EP2838737A1

EP2838737A1 - Optically variable security element

Info

Publication number: EP2838737A1
Application number: EP13717173.2A
Authority: EP
Inventors: Annett Bähr; Michael Rahm; André Gregarek; Georg Depta; Walter DÖRFLER; Harald Reiner; Simon Freutsmiedl
Original assignee: Giesecke and Devrient GmbH
Current assignee: Giesecke and Devrient Currency Technology GmbH
Priority date: 2012-04-18
Filing date: 2013-04-16
Publication date: 2015-02-25
Anticipated expiration: 2033-04-16
Also published as: DE102012007747A1; AU2013248632A1; WO2013156149A1; AU2017200729A1; AU2013248632B2; CN104245346A; TWI574211B; IN2014KN02263A; TW201344588A; EP2838737B1; CN104245346B

Abstract

The invention relates to an optically variable security element (12) for security papers, documents of value and other data carriers, having a substantially transparent carrier (20) with first and second main surfaces (22, 24) located opposite one another, having an arrangement of microlenses (26) on the first main surface (22) of the carrier, having a laser-sensitive recording layer (30), which is arranged on the second main surface (24) of the carrier and contains first and second sub-layers (32, 34) arranged one above the other, wherein the first sub-layer (32) is arranged between the carrier (20) and the second sub-layer (34), and having a multiplicity of microholes (40) which are generated in the laser-sensitive recording layer by the action of laser radiation and of which each microhole (40) is assigned to a microlens (26) and, with the security elements being viewed from a certain viewing angle, can be seen through the associated microlens (26), wherein the multiplicity of microholes comprise a multiplicity of first and a multiplicity of second microholes (42, 44) wherein the first microholes (42) are present in the first sub-layer (32), and do not pass through the recording layer (30), and the second microholes (44) pass through the recording layer (30) with the first and second sub-layer (32, 34), and wherein the diameter of the first microholes (42) is larger than the diameter of the second microholes (44).

Description

Optically variable security element

The invention relates to an optically variable security element for security papers, value documents and other data carriers, a method for producing such a security element, and a data carrier with such a security element.

Data carriers, such as valuables or identity documents, but also other objects of value, such as branded articles, are often provided with security elements for the purpose of security, which permit verification of the authenticity of the data carrier and at the same time serve as protection against unauthorized reproduction. Security elements with viewing-angle-dependent effects play a special role in the authentication of authenticity since they can not be reproduced even with the most modern copiers. The security elements are thereby equipped with optically variable elements which give the viewer a different image impression under different viewing angles and, for example, show a different color or brightness impression and / or another graphic motif depending on the viewing angle.

For example, ID cards such as credit cards or identity cards have long been personalized by laser engraving. In personalization by laser engraving, the optical properties of the substrate material are irreversibly changed by suitable guidance of a laser beam in the form of a desired marking. Such a laser marking makes it possible to combine the individualization of the data carriers with security elements and to integrate them more freely into the print image than in conventional customizations, such as in known method of ciphers.

Document EP 0 219 012 A1 describes an identification card with a partial lens master structure. This lens structure inscribes information into the card at different angles with a laser. This information can then be detected only at this angle, so that when tilting the map, the different information appear.

Based on this, the present invention seeks to provide a security element of the type mentioned above with an attractive visual appearance and high security against counterfeiting. This object is solved by the features of the independent claims. Further developments of the invention are the subject of the dependent claims.

According to the invention, a generic security element comprises a substantially transparent support having opposing first and second major surfaces, an array of microlenses disposed on the first major surface of the support, a laser sensitive recording layer disposed on the second major surface of the support, first and second superimposed ones Contains partial layers, wherein the first partial layer is arranged between the carrier and the second partial layer, a plurality of microholes generated in the laser-sensitive recording layer by the action of laser radiation, each micro-hole being associated with a microlens and being visible from a given viewing angle through the associated microlens when the security element is viewed, the plurality of micro-holes being a plurality of first and a plurality second microholes, wherein the first microholes are in the first sublayer and do not pass through the recording layer, and the second microholes pass through the first and second sublayer recording layers, and wherein the diameter of the first microholes is larger than the diameter of the second microholes.

Microlenses are lenses whose size is below the resolution limit of the naked eye. The microlenses are preferably spherical or aspherical and have, for example, in banknotes with advantage a diameter between 5 μπι and 100 μιη, preferably between 10 μπι and 50 μπι, more preferably between 15 μιη and 20 μπι on. In card applications, the microlenses may also be larger and, for example, have a diameter between 100 μπι and 300 μιη. In all designs, the microlenses can also be designed as cylindrical lenses.

The diameter of the first microholes is preferably more than 10%, in particular more than 20%, and particularly preferably more than 30% larger as the diameter of the second microholes. However, the diameter of the first microholes is expediently not more than 4 times, in particular not more than 3 times, the diameter of the second microholes. Due to the magnification effect of the microlenses, even a slight difference in the hole size of the first and second microholes leads to a good contrast difference of the incident light or transmitted light eff ect, as explained in more detail below.

In expedient embodiments, the diameter of the second microholes is between 2 .mu.m and 4 .mu.m and the diameter of the first microholes is between 3 .mu.m and 8 .mu.m. For a good contrast difference, the diameters of the first micro-holes, for example, 0.5 μιη to 4 μιη greater than the diameter of the second microholes. In advantageous embodiments, the microholes are each smaller than the associated microlenses. The area ratio of micro-wells and associated microlens may be below 1.0 or below 0.5, below 0.2, or even below 0.1.

In simple configurations, the first and second microholes are each formed substantially circular or linear. However, it is also possible to form the first and / or second microholes in a pattern shape, for example in geometric shapes such as squares, triangles or stars, or in the form of microcharacters such as letters, numbers or the like, to provide an additional, hidden security feature in the security element to integrate. A pattern-shaped training is especially suitable for the larger first microholes. While the first microholes differ at least in size and possibly also in their shape from the second microholes, the first microholes themselves advantageously all have the same shape and size, as do the second microholes.

Advantageously, the first microholes form a first motif in the form of patterns, characters or a code that is recognizable when the security element is viewed from a preselected first viewing direction, and the second microholes form a second motif in the form of patterns, characters or an encoding. which can be seen in the case of transmitted light viewing of the security element from a preselected second viewing direction. The first and second motif are usually different but may be identical. The first and second viewing directions are preferably different, but may also be identical.

In advantageous configurations, the first and second microholes are arranged independently of each other. In other equally advantageous designs, at least a portion of the second microholes lie entirely within the first microholes. For example, more than 50%, more than 75%, or even all second microholes may be completely within the first microholes. In this way, a "motif in the subject" can be generated, in which a transmitted light motif appears within an incident light motif, for example, the security element can contain a visible in incident light coat of arms, which is formed by the first microholes and in the interior when changing to the transmitted light viewing a logo is visible, which is formed by the second microholes In this case, the first and second viewing direction are suitably selected identically. The first and / or second microholes are introduced in appropriate embodiments from different directions with laser radiation through the microlens arrangement into the recording layer. In the later consideration, the microholes are then from the respective viewing direction, from which they were introduced, in reflected light or

Transmitted light visible. In this case, as already described above, the first microholes may each be recognizable from a first viewing direction and the second microholes may each be recognizable from a second, different viewing direction.

However, it is also possible that a group of first microholes is introduced from one direction, another group of first microholes from another direction. The first motif formed by the first microholes then shows a tilting or alternating image whose partial images are formed by the different groups of first microholes. Embodiments with more than two introduction directions or continuous changes of direction are also possible. Alternatively or additionally, the second microholes may be introduced from two or more different directions in the same way.

The motif parts or partial images that are visible from different viewing directions can be in a sense context and, for example, represent a sequence of images that proceeds in front of the eye of the observer when the security element is tilted, as in a flip-book. If the angle of insertion and hence the viewing angle changes continuously, the degree of transparency changes, and thus the brightness in which the motif appears when the security element tilts, changes continuously. The first and second sublayers of the recording layer are advantageously formed by metal layers, for example by layers of aluminum, copper, silver, gold, chromium, nickel, tungsten, palladium or an alloy of these metals, such as an Al-Cu alloy. Advantageously, the first and second sub-layers are formed by metal layers of different colors, such as aluminum and copper. In order to ensure a particularly good visibility of the incident light motif, the second sub-layer is advantageously formed by a highly reflective metal layer having a reflectivity of 90% or more, for example by a vapor-deposited aluminum or silver layer.

The first and / or second sub-layer is advantageously opaque, wherein a layer is called opaque if its transmission in the visible is less than 1%, in particular less than 0.1%.

In advantageous embodiments, the recording layer consists of the first and second sub-layers, ie contains no further layers.

However, embodiments are also conceivable in which one or more further layers are arranged between the first and the second partial layer of the drawing layer. In particular, one or more layers transparent to the laser, for example dielectric layer (s) of SiC ₂ (silicon dioxide), may be present between the first and second part-layers. Such additional layers can be used, for example, to produce a certain color and / or color-shift effects, and / or serve as an adhesion-enhancing layer (s). In addition, the sub-layers as such each consist of several individual layers, which may also contain neutral layers. As will be explained in detail below, the difference in diameter or area of the microholes in the same recording layer allows two distinct appearances of the security element to be coded for incident and transmitted light viewing. Briefly summarized, a viewer looks at the high-reflecting second partial layer while viewing the incident light through the comparatively large first microholes, while the smaller second micro-holes are not recognizable, especially due to their small size in incident light. Due to the high reflectivity of the second sub-layer, the first motif formed by the first micro-holes is therefore clearly visible in incident light, while the second motif remains hidden.

In transmitted light, sufficient light also falls through the comparatively small second microholes in order to be able to recognize the second motif formed by them, while the first motif remains hidden from the first microholes present in the first sublayer because of the opacity of the second sublayer.

The first microholes present in the first partial layer preferably do not extend into the second partial layer. However, if the first and second sub-layers lie directly above one another, it is harmless in practice if the holes extend slightly into the second sub-layer, ie, less than 1/10 or even less than 1/20 of the layer thickness due to production. All that is essential is that the remaining layer thickness of the second partial layer has a sufficiently high reflectivity and a sufficiently high opacity.

In an advantageous development of the invention, the security element also contains a micro-optical representation arrangement, in particular a Moire magnification arrangement, a Moir micro-optical magnification arrangement or a modulo magnification arrangement. The basic principle of such micro-optical representational arrangements is explained in the publication WO 2009/000528 A1, the disclosure of which is incorporated into the present description to this extent. In this case, the security element preferably has a motif image between the carrier and the recording layer, which is divided into a plurality of cells, in each of which imaged regions of a predetermined background motif are arranged, wherein the microlens array forms a microlens raster which, viewed on the motif image, forms the image Background motif reconstructed from the mapped areas arranged in the cells.

The motif image is advantageously in the form of a relief structure in an embossing lacquer layer arranged between the support and the recording layer. In this case, provision can be made in particular for the first and second partial layers to follow the relief of the embossing lacquer layer, ie to have substantially the same relief structure.

In one variant of the invention, the microlens array can be provided with a semitransparent cover layer and / or a cover layer present only in regions. However, it is presently preferred for the microlens array to be free of applied layers which impair or cancel out the optical effect of the microlenses.

The invention also includes a data carrier, in particular a value document, such as a banknote, a passport, a document, an identity card or the like, which is equipped with a security element of the type described. The security element can, in an advantageous inventive variant in particular be arranged in or over a window area or a through opening of the data carrier.

The invention further includes a method for producing an optically variable security element for security papers, value documents and other data carriers, in which a substantially transparent support is provided with opposing first and second major surfaces, wherein an arrangement of microlenses is arranged on the first main surface of the support is arranged on the second main surface of the carrier, a laser-sensitive recording layer containing superimposed first and second sub-layers, wherein the first sub-layer is disposed between the carrier and the second sub-layer, in the laser-sensitive Auf drawing layer by the action of laser radiation, a plurality of micro-holes each micro-hole is associated with a microlens and is visible from a particular viewing angle through the associated microlens upon viewing the security element, the plurality of Microholes include a plurality of first and a plurality of second microholes, wherein the first microholes are continuously formed in the first sublayer and not by the recording layer, and the second microholes are formed through the first and second sublayer recording layers; the first micro-holes are made with a larger diameter than the second micro-holes. In an advantageous development of the method, the first and / or second microholes are introduced from different directions with laser radiation through the microlens array into the recording layer. In an advantageous variant of the method, only the first part-layer of the laser-sensitive recording layer is initially produced on the second main surface of the support in a first step and provided with the multiplicity of first microholes by the action of laser radiation. In a second step, the second sub-layer of the laser-sensitive recording layer is then arranged on the first sub-layer, and the second micro-holes are produced through the recording layer with first and second sub-layers.

Contains another optically variable security element for security papers, value documents and other data carriers

a substantially transparent support having opposite first and second major surfaces,

an arrangement of microlenses arranged on the first main surface of the carrier,

a laser-sensitive recording layer arranged on the second main surface of the carrier, in particular a metal layer,

a printing layer arranged on the recording layer, in particular a color layer, a plurality of micro-holes formed in the laser-sensitive recording layer by the action of laser radiation, each micro-hole being associated with a microlens and being visible from a particular viewing angle through the associated microlens when viewing the security element, each micro-hole being smaller than the associated microlens;

at least one gap region generated in the recording layer by the action of laser radiation, the dimension of which is greater than the dimension of the microlenses,

wherein the at least one gap region forms a first motif in the form of patterns, characters or a code, which is recognizable in the incident light observation and transmitted light observation of the security element with the appearance of the print layer, and

wherein the microholes form a second motif in the form of patterns, characters or a coding, which is recognizable only in case of transmitted light observation of the security element from a preselected viewing direction and complements from this viewing direction with the first motif to a total motif.

The at least one gap region forms a macroscopic motif visible to the naked eye, in particular without magnification by the microlenses. Its smallest dimensions are usually above 0.5 mm, typically at a few millimeters. The material of the print layer may but need not penetrate into the microholes and / or the gap areas. Preferably, the microlens array is free of deposited layers that affect or cancel the optical effect of the microlenses. The recording layer may be, for example, a 50 nm thick aluminum layer, for example, the printing layer may be an imprinted solvent-based red lacquer coating. layer. The security element can be applied to a data carrier with a certain transparency in transmitted light, such as banknote paper. In advantageous embodiments, the security element is arranged in or above a window area or a through opening of a data carrier.

Further exemplary embodiments and advantages of the invention will be explained below with reference to the figures, in the representation of which a representation true to scale and proportion has been dispensed with in order to increase the clarity.

a schematic representation of a banknote with an optically variable security element according to the invention, which is arranged over a continuous opening of the banknote, schematically the layer structure of a security element according to the invention in cross section, in (a) and (b) two intermediate steps in the production of the security element of FIG 2 shows the visual appearance of the security element of FIG. 2 viewed from the front side, wherein (a) and (b) show the appearance of two viewing directions in reflected light, and (c) and (d) show the appearance of two viewing directions in transmitted light. and 5 shows the visual appearance of the security element of FIG.

2 when viewed from the back, in (a) in reflected light and in (b) in transmitted light. The invention will now be explained using the example of security elements for banknotes. FIG. 1 shows a schematic illustration of a banknote 10 with an optically variable security element 12 according to the invention, which is arranged above a continuous opening 14 of the banknote 10. The security element 12 appears semitransparent in partial regions as a function of the direction of transparency and, due to its application over the opening 14, can be viewed both from its front side and from its rear side both in reflected light and in transmitted light. The security element 12 shows in each case different visual appearances from these different viewing directions, which leads to a high attention and recognition value.

Figure 2 shows schematically the layer structure of the security element 12 according to the invention in cross section, wherein only the parts of the layer structure required for the explanation of the functional principle are shown.

The security element 12 includes a substantially transparent support 20, which is typically formed by a transparent plastic film, for example, about 20 μιη thick polyethylene terephthalate (PET) film. The carrier 20 has opposite first and second main surfaces, wherein the first main surface 22 is provided with an arrangement of microlenses 26. In the exemplary embodiment shown, the microlenses 26 are regularly arranged in the form of a microlens grid and form a two-dimensional Bravais lattice with a preselected symmetry on the surface of the carrier foil. The Bravais grid of microlenses 26 can For example, have a hexagonal lattice symmetry or lower symmetry, such as the symmetry of a parallelogram grating. The spherically or aspherically configured microlenses 26 preferably have a diameter between 15 μm and 30 μm in the exemplary embodiment and are therefore invisible to the naked eye. The thickness of the carrier 20 and the curvature of the microlenses 26 are matched to one another such that the focal length of the microlenses 26 substantially corresponds to the thickness of the carrier 20.

On the second main surface 24 of the carrier 20, a laser-sensitive recording layer 30 is arranged, which consists of two superposed sub-layers, wherein the first sub-layer 32 is disposed between the carrier 20 and the second sub-layer 34. Preferably, the first and second sub-layers 32, 34 are formed of metal layers of different colors and the second sub-layer has a particularly high reflectivity of 90% or more. In the exemplary embodiment shown, the first sub-layer 32 is formed by a copper layer 100 nm thick and the second sub-layer 34 by a 50 nm thick aluminum layer, which were vapor-deposited successively on the carrier 20.

Further, a plurality of circular microholes 40 were introduced into the recording layer 30 by the action of laser radiation. A part of the microholes (hereinafter referred to as first microholes 42) is present only in the first part-layer 32 and does not pass through the recording layer 30. Another part of the microholes (hereinafter called second microholes 44) passes through the recording layer 30 having the first and second sub-layers 32, 34. The plurality of first microholes 42 together form a first motif 46, in the exemplary embodiment the logo "G + D", which is recognizable when viewing the security element from a preselected first viewing direction (Figure 4 (b)) together forms a second motif 48, in the exemplary embodiment the pair of letters "PL", which is recognizable by a reflection of transmitted light of the security element from a preselected second viewing direction (FIG. 5 (b)). The first microholes 42 have a diameter of 6 μπι, the second microholes a diameter of only 4 μπι on. The diameter of the first microholes 42 is therefore (6μπι / 4μιη) = 1.5 times the diameter of the second micro holes 44. The surface of the first micro holes 42 is correspondingly (6 μηι / 4 μηπ) ² = 2.25 times As a result, on the one hand, only the first motif 46, but not the second motif 48, is visible in incident light. On the other hand, the large first microholes 42, combined with the high reflectivity of the second sublayer 34, ensure a bright appearance of the first motif.

The visibility of the first and second motifs only from certain preselected viewing directions is a direct consequence of the generation of the microholes through the microlenses 26. With reference to FIG. 3, to produce the security element 12 on the second main surface of the carrier 20, first a 100 nm thick copper layer 32 is applied and to this a 50 nm thick aluminum layer 34, preferably in a vacuum vapor method. At these layer thicknesses, both the copper layer 32 and the aluminum layer 34 are opaque. The aluminum layer 34 also has a particularly high reflectivity of more than 90%. The coated carrier is then exposed from the side of the microlenses 26 from the desired later viewing direction 50 of the second motif with laser radiation, for example with the radiation of an Nd: YAG, NdiYVCv or fiber laser. The microlenses 26 f focus the laser radiation onto the recording layer 30, as indicated by the reference numeral 52 in FIG. 3 (a). The laser energy or laser power is chosen so that both the first sub-layer 32 and the second sub-layer 34 is removed, so that through the recording layer continuous, circular second micro holes 44 having a diameter of 2 to 4 μπι arise. The laser beam travels the surface of the second motif 48, so that the entirety of the second microholes 44 forms the second motif 48. Then the coated carrier is in turn subjected to laser radiation from the side of the microlenses 26 from the desired later viewing direction 54 of the first motif. The microlenses 26 f focus the laser radiation onto the recording layer 30, as indicated by the reference numeral 56 in FIG. 3 (b). In the case of laser energy or laser power, this step is chosen so that essentially only the first partial layer 32, but not the second partial layer 34, is removed. For example, to create the larger area of the first microholes 42, the irradiation direction of the small amplitude laser may be circularly tilted about the desired viewing direction 54. In this way, circular first microholes are produced with a diameter of 3 to 8 μιη. The laser beam also travels the surface of the first subject 46 so that the entirety of the first microholes 42 forms the first subject 46. By means of this procedure, it is achieved that each of the microholes 42, 44 is assigned a microlens 26, by which the microhole 42, 44 is generated when the laser is applied, and by which the microhole becomes visible due to the reversibility of the beam path during the later viewing of the security element is.

In an alternative method variant, not shown here, to produce the security element 12, a 100 nm-thick copper layer 32 is first applied to the second main surface of the carrier 20, preferably in a vacuum vapor method. The carrier coated with the copper layer 32 is then exposed from the side of the microlenses 26 from the desired later viewing direction 54 of the first motif to laser radiation, for example to the radiation of an Nd: YAG, Nd: YV04 or fiber laser. The microlenses 26 focus the laser radiation on the first sub-layer 32. The laser energy or laser power is chosen so that the first sub-layer 32 is removed and circular first micro-holes are produced with a diameter of 3 to 8 μιη. For example, to create the larger area of the first microholes 42, the irradiation direction of the small amplitude laser may be circularly tilted about the desired viewing direction 54. The laser beam travels the surface of the first motif 46, so that the entirety of the first microholes 42 forms the first motif 46.

Subsequently, a 50 μm thick aluminum layer 34 is applied to the copper layer 32, preferably vapor-deposited. The coated carrier is then exposed from the side of the microlenses 26 forth from the desired later viewing direction 50 of the second motif with laser radiation. The microlenses 26 focus the laser radiation onto the recording layer 30. The laser energy or laser power is chosen in this case, in that both the first partial layer 32 and the second partial layer 34 are removed so that continuous, circular second microholes 44 (having a diameter of 2 to 4 μm) are formed through the entire recording layer 30. In this case, the laser beam cuts off the surface of the second motive 48 so that the entirety of the second microholes 44 forms the second motive 48.

FIG. 4 shows the visual appearance of the security element 12 thus produced when viewed from the side of the first main surface 22 (front side), wherein FIGS. 4 (a) and 4 (b) of the appearance consist of two viewing directions in reflected light, ie in reflection 4, and FIGS. 4 (c) and 4 (d) show the appearance from two viewing directions in transmitted light, ie in transmission. In reflected light, a viewer looks from the viewing direction 54 (FIG. 3 (b)) through the microlenses 26 to the microholes 42 of the first sub-layer 32 and thus to the underlying second sub-layer 34. Because of the high reflectivity of the second sub-layer 34 and the comparatively large Surface of the first microholes 42 is visible from direction 54, the first motif (logo "G + D") bright and with good contrast silver against the copper-colored background of the first sub-layer 32, as shown in Fig. 4 (b).

From another viewing direction, which does not correspond to the preselected viewing direction 54 of the first motif, the first microholes 42 are not visible in reflected light, since in this case the viewer passes through the microlenses 26 to a position of the first sublayer lying outside the microholes 42 32 is looking. The second micro holes 44 are less conspicuous or not at all due to their much smaller area in reflected light to recognize. Overall, the security element 12 thus appears from such a viewing direction as a homogeneous, copper surface, as shown in Fig. 4 (a). By reciprocating the security element 12, the observer can change between the appearances of FIGS. 4 (a) and 4 (b) in incident light.

In transmitted light, the recording layer 30 is semitransparent through the plurality of second micro holes 44, depending on the direction of view. Since the micro-holes 44 are viewed through the microlenses 26 in this viewing direction, the light incident from the backside each appears to be substantially at the angle through the microholes 44 in which they were introduced when generated by the laser beam. Therefore, from the viewing direction 50 (Fig. 3 (a)), the second motif formed by the second microholes (letter sequence "PL") is brightly visible in transmission against the dark background of the metallic recording layer 30, as shown in Fig. 4 (d).

From a different viewing direction, which does not correspond to the preselected viewing direction 50 of the second motif, the second microloads 44 are not visible in transmitted light, since in this case the viewer passes through the microlenses 26 to a position of the first or the third outside of the microholes 44 second sub-layer looks. Both the first and second sub-layers are opaque, such that the security element 12 appears as a homogeneous, dark area from such a viewing direction, as shown in FIG. 4 (c). By reciprocating the security element 12, the viewer can change in the transmitted light between the appearances of FIGS. 4 (c) and 4 (d). The different appearance in reflected light and transmitted light is unusual and surprising for a viewer and therefore leads to a visually attractive and eye-catching overall impression with high attention and recognition value.

Figure 5 shows the visual appearance of the security element 12 as viewed from the side of the second major surface 24 (back), with Figure 5 (a) illustrating the appearance in reflected light and Figure 5 (b) illustrating the appearance in transmitted light.

In reflected light, only the silver-colored second sub-layer 34 can be seen from the rear, since the continuous second micro-holes 44 can not be recognized due to their small size in reflected light. The observer therefore sees the homogeneously silver-colored metal layer 34 in reflected light from the rear side, as illustrated in FIG. 5 (a).

When viewed in transmitted light, the security element 12 appears semitransparent due to the multiplicity of second microholes 44 in a large angular range. In contrast to the viewing from the front side, the second microholes 44 are not viewed by microlenses 26 in the rear-side view. Rather, the microlenses 26 collect the light incident from the first major surface 22 and focus on the second microholes 44 to provide a wide range of angles below which the second motif 48 formed by the microholes 44 appears bright from the rear.

The first microholes 42 do not pass through the on-drawing layer 30, so that the first motif 46 is not recognizable from the rear, even in transmitted light, because of the opaque second sub-layer 34. All in all Thus, in a wide range of angles, the observer sees the brightly glowing letter "PL" against a dark background, as illustrated in Fig. 5 (b). "" As the second subject appears mirrored when viewed from the rear side, the second subject is preferably a mirror symmetry - selected motif, or a mirror-neutral motif, ie a motif whose recognisability is not affected by the reflection, such as a geometric pattern, an architectural, technical or nature motif.

In one variant, the insertion angle and thus also the viewing angle of the first and / or second microholes can be varied continuously over the extent of the first or second motif 46, 48 in one or even in two spatial directions. Such a continuous variation can be realized for example by a suitable deflection system for the laser radiation. The brightness of the first or second motif 46, 48 then changes continuously when viewed in reflected light or transmitted light when tilting the security element.

LIST OF REFERENCE NUMBERS

bill

security element

opening

carrier

, 24 main surfaces

microlenses

Recording layer, 34 first and second sub-layers, respectively

Microholes, 44 first and second microholes, 48 first and second motif, respectively

Viewing direction focused laser radiation

Claims

Patent claims

1. Optically variable security element for security papers, value documents and other data carriers with

a substantially transparent support having opposing first and second major surfaces,

a laser-sensitive recording layer arranged on the second main surface of the carrier and comprising first and second partial layers arranged one above the other, the first partial layer being arranged between the carrier and the second partial layer,

a plurality of microholes generated in the laser-sensitive recording layer by the action of laser radiation, each micro-hole being associated with a microlens and being visible through the associated microlens when viewing the security element from a given viewing angle,

wherein the plurality of microholes includes a plurality of first and a plurality of second microholes, the first microholes being in the first sublayer and not passing through the recording layer and the second microholes passing through the first and second sublayer recording layers;

the diameter of the first microholes is larger than the diameter of the second microholes.

2. The security element according to claim 1, characterized in that the diameter of the first microholes is more than 10%, in particular more than 20%, and particularly preferably more than 30% greater than the diameter of the second microholes.

3. Security element according to claim 1 or 2, characterized in that the first microholes form a first motif in the form of patterns, characters or a coding, which is recognizable in reflected light observation of the security element from a preselected first viewing direction, and the second microholes a second motif form in the form of patterns, characters or a coding, which is recognizable in transmitted light observation of the security element from a preselected second viewing direction.

4. The security element according to claim 1, wherein the first and / or second microholes are introduced into the recording layer from different directions with laser radiation through the microlens array and the microholes, when viewed from the respective viewing direction in FIG Incident light or transmitted light can be seen.

5. The security element according to at least one of claims 1 to 4, characterized in that the first and second microholes are each substantially circular or musterf örmig.

6. Security element according to at least one of claims 1 to 5, characterized in that the micro-holes are each smaller than the associated microlenses.

7. The security element according to at least one of claims 1 to 6, characterized in that the area ratio of microholes and associated microlenses below 1.0 or below 0.5 or even below 0.2.

8. The security element according to at least one of claims 1 to 7, characterized in that more than 50%, preferably more than 75% of the second microholes lie within the first microholes.

9. Security element according to at least one of claims 1 to 8, characterized in that the first and second sub-layers are formed by metal layers of different colors.

10. The security element according to at least one of claims 1 to 9, characterized in that the second sub-layer is formed by a highly reflective metal layer with a reflectivity of 90% or more.

11. The security element according to at least one of claims 1 to 10, characterized in that the first and / or second sub-layer is opaque.

12. A security element according to at least one of claims 1 to 11, characterized in that between the carrier and the recording layer, a motif image is provided, which is divided into a plurality of cells, in each of which imaged areas of a predetermined background motif are arranged, wherein the microlens array a Mikrolinsenras - ter forms, which reconstructs the background motif from the imaged areas arranged in the cells when viewing the motif image.

13. A security element according to claim 12, characterized in that the motif image is present as a relief structure in a marking layer between the carrier and on Auflagschichtschicht arranged.

14. The security element according to claim 13, characterized in that the first and second partial layer follow the relief of the embossing lacquer layer.

15. The security element according to claim 1, characterized in that the microlens arrangement is provided with a semitransparent cover layer and / or a cover layer present only in regions.

16. The security element according to claim 1, characterized in that the microlens arrangement is free of layers applied on it which impair or cancel the optical effect of the microlenses.

17. A data carrier with a security element according to at least one of claims 1 to 16.

18. A data carrier according to claim 17, characterized in that the security element is arranged in or over a window area or a through opening of the data carrier.

19. A method for producing an optically variable security element for security papers, value documents and other data carriers, wherein a substantially transparent support is provided with opposite first and second major surfaces, wherein on the a laser-sensitive recording layer is arranged on the second main surface of the carrier, the first and second sub-layers arranged one above the other, wherein the first sub-layer is arranged between the carrier and the second sub-layer, in which laser-sensitive recording layer is generated by the action of laser radiation, a plurality of micro-holes, each micro-hole of a microlens and is visible when viewing the security element from a certain viewing angle through the associated microlens, - wherein the plurality of microholes a plurality of first and a plurality second microholes, wherein the first microholes are continuously formed in the first sub-layer and not by the recording layer, and the second micro-holes are passed through the recording layer having first and second sub-layers can be generated, and wherein the first microholes are produced with a larger diameter than the second microholes.

20. The method according to claim 19, characterized in that the first and / or second microholes are introduced from different directions with laser radiation through the microlens array into the recording layer.

21. The method according to claim 19 or 20, characterized in that on the second main surface of the carrier in a first step, only the first sub-layer of the laser-sensitive recording layer is generated and hen by the action of laser radiation with the plurality of first micro holes verse- hen, and in a second Step, the second sub-layer of the laser-sensitive recording layer is disposed on the first sub-layer, wherein the second micro-holes are formed through the recording layer having first and second sub-layers.