EP2040934B2 - 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 documents of value or identity documents, but also other valuable objects, such as branded articles, are often provided with security elements for security purposes, which allow the authenticity of the data carrier to be checked and which at the same time serve as protection against unauthorized reproduction. The security elements can be designed, for example, in the form of a security thread embedded in a banknote, a cover 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 production.

Security elements with optically variable elements play a special role here, giving the viewer a different image impression from different viewing angles, since these cannot 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 optically diffractive micro- or nanostructures, such as with conventional embossed holograms or other hologram-like diffraction structures, as described, for example, in the documents 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 publication EP 0 238 043 A2 describes a security thread made of a transparent material, on the surface of which a pattern of several parallel cylindrical lenses is embossed. 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, a printed image is applied in register, the printed image being 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 sub-areas of the printed image are visible depending on the viewing angle. By designing the print image accordingly, information can be introduced that is only visible from certain viewing angles. "Moving" images can also be generated by a specific configuration of the printed image. When the document is rotated around an axis running parallel to the cylindrical lenses, the motif only moves approximately continuously from one place on the security thread to another place.

From the publication US 5 712 731 A the use of a moiré magnification arrangement is known as a security feature. The security device described there has a regular arrangement of essentially identical printed microimages with a size of up to 250 μm and a regular two-dimensional arrangement of essentially identical spherical microlenses. The microlens arrangement has essentially the same division as the microimage arrangement. If the micro-image arrangement is viewed through the microlens arrangement, one or more enlarged versions of the micro-images are generated for the viewer in the areas in which the two arrangements are essentially in register.

From the publication US 2002/0012447 A1 a security element with a moiré arrangement consisting of two grids is known which generates a moiré intensity profile in superimposition, it being possible for one of the grids to 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 moiré 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 enlargement then refers to a phenomenon that occurs when viewing a grid of identical image objects through a lenticular grid with approximately the same grid size. The resulting moiré pattern represents an enlargement and rotation of the picture objects of the picture grid.

In the known moiré enlargement arrangements, the image object grids are produced using classic printing techniques or else using embossing techniques with various further processing steps. However, both printing and suitable embossing techniques are now generally available on the market, so that such moiré enlargement arrangements can be copied relatively easily by counterfeiters.

Proceeding from this, the object of the invention is to avoid the disadvantages of the prior art and, in particular, to provide a security element with a micro-optical moiré magnification arrangement with a high level of security against forgery.

This object is achieved by the security element with 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. 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 moiré-enlarged viewing of the micromotif elements of the motif image.

The motif image contains two or more subareas with their contrasting micromotif elements, the shape of the subareas forming 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 of integrating additional macroscopically recognizable image information and thus a security feature of a higher level into the security element through a controlled individual variation of the contrast of the micromotif elements. As is clear from the following illustration, this macroscopic image information can be generated without additional work steps, such as the demetallization of metallic cover layers, and is therefore particularly economical.

In the present case, macroscopically recognizable image information is understood to mean image information recognizable with the naked eye without optical aids. 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 areas form the macroscopic image information, while in a second likewise advantageous variant of the invention the partial areas each represent areas 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 can be seen with the naked eye in order to form macroscopic image information.

The micromotif elements of the partial areas each have the same shape.

The contrast differences of the micromotif elements are generated by varying the line width and / or the line depth and / or the color of the micromotif elements.

The number of contrast gradations of the micromotif elements that occur is basically arbitrary. In many cases, however, the macroscopic image information can be recognized more easily with a small number of contrast gradations. The micromotif elements in the partial areas are therefore preferably in two, three, four or five contrast gradations.

The contrast transitions between adjacent partial areas can be discontinuous, so that the contrast changes abruptly from one partial area to the next. The contrast transitions can, however, also be continuous, for example in order to produce a slowly changing contrast curve. Continuous contrast transitions include, in particular, quasi-continuous contrast transitions with small contrast differences between adjacent subregions that are invisible or hardly noticeable to the eye.

In some designs, it makes sense to keep the contrast of the micromotif elements very low in at least one partial area. In extreme cases, the contrast of the micromotif elements can even disappear.

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

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

In this case, the microfocusing element arrangement is preferably also subdivided into subregions in which the arrangement of the microfocusing elements is matched to the grid arrangement of the associated subregion of the micromotif elements.

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

The arrangement of micromotif elements and the arrangement of microfocusing elements each 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 can 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 mixed form of these lens types. They are preferably formed by non-cylindrical microlenses, in particular by microlenses with a circular or polygonally limited base area. The arrangement of microfocusing elements can also be provided with a protective layer, the refractive index of which 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 molded. If the microfocusing elements are made of lacquer with a refractive index manufactured from 1.2 to 1.5 are suitable as protective layers, for example lacquers filled with nanoparticles of titanium oxide, which are commercially available with refractive indices between 1.7 and 2.

The micro motif elements are preferably in the form of micro characters or micro patterns. In particular, the micromotif elements can be present in a print layer. It goes without saying that the micromotif elements for generating the moiré magnification effect have to be largely identical. However, a slow, in particular periodically modulated change in the appearance of the micromotif elements and thus also in the enlarged images is also within the scope of the invention. Individual or a part of the micromotif elements can also be provided with additional information which does not appear in the enlarged moiré image, but which can be used as an additional authenticity indicator.

The total 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, security document or the like. In an advantageous embodiment, the security element can span, for example, a transparent or recessed area of a data carrier 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 of the type described above with a micro-optical moiré magnification arrangement, in which a motif image, which 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 An arrangement of a plurality of microfocusing elements can be arranged such that the micromotif elements can be seen enlarged when viewed through the microfocusing elements, the motif image being formed with two or more sub-areas with micromotif elements differing in their contrast, such that the shape of the sub-areas is one due to the contrast differences of the micromotif elements forms recognizable macroscopic image information in the form of characters, patterns or codes.

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 equipped with a security element of the type described above. The security paper can in particular comprise a carrier substrate made of paper or plastic.

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

Further exemplary embodiments and advantages of the invention are explained below with reference to the figures. For the sake of clarity, the figures are not drawn to scale and proportion.

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 nicht 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 nicht erfindungsgemäßes Durchsichtssicherheitselement nach einem weiteren illustrierenden Beispiel, 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 nicht erfindungsgemäßen Sicherheitselements nach einem weiteren illustrierenden Beispiel in Aufsicht.

Show it:

Fig. 1

1 shows a schematic illustration of a banknote with an embedded security thread and a see-through security element arranged above a see-through area,

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 not according to the invention in supervision, in (b) the appearance of the security element when viewed in supervision and in (c) the appearance of the security element when viewed in transparency,

Fig. 4

Micromotif elements in sections from partial areas of motif images, whereby (a) and (b) the in Fig. 3 (a) correspond to the sections shown, and (c) to (e) show modifications of the grid shown in (b),

Fig. 5

a see-through security element not according to the invention according to a further illustrative example, wherein (a) shows a schematic view of the motif image of the see-through security element, (b) shows the visual impression when the motif image is viewed in supervision and (c) shows the visual impression when viewed in review, and

Fig. 6

the visual impression when viewing a security element according to another illustrative example 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 bank note 10 which is provided with two security elements 12 and 16 according to embodiments of the invention. The first security element represents a security thread 12 which emerges from certain window areas 14 on the surface of the bank note 10, while it is embedded in the areas in between inside the bank note 10. The second security element is in the form of a see-through security element 16, which is arranged above a see-through area 18, for example a window area or a continuous opening of the banknote 10.

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

Fig. 2 schematically shows the layer structure of a security element 20 according to the invention in cross section, only the parts of the layer structure required for the explanation of the functional principle being shown. The security element 20 contains an optical spacer layer 22, the upper side of which is provided with a regular arrangement of microlenses 24. The arrangement of the microlenses 24 forms a grid with preselected grid parameters, such as grid width, grid orientation and grid symmetry. The lattice symmetry is described by a two-dimensional Bravais lattice, with a hexagonal symmetry being assumed for the sake of simplicity, even if the Bravais lattice according to the invention has a lower symmetry and thus a more general shape.

A motif layer 26 is arranged on the underside of the spacer layer 22 and also contains a grid-like arrangement of similar micromotif elements 28. The arrangement of the micromotif elements 28 is also described by a two-dimensional Bravais grating with a preselected symmetry, with a hexagonal grating symmetry again being assumed 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 in order to produce the desired moiré magnification effect ,

The distance between adjacent microlenses 24 is preferably chosen to be as small as possible in order to ensure the greatest possible area coverage and thus a high-contrast display. The spherical or aspherical microlenses 24 have a diameter between 5 microns and 50 microns, preferably only between 10 microns and 35 microns and are therefore not visible to the naked eye. The grating period and the diameter of the micromotif elements 28 are of the same order of magnitude as that 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 cannot be seen even with the naked eye are.

The optical thickness of the spacer layer 22 and the focal length of the microlenses 24 are coordinated with one another in such a way that the micromotif elements 28 are approximately at the distance from the lens focal length. Due to the slightly different grating parameters, the viewer sees a somewhat different sub-area of the micromotif elements 28 when the security element 20 is viewed from above through the microlenses 24, so that the multitude of microlenses as a whole produces an enlarged image of the micromotif elements 28.

The resulting moiré magnification depends on the relative difference in the lattice parameters of the Bravais grids used. If, for example, the lattice periods of two hexagonal lattices differ by 1%, the result is a 100-fold moiré magnification. For a more detailed description of the functioning and arrangements of the micromotif elements and the microlenses, reference is also made to the pending German patent application 10 2005 062 132.5 referenced, the disclosure content of which is included in the present application.

In such moiré magnification arrangements, the motif image is now designed according to the invention with two or more partial areas, each of which contains micromotif elements that differ from one another in contrast and whose shape forms macroscopic image information in the form of characters, patterns or codes that can be recognized by the contrast differences of the micromotif elements ,

Fig. 3 (a) shows a schematic top view of the motif image 30 of a see-through security element according to an illustrative example, which is connected in the manner explained above via an optical spacer layer 22 to a microlens array 24. The motif image 30 contains a plurality of micromotif elements 36, 38 with an identical shape but a different local contrast. The different contrast in the exemplary embodiment arises from the fact that the micromotif elements 36 are formed in a first partial area 32 of the motif image 30 with a small stroke width, while the micromotif elements 38 of a second partial area 34 are formed with a large stroke width.

The micromotif elements 36, 38 of the two subregions are of identical shape, in the example in the form of a 5-pointed star, but of different line thickness. Correspondingly, when the motif image 30 is viewed through the microlens array 24, as is the case in the incident light situation Fig. 3 (b) is shown, locally differently contrasting enlarged images 46 and 48. Assuming 100 times moiré magnification of the see-through security element, the dimensions of the images 46, 48 are then 100 times larger 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, in the incident light viewing situation, the Fig. 3 (b) two overlapping optical effects can be seen:

• On the one hand, the viewer perceives the moiré enlargement effect with enlarged images 46, 48 of the micromotif elements 36, 38, which is associated with the movement effects known from moiré enlargement arrangements when the security element is tilted. For example, the motif image 30 and the microlens array 24 can be designed for the occurrence of an orthoparallactic movement effect in which the enlarged images 46, 48 move 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 in the grating parameters, the images 46, 48 can also appear 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 moiré-enlarged images 46, 48 in the partial areas 32 and 34, respectively. This optical effect leads to the representation of macroscopic image information which is stationary with respect to the level of the security element and which in the example is represented by the in Fig. 3 (b) clearly recognizable outline of the letter "A" is formed.

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

Instead of or in addition to the line width, the line depth and / or the color of the micromotif elements in the partial areas can also be varied in order 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 achieved, for example by continuously increasing or decreasing the line width of the micromotif elements.

In principle, the number of different contrast gradations in a subject image is arbitrary. However, a limited number of contrast gradations leads to easier recognition of the macroscopic information in many applications, so that designs with two to five contrast gradations are currently preferred.

In the subregions 32, 34, in which the micromotif elements differ from one another in contrast, the rasters in which the respective micromotif elements are arranged can also be designed differently, as shown in FIG Fig. 4 illustrated.

The Figures 4 (a) and 4 (b) initially show the micromotif elements 36 and 38 in the cutouts 42 and 44 of FIG Fig. 3 (a) , both of which are arranged for the sake of simplicity in a grid with hexagonal lattice symmetry not according to the invention. If the grid arrangement in sub-area 32 remains the same ( Fig. 4 (a) ), the micromotif elements 38 of the partial area 34 can then be arranged, for example, in a hexagonal grid with a larger grid width, as in FIG Fig. 4 (c) shown in a hexagonal grid of the same grid size but different orientation, as in Fig. 4 (d) shown, or in a grid with a different, for example not square inventive grid symmetry, as in Fig. 4 (e) shown. Of course, more than one raster parameter can also be varied at the same time.

The grid arrangement of the associated microlenses 24 is expediently matched to the grid arrangement of the micromotif elements 36, 38 in the respective partial areas. By varying the raster parameters, the stationary contrast variation described above can be expanded by a further optical effect, namely by a variation of the primary moiré magnification effect in the different partial areas 32, 34. For example, the in Fig. 3 the partial area 34 representing the inside of the letter "A" has a different moiré magnification than the partial area 32, so that the motif elements appear there not only with a different contrast, but also in a different magnification. In another variant, the movement effects in the partial areas 32, 34 can differ from one another, so that the enlarged images 46, 48 move in different directions when the security element is tilted in the partial areas 32, 34.

Another example of a see-through security element is in Fig. 5 shown, where Fig. 5 (a) 2 shows a schematic top view of the motif image 50 of the see-through security element, Fig. 5 (b) the visual impression when viewing the motif image 50 under supervision and Fig. 5 (c) represents the visual impression when viewed in transparency.

The motif image 50 contains a plurality of micromotif elements 62, 64, 66 with an 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 partial area 52, the micromotif elements 62 are very small Line width is formed, while the micromotif elements 64 and 66 are formed in the subarea 54 and 56 with medium or large line widths. The partial areas each containing micromotif elements of the same line thickness are in the exemplary embodiment of FIG Fig. 5 are not contiguous and are therefore filled with a narrow hatching (partial area 56), a wide hatching (partial area 54) or not hatched (partial area 52) for illustration.

The partial areas 52, 54, 56 each represent areas of the same brightness level in a halftone image, such as a portrait. Three brightness levels, corresponding to the tonal values white, gray and black, are often sufficient to produce a halftone image that is easily recognizable for the human eye , The dimensions of the halftone image lie in the macroscopic range, the motif image 50 thus represents image information that can be seen with the naked eye Fig. 3 (a) , only shown in enlarged sections of the partial areas 52, 54, 56.

When looking at the security element from above, two optical effects occur simultaneously, as in Fig. 5 (b) illustrated. On the one hand, the viewer can see a moiré magnification effect with enlarged images 72, 74, 76 of the micromotif elements and the movement effects already mentioned. In addition, the macroscopic variation in the contrast of the moiré-enlarged images 72, 74, 76 in the partial regions 52, 54, 56 also shows a halftone image. This forms a fixed macroscopic image information which, unlike the individual enlarged images 72, 74, 76, does not perform any relative movement when the security element is tilted.

When the security element is viewed in a transparent manner, there is no moiré magnification effect; rather, only the fixed contrast difference of the partial areas 52, 54, 56 and thus the halftone image W can be seen. For the viewer there is an image impression, as in Fig. 5 (c) shown.

In the further example of the Fig. 6 A security element 80 contains a motif image with micromotif elements which, in addition to different contrasts, also have different shapes. With respect to the in Fig. 6 The image impression shown when the security element is viewed from above contains a first partial area 82 micromotif elements of a first shape (star) and with a small line width. A second partial area 84 contains micromotif elements of the same shape (star) with a large line width. A third section 86 contains micromotif elements of a second shape (symbol) with a small stroke width, while a fourth section 88 contains micromotif elements of the second form (symbol) with a large stroke width.

The outlines of the first and second partial areas 82, 84 and the third and fourth partial areas 86, 88 form macroscopic image information, in the exemplary embodiment the letter sequence “PL”.

When the security element 80 is viewed from above, the two already arise in connection with the Fig. 3 effects described, the enlarged images of the micromotif elements additionally differing in the partial areas of the letters "P" (partial areas 82, 84) and "L" (partial areas 86, 88). In contrast, due to the lack of the moiré magnification effect, none of the micromotif elements can be seen in transmitted light, the letter sequence "PL" appears uniformly dark against a light background with the same difference in contrast between the micromotif elements involved.

Claims (16)

1. A security element for security papers, value documents and the like, having a micro-optical moire 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 moire-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, the arrangement of micromotif elements and the arrangement of microfocusing elements each forming, at least locally, a two-dimensional Bravais lattice, characterized in that the arrangement of micromotif elements and/or the arrangement of microfocusing elements form a Bravais lattice having the symmetry of a parallelogram lattice.
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 motif image and the arrangement of microfocusing elements are arranged at opposing surfaces of an optical spacing layer.
12. The security element according to at least one of claims 1 to 11, characterized in that the microfocusing elements are formed by non-cylindrical microlenses, especially by microlenses having a circular or polygonally delimited base area.
13. The security element according to at least one of claims 1 to 12, characterized in that the micromotif elements are present in the form of microcharacters or micropatterns.
14. The security element according to at least one of claims 1 to 13, 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.
15. A method for manufacturing a security element having a micro-optical moire 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, the arrangement of micromotif elements and the arrangement of microfocusing elements each forming, at least locally, a two-dimensional Bravais lattice, characterized in that the arrangement of micromotif elements and/or the arrangement of microfocusing elements form a Bravais lattice having the symmetry of a parallelogram lattice.
16. 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 14, and preferably comprises a carrier substrate composed of paper or plastic.

Images