EP3823840B1 - Security element comprising a lenticular image - Google Patents

Description

The invention relates to a security element for securing security papers, value documents and other data carriers, with a lenticular image which contains a lenticular grid made up of a plurality of microlenses and a radiation-sensitive motif layer arranged at a distance from the lenticular grid, wherein the radiation-sensitive motif layer contains a plurality of transparency regions generated by the action of radiation in a motif region.

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 allow the authenticity of the data storage media to be verified and at the same time serve as protection against unauthorized reproduction.

Security elements with viewing angle-dependent effects play a special role in authenticity assurance, as these cannot be reproduced even with the most modern copying machines. The security elements are equipped with optically variable elements that give the viewer a different image impression at 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, it is known to provide the data carriers with laser-engraved tilting images for security purposes. In this case, two or more different markings, such as a serial number and an expiration date, are displayed at different angles by an arrangement of cylindrical Lenses are laser engraved into the data carrier. The laser radiation creates a local blackening of the data carrier body, which makes the engraved markings visually visible. When viewed, depending on the viewing angle, only the marking engraved from this direction is visible, so that tilting the data carrier perpendicular to the axis of the cylindrical lenses creates an optically variable tilting effect.

In the case of tilting images, it is further desirable to increase the security against forgery if the images visible from different directions have different colors.

There are several known methods for producing tilted images, but they all have certain disadvantages. Basically, the known methods can be differentiated according to whether the microimages in a motif layer are produced with or without the aid of the lens grid of the tilted image.

Without the aid of the lenticular grid, the microimages can be printed or embossed, for example. These manufacturing variants are generally very cost-effective, but it is generally not possible, particularly with the very thin layer structures that are important in security printing, to arrange the microimages in such a precise register with the lenticular grid that the different images always appear at the same angle, so that, for example, when looking at several banknotes with the same tilted image next to each other, all banknotes show the same image from a certain angle.
an image is written into a motif layer. The motif layer is either exposed to laser radiation through a mask or a laser beam is scanned over the motif layer to write a desired motif. In both process variants, the motif is placed under the

Lenses in focus and is therefore always perfectly registered with the lenses. It is also ensured that the inscribed motif will later be visible from exactly the direction from which it was exposed with the laser beam. The disadvantage, however, is that laser engraving processes are often difficult to implement on a large scale. For example, lasering millimeter-sized motifs using a mask or scanner in film production represents a major and costly technical challenge given the film widths and process speeds usual for security applications. This is particularly true when a different image has to be lasered into the motif layer in order to create two or more different, direction-dependent motifs visible from two or more different directions.

WO 2010/115235 A1 , WO 2014/127403 A1 and EP 1 983 473 A1 show optically variable security elements. WO 2017/097430 A1 shows the preamble of claim 1.

Proceeding from this, the invention is based on the object of specifying a security element of the type mentioned at the outset which has a visually attractive appearance and is easy to manufacture.

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

The invention includes a security element as defined in claim 1.

The contrast sub-layer is preferably formed by a brightly colored or dark, especially black, print layer. Bright colors are all colors that are not white, black or gray. For a high contrast, bright colors with a high saturation, for example a rich red, blue or green, are preferred.

The color sublayer advantageously contains interference pigments, pearlescent pigments and/or liquid crystal pigments as color-imparting effect pigments. The color sublayer can in particular be an Iriodin ^® printing layer with mica-based pearlescent pigments. Such pearlescent pigments produce gloss and color effects whose color scale ranges from silver-white to red and bronze-colored earth tones to gold luster. According to current understanding, the color effects arise from an interplay of transparency, light refraction and multiple reflection on the sublayers of the pigments. The pearlescent pigments usually consist of thin mica flakes that are covered by a thin metal oxide layer. Other interference pigments can also contain other carrier materials and several different coatings.

The contrast sub-layer is located behind the color sub-layer when viewed from the lens grid and therefore forms a background layer for the color sub-layer when viewed from the direction of view. While the radiation-sensitive motif layer can in principle also have three or more sub-layers, an advantageous design provides that the radiation-sensitive The motif layer only consists of the two sub-layers mentioned, namely the color sub-layer and the contrast sub-layer.

The color sub-layer and/or the contrast sub-layer are advantageously applied with a color layer thickness between 0.5 and 10 g/m ² , in particular between 1 and 2 g/m ² .

In a preferred embodiment, the contrast sublayer and/or the color sublayer are formed in the form of patterns, characters or a coding.

Preferably, at least the contrast sub-layer of the motif layer is removed in the transparent areas. The color sub-layer can also advantageously be removed in the transparent areas, or it can also advantageously be retained in the transparent areas. Both variants each have certain advantages, which are described in more detail below in connection with the exemplary embodiments.

• die Transparenzbereiche jeweils passergenau zu den Mikrolinsen des Linsenrasters angeordnet sind, und
• die strahlungssensitive Motivschicht außerhalb der durch Strahlungseinwirkung erzeugten Transparenzbereiche opak ist und in dem Motivbereich in Form eines ersten Motivs strukturiert ist, so dass das erste Motiv bei Betrachtung des Sicherheitselements aus einer ersten Betrachtungsrichtung durch das Linsenraster als erstes Erscheinungsbild sichtbar ist.

In a preferred more specific embodiment, it is further provided that the lenticular image shows at least two different appearances from different viewing directions, whereby

• the transparency areas are arranged in precise register with the microlenses of the lens grid, and
• the radiation-sensitive motif layer is opaque outside the transparency areas created by the action of radiation and is structured in the motif area in the form of a first motif, so that the first motif consists of a first The first appearance visible when viewed through the lens grid is the direction of view.

Even if the transparency areas are always arranged in precise register with the microlenses, this does not mean that each microlens has to be assigned a transparency area. Rather, in an advantageous embodiment, there is a partial area in which there are no transparency areas in the motif layer. The partial area without transparency areas is advantageously designed in the form of another motif that lies completely within the motif formed by the motif layer itself. In this way, tilt effects that are in precise register can be created, as described in more detail below.

In a preferred embodiment, the radiation-sensitive motif layer is laser-sensitive and is ablated in particular by laser radiation.

The refractive effect of the microlenses of the lens grid defines a focal plane, with the radiation-sensitive motif layer advantageously being arranged essentially in this focal plane. The motif layer does not have to lie exactly in the focal plane, but in some designs can lie up to half a focal length above or below the focal plane. Such a defocused arrangement of the motif layer can be particularly advantageous if a particularly low thickness of the security element is to be achieved or a particularly large area under the respective microlenses is to be made transparent. By arranging the motif layer outside the focal plane, the viewing angles from which the appearances are visible can also be influenced. and in particular enlarged. A large viewing angle range is a particularly desirable product feature of the security elements described.

In an advantageous embodiment, it is provided that the lens grid has or represents a one-dimensional arrangement of microlenses, in particular cylindrical lenses. It can also advantageously be provided that the lens grid has or represents a two-dimensional arrangement of microlenses, in particular spherical or aspherical lenses.

In this description, microlenses are lenses whose size in at least one lateral direction is below the resolution limit of the naked eye. The microlenses can in particular be cylindrical, but the use of spherical or aspherical lenses is also possible. The latter preferably have a diameter between 5 µm and 300 µm, in particular between 10 µm and 50 µm, particularly preferably between 15 µm and 20 µm. Micro-cylindrical lenses preferably have a width between 5 µm and 300 µm, in particular between 10 µm and 50 µm, particularly preferably between 15 µm and 20 µm. The length of the micro-cylindrical lenses is arbitrary; for example, when used in security threads or transfer elements, it can also correspond to the total width of the thread or transfer element and be several millimeters or several centimeters.

In an advantageous embodiment, a second motif layer is arranged on the side of the radiation-sensitive motif layer facing away from the lens grid, which is structured in the form of a second motif, so that the The second motif is visible as a second appearance when the security element is viewed from a second viewing direction through the lens grid and the transparency areas of the radiation-sensitive motif layer.

The second motif layer is advantageously formed by a brightly colored or dark, in particular black, print layer, whereby it is currently preferred that the second motif layer has the same color or the same shade as the contrast sub-layer.

Advantageous visual effects can be achieved in particular if the second motif layer, apart from the transparency areas created by the effect of radiation, lies completely within the area of the contrast sub-layer.

According to a further, likewise advantageous embodiment, one or more transparent layers are arranged on the side of the radiation-sensitive motif layer facing away from the lenticular grid, so that when the security element is viewed from a second viewing direction through the lenticular grid and the transparency areas of the radiation-sensitive motif layer, a background lying beneath the security element is visible as a second appearance.

The invention also includes a data carrier, in particular a value document, a security paper, an identity card, a branded article or the like, with a security element of the type described.

Such a data carrier can in particular contain a security element without a second motif layer, in which in the manner described above one or more transparent layers are arranged on the side of the radiation-sensitive motif layer facing away from the lenticular grid. It is further provided that the data carrier is provided in a partial area with a second motif layer that is structured in the form of a second motif. The security element is then arranged with the lenticular grid and the transparency areas above the second motif layer, so that the second motif is visible as a second appearance when the security element is viewed from a second viewing direction through the lenticular grid and the transparency areas of the radiation-sensitive motif layer. This makes it easy to produce data carriers with tilt images that show a general, generic motif (first motif) from a first viewing direction and an individualized motif (second motif) from a second viewing direction, as explained in more detail below.

The invention also includes a method for producing a security element as defined in claim 13.

• die Transparenzbereiche in der strahlungssensitiven Motivschicht passergenau zu den Mikrolinsen des Linsenrasters erzeugt werden, und
• die strahlungssensitive Motivschicht außerhalb der durch Strahlungseinwirkung erzeugten Transparenzbereiche opak und in Form eines ersten Motivs strukturiert ausgebildet wird, so dass das erste Motiv bei Betrachtung des Sicherheitselements aus einer ersten Betrachtungsrichtung durch das Linsenraster als erstes Erscheinungsbild sichtbar ist.

In a preferred more specific method, the lenticular image shows at least two different appearances from different viewing directions, wherein in the method

• the transparency areas in the radiation-sensitive motif layer are created in precise register with the microlenses of the lens grid, and
• the radiation-sensitive motif layer is opaque and structured in the form of a first motif outside the transparency areas created by the action of radiation, so that the first motif is visible as the first appearance when the security element is viewed from a first viewing direction through the lens grid.

In an advantageous process, the radiation-sensitive motif layer is exposed to laser radiation through the lens grid in order to create the transparent areas. The radiation-sensitive motif layer is advantageously ablated by the laser radiation.

• Frequenz: 10 - 100 kHz, bevorzugt 10-20 kHz
• Vorschub: 10-2500 mm/s, bevorzugt 100-300 mm/s
• Leistung: 0,1-100%, bevorzugt 0,1-3,5% bei einem 10 W-Laser.

IR or NIR lasers (NIR: wavelength 0.78 - 3 µm) are advantageously used as laser sources, especially lasers in the IR-A range (wavelength 0.78 - 1.4 µm), for example at a wavelength of around 1064 nm. With an NIR laser, for example of the wavelength mentioned, the following parameters are suitable for ablation:

• Frequency: 10 - 100 kHz, preferably 10-20 kHz
• Feed: 10-2500 mm/s, preferably 100-300 mm/s
• Power: 0.1-100%, preferably 0.1-3.5% for a 10 W laser.

A security element according to the invention can also contain more than two representations that are visible from more than two different viewing directions.

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 was omitted in order to increase clarity.

Fig. 1

in schematischer Darstellung eine Banknote mit einem erfindungsgemäßen Sicherheitselement, das ein Kippbild mit zwei unterschiedlichen Erscheinungsbildern enthält,

Fig. 2

schematisch den Schichtaufbau des Sicherheitselements der Fig. 1 im Querschnitt,

Fig. 3

eine Aufsicht auf das Sicherheitselement der Fig. 2 ohne das Linsenraster und damit ohne die fokussierende Wirkung der Mikrolinsen,

Fig. 4 bis 7

die Herstellung des Sicherheitselements der Figuren 2 und 3, wobei (a) jeweils einen Zwischenschritt bei der Herstellung des Sicherheitselements und (b) das Erscheinungsbild des jeweiligen Zwischenprodukts in Aufsicht ohne das Linsenraster und damit ohne die fokussierende Wirkung der Mikrolinsen zeigt,

Fig. 8

schematisch ein erfindungsgemäßes Sicherheitselement, bei dem auf die zweite Motivschicht verzichtet wurde,

Fig. 9

ein Sicherheitselement mit passgenauem Kippeffekt nach einem weiteren Ausführungsbeispiel der Erfindung im Querschnitt,

Fig. 10

in (a) und (b) das Erscheinungsbild des Sicherheitselements der Fig. 9 aus zwei Betrachtungsrichtungen,

Fig. 11

ein Sicherheitselement mit passgenauem Kippeffekt nach einem weiteren Ausführungsbeispiel der Erfindung im Querschnitt, und

Fig. 12

in (a) und (b) das Erscheinungsbild des Sicherheitselements der Fig. 11 aus zwei Betrachtungsrichtungen.

They show:

Fig.1

in schematic representation a banknote with a security element according to the invention, which contains a tilting image with two different appearances,

Fig. 2

schematically the layer structure of the security element of the Fig.1 in cross section,

Fig.3

a supervision of the safety element of the Fig. 2 without the lens grid and thus without the focusing effect of the microlenses,

Fig. 4 to 7

the production of the security element of the Figures 2 and 3 , where (a) each intermediate step in the production of the security element and (b) shows the appearance of the respective intermediate product in plan view without the lens grid and thus without the focusing effect of the microlenses,

Fig.8

schematically shows a security element according to the invention in which the second motif layer has been omitted,

Fig.9

a security element with a precisely fitting tilting effect according to a further embodiment of the invention in cross section,

Fig.10

in (a) and (b) the appearance of the security element of the Fig.9 from two perspectives,

Fig. 11

a security element with a precisely fitting tilting effect according to a further embodiment of the invention in cross section, and

Fig. 12

in (a) and (b) the appearance of the security element of the Fig. 11 from two perspectives.

The invention will now be explained using the example of security elements for banknotes. Figure 1 shows a schematic representation of a banknote 10 which is provided with a security element 12 according to the invention in the form of a glued-on transfer element. In the exemplary embodiment, the security element 12 represents a tilted image which, depending on the viewing direction, shows one of two different appearances 14A, 14B.

However, the invention is not limited to the transfer elements shown for illustration purposes on banknotes, but can also be used, for example, with security threads, wide security strips or cover films that are arranged over an opaque area, a window area or a continuous opening of a data carrier.

Returning to the presentation of the Fig.1 In the exemplary embodiment, the two appearances are formed by a two-color representation 14A of the value number "50" and a representation 14B of two colored rectangles, but it is understood that in practice the appearances typically represent more complex motifs, such as geometric patterns, portraits, coding, numbering, architectural, technical or natural motifs. When the banknote 10 is tilted 16 or the viewing direction is changed accordingly, the appearance of the security element 12 changes back and forth between the two appearances 14A, 14B.

While lenticular images with tilting images are known as such, the present invention provides a specially designed lenticular image in which the motifs shown are incorporated into the motif layer of the lenticular image in a particularly simple and yet highly precise manner.

Figure 2 shows schematically the layer structure of the security element 12 according to the invention in cross section, wherein only the parts of the layer structure required for explaining the functional principle are shown. Figure 3 shows a top view of the security element 12 without the lens grid and thus without the focusing effect of the microlenses.

The Figures 2 and 3 show the finished security element 12, but for understanding the complex layer structure and the interaction of the individual layers, the detailed description of the manufacture of the security element with reference to the Figures 4 to 7 helpful.

The security element 12 contains a carrier substrate 22 in the form of a transparent plastic film, for example a polyethylene terephthalate (PET) film approximately 20 µm thick. The carrier substrate 22 has opposite first and second main surfaces, wherein the first main surface is provided with a lens grid 24 made up of a plurality of essentially cylindrical microlenses 26.

The thickness of the carrier substrate 22 and the curvature of the focusing lens surfaces of the microlenses 26 are coordinated with one another in such a way that the focal length of the microlenses 26 essentially corresponds to the thickness of the carrier substrate 22. The focal plane of the microlenses 26 then essentially coincides with the second, opposite main surface of the carrier substrate 22. As explained above, in some embodiments it may also be useful not to allow the focal plane to coincide with the second main surface of the carrier substrate, for example in order to produce particularly thin security elements.

A laser-sensitive motif layer 30 is arranged on the second main surface of the carrier substrate 22, which in the exemplary embodiment shown consists of two sub-layers, namely a color sub-layer 32 containing color-imparting effect pigments and a black contrast sub-layer 34. Specifically, the color sub-layer 32 in the exemplary embodiment is a Iriodin ^® color, i.e. a printing ink with mica-based pearlescent pigments. The contrast partial layer 34 is formed in the example by a black printing ink. Without a contrast layer in the background, the color partial layer 32 with the pearlescent pigments appears transparent and is practically invisible when viewed. In the areas where the contrast partial layer is present and forms a dark background, the pearlescent pigments appear with strong color and rich colors.

The motif layer 30 also contains a large number of parallel, linear transparency areas in the form of linear recesses 40, which were created in the manner described in more detail below in precise registration with the microlenses 26 of the lens grid 24. The areas of the motif layer 30 between the recesses 40 form remaining material areas 42, which are also linear and in precise registration with the microlenses 26. In the exemplary embodiment, the linear recesses 40 and the linear material areas 42 have the same width, but in general the recesses and the material areas can also have different widths.

In the remaining material areas 42, the motif layer 30 is opaque and structured in the form of a first motif, in the embodiment in the form of the value number "50". Specifically, the color sub-layer 32 represents the number "50" with the colored appearance of the pearlescent pigments against a dark background, while the areas in which only the contrast sub-layer 34 is present form a non-colored, black environment for the value number "50".

Due to the focusing effect of the microlenses 26, a viewer looks from a first viewing direction 50 at the remaining material areas 42 of the motif layer 30 and therefore perceives the colored value number "50" against a dark background as appearance 14A. The recesses 40 are not visible from the viewing direction 50, so that the representation of the value number "50" appears to be full-surface for the viewer.

From a second viewing direction 52, the viewer looks at the recesses 40 in the motif layer 30 due to the focusing effect of the microlenses 26, so that the motif layer 30 is not visible from this viewing direction and the perceived appearance depends on the further design of the security element in the recesses 40. In the exemplary embodiment shown, on the side of the motif layer 30 facing away from the lens grid 24 there is a second motif layer in the form of a print layer 60, which is structured in the form of a second motif. A simple motif made up of two differently colored rectangles 62, 64 is shown as the second motif for illustration purposes, but it is understood that single-colored or even arbitrarily complex multi-colored motifs can also be created here as desired.

When viewed from the second viewing direction 52, the viewer thus looks through the recesses of the first motif layer 30 onto the second motif layer 60 and therefore perceives the two colored rectangles 62, 64 as appearance 14B.

The security element 12 typically contains further layers 66, such as protective, covering or additional functional layers, which, however, are not essential here and are therefore not described in detail. One or more of the further layers 66 can be opaque and form a background for the representation of the second motif layer 60, or the further layers can be transparent or translucent and, if the second motif layer does not cover the entire surface, allow a view through the security element 12 in some areas.

The second motif layer 60 can be full-surface, or, as in the embodiment of the Figures 2 and 3 , are only partially present and therefore allow a view of a background layer lying beneath the security element 12 in the areas outside the motif layer 60. The background layer can be formed, for example, by the substrate of the banknote 10 (in Fig. 2 indicated by dashed lines) or another data carrier on which the security element 12 is applied. The background layer can be single-colored or structured itself and, for example, contain information that can be recognized in the recesses 40 from the viewing direction 52. The security element 12 can also be present in a window area of a data carrier, so that the transparent areas lying outside the motif layer 60 represent see-through areas in the security element 12.

The manufacture of the security element 12 will now be described with reference to the Figures 4 to 7 explained, wherein the figure part (a) of the figures shows an intermediate step in the production of the security element and the figure part (b) shows the appearance of the respective intermediate product in plan view without the lens grid 24 and thus without the focusing effect of the microlenses 26.

With reference first to Fig.4 A carrier substrate 22 in the form of an approximately 20 µm thick polyethylene terephthalate (PET) film is provided and is placed on a first main surface is preferably provided with a lens grid 24 made of a plurality of essentially cylindrical microlenses 26 with a width b = 15 µm by embossing. Then, on the opposite second main surface of the carrier substrate 22, an Iriodin ^® printing layer with mica-based pearlescent pigments with a basis weight of 1.5 g/m ² in the form of the value number "50" is printed in the desired original size as a color partial layer 32. As shown in the top view of the Fig. 4(b) As shown, after this process step, the color partial layer 32 structured in the form of the value number "50" is present on the carrier substrate 22.

Subsequently, as a second partial layer of the motif layer 30, a black print layer 34 is printed over the entire surface of the structured color partial layer 32, as shown in Fig. 5(a) It is important that the black print layer 34 forms a contrast layer for the pearlescent pigments of the color sub-layer 32, and these therefore appear strongly colored against the background of the print layer 34. As can be seen in the top view of the Fig. 5(b) As shown, after this process step, the motif layer 30 with the colored value number "50" (reference number 32) is present against a dark background 34. The print layer 34 can in particular be printed with a motif-shaped outline, for example as a circular disk, star or the like. The term "full-surface" means that the print layer is not designed as a grid, but fills the entire area within its outline.

In the next process step, the surface of the motif layer 30 is exposed to near-infrared laser radiation 70 over a large area from a predetermined direction through the lens grid 24, as shown in Fig. 6(a) The laser radiation 70 is focused linearly by the cylindrical microlenses 26 onto the motif layer 30 arranged on the second main surface of the carrier substrate 22 and ablates the color sub-layer 32 and the black contrast layer 34, so that linear recesses 40 are created in the motif layer 30.

Black print layers such as the contrast sub-layer 34 show a high absorption for laser radiation in the near infrared and can be easily ablated using a wide range of laser parameters. In the exemplary embodiment, the color sub-layer 32 with the effect pigments is also removed either by its own absorption or at least by the heat generated when the laser radiation is absorbed by the adjacent black print layer 34. However, even in variants in which the color sub-layer 32 is not physically removed, it no longer appears to be present to the viewer after the laser exposure, since the color sub-layer 32 is practically no longer visible after the ablation of the contrast sub-layer 34 behind it due to its transparency. Designs that exploit this effect are described in more detail below.

In order to be able to cleanly ablate the partial layers, the color particles of the color partial layer and the contrast partial layer should be easily removed. The foil is therefore advantageously not placed on a substrate with the layers to be ablated, but is lasered "in suspension". As shown in the top view of the Fig. 6(b) As shown, after this process step, the motif layer 30 with the colored value number "50" (reference number 32) and the dark background 34 is only present in the remaining material areas 42. Between the material areas 42, transparency areas 40 were created by the laser exposure, in which the intermediate product is transparent.

In a variant of the invention, the security element 12 can already be fed into the final production after this process step and, for example, be provided with a transparent protective layer on the second main surface, as described below in connection with Fig.8 described in more detail. In the invention variant of the present embodiment ( Fig. 7(a) ), on the other hand, a second motif layer 60 is printed onto the first motif layer 30 provided with recesses 40, which is structured in the form of a second motif with two colored rectangles 62, 64. After this process step, the security element now has Fig. 7(b) shown two structured motif layers 30 and 60, respectively, whose motifs are each viewed from the viewing directions 50, 52 ( Fig. 2 ) are visible. As far as can be seen when viewing, both motifs are also arranged in precise register with the microlenses 26 of the lens grid 24, although only a single laser exposure step was required to produce them.

At the Fig.8 In the variant shown, the second motif layer 60 was omitted and at most transparent layers, for example a transparent protective or covering layer and/or a transparent adhesive layer, were applied to the first motif layer 30. The security element 80 thus created shows, when viewed from a first viewing direction, the first motif already described above, formed by the first motif layer 30, and from a second viewing direction in the recesses 40 of the first motif layer 30 provides a view of a background layer.

In this way, it is particularly easy to produce data carriers with tilting images that show a general, generic motif from a first viewing direction and an individualized motif from a second viewing direction. For example, the security element 80 for the It is intended for use in identity documents 82 and its motif layer 30 shows a national coat of arms as the first generic motif. Since the security element 80 itself only shows the generic motif "national coat of arms", it can be used unchanged for all similar identity documents 82.

A motif present in a data area 84 of the ID document 82, for example a passport photo of the holder, serves as the individualized motif. This individualized motif is different for each ID document 82. The security element 80 is then glued to the data area 84 with the cut-out motif layer 30, 40, so that the state coat of arms of the motif layer 30 is visible from the first viewing direction and the individualized motif of the data area 84 is visible from the second viewing direction.

Figures 9 and 10 show a further embodiment of a security element 90 according to the invention with a precisely fitting tilting effect, for the production of which the significantly different absorption of the color sub-layer 32 and the contrast sub-layer 34 is specifically exploited. With reference first to the cross-sectional representation of the Fig.9 The safety element 90 is basically like the safety element 12 of the Fig. 2 and contains a carrier substrate 22 which is provided with a lens grid 24 on one main surface and with a first, laser-sensitive motif layer 30 on the opposite main surface. In a motif-shaped partial area 92, a second motif layer 94 is arranged above the first motif layer 30.

The first motif layer 30 consists of two sub-layers, namely a color sub-layer 32 containing color-imparting effect pigments, for example a printing ink with mica-based pearlescent pigments, and a black contrast sub-layer 34, which is formed by a black printing ink.

The colour sub-layer 32 was used as motif 100 in the form of the continuous lettering "fünfzigeuro" ( Fig. 10(a), 10(b) ) printed on the carrier foil 22, as is generally the case with Fig.4 Then the contrast sub-layer 34 was applied as a continuous layer in the form of a second motif, in the embodiment in the form of a circular disk 102 ( Fig. 10(a) ) printed on it. The cross section of the Fig.9 shows an area of the security element 90 within the printed circular motif 102.

The layer sequence 32, 34 was then exposed to NIR laser radiation over a large area through the lens grid 24, as is generally the case with Fig.6 described, wherein the laser parameters are selected such that only the black contrast sub-layer 34 is ablated by the laser radiation, but not the color sub-layer 32, which is largely transparent to the laser radiation. Due to the significantly higher absorption of the black contrast sub-layer 34, such laser parameters can always be found without any problem. If the laser power is not raised too far above the ablation threshold of the contrast sub-layer 34, the heat conduction to the color sub-layer 32 is also kept sufficiently low to avoid ablation of the color sub-layer 32. As a result, after this process step, the motif layer 30 is present on the one hand with the color sub-layer 32 not ablated and with the contrast sub-layer 34 partially ablated. Specifically, the contrast sub-layer 34 is ablated in the transparent areas 40 and left in the material areas 42, while the color sub-layer 32 is retained in both areas 40, 42.

Then, in a partial area 92 of the circular motif 102, a second motif layer 94 in the form of a black print layer in the form of another motif, in the embodiment in the form of a star 104 ( Fig. 10(b) ) is applied. Further protective, covering or functional layers may follow, but are not essential for the present explanation.

The resulting appearance of the security element 90 from two viewing directions 106, 108 is shown in Fig. 10(a) and 10(b) respectively.

From a first viewing direction 106, the viewer looks at the material areas 42 in which the contrast sub-layer 34 was left standing due to the focusing effect of the microlenses 26 within the circular motif 102. There, the contrast sub-layer 34 represents a dark background for the lettering 100 "fifty euros" formed by the color sub-layer 32, so that the lettering appears with rich colors against the dark background of the circular motif 102, as in Fig. 10(a) illustrated. In the area 112 outside the circular motif 102, the dark background is missing, so that any partial color layer 32 present there remains practically invisible.

From a second viewing direction 108, however, the viewer looks at the transparency areas 40 of the circular motif 102, in which the contrast sub-layer 34 has been removed but the color sub-layer 32 has been left, due to the focusing effect of the microlenses 26. In the sub-area 92, which is in the form of the star motif 104, the second motif layer 94 forms a dark background for the lettering 100, so that the colored lettering "fifty euros" is still visible there. In the area 114 outside the star motif 104, however, there is no dark background layer from this viewing direction, so that the Color sub-layer 32 does not appear ( Fig. 10(b) ). The area previously occupied by the circular motif 102 is in Fig. 10(b) shown in dashed lines.

As a result, when tilted from the first viewing direction 106 into the second viewing direction 108, the security element 90 shows a tilting effect from the circle motif 102 to the star motif 104 with the lettering 100 arranged precisely within the motifs 102, 104, which is always visible in practically the same place.

In some designs, the color sub-layer 32 can be slightly bleached or its color effect can be changed by the laser exposure when the contrast sub-layer 34 is removed, so that the color impression of the lettering 100 in the star motif 104 differs from the color impression of the lettering 100 in the circle motif 102. The perfect registration of the lettering in both viewing directions is unaffected by this.

Instead of the black print layers 34, 94, print layers with other colors can also be used, whereby darker or stronger colors, for example a strong red, a dark blue or a deep green, bring out the effect pigments better. In combination with the color effect of the effect pigments, a colored mother-of-pearl shimmer is created with a combination of the color of the contrast sub-layer 34 or the second motif layer 94 and the color of the effect pigments of the color sub-layer 32.

A to the embodiment of the Figs. 9 and 10 alternative design is in Figures 11 and 12 illustrated by the security element 120, which shows closely related visual effects, but has a different layer structure and is manufactured in a different way.

With reference first to the cross-sectional representation of the Fig. 11 the security element 120 contains a carrier substrate 22 which is provided on one main surface with a lens grid 24 and on the opposite main surface with a first, laser-sensitive motif layer 30.

The laser-sensitive motif layer 30 consists of two sub-layers, namely a color sub-layer 32 in the form of a printing ink with mica-based pearlescent pigments, and a black contrast sub-layer 34, which is formed by a black printing ink. As with the design of the Fig.9 the color sub-layer 32 was printed as a motif 100 in the form of the continuous lettering "fünfzigeuro" (Fig. 11(a), 11(b)). Then the contrast sub-layer 34 was printed as a continuous layer in the form of a second motif, in the embodiment in the form of a circle 102 ( Fig. 12(a) ) printed on it. The cross section of the Fig. 11 shows an area of the security element 120 within the printed circular motif 102.

Then the layer sequence 32, 34 was exposed to NIR laser radiation through the lens grid 24, whereby, as in the design of Figures 9 and 10, the laser parameters can be selected so that only the black contrast sub-layer 34 is ablated by the laser radiation, but not the color sub-layer 32, which is largely transparent to the laser radiation. In contrast to the design of the Figures 9, 10 However, the motif layer 30 is exposed to laser radiation over a large area over the entire surface of the circular motif 102. Rather, the motif layer 30 is not exposed to laser radiation in a partial area 122 of the circular motif 102, which is in the form of a star 104. The motif layer is only exposed to laser radiation in the area 124 that lies outside the partial area 122.

The resulting appearance of the security element 120 from two viewing directions 106, 108 is shown in Fig. 12(a) or 12(b) and is substantially the same as that used in connection with Figures 9, 10 described appearance.

From a first viewing direction 106, the viewer looks, due to the focusing effect of the microlenses 26 within the circular motif 102, at those material areas 42 which either lie within the unexposed area 122 or which lie in the exposed area 124 but in which the contrast sub-layer 34 was left standing. Within the circular motif 102, the contrast sub-layer 34 therefore represents a dark background for the lettering "fifty euros" formed by the color sub-layer 32, so that the lettering 100 appears with rich colors against the dark background of the circular motif 102, as in Fig. 12(a) shown. In the area 112 outside the circular motif 102, the dark background is missing, so that a partial color layer 32 that may be present there remains practically invisible.

From a second viewing direction 108, however, the viewer looks at the lasered transparency areas 40 in which the contrast partial layer 34 was removed due to the focusing effect of the microlenses 26 within the circular motif 102 in the area 124. Since there is no dark background layer in the area 124, the color partial layer 32 is not recognizable to the viewer. In the unexposed partial area 122, which is in the form of the star motif 104, no transparency areas were created, so that the contrast partial layer 34 there represents a dark background for the lettering 100 and this is therefore appears in color. As a result, the star motif 104 with the colored lettering "fünfzigeuro" is visible from the viewing direction 108.

When tilting from the first viewing direction 106 to the second viewing direction 108, a tilting effect occurs from the circle motif 102 to the star motif 104 with the lettering 100 arranged precisely within the motifs 102, 104 and always visible in the same place.

The variant of the Figures 11, 12 requires compared to the variant of the Figures 9, 10 a stronger lateral control of the laser radiation since only the area 124 outside the star motif 104 is exposed to laser radiation. On the other hand, the setting of the laser parameters is not critical in this variant since when the transparent areas 40 are exposed, not only the contrast sub-layer 34 but also the color sub-layer 32 can be removed.

A motif such as the star motif can also be created by a shaped laser beam, as is the case in EP3015279A1 is described in more detail. In particular, the cross-section of the laser beam in these variants corresponds to the motif. A plurality of microlenses of the lens grid are simultaneously exposed to the laser beam with the motif-shaped beam cross-section.

List of reference symbols

10

Banknote

12

Security element

14A, 14B

Appearances

16

Tilt direction

22

Carrier substrate

24

Lenticular grid

26

Microlenses

30

laser-sensitive motif layer

32

Color sub-layer

34

Metal sublayer

40

Recesses

42

areas of material left standing

50.52

Viewing directions

60

second motif layer

62, 64

colored rectangles

66

additional layers

70

Laser radiation

80

Security element

82

Identification document

84

Data area

90

Security element

92

Sub-area

94

second motif layer

100

Motif continuous lettering

102

Circle motif

104

Star motif

106,108

Viewing directions

112

Area outside the circle motif

114

Area outside the star motif

120

Security element

122

unaffected area

124

apply partial area

Claims (15)

1. Security element (12) for safeguarding security papers, valuable documents and other data carriers, comprising

   - a lens grid image containing a lens grid (24) composed of a plurality of microlenses (26), and a radiation-sensitive motif layer (30) arranged at a distance from the lens grid (24),

   - wherein the radiation-sensitive motif layer (30) contains, in a motif region, a multiplicity of transparency regions (40) which are generated by the action of radiation through the lens grid (24),

   - wherein the radiation-sensitive motif layer (30) has, at least in the motif region, a colour sublayer (32) and a contrast sublayer (34),
   characterized in that

   - the colour sublayer (32) comprises colour-imparting effect pigments which appear coloured against the background of the contrast sublayer (34) and which appear transparent without a contrast layer.
2. Security element (12) according to Claim 1, characterized in that the contrast sublayer (34) is formed by a chromatic or dark, in particular black, printed layer.
3. Security element (12) according to Claim 1 or 2, characterized in that the colour sublayer (32) contains interference pigments, pearlescent pigments and/or liquid crystal pigments as colour-imparting effect pigments.
4. Security element (12) according to at least one of Claims 1 to 3, characterized in that the colour sublayer (32) and/or the contrast sublayer have/has a colour layer thickness of between 0.5 and 10 g/m², in particular between 1 and 2 g/m².
5. Security element (12) according to at least one of Claims 1 to 4, characterized in that the contrast sublayer (34) and/or the colour sublayer (32) are/is embodied in the form of patterns, characters or a coding.
6. Security element (12) according to at least one of Claims 1 to 5, characterized in that at least the contrast sublayer of the motif layer (30) is removed in the transparency regions; and preferably

   the colour sublayer (32) is likewise removed in the transparency regions; or

   the colour sublayer (32) is maintained in the transparency regions.
7. Security element (12) according to at least one of Claims 1 to 6, characterized in that the lens grid image shows at least two different appearances from different viewing directions, wherein

   - the transparency regions (40) are each arranged with register accuracy with respect to the microlenses (26) of the lens grid, and

   - the radiation-sensitive motif layer (30) is opaque outside the transparency regions (40) generated by the action of radiation and is structured in the form of a first motif in the motif region, such that the first motif is visible as a first appearance when the security element (12) is viewed from a first viewing direction through the lens grid (24).
8. Security element (12) according to at least one of Claims 1 to 7, characterized in that the radiation-sensitive motif layer (30) is laser-sensitive.
9. Security element (12) according to at least one of Claims 1 to 8, characterized in that the lens grid (24) has or constitutes a one-dimensional arrangement of microlenses (26), in particular cylindrical lenses, or in that the lens grid (24) has or constitutes a two-dimensional arrangement of microlenses (26), in particular spherical or aspherical lenses.
10. Security element (12) according to at least one of Claims 1 to 9, characterized in that a second motif layer (60) structured in the form of a second motif is arranged on the side of the radiation-sensitive motif layer (30) facing away from the lens grid (24), wherein preferably the second motif is visible as a second appearance when the security element (12) is viewed from a second viewing direction through the lens grid (24) and the transparency regions (40) of the radiation-sensitive motif layer (30); wherein preferably

    the second motif layer (60) is formed by a chromatic or dark, in particular black, printed layer, preferably in that the second motif layer has the same colour as the contrast sublayer (34); and/or

    the second motif layer (60), apart from the transparency regions (40) generated by the action of radiation, lies completely within the area of the contrast sublayer (34).
11. Security element (12) according to at least one of Claims 1 to 10, characterized in that one or more transparent layers are arranged on the side of the radiation-sensitive motif layer (30) facing away from the lens grid (24), such that an underlying surface situated beneath the security element (12) is visible as a second appearance when the security element (12) is viewed from a second viewing direction through the lens grid (24) and the transparency regions (40) of the radiation-sensitive motif layer (30).
12. Data carrier comprising a security element (12) according to at least one of Claims 1 to 11; in particular
    comprising a security element (12) embodied according to Claim 11, characterized in that the data carrier is provided, in a subregion, with a second motif layer (60) structured in the form of a second motif, and in that the security element (12) is arranged with the lens grid (24) and the transparency regions over the second motif layer (60), such that the second motif is visible as a second appearance when the security element (12) is viewed from a second viewing direction through the lens grid (24) and the transparency regions (40) of the radiation-sensitive motif layer (30).
13. Method for producing a security element (12) comprising a lens grid image, in which method

    - provision is made of a carrier substrate and the latter is provided with a lens grid (24) composed of a plurality of microlenses (26), and with a radiation-sensitive motif layer (30) arranged at a distance from the lens grid (24),

    - in the radiation-sensitive motif layer (30), a multiplicity of transparency regions (40) are generated by the action of radiation through the lens grid (24), and

    - the radiation-sensitive motif layer (30) is embodied, at least in the motif region, with a colour sublayer (32) and a contrast sublayer (34),
    characterized in that

    - the colour sublayer (32) comprises colour-imparting effect pigments which appear coloured against the background of the contrast sublayer (34) and which appear transparent without a contrast layer.
14. Method according to Claim 13, characterized in that the lens grid image shows at least two different appearances from different viewing directions, and in that in the method

    - the transparency regions (40) in the radiation-sensitive motif layer (30) are generated with register accuracy with respect to the microlenses (26) of the lens grid, and

    - the radiation-sensitive motif layer (30) is embodied in opaque fashion outside the transparency regions (40) generated by the action of radiation and in structured fashion in the form of a first motif, such that the first motif is visible as a first appearance when the security element (12) is viewed from a first viewing direction through the lens grid (24).
15. Method according to Claim 13 or 14, characterized in that the radiation-sensitive motif layer (30) is exposed to laser radiation through the lens grid (24) in order to generate the transparency regions (40).

Images