METHOD AND DEVICE FOR INSERTING A LASER-GRADED SAFETY MARK

Description

[0001] The invention relates to a device and a method for embedding a laser-etched security feature into a blank of an identification, valuables, or security document comprising a flat surface. The invention also relates to a security feature and an identification, valuables, or security document with such a security feature.

[0002] Identification, security, or other documents serve to verify the identity of a person or object, or a claim, such as for payment of a sum of money, delivery of a product, or provision of a service. To this end, it must be ensured that the document cannot be imitated, forged, or altered, or only with considerable effort. Therefore, the document often contains security features that are extremely difficult or even practically impossible to replicate. For example, like banknotes, the document may be made of a material that is not readily available. Additionally or alternatively, security features can be created using special inks, such as luminescent or optically variable inks; optical elements, such as ambiguous images, kinegrams, lens or prism arrays; as well as guilloches, melier fibers, security threads, and other methods.Furthermore, it is often necessary that the identification, value or security documents are easy to produce and that they can be read by visually impaired persons.

[0003] German patent application DE 10 2012 219 249 A1 describes a device for laser personalization of security elements. This device has a laser and a focus adjustment device to vary the focal length. It also includes a planar field optic. WO 2006 / 128607 describes a vector laser marker for marking data carriers. DE 10 2018 005 990 A1 describes a laser processing device for generating a combined laser beam with independently adjustable width. DE 10 2008 028 705 A1 describes a device for producing a valuable and / or security document. WO 2015 / 040055 A1 describes a device for producing a security feature and a valuable or security product, in which several laser beams are combined into a single laser beam.

[0004] Although many security features exist, many forgeries of identity documents, valuables, or security documents are still successful.

[0005] It is therefore the object of the present invention to provide a device, a method, a security feature and an identification, value and security document which possess increased protection against forgery.

[0006] This problem is solved by a device having the features of claim 1, by a method having the features of claim 9, by a security feature having the features of claim 14, and by an identification, value, or security document having the features of claim 15. Advantageous embodiments with expedient further developments of the invention are specified in the dependent claims.

[0007] The device according to the invention comprises a holder for receiving or fixing the blank in position. It further comprises a laser source for emitting a laser beam. A lens arrangement is also provided, comprising at least one electrically movable lens and thus configured to shape the laser beam emitted by the laser source. A mirror arrangement is provided, comprising at least one electrically adjustable mirror and thus configured to deflect the laser beam exiting the lens arrangement. A further lens arrangement is provided, which serves to diffract or focus the laser beam deflected by the adjustable mirror, such that the diffracted or focused laser beam strikes the blank substantially perpendicular to its surface.The device comprises a control device for controlling the movable lens of the lens arrangement, preferably a combination of one convex and one concave lens or vice versa, and the adjustable mirror of the mirror arrangement, wherein the control device is configured as follows: . a) to acquire and / or process reference values ​​in the form of three-dimensional topography data, b) to cause the mirror arrangement to scan the blank in an area intended for the security feature with the laser beam and thereby introduce the security feature by means of the laser beam, and c) to adjust the laser beam depending on its point of impact on the flat surface with regard to its focal length or with regard to its diameter based on the reference values, while maintaining the distance between the surface of the blank and the further lens arrangement.

[0008] In this way, the already known laser-based marking processes can be enhanced by adding another parameter: the beam diameter that strikes the workpiece. This also entails a shift of the focal point based on given reference values. Here, the lens arrangement is used as a kind of defocusing unit ("focus shifter") to achieve variable beam expansion and thus variable modulation of the laser beam, depending on reference values ​​that are defined, for example, by the grayscale levels themselves, by a grayscale image, by a logo, or by another type of three-dimensional structure. The degree of defocusing or the degree of beam expansion is a measure of the line width imprinted on the workpiece; or dot width, if the laser is a pulsed laser.The defocusing unit can alternatively or additionally generate at least one variable beam divergence, as a result of which the object-side focus distance varies.

[0009] It has proven advantageous if the lens arrangement includes a galvanometric motor for moving the at least one movable lens, as this is characterized by its low inertia and thus by rapid adjustability.

[0010] To ensure that the laser beam strikes the newly formed surface of the blank to be marked as perpendicularly as possible, it has proven advantageous for the additional lens arrangement to include a plane-field lens. An equally reliable perpendicular alignment is also possible with a further lens arrangement in the form of a telecentric F-theta lens.

[0011] It has proven advantageous if the at least one adjustable mirror in the mirror assembly is also adjustable by means of a galvanometric motor. This motor is also very responsive, enabling fast, reliable, and precise deflection of the laser beam. The mirror assembly can, for example, also include two different mirrors, with a first deflection mirror causing deflection in the X-direction and a second adjustable mirror causing deflection in the Y-direction. The adjustment of the laser beam in the Z-direction, i.e., the adjustment of the actual focus of the laser beam relative to the blank, is achieved by the lens assembly with its movable lens.

[0012] Processing and counterfeit protection are enhanced when an optical detection device is present to optically capture information already present on the blank, and when the control device is configured to use the optically captured information in the form of reference values ​​for adjusting the laser beam. The blank can therefore already be marked with individualized information, such as a photograph, from which a corresponding data set in the form of reference values ​​is generated to allow X / Y / Z mapping of the laser beam.

[0013] Preferably, this is personal information, and it is advisable if the extracted information relates to the personal data of the (future) holder of the identification, security, or other document. Alternatively, the information extracted from the blank can also relate to document-specific data of the identification, security, or other document to be created.

[0014] The advantages and beneficial effects described in connection with the device according to the invention apply equally to the method according to the invention, in particular because it is carried out with the device according to the invention.

[0015] The method according to the invention is defined in claim 9.

[0016] Here too, the "defocusing unit," in the form of the lens assembly with its adjustable lens, is used to achieve beam modulation, particularly with regard to the Z-value. Thus, depending on the X and Y coordinates—that is, depending on the point where the laser beam strikes the flat surface of the blank—different Z-values ​​are used to focus the laser beam. In this way, wider or narrower laser beams will strike the surface of the blank, depending on the previously stored reference values. The ability to defocus allows for the implementation of an additional laser-applied security feature.

[0017] It is advantageous if a focal length of the laser beam, predetermined by the reference values, is set for each point on the surface of the blank.

[0018] To further increase protection against counterfeiting, it has proven advantageous to take the reference values ​​from another piece of information contained on the identification, security or insurance document.

[0019] Preferably, this is personal information, and it is advisable if the extracted information relates to the personal data of the (future) holder of the identification, security, or other document. Alternatively, the information extracted from the blank can also relate to document-specific data of the identification, security, or other document to be created.

[0020] The advantages and beneficial effects described in connection with the inventive method apply equally to a security feature produced according to the inventive method, as well as to an identification, value or security document according to the inventive method which is equipped with such a security feature.

[0021] Examples of acceptable identification, security, or other documents include a passport, identity card, driver's license or other ID card or access control card, vehicle registration certificate, vehicle title, visa, check, other means of payment, in particular a banknote, check, bank, credit or cash payment card, customer card, health card, chip card, company ID, proof of authorization, membership card or other ID document.

[0022] Preferably, the identification, valuables, or security document is in ID 1, ID 2, ID 3, or any other format, for example, in booklet form, similar to a passport-like item. The identification, valuables, or security product is generally a laminate of several document layers that are precisely bonded together under heat and increased pressure. These products should meet standardized requirements, such as ISO 10373, ISO / IEC 7810, and ISO 14443.

[0023] Preferably, the product layers consist of a carrier material suitable for lamination. The identification, value, or security document may, however, preferably be formed from a polymer selected from the group comprising polycarbonate (PC), in particular bisphenol A polycarbonate or a polycarbonate formed with a geminal disubstituted bis(hydroxyphenyl) cycloalkane, polyethylene terephthalate (PET), its derivatives such as glycol-modified PET (PETG), polyethylene naphthalate (PEN), polyvinyl chloride (PVC), polyvinyl butyral (PVB), polymethyl methacrylate (PMMA), polyimide (PI), polyvinyl alcohol (PVA), polystyrene (PS), polyvinylphenol (PVP), polypropylene (PP), polyethylene (PE), thermoplastic elastomers (TPE), in particular thermoplastic polyurethane (TPU), acrylonitrile butadiene styrene copolymer (ABS), and its derivatives, and / or paper and / or cardboard and / or glass and / or metal and / or ceramics.Furthermore, the product can also be made from several of these materials. Preferably, it consists of PC or PC / TPU / PC. The polymers can be either filled or unfilled. In the latter case, they are preferably transparent or translucent. If the polymers are filled, they are opaque. The foregoing refers both to films to be bonded together and to liquid formulations that are applied to a precursor, such as a protective or topcoat. Preferably, the product is made from three to twelve, more preferably four to ten films. The films can also bear printed layers. A laminate formed in this way can finally be coated on one or both sides with the protective or topcoat or with a film. The film can, in particular, be a scratch-resistant film. Overlay layers formed in this way protect an underlying security feature and / or give the document the required abrasion resistance.

[0024] Preferably, the identification, valuables, or security document has a PE substrate onto which the photopolymer film, exposed with the hologram, is applied. The photopolymer can, for example, be formed from a one-component monomer selected from benzoyl ether, acetophenone, benzoyl oxime, and acylphosphine. Alternatively, the photopolymer can be based on a two-component system whose components are selected from benzophenone, xanthone, and quinone.

[0025] Further features, properties, and advantages of the present invention are described in more detail below with reference to exemplary embodiments and the accompanying figures. All features described so far and below are advantageous both individually and in any combination. The exemplary embodiments described below are merely examples and do not limit the scope of the invention. The following are shown: Fig. 1 a schematic representation of the device according to the invention for introducing a laser-etched security feature into a blank of an identification, value or security document comprising a flat surface, Fig. 2 an exemplary indication of beam expansion or defocusing of the laser, which is based on the reference values ​​in the form of a reference image (not according to the invention), both for pulsed laser operation and for a continuous-wave laser, Fig. 3 one of the Figure 2 corresponding representation of the beam expansion or defocusing of the laser, which is based on reference values ​​in the form of gray levels (not according to the invention), and Fig. 4 one of the Figure 2 corresponding representation of the beam expansion or defocusing of the laser, which is based on the reference values ​​according to the invention in the form of three-dimensional topography data.

[0026] In Figure 1A device 100 for embedding a laser-etched security feature into a blank 200 of an identification, valuables, or security document comprising a flat surface 202 is shown. The device includes a holder 124 for receiving the blank 200 and fixing it in position. The device also includes a laser source 102 for emitting a laser beam 104. Furthermore, a lens arrangement 106 is provided, which in this case acts as a defocusing unit and comprises at least one electrically movable lens 108. It is configured to shape the laser beam 104 emitted by the laser source 102. On the exit side, a mirror arrangement 112 is provided, which includes at least one electrically adjustable mirror and is thus configured to deflect the laser beam 104 exiting the lens arrangement 106.In the present mirror arrangement 112, several adjustable mirrors 114 are also provided, one of which is configured as a deflection mirror in the X-direction and the other as a deflection mirror in the Y-direction. Furthermore, an additional lens arrangement 118 is provided for diffracting the laser beam 104 deflected by the adjustable mirror 114 such that the diffracted or deflected laser beam 104 strikes the blank 200 substantially perpendicular to its surface 202. In this case, the additional lens arrangement 118 is formed by a plane-field lens, in particular by an F-theta lens 120.

[0027] The adjustment of the lens arrangement 106, in particular its movable lens 108, is realized in this case by a galvanometric motor 110. The rotation of the at least one adjustable mirror 114 of the mirror arrangement 112 is also realized by a galvanometric motor 116. The F-theta lens 120 is fixed relative to the blank 200.

[0028] Furthermore, a control device 126 is provided for controlling the movable lens 108 of the lens assembly 106 and the adjustable mirror 114 of the mirror assembly 112. This control device 126 is configured to acquire and / or process reference values ​​122. It is also configured to cause the mirror assembly 112 to scan the blank 200 in an area designated for the security feature with the laser beam 104 and thereby introduce the security feature by means of the laser beam 104. It also causes the laser beam 104 to be adjusted according to its focal length or diameter based on the reference values, depending on its point of impact on the flat surface 202, while maintaining the distance between the surface 202 of the blank 200 and the further lens assembly 118, in particular the F-theta lens 120.In this way, the focus of the laser beam "wanders" along the Z-values ​​of the reference values ​​122, resulting in different beam expansion or different beam diameters on the flat surface 202 of the laser beam, and thus enabling an individualized laser-etched security feature to be incorporated into the blank 200.

[0029] For additional individualization, an optional optical detection device 128 is also available to optically detect information already present on the blank 200, whereby the control device 126 is also set up to use the optically detected information in the form of reference values ​​122 for adjusting the laser beam 104.

[0030] During the processing of the blank 200, a focal length (Z) of the laser beam 104 is specified for each point (X, Y) on the surface 202 of the blank 200, defined by the reference values. These reference values ​​are taken from further information contained on the identification, security, or other document using the optical detection device 128. The extracted information may, for example, be personal data of the (future) holder of the identification, security, or other document. Alternatively or additionally, the information extracted from the blank 200 may also be document-specific information.

[0031] In Figure 2The illustration shows, purely as an example, the beam expansion or defocusing of a laser beam 104, based on reference values ​​122 in the form of a reference image. The stronger the gray value or color, the greater the effect in the Z-direction, i.e., the change in the focal length of the laser beam. This results in larger beam diameters, which, at a given distance from the F-theta lens 120, provide the security feature on the flat surface 202. The laser can be a pulsed laser, with the use of a picosecond or femtosecond laser being advantageous because these result in low heat input into the material of the blank 200. In the illustration shown, the use of a pulsed laser is reflected in individual circles, which can also overlap and which have different diameters depending on the Z-value of the reference values ​​122.If a continuous-wave laser is used, the resulting line is also illustrated, and its line width varies depending on the reference values ​​122.

[0032] In Figure 3 The beam expansion is illustrated as a function of the available gray levels, with a darker shade of gray resulting in a greater focal length of the laser beam 104 than a lighter one. Thus, each shade of gray is assigned its own focal length, which also allows the different beam diameters at the point of impact on the workpiece to be identified, a safety feature in the blank 200.

[0033] Finally, by Figure 4It is further illustrated that three-dimensional topographic data can also be used as reference values ​​122, whereby the focus of the laser beam 104 then follows the surface of the reference values ​​in the Z-direction. Using this three-dimensional topographic data as reference values ​​122 also makes it possible to implement more complex security features. It is also possible to provide a different relationship, which does not necessarily have to be proportional. For example, a non-linear relationship in the sense of a game gradation or an inversion is possible.

[0034] As a result, the present invention is characterized by increased counterfeit protection of the security features and opens up new processing options. An identification document, valuables document, or security document produced with such a security feature is also more counterfeit-proof.

[0035] It should be added that the energy of the applied laser pulses does not necessarily have to be constant. It is possible that the desired material interaction fails to occur at large incident beam diameters because the quotient of "energy per area" (= fluence), or the irradiance "power per area," decreases with the square of the diameter of the incident beam and may no longer be sufficient (threshold fluence). With Gaussian beams, the diameter of the interaction can therefore decrease with increasing beam diameter, contrary to expectations. For this reason, another variant of the described method allows for the implementation of active pulse energy tracking to ensure that the energetic interaction between the material and the incident laser beam remains largely constant. This implementation can take the form of a parameterizable fluence compensation.

[0036] It is possible to dispense with an f-theta lens and achieve the planar field by deflecting the prefocused beam. In this case, the inverse function of the normally spherical focus area is interpolated onto the focus shifter. The object types mentioned should then be understood as offsets on the spherical correction matrix, with otherwise identical functionality. REFERENCE MARK LIST

[0037] 100 Device for inserting a laser-etched security feature 102 Laser source 104 Laser beam 106 Lens assembly 108 Sliding lens 110 Motor (lens assembly) 112 Mirror assembly 114 Adjustable mirror 116 Motor (mirror assembly) 118 Additional lens assembly 120 F-theta lens / F-theta objective 122 Reference values ​​124 Mount 126 Control device 128 Optical detection device (e.g., camera) 200 Blank of the identification, value, or security document 202 Surface

Claims

1. A device (100) for introducing a laser-engraved security feature into a blank (200) of an identity, value, or security document comprising a flat surface (202), comprising: - a holder (124) for receiving or fixing the position of the blank (200), - a laser source (102) for emitting a laser beam (104), - a lens arrangement (106) comprising at least one electrically motor-driven lens (108) and designed to shape the laser beam (104) emitted by the laser source (102), - a mirror arrangement (112) comprising at least one electrically motor-driven adjustable mirror (114) and designed to deflect the laser beam (104) emerging from the lens arrangement (106), - a further lens arrangement (118) for deflecting the laser beam (104) deflected by the adjustable mirror (114) in such a way that the diffracted laser beam (104) strikes the blank (200) substantially perpendicular to its surface (202), and - a control device (126) for controlling the movable lens (108) of the lens arrangement (106) and the adjustable mirror (114) of the mirror arrangement (112), wherein the control device (126) is designed: a) to acquire and / or process reference values (122) in the form of three-dimensional topography data, b) causing the mirror arrangement (112) to scan the blank (200) in a region provided for the security feature with the laser beam (104), thereby introducing the security feature by means of the laser beam (104), and c) adjusting the laser beam (104) in terms of its focal length or diameter based on the reference values depending on its point of impact on the flat surface (202) while maintaining the distance between the surface (202) of the blank (200) and the further lens arrangement (118).

2. The device (100) according to claim 1, characterized in that the lens arrangement (118) comprises a galvanometric motor (110) for displacing the at least one displaceable lens (108).

3. The device (100) according to claim 1 or 2, characterized in that the further lens arrangement (118) comprises a piano-field lens.

4. The device (100) according to any one of claims 1 to 3, characterized in that the further lens arrangement (118) is a telecentric F-theta lens (120).

5. The device (100) according to any one of claims 1 to 4, characterized in that at least one adjustable mirror (114) is adjustable by means of a galvanometric motor (116).

6. The device (100) according to any one of claims 1 to 5, characterized in that an optical detection device (128) is provided to optically detect information present on the blank (200), and in that the control device (126) is designed to use the optically detected information in the form of reference values (122) to adjust the laser beam (104).

7. A method using a device according to claim 6, characterized in that the information taken relates to personal data of the holder of the identity, value, or security document.

8. A method using a device according to claim 6, characterized in that the information taken relates to document-specific data of the identity, value, or security document to be created.

9. A method for incorporating a laser-engraved security feature into a blank (200) of an identity, value, or security document comprising a flat surface (202) using a device (100) according to any one of claims 1 to 8, comprising the steps: - providing or capturing reference values in the form of three-dimensional topography data, and - scanning the blank (200) with the laser beam (104) in an area designated for the security feature, wherein the laser beam (104) is modulated for the purpose of introducing the security feature on the basis of the reference values with regard to the focal length or with regard to the diameter, while maintaining the distance between the additional lens arrangement (118) and the surface (202) of the blank (200).

10. The method according to claim 9, characterized in that for each point (X, Y) on the surface (202) of the blank (200), a focal length (Z) of the laser beam (104) specified by the reference values is set.

11. The method according to claim 9 or 10, characterized in that the reference values are taken from further information contained on the identity, value, or security document.

12. The method according to claim 11, characterized in that the information taken relates to personal data of the holder of the identity, value, or security document.

13. The method according to claim 11, characterized in that the information taken relates to document-specific data of the identity, value, or security document to be created.

14. A security feature for an identity, value, or security document, produced according to the method to any one of claims 9 to 13.

15. An identity, value, or security document with a security feature according to claim 14.