EP3452299B1 - Security element having a luminescent print - Google Patents

Description

The invention relates to a security element for securing security papers, documents of value and other data carriers, with a luminescent print which shows a multicolored motif in UV light. The invention also relates to a method for producing such a security element and to a data carrier equipped with such a security element.

Data carriers, such as value or identity documents, but also 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. In this context, it is known to print fluorescent colors on a security paper using various printing processes. For example, a fluorescent color is printed on in the form of a motif which cannot be seen in normal daylight, but becomes visible when viewed under UV lighting. The fluorescent color can also be mixed with a color that is visible in daylight, so that the printed motif is also visible in daylight, albeit with a different color tone.

In the passport sector, the printing of true-color luminescent images has also been known for several years. The implementation usually takes place in ink-jet printing with special colors that are not visible in visible light and, when stimulated by UV light, show a color impression comparable to a classic picture, for example a portrait of the passport holder. JP 2000 158823 A is an example of printing true-color luminescent images and suggests using different pigments that are white in visible light and that luminesce in the colors red, green and blue in UV light.

Luminescent substances are also used as machine, preferably spectrally, detectable authenticity features. WO 2008/004015 A2 concerns a New Anti-Stokes material with an individual, spectrally detectable, white emission spectrum as an authenticity feature, which can optionally also be used together with monochrome authenticity features. WO 2008/004015 A2 shows the preamble of claim 1.

On this basis, the invention is based on the object of specifying a security element of the type mentioned at the beginning with an appealing visual appearance and a high level of protection against forgery.

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

• der lumineszierende Aufdruck durch gedrucktes Lumineszenzweiß einerseits und zumindest zwei gedruckte Lumineszenz-Grundfarbstoffe, beispielsweise aus der Gruppe bestehend aus Lumineszenzgrün, Lumineszenzrot und Lumineszenzblau, andererseits gebildet ist, und
• das mehrfarbige Motiv auch in farbigen Bereichen unbunte Anteile enthält, die im Aufdruck zumindest teilweise durch Lumineszenzweiß gebildet sind.

According to the invention it is provided in a generic security element that

• the luminescent imprint is formed by printed luminescent white on the one hand and at least two printed luminescent basic dyes, for example from the group consisting of luminescent green, luminescent red and luminescent blue, on the other hand, and
• the multicolored motif also contains achromatic components in colored areas which are at least partially formed by luminescent white in the print.

In the context of this description, the term luminescent white denotes a white luminescent luminescent substance. Analogously, the terms luminescent red, luminescent green and luminescent blue denote red, green and blue luminescent luminescent substances, respectively. At least two, but usually three, luminescent basic dyes are used. Luminescent red, luminescent green and luminescent blue form the usual basic colors. Choosing other basic colors for the luminescent basic dyes is possible in the present case. Three basic luminescent dyes can be chosen so that their additive color mixture results in white.

The luminescence is preferably a photoluminescence. Luminescence includes fluorescence and phosphorescence, in particular also anti-Stokes luminescence. Suitable luminescent substances are, for example, all fluorescent and phosphorescent substances. Substances that emit white light after appropriate excitation are particularly suitable as luminescent white. Luminescent white can also be provided (before printing) as a mixture of luminescent pigments, in particular luminescent red, blue and green. The energy transfer from excitation to luminescence can also be multi-stage, so that a first substance absorbs the excitation energy and transfers it directly or via further intermediate steps to the finally emitting luminescence substance. In the present case, luminescent colors that are as transparent as possible are used, which can be achieved, for example, through the use of small luminescent pigments, in particular nanopigments, and / or the use of a highly transparent binder.

The excitation of the luminescent substance or, in the case of a transfer of the excitation energy, the excitation of the first substance takes place preferably in the ultraviolet (UV) spectral range. An excitation in the infrared range for the luminescence in the visible range is also conceivable. The wavelength range from 315 nm to 380 nm is used as long-wave UV radiation (UV-A), the wavelength range from 280 nm to 315 nm as medium-wave UV radiation (UV-B) and the wavelength range from 100 nm to 280 nm as short-wave UV Radiation (UV-C). The excitation can take place with UV-A and / or UV-B and / or UV-C radiation.

The multi-colored motif contains not only the basic colors, such as red, green, and blue, but also mixed colors of two or all three basic colors. The motif therefore has a realistic appearance and is sometimes also referred to as a real color image or real color luminescence image in the context of this description.

It goes without saying that the multicolored motif can also contain pure gray levels without a color component in partial areas. In addition, however, the multicolored motif also contains achromatic components in the colored areas, which are described below with reference to Fig. 2 as explained in more detail by breaking down the color structure into an achromatic component and a chromatic component. According to the invention, these achromatic components of the color structure are now at least partially formed by luminescent white in the imprint.

By using luminescent white according to the invention, the process stability when printing true-color luminescent images can be significantly increased. For example, some printing processes, such as offset or letterpress printing, can have procedural problems with printing three basic colors on top of one another. By using luminescent white, the number of basic colors required can generally be reduced to two, as explained in more detail below.

Any problems with the drying of the inks on one of the substrates, in particular the physical drying of mineral oil-based offset inks, can also be overcome, since the overall ink coverage can be reduced by using luminescent white. Finally, problems with the controlled splitting-back of color when inking a printing plate cylinder, a transfer cylinder, for example a blanket cylinder in offset printing, and the substrate, since the color splitting takes place all the more undefined, the greater the number of different layers of ink that have not been dried between them.

The inventors have also found that the use of luminescent white in addition to the luminescent basic dyes in the print also increases the color space that can be displayed. The use of fluorescent white also enables increased flexibility in the selection of the luminescent basic dyes. In particular, when selecting the luminescent basic dyes, fewer compromises have to be made in terms of stability, luminosity and / or price than when a true color luminescent image is printed exclusively with the three luminescent basic dyes. In addition, color fluctuations are less noticeable when using fluorescent white than in the case that a white color impression has to be generated by printing the three luminescent basic colors one above the other or next to one another. In the latter case, not only does the intensity of the degree of whiteness change, but a certain bluish, yellowish or reddish color can also arise.

In a preferred embodiment, the luminescent print is formed by luminescent white on the one hand and the three luminescent basic dyes luminescent green, luminescent red and luminescent blue on the other.

The achromatic components of the multicolored motif are preferably formed entirely by the luminescent white at least in a partial area of the motif. In this case, for each color pixel or for each one of the same color Color range can be dispensed with at least one of the luminescent basic dyes used.

The luminescent white can consist of a single luminescent substance, but can also be formed from a mixture of two or more luminescent substances, which in combination result in a white. The mixture can contain both dyes and pigments. In order to avoid segregation in the color in the case of a luminescent white, the luminescent substances forming the luminescent white advantageously have a similar surface functionalization due to a surface coating. Alternatively, a segregation of the color can also be counteracted in that the luminescent substances forming the luminescent white are present in a common capsule.

The fluorescent white can in particular have a high luminosity which exceeds the luminosity of a combination of the three luminescent basic dyes.

In an advantageous development, the luminescence white of the luminescent print can be excited in a first UV excitation area together with the luminescent basic dyes present in the print. In a second UV excitation area, on the other hand, the luminescent white can be excited individually without the luminescent basic dyes present in the print. The first UV excitation area can be, for example, the long-wave UV, and the second UV excitation area can be the short-wave UV.

In this way it can advantageously be achieved that the luminescent print shows the multicolored motif when excited in the first UV excitation area, while it shows the multicolored motif when excited in the second UV excitation area shows a grayscale reduction of the multicolored motif, i.e. a grayscale motif that has the same image content as the multicolored motif and is simply not colored.

The luminescent white of the print has a double function in this development, since on the one hand it is part of a first security feature in the form of the colored luminescent motif. On the other hand, the luminescent white is also part of a separately testable second security feature which is given in the form of a gray-scale image through the spatial distribution of luminescent white in the print. The grayscale image can in particular represent a grayscale reduction of the multicolored motif, but it can also contain additional, in particular hidden, information through a spatial variation of the luminescence white component, as explained in more detail below.

In order not to allow excitation in the second UV excitation area, the luminescent basic dyes can contain, for example, an absorber for the second UV excitation area, so that excitation with UV radiation from the second UV excitation area does not lead to luminescence of the luminescent basic dyes.

Another development of the invention provides that the achromatic portions of the motif in a camouflaged area of the motif are formed only by the luminescent basic dyes. In this way it can advantageously be achieved that the camouflaged area cannot be recognized when excited in the first UV excitation area, while it becomes visible when excited in the second UV excitation area.

In an advantageous embodiment of the invention, the luminescent print in UV light shows, in addition to the multicolored motif, a grayscale pattern with different brightness values, which is formed by the luminescent white without using the luminescent basic dyes. Such a grayscale pattern can practically not be produced with luminescent basic dyes without a remaining residual color, so that an adjustment of the security element without the use of luminescent white can also be easily recognized by the layperson.

In order to obtain a large number of brightness levels in the pure gray scale pattern, this can for example contain a gray wedge or even consist of one. In a gray wedge, any residual color from an adjustment is particularly noticeable. The pure grayscale pattern can in particular also contain continuous gray transitions, since these are also particularly difficult to reproduce with the luminescent basic dyes alone.

In a further embodiment, a multi-colored motif is divided into a multi-colored sub-area and a monochromatic sub-area. The monochromatic sub-area is preferably only printed with luminescent white. The subregions are arranged with an exact fit to one another, especially since they are generated in one printing process. The multicolored sub-area is preferably arranged within the monochromatic sub-area. A multi-colored main motif, such as a building, a tree or a person, can thus be set off particularly clearly from the monochromatic or gray-scale background, such as a landscape, a building or a vehicle. In a further development of the embodiment, the entire motif can be excited with a first radiation (UV-A) and selectively only the multicolored partial area with one second radiation (UV-B). For this purpose, the basic dyes can only be excited by radiation from one of the UV ranges (UV-A, UV-B or UV-C) while the luminescent white can be excited by UV radiation from at least two (or all) of the UV ranges (UV -A, UV-B and UV-C).

In a further embodiment, the luminescent white or at least one of the luminescent basic dyes is phosphorescent. Afterglow after the end of the excitation can be seen. The afterglow would only be visible to an observer if phosphorescent agents with a longer afterglow time (> 1-2 seconds) were used. An afterglow, possibly also shorter, for example in the millisecond range, can be recognized or evaluated automatically as an authenticity feature.

In one embodiment, the luminescent white is printed with a different grid than the luminescent basic dyes. The screen can differ in predetermined screen parameters (in particular screen angle, screen dot shape or modulation) and / or in the screen type (e.g. frequency-modulated (1st order, 2nd order), amplitude-modulated or cross-modulated). The different grids can be used as an authenticity feature. Detection of the difference is possible, for example, by means of a microscope, raster counter (e.g. GHG mini-lithometer) and / or a moiré structure.

In an advantageous embodiment, the luminescent imprint is printed on a substrate that is essentially non-luminescent after UV excitation. In another, likewise advantageous embodiment, however, it is provided that the luminescent imprint is printed on a substrate that luminescent after UV excitation and is provided with a UV absorber in partial areas in order to locally reduce the substrate luminescence suppress. The UV absorber can absorb radiation from all UV ranges (UV-A, UV-B and UV-C) or selectively for radiation from one or two of the UV ranges.

• der lumineszierende Aufdruck durch Drucken von Lumineszenzweiß einerseits und durch Drucken von zumindest zwei Lumineszenz-Grundfarbstoffen, insbesondere aus der Gruppe bestehend aus Lumineszenzgrün, Lumineszenzrot und Lumineszenzblau, andererseits gebildet wird, und
• das mehrfarbige Motiv auch in farbigen Bereichen unbunte Anteile enthält, die im Aufdruck zumindest teilweise durch Lumineszenzweiß gebildet werden.

The invention also includes a method for producing a security element for securing security papers, documents of value and other data carriers, with a luminescent print that shows a multicolored motif in UV light, with the method

• the luminescent imprint is formed by printing luminescent white on the one hand and by printing at least two luminescent basic dyes, in particular from the group consisting of luminescent green, luminescent red and luminescent blue, on the other hand, and
• the multicolored motif also contains achromatic components in colored areas that are at least partially formed by luminescent white in the print.

The imprint can be produced by means of different printing processes, in particular gravure printing, ink-jet printing, flexographic printing, screen printing, offset printing or transfer printing (including sublimation transfer or thermal transfer).

Preferably, the imprint is rasterized. In particular, in order to display gray levels or different brightness values, the imprint is rasterized. Different brightness values are achieved by varying the area (in the grid) and / or varying the layer thickness. The imprint can be applied to a substrate in particular by gravure or offset printing. Transparent luminescent colors are preferably used. Transparent luminescent inks are particularly suitable for overprinting, in particular, two, three or four colors. This means that finer grid structures can be used, as possible deviations (register fluctuations) are less critical. Possible register fluctuations in the printing process from a first to the next printing unit would require a rather coarse grid structure with non-transparent colors. Point, chain or frequency-modulated grids can be used in particular as grids (for a grid). In the case of dot or chain screens, the screen angles of the individual colors are advantageously selected to be different from one another in order to avoid unsightly moiré structures.

As an alternative or in addition, the imprint can have a variable layer thickness in order to represent different brightness values, in particular by means of ink-jet printing or gravure printing. With ink-jet printing, it is possible to print several droplets on top of each other or to print droplets of different sizes. With gravure printing, it is possible to provide the printing plate with an engraving (created using a stylus or laser) which are of different depths. In both cases, different brightness values result from the transferred layer thickness.

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

in schematischer Darstellung eine Banknote mit einem erfindungsgemäßen Sicherheitselement,

Fig. 2

schematisch die Farbzusammensetzung eines Farbbereichs des mehrfarbigen Motivs, in (a) ohne die Verwendung von Lumineszenzweiß und in (b) unter Verwendung von Lumineszenzweiß,

Fig. 3

mehrere Farbpixel zur Erläuterung unterschiedlicher Varianten der Farbzusammensetzung,

Fig. 4

schematisch das Erscheinungsbild eines erfindungsgemäßen Sicherheitselements, in (a) bei Beleuchtung mit langwelliger UV-Strahlung und in (b) bei Beleuchtung mit kurzwelliger UV-Strahlung,

Fig. 5

in (a) eine erfindungsgemäße Aufteilung eines Aufdrucks in einen Tarnbereich und einen Normalbereich, in (b) schematisch das Erscheinungsbild des Aufdrucks bei Beleuchtung mit langwelliger UV-Strahlung und in (c) schematisch das Erscheinungsbild des Aufdrucks bei Beleuchtung mit kurzwelliger UV-Strahlung, und

Fig. 6

schematisch einen lumineszierenden Aufdruck eines weiteren erfindungsgemäßen Sicherheitselements.

Show it:

Fig. 1

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

Fig. 2

schematically the color composition of a color range of the multicolored motif, in (a) without the use of luminescent white and in (b) with the use of luminescent white,

Fig. 3

several color pixels to explain different variants of the color composition,

Fig. 4

schematically the appearance of a security element according to the invention, in (a) when illuminated with long-wave UV radiation and in (b) when illuminated with short-wave UV radiation,

Fig. 5

in (a) an inventive division of an imprint into a camouflaged area and a normal area, in (b) schematically the appearance of the imprint when illuminated with long-wave UV radiation and in (c) schematically the appearance of the imprint when illuminated with short-wave UV radiation, and

Fig. 6

schematically, a luminescent print of a further security element according to the invention.

The invention will now be explained using the example of security elements for bank notes. Figure 1 shows a schematic representation of a bank note 10 which is provided with a luminescent imprint 14 in a partial area with a security element 12 according to the invention. When viewed in UV light, the imprint shows a multicolored motif in an additive color mixture, here in the form of a butterfly for illustration. In the exemplary embodiment shown, the security element 12 is part of the bank note 10, but in other configurations it can also be designed as a separate security element, for example as a transfer element that is applied to a bank note or another data carrier.

A special feature of the luminescent imprint 14 is that the imprint is not only formed by the luminescent basic dyes luminescent green, luminescent red and luminescent blue, but that an achromatic portion of the colored motif is at least partially produced by luminescent white, i.e. a white luminescent luminescent substance.

For a more detailed explanation of the formation of the color mixture with the luminescent substances mentioned, FIG Fig. 2 (a) schematically the color composition of a certain color area of the multicolored motif, for example a color pixel or a monochrome area. For example, the color area shows a mixed color (real color), for example by luminescent red 20R, i.e. a red luminescent luminescent substance, with an area coverage of 100%, by luminescent green 20G, i.e. a green luminescent luminescent substance, with an area coverage of 75%, and by luminescent blue 20B , i.e. a blue luminescent luminescent substance, is formed with an area coverage of 40%.

Since the luminescent colors red, green and blue together produce a white or, more generally, an achromatic hue, the color structure of the Fig. 2 (a) be broken down into an achromatic component 22 and a chromatic component 24.

In the imprint 14, this achromatic component 22 is now, according to the invention, at least partially not formed by a combination of luminescent green 20G, luminescent red 20R and luminescent blue 20B, but rather by the additional luminescent substance luminescent white 20W, as in FIG Fig. 2 (b) shown. The amount of luminescent white 20W used allows the area coverage of the three luminescent basic dyes to be reduced (reference symbols 26R, 26G, 26B), so that overall a lower area coverage results.

The achromatic portion 22 of a color range can also be formed entirely by luminescent white 20W. In this case, at least one of the luminescent basic dyes used can be dispensed with. For example, in the embodiment of the Fig. 2 the area coverage of luminescence blue 20B can be reduced to zero by a sufficiently large proportion of luminescence white 20W and the true color of the color area can only be produced with luminescence green 20G, luminescence red 20R and luminescence white 20W.

The different variants are referring to Fig. 3 explained again on the basis of color pixels of a luminescent print. The color pixels can also represent a larger, single-colored surface area of the print. The sequence of layers or the arrangement of the color pixels can be generated in any order.

In the case of the color pixel 30 printed on a substrate 16, there are initially three luminescent colors 20R, 20G, 20B of luminescent green 20G, luminescent red 20R and luminescent blue 20B printed one on top of the other. The color pixel 30 has a structure accordingly Fig. 2 (a) without the use of luminescent white 20W. Such color pixels or color areas can be used in the present invention in particular to generate additional effects, such as those in connection with Fig. 5 more precisely described introduction of hidden information are used in a true color luminescence image.

The color pixel 32 luminesces in suitable UV light with the same true color as the color pixel 30 and has a structure Fig. 2 (b) on. In the case of the color pixel 32, part of the achromatic portion of the real color shown is replaced by luminescence white 20W, so that the area coverage of the luminescence basic colors 20R, 20G, 20B is correspondingly reduced.

Color pixel 34 also luminesces in suitable UV light with the same true color as color pixels 30 and 32. In color pixel 34, however, the achromatic portion of the true color is completely replaced by luminescent white 20W and the use of luminescent blue 20B can be dispensed with, since the desired true color can be produced with luminescence white 20W and the two luminescence basic dyes luminescence green 20G and luminescence red 20R alone.

The color pixel 36 is a modification of the color pixel 32 with all four luminescent colors 20W, 20R, 20G, 20B, the colors not being printed on top of one another but rather next to one another.

For example, a possible sequence of layers in which the luminescent white 20W is printed on the luminescent primary colors is not shown separately. Also not shown is the additional possibility of arranging at least one absorber layer between the luminescence layers of the color pixel 34. The absorber layer should preferably only cover a partial area, e.g. UV-A radiation, from which (UV) excitation radiation has an absorbing effect. The absorber layer can be printed over the entire area in the color pixel 34 on one of the luminescent layers or only partially cover one of the luminescent layers 20R, 20G, 20B or 20W.

Another special feature of the present invention is with reference to FIG Fig. 4 in that the luminescent substances 20W, 20R, 20G, 20B are selected so that the luminescent white 20W of the imprint 14 can be excited in the long-wave UV, for example at an excitation wavelength of 366 nm, together with the luminescent basic dyes 20R, 20G, 20B, while with an excitation in the short-wave UV, for example at an excitation wavelength of 254 nm, only the luminescence white 20W, but not the luminescence basic dyes 20R, 20G, 20B can be excited.

For illustration is in Fig. 4 assumed that the achromatic portions 22 of the butterfly motif in all colored areas are completely formed by luminescent white 20W. If the imprint 14 of the security element 12 is then exposed to long-wave UV radiation 42 from a UV lamp 40, all four luminescent colors 20W, 20R, 20G, 20B are excited and luminesce in the corresponding color white, red, green or blue. The imprint 14 thus shows the multicolored motif in real color representation 50 under long-wave UV radiation 42, as in FIG Fig. 4 (a) illustrated schematically. The luminescent white 20W can be arranged in the layer sequence above the basic dyes 20G, 20B, 20R, in particular if one of the or the basic dyes 20G, 20B, 20R include UV-absorbing components, for example UV-A absorbing. An optional background for the real-color representation 50 can be free of luminescent printing, but is preferably designed as a white (or light gray) luminescent background 51, for example printed with luminescent white 20W.

If, on the other hand, the imprint 14 is acted upon by a UV source 44 with short-wave UV radiation 46, only the luminescent white 20W is excited to luminescence, while the short-wave, non-excitable colored luminescent substances 20R, 20G, 20B do not shine. Since the luminescent white 20W in each case generates the achromatic portion 22 of the colored areas of the motif, the distribution of the white luminescent luminescent substance 20W corresponds to the brightness distribution of the respective color areas.

If only the luminescent white 20W lights up in the imprint 14, the imprint shows an achromatic motif, which represents a gray level reduction 52 of the multicolored butterfly motif. Since no colors can be represented in the illustrative figures, this effect is in Fig. 4 (b) by reducing the gray value image of the Fig. 4 (a) illustrated on a pure black and white image. If present, the optional background 51 will luminesce unchanged in white (or light gray).

The short-wave UV source 44 and the long-wave UV lamp 40 can be different devices, or they can also be integrated in one device and formed, for example, by a switchable lamp or a lamp with selectable (different) filter (s).

The different excitability of the luminescent substances 20W, 20R, 20G, 20B can be achieved, for example, in that for the luminescent white 20W a broadband excitable luminescent substance is selected, and for luminescent green 20G, luminescent red 20R and luminescent blue 20B each luminescent substances that can only be selectively excited in long-wave UV.

Alternatively, all of the luminescent substances used can in principle also be excitable over a broad band, with an additional UV absorber for the short-wave UV radiation being added to the luminescent basic dyes 20R, 20G, 20B so that incident short-wave UV radiation is absorbed and not causing luminescence Luminescent basic dyes 20R, 20G, 20B leads. Examples of such UV absorbers are Tinuvin 400 or resins or binders that absorb short-wave UV radiation. A typical broadly UV-stimulable luminescent substance is about CD 350 from Honeywell.

In a further training course of the bei Fig. 4 described principle, additional hidden information can be coded in a multicolored motif by a clever choice of the luminescent substance combinations. First, the luminescent substances as in the embodiment of FIG Fig. 4 selected so that all four luminescent colors 20W, 20R, 20G, 20B can be excited in the long-wave UV, while in the short-wave UV only the luminescent white 20W can be excited.

Regarding Fig. 5 (a) a camouflage area 62 is defined in the desired colored motif 60, which in the exemplary embodiment is designed in the form of the lettering "Original". Within the camouflage area 62, the real colors of the motif are generated without the use of luminescence white 20W only with the luminescence basic colors 20R, 20G, 20B, as in FIG Fig. 2 (a) and the color pixel 30 of the Fig. 3 shown. In the normal area 64 lying outside of the camouflage area 62, the real colors of the motif are on the other hand generated using luminescent white 20W as referring to FIG Fig. 2 (b) and the color pixels 32, 34 of the Fig. 3 explained. Advantageously, the achromatic component 22 of the real colors in the normal area 64 is even completely formed by luminescent white 20W.

As in Fig. 5 (b) illustrated, the motif 60 in the present case comprises a representation 66 luminescent in real colors in front of an (optional) white luminescent background 67. The background 67 can, as will be seen later Fig. 6 described with advantage, available in grayscale. The camouflage area 62 should be arranged completely or - as shown - at least partially within the real-color display 66. A camouflage area 62 lying outside of the real-color representation 66 is conceivable but significantly less secure.

If the print obtained in this way is exposed to long-wave UV radiation 42 from a UV lamp 40, all four luminescent colors 20W, 20R, 20G, 20B are excited and luminesce in the corresponding color white, red, green or blue. The real colors are only generated in the camouflage area 62 by the luminescence basic colors 20R, 20G, 20B. In the normal area 64, the real colors of the representation 66 are generated with the additional use (and / or the background 67 with the sole use) of luminescent white 20W. Since all luminescent colors light up and the replacement of the achromatic component 22 by luminescent white does not lead to a change in the hue of the true color, the camouflage area 62 fits seamlessly and without any contrast or color difference into the overall motif in true color representation 66 (and into the white background). In the long-wave UV light 42, the camouflage area 62 is therefore not recognizable.

If, on the other hand, short-wave UV radiation 46 from a UV source 44 is applied to the print, only the luminescent white 20W becomes luminescent excited, while the short-wave non-excitable colored luminescent substances 20R, 20G, 20B do not shine. As related to Fig. 4 (b) explained, the print shows an achromatic motif in the normal area 64, which represents a gray level reduction 52 of the multicolored butterfly motif. In the camouflage area 62, however, the imprint is formed entirely without the use of luminescent white 20W, so that the camouflage area 62 does not glow in the event of short-wave UV excitation and thus does not participate in the reconstruction of the motif.

As in Fig. 5 (c) As illustrated, the camouflage area 62 thus appears dark in front of the normal area 64 luminescent in gray (and / or white). The overall appearance 68 then shows an overlay of the gray level reduction in the normal area 64 with the non-luminescent camouflage area 62, the black lettering "Original ". The optional background 69 analogously comprises non-luminescent partial areas of the camouflage area 62, here in the form of parts of the lettering "Original", as well as the white (or for example uniformly light gray) luminescent parts of the normal area 64 that remain unchanged and form a background.

Figure 6 shows schematically a further special protection of a luminescent print 70. The print 70 comprises a first sub-area 72 with a multicolored motif and a sub-area 74 in gray levels. The imprint 70 shows a colored motif in a first partial area 72 in UV light, in which achromatic portions of colored areas are formed at least partly by luminescent white and partly by the luminescent basic dyes, such as luminescent green, luminescent red and luminescent blue, in the type described in more detail above .

In addition, the imprint 70 in the second partial area 74 shows the same UV light is a pure grayscale pattern with different brightness values. The grayscale pattern is preferably selected such that the brightness values smoothly merge into one another, cover a large range of possible brightness values and / or have a large number (at least 5, preferably at least 10) of different brightness values. Schematically shown as sub-area 74 is FIG Fig. 6 a gray level wedge, as an example of a steplessly formed gray level area. The different brightness values can be achieved by varying the layer thickness and / or the area (as indicated in the figure) of the print.

The pure gray level pattern can also be formed, for example, by a gray level reduction of the colored motif of the first sub-area 72. It is essential that the imprint 70 in the second partial area 74 is printed only by luminescence white without the use of the luminescence basic dyes luminescence green, luminescence red and luminescence blue. In the UV light, the imprint 70 simultaneously shows a colored motif in sub-area 72 and a pure gray-scale image in sub-area 74.

If the imprint 70 is reproduced by a forger with conventional luminescent substances, that is to say using only the luminescent basic dyes 20R, 20G, 20B, the gray levels of the sub-area 74 must each be produced by a combination of the luminescent basic dyes. However, due to the specific properties of the luminescent basic dyes, it is generally impossible to produce correct achromatic tones in several brightness levels with certain luminescent basic dyes. Rather, a residual color, which is dependent on the brightness value of the gray levels, and for which the human eye is very sensitive and which therefore even an inexperienced observer can do without, arises in sub-area 74 further is perceived. A reproduction of the imprint 70 is therefore easy to distinguish from a real imprint 70.

The multicolored sub-area 72 can be arranged within the gray-level sub-area 74. The grayscale sub-area 74 can thus preferably form a background for the multicolored sub-area 72.

List of reference symbols

10

Banknote

12

Security element

14th

luminescent print

16

Substrate

20R

Luminescent red

20G

Luminescent green

20B

Luminescent blue

20W

Luminescent white

22nd

Achromatic component

24

Colored portion

26R, 26G, 26B

reduced color components

30, 32, 34, 36

Color pixels

40

long wave UV lamp

42

long-wave UV radiation

44

short-wave UV source

46

short-wave UV radiation

50

multi-colored motif in real color

51, 67

luminescent background

52

Grayscale reduction of the multicolored motif

60

colored motif

62

Camouflage area

64

Normal range

66

Overall motif in real color

68

Overlay camouflage area with appearance

69

Overlay camouflage area with background

70

luminescent print

72, 74

Sub-areas

Claims (15)

1. Security element (12) for securing security papers, value documents and other data carriers, having a luminescing imprint (14), wherein

   - the luminescing imprint (14) is formed by, on the one hand, printed luminescent white (20W), a luminescent substance luminescing white, and at least two printed luminescent primary colorants (20R, 20G, 20B) on the other hand,

   characterized in that

   - the luminescing imprint (14) shows a multicolored motif (50, 60, 70) in the UV light, and

   - the multicolored motif (50, 60, 70) contains achromatic portions (22) also in colored regions, which in the imprint are formed at least partly by luminescent white (20W).
2. A security element according to claim 1, characterized in that the luminescing imprint (14) is formed by luminescent white (20W) on the one hand, and three luminescent primary colorants on the other hand, in particular luminescent green (20G), luminescent red (20R) and luminescent blue (20B).
3. The security element according to claim 1 or 2, characterized in that the achromatic portions (22) of the multicolored motif are formed at least in a partial region of the motif completely by the luminescent white (20 W).
4. The security element according to at least one of claims 1 to 3, characterized in that the luminescent white (20W) is formed before printing by a mixture of two or more luminescent substances.
5. The security element according to at least one of claims 1 to 4, characterized in that the luminescent substances forming the luminescent white (20W) have a surface functionalization of the same kind by a face coating, or are present in a shared capsule.
6. The security element according to at least one of claims 1 to 5, characterized in that the luminescent white (20W) is excitable in a first UV excitation range together with the luminescent primary colorants present in the imprint (20R, 20G, 20B), and is excitable in a second UV excitation range without the luminescent primary colorants present in the imprint (20R, 20G, 20B).
7. The security element according to claim 6, characterized in that the luminescing imprint (14) upon excitation in the first UV excitation range shows the multicolored motif (50) and upon excitation in the second UV excitation range shows a grayscale reduction (52) of the multicolored motif.
8. The security element according to claim 6 or 7, characterized in that the luminescent primary colorants (20R, 20G, 20B) contain an absorber for the second UV excitation range.
9. The security element according to at least one of claims 1 to 8, characterized in that the achromatic portions (22) of the motif are formed in a camouflage region (62) of the motif (60) only by the luminescent primary colorants (20R, 20G, 20B).
10. The security element according to any of claims 6 to 8 and according to claim 9, characterized in that the camouflage region (62) upon excitation in the first UV excitation range is unrecognizable and upon excitation emerges visibly in the second UV excitation range.
11. The security element according to at least one of claims 1 to 10, characterized in that the luminescing imprint (14) in the UV light shows, beside the multicolored motif (72), a grayscale pattern (74) having different lightness values, which is formed without employment of the luminescent primary colorants by the luminescent white.
12. The security element according to at least one of claims 1 to 11, characterized in that the luminescing imprint (14) is imprinted on a substrate (16) substantially not luminescing upon UV excitation.
13. The security element according to at least one of claims 1 to 11, characterized in that the luminescing imprint (14) is imprinted on a substrate (16) luminescing upon UV excitation, and is provided in partial regions with a UV absorber to locally inhibit the substrate luminescence.
14. A data carrier (10) having a security element (12) according to at least one of claims 1 to 13.
15. A method for manufacturing a security element (12) for securing security papers, value documents and other data carriers (10), having a luminescing imprint (14), which shows a multicolored motif in the UV light, wherein in the method

    - the luminescing imprint (14) is formed on the one hand by printing luminescent white (20W), a luminescent substance luminescing white, and on the other hand by printing at least two luminescent primary colorants, for example from the group consisting of luminescent green (20G), luminescent red (20R) and luminescent blue (20B), and

    - the multicolored motif contains achromatic portions (22) also in colored regions, which in the imprint are formed at least partly by luminescent white (20W).

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