EP3820713B1 - Optically variable security element having reflective surface region - Google Patents

Description

The invention relates to an optically variable security element for protecting objects of value with a flat carrier and a reflective surface area arranged on the carrier. The invention also relates to a method for producing such a security element and to a data carrier equipped with such a security element.

Data carriers, such as value or ID documents, but also other valuables, such as branded items, are often provided with security elements for protection, which allow the authenticity of the data carrier to be checked and which also serve as protection against unauthorized reproduction. The security elements can be designed, for example, in the form of a security thread embedded in a banknote, a cover film for a banknote with a hole, an applied security strip, a self-supporting transfer element or also in the form of a feature area printed directly onto a document of value.

Security elements with a viewing angle-dependent or three-dimensional appearance play a special role in authenticity protection, as these cannot be reproduced even with the most modern copiers. For this purpose, the security elements are equipped with optically variable elements that give the viewer a different image impression from different viewing angles and, for example, show a different color or brightness impression and/or a different graphic motif depending on the viewing angle. The prior art describes, for example, movement effects, pump effects, depth effects or flip effects as optically variable effects, which are realized with the aid of holograms, microlenses or micromirrors.

It is known to produce a simple colored surface using a diffractive structure, but the color produced by the diffractive structure is dependent on the viewing angle. A grid of opaque elements placed an appropriate distance above the diffractive structure can be used to reduce the viewing angle dependence of color.

DE102007034716A1 relates to a multi-layer security element with translucent and opaque sections. WO 97/19820 A1 shows an optical Information carrier with two optically effective structures, which are arranged in different planes and which together produce a characteristic optical effect. DE 102007061827 A1 relates to a security element with an embossing layer over which a thin-layer element with a color-shift effect is arranged. The surface extent of the security element defines a z-direction perpendicular to the surface. Are shown in a

Figure two relief structures, which are arranged in the z-direction at different height levels. However, the total of three layers of the thin-film element each follow the relief structure of the embossed layer. No color shift effect is discernible in the area of gaps in the absorber layer of the thin-film element. A semi-transparent color layer is arranged over the thin-film element in the area of the recesses. When viewed under predetermined viewing conditions, the color impression of the thin-film element is adapted to the color impression of at least a partial area of the semi-transparent color layer.

Proceeding from this, the object of the invention is to further increase the security against forgery and the visual attractiveness of generic optically variable security elements and in particular to provide optically variable security elements with two or more different appearances or effects in different colors.

This object is solved by the features of the independent claims. Developments of the invention are the subject matter of the dependent claims.

The optically variable security element includes a multicolored, reflective surface area. The surface extent of the security element defines a z-direction perpendicular to the surface. The multicolored, reflective surface area contains two relief structures that are arranged at different height levels in the z-direction. The relief structures are each provided with a color coating that creates a different color impression. The two relief structures also overlap in a feature area.

The color coating of the higher-lying relief structure in the feature area is present as a regular or irregular grid with grid elements and grid spaces is formed. The dimensions of the grid elements and/or the gaps between the grids are less than 140 μm, at least in one direction. In the feature area, the color coating of the lower-lying relief structure appears to an observer from at least one viewing angle through the raster interstices of the color coating of the higher-lying relief structure.

In an advantageous embodiment, the grid elements and grid spaces of the grid have the same shape and preferably also the same size. The grid elements and/or the gaps between the grids can be formed in particular by strip-shaped, square, triangular or other polygonal elements, but can also have irregular shapes. The grid itself can be regular, i.e. have a regular arrangement of grid elements and grid spaces, but can also be an irregular grid, for example a stochastic grid, in which the grid elements and/or grid spaces have irregular spacing and/or sizes and/or shapes.

The area coverage of the grid by the grid elements is advantageously between 30% and 70%, preferably between 40% and 60%, in particular around 50%. The area coverage of the grid and the brightness of the color coatings are advantageously matched to one another in order to produce essentially the same brightness of the color coating of the higher-lying relief structure and the color coating of the lower-lying relief structure, which appears through the interstices of the grid. By choosing the area coverage, however, different bright color impressions of the two color coatings can also be generated in a targeted manner.

The grid elements and/or grid spaces can each represent separate elements or also form a coherent structure. Preferably, the dimensions of both the grid elements and the gaps between the grids are less than 140 μm, at least in one direction. In particular, the dimensions of the grid elements and/or the gaps between the grids are preferably in one or both lateral directions between 20 μm and 140 μm, preferably between 40 μm and 120 μm, in particular between 60 μm and 100 μm.

The relief structures are preferably embossed structures. In particular, embossing in a hardenable layer, such as UV lacquers, for example, is further preferred. Alternative production methods, such as subtractive lasering or additive construction, for example using 3D printing, are conceivable but less cost-effective.

The relief structures of the multicolored reflective surface area together with the color coating in the feature area preferably form monochromatic reflective relief structures. The multicolored reflective surface area is preferably a two-colored reflective surface area. The security element can comprise a number of different two-colored reflective surface areas. The additional (or the additional) reflective surface area(s) can in particular be present adjacent to, surrounding or spaced apart from the multicolored reflective surface area described up to now. In further configurations, the security element can contain an additional, differently two-colored, feature area or several additional, each differently two-colored, feature areas. The additional feature area can (or the additional feature areas can) in particular be present adjacent to, surrounding or spaced apart from the feature area described so far.

The color coating of the higher-lying and/or lower-lying relief structure appears in the present case in particular only as a function of the viewing angle. When viewed in the z-direction, the color coating of the higher-lying and/or lower-lying relief structure does not appear. The color coating of the lower-lying (and higher-lying) relief structure appears colored reflective at the viewing angle. At the viewing angle, the light is reflected from this relief structure to the viewer and thus appears in the present sense, with the color coating determining the color impression. Since the incoming light also has a preferred direction--in particular essentially perpendicular--a clearly perceptible colored light reflex is produced for the viewer, as is known.

The upper relief structure and its color coating could alternatively be referred to as the first (or upper) relief structure and first (or upper) color coating and the lower relief structure and its color coating as the second (or lower) relief structure and second (or lower) color coating.

In configurations it is provided that in a part of the feature area (or the entire feature area) either the color coating of the higher-lying relief structure or the color coating of the lower-lying relief structure appears for the observer depending on the viewing angle. Thus, either the first color impression of the first (or upper) color coating or the second color impression of the second (or lower) color coating arises in the part of the feature area—only alternatively, but not at the same time. A first viewing angle range in which the underlying color coating appears, and a second viewing angle range, in which the higher-lying color coating appears, do not overlap, preferably adjoin one another. In an optional third viewing angle range, neither of the two color coatings appear for the viewer. The size of the third viewing angle range is advantageously greater than the sum of the sizes of the first and second viewing angle range.

In a further part of the feature area, both color coatings can be visible to the viewer from at least one viewing angle at the same time, in particular appear at the same time at one viewing angle or be visible independently of the viewing angle. The viewer sees the other part in a mixed color tone.

Furthermore, the feature area is preferably designed in such a way that, at the viewing angle, the (second) color coating of the lower-lying relief structure appears in a first part of the feature area, and the color coating of the higher-lying relief structure (or neither of the two color coatings) appears in a second part of the feature area ) appears. In an optional third part of the feature area, neither of the two color coatings (or the color coating of the higher relief structure) will appear at the same time.

Depending on the viewing angle, the two relief structures can provide the color change for an unchanged motif or provide the color change together with a motif change. The motifs of the two relief structures can differ in particular in terms of shape (e.g. heads, apples or numbers), movement (static to moving or moving to moving - with linear, rotating and/or pumping movement) and/or three-dimensionality (two-dimensional to three-dimensional or different three-dimensional - with a positively or negatively curved appearance and/or floating in front of or behind a plane). It is known per se to produce such motifs and certain motif changes with the aid of relief structures.

In an advantageous embodiment, it is provided that the higher-lying relief structure generates a first motif with a first color impression, which is visible from a first viewing angle range, and the lower-lying relief structure generates a second motif with a second, different color impression, which is visible from a second viewing angle range is, wherein the first and second viewing angle range do not overlap. When tilted, the security element then shows a binary color and effect change without an overlapping area. The two viewing angle ranges preferably border one another or are only separated by an angular distance of a few degrees, so that the associated image impressions change as seamlessly as possible for the viewer. The first and second motif can also be identical, so that when the motif is tilted there is only a binary color change.

• zueinander versetzt bewegen oder gegeneinander bewegen und sich dabei in einer Überscheidungsstellung, in der beide Bewegungsmotive sichtbar sind, kreuzen und/ oder
• nacheinander durch denselben Teil des Merkmalsbereichs bewegen.

In another, likewise advantageous embodiment, it is provided that the higher-lying relief structure generates a first movement motif with a first color impression and the lower-lying relief structure generates a second movement motif with a second, different color impression, with the first and second movement motif changing when the security element is tilted

• move offset to each other or move against each other and thereby cross and/or in an overlapping position in which both movement motifs are visible
• sequentially move through the same part of the feature space.

In the case of a movement motif, a part of the motif moves when it is tilted, for example a bright bar across the motif area. The part of the motif can move linearly or along a curved path and can also change its shape and size during the movement, for example with so-called pump or morph effects.

• Ein binärer Motivflip zwischen gewölbten und/ oder dreidimensional erscheinenden Bildmotiven mit binärem Farbwechsel. Ein erster Betrachtungswinkelbereich erstreckt sich beispielsweise von +5° bis +20° bezogen auf eine Flächennormale des Sicherheitselements, ein zweiter Betrachtungswinkelbereich von -5° bis -20°. Das erste und zweite Motiv können auch identisch sein, so dass sich ein reiner binärer Farbwechsel ergibt.
• Pump- oder Laufeffekte mit unterschiedlichen Farben, die sich örtlich kreuzen, beispielsweise entgegengesetzt laufen. Ein Betrachtungswinkelbereich für das erste Bewegungsmotiv erstreckt sich beispielsweise von -20° bis +20°, ein Betrachtungswinkelbereich für das zweite, gegenläufige Bewegungsmotiv umgekehrt von +20° bis -20°. Bei versetzt laufenden Bewegungsmotiven läuft ein Motiv beispielsweise von -20° bis +10°, das andere Motiv von -10° bis +20°.
• Ein binärer Motivflip, bei dem die gewölbten und/ oder dreidimensional erscheinenden verschiedenfarbigen Bildmotive ineinander liegen und/ oder einander überschneiden. Beim Kippen findet insbesondere ein gleichzeitiger Farbtausch des inneren und des äußeren Motivs bzw. der überschneidenden Motivteile statt. Die Betrachtungswinkelbereiche können die z-Richtung einschließen oder nicht einschließen. Ebenso können die Betrachtungswinkel (der Bereiche) positiv und negativ, nur positiv oder nur negativ sein.

More specifically, the following variants have proven to be particularly attractive:

• A binary motif flip between curved and/or three-dimensional image motifs with a binary color change. A first viewing angle range extends, for example, from +5° to +20° in relation to a surface normal of the security element, and a second viewing angle range from -5° to -20°. The first and second motif can also be identical, resulting in a purely binary color change.
• Pump or running effects with different colors that intersect locally, for example running in opposite directions. A viewing angle range for the first movement motif extends, for example, from -20° to +20°, a viewing angle range for the second, opposite movement motif, conversely, from +20° to -20°. In the case of staggered movement motifs, for example, one motif runs from -20° to +10°, the other motif from -10° to +20°.
• A binary motif flip, in which the arched and/or three-dimensional, differently colored image motifs lie within and/or overlap one another. When tilting, a simultaneous color change of the inner and outer motif or the overlapping parts of the motif takes place. The viewing angle ranges may or may not include the z-direction. Likewise, the viewing angles (of the areas) can be positive and negative, only positive, or only negative.

In an advantageous variant of the invention, the reflective surface area contains exactly two relief structures, each of which is arranged at a specific height level.

The relief structures of the reflective surface area are advantageously each characterized by a maximum pitch, the distance between adjacent height steps in the z-direction being greater than the maximum pitch of the embossed structure region lying deeper in each case. Preferably, the distance is greater than 150%, more preferably 200%, of the maximum pitch. More preferably, the distance between adjacent height steps in the z-direction is between 150% and 750%, particularly preferably between 200% and 500%, more preferably between 200% and 400% of the maximum pitch of the lower-lying embossed structure area.

The relief structures are preferably micromirror arrangements, in particular micromirror arrangements with directed micromirrors. The micro-mirror array(s) is (are) achromatic micro-mirror array(s) which is (are) non-diffractive in particular. The directed mirrors of the micromirror arrangement are distinguished by a preferred direction of reflection, which can be set, for example, by means of an angle of inclination and/or an azimuth angle. Depending on their orientation for the viewing angle, the individual directional micromirrors of the micromirror array either reflect the light towards the viewer or not (bright or dark). It is only through the color coating that the micromirror then appears as a reflective color or not (light or dark color). Surfaces aligned parallel or perpendicular to the multicolored reflective surface area are not directed mirrors in the present sense. The directed micromirrors can be formed regularly or irregularly (e.g. the same shape or varying shape) and/or arranged (e.g. in a pattern or distributed quasi-randomly). Plane mirrors are particularly suitable as directed mirrors. Alternatively, directed concave mirrors and/or directed Fresnel-like (ie understructured) mirrors can be used.

gegeben, wobei die einzelnen Mikrospiegel je nach Neigungswinkel eine Ganghöhe zwischen 0 und G_max haben können. Der Abstand der Mikrospiegelanordnung zur darüber liegenden Mikrospiegelanordnung ist dann vorteilhaft größer als 5,8 µm und liegt insbesondere zwischen 8,7 µm (150% von G_max) und 23,2 µm (400% von G_max). In der Regel weisen die Mikrospiegel eine einheitliche Größe, insbesondere Kantenlänge, auf. In anderen bevorzugten Ausgestaltungen weisen die Mikrospiegel der Mikrospiegelanordnung eine maximale Ganghöhe jedoch unterschiedliche Kantenlängen auf. Wenn für Mikrospiegel mit höherem Winkel eine kleinere Kantenlänge gewählt wird, kann eine kleinere maximale Ganghöhe eingehalten werden. Vorzugsweise sind Mikrospiegel mit einem Neigungswinkel unter einem Grenzwinkel mit einer einheitlichen Größe (bzw. Kantenlänge) und Mikrospiegel mit einem Neigungswinkel über dem Grenzwinkel mit verringerter Größe (bzw. Kantenlänge) vorgesehen. Im oben berechneten Beispiel mit G_max= 5,8 µm in einer Mikrospiegelanordnung können auf diesem Weg Mikrospiegel bis zu einer maximalen Neigung von etwa 49 Grad vorliegen, wenn deren Kantenlänge nur 5µm statt 10 µm beträgt.If the relief structures are formed by micromirror arrangements, for example, then the pitch of the micromirrors depends on their lateral dimensions and their angles of inclination. Even with the same lateral dimensions, the angles of inclination of the micromirrors are typically different, so that the micromirrors have different pitches. However, the maximum pitch of its micromirrors is characteristic of the micromirror arrangement. The above maximum pitches ("pitch less than") are preferred. If the micromirrors have, for example, an edge length of 10 μm and a maximum angle of inclination of 30°, then the maximum pitch of the micromirror arrangement is through $${\mathrm{G}}_{\mathrm{Max}}=10\mathrm{\mu }\mathrm{m}*\tan \left(30°\right)=5.8\mathrm{\mu }\mathrm{m}.$$

given, whereby the individual micromirrors can have a pitch between 0 and G _max depending on the angle of inclination. The distance between the micromirror arrangement and the micromirror arrangement above it is then advantageously greater than 5.8 μm and is in particular between 8.7 μm (150% of G _max ) and 23.2 μm (400% of G _max ). As a rule, the micromirrors have a uniform size, in particular edge length. In other preferred configurations, the micromirrors of the micromirror arrangement have a maximum pitch but different edge lengths. If a smaller edge length is chosen for higher angle micromirrors, a smaller maximum pitch can be maintained. Preferably, micromirrors with a tilt angle below one Critical angle provided with a uniform size (or edge length) and micro-mirror with a tilt angle above the critical angle with reduced size (or edge length). In the example calculated above with G _max = 5.8 μm in a micro-mirror arrangement, micro-mirrors with a maximum inclination of about 49 degrees can be present in this way if their edge length is only 5 μm instead of 10 μm.

Even if the procedure was explained using micromirror arrangements, a maximum pitch of the relief structures can also be determined analogously for other embossed relief structures.

In advantageous configurations, the color coatings of the relief structures are formed by translucent colors. Metallizations, for example made of aluminum, silver or an alloy, for example made of copper and aluminum, are also possible, as are thin-film structures, in particular color-shifting thin-film structures, color-stable, color-filtering thin-film structures (different colors in remission and transmission) or silicon-aluminum thin-films. The color coatings can also be formed by translucent colors with a metallic mirror coating underneath, for example made of aluminum. The color coatings can represent a translucent image made up of several translucent colors, which is backed by a mirror coating, for example made of aluminum. Luminescent colors, in particular fluorescent colors with a metallic mirror coating, can also be used as color coatings. Finally, nanoparticle colors can also be considered as color coatings, such as gold-blue particles, various effect pigments, color-shifting pigments or super silver.

A color coating preferably follows the relief course of its relief structure. One surface (or both surfaces) of the color coating follows the relief structure. The second surface of the color coating(s) preferably also follows the relief structure. Alternatively, the second surface can be flat. In a further alternative—which is more difficult to produce—the second surface of the color coating comprises a color-imparting colored structure, such as a sub-wavelength, nano or binary structure. The color coatings are preferably applied directly to the relief structures, in particular the micromirror arrays.

Different color coatings can also be present next to each other or on top of each other in certain areas. The color coatings are preferably applied directly to the embossed structures, in particular the micromirror arrays, and follow the course of the relief of the embossed structures. However, in the case of multi-layer color coatings, for example a translucent color with background metallization, it is also possible for only part of the multiple layers, for example the background metallization, to be applied directly to the embossed structures. The remaining part of the layers, for example the glazing paint, can then be arranged over the relief structures, for example between the coated relief structure area and the adjacent, higher-lying relief structure area. The second surface of a reflective partial layer of the color coating(s) preferably also follows the relief structure. The second surface of a translucent partial color layer of the color coating(s) can also follow the relief structure, be flat or follow the other relief structure. The remaining part of the layers can also be combined with further layers, for example. For example, the embossing varnish can be colored for the adjacent, higher-lying relief structure area be and thus represent a continuous colored partial coating for the lower-lying relief structure area. Preferably, the lower surface of the (first) colored embossing varnish follows the lower relief structure and the upper surface of the colored embossing varnish forms the upper (first) relief structure.

The color impressions of the first and second color coatings are different, they differ in their shade. Both color coatings preferably produce a chromatic shade. Alternatively, one of the two color coatings can produce an achromatic hue, preferably silver, for the viewer, and the other a chromatic hue.

Outside the feature area, in particular in an overlapping area of the two relief structures or outside the overlapping area, other color coatings, in particular with a third and/or a fourth color impression, can be used. Other color combinations, in particular with a third (for example with the first or second) color impression or with a third and fourth color impression, can be present in further feature areas or outside of the overlapping area. Likewise, one of the (first, second, third or fourth) color coatings outside the feature area or outside the overlapping area can have a different hue.

In addition to the color coating of the higher-lying relief structure, the color coating of the lower-lying relief structure can only be present in certain areas. Color coatings that are present in certain areas can either be applied in certain areas and/or selectively removed again after full-surface application. A number of advantageous methods are described below, with which the above-mentioned color coatings can only be applied in certain areas can be provided. The person skilled in the art is aware that not every method is suitable for all types of color coatings. In particular, if several different color coatings are used in a security element, several different methods can also be used in the structuring.

Structured color coatings with metallic colors, thin-layer colors, structural colors or nanoparticles can be created, for example, by using a wash color. For this purpose, wash ink is printed in insetter printing for the respective embossing structure, then the entire surface is metallized and then washed. To avoid any tolerance that may exist when printing the wash color, the relief structure can be further adjusted. In some areas, the relief structure can comprise an adhesion-reducing (and/or an adhesion-increasing) fine structure, which in particular has a hydrophobic (or hydrophilic) effect. The adhesion-reducing fine structure in one area thus in particular prevents the wash color from adhering to the area. A first area with an adhesion-reducing fine structure can optionally adjoin a second area with an adhesion-increasing fine structure. The use of an optionally colored etching resist is particularly advantageous in combination with translucent colors. For this purpose, the embossing structure can first be completely coated, then the etch resist is printed, with the desired areas remaining unprinted, and finally the coating is etched. Laser treatment can be used to remove metallic paints, metallic coatings, and laser-sensitive, translucent paints with high resolution. A light-absorbing fine structure, such as for example moth-eye structures or quasi-random structures, can be provided in regions in the relief structure. The absorption of light is thereby increased, so that no more lasers must be used. Normal light sources such as UV lamps or LEDs can also be used for removal. Metallic flakes, nanoparticle ink or super silver (usually nanoscale aluminum particles) can be printed directly in register. Instead of the etching resist mentioned above, an optionally colored photoresist can first be applied over the entire surface and then exposed in certain areas. Depending on the resist used, the exposed or unexposed areas then dissolve in the etching bath, so that the underlying metal dissolves, while the metallic areas covered by the photoresist remain protected from the etch.

Color coatings can also be created by a metal transfer process. Areas that are to be demetallized are embossed using an embossing tool. The foil that has been pretreated in this way is then completely metalized and the metal on the embossed areas is selectively removed with another foil so that only metal remains in the depressions. A color transfer can also be generated in a similar way. Areas that are later to appear in color are embossed compared to the remaining areas. A colorant, such as flakes, nanoparticle color, super silver or a translucent color is applied to a roller and selectively transferred to the embossed areas of the foil. Conversely, in a color filling process, a desired color coating is created by embossing areas that are later to appear colored relative to the remaining areas. A colorant, for example flakes, nanoparticle color, super silver or a translucent color is printed over the entire surface and then removed with a hard chambered squeegee or wiped off with a cloth so that the color only remains in the depressions.

The security element described can also be equipped with colorless or colored negative markings. For this purpose, it can be provided in particular that the overlapping area additionally contains partial areas with a negative marking, in which the color coating of the higher relief structure and at least partially also the color coating of the lower relief structure is omitted.

The color coating of the lower-lying relief structure can be left out completely in the partial areas of the negative marking, so that the negative marking does not produce any of the color impressions of the two color coatings. In particular, the negative mark appears colorless and is particularly easy to recognize in transmitted light.

In another embodiment, the color coating of the lower-lying relief structure is multi-layered, with at least one of the multiple layers being omitted in the partial areas of the negative marking, so that a colored negative marking is produced. Advantageously, the color coating of the lower-lying relief structure contains an opaque partial layer, in particular a metallization, and a translucent color layer, with the opaque partial layer being left out in the negative identification partial areas, but not the translucent color layer, so that a negative identification with the color effect of the translucent color layer is left out arises.

The line widths of the overlapping gaps in a negative identifier are advantageously above 100 μm, preferably above 150 μm, particularly preferably above 300 μm, in order to ensure that the negative identifier can be easily recognized.

In the case of a negative mark, the gaps in the color coating of the lower-lying relief structure are advantageously formed with a somewhat larger area than the gaps in the color coating of the higher-lying relief structure in order to compensate for register fluctuations between the two relief structures.

In an advantageous embodiment, the relief structures are arranged on opposite sides of a transparent carrier film. Alternatively, relief structures are arranged one above the other on the same side of a carrier film. The relief structures can be arranged directly one above the other or be separated from one another by an adhesive layer, for example a laminating adhesive layer or a laminating film. The laminating film can also form the flat carrier of the security element. After the security element has been applied to a target data carrier, the carrier of the target data carrier can also represent the flat carrier of the security element.

The invention also includes a data carrier with a security element of the type described. The data carrier can in particular be a document of value, such as a banknote, in particular a paper banknote, a polymer banknote or a foil composite banknote, a share, a bond, a certificate, a voucher , a check, a premium ticket, but also an identification card, such as a credit card, a bank card, a cash card, an authorization card, an ID card or a passport personalization page.

• ein Träger bereitgestellt wird, dessen Flächenausdehnung eine x-y-Ebene und eine darauf senkrecht stehende z-Achse definiert,
• der Träger mit einem mehrfarbigen reflektiven Flächenbereich versehen wird, der mit zumindest zwei Reliefstrukturen ausgebildet wird, die in z-Richtung in unterschiedlichen Höhenstufen bezogen auf den flächigen Träger angeordnet werden,
• die Reliefstrukturen jeweils mit einer Farbbeschichtung versehen werden, die bei Betrachtung aus +z-Richtung einen unterschiedlichen Farbeindruck der beiden Reliefstrukturen erzeugen, und
• die beiden Reliefstrukturen überlappend ausgebildet werden und die Farbbeschichtung des höher liegenden Reliefstruktur im überlappenden Bereich in einem Merkmalsbereich als regelmäßiges oder unregelmäßiges Raster mit Rasterelementen und Rasterzwischenräumen ausgebildet wird, wobei die Abmessungen der Rasterelemente und/ oder Rasterzwischenräume zumindest in einer Richtung unterhalb von 140 µm liegen, so dass im Merkmalsbereich die Farbbeschichtung des tiefer liegenden Reliefstruktur durch die Rasterzwischenräume der Farbbeschichtung des höher liegenden Reliefstruktur in Erscheinung tritt.

Finally, the invention also includes a method for producing a security element of the type described above, in which

• a carrier is provided, the surface area of which defines an xy plane and a z-axis perpendicular thereto,
• the carrier is provided with a multicolored reflective surface area which is formed with at least two relief structures which are arranged in the z-direction at different height levels in relation to the planar carrier,
• the relief structures are each provided with a color coating which produces a different color impression of the two relief structures when viewed from the +z direction, and
• the two relief structures are formed in an overlapping manner and the color coating of the higher relief structure in the overlapping area is formed in a feature area as a regular or irregular grid with grid elements and grid spaces, the dimensions of the grid elements and/or grid spaces being less than 140 µm in at least one direction, so that in the feature area the color coating of the lower-lying relief structure appears through the raster interstices of the color coating of the higher-lying relief structure.

For the sake of completeness, it should be noted that the resulting color impression is determined by the color coating, so that the present relief structures could also be referred to as achromatic relief structures. Colored structures, such as diffraction gratings, sub-wavelength gratings or blazed gratings, which filter, diffract and/or reflect white light wavelength-selectively, are not relief structures in the present sense create your own color impression. In configurations, the carrier can be part of the security element. In other configurations, the security element is removed from the carrier, for example when the security element is transferred from the carrier to a target substrate.

Further exemplary embodiments and advantages of the invention are explained below with reference to the figures, which are not shown to scale and proportions in order to improve clarity.

Fig. 1

eine schematische Darstellung einer Banknote mit einem erfindungsgemäßen Sicherheitselement,

Fig. 2

schematisch einen Ausschnitt des Sicherheitselements der Fig. 1 im Querschnitt,

Fig. 3

in (a) bis (d) einige konkrete vorteilhafte Ausgestaltungen des Rasters der Farbbeschichtung der höher liegenden Mikrospiegelanordnung in Aufsicht,

Fig. 4 bis 7

einige visuell attraktive Effekte, die sich mit erfindungsgemäßen Sicherheitselementen verwirklichen lassen, wobei in (a) und (b) jeweils der Merkmalsbereich eines Sicherheitselements in zwei unterschiedlichen Kippstellungen gezeigt ist,

Fig. 8

in (a) bis (d) einige vorteilhafte Folienaufbauten erfindungsgemäßer Sicherheitselemente,

Fig. 9

ein erfindungsgemäßes Sicherheitselement mit einem zusätzlich Bereich mit einer Farbe-zu-Effekt-Passerung, und

Fig. 10

ein erfindungsgemäßes Sicherheitselement mit einem zusätzlich Bereich mit einer Negativkennzeichnung.

Show it:

1

a schematic representation of a bank note with a security element according to the invention,

2

schematically shows a section of the security element 1 in cross section,

3

in (a) to (d) some concrete advantageous configurations of the grid of the color coating of the higher-lying micromirror arrangement in plan view,

Figures 4 to 7

some visually attractive effects that can be achieved with security elements according to the invention, with the feature area of a security element being shown in two different tilted positions in (a) and (b),

8

in (a) to (d) some advantageous film structures of security elements according to the invention,

9

a security element according to the invention with an additional area with a color-to-effect registration, and

10

a security element according to the invention with an additional area with a negative marking.

The invention will now be explained using the example of security elements for banknotes. figure 1 shows a schematic representation of a banknote 10 with an optically variable security element 12 according to the invention in the form of an adhesively bonded transfer element. It goes without saying, however, that the invention is not limited to transfer elements and banknotes, but can be used with all types of security elements, for example labels on goods and packaging or to protect documents, ID cards, passports, credit cards, health cards and the like. In the case of banknotes and similar documents, in addition to transfer elements (such as patches with or without their own backing layer), security threads or security strips, for example, can also be considered.

This in 1 The security element 12 shown is itself very flat, but still gives the viewer a three-dimensional impression and also shows a binary change in color and effect when the banknote 10 is tilted Banknote 10 bulging motif 14-A, e.g. a bulged representation of the denomination "10" appearing with a first color, e.g. red. From a second viewing direction, the security element 12 shows a second motif that appears to bulge out of the plane of the bank note 10 14-B, for example, a domed representation of a coat of arms appearing with a second color, for example, blue.

When the bank note 10 is tilted 16 or when the viewing direction changes accordingly, the appearance of the security element 12 suddenly jumps from the first to the second appearance, or when it is tilted back from the second to the first appearance. The change in motif (number or coat of arms) and color (red or blue) takes place simultaneously and without an intermediate or transitional stage in which both motifs or colors would be visible at the same time or one motif would be visible in the color of the other motif were. The appearance therefore jumps seamlessly between two appearances 14-A, 14-B and is therefore referred to as a binary color and effect change.

The special structure of optically variable security elements according to the invention will now be discussed with reference to FIG 2 explained in more detail, which shows a section of the security element 12 schematically in cross section. The security element 12 contains a flat carrier 18, whose surface extent defines an xy plane and a z-axis perpendicular thereto.

A multicolored reflective surface area 20 is arranged on the carrier 18, which contains two embossed structure areas 24, 34, which are arranged in the z-direction at two specific, different height levels in relation to the planar carrier 20. In the exemplary embodiment, the embossed structure areas each represent micromirror embossings or micromirror arrangements 24, 34, which are each formed from a multiplicity of micromirrors inclined with respect to the xy plane. The local angles of inclination of the micromirrors are selected in such a way that the relief structure of the micromirror arrangements 24, 34 after the color coating is a desired one optical appearance created. The different levels of height are given by the different heights H ₁ , H ₂ of the base areas of the micromirror arrangements 24 , 34 above the carrier 18 .

Specifically, the angles of inclination of the micromirrors in the exemplary embodiment are selected such that the micromirror arrangement 24 generates the curved representation of the value number "10" in a viewing angle range of +5° to +20° (viewing position 40-A) related to the surface normal 42 and the micromirror arrangement 34 in a viewing angle range of -5° to -20° (viewing position 40-B), the convex representation of the coat of arms is generated.

In order to create a visual contrast with the desired color effect, the micromirror arrangements 24, 34 are each provided with a color coating 26, 36, which produce the different color impression of the micromirror arrangements when viewed from above from a viewing position 40-A or 40-B of the viewer 40 . In the exemplary embodiment, the micromirror arrangement 24 is coated with a red, glazing paint 26 , while the micromirror arrangement 34 is coated with a blue, glazing paint 36 .

The micromirror arrangements 24, 34 are each embossed in a transparent embossed lacquer layer 22, 32 and, after the application and, if necessary, structuring of the respective color coating 26, 36, are leveled with a transparent top lacquer layer 28 or 38, respectively. The top coat layers have essentially the same refractive index as the embossing coat layers 22, 32, so that the micromirrors do not appear visually in areas without a color coating due to the lack of a refractive index difference between the embossing coat layer and the top coat layer.

The security element 12 is designed for viewing from above (in reflection), so that the micromirror array 24 further away from the viewer 40 is referred to as the lower micromirror array and the micromirror array 34 closer to the viewer 40 is referred to as the higher micromirror array.

In the exemplary embodiment, the two micromirror arrangements 24, 34 are arranged one above the other in the entire surface area 20 of the security element 12. While the red color coating 26 of the lower micromirror arrangement 24 is continuous, the blue color coating 36 of the higher micromirror arrangement 34 is formed in a feature area of the security element in the form of a regular grid 50 of grid elements 52 and grid spaces 54 . Specifically, the raster elements 52 and raster spaces 54 form a chessboard pattern in the exemplary embodiment, in which each field, ie each raster element 52 and each raster space 54, has dimensions of 100 μm×100 μm. Since the micromirrors are generally significantly smaller, for example having an edge length of only 10 μm, the grid 50 of the color coating 36 falls, unlike in the simplified schematic representation of FIG 2 , generally do not match the array of micromirrors of micromirror array 34 .

From the viewing direction 40-A, the micromirrors of the micromirror arrangement 34 in the gaps between the grids 54 do not develop any optical effect due to the lack of a difference in the refractive index of the lacquer layers 32, 38, so that the viewer 40 there sees the red coated micromirrors of the micromirror array 24 looks. In the field of grid elements 52, the micromirrors of the micromirror arrangement 34 are basically perceptible, but their orientation is far removed from the glancing angle and they therefore appear inconspicuous from the viewing direction 40-A and practically do not contribute to the image impression. Overall, the observer from the viewing direction 40-A thus essentially sees the red appearance 14-A of the curved denomination “10” generated by the micromirror arrangement 24.

From the viewing direction 40-B, the viewer looks at the blue-coated micromirrors of the micromirror arrangement 34 in the area of the raster elements 52. In the area of the raster interspaces 54, the viewer can basically perceive the micromirrors of the lower-lying micromirror arrangement 24, but their alignment from the viewing direction 40- B far from the specular angle. The micromirror arrangement 24 therefore appears inconspicuous and practically does not contribute to the image impression. Overall, the observer from the viewing direction 40-B thus essentially sees the blue appearance 14-B of the curved coat of arms generated by the micromirror arrangement 34.

Since the grid elements 52 and the grid gaps 54 each have the same dimensions, the area coverage of the grid 50 in the exemplary embodiment is 50%, which also results in the same brightness of the two appearances 14-A, 14-B with the selected color coatings 26, 36. If colors or color coatings of different brightness are selected for the two micromirror arrangements, a surface coverage of the raster 50 that deviates from 50% can also be selected in order to compensate for the different color brightnesses and produce appearances 14-A, 14-B that are approximately the same brightness. Alternatively, through the Area coverage also targeted different bright appearances 14-A, 14-B are generated.

figure 3 shows some specific advantageous configurations of the grid of the color coating 36 of the higher-lying micromirror arrangement 34 in plan view. while showing 3(a) a grid 50 as in 2 is used, in which the grid elements 52 and the grid spaces 54 form a checkerboard pattern. The dimensions of the grid elements and grid spaces are advantageously between 20×20 μm ² and 140×140 μm ² , the area coverage is 50%. If a different area coverage is to be generated, part of the raster elements 52 can be omitted or part of the raster spaces 54 can be covered with raster elements. In this configuration, but also in the configurations described below, the area coverage of the grid with grid elements is preferably between 30% and 70%, in particular between 40% and 60%.

Figure 3(b) shows a grid 50 with alternately arranged strip-shaped grid elements 52 and grid spaces 54. The width of the grid elements and grid spaces is advantageously between 20 μm and 140 μm, the length is arbitrary and can be several millimeters or even a few centimeters. The area coverage can be easily adjusted via the relative width of the grid elements and grid spaces.

The grid elements and grid spaces can also have other polygonal shapes or irregular shapes. example shows 3(c) an embodiment in which the grid elements 52 and grid gaps 54 of the grid 50 are formed by triangles. At the grid 50 of 3(d) the grid elements 52 and grid spaces 54 are formed by irregular shapes. The grid elements and/or grid spaces can also form a coherent structure, such as in 3(d) for the grid spaces 54 are shown.

The Figures 4 to 7 illustrate some visually attractive effects that can be realized with security elements according to the invention. The figures in (a) and (b) each show the feature area of a security element in two different tilt positions, for example tilted down or up or tilted to the left or right.

In the security element 60 of the embodiment of 4 the angles of inclination of the micromirrors of the lower-lying, red-coated micromirror arrangement 24 are selected in such a way that they produce a red rolling bar effect in the feature area, i.e. a bright red bar 62 that, depending on the direction of tilting, appears along the feature area of the security element 60 appears to run up and down as indicated by the arrows in 4(a) and (b) implied. The angles of inclination of the micromirrors of the higher-lying, blue-coated micromirror arrangement 34 are selected in such a way that they simultaneously produce an opposing blue rolling bar effect in the feature area, i.e. a bright blue bar 64 which, when the security element is tilted, appears in the opposite direction to the red bar of the underlying micromirror arrays 24 runs. Due to the screening of the higher, blue color coating 36, both the blue bar 64 of the higher-lying micromirror arrangement 34 and the red bar 62 of the lower one are always, even in the overlapping position in which both bars 62, 64 appear to be at the same place Lying micro-mirror array 24 visible, so that the two bars 62, 64 seem to run through each other for the viewer. The difference in height of the two micromirror arrays 24, 34 is in the range of a few microns or tens of microns and is therefore visible to the viewer imperceptible. In almost all parts of the feature area, either the color coating of the higher-lying relief structure or the color coating of the lower-lying relief structure appears for the observer in this example, depending on the viewing angle. In the part of the feature area where the bars are superimposed, both color coatings are visible at the same time. The fact that a mixed color tone is created in this part is less noticeable due to the movement of the bars.

In variants that are not shown, the security element 60 can show other optical effects adjacent to or adjacent to the depicted feature area, for example a non-moving - possibly curved - blue border strip adjacent to the right, a non-moving - possibly curved - red border strip adjacent to the left and/or above and below (in top view) a non-moving - possibly curved - lilac edge stripe.

figure 5 shows a modification of the design of the 4 , in which the micromirror arrays 24, 34 again produce a red or blue rolling bar effect. In contrast to the design of 4 are the two colored bars 62, 64 in the security element figure 5 offset from each other and move together in the same direction when tilted, as indicated by the arrows in the figure. Alternatively, the bars 62, 64 can also move in the same direction at different speeds and amplitudes, so that one bar appears to be overtaken by the other bar during the tilting movement. Due to the grid of the color coating, both bars are always visible, even in the overlapping position in which both bars appear to be in the same place.

The security element 70 of 6 shows an attractive combination of color change with 3D and motion effect. The tilt angles of the micromirrors of the micromirror arrangements 24 are selected in such a way that they each produce two nested rings 72 or 74 with a three-dimensional appearance for the viewer, with the red rings 72 of the lower-lying micromirror arrangement 24 being visible in a viewing angle range of +5° to +20° ( 6(a) , corresponding to viewing position 40-A in 2 ), and the blue rings 74 of the upper micromirror array 34 are visible over a viewing angle range of -5° to -20° ( Fig.6(b) , corresponding to viewing position 40-B in 2 ). When the security element 70 is tilted, in addition to the three-dimensional appearance of the rings 72, 74, there is also a binary color change from red to blue and back.

figure 7 shows a modification of the design of the 6 , in which the micromirror arrangements 24, 34 again produce rings that appear three-dimensional, but here in such a way that in a viewing angle range of +5° to +20° the inner red ring 72-A of the lower-lying micromirror arrangement 24 and at the same time the outer blue ring 74- B of the higher-lying micromirror array 34 are visible ( Fig.7(a) ). Conversely, in a viewing angle range of -5° to -20°, the outer red ring 72-B of the lower micromirror array 24 and the inner blue ring 74-A of the upper micromirror array 34 are visible ( Fig.7(b) ). The security element 70 of 7 therefore shows red and blue rings lying one inside the other with a three-dimensional appearance, with the outer and inner ring binary changing color when the security element is tilted.

Some advantageous film structures of security elements according to the invention are in 8 shown. In the security element 80 of 8(a) is on the two opposite sides of a transparent PET carrier film 18 each have a transparent embossing lacquer layer 22, 32 with the desired micromirror embossing 24, 34, the color coating 26, 36 and the transparent top lacquer layer 28, 38 are arranged. The security element 80 is designed for viewing from the side of the color coating 36, so that the color coating 36 of the higher-lying micromirror array 34 is designed as a grid with grid elements 52 and grid spaces 54 through which the viewer looks at the lower-lying micromirror array 24 with the color coating 26 .

The security element 82 of Fig.8(b) already indicates it 2 described layer structure. Both micromirror embossings 24, 34 are arranged on the same side of the carrier film 18, which does not have to be transparent in this configuration. The first embossing lacquer layer 22 with the first, deep micromirror embossing 24, the first color coating 26, the first transparent cover layer 28, the second, transparent embossing lacquer layer 32 with the second, higher micromirror embossing 34, the second color coating 36 and the second transparent cover layer 38 is arranged. The security element 82 is designed for viewing from the side of the color coating 36, so that the color coating 36 of the upper micromirror array 34 is designed as a grid with grid elements 52 and grid spaces 54 through which the viewer looks at the lower micromirror array 24 with the color coating 26 .

Other variants of are not shown separately in the figures Figure 8b . A transparent film can also be arranged above the further layers 22, 26, 28 and 32, 36, 38. The transparent film can be the carrier film 18 of the security element, be another carrier film or serve as a protective film. The order of the further layers 22, 26, 28 and 32, 36, 38 can be unchanged. Alternatively, the first embossing lacquer layer 22 can lie above the first top layer 28 and/or the second embossing lacquer layer 32 can lie above the second top layer 38 . Below the transparent film 18 arranged at the top, for example, the further layers follow in the order 32, 36, 38, 22, 26, 28.

Regardless of the position of the carrier film 18 are starting from Figure 8b the following variants are possible. The color coating 26 and the top layer 28 and/or the color coating 36 and the top layer 38 can be formed by a color coating 26 or 36 with—in particular a flat—upper surface. The color coating 26 and/or 36 comprises a reflective sub-layer (such as metallization) which follows its relief structure with both surfaces, and a translucent color sub-layer whose lower surface follows the relief structure, while the upper surface of the translucent color sub-layer does not follow the relief structure follows, is preferably flat. In a further variant, an upper, colored, glazed partial layer forms the lower color coating 26 in Figure 8b the lower cover layer 28 and at the same time the upper embossing lacquer layer 32. The color coating 26 preferably in turn comprises a reflective partial layer (such as metallization), which follows its relief structure with both surfaces. A transparently colored partial layer, preferably an embossing lacquer layer, follows the color coating 26 with its lower surface of the lower relief structure 24 and with its upper surface of the upper relief structure 34. In an even more extensive variant, the lower color coating comprises at least (or exactly) three partial layers, one reflective Sub-layer, a leveling sub-layer and a sub-layer with translucent color, preferably colored embossing varnish. The reflective partial layer follows with one (or both) surface(s) of the second, lower relief structure 24 and the colored glazing partial layer follows with its upper side the first, upper relief structure 34.

In other configurations, two foils 18-A, 18-B can also be used in the production of the security element, which are each separately provided with one of the micromirror structures 22-28 or 32-38 and then suitably laminated together.

When the security element 84 of Fig.8(c) the two carrier films 18-A, 18-B are laminated together in such a way that the micromirror structures 22-28 and 32-38 are on the inside. The lamination 86 can include a lamination film or also be formed only by a lamination adhesive. With this configuration, one or both of the carrier foils 18-A, 18-B can be removed after lamination in order to make the security element 84 as thin as possible. In particular when using a laminating film, both carrier films 18-A, 18-B can even be removed, since the stability of the security element 84 is ensured by the laminating film, which then acts as a flat carrier of the security element. The security element 84 is also designed for viewing from the side of the color coating 36, so that the color coating 36 of the higher-lying micromirror arrangement 34 is designed as a grid with grid elements 52 and grid spaces 54, through which the viewer can see the lower-lying micromirror arrangement 24 with the colored coating 26 looks.

When security element 88 of Figure 8(d) the carrier foils 18-A, 18-B are laminated together in such a way that one micromirror structure 22-28 is on the inside and the other micromirror structure 32-38 is on the outside. The lamination 86 can comprise a lamination film or can only be formed by a lamination adhesive. The carrier film 18-A on the outside can be removed after lamination be in order to form the security element 88 as thin as possible. Here, too, the color coating 36 of the higher-lying micromirror arrangement 34 is designed as a grid with grid elements 52 and grid gaps 54 in order to enable the viewer to look at the lower-lying micromirror arrangement 24 with the color coating 26 .

Finally, a further variant, not shown in the figures, consists in laminating the carrier foils together in such a way that both micromirror structures 22-28 or 32-38, 52, 54 are on the outside.

As already explained in more detail above, the color coatings 26, 36 can be formed not only by translucent colors, but also, for example, by metallizations, by thin-film structures, by translucent colors backed with a metallization, by luminescent colors with metallic mirroring, by structural colors or by nanoparticle colors.

As also already explained, the carrier film 18 is an optional element. It can therefore be omitted in any of the variants shown, mentioned or below. For example, the carrier film can be 18 in Fig.8(b) , the carrier foil(s) 18-A/B in Fig.8(c) or the carrier foil 18-A in Figure 8(d) be removed before (or after) the security element is applied to a target substrate. A release layer, not shown, which lies between the carrier film and the further layers, is provided in such configurations.

The security elements according to the invention can also have sub-areas in addition to the feature area described with a screened color coating with other effects, such as color-to-effect registration or negative marking.

In the case of the security element 90 shown as an example for this purpose 9 For the sake of simplicity, only the micromirror structures 22-28 and 32-38 are shown without carrier foils or further layers of the layer structure. The security element 90 contains a feature area 92 in which the micromirror arrays 24, 34 and color coatings 26, 36 are formed as described above and in particular the color coating 36 is formed in the form of a grid with small grid elements 52 and grid spaces 54.

In addition to the feature area 92, the security element 90 has an identification area 94 with a color-to-effect register. There, in a first partial area 94-A, a motif that appears to bulge out of the plane of the security element 90 or a movement effect with a first color, for example blue, is visible. Within the blue motif, a movement effect with a second color is visible in a second partial area 94-B, for example a red rolling bar effect. As a special feature, the areas of different colors (red or blue) and different effects (bulging motif or running bar) are precisely matched to each other.

For this purpose, the color coating 36 of the higher-lying micromirror arrangement 34 has a large-area cutout 96 with a dimension of more than 140 μm, in particular more than 300 μm, in the partial area 94-B. In the area of the recess 96, the micromirrors do not develop any optical effect due to the lack of a difference in refractive index between the lacquer layers 32, 38, so that the viewer can see through these lacquer layers looks at the underlying micro-mirror array 24 with its red paint coating 26. On the other hand, outside of the cutout 96 the visual impression of the identification area 94 is determined by the higher-lying micromirror arrangement 34 with its blue color coating 36 .

An observer therefore perceives the blue motif generated by the micromirror arrangement 34 outside the cutout 96, i.e. in the partial area 94-A, while the red rolling bar effect of the micromirror arrangement 24 appears within the cutout 96, in the partial area 94-B kicks. The height difference between the two micromirror arrays 24, 34 is in the range of a few micrometers or a few tens of micrometers and is therefore imperceptible to the viewer. The two differently colored motifs and the different effects of the partial areas 94-A, 94-B therefore appear to the observer to be arranged next to one another in exact register.

In the embodiment of 10 In addition to a feature area 92 of the type described above, the security element 100 also has partial areas 102 in which the color coatings 26, 36 of both micromirror arrangements 24, 34 are recessed (recesses 96 and 104, respectively), so that the security element 100 does not have any of the color impressions in these areas of the two color coatings shows.

The shape of the partial areas 102 forms a negative identifier, in particular negative writing, which can be seen particularly well in transmitted light given an at least translucent configuration of the further layers of the security element 100 . In the partial areas 102, the recesses 104 of the color coating 26 of the lower-lying micromirror arrangement 24 are formed with a somewhat larger area than the associated recesses 96 in the color coating 36 in order to absorb register fluctuations between the two embossed structures 24, 34. The line widths of the recesses 96, 104 lying one above the other are greater than 100 μm, in particular greater than 300 μm, in order to ensure that the negative markings can be easily recognized.

Colored negative marks can also be provided. For this purpose, for example, the color coating 26 of the lower-lying micromirror arrangement 24 can be formed in multiple layers, for example by a glazing color backed with a metallization. In addition to the color coating 36 of the higher-lying micromirror arrangement 34, the metallization of the color coating 26 of the lower-lying micromirror arrangement 24 is then left out in the negative identification partial areas, but the translucent color is preserved. The negative marking then appears colored and translucent due to the lack of metallization there.

Reference List

10

bank note

12

security element

14-A

bulging motif "10"

14-B

bulging motif "coat of arms"

16

tilt direction

18

carrier

18-A, 18-B

carrier films

20

reflective surface area

22, 32

embossing layer

24, 34

micromirror array

26.36

color coating

28.38

topcoat layer

40

viewer

40-A, 40-B

viewing positions

50

grid

52

grid elements

54

grid gaps

60

security element

62, 64

bar

70

security element

72, 72-A, 72-B

red rings

74, 74-A, 74-B

blue rings

80, 82, 84

security element

86

lamination

88

security element

90

security element

92

feature area

94

license plate area

94-A, 94-B

sub-areas

96

large recess

100

security element

102

Sections with negative indicators

104

recesses

Claims (16)

1. Optically variable security element (12), the planar extent of which defines a z-direction perpendicular thereto, having a polychromatic, reflective surface region (20), wherein

   - the polychromatic, reflective surface region (20) contains two relief structures (24, 34) arranged at different levels in the z-direction,

   - the relief structures (24, 34) are each provided with a colour coating (26, 36) which generates a different colour impression,

   - the two relief structures (24, 34) overlap in a feature region,

   - the colour coating (36) of the relief structure (34) higher up is formed in the feature region as a regular or irregular raster (50) with raster elements (52) and raster interspaces (54), and

   - the dimensions of the raster elements (52) and/or raster interspaces (54) are below 140 µm in at least one direction such that, to an observer at at least one observation angle, the colour coating (26) of the relief structure (24) further down becomes visible in the feature region through the raster interspaces (54) of the colour coating (36) of the relief structure (34) higher up.
2. Security element according to Claim 1, characterized in that the raster elements and raster interspaces of the raster have the same shape and preferably also the same size.
3. Security element according to Claim 1 or 2, characterized in that the surface coverage of the raster by the raster elements is between 30% and 70%, preferably between 40% and 60%, in particular approximately 50%; wherein in particular the surface coverage of the raster and the brightness of the colour coatings are matched to one another in order, upon observation, to generate substantially the same brightness of the colour coating of the relief structure higher up and the colour coating of the relief structure further down, which is becoming visible through the raster interspaces.
4. Security element according to at least one of Claims 1 to 3, characterized in that the dimensions of the raster elements and/or the raster interspaces in one or both lateral directions are between 20 µm and 140 µm, preferably between 40 µm and 120 µm, in particular between 60 µm and 100 µm.
5. Security element according to at least one of Claims 1 to 4, characterized in that, in at least one part of the feature region, either the colour coating (36) of the relief structure (24) higher up or the colour coating (26) of the relief structure (34) further down becomes visible to the observer depending on the observation angle, wherein, in a different part of the feature region, both colour coatings preferably are visible to the observer at the same time at at least one observation angle.
6. Security element according to at least one of Claims 1 to 5, characterized in that the two relief structures, depending on the observation angle, provide the colour change for an unchanging motif or provide the colour change together with a motif change, with the motifs of the two relief structures differing in particular in view of the shape, movement and/or three-dimensional property of the motif.
7. Security element according to at least one of Claims 1 to 6, characterized in that the relief structure higher up generates a first motif with a first colour impression visible from a first observation angle range and the relief structure further down generates a second motif with a second, different colour impression visible from a second observation angle range, with the first and the second observation angle ranges not intersecting.
8. Security element according to at least one of Claims 1 to 7, characterized in that the relief structure higher up generates a first movement motif with a first colour impression and the relief structure further down generates a second movement motif with a second, different colour impression, wherein, when the security element is tilted, the first and the second movement motif

   - move offset to one another or move counter to one another and, in the process, cross in an intersection position in which the two movement motifs are visible, and/or

   - successively move through the same part of the feature region.
9. Security element according to at least one of Claims 1 to 8, characterized in that the reflective surface region contains precisely two relief structures, which are each arranged on a specific level.
10. Security element according to at least one of Claims 1 to 9, characterized in that the relief structures are each characterized by a maximum pitch and the spacing of adjacent levels in the z-direction is greater than the maximum pitch of the relief structure further down, preferably between 150% and 750%, particularly preferably between 200% and 500%, of the maximum pitch of the relief structure further down.
11. Security element according to at least one of Claims 1 to 10, characterized in that the colour coatings are formed by transparent inks, by metallizations, thin-film structures, by transparent inks deposited with a metallization, by luminescent inks with a metallic reflection, by textured inks and/or by nanoparticle inks.
12. Security element according to at least one of Claims 1 to 11, characterized in that at least one partial region with a negative characteristic, in which the colour coating of the relief structure higher up and, at least in part, also the colour coating of the relief structure further down is cut out, is additionally provided in the overlapping region; wherein in particular

    - the colour coating of the relief structure further down is completely cut out in the negative characteristic partial region such that the negative characteristic generates neither of the colour impressions of the two colour coatings, or

    - the colour coating of the relief structure further down has a multi-layer form, and at least one of the plurality of layers is cut out in the negative characteristic partial region such that a coloured negative characteristic arises, preferably that the colour coating of the relief structure further down has an opaque partial layer, in particular a metallization, and a translucent colour layer, and the opaque partial layer but not the translucent colour layer is cut out in the negative characteristic partial regions so that a negative characteristic with the colour impression of the translucent colour layer arises.
13. Security element according to at least one of Claims 1 to 12, characterized in that

    the relief structures are formed by micromirror arrangements with directed micromirrors, in particular with planar mirrors, concave mirrors and/or Fresnel-type mirrors; and/or

    each raster element comprises precisely one directed micromirror or a plurality of directed nanomirrors or micromirrors.
14. Data carrier having an optically variable security element according to at least one of Claims 1 to 13.
15. Method for producing an optically variable security element (12) having a polychromatic, reflective surface region (20), in particular according to at least one of Claims 1 to 13, wherein

    - a carrier (18) is provided, the planar extent of which defines an xy-plane and a z-axis perpendicular thereto,

    - the carrier (18) is provided with a polychromatic, reflective surface region (20) which is formed with at least two relief structures arranged at different levels in the z-direction in relation to the planar carrier,

    - the relief structures are each provided with a colour coating which generates a different colour impression,

    - the two relief structures (24, 34) are embodied to overlap in a feature region,

    - wherein the colour coating (36) of the relief structure (34) higher up is formed in the feature region as a regular or irregular raster (50) with raster elements (52) and raster interspaces (54), and

    - wherein the dimensions of the raster elements (52) and/or raster interspaces (54) are below 140 µm in at least one direction such that, to an observer at at least one observation angle, the colour coating (26) of the relief structure (24) further down becomes visible in the feature region through the raster interspaces (54) of the colour coating (36) of the relief structure (34) higher up.
16. Method according to Claim 15, characterized in that the optically variable security element (12) is separated from the carrier (18).

Images