EP1179812A1 - Device and method for testing documents of value - Google Patents

Abstract

Electrode arrangement with a number of rectangular electrodes (9.1-9.8) encapsulated by an electrode (10) of a second type for testing banknotes. Independent claims are made for a (1) a method for testing banknotes in which the notes are moved across the electrodes in a direction perpendicular to their transport direction (2) a banknote recognition device (3) a banknote testing device Capacity differences between the electrodes are used to provide a capacity pattern for the scanned in note that is then processed to identify the banknote, any characteristics and defects.

Description

Technical field

The invention relates to an electrode arrangement with a plurality of electrodes, one Recognition device and a method for checking a security and a Security testing device with a transport device for transporting a Security along a transport path.

State of the art

In many places where banknotes or other securities in large quantities the securities are examined or processed. Here will on the one hand the authenticity of a security is checked and / or for example the Value of a banknote detected. A banknote can also be used, for example "Fitness test" (if the banknote is defective, adhesive tapes are stuck on somewhere, stuck a staple somewhere, etc.) to see if it comes out of the Traffic is to be drawn and replaced by a new banknote. It is further possible to determine whether two or more banknotes stick together, for example what is important when counting banknotes.

Devices are known with which one or a few such tests can be carried out can be carried out.

From DE 296 04 504 U1, for example, a test device is known with which Security documents that have an electrically conductive security thread taking advantage of the principle of capacitive coupling between transmit and Receiving antennas can be examined for their authenticity. The device has for this purpose, for example, a plurality of strip sensors.

Another device for identifying documents is from WO 97 30 422 A1 known. Your detection unit can be magnetic, optical, electrical, for example comprise conductive or capacitive sensors, each for detection various features of a document can be used individually or are arranged in arrays.

However, these devices have the disadvantage that with a sensor or Sensor type only one characteristic feature of the security under test can be tested. So to check a variety of properties, you need to different types of sensors can be installed. As a result, they don't just claim a lot of space, but are also complicated to control and expensive to manufacture.

Presentation of the invention

The object of the invention is a device and a method of the aforementioned Specify the type that avoid the problems existing in the prior art and in particular a simple and reliable check of a plurality of characteristic ones Enable properties of securities.

The solution to the problem is device-wise by the features of claims 1 and procedurally defined by the features of claim 9. According to the invention the electrode arrangement comprises a plurality of electrodes and is two-dimensional educated. By two-dimensional is meant that the electrodes, for example in the Contrary to the plates of a plate capacitor arranged opposite one another, as in surfaces arranged side by side on a common plane are formed. The Electrode arrangement includes two types of electrodes. On the one hand a plurality of first electrodes and on the other hand at least one second electrode, the at least a second electrode is designed such that it at least the first electrodes partially surrounds.

Any security, i.e. H. each type of security has its own individual capacity pattern. This can be influenced by many factors. So z. B. by type, position, size and material (e.g. dielectric constant) of the built-in security features such as Security thread, kinegrams, magnetic colors etc., but also by material and Size of the paper used. With a single sensor that the inventive Has electrode arrangement, can thus have a plurality of security features Securities are checked, with corresponding recognition devices or whole Test devices are small, light and inexpensive to manufacture.

The specific design of the electrodes can be very diverse. You are like that shaped and arranged that the second electrode, for example, the first electrodes L-shaped or U-shaped surrounds or completely encloses them. Preferably there is second electrode from a single surface, which is also divided into several individual electrodes, which may be connected to each other, can be divided. Is conceivable also that the second electrode is only on one side of the first electrodes extends, for any measurement any of the first electrodes to the potential the second electrode can be switched. From this it follows that the electrode to be measured is partially surrounded by the other electrodes.

As already mentioned, all electrodes are in a common plane, the The term plane should not be understood as a geometric plane, but rather as a surface should. That is, the electrode plane can also have a slightly curved surface, for example the Surface of a cylindrical roller, over which the banknote to be checked is passed becomes.

In principle, the geometry of the electrode surfaces of the first electrodes and their arrangement freely selectable. However, it is advantageously adjusted to the position of the securities, if they are guided past the electrode arrangement. With most test fixtures the securities will cross the transport path along the transport path guided. With the fewest possible first electrodes, the largest possible area of the securities can be checked, they are therefore preferably at right angles to the direction of transport arranged side by side in at least one row. For the sake of simplicity they are preferably rectangular and each side by side in a particular one Distance aligned.

For the sake of simplicity, the first electrodes are arranged in a single row. For demanding applications, however, several, one after the other, can be used Rows are formed. This enables, for example, with correspondingly fast electronics a higher sampling rate in the direction of transport.

Because, in contrast to resistance or conductivity measurements, "only" the capacitance two electrodes are measured, apart from this simple arrangement of rectangular, electrodes placed next to each other are of course also more complex shapes the first as well as the second electrode or electrodes possible. For example the electrodes are comb-like or Z-shaped, S-shaped or spiral-shaped interlocking. Also rectangles with broken or otherwise shaped edges so that they are in in a row can be put together.

Furthermore, the electrodes can also be arranged in several rows one behind the other. The spacing of the rows can thus depend on the transport speed of the securities be coordinated that a higher resolution is achieved in the direction of transport becomes. For example, for two rows, the distance is chosen so that the distance from the rear Range measured exactly between the two measurements by the front row of measured areas. In addition, with several Rows through an offset arrangement of the rows also an increased resolution across Reach transport direction.

The number of first electrodes used depends on the necessary resolution. In a preferred embodiment of the invention there are at least two and a maximum of 256 first electrodes. As a rule, however, a resolution of 8 or 16 measuring points in the transverse direction is sufficient, which is why a particularly preferred embodiment has 8 or 16 first electrodes. The area of a first electrode is approximately between 10 mm ² and 500 mm ² . The smaller the area of a first electrode, the greater the resolution actually achieved when scanning a security. However, the absolute changes in capacity are also getting smaller. A preferred value for the area of a first electrode is approximately 200 mm ² . The distance between two first electrodes is between 0.1 mm and 10 mm, a distance of approximately 1 mm being preferred. This distance corresponds approximately to the size of the smallest security feature to be resolved, the security thread.

This value also applies to the distance between the second electrode and the first electrodes. As already mentioned, the second electrode is also flat, wherein its surface has a hole in which the first electrodes are located. In the case of rectangular first electrodes arranged next to one another, this is Hole also rectangular.

Instead of keeping the spacing of the electrodes the same everywhere, they can be at different locations Positions can also be of different sizes. This could be the distance between the first electrodes 1 mm below each other and the distance between the first electrodes and the second electrode larger, for example 2 mm, can be selected. Or the distance of a first electrode the second electrode is larger on one side than, for example, on the opposite Page.

The electrode arrangement is preferably on a main surface of a plate-shaped one Applied substrate. This substrate is essentially one, for example rectangular circuit board with a width of about 2 to 3 cm and one Length that is chosen to be somewhat longer than the length of a security to be checked. The individual electrodes are made of electrically conductive material, for example Copper, and are attached to one side of this circuit board. The application of the electrodes can be easily integrated into the PCB manufacturing process in this case become.

The electrodes can also be placed on any (advantageously electrically insulating) carrier material, for example, a cuboid or a roll made of non-conductive plastic become. This cuboid or role would then be on the transport path accordingly attached so that a banknote to be checked would be passed.

The substrate used has a thickness between 0.1 mm and 10 mm. Is the substrate too thin, it can bend undesirably, resulting in a the security to be tested can no longer be guided flat past the electrode arrangement can. However, this can falsify the measurement results. However, the substrate is closed thick, the device becomes too heavy and unwieldy. The substrate thickness is preferred between 1 mm and 2 mm.

The substrate is preferably made of dielectric material. This should have a comparatively low dielectric constant ε _r , so that the energy density of the electric field is highest above the electrodes and not in the substrate. The dielectric constant ε _{r of} the substrate is advantageously less than 10 and is preferably in the range between 3 and 5.

The measuring unit and the control unit can be used as a separate module or modules, For example, as a separate circuit board, realized and with cables or other lines be connected to the electrode arrangement. Or they become part of another Module, for example a central control unit, which the entire test device controls, trained. Of course, there is also a logical or local division multiple modules possible.

So that the detection unit and thus the test device is as small and small as possible can be made compact, the control unit and the measuring unit are preferred on the side opposite the electrode arrangement (the rear side) of the plate-shaped Substrate provided. Control and measuring unit are for example electrical or electronic components formed, which by means of known manufacturing processes on the back of the circuit board.

For controlling the electrodes and for powering the individual components a large number of electrical connections are required. The substrate is therefore an advantage Multi-layered and has, for example, several, by insulating layers separate, conductive layers, with targeted electrical connections between the individual layers are present. Such connections typically exist of holes in the substrate coated with electrically conductive material, which the connect the corresponding layers with each other. So that the first electrodes have no asymmetries due to different perforation, the substrate will not completely pierced, but the holes are only down to the one directly below Layer drilled.

The conductive layers include, for example, a supply layer in which the Supply voltages are carried, a signal layer in which the measurement signals and other signals are carried and an electrode layer with the first and the second electrode on the front and a component layer on the back of the Substrate on which the electronic components are applied and connected to each other become.

To carry out the measurements, the two involved in the measurement are used Electrodes, for example a first electrode and the second electrode, with the measuring unit connected, being one of these two electrodes, generally it will be the second Be electrode, for example, is placed on ground. The other electrode, however, is no longer connected. Then the capacitance of the "floating" first electrode measured against the second electrode.

The (first) electrodes not involved in the measurement can also be "floating" be switched. However, as has been found, it is beneficial if these electrodes switched to a predetermined, stable voltage potential during a measurement become. Without this measure, the measured signals show an increased Noise component. For this reason, the detection device is designed accordingly. For example, if the capacitance is between a first and a second electrode All other first electrodes can be measured to a predetermined value Voltage potential, especially to ground.

Of course, it is also possible to apply the electrodes that are not involved in the measurement to switch another, stable voltage potential.

As already mentioned, a security testing device with a detection device of the type just described on a transport device with which to be tested Security can be transported along a transport path. The transport path leads past the electrode arrangement of the recognition device, the security is pressed against the electrode arrangement by means of rollers, for example.

While making the desired measurements, i.e. H. while the security is on the electrode arrangement is guided past, the measuring unit can be sequential or simultaneous be connected to each individual electrode, the capacity of each two electrodes connected to the measuring unit is measured. In this way, a Capacity patterns of the security to be tested are determined.

Depending on the design of the measuring unit, i.e. H. depending on the number of available Measuring arrangements, several measurements can be carried out simultaneously, for which purpose a corresponding number of electrodes must be connected to the measuring unit.

In order to save space and costs, only one measuring arrangement is advantageously provided, which is why the measurements are carried out with the aid of multiplexing. The control unit takes over the control of the electrodes and ensures that at the right moment the correct electrodes are connected to the measuring unit.

For further properties of a test object that cannot be measured with the electrode arrangement To be able to determine securities advantageously includes the securities testing device further, additional sensor arrangements such as optical detectors for precise Determination of the angular position and the lateral displacement of the security compared the transport path. The angular position and the lateral position are important in that than they allow the absolute position of the security features on the device under test to determine.

Of course, sensors can also be used with which on magnetic, electrical or any other base characteristic features of the securities can be detected. The measurement results of such sensors can also be used Control of the measurements carried out with the electrode arrangement or to support them be used.

In the method according to the invention for checking securities, in which a testing security transported along a transport path and on an electrode arrangement is passed by with a plurality of electrodes, using a Control unit and a measuring unit determines a capacity pattern of the security, while passing the electrode assembly.

The capacity pattern is created both in the transport direction and across it performed a plurality of capacity measurements. This corresponds in the transverse direction Resolution of the number of first electrodes, with the capacitance for each capacitance measurement is measured between a first electrode and the second electrode. The resolution in the longitudinal direction depends on the transport speed and the measuring frequency, with which repeats the capacitance measurements per first electrode. The higher the Measurement frequency, the more measurements are made in the time in which the security is on the Electrode arrangement is guided past, possible for each security.

In order to obtain reliable measurement results, the electrode arrangement is made before the capacitance measurements preferably calibrated. Calibration is either done for a single one Electrode or for several or all electrodes, this being either simultaneously for can be done all or for each electrode separately.

There are various ways of measuring the capacitance between two electrodes. For example, the RF oscillator method, the charge compensation method or the Charge transfer method.

Measurement methods based on the charge transfer method are preferred used because they enable inexpensive circuits for precise capacitance measurement. In this method, a load of known size, for example one Capacitor with known capacitance, transferred to the capacitance to be measured. From the voltage occurring between the electrodes of the capacitance to be measured then the unknown capacity or the change in capacity compared to one determine previous measurement.

To carry out a capacitance measurement, two electrodes are used with the Measuring unit connected. One of the first electrodes and the second one are preferably Electrode electrically connected to the measuring unit. Then the capacity or their change measured and the measurement result temporarily stored or on passed the control unit.

As already mentioned, several can be used using several measuring arrangements Measurements can be carried out simultaneously. In this case, not just one, but accordingly, several first electrodes are connected to the measuring unit. Since the second electrode is also involved in every measurement, it can also be fixed with the Measurement unit are wired.

With such a measurement, the remaining electrodes also have an influence on the measured values. For example, they cause a disturbing noise in the measured Signal. To minimize this noise or other disturbing influences the electrodes not involved in the measurement preferably to a predetermined voltage potential connected. For example, this can be the same potential to which one of the two electrodes involved in the measurement is connected. For example becomes the second electrode and the first electrodes not involved in the measurement grounded during measurement.

Depending on the design of the measuring unit, one or more capacitance measurements can be made simultaneously be performed. With a complex and therefore rather expensive In a variant, the measuring unit has several measuring arrangements. For example, it would be ideal a number of measuring arrangements which corresponds to the number of first electrodes. This could mean that the capacitance of each first electrode compared to the second electrode be determined.

A preferred variant, which requires less hardware and therefore is cheaper, however, comprises only a single measuring arrangement. The single ones Electrodes are now used in succession to carry out the capacitance measurement Measuring unit connected. When measuring the capacities between a first one and the second electrode means that the first electrodes are multiplexed are connected to the measuring unit in the desired order, the second electrode is firmly connected to the measuring unit.

To, for example, when checking a banknote, a resolution of about 8 to 16 Measuring points transverse to the transport direction and about 15 to 30 measuring points in the transport direction to obtain the capacitance measurements are preferably at a frequency carried out in the order of 2 kHz. So multiplexing gets round a different first electrode is connected to the measuring unit every 2 milliseconds.

If several or more powerful measuring arrangements are used, the number of Measurements can be increased. That is, it can both increase the number of first electrodes as well as the measurement frequency can be increased. However, it should be noted that the absolutely measured capacitance values decrease with decreasing electrode area, which may require more sensitive measuring arrangements.

Many security features with specific electrical or magnetic properties such as different dielectric constants of the materials used can be checked in this way. Features that, on the other hand, are purely optical Are natural, but cannot be checked. In a preferred variant of the According to the method of the invention, the security to be tested is therefore on a passed additional sensor arrangement and the angular position and other features like the lateral shift of the security in relation to the direction of the transport path certainly. Of course, with such a sensor arrangement, too other optical properties of the security, in particular the position of a or several security features can be determined or the additional measurements used to check the measurements with the electrode arrangement.

From the following detailed description and the entirety of the claims there are further advantageous embodiments and combinations of features of the invention.

Brief description of the drawings

Fig. 1

Einen schematisch dargestellten Ausschnitt aus einer erfindungsgemässen Banknotenprüfvorrichtung;

Fig. 2

eine schematisch dargestellte Elektrodenanordnung zur Verwendung in der Vorrichtung aus Fig. 1;

Fig. 3

einen vergrösserten Ausschnitt der Elektrodenanordnung aus Fig. 2;

Fig. 4

eine schematisch dargestellte Platine mit aufgebrachter Elektrodenanordnung und weiteren bestückten Bauelementen als Steuer- und Messeinheit;

Fig. 5

das zur Fertigung der Platine aus Fig. 4 verwendete Multi-Layer Substrat;

Fig. 6

das Messresultat einer Elektrode beim Scannen einer einzelnen Banknote;

Fig. 7

das Messresultat einer Elektrode beim Scannen zweier Banknoten;

Fig. 8

eine schematisch dargestellte, zu prüfende Banknote bei Beginn des Scan-Vorgangs;

Fig. 9

das Messresultat einer Elektrode beim Scannen eines sechsteiligen Sicherheitsfadens einer Banknote;

Fig. 10

das Messresultat einer Elektrode beim Scannen einer Banknote;

Fig. 11

das Messresultat der gleichen Elektrode beim Scannen derselben Banknote mit einem Klebstreifen;

Fig. 12

das Messresultat einer Elektrode beim Scannen einer Banknote mit einem mit Korrekturflüssigkeit abgedeckten Bereich;

Fig. 13

das Messresultat einer Elektrode beim Scannen einer Banknote mit einer angehefteten Heftklammer;

Fig. 14

das Messresultat einer Elektrode beim Scannen einer in Längsrichtung geführten Banknote mit einem Kinegramm und einem Sicherheitsfaden und

Fig. 15

einen erfindungsgemässen Verfahrensablauf beim Prüfen einer Banknote.

The drawings used to explain the exemplary embodiment show:

Fig. 1

A schematically illustrated section from a banknote checking device according to the invention;

Fig. 2

a schematically illustrated electrode arrangement for use in the device of FIG. 1;

Fig. 3

an enlarged section of the electrode arrangement of FIG. 2;

Fig. 4

a schematically illustrated circuit board with an applied electrode arrangement and further equipped components as a control and measuring unit;

Fig. 5

the multi-layer substrate used to manufacture the circuit board from FIG. 4;

Fig. 6

the measurement result of an electrode when scanning a single banknote;

Fig. 7

the measurement result of an electrode when scanning two banknotes;

Fig. 8

a schematically shown banknote to be checked at the start of the scanning process;

Fig. 9

the measurement result of an electrode when scanning a six-part security thread of a banknote;

Fig. 10

the measurement result of an electrode when scanning a banknote;

Fig. 11

the measurement result of the same electrode when scanning the same banknote with an adhesive strip;

Fig. 12

the measurement result of an electrode when scanning a bank note with an area covered with correction fluid;

Fig. 13

the measurement result of an electrode when scanning a banknote with a staple attached;

Fig. 14

the measurement result of an electrode when scanning a bank note guided in the longitudinal direction with a kinegram and a security thread and

Fig. 15

an inventive procedure when checking a banknote.

In principle, the same parts are provided with the same reference symbols in the figures.

Ways of Carrying Out the Invention

With reference to Figures 1 to 15, in which an example of a test device or parts thereof are shown in detail, the invention will be described in more detail below. The Checking device is used in particular for checking banknotes, for example to determine the type and nominal value, to determine the condition (fitness test) and for the detection of counterfeits.

Figure 1 shows schematically a section of a banknote checking device 1. This can also perform other tasks such as saving or sorting the Take over banknotes. A bank note 2 to be checked is along a transport path 3 of a more or less complex system of rollers, belts, baffles etc. transported from an input slot to a note store (not shown). On A suitable unit of the transport system is a recognition unit 4, wherein before or after the recognition unit 4 on the transport path additional recognition units can be provided. A second detection unit 4.1 is shown, which is arranged in front of the recognition unit 4 in the transport direction.

The data on the banknote 2 collected by the recognition units 4, 4.1 are passed on to a central control 6 in the example shown via data lines 5.1, 5.2, which evaluates this data and carries out the actual check.

Transport systems for securities are known per se and are needed here not to be explained in more detail. In Fig. 1 four roles 7.1, 7.2, 7.3, 7.4 are exemplary shown, which feed the banknote 2 to the recognition unit 4 or then detect it and carry it away on the given transport path 3 in the desired direction. The roles for the recognition unit 4.1 are not shown. To one if possible The upstream and downstream pairs of rollers ensure reliable transport brought as close as possible to the detection units 4, 4.1. In addition there are 8 roles compared to the recognition unit 4 and a role 8.1 compared to the recognition unit 4.1 is provided, which presses the banknote 2 onto the respective recognition unit 4, 4.1. (The direction of rotation of the rollers is indicated by an arrow.)

Figures 2 (as an overview) and 3 (an enlarged section) show those in the recognition unit 4 used electrode arrangement. This is on the top of a board 12, which is mounted in the recognition unit 4 such that the banknote 2 is passed parallel to the electrode arrangement when they are checked. The electrode arrangement has 8 identical, rectangular, first electrodes 9.1 to 9.8, which are arranged side by side in such a way that their narrow sides are at a certain distance 13.1 in the order of z. B. 1 mm parallel to each other. Further points the electrode arrangement also has a rectangular, second electrode 10, which has a has rectangular recess 11 within which the first electrodes 9.1 to 9.8 are provided. The recess 11 is dimensioned such that the distance 13.2 between the edge of the recess 11 and a first electrode 9.1 to 9.8 the same everywhere is like the distance 13.1 between the first electrodes 9.1 to 9.8, i. H. about 1 mm.

FIG. 4 shows a cross section at AB through the circuit board 12. On the top the cross-section of the first electrode 9.5 and the second electrode 10 can be seen, which are drawn with thick lines for better visibility. The control unit and the measuring unit are in the form of electrical components on the Bottom of the board 12 realized. Some are examples, with common manufacturing processes on the circuit board 12, components 14.1 to 14.3 with their electrical connections shown.

FIG. 5 shows a cross section through the substrate 15 used to manufacture the circuit board 12. It consists of several electrically conductive or insulating layers. The substrate material used in the present example has a dielectric constant ε _r of about 4.3. The electrically conductive layers from top to bottom are: an electrode layer 15.1 with the electrodes 9.1 to 9.8 and 10, a supply layer 15.2 for producing the required supply lines (ground GND and supply voltage VCC), a signal layer 15.3 for distributing the signals to be transmitted and a component layer 15.4 for establishing further connections between the individual components. In between, differently thick insulating layers 16.1, 16.2, 16.3 are provided.

FIG. 8 shows the bank note 2 to be checked shortly after the start of the check. That is, the banknote 2 is guided in the direction of arrow 17 past the electrode arrangement, the distance between the bank note 2 and the electrode arrangement through the roller 8 (in FIG. 6 not shown) is kept to a minimum.

The banknote 2 has, for example, a kinegram 18 and one as security features Security thread 19, the security thread 19 partly in the paper of the banknote 2 is inserted so that only 6 small sections of the security thread are visible. As mentioned, the banknote checking device 1 is also used to carry out fitness tests suitable, which is why other features such as a staple attached to banknote 2 20, an area covered with correction fluid 21 and an adhesive tape 22 are shown. Since the features mentioned are on the recognition unit 4 facing side of the banknote 2, they are shown in dashed lines.

The following figures qualitatively show some measurement signals (or sections thereof), i. H. the change in capacitance between a first electrode 9.1 to 9.8 and the second Electrode 10, as can be measured when scanning banknote 2. On the The x-axis 23 is the time and the y-axis 24 the change in capacity. The Time Δt and the change in capacitance ΔC between two tick marks are e.g. T. different and specified in each case.

It should be noted that individual measurement points are not indicated in the figures as they are typically arise during multiplexing, but that the measurements as continuous Lines are given as a function of time.

Figure 6 (Δt = 50 ms, ΔC = 5 fF with fF = femto farad) shows the signal of the first electrode 9.6. The first electrode 9.6 sweeps over an area of the bank note 2 which does not have any special ones Features. The rise in the measurement signal is a consequence of the Banknote 2 paper generated capacity change.

FIG. 7 (Δt = 50 ms, ΔC = 5 fF) again shows the signal of the first electrode 9.6, where two banknotes 2 lie one above the other during the test. With optical sensors detecting such double notes is a difficult to impossible matter. With the inventive electrode arrangement, on the other hand, recognizes double notes easy, because the measurement signal shows, due to the two layers of paper, opposite a single note (see Figure 6) a significantly higher increase.

Figure 9 (Δt = 20 ms, ΔC = 10 fF) shows the signal of the first electrode 9.5. The first electrode 9.5 sweeps over the area of banknote 2 which comprises security thread 19. The rise in the measurement signal can be clearly seen. Even the 6th visible portions of the security thread 19 originating 6 measuring tips 25.1 to 25.6 recognizable.

Figures 10 and 11 (Δt = 20 ms, ΔC = 2 fF) show the signal of the first electrode 9.7 during a fitness test. FIG. 10 shows the signal of the banknote 2 without the adhesive strip 22 and FIG. 11 shows the signal of bank note 2 as shown with adhesive tape 22. The adhesive tape 22 leads to a recognizable increase in the measurement signal in the relevant region 26.

The result of another fitness test is shown in FIG. 12 (Δt = 20 ms, ΔC = 2 fF). The measurement signal of the first electrode 9.3 shows in the corresponding area 27 on the bank note 2 is covered with correction fluid 21, a clear drop.

Figure 13 (Δt = 20 ms, ΔC = 2 fF) shows the signal of the first electrode 9.1. This sweeps over the area of the banknote 2, which includes the staple 20. The staple 20 is attached to the bank note 2 such that the two bent ends the clip on the side of the bank note 2 facing the electrode arrangement. The two, which originate from the bent ends of the staple 20, are clear To recognize increases 28.1, 28.2 of the measurement signal.

In the signal shown in FIG. 14 (Δt = 50 ms, ΔC = 20 fF), the bank note 2 not transversely to the transport direction, but in the longitudinal direction on the detection unit 4 past. The scanning direction is therefore not the direction of the arrow 17, but that of the Arrow 29, the first electrode 9.1 to 9.8 being used for the measurement, which the area of the banknote 2 with the kinegram 18 and the security strip 19 sweeps (dashed extension of arrow 29).

The first rise 30.1 of the measurement signal stems from the kinegram 18 and the second rise 30.2 from the security strip.

The most important steps of the process according to the invention are shown in a flow chart in FIG Test procedure shown. After a banknote 2, for example, by the Entry slot in the banknote checking device 1, it is in a first Step note transport 31 is guided along the specified transport route. In one Next step feature determination 32 are, for example, with a recognition unit 4.1 Determines the optical properties of banknote 2 and immediately afterwards or evaluated later. In a calibration step 33, the electrode arrangement calibrated before the banknote 2 is subsequently checked. While the banknote 2 is guided past the recognition unit 4, a capacity pattern of the banknote 2 created. For this purpose, there will be a plurality in the relatively short time available performed by process steps that are repeated a certain number of times. In the present example, the steps are electrode selection 34, shielding 35, measurement 36 and measurement storage 37 per electrode 20 times, i.e. H. all in all Repeated 160 times. This loop with a predetermined number of passes is through the Arrow 38 indicated.

The next first electrode 9.1 to 9.8 (in a predetermined order) connected to the measuring unit. The control of the corresponding components are made by the control unit, an electronic one Circuit, which is located on the back of the board 12. Because each has the capacity is measured between a first electrode 9.1 to 9.8 and the second electrode 10, the second electrode is firmly connected to the measuring unit. This way you get finally 160 measured values of the entire banknote 2, d. H. 20 measurements for each electrode in the direction of transport.

In the case of the shield 35, all those not involved in the current measurement are first electrodes 9.1 to 9.8 switched to ground. This leads to significantly less Noise and disturbances in the measurement signals, which are caused, for example, by a signal in the Banknote checking device 1 existing engine can be caused.

If all electrodes are correctly connected, the capacitance is measured 36 between the two electrodes connected to the measuring unit. For measuring the capacity or their change, any measuring method can be used, whereby a method based on the charge transfer method is preferred.

When the measured value is stored 37, the measured value is used for later evaluation stored in a memory. This is either directly on the board 12 or for example integrated in the central control 6.

When the scanning of the banknote 2 is finished, the evaluation 39 of the collected takes place Data. The data for central control are transmitted via data lines 5.1, 5.2. where the data is evaluated after any preparation. The evaluation 39 of the data includes, for example, the determination of the type and the nominal value of the Banknote 2 by comparing the measured values with those previously stored Sample data of previously scanned banknotes. Or the measured values are used to determine whether the banknote 2 staples, adhesive tape, areas covered with correction fluid or has other features such as high wear and the like. The evaluation 39 still takes place while the banknote is on the transport path from the recognition unit is led away.

After the evaluation 39 there is finally the step consequences 40. Here 39 different measures are initiated depending on the result of the evaluation. is For example, if the banknote is recognized as genuine and in good condition, it will be in a corresponding note storage. If it has been recognized as a forgery, will they sorted out and stored, for example, in a separate memory, also further measures such as an alarm are conceivable. Also banknotes 2, which indeed Be recognized as real, but fail the fitness test, in a separate one Memory be directed. Finally, banknotes that, for example, none correspond to the intended cases, also output again via the input slot become.

In summary, it should be noted that the invention is a simple implementation and inexpensive test device that allows the detection of a variety of different Allows characteristics of a security with a single sensor. To this Wise is a simple and secure check of securities for authenticity and their condition possible.

Claims (15)

Electrode arrangement with a plurality of electrodes for checking a security, in particular a bank note, characterized in that it is two-dimensional and comprises a plurality of first electrodes and at least one second electrode, the first electrodes being at least partially surrounded by the at least one second electrode. Electrode arrangement according to claim 1, characterized in that the first electrodes are rectangular and are arranged side by side in at least one row. Electrode arrangement according to claim 1 or 2, characterized in that it has at least two and at most 256, in particular 8 or 16 first electrodes and exactly one second electrode, the first electrodes each have an area between 10 mm ² and 500 mm ² , in particular about 200 mm ² , the second electrode completely surrounds the first electrodes and a distance between the first electrodes among one another and between the first electrodes and the second electrode is greater than 0.1 mm and less than 10 mm, in particular 1 mm. Detection device for checking a security, in particular a banknote, comprising a measuring unit, a control unit and an electrode arrangement with a plurality of electrodes, characterized in that the electrode arrangement is two-dimensional, comprises a plurality of first electrodes and at least one second electrode, the first electrodes being at least partially surrounded by the at least one second electrode, is applied to a main surface of a plate-shaped substrate and the measuring unit for measuring a capacitance of two electrodes can be connected to each electrode. Detection device according to claim 4, characterized in that the substrate has a thickness between 0.1 mm and 10 mm, in particular between 1 mm and 2 mm and a dielectric constant ε _r less than 10, in particular between 3 and 5. Detection device according to claim 4 or 5, characterized in that the control unit and the measuring unit are provided on a main surface of the plate-shaped substrate opposite the electrode arrangement, the substrate is constructed in multiple layers for the production of electrical connections, and the electrodes can be switched individually to a predetermined voltage potential. Securities testing device with a transport device for transporting a security along a transport path and a detection device with an electrode arrangement having a plurality of electrodes, characterized in that the detection device comprises a measuring unit and a control unit, the electrode arrangement is two-dimensional, comprises a plurality of first electrodes and at least one second electrode, the first electrodes being at least partially surrounded by the at least one second electrode, the first electrodes are rectangular and are arranged next to one another in at least one row transversely to the transport path, the measuring unit can be connected to each electrode, the transport path leads past the detection device and the security check device is designed such that a capacity pattern of the security can be determined. Security testing device according to claim 7, characterized in that it has at least one additional sensor arrangement, in particular for determining an optical property of the security. Method for testing securities, in particular using a securities testing device according to one of claims 7 or 8, wherein a security is a transport path transported along and on a plurality of electrodes Electrode assembly is passed and while the security on the electrode assembly is guided past, with the help of a control unit and a Unit of measurement a capacity pattern of the security is determined by both transversely a plurality of capacity measurements for the transport path and also in the direction of the transport path be performed. A method according to claim 9, characterized in that the electrode arrangement is calibrated before the capacitance measurements. A method according to claim 9 or 10, characterized in that a change in capacitance between two electrodes is measured during a capacitance measurement using a measurement method based on a charge transfer method. Method according to one of claims 9 to 11, characterized in that one of the first and the second electrode are connected to the measuring unit during a capacitance measurement. A method according to claim 12, characterized in that the remaining first electrodes and the second electrode are switched to a predetermined voltage potential. Method according to one of claims 9 to 13, characterized in that the capacitance measurements are carried out at a frequency in the order of 2 kHz. Method according to one of Claims 9 to 14, characterized in that the security is guided past an additional sensor arrangement in front of the electrode arrangement and an angular position of the security in relation to the transport path and further optical properties, in particular a position of one or more security features of the security, is determined ,

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