EP3793841A1

EP3793841A1 - Optically variable security element having reflective area

Info

Publication number: EP3793841A1
Application number: EP19726572.1A
Authority: EP
Inventors: Raphael DEHMEL; Christian Fuhse; Kai Herrmann SCHERER; Maik Rudolf Johann Scherer
Original assignee: Giesecke and Devrient Currency Technology GmbH
Current assignee: Giesecke and Devrient Currency Technology GmbH
Priority date: 2018-05-18
Filing date: 2019-05-16
Publication date: 2021-03-24
Anticipated expiration: 2039-05-16
Also published as: CN111757812A; WO2019219237A1; EP3793841B1; DE102018004052A1; CN111757812B

Abstract

The invention relates to an optically variable security element (12) for securing valuable objects, having a substrate (22) with a reflective area (20), the extent of which defines an x-y plane and a z axis perpendicular thereto, wherein the reflective area (20) contains a plurality of reflective portions (30), and each portion (30) has multiple identically oriented reflective facets (32), and an orientation of each facet (32) relative to the x-y plane is defined by indicating its normalised normal vector (n). The projection of the normal vector into the x-y plane defines an inclination direction (r) of the facet. The length (L) of a facet is its dimension in the inclination direction; the width (B) of a facet is its dimension perpendicular to the inclination direction in the x-y plane, and the height (H) of a facet is its dimension in the z direction. According to the invention, the identically oriented facets (32) in the reflective portions (30) are arranged with decreasing length (L) and decreasing height (H) in their common inclination direction (r).

Description

Optically variable security element with reflective surface area

The invention relates to an optically variable security element for securing valuables, comprising a support having a reflective surface area which contains a multiplicity of reflective subregions, each subarea having a plurality of identically oriented reflective facets.

Data carriers, such as security or identification documents, or other objects of value, such as branded articles, are often provided with security elements for securing purposes, which permit a verification of the authenticity of the data carriers and at the same time serve as protection against unauthorized reproduction.

Security elements with a viewing angle-dependent or three-dimensional appearance play a special role in the authentication of authenticity, since they can not be reproduced even with the most modern copying machines. For this purpose, the security elements are equipped with optically variable elements which give the viewer a different image impression under different viewing angles and, for example, show a different color or brightness impression and / or another graphic motif depending on the viewing angle. In the prior art, optically variable effects, for example, motion effects, pump effects, depth effects, relief effects or flip-effects, which are realized with the aid of holograms, microlenses or micromirrors, are described.

Hologram-based optically variable elements are widely used, but their conspicuousness and recognizability are hampered by their relatively low brilliance and diffractive color splitting of the reflected light. In addition, because of their relatively easy manufacturability, they offer less protection against forgery than microlens sen or micromirror structures based security elements. The implementation of the above-mentioned optically variable effects with the help of microlenses allows illumination-independent good visibility. However, microlens structures usually require a large layer thickness of the security element. The fabrication of microlens-based authenticity features also involves some technical challenges: in the motif layer under the lens layer, only a few micrometres motifs with high quality must be displayed, and both the lens layer and the motif layer must be produced with high grid fidelity become. In practice, only periodic patterns of symbols whose size is limited to a few millimeters can currently be generated. The representation of the symbols is often slightly distorted and blurred, which lowers the recognition value of the security element.

An attractive variant is therefore the implementation of optically variable effects with the help of micromirrors, which is technologically less complex and allows large-area and sharp subjects in flat security elements. For good visibility and an attractive visual impression, the brightness and brilliance of the micromirror structures are particularly important.

Micromirror arrangements are currently produced in security elements, for example, by subdividing a desired effect area into equal pixels of a size of, for example, 20 μm x 20 μm, assigning a mirror pitch to each pixel, thus determining in which way the micromirrors of the pixel should be tilted relative to a substrate plane, and that the pixels are then filled with wedge-shaped micro mirror rules of the respective mirror slope. The micromirrors have usually a solid base, typically 10 gm x 10 pm. An example of a similar design is described in document EP 2390 106 B1. A disadvantage of such designs, however, is that the periodic arrangement of the micromirrors often leads to undesirable diffractive effects and colored light reflections that disturb the actually desired achromatic appearance of the micromirror arrangement.

Aperiodic arrangements of micromirrors are also known and described, for example, in document WO 2012/055505 A1. In the case of aperiodic arrangements, diffractive effects are largely avoided; a larger number of micromirrors is usually required to fill a given surface area, resulting in a lower area ratio of smooth mirror surfaces to (in practice) rounded edge regions and thus to lower brilliance can lead.

Based on this, the present invention seeks to provide an optically variable security element of the type mentioned, which avoids the disadvantages of the prior art, and in which in particular a high anti-counterfeiting security are associated with high brightness and brilliance.

This object is solved by the features of the independent claims. Further developments of the invention are the subject of the dependent claims.

In a generic security element, the extent of the reflective surface area defines an xy plane and a z-axis perpendicular thereto. The orientation of each facet relative to the xy plane is determined by the indication of its normalized normal vector, where the projection of the normal vector into the xy plane defines a tilt direction of the facet. The length of a facet is its dimension in the direction of inclination, the width of a facet its dimension perpendicular to the inclination direction in the xy plane, and the height of a facet its dimension in the z-direction. According to the invention, it is now provided in such a safety element that in the reflective subregions the identically oriented facets are arranged along their common inclination direction with decreasing length and decreasing height.

In this way, a facet arrangement is created which can produce a desired appearance of the surface area with high brightness and brilliance and yet is never periodic. Due to the lack of periodicity, the arrangement is more difficult to adjust and therefore has a high security against counterfeiting. At the same time disturbing diffractive effects and resulting colored light reflections are avoided, whereby a larger amount of light is available for the desired reflection. Compared to conventional aperiodic designs, the now proposed arrangement has the advantage that a small number of facets for filling a portion is required. Especially with shallow facet slopes, large contiguous areas with high brightness are created. In addition, mutual shading effects are minimized by the size of the chain decreasing in the direction of inclination.

In a preferred embodiment, the identically oriented facets are arranged at least in a subset of the subregions, in each case along their common seed inclination direction with a length and height that are about the same constant factor. In concrete terms, the height and length of the following facet, which is in the direction of inclination (k + 1), results from the height and length of the facet k-th in the direction of inclination H _{k + i} = f * H _k and L _{k + i} = f * L _k

with a factor f less than 1, which is constant for the entire subarea. The constant factor can also be the same for all subregions of the subset mentioned.

Advantageously, the constant factor is between 0.6 and 0.95, preferably between 0.75 and 0.85. In an advantageous embodiment, the identically oriented facets are even arranged in all subareas in the manner mentioned.

In a further, likewise advantageous embodiment, the identically oriented facets are arranged at least in a subset of the subregions in each case along their common inclination direction with a height decreasing from facet to facet by a constant height difference. In concrete terms, the height and length of the following facet, which is inclined in the direction of inclination (k + 1), are given by the height and length of the facet k k in the direction of inclination, by H _{k + i} = H _k - D. The length of each facet results with the angle of inclination a from its height to L _k = H _k / tan (a). The height difference D is constant for the entire subarea, but it may even be the same for all subareas of the subset mentioned.

Advantageously, said constant height difference is between 50 nm and 400 nm, preferably between 80 nm and 150 nm. In an advantageous design, the identically oriented facets are arranged in all subregions in the manner mentioned.

In the described variants with a constant factor or constant height difference, the heights of the facets can be additionally varied by a small, in each case substantially randomly selected height variation, wherein the additional substantially random height variation is advantageously less than 5%, in particular less than 2% of the initial height before the height variation. The length of the facet is then adjusted accordingly to keep the inclination angle constant.

The chosen formulation, according to which the heights of the facet vary by a substantially randomly chosen height variation, takes into account the fact that a random variation can also be realized for example by means of computer-generated "random numbers" which are strictly deterministic ,

The height of the facets of the reflective surface area preferably does not exceed a maximum height H _max which is less than 20 μm, preferably 10 μm or less, particularly preferably 5 μm or less. This can be achieved, for example, by the fact that in each case the first facet of each subarea, which is at the rear in the direction of inclination, is formed with a height which is less than or equal to the maximum height.

The equally oriented facets advantageously adjoin one another directly along the common inclination direction. Alternatively, the facets may be arranged in the direction of inclination also with a small distance in the x-y plane is. The distance between the facets is advantageously less than 10%, in particular less than 5%, of the average length of the two adjoining facets.

The reflective subregions expediently have a length in the common direction of inclination of the facets of less than 300 μm, preferably less than 100 μm, particularly preferably between 20 μm and 100 μm. The reflective subregions can be square, rectangular, but also with be formed of any outline. In particular, at least some of the reflective subareas may be formed with an outline in the form of a motif, in particular in the form of characters or symbols. In the case of a general outline, the largest dimension of the partial regions in the plane is expediently below 300 gm, preferably below 100 gm, particularly preferably between 20 gm and 100 gm.

The width of the facets preferably each occupies the maximum available width of a partial area. The facet shape advantageously follows the edge of the section, which can also run obliquely or curved.

Advantageously, eight or less, preferably five or less, in particular two, three or four facets are arranged in the reflective subregions along the common direction of inclination.

The reflective facets are advantageously oriented in such a way that the reflective area can be perceived by a viewer as a curved, in particular continuously curved surface, preferably as a surface curved in two spatial directions, in particular continuously curved. Furthermore, it is advantageously provided that the reflective facets are oriented in such a way that the reflective surface area produces a movement effect, pump effect, depth effect, relief effect and / or flip effect when tilting or rotating the security element.

Advantageously, the reflective facets have a metallic or semiconducting coating, a high refractive index coating or a coating with a color-shifting layer. The color-shifting layer can in particular be designed as a thin-layer system or thin-film interference coating. to be. It can be z. B. a layer sequence metal layer - dielectric layer - metal layer or a layer sequence of at least three dielectric layers, wherein the refractive index of the middle layer is less than the refractive index of the other two layers, realized. As the lektrisches material can, for. As ZnS, Si0 ₂ , T1O2, MgF ₂ can be used.

The color-shifting layer can also be formed as an interference filter, thin semitransparent metal layer with selective transmission by plasma resonance effects, nanoparticles, etc. Likewise, the color-shifting layer can be realized as a diffractive relief structure or sub-wavelength gratings.

The reflective surface region may alternatively or additionally be provided with a liquid crystal coating, preferably with a full-area cholesteric liquid crystal coating.

The reflective facets represent substantially planar surface elements inclined against the x-y plane, the expression "essentially" taking account of the fact that in production, due to production, it is not possible to produce perfectly flat surface elements. The facets of a subarea are all the same orientation, with small variations in the tilt angle of a few percent possible. Preferably, the inclination angles of a subregion are equal to less than 3%, preferably less than 2%, in particular less than 1%.

The invention also includes a data carrier with a security element of the type described. The data carrier may in particular be a value document, such as a banknote, in particular a paper banknote, a polymer banknote or a film composite banknote, for a share, a bond, a certificate, a voucher, a check, a high-quality entrance ticket, but also to act as an identification card, such as a credit card, a bank card, a cash card, an authorization card, a personal ID card or a pass personalization page.

The invention further includes a method for producing a security element of the type described above, in which a carrier is provided and provided with a reflective surface region whose extent defines an xy plane and a z axis perpendicular thereto, the reflective surface region is formed with a multiplicity of reflective subareas and each subarea having a plurality of identically oriented reflective facets, an orientation of each facet relative to the xy plane being determined by the indication of its normalized normal vector, the projection of the normal vector into the xy plane The direction of inclination of the facet is defined, the length of a facet is its dimension in the inclination direction, the width of a facet is its dimension perpendicular to the inclination direction in the xy plane, and the height of a facet is its dimension in the z-direction, and the identically oriented facets in the reflective subregions along their common inclination direction can be arranged with decreasing length and decreasing height. Further exemplary embodiments and advantages of the invention will be explained below with reference to the figures, in the representation of which a representation true to scale and proportion has been dispensed with in order to increase the clarity.

Show it:

1 shows a schematic representation of a banknote with an optically variable security element according to the invention in the form of a glued transfer element,

Fig. 2 is an illustration of the coming of the three-dimensional

3 is a perspective view of a reflective portion filled with five facets lying behind one another, FIG.

Fig. 4 is an illustration of one of the facets of Fig. 3 in detail to

Illustration of the definition of the variables describing the orientation and size of the facets

Fig. 5 in perspective view to be filled with facets

6 shows a vertical plan view of the surface area and partial area of FIG. 5, and FIG 7 shows the height profile of the relief structure given by the facets of the partial area in a side view from the direction VII of FIG. 6.

The invention will now be explained using the example of security elements for banknotes. FIG. 1 shows a schematic representation of a banknote 10 with an optically variable security element 12 according to the invention in the form of a glued-on transfer element. It should be understood, however, that the invention is not limited to transfer elements and banknotes, but can be used with all types of security elements, such as labels on goods and packaging or in the security of documents, ID cards, passports, credit cards, health cards and like. In the case of banknotes and similar documents, in addition to transfer elements, for example, security elements designed as security threads or security strips may be considered.

The security element 12 shown in FIG. 1 is itself formed extremely flat with maximum height differences of about 10 gm, but still conveys to the viewer a clear three-dimensional impression of the depicted motif of a value 14 of high brightness and brilliance apparently bulged out of the plane of the banknote 10 , For this purpose, the security element 12 contains a reflective surface area 20 whose extension defines an x-y plane which here coincides with the surface of the banknote 10. The z-axis is perpendicular to the x-y plane, so that the coordinate system formed by the three axes forms a legal system.

The particular structure of optically variable security elements according to the invention will now be explained in more detail with reference to FIGS. 2 to 4. First FIG. 2 illustrates the formation of the three-dimensional appearance of the security element 12, the reference numeral 40 representing the surface, which is perceived by the viewer when viewing the security element 12, curved in two spatial directions, for example the value 14 of FIG.

In the carrier 22 of the security element 12 is not the perceived by the viewer curved surface 40 itself formed, but rather a relief structure 24 having a plurality of small reflective portions 30, of which in the detail of Fig. 2 four portions 30-1 to 30-4 are shown. The partial regions 30 each have a plurality of reflective facets 32, which are each formed with the same orientation within a partial region 30.

For a more detailed explanation, FIG. 3 shows a perspective view of a reflective subregion 30 which is filled with five successive facets 32-1 to 32-5. The facets 32-1 to 32-5 represent substantially planar surface elements inclined against the xy plane. In Fig. 4, one of the facets 32 of Fig. 3 is shown in more detail to define the definition of the orientation and size of the facets To illustrate sizes.

. Referring first to Figure 4, the orientation of each facet 32 by specifying their normalized normal vector n = _(x n, _y n, n _z) | n \ = 1 and positive z-component determined. The projection of the normal vector n into the xy plane of the surface area 20 defines an inclination direction r in the xy plane. The direction of inclination r represents a vector lying in the xy plane, the direction of which indicates the direction in which perpendicularly incident light is reflected by the facet 32. If the normal If the gate n should be located perpendicular to the xy plane in a subregion, the direction of inclination of this subregion can be selected arbitrarily in the xy plane for the construction explained below.

The dimensions of the facets 32 are now defined in each case with respect to their inclination direction r, as illustrated in FIG. 4. The length L of a facet 32 is its dimension in the direction of inclination, the width B of a facet its dimension perpendicular to the direction of inclination in the x-y plane, and the fleas of a facet its dimension in the z-direction. As can be readily seen from Fig. 4, the inclination angle a of a facet 32 against the x-y plane is linked to the length and height of the facet via the relationship tan (a) = H / L.

Returning to the representation of FIG. 2, the facets 32 of the area 20 in order to simulate the reflection behavior of the curved surface 40 are oriented in each subarea 30 in such a way that their normal vectors lie there beyond the extent of the subarea 30 average local normal vector N corresponds to the curved surface 40.

In the exemplary embodiment shown, the subregions 30 are designed with a square outline, but in general they can also have any other contours, as illustrated below in the exemplary embodiment of FIGS. 5 to 7. The edge length K or the maximum dimension of the subareas 30 in the x-y plane is below 300 gm and is in particular in the range from 20 gm to 100 gm.

Length L and width B of the facets 32 are above 3 gm, preferably above 5 gm, and the height of the facets is between 0 and 10 gm, preferably between 0 and 5 gm, so that the entire reflective surface is chenbereichs height differences of up to 10 mm, which are imperceptible to the naked eye.

Since the geometric reflection condition "angle of incidence equal failure angle" for the reflection of directed light 42 (FIG. 2) depends only on the local orientation of the normal vector of the reflective surface 40, 24 and the subregions 30 are also very small and thus Even if they do not appear, the reflective area 20 with the relief structure 24 exhibits substantially the same reflection properties as the three-dimensional area 40 to be imitated and therefore produces the pronounced three-dimensional impression of the imitated area 40 in the viewer despite its small height differences.

The peculiarity of the present invention consists in the particularly clever arrangement of the facets 32 in the subregions 30, which leads to a high brightness and brilliance of the surface region 20.

Since the facets 32 in the subregions 30 are in each case oriented identically, ie have the same inclination angle a and the same normalized normal vector, the inclination direction r projected into the xy plane is the same for all facets 32 of a subarea 30, so that in each subarea of one common tilt direction of the facets can be spoken.

As shown in Figs. 2 and 3, the like oriented facets 32 and 32-1 to 32-5, respectively, are disposed in the reflective portions 30 along their common inclination direction r with decreasing height H and decreasing length L. For this purpose, it can be provided, for example, that the first (rearmost) facet 32-1 of a subarea 30 in the direction of inclination r has desired maximum height H _max and the subsequent in the direction of inclination r subsequent facets 32 each have 80% of the height and 80% of the length of the previous facet. Since the height and length of the facets 32 always change by the same factor, the angle of inclination, which is given by tan (a) = H / L, remains unchanged.

In order to specify a concrete numerical example, the desired inclination angle for a surface area a = 30 ° and the first facet 32-1 have a height of Hi = 10 μm as the maximum desired height. Its length Li then results from the angle of inclination a = 30 ° with the relationship Li = Hi / tan (a) to Li = 17.32 pm. The second facet 32-2 directly adjoins the first facet 32-1 in the tilt direction, but only has a height of H ₂ = 0.8 * Hi = 8 pm. Its length defined by the angle of inclination a is then L ₂ = H ₂ / tan (a) = 13.86 pm, whereby automatically L ₂ = 0.8 * Li also applies by construction. The third facet 32-3 directly adjoins the second facet 32-2 in the direction of inclination, but has only a height H ₃ = 0.8 * H ₂ = 6.4 pm and a length L ₃ given by the inclination angle a H ₃ / tan (a) = 11.08 pm, where again L ₃ = 0.8 * L ₂ . Analogously, the further facets 32-4 and 32-5 have heights of H ₄ = 5.12 pm and Hs = 4.1 pm and associated lengths L ₄ and Ls, respectively. The sum of the lengths Li to Ls corresponds to the edge length K of the portion 30. The width of the Facet th 32-1 to 32-5 is constant in the embodiment and corresponds to the edge width K of the square portion 30th

Such an arrangement is nowhere periodic and therefore has a high imitation security and by the absence of disturbing dif fr active effects and colored light reflections also a high brilliance. Compared to conventional aperiodic designs, the brilliance of the facet arrangement is markedly increased, since, in particular, at small angles of inclination a, a large amount is added. connected surfaces are possible. The facet size, which decreases in the direction of inclination, also minimizes mutual shading effects.

The arrangement of the facets 32 and the choice of the facet parameters for a general subregion 30 having an arbitrary contour will now be described in more detail with reference to FIGS. 5 to 7. First, FIG. 5 shows a perspective view of a partial region 30 to be filled with facets 32 within a reflective surface region 20. The normal normal vector N of the arched surface 40 to be represented results from the normalized normal vector desired for the partial region 30. From this one obtains by projection into the xy-plane the common inclination direction r for all facets of the sub-region 30. The angle between the vectors n and r is the complementary angle to the inclination angle a of the facets, thus complements this 90 °. The inclination angle a is in the partial area 30 by way of example a = 30 °.

The facets 32 are now to be arranged along a straight line 50 in the direction of inclination r from back to front with decreasing height and decreasing length. The terms 'back' and 'front' refer to the direction of the vector r and are therefore always clearly defined. With reference to Fig. 6, which shows the surface portion 20 with the portion 30 in senkrech ter supervision, two tangents 52 are initially applied to the contour 34 of the portion 30, which are perpendicular to the straight line 50 and whose distance is the length L. _{ges of} the portion 30 in the direction of inclination r indicates. In the exemplary embodiment, this distance is by way of example L _ges = 55 gm.

Now, a desired maximum height for the facets will be specified, such as Hma _x = 10 pm, as well as a scaling factor for the decreasing facet size. For example, £ = 0.8. Intestine is a first facet with Fli = Fl _max selected and the associated length Li = Hi / tan (30 °) = 17.32 pm determined. A second facet with H ₂ = f * Hi and L ₂ = f * Li is added, which has the same inclination angle a as the first facet due to the choice of height and length values, tan (a) = H ₂ / L ₂ = HL / LI. In the exemplary embodiment, H ₂ = 8 gm and L ₂ = 13.86 gm.

Then, as long as each of the scaling factor f th reduced Facet added to reach the sum of the facet lengths of the length of the Teilbe- Reich L _ges or higher. In the exemplary embodiment, this is the case after the addition of the fifth facet, since the sum of the facet lengths is then

Lsum = 17.32 gm + gm + 13.86 11.08 + 8.87 gm gm gm + 7.09 = 58.22 is gm and thus the length L _ges = 55 exceeds gm.

In order to accommodate this facet arrangement in the subarea 30, the lengths and heights are scaled to the desired overall length L _tot , and for that purpose all the lengths and heights are multiplied by a passer factor P = L _ges / L _Sum , in the present case P = 55/58, 22 is. This ensures that a) the facet arrangement in the direction of inclination r exactly fits in the Teilbe, since the scaled sum of the facet lengths is exactly L _ges , b) the maximum height H _{max is} not exceeded, since the Passerfaktor after construction is always less than or equal 1 is, and

c) the inclination angles a are not changed by the scaling, since length L and height H are multiplied by the same passer factor, so that the tilt angle given by the quotient (P * H) / (P * L) = H / L remains unchanged , In the mentioned embodiment, for example, the height of the first facet 32-1 after scaling is H'i = P * Hi = 9.45 pm and its length is L i = P * Li = 16.36 pm. The sizes of the further facets 32-2 to 32-5 are correspondingly smaller by a factor of 0.8 than the preceding facet, ie H ' ₂ = 7.56 pm and L' ₂ = 13.09 pm, etc. All facets have an inclination angle of a = 30 ° and the sum of the facet lengths is by the scaling just L _ges = 55 pm.

With reference to FIG. 6, a rectangle is filled with the scaled facets 32-1 to 32-5, which is defined by the two already mentioned tangents 52 and by two tangents 54 to the partial region 30 parallel to the straight line 50. The facets are then limited to the interior of the portion 30 be, so that only the portion 30, but this is completely filled with the be written facets. In Fig. 6, the facets 32-1 to 32-5 for illustration from behind (top left in Fig. 6) to the front (bottom right in Fig. 6) are shown alternately hatched.

The height profile of the given by the facets 32-1 to 32-5 Reli efstruktur 24 is illustrated in Fig. 7, which is a side view of the portion 30 from VII direction of Fig. 6, ie in the direction of inclination r and along the Ge straight 50 of FIG 6 shows. Also drawn in is the normalized normal vector n of the subregion 30, which represents the starting point for the construction of the facets 32-1 to 32-5.

In the height profile of the relief structure 24, in addition to the respective dimension of the facets 32-1 to 32-5 in the z-direction, their absolute height with respect to the xy plane also changes. In this case, the facets in the surface of the carrier are formed such that the lowest points or the minimum height values of all facets lie in a plane (parallel to the xy plane) (the Facets 32-1 to 32-5 represent substantially planar surface elements inclined to the xy plane).

On the other hand, if the respective peak values or the maximum (absolute) height values of all facets 32-1 to 32-5 of the subarea 30, relative to the xy plane, are all at the same level or parallel to the xy plane Plane, which corresponds to the viewing of the relief structure 24 shown in FIG. 7 (or the reflective interface formed by the facets 32-1 to 32-5) from the rear side, are the facets 32-1 to 32-5 along their joint inclination direction arranged with increasing length and increas ing level. Even with such an arrangement, mutual shading effects are minimized.

LIST OF REFERENCE NUMBERS

10 banknote

12 security element

14 curved value

20 reflective surface area

22 carriers

24 relief structure

30 subareas

30-1 to 30-4 sections

32 facets

32-1 to 32-5 facets

34 outline

40 arched area

42 incident light

50 Straight

52 tangents

54 tangents

Claims

Patent claims

1. An optically variable security element for hedging Wertge objects, with a carrier having a reflective surface area whose extension defines an xy plane and a z-axis perpendicular thereto, wherein the reflective area contains a plurality of reflective Teilberei surfaces and each subarea more , an orientation of each facet relative to the xy plane is determined by the indication of its normalized normal vector, the projection of the normal vector into the xy plane defines an inclination direction of the facet, the length of one Facet their dimension in the direction of inclination, the width of a facet their dimension perpendicular to the direction of inclination in the xy plane, and the height of a facet is their dimension in the z-direction, characterized in that in the reflective portions of the same oriented facets ent long their common inclination direction with decreasing length e and decreasing height are arranged.

2. Security element according to claim 1, characterized in that the identically oriented facets at least in a subset of Teilberei- are each arranged along their common direction of inclination with a decreasing by the same constant factor length and height.

3. Security element according to claim 2, characterized in that the constant factor is between 0.6 and 0.95, preferably between 0.75 and 0.85.

4. The security element according to claim 1, characterized in that the identically oriented facets are arranged at least in a subset of the subregions in each case along their common inclination direction with a height decreasing from facet to facet by a constant height difference.

5. A security element according to claim 4, characterized in that the constant height difference between 50 nm and 400 nm, preferably between 80 nm and 150 nm.

6. The security element according to claim 1, characterized in that the height of the facets of the reflective area does not exceed a maximum height H _max which is less than 20 μm, preferably 10 μm or less, particularly preferably 5 μm or less is.

7. Security element according to at least one of claims 1 to 6, characterized in that the identically oriented facets adjoin one another directly along the common direction of inclination.

8. A security element according to at least one of claims 1 to 7, characterized in that the reflective subregions in the common Seeds direction of the facets have a length below 300 gm, preferably below 100 gm, more preferably between 20 gm to 100 gm have.

9. A security element according to at least one of claims 1 to 8, characterized in that the identically oriented facets are formed with a width, each occupying the maximum, available width of the portion, wherein the facet shape advantageously follows the edge of the portion.

10. A security element according to at least one of claims 1 to 9, characterized in that eight or less, preferably five or less, in particular two, three or four facets are arranged in the reflective subregions along the common direction of inclination.

11. A security element according to at least one of claims 1 to 10, characterized in that at least a part of the reflective Teilberei- surface with an outline in the form of a motif, in particular in the form of Zei chen or symbols is formed.

12. The security element according to claim 1, characterized in that the reflective facets are perceptible to a viewer as an arched, in particular continuously curved surface, preferably as an arched in two spatial directions, in particular continuously vaulted te surface is perceptible.

13. A security element according to at least one of claims 1 to 12, characterized in that the reflective facets are oriented, when the tilting or rotation of the security element, the reflective surface area produces a movement effect, pump effect, depth effect, relief effect and / or flip effect.

14. A security element according to at least one of claims 1 to 13, characterized in that the reflective facets have a metallic or semiconductive coating, a high refractive index coating or a coating with a color-shifting layer.

15. A security element according to at least one of claims 1 to 14, characterized in that the reflective surface area is provided with a liq sigkristallbeschichtung, preferably with a full-surface cholesteric liquid crystal coating.

16. Disk with a security element according to at least one of

Claims 1 to 15.

17. A method for producing an optically variable security element according to any one of claims 1 to 15, wherein a carrier is provided and provided with a reflective surface area whose extension defines an xy plane and a z-axis perpendicular thereto, - wherein the reflective Surface area with a variety of reflective

Subareas and each subarea is formed with a plurality of identically oriented reflective facets, where an orientation of each facet relative to the xy plane is determined by the specification of its normalized normal vector, the projection of the normal vector into the xy plane defines a tilt direction of the facet, the length of a facet defines its dimension in the tilt direction, the width of one facet Facet their dimension perpendicular to

Direction of inclination in the x-y plane, and the height of a facet is its dimension in the z-direction, the equally oriented facets in the reflective portions are arranged along their common inclination direction with decreasing length and decreasing height.