DE102013205048A1 - Device and method for authenticating a value or security document - Google Patents

Abstract

The invention relates to a method and a device for verifying the authenticity of a value or security document, the device (1) comprising at least a first AC voltage source, a first transformer (3a) and at least a first electrode (4a), the first transformer (3a) is electrically connected on the input side to the first AC voltage source and on the output side to the first electrode (4a), an output voltage having a first amplitude and an excitation frequency being able to be generated by means of the first AC voltage source, the output voltage being converted into an excitation voltage by means of the first transformer (3a) second amplitude is transformable, the first electrode (3a) generating an electrical excitation field as a function of the excitation voltage, the first transformer (3a) and the first electrode (4a) being designed in such a way that a resonance frequency of a resonant circuit which has at least one second inductance of the first transformer (3a) and a capacitance of the first electrode (4a), greater than or equal to 80 kHz.

Description

The invention relates to an apparatus and a method for checking the authenticity of a value or security document.

Securities or security documents, such as banknotes, personal documents, credit cards and the like, may have so-called security or authenticity features attached to or in the document. These security features may e.g. be stimulated from the outside and analyzed at or after the suggestion. Typical authenticity features are fluorescent pigments which, when excited by a special sensor, can light up and be verified.

It is also known to arrange electroluminescent pigments in or on a value or security document.

The DE 10 2008 047 636 A1 discloses a device for checking the authenticity of a security document, which has at least one electroluminescent security feature electroluminescent at an excitation frequency in a high-voltage alternating field, comprising a sensor unit comprising an excitation module, a condenser system and a detector unit. The security document is moved through the sensor unit and the luminescence light is collected by the condenser system and directed to the detector unit, which detects the luminescence light and spectrally evaluates. In this case, the excitation module has a gap-shaped opening, which overlaps a path of movement of the security document to be checked with its opposite boundary surfaces.

To excite electroluminescent pigments in a value or security document, an air gap must be bridged, e.g. between an electrode and the value or security document. Here, the dielectric strength of the air is a limiting factor for the excitation field. In previous designs, an excitation frequency of a few kHz and a maximum amplitude of the excitation voltage greater than 5 kV, in particular some 5 kV, were found for the air gaps present there.

The DE 44 10 253 C2 discloses a circuit arrangement for the power supply of electroluminescent films, which excites by means of a higher-frequency change in the potentials of two electrodes including a luminous layer, this luminous layer for emitting radiation in the visible range. The document discloses an excitation frequency of 400 Hz.

It is desirable to provide authentication devices, e.g. to be integrated into decentralized, small banknote validators or ATMs. For this purpose, it is necessary to reduce a space of such a device.

Existing devices for authenticity verification do not meet these requirements in a satisfactory manner.

The technical problem arises of providing a device and a method for checking the authenticity of a value or security document, wherein a construction space of the device is minimized and an operational reliability of the device is increased.

The solution of the technical problem results from the objects with the features of claims 1 and 8. Further advantageous embodiments of the invention will become apparent from the dependent claims.

It is a basic idea of the invention to generate an electrical excitation field by means of a resonant circuit, wherein a resonance frequency of the resonant circuit is selected to be higher than usual excitation frequencies. This advantageously allows a voltage amplitude of the excitation voltage to be reduced. This in turn can be a space of elements of the resonant circuit can be reduced.

It proposes a device for checking the authenticity of a value or security document. A security document is any document that is a physical entity that is protected against unauthorized creation and / or corruption by security features. Security features are features that make it difficult to falsify and / or duplicate compared to a simple copy at least. Physical entities that include or form a security feature are referred to as security features. A security document may include multiple security features and / or security elements. For the purposes of the definition herein defined, a security document is always a security element. Examples of security documents that also include value documents representing value include, for example, passports, identity cards, driver's licenses, identity cards, access cards, health insurance cards, banknotes, postage stamps, bank cards, credit cards , Smart cards, tickets and labels.

The value or security document may have an electroluminescent security feature which is at least one Excitation frequency luminesces in a high voltage alternating field. In particular, the value or security document may include so-called electroluminescent pigments.

The device comprises at least a first AC voltage source, a first transformer and at least one first electrode. The first transformer is the input side to the first AC voltage source and the output side electrically connected to the first electrode. By means of the first AC voltage source, an output voltage having a first amplitude and an excitation frequency can be generated. By means of the transformer, the output voltage can be transformed into an excitation voltage having a second amplitude. The second amplitude may be higher than the first amplitude. Furthermore, the first electrode generates an electrical excitation field as a function of the excitation voltage. This means that, depending on the orientation, field lines of the excitation field extend away from a surface of the first electrode or toward the surface of the electrode.

The device may further comprise a housing in which the first AC voltage source, the first transformer and the first electrode are arranged. The first electrode may in particular be arranged on an edge of the housing, so that the electric field lines extend away from this edge of the housing or towards this edge of the housing.

In this case, the housing can form an import volume, opened at least on one side, for the value or security document. In particular, an edge portion or several edge portions of the housing may include or limit the import volume. The import volume may e.g. be formed by two spaced apart with a predetermined distance surfaces of an edge of the housing. In this case, the import volume may be designed as an insertion slot into which the value or security document is inserted along a movement path and from which the value or security document, e.g. after the authenticity check, it is executed again. The import volume may be a volume opened to one side or to several sides.

The first electrode is in this case arranged such that the electric field lines of the excitation field extend at least partially into the import volume or run through the import volume. Thus, a value or security document arranged in the import volume can be subjected to the electrical excitation field.

According to the invention, the first transformer and the first electrode are formed such that a resonant frequency of a resonant circuit comprising at least one secondary inductance of the transformer and a capacitance of the first electrode is greater than or equal to 80 kHz.

In previously conventional devices for authenticity testing excitation frequencies of only a few kHz and excitation voltages were used with an amplitude greater than 5 kV.

The proposed device is therefore operable with a very high resonance frequency, in which case the excitation frequency also corresponds to the resonance frequency. The high excitation frequency advantageously causes a high rate of change of a field reversal of the electrical excitation field (dU / dt). Since the emission excitation of electroluminescent pigments is dependent on the rate of change of the excitation field, the amplitude of the excitation voltage, ie the second amplitude, can thus be reduced. By reducing the amplitude of the excitation voltage, the energy to be stored in the resonant circuit, ie the magnetic or electrical energy to be stored, is also reduced. This advantageously allows a space, e.g. of the transformer, to downsize. For example, the space required for a ferrite core of the transformer, which serves to store the magnetic energy, can be reduced at a lower power. At the same time, the reduction of the maximum voltage of the excitation voltage causes a reduced insulation requirement e.g. from windings of the transformer. Again, this leads to a reduction of space requirements.

Furthermore, it is advantageous that the reduction of the amplitude of the excitation voltage also results in improved reliability of the transformer. This stores e.g. for a human user, with reduced amplitude of the excitation voltage, less energy available to the user e.g. could be dangerous if touched.

Preferably, the resonant frequency is greater than or equal to 80 kHz. Further preferred are 150-250 kHz.

The increase in the resonant frequency and thus the excitation frequency advantageously also makes it possible to minimize the risk of air breakdown during operation of the device since, as explained above, smaller amplitudes of the excitation voltage can be used.

It is possible that the device further comprises a detection device for detecting the radiation emitted by the electroluminescent pigments. Next, the device comprise at least one optical element, such as a lens, to ensure a desired beam path of the emitted radiation.

Furthermore, the device may comprise additional excitation means, in particular optical excitation means, e.g. a device for generating UV radiation include. This can e.g. be arranged so that it also emits a further excitation radiation in the above-explained import volume and thus towards the value or security document.

Furthermore, the device may comprise further excitation means, e.g. encourage further safety pigments on or in the asset or security document. Thus, e.g. a time-delayed excitation of electroluminescent pigments and additional security pigments done. For example, At the same time, irradiation with UV radiation can take place for exposure to the electrical excitation field. Also, so-called photoluminescent pigments can be excited and the radiation emitted by these pigments can be evaluated. For example, the evaluation of the radiation emitted by photoluminescent pigments can be used as so-called predetection. Thus, generation of the electrical excitation field can only take place if at least one evaluation criterion is fulfilled in the evaluation of the radiation emitted by photoluminescent pigments.

For example, the first transformer may have a commercial CCFL transformer design. Thus, in addition advantageously reduce costs in the realization of the proposed device.

Some or all of the above-explained elements of the proposed device may e.g. arranged in a module, e.g. to be shed. The resulting module advantageously has a compact design. Such modules can be integrated, for example, in ATMs.

In a further embodiment, the resonant circuit further comprises a winding capacitance of a secondary winding of the transformer and a resulting capacitance of stray capacitances. Here, the resulting capacity of stray capacitances refers to a resulting capacitance of device-based stray capacitances of the device. Stray capacitances arise e.g. capacitances between elements of the resonant circuit, such as a wiring or parts of the transformer, and an environment, such as a housing.

In this case, a total capacitance of the resonant circuit can be calculated, for example, as follows: Cp = Cw + Ce × Cs Formula 1 where Cp denotes the total capacitance of the resonant circuit, Cw the winding capacity of the secondary inductor, Ce the capacitance of the first electrode or of an electrode assembly comprising the first electrode, and Cs the resulting capacitance of stray capacitances.

As a result, a more accurate modeling of the resonant circuit is made possible in an advantageous manner.

The resonant frequency of the resonant circuit can, for example, as fres = 1 / (2π × sqrt (Ls × Cp)) Formula 2 where fres is the resonant frequency and Ls is the secondary inductance. In this case, a maximum energy stored in the resonant circuit results as Es = (Cp × Us ² ) / 2 Formula 3 where Es denotes the stored energy and Us denotes the maximum voltage amplitude of the excitation voltage.

By reducing the total capacitance Cp, the resonance frequency can thus advantageously be increased on the one side, but the maximum energy stored in the resonant circuit can be lowered. This advantageously enables the reduction of a construction space of the proposed device, since the space is essentially determined by the required space of the transformer and the necessary insulation measures. When reducing the maximum stored in the resonant circuit energy It also reduces the space of the transformer, the high resonant frequency still allows reliable excitation of electroluminescent pigments of a value or security document.

A further advantageous aspect is that with a reduction in the installation space of the transformer, the winding capacitance Cw is likewise reduced, as a result of which, as can be seen from formulas 2 and 3, the resonance frequency fres increases and the maximum energy Es stored in the resonant circuit decreases.

The inventive choice of the resonant frequency thus advantageously causes a reduction in space through various aspects.

In a further embodiment, the secondary inductance of the transformer is at most 0.8 H. Preferably, the secondary inductance is 0.1 H.

Alternatively or cumulatively, a total capacity Cp is at most 30 pF. Preferably, the total capacitance Cp of the resonant circuit 10 is pF.

Experiments have shown that the suggested parameter selection results in a sufficient excitation with a maximum amplitude of the excitation voltage of 3 kV. A maximum stored in the resonant circuit energy It is here about 0.05 mJ. The resonance frequency can reach 150 kHz. A construction volume of the transformer in this case may be, for example, 24 × 20 × 15 mm.

In a further embodiment, the device comprises a further electrode. In this case, the electrical excitation field can form between the first and the further electrode. The further electrode may in particular be arranged at a predetermined distance from the first electrode. If the device has the previously explained import volume, the first electrode can be arranged on or on a surface of a first edge section, for example of a housing of the device, wherein the further electrode can be arranged on a further edge section of the housing, which is the first edge section opposite. The edge sections may include the import volume.

As a result, a desired course of the electric field can be achieved in an advantageous manner.

In a preferred embodiment, the device comprises a further transformer, wherein the further transformer is electrically connected on the input side to the first or a further voltage source and on the output side to the further electrode. By means of the further transformer, a further excitation voltage can be generated on the output side. The further excitation voltage has a phase offset of 180 ° to the first excitation voltage.

If the further transformer is connected on the input side to the first voltage source, an amplitude of the further excitation voltage can be greater than the amplitude of the output voltage of the first AC voltage source. If the further transformer is connected on the input side to a further AC voltage source, then an output voltage of the further transformer can have a greater amplitude than an output voltage of the further AC voltage source.

Preferably, however, the first excitation voltage generated by the first transformer and the further excitation voltage generated by the further transformer have amplitudes of equal magnitude.

The phase offset proposed according to the invention advantageously results in that a maximum amplitude of the resulting excitation voltage which generates the electrical excitation field between the electrodes is greater than, in particular twice as large as, the maximum amplitude of the first excitation voltage or the further excitation voltage. For example, a resulting excitation voltage having a maximum amplitude of 3 kV can be generated by the excitation voltage generated by the first transformer having a maximum amplitude of 1.5 kV and the excitation voltage generated by the further transformer also having an amplitude of 1.5 kV.

As a result, it is thus advantageously possible to reduce maximum amplitudes of voltages which are generated on the secondary side of the respective transformer. This in turn means that an installation space of the transformers and the requirements for the insulation can be reduced in an advantageous manner.

This in turn advantageously allows miniaturized transformer designs to be used which are commercially available.

It could be shown in experiments that a reduction of a construction volume to 10% of the usual building volume is possible.

In a further embodiment, the device is designed such that the device forms the previously explained import volume for the value or security document to be checked. The first and the further electrodes are arranged on opposite sides of the insertion volume at a predetermined first distance. Further, the first and the further electrode are arranged transversely to an insertion direction of the value or security document at a predetermined further distance.

The insertion direction can be defined here, for example, as a first direction. The first distance then designates a distance in a second direction which is oriented perpendicular to the first direction. Further, the second direction may be perpendicular to a surface of a value or security document to be checked, if this is arranged in the import volume. In this case, it is also possible that the second direction is oriented perpendicular to surfaces of edge portions of the housing of the device, wherein the edge portions comprise the import volume at least partially. In this case, therefore, the first and the further electrode, as previously explained, arranged on opposite sides or edge portions of the housing.

Furthermore, the first and the further electrodes can be arranged at a distance from the predetermined further spacing with respect to the insertion direction, that is to say in a third direction, the third direction being oriented perpendicular to the first direction and perpendicular to the second direction.

This advantageously results in that the electric field which forms between the first and the further electrode comprises both portions in the second direction and portions in the third direction. In this case, the proportions in the third direction can be essential for the excitation of electroluminescent pigments in a value or security document to be checked.

Of course, further arrangements of the electrodes are conceivable. For example, the electrodes can also, as in the DE 10 2008 047 636 A1 described, be arranged relative to each other. In this regard, therefore, in particular the 2 . 4a . 4b . 5 . 6a . 6b . 7 . 8th and 9 and the corresponding explanations in the description.

In a preferred embodiment, the predetermined first distance is between 0.5 mm and 2.0 mm and the predetermined further distance is 1.0 mm to 3.0 mm.

The proposed distances in this case advantageously result in a reduction of the capacitance Ce of the capacitor arrangement as well as a reduction of the resulting stray capacitances Cs.

Further proposed is a method for checking the authenticity of a value or security document by means of a device according to one of the previously described embodiments. In this case, the output voltage is generated at the resonant frequency of the resonant circuit by means of the first AC voltage source. If the device comprises two alternating voltage sources, then the output voltages of both alternating voltage sources are respectively generated with the resonance frequency of the resonant circuit. As described above, in this case, the output voltages of the AC power sources can be generated with a phase shift of 180 °. Further, an amplitude of the output voltage (s) may be selected such that the excitation voltage (s) generated by the transformer (s) has a desired amplitude.

By operating the resonant resonant circuit in its resonant frequency, an energy for exciting the electroluminescent pigments is reduced in an advantageous manner. However, since the resonant frequency, as explained above, corresponds to a high excitation frequency, the excitation can nevertheless take place with a device which has a low space requirement.

In a further embodiment, an excitation voltage has an amplitude of at most 3 kV. If excitation voltages are generated by two transformers, an amplitude of the individual excitation voltages can amount to a maximum of 1.5 kV.

This advantageously makes it possible to generate an electrical excitation field with a low excitation voltage, which on the one hand provides operational safety for e.g. Increase a user and at the same time provide the previously discussed reduced requirements for an insulation requirement, which in turn minimize space requirements.

In a further embodiment, in addition to an excitation field, a further excitation radiation for excitation of further optical features of the value or security document is generated. The further excitation radiation may in particular be an optical radiation, preferably a UV radiation or an IR radiation.

In particular, the excitation field and the further excitation radiation can be generated in such a way that they irradiate the same spatial sections of the value or security document.

In this way, it is advantageously possible to excite further optical security features or elements of the value or security document and to evaluate the radiation emitted by the corresponding feature due to the further excitation radiation. In particular, it is possible that a further optical feature of the electroluminescent pigment is excited. Here, the electroluminescent pigment in addition to the electroluminescent properties also have photoluminescent properties that allow the electroluminescent pigment through the stimulate further excitation radiation. By the excitation of further optical features and a corresponding evaluation of the radiation emitted by these, also a verification can be advantageously improved.

In a further embodiment, the excitation field is generated only when an optical feature excited by the further excitation radiation has been detected. Thus, the generation of the excitation voltage occurs only when an excited by the further excitation radiation optical feature was detected. The excitation voltage and thus the excitation field is therefore generated only after the further excitation radiation.

This is particularly advantageous if, as explained above, the electroluminescent pigment also has photoluminescent properties in addition to the electroluminescent properties. Namely, in this case, the detection of the optical characteristic ensures that an electroluminescent pigment is contained in the value or security document. Preferably, a spatial portion of the value or security document can be determined in which the pigment is arranged. This subsequently enables a targeted excitation of the electroluminescent properties. At the same time, operational reliability is also increased since it can be ruled out that spatial sections of the security document are exposed to the excitation field which contain no electroluminescent pigments. For example, plasma formation and / or breakdown that would occur when portions of the security document with a hologram or security threads are exposed to the excitation field can be avoided.

The invention will be explained in more detail with reference to an embodiment. The single FIGURE shows a schematic block diagram of a device according to the invention.

In 1 is a schematic block diagram of a device according to the invention 1 shown. The device comprises a first module 2a and a second module 2 B , A module 2a . 2 B may here denote a structural unit, which has, for example, a housing.

Every module 2a . 2 B includes a transformer 3a . 3b , Next includes each module 2a . 2 B an electrode 4a . 4b , Next includes each module 2a . 2 B optical elements 5a . 5b , which are designed and arranged such radiation 6 that of an electroluminescent pigment 7 is emitted to a detection device 8a . 8b to steer. This includes each module 2a . 2 B such a detection device 8a . 8b , Further illustrated are facilities 9a . 9b for generating a UV radiation 10 , Next each module indicates 2a . 2 B a control and evaluation device 11a . 11b on. Not shown is an AC voltage source that is electrically connected to the transformer 3a of the first module 2a and the transformer 3b of the second module 2 B is connected, the transformers 3a . 3b electrically connected in parallel to each other. Here, the AC voltage source is so with the transformer 3b of the second module 2 B connected to an input voltage of the transformer 3b of the second module 2 B , That is, a voltage that drops across a primary winding, not shown, 180 ° out of phase with an input voltage of the transformer 3a of the first module 2a is. The modules 2a . 2 B are similar here. This means that the geometric arrangement of the elements of the modules 2a . 2 B For example, refer to a geometric center of the modules 2a . 2 B is equal to. The modules 2a . 2 B are within the device 1 arranged so that these have an import volume 12 lock in. The import volume 12 is especially from a border section 13a a housing of the first module 2a and a border section 13b a housing of the second module 2 B includes.

Also shown is a value or security document 14 which is in the import volume 12 is arranged. The value or security document 14 can be moved along the first direction z by the import volume, wherein the first direction z in 1 oriented in the plane of the drawing. The first direction z thus indicates a direction of movement of a movement path or an insertion direction for the value or security document 14 in front. The electrodes 4a . 4b of the first module 2a and the second module 2 B are spaced apart at a predetermined first distance VA. The first distance VA is in this case measured in a second direction y, wherein the second direction y is oriented perpendicular to the first direction z. The second direction y may in this case in particular be perpendicular to surfaces of the previously explained edge sections 13a . 13b be. Also shown is a third direction x, wherein the directions x, y, z form a Cartesian coordinate system. The electrodes 4a . 4b are here in the range of the respective edge section 13a . 13b arranged. In this case, the first distance VA can be a distance from electrode surfaces of the electrodes 4a . 4b or a distance of the geometric centers of the electrodes 4a . 4b be.

It is further shown that the electrodes 4a . 4b the modules 2a . 2 B at a predetermined further distance LA from each other along the third direction x are spaced. The further distance LA can in this case be, for example, a distance from geometric center points of the electrodes 4a . 4b or from geometric centers of the electrode surfaces of the electrodes 4a . 4b be.

A first resonant circuit is provided by a secondary inductance of the transformer 3a of the first module 2a , a capacitance of the electrode assembly from the electrodes 4a . 4b , a winding capacity of a secondary winding of the transformer 3a of the first module 2a and a resulting capacity of stray capacitances of the first module 2a educated. Another resonant circuit is provided by the corresponding elements of the second module 2 B educated. In this case, the AC voltage source, not shown, is operated such that the resonant circuits are excited with their resonant frequency which is greater than or equal to 80 kHz. In this case, forms between the electrodes 4a . 4b an electrical excitation field 17 having a proportion in the third direction x.

These contributions in the third direction x excite the electroluminescent pigments 7 value or security document 14 at.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102008047636 A1 [0004, 0052]
• DE 4410253 C2 [0006]

Claims (11)

Apparatus for checking the authenticity of a value or security document, the apparatus ( 1 ) at least a first AC voltage source, a first transformer ( 3a ) and at least one first electrode ( 4a ), wherein the first transformer ( 3a ) on the input side with the first AC voltage source and on the output side with the first electrode ( 4a ) is electrically connected, wherein by means of the first AC voltage source, an output voltage having a first amplitude and an excitation frequency can be generated, wherein by means of the first transformer ( 3a ) the output voltage is transformable into an excitation voltage having a second amplitude, the first electrode ( 3a ) generates an electric excitation field as a function of the excitation voltage, characterized in that the first transformer ( 3a ) and the first electrode ( 4a ) are formed such that a resonant frequency of a resonant circuit, the at least one secondary inductance of the first transformer ( 3a ) and a capacity of the first electrode ( 4a ) is greater than or equal to 80 kHz. Apparatus according to claim 1, characterized in that the resonant circuit further comprises a winding capacitance of a secondary winding of the first transformer ( 3a ) and a resulting capacity of stray capacitances. Device according to claim 1 or 2, characterized in that the secondary inductance is at most 0.8 H and / or a total capacitance of the resonant circuit is at most 30 pF. Device according to one of claims 1 to 3, characterized in that the device ( 1 ) another electrode ( 4a ). Device according to one of claims 1 to 4, characterized in that the device ( 1 ) another transformer ( 3b ), wherein the further transformer ( 3b ) on the input side with the first or a further AC voltage source and on the output side with the further electrode ( 4b ) is electrically connected, wherein by means of the further transformer ( 3b ) on the output side, a further excitation voltage can be generated, wherein the further excitation voltage has a phase offset of 180 ° to the first excitation voltage. Device according to one of claims 4 to 5, characterized in that device ( 1 ) is designed such that the device ( 1 ) an import volume ( 12 ) for the value or security document to be checked ( 14 ), wherein the first and the further electrode ( 4a . 4b ) on opposite sides of the import volume ( 12 ) are arranged at a predetermined first distance (VA) and wherein the first and the further electrode ( 4a . 4b ) transverse to an insertion direction of the value or security document ( 14 ) are arranged at a further predetermined distance (LA) spaced. Apparatus according to claim 6, characterized in that the first distance (VA) between 0.5 mm and 2.0 mm and the further predetermined distance (LA) is 1.0 mm to 3.0 mm. Method for checking the authenticity of a value or security document by means of a device ( 1 ) according to one of claims 1 to 7, characterized in that by means of the first AC voltage source, the output voltage is generated at the resonant frequency of the resonant circuit. A method according to claim 8, characterized in that an excitation voltage has a maximum amplitude of 3 kV. Method according to one of claims 8 or 9, characterized in that in addition to an excitation field, a further excitation radiation for excitation of further optical features of the value or security document is generated. A method according to claim 10, characterized in that the excitation field is generated only when an excited by the further excitation radiation optical feature was detected.

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