CA2627902A1 - Security element and method for the production thereof - Google Patents

Abstract

The invention relates to a method for producing a security element (12) with an optically variable structure, which contains an individualization feature, with the following method steps: a) providing a substrate with a marking structure with a number of flat markings (24, 26), and; b) providing the substrate with a relief structure having a number of raised relief elements (22). The marking structure and the relief structure are combined to enable different information to be viewed from different viewing directions, and the individualization feature is generated in at least one of the working steps a) or b) with a contactless method or with a printing method without a fixed printing form.

Description

Security Element and Method for Manufacturing the Same The present invention relates to a security element having an optically variable pattern that includes an individualizing mark, as well as a method for manufacturing such a security element. The present invention further relates to a data carrier equipped with such a security element.

To protect against reproduction, especially with color copiers or comparable reproduction methods, data carriers, such as banknotes, bonds, certificates, vouchers, checks, valuable admission tickets and other papers that are at risk of counterfeiting, such as credit cards, passports and other identification documents, as well as product protection elements, such as labels, seals and packaging are furnished with opticallv variable security elements. Here, the counterfeit protection is based primarily on the fact that the optically variable effects are visually easily and clearly perceptible for human viewers, but cannot be reproduced with currently known reproduction devices, since these always render the optically variable elements from only one viewing direction.

At the same time, such data carriers are often intended to include an individualization or personalization, such as numbering in banknotes or personal data or a photograph in identification documents. These individual components of the data carrier compete with other security elements for the space on the data carrier.

As optically variable security elements for data carriers are known, for example from publication EP 0 801 604 B1, relief patterns having a tilt effect.
These security elements consist substantially of an embossed grid of a certain spatial frequency that is combined with a flat coating grid of the same spatial frequency in such a way that at least portions of the coating grid are visible when viewed vertically, but are covered when viewed at an angle from a predetermined viewing direction. In this way, when viewed alternatingly vertically and at an angle, a tilt effect is created.

However, the standard printing and embossing method used for this do not permit individual pieces of information for each individual up in the tilt image. If, on the other hand, the standard method for individualizing banknotes or security prints that use numbering in letterpress or relief print, then a previouslv introduced embossing would be partially destroyed.

However, the printing sequence can be reversed only with difficulty, since the individualization is generally scheduled as the last print cycle.
Further, since the grid patterns are fine line or dot matrices, effect ink that, due to its pigment size, can be applied only in the relatively coarse screen printing cannot normally be used as a flat print.

A further disadvantage lies in the fact that the flat print and the corresponding relief pattern must be produced in two different operations, and register variations thus result that can cause the tilt effect to appear only weakly or not at all. Therefore, the tilt effect securitv elements are normally disposed on a data carrier multiply and slightly staggered to ensure that the tilt effect shows up well in at least one of the elements.

From publication DE 199 47 425 Al is known a method for coating existing relief patterns in which the relief-shaped material is coated with the aid of ink droplets or pigments, in each case from an oblique angle, so that the sides are each colored with a certain color. However, this method requires an oblique orientation of the ink droplet or pigment flow relative to the relief pattern, preferably in an evacuated or positive-pressure zone, which makes quick mass production with conventional printing machines difficult. The method does also facilitate later marking of the data carriers, but no individual marking.

Based on that, the object of the present invention is to specify a generic security element that avoids the disadvantages of the background art. In particular, the security element is intended to combine individualization and the optically variable effect in an advantageous manner and also permit their manufacture at the high processing speeds required in security printing.

This object is solved by the manufacturing method and the security element having the features of the independent claims. Developments of the present invention are the subject of the dependent claims.

According to the present invention, a method for manufacturing a security element having an optically variable pattern that includes an individualizing mark comprises the method steps:

a) providing a substrate with a marking pattern having a plurality of flat markings; and b) providing the substrate with a relief pattern having a plurality of raised relief elements.

Here, the marking pattern and the relief pattern are combined in such a way that different pieces of information are visible from different viewing directions, and the individualizing mark is produced in at least one of the work steps a) or b) with a non-impact method or a printing method without a fixed printing plate.

Printing methods without a fixed printing plate are also referred to as non-impact-printing methods or NIP methods. The name "non-impact" here is based on a differentiation from previously common "impact printers," in which a slug or needles put the information on the paper by impact. Such systems were frequently replaced by electrophotographic methods, in which the information is transferred contactlessly via a laser to an intermediate carrier, the latent charge image colored with a toner, and then transferred to the paper. Thus, also in the NIP methods, there is contact between the information color carriers and the paper when printing, but the information is not transferred by impact (see Handbuch der Printmedien (Handbook of Print Media), Ed.: Helmut Kipphan, Springer, 2000, p. 709). Printing methods without a fixed printing plate include especially electrophotography, ionography, magnetography, ink-jet methods and thermography (op. cit., p.
711).

In a first advantageous embodiment, the marking pattern and the relief pattern are produced with the same method in one work step. According to another, likewise advantageous embodiment, the marking pattern and the relief pattern are produced in separate work steps, wherein the marking pattern can be produced before or after the relief pattern.

All embodiments achieve, as advantages, a space-saving combination of the security element and the individualization of a data carrier, as well as additional security through the possibility of correspondence of the security element and other individualizations, such as the combination of a tilt element with numbering on a banknote.

If the flat markings are produced, for example, by laser ablation of ink from preprinted surfaces, for these, too, effect inks can be used that, due to their pigment size, can be applied only in screen printing with a relatively high screen aperture and thus, in printing, do not permit fine resolution in the necessary spatial frequency. In this way, for example color and information tilt effects can be combined.

Especially when the flat markings and the relief elements of the relief pattern are laid out in grids of the same spatial frequency, it is not necessary to maintain an oblique angle between the two production steps.

Through the production of the relief substantially in the substrate of the data carrier, also the problem of the abrasion of ink layers upon use is prevented, as can occur, for example, in the method known from publication DE 692 09 185 T2. Since the relief is located substantially in the substrate, it exhibits improved durability against other mechanical or chemical stresses, as well.

Furthermore, if the marking pattern and the relief pattern are produced with the same device in one operation, there is no registration problem bet'ATeen the relief information and the marking information. In this way, multiple depiction of the created tilt information can be omitted.

The substrate of the data carrier is especially a coated or uncoated cotton paper or a coated or uncoated plastic foil, especially based on PVC, polycarbonate or PET.

According to a preferred embodiment of the method, the relief pattern is embossed in the substrate. The embossing can occur, for example, with an embossing die or also in intaglio printing. According to another, likewise preferred embodiment, the substrate is provided with the relief pattern by the action of a laser beam. Here, the laser parameters for producing the relief pattern are tuned in a per se known manner to the composition and properties of the substrate, as described in publications DE 102 47 591 Al and DE 3213 315 Al, whose disclosure in this respect is incorporated in the present application.

The relief pattern is advantageously developed in the form of a grid, preferably a grid having a constant spatial frequency. Here, the raised grid elements form the "grid points" of the grid. It is understood that the term "grid point" is understood in the standard printing technology sense and does not mean a dimensionless point in the mathematical sense. Possible grid arrangements comprise grids having a constant period (constant point size, constant point spacing), amplitude-modulated grids (variable point size, constant point spacing), frequency-modulated grids (constant point size, variable point spacing) and higher-order non-periodical grids, as described in the above-mentioned Handbuch der Printmedien on pages 44 ff. In addition to two-dimensional grids, also one-dimensional grids (line grids) may be used. In this case, the "grid points" are formed by line-shaped grid elements.

In an advantageous variant of the present invention, the substrate is provided with the marking pattern by the action of a laser beam. Here, the marking pattern can be introduced into a substrate body, such as a cotton paper or a plastic foil, or into a layer applied on the substrate body.
According to another, likewise advantageous variant of the present invention, the marking pattern is imprinted on the substrate. For example, the marking pattern can be applied in the ink-jet method or with a digital printing method that works with low pressure. In other embodiments, the marking pattern is advantageously produced in planographic printing, such as in the offset method, in relief printing, such as in letterpress printing or in the flexographic printing method, in screen printing or in a thermographic method, such as in the thermotransfer method.

Like the relief pattern, also the marking pattern is advantageously developed in the form of a grid, preferably in the form of a grid having a constant spatial frequency, the flat markings forming the "grid points" of the grid.

Here, the possible grid arrangements are the same as described above in connection with the relief grids.

The grid of the relief pattern and the marking pattern preferably exhibit the same spatial frequency. However, it is also possible to form the relief pattern and the marking pattem having slightly different spatial frequencies to produce beat or Moire effects.

The individualizing mark preferably comprises letters, numerals or a symbol code, such as a barcode or matrix code.

The substrate and/or the surface of the security element can include further security substances that are activated, exposed, covered, partially destroyed or removed in at least one of the work steps a) or b).

The present invention also comprises a security element having an optically variable pattern that includes a marking pattern having a plurality of flat markings and a relief pattern having a plurality of raised relief elements, the marking pattern and the relief pattern being combined in such a way that different pieces of information are visible from different viewing directions.

Here, the marking pattern and/or the relief pattern is provided with an individualizing mark that is produced with a non-impact method or a printing method without a fixed printing plate.

The relief elements of the relief pattern and/or the flat markings of the marking pattern are advantageously disposed in the form of a grid, preferably in the form of a grid having a constant spatial frequency. As mentioned above, the grids of the relief pattern and the marking pattern can exhibit the same spatial frequency or, to produce beat or Moire effects, slightly different spatial frequencies.

The flat markings are expediently disposed at least in part on sides of the relief elements, a relief element and a flat marking disposed on at least one of its sides together forming a pattern element. The flat markings advantageously exhibit at least one colored area. It will often be useful to form the flat markings having multiple colored areas that are disposed at least in part on different sides of the relief elements such that the viewer gains different color impressions from different viewing directions.

In an advantageous development of the present invention, the optically variable pattern includes a plurality of pattern elements (in other words, relief elements having flat markings disposed on at least one of their sides) that depict a multicolored image motif whose visual impression varies when the viewing angle is changed.

Here, the individualizing mark can comprise letters, numerals or a symbol code, such as a barcode or matrix code. It can also exhibit multiple components that are perceptible only from different viewing angles. For example, the individualizing mark can depict a numeral that, depending on the viewing angles, appears in another color, or it can include two or more different symbols that are each perceptible from a different direction.

The relief pattern and the marking pattern can be disposed on a single- or multi-layered substrate, or on a substrate that is single- or multi-layer coated, printed, pasted, clad or laminated.

The substrate and/or the surface of the security element can also exhibit further, especially machine-readable security features to further increase the counterfeit security.

In a further development of the present invention, the marking pattern and the relief pattern are combined with one or more further layers that depict a pattern or image that is visually perceptible when viewed vertically.

The raised relief elements of the relief pattern can advantageously also be formed to be tactilely perceptible. The height of said tangible marking above the surface can be varied within a broad scope through the choice of laser parameters, the substrate material and the relative speed of the laser beam and the substrate at laser inscription. Typically, a height between 30 m and about 100 m is chosen.

The relief pattern can especially include a plurality of non-line-shaped relief elements, at least a portion of the non-line-shaped relief elements advantageously exhibiting substantially the shape of a tetrahedron, a spherical segment, a pyramidal frustum, a conical frustum, a cylindrical segment, a torus segment, an oval, a teardrop or a pyramid.

To compensate for register variations, the relief pattern can be subdivided into sub-regions in which different partial relief patterns are disposed. In particular, the partial relief patterns can each form a grid of the same line screen and, in at least two adjoining sub-regions, the grids of the partial relief patterns can be disposed offset by a fraction of the line screen, especially by about one-third of the line screen.

The present invention also includes a data carrier, especially a value document, such as a banknote, identification card or the like, having a securitv element of the kind described above.

Further exemplary embodiments and advantages of the present invention are described below with reference to the drawings. To improve clarity, a depiction to scale and proportion was dispensed with in the drawings.

Shown are:

Fig. 1 a schematic diagram of a banknote having a security element according to an exemplary embodiment of the present invention, Fig. 2 a section along the line II-II in fig. 1, Fig. 3 a section of only the relief pattern of the security element in fig.
1, in plan view, Fig. 4 a section of only the marking pattern of the security element in fig. 1, in plan view, Fig. 5 the combination of the relief pattern in fig. 3 and the marking pattern in fig. 4, Fig. 6 a top view of a security element according to an exemplary embodiment of the present invention, diagrammed schematically, Fig. 7 a diagram as in fig. 5 for a security element according to a further exemplary embodiment of the present invention, Fig. 8 a section of only the marking pattern of a security element according to a further exemplary embodiment of the present invention, in plan view, Fig. 9 a section of only the relief pattern of the security element in fig.
8, Fig. 10 the combination of the marking pattern in fig. 8 and the relief pattern in fig. 9, Fig. 11 in (a) and (b) schematic top views of the basic grid of security elements according to further exemplary embodiments of the present invention, Fig. 12 a schematic top view of the basic grid of a further security element according to the present invention, Fig. 13 a security element according to yet a further exemplary embodiment of the present invention, wherein (a) shows the image impression when viewed vertically (b), and (c) depicts the image impression when viewed from an oblique angle (d), and Fig. 14 a further development of the security element in fig. 12.

The invention wiIl now be explained using a banknote as an example. For this, fig. 1 shows a banknote 10 having an inventive security element 12 that is disposed in the image region 14 of the banknote. The security element 12 includes an optically variable pattern that, from different viewing directions, presents different pieces of information to the viewer and thus displays a tilt effect. Such securitv elements are often used in banknotes and other value documents with cash value, since the tilt effect can easily be visually perceived and checked by the viewer, and yet, particularh, due to the direction dependency of the visual impression, it cannot be reproduced with today's copying devices, which render the optically variable pattern only from one viewing direction.

Furthermore, the optically variable pattern of the security element 12 exhibits an individualizing mark that is characteristic for the individual data carrier.
For banknotes, this can be, for example, the entire serial number or a part of it, and for identification documents, the individualization can include personal data or a portrait. To be able to integrate this individualizing mark into the optically variable pattern, it is produced, as explained in detail below, with a non-impact method or a printing method without a fixed printing plate in at least one of the work steps for producing the optically variable pattern.

First, the fundamental structure of the optically variable pattern of the security element 12 is explained in greater detail with reference to figures 2 to 5, with fig. 2 showing a schematic sectional view along line II-II in fig.
1.
Fig. 3 shows a section of only the relief pattern of the security element 12, in plan view, fig. 4 a section of only the marking pattern of the security element 12, in plan view, and fig. 5 shows the combination of the relief pattern in fig.
3 with the marking pattern in fig. 4.

As can best be seen in the diagram in fig. 2, the optically variable pattern exhibits a plurality of raised relief elements 22 that can be produced, for example, by embossing the banknote 10. If the banknote is mechanically deformed with an embossing die, then the bottom of the banknote displays corresponding negative deformations that, however, are not significant in the context of the present invention and are thus not depicted in the figures. If the relief elements are produced in another manner, for example by the action of a laser beam on the substrate material, then normallv no corresponding deformations are created on the reverse of the banknote.

The optically variable pattern 20 further includes a marking pattern having a plurality of flat markings 24, 26 that are disposed on different sides of the relief elements 22 and thus lend the securitST element a different appearance depending on the viewing direction.

For illustration, figures 3 and 4 show a section of the relief pattern and of the marking pattern, in plan view, wherein the square grid drawn in with dotted lines serves merely to improve the diagram clarity. Both the relief elements 22 and the flat markings 24, 26 are disposed in a grid having a constant spatial frequency and whose horizontal and vertical line screen are given by the values x and y. In the exemplary embodiment, a square grid is depicted with x = y.

As can be seen in fig. 4, the spatial frequency of the marking pattern is based on an imaginary reference point 28 in the center of each grid square. The flat markings 24, 26 themselves can take on different positions within the grid squares to come to lie on different sides of the relief elements. If, for example, the marking pattern in fig. 4 is combined with the relief pattern in fig. 3, then the flat markings 24 and 26 come to lie on opposing sides of the relief elements 22, as shown in figures 2 and 5. In each case, one relief element 22 forms, together with the flat marking 24 or 26 disposed on one of its sides, a pattern element 32, wherein the pattern elements 32, as the smallest units, form the pixels of the screened information collectively depicted by the optically variable pattern.

When viewed from a first viewing direction 30 (fig. 2), primarily the markings 24 determine the image impression, while the markings 26 are hardly visible or not at all. In contrast, when the pattern is viewed from an opposing viewing direction, primarily the markings 26 determine the image impression, while the markings 24 contribute hardly or not at all. In this way, through suitable arrangement of the markings 24 and 26, an individualizing mark having a tilt effect can be integrated into the optically variable pattern 20 of the security element 12.

Some specific exemplary embodiments are described below, where, with reference to figures 2 to 10, embodiments in which the relief pattern and the marking pattern are produced in separate work steps are described first.

In a first exemplary embodiment that will now be explained in greater detail, especially with reference to the depiction in figures 2 and 6, the individual piece of information is introduced, by color change or ink removal, into relief patterns that were embossed, with or without areal ink layers, in substrates.
For this, on a substrate 40 is first imprinted a laser-absorbing, for example black, ink layer 42 that, in a later work step, can be locally ablated or modified by the action of laser radiation such that a local color change is created at the site of the laser impingement.

Then, relief patterns are embossed in the printed substrate, in the exemplary embodiment in the form of a regular knob relief 22, as shown in figures 2 and 3. Then, to produce the flat markings, the printed and embossed substrate is impinged on with laser radiation in accordance with a predefined dot matrix template, the reference points of the dot matrix template exhibiting the same line screens x and y as the knob relief 22.

In the simplest case, due to the laser impingement, the black ink layer 42 is ablated locally such that the white background layer of the substrate stands out at the labeled sites 22, 24, as shown in fig. 2. Under the laser-absorbing ink layer 42 can also be disposed a different colored, non-absorbing ink layer can that is locally exposed by the laser impingement. In further embodiments, through the laser radiation, a local color change in the ink layer 42 can be induced also without ablation. For example, the ink layer can exhibit an ink mixture having a laser-radiation-absorbing mixture component and a laser-radiation-transparent mixture component, and, by the action of the laser radiation, the absorbing mixture component is bleached, evaporated or altered in its reflection properties, or through a chemical reaction, transformed into a material having other optical properties, such that visually perceptible flat markings are created.

It is understood that, to be able to depict a piece of information, the flat markings of the dot matrix template are not all disposed at the reference point. Rather, as shown in fig. 6, a first sub-group 46 of the flat markings is shifted (+x/4, +y/4) from the reference point, or to the top right, while a second sub-group 48 of the flat markings is shifted (-x/4, -y/4) from the reference point, or to the bottom left. The first and second sub-group of flat markings thus come to lie on opposing sides of the relief elements 22. For the sake of clearer illustration, in fig. 6, the relief elements 22 printed on with the black ink layer 42 are depicted as unfilled, while the flat markings 22, 24 in which the ink coating is ablated and that thus appear light for the viewer are depicted as filled in the schematic diagram in fig. 6.

The first and second sub-group of flat markings 46, 48 together form the piece of information that is inscribed as an individual mark in the optically variable pattern by lasering. In the exemplary embodiment in fig. 6, the two sub-groups 46, 48 together form the numeral "5". When viewed from direction 50, the viewer looks primarily at the light markings 26 of the first sub-group 46, while the markings 24 of the second sub-group 48 lie on the side of the relief elements 22 facing away from the viewer. Thus, from this direction, the numeral "5" appears dark against a light background.

In contrast, when viewed from direction 52, the viewer looks at the light markings 24 of the second sub-group 48, while the markings 26 of the first sub-group 46 on the side of the relief elements 22 facing away from the viewer lie such that, from direction 52, the numeral "5" appears light against a dark background. This change in contrast appears conspicuously when the security element is tilted. It is understood that, depending on the form of the relief elements 22 and the relative arrangement of the markings 24, 26 to the reference point 28, also other excellent viewing directions can be chosen.

Since, in printing machine registration, it must be expected that the lasered markings 24, 26 can also land on the center of the knobs 22 and in the valley between the knobs 22 and thus no easily visible tilt effect is created, multiple homogeneous fields having relief patterns can be laid out in which the lasered dot matrix is shifted in each case by, for example, 1/3 of the line screens. In precisely this way, also the pre-embossed knob grid could exhibit these shifts in different fields.

The application of the flat marking 24, 26 to the right site can be supported in that the substrate 40 is coated appropriately for the relief pattern 22 such that, for example, certain sites take on color and others do not. If the marking is executed with the aid of laser markers, the coating can advantageously be applied in such a way that certain sites absorb laser radiation given a certain set of parameters (for example, comprising energy and/or wavelength and/or pulse length) and thus undergo a color change, but other sites only given another set of parameters.

Potential registration problems can also be reduced in that the position of the predefined grid is established through suitable metrological measures. For this, for example, together with the operation creating the relief, registration marks can be introduced that are subsequently read out by suitable sensors prior to the application of the flat markings 24, 26, or industrial image processing can be used to establish the position of the predefined relief 22.
Since non-impact and/or digital printing methods can work without a fixed template, not onlv the content but also the position of the flat marking can be defined shortly before the application and thus be adjusted to the actual position of the relief.

In precisely this way, the piece of information to be applied can be based on data that is read from the substrate 40 only during its transport, and then applied corresponding to this piece of information. In this way, for example, the serial number of a banknote can be scanned prior to lasering and then the final number lasered into the knobs 22 as a piece of information. The same applies, for example, to personalization data on identification documents that are first scanned and then e.g. partially incorporated in a tilt image.

The piece of information can also be created in that the lasered points exhibit different sizes or shapes or are concentrated to form lines. For example, it can be created by removing the ink, lightening the color or changing the color impression, all of these variants being subsumed under the term "color change" in the present description.

Also the ink-jet method or another digital printing method that works with such low pressure that the relief patterns are not destroyed can take the place of the lasering. This normally produces dark structures on a light substrate having embossing.

The sequence of the work steps can also be reversed. However, the described sequence is typically preferred, since then the individualization occurs as the last print cycle.

The relief elements 22 can also be provided with markings 24, 26 at two or more different sites, as shown in the exemplary embodiment in fig. 7. In this case, different images are created depending on the viewing angle. For example, a first symbol, such as a numeral, can be composed of marking points 24 that appear at the bottom left on the relief elements 22. A second symbol, such as a letter, is composed of marking points 26 that appear at the top right on the relief elements 22. Depending on the viewing angle, the first or second symbol is then perceived.

The procedure for a line relief, in other word, a relief pattern having line-shaped relief elements, is similar: In the preprinted ink is embossed a line pattern that exhibits parallel sides that point in opposite directions. The flat markings are then introduced in such a way that lines are created that land on the sides. Different pieces of information can be depicted, for example, in that the line grid is shifted by half the spacing of the pre-embossed relief grid.

The preprinted ink can also be executed as a screen printing ink that includes feature or effect pigments. For the present embodiment, all that matters is that this ink permits processing with the aid of the laser. In this,,A,ay, the resolution required for tilt elements can be achieved, also when molds with a large screen aperture must be used for printing to accommodate the larger pigment size.

Another possibility to introduce the individual piece of information into the optically variable pattern consists in contactlessly introducing the relief patterns into substrates already provided with flat markings, as now described with reference to figures 8 to 10.

In these embodiments, a substrate is first provided, in regular intervals of a certain spatial frequency, with flat markings, for example, in the form of different colored circles 60, as shown in fig. 8. All conventional printing methods of suitable resolution can be used for this.

Then, a relief pattern having raised relief elements 62, 64 is produced in the substrate by impingement with laser radiation, as depicted in fig. 9. In the exemplary embodiment, the line screens x, y of the relief pattern are chosen to be identical to the line screens x, y of the marking pattern. Here, the laser parameters for producing the relief pattern are coordinated with the composition and the properties of the substrate, with reference being made to publications DE 102 47 591 Al and DE 32 13 315 Al for details of the per se known method. Furthermore, the laser parameters and the properties of the printing inks used for the flat markings are coordinated with each other in such a way that the printing inks used absorb the laser radiation only slightly or not at all such that they are altered or removed by the laser radiation only slightly or not at all.

To be able to depict the piece of information, in this exemplary embodiment, the relief pattern includes a first and second sub-group of relief elements 62 and 64 that are staggered by half a line screen. Depending on which of the colored circles 601and where on the relief elements 62, 64, different color impressions result for the viewer from different viewing directions, as illustrated with reference to fig. 10. Similar to the situation for the exemplary embodiment in figures 3 to 5, the two sub-groups of the relief elements 62, 64 can depict the shape of the desired individualizing marks, for example a numeral, a letter or another symbol. The sections in figures 8 to 10 show, for example, a portion of an optically color-variable depiction of a numeral "5".
It also applies to this embodiment that, for normal registration with the aid of a printing machine, it must be expected that the printed dots 60 can also land on the center of the knobs 64, 66 and in the valley between the knobs and thus no easily visible tilt effect is created. Therefore, multiple identical or similar fields can be laid out in which the lasered knob grid is shifted in different directions in each case, for example by 1/3 of the line screens. In precisely this way, also the preprinted dot matrix 60 could exhibit these shifts in different fields.

The inscribed individual piece of information can also be created in that the lasered knobs exhibit, for example, different sizes or shapes or e.g. are concentrated to form lines or "worms". The preprinted dots 60 can also be provided with knobs at two or more different sites such that, depending on the viewing angle, different images are created. In this way, e.g. a number can be composed of knobs that appear at the bottom left under the dots, and a further one of knobs that appear at the top right. Depending on the viewing angle, one or the other number is then perceived.

The procedure for a line relief is again similar: Here, into the preprinted lines is tactilely introduced a line pattern that exhibits parallel sides that point in opposite directions. The flat markings then lie on the sides of this relief.

Different pieces of information are depicted in that the relief is shifted e.g. by half the spacing of the preprinted line grid.

In further embodiments of the present invention, the individual piece of information can also be produced in the form of a color or relief change in already existing tilt images.Here, a conventional tilt image is first manufactured according to the background art, and the individualizing mark is then produced by a non-impact and/or a digital method in the form of an information-bearing marking pattern (as for instance in fig. 2 to 7) or in the form of an information-bearing relief pattern (as for instance in fig. 8 to 10).

In this way, an additional piece of information that produces its own tilt effect is created within the predefined tilt image.

In principle, here, too, the inscribed, especially lasered-in piece of information can be created by color change (ink removal, lightening or a change in the color impression). The piece of information can also be created in that other shapes than dots or lines are lasered, or different sizes or line widths are used.

A variant of the present invention is created when, prior to the information-carrying print cycles, one or more further layers are preprinted. Then, this laver can either be changed and, in doing so, layers lying on top influenced as well, or it can be exposed, depending on which of the layers is absorbent.
If there are further layers underneath, they can be exposed. One of the layers can also include a feature ink that can be seen or detected only with technical aids and is influenced or exposed bv the lasering.

In the further exemplary embodiments now described with reference to figures 11 to 14, the relief pattern and the marking pattern are produced with the aid of the same non-impact method, especially by means of laser impingement, such that registration problems are inherently avoided. Here, the individual piece of information can be depicted by the relief pattern or the marking pattern.

In first exemplary embodiments of this variant of the present invention, a relief pattern is produced in each substrate by impingement of coated substrates. Here, the coating is chosen such that a color change (ink removal, lightening, bleaching) can be produced by the laser radiation in the same operation.

The relief patterns can be introduced into the coated substrate first, and then the flat markings, or conversely, depending on what seems to be advantageous in terms of method. It will most often be useful to introduce the flat markings first. Here, the arrangement of the two components on the tilt image being created can match the above-described figures and examples such that the flat markings consist of dots that appear on the sides of relief-forming knobs.

The information content can be either in the arrangement of the flat markings or in the arrangement of the relief elements. It is possible also in this variant of the present invention to make different pieces of information visible from different viewing angles in that, for each different piece of information, the flat markings come to lie on different sites of the relief. Also effect inks can be used as the background.

Here, the basic grid can be oriented horizontally and vertically, as shown in fig. 11(a), in which the reference number 70 indicates the relief elements, and the reference number 72, the flat markings. Here, the line screen can be, for example, x = y = 0.5 mm. For the embodiments in fig. 11(a), the pattern must be tilted diagonally in order to view the different states, as indicated by the arrows 74. Should the pattern be able to be tilted vertically from top to bottom, as perhaps automatically executed by the viewer, it is advantageous to dispose the basic grid rotated 45 , as depicted in fig. 11(b). The arrangement of the piece of information diagonally has the advantage that more space is available for the piece of information that is to be depicted.

Of course other regular arrangements of the relief elements 70 or the flat markings 72 are also possible, especially those in which the grid is stretched or compressed in one of the two main directions.

It can also be advantageous to introduce into the preprinted background, through fine patterns or slightly different colors, a graphic, an image or a pattern that is visible in plan view and diverts the eye of the viewer from the information hidden in the tilt image. Only when tilted is the introduced individualization information then conspicuous.

Since the production of the relief elements by means of laser entails a removal of the ink, the relief element enlarges the lightened site in each case.
Auxiliary substances that support relief formation can also be used in the substrate; in this case, a lower energy will be able to be used for this that leads to less extensive ink ablation such that the area used for the flat marking receives a larger share of the total ink ablation and the information included in the flat marking is more easilv visible.

The height, the expanse and the brightness of the relief elements 70 and the expanse and the brightness of the flat markings 72 can also be varied in such a way that a grid image is created in the manner of an autotypical grid (i.e.
identical spacing of grid points, with different point sizes). In this way, the viewer will perceive only the grid image in plan view, while a further piece of information is displayed when tilted.

Also in a further exemplary embodiment, explained with reference to fig. 12, it can be achieved that, in plan view, the inscribed individual piece of information initially appears to be hardly or not at all visible. For this, the laser parameters are chosen such that the relief pattern 70 and the flat marking pattern in the coated substrate exhibit the same or at least a similar gray value. Then, in certain regions 76, the arrangement of the relief elements 70 and the flat markings 72 are interchanged. At an oblique viewing angle, pieces of information can then be perceived that, depending on the viewing and light incidence angle, appear light on a dark background or dark on a light background.

The two last-mentioned approaches can also be combined with one another, as now explained with reference to fig. 13. In the portrait 80 shown there, the relief elements and the flat markings are each disposed in a constant grid.

The different brightness impression is created merely through a variation of the height, expanse and brightness of the relief elements and of the expanse and brightness of the flat markings. In region 82, whose contour constitutes an individual piece of information, in the exemplary embodiment the numeral "5", the arrangement of the relief elements and the flat markings is interchanged, as shown in fig. 12.

When the portrait 80 is viewed from the vertical viewing direction 84 (fig.
13(b)), this interchange is not perceptible since, from this viewing direction, the interchanged and non-interchanged arrangements produce the same brightness impression. The image impression thus corresponds to the diagram in fig. 13(a). If, in contrast, the portrait 80 is tilted and viewed from an oblique angle 86 (fig. 13(d)) then, depending on the viewing direction, the region 82 stands out, light or dark, from its surroundings and the inscribed individual information is perceptible, as schematically depicted in fig.
13(c).
The described embodiments can be extended in such a way that the optically variable pattern includes additional pieces of information that are perceptible, for example, in the horizontal tilt direction. Fig. 14 shows an extension of the exemplary embodiment in fig. 12, in other words a relief pattern having relief elements 70 and a marking pattern having flat markings 72, the arrangement of the relief elements 70 and the flat markings 72 being interchanged in certain regions 76. In the exemplary embodiment in fig. 14 are provided, perpendicular to the connecting line of the relief elements and the flat markings, additional markings 78 that can include a further piece of information.

This further piece of information lies outside the sides of the relief elements 70 and is thus already easily perceptible when viewed vertically. The further piece of information can thus be used to depict image contents, primarily in plan view, that initially divert the eye of the viewer from the actual tilt information.
In other exemplary embodiments, the additional markings 78 can also be applied only at certain sites or be reinforced at certain sites. It is also possible to dispose the additional markings 78 and the tilt image 70, 72 in such a way that they complement each other.

The additional markings 78 can also be used to lighten the overall appearance of a security element or to further adapt the gray values of the flat markings and the relief elements to each other. For this, the size and the ink ablation of these additional markings can be adjusted accordingly.

The contrast created upon tilting can be improved if the areal fraction of the light markings (flat and relief) is adjusted to the brightness impression of the total area. For a technical description and comparison measurement, the brightness is described in gray levels. Thus, the so-called simple contrast is formed from the ratio of the gray level of the light points (Gh) to the mean gray level of the total area (Gm):

K = Gh/Gm=

As is immediately evident, this ratio becomes that much better the darker the overall impression of the area and thus the smaller Gm is.

The same applies for the so-called Weber contrast, which is given by Kw=(Gh-Gm)/Gm and, with the gray values present here, also for the modulation KM=(Gh-Gm)/ (Gh+Gm).

It is thus advantageous to distribute the individual marking sites in a lower spatial frequency, since in this way, the brightness impression of the total area is lowered. Nevertheless, when optimizing the contrast, care must be taken that, when tilting, sufficient areal coverage is necessan> for the image components that become light, and that the image context is not lost due to pixels that are too far apart. To accommodate these requirements, preferred line screens lie between about 0.4 mm and 1.2 mm, the range between 0.5 mm and 1 mm being particularly preferred.

In precisely this way, the overall brightness can be lowered in that the darkest possible tone with the highest possible saturation is used for the background color. Here, it is particularly advantageous to use the intaglio printing method used in security printing, which facilitates a good saturation due to the high layer thicknesses. Since, due to the process, it is problematic to print areas with conventionally manufactured intaglio printing plates, for this, methods are preferred that permit a small-scale patterning also of lower-lying areas and, in this way, produce define color-capturing grids, as described for instance in the publications DE 100 44 711 Al and DE 198 45 440 Al, whose disclosure in this respect is incorporated in the present application.

Instead of coating the substrate with a laser-sensitive layer, substrates that react to the laser impingement with blackening or coloring can also be used.
Also in this variant of the present invention, the sequence of the production of the two components relief and flat marking is open. For example, the arrangement of the twTo components can again correspond to the figures shown above.

Additives that support relief production can be added to the substrate. At the same time, dyes or pigments that, upon different power or energy density of the laser, cause a different color change to appear can be used with great advantage, or those that do this as a function of other laser parameters, such as wavelength or pulse duration etc.

Substrates that, even without special additives, react to different laser power or energy densities with different color impressions are also advantageous.
For example, plastics can be used for this in which, at high power or energy density, relief patterns are introduced in that beads form in the substrate due to the expansion of gases. Due to light scattering, these generally have a whitish color impression. A flat marking executed with lower energy, in contrast, yields a color change to darker tones. Here, primarily PVC, polycarbonate or PET variants are suitable as substrates.

Also the combination of the two above-described method steps is possible.
For example, in a substrate coated with laser-radiation-absorbing pigments and/or dyes, a flat marking in which the color is removed can initially be lasered. The flat marking also includes the location of the relief pattern.
Then, the relief pattern is lasered into the exposed substrate and again produces there a blackening or a color change.

Claims (35)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A method for manufacturing a security element having an optically variable pattern that includes an individualizing mark, having the method steps:

a) providing a substrate with a marking pattern having a plurality of flat markings;

b) providing the substrate with a relief pattern having a plurality of raised relief elements, the flat markings being at least partially disposed on sides of the relief elements and the marking pattern and the relief pattern being combined in such a way that different pieces of information are visible from different viewing directions, and the individualizing mark being produced in at least one of the work steps a) or b) with a non-impact method or a printing method without a fixed printing plate.

2. The method according to claim 1, characterized in that the marking pattern and the relief pattern are produced with the same method in one work step.

3. The method according to claim 1, characterized in that the marking pattern and the relief pattern are produced in separate work steps, wherein the marking pattern can be produced before or after the relief pattern.

4. The method according to at least one of claims 1 to 3, characterized in that the relief pattern is embossed in the substrate.

5. The method according to claim 4, characterized in that the relief pattern is produced with an embossing die.

6. The method according to claim 4, characterized in that the relief pattern is produced in intaglio printing.

7. The method according to at least one of claims 1 to 3, characterized in that the substrate is provided with the relief pattern by the action of a laser beam.

8. The method according to at least one of claims 1 to 7, characterized in that the relief pattern is developed in the form of a grid, preferably a grid having a constant spatial frequency.

9. The method according to at least one of claims 1 to 8, characterized in that the substrate is provided with the marking pattern by the action of a laser beam.

10. The method according to at least one of claims 1 to 8, characterized in that the marking pattern is imprinted on the substrate.

11. The method according to claim 10, characterized in that the marking pattern is applied to the substrate in the ink-jet method or with a digital printing method that works with low pressure.

12. The method according to claim 10, characterized in that the marking pattern is produced in planographic printing, such as in the offset method, in relief printing, such as in letterpress printing or in the flexographic printing method, in screen printing or in a thermographic method, such as in the thermotransfer method.

13. The method according to at least one of claims 1 to 12, characterized in that the marking pattern is developed in the form of a grid, preferably a grid having a constant spatial frequency.

14. The method according to at least one of claims 1 to 13, characterized in that the individualizing mark comprises letters, numerals or a symbol code, such as a barcode or matrix code.

15. The method according to at least one of claims 1 to 14, characterized in that the substrate and/or the surface of the security element includes further security substances that are activated, exposed, covered, partially destroyed or removed in at least one of the work steps a) or b).

16. A security element having an optically variable pattern that includes a marking pattern having a plurality of flat markings and a relief pattern having a plurality of raised relief elements, the marking pattern and the relief pattern being combined in such a way that different pieces of information are visible from different viewing directions, characterized in that - the flat markings are disposed at least in part on sides of the relief elements, a relief element and a flat marking disposed on at least one of its sides together forming a pattern element, and in that - the marking pattern and/or the relief pattern is provided with an individualizing mark that is produced with a non-impact method or a printing method without a fixed printing plate.

17. The security element according to claim 16, characterized in that the relief elements of the relief pattern are disposed in the form of a grid, preferably a grid having a constant spatial frequency.

18. The security element according to claim 16 or 17, characterized in that the flat markings of the marking pattern are disposed in the form of a grid, preferably a grid having a constant spatial frequency.

19. The security element according to claim 17 and 18, characterized in that the grids of the relief pattern and of the marking pattern exhibit the same spatial frequency.

20. The security element according to claim 17 and 18, characterized in that the relief pattern and the marking pattern exhibit slightly different spatial frequencies to produce beat or Moiré effects.

21. The security element according to at least one of claims 16 to 20, characterized in that the flat markings exhibit at least one colored area.

22. The security element according to at least one of claims 16 to 21, characterized in that the flat markings exhibit multiple colored areas that are disposed at least in part on different sides of the relief elements.

23. The security element according to at least one of claims 16 to 22, characterized in that the optically variable pattern includes a plurality of pattern elements that depict a multicolored image motif whose visual impression varies when the viewing angle is changed.

24. The security element according to at least one of claims 16 to 23, characterized in that the individualizing mark comprises letters, numerals or a symbol code, such as a barcode or matrix code.

25. The security element according to at least one of claims 16 to 24, characterized in that the relief pattern and the marking pattern are disposed on a single- or multi-layered substrate.

26. The security element according to at least one of claims 16 to 25, characterized in that the relief pattern and the marking pattern are disposed on a substrate that is single- or multi-layer coated, printed, pasted, clad or laminated.

27. The security element according to at least one of claims 16 to 26, characterized in that the substrate and/or the surface of the security element exhibits further, especially machine-readable security features.

28. The security element according to at least one of claims 16 to 27, characterized in that the marking pattern and the relief pattern are combined with one or more further layers that depict a pattern or image that is visually perceptible when viewed vertically.

29. The security element according to at least one of claims 16 to 28, characterized in that the relief elements are developed to be tactilely perceptible.

30. The security element according to at least one of claims 16 to 29, characterized in that the relief pattern includes a plurality of non-line-shaped relief elements.

31. The security element according to at least one of claims 16 to 30, characterized in that at least a portion of the non-line-shaped relief elements exhibits substantially the shape of a tetrahedron, a spherical segment, a pyramidal frustum, a conical frustum, a cylindrical segment, a torus segment, an oval, a teardrop or a pyramid.

32. The security element according to at least one of claims 16 to 31, characterized in that the relief pattern is broken down into sub-regions in which different partial relief patterns are disposed.

33. The security element according to claim 32, characterized in that the partial relief patterns each form a grid of the same line screen and, in at least two adjoining sub-regions, the grids of the partial relief patterns are disposed offset by a fraction of the line screen, especially by about one-third of the line screen.

34. A data carrier, especially a value document, such as a banknote, identification card or the like, having a security element according to one of claims 1 to 33.

35. A use of a security element according to at least one of claims 1 to 33 or a data carrier according to claim 34 for securing goods of any kind against counterfeiting.