EP3243669A2 - Security element and method for its production - Google Patents

Abstract

The invention relates to a method for producing a security feature (12) for a security element, a security paper or a data carrier, wherein a carrier (38) is provided which has a front side (14) and a rear side (16), the carrier (38). is provided with a coating (42) which is modifiable by laser radiation (34) in terms of their color, and by the action of laser beam in the beam cross-section (34) of the carrier (38) is locally changed in thickness, wherein at the same time the coating (42 ) is modified by the laser radiation (34) with respect to the color, wherein the carrier (38) on its rear side (16) with the coating (42) is provided and the laser radiation (34) from the front side (14) on the carrier (38 ) is irradiated, wherein as a local change in thickness, a hole (24) in the carrier (38) is generated and due to the intensity distribution over the beam cross section, a zone (52) one surrounding the edge (46) of the hole (24) on the back (16) of the carrier (38) is modified in color.

Description

The invention relates to a method for producing a security feature for a security element, a security paper or a data carrier, wherein a carrier is provided which has a front side and a rear side, the carrier is provided with a coating that is modifiable by laser radiation in terms of their color, and the carrier is locally changed in its thickness by the action of laser beam intensity-distributed in the beam cross-section, wherein at the same time the coating is modified by the laser radiation with respect to the color. The invention further relates to a security feature for a security element, a security paper or a data carrier, comprising: a carrier having a front side and a rear side, wherein the carrier is provided with a coating which is modifiable by laser radiation in terms of their color, by means of Laser radiation of the carrier is locally changed in thickness, and wherein the coating is modified by laser radiation in terms of color, and a security element, a security paper and a value document or a data carrier with such a security feature.

Identity cards, such as credit cards or identity cards, are often laser engraved with an individual label. The production of continuous openings in value documents, eg banknote papers, by laser cutting has also been known for some time. For example, in the document DE 4334848 C1 describes a security with a closed by a transparent cover film window-like opening, which can be generated by a laser cutting process.

The WO 2009/003587 A1 describes a manufacturing method and a corresponding security feature of the type mentioned, which is produced by a laser cutting method by laser radiation is radiated from an upper side onto the carrier. The support of the security feature is previously coated on top with a marker which changes color by the action of laser beams. For the production of the hole or the holes, a cutting laser beam is used whose intensity is distributed non-uniformly over the beam cross-section, for example Gaussian. Such radiation is referred to herein as laser radiation which is intensity-distributed across the beam cross-section, the radiation intensity decreasing towards the edge of the laser beam. As a result of this drop in intensity, an edge occurs at the top at which the support is no longer cut, but a modification of the marking substance with regard to its color effect takes place. In this way, the edge region of the hole produced by means of laser radiation appears colored at the top. This effect is from the WO 2011/154112 A1 and WO 2010/07232 A1 known.

A colored border of holes is also from the WO 2009/003588 A1 However, several laser beams of different intensities are required in order to achieve a particularly large and thus well-recognizable color effect.

Laser radiation-sensitive marking substances are known, for example, from the following publications: EP 1657072 B1 . EP 2332012 B1 . US 7270919 . US 7485403 . US 7998900 . US 8021820 . US8048608 . US8048605 . US 8083973 . US 8101544 . US 8101545 . US 8105506 . US 8173253 . US 8178277 . US 8278243 . US 8278244 and US 842028 ,

From the EP 1641627 B1 A method for applying markings on both sides of a security paper is known, wherein the processing takes place from one side. In order to provide the page opposite side of the paper with a security mark, laser radiation is radiated through the paper, wherein the laser radiation ablated on the opposite side applied photosensitive layer or changed in color.

The WO 98/36913 is also concerned with the creation of security markings on both sides of a security paper, using a laser beam which simultaneously performs an ablation on the front and back of the security paper so as to produce identical markings on both sides.

The DE 102010053052 A2 discloses a data carrier containing a mark produced by the action of laser radiation, which produces a different visual appearance when viewed than in a plan view.

The invention is therefore based on the object to further improve a security element, security paper and data carriers of the type mentioned in terms of imitation security and to simplify the manufacturability.

This object is achieved by a method for producing a security feature for a security element, a security paper or a data carrier, wherein a carrier is provided which has a front side and a rear side, the carrier is provided with a coating which can be modified by laser radiation with respect to their color is, and by the action of laser beam in the beam cross-section intensity-distributed the carrier is locally changed in its thickness, wherein at the same time the coating is modified by the laser radiation in terms of color, wherein the carrier is provided on its back with the coating and the laser radiation is irradiated from the front of the carrier, wherein as a local change in thickness Hole is generated in the carrier and due to the intensity distribution over the beam cross section, a zone surrounding an edge of the hole at the back of the carrier, is modified in terms of color.

The object is further achieved by a method for producing a security feature for a security element, a security paper or a data carrier, wherein a carrier is provided, which has a front side and a rear side, the carrier is provided with a coating which by laser radiation in terms of their color is modifiable locally by changing the beam cross-section intensity-distributed laser radiation, the carrier is modified in thickness, wherein at the same time the coating is modified by the laser radiation in terms of color, wherein the carrier is provided on its back with the coating and the laser radiation from the front the carrier is irradiated, wherein the change in thickness is a depression on the front side of the carrier and a zone located on the rear side of the carrier below the depression is modified in color.

The object is also achieved by a security feature for a security element, a security paper or a data carrier, comprising: a carrier having a front side and a rear side, wherein the carrier is provided with a coating that is modifiable by laser radiation in terms of their color, wherein by means of laser radiation, the carrier is locally changed in thickness, and wherein the coating by Laser radiation is modified in terms of color, wherein the carrier is provided on its rear side with the coating and the local change in thickness is a generated by the laser radiation from the front in the carrier hole, wherein a zone which is an edge of the hole at the back of the carrier surrounds, is modified by the laser radiation in terms of color.

The object is also achieved by a security feature for a security element, a security paper or a data carrier, comprising: a carrier having a front side and a rear side, wherein the carrier is provided with a coating that is modifiable by laser radiation in terms of their color, wherein the carrier is locally changed in thickness by means of laser radiation, and wherein the coating is modified by laser radiation in color, the carrier is provided on its back with the coating and the local change in thickness by means of the laser radiation from the front of the carrier generated depression is, wherein a zone which lies at the back of the carrier under the recess, is modified by the laser radiation in terms of color.

The invention causes by irradiation of the laser radiation from the front to the carrier a change in thickness of the paper. This change in thickness is local. It can also be carried out as a reduction to the thickness zero, ie as a hole. At the back, which is opposite to the front, from which the laser radiation is irradiated, the laser radiation causes a color modification. This happens because the intensity of the laser radiation is no longer sufficient here for removing carrier material, ie, the hole is not further enlarged or the depression is even deeper, but is still capable of modifying the coating. In this way arises on the opposite side one Color marking in the exact register for thickness modification, which is incorporated from the front.

The terms "front" and "back" are used in this specification solely with reference to the irradiation of the laser radiation. The front side is the side on which the laser radiation is irradiated, the back side is the opposite side of the carrier. The carrier is flat. The terms front and back have nothing to do with a later use of the wearer. The term choice is not intended to imply that one of the pages must or may not have a particular meaning for use.

The invention provides two variants: First, the paper is cut. Then the local change in thickness is a hole. On the other hand, a depression or incision is made, ie the paper is thinned or scratched from the front. In both variants, the local thickness change is accurate to the color modification on the back. So there is a hole or a depression / scratching, which is accurate to the color effect on the back.

The fact that a hole is produced by means of laser radiation can be recognized by the fact that during laser cutting, an edge adjusts to the direction of incidence of the laser beam, which is not exactly parallel to the direction of incidence, since the ablation effect of the laser beam decreases with increasing depth into the carrier. A security feature indicates that a hole was created by a laser beam and was not punched.

The registration accuracy can also be used on the front, if this is also provided with a coating that is modifiable by the laser radiation in terms of their color. It then occur, for example, from the WO 2010/072329 A1 Known effects that the edge to the thickness reduction on the entrance side has a color marker. In the first variant, in which the change in thickness is a hole, this hole then has a colored edge on the front and on the back. The color effects can be different if you use coatings on the front and back that differ in their color effect. Also, because of the mentioned fact that the edges of a laser cut are always at a certain angle to the direction of incidence of the laser radiation, the color marks on the front and back face each other in a characteristic register, which is ultimately defined by the parameters of the laser beam (intensity distribution, total intensity and angle of incidence to the Surface of the front and back) and the thickness of the carrier is determined. The same applies to the second variant, in which the thickness change is a depression. Here, in a preferred development, it can be ensured that the color marking on the rear side is bordered by the color marking on the front side relative to the perpendicular to the surface of the front and rear sides. In a transmitted light view you can see the color mark on the front as a circumferential edge or ring around the color marking on the back.

It is provided in a preferred development of the invention to combine laser-markable coatings with different reaction enthalpies. For example, a substance that requires less energy input (and therefore lower temperatures) for color modification can be used in the backside coating. Is the energy input on the Top of the carrier very high, a substance B, if it has a lower reaction enthalpy than a substance A, can be destroyed by the comparatively increased energy input, while substance A is maintained. The laser energy is attenuated as it passes through the substrate, causing a color modification on the reverse side and not destroying substance B. It is thus possible to generate two colors on the backside by varying the intensity of the laser radiation.

In the case of the second variant, in which the local change in thickness is an incision or depression on the upper side of the carrier, this, although a coating is applied to the upper side, has a colored border.

The security feature can be further improved in terms of its security against counterfeiting by using a pasted into a paper or on it, in particular a window spanning, glued security thread in the case of banknotes when a hole is inserted in the security thread, which extends as a recess in the carrier, including Under this recess on the back of the carrier the color modification takes place. The color effect then interacts with the hole that is introduced into the security thread, so that the hole appears colored in a transparent view. This is particularly beneficial for metallic security threads, which have a reflective effect in supervision. The security feature then shows the hole in supervision as a missing reflex, so for example as a dark impression, and in see-through view, the hole is colored.

A similar effect is obtained when the security thread is applied to the front but not perforated with the laser radiation but only provided with a recess. If at the same time a color-modifiable coating is applied between the security thread and the carrier on the front, it is modified under the security thread. The color then seems due to the recess, which locally reduces the thickness of the metallic security thread, in transmitted light also colored. In both developments using a security thread, a perfect register accuracy is achieved by the production process.

The security thread may also be used in addition to a change in thickness produced without it.

Furthermore, the two variations of the thickness change can also be combined. This is by adjusting the parameters of the laser radiation, for example, the irradiation time, the z. B. can be adjusted via the cutting speed, or the laser radiation intensity easily possible. Then a hole or a depression is created in the carrier depending on the corresponding parameters.

It should be noted that the recesses and / or holes can provide motifs or alphanumeric characters, as one skilled in the art mentioned above, for example in the WO 2010/072329 A1 and WO 2011/154112 A1 or even the WO 2009/003588 A1 is known. The variants described there are likewise usable within the scope of the invention described here.

Insofar as the terms "above" and "below" are used in this description, this position statement refers to the direction of incidence of the laser radiation.

The term "color" is not limited to a colorful impression, but can also include white and black and the change between transparent and opaque.

The marking substance need not be further structured or specially applied for the registration between color and hole / depression. It is even possible to provide the marking substance over the entire area in a much larger area than the surface treated with laser radiation occupies.

It is exploited that the laser beam energy in an outer region of the beam cross section is sufficient to modify the marking substance in the zone around the edge of the hole or under the depression. This automatically ensures perfect registration of the aperture and the laser-modified zone.

As a marker material come into question with advantage whose visible color is changed by the action of the laser radiation. For example, thermoreactive colored pigments such as ultramarine blue can be used for this purpose. Advantageously, it is also possible to use marking substances whose infrared-absorbing properties or their magnetic, electrical or luminescent properties are changed by the action of the laser radiation. Security features with such laser radiation-modified hole edges can be used in particular for mechanical authenticity testing. It is also possible to use a combination of different marking substances, for example in order to enable both a visual and a machine authenticity check of the security feature. When using multiple markers they can both side by side and in different Laying layers on top of each other. Alternatively, in one embodiment of the invention, the modification of the carrier / marker may be erosion or destruction. The marker is preferably a metallic coating in this case.

According to an advantageous variant of the invention, laser radiation-modifiable effect pigments are used as the laser-radiation-modifiable marker. Such effect pigments are available to the person skilled in the art with different properties, in particular with respect to their body color, the color change under laser radiation, the threshold energy and the required laser radiation wavelength. Also, effect pigments which change not only their visible color under laser radiation but their infrared-absorbing, magnetic, electrical or luminescent properties are known to the person skilled in the art. The modification of the effect pigments can be made with laser radiation in the ultraviolet, visible or infrared spectral range, for example, a CO ₂ laser of a wavelength of 10.6 microns.

In a further likewise advantageous variant of the invention, a pigment-free laser-radiation-modifiable marker is used. Pigment-free marking substances can also be applied to the support, for example as a stich or printing ink. With pigment-free marking materials, a coating of high transparency can be produced, into which a permanent and high-contrast marking can be introduced by laser action at high speed. Pigment-free marking substances can be modified by laser radiation in the ultraviolet, visible or infrared spectral range, for example with the 10.6 μm radiation of a CO ₂ laser. Concrete, non-limiting examples of pigment-free laser-modifiable markers are in the documents WO 02/101462 A1 . US 4343885 and EP 0290750 B1 specified, the disclosure of which is included in the present description in this regard.

The invention also encompasses a security element for security papers, documents of value and the like with a security feature produced according to the methods described. The security feature has a carrier, which is locally changed by the action of laser radiation in terms of its thickness and at the same time has a modified by the laser radiation in terms of color zone. The color-modified zone lies on the underside, which is opposite to the front side from which the laser radiation is introduced. If the local thickness change is a hole, the zone in which the color is modified is at the edge of the hole. If the thickness modification is a depression, the color zone is below the depression. Such a security element may for example be in the form of a security thread, a label, a transfer element or a covering film for a window area or a hole in a value document, such as a banknote.

In addition, the invention also includes a security paper for the production of value documents or the like with a security feature produced according to the described method. The invention further includes a data carrier with a security feature produced by the method described, in particular a value document such as a banknote, identity card or the like, wherein the data carrier has a carrier.

Further embodiments and advantages of the invention will be explained below with reference to the figures, in the representation thereof to a scale and proportioned reproduction has been omitted in order to increase the clarity.

Fig. 1

eine schematische Darstellung einer Banknote mit einem Sicherheitsmerkmal,

Fig. 2

eine Detailaufsicht auf eine mögliche Realisierung des Sicherheitsmerkmals der Fig. 1 von der Vorder- und Rückseite,

Fig. 3(a)-(b)

eine räumliche Energieverteilung eines Laserstrahls zur Erläuterung der Herstellung des Sicherheitsmerkmals,

Fig. 3c

eine Schnittdarstellung eines Teils des Sicherheitsmerkmals der Fig. 1 und 2 in einer ersten Ausführungsform, in welcher Löcher mit farbigem Rand erzeugt werden,

Fig. 4

eine Schnittdarstellung ähnlich der Fig. 3c, jedoch für eine zweite Ausführungsform, in welcher Vertiefungen auf einer Vorderseite des Sicherheitselementes und dazu in genauer Passerung farbige Bereiche auf der Rückseite des Sicherheitselementes erzeugt werden,

Fig. 5

eine Darstellung ähnlich der Fig. 2 für eine abgewandelte Variante des Sicherheitselementes und

Fig. 6-8

Darstellungen ähnlich den Fig. 3 und 4, wobei ein ein Fenster überspannender Sicherheitsfaden oder Patch vorgesehen ist, der ebenfalls mit Laserstrahlung strukturiert ist und einen in Passerung dazu liegenden Farbbereich hat.

Show it:

Fig. 1

a schematic representation of a banknote with a security feature,

Fig. 2

a detailed supervision of a possible realization of the security feature of Fig. 1 from the front and back,

Fig. 3 (a) - (b)

a spatial energy distribution of a laser beam to explain the production of the security feature,

Fig. 3c

a sectional view of part of the security feature of Fig. 1 and 2 in a first embodiment in which colored edge holes are produced,

Fig. 4

a sectional view similar to the Fig. 3c however, for a second embodiment, in which recesses are produced on a front side of the security element and to a precise registration colored areas on the back of the security element,

Fig. 5

a representation similar to the Fig. 2 for a modified variant of the security element and

Fig. 6-8

Representations similar to the Fig. 3 and 4 wherein a security thread or patch spanning a window is provided, which is also structured with laser radiation and has a passerung lying to color range.

The invention will be explained using the example of a banknote. The Fig. 1 shows a schematic representation of the banknote 10, a in Fig. 2 has security feature 12 shown in more detail.

The security feature 12 is exemplarily characterized by a motif in the form of an outline 18. Fig. 2 shows the security feature 12 in the left-hand illustration of a front side 14, in the right-hand illustration of an opposite rear side 16 forth. Correspondingly, the outline 18 in the right-hand representation is mirrored in relation to the left-hand representation. The outline 18 was generated by passing a laser beam over the front side 14. Previously, the rear side 16 has been provided with a laser-markable coating which, when exposed to laser radiation above a certain energy, exhibits a color effect, for example changes its color. In this regard, reference is made to the above general part of the description. The intensity of the laser radiation was varied when the outline 18 was traversed, so that the outline 18 consists of different sections. In some sections, the intensity of the laser radiation has been adjusted so that recesses 20 are incorporated into the carrier material of the security feature 12 from the front side 14. In other sections, the laser radiation is switched off or reduced so that no processing of the carrier material takes place. This results in gaps 22, which in the left illustration of Fig. 2 symbolized by a narrow black line. The depressions 20 are symbolized by an unfilled line. In other sections, however, the laser radiation intensity was adjusted so that a Hole 24 is produced through the carrier. The holes 24 are symbolized by thicker, unfilled lines.

The effect of the laser radiation on the back is in Fig. 2 to recognize. in the sections in which there is a gap 22 on the front side 14, there is also a gap 22 in the outline 18 at the rear side 16. At the locations where recesses 20 lie, there is a color marking 28, since the intensity of the Laser radiation at the exit on the back 16 was still sufficient to modify the laser-modifiable coating in terms of their color. At the locations of the holes 24, there is also a hole on the rear side 16, which, however, now has a colored edge 30 due to the coating.

This design of the outline 18 results in a total of the front side 14, a motif 26, the mirror image and in a different color design as a motif 26 'is also recognizable on the back 16.

Of course, embodiments can also work only with holes or depressions and without gaps. Also, the motifs need not be limited to outlines 18. Large holes / depressions are equally possible, for. B. to produce areal motifs.

The principle of simultaneous creation of holes or depressions and the color scheme is in Fig. 3a illustrated. Fig. 3a shows by way of example a substantially Gaussian spatial intensity distribution of a laser beam 34. The fluence therefore decreases from the center to the edge.

In an inner region, a first working region A1, the laser beam intensity exceeds that required for cutting or ablation of the carrier Minimum energy E1. With E2 is in Fig. 3a denotes a reaction energy of the marker, when said exceeding the color change occurs. As can be seen directly from the figure, in an outer region of the laser beam profile, a second working region A2, the fluence between the reaction energy E2 required for the color change and the minimum energy E1 required for cutting is present, so that only a color change is induced in this region 34 but the carrier is not cut.

The carrier is therefore discolored in the laser cutting by the laser beam in a zone at the back edge of each hole 24 in perfect registration with the hole 24. The width of the colored edge 30 corresponds to the width of the second working region A2 and depends on the intensity distribution over the beam cross-section, the reaction energy of the effect pigments used and the material properties of the carrier, for. B. of the banknote paper.

Outside the first working area A1 and the second working area A2, the laser beam intensity is below the reaction energy of the coating, so that the carrier is not changed in color there.

As a coating which changes its visible color by the action of the laser radiation, for example, thermoreactive color pigments, such as ultramarine blue, come into question.

It will be appreciated that two or more different threshold energy coating substances or a combination of visually and mechanically detectable substances may also be used to produce multiple passivated edge effects.

Instead of the coating substance described by way of example, it is also possible to use a pigment-free laser-radiation-modifiable marking substance. Also, such markers can be printed on the carrier as a coating, for example as Stichdruck- or printing ink. Non-pigmented, laser-radiation-modifiable coatings can have a very high transparency in the unlabeled state. By the action of laser radiation, for example a CO ₂ laser at 10.6 microns can be a high speed permanent and high-contrast markings, for example, produce a black marking in the coating.

It is also possible that the heat generated during laser cutting causes the modification. In this way, the modified edge area of the opening can optionally be even larger than the beam extent.

Fig. 3b shows a beam profile of a laser beam 34, which has a lower maximum energy. The laser beam is thus able to insert a recess in the material of the carrier, but does not produce a hole. The depression is introduced as soon as the energy of the laser beam is above a threshold value E3. The maximum width of the recess is given by a width given by the first and the second working range A1 + A2. In a core region, the intensity of the laser beam as it exits the rear of the carrier also exceeds the energy E2 required to change the color of the laser-modifiable coating applied to the back surface 16. In the first working area A1, this results in the color marking 28 on the back under the depression.

The explanations based on the Fig. 3a and 3b assume a substantially Gaussian spatial distribution of the energy of the laser beam 34. As explained below, it is not absolutely necessary that the intensity profile is Gaussian. Furthermore, the invention is not limited to the generation of circular holes. Rather, with the laser radiation 34 also, like the Fig. 2 shows a line to be cut.

The Fig. 3a and 3b use a constant cutting speed. At a constant cutting speed and high maximum power, the energy input of the laser radiation into the material of the carrier exceeds the energy required to produce a hole in the working area A1 or the energy required to produce a depression in the area A1 + A2. The energy E1 needed to create a hole, or the energy E3 needed to create a pit but not a hole, is of course affected by the cutting speed. In this way, the hole size, for example the cutting width, or the recess depth along the path along which the laser beam is guided, can be varied as desired at a constant cutting speed by the virtually instantaneous possible variation of the laser power.

The same applies if the laser radiation is kept constant by a change in the cutting speed. At a high cutting speed, the laser radiation acts only relatively briefly on the material of the carrier, so that the energy input is comparatively low. Accordingly, the energy E1 or E3 required for generating a hole or generating a depression is exceeded only in a small range. At a lower cutting speed, however, the laser radiation acts longer on the material of the carrier, so that a higher energy input results in the carrier. Accordingly, there is a larger hole or a deeper and / or further depression, since the area in which the energy E2 or E3 is exceeded, is correspondingly larger. Accordingly, the structuring of the outline, which in Fig. 2 also be produced in one operation, that the cutting speed is varied in the transition from the sections 24 with a hole 22 with a gap and 20 with a depression accordingly. To create the hole 24, the cutting speed must be the lowest, to create a gap highest. Inverse applies to the energy at constant cutting speed. To create the depressions 20, it is in between.

For the sake of simplicity, the effects of changing the laser parameters energy and cutting speed were explained separately. It is understood, however, that the two parameters can also be changed together and simultaneously to have a greater range of variation and / or a finer setting available. An optimization with regard to the fastest possible processing of the carrier is of course possible.

It is also possible, as an option, for the marking substance to be removed or destroyed directly next to the cutting edge, and for it to be modified only from a certain small distance from the cutting edge.

It is essential for the production of the colored edge 30 that the laser beam 34 has an intensity distribution which is not constant, ie has no top hat profile. Any intensity profile in which the intensity of the laser beam 44 decreases toward the edge of the beam cross-section with respect to the maximum value can be used for generating the colored edge 30, the type of intensity profile naturally being based on the width of the beam Edge 30 relative to the maximum hole diameter of each hole 24 effects. On the other hand, when creating a recess on the front side with discoloration on the rear side lying in register-wise position, an intensity distribution is also possible which has a top-hat profile. Such a profile is therefore suitable for executions that work exclusively with depressions and do not produce holes with colored borders on the back.

Fig. 3c shows a schematic sectional view through the security feature 12 in the region of a hole 24. In the sectional view can be seen that the carrier 38 is provided on its front side 14 with a laser-modifiable coating 40. The back 16 carries a laser-modifiable coating 42. The coating 40 is optional. From the front side 14, the laser radiation 34, for which the beam profile is applied by way of example, is irradiated from an incident direction 36, which in the selected example is perpendicular to the front side 14 and the rear side 16. The laser beam 34 creates the hole 24 having an upper edge 44 and a lower edge 46. Due to the usual for laser radiation Materialabtrages results for the hole edge 48, which is oblique to the direction of incidence 36. In other words, the width of the hole at the bottom 46 is less than the width at the top 44. The width at the bottom is B1 in Fig. 3c entered.

The laser radiation modifies at the upper edge 44 and at the lower edge 50 the coatings 40, 42 applied there, so that a colored edge 50 on the rear side 16 and a colored edge 52 on the front side 14 for the hole 24 result. A color edge width C1 at the bottom colored edge 50 and a color edge width C2 at the top colored edge 52 are shown by the Fig. 3a explained effect of the intensity distribution of the laser beam 34th certainly. Also by the intensity distribution of the laser beam and thus its cutting action and equally by the thickness of the carrier 38, an offset D1 between the lower and upper colored edge 50, 52 is determined.

This offset D1 can, as in Fig. 3c be registered, be positive. But it can also be negative, ie the lower colored edge 50 and the upper colored edge 52 overlap when viewed along the direction of incidence 36. This offers a person of design options with regard to the logo 26 in plan view or review.

Further, it is possible to choose the coatings 40 and 42 differently, i. H. the colored edge 50 may have a different color than the colored edge 52. This opens up further design possibilities, in particular in combination with a negative offset D1. In the case of a negative offset D1, the hole is shown in three-color outline. The color of the lower edge 50 is shown in an inner area. In an outer area, the color of the upper colored border 52. In the area of the negative offset D1, the mixture is shown the two colors. As a result, the hole 24 is trimmed in three colors.

Fig. 4 shows a further embodiment in which the laser beam 34 does not produce a hole 24 but a depression 54. The laser beam exiting at the rear side 16 there still has an energy above the minimum energy E 2, at least in sections below the depression 54, which is required to produce the color effect in the coating 42. It thus turns on the bottom 16 a color zone 56, which lies in a precise position to the recess 54. The recess 54 may be used as a scratch on the front side 14 to modify the optical impression of the carrier 38 from the front side 14. In Fig. 4 is how in Fig. 3c Also, the optional coating 40 on the front side 14 is provided. It thus sets at the top of a colored edge 52 of the recess 54, which is also in precise register position to the ink zone 56. The ink zone 56 has an extent D2, which is predetermined by the intensity distribution of the laser beam 34 in combination with the thickness of the carrier 38 and optionally the cutting speed (as explained above). The upper colored edge 56 has a width C2, again with an offset D1, which may also be positive or negative. The above based Fig. 3c Explained here applies equally, now in place of the lower colored edge 50, the color zone 56 occurs.

Fig. 4 shows that there are portions of the depression 54 under which no ink zone 56 lies. These are those portions where the energy of the laser beam as it exited the backside 16 was insufficient to modify the coating 42 in color. This makes it possible to thin out the carrier 38 in areas, ie to reduce its thickness, without producing a color zone 56 underneath.

It should be noted that generally, d. H. for all embodiments, the structuring of the color markings in the coatings 42 and, if present 40, does not depend on a structured application of the coatings, but is generated by the laser radiation. Of course, a combination with a structured application of the coatings is possible to achieve an additional structuring of motifs.

The embodiment of the Fig. 4 allows a scratching of the front side 14 of the carrier 38, which is in register with the ink zone 56 on the back 16 and, if provided, also to a colored edge 52 on the front side 14 of the carrier 38th

The coatings on the front and back can use various laser-sensitive marking substances. It is possible to provide a first fabric at the front and back showing a first color change. It is also possible to use a first fabric with a first color change at the front and a second fabric with a second color at the back. In addition, this can be combined with laser energies / cutting speeds, which ensure that the fabric is removed so that the original color of the fabric no longer exists. This can be considered as a third color change, which is ultimately an ablation of the substance.

It is also possible to combine laser-sensitive substances with different reaction enthalpies within each coating. Thus, in one embodiment, for the coating 42 on the backside 16, a fabric may be used which requires less energy to change the color. This substance is referred to below as the second substance. In one embodiment, it is combined with a first substance which has a higher reaction enthalpy. These fabrics are included in combination in the front 14 and rear 16 coatings. If the energy input on the front side 14 is very high, the second substance, which has a lower reaction enthalpy than the first substance, is destroyed by the excessive energy input while the first substance is retained. As a result, the recess 20 is then surrounded at the front 14 by a colored edge whose color is determined by the first material.

On the other hand, in portions with lower laser energy, which is insufficient to create a depression, or which causes a flatter depression, the first and second substances are retained. The color impression in these sections of the outline 18, the gaps 22 flatter or lacking depressions, results from the color modification of the combination of the first and the second substance. When passing through the material of the carrier 38, however, the laser energy is attenuated, whereby it comes to a change in color and not to the destruction of the second material when leaving the back 16. There are then at the back sections in which a color mark 28 is effected, which results from a change in color of the first and the second material.

If the first substance is not introduced into the coating 42 on the rear side 16, the color effect is effected exclusively by the second substance. In gaps 32 therebetween which correspond to the shallower or missing pits in the gaps 22 which have been subjected to lower intensity laser radiation, the color effect is different. If only the second material was used, for example, its color effect can be omitted. For example, if the first and second fabrics have been used in the coating 42, the color effect of the first fabric may be absent and that of the second fabric may be absent. The result is a color-structured outline 18 on the rear side 16, which was structured exclusively by the variation of the intensity of the laser radiation during the irradiation from the front side 14 with regard to their multicolor.

Fig. 5 shows a possible embodiment of the security feature of the front 14 and the back 16, in which only two different markings are generated in an outline 18. The embodiment of the Fig. 5 is thus a simplification of the version according to Fig. 2 , On the front side 14, either a gap 22 is generated by the laser radiation, that is, in cross-section, the embodiment according to FIG Fig. 3c realized, or a recess 20, so the embodiment according to Fig. 4 , At the back 16 is accordingly in the outline 18, a gap 32, the colored edge corresponding to the edge 50 of Fig. 3c has, or a color mark 28, which the color zone 56 of the Fig. 4 equivalent.

Fig. 5 shows at the front side 14 for the letter "P" a regular sequence of depressions 20 and gaps 22, for the letter "L" an at least partially irregular sequence to illustrate that both variants are possible.

The gaps 22 are generated with a laser beam energy which is higher than that for the production of the depressions 20. In other words, the contour line 18 is formed with a locally varying energy along the contour of the laser radiation 34. Correspondingly, the sequence of gaps 32 with colored edge 50 and color markings 28 corresponding to the color zones 56 then appears on the rear side 16.

Of course, the variation in intensity may also cause the color effect on the colored edge 50 of the gaps 32 to differ in color from the color effect of the ink zones 56 forming the color marks 28. Then the outline 18 on the back 16 is colored in color. The same can be done additionally or alternatively on the front side 14. This is basically achieved by a substance or a combination of substances showing a different color change depending on the intensity of the laser radiation. In other words, the color change of the coating 40 and / or 42 depends on the intensity of the laser radiation.

Fig. 6 shows an embodiment similar to that of Fig. 4 , In addition to the production of the ink zone 56 and the colored edge 52 effected there by introducing the depression 54 into the carrier 38 is additionally adjacent the location at which the recess 54 is introduced, provided on the coating 40, a security thread 58 or patch or film element into which / a recess 60 is introduced by means of the laser radiation. This recess ensures that a color zone 62 forms in the coating 40 below the point at which the laser radiation is irradiated. Due to the different material composition of the security thread 58 relative to the carrier 38, the security thread 58 reacts differently to the laser radiation. In the example shown the Fig. 6 the conditions are such that the recess 54 and the recess 60 were generated with identical laser beam parameters and still result in different depths. This facilitates the laser control.

Due to the weakening of the security thread 58 in the region of the recess 60, the ink zone 62 is clearly visible from above. The same applies with appropriate transparency of the carrier 38 from the bottom.

Fig. 7 shows a modification of the construction of Fig. 3c , wherein now on the front side 14 no coating 40 is provided. In other words, the carrier 38 is provided only on the back 16 with the coating 42. Accordingly, the colored edge 40 results only in the area of the hole 24 and only on the rear side 16 of the carrier 38. This embodiment can, as in Fig. 7 shown, optionally supplemented by the fact that on the front side 14 again a security thread 58, patch or film element is applied, in / by means of the laser radiation, a hole 64 is incorporated, which extends as a recess 66 in the carrier 38. The laser radiation results in turn on the back 16, a color zone 68 in exact Passerung to the hole 64 in the security thread 58th

Fig. 8 shows a combination of the features of the embodiments of FIGS. 6 and 7 , The coating 40 is thus located on the front side 14, so that the laser radiation around the hole 24 forms colored edges 52 on the front side and 50 on the rear side of the carrier 38. At the same time, a security thread 58, patch or film element is arranged on the front side 14 on the coating 40 into which the laser radiation has introduced the hole 64, which extends into the carrier 38 as a depression 66. In modification to the situation of Fig. 7 As a result, not only the color zone 68 on the rear side 16 but also a color edge 70, which surrounds the hole 64 or the recess 66, is formed. This color edge 70 and the ink zone 68 are in exact register to the hole 64th

LIST OF REFERENCE NUMBERS

10

bill

12

safety feature

14

front

16

back

18

outline

20

deepening

22

gap

24

hole

26, 26 '

motive

28

color coding

30

colored border

32

gap

34

laser radiation

36

incidence direction

38

carrier

40

coating

42

coating

44

edge

46

edge

48

flank

50

colored border

52

colored border

54

deepening

56

color zone

58

security thread

60

depression

62

color zone

64

hole

66

deepening

68

color zone

70

color edge

A1

Workspace

A2

Workspace

B1

holewidth

C1

Color border width

C2

Color border width

D1

offset

D2

expansion

E1

energy threshold

E2

energy threshold

E3

energy threshold

Claims (14)

Method for producing a security feature (12) for a security element, a security paper or a data carrier, wherein a carrier (38) is provided which has a front side (14) and a rear side (16), - The support (38) is provided with a coating (42) which is modifiable by laser radiation (34) in terms of their color, and the thickness of the carrier (38) is locally changed by the action of laser radiation (34) which is intensely distributed in the beam cross section, wherein at the same time the coating (42) is modified by the laser radiation (34) in terms of color, characterized in that - The support (38) on its rear side (16) with the coating (42) is provided and - The laser radiation (34) from the front side (14) is irradiated to the carrier (38), wherein a hole (24) in the carrier (38) is generated as a local change in thickness and a zone (52) due to the intensity distribution over the beam cross section, which surrounds one edge (46) of the hole (24) on the back (16) of the carrier (38) is modified in color. Method for producing a security feature (12) for a security element, a security paper or a data carrier, wherein a carrier (38) is provided which has a front side (14) and a rear side (16), - The carrier (38) is provided with a coating (42) which is modifiable by laser radiation (34) in terms of their color, the thickness of the carrier (38) is locally changed by the action of laser radiation (34) which is intensely distributed in the beam cross section, - wherein at the same time the coating (42) by the laser radiation (34)) is modified in terms of color, characterized in that - The support (38) on its rear side (16) with the coating (42) is provided and - The laser radiation (34) from the front side (14) on the support (38) is irradiated, wherein the change in thickness is a recess (20) on the front side (14) of the carrier and a zone (56) on the back ( 16) of the carrier (38) below the recess (20) is modified in terms of color. The method of claim 1 and / or 2, characterized in that the carrier (38) is also provided on its front side (14) with a coating (40) by the laser radiation (34) in terms of their color is modifiable such that even a zone (50) surrounding the edge (44) of the hole (24) or recess (20) on the front side (14) of the carrier (38) is modified in color. A method according to claim 3, characterized in that the carrier (38) is a banknote paper and that on the front side (14) a security film (58), in particular a security thread or patch is applied, in the means of the laser radiation (34) a recess (60) is introduced, so that under this recess (60), the coating (42) on the front side 14 of the carrier (38) is modified in terms of color. Method according to one of claims 1 to 4, characterized in that the coating (40) of the front side (14) performs a color change in the modification, which differs from that of the coating (42) on the back (16). A method according to claim 1, characterized in that the carrier (38) is a banknote paper and that on the front side (14) a security thread (58) is applied, in which by means of the laser radiation (34) a hole (64) is introduced, the as a recess (66) in the carrier (38), wherein also below the coating (42) on the back (16) of the carrier (38) is modified in terms of color. Security feature for a security element, a security paper, or a volume that has: a support (38) having a front side (14) and a back side (16), - wherein the carrier (38) is provided with a coating (42) which is modifiable by laser radiation (34) in terms of their color, - By means of laser radiation (34), the carrier (38) is locally changed in thickness, and - wherein the coating (42) is modified by laser radiation (34) in terms of color, characterized in that - The carrier (38) on its rear side (16) with the coating (42) is provided and - The local change in thickness is by means of the laser radiation (34) from the front side (14) in the carrier (38) produced hole (24), wherein a zone (52) having an edge (46) of the hole (24) on the Surrounds back (16) of the carrier (38), is modified by the laser radiation (34) in terms of color. Security feature for a security element, a security paper, or a volume that has: a support (38) having a front side (14) and a back side (16), - wherein the carrier (38) is provided with a coating (42) which is modifiable by laser radiation (34) in terms of their color, - By means of laser radiation (34), the carrier (38) is locally changed in thickness, and - wherein the coating is modified by laser radiation (34) in terms of color, characterized in that - The carrier (38) on its rear side (16) with the coating (42) is provided and - The local change in thickness by means of the laser radiation (34) from the front side (14) in the carrier (38) generated recess (20), wherein a zone on the back (16) of the carrier (38) under the recess (20 ), is modified by the laser radiation (34) in terms of color. Security feature according to claim 7 and / or 8, characterized in that the carrier (38) is also provided on its front side (14) with a coating (40) which is modifiable by the laser radiation (34) in terms of their color, so that also a zone (50) surrounding an edge (44) of the hole (24) or recess (20) on the front face (14) of the carrier (38) is modified in color. Security feature according to claim 9, characterized in that the carrier (38) is a banknote paper and that on the front side (14) a security film or a security thread (58) is applied, in which by means of the laser radiation (34) introduced a recess (60) is, where also under this recess (60), the coating (40) on the front side (14) of the carrier (38) is modified in terms of color. Security feature according to one of claims 7 to 10, characterized in that the coating of the front side (14) in the modification performs a color change, which differs from that of the coating on the back (16). Security feature according to claim 7, characterized in that the carrier (38) is a banknote paper and that on the front side (14) a security film or a security thread (58) is applied, in which by means of the laser radiation (34) introduced a hole (64) which extends as a recess (66) in the carrier (38), below which the coating (42) on the back (16) of the carrier (38) is modified in terms of color. Security paper with a security feature (12) according to one of claims 7 to 12. Security document or data carrier, in particular banknote (10) or identity card, with a security paper according to claim 13.

Images