PRODUCT HAVING AN OPTOELECTRONICALLY READABLE CODE

Description

[0001] The invention relates to a method for producing a product surface comprising an optoelectronically readable code which is formed by an arrangement of flat cells of different cell types.

[0002] Using an optoelectronically readable code, information can be easily displayed on a product. Examples of this are a product number represented by a barcode or an internet address represented by a QR code (Uniform Resource Locator), which for example refers to a website of the product manufacturer. The cell types of such codes must differ sufficiently in their optical contrast so that the cells can be detected and differentiated by an optoelectronic reader. Typically, a code has two cell types that differ in their color, for example in their hue and / or color saturation and / or brightness value. This results in an optical contrast in brightness orThe intensity of the light reflected by the cells of different cell types, which can be detected by an optoelectronic reader and used to differentiate between cell types. Due to the high optical contrast, a combination of black and white cells is a common representation. Such codes are typically applied to the product surface during or after production in the form of an additional colored layer.

[0003] A "code" is understood here as the representation of data in symbols. A "cell" is a flat area that represents such a symbol through its optical appearance and / or geometric shape and / or together with other cells. Two cells of the same cell type have a similar optical appearance and / or geometric shape. Two cells of different cell types differ significantly in their optical appearance and / or geometric shape. An "optoelectronically readable" code can be read by an optoelectronic reader and decoded and interpreted using appropriate software.

[0004] CA 2311960 C discloses a pneumatic vehicle tire and a method for its production, which has a vulcanized ink coating on the surface of the tire sidewall with a barcode. During the production of the pneumatic vehicle tire, the vulcanized ink coating is applied to the surface of the unvulcanized pneumatic vehicle tire and vulcanized together with it.

[0005] The use of a layer made of materials and / or colors other than the material and / or color of the product surface on the product surface can have a negative impact on the viewer's overall impression of the product. In addition, the readability of such a code is limited, for example, by the stress the other materials and / or colors are subjected to during manufacture and / or use of the product. This can occur due to stretching or exposure to heat during manufacture, discoloration due to sunlight, or detachment of the layer due to mechanical stress during use of the product. Particularly in large production runs, it is time-consuming and expensive to provide each individual product with an additional layer. Therefore, efforts are being made to find a simple and cost-effective way to apply the code to the product surface.

[0006] US 4625101 A discloses a tire sidewall having an optoelectronically readable one-dimensional code that is an integral part of the tire sidewall. US 4644151 A discloses an optoelectronically readable code that is an integral part of the outer surface of a glass bottle. US 2006 / 151451 A1 discloses a method for applying a marking to a tire by laser engraving the vulcanized sidewall of the tire.

[0007] The object of the invention is to provide a product surface having a code that is optoelectronically readable, whose readability is robust against stress during manufacture and / or use of the product surface, and which is cost-effective. Furthermore, the object of the invention is to provide a method by which such a product surface can be produced in a simple manner.

[0008] The object relating to the method for producing a product surface is achieved according to the invention by claim 1.

[0009] The product surface has an optoelectronically readable code which is formed by an arrangement of flat cells of different cell types, wherein the cells are an integral part of the product surface, wherein the cells of each cell type each have a surface profile, wherein the surface profile of at least one cell type has at least one elevation and / or depression relative to the product surface, wherein the surface profile of a first cell type is designed relative to the surface profile of a second cell type such that the reflection properties of the surface profile of the first cell type differ from the reflection properties of the surface profile of the second cell type, wherein the code is a two-dimensional code, in particular a quick-response (QR) code, wherein the product surface is made of a polymeric material, in particular of an elastomeric material,and wherein the product surface is the surface of a sidewall of a pneumatic vehicle tire.,

[0010] It is important to note that the cell types differ in the intensity of the light reflected by the surface profiles of the cells of the two cell types due to the different reflection properties of their surface profiles when exposed to light.

[0011] The difference in intensity is therefore not caused by the different colors and / or materials of the cell surfaces of different cell types, but by the different designs of the surface profiles of the cell types. The surface profile of the cells of at least one cell type has elevations and / or depressions relative to the product surface, which influence the reflection properties. The surface profiles of the cell types are designed in such a way that the surface profile of one cell type differs in its reflection properties from the reflection properties of the surface profiles of the other cell types. The light reflected by the cells of different cell types therefore has different intensities. The resulting difference in intensity can be detected by an optoelectronic reader.This allows cells of different cell types to be distinguished and the code can be read using an optoelectronic reader.

[0012] The "surface profile" of a cell type or the "surface profile" of the cells of a cell type characterizes the elevation(s) and / or depression(s) on the surface of the cells of the cell type. The surface profile includes the density and / or height of the elevations and / or depressions on the surface and / or the orientation of the surface or parts of the surface.

[0013] The "reflection properties" characterize how light striking a surface is reflected. The reflection properties are influenced by the surface profile and the surface material. The reflection properties are influenced by effects known to the expert, such as absorption and / or reflection and / or shading. Reflection occurs diffusely and / or specularly. The intensity of the reflected light depends on the direction.

[0014] Surface profiles that differ in their reflective properties differ in the characteristic features of the light they reflect. The light reflected by cells of one cell type is therefore not necessarily identical in all characteristics, but rather exhibits the same characteristic features—i.e., the same reflective properties, which differ from the reflective properties of cells of another cell type. Accordingly, the elevations and / or depressions of different cells of a cell type are characterized by the surface profile, but are not necessarily identical.

[0015] As the expert knows, the light reflected from a surface also depends on the direction, intensity, and wavelength of the incident light. The invention assumes a sufficient light source. This could be, for example, an active light source integrated into the optical reader or ambient light such as sunlight or room lighting.

[0016] The "optoelectronic reader" comprises at least one light detector. An optoelectronic reader can be a reader such as a barcode scanner that actively emits light and detects the light reflected back into the detector. It can also be an optoelectronic reader such as a smartphone equipped with photo optics and suitable software that detects light reflected from the environment by the surface of the code into the detector. The optoelectronic reader detects the intensity of the light reflected by the individual cells with a spatial resolution of at least the minimum cell dimension and is sensitive to the difference in intensity of the light reflected by cells of different cell types. The cells are thus detected and differentiated, allowing the code to be read optoelectronically.Interpretation software, either external or integrated into the optoelectronic reader, decodes and interprets the information presented by the code. The detection mechanism and interpretation software can be tailored to the requirements of the code integrated into the product surface.

[0017] "Light" refers to electromagnetic radiation suitable for detection by an optoelectronic reader. In particular, this refers to electromagnetic radiation with a wavelength of 380 nm to 780 nm.

[0018] The cells of the code are an integral part of the product surface, i.e., they are formed as a three-dimensional profile from the material of the product surface or the product itself. The material of the product surface is tailored to the stresses and strains encountered during manufacture and / or use of the product. For example, the elastomer material of the surface of a pneumatic vehicle tire is designed to withstand the heavy loads caused by high temperatures during vulcanization. Thus, no general loss of code readability is to be expected due to stresses and strains encountered during manufacture and / or use of the product surface. The readability of the code is robust against these stresses and strains, and no additional complex and costly measures are required to protect the readability of the code.

[0019] A further advantage of the code cells integrated into the polymer surface and the creation of the intensity difference through different surface profiles is that the complex and costly application of one or more additional layers of color and / or other materials to the product surface is eliminated. Furthermore, the viewer's overall impression of the product is not influenced by the color and / or other materials on the product surface.

[0020] It is advantageous that the code is a two-dimensional code.

[0021] It is also advantageous for the product surface to be formed from a polymeric material, in particular an elastomeric material. Polymeric material, in particular elastomeric material, is ideally suited for a product surface according to the invention.

[0022] Another advantage is that the product surface is the sidewall surface of a pneumatic vehicle tire. The sidewall is subjected to considerable stress during production and use. During production, the elastomeric material is exposed to high temperatures in the vulcanization process. In use, for example, a pneumatic vehicle tire is exposed to severe weather fluctuations. The elastomeric material is designed to withstand these stresses. The readability of a code that is made of this elastomeric material itself as an integral part of the product surface is robust against these stresses.

[0023] The use of the product surface, particularly for the sidewall of a pneumatic vehicle tire, makes it possible to display statutory product information and / or optional information, in particular an internet address, using the code integrated into the product surface. This creates a compact representation of this information that can be read using an optoelectronic reader. The internet address can refer to a website containing further information, in particular information about the product and / or the manufacturer and / or installation and / or user instructions.

[0024] Similar advantages arise when using the product surface on a conveyor belt, e.g. at a location that is not permanently exposed to bulk material.

[0025] Thus, a cost-effective product surface is provided which has an optoelectronically readable code whose readability is robust against stress during manufacture and / or use of the product surface.

[0026] It is advantageous if the code is composed of cells of two cell types. Such a code is ideal for representing binary-coded information.

[0027] It is advantageous if the surface profile of the first cell type absorbs light more strongly than the surface profile of a second cell type. The two cells have the same dimensions. It has been shown that cells of two such cell types can be easily distinguished using a suitable optoelectronic reader.

[0028] It is also advantageous if the surface profile of a first cell type reflects less light into a detection solid angle of 0.0955 sr (steradian) relative to the surface profile of a second cell type. The two cells have the same dimensions. 0.0955 sr corresponds approximately to a solid angle spanned by a right circular cone with an aperture angle of 20°. The detector of the optoelectronic reader can be easily positioned within such a solid angle. This optimally ensures reliable and easy detection of the code by an optoelectronic reader.

[0029] Particularly suitable in this case are two cell types with surface profiles that have different levels of absorption and / or with surface profiles in which the surface profile of the first cell type preferably reflects diffusely and the surface profile of the second cell type preferably reflects into the detection solid angle and / or with surface profiles in which the surface profile of the second cell type preferably reflects into the detection solid angle and the surface profile of the first cell type preferably reflects into a solid angle different therefrom.

[0030] Preferably, the detection solid angle is within the working angle. The working angle is the solid angle spanned by a circular cone positioned perpendicular to the product surface with an aperture angle of 120°. The detector of the electro-optical reader is typically positioned within the working angle, so that a detection solid angle within the working angle ensures reliable reading of the code. It is advantageous if every detection solid angle within the working angle fulfills the above condition.

[0031] It is advantageous if the surface profile of a cell type has elements that form a structure and / or texture. The height of the elements can be regular or irregular. The term "structure" encompasses the regular arrangement of elements, such as regular hatching, i.e., straight and parallel bars, such as regular grids of elements or lattice structures of intersecting bars. The term "texture" encompasses an irregular but largely homogeneous distribution of elements, in particular a distribution of height and / or arrangement of the elements according to a statistical distribution or noise. Such a surface profile enables a targeted influence on the characteristic reflection properties. Through the targeted selection, arrangement, and dimensioning of the elements of the structure and / or texture, a predominantly directed or predominantly diffuse reflection can be achieved.By repeatedly reflecting the light from multiple elements, the absorption coefficient is increased. By deliberately combining cell types with surface profiles exhibiting a different structure and / or texture, the difference in reflected intensity between the cell types can be specifically increased, thus optimizing the optoelectronic readability of a code. A similar effect is achieved by combining cell types in which a first cell type has a surface profile with a structure and / or texture and a second cell type has a surface profile without a structure or texture.

[0032] Elements based on the shape of a ridge and / or a cylinder and / or a pyramid and / or a cone and / or a truncated pyramid and / or a truncated cone have proven advantageous for specifically influencing reflection properties. For example, the preferred directions of reflection can be specifically influenced by aligning the longitudinal extent of ridges. Cylindrical, pyramidal, or conical elements are ideal for increasing the absorption coefficient by repeatedly reflecting light from multiple elements. By combining a first cell type with such a surface profile with a second cell type with a surface profile that has a lower absorption coefficient, a significant difference in intensity between the cell types can be achieved. Such a code is optoelectronically readable.A surface profile with a maximum roughness depth of 0.01 mm is suitable as a surface profile with a lower absorption level.

[0033] It is advantageous if the surface of the elements has elevations and / or depressions, particularly a stepped structure. Such a structure increases the degree of absorption and / or diffusion.

[0034] It is advantageous if the element tips of two adjacent elements are spaced between 0.01 mm and 0.8 mm, particularly preferably between 0.06 mm and 0.3 mm. Such a spacing is ideal for manipulating the reflective properties of light without the individual element standing out to an observer on the product surface.

[0035] Corresponding advantages arise when elements of a surface profile of a cell type have a height difference of 0.08 mm to 0.5 mm, particularly preferably a height difference of 0.15 mm to 0.3 mm. Preferably, all elements have such a height difference. The height difference of an element is measured as the difference in height between the element base and the element tip.

[0036] It is also advantageous if the surface profile of a cell type has areas with a maximum roughness of 0.01 mm, preferably a maximum roughness of 0.008 mm. Such an area exhibits a high reflection rate for light and / or characteristic reflection properties. In particular, such a surface profile exhibits a high degree of reflection. Furthermore, such a roughness corresponds to the typical production-related roughness of many product surfaces.

[0037] According to DIN EN ISO 4287:1998, the "roughness depth" is the arithmetic mean of the individual roughness depths of consecutive individual measurement sections. The individual roughness depth is the maximum height difference within an individual measurement section. If the surface profile consists largely of elements, the roughness depth is the maximum of the roughness depth according to DIN EN ISO 4287:1998 and the mean height difference of the elements.

[0038] Furthermore, it is advantageous if the surface profile of a cell type corresponds to the surface profile of the product surface. The surface profile of the product surface with the lowest roughness depth is particularly suitable. Therefore, additional processing or deformation of the product surface and / or a tool for processing or deformation of the product surface is not necessary for cells of this cell type.

[0039] It is advantageous if the surface profiles of the cell types of a code differ in their roughness depth, in particular if the ratio of the roughness depth of the surface profile of a first cell type to the roughness depth of the surface profile of a second cell type is at least 20, in particular at least 30. The reflection properties of such surface profiles differ sufficiently to provide a code readable by an optoelectronic reader.

[0040] It is useful for cells to have an additional height profile. This can be an inclination and / or curvature of the cell surface and / or a depression or elevation of the cell surface relative to the product surface. The reflection properties of all cell surfaces of a cell type can be influenced by an inclination and / or curvature. An inclination and / or curvature of cell surfaces can also compensate for an inclination and / or curvature of the product surface, so that the readability of the code is increased by cell surfaces that are largely parallel to one another. A depression of cell surfaces, especially when the maximum height of the surface profiles corresponds to or is lower than the level of the product surface, serves to protect against mechanical stress, such as scratching. A depression or elevation of cell surfaces can also increase the readability of the code due to the resulting shading.

[0041] It is expedient if the code is a one-dimensional code, in particular a barcode, or a two-dimensional code, in particular a quick response (QR) code. Any code type that can be represented by cells of at least two cell types in one area is suitable. In a preferred embodiment, a cell is represented by a circle, a circular disk, a line, a rectangle, or a square. Two-dimensional codes that are particularly suitable include stacked codes such as the Codablock, Code 49, and PDF417, as well as matrix codes such as QR codes, the DataMatrix Code, MaxiCode, and Aztec Code, as well as dot codes. QR codes also include further developments such as the Design QR Code, Micro QR Code, Secure QR Code, and iQR Code.

[0042] It is advantageous if the code covers a surface area of ​​1 cm² to 16 cm² on the product surface. However, the invention is also suitable for codes with a larger or smaller surface area.

[0043] According to the invention, the method for producing such a product surface consists in using a mold to produce the product and in the code being embossed into the product surface during product manufacture by an appropriately designed molding surface of the mold. The mold can be a roller that embosses the code into a surface that has not yet hardened. The manufacturing method can also be a shaping process in which the raw material or the precursor is placed in a mold and takes on a product shape determined by this mold. Shaping processes include casting processes, injection molding processes or vulcanization processes using a vulcanization mold. The code is introduced into the mold as a negative mold and is embossed directly into the product surface during the shaping production step.No complex additional work step is required to apply the code, such as applying an additional layer of material and / or ink to each individual product. This allows a product with an optoelectronically readable code on its surface to be manufactured more cost-effectively and easily.

[0044] According to the invention, the mold for producing the product is provided with a recess into which a replaceable stamp complementary to the recess can be exchangeably arranged. The replaceable stamp has a forming surface through which the code can be transferred to the product surface. By exchanging the replaceable stamp, product surfaces can be easily provided that differ in their embossed code. The forming surface of the replaceable stamp is preferably made of steel or silicone or coated with such a material. With such an replaceable stamp, very fine structures can be embossed into the product.

[0045] Further features, advantages, and details of the invention will now be described in more detail with reference to the figures, which illustrate schematic embodiments. The following shows: Fig. 1 the reflection of light from a product surface; Fig. 2a top view of a product surface having a QR code, Fig. 3 a top view of a cell of a code, Fig. 4 a cross-section through two adjacent cells of different cell types, Fig. 5 a section of the surface of an element, Fig. 6 to 9 a grayscale representation of the surface profile of a cell in plan view.

[0046] The Figure 1illustrates the reflection of light on a product surface 1, which is shown in cross-section. Incident light 2 strikes the product surface 1. According to the reflection properties of the surface profile 3 of the product surface 1 (not shown in detail), a portion of the light 41 is absorbed by the product surface 1, while another portion of the light 4 is thrown back, i.e. reflected. The intensity of the reflected light 4 is direction-dependent and is influenced by the surface profile 3. The direction and intensity of the incident light 2, the absorbed light 41, and the reflected light 4 are illustrated by the direction and length of the arrows. A portion of the reflected light 4 reaches a detector 16 of an optoelectronic reader, which detects the intensity of the light with spatial resolution.

[0047] The Figure 2shows a section of a plan view of a product surface 1 having a code 5, which is a QR code. The code 5 has cells 6 of a first cell type and cells 7 of a second cell type, which are an integral part of the product surface 1. The cells 6 of the first cell type have a surface profile 3 with depressions relative to the product surface 1. The surface profile 3 of the cells 6 differs in its reflection properties from the surface profile 3 of the cells 7 of the second cell type. The code 5 is square with an edge length 11 of 2 cm and thus occupies an area of ​​4 cm2 on the product surface 1. The cells 6, 7 are square with an edge length 12 of approximately 0.69 mm.

[0048] The product surface 1 is preferably the surface of a sidewall of a pneumatic vehicle tire.

[0049] The Figure 3shows a plan view of a cell 6 of a first cell type of a code 5, for example the cell 6 of the Figure 2 shown QR codes 5. In conjunction with the Figure 4 It can be seen that the surface profile 3 of cell 6 has elements 8 that form a structure. The structure is a hatching with regularly arranged webs with a triangular cross-section as elements 8. The distance 13 between the element bases 9 and the element tips 10 is 0.24 mm.

[0050] The Figure 4 shows a cross section along the line AA through the Figure 3 represented cell 6 of the first cell type and by an adjacent cell 7 of a second cell type of code 5, for example by an adjacent cell 7 of the second in Figure 2shown cell type. The surface profile 3 of cell 6 has a surface roughness of 0.2 mm with a height difference 14 of 0.2 mm between the element bases 9 and the element tips 10. The surface of cell 6 is lowered relative to the product surface 1 by an additional height profile such that the element tips 10 are 0.05 mm below the level of the product surface 1. The surface profile 3 of cell 7 of the second cell type has a surface roughness of 0.008 mm according to DIN EN ISO 4287:1998. The surface roughness of the surface profile 3 of cell 6 of the first cell type is thus a factor of 25 greater than the surface roughness of the surface profile 3 of cell 7 of the second cell type.

[0051] A section 15 of element 8 from Figure 4 is in Figure 5 The surface of element 8 has a stepped structure with a step height of 0.02 mm.

[0052] The reflection properties of the Figures 3 to 5The surface profile 3 of cell 6 shown in Figure 1 differs significantly from the reflection properties of the Figure 4 The surface profile of cell 7 shown in the figure. The surface profile of cell 6 is designed to absorb more light than the surface profile of cell 7. The surface profile of cell 7 reflects more light into a solid angle of 0.0955 sr within the working angle. Cells 6, 7 can be detected and differentiated with an optoelectronic reader. A code comprising two such cell types is thus readable by an optoelectronic reader.

[0053] The Figures 6 to 9 each show a plan view of further embodiments of a cell 6. The surface profile 3 of each cell 6 is shown as a grayscale image. The surface profiles 3 of the cells 6 have a higher absorption than the Figure 4shown surface profile 3 of cell 7 and reflect less light into a solid angle of 0.0955 sr within the working angle than the surface profile 3 of the cell 7 shown in Figure 4 shown cell 7. A code that identifies a first cell type with one of the Figures 6 to 9 shown surface profiles 3 and a second cell type with the Figure 4 shown surface profile 3 of the cell 7 can be read by an optoelectronic reader. A comparison of these combinations has shown that a code whose first cell type is the one shown in Figure 7 shown surface profile 3 and its second cell type the surface profile of the in Fig. 4 shown cell 7, leads to the best detection result.

[0054] The height of the elevations and / or depressions of the surface profile 3 are represented in the grayscale image by 256 gray levels. Black represents the lowest point, white the highest point of the surface profile 3. The height difference is 0.2 mm. Due to the discrete height gradations according to the discrete grayscale values, the elements 8 of the surface profiles 3 have a stepped structure. Such a surface profile 3 or the complementary surface profile of a mold for producing such a surface profile 3 on a product surface 1 can be produced, for example, by laser engraving. Figure 6 , 7 and 9 the edge length of each pixel is 20 0.02 mm, in Figure 8 the edge length of each pixel is 20 0.04 mm.

[0055] Each pixel 20 thus has a constant height, which is represented by the gray level. The gray level of each pixel 20 is represented by the cumulative area of ​​the black fields 25 within the pixel 20. The fields 25 are, in particular, rectangles. For example, it is clearly visible that pixel 21 has a significantly smaller cumulative area of ​​the fields 25 than pixel 22. Pixel 21 is therefore assigned a lower (lighter) gray level than pixel 22. Pixel 21 therefore has a greater height in the surface profile 3 than pixel 22. Furthermore, in the Figures 6 to 9 Pixel 23 has a significantly larger cumulative area of ​​the fields 25 than pixel 22. Pixel 23 is therefore assigned a higher (darker) gray level than pixel 22.

[0056] Thus, pixel 23 has a lower height in surface profile 3 than pixel 22. Pixel 20 with the smallest cumulative area of ​​fields 25 is assigned the gray level white, and pixel 20 with the largest cumulative area of ​​fields 25 is assigned the gray level black.

[0057] The Figure 6 The surface profile 3 shown as a grayscale image has a structure whose elements 8 are arranged in a rectangular grid.

[0058] The Figure 7 The surface profile 3 shown as a grayscale image has a structure with offset elements 8.

[0059] The Figure 8 Surface profile 3, represented as a grayscale image, has a texture, with the height of the pixels 20 being statistically distributed.

[0060] The Figure 9 The surface profile 3 shown as a grayscale image has a texture, whereby the shape and distribution of the elements 8 is irregular. Reference symbol (part of the description)

[0061] 1Product surface 2Incident light 3Surface profile 41Absorbed light 4Reflected light 5Code 6Cell of a cell type 7Cell of a cell type 8Element 9Element base 10Element tip 11Edge length of a code 12Edge length of a cell 13Distance 14Height difference 15Section 16Detector 20Pixels 21, 22, 23Pixels 25Field

Claims

1. Method for producing a product surface (1) of a product, wherein the product surface (1) has an opto-electronically readable code (5), which is formed by an arrangement of flat cells (6, 7) of different cell types, - wherein the cells (6, 7) are an integral part of the product surface (1), - wherein the cells (6, 7) of each cell type each have a surface profile (3), - wherein the surface profile (3) of at least one cell type has at least one elevation and / or depression relative to the product surface (1), - wherein the surface profile (3) of a first cell type is designed relative to the surface profile (3) of a second cell type such that the reflective properties of the surface profile (3) of the first cell type differ from the reflective properties of the surface profile (3) of the second cell type, - wherein the product surface (1) is formed from a polymer material, in particular from an elastomer material, and - wherein the product surface is the surface of a sidewall of a pneumatic vehicle tyre, characterized in that - the code (5) is a two-dimensional code, in particular a quick-response (QR) code or a stacked code or a matrix code or a point code, - in that, to produce the product, a moulding tool is used, wherein during the production of the product the code (5) is embossed in the product surface (1) by an appropriately designed shaping surface of the moulding tool, - and in that the moulding tool for producing the product is provided with a cutout in which an interchangeable punch formed so as to be complementary to the cutout can be interchangeably arranged, wherein the interchangeable punch has a shaping surface by which the code (5) is transferrable to the product surface.

2. Method according to at least one of the preceding claims, characterized in that the code (5) is formed from cells (6, 7) of two cell types.

3. Method according to at least one of the preceding claims, characterized in that the surface profile (3) of one cell type has elements (8) which form a structure and / or a texture.

4. Method according to at least the preceding claim, characterized in that a predominantly oriented or predominantly diffuse reflection is achieved by way of the structure and / or texture.

5. Method according to at least one of Claims 3 and 4, characterized in that light is able to be reflected several times on multiple elements (8).

6. Method according to at least one of Claims 3 to 5, characterized in that the shape of an element (8) is based on a web and / or a cylinder and / or a pyramid and / or a cone and / or a truncated pyramid and / or a truncated cone.

7. Method according to at least one of Claims 3 to 6, characterized in that the element tips (10) of two adjacent elements (8) have a spacing of 0.01 mm to 0.8 mm, particularly preferably a spacing of 0.06 mm to 0.3 mm.

8. Method according to at least one of Claims 3 to 7, characterized in that elements (8) of a surface profile (3) of one cell type have a height difference (14) of 0.08 mm to 0.5 mm, particularly preferably a height difference (14) of 0.15 mm to 0.3 mm.

9. Method according to at least one of the preceding claims, characterized in that the surface profile (3) of one cell type has regions with a roughness depth of at most 0.01 mm, preferably a roughness depth of at most 0.08 mm.

10. Method according to at least one of the preceding claims, characterized in that the surface profile (3) of one cell type corresponds to a surface profile (3) of the product surface (1).

11. Method according to at least one of the preceding claims, characterized in that the surface profiles (3) of the cell types of a code (5) differ in their roughness depth, in particular in that the ratio of the roughness depth of the surface profile (3) of a first cell type to the roughness depth of the surface profile (3) of a second cell type is at least 20, in particular at least 30.

12. Method according to at least one of the preceding claims, characterized in that cells (6, 7) have an additional height profile, wherein it is in particular an inclination and / or curvature of the cell surface and / or a lowering or raising of the cell surface relative to the product surface.

13. Method according to at least the preceding claim, characterized in that the shaping surface of the interchangeable punch is made of steel or silicone or coated with such a material.