EP2997553B1 - Device and method for examining value documents, in particular banknotes, and value document processing system - Google Patents

Description

The invention relates to a device and a method for checking value documents, in particular banknotes, as well as a value-document processing system.

In banknote processing systems, characteristics of banknotes, such as banknotes, are determined. Printed image, denomination, authenticity and condition, determined by physical properties of banknotes detected by sensors and the sensor data generated here are evaluated.

When checking the condition, the so-called fitness, of a banknote, it is checked whether it meets certain criteria in order to be able to be put back into circulation or removed from circulation. In addition to the degree of soiling and wear, the presence of undesirable foreign objects, usually in the form of adhesive strips or other stickers, on the banknote represents an important criterion.

The test for the presence of adhesive strips is usually carried out by measuring the thickness of the bill to be tested by means of mechanical or ultrasonic thickness sensors.

Out DE 10 2010 021 803 A1 It is also known to recognize adhesive strips on the basis of a dark-field transmission image of the banknote. There, it is exploited that adhesive strips that go beyond the edge of the banknote appear bright in the transmission image due to light scattering on the adhesive strip. If an adhesive strip overlaps the edge of the banknote, the value document edge observed in transmission deviates from the usually straight edge profile. The adhesive tape detection alone On the basis of the transmission image of the banknote is disadvantageous, since it may happen that distortions or deformations of the bill, which may occur, for example, the machine banknote transport and / or due to a not quite straight cutting edge, are mistaken for adhesive tape, since even with this one of straight edge course deviating Banknoterand is observed. Such a distorted or deformed banknote is then unnecessarily sorted out due to adhesive tape suspicion and possibly destroyed, although this could have been re-circulated.

It is an object of the present invention to specify a device, a method and a value-document processing system which makes possible the most reliable detection of foreign objects, in particular adhesive strips or other stickers, on the banknote.

This object is achieved by the apparatus, the method and the value-added processing system according to the independent claims.

The device according to the invention for checking documents of value, in particular banknotes, comprises: at least one sensor for detecting electromagnetic radiation transmitted by a document of value and generation of corresponding first sensor signals and for detecting electromagnetic radiation remitted by the document of value and generation of corresponding second sensor signals and an evaluation device for checking whether the value document has a foreign object, in particular an adhesive strip, taking into account first and second sensor signals which correspond to the respective electromagnetic radiation transmitted or remitted in the region of the edge of the value document.

The invention is based on the idea of using both the transmission properties and the remission properties in the region of the edge of the value document when checking whether a foreign object, in particular an adhesive strip or another sticker, is present on the value document. In this case, the presence of a foreign object is deduced on the basis of any differences between the edge profile determined from the transmission image and the edge profile of the value document determined from the remission image.

The method according to the invention for checking value documents, in particular banknotes, comprises the following steps: detecting electromagnetic radiation transmitted by a value document and generating corresponding first sensor signals, detecting electromagnetic radiation reflected from the value document and generating corresponding second sensor signals, and checking whether the value document a foreign object, in particular an adhesive strip, having regard to first and second sensor signals corresponding to the respectively transmitted in the region of the edge of the value document or remitted electromagnetic radiation, wherein on the basis of any differences between the determined from the transmission image edge profile and from the Remittance image determined edge course of the value document, on the presence of a foreign object is closed.

The value-document processing system according to the invention has at least one device for processing, in particular for conveying and / or counting and / or sorting, value documents, in particular banknotes, and is distinguished by the device according to the invention for checking value documents.

The approach according to the invention is particularly suitable for recognizing adhesive strips or other stickers located on documents of value which are affixed to the document of value for repair purposes, for example, in order to remedy defects, in particular cracks, which usually occur in the marginal area of the document of value. In particular, this makes it possible to recognize those adhesive strips which protrude beyond the cut edge of the value document or possibly even slightly beyond it.

As tests have shown, such adhesive objects are recognizable in the region of the edge of the recorded transmission image in the form of an increased brightness relative to the background, whereas the remission image in the corresponding edge region shows no changed brightness curve. This behavior can be explained by the fact that when detecting the transmission image, in particular a dark field transmission image, the light incident on the adhesive object is scattered beyond the cut edge of the value document and is detected during the transmission measurement. As an alternative or in addition to the scattering of the light, it is also possible for the incident light to be conducted from the adhesive object to the cut edge of the adhesive object, where it diffuses out, which, as a result, also results in the emission of light in the corresponding edge region of the value document. In the remission image, however, the adhesive object does not provide increased brightness, so that the actual edge of the respective banknote is observed there.

The approach according to the invention for detecting foreign objects on the document of value is particularly suitable for objects which scatter, break and / or conduct electromagnetic radiation in the visible and / or infrared and / or ultraviolet spectral range. Can be detected both Clearly appearing adhesive strips as well as for adhesive strips, which appear dull and are almost invisible on the banknote. In principle, however, this also applies to adhesive strips which are substantially opaque in the visible spectral range, for example so-called insulating tapes which can scatter electromagnetic radiation in other spectral ranges, in particular in the ultraviolet and / or infrared spectral range.

The particular advantage of the approach according to the invention of taking into account not only the transmission properties but also the remission properties of the value document along the edge is that the course of the edge in the transmission image changes from the course of the edge in the remission image in the area of one on the value document clearly differentiate the adhesive strip. By contrast, the curves in the transmission and remission image are identical in the case of distortions or deformations occurring at the edge of the value document. Such distortions or deformations of the bill may be e.g. occur during machine banknote transport and / or due to a not quite straight cutting edge. If the deviations from the rectangular shape are not too large, banknotes with such distortions or bulges are not sorted out during the condition check of the banknote. Banknotes having an adhesive strip are reliably distinguished from banknotes showing only a deformation or bulge by comparing the two margins. This prevents the latter from being incorrectly removed from circulation and, if necessary, destroyed.

The invention thus allows reliable detection of foreign objects, in particular adhesive strips or other stickers, on documents of value.

The at least one sensor is designed for spatially resolved detection of the electromagnetic radiation transmitted or remitted by the value document and for generating corresponding first or second sensor signals. In this way, during the check as to whether the document of value has an adhesive strip, the spatial progression of both the spatially resolved first sensor signal and the spatially resolved second sensor signal obtained in the region of the edge, in particular along the edge, of the value document can be taken into account, resulting in reliable differentiation of value documents and without adhesive tape allows.

The at least one sensor is designed to generate a transmission image composed of first sensor signals, in particular a dark field transmission image, and a remission image composed of second sensor signals. In a dark field transmission image, the transmission image of the value document is distinguished from a dark image background, whereby, even with low contrasts in the value document, nevertheless well-resolved, high-contrast transmission images are obtained. For this purpose, the value document is subjected to electromagnetic radiation in such a way that direct rays pass the sensor and only those which are deflected in the value document, in particular broken and / or scattered, can reach the sensor. A remission image is a spatially resolved image of the diffuse or directionally reflected electromagnetic radiation from the value document. This embodiment also makes it possible, in the examination of the value document, to take into account the spatial profile of the first sensor signal and the second sensor signal obtained in each case in the region of the edge, in particular along the edge, of the value document in order to obtain a particularly reliable To ensure distinction of value documents with and without adhesive tape.

According to a further preferred embodiment of the invention, the evaluation device is designed, in the examination of whether the document of value has a foreign object, in particular an adhesive strip, those first and second sensor signals, respectively, of the respectively transmitted in the region of the edge of the value document or remitted electromagnetic radiation match, compare with each other. If this comparison shows that the first and second sensor signals obtained in the region of the edge, in particular along the edge, of the value document have a substantially identical spatial progression, it can be concluded from this that there is no adhesive strip on the value document. On the other hand, in a section along the edge of the value document, if the spatial profile of the first sensor signals differs from the spatial profile of the second sensor signals, then the presence of an adhesive strip can be deduced therefrom. As a result, documents of value with adhesive strips can be reliably and easily distinguished from those without adhesive strips.

In particular, the positions of the edge points that the transmission image provides are compared with the positions of the corresponding edge points that the remission image provides. And for tape detection, the distance between each edge point of the transmission image and the corresponding edge point of the remission image is determined and evaluated. Normally (without adhesive strip), the two edge courses, which are observed in transmission and in remission, are approximately congruent, ie the mutually corresponding remission and transmission boundary points each have a very small distance from each other, which is below a predetermined distance comparison value. In the case of an adhesive strip, however, these edge courses are not congruent, but rather an increased distance is determined, which exceeds a predetermined distance comparison value, for example over a plurality of adjacent edge point pairs. Since the geometric distortions or bulges of the banknote are just as visible in the remission image as in the transmission image, there is also a very small distance between the remission boundary points and the transmission boundary points, which is below the distance comparison value, even in the case of geometric distortions or bulges of the banknote lies. Due to the invention, geometrical distortions or bulges of adhesive strips can therefore be distinguished. This avoids that geometrical distortions or bulges of the bill are mistaken for a false tape and the bill in question is unnecessarily sorted out.

In a particularly preferred embodiment of the invention, the evaluation device is designed to use the first sensor signals to determine one or more first edge points which correspond to points in the region of the edge of the value document, and to use the second sensor signals to determine one or more second edge points which points in the region of the edge of the value document, and to compare at least the position of one of the first edge points with the position of at least one of the second edge points. The first and second edge points, whose positions are compared with each other, are located at the same position of the value document edge, as viewed along the value document root circulating around the value document. Based on the spatial distance between the first and second edge point is checked whether in the area of the edge of the value document, a foreign object, in particular a Adhesive tape, is present. Preferably, for a plurality of pairs of first and second edge points that are adjacent edge point pairs along the edge of the value document, the position of the first edge point and the position of the second edge point corresponding thereto are respectively compared. This adhesive strips can be detected very reliable. In particular, the positions of all first and second edge points obtained along the edge of the value document are compared with each other.

Preferably, the evaluation device is designed to determine the first and / or second edge points by comparing the first and second sensor signals with at least one threshold value. Thus, for example, in the transmission image the height of the first sensor signals is compared with a first threshold value, wherein sensor signals which are greater than the first threshold value are assigned to the transmission image of the value document, whereas sensor signals which are smaller than the first threshold value, the background surrounding the value document be assigned. This can then be done by means of edge detection algorithms edge detection, in which a composite of a plurality of first boundary points edge course of the transmission image of the value document is determined. In the remission image, the height of the second sensor signals is compared with a second threshold value; Otherwise, the remarks on the transmission image apply accordingly. By means of threshold value comparison and edge detection, the first and second edge points are determined particularly accurately, which further increases the reliability in adhesive strip recognition.

It is further preferred that the evaluation device is designed to determine at least one distance value, which is a measure of the represents spatial distance of one of the first edge points of one of the second edge points, and in particular to compare the at least one distance value with at least one predetermined distance comparison value.

Moreover, it is preferred that the at least one distance comparison value corresponds to a previously determined distance value based on at least one value document on which there is no foreign object, in particular no adhesive strip. The distance comparison value can be identical for all four edges of the value document, but can also be determined separately for individual edges or each of the edges.

For example, the at least one distance value corresponds to the Euclidean distance between in each case a first and a second edge point. Alternatively, however, it is also possible to use as the distance value, for example, only the difference of that coordinate, e.g. determine the x-coordinate, the first and second edge points perpendicular to the respective edge, i. along the y-direction of the value document.

Alternatively or in addition to the determination of the distance, the size of a surface defined by the boundary points can be determined, which includes the edge profile obtained from the transmission image with the edge profile obtained from the remission image, eg by integration or by adding up the respective distance values, and checked. whether this exceeds a given area comparison value F. In the case of exceeding the area comparison value, the presence of a foreign object is affirmative, otherwise it is denied.

Additionally or alternatively, based on a statistical evaluation of the brightnesses, ie the heights of the first and second sensor signals, statements about the presence of an adhesive strip on the value document can be derived at the first and second edge points. For this, e.g. Mean values and / or variance values of the brightnesses are determined.

By one or more of the above-mentioned measures value documents can be distinguished with and without adhesive strips with very high reliability.

The respective first and second edge points, from each of which a distance value is determined, are corresponding points along the value document edge, e.g. Points with the same pixel number, if you go through the remission and the transmission edge course pixel by pixel from the same value document corner. If the transmission image and remission image are shifted relative to one another, they can be transformed into a common coordinate system in such a way that the four corner points of the transmission image coincide with the four corner points of the remission image, one of the corner points serving as a coordinate origin. A transformation of the transmission resp. Remission image can be done by translation and / or rotation of the respective coordinates. The presence of an adhesive strip on the document of value can thereby be affirmed or excluded with particular certainty.

For example, for several pairs of first and second edge points, which are preferably adjacent edge pairs along the edge of the value document, the distance value is determined in each case and it is checked whether a predetermined minimum number N of (adjacent) pairs of boundary points exceeds the distance comparison value A. In the event that the distance comparison value A is exceeded for at least a predetermined minimum number N (adjacent) pairs of edge points, the presence of a foreign object, in particular an adhesive strip, is affirmative and otherwise negated.

For example, the evaluation device is designed to determine a number n of distance values which are greater than the distance comparison value, and in particular the check as to whether the value document has a foreign object, in particular an adhesive strip, based on a comparison of the determined number n of distance values are greater than the distance comparison value, with a predetermined number N of distance values. By the predetermined number N can be set in a simple way, in how many, preferably consecutive, edge points, the edge profile of the first and second sensor signals must be different to safely conclude the presence of an adhesive strip.

For example, the minimum number N> 2, preferably N> 4, is. In addition, for the number of edge point pairs that exceed the distance comparison value, an upper limit can be set, which is selected as a function of the maximum width of the adhesive objects to be recognized, and the presence of an adhesive strip can only be affirmed if the upper limit is undershot. The distinction between value documents with and without adhesive tape becomes even more reliable.

Fig. 1

ein Beispiel eines schematischen Aufbaus eines Wertdokumentbearbeitungssystems;

Fig. 2

ein Beispiel für ein Wertdokument in Form einer Banknote;

Fig. 3

ein Beispiel für ein Transmissionsbild der in Fig. 2 gezeigten Banknote;

Fig. 4

ein Beispiel für ein Remissionsbild der in Fig. 2 gezeigten Banknote;

Fig. 5

ein Beispiel für den Verlauf des Randes des Transmissionsbildes;

Fig. 6

ein Beispiel für den Verlauf des Randes des Remissionsbildes;

Fig. 7

eine Überlagerung der in den Fig. 5 und 6 gezeigten Verläufe;

Fig. 8

ein erstes Beispiel für den Verlauf von aus ersten und zweiten Randpunkten ermittelten Abstandswerten; und

Fig. 9

ein zweites Beispiel für den Verlauf von aus ersten und zweiten Randpunkten ermittelten Abstandswerten.

Further advantages, features and applications of the present invention will become apparent from the following description taken in conjunction with the figures. Show it:

Fig. 1

an example of a schematic structure of a value-document processing system;

Fig. 2

an example of a document of value in the form of a banknote;

Fig. 3

an example of a transmission image of the in Fig. 2 banknote shown;

Fig. 4

an example of a remission picture of in Fig. 2 banknote shown;

Fig. 5

an example of the course of the edge of the transmission image;

Fig. 6

an example of the course of the edge of the remission image;

Fig. 7

a superposition of the in the Fig. 5 and 6 shown courses;

Fig. 8

a first example of the course of distance values determined from first and second boundary points; and

Fig. 9

a second example of the course of distance values determined from first and second boundary points.

Fig. 1 shows an example of a schematic structure of a value-document processing system 1 with an input tray 2, in which a stack of value documents to be processed, in particular banknotes 3, is provided, and a separator 8, of which the respective lowest Bank note of the input stack detected and transferred to a - in the selected representation only schematically reproduced - transport device 10, which conveys the bill in the transport direction T to a sensor device 20.

In the illustrated example, the sensor device 20 comprises a first, second and third sensor 21, 22 and 23, which are each preferably designed as a so-called line camera and light emitted from the banknote, in particular in the visible and / or infrared and / or ultraviolet spectral range. detected by arranged along a line sensor elements and converted into corresponding sensor signals.

In the illustrated example, the first and second sensors 21 and 22, respectively, detect from the front and back of the bill remitted, i. diffused and / or directionally reflected light, and convert this into corresponding first sensor signals. On the other hand, the third sensor 23 located in the region of the front side of the banknote detects the light transmitted by the banknote, which is emitted by a light source 24, strikes the banknote obliquely and passes through it, and converts it into corresponding second sensor signals. Due to the obliquely incident on the banknote light from the light source 24, a so-called. Dark field transmission image is detected by the third sensor, in which the banknote appears bright and their surroundings or background dark. The first and second sensors 21 and 22 are also referred to as remission cameras and the third sensor 23 is also referred to as a transmission camera.

Preferably, the line with the sensor elements of the respective sensor 21, 22 or 23 is substantially perpendicular to the transport direction T of the banknotes, so that at each read-out of the sensor line of the respective Sensors 21, 22 and 23, a sensor waveform along the sensor line is obtained, which corresponds to an intensity profile of the light, which is transmitted or remittiert in a direction perpendicular to the transport direction T extending direction of the bill.

The first and second sensor signals generated by the sensors 21 to 23 of the sensor device 20, in particular the corresponding first and second sensor signal profiles, are forwarded to a control device 50 and an evaluation device 51. The evaluation device 51 can be contained in the control device 50 or else form a separate unit from the control device 50.

In the evaluation device 51, the sensor signals are used after a possible preprocessing to check the banknote, being derived from the respective sensor signals statements about various properties of the respective banknote, such. B. the authenticity or condition of the bill, in particular the degree of soiling, wear and tear, defects and the presence of foreign objects, e.g. Adhesive strips and other stickers, but also office and staples. Contamination, wear and defects can be detected by known evaluation methods from the remission and / or transmission image, the presence of foreign objects using the evaluation of the invention.

Depending on the properties of the respective banknote determined in the evaluation device 51, the transport device 10 and the points 11 and 12 along the transport path are controlled by the control device 50 such that the banknote is fed to one of a plurality of output compartments 30 and 31 and stored there. For example, 30 banknotes are stored in a first output tray, the good Condition, in particular no foreign objects such as adhesive strips, while banknotes with bad condition, such as banknotes with adhesive strips, are stored in a second output tray 31. Counterfeit suspect banknotes are placed in another compartment (not shown).

The reference numeral 13 at the end of the transport path shown should indicate that further output compartments and / or other facilities, for example for the storage or destruction of banknotes, may be provided. If, for example, the examination of a banknote shows that it does not fulfill certain status criteria with regard to soiling, wear, defects or existing foreign objects, then this can be sent directly to a shredder for destruction.

In the illustrated example, the value-document processing system 1 further comprises an input / output device 40 for inputting data and / or control commands by an operator, for example by means of a keyboard or a touchscreen, and outputting or displaying data and / or information relating to the processing process, in particular to the respectively processed banknotes.

The value-document processing system 1 shown by way of example is particularly suited to documenting value documents for the presence of foreign objects, such as foreign objects. Adhesive strips and other stickers, to check what is explained in more detail below.

Fig. 2 shows an example of a document of value in the form of a - in the present case only very schematically illustrated - banknote 3, which is pasted with an adhesive strip 4, which protrudes slightly beyond the edge of the banknote 3 in the example shown. For reasons of clarity The adhesive strip 4 projects beyond the edge of the banknote 3 in a clearly visible manner. However, the following explanations also apply correspondingly to adhesive strips or other comparable foreign objects on banknote 3, which are flush with the edge of banknote 3.

The adhesive strip 4 may basically be any type of adhesive strip, such as e.g. transparent and / or clear and / or matt and / or transparent only in the tested spectral range adhesive tape.

The illustrated banknote 3 has in the region of its lower right corner of a deformation 5, which has also been shown enlarged in the present example for reasons of clarity and may have different causes, such. B. a production-related imperfect cutting edge of the banknote 3 or caused by the transport of the banknote 3 in a banknote processing system distortion. In the illustrated example, the deformation 5 is shown as a projection relative to the remaining course of the lower cut edge of the banknote 3. However, the following explanations also apply mutatis mutandis to all other types of deviations of the outer shape of the banknote 3 from the usual rectangular banknote form.

Fig. 3 shows an example of a transmission image 3 'of in Fig. 2 banknote 3. The transmission image 3 'shown here is preferably a so-called dark-field transmission image, which is obtained by transmitting light from the light source 24 (see FIG Fig, 1 ) obliquely, ie radiated at a substantially different angle of 90 °, with respect to the surface of the transmission camera 23 and hits the banknote 3. The light passing through the banknote 3 is detected by the transmission camera 23 and converted into corresponding first sensor signals, which together give the transmission image 3 '. The light passing past the banknote 3 as well as the transmission camera 23 causes the transmission image 3 'of the banknote 3 to appear in front of a substantially completely dark background 6 in the transmission recording shown here.

The transmission image 3 'of the banknote 3 shows a region 4' with an increased brightness compared to the dark background 6, which is due to the fact that the light striking the banknote 3 is scattered and / or refracted by the adhesive strip 4 in the direction of the transmission camera 23 and - unlike the illumination light passing past the transmission camera 23 - is detected by the transmission camera 23. In the transmission image 3 'of the banknote 3, a region 5' corresponding to the deformation 5 can also be seen.

Fig. 4 shows an example of a remission image 3 ", which in Fig. 2 banknote 3, which with one of the two remission cameras 21 and 22 (see Fig. 1 ), in that the light diffused from the banknote 3, ie directed or diffusely reflected, is detected and converted into corresponding second sensor signals, which together form the remission image 3 ".For lack of reflection or scattering of the illuminating light passing past the banknote 3 also appears the remission image 3 "of the banknote 3 in front of a substantially dark background 7.

In the remission image 3 ", one of the deformation 5 of the banknote 3 corresponding area 5" can be seen. Unlike in the transmission image 3 ', at the upper edge of a the position of the adhesive strip 4 corresponding bright area 4' can be seen (see Fig. 3 ), a corresponding area does not appear in the remission image 3 ", which can be explained by the fact that the Adhesive strip 4 causes only a small backscatter of the incident light, whereby the edge of the banknote 3 superior part of the adhesive strip 4 in the remission image 3 "can not be distinguished from the substantially uniformly dark background 7.

After recording the transmission image 3 'and the remission image 3 "of the banknote 3, the course of the edge of the respective image 3' or 3" is determined both from the transmission image 3 'and from the remission image 3 ". second signal values that contain signal values in the area of both the image 3 'and 3 "and the background 6 and 7, respectively, are compared with a threshold value. Sensor signals whose magnitude exceeds the predetermined threshold value are assigned to the transmission image 3 'or remission image 3 ", while sensor signals which fall below the predetermined threshold value are assigned to the background 6 or 7.

Subsequently, an edge detection is carried out on the transmission and remission image, in each case one of a plurality of edge points T (x, y) and R (x, y) composite course VT or VR of the edge of the transmission image 3 'or remission image 3 "of the banknote 3 is determined, which exemplifies in the Figures 5 or 6 is shown.

As already related to the FIGS. 3 and 4 1, the illustrated edge course VT of the transmission image 3 'as well as the edge profile VR of the remission image 3 "shows a deformation 5 at the edge of the bank note 3 corresponding area 5' and 5", whereas a position of the adhesive strip 4 corresponding area 4 'only occurs in the edge VT of the transmission image 3 '.

In a further step, the first and second edge points T (x, y) and R (x, y) are transformed in such a way, in particular by rotation and / or translation, that the four corners of the edge profile VT of the transmission image 3 'with the four corners The coordinates x and y of the boundary points T (x, y) and R (x, y) are then related to a common coordinate origin, which preferably - as in Fig. 7 shown - coincides with one of the four corners of the edge curves VT and VR.

Fig. 7 shows that the edge courses VT and VR in the regions 5 'and 5 "corresponding to the deformation 5 of the banknote 3 can not be distinguished from one another, whereas the first edge profile VT of the transmission image in the region 4' of the adhesive tape 4 on the banknote 3 is significantly different from the second Edge course VR of the remission image deviates.

Starting from the largely aligned edge profiles VT and VR, a distance value D is then calculated in each case for one or more pairs of edge points T (x, y) of the transmission image and edge points R (x, y) of the remission image, which is a measure of the distance between the first edge points T (x, y) from the corresponding second edge points R (x, y). For example, as the distance value D, the so-called Euclidean distance between the respective two points T (x, y) and R (x, y) is calculated as follows: $$D=\sqrt{{\left(x_T-{\mathrm{<figure-callout\; id="2"\; label="x\; R"\; filenames="imgf0001.png"\; state="\{\{state\}\}">x\; </figure-callout>}}_R\right)}^2+{\left(y_T-{\mathrm{<figure-callout\; id="2"\; label="y\; R"\; filenames="imgf0001.png"\; state="\{\{state\}\}">y\; </figure-callout>}}_R\right)}^2}$$

Where x _T and y _{T represent} the coordinates of the first edge point T (x, y) and x _R and y _{R represent} the coordinates of the second edge point R (x, y).

In principle, it is possible to calculate one or more distance values D only in certain sections of the two edge courses VT or VR. However, it is preferable to determine the distance values D for many or all of the pairs of first and second edge points T (x, y) and R (x, y) along the margins VT and VR, in order to obtain particularly high levels of adhesive tape on the banknote To recognize reliability.

Fig. 8 shows a first example of the course of distance values D determined from first and second boundary points T (x, y) and R (x, y) along the y-direction of the upper edge of the obtained transmission or remission image. In addition, the shows FIG. 8 the distance comparison value A which has been determined in advance from banknotes which have no adhesive strips or similar foreign objects. The distance comparison value A can be selected depending on the measurement accuracy of the image acquisition. For example, as a distance comparison value A, a length of 1, 2 or 3 pixel sizes of the remission or transmission image may be used. As can be seen from the figure, the distance values D in a region along the y-direction exceed the distance comparison value A, indicating a significant deviation of the edge profile VT of the transmission image compared to the edge profile VR of the remission image and thus to the adhesive strip located on the banknote 3 4 can be closed.

In comparison shows Fig. 9 a second example of the course of distance values D determined from first and second boundary points T (x, y) and R (x, y) along the y direction at the lower edge of the edge profile VT or VR. Unlike in the area of the adhesive strip 4 located on the banknote 3, those in the region of the deformation 5 of the banknote 3 exceed determined distance values D the associated distance comparison value A not, from which it can be concluded that at this point of the banknote 3 is no tape.

With the aid of the method described above or with the aid of the corresponding device, it can thus be distinguished in a simple and reliable manner whether the deviations from the edge profile of the banknote detected by image sensors are due to deformations, in particular distortions or bulges, of the banknote itself or about one located on the banknote Adhesive strips are caused. As a result, it is reliably prevented that a banknote which has only such deformations but no adhesive strips is incorrectly taken out of circulation and, if necessary, destroyed.

Claims (14)

1. An apparatus for checking value documents (3), in particular banknotes, having

   - at least one sensor (21 - 23) for capturing an electromagnetic radiation transmitted by a value document (3) and generating corresponding first sensor signals (3') that correspond to the electromagnetic radiation respectively transmitted in the region of the edge of the value document (3), and for capturing an electromagnetic radiation remitted by the value document (3) and generating corresponding second sensor signals (3") that correspond to the electromagnetic radiation respectively remitted in the region of the edge of the value document (3), wherein the at least one sensor is configured for generating a transmission image composed of first sensor signals and a remission image of the value document composed of second sensor signals, and

   - an evaluation device (51) for checking whether the value document (3) has a foreign object (4), in particular adhesive tape, taking into account the first sensor signals (3') and taking into account the second sensor signals (3"), wherein on the basis of possible differences between an edge course of the value document ascertained from the transmission image of the value document and an edge course of the value document ascertained from the remission image of the value document a conclusion is drawn as to the presence of a foreign object.
2. The apparatus according to claim 1, wherein the evaluation device (51) is configured such that, upon the check of whether the value document (3) has a foreign object (4), in particular adhesive tape, it compares with each other the first sensor signals (3') that correspond to the electromagnetic radiation respectively transmitted in the region of the edge of the value document (3), and the second sensor signals (3") that correspond to the electromagnetic radiation respectively remitted in the region of the edge of the value document (3).
3. The apparatus according to either of the preceding claims, wherein the evaluation device (51) is configured for

   - ascertaining on the basis of the first sensor signals (3') one or more first edge points (T(x, y)) that correspond to the edge of the value document (3),

   - ascertaining on the basis of the second sensor signals (3") one or more second edge points (R(x, y)) that correspond to the edge of the value document (3), and

   - comparing the position of at least one of the first edge points (T(x, y)) with the position of at least one of the second edge points (R(x, y)) in order to ascertain a spatial distance between the respective first and the second edge point and/or an area between the first and the second edge points, wherein the positions of those first and second edge points (T(x, y), R(x, y)) are compared with each other that are mutually corresponding points along the edge of the value document (3), and

   - checking on the basis of the spatial distance and/or the area whether a foreign object, in particular adhesive tape, is present in the region of the edge of the value document.
4. The apparatus according to claim 3, wherein the evaluation device (51) is configured for comparing the spatial distance with at least one pre-specified distance comparison value (A), and/or the area with at least one pre-specified area comparison value (F), and, if the distance exceeds the distance comparison value (A) and/or the area the area comparison value (F), for affirming the presence of a foreign object (4), in particular adhesive tape, and otherwise negating the presence of a foreign object (4), in particular adhesive tape.
5. The apparatus according to claim 4, wherein the at least one distance comparison value (A)/area comparison value (F) corresponds to a distance value/area value ascertained on the basis of at least one value document on which no foreign object, in particular no adhesive tape, is located.
6. The apparatus according to any of claims 3 to 5, wherein the evaluation device (51) is configured for ascertaining the position of the at least one first/second edge point (T(x, y), R(x, y)) by comparing the first/ second sensor signals (3' and 3") with at least one threshold value.
7. The apparatus according to any of claims 3 to 6, wherein the course of the value-document edge is ascertained in transmission from the first sensor signals (3') by means of edge detection and the positions of a multiplicity of first edge points are ascertained therefrom, and wherein the edge course of the value document is ascertained in remission from the second sensor signals (3') by means of edge detection and the positions of a multiplicity of second edge points therefrom.
8. The apparatus according to any of claims 3 to 7, wherein the evaluation device (51) is configured for ascertaining a distance value (D) for the spatial distance between the respective first edge point and the respective second edge point that corresponds to the respective first edge point along the edge of the value document (3), said value representing a measure of the spatial distance of the respective first edge point (T(x, y)) from the respective second edge point (R(x, y)).
9. The apparatus according to any of claims 3 to 8, wherein the evaluation device (51) is configured for

   - respectively ascertaining a distance value (D) for a plurality of pairs of a first and a second edge point, and checking whether a pre-specified minimum number (N) of pairs of edge points exceeds the distance comparison value (A), and

   - if the distance value (D) exceeds the distance comparison value (A) for at least a pre-specified minimum number (N) of pairs of edge points, affirming the presence of a foreign object (4), in particular adhesive tape, and otherwise negating the presence of a foreign object (4), in particular adhesive tape.
10. The apparatus according to any of claims 3 to 9, wherein the evaluation device (51) is configured for ascertaining a number (n) of distance values (D) that are greater than the distance comparison value (A), and for carrying out the check of whether the value document (3) has a foreign object (4), in particular adhesive tape, on the basis of a comparison of the ascertained number (n) of distance values (D) that are greater than the distance comparison value (A) with a pre-specified minimum number (N) of distance values.
11. The apparatus according to any of claims 8 to 10, wherein the at least one distance value (D) is the Euclidean distance between a first and a second edge point (T(x, y), R(x, y)) in each case.
12. The apparatus according to any of the preceding claims, wherein the at least one sensor (21 - 23) is configured for the spatially resolved capture of the electromagnetic radiation transmitted by the value document (3) and the electromagnetic radiation remitted by the value document and for generating corresponding first and second sensor signals (3' and 3").
13. A value-document processing system (1) having at least one apparatus (2, 8, 10 - 13, 30, 31, 50) for processing, in particular conveying and/or counting and/or sorting, value documents (3), in particular bank notes, and having an apparatus (21 - 23, 51) for checking value documents (3) according to any of the preceding claims.
14. A method for checking value documents (3), in particular banknotes, having the following steps of:

    - capturing an electromagnetic radiation transmitted by a value document (3) and generating corresponding first sensor signals (3') and a transmission image of the value document composed of first sensor signals,

    - capturing an electromagnetic radiation remitted by the value document (3) and generating corresponding second sensor signals (3") and a remission image of the value document composed of second sensor signals, and

    - checking whether the value document (3) has a foreign object (4), in particular adhesive tape, taking into account the first and second sensor signals (3', 3") that correspond to the electromagnetic radiation respectively transmitted or remitted in the region of the edge of the value document (3), wherein on the basis of possible differences between an edge course of the value document ascertained from the transmission image of the value document and an edge course of the value document ascertained from the remission image of the value document a conclusion is drawn as to the presence of a foreign object.

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