CA2671611C - Security element having an optically variable element - Google Patents
Security element having an optically variable element Download PDFInfo
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- CA2671611C CA2671611C CA2671611A CA2671611A CA2671611C CA 2671611 C CA2671611 C CA 2671611C CA 2671611 A CA2671611 A CA 2671611A CA 2671611 A CA2671611 A CA 2671611A CA 2671611 C CA2671611 C CA 2671611C
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- substrate
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- pigment
- pigments
- optically variable
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
- B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
- B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
- B42D25/30—Identification or security features, e.g. for preventing forgery
- B42D25/36—Identification or security features, e.g. for preventing forgery comprising special materials
- B42D25/378—Special inks
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
- B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
- B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
- B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
- B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
- B42D25/20—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof characterised by a particular use or purpose
- B42D25/29—Securities; Bank notes
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
- B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
- B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
- B42D25/30—Identification or security features, e.g. for preventing forgery
- B42D25/36—Identification or security features, e.g. for preventing forgery comprising special materials
- B42D25/373—Metallic materials
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B42—BOOKBINDING; ALBUMS; FILES; SPECIAL PRINTED MATTER
- B42D—BOOKS; BOOK COVERS; LOOSE LEAVES; PRINTED MATTER CHARACTERISED BY IDENTIFICATION OR SECURITY FEATURES; PRINTED MATTER OF SPECIAL FORMAT OR STYLE NOT OTHERWISE PROVIDED FOR; DEVICES FOR USE THEREWITH AND NOT OTHERWISE PROVIDED FOR; MOVABLE-STRIP WRITING OR READING APPARATUS
- B42D25/00—Information-bearing cards or sheet-like structures characterised by identification or security features; Manufacture thereof
- B42D25/40—Manufacture
- B42D25/405—Marking
- B42D25/41—Marking using electromagnetic radiation
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- B42D2035/24—
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- Business, Economics & Management (AREA)
- Accounting & Taxation (AREA)
- Finance (AREA)
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Electromagnetism (AREA)
- General Health & Medical Sciences (AREA)
- Toxicology (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Credit Cards Or The Like (AREA)
- Printing Methods (AREA)
- Laminated Bodies (AREA)
Abstract
The invention relates to a substrate (1) having a safety element (2) comprising at least one optically variable color (3) having pigments (4). The individual pigments have at least one multi-layer design that is capable of interference. According to the invention, the pigments (4) of the optically variable color of the safety element (2) are irreversibly modified in at least one partial region (6) by means of electromagnetic radiation (5) such that the interference effect is visually and/or mechanically clearly recognizably modified, or completely eliminated in this partial region (6).
Description
Security Element Having an Optically Variable Element The present invention relates to a substrate having a security element that exhibits at least one optically variable ink having pigments. The individual pigments here consist of at least one interference-capable, multilayer structure.
To protect against reproduction, especially with color copiers or other reproduction methods, data carriers, such as banknotes or cards, are furnished with optically variable security elements. Here, the counterfeit protection is based on the fact that the visually and easily and distinctly perceptible optically variable effect can not, or only inadequately, be reproduced by the above-mentioned reproduction devices.
Optically variable security elements include, for example, thin-film elements that consist of a reflector layer, a dielectric and an absorber layer. If the security element is observed from the absorber side, the viewer perceives a certain color that changes when the viewing angle changes.
The cause of the color shift is an interference effect between the light beams that are reflected by the surface of the partially transmissive outer layer (absorber layer) and the light beams that pass through the partially transmissive outer layer and the middle dielectric layer and are reflected back by the inner metal reflector layer to the partially transmissive layer.
At the partially transmissive layer, the light beams are then either transmitted outward or reflected again such that, in this case, the light beams are reflected multiply back and forth between the reflection layer and the partially transmissive layer. The light beams that passed through the thin-film layer have thus covered a longer path than the light beams reflected off
To protect against reproduction, especially with color copiers or other reproduction methods, data carriers, such as banknotes or cards, are furnished with optically variable security elements. Here, the counterfeit protection is based on the fact that the visually and easily and distinctly perceptible optically variable effect can not, or only inadequately, be reproduced by the above-mentioned reproduction devices.
Optically variable security elements include, for example, thin-film elements that consist of a reflector layer, a dielectric and an absorber layer. If the security element is observed from the absorber side, the viewer perceives a certain color that changes when the viewing angle changes.
The cause of the color shift is an interference effect between the light beams that are reflected by the surface of the partially transmissive outer layer (absorber layer) and the light beams that pass through the partially transmissive outer layer and the middle dielectric layer and are reflected back by the inner metal reflector layer to the partially transmissive layer.
At the partially transmissive layer, the light beams are then either transmitted outward or reflected again such that, in this case, the light beams are reflected multiply back and forth between the reflection layer and the partially transmissive layer. The light beams that passed through the thin-film layer have thus covered a longer path than the light beams reflected off
-2-the surface of the thin-film layer, such that they are phase-shifted with respect to these reflected beams when they interfere with them.
If the light beams incident on the thin-film layer strike the thin-film layer at different angles of incidence, then the path covered by the light beams in the thin-film layer has different lengths. This difference results from the changed path difference, due to the angle of incidence, of the beams that are reflected multiply within the thin-film layer. That is why the phasing of the interfering light beams differs depending on the angle of incidence, such that, depending on the angle of incidence, different colors or tones of the resulting light beam perceived by the viewer result.
Such thin-film elements can be used in the form of foils, as described, for example, in WO 2005/108110. From WO 2005/108110 is known a security element having a thin-film layer in which the individual layers are arranged contiguously on the security element. By the action of laser radiation, markings are introduced into the layer sequence in the form of patterns, letters, numbers or images. For this, the layer sequence includes a marking layer composed of an ink mixture that exhibits a mixture component that absorbs the laser radiation, and one that is transparent to the laser radiation.
The identifiers are visually and/or machine-perceptible due to an irreversible change in the optical properties of the ink mixture, effected by the action of the laser radiation.
Likewise, pigmentary thin-film elements are known that are added to a printing ink. EP 0 227 423 B1 describes thin-film elements having a symmetric structure to ensure that the pigment looks the same from each side. Each of the thin-film elements consists of a five-layer thin-film that is assembled from an inner metal reflector layer, a dielectric layer arranged
If the light beams incident on the thin-film layer strike the thin-film layer at different angles of incidence, then the path covered by the light beams in the thin-film layer has different lengths. This difference results from the changed path difference, due to the angle of incidence, of the beams that are reflected multiply within the thin-film layer. That is why the phasing of the interfering light beams differs depending on the angle of incidence, such that, depending on the angle of incidence, different colors or tones of the resulting light beam perceived by the viewer result.
Such thin-film elements can be used in the form of foils, as described, for example, in WO 2005/108110. From WO 2005/108110 is known a security element having a thin-film layer in which the individual layers are arranged contiguously on the security element. By the action of laser radiation, markings are introduced into the layer sequence in the form of patterns, letters, numbers or images. For this, the layer sequence includes a marking layer composed of an ink mixture that exhibits a mixture component that absorbs the laser radiation, and one that is transparent to the laser radiation.
The identifiers are visually and/or machine-perceptible due to an irreversible change in the optical properties of the ink mixture, effected by the action of the laser radiation.
Likewise, pigmentary thin-film elements are known that are added to a printing ink. EP 0 227 423 B1 describes thin-film elements having a symmetric structure to ensure that the pigment looks the same from each side. Each of the thin-film elements consists of a five-layer thin-film that is assembled from an inner metal reflector layer, a dielectric layer arranged
-3-below and above and having a refractive index of 1.65 or less, and, in each case, an outer semiopaque or partially transmissive layer. In each case, on the side facing the viewer, the five-layer thin-film effects a color shift, that is, an alternation between two different colors or tones at a first and a second viewing angle. Thus, for example, the optically variable ink appears magenta from a certain viewing angle and green from another viewing angle. If a viewer tilts a data carrier on which such an optically variable ink is applied, he perceives a color shift from magenta to green or vice versa.
From WO 2005/038136 Al is a security element for security papers, value documents and the like, having a thin-film element, with a color-shift effect, that exhibits a reflection layer, an absorber layer and an intermediate layer arranged between the reflection layer and the absorber layer. Here, the intermediate layer is formed by a layer whose layer thickness, after imprinting, is locally modifiable by external influences, especially by stretching, electromagnetic radiation, electron beam treatment or the action of pressure and/or temperature. Due to the subsequent influencing of the layer thickness of the intermediate layer, a very constant layer thickness can be obtained without high precision being required in the application, especially in the printing process itself. Rather, fluctuations that occur in the layer thickness can be compensated for by a specific, local action of external influences after the application.
From EP 1 1719 636 Al is known a security element, for banknotes, value documents, tickets or as proof of authenticity, that includes a coating having at least one optically variable pigment having a significantly viewing-angle-dependent change in the color. Here, the optically variable pigment consists of vacuum-deposited thin-layer interference pigments, particles coated with interference layers or cholesteric liquid crystal pigments. In addition, the
From WO 2005/038136 Al is a security element for security papers, value documents and the like, having a thin-film element, with a color-shift effect, that exhibits a reflection layer, an absorber layer and an intermediate layer arranged between the reflection layer and the absorber layer. Here, the intermediate layer is formed by a layer whose layer thickness, after imprinting, is locally modifiable by external influences, especially by stretching, electromagnetic radiation, electron beam treatment or the action of pressure and/or temperature. Due to the subsequent influencing of the layer thickness of the intermediate layer, a very constant layer thickness can be obtained without high precision being required in the application, especially in the printing process itself. Rather, fluctuations that occur in the layer thickness can be compensated for by a specific, local action of external influences after the application.
From EP 1 1719 636 Al is known a security element, for banknotes, value documents, tickets or as proof of authenticity, that includes a coating having at least one optically variable pigment having a significantly viewing-angle-dependent change in the color. Here, the optically variable pigment consists of vacuum-deposited thin-layer interference pigments, particles coated with interference layers or cholesteric liquid crystal pigments. In addition, the
-4-optically variable pigment consists of at least one material having selectively spectrally absorbing properties, such that the optically variable pigment suppresses visible spectral components that are vertically incident on the pigment. The security element thus appears black when viewed vertically and colored when viewed grazingly.
From US 6,114,018 is known an optically variable device that exhibits a substrate having a first and a second optical device that are applied on spaced apart patches of the substrate. The first optical device consists of a first optically variable pigment, and the second optical device of a second optically variable pigment. Here, at an angle of incidence between 0 and 90 , the first and second optical device exhibit the same matching color and, for a color-matching angle and at all other angles of incidence, have no color match.
The object of the present invention is to design a security element having interference-capable pigments to be counterfeit-proof.
This object is solved by the features of the independent claims.
Developments of the present invention are the subject of the dependent claims.
Here, the present invention comprises both a substrate having a security element and a data carrier having a substrate having a security element.
Here, the data carrier is especially a value document, such as a banknote, a security paper, a credit or identification card, a passport, a certificate and the like, a label, packaging or another element for product protection.
From US 6,114,018 is known an optically variable device that exhibits a substrate having a first and a second optical device that are applied on spaced apart patches of the substrate. The first optical device consists of a first optically variable pigment, and the second optical device of a second optically variable pigment. Here, at an angle of incidence between 0 and 90 , the first and second optical device exhibit the same matching color and, for a color-matching angle and at all other angles of incidence, have no color match.
The object of the present invention is to design a security element having interference-capable pigments to be counterfeit-proof.
This object is solved by the features of the independent claims.
Developments of the present invention are the subject of the dependent claims.
Here, the present invention comprises both a substrate having a security element and a data carrier having a substrate having a security element.
Here, the data carrier is especially a value document, such as a banknote, a security paper, a credit or identification card, a passport, a certificate and the like, a label, packaging or another element for product protection.
-5-According to the present invention, the pigments of the optically variable ink of the security element are irreversibly changed in at least one sub-region by means of electromagnetic radiation in such a way that, in this sub-region, the interference effect is distinctly visually and/or mechanically perceptibly changed or entirely canceled.
The irreversible change in a pigment occurs, for one, through the change in the optical properties of at least one layer of the pigment, that is, especially in the transparency, reflectivity, polarization direction and color or tone of the pigment. For another, the irreversible change in a pigment occurs through an at least partial displacement of at least one layer of the pigment. Here, a layer of the pigment is not removed, evaporated or transformed, but rather at least partially removed from its original position within the layer structure and displaced to a new position within the layer structure. This is achieved, for example, by reducing the thickness of a layer in one patch while simultaneously increasing the thickness of a layer in another, especially in the adjacent patch.
The pigments or the pigmentary thin-film elements are preferably formed to be five-layer. They consist of a middle reflection layer, two dielectric layers surrounding the middle reflection layer on each side, and two partially transmissive outer layers. As materials for these layers, especially the following are used:
- for the middle reflection layer, all reflective substances, especially metals such as aluminum or copper, - for the dielectric layers, Si02 (silicon dioxide), Zr02 (zirconium dioxide) or Ti02 (titanium dioxide) or other transparent substances, - for the partially transmissive layers, chrome and/or nickel.
The irreversible change in a pigment occurs, for one, through the change in the optical properties of at least one layer of the pigment, that is, especially in the transparency, reflectivity, polarization direction and color or tone of the pigment. For another, the irreversible change in a pigment occurs through an at least partial displacement of at least one layer of the pigment. Here, a layer of the pigment is not removed, evaporated or transformed, but rather at least partially removed from its original position within the layer structure and displaced to a new position within the layer structure. This is achieved, for example, by reducing the thickness of a layer in one patch while simultaneously increasing the thickness of a layer in another, especially in the adjacent patch.
The pigments or the pigmentary thin-film elements are preferably formed to be five-layer. They consist of a middle reflection layer, two dielectric layers surrounding the middle reflection layer on each side, and two partially transmissive outer layers. As materials for these layers, especially the following are used:
- for the middle reflection layer, all reflective substances, especially metals such as aluminum or copper, - for the dielectric layers, Si02 (silicon dioxide), Zr02 (zirconium dioxide) or Ti02 (titanium dioxide) or other transparent substances, - for the partially transmissive layers, chrome and/or nickel.
-6-A pigment thus consists of a lower, partially transmissive layer composed of chrome and/or nickel, followed by a dielectric layer composed of silicon dioxide, a middle reflection layer composed of aluminum, which is joined by, on the opposing side, again, a dielectric layer composed of silicon dioxide, and finally, of an upper partially transmissive layer composed of chrome and/or nickel. Light that strikes on the top or bottom of the pigment is partially reflected and partially transmitted by the partially transmissive layer. The latter portion passes through the dielectric layer, which exhibits a different refractive index than the partially transmissive layer, and is reflected back by the reflection layer and, after passing through the dielectric layer, is split again into a transmitted and a reflected portion.
However, the present invention is not limited to just five-layer pigments, but rather is applicable to all one- or multilayer pigments that produce an optically variable effect. In particular, from the background art, optically variable layers are known that, starting from the reflection layer, exhibit more than two layers in the direction of the viewer. The present invention is also applicable to pigments that are manufactured from such optically variable layers and thus exhibit more than five layers.
The at least one layer changed by the electromagnetic radiation is advantageously the outermost layer of the pigment, which faces the irradiation direction. In pigments having a five-layer structure, thus the partially transmissive layer that is no longer partially transmissive after the irradiation, but rather is preferably transparent.
Influence on an interference-capable layer structure always succeeds when the reflection minimum of the interference-capable layer structure largely coincides with the wavelength of the electromagnetic radiation. Here, either
However, the present invention is not limited to just five-layer pigments, but rather is applicable to all one- or multilayer pigments that produce an optically variable effect. In particular, from the background art, optically variable layers are known that, starting from the reflection layer, exhibit more than two layers in the direction of the viewer. The present invention is also applicable to pigments that are manufactured from such optically variable layers and thus exhibit more than five layers.
The at least one layer changed by the electromagnetic radiation is advantageously the outermost layer of the pigment, which faces the irradiation direction. In pigments having a five-layer structure, thus the partially transmissive layer that is no longer partially transmissive after the irradiation, but rather is preferably transparent.
Influence on an interference-capable layer structure always succeeds when the reflection minimum of the interference-capable layer structure largely coincides with the wavelength of the electromagnetic radiation. Here, either
-7-the angle of incidence or the wavelength of the electromagnetic radiation can be adapted to the reflection minimum of the interference-capable layer structure. As is generally known, due to the change in the angle of incidence, the reflection minima shift to shorter wavelengths, such that a suitable angle at which influence on the structure occurs can nearly always be found.
If, during the irradiation with electromagnetic energy, the energy of the electromagnetic radiation is simultaneously modulated, then, particularly advantageously, a color gradient of the interference effect results, that is, different color gradients are present at different patches or at different depths in the substrate.
According to the present invention, it is not only possible to apply a single pigment ink to the substrate, but also to spread a mixture of at least two pigment inks or multiple interference layers on top of each other on the security element, of which only one exhibits a suitable reflection minimum and thus only one pigment ink is specifically changeable. Alternatively, it is furthermore possible to apply a mixture of at least one pigment ink and at least one printing ink or a further effect ink, such as an ink based on cholesteric liquid crystals or thermal inks, to the security element. Here, the further effect ink can also be applied over the pigment ink as long as it is transparent to the laser wavelength and at least in portions of the visible spectrum.
If the substrate having a security element is intended to be protected against mechanical damage, such as scratches, it is advantageous to arrange the pigment inks within two foils of a multilayer foil body. Such a multilayer foil body is, for example, a credit or identification card, the security element according to the present invention being located in the interior of the foil
If, during the irradiation with electromagnetic energy, the energy of the electromagnetic radiation is simultaneously modulated, then, particularly advantageously, a color gradient of the interference effect results, that is, different color gradients are present at different patches or at different depths in the substrate.
According to the present invention, it is not only possible to apply a single pigment ink to the substrate, but also to spread a mixture of at least two pigment inks or multiple interference layers on top of each other on the security element, of which only one exhibits a suitable reflection minimum and thus only one pigment ink is specifically changeable. Alternatively, it is furthermore possible to apply a mixture of at least one pigment ink and at least one printing ink or a further effect ink, such as an ink based on cholesteric liquid crystals or thermal inks, to the security element. Here, the further effect ink can also be applied over the pigment ink as long as it is transparent to the laser wavelength and at least in portions of the visible spectrum.
If the substrate having a security element is intended to be protected against mechanical damage, such as scratches, it is advantageous to arrange the pigment inks within two foils of a multilayer foil body. Such a multilayer foil body is, for example, a credit or identification card, the security element according to the present invention being located in the interior of the foil
-8-body and covered by a transparent foil. Of course it is also possible to cover an inventive security element on a security paper, such as a banknote, with a transparent foil.
In a further advantageous embodiment of the present invention, the substrate is printed on on the front and/or the reverse and the print is perceptible in transmitted light. This has the advantage that different information is perceptible in transmitted light and in reflected light.
Within the meaning of the present invention, viewing in reflected light is illuminating an object from one side and viewing the object from the same side. Thus, a viewing in reflected light occurs, for example, when the front of the object is illuminated and also viewed.
Within the meaning of the present invention, viewing in transmitted light is illuminating an object from one side and viewing the object from another side, especially the opposing side. Thus, a viewing in transmitted light occurs, for example, when the reverse of the object is illuminated and the front of the object is viewed. The light thus shines through the object.
According to a further advantageous embodiment of the present invention, the security element consists at least partially of a transparent foil that is printed on with the pigment inks. Here, advantageously, the irradiation occurs with electromagnetic radiation on the top of the print or on the bottom, through the transparent foil. Alternatively or additionally, the irradiation can occur with electromagnetic energy also on both sides of the foil. In reflected light, only the change caused by the irradiation on the respective side is visible, whereas in transmitted light, no information is visible any longer.
In a further advantageous embodiment of the present invention, the substrate is printed on on the front and/or the reverse and the print is perceptible in transmitted light. This has the advantage that different information is perceptible in transmitted light and in reflected light.
Within the meaning of the present invention, viewing in reflected light is illuminating an object from one side and viewing the object from the same side. Thus, a viewing in reflected light occurs, for example, when the front of the object is illuminated and also viewed.
Within the meaning of the present invention, viewing in transmitted light is illuminating an object from one side and viewing the object from another side, especially the opposing side. Thus, a viewing in transmitted light occurs, for example, when the reverse of the object is illuminated and the front of the object is viewed. The light thus shines through the object.
According to a further advantageous embodiment of the present invention, the security element consists at least partially of a transparent foil that is printed on with the pigment inks. Here, advantageously, the irradiation occurs with electromagnetic radiation on the top of the print or on the bottom, through the transparent foil. Alternatively or additionally, the irradiation can occur with electromagnetic energy also on both sides of the foil. In reflected light, only the change caused by the irradiation on the respective side is visible, whereas in transmitted light, no information is visible any longer.
-9-In a further advantageous embodiment of the present invention, the pigments are ablated or carbonized by the electromagnetic radiation. In combination with the above-described change in the pigment, this results in further design possibilities for a security element. Here, significantly higher energy densities are needed for the ablation or carbonization than for the destruction of a pigment layer.
Laser sources are preferably used as the source for the electromagnetic radiation. Here, especially pulsed Nd:YAG lasers, Nd:YVO4lasers, C02 lasers or other laser types in the wavelength range from UV to far infrared may be used as the source for the electromagnetic radiation, the lasers advantageously also often working with frequency multiplication with an average light output between 0.5 W and 2 W, thus preferably with a pulse energy between 10 J and 100 J. Particularly advantageously, laser sources in the near infrared are used, since this wavelength range is well suited to the absorption properties of the substrates and printing inks used for value documents. For example, it is easy to specify for this range printing inks that are transparent to the laser radiation, but opaque and colored to the human viewer in the visible spectral range. Particularly advantageously, infrared lasers in the wavelength range from 0.8 tum to 3gm, especially Nd:YAG
lasers or Nd:YVO4lasers, are used. If lasers with higher output are used, then the pulse energy can be reduced to the required amount through masking, beam splitting, absorption filters, defocusing or si.milar known methods. Alternatively, the laser frequency can be increased accordingly.
With a Nd:YAG marking laser (A = 1.064 m), vectors, for example, can be inscribed in the layer sequence, which is advantageous above all for fast inscriptions. For this, a Nd:YAG laser can be operated with a pulse
Laser sources are preferably used as the source for the electromagnetic radiation. Here, especially pulsed Nd:YAG lasers, Nd:YVO4lasers, C02 lasers or other laser types in the wavelength range from UV to far infrared may be used as the source for the electromagnetic radiation, the lasers advantageously also often working with frequency multiplication with an average light output between 0.5 W and 2 W, thus preferably with a pulse energy between 10 J and 100 J. Particularly advantageously, laser sources in the near infrared are used, since this wavelength range is well suited to the absorption properties of the substrates and printing inks used for value documents. For example, it is easy to specify for this range printing inks that are transparent to the laser radiation, but opaque and colored to the human viewer in the visible spectral range. Particularly advantageously, infrared lasers in the wavelength range from 0.8 tum to 3gm, especially Nd:YAG
lasers or Nd:YVO4lasers, are used. If lasers with higher output are used, then the pulse energy can be reduced to the required amount through masking, beam splitting, absorption filters, defocusing or si.milar known methods. Alternatively, the laser frequency can be increased accordingly.
With a Nd:YAG marking laser (A = 1.064 m), vectors, for example, can be inscribed in the layer sequence, which is advantageous above all for fast inscriptions. For this, a Nd:YAG laser can be operated with a pulse
-10-frequency of, for example, 20 kHz, an output between 0.5 W and 2 W, and a diameter of the focus of the laser between 70 m and 300 m, particularly advantageously 100 m and 200 m. The working distance between the lens and the substrate is chosen to be somewhat lower than required for optimum focusing in order to achieve a slight defocusing of the laser spot. With a pulse, if the focus diameter is chosen to be larger than the advantageous setting, then, with a uniform energy distribution in the beam (top hat) and appropriately higher pulse energy, also larger surface areas can be changed and thus the inscription speed increased at the expense of the resolution.
If the laser is chosen to be energetically modulatable from pulse to pulse, then a color gradient of the interference effect can be achieved. Here, different color gradients are present at different patches or at different depths in the substrate. In addition, with appropriate energy control, the pigment or absorbing ink components can be completely or partially ablated/carbonized without effort.
The substrate having the security element according to the present invention serves especially to increase the counterfeit security of value documents such as banknotes, checks, stocks, identity cards, admission tickets, transportation tickets, certificates, credit cards, bank cards and the like.
The substrate having the security element according to the present invention is especially combinable with any other security feature within a value document. For example, the substrate having the security element according to the present invention can, for example, be applied over a security thread, be combined with a hologram or diffractive patterns, or be arranged next to or overlapping with other optically variable patterns.
If the laser is chosen to be energetically modulatable from pulse to pulse, then a color gradient of the interference effect can be achieved. Here, different color gradients are present at different patches or at different depths in the substrate. In addition, with appropriate energy control, the pigment or absorbing ink components can be completely or partially ablated/carbonized without effort.
The substrate having the security element according to the present invention serves especially to increase the counterfeit security of value documents such as banknotes, checks, stocks, identity cards, admission tickets, transportation tickets, certificates, credit cards, bank cards and the like.
The substrate having the security element according to the present invention is especially combinable with any other security feature within a value document. For example, the substrate having the security element according to the present invention can, for example, be applied over a security thread, be combined with a hologram or diffractive patterns, or be arranged next to or overlapping with other optically variable patterns.
-11-The advantages of the present invention and different preferred embodiments of the present invention will be explained with reference to the following examples and supplementing drawings. In detail, depicted schematically are:
Fig. 1 A substrate having an inventive security element composed of an optically variable ink having pigments, in side view;
Fig. 2 The layer structure of an individual pigment in side view, and here, Fig. 2a before irradiation with electromagnetic energy and Fig. 2b after irradiation with electromagnetic energy;
Fig. 3 A substrate having an inventive security element in top view, and here, Fig. 3a in reflected light and Fig. 3b in transmitted light.
For the sake of better comprehensibility, the embodiments described in the following examples are reduced to the essential core information and the illustrations in the drawings are highly schematized and do not reflect the real conditions. Above all, the proportions shown in the figures do not correspond to the actual ratios and serve solely to improve clarity. In practical implementation, significantly more complex patterns or images in single- or multicolor printing can be used as a coating. The information depicted in the following examples can likewise be replaced by any complex image or text information.
The examples depict preferred embodiments, to which, however, the present invention is in no way intended to be limited. In particular, the different exemplary embodiments are also not limited to the use in the form
Fig. 1 A substrate having an inventive security element composed of an optically variable ink having pigments, in side view;
Fig. 2 The layer structure of an individual pigment in side view, and here, Fig. 2a before irradiation with electromagnetic energy and Fig. 2b after irradiation with electromagnetic energy;
Fig. 3 A substrate having an inventive security element in top view, and here, Fig. 3a in reflected light and Fig. 3b in transmitted light.
For the sake of better comprehensibility, the embodiments described in the following examples are reduced to the essential core information and the illustrations in the drawings are highly schematized and do not reflect the real conditions. Above all, the proportions shown in the figures do not correspond to the actual ratios and serve solely to improve clarity. In practical implementation, significantly more complex patterns or images in single- or multicolor printing can be used as a coating. The information depicted in the following examples can likewise be replaced by any complex image or text information.
The examples depict preferred embodiments, to which, however, the present invention is in no way intended to be limited. In particular, the different exemplary embodiments are also not limited to the use in the form
-12-described, but rather can also be combined with each other to increase the effects.
In a preferred exemplary embodiment, according to fig. 1, a security element 2 is arranged on a surface of a substrate 1. Here, the security element 2 consists of an optically variable ink 3 in which the pigments 4 are embedded.
A sub-region 6 of the optically variable ink 3 is irradiated by electromagnetic energy, for example in the form of a laser beam 5.
As the optically variable ink 3, for example the ink OVI 9Z 3050A from Sicpa is used with pigments from Flex, with a color change from magenta to green, or the corresponding ink OVI 9Z 1050 with a color change from gold to green.
In fig. 2, a lateral cross section through a pigment 4 is depicted. According to fig. 2a, the pigment 4 that is still uninfluenced by the laser beam 5 consists of a middle reflection layer 7, a dielectric layer 81 on its bottom, a dielectric layer 82 on its top, and a partially transmissive layer 91 on the dielectric layer 81 and a partially transmissive layer 92 on the dielectric layer 82. The partially transmissive layer 92 lies on the side of the pigment 4 facing the laser beam 5, whereas the partially transmissive layer 91 is covered by the reflection layer 7. According to fig. 2b, with suitable irradiation intensity and wavelength of the light of the laser beam 5, if a laser beam 5 now strikes the pigment 4, only the partially transmissive layer 92 is influenced. Here, in particular, the optical properties of the partially transmissive layer 92 are changed, such that, for example, the transmission capacity of the partially transmissive layer 92 is increased, that is, the color change is altered.
Preferably, the partially transmissive layer 92 is nearly completely transparent, such that the viewer perceives only the color of the reflection
In a preferred exemplary embodiment, according to fig. 1, a security element 2 is arranged on a surface of a substrate 1. Here, the security element 2 consists of an optically variable ink 3 in which the pigments 4 are embedded.
A sub-region 6 of the optically variable ink 3 is irradiated by electromagnetic energy, for example in the form of a laser beam 5.
As the optically variable ink 3, for example the ink OVI 9Z 3050A from Sicpa is used with pigments from Flex, with a color change from magenta to green, or the corresponding ink OVI 9Z 1050 with a color change from gold to green.
In fig. 2, a lateral cross section through a pigment 4 is depicted. According to fig. 2a, the pigment 4 that is still uninfluenced by the laser beam 5 consists of a middle reflection layer 7, a dielectric layer 81 on its bottom, a dielectric layer 82 on its top, and a partially transmissive layer 91 on the dielectric layer 81 and a partially transmissive layer 92 on the dielectric layer 82. The partially transmissive layer 92 lies on the side of the pigment 4 facing the laser beam 5, whereas the partially transmissive layer 91 is covered by the reflection layer 7. According to fig. 2b, with suitable irradiation intensity and wavelength of the light of the laser beam 5, if a laser beam 5 now strikes the pigment 4, only the partially transmissive layer 92 is influenced. Here, in particular, the optical properties of the partially transmissive layer 92 are changed, such that, for example, the transmission capacity of the partially transmissive layer 92 is increased, that is, the color change is altered.
Preferably, the partially transmissive layer 92 is nearly completely transparent, such that the viewer perceives only the color of the reflection
- 13 -layer 7. If this reflection layer is formed to be metallic or silver-matte or shiny, then the pigment 4 appears to the viewer to be only silver.
The laser beam 5 thus changes the partially transmissive layer 92 of the optically variable ink 3. In this way, an alteration in the color change is achieved, for example to silver, a portion of the optically variable effect being maintained depending on the irradiation intensity of the laser beam 5. The lower the irradiation intensity of the laser beam 5 is, the more the optically variable effect is maintained.
According to fig. 3a, the patch that is influenced by the laser beam 5 is distinctly perceptible when viewed in reflected light, for example as a silver patch having an altered color change, or as an exclusively silver patch without further color change. In contrast, the adjacent regions of the optically variable ink 3 that were not influenced by the laser beam 5 continue to exhibit a color change in reflected light. A contrast thus results between regions having an altered color change and regions having an unaltered color change.
If the optically variable ink 3 is printed on a partially or completely transparent substrate, then according to fig. 3b, when viewed in transmitted light, the optically variable ink appears in a nearly uniform tone, for example uniformly gray, both in the patches that are influenced by the laser beam 5 and in the uninfluenced patches. The patch that is influenced by the laser beam 5 thus does not stand out from the uninfluenced regions in transmitted light, since pigments were influenced by the laser beam 5 only in individual layers, whereas the nearly nontransparent reflection layer 7 remains uninfluenced. Thus, the total transmission capacity, or the optical density, of the pigments was not changed.
The laser beam 5 thus changes the partially transmissive layer 92 of the optically variable ink 3. In this way, an alteration in the color change is achieved, for example to silver, a portion of the optically variable effect being maintained depending on the irradiation intensity of the laser beam 5. The lower the irradiation intensity of the laser beam 5 is, the more the optically variable effect is maintained.
According to fig. 3a, the patch that is influenced by the laser beam 5 is distinctly perceptible when viewed in reflected light, for example as a silver patch having an altered color change, or as an exclusively silver patch without further color change. In contrast, the adjacent regions of the optically variable ink 3 that were not influenced by the laser beam 5 continue to exhibit a color change in reflected light. A contrast thus results between regions having an altered color change and regions having an unaltered color change.
If the optically variable ink 3 is printed on a partially or completely transparent substrate, then according to fig. 3b, when viewed in transmitted light, the optically variable ink appears in a nearly uniform tone, for example uniformly gray, both in the patches that are influenced by the laser beam 5 and in the uninfluenced patches. The patch that is influenced by the laser beam 5 thus does not stand out from the uninfluenced regions in transmitted light, since pigments were influenced by the laser beam 5 only in individual layers, whereas the nearly nontransparent reflection layer 7 remains uninfluenced. Thus, the total transmission capacity, or the optical density, of the pigments was not changed.
-14-The impression of a nearly uniforxnly gray and thus not completely opaque, black surface results when viewed in transmitted light, since - the thickness of the security element 2 and/or the number of pigments 4 in the optically variable ink 3 based on a volume unit is formed to be so low that light can shine through the gap between the individual pigments 4 and/or - the reflection layer 7 of the pigments 4 is formed to be semitransparent, such that light that falls on the side of the substrate 1 that faces away from the security element 2 can shine through the pigment 4.
Claims (15)
1. A substrate (1) having a security element (2) that exhibits at least one optically variable ink (3) having pigments (4), the individual pigments (4) exhibiting at least one interference-capable, multilayer structure, characterized in that the pigments (4) of the optically variable ink of the security element (2) are irreversibly changed in at least one sub-region (6) by means of electromagnetic radiation (5) in such a way that, in this sub-region (6), the interference effect is distinctly visually and/or mechanically perceptibly changed compared with adjacent regions having no change in the pigments, the irreversible change in a pigment (4) occurring through the change in the optical properties of the outermost layer of the pigment (4), which faces the irradiation direction.
2. The substrate (1) according to claim 1, characterized in that the irreversible change in a pigment (4) occurs through an at least partial displacement of at least one layer of the pigment (4).
3. The substrate (1) according to claim 1 or 2, characterized in that the pigments (4) are formed to be five-layer and consist of a middle reflection layer (7), two dielectric layers (81, 82) surrounding the middle reflection layer (7) on each side, and two partially transmissive outer layers (91, 92).
4. The substrate (1) according to claim 3, characterized in that the inner reflection layer (7) consists of aluminum, and/ or that at least one of the dielectric layers (81, 82) consists of silicon dioxide, and/or that the partially transmissive outer layers (91, 92) consist of at least chrome and/or nickel.
5. The substrate (1) according to claim 3 or 4, characterized in that the electromagnetic radiation (5) irreversibly changes at least the partially transmissive layer (92) of a pigment (4).
6. The substrate (1) according to any one of claims 1 to 5, characterized in that the pigment inks are arranged within two foils of a multilayer foil body.
7. The substrate (1) according to claim 6, characterized in that the multilayer foil body is a credit or identification card or a passport.
8. The substrate (1) according to any one of claims 1 to 7, characterized in that the security element (2) at least partially consists of a transparent foil.
9. The substrate (1) according to any one of claims 1 to 8, characterized in that a laser delivers the electromagnetic radiation (5).
10. A data carrier having a substrate (1) according to any one of claims 1 to 9.
11. The data carrier according to claim 10, characterized in that the data carrier is a value document, a banknote or a card.
12. A method for manufacturing a substrate (1) having a security element (2) on which at least one optically variable ink (3) having pigments (4) is imprinted, the individual pigments (4) being formed from at least one interference-capable, multilayer structure, characterized in that the pigments (4) of the optically variable ink of the security element (2) are irreversibly changed in at least one sub-region (6) by means of electromagnetic radiation (5) in such a way that, in this sub-region (6), the interference effect is distinctly visually and/or mechanically perceptibly changed, the irreversible change in a pigment (4) occurring through the change in the optical properties of the outermost layer of the pigment (4), which faces the irradiation direction.
13. The method for manufacturing a substrate (1) according to claim 12, characterized in that the wavelength of the electromagnetic radiation (5) is adapted to the reflection minimum of the interference-capable layer structure.
14. The method for manufacturing a substrate (1) according to claim 12, characterized in that the reflection minimum of the interference-capable layer structure is adapted to the wavelength of the electromagnetic radiation (5) through the angle of incidence.
15. The method for manufacturing a substrate (1) according to any one of claims 12 to 14, characterized in that a grayscale-modulated image is produced through a modulation of the energy of the electromagnetic radiation (5).
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE102006062281A DE102006062281A1 (en) | 2006-12-22 | 2006-12-22 | Substrate for use with safety feature, has pigments of optically variable color of safety features that are irreversibly changed in partition by electromagnetic radiation |
| DE102006062281.2 | 2006-12-22 | ||
| PCT/EP2007/010578 WO2008080499A1 (en) | 2006-12-22 | 2007-12-06 | Safety element having an optically variable element |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2671611A1 CA2671611A1 (en) | 2008-07-10 |
| CA2671611C true CA2671611C (en) | 2015-08-11 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA2671611A Expired - Fee Related CA2671611C (en) | 2006-12-22 | 2007-12-06 | Security element having an optically variable element |
Country Status (7)
| Country | Link |
|---|---|
| EP (1) | EP2104618B1 (en) |
| AU (1) | AU2007341700B2 (en) |
| CA (1) | CA2671611C (en) |
| DE (1) | DE102006062281A1 (en) |
| PL (1) | PL2104618T3 (en) |
| RU (1) | RU2429978C2 (en) |
| WO (1) | WO2008080499A1 (en) |
Families Citing this family (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102008028187A1 (en) * | 2008-06-12 | 2009-12-17 | Giesecke & Devrient Gmbh | Security element with optically variable element. |
| DE102009058603A1 (en) | 2009-12-17 | 2011-06-22 | Giesecke & Devrient GmbH, 81677 | Value document system and method of manufacturing the same |
| DE102010006173A1 (en) | 2010-01-29 | 2011-08-04 | Giesecke & Devrient GmbH, 81677 | Security element with extended color shift effect and thermochromic additional function |
| FR2961621B1 (en) * | 2010-06-22 | 2014-09-05 | Arjowiggins Security | METHOD OF AUTHENTICATING AND / OR IDENTIFYING A SECURITY ARTICLE |
| DE102011116491A1 (en) | 2011-10-20 | 2013-04-25 | Giesecke & Devrient Gmbh | Microcapsule and use of the same, microcapsules having security element and with the same equipped disk |
| EP2946938B1 (en) | 2014-05-23 | 2017-04-12 | Merck Patent GmbH | Method for the laser treatment of coatings |
| DE102017003281A1 (en) | 2017-04-04 | 2018-10-04 | Giesecke+Devrient Currency Technology Gmbh | Security element with relief structure and manufacturing method therefor |
| DE102021005870A1 (en) * | 2021-11-26 | 2023-06-01 | Giesecke+Devrient Mobile Security Gmbh | Security feature for an identification document, identification document and method for producing a security feature |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5766738A (en) * | 1979-12-28 | 1998-06-16 | Flex Products, Inc. | Paired optically variable article with paired optically variable structures and ink, paint and foil incorporating the same and method |
| EP1849620B1 (en) * | 2000-01-21 | 2016-03-23 | Viavi Solutions Inc. | Optically variable security devices |
| DE10349000A1 (en) * | 2003-10-17 | 2005-05-19 | Giesecke & Devrient Gmbh | Security element with color shift effect |
| EP1719636A1 (en) * | 2005-05-04 | 2006-11-08 | Sicpa Holding S.A. | Black-to-color shifting security element |
-
2006
- 2006-12-22 DE DE102006062281A patent/DE102006062281A1/en not_active Withdrawn
-
2007
- 2007-12-06 WO PCT/EP2007/010578 patent/WO2008080499A1/en active Application Filing
- 2007-12-06 RU RU2009127521/12A patent/RU2429978C2/en not_active IP Right Cessation
- 2007-12-06 AU AU2007341700A patent/AU2007341700B2/en not_active Withdrawn - After Issue
- 2007-12-06 EP EP07847008.5A patent/EP2104618B1/en not_active Not-in-force
- 2007-12-06 CA CA2671611A patent/CA2671611C/en not_active Expired - Fee Related
- 2007-12-06 PL PL07847008T patent/PL2104618T3/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| AU2007341700B2 (en) | 2013-05-09 |
| PL2104618T3 (en) | 2014-05-30 |
| CA2671611A1 (en) | 2008-07-10 |
| EP2104618A1 (en) | 2009-09-30 |
| DE102006062281A1 (en) | 2008-06-26 |
| WO2008080499A1 (en) | 2008-07-10 |
| RU2009127521A (en) | 2011-01-27 |
| AU2007341700A1 (en) | 2008-07-10 |
| RU2429978C2 (en) | 2011-09-27 |
| EP2104618B1 (en) | 2013-11-27 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| MKLA | Lapsed |
Effective date: 20191206 |