ITEM COMPLETING FLUORESCENT MARKER ARTICLES, AND METHOD FOR IDENTIFYING THE SAME

Description

[0001] The present invention relates to an article comprising fluorescent marker particles and a method for identifying this article. TECHNICAL BACKGROUND

[0002] From the production of a product through logistics to delivery to the customer and beyond, successful product identification is essential. A variety of methods have been established for this purpose: in ancient times, engraving, which can be found, for example, in the stonemasonry marks of great old buildings; today, the tried-and-tested label with a barcode or matrix code (BAN or QR); and more recently, electronic methods such as RFID chips. The identifiers "engraving" and "label" have in common that they are visually visible and therefore relatively easy to copy. Furthermore, they alter or cover the surface of the product to be identified. While RFID chips can be installed discreetly and invisibly, they are relatively expensive, especially if they are intended to be counterfeit-proof.

[0003] Many well-known publications use fluorescent markers to authenticate products, i.e., for authenticity control. For example, DE000010322794A1 describes a sensor for authenticating a luminescent security feature. The particle position and detection are assumed to be even and flat. Similarly, DE102017004496A1 discloses luminescent pigments integrated into a printing ink to protect a printed product, such as a banknote, from counterfeiting. The advantages of fluorescent particles, such as their high luminescence intensity and high chemical stability, are emphasized, which is also described in patent DE102014011383A. DE10 2010 026627 A1 discloses the testing of an object based on a random distribution of fluorescent marker particles. The particles are randomly distributed in a partial volume of a sticker.

[0004] It is therefore the object of the present invention to provide an object and a method for its identification which overcome the disadvantages of the prior art, in particular enabling the clear, forgery-proof identification of objects without impairing the optical appearance of the object. DESCRIPTION OF THE INVENTION

[0005] This object is achieved by an article comprising fluorescent marker particles, wherein the fluorescent marker particles are distributed in the entire volume of the article or in a part of the volume of the article and the fluorescent marker particles are present in a random distribution; the volume in which the fluorescent marker particles are distributed comprises a sub-volume; the sub-volume contains at least a part of the fluorescent marker particles; the sub-volume is at least partially transparent to electromagnetic radiation with a wavelength in the visible range and / or in the near infrared range and / or in the UVA range; and a part of the surface of the sub-volume is identical to a part of the surface of the article.

[0006] Fluorescent marker particles within the meaning of the present invention are, in particular, those fluorescent marker particles that are excitable in the near infrared range and / or the UV range, preferably UVA, and emit in the visible range and / or the (preferably) near infrared range. Reference is made here to the following excitation wavelengths: UVA (380-315 nm), NIR (IR-A 780 nm-1,400 nm, preferably 980 nm), visible light VIS (380-780 nm), UV (380-100 nm), and IR (780 nm-1 nm). The use of such fluorescent marker particles enables detection with a commercially available camera, allowing the emission to be detected in both the VIS and NIR ranges without any special effort. Suitable particles are well known to the person skilled in the art, for example from the documents WO 2017 / 220079 A1 or DE 10 2014 105 846 A1.

[0007] The fluorescent marker particles are distributed either throughout the entire volume of the object or only in a portion of the object's volume. They are randomly distributed throughout this entire or partial volume. According to the invention, the entire or partial volume in which the fluorescent marker particles are present comprises a subvolume. The subvolume is a definable portion of the volume in which the fluorescent marker particles are distributed. The fluorescent marker particles are also randomly distributed within this subvolume. The random spatial particle distribution within the subvolume enables unambiguous identification of the object. Details regarding this unambiguous identification are described below in connection with the method according to the invention.

[0008] It can be provided that the fluorescent marker particles are evenly distributed throughout the volume or part of the volume of the object. In this sense, "evenly" does not mean that the particles are arranged regularly. Rather, it can be provided that approximately the same number of particles is present in the same volume unit. Within this specific volume unit, the arrangement of the particles is then random.

[0009] In one embodiment, it can be provided that the fluorescent marker particles are excitable in the near infrared range and / or in the UVA range and are emitting in the visible range and / or in the near infrared range.

[0010] In a further embodiment, the fluorescent marker particles may comprise at least two different types of fluorescent marker particles that differ from one another in terms of their size and / or shape and / or chemical composition. In this context, the chemical composition may be correlated with the fluorescence emission.

[0011] According to one embodiment, it can be provided that the object comprises a product and / or a casing, wherein the casing at least partially encloses the product. In this context, it can be provided that the casing at least partially encloses the product and the fluorescent marker particles are distributed in the product and / or the casing or a part of the product and / or the casing. According to the invention, it can also be expressly provided that the object of the present invention is a casing, for example a packaging material, a box, etc. into which a product that is not part of the object can be introduced. According to the invention, it can also be provided that the object comprises a combination of casing and product. Alternatively, it can be provided that the object is the product itself.

[0012] In one embodiment, it can be provided that the fluorescent marker particles are distributed in the casing or a part thereof and the subvolume is a part of the volume of the casing.

[0013] In a further embodiment, it can be provided that the fluorescent marker particles have an average diameter in the range of 0.1 µm to 500 µm, preferably 2 µm to 200 µm, particularly preferably 20 µm to 50 µm.

[0014] In a further embodiment, it can be provided that particles of different sizes are used. For example, it can be provided that the following average diameters can be provided for the various particles: 25 µm, 32 µm, 45 µm, 63 µm, 75 µm, 90 µm, 150 µm, and 250 µm. The individual particles of the respective fractions can be separated using a simple and cost-effective sieving process. Alternatively, it can be provided that suitable particles of different sizes are already synthesized. Ultimately, the appropriate particle size depends on the area of ​​the identification access area and the pixel resolution of the camera system. The smaller particle sizes are suitable for applications such as films, laminates, or blister packs, as well as for electronic components such as light-emitting diodes for LED chip binning control, etc., while the larger ones are suitable for housings and containers, etc.The simplest and most cost-effective implementation would be to use a 0.1 megapixel camera (320×240 pixels, so-called QVGA – currently the smallest commercially available camera chip format) (larger formats would be VGA, SVGA, XGA, etc.). Using the rule of thumb to clearly capture an idealized particle with 3×3 camera pixels and a 2-pixel edge, the particle image object width results in a particle image object width of 7 pixels. Applied to the (smaller) camera image height, 34 particles can be lined up, and converted to an identification window of 2×2 mm, this results in a particle size of 60 µm. Based on this example, larger identification windows can be defined, which can later be reliably located in the application or precisely positioned by a camera. Conversely, the required camera resolution can be calculated using a defined minimum particle size and a predefined identification fender.

[0015] In a further embodiment, the fluorescent marker particles can be suitable for emitting at least two different emission lines in the visible and / or near-infrared ranges upon excitation with an infrared source. In this context, the emission lines can be individual spectral colors or emission wavelength ranges. Preferably, fluorescent marker particles are provided that emit at approximately 470 nm, 550 nm, 670 nm (visible), and 800 nm (NIR), each within ± 20 nm.

[0016] According to a further embodiment, the fluorescent marker particles can be arranged in at least two different planes within the subvolume. An arrangement of the fluorescent marker particles in at least two different planes of the subvolume can be achieved, for example, by stacking, lamination, two-component injection molding, and other methods known from the prior art.

[0017] In one embodiment, it may be provided that the sub-volume is optically indistinguishable from at least part of the remaining object. In this context, "optically indistinguishable" means that the surface, color, and / or material properties are identical and / or the optical refractive index of the materials is identical or differs by no more than ± 15%.

[0018] In a further embodiment, it can be provided that the sub-volume has a thickness of 0.5 µm to 500 µm, alternatively 0.5 mm to 5 mm. According to the invention, it is provided that the sub-volume is arranged on the surface of the object, i.e. that part of the surface of the sub-volume is identical to part of the surface of the sub-volume with part of the surface of the object. The thickness of the sub-volume according to the preceding embodiment is measured from this common surface to the center of the object. A thickness range of 0.5 µm to 500 µm in this context is provided, for example, when the object is a film, a tape, an adhesive layer, etc. A thickness of 0.5 mm to 5 mm can be provided in particular when the object is a housing, a panel, an insert, a container, a carrier, a product, a good, etc.

[0019] In one embodiment, the subvolume can be transparent, translucent, or colored with a dye. In this context, the term "transparency" refers to a surface that is smooth and has a low surface roughness (e.g., PPMA or PC, crystal-clear). "Translucent" means milky scattering, either through integrated scattering particles or through the surface roughness (e.g., frosted glass). "Colored" in this context means that a dye, such as a glass with chemical additives, is added to the subvolume.

[0020] In a further embodiment, it can be provided that the object further comprises markings that are arranged relative to the sub-volume. With regard to the markings, it can be provided that the markings are applied to the object by printing and / or surface contour elevations or depressions. This serves to adjust a detection device for particle detection, i.e., to determine the relative arrangement of the fluorescent marker particles arranged in the sub-volume. The marking can in particular comprise at least one reference point that allows the object to be positioned such that the emission, and thus the position, of the fluorescent marker particles can be determined with the aid of a suitable detection device.

[0021] In a further embodiment, the volume ratio of the average particle volume to the sub-volume can be at least 1:20. In this context, "at least" means that the volume ratio can shift in favor of the sub-volume (e.g., 1:25, 1:30, etc.). The following conceptual model serves as an example for determining the volume ratio: A "particle," ideally consisting of 9 (3 × 3 stacked) imaginary stone cubes, is integrated centrally into a volume of 7 × 7 × 3 imaginary glass cubes. The arrangement is designed for 1-to-1 pixel cube identification with a camera that captures the 9 particle cubes and the two surrounding rows of glass cubes perpendicular to the 7x7 glass cube surface. This model results in a minimum volume ratio of approximately 9:147 = 1:17.The usual volume ratios can be reduced to ten to single-digit ppm values, so that statistically only one particle is present in the subvolume. In practice, of course, a statistically meaningful ratio in between is set. The actual goal of the ratio is to sufficiently separate the particles for later identification and to avoid particle overlap. When varying the ratio, it is also to achieve the greatest possible distinguishable particle arrangement probability, from which the range of variants of the FMCC (Fluorescent Marker Characterization Code) is then derived.

[0022] According to one embodiment, it can be provided that the outer contour of the sub-volume is quadrangular, square, round or three-dimensionally free-form.

[0023] In a further embodiment, it can be provided that the product and the casing are connected to each other.

[0024] According to a further embodiment, it can be provided that the sheath cannot be separated from the goods without causing damage.

[0025] In a further embodiment, the casing can be detachable from the product. In such an embodiment, the article is, for example, a package, a container, a carrier, a box, etc.

[0026] According to a further embodiment, the wrapping may only partially enclose the product. In such an embodiment, the object is, for example, a packaging tape, a panel, an insert, etc.

[0027] In a further embodiment, both the cladding and the subvolume can be transparent. In this context, transparent means that the optical refractive index of the materials is preferably the same or does not differ by more than ± 15%.

[0028] The object is further achieved by a method for identifying an object, comprising the steps: a) providing an object according to the invention; b) determining the random spatial distribution of the fluorescent marker particles in the subvolume; and c) comparing the determined random spatial distribution with stored information on the random spatial arrangement to identify the object.

[0029] According to one embodiment, it can be provided that determining the random spatial distribution of the fluorescent marker particles in the subvolume comprises the opto-sensory detection of an emission of the fluorescent marker particles.

[0030] In a further embodiment, it can be provided that the matching in step c) comprises converting the determined random spatial distribution of the fluorescent marker particles into a mathematical code characteristic of the distribution.

[0031] According to a further embodiment, in addition to the random spatial distribution, the size and / or shape and / or chemical composition of the fluorescent marker particles can be determined, and the information thus obtained can be compared with corresponding stored information. In this context, it is provided that the chemical composition correlates with the fluorescence emission.

[0032] In a further embodiment, the determination in step b) may include the evaluation of at least one emission line. The emission lines can be individual spectral colors or emission wavelength ranges. For example, the markers preferably emit at approximately 470 nm, 550 nm, 670 nm (VIS), and 800 nm (NIR), each + / - 20 nm.

[0033] In a further embodiment, it can be provided that, in addition to the random spatial distribution, an emission decay time of individual particles is determined after deactivation by excitation.

[0034] In a further embodiment, it can be provided that an emission decay time of individual particles is determined for the random spatial distribution upon activation of the excitation.

[0035] In a further embodiment, it can be provided that, in addition to the random spatial distribution, an emission intensity of individual particles is determined upon activation of an excitation.

[0036] According to a further embodiment, the determination in step b) can be carried out using a camera, a line-scan camera, or a smartphone camera. The particle positions, in particular the position depth transverse to the identification surface, can be recorded using known methods: for example, using a stereo lens, a stereo camera, using depth of field, using triangulation methods, by moving the camera longitudinally or at an angle to the identification window, or using a time-of-flight (ToF) camera. The smartphone camera can also be an attachment (particularly with regard to particle excitation) for the smartphone camera.

[0037] Finally, according to one embodiment, it can be provided that the comparison in step c) comprises the comparison with a mathematical characterization code of the fluorescent marker particles, which is stored in a storage database or cloud.

[0038] The object marked according to the invention and the identification thereof by means of the method according to the invention make it possible to overcome disadvantages of the prior art and in particular to achieve the following technical advantages. a) Integration of the fluorescent marker particles (FMP) is possible within the framework of already required standard production processes, so that no additional production step or component is required to apply the identification means; b) Invisible integration of the identification feature is possible without influencing the surface or design of the object, goods, or product, due to the small particle size and the low white-diffused daylight emission characteristics; c) An exorbitant number of coding options and codes is possible for extensive product ranges and high volumes of products: through the position of the particles, through the variation of the particle sizes, through different particle color emissions, through different particle geometries. The only limitations are the window size and the camera resolution.d) Identification feature with maximum copy protection and therefore maximum protection against counterfeiting, since, in contrast to printed barcodes, QR codes and the like, it is practically impossible to copy the random two- and three-dimensional position as well as the properties of the fluorescent marker particles; e) Identification feature with additional protection against counterfeiting, since the feature (e.g. the position of the pattern) and the identification method (e.g. which characteristic orInformation of the particles is evaluated, how the mathematical model is constructed) is unknown to the counterfeiter; f) Identification feature in which the identification window (= sub-volume) can be visible to make it easy to locate the detection area with the detection device; g) Identification feature in which the identification window (= sub-volume) can be invisible and can be varied to make copying or counterfeiting significantly more difficult; h) Particularly high-contrast particle pattern and therefore identification feature, since when using "up-conversion" FMP and excitation in the NIR, no other optical signals are generated in the VIS other than the up-conversion fluorescence of the FMP and all production materials, both synthetic and natural, show no or no relevant up-conversion fluorescence.Any Stokes fluorescence is therefore far inferior in terms of particle pattern contrast compared to the patented use of up-conversion FMP. i) In addition, the use of up-conversion FMP, due to the high contrast of the particle pattern, allows the particle patterns to be measured and detected even on damaged or scratched detection area surfaces. j) Furthermore, the particle size can be adapted to the product or object size. The same applies to the subvolume.

[0039] As a result, the method according to the invention provides the following general advantages: a) Simple and cost-effective identification marking for objects, goods or products b) Clear and unique identification technology c) Quick and easy to read d) Cost-effective control and evaluation technology DETAILED DESCRIPTION OF THE INVENTION

[0040] In the following, the invention will be described with reference to specific embodiments and the drawings, without necessarily considering the features mentioned in this context as essential to the invention. Rather, individual features can be combined with the general features mentioned above. The following description serves in particular to explain the invention with reference to specific embodiments. Fig. 1: Schematic spatial representation of an article according to the invention comprising fluorescent marker particles Fig. 2: Schematic representation of a device for carrying out the method according to the invention for identifying the Fig. 1 shown object; Fig. 3: Flowchart for the schematic sequence of the method according to the invention in a preferred embodiment.

[0041] Fluorescence is a common technology for shifting the wavelength of an emission source from the edge of the visible spectrum, or even outside of this range, into the "visual zone" (approximately 380 nm–780 nm) within the so-called luminosity curve V(λ). Using suitable fluorescent pigments, both Stokes shifts can be achieved, in which the re-emitted emission wavelength is emitted in a stretched manner relative to the excitation wavelength using a "downshift," and the anti-Stokes shift, in which the emission wavelength is emitted in a compressed manner using "upconversion."

[0042] For the present invention, both approaches are conceivable: i.e., excitation of "down-shift" FMP (fluorescent marker particles) with a UV LED or a UV laser, or excitation of "up-converting" FMP with an IR light-emitting diode or an infrared laser. Up-converting is preferred here because this effect can be better detected due to its "unnaturalness" (emitting higher-energy wavelengths relative to the excitation wavelength). In addition, a completely invisible detection method can be implemented by using suitable FMP that are both excited in the near-infrared spectral range (NIR) and emit in the NIR range (e.g., excitation at approximately 980 nm and emission at 800 nm). By appropriately doping the fluorescent material, any emission color (in the visible spectral range VIS) can be generated.When excited at 980nm, particles with individual or different emission ranges, for example with the peak wavelength of 480nm, 546nm, 607nm and 758nm, can be distinguished.

[0043] Using a commercially available camera, it is possible to detect these emissions without any special effort in both the VIS and NIR ranges. Further information on FMPs can be obtained from general publications, including WO 2017 / 220079 A1 and DE 10 2014 105 846 A1.

[0044] After wet and dry chemical synthesis, FM particles typically range in size from slightly less than 1 µm to particles and particle agglomerates up to several hundred micrometers. Grinding and sieving can be used to separate the required particle sizes.

[0045] The selected particles can then be used to fill the product, object, or goods casing using commercially available and well-known processes, for example, by FMP compounding of the casing material using an extruder or by multilayer stacking of films with FMP-filled adhesive layers, or by 3D printing with FMP-filled filaments. The casing is transparent or translucent (opaque or milky transparent) across the UV, visible (VIS), and near-infrared (NIR) spectral range to enable both FMP excitation and optosensory evaluation. The casing can be a film (provided the material thickness is greater than the particle size), preferably a blister pack. A transparent housing, box, or other container is also conceivable.

[0046] A corresponding embodiment is described in the Fig. 1 shown. In this embodiment, the object 100 comprises a casing 110 and a product 120. The product 120 is completely enclosed by the casing 110. In the embodiment shown, the object 100, or more precisely the casing 120, comprises a subvolume 130, which represents a portion of the volume of the casing 120 and thus of the object 100. Fluorescent marker particles (not shown) are distributed in a random arrangement within the object 100. At least some of the particles are present in a random arrangement within the subvolume 130.

[0047] The described sheathing can be firmly and non-destructively detachably connected to the product, e.g. by bonding, a 2K injection molding process or lamination or a 3D printing process. A related example is given in Fig. 1b shown.

[0048] Furthermore, the wrapping can completely or partially enclose the goods, e.g., a strapping band for securing goods on a pallet. Finally, it is also conceivable for the wrapping to be limited almost entirely to the sub-volume.

[0049] The sub-volume can have the following properties: It is characterized by the fact that a spatial evaluation of the randomly arranged fluorescent marker particles in the volume only takes place in this surface casing area and that the area, or the volume behind it, is either visible or invisibly, i.e. not highlighted. A visible shape could be, for example, a frame print or a targeted casing surface change in the detection area, e.g. a groove, a bump or depression, or a coloring of the volume-shaped window itself. With the 'invisible' shape, the sub-volume cannot be distinguished from the surrounding casing area. The actual sub-volume is only delimited by the positioning of the detection device and is therefore 'known' only to the person detecting or the detection device.Existing edges, contours, positioning aids and / or, in addition to these mechanical elements, optical properties of the object close to or distant from the subvolume can serve as a reference for positioning alignment.

[0050] In the Figur 2 An apparatus for carrying out the method according to the invention is shown. An object 200 is to be identified, comprising a casing 210 and a product 220, wherein, according to the Fig. 1 , in a sub-volume 230 and possibly in the remaining volume of the object 200 fluorescent marker particles 240 / 245 are present in random arrangement. Fig. 2 The object 200 shown further comprises markings 250 in the form of notches, which make it possible to arrange the object 200 such that the fluorescent marker particles 240 contained in the subvolume 230 can be detected by the detection device 260. The detection device 260 serves to determine the random spatial distribution of the fluorescent marker particles 240 in the subvolume 230 and includes an excitation source 270, a camera 280, and a control and evaluation unit 290. After determining the random spatial distribution of the fluorescent marker particles 240 in the subvolume 230, the evaluation unit 290 is used to generate the mathematical FMCC 295 for comparison with stored data in order to identify the object 200.

[0051] In a special embodiment, this method can be carried out as follows. First, the detection device is aligned with the casing over the sub-volume using positioning springs. The sub-volume can be designed to be visible or invisible. The aperture of the detection device keeps out unintentional extraneous light. In the sub-volume, EMPs (emission particles) are irradiated by the excitation source in the detection device and evaluated by a camera (each controlled by the control and evaluation unit). The camera, which can be a matrix-based CCD, CMOS, ToF, dual, or line scan camera, records the three-dimensional position of the FM particles using known methods such as depth of field variation, triangulatory measurement, e.g., with a transversely varying camera or using a dual camera. In addition, the camera detects the emission color (orthe emission color range) of the particles, the size, the contour, and the spatial position or orientation in space.

[0052] The control and evaluation system records the measured data and converts it into a unique Fluorescence Marker Characterization Code (FMCC) using a mathematical algorithm that will not be explained further here. The FMCC is intended to fully describe the particle constellation and, at the same time, to be error-tolerant to mechanical influences, such as wear on the coating surface, thanks to the richness of variation and cubic data enabled by the method.

[0053] A complete possible measurement sequence of the method is shown in Fig. 3described. As already explained, the first step is to align the detection unit. Then the subvolume is referenced. Either using image processing, optically detectable markings, or mechanical reference points. When using image processing for optical detection, it is advisable to additionally use illumination in the visible radiation spectrum (which was not explicitly shown in sketch 2). After exciting the EMP with infrared and / or ultraviolet light, the spatial EMP positions are localized, the particle spectral color is detected, the EMP size and geometry are measured, and the EMP position in space is recorded. Optionally, it is possible to also evaluate the photometric rise behavior of the EMP when the excitation source is switched on. The photometric decay behavior can also be recorded after the excitation source is deactivated.These temporally exponential luminous properties of the fluorescent marker particles during and after excitation can be specifically adjusted by appropriate doping of the EMP and can also be included in the calculation of the FMCC.

[0054] Finally, with the help of the FMCC, product allocation, tracking, data processing and storage can be carried out using conventional technologies.

Claims

1. A method of identifying an article comprising the steps of: a) providing an article comprising fluorescent marker particles, wherein - the fluorescent marker particles are distributed in the entire volume of the article or in a portion of the volume of the article and the fluorescent marker particles are present in this entire volume or in said portion of the volume in a random distribution; - the volume in which the fluorescent marker particles are distributed comprises a sub-volume; - the sub-volume contains at least a portion of the fluorescent marker particles; - the sub-volume is at least partially transmissive to electromagnetic radiation having a wavelength in the visible range and / or in the near infrared range and / or in the UVA range; and - a portion of the surface of the sub-volume is identical to a portion of the surface of the article; b) positioning a detection device by means of optical properties of the article and / or by means of mechanical elements of the article and / or by means of positioning aids so that the fluorescent marker particles can be detected in the sub-volume by means of the detection device; c) determining the random spatial distribution of the fluorescent marker particles in the sub-volume by means of the detection device; and d) matching the determined random spatial distribution with stored information about the random spatial arrangement for identifying the article.

2. The method of identifying an article according to claim 1, wherein the fluorescent marker particles comprise at least two different types of fluorescent marker particles which differ from each other in their size and / or shape and / or chemical composition.

3. The method of identifying an article according to claim 1 or 2, wherein the article comprises a good and / or a covering, wherein the covering at least partially encloses the good.

4. The method of identifying an article according to any one of the preceding claims, wherein the fluorescent marker particles are suited to emit at least two different emission lines in the visible range and / or in the near infrared range upon excitation with an infrared source.

5. The method of identifying an article according to any one of the preceding claims, wherein the sub-volume is optically indistinguishable from at least a portion of the remaining article.

6. The method of identifying an article according to any one of the preceding claims, wherein the sub-volume is transparent, translucent or dyed with a dye.

7. The method of identifying an article according to any one of claims 3 to 6, wherein both the covering and the sub-volume are transparent.

8. The method of identifying an article according to any one of the preceding claims, wherein determining the random spatial distribution of the fluorescent marker particles in the sub-volume comprises opto-sensory detection of an emission of the fluorescent marker particles.

9. The method of identifying an article according to any one of the preceding claims, wherein the matching in step c) comprises converting the determined random spatial distribution of the fluorescent marker particles into a mathematical code.