WO2010012508A1

WO2010012508A1 - Gonioluminescent security element and method for producing it

Info

Publication number: WO2010012508A1
Application number: PCT/EP2009/005718
Authority: WO
Inventors: Christian Kunath; André LEOPOLD; Henrik Ramuta
Original assignee: Bundesdruckerei Gmbh
Priority date: 2008-08-01
Filing date: 2009-07-31
Publication date: 2010-02-04
Also published as: EP2307206A1; ATE539899T1; DE102008036402B3; WO2010012508A8; EP2307206B1; RU2493969C2; CN102083633A; PL2307206T3; RU2011107349A; CN102083633B

Abstract

The invention relates to a gonioluminescent security element (1) and to a method for producing such a security element, which is preferably embodied as a security document. The security element (1) comprises a first element (3) and a second element (5), which at least partly overlaps the first element (3), wherein the second element (5) faces an observation side (4) of the security element (1), wherein the first element (3) comprises first luminescence means and the second element (5) comprises at least one optical interference structure which has an orientation-dependent transmittance (11, 12) and/or reflectance (11, 12) in a distinguished wavelength range (14) wherein the first element (3) and the second element (5) are coordinated with one another in such a way that an optical change can be perceived in the case of observation during excitation of luminescence of the luminescence means depending on an orientation of the observation and/or a direction of incident radiation of excitation light through the second element (5), wherein the at least one interference structure changes its transmittance and/or reflectance in the distinguished wavelength range for precisely one orientation or in a delimited orientation range.

Description

Gonioluminescent security element and process for its preparation

The invention relates to a gonioluminescent security element, which is preferably designed as a security document or integrated in such, and a method for producing a gonioluminescent security element.

As security elements structures and structural units are considered, which have at least one security feature. Security features are again features that make it difficult or preferably impossible to imitate, falsify, duplicate or the like. Security features should also allow verification of themselves, for example, to verify their authenticity and / or authenticity.

In addition to checking for authenticity of the security element, information that is secured by the security element or the security feature directly against adulteration and / or imitation can often also be coded in a security element.

Security documents are entities that comprise at least one security feature. By way of example only: identity cards, passports, ID cards, access cards, visas, tax stamps, tickets, driving licenses, motor vehicle papers, documents of value such as banknotes, checks, postage stamps, bank cards, credit cards, any smart card and adhesive label (e.g. Such security documents have at least one security feature, usually a plurality of different security features. In the security document already prefabricated, designed as a semi-finished, security elements can be integrated, such as an exposed or embossed hologram. However, individual components or elements can also be integrated into a security document, which together contribute to the development of a security feature.

A security document therefore always represents a security element in a broader sense since it is a structural unit with at least one security feature. In the prior art, a variety of security features and security elements are known. For example, from the prior art security elements or security documents are known in which information with so-called optical variable color (OVI - Optically Variable Ink) are printed. An optically variable color is characterized in that different color impressions or color valencies of the printed information are perceived at different viewing angles.

Also known in the art are security documents or security elements that include structures that exhibit viewing angle dependence due to interference effects. Such security elements include i.a. For example, volume holograms, which generally have a high angular selectivity with respect to a reconstruction of the information stored in the volume hologram. Volume holograms are further characterized by a high wavelength selectivity with respect to the reconstruction light, with which a reconstruction of the hologram is possible.

From DE 60114156T2 effect pigments are known in which in addition luminescent substances are incorporated into the effect pigments. A disadvantage here is the fact that one has to submit to the "constraints" (layer thickness, refractive index of the core material) during the construction of the effect pigment and therefore no sufficient and significant optical effect occurs during tilting For this purpose, for example, the use of typical luminophores with particle sizes of several μm in diameter is precluded, and typical host lattices have a higher luminophoricity for luminophores Refractive index compared to typical OVI core materials such as MgF ₂ , which severely restricts the color change effect on tilting, and consequently typical luminophore host lattices are not suitable for the construction of OVI materials.

Despite the already known number of angle-dependent security features and security elements, there is still the need to provide novel security features and security elements to a counterfeit security of To provide security documents and items secured with a corresponding security feature. In particular, it is desirable to provide a simple and reliable security feature to be tested.

The invention is thus based on the technical object of providing a security element which has an angle-dependent security feature which is easy to check and to provide a method for its production.

To solve the technical problem is provided to provide a gonioluminescent security element comprising a first and a second element, which overlap at least partially. Here, the second element faces a viewing side of the security element, from which the security element is considered during a verification. While the first element comprises first luminescent means, the second element comprises at least one optical interference structure having an orientation-dependent transmittance or reflectivity in an excellent wavelength range, which causes a noticeable change in the observed luminescent light upon a change in orientation exactly at an orientation angle or in a limited orientation angle range. The first element and the second element are so matched to each other that when viewed during excitation of luminescence of the first luminescent means depending on an orientation of viewing and / or direction of irradiation of an excitation light through the second element, optical change is excellent Orientation or a limited orientation range is perceptible. This means that for the excellent coherent wavelength range at exactly one orientation or an orientation range, a change in the transmission or reflection occurs. To produce such a gonioluminescent security element, a first and a second element are arranged relative to one another, so that the second element at least partially overlays the first element and the second element faces a viewing side. Here, a tuning of the first element to the second element or vice versa must be such that the excited state luminescent means in the excellent wavelength range emit light or the excellent wavelength range coincides with a wavelength range in which the first luminescent means by means of an irradiation of excitation light to a luminescence can be excited. In the former Trap is changed by a change in the transmittance or reflectivity, the luminescence light with respect to its intensity in the excellent wavelength range by the second element orientation-dependent. On the other hand, in the second case, an excitation of the luminescence as such is altered as a function of the orientation. The second element comprises at least one interference structure that changes its transmission or reflection for at least one wavelength or wavelength range in exactly one orientation or in a limited orientation region. This wavelength or wavelength range corresponds to the above-described excellent wavelength or wavelength range, which in turn corresponds, for example, to an emission wavelength or to an emission wavelength range under which the phosphor luminesces or to the excitation wavelength or the excitation wavelength range. That is, the interference structure changes its transmissivity and / or reflectance for the light in the excellent wavelength region at exactly one orientation and in just one orientation region, respectively. An advantage of the invention is that a viewing angle-dependent security element is created, which can usually be checked by a simple visual inspection with the aid of an excitation source for the luminescence. Since there is exactly one orientation or a limited orientation range under which the observable or considered luminescence light changes its intensity or spectral composition during a change in orientation, for example when a security document is tilted, such a security feature can also reliably be provided by untrained or under-trained persons Persons are verified. Excellent orientation is determined by an angle (polar angle) relative to a perpendicular of a surface. An azimuth angle, ie an angle in the surface plane between an arbitrary axis in the plane and a projection of a viewing or irradiation direction in the plane, however, can be arbitrary. In the case of using volume holograms, the azimuth angle range may also be limited. A limited orientation range is defined by a limited angular range for a polar angle of the viewing or irradiation direction. The at least one interference structure can be formed from a plurality of identical constituents, which however each independently show a corresponding interference behavior which has the overall structure. This means that the components have an analogous orientation-dependent transmission and / or reflection behavior. The term "change in transmittance and / or reflectance for the light in the excellent wavelength range in exactly one orientation or in exactly one orientation range" is to be understood as meaning that a change in orientation leads to a transition from a transmissivity and / or reflectivity to a another of these different transmissivity and / or reflectivity is fed, if the exactly one orientation or a limited orientation range are reached.

However, occurrence of an orientation-dependent change in transmittance or reflection in an excellent wavelength region in just one orientation or in a limited orientation region does not mean, in all embodiments, that a change in the observable luminescent light occurs only under precisely that orientation. Rather, the at least one interference structure can also be chosen such that the reflection and / or transmission changes in exactly one orientation, but then remains substantially constant in the case of a continued orientation change. For polar angles measured against the perpendiculars, which are smaller than the polar angle associated with the excellent orientation, the at least one interference element exhibits, for example, a first transmission and / or reflection behavior in the excellent wavelength range. At polar angles greater than that associated with the exactly one orientation, the at least one interference element has a different transmission and / or reflection behavior in the excellent wavelength range. The change between the transmission and / or reflection behavior occurs in exactly one orientation. The same applies to an orientation range in which a transition between the different reflection and / or transmission behavior occurs.

In other embodiments, the transmission behavior and / or reflection behavior in the excellent wavelength range is the same for all orientations except for exactly one orientation or the limited orientation range at which the transmission behavior and / or reflection behavior for light is excellent Wavelength range changes.

Further advantageous is the separation according to the invention of the angle-dependent element from the luminescent element, ie the use of two independent ones Elements, whereby both elements can be separately optimized or selected in order to achieve a significant visual effect in interaction.

The inventive separation of the first element and the second element here is a much greater freedom of choice in the selection and combination of elements. Thus, luminophores can be used regardless of their physical or chemical properties (such as refractive index, particle size, host lattice ...); or also, for example, organic and inorganic luminophores simultaneously.

The at least one interference structure used for the second element has a preferred direction in each case.

In order to make a visual inspection by a human in this way possible, it is provided in a preferred embodiment of the invention that the excellent wavelength range is in the visible wavelength range. In such a case, the second element is preferably designed such that there is no orientation-dependent influencing of the transmission or reflection with respect to an irradiation of excitation light through the second element. Thus, an observation of the security feature according to the invention in a simple manner possible by the security element is considered at different angles.

In order to be able to reliably perceive the orientation-dependent change, it is provided in a preferred embodiment that an orientation-dependent change in the transmittance and / or reflectivity of more than 30%, preferably more than 50%, most preferably more than 80%, can be effected. The orientation-dependent change is particularly easy to perceive if the element comprises at least two (laterally) adjoining regions, of which at least one of the at least two regions is not overlapped or covered by the second element. An orientation-dependent change in the perceived luminescence occurs in a change in orientation only in the region or regions of the first element which are overlapped by the second element. For example, since the human eye is well-suited to perceive relative differences in hue and / or intensity, the orientation-dependent change of the perception is particularly easily detected in this embodiment. The first element may comprise first luminescent means which have a narrowband or a broadband luminescence spectrum. In general, the first luminescent means will comprise a narrow-band luminescence spectrum with one or more spectral lines arranged adjacent or spaced apart in the wavelength spectrum. A coordination of the first element, ie the first luminescent means, with the second element, ie the excellent wavelength range in which an orientation-dependent change of the reflectivity and / or transmittance takes place, takes place in the embodiments in which the luminescence spectrum is influenced by the orientation dependence, such that the first luminescent means emits luminescent light in the excellent wavelength range, preferably has a maximum of the luminescence of the first luminescent means.

In order in particular to be able to determine a specific color of the luminescence, it is advantageous to add further luminescence agents to the first element. These have a spectral distribution deviating from the spectral distribution of the first luminescence medium. For example, to effect a color change that can be perceived by a viewer even without a comparison region of the first element not covered by the second element, it is advantageous if the second element is designed so that the orientation-dependent transmissivity and / or reflectivity in the excellent Wavelength range is spectrally selective with respect to a larger, the excellent wavelength range comprising wavelength range. A spectrally selective orientation dependence means that the change of the transmission and / or the reflection occurs only in a limited wavelength range, here the excellent wavelength range. This means that the change of the reflectance or transmittance varies orientation-dependent only in the excellent wavelength region. In an adjacent spectral range or wavelength range, however, no or only a much smaller change in the transmission and / or reflectivity is observed. This results in a luminescent light which is broadband and / or consists of several spectral lines, which are not all in the excellent wavelength range, that only for a part of the spectral lines or the spectral range or wavelength range of the luminescent an orientation-dependent change in transmittance and / or the reflectivity occurs. As a result, a color impression is changed depending on the orientation, since a color impression perceived by the observer of the luminescence light depends on the color addition of the spectral composition of the luminescence light. If only one spectral component is transmitted or reflected by the second element, this leads to a change in the spectral composition of the perceptible spectral distribution and, as a result, to a color change.

In a preferred embodiment it is provided that information is stored in the security element. This can be, for example, individualizing and / or personalizing information. As individualizing information, those are considered which make it possible to distinguish the security feature from another similar security feature. An individualizing information can be, for example, a serial number. As personalizing information, such individualizing information is considered that includes information of a person to whom the security element is assigned. For example, when the security element is integrated into a document used as a passport, a name encoded in the security element, a date of birth, biometric data such as face image information, fingerprint information, etc. may be used as personalizing information. An individualization and / or personalization is possible, inter alia, both via a planar structuring of the first element and a planar structuring of the second element and / or a structuring of the overlapping region. Preferred embodiments thus provide that a first information in the first element and / or a second information in the second element are stored. The use of the terms first and second information in this context does not constitute a prioritization of the information.

As first and / or further luminescent agents, it is possible to use all substances and agents known to the person skilled in the art which can be stimulated to luminesce. Preferably, luminescent agents are used which exhibit fluorescence or phosphorescence. Luminescence may be photoluminescence, electroluminescence, including light emission from organic or inorganic light emitting diodes, or radioluminescence. Preference is given to luminescent agents which are transparent in the visible wavelength range, so that the first element in the visible wavelength range is transparent. Hereby, it can be achieved that a print layer or a print layer, which is possibly placed on an object provided with the security element, mounted under the first element as viewed in the security element from the viewing side, is not impaired in perception, as long as Luminescence is not excited. Furthermore, the luminescent agents can also be contained in a visible printing ink (body color).

The second element is transparent or partially transparent in each case in a spectral region of the luminescence as well as in a spectral region of the excitation light under at least one orientation.

The second element may comprise one or more optical interference structures. As suitable interference structures, multilayer interference structures have been found. For example, coextruded films adapted to have a high transmittance below an excellent wavelength and a low transmittance above the excellent wavelength can be used. The same can also be formed for the reflectivity. It is also possible to have a low transmittance below the excellent wavelength and a high transmittance or corresponding reflectance, respectively. Such structures are known in the art as so-called short-pass filters or long-pass filters. These structures have the property that, at an excellent wavelength, a change in transmittance and / or reflectivity occurs in a perpendicular viewing of the layers. If the orientation is changed from the perpendicular observation, the excellent wavelength shifts to shorter wavelengths. The range in which this excellent wavelength shifts as the orientation changes determines the excellent wavelength range of the interference element.

A similar behavior is exhibited by so-called effect pigments, in particular multilayer interference electronic effect pigments comprising a plurality of dielectric layers deposited or deposited on mica particles, for example, or Fabry-Perot metal-dielectric effect pigments in which a dielectric particle is coated with semipermeable metal layers. The effect pigments will be manufactured so that they have an intrinsic preference orientation. This means that they intrinsically have a preferred direction which, for example, is equivalent to the perpendicular in coextruded films. In making the effect pigments, the starting particles are selected to have a greater areal extent along a plane than in any other possible orientations in the space. When forming the second element, a plurality of identical or different interference structures can be used, but these are at least largely aligned with respect to their intrinsic preferred orientation relative to each other at least. In addition to long and short pass filters, it goes without saying that bandpass filters can also be used which only pass or block a certain wavelength range, which also shifts when tilted. Further possible interference structures can be generated, for example, by means of liquid crystals. Likewise, volume holograms or Lippmann Bragg structures can advantageously be used. Volume holograms, for example, offer the advantage that complex information can be stored in them independently of a planar structuring during production, which information can be read out during a reconstruction. A reconstruction now only takes place in the case of the security element according to the invention if a viewing angle coincides with a reconstruction angle determined during production. Furthermore, different information for different spectral lines can be stored in a volume hologram, which can also reconstruct at different viewing angles and illumination angles. However, it is essential that a volume hologram is designed such that an orientation-dependent change in the transmission and / or reflection occurs for a defined wavelength range in an orientation or in an orientation range.

Of course, embodiments are possible in which the second element comprises different interference structures.

The individualization and / or personalization of the security element is particularly easy, since at least the first element is preferably produced by printing technology. Luminescent agents can be easily integrated into printing inks and / or printing inks. In a particularly preferred embodiment, the second element is produced by printing technology. In particular, the effect pigments mentioned, but also liquid crystals which form a cholesteric phase or flakes of co-extruded materials (for example, coextruded films or glasses) can be applied by printing technology. Here, the fact that the intrinsic orientation is accompanied by a geometrical configuration, at least in the case of the effect pigments and the flakes which have a preferred direction, so that a geometrical arrangement on a surface leads to the individual interference structures being relative to one another and to the first element or to the first element align a viewing direction together. However, it is important that an interference structure that consists of several constituents, which likewise comprise all the interference structures, has a preferred direction only in respect of one spatial direction (the perpendicular of the surface). This is the only way to ensure that a change in transmission and / or reflection changes for a selected wavelength range occurs only in exactly one orientation, ie at a polar angle relative to the perpendicular.

If a volume hologram or coextruded films are used as the interference structure, it is possible to apply these to the finished value document, wherein luminescent substances are contained in the value document as the first element and an optical effect according to the invention occurs in interaction. If a volume hologram or coextruded films are used as the interference structure, it is possible to print the first element on the holographic recording medium of the volume hologram or on the coextruded films, the printed side in each case representing the side of the second element facing away from the viewing side of the security element. In other embodiments, the first element is preferably applied to a substrate by printing technology. The substrate can be any substrate layer known to the person skilled in the art, in particular based on plastic, textile base and / or paper base. Examples of plastics are, for example, representatives of the group comprising PC (polycarbonate, in particular bisphenol A polycarbonate), PET

(Polyethylene glycol terephthalate), PMMA (polymethyl methacrylate), TPU (thermoplastic polyurethane elastomers), PE (polyethylene), PP (polypropylene), PI (polyimide or poly-trans-isoprene), ABS (acrylnitirl-butadiene-styrene), PVC (polyvinyl chloride) and copolymers of such polymers. The second element can be printed or applied directly onto the substrate printed with the first element. The application can eg via Adhesives that act thermally and / or UV-crosslinking happen. Alternatively, a lamination can take place in which the two elements or layers located between them adhere under the influence of pressure and temperature. However, it is likewise possible to arrange transparent substrate layers which are transparent or at least partially transparent or luminescent both in the wavelength range of the excitation light and in the luminescent light, between the first element and the second element.

A particular advantage with a suitable choice of the interference structures is that the security element can be applied to virtually any substrate using printing means and methods. In this case, it is easily possible to store information, in particular also individualizing and / or personalizing information, and to secure it in the security element.

Likewise, embodiments are conceivable which comprise a third element, which likewise comprises at least one interference structure and partially overlaps the first element. As a result, security elements can be created which, for example, simultaneously effect an orientation-dependent inverse color change in different areas of the security element, ie. in case of a change of orientation, to be brought about.

The invention will be explained in more detail with reference to a drawing. Hereby show:

Fig. 1a is a schematic view of a security element in sectional view;

Fig. 1b is a schematic plan view of the security element according to Fig. 1a;

Fig. 2a is a schematic sectional view of the security element of FIG. 1 at

Excitation with UV radiation and vertical viewing;

Fig. 2b is a plan view of the security element of Fig. 2a; 3a shows a schematic sectional view of the security element according to FIG. 1 during excitation with UV radiation and viewing under a different orientation than a perpendicular view;

Fig. 3b is a plan view of the security element of Fig. 3a;

4 is a graph of reflectivity /

Transmittance versus wavelength versus different viewing angles; and

5a-5c are schematic plan views of another security element when viewed perpendicularly without excitation of a luminescence (a), when viewed perpendicularly with excitation of the luminescence (b) and viewing under a deviating from a perpendicular orientation upon excitation of the luminescence.

In Fig. 1a, a security element 1 is shown schematically. On a substrate 2, a first element 3 is applied, preferably printed. The first element 3 comprises one or more luminescent agents, which exhibit luminescence in the visible wavelength range after or with shorter-wavelength light excitation, for example, with a light source. B. in the UV wavelength range show. An imprinting of the luminescent means can be carried out, for example, by means of a high-pressure, intaglio, gravure, digital printing or planographic printing, in particular offset printing, process, which is a wet offset printing method, waterless offset printing method or dry Offset printing process can be. For individualizing or personalizing imprints, for example, an inkjet printing process is suitable. Above the first element 3, facing a viewing side 4 of the security element 1, a second element 5 is arranged, which overlaps the first element 3 at least partially, ie covers it. The second element 5 comprises one or more interference structures. The interference structures may be, for example, coextruded films. Likewise, the interference structures may be multilayer interference effect pigments of dielectric layers or metal-dielectric Fabry-Perot effect pigments or liquid crystals forming a cholesteric phase, or combinations thereof. The latter interference structures are most easily applied by means of a printing process, for example screen printing. However, it can also be arbitrary Other printing methods may be used as long as the interference patterns are printed such that they respectively align with respect to the first element, so that an intrinsic orientation with respect to an orientation-dependent interference property is identical or nearly identical for all of the plurality of interference structures. If, for example, dielectric multilayer interference effect pigments are used, they have a transparent core, for example a mica particle, which is coated with a plurality of dielectric layers. The mica particle has a surface extent in a spatial plane that is larger than in all other possible spatial directions. This means that the multilayer dielectric interference effect pigment has a flattened shape. In printing such dielectric multilayer interference effect pigments, they are oriented with their flat side substantially parallel to the substrate or a planar surface of the first element or a substrate layer arranged between the first element and the second element. The uniform orientation of a plurality of dielectric multilayer interference effect pigments is necessary, so that macroscopically an orientation-dependent, ie viewing angle-dependent, interference effect occurs, which causes a visually perceptible change of the security element, as will be explained in more detail below. The same applies to flakes of co-extruded materials which have a geometric shape which is adapted to a preferred direction of the interference properties. That is, a preferred geometric direction is defined with respect to a preferred direction of interference. For example, flakes of coextruded materials have a flat shape. For example, a normal to a surface defined by the flat shape coincides with a perpendicular with respect to which the directional reflectance and / or transmittance of the coextruded material is defined. The security element 1 may comprise further layers in other embodiments and is itself preferably designed as a security document, for example a passport or identification document, or as a value document or the like. In the illustrated embodiment, an adhesion promoter layer 6 is arranged below the substrate layer 2, so that the security element 1 can be applied to other security documents and / or objects, for example by means of a hotstamp process. Other possibilities for the development of the adhesion promoter layer are, for example, the adhesive described in DE 10 2006 048 464 A1, which can be dried in a first stage with the aid of UV crosslinking, whereby the element can be stored, for example, block-free in roll form, and in the second stage , eg during a lamination process, thermally bonding to the underlying substrate. Alternatively, this substrate can of course also be used to print or coat the substrate, possibly over part of its surface, so that it subsequently bonds adhesively to the adhesive-free security element during lamination. Another example is the method described in DE 10 2007 052 949 A1, in which the element or the substrate is mixed with a mixture of solvent or solvents and a geminally disubstituted polycarbonate derivative

Dihydroxdiphenylcycloalkans coated, dried, and then with the other layer e.g. is adhesively bonded by lamination.

It will be clear to the person skilled in the art that first and second information can be stored in a simple manner both in the first element and in the second element. This applies in particular if these elements are produced by printing technology. During printing, it is possible, for example, to design a planar structuring of the first element and of the second element virtually as desired and to encode information about this, for example in the form of alphanumeric characters and / or graphic symbols and / or images. If coextruded films are used as interference structures, they can likewise be structured in a planar manner, for example by punching out or the like. If a volume hologram is used as the interference element, information can be stored in the volume hologram, as is known to the person skilled in the art, only from a reconstruction of the hologram under a predetermined reconstruction geometry which includes an incident direction of the reconstruction light and a viewing direction can be read out.

Preferably, the luminescent means comprising the first element are formed so that they are transparent in the visible wavelength range. The second element is also designed such that it is transparent or partially transparent at least in a partial region of the visible wavelength spectrum. As a result, it is u.a. it is possible for an information stored in the substrate 2, which is applied, for example, by means of a conventional printing layer (not shown), to be visible to an observer as long as luminescence of the first element is not excited.

In order to test and / or verify the security element 1, the security element is irradiated with excitation light 7. This is light in the ultraviolet Wavelength range which is tuned to the luminescent means of the first element 3 in such a way that it causes a luminescence of these luminescent means. In Fig. 2a this situation for the security element 1 according to Fig. 1a is shown. By means of solid arrows, the luminescent light 8 is shown, which perceives a viewer in a vertical plan view of the security element 1. However, the excitation light 7 may also be, for example, in the visible wavelength range (so-called daylight fluorescence). Even with excitation in the infrared wavelength range, it is possible, for example, to emit visible light with the aid of anti-Stokes properties.

In Fig. 3a, the situation is now shown in which the security element 1 is also irradiated with excitation light 7, so that in the first element luminescent light 8 is generated. In this case, however, luminescent light 8 is now shown, which perceives a viewer at another deviating from the perpendicular viewing orientation. At least part of the luminescent light 8 'is formed in the second element 5, i. in the interference structure (s). This means that a transmissivity of the interference structure or interference structures of the second element 5 decreases as the orientation changes.

Schematically, the transmittance / reflectivity of an interference element is shown in FIG. There, a transmittance (reflectivity) versus wavelength is shown for vertical viewing 11 (solid line) and for viewing below 60 ° 12 with respect to a surface plumb line (dashed line). At an excellent wavelength 13, a transient change in transmittance (reflectivity) occurs when viewed perpendicularly. When tilted, this excellent wavelength 13 ', at which the sudden change of the transmission (reflection) occurs, moves to shorter wavelengths. A wavelength range in which a change in transmittance (reflectance) occurs is also referred to as an excellent wavelength region 14 or excellent spectral region. In order for an optically perceptible effect to occur when the security element is tilted during excitation of the luminescence, the luminescent means of the first element must be matched to the interference structures of the second element in such a way that significant emission of the luminescent light takes place in this excellent spectral region or wavelength region 14. If the luminescence spectrum of the first element has a line spectrum, then this is preferably one of the spectral lines of the luminescence spectrum in the excellent spectral or wavelength region 14.

In the embodiment illustrated in FIGS. 1a to 3a, it is assumed that the first element, i. the one or more interference structures of the first element, have a reflectivity which increases with a tilt in the wavelength range of the luminescent radiation 8, or a transmittance which decreases. As is known to those skilled in the art, different interference structures can be formed which also exhibit opposite behavior, which means high transmission (low reflectance) at short wavelengths and low transmission (high reflection) at long wavelengths. Of course, bandpass filters can also be generated analogously.

FIGS. 1 b to 3 b show schematic views of the security element 1 according to FIGS. 1 a to 3 a, which correspond in each case to one another. In Fig. 1 b it can be seen that the second element 5, the first element 3 is only partially superimposed and beyond structured, for example, could be interpreted as a bar code. In the view of FIG. 1 b, a luminescence is not excited.

FIG. 2b shows a vertical plan view of the security element, in which the luminescence of the luminescence means of the first element 3 is excited. An emission of the luminescent light is indicated by a hatching. A stroke width of the hatching indicates an intensity of the perceived luminescent light. It can be seen clearly that a strong luminescence is perceptible in the entire areal extent of the first element 3.

FIG. 3b now shows a plan view under an orientation deviating from the perpendicular observation upon excitation of the luminescence. It can be seen that in the covered areas 9, in which the second element 5 overlaps the first element 3, a significant weakening of the luminescence has occurred. As a result, the structure of the second element 5 as a darkened area, which corresponds to the covered area 9, becomes perceptible to an observer, who was not visible in a plan view according to FIG. 2b, since the second element 5 is transparent there. Shown in FIGS. 5a to 5c are schematic plan views of a further embodiment of a security element 1. In the illustrated embodiment, information is encoded in the first element 3, which is shown schematically as A here. The second element 5 is formed so as to overlap only a part, a half 15, of the first element 3.

In the view according to FIG. 5a, in which a luminescence is not excited, the information of the first element 3 is imperceptible, as long as the luminescence means of the first element 3 are transparent in the visible wavelength range.

FIG. 5b now shows the situation in which the luminescence of the luminescence means of the first element 3 is excited. The security element 1 is considered under a vertical plan view. The luminescence in the entire region of the first element 3 can be clearly recognized. Thus, in this view, the information stored in the first element 3 is clearly perceptible.

In Fig. 5c is now a view of the security element 1 is shown, in which the security element 1 is considered under a different orientation. The interference structure or the interference structures of the second element 5 have almost no transmission in the region of the luminescence under this orientation. Therefore, only one uncovered half 16 of the letter A is perceptible by means of the emitted luminescence radiation. For the user, thus, a strong contrast, so that the security element is easy to verify.

The described embodiments are merely exemplary, greatly simplified embodiments. It will be understood by those skilled in the art that substantially more complex embodiments are conceivable. In particular, further elements can be applied which have interference structures which, for example, have an opposite transmission / reflection behavior to the second element and cover other parts of the first information.

If the luminescent means contained in the first element emit luminescent light in a large spectral range or in the form of a plurality of spectral lines which are widely spaced apart from one another in the wavelength spectrum, a viewing angle-dependent or tilt-dependent change of the luminescence light Reflectance or transmissivity only to a spectrally selective change. This means that the change in reflectance / transmissivity affects only luminescent light in a limited spectral range. However, with a suitable choice of the luminescence means, this leads to a clearly perceptible color change occurring during tilting. Of course, if not the entire first element is overlapped by the second element, the color change will only occur in a part of the first element at a tilt. Thus, even in such a case, the security element is easy to verify that in a portion of the first element a clearly discernible color change occurs.

The first information can also be stored "in color" in the first element, in particular if the first element comprises a plurality of different luminescent means, a part of the information can be created with the first luminescent medium which emits luminescent light which produces a first color impression However, since the second element has a spectrally selective orientation dependency of transmittance / reflectivity in the excellent wavelength region, if the luminescent agent is suitably selected, only the luminescent light of the first luminescent agent will become the other luminescent element emitting luminescent light of different color impressions The views shown in FIGS. 2 a and 3 a can also be interpreted in such an embodiment so that the luminescent light 8 differs has significant wavelengths. While, in a vertical plan view, compare FIG. 2 a, the luminescence light 8 of both wavelengths is transmitted, only the luminescent light 8 of one wavelength is transmitted in the tilted state (FIG. ^{3 a)} , whereas the remaining luminescent light 8 ¹ is reflected in the second element 5.

Particularly preferably, the described security elements are designed as security and / or value documents which comprise further security features and / or security elements. Alternatively, the security elements can be integrated into a security and / or value document.

It will be apparent to those skilled in the art that there are a variety of other design options for such a security element. Exemplary embodiments have been explained in more detail, in which the first element and the second element are preferably applied by printing technology. In other embodiments, however, the first element can for example also be integrated into a substrate or even represent the substrate on which the second element is applied. For example, luminescent agents can be integrated into the substrate, for example a plastic film. It is likewise possible to incorporate the luminescent agents in the form of mottling fibers or planchettes into a substrate. In particular, paper is suitable for the embedding of such elements.

If the paper also has a surface texture, e.g. by a tactile watermark, the second element applied to this surface structure adapts. The angle selectivity of the second element will therefore follow the shape of the surface structure during the verification of the feature. The surface structure is thus visible under luminescence excitation in incident light.

Furthermore, any suitable surface relief forms in the security feature according to the invention. Surface reliefs can arise z. B. by embossing the substrate, by intaglio, or by lamination z. B. by means of structured lamination.

When trained as plastic cards value and / or security documents, the production is typically carried out as a laminate. A typical method for producing such a security and / or security document then provides for the introduction of the described security element:

1) Provision of substrate layers of the above-mentioned plastics, typically in thicknesses between 10 .mu.m and 1000 .mu.m, preferably between 50 .mu.m and 250 .mu.m. The substrate layers may be printed, transparent, translucent, opaque, laser engravable, etc. Substrate layers having an inlay consisting of a non-contact chip and an antenna may also be used. One or all substrate layers may also have an adhesive layer. The substrate layers do not all have to be made of the same material. 2) On one of the substrate layers, the first element is applied, preferably printed.

3) On this substrate layer with the print, or on another substrate layer, e.g. a substrate layer formed as a transparent film, the second element is applied by one of the methods described above. Of course, in the case of application on the other substrate layer, this step does not necessarily have to take place after printing.

4) The substrate layer (s) having the first and second elements are brought into contact with the further substrate layers and laminated under the action of pressure and temperature. This forms a solid bond between the individual substrate layers, which is also referred to as a laminate.

5) The laminate is subsequently reworked z. B. in terms of its peripheral shape via a punching. In a production in multiple use is a separation, for example, also via punching, instead. Optionally, before or after stamping, the application of a protective film, e.g. a diffractive protective film, take place. There may also be a scratch-proofing layer, e.g. in the form of a varnish. Likewise, a combination of scratch protection layer and protective film can be used.

A special case is a subsequent application of the second element in step 5. In this case, the second element is not laminated in the card body, but is glued to it. In particular, if the second element is individualized or personalized, this can be beneficial. For example, a volume hologram can be applied partially or completely, part of which cooperates as a second element in the sense of the invention with an underlying luminescent element.

In still other embodiments, in which, for example, a volume hologram is exposed in a holographic recording medium, the first element can be printed by printing on a side facing away from the viewing side of the holographic recording medium. Preferably, the volume hologram is not exposed in the entire surface of the film, so that in this case, embodiments can be produced, in which the second element (the volume hologram) covers only a part of the first element. Similarly, when using coextruded films, a security element can be made. By way of example, a substrate, for example paper, printed with first luminescent means is provided with a second element, for example consisting of a coextruded film, by means of an application process (for example a hot stamp process), resulting in a gonioluminescent effect according to the invention. It is also advantageous if the coextruded film applied by the hot-stamp method has additional security features, for example carrier of a diffractive (partially) metallized surface embossing, and thus under normal incident illumination the typical optical effects of embossed holograms (such as a Kinegram® shows) and under UV illumination in combination with the underlying first luminescent element a gonioluminescent effect.

The elements and features described may be used in any combination to practice the invention.

LIST OF REFERENCE NUMBERS

1 security element

2 substrate

3 first element

4 viewing page

5 second element

6 adhesion promoter layer

7 excitation light

8, 8 'luminescent light

9 covered area

11 Transmittance / reflectance below 0 °

12 transmittance / reflectance below 60

13, 13 'excellent wavelength

14 excellent wavelength range / spectral range

15 covered half

16 uncovered half

Claims

claims

1. A gonioluminescent security element (1) comprising a first element (3) and a first element (3) at least partially overlapping second element (5), wherein the second element (5) facing a viewing side (4) of the security element (1) wherein the first element (3) comprises first luminescent means and the second element (5) comprises at least one optical interference structure having an orientation-dependent transmissivity (11, 12) and / or reflectivity (11, 12) in an excellent wavelength range (14) wherein the first element (3) and the second element (5) are matched to one another when viewed during excitation of luminescence of the first luminescent means depending on an orientation of viewing and / or direction of irradiation of an excitation light by the second Element (5) an optical change of the considered luminescent light is perceptible, wherein the at least s an interference structure in the excellent wavelength range at exactly one orientation or in a limited orientation range changes their transmissivity and / or reflectivity.

2. Gonioluminescent security element (1) according to claim 1, characterized in that the luminescence means in the excited state in the excellent wavelength range (14) emitting luminescent light (8, 8 ').

3. Gonioluminescent security element (1) according to claim 1, characterized in that the excellent spectral range (14) coincides with a wavelength range in which the first luminescent means by means of an irradiation of excitation light (7) are excitable to a luminescence.

4. Gonioluminescent security element (1) according to one of the preceding claims 1 or 2, characterized in that the excellent wavelength range (14) is in the visible wavelength range.

5. Gonioluminescent security element (1) according to one of the preceding claims, characterized in that an orientation-dependent change the transmissivity (11, 12) and / or the reflectivity (11, 12) of more than 30%, preferably more than 50%, most preferably more than 80% in the excellent wavelength range (14) is effected.

6. gonioluminescent security element (1) according to any one of the preceding claims, characterized in that the first element (3) next to the first luminescent means comprises further luminescent means which emit luminescent light with a deviating from the spectral distribution of the luminescent light (8) of the first luminescent spectral distribution.

The gonio-luminescent security element (1) according to any one of the preceding claims, characterized in that the orientation-dependent transmissivity (11, 12) and / or reflectivity (11, 12) in the excelent wavelength region (14) is spectrally selective with respect to a larger, the excellent wavelength region (14) is a comprehensive wavelength range.

8. Gonioluminescent security element (1) according to any one of the preceding claims, characterized in that the second element (5) comprises a plurality of optical interference structures, each having an intrinsic preferential orientation and with respect to these preferred orientations in the second element (5) relative to each other, at least as far as possible , are aligned.

9. Gonioluminescent security element (1) according to one of the preceding claims, characterized in that the one or more optical interference structures one or more effect pigments, in particular dielectric multilayer interference effect pigment or metal-dielectric Fabry-Perot effect pigments, coextruded materials ( Films, glasses) in the form of flakes or as large area patches or foils, volume holograms, liquid crystals, Lippmann Bragg structures or combinations thereof.

10. Gonioluminescent security element (1) according to one of the preceding claims, characterized in that in the first element (3) a first information is stored.

11. Gonioluminescent security element (1) according to one of the preceding claims, characterized in that the first element (3) is transparent in the visible wavelength range.

12. Gonioluminescent security element (1) according to one of the preceding claims, characterized in that the second element (5) in each case in a spectral region of the luminescence and in a spectral range of the excitation light (7) under at least one orientation is transparent or partially transparent.

13. Gonioluminescent security element (1) according to one of the preceding claims, characterized in that in the second element (5) a second information is stored.

14. Gonioluminescent security element (1) according to one of the preceding claims, characterized in that the first element (3) is applied to a substrate (2) and the second element (5) is applied to the first element (3) or to the substrate ( 2) are applied.

15. Gonioluminescent security element (1) according to one of the preceding claims, characterized in that a further transparent substrate is arranged between the first element (3) and the second element (5).

16. Gonioluminescent security element (1) according to one of the preceding claims, characterized in that the security element (1) is designed as a security document.

17. A method for producing a gonio-luminescent security element (1), wherein a first element (3) and a second element (5) are arranged relative to each other so that the second element (5) at least partially superimposed on the first element (3) and the second element (5) faces a viewing side, wherein the first element (3) comprises first luminescent means and the second element (5) comprises at least one optical interference structure which is orientationally dependent in an excellent wavelength region (14) Transmittance (11, 12) and / or reflectivity (11, 12), wherein the first element (3) and the second element (5) are coordinated so that when viewed during an excitation of a luminescence of the first luminescent depending on an orientation of the viewing and / or a direction of irradiation of an excitation light (7) by the second element (5), an optical change is perceptible, wherein the at least one interference structure is formed so that in the excellent wavelength range at exactly one orientation or in a limited orientation range changes their transmissivity and / or reflectivity.

18. The method according to claim 17, characterized in that the first element (3) and the second element (5) are coordinated so that the first luminescent means in the excited state in the excellent wavelength range (14) emit luminescent light (8).

19. The method according to claim 17, characterized in that the first element (3) and the second element (5) are coordinated so that the excellent spectral range (14) coincides with a wavelength range in which the first luminescent means by means of an irradiation of Excitation light (8) can be excited to a luminescence.

20. The method according to any one of the preceding claims 17 or 18, characterized in that the excellent wavelength range (14) is in the visible wavelength range.

21. The method according to any one of the preceding claims 17 to 20, characterized in that the second element (5) is formed, so that an orientation-dependent change of the transmittance (11, 12) and / or the reflectivity (11, 12) in the excellent Wavelength range (14) of more than 30%, preferably more than 50%, most preferably more than 80% is effected.

22. The method according to any one of the preceding claims 17 to 21, characterized in that the first element (3) in addition to the first Luminescent means comprises further luminescent means which emit luminescent light with a deviating from the spectral distribution of the luminescent light (8) of the first luminescent spectral distribution.

23. The method according to any one of the preceding claims 17 to 22, characterized in that the orientation-dependent transmittance (11, 12) and / or reflectivity (11, 12) in the excellent wavelength range (14) spectrally selective with respect to a larger, the excellent wavelength range ( 14) is a comprehensive wavelength range.

24. The method according to any one of the preceding claims 17 to 23, characterized in that the first element (3) is applied by printing technology.

25. The method according to any one of the preceding claims 17 to 24, characterized in that the second element (5) is applied by printing technology, wherein the second element (5) comprises a plurality of optical interference structures, each having an intrinsic preferred orientation and with respect to these preferred orientations in the second element (5) are aligned relative to each other at least as far as possible.

26. The method according to any one of the preceding claims 17 to 25, characterized in that the second element (5) in the form of effect pigments, in particular dielectric multilayer interference effect pigments or metal-dielectric Fabry-Perot effect pigments, liquid crystals, coals of coextruded Materials or combinations thereof is formed, wherein the components of the second element (5) each individually an orientation-dependent Transnission and / or reflectivity as the entire second element (5) show.

27. The method according to any one of the preceding claims 17 to 26, characterized in that the second element (5) in the form of coextruded films, a volume hologram, a Lippmann Bragg structure or combinations thereof is or is introduced.

28. The method according to any one of the preceding claims 17 to 27, characterized in that in the first element (3) a first information is stored.

29. The method according to any one of the preceding claims 17 to 28, characterized in that the first element (3) is transparent in the visible wavelength range.

30. The method according to any one of the preceding claims 17 to 29, characterized in that the second element (5) in each case in a spectral range of the luminescence and in a spectral range of the excitation light under at least one orientation is transparent or partially transparent.

31. The method according to any one of the preceding claims 17 to 30, characterized in that in the second element (5) a second information is stored.

32. The method according to any one of the preceding claims 17 to 31, characterized in that between the first element (3) and the second element (5), a further transparent substrate is arranged.