RU2493969C2 - Gonioluminiscent protective element and method of its production - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to gonioluminiscent material. Protective element comprises first element and second element covering at least partially said first element. Second element faces the of protective element observation side. First element comprises first luminescent means while second element comprises optical interference structure with transmissivity and/or reflectivity dependent upon orientation in isolated wavelength band. Said first and second elements are matched so that observed luminescent light changes at excitation of luminescence of the first luminescent means depending upon observation orientation and/or excitation light incidence direction. In said wavelength band at straightly one orientation or in limited orientation range at least one interference structure varies its transmissivity or reflectivity. Note here that isolated spectral band matches with wavelength band wherein first luminescent means can be excited by irradiation by excitation light.

EFFECT: protective element with high degree of protection against counterfeit.

22 cl, 10 dwg

Description

The invention relates to a gonioluminescent security element, which is preferably made in the form of a document protected from forgery or integrated into it, and also to a method for manufacturing a gonioluminescent security element.

As protective elements, structures and structural units that have at least one security feature are considered. In turn, security features are those that impede or, preferably, make it impossible to imitate, tamper, duplicate or the like. In addition, the security features must enable themselves to be verified so that, for example, their authenticity and / or lack of falsification can be verified.

Along with the authentication of the security element, it can often also be encoded information that, through the security element or security feature, is directly protected from tampering and / or imitation.

Documents protected against forgery are objects that contain at least one security feature. Documents that are protected against forgery can only be mentioned as an example: identity cards, passports, cards in the form of cards, access control certificates, visas, excise stamps, tickets, driver’s licenses, car documents, valuable documents such as banknotes , checks, postage signs, bank cards, credit cards, any chip cards and self-adhesive labels (for example, to protect the product). Such counterfeit documents have at least one security feature, typically many different security features. Already prefabricated security elements made in the form of semi-finished products, such as, for example, a reflective or embossed hologram, can be integrated into a document protected from counterfeiting. However, separate components or elements that together contribute to the formation of a security feature can also be integrated into a document protected from a fake.

Accordingly, in a broader sense, a document protected from forgery is always a security element, since it is a structural unit with at least one security feature.

Many security features and security elements are known in the art. For example, security elements or documents protected against counterfeiting are known in the prior art in which information is printed with the so-called optically variable ink (OVI - Optically Variable Ink). An optically variable ink is characterized in that different color sensations or color stimuli of the printed information are distinguished at different angles of view.

Documents protected from forgery or security elements that contain structures that, due to interference effects, show a dependence on the angle of view are also known in the art. Such protective elements, first of all, include, for example, volume holograms, which, as a rule, have high angle selectivity relative to the restoration of information recorded in the volume hologram. In addition, volume holograms are highly selective for wavelengths relative to regenerative light, with which it is possible to restore the hologram.

From DE 60114156 T2, spectacular pigments are known in which luminescent substances are additionally incorporated. In this case, the disadvantage is the fact that when creating a spectacular pigment, one has to obey "necessities" (layer thickness, refractive index of the core material), and therefore, when capsizing, there is not a sufficient and significant optical effect. If, for example, as described in the patent, a phosphor is introduced as a core region with a low refractive index, then for this, only a layer thickness with typical 400 (+ -200) nm is available, which must be precisely observed. As a result of this, for example, the use of typical phosphors with particle sizes of several microns in diameter is excluded. In addition, typical main crystal lattices for phosphors have a higher refractive index than typical OVI base materials, for example MgF ₂ , as a result of which the color change effect upon capsizing is very limited, and therefore typical basic crystal lattices of the phosphor are unsuitable for creating OVI- materials.

Nevertheless, in spite of the already known number of angle-dependent security features and security elements, there is a need to create new security features and security elements in order to provide security against forgery of documents protected against forgery and protected by an appropriate security feature. First of all, it is desirable to create a simple and reliable verifiable security feature.

Therefore, the invention is based on the technical task of creating a security element that has an angle-dependent security feature that can simply be verified and a method for manufacturing it.

To solve the technical problem, the creation of a gonioluminescent protective element is provided, which contains the first and second element, which at least partially overlap. In this case, the second element faces the viewing of the security element, with which the security element is considered during verification. While the first element contains the first luminescent means, the second element contains at least one interference structure, which in the selected wavelength range has an orientation-dependent transmittance or reflectance that causes a distinguishable change in the luminescent light under consideration when the orientation changes exactly under one orientation angle or in a limited range of orientation angle. The first element and the second element are coordinated with each other so that when viewing the first luminescent means during luminescence excitation, depending on the viewing orientation and / or the direction of irradiation of the exciting light through the second element, an optical change is discernible with a selected orientation or a limited orientation range. This means that for the selected connected wavelength range for exactly the same orientation or the same orientation range, the transmission or reflection changes. To produce such a gonioluminescent security element, the first and second element are arranged relative to each other so that the second element at least partially overlaps the first element and the second element faces the viewing direction. In this case, the coordination of the first element with the second element or vice versa should occur so that the luminescent means in an excited state emit light in the selected wavelength range, or that the selected wavelength range coincides with the wavelength range in which the first luminescent means by means of irradiation with exciting light are excitable for luminescence. In the first case, through a change in the transmission or reflectance, the luminescent light with respect to its intensity in the selected wavelength range changes by the second element depending on the orientation. In contrast, in the second case, depending on the orientation, the excitation of luminescence per se changes. The second element contains at least one interference structure, which, with exactly one orientation or in a limited orientation range, changes its transmission or reflection for at least one wavelength or one wavelength range. This wavelength or this wavelength range corresponds to the above allocated wavelength or the selected wavelength range, which, in turn, corresponds to the radiation wavelength or the radiation wavelength range at which the luminescent medium is lit, or the excitation wavelength or the same range of excitation wavelengths. That is, the interference structure changes its transmission capacity and / or reflectance for light in the selected wavelength range for exactly the same orientation or in exactly the same orientation range. Favorable in the invention is that it creates an angle-dependent protective element, which, as a rule, can be checked by simple visual control using an excitation source for luminescence. Since there is exactly one orientation, or one limited range of orientation, in which the visible or contemplated fluorescent light changes in intensity or spectral composition during a change in orientation, for example, when tipping a document protected from a fake, such a security feature can be reliably verified and untrained or little trained people. The selected orientation is determined by the angle (polar angle) relative to the vertical to the surface. The azimuthal angle, that is, the angle in the plane of the surface between any axis in the plane and the projection of the viewing or irradiation direction into the plane, on the contrary, can be any. When using volume holograms, the range of the azimuthal angle can also be limited. A limited orientation range is defined by a limited angular range for the polar angle of the viewing direction or exposure. At least one interference structure can be formed from several identical components, which, however, independently show the corresponding interference properties that the whole structure has. This means that the components have similar orientation-dependent transmission and / or reflection characteristics.

The sign "change in the transmission capacity and / or reflectivity for light in the selected wavelength range for exactly the same orientation or in exactly the same orientation range" means that when the orientation changes, there is a transition from one bandwidth and / or reflectivity to another, different throughput and / or reflectivity when exactly one orientation or a limited orientation range is achieved.

However, the manifestation of an orientation-dependent change in transmittance or reflection in the selected wavelength range for exactly the same orientation or in a limited orientation range does not in all embodiments mean that a change in the observed luminescent light occurs only when this orientation is exact. Moreover, at least one interference structure can be selected so that the reflection and / or transmission with exactly the same orientation changes, but with a continued change in orientation remains essentially constant. For polar angles measured relative to the vertical that are smaller than the polar angle relative to the selected orientation, the at least one interference element shows, for example, the first transmission and / or reflection characteristics in the selected wavelength range. At polar angles greater than the polar angle, which refers to exactly the same orientation, at least one interference element has deviating transmission and / or reflection characteristics in the selected wavelength range. The change between the throughput and / or reflection characteristics occurs with exactly the same orientation. The same applies to the orientation range, in which the transition between different reflective and transmission characteristics is manifested.

In other embodiments, the transmission characteristics and / or reflection characteristics in the selected wavelength range are the same for all orientations, except for exactly one orientation or in addition to the limited orientation range in which or in which the transmission characteristics and / or reflection characteristics for light in the selected range wavelengths vary.

In addition, the proposed separation of the angle-dependent element from the luminescent element is favorable, that is, the use of two independent elements, due to which both elements can be optimized or selected separately in order to achieve a significant optical effect in interaction.

Due to the separation of the first element and the second element according to the invention, there is significantly greater freedom of choice in the selection and combination of elements. So, phosphors can be applied regardless of their physical and chemical properties (for example, refractive index, particle sizes, main crystal lattice ...); or, for example, both organic and inorganic phosphors.

At least one interference structure that is used for the second element has respectively one preferred direction.

In order to enable visual inspection by a human in this way, in one preferred embodiment of the invention, it is provided that the selected wavelength range is in the visible wavelength range. In this case, the second element is preferably made so that relative to the irradiation of the exciting light through the second element, the orientation-dependent influence on the transmission or reflection does not occur. In this case, it is possible to observe the security feature according to the invention in a simple manner in which the security element is viewed from different angles.

In order to be able to reliably distinguish between an orientation-dependent change, in one preferred embodiment it is provided that an orientation-dependent change in throughput and / or reflectance of more than 30%, preferably more than 50%, and most preferably more than by 80%. An orientation-dependent change is particularly distinguishable if the element contains at least two (side) adjacent regions, of which at least one of the at least two regions does not overlap or is not overlapped by the second element. An orientation-dependent change in distinguishable luminescence occurs when the orientation changes only in that region or regions of the first element that are overlapped by the second element. Since, for example, the human eye is well adapted to clearly distinguish between relative differences in color tone and / or intensity, an orientation-dependent change in perception in this embodiment is particularly easy to detect.

The first element may contain first luminescent means that have a narrow-band or broad-band luminescence spectrum. As a rule, the first luminescent means will contain a narrow-band luminescence spectrum with one or more spectral lines located adjacent or at a distance from each other in the wavelength spectrum. The coordination of the first element, i.e., the first luminescent means, with the second element, i.e., the selected wavelength range, in which the orientation-dependent change in reflectivity and / or throughput occurs, occurs in embodiments in which, depending on the orientation, the spectrum is influenced luminescence so that the first luminescent means emits luminescent light in the selected wavelength range, preferably has a maximum luminescence of the first luminescent medium STV.

In order to establish, first of all, a certain color of luminescence, it is favorable to add additional luminescent agents to the first element. They have a spectral distribution deviating from the spectral distribution of the first luminescent agent. In order, for example, to make a color change that can be perceived by an observer and without the comparative area of the first element not overlapping by the second element, it is advantageous if the second element is designed such that the orientation-dependent bandwidth and / or reflectivity in the selected wavelength range is spectrally selective relative to a larger containing a selected wavelength range of the wavelength range. A spectrally selective dependence on orientation means that the change in transmission and / or reflection appears only in a limited range of wavelengths, here in a distinguished range of wavelengths. This means that the change in reflectivity or throughput varies only in the selected wavelength range depending on the orientation. In contrast, no change is observed in the adjacent spectral region or wavelength range, or only a very much smaller change in transmission and / or reflectance is observed. In luminescent light, which is broadband and / or consists of several spectral lines, which are not all in the selected wavelength range, this leads to the fact that only for part of the spectral lines or the spectral region or wavelength range of luminescent light orientation changing bandwidth and / or reflectivity. Due to this, the color impression changes depending on the orientation, so the color impression that a person distinguishes when looking at fluorescent light, as a result of color addition, depends on the spectral composition of the fluorescent light. If only a part of the spectrum is transmitted or reflected by the second element, this leads to a change in the spectral composition of the distinguishable spectral distribution and, through this, to a color change.

In one preferred embodiment, it is provided that information is recorded in the security element. This may be, for example, individualizing and / or personalizing information. Such information is considered as individualizing, which provides the possibility of distinguishing a security feature from another security feature of the same kind. The individualizing information may be, for example, a serial number. As personalizing information, such information is considered that contains information about the person to whom the security element was written. If a security element is integrated, for example, into a document used as a passport, the name, date of birth, biometric data encoded in the security element, for example, a face image, fingerprints, etc., can be used as personalizing information. Individualization and / or personalization, first of all, is possible both by planar structuring of the first element, and by planar structuring of the second element and / or structuring of the overlap area. Thus, preferred embodiments provide that the first information is recorded in the first element and / or the second information is recorded in the second element. In this regard, the use of the concepts of “first” and “second” information does not constitute prioritization of information.

As the first and / or additional luminescent agents, all substances and agents excitable for luminescence known to those skilled in the art can be used. Preferably, luminescent agents that exhibit fluorescence or phosphorescence are used. In the case of luminescence, we can talk about photoluminescence, electroluminescence, including light emission by organic or inorganic LEDs, or about radioluminescence. Luminescent agents that are transparent in the visible wavelength range are preferred, so that the first element is transparent in the visible wavelength range. Due to this, it can be achieved that, if possible, on the object that is equipped with a protective element, a printed layer or a printed layer, which in the protective element is applied when viewed from the side of the gaze under the first element, does not deteriorate with respect to perception until luminescence is excited. In addition, luminescent agents may also be contained in visible printing ink (pigment).

The second element, respectively, in one spectral region of the luminescence, as well as in one spectral region of the exciting light in at least one orientation, is transparent or partially transparent.

The second element may contain one or more optical interference structures. Multilayer interference structures turned out to be suitable interference structures. For example, coextruded films can be used that are selected so that they have high bandwidth below the allocated wavelength and low bandwidth above the allocated wavelength. The same can be realized for reflectivity. It is also possible, below the allocated wavelength, to have a low bandwidth, and above a high bandwidth or, accordingly, reflectivity. Such structures are known to the skilled person as the so-called low-pass filters or high-pass filters. These structures have such a property that at the selected wavelength, the throughput and / or reflectance changes when the layers are viewed vertically. If the orientation relative to the vertical viewing is changed, the selected wavelength is shifted towards shorter wavelengths. The range in which this selected wavelength shifts when the orientation changes determines the selected wavelength range of the interference element.

The so-called effect pigments exhibit a similar behavior, first of all, electric multilayer interference effect pigments, which contain several, for example, dielectric layers deposited or deposited on mica particles, or metal-dielectric Fabry-Perot pigments, in which the dielectric particle is coated with partially permeable metal in layers. Effective pigments are made so that they have their own preferred orientation. This means that they have a preferred direction, which, for example, is equivalent to the vertical in coextruded films. In the manufacture of spectacular pigments, the initial particles are selected so that they have a greater planar extent along one plane than in all other possible orientations in space. In the formation of the second element, several interference structures of the same or different type can be applied, however, however, they are oriented accordingly with respect to their own preferred orientation relative to each other at least to the greatest extent possible. Along with high-pass filters and low-pass filters, of course, band-pass filters are also applicable, which pass or block only one specific wavelength range, which is also shifted during rollover. Other possible interference patterns can be made, for example, by means of liquid crystals. Volumetric holograms or Lippmann-Bragg structures can also be favorably applied. Volumetric holograms give, for example, the advantage that complex information can be recorded in them, regardless of plane structuring during production, which can be read during restoration. In the security element according to the invention, restoration occurs only when the angle of view coincides with the angle of restoration determined during manufacture. In addition, various information for different spectral lines can be recorded in the volume hologram, which, in addition, can be reconstructed at different viewing angles and lighting angles. However, it is essential that the volume hologram is configured such that an orientation-dependent change in transmittance and / or reflection appears for a certain range of wavelengths in the same orientation or in the orientation range.

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

The individualization and / or personalization of the security element is particularly simple, since at least the first element is preferably made using printing techniques. Luminescent products simply integrate into printing inks and / or printing inks.

In one particularly preferred embodiment, a second element is also manufactured using a printing technique. First of all, the said effective pigments, but also liquid crystals that form the cholesteric phase or flakes of coextruded materials (for example, coextruded films or glasses) can be applied using a printing technique. In this case, it is used that the intrinsic orientation of at least spectacular pigments and flakes, which have a preferred direction, is accompanied by a geometric shape, so that geometric construction on the surface causes individual interference structures to be oriented together relative to each other and the first element, or viewing directions. However, it is important that formed from several components, which also contain all interference structures, the interference structure has a preferred direction with respect to only one spatial direction (vertical to the surface). Only in this way is it ensured that a change in transmittance and / or a change in reflection appears for the selected wavelength range only with exactly the same orientation, that is, with a polar angle relative to the vertical.

If a volume hologram or coextruded films are used as an interference structure, then it is possible to apply them to a finished valuable document, while the valuable document contains luminescent substances as the first element, and the optical effect according to the invention is manifested in the interaction. If a volume hologram or co-extruded films are used as an interference structure, it is possible to print the first element on a holographic recording medium of a volume hologram or on co-extruded films, the print side being the side of the second element respectively facing away from the viewing side of the security element. In other embodiments, the first element is preferably applied using a printing technique to a substrate. In the case of the substrate, we can talk about any substrate layer known to the specialist, especially on a plastic basis, textile basis and / or paper basis. Examples of plastics are representatives of the group comprising PC (polycarbonate, primarily bisphenol-A-polycarbonate), PET (polyethylene glycol terephthalate), PMMA (polymethyl methacrylate), TPU (thermoplastic polyurethane elastomers), PE (polyethylene), PP (polypropylene), PI ( polyimide or polytransisoprene), ABS (acrylonitrile-butadiene-styrene), PVC (polyvinyl chloride) and copolymers of such polymers. The second element can be printed or applied directly to the substrate with the first element printed on it. Application can take place, for example, by means of adhesives that act thermally and / or in a UV-structuring manner. Alternatively, lamination can take place, in which both elements or the layers between them under pressure and temperature are coupled in an adhesive manner. It is also possible between the first element and the second element to arrange transparent substrate layers, which, in the wavelength range of the exciting light and fluorescent light, are transparent or at least partially transparent or luminescent.

A particular advantage with a suitable choice of interference structures is that the protective element can be applied to almost any substrate using printing equipment and methods. Moreover, it is simply possible to store and protect information in the security element, first of all, individualizing and / or personalizing information.

Also possible are embodiments that comprise a third element, which also contains at least one interference structure and partially overlaps the first element. Due to this, protective elements can be created which, for example, provide an orientation-dependent inverse color change in different areas of the security element at the same time, that is, when the orientation is changed.

The invention is further explained in more detail with reference to the drawings:

Figa: a schematic sectional view of a security element;

Fig.1b: a schematic top view of the protective element according to figa;

Fig. 2a: a schematic sectional view of the security element according to Fig. 1 when excited by UV radiation and viewed vertically;

Fig.2b: a top view of the protective element according to figa;

Figa: a schematic sectional view of the protective element according to Fig.1 when excited by UV radiation and viewed in an orientation deviating from vertical viewing;

Fig.3b: top view of the protective element according to figa;

Figure 4: a graphical representation of the reflectance / throughput plotted in relation to the wavelength depending on different viewing angles; and

5a-5c: a schematic top view of another security element when viewed vertically without excitation of luminescence (a), when viewed vertically with excitation of luminescence (6) and viewed in a deviating orientation when excited by luminescence.

1, a protective element 1 is schematically depicted. A first element 3 is deposited, preferably printed, on a substrate 2. The first element 3 contains one or more luminescent means that exhibit luminescence in the visible wavelength range after excitation or when excited by short-wave light, for example, UV wavelength range. The application of luminescent agents can occur, for example, by the method of letterpress, intaglio printing, screen printing, digital printing or flat printing, especially offset printing, which can be a method of wet offset printing, anhydrous offset printing or dry offset printing. For individualizing or personalizing printing, for example, an inkjet printing method is suitable. Above the first element 3, there is a second element 5 facing towards the viewing direction 4 of the protective element 1, which at least partially overlaps the first element 3. The second element 5 contains one or more interference structures. In the case of interference structures, we can speak, for example, of coextruded films. The interference structures can also be multilayer interference effect pigments from dielectric layers or metal-dielectric effect pigments Fabry-Perot or liquid crystals that form the cholesteric phase, or combinations thereof. The interference patterns indicated by the latter are most easily applied by printing, such as screen printing. However, any other printing methods can also be applied if the interference patterns are printed so that they are oriented relative to the first element so that the proper orientation with respect to the orientation-dependent interference property for all interference patterns is identical or almost identical. If, for example, dielectric multilayer interference effect pigments are used, they have a transparent core, for example a mica particle, which is coated with several dielectric layers. A mica particle has a planar extent in one spatial plane, which is greater than in all other possible spatial directions. This means that the dielectric multilayer interference effect pigment has a flattened shape. When printing such dielectric multilayer interference effect pigments, they are oriented so that they are arranged with their flat side essentially parallel to the substrate or the flat surface of the first element or located between the first element and the second element of the substrate layer. A single orientation of several dielectric multilayer interference effect pigments is necessary, so that orientation-dependent, i.e., angle-dependent, interference effect appears macroscopically, which leads to an optically distinguishable change in the security element, as explained in more detail below. The same applies to flakes of coextruded materials, which have a geometric shape that is adapted to the preferred direction of interference properties. That is, the preferred geometric direction is determined relative to the preferred direction of interference. Flakes of coextruded materials have, for example, a flat shape. The normal to a certain flat surface shape coincides, for example, with a vertical relative to which the direction-dependent reflective and / or throughput of the coextruded material is determined. In other embodiments, the security element 1 may comprise additional layers, and itself is preferably made as a security document, such as a passport or identification document, or as a valuable document or the like. In the present embodiment, under the substrate layer 2 is a clutch enhancer layer 6, so that the security element 1 can be applied to other documents and / or objects protected from counterfeiting, for example, by hot stamping. Other possibilities for the development of the adhesion promoter layer are, for example, the adhesive described in DE 102006048464 A1, which in the first stage can be dried by UV curing, as a result of which the element can be placed in a roller form without blocking, and in the second stage, for example lamination process, thermally connected to the substrate below. Alternatively, this adhesive, of course, can, if necessary, be printed or coated on a substrate on a partial surface, so that later, when laminating, it adheres to an adhesiveless security element. Another example is the method described in DE 102007052949 A1, in which an element or substrate is coated with a mixture of a solvent or solvents and a geminally substituted dihydroxydiphenylcycloalkane derivative of a polycarbonate, dried, and then, for example, by lamination, adheres to another layer.

One skilled in the art will understand that both the first element and the second element can easily record the first and second information. First of all, this refers to the case if the elements are made using the printing technique. When printing, for example, it is possible to perform almost any planar structuring of the first element and the second element and thereby encode information, for example, in the form of alphanumeric characters and / or graphic characters and / or images. If coextruded films are used as interference structures, they can also be planarly structured, for example by die-cutting or the like. If a volume hologram is used as an interference element, then, as is known to a person skilled in the art, a volume hologram can contain information that can be read from it only when the hologram is restored under a given restoration geometry, which contains the direction of incidence of the restoring light and the viewing direction.

The luminescent means that the first element contains are preferably made so that they are transparent in the visible wavelength range. Also, the second element is also made so that it is at least in the partial range of the visible wavelength spectrum is transparent or partially transparent. Due to this, first of all, it is possible that the information recorded in the substrate 2, which is deposited, for example, by means of a conventional printing layer (not shown), is visible to the viewer until the luminescence of the first element is excited.

In order to check and / or verify the protective element 1, the protective element is irradiated with exciting light 7. This is light in the ultraviolet wavelength range, which is tuned to the luminescent means of the first element 3 so that it leads to luminescence of these luminescent means. On figa presents this situation for the protective element 1 according to figa. Solid arrows indicate luminescent light 8, which the beholder distinguishes in a vertical view from above on the protective element 1. However, the exciting light 7 can, for example, also be in the visible wavelength range (the so-called fluorescence of daylight). Also, when excited in the infrared wavelength range, it is possible to emit, for example, light visible with the help of anti-Stokes properties.

Fig. 3a shows a situation in which the protective element 1 is also irradiated with exciting light 7, so that luminescent light 8 is generated in the first element. However, luminescent light 8 is now shown, which the beholder distinguishes with a different, deviating from vertical, orientation. At least a portion of the luminescent light 8 ′ is reflected in the second element 5, that is, in the interference structure or interference structures. This means that the throughput of the interference structure or interference structures of the second element 5 decreases when the orientation is changed.

Schematically, the throughput / reflectivity of the interference element is shown in Fig.4. There, the throughput (reflectance) is shown with respect to the wavelength for vertical viewing 11 (solid line) and for viewing at an angle of 60 ° 12 relative to the vertical to the surface (dashed line). At a selected wavelength of 13, there is an abrupt change in throughput (reflectivity) when viewed vertically. When capsizing, this distinguished wavelength 13 ′, at which an abrupt change in transmission (reflection) occurs, shifts toward shorter wavelengths. The wavelength range in which the bandwidth (reflectivity) changes is also called the allocated range of 14 wavelengths or the selected spectral region. In order for the optically distinguishable effect to occur when the protective element is tilted during luminescence excitation, the luminescent means of the first element must be matched with the interference structures of the second element so that significant emission of luminescent light occurs in this selected spectral region or 14 wavelength range. If the luminescence spectrum of the first element has a linear spectrum, then preferably one of the spectral lines of the luminescence spectrum is in a selected spectral region or a range of 14 wavelengths.

In the embodiment shown in FIGS. 1a-3a, it is assumed that the first element, that is, one or more interference structures of the first element, has a reflectivity that increases when capsizing in the wavelength range of the luminescent radiation 8, or a bandwidth that decreases . As the skilled person knows, various interference structures can be formed which behave in the opposite way, which means strong transmittance (weak reflection) at short wavelengths and weak transmittance (strong reflection) at long wavelengths. Of course, bandpass filters can be generated similarly.

On figb-3b presents schematic views of the protective element 1 according figa-3a, which in each case correspond to each other. On figb it is seen that the second element 5 overlaps the first element 3 only partially and, in addition, is structured so that it could be interpreted as a bar code. In the form according to figb luminescence is not excited.

FIG. 2b is a vertical top view of a security element in which luminescence of the luminescent means of the first element 3 is excited. Emission of luminescent light is indicated by hatching. The thickness of the hatching strokes indicates the intensity of the distinguished luminescent light. It is clearly seen that in the entire area of the planar extent of the first element 3, strong luminescence is distinguishable.

On figb given a top view in deviating from a vertical viewing orientation when exciting luminescence. It is seen that in the overlapped regions 9, in which the second element 5 partially overlaps the first element 3, a noticeable decrease in luminescence occurred. As a result of this, the structure of the second element 5 is distinguishable looking like a shaded area, which corresponds to the overlapped region 9, which in the top view according to fig.2b was invisible, since the second element 5 is transparent there.

5a-5c are schematic top views of another embodiment of the security element 1. In the embodiment shown, information is encoded in the first element 3, which in this case is schematically represented as A. The second element is made 5 so that it covers only part , half 15, of the first element 3.

In the view of FIG. 5 a, in which luminescence is not excited, the information of the first element 3 is indistinguishable since the luminescent means of the first element 3 in the visible wavelength range are transparent.

On figb presents a situation in which the luminescence of the luminescent means of the first element 3. is excited. The protective element 1 is viewed in a vertical view from above. The luminescence is clearly visible in the entire region of the first element 3. Thus, in this form, the information recorded in the first element 3 is clearly distinguishable.

FIG. 5c is a view of a security element 1 in which the security element 1 is viewed in a deflected orientation. The interference structure or interference structures of the second element 5 in the luminescence region in this orientation have almost no transmission. Therefore, by means of the emitted luminescent radiation, only the uncoated half 16 of the letter A is distinguishable. Thus, a strong contrast arises for the user, so that the security element can simply be verified.

The described embodiments are merely exemplary, very simplified options. One skilled in the art will appreciate that significantly more complex embodiments are possible. First of all, additional elements can be applied that have interference structures, which, for example, have opposite transmission / reflection characteristics relative to the second element and overlap other parts of the first information.

If the luminescent means contained in the first element emit luminescent light in a large spectral region or in the form of several spectral lines far apart from each other in the spectrum of wavelengths, then a change in reflectivity or bandwidth depending on the angle of view or on the tip will only lead to spectrally selective change. This means that only the luminescent light in a limited spectral region is affected by the change in reflectance / bandwidth. However, with the appropriate choice of luminescent agents, this leads to the fact that there is a clearly distinguishable color change during capsizing. If the second element does not overlap the entire first element, then, of course, a color change occurs only in part of the first element when capsizing. Thus, in this case as well, the security element can simply be verified due to the fact that in the partial area of the first element there is a clearly distinguishable color change.

The first information may be recorded in the first element and in a “color image”. First of all, if the first element contains several different luminescent means, some of the information can be produced using the first luminescent means, which emits luminescent light, which causes the first color impression. By using one or more other luminescent means that emit luminescent light of deviating color impressions, other information or background can be produced. Since the second element has a spectrally selective dependence of the bandwidth / reflectivity on orientation in the selected wavelength range, with the appropriate choice of luminescent means, the effect is only on the luminescent light of the first luminescent means, for example, it is reflected. The views shown in FIGS. 2a and 3a in this embodiment can also be interpreted so that the fluorescent light 8 has different wavelengths. While in a vertical top view (cf. FIG. 2a), luminescent light 8 of both wavelengths is transmitted, in the tilted state (FIG. 3a) only luminescent light 8 of the same wavelength is transmitted, and the rest of the luminescent light 8 ', on the contrary, is reflected in the second element 5.

Particularly preferably, the described security elements are designed as counterfeit and / or valuable documents that contain additional security features and / or security elements. Alternatively, security elements may be integrated into a counterfeit and / or security document.

One skilled in the art will recognize that there are many other possible implementation options for such a security element.

As examples, embodiments have been explained in more detail in which the first element and the second element are preferably applied using a printing technique. In other embodiments, the first element may also be integrated into the substrate or itself be the substrate on which the second element is applied. For example, luminescent agents can be integrated into a substrate, for example a plastic film.

It is also possible to incorporate luminescent agents in the form of mixed fibers or tablets into the substrate. For the introduction of such elements, paper is primarily suitable.

In addition, if the paper has a surface structure, for example in the form of a tangible watermark, the second element deposited on it adapts to this surface structure. Thus, the angular selectivity of the second element in the verification of the sign will follow the shape of the surface structure. Thus, the surface structure upon excitation of luminescence becomes visible in reflected light.

In addition, any suitable surface relief is reproduced in the security feature according to the invention. Surface reliefs can occur, for example, by embossing a substrate by metallographic printing or by lamination, for example using structured laminating plates.

In the case of documents made in the form of plastic cards and / or protected against counterfeiting, the production typically takes the form of a laminate. A typical method of manufacturing such a valuable and / or tamperproof document for incorporating the described security element involves the following:

1) preparation of substrate layers from these plastics, typically in a thickness of 10 μm to 1000 μm, preferably 50 μm to 250 μm. The layers of the substrate can be printed, they can be transparent, translucent, opaque, adapted for laser engraving, etc. Inlay layers of a contactless chip and antenna may also be used. One or all layers of the substrate may also have an adhesive layer. Layers of the substrate do not have to all consist of the same material.

2) on one of the layers of the substrate is applied, preferably printed, the first element.

3) on this substrate layer with printing, or on another substrate layer, for example, a substrate layer made in the form of a transparent film, one of the methods described above is applied to the second element. In the case of applying on another layer of the substrate, this stage in time, of course, does not have to occur after printing.

4) the layer (s) of the substrate with the first and second element are brought into contact with other layers of the substrate and are laminated under the influence of pressure and temperature. In this case, a strong bond is formed between the individual layers of the substrate, which is also called a laminate.

5) then the laminate is further processed, for example with respect to its contour shape, by punching. In the manufacture with repeated use, separation occurs, for example, also by punching. If necessary, prior to punching or after punching, a protective film, such as a diffractive protective film, may be applied. Can also be applied a layer of protection against scratches, for example in the form of varnish. A combination of a scratch protection layer and a protective film may also be used.

A special case is the subsequent application of the second element in step 5. In this case, the second element is not laminated to the card body, but glued to it. This can be advantageous, first of all, if the second element is individualized or personalized. For example, a volume hologram can be applied to a part of the surface or to the entire surface, and part of it as a second element in the sense of the invention interacts with a luminescent element located below.

In other embodiments, in which, for example, a volume hologram is illuminated in a holographic recording medium, the first element can be applied using a printing technique on the side of the holographic recording medium facing away from the viewing side. Preferably, the volume hologram is not illuminated over the entire surface of the film, so that in this case are also possible embodiments in which the second element (volume hologram) covers only part of the first element.

Similarly, a security element can be made using coextruded films. For example, the substrate with the first luminescent means printed on it, for example paper, is provided with a second element from a coextruded film by means of a deposition process (for example, by hot stamping), so that a gonioluminescent effect according to the invention is obtained. It is also advantageous if the coextruded film applied by hot stamping has additional protective features, for example, it is a carrier of diffractive (partially) metallized surface embossing, and thus, under normal illumination by reflected light, it has typical optical effects of embossed holograms (as, for example, Kinegram shows them ®) and under UV illumination in combination with the first luminescent element below the gonioluminescent effect.

For the implementation of the invention, the described elements and features can be applied in any combination.

Reference List

1 security element

2 substrate

3 first element

4 side viewing

5 second element

6 layer clutch booster

7 exciting light

8, 8 ′ fluorescent light

9 overlapped area

11 throughput / reflectivity at 0 °

12 throughput / reflectivity at 60 °

13, 13 ′ selected wavelength

14 selected wavelength range / spectral region

15 overlapped half

16 uncovered half

Claims (22)

1. Gonioluminescent protective element (1) containing the first element (3) and at least partially overlapping the first element (3), the second element (5), the second element (5) facing the side (4) of the viewing of the protective element (1) ),
the first element (3) contains the first luminescent means, and the second element (5) contains at least one optical interference structure, which in the selected wavelength range (14) has an orientation-dependent transmission capacity (11, 12) and / or reflectivity (11, 12),
wherein the first element (3) and the second element (5) are matched to each other so that when viewing the first luminescent means during luminescence excitation, depending on the viewing orientation and / or the direction of incidence of the exciting light through the second element (5), the optical a change in the fluorescent light in question,
at the same time, in the selected wavelength range for exactly one orientation or in a limited orientation range, at least one interference structure changes its throughput and / or reflectance, characterized in that the selected spectral region (14) coincides with the wavelength range in which the first luminescent means by means of irradiation with exciting light (7) are excitable for luminescence. 2. Gonioluminescent protective element (1) according to claim 1, characterized in that the selected wavelength range (14) is in the visible wavelength range. 3. Gonioluminescent security element (1) according to claim 1, characterized in that in the selected wavelength range (14), an orientation-dependent change in throughput (11, 12) and / or reflectivity (11, 12) is more than 30%, preferably more than 50%, most preferably more than 80%. 4. Gonioluminescent protective element (1) according to one of claims 1 to 3, characterized in that the first element (3) along with the first luminescent means contains additional luminescent means that emit luminescent light with a spectral distribution deviating from the spectral distribution of luminescent light (8) the first luminescent products. 5. Gonioluminescent protective element (1) according to one of claims 1 to 3, characterized in that the orientation-dependent bandwidth (11, 12) and / or reflectivity (11, 12) in the selected wavelength range (14) is spectrally selective with respect to a larger wavelength range spanning the selected (14) wavelength range. 6. Gonioluminescent security element (1) according to claim 1, characterized in that the second element (5) contains several optical interference structures, which respectively have their own preferred orientation and with respect to these preferred orientations are at least as possible oriented relative to each other in the second element (5). 7. Gonioluminescent protective element (1) according to one of claims 1 to 3 and 6, characterized in that one or more optical interference structures contain one or more effective pigments, especially dielectric multilayer interference effect pigments or metal-dielectric effect pigments Fabry - Pen, coextruded materials (films, glass) in the form of flakes or in the form of overlays or films having a large area, volume holograms, liquid crystals, Lippmann-Bragg structures, or combinations thereof. 8. Gonioluminescent protective element (1) according to one of claims 1 to 3, characterized in that the first information is recorded in the first element (3). 9. Gonioluminescent protective element (1) according to claim 1, characterized in that the first element (3) in the visible wavelength range is transparent. 10. Gonioluminescent protective element (1) according to one of claims 1 to 3, 6 or 9, characterized in that the second element (5), respectively, in one spectral region of luminescence, as well as in one spectral region of the exciting light (7) at least at least in one orientation it is transparent or partially transparent. 11. Gonioluminescent protective element (1) according to one of claims 1 to 3, 6 or 9, characterized in that the second information is recorded in the second element (5). 12. Gonioluminescent protective element (1) according to claim 1, characterized in that the first element (3) is applied to the substrate (2), and the second element (5) is applied to the first element (3) or to the substrate (2). 13. Gonioluminescent protective element (1) according to one of claims 1 and 12, characterized in that between the first element (3) and the second element (5) is another transparent substrate. 14. Gonioluminescent security element (1) according to one of the preceding claims 1 to 3, 6, 9 or 12, characterized in that the security element (1) is made in the form of a document protected from forgery. 15. A method of manufacturing a gonioluminescent security element (1), in which the first element (3) and the second element (5) are positioned relative to each other so that the second element (5) is at least partially superimposed on the first element, and the second element (5 ) facing the viewing side,
the first element (3) contains the first luminescent means, and the second element (5) contains at least one interference structure, which in the selected wavelength range (14) has an orientation-dependent transmission capacity (11, 12) and / or reflective ability (11, 12),
wherein the first element (3) and the second element agree with each other so that when viewing the first luminescent means during luminescence excitation, depending on the viewing orientation and / or the direction of incidence of the exciting light (7), the optical element is distinguishable through the second element (5) change, at the same time form at least one interference structure so that it in its selected wavelength range for exactly the same orientation or in a limited orientation range changes its throughput and / or and reflectivity, characterized in that
the first element (3) and the second element (5) agree with each other so that the selected spectral region (14) coincides with the wavelength range in which the first luminescent means are excited to luminescence by irradiation with exciting light (8). 16. The method according to p. 15, characterized in that the selected range (14) of wavelengths is in the visible range of wavelengths. 17. The method according to p. 15, characterized in that the second element (5) is performed so that an orientation-dependent change in throughput (11, 12) and / or reflectivity (11, 12) in the selected range (14) is achievable wavelengths of more than 30%, preferably more than 50%, most preferably more than 80%. 18. The method according to one of the preceding claims 15-17, characterized in that the first element (3) along with the first luminescent means contains additional luminescent means that emit luminescent light with a spectral deviation from the spectral distribution of luminescent light (8) of the first luminescent means distribution. 19. The method according to one of the preceding claims 15-17, characterized in that the orientation-dependent bandwidth (11, 12) and / or reflectivity (11, 12) in the selected wavelength range (14) is spectrally selective with respect to a larger covering the selected range (14) wavelengths of the wavelength range. 20. The method according to p. 15, characterized in that the first element (3) is applied using the printing technique. 21. The method according to p. 15, characterized in that the second element (5) is applied using the printing technique, while the second element (5) contains several optical interference structures, which respectively have their own preferred orientation and with respect to these preferred orientations in as far as possible oriented in the second element (5) relative to each other. 22. The method according to p. 15 or 21, characterized in that the second element (5) is made in the form of effective pigments, primarily dielectric multilayer interference effect pigments or metal-dielectric effect pigments Fabry-Perot, liquid crystals, flakes of coextruded materials or their combinations, while the components of the second element (5) respectively separately show the orientation-dependent transmission and / or reflectivity, as the entire second element (5), or the second element (5) is applied or introduced in the form of coextra films, volume holograms, Lippmann-Bragg structures, or combinations thereof.

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