EP2976680A1

EP2976680A1 - Device and method for exciting electroluminescent pigments without contact

Info

Publication number: EP2976680A1
Application number: EP14711746.9A
Authority: EP
Inventors: Jörg Fischer; Markus Tietke; Stefan TRÖLENBERG; Olga Kulikovska; Lazar KULIKOVSKY; Peer KRÜGER; Manfred Paeschke
Original assignee: Bundesdruckerei GmbH
Current assignee: Bundesdruckerei GmbH
Priority date: 2013-03-21
Filing date: 2014-03-20
Publication date: 2016-01-27
Anticipated expiration: 2034-03-20
Also published as: CN105247417B; TW201443789A; TWI625676B; CN105247417A; EP2976680B1; DE102013205052A1; WO2014147169A1

Abstract

The invention relates to a device for exciting at least one electroluminescent pigment, in particular in a value document or security document (2), without contact, wherein the device (1) comprises at least one electrode (6), wherein the at least one electrode (6) is designed in such a way that an electric flux density of the field (7) that can be generated by the electrode (6) in a predetermined emission direction (9) changes. The invention further relates to a method for contactless excitement.

Description

DEVICE AND METHOD FOR THE CONTACTLESS IRONING OF ELECTROLUMINESCENT PIGMENTS

The invention relates to a device and a method for contactless excitation of at least one electroluminescent pigment, in particular in 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.

EP 1 631 461 B1 discloses a document of value having at least one security element which comprises a marking layer comprising electroluminescent pigments applied to a carrier region in a marking region, wherein a plurality of field displacement elements each having a dielectric constant of more than 50 are electrically distributed in the marking region is arranged, which have a mean distance from each other of about 5 μηι to 500 μηι to form spaces for the electroluminescent pigments, and increase a macroscopically impressed electric field strength locally in the interstices.

DE 10 2008 047 636 A1 discloses a device for checking the authenticity of a security document, which is at least one at an excitation frequency in a

High-voltage alternating field has electroluminescent security feature, with a sensor unit containing an excitation module, a condenser system and a

Detector unit includes. The security document is moved by the sensor unit and the luminescent light is collected by the condenser system and applied to the

Directed detector unit, which detects the luminescence and spectrally evaluates. In this case, the excitation module has a gap-shaped opening, which has a Movement path of the security document to be checked with their opposite boundary surfaces overlaps.

DE 199 03 988 A1 describes a device for the validation of

Authenticity features on value and security documents, in particular banknotes, personal documents, plastic cards and the like, which consists of a testing machine, in which the banknotes to be checked are fed and in this case pass through a detector device. The detector device is suitable

to detect and evaluate electroluminescent properties of the authenticity features.

For exciting electroluminescent pigments in a value or

Security document is to bridge an air gap, e.g. between an electrode and the value or security document. Here forms a

Dielectric strength of the air is a limiting factor for the excitation field. In previous designs, there was one for the existing air routes

Excitation frequency of 30 kHz and a maximum amplitude of the excitation voltage of 30 kV.

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.

It raises the technical problem, a device and a method for

to provide contactless excitation of at least one electroluminescent pigment, which allows a reliable and targeted excitation with a reduced maximum amplitude of an AC voltage for generating.

The solution of the technical problem results from the objects with the features of claims 1 and 9. Further advantageous embodiments of the invention will become apparent from the dependent claims. It is a basic idea of the invention to design an electrode of a device for contactless excitation such that field lines of an electric field generated by the electrode are locally concentrated. In this way, a spatially local increase in an electrical flux density can be achieved, which advantageously allows improved and more reliable excitation of electroluminescent pigments.

According to a first aspect of the invention, a device for contactless excitation of at least one electroluminescent pigment, in particular in a value or security document, is proposed. The electroluminescent pigment may be included in a security element of a security or value document. Thus, the device can also for contactless excitation of at least one

Security elements of a value or security document with electroluminescent pigments serve.

The device may thus be part of a document checking device by means of which security features or elements of a value or security document can be verified.

A security document is any document that is a physical entity that is against unauthorized production and / or corruption

Security features are protected. 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 defined herein, a security document also always constitutes a security element. Examples of security documents, which also include value documents representing a value, include, for example, passports, identity cards, driving licenses, identity cards, access control cards, health insurance cards,

Banknotes, postage stamps, bank cards, credit cards, smart cards, and tickets

Labels.

The device comprises at least one electrode. In this case, it is possible that the device comprises exactly one electrode. The electrode serves to generate a electric field, which is also referred to below as the excitation field. This is generated when an AC voltage is applied to the electrode. The alternating voltage applied to the electrode is referred to below as the excitation voltage. The excitation voltage can be generated by an AC voltage source. It is also possible that the excitation voltage is an output voltage of a transformer, wherein an input voltage of the transformer is generated by an AC voltage source. The AC voltage source can

For example, comprise a DC voltage source and an inverter, wherein the AC voltage is an output voltage of the inverter.

Thus, when the excitation voltage is applied to the electrode, an electric field is generated whose field lines extend away from the electrode.

Furthermore, the at least one electrode is designed such that an electrical flux density of the electric field that can be generated by the electrode in a predetermined emission direction changes. In particular, an electrical flux density increases and forms at least a maximum.

The predetermined radiation direction may designate a direction directed from the electrode toward the asset or security document. In particular, the

Direction of emission of the electrode perpendicular to a surface of the value or

Be oriented to security document. Also, the emission direction may be oriented parallel to a central longitudinal axis of the electrode and away from a free end of the electrode.

The fact that an electric flux density of the electric field which can be generated by the electrode in a predetermined emission direction means that the flux density changes in a cross-sectional plane which is oriented perpendicular to the predetermined emission direction of the electrode. In particular, at least one spatial area with a higher flux density than in adjacent areas may be present in the cross-sectional plane.

For example, the flux density can change along a direction perpendicular to the emission direction. In this case, the flux density in the cross-sectional plane continuous, not jumpy, change. For example, the flux density can change linearly or exponentially, in particular increase or decrease.

As a result, at least one region with an increased electrical flux density is generated by a construction of the electrode in an advantageous manner.

In particular, a field bundling can thus take place, through which a spatial

Concentration of the electric field is achieved. In this way, a reliable excitation of at least one electroluminescent pigment can be achieved, since an improved excitation is also made possible by a concentration of the excitation field.

Furthermore, it is advantageously possible for an amplitude of the

Excitation voltage can be reduced. Since both higher flux densities and higher amplitudes cause an improved or stronger excitation of the electroluminescent pigment, the amplitude can be lowered due to the at least one region having a high flux density, with a strength of the excitation remaining at least constant.

The reduction in the amplitude of the excitation field, in turn, advantageously allows adverse effects of high amplitudes, such as a plasma formation in an air gap, a voltage breakdown, an undesired radiation behavior of a field with high field strength, an electromagnetic interference further

electronic components and high energy consumption can be avoided.

Furthermore, the device has a plurality of electrodes, wherein each of the electrodes is designed such that the electrical flux density of the field which can be generated by an electrode in a predetermined emission direction changes. Thus, the device comprises a plurality of electrodes according to one of the previously explained

Embodiments is formed.

According to the invention, all electrodes have a common emission direction.

In this case, it is particularly possible that in a cross-sectional plane, which is oriented perpendicular to all emission directions, several areas with maximum electrical flux density occur. As a result, an excitation of an electroluminescent pigment is facilitated in an advantageous manner, if a precise position of the electroluminescent pigment, for example, in a value or security document is not known. In particular, the proposed device generates a resulting excitation field with multiple regions of maximum flux density. If the excitation field generated in this way is applied, for example, to a value or security document having at least one electroluminescent pigment, then the probability increases that at least one electroluminescent pigment is arranged in a region with a high or maximum flux density. Of course, by such an electrode also several, in particular a plurality, of electroluminescent pigments are excited. For example, electroluminescent pigments with a size in the nanometer range can be stochastically distributed in a security element. Electroluminescent pigments can then be excited in an excitation region having a diameter of 1 mm by means of an electrode having an outer diameter of, for example, ^" Ein." A great advantage of using a plurality of electrodes is that the excitation region and thus the luminous surface increase.

In a further embodiment, an electrical flux density of the excitation field changes in a predetermined region of a cross-sectional plane, which is oriented perpendicular to a predetermined emission direction of the electrode. In this case, the predetermined area is penetrated by the entire or a predetermined portion of the electric field generated by the electrode, that is to say by the excitation field. This describes a size of the area in the cross-sectional plane. The predetermined proportion may be defined, for example, by a predetermined percentage, for example 95%, 90% or 85%.

In this case, the change in the flux density takes place in the region of the cross-sectional plane interspersed by the excitation field or a predetermined proportion thereof. Thus, in particular, no constant flux density, e.g. at a

Plate capacitor, available.

It is also possible that the predetermined range is equal to or smaller than a range defined by a border of the electrode projected into the cross-sectional plane is included. If an outer diameter, in particular a maximum outer diameter, of the proposed electrode is projected into the cross-sectional plane, then the region can thus be formed by the maximum outer diameter

Outline includes.

In particular, the changing flux density in the predetermined range may have exactly one maximum.

The proposed device allows advantageously that by the

Electrode in the emission a local spatial concentration of field lines is generated, whereby, as previously described, a reliability of the excitation of the at least one electroluminescent pigment is increased.

In a further embodiment, in at least a partial region of the predetermined region of the cross-sectional plane, the electrical flux density is higher than in further partial regions of the predetermined region. For example, the electric

Flux density be higher than 1 x 10 ^{~ 7} C / m ² . As explained above, it is possible that in a portion of the predetermined area of the cross-sectional plane, the electric flux density is higher than in any remaining portions. Thus, exactly one area with a high flux density is generated. This allows a targeted and reliable excitation of at least one electroluminescent pigment by the electrode designed as proposed.

In a further embodiment, the at least one electrode tapers towards a radiation-side end. The emission end of the electrode in this case denotes an end from which the excitation field, in particular its field lines, from the

Electrode be radiated toward, in particular towards the at least one value or security document. In particular, the emitting end may be a free end of the electrode.

The taper here denotes, for example, a reduction of a diameter, wherein the diameter can be measured, for example, perpendicular to a central longitudinal axis. As previously explained, the central longitudinal axis may be parallel to or equal to the predetermined emission direction. The taper results in an increase in the flux density of the excitation field radiated in the emission direction, in particular as the taper increases, since the taper causes field focusing.

Thus, an easy-to-implement structural design of the at least one electrode results in an advantageous manner.

In a further embodiment, the electrode has a conical section. Alternatively, the electrode may have a cone-shaped portion.

Here, the proposed sections are designed such that the electrode tapers towards the emission end.

The above-described forms of the sections in this case advantageously allow the desired field concentration, at the same time allowing a simple structural design of the electrode.

In a further embodiment, the electrode is formed as a wire. The wire may be formed, for example, of a conductive material. For example, the wire can be made of copper, silver or gold, but preferably of carbon fiber.

The wire may have a predetermined maximum diameter. The maximum diameter may be, for example, 1 mm. Diameters of up to 0.1 mm are preferred. For larger diameters, a tapered free wire end, in particular a pointed wire end, is advantageous.

The wire-shaped design results in a high, advantageously

Field focusing and a particularly easy manufacturability of the electrode.

In another embodiment, a distance of an electrode to an adjacent electrode is less than or equal to a predetermined maximum distance. The distance can be measured perpendicular to the emission direction. In particular, can Thus, all electrodes extend parallel to each other, wherein, for example, central longitudinal axes of the electrodes are oriented parallel to each other.

The distance between the individual electrodes also determines the distance of regions with high flux density in the resulting excitation field. By selecting the distance, therefore, a spatial distribution of areas with high or maximum flux density can be realized as desired.

The predetermined maximum distance may be, for example, 5 mm.

It is possible that the electrodes are arranged like a comb. In this case, the individual electrodes form teeth of a comb structure. The electrodes can also be arranged like a matrix. In this case, the individual electrodes form rows and columns of a matrix. In the matrix-like arrangement, a distance and a direction to the at least one adjacent electrode in the row and / or column direction are constant.

It is also possible that the electrodes are arranged like tufts or bundles. Here, a distribution of the electrodes in the previously explained

Cross-sectional level have no defined, but a random pattern. For example, in a random pattern, a distance and a direction to the adjacent electrode may vary.

With a uniform distribution of the electrodes in the cross-sectional plane results in an advantageous manner, a uniform distribution of areas with high or maximum flux density. This can be advantageous in particular if

electroluminescent pigments in a security document e.g. are also arranged with the same distance as possible to each other.

In a tuft-like or bundle-like arrangement of the electrodes results in

Advantageously, that also a spatial distribution of areas of

Excitation field with high or maximum flux density is random. This is particularly advantageous when e.g. in a value or security document

electroluminescent pigments are randomly arranged. A random distribution of the pigments results, for example, when, as usual, either a printing ink be added or randomly distributed in the substrate production in this.

Furthermore, the electrodes can be arranged such that the electrodes encompass or surround an area, wherein an optical sensor and / or optical elements for beam guidance are arranged in this area. For example, the

Electrodes include a range, in this area as an optical

Detection channel serving channel is arranged. In the channel can / can

For example, be arranged the optical sensor and / or other optical elements.

The region may be, for example, an area enclosed by a connecting line of the electrodes. The area may in this case have a predetermined size. Thus, the electrodes may be arranged around means for optical detection.

In a further embodiment, a plurality of electrodes are electrically contacted together. As a result, the excitation voltage can be applied to a plurality of electrodes simultaneously in an advantageous manner, as a result of which the excitation fields generated by the individual electrodes also have the same phase position.

At the same time, a required installation space is advantageously reduced and the electrical contacting of the individual electrodes is simplified.

Overall, the proposed device allows e.g. one

Document verification device for verification of a value or security document can be formed with at least one electroluminescent pigment with the smallest possible space.

Furthermore, it advantageously results that a circuit complexity for the proposed device can be minimized, in particular if several electrodes are electrically contacted together. The proposed electrode shapes advantageously allow only a small installation space for the electrodes to be required. By the previously described possibility of reducing an amplitude of the excitation voltage, it results in an advantageous manner that fewer further disturbing effects occur. Thus, an electromechanical compatibility of the proposed device be improved. Also, energy consumption in generating the

Excitation field can be reduced.

Thus, a document verification apparatus including the above-mentioned apparatus will also be described. The document checking device can be designed, for example, as a battery-operated, portable handheld device or be part of such a handheld device. For example, the document checker may be pin-shaped, wherein the electrode is disposed on a tapered portion of the pin. With such a pen, a simple verification of a value or security document can advantageously be carried out by a user manually aligning the pen relative to the value or security document.

The document tester can hereby comprise further components,

For example, the previously explained AC voltage source and transformer.

Alternatively, the device may be placed in a e.g. stationarily arranged document tester are integrated to e.g. a value or security document

Security feature machine-readable to check.

In particular, in the second alternative, the document checking device can comprise, for example, an optical detection device for detecting the radiation emitted by the at least one electroluminescent pigment. These

Detection means may comprise an image capture means, e.g. a CCD camera, a light sensor, e.g. a photodiode, or other components for spectral detection of the emitted light. Also, the tester may include other optical elements, e.g. Lenses or mirrors, for deflecting and / or bundling of the emitted radiation.

A value or security document, for example, can be introduced into the document checking device in such a way that the emission direction explained above is oriented perpendicular to a surface of the value or security document.

Also, the at least one electrode can be so relative to the value or

Safety document can be arranged that a distance between the electrode and a surface of the value or security document is a maximum of 20 mm, preferably a maximum of 5 mm. The minimum distance can be 0 mm, so that the electrode and the document touch each other. However, the distance is preferably at least 0.5 mm, in particular if the electrode is not protected against mechanical wear.

According to the first aspect of the invention, a method for contactless excitation of at least one electroluminescent pigment, in particular in a value or security document, is also proposed. This is an electrical

AC voltage applied to at least one electrode. The applied to the electrode electrical alternating voltage can also be referred to as excitation voltage. The at least one electrode is designed such that an electrical flux density of the field generated by the electrode in a predetermined emission direction changes. The electric field forms the excitation field. The electrode is thus formed according to one of the previously described embodiments. A device for contactless excitation has a plurality of electrodes, wherein each of the electrodes is designed such that the electrical flux density of the field which can be generated by an electrode in a predetermined emission direction changes.

According to the invention, all electrodes have a common emission direction.

The method can in this case be carried out by means of a device according to one of the previously described embodiments.

Furthermore, the electrode can be oriented in such a way that the emission direction is directed to the value or security document, in particular directed perpendicularly to a surface of the security or security document.

Further, the AC electrical voltage can be generated such that a

Amplitude of the excitation voltage is in a range of 100 V to 5 kV. Also, a frequency of the excitation voltage can be adjusted. In particular, a frequency may be in a range of 30 kHz to 20 MHz. Preferably lies the

Excitation frequency in a range of 70 kHz to 100 kHz. The excitation voltage may take various forms. For example, the excitation voltage may be a square-wave voltage, a triangular voltage, a trapezoidal voltage, but preferably a sinusoidal voltage.

According to a further aspect of the invention, to solve the technical problem, a device for contactless excitation of at least one electroluminescent pigment, in particular in a value or security document serve, wherein the device comprises at least one electrode, wherein the at least one electrode is formed such that an electrical flux density of the field generated by the electrode in a predetermined emission direction changes. According to the further aspect, a method for contactless excitation of at least one electroluminescent pigment, in particular in a value or security document, serve to solve the technical problem, wherein an alternating electrical voltage is applied to at least one electrode, wherein the at least one electrode is formed in that an electrical flux density of the electric field generated by the electrode in a predetermined emission direction changes. In this case, the device according to the further aspect can be further developed with the technical features which serve for the further development of the device according to the first aspect. The method according to the further aspect can be developed here with the technical features that serve the development of the method according to the first aspect. These developments have the same advantages as the developments of the device and the method according to the first aspect. The method according to the further aspect can in this case be carried out by means of a device according to the further aspect.

The invention will be explained in more detail with reference to several embodiments. The figures show:

Fig. 1 is a schematic block diagram of a device for contactless

Excitation of at least one electroluminescent pigment,

2a shows a cross section through an electrode according to the invention,

2b shows a cross section through a further electrode, 3 shows a schematic representation of an electrode according to the invention and of a value or security document,

4 shows a schematic representation of a tuft-type electrode arrangement and of a value or security document,

Fig. 5 is a plan view of the tuft-like shown in Fig. 4

Electrode assembly,

Fig. 6 is a plan view of a further electrode assembly and

Fig. 7 is a schematic representation of that shown in Fig. 6

Electrode assembly and a value or security document.

Hereinafter, like reference numerals designate elements having the same or similar technical features.

Fig. 1 is a schematic block diagram of a device 1 for non-contact excitation of at least one electroluminescent pigment (not shown) in a value or security document 2 (see, for example, Fig. 3). The device 1 comprises a DC voltage source 3, for example a battery. The

DC voltage source 3 is electrically connected to an inverter 4, the device 1 also includes. By means of the inverter 4 is a

Output voltage of the DC voltage source 3 in an AC voltage with a predetermined excitation frequency changeable. On the output side, the inverter 4 is electrically connected to a transformer 5. The transformer 5 converts the AC voltage generated by the inverter 4 into an excitation voltage having a desired amplitude. On the output side, the transformer 5 is connected to a schematically illustrated electrode 6, wherein the excitation voltage generated by the transformer 5 is applied to the electrode 6. In this case, the electrode 6 generates an excitation field 7, as explained in more detail below. Thus, an electrical excitation field can be generated by means of a resonant circuit, wherein a resonant frequency of the resonant circuit can be selected higher than previously common excitation frequencies of up to 30 kHz. 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. The resonant circuit may e.g. at least one

Secondary inductance of the transformer and a capacity of the electrode exist. Excitation frequencies of 30 kHz and excitation voltages with an amplitude of up to 30 kV have been used in previously conventional document verification devices.

The high excitation frequency causes a high in an advantageous manner

Rate of change of a field reversal of the electrical excitation field (dU / dt). Since the emission excitation of electroluminescent pigments is also dependent on the rate of change of the excitation field, the amplitude of the excitation voltage 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, reducing the maximum voltage causes the

Excitation voltage has a reduced insulation requirement e.g. from turns of the

Transformer. Again, this leads to a reduction of space requirements. Furthermore, this undesirable heating of the system is avoided or limited.

Furthermore, it is advantageous that, when reducing the amplitude of the

Excitation voltage also results in improved reliability of the transformer. This stores eg for a human user, with reduced amplitude of the excitation voltage less energy that could be dangerous to the user, for example, when touched. The excitation voltage can have a maximum amplitude of 6 kV. The

Excitation field 7 (see, e.g., Fig. 2a) serves to excite

electroluminescent pigments in the value or security document 2.

FIG. 2 a shows a cross section through an electrode 6 according to the invention. The electrode 6 has a central longitudinal axis 8. Further shown is a

Radiation direction 9 of the electrode 6. This is oriented parallel to the central longitudinal axis 8. The electrode 6 tapers towards a radiation-side end 10. In this case, the electrode 6 has a conical section 11 at the emission-side end 10. Furthermore, FIG. 2 a shows a profile of field lines of the excitation field 7, which extend away from the electrode 6. In a cross-sectional plane 12, which is oriented perpendicular to the emission direction 9, an electrical flux density of the

Excitation field 7. Specifically, the electric flux density changes in a predetermined range 13, the predetermined range being permeated by the entire electric excitation field 7 generated by the electrode 6. Here, it is shown that the flux density increases from edges of the region 13 toward a point where the central longitudinal axis 8 intersects the cross-sectional plane 12. Thus, the spatial distribution of the electrical flux density of the excitation field 7 has exactly one area with maximum flux density.

In Fig. 2b, another electrode 14 is shown in a cross section. Also shown is a cross-sectional plane 12 that is perpendicular to a central one

Direction of radiation 9 of the electrode 14 is oriented. Also shown is the region 13, which is penetrated by the entire excitation field generated by the electrode. In contrast to Fig. 2a, however, the electric flux density does not increase toward the point where a central longitudinal axis 8 of the electrode 14 intersects the cross-sectional plane 12. This does not achieve the desired local spatial concentration of field lines, which is a reliable excitation of electroluminescent

Allows pigments.

FIG. 3 shows a schematic illustration of an electrode 6 and of a value or security document 2. In this case, the electrode 6 is arranged relative to the value or security document 2 in such a way that an emission direction 9 of an excitation field 7 generated by the electrode 6 is perpendicular to a surface 15 of the value. or security document 2 is oriented. On the surface 15, a security element 16 is arranged, which comprises electroluminescent pigments (not shown). These can be excited by the electric excitation field 7 such that they emit a luminescence radiation 17. By the physical

Formation of the electrode 6 results in the area of the security element 16 a region with a high electrical flux density of the excitation field 7. If an electroluminescent pigment is arranged in this region, then this electroluminescent pigment can also be excited, if comparatively lower

Excitation voltages, for example, with amplitudes between 100 V and 5 kV can be used.

In Fig. 4 is a schematic arrangement of a value or security document 2 with a security element 16 which on a surface 15 of the value or

Security document 2 is arranged, and an electrode assembly 18 shown. The electrode assembly 18 includes a plurality of electrodes 6, the emission directions 9 are parallel to each other. Each of the electrodes 6 generates an unillustrated one

Excitation field 7 (see, for example, Fig. 2a), which is formed according to the explanations made to Fig. 2a. All electrodes 6 are electrically contacted together, wherein in Fig. 4, a transformer 5 is shown, the output voltage, ie the excitation voltage, is applied simultaneously to all electrodes 6.

FIG. 5 shows a plan view of the electrode arrangement 18 shown in FIG. 4. Here it is shown that the individual electrodes 6 are arranged in the form of tufts or bundles. In this case, a distance and a direction to a respectively adjacent electrode 6 between the individual electrodes 6 vary. Thus, a random spatial arrangement of the electrodes 6 results, which also causes a random spatial distribution of regions with high or maximum flux density of the excitation field 7.

The electrode arrangement shown in FIG. 5 advantageously increases an excitation area and thus also a light emission area of the security element 16 (see, for example, FIG. 4). In order to minimize wear, an electrode 6 or all electrodes 6 of the electrode arrangement 18 can be cast in a plastic material, in particular in a high-voltage-resistant and well-insulating plastic material, For example, in a UV-curing epoxy potting, a 2k epoxy potting, a silicone potting, a thermoplastic polyurethane (TPU) molding or an injection molding polymer material potting shed. This advantageously avoids the formation of corona formation at tips of the electrodes 6, at the same time minimizing wear.

FIG. 6 shows a plan view of a further advantageous electrode arrangement 18. In this case, electrodes 6 of the electrode arrangement 18 are arranged such that the electrodes 6 comprise a region 19, a recess 20 being arranged in this region 19. The region 19 can be, for example, a region 19 enclosed by a connecting line 22 of the electrodes 6. The

The connecting line 22 of the electrodes 6 may in this case be e.g. be circular. Thus, the electrodes 6 are arranged on a circular line with a predetermined distance to each other, wherein the circle has a predetermined radius. Of course, other forms of arrangement are conceivable, for example on a rectangular connecting line.

The recess 20 or opening may e.g. as a blind hole or as

continuous, so two-sided open, bore be formed. The recess 20 may be cylindrical. For example, an axis of symmetry of the

Connecting line 22 and the cylindrical recess 20 are aligned.

The recess 20 may serve as an optical detection channel or form an optical detection channel, through the recess 20 radiation, e.g. radiation emitted by an excited electroluminescent pigment, to an optical detection device 21 (see FIG. 7) or to an eye of a user.

Thus, it follows that the electrodes 6 are arranged around the optical detection channel. This allows both the excitation and the detection of the emitted light from only one common side, e.g. of the value or

Security document 2, can be done.

In Fig. 7 is a schematic representation of that shown in Fig. 6 Electrode assembly 18 and a value or security document 2 shown.

It can be seen that the electrode assembly 18 or a housing of the

Electrode assembly 18 is formed in a hollow cylinder, wherein in one

Sheath portion 23, the electrodes 6 arranged, for example, shed are. On a bottom surface 24 of the inner volume of the hollow cylinder, which forms the recess 20, an optical sensor 21 is arranged.

A security element 16 of the value or security document 2, which contains electroluminescent pigments (not shown), is charged with an excitation field 7 (see, for example, Fig. 2a), one of which is a radiation direction 9 of the

Electrode 6 generated excitation field 7 is oriented perpendicular to a surface 15 of the value or security document 2. The electroluminescent

Luminescent radiation emitted pigments passes through the recess 20 in the detection range of the optical sensor 21st Of course, it is possible that 20 optical elements, for example, for beam guidance or bundling, for example, a lens, are arranged in the serving as an optical detection channel recess. The optical sensor 21 may be, for example, a photodiode with a downstream amplifier. The illustrated embodiment advantageously results in a structurally very compact design of a document checking device, in particular a portable document checking device.

The inverter 4 shown in Fig. 1 may be implemented, for example, as an oscillator circuit which is e.g. an operational amplifier circuit and two FET as push-pull output stage. The transformer 5 may, for example

Include transformer coils that are wound on a ferrite core. For example, the electrode 6 can only be connected to a lead of the circuit shown in Fig. 1, e.g. a turn of a coil of the transformer 5, are connected. Preferably, the circuit shown in Figure 1 is operated with excitation frequencies of the excitation field 7 (see, e.g., Figure 2a) greater than audible frequencies, for example frequencies between 30 kHz to 20 MHz, preferably in a range of 70 kHz to 100 kHz.

Claims

claims

1) Device for contactless excitation of at least one electroluminescent pigment, in particular in a value or security document (2), wherein the device (1) comprises at least one electrode (6),

wherein the at least one electrode (6) is formed such that an electrical flux density of the of the electrode (6) in a predetermined

The device (7), the device having a plurality of electrodes (6), wherein each of the electrodes (6) is formed such that the electrical flux density of the one of an electrode (6) in a predetermined emission direction (9 ) producible field (7),

characterized in that

all electrodes (6) have a common emission direction.

2) Device according to claim 1, characterized in that in a

predetermined area (13) of a cross-sectional plane (12) oriented perpendicular to the predetermined radiation direction (9) of the electrode (6) changes an electric flux density, wherein the predetermined area (13) of the entire or a predetermined portion of the Electrode (6) generated electric field (7) is penetrated.

3) Device according to claim 2, characterized in that in at least a portion of the predetermined area (13) of the cross-sectional plane (12), the electrical flux density is higher than in other portions of the predetermined area (13).

4) Device according to one of claims 1 to 3, characterized in that the at least one electrode (6) tapers towards a radiation-side end.

5) Device according to claim 4, characterized in that the electrode (6) has a conical or conical portion.

6) Device according to one of claims 1 to 5, characterized in that the electrode is designed as a wire. Device according to one of claims 1 to 6, characterized in that a distance of an electrode (6) to an adjacent electrode (6) is less than or equal to a predetermined maximum distance.

Device according to one of claims 1 or 7, characterized in that a plurality of electrodes (6) are electrically contacted together.

Method for contactless excitation of at least one electroluminescent pigment, in particular in a value or security document (2), wherein an alternating electrical voltage is applied to at least one electrode (6), wherein the at least one electrode (6) is designed such that an electric Flux density of the electrode (6) in a predetermined

Wherein a non-contact excitation device (1) has a plurality of electrodes (6), each of the electrodes (6) being designed to increase the electrical flux density of the electrode (6) ) field (7) generated in a predetermined emission direction (9),

characterized in that

all electrodes (6) have a common emission direction.