WO2005116941A1

WO2005116941A1 - Device for verifying the authenticity of a valuable document or security document

Info

Publication number: WO2005116941A1
Application number: PCT/EP2005/001568
Authority: WO
Inventors: Manfred Paeschke; Anett Bailleu
Original assignee: Bundesdruckerei Gmbh
Priority date: 2004-05-07
Filing date: 2005-02-16
Publication date: 2005-12-08
Also published as: EP1743305B1; DE102004022752B4; SI1743305T1; CY1117500T1; DE102004022752A1; ES2567059T3; EP1743305A1

Abstract

The invention relates to a device for verifying the authenticity of a valuable document or security document with means (208, 210, 214) for measuring an electrical signal (216), which depends on a dielectric property of the valuable or security document, and with means (218) for comparing the signal to a reference signal (222).

Description

Device for checking the authenticity of a value or security document

The present invention relates to a device for checking the authenticity of a value or security document and to a digital storage medium, in particular a computer program product.

Various value and security documents and devices for checking the authenticity of value or security documents are known from the prior art.

DE 3840729A1 discloses a multi-layer recording medium, in particular an identification card, in which an outer color layer has a first color and an inner color layer has a second color. DE 19836813A1 discloses a value and security document with optically stimulable dyes for checking the authenticity. The dyes are embedded in a carrier material and, together with the carrier material, form a laser-active element.

From DE 412651 A1, a security document with an embedded areal security element (security thread) is known, which is constructed in multiple layers and has electroluminescent properties.

From US-A 4355300 a test device for the mechanical authenticity check of a security document is known, an AC voltage being applied to an electrode arrangement for carrying out the security check.

EP 1059619B1 discloses an arrangement for the visual and mechanical authenticity check of value and security documents based on an electromagnetic excitation of electroluminescent properties.

A corresponding value and security product with luminescent security elements is known from EP 0964791 B1.

From US-A 4218674 a method for checking the authenticity of a document is known in which magnetic particles are embedded. The check is carried out using a magnetic read head.

In contrast, the invention is based on the object of creating an improved device for checking the authenticity of a value or security document and a corresponding digital storage medium, in particular a computer program product.

The objects on which the invention is based are each achieved with the features of the independent claims. Advantageous embodiments of the invention are specified in the dependent claims.

The device according to the invention serves to check the authenticity of a value or security document which has a dielectric property, in particular dielectric particles. The dielectric particles can be in or multiple layers in or on the value or security document. For example, the dielectric particles in different layer thicknesses are printed on or in the value or security document using different printing methods, for example by means of offset printing or steel engraving. Alternatively, the dielectric property is not realized by dielectric particles, but rather by dielectric material of the value or security document.

The distribution of the dielectric material or the dielectric particles in / or on the value or security document forms the basis for checking the authenticity by means of the device according to the invention. For this purpose, an electrical signal is measured, which is dependent on the dielectric properties of the value or security document. This signal is compared to a reference signal. If the measured electrical signal and the reference signal agree sufficiently, the value or security document is rated as genuine.

According to a preferred embodiment of the invention, the device has means for generating an electrical field for penetrating the value or security document at least in a partial area. At least one electrode for field generation is preferably provided for this.

According to a preferred embodiment of the invention, the electrical signal depends on the electrical capacitance formed from the at least one electrode and the value or security document. The electrical field preferably only penetrates a partial area of the value or security document. When the value or security document moves through this field area, a time-varying electrical signal is obtained which is compared with a corresponding reference signal in order to check the authenticity of the value or security document.

According to a preferred embodiment of the invention, the electric field is generated by two opposite electrodes which form a gap for receiving a partial area of the document of value or security. In this area, the value or security document is penetrated by the electrical field, so that an electrical capacitance resulting from the dielectric particles of the value or security document located in the partial area results. According to a further preferred embodiment of the invention, an essentially planar electrode arrangement is provided on one side of the value or security document.

According to a further preferred embodiment of the invention, the device has a drive for the relative movement of the value or security document and the electrical field. The drive and thus the transport speed of the value or security document along the field-generating electrode is preferably regulated as a function of the measured electrical signal.

According to a further preferred embodiment of the invention, the value or security document has a luminescent, in particular an electroluminescent, property. The luminescent property is advantageously excited by the electric field, which is also used to measure the signal dependent on the electrical capacitance. The luminescent property can be checked visually, for example through a viewing window of the device. Alternatively or additionally, the check is carried out electronically, for example by recording the luminescence using an optical sensor and comparing the corresponding signal with a reference signal.

For example, the dielectric particles of the value or security document also have electroluminescent properties. As such dielectric particles with electroluminescent properties, inorganic pigments of generally II-VI compounds, such as ZnS, CaS, CdS, ZnSe, ..., but also SiC or GaAs are preferably used. To improve the electrical properties of these inorganic pigments, these can be combined with dielectric materials by means of complete or partial microencapsulation. Alternatively or additionally, organic polymers with electro-optical properties, for example thianthrene polymers, can be used as dielectric particles of the value or security document. The distribution of the dielectric particles with the electroluminescent properties in and / or on the value or security document therefore results in a double security feature, which is checked by measuring the total electrical capacitance formed with the electrode arrangement of the device and the luminescence signal emitted by the excitation of the electric field can be. It is particularly advantageous that no separate optical means are required to excite the luminescence.

According to a preferred embodiment of the invention, the electrode arrangement for generating the electrical field is essentially symmetrical and planar. On the opposite side of the planar electrode arrangement, an optical sensor is preferably arranged on an axis of symmetry of the planar electrode arrangement. The value or security document is drawn through the gap formed between the optical sensor and the planar electrode arrangement, both security features, i.e. the electrical capacitance profile and the profile of the luminescence, being checked when the value or security document moves through the gap.

According to a preferred embodiment of the invention, the device has a user interface for outputting an acoustic, visual and / or tactile signal for displaying the result of the authenticity check. The electrical signals, which are dependent on the distribution of the dielectric particles, are preferably evaluated by a logic circuit which, if there is sufficient agreement with the corresponding reference signals, outputs a logic signal signaling the authenticity of the value or security document to the user interface.

Preferred embodiments of the invention are explained in more detail below with reference to the drawings. Show it:

FIG. 1 shows a schematic, perspective illustration of a banknote with dielectric particles and materials, Figure 2 is a block diagram of an embodiment of the device according to the invention.

FIG. 3 shows a block diagram of a further embodiment of the device according to the invention,

FIG. 4 shows an embodiment of the device according to the invention with a measuring bridge,

FIG. 5 shows an embodiment of the device according to the invention with a logic circuit,

FIG. 6 shows an example of a signal curve in the device in FIG. 5,

FIG. 7 shows a block diagram of a further embodiment of the device according to the invention,

FIG. 8 shows a flow diagram of a preferred mode of operation of the device of FIG. 7.

FIG. 1 shows a schematic or perspective view of a value or security document 100, which in the example case considered here is a bank note. Document 100 has a substrate 102 with a specific dielectric constant ε ₁ .

On the document 102 there is an imprint 104 with dielectric particles with a dielectric constant ε ₂ . Another print 106 on the document 100 has a dielectric constant ε ₃ . There is also a kinegram, hologram or sticker 108 on the document 100 with a dielectric constant ε ₄ . Inside the document 100 there is an inclusion 110 with a dielectric constant ε _s . There is an embossment 112 on the surface of the document 100, which is filled with a material with a dielectric constant ε ₆ . Furthermore, the dielectric material of the substrate 102, the imprint 104, 106, the sticker 108, the insert 110 and / or the embossment 112 have electroluminescent properties.

The embodiment of a device 200 according to the invention shown in FIG. 2 can be used to check the authenticity of the document 100. A pair of rollers is formed by the opposing rollers 202 and 204 of the device 200, through which the document 100 is driven in the direction of the arrow 206.

The device 200 has an electrode arrangement which, in the exemplary embodiment considered here, consists of the electrodes 208 and 210 lying opposite one another. The electrodes 208, 210 are used to generate an electrical field 212 which penetrates the document 100 in a partial area.

The electrodes 208, 210 are connected to a measuring circuit 214, which emits an electrical signal 216 which is dependent on the dielectric properties of the partial area of the document 100 located in the region of the electrical field 212. A comparator 218 is connected to the measuring circuit 214 and a reference memory 220, from which the comparator 218 receives a reference signal 222.

The comparator 218 compares the signal 216 with the reference signal 222 and, as a result of the comparison, outputs a logic signal 224 to a user interface 226. For example, the logic signal 224 has three different logic values: a first logic value, for example 01, which is output if the signal 216 corresponds sufficiently with the reference signal 222, a second logic value, for example 00 if the signal 216 does not sufficiently corresponds to the reference signal 222, and a third logical value, for example 11, if no clear statement is possible.

The user interface 226 has a red light-emitting diode 228, a yellow light-emitting diode 230 and a green light-emitting diode 232. When the user interface 226 receives the signal 01 from the comparator 218, the green light-emitting diode 232 is activated, upon receipt of the signal 00 the red light-emitting diode 228 and when signal 11 is received, the yellow LED 230. FIG. 3 shows a further embodiment of the device 200. Elements of the embodiment of FIG. 3 which correspond to elements of FIG. 2 are identified by the same reference numerals. In contrast to the embodiment in FIG. 2, in the embodiment of the device 200 in FIG. 3, the electrodes 208 and 210 are arranged next to one another on the same side of the document 100. The corresponding course of the electric field 212 is shown in FIG. 3.

The electrical field 212 excites the electroluminescence of the electrical particles of the document 100 insofar as they have electroluminescent properties and are located in the partial area of the document 100 which is penetrated by the electrical field 212. The electroluminescent radiation 234 thereby excited can pass through a viewing window 236, which is arranged on the side of the document 100 opposite the electrodes 208, 210, so that a user of the device can visually check the corresponding security feature through the viewing window 236. For example, a certain pattern or motif must appear in the viewing window 236 if the document 100 is genuine.

FIG. 4 shows an embodiment of the measuring circuit 214 of FIG. 3

Measuring circuit 214 has an impedance measuring bridge 238, preferably a capacitance measuring bridge, for measuring that through the document 100 and the electrodes

208, 210 formed complex impedance Z _x . In particular, goes into the complex

Impedance Z _{x is} the capacitance C _{x of} the arrangement formed by the electrodes 208, 210 and the document 100, which depends on the local dielectric properties of the document 100.

The signal supplied by the impedance measuring bridge 238 is amplified by means of an amplifier 240, so that the signal 216 (cf. FIG. 3) is obtained. The further elements of the device 200 are not shown in the figure for the sake of clarity.

FIG. 5 shows a digital circuit 242 for determining the signal 216. Elements in FIG. 5 which correspond to elements in the preceding figures are again identified by the same reference symbols. The resulting capacitance of the electrodes 208, 210 under the influence of the document 100 is CBN in FIG designated. The digital circuit 242 has a reference capacitance 244 CREF. The capacitance CREF is of the order of magnitude of the capacitance of the electrode arrangement under the influence of only the substrate 102 (cf. FIG. 1) of the document 100.

The digital circuit 242 also has the multivibrators (astable multivibrators) M1 and M2. The multivibrator M1 is controlled by CB _N and synchronized by the multivibrator M2. The Multivibrator M2 is controlled by CREF. The output signals Ui and U _{2 of} the multivibrators M1 and M2 are linked to one another via the logic gate 246 and the output signal U _{3 of} the gate 246 is smoothed by means of the low-pass filter (TP) 248, so that the signal 216 is obtained.

FIG. 6 shows the time course of the signal voltage pulses of the signals U-ι, U ₂ and U ₃ of FIG. 5, for example on the condition that CBN is currently larger than CREF.

FIG. 7 shows a further preferred embodiment of the device 200. Elements in FIG. 7 which correspond to elements in the previous figure are again identified by the same reference numerals.

In contrast to the embodiment in FIG. 3, an optical sensor 250 is arranged above the electrodes 208 and 210 alternatively or in addition to the viewing window. This can be a photodiode, a photomultiplier or a CCD-based sensor. The optical sensor 250 is connected to a measuring circuit 252, which supplies a signal 254. The luminescence radiation 234 is detected by the optical sensor 250 and evaluated by the measuring circuit 252. Accordingly, the signal 254 is representative of the luminescent radiation 234. This can be a single signal value or complex image information. The optical sensor 250 is preferably arranged on the axis of symmetry 268 of the electrodes 208, 210.

A comparator 256 receives a reference signal 260 from a reference memory 258 and the signal 254 from the measuring circuit 252 in order to compare the signal 254 with the reference signal 260. The mode of operation of the comparator 256 can be similar to that of the comparator 218. The comparator 256 can be an image processing unit that compares reference image data supplied by the reference memory 258 with the image data of the signal 254. If the comparator 256 determines a sufficient match, it outputs a corresponding signal 262 to the logic circuit 264, which also receives the signal 224 from the comparator 218.

The signal 262 has, for example, the value 01 if the signal 254 agrees sufficiently with the reference signal 260, the value 00 if such an adequate match does not exist, and the value 11 if no clear statement is possible.

The logic circuit 264 combines the signals 224 and 262 with one another in order to control the user interface 226 accordingly. For example, the green light emitting diode 232 is activated when both the signal 224 and the signal 262 have the value 01. In contrast, the red light-emitting diode 228 is activated when one of the signals 224 or 262 has the value 00. The yellow light-emitting diode 230 is activated when none of the signals 224 or 262 has the value 00, but at least one of the signals 224 or 262 has the value 11.

The change in the signals 224 and 262 received by the logic circuit 264 is representative of the speed of movement of the document 100 by the roller pair 202, 204. Accordingly, the drive speed can be controlled by the logic circuit 264 by driving the motor 266 which drives the roller pair 202, 204 in order to set or adjust this to maintain a target movement speed.

The functionality of the comparators 218 and / or 256 and / or that of the logic circuit 264 can be implemented by a corresponding computer program that is executed by a microprocessor of the device 200. The computer program can be stored as a computer program product on a digital storage medium, for example on a non-volatile memory of the device 200 as firmware or on another data carrier. FIG. 8 shows a corresponding flow chart. In step 800, the value or security document is inserted or introduced into the device according to the invention. For example, the device has a corresponding slot for this purpose, for example in the case of payment machines with a banknote feeder. In step 802, the drive for feeding the document is started. In step 804, an electric field, preferably an alternating electric field, is switched on in order to measure a capacitance caused by the local dielectric properties of the document and to excite electroluminescence.

In parallel steps 806 and 808, an optical signal for detecting the electroluminescence and a capacitance-dependent signal for detecting the local dielectric properties are measured accordingly. In step 810, the two signals are evaluated. If the optical signal matches an optical reference signal and the capacitance-dependent signal matches a capacitance reference, the document is considered authentic (step 814). In this case the document is accepted.

Otherwise (step 812), acceptance of the document is refused. For example, the drive is operated in the opposite direction so that the document is pushed out of the device again. This embodiment is particularly advantageous for a payment machine.

LIST OF REFERENCE NUMBERS

100 document

102 substrate

104 imprint

106 imprint

108 stickers

110 storage

112 embossing 200 device

202 roller

204 roller

206 direction of arrow

208 electrode

210 electrode

212 electric field

214 measuring circuit

216 signal

218 comparators

220 reference memories

222 reference signal

224 logic signal

226 user interface

228 light emitting diode

230 light emitting diode

232 light emitting diode

234 radiation

236 viewing window

238 impedance measuring bridge

240 amplifiers

242 digital circuit

244 reference capacity

246 gates

248 low pass 250 optical sensor

252 measuring circuit

254 signal

256 comparators 258 reference memories

260 reference signal

262 logic signal

264 logic circuit

266 motor 268 axis of symmetry

Claims

Patent claims

1. Device for checking the authenticity of a value or security document with

Means (208, 210, 214) for measuring an electrical signal (216) dependent on a dielectric property of the value or security document,

Means (218) for comparing the signal with a reference signal (222).

2. Device according to claim 1, with means (208, 210) for generating an electrical field (212) for penetrating at least a portion of the value or security document.

3. Device according to claim 2, with at least one electrode (208, 210) for generating the electric field.

4. The device according to claim 3, with a substantially planar electrode arrangement (208, 210).

5. Apparatus according to claim 3 or 4, with opposite electrodes 208, 211), which form a gap for receiving at least a portion of the value or security document.

6. Device according to one of the preceding claims 3 to 5, wherein the electrical signal depends on the capacitance formed from the at least one electrode and the value or security document.

7. Device according to one of the preceding claims 2 to 6, with means (202, 204; 266) for the relative movement (206) of the electrical field and the value or security document.

8. The device according to claim 7, wherein the means for relative movement comprise an electric drive (266).

9. The device according to claim 8, with means (264) for controlling the drive as a function of the electrical signal (224; 262).

10. Device according to one of the preceding claims, with means (236, 250, 252) for detecting a luminescent property of the value or security document.

11. The device according to claim 10, wherein the means for detecting the luminescent property are designed for visual detection.

12. The apparatus of claim 10 or 11, wherein the means for detection comprise an optical sensor.

13. The apparatus of claim 10, 11 or 12, wherein the means for detecting the luminescent property are adapted to measure an electrical signal (254) dependent on the luminescent property, and with means (256) for comparing the electrical dependent on the luminescent property Signals with a reference signal (260).

14. Device according to one of the preceding claims 10 to 13, wherein the means for generating the electric field are designed to excite the luminescent property.

15. Device according to one of the preceding claims 3 to 14, wherein the at least one electrode (208, 210) and the optical sensor (250) form a gap for receiving at least a partial area of the value or security document.

16. Device according to one of the preceding claims, with a substantially symmetrical planar electrode arrangement (208, 210) for generating the electrical field (212), the optical sensor (250) being arranged essentially on an axis of symmetry (268) of the planar electrode arrangement is.

17. Device according to one of the preceding claims, wherein the means for measurement comprise a bridge circuit (238).

18. Device according to one of the preceding claims, wherein the means for measurement have a resonant circuit.

19. Device according to one of the preceding claims, wherein the means for measurement comprise a digital circuit (242).

20. Device according to one of the preceding claims, with a user interface (226) for outputting an acoustic, visual and / or tactile signal for outputting a result of the authenticity check.

21. The apparatus of claim 17, with a logic circuit (264) for outputting the signal via the user interface if the electrical signal dependent on the dielectric property (216) with its reference signal (222) and / or the electrical dependent on the luminescent property Signal (254) with its reference signal (260) match sufficiently.

22. Digital storage medium, in particular a computer program product, for checking the authenticity of a value or security document (100), with program instructions for

Detection of an electrical signal (216) dependent on a dielectric property of the value or security document,

- Comparison of the signal curve of the electrical signal with a reference curve (222),

- Output of an authenticity signal (224) indicating the authenticity if the signal curve sufficiently matches the reference curve.

23. Digital storage medium according to claim 22, with further program instructions for Detection of a further electrical signal (254) dependent on a luminescent property of the value or security document,

Comparison of the course of the further electrical signal with a further reference course (260),

wherein the signal indicating the authenticity of the value or security document is only output if the further signal curve also corresponds sufficiently with the further reference signal.