SECURITY ELEMENT WITH TILT-DEPENDENT MOTIVATION AND METHOD FOR THE PRODUCTION THEREOF

Description

[0001] The invention relates to a security element for producing value documents, such as banknotes, checks or the like, which has a structure presenting a first and a second motif which change their appearance when the security element is tilted over a tilt angle range, wherein the structure has first microelements arranged according to a first pattern and presenting the first motif, and second microelements arranged according to a second pattern and presenting the second motif, and the first and second patterns are nested within one another on a surface area of ​​the security element.

[0002] The invention further relates to a method for producing a security element for value documents, such as banknotes, checks or the like, the method comprising the steps of: producing a structure on a substrate which presents a first and a second motif which change their appearance when the security element is tilted over a tilt angle range, the structure comprising first microelements which are arranged according to a first pattern and present the first motif, and second microelements which are arranged according to a second pattern and present the second motif, and the first and second patterns are nested within one another on a surface section of the security element.

[0003] Such a generic security element and such a generic manufacturing method are known from WO 2018 / 206147 A1.

[0004] From WO 2019 / 077419 A1, an optical device is known that comprises a lens array and a plurality of first and second segments arranged below the lens array. At a first viewing angle, the lens array presents a first image for viewing without presenting the second image for viewing, and at a second viewing angle different from the first viewing angle, the lens array presents the second image for viewing without presenting the first image for viewing.

[0005] WO 2017 / 184581 A1 also describes a security device with a lens arrangement and a plurality of first and second segments arranged beneath the lens arrangement. At least one first or second segment comprises one or more microstructures or one or more nanostructures configured to generate one or more colors for the first or second image.

[0006] Furthermore, WO 2018 / 219498 A1 describes a security element that combines two tilting effects. The security element consists of two different embossed structures located in two adjacent areas. First embossed structures represent a first piece of information in at least one plane, independent or at least almost independent of the viewing or tilting angle, while second embossed structures represent a second piece of information at a specific viewing or tilting angle range. At this viewing angle, the information of the first embossed structures and the information of the second embossed structures complement each other to form a single piece of information.

[0007] US Pat. No. 5,199,744 A relates to a substrate, for example, a banknote, bearing a security feature comprising, in combination, at least one embossed transitory image, for example, a latent image, and an embossed linear region. The arrangement is such that each image and each linear region can be optically recognized when the embossed region of the substrate is viewed from different angles.

[0008] The representation of achromatic motifs based on micromirrors is known from DE 102017004586 A1 or WO 2012 / 048847 A1. Further security elements, some of which use micromirrors, can be found in WO 2016 / 177470 A1, WO 2009 / 017824 A2, WO 2016 / 180522 A1, and WO 2014 / 060089 A2.

[0009] With the generic security element, it is possible to arrange the microelements - designed as micromirrors in the generic state of the art - in such a way that two motifs are only visible at a specific viewing angle on the banknote and change when the banknote is tilted, for example, switching from one motif to another. Such a change of motif is achieved, for example, with micromirrors by the mirror gradient along the perpendicular to the tilt axis having only positive values ​​in one section and only negative values ​​in another section. This approach means that when viewed from the center, usually from a vertical perspective, i.e. when the security element is not tilted, both motifs are visible simultaneously and spatially overlap. In the generic state of the art, this is used for additional effects.However, since the viewer cannot separate the two motifs from a vertical view, as is often assumed, this often results in a visually unappealing impression. Furthermore, untrained viewers who only view the security element from a narrow angle may not even notice that a change in motif would occur upon tilting, because there is no indication that tilting might reveal new information.

[0010] The object of the invention is to provide a more easily recognizable and thus ultimately forgery-proof security element and to specify a corresponding manufacturing method.

[0011] The invention is defined in the independent claims. The dependent claims relate to preferred developments.

[0012] A security element is provided for the production of value documents such as banknotes, checks or the like. It has a structure which presents a first and a second motif. The motifs change their appearance when the security element is tilted over a tilt angle range. The structure comprises first microelements and second microelements which are arranged according to a first and second pattern, respectively. The first microelements present the first motif, and the second microelements the second motif. The motifs appear in a surface area in which the first and second patterns on the security element are nested. When the security element is tilted, the appearance of the motifs changes. The microelements are designed accordingly for this purpose. The first microelements present the first motif in such a way that it is fully visible in the surface area within the tilt angle range of a specific starting tilt position.In particular, it fills the entire surface area. If the tilt position is changed, the part of the surface area in which the first motif is visible decreases with increasing tilt. When a certain final tilt position is reached, the motif is no longer visible. The second micro-elements are designed to complement this with regard to the representation of the second motif. They present the second motif in the remaining part of the first surface area in which the first micro-elements display the first motif when tilted. This remaining part of the surface area shows the second motif due to the effect of the second micro-elements. Thus, the second motif is not visible at all in the starting tilt position, since in this state the first motif generated by the first micro-elements occupies the entire surface area.As the tilt increases, the portion in which the first microelements present the first motif becomes smaller, while the remaining portion, in which the second microelements present the second motif, grows in the opposite direction. At the final tilt position, the second motif appears in its entirety in the surface area.

[0013] Instead of a global assignment of a tilt angle range for each of the two motifs, spatial sub-areas of the motifs now each have their own angle ranges. When tilting, the change between the two motifs takes place in a type of cross-fade, in which the part in which the first motif is visible becomes increasingly smaller and the rest of the surface area in which the second motif is visible grows accordingly. The two motifs are therefore never displayed in overlapping form, but their share of the surface area grows or shrinks depending on the tilt position. This makes it clear to an untrained observer in the middle position that the security element provides two motifs, because in the tilt position the observer usually sees part of the first motif and also the second motif in the remaining part of the surface area - but without the two motifs being superimposed.

[0014] This effect is particularly prominent and easily visible when only the assigned section of the respective motif is visible in each part of the surface area. This creates the impression that one motif is becoming increasingly cut off with increasing tilt, whereas the other motif becomes increasingly more complete with the tilt. The changes to the motifs therefore primarily do not involve enlarging or reducing the size of the motifs; rather, depending on the tilt position, only those sections of the motif are visible that are assigned to the remaining part or remainder of the surface area - of course, related to the entire motif, which is fully visible in the final tilt position or the starting tilt position.

[0015] The security element creates a continuous yet easily recognizable and understandable transition between the two motifs when tilted. It is possible that neither motif is visible in a border strip where the rest of the surface area borders the part of the surface area. The motifs, which displace or recede from each other when tilted, are thus separated by a kind of "neutral zone," which makes the motif change particularly striking.

[0016] It's especially preferred that the two motifs have different colors. This makes the effect particularly striking, while also solving a problem that existed in the prior art when switching between motifs of different colors: the overlap of the two differently colored motifs in the center view led to a particularly unsightly impression and made the individual motifs difficult to perceive.

[0017] The boundary along which one motif recedes and the other grows when the security element is tilted can be a moving straight line, for example, a linearly moving line or a rotating line. It is also possible for the motifs to be separated from each other by an expanding or contracting closed curve, particularly a circle. This creates a type of pumping transition.

[0018] The microelements can be implemented as micromirrors, as provided in the prior art of the generic type. Advantageously, the micromirrors of the first and / or the micromirrors of the second microelements are provided with a color coating that creates a color impression.

[0019] In advantageous designs, the color coatings of the micromirrors are formed by translucent colors. Metallizations, for example made of aluminum, silver, or an alloy such as copper and aluminum, are also possible, as are thin-film structures, in particular color-shifting thin-film structures, gold-blue, or silicon-aluminum thin films. The color coatings can also be formed by translucent colors with a metallic mirror coating, for example made of aluminum. The color coatings can represent a translucent image composed of several translucent colors, which is backed by a mirror coating, for example made of aluminum. Luminescent colors, in particular fluorescent colors with a metallic mirror coating, are also considered as color coatings. The color coatings can also be formed by structural colors, in particular nanostructures and binary structures, which are embossed on or into the micromirrors.Finally, nanoparticle paints can also be considered as color coatings, such as gold-blue particles, various effect pigments, color-shifting pigments, or supersilver. The color coatings are preferably applied directly to the micromirrors and follow their relief pattern.

[0020] Likewise, the microelements can also be realized through a combination of microimages and microlenses, or through diffractive microstructures or magnetically alignable special pigments. Combinations are possible.

[0021] Embossing processes such as those disclosed in the cited prior art for micromirror structures can be used to produce the security element.

[0022] The invention further comprises a value document, in particular a security substrate, which has a security element of the type mentioned.

[0023] The invention is explained in more detail below using exemplary embodiments with reference to the attached drawings, which also disclose features essential to the invention. These exemplary embodiments are merely illustrative and are not to be interpreted as restrictive. For example, a description of an embodiment with a large number of elements or components should not be interpreted to mean that all of these elements or components are necessary for implementation. Rather, other embodiments may also contain alternative elements and components, fewer elements or components, or additional elements or components. Elements or components of different exemplary embodiments may be combined with one another unless otherwise stated. Modifications and variations described for one of the exemplary embodiments may also be applicable to other exemplary embodiments.To avoid repetition, identical or corresponding elements in different figures are designated by the same reference numerals and are not explained more than once. The figures show: . Fig. 1 a top view of a banknote, Fig. 2 a schematic representation to explain tilt angles when viewing a security element of the banknote, Fig. 3 a schematic representation to explain the structure of a surface area of ​​the security element of the Fig. 1 und 2 , Fig. 4A-4F different representations of a first and a second motif, which are shown at different tilt angles of the security element of the Fig. 1-3 occur, and Fig. 5-8Schematic representations for various embodiments with regard to a motif change in the security element of the Fig. 1-3 .

[0024] Fig. 1 shows a top view of a banknote 2 or a precursor of such a banknote that is not yet fit for circulation. The banknote comprises a security element 4 which has a microstructure on a surface area 5 which shows two motifs. The appearance of the motifs depends on the tilt angle by which the security element is tilted when viewed. The term tilt here, as usual, refers to a tilt between the essentially flat security element 4 and the viewing direction from which a viewer looks at the security element. This relative position can be achieved by tilting the security element with a fixed viewing direction or by changing the viewing angle with the security element in a fixed position. Combinations are of course possible. For the sake of simplicity, the following assumes that the security element is tilted.

[0025] Fig. 2 shows that reference is made to the tilting about a tilting axis 6. The tilting considered here runs from a start tilting position 8 to an end tilting position 10 through a tilting angle range 11. A current tilting position 12 is therefore between the start tilting position 8 and the end tilting position 10. In the extreme case, these start and end positions are parallel to the surface of the safety element 4. In Fig. 2 It can also be seen that there is a first zone 13 beginning with the start tilt position 8 and a second zone 14 ending with the end tilt position 10. These zones are described below using the Fig. 4A und 4B explained in more detail.

[0026] The surface area 5 of the security element 4 has a plurality of first microelements 15 and second microelements 16, which are arranged interleaved in a first pattern 17 (first microelements 15) and a second pattern 18 (second microelements 16), respectively. Such an arrangement and design of microelements is known from the prior art, for example from WO 2018 / 206147 A1 or WO 2014 / 060089 A2. The microelements ensure that a first motif 20 (cf. Fig. 4A ) or a second motif 22 (cf. Fig. 4B ). The first microelements 15 present only the first motif 20, the second microelements 16 only the second motif 22. The first microelements 15 are designed such that the complete first motif 20 is only visible in the first zone 13 of the tilt angle range 11. The same applies to the second motif 22, the second microelements 16 and the second zone 14. Only in this zone is the second motif 22 fully visible. In the respective zone 8, 10, only the precisely assigned motif 20, 22 is visible, but not the other.

[0027] If you now start a tilt at the start tilt position 8, only the first motif 20 is visible (cf. Fig. 4A ), which is presented by the first microelements. If the tilt position 12 is moved out of the first zone 13, the first motif 20 begins to disappear from below in the surface area 5 and is replaced by the part of the second motif 22 located in this area. The first motif 20 is thus only visible in a part 24 of the surface area 5; in the remainder 26 of the surface area 5, the second motif 22 appears ( Fig. 4C, 4D ).

[0028] The motifs 20 and 22 preferably do not change their size; instead, only those sections of the respective motifs 20 and 22 that are assigned to these sections of the surface area are visible in part 24 and the remainder 26. If the tilt position 12 is further changed, this process increases. Fig. 4E shows approximately the center view when viewed vertically. Here, the part 24, in which the first motif 20 is still partially visible, makes up the upper half of the surface area 5, while the remainder 26, in which the corresponding part of the second motif 22 is visible, makes up approximately the lower half. When tilted even further ( Fig. 4F ) the remainder 26 occupied by the second motif 22 increases and the part 24 in which the remains of the first motif 20 can be seen decreases more and more until the tilt position 12 reaches the second zone 14 in which only the second motif 22 can be seen in the surface area 5 ( Fig. 4B ). In this way, a cross-fade occurs between the first 20 and the second motif 22.

[0029] In the Fig. 4C , 4E und 4F Between the part 24, in which the remains of the first motif 20 are visible, and the part 26, which contains the remains of the second motif 22 (with different proportions depending on the tilt position 11), there is a "neutral zone" in which neither of the two motifs can be seen. This neutral zone is formed by an edge strip 28 of the remainder 26, in which the first motif is no longer visible (since the remainder 26 is not part of the part 24 of the surface area 5), ​​but the second motif 22 is also not recognizable. This enhances the recognizability of the transition. However, it is equally possible, as Fig. 4D as a modification to the execution according to Fig. 4C shows, no edge strip 28 is provided, so that the sections of the first motif 20 in the part 24 directly adjoin the corresponding sections of the second motif 22 in the remainder 26 of the surface area 5.

[0030] The transition between the first motif 20 and the second motif 22 when tilting through the tilt angle range takes place in the embodiment of the Fig. 4A-4F along a straight line, which moves, for example, parallel to the tilt axis 6 (inclinations of up to 90° are possible). In other words, a boundary 30 between the part 24 of the surface area 5 in which the first motif 20 is visible and the remainder 26 of the surface area 5 in which the second motif 22 appears has the shape of a straight line, which also moves in a straight line. This principle is in Fig. 5 illustrated once again. Fig. 6 shows that the embodiments are not limited to this. Here, the rectilinear boundary 30 does not move along a straight line, but rotates. Fig. 7 shows a further variation in which the limit 30 rotates counterclockwise or clockwise from a dotted basic position in the form of a minute hand when the change occurs. Fig. 8 shows that the boundary 30 is not limited to straight lines, but also has the shape of a closed trajectory curve, here a circle, so that the part 24, for example, lies inside the circle and the remainder 26 is the outer area outside the circular line.

[0031] Of course, the embodiments are not limited to two motifs; this has been chosen in the described figures merely for better visibility. Three, four, or more motifs are also possible, which change in the manner described when the security element is tilted.

[0032] In addition to visually enhancing the motif change, these designs also offer additional protection against counterfeiting, as not only are two different motifs either visible or invisible, but also many intermediate views of the transition while the border 30 changes. This is difficult or impossible to counterfeit.

[0033] A further increase in security against counterfeiting is achieved when the motifs have 20, 22 different colors, which is the case in the Fig. 4A-4F indicated by different hatching. This increases the security against forgery because not only are two separate motifs with exact color registration visible, but the color registration also has a predetermined course in all intermediate views, i.e., during the change of border 30, and would therefore have to be reproduced by a forger. Furthermore, the dynamic color change achieved by changing the position of border 30 with a virtually arbitrarily designed transition contour, i.e., the shape of border 30, is significantly more striking and impressive than a purely binary change between two colors. Bezugszeichenliste

[0034] 2Banknote 4Security element 5Area 6Tilt axis 8Start tilt position 10End tilt position 11Tilt angle range 12Tilt position 13First zone 14Second zone 15First microelement 16Second microelement 17First pattern 18Second pattern 20First motif 22Second motif 24Part 26Remainder 28Edge strip 30Border

Claims

1. Security element for the production of documents of value, such as bank notes (2), cheques or the like, which has - a structure which presents a first and a second motif (20, 22) which change their appearance when the security element (4) is tilted over a tilting angle range (11), wherein - the structure has first microelements (15), which are arranged according to a first pattern (17) and present the first motif (20), and second microelements (16), which are arranged according to a second pattern (18) and present the second motif (22), and - the first and the second pattern (17, 18) are nested within each other on a surface region (5) of the security element, characterized in that - the first microelements (15) present the first motif (20) such that the first motif (20) is visible in its entirety in the surface region (5) within the tilting angle range (11) at a specific starting tilted position (8) and, when the tilted position (12) changes, is only visible in a part (24) of the surface region (5) that decreases as the tilting increases and, upon reaching a specific end tilted position (10), is no longer visible at all, and - the second microelements (16) only present the second motif (22) in the rest (26) of the surface region (5) remaining in relation to the part (24) of the surface region (5), wherein the second motif (22) is not visible at all in the surface region (5) at the starting tilted position (8) and is visible in its entirety in the surface region (5) at the end tilted position (10).

2. Security element according to Claim 1, characterized in that the first microelements (15) present the first motif (20) such that, upon tilting, only the portion of the first motif (20) that is assigned to the part (24) of the surface region (5) is visible, and in that the second microelements (16) present the second motif (22) such that, upon tilting, only the portion of the second motif (22) that is assigned to the rest (26) of the surface region (5) is visible.

3. Security element according to one of the above claims, characterized in that the first and the second microelements (15, 16) present the motifs (20, 22) such that, upon tilting, neither of the two motifs (20, 22) is visible in an edge strip (28) of the rest (26) of the surface region (5) that borders on the part (24) of the surface region (5).

4. Security element according to Claim 3, characterized in that the edge strip that borders on the part (24) of the surface region (5) forms a neutral zone which separates the motifs from each other.

5. Security element according to one of the above claims, characterized in that the two motifs (20, 22) are of different colours.

6. Security element according to one of the above claims, characterized in that a boundary (30) between the part (24) and the rest (26) of the surface region (5) is a straight line that moves as the tilting increases or in that a boundary (30) between the part (24) and the rest (26) of the surface region (5) is a closed curve, in particular a circle, which becomes larger as the tilting increases.

7. Security element according to one of the above claims, characterized in that the first and / or second microelements (15, 16) have micromirrors.

8. Security element according to Claim 7, characterized in that the micromirrors of the first and / or the second microelements are provided with an ink coating that produces a colour impression, wherein the ink coatings of the micromirrors are formed in particular by glazing inks, by metallizations, by thin-film structures, by glazing inks backed with a metallization, by luminescent inks with a metallic mirror coating, by structural inks, in particular by nano and binary structures, and / or by nanoparticle inks.

9. Security element according to one of the above claims, characterized in that the first and / or second microelements (15, 16) have microimages and microlenses.

10. Security element according to one of the above claims, characterized in that the first and / or second microelements (15, 16) have diffractive microstructures.

11. Document of value with a security element (4) according to one of Claims 1 to 10.

12. Method for producing a security element for documents of value, such as banknotes (2), cheques or the like, wherein the method has the steps of: - producing a structure on a substrate presenting a first and a second motif (20, 22) which change their appearance when the security element (4) is tilted over a tilting angle range (11), wherein - the structure has first microelements (15), which are arranged according to a first pattern (17) and present the first motif (20), and second microelements (16), which are arranged according to a second pattern (18) and present the second motif (22), and - the first and the second pattern (17, 18) are nested within each other on a surface portion (5) of the security element, characterized in that - the first microelements (15) present the first motif (20) such that the first motif (20) is visible in its entirety in the surface region (5) within the tilting angle range (11) at a specific starting tilted position (8) and, when the tilted position (12) changes, is only visible in a part (24) of the surface region (5) that decreases as the tilting progresses and, upon reaching a specific end tilted position (10), is no longer visible, and - the second microelements (16) only present the second motif (22) in the rest (26) of the surface region (5) remaining in relation to the part (24) of the surface region (5), wherein the second motif (22) is not visible at all in the surface region (5) at the starting tilted position (8) and is visible in its entirety in the surface region (5) at the end tilted position (10).

13. Method according to Claim 12, characterized in that a security element (4) according to Claims 2 to 10 is produced.