WO2014106517A1

WO2014106517A1 - Method for producing a security element having a laser-sensitive recording layer

Info

Publication number: WO2014106517A1
Application number: PCT/EP2013/003417
Authority: WO
Inventors: Harald Reiner; Daniela Otto; Georg Depta
Original assignee: Giesecke & Devrient Gmbh
Priority date: 2013-01-04
Filing date: 2013-11-13
Publication date: 2014-07-10
Also published as: EP2941355A1; DE102013000152A1; EP2941355B1; PL2941355T3

Abstract

The invention relates to a method for producing a security element (12) for security papers, value documents, and other data carriers, wherein a substrate (20) is provided with a laser-sensitive recording layer (22) at least in some regions, which recording layer has a visual initial appearance and is composed of an ink mixture that comprises at least one laser-absorbing mixture component, a first laser radiation having first laser parameters is applied to the laser-sensitive recording layer (22) in a first sub-region (26) in order to produce there a first target appearance that is changed with respect the initial appearance, a second laser radiation having second, different laser parameters is applied to the laser-sensitive recording layer (22) in a second sub-region (28) in order to produce there a second target appearance that is changed with respect to the initial appearance and that is different from the first target appearance, wherein the first laser radiation and the second laser radiation are produced by means of only one laser source (32) and only one imaging optical system, and the first sub-region (26) and the second sub-region (28) are thereby produced in register with each other.

Description

Method for producing a security element with a laser-sensitive

recording layer

The invention relates to a method for producing a security element for security papers, value documents and other data carriers. The invention also relates to a security element, which is produced by such a method, a data carrier, in particular a security paper or valuable article, with such a security element and a device for carrying out said method.

Identity cards, such as credit cards or identity cards, have long been personalized by laser engraving, for example, provided with a passport photo or other personal information. To personalize a badge by laser engraving usually the optical properties of the substrate material of the card are irreversibly changed by suitable guidance of a laser beam in the form of a desired marking, in particular blackened. Based on this, the present invention seeks to provide an advantageous method for producing a security element of the type mentioned.

This object is solved by the features of the independent claims. Further developments of the invention are the subject of the dependent claims.

According to the invention, in a method for producing a security element for security papers, value documents and other data carriers, it is provided that a substrate is at least partially provided with a laser-sensitive recording layer which has a visual output appearance, and which consists of a color mixture having at least one laser-absorbing mixture component, the laser-sensitive recording layer is acted upon in a first portion with a first laser radiation with first laser parameters, In order there to produce a relation to the initial appearance changed, first target appearance, the laser-sensitive recording layer is applied in a second portion with a second laser radiation with second, different laser parameters, there compared to the initial appearance changed and from the first target Appearance image to produce distinctive second target appearance, wherein the first and second laser radiation are generated with only one laser source and only one imaging optics, and the first and second Teilbere I thereby be generated in Passer to each other.

The different laser parameters of the first and second laser radiation may in particular consist of a variation of the intensity, the energy and / or the pulse peak power of the laser radiation. The intensity of the laser radiation can be set above all by focusing the laser beam, the energy of the laser radiation primarily by the marking speed and the diode current of a diode pump laser and the pulse peak power first by selecting pulse mode or continuous wave mode and pulse mode by the pulse length. As described in more detail below, the laser source is preferably ten designs for generating the first target appearance in pulse mode and for generating the second target appearance in continuous wave mode operated. Here, as elsewhere in this description, the terms "first" and "second" are not intended to indicate an order or a ranking, but are intended to refer to only two distinct portions, laser parameters and appearances.

The laser source is advantageously provided in the context of the invention with a Q-switch, which allows in a conventional manner the generation of pulses with high peak power. The opening time of the Q-switch determines the pulse character of the laser radiation. In a continuously open Q-switch, a continuous wave laser beam is emitted, and periodic opening and closing of the Q-switch produces pulsed laser radiation. A short opening time of the Q-switch (for example, a ratio of opening time to charging time of 1: 5 or less) results in short laser pulses with pulse durations of preferably 20 ns or less, from 10 ns to 20 ns, or even 10 ns or less. Such short pulses have a very high power. With their short exposure time, they are particularly suitable for ablation of the absorbent mixture component from the applied recording layer.

An average opening time of the Q-switch (for example a ratio of opening time to charging time between 1: 2 and 2: 1) leads to longer pulses with pulse durations from a few hundred nanoseconds to a few microseconds and correspondingly lower power. With these pulses, thermal effects increasingly come to the fore with increasing pulse duration. Finally, with continuous wave operation of the laser source, the Q-switch is always open. The power of the laser beam is the lowest and due to the long exposure time the thermal effects dominate. As a result of the generation according to the invention of the partial regions, the first and second partial regions are in register with one another, so that two different but mutually aligned modification regions can be produced in the recording layer. For example, a partial area may form a frame for the second partial area, or the partial areas may be supplemented to form an overall motif. In both cases, register fluctuations of the two subregions, which are often unavoidable in the production in separate steps, are particularly noticeable. The procedure according to the invention makes it possible to avoid such register fluctuations since the different appearances with the same laser source are produced in only one operation only by the use of different operating modes of the same laser source. Another important aspect of the invention is that the different appearances are produced in the same recording layer and not caused by the different responses of different recording layers to the laser application.

The portions created by the laser application together form a visually recognizable mark in the recording layer and the security element. The marking may, for example, consist in the numbering while replacing or supplementing letterpress numbering, for example on banknotes. It may also consist of numbers and / or letters, which may be derived in particular from the cited number. For example, the numbers or letters may be obtained from a digit by cryptographic methods, or they may consist of only one repetition of a portion of the number. The marker may also be a value number, such as a banknote, a logo, such as a publisher logo of a central bank, a date or time or an indication derived therefrom, or even a graphical element or a code such as bar code, matrix code or multi-color code.

As a substrate of the security element in particular carrier materials made of cotton fibers, polymers or a substrate with a hybrid structure in question. The security element can be part of a data carrier that provides the substrate, or can be applied with its substrate to a data carrier.

The laser-sensitive recording layer can be applied over the entire area, but at present it is preferred that the laser-sensitive recording layer is applied in the form of a grid, in particular in the form of a line, dot or cross grid. The dimensions of the raster forming raster elements and the distances of the raster elements are advantageously below the resolution limit of the naked eye, in particular below 200 μητι, so that the recording layer appears completely flat when viewed without tools. In particularly advantageous configurations, the laser-sensitive recording layer is formed by a printing layer, preferably a monochrome printing layer. For the application of the recording layer, all printing processes, in particular screen printing, intaglio printing, background printing, offset printing, gravure printing or letterpress printing, come into consideration.

Preferably, the initial appearance of the laser-sensitive recording layer in a homogeneous color impression, for example in the monochrome impression of a closely screened printing layer.

In all designs, the recording layer may contain only a single laser-sensitive mixture component derived from the first and second Laser radiation is influenced due to the different laser parameters in different ways or even in different strength and thereby generates the different target appearances. For example, by pulsed laser application with short laser pulses of about 10 ns (first laser parameter), only the absorbing mixture component can be removed from the recording layer, while the entire recording layer is removed by laser application in continuous wave mode (second laser parameter). However, the color mixture of the recording layer can also contain a plurality of laser-sensitive mixture components, wherein, for example, a first component is influenced essentially only by the first laser radiation, and a second component is influenced essentially only by the second laser radiation, so that different target appearances result. The recording layer may be broadband absorptive, but currently recording layers having IR absorbing components are preferred.

In advantageous embodiments, the color mixture of the laser-sensitive recording layer contains optically variable color pigments, non-absorbing mixture components being in particular optically variable liquid crystal pigments or a transparent intaglio and for the laser-absorbing mixture components, for example optically variable interference layer pigments. Other irreversible color components which are irreversible in their optical properties, such as an intaglio printing ink, a metallic effect ink or metallic pigments, a luminescent color or luminescent pigments, luster pigments or a thermochromic color, are also suitable for the laser-absorbing mixture components. In further advantageous embodiments, the color mixture of the laser-sensitive on drawing layer as a laser-absorbing mixture component contains carbon black. For offset inks, weight fraction of carbon black of 10% to 30%, preferably of 15% to 30%, has proven to be particularly advantageous. For intaglio inks, the carbon black content is advantageously above 3%, in particular above 6%.

According to an advantageous variant of the method, the laser-sensitive recording layer is completely removed by the first or second laser radiation, and the first target appearance or the second target appearance consists in the appearance of the substrate. If the substrate is an uncoated paper substrate, for example, the first or second target appearance is the paper white of the paper substrate, but the use of other substrates or coated substrates may also result in a different first or second target appearance.

In a further advantageous variant of the method, at least one laser-absorbing mixture component is at least partially removed from the laser-sensitive recording layer by the first or second laser radiation, and the first target appearance or second target appearance consists in particular in a lightening of the homogeneous color impression of the laser-sensitive recording layer. Depending on the laser parameters used, different proportions of the laser-absorbing mixture components can be removed and thus different effects, in particular different degrees of brightening, can be produced. Different strong effects or brightening can be combined in a single drawing layer. In this case, it is also possible, by the laser radiation in a further sub-range only to the smallest amounts of the absorbent mixture component remove so that the visual color impression is substantially retained there.

Depending on the material used, various mechanisms may be considered for the removal of the laser-absorbing mixture components. For example, a laser-absorbent blend component may be bleached, vaporized, altered in reflectivity, or converted to a material having other optical properties. All these modifications are summarized in this description under the term "removal of the laser-absorbing mixture component" since the laser-absorbing mixture component is no longer in its original form as a laser-absorbing component after its modification , the generation of a color change, the lightening of a color, the change of the tipping color of an effect color mixture or the local change of the polarization properties or the luminescence properties of the drawing layer in question.

In a currently particularly preferred embodiment, laser exposure in pulsed mode with short laser pulses of about 10 ns to 20 ns (first laser parameter) removes at least one absorbing mixture component at least partially from the color mixture of the recording layer and becomes the continuous laser mode by second laser exposure entire recording layer removed. Furthermore, in particular by the above-mentioned laser application in pulse mode and / or continuous wave mode, the surface properties of the color mixture can also be changed. Already the two variants of complete removal of the laser-sensitive recording layer and the removal of the absorbent mixture components from the same recording layer enable the generation of visually attractive, perfectly matched modification regions in the recording layer using only one laser source. By adding further effects, such as a laser-induced blackening of the substrate and / or a laser-induced foaming of the substrate, the design variety can be further increased and even extended by tactile elements.

In an advantageous embodiment, when a raster-shaped recording layer is used, provision may be made for the substrate to be blackened and / or foamed by the first or second laser radiation in intermediate spaces between the raster elements of the laser-sensitive recording layer.

In an advantageous development of the invention, the substrate can be provided only in regions with the laser-sensitive on drawing layer. In addition to the laser-sensitive recording layer, the substrate in an outer region of the recording layer can then also be exposed to the first or second laser radiation, and the substrate can be blackened and / or foamed in the exposed outer region by the action of the laser radiation. Since the recording layer and the exterior are subjected to the same laser source, the blackening or foaming of the substrate can be performed in register with the above-described modification regions of the recording layer. For example, a partial area may form a motif in the recording layer, which continues without register fluctuations in the adjacent outer area of the substrate. With particular advantage, the laser-sensitive recording layer is exposed to laser radiation with different laser parameters even in three or more subregions in order to produce different target appearances which are different from the original appearance, the laser radiation for applying the three or more subregions with only one Laser source and only one imaging optics is generated.

The transitions between the first and second and possibly further subregions can be erratic or fluid. In the latter case, for example, the laser parameters can be varied along ramps along with the duration of the marking. The change can not only be linear, but also formed with other, even unsteady, functions to produce nonlinear changes and jumps in the laser parameters. For example, the opening time of the Q-switch during the generation of a line-shaped mark can be extended continuously until finally continuous wave operation is achieved. As a result, for example, a distinctly colored line, in which initially only soot particles are removed from the color mixture, slowly become brighter, until finally only the substrate color is visible. It is understood that multiple ramps for different laser parameters can run simultaneously.

It goes without saying that the applied subregions can also overlap. The order of exposure to different laser parameters can decide the appearance ultimately produced since absorbing mixture components are no longer available after their removal for subsequent laser modification. In further advantageous embodiments, a visually appealing appearance of the security element is associated with high security against counterfeiting, for which purpose the first and / or second partial area is first subjected to pulsed laser radiation. In this case, marking spots are generated in the laser-sensitive recording layer at least in one of the exposures to laser radiation in the pulse mode by the individual laser pulses, which can be visually separated from each other. Advantageously, spatially inhomogeneous marking spots having a substantially circular and / or annular appearance are produced at least in one of the exposures to laser radiation in pulsed operation, the edges of the marking spots in particular appearing clearly. The marking spots are advantageously produced overlappingly, at least in partial areas, so that the overlapping direction of the marking spots indicates the order and direction of the application of the laser pulses. Typically, the sizes of the marker patches are between 10 μιη and 1 mm, preferably between 50 μπι and 500 μπι.

The laser application is advantageously carried out with an infrared laser in the wavelength range from 0.8 μιη to 3 μπ, in particular a Nd: Y AG laser or a Nd: YV0 ₄ laser. In pulsed operation, the pulse duration is preferably shorter than usual with marking lasers and is advantageously between 5 ns and 25 ns, in particular between 5 ns and 15 ns. The invention also includes a security element for securing security papers, documents of value and other data carriers, which is produced by the method described above. The security element contains a substrate which is provided, at least in regions, with a laser-sensitive recording layer which has a visual output appearance and which consists of a color mixture comprising at least one laser-absorbing mixture component, in a first subregion of the laser-sensitive recording layer by the action of a first laser radiation With the first laser parameters, a first target appearance modified compared to the initial appearance is generated, in a second subarea of the laser-sensitive recording layer by the action of a second laser radiation with second, different laser parameters a change from the initial appearance and from the first target appearance distinctive, second target appearance is generated, and the first and second sub-area are in the register to each other.

In an advantageous development of the invention, the substrate is provided only in regions with the laser-sensitive recording layer, and the substrate is blackened and / or foamed in an outer region of the recording layer by the action of laser radiation in the register with the first and / or second portion. The laser-sensitive recording layer can be applied over the entire area, or is preferably grid-shaped, in particular in the form of a line, dot or cross grid. Furthermore, the laser-sensitive recording layer is advantageously formed by a printing layer, preferably a monochrome printing layer. In an advantageous embodiment, the laser-sensitive recording layer in the first and / or second partial area has a multiplicity of marking spots generated by individual laser pulses, which can be visually separated from one another. The marking patches are preferably formed inhomogeneously inhomogeneous with a substantially circular and / or annular appearance, wherein in particular the edges of the marking patches clearly appear. Suitably, the marker patches may overlap at least in subregions, the overlap direction of the marker patches indicating the order and direction of exposure to the laser pulses.

For the embodiments with marking spots produced by individual laser pulses, a polymer substrate or a composite substrate is particularly suitable, the latter preferably having a layer sequence foil / paper / foil or paper / foil / paper. Such composite substrates are also often referred to as hybrid substrates. The laser-sensitive recording layer is advantageously formed by an offset printing layer.

The invention further comprises a data carrier with a Sicherheitssele- ment of the type described. In this case, the security element may be part of the data carrier by this provides the substrate of the security element, or the security element may be applied with its substrate on a separate disk. The data carrier may in particular be a banknote, in particular a paper banknote, preferably a cotton paper banknote, a polymer banknote or a foil-paper composite banknote. The latter preferably has a layer sequence foil / paper / foil or paper / foil / paper. The data carrier can also be an identification card, in particular a credit card, a Bank card, cash card, authorization card, identity card, passport or passport personalization page.

Finally, the invention also includes an apparatus for carrying out the described method, with

Means for applying a laser-sensitive recording layer to a substrate, a laser source which can be operated with different laser parameters, in particular both in continuous wave mode and in pulse mode, scanning optics for applying laser radiation of the laser source to the laser-sensitive recording layer, and a control device for Driving the laser source and the scanning optics to apply the laser-sensitive recording layer with laser radiation of the laser source with different laser parameters, in particular both with laser radiation of the laser source in continuous wave mode and with laser radiation of the laser source in the pulse mode.

The laser source is preferably an infrared laser in the wavelength range from 0.8 μπι to 3 μπι, in particular a Nd: Y AG laser or Nd: YV0 ₄ - laser. As described in more detail above, the laser source is advantageously provided with a Q-switch, which enables the generation of laser pulses with high peak power. Further exemplary embodiments and advantages of the invention are explained below with reference to the figures, in the representation of which a representation in terms of scale and proportions has been dispensed with in order to increase the clarity.

Show it:

1 is a schematic representation of a banknote with a security element according to the invention,

1 shows a schematic cross-sectional view of the security element of FIG. 1, a schematic representation of a laser inscription to explain its operating principle when carrying out a method according to the invention, FIG.

4 and 5 show two ways of modifying the laser-sensitive recording layer by laser application, wherein (a) shows in each case a plan view of a security element with a substrate and a laser-sensitive printing layer in the form of a line grid with parallel printing lines, and (b) respectively a cross section of FIG FIGS. 6 and 7 show two further possibilities for modifying the laser-sensitive recording layer and the substrate by laser application, in which (a) in each case a plan view of a security element with a substrate and a laser-sensitive printing layer in the form of a line grid with parallel printing lines (b) shows in each case a cross section of the security element along the line BB, that is, along one of the printing lines of (a), and (c) shows a cross section along the line CC of (a), which is shown in FIG - gap between two lines of pressure, and

8 shows in (a) a plan view of a composite substrate with a laser-sensitive offset ink layer, which is provided by pulsed laser radiation with a multiplicity of overlapping marking spots, and in (b) a security element with a more complex motif (digit "7"). ), with a plurality of marking spots arranged along the outline of the motif, and a completely removed inner area. The invention will now be explained using the example of security elements for banknotes and other value documents. Fig. 1 shows a schematic representation of a banknote 10, which is provided with a security element 12 according to the invention. In the security element 12, in the manner described in more detail below with only one laser source by a combination of two different laser marking parameters, in this case by a combination of continuous and pulsed laser radiation, a motif is generated with a plurality of mutually standing in the register subregions, each with a different visual appearance. For example, the security element 12 shows a motif with a dark blue background 14, with a paper-white appearing letter sequence 16, which is shown in the figure only by the letter "A" and with a light blue appearing ornamental line pattern 18, which stands in the perfect register for the letter sequence 16 , For a more detailed explanation, Fig. 2 shows the security element 12 of Fig. 1 schematically in cross section. On the paper substrate 20 of the banknote 10, a laser-sensitive on drawing layer is applied, which consists in the embodiment of a monochrome, dark blue print layer 22 of a laser-sensitive ink. The print layer 22 consists of a color mixture which has at least one mixture component 23 which absorbs the radiation of the laser source used for marking, and which further comprises non-absorbing color components 25. The printing layer 22 is applied in the form of a line grid with parallel printing lines 24 having a width of about 100 μm and a center-to-center distance of about 150 μm, so that the visual impression of a homogeneous dark blue surface arises when viewed without auxiliary means. The cross-section of FIG. 2 runs along one of the printing lines 24 of the line screen, so that the locking of the printing layer in the illustration of FIG. 2 is not visible. The printing ink used can be broadband absorbent, preferably a printing ink with IR-absorbing components is used.

The print layer 22 was then subjected to a first laser radiation in the continuous wave mode in such a selected laser parameters in a first portion 26, which forms with its shape the letter sequence 16 shown in Fig. 1, that the print layer 22 was completely removed in the portion 26, without while changing the substrate 20 itself. In the partial region 26, therefore, a first target appearance, which is modified compared to the dark blue initial appearance, is visible, which is formed by the paper-white appearance of the banknote paper 20.

In a second subarea 28, which forms the ornamental line pattern 18 of FIG. 1 with its shape, the print layer 22 has a second Laser radiation in pulsed operation at such selected laser parameters acted upon that only the laser-absorbing mixture component 23 was removed from the print layer 22, the non-absorbing ink constituents 25, however, remain in the print layer 22. The laser-absorbing mixture component 23 can be bleached, vaporized, changed in its reflection properties, or converted into a material having different optical properties. In the spaces 24 'between the printing lines 24, the substrate 20 is not changed even by the laser application. In the schematic representation of FIG. 2, the laser-absorbing mixture component 23 is completely removed in the second partial region 28 for the sake of clarity. In practice, however, the laser-absorbing mixture component 23 is usually only partially, for example 5% to 95% removed. As a result of the partial or complete removal of the laser-absorbing mixture component 23 of the printing layer 22, a brightening of the dark blue starting color occurs in the partial region 28, so that there results a second target appearance which consists of a light blue color impression. Depending on the remaining proportion of the laser-absorbing mixture component 23 and also the color effect of the non-absorbing color components 25, different degrees of brightening can be achieved. Furthermore, it is also conceivable that in the variant according to FIG. 2, the printing layer 22 is not completely removed in the partial region 26, but only partially, eg to 40% to 99%.

Since the first and second laser radiation were generated with only one laser source in only one operation and with only one imaging optics, as described in more detail below, the subregions 26 and 28 have no register tolerances, but can be positioned with high accuracy to each other. As a result, the security element 12 thus contains a motif with a dark blue background 14 (initial appearance) and a a paper-white appearing letter sequence 16 (first target appearance), which is passer exactly surrounded by a light blue line ornament 18 (second target appearance). A particular advantage of the method according to the invention is that different and perfectly matched visual appearances can be produced by the combination of different laser marking parameters, in particular continuous and pulsed laser radiation of a single laser source, even in a monochromatic recording layer.

The manufacturing method will now be explained in more detail with reference to FIG. 3, which schematically shows a laser marker 30 according to the invention. The laser marker 30 contains a laser source 32, for example a Nd: YV0 laser with a wavelength of 1064 nm, which can be operated with the aid of a Q-switch both in continuous wave mode (cw) and in pulse mode. Advantageously, the opening time of the Q-switch within the period can be set freely. For controlling the laser source 32, including the choice of operating mode (continuous wave / pulsed) and the other desired laser parameters, a control unit 34 is provided.

The laser beam 36 emitted by the laser source 32 is deflected by two movable mirrors 38, one of the mirrors producing the deflection in the x direction, the other mirror producing the deflection in the y direction. A plan field lens 40 focuses the laser beam 36 at the desired portion of the security element 12 of a banknote benefit where it modifies the initial appearance of the print layer 22 or an adjacent substrate area as described. The energy or power input into the Printing layer 22 or the substrate 20 can be influenced not only by the operating mode of the laser and by the energy or power of the laser radiation, but also by the scanning speed of the laser beam 36, which can also be selected with the aid of the control device 34. In addition, the surface intensity of the radiation can be adjusted by an optical system, for example a focus shifter 42, which determines the beam diameter of the laser radiation impinging on the security element 12, and which can likewise be controlled by the control unit 34. In this way, different line widths and different laser beam intensities can be realized.

In order to produce the two above-mentioned target appearances in the security element 12, in the first subarea 26, for example, with a continuous wave laser radiation of an Nd: YV0 ₄ laser at a power between 75 W and 105 W and a scan speed between 2 m / see s and 7 m / s are worked. In the second subregion 28, it is possible to operate with 10 ns to 20 ns pulses at a pulse frequency of 30 kHz with a charging time of 5 μβ / ΡηΙβ and a scanning speed of approximately 4 m / s in pulse mode.

While Fig. 3 illustratively shows a security element of only one banknote benefit, in practice a banknote sheet is typically processed with a plurality of banknote benefits, with multiple laser sources capable of processing one benefit in parallel, and with each laser source sequentially utilizing multiple uses of the signature in accordance with the described method processed. Each benefit is processed but only by a laser source and acted upon by this with laser radiation with different laser parameters, in particular with both continuous and pulsed laser radiation. In addition to the two possibilities of changing the visual appearance of a laser-sensitive on-drawing layer by complete ablation or by partial or complete removal of the laser-absorbing mixture components, there are also other possibilities including the substrate of the security element, which are now related to the possibilities already described to be explained on the figures 4 to 7. The various modifications and the resulting appearances are each illustrated separately for clarity, but it should be understood that within the scope of the invention, the initial appearance of the recording layer in two or more portions by using different laser parameters, in particular both of pulsed and of continuous wave radiation of the same laser source is changed into two or more different target appearances.

First, Fig. 4 (a) shows a plan view of a security element 50 having a substrate 52 and a monochrome laser-sensitive print layer 22 formed in the form of a line grid with parallel print lines 24 and spaces 24 '. The print layer 22 consists of a color mixture with laser-absorbing mixture components 23 and with non-absorbing color components 25. FIG. 4 (b) shows a cross-section of the security element 50 along the line BB, ie along one of the print lines 24 of FIG. 4 (a). The printing lines 24 are not drawn to scale in the figure and typically have a width of about 100 μπι and a center-to-center distance of about 150 μη in order to produce a print layer, which gives a homogeneous color impression when viewed without aids. The higher the areal coverage of the print layer 22, the higher the contrast achievable by lightening or by complete ablation. The printing layer 22 with the printing lines 24 was applied in a partial region 54, in the embodiment in the form of the letter "A", with laser radiation of the laser source 32 in continuous wave mode and with laser parameters selected in such a way that the printed layer 22 in the partial region 54 was completely removed, without In this case, the security element 50 exhibits in the partial area 54 a changed appearance compared to the homogeneous color impression of the print layer 22, which is given by the appearance of the substrate 52. If the substrate 52 is an uncoated paper substrate, as in the exemplary embodiment of FIG 2, the partial area 54 appears paper-white; using other or coated substrates may also result in a different visual impression.

Fig. 5 (a) also shows a plan view of a security element 50 having a substrate 52 and the monochrome laser-sensitive print layer 22 of Fig. 4 (a), and Fig. 5 (b) shows a cross-section along the line BB, that is, along one the printing lines 24 of Fig. 5 (a). The printing layer 22 with the printing lines 24 was acted upon in a partial region 56, in the exemplary embodiment in the form of the letter "B", with laser radiation of the laser source 32 in pulse mode at such selected laser parameters that in the sub-area 56, the laser-absorbing mixture component 23 partially from On the other hand, the print layer 22 has been removed, but the non-absorbing color components 25 remain completely in the print layer 22 without changing the substrate 52 in the gaps 24 'between the print lines 24. In the sub-area 56, the security element 50 therefore faces the initial appearance a lightening, for example, a homogeneous light blue color impression.

It is understood that depending on the laser parameters used by selecting the removed portion of the laser absorbing mixture component 23 different levels of brightening can be generated. Different degrees of brightening can be combined in a print layer 22 of a security element. For example, 30% of the existing laser-absorbing mixture component 23 can be removed in a first subarea, 60% of the existing laser-absorbent mixture component 23 in a second subarea, and 90% of the existing laser-absorbing mixture component 23 in a third subarea, thereby producing different whitening steps. FIG. 6 shows a further modification possibility, which also detects the substrate 52 in addition to the printing layer 22. For clarification, in Fig. 6 (a), the edge portion between the print layer 22 and the adjacent outer portion 60 outside the print layer 22 is shown. Fig. 6 (b) shows a cross-section of the security element 50 along the line BB of (a) along one of the pressure lines 24 and Fig. 6 (c) shows a cross-section along the line CC of (a), which is in a gap 24 ' between two lines of pressure 24 runs. In the exemplary embodiment of FIG. 6, the laser-modified subregion is not extended in a planar manner, unlike in the exemplary embodiments of FIGS. 4 and 5, but consists in the outline shape of the letter "C".

For marking pulsed laser radiation of the laser source 32 is used with medium pulse peak power, for example, with an opening time of the Q-switch of 5 μ8 at 50 kHz pulse frequency, a medium intensity, generated for example by a beam width of 0.6 mm and a mean line energy, for example generated by a marking speed of 6 m / s. As can best be seen in FIG. 6 (b), the effect of the laser radiation causes the laser-absorbing mixture component 23 to be partially removed from the printing layer 22 or the printing lines 24, so that there, similar to the embodiment of FIG. 5, a brightening 58 results. In the outer region 60 lying outside the print layer 22, the effect of the laser radiation on the selected laser parameters leads to one

Blackening 62 of the substrate. As illustrated in Fig. 6 (c), the same blackening effect results in the gaps 24 'between the printing lines 24 where the laser radiation also strikes the substrate directly. Thus, while there is a uniform blackening in the form of the right half of the letter "C" in the outer area 60, the appearance of the left half of the letter "C" in the area of the print layer 22 results from a superposition of the alternating brightenings 58 of the printing lines 24 and the blackened lines Areas 62 in the spaces 24 '. Because of the small raster width of the printing lines 24, the brightening 58 and the blackened areas 62 are not separately recognizable with the naked eye, but complement each other for the viewer to a homogeneous overall impression. Due to the additionally present blackened regions 62, the target appearance of the print layer 22 in this variant is darker than in the case of the pure brightening of the print layer 22 described in conjunction with FIG. 5.

The modification option of FIG. 7 also includes the substrate 52. Analogous to the representation of FIG. 6, FIG. 7 (a) shows a plan view of FIG Edge region of print layer 22 and outer region 60, Fig. 7 (b) shows a cross section of the security element 50 along the line BB of (a) along one of the printing lines 24 and Fig. 7 (c) shows a cross section along the line CC of (a ) in a gap 24 'between two printing lines 24. The laser-modified portion is in the embodiment of FIG. 7 in the outline of the letter "D".

For marking pulsed laser radiation of the laser source 32 with, compared with the laser parameters of Fig. 6, higher pulse peak power is used sets, for example, with an opening time of the Qüteschalters of 3 μβ at 30 kHz pulse frequency, a higher intensity, for example, generated by a beam width of 0 , 4 mm and a higher line energy, for example generated by a marking speed of 3 m / s. As shown in FIGS. 7 (b) and 7 (c), the action of the laser radiation at the selected laser parameters results in blackening and in addition to a foaming 64 of the substrate. This effect results both in the area of the intermediate spaces 24 ', as shown in FIG. 7 (c), and in the area of the printing lines 24, which are completely removed by the laser radiation and where, in addition, the underlying substrate is blackened and foamed.

In this way, a blackened and foamed region 64 in the form of the letter "D" results, which equally covers the area of the print layer 22 and the outer area 60 and which, in addition to the visual impression of the blackening by the foaming surface of the substrate, can also be tactually detected Authenticating feature. In a modification of the design of FIG. 7, the action of the laser radiation in the printing layer 22 only leads to a whitening 58, while in the outer region 60 a blackened and foamed region 64 is formed.

In some designs, a visually appealing appearance of high security against counterfeiting can be achieved by impinging on the first and / or second partial area with laser radiation in pulse mode. FIG. 8 (a) shows, to illustrate the underlying principle, a plan view of a composite substrate 70 which carries a laser-sensitive recording layer having a color layer 72 applied in an offset process whose carbon black content in the exemplary embodiment is about 25%. The color layer 72 was exposed to laser radiation in pulsed operation, wherein each laser pulse generated by the interaction with the soot-containing ink layer a marking patch 74. The marker patches 74 are spatially inhomogeneous and show a substantially annular appearance. In particular, the edges 76 of the marking patches appear clearly without the realization of this effect being understood in detail so far.

If the pulse frequency and the scanning speed of the laser radiation are adjusted to each other appropriately, the individual marking spots 74 overlap, but because of the protruding edges 76, they can easily be visually separated from one another when viewed with a magnifying glass or the like. In addition, since the edges of the marker patches 74 are clear even with the overlapping patches, and later generated patches 74 partially overlap earlier-produced patches, from the overlap direction, the patch patches may also change the order and the direction 78 is closed in which the marker patches 74 have been sequentially generated.

FIG. 8 (b) shows, as a more complex motif 80 of a security element, the number "7", which may for example be part of a serial number inscribed in the recording layer 72 of FIG. 8 (a) by laser radiation. In this case, a plurality of marking spots 74, which are arranged along the outline of the motif 80, were first of all generated in a first partial region 82 with laser radiation in pulsed operation with first laser parameters. Subsequently, the drawing layer 72 in the inner region of the motif (second subarea 84) was completely removed with second laser parameters, without, however, changing the substrate 70 itself.

As shown in FIG. 8 (b) and indicated by the arrows 86, from the overlapping direction of the marker patches 74, the order and direction in which the marker patches 74 have been formed can be deduced.

In addition to the appealing, sub-structured visual appearance which results from the overlapping marking patches 74 and their edges 76, the security element provided with the motif 80 also has an increased security against forgery, since the sequence, the direction and the distance Marking marks 74 are encoded in the security element additional information that are difficult to reproduce for a potential counterfeiter. LIST OF REFERENCE NUMBERS

10 banknote

12 security element

14 Background

16 letter sequence

18 ornamental line pattern

20 paper substrate

22 print layer

23 laser-absorbing mixture component

24 printing lines

24 'spaces

25 non-absorbent paint components

26,28 sections

30 laser markers

32 laser source

34 control unit

36 laser beam

38 mirrors

40 field lens

42 focus shifter

50 security element

52 substrate

54, 56 sections

58 lightening

60 outdoor area

62 blackening

64 foaming

70 composite substrate 72 laser-sensitive ink layer

74 markers

76 edges of the marker patches

78 direction of generation

80 motif

82 first subarea

84 second subarea

86 direction of generation

Claims

Patent claims

1. A method for producing a security element for security papers, value documents and other data carriers, in which a substrate is at least partially provided with a laser-sensitive recording layer having a visual output appearance, and which consists of a color mixture, the at least one laser-absorbing Mixture component, the laser-sensitive recording layer is acted upon in a first portion with a first laser radiation with first laser parameters to produce a relation to the initial appearance modified first target appearance, the laser-sensitive recording layer in a second portion with a second laser radiation with second , Different laser parameters is applied to there to produce a relation to the initial appearance changed and different from the first target appearance second target appearance, wherein the first and z wide laser radiation can be generated with only one laser source and only one imaging optics, and the first and second partial area are thereby generated in the register to each other.

2. The method according to claim 1, characterized in that one of the subregions forms a frame for the other subarea, or that the first and second subarea complement each other to form an overall motif.

3. The method according to claim 1 or 2, characterized in that the initial appearance of the laser-sensitive recording layer is in a homogeneous color impression.

4. The method according to at least one of claims 1 to 3, characterized in that the laser-sensitive recording layer is completely removed by the first or second laser radiation, and that the first target appearance or second target appearance in the appearance of the substrate.

5. The method according to at least one of claims 1 to 4, characterized in that at least one laser-absorbing mixture component is at least partially removed from the laser-sensitive recording layer by the first or second laser radiation, and that the first target appearance or second target appearance in particular in a Whitening of the homogeneous color impression of the laser-sensitive recording layer is.

6. The method according to at least one of claims 1 to 5, characterized in that the laser-sensitive recording layer is grid-shaped, in particular in the form of a line, dot or cross grid, applied.

7. The method according to claim 6, characterized in that blackened by the first or second laser radiation, the substrate in spaces between the raster elements of the laser-sensitive recording layer and / or is foamed.

8. The method according to at least one of claims 1 to 7, characterized in that the substrate is only partially provided with the laser-sensitive recording layer that applied to the first or second laser radiation in addition to the laser-sensitive recording layer and the substrate in an outer region of the recording layer is, and that the substrate is blackened and / or foamed in the outdoor area by the action of the laser radiation.

9. The method according to claim 1, characterized in that the laser-sensitive recording layer is exposed to laser radiation with different laser parameters in three or more partial areas, in order to each have a different target appearance, which is changed in relation to the original appearance generate, wherein the laser radiation is generated to act on the three or more portions with only one laser source and only one imaging optics.

10. The method according to at least one of claims 1 to 9, characterized in that the loading of the first and / or second partial area is carried out with laser radiation in the pulse mode.

11. The method according to claim 10, characterized in that at least one of the exposures to laser radiation in pulse operation by the individual laser pulses markings are generated in the laser-sensitive recording layer, which can be visually separated from each other.

12. The method according to claim 10 or 11, characterized in that at least in one of the exposures to laser radiation in Pulsbe- drove spatially inhomogeneous marking spots are produced with a substantially circular and / or annular appearance, preferably the edges of the marking spots clearly appear.

13. The method according to claim 11 or 12, characterized in that the marking spots are generated overlapping at least in partial areas, so that the overlapping direction of the marking spots indicates the order and direction of the application of the laser pulses.

14. The method according to at least one of claims 1 to 13, characterized in that the laser irradiation with an infrared laser in the wavelength range of 0.8 μιη to 3 μιη, in particular a Nd: Y AG laser or a Nd: YV0 ₄ laser performed becomes.

15. Security element for securing security papers, documents of value and other data carriers, produced according to one of claims 1 to 14, with a substrate which is at least partially provided with a laser-sensitive recording layer, which has a visual output appearance, and from a color mixture consists of at least one laser-absorbing mixture component, wherein in a first portion of the laser-sensitive recording layer by the action of a first laser radiation with first laser parameters a relation to the initial appearance changed, first target appearance is generated in a second subarea of the laser-sensitive recording layer, a second target appearance which is different from the original appearance and differs from the first target appearance is generated by the action of a second laser radiation with second, different laser parameters, and the first and second subregions in the register to stand by each other.

16. The security element according to claim 15, characterized in that one of the subregions forms a frame for the other subarea, or that the first and second subarea complement one another to form an overall motif.

17. A security element according to claim 15 or 16, characterized in that the substrate is only partially provided with the laser-sensitive recording layer, and that the substrate in an outer region of the recording layer is blackened by the action of laser radiation in the register with the first or second partial region and / or foamed.

18. The security element according to claim 15, characterized in that the laser-sensitive recording layer is applied in the form of a raster, in particular in the form of a line, dot or cross screen, and / or that the laser-sensitive recording layer is applied by a printing layer, preferably a monochrome printing layer is formed.

19. A security element according to at least one of claims 15 to 18, characterized in that the laser-sensitive recording layer in the first and / or second sub-area a plurality of individual by Serpulse generated markings that can be visually separated from each other.

20. A security element according to claim 19, characterized in that the marker patches are spatially inhomogeneous with a substantially circular and / or annular appearance, wherein preferably the edges of the marker patches clearly appear.

21. A security element according to claim 19 or 20, characterized in that the marker patches overlap at least in partial areas, wherein the overlapping direction of the marker patches indicates the order and direction of the application of the laser pulses.

22. The security element according to claim 19, characterized in that the substrate is a polymer substrate or composite substrate, the latter preferably having a layer sequence foil / paper / foil or paper / foil / paper.

23. A data carrier, in particular security paper or document of value with a security element according to one of claims 1 to 22.

24. Apparatus for carrying out the method according to one of claims 1 to 14, with

Means for applying a laser-sensitive recording layer to a substrate, a laser source which can be operated with different laser parameters, in particular both in continuous wave mode and in pulse mode, - a scanning optics for exposing the laser-sensitive recording layer provided with the substrate laser radiation of the laser source, and a control device for driving the laser source and the scanning optics to the laser-sensitive On drawing layer with laser radiation of the laser source with different laser parameters, in particular to act both with laser radiation of the laser source in continuous wave mode and with laser radiation of the laser source in the pulse mode.

25. The device according to claim 24, characterized in that the

Laser source is an infrared laser in the wavelength range of 0.8 μπι to 3 μπι, in particular a Nd: YAG laser or Nd: YV04 laser is.