DE102022111096B3 - Method of authenticating a security document - Google Patents

Abstract

The invention relates to a method for authenticating a security document, with the security document having a transparent window in its substrate, with a micro-optical structure consisting of microlenses being arranged on one side of the substrate at least in the area of the transparent window, partially or completely covering this window and with on the other side of this substrate outside and at a distance from the area of the transparent window, a print image is applied, this print image being applied to the substrate in a dot-shaped or line-shaped grid consisting of image elements, with a pixel size or a line thickness of the image elements of the print image applied to the substrate is made smaller than a lens width of the microlenses arranged in the micro-optical structure, with the substrate of this security document being folded at a fold line and the printed image applied outside and at a distance from the area of the transparent window with the micro-optical structure applied on the other side of the substrate of this security document in such a way This printed image or at least an item of information contained in it becomes visible and/or recognizable when viewed from the direction of the micro-optical structure by looking at this printed image.

Description

The invention relates to a method for authenticating a security document according to claim 1.

through the U.S. 2017/0 210 161 A1 discloses an improved polymeric sheet material for use in the manufacture of polymeric security documents, such as banknotes, made from a polymeric or polymeric substrate having a thickness greater than or equal to about 60 micrometers (µm) and one or more integrated optical security devices. projecting one or more synthetic images, wherein the one or more optical security devices are integrated into all or part of the substrate, the one or more integrated optical security devices leading to one or more clear windows and to one or more opaque areas aligned with the substrate and made up of an array of metallized hybrid refractive/reflective focusing elements disposed below a first array of icons on a top surface of the substrate and a second array of icons immediately below the first array of icons and the array of metallized hybrid refractive/reflective focusing elements are located on a lower surface of the substrate, with one or more opaque areas located on the second array of icons, one or more synthetic images projecting through the polymer sheet material in reflective and transmitted light wherein the one or more opaque areas allow for viewing of reflected light, and wherein the one or more clear windows allow for viewing of transmitted light that outperforms viewing of reflected light.

through the DE 11 2016 001 903 T5 discloses an optical device, preferably a security device for a security document, including a substrate having a first side and a second side, an array of microlenses located on the first side, and an array of microimages such that the microimages are viewed through the microlenses are viewable or can be made viewable, wherein the array of microlenses includes first and second microlenses and wherein the array of microimages includes first and second microimages, wherein the first microlenses and the first microimages are configured to provide a first visual effect and wherein the second Microlenses and the second microimages are configured to provide a second visual effect, and wherein the first microlenses have a different height relative to the substrate than the second microlenses.

through the U.S. 2012/0 001 411 A1 discloses a security document having a development frame associated with a combined image present on the document, or combination with a security document and another object, the security document having a development frame associated with a combined image on the other object, the combined Image and/or the development frame appear on an at least partially transparent area of the document, wherein an overlay of the development frame and the combined image can be effected by folding the document or by overlaying the document and the other object, the combined image having at least two interlaced images wherein the development frame, when at least partially superimposed on the combined image of the same document or of the different object, enables the successive observation of the interlaced images by a relative displacement of the development frame with respect to the combined image.

through the EP 2 493 700 A2 a method of manufacturing a security device is known, the method comprising: providing an array of lenticular focusing elements on one side of a transparent substrate; and providing a corresponding array of sets of image strips on the other side of the transparent substrate, the image strips and the focusing lenticular elements defining a lenticular device such that from different viewing directions a corresponding image strip from each set is viewed via respective focusing lenticular elements.

through the WO 2011/107 783 A1 discloses a security document comprising a document substrate having at least two transparent or translucent windows spaced from each other and a device comprising a transparent substrate carrying: i) a regular array of micro-focusing elements on a first surface, wherein the focusing elements define a focal plane; ii) a corresponding first array of micropixels of a first color and located in a plane substantially coincident with the focal plane of the focusing elements; and, iii) a corresponding second array of micropixels, in a different color from the first color and in a plane, which substantially coincides with the focal plane of the focusing elements, the pitches of the micro-focusing elements and the first and second arrays of micro-pixels and their relative positions being such that the array of micro-focusing elements cooperates with each of the first and second arrays of micro-pixels to generate respective enlarged versions of the micropixels of each array due to the moire effect; and wherein at least a portion of the first array of micropixels is not overlapped by the second and at least a portion of the second array of micropixels is not overlapped by the first; wherein the device is incorporated into or applied to the document substrate in alignment with the at least two windows, the device being registered with respect to the document substrate such that the enlarged version of the first micropixel array is visible through the first of the two windows and the enlarged version the second micropixel array is visible through the second of the two windows, the junction between the two micropixel arrays being obscured by the document substrate between the two windows.

through the DE 11 2010 000 957 T5 discloses a lens array for imaging a plurality of pixels in an object plane, the lens array including a plurality of microlenses formed in or on one side of a transparent or translucent material with the pixels arranged on the opposite side, the lens array having a gauge thickness corresponding to the distance from the apex of each microlens to the object plane, each microlens having a set of lens parameters, wherein the gauge thickness and/or at least one lens parameter are optimized such that each microlens has a focal spot size in the object plane substantially equal to the is the size of the picture elements in the object plane, or which deviates from the size of the picture elements by a predetermined amount. In this case, the measurement thickness of the lens array is preferably less than the focal length of all microlenses. The picture elements can e.g. B. take the form of points or lines. The lens array of DE 11 2010 000 957 T5 is designed in such a way that in a sectional plane lying in a cone or angular field of the light incident on the microlens in question in the direction of the picture elements parallel to the main plane of the microlens in question, only one of the picture elements arranged next to one another is always arranged, whereby for one the printed image is below a certain Viewing angle viewing viewer at a given time is always only a single frame perceptible.

The invention is based on the object of creating a method for authenticating a security document.

The object is achieved by a method for authenticating a security document having the features of claim 1. The dependent claims show advantageous refinements and/or developments of the solution found.

• 1 ein Sicherheitsdokument mit einem eine optisch abbildende Struktur aufweisenden Sicherheitselement;
• 2 eine stark vergrößerte Schnittdarstellung einer Anordnung aufweisend mindestens ein Druckbild und eine in eine optisch abbildende Struktur eingebundene einzelne plankonvexe Mikrolinse mit einem Lichteinfall aus einem ersten Betrachtungswinkel;
• 3 die Anordnung gemäß der 2 mit einem Lichteinfall aus einem zweiten Betrachtungswinkel;
• 4 ein Sicherheitsdokument mit Mitteln zur Selbstauthentifikation;
• 5 ein Sicherheitsdokument mit einer kontrastverstärkenden Rückseite;
• 6 ein Sicherheitsdokument mit einer kontrastverstärkenden Rückseite und mit Mitteln zur Selbstauthentifikation;
• 7 eine vereinfachte schematische Darstellung einer Druckmaschine zur Herstellung eines Sicherheitsdokuments insbesondere gemäß 5 oder 6.

An embodiment is shown in the drawings. Show it:

• 1 a security document with a security element having an optically imaging structure;
• 2 a greatly enlarged sectional view of an arrangement having at least one printed image and one integrated into an optically imaging structure individual plano-convex microlens with a light incidence from a first viewing angle;
• 3 the arrangement according to the 2 with a light incidence from a second viewing angle;
• 4 a security document with means for self-authentication;
• 5 a security document with a contrast-enhancing reverse side;
• 6 a security document with a contrast-enhancing reverse side and with means for self-authentication;
• 7 a simplified schematic representation of a printing machine for producing a security document, in particular according to FIG 5 or 6 .

In optics, the term "lens" refers to a component that is transparent to light and has at least one light-refracting surface arranged in the beam path of the light. The term light is understood here to mean the part of the electromagnetic radiation that is visible to the human eye. In the electromagnetic spectrum, light has wavelengths from about 380 nm (violet) to 780 nm (red). The following is based on converging lenses, ie lenses that focus incident light, in particular lenses of plano-convex design. Preferred designs are, on the one hand, rotationally symmetrical, spherical or aspherical lenses and, on the other hand, axisymmetric, rod-shaped lenses, with the respective axis of symmetry of the lens in question and its optical axis each running congruently. The optical axis is thus one that generally runs through the center of curvature of a convex lens surface Straight. In the case of a flat lens surface, the optical axis is perpendicular to it. The curvature of a refractive z. B. convex surface is indicated by its radius of curvature, where the radius of curvature has its origin on the optical axis. A plane lens surface is defined by an infinitely large radius of curvature.

Rod-shaped lenses are designed in the form of either a right circular cylinder or an elliptical cylinder that is bisected in each case according to their rod length, with the respective axis of symmetry of such a lens extending orthogonally to its respective rod length. In the case of a spherical lens, the light-refracting surface is designed as a surface section of a sphere, e.g. B. in the form of a spherical cap. An aspherically designed lens has at least one light-refracting surface that deviates from the spherical or planar shape. The shape of rotationally symmetrical aspherical surfaces is usually specified as a conic section (circle, ellipse, parabola, hyperbola) plus a correction polynomial for higher-order deformations.

A lens has two surfaces intersected by the beam path of the light, so-called enveloping surfaces, whereby with regard to light bundling, it applies by definition that the light enters a plano-convex converging lens at its convex curved enveloping surface and the light exits from this lens at its planar enveloping surface. The enveloping surfaces are in each case boundary surfaces between different media in which the light propagates. One of these media is represented by the material, i. H. formed the material of the lens in question. At least one other medium is the i. i.e. R. Air-filled space in which the lens in question is located. Since at least two of the media arranged in the beam path of the light have at least their respective optical material properties that differ from one another, the light is refracted at the interface between these adjoining media. Thus, light is refracted on at least one of the enveloping surfaces of the respective lens, in particular on its curved enveloping surface. The optical material property related to the refraction of light is expressed by the respective refractive index of the medium in question. The refractive index is a dimensionless physical quantity that indicates by what factor the wavelength and phase velocity of light in the medium in question are smaller than in a vacuum. Of two media that share an interface and have different refractive indices, the medium with the higher refractive index is said to be optically denser. The Abbe number, also known as Abbe's number, is a dimensionless quantity for characterizing the optical dispersive properties of a lens and indicates how strongly its refractive index changes with the light wavelength. The property of a lens to be able to generate an optical image of an object viewed through the lens in question depends on the refractive index of the material of the lens in question and on the shape of the enveloping surfaces forming interfaces between different media.

A plane arranged orthogonally to the axis of symmetry of the relevant lens in this component is referred to as the main plane of a lens. In the case of a thin lens, in which its greatest extent lies along the axis of symmetry, i. H. the thickness of the lens is to be regarded as very small compared to the radius of curvature of its convex envelope surface, because the radius of curvature of the convex envelope surface z. B. is at least five times greater than this thickness, only a single main plane can be used as a basis for considering properties of the lens in question with usually sufficient accuracy. In the case of a plano-convex lens, this principal plane coincides with the plane lens surface. The focal length of a lens is the distance between the main plane of the lens in question and its focus (focal point), whereby the focus of a lens is to be understood here as an intersection point of light rays bundled by the lens and incident in parallel on this lens. In this case, the light beams incident parallel to the lens do not necessarily impinge parallel to its optical axis, but rather at an arbitrary, in particular acute, angle of incidence with respect to the main plane of the lens in question. A plane that is orthogonal to the optical axis in the focus is called the focal plane.

The enveloping surface of the lens in question, which serves to allow light to enter, has two opposite, e.g. B. lying in the main plane of this lens edge points, the distance between these two edge points determines a width of the lens in question (= lens width). The aperture or opening width of a lens refers to its free opening or its diameter through which light rays can be received unhindered and corresponds at most to the lens width. The point that lies at the point of intersection of the optical axis with the enveloping surface of the lens in question, which serves to allow the light to enter, is called the vertex. The vertex is located furthest from the focus of this lens on the enveloping surface used for light entry.

A rotationally symmetrical spherical or aspheric lens focuses light incident on it in a cone or cone, where the diameter of the base of this cone or cone corresponds at most to the lens width and the height perpendicular to the base of this cone or cone corresponds to the focal length of the lens in question. An axisymmetric rod-shaped lens focuses light incident on it in an acute angular field, the origin of the angular field being in the focus of this lens. The numerical aperture describes the ability of a lens to focus light. It determines the minimum size of the light spot that can be generated in its focus and is therefore an important variable that limits the resolution.

Several rotationally symmetrical spherical or aspherical lenses, which are arranged in a preferably uniform lattice consisting of either square or hexagonal lattice cells, in particular without gaps and without overlapping, form a lens group, which is also referred to as a lens array. A plurality of rod-shaped lenses, each of which is axially symmetrical and which is also preferably lined up in a row orthogonally to its rod length without any gaps or overlaps, form a lens raster, which is also referred to as a lenticular lens. A plurality of lenses arranged in a lattice-like lens group and/or a plurality of lenses arranged in a lens grid form in their respective combination an optically imaging structure in the form of a geometric figure extending over a flat or curved surface. The surface of the optically imaging structure can have any contour, e.g. B. rectangular, round, oval or polygonal. In geometry, a geometric figure is understood as a set of points. With respect to the optically imaging structure, a lens is arranged at least on a subset of the points forming the geometric figure.

In an optically imaging structure, only one or more lattice-shaped lens groups or only one or more lenses arranged in a lens raster can be arranged as well as these two lens arrangements mixed together with the other lens arrangement, so that in the same optically imaging structure both lattice-shaped lens groups and lenses arranged in a lenticular grid are arranged together. In this case, in the relevant optically imaging structure trained lenticular grid z. B. also each have a different orientation, the respective orientation of the lens grid in question is determined by the respective direction of the rod length of the lenses involved in the structure of the lens grid in question.

A microlens is a miniaturized form of a conventional lens. The term microlens should be understood here to mean a lens whose lens width is less than 100 μm and is preferably in the range between 20 μm and 65 μm. Microlenses have a focal length of less than e.g. B. 100 microns, preferably a maximum of 95 microns. Microlenses can now be produced industrially. Microlenses made of a plastic or resin can e.g. B. using a (injection) casting process or (injection) embossing process or printing process. Optically imaging structures consisting of microlenses are also referred to as micro-optical structures.

If an optically imaging structure formed in particular from microlenses is or is arranged in combination with a preferably two-dimensional printed image, in that this optically imaging structure z. B. is or is applied to a substrate having the printed image, various effects can be produced for an observer viewing the printed image through the optically imaging structure. Thus, an arrangement consisting of at least one printed image and at least one optically imaging structure, e.g. B. so-called changing images or shaky images (flips) and / or spatial, d. H. generate three-dimensional effects and/or morphing effects and/or zoom effects and/or animations. These effects can be perceived by a viewer without optical aids if he/she views the printed image alternately from different viewing angles. The perception presented to the viewer through different viewing angles is also called a lenticular image.

The I. i.e. R. flat print image is on the preferably two-dimensional substrate z. B. preferably formed in an industrial manufacturing process with a printing press. The substrate is z. B. formed a substrate web or as a printed sheet. The print image is z. B. applied to the substrate in a punctiform or linear grid. The print image is therefore z. B. from several, in particular a large number of pixels and / or lines. A pixel size or line thickness is in a range of less than 100 μm, preferably less than 50 μm, in particular less than 20 μm, e.g. B. in the range of about 5 microns to 10 microns. In the following it is assumed that the pixel size of pixels and/or the line thickness of lines that are involved in the formation of a print image used together with an optically imaging structure, e.g. B. are each at most as large, preferably smaller, in particular less than half as large as the respective lens width of the lenses involved in the construction of the relevant optically imaging structure.

In optics, resolving power is the distinguishability of fine structures, i.e. the minimum distance that z. B. must have two pixels or two lines from each other in order to be able to perceive them as separate pixels or lines. The resolving power of the naked human eye varies from person to person. At a distance of 25 cm, normal-sighted adults can usually still distinguish structures at a distance of 150 µm. This corresponds to a viewing angle of about 2 minutes of arc, which is referred to as angular resolving power. In the case of weak contrasts, the visual acuity of the human eye decreases noticeably, with visual acuity being the reciprocal of the resolving power. The lens width of a microlens is therefore usually less than the resolving power of the naked eye of a normal-sighted adult.

To produce a colorful printed image, the substrate is or is printed with several printing colors, e.g. For example, the printing colors red, green, blue and optionally the printing color black, referred to as primary colors, are formed on the substrate. As a rule, a print image consists of an arrangement of a plurality of small-area image elements arranged at different positions of the print image in question, with each image element preferably having a plurality of pixels or lines and i. i.e. R. extends over a length of less than 100 microns. Each picture element or a group of neighboring picture elements forms e.g. B. an object to be viewed through the lens. The individual picture elements are in a print image i. i.e. R. arranged to form a print motif that determines the informational content of a print image. Due to its limited i. i.e. R. insufficient resolving power, individual picture elements used in connection with a microlens are normally not singularly perceptible to the naked human eye. A color impression of the printed image or at least a part of this printed image perceived by a person is created by an additive color mixing taking place in the eye and brain of the viewer from pixels and/or lines printed in different printing colors in the relevant picture elements. An overlay of two primary colors results in the color impressions of yellow, cyan and magenta, which are referred to as secondary colors. An overlay of all three primary colors results in the color impression of white. A color register, i. H. a passport, d. H. an accuracy of fit of pixels and/or lines of different printing inks in their relative arrangement to one another is less than 20 μm, preferably less than 10 μm, and is in particular in the range of about 5 μm in the exemplary embodiments of the invention considered here.

The optically imaging structure provided in connection with the exemplary embodiments of the invention considered here is preferably arranged in combination with pixels and/or lines of different printing colors. The print image is or is preferably produced as or by superimposing several partial print images, with several or preferably each of the partial print images z. B. is printed in a different ink or is. The superimposition can be carried out by successive overprinting on the substrate or preferably by collecting the partial print images on a printing element, e.g. B. on a cylinder, and a simultaneous delivery to the substrate effected. The partial print images in turn each consist of pixels and/or lines, with the pixel size of these pixels and/or the line thickness of the relevant lines being in the micrometer range, e.g. B. in the range of less than 20 microns. In the case of an observer looking at the print image, the several partial print images involved in this print image, e.g. B. to an overall color impression.

An arrangement consisting of at least one printed image and at least one optically imaging structure allows a viewer looking at the printed image to perceive several different individual images from different viewing angles, with a sequence of individual images in the perception of the viewer being an alternating image or a shaky image (flip) and/or a spatial image , i.e. H. three-dimensional effect and/or a morphing effect and/or a zoom effect and/or an animation. Each of these individual images is also referred to as a frame. The individual images that can be perceived by the viewer from a specific viewing angle are created by a selection, determined by the optically imaging structure, from the set of partial print images that can be perceived at the respective positions of the microlenses on the basis of the at least one image element or image elements there, with the on one position of the print image related overall color impression is created by superimposing all of the partial print images that are present and perceptible at this position. The optically imaging structure arranged in combination with a printed image is accordingly an optical masking of the sub-printed images which are arranged in congruence with the surface of the optically imaging structure and are involved in the relevant printed image.

In order to allow a viewer looking at the printed image to be able to perceive several frames at the same time from a specific viewing angle, in order to B. to realize more complex and / or differentiated animations, z. B. having an arrangement a printed image and an optically imaging structure consisting of several plano-convex microlenses is used, in which several, preferably more than three, in particular between five and ten image elements are arranged next to one another under at least one microlens of the relevant optically imaging structure, these image elements between the extent of the lens width of the microlens in question and its focus are arranged in a cutting plane parallel to the main plane of the microlens in question, the cutting plane being arranged to intersect a cone or an angular field of the light incident through the lens width of the microlens in question in the direction of the picture elements arranged next to one another, wherein in the Cutting plane within the cone or the angular field at the same time several different picture elements are arranged in a row.

This results in an arrangement having a printed image and an optically imaging structure consisting of a plurality of plano-convex microlenses, each of these microlenses having a lens width of preferably less than 100 µm lengthwise to the printed image, the printed image having a large number of image elements, with at least one of the Microlenses of the optically imaging structure in question are arranged in each case a plurality of picture elements, with these several picture elements arranged under at least one of the microlenses of the optically imaging structure in question being arranged next to one another along the lens width and each extending in the direction of the lens width over a shorter length than the lens width in question between the extension of the lens width of the microlens in question and its focus in a section plane parallel to the main plane of the microlens in question lying in the cone or in the angular field of the light incident through the lens width of the microlens in question in the direction of the picture elements arranged next to one another, preferably at least at the same time three, in particular more than three different image elements are arranged in a row. With this arrangement, a viewer looking at the printed image can perceive several frames at the same time from a specific viewing angle, which allows for complex and/or differentiated animations as well as gradual color transitions in the case of correspondingly colored image elements and/or gradual frame transitions in the case of different print motifs formed from the image elements .

The substrate is z. B. a fiber-containing printing material, in particular paper, or a film, preferably a polymer film. The substrate can be opaque or transparent. The substrate can be single-layer or multi-layer, in particular multi-layer in sections. Different layers of a multilayer substrate can be made of different materials, e.g. B. a layer of paper and another layer of a polymer film. The substrate or at least one respective layer of this substrate has a material thickness, i. H. thickness z. B. less than 100 microns, preferably less than 50 microns, especially about 25 microns. A printed image formed on the substrate has a layer thickness z. B. less than 10 microns, preferably less than 5 microns, especially in the range of 1 micron to 2 microns. The substrate can be printed on one or both sides.

In the preferred embodiment of the invention, the arrangement of printed image and optically imaging structure is part of a security element or a document, in particular a security document. These documents include, for example, banknotes, credit cards, checks, securities, stock certificates, passports, ID cards, driver's licenses, title deeds, travel documents such as airline or train tickets, admission tickets, student receipts and other official or regulatory documents such as birth, death or marriage certificates. This list is only exemplary and by no means exhaustive. However, it is preferably banknotes.

1 shows an example of a document 02, in particular a security document 02, on or in which at least one security element 01 is arranged. The document 02 and/or the security element 01 in question has at least one optically imaging structure 03 over part or all of the area, with the respective optically imaging structure 03 preferably being embodied as a micro-optical structure 03 made of microlenses 11. The relevant optically imaging structure 03 is arranged in such a way that it B. at least partially covers a printed image 27 formed or applied to the document 02.

2 shows an example in particular as a section from the in the 1 security element 01 or document 02 shown in a greatly enlarged sectional view, an arrangement with a single plano-convex microlens 11, which is integrated into a group or into a grid of microlenses 11. The relevant microlens 11 has an axis of symmetry 12 which also forms the optical axis 12 of this microlens 11 at the same time. The microlens 11 can be rotationally symmetrical spherical or aspherical or it is z. B. axisymmetrically rod-shaped, with an axisymmetric rod-shaped microlens 11, the axis of symmetry 12 orthogonal to its rod length. The micro lens 11 is z. B. made of a transparent plastic or resin injection or casting or embossing or printing technology. The microlens 11 has a light entry serving convex envelope surface 13, where z. B. a bundle of parallel light rays 14 hits this enveloping surface 13 . The microlens 11 has axisymmetric to its optical axis 12, which runs through the vertex 37 of the convex envelope surface 13, two opposite edge points 16 delimiting the convex envelope surface 13; 17, the distance between these two edge points 16; 17 determines a width of this microlens 11 referred to as the lens width 18 . The lens width 18 of a microlens 11 is less than 100 μm. The two edge points 16; 17 of the convex enveloping surface 13 lie in a plane arranged orthogonally to the optical axis 12 of the relevant microlens 11, which is also referred to as the main plane 19 of this microlens 11. In the in the 2 illustrated embodiment, the main plane 19 forms a planar enveloping surface 21 of the microlens 11 in question. A distance between the main plane 19 of the microlens 11 and its focus 23 (focal point) forms the focal length 22 of the microlens 11 in question, the focus 23 being an intersection of the bundled, in particular parallel to the microlens 11 incident light beams 14 is. The focal length 22 of a microlens 11 is less than 100 μm. A plane arranged orthogonally to the optical axis 12 in the focus 23 is called the focal plane 24.

In the in the 2 In the exemplary embodiment illustrated, the microlens 11 is part of a lens array or a lens grid in which a plurality of microlenses 11 are arranged in relation to a specific surface of any desired contour, preferably without gaps and without overlapping. The lens array or lens raster is arranged on a substrate 26, the substrate 26 z. B. as a fiber-containing printing material with a transparent window, in particular paper, or as a film, preferably as a transparent polymer film is formed. The substrate 26 has a material thickness 29 or thickness 29 z. B. less than 100 microns, preferably less than 50 microns, especially about 25 microns. 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 transparent at least in the area covered by the planar enveloping surface 21 of the respective microlens 11.

In the in the 2 illustrated embodiment is on the back of the substrate 26, ie on the side facing away from the microlens 11 side of this substrate 26, a printed image 27 small layer thickness 36 z. B. applied of less than 10 microns, this printed image 27 has a plurality of individual image elements 28 each different from one another. These individual picture elements 28 have a very small area and extend parallel to the lens width 18 over only a few micrometers, e.g. B. over a maximum of 10 microns. It is therefore possible to use several, e.g. B. ten such picture elements 28a to 28j in the area covered by the planar envelope surface 21 of the microlens 11 z. B. lined up next to each other. At least one of these picture elements 28a to 28j preferably has picture dots and/or lines printed in different inks, in particular depending on the number of z. B. adjacently arranged image elements 28a to 28j whose respective pixels have a pixel size 38 and/or whose lines have a line width 38 in the range of a few micrometers, preferably in the range of less than 20 μm. The print image 27 preferably consists of a superimposed print or a superimposition of a plurality of partial print images each printed in different inks. The picture elements 28a to 28j arranged next to one another in the area covered by the planar enveloping surface 21 of the microlens 11, ie under the relevant microlens 21, preferably each belong to different print motifs.

The under the relevant microlens 11 z. B. Image elements 28a to 28j arranged side by side are advantageously arranged closer to microlens 11 than its focus 23. These image elements 28a to 28j are preferably arranged between the microlens 11 in question and its focus 23 in a section plane 31 that is parallel to the main plane 19 of the microlens 11 in question , Wherein the cutting plane 31 has a cone 32 or an angular field 32 of the respective through the lens width 18 of the microlens 11 in question in the direction of z. B. juxtaposed image elements 28a to 28j of incident light is arranged intersecting, wherein in the cutting plane 31 within the cone 32 or the angular field 32 preferably several of the image elements 28a to 28j are arranged in a row at the same time. In the in the 2 illustrated embodiment are within the cone 32 or the angular field 32 at the same time z. B. five image elements 28c to 28g are arranged in a row, whereas the remaining image elements 28a, 28b and 28h to 28j arranged in the area covered by the planar enveloping surface 21 of the microlens 11 are visible to an observer looking at the printed image 27 under a corresponding light beam 14 e.g. B. acute first viewing angle 33 are not perceptible. If, for a viewer looking at the printed image 27, the viewing angle becomes different from the first viewing angle 33, e.g. B. obtuse second viewing angle 34 is changed, change for him also the picture elements 28a to 28j which he can perceive. This is in the 3 shown, the same arrangement with a printed image 27 and an optically imaging structure 03 consisting of a plurality of plano-convex microlenses 11 as the 2 having. Due to the second viewing angle 34, which is different from the first viewing angle 33, in the 3 illustrated embodiment for a viewer looking at the printed image 27 only the image elements 28d to 28h perceptible, but not the others.

As mentioned, those in the 2 and 3 picture elements 28a to 28j shown in the area covered by the planar enveloping surface 21 of an individual microlens 11 are formed by picture elements and/or lines preferably each printed in different inks. As a rule, the respective pixel size 38 of the relevant pixels and/or the line width 38 of the relevant lines is in each case significantly smaller than the lens width 18 of the relevant 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 form the print image 27 containing these image elements 28a to 28j in a machine-readable manner, at least one of these image elements 28a to 28j has image points and/or lines, in the printing of which special printing fluids, in particular inks, are used which, in terms of their optical properties, differ from conventional printing fluids, deviate in particular from usual printing colors or inks. These special pressure fluids are z. B. inks that are not visible to the naked human eye of a normal-sighted observer without an excitation lying outside the electromagnetic spectrum visible to the human eye, in particular an ink absorbing infrared radiation or an ink reflecting infrared radiation or an ink converting infrared radiation into the visible ink or an ultraviolet ray fluorescent ink or a magnetic ink. These inks, which are particularly invisible under daylight conditions, can be perceived in different hues like the other printing inks, e.g. B. in the color ranges blue, green or red. This excitation is preferably an electromagnetic or magnetic excitation.

The term ink is understood here to mean an intensely colored and coloring liquid, which usually consists of a solution or dispersions of colorants in water or other solvents, these solvents containing little or no binder in the case of inks designed as an ink. Colorants are coloring substances, e.g. B. pigments and dyes, which can be produced inorganically or organically, naturally or synthetically. In contrast, printing inks are colorant-containing mixtures that are applied to a substrate, i. H. be transferred to a substrate. Printing inks contain inorganic and organic pigments, e.g. B. titanium dioxide as a white pigment or carbon black as a black pigment, and binders that encapsulate the pigments. Both conventional inks and inks, including inks invisible to the human eye under daylight conditions, can be subsumed under the term printing fluid.

The aforementioned infrared radiation (IR) responsive special inks are e.g. B. used in connection with electromagnetic radiation from the near infrared range (NIR), whereby a radiation with a wavelength in the range between 780 nm and 2000 nm is preferably used, in particular in the range between 780 nm and 1200 nm. NIR) reactive ink contains e.g. B. inorganic i. i.e. R. pigment-shaped luminophores that emit radiation in the visible spectral range and/or infrared range (NIR) after absorbing energy. Ink that converts infrared radiation into visible light contains so-called anti-Stokes pigments.

Ultraviolet radiation, or UV for short, is electromagnetic radiation that is invisible to the human eye and has wavelengths that are shorter than visible light. According to a widely accepted classification, the spectrum in the ultraviolet ranges from 100 nm to 380 nm, i. H. from the short-wave range to the limit of visible light. An ink that fluoresces ultraviolet radiation has fluorescent color pigments that glow intensely under ultraviolet radiation and, if necessary, evaluate the ultraviolet rays of daylight.

A magnetic ink is understood as meaning an ink to which iron oxide particles have been added in particular. These particles can be magnetized by an external magnetic field, which is different from the earth's magnetic field, with respect to the relevant arrangement comprising the substrate 26 and the optically imaging structure 03, and can thus be magneto-optically analyzed and read out.

An arrangement that is advantageous in terms of machine readability, having a printed image 27 applied to a substrate 26 and an optically imaging structure 03 covering at least parts of the printed image 27, provides that the optically imaging structure 03 has a group or a grid of a plurality of plano-convex microlenses 11, with the planar envelope surface 21 of the micro lenses 11 the sub strata 26, wherein the printed image 27 arranged on the substrate 26 is preferably arranged on its side facing the optically imaging structure 03 and has at least one pixel 28a to 28j with at least one pixel and/or a line, this pixel and/or this line is typographically formed by a printing fluid, the printing fluid only being visible to the human eye as a result of an excitation lying outside the electromagnetic spectrum visible to the human eye. This printing fluid is preferably formed as an infrared ray absorbing ink, or an infrared ray reflecting ink, or an infrared ray-visible converting ink, or an ultraviolet ray fluorescent ink, or a magnetic ink. The relevant at least one image element 28a to 28j of the machine-readable printed image 27 is thus an integral part of the relevant arrangement, e.g. g. on a security element 01 or a document 02, in particular on a security document 02. The excitation of the printing fluid, which lies outside the electromagnetic spectrum visible to the human eye, takes place with reference to the optically imaging structure 03 covering at least parts of the printed image 27 on the front side, i.e. on the respective convex enveloping surface 13 of the microlenses 11, if this excitation is designed to act through the optically imaging structure 03, or directed at the rear, i.e. on the substrate side or towards the respective planar enveloping surface 21 of the microlenses 11, if the optically imaging structure 03 blocks this excitation is trained.

If it is provided that the pressure fluid visible to the human eye only as a result of an excitation lying outside of the electromagnetic spectrum visible to the human eye should not interact with the microlenses 11 of the optically imaging structure 03, then in such an arrangement the respective pixel size 38 of the relevant pixels and/or the line thickness 38 of the relevant lines z. B. respectively larger than the lens width 18 of the microlens 11 in question.

Furthermore, it can be provided that in the relevant arrangement of substrate 26 and optically imaging structure 03 at a plurality of individual positions in the group having a plurality of plano-convex microlenses 11 or in the grid having a plurality of plano-convex microlenses 11 of the respective optically imaging structure 03, the respective microlens 11 remains undeveloped and at least one pixel 28a to 28j of the printed image 27 with at least one pixel and/or a line is arranged at the defect in question, with this pixel and/or this line being typographically through the visible only as a result of the outside of the visible to the human eye Electromagnetic spectrum lying excitation visible to the human eye pressure fluid is formed. The pressure fluid, which is not visible to the human eye under normal conditions, is applied or arranged at selected flaws in the respective optically imaging structure 03.

As mentioned, the arrangement of substrate 26 and optically imaging structure 03 can have a printed image 27, which allows a normal-sighted observer looking at the printed image 27 through the optically imaging structure 03 with the naked eye to perceive a number of different individual images from different viewing angles, with a sequence of individual images in the perception of the viewer, a changing image or flickering image (flip) and/or a spatial, d. H. three-dimensional effect and/or a morphing effect and/or a zoom effect and/or an animation. These different individual images are also referred to as frames. These aforementioned effects are based on a plurality of partial print images, from which the relevant at least one print image 27 is composed. In order to form an arrangement of substrate 26 and optically imaging structure 03 with at least one machine-readable printed image 27, the relevant printed image 27 has a plurality of partial printed images, at least in the area covered by the optically imaging structure 03. At least one partial print image of these partial print images has image elements 28a to 28j with at least one pixel and/or one line, with the relevant pixel and/or the relevant line being printed by the excitation lying outside of the electromagnetic spectrum visible to the human eye pressure fluid visible to the human eye is formed. In an alternative or additional embodiment, it can be provided that at least one image element 28a to 28j of at least one partial print image of the print image 27 that is to be machine-readable and has a plurality of partial print images is formed by a mixture, with this mixture comprising a printing fluid that is visible to the human eye, particularly under daylight conditions, and a has pressure fluid visible to the human eye due to the excitation lying outside of the electromagnetic spectrum visible to the human eye.

Furthermore, to form an arrangement with at least one machine-readable printed image 27, it can be provided that in this arrangement having a substrate 26 having the printed image 27 and a structure 03 optically imaging this printed image 27 in a first of the optically image the area covered by structure 03, the image elements 28a to 28j of printed image 27 arranged therein, each by a printing fluid that is visible to the human eye, particularly under daylight conditions, and in a second area covered by the optically imaging structure 03, the image elements 28a to 28j of printed image 27 arranged therein are formed by a pressure fluid visible to the human eye only as a result of the excitation lying outside the electromagnetic spectrum visible to the human eye.

Irrespective of the particular design of the substrate 26 and/or the particular design of the optically imaging structure 03 formed thereon and/or the printing fluid used to form at least one printed image 27, whether a printing fluid that is visible to the human eye, particularly under daylight conditions, or whether it is only a result the excitation lying outside of the electromagnetic spectrum visible to the human eye is used, or whether both aforementioned types of printing fluid are used together to create the same printed image 27 to form a security element 01 or a security document 02, it can be provided what is described below.

4 shows an example of a security document 02, e.g. B. a banknote, the substrate 26 z. B. consists 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, there is a micro-optical structure 03 that partially or completely covers this window 04. This micro-optical structure 03 is designed as a lens array or as a lenticular, each of which consists of plano-convex micro-lenses 11 . In the case of a lens array, these microlenses 11 are rotationally symmetrical spherical or aspherical and in the case of a lenticular z. B. axially symmetrical rod-shaped. Outside and at a distance from the area of the transparent window 04, a printed image 27 is formed or applied on the other side of this security document 02, i.e. on the side of the security document 02 that does not have the aforementioned lens array or lenticular, this printed image 27 being printing fluid visible under daylight conditions or by printing fluid visible to the human eye only as a result of excitation lying outside of the electromagnetic spectrum visible to the human eye. The printed image 27 in question can contain information that is immediately recognizable to humans or can only be designed to be machine-readable. This printed image 27 is in a z. B. punctiform or linear grid consisting of picture elements 28a to 28j applied to the substrate 26 and preferably in an industrial printing process z. B. created in an offset printing process. A pixel size 38 or a line thickness 38 of the picture elements 28a to 28j of the printed image 27 applied to the substrate 26 is formed smaller than a lens width 18 of the microlenses 11 arranged in the lens array or lenticular and is therefore significantly less than 100 µm, preferably around 20 µm or fewer. If the window 04 that is partially or completely covered by the micro-optical structure 03 on this substrate 26 of the security document 02 is also on the back, i.e. on the side of the substrate 26 of the security document 02 facing away from the micro-optical structure 03, another printed image 27, preferably also created using an offset printing process , then this further printed image 27 arranged in the area of the transparent window 04 has at least one unprinted area in the area covered by the micro-optical structure 03, i.e. a recess 06, so that the recess 06 in question can be seen in the additional one arranged in the area of the window 04 Printed image 27 partially exposes the micro-optical structure 03 applied to the substrate 26 of this security document 02 and enables a view through the transparent window 04 onto the respective planar enveloping surface 21 of the plano-convex microlenses 11 arranged in the micro-optical structure 03.

A method for authenticating a security document 02 having a micro-optical structure 03 consists in that the substrate 26 of the security document 02—as in FIG 4 indicated by an arrow - folded along a fold line 07 that preferably runs through this security document 02, and as a result the printed image 27 formed or applied outside and at a distance from the area of the transparent window 04 with the micro-optical structure 03 applied to the other side of the substrate 26 of this security document 02, or at least is aligned or at least can be aligned with one of the recesses 06 partially exposing the micro-optical structure 03 in the printed image 27 arranged in the region of the window 04. The substrate 26 of the security document 02 can - as in the 4 indicated - at the fold line 07 z. B. be folded in about half, so that the part of the Substrate 26 is placed or at least can be placed on the other part of this substrate 26 that has the transparent window 04 and the micro-optical structure 03. As a result of the folding of the substrate 26 of the security document 02, the printed image 27 applied outside and at a distance from the area of the transparent window 04 is placed in the transparent window 04 of the substrate 26 of this security document 02 on the respective planar enveloping surface 21 of the plano-convex microlenses 11 arranged in the micro-optical structure 03 .

If necessary, by performing a relative movement between the micro-optical structure 03 and the printed image 27 that has been brought into alignment with this micro-optical structure 03 and formed or applied outside and at a distance from the area of the transparent window 04, or by performing a tilting movement of the entire security document 02 folded at the fold line 07 Printed image 27 or at least the information it contains is visible or recognizable when looking from the direction of the convex envelope surface 13 through the micro-optical structure 03 onto the relevant printed image 27 4 is indicated by way of example by a preferably human-readable "&" character.

The advantage of the solution found is that the security document 02 can be authenticated without using external means. The proposed method thus enables self-authentication of the security document 02 in question solely using means that the security document 02 in question has itself. The authentication proposed here is therefore proof that can be carried out anywhere and at any time that the security document 02 in question is an original, in particular a genuine bank note.

It was found that a printed image 27 in the area of the transparent window 04 on the back of the substrate 26, i. H. on the side of this substrate 26 facing away from the micro-optical structure 03 with an i. i.e. R. visible pressure fluid has been created, especially under low light, z. g. dim lighting conditions, when viewed from the direction of the convex enveloping surface 13 through the micro-optical structure 03 in question and onto the printed image 27 in question, is sometimes not sufficiently recognizable.

In order to improve the perceptibility of such a printed image 27, in particular for the human eye, it is proposed that the printed image 27 created in the region of the transparent window 04 on the rear side of the substrate 26 be overprinted with a printing fluid that has a lighter shade than the shade of the color used to create it of the relevant printed image 27 used printing fluid. If the print image 27 applied to the back of the substrate 26 in the area of the transparent window 04 has been created from a plurality of printing fluids of different color tones, a printing fluid that has a lighter color tone than the lightest color tone of the one used for creation is used to overprint this print image 27 created in this way of the relevant printed image 27 used printing fluid. The printed image 27 applied to the back of the substrate 26 in the region of the transparent window 04 is preferably at least partially overprinted with a layer 39 of white ink. This layer 39 forms an extensive cover layer consisting of light, particularly white ink for the printed image 27 applied to the back of the substrate 26 in the region of the transparent window 04. This cover layer can be opaque, i. H. opaque to electromagnetic radiation with a wavelength in the range from about 380 nm (violet) to 780 nm (red), d. H. opaque or partially transparent to electromagnetic radiation with a wavelength in the range from about 380 nm (violet) to 780 nm (red). The partial transparency can vary gradually over the two-dimensional areal extent of the cover layer, so that some areas of the cover layer are more transparent than other areas of this cover layer. A degree of transparency for incident light may range preferably between 10% and 90%.

It follows consequently - as in the 5 shown by way of example - a security document 02 with a transparent window 04 formed in its substrate 26, with a micro-optical structure 03 consisting of micro-lenses 11 on one side of the substrate 26, at least in the region of the transparent window 04, and on the other side of the micro-optical structure 03, opposite this Substrate 26 at least one printed image 27 are arranged. The print image 27 in question has a plurality of image elements 28a to 28j in a dot-shaped or line-shaped grid, these image elements 28a to 28j being embodied in a hue different from white. A pixel size 38 or a line width 38 of these image elements 28a to 28j is in each case smaller than a lens width 18 of the microlenses 11 arranged in the micro-optical structure 03. To enhance contrast, it is now provided that at least on a partial area, i.e. on a section of the printed image in question 27 on whose side facing away from the micro-optical structure 03 there is an extensive layer 39 covering the printed image 27 in question, this layer 39 being made of a lighter color tone consists of the at least one color tone different from white, of which the print image 27 in question consists. This layer 39 is preferably embodied in the color white. As mentioned above, the layer 39 covering the printed image 27 in question can be designed to be opaque to electromagnetic radiation with a wavelength in the range from 380 nm to 780 nm or this layer 39 is for electromagnetic radiation with a wavelength in the range from 380 nm to 780 nm nm formed transparent, with a degree of transparency for this electromagnetic radiation in the range z. B. is between 10% and 90%. In addition, the transparency over the two-dimensional areal extent of the layer 39 covering the printed image 27 in question can be designed to vary gradually, so that some places in this layer 39 have a different degree of transparency than other places in this layer 39. As a result, certain image elements 28a to 28j of the printed image 27 in question are emphasized by their improved perceptibility to the human eye, whereas other image elements 28a to 28j of the printed image 27 in question remain deliberately weaker in their perceptibility. In the preferred embodiment, the layer 39 covering the printed image 27 in question is or will be created in an inkjet printing process or in an offset printing process or in a screen printing process, whereas the printed image 27 in question arranged on the other side of the substrate 26 opposite the micro-optical structure 03 is created in an offset printing process is created.

By overprinting the printed image 27 applied in the region of the transparent window 04 on the back of the substrate 26, a contrast between the picture elements 28a to 28j contained in this printed image 27, i. H. whose pixels and/or lines, and whose respective immediate periphery is increased. The difference in brightness between adjacent light and dark areas in an image is generally referred to as contrast. By overprinting the print image 27 applied in the area of the transparent window 04 on the back of the substrate 26 with a layer 39 of a light, in particular white ink, the micro-optical structure 03 directs the print image 27 in question from the direction of the convex envelope surface 13 Viewing the contrast of several, preferably most, in particular of all image elements 28a to 28j of the print image 27 in question is increased, so that this print image 27 or at least the information contained in it, in particular under weak light, z. B. dim light conditions for the human eye is better recognizable or.

In a particularly advantageous embodiment of the invention, a security document 02 results with a contrast-enhancing layer 39 on the back of the substrate 26 together with means for self-authentication, as is shown by way of example in a sectional view in FIG 6 is shown and described below.

The 6 shows that in the 5 security document 02, shown as an example, with a transparent window 04 formed in its substrate 26, with a micro-optical structure 03 consisting of micro-lenses 11 on one side of the substrate 26, at least in the region of the transparent window 04, and on the other side of the substrate 26, opposite this micro-optical structure 03 a first printed image 27 are arranged. In this exemplary embodiment, too, this first printed image 27 has a plurality of picture elements 28a to 28j in a raster in the form of dots or lines, with these picture elements 28a to 28j preferably being formed in a hue different from white. A pixel size 38 or a line width 38 of these picture elements 28a to 28j is each smaller than a lens width 18 of the microlenses 11 arranged in the micro-optical structure 03. Here too, to enhance the contrast, it is provided that at least on a partial area or on a section of the first printed image 27 on the side of which faces away from the micro-optical structure 03 is an extensive layer 39 covering this first printed image 27, with this layer 39 preferably consisting of a lighter color than the at least one color different from white of which the first printed image 27 consists .

That now according to the 6 proposed security document 02 differs from that in the 5 shown embodiment in that a second, ie a further, printed image 41, preferably also created using an offset printing process, 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. This second printed image 41 is arranged on the part of the first printed image 27 covering layer 39 that this second printed image 41 after performing a in the 6 fold indicated by an arrow on a fold line 07 that preferably runs through the security document 02—as in FIG 4 shown by way of example - is or at least can be brought into alignment with the micro-optical structure 03 applied to the other side of the substrate 26 of this security document 02 in such a way that this second printed image 41 or at least one piece of information contained in it is in a direction from the micro-optical structure 03 Directed viewing visible and / or recognizable is or will The fold line 07, along which the substrate 26 of this security document 02 is folded, is preferably arranged outside of the layer 39 that partially covers the first printed image 27, i.e. at a distance from this layer 39. This fold line 07 is preferably in that part of the first printed image 27 arranged, which is not covered by the layer 39 arranged on the first printed image 27 .

Also in the embodiment of the invention according to 6 It can be provided that the image elements 28a to 28j of the first printed image 27 are formed in a color different from white, with the layer 39 partially covering the first printed image 27 consisting of a lighter color than the at least one color different from white which the first printed image 27 consists.

In addition, the embodiment of the invention according to the 6 in every technically meaningful combination have at least some of those features that are already associated with the 1 and 5 have been described.

Based on 7 will now be explained how a security document 02, in particular according to the 5 or 6 embodiments shown can be produced. As already mentioned, the contrast-enhancing layer 39 covering the printed image 27 in question can also be created using an offset printing process or a screen printing process, although in the preferred embodiment it is created using an inkjet printing process, whereas that on the other side opposite the micro-optical structure 03 the substrate 26 arranged relevant printed image 27 is created in an offset printing process. The printed image 27 consists of a plurality of picture elements 28a to 28j printed in at least two different printing colors, these picture elements 28a to 28j in turn forming picture elements and/or lines. A pixel size 38 or line width 38 is preferably in a range of less than 20 μm, e.g. B. in the range of about 5 microns to 10 microns. A color register of the image elements 28a to 28j printed in different printing colors, ie the accuracy of their relative arrangement to one another, is less than 20 μm, preferably less than 10 μm, and is in particular in the range of about 5 μm in the exemplary embodiments considered here.

The production of the printed image 27 with the aforementioned color register is z. B. in a trained as a rotary printing machine printing press, in particular in a printing machine used in security printing, wherein the z. B. as a substrate web or as a printed sheet formed substrate 26 via a z. B. as an impression cylinder 42 trained cylinder is performed, wherein the printing inks involved in the print image 27 in question are applied by a successive overprint on the substrate 26 or in the preferred embodiment, the printing inks involved in the print image 27 in question z. B. collected on a transfer cylinder 43 and delivered by this transfer cylinder 43 together to the substrate 26 guided by the impression cylinder 42. The substrate 26 is z. B. formed as a printing substrate in the form of a polymer film or as a printed sheet of paper.

At least two forme cylinders 44 are or at least can be set on the circumference of the transfer cylinder 43 , each of these forme cylinders 44 transferring one of the printing colors involved in the print image 27 in question to the transfer cylinder 43 . The respective direction of rotation of impression cylinder 42, transfer cylinder 43 and forme cylinder 44 is in the 7 each indicated by an arrow indicating the direction of rotation. The person skilled in the art is aware that each of the forme cylinders 44 each have one in the 7 not shown inking unit is assigned. In the preferred embodiment, the printing inks transferred from the forme cylinders 44 placed on the transfer cylinder 43 differ in their hue.

A printing device is provided on the same side of the substrate 26 as the printed image 27 created at the transfer point, downstream of the transfer point at which the transfer cylinder 43 prints the printing inks collected on it to create the print image 27 onto the substrate 26 guided by the impression cylinder 42 Printing device overprints the printed image 27 at least partially with a layer 39 of light-colored, preferably white, ink. This printing device is preferably designed as at least one inkjet print head 46 . In the preferred embodiment, the hue of the ink printed by the relevant inkjet print head 46 is lighter than the respective hue of the printing inks applied by the transfer cylinder 43 to the substrate 26 .

An embossing device 47 is preferably also provided in the printing press, with which embossing device 47 the micro-optical structure 03 consisting of microlenses 11 is formed on the substrate 26. Thus, this embossing device 47 can be arranged in the printing press upstream of the impression cylinder 42 . In a particularly advantageous embodiment, however, the impression cylinder 42 has this on its circumference Embossing device 47, the micro-optical structure 03 consisting of microlenses 11 being formed with this embossing device 47 and being arranged on the substrate 26 guided by this impression cylinder 42 during the rotation of this impression cylinder 42. the z. B. formed from a plastic or resin microlenses 11 have a lens width 18 z. B. less than 100 microns, preferably between 20 microns and 65 microns.

The result is a printing press for producing a security document 02, with an impression cylinder 42 guiding a substrate 26 of the security document 02 and a transfer cylinder 43 cooperating with the impression cylinder 42 at a transfer point and printing a printed image 27 onto the substrate 26. The substrate 26 of the security document 02 has at least one transparent window 04, with a micro-optical structure 03 consisting of microlenses 11 being provided on one side of the substrate 26 at least in the region of the relevant transparent window 04. Impression cylinder 42 and transfer cylinder 43 are arranged to work together in such a way that in a printing process, at least in the area of the relevant transparent window 04, the micro-optical structure 03 consisting of micro-lenses 11 is printed on one side of the substrate 26 and on the other side of the substrate opposite this micro-optical structure 03 26, the at least one printed image 27 can be arranged at least in the region of the transparent window 04. This arrangement of the micro-optical structure 03 consisting of microlenses 11 produced by the embossing device 47 and the at least one printed image 27 produced by the impression cylinder 42 and transfer cylinder 43 in the area of the transparent window 04 can be applied at the aforementioned transfer point at the same time or with reference to the circumference of the impression cylinder 42 different positions at different times.

A printing device is also provided in the printing press, with this printing device applying a two-dimensionally extended layer 39 that covers the printed image 27 in question to at least one section of the printed image 27 in question on its side facing away from the micro-optical structure 03. This printing device is arranged downstream of the transfer point, at which the transfer cylinder 43 prints the print image 27 onto the substrate 26 guided by the impression cylinder 42, on the same side of the substrate 26 as the print image 27 created at the transfer point, and is embodied according to the invention as at least one inkjet print head 46. In its preferred embodiment, the print image 27 in question has a plurality of image elements 28a to 28j of different colors in a dot-shaped or line-shaped grid, with these image elements 28a to 28j each being formed in a shade different from white, with the layer formed by the at least one inkjet print head 46 39 consists of a lighter hue than the hues other than white that make up the printed image 27 in question.

Advantageously, in order to maintain high register accuracy, the impression cylinder 42 has the embossing device 47 on its circumference, the embossing device 47 forming the micro-optical structure 03 consisting of micro-lenses 11 and being arranged in such a way that it presses the micro-optical structure 03 consisting of micro-lenses 11 during the rotation of this impression cylinder 42, i. H. during an ongoing printing process, on the substrate 26 guided by this impression cylinder 42 . A pixel size 38 or a line thickness 38 of the image elements 28a to 28j of the print image 27 in question is preferably each smaller than a lens width 18 of the microlenses 11 arranged in the micro-optical structure 03.

In a preferred embodiment of this printing press, at least two forme cylinders 44 are provided that are or at least can be set against the circumference of the transfer cylinder 43, each of these forme cylinders 44 transferring one of the printing colors involved in the relevant printed image 27 to the transfer cylinder 43, with the transfer cylinder 43 collecting these different-colored printing colors and wherein the inks collected on the transfer cylinder 43 are collectively transferred to the substrate 26 guided by the impression cylinder 42.

Reference List

01

security element

02

security document

03

optically imaging structure; micro-optical structure

04

Window

05

-

06

recess

07

crease line

08

-

09

-

10

-

11

microlens

12

axis of symmetry; optical axis

13

convex envelope surface

14

beam of light

15

-

16

edge point

17

edge point

18

lens width

19

main level

20

-

21

flat surface

22

focal length

23

focus

24

focal plane

25

-

26

substrate

27

print image

28

Picture element (28a to 28j)

29

material thickness; thickness

30

-

31

cutting plane

32

Cone; Winkelfeld

33

first viewing angle

34

second viewing angle

35

-

36

layer thickness

37

apex

38

pixel size; lineweight

39

layer

40

-

41

print image

42

Impression cylinder

43

transfer cylinder

44

form cylinder

45

-

46

inkjet print head

47

embossing device

Claims (9)

Method for authenticating a security document (02), the security document (02) having a transparent window (04) in its substrate (26), wherein at least in the region of the transparent window (04) on one side of the substrate (26) a microlens (11) the existing micro-optical structure (03) is arranged to partially or fully cover this window (04) and a printed image (27) is applied outside and at a distance from the area of the transparent window (04), this printed image (27) in a punctiform or linear grid consisting of image elements (28a to 28j) is applied to the substrate (26), with a pixel size (38) or a line width (38) of the image elements (28a to 28j) of the printed image (27 ) is formed smaller than a lens width (18) of the microlenses (11) arranged in the micro-optical structure (03), the substrate (26) of this security document (02) being folded at a folding line (07) and that outside and at a distance from the area of the the printed image (27) applied to the transparent window (04) is brought into congruence with the micro-optical structure (03) applied to the other side of the substrate (26) of this security document (02) in such a way that this printed image (27) or at least one contained in it Information becomes visible and/or recognizable when viewed from the direction of the micro-optical structure (03) by looking at this printed image (27), such a printing fluid being used to create the printed image (27) on the substrate (26) of the security document (02). is applied, which only becomes visible to the human eye as a result of an excitation outside of the electromagnetic spectrum visible to the human eye, characterized in that the printed image (27) applied outside and at a distance from the area of the transparent window (04) is on the micro-optical Structure (03) opposite the other side of this substrate (26) is applied, the window (04) partially or completely covered by the micro-optical structure (03) formed in the substrate (26) of the security document (02) on the micro-optical structure (03) facing away from the substrate (26) of this security document (02) has a further printed image (27), this further printed image (27) arranged in the region of the window (04) in the region covered by the micro-optical structure (03) at least has a recess (06), so that the relevant recess (06) formed in the further printed image (27) partially exposes the micro-optical structure (03) applied to the substrate (26) of this security document (02) and allows a view through the window ( 04) onto the micro-optical structure (03), the printed image (27) applied outside and at a distance from the area of the transparent window (04) being folded at least with the substrate (26) of this security document (02) at the fold line (07). one of the recesses (06) partially exposing the micro-optical structure (03) is aligned. procedure after claim 1 , characterized in that the printed image (27) with information that is immediately recognizable to humans is applied to the substrate (26) of the security document (02). procedure after claim 1 , characterized in that a solely machine-readable printed image (27) is applied to the substrate (26) of the security document (02). procedure after claim 1 or 2 or 3 , characterized in that the printed image (27) applied outside and at a distance from the area of the transparent window (04), or at least one item of information contained in it, after the substrate (26) of this security document (02) has been folded at the folding line (07) at a from the direction of the micro-optical structure (03) by this observation directed at this printed image (27) while performing a relative movement between the micro-optical structure (03) and the outside which is aligned with this micro-optical structure (03) and at a distance from the region of the transparent window ( 04) applied printed image (27) or by performing a tilting movement of the entire security document (02) folded at the fold line (07) becomes visible and/or recognizable. procedure after claim 1 or 2 or 3 or 4 , characterized in that a security document (02) designed as a bank note is used. procedure after claim 1 or 2 or 3 or 4 or 5 , characterized in that a fibrous printing material or a polymer film is used as the substrate (26). procedure after claim 1 or 2 or 3 or 4 or 5 or 6 , characterized in that a lens array or a lenticular is used as the micro-optical structure (03), the lens array or the lenticular each consisting of plano-convex microlenses (11), these microlenses (11) being rotationally symmetrical spherical or aspherical in the case of a lens array and im Case of a lenticular are axisymmetric rod-shaped. procedure after claim 1 or 2 or 3 or 4 or 5 or 6 or 7 , characterized in that the printed image (27) applied outside and at a distance from the area of the transparent window (04) and/or that on the side of the substrate (26) of the security document (02) facing away from the micro-optical structure (03) in the window ( 04) of this substrate (26) formed further print image (27) is created in an offset printing process or are each created in an offset printing process. procedure after claim 1 or 2 or 3 or 4 or 5 or 6 or 7 or 8th , characterized in that this method for self-authentication of the relevant security document (02) is used.

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