x, y) depending on the location in the second layer (102), and x and y

Are location coordinates in a layer plane of the second layer (102), and

a light-transparent third layer (103) having a luminescent material, which is arranged on the side of the second layer (02) opposite the first layer (101) and is conductively connected to the second layer (102), or the second side (107) of the first layer (101) which is opposite to the first side of the first layer (101) and is light-conductively connected to the first layer (101).

2. Security element according to claim 1,

characterized in that the second layer (102) contains metallic elements or is completely formed by metallic elements whose concentration C (x, y) varies in the layer plane in a location-dependent manner such that the transmission T corresponds to the function T = T (x, y ) varies.

3. Security element according to one of claims 1 to 2,

characterized in that the second layer (102) contains metallic elements or is completely formed by metallic elements, and the thickness D (x, y) of the second layer varies location-dependent in the layer plane such that the transmission T is given the function T = T (x, y) varies.

4. Security element according to one of claims 1 to 3,

characterized in that the security element has a thickness of <100 μητι, preferably <50 μητι, in particular 5-30 mm.

5. Security element according to one of claims 1 to 4,

characterized in that the light electromagnetic radiation

Wavelengths in the range of 1 nm to 1,000 nm.

6. Security element according to one of claims 1 to 5,

characterized in that the material is fluorescent.

7. Security element according to one of claims 1 to 6,

characterized in that the structure (105) has a concentric, elliptical, parallel, trapezoidal or star-shaped geometry.

8. safety element according to one of claims 1 to 7,

characterized in that the structure (105) comprises the annular step structure of a Fresnel lens.

9. Sicherheitsselemetlement according to one of claims 1 to 8,

characterized in that the structure (105) has the annular structure of a Fresnel zone plate.

10. Security element according to one of claims 1 to 9,

characterized in that the transmission T (x, y) of the second layer (102) decreases linearly at least in a horizontal direction of the second layer (102).

11. Film element according to one of claims 1 to 10,

characterized in that in the third layer (103) by targeted disruption of the layer's own total reflection, a motif (106) is introduced.

12. Film element according to one of claims 1 to 11,

characterized in that between the third (103) layer and a

Layer composite consisting of the first layer (101) and the second layer (102), a light transparent fourth layer is arranged, in which by targeted disruption of the layer's own total reflection a motif (106) is introduced.

13. Film element according to one of claims 1 to 12,

characterized in that the third layer (103) is disposed directly on the side of the second layer (102) opposite the first layer (101).