EP3150763A1

EP3150763A1 - Product containing a carrier with protective markings, and method for determining the authenticity of a product

Info

Publication number: EP3150763A1
Application number: EP15803898.4A
Authority: EP
Inventors: Arkadiy Vladimirovich Trachuk; Andrey Borisovich Kuryatnikov; Igor Vasilievich Pavlov; Alexandr Igorevich MOCHALOV; Alexey Vitalievich Salunin; Georgiy Valentinovich KORNILOV; Alexandr Mikhailovich SHIRIMOV; Anatoliy Pavlovich Gubarev; Viktor Andreevich VOROBIEV; Oshir Yaizgilovich Manashirov
Original assignee: Aktsionernoe Obshchestvo "goznak"
Current assignee: Aktsionernoe Obshchestvo "goznak"
Priority date: 2014-06-02
Filing date: 2015-05-28
Publication date: 2017-04-05
Also published as: EP3150763A4; WO2015187060A1; RU2561073C1

Abstract

The invention relates to protection of products against counterfeit and is intended for instrumental authentication of printed security products such as banknotes and forms of security papers, labels, excise and postage stamps, payment and identity documents, as well as passport and travel documents.

The object of the invention is to provide a product comprising a security marking based on a composite material having a specified combination of magnetic and optical properties, where optical properties are temperature dependent and magnetic properties provide induction heating of the material only in the presence of an alternating magnetic field having predetermined parameters.

The present technical solutions and authentication methods ensure a high level of protection of a valuable document against counterfeit.

Description

Field of the Invention

The invention relates to protection of products against counterfeit and is intended for instrumental authentication of various printed security products, such as banknotes and forms of security papers, labels, excise and postage stamps, payment and identity documents, as well as passports and travel documents.

Prior Art

Recently, as the competition among manufacturers of printed security products is increasing and technical capabilities of potential counterfeiters are steadily growing, complex security features become even more important. The security features are generally understood as technical solutions, which comprise checking, in instrumental authentication, not one, but two or more parameters related in a predetermined way, or defining a predetermined response to two or more simultaneous effects.
In this context, complex effect refers to the effect of two dissimilar fields, for example, a magnetic field having a predetermined intensity and frequency, and an optical field - pumping (exciting) radiation.
Such complex effects include e.g. the dependence of UV luminescence of a substance on the temperature applied to it, or the angle of rotation of the polarization plane of a linearly polarized radiation when exposed to an external electric field, or the reversible change of color of the substance caused by heat and light.
On the other hand, one of the most effective and technically viable solutions for authentication of banknotes and valuable documents is the use of striking and unusual ("Strike & Attractive") visual security features based on various visual effects. Advantages of this approach include the ease of determining the authenticity by people and cashiers, high efficiency of control and high security level achieved.
The visual effects typically include the effect of motion of a graphical object, the effect of changing the shape and size of the object, the effect of changing its color, the effect of pulsation or dynamic change in brightness, or the effect of volume (stereoscopy).
In some cases, simple and inexpensive devices, called visualizers, can be used to observe these visual effects. Various UV lamps, IR visualizers, polarizing filters, etc. may be referred to the visualizers.
Owing to the above advantages, the observable and, in particular, machine-readable security features find very wide application in protection against counterfeit, especially for authentication in bank and cash services.
A problem of provision such features is often in that the interesting parameters of a feature must be reliably estimated under dissimilar effects within a limited time interval, or at a low content of the substance being measured and simultaneous disturbing factors (noise), that is, at a low signal-to-noise ratio, and at insufficient speed of the processes (inertia) which makes high speed authentication more difficult.
On the other hand, to make chemical and/or elemental control of substances included in the security marking more difficult, their amount (percentage) in the overall composition must be minimized. Moreover, it is frequently required that the security features for instrumental and machine authentication should be hidden, that is, cannot be detected by publicly available methods. In this regard, solutions that are of practical interest for creation of complex security features are primarily those that do not manifest their properties in the visible light range, which significantly complicates solution of the problem.
These contradictions and a wide range of publicly accessible substances known from the prior art and available on the market dictate the need for search and creation of new security features with a complex principle of action.
The present invention is based on the combined use of such known physical phenomena as induction heating, disappearance of magnetic properties of materials at a temperature above the Curie point, and thermal quenching of luminescence.
The invention is based on the use of a material comprising a binder and particles of an inorganic compound capable of being heated when exposed to an external alternating magnetic field due to losses for magnetic reversal, eddy currents or relaxation, and also capable of reversibly changing optical properties with temperature. The material can also be a composite material containing particles of an inorganic substance possessing the aforementioned magnetic properties and particles of a substance capable of changing optical properties with temperature, with the mutual arrangement of the particles providing efficient heat transfer between them.
Visual effect may lie in the fact that when a valuable document is observed in a special visualizer, which provides optical pumping (excitation) of the composite material and simultaneous exposure to an alternating magnetic field having a given power and frequency, a visual dynamic change in the brightness of the security marking can be seen.
The object of creating a complex security feature (double-action feature) is attained by the use of a composite material possessing a specified combination of magnetic and optical properties, where optical properties are temperature dependent, and magnetic properties provide induction heating of the material only in the presence of an alternating magnetic field having specified parameters.
The object of the invention is to enhance the level of security, to enable visual, expert or machine authentication of a product based on the use of a security feature having a complex principle of action.
Also of particular interest in instrumental authentication of valuable documents are technical solutions that may use certain information about the document being checked, and that are not only inaccessible to a potential counterfeiter, but hidden from people either.
In a case of applying on the security marking of some deliberate information, this information should be preserved at least during the authentication time and maximum during the circulation period of the product. In this regard, most promising is the application of security information that has a local time nature. For example, information can be applied on a product for use within a short period of time, i.e. applied and preserved on the product only during the cycle of its authentication in a counting-sorting or cash machine. After the authentication the information may disappear in a natural way, for example, disintegrate under the effect of environmental components (temperature, humidity, pressure, magnetic fields, light, etc.).
Security of a document can be enhanced according to the present invention preferably owing to the use in the structure or on the surface of a valuable document of a security marking including a composite material that changes its temperature when exposed to an external alternating magnetic field, and simultaneously possesses a luminescence, which is manifested under an exciting radiation, parameters of the luminescent glow being temperature dependent.
A prior art solution describes a combination of security features for valuable documents, which comprises two fluorescent substances, one of the substances irreversibly losing its properties at a temperature exceeding the combustion temperature of the document. This solution uses the principle of complex effect on the document, including temperature and luminescence. Authenticity of the document is determined on the basis of luminescence analysis after the effect of a temperature equal to the combustion temperature of the document. According to the inventors, this solution enables authentication of a valuable document even if it was previously destroyed by incineration ( RU 2249504 ).
A conventional method of determining the validity of a valuable document comprises heating the surface of a document containing a marking with magnetic properties. Heating is performed to a temperature exceeding the temperature of the Curie point of the magnetic material used, and visual detection of a change in the document image is performed by viewing the document through a special magnetic field sensitive transparent sheet ( US 5533759 ).
This prior art does not provide for automatic (machine) authentication of a valuable document. Furthermore, the authentication method is accessible to public and potential counterfeiters. Also, this prior art does not provide for an accurate measurement of the Curie point, therefore the feature can be imitated by any magnetic material having the Curie point below the temperature of the heater of the authentication device.
A product with a security marking and a method of determining its authenticity are disclosed in US 20010022259 . An image possessing magnetic properties, which disappear at a temperature in the range from -50 to 150°C (Curie temperature for the material used in the method), is applied on the surface of a carrier. According to the prior art, two images having different Curie temperature and different coercive force can be applied on a product (document), and these images can be superimposed. The application also discloses a device for determining the validity, which comprises a magnetization unit, a heating unit and a magnetic detector.
This prior art does not allow application and storage of hidden information on the surface of a valuable document. Images with magnetic properties, disclosed in the invention, including their superposition, are visible.
Most closely related to the present invention is a method of protection of documents, securities or products, using nanodiamonds with active NV centers. This method is based on the use of a complex effect - variation in the photoluminescence intensity under a microwave field ( RU 2357866 ).
The problem of this method is in the intrinsic photoluminescence of nanodiamonds, moreover, the depth of its modulation by a microwave field has a small magnitude (its theoretical limit is about 10%), which requires the use of very sensitive methods of analysis, high concentrations of the substance, and exposure of the document to intensive fields.

SUMMARY OF THE INVENTION

The object is attained owing to the use of a security material having a predetermined combination of magnetic and optical properties, where optical properties are temperature dependent and magnetic properties provide induction heating of the material only in the presence of an alternating magnetic field with specified parameters. The material with complex properties is much more difficult to imitate because it requires the reproduction of not a single property (luminescence in a given spectral band, reflection coefficient, coercive force, etc.), but several properties at the same time, and in a specified combination.
Security marking can be made using a composite material capable of reversibly changing an optical characteristic selected from the group: emissivity in the wavelength range from 0.5 to 15 µm, diffuse reflectance in the range of from 10 to 100% in the wavelength range from 0.2 to 10 µm, refractive index lying in the range of from 1.3 to 4, induced emission in the wavelength range of from 0.2 to 10 µm, spectral sensitivity in the wavelength range of from 0.1 to 10 µm, the ratio of intensity of induced emission bands of from 1 to 1000, rise and decay of spectral bands of the induced emission in the time range of from 10^-6 to 10 ms.
Composite material of the security marking can be produced using an inorganic compound capable of a reversible change in the magnetic permeability and/or magnetic moment.
The product is characterized in that upon the exposure of at least one area of the surface of the security marking to an alternating magnetic field, a hidden image and/or infonnation is formed on the treated area of the surface due to changes in the magnetic and/or optical properties, caused by local heating.
One embodiment of the invention enhances the level of security, enables expert or machine authentication and makes possible multiple check of authenticity of the product, eliminating unintended detection of hidden information between the authentication cycles.
An additional way of implementing the invention is the ability of applying and reading out hidden information that is generated randomly and is detected and read out using a double effect just in the process of machine authentication and, therefore, cannot be reproduced consciously.
The object is also attained by a method of authentication of a product defined above, comprising: exposing particles of an inorganic compound used for applying an initially hidden security marking to an alternating magnetic field; providing local heating due to losses for magnetic reversal, eddy currents or relaxation, and detecting a change in the value of a selected optical and/or magnetic characteristic of the inorganic compound in areas of the marking, which are susceptible to the effect of the external alternating magnetic field, relative to its areas that are insusceptible to this effect, or relative to areas not exposed to the magnetic field having the specified intensity.
After detecting changes in the value of an optical and/or magnetic characteristic, the exposure of the surface to the external alternating magnetic field is stopped, and then reverse characteristic changes are detected on the treated area with the achievement of the value specific to the compound under normal temperature conditions.
If the value of an optical and/or magnetic characteristic of the inorganic compound in the areas of the marking exposed to an external alternating magnetic field changes, respective characteristics are measured or analyzed by instrumental methods, or originally hidden image and/or information is visually detected.
Advantages of the present invention are based on the use of a complex authenticity feature, which consists in a predetermined response to a double effect of the material of the security marking and is not manifested in other conventional publicly available materials (imitators).
When the invention is used to obtain a visual effect for authentication in cash services, the dynamic visual effect may be manifested in visually detected dynamic change of color, brightness of luminescence, pulsation and flashing of the image of the security marking when exposed to a high-frequency alternating magnetic field, the intensity and/or frequency of which are varied according to a predetermined algorithm or are constant.
For purposes of the present invention not only the luminescent glow as such and its dynamic change of various substances in time are of practical interest, but also a variety of optical effects based on properties of photochromic and thermochromic compounds.
Similarly to time variation in the intensity or color of luminescence glow under simultaneous effect of exciting radiation and alternating magnetic field, the invention enables observation of e.g. a periodic change in color of the security marking.
Visual effect according to the invention can be substantially increased if simultaneously with the security marking another graphic element will be observed, which has a similar color or spectrum and/or intensity of the luminescent glow, but does not possess the combination of properties required for producing the dynamically changing effect (and consequently not responsive to a change in the alternating magnetic field).
In context of the present invention, valuable document refers to a banknote, tax stamp, passport, travel document, driving license, identity card, security paper or plastic card.
Security marking may be applied on the surface or embedded into the structure a valuable document. It also can be made by a printing method, preferably by intaglio or screen printing, added to paper stuff and/or paper sizing, embedded in a security fiber added to paper stuff, applied on a security thread or tape added to paper, or disposed, at least partly, on the surface of paper, embedded in plastic or applied on the surface of plastic.
Security marking may preferably have the shape of a patch, circle, concentric circles, concentric polygons, divergent rays, or a combination of these figures, a guilloche element, or any combination of the above.
Security marking can be formed as personal data of the owner of the document, or a substrate under the personal data of the owner applied on the top of the document, and thereby protect the document from unauthorized changes.
A method of authentication a valuable document comprising on its surface or in its structure a special security marking, in accordance with the invention, comprises: exposing to a constant exciting radiation in the UV range; observing the level and color of luminescence, then exposing to an alternating magnetic field and observing a change in the intensity and/or color of luminescent glow.
Furthermore, according to the invention, the security marking can be illuminated with visible light to observe a change in color of a thermochromic compound when exposed to an alternating magnetic field.
The object of enhancing the level of security of a valuable document is attained in the invention also owing to the use in the authentication of the valuable document of a device - a visualizer, which implements the method of authentication of a valuable document and provides optimal conditions for exciting a modulation of the security marking applied on the surface of the valuable document or introduced into its structure, and also optimal conditions for visual detection of a dynamic effect such as a change in color, flashing or pulsations of the observed image of the security marking.
A device that implements the present method of authentication of a valuable document, - a visualizer, provides illumination of the security marking with UV radiation having an optimal power, and formation of an alternating magnetic field varying according to a predetermined time law. The principal feature of the device is the almost complete absence of visually observable dynamic effects on traditional security markings, known from the prior art, for example, stationary luminescence under UV radiation, or stationary anti-Stokes luminescence.
The device may comprise an electronic control unit for automatically turning on and off the field of the inductor in a predetermined time sequence to form the dynamics of changing the brightness of luminescence of the security marking, an external light protection device, and a sample positioning device.
The device operates in the following manner: a valuable document is irradiated with an exciting radiation having a maximum wavelength lying in the UV or blue region of the optical spectrum, and is then exposed to an alternating magnetic field having a predetermined frequency and power with simultaneous visual detection of the resulting dynamic effect, such as change in color, flashing or pulsation of the image of the security marking on the valuable document.
The inventive authentication method enhances the level of counterfeit protection of a valuable document owing to the presence of a visually detected effect such as a change of color, flashing or pulsation of the image of the security marking, the dynamic nature of which is reliably detected by human eye, allowing the use of the invention for authentication of valuable documents by consumers and in cash services, and by broad segments of population.

Brief Description of the Drawings

The invention is illustrated by the drawings in which:

Fig. 1 shows a valuable document in the form of a paper-based banknote (numeral 1) comprising a security marking (numeral 2) applied to its surface by offset printing;
Fig. 2 shows a functional diagram of a device for authentication of a valuable document according to the invention. The device comprises: an external light protection device (numeral 1), a source of exciting radiation in the wavelength range of 330 - 380 nm (numeral 2), a sample stage (numeral 3), on which a banknote (numeral 5) is disposed, a magnetic inductor (numeral 4), and a control unit (not shown).

Description of Preferred Embodiment

The invention can be implemented using the methods described in the examples below.

Example 1

A valuable document in the form of a paper-based banknote (Fig. 1, numeral 1) comprises a security marking (Fig. 1, numeral 2) applied to its surface by offset printing.
The marking contains 80% of a white titanium-based offset binder and 20% of a pigment based on an inorganic compound such as ferro-yttrium garnet doped with 3-valent ions of europium, capable of being heated when exposed to an external alternating magnetic field with a frequency of 10³ KHz.
This substance exhibits a narrow-band luminescence in the visible range with maximum at 625 nm when exposed to an exciting radiation in the range of 330-380 nm. Moreover, brightness of the luminescence depends on the power of the applied exciting radiation.
At the same time, the substance is capable of a visually detected change in its luminescent properties with temperature when exposed to an alternating magnetic field due to the effect of thermal quenching of the luminescence.
Combination of these parameters determines the authenticity of the valuable document.

Example 2

A device for authentication of a valuable document such as a banknote comprising a security marking made in accordance with Example 1.
A functional diagram of a device for authentication of a valuable document is shown in Fig. 2.
The device comprises: a source of exciting radiation in the wavelength range of 330-380 nm (Fig. 2, numeral 2), an external light protection device (Fig. 2, numeral 1), a sample stage (Fig. 2, numeral 3), a magnetic inductor (Fig. 2, numeral 4) and a control unit (not shown).
The banknote (Fig. 2, numeral 5) is positioned on the sample stage.
When the banknote is exposed to UV radiation of the source, red color luminescence can be visually observed. Upon switching on the inductor by the control unit according to a predetermined time law, a periodic decay of the luminescence glow in accordance with the law is observed, which gives evidence of the authenticity of the banknote.

Example 3

A product in the form of an excise stamp comprises on its front side a rectangular colorless security marking made by offset printing.
The security marking comprises 80% of a binder and 20% of a composite material in the form of particles ranging in size from 2 to 5 µm.
Particles of the material consist of a core made of γ -iron oxide Fe₂O₃ and a shell partly deposited on the surface of the core and made of ZnS-based phosphor.
When the security marking is illuminated with radiation in the wavelength range from 330 to 400 nm, visible green color luminescence in the wavelength range 450-610 nm with the spectrum maximum at 540 nm can be observed.
Upon exposure of areas of the security marking to an alternating magnetic field with a frequency of 13.56 MHz, the marking is locally heated to a temperature of 50°C (323 K) at which the intensity of photoluminescence on the treated areas reversibly decreases due to the effect of thermal quenching of luminescence in this spectral band.
The areas exposed to the alternating magnetic field produce a coded sequence in the form of a barcode, which can be read by an optical sensor during the time of recovery of normal intensity of luminescence.
After cooling the marking to the ambient temperature the written information irreversibly disappears and thus becomes inaccessible for observation by people and for counterfeiting.
However, this information may be reproduced an unlimited number of times at repeated authentication of the excise stamp, since the used characteristic of the marking material is reversible.
The combination of measured parameters, including the combination of magnetic and optical properties of the composite material of the marking, and also the reversible change in optical properties of the marking substance in the form of the applied code sequence, can be measured instrumentally to thereby determine the authenticity of the security product.

Example 4

A product in the form of a banknote comprises a colorless security marking formed as a transverse stripe. The marking comprises particles of super-paramagnetic barium ferrite ranging in size from 20 to 80 nm, added directly into paper stuff, and particles of Gd₂O₂S phosphor ranging in size from 1 to 3 µm, also added to paper stuff.
When the security marking is illuminated with a pulsed light in the wavelength range from 330 to 400 nm, visible green luminescence is detected with the spectrum maximum at 514 nm and the decay time constant of about 30 µs.
Upon exposing areas of the security marking to an alternating magnetic field having the frequency of 5 MHz, the marking is locally heated owing to Neel/Brown relaxation to the temperature of 50°C (323 K), at which the decay time constant of luminescence on the treated areas changes reversibly.
The change in the decay time constant can be measured instrumentally during the time of cooling the treated areas of the marking to the ambient temperature.
The combination of measured parameters, including the combination of magnetic and optical properties of the composite material of the marking, and the reversible change in the decay time constant of luminescence can be measured instrumentally and serves as the criterion for the authenticity of the product.

Industrial Applicability

The invention relates to protection of products against counterfeit and can be used for instrumental authentication of printed security products, such as banknotes and forms of security papers, labels, excise and postage stamps, payment and identity documents, passports and travel documents.

Claims

A product comprising a carrier with a security marking applied on its surface, the marking being made with the use of a composite material including a binder and particles of an inorganic compound capable of being heated when exposed to an external alternating magnetic field and comprising in its composition or at least partly comprising on its surface an additional substance capable of changing its optical or magnetic properties with temperature.
The product according to claim 1, characterized in that particles of the inorganic compound are heated when exposed to the external alternating magnetic field preferably due to magnetic reversal losses, and the intensity of the external alternating magnetic field exceeds the coercive force of the composite material.
The product according to claim 1, characterized in that particles of the inorganic compound are heated when exposed to an external alternating magnetic field preferably due to the flow of eddy currents.
The product according to claim 1, characterized in that particles of the inorganic compound are heated when exposed to an external alternating magnetic field preferably due to relaxation losses.
The product according to any one of claims 1 to 4, characterized in that the security marking is made with the use of a composite material capable of reversibly changing the magnetic permeability and/or magnetic moment with temperature.
The product according to any one of claims 1 to 4, characterized in that at a temperature change the composite material of the security marking is capable of reversibly changing an optical and/or magnetic characteristic selected from the group: emissivity in the wavelength range of from 0.5 to 15 µm, diffuse reflectance lying in the range of from 10 to 100% in the wavelength range from 0.2 to 10 µm, refractive index lying in the range of from 1.3 to 4, induced emission in the wavelength range of from 0.2 to 10 µm, spectral sensitivity in the wavelength range of from 0.1 to 10 µm, the ratio of intensity of induced emission bands of from 1 to 1000, rise and decay of spectral bands of induced emission in the time range of from 10⁶ to 10 ms, magnetic susceptibility in the range of from 1 to 10⁶
The product according to any one of claims 1 to 6, characterized in that upon exposing various areas of the surface of the security marking to an alternating magnetic field with a frequency of from 10³ to 10⁸ Hz, a hidden image, code sequence and/or information is formed.
The product according to any one of claims 1 to 7, characterized in that particles of the inorganic compound are ranging in size from 0.01 to 100 µm.
The product according to claim 8, characterized in that the product is a banknote, excise stamp, postage stamp, passport, travel document, driving license, identity card, security paper, plastic card, label, payment document.
The product according to claim 9, characterized in that the security marking is made by a printing method.
The product according to claim 9, characterized in that the security marking is introduced into paper or polymer stuff, or applied as a layer on the surface of paper or polymer, or applied in the composition of an adhesive layer between inner layers of a multilayer product.
The product according to claim 9, characterized in that the security marking is embedded into a security fiber added to paper stuff.
The product according to claim 9, characterized in that the security marking is applied on a security thread or tape introduced into paper or disposed at least partly on the surface of paper.
The product according to claim 10, characterized in that the security marking is made in the shape of geometric figures, guilloche elements, graphic or alphanumeric symbols.
The product according to claim 10, characterized in that the security marking comprises personal information of the owner of the document.
The product according to claim 10, characterized in that the security marking forms a substrate under personal information of the owner of the document, applied on the top, to prevent making unauthorized changes to it.
The product according to any one of claims 10 to 13, characterized in that the security marking is hidden and indistinguishable on the carrier surface when viewed in reflection in the visible range at diffuse lighting.
The product according to any one of claims 10 to 13, characterized in that the security marking comprises at least two layers of dissimilar materials, where one of the materials is capable of being heated when exposed to an external alternating magnetic field, and the other material is capable of reversibly changing its optical properties in the visible light range due to a change in the temperature applied thereto, and relative position of the layers provides a heat exchange between them.
The product according to claim 18, characterized in that the security marking contains in its composition a luminescent compound exhibiting, when exposed to exciting radiation, a glow preferably lying in the visible light range.
The product according to any one of claims 1 to 19, characterized in that the product comprises said security marking and an additional marking exhibiting luminescence in the visible light range, but not capable of reversibly changing its optical properties in the visible light range due to a change in the temperature applied thereto and an alternating magnetic field.
The product according to claim 20, characterized in that both said markings have the same color at room temperature.
The product according to any one of claims 20 and 21, characterized in that both said markings have the same luminescent color when exposed to UV radiation at room temperature.
The product according to any one of claims 1 to 22, characterized in that each particle of the composite compound comprises a two-layer structure, in which a luminescent compound forms a shell for a magnetic compound.
The product according to any one of claims 1 to 22, characterized in that each particle of the composite compound comprises a structure, in which a luminescent compound is included in the composition of a magnetic compound.
A method for authentication of a product, comprising: exposing a security marking to an external magnetic field having a frequency of from 10³ to 10⁸ Hz; heating and detecting a change in the value of a selected optical or magnetic characteristic of the composite material contained in the security marking on the treated areas of the surface relative to its untreated areas.
The method according to claim 25, characterized in that said exposing to an external magnetic field is provided on the security marking comprising particles with a predetermined Curie temperature; said heating is provided preferably due to magnetic reversal losses; and the temperature at which said heating is stopped is measured.
The method according to claim 25, characterized in that after detecting, on a treated area, changes in the value of an optical and/or magnetic characteristic, said exposure of the surface is stopped, and then reverse characteristic changes are detected at the earlier treated area with the attainment of the value inherent to this compound under normal conditions.
The method according to claim 25, characterized in that upon a change in the value of an optical and/or magnetic characteristic of the composite material on the treated areas of the security marking, either respective characteristics are measured and analyzed by instrumental methods, or the originally hidden image and/or information is visually detected.
A method of authentication of a counterfeit-proof valuable document, comprising:
exposing a security marking to an exciting radiation in the ultraviolet range, and observing luminescence of a predetermined luminescent color in the visible light range, then exposing the security marking to an alternating magnetic field having a predetermined frequency and observing a change in the intensity of luminescent glow under the effect of the modulating magnetic field.
The method according to claim 29, characterized in that upon said exposing of the security marking to an alternating magnetic field, the surface area occupied by the security marking and capable of dynamically changing its optical properties is visually compared with any other areas of the image on the document, which are similar in color and/or luminescence glow, but do not exhibit said property.
A device for authentication of a counterfeit-proof valuable document, comprising an exciting radiation source, an ambient light protection device, a sample stage, a magnetic inductor and a magnetic inductor control unit for generating a predetermined time law for varying the frequency of the generated magnetic field.
The device according to claim 31, characterized in that it further comprises a valuable document positioning element in the form of a stop.