Optical security element with effect regions
Patent Information
- Application Number
- EP2023789222
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-09-15
- Filing Date
- 2023-09-13
- Publication Date
- 2025-07-23
AI Technical Summary
Conventional optical security elements with multiple effect areas suffer from register fluctuations and visual attractiveness issues due to sharp boundaries, making it difficult to distinguish between originals and counterfeits.
An optical security element with at least two effect areas that border each other along a non-smooth boundary line, featuring a transition area where one area is formed by micro mirrors and the other by diffractive structures, such as holograms, with a boundary design that has projections and incisions below the human eye's resolution limit, creating a smooth transition between effects.
Enhances anti-counterfeit security and visual appeal by concealing register fluctuations and providing a seamless merge of optical effects, preventing the use of sharp boundaries as reference points for positional deviations.
Smart Images
Figure 1.1
Abstract
Description
[0001] Optical security element with effect areas
[0002] The invention relates to an optical security element for protecting valuables, comprising at least two effect areas for generating different optical effects. The invention also relates to a data carrier comprising such a security element, as well as a method for producing such a security element.
[0003] Data storage media, such as valuables or identification documents, but also other valuable items, such as branded goods, are often provided with security elements for security purposes. These elements allow the authenticity of the data storage media to be verified and at the same time serve as protection against unauthorized reproduction.
[0004] A combination of several different optical effects is often used to increase the counterfeit security of an optical security element. If effect areas with different optical effects border on one another, a boundary line is defined between the effect areas. This boundary line can serve as a reference for the viewer for register fluctuations that arise during other production processes. Such fluctuations can be irritating to the viewer. In addition to reducing visual appeal, the counterfeit security of the optical security element is also reduced, as counterfeits in particular often have register errors, making it more difficult to reliably distinguish between originals and counterfeits when register fluctuations occur in originals.
[0005] Based on this, the invention is based on the object of providing an optical security element of the type mentioned above with a high degree of forgery protection and an attractive visual appearance. This object is achieved by the features of the independent claims. Further developments of the invention are the subject of the dependent claims.
[0006] The invention provides an optical security element for securing valuables, with at least two effect regions for generating different optical effects, wherein the effect regions adjoin one another along a boundary line, and at least one of the two effect regions is formed by a micro-mirror region with directionally reflecting micro-mirrors.
[0007] The boundary between the two aforementioned effect areas is not smooth-edged, creating a transition area between the two effect areas along the boundary line. When viewed from the outside, the optical effect of the first effect area seamlessly transitions into the optical effect of the second effect area. The optical security element therefore has no sharp boundary between the aforementioned effect areas, meaning that, for example, there is no fixed visual reference point for the correct position of a (structural) feature created in a different production step.
[0008] In an advantageous embodiment, the at least two effect regions are formed by micromirror regions with directionally reflecting micromirrors and different micromirror effects. In particular, one of the micromirror regions can be metallized and another of the micromirror regions can be unmetallized, for example, demetalized after metallization. In another, equally advantageous embodiment, one of the effect regions is formed by a micromirror region with directionally reflecting micromirrors, and another of the effect regions is formed by a diffractive relief structure, in particular a hologram, a holographic grating image, or a hologram-like diffraction structure.
[0009] In all designs, it can advantageously be provided that the micromirror region(s) each contain non-diffractive mirrors and preferably plane mirrors, concave mirrors and / or Fresnel-type mirrors.
[0010] The aforementioned non-smooth-edged boundary line is advantageously serrated, notched, toothed, lobed, indented, or wavy. A boundary line between two effect areas that has tapered projections and tapered indentations is referred to as serrated; a boundary line with rounded projections and tapered indentations is referred to as notched; a boundary line with tapered projections and round indentations is referred to as toothed; and a boundary line with rounded projections and round indentations is referred to as lobed, indented, or wavy, depending on the extent of the projections and indentations extending into the adjacent effect area. A large extension, where the projections or incisions extend more than 5 mm into the adjacent effect area, is referred to as lobed, a medium extension, where the projections or incisions extend 0.5 mm to 5 mm into the adjacent effect area, is referred to as indented and a small extension, where the projections or incisions extend more than 5 mm into the adjacent effect area, is referred to as indented.Incisions extending less than 0.5 mm into the adjacent effect area are referred to as wavy.
[0011] Advantageously, the effect areas extend into one another along the boundary line. In an advantageous refinement, one of the effect areas forms an outer effect area that surrounds another of the effect areas, which forms an inner effect area, and the boundary line is formed by the outline of the inner effect area.
[0012] In all designs, it can advantageously be provided that the boundary line of the two effect areas is not smooth-edged on a length scale below the resolution limit of the human eye.
[0013] In an advantageous embodiment, the non-smooth-edged boundary line has a plurality of projections with sharp changes in direction on a length scale below the resolution limit of the human eye. The projections advantageously have widths and spacings below the resolution limit of the human eye, preferably below 150 μm, in particular below 100 μm.
[0014] In an advantageous embodiment, the projections are arranged uniformly, in particular periodically, along the boundary line, wherein the period length is below 300 gm, preferably below 200 gm, particularly preferably between 10 and 100 gm.
[0015] In another, likewise advantageous embodiment, the projections are not arranged uniformly along the boundary line, preferably with a varying spacing, the mean value of which is below 300 μm, preferably below 200 μm, particularly preferably between 10 and 100 μm. The height of the projections is expediently between 50 μm and 50 mm, preferably between 50 μm and 10 mm, particularly preferably above the resolution limit of the human eye and in particular between 0.5 mm and 5 mm. Accordingly, the width of the transition region is expediently between 50 μm and 50 mm, preferably between 50 μm and 10 mm, particularly preferably above the resolution limit of the human eye and in particular between 0.5 mm and 5 mm.
[0016] The invention also includes a data carrier with an optical security element of the type described. The data carrier can be, in particular, a value document, such as a banknote, in particular a paper banknote, a polymer banknote or a composite film banknote, a share, a bond, a certificate, a voucher, a cheque, a seal, a tax stamp, a high-value admission ticket, but also an identification card, such as a credit card, a bank card, a cash payment card, an authorization card, an identity card or a passport personalisation page.
[0017] The security elements described can be present as a separate security element applied to a data carrier to be secured, but they can also be part of the data carrier to be secured itself.
[0018] The invention further includes a method for producing an optical security element of the type described, in which at least two effect regions for producing different optical effects are produced on a carrier, which effect regions adjoin one another along a boundary line, wherein at least one of the two effect regions is formed by a micromirror region with directionally reflecting micromirrors, and the boundary line of the two said effect regions is formed with non-smooth edges, whereby a transition region is formed in the two effect regions along the boundary line, in which transition region the optical effect of the first effect region merges smoothly into the optical effect of the second effect region when viewed.
[0019] Further embodiments and advantages of the invention are explained below with reference to the figures, in which a true-to-scale and true-to-proportion reproduction has been omitted in order to increase clarity.
[0020] They show:
[0021] Fig. 1 shows a schematic representation of a banknote with a security element according to the invention with two effect areas bordering each other along a boundary line,
[0022] Fig. 2 in (a) a detailed view of a security element according to the invention with a transition region with perfect alignment of the two effect regions, and in (b) a security element not according to the invention without a transition region,
[0023] Fig. 3 in (a) a detailed view of a security element according to the invention with a typical positional deviation of the effect areas and in (b) a non-inventive security element without a transition area, Fig. 4 in a security element according to the invention the transition area between the effect areas with a non-smooth-edged boundary line,
[0024] Fig. 5 in (a) and (b) the transition region of two further security elements according to the invention, and
[0025] Fig. 6 illustrates a security element in which the first effect region is formed by a metallized micromirror region and the second effect region by a demetallized micromirror region, wherein (a) the design is given, (b) as a comparative example shows a security element not according to the invention without a transition region and (c) a security element according to the invention with a transition region.
[0026] The invention will now be explained using the example of security elements for banknotes. Figure 1 shows a schematic representation of a banknote 10 with a security element 12 according to the invention.
[0027] The security element 12 contains two effect regions 14, 16 for generating different optical effects, which border one another along a boundary line 18. In the exemplary embodiment, the effect region 14 is formed by a micromirror region with directionally reflecting micromirrors, while the effect region 16 represents a hologram.
[0028] As a special feature, a transition area 20 is formed along the boundary line 18 between the two effect areas 14, 16, in which, upon observation, the optical effect of the first effect area 14 smoothly transitions into the optical effect of the second effect area 16. The two different effect areas 14, 16 typically exhibit certain register fluctuations compared to (structural) features created in other production steps, which, however, are concealed by the transition area. As described above, conventional designs often have the problem that register fluctuations reveal weaknesses in production processes and that the visible positional deviations of the effect areas are irritating to the observer.
[0029] These difficulties are overcome by providing a smooth, soft transition between the two effect areas 14, 16, as explained in more detail in Figures 2 to 5.
[0030] First, Fig. 2(a) shows a detailed view of the security element 12 with the effect regions 14, 16 and the transition region 20 formed along the boundary line 18, assuming an idealized perfect alignment of the two effect regions 14, 16, in the present case an alignment in which, in the exemplary embodiment, the boundary line 18 between the effect regions lies exactly at the height of the structural feature 22 in accordance with the design specification. For comparison, Figure 2(b) shows a security element 12' not according to the invention without a transition region with such an idealized, perfect alignment of the boundary line 18' with respect to the structural feature 22.
[0031] Figure 3(a) shows the security element 12 with a typical positional deviation A of the effect regions 14, 16 relative to the structural feature 22, which occurs in a real security element due to the unavoidable register fluctuations during the generation of the structural feature 22 in a separate operation. Figure 3(b) shows, for comparison, a non-inventive security element 12' without a transition region with the same positional deviation A as the security element 12.
[0032] Due to the design of the transition region 20 described in more detail below, the optical effect of the first effect region 14 transitions seamlessly into the optical effect of the second effect region 16. The inventive designs of Figs. 2(a) and 3(a) therefore have no sharp boundary between the two optical effects, so that there is no fixed visual reference point for the correct position of the structural feature 22. The differences between the idealized, perfectly aligned position of Fig. 2(a) and the position typically occurring in reality according to Fig. 3(a) are therefore only slight and are not distracting upon observation.
[0033] In contrast, the misalignment of the sharp boundary line 18' with the structural feature 22 in the comparison security element 12' of Fig. 3(b) is clearly perceptible due to the clearly recognizable position of the boundary line 18' and leads to the above-mentioned adverse effects.
[0034] With reference to Fig. 4, the transition region 20 between the two effect regions 14, 16 is created by the boundary line 18 of the two effect regions being formed with non-smooth edges on a length scale not visible to the naked eye along the boundary line. In the exemplary embodiment in Fig. 4, the boundary line 18 is sawn and has a sawtooth structure with a plurality of fine, pointed prongs 32 whose width is less than 100 pm and thus below the resolution limit of the human eye. The height H of the prongs 32 essentially corresponds to the width of the desired transition region 20 and can be, for example, 0.5 mm or even a few millimeters.
[0035] Due to the jagged design of the boundary line 18, the surface area of the first effect region 14 continuously decreases from 100% to 0% across the height H of the prongs 32 in a direction 30 perpendicular to the boundary line 18, while simultaneously the surface area of the second effect region 16 continuously increases from 0% to 100%. The two effect regions 14, 16 thus merge along the boundary line 18.
[0036] The sawtooth structure of the boundary line 18 can advantageously be regular, i.e. have equally sized teeth at equal intervals, but it can also be irregularly formed, as shown in the embodiment of Fig. 4.
[0037] Figure 5 shows two further embodiments of security elements according to the invention. In the design of Fig. 5(a), the boundary line 18 between the effect regions 14, 16 is formed with projections / incisions 34 that are rounded in both directions. As explained above, such a shape of the boundary line 18 is referred to as lobed, indented, or corrugated, depending on the extent of the extension of the projections or incisions into the adjacent effect region.
[0038] The boundary line 18 of Fig. 5(b) has a mixed shape, in which the projections / incisions 36 taper towards the effect area 14, but are rounded towards the effect area 16. Such a design is referred to as notched (pointed incisions, round projections) when viewed from the direction of the effect area 14, and as toothed (round incisions, pointed projections) when viewed from the direction of the effect area 16.
[0039] Irregular arrangements of the projections and incisions 34, 36 are also shown in Fig. 5, but it is understood that the projections and incisions can also be arranged regularly with the same shape and the same distance along the boundary line.
[0040] Also in the designs of Fig. 5, in the transition region 20 the area share of the first effect region 14 decreases continuously from 100% to 0% over the height of the projections or incisions 34, 36, while at the same time the area share of the second effect region 16 increases continuously from 0% to 100%, so that the optical effect of the first effect region 14 in the transition region 20 merges smoothly into the optical effect of the second effect region 16.
[0041] Figure 6 shows a security element according to a further embodiment of the invention, in which the first effect region is formed by a metallized micromirror region 54 and the second effect region by a demetalized micromirror region 56. The two effect regions 54, 56 also exhibit different micromirror effects.
[0042] For clarification, Fig. 6(a) shows the design specification of an idealized, star-shaped demetallization 46 within a surrounding metallized region 44. Figure 6(b) shows, as a comparative example, a security element 52' not according to the invention without a transition region, i.e., with a sharp boundary 58' and with a certain register fluctuation of the demetallization 56' within the metallized region 54'. As can be seen in Fig. 6(b), the occurrence of the register fluctuations is clearly perceptible to an observer due to the irregular star shape and the sharply defined boundary 58'.
[0043] Figure 6(c) finally shows a security element 52 according to the invention, in which the boundary line between the demetallized micromirror region 56 and the metallized micromirror region 54 is formed with non-smooth edges on a length scale that cannot be resolved with the naked eye along the boundary line of the two micromirror regions.
[0044] For example, the boundary line can have a sawtooth structure with a multitude of fine, pointed teeth, as shown in Fig. 4. As a result, the density of the metallization decreases continuously from 100% to 0% in a direction perpendicular to the local orientation of the boundary line in a transition region 60 from the outside, i.e., the fully metallized effect region 54, to the inside, i.e., the fully demetallized effect region 56. Of course, the boundary line can also be notched, toothed, lobed, indented, or wavy.
[0045] In this way, a soft, flowing transition is achieved between the metallized region 54 and the demetallized region 56, which conceals the presence of register fluctuations, as illustrated in Fig. 6(c).
[0046] List of reference symbols
[0047] 10 banknotes
[0048] 12 Security element
[0049] 12' Comparison example
[0050] 14, 16 effect areas
[0051] 18 boundary line
[0052] 18' boundary line in comparison example
[0053] 20 Transition area
[0054] 22 Structural feature
[0055] 30 Direction perpendicular to the boundary line
[0056] 32 pointed points
[0057] 34, 36 projections
[0058] 44 metallized areas in design specification
[0059] 46 Demetallization in design specification
[0060] 52 security element
[0061] 52' Comparison example
[0062] 54 metallized micromirror area
[0063] 54' metallized area in the comparison example
[0064] 56 demetallized micro mirror area
[0065] 56' Demetallization in comparison example
[0066] 58' sharply defined boundary in the comparison example
[0067] 60 transition area
Claims
Patent claims 1. Optical security element for securing valuables, with at least two effect regions for generating different optical effects, wherein the effect regions border one another along a boundary line, and at least one of the two effect regions is formed by a micromirror region with directionally reflecting micromirrors, characterized in that the boundary line of the two said effect regions is not designed with smooth edges, whereby a transition region is formed in the two effect regions along the boundary line, in which transition region the optical effect of the first effect region merges smoothly into the optical effect of the second effect region when viewed.
2. Optical security element according to claim 1, characterized in that the at least two effect regions are formed by micromirror regions with directionally reflecting micromirrors and different micromirror effects.
3. Optical security element according to claim 2, characterized in that one of the micromirror regions is metallized and another of the micromirror regions is not metallized, in particular demetallized.
4. Optical security element according to claim 1, characterized in that one of the effect regions is formed by a micromirror region with directionally reflecting micromirrors and another of the effect regions is formed by a diffractive relief structure, in particular a hologram, a holographic grating image or a hologram-like diffraction structure.
5. Optical security element according to at least one of claims 2 to 4, characterized in that the micromirror region(s) each contain non-diffractive mirrors and preferably plane mirrors, concave mirrors and / or Fresnel-type mirrors.
6. Optical security element according to at least one of claims 1 to 5, characterized in that the non-smooth-edged boundary line is sawn, notched, toothed, lobed, indented or corrugated.
7. Optical security element according to at least one of claims 1 to 6, characterized in that the effect regions merge into one another along the boundary line.
8. Optical security element according to at least one of claims 1 to 7, characterized in that one of the effect regions forms an outer effect region which surrounds another of the effect regions which forms an inner effect region, and the boundary line is formed by the outline of the inner effect region.
9. Optical security element according to at least one of claims 1 to 8, characterized in that the boundary line of the two effect regions is non-smooth-edged on a length scale below the resolution limit of the human eye.
10. Optical security element according to at least one of claims 1 to 9, characterized in that the non-smooth-edged boundary line has a plurality of projections with sharp changes in direction on a length scale below the resolution limit of the human eye.
11. Optical security element according to claim 10, characterized in that the projections have widths and spacings below the resolution limit of the human eye, preferably below 150 gm, in particular below 100 gm.
12. Optical security element according to claim 10 or 11, characterized in that the projections are arranged uniformly, in particular periodically, along the boundary line, the period length being below 300 μm, preferably below 200 μm, particularly preferably between 10 and 100 μm, or that the projections are not arranged uniformly along the boundary line, preferably with a varying spacing whose mean value is below 300 μm, preferably below 200 μm, particularly preferably between 10 and 100 μm.
13. Optical security element according to at least one of claims 1 to 12, characterized in that the height of the projections is between 50 μm and 50 mm, preferably between 50 μm and 10 mm, particularly preferably above the resolution limit of the human eye and in particular between 0.5 mm and 5 mm.
14. Optical security element according to at least one of claims 1 to 13, characterized in that the width of the transition region is between 50 mm and 10 mm, preferably above the resolution limit of the human eye and in particular between 0.5 mm and 5 mm.
15. A data carrier with an optical security element according to one of claims 1 to 14.
16. A method for producing an optical security element according to one of claims 1 to 14, in which at least two effect regions for generating different optical effects are generated on a carrier, which effect regions adjoin one another along a boundary line, at least one of the two effect regions being formed by a micromirror region with directionally reflecting micromirrors, and the boundary line of the two said effect regions being formed with non-smooth edges, as a result of which a transition region is formed in the two effect regions along the boundary line, in which transition region the optical effect of the first effect region merges smoothly into the optical effect of the second effect region when viewed.