Data carrier having a printed magnetic security feature 10001] The invention relates to a data carrier having a magnetic security feature applied by printing process and a manufacturing method for such a data carrier. [0002] For warding off forgery attempts, for data carriers of any kind, such as bank notes, shares, bonds, deeds, vouchers, checks, lottery tickets, high-quality admission tickets, passports, identification documents and other papers at risk of forgery, as well as card-shaped data carriers, in particular chip cards, there is always a need for new security features. [0003] In WO 2006/053685 A2 there is described a bank note with a bank-note specific code not visible to the viewer. This is for example a barcode which is printed with a printing ink visible only in the infrared. The bank-note-specific code is derived from a measurable property of the bank note, for example from a pattern introduced with the aid of a laser or from a feature otherwise selectively varied or an incidental feature of the bank note, such as from a gravure print element printed onto the bank note. [00041 WO 2007/110155 Al likewise describes a security element which is only recognizable in the infrared and thus not visible to a viewer. The bank note described therein comprises an upper protective layer which does not absorb infrared laser light, and a lower marking layer which absorbs the laser light. Thus, by means of short IR laser pulses there can be written information not visible to the viewer into the lower marking layer, without destroying the upper cover layer. [00051 The object of the present invention is to provide an alternative method for manufacturing a data carrier having a machine-readable security feature not visible to the viewer as well as a corresponding data carrier. [0006] This object is achieved by a method and a data carrier having the features of the independent claims. The dependent claims and the following description relate to preferred embodiments and developments.
10007] The present invention relates to printing inks having a magnetic component and is based, inter alia, on the finding that the amount of the magnetic substance in such a printing ink can be reduced after the printing onto a data carrier. Both, the amount by which the quantity of the magnetic substance is reduced and the spatial area concerned can be selectively chosen here. [0008] The security feature is thus generated by, in a first step, a printing ink being printed onto the data carrier, which contains a chosen amount of a magnetic substance. In a further step, the quantity of the magnetic substance of the printing ink is reduced in at least a partial area of the printed-on printing ink. [00091 The printing ink comprises, mixed with a base ink for the printing method applied, such as relief printing, gravure printing, offset printing, screen printing, numeric printing, indirect printing, flexographic printing, thermoprinting, laser printing, inkjet printing, dot matrix printing, etc, a magnetic paste with para- and/or ferro-magnetic particles. The printing ink is therefore magnetizable and generates in the case of ferro-magnetic particles a magnetization which persists even without an external magnetic field and generates a so-called remanence flux density. The magnetic particles here can be hard- or soft-magnetic. The magnetization can be machine-detected by magnet sensors. [00101 The printed-on printing ink covers the data carrier at least partly, that is, the data carrier is partly or completely printed with the security feature. 100111 Subsequent to the printing of the magnetic printing ink, the quantity of the magnetic substance contained therein is reduced, at least in certain areas, by the magnetic particles being removed or erased. In this way, the magnetic polarizability, that is, the achievable magnetization, is decreased in the corresponding partial area. Thus, in the case of ferro-magnetic particles the remanence flux density is reduced. Preferably, the quantity of the magnetic substance is reduced to 10 to 50% of the original quantity. The quantity of magnetic substance, thus, after the reduction differs from both the quantity of magnetic substance before the reduction and from zero, said different quantities of magnetic substance being measurable with suitable sensors in each case. The data carrier manufactured by the manufacturing method according to J the invention correspondingly has a changed magnetic structure which subsequently is detectable. Due to this partial change of the magnetic property in at least a partial area of the printed-on magnetic printing ink, it is therefore provided a clearly distinguishable machine-readable security feature. The thickness of the applied print of the printed-on printing ink is preferably not changed by the reduction of the quantity of the magnetic substance. [00121 The printed-on magnetic printing ink can be present in the form of a single print element or in the form of a plurality of spatially separated print elements. The one or more print elements, here, can be formed all-over or as a grid. The partial area in which the quantity of the magnetic substance is reduced may then be a partial area of such a print element or in the case of a plurality of print elements may completely comprise one or more print elements. In this way, on the data carrier can be provided a changed magnetic structure, for example, in the form of alphanumeric characters and/or graphic elements. Through this form of intelligent magnetic coding, the security feature of the data carrier can be marked and individualized. 100131 The manufacturing method according to the invention thus provides a machine-readable security feature for a data carrier, the presence of which is not recognizable to the viewer, and thus also not to a potential forger, and which, consequently, is missing in forgeries. The security feature can be checked, however, with suitable checking devices which are available at least in banks or at a point-of sale, for example a cash desk. [00141 A further advantage of the magnetic properties used according to the invention is that these are not influenced by soilings of the data carrier and thus are superior to optical security features. [00151 The magnetic printing ink can be printed directly onto the data carrier or, for example, onto a carrier foil for the production of a transfer element which is subsequently applied to the data carrier. [00161 In a preferred embodiment of the manufacturing method according to the invention the reduction of the quantity of the magnetic substance is effected by 14 interaction of the printed-on printing ink with the radiation of an electromagnetic radiation source, in particular with the radiation of a laser. The magnetic particles of the magnetic paste which is part of the printing ink are highly suitable to be removed from the printed-on printing ink with the aid of such electromagnetic radiation. By the action of the electromagnetic radiation, the magnetic particles are preferably vaporized and/or thrown out. This happens already with a very low radiation power or laser power. [0017] Preferably, the base ink and the wavelength of the laser are chosen such that the base ink is transparent to light of the laser's wavelength, so that the base ink does not absorb the laser light or only to a limited extent. In this way, the magnetic particles can be selectively processed with the aid of the laser, while the base ink in the applied print is not changed or only to a limited extent. 100181 Preferably, as a radiation source there are used short-time pulse lasers, such as Nd:YAG or Nd: YVO 4 lasers with a wavelength of 1.064 p.m, which provide pulse lengths in the range of 1 to 50 nanoseconds. The use of pulsed short-time lasers contributes to avoiding undesired changes in the security feature and in the data carrier. By using a laser to reduce the quantity of the magnetic substance in the printed-on printing ink, there can be achieved a high spatial resolution of the partial areas with the changed magnetic property. This spatial resolution is determined by the size of the interaction range of the electromagnetic radiation and preferably corresponds to the size of the laser focus. 100191 The change of the magnetic properties may be accompanied by a color change that should be as inconspicuous as possible. The color change or the color alteration of the partial area with the changed magnetic property can be characterized with the aid of the perceptually adapted LAB color space. Here, any shade has associated thereto an unequivocal value triple L, A, B, the L-value being between 0 and 100 and the A- and B- values each being between -128 and +127. The color difference AE of two shades of color (L;, A,, B,) and (L 2 , A 2 , B 2 ) is calculated from the Euclidean distance VAL' + AAz + AB 2 , there being applicable AL = L, - L 2 , AA = A/ - A 2 and AB = B, - B 2 . In this perceptually adapted color space, a particular color difference AE stands for a certain difference in color of two shades that are subjectively perceived by a viewer. [00201 By the reduction of the quantity of the magnetic substance the shade of the printing ink preferably changes by a color difference of less than 25, preferably less than 15, 5, 2 or 1. With such a small color difference, the color change in the partial area in which the quantity of the magnetic substance has been reduced turns out to be visually small, so that the color change, even in comparison with areas in which the quantity of the magnetic substance has not been reduced, is hardly or not recognizable to the viewer. 100211 The color alteration can be diminished by a suitable choice of the parameters of the printing ink and/or of the electromagnetic radiation source. In general, the color alteration upon the reduction of the quantity of the magnetic substance turns out to be small, when the shade of the magnetic paste has an only small color difference compared to the base ink. [00221 In a preferred embodiment, the printed-on security feature and/or the partial area in which the quantity of the magnetic substance has been reduced is concealed by patterns and/or structures in the background print. Moreover, the partial area can also be overprinted in a further processing step, for example with effect pigments. Such a concealing is advantageous in particular with greater color differences and/or when the visual perceptibility of the partial area having the changed magnetic structure is to be reduced. 100231 In a further preferred embodiment of the invention, by the printing of the printing ink onto the data carrier there is produced a tactilely perceptible element. 100241 The printing here is preferably effected by gravure printing, such as for example the intaglio printing in which the engravings are introduced into the printing plate with the aid of a manually guided or machine-guided graver, or the halftone gravure in which recesses are etched into the plate. The thus produced gravure print elements can be tactilely checked easily and without aids, but are difficult to imitate from a technical point of view. Gravure printing provides many degrees of freedom to selectively influence the tactile perceptibility as well as the magnetic properties of the printed-on gravure print element. The engravings in the printing plate for receiving the magnetic paste of the printing inks, here, are optimized in view of the necessary signal strength of the magnet sensors used, for example through a sufficient dimensioning of the engraving in the printing plate with regard to depth and/or width. The smallest extent of the engraving amounts to at least 10 x 10 tm. Preferably, the engraving has a width of more than 100 pm, particularly preferably 1 to 3 mm. The minimum distance of a plurality of engravings in the printing plate can amount to 0 Pm. It preferably amounts to 500 pm, particularly preferably 1 to 10 mm. The flank angle of the engraving in the printing plate preferably amounts to 400 (in relation to the surface normal of the printing plate surface), so that the engraving depth amounts to about half the engraving width. The flank angle is determined for example by the corresponding angle of the graver for producing the engraving. The engraving depths are between 0 and 250 pLm, preferably between 0 and 120 pm and particularly preferably between 30 and 70 pm. Here, differently thick applied prints which result from differently deep engravings may interact different with the laser used for reducing the quantity of the magnetic substance. Because the near-surface magnetic particles of a thick applied print are stronger influenced by the incident laser radiation than the particles located lower. For increasing the tactile perceptibility of the security feature, its tactile area has a line structure with tactilely perceptible lines with a height of for example 100 pm. 100251 The use of the gravure line printing for producing the security feature permits the realization of tactile elements integrated in the print element, especially in the boundary area of the print element. The provision of tactile elements increases the forgery proofness, as these elements can be copied only with difficulty, and in particular not by means of a (color) photocopier, and moreover, can be easily checked via the tactile sense. [00261 In a further preferred embodiment of the invention there is printed at least one further printing ink onto the data carrier so as to produce a further part of the security feature. The further printing ink differs from the first printing ink in the quantity of the magnetic substance which the further printing ink contains upon printing, in the shade of the printing ink, and/or in the thickness of the applied print. 10027] The further printing ink differs from the first printing ink for example in the mixture ratio of employed base ink and magnetic paste, or in the employed base ink itself and/or the magnetic paste itself, the latter having, for example, magnetic particles with other magnetic properties. In particular with the printing by gravure printing, the thickness of the applied print can be easily varied via the engraving depth of the printing plate. In addition, a plurality of magnetic pastes may be combined in one printing ink. Thus, a multitude of degrees of freedom are provided so as to confer to the printed-on printing ink the desired shade and the desired magnetic properties. In particular, already the thickness of the applied print influences the surface-related quantity of the magnetic substance in the security element and therefore the magnetization or the (remanence) flux density of the applied print. Since in gravure printing there are usually used transparent inks, via the ink layer thickness there can also be set the shade value. 10028] The printing of the further printing ink can be effected in one processing step together with the printing of the first printing ink. In particular, a multi-color print is possible. Here, the further printing ink may not only have magnetic properties different from the first printing ink, but one can also do completely without the admixture of a magnetic paste, so that already upon the printing of the various printing inks a structuring of the security element's magnetic properties is possible. Preferably, structures can be printed on, which are alternating magnetic and non-magnetic. [00291 In a further advantageous embodiment, the magnetic properties of the different printed-on printing inks are individualized by reducing the quantity of the magnetic substance in at least a partial area of the further printing ink. [0030] This results in further degrees of freedom for the individualization of the data carrier and for the design of the desired security feature. Preferably, the shade and/or the quantity of the magnetic substance of the plurality of printed-on printing inks is chosen such that after the individualization there are areas with different magnetizations (with regard to strength and/or kind of magnetization) but the same 0 shades, so that the areas having measurably different magnetic properties are visually hardly or not distinguishable. 100311 Advantageously, the contours of the area of the printing ink and/or of the partial area in which the quantity of the magnetic substance is reduced are chosen such that the area of the printing ink and/or the partial area are detectable by machine to a desired extent with a magnet sensor. A magnet sensor generates a detection signal at the transition between areas with different magnetic flux densities, for example at the transition between an area without magnetic substance and an area with magnetic substance, or also between the area of the printing ink and a partial area with a reduced quantity of magnetic substance. The strength of the detection signal depends on the time-related gradient of the magnetic flux density at the magnet sensor, so that a stronger detection signal is generated when the security feature is moved for example with greater speed past the magnet sensor, and in particular when on the security feature there is present a sharp or fast transition between areas with different magnetization, in other words, when a strong location-related gradient of the quantity of the magnetic substance is present on the data carrier. Such a sharp transition is produced for example by rectilinear boundary contours of the different areas of the security element, which preferably extend transverse to the direction of detection, that is, transverse to the direction in which the data carrier is moved, in relation to a magnetic sensor of a corresponding checking device, upon the detection of the magnetic properties for example in a checking process. This detection direction, in general, is already known upon the manufacturing of the data carrier and, in general, equals to the direction of one of the edges of the data carrier or of the security element. Such an orientation of the edges leads to a high detection signal in the magnet sensor and thus reduces, on the one hand, the necessary quantity of magnetic particles in the printing ink and, on the other hand, the necessary detection sensitivity of the magnet sensor, which permits that the security feature and its different areas can be detected with low effort and high reliability of detection. [00321 If, however, there is desired an as low as possible detection signal of the magnet sensor at the transition between areas with different magnetization, there will preferably be produced a slow transition, that is, a wide transition area with a small 7 location-related gradient of the quantity of the magnetic substance at the transition, and the transition is concealed by for example the intensity of the electromagnetic radiation, with which the quantity of the magnetic substance is reduced in the partial area, being changed continuously or in steps in the boundary area of the partial area. In this way, during the step of the reduction of the quantity of the magnetic substance, for example via the intensity of the electromagnetic radiation, there can be changed the strength of the later detection signal of the magnet sensor, and thus the security feature of the data carrier can be additionally individualized. The individualization is preferably supported by a suitable choice of the contour of the area or the areas of the printing ink having the magnetic particles. [00331 Advantageously, the quantity of the magnetic substance in the at least one partial area is not reduced all-over, but only in a grid-like manner. The basic idea here is that the location-related resolution of the magnet sensor is usually lower than the location-related resolution of the electromagnetic radiation used to reduce the quantity of the magnetic substance, for example of the laser focus. In this way, for example, there can be produced a sharp transition well detectable for the magnet sensor, while the shade of the printing ink in this partial area is changed to be visually not perceptible or only slightly perceptible. For this, the width of the interaction range of the electromagnetic radiation is preferably chosen such that within the partial area there is produced a visually barely perceptible grid pattern. The grid preferably comprises dots or lines with suitably chosen patterns, in particular with variable grid spacings and/or grid rulings. In a particularly preferred embodiment, the partial area has grid lines which lie in the direction of the detection direction, since in this way the position of the grid lines, in relation to the magnet sensor, is not changed during the detection, and therefore the occurrence of an undesired detection signal is excluded. [00341 In a further preferred embodiment, the quantity of the magnetic substance is not reduced in the entire applied print of the printing ink but merely at its top side. In this way, the quantity of the magnetic substance is reduced only in a small segment of the applied print, whereby the shade of the applied printing ink is only slightly visually changed. Such a reducing of the quantity of the magnetic substance in only a near surface area can be very easily performed with a gravure print element whose applied I V print has a significant height, in particular with a tactile element. Preferably, this near surface reducing at the same time is performed in a grid-like manner, which further reduces the visual differentiability of the partial area from the printing ink area whose quantity of magnetic substance is not reduced. 100351 Preferably, the laser used to reduce the quantity of the magnetic substance is also used for introducing further markings, for example individualizing codings, into at least one further security feature, for example into a foil element and/or a security thread, of the data carrier. [00361 By means of the above-described method there can thus be manufactured a data carrier having a printed-on security feature which has a first and a second partial area with the same print layer thickness and the same printed-on printing ink, said first partial area containing a first quantity of a magnetic substance and the second partial area containing a second, lower quantity of the magnetic substance that is reduced compared to the first partial area. Further partial areas of the security feature may have other print layer thicknesses, other shades, other printing inks and/or different magnetic substances or quantities of substances. [00371 The security feature can be designed, as mentioned, as a spatially coherent, continuous application of ink, that is, as an individual print element. The first and second partial areas then form partial areas of the individual print element. The security feature may also consist of a plurality of print elements spatially separated from each other. In this case, the first and second partial area comprise, for example, partial areas of the various print elements or, preferably, completely comprise one or more different print elements. [00381 The various partial areas of the security feature can be manufactured in only one single printing step. With the aid of a suitable postprocessing step, preferably in the form of an action of a laser, the magnetic properties of the printed-on printing ink can be selectively changed in certain areas. Thus, a data carrier having an individualized security feature can be provided.
1 1 [0039] Other embodiments and advantages of the invention are explained by way of example with reference to the Figures. [00401 Fig. 1 shows a bank note with a printed security feature in the form of an individualized matrix; 10041] Fig. 2 shows a bank note with a printed security feature, comprising an alphanumeric character; [00421 Fig. 2A-C show a printed security feature, comprising a numbering which was lasered with a from Fig. 2A to Fig. 2C increasing laser power; 10043] Fig. 3A, 3B show a printed security feature in the form of a matrix; [0044] Fig. 4A, 4B show the veiling of a previously distinct edge; 100451 Fig. 5 shows the distinct forming of a previously veiled edge; [0046] Fig. 6A, 6B, 6C show different grid patterns for reducing the magnetic pigment quantity; 100471 Fig 7 shows a magnetic detection signal, and [0048] Fig. 8 shows a perspective view of a gravure print element. 100491 The invention is now explained in more detail by the example of a bank note. For this, Figures 1 and 2 each show, schematically, a bank note 1 with two security features: a security strip 2 and a printed-on security feature 3. 100501 In a preferred exemplary embodiment of the manufacturing method, the security feature 3 is printed onto the data carrier by means of intaglio printing. The printing ink to be printed on is composed of a per se known intaglio printing ink as a base ink and of a magnetic paste or of a different magnetic printing ink which forms a portion of 10 to 60% of the printing ink to be printed on. In the preferred exemplary embodiment the magnetic base ink consists of the following components: I , - Magnetic pigment BASF 345 (hard iron) 35.0%; - Binder intaglio printing 67 0109/16 (GSI) 37.0%; - Chalk (not coated) 10.0%; - Anti set-off paste 67 0113 (GSI) 6.0%; - Anti set-off paste 67 0114 (GSI) 6.0%; - Mineral oil 190 - 240*C I.B.P. 2.0%; - Micronized PE wax 2.0%, and - Drier 67 0141 (GSI) 2.0%. 100511 In the printed-on printing ink, the portion of magnetic pigment, that is, the quantity of the magnetic substance, therefore amounts to between 5% and 20%. The indications of quantity refer to the weight (weight percent). [00521 The magnetic pigment, the binder and the chalk form that portion of the magnetic paste which is to be abraded. The other components form the so-called mixing portion of the magnetic paste. The portion to be abraded is dispersed by a three-roll mill or a bead mill. [00531 The coercitive field strength of the magnetic pigment should be between 18 and 40 kA/m. Preferably, the isometric magnetic pigment BASF 345 is used, which has a coercitive field strength of 21 kA/m (= 265 Oe). 100541 As a base ink for the printing ink, in the preferred exemplary embodiment, a yellow intaglio printing ink is used. But there can also be used intaglio printing ink of any other shade, provided that the intaglio printing ink is suitable for a mixing with magnetic paste. The intaglio printing ink and the magnetic paste generally have different shades, so that via their mixture ratio not only the magnetic properties of the printed-on printing ink can be influenced, but also its shade. In the preferred exemplary embodiment, the intaglio printing ink is yellow and the magnetic paste is olive, so that with an increasing portion of the magnetic paste the resulting printing ink I j becomes darker and darker. Furthermore, the magnetic paste can be changed according to the requirements regarding the magnetic properties, and it is also possible to mix a plurality of different magnetic pastes with an intaglio printing ink to form a printing ink. [00551 Preferably, there can also be used magnetic pastes which are not olive colored, dark-colored or black, but which are as bright as possible or white. This has the advantage that they do not or only slightly change the shade of a bright intaglio printing ink. Particularly preferred, the magnetic pastes are transparent to electromagnetic radiation in the infrared wavelength range. [0056] Subsequently, the security element with the chosen magnetic properties, in particular with the chosen quantity of the magnetic pigment, is printed onto the data carrier. The remanence flux density that can be obtained by the printing may be below the scale of the natural terrestrial magnetic field (approx. 50 pT) and, for example, amounts to 10 ptT. The necessary flux density of the applied print is determined by the checking method, in particular the sensitivity of the magnet sensors used therefor. 100571 For example, with the gravure printing, an application of ink of approx. 8 g/m 2 can be produced. 100581 Subsequently, the printed-on printing ink is processed with a laser. In the preferred exemplary embodiment, for this a Nd:YAG or a Nd:YVO 4 short-time laser is used with a continuous wave power in the range of I to 10 watts, for example 6 watts, a pulse frequency of up to 100 kHz and a surface-related energy of 1 to 5 J/cm 2 The pulse length of the laser pulses is less than 50 ns, preferably less than 20 ns, or even less than 1 ns. 100591 The mentioned laser types have a wavelength of approx. 1064 nm which is not absorbed by the yellow intaglio printing ink of the printing ink. When other intaglio printing inks are used, possibly, a different laser wavelength must be chosen, so that this lies in a range in which the intaglio printing ink does not or only slightly absorb. In this way, the laser interacts over the entire layer thickness of the applied IIt printing ink, which, at a high laser power, can be recognized by traces of dense smoke on the top and bottom side of the printed-on printing ink. [00601 The laser parameters such as power, pulse length, pulse frequency, duration of interaction and spot size of the laser, that is, its focusing, are adjusted on the one hand to the various components of the printed-on printing ink and on the other hand to the desired result. [00611 Fig. 3A shows a printed security feature which consists of a matrix of 7 by 3 equally printed print elements. These can be print elements that are printed all-over or printed as a grid, for example a line grid printed by gravure line printing. In the matrix, the left column and the top and the bottom line of the print elements were excluded from the laser treatment, that is, the print elements that lie outside the area A. After the printing the print elements located in the area A were processed with a laser, print elements lying in one line side by side being processed in the same manner. All print elements within the area A were processed with the same laser power, but the interaction period with the laser grows within a column increasing from top to bottom. To the right of the column there is indicated the color difference, resulting from the laser treatment, compared to an unprocessed print element. As it appears from Fig. 3A, the color difference increases with increasing interaction duration, that is, with the number of laser pulses which have acted upon the print element. In other words, with the quantity of removed magnetic substance there does not only grow the difference in magnetization and/or remanence flux density compared to an untreated print element, but also the color difference. Similar results are obtained when the processing is effected with different laser power and the same number of laser pulses. 100621 Typically, the quantity of magnetic pigments in the applied print is reduced by the laser treatment to 10 to 50% of the original value, so that the remanence flux density goes down, for example, from 10 JT to values of between I and 5 pT, for example, 2, 3 or 4 JT. [00631 In Fig. 3B, there is shown a further security feature, which has the same spatial matrix structure as the security feature shown in Fig. 3A. The applied printing ink, however, differs in the mixture ratio of the intaglio printing ink used and the magnetic paste. The portion of olive magnetic paste, compared to the yellow intaglio printing ink, has been reduced here, which results in a brighter shade of the initially printed-on printing ink compared to the exemplary embodiment shown in Fig. 3A. In the exemplary embodiment shown in Fig. 3B there was used, moreover, a laser intensity increased by the factor 4, whereby through different laser powers different portions of magnetic particles can be removed in the applied print. In the exemplary embodiment shown in Fig. 3B, there is produced a detectable difference between the magnetic signal of a processed and of an unprocessed print element already at a lower color difference than the one shown in the exemplary embodiment of Fig. 3A. 10064] With the technique shown in Fig. 3A and 3B, codings and/or individualizations can be introduced into security features consisting of a plurality of print elements, as this is outlined in Fig. 1. Alternatively, also other markings, such as alphanumeric characters and/or graphical symbols, can be introduced into a continuous print area, as this is outlined in Fig. 2. In Figures 1 and 2, reference number B denotes the partial areas processed with the laser. 100651 The introduced individualization for example may relate to a predetermined pattern, may serve to code a numbering, or may denote a denomination, for example of a bank note. [00661 The Figures 2A to 2C show a particularly preferred exemplary embodiment, in which the security feature 3 consists of a colored ink into which was mixed a certain quantity of a magnetic pigment. Into this security feature 3 is introduced a reference sign B in the form of a numbering by means of a laser. The reference sign B here is formed as a negative writing, that is, the laser impinges on a large area of the security feature 3, the numbering being produced by reducing or switching off the laser power. Figures 2A to 2C each show in their upper part the security feature 3 with introduced reference sign B and in their lower part the reference sign B which is merely introduced into the substrate of the bank note 1. [00671 In the chosen exemplary embodiment, the impinged laser power increases from Fig. 2A to 2C. Here, ILU - in Fig. 2A, the laser power is chosen so low that the laser does not or hardly recognizably change or blacken the substrate of the bank note I (Fig. 2A, bottom). If the laser strikes the security feature 3 with the same laser power, however, the magnetic pigments will be changed or brightened, so that the area of the security feature 3 impinged with the laser appears bright compared to the areas not impinged by the laser (Fig. 2A top). The numbering appears in the shade of the areas not impinged by the laser and is therefore recognizable as a dark writing compared to the bright areas impinged with the laser, that is, the numbering appears as a positive writing. - in Fig. 213, the laser power is chosen such that the laser recognizably changes or blackens the substrate of the bank note 1 (Fig. 2B bottom). If the laser strikes the security feature 3 with the same laser power, the magnetic pigments will be changed or brightened just as in Fig. 2A, but the laser power is adjusted such that through the simultaneous changing or blackening of the substrate the area of the security feature 3 impinged with the laser appears just as bright as the areas not impinged by the laser (Fig. 2B top). This means, that the change of the magnetic pigments and the change of the substrate showing through the ink cancel each other out to a viewer. The area impinged with the laser, thus, is not recognizable, just as the numbering in the security feature 3. - in Fig. 2C, the laser power is chosen so high that the laser greatly changes or blackens the substrate of the bank note 1 (Fig. 2B bottom). If the laser strikes the security feature 3 with the same laser power, the magnetic pigments will be changed or brightened just as in Fig. 2A or Fig. 213, but through the simultaneous great changing or blackening of the substrate the area of the security feature 3 impinged with the laser appears darker or black compared to the areas not impinged by the laser (Fig. 2C top). This means that the substrate's change or blackening showing through the ink predominates over the change of the magnetic pigments. The numbering appears in the shade of the areas not impinged by the laser and is therefore recognizable as a bright writing against the dark areas impinged by the laser, that is, it appears as a negative writing.
1l [0068] In a further preferred exemplary embodiment, both the printed-on printing ink as well as its partial areas processed with the laser integrate into the rest of the design of the data carrier, for example into a background print or into a subsequent overprinting, as a result of which the security feature and in particular its partial areas processed with the laser are concealed. [00691 In the Figures 4A and 4B, on the basis of two variants, there is shown the veiling of a transition between two areas of a security element. For this, there is produced a spatially slow change of the magnetic pigment quantity between an area C with applied printing ink having magnetic pigments and a partial area B having a reduced quantity of magnetic pigments. In each of the upper parts of the two Figures there is shown a top view onto the security feature in which the partial area B is formed rectangular in the surrounding area C. In the lower part of the two Figures, there is outlined the intensity of the laser radiation used for reducing the quantity of magnetic pigments. The left edge of each of the partial areas B, here, is a so-called resolved edge or a veiled transition, which upon the detection with the magnet sensor is to generate no or only a low signal, the detection direction here being parallel to the x-direction. For this, the full intensity of laser radiation, which is necessary for reducing the magnetic pigments by the desired quantity, is set not until a certain distance away from the left boundary of the partial area B. In between, the intensity of the laser radiation is increased in stages (Fig. 4A) or gradually (Fig. 4B) with growing distance away from the boundary of the partial area B, which leads to the desired spatially slow change of the magnetic pigment quantity in the direction of the x-axis. [00701 Using the same technique of changing the intensity of the laser radiation with growing distance away from a boundary, there can also be converted an at first sharp edge or a spatially fast transition, as it results for example from a directly adjacent printing of two printing inks having different magnetic pigment quantities, into an indistinct, veiled edge with a broad transition area, which generates no or an only low detection signal. [00711 In Fig. 5, there is shown the opposite case. An area C having a curved edge is printed on with printing ink. In this way, through the printing there is created a 10 indistinct, veiled edge, that is, the magnetic pigments contained in the printing ink generate an only low detection signal, since the average magnetic pigment quantity in dependence on the position on the x-axis only slowly increases within the area of the curved edge. This indistinct, veiled edge can be converted into a sharp, distinct edge with a strong detection signal by adjusting, with the aid of laser radiation in the area of the curved edge, the quantity of magnetic pigments in the area C to the quantity of magnetic pigments in the surrounding area. In the simplest case, in the surrounding area there are not present any magnetic pigments and in the area of the curved edge of area C the magnetic pigments are completely removed in order to produce the sharp edge. [00721 In the Figures 6A, 6B and 6C there are schematically shown various grid types as they can be used to produce a partial area B with reduced magnetic pigment quantity. The displayed grid dots and grid lines here represent the interaction range of the laser radiation. The interaction range, ideally, is very narrow. The grid pattern, the grid spacing and the grid ruling here are chosen in accordance with the requirements and may vary over the partial area B. 100731 In the upper part of Fig. 7 there is schematically shown a plan view onto a security element. This has an area C with an applied printing ink with magnetic pigments and a partial area B with the same printing ink but with reduced magnetic pigment quantity, the magnetic pigment quantity having been reduced with the aid of a line grid. In the bottom area there is shown the detection signal U of a magnet sensor, the detection direction being in the x-direction. The grid spacings of the line grid in partial area B lie below the spatial resolving power of the magnet sensor, for the reason of which, despite the use of a grid and the thus not all-over reduced magnetic pigment quantity in partial area B, there is a sharp edge at the boundary line D between area C and partial area B, which generates a strong detection signal of the magnet sensor. A further sharp edge lies at the right boundary line E of area C. This exemplary embodiment is suitable for the case of a small amount of ink per area and is particularly suitable for bright printing inks.
17 100741 In Fig. 8 there is shown a gravure print element in perspective view which consists of a printing ink having magnetic pigments. Here, only in a near-surface partial area B the magnetic pigment quantity is reduced. In the rest of area C of the gravure print element the magnetic pigment quantity is not reduced. A possible color alteration of the printing ink of the gravure print element here can take place only in the small partial area B, which strongly reduces the visual perceptibility of this area B. 10075] During the manufacturing, with the laser there can also be processed, besides the gravure print element 3, further security features, such as the security thread 2 schematically shown in Figures 1 and 2, other foil elements and other security features suitable for a laser processing.