EP3291997B1 - Optically variable security element - Google Patents

Description

The invention relates to an optically variable security element for protecting objects of value, a method for producing such a security element and a correspondingly equipped data carrier.

Data carriers, such as value or identity documents, or other objects of value, such as branded items, are often provided with security elements for protection that allow the authenticity of the data carrier to be checked and at the same time serve as protection against unauthorized reproduction. Security elements with viewing angle-dependent effects play a special role in securing authenticity, since these cannot be reproduced even with the most modern copiers. The security elements are equipped with optically variable elements which give the viewer a different image impression from different viewing angles and, for example, show a different color or brightness impression and / or a different graphic motif depending on the viewing angle.

In this context, optically variable security elements are known which, when the security element is tilted, show various movement or tilting effects, such as moving bars, moving pictorial representations, pumping effects or three-dimensional representations. To implement the optically variable appearances, different techniques are used in the prior art, with which some of these movement effects can typically be implemented particularly well and others less well.

For example, with moiré magnification arrangements based on microfocusing elements and microimages, especially moving periodic Motifs are well represented. On the other hand, tilt images or representations with an excellent center position, i.e. a view that always looks the same for all security elements produced at the same viewing angle, are often difficult to realize because of the high-precision registration of the microfocusing elements and microimages required.

Holograms can basically show any animation through nested representations that are visible at different tilt angles, but the quality and luminosity of the representations are heavily dependent on good lighting. The same applies to security elements with micromirror arrangements if the different views of an animation are to be nested in one another there, even if micromirror arrangements are generally more luminous than holograms.

From the pamphlet WO 2011/051669 A1 For example, a safety device is known which includes at least two lenticular devices, each lenticular device having an array of elongated lenticular focusing elements each disposed over a set of image strips. The longitudinal directions in which the lens-shaped focusing elements of the two lenticular devices extend are different.

The pamphlet EP 1 710 756 A1 describes a printed image which is in the form of an array of magnetically aligned platelets or flakes of uniform shape and size, the magnetic platelets being arranged to produce optically illusory images that can serve as security devices.

In the case of optically variable security features based on printing inks with magnetically aligned reflective pigments, the effects generated are very bright, but to achieve a certain movement effect, appropriate magnets are always required to align the pigments, which in practice severely limits the variety of effects and resolution.

The optically variable effects mentioned are often difficult to individualize, that is to say, for example, they can be adapted to a specific currency or a specific value. A widespread possibility of individualization is demetallization in certain areas, in which an effect layer is left out in some areas, for example in the form of a number. Such negative texts are, however, comparatively inconspicuous, which increases the risk that a forger will, for example, misuse a genuine security element of a lower denomination banknote is used to counterfeit a higher denomination banknote without the untrained or casual observer noticing.

Proceeding from this, the invention is based on the object of specifying a security element of the type mentioned at the outset which exhibits a novel, optically variable effect that clearly stands out from conventional effects. Ideally, the optically variable effect also enables a conspicuous and easily memorable individualization of the security element or of the data carrier provided with it.

This object is achieved by the features of the independent claims. Developments of the invention are the subject of the dependent claims.

According to the invention, a generic security element shows, depending on the viewing angle, a motif with at least one curve representation, which is visible from a first viewing direction as an output curve with two or more contiguous, non-collinear segments, and which breaks down into the individual segments when the security element is tilted about a predetermined axis, in that the segments of the exit curve move alternately in different directions away from the exit curve.

According to the invention, the security element has a planar motif area with a plurality of optically effective elements which each direct incident light in a preferred direction, the segments of the output curve in the planar motif area being assigned a movement segment in the form of a sub-area of the planar motif area, in which the optically effective elements are arranged and aligned in such a way that they show the starting curve with the connected segments from the first viewing direction, and that they show curve representations from the viewing directions tilted about the predetermined axis in which the segments alternate in different directions and with increasing Tilt angle are increasingly further away from the starting curve.

The connected segments of the output curve are not collinear, that is, they do not all lie on a straight line. At least two of the connected segments of the starting curve are not on a straight line. This also does not rule out that segments spaced apart from one another are parallel to one another, such as the two cover lines of the letter "Z" connected by the diagonal.

At least one curve representation of the motif preferably breaks down into three or more, preferably four or more, or even six or more segments when the security element is tilted. Since the segments move alternately in different directions away from the starting curve when the security element is tilted, the moving segments are no longer contiguous but are initially still adjacent, so that the visual impression of a curve breaking up into the individual segments is created.

The output curve of at least one curve display advantageously shows an alphanumeric character, a symbol, such as the euro symbol or another currency symbol, or another information-carrying character. In particular, two or more output curves can also be provided which together form a number, such as a banknote's value number, a sequence of letters or a sequence of symbols.

The movement segments of the curve representations advantageously have a width that is between 10% and 100%, preferably between 20% and 50% of the extent of the initial curve of the curve representation. The extension of the movement segments perpendicular to the associated segment of the starting curve is referred to as the width of the movement segments. Within a curve display, the movement segments advantageously all have the same width.

The optically effective elements each direct incident light in a preferred direction, the mechanism of light deflection depending on the type of optically effective elements. For example, the optically effective elements can be reflective facets that form small micromirrors that direct incident light in a preferred direction given by the condition “angle of incidence equals angle of reflection”. In addition to reflection, light refraction, for example by lens elements or prism elements, or light diffraction, for example by hologram grating areas, can also be considered. The light deflection by the optically effective elements can take place in reflection, in transmission or both in reflection and in transmission.

In an advantageous variant of the invention, the optically effective elements are formed by radiation-optically acting facets, the orientation of which is characterized by an angle of inclination α relative to the plane of the flat motif area and an azimuth angle θ in the plane of the flat motif area. The dimensions of the facets are preferably so large that no or hardly any diffraction effects occur, so that the facets essentially only have a radiation-optical effect. In particular, the facets advantageously have a smallest dimension of more than 2 µm, preferably of more than 5 μm, in particular of more than 10 μm. In particular for use in bank notes and other documents of value, the facets preferably have a height of less than 100 μm, preferably less than 50 μm, in particular less than 10 μm. The facets can be arranged regularly, for example in the form of a 1- or 2-dimensional periodic grid, for example a sawtooth grid, or else aperiodically.

The optically active elements can also advantageously be formed by diffraction-optically acting grating fields with a grating pattern made up of parallel grating lines. The preferred direction of the light deflection is given by the grating parameters of the grating pattern, in particular by the grating period p and the azimuth angle ϕ, which specifies the angle that the grating lines of the grating pattern enclose with a reference direction.

In a further advantageous variant of the invention, the optically effective elements are formed by channel-shaped and / or rib-shaped structural elements lying next to one another and extending along a longitudinal direction, as they are, for example, in the publication WO 2014/117938 A1 are described in more detail, the disclosure content of which is included in the present application.

The flat motif area can be designed to be reflective, so that the output curve and the breakdown of the output curve into individual segments are visible in reflection.

In advantageous configurations, the optically effective elements are formed by reflection elements that are molded into an embossing lacquer and with a reflection-increasing coating are provided. The reflection-increasing coating can be formed by a metallization and / or can have a color shift effect, in which case the coating advantageously consists of a thin film interference layer system with reflector, dielectric spacer layer and absorber.

The flat motif area can also be at least partially transmitting, so that the output curve and the breakdown of the output curve into individual segments are visible in transmission. The flat motif area can also be designed to be partially reflective as well as partially transmissive, so that the output curve and the breakdown of the output curve into individual segments are visible both in reflection and in transmission.

In advantageous designs, the optically effective elements are formed by transmission elements in the form of transparent or semitransparent diffraction structures, transparent or semitransparent prismatic structures or transparent or semitransparent micro-relief structures. As already mentioned above, the transmission elements can at the same time have reflective properties and thus generate an additional movement effect in reflection.

In an advantageous development of the invention it is provided that the motif of the security element contains at least one second curve representation, which is visible from a second viewing direction as a second output curve with two or more contiguous, non-collinear segments, and which is visible when the security element is tilted around the predetermined axis is broken down into the individual segments in that the segments of the second output curve alternate in different directions move away from the second output curve, the segments of the second output curve in the planar motif area each being assigned a second movement segment in the form of a sub-area of the planar motif area in which the optically effective elements are arranged and aligned so that they are the show second output curve with the connected segments, and that they show curve representations from viewing directions tilted about the predetermined axis, in which the segments are located alternately in different directions and increasingly further away from the second output curve as the tilt angle increases.

In an advantageous variant of the invention, the movement segments of the first and second curve display do not overlap.

In order to achieve a large visual separation of the two curve representations when viewing, the first and second viewing directions advantageously enclose an angle of at least 5 °, preferably at least 10 ° and particularly preferably at least 20 °.

In an advantageous variant of the invention, at least one segment of the first curve display is also a segment of the second curve display, so that when the security element is tilted, the second curve display is composed at least partially of segments of the disintegrated first curve display.

It goes without saying that the motif of the security element can in the same way also contain more than two curve representations, which are visible from different viewing directions as coherent output curves.

The security element advantageously represents a security thread, a tear-open thread, a security tape, a security strip, a patch or a label for application to a security paper, document of value or the like.

The invention also contains a data carrier with a security element of the type described, wherein the security element can be arranged both in an opaque area of the data carrier and in or above a transparent window area or a continuous opening of the data carrier. The data carrier can in particular be a value document, such as a bank note, in particular a paper bank note, a polymer bank note or a film composite bank note, a share, a bond, a certificate, a voucher, a check, a high-quality admission ticket, but also an identity card such as a credit card, a bank card, a cash card, an authorization card, an identity card or a passport personalization page.

• eine gewünschte Ausgangskurve mit zwei oder mehr zusammenhängenden, nicht kollinearen Segmenten festgelegt wird,
• für die Segmente der Ausgangskurve jeweils Bewegungssegmente festgelegt werden, in denen sich die Segmente der Ausgangskurve beim Kippen des Sicherheitselements bewegen, und
• in einem flächigen Motivbereich in den festgelegten Bewegungssegmenten optisch wirksame Elemente so angeordnet und ausgerichtet werden, dass sie aus der ersten Betrachtungsrichtung die Ausgangskurve mit den zusammenhängenden Segmenten zeigen, und dass sie aus um die vorbestimmte Achse gekippten Betrachtungsrichtungen Kurvendarstellungen zeigen, in denen die Segmente abwechselnd in unterschiedliche Richtungen und mit zunehmendem Kippwinkel zunehmend weiter von der Ausgangskurve entfernt liegen.

The invention further includes a method for producing an optically variable security element of the type described above, in which

• a desired output curve with two or more connected, non-collinear segments is determined,
• Movement segments in which the segments of the output curve move when the safety element is tilted are defined for the segments of the exit curve, and
• optically effective elements are arranged and aligned in a flat motif area in the defined movement segments in such a way that they show the starting curve with the connected segments from the first viewing direction, and that they show curve representations from viewing directions tilted about the predetermined axis in which the segments alternate in different directions and with increasing tilt angle are increasingly further away from the starting curve.

Further exemplary embodiments as well as advantages of the invention are explained below with reference to the figures, in the representation of which a reproduction true to scale and proportion was dispensed with in order to increase the clarity.

Fig. 1

eine schematische Darstellung einer Banknote mit einem erfindungsgemäßen optisch variablen Sicherheitselement,

Fig. 2

in (a) bis (e) das Erscheinungsbild des optisch variablen Sicherheitselements der Fig. 1 bei verschiedenen Kippwinkeln zwischen -20° und +20°,

Fig. 3

die Kurvendarstellungen der Ziffern "5" und "0" der Wertzahl "50" der Fig. 1 mit zur Illustration voneinander abgesetzten Segmenten,

Fig. 4

eine schematische Aufsicht auf einen flächigen Motivbereich, der als Ausschnitt des Sicherheitselements der Fig. 1 eine Darstellung der Wertzahl "50" zeigt,

Fig. 5

schematisch zwei der Bewegungssegmente der Ziffer "5" der Fig. 4 im Detail,

Fig. 6 und 7

jeweils einen schematischen Querschnitt durch den flächigen Motivbereich der Figuren 4 bzw. 5 entlang der Linien VI-VI bzw. VII-VII,

Fig. 8

die Werte des Orientierungsparameters k für das Ausführungsbeispiel der zerfallenden Wertzahl "50" in einer Graustufendarstellung,

Fig. 9

in (a) bis (i) das visuelle Erscheinungsbild eines Sicherheitselements nach einem weiteren Ausführungsbeispiel der Erfindung bei verschiedenen Kippwinkeln, und

Fig. 10

die Werte des Orientierungsparameters k für das Ausführungsbeispiel der Fig. 9 in Graustufendarstellung.

Show it:

Fig. 1

a schematic representation of a bank note with an optically variable security element according to the invention,

Fig. 2

in (a) to (e) the appearance of the optically variable security element of Fig. 1 at different tilt angles between -20 ° and + 20 °,

Fig. 3

the graphs of the digits "5" and "0" of the value number "50" of the Fig. 1 with segments separated from one another for illustration purposes,

Fig. 4

a schematic plan view of a flat motif area, which is used as a section of the security element of Fig. 1 shows a representation of the value number "50",

Fig. 5

schematically two of the movement segments of the number "5" of the Fig. 4 in detail,

Figures 6 and 7

each a schematic cross section through the planar motif area of Figures 4 or 5 along the lines VI-VI or VII-VII,

Fig. 8

the values of the orientation parameter k for the exemplary embodiment of the decaying value number "50" in a gray scale representation,

Fig. 9

in (a) to (i) the visual appearance of a security element according to a further exemplary embodiment of the invention at different tilt angles, and

Fig. 10

the values of the orientation parameter k for the embodiment of FIG Fig. 9 in grayscale display.

The invention will now be explained using the example of security elements for bank notes. Figure 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 wide security strip applied to the banknote substrate. It goes without saying that the invention is not limited to security strips and bank notes, but can be used with all types of security elements, for example with labels on goods and Packaging or for securing documents, ID cards, passports, credit cards, health cards and the like. In the case of bank notes and similar documents, security threads or transfer elements can also be used, for example, in addition to security strips.

The security strip 12 has a metallic appearance and, when viewed vertically, shows the number "50" spaced several times one above the other. Each representation of the value number “50” consists of two curve representations 14A, 14B, which are each formed from contiguous lines “5” and “0”, respectively. The curve representations 14A, 14B can be seen in a vertical plan view as light lines in front of the somewhat darker, but likewise shiny metallic background of the security strip 12. This visual impression when viewed vertically is in Fig. 2 (c) shown again in more detail.

When the banknote 10 is tilted 16A, 16B about its longitudinal axis, the security strip 12 shows an astonishing optical effect: The originally contiguous curve representations 14A, 14B, hereinafter also often referred to as output curves, disintegrate for the viewer into a plurality of individual segments 18, which become more and more common Move the tilt alternately in different directions away from the respective starting curve.

For illustration purposes, the Figures 2 (a) and (b) the appearance of the security element 12 with a tilt of 20 ° or 10 ° downwards (tilting direction 16A), while the Figures 2 (d) and (e) show the visual appearance with a tilt of 20 ° or 10 ° upwards (tilting direction 16B). Overall shows Fig. 2 for example five tilt positions with different visual impressions. In practice included according to the invention Security elements often significantly more, for example 6 to 20 tilt positions with different visual impressions.

Based on the interrelated representation of the output curves 14A, 14B in FIG Fig. 2 (c) When tilting the bank note 10, a viewer can see a more or less continuously appearing "disintegration" of the output curves "5" and 0 "into individual line segments, in which the initially connected segments separate from one another and then increasingly move away from one another until a substantially a disordered appearance arises in which the original output curves are no longer or can hardly be recognized ( Figures 2 (a) or 2 (e) ). When tilting back, the output curves 14A, 14B from the individual segments are reassembled into the value number "50", only to then break down into individual segments when tilting further in the other tilting direction.

The creation of this amazing decay effect is now based on the Figures 3 to 7 explained in more detail, whereby Fig. 3 shows the curve representations 14A, 14B of the value number "50" with segments 18 somewhat separated from one another for illustration purposes, Fig. 4 is a schematic plan view of a planar motif area 20, which is a section of the security element 12 of FIG Fig. 1 forms, Fig. 5 two of the motion segments of Fig. 4 represents in detail and the Figures 6 and 7 each a cross-section through the flat motif area of Figures 4 and 5 along the lines VI-VI and VII-VII of the Fig. 5 demonstrate.

As in the graphs 14A, 14B of Fig. 3 Clearly visible, each of the two output curves in the form of the digits “5” and “0” consists of several connected, non-collinear segments 18. Each of these segments 18 is a sub-area within the flat motif area 20 22, in which the segment 18 appears to move when the security element 12 is tilted and which is therefore referred to below as the movement segment 22.

The movement segments 22 extend perpendicularly from the output curve essentially equally on both sides, the width of the segments advantageously being between 20% and 50% of the extension of the output curve. Figure 4 In addition to these movement segments 22, FIG. 12 also shows the output curves 14A and 14B, the connected segments of which lie in the center of the movement segments 22 in the exemplary embodiment.

As in the detail of the Fig. 5 and the cross sections of the Figures 6 and 7 As shown, the planar motif area 20 contains a plurality of optically effective elements in the form of reflective facets 30, which in the exemplary embodiment have a base area of 15 μm × 15 μm and a maximum height of approximately 5 μm. As best in the Figures 6 and 7 As can be seen, the facets 30 are inclined at different angles in the y-direction, ie along the tilting directions 16A, 16B, and reflect incident light in a preferred direction which is given for each facet 30 by the condition "angle of incidence equals angle of reflection".

The facets 32 respectively arranged in the middle of the movement segments 22A and 22B have an angle of inclination α = 0 ° with respect to the plane of the flat motif region 20 and therefore reflect essentially vertically upwards when the incident light is perpendicular. The facets 34 offset in the + y direction by the facets 32 in the movement segment 22A have increasing angles of inclination α up to an angle of inclination α = + 20 ° at the upper edge 24-O of the movement segment, while those in the -y direction offset facets 36 have decreasing angles of inclination α up to an angle of inclination α = -20 ° at the lower edge 24-U of the movement segment.

In the immediately adjacent movement segment 22B, the angles of inclination of the facets change in the opposite way, that is, starting from the facets arranged in the center with a tilt angle α = 0 °, the facets 36 offset in the + y direction have decreasing angles of inclination α up to an angle of inclination α = -20 ° at the upper edge 26-O of the movement segment 22B, while the facets 34 offset in the -y direction have increasing angles of inclination α up to an angle of inclination α = + 20 ° at the lower edge 26-U of the movement segment 22B exhibit.

If the security element 12 with the surface area 20 is now tilted downwards by a few degrees (tilting direction 16A), starting from a vertical view, the reflection condition "angle of incidence equals angle of reflection" in movement segment 22A for facets 34 and offset upwards (in + y direction) in the movement segment 22B for facets 34 offset downwards (in the -y direction). The reverse is true for tilting a few degrees upwards in the tilting direction 16B. The segments 18 of the curve representation 14A visible in the movement segments 22A, 22B therefore run away from the initial curves in the opposite direction for the viewer when tilted and move away from one another.

The occupation with optically variable elements described by way of example for the movement segments 22A, 22B is correspondingly also carried out for the other movement segments 22 of the surface region 20, so that the angles of inclination of the facets 30 in adjoining movement segments change in opposite ways. In this way the segments 18 of the exit curves 14A, 14B run alternately in different directions for the viewer along the exit curves, so that the exit curves appear to disintegrate when the security element is tilted.

In the embodiment of Figures 4 to 7 the visual divergence of the segments 18 is realized, for example, by inclination angles of reflecting facets 30 increasing in different directions. Since other optically effective elements can also be used instead of reflective facets, the divergence of the curve segments is advantageously generally described by an orientation parameter k which, by definition, lies between -1 and +1. The position of the connected segments in the output curve typically corresponds to the value k = 0, while the extreme values k = ± 1 are assumed for each segment 18 at the opposite edges of the movement segment 22. By using a general orientation parameter k , the shape of the movement segments and the movement behavior of the segments when tilted can be described independently of the actual implementation of the optically effective elements.

For illustration shows Fig. 8 the values of the orientation parameter k for the exemplary embodiment of the decaying value number “50” in a gray level representation 40 in which the gray value white corresponds to the value k = + 1 and the gray value black corresponds to the value k = -1. As in Fig. 8 the individual segments 18 of the curve representations 14A, 14B can be seen at k = 0, represented by a medium gray, contiguous and form the digits “5” or “0”. With other k values, for example with k = -1 (black), the segments are separated from one another and show a representation of the disintegrated output curve.

In the exemplary embodiment, the orientation parameter k runs alternately either from -1 to +1 or from +1 to -1 within each of the movement segments 22. For example, the orientation parameter in the movement segment 22A runs from the lower to the upper edge from -1 to +1, while in the adjacent movement segment 22B it runs from +1 to -1 from the lower to the upper edge. As in Fig. 8 shown this alternating course continues along the entire curve display.

aus dem Orientierungsparameter k erhalten. Variiert k zwischen -1 und +1, so ändert sich der Neigungswinkel α entsprechend zwischen -20° (Neigung nach unten) und +20° (Neigung nach oben).When converting the optically effective elements through the facets 30, the angle of inclination of the facets in the y direction was given by the relationship $$\alpha \left(k\right)=k\cdot \mathrm{20th}°,-1\le k\le 1$$

obtained from the orientation parameter k . If k varies between -1 and +1, the inclination angle α changes accordingly between -20 ° (inclination downwards) and + 20 ° (inclination upwards).

With a two-dimensional specification of the orientation parameter k as in Fig. 8 and a relationship between the orientation parameter k and the angles of inclination of the facets 30, such as, for example, relationship (F1), the facets of a planar motif area can be clearly described for a given size of the facets. A corresponding reflective surface area 20 can then be produced in a manner known per se, for example, by embossing the facets described in this way in an embossing lacquer layer and then metallizing.

der Größe der Bewegungssegmente.Returning to the representation of the Fig. 2 show the views of the Fig. 2 expressed by the orientation parameter k from (a) to (e) der Sequentially the appearance at k = -1, k = -0.5, k = 0 (output curves), k = + 0.5 and k = + 1. When implementing a k value specification using reflective facets, it must also be taken into account that in practice the facets do not reflect in any sharp angular range, but rather reflect in an angular range of a few degrees depending on the design and the ambient light conditions. If the facets 30 light up, for example, in an angular range of 5 °, this angular range, together with the angular spread of the movement range, defines a line width under which the initial curve and the disintegrating segments appear. With the specified values, for example, a line width of $$\mathrm{s}=5°/\left(2\times \mathrm{20th}°\right)=1/\mathrm{8th}$$

the size of the motion segments.

The k values for a desired motif can be specified using suitable mathematical algorithms; the k value can, for example, increase proportionally to the distance between the segments and the starting curve. Alternatively, the values can also be generated manually by a designer, for example as a color gradient in a design sheet. The value of the orientation parameter preferably increases proportionally to the distance of a segment from the starting curve to the edge of the movement area to +1 or decreases to -1, as in the exemplary embodiment in FIG Fig. 8 shown.

In principle, the relationship between the orientation parameter and the distance to the starting curve can of course also be non-linear. As a result, the line thickness or the dynamics of movement can be varied depending on the tilt angle. For example, the k values can vary very widely around the k value of the output curve, so that a sharp representation of the output curve is achieved. To the edge The k value can then vary more slowly towards the movement segments, which increases the line width and increases the dynamics.

In some configurations it can also be provided that the k value does not run through the entire range between -1 and +1 in all segments. If the k value in a segment only runs up to a k value of +0.5, for example, the segment appears to disappear when tilted into viewing angles that correspond to k values above 0.5, since then none are optically effective Elements are present that direct incident light towards the viewer at these viewing angles.

With the relationship (F1) given above between the angles of inclination of reflective facets and the orientation parameter k , the facets can of course also be selected steeper or flatter or alternatively or additionally inclined in the x direction instead of in the y direction. It is only essential that when tilting around a given tilt axis, the optically effective elements with k = -1 to k = + 1 become visible in sequence, for example light, dark or colored, and then invisible again, so that a corresponding movement effect for the segments results.

für Azimutwinkel zwischen +30° und -30° oder $$p\left(k\right)=1000\mathrm{nm}+k\cdot 500\mathrm{nm},-1\le k\le 1$$

für Gitterperioden zwischen 500 nm und 1,5 µm.If small hologram grating areas are used as optically effective elements, the orientation parameter k can be linked, for example, to the azimuth angle ϕ and / or the grating period p of the hologram grating areas, for example in the form $$\phi \left(k\right)=k\cdot \mathrm{30th}°,-1\le k\le 1$$

for azimuth angles between + 30 ° and -30 ° or $$p\left(k\right)=1000\mathrm{nm}+k\cdot 500\mathrm{nm},-1\le k\le 1$$

for grating periods between 500 nm and 1.5 µm.

In further designs, microrelief structures with channel-shaped and / or rib-shaped structural elements can also be used as optically effective elements, as they are for example in the publication WO 2014/117938 A1 are described, the disclosure content of which is included in the present application. In this case, the orientation parameter k can be linked to the azimuth angle of the structural elements, for example.

It goes without saying that in addition to reflective facets, hologram gratings and micro-relief structures, other optically effective elements can also be used. In the context of the invention, it is only important that the described moving segments are shown to a viewer when tilting, regardless of whether they are light, dark, colored or visible in some other way, and whether this is done from above or through.

Thus, according to a further design option, micro-lens or micro-concave mirror grids can also be used as optically effective elements which, together with line patterns, produce moiré magnification effects. For this purpose, the line patterns have approximately the same period as the microlens or micro-concave mirror rasters and are arranged approximately in the focal plane of the microlenses or micro-concave mirror. The microlenses or micro concave mirrors direct incident light in a direction depending on the viewing angle onto or next to the lines, so that they appear to a viewer either in the color of the lines or in the color of the spaces. In this case, the orientation parameter k indicates how far the line pattern is locally shifted with respect to the grid of the microlenses or micro-concave mirrors. For example, with a k value of -1, the center point of the lines of the grid can be on a first edge of the individual microlenses or micro-concave mirrors and with a k value of +1 on a second edge of the microlenses or micro-concave mirrors opposite the first edge .

Both with facets and with hologram gratings and microrelief structures, the described movement effects can be generated not only when viewed from above, but also for viewing when viewed through. If, for example, the facets are not embedded in a material with the same or very similar refractive index, they act like small prisms when viewed through, so that differences in brightness result in the transmitted light and a movement effect according to the invention can be generated in transmitted light.

In particular, with a thin, semitransparent coating, for example a thin metal layer, it can be achieved that the same embossed structures as reflective facets produce a movement effect according to the invention in plan view and at the same time with the effect of microprisms additionally a movement effect according to the invention in transparency. In a similar way, the above-mentioned microrelief structures and hologram grids can also be coated, for example, semitransparently, for example with a very thin metal layer, or with a highly refractive, transparent coating for viewing in transparency.

The concept described is used with particular advantage in so-called RollingStar® security threads or LEAD strips with micromirrors, in other words, for designs with facets or micromirrors that are embossed with embossing heights of a maximum of 5 µm in an embossing lacquer and then metallized.

The metallization is advantageously carried out with a thin metal film or a color-changing thin-film coating with the layer sequence reflector / dielectric / absorber.

The Figures 9 and 10 illustrate a further embodiment of the invention, in which several curve representations are visible from different viewing directions as output curves with connected line segments. Specifically, the security element in the exemplary embodiment has a metallic appearance in which the numerical value “50” is visible multiple times one above the other from a first viewing direction and the letter sequence “PL” from a second viewing direction.

Figures 9 (a) to (i) illustrate the visual appearance of a section of a flat motif area 50, which shows as a motif on the one hand the disintegrating numerical value "50" and on the other hand the disintegrating letter sequence "PL", more precisely at different tilt angles. Figure 10 shows the values of the orientation parameter k for this exemplary embodiment in a gray level representation 60.

In this exemplary embodiment, too, the representation of the value number “50” contains the curve representations 14A, 14B already described in detail above in the form of the digits “5” and “0”, respectively. The representation of the letter sequence “PL” contains the curve representations 54A, 54B in the form of the letters “P” and “L”, respectively. Since the output curves in this embodiment cannot be seen from the same, but from different viewing directions should, the output curves are assigned to different values of the orientation parameter k . Specifically, the output curves for the number “50” correspond to a k value of +0.5 and the output curves for the lettering “PL” correspond to a k value of -0.5. In addition, the movement segments 22 of the segments 18 of the value number "50" contain only k values between 0 and 1, while the movement segments 52 of the segments 58 of the letter sequence "PL" only contain k values between -1 and 0, as in FIG Fig. 10 illustrated.

When the motif area 50 is tilted, the in Fig. 9 appearances shown, the values of k = -1 ( Fig. 9 (a) ), k = -0.75 ( Fig. 9 (b) ), k = -0.5 ( Fig. 9 (c) : Letter sequence "PL" visible together), k = -0.25 ( Fig. 9 (d) ), k = 0 ( Fig. 9 (e) : staggered segments of both displays visible at the same time), k = + 0.25 ( Fig. 9 (f) ), k = + 0.5 ( Fig. 9 (g) : Value number "50" visible together), k = + 0.75 ( Fig. 9 (h) ), up to k = + 1 ( Fig. (9i )) correspond.

The segments 18 of the value number "50" are only visible when tilted downwards, since the associated movement segments 22 do not contain any k values greater than 0. Similarly, the segments 58 of the letter sequence “PL” are only visible when tilted upwards, since the associated movement segments 52 do not contain any k values less than 0. Overall, when the motif area is tilted from bottom to top, initially disordered segments 58 result in the letter sequence "PL", which disintegrates again when tilting further, while other disordered segments 22 result in the value number "50", which in turn disintegrates when tilting further upwards ( Figures 9 (a) to (i) ). When tilting back, the movement is reversed.

Such a movement effect is very memorable and dynamic and stands out clearly from known tilting effects. Another peculiarity compared to conventional tilting effects is that in addition to the related representations of the value number "50" and the letter sequence "PL" in certain viewing directions, high-contrast dynamic representations are also visible in the intervening viewing directions, although these hardly or even the original representations can no longer be recognized, but rather show a chaotic structure of disordered segments (e.g. Fig. 9 (b) or 9 (f) ). In particular, in the intermediate state at a value of k = 0, no superimposition of the output curves of the value number "50" and the letter sequence "PL" is visible, but a completely different arrangement of sharply mapped segments 18 and 58.

In such representations, the movement segments 22, 52 and the segments 18, 58 of the two partial representations are particularly advantageously coordinated with one another in such a way that individual segments run continuously from motion segments of the first representation into motion segments of the second representation. The overall representation then contains a common range of motion in which one or more segments move in such a way that they are part of the first representation from the first viewing directions and part of the second representation from the second viewing directions. In this way, the visual impression can be generated that segments of the disintegrating first representation are reassembled to form the new second representation.

In the embodiment of Figures 9 and 10 Such a traversal is realized for the movement segments 52C (left upper end of the letter "P") and 22C (left lower end of the number "5"). The in Fig. 10 The area surrounded by a dashed line therefore represents a combined movement segment 56 with k values from -1 to +1, in which a segment 58C of the letter "P" runs upwards when tilted ( Figs. 9 (c) and 9 (d) ) and becomes a segment 18C of the digit "50" as in FIG Fig. 9 (f) and 9 (g) shown. Figure 9 (e) shows the intermediate state at k = 0, in which both segments 18C, 58C are visible at the same time.

The more segments are both part of the first and part of the second representation, the more likely it is that the impression arises that the second representation is composed of parts of the disintegrating first representation.

List of reference symbols

10

Banknote

12

Security element

14A, 14B

Curve displays

16A, 16B

Tilt directions

18, 18C

Segments

20th

flat motif area

22, 22A, 22B, 22C

Motion segments

24-O, 24-U

Edges of motion segment 22A

26-O, 26-U

Edges of motion segment 22B

30, 32, 34, 36

Facets

40

Grayscale display

50

flat motif area

52, 52C

Motion segments

54A, 54B

Curve displays

56

combined movement segment

58, 58C

Segments

60

Grayscale display

Claims (16)

1. An optically variable security element (12) for securing valuable articles that viewing-angle-dependently displays a motif having at least one curve depiction (14A, 14B) that, from a first viewing direction, is visible as an initial curve having two or more connected, non-collinear segments (18), and that, when the security element (12) is tilted about a predetermined axis, splits into the individual segments (18) in that the segments (18) of the initial curve move alternatingly in different directions away from the initial curve, having

   - an areal motif region (20) having a plurality of optically effective elements (30,32, 34, 36), each of which directs incident light in a preferred direction,

   - the segments (18) of the initial curve in the areal motif region (20) each having associated with it one movement segment (22) in the form of a sub-region of the areal motif region (20), in which sub-region the optically effective elements (30, 32, 34, 36) are arranged and aligned in such a way that, from the first viewing direction, they display the initial curve having the connected segments (18), and that, from viewing directions tilted about the predetermined axis, they display curve depictions in which the segments (18) lie alternatingly in different directions and, with increasing tilt angle, increasingly further away from the initial curve.
2. The security element according to claim 1, characterized in that at least one curve depiction splits into three or more, preferably four or more segments when the security element is tilted.
3. The security element according to claim 1 or 2, characterized in that the initial curve of at least one curve depiction displays an alphanumeric character, a symbol or another information-bearing character.
4. The security element according to at least one of claims 1 to 3, characterized in that the movement segments of the curve depictions have a width that is between 10% and 100%, preferably between 20% and 50% of the dimension of the initial curve of the curve depiction.
5. The security element according to at least one of claims 1 to 4, characterized in that the movement segments of at least one curve depiction all have the same width.
6. The security element according to at least one of claims 1 to 5, characterized in that the optically effective elements are formed by facets that behave according to ray-optics and whose orientation is characterized in each case by an inclination angle α against the plane of the areal motif region and by an azimuth angle θ in the plane of the areal motif region, or in that the optically effective elements are formed by grating fields that behave according to diffraction optics and that have a grating pattern composed of parallel grating lines, or in that the optically effective elements are formed by groove- and/or rib-shaped structural elements that lie adjacent to one another and extend along a longitudinal direction.
7. The security element according to at least one of claims 1 to 6, characterized in that the areal motif region is developed to be reflective such that the initial curve and the split of the initial curve into individual segments are visible in reflection.
8. The security element according to at least one of claims 1 to 7, characterized in that the optically effective elements are formed by reflection elements that are molded in an embossing lacquer and furnished with a reflection- enhancing coating.
9. The security element according to claim 8, characterized in that the reflection- enhancing coating has a color-shift effect, especially in that the coating consists of a thin-film interference layer system having a reflector, a dielectric spacing layer and an absorber.
10. The security element according to at least one of claims 1 to 9, characterized in that the areal motif region is at least partially transmissive such that the initial curve and the split of the initial curve into individual segments are visible in transmission.
11. The security element according to at least one of claims 1 to 10, characterized in that the optically effective elements are formed by transmission elements in the form of transparent or semitransparent diffraction structures, transparent or semitransparent prism structures or transparent or semitransparent microrelief structures.
12. The security element according to at least one of claims 1 to 11, characterized in that the motif includes at least a second curve depiction that, from a second viewing direction, is visible as a second initial curve having two or more connected, non-collinear segments, and that, when the security element is tilted about the predetermined axis, splits into the individual segments in that the segments of the second initial curve move alternatingly in different directions away from the second initial curve, the segments of the second initial curve in the areal motif region each having associated with it one second movement segment in the form of a sub-region of the areal motif region, in which sub-region the optically effective elements are arranged and aligned in such a way that, from the second viewing direction, they display the second initial curve having the connected segments, and that, from viewing directions tilted about the predetermined axis, they display curve depictions in which the segments lie alternatingly in different directions and, with increasing tilt angle, increasingly further away from the second initial curve, especially in that the movement segments of the first and second curve depiction do not overlap.
13. The security element according to claim 12, characterized in that the first and second viewing direction include an angle of at least 5°, preferably at least 10° and particularly preferably at least 20°, and/or in that at least one segment of the first curve depiction is also a segment of the second curve depiction such that, when the security element is tilted, the second curve depiction is at least partially composed of segments of the split first curve depiction.
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 or the like.
15. A data carrier having a security element according to one of claims 1 to 14.
16. A method for manufacturing an optically variable security element (12) according to one of claims 1 to 14, in which

    - a desired initial curve having two or more connected, non-collinear segments (18) is defined,

    - for each of the segments (18) of the initial curve, movement segments (22) are defined in which the segments (18) of the initial curve move when the security element is tilted (12), and

    - in an areal motif region (20) in the defined movement segments (22), optically effective elements (30, 32, 34, 36) are arranged and aligned in such a way that, from the first viewing direction, they display the initial curve having the connected segments (18), and that, from viewing directions tilted about the predetermined axis, they display curve depictions in which the segments (18) lie alternatingly in different directions and, with increasing tilt angle, increasingly further away from the initial curve.

Images