Security document having a transparent window formed on a substrate of the security document

Abstract

The invention relates to a security document (02) having a transparent window (04) constructed in its substrate (26), wherein a micro-optical structure (03) consisting of micro-lenses (11) is arranged on one side of the substrate (26), at least in the region of the transparent window (04), and at least one printed image (27) is arranged on the other side of the substrate (26) opposite to the micro-optical structure (03), at least in the region of the transparent window (04), wherein the respective printed image (27) has a plurality of image elements (28a-28j) in the form of a dot-shaped or line-shaped grid, wherein the pixel size (38) or the line thickness (38) of the image elements (28a-28j) is respectively designed to be smaller than the lens width ( 18), wherein, at least on a part of the corresponding printed image (27), on the side of the corresponding printed image facing away from the micro-optical structure (03), a layer (39) is arranged which extends in a planar manner and covers the corresponding printed image (27), and the layer (39) covering the corresponding printed image (27) is generated in an inkjet printing process, wherein the layer (39) is designed to be transparent to electromagnetic radiation with a wavelength in the range of 380nm to 780nm, and the transmittance for electromagnetic radiation is in the range of 10% to 90%, and the transmittance is designed to gradually change on the two-dimensional planar extension of the layer (39) covering the corresponding printed image (27), so that: at least one part of the layer (39) or some parts of the layer (39) are designed with a transmittance different from other parts of the layer (39).

Description

Technical Field

[0001] The invention relates to a security document having a transparent window formed on its substrate. Background Art

[0002] A security substrate is known from US2018 / 0196980A1, which includes: a polymer substrate having a first surface and a second surface; an arrangement of focusing elements in the form of surface undulations above a first area of ​​the polymer substrate, the surface undulations being confined in the surface of a transparent base layer, the transparent base layer including the polymer substrate or a layer arranged thereon; an optical adaptation layer, which is arranged on a transparent base layer above a second area of ​​the polymer substrate, the second area including at least a first area, the optical adaptation layer having a first surface in contact with the surface undulations of the transparent base layer, and an opposite second surface, the second surface having a profile that cannot effectively focus visible light, wherein the optical adaptation layer The layer comprises a first transparent material extending over a first sub-region where the focusing elements are arranged, the first sub-region covering the entire first region or only a portion of the first region, wherein the first transparent material has a refractive index different from the refractive index of the transparent base layer, and the focusing elements in the first sub-region of the above structure are functional focusing elements; and the first transparent material has at least one first masking layer, which first masking layer comprises a reflective and / or opaque material arranged on an optically compatible layer above a third region of the polymer substrate, the third region defining at least one gap in the first masking layer, the gap comprising at least one segment of the first sub-region, so that the functional focusing elements in the structure are revealed through the at least one gap.

[0003] DE112009002538T5 discloses a device for accurately aligning an embossed security feature on a document, comprising: a) a first printing station for applying embossable printing ink to an area of ​​a substrate; b) a embossing station having a embossing mechanism for embossing at least a portion of the area of ​​the embossable printing ink while constituting an embossed security feature; wherein the first printing station is arranged to print an embossable ink registration area on the substrate, and the embossing mechanism is arranged to emboss at least a portion of the registration area while constituting a registration key; c) a printing mechanism for applying at least partially printed alignment marks to the substrate; d) a detection device for identifying the position of the registration key and for identifying the position of the registration mark; e) a comparison mechanism for comparing the relative positions of the alignment key and the alignment mark; and an adjustment mechanism for adjusting the position of the print medium relative to the embossing mechanism when the alignment key and the alignment mark are not accurately aligned.

[0004] A security device is known from US2019 / 0232708A1, which includes an arrangement of focusing elements with a regular periodicity in at least a first direction, each focusing element having an optical footprint, and different segments of the optical footprint are directed towards the viewer in relation to the viewing angle; an arrangement of image elements with a regular periodicity in at least the first direction overlaps with an arrangement of focusing structures, wherein the image elements represent segments of at least two corresponding images, and at least one image element of each corresponding image is located in the optical footprint of each focusing structure; the security device includes a first partition and a second partition offset laterally from the first partition, the image elements in the first partition being shifted laterally in at least the first direction relative to the image elements in the second partition, so that at a first viewing angle, in the first partition of the device, the focusing structure A picture element corresponding to a first image is directed toward a viewer so that the first image is displayed on a first partition of the device, and at the same time in a second partition of the device, a focusing structure directs a picture element corresponding to a second image toward a viewer so that the second image is displayed on the second partition of the device, and at a second viewing angle, the second image is displayed on the first partition of the device, and at the same time the first image is displayed on the second partition of the device, and the security device also includes a color filter used between the picture element and the observer, the color filter overlaps at least one segment of the arrangement of the focusing elements and the arrangement of the picture element, the color filter has a first color in the first partition of the device and a different color in the second partition of the device, so that the color display of the first image and the second image is different in the corresponding first and second partitions of the device.

[0005] EP2493700A2 discloses a method for producing a safety device, which comprises: providing an arrangement of lens-shaped focusing elements on one side of a transparent substrate; and providing a corresponding arrangement of groups of graphic strips on the other side of the transparent substrate, the graphic strips and the lens-shaped focusing elements defining a lens-like device, so that corresponding graphic strips from each group can be viewed through corresponding lens focusing elements under different viewing directions.

[0006] WO 2011 / 107783 A1 discloses a security document comprising: a document substrate having at least two transparent or see-through windows spaced apart from one another and a device comprising a transparent substrate carrying: i) a uniform arrangement of microfocusing elements on a first surface, wherein the focusing elements define a focal plane; ii) a corresponding first arrangement of micro-elements in a first color and in a plane substantially coinciding with the focal plane of the focusing elements; and, iii) a corresponding second arrangement of micro-elements in a color different from the first color and in a plane substantially coinciding with the focal plane of the focusing elements, wherein the pitch of the first and second arrangements of microfocusing elements and micro-elements and their relative positions are such that: the microfocusing elements The arrangement of the parts corresponds to each of the first and second arrangements of micro-elements so as to generate a corresponding enlarged version of the micro-elements of each arrangement according to the moiré effect; and at least one segment of the first arrangement of micro-elements does not overlap with the second arrangement of micro-elements, and at least one segment of the second arrangement of micro-elements does not overlap with the first arrangement of micro-elements; wherein the device is processed into the document substrate or applied thereto in alignment with at least two windows, and the device is registered relative to the document substrate so that the enlarged version of the first micro-element arrangement is visible through the first window of the two windows, and the enlarged version of the second micro-element arrangement is visible through the second window of the two windows, and the transition between the two micro-element arrangements is obscured by the document substrate between the two windows.

[0007] From DE 11 2010 000 957 T5 a lens array for imaging a plurality of picture elements in an object plane is known, the lens array comprising a plurality of microlenses which are formed in a transparent or translucent material with picture elements on the opposite side or arranged on one side, the lens array having a measured thickness corresponding to the distance from the vertex of each microlens to the object plane, each microlens having a set of lens parameters, wherein the measured thickness and / or at least one lens parameter is optimized so that each microlens has a focal point size in the object plane which is substantially equal to the size of the picture element in the object plane or deviates from the size of the picture element by a predetermined amount. In this case, the measured thickness of the lens array is preferably smaller than the focal length of all microlenses. The picture elements can, for example, be assumed in the form of points or lines. The lens array of DE112010000957T5 is designed so that: in a cone or angular field of light incident on the relevant microlens in the direction of the picture element and parallel to the main plane of the corresponding microlens, there is always only a single picture element arranged side by side with each other, whereby a viewer who views the printed image from a specific viewing angle can always perceive only a single frame at a certain point in time. Summary of the invention

[0008] The object of the present invention is to provide a security document having a transparent window formed in its substrate.

[0009] According to one aspect of the present invention, a security document has a transparent window constructed in its substrate, wherein a micro-optical structure composed of micro-lenses is arranged on one side of the substrate, at least in the area of ​​the transparent window, and at least one first printed image is arranged on the other side of the substrate opposite to the micro-optical structure, at least in the area of ​​the transparent window, wherein the corresponding first printed image has a plurality of image elements in the form of a dot-shaped or line-shaped grid, wherein the pixel size or line thickness of the image elements is respectively designed to be smaller than the lens width of the micro-lenses arranged in the micro-optical structure, wherein at least on a part of the corresponding first printed image, on the side of the corresponding first printed image facing away from the micro-optical structure, a layer extending in a planar manner and covering the corresponding first printed image is arranged, wherein the layer covering the corresponding first printed image is generated in an inkjet printing process. The layer is designed to be transparent to electromagnetic radiation with a wavelength in the range of 380nm to 780nm, and the transmittance to the electromagnetic radiation is in the range of 10% to 90%, and the transmittance is designed to gradually change over the two-dimensional planar extension of the layer covering the corresponding first printed image, so that: at least one portion of the layer or some portions of the layer are designed with a transmittance different from other portions of the layer, wherein a second printed image is arranged on the side of the layer that partially covers the first printed image facing away from the micro-optical structure, wherein the second printed image is arranged on the layer covering a portion of the first printed image, so that after the second printed image is folded at the fold line, it can overlap with the micro-optical structure applied on the other side of the substrate of the security document, so that when observed from the direction of the micro-optical structure, the second printed image or at least one information contained in the second printed image can be seen and / or can be identified. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Exemplary embodiments are shown in the drawings.

[0011] in:

[0012] Figure 1 A security document is shown having a security element with an optical imaging structure;

[0013] Figure 2 A strongly enlarged cross-sectional view of an arrangement having at least one printed image and individual plano-convex microlenses integrated into an optical imaging structure is shown, wherein light is incident from a first viewing angle.

[0014] Figure 3 Show according to Figure 2 An arrangement wherein light is incident from a second viewing angle.

[0015] Figure 4 A security document having a mechanism for self-authentication is shown;

[0016] Figure 5 A security document is shown with a reverse side having enhanced contrast;

[0017] Figure 6 A security document is shown with a reverse side having enhanced contrast and a mechanism for self-authentication;

[0018] Figure 7 Shown in particular according to Figure 5 A simplified schematic diagram of a printing press for producing security documents is shown in FIG. 6 . DETAILED DESCRIPTION

[0019] In optics, the term "lens" refers to a structural element that is transparent to light and has at least one light-refracting surface arranged in the optical path of the light. The term light here refers to the part of electromagnetic radiation that is visible to the human eye. In the electromagnetic spectrum, the range of light includes wavelengths from about 380 nm (violet) to 780 nm (red). The following is based on a converging lens, i.e. a lens that converges the incident light, in particular a lens of plano-convex design. Preferred configurations are, on the one hand, rotationally symmetrical lenses of spherical or non-spherical design and, on the other hand, axisymmetric rod lenses, wherein the corresponding symmetry axes of the relevant lenses are respectively distributed in agreement with their optical axes. The optical axis is therefore a straight line that generally extends through the center of curvature of the convex lens surface. For a flat lens surface, the optical axis is perpendicular to the lens surface. The curvature of a refracting, for example convex surface is given by its radius of curvature, wherein the origin of the radius of curvature is on the optical axis. A flat lens surface is defined by an infinite radius of curvature.

[0020] Rod lenses are designed in the form of right circular cylinders or elliptical cylinders, each divided by half of its rod length, wherein the respective axis of symmetry of such lenses extends orthogonally to its respective rod length. In the case of spherical lenses, the refractive surface is designed as a surface segment consisting of a sphere, i.e., for example, in the form of a spherical cap. Aspherical lenses have at least one refractive surface that deviates from a spherical or flat shape. The shape of rotationally symmetric aspherical shapes is usually given in the form of conic sections (circular, elliptical, parabolic, hyperbolic) plus correction polynomials for higher-order deformations.

[0021] The lens has two surfaces, so-called envelope surfaces, which intersect the optical path of the light. For light bundling, the definition applies as follows: the light enters a convex lens of plano-convex construction on its convexly curved envelope surface and the light exits the lens on the flat envelope surface of the lens. The envelope surface is the interface between different media in which the light propagates. One of these media is formed by a material, namely the material of the relevant lens. At least another medium is a space in which the relevant lens is located, which is generally filled with air. Since at least the optical material properties of at least two media arranged in the optical path are different from each other, the light is refracted at the interface between these adjacent media. Therefore, the light refraction occurs on at least one envelope surface of the respective lens, in particular on its curved envelope surface. The optical material properties related to the refraction of light are represented by the corresponding refractive index of the relevant medium. The refractive index is a dimensionless physical quantity that indicates by what factor the wavelength and phase velocity of light in the relevant medium are smaller than in a vacuum. Of the two media with different refractive indices that form a common interface, the medium with the higher refractive index is called the optically denser medium. The Abbe number (also called Abbe's number) is a dimensionless quantity that characterizes the optical dispersion properties of a lens and indicates the extent to which its refractive index varies with the wavelength of light. The properties of a lens capable of producing an optical image of an object viewed through the lens in question depend on the refractive index of the material of the respective lens and on the shape of its envelope surface that forms the interface between different media.

[0022] The principal plane of a lens is a plane arranged orthogonally to the axis of symmetry of the relevant lens in the structural element. In the case of a thin lens, in which its maximum extension along the axis of symmetry, i.e. the thickness of the lens, is considered to be very small compared to the radius of curvature of the convex envelope surface, since the radius of curvature of the convex envelope surface is, for example, at least five times greater than the thickness, only a single principal plane can serve as a basis for obtaining a sufficiently accurate observation of the characteristics of the relevant lens. In a plano-convex lens, the principal plane coincides with the flat lens surface. The focal length of a lens is the distance between the principal plane of the relevant lens and its focus (focusing point), wherein the focus of the lens is understood here as the point of intersection of the light rays incident parallel to the lens and converged by the lens. Here, the light rays incident parallel to the lens do not necessarily enter parallel to its optical axis, but at an arbitrary, in particular acute, angle of incidence relative to the principal plane of the relevant lens. The plane arranged orthogonally to the optical axis at the focus is called the focusing plane or focal plane.

[0023] The envelope surface of the relevant lens for the incidence of light has two opposite edge points, which delimit the envelope surface, for example, in the main plane of the lens, axially symmetrically with respect to its optical axis, and the distance between these two edge points determines the width of the relevant lens (= lens width). The aperture or opening width of a lens is its free opening or diameter through which light can be received unimpeded and corresponds at most to the lens width. The point at the intersection of the optical axis and the envelope surface of the relevant lens for the incidence of light is called the vertex. This vertex is arranged on the envelope surface for the incidence of light at the farthest distance from the focus of the lens.

[0024] A lens of rotationally symmetrical spherical or non-spherical construction focuses the light incident on it into a cone or pyramid, wherein the diameter of the base of the cone or pyramid is at most equivalent to the width of the lens and the height perpendicular to the base of the cone or pyramid is equivalent to the focal length of the relevant lens. A lens of axisymmetric rod-shaped design focuses the light incident on it into an acute angular field, the origin of which is located at the focus of the lens. The numerical aperture indicates the ability of a lens to focus light. The numerical aperture determines the minimum size of the light spot that can be produced at its focus and is therefore an important parameter for limiting the resolution.

[0025] A plurality of lenses, each of which is rotationally symmetrically constructed in a spherical or non-spherical shape, form a lens grid, also referred to as a lens array, which are arranged in a preferably uniform grid composed of square or hexagonal grid cells, in particular without gaps and overlaps. A plurality of lenses, each of which is axisymmetrically constructed in a rod-like shape, form a lens grid, also referred to as a biconvex lens, which are arranged side by side with each other orthogonally to their rod lengths, also preferably without gaps and overlaps. A plurality of lenses arranged in a grid-like lens grid and / or a plurality of lenses arranged in a lens grid, with their respective combinations, respectively form an optical imaging structure in the form of a geometric figure extending on a flat or curved surface. The surface of the optical imaging structure can have any profile, such as a rectangle, a circle, an ellipse or a polygon. In geometry, a geometric figure is regarded as a set of points. With reference to the optical imaging structure, a lens is respectively arranged on at least a subset of the points forming the geometric figure.

[0026] In an optical imaging structure, only one or more grid-shaped lens grids or only one or more lenses arranged in a lens grid and these two lens arrangements can be mixed with different lens arrangements, so that the grid-shaped lens grid and the lenses arranged in the lens grid are arranged together in the same optical imaging structure. For example, the lens grids constructed in the relevant optical imaging structure can also have different orientations, wherein the corresponding orientation of the relevant lens grid is determined by the corresponding direction of the rod length of the lens involved in the structure of the relevant lens grid.

[0027] Microlenses are miniaturized versions of conventional lenses. The term "microlens" is used to denote lenses with a lens width of less than 100 μm and preferably in the range of 20 μm to 65 μm. The focal length of a microlens is less than, for example, 100 μm, preferably a maximum of 95 μm. Microlenses can now be produced industrially. Microlenses made of synthetic materials or resins can be produced, for example, using a (spray) casting method or a (spray) embossing method or a printing method. An optical imaging structure composed of a grid of microlenses is also referred to as a micro-optical structure.

[0028] When an optical imaging structure, in particular formed by microlenses, is arranged in combination with a preferably flat printed image, different effects can be produced for an observer who views the printed image through the optical imaging structure by applying the optical imaging structure, for example, to a substrate having the printed image. For example, an arrangement consisting of at least one printed image and at least one optical imaging structure, such as a so-called shifted image or a shaking image (flip) (Wackelbilder (Flips)) and / or a spatial image, can be used, i.e. a three-dimensional effect and / or a deformation effect and / or a zoom effect and / or an animation can be achieved. These effects can be perceived without optical auxiliary devices when the observer views the printed image alternately from different viewing angles. The perception presented to the observer at different viewing angles is also called a biconvex lens image.

[0029] Generally, a planar printed image is preferably formed on a substrate of two-dimensional structure, for example, preferably by a printing machine in an industrial production process. The substrate is, for example, a web of printing material or is designed to print a single sheet of paper. Therefore, the printed image is applied to the substrate, for example, in the form of a dot-shaped or line-shaped grid. Therefore, the printed image consists of a plurality of, in particular a large number of, pixels and / or lines, for example. Here, the pixel size or line thickness is less than 100 μm, preferably less than 50 μm, in particular less than 20 μm, for example in the range of about 5 μm to 10 μm. In the following, it is assumed that the pixel size of the pixels and / or the line thickness of the lines respectively related to the composition of the printed image used with the optical imaging structure (for example, the optical imaging structure) are, for example, at most as large as the corresponding lens width of the lens involved in the construction of the relevant optical imaging structure, preferably smaller, in particular less than half thereof.

[0030] In optics, resolution is the ability to distinguish fine structures, i.e. the minimum distance that two pixels or two lines must be apart in order to be perceived as separate pixels or lines. The resolution of the human eye varies from person to person. An adult with normal vision can usually distinguish structures that are 150 micrometers apart at a distance of 25 centimeters. This corresponds to a viewing angle of about 2 arc minutes, which is called angular resolution. At low contrasts, the visual acuity of the human eye decreases significantly, and visual acuity is expressed as the inverse of the resolution. The lens width of a microlens is usually smaller than the resolution of an adult with normal vision.

[0031] In order to produce a color printed image, a substrate is printed with a plurality of printing inks, for example, printing inks called primary colors red, green, blue and, if necessary, black are formed on the substrate. The printed image usually consists of an arrangement of a plurality of small-area picture elements arranged at different positions of the relevant printed image, each picture element preferably having a plurality of pixels or lines and generally extending for a length of less than 100 μm. Each picture element or a group of adjacent picture elements, for example, forms an object that can be observed through a lens. The individual picture elements are generally arranged in the printed image to form a printed subject matter that determines the information content of the printed image. Due to their limited, generally insufficient resolution, the individual picture elements used in combination with microlenses are usually not perceptible to the naked eye. The color impression of the printed image or at least a segment of the printed image perceived by the person is achieved by the additive color mixing of the pixels and / or lines printed in the relevant picture elements respectively with different printing inks, which occurs in the eyes and brain of the viewer. The superposition of two primary colors produces the color impressions of yellow, cyan and magenta, which are called secondary colors. The superposition of all three primary colors produces the impression of white. In embodiments of the present invention, the color registration, i.e. the plate matching, i.e. the matching accuracy of pixels and / or lines of different printing inks in their relative arrangement to each other is respectively less than 20 μm, preferably less than 10 μm, and in particular is in the range of about 5 μm.

[0032] The optical imaging structure provided in conjunction with the embodiments of the invention considered here is preferably arranged in combination with pixels and / or lines of different printing inks. The printed image is preferably produced as or by the superposition of a plurality of sub-printed images, wherein a plurality of or preferably each sub-printed image is, for example, printed with a different printing ink. The superposition can be achieved by continuous overprinting onto a substrate or preferably by collecting the sub-printed images on a printing element (e.g. a roller) and simultaneously transported to the substrate. The sub-printed images in turn consist of pixels and / or lines, the pixel size of these pixels and / or the line thickness of the associated lines being in the micrometer range, for example in the micrometer range. For example, in the range of less than 20 μm. For a viewer viewing the printed image, in terms of their perception, the plurality of sub-printed images involved in the printed image are superimposed, for example forming an overall color impression.

[0033] An arrangement consisting of at least one printed image and at least one optical imaging structure enables a viewer viewing the printed image to perceive multiple different single images from different viewing angles, wherein a series of single images are perceived by the viewer as alternating images or shaking images (flipping) and / or spatial images, i.e., three-dimensional effects and / or deformation effects and / or zoom effects and / or animations. Each of these individual images is also referred to as a frame. The image perceived by the viewer at a certain viewing angle is generated by the optical imaging structure from a group of sub-printed images, which are determined by the optical imaging structure from a plurality of sub-printed images perceptible at corresponding positions of microlenses based on at least one image element there or a plurality of image elements there, wherein the overall color impression associated with the position of the printed image is generated by superimposing all sub-printed images present and perceptible at that position. Therefore, the optical imaging structure arranged in combination with the printed image is an optical masking portion of the sub-printed image of the relevant printed image, which is arranged overlapping with the surface of the optical imaging structure.

[0034] In order to allow a viewer of the printed image to see multiple frames simultaneously at a certain viewing angle, for example to achieve more complex and / or more differentiated animations, for example, an arrangement having a printed image and an optical imaging structure composed of a plurality of plano-convex microlenses is used, wherein a plurality of, preferably more than three, in particular five to ten image elements are arranged side by side under at least one microlens of the relevant optical imaging structure, and these image elements are arranged between the lens width extension of the relevant microlens and its focus in a cutting plane parallel to the main plane of the relevant microlens, and the cutting plane is arranged to intersect with a cone or angular field of light incident through the lens width of the relevant microlens toward the image elements arranged side by side, wherein, in the cutting plane, a plurality of different image elements are arranged side by side at the same time within the cone or angular field.

[0035] Thus, an arrangement is obtained having a printed image and an optical imaging structure composed of a plurality of plano-convex microlenses, each of these microlenses having a lens width along the printed image that is preferably less than 100 μm, wherein the printed image has a plurality of picture elements, wherein a plurality of picture elements are respectively arranged below at least one microlens of the relevant optical imaging structure, and these plurality of picture elements arranged below at least one of the microlenses of the relevant optical imaging structure are arranged side by side with each other along the lens width and extend respectively in the direction of the lens width over a length shorter than the relevant lens width, wherein, between the extension of the lens width of the relevant microlens and its conical or angular focus, in a cutting plane in a cone or angular field of light that is incident through the lens width of the relevant microlens in the direction of picture elements arranged adjacent to each other and parallel to the main plane of the relevant microlens, a plurality of, preferably at least three, and in particular more than three, different picture elements are simultaneously arranged side by side with each other. With this arrangement, a viewer of the printed image can perceive multiple frames simultaneously at a certain viewing angle, which produces complex and / or differentiated animations and smooth color transitions in the case of sliding of graphic elements of corresponding color designs, and / or smooth frame transitions in the case of different printed themes formed by graphic elements.

[0036] The substrate is, for example, a fibrous printing material, in particular paper or a film, preferably a polymer film. The substrate can be opaque or transparent. The substrate can be designed as a single layer or multiple layers, in particular as a multilayer design in sections. The different layers in the multilayer substrate can be made of different materials, for example a layer of paper and another layer of a polymer film. The substrate or at least one corresponding layer of the substrate has a material thickness, i.e., a thickness of, for example, less than 100 μm, preferably less than 50 μm, in particular about 25 μm. The printed image formed on the substrate has a layer thickness of, for example, less than 10 μm, preferably less than 5 μm, in particular in the range of 1 μm to 2 μm. The substrate can be printed on one side or both sides.

[0037] In a preferred embodiment of the invention, the arrangement of the printed image and the optical imaging structure is part of a security element or document, in particular a security document. These documents include, for example: banknotes, credit cards, checks, securities, stocks, passports, identity cards, driver's licenses, property certificates, travel documents (such as airline or train tickets), tickets, academic certificates and other official or formal documents such as birth, death or marriage certificates. This list is only an example and is not exhaustive. However, it is preferably related to banknotes.

[0038] Figure 1By way of example, a document 02, in particular a security document 02, is shown on or in which at least one security element 01 is arranged. The document 02 and / or the associated security element 01 has at least one optical imaging structure 03 on a partial surface or on the entire surface thereof, wherein the respective optical imaging structure 03 is preferably designed as a micro-optical structure 03 formed by microlenses 11. The associated optical imaging structure 03 is arranged in such a way that it at least partially covers a printed image 27 constructed or applied to the document 02, for example.

[0039] Figure 2 By way of example, a greatly enlarged sectional view, in particular as Figure 1 The partial view of the security element 01 or document 02 shown shows an arrangement with individual plano-convex microlenses 11, which are integrated into a combination of microlenses 11 or in a grid. The respective microlens 11 has an axis of symmetry 12 which also forms the optical axis 12 of the microlens 11. The microlens 11 can be designed rotationally symmetrically to be spherical or non-spherical, or can be designed, for example, axisymmetrically to be rod-shaped, in which case the axis of symmetry 12 extends orthogonally to the length of the rod in the case of an axisymmetric rod-shaped microlens 11. The microlens 11 is made, for example, of a transparent synthetic material or resin by injection, casting, die-casting or printing. The microlens 11 has a convex envelope surface 13 for the incidence of light, wherein, for example, a bundle of parallel light rays 14 impinges on this envelope surface 13. The microlens 11 has two opposite edge points 16; 17, which delimit the convex envelope surface 13, axially symmetrically with respect to its optical axis 12 passing through the vertex 37 of the convex envelope surface 13, wherein the distance between the two edge points 16; 17 determines the width of the microlens 11, which is called the lens width 18. The lens width 18 of the microlens 11 is less than 100 μm. The two edge points 16; 17 of the convex envelope surface 13 are located in a plane arranged orthogonally to the optical axis 12 of the associated microlens 11, which plane is also called the main plane 19 of the microlens 11. Figure 2 In the embodiment shown in , the main plane 19 forms a flat envelope surface 21 of the associated microlens 11. The distance between the main plane 19 of a microlens 11 and its focus 23 (focal point) forms the focal length 22 of the associated microlens 11, wherein the focus 23 is the intersection point of the bundled, in particular parallel, light rays 14 incident into the microlens 11. The focal length 22 of the microlens 11 is less than 100 μm. The plane arranged orthogonally to the optical axis 12 in the focus 23 is referred to as the focal plane 24.

[0040] exist Figure 2In the embodiment shown, the microlenses 11 are part of a lens array or a lens grid in which a large number of microlenses 11 are arranged in relation to a certain surface of an arbitrary profile, preferably without gaps and without overlap. The lens array or the lens grid is arranged on a substrate 26, wherein the substrate 26 is designed, for example, as a fibrous printing material with a transparent window, in particular paper, or as a film, preferably as a transparent polymer film. The substrate 26 has a material thickness 29 or thickness 29 of, for example, less than 100 μm, preferably less than 50 μm, in particular about 25 μm. The substrate 26 is preferably part of a security element 01 or a document 02, in particular a security document 02. The substrate 26 is designed to be transparent at least in the area covered by the flat envelope surface 21 of the respective microlenses 11.

[0041] exist Figure 2 In the embodiment shown, a printed image 27 with a small layer thickness 36, for example less than 10 μm, is applied to the back of the substrate 26, that is, on the side of the substrate 26 facing away from the microlenses 11, which printed image 27 has a large number of individual different image elements 28. These individual image elements 28 are designed with very small areas and extend parallel to the lens width 18 only over a few micrometers, for example over a maximum of 10 μm. It is therefore possible that a plurality of, for example, ten such image elements 28a-28j are arranged, for example, next to each other, in the area covered by the flat envelope surface 21 of the microlenses 11. At least one of these image elements 28a-28j preferably has pixels and / or lines printed with different printing inks, in particular, depending on the number of image elements 28a-28j arranged next to each other, the respective pixels have a pixel size 38 and / or the lines have a line thickness 38, each in the range of a few micrometers, preferably in the range of less than 20 μm. The printed image 27 preferably consists of an overprint or superposition of a plurality of sub-print images, each printed with different printing inks. The picture elements 28 a - 28 j arranged next to one another in the region covered by the planar envelope surface 21 of the microlenses 11 , ie below the respective microlenses 11 , preferably each correspond to a different printed subject matter.

[0042] The picture elements 28a-28j arranged, for example, side by side below the respective microlens 11 are advantageously arranged closer to the microlens 11 than the focal point 23 of the microlens 11. These picture elements 28a-28j are preferably arranged between the respective microlens 11 and its focal point 23 in a cutting plane 31 arranged parallel to the main plane 19 of the respective microlens 11, wherein the cutting plane 31 is arranged intersectingly with a cone 32 or an angular field 32 of light incident through the lens width 18 of the respective microlens 11 in the direction of, for example, the picture elements 28a-28j arranged side by side, wherein in the intersection plane 31 within the cone 32 or the angular field 32, a plurality of picture elements 28a-28j are preferably arranged side by side at the same time. Figure 2In the embodiment shown, within the cone 32 or angular field 32, for example, five picture elements 28c to 28g are arranged side by side, while the remaining picture elements 28a, 28b and 28h to 28j arranged in the area covered by the flat envelope surface 21 of the microlens 11 are not perceptible to a viewer viewing the printed image 27 at a first viewing angle 33 corresponding to the incident light 14, for example an acute angle. If the viewing angle for the viewer viewing the printed image 27 is now changed to a second viewing angle 34, for example an obtuse angle, which is different from the first viewing angle 33, then the picture elements 28a-28j that can be perceived by the viewer also change. This is in Figure 3 It is shown in Figure 2 The same arrangement has a printed image 27 and an optical imaging structure 03 composed of a plurality of plano-convex microlenses 11. Since the second viewing angle 34 is different from the first viewing angle 33, Figure 3 In the embodiment shown in , only the picture elements 28 d to 28 h are perceptible to a viewer viewing the printed image 27 , while the other picture elements are not perceptible.

[0043] As mentioned, in Figure 2 and Figure 3 The picture elements 28a-28j shown in the figure, which are arranged in the area covered by the flat envelope surface 21 of the individual microlenses 11, are formed by pixels and / or lines, which are preferably printed with different printing inks. In general, the respective pixel size 38 of the relevant pixel and / or the line thickness 38 of the relevant line are significantly smaller than the lens width 18 of the respective microlens 11, preferably in the range of a few micrometers, in particular in the range of less than 20 μm. In particular, in order to design the printed image 27 containing these picture elements 28a-28j to be machine-readable, at least one of these picture elements 28a-28j has pixels and / or lines, for the printing of which a special printing fluid, in particular an ink, is used, which differs from conventional printing fluids, in particular from conventional printing inks or inks, in terms of its own optical properties. These special printing fluids are, for example, inks that are invisible to the naked eye of a normal-sighted observer without an excitation outside the electromagnetic spectrum visible to the human eye, in particular inks that absorb infrared radiation or inks that reflect infrared radiation or convert infrared radiation into visible radiation or ultraviolet fluorescent inks or magnetic inks. These inks, which are particularly invisible under daylight conditions, can nevertheless be perceived, like other printing inks, in different shades, for example in the blue, green or red range, after appropriate stimulation. The stimulation is preferably electromagnetic or magnetic.

[0044] The term "ink" is understood here to mean a liquid that is densely dyed and colored, which is usually composed of a solution or dispersion of a colorant in water or other solvents, which does not contain a binder, or in the case of an ink designed as ink, contains a small amount of binder. A colorant is a coloring substance, such as a pigment and a dye, which can be inorganic or organic, natural or synthetic. In contrast, a printing ink is a mixture containing a colorant, which is applied to a substrate, that is, transferred to a substrate by means of a printing plate, that is, transferred to a printing material. Printing ink contains inorganic and organic pigments, such as titanium dioxide as a white pigment or carbon black as a black pigment, and a binder that encapsulates the pigment. Traditional printing inks and inks, together with inks that are invisible to the human eye under daylight conditions, can all be included in the term printing fluid.

[0045] The above-mentioned special inks that react to infrared radiation (IR) are used, for example, in combination with electromagnetic radiation from the near infrared range (NIR), wherein preferably radiation with a wavelength in the range between 780 nm and 2000 nm, in particular in the range between 780 nm and 1200 nm, is used. Ink reactive to infrared radiation (IR; NIR) contains, for example, inorganic, generally pigment-like luminophores which, after absorbing energy, emit radiation in the visible spectrum and / or in the infrared range (NIR). Inks that convert infrared radiation into visible light contain so-called anti-Stokes pigments.

[0046] Ultraviolet radiation, or UV radiation for short, is a type of electromagnetic radiation that is invisible to the human eye and has a shorter wavelength than visible light. According to the widely accepted classification, the UV spectrum includes wavelengths from 100nm to 380nm, i.e. from the short-wave range to the border of visible light. Inks that fluoresce UV contain fluorescent pigments that glow strongly when exposed to UV radiation and, when necessary, use the ultraviolet rays of sunlight.

[0047] Magnetic ink is understood to mean an ink mixed in particular with iron oxide particles. These particles can be magnetized by a magnetic field external to the relevant substrate 26 and the optical imaging structure 03, which is different from the earth's magnetic field, and can therefore be analyzed and read magneto-optically.

[0048] An arrangement of an optical imaging structure 03 which is advantageous in terms of machine readability and has a printed image 27 applied to a substrate 26 and covers at least part of the printed image 27 is provided in that the optical imaging structure 03 has a group or grid of a plurality of plano-convex microlenses 11, the flat envelope surface 21 of the microlenses 11 facing the substrate 26, wherein the printed image 27 arranged on the substrate 26 is preferably arranged on its side facing the optical imaging structure 03 and has at least one picture element 28a to 28j, said picture element having at least one pixel and / or one line, wherein the pixel and / or the line is formed according to the printing technology by a printing fluid which is visible to the human eye only due to excitations which lie outside the electromagnetic spectrum visible to the human eye. The printing fluid is preferably formed as an infrared radiation absorbing ink or an infrared radiation reflecting ink or an ink which converts infrared radiation into visible radiation or an ultraviolet radiation fluorescent ink or a magnetic ink. Thus, the relevant at least one picture element 28a-28j of the machine-readable printed image 27 is an integral component of the relevant arrangement, for example on the security element 01 or the document 02, in particular on the security document 02. The excitation of the printed fluid outside the electromagnetic spectrum visible to the human eye is carried out on the front side in relation to the optical imaging structure 03 covering at least part of the printed image 27, i.e. directed towards the corresponding convex envelope surface 13 of the microlens 11, in which case the excitation is designed to act through the optical imaging structure 03, or on the back side, i.e. on the substrate side or directed towards the corresponding flat envelope surface 21 of the microlens 11, in which case the optical imaging structure 03 is designed to block the excitation.

[0049] If it is provided that a printed fluid which is only visible to the human eye based solely on excitations outside the electromagnetic spectrum visible to the human eye should not interact with the microlenses 11 of the optical imaging structure 03, then in such an arrangement the corresponding pixel size 38 of the relevant pixel and / or the line thickness 38 of the relevant line z is, for example, respectively larger than the lens width 18 of the corresponding microlens 11.

[0050] Furthermore, it can be provided that in a relevant arrangement consisting of a substrate 26 and an optical imaging structure 03 at a plurality of individual positions in a group of a plurality of plano-convex microlenses 11 or in a grid of a plurality of plano-convex microlenses 11, in the respective optical imaging structure 03, the respective microlenses 11 remain unstructured and at least one picture element 28a-28j of a printed image 27 having at least one pixel and / or line is arranged at the relevant missing location, the pixel and / or line being composed of a printing fluid that is visible to the human eye only based on an excitation outside the electromagnetic spectrum visible to the human eye in terms of printing technology. Thus, a printing fluid that is invisible to the human eye under normal conditions is applied or arranged at selected missing locations in the respective optical imaging structure 03.

[0051] As mentioned, the arrangement of the substrate 26 and the optical imaging structure 03 can have a printed image 27, which allows an observer with normal vision who views the printed image 27 with the naked eye through the optical imaging structure 03 to perceive multiple different single images at different viewing angles, wherein a series of single images appear in the viewer's perception as alternating images or shaking images (flipping) and / or spatial, i.e. three-dimensional effects and / or deformation effects and / or zoom effects and / or animations. These different single images are also called frames. These aforementioned effects are based on multiple sub-printed images, and at least one related printed image 27 is composed of multiple sub-printed images. In order to form an arrangement consisting of a substrate 26 and an optical imaging structure 03 with at least one machine-readable printed image 27, it is provided that the related printed image 27 has multiple sub-printed images at least in the area covered by the optical imaging structure 03. At least one of the sub-print images has a picture element 28a-28j, which has at least one pixel and / or one line, the relevant pixel and / or the relevant line being respectively formed in terms of printing technology by a printing fluid that is visible to the human eye only due to an excitation outside the visible electromagnetic spectrum. In an alternative or additional design, it can be provided that the machine-readable printed image 27 and at least one picture element 28a-28j of at least one of the plurality of sub-print images is formed by a mixed solution, wherein the mixed solution contains a printing fluid that is visible to the human eye, in particular under daylight conditions, and a printing fluid that is visible to the human eye only due to an excitation outside the electromagnetic spectrum visible to the human eye.

[0052] In addition, in order to form an arrangement having at least one machine-readable printed image 27, it can be configured as follows: in such an arrangement having a substrate 26 having a printed image 27 and a structure 03 for optically imaging the printed image 27, in a first area covered by the optical imaging structure 03, the graphic elements 28a-28j of the printed image 27 arranged therein are respectively formed by a printing fluid that is visible to the human eye, in particular under daylight conditions, and in a second area covered by the optical imaging structure 03, the graphic elements 28a-28j of the printed image 27 arranged therein are respectively formed by a printing fluid that is visible to the human eye only based on excitation outside the electromagnetic spectrum visible to the human eye.

[0053] Regardless of the corresponding design of the substrate 26 and / or the optical imaging structure 03 constructed thereon and / or the corresponding design of the printing fluid for forming at least one printed image 27, whether it is a printed image that is visible to the human eye, in particular under daylight conditions, or a printed image that is visible to the human eye only based on excitations outside the electromagnetic spectrum visible to the human eye, or in order to form a security element 01 or a security document 02, the above-mentioned two types of printing fluids are used together to achieve the same printed image 27, as described below.

[0054] Figure 4An example of a security document 02 is shown, such as a banknote, whose substrate 26 is composed of a fibrous printing material, in particular paper, and has at least one transparent window 04. Alternatively, the substrate 26 of the security document 02 can also be a film, preferably a transparent polymer film or a film with a transparent window 04. On one side of the security document 02, at least in the region of the relevant transparent window 04, a micro-optical structure 03 is arranged, which partially or completely covers the window 04. The micro-optical structure 03 is designed as a lens array or a biconvex lens, which is composed of plano-convex microlenses 11 respectively.

[0055] In the case of a lens array and, for example, in the case of a biconvex lens, these microlenses 11 are rotationally symmetrical spherical or non-spherical, for example, axially symmetrically rod-shaped. Outside the area of ​​the transparent window 04 and spaced apart from it, on the other side of the security document 02, that is, on the side of the security document 02 that does not have the aforementioned lens array or biconvex lens, a printed image 27 is formed or applied, which is formed or applied in particular by a printing fluid visible to the human eye, in particular under daylight conditions, or is composed of a printed image that is visible to the human eye only based on excitations outside the electromagnetic spectrum visible to the human eye. The relevant printed image 27 can contain information that can be immediately recognized by a person or can be designed as machine-readable information. The printed image 27 is applied to the substrate 26 in a grid composed of image elements 28a-28j, for example in a dotted or linear form, and preferably in an industrial printing method. For example, it is implemented in a lithographic method. The pixel size 38 or line thickness 38 of the image elements 28a-28j of the printed image 27 applied to the substrate 26 is smaller than the lens width 18 of the microlenses 11 arranged in the lens array or lenticular lens and is therefore significantly smaller than 100 μm, preferably about 20 μm or less. If the window 04 partially or completely covered by the micro-optical structure 03 also has another printed image 27 on the back side of the substrate 26 of the security document 02, i.e. on the side of the substrate 26 of the security document 02 facing away from the micro-optical structure 03, which is preferably also realized using a lithography method, the other printed image 27 has at least one unprinted surface, i.e. a recess 06, in the area of ​​the other printed image 27 arranged in the transparent window 04, in the area covered by the micro-optical structure 03, so that the relevant recess 06 in the other printed image 27 arranged in the area of ​​the window 04 partially exposes the micro-optical structure 03 applied to the substrate 26 of the security document 02 and opens up the view through the transparent window 04 to the corresponding flat envelope surface 21 of the plano-convex microlenses 11 arranged in the micro-optical structure 03.

[0056] The method for authenticating a security document 02 having a micro-optical structure 03 now consists in: Figure 4As indicated by the arrow in the figure, the security document 02 is folded at a fold line 07 which preferably passes through the security document 02, and thereby the printed image 27 which is constructed or applied outside the area of ​​the transparent window 04 and spaced therefrom overlaps or is at least capable of overlapping with the micro-optical structure 03 applied on the other side of the substrate 26 of the security document 02 or at least with the recess 06 in the printed image 27 arranged in the area of ​​the transparent window 04 which partially exposes the micro-optical structure 03. Figure 4 As shown in , the substrate 26 of the security document 02 is folded at a fold line 07, for example, approximately in half, so that the folded portion of the substrate 26 having the printed image 27 applied outside the region of the transparent window 04 and at a distance therefrom is placed or at least can be placed on another portion having the transparent window 04 and the micro-optical structure 03. By folding the substrate 26 of the security document 02, the printed image 27 applied outside the region of the transparent window 04 and at a distance therefrom in the transparent window 04 of the substrate 26 of the security document 02 is placed on the corresponding flat envelope surface 21 of the plano-convex microlenses 11 arranged in the micro-optical structure 03.

[0057] If necessary, by performing a relative movement of the micro-optical structure 03 and a printed image 27 overlapping the micro-optical structure 03 and applied outside the area of ​​the transparent window 04 and at a distance therefrom, or by performing a turning movement of the entire security document 02 folded on the fold line 07, the printed image 27 or at least the information contained therein is visible or recognizable when looking through the fold line from the direction of the convex envelope surface 13 at the relevant printed image 27. Figure 4 For example, it is indicated by the symbol "&", which is preferably human-readable.

[0058] The advantage of the solution found is that the security document 02 can be authenticated without the aid of external means. Therefore, the proposed method enables the relevant security document 02 to be self-authenticated based solely on the mechanisms or means that the relevant security document 02 itself has. Therefore, the authentication proposed here is a proof that can be performed at any time and anywhere: the relevant security document 02 is an original, in particular a genuine banknote.

[0059] It can be found that the printed image generated on the back side of the substrate 26, i.e. on the side of the substrate 26 facing away from the micro-optical structure 03, in the area of ​​the transparent window 04 with a printing fluid that is generally visible to the human eye, especially under daylight conditions, cannot sometimes be recognized well enough, especially under weak light conditions, such as dim lighting conditions, when observing the relevant printed image 27 through the relevant micro-optical structure 03 from the direction of the convex envelope surface 13.

[0060] In order to improve the legibility of such a printed image 27, in particular for the human eye, it is proposed that the printed image 27 produced on the back side of the substrate 26 in the region of the transparent window 04 is overprinted with a printing fluid that has a lighter tone than the printing fluid 27 used to produce the relevant printed image 27. If the printed image 27 produced on the back side of the substrate 26 in the region of the transparent window 04 is produced by printing fluids of a plurality of different tones, then for overprinting the printed image 27 produced in this way, a printing fluid is used that has a lighter tone than the lightest tone of the printing fluid used to produce the relevant printed image 27. Preferably, the printed image 27 applied on the back side of the substrate 26 in the region of the transparent window 04 is at least partially overprinted with a layer 39 of white ink. This layer 39 forms a planar, extended covering layer of light-colored, in particular white, ink for the printed image 27 applied on the back side of the substrate 26 in the region of the transparent window 04. Here, the cover layer can be opaque, i.e., impermeable, i.e., opaque to electromagnetic radiation in the wavelength range of approximately 380 nm (violet) to 780 nm (red), or partially transparent to electromagnetic radiation in the wavelength range of approximately 380 nm (violet) to 780 nm (red). The partial transparency can be designed to change gradually or stepwise over the two-dimensional surface extension of the cover layer, so that some locations of the cover layer are designed to be more transparent than other locations of the cover layer. The transparency to incident light can preferably be in the range between 10% and 90%.

[0061] Therefore, as in Figure 5As shown in the example, a security document 02 is formed with a transparent window 04 formed in its substrate 26, wherein a micro-optical structure 03 consisting of micro-lenses 11 is arranged at least on one side of the substrate 26 in the region of the transparent window 04, and at least one printed image 27 is arranged on the other side of the substrate 26 opposite to the micro-optical structure 03. Here, the relevant printed image 27 has a plurality of image elements 28a-28j in a dot-shaped or line-shaped grid, which are formed in a hue different from white. The pixel size 38 or line thickness 38 of these image elements 28a-28j is respectively designed to be smaller than the lens width 18 of the micro-lenses 11 arranged in the micro-optical structure 03. In order to enhance the contrast, it is now provided that at least on a partial surface, that is, on a part of the relevant printed image 27, on its side facing away from the micro-optical structure 03, a layer 39 extending in a planar manner and covering the relevant printed image 27 is arranged, which layer 39 is composed of a lighter hue than at least one hue different from white that constitutes the relevant printed image 27. As mentioned above, the layer 39 covering the relevant printed image 27 can be designed to be opaque to electromagnetic radiation with a wavelength in the range of 380nm to 780nm, or the layer 39 can be transparent to electromagnetic radiation with a wavelength in the range of 380nm to 780nm, wherein the transparency to electromagnetic radiation is, for example, in the range between 10% and 90%. In addition, the transparency can be designed to change gradually or stepwise over the two-dimensional surface extension of the layer 39 covering the relevant printed image 27, so that some positions of the layer 39 are designed to have a different transparency than other positions of the layer 39. Thus, certain graphic elements 28a-28j of the relevant printed image 27 are emphasized due to their improved recognizability for the human eye, while other graphic elements 28a-28j of the relevant printed image 27 are intentionally kept weaker in terms of their respective recognizability. In a preferred embodiment, the layer 39 covering the associated printed image 27 is produced in an inkjet printing method, in a lithographic printing method or in a screen printing method, while the associated printed image 27 arranged on the other side of the substrate 26 opposite the micro-optical structure 03 is realized in a lithographic printing method.

[0062] By overprinting the printed image 27 applied on the back side of the substrate 26 in the region of the transparent window 04, the contrast between the picture elements 28a-28j contained in the printed image 27, i.e. its pixels and / or lines and their respective immediate surroundings, is increased. Contrast is generally the difference in brightness between adjacent light and dark areas in an image. By overprinting the printed image 27 applied on the back side of the substrate 26 in the region of the transparent window 04 with a layer 39 made of a light-colored, in particular white ink, the contrast of a plurality, preferably a majority, in particular all of the picture elements 28a-28j in the relevant printed image 27 is increased when the relevant printed image 27 is observed through the micro-optical structure 03 from the direction of the convex envelope surface 13, so that the printed image 27 or at least the information contained therein is or can be better recognized by the human eye even under weak light conditions, for example dim lighting conditions.

[0063] In a particularly advantageous embodiment of the invention, a security document 02 is obtained having a layer 39 on the back side of the substrate 26 which enhances the contrast and a mechanism for self-authentication, such as Figure 6 As shown in the cross-sectional diagram and described below.

[0064] Figure 6 Shown in Figure 5 The security document 02 shown by way of example in FIG. 1 has a transparent window 04 constructed in its substrate 26, wherein a microlens structure 03 composed of microlenses 11 is arranged on one side of the substrate 26, at least in the region of the transparent window 04, and a first printed image 27 is arranged on the other side of the substrate 26 opposite to the microlens structure 03. Also in this embodiment, the first printed image 27 has a plurality of image elements 28a-28j in a dot-shaped or line-shaped grid, and these image elements 28a-28j are preferably formed in a color tone different from white. The pixel size 38 or line thickness 38 of these image elements 28a-28j is respectively designed to be smaller than the lens width 18 of the microlenses 11 arranged in the micro-optical structure 03. Here, also for contrast enhancement, it is provided that: at least on a partial area or a segment of the first printed image 27, on the side facing away from the micro-optical structure 03, a layer 39 extending in a planar manner and covering the surface of the first printed image 27 is arranged, and the layer 39 is preferably composed of a lighter color than at least one color different from white that constitutes the first printed image 27.

[0065] Now according to Figure 6 The proposed safety document 02 and Figure 5The embodiment shown in FIG. 1 differs in that a second, i.e. another, preferably also lithographically generated, printed image 41 is arranged on the side of the layer 39 partially covering the first printed image 27 facing away from the micro-optical structure 03. The second printed image 41 is arranged on the layer 39 covering a portion of the first printed image 27 in such a way that the second printed image 41 is not embodied in the micro-optical structure 03. Figure 6 After the folding at the fold line 07 which preferably runs through the security document 02, as indicated by the arrow in FIG. Figure 4 As shown in the example in FIG. 1 , the micro-optical structures 03 applied on the other side of the substrate 26 of the security document 02 overlap or are at least capable of overlapping, so that the second printed image 41 or at least one information contained therein is visible and / or recognizable when viewed from the direction of the micro-optical structures 03. The fold line 07 on which the substrate 26 of the security document 02 is folded is preferably arranged outside the layer 39 partially covering the first printed image 27, i.e., arranged at a distance from the layer 39. The fold line 07 is preferably arranged in a portion of the first printed image 27 that is not covered by the layer 39 arranged on the first printed image 27.

[0066] According to the present invention Figure 6 In the embodiment, it can also be arranged that: the graphic elements 28a-28j of the first printed image 27 are formed in a tone different from white, wherein the layer 39 that partially covers the first printed image 27 is composed of a tone lighter than at least one tone different from white that constitutes the first printed image 27.

[0067] In addition, the present invention is based on Figure 6 The embodiments have at least some of the combined Figure 1 and Figure 5 Features introduced.

[0068] Reference Figure 7 , now explain: how can we especially according to Figure 5 or Figure 6The security document 02 is produced according to the embodiment shown. As already mentioned, the layer 39 covering the relevant printed image 27, in particular the contrast-enhancing layer 39, can also be produced by a lithographic method or a screen printing method, although in a preferred embodiment this layer is produced by an inkjet printing method, while the relevant printed image 27 arranged on the other side of the substrate 26 opposite the micro-optical structure 03 is produced by a lithographic method. In this case, the printed image 27 consists of a plurality of image elements 28a-28j printed with at least two different printing inks, which in themselves constitute pixels and / or lines. The pixel size 38 or the line thickness 38 is preferably in the range of less than 20 μm, for example in the range of about 5 μm to 10 μm. The color registration of the image elements 28a-28j, respectively printed with different printing inks, i.e. the accuracy of their relative arrangement to each other, is in the embodiment considered here respectively less than 20 μm, preferably less than 10 μm, and in particular in the range of about 5 μm.

[0069] The production of the printed image 27 with the aforementioned color register accuracy is carried out, for example, in a printing press designed as a rotary printing press, in particular a printing press for security printing, wherein a substrate 26 designed, for example, as a printing material web or a printing sheet is guided via a cylinder designed, for example, as a finishing cylinder 42, wherein the printing ink relating to the relevant printed image 27 is applied to the substrate 26 by continuous overprinting, or in a preferred embodiment, the printing ink relating to the relevant printed image 27 is collected, for example, on a transfer cylinder 43 and discharged from the transfer cylinder 43 together onto the substrate 26 guided by the finishing cylinder 42. The substrate 26 is designed, for example, as a printing material web in the form of a polymer film or a printing sheet made of paper.

[0070] At least two plate cylinders 44 are in contact with or at least can be in contact with the circumference of the transfer cylinder 43, and each of these plate cylinders 44 transfers one of the printing inks of the printing image 27 involved to the transfer cylinder 43. The rotation direction of the pressing cylinder 42, the transfer cylinder 43 and the plate cylinder 44 is respectively Figure 7 The direction of rotation is indicated by arrows in the figure. It is known to those skilled in the art that each plate cylinder 44 is provided with a Figure 7 In the preferred embodiment, the printing inks transferred by the plate cylinder 44 abutting against the transfer cylinder 43 differ in their color tones.

[0071] Downstream of the transfer point, where the transfer cylinder 43 prints the printing ink collected thereon onto the substrate 26 guided by the pressing cylinder 42 to produce the printed image 27, a printing device is arranged on the same side of the substrate 26 as the printed image 27 generated at the transfer point, wherein the printing device overprints the printed image 27 at least partially with a layer 39 made of light-colored, preferably white ink. The printing device is preferably designed as at least one inkjet print head 46. In a preferred embodiment, the color tone of the ink printed by the relevant inkjet print head 46 is lighter than the corresponding color tone of the printing ink applied to the substrate 26 by the transfer cylinder 43.

[0072] Preferably, an embossing device 47 is also provided in the printing press, with which a micro-optical structure 03 consisting of micro-lenses 11 is formed on the substrate 26. The embossing device 47 can then be arranged upstream of the closing cylinder 42 in the printing press. However, in a particularly advantageous embodiment, the closing cylinder 42 has the embossing device 47 on its circumference, wherein the micro-optical structure 03 consisting of micro-lenses 11 is formed with the embossing device 47, and during rotation, the closing cylinder 42 is arranged on the substrate 26 guided by the closing cylinder 42. The micro-lenses 11, for example, made of synthetic material or resin, have a lens width 18 of, for example, less than 100 μm, preferably between 20 μm and 65 μm.

[0073] Thus, a printing press for producing a security document 02 is obtained, wherein a closing cylinder 42 for guiding a substrate 26 of the security document 02 and a transfer cylinder 43 cooperating with the closing cylinder 42 at a transfer location for printing a printed image 27 onto the substrate 26 are provided. The substrate 26 of the security document 02 has at least one transparent window 04, wherein a micro-optical structure 03 composed of micro-lenses 11 is arranged on one side of the substrate 26, at least in the region of the relevant transparent window 04. The closing cylinder 42 and the transfer cylinder 43 are arranged in cooperation with each other in such a way that during the printing process, the micro-optical structure 03 composed of micro-lenses 11 is arranged on one side of the substrate 26, at least in the region of the relevant transparent window 04, and at least one printed image 27 is arranged on the other side of the substrate 26 opposite to the micro-optical structure 03, at least in the region of the relevant transparent window 04. This arrangement of the micro-optical structure 03 made of micro-lenses 11 realized by the embossing device 47 and at least one printed image 27 generated by the embossing roller 42 and the transfer roller 43 in the area of ​​the transparent window 04 can be realized simultaneously at the aforementioned transfer position or at different positions and staggered in time in relation to the circumference of the embossing roller 42.

[0074] A printing unit is also provided in the printing press, wherein the printing unit applies a layer 39 that extends in a flat manner and covers the relevant printed image 27, at least on a section of the relevant printed image 27, on the side facing away from the micro-optical structure 03. The printing unit is arranged downstream after the transfer point, where the transfer cylinder 43 prints the printed image 27 on the substrate 26 guided by the pressing cylinder 42, and is arranged on the same side of the substrate 26 as the printed image 27 realized at the transfer point, and is designed according to the invention as at least one inkjet print head 46. In this case, in its preferred configuration, the relevant printed image 27 has a plurality of image elements 28a-28j of different tones in the form of dots or lines, wherein the image elements 28a-28j are each formed in a tones other than white, and the layer 39 formed by the at least one inkjet print head 46 is formed in a lighter tone than the tones other than white forming the relevant printed image 27.

[0075] Advantageously, in order to maintain a high register accuracy, the embossing cylinder 42 has an embossing device 47 on its circumference, wherein the embossing device 47 forms the micro-optical structure 03 consisting of micro-lenses 11 and is arranged in such a way that the embossing device forms the micro-optical structure 03 consisting of micro-lenses 11 on the substrate 26 guided by the embossing cylinder 42 during the rotation of the embossing cylinder 42, that is, during the ongoing printing process. The pixel size 38 or the line thickness 38 of the image elements 28a-28j of the relevant printed image 27 is preferably smaller than the lens width 18 of the micro-lenses 11 arranged in the micro-optical structure 03.

[0076] In a preferred design of the printing press, at least two plate rollers 44 are provided which are abutted against or at least capable of abutting against the circumference of a transfer roller 43, each of which transfers one of the printing inks relating to the associated printing image 27 to the transfer roller 43, wherein the transfer roller 43 collects these printing inks of different colors and transfers the printing inks collected on the transfer roller 43 together to a substrate 26 guided by a pressing roller 42.

[0077] Reference numerals list

[0078] 01Safety Elements

[0079] 02Security Documents

[0080] 03Optical imaging structure; micro-optical structure

[0081] 04 Window

[0082] 05-

[0083] 06 Notch

[0084] 07Broken Line

[0085] 08-

[0086] 09-

[0087] 10-

[0088] 11Microlens

[0089] 12Axis of symmetry; optical axis

[0090] 13 Convex envelope surface

[0091] 14 Beam

[0092] 15-

[0093] 16 edge points

[0094] 17 Edge Points

[0095] 18 lens width

[0096] 19 Main plane

[0097] 20-

[0098] 21Flat envelope surface

[0099] 22 focal length

[0100] 23 Focus

[0101] 24 focal planes

[0102] 25-

[0103] 26 Base material

[0104] 27 Printing

[0105] 28 Element (28a-28j)

[0106] 29 Material thickness; thickness

[0107] 30-

[0108] 31 Cutting plane

[0109] 32 cone; angular field

[0110] 33 First viewing angle

[0111] 34 Second viewing angle

[0112] 35-

[0113] 36 layers thickness

[0114] 37 Vertex

[0115] 38px size; line thickness

[0116] 39th floor

[0117] 40-

[0118] 41 Printing

[0119] 42 Pressing roller

[0120] 43 transfer roller

[0121] 44 Plate Cylinder

[0122] 45-

[0123] 46 inkjet print heads

[0124] 47 Imprinting device

Claims

1. A security document (02) having a transparent window (04) formed in its substrate (26), wherein: A micro-optical structure (03) consisting of micro-lenses (11) is arranged on one side of a substrate (26), at least in the region of a transparent window (04), and at least one first printed image (27) is arranged on the other side of the substrate (26) opposite to the micro-optical structure (03), at least in the region of the transparent window (04), wherein the respective first printed image (27) has a plurality of picture elements (28a-28j) in the form of a dot-shaped or line-shaped grid, wherein the pixel size (38) or the line thickness ( 38) are respectively designed to be smaller than the lens width (18) of the microlenses (11) arranged in the micro-optical structure (03), wherein a layer (39) extending in a planar manner and covering the corresponding first printed image (27) is arranged on at least a part of the corresponding first printed image (27) and on a side of the corresponding first printed image facing away from the micro-optical structure (03), wherein the layer covering the corresponding first printed image (27) is generated in an inkjet printing process, characterized in that the layer (39) is designed to have a wavelength of 380 nm. The invention discloses a layer (39) for covering a first printed image (27) and a micro-optical structure (03) for transmitting electromagnetic radiation in the range of 70 to 780 nm, wherein the transmittance of the electromagnetic radiation is in the range of 10% to 90%, and the transmittance is designed to gradually change on the two-dimensional surface extension of the layer (39) covering the corresponding first printed image (27), so that: at least one part of the layer (39) or some parts of the layer (39) are designed with a transmittance different from that of other parts of the layer (39), wherein a micro-optical structure (03) is arranged on the side of the layer (39) that partially covers the first printed image (27) facing away from the micro-optical structure (03) A second printed image (41) is provided, wherein the second printed image (41) is arranged on a layer (39) covering a portion of the first printed image (27) so that the second printed image (41) can overlap with the micro-optical structure (03) applied on the other side of the substrate (26) of the security document (02) after being folded at the fold line (07), so that the second printed image (41) or at least one information contained in the second printed image can be seen and / or can be identified when viewed from the direction of the micro-optical structure (03).

2. The security document (02) according to claim 1, characterized in that The image elements (28a-28j) of the corresponding first printed image (27) are formed in a color tone different from white, wherein the layer (39) covering the corresponding first printed image (27) is formed in a color tone lighter than at least one color tone different from white forming the corresponding first printed image (27).

3. The security document (02) according to claim 1 or 2, characterized in that The layer ( 39 ) is formed in a white tone.

4. The security document (02) according to claim 1 or 2, characterized in that A corresponding first printed image (27) arranged on the side of the substrate (26) opposite the micro-optical structure (03) is produced using a lithographic method.

5. The security document (02) according to claim 1 or 2, characterized in that A respective first printed image (27) arranged on the side of the substrate (26) opposite the micro-optical structure (03) consists of a plurality of superimposed or superimposed sub-printed images, each printed with a different printing ink.

6. The security document (02) according to claim 1 or 2, characterized in that The micro-optical structure (03) is designed as a lens array or a biconvex lens, wherein the lens array or the biconvex lens is respectively composed of plano-convex microlenses (11), wherein the plano-convex microlenses (11) are designed in a spherical or non-spherical manner in the case of the lens array, and are designed in an axially symmetrical manner in the case of the biconvex lens.

7. The security document (02) according to claim 1 or 2, characterized in that A plurality of image elements (28a-28j) of the corresponding first printed image (27) which are arranged below the micro-optical structure (03) in the viewing direction are designed to belong to different printed themes.

8. The security document (02) according to claim 1 or 2, characterized in that The respective first printed image ( 27 ) is designed to contain information that is directly recognizable to humans or to be designed to be only machine-readable.

9. The security document (02) according to claim 1 or 2, characterized in that The fold line (07) is arranged spaced apart from a layer (39) that partially covers the first printed image (27).

10. The security document (02) according to claim 1 or 2, characterized in that The substrate (26) is a fiber-containing printing material or a polymer film.

11. The security document (02) according to claim 1 or 2, characterized in that The security document (02) is designed as a banknote.

Images