EP2040934B1 - Security element - Google Patents

Description

The invention relates to a security element for security papers, documents of value and the like and in particular relates to such a security element with a micro-optical moiré magnification arrangement. The invention further relates to a method for producing such a security element, a security paper and a data carrier with such a security element.

Data carriers, such as valuables or identity documents, but also other valuables, such as branded goods, are often provided with security elements for the purpose of security, which permit verification of the authenticity of the data carrier and at the same time serve as protection against unauthorized reproduction. The security elements can be embodied, for example, in the form of a security thread embedded in a banknote, a covering film for a banknote with a hole, an applied security strip or a self-supporting transfer element which is applied to a value document after its manufacture.

Security elements with optically variable elements, which give the viewer a different image impression under different viewing angles, play a special role, since they can not be reproduced even with high-quality color copying machines. For this purpose, the security elements can be equipped with security features in the form of diffraction-optically effective microstructures or nanostructures, such as with conventional embossed holograms or other hologram-like diffraction structures, as described, for example, in the publications EP 0 330 733 A1 or EP 0 064 067 A1 are described.

It is also known to use lens systems as security features. For example, in the document EP 0 238 043 A2 a security thread of a transparent material described on the surface of a grid of several parallel cylindrical lenses is imprinted. The thickness of the security thread is chosen so that it corresponds approximately to the focal length of the cylindrical lenses. On the opposite surface of a printed image is applied register accurate, the print image is designed taking into account the optical properties of the cylindrical lenses. Due to the focusing effect of the cylindrical lenses and the position of the printed image in the focal plane different subregions of the printed image are visible depending on the viewing angle. By appropriate design of the printed image so that information can be introduced, which are visible only at certain angles. Although a certain embodiment of the printed image also "moving" images can be generated. However, as the document rotates about an axis parallel to the cylindrical lenses, the subject moves only approximately continuously from one location on the security thread to another location.

From the publication US 5 712 731 A For example, the use of a moiré magnification arrangement is known as a security feature. The security device described therein has a regular array of substantially identical printed microimages of up to 250 μm in size and a regular two-dimensional array of substantially identical spherical microlenses. The microlens array has substantially the same pitch as the microimage array. When the micro-image array is viewed through the microlens array, one or more enlarged versions of the microimages are created to the viewer in the areas where the two arrays are substantially in register.

From the publication US 2002/0012447 A1 For example, a security element with a moiré arrangement of two grids is known which generates a moiré intensity profile in superimposition, wherein one of the grids can consist of a lens array. Furthermore, the individual motif elements can also represent different shades of gray by varying their size and shape. As a result, a grayscale image can be generated from the micromotif elements.

The principle of operation of such Moire magnification arrangements is described in the article " The moire magnifier ", MC Hutley, R. Hunt, RF Stevens and P. Savander, Pure Appl. Opt. 3 (1994), pp. 133-142 , described. In short, moiré magnification thereafter refers to a phenomenon that occurs when viewing a raster of identical image objects through a lenticular of approximately the same pitch. The resulting moiré pattern represents an enlargement and rotation of the image objects of the image grid.

The production of the Bildobjektraster takes place in the known Moiré magnification arrangements with classical printing techniques or by means of embossing techniques with various further processing steps. However, both print and suitable embossing techniques are now widely available on the market, so that such moire magnification arrangements can be relatively easily imitated by counterfeiters.

Based on this, the object of the invention is to avoid the disadvantages of the prior art and, in particular, to specify a security element with a micro-optical moiré magnification arrangement of high security against counterfeiting.

This object is achieved by the security element having the features of the main claim. A method for producing such a security element, a security paper and a data carrier with such a security element are specified in the independent claims. Further developments of the invention are the subject of the dependent claims.

• einem Motivbild, das aus einer planaren periodischen oder zumindest lokal periodischen Anordnung einer Mehrzahl von Mikromotivelementen besteht, und
• einer planaren periodischen oder zumindest lokal periodischen Anordnung einer Mehrzahl von Mikrofokussierelementen zur Moirevergrößerten Betrachtung der Mikromotivelemente des Motivbilds.

According to the invention, a generic security element includes a micro-optical moiré magnification arrangement

• a motif image consisting of a planar periodic or at least locally periodic arrangement of a plurality of micromotif elements, and
• a planar periodic or at least locally periodic arrangement of a plurality of microfocusing elements for moire magnified viewing of the micromotif elements of the motif image.

The motif image contains two or more subregions with micromotif elements differing from one another in their contrast, wherein the shape of the subregions forms macroscopic image information recognizable by the contrast differences of the micromotif elements in the form of characters, patterns or codes.

The invention is based on the idea to integrate an additional macroscopically recognizable image information and thus a higher-level security feature in the security element by a controlled individual variation of the contrast of the micromotif elements. As can be seen from the following description, this macroscopic image information can be used without additional work steps, such as demetallization Metallic coatings, and thus produce particularly economical.

In the present case, macroscopically recognizable image information is taken to mean image information that can be recognized without visual aid by the naked eye. Preferably, even the partial areas themselves each have dimensions of 0.1 mm or more.

In a first advantageous variant of the invention, the outlines of the partial regions form the macroscopic image information, while in a second likewise advantageous variant of the invention, the partial regions respectively represent regions of the same brightness level in a halftone image. In the latter case, it is not the partial areas themselves, but only the halftone image formed by them, that must be recognizable to the naked eye, in order to form macroscopic image information.

The micromotif elements of the subregions each have the same shape.

The contrast differences of the micromotif elements are produced by a variation of the stroke width and / or the stitch depth and / or the color of the micromotif elements.

The number of occurring contrast gradations of the micromotif elements is basically arbitrary. However, in many cases, the macroscopic Image information more easily recognizable with a small number of contrast gradations. The micromotif elements in the subregions are therefore preferably in two, three, four or five contrast graduations.

The contrast transitions between adjacent subareas may be discontinuous, so that the contrast changes abruptly from one subarea to the next. The contrast transitions can also be continuous, for example to produce a slowly changing contrast profile. Continuous contrast transitions include, in particular, quasi-continuous contrast transitions with small differences in contrast between adjacent subregions, which are not or hardly discernible to the naked eye.

In some designs, it is advisable to keep the contrast of the micromotif elements very low in at least one subarea. In extreme cases, the contrast of the micromotif elements may even disappear.

The lateral dimensions of the micromotif elements and the microfocusing elements are preferably below about 100 μm, preferably between about 5 μm and about 50 μm, particularly preferably between about 10 μm and about 35 μm.

In one development of the invention, the micromotif elements in the partial areas are each arranged in the form of a grid, with the grid arrangements differing in different partial areas in at least one raster parameter, in particular in the raster width, the raster orientation or the lattice symmetry of the raster.

In this case, the microfocusing element arrangement is preferably likewise subdivided into subareas in which the arrangement of the microfocusing elements is in each case matched to the raster arrangement of the associated subarea of the micromotif elements.

In a preferred embodiment of the security element according to the invention, the macroscopic image information can be seen in a transparent manner.

The arrangement of micromotif elements and the arrangement of microfocusing elements advantageously form a two-dimensional Bravais grating at least locally, the arrangement of micromotif elements and / or the arrangement of microfocusing elements forming a Bravais grating with the symmetry of a parallelogram grating.

The motif image and the arrangement of microfocusing elements are expediently arranged on opposite surfaces of an optical spacer layer. The spacer layer may comprise, for example, a plastic film and / or a lacquer layer.

The microfocusing elements of the moiré magnification arrangement can be present as transmissive, refractive or diffractive lenses or as a hybrid of these lens types. Preferably, they are formed by non-cylindrical microlenses, in particular by microlenses having a circular or polygonal limited base surface. The arrangement of microfocusing elements can moreover be provided with a protective layer whose refractive index preferably deviates by at least 0.3 from the refractive index of the microfocusing elements. In addition to protection against environmental influences, such a protective layer also prevents the microfocusing element arrangement from being easily shaped. Will the Microfocusing elements produced, for example, from paints having a refractive index of 1.2 to 1.5 are suitable as protective layers, for example, with nanoparticles of titanium oxide-filled paints, which are commercially available with refractive indices between 1.7 and 2.

The micromotif elements are preferably in the form of micro-characters or micro-patterns. In particular, the micromotif elements may be present in a printing layer. It will be understood that the micromotif elements must be substantially identical to produce the moiré magnification effect. However, a slow, in particular periodically modulated change in the appearance of the micromotif elements and thus also of the enlarged images is likewise within the scope of the invention. Also, individual or a part of the micromotif elements may be equipped with additional information that does not appear in the enlarged moiré image, but that can be used as an additional authenticity indicator.

The overall thickness of the security element is advantageously below 50 μm, which ensures that it is well suited for use in security paper, value documents or the like.

The security element itself preferably represents a security thread, a tear thread, a security tape, a security strip, a patch or a label for application to a security paper, document of value or the like. In an advantageous embodiment, the security element can span a transparent or recessed area of a data medium, for example a window area of a banknote. Different appearances can be realized on different sides of the data carrier.

The invention also includes a method for producing a security element with a micro-optical moiré magnification arrangement, in which a motif image consisting of a planar periodic or at least locally periodic arrangement of a plurality of micromotif elements, and a planar periodic or at least locally periodic arrangement of a plurality of Microfocusing be arranged so that the micromotif elements are magnified when viewed through the Mikrofokussierelemente recognizable, wherein the motif image is formed with two or more sub-areas with mutually differing in their contrast micromotifs such that the shape of the sub-areas recognizable by the contrast differences of the micromotifs macroscopic Image information in the form of characters, patterns or encodings forms.

A security paper according to the invention for the production of security or value documents, such as banknotes, checks, identity cards, certificates or the like, is provided with a security element of the type described above. The security paper may in particular comprise a carrier substrate made of paper or plastic.

The invention also includes a data carrier, in particular a brand article, a value document or the like, with a security element of the type described above. The security element can be arranged in particular in a window area, ie a transparent or recessed area of the data carrier.

Further embodiments and advantages of the invention are explained below with reference to the figures. For better clarity, in The figures waived a true to scale and proportions representation.

Fig. 1

eine schematische Darstellung einer Banknote mit einem eingebetteten Sicherheitsfaden und einem über einem Durchsichtsbereich angeordneten Durchsichtssicherheitselement,

Fig. 2

schematisch den Schichtaufbau eines erfindungsgemäßen Sicherheitselements im Querschnitt,

Fig. 3

in (a) das Motivbild eines erfindungsgemäßen Sicherheitselements in Aufsicht, in (b) das Erscheinungsbild des Sicherheitselements bei Betrachtung in Aufsicht und in (c) das Erscheinungsbild des Sicherheitselements bei Betrachtung in Durchsicht,

Fig. 4

Mikromotivelemente in Ausschnitten aus Teilbereichen von Motivbildern, wobei (a) und (b) den in Fig. 3(a) gezeigten Ausschnitten entsprechen, und (c) bis (e) Abwandlungen des in (b) dargestellten Rasters zeigen,

Fig. 5

ein erfindungsgemäßes Durchsichtssicherheitselement nach einem weiteren Ausführungsbeispiel der Erfindung, wobei (a) eine schematische Aufsicht auf das Motivbild des Durchsichtssicherheitselements, (b) den visuellen Eindruck bei Betrachtung des Motivbilds in Aufsicht und (c) den visuellen Eindruck bei Betrachtung in Durchsicht zeigt, und

Fig. 6

den visuellen Eindruck bei Betrachtung eines Sicherheitselements nach einem weiteren Ausführungsbeispiel der Erfindung in Aufsicht.

Show it:

Fig. 1

a schematic representation of a banknote with an embedded security thread and arranged over a see-through range see-through security element,

Fig. 2

schematically the layer structure of a security element according to the invention in cross-section,

Fig. 3

in (a) the motif image of a security element according to the invention in a plan view, in (b) the appearance of the security element when viewed in a plan view and in (c) the appearance of the security element when viewed in phantom,

Fig. 4

Micromotifs in excerpts of subregions of motif images, where (a) and (b) represent the in Fig. 3 (a) and (c) to (e) show modifications of the grid shown in (b),

Fig. 5

an inventive see-through safety element according to a further embodiment of the invention, wherein (a) shows a schematic plan view of the motif image of the see-through security element, (b) the visual impression when viewing the motif image in supervision and (c) the visual impression when viewed in phantom, and

Fig. 6

the visual impression when viewing a security element according to another embodiment of the invention in supervision.

The invention will now be explained using the example of a security element for a banknote. Fig. 1 shows a schematic representation of a banknote 10, which is provided with two security elements 12 and 16 according to embodiments of the invention. In this case, the first security element represents a security thread 12 which protrudes at certain window areas 14 on the surface of the banknote 10, while it is embedded in the intervening areas in the interior of the banknote 10. The second security element is designed in the form of a see-through security element 16 which is arranged above a see-through region 18, for example a window region or a through-opening of the banknote 10.

Both the security thread 12 and the see-through security element 16 may include a moire magnification arrangement with additional macroscopic image information according to an embodiment of the invention. First, the principle of operation of inventive micro-optical moiré magnification arrangements with reference to the Fig. 2 briefly explained.

Fig. 2 schematically shows the layer structure of a security element according to the invention 20 in cross section, wherein only the parts of the layer structure required for the explanation of the principle of operation are shown. The security element 20 includes an optical spacer layer 22, the upper side of which is provided with a regular array of microlenses 24. The arrangement of the microlenses 24 forms a region in each case one Grid with preselected grid parameters, such as grid width, grid orientation and grid symmetry. The lattice symmetry can be described by a two-dimensional Bravais lattice, for the sake of simplicity of which hexagonal symmetry is assumed for the following explanation, although the Bravais lattice according to the invention may have a lower symmetry and thus a more general shape.

On the underside of the spacer layer 22, a motif layer 26 is arranged, which contains a likewise grid-shaped arrangement of similar micromotif elements 28. The arrangement of the micromotif elements 28 can also be described by a two-dimensional Bravais lattice with a preselected symmetry, again assuming a hexagonal lattice symmetry for illustration. As in Fig. 2 indicated by the offset of the micromotif elements 28 relative to the microlenses 24, the Bravais lattice of the micromotif elements 28 differs slightly in its symmetry and / or in the size of the lattice parameters from the Bravais lattice of the microlenses 24 to produce the desired moire magnification effect ,

The distance of adjacent microlenses 24 is preferably chosen as small as possible in order to ensure the highest possible area coverage and thus a high-contrast representation. The spherically or aspherically configured microlenses 24 have a diameter of between 5 μm and 50 μm, preferably only between 10 μm and 35 μm, and are therefore invisible to the naked eye. The grating period and the diameter of the micromotif elements 28 are of the same order of magnitude as those of the microlenses 24, that is to say in the range from 5 μm to 50 μm, preferably from 10 μm to 35 μm, so that the micromotif elements 28 themselves can not be recognized by the naked eye are.

The optical thickness of the spacer layer 22 and the focal length of the microlenses 24 are matched to one another such that the micromotif elements 28 are approximately at a distance of the lens focal length. Due to the slightly differing lattice parameters, when the security element 20 is viewed from above through the microlenses 24, the viewer sees a slightly different subarea of the micromotif elements 28, so that the large number of microlenses overall produces an enlarged image of the micromotif elements 28.

The resulting moiré magnification depends on the relative difference of the lattice parameters of the Bravais lattice used. If, for example, the grating periods of two hexagonal gratings differ by 1%, the result is a 100-fold moire magnification. For a more detailed illustration of the mode of operation and advantageous arrangements of the micromotif elements and the microlenses, reference is made to the co-pending German patent application 10 2005 062 132.5 referenced, the disclosure of which is included in the present application in this respect.

In such Moiré magnification arrangements, the motif image is now formed according to the invention with two or more sub-areas, each containing in their contrast mutually differing micromotif elements and forms a form recognizable by the contrast differences of the micromotif elements macroscopic image information in the form of characters, patterns or codes ,

Fig. 3 (a) shows a schematic plan view of the motif image 30 of a see-through security element according to an embodiment of the invention, in the manner explained above via an optical spacer layer 22 is connected to a microlens array 24. The motif image 30 contains a plurality of micromotif elements 36, 38 of identical shape but locally different in contrast. The different contrast arises in the exemplary embodiment in that the micromotif elements 36 are formed in a first subregion 32 of the motif image 30 with a low line width, while the micromotif elements 38 of a second subregion 34 are formed with a large line thickness.
The outline of the subregions 32, 34 forms a macroscopic image information, in the exemplary embodiment the letter "A". The dimensions of the macroscopic image information "A" are typically in the range of a few millimeters or centimeters and are therefore significantly larger than the micromotif elements 36, 38 whose dimensions are only in the range of a few tens of micrometers. Accordingly, the micromotif elements 36, 38 in the Fig. 3 (a) only shown in enlarged detail cutouts 42, 44 of the sections 32, 34 individually.

The micromotif elements 36, 38 of the two subareas are formed with identical shape, in the embodiment in the form of a 5-pointed star, but different line thickness. Accordingly, when viewing the motif image 30 through the microlens array 24, as in the Auflichtsituation the Fig. 3 (b) With an assumed 100-fold moiré magnification of the see-through security element, the dimensions of the images 46, 48 are then 100 times greater than the dimensions of the micromotif elements 36, 38.

• Zum einen nimmt der Betrachter den Moiré-Vergrößerungseffekt mit vergrößerten Bildern 46, 48 der Mikromotivelemente 36, 38 wahr, der mit den von Moiré-Vergrößerungsanordnungen bekannten Bewegungseffekten beim Verkippen des Sicherheitselements verbunden ist. Beispielsweise können das Motivbild 30 und das Mikrolinsenarray 24 auf das Auftreten eines orthoparallaktischen Bewegungseffekts ausgelegt sein, bei dem sich die vergrößerten Bilder 46, 48 senkrecht zur Kipprichtung bewegen und nicht parallel zur Kipprichtung, wie man intuitiv erwarten würde. Je nach Wahl der Brennweiten der Mikrolinsen 24 sowie der Differenz der Gitterparameter können die Bilder 46, 48 auch vor oder hinter der Bildebene des Sicherheitselements zu schweben scheinen.

For the viewer are in the reflected light viewing situation of the Fig. 3 (b) two overlapping optical effects visible:

• On the one hand, the viewer perceives the moiré magnification effect with enlarged images 46, 48 of the micromotif elements 36, 38, which is associated with the motion effects known from moiré magnification arrangements when tilting the security element. For example, the motif image 30 and the microlens array 24 may be configured for the appearance of an ortho-parallactic motion effect in which the magnified images 46, 48 are perpendicular to the tilt direction and not parallel to the tilt direction, as one would intuitively expect. Depending on the choice of the focal lengths of the microlenses 24 and the difference of the grating parameters, the images 46, 48 may seem to float in front of or behind the image plane of the security element.

The second optical effect is formed by the macroscopic variation of the contrast of the moire magnified images 46, 48 in the subregions 32 and 34, respectively. This optical effect leads to the representation of a macroscopic image information which is stationary relative to the plane of the security element and which in the exemplary embodiment is represented by the in Fig. 3 (b) clearly recognizable outline of the letter "A" is formed.

On the other hand, when the subject image 30 of the see-through security element is viewed by the micromotif element array as in FIG Fig. 3 (c) shown as a transmitted light situation, then only the fixed contrast difference of the partial areas 32 and 34 can be seen. A moiré magnification effect does not occur in this viewing situation, thus giving the viewer the image impression of a dark letter "A" against a light background, as in FIG Fig. 3 (c) shown.

Instead of or in addition to the line width, the stitch depth and / or the color of the micromotif elements in the subregions can also be varied in order to: to obtain a different contrast effect. In addition to discontinuous contrast transitions with a sudden change in the contrast, continuous contrast transitions can also be realized, for example by a continuous increase or decrease in the line width of the micromotif elements.

The number of different contrast gradations in a motif image is basically arbitrary. A limited number of contrast gradations, however, in many applications leads to an easier recognizability of the macroscopic information, so that currently designs with two to five contrast graduations are preferred.

In the subregions 32, 34, in which the micromotif elements differ from one another in terms of contrast, the rasters in which the respective micromotif elements are arranged can additionally be designed differently, as can be seen from FIGS Fig. 4 illustrated.

The FIGS. 4 (a) and 4 (b) show again first the micromotif elements 36 and 38 in the cutouts 42 and 44 of the Fig. 3 (a) both arranged in a grid with hexagonal lattice symmetry. With a constant design of the grid arrangement in the partial area 32 (FIG. Fig. 4 (a) ), the micromotif elements 38 of the portion 34 can then be arranged, for example, in a hexagonal grid of greater screen width, as in Fig. 4 (c) represented in a hexagonal grid of the same screen width, but different orientation, as in Fig. 4 (d) shown, or in a grid with other, for example, square lattice symmetry, as in Fig. 4 (e) shown. Of course, more than one screen parameter can be varied at the same time.

The grid arrangement of the associated microlenses 24 is suitably matched to the grid arrangement of the micromotif elements 36, 38 in the respective subareas. As a result of the variation of the raster parameters, the stationary contrast variation described above can be extended by a further optical effect, namely by a variation of the primary moiré magnification effect in the different subregions 32, 34. For example, the in Fig. 3 the interior of the letter "A" performing partial area 34 have a different moire magnification than the partial area 32, so that the motif elements appear there not only with different contrast, but also at a different magnification. In another variant, the motion effects in the subregions 32, 34 can differ from one another, such that the magnified images 46, 48 move in different directions when the security element is tilted in the subregions 32, 34.

A further embodiment of a see-through security element according to the invention is shown in FIG Fig. 5 shown, where Fig. 5 (a) shows a schematic plan view of the motif image 50 of the see-through security element, Fig. 5 (b) the visual impression when viewing the motif image 50 in supervision and Fig. 5 (c) represents the visual impression when viewed in review.

The motif image 50 contains a plurality of micromotif elements 62, 64, 66 with identical shape, in the exemplary embodiment in the form of a 5-pointed star, but locally different line thickness and thus locally different contrast. In a first subregion 52, the micromotif elements 62 are designed with a very low line width, while the micromotif elements 64 and 66 are formed in the subregion 54 or 56 with medium or large line thickness. The respective micromotiv elements of the same line thickness containing portions are in the embodiment of Fig. 5 not connected and are therefore for illustrative purposes filled with a narrow hatching (portion 56), a wide hatching filled (portion 54) or not hatched (portion 52).

The subregions 52, 54, 56 each represent regions of the same brightness level in a halftone image, such as a portrait. Often, three brightness levels, corresponding to the white, gray and black tonal values, are sufficient to produce a halftone image that is easily recognizable to the human eye , The dimensions of the halftone image are in the macroscopic range, the motif image 50 thus represents an image information recognizable with the naked eye. Accordingly, the micromotif elements 62, 64, 66, which are substantially smaller with, for example, about 30 μm, are as in the case of FIG Fig. 3 (a) , shown only in enlarged sections of the sections 52, 54, 56.

When viewing the security element in supervision, two optical effects occur at the same time, as in Fig. 5 (b) illustrated. On the one hand, a moiré magnification effect with enlarged images 72, 74, 76 of the micromotif elements and the motion effects already mentioned can be recognized by the observer. In addition, the macroscopic variation of the contrast of the moire magnified images 72, 74, 76 in the subregions 52, 54, 56 also reveals a halftone image. This forms stationary macroscopic image information, which performs no relative movement with tilting of the security element, unlike the individual enlarged images 72, 74, 76.

When viewing the security element in review, no moiré magnification effect occurs, but rather only the fixed contrast difference of the subregions 52, 54, 56 and thus the halftone image W recognizable. For the viewer, there is a picture impression, as in Fig. 5 (c) shown.

In the further embodiment of the Fig. 6 For example, a security element 80 includes a motif image with micromotif elements that, in addition to different contrasts, also have different shapes. With reference to the in Fig. 6 When the security element is viewed in plan view, a first subarea 82 contains micromotif elements of a first shape (star) and with a low line width. A second portion 84 contains micromotif elements of the same shape (star) with a large line width. A third subregion 86 contains micromotif elements of a second shape (symbol) with a low line width, while a fourth subregion 88 contains micromotif elements of the second shape (symbol) with a large line width.

The first and second partial regions 82, 84 and the third and fourth partial regions 86, 88 form macroscopic image information with their outlines, in the exemplary embodiment the letter sequence "PL".

In the supervision of the security element 80, the two already arise in connection with the Fig. 3 described effects, which additionally differ the enlarged images of the micromotif elements in the subregions of the letters "P" (sub-areas 82, 84) and "L" (sub-areas 86, 88). In transmitted light, in contrast, none of the micromotif elements can be recognized because of the lack of the moiré magnification effect; the letter sequence "PL" appears uniformly dark against a light background with the same contrast difference between the micromotiv elements involved.

Claims (17)

1. A security element for security papers, value documents and the like, having a micro-optical moiré magnification arrangement having

   - a motif image that consists of a planar periodic or at least locally periodic arrangement of a plurality of micromotif elements, and

   - a planar periodic or at least locally periodic arrangement of a plurality of microfocusing elements for the moiré-magnified viewing of the micromotif elements of the motif image,

   the motif image including two or more sub-regions having micromotif elements that differ from each other in their contrast, and the shape of the sub-regions forming a macroscopic piece of image information, in the form of characters, patterns or codes, that is perceptible due to the contrast differences in the micromotif elements, and wherein the contrast differences in the micromotif elements are produced by a variation in the line width and/or the line depth and/or the color of the micromotif elements, wherein the micromotif elements of the sub-regions each exhibit the same shape.
2. The security element according to claim 1, characterized in that the sub-regions each have dimensions of 0.1 mm or more.
3. The security element according to claim 1 or 2, characterized in that the contours of the sub-regions form the macroscopic piece of image information.
4. The security element according to claim 1 or 2, characterized in that the sub-regions each depict regions of identical brightness level in a halftone image.
5. The security element according to at least one of claims 1 to 4, characterized in that the micromotif elements are present in the sub-regions in two, three, four or five contrast gradations.
6. The security element according to at least one of claims 1 to 5, characterized in that the contrast transitions between adjacent sub-regions are continuous or discontinuous.
7. The security element according to at least one of claims 1 to 6, characterized in that the contrast of the micromotif elements is very low in at least one sub-region.
8. The security element according to at least one of claims 1 to 7, characterized in that the lateral dimensions of the micromotif elements and the microfocusing elements are below about 100 µm, preferably between about 5 µm and about 50 µm, particularly preferably between about 10 µm and about 35 µm.
9. The security element according to at least one of claims 1 to 8, characterized in that the micromotif elements in the sub-regions are each arranged in the form of a grid and the grid arrangements in different sub-regions differ in at least one grid parameter, especially in the line screen, the grid orientation or the lattice symmetry of the grid, and preferably that the microfocusing element arrangement is subdivided into sub-regions in which the arrangement of the microfocusing elements is coordinated in each case with the grid arrangement of the associated sub-region of the micromotif elements.
10. The security element according to at least one of claims 1 to 9, characterized in that the macroscopic piece of image information is perceptible in transmission.
11. The security element according to at least one of claims 1 to 10, characterized in that the arrangement of micromotif elements and the arrangement of microfocusing elements each forms, at least locally, a two-dimensional Bravais lattice, the arrangement of micromotif elements and/or the arrangement of microfocusing elements forming a Bravais lattice having the symmetry of a parallelogram lattice.
12. The security element according to at least one of claims 1 to 11, characterized in that the motif image and the arrangement of microfocusing elements are arranged at opposing surfaces of an optical spacing layer.
13. The security element according to at least one of claims 1 to 12, characterized in that the microfocusing elements are formed by non-cylindrical microlenses, especially by microlenses having a circular or polygonally delimited base area.
14. The security element according to at least one of claims 1 to 13, characterized in that the micromotif elements are present in the form of microcharacters or micropatterns.
15. The security element according to at least one of claims 1 to 14, characterized in that the security element is a security thread, a tear strip, a security band, a security strip, a patch or a label for application to a security paper, value document, branded article or the like, and is preferably arranged in a window region of the security paper, value document, branded article, or the like.
16. A method for manufacturing a security element having a micro-optical moiré magnification arrangement, in which a motif image that consists of a planar periodic or at least locally periodic arrangement of a plurality of micromotif elements, and a planar periodic or at least locally periodic arrangement of a plurality of microfocusing elements are arranged such that the micromotif elements are perceptible in magnification when viewed through the microfocusing elements, wherein the motif image having two or more sub-regions having micromotif elements that differ from each other in their contrast are developed in such a way that, due to the contrast differences in the micromotif elements, the shape of the sub-regions forms a perceptible macroscopic piece of image information in the form of characters, patterns or codes, and wherein the contrast differences in the micromotif elements are produced by a variation in the line width and/or the line depth and/or the color of the micromotif elements, wherein the micromotif elements of the sub-regions each exhibit the same shape.
17. A security paper for manufacturing security or value documents, such as banknotes, checks, identification cards, certificates or the like, that is furnished with a security element according to at least one of claims 1 to 15, and preferably comprises a carrier substrate composed of paper or plastic.

Images