METHOD FOR UNMISTAKABLE MARKING OF OBJECTS

Description

[0001] The invention relates to a method for uniquely marking an object, wherein a random distribution of individual pigment domains is applied to a surface of the object, and wherein a list of distances between the individual pigment domains is measured and stored in a database, and a corresponding method for identifying an object.

[0002] To individually mark and identify an object, it is known to mark each individual object with a suspension of fluorescent or phosphorescent pigments. The suspension is so thin or low-concentrated that only a few pigment particles or pigment domains are present in the coating. The distribution of the pigment domains is random. The random pattern of pigment domains can be used to uniquely identify the individually marked object. The special feature of random marking with pigment domains is that the random patterns cannot be copied economically. It is also known to mark banknotes or securities in this way in order to produce counterfeit- and copy-proof notes.

[0003] To increase counterfeit security, it is also known to focus on the specific characteristics of the pigments, such as relaxation time during phosphorescence, spectral composition of fluorescence, and even the marking of the marker pigments themselves.

[0004] The marking and scanning of the produced random pattern can be performed using special recording devices. Depending on the production throughput for an object, the marking effort required for the simultaneous recording of the random pattern can place high demands on the information technology used.

[0005] To determine the authenticity of a marking, there are further developments of these marking systems in which the applied random pattern is assigned to a so-called hash, an encrypted number, by an algorithm. This number, which can be uniquely derived from the random pattern, is then cryptographically signed with a first secret key, and the signed hash is printed on the object in a machine-readable format. To verify the authenticity of the object, it is sufficient to generate this uniquely derivable number from the random pattern of the pigment domains and compare it with the signed number applied to the object. The requirements for information technology are thus kept within manageable limits.

[0006] In the context of the so-called Industry 4.0, which was in practice at the time of this application, the digitalized monitoring of all production processes, which allows all finishing steps from the original starting product to the final product to be clearly traced, it is necessary that the marking can be implemented very quickly and with little effort, and that the subsequent identification can also be carried out with a high throughput.

[0007] German patent publication DE 10 2014 207 323 B4 discloses making a random pattern and another code visible using light of different compositions. This requires a two-stage reading process, which first makes the random pattern visible, and in a subsequent step, the code is made visible.

[0008] European patent EP 2 296 911 B1 discloses applying a random pattern and a code to the object. The random pattern is encoded in a so-called hash, a sequence of characters and numbers that can be uniquely derived from the random pattern. However, the hash is not signed.

[0009] European patent application EP 2 930 699 A1 discloses applying a random pattern and a code to the object. The random pattern is encoded in a so-called hash, a sequence of characters and numbers that can be uniquely derived from the random pattern. This hash is then printed on the object in encrypted form.

[0010] European patent EP 2 296 912 B1 discloses applying a random pattern and a code to the object using an electrically conductive lacquer. Further authenticity features are incorporated into the electrically conductive lacquer.

[0011] German patent application DE 10 304 805 A1 and US patent US 7,353,994 B2 also disclose applying a random pattern and a code to the object. The random pattern is also encoded in a so-called hash, a sequence of characters and numbers that can be uniquely derived from the random pattern. This hash is then printed on the object in encrypted form.

[0012] In US patent US 7,576,842 B2, the random pattern is enhanced by a height dimension during printing, allowing the location of the individual pigment domains to be characterized with three coordinates. This increases the barrier to copying the random pattern.

[0013] In the US patent application US 2016 007 8307 A1, the random pattern of the pigment domains is further enriched by a relaxation pattern during phosphorescence.

[0014] In the US patent US 10,01,9627 B2, the random pattern of the pigment domains is further enriched by parallax-induced imaging differences.

[0015] According to the teaching of German patent DE 10 2015 219 400 B4, a random pattern of fluorescent pigment domains, once applied, is then reapplied to the object as a black and white pattern. For authenticity testing, the random pattern is compared with the printed pattern.

[0016] International patent application WO 2019 / 197 628 A1 teaches authenticity detection by comparing an applied random pattern with a stored reference image. The reference image is stored in a database.

[0017] Finally, the US patent application published as US 2011-0164748 A1 describes the production of a film with randomly distributed pigment particles. The film serves as packaging material for objects whose authenticity is to be tested. For this purpose, the random pattern is recorded in a selected area and compared with a stored pattern.

[0018] The aforementioned methods are optimized to increase the barrier to copyability by adding additional observables to the random pattern. Other methods, in turn, solve the problem of allowing authenticity verification to be performed offline, i.e., without a data connection to an authoritative database.

[0019] The object of the invention, however, is to provide a method for individual marking and a corresponding method for individual identification of an individual object that allows for high production throughput. The marking method and the identification method should be quick to implement.

[0020] The object underlying the invention is achieved by a method according to claim 1. Further advantageous embodiments are specified in the subclaims to claim 1. The identification is achieved by a method according to the dependent claim 1.

[0021] According to the concept of the invention, the following steps are provided: After the known, random distribution of pigment domains on an object, be it by painting, printing, smearing, spraying or in some other way, an image of the pigment domains is taken. This recording can be done with a generic digital camera. The recorded image is then subjected to automated analysis. The automated analysis comprises identifying the two-dimensional coordinates of each pigment domain recorded in the image. The number of pigment domains found in the recording depends on the concentration of the pigments in a varnish and a toner or in a coating. It has proven advantageous if a lower two-digit number of pigment domains is found in the recording. Identification can be supported if the pigments fluoresce or phosphoresce.The inherent luminosity allows for contrast filtering with appropriate exposure, which is so strong that the fluorescent or phosphorescent pigment domains appear as single points of light in the digital camera image. However, today's image recognition algorithms also make it possible to detect and identify non-fluorescent pigments in an image. After identifying the individual pigment domains, the two-dimensional distance of each pair of two pigment domains is determined. This results in (n 2 < + n) / 2 distances if exactly n pigment domains are present. Furthermore, each triplet of pigment domains forms a uniquely definable angle. There are m over three possibilities, calculated from m! / (3! * (m - 3)!), for determining an angle of a pigment triplet of m pigment domains. The number of mutual distances thus grows with the square of the number of identified pigment domains.The number of determinable angles grows with the mathematical factorial of the number of pigment domains. Because these numbers quickly become large, there should not be too many pigment domains in a captured image. After determining the two-dimensional distance of each pair of two pigment domains and / or determining all angles of each pigment domain triplet, the distances and / or angles determined in the previous step are saved in a list. This list is complete, as will be referred to later during identification. The list is then saved in a database, although more than one database may be present. The list is therefore saved randomly or according to an arbitrary ordering system in one of the multiple databases. When saved in the database, the list is enriched with meta information about the product's manufacturing and / or finishing parameters.Such metadata can simply be the manufacturing date and / or time. It can be a batch number, or it can be manufacturing parameters such as analysis data for a food, beverage, or medication, or test run data for a mechanical object. It can also be temperature profiles in a supply chain or chemical analysis data. The type of data is very diverse. Finally, an information unit is applied to the object, preferably in machine-readable form. The information unit can be printed or applied to the object in any other desired way, whereby the information unit can be clearly assigned to a database.

[0022] It has proven to be very advantageous if coating or printing of an ink, toner or varnish is provided for applying the random distribution of the pigment domains, wherein the ink, toner or varnish contains fluorescent or phosphorescent pigments, and wherein the concentration of the fluorescent or phosphorescent pigments in the ink, toner or varnish is such that when marking an area of ​​1 cm², between 4 and 50, preferably between 4 and 20 pigment domains are applied. The concentration to be measured depends on the printing or coating process. If more varnish, ink or toner is used in the printing or coating process, the concentration of pigments can be correspondingly lower, and vice versa.

[0023] Marking with an information unit can either disrupt the aesthetic appearance of the object or affect its function. For this purpose, the use of an ink, toner, or varnish to apply the information unit can be considered. Due to its color and / or transparency, the ink, toner, or varnish, once applied, is invisible to the human eye under normal lighting conditions, or at least not perceptible at first glance. This means that the marking does not overlap with other markings, such as EAN codes, unique codes used to mark consumer products, which simplify inventory in retail and identification of the object at the checkout.

[0024] In a particular embodiment of the method, it can be provided that the ink, toner or varnish fluoresces or phosphoresces when stimulated by irradiation with light in the visual range from 380 nm to 780 nm, preferably in the range of light with a wavelength between 380 nm and 500 nm, particularly preferably in the range between 400 nm and 470 nm. The fluorescence or phosphorescence is therefore triggered by light in the visual range. Pigments that fluoresce or phosphoresce when irradiated with violet light or blue light are suitable for this purpose. The use of such pigments has the advantage that illumination to make the pigment domains or the information unit visible can be achieved with visual light, thus preventing a user from blinding or damaging their eyes when handling the light source. Especially with very high product throughput, the UV dose for the user is reduced.

[0025] Depending on the requirements of the retail trade or the production chain, it may be advantageous if at least parts of the information unit can be deleted or even deleted entirely. For this purpose, the use of an ink, toner or varnish can be provided which bleaches when irradiated with light in the UV-C to UV-B range, preferably with light with a wavelength in the range of 240 nm to 380 nm, particularly preferably by irradiation with light with a wavelength in the range of 240 nm to 315 nm. This bleaching enables relabeling or linking the object to a new database that is relevant after product finishing. Alternatively or cumulatively, the use of an ink, toner or varnish that can be thermally bleached can be provided. This can be used to prove that, for example, a beverage in a closed can has been properly pasteurized.Fluorescent or phosphorescent pigments that can be thermally bleached at temperatures between 80°C and 120°C are suitable for bleaching, so that heating to this temperature bleaches the ink, toner or varnish.

[0026] Up to this point, the individual marking steps and the advantageous embodiments of the marking method have been explained. After marking, identification follows later. The previously marked object is now identified as follows: by irradiating the pigment domains with light in the visual VIS range in the range of a wavelength of light from 380 nm to 780 nm, preferably with light in the range of light with a wavelength between 380 nm and 500 nm, particularly preferably with light in the range of light with a wavelength in the range between 400 nm and 470 nm. The object is therefore irradiated with visual light, preferably blue light. The pigment domains become visible when they fluoresce and / or phosphoresce. This is followed by taking an image of the pigment domains. This can be done with a digital camera.The following steps are performed in the image by an algorithm for automatic image analysis: first, identifying two-dimensional coordinates of pigment domains recorded in the image and determining two-dimensional distances between pairs of pigment domains and / or determining angles spanned by pigment domain triples of the pigment domains identified in the previous step. Furthermore, reading the information unit from the surface of the object, whereby the information unit from which an identifier can be uniquely derived can be uniquely assigned to a database, and determining the resulting database. This identified database is then queried for a list containing the previously stored and coherent list of the previously determined distances and / or angles, whereby the database outputs the corresponding data set.The meta information is read from the data set.

[0027] During identification, it may be possible to query all determined distances and / or angles of the pigment domains in the database. However, a subset of distances and / or angles can also be queried. The previously described identification method is thus supplemented by the following steps: determining a number of n pigment domains from a number of m identified pigment domains, where n is less than m and where the n pigment domains are the brightest pigment domains upon irradiation, and querying the database with n distances from (m 2 < - m) / 2 possible distances and / or querying k angles from m! / (3! * (m - 3)!) possible angles, where n and k are preferably greater than 4.Surprisingly, it has been found that starting with just four distances, the variation in the random patterns due to the number of distances and angles becomes so extremely large that when querying which previously stored complete list in the database contains the almost arbitrarily determined n distances and / or k angles, the variation arises partly from the choice of more than one database and partly from the random distance patterns and / or angle patterns of the n brightest pigment domains. If the number of databases is sufficiently large so that sufficiently few individual objects are stored in each individual database, the identification of the object also becomes sufficiently individual.

[0028] The entire marking and identification process allows the use of a commercially available mobile phone with a camera and lamp or a tablet computer with a camera and lamp to carry out the identification process. The lamp of the camera or tablet computer to be used emits white light and / or light in the visual VIS range from 380 nm to 780 nm, preferably light with a wavelength between 380 nm and 500 nm, particularly preferably light with a wavelength in the range between 400 nm and 470 nm. The lamp of today's cameras and tablet computers often has a high blue component. This involves the following steps: illuminating the pigment domains with the light of the lamp and recording the pigment domains with the camera, and finally carrying out the further method steps recited in claim 6 with the mobile phone or tablet computer.The use of a mobile phone or tablet computer is suitable for identifying an object, for example, by an end customer. In high-throughput manufacturing processes, suitable industrial cameras would be used for this purpose.

[0029] Since not all objects have flat surfaces, it may be necessary to apply the random pattern of pigment domains to a curved surface. This is the case, for example, with cans, bottles, or semi-finished products without a flat surface. To clearly identify these objects, compensation optics can be used to compensate for the curvature of the surface. For this purpose, the compensation optics are adapted to the curvature of the object. Depending on the performance of the camera optics, the compensation optics can either only compensate for the curvature and create a flat image of the curved surface, or adjust a macro lens setting of the camera optics so that the very shallow depth of field of the camera optics is adapted to the curved surface.

[0030] Alternatively or in addition to the compensation optics, a macro lens can also be used as an auxiliary lens in order to be able to image the usually quite small markings, which are in the range of 1 cm 2< to 2 cm 2<, well and close up.

[0031] In a particular embodiment of the method according to the invention, the information unit can consist of the presence of certain fluorescent and / or phosphorescent colors in the pigment domains. If the marking is to be read using a commercially available mobile phone or tablet computer, at least three color channels are available, which the camera can clearly distinguish. If markings are used that use one of three colors, two of three colors, or all three colors, it is possible to create seven color combinations from these in order to perform a database assignment. High-quality mobile phone cameras can also clearly distinguish between multiple colors, so that when using n colors, a total of 2n< color combinations can be created, which can be used as database assignment parameters.

[0032] The invention is explained in more detail with reference to the following figures. They show: Fig. 1a standard beverage can with applied QR code as an example of an object without a flat surface, Fig. 2the beverage can from Figure 1 with a view of the concave bottom with inverse half-calotte in perspective view, Fig. 3 a view of the inverse half-calotte from Figure 2 in a top view with a sketch to illustrate the connection between marking and database, Fig. 4 an example of a random coating with a pigment-containing ink as an enlarged detail A, Fig. 5 the random coating from Figure 4 with marked distances of selected pigment domains, Fig. 6Connection of a commercially available mobile phone with a beverage can from the Figures 1 and 2 via a compensation optic, Fig. 7 an isolated compensation optic from Fig. 6 , Fig. 8a diagram to illustrate the classification of light spectra with different wavelength ranges.

[0033] In Figure 1A commercially available beverage can is depicted as object 100 with an applied QR code as an example of an object without a flat surface. The QR code, as an information unit 140, which can be made invisible to the human eye, or at least barely perceptible, by selecting a fluorescent ink, a fluorescent varnish, or a fluorescent toner, can contain information that identifies a database containing data about this individual can. Different databases can be different database servers in different locations around the world, different database programs on the same server, or even data records within a database that form a coherent data record as a virtual database through a common data record, such as an identification ID.

[0034] In Figure 1It is shown that the surface 101 of the can as object 100 does not have a flat surface.

[0035] In Figure 2 the beverage can is made of Figure 1 Shown in perspective with a view of the concave base with an inverted half-dome. The inverted half-dome is inserted into the can, as is the case with bottles, to better withstand the pressure inside the can. Instead of the can jacket, a QR code can also be printed on the curved can base.

[0036] In Figure 3 is a view of the inverse hemisphere from Figure 2shown in a top view with a sketch to illustrate the relationship between the marking and the database. The can, as object 100, has a concave surface 101 on its bottom. Applied to this surface in the area of ​​detail A is a print or coating with a toner, varnish, or ink containing fluorescent or phosphorescent pigments. An information unit is printed across the surface of detail A. In this example, the information unit is not shown as a QR code, but as a 7-segment representation, which is also machine-readable. The information unit contains, for example, a number "765," which serves as an identifier for one or more databases. Detail A contains fluorescent or phosphorescent pigments.When capturing an image 130 of detail A with the pigment domains 110 present there, the X and Y coordinates of each pigment domain are determined, as are the distances ΔXY between each pair of pigment domains. The determined distances are summarized in a list 120 and stored in a database, here, for example, database DB765. The content of information unit 140 is directly assignable to database DB765.

[0037] In Figure 4 is an example of a random coating with a pigment-containing ink as enlarged detail A from Figure 3 shown, with detail A captured as image 130. The coating can be random, like a brushstroke, but can also be linear and repeatably defined. This depends on the choice of marking technique. Within the coating of ink 150 are pigment domains 110 that are randomly distributed in size and position.

[0038] In Figure 5 is the random coating of Figure 4 with the ΔXY distances of selected pigment domains marked. Only those distances are shown here whose connecting line does not intersect with any other connecting line. As a result, fewer connecting lines are shown than there are possible ΔXY distances according to (m 2 < - m) / 2, where m is the number of pigment domains. To identify this can, it is possible to query the database DB765, selected here as an example, to find a complete list with all (m 2 < - m) / 2 distances marked here.

[0039] In Figure 6 is a connection of a commercially available mobile phone 200 with a beverage can as object 100 from the Figures 1 and 2via a compensation optics 300. The lens of the camera 210 of the commercially available mobile phone 200 is enabled, via the compensation optics 300, which contains a compensation lens 303, to read both the pigment domains 110 (not shown here) and the information unit 140 (also not shown) from the curved bottom of the can as object 100 from an extreme proximity.

[0040] In Figure 7A compensation optics 300 is shown, which is designed here for use with a commercially available mobile phone 200. A mounting ring 301, which can be made of rubber or plastic, has a lamp recess 102 inside so that the lamp of the commercially available mobile phone 200 can illuminate the bottom of the can as object 100. Furthermore, the compensation optics 300 has a compensation lens 303, which, in the mounted state, is arranged directly above the camera lens of the camera 210 and, like glasses or an additional lens, enables the camera lens to view and sharply image the extremely closely arranged and curved bottom of the can as object 100.

[0041] In Figure 8Finally, a diagram 400 is shown to illustrate the classification of light spectra with different wavelength ranges. At the center of its entire wavelength range, light has a visual VIS range 401, namely starting at a wavelength of 380 nm up to a wavelength of 780 nm. The excitation of the fluorescent and / or phosphorescent pigment particles is to occur within this visual VIS range. The visual VIS range 401 is followed, for longer wavelengths, by a near IR-A infrared range 402, which ranges from 780 nm wavelength to 1,400 nm wavelength, followed by a far IR-B infrared range from 1,400 nm wavelength to 3,000 nm wavelength. In the short-wavelength range, the VIS range 401 is adjacent to the UV-A range 402, which ranges from 315 nm to 380 nm. The UV-A range 404 is followed towards shorter wavelengths by a UV-B range 405 with a wavelength interval of 280 nm to 315 nm.The UV-C range 406 follows, with a wavelength range from 100 nm to 280 nm. In this range, a light source can emit light to optionally bleach the information unit 140. LIST OF REFERENCE SYMBOLS 100 object 403 IR-B 101 surface 404 UVA 110 Pigment domain 405 UVB 120 list 406 UVC 130 Picture 140 Information unit α angle 150 ink A detail 200 mobile phone DB1 1. Database 210 camera DB2 2. Database 220 lamp DB3 3. Database 300 Compensation optics DBj j. Database 301 Mounting ring DB765 765. Database 302 Lamp recess DBk k. database 303 compensation lens ΔXY Distance 400 spectrum X coordinate 401 VIS Y coordinate 402 IR-A

Claims

1. A method for clearly marking an object (100), wherein a random distribution of individual pigment domains (110) is applied to a surface (101) of the object (100), and wherein a list (120) of distances (ΔXY) of the individual pigment domains (110) from each other is measured and stored in a database (DB1, DB2, DB3, DBj, DB765, DBk), with the following steps: - Recording an image (130) of the pigment domains (110), - Identifying the two-dimensional coordinates (X, Y) of each of the pigment domains (110) recorded in the image (130), - Determining the two-dimensional distances (ΔXY) of each pair of two pigment domains (110), and / or - Determining the angle (α) of each triple of pigment domains, - Storing the distances (ΔXY) and / or angles (α) determined beforehand in one of the steps in a list (120), - Storing the list (120) in the database (DB765), characterized in that the list (120) is enriched with meta information about the manufacturing and / or refining parameters of the object (100), as well as by - Applying a database identification as the information unit (140) onto the surfaces (101) of the object (100), wherein the information unit (140) can clearly be allocated to the database (DB765).

2. The method according to claim 1, characterized by painting or printing an ink (150), a toner or a varnish for applying the random distribution of pigment domains (110), wherein the ink (150), the toner or the varnish has fluorescent or phosphorescent pigments, wherein the concentration of fluorescent or phosphorescent pigments in the ink (150) in the toner or in the varnish is metered in such a way as to apply between 4 and at most 50, preferably between 4 and at most 20 pigment domains (110) while marking a surface of 1 cm2.

3. The method according to claim 1 or 2, characterized by using an ink (150), a toner or a varnish for applying the information unit (140), wherein the ink (150), the toner or the varnish is invisible to the human eye in the applied state, or at least not perceptible at first glance, under the usual lighting conditions for human sight by virtue of its color and / or its transparency.

4. The method according to claim 3, characterized in that the ink (150), the toner or the varnish fluoresces or phosphoresces when excited by irradiation from light in the visual range of 380 nm to 780 nm, preferably within a range of light having a wavelength of between 380 nm and 500 nm, especially preferably within a range of between 400 nm and 470 nm.

5. The method according to one of claims 3 or 4, characterized by - using an ink (150), a toner or a varnish which fades when irradiated with light in the UV-C range (406) to UV-B range (405), preferably with light having a wavelength ranging from 240 nm to 380 nm, especially preferably when irradiated with light having a wavelength within a range of 240 nm to 315 nm.

6. The method according to one of claims 1 to 5, characterized in that the information unit (140) is given by the combination of fluorescent and / or phosphorescent colors present in the pigment domains (110).

7. A method for identifying an object, which has been marked based on the method according to one of claims 1 to 6, characterized by - Irradiating the pigment domains (110) with light in the visual VIS range (401) of 380 nm to 780 nm, preferably with light within the range of light having a wavelength of between 380 nm and 500 nm, especially preferably with light within a range of light having a wavelength ranging from 400 nm to 470 nm, - Recording an image (130) of the pigment domains (110), - Identifying two-dimensional coordinates (X, Y) of pigment domains (110) recorded in the image (130), - Determining two-dimensional distances (ΔXY) between pairs of pigment domains (110) of the pigment domains (110) identified in the preceding step, and / or - Determining angles (α) spanned by three pigment domains, - Reading out the information unit (140) from the surface (101) of the object (100), wherein the information unit (140) can be clearly allocated to a database (DB765), and determining the resultantly arising database (DB765), - Querying the previously identified database (DB765), which has the previously determined distances (ΔXY) in the coherent list (120) previously stored in the database (DB765), wherein the database (DB765) outputs the corresponding dataset, - Reading out the meta information from the dataset.

8. The method according to claim 7, characterized by subsequently irradiating the information unit (140) with light having a wavelength in the UV-C range (406) to UV-B range (405), preferably within a light wavelength range of 240 nm to 380 nm, especially preferably within a wavelength range of the light having a wavelength of 240 nm to 315 nm, so that the information unit (140) fades and / or the information unit (140) is heated to a temperature of between 80 °C and 120 °C, so that the information unit (140) fades.

9. The method according to claim 7, characterized by - Determining a number of n pigment domains (110) form a number m of identified pigment domains (110), wherein n is less than m, and wherein the n pigment domains (110) are the brightest pigment domains (110) during irradiation, - Querying the database (DB765) with n distances (ΔXY) out of (m2-m) / 2 possible distances (ΔXY), wherein n is preferably greater than 4, and / or - Querying the database (DB765) with k angles (α) out of m! (3! * (m-3)!) possible angles (α).

10. The method according to claim 7, characterized by - Using a mobile telephone (200) or a tablet computer equipped with a camera (210) and lamp (220), wherein the lamp (220) emits light in the visual VIS range (401) of 380 nm to 780 nm, preferably light having a wavelength of between 380 nm and 500 nm, especially light having a wavelength within a range of between 400 nm and 470 nm, - Illuminating the pigment domains (110) with the light of the lamp (220), - Recording the pigment domains (110) with the camera (210), and - Implementing the other procedural steps mentioned in claim 7 with the mobile telephone (200) or the tablet computer.

11. The method according to one of claims 6 to 10, characterized by - Using compensation optics (300) for recording the image (130), wherein the compensation optics (300) compensate for a surface (101) of the object (100) deviating from the plane, and / or - Using a microlens as the attachment lens for recording the image (130).

12. The method according to one of claims 6 to 11, characterized by - Calculating the surface (101) of the object (100) deviating from a plane, wherein a predetermined location with a predetermined shape is assumed for the location of the random distribution of individual pigment domains (110) on the surface (101) of the object (100).