EP1904312B1 - Data carrier and method for the production thereof - Google Patents

Description

The invention relates to a data carrier, in particular a valuable document or a security paper, with a substrate and a coating applied to the substrate, in which by the action of laser radiation markings in the form of patterns, letters, numbers or images are introduced. The invention also relates to a method and a device for producing such a data carrier.

Security documents, such as banknotes, stocks, bonds, certificates, vouchers, checks, tickets and the like, are usually provided with an individualizing identifier, such as a serial number. To increase safety, this number plate is often applied several times to the value document. For example, banknotes are double-dotted so that each banknote half is uniquely identifiable. The two numbers are usually the same.

Identity cards have long been provided with laser marking with an individual identification. When marking by laser engraving, the optical properties of the card material in the form of a desired marking are irreversibly changed by suitable guidance of a laser beam. For example, in the document DE 30 48 733 A1 an identity card with applied information is described, which has on a surface of different colored and stacked layer areas, which are at least partially interrupted by visually recognizable personalization data.

Out EP 0 372 274 A2 is a recording medium, in particular an identity card, with overlapping, color-contrasting layers known, wherein under a first laser-beam-transparent ink layer a thermally degradable second layer is arranged by laser beam action. As a result of the conversion of the laser beam energy in the second layer and the associated thermal degradation of this layer, the first color layer is also locally removed and information is displayed which is generated by local ablation of individual layer areas exposing deeper, differently colored layer areas.

This means that the first layer is penetrated by the laser beam, without showing any significant effect, and only in the underlying second layer whose material is thermally degraded by the penetrating laser beam. The thermal degradation of the material of the second layer causes a sudden increase in the internal pressure of the card material at the relevant point, with the result that the overlying first layer is not able to resist the high pressure and is blasted off as it were.

Central banks and banknote designers are calling for more space for security features on banknotes. The numbering competes as well as the individualization by laser inscription with other security features to the available space on the banknote. The problem is compounded by the upgrading of existing banknote series, where the design is essentially not to be changed.

A conventional numbering requires a white or at least light background, which must also not be executed in intaglio, since otherwise color residues can get into the digit drives and affect their function. Due to the usual Passerschwankungen therefore a relatively large space for the numbering must be maintained.

Even with a laser numbering a certain place in the design must be provided specifically for the numbering, if other printing components or security elements should not be disturbed, since in the laser marking of stacked layer sequences usually with the absorbing ink layers and overlying non-absorbent overprints with be removed.

Proceeding from this, the present invention seeks to propose a data carrier of the type mentioned, which can be provided in a simple manner with an individual identification with high security against counterfeiting. In particular, the label should take up little space on the disk and can be easily integrated into existing designs or print images.

This object is achieved by the data carrier and the production method having the features of the independent claims. Further developments of the invention are the subject of the dependent claims.

1. a) ein vorbestimmtes Laserstrahlungsspektrum ausgewählt,
2. b) ein Substrat des Datenträgers bereitgestellt,
3. c) auf das Substrat des Datenträgers eine für die Laserstrahlung absorbierende Schicht aufgebracht,
4. d) über die absorbierende Schicht eine für die Laserstrahlung zumindest teilweise durchlässige Schicht aufgedruckt,
5. e) das Substrat während oder nach dem Aufbringen der zumindest teilweise durchlässigen Schicht verpresst, und
6. f) die aufgebrachte Beschichtung mit Laserstrahlung des ausgewählten Laserstrahlungsspektrums beaufschlagt, um die visuell erkennbaren Kennzeichnungen zumindest in der absorbierenden Schicht zu erzeugen.

According to the invention, in a method for producing a data carrier with a visually recognizable marking in the form of patterns, letters, numbers or images

1. a) a predetermined laser radiation spectrum selected,
2. b) providing a substrate of the data carrier,
3. c) a layer absorbing the laser radiation is applied to the substrate of the data carrier,
4. d) a layer which is at least partially permeable to the laser radiation is printed over the absorbing layer,
5. e) compressing the substrate during or after the application of the at least partially permeable layer, and
6. f) is applied to the applied coating with laser radiation of the selected laser radiation spectrum to produce the visually recognizable markings at least in the absorbent layer.

Without being bound by any particular explanation, as currently understood, the high pressure of compressing the substrate provides a particularly good bond between the at least partially transparent ink and the substrate, so that the absorbent layer can be removed in the subsequent labeling step f) without the need for an explanation to destroy partially transparent print layer.

The custom marking can thus, as usual and expedient, only be introduced at the end of the various print passes required for the production of the data carrier. At the same time, due to the partially permeable layer which is still arranged above the marking, the appearance of the viewer appears to the observer as if the marking had already been introduced in a work step at the beginning of the production chain. This allows designs with a visually appealing overall impression and leads to a high security against counterfeiting, since such an individual marking can not be adjusted by a subsequently applied printing layer.

In a preferred variant of the method, the at least partly permeable layer is applied in step d) by intaglio printing and the substrate is pressed in this process. According to another, likewise advantageous variant, the substrate is blind-embossed after the application of the absorbent layer and the at least partially permeable layer. Another preferred way to compress the printed substrate is to subject the substrate to a calendering step after the application of the absorbent and the at least partially permeable layer.

In all process variants, the at least partly permeable layer in step d) is advantageously printed in the form of fine structures, in particular in the form of guilloches, microtext, graphic elements or the like.

The absorbent layer is preferably printed in step c) and is particularly preferably printed by screen printing, for example with a metallic effect color, such as a silver or gold color. Alternatively, in step c), a coated or uncoated film can also be applied as an absorbing layer. For example, as the coated film, a colored film not absorbing even at the selected laser wavelength, which is provided with a thin metal layer such as a vapor-deposited aluminum layer, may be used. In all variants, it is particularly appropriate to form the absorbent layer in step c) as a solid surface.

According to an advantageous development of the invention, the absorbent layer in step c) can also be applied in subregions with different printing methods or printing parameters, so that the subregions differ from the laser radiation in the laser application in step f) to be influenced. For example, a first portion of the absorbent layer can be imprinted in intaglio printing and a second portion in the nyloprint process. In the case of the marking in step f), the second subregion is then removed together with the underlying absorbent layer, while the first subregion remains through the compression.

As mentioned, the laser parameters in step f) can be selected such that the at least partially transparent layer remains completely intact during laser application. However, it is also possible to change the laser parameters during the application in step f) in order to partially let the partly transparent layer pass and partially remove it.

Furthermore, embossings, in particular embossings obtained without ink guide, can be obtained by a suitable choice of the laser parameters in the application in step f), whereby the safety of the overall element is further increased. Alternatively, the laser parameters may also be changed during the application in step f) in order to partially allow the partial removal of the embossings in the coating.

The application of laser radiation in step f) is advantageously carried out from the front side of the substrate, ie from the substrate side, on which the absorbing layer and the partially permeable layer are applied. However, it is also possible to carry out the laser application from the back of the substrate. In this case, it is advantageous if the substrate has the lowest possible absorption at the laser wavelength.

The absorbent layer and the at least partially permeable layer can be applied to each other completely or partially overlapping. In front and / or after the exposure to laser radiation, a protective layer can furthermore be applied.

The selection of the laser radiation spectrum in step a) is typically carried out by selecting a suitable laser wavelength. As the laser source, an infrared laser in the wavelength range of 0.8 μm to 3 μm, in particular a Nd: YAG laser, is advantageously used for the identification in step f). The laser beam is expediently passed over the substrate during the application at a speed of more than 1 m / s, preferably of more than 4 m / s, particularly preferably of more than 10 m / s, in order to take account of the high processing speeds in securities printing wear.

The invention also includes a data carrier of the type mentioned above, the coating containing a laser radiation absorbing layer and disposed over the absorbent layer, for the laser radiation at least partially transmissive print layer and wherein the printed substrate during or after the printing of the at least partially permeable layer is compressed.

In a preferred embodiment, the at least partially transparent layer is formed by a gravure printing layer. In another, likewise preferred embodiment, the at least partially permeable layer contains a color mixture which has a mixture component absorbing the laser radiation and a mixture component transparent to the laser radiation.

As explained in detail below, the absorbing mixture component can be bleached under the action of the laser radiation, for example, vaporized, changed in their reflective properties or converted by a chemical reaction into a material with different optical properties. But it is also possible that the absorbing mixture component undergoes no recognizable changes to the naked eye when exposed to laser radiation. The color mixture preferably contains optically variable color pigments, in particular optically variable liquid crystal pigments or a transparent intaglio printing ink as the mixture component transparent to the laser radiation, and, for example, optically variable interference layer pigments for the absorbing mixture component. Other color components that 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 absorbent mixture component.

It is also possible that the labeling in step f) does not change the optical properties of the absorbent mixture component, but rather that the color mixture contains a color component which interacts with the absorbent mixture component and whose optical properties are indirect, namely by absorption of the laser radiation in the absorbing layer Mixture component, in particular the resulting local temperature elevation in the coating, irreversibly changed.

As such a cooperating color component, in particular, even non-absorbing color components, such as certain intaglio inks, luminescent colors or luminescent pigments, luster pigments or thermochromic inks are possible. As absorbent mixture component For example, the color mixture contains carbon black, graphite, TiO ₂ or an infrared absorber.

The at least partially permeable layer is preferably printed in the form of fine structures, in particular in the form of guilloches, microtext, graphic elements or the like.

By contrast, the absorbent layer is expediently designed as a solid surface. It may in particular be formed by a printing layer, for example a screen printing layer or by a coated or uncoated film. In a further variant of the invention, the absorbing layer contains a color mixture which, in the manner described above, has a mixture component absorbing the laser radiation and a mixture component transparent to the laser radiation.

The coating has optically variable properties according to an advantageous embodiment. It may also contain one or more protective layers applied before or after the laser application. The absorbent layer and the at least partially transmissive layer may completely or partially overlap one another in all embodiments.

Below the absorbent layer, the coating can contain a further layer which is at least partially permeable to the laser radiation and which is exposed by the marking in method step f). The further layer can contain, for example, visually recognizable features in the region of the markings, by certain viewing conditions, such as UV illumination, activatable features and / or machine-readable features.

As the substrate of the data carrier, a paper substrate such as a cotton paper or a plastic substrate such as a PET or PP film may be used. Advantageously, the data carrier represents a security element, a banknote, a value document, a passport, a passport card, a document or another product protection agent.

The invention also includes a printing machine with a laser system for carrying out the method described above. The laser system is arranged over a printing cylinder of the printing press to pressurize the data carrier to be marked on the printing cylinder with laser radiation. Preferably, the laser system is designed for the vibrations occurring in the printing press during printing. This can for example be done by the laser system is formed with a supporting frame, which is designed according to a finite element method analysis of the vibrations occurring so that the laser system carries out the vibrations of the printing press, without being rocked.

The laser system advantageously contains at least one identification laser with a horizontally arranged laser resonator, which is connected via a beam tube to a scan head for deflecting the laser beam. In expedient embodiments, the laser system contains more than one marking laser, for example 2, 4 or 6 marking lasers.

Preferably, the laser system is vertically movable between one or more working positions for laser loading of the data carrier and a maintenance position, wherein the printing cylinder and subsequent inking units of the printing press are accessible in the maintenance position.

The laser system further advantageously has a shielding chamber arranged directly above the printing cylinder, which shields the laser radiation and is designed for the extraction of the gases and dusts resulting from the marking.

Further exemplary embodiments and advantages of the invention are explained below with reference to the figures, in the representation of which a representation true to scale and proportion has been dispensed with in order to increase the clarity.

Fig. 1

eine schematische Darstellung einer gekennzeichneten Banknote nach einem Ausführungsbeispiel der Erfindung,

Fig. 2

einen Querschnitt durch die Banknote von Fig. 1 entlang der Linie II-II im Bereich der Kennzeichnung,

Fig. 3

eine Aufsicht auf die Kennzeichnung einer Banknote nach einem anderen Ausführungsbeispiel der Erfindung,

Fig. 4

eine Aufsicht auf die Kennzeichnung einer Banknote nach einem weiteren Ausführungsbeispiel der Erfindung,

Fig. 5

einen Querschnitt durch die Banknote von Fig. 4 entlang der Linie V-V im Bereich der Kennzeichnung,

Fig. 6 und 7

eine Aufsicht auf bzw. einen Querschnitt durch ein Wertdokument nach einem weiteren Ausführungsbeispiel der Erfindung,

Fig. 8 bis 10

Querschnitte von Banknoten nach weiteren Ausführungsbeispielen der Erfindung,

Fig. 11

eine schematische Darstellung eines Vektorlaserbeschrifters zur erfindungsgemäßen Kennzeichnung von Datenträgern,

Fig. 12

eine schematische Darstellung von Vektor-Laserbeschriftern zur Beschriftung eines Wertpapierbogens,

Fig. 13

eine schematische Ansicht einer Druckmaschine, die mit einer erfindungsgemäßen Laseranlage zur Kennzeichnung von Banknoten und dergleichen versehen ist, und

Fig. 14

die Laseranlage der Fig. 13 im Querschnitt.

Show it:

Fig. 1

a schematic representation of a marked bill according to an embodiment of the invention,

Fig. 2

a cross section through the banknote of Fig. 1 along the line II-II in the field of marking,

Fig. 3

a plan view of the marking of a banknote according to another embodiment of the invention,

Fig. 4

a plan view of the marking of a banknote according to a further embodiment of the invention,

Fig. 5

a cross section through the banknote of Fig. 4 along the line VV in the area of marking,

6 and 7

a top view or a cross section through a document of value according to a further embodiment of the invention,

Fig. 8 to 10

Cross sections of banknotes according to further embodiments of the invention,

Fig. 11

a schematic representation of a Vektorlaserbeschrifters for labeling according to the invention of data carriers,

Fig. 12

a schematic representation of vector laser markers for labeling a security sheet,

Fig. 13

a schematic view of a printing machine, which is provided with a laser system according to the invention for the identification of banknotes and the like, and

Fig. 14

the laser system of Fig. 13 in cross section.

The basic principle of the invention will now be described first on the basis of Figures 1 and 2 explained using the example of a banknote. Fig. 1 shows a schematic representation of a banknote 10, on the front side of a coating 12 is applied, in which by the action of an infrared laser beam, an identification 14, in the embodiment in the form of the digit sequence "1234" is introduced. Fig. 2 shows a cross section through the banknote 10 along the line II-II of Fig. 1 in the area of labeling 14.

As in synopsis of Figures 1 and 2 1, the coating 12 applied to the paper substrate 20 of the banknote 10 contains two partial layers: a first layer 22 which absorbs the laser radiation of the infrared laser used for identification and a second layer 24 which is transparent to the laser radiation used.

When the laser is applied, the laser radiation incident from the front side of the substrate passes through the transparent second layer 24 and generates the marking 14 in the absorbent first layer 22. Depending on the material used, the absorbent layer 22 can be locally bleached, evaporated, for example, in its reflection - or absorption properties changed or converted by a chemical reaction in a material with different optical properties.

The second, transparent layer 24 also remains in the region of the marking 14. This is inventively achieved in that the substrate 20 is compressed during or after the printing of the second layer 24. As a result of the pressure occurring in the present case, a particularly stable connection of printing layer 24 and substrate 20 is produced, which makes it possible to introduce a marking into the absorbing layer 22 without destroying the transparent layer 24.

The pressing of the substrate is in the embodiment of Figures 1 and 2 achieved in that the transparent layer 24 is printed by intaglio printing with a high pressure of, for example, 50,000 kPa. The intaglio technique allows for a relatively thick paint application compared to other common printing techniques. The thick ink layer 24, together with the partial deformation 26 of the paper surface, which comes about when the paper is pressed into the engraving of the printing plate, can also be easily felt manually by the layman and can thus easily be recognized as an authenticity feature by virtue of its tactility.

A more complex embodiment is in Fig. 3 which shows a plan view of a banknote 30 designed according to the invention. For identification For example, the banknote 30 uses a Nd: YAG laser with a wavelength of 1.064 μm, as described in detail below.

In the production of the banknote 30, a silver-colored effect color layer 32 in the form of a coin is applied to the banknote substrate, first by screen printing, over the whole area. The effect color layer 32 forms the layer absorbing the selected infrared laser radiation. In the effect color layer is then with a intaglio printing plate in Fig. 3 only schematically illustrated portrait 34 blind embossed and a guilloche-shaped edge pattern 36 imprinted in intaglio.

The marking area is then lasered from the printed side of the banknote 30 and a desired marking 38, for example in the form of a serial number or another individualizing identifier, is produced in the effect layer 32. In the exemplary embodiment, the identification 38 is shown schematically as a number sequence "12345". Due to their high absorption, the silver effect color 32 is completely removed in the irradiated area 38, so that the marking in the incident light and especially in the transmitted light comes out in high contrast.

Furthermore, in the areas 38, the intaglio printing ink of the edge pattern 36 lying above the effect layer 32 and transparent to the laser radiation can be recognized, which was not destroyed during the laser application due to the good connection of printing ink and paper resulting from the high pressure. In this way, an individual identification 38 is created in the printed image, which, although it was introduced only at the end of the various print passes of the banknote, acts for the viewer as if it had already been carried out in an earlier work step. This leads to a significant increase in the security against counterfeiting, since the expense for Adjustments is significant, and the label 38 can not be subsequently printed with white or light color because of the partially overlapping print layer 36.

Another embodiment of the invention is in the FIGS. 4 and 5 shown, where Fig. 4 a plan view of a section of a banknote according to the invention and Fig. 5 a section along the line VV of Fig. 4 in the field of labeling shows.

In this exemplary embodiment, a colored line-shaped imprint 42, which is transparent to the laser radiation used for marking, is first applied to the paper substrate 40 of the banknote. This imprint can be printed, for example, in the nyloprint process. The imprint 42 is overprinted with an effect color layer 44 which absorbs the selected laser wavelength. Then the printed substrate is printed with an engraving ink 46 which is transparent to the laser radiation and at the same time compressed.

In the subsequent labeling step, the layer sequence from the printed side with laser radiation of a previously selected wavelength, for example, 1.064 microns, applied to the desired label 48, in the embodiment by the numerical sequence "1234" shown to bring. The absorbing effect ink layer 44 is removed locally by the action of the laser radiation, so that the underlying print 42, which is not affected by the laser radiation because of its transparency, becomes visible. The intaglio printing ink 46 is likewise transparent to the laser radiation and, owing to the good adhesion to the paper achieved by the pressing, is also retained in the lasered areas 48, so that an image impression as in FIG Fig. 4 shown results.

In other variants, the imprint 42 can also be executed, for example, in iris printing, the color transition of which is exposed in the marking areas. The imprint may also include features that are invisible to the naked eye and are only activated and / or visualized by certain lighting conditions, such as UV irradiation. Other, in particular machine-readable features can also be provided.

Similarly, the absorbent layer 22 or 44 of the embodiments of FIGS Figures 2 or 5 be executed in the iris pressure, wherein for the iris pressure expediently two colors are used, which differ in their absorption behavior at the selected laser wavelength. In the labeling step, different appearances can then be generated for the two colors. The two colors used can appear in the same color as the visible spectral range and differ only in their infrared absorption at the laser wavelength.

According to a further embodiment, for the at least partially transmissive layer 24 or 46 in steel engraving, a color section can be used which is invisible to the human eye, but leads to a different absorption at the IR laser wavelength. The partially transmissive layer can thus be removed in subregions with high IR absorption, while remaining in subregions with low IR absorption.

The FIGS. 6 and 7 show a further embodiment of the invention, in which instead of a transparent layer, an only partially permeable layer is printed, which also partially absorbs the laser radiation. Fig. 6 shows a supervision, Fig. 7 a cross section through a value document according to the invention. The in the Figures 2 and 5 indicated embossing of the layers by intaglio printing is no longer shown in the following figures for the sake of simplicity, even if intaglio printing techniques are used.

On a substrate 50, for example a banknote or another document of value, initially a laser radiation absorbing layer 52, for example a full-area silver-colored screen printing layer, is applied. On this absorbing layer 52 is printed for the laser radiation partially transparent marking layer 54 in the form of a fine line pattern. Depending on the color design of the layer 52 and the fine line pattern 54, the latter in the overlapping region is more or less clearly visible to the naked eye. The marking layer 54 consists of a color mixture of two mixture components 56 and 58, wherein one of the mixture components 56 is transparent to the radiation of the infrared laser used subsequently to the marking, while the other mixture component 58 absorbs the laser radiation. In the exemplary embodiment, the color mixture consists of a light, transparent to the laser radiation base color 56, the absorbent soot particles 58 are mixed.

In region 60, the marking layer 54 was irradiated with the marking laser with suitably selected laser parameters, whereby the absorbing mixture component 58 was removed, changed or deactivated by the action of the laser radiation. Depending on the material used, the absorbent mixture component 58 is, for example, bleached, vaporized, changed in its reflection properties or converted by a chemical reaction into a material having different optical properties, so that the optical properties of the color mixture in the region 60 are irreversibly changed by the irradiation. Possible effects include a color change, the generation of a color change, the lightening of a color, the change in the tipping color of an effect color mixture or the local change of the polarization properties or the luminescence properties of the marking layer 54. In the exemplary embodiment, the soot particles 58 are removed from the color mixture when exposed to laser radiation, so that only the light color 56 remains in the irradiated area 60, as in the plan view of FIG Fig. 6 to recognize.

In addition to altering the marking layer 54 itself, the laser radiation in the region 60 passes through the partially transmissive layer 54 and also produces a visually perceptible change in the absorbing layer 52, as described above. The identification 60, which in the exemplary embodiment is shown as a number sequence "12", is written in register in the two layers 52 and 54. Since the line pattern formed by the marking layer 54 has been printed in a single operation, the bright pattern parts and dark pattern parts inside and outside the label 60 are in perfect register with each other. In this way creates a passers situation that can not be adjusted with conventional methods.

At the in Fig. 8 shown in cross-section further embodiment of the invention, an absorbent marking layer 72 is printed on a substrate 70, which is a color mixture of two mixture components 74 and 76 of the type just described is formed. A layer 78 transparent to the laser radiation is printed over this marking layer and may be printed, for example, by intaglio printing, as above portrayed. Alternatively, even after applying a non-imprinting print layer 78, the substrate may be subjected to a calendering step to compress the printed substrate.

In the subsequent laser application of the printed substrate in the area 80, the absorbent mixture component 76 is removed from the marking layer 72, changed or deactivated, and thus introduced the marking in the coating. The transparent layer 78 remains due to the good adhesion between ink and paper in the lasered area 80.

Fig. 9 shows a banknote 90 according to a further embodiment of the invention. The absorbent layer 92 is formed in this embodiment by a colored film 94 which is vapor-deposited with a thin aluminum layer 96. A layer 98 transparent to the laser radiation is again printed on the coated film, the printed substrate being pressed during or after this printing process. For identification purposes, the banknote is subjected to infrared laser radiation in the desired regions 100, whereby the aluminum layer 96 is locally evaporated or converted into a transparent modification. Again, the transparent layer 98 is retained.

The embodiment of Figure 10 shows a configuration in which both the absorbent layer 110 and the partially permeable layer 120 is formed by a color mixture of two mixture components of the type described above, and each one for the laser radiation transparent mixture component 112 or 122 and an absorbent mixture component 114 and 124th contain. After applying the two Layers 110, 120, the printed substrate is calendered and thereby pressed.

After the laser irradiation, the absorbent mixture components 114 and 124 of the two layers in the applied marking region 116 are removed, changed or deactivated, so that this region shows a mixed color which contrasts sharply with the surrounding color.

Fig. 11 schematically shows the scan head 200 of a Vektorlaserbeschrifters, with which a substrate to be identified 202 is provided with a serial number 204 or other individualizing label. The substrate 202 may be an already finished value document, a sheet with multiple benefits of a value document, or a security paper in an endless form.

An infrared laser beam 220 is generated in the laser resonator 222 between rearview mirror and output mirror and limited by a mode diaphragm 224 to a specific beam diameter and certain spatially distributed vibration states, the so-called modes. The decoupled beam 226 passes through a beam broadening telescope 228, passes as an expanded beam 206 the input aperture 212 of the scan head 200 and is deflected by two movable mirrors 208, one of the mirrors being deflected in the x direction and the other being being deflected in the y direction generated. A plan field lens 210 focuses the laser beam 206 onto the substrate 202, where it produces a mark in the applied coating in the manner described above.

The beam broadening telescope 228 is used to ensure good focusability of the beam. The bigger the widening, the more the focusability is better by the plane field lens 210 at the end of the beam path. However, larger expansion requires the use of larger scanner mirrors 208, which have greater inertia and thus result in slower beam deflection. The beam spread is preferably adjusted so that the beam waist in which the light beams are parallel is in the plane of the plan field lens 210, resulting in good focusability of the beam.

Another adjustment option is to adjust the beam waist to the input aperture 212 of the scan head 200 to avoid losses at the edge of the beam pattern; this results in a higher beam intensity on the substrate 202.

The plane-field lenses used typically have focal lengths between 100 and 420 mm, with a focal length of about 160 mm being currently preferred. The substrate 202 moves at a certain speed v during the marking process. This velocity is detected by sensors and transmitted to a computer to control the movement of the mirrors 208 to compensate for the substrate velocity v at the marking. This marking method can therefore be used particularly advantageously for the contactless identification of documents of value, which are processed at high speeds, as usual in printing shops.

The labeling field on the substrate 202 typically has the size of a banknote. For example, at a focal length of the plan field lens 210 of 163 mm, the caption field may be formed by an ellipse having axis lengths of about 190 mm and about 140 mm.

Depending on the substrate used, radiation sources may be CO ₂ lasers, Nd: YAG lasers or other types of lasers in the wavelength range from UV to far-infrared, the lasers often also advantageously having frequency doubling or tripling. However, laser sources in the near infrared and in particular Nd: YAG lasers with a fundamental wavelength of 1064 nm are preferably used, since this wavelength range fits well with the absorption properties of the substrates and printing inks used. Depending on the application, the spot size of the laser radiation can be varied from a few micrometers to a few millimeters, for example by changing the distance between the plane field lens 210 and the substrate 202. In most cases, the spot size is on the order of 100 μm.

By changing the distance of the plane field lens 210 from the substrate 202 to be inscribed or by adjusting the beam expansion 228 in front of the scan head 200, the spot size can be selectively changed to produce fine markers with high energy density or wider markers with lower energy density. For fine markings, in particular the beam widening 228 can be adjusted such that the beam waist lies in the plane of the plane field lens 210. The beam diameter in this case may need to be reduced by the mode aperture 224 to prevent the edge of the beam image from detecting the edge of the input aperture. The total energy of the beam can thereby be reduced. Energy density and total energy in turn affect the nature and appearance of the markers.

The scan head 200 can either be attached directly to the laser or the laser light is transmitted through a light guide or via beam deflections to the scan head directed. Beam deflections are currently preferred because the power and beam quality losses are very low.

The continuous power of the laser inscribers used is typically between a few watts and a few 100 watts. Nd: YAG lasers can be operated with laser diodes for lower overall power with smaller dimensions and high beam quality, or with pump lamps for high output. In order not to reduce the speeds of an industrial manufacturing line of value documents, the markings are advantageously carried out with very fast moving galvanometers, which can guide the beam over the substrate at more than 1 m / s, preferably at more than 4 m / s. Particularly preferred and especially suitable for effects that do not require a large total energy, are speeds above 10 m / s. At these speeds, only a small proportion of energy is deposited per distance in the substrate or the coating, so that advantageous lamp-pumped Nd: YAG laser with a power of about 100 watts are used.

Examples of typical labeling parameters and settings are: A mode aperture with an opening between 1 and 5 mm, preferably 2 mm; a beam spread that is between 3 and 9 times, preferably 4.5 times; adjusting the focus of the beam-expanding telescope so as to obtain maximum power throughput at the input aperture of the scan head; a scan head designed for beam apertures between 7 and 15 mm, preferably about 10 mm; a field lens having a focal length between 100 and 420 mm, preferably about 163 mm; a working distance between lens and substrate, which is chosen so that a certain defocusing by a smaller beam spacing than he corresponds to the focal length arises; and pulse frequencies that are between 20 kHz and continuous operation.

By varying the labeling parameters, such as the laser power, exposure time, spot size, labeling speed, working mode of the laser, etc., the labeling results can be varied within a wide range. Thus, the laser linear markings, such as a label, or even filled with a line pattern area markers are generated.

To produce a linear marking, for example a lettering, the laser power is advantageously set to a value between 50 and 100 W, preferably about 80 W, and the travel speed of the laser beam to a value between 2 and 10 m / s, preferably about 7 m / s, set.

When generating a flat marking, the laser power is advantageously between 50 and 100 W, preferably about 95 W, and the travel speed of the laser beam is set to a value between 5 and 30 m / s, preferably to about 20 m / s. The line spacing of the individual lines forming the surface pattern is advantageously between 50 and 380 μm, more preferably between 180 and 250 μm.

In addition to the exposure of the substrate 202 from the front side, that is to say the printed side, as shown, lasering from the rear side of the substrate is also possible. In this case, it is advantageous if the substrate 202 has the lowest possible absorption at the laser wavelength.

The laser parameters can also be changed during the laser so that different effects result. For example, the pulse repetition frequency can be changed during pulsed laser during the process so that the partially transmissive layer is removed in certain areas.

Banknotes or value carriers are usually printed in sheet form, but it is also possible to print on webs. In general, when printing on sheets, lower register variations can be achieved, which are on the order of +/- 1.5 mm. The individual notes, also referred to below as individual benefits, are arranged in rows of benefits alongside each other. Preferably, the laser marking devices are mounted so as to be associated with a series of use as in Fig. 12 shown.

Fig. 12 shows a laser marker 230 in which a sheet 232 is provided with a plurality of lasers simultaneously with a laser mark and a laser modification area. In the example shown, the sheet 232 has six columns and six rows, so that on this sheet 36 individual benefits 234 are arranged on bank notes or other data carriers. The bow moves in the direction of the arrow. For each column, a laser tube 236 is arranged above the print sheet 232, which together with the associated scan head 238 generates the laser markings or modifications in each of the individual slots 234 arranged in this column. By this arrangement, the throughput can be greatly increased, since not a single laser beam must be moved over the entire sheet, but only a movement in the boundaries of the columns of the sheet is required. The application of the individual benefits takes place as with Fig. 11 described about the deflection of the laser radiation by means contained in the scan heads 238 mirrors.

The typical speed of a sheet-fed press is 10,000 Bg / h. Depending on the embodiment, this corresponds to web speeds of 2 m / s to 3.3 m / s. These web speeds are also achieved when printing web-like materials. Since the laser marking process is to be adapted in its speed to the typical conditions of a printing line, the markings must be able to be made on substrates which move at the said speeds. The optionally made detection of the printed image must take place at these speeds.

Fig. 13 shows a schematic view of a printing press 250, which is provided with a laser system 270 according to the invention for marking notes and the like. The laser system 270 itself is in Fig. 14 shown in more detail in cross section.

The printing press 250 has a flaker feeder 252, a printing tower 254 with a stop drum 256 for receiving the sheets, a printing cylinder 258 and inking units 260, and a tray 262. The impression cylinder 258 has portions of the circumference which receive two sheets (black in FIG Fig. 13 ) and interruptions (white in Fig. 13 ).

In the feeder 252 can be printed and only to be lasered paper sheets that go through the printing press 250 only for introducing the markings. Due to the design of the laser system 270 according to the invention, however, it is now also possible to both print and also to laser the paper sheets in the printing machine 250. The printing process carried out together with the lasering may in particular be a numbering of already printed banknote sheets, or a general printing step, for example an intaglio printing.

The inventors have now found that the most accessible location for the laser is the printing cylinder 258. In the feeder 252, the sheets are laid one on top of the other, so that the next fed sheet is guided among the following. In the tray 262, the sheets are "free fluttering", that is fixed only at the gripper edge, until they lie on the stack.

The printing cylinder 258 also has the advantage of the cylindrical elements that the circumference is dimensioned for two sheets and therefore has the least curvature. The smaller the curvature, the smaller are the distortions that must be compensated, and the less the change in the beam diameter due to the changing distance of plane field lens 210 (FIG. Fig. 11 ) and the print sheet.

A particular advantage of the construction of the laser system 270 is that the feeder 252 and the printing cylinder 258 with its paper guide and the subsequent inking units 260 remain accessible. As a result, conventional numerals, in particular also simultaneously with the laser, can be carried out with the printing press 250. An arrangement of the laser system 270 over the feeder 252 is unfavorable for this reason. The resonator 222 and the scan head 200 of each of the lasers are spatially separated according to the invention, since the laser resonators 222 can not be tilted, but must be installed horizontally for a controlled flow of cooling water.

In principle, mirrors or optical fibers can be used to guide the laser beam out of the resonator 222 into the scan head 200. However, optical fibers have the disadvantage that the beam quality deteriorates and power losses occur. In addition, the parameter range is limited because too strong pulses, as can occur in Q-switched pulse lasers, destroy the light guide. How best in Fig. 14 In the laser system 270 according to the invention, therefore, mirrors 272 which are arranged at the corners of the radiant tubes 274 are used. In cross-section of Fig. 14 only one laser is shown, but it is understood that in practice several, for example, six lasers are arranged one behind the other, as in Fig. 12 shown.

The frame of the laser system 270 consists of a reinforced frame 276, which was designed according to a finite element method analysis of the vibrations occurring. The aim is that the laser with the simultaneous printing unavoidable vibrations of the printing machine 250 perform without being rocked. The frame 276 is mounted over the housing of the inking units 260 such that the cooling water conduits of the lasers point in the direction of the cantilever, and is attached to the screw threads for cranes for transporting the printing press 250, which provide a large force absorption.

The frame 276 is formed in two parts, wherein in an outer frame, an inner frame is suspended. The outer frame can be quickly reciprocated between a plurality of detent positions and an upper position by means of externally mounted gas struts (not shown). For this purpose, for example, an awning crank and a winch can be used. The detent positions are the different possible focal lengths the plan field lenses 210 and thus associated with the various working distances.

The inner frame is finely adjustable, for example, by means of cranks in height and in angle, in order to allow an exact adjustment of the height of the plane field lens 210 and the direction of the radiation 206. The altitude can be displayed by scales and is therefore exactly reproducible. Due to the locking positions, this adjustment is not lost, for example, when working on the inking units 260, the laser should be moved back up and back.

The resonators 222 are disposed on plates 278 which can be displaced together with the radiant tubes 274 to align the labeling units on the rows of benefits. Above the pressure cylinder 258, a shielding chamber 280 is arranged, which shields the laser radiation and serves for the extraction of the resulting gases and dusts via pipes, not shown in the figure. The shielding chamber 280 is mounted so that its position is not changed at the different locking positions for the standard working distances; Only at the position for working on the inking unit 260 is it driven upwards. The shielding chamber 280 closes off to the impression cylinder 258 with laser light impermeable brushes and to the scan heads 200 by means of bellows 282.

The laser is controlled by a sensor for detecting the sheet or pressure and by measuring the speed. The sheet edge sensor is a high-precision and fast reflection light scanner.

The speed of the printing cylinder 258 is picked up by periodically magnetized belts, which were placed under the supports of the printing cylinder, from a magnetic switch. The printing cylinder has yes parts of the circumference on which no bow comes to rest. The scan achieves a resolution of 25 μm. The assumption of a constant speed is not possible because the various simultaneous operations of the printing press 250 are typically driven by a central motor and therefore the sheet travel is subject to periodic variations.

The signal from the reflection light scanner is fed to a "trigger box", which controls the laser. It can be programmed in such a way that, for laser applications, the starting distance, measured via the magnetic tapes, and the spacing of the sequential marks can each be input independently of each other via a computer program.

A blocking for further signals of the reflection light scanner can be determined either as a blocking distance or by a determination of the sheet position by the magnetic tapes. In this case, only after one end of the magnetic tape (and thus the end of the sheet) a start signal is allowed and blocked from a start signal until it reaches an end of the magnetic tape.

Claims (16)

1. A method for manufacturing a data carrier (10, 30, 90) having a visually perceptible marking (14, 38, 48, 60, 80, 100, 116) in the form of patterns, letters, numbers or images, in which

   a) a predefined laser radiation spectrum is chosen,

   b) a substrate (20, 40, 50, 70) of the data carrier (10, 30, 90) is provided,

   c) a laser-radiation-absorbing layer (22, 44, 52, 72, 92, 110) is applied to the substrate (20, 40, 50, 70) of the data carrier (10, 30, 90),

   d) over the absorbing layer (22, 44, 52, 72, 92,110) is imprinted a layer (24, 46, 54, 78, 98, 120) that is at least partially transmissive to the laser radiation,

   e) the substrate (20, 40, 50, 70) is pressed during or after the application of the at least partially transmissive layer (24, 46, 54, 78, 98, 120), and

   f) the applied coating is impinged on with laser radiation of the chosen laser radiation spectrum to produce the visually perceptible markings (14, 38, 48, 60, 80,100,116) at least in the absorbing layer (22, 44, 52, 72, 92,110).
2. The method according to claim 1, characterized in that the at least partially transmissive layer (24, 46, 54, 78, 98, 120) in step d) is applied by means of intaglio printing and, in doing so, the substrate is pressed.
3. The method according to claim 1, characterized in that, after the application of the absorbing (22, 44, 52, 72, 92, 110) and the at least partially transmissive layer (24, 46, 54, 78, 98, 120), the substrate is blind embossed.
4. The method according to claim 1, characterized in that, after the application of the absorbing (22, 44, 52, 72, 92,110) and the at least partially transmissive layer (24, 46, 54, 78, 98, 120), the substrate is calendered.
5. The method according to at least one of claims 1 to 4, characterized in that the at least partially transmissive layer (24, 46, 54, 78, 98, 120) in step d) is imprinted in the form of fine patterns, especially in the form of guilloches, microtext, graphic elements or the like.
6. The method according to at least one of claims 1 to 5, characterized in that the absorbing layer (22, 44, 52, 72, 92,110) in step c) is imprinted, especially by means of screen printing, or that in step c), a coated or uncoated foil (94) is applied as the absorbing layer.
7. The method according to at least one of claims 1 to 6, characterized in that the absorbing layer (22, 44, 52, 72, 92,110) in step c) is applied in sub-regions with different printing methods or printing parameters, such that the sub-regions are affected differently upon the laser impingement in step f).
8. The method according to at least one of claims 1 to 7, characterized in that the laser parameters in step f) are chosen such that the at least partially transmissive layer (24, 46, 54, 78, 98, 120) is completely maintained upon laser impingement, or that the laser parameters are changed during the impingement in step f) to partially maintain and partially remove the partially transmissive layer (24, 46, 54, 78, 98, 120).
9. The method according to at least one of claims 1 to 8, characterized in that the laser parameters in the impingement in step f) are chosen such that embossings in the coating are maintained, or that the laser parameters are changed during the impingement in step f) to partially maintain and partially remove the embossings in the coating.
10. A data carrier (10, 30, 90), especially a value document or security paper, having a substrate (20, 40, 50, 70) and, applied on the substrate (20, 40, 50, 70), a coating into which, through the action of laser radiation, markings (14, 38, 48, 60, 80,100,116) in the form of patterns, letters, numbers or images are introduced, wherein the coating includes a laser-radiation-absorbing layer (22, 44, 52, 72, 92,110) and a printing layer (24, 46, 54, 78, 98, 120) that is disposed over the absorbing layer (22, 44, 52, 72, 92, 110) and that is at least partially transmissive to the laser radiation, characterized in that the printed substrate (20, 40, 50, 70) is pressed, obtainable by pressing during or after the imprinting of the at least partially transmissive layer (24, 46, 54, 78, 98, 120).
11. The data carrier (10, 30, 90) according to claim 10, characterized in that the at least partially transmissive layer (24, 46, 54, 78, 98, 120) is formed by an intaglio printing layer.
12. The data carrier (10, 30, 90) according to at least one of claims 10 to 11, characterized in that the data carrier exhibits a blind embossing in the region of the marking (14, 38, 48, 60, 80, 100, 116).
13. The data carrier (10, 30, 90) according to at least one of claims 10 to 12, characterized in that the at least partially transmissive layer (24, 46, 54, 78, 98,120) is imprinted in the form of fine patterns, especially in the form of guilloches, microtext, graphic elements or the like.
14. The data carrier (10, 30, 90) according to at least one of claims 10 to 13, characterized in that the absorbing layer (22, 44, 52, 72,92,110) is formed by a printing layer, especially a screen printing layer, or that the absorbing layer (22, 44, 52, 72, 92,110) is formed by a coated or uncoated foil.
15. A use of a data carrier (10, 30, 90) according to at least one of claims 1 to 14 for securing goods of any kind against counterfeiting.
16. A printing machine (250) having a laser system (270) for carrying out the method according to at least one of claims 1 to 9, characterized in that the laser system (270) is disposed above an impression cylinder (258) of the printing machine (250) to impinge on the pressed data carrier (10, 30, 90) to be marked, on the impression cylinder (258), with laser radiation.

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