OPTICALLY VARIABLE SURFACES PATTERN

Description

[0001] The invention relates to an optically variable surface pattern and a security document with such an optically variable surface pattern.

[0002] Objects to be protected are often equipped with an optically variable surface pattern that allows verification of the object's authenticity and also serves as protection against unauthorized reproduction.

[0003] Diffractive relief structures (holograms) and ray-optically effective relief structures (micromirrors or prisms) are known.

[0004] Diffractive relief structures produce colors through diffraction, whereby usually the entire color spectrum is traversed when tilting, or a white color impression is created through color mixing, for example in matte structures.

[0005] Optically effective relief structures inherently produce colorless images. By applying an additional color coating (for example, a color-shift coating), colors or color changes can be generated. Such coatings typically produce only one color or a color change defined by the coating under a specific viewing angle or specular reflection angle of the micromirrors.

[0006] From German patent application DE 10 2008 046 128 A1, an optically variable security element with an achromatic, matte-glossy matte area is known, which contains a reflective matte structure composed of a multitude of microelements. To manufacture the security element, the surface profile of the matte structure is embossed into a lacquer layer. The embossed lacquer layer can be coated with a reflective layer. Alternatively, the lacquer layer can be applied to a reflective layer and embossed after application.

[0007] The German patent application DE 10 2010 049 600 A1 deals with a security element comprising a substrate that contains an optically variable surface pattern in a surface area, which displays different appearances depending on the lighting and / or viewing direction. The surface pattern consists of an at least locally periodic arrangement of essentially ray-optical reflective elements, which are aperiodically offset from one another in their height above the surface area and can, for example, be formed by a relief structure provided with a semi-transparent metallic coating.

[0008] In publication US 2005 / 168 723 A1, an optically variable element with sub-surfaces having achromatic surface structures and different scattering, diffraction, and reflection characteristics is described, which are combined with a thin-film structure, whereby, when rotating or tilting, the viewer does not perceive a continuous color transition, but rather a defined, almost discrete color change.

[0009] The article "Optically variable micro-mirror array fabricated by graytone lithography," PW Leech, RA Lee, Microelectronic engineering 83 (2006), pages 351-356, deals with the fabrication of micromirror arrays using graytone lithography. Publication WO 2008 / 098753 A1 describes a high-refractive-index embossing varnish for the fabrication of micro-optical arrays, while Publication WO 2004 / 003668 A1 deals with the fabrication of holographic devices comprising a transparent high-refractive-index coating selectively applied to a transparent substrate containing a holographic image. Publication WO 2004 / 063977 A2 describes metal-containing transaction cards.

[0010] Based on this, the object of the invention is to provide an optically variable surface pattern with which various optical effects can be achieved.

[0011] According to the invention, the problem is solved by an optically variable surface pattern with the features of claim 1.

[0012] An optically variable surface pattern is provided for use as a security element for application to an object to be protected, comprising a reflective layer and a micromirror arrangement formed on the reflective layer, which has a plurality of semi-transparent micromirrors, wherein light incident on the micromirror arrangement is partly reflected in a first direction by reflection at the semi-transparent micromirrors and partly reflected in a second direction different from the first direction by passing through the semi-transparent micromirrors, striking the reflective layer, being reflected there and then passing through the semi-transparent micromirrors again, wherein the micromirrors are configured such that there is an essentially ray-optically effective relief structure which causes the reflection of the incident light in the first direction.and wherein the reflective layer and the micromirror arrangement are configured such that the light reflected in the first and second directions has different colors, wherein a transparent or semi-transparent layer is formed on the reflective layer, wherein, to form the micromirrors, the side of the transparent or semi-transparent layer facing away from the reflective layer is structured in a predetermined area, and wherein the transparent or semi-transparent layer is formed by an embossed lacquer layer. The optically variable surface pattern is configured such that, when the surface pattern is tilted, a first motion effect is achieved with the light rays reflected in the first direction and a second motion effect is achieved with the light rays reflected in the second direction.

[0013] Thus, the optically variable surface pattern according to the invention provides two reflected light rays, which are reflected in different directions, with which color effects and motion effects can be achieved.

[0014] In particular, a partially reflective coating can be formed in the predetermined area. The partially reflective coating can also be referred to as a reflection-enhancing coating.

[0015] The structuring and / or the partially reflective coating can be designed in such a way that a (essentially) ray-optically effective relief structure (and not a diffraction structure) is present, which causes the reflection of the incident light in the first direction.

[0016] A reflection-enhancing coating within the meaning of the present invention is, in particular, a coating that increases the reflectance, for example, from only about 20% to about 50%, such as semi-transparent layers. The reflection-enhancing coating can be a metallic coating, which is, for example, vapor-deposited. Aluminum, gold, silver, copper, palladium, chromium, nickel, and / or tungsten, as well as their alloys, can be used as coating materials. Alternatively, the reflection-enhancing coating can be formed by coating with a material having a high refractive index. The partially reflective coating and / or the reflective layer can be in the form of patterns, symbols, or codes and / or have recesses in the form of patterns, symbols, or codes.

[0017] The partially reflective coating can be a color-shifting layer, designed, for example, as a thin-film system or thin-film interference coating. This can be achieved, for example, by a high-refractive index layer of suitable thickness (the thickness is preferably adjusted so that the desired color is produced by interference of the light rays reflected at the upper and lower interfaces), a layer sequence of metal layer-dielectric layer-metal layer, or a layer sequence of at least three dielectric layers, where the refractive index of the middle layer is lower than the refractive index of the other two layers. The color-shifting layer can also be designed as an interference filter, a thin semi-transparent metal layer with selective transmission through plasma resonance effects, nanoparticles, etc. In particular, the color-shifting layer can also be realized as a liquid crystal layer, a diffractive relief structure, or a subwavelength grating.

[0018] The micromirrors, or rather the partially reflective surfaces of the micromirrors that cause the reflection of the incident light in the first direction, are preferably flat. The flatness of the partially reflective surfaces is not to be understood in a mathematically exact sense, since perfectly flat surfaces are generally never achievable in practice due to manufacturing limitations. Therefore, the flatness is preferably understood to mean that the surface is as flat as is technically possible. Alternatively, it is possible to make the partially reflective surfaces of the micromirrors curved (e.g., concave, convex, or corrugated). However, the curvature of the partially reflective surfaces of the micromirrors is preferably slight.

[0019] The semi-transparent layer can be designed, for example, as a colored layer or a colored layer. This allows the color of the light reflected in the second direction to be influenced or adjusted.

[0020] The transparent or semi-transparent layer can be a lacquer layer and, in particular, an embossed lacquer layer.

[0021] Furthermore, the structuring of the transparent or semi-transparent layer can be formed by embossing.

[0022] Furthermore, a semi-transparent color layer can be placed between the reflective layer and the transparent or semi-transparent layer. The color of the light reflected in the second direction can be influenced or adjusted using this semi-transparent color layer.

[0023] The transparent or semi-transparent layer and / or the semi-reflective coating can have a refractive index of at least 1.6 and preferably at least 1.8 in at least part of the visible spectrum.

[0024] Furthermore, the micromirrors can be embedded in a medium that, at least in part of the visible spectrum, has a refractive index that differs from the refractive index of the transparent or semi-transparent layer and / or the semi-reflective coating by at least 0.1, preferably by at least 0.2, and particularly preferably by at least 0.4. This embedding layer can be part of the optically variable surface pattern. However, it is also possible that it is the adjacent medium (e.g., air).

[0025] In the optically variable surface pattern, the reflective layer and the micromirror arrangement can be designed in such a way that the light reflected in the first and second directions has different colors.

[0026] Furthermore, the semi-transparent micromirrors can form a sawtooth-shaped profile. The arrangement of the micromirrors can be regular or irregular.

[0027] In particular, the side of the reflective layer facing the semi-transparent micromirrors and / or the side of the reflective layer facing away from the micromirrors can be flat.

[0028] In the optically variable surface pattern according to the invention, several of the micromirrors can be arranged next to each other in one arrangement direction and their dimension in the arrangement direction can be in the range of 2 µm to 3 mm, preferably from 3 µm to 100 µm and particularly preferably from 5 µm to 30 µm.

[0029] The optically variable surface pattern can be designed such that, when light is incident parallel to the macroscopic surface normal of the surface pattern, the first and second directions of the reflected light lie on opposite sides of the macroscopic surface normal. However, it is also possible for the first and second directions of the reflected light to lie on the same side of the macroscopic surface normal.

[0030] The partially reflective coating can have one or more (especially high-refractive-index) dielectric layers, a semi-transparent metallic layer, a layer of semiconducting material and / or a liquid crystalline layer.

[0031] Furthermore, the color generation at the reflective layer and / or at the surface of the micromirrors can be realized by subwavelength structures, in particular subwavelength gratings.

[0032] The reflective layer can comprise one or more metallic layers, a thin-film color-shift layer (especially with the structure absorber / dielectric / reflector or absorber / dielectric / reflector / dielectric / absorber), one or more (especially high-refractive-index) dielectric layers and / or a liquid-crystalline layer.

[0033] For example, ZnS, SiO2, TiO2, MgF2 can be used as the dielectric material for the partially reflective coating and the reflective layer.

[0034] The optically variable surface pattern according to the invention can be designed such that a wide variety of motion effects, e.g., when the surface pattern is tilted, are achieved with the light rays reflected in the first direction (or the light rays reflected in the second direction). For example, the "rolling bar" effect described in US 7,517,578 B2 can be achieved. According to the invention, the light rays reflected in the second direction (or in the first direction) also produce a corresponding motion effect, which can have the same or an opposite direction of movement and the same or different speeds of movement. Other motion effects can also be achieved when the optically variable surface pattern is tilted, such as so-called flip, running, or pumping effects. Advantageously, the movement is either parallel or counter-clockwise.

[0035] Furthermore, the optically variable surface pattern according to the invention (including its further developments) can be used as a security element, in particular as a security element for security papers, valuable documents or the like.

[0036] The security element can be designed in particular as a security thread, tear strip, security tape, security strip, patch, foil element, or label for application to security paper, valuables document, or the like. In particular, the security element can span transparent areas or cutouts. Furthermore, in the case of polymer or hybrid banknotes, the security element can be embedded under a foil.

[0037] The term "security paper" here refers specifically to the non-circulating precursor to a security document, which, in addition to the security element according to the invention, may also have other authentication features (such as luminescent substances incorporated into the volume). Security documents, in this context, refer on the one hand to documents produced from security paper. On the other hand, security documents can also be other documents and objects that can be provided with the security element according to the invention so that the security documents have non-copyable authentication features, thereby enabling authentication and simultaneously preventing unauthorized copying.

[0038] Furthermore, a valuation document with an optically variable surface pattern according to the invention (including its further developments) is provided.

[0039] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations given, but also in other combinations or on their own, without leaving the scope of the present invention.

[0040] The invention is explained in more detail below by way of example with reference to the accompanying figures, which also reveal essential features of the invention. For the sake of clarity, some of the figures are not drawn to scale or with true proportions. They show: Figure 1 shows a top view of a banknote with an optically variable surface element 10 according to the invention; Figure 2 shows an enlarged sectional view of two micromirrors of the optically variable surface element. Figur 1 Figure 3 shows a top view of a further embodiment of a rectangular surface area 13 of the optically variable element 10 according to the invention; Figure 4 shows an enlarged sectional view of two micromirrors 14 each from the two areas 21 and 22 according to the invention. Figur 3 Figures 5A-5C illustrate the "rolling bar" effect; Figure 6 shows an enlarged sectional view of two micromirrors 14 to illustrate the effect associated with Figuren 5A-5C described "rolling bar" effect; Figure 7 shows an enlarged sectional view of two micromirrors 14 of a further embodiment of the optically variable surface pattern according to the invention, and Figure 8 shows an enlarged sectional view of two micromirrors 14 of a further embodiment of the optically variable surface pattern 10 according to the invention.

[0041] At the in Fig. 1 In the embodiment shown, the optically variable surface pattern 10 according to the invention is integrated as a security element in a banknote 11 in such a way that it is in the Fig. 1 The front of the banknote is visible. Alternatively, the optically variable element 10 according to the invention can, for example, be in the form of a window thread 12.

[0042] In the embodiment described here, the optically variable element 10 has a rectangular surface area 13 with a plurality of micromirrors 14 formed on a reflective layer 15, as shown in particular in the enlarged cross-sectional view of two micromirrors 14 in Fig. 2 can be seen from this.

[0043] The micromirrors 14 are formed by an embossed lacquer layer 16, the side of which facing away from the reflective layer 15 is structured (here with a sawtooth profile), and a coating 17 which is provided on the structured side of the embossed lacquer layer 16. As shown in the illustration of the Fig. 2 As can be seen, the micromirrors 14 are inclined relative to the reflective layer 15 (angle α).

[0044] The coating 17 can be provided, but it is not mandatory. In particular, the coating 17 is designed as a partially reflective coating that specularly reflects part of an incident light ray L1, thus generating a first reflected light ray L2, and transmits another part of the incident light ray L1.

[0045] The transmitted portion passes through the embossing lacquer layer 16 (light beam L4), strikes the reflective layer 15 and is reflected by it (light beam L5), passes again through the embossing lacquer layer 16 and the coating 17, and exits as a second reflected light beam L3. The refraction occurring at the interfaces between the different media is in Fig. 2 The diagram is shown only schematically. Refraction occurs at the interface between the environment and the coating 17, as well as at the interface between the coating 17 and the embossing lacquer layer 16. Furthermore, multiple reflections, which can occur due to a second reflection of the light beam L5 to the reflective layer 15, are not considered.

[0046] As shown in the illustration Fig. 2 With the optically variable surface pattern 10 according to the invention, an incident light ray L1 is specularly reflected at the coating 17 or at the micromirror 14 in a first direction (first reflected light ray L2) and, by refraction at the interface between the environment and the coating 17 on the one hand and the interface between the coating 17 and the embossing lacquer layer 16 on the other hand and reflection at the reflective layer 15, in a second direction (second reflected light ray L3), wherein the two directions differ.

[0047] The brightness and color of the first reflected light ray L2 can be determined by the optical properties of the coating 17. The brightness and color of the second reflected light ray L3 can be determined, for example, by the optical properties of the reflective layer 15. Furthermore, it is possible to color the embossing lacquer layer 16, which also influences the color and brightness of the second reflected light ray L2.

[0048] It is therefore possible to adjust the color of the two reflected light rays L2 and L3 differently, so that an observer viewing the optically variable surface pattern 10 from a certain angle can perceive the color of the first reflected light ray L2, and from a second angle can perceive the color of the second reflected light ray L3. This creates a color-flip effect for the observer.

[0049] The different colors can become visible, for example, at very close viewing angles when the micromirrors 14 have a relatively small slope. This allows for very discrete, i.e., fast and distinct, color changes, which differ significantly from the continuous and rather slow color changes of, for example, a thin-film color-shift coating with absorber / dielectric / reflector.

[0050] The coating 17 can also be referred to as a reflection-enhancing coating, since it increases the reflectance of the micromirrors 14 compared to the case without coating 17.

[0051] The side of the reflective layer 15 facing the micromirrors 14 is preferably planar. Furthermore, the reflective layer 15 can be, for example, a metallic coating (e.g., Ag, Al, Cu, ...) or a color-shifting coating, in particular a thin-film system. The thin-film system can, for example, have an absorber / dielectric / reflector configuration.

[0052] The structuring of the side of the embossing lacquer layer 16 facing away from the reflective layer 5 is preferably produced by an embossing process. According to the invention, the structured embossing lacquer layer 16 (together with the optionally provided coating 17) thus serves simultaneously as a mirror (for the first reflected light beam L2) and as a prism (for the second reflected light beam L3).

[0053] The material of the embossing lacquer layer 16 and / or the coating 17 is selected such that its refractive index differs from that of the medium 18 (e.g., air) adjacent to the embossing lacquer layer 16 or the coating 17. In particular, the refractive index of the embossing lacquer layer 16 or the coating 17 is greater than that of the medium 18. The medium 18 could, for example, also be a protective lacquer layer (not shown).

[0054] In particular, the refractive indices of the embossing varnish layer 16 or the coating 17 and of the medium 18 can be chosen such that, with perpendicular incident light L1 (relative to the reflection layer 15), the two reflected light rays L2 and L3 are directed onto the same side of the macroscopic normal N of the optically variable surface pattern 10 ( Fig. 2 The light is reflected, but at different angles. This allows, for example, the creation of two-colored running effects that move in the same direction, but at different speeds. This can be used, for instance, to create a "rolling bar" effect, where two differently colored bars move in the same direction at different speeds.

[0055] In the optically variable surface pattern 10 according to the invention, the micromirrors 14 thus form a micromirror array or a micromirror arrangement 19, which performs the specular reflection of the first reflected light ray L2 and enables the reflection of the transmitted part of the incident light ray L1 at the reflection layer 15, so that the second reflected light ray L3 is generated.

[0056] The optically variable surface pattern 10 can, for example, have a first and a second area 21, 22, as shown in a schematic top view in Fig. 3 As indicated, the micromirrors 14 of the micromirror array 19 exhibit inclinations (angles α) that differ. In particular, the inclinations can be chosen such that the direction of the first reflected light ray L2 21 from the first region 21 coincides with the direction of the second reflected light ray L3 22 from the second region 22, although the colors of these two light rays differ. A corresponding sectional view of the micromirrors 14 from regions 21 and 22 is shown in Fig. 4 shown. Thus, both colors are visible to the viewer from the same viewing angle. These colors can therefore be presented to the viewer in extremely high resolution and perfectly registered, positioned side by side. The second reflected light ray L3 21 from the first area 21 and the first reflected light ray L2 22 from the second area point in different directions.

[0057] In a further embodiment, the so-called "rolling bar" effect can be generated using the optically variable surface pattern according to the invention. For this purpose, for example, the reflective layer 15 can be designed as a color-shift coating and the coating 17 as a layer with a high refractive index, so that, with appropriately selected layer thicknesses, the first reflected light ray L2 appears green and the second reflected light ray L3 appears magenta. In the illustrations in Fig. 5A-5C The magenta bar B1 is horizontally hatched and the green bar B2 is vertically hatched. In a basic position, both bars B1 and B2 overlap in the center of the optically variable surface pattern 10, whereby in Fig. 5B The diagram, which shows this basic position, does not depict an exact superimposition for clarity. When tilting in a first direction, for example, the magenta bar B1 can move upwards and the green bar B2 downwards, as shown in Fig. 5C as indicated by the arrows P1 and P2. When tilted in the opposite direction, the two bars move in the opposite direction, i.e., the magenta bar B1 moves downwards and the green bar B2 moves upwards ( Fig. 5A ), where the directions of movement are indicated by the arrows P1 and P2.

[0058] To achieve this movement effect, the inclination α of the micromirrors 14 can be varied in the desired direction of movement, as shown schematically in the sectional view in Fig. 6 shown is a cut in the direction of arrow P1 according to Fig. 5A Figure 14 shows two adjacent micromirrors. The indicated inclination angles α1 and α2 differ, with the inclination angle α increasing from bottom to top.

[0059] The described "rolling bar" effect is an example of a two-color overlapping running effect that can be achieved with the optical surface pattern according to the invention. Other running effects are also possible, of course. In particular, so-called flip, running, and / or pumping effects can be achieved by tilting the optically variable surface pattern; these effects can be synchronous or counter-rotating.

[0060] Furthermore, a pumping effect can be implemented, in which the outline of a symbol or numerical value "pumps" inwards or outwards. Repeating pumping effects with many simultaneously visible outlines are particularly attractive, as they can then light up in very subtle, different colors under the right viewing angle.

[0061] The micromirror array 14 can be embedded in a medium 18 that has a similar refractive index to the embossed lacquer layer 16 or the coating 17, as shown in Fig. 7 This is shown. This locally cancels the refraction at the top of the relief structure, causing the directions of the first and second reflected light rays L2' and L3' from areas with medium 18 to differ from the directions of the first and second light rays L2, L3 from areas without medium 18. This is primarily because medium 18 cancels the refractive effects for the second reflected light ray L3' and adds refractive effects for the first reflected light ray L2'. How Fig. 7 As can be seen in detail, in the area with the medium 18, the first reflected light ray L2' is also refracted at the top of the layer 18 and therefore generally travels in a different direction than the first light ray L2 from the area without coating 18. The second light ray L3' from the area with coating 18 is always visible in the specular reflection of the reflective layer 15 and therefore travels in a different direction than the second light ray L3 from the area without coating 18.

[0062] Furthermore, the optically variable surface pattern 10 can be designed, for example, such that the first reflected light ray L2 is green and the refracted and downwardly reflected second light ray L3 is magenta. If the slopes of the micromirrors 14 are then chosen such that they are in the regions 21 and 22 according to Fig. 3 Since the refraction-canceling coating 18 is applied to the top surface of the optically variable surface pattern 10 in area 22, the following optical effects are achieved. Area 22 is clearly visible at two different first angles. It appears green due to light rays L2' and magenta due to light rays L3'. Area 21 is visible at two further angles in green (due to light rays L2) and magenta (light rays L3). Because the coating 18 has a similar or ideally the same refractive index as the coating 17, the special feature here is that the reflection direction of the second light ray L3' always corresponds to a specular reflection at the reflective layer 15 (regardless of the inclination α of the micromirrors 14). Area 22 thus illuminates in the specular reflection of the reflective layer 15, i.e., always as a homogeneous magenta area, even if the micromirrors 14 in this area are, for example,exhibit varying orientations.

[0063] The structuring of the side of the embossed lacquer layer 16 facing away from the reflective layer 15 to form the micromirrors 14 can be regular or irregular. In particular, periodic or aperiodic sawtooth structures are possible.

[0064] For example, no coating 17 can be provided on the embossing lacquer layer 16. In this case, there is an interface between the embossing lacquer layer 16 and air. The embossing lacquer of the embossing lacquer layer 16 can preferably be a high-refractive-index embossing lacquer. Of course, the layer 16 does not have to be an embossing lacquer layer, but can also be any other transparent or semi-transparent layer with a structured surface or with a relief structure on the surface.

[0065] The coating 17 can be a dielectric coating, in particular a high-refractive-index coating or a low-refractive-index coating on high-refractive-index embossing lacquer 16. A multilayer thin-film system (metal / dielectric / metal) or a purely dielectric multilayer system is also possible. Furthermore, the coating 17 can be designed as a liquid crystal layer. The surface of the micromirrors 14 can also be designed with color-imparting embossing structures and / or nanostructures (e.g., semi-transparent metallized subwavelength structures, in particular subwavelength gratings).

[0066] The reflective layer 15 can, for example, be designed as a liquid crystal layer (advantageously against a dark background). It is also possible to incorporate color-generating nanostructures (e.g., subwavelength structures, especially subwavelength gratings), photonic crystals, thin-film color shift, or simple metallization (e.g., Al, Au, Cu, Cr, ...).

[0067] The reflective layer 15 can be partially transparent, so that the optically variable surface pattern 10 according to the invention can also have an optically variable effect visible from the underside (through transmission through the reflective layer 15, reflection at the micromirrors 14 and renewed transmission through the partially transparent lower reflective layer 15 back to the rear).

[0068] The optically variable surface pattern 10 according to the invention can be designed such that the two reflected light rays L2 and L3 appear (in particular approximately) equally bright and / or have different colors (in particular complementary colors). For example, the coating 17 can reflect a first color particularly strongly and simultaneously transmit the complementary color to a high degree. The complementary color is then reflected at the reflective layer 15. In this case, dielectric layers, multilayers, or liquid crystal layers are particularly suitable for the coating 17, in which the incident light can be split into reflected and transmitted light largely without absorption loss.Furthermore, the optically variable surface pattern 10 can be designed such that one of the two reflected light rays L2, L3 appears colorless (white), where white is also referred to as color in the sense of the present invention.

[0069] To protect the micromirrors 14 from being molded, they can be embedded (for example, the embossing lacquer layer 16 can have a higher refractive index than the layer intended for embedding, which could be a protective lacquer layer). However, it is also possible that the embedding layer has a higher refractive index than the embossing lacquer layer 16.

[0070] Furthermore, a protective film can be provided, selected to preserve the refractive effect of the micromirrors 14 and prevent it from being destroyed, for example, by a laminating adhesive with a similar refractive index. The protective film can be spot-welded (e.g., with a laser), glued on, etc., to prevent air or gas inclusions. It is also possible to use a high-refractive-index embossing varnish or, for example, to omit the laminating adhesive for the protective film in the area of ​​the optically variable surface pattern.

[0071] The optically variable surface pattern according to the invention is preferably manufactured and / or used on a carrier film. The carrier film can be arranged, in particular, below the reflective layer 15, between the reflective layer 15 and the embossed lacquer layer 16 or the micromirrors 14, or above the micromirrors 14.

[0072] The reflective layer 15 and the coating 17 can be partially omitted, e.g., in the same or different, overlapping or non-overlapping areas. The corresponding colors or effects are then only visible in those areas.

[0073] The micromirrors 14 can advantageously be embossed into a colored embossing varnish 16. This allows for the relatively cost-effective generation of colors for the refracted and downwardly reflected second light ray L3. Alternatively, a separate colored layer 23 (e.g., a varnish layer) can be provided between the micromirrors 14 made of transparent embossing varnish and the reflective layer 15, as shown in Fig. 8 shown.

[0074] The optically variable surface pattern 10 according to the invention can also be used as a safety thread 12 ( Figur 1) be formed. Furthermore, the optically variable surface pattern 10 can not only be formed on a carrier film, as described, from which it can be transferred to the security document in a known manner. It is also possible to form the optically variable surface pattern 10 directly on the security document. Thus, direct printing followed by embossing of the micromirrors onto a polymer substrate can be carried out to form, for example, an optically variable surface pattern according to the invention in plastic banknotes. The optically variable surface pattern according to the invention can be formed in a wide variety of substrates. In particular, it can be formed in or on a paper substrate, a paper with synthetic fibers, i.e., paper with a proportion x of polymeric material in the range of 0 < x < 100 wt.%, a plastic film, e.g.a film made of polyethylene (PE), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polypropylene (PP) or polyamide (PA), or a multilayer composite, in particular a composite of several different films (composite composite) or a paper-film composite (film / paper / film or paper / film / paper), wherein the optically variable surface pattern can be provided in or on or between each of the layers of such a multilayer composite.

Claims

1. An optically variable surface pattern (10) for use as a security feature to be applied to an object to be protected, comprising a reflective layer (15) and a micromirror array (20) formed on the reflective layer (15), which comprises a plurality of partially transparent micromirrors (14), wherein light (L1) incident on the micromirror array is partially reflected in a first direction by reflection at the partially transparent micromirrors and is partially reflected in a second direction different from the first direction by passing through the partially transparent micromirrors (14), striking the reflective layer (15), is reflected there, and then passes through the partially transparent micromirrors again, wherein the micromirrors (14) are configured such that a relief structure with essentially ray-optical effects is present, which causes the reflection of the incident light in the first direction, and wherein the reflective layer (15) and the micromirror array (20) are configured such that the light (L2, L3) reflected in the first and second directions has different colors, wherein a transparent or partially transparent layer (16) is formed on the reflective layer (15), wherein, for the formationthe microspecular mirrors, the side of the transparent or partially transparent layer (16) facing away from the reflective layer (15) is patterned in a predetermined area, wherein the transparent or partially transparent layer (16) is formed by an embossed lacquer layer, characterized in that the optically variable surface pattern (10) is configured such that, when the surface pattern is tilted, a first motion effect is produced with the light rays reflected in the first direction and a second motion effect is produced with the light rays reflected in the second direction.

2. An optically variable surface pattern (10) according to claim 1, in which the structure of the transparent or partially transparent layer (16) is formed by embossing.

3. An optically variable surface pattern (10) according to claim 1 or 2, wherein the partially transparent micromirrors (14) form a sawtooth-shaped profile.

4. An optically variable surface pattern (10) according to any one of claims 1 through 3, wherein the patterning on the side of the transparent or partially transparent layer (16) facing away from the reflective layer (15) is regular, for the purpose of forming the micromirrors.

5. An optically variable surface pattern (10) according to any one of claims 1 through 4, wherein a partially transparent color layer is disposed between the reflective layer (15) and the transparent or partially transparent layer (16).

6. An optically variable surface pattern (10) according to any one of claims 1 through 4, wherein the reflective layer (15) and the micromirror array (20) are configured such that the light reflected in the first direction or the light reflected in the second direction appears white.

7. An optically variable surface pattern (10) according to any one of claims 1 through 6, wherein the partially reflective surfaces of the micromirrors (14), which cause the incident light to be reflected in the first direction, are curved, in particular concave, convex, or wavy.

8. An optically variable surface pattern (10) according to claim 1, wherein the second motion effect has the same or an opposite direction of motion and the same or a different speed of motion.

9. An optically variable surface pattern (10) according to any one of claims 1 through 8, wherein the transparent or partially transparent layer (16) has a refractive index of at least 1.6, preferably at least 1.8, in at least a portion of the visible spectrum.

10. An optically variable surface pattern (10) according to any one of the preceding claims, wherein the side of the reflective layer (15) facing the partially transparent micromirrors (14) and / or the side of the reflective layer (15) facing away from the partially transparent micromirrors (14) is / are flat.

11. An optically variable surface pattern (10) according to any of the preceding claims, in which a plurality of the partially transparent micromirrors (14) are arranged side by side in an arrangement direction and their dimension in the arrangement direction is in the range of 2 µm to 3 mm, preferably from 3 µm to 100 µm, and most preferably from 5 µm to 30 µm.

12. An optically variable surface pattern (10) according to one of the preceding claims, in which, when light is incident perpendicularly, the first and second directions of the reflected light lie on different sides of the macroscopic surface normal of the optically variable surface pattern.

13. An optically variable surface pattern (10) according to any of the preceding claims, wherein the reflective layer (15) comprises one or more metallic layers, a thin-film color-shift layer, one or more dielectric layers, and / or a liquid-crystalline layer, in particular a liquid-crystalline layer on a dark background.

14. An optically variable surface pattern (10) according to any of the preceding claims, wherein the reflective layer is present in the form of patterns, characters, or codes and / or comprises recesses in the form of patterns, characters, or codes.

15. Use of the optically variable surface pattern (10) according to any of the preceding claims as a security feature, in particular as a security feature for security papers, valuable documents, or the like.

16. A security document (11) comprising an optically variable surface pattern (10) according to any one of claims 1 through 14.