EP3233512B1 - Optically variable transparent security element - Google Patents
Optically variable transparent security element Download PDFInfo
- Publication number
- EP3233512B1 EP3233512B1 EP15804317.4A EP15804317A EP3233512B1 EP 3233512 B1 EP3233512 B1 EP 3233512B1 EP 15804317 A EP15804317 A EP 15804317A EP 3233512 B1 EP3233512 B1 EP 3233512B1
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- European Patent Office
- Prior art keywords
- facets
- color
- security element
- optically variable
- subregions
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- B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
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- B—PERFORMING OPERATIONS; TRANSPORTING
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- B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
- B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
- B42D25/20—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof characterised by a particular use or purpose
- B42D25/29—Securities; Bank notes
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
- B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
- B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
- B42D25/30—Identification or security features, e.g. for preventing forgery
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- B—PERFORMING OPERATIONS; TRANSPORTING
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- B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
- B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
- B42D25/30—Identification or security features, e.g. for preventing forgery
- B42D25/351—Translucent or partly translucent parts, e.g. windows
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
- B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
- B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
- B42D25/30—Identification or security features, e.g. for preventing forgery
- B42D25/36—Identification or security features, e.g. for preventing forgery comprising special materials
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- B—PERFORMING OPERATIONS; TRANSPORTING
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- B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
- B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
- B42D25/30—Identification or security features, e.g. for preventing forgery
- B42D25/36—Identification or security features, e.g. for preventing forgery comprising special materials
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- B—PERFORMING OPERATIONS; TRANSPORTING
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- B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
- B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
- B42D25/30—Identification or security features, e.g. for preventing forgery
- B42D25/36—Identification or security features, e.g. for preventing forgery comprising special materials
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- B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
- B42D25/40—Manufacture
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Definitions
- the invention relates to an optically variable see-through security element for securing valuables, having a planar, optically variable surface pattern, which shows a colored appearance with a viewing angle-dependent multicolor color change.
- Data carriers such as valuables or identity documents, but also other valuables, such as branded goods, are often provided with security elements for the purpose of security, which permit verification of the authenticity of the data carrier and at the same time serve as protection against unauthorized reproduction.
- security elements for the purpose of security, which permit verification of the authenticity of the data carrier and at the same time serve as protection against unauthorized reproduction.
- the perceived color depends not only on the viewing angle to the security element, but also on the direction to the light source, and also a corresponding security element for viewing the diffraction colors of the first order not directly in front of a light source may be held, but the security element must be kept something out of the direct line of connection.
- the security element when the security element is tilted, all the rainbow colors are passed through, so that the color changes that occur are largely undefined and the observed color effects are often simply perceived by the untrained viewer as colorful.
- holographic techniques are now also used outside the security area and therefore offer only limited protection against counterfeiting.
- thin-film systems produce colors that change as a function of viewing angle due to interference in reflected light and transmitted light.
- Different colors are usually realized by a variation of the layer thicknesses, for example the thickness of a dielectric spacer layer in a three-layer structure absorber / dielectric / absorber.
- the adjustment of a desired color on the adaptation of the layer thicknesses is technologically very expensive.
- One possibility is to print one or more dielectric layers in sections, but very high demands are placed on the uniformity of the printed layers and the lateral resolution is limited to the resolution achievable with the corresponding printing methods.
- motif changes when tilting with such thin film systems are practically unrealizable.
- a further solution consists of producing colors with transparent or semitransparently coated subwavelength structures in the transmitted and transmitted light which change when the structures are tilted.
- DE 10 2009 053 925 A1 relates to a security element according to the preamble of claim 1, wherein through an opaque louver-like structure through an underlying motif image in view viewing angle is dependent visible or not visible.
- an additional motif may be different by area Orientation of the shutter elements are displayed.
- an additional motif may be formed by a thin-film element on the opaque layer. Proceeding from this, the present invention seeks to provide a see-through security element of the type mentioned, which avoids the disadvantages of the prior art.
- the see-through security element should combine an appealing visual appearance with high security against counterfeiting and ideally be able to be produced in the commercial scale required in the security area.
- the facets of a subarea have not only the same orientation but also the same shape and size.
- the area occupied by each subarea on the optically variable surface pattern is in advantageous embodiments at least 50 times, preferably at least 100 times, more preferably at least 1000 times larger than the area occupied by a single facet of this surface area on average.
- the sections usually contain a very large number of individual facets.
- the facets of the at least two partial regions differ in inclination angle against the plane by 5 ° or more, preferably by 10 ° or more, particularly preferably by 20 ° or more.
- the facets of the at least two partial regions differ in the azimuth angle in the plane by 45 ° or more, preferably by 90 ° or more, in particular by 180 °.
- the facets of the surface pattern are preferably formed by flat surface pieces, which are each characterized by their shape, size and orientation.
- the orientation of a facet is indicated by the inclination ⁇ against the plane of the surface pattern and by an azimuth angle ⁇ in the plane of the surface pattern.
- the azimuth angle ⁇ is the angle between the projection of the normal vector of the facet on the plane of the surface pattern and a reference direction in the plane. Since the azimuth angle ⁇ depends on the choice of the reference direction, its absolute value has no meaning, but the difference of the azimuth angle of different sub-ranges, since this describes the different relative orientation of the facets in the associated sub-areas.
- the dimension of the facets is preferably so large that no or hardly diffraction effects occur, so that the facets essentially act only radiation-optical.
- the facets advantageously have a smallest dimension of more than 2 ⁇ m, preferably more than 5 ⁇ m, in particular more than 10 ⁇ m.
- the facets preferably have a height below 100 ⁇ m, preferably below 50 ⁇ m, in particular below 10 ⁇ m.
- the facets can be arranged regularly, for example in the form of a 1- or 2-dimensional periodic grid, for example a sawtooth grid, or else aperiodically.
- Another possibility to suppress unwanted diffraction effects is to aperiodically offset the facets in their height above the surface area.
- an aperiodic displacement of the facets there is no simple, regular relationship between the heights of adjacent facets, so that constructive interference of the light reflected at neighboring facets and thus the emergence of a superimposed diffraction pattern are reliably prevented. Details of such aperiodic displacement of the document WO 2012/055506 A1 are removed, the disclosure content of which is included in the present application in this respect.
- a first example of an advantageous interference layer is a thin-film element with semitransparent metal layers and a dielectric spacer layer, in particular with a structure absorber / dielectric / absorber, wherein for example metals such as Ag, Au, Cr or Al can be used as absorber layers and SiO 2 , MgF 2 or polymers can be used as the dielectric layer.
- Dielectric layer systems, in particular multilayer systems are also suitable as interference layer, in particular layer structures with at least one high-index layer, such as TiO 2 or ZnS, preferably combined with at least one low-index layer, such as SiO 2 or MgF 2 .
- the thin-film element may also contain semiconductive layers, such as Si, for example, a thin-film structure of the Si / SiO 2 / Si layer sequence may be used.
- semiconductive layers such as Si
- dielectric spacer layers it is also possible, for example, to use polymers instead of oxides.
- liquid-crystalline layers in particular with color-changing cholesteric liquid crystals, as the interference layer.
- the entire optically variable surface pattern is advantageously provided with the same interference layer, which is applied simultaneously to all facets.
- the interference layer can be further structured by subsequent process steps in order to produce interference-layer-free regions.
- the interference layer depending on the inclination of the facets may have a locally different thickness, as explained in more detail below.
- the interference layer has a layer thickness which does not depend significantly on the angle of inclination of the coated facets.
- a substantially constant layer thickness can be achieved, for example, with non-directional coating methods be achieved or results in a coating with cholesteric liquid crystals in the form of constant distances of the planes with the same refractive index.
- the facets are provided with an interference layer whose layer thickness varies with the inclination angle ⁇ of the facets, in particular decreases with increasing inclination angle ⁇ .
- the present inventors have surprisingly found that such an interference layer can produce particularly strong color differences between facets of different inclinations.
- a particularly large color palette for the colored appearances is available, which even allows the production of true color images, on the other hand can be realized in this way strong color change when tilting the surface pattern.
- Such a varying layer thickness of the interference layer can be achieved, for example, by directional coating methods, such as vacuum evaporation methods. In such processes, the angle of inclination of the facets leads to an increase in the effective surface area, so that less material per unit area is deposited on inclined facets, and the resulting layer thickness thus strongly depends on the angle of inclination of the facets.
- the facets are advantageously embossed in an embossing lacquer layer having a first refractive index.
- a lacquer layer having a second refractive index which differs from the first refractive index of the embossing lacquer layer by less than 0.3, in particular by less than 0.1, is applied over the interference layer. Due to this essentially identical refractive index of the two paint layers, incident light traverses the security element independently of the local inclination angle ⁇ of the facets essentially without directional deflection, thus ensuring a uniform distribution of brightness in the plane of the surface pattern.
- the at least two partial regions are arranged in the form of a motif, wherein the optically variable surface pattern shows the motif formed by the partial regions in review, at least in certain tilted positions of the security element with two or more different colors.
- the inclination angles ⁇ and the azimuth angles ⁇ of the facets and the interference layer in the two subregions are advantageously matched to one another in such a way that the subregions display the same colors in a certain tilted position and different colors in other tilted positions.
- the security element shows a motif that arises when tilted from a homogeneous appearing surface or disappears into a seemingly homogeneous surface.
- both the inclination angles ⁇ of the facets, the azimuth angles ⁇ of the facets and the interference layer must be coordinated in the subregions such that the desired color effect is achieved.
- the optically variable surface pattern advantageously contains at least two partial regions in which the facets have the same inclination angle a but azimuth angles ⁇ differing by 180 °.
- the inclination angles ⁇ are advantageously greater than 5 °, particularly preferably greater than 10 °, and are for example 15 °, 20 ° or 25 °.
- the optically variable surface pattern contains at least four partial regions, it is advantageously provided that the optically variable surface pattern contains a first and second partial region in which the facets have the same inclination angle ao but azimuth angles ⁇ differing by 180 °, and further a third and fourth sub-area, in which the facets have different inclination angles ⁇ 1 and ⁇ 2 and in which the azimuth angle ⁇ differs by 90 ° or 270 ° from the azimuth angle of the first and second sub-area.
- the inclination angles ⁇ 0 are advantageously greater than 5 °, particularly preferably greater than 10 °, and are for example 15 °, 20 ° or 25 °. As explained in more detail below, can be realized in this way in a particularly simple manner, a tilt image with two different motifs.
- tilt images with two different, even overlapping motifs can already be realized with an optically variable surface pattern with only three partial areas.
- this usually requires an interleaving of the subregions assigned to the motifs, in which, as described in more detail below, the surface pattern is decomposed into narrow strips or small pixels.
- the optically variable surface pattern contains at least three subregions in which the inclination angle ⁇ and the azimuth angle ⁇ of the facets and the interference layer are matched to one another so that the subregions appear in a tilted position as viewed in red, green or blue.
- these colors are not tipped Security element, that is generated in vertical viewing.
- the optically variable surface pattern may additionally have in the subregions a black mask which has been matched to the inclined facets and which serves to adjust the translucent brightness of the facets in the respective subregions.
- the three subareas may, optionally together with the black mask, thereby advantageously represent the color separations of a true color image. In this way can be displayed in the selected tilt position in perspective realistic appearing true color images.
- the invention also includes a data carrier with a see-through security element of the type described, wherein the see-through security element is preferably arranged in or over a window region or a through opening of the data carrier.
- the data carrier may in particular be a value document, such as a banknote, in particular a paper banknote, a polymer banknote or a film composite banknote, but also an identity card, such as a credit card, bank card, cash card, authorization card, identity card or a Trade personalization page.
- the invention further includes a method of fabricating an optically variable see-through security element in which a substrate is provided and the substrate is provided with a planar, optically variable area pattern which shows in phantom a colored appearance with a viewing angle dependent multicolor color change.
- the optically variable surface pattern is generated with a plurality of substantially radiation-optical facets whose orientation is in each case by an inclination angle ⁇ against the plane of the surface pattern, which lies between 0 ° and 45 °, and by a Azimuth angle ⁇ is characterized in the plane of the surface pattern, the facets are provided with an interference layer with a viewing angle-dependent color change, and the optically variable surface pattern is generated with at least two subregions, each having a plurality of identically oriented facets, wherein the facets of the at least two Divide sections from each other in the angle of inclination against the plane and / or in the azimuth angle in the plane.
- the facets are coated with the interference layer in a directional coating process, in particular in a vacuum vapor deposition process.
- Fig. 1 shows a schematic representation of a banknote 10 with an optically variable see-through security element 12 according to the invention, which is arranged over a continuous opening 14 of the banknote 10.
- the security element 12 shows in phantom a colored appearance with a motif 16, 18 which has a viewing angle-dependent multicolor color change.
- Fig. 1 shows the security element 12 in a vertical viewing perspective, a homogeneous, monochrome yellow area in which the value "10" of the foreground area 16 is not recognizable because of the lack of color difference to the background 18.
- the security element 12 is tilted to the right or left (reference numerals 20-R, 20-L) and viewed at an oblique angle, the colors of the foreground 16 and the background 18 change in different ways, so that the value "10" clearly stands out in the tilted position due to the color difference.
- the see-through color of the background area 18 changes from yellow to green
- the see-through color of the foreground area 16 changes from yellow to red.
- Tilting to the left 20-L results in reverse color changes, that is, the see-through color of the background area 18 changes from yellow to red, while the see-through color of the foreground area 16 changes from yellow to green.
- the security element 12 thus shows in review from different viewing directions very different visual appearances, which is unexpected especially for transparency elements for the viewer and therefore has a high attention and recognition value.
- Fig. 2 schematically shows the layer structure of the security element 12 according to the invention in cross section, wherein only the parts of the layer structure required for the explanation of the principle of operation are shown.
- the security element 12 has a planar, optically variable surface pattern which contains a multiplicity of essentially radiation-optical facets 32.
- the facets 32 are formed by flat surface pieces and are each characterized by their shape, size and orientation.
- the orientation of a facet 32 is indicated by the inclination ⁇ to the plane 30 of the surface area and by an azimuth angle ⁇ in the plane 30, the azimuth angle ⁇ being the angle between the projection of the normal vector 46, 48 of a facet 32 the level 30 and a reference direction is Ref.
- the azimuth angles ⁇ differ, however, by 180 °, so that the facets 32 are tilted to the left in the partial region 16, while the facets 32 are tilted to the left are tilted in the partial area 18 to the right.
- the facets 32 of the surface pattern are embossed into a preferably transparent embossing lacquer 34 and, in the exemplary embodiment, have a square outline with a dimension of 20 ⁇ m ⁇ 20 ⁇ m.
- the facets 32 are further provided with an almost transparent or at least semitransparent interference coating 36 which, when viewed, produces a color impression dependent on the viewing angle.
- the interference coating 36 may be formed, for example, of a three-layer thin-film structure having two metallic semitransparent layers, such as aluminum, silver, chromium, gold, or copper, and an intervening dielectric spacer layer, such as SiO 2 , MgF 2, or a polymer.
- the thickness of the interference coating 36 is independent of the inclination angle ⁇ of the facets 32.
- a further resist layer 38 is applied, which has substantially the same refractive index as the resist layer 34, which ensures that incident light passes through the layer sequence of the security element 12 regardless of the local inclination angle ⁇ of the facets 32 substantially without directional deflection and thus a uniform Brightness distribution generated in the plane of the surface pattern.
- the interference coating 36 of the facets produces a color impression in transmitted light that depends on both the direction of incidence of the light relative to the plane normal of the optically variable area pattern and the individual inclination angle of the facets 32, since both factors influence the angle of incidence of the light relative to the normal of the interference coating 36 ,
- Fig. 3 schematically shows a calculated color spectrum of facets 32 with a three-layer interference coating 36 having a first, 25 nm thick silver layer, a SiO 2 spacer layer of thickness d and a second, 25 nm thick silver layer.
- the transparency is initially outside the visible spectral range and then changes to blue (B), green (G) and yellow (Y) to red (R) for spacer layers with layer thicknesses in the range of about 130 nm After a region without visible see-through color, this sequence is repeated at higher layer thicknesses from 200 nm to about 350 nm.
- the interference coating 36 therefore generates a red transmission color in the partial region 16.
- the interference coating 36 therefore produces a green see-through color in the subregion 18.
- the monochrome homogeneous color impression at normal incidence of light in Fig. 4 (a) is a consequence of the equality of the inclination angle ⁇ in the two sub-areas 16,18 with simultaneous azimuth angle difference of 180 °.
- a security element 60 according to the invention can also show a tilted image in which different motifs are visible in different tilt positions, as is now the case with reference to FIG Fig. 5 explained.
- Fig. 5 (a) first shows in plan the division of the optically variable surface pattern of the security element 60 into three sub-areas 62, 64, 66, which are arranged in the form of a background area 62, a first foreground area 64 (triangle) and a second foreground area 66 (circle).
- Fig. 5 further shows in (b) to (d) the security element 60 in cross section in different tilted positions.
- the security element 60 is basically like the security element 12 of Fig. 2
- this tilted position only the motif of the second foreground region 66 is visible, since the motif of the first foreground region 64 merges with the background region 62 in the same color.
- the first and second foreground areas now exchange their roles.
- ⁇ 10 °
- FIG Background area 62 generates a yellow transparency (the background color).
- the foreground regions 64, 66 are spatially separated from each other in the plane of the surface pattern, and thus have no overlap. If tipping motives are to be realized with overlaps, this can be achieved, for example, by interleaving the subareas assigned to the motifs.
- the surface pattern is decomposed into narrow strips or small pixels, alternately the first foreground motif 64 and the background motif 62 on the one hand and the second foreground motif 66 on the other hand and the background image 62 included.
- the dimensions of the small strips or pixels are in particular below 300 .mu.m or even below 100 .mu.m, so that the division of the surface pattern with the naked eye is not recognizable or at least not noticeable.
- the interleaving of overlapping representations with three subregions with different facet orientations usually leads to the fact that the chroma or the contrast of the see-through colors does not reach the maximum possible values, since the interleaving can in part only produce mixed colors, and mixed colors in general have a lower chroma than the original colors.
- the optically variable area pattern is divided into four subareas 82, 84, 86, 88, which are in the form of a background area 82, a first foreground area 84 (square without circle segment 88), a second foreground area 86 (circular disk without circle segment 88) and an overlap region 88 (circle segment) are arranged.
- the first foreground area 84 forms, together with the circle segment 88, the complete square as the first motif to be displayed
- the second foreground area 86 together with the circle segment 88 as the second motif to be represented forms the complete circular disk.
- the inclinations and azimuth angles of the facets in the four subregions are selected so that the security element 80 in a first tilted position in the transmitted light as the first motif to be displayed the complete square (first foreground area 84 and circle segment 88 together) with a uniform subject color and the remaining area pattern ( second foreground area 86 and background area 82) with a background color different from the subject color.
- the security element 80 shows in transmitted light as the second motif to be displayed the complete circle (second foreground area 86 and circle segment 88 together) with the uniform subject color, while the remaining area pattern (first foreground area 84 and background area 82) appears with the background color.
- the inclination and the azimuth angle of the facets in the background region 82 are thus selected such that they produce the background color both in the first and in the second tilt position.
- the slope and azimuth angle of the facets in the first foreground area 84 are selected such that they produce the motif color in the first tilted position and the background color in the second tilted position, while the facets in the second foreground region 86 are selected such that they produce the background color in the first tilted position and the subject color in the second tilted position.
- the inclination and the azimuth angle of the facets are selected such that they produce the motif color both in the first and in the second tilt position.
- the required inclinations and azimuth angles in the various subregions can be determined, for example, by the following procedure, wherein it is concretely assumed that the first tilted position results from a tilting 90-0 of the security element 80 upwards at a certain angle, while the second tilted position by tilting 90-U of the security element 80 by the same angle down.
- the angle of inclination ⁇ that angle is defined for both foreground areas, which generates the desired subject color when the mirrors are inclined upwards or downwards in the first or second tilted position. This essentially corresponds to that already related to Fig. 2 described procedure.
- the projections of the normal vectors of the facets are also drawn onto the plane of the surface pattern.
- the facets in the portions 84, 86 have the same inclination angles ⁇ , while the azimuth angles ⁇ differ by 180 °. Because of the symmetry of the arrangement, this ensures that the first foreground area 84 in the first tilted position shows the same see-through color (subject color) as the second foreground area 86 in the second tilted position.
- the first foreground area 84 shows the background color in the second tilted position, as does the second foreground area 86 in the first tilted position.
- angles of inclination coated with the selected interference coating facets at an azimuth angle of 0 ° or 180 ° in the first tilt position, the subject color or the background color were also determined in a series of experiments at which angles of inclination coated with the selected interference coating facets at an azimuth angle of 0 ° or 180 ° in the first tilt position, the subject color or the background color.
- These angles of inclination generally depend on the type of interference coating, the dependence of the interference layer thickness on the angle of inclination of the facets and the refractive indices of the embedding lacquer layers, but can easily be determined by a simple series of experiments. For example, it follows that the facets in the first tilt position at an azimuth angle of 0 ° and an inclination angle ⁇ M show the subject color and at an inclination angle ⁇ H show the background color. Because of the symmetry of the arrangement is then ensured that the facets this Show colors even in the second tilted position, as this is achieved by tilting the security element by the same
- the thickness of the interference coating was independent of the tilt angle of the facets.
- Fig. 7 schematically shows a calculated color spectrum of coated facets at normal incidence of light on the plane of the surface pattern, wherein the interference coating by a three-layer interference coating with a first 25 nm thick silver layer, a SiO 2 spacer layer of nominal thickness do and a second, also 25 nm thick silver layer is formed.
- the nominal thickness d 0 is plotted on the abscissa, while the inclination angle ⁇ of the facets is plotted on the ordinate.
- the pitch-dependent layer thickness significantly greater color differences are achieved. Since facets of different inclinations can be produced simply by embossing into an embossing lacquer layer 34, subareas of very different colors can be arranged with a high accuracy of a few micrometers to each other.
- inventions described above can be realized not only with interference coating constant thickness, but advantageously also with an interference coating with tilt-dependent thickness, which can be generated, for example, tilt images with particularly strong color contrasts.
- any color can be represented as additive color mixing of these three primary colors.
- the subregions are formed for this purpose, for example, as in a conventional RGB display in the form of small pixels or stripes.
- the brightness of the color areas in the individual pixels must be able to be specifically adjusted.
- the color areas of individual pixels can be overprinted black or coated with an opaque metallization, the technological challenge being the exact registration of overprinting or of the coating.
- FIG. 8 shows in (a) to (e) in cross section various intermediate stages in the production of the optically variable surface pattern 110, wherein only a small portion of the surface pattern is shown, namely just a single color pixel 112 with a red color range 114-R, a green color range 114-G and one blue color range 114-B.
- the size of the color pixel 112 is, for example, 100 ⁇ m ⁇ 100 ⁇ m.
- elevations 116 are provided which later form the black area for each color area and whose area ratio to the facets is selected according to the desired brightness of the respective color area. If, for example, the red component in the color pixel 112 shown is to have a brightness of 70%, the facets occupy 70% and the elevations 30% of the total area of the color region 112-R.
- the embossed lacquer layer 34 as in Fig. 8 (b) shown, over the entire surface with the selected interference coating 36 provided, such as the above-mentioned three-layer system of a first 25 nm thick silver layer, a nominally 330 nm thick SiO 2 spacer layer and a second 25 nm thick silver layer.
- the selected interference coating 36 provided, such as the above-mentioned three-layer system of a first 25 nm thick silver layer, a nominally 330 nm thick SiO 2 spacer layer and a second 25 nm thick silver layer.
- At least the SiO 2 spacer layer is produced by directional coating methods, for example by vertical vapor deposition, so that the described dependence of the actual layer thickness of the spacer layer on the angle of inclination ⁇ of the facets is established.
- the interference coating 36 removed only on the elevations 116.
- This can be done for example with a metal transfer method, as described in the document DE 10 2010 019 766 A1
- an etch resist may be printed over the entire surface of the coated resist layer and doctored so that the resist remains only in the faceted depressions and the interference coating 36 may be etched away from the non-resist covered bumps.
- a blackened photoresist 118 is applied to the opposite side of the surface pattern as in FIG Fig. 8 (d) and exposed from the upper side through the partially coated surface pattern (reference numeral 120) as shown in FIG Fig. 8 (e) shown.
- the exposure dose is chosen so that the photoresist is removed during the exposure by the interference layer during development, the remains of the elevations 116 without interference layer exposed photoresist but stops.
- a black mask 122 is obtained in this way on the back of the surface pattern, which is blackened exactly at the locations where there are no facets 32 provided with an interference layer 36, as in FIG Fig. 8 (f) shown.
- the surface pattern of Fig. 8 (f) is then further processed by further process steps to the finished security element, for example by applying a further lacquer layer 38 to the interference coating 36 and by applying further protective or functional layers.
- an auxiliary layer for example an opaque aluminum layer, which only serves to structure the photoresist 118, is also initially applied. After patterning the photoresist 118 to create the black mask in the step of Fig. 8 (f) the auxiliary layer is completely removed and the desired interference layer 36 is applied over the entire surface.
- This variant offers the advantage that the interference coating neither in the exposure step ( Fig. 8 (e) ) can serve as a reliable exposure mask, nor that the interference coating etched away well ( Fig. 8 (c) ) must be. Rather, an auxiliary layer optimized for these requirements can be selected, while the interference coating is selected only on the basis of the desired coloring properties.
- the black mask can also be produced by other methods, for example by metal transfer methods, etching methods or else directly or indirectly via laser ablation controlled by embossed structures.
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Description
Die Erfindung betrifft ein optisch variables Durchsichtssicherheitselement zur Absicherung von Wertgegenständen, mit einem ebenen, optisch variablen Flächenmuster, das in Durchsicht ein farbiges Erscheinungsbild mit einem betrachtungswinkelabhängigen mehrfarbigen Farbwechsel zeigt.The invention relates to an optically variable see-through security element for securing valuables, having a planar, optically variable surface pattern, which shows a colored appearance with a viewing angle-dependent multicolor color change.
Datenträger, wie Wert- oder Ausweisdokumente, aber auch andere Wertgegenstände, wie etwa Markenartikel, werden zur Absicherung oft mit Sicherheitselementen versehen, die eine Überprüfung der Echtheit des Datenträgers gestatten und die zugleich als Schutz vor unerlaubter Reproduktion dienen. Dabei gewinnen zunehmend Durchsichtssicherheitsmerkmale, wie etwa Durchsichtsfenster in Banknoten, an Attraktivität.Data carriers, such as valuables or identity documents, but also other valuables, such as branded goods, are often provided with security elements for the purpose of security, which permit verification of the authenticity of the data carrier and at the same time serve as protection against unauthorized reproduction. Increasingly transparent security features, such as transparent windows in banknotes, are becoming increasingly attractive.
Herkömmliche transparente oder semitransparente Sicherheitselemente mit einem betrachtungswinkelabhängigen mehrfarbigen Farbwechsel im Durchlicht weisen allerdings verschiedene Nachteile auf. So ist etwa bekannt, mit transparent oder semitransparent beschichteten Hologrammgittern oder Transmissionsgittern im Durchlicht Beugungsfarben zu erzeugen, wobei durch geeignete Wahl der Gitterperioden und der Azimutwinkel der Gitter erreicht werden kann, dass unter verschiedenen Betrachtungswinkeln unterschiedliche Darstellungen mit sich ändernden Farben entstehen. Das Erscheinungsbild solcher Gitterbilder hängt allerdings stark von den Beleuchtungsverhältnissen ab. Bei Beleuchtung mit einer Punktlichtquelle können einzelne Teilbereiche bei bestimmten Winkeln sehr hell aufblitzen und schnell wieder verschwinden, während in diffusem Umgebungslicht nur ein sehr schwacher oder gegebenenfalls sogar gar kein Beugungseffekt sichtbar sein kann. Auch hängt die wahrgenommene Farbe nicht nur vom Betrachtungswinkel zum Sicherheitselement, sondern auch von der Richtung zur Lichtquelle ab, wobei zudem ein entsprechendes Sicherheitselement zur Betrachtung der Beugungsfarben erster Ordnung nicht direkt vor eine Lichtquelle gehalten werden darf, sondern das Sicherheitselement muss etwas aus der direkten Verbindungslinie heraus gehalten werden. Weiter werden beim Kippen des Sicherheitselements alle Regenbogenfarben durchlaufen, so dass die auftretenden Farbwechsel weitgehend undefiniert sind und die beobachteten Farbeffekte vom ungeschulten Betrachter oft einfach nur als bunt wahrgenommen werden. Schließlich sind holografische Techniken inzwischen auch außerhalb des Sicherheitsbereichs verbreitet und bieten daher nur noch einen begrenzten Nachahmungsschutz.
Bei einer anderen Lösung werden mit Dünnfilmsystemen durch Interferenz im Auflicht und Durchlicht Farben erzeugt, die sich betrachtungswinkelabhängig verändern. Verschiedene Farben werden dabei üblicherweise durch eine Variation der Schichtdicken, beispielsweise der Dicke einer dielektrischen Abstandsschicht in einem Dreischichtaufbau Absorber/Dielektrikum/ Absorber verwirklicht. Die Einstellung einer gewünschten Farbe über die Anpassung der Schichtdicken ist allerdings technologisch sehr aufwendig. Eine Möglichkeit besteht im bereichsweisen Druck einer oder mehrerer dielektrischer Schichten, dabei sind jedoch sehr hohe Anforderungen an die Gleichmäßigkeit der gedruckten Schichten gestellt und die laterale Auflösung ist auf die mit den entsprechenden Druckverfahren erzielbare Auflösung beschränkt. Zudem sind Motivwechsel beim Kippen mit solchen Dünnfilmsystemen praktisch nicht realisierbar.
Eine weitere Lösung besteht darin, mit transparent oder semitransparent beschichteten Subwellenlängenstrukturen im Auf- und Durchlicht Farben zu erzeugen, die sich beim Kippen der Strukturen verändern. Solche Subwellenlängenstrukturen sind allerdings in ihrer Herstellung sehr anspruchsvoll und nur schwer im geforderten großtechnischen Maßstab herzustellen.
Ausgehend davon liegt der Erfindung die Aufgabe zugrunde, ein Durchsichtssicherheitselement der eingangs genannten Art anzugeben, das die Nachteile des Standes der Technik vermeidet. Insbesondere soll das Durchsichtssicherheitselement ein ansprechendes visuelles Erscheinungsbild mit hoher Fälschungssicherheit verbinden und idealerweise in dem im Sicherheitsbereich geforderten großtechnischen Maßstab herstellbar sein.
Diese Aufgabe wird durch die Merkmale der unabhängigen Ansprüche gelöst. Weiterbildungen der Erfindung sind Gegenstand der abhängigen Ansprüche.
Da Neigungswinkel und Azimutwinkel in den genannten Teilbereichen des optisch variablen Flächenmusters jeweils für alle Facetten gleich sind, stellen die Teilbereiche jeweils gerade die Bereiche gleich orientierter Facetten dar.However, conventional transparent or semitransparent security elements with a viewing angle-dependent multicolor color change in transmitted light have various disadvantages. It is known, for example, to produce diffraction colors with translucent or semitransparent coated hologram gratings or transmission gratings in the transmitted light, whereby it can be achieved by suitable choice of the grating periods and the azimuth angle of the grating that different representations with changing colors result under different viewing angles. The appearance of such lattice images, however, strongly depends on the lighting conditions. When illuminated with a point light source, individual subregions can flash very brightly at certain angles and quickly disappear, whereas in diffuse ambient light only a very weak or possibly even no diffraction effect can be visible. Also, the perceived color depends not only on the viewing angle to the security element, but also on the direction to the light source, and also a corresponding security element for viewing the diffraction colors of the first order not directly in front of a light source may be held, but the security element must be kept something out of the direct line of connection. Furthermore, when the security element is tilted, all the rainbow colors are passed through, so that the color changes that occur are largely undefined and the observed color effects are often simply perceived by the untrained viewer as colorful. Finally, holographic techniques are now also used outside the security area and therefore offer only limited protection against counterfeiting.
In another solution, thin-film systems produce colors that change as a function of viewing angle due to interference in reflected light and transmitted light. Different colors are usually realized by a variation of the layer thicknesses, for example the thickness of a dielectric spacer layer in a three-layer structure absorber / dielectric / absorber. The adjustment of a desired color on the adaptation of the layer thicknesses, however, is technologically very expensive. One possibility is to print one or more dielectric layers in sections, but very high demands are placed on the uniformity of the printed layers and the lateral resolution is limited to the resolution achievable with the corresponding printing methods. In addition, motif changes when tilting with such thin film systems are practically unrealizable.
A further solution consists of producing colors with transparent or semitransparently coated subwavelength structures in the transmitted and transmitted light which change when the structures are tilted. However, such subwavelength structures are very demanding in their production and difficult to produce in the required large-scale industrial scale.
Proceeding from this, the present invention seeks to provide a see-through security element of the type mentioned, which avoids the disadvantages of the prior art. In particular, the see-through security element should combine an appealing visual appearance with high security against counterfeiting and ideally be able to be produced in the commercial scale required in the security area.
This object is solved by the features of the independent claims. Further developments of the invention are the subject of the dependent claims.
Since the angle of inclination and the azimuth angle in the mentioned subareas of the optically variable area pattern are the same for all facets in each case, the subareas represent in each case just the areas of similarly oriented facets.
In einer vorteilhaften Ausgestaltung weisen die Facetten eines Teilbereichs nicht nur dieselbe Orientierung, sondern auch dieselbe Form und Größe auf. Die von jedem Teilbereich eingenommene Fläche auf dem optisch variablen Flächenmuster ist in vorteilhaften Ausgestaltungen mindestens 50 mal, bevorzugt mindestens 100 mal, besonders bevorzugt mindestens 1000 mal größer als die von einer einzelnen Facette dieses Flächenbereich im Mittel eingenommen Fläche. Die Teilbereiche enthalten also in der Regel eine sehr große Anzahl einzelner Facetten.In an advantageous embodiment, the facets of a subarea have not only the same orientation but also the same shape and size. The area occupied by each subarea on the optically variable surface pattern is in advantageous embodiments at least 50 times, preferably at least 100 times, more preferably at least 1000 times larger than the area occupied by a single facet of this surface area on average. The sections usually contain a very large number of individual facets.
In einer vorteilhaften Ausgestaltung unterschieden sich die Facetten der zumindest zwei Teilbereiche im Neigungswinkel gegen die Ebene um 5° oder mehr, bevorzugt um 10° oder mehr, besonders bevorzugt um 20° oder mehr. Alternativ oder zusätzlich unterschieden sich die Facetten der zumindest zwei Teilbereiche im Azimutwinkel in der Ebene um 45° oder mehr, bevorzugt um 90° oder mehr, insbesondere um 180°.In an advantageous embodiment, the facets of the at least two partial regions differ in inclination angle against the plane by 5 ° or more, preferably by 10 ° or more, particularly preferably by 20 ° or more. Alternatively or additionally, the facets of the at least two partial regions differ in the azimuth angle in the plane by 45 ° or more, preferably by 90 ° or more, in particular by 180 °.
Die Facetten des Flächenmusters sind bevorzugt durch ebene Flächenstücke gebildet, die jeweils durch ihre Form, Größe und Orientierung charakterisiert sind. Die Orientierung einer Facette wird durch die Neigung α gegen die Ebene des Flächenmusters und durch einen Azimutwinkel θ in der Ebene des Flächenmusters angegeben. Der Azimutwinkel θ ist dabei der Winkel zwischen der Projektion des Normalenvektors der Facette auf die Ebene des Flächenmusters und einer Referenzrichtung in der Ebene. Da der Azimutwinkel θ von der Wahl der Referenzrichtung abhängt, hat sein Absolutwert keine Bedeutung, wohl aber die Differenz der Azimutwinkel verschiedener Teilbereiche, da diese die unterschiedliche relative Orientierung der Facetten in den zugehörigen Teilbereichen beschreibt. Grundsätzlich ist es auch möglich, wenn auch gegenwärtig nicht bevorzugt, gekrümmte Facetten vorzusehen. Auch bei diesen gekrümmten Facetten kann die Orientierung durch einen über ihre Fläche gemittelten Normalenvektor und damit über einen gemittelten Neigungswinkel α und einen gemittelten Azimutwinkel θ angegeben werden.The facets of the surface pattern are preferably formed by flat surface pieces, which are each characterized by their shape, size and orientation. The orientation of a facet is indicated by the inclination α against the plane of the surface pattern and by an azimuth angle θ in the plane of the surface pattern. The azimuth angle θ is the angle between the projection of the normal vector of the facet on the plane of the surface pattern and a reference direction in the plane. Since the azimuth angle θ depends on the choice of the reference direction, its absolute value has no meaning, but the difference of the azimuth angle of different sub-ranges, since this describes the different relative orientation of the facets in the associated sub-areas. In principle, it is also possible, although not currently preferred, to provide curved facets. Even with these curved facets, the orientation can be through a normal vector averaged over its surface and thus an averaged angle of inclination α and an average azimuth angle θ can be specified.
Die Abmessung der Facetten ist vorzugweise so groß, dass keine oder kaum Beugungseffekte auftreten, so dass die Facetten im Wesentlichen nur strahlungsoptisch wirken. Insbesondere weisen die Facetten mit Vorteil eine kleinste Abmessung von mehr als 2 µm, vorzugsweise von mehr als 5 µm, insbesondere von mehr als 10 µm auf. Insbesondere für die Anwendung bei Banknoten und anderen Wertdokumenten weisen die Facetten bevorzugt eine Höhe unterhalb von 100 µm, bevorzugt unterhalb von 50 µm, insbesondere von weniger als 10 µm auf. Die Facetten können regelmäßig, beispielsweise in Form eines 1- oder 2-dimensionalen periodischen Rasters, etwa eines Sägezahngitters, oder auch aperiodisch angeordnet sein.The dimension of the facets is preferably so large that no or hardly diffraction effects occur, so that the facets essentially act only radiation-optical. In particular, the facets advantageously have a smallest dimension of more than 2 μm, preferably more than 5 μm, in particular more than 10 μm. In particular, for use in banknotes and other documents of value, the facets preferably have a height below 100 μm, preferably below 50 μm, in particular below 10 μm. The facets can be arranged regularly, for example in the form of a 1- or 2-dimensional periodic grid, for example a sawtooth grid, or else aperiodically.
Eine weitere Möglichkeit, unerwünschte Beugungseffekte zu unterdrücken, besteht darin, die Facetten in ihrer Höhe über dem Flächenbereich aperiodisch gegeneinander zu versetzen. Bei einer aperiodischen Versetzung der Facetten gibt es keinen einfachen, regelmäßigen Zusammenhang zwischen den Höhen benachbarter Facetten, so dass eine konstruktive Interferenz des an benachbarten Facetten reflektierten Lichts und damit das Entstehen eines überlagerten Beugungsmusters zuverlässig verhindert werden. Einzelheiten einer solchen aperiodischen Versetzung können der Druckschrift
Als Interferenzschicht kommen grundsätzlich alle Beschichtungen in Frage, die im Durchlicht einen betrachtungswinkelabhängigen Farbwechsel zeigen. Ein erstes Beispiel einer vorteilhaften Interferenzschicht ist ein Dünnschichtelement mit semitransparenten Metallschichten und einer dielektrischen Abstandsschicht, insbesondere mit einem Aufbau Absorber/ Dielektrikum/ Absorber, wobei als Absorberschichten beispielsweise Metalle wie Ag, Au, Cr oder Al eingesetzt werden können und als Dielektrikumsschicht SiO2, MgF2 oder Polymere zum Einsatz kommen können. Auch dielektrische Schichtsysteme, insbesondere Multilagensysteme kommen als Interferenzschicht in Betracht, insbesondere Schichtaufbauten mit zumindest einer hochbrechenden Schicht, wie etwa TiO2 oder ZnS, vorzugsweise kombiniert mit zumindest einer niedrigbrechenden Schicht, wie etwa SiO2 oder MgF2. Das Dünnschichtelement kann auch halbleitende Schichten, wie etwa Si enthalten, beispielsweise kann ein Dünnfilmaufbau der Schichtenfolge Si/SiO2/Si verwendet werden. Als dielektrische Abstandsschichten können dabei statt Oxiden beispielsweise auch Polymere eingesetzt werden. Schließlich können auch flüssigkristalline Schichten, insbesondere mit farbwechselnden cholesterischen Flüssigkristallen als Interferenzschicht eingesetzt werden.In principle, all coatings which show a viewing angle-dependent color change in transmitted light can be used as the interference layer. A first example of an advantageous interference layer is a thin-film element with semitransparent metal layers and a dielectric spacer layer, in particular with a structure absorber / dielectric / absorber, wherein for example metals such as Ag, Au, Cr or Al can be used as absorber layers and SiO 2 , MgF 2 or polymers can be used as the dielectric layer. Dielectric layer systems, in particular multilayer systems, are also suitable as interference layer, in particular layer structures with at least one high-index layer, such as TiO 2 or ZnS, preferably combined with at least one low-index layer, such as SiO 2 or MgF 2 . The thin-film element may also contain semiconductive layers, such as Si, for example, a thin-film structure of the Si / SiO 2 / Si layer sequence may be used. As dielectric spacer layers, it is also possible, for example, to use polymers instead of oxides. Finally, it is also possible to use liquid-crystalline layers, in particular with color-changing cholesteric liquid crystals, as the interference layer.
Das gesamte optisch variable Flächenmuster ist vorteilhaft mit derselben Interferenzschicht versehen, die gleichzeitig auf alle Facetten aufgebracht wird. Die Interferenzschicht kann nach dem Aufbringen durch nachfolgende Prozessschritte noch strukturiert werden kann, um interferenzschichtfreie Bereiche zu erzeugen. Auch kann die Interferenzschicht abhängig von der Neigung der Facetten eine lokal unterschiedliche Dicke aufweisen, wie weiter unten genauer erläutert.The entire optically variable surface pattern is advantageously provided with the same interference layer, which is applied simultaneously to all facets. After application, the interference layer can be further structured by subsequent process steps in order to produce interference-layer-free regions. Also, the interference layer depending on the inclination of the facets may have a locally different thickness, as explained in more detail below.
In einer vorteilhaften Ausgestaltung weist die Interferenzschicht eine Schichtdicke auf, die nicht wesentlich von dem Neigungswinkel der beschichteten Facetten abhängt. Eine solche im Wesentlichen konstante Schichtdicke kann beispielsweise mit ungerichteten Beschichtungsverfahren erreicht werden oder ergibt sich bei einer Beschichtung mit cholesterischen Flüssigkristallen in Form konstanter Abstände der Ebenen mit gleichem Brechungsindex.In an advantageous embodiment, the interference layer has a layer thickness which does not depend significantly on the angle of inclination of the coated facets. Such a substantially constant layer thickness can be achieved, for example, with non-directional coating methods be achieved or results in a coating with cholesteric liquid crystals in the form of constant distances of the planes with the same refractive index.
In einer anderen, besonders vorteilhaften Ausgestaltung sind die Facetten mit einer Interferenzschicht versehen, deren Schichtdicke mit dem Neigungswinkel α der Facetten variiert, insbesondere mit zunehmendem Neigungswinkel α abnimmt. Die gegenwärtigen Erfinder haben überraschend gefunden, dass sich durch eine solche Interferenzschicht besonders starke Farbunterschiede zwischen Facetten unterschiedlicher Neigung erzeugen lassen. Dadurch steht einerseits eine besonders große Farbpalette für die farbigen Erscheinungsbilder zu Verfügung, die sogar die Erzeugung von Echtfarbbildern ermöglicht, andererseits können auf diese Weise stark ausgeprägte Farbwechsel beim Kippen der Flächenmuster realisiert werden. Eine derartige variierende Schichtdicke der Interferenzschicht kann beispielsweise mit gerichteten Beschichtungsverfahren, wie etwa Vakuumbedampfungsverfahren erreicht werden. Bei solchen Verfahren führt der Neigungswinkel der Facetten zu einer Vergrößerung der effektiven Oberfläche, so dass auf geneigten Facetten weniger Material pro Flächeneinheit deponiert wird und die resultierende Schichtdicke somit stark vom Neigungswinkel der Facetten abhängt.In another, particularly advantageous embodiment, the facets are provided with an interference layer whose layer thickness varies with the inclination angle α of the facets, in particular decreases with increasing inclination angle α. The present inventors have surprisingly found that such an interference layer can produce particularly strong color differences between facets of different inclinations. As a result, on the one hand, a particularly large color palette for the colored appearances is available, which even allows the production of true color images, on the other hand can be realized in this way strong color change when tilting the surface pattern. Such a varying layer thickness of the interference layer can be achieved, for example, by directional coating methods, such as vacuum evaporation methods. In such processes, the angle of inclination of the facets leads to an increase in the effective surface area, so that less material per unit area is deposited on inclined facets, and the resulting layer thickness thus strongly depends on the angle of inclination of the facets.
Die Facetten sind mit Vorteil in eine Prägelackschicht geprägt, die einen ersten Brechungsindex aufweist. Über der Interferenzschicht ist eine Lackschicht mit einem zweiten Brechungsindex aufgebracht, der sich von dem ersten Brechungsindex der Prägelackschicht um weniger als 0,3 insbesondere um weniger als 0,1 unterscheidet. Durch diesen im Wesentlichen gleichen Brechungsindex der beiden Lackschichten durchquert einfallendes Licht das Sicherheitselement unabhängig vom lokalen Neigungswinkel α der Facetten im Wesentlichen ohne Richtungsablenkung und stellt so eine gleichmäßige Helligkeitsverteilung in der Ebene des Flächenmusters sicher.The facets are advantageously embossed in an embossing lacquer layer having a first refractive index. A lacquer layer having a second refractive index, which differs from the first refractive index of the embossing lacquer layer by less than 0.3, in particular by less than 0.1, is applied over the interference layer. Due to this essentially identical refractive index of the two paint layers, incident light traverses the security element independently of the local inclination angle α of the facets essentially without directional deflection, thus ensuring a uniform distribution of brightness in the plane of the surface pattern.
In einer vorteilhaften Ausgestaltung sind die zumindest zwei Teilbereiche in Form eines Motivs angeordnet, wobei das optisch variable Flächenmuster das von den Teilbereichen gebildete Motiv in Durchsicht zumindest in bestimmten Kippstellungen des Sicherheitselements mit zwei oder mehr verschiedenen Farben zeigt. Dazu sind die Neigungswinkel α und die Azimutwinkel θ der Facetten und die Interferenzschicht in den beiden Teilbereichen mit Vorteil so aufeinander abgestimmt, dass die Teilbereiche in einer bestimmten Kippstellung gleiche Farben und in anderen Kippstellungen unterschiedliche Farben zeigen. Insgesamt zeigt das Sicherheitselement dann ein Motiv, das beim Kippen aus einer homogen erscheinenden Fläche entsteht oder in eine homogen erscheinende Fläche verschwindet.In an advantageous embodiment, the at least two partial regions are arranged in the form of a motif, wherein the optically variable surface pattern shows the motif formed by the partial regions in review, at least in certain tilted positions of the security element with two or more different colors. For this purpose, the inclination angles α and the azimuth angles θ of the facets and the interference layer in the two subregions are advantageously matched to one another in such a way that the subregions display the same colors in a certain tilted position and different colors in other tilted positions. Overall, the security element then shows a motif that arises when tilted from a homogeneous appearing surface or disappears into a seemingly homogeneous surface.
Da die vollständige Farbwirkung der beschichteten Facetten nicht nur von ihrer Orientierung, sondern auch von den Eigenschaften der konkret gewählten Interferenzschicht abhängt, müssen in den Teilbereichen sowohl die Neigungswinkel α der Facetten, die Azimutwinkel θ der Facetten und die Interferenzschicht so aufeinander abgestimmt sein, dass die gewünschte Farbwirkung erreicht wird.Since the complete color effect of the coated facets depends not only on their orientation, but also on the properties of the interference layer selected, both the inclination angles α of the facets, the azimuth angles θ of the facets and the interference layer must be coordinated in the subregions such that the desired color effect is achieved.
Bei einer vorteilhaften Weiterbildung enthält das optisch variable Flächenmuster zumindest drei Teilbereiche, die in Form eines Hintergrundbereichs und von zwei Vordergrundbereichen angeordnet sind, und in denen die Neigungswinkel α und die Azimutwinkel θ der Facetten und die Interferenzschicht so aufeinander abgestimmt sind, dass das optisch variable Flächenmuster in Durchsicht
- in einer ersten Kippstellung ein erstes Motiv zeigt, bei dem der erste Vordergrundbereich mit einer Motivfarbe und der zweite Vordergrundbereich und der Hintergrundbereich mit einer von der Motivfarbe unterschiedlichen Hintergrundfarbe erscheinen, und
- in einer zweiten Kippstellung ein zweites Motiv zeigt, bei dem der zweite Vordergrundbereich mit der Motivfarbe und der erste Vordergrundbereich und der Hintergrundbereich mit der Hintergrundfarbe erscheinen.
- in a first tilted position shows a first motif, in which the first foreground area with a subject color and the second foreground area and the background area appear with a different background color of the subject color, and
- in a second tilt position, a second motif is shown, in which the second foreground area with the subject color and the first foreground area and the background area with the background color appear.
Mit Vorteil enthält das optisch variable Flächenmuster in einer Weiterbildung zumindest vier Teilbereiche, die in Form eines Hintergrundbereichs, von zwei Vordergrundbereichen und eines Überlappungsbereichs angeordnet sind, und in denen die Neigungswinkel α und die Azimutwinkel θ der Facetten und die Interferenzschicht so aufeinander abgestimmt sind, dass das optisch variable Flächenmuster in Durchsicht
- in einer ersten Kippstellung ein erstes Motiv zeigt, bei dem der erste Vordergrundbereich und der Überlappungsbereich mit einer Motivfarbe und der zweite Vordergrundbereich und der Hintergrundbereich mit einer von der Motivfarbe unterschiedlichen Hintergrundfarbe erscheinen, und
- in einer zweiten Kippstellung ein zweites Motiv zeigt, bei dem der zweite Vordergrundbereich und der Überlappungsbereich mit der Motivfarbe und der erste Vordergrundbereich und der Hintergrundbereich mit der Hintergrundfarbe erscheinen.
- in a first tilted position, showing a first motif in which the first foreground area and the overlapping area with a subject color and the second foreground area and the background area with a background color different from the subject color appear, and
- in a second tilt position, a second motif is shown, where the second foreground area and the overlap area with the subject color and the first foreground area and the background area with the background color appear.
In allen Gestaltungen enthält das optisch variable Flächenmuster mit Vorteil zumindest zwei Teilbereiche, in denen die Facetten den gleichen Neigungswinkel a, aber sich um 180° unterscheidende Azimutwinkel θ aufweisen. Die Neigungswinkel α sind dabei mit Vorteil größer als 5°, besonders bevorzugt größer als 10°, und betragen beispielsweise 15°, 20° oder 25°. Wie weiter unten genauer erläutert, kann auf diese Weise ein Kippbild mit einem aus einer homogenen Fläche herauskippendem oder in eine homogene Fläche hineinkippendem Motiv realisiert werden.In all configurations, the optically variable surface pattern advantageously contains at least two partial regions in which the facets have the same inclination angle a but azimuth angles θ differing by 180 °. The inclination angles α are advantageously greater than 5 °, particularly preferably greater than 10 °, and are for example 15 °, 20 ° or 25 °. As explained in more detail below, in this way, a tilt image with one of a homogeneous surface herauskippendem or eininkippendem in a homogeneous surface motif can be realized.
Enthält das optisch variable Flächenmuster zumindest vier Teilbereiche, so ist mit Vorteil vorgesehen, dass das optisch variable Flächenmuster einen ersten und zweiten Teilbereich enthält, in denen die Facetten den gleichen Neigungswinkel ao, aber sich um 180° unterscheidende Azimutwinkel θ aufweisen, und weiter einen dritten und vierten Teilbereich enthält, in denen die Facetten unterschiedliche Neigungswinkel α1 bzw. α2 aufweisen und in denen sich der Azimutwinkel θ um 90° oder 270° von dem Azimutwinkel des ersten und zweiten Teilbereichs unterscheidet. Die Neigungswinkel α0 sind dabei mit Vorteil größer als 5°, besonders bevorzugt größer als 10°, und betragen beispielsweise 15°, 20° oder 25°. Wie weiter unten genauer erläutert, kann auf diese Weise in besonders einfacher Weise ein Kippbild mit zwei unterschiedlichen Motiven realisiert werden.If the optically variable surface pattern contains at least four partial regions, it is advantageously provided that the optically variable surface pattern contains a first and second partial region in which the facets have the same inclination angle ao but azimuth angles θ differing by 180 °, and further a third and fourth sub-area, in which the facets have different inclination angles α 1 and α 2 and in which the azimuth angle θ differs by 90 ° or 270 ° from the azimuth angle of the first and second sub-area. The inclination angles α 0 are advantageously greater than 5 °, particularly preferably greater than 10 °, and are for example 15 °, 20 ° or 25 °. As explained in more detail below, can be realized in this way in a particularly simple manner, a tilt image with two different motifs.
Grundsätzlich können Kippbilder mit zwei unterschiedlichen, auch überlappenden Motiven bereits mit einem optisch variablen Flächenmuster mit nur drei Teilbereichen realisiert werden. Im Fall zumindest teilweise überlappender Motive erfordert dies allerdings in der Regel eine Verschachtelung der den Motiven zugeordneten Teilbereiche, bei der, wie weiter unten genauer beschrieben, das Flächenmuster in schmale Streifen oder kleine Pixel zerlegt wird.In principle, tilt images with two different, even overlapping motifs can already be realized with an optically variable surface pattern with only three partial areas. In the case of at least partially overlapping motifs, however, this usually requires an interleaving of the subregions assigned to the motifs, in which, as described in more detail below, the surface pattern is decomposed into narrow strips or small pixels.
In einer vorteilhaften Weiterbildung enthält das optisch variable Flächenmuster zumindest drei Teilbereiche, in denen die Neigungswinkel α und die Azimutwinkel θ der Facetten und die Interferenzschicht so aufeinander abgestimmt sind, dass die Teilbereiche in einer Kippstellung in Durchsicht Rot, Grün, bzw. Blau erscheinen. Vorzugsweise werden diese Farben bei unverkipptem Sicherheitselement, also bei senkrechter Durchsichtsbetrachtung erzeugt. In einer vorteilhaften Weiterbildung kann das optisch variable Flächenmuster dabei in den Teilbereichen zusätzlich eine zu den geneigten Facetten gepasserte Schwarzmaske aufweisen, die der Einstellung der Durchsichtshelligkeit der Facetten in den jeweiligen Teilbereichen dient. Die drei Teilbereiche können, gegebenenfalls zusammen mit der gepasserten Schwarzmaske, dabei mit Vorteil jeweils die Farbauszüge eines Echtfarbbilds darstellen. Auf diese Weise lassen sich in der ausgewählten Kippstellung in Durchsicht realistisch erscheinende Echtfarbbilder darstellen.In an advantageous development, the optically variable surface pattern contains at least three subregions in which the inclination angle α and the azimuth angle θ of the facets and the interference layer are matched to one another so that the subregions appear in a tilted position as viewed in red, green or blue. Preferably, these colors are not tipped Security element, that is generated in vertical viewing. In an advantageous development, the optically variable surface pattern may additionally have in the subregions a black mask which has been matched to the inclined facets and which serves to adjust the translucent brightness of the facets in the respective subregions. The three subareas may, optionally together with the black mask, thereby advantageously represent the color separations of a true color image. In this way can be displayed in the selected tilt position in perspective realistic appearing true color images.
Die Erfindung enthält auch einen Datenträger mit einem Durchsichtssicherheitselement der beschriebenen Art, wobei das Durchsichtssicherheitselement vorzugsweise in oder über einem Fensterbereich oder einer durchgehenden Öffnung des Datenträgers angeordnet ist. Bei dem Datenträger kann es sich insbesondere um ein Wertdokument, wie eine Banknote, insbesondere eine Papierbanknote, eine Polymerbanknote oder eine Folienverbundbanknote handeln, aber auch um eine Ausweiskarte, wie etwa eine Kreditkarte, eine Bankkarte, eine Barzahlungskarte, eine Berechtigungskarte, einen Personalausweis oder eine Passpersonalisierungsseite handeln.The invention also includes a data carrier with a see-through security element of the type described, wherein the see-through security element is preferably arranged in or over a window region or a through opening of the data carrier. The data carrier may in particular be a value document, such as a banknote, in particular a paper banknote, a polymer banknote or a film composite banknote, but also an identity card, such as a credit card, bank card, cash card, authorization card, identity card or a Trade personalization page.
Die Erfindung enthält weiter ein Verfahren zum Herstellen eines optisch variablen Durchsichtssicherheitselements, bei dem ein Substrat bereitgestellt wird und das Substrat mit einem ebenen, optisch variablen Flächenmuster versehen wird, das in Durchsicht ein farbiges Erscheinungsbild mit einem betrachtungswinkelabhängigen mehrfarbigen Farbwechsel zeigt. Erfindungsgemäß wird dabei das optisch variable Flächenmuster mit einer Vielzahl von im Wesentlichen strahlungsoptisch wirkenden Facetten erzeugt wird, deren Orientierung jeweils durch einen Neigungswinkel α gegen die Ebene des Flächenmusters, der zwischen 0° und 45° liegt, und durch einen Azimutwinkel θ in der Ebene des Flächenmusters charakterisiert ist, werden die Facetten mit einer Interferenzschicht mit einem im Durchlicht betrachtungswinkelabhängigen Farbwechsel versehen, und wird das optisch variable Flächenmuster mit zumindest zwei Teilbereichen mit jeweils einer Vielzahl gleich orientierter Facetten erzeugt, wobei sich die Facetten der zumindest zwei Teilbereiche voneinander im Neigungswinkel gegen die Ebene und/oder im Azimutwinkel in der Ebene unterscheiden.The invention further includes a method of fabricating an optically variable see-through security element in which a substrate is provided and the substrate is provided with a planar, optically variable area pattern which shows in phantom a colored appearance with a viewing angle dependent multicolor color change. According to the invention, the optically variable surface pattern is generated with a plurality of substantially radiation-optical facets whose orientation is in each case by an inclination angle α against the plane of the surface pattern, which lies between 0 ° and 45 °, and by a Azimuth angle θ is characterized in the plane of the surface pattern, the facets are provided with an interference layer with a viewing angle-dependent color change, and the optically variable surface pattern is generated with at least two subregions, each having a plurality of identically oriented facets, wherein the facets of the at least two Divide sections from each other in the angle of inclination against the plane and / or in the azimuth angle in the plane.
In einer vorteilhaften Verfahrensvariante werden die Facetten in einem gerichteten Beschichtungsverfahren, insbesondere in einem Vakuumbedampfungsverfahren mit der Interferenzschicht beschichtet.In an advantageous variant of the method, the facets are coated with the interference layer in a directional coating process, in particular in a vacuum vapor deposition process.
Weitere Ausführungsbeispiele sowie Vorteile der Erfindung werden nachfolgend anhand der Figuren erläutert, bei deren Darstellung auf eine maßstabs- und proportionsgetreue Wiedergabe verzichtet wurde, um die Anschaulichkeit zu erhöhen.Further exemplary embodiments and advantages of the invention are explained below with reference to the figures, in the representation of which a representation true to scale and proportion has been dispensed with in order to increase the clarity.
Es zeigen:
- Fig. 1
- eine schematische Darstellung einer Banknote mit einem erfindungsgemäßen optisch variablen Durchsichtsicherheitselement,
- Fig. 2
- schematisch den Schichtaufbau des Sicherheitselements der
Fig. 1 im Querschnitt, - Fig. 3
- schematisch ein berechnetes Farbspektrum von Facetten mit einer dreischichtigen Interferenzbeschichtung mit einer ersten, 25 nm dicken Ag-Schicht, einer SiO2-Abstandsschicht der Dicke d und einer zweiten, ebenfalls 25 nm dicken Ag-Schicht, aufgetragen in Abhängigkeit von der Dicke d und dem Winkel φ des Lichteinfalls auf die Interferenzbeschichtung,
- Fig. 4
- zur Erläuterung des auftretenden Kippeffekts das Sicherheitselement der
Fig. 2 mit der Interferenzbeschichtung derFig. 3 , in (a) in nicht verkippter Lage und in (b) in einer um β = 20° nach rechts gekippten Lage, - Fig. 5
- ein Sicherheitselement nach einem weiteren Ausführungsbeispiel der Erfindung, bei dem in unterschiedlichen Kippstellungen unterschiedliche Motive sichtbar sind, wobei (a) in Aufsicht die Aufteilung des optisch variablen Flächenmusters des Sicherheitselements in drei Teilbereiche zeigt, und (b) bis (d) das Sicherheitselement im Querschnitt in verschiedenen Kippstellungen zeigen,
- Fig. 6
- ein Sicherheitselement nach einem weiteren Ausführungsbeispiel der Erfindung, dessen optisch variables Flächenmuster in vier Teilbereiche aufgeteilt ist,
- Fig. 7
- schematisch ein berechnetes Farbspektrum von beschichteten Facetten bei senkrechtem Lichteinfall auf die Ebene des Flächenmusters, wobei die Interferenzbeschichtung durch eine dreischichtige Interferenzbeschichtung mit einer ersten, 25 nm dicken Ag-Schicht, einer SiO2-Abstandsschicht der nominellen Dicke d0 und einer zweiten, ebenfalls 25 nm dicken Ag-Schicht gebildet ist, und die Schichtdicke d der Abstandsschicht mit dem Neigungswinkel α gemäß der Beziehung d = d0 cos α abnimmt, wobei das Farbspektrum in Abhängigkeit von der nominellen Dicke d0 der Abstandsschicht und dem Neigungswinkel α der Facetten aufgetragen ist, und
- Fig. 8
- in (a) bis (e) im Querschnitt verschiedene Zwischenstadien bei der Herstellung eines optisch variablen Flächenmusters zur Darstellung eines Echtfarbbilds mit einer passergenauen Schwarzmaske.
- Fig. 1
- a schematic representation of a banknote with an optically variable transparent security element according to the invention,
- Fig. 2
- schematically the layer structure of the security element of
Fig. 1 in cross section, - Fig. 3
- schematically a calculated color spectrum of facets with a three-layer interference coating with a first, 25 nm thick Ag layer, a SiO 2 spacer layer of thickness d and a second, likewise 25 nm thick Ag layer, applied as a function of the thickness d and the angle φ of the light incident on the interference coating,
- Fig. 4
- to explain the occurring tilting the security element of
Fig. 2 with the interference coating ofFig. 3 , in (a) in a non-tilted position and in (b) in a position tilted β = 20 ° to the right, - Fig. 5
- a security element according to a further embodiment of the invention, in which different motifs are visible in different tilt positions, wherein (a) shows in plan the division of the optically variable surface pattern of the security element into three sections, and (b) to (d) the security element in cross section show in different tilt positions,
- Fig. 6
- a security element according to a further exemplary embodiment of the invention, whose optically variable area pattern is divided into four partial areas,
- Fig. 7
- schematically a calculated color spectrum of coated facets at normal incidence of light on the plane of the surface pattern, wherein the interference coating by a three-layer interference coating with a first, 25 nm thick Ag layer, a SiO 2 spacer layer of nominal thickness d 0 and a second, also 25 nm thick Ag layer is formed, and the layer thickness d of the spacer layer decreases with the inclination angle α according to the relationship d = d 0 cos α, wherein the color spectrum is plotted against the nominal thickness d 0 of the spacer layer and the inclination angle α of the facets, and
- Fig. 8
- in (a) to (e) in cross-section different intermediate stages in the production of an optically variable surface pattern to represent a true color image with a register-accurate black mask.
Die Erfindung wird nun am Beispiel von Sicherheitselementen für Banknoten erläutert.
Bei dem Ausführungsbeispiel der
Das Sicherheitselement 12 weist ein ebenes, optisch variables Flächenmuster auf, das eine Vielzahl von im Wesentlichen strahlungsoptisch wirkenden Facetten 32 enthält. Die Facetten 32 sind durch ebene Flächenstücke gebildet und sind jeweils durch ihre Form, Größe und Orientierung charakterisiert. Wie oben bereits allgemein erläutert, wird die Orientierung einer Facette 32 durch die Neigung α zur Ebene 30 des Flächenbereichs und durch einen Azimutwinkel θ in der Ebene 30 angegeben, wobei der Azimutwinkel θ der Winkel zwischen der Projektion des Normalenvektors 46, 48 einer Facette 32 auf die Ebene 30 und einer Referenzrichtung Ref ist.The
Wie in
Die Facetten 32 des Flächenmusters sind in einen vorzugsweise transparenten Prägelack 34 eingeprägt und weisen im Ausführungsbeispiel einen quadratischen Umriss mit einer Abmessung von 20 µm x 20 µm auf. Die Facetten 32 sind weiter mit einer nahezu transparenten oder zumindest semitransparenten Interferenzbeschichtung 36 versehen, die in Durchsicht einen vom Betrachtungswinkel abhängigen Farbeindruck erzeugt.The
Die Interferenzbeschichtung 36 kann beispielsweise aus einem Dreischicht-Dünnfilmaufbau mit zwei metallischen semitransparenten Schichten, etwa aus Aluminium, Silber, Chrom, Gold oder Kupfer und einer dazwischen liegenden dielektrischen Abstandsschicht, etwa aus SiO2, MgF2 oder einem Polymer gebildet sein. Bei den zunächst beschriebenen Ausführungsbeispielen ist die Dicke der Interferenzbeschichtung 36 unabhängig von dem Neigungswinkel α der Facetten 32.The
Über der Interferenzbeschichtung 36 ist eine weitere Lackschicht 38 aufgebracht, die im Wesentlichen denselben Brechungsindex wie die Lackschicht 34 aufweist, was sicherstellt, dass einfallendes Licht die Schichtenfolge des Sicherheitselements 12 unabhängig vom lokalen Neigungswinkel α der Facetten 32 im Wesentlichen ohne Richtungsablenkung durchquert und so eine gleichmäßige Helligkeitsverteilung in der Ebene des Flächenmusters erzeugt.Over the
Die Interferenzbeschichtung 36 der Facetten erzeugt im Durchlicht einen Farbeindruck, der sowohl von der Einfallsrichtung des Lichts relativ zur Ebenennormale des optisch variablen Flächenmusters als auch vom individuellen Neigungswinkel der Facetten 32 abhängt, da beide Faktoren den Einfallswinkel des Lichts bezogen auf die Normale der Interferenzbeschichtung 36 beeinflussen.The
Verwendet man bei dem Ausführungsbeispiel der
In
Im Teilbereich 16 wird durch die Verkippung nach rechts der Winkel zwischen dem einfallenden Licht 40 und der Interferenzschichtnormale 46 um β = 20° vermindert, so dass das Licht 40 dort nunmehr senkrecht auf die Interferenzschicht 36 einfällt (φ = 0°). Wie der
Bei einer Verkippung um 20° nach links kehren sich die Verhältnisse entsprechend um, so dass dann das Licht 40 im Teilbereich 18 senkrecht auf die Interferenzschicht 36 einfällt und dort eine rote Durchsichtsfarbe erzeugt, während es im Teilbereich 16 unter einem Winkel von φ = 40° auf die Interferenzschicht 36 einfällt und eine grüne Durchsichtsfarbe erzeugt.With a tilt by 20 ° to the left, the conditions are reversed accordingly, so that then the light 40 in the
Der einfarbige homogene Farbeindruck bei senkrechtem Lichteinfall in
Ein erfindungsgemäßes Sicherheitselement 60 kann auch ein Kippbild zeigen, bei dem in unterschiedlichen Kippstellungen unterschiedliche Motive sichtbar sind, wie nunmehr mit Bezug auf
Die Interferenzschicht 36 ist in diesem Ausführungsbeispiel so gewählt, dass sie bei senkrechtem Lichteinfall (φ = 0°) eine orange Durchsichtsfarbe erzeugt, bei Lichteinfall unter φ = 10° eine gelbe Durchsichtsfarbe, bei Lichteinfall unter φ = 20° eine grüne Durchsichtsfarbe und bei Lichteinfall unter φ = 30° eine blaue Durchsichtsfarbe.In this exemplary embodiment, the
In der nicht verkippten Lage der
In der Lage der
Umgekehrt ist in der Lage der
Bei den Ausführungsbeispielen der
Bei dem Ausführungsbeispiel der
Die Verschachtelung von überlappenden Darstellungen mit drei Teilbereichen mit unterschiedlichen Facettenorientierungen führt allerdings in der Regel dazu, dass die Buntheit bzw. der Kontrast der Durchsichtsfarben nicht die maximal möglichen Werte erreicht, da durch die Verschachtelung teilweise nur Mischfarben erzeugt werden können, und Mischfarben in der Regel eine geringer Buntheit als die Ausgangsfarben aufweisen.However, the interleaving of overlapping representations with three subregions with different facet orientations usually leads to the fact that the chroma or the contrast of the see-through colors does not reach the maximum possible values, since the interleaving can in part only produce mixed colors, and mixed colors in general have a lower chroma than the original colors.
Sehr kontrastreiche und bunte Kippbilder lassen sich allerdings durch die Verwendung von vier Teilbereichen mit unterschiedlichen Facettenorientierungen verwirklichen, wie in
Bei dem Sicherheitselement 80 ist das optisch variable Flächenmuster in vier Teilbereiche 82, 84, 86, 88 aufgeteilt, die in Form eines Hintergrundbereichs 82, eines ersten Vordergrundbereichs 84 (Quadrat ohne Kreissegment 88), eines zweiten Vordergrundbereichs 86 (Kreisscheibe ohne Kreissegment 88) und eines Überlappungsbereichs 88 (Kreissegment) angeordnet sind. Der erste Vordergrundbereich 84 bildet dabei zusammen mit dem Kreissegment 88 als erstes darzustellendes Motiv das vollständige Quadrat, der zweite Vordergrundbereich 86 bildet zusammen mit dem Kreissegment 88 als zweites darzustellendes Motiv die vollständige Kreisscheibe. Obwohl die beiden darzustellenden Motive im Überlappungsbereich 88 überlappen, soll ihre Durchsichtsfarbe nicht durch Farbmischung entstehen.In the
Die Neigungen und Azimutwinkel der Facetten in den vier Teilbereichen sind dazu so gewählt, dass das Sicherheitselement 80 in einer ersten Kippstellung im Durchlicht als erstes darzustellendes Motiv das vollständige Quadrat (erste Vordergrundbereich 84 und Kreissegment 88 zusammen) mit einer einheitlichen Motivfarbe und das restlichen Flächenmuster (zweite Vordergrundbereich 86 und Hintergrundbereich 82) mit einer von der Motivfarbe unterschiedlichen Hintergrundfarbe zeigt. In einer zweiten Kippstellung zeigt das Sicherheitselement 80 im Durchlicht als zweites darzustellendes Motiv den vollständigen Kreis (zweiter Vordergrundbereich 86 und Kreissegment 88 zusammen) mit der einheitlichen Motivfarbe, während das restliche Flächenmuster (erster Vordergrundbereich 84 und Hintergrundbereich 82) mit der Hintergrundfarbe erscheint.The inclinations and azimuth angles of the facets in the four subregions are selected so that the
Um dies zu erreichen sind die Neigung und der Azimutwinkel der Facetten im Hintergrundbereich 82 also so gewählt, dass sie sowohl in der ersten als auch in der zweiten Kippstellung jeweils die Hintergrundfarbe erzeugen. Die Neigung und der Azimutwinkel der Facetten im ersten Vordergrundbereich 84 sind so gewählt, dass sie in der ersten Kippstellung die Motivfarbe und in der zweiten Kippstellung die Hintergrundfarbe erzeugen, während die Facetten im zweiten Vordergrundbereich 86 so gewählt sind, dass sie in der ersten Kippstellung die Hintergrundfarbe und in der zweiten Kippstellung die Motivfarbe erzeugen. Im Überlappungsbereich 88 schließlich sind Neigung und Azimutwinkel der Facetten so gewählt, dass sie sowohl in der ersten wie in der zweiten Kippstellung jeweils die Motivfarbe erzeugen. Insgesamt werden also vier Teilbereiche mit unterschiedlichen Orientierungen der Facetten benötigt.In order to achieve this, the inclination and the azimuth angle of the facets in the
Die erforderlichen Neigungen und Azimutwinkel in den verschiedenen Teilbereichen können beispielsweise durch folgende Vorgehensweise ermittelt werden, wobei konkret angenommen wird, dass die erste Kippstellung durch eine Verkippung 90-0 des Sicherheitselements 80 um einen bestimmten Winkel aus der Waagrechten nach oben entsteht, während die zweite Kippstellung durch eine Verkippung 90-U des Sicherheitselements 80 um denselben Winkel nach unten entsteht.The required inclinations and azimuth angles in the various subregions can be determined, for example, by the following procedure, wherein it is concretely assumed that the first tilted position results from a tilting 90-0 of the
Zunächst wird für die Facetten des ersten und zweiten Vordergrundbereichs 84, 86 der Azimutwinkel in Verkippungsrichtung 90-0, 90-U, also auf θ = 270° bzw. θ = 90° bezogen auf die in der Figur gezeigte Referenzrichtung Ref festgelegt. Als Neigungswinkel α wird für beide Vordergrundbereiche derjenige Winkel festgelegt, der bei einer Neigung der Spiegel nach oben bzw. unten in der ersten bzw. zweiten Kippstellung die gewünschte Motivfarbe erzeugt. Dies entspricht im Wesentlichen dem bereits im Zusammenhang mit
Ähnlich wie bei
Weiter wurde im Rahmen einer Versuchsreihe ermittelt, bei welchen Neigungswinkeln die mit der gewählten Interferenzbeschichtung beschichteten Facetten bei einem Azimutwinkel von 0° oder 180° in der ersten Kippstellung die Motivfarbe bzw. die Hintergrundfarbe zeigen. Diese Neigungswinkel hängen im Allgemeinen von der Art der Interferenzbeschichtung, der Abhängigkeit der Interferenzschichtdicke vom Neigungswinkel der Facetten und den Brechungsindizes der einbettenden Lackschichten ab, können aber problemlos durch eine einfache Versuchsreihe ermittelt werden. Beispielsweise ergibt sich, dass die Facetten in der ersten Kippstellung bei einem Azimutwinkel von 0° und einem Neigungswinkel αM die Motivfarbe zeigen und bei einem Neigungswinkel αH die Hintergrundfarbe zeigen. Wegen der Symmetrie der Anordnung ist dann sichergestellt, dass die Facetten diese Farben auch in der zweiten Kippstellung zeigen, da diese durch eine Verkippung des Sicherheitselements um denselben Winkelbetrag wie die erste Kippstellung erreicht wird.It was also determined in a series of experiments at which angles of inclination coated with the selected interference coating facets at an azimuth angle of 0 ° or 180 ° in the first tilt position, the subject color or the background color. These angles of inclination generally depend on the type of interference coating, the dependence of the interference layer thickness on the angle of inclination of the facets and the refractive indices of the embedding lacquer layers, but can easily be determined by a simple series of experiments. For example, it follows that the facets in the first tilt position at an azimuth angle of 0 ° and an inclination angle α M show the subject color and at an inclination angle α H show the background color. Because of the symmetry of the arrangement is then ensured that the facets this Show colors even in the second tilted position, as this is achieved by tilting the security element by the same angular amount as the first tilted position.
Die Facetten im Überlappungsbereich 88 werden dann mit einem Neigungswinkel α = αM und einem Azimutwinkel von θ = 0° oder θ = 180° gebildet, während die Facetten im Hintergrundbereich 82 mit einem Neigungswinkel α = αH und einem Azimutwinkel von θ = 0° oder θ = 180° gebildet werden. Die zugehörigen projizierten Normalenvektoren 98 bzw. 92 sind für θ = 0° in
Bei den bisher beschriebenen Ausführungsbeispielen war die Dicke der Interferenzbeschichtung unabhängig von dem Neigungswinkel der Facetten. Besonders starke Farbunterschiede lassen sich allerdings erzeugen, wenn zum Aufbringen der Interferenzbeschichtung ein Beschichtungsverfahren gewählt wird, bei dem die erzielte Schichtdicke von der Neigung der Facetten abhängt. Dies kann beispielsweise durch eine gerichtete Vakuumbedampfung der Facetten erreicht werden, wobei sich bei senkrechter Bedampfung eine Schichtdicke ergibt, die im Wesentlichen proportional zum Cosinus des Neigungswinkels α ist, also
Wie ein Vergleich der
Die oben beschriebenen Ausführungsbeispiele lassen sich nicht nur mit Interferenzbeschichtung konstanter Dicke, sondern vorteilhaft auch mit einer Interferenzbeschichtung mit neigungsabhängiger Dicke verwirklichen, wodurch beispielsweise Kippbilder mit besonders starken Farbkontrasten erzeugt werden können.The embodiments described above can be realized not only with interference coating constant thickness, but advantageously also with an interference coating with tilt-dependent thickness, which can be generated, for example, tilt images with particularly strong color contrasts.
Besonders bemerkenswert und überraschend ist dabei, dass es bei manchen Interferenzschichtsystemen bestimmte Schichtdicken gibt, bei denen mit ein und derselben Interferenzbeschichtung je nach Neigungswinkel der Facetten als Durchsichtsfarben die Grundfarben Rot, Grün und Blau erzeugt werden können. Im in
Auf diese Weise lassen sich durch geeignete Anordnung von kleinen roten, grünen und blauen Farbbereichen in Durchsicht Echtfarbbilder erzeugen, da jede beliebige Farbe als additive Farbmischung dieser drei Grundfarben dargestellt werden kann. Die Teilbereiche werden dazu beispielsweise wie bei einem herkömmlichen RGB-Display in Form kleiner Pixel oder Streifen ausgebildet.In this way, by suitable arrangement of small red, green and blue color areas in view true color images can be generated because any color can be represented as additive color mixing of these three primary colors. The subregions are formed for this purpose, for example, as in a conventional RGB display in the form of small pixels or stripes.
Um realistische Echtfarbbilder erzeugen zu können, muss noch die Helligkeit der Farbbereiche in den einzelnen Pixeln gezielt eingestellt werden können. Die Farbbereiche einzelner Pixel können dazu beispielsweise schwarz überdruckt oder mit einer opaken Metallisierung überzogen werden, wobei die technologische Herausforderung in der passergenauen Anordnung der Überdruckung oder des Überzugs besteht.In order to be able to produce realistic true color images, the brightness of the color areas in the individual pixels must be able to be specifically adjusted. For example, the color areas of individual pixels can be overprinted black or coated with an opaque metallization, the technological challenge being the exact registration of overprinting or of the coating.
Konkret kann ein optisch variables Flächenmuster zur Darstellung eines Echtfarbbilds mit einer passergenauen Schwarzmaske in der mit Bezug auf
Mit Bezug auf
Anschließend wird die geprägte Lackschicht 34, wie in
Dann wird, wie in
Nun wird auf die gegenüberliegende Seite des Flächenmusters ein geschwärzter Fotolack 118 aufgebracht, wie in
Bei einer anderen Verfahrensvariante kann im Schritt der
Grundsätzlich kann die Schwarzmaske allerdings auch durch andere Verfahren erzeugt werden, beispielsweise durch Metalltransferverfahren, Ätzverfahren oder auch direkt oder indirekt über durch geprägte Strukturen gesteuerte Laserablation.In principle, however, the black mask can also be produced by other methods, for example by metal transfer methods, etching methods or else directly or indirectly via laser ablation controlled by embossed structures.
- 1010
- Banknotebill
- 1212
- DurchsichtssicherheitselementThrough security element
- 1414
- durchgehende Öffnungthrough opening
- 1616
- Vordergrundforeground
- 1818
- Hintergrundbackground
- 20-R, 20-L20-R, 20-L
- Kipprichtungentilt directions
- 3030
- Ebene des FlächenbereichsPlane of the surface area
- 3232
- Facettenfacets
- 3434
- Prägelackembossing lacquer
- 3636
- Interferenzbeschichtunginterference coating
- 3838
- Lackschichtpaint layer
- 4040
- einfallendes Lichtincident light
- 4242
- Ebenennormaleplane normal
- 46, 4846, 48
- InterferenzschichtnormaleInterference layer normal
- 50, 52, 5450, 52, 54
-
Punkte in
Fig. 3 Points inFig. 3 - 6060
- Sicherheitselementsecurity element
- 62, 64, 6662, 64, 66
- Teilbereichesubregions
- 72, 74, 7672, 74, 76
- InterferenzschichtnormaleInterference layer normal
- 8080
- Sicherheitselementsecurity element
- 82, 84, 86, 8882, 84, 86, 88
- Teilbereichesubregions
- 90-O, 90-U90-O, 90-U
- Kipprichtungentilt directions
- 92, 94, 96, 9892, 94, 96, 98
- projizierte Normalenvektorenprojected normal vectors
- 100, 102, 104100, 102, 104
-
Punkte in
Fig. 7 Points inFig. 7 - 110110
- optisch variables Flächenmusteroptically variable surface pattern
- 112112
- Farbpixelcolor pixels
- 114-R, 114-G, 114-B114-R, 114-G, 114-B
- Farbbereichecolor ranges
- 116116
- Erhöhungenincreases
- 118118
- Fotolackphotoresist
- 120120
- Belichtungexposure
- 122122
- SchwarzmaskeBlack mask
- RefRef
- Referenzrichtungreference direction
Claims (15)
- An optically variable see-through security element (12) for securing objects of value (10) with a planar, optically variable area pattern (16, 18),
wherein the optically variable area pattern includes a multiplicity of facets (32) which have a substantially ray-optical effect and the orientation of which is distinguished respectively by an inclination angle α relative to the plane (30) of the area pattern, and by an azimuth angle θ in the plane of the area pattern,
wherein the optically variable area pattern includes at least two subregions (16, 18) respectively having a multiplicity of identically oriented facets, wherein the facets of the at least two subregions differ from each other with respect to the inclination angle relative to the plane and/or the azimuth angle in the plane,
the inclination angle α is between 0° and 45°,
characterized in that
the facets of the at least two subregions are supplied with an interference layer (36), the interference layer has a viewing-angle-dependent color change in transmitted light, and
the optically variable area pattern shows a colored appearance with a viewing-angle-dependent, polychrome color change in transmission. - The see-through security element according to claim 1, characterized in that the area occupied by each subregion on the optically variable area pattern is at least 50 times, preferably at least 100 times, particularly preferably at least 1000 times greater than the area occupied on average by one individual facet of this area region.
- The see-through security element according to claim 1 or 2, characterized in that the facets of the at least two subregions differ with respect to the inclination angle relative to the plane by 5° or more, preferably by 10° or more, particularly preferably by 20° or more, and/or that the facets of the at least two subregions differ with respect to the azimuth angle in the plane by 45° or more, preferably by 90° or more, in particular by 180°.
- The see-through security element according to at least one of claims 1 to 3, characterized in that the facets are each supplied with an interference layer the thickness of which varies with the inclination angle α of the facets, preferably decreases with an increasing inclination angle α.
- The see-through security element according to at least one of claims 1 to 4, characterized in that the at least two subregions are arranged in the form of a motif, so that the optically variable area pattern shows the motif formed by the subregions with two or more different colors in transmission at least in certain tilted positions of the security element.
- The see-through security element according to at least one of claims 1 to 5, characterized in that the inclination angles α and the azimuth angles θ of the facets and the interference layer are mutually coordinated in the subregions such that the subregions show the same colors in one certain tilted position and different colors in other tilted positions.
- The see-through security element according to at least one of claims 1 to 6, characterized in that the optically variable area pattern includes at least three subregions which are arranged in the form of a background region and of two foreground regions and in which the inclination angles α and the azimuth angles θ of the facets and the interference layer are so mutually coordinated that the optically variable area pattern in transmission- in a first tilted position shows a first motif, in which the first foreground region appears with a motif color and the second foreground region and the background region appear with a background color different from the motif color, and- in a second tilted position shows a second motif, in which the second foreground region appears with the motif color and the first foreground region and the background region appear with the background color.
- The see-through security element according to at least one of claims 1 to 6, characterized in that the optically variable area pattern includes at least four subregions which are arranged in the form of a background region, of two foreground regions and an overlap region, and in which the inclination angles α and the azimuth angles θ of the facets and the interference layer are so mutually coordinated that the optically variable area pattern in transmission- in a first tilted position shows a first motif, in which the first foreground region and the overlap region appear with a motif color and the second foreground region and the background region appear with a background color different from the motif color, and- in a second tilted position shows a second motif, in which the second foreground region and the overlap region appear with the motif color and the first foreground region and the background region appear with the background color.
- The see-through security element according to at least one of claims 1 to 7, characterized in that the optically variable area pattern includes at least two subregions in which the facets have the same inclination angle α, but azimuth angles θ which differ by 180°.
- The see-through security element according to at least one of claims 1 to 9, characterized in that the optically variable area pattern includes a first and a second subregion in which the facets have the same inclination angle α0, but azimuth angles θ which differ by 180°, and a third and a fourth subregion in which the facets have different inclination angles α1 and α2 and in which the azimuth angle θ differs from the azimuth angle of the first and the second subregion by 90° or 270°.
- The see-through security element according to at least one of claims 1 to 10, characterized in that the optically variable area pattern includes at least three subregions in which the inclination angles α and the azimuth angles θ of the facets and the interference layer are mutually coordinated such that the subregions in a tilted position appear in red, green or blue in transmission.
- The see-through security element according to at least one of claims 1 to 11, characterized in that the facets are embossed into an embossing lacquer layer with a first refractive index, and over the interference layer there is applied a lacquer layer with a second refractive index that differs from the first refractive index by less than 0.3, in particular by less than 0.1.
- The see-through security element according to at least one of claims 1 to 12, characterized in that the interference layer is formed by a thin film element with semitransparent metal layers and a dielectric spacer layer, by a dielectric layer structure with at least one highly refractive layer, preferably combined with at least one lowly refractive layer, or includes at least one cholesteric liquid crystal layer.
- The see-through security element according to at least one of claims 1 to 13, characterized in that the facets are configured substantially as planar area elements; and/or the facets are arranged in a periodical grid and in particular form a sawtooth grating, or that the facets are arranged aperiodically.
- A method for manufacturing an optically variable see-through security element in which a substrate is made available and the substrate is supplied with a planar, optically variable area pattern which shows a colored appearance with a viewing-angle-dependent, polychrome color change in transmission, wherein- the optically variable area pattern is formed with a multiplicity of facets which have a substantially ray-optical effect and the orientation of which is distinguished respectively by an inclination angle α relative to the plane of the area pattern which is between 0° and 45°, and by an azimuth angle θ in the plane of the area pattern,- the optically variable area pattern is produced with at least two subregions respectively having a multiplicity of identically oriented facets, wherein the facets of the at least two subregions differ from each other with respect to the inclination angle relative to the plane and/or the azimuth angle in the plane, and- the facets of the at least two subregions are supplied with an interference layer with a viewing-angle-dependent color change in transmitted light.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE102014019088.9A DE102014019088A1 (en) | 2014-12-18 | 2014-12-18 | Optically variable see-through safety element |
PCT/EP2015/002414 WO2016096094A1 (en) | 2014-12-18 | 2015-12-01 | Optically variable transparent security element |
Publications (2)
Publication Number | Publication Date |
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EP3233512A1 EP3233512A1 (en) | 2017-10-25 |
EP3233512B1 true EP3233512B1 (en) | 2019-03-06 |
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EP15804317.4A Active EP3233512B1 (en) | 2014-12-18 | 2015-12-01 | Optically variable transparent security element |
Country Status (7)
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US (1) | US10124621B2 (en) |
EP (1) | EP3233512B1 (en) |
CN (1) | CN107087404B (en) |
AU (1) | AU2015366007B2 (en) |
CA (1) | CA2963024C (en) |
DE (1) | DE102014019088A1 (en) |
WO (1) | WO2016096094A1 (en) |
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DE102016015393A1 (en) * | 2016-12-22 | 2018-06-28 | Giesecke+Devrient Currency Technology Gmbh | Security element with reflective surface area |
JP2018114696A (en) * | 2017-01-19 | 2018-07-26 | 凸版印刷株式会社 | Display body |
DE102017009226A1 (en) | 2017-10-04 | 2019-04-04 | Giesecke+Devrient Currency Technology Gmbh | Optically variable see-through security element and data carrier |
JP7334414B2 (en) * | 2018-03-20 | 2023-08-29 | 凸版印刷株式会社 | Optical elements, transfer foils, and authenticators |
DE102018003030A1 (en) * | 2018-04-13 | 2019-10-17 | Giesecke+Devrient Currency Technology Gmbh | Security element, method for producing the same and equipped with the security element disk |
DE102018118473A1 (en) * | 2018-07-31 | 2020-02-06 | Bundesdruckerei Gmbh | Light control film, document with a light control film and method for producing a document with a light control film |
RU2712940C1 (en) * | 2018-12-26 | 2020-02-03 | Федеральное государственное казенное военное образовательное учреждение высшего образования "Военный учебно-научный центр Военно-воздушных сил "Военно-воздушная академия имени профессора Н.Е. Жуковского и Ю.А. Гагарина" (г. Воронеж) Министерства обороны Российской Федерации | Method for imaging an optoelectronic device |
DE102019003214A1 (en) * | 2019-05-07 | 2020-11-12 | Giesecke+Devrient Currency Technology Gmbh | Decorative element with multilayer structure and decorative equipment |
KR102214523B1 (en) * | 2019-07-31 | 2021-02-10 | (주) 나노메카 | Film structure for preventing counterfeit |
CN112572015B (en) * | 2019-09-30 | 2023-06-06 | 中钞特种防伪科技有限公司 | Optical anti-counterfeiting element and anti-counterfeiting product |
JP7368192B2 (en) * | 2019-11-15 | 2023-10-24 | ファナック株式会社 | Processing methods and articles |
DE102020000030A1 (en) * | 2020-01-03 | 2021-07-08 | Giesecke+Devrient Currency Technology Gmbh | Optically variable security element |
DE102020000031A1 (en) * | 2020-01-03 | 2021-07-08 | Giesecke+Devrient Currency Technology Gmbh | Optically variable security element |
EP3858606B1 (en) * | 2020-01-28 | 2022-09-07 | Cnbm Research Institute For Advanced Glass Materials Group Co., Ltd. | Coloured facade element with laminated pane structure |
AT523814B1 (en) * | 2020-05-08 | 2022-08-15 | Hueck Folien Gmbh | security element |
DE102020005932A1 (en) * | 2020-09-28 | 2022-03-31 | Giesecke+Devrient Currency Technology Gmbh | Optically variable security element with reflective surface area |
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- 2015-12-01 WO PCT/EP2015/002414 patent/WO2016096094A1/en active Application Filing
- 2015-12-01 EP EP15804317.4A patent/EP3233512B1/en active Active
- 2015-12-01 CA CA2963024A patent/CA2963024C/en active Active
- 2015-12-01 AU AU2015366007A patent/AU2015366007B2/en active Active
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AU2015366007B2 (en) | 2018-03-08 |
US10124621B2 (en) | 2018-11-13 |
CN107087404B (en) | 2018-12-25 |
CA2963024C (en) | 2019-06-25 |
AU2015366007A1 (en) | 2017-06-01 |
US20180037049A1 (en) | 2018-02-08 |
EP3233512A1 (en) | 2017-10-25 |
DE102014019088A1 (en) | 2016-06-23 |
CN107087404A (en) | 2017-08-22 |
CA2963024A1 (en) | 2016-06-23 |
WO2016096094A1 (en) | 2016-06-23 |
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