EP1525102B1 - Security document - Google Patents

Description

The invention relates to a security paper with a tactile detectable mark and a value document with a security paper and to a method for producing the value document or the security paper.

Banknotes, checks, tickets, tickets and other documents of value, in particular made of paper, are equipped with security features for the purpose of forgery-proofing, by means of which the authenticity of the value documents can be checked.

In this connection, it has been proposed to apply laser radiation markings on a document in order to achieve an irreversible and visually easily detectable change of the document. For example, in the DE 28 36 529 C2 proposed to burn out the serial number from a printing ink layer by means of a suitably controlled laser beam. In the EP 0 918 649 B1 It is proposed to repeat the identification number by locally reducing the document thickness by means of laser etching elsewhere in the document. In the two aforementioned cases, in each case material is thus removed by means of laser radiation.

In contrast, other approaches provide to merely blacken the substrate material by means of laser radiation. In order to achieve particularly legible and edge-sharp markings, it is also known to mix the paper absorbents and carbon formers, such as micro-milled plastics ( DE 197 32 860 A1 ).

Another way is the DE 198 22 605 A1 , It is proposed to first treat the paper substrate surface with laser energy in order to structurally alter the surface and then to provide it with an opaque coating, for example by printing, painting and / or metallizing. The prior modification of the surface results in the subsequently applied coating to a noticeable change in the color density, the color location, the gloss and / or the reflection, whereby a visible security feature arises.

In the US 4,740,269 A a security paper is described on which a security feature is generated by means of a laser. The laser beam creates a relief-like structure through structural changes to paper fibers or by removing a layer of paint. In particular, material is vaporized in the security paper, wherein in the lasered area in addition a protective layer can be applied.

The aforementioned security features are each visually recognizable security features. However, there is basically a need for further, new security features, in particular also for security features that are perceptible with another sense organ, for example tactile security features that can be detected by the sense of touch.

The object of the present invention is therefore to propose a security document for a document of value with a tactile detectable security feature and a method for producing such a security feature on a document of value.

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

According to the invention, a value document made of security paper is marked by means of a laser, so that a tactile marking in the form of a raised relief structure is produced. The relief structure is formed by fibers of the security paper and has a height of 30 .mu.m to 100 .mu.m.

It has been found that with appropriate coordination of the composition of the security paper and the labeling parameters, such as type of laser used, laser power, operating mode of the laser, and wavelength in the security paper, a relief-like structure can be achieved, which is tactile detectable.

According to a particular embodiment of the invention, the laser marking also leads to a color change or a color change of the security paper in the marked area. This allows a simple check by the human eye or by an image processing device due to the clear contrast to the environment. The type and color shade of the color change depends on the composition of the security paper used. Security papers are preferably used for the value documents according to the invention, in which the laser inscription produces a light gray to black marking.

This color change may be enhanced by suitable additives which may be included in the security paper. The type of additives used depends on the type of laser used or the laser wavelength used. Conceivable are laser radiation absorbing additives such as carbon black, thermochromic substances, laser iriodines from Merck or even titanium dioxide.

If this blackening of the security paper is undesirable, the security paper can be moistened again before the labeling process. As a result, the gray to black appearance disappears. The tactility of the mark is not affected. So you get a visually unrecognizable or barely perceptible mark, which is very noticeable.

As security paper papers are preferably used which contain at least proportions of fibers of annual plants, such as cotton, linters or flax. In particular, security papers which contain only cotton fibers or a mixture of cotton fibers and synthetic fibers are suitable. A plastic fiber content of about 12% by weight, based on the total weight of the security paper, is preferred.

Particularly good results are achieved with cotton vellum paper with a mean fiber length of 1 mm. These papers contain as filler TiO ₂ , which absorbs at a wavelength of 1064 nm and is used in particular for adjusting the opacity and the suppression of luminescence emissions of the paper. As sizing, poly-vinyl alcohol (PVA) is preferably used for these cotton vellum papers.

The security paper can also be designed in multiple layers. For example, the security paper can consist of two paper layers, between which any other layer, such as a color layer, metal layer or foamable layer, is arranged. The foamable layer promotes the formation of the tactile marking by the laser beam. Such foamable layers may contain, for example, black powder or blowing agents which develop gas under the action of heat, or hollow chamber balls which contain a gas which expands under the influence of heat. However, these intumescent additives can also be added to the paper directly or to one of the layers of a multilayer security paper. Alternatively, it is also possible to offset the surface sizing of the security paper with these additives.

For the laser marking of such security papers, pulsed Nd: YAG lasers with a wavelength of 1064 nm are preferably used. Depending on the desired relief structure or desired degree of blackening and / or line width of the information to be displayed, other laser types and / or wavelengths or labeling parameters may be expedient. For example, frequency-doubled or frequency-tripled Nd: YAG lasers can also be used in pulsed or in continuous wave mode. CO ₂ or excimer lasers can also be used.

For cotton vellum papers, Nd: YAG lasers are preferably used at the fundamental wavelength of 1064 nm with an average power of 65 W and a modulation frequency of about 10 kHz. At these settings, the speed at which the laser is moved across the paper is between 330 and 1350 mm / s, with the diameter of the laser beam impinging on the paper being about 120 μm. However, the speed can be further increased to values up to 2700 mm / s. In this case, however, the modulation frequency of the laser must be increased to approx. 12 kHz. The labeling speed is very much related to the necessary surface energy for producing a tactile marking. For untreated cotton vellum papers, this surface energy is at least 0.31 J / mm ² . However, this value can be changed by appropriate additions in the paper, in particular be lowered, so that higher labeling speeds are possible.

The height of the tactile relief relative to the surface of the document of value in turn depends on the labeling speed. At medium to high speeds, relief heights of 30 to 80 μm can be achieved. At slow speeds also 100 μm relief height can be used will be realized. Here, therefore, a compromise must be chosen from the desired relief height and economical inscription speed.

The line width and thus the resolution of the tactile marking is limited to the top by the diameter of the laser beam, that is, the resolution corresponds to the maximum diameter of the laser beam. In many applications, however, line widths of approximately 200 to 600 μm are sufficient.

The marking parameters can also be set so that the relief structure has different relief heights and / or degrees of blackening within the marking. The generatable relief height can be increased or decreased stepwise or continuously. In this way, direction-dependent, tactile markings can be generated. That depending on in which direction one strokes over the marking, the relief is more or less palpable.

The relief height of the marking can also be increased by multiple irradiation of the same spot with laser radiation. Also, laser beam and security document to be inscribed security paper need not necessarily be arranged perpendicular to each other. The laser beam can enclose any angle with the paper.

For the generation of information according to the invention also different laser energies can be used, so that within the information different relief heights and / or blackening arise. If, for example, a two-dimensional code is generated in this way, a three-dimensional code can be generated by the different blackening. That is, the degree of blackening is considered a further coding level used, which can be evaluated eg with appropriate detectors.

By means of laser marking, alphanumeric characters can be represented, for example serial numbers of the value documents or any codes, such as one-dimensional or two-dimensional bar codes or blind codes, any symbols or images. Also, any alphanumeric characters, such as date, time, batch designation, or logos, such as the signature of a minister or president of the central bank, are possible.

Of course, any geometric patterns can be generated, such as a knobbed structure. The tactile nubs can be very small due to the relatively small laser focus, i. small diameter, and compared to this large elevation can be generated over the surface of the document. This type of label with high resolution structure combined with strong grandeur, i. high tactility, can not be readjusted by printing.

According to a further embodiment, the environment of an information to be displayed may be designed to be tactile while the information itself can not be tactually sensed. That is, the information is executed in the form of a negative representation.

The marking can be embodied as information which can be recognized visually without aids or as a microfilm, which can be clearly recognized only by means of a magnifying glass. The tactile marking can be arranged without substantial restriction at any point on the surface of the value document or even at several points of the value document.

Likewise, the markings produced according to the invention with a laser can supplement markings produced in other ways and thus form a new security element. For example, a colored line print can be combined with a line relief produced according to the invention so that the colored lines come to lie on the flanks of the relief. When the viewing angle is varied, this results in different visual impressions due to shadowing effects.

If several markings are applied to a value document, these markings may be identical or different in content. Alternatively, the tags may also be in any context with each other or with information generated by other users on the document, thereby contributing to a further increase in anti-counterfeiting security. For example, a check digit calculated for the serial number of the value document can be lasered.

The value document according to the invention is any document whose essential component is a security paper, such as a banknote, a check, a visa, a label, a passport or another document to be secured from security paper. Within the scope of the invention, the document of value may also consist of a paper / film composite, wherein the area of the security paper with the tactile laser marking should preferably be freely accessible in order to ensure the tactile testability. This can take place in that the value document or the security paper has a film only on the side facing away from the marking, or that the region of the marking in the form of a window in the film is recessed. It may also make sense to laser marking over the boundary between paper and slide film. Depending on the labeling parameters used, the film is merely blackened or additionally broken up, so that a further tactile relief is created.

It has also been shown that the tactile marking can be overprinted without sacrificing tactility. If it is e.g. provided with a metallic overpressure, so create special light / dark effects, depending on the reflection of the metal-colored layer. If the ink appears bright at a certain viewing angle due to the directed reflection, then the diffusely scattering, tactile marking is recognizable as dark information against this bright background and vice versa.

Alternatively, the tactile marking may also be overprinted with a printing ink having the same hue as the laser-generated tactile marking. For example, if an Nd: YAG laser operating in the infrared spectral region is used to generate the tactile marking and the tactile marker shows a gray appearance, then this marker can be overprinted with a gray printing ink to mask the visual visibility.

The value document according to the invention can have further security features, such as a security thread, an optically variable security element, a security imprint or machine-readable security features, such as, for example, luminescent or magnetic substances. If the value document has a security thread, the laser marking according to the invention can also be provided in the area of the security thread. If the security thread as a so-called "window security thread" in the document of value so to speak, that is, the security threads occurs in places directly to the surface of the value document, the Laser marking are provided in the intermediate areas in which the security thread is embedded in the value document. Alternatively, as already mentioned, the marking may also extend over the boundary area foil / paper, so that the security thread likewise carries a laser marking. It is also possible, an exclusive marking of the security thread in the window area. The value documents according to the invention can also be used to secure products of any kind.

According to a specific embodiment, the tactile marking according to the invention can also be combined with other tactile security elements, such as intaglio printing. Here, the different Taktilitäten be exploited. The relief produced by the intaglio printing forms a hard or sharp transition to the environment, while the marking according to the invention has a soft transition and a soft, velvety, tactile surface.

For example, the tactilely tactile intaglio mark can form the frame for a colored, non-tactile field, which preferably has the same color as the tactile tactile edge and is also produced in intaglio. If this color absorbs laser radiation, it is ablated when exposed to the laser and at the same time the tactile laser marking can occur. The laser marking can also be produced without ablation of the color layer. This colored area can additionally be lined with a primer layer which contains luminescent substances and / or positively influences the release properties of the paint to be ablated and / or positively influences the durability of the ink which is not to be removed.

According to a further embodiment, the printing ink arranged in the region of the laser marking may also have magnetic or conductive properties or be formed by an organic semiconductor layer which illuminates (OLED). The subsequent laser marking creates disruptions in the mechanically measurable signal of the individual layers, which can serve as a further authenticity feature. These disturbances can be e.g. individualizing information, such as the serial number. In this way, the visually visible and tactile laser marking can also be checked by machine.

According to a further variant, the security paper or document of value can also be provided with a coating which contains soot and hollow chamber balls. In the case of the laser inscription according to the invention, the laser radiation is absorbed by the proportion of soot and a visually visible blackening results. At the same time, the hollow-chamber spheres expand or are destroyed with the evolution of gas, so that a well-felted relief is created. In the blackened area, there are no longer any hollow spheres. In the area of the edges of the laser marking, on the other hand, there are still inflated, undamaged hollow spheres, which diffuse the light diffusely and create a contrast to the environment. When tilting the document or security paper additionally results in a contrast reversal due to the different reflective properties of the flanks and the surrounding areas.

According to a particular embodiment, the value document has an additional coating in the region of the tactile marking according to the invention. The laser marking can be completely or only partially in the region of the coating. This can be any print image, such as alphanumeric characters, logos, patterns and guilloches, a full-surface paint or lacquer layer or even a multi-layer security element, such as an observable in reflection, diffractive optical effective structure act. The coating can therefore be printed on, evaporated; sprayed or transferred in the transfer process. The laser inscription is preferably introduced into optically variable printing layers, such as liquid-crystalline pigments or printing layers containing interference-layer pigments, or metallic layers, for example of aluminum, silver or gold.

If the coating is transparent to the laser radiation used, the marking parameter in the underlying security paper will produce the tactile marking which simultaneously conveys the coating without destroying it. If the coating is translucent and the laser marking causes a color change in the security paper, this is visible in addition to the tactile relief of erfindungsgmäßen marker. If the coating is a colored printed image or a color layer, its color impression can be determined by the marking underneath, i. color change of the security paper. In this way, in a colored area next to a tactile marking also a visually recognizable mark can be generated, which differs in hue from the environment.

If, on the other hand, absorbent coatings are used which absorb the laser radiation, a partial or complete removal of this coating takes place before or simultaneously with the actual marking of the security paper. The marking is also visually recognizable in this case, since in this area the coating has been removed.

According to a particular embodiment of the invention, the coating consists of a multi-layer security element applied to the security paper or document of value, for example in the form of a label or transfer element. In the simplest case, the security element has the following sequence of layers from the viewer: a plastic layer, preferably a lacquer layer, a metal layer, such as a thin aluminum layer, and an adhesive layer for securing the security element to the security paper or document of value. The lacquer layer may additionally have an embossing which produces visually observable diffraction-optical effects, such as a hologram or any diffraction grating image. When marking with a laser, preferably a Nd: YAG laser, the metal layer is removed in regions. At the same time, the marked security paper arched up the film layer structure of the security element so that the tactile marking is created. The lacquer layer of the security element is by this process, depending on the choice of labeling parameters, not, hardly or completely removed. If the marking parameters are selected appropriately, the security paper is simultaneously blackened. This blackening is clearly visible through the transparent area of the security element which has been freed from the metal layer. The marking parameters can also be adjusted so that the area in which the metal layer is removed is greater than the portion provided with a tactile marking.

Since the tactile detectable laser-marked area is surrounded by an extremely smooth area in this embodiment, the tactility of the security feature is further enhanced.

The tactile detectability of the security feature can also be improved by calendering the substrate prior to laser marking.

This also creates the security feature in a particularly smooth environment.

The creation of a tactile mark by means of a laser on the other hand works better on rough surfaces, i. In order to achieve a certain relief height, a lower laser energy is necessary for rough surfaces.

According to a further embodiment, the security paper or document of value can also be acted on by the surface opposite the film element with the laser radiation. This results in the tactile marking on the laser-facing surface. At the same time, the metal layer of the film element is ablated in the applied region, so that the marking is also visible on the side of the film element. It therefore creates a kind of transparency register.

According to a specific embodiment, the fiber-containing substrate of the value document is marked by laser radiation at least in a partial area of its surface in such a way that the fibers in the laser-marked partial area project out of the surface of the substrate so as to form a tactile detectable security feature.

The fibers of the security paper usually run in the surface area substantially parallel to the surface of the security paper and are held by the sizing in this position. Due to the laser radiation, the fiber composite is broken and individual fiber ends are released from the dressing, so that the fibers protrude beyond the substrate surface due to their residual stress. Preferably, these fibers form a braid projecting beyond the substrate surface which creates the tactile marking.

In this context, cotton vellum paper and other cotton security papers which have long fibers with high tear strength compared to other papers have proven particularly suitable fibrous substrate materials. These types of paper are particularly suitable for security printing anyway. Tests with cotton safety paper using an Nd: YAG laser (wavelength 1064 nm) have led to particularly good results, as already explained in detail.

Also in this embodiment of the invention, a coating may be provided on the surface of the substrate, through which the laser marking takes place. According to a first variant, the coating is evaporated by means of laser radiation and the fiber structure of the underlying fibrous substrate is broken, so that the fibers protrude from the substrate surface. The coating may, for example, be a film, in particular a hologram film. The tactile detectable, laser-marked portion is in this case surrounded by a very smooth area, whereby the tactile detectability of the security feature is enhanced.

According to a second variant, the coating consists of a layer which does not absorb the laser radiation, in particular a two-dimensional imprint or a pattern print, such as a guilloche pattern. Such printed color layers are regularly so thin that they break with the breaking up of the underlying fiber structure, so that the fibers of the substrate in turn tangibly protrude from the substrate surface.

The non-absorbing layer can also be a surface-smoothing, in particular transparent, thin lacquer layer, which is likewise broken by the fibers which detach from the fiber structure. This variant is also characterized by an increased detectability of the tactile security feature within a smooth environment.

As a non-absorbing layer, any thin coating is suitable, which is broken when breaking the fiber composite by the uplifting fibers, whether they are printed, vapor-deposited or sprayed.

It is particularly advantageous if the non-absorbing layer contains additives, for example luminescent substances, which are only visible under special conditions or which are recognizable only in the non-visible wavelength range, in particular in the UV range. As a result, in addition to the tactile detectable security feature, another security feature is integrated particularly advantageously into the value document. For by setting up the fibers of the substrate and breaking up the non-absorbing layer, a particular contrast is achieved in comparison with the region of the non-absorbing layer surrounding the laser marking, which can be detected visually or with suitable checking devices.

According to a particular embodiment, the laser marking also leads to a color change or a color change of the marked portion, whereby a significant increase in contrast for checking by the human eye or by an image processing device is achieved.

This color change is, as already explained, preferably reinforced by suitable additives which may be contained in the fibrous substrate. Depending on the nature of the additives chosen, the color change is thermally caused by the energy introduced by the laser radiation or by other wavelength-dependent color change mechanisms. Also suitable as additives in this example are laser iriodines from Merck. The thermally generated color change can be additionally reinforced by suitable absorption substances. If the raised and tactile markings are also visually distinguishable from their environment due to a change in color of the marked areas, this has the advantage that adjustments can be made more difficult by simply embossing, since the markings in this case would also have to be printed in register to have the corresponding color contrast.

The tactile mark can also be created by an interaction of different mechanisms. Thus, the laser radiation alone can cause a swelling of the fiber substrate or a breakage of the fiber structure. As described, breaking the fiber structure results in a relief structure formed by fibers protruding from the substrate surface. Depending on the substrate material used or the laser parameter used, the tactile relief can also consist of a combination of the mentioned effects. In this case, the substrate material is both inflated and at least partially broken, so that individual fibers protrude from the substrate surface and form a network interspersed with voids.

The laser marking step takes place at any stage in the production of the value document. So it may be useful, the security paper after production in roll form with a corresponding Mark to provide. This is the case, in particular, when the security paper is provided in continuous form with a film coating, such as a diffraction-optically effective, for example, strip-shaped security element, and this security element is to be provided with a marking according to the invention as described above.

However, the step of laser marking is preferably carried out as one of the last working steps in the production of the value document. If the value documents are printed, for example, in the form of sheet-shaped multiple uses, the laser marking can still take place on the sheet or already on the cut, finished value document. The latter is particularly useful if a tangible individual information, such as a serial number, should be generated by means of laser marking. If necessary, the lasered information can be checked for correctness in a final step.

A particular safety advantage of the present invention is the fact that the effect described can not be adjusted by simple means. The use of lasers requires high investments and in-depth technical know-how, which goes far beyond the level of knowledge required for the use of conventional printing presses or digital printing devices.

Another advantage of the invention is that the laser marking can be performed without contact in a speed typical for printing companies. In particular, each document can be individually marked by, for example, integrating the serial number or another individualizing feature as a tactile security feature in the value document. It is particularly advantageous if the coating or at least one of the layers of the coating or the security element additives, such as luminescent substances are added, which are visible only under special conditions or which are visible only in the non-visible wavelength range, especially in the UV or IR range. As a result, in addition to the tactile detectable security feature, another security feature is integrated into the value document.

It is also possible to provide a laser-absorbing coating which is vaporized and a non-absorbing layer on top of each other on the fibrous substrate, the layer to be vaporized being expediently present as the uppermost layer.

A further advantage of the invention can be seen in the fact that for the first time tangible markings can be provided in the edge area of a value document, in particular a banknote, with the aid of laser inscription. For the time being, it is undesirable to extend a tactile printed image produced in intaglio printing to the marginal area of the individual documents, since the printing process takes place on the sheet and in this case smears the cutting tools with paint. By contrast, the tactile marking according to the invention does not hinder the cutting process in any way, so that the marking can be extended into the cutting edge. This has the advantage that the tactile marking is perceived as an authenticity feature immediately, as bank notes are primarily touched at the edge.

The advantages of the invention will be explained with reference to the following examples and additional figures. The described individual features and embodiments described below can also be combined with each other. The examples represent preferred embodiments, to which, however, the invention in no way should be limited. The proportions shown in the figures do not correspond to the conditions present in reality and serve primarily to improve the clarity.

Fig. 1

ein erfindungsgemäßes Wertdokument,

Fig. 2

das erfindungsgmäße Wertdokument im Querschnitt entlang der Linie A - A,

Fig. 3

Variante der Faserstruktur eines erfindungsgemäßen Wertdokuments,

Fig. 4

weitere Ausführungsform des erfindungsgemäßen Wertdokuments im Querschnitt entlang der Linie A - A,

Fig. 5

Schnitt durch das erfindungsgemäße Wertdokument entlang der Linie B - B,

Fig. 6

ein erfindungsgemäßes Wertdokument mit einer im Randbereich angeordneten erfindungsgemäßen Markierung,

Fig. 7

Variante des erfindungsgemäßen Wertdokuments im Querschnitt,

Fig. 8

weitere Variante des erfindungsgemäßen Wertdokuments im Querschnitt,

Fig. 9

weitere Variante des erfindungsgemäßen Wertdokuments im Querschnitt,

Fig. 10

weitere Variante des erfindungsgemaßen Wertdokuments im Querschnitt,

Fig. 11

schematische Darstellung einer Laserscanner-Schreibvorrichtung,

Fig. 12

schematische Darstellung einer Laserbeschriftungsvorrichtung für die Beschriftung eines Wertpapierbogens.

Show it:

Fig. 1

a value document according to the invention,

Fig. 2

the value document according to the invention in cross section along the line A - A,

Fig. 3

Variant of the fiber structure of a value document according to the invention,

Fig. 4

further embodiment of the value document according to the invention in cross section along the line A - A,

Fig. 5

Section through the value document according to the invention along the line B - B,

Fig. 6

an inventive value document with a marking according to the invention arranged in the edge region,

Fig. 7

Variant of the value document according to the invention in cross-section,

Fig. 8

further variant of the value document according to the invention in cross-section,

Fig. 9

further variant of the value document according to the invention in cross-section,

Fig. 10

further variant of the inventive value document in cross section,

Fig. 11

schematic representation of a laser scanner writing device,

Fig. 12

schematic representation of a laser marking device for labeling a security sheet.

Fig.1 shows a value document 1 according to the invention in the form of a banknote. The value document 1 according to the invention has a tactile marking 2 in the form of a relief structure which has been produced by the action of a laser beam. The example shown additionally has a security element 3 in the form of a patch, which may be, for example, a transfer element or a label with structures having a diffraction-optical effect. In the area of the security element 3 there is likewise a laser marking 4 according to the invention, which can be tactually felt. The two laser markings 2, 4 are identical in content in the example shown. Furthermore, the security document on a further information 9, which is applied with any other method such as by intaglio printing or inkjet.

However, the two laser markings 2, 4 can also be designed completely independently of each other or stand in a certain relationship with each other, which forms an additional authenticity feature. Thus it can be checked whether the security element 3 actually to the value document 1 belongs. Likewise, one or both laser markings may be in any contextual relationship with other information on the value document, such as information 9.

Of course, the security element 3 can also have any other shape. Thus, it may be useful in certain embodiments to execute the security element 3 in the form of a strip over the entire width or length of the value document 1. It is also possible to provide only one of the laser markings 2, 4 on the value document 1. Instead of the security element 3, another type of coating, such as e.g. a paint or foil coating, or any printed image can be selected.

The value document 1 can, in addition to the tactile laser marking according to the invention, also have other security features, such as, for example, a security thread, luminescent, electrically conductive or magnetic security features.

Also, the document of value 1 need not necessarily be a banknote, but may represent any other document from a paper substrate, such as a check, a security tag, a visa, a passport page. It is essential that one of the freely accessible components of the value document consists of a fibrous paper substrate. It is preferably pure cotton fiber paper or a mixture of cotton and plastic fibers.

Fig. 2 shows a section through the document of value 1 along the line A - A. In the area of the laser marking 2, the security has a tactile increase 5, which is caused by the action of the laser beam. How far the elevation 5 protrudes beyond the remaining substrate surface 6, depends very much on the laser energy used and the relative speed between the document of value and the laser beam during the inscription process.

The actual fiber structure in the marked area also depends very much on the labeling parameters and the paper substrate used. In a paper made of cotton fibers, which is provided with a glue layer, this glue layer, together with the calendering of the paper, ensures a uniform and, to a first approximation, closed surface.

Fig. 3 FIG. 2 shows the surface area of such a security paper 20 according to the invention made of cotton fibers in the region of the laser marking 2. The entire section of the security paper 20 shown is impregnated by the glue layer, which however is not shown for reasons of clarity. In the region 61, the security paper 20 on the production-related uniform surface. In the field of laser marking, the glued surface is broken and the fiber composite is loosened, ie cavities 52 are likely to be formed between the fibers 51 due to gas evolution. With correspondingly high laser energy, a relatively coarse-meshed braiding of cotton fibers 51 forms over the surface 61 of the security paper 2, which are still covered by the glue layer.

Since the tactile increase 5 may look completely different for a different paper composition, the tactile marking according to the invention is shown only schematically as a raised area 5.

In Fig. 4 is also a section through the document of value 1 along the line A - A shown. By the action of the laser beam, however, a change in color, in particular a blackening 7, of the valuable document material was produced here in addition to the elevation 5. Whether and how deep the color change or blackening 7 is present in the value-added document material 1 likewise depends very greatly on the labeling parameters and the composition of the security paper used for the value document 1.

Fig. 5 shows a section through the document of value 1 along the line B - B. In this case, a coating in the form of a security element 3 is arranged in the region of the laser marking 4, wherein the security element 3 consists of a transfer element. The transfer element is attached to the value document 1 by means of an adhesive layer 31. Between the adhesive layer 31 and a plastic layer, in particular lacquer layer 33, there is a metal layer 32. This metal layer 32 is missing in the area of the laser marking 4. In the laser marking process, the metal layer 32 is vaporized and / or decomposed and is no longer visible. The color change 7 caused by the laser inscription is therefore visible through the lacquer layer 33 and the adhesive layer 31. The labeling parameters can be adjusted so that the area in which the metal layer 32 is removed is greater than the portion provided with a tactile marking. In this way, the visually visible, caused by the laser, color change or blackening is surrounded by a transparent area.

In the example shown, the plastic layer 33 and the adhesive layer 31 are hardly or not damaged by the laser. Whichever Inscription parameters can be used, single or both layers can also be partially or completely removed.

Instead of the transfer element, the fiber-containing substrate may also be provided with a transparent or pigment-containing color layer. It is essential in this context that the ink layer does not absorb the laser radiation used for laser marking. The color layer may be applied to the substrate in any manner, for example printed on it. It is particularly advantageous if the color layer produces a smooth impression of the substrate surface. In this sense, "paint layer" is also a dirt-repellent, possibly transparent, coating or protective coating to understand.

Since the color layer does not absorb the laser radiation used, the absorption of the laser energy takes place only in the substrate layer. The elevation 5 is thus generated in the substrate, so that a tactile marking is produced within the color layer.

Preferably, the non-absorbing ink layer contains dyes that are visible only under certain conditions, such as luminescent dyes, or that have properties that are invisible to the human eye, such as infrared or UV-emitting materials.

The color layer does not have to be full-surface. It can also be a color pattern, in particular one of the guilloche patterns frequently used in security printing. The only condition is that the color layer of the pattern is largely transparent to the laser radiation used.

Fig. 6 shows a further embodiment of the inventive value document 1 in supervision. In this case, the tactile marking 2 extends into the edge region of the value document 1. Since banknotes are usually touched on the edge during manual processing or in conventional payment transactions, this arrangement of the tactile security element in the edge region has the advantage that it is very simple and easy can be checked quickly. Other tactile authenticity features, such as a tactile tactile intaglio, can not or only poorly be arranged in the edge region of the document of value 1, since the documents of value are printed in sheets with several uses and then cut into the individual pieces. In an arrangement of the intaglio printing element in the edge region, however, there is a risk that smear when cutting the sheet in single-use the cutting tools with paint.

The Fig. 7 to 10 show different embodiments of the tactile laser marking 2 in a single-layer security paper 100.

In Fig. 7 For example, different laser parameters, in particular laser energies, are used to generate a sawtooth-like, tactile relief 25. This embodiment has the advantage that it feels different depending on the strike direction from left to right or right to left. This feature can be used as an additional security feature. Due to the different laser energies used, a different blackening effect is created, which is visually recognizable. The individual saw teeth thus have different gray levels.

In Fig. 8 a security feature is described, which consists of a combination of a tactile tactile intaglio printing element and one according to the invention produced tangible laser marking exists. In the example shown, the tactile intaglio mark 26 forms an edge region enclosing the tactile laser marking 27. In the intaglio printing method, the security paper 100 is pressed into the intaglio printing plate, so that the paper is deformed in this area. At the same time the paper takes on the color 28 in the embossed area. The tactile tactile effect of the intaglio printing mark 26 is accordingly produced by the embossing and the simultaneous high application of ink 28 in the embossed area. This type of marking forms steep flanks and, as a hard, abruptly sloping element, is tactile to distinguish very well from the soft, almost velvety laser marking 27.

In Fig. 9 a security paper is shown, which was printed in a first step with colored line patterns 30, 31. Subsequently, the border area between the printed lines 30, 31 is inscribed according to the invention by means of a laser, so that a tangible relief is created: Due to the bulging of the security paper in area 5, the lines 30, 31 are shifted onto the flanks of the raised areas 5. This combination of printed lines 30, 31 and raised areas 5 forms an optically variable security element that provides different visual impressions depending on the viewing direction. If, for example, the lines 30 are lines of a first color and the lines 31 are lines of a second color, only the colored lines 31 of the second color can be seen in the oblique view from the left. The security element therefore appears in this second color. The lines 30 are not recognizable due to the shading effects. In oblique viewing from the right, however, the lines 31 are shaded, so that ideally only the colored lines 30 can be seen. The security element thus appears in the first color. The printed and the lasered lines do not necessarily form an exact grid; it is sufficient if a proportion of the printed lines form the effect.

Figure 10 shows a further embodiment of the security element 100 according to the invention. In this example, a security element 3 is arranged on a surface of the security paper 100, as already described in connection with FIG Fig. 5 has been described. This security element consists of an adhesive layer 31, a diffraction structure 34 and a reflection layer 32 and a protective layer 33. This security paper 100 is provided on the opposite surface with a laser marking 2 according to the invention. In this case, the laser energy and the other laser parameters are adjusted so that a raised mark 5 is formed and at the same time the originally continuous metallization 32 of the security element 3 is destroyed in the area acted upon by the laser. That is, the security element 3 is transparent in the area acted upon by the laser radiation, so that the blackening generated simultaneously with the raised marking 5 is visible through this transparent area. Unlike the in Fig. 5 shown example, the increase 5 according to the invention, however, is on the opposite side of the security element 3 and is practically not felt on the surface of the security element 3.

The exemplary embodiments can also be combined with one another by first arranging the color layer on the surface of the substrate and, above this, a film-shaped material. The laser initially evaporates the film-shaped material and exposes the color layer underneath the film. By further action of the laser, as already explained, the tactile marking 5 is produced in the substrate.

If the film material is embodied as an opaque film, for example as a metallized plastic film, the laser marking 5 also produces a clearly visible contrast due to the underneath and exposed ink layer.

In the event that a color layer is arranged in the region of the laser marking, the fibers protruding from the substrate surface provide a clear contrast to the surroundings, which can be detected with suitable checking devices. This effect is therefore well suited for automatic machine testing.

Fig. 11 schematically shows a laser scanner, with which a substrate 10 is provided with a laser marking 11. The substrate 10 can be an already finished value document, a sheet with several benefits of a value document or a security paper in an endless form.

A laser beam 12 is deflected by means of two mirrors 13 which are driven by galvanometer 14, one mirror 13 being responsible for the x- and the other mirror 13 for the y-orientation. In a plane field lens 15, the laser beam 12 is focused on the surface of the substrate 10 and generates the mark 11. The substrate 10 can move at speed v during the marking process. This speed v is detected by sensors and transmitted to a computer in order to control via the computer, the galvanometer 14 so that the speed v is compensated. This marking method can therefore be used particularly advantageously for non-contact marking of value documents, which are processed at high speeds, as usual in printing shops.

The substrate 10 can also be marked in another way, for example by means of a matrix of punctiform emerging laser beams or by means of beams of larger cross-section, which are partially hidden by a template. Such templates can be executed automatically changeable. If entrainment of the radiation in accordance with the speed v is not possible or undesirable, marking of moving substrates is also possible by selecting a short exposure time. Also the beam guidance by polygon mirror is possible.

As radiation sources, depending on the CO belasertem substrate ₂ laser, Nd: YAG laser in question or other laser types, for example, also those which, like Nd: can work with frequency doubling or tripling YAG laser.

By varying the labeling parameters, such as laser power, exposure time, working mode of the laser, the marking results can be varied. Thus, the elevations generated by the laser can be varied in height accordingly. Preferably, the tactile marking has a height of 30 to 100 microns. It is also necessary to adapt the composition of the paper to the laser radiation or laser power used.

The markings are made, for example, with an Nd: YAG laser whose fundamental wavelength is 1064 nm and which has an average power of 26 W and a modulation frequency of 8 kHz. The diameter of the laser beam on the substrate (spot size) is about 100 microns and the travel speeds of the laser beam over the substrate 250 to 1000 mm / s. The typical height of a marking produced according to the invention is between 30 and 80 μm. In individual cases, ie in particular At low speeds, significantly higher values were achieved, for example, a height of over 100 microns at 250 mm / s. The width of the markings can be varied between 0.2 and 0.6 mm.

For a calendered cotton vellum paper with a density of 90 g / m ² , for example, at a labeling speed of 330 mm / s, tactile markings with an average relief height of 70 μm and a line width of approximately 500 μm are obtained. At a marking speed of 675 mm / s, on the other hand, the achievable relief height is only 40 μm for the same line width.

For a paper made from a blend of cotton and plastic fibers having a plastic fiber content of 12.5% by weight and a basis weight of 90 g / m ² (so-called Synthek paper), the dimensions of the marking produced at 250 mm / s are 65 μm medium height and approx. 0.5 mm average width. When increasing the travel speed to 1000 mm / s, the dimensions were 35 μm average height and 0.3 mm average width.

Fig. 12 shows an embodiment of the device according to the invention, in which a sheet is provided with a plurality of lasers simultaneously with a marking according to the invention. In the case shown, the sheet on six columns and six rows, so that 36 individual benefits are arranged on documents of value on this sheet. For each column, a laser tube is arranged above the printing sheet, which in each case provides the individual components arranged in this column with the marking according to the invention. By this arrangement, the throughput can be greatly increased, since not a single laser beam moves over the entire sheet must be, but only a movement parallel to the columns of the sheet is required. The labeling of the individual benefits takes place via deflection of the laser radiation by means of mirrors, which are not shown in the example shown. In addition, the lasers may be provided with a scanning head 43.

Claims (31)

1. A security paper for value documents, such as bank notes, ID cards, which has at least one palpable marking in the form of a raised relief structure, which is formed by fibers of the security paper and produced by means of a laser, and has a relief height of 30 µm to 100 µm.
2. The security paper according to claim 1, characterized in that the security paper has a visually recognizable color change in the region of the palpable marking.
3. The security paper according to claim 1 or 2, characterized in that the security paper is blackened in the region of the palpable marking.
4. The security paper according to at least one of claims 1 to 3, characterized in that the color change is produced with the laser.
5. The security paper according to at least one of claims 1 to 4, characterized in that the palpable marking has a relief height of 30 µm to 80 µm.
6. The security paper according to at least one of claims 1 to 5, characterized in that the security paper contains at least in certain regions additives which enhance the color change and/ or relief formation.
7. The security paper according to at least one of claims 1 to 6, characterized in that the security paper contains at least proportions of fibers of annual plants, such as cotton, linters, flax.
8. The security paper according to at least one of claims 1 to 7, characterized in that the security paper has a mixture of cotton and plastic fibers.
9. The security paper according to at least one of claims 1 to 8, characterized in that the relief structure of the marking has different relief heights and/ or degrees of blackening.
10. The security paper according to at least one of claims 1 to 9, characterized in that the palpable marking is present in the form of alphanumeric characters, bar codes, patterns or microwriting.
11. A value document, such as for example bank note, which comprises a security paper according to any of claims 1 to 10.
12. The value document according to claim 11, characterized in that several of the palpable markings are present on the value document.
13. The value document according to claim 11 or 12, characterized in that several of the palpable markings are present on the value document, which represent identical information or information connected in content.
14. The value document according to at least one of claims 11 to 13, characterized in that the palpable marking represents information which is identical to another information on the value document or is connected in content with the other information on the value document.
15. The value document or security paper according to at least one of claims 1 to 14, characterized in that the value document or security paper has a coating and that the palpable marking is arranged at least partly in the region of this coating.
16. The value document or security paper according to claim 15, characterized in that the coating is a multilayer security element.
17. The value document or security paper according to claim 16, characterized in that the security element has at least one plastic layer and one metal layer, whereby at least the metal layer, at least in the region of the palpable marking, is removed by the action of the laser.
18. The value document or security paper according to claim 17, characterized in that the plastic layer has a diffraction structure.
19. The value document or security paper according to claim 17 or 18, characterized in that the region in which the metal layer is removed is greater than the region provided with a palpable marking.
20. The value document or security paper according to at least one of claims 15 to 19, characterized in that the coating is a print.
21. The value document or security paper according to claim 20, characterized in that the print is arranged on the palpable marking in such a way that there results an optically variable element.
22. The value document or security paper according to at least one of claims 1 to 19, characterized in that the value document or security paper has a transition between paper and a foil and that the palpable marking extends over the paper/foil border region.
23. The value document or security paper according to at least one of claims 1 to 21, characterized in that the value document or security paper is of multilayer design.
24. A method for manufacturing a palpable marking in a value document, such as for example a bank note, which has a security paper, whereby the security paper is exposed to laser radiation, and the inscription parameters of the laser and the composition of the security paper are adjusted to each other in such a way, that there results the palpable marking in the form of a raised relief structure, which is formed by fibers of the security paper and has a height of 30 µm to 100 µm.
25. The method according to claim 24, characterized in that the inscription parameters are selected such that there results, in addition to the palpable marking, a visually recognizable color change of the security paper.
26. The method according to claim 24 or 25, characterized in that the security paper is blackened in the region of the palpable marking by the laser radiation.
27. The method according to at least one of claims 24 to 26, characterized in that the inscription parameters of the laser are set such, that there result different relief heights and/ or degrees of blackening in the security paper.
28. The method according to at least one of claims 24 to 27, characterized in that a coating is applied onto the value document or security paper before the inscription with the laser, and the palpable marking is produced at least partly in the region of this coating.
29. The method according to at least one of claims 24 to 28, characterized in that as a coating a multilayer security element is applied by transfer method.
30. The method according to at least one of claims 24 to 29, characterized in that a Nd:YAG laser is employed.
31. The method according to at least one of claims 24 to 30, characterized in that the inscription is effected with the laser at a speed in the range of 250 to 2700 mm/s.

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