CA2642330A1

CA2642330A1 - Security element having an optically variable structure

Info

Publication number: CA2642330A1
Application number: CA002642330A
Authority: CA
Inventors: Roger Adamczyk; Christof Baldus; Karlheinz Mayer; Peter Franz
Original assignee: Individual
Current assignee: Giesecke and Devrient Currency Technology GmbH
Priority date: 2006-02-13
Filing date: 2007-02-05
Publication date: 2007-08-23
Anticipated expiration: 2027-02-05
Also published as: EP1986867B1; PL1986867T3; EP1986867A2; CN101421118B; WO2007093300A3; ATE519606T1; CA2642330C; RU2417897C2; WO2007093300A2; RU2008136571A; DE102006006501A1; CN101421118A

Abstract

The invention relates to a security element with an optically variable structure having an embossed structure with linear embossed elements and a coating, the embossed structure and the coating being so disposed that at least parts of the coating are completely visible upon perpendicular viewing but concealed upon oblique viewing.
Since substantially the total coating is formed from nonlinear primitives which are characterized by the parameters of outline form, size, color and orientation, and so combined with the embossed structure that different information is visible upon a change of viewing direction, the falsification security of the security element can be increased. The invention relates further to a method for producing such a security element, to a data carrier having such a security element, and to the use of such a security element or data carrier for product protection.

Description

Security element having an optically variable structure [0001] This invention relates to a security element having an optically variable structure which has an embossed structure with linear embossed elements and a coat-ing, the embossed structure and the coating being so disposed that at least parts of the coating are completely visible upon perpendicular viewing but concealed upon oblique viewing. The invention relates further to a method for producing such a secu-rity element, a data carrier having such a security element, and the use of such a secu-rity element or data carrier for product protection.

[0002] For protection against imitation, in particular with color copiers or other re-production methods, data carriers, such as bank notes, papers of value, credit or iden-tity cards, passports, certificates and the like, labels, packages or other elements for product protection are equipped with optically variable security elements. The protec-tion from forgery here is based on the fact that the optically variable effect, which is readily and clearly recognizable visually, is not rendered sufficiently or at all by the above-mentioned reproduction devices.

[0003] In this connection, CA 10 19 012 for example discloses a bank note which is provided in a partial area of its surface with a parallel printed line pattern. For pro-ducing the optically variable effect, a line structure is additionally embossed into the data carrier in the area of said printed line pattern, resulting in flanks that are visible only at certain viewing angles in each case. Targeted arrangement of the line pattern on flanks of like orientation causes the lines provided on the flanks to be visible upon oblique viewing of said flanks, while the line pattern is not recognizable upon oblique viewing of the back flanks. If phase jumps are provided in the line grid or in the em-bossed grid in partial areas of the embossed area, this permits information to be repre-sented that is recognizable either only from the first oblique viewing angle or only from the second viewing angle.

100041 Although such an optically variable security element shows a compara-tively sharp tilt effect to the viewer, the parallel printed line patterns with constant line spacing can nowadays be imitated with a certain effort by modern reproduction techniques. A further disadvantage is that the printed line patterns described in CA 10 19 012 do not allow any tilt effects with highly detailed and elaborately designed pic-ture motifs as a coating.

[0005] The invention is therefore based on the problem of proposing a security ele-ment of the type stated at the outset that avoids the disadvantages of known generic security elements and offers an increased degree of falsification security.
Further-more, a data carrier having such a security element and a method for producing such a security element are to be specified.

[0006] This problem is solved by the features of the independent claims.
Develop-ments of the invention are the subject matter of the dependent claims.

[0007] The optically variable structure of the inventive security element consists of a coating which is formed substantially completely from nonlinear primitives, and an embossed structure superimposed on said coating. The embossed structure has linear embossed elements which are so combined with the coating comprising nonlinear primitives that different infonnation is visible upon a change of viewing direction.
The nonlinear primitives are characterized by the parameters of outline fonn, size, color and orientation, and so combined with the embossed structure that the inventive shadowing effect results. With respect to the linear embossed elements the nonlinear primitives are thus so disposed that certain inforlnation results for a viewer in a top view of the security element, said infonnation changing upon a change of viewing direction.

100081 A line will hereinafter be understood to be a connection of two points ac-cording to the definition stated in "Taschenbuch der Mathematik," Bronstein, Se-mendjajew, 25th edition. This definition of course includes not only a straight con-nection but also a nonstraight, i.e. a curved, wavy or spiral, connection of two points in two- or three-dimensional space.

[0009] Applied to the present invention, this means that linear embossed elements are understood to be all three-dimensional elements whose projections into the plane of the optically variable element form a line according to the above definition.

[0010] The linear embossed elements are characterized as a rule by four flanks, said flanks having dimensions that permit the inventive shadowing effect. That is, the flanks inust be so dimensioned that, for the viewer looking at such a flank, informa-tion located behind said flank is at least partly concealed or shadowed.

[0011] Nonlinear primitives will hereinafter be understood to be all elements of two- and three-dimensional space whose outline fonn is so selected that they are not linear elements according to the above definition of a line. The nonlinear primitives of the present application are therefore, in geometric terms, derived from a single two-dimensional point and not from a two-dimensional connection of two points (line). The nonlinear primitives can thus generally be characterized as compact, nonelongate elements.

[0012] The use of nonlinear primitives of any outline fonn, size, color and align-ment makes it possible to give the coating of the optically variable structure a design so elaborate and highly detailed as to virtually rule out forgery at present.
The protec-tion from forgery is also increased according to the invention by the fact that substan-tially the total coating is formed from nonlinear primitives. A potential forger would thus have to imitate not only single areas but the total coating with extreme precision, which is virtually impossible at present.

[0013] Besides the increase in falsification security by using the embossed inven-tive coating, there is advantageously also a considerable increase in possible choices with regard to the motifs and geometric patterns to be used for the coating, as well as the freedom of design for the motifs and patterns, thereby resulting in considerably

-4-more impressive and optically more attractive tilt effects for the viewer upon suitable embossing of the coating. This makes the authenticity of an inventive security ele-ment easily ascertainable to the "man or woman on the street" as well. A
forged secu-rity element can be readily recognized by the fact that the dramatic tilt effect inherent in the authentic optically variable structure can be observed only to a very limited extent or not at all for a very elaborately designed coating.

[0014) The use of the inventive nonlinear primitives advantageously also makes it possible to realize tilt effects hitherto unknown in connection with generic security elements, with picture motifs or geometric patterns represented in true colors. Finally, a further advantage of the invention is that the superiinposition of primitives of dif-ferent color permits secondary color effects dependent on viewing direction.

[00151 The inventive primitives are characterized firstly by the parameter of out-line form. All outline forms can be used that are nonlinear according to the definition stated hereinabove. Although the outline form of the primitives can be varied within a very wide range, those primitives are preferred that have a circular, oval or poly-gonally bounded outline form. A primitive is polygonally bounded according to the present invention if it is a polygon in the mathematical sense. Conceptually, polygons are determined in two- or three-dimensional space. Therefore, it is possible to use polygons starting with triangles up to polygons with a large number of sides.
Particu-larly preferable polygons are various four-sided figures, such as parallelograms, squares, rectangles, rhombi and trapeziums. The nonlinear primitives can of course also have an outline form that is e.g. circular or oval in certain areas and polygonally bounded in other areas.

[0016] Besides said outline forms known from geometry, it is furthermore also pre-ferred that the linear primitives have an outline form determined by a symbol, geo-metric pattern and/or alphanumeric character. As symbols it is possible to use all nonlinear primitives that are accessible to the methods used for applying the coating.
These may be for example mathematical symbols, such as the integral or root symbol,

-5-or else the well-known sharp or double sharp symbol. Furthermore, it is possible to use characters, in particular alphanumeric characters, of all known fonts, although characters from the standard Latin and Greek fonts are particularly preferable. Fur-thermore, the outline of an inventive primitive can also be determined by a geometric pattern, e.g. the outline form of a snowflake or a guilloche pattern.

[0017] The nonlinear primitives characterized by a certain outline fonn can expe-diently have a filling which is preferably executed substantially all over. It is of course also conceivable, however, that the filling is screened, e.g. in the form of a dot screen, or that the primitive is determined only by a line defining the outline contour and thus has no filling. In this case, the color of the layer or layers located under the primitive can be recognized in the nonfilled inner areas of the primitives.

[0018] The size of an inventive nonlinear primitive will hereinafter be understood to be its dimension in one or more directions. Although it can be expedient for certain uses in the product production area to provide primitives with a dimension in the range of a few millimeters, it is particularly preferable if the nonlinear primitives have a dimension of 10 m to 500 m, in particular 20 m to 250 m. It goes without say-ing that a small dimension will increase the protection from forgery of the claimed security elements having an optically variable structure. Therefore, in particular coat-ings with a dimension of the primitives of e.g. 30 gm offer very great protection from forgery. At the same time, the dimension of the primitives is of course to be provided so as to permit the production of high-quality inventive security elements.

[0019] Unlike the coatings known for example from CA 10 19 012 having printed line patterns in which the dimension of the lines in the longitudinal direction is con-siderably higher than the dimension of the lines in the transverse direction, the inven-tive nonlinear primitives preferably have an outline form in which no dimension in any direction is more than four times the dimension in one of the other directions of the primitive.

-6-[0020] For it has turned out that particularly impressive tilt effects of the optically variable structures, at the same time as great freedom of design for the inventive coat-ing, can be obtained when the inventive primitives have a form that does not differ too much from the outline form of a circle, triangle or square, i.e. a compact element.
In such bodies, no dimension in any direction is more than approximately twice a di-mension in one of the other directions.

[0021] The coatings comprising the inventive nonlinear primitives can be a printed layer, in particular an offset, intaglio, screen, flexographic, xerographic, ink-jet or thermographic printed layer. Each of the stated printed layers has certain properties that are per se known to the expert, depending on the method used therefor.
The choice of a certain printed layer will therefore depend firstly on the intended use of ink, desired embossed structure, resolution, provided picture motif, etc.

[0022] Furthermore, it is preferred if the coating comprising nonlinear primitives is a layer incorporated by a laser printer or by the action of laser radiation of a laser.
Depending on the material used for the substrate of the optically variable structure, possible radiation sources here are CO2lasers, Nd:YAG lasers or other types of laser in the wavelength range from ultraviolet (UV) to far infrared (IR), whereby the lasers often also work with frequency doubling, tripling or even greater harmonic genera-tion. However, it is preferable to use laser sources in the near IR, since this wave-length range well matches the absorption properties of the materials provided for the optically variable structures. Since the spot size of the laser radiation can vary from a few microns to a few millimeters depending on the application case, the inventive primitives can be advantageously produced by the use of laser radiation. The continu-ous power of the lasers used therefor is normally between a few watts and a few hun-dred watts.

[0023] The inventive coating can fundamentally be formed from nonlinear primi-tives of any arrangement. Besides a completely random arrangement, e.g. an ar-rangement in the form of a fractal pattern is also possible. However, it is particularly

-7-preferable if at least a part of the nonlinear primitives is disposed in a preferably peri-odic grid. A grid arrangement of the primitives defines preferred directions of the coating which, when combined with a suitable embossed structure, lead to particu-larly impressive tilt effects. Although it is fundamentally possible that only a part of the nonlinear primitives is disposed in the form of a grid and the other part not in grid form, it is particularly expedient if all primitives forming the coating are disposed in the form of a grid, in particular periodic grid.

[0024] Independently of whether the primitives are disposed randomly or in a grid, primitives of different colors can overlap and produce a secondary color in the over-lap areas, whereby the arrangement of secondary colors in the overlap areas can in turn be per se a security feature of the coating.

[0025] According to a preferred embodiment, it is provided that groups of at least two nonlinear primitives of different color are disposed in the form of color primi-tives. The choice of colors and of type of primitives of a color primitive is fundamen-tally free, but colors of a primary color system are preferred. The use of color primi-tives permits the representation of elaborate and highly detailed picture motifs and geometric patterns, among other things.

[0026] The arrangement of the color primitives can again be effected completely randomly, in the form of a fractal pattern or in a combination of said two possible arrangements. It is particularly preferable, however, if at least a part of the color primitives is disposed in an, in particular periodic, grid. Such an arrangement is par-ticularly suitable for representing color pictures and similar motifs. It is of course also conceivable that a relatively large number of color primitives is disposed in a grid and the coating simultaneously has nonlinear primitives disposed randomly or likewise in grid form.

100271 Although the primitives or color primitives can be disposed in a grid with varying grid spacing, it is particularly expedient if the grid spacing of the grid is con-- g -stant for a part or the total coating. The thereby obtained regular arrangement defines one or more preferred directions in the plane of the coating and opens up, in combina-tion with an appropriately disposed embossed structure, particularly striking tilt ef-fects for the viewer.

[0028] The coating coinprising nonlinear primitives, or color primitives formed therefrom, can contain primitives of any color. However, primitives in the colors of a primary color system are particularly preferable. Furtherinore, coatings are claimed that have color primitives with nonlinear primitives in the colors of a primary color system. All primary color systems can be used that permit the application of a coating for the optically variable structure by the printing methods already described. How-ever, it is particularly preferable to use the primary color systems RGB (red, green, blue), CMY (cyan, magenta, yellow) and CMYK (cyan, magenta, yellow, key (black)).

[0029] It is furthermore particularly expedient if the optically variable structure has a multiplicity of color primitives that represent, upon perpendicular viewing, a multi-colored picture motif and/or geometric pattern whose visual impression varies upon a change of viewing angle. The color primitives representing the picture motif or pat-tern can have nonlinear primitives of any color or elements in the colors of a primary color system. As mentioned above, suitable embossing of the inventive coating makes it possible to produce elaborately designed and highly detailed picture motifs that are substantially completely visible in a top view, but upon a change of viewing angle only partly visible due to the shadowing effect.

[0030] In a special einbodiment, the color primitives correspond to the pixels of the picture motif and/or geometric pattern, said pixels having certain color compo-nents of a color system associated therewith. The color primitives have nonlinear primitives with colored areas in the colors of the color system, the size of the colored areas of the nonlinear primitives corresponding to the particular color component of the pixels. The color effect of a color primitive therefore results for the viewer from the size of the areas covered with the particular colors. The areas can be directly adja-cent each other or also maintain a certain distance apart so that the color effect of the color primitive is ultimately also influenced by the color of the light reflected by the base surface. According to this special embodiment, it is thus possible to represent picture motifs and geometric patterns in true colors, whereby the number of pixels of the picture motif or pattern at the same time corresponds to the number of color primitives. It should be noted that, in a top view, the true color of a color primitive results as the secondary color of the nonlinear primitives forming the color primitive if the dimensions of the colored areas are below the viewer's visual resolution.

100311 According to a further advantageous embodiment of the security element, it is provided that at least two grids coinprising nonlinear primitives of one color in each case form a picture motif and/or geometric pattern. The arrangement of the grids defines areas in which the nonlinear primitives of different grids overlap and produce a secondary color in said areas. To produce as definite a secondary color as possible in the overlap area, nonlinear primitives with a well defined outline fonn and an all-over filling are particularly preferable for forming the grids. The grids can of course contain primitives in the colors of a primary color system, thereby causing the secon-dary colors produced in the overlap areas to in turn be well defined secondary colors of a subtractive color mixture. Since the grids used do not cover the substrate material all over as a rule, there is light reflection in the bare areas of the substrate. The re-flected light and the overlap areas of subtractive color mixture ultimately yield an additive (autotypic) color mixture perceived by the observer.

[0032] It is further particularly preferable if the areas of overlapping primitives correspond to the pixels of the picture motif and/or geometric pattern, said pixels hav-ing certain colors of a color system associated therewith, and the secondary color of the areas of overlapping primitives corresponds to the particular color of the pixels, so that the color effect of the picture motif and/or geometric pattern varies upon a change of viewing angle. In this case, a pixel of the motif or pattern is thus repre-sented by a secondary color produced by subtractive color mixture. Depending on the degree of coverage of the substrate by the overlap areas of the grids, an additive color mixture ultimately also results for the viewer to a certain degree through the light re-flected by the substrate.

100331 If the nonlinear primitives or color primitives are disposed in the form of a grid, such a regular arrangement of the primitives or color primitives defines at least one preferred direction in the plane of the coating. It is particularly preferable that the linear embossed elements are disposed in the direction of the at least one preferred direction at least in certain areas, so that when the areas provided with embossed structures are viewed perpendicular to the at least one preferred direction the visual impression varies in dependence on viewing direction. For it has turned out that the tilt effect perceptible to the viewer upon a change of viewing angle is particularly pronounced with an arrangement of the embossed elements in a preferred direction.
The tilt effect will furthermore be particularly impressive if different areas of the coating are provided with embossed elements that are disposed in a preferred direc-tion in each case. The preferred direction itself can be caused by the outline fonn and/or the arrangement of the primitives or color primitives in the grid.
Therefore, a preferred direction can be defined by the arrangement and simultaneously by the out-line contour of the primitives forming the grid.

[0034] The optically variable structure can have additional information which arises by variation of the coating and/or of the embossed structure. The additional information can be recognizable from one or more viewing directions. It is also pos-sible that the additional infonnation runs into second, third, etc., additional informa-tion depending on the viewing angle.

[00351 The additional information can arise for example by a variation of the fonn, color and/or the arrangement of the nonlinear primitives, such as offset, change of grid spacing, omission, reflection of single or several nonlinear primitives.
The addi-tional information can also have information in the coating that individualizes the optically variable element, such as alphanumeric characters or bar codes.

[0036] Although the inventive optically variable structure of the security elements can contain linear embossed elements of any arrangement, it is particularly preferable if the embossed elements are disposed in the form of an embossed grid with a grid spacing. The grid spacing of the embossed structure can correspond to the grid spac-ing of the coating grid. If the grid spacings of the coating and of the embossed struc-ture are not identical but shifted by a certain value, however, this yields interesting beat effects dependent on viewing direction.

[0037] The additional information can advantageously also arise by a variation of the form, size, height and/or the arrangement of the linear embossed elements, such as offset, change of grid spacing, omission of single or several linear embossed ele-ments. The additional information by variation of the embossed structure is strength-ened by a simultaneous variation of the coating.

[0038] In a further advantageous embodiment, it is provided that the optically vari-able structure is subdivided into partial areas in which different partial embossed structures and/or partial coatings are disposed. If the linear embossed elements of the embossed structure or the nonlinear primitives are disposed in the fonn of a grid with a grid spacing, an expedient embodiment results from the partial embossed structures or partial coatings being offset in at least two adjacent partial areas by a fraction, in particular a third, of the grid spacing. Furtherinore, parts of the partial embossed structures can also have an unembossed edge contour so as to be better recognizable.
[0039] In connection with this matrix-like arrangement of the partial embossed structures and the production of additional information in the area of the embossed structures or the coating, express reference is made here to WO 97/17211 and WO
02/20280 Al.

[0040] The inventive optically variable structure forms a security element that is difficult to imitate and can be disposed directly on any data carriers. The optically variable structure can also be part of a security element having further security fea-tures besides the optically variable structure.

[0041] The security element can for example have in the area of the optically vari-able structure a further ink layer which is preferably translucent and which is dis-posed congruently with the raised areas of the embossed structure. Here, too, a great variety of embodiments are possible. Some are for exainple already described in WO
2004/022355 A2, to which express reference is likewise made in this connection.
[0042] According to a further embodiment, the security element can have further layers and authentication features, such as a metallic layer, a metallic effect layer, an additional translucent, optically variable layer or a foil element. Such layers and ele-ments can be superimposed on optically variable structures or underlaid thereunder.
The coating combined with the linear embossed elements can of course also be such a metallic layer, a metallic effect layer or optically variable layer.

(0043] Finally, it is also possible to equip the coating or the printing inks used for producing the primitives and color primitives, and/or the ink layer disposed congru-ently with the raised areas of the embossed structure, at least partially with machine-readable properties. For this purpose it is possible to use e.g. magnetic, electrocon-ductive, luminescent additives. Additives absorbent in a certain wavelength range, preferably in the UV or IR region, can also be used advantageously.

[0044] The inventive optically variable structure or the inventive security element is preferably applied to data carriers, such as security documents and value docu-ments, such as bank notes, shares, bonds, certificates, coupons, credit cards or identity cards, passports or the like. The data carriers are thus equipped with a security ele-ment easily recognizable even to laymen for increasing the falsification security.
However, the optically variable structure or the inventive security element can also be used very advantageously in the area of product protection. Here, the optically vari-able structure or the security element can be applied to suitable labels or packages or the goods themselves.

[0045] If paper is used as the data carrier material, it is possible to use in particular cotton vellum papers, paper-like materials made of plastic films, plastic-film-coated or laminated paper or multilayer composite materials.

[0046] For producing the inventive security element or the optically variable struc-ture, any substrate is preferably first provided with the coating comprising nonlinear primitives, and the embossed structure then produced in register with said coating.
However, it is fundamentally also possible to provide the method steps in the reverse order. The coating is preferably printed on or transferred to the substrate by the ther-motransfer method here. The coating can be produced by any printing process, such as planography, e.g. the offset process, relief printing, e.g. the letterpress or flex-ographic process, screen printing, gravure printing, e.g. halftone gravure or intaglio printing, or a thermographic process. Furthermore, the coating can preferably also be produced by a laser printer or by the action of laser radiation.

[0047] For producing the einbossed structure, any methods can likewise be used.
The embossed structure is preferably produced by means of an embossing tool, which can be for example an intaglio printing plate. The embossing is produced here as a blind embossing with the help of an inkless intaglio printing plate. According to a special embodiment, however, the embossed structure can also be produced by inta-glio printing with ink. This production variant can be used in particular for embodi-ments in which a further ink layer is provided congruently with the embossed struc-ture.

[0048] For producing the embossing tool, a plate surface is for example milled with a graver or a laser. The plate surface used can be any material, such as copper, brass, steel, nickel or the like. The graver used for milling preferably has a flank angle of approx. 40 and a rounded point approaching a spherical segment or sector.
The embossing tool can be milled as a one-up unit or already as a multi-up unit.

[0049] The order of the two method steps can fundamentally be selected freely.
As a rule, the coating is first applied and then embossed. The relief height and shaping of the embossing is thus spared from further influences occurring for example in a sub-sequent printing operation.

[0050] The alternative, namely first embossing and then applying the coating, of-fers the advantage of higher color brilliance and a more sharply contoured print, how-ever. This effect comes from the fact that the substrate is simultaneously calendered during embossing and thus acquires a smoother, less absorbent surface.

[0051] Furtherinore, application of the coating before embossing offers the advan-tage that the coating can be disposed solely on the flanks of the embossed elements or else solely in the zeniths/amplitudes of the embossed elements. This makes it possible to obtain particularly impressive shadowing effects. Unlike intaglio printing with ink, in which embossing and application of the coating are effected simultaneously and the coating can be disposed solely in the area of the zeniths/amplitudes of the em-bossed elements, the separation of the method steps of embossing and application of the coating opens up much greater latitude for design. In particular a process control by which the coating is first disposed on the substrate and the embossed structure is then produced with high register accuracy permits the above-mentioned selective ar-rangement of the coating solely on the flanks of the embossed elements, while the zeniths/amplitudes of the embossed elements have no coating. With respect to the arrangement of the coating solely in the zeniths/amplitudes or flanks of the embossed elements, the disclosure of WO 97/17211 is included in the present application. Fur-thermore, the description of the figures of the present application will also indicate further details and advantages for the selective arrangement of the coating on the flanks or the zeniths/amplitudes.

[0052] With reference to the following examples and supplementary figures, the advantages of the invention will be explained. The described single features and sub-sequently described embodiments are inventive when taken alone but also inventive in coinbination. The examples represent preferred embodiments, but without in any way restricting the invention. The proportions shown in the figures do not correspond to the relations existing in reality and serve solely to improve the clearness.

[0053] The schematic drawings are described as follows:
Fig. 1 an inventive data carrier, Fig. 2 a section along the line A-A from Fig. 1, Fig. 3 a first inventive coating in a top view, Fig. 4 a second inventive coating in a top view, Fig. 5 a third inventive coating in a top view, Fig. 6 a fourth inventive coating in a top view, Fig. 7 a fifth inventive coating in a top view, Fig. 8 a sixth inventive coating in a top view, which is a variant of the coating of Fig. 7, Fig. 9 an embossed structure with linear embossed elements in a top view, Fig. 10 a further inventive coating with nonlinear primitives disposed in the fonn of a grid, Fig. 11 a perspective view of an inventive optically variable structure formed from the embossed structure and coating shown in Fig. 9 and Fig. 10, respec-tively, Fig. 12 a further embossed structure with nonlinear embossed elements, Fig. 13 a further inventive coating with nonlinear primitives disposed in the fonn of a grid, Fig. 14 a perspective view of a further inventive optically variable structure formed from the embossed structure and coating shown in Fig. 12 and Fig.
13, respectively, Fig. 15 a further inventive coating with three different types of nonlinear primi-tives which are disposed in the form of a grid, Fig. 16 the inventive coating from Fig. 15 with preferred directions marked for three areas of the coating, Fig. 17a a further inventive coating with nonlinear primitives disposed in grid fonn, Fig. 17b the coating from Fig. 17a with three marked preferred directions and sche-matically shown embossed structures corresponding thereto, Fig. 18a a further inventive coating with nonlinear primitives disposed in grid forin, Fig. 18b three preferred directions resulting from the grid arrangement according to Fig. 18a, Fig. 18c a further inventive coating with color primitives disposed in grid form, Fig. 18d three preferred directions resulting from the grid arrangement according to Fig. 18c, Fig. 19 a further inventive coating with color primitives disposed in grid form, the coating having additional information, Fig. 20 a detail of a picture motif shown in Fig. 1, in a black-and-white representa-tion, Fig. 21 the detail according to Fig. 20 in the form of an inventive coating with nonlinear primitives disposed in grid form, Fig. 22 the detail from Fig. 20 in the fonn of a further inventive coating, Fig. 23 a further inventive coating with color primitives disposed in the form of a grid, Fig. 24 the coating of Fig. 23 with two preferred directions resulting from the grid, and embossed elements disposed along said preferred directions, in a top view, Fig. 25 a detail of Fig. 20 with a preferred direction for the arrangement of the lin-ear embossed elements, Fig. 26 a further picture motif with a plurality of preferred directions for the ar-rangement of the linear embossed elements, Fig. 27 a further embossed structure with linear embossed elements, Fig. 28 a further inventive coating with nonlinear primitives disposed in the forln of a grid, whereby nonlinear primitives of different grids overlap in certain areas, Fig. 29a a further inventive coating with overlapping primitives of different colors and three preferred directions of the coating, Fig. 29b the inventive coating from Fig. 29a with additional information disposed in the coating, Fig. 29c the inventive coating from Fig. 29a with further additional infonnation disposed in the coating, - 1$ -Fig. 30 a further inventive coating with a marked direction which does not corre-spond to a preferred direction of the coating, Fig. 31 a cross section through an embossed structure with additional information, Fig. 32 a further embossed structure in cross section with different additional in-formation, Fig. 33 a further embossed structure in cross section with embossed elements which are disposed in a grid with large grid spacing, Figs. 34a-34p cross sections through different linear embossed elements, Fig. 35a an inventive data carrier in cross section before embossing, Fig. 35b an inventive data carrier in cross section after embossing, Fig. 36a a further inventive data carrier in cross section before embossing, Fig. 36b the further inventive data carrier after embossing done with ink.

100541 Fig. 1 shows an inventive data carrier 1 in the fonn of a bank note with an optically variable structure 3 which is placed in the printed image area 2 of the data carrier 1 and in the unprinted area. The optically variable structure 3 is used accord-ing to the invention as a so-called human feature, i.e. as a feature testable by a human without aids, possibly alongside further features for detecting the authenticity of the data carrier. Providing such features is particularly expedient in bank notes, but also in other cash-equivalent documents, such as shares, checks and the like. Data carriers according to the invention may also be labels, passports or cards as are used nowa-days e.g. for identifying persons or goods or for performing transactions or services.
[0055] The optically variable structure 3 can be of different structure, in conjunc-tion with the resulting different effects from different viewing directions.
According to a preferred embodiment, the optically variable structure 3 consists of a one or multi-colored coating contrasting with the surface of the data carrier, such as a pat-tern, picture or alphanumeric information, which is produced by printing technology or in another way, for example by a transfer method or by the action of laser radia-tion. Depending on the design of coating and einbossed structure and their mutual association, the embossed structure interacting with the coating produces the inven-tive effects to be used for the authenticity check.

[0056] All optically variable structures according to the invention have in common that they and the resulting effects cannot be imitated using currently known reproduc-tion techniques, in particular copying machines, since copying machines can only render the optically variable structure from one viewing direction so that the optically variable effect is lost. Furthermore, imitation will generally also fail because the reso-lution of the reproduction apparatuses is too low.

[0057] Hereinafter, some examples of different preferred embodiments of the in-vention will be explained with reference to the figures. The representations in the fig-ures are greatly schematized for purposes of better understanding and do not reflect the actual conditions.

[0058] The embodiments described in the following examples are reduced to the essential information for better comprehensibility. In actual iinplementation it is pos-sible to use considerably more complex patterns or pictures in single- or multicolor printing as a coating. The same applies to the embossed structures. The information represented in the following examples can likewise be replaced by picture or text in-formation as elaborate as desired. Production of the coating e.g. as a print normally exploits the possibilities of printing technology. Typical dimensions of nonlinear primitives as of approx. 10 m are used. The linear embossed elements forming the embossed structure have as a rule an embossing height in the range of 10 m to gm, preferably 50 m to 120 gm. The various embodiments are not restricted to use in the described form either, but can also be combined with each other to enhance the effects.

[0059] Further, only the design and mutual association of the embossed structure and the coating are shown in the following examples to perinit a clear presentation of the optical effects of the inventive optically variable structure.

Example 1(Figures 2 to 14 and Fig. 34) [0060] Fig. 2 shows a schematic sectional view along the line A-A (see Fig. 1) and in connection with Figures 3 and 4 of an optical variable structure in which the em-bossed structure 4 is formed of regularly disposed, uniform, linear embossed elements 5, i.e. designed as a periodic line screen. The linear embossed elements 5 are provided with a coating 7 which is formed as a multi-colored arrangement of nonlinear primi-tives. The individual color areas of the nonlinear primitives are located on the flanks of the linear embossed elements. The formation of the linear embossed elements 5 as elevations, which are preferably produced by embossing the data carrier, can be clearly recognized in the sectional view on the upper side of the data carrier. If the data carrier is mechanically defonned with an embossing tool, the underside of the data carrier material shows the negative deformation. The defonnation is shown only schematically here. The back of the data carrier will in general not have an embossing that is so pronounced and true to the embossing die. Hereinafter, only the upper or front side of the data carrier essential for understanding the invention will be de-scribed as it is perceived by the viewer in a top view from the viewing direction AU.
Deformation of the underside or back is not essential to the invention but merely con-comitant to special embossing techniques, such as intaglio printing. However, it can serve as a further authentication feature.

[0061] The inventive coating 7 is shown more closely in Figures 3 and 4.
Accord-ing to Fig. 3 the coating 7 is formed from nonlinear primitives 8 and 13 disposed regularly in the form of a grid. The elements 8 and 13 are of different colors, which is symbolized by the different filling of the circles fonning the primitives 8 and 13. Be-sides the primitives with a circular outline form shown in Fig. 3, two further outline fonns of the primitives are shown in Fig. 4. The outline of the primitives 13 is that of a syinmetrical cross, whereas the outline of the elements 8 corresponds to a star, which can also be regarded as a special decagon. The primitives 8 and 13 of Fig. 4 are also disposed in grid form. The elements 13 in Figures 3 and 4 are offset from the elements 8 by half a grid spacing in a direction 17 extending from below to above in Fig. 3. The nonlinear primitives 13 are also offset from the primitives 8 in a direction, not specified in Figures 3 and 4, perpendicular to the direction 17.

[0062] The preferred direction 17 oriented from below to above in Fig. 3 is defined by the grid arrangement of the primitives 8 and 13. Along said preferred direction 17 a linear embossed element of the embossed structure can be disposed so that the structure comprising coating 7 and embossed structure 4 as shown in cross section in Fig. 2 ultimately results if the primitives 8, 13 are so embossed with the embossed element 5 that they come to lie approximately symmetrically to the center of the em-bossed element. To arrive at the structure of Fig. 2, a linear embossed element 5 with an approximately semicircular cross section, as shown in Fig. 34d, must further be produced in the substrate.

[0063] To obtain a sharper tilt effect, a cross section according to Figure 34c or 34h can be selected for the embossed elements. Even greater strengthening of the tilt effect results from the choice of a profile according to Figure 34a, 34b or 34f. Fur-thermore, other embossed element cross sections shown in Fig. 34 can also be com-bined advantageously with the coating 7.

[0064] As can be easily seen in Figures 2 and 3, the total coating formed from the primitives 8 and 13 is visible in a substantially perpendicular top view of the inven-tive optically variable structure. Upon a change of viewing direction from the top view (AU) to an oblique view from direction B, however, the primitives 8 disposed on a flank of the linear embossed elements 5 will dominate the visual picture, while the primitives 13 disposed on the other flank of the linear embossed elements 5 are partly or completely concealed (shadowed) by the embossed elements 5. Upon oblique viewing of the optically variable structure from direction C, the primitives 13 dominate the visual impression and the primitives 8 are wholly or partly shadowed.
This basic principle inherent in the inventive optically variable structures 3 is realized analogously if the linear embossed elements 5 are not straight, as in Fig. 3, but have the fonn of a wavy or curved line. The line 6 shown for illustrating such an emboss-ing in Fig. 4 is only for illustration's sake. It is of course also possible to emboss a considerably more complicated pattern, e.g. a spiral pattern, into the base surface.
[0065] Hereinafter, further inventive coatings will be described with reference to Figures 5 to 8. The coating 7 in Fig. 5 shows primitives 8, 9 of different color whose outline form corresponds to that of a symmetrical "L". The primitives 8 and 9 are dis-posed in a regular grid in such a way that a primitive 8 is combined with a primitive 9 in each case. The primitives 8 and 9 thus form in pairs a color primitive 52, which will be dealt with in more detail.

[0066] A further variant of the coating 7 is shown in Fig. 6. The coating 7 here consists of regularly disposed, nonlinear primitives 8, 9 and 13 which in each case have the outline form of an arched element. The primitives assume the positions of a grid with constant grid spacing.

[0067] It is also possible that the primitives, as shown in Figures 7 and 8, have an outline form complementary to the outline form of an adjacently disposed primitive so as to yield a substantially all-over coating 7. While having basically the same out-line fonn, the elements can also be disposed so as to yield additional inforination in the coating, as shown in Fig. 8.

[0068] With reference to Figures 9 to 14, further inventive optically variable struc-tures will be dealt with in detail. Fig. 9 shows an embossed structure 4 consisting of three linear embossed elements 5 with a triangular cross section. Each embossed ele-ment 5 has four flanks which rise above the plane formed by the substrate. The flanks extending in the longitudinal direction of the linear embossed element 5 are desig-nated with the reference signs 5a and 5b in Fig. 9, while the two flanks present at the ends of the embossed element 5 are provided with the reference signs 5c and 5d. The grid spacing of the grid determining the arrangement of the linear embossed elements is designated x.

[0069] Fig. 10 shows a coating 7 that yields in combination with the embossed structure of Fig. 9 the optically variable structure shown in Fig. 11. The coating 7 consists of two types of nonlinear primitives with a different outline and different color. The primitives 8 have a polygonally bounded outline form in the form of a rec-tangle. Each primitive 9, however, has the outline form of a square and an area ap-proximately half as great as the area of a primitive 8. The primitives 8 and 9 are dis-posed at regular intervals on the positions of a grid. Each pair of primitives

8 and 9 forms a color primitive 52 which is disposed in a grid cell 12. The grid spacing x of the coating 7 corresponds to the grid spacing x of the embossed structure 4 of Fig. 9.
[0070] When a substrate provided with the coating 7 is provided in exact register with the embossed structure 4 from Fig. 9 this yields the combined structure from Fig.
11. While the total coating 7 is visually ascertainable in a vertical top view of the structure shown in Fig. 11, fundamentally only the grid arrangement of the nonlinear primitives 9 on the flanks 5b of the embossed elements 5 can be perceived upon oblique viewing from direction B. Conversely, only the primitives 8 on the flanks 5a of the linear embossed elements 5 can be seen from viewing direction C. With the arrangement of the primitives 9 at the base of each flank 5b as shown in Fig.
11, the primitives 9 disposed between a plurality of linear embossed elements 5 are shad-owed very quickly by the flanks 5b of adjacent embossed elements 5 when the angle of vision changes from a substantially perpendicular top view (AU in Fig. 2) to view-ing from direction B. Since the primitives 8 are so disposed, on the other hand, that they come to lie on the flanks 5a of the embossed elements 5 close to the amplitude 20, they can be seen on the flanks 5a over a wide angular range due to the lesser shadowing by the embossed elements upon a change of viewing from a substantially perpendicular top view to oblique viewing from direction C.

[0071] Fig. 12 shows an embossed structure 4 varied with respect to the structure shown in Fig. 9. It comprises a linear embossed element 5 extending along a first pre-ferred direction 16. Perpendicular thereto, three further linear embossed elements 15 are disposed along a second preferred direction 17. The grid spacing of the embossed element 5 is x, the grid spacing of the embossed elements 15 is y. In the present case the grid spacings x and y are equal.

100721 Fig. 13 shows an inventive coating 7 which is fonned by a grid arrangement of the nonlinear primitives 8 and 9, both primitives having a rectangularly bounded outline form and different colors. The primitives 8 and 9 again form a color primitive 52 which is disposed in a grid cell 12. The combination of the embossed structure 4 from Fig. 12 and the coating 7 from Fig. 13 yields the combined structure shown in perspective in Fig. 14. Viewing from directions B and C yields this time a completely different picture from Fig. 11, since the linear embossed elements 5 and 15 are dis-posed along two preferred directions. From direction C substantially only the primi-tives 8 disposed on the flanks 5a can be seen, while from direction B the primitives 9 disposed on the flanks 5b, unless they are shadowed by adjacent embossed elements.
100731 From direction D, on the other hand, the elements 8 can be seen, and from direction E the elements 9. The arrangement of the primitives on the particular flanks of the embossed elements also has an influence on the color shift effect of this struc-ture.

Example 2 (Figures 15 and 16) 100741 The inventive coating 7 shown in Figures 15 and 16 comprises three types of different-colored and nonlinear primitives 8, 13 and 39 which are in each case dis-posed in the fonn of a grid with constant grid spacing. Furthermore, one primitive 8, 13 and 39 in each case are printed on the substrate (not specifically shown) so as to form a color primitive 52. In accordance with the regular arrangement of the individ-ual elements, the color primitives 52 are also disposed in the form of a regular grid with constant grid spacing. One color primitive 52 is located in a grid cell 12 of the grid in each case. The thus obtained regular arrangement of color primitives 52 is di-vided into three partial areas A, B and C in the shown preferred embodiment.
Each partial area is provided with an embossed structure 4 (not shown) comprising linear embossed elements 5. The alignment of the embossed structure 4 is effected in each partial area parallel to the preferred directions of the grid, whereby in Fig.
16 only one preferred direction is marked for each area A, B and C and used for aligning the embossed structure. As in the above-described optically variable structures, an opti-cally variable effect dependent on viewing direction results for the embossing of the coating 7 shown in Figures 15 and 16. While in a top view the total coating 7 can be perceived by a viewer, any other oblique viewing directions yield interesting tilt ef-fects which are different for the single areas A, B and C since the embossed structures in each case have different orientations in said areas.

Example 3 (Figures 17a, 17b, 18a and 18b) [0075] The coating 7 shown in Figures 17a and 17b is formed from three circular primitives 8, 9 and 13 of different color which again define a color primitive 52 in a grid cell 12 of a regular grid. The arrangement of the primitives 8, 9 and 13 again de-termines preferred directions along which an embossing is effected. In Fig.
17b the preferred directions 16, 18 and 19 are marked and the embossed structures 64 shown schematically along the preferred directions. The cross section of the linear embossed elements is triangular and corresponds to the cross section shown in Fig. 34a.
The embossed structure 64 has amplitudes or zeniths 20 and valleys 21 located therebe-tween. Therefore, the nonlinear primitives 8 and 9 come to lie on one flank of the nonlinear embossed element upon an embossing of the coating 7 along the preferred direction 16, while the elements 13 come to lie on the other flank of the element.
[0076] If the dimensions of the primitives 8, 9 and 13 are selected so that they are no longer perceived as separate elements by the human eye, a secondary color recog-nizable in a top view results for a color primitive 52 defined by the primitives 8, 9 and 13. Depending on the area coverage of the color primitive 52 in the grid cell 12, the viewer perceives a secondary color resulting from the secondary color of the color primitive 52 and the color of the substrate surface on which the coating is disposed.
Upon viewing from a direction different from the perpendicular top view (AU in Fig.
2) a secondary color resulting from the colors of the primitives 8, 9 and the color of the substrate surface is observed in the area of the linear embossing along the direc-tion 16 on a flank of the embossed element. From a direction opposite this viewing direction, however, the secondary color comprising the color of the primitives 13 and the color of the base surface is perceived on the other flank of the embossed element.
It is evident from Fig. 17b that the secondary color resulting for the individual flanks of the embossed element changes in case of an embossing along the preferred direc-tion 19. In this case, a secondary color comprising the colors of the primitives 8, 9 and 13 and the color of the base surface results upon viewing of one flank.
The per-ceived secondary color of the opposite flank, however, is defined by the color of the differently spaced elements 8, 9 and 13 and the color of the base surface.

[0077] Fig. 18a shows a further inventive coating 7 wherein triangular primitives 8, 9 and 13 are disposed in the form of a relatively large regular triangle.
The ar-rangement of the primitives 8, 9 and 13 again defines a color primitive in each grid cell 12 of a grid. Compared to the color primitives 52 shown in Fig. 17a the color primitives of Fig. 18a are characterized by a greater coverage of the base surface.
Therefore, the color effect that can be perceived by the viewer in a top view of a grid cell is determined to a greater extent by the inherent color of the triangular primitives 8, 9 and 13 or the color primitive. Furthermore, said primitives again define preferred directions in the plane of the coating 7, which are shown by the reference signs 16, 18 and 19 in Fig. 18b. If an embossing is effected along said preferred directions with an embossed structure having a pointed profile, e.g. the profile from Fig. 34a, 34b or 34f, this yields color shift effects with extremely pronounced dependence on viewing di-rection. If for example the colors of the primary color system CMY are used for the primitives 8, 9 and 13, this yields for the coating 7 in a top view a substantially gray secondary color for the color primitives 52, which is somewhat brightened by an e.g.
white inherent color of the substrate.

Example 4 (Figures 18c and 18d) [0078] Figures 18c and 18d show a further variant of the inventive coating 7.
The nonlinear primitives 8, 9 and 13 again form a color primitive 52 in a grid cell 12 of a regular grid. The triangular primitives 8, 9 and 13 have the colors of a primary color system, for example those of the primary color system CMY. In the shown example, the triangles 8 have the color cyan, the triangles 9 the color magenta and the triangles 13 the color yellow.

[0079] Unlike the coating grid of Fig. 18a, the coating 7 from Fig. 18c comprises two grids which are offset in the horizontal direction (direction 16 in Fig.
18d). As is apparent from Fig. 18c, the color primitives 52 of the first and third lines of the shown coating belong to a grid, while the color primitives 52 of the second line are disposed in the grid cells 62 of the second grid. The grid cells 62 are offset from the grid cells 12 of the first grid by half a grid spacing in the horizontal direction 16.
[0080] Again, three preferred directions 16, 18 and 19 result for the arrangement of the linear embossed elements (see schematic embossed structure 64). If an embossed element is superimposed on the second line of the coating 7 in direction 16, for ex-ample, solely yellow triangles 13 come to lie on one flank of the embossed element with an e.g. triangular cross section. When viewing said flank the viewer therefore sees solely yellow triangles 13 and the color of the base surface, e.g. white, ultimately yielding a bright yellow color. Conversely, he can perceive on the other flank of the embossed element disposed in direction 16 a secondary color recognizable from the colors magenta and cyan of the primitives 9, 8 and the white base surface areas.

[0081] Analogously, the arrangement of a linear embossed element along the pre-ferred direction 18 yields a perception dependent on viewing direction, whereby one flank of the embossed element, due to the magenta triangles solely disposed there, shows a magenta color brightened by the color of the base surface. Viewing of the other flank of the embossed element, however, yields a secondary color from the color of the base surface and the colors yellow and cyan of the primitives 13, 8.
[0082] Finally, the arrangement of an embossed structure along the preferred direc-tion 19 will yield for one flank the pure brightened color cyan, and the other flank a secondary color from the color of the base surface and the colors magenta and yellow of the primitives 9, 13.

100831 A top view of the coating 7 of Figures 18c and 18d again yields for each color primitive a gray secondary color from the color of the primitives 8, 9 and 13.
The general impression of the coating is therefore again a somewhat brightened gray tone due to the white hue of the base surface. In the above discussion of secondary colors, a secondary color of the color primitives always results when the dimensions of the color areas of the individual primitives are below the resolution of the human eye.

Example 5 (Fig. 19) [0084] Fig. 19 shows a coating 7 similar to the coating shown in Figures 18a and 18b. However, in some grid cells of the coating 7 the arrangement of the primitives 8,

9 and 13 of a color primitive 52 is different from the other grid cells 12.
The grid cells with a different arrangement of the elements are provided with the reference sign 22 and ultimately forin additional inforination within the coating. Depending on the alignment of the embossed structure with respect to the color primitives disposed in grid form, said additional information can be perceived in a top view and from certain directions. It constitutes an additional security feature which is inherent in the inven-tive coating 7.

Example 6 (Figs. 20 to 26) [0085] Hereinafter, the production of secondary color effects by the inventive opti-cally variable structure will be dealt with in depth. Fig. 20 shows a detail of the pic-ture motif rendered in the printed image area 2 of the data carrier 1 of Fig.
1. It can be disposed with nonlinear primitives of a color, e.g. black, on a substrate.
Furthermore, an embossed structure is provided which extends in a certain direction in certain areas of the coating. An example thereof is shown in Fig. 25 for the eye area of the picture motif.

[0086] As shown in Fig. 21, the picture detail can also be effected by nonlinear primitives disposed in grid form, which have one or different outline fonns and one or different colors. In the present case, the coating of the picture motif is fonned by primitives 39 with a circular outline fonn, the primitives 39 having a filling of vary-ing degree for producing a coverage associated with a certain area of the picture mo-tif. For example, the primitives 39 are filled substantially completely in the area of the depicted person's hair, whereas the primitives 39 in the area of the forehead are circu-lar rings in whose center the color of the base surface, e.g. white, can be perceived.
Furthermore, the color of the primitives can be varied for the individual image areas.
[0087] Further, Fig. 22 shows the picture detail from Figs. 20 and Fig. 21 with a coarser grid comprising primitives 13. A pair of arched or circular segment shaped primitives 13 is disposed in each case in a regular grid. By variation of the area filling of the individual primitives 13 the picture detail can be rendered with sufficient con-trast. It is of course also possible that a pair of primitives 13 of different color is dis-posed in each case so as to fonn a color primitive, and a certain color primitive shows in a top view a secondary color that is derived from the color of the primitive pair and the color recognizable in a grid cell from the base surface. The inventive coatings shown in Figures 21 and 22 are also provided with suitable embossed structures, whereby different alignments of the embossed elements are again provided in single image areas. Although a picture motif with straight partial areas defines a multiplicity of preferred directions (see Fig. 26 with the preferred directions 16 to 19), striking preferred directions can also be found for the image areas of Figures 21 and 22, as shown by way of example in Fig. 25.

[0088] The interaction of color primitives and linear embossed structure for achieving impressive color shift effects with secondary colors will be described in detail with reference to Figures 23 and 24. The inventive coating 7 shown in Fig. 23 can be a greatly enlarged detail of the picture motif of Fig. 21. Nonlinear primitives 8, 9 and 13 of different color are disposed in the form of a grid with constant grid spac-ings x and y. One primitive 8, 9 and 13 in each case fonns a color primitive 52 which is disposed in a grid cell 12 of the grid. Each color primitive 52 corresponds to ex-actly one pixel of a colored picture motif, e.g. the motif shown in Fig. 21.
Each pixel of the picture motif has a certain color component of a color system associated therewith. In the present case, the primary color system CMY is used.
Accordingly, the primitives 8, 9 and 13 of each color primitive 52 of the coating 7 have the colors cyan, magenta and yellow. The color component of a pixel is determined via the size of the colored areas of the primitives 8, 9 and 13. Due to its limited resolution, the human eye cannot perceive the primitives separately from each other and thus recog-nizes in a top view of the coating 7 only the secondary color of each color primitive 52, defined by the color areas of the primitives. It should be noted that in the case of incomplete coverage of the base surface, the color of the base surface yields an addi-tional color component, but if a white base surface is selected this leads only to a brightening of the visually perceived secondary color of the color primitive 52. On the other hand, a color primitive 52 can readily also be so designed that it substan-tially completely covers the area of a grid cell 12, so that solely the secondary color of the color primitive 52 defines the color of a pixel of the picture motif.

[0089) As shown in Fig. 23, the size of the colored area of a primitive is varied in such a way that the color component of each color primitive 52 is exactly detennined.

Therefore, in a top view of the coating 7 a picture motif to be represented results in an exactly defined color for each single pixel.

100901 The interaction of such a coating with linear embossed elements leads to an inventive optically variable structure as rendered in Fig. 24. The embossed structure 4 comprises linear embossed elements 5 and 15, the former being disposed along the preferred direction 16 and the latter along the preferred direction 17. The grid spacing x and y of the linear embossed grids 5 and 15 corresponds exactly to the grid spacings x and y of the coating 7. Fig. 24 indicates that the arrangement of the embossed ele-ments in the area of the coating 7 virtually does not change the visual impression in a top view. That is, due to the limited resolution of the human eye, only the secondary color associated with a color primitive 52 is perceived in the area of a grid cell 12 of the coating. Upon viewing from an angle other than the top-view angle, e.g.
from the direction 17, however, a completely different picture is perceived by the viewer. For exainple, only the color area of the primitive 8 is located on the flank 5a of the em-bossed element 5, while the color areas of the primitives 9 and 13 come to lie on the flank 5b. Accordingly, a secondary color defined by the color areas of the primitives 9 and 13 and the color of the base surface results for the flank 5b within the grid cell 12 of the embossed element 5, while the perceptible color for the flank 5a within the same grid cell 12 results from the inherent color of the primitive 8 and the color of the base surface. The same applies to each grid cell 12 of the coating 7 that is provided with an embossed structure. In this way it is possible to represent picture motifs in true colors and simultaneously provide the motifs with an impressive color shift ef-fect.

Example 7 (Figs. 27 to 29) [0091] Figures 27 to 29 show a further variant of an inventive optically variable structure wherein tilt effects, and secondary color effects produced by the overlapping of primitives, are combined with each other. Fig. 27 shows an embossed structure 4 with linear embossed elements 15. Unlike the embossed structure shown in Fig.
12, the embossed elements 5 and 15 of Fig. 27 have the cross sections shown in Fig. 34g and 34f, respectively.

[0092] Fig. 28 shows an inventive coating 7 which is coinbined with the embossed structure 4 from Fig. 27 to form an optically variable structure. The coating 7 is formed from three types of nonlinear primitives 8, 9 and 13 which are in each case disposed in the form of a regular grid. In accordance with the grids formed by the primitives 8 and 9, primitives with a filling and thus a large area coverage of the grid are particularly well suited for this coating variant. Furthermore, it is fundamentally also possible to use other primitives, such as the alphanumeric characters 13.
It is evi-dent from Fig. 28 that the arrangement of the primitives and thus of the grids defines the preferred directions 16 and 17. Also, the coating grid 7 has a grid spacing x in direction 17 and a grid spacing y in direction 16, which corresponds to the grid spac-ings of the embossed structure 4 from Fig. 27. The primitives of a grid have a certain color, e.g. the colors red, green and blue of the RGB primary color system. In the ar-eas defined by the arrangement of the grid, the primitives of the different-colored grids overlap and form a defined secondary color in said areas. The coating 7 thus appears in a top view as an overlapping of different-colored grids which have a sec-ondary color in the overlap areas. The arrangement of the overlap areas corresponds to the pixels of a picture motif or a geometric pattern, so that in a top view the picture motif or pattern can be recognized in a grid comprising primary colors corresponding to the secondary colors. In combination with the embossed structure from Fig.
27 the result is an optically variable structure displaying the above-described coating in a top view and the color structures dependent on the embossed structure 4 from other view-ing directions.

[0093] Figures 29a to 29c show further inventive coating grids 7. For reasons of clarity, the nonlinear primitives forming a grid are not shown singly, although they are spaced apart in a grid in the same way as in Fig. 28. As is evident from Fig. 29a, the grids formed from the primitives do not cross at right angles, so that three pre-ferred directions 17, 37 and 47 result for one possible arrangement of the embossed structure. The arrangement of the grids in turn yields overlap areas of the primitives of different grids, so that the coating 7 yields in a top view a complicated structure comprising pixels with secondary colors and the pure colors of the primitives.
The arrangement of the grids is effected so precisely on the base surface that the arrange-ment of the secondary color areas constitutes per se a security feature which is com-bined with the tilt effect caused by the embossed structure.

[0094] Fig. 29b shows the coating grid 7 from Fig. 29a in a variant. A
colorless area 39 has been inserted around the grid formed by the primitives 9. This results in a dependence of the arrangement of the primitives 13 on the white areas 39 and the primitives 9. The resulting spatial dependence of the primitives 9 on primitives of other grids and the inserted areas 39 yields an additional security feature of the coat-ing 7.

[0095] Fig. 29c shows a further variant of a coating grid 7 with secondary color ef-fects. In this case, an area 38 has been inserted around the grid formed from the primitives 8, leading to a subdivision of the grids formed from the primitives 9 and 13. The spatial dependence of the primitives on the primitives of other grids is an ad-ditional security feature that cannot be readily imitated at present. In addition, coating 7 of Fig. 29c yields overlap areas with secondary colors which lead to viewing direc-tion-dependent tilt effects by arrangement of an embossed structure.

Example 8 (Figures 30 to 34) [0096] The inventive coating 7 shown in Fig. 30 consists of elliptical primitives 8, 9 and 13 of different color. Unlike the hitherto described coatings 7, a direction 47 is marked that does not correspond to a preferred direction of the coating grid.
If the arrangement of the linear embossed elements is effected along said direction, a tilt effect results from viewing directions that do not match the preferred directions of the coating grid. If the coating 7 with an embossed structure disposed in direction 47 is integrated into a further coating 7 wherein the embossing is effected along one of the preferred directions of the coating 7, the depicted area of Fig. 30 constitutes addi-tional information within the total coating.

100971 Figures 31, 32 show cross sections of embossed structures in which addi-tional information 40 is contained. In the case of the structure shown in Fig.
31, the additional information 40 is produced by a change of the grid spacing of the em-bossed grid. However, the additional information in the embossed structure of Fig. 32 results from a change of the cross section of the linear embossed elements from circu-lar to triangular. [0098] The additional information of the coating can also be easily disposed in an embossed structure formed therefor, as is evident from the example of the structure of Fig. 33. The embossed structure comprising a triangular cross section has amplitudes 20 and a comparatively large grid spacing, leaving between the single linear em-bossed elements base areas 31 that can be provided with the additional infonnation of the coating. The additional information incorporated there is visible in a top view and from certain viewing directions and shows a tilt effect inherent in the inventive opti-cally variable structure.

100991 Fig. 34 shows different cross sections of linear embossed elements. It should be noted that cross sections involving a combination of the shown cross sec-tions are also possible. Also, the flanks of the cross section, e.g. those of Fig. 34m, can be concave.

Example 9 (Figures 35a, 35b, 36a and 36b) [0100] The production of an inventive data carrier is explained in Figures 35a, 35b and 36a, 36b.

[0101] The optically variable element is preferably produced by printing technol-ogy. For this purpose, the coating is printed on'a substrate, preferably the document material, by any printing process, preferably offset printing, and said coating is then embossed accordingly with an embossing tool. The embossing tool preferably used is an intaglio printing plate. This procedure is shown in Figures 35a and 35b.

[0102] Fig. 35a shows an inventive data carrier in cross section before the emboss-ing process. The data carrier substrate 10 is first printed e.g. all over with a base sur-face layer 29. The coating comprising primitives 26, 27 is applied thereabove.

[0103] The base surface layer 29 can also be present in the form of infonnation and patterns. It is also possible to use special printing inks which further increase the anti-forgery effect of the optically variable element. These may be optically variable print-ing inks, such as printing inks containing interference layer pigments or liquid crystal pigments, or metallic effect inks, such as gold or silver effect inks.

[0104] Fig. 35b shows a sectional view of the data carrier after embossing, which has been done in the shown example as a blind embossing by intaglio printing.
The embossing is so positioned that the coating with primitives 26, 27 comes to lie on the flanks of the embossed structure. Alternatively, the base surface 29 can also be ap-plied by another method, for example a transfer method, all over or likewise provided with gaps or a pattern. It is also possible to apply metallic pattern elements or coat-ings by the transfer method.

[01051 The base surface layer 29 can also be completely omitted, as shown in Fig.
36a. However, the embossing, which is produced for example by steel intaglio print-ing, is executed with ink.

[0106] Fig. 36a shows the structure before embossing with substrate 10 and coat-ing 26, 27. Fig. 36b shows the situation after embossing. The structure shown in Fig.
36b has been embossed with ink, so that an ink layer 30 is present congruently with the embossing. The additional ink layer 30 comes to lie as the uppermost layer, since this embossing has been carried out as the last method step here.

[0107] Preferably, an at least translucent ink is used for the ink layer 30.
The inta-glio printing with ink can, in a variation, be so executed that inking is effected only on the nonlinear embossed elements, while the valleys between the nonlinear em-bossed elements remain free of ink.

[0108] In a development, an ink with machine-readable additives, such as lumines-cent substances, can be used for the ink layer 30.

Claims

1. A security element with an optically variable structure having an embossed structure with linear embossed elements and a coating, the embossed structure and the coating being so disposed that at least parts of the coating are com-pletely visible upon perpendicular viewing but concealed upon oblique viewing, characterized in that substantially the total coating is formed from nonlinear primitives which are characterized by the parameters of outline form, size, color and orientation, and so combined with the embossed structure that different in-formation is visible upon a change of viewing direction.

2. The security element according to claim 1, characterized in that the nonlinear primitives have a circular, oval and/or polygonally bounded, in particular trian-gular, square or rectangular, outline form.

3. The security element according to claim 1, characterized in that the nonlinear primitives have an outline form determined by a symbol, geometric pattern and/or alphanumeric character.

4. The security element according to at least one of claims 1 to 3, characterized in that the nonlinear primitives have a substantially all-over filling.

5. The security element according to at least one of claims 1 to 4, characterized in that the nonlinear primitives have a dimension of 10 µm to 500 µm, in particular 20 µm to 250 µm.

6. The security element according to at least one of claims 1 to 5, characterized in that no dimension of a nonlinear primitive in any direction is more than four times the dimension in one of the other directions.

7. The security element according to at least one of claims 1 to 6, characterized in that the coating comprising nonlinear primitives is a printed layer, in particular an offset, intaglio, screen, flexographic, xerographic, ink jet or thermographic printed layer, or a layer incorporated by a laser printer or by the action of laser radiation.

8. The security element according to at least one of claims 1 to 7, characterized in that at least a part of the nonlinear primitives is disposed in a grid.

9. The security element according to at least one of claims 1 to 8, characterized in that groups of at least two nonlinear primitives of different color are disposed in the form of color primitives.

10. The security element according to claim 9, characterized in that at least a part of the color primitives is disposed in a grid.

11. The security element according to claim 8 or 10, characterized in that the grid of the primitives or the color primitives has a constant grid spacing.

12. The security element according to at least one of claims 9 to 11, characterized in that the nonlinear primitives and/or the nonlinear primitives of the color primi-tives have the colors of a primary color system.

13. The security element according to at least one of claims 9 to 12, characterized in that the optically variable structure has a multiplicity of color primitives which represent upon perpendicular viewing a multi-colored picture motif and/or geo-metric pattern whose visual impression varies upon a change of viewing angle.

14. The security element according to claim 13, characterized in that the color primitives correspond to pixels of the picture motif and/or geometric pattern, said pixels having certain color components of a color system associated therewith, and the color primitives have nonlinear primitives with colored areas in the colors of the color system, the size of the colored areas of the nonlinear primitives corresponding to the particular color component of the pixels, so that the color effect of the picture motif and/or the geometric pattern varies upon a change of viewing angle.

15. The security element according to claim 8 or 11, characterized in that at least two grids comprising nonlinear primitives of one color in each case form a pic-ture motif and/or geometric pattern, and nonlinear primitives of different grids are disposed overlappingly in areas defined by the arrangement of the grids and produce a secondary color in said areas.

16. The security element according to claim 15, characterized in that the areas of overlapping primitives correspond to pixels of the picture motif and/or geomet-ric pattern, said pixels having certain colors of a color system associated therewith, and the secondary color of the areas of overlapping primitives corre-sponds to the particular color of the pixels, so that the color effect of the picture motif and/or the geometric pattern varies upon a change of viewing angle.

17. The security element according to at least one of claims 8 to 16, characterized in that the arrangement of the nonlinear primitives and/or of the color primitives defines at least one preferred direction in the plane of the coating, and the linear embossed elements are disposed at least in certain areas in the direction of the at least one preferred direction, so that the visual impression varies dependently on viewing direction when the areas provided with embossed structure and coating are viewed perpendicular to the at least one preferred direction.

18. The security element according to at least one of claims 1 to 17, characterized in that the optically variable structure has additional information which arises by variation of the coating and/or the embossed structure.

19. The security element according to claim 18, characterized in that the additional information arises by a variation of the form, color and/or the arrangement of the nonlinear primitives, such as offset, change of grid spacing, omission, reflec-tion of single or several nonlinear primitives, or by arrangement of information individualizing the optically variable element, such as alphanumeric characters or bar codes.

20. The security element according to at least one of claims 1 to 19, characterized in that at least a part of the linear embossed elements forms an embossed grid with a grid spacing.

21. The security element according to claim 20, characterized in that the additional information arises by a variation of the form, size, height and/or the arrange-ment of the linear embossed elements, such as offset, change of grid spacing, omission of single or several linear embossed elements.

22. The security element according to at least one of claims 1 to 21, characterized in that the optically variable structure has a further ink layer which is preferably translucent and which is disposed congruently with the raised areas of the em-bossed structure.

23. The security element according to at least one of claims 1 to 22, characterized in that the optically variable structure has a metallic base surface layer.

24. The security element according to at least one of claims 1 to 23, characterized in that the coating and/or the further ink layer has machine readable properties at least in certain areas.

25. The security element according to at least one of claims 1 to 24, characterized in that the coating and/or the further ink layer has magnetic, electroconductive or luminescent properties.

26. The security element according to at least one of claims 1 to 25, characterized in that the optically variable structure is superimposed or underlaid with an addi-tional translucent, optically variable layer or a foil element.

27. The security element according to at least one of claims 1 to 26, characterized in that the optically variable structure is subdivided into partial areas in which dif-ferent partial embossed structures and/or partial coatings are disposed.

28. The security element according to claim 27, characterized in that the partial em-bossed structures or partial coatings are offset in at least two adjacent partial ar-eas by a fraction, in particular a third, of the grid spacing.

29. The security element according to either of claims 27 and 28, characterized in that at least the partial embossed structures of a partial area have an unembossed edge contour.

30. A data carrier having a security element according to any of claims 1 to 29.

31. The data carrier according to claim 30, characterized in that the data carrier is a paper of value, in particular a bank note.

32. Use of a security element according to any of claims 1 to 29 or of a data carrier according to claim 30 or 31 for product protection.

33. A method for producing a security element with an optically variable structure having an embossed structure with linear embossed elements and a coating, the embossed structure and the coating being so disposed that at least parts of the coating are completely visible upon perpendicular viewing but concealed upon oblique viewing, characterized in that a substrate is provided with nonlinear primitives which form substantially the total coating and which are character-ized by the parameters of outline form, size, color and orientation, and the nonlinear primitives are so combined with the embossed structure that different information is visible upon a change of viewing direction.

34. The method according to claim 33, characterized in that the nonlinear primitives are printed on the substrate and/or produced by the action of laser radiation.

35. The method according to claim 34, characterized in that the print is produced by planography, e.g. the offset process, by relief printing, e.g. letterpress or flex-ographic printing, by screen printing, by gravure printing, e.g. halftone gravure or intaglio printing, by an ink-jet or thermographic method, e.g.
thermotransfer, or by laser printing.

36. The method according to at least one of claims 33 to 35, characterized in that the print or the application of the nonlinear primitives to the substrate is effected before the production of the embossed structure.

37. The method according to at least one of claims 33 to 36, characterized in that the embossed structure is produced by intaglio printing.

38. The method according to claim 37, characterized in that simultaneously with the incorporation of the embossed structure, a further ink layer is printed on the sub-strate, being disposed congruently with the raised areas of the embossed struc-ture.