Security element with combination security feature

Abstract

The invention relates to a security element for safeguarding security papers, value documents, and other data carriers using a combination security feature (16) which contains a colored image motif, wherein - the combination security feature (16) displays a first image motif with a 2D or 3D appearance under normal illumination using visible light (20) and - under hybrid illumination using visible light (20) and UV light (22), displays a second image motif with a 3D appearance. The combination security feature (16) has a body color layer (32, 34) with at least one visually visible body color in order to produce the first image motif and at least one luminescent color layer (36) arranged above and / or below the body color layer (32, 34), said luminescent color layer, together with the body color layer (32, 34), producing the second image motif upon being excited with UV light.

Description

[0001] Security element with combination security feature

[0002] The invention relates to a security element for securing security papers, value documents and other data carriers with a combination security feature, a method for producing such a security element and a value document or security document with such a security element.

[0003] Data storage devices, such as valuables or identification documents, as well as other valuable items such as branded goods, are often provided with security features for security purposes. These allow the authenticity of the data storage devices to be verified and also serve as protection against unauthorized reproduction. In this context, luminescent substances are known to be used to protect valuables or identification documents. The presence of the luminescent substances can then be verified using a UV lamp, for example.

[0004] For example, from document EP 1 567358 B2, security prints with several areas are known which show the same color impression under white light, for example daylight, but which show different color impressions in luminescence upon additional UV excitation.

[0005] Furthermore, it is known that the color impressions of luminescent printing inks generally change due to aging and environmental factors, and that both the intensities and color impressions of different luminescences can change at different rates. Therefore, with conventional luminescent features of security elements, many motifs that are easily recognized by a viewer due to their color impression or multi-color combination cannot be reproduced due to the lack of color stability.

[0006] Based on this, the object of the invention is to overcome the disadvantages of the prior art and, in particular, to provide a data carrier with a luminescent security element with a high level of forgery security and an attractive visual appearance.

[0007] Summary of the invention:

[0008] 1. (First aspect of the invention): Security element for securing security papers, value documents and other data carriers with a combination security feature which contains at least one coloured image motif, wherein the combination security feature shows a first image motif with a 2D or 3D appearance under normal illumination with visible light, and shows a second image motif with a 3D appearance under hybrid illumination with visible light and UV light, wherein the combination security feature has a body colour layer with at least one visually visible body colour for generating the first image motif and has at least one luminescent colour layer arranged above and / or below the body colour layer, which, when excited with UV light, generates the second image motif together with the body colour layer.

[0009] For the purposes of this description, normal lighting refers to visible light in the spectral range from 380 nm to 780 nm, especially natural or artificial daylight and room lighting. UV light refers to light in the wavelength range from 200 nm to 380 nm, especially light with emission peak wavelengths at 254 nm or 365 nm.

[0010] The combination security feature can also be visible under pure UV illumination without normal lighting, whereby a change from normal lighting to UV illumination results in a change in information, whereby a 3D appearance can be visible even under pure UV illumination.

[0011] Instead of 3D appearances, the combination security feature can also show a pseudo-3D effect.

[0012] 2. (Preferred embodiment): Security element according to paragraph 1, characterized in that the first image motif shows a 2D appearance, and the second image motif shows a 3D appearance which represents a spatial extension of the first image motif.

[0013] For example, a flat triangle (2D appearance) becomes a prism or a tetrahedron (3D appearance), or a square (2D appearance) becomes a pyramid or a truncated pyramid (3D appearance). Further advantageous examples are listed below.

[0014] 3. (Preferred embodiment): Security element according to paragraph 1, characterized in that the first image motif shows a 3D appearance, and the second image motif shows a 3D appearance that represents a spatial variation of the first image motif.

[0015] For example, a spatial object is presented with a change in perspective (viewing from the left or right), a change in lighting (light from the front or back), or a change in contrast (low vs. high) or color appearance (grayscale vs. color). Further advantageous examples are listed below.

[0016] 4. (Preferred embodiment): Security element according to at least one of paragraphs 1 to 3, characterized in that the luminescent color layer emits white luminescent light upon UV excitation and / or that the luminescent color layer emits different luminescent colors in certain regions upon UV excitation.

[0017] 5. (Preferred embodiment): Security element according to at least one of paragraphs 1 to 4, characterized in that the luminescent color layer is transparent or translucent in the visible spectral range, in particular that the luminescent color layer is not visually perceptible under normal lighting without UV component.

[0018] 6. (Preferred embodiment): Security element according to at least one of paragraphs 1 to 5, characterized in that the luminescent color layer contains a mixture of red, green and blue emitting luminescent pigments which have high light and environmental resistance due to a uniform coating material.

[0019] High environmental resistance means, in particular, good performance in banknote tests known to those skilled in the art, especially in physical tests (temperature exposure) and chemical tests (resistance to acids, detergents, soap solutions, solvents, and the like). 7. (Preferred embodiment): Security element according to at least one of paragraphs 1 to 6, characterized in that the luminescent color layer, upon UV excitation, produces a brightness modulation of the 2D appearance of the first image motif, in which elements closer to the observer shine brighter and elements further away shine dimmer.

[0020] 8. (Second aspect of the invention): Method for producing a security element according to one of paragraphs 1 to 7, in which a body colour layer with at least one visually visible body colour is applied to a substrate to produce the first image motif, and at least one luminescent colour layer is applied above and / or below the body colour layer, which, when excited with UV light, together with the body colour layer produces the second image motif.

[0021] 9. (Preferred embodiment): Method according to paragraph 8, characterized in that the body colors are applied with a number of printing plates of a printing press, and a white emitting luminescent ink layer is applied with a single further printing plate of the printing press, or that a colored emitting luminescent ink layer is applied with several, in particular two or three further printing plates of the printing press.

[0022] Alternatively, the body color layer and the luminescent color layer can be first created on separate substrates and then laminated onto each other. This is particularly suitable for the production of passports or cards.

[0023] In these designs, the luminescent ink of the luminescent ink layer is advantageously applied with locally varying areal densities to create brightness modulation. A varying areal density can be achieved, for example, by varying the number of lines, line width, line spacing, screen ruling, or dot size.

[0024] 10. (Third aspect of the invention): A valuable document or security document with a security element according to any one of paragraphs 1 to 7.

[0025] The value document can, in particular, be a banknote, a certificate, a voucher, a check, a high-value admission ticket, a tax stamp, high-value product packaging, or a brand protection item. The security document can, in particular, be an identification card, such as an ID card, a data page for an ID document, a bank card, a credit card, a passport, or a driver's license.

[0026] For the luminescent color layer, the present invention advantageously uses coordinated luminescent pigments that have a uniform shell material for the emission colors red, green, and blue, thus offering essentially the same printability. Due to the uniform shell material, the pigments also exhibit virtually identical stability and aging properties. Therefore, even if the emission intensity of the pigments decreases over time, the reduction occurs concurrently for the different colored pigments, so that the overall color impression of the mixed colors produced by the pigments, in particular the mixed color white, remains virtually unchanged. The low emission intensity can be compensated, for example, by a higher intensity of the UV excitation radiation.Preferably, one of the following printing processes is used within the scope of the invention: i) Background printing (offset / nyloprint) is used with particular advantage, optimally registered by printing in a super-simultaneous printing press with multiple printing units; ii) alternatively, inkjet processes, screen printing, and intaglio printing can be used. Advantages of the inkjet process include the possibility of customization in the card and ID area, as well as increased protection against tampering through the use of different layers in a multi-layer system. In intaglio printing, luminescence brightness modulations can be implemented spatially resolved through the engraving depth in the intaglio printing plate.

[0027] The following structures are particularly suitable for the layer sequence of the combination security feature: a) Background body colours in combination with visually transparent white emission ink when excited by UV light b) Background body colours in combination with special light-stable fluorescent inks made from different mixtures of red, green or blue emission ink, printed on top of each other / below each other / next to each other / into each other or mixed into each other c) as in b), whereby at least one of the RGB fluorescent base colours is replaced by a phosphorescent ink (maximum white phosphorescence), and d) one of the UV-luminescent inks can be a bifluorescent dye, i.e. it can show a different emission colour at different excitation wavelengths (e.g. 254 nm or 365 nm). The fluorescent and / or phosphorescent inks can be excited in different wavelength ranges, in particular in UV-A, UV-B or UV-C. The security element orThe combination security feature can be applied to a security substrate, e.g. banknote substrate (cotton, hybrid, window, polymer) or incorporated into a card body (ID card, ID documents) as a multi-layer laminate.

[0028] By adding a fluorine dye in a first color tone, a high-contrast image can be created on a body color of a different color tone under UV excitation.

[0029] The first and / or second image motif is particularly in the form of ornaments in the form of rosettes, strips, or bands within a banknote, for example, as meanders or recurring fragments of a symbol, or represents a simply abstracted object created as a 2D object or as a 3D object with a shallow depth effect, such as a coat of arms, seal, value number, the front view of a building, a structure, the side view of an animal, or a portrait of a person. In the latter case, a strong 3D effect of the portrait is created by line reproduction under daylight, particularly with intaglio printing.

[0030] The advantages of the designs according to the invention include: a change in information from 2D to 3D or a change in information from 3D to 3D variation (for example, changed perspective, depth effect, or plasticity), new attractive and chemically / physically stable designs with any fluorescent color and spatial 3D perspective under UV light that is not visible under daylight, an increase in the counterfeiting hurdle, an improvement in machine authenticity detection, and an upgrade of previous banknote designs and identity document designs.

[0031] Further embodiments and advantages of the invention are explained below with reference to the figures, in which a true-to-scale and true-to-proportion reproduction has been omitted in order to increase clarity.

[0032] They show:

[0033] Fig. 1 in (a) a schematic representation of an identification card with a security element according to the invention with a combination security feature and in (b) and (c) the appearance of the security element under normal lighting and hybrid lighting, respectively,

[0034] Fig. 2 and 3 illustrate the principle of producing security elements according to the invention, and

[0035] Fig. 4 and 5 show security elements with combination security features according to further embodiments of the invention.

[0036] The invention will now be explained using the example of securing identification cards. Figure 1 shows a schematic representation of an identification card 10, such as an ID card, bank card, credit card, or driver's license, in Fig. 1(a). In addition to conventional markings, such as a serial number 12 or a portrait 14 of the cardholder, the identification card 10 also has a combination security feature 16 according to the invention with a colored image motif to ensure authenticity.

[0037] Under normal illumination with visible light 20, the combination security feature 16 displays a first, purely two-dimensional image motif, which, with a uniform color, depicts a geometric pattern composed of several filled parallelograms. The first 2D image motif of the combination security feature 16 is shown in more detail in Fig. 1(b).

[0038] The appearance of the combination security feature 16 changes significantly when exposed to UV light 22 in addition to daylight 20. As shown in Fig. 1(c), the combination security feature 16 displays a second, now three-dimensional image motif under hybrid illumination with visible light 20 and UV light 22, representing an arrangement of five cubes arranged in the shape of the letter "X" when viewed obliquely from above. Under hybrid illumination, the cubes of the second image motif can glow with a uniform color or in several different colors, as shown in Fig. 1(c).

[0039] The differing, yet interrelated, appearances under normal lighting (daylight) and hybrid lighting (daylight + UV light) create a surprising effect for the viewer, offering high reassurance and recognition value. An image motif that appears two-dimensional under daylight becomes, with additional UV stimulation, a three-dimensional image with a spatial perspective, representing a spatial extension of the 2D motif. Figures 2 and 3 illustrate the principle of creating such a

[0040] Combination security feature 16.

[0041] First, Fig. 2(a) shows the provision of a two-dimensional first image motif 30 in body color, for example with red motif areas 32 and blue motif areas 34. Figure 2(a) also shows the 2-D visual appearance of the combination security feature under normal illumination with visible light. Fig. 2(b) shows a luminescent color layer 36 of the luminescent color white designed according to the invention for generating a three-dimensional (3D) effect, and Fig. 2(c) shows the appearance 38 of the combination security feature under hybrid illumination, i.e. with additional UV excitation, for example at 254 nm or 365 nm.

[0042] Figure 3 shows schematically the layer structure of a security element according to the invention in cross section, wherein Fig. 3(a) shows a currently preferred structure and Fig. 3(b) shows a likewise advantageous, alternative structure.

[0043] With reference to Fig. 3(a), in a first step, the first image motif 30 is printed in one or more visually visible body colors 32, 34 onto a substrate 35. Subsequently, in a second step, a luminescent ink layer 36 is printed, which is visually transparent or translucent and fluoresces with the emission color white upon UV excitation. The white fluorescent ink is composed of a mixture of red, green, and blue fluorescent pigments, in particular red, green, and blue fluorescent pigments, which exhibit high light and environmental stability due to a uniform coating material. As shown in Fig. 3(b), the luminescent ink 36 can be printed not only above but also below the body color 32, 34. However, due to the lower ink consumption, printing above the body color is currently preferred.In all variants, the print motif is advantageously applied using a printing plate in Nyloprint or wet offset printing, or alternatively using screen printing (water-based or UV-curing).

[0044] The design and production of the luminescent color layer 36 can be carried out as follows, for example: To influence the 3D depth effect of the first image motif, a 3D illustration program or CAD software is used, for example, although such effects can also be implemented using standard image editing programs. Ideally, to create a 3D object, work is carried out in an image editing program for 3D effects and various settings are optimized for graphic output. Possible settings include the size and shape of the object, perspective rotation (x, y, z), as well as distortion in the x, y, z directions, viewer (position, perspective), lighting (direction, size, intensity, lighting source, lighting color, lighting angle, number of light sources), reflections on the surface of the object, transparency of the object ratio, strength of the depth effect.

[0045] A corresponding grayscale image is then rendered for a luminescent color, such as white fluorescence. To create a strong sense of depth in a 3D object, the entire brightness range of 0-255 grayscale values ​​should be used for a single object. The depth effect is extracted from the 3D object image as a grayscale channel and then transformed into printable data, for example, using halftone / raster / area / dot, or line modulation.

[0046] As illustrated in Figures 1 and 2, in a first variant of the invention, the first image motif shows a 2D appearance, while the second image motif shows a 3D appearance, which represents a spatial extension of the first image motif.

[0047] With the help of a fluorescent ink, a 2D object can be given the effect of depth, making it appear three-dimensional under UV illumination with a wavelength of 254 nm or 365 nm. For example, a flat triangle becomes a prism or a tetrahedron, or a square becomes a pyramid / truncated pyramid. An irregular hexagon or parallelogram, for example, becomes a cuboid. The outer contour of the 2D object advantageously determines the outer contour of the 3D object, but can also deviate from it. When using white-luminous fluorescence, the body color of the 2D object primarily determines the color of the 3D object. Initially, fluorescence only creates the 3D effect, or depth effect. Super-simultaneous printing ensures precise printing of at least one or more different body colors and at least one fluorescent color, preferably white fluorescence.Particularly preferred is the luminosity of the fluorescent colors and the absorption properties of the body colors.

[0048] If several objects are positioned in perspective relative to each other, the object closest to the light source is advantageously used with the highest luminosity, while objects further away appear darker. For example, the area coverage for a portion of the image that appears more distant is between 0-30%, for a medium-distance area between 25-70%, and for an area very close to the viewer between 70-100%.

[0049] It is particularly advantageous if the entire body color is visible under UV exposure. This can be achieved by coating the darker-looking areas of the surface with less fluorescent color, i.e., by covering only a smaller area, while areas that are perspectively facing the viewer exhibit significantly higher proportions of fluorescent color.

[0050] In an advantageous embodiment, a low area coverage of 1-15% of fluorescent ink is printed in areas where image information is perspectively distant from the viewer, and a high area coverage of, for example, 60-100% of fluorescent ink is printed in areas that are perspectively close to the viewer. It is particularly advantageous if the fluorescence luminosity differs sufficiently between the distant and the nearby areas, and the fluorescence luminosity gradually increases or decreases.

[0051] In a further development of the invention, the fluorescent ink used additionally introduces a color appearance that deviates from the body color of the 2D effect, for example by using a colored fluorescent ink in a single printing plate, either as a single fluorescent ink or as a fluorescent ink mixture. The combination of several different fluorescent ink printing plates is also possible. For example, instead of a white fluorescent ink, this development uses the underlying fluorine base colors for the 3D depth effect. This makes it possible to divide the spatial depth between preferably 3-4 printing plates (for example, one each for red, green, blue, and possibly one for another fluorescent special color). One advantage of this development is that even locally limited 3D color effects can be created in an object or partial object area.However, this advantage requires more effort, since at least two or more printing plates must be used instead of an additional "fluoroadded printing plate".

[0052] In a further advantageous embodiment, the different color tone appearance is achieved by using more than one printing plate and dividing it into at least 2, ideally 3 basic fluorescent colors (e.g. red, green, blue), the weighted proportion of which results in white fluorescence. For example, in the aforementioned tetrahedron, each individual triangular surface can be given a different color, yet still achieve a common 3D depth effect (defined by the intensity curve of the luminescence). The modulation of the individual printing plates differs in their modulation of the individual RGB channels, for example, a first triangular surface is yellow (modulation of red and green fluorescence from 0-100% each), a second triangular surface is red (modulation from 0-100% red), and a third triangular surface is green (modulation from 0-100%).When combining individual triangular objects, a different coloration of the individual tetrahedrons displayed under UV with the same spatial perspective is also possible. Overprinting several fluorescent colors can occur as a solid surface or only partially in rasterized areas. The rasters can be designed with different angular orientations or even nested within one another. For example, in the design of Figures 2 and 3, the partial areas of the luminescent color layer 36 lying above the partial areas 32 can emit a different luminescent color than the partial areas lying above the partial areas 34. In this case, the body color areas 32, 34 can also have the same body color; the different color then surprisingly only becomes apparent upon UV excitation.

[0053] Another example is the design of the combination security feature 16 in Fig. 1. In this embodiment, the body-color background print appears as a nested surface under normal lighting (daylight), visually representing a polygon. Hybrid illumination with UV light reveals a perspective representation of cubes on the same base area. Only one UV plate, for example, for white fluorescence, is required to create a 3D appearance with perspective.

[0054] In a variant with UV separation by coating with different fluorescent colors, each fluorescent color requires its own printing plate, which already contains different 3D perspective information. In this case, each individual cube of a specific fluorescent color can contain three different areas. These three areas are provided, for example, with 100% area coverage for the front side, a gradient with 70-20% area coverage for the top side, and a gradient with 50-5% area coverage for the right side of the respective fluorescent color. This creates the impression that the light source is illuminating the cube arrangement from the front and above, from the viewer's perspective, and illuminating the cubes primarily on the front side (Fig. 1(c)).It is also possible, for example, for the front, top, and right sides of all cubes to display the same fluorescent color, but for the colors of the front, top, and right sides to differ. In this variant, brightness gradients can also be implemented.

[0055] Using "brightness grayscale gradients" displayed in fluorescence, not only the perspective 3D shape of an object but also the depth of its surroundings or objects in relation to one another can be created. The first image motif can therefore contain multiple objects, with objects that should appear further away being given a lower luminescence intensity, while objects that should appear in the foreground are illuminated accordingly brighter. This creates a strong dynamic perspective through UV fluorescence, even without the usual color information. If such a fluorescence image is combined with a body-color original image using hybrid illumination, a significantly stronger sense of depth is created than can be achieved with a normal CMYK print.

[0056] The change from a 2D to a 3D appearance is not limited to the area of ​​the 2D motif. Figure 4 illustrates a combination security feature 40 with a supplementary motif. Fig. 4(a) shows the appearance of the security feature under normal lighting. The body color area 42, for example, is formed in the shape of an oval with the digit sequence "100" cut out of black body color.

[0057] The body-color oval 42 of Fig. 4(a) is supplemented by a fluorescent color region 44 with blue emission to form a full-circle disk, as shown in Fig. 4(b). Additionally, the full circle is overprinted with a fluorescent color region 46 with white fluorescence, as shown in Fig. 4(c), which, through a brightness distribution, gives the full circle the spatial appearance of a sphere. The fluorescent color regions 44, 46 are not visible under normal illumination. Under hybrid illumination, the interaction of the body color and the fluorescent colors results in the appearance of Fig. 4(d), which shows the observer the spatial image of a sphere with lateral, blue color regions 44 and a central blue-black color region 42 with the number sequence "100."As explained above, the spatial appearance results in particular from the varying brightness of the white fluorescence in certain areas, which is higher in parts of the sphere closer to the observer and lower in areas further away from the observer.

[0058] In a further variant of the invention, which is now illustrated with reference to Fig. 5, the first image motif already shows a 3D appearance, wherein the second image motif shows a 3D appearance that represents a spatial variation of the first image motif.

[0059] Figure 5 shows a security element with a combination security feature 50 in the form of a horizontal prism. Figure 5(a) shows the appearance of the security feature under normal lighting. The two solid-color areas 52, 54 are each printed with black solid ink, with the solid-color area 54 being printed with a high area coverage and the solid-color area 54 with a low area coverage. Due to the different brightnesses of the two solid-color areas 52, 54, the security feature appears as a horizontal prism with a 3D impression, with the incident light appearing to come from the rear top right.

[0060] Figure 5(b) shows the appearance of the security feature under hybrid illumination with daylight and UV light. As can now be seen, the color areas 52 and 56 are overprinted with blue fluorescent ink, while there is no fluorescent ink in the color area 54. In the color area 52, the fluorescence is partially absorbed by the black body color, so that this area luminesces less than the color area 56. The color area 54 does not luminesce in UV light; it is barely visible in moderate daylight or in dim conditions. Due to the different brightnesses of the two color areas 52, 56 in luminescence, the security feature still appears as a horizontal prism with a 3D impression, but with a change in perspective – the viewing position appears to change from a viewing position obliquely from the right (Fig. 5(a)) to a viewing position obliquely from the left (Fig. 5(b)).

[0061] Figure 5(c) shows another change in the 3D appearance: based on the design of Figure 5(a), the color regions 52 and 54 are covered with fluorescent ink, with high coverage for color region 52 and low coverage for color region 54. Accordingly, under hybrid illumination, the front surface of the prism now shines brighter than the side surface, and the incident light now appears to come from the front.

[0062] The described spatial variation of a 3D appearance can be used particularly advantageously in portraits. For example, a true-color portrait made of body colors can be given a particularly strong three-dimensional impression by applying a white luminescent layer that glows more or less intensely in certain areas. In another variant, the first image motif shows a 3D grayscale image, for example, a grayscale portrait, and the luminescent layer contains the corresponding 3D color image. Switching from normal to hybrid lighting transforms the grayscale portrait into a color portrait of the person depicted.

Claims

Patent claims 1. Security element for securing security papers, value documents and other data carriers with a combination security feature which contains at least one coloured image motif, wherein the combination security feature shows a first image motif with a 2D or 3D appearance under normal illumination with visible light, and shows a second image motif with a 3D appearance under hybrid illumination with visible light and UV light, wherein the combination security feature has a body colour layer with at least one visually visible body colour for generating the first image motif and has at least one luminescent colour layer arranged above and / or below the body colour layer, which, when excited with UV light, generates the second image motif together with the body colour layer.

2. Security element according to claim 1, characterized in that the first image motif shows a 2D appearance, and the second image motif shows a 3D appearance which represents a spatial extension of the first image motif.

3. Security element according to claim 1, characterized in that the first image motif shows a 3D appearance, and the second image motif shows a 3D appearance which represents a spatial variation of the first image motif.

4. Security element according to at least one of claims 1 to 3, characterized in that the luminescent color layer emits white luminescent light upon UV excitation and / or that the luminescent color layer emits different luminescent colors in certain regions upon UV excitation.

5. Security element according to at least one of claims 1 to 4, characterized in that the luminescent color layer is transparent or translucent in the visible spectral range, in particular that the luminescent color layer is not visually perceptible under normal lighting without UV component.

6. Security element according to at least one of claims 1 to 5, characterized in that the luminescent color layer contains a mixture of red, green and blue emitting luminescent pigments which have high light and environmental resistance due to a uniform coating material.

7. Security element according to at least one of claims 1 to 6, characterized in that the luminescent color layer, upon UV excitation, produces a brightness modulation of the 2D appearance of the first image motif, in which elements closer to the observer shine brighter and elements further away shine weaker.

8. A method for producing a security element according to one of claims 1 to 7, in which a body colour layer with at least one visually visible body colour is applied to a substrate to produce the first image motif, and At least one luminescent ink layer is applied above and / or below the body-color layer, which, when excited with UV light, together with the body-color layer, creates the second image motif.

9. The method according to claim 8, characterized in that the body colors are applied using a number of printing plates of a printing press, and a white-emitting luminescent ink layer is applied using a single additional printing plate of the printing press, or that a colored-emitting luminescent ink layer is applied using several, in particular two or three, additional printing plates of the printing press.

10. A value document or security document with a security element according to one of claims 1 to 7.

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