DEVICE AND METHOD FOR CHECKING VALUE DOCUMENTS, IN PARTICULAR BANKNOTES, AND VALUE DOCUMENT PROCESSING SYSTEM

Abstract

An apparatus and a corresponding method for checking value documents, involves at least one first sensor configured to detect electromagnetic radiation reflected and/or transmitted by a value document and to convert the radiation into corresponding first sensor signals. At least one second sensor is configured to detect sound waves reflected and/or transmitted by the value document and to convert the sound waves into corresponding second sensor signals, and an evaluation device configured to determine a first area value which characterizes a first area of the value document on the basis of the first sensor signals, to determine a second area value which characterizes a second area of the value document on the basis of the second sensor signals, and to infer a possible identification marking of the value document with a marking ink on the basis of the first and second area value.

Claims

1.-12. (canceled)

13. An apparatus for checking value documents, in particular banknotes, having at least one first sensor, which is configured to detect electromagnetic radiation reflected and/or transmitted by a value document and to convert said radiation into corresponding first sensor signals, and at least one second sensor, which is configured to detect sound waves, in particular ultrasonic waves, reflected and/or transmitted by the value document and to convert said waves into corresponding second sensor signals, wherein an evaluation device, which is configured to determine a first area value characterizing a first area of the value document on the basis of the first sensor signals, to determine a second area value characterizing a second area of the value document on the basis of the second sensor signals, and to infer a possible identification marking of the value document with a marking ink on the basis of the first and second area values.

14. The apparatus according to claim 13, wherein the evaluation device is configured to infer an identification marking of the value document with a marking ink when the difference between the second area value and the first area value exceeds a predetermined first value.

15. The apparatus according to claim 13, wherein the evaluation device is configured to infer an identification marking of the value document with a marking ink when the quotient of the second area value and the first area value exceeds a predetermined second value.

16. The apparatus according to claim 13, wherein the evaluation device is configured to infer an identification marking of the value document with a marking ink when a relative deviation of the second area value from the first area value exceeds a predetermined third value.

17. The apparatus according to claim 14, wherein the evaluation device is configured to predetermine the first, second or third value in dependence on the denomination of the value document.

18. The apparatus according to claim 13, wherein the evaluation device is configured to infer an identification marking of the value document with marking ink on the basis of first sensor signals which are obtained from the electromagnetic radiation reflected and/or transmitted in at least one edge region of the value document.

19. The apparatus according to claim 13, wherein the evaluation device is configured to infer an identification marking of the value document with marking ink on the basis of first sensor signals which are obtained from the electromagnetic radiation reflected and/or transmitted in at least one predetermined region of the value document.

20. The apparatus according to claim 19, wherein the evaluation device is configured to predetermine the at least one predetermined region in dependence on the denomination of the value document.

21. The apparatus according to claim 13 with one or several transport elements, in particular transport belts, which are configured to transport the value document relative to the second sensor, wherein the transport elements cover one or several first regions of the value document, and wherein the evaluation device is configured to determine by estimation the second area value on the basis of second sensor signals which are obtained from the sound waves reflected and/or transmitted in the one or several second regions of the value document which are not covered by the transport elements.

22. The apparatus according to claim 13, wherein the at least one first sensor is configured to detect electromagnetic radiation in the infrared range of the spectrum and to convert said radiation into corresponding first sensor signals.

23. A value document processing system with at least one apparatus for processing, in particular for conveying and/or counting and/or sorting, of value documents, in particular banknotes, and an apparatus according to claim 13.

24. A method for checking value documents, in particular banknotes, having the following steps of: detecting electromagnetic radiation reflected and/or transmitted by a value document, and converting the detected electromagnetic radiation into corresponding first sensor signals and detecting sound waves, in particular ultrasonic waves, reflected and/or transmitted by the value document, and converting the detected sound waves into corresponding second sensor signals, wherein the following steps of: determining a first area value characterizing a first area of the value document on the basis of the first sensor signals, determining a second area value characterizing a second area of the value document on the basis of the second sensor signals and determining whether the value document is possibly marked with a marking ink on the basis of the first and second area values.

Description

[0029] Further advantages, features and application possibilities of the present invention will result from the following description in connection with the figures. There are shown:

[0030] FIG. 1 an example of a structure of a value document processing system in a schematic representation;

[0031] FIG. 2 a) a first example and b) a second example of a value document to be checked in the form of a banknote;

[0032] FIG. 3 a first example of a detected image of a banknote;

[0033] FIG. 4 a second example of a detected image of a banknote; and

[0034] FIG. 5 an example of a banknote located in a sensor device.

[0035] FIG. 1 shows an example of a schematic structure of a value document processing system 1 having an input pocket 2, in which a stack of value documents to be processed, in particular banknotes 3, is supplied, and a singler 8, by which the respectively lowermost banknote of the input stack is grasped and is transferred to a transport device 10only schematically reproduced in the selected representation, which conveys the banknote in the transport direction T to a sensor device 20.

[0036] In the example shown, the sensor device 20 comprises a first sensor 21 and a further first sensor 22, which are each preferably configured as a so-called line camera or surface camera and, by means of sensor elements arranged along a line or area, in spatially resolved manner detect light emanating from the banknote, in particular in the visible and/or infrared and/or ultraviolet spectral range and convert said light into corresponding sensor signals.

[0037] In the example shown, the first sensor 21 detects the light emitted by a radiation source (not shown) and incident onto the banknote and remitted, i.e. diffusely and/or directionally reflected, by said banknote, and converts said light into corresponding first sensor signals. Accordingly, the further first sensor 22 detects the light remitted, i.e. diffusely and/or directionally reflected, by the back side of the banknote, and converts said light into corresponding further first sensor signals.

[0038] The sensor device 20 further comprises a second sensor 24, which is preferably configured as an ultrasonic sensor, and detects ultrasonic waves emanating from an ultrasound source 25, which pass through the banknote, i.e. are transmitted, and converts said ultrasonic waves into corresponding second sensor signals. The second sensor 24 and/or the ultrasound source 25 preferably have piezoelectric elements which are configured to convert incident ultrasonic waves into an alternating voltage and/or an applied alternating voltage into ultrasonic waves. Instead of a conversion into an alternating voltage, in principle any signal suitable for the qualitative and/or quantitative description of the sensor signal can be chosen, for example a mixed voltage, a digital signal, a frequency-modulated signal or an analog DC voltage.

[0039] Particularly preferably, the second sensor 24 has a plurality of sensor elements arranged in a row or area, in particular piezoelectric elements, through which the ultrasonic waves passing through the banknote can be detected in a spatially resolved manner.

[0040] Preferably, the line extends with the sensor elements of the respective sensor 21, 22 or 24 substantially perpendicularly to the transport direction T of the banknotes, so that during each read-out operation in the respective sensor 21, 22 or 24 a first or second sensor signal profile along the sensor line is obtained, which corresponds to an intensity profile of the light which is remitted or the ultrasonic waves which are transmitted by the banknote in a direction extending perpendicularly to the transport direction T.

[0041] The first and second sensor signals generated by the sensors 21, 22 and 24 of the sensor device 20, in particular the corresponding first or 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, but can also form a unit separate from the control device 50.

[0042] In the evaluation device 51, the sensor signals, optionally after a pre-processing, are employed to check the respective banknote, wherein statements about different properties of the banknote are derived from the respective sensor signals, such as, for example, denomination, authenticity, degree of soiling, wear, defects, the presence of foreign objects, such as e.g. adhesive strips, other stickers, paper clips and staples, and in particular the presence of an identification marking or coloring of the banknote with marking ink.

[0043] Depending on the properties of the respective banknote determined in the evaluation device 51, the transport apparatus 10 and the switches 11 and 12 along the transport path are controlled by the control device 50 such that the banknote is fed to one of several output pockets 30 and 31 and is stored there. For example, such banknotes are stored in a first output pocket 30 which have been recognized as not marked with a marking ink and, optionally, also fulfill further criteria, for example with regard to authenticity, soiling and fitness, whereas the banknotes classified as marked with a marking ink are stored in a second output pocket 31.

[0044] The reference number 13 at the end of the illustrated transport path is intended to indicate that further output pockets and/or other devices, for example for storing banknotes classified as inauthentic, can be provided.

[0045] Alternatively, it can be provided that a banknote marked with a marking ink, in particular in the form of a blackening of larger and/or specific areal regions of the banknote, is transferred directly into a shredder (not shown) for destruction or into a manual processing pocket for banknotes suspected of forgery, instead of being transferred into the second output pocket 31.

[0046] In the example represented, 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 touch screen, and outputting or displaying data and/or information relating to the processing process, in particular to the respectively processed banknotes.

[0047] The value document processing system 1 shown by way of example is particularly suitable for checking value documents for the presence of an identification marking by marking ink, which is explained in more detail below.

[0048] FIG. 2a) shows a first example of a value document in the form of a banknote 3represented only strongly schematically in the present case, which has been colored with marking ink, in particular blackened, in a region 4 at the upper edge of the banknote 3. In the present example, the blackened region 4 extends over the entire width of the banknote 3. However, the following explanations also apply correspondingly to markings of any size and position on the banknote 3.

[0049] When electromagnetic radiation, in particular infrared radiation and/or visible light, is incident on the banknote 3, said radiation is remitted in dependence on the optical properties, such as absorption and scattering, of the banknote, and detected by the first sensors 21 or 22 (see FIG. 1) and converted into corresponding first sensor signals. Here, the electromagnetic radiation incident on the region 4 of the banknote 3 colored with marking ink is not remitted or only slightly remitted, since the marking ink strongly absorbs the incident radiation. A first area value computed on the basis of the corresponding first sensor signals, such as, for example, the size and/or shape of the detected image of the banknote 3, in the present example therefore characterizes a first area which corresponds to the actual area of the banknote 3 minus the region 4 colored with marking ink.

[0050] Ultrasonic waves emitted by the ultrasound source 25 (see FIG. 1), on the other hand, are transmitted in the same manner by the entire area of the banknote 3, i.e. in particular also by the region 4 colored with marking ink, so that a second area value determined on the basis of the second sensor signals, such as, for example, the size and/or shape of the detected image of the banknote 3, characterizes the actual area of the banknote 3.

[0051] In the present case, the second area value determined on the basis of the ultrasonic sensor signals is thus higher than the first area value determined on the basis of the optical sensor signals.

[0052] When a difference between the second and the first area value is determined and/or the difference exceeds a certain predetermined threshold value, thus, the presence of a possible identification marking of the banknote 3 with marking ink can be inferred. A difference between the second and the first area value can be determined, for example, by comparing the determined area values and/or by forming a difference or a quotient of the second and the first area value. Preferably, as a measure for the difference, there is determined the difference between the second and the first area value relative to the second area value, i.e. a relative deviation of the two area values from one another.

[0053] For example, it can be provided that a banknote 3 is classified as a banknote 3 possibly marked with marking ink, if the relative deviation of the area values is greater than a predetermined threshold value. Preferred threshold values are between about 2 and 8%. Particularly preferably, the threshold value is about 4%.

[0054] In the second example shown in FIG. 2b), the banknote 3 is bent in such a way that a region 5 (dashed) of the banknote 3 is not visible. In this example, a first area value determined on the basis of the first sensor signals characterizes an area which is exactly as large as the area which is characterized by the second area value obtained from the second sensor signals. In this case, the first and second area values are substantially identical, so that the banknote 3 is not incorrectly classified as a banknote colored with a marking ink, such as the banknote 3 in the first example of FIG. 2a).

[0055] Preferably, here a classification of the banknote 3 as a banknote marked with marking ink is effected only preliminarily, wherein the banknote 3 is initially classified on the basis of the first and second area values only as possibly marked with marking ink and is subjected to one or several further checks, in which the banknote 3 is checked in a different manner for the presence of marking ink and, depending on the result of the check, is then finally classified accordingly. This is preferably effected by checking edge regions of the banknote 3 and/or by means of so-called template matching, in which certain regions of the banknote 3 are subjected to a check. This is explained in more detail below with reference to FIGS. 3 and 4.

[0056] FIG. 3 shows a first example of an image of a banknote 3 detected with one of the first sensors 21, 22 (see FIG. 1), which banknote is marked with a marking ink in the region 4. Several edge regions 6 are drawn in in the reproduced image of the banknote 3, which are checked for the presence of marking ink.

[0057] The narrow edge regions 6 are preferably arranged such that their longitudinal sides lie parallel to the edges of the banknote 3. The edge regions 6 are typically located between 1 to 4 mm from the edges and have a width of between about 1 and 3 mm. The edge regions 6 are further preferably arranged such that certain regions of the banknote 3 are left out, such as, for example, security features 7 in the form of holographic elements.

[0058] The evaluation device 51 (see FIG. 1) is preferably configured to count a number of first sensor signals in the edge regions 6, said sensor signals lying in a specific signal strength range, and to infer therefrom a possible identification marking of the banknote 3 with marking ink. For example, all image points (pixels) in the respective edge region 6 of the camera image are counted the brightness of which lies between a first brightness value, for example 50, and a second brightness value, for example 800. Thereby image points from the dark background of the banknote, which typically have brightness values of less than 50, and image points from the unblackened banknote, which typically have brightness values of more than 800, are masked out, and only such image points are counted which have a typical brightness for a blackening of the banknote 3.

[0059] The above-described check of the edge regions 6 of the banknote 3 is preferably effected when a statement with reference to an identification marking of the banknote 3 with marking ink is impossible or not possible with the required reliability on the basis of the first and second area values alone.

[0060] When the presence of an ink marking cannot be inferred or cannot be reliably inferred on the basis of this check either, for example in the case of banknotes where an attempt was made to wash off the marking ink, a further check of the banknote 3 can be provided. Here, images recorded of the banknote 3 are preferably subjected to a so-called template matching, which is explained in more detail below.

[0061] FIG. 4 shows a second example of an image of a banknote 3 detected with one of the first sensors 21, 22 (see FIG. 1). In this example a hatched region 9 indicates the region in which the electromagnetic radiation remitted by the banknote 3 and detected by the first sensors 21, 22 is evaluated for recognizing an ink marking. Regions of the banknote 3 are left out (represented transparent) from the hatched region 9 which are not suitable for recognizing an ink marking, such as, for example, regions with a dark IR print and/or with a hologram foil (so-called patch, LEAD).

[0062] The hatched region 9, which is also referred to as a mask or template, is preferably configured to be denomination-specific, i.e. selected in dependence on the determined nominal value of the banknote 3, and/or to be position-specific, i.e. selected in accordance with the orientation of the banknote 3.

[0063] In the present example, preferably all image points (pixels) in the region 9 of the camera image are counted the brightness of which exceeds a predetermined brightness value, such as 1500. In this way, it is ensured that normal soiling and watermarks are not incorrectly identified as an identification marking with marking ink. The number of pixels determined here is compared with a predetermined number, which depends on the size of the area of the region 9. When the determined number falls below the predetermined number, thus, the presence of marking ink in the examined region 9 can be inferred.

[0064] Preferably, a percentage match of the determined number to the predetermined number is determined and, on the basis of the result, an identification marking of the banknote 3 with marking ink is inferred.

[0065] In order to save computing time, the evaluation device 51 is preferably configured to evaluate only a part of the first sensor signals or image points in the hatched region 9. Preferably, only every third image point is checked with regard to its brightness value with reference to the predetermined threshold value and counted accordingly.

[0066] FIG. 5 shows an example of a banknote 3 located in the sensor device 20 (see FIG. 1) which is partially covered by transport elements 10, for example transport belts, of the transport device 10. This can be the case, for example, when the value document processing system is constructed as a so-called belt machine.

[0067] When the transport elements 10 are located, for example, between the second sensor 24 on the one hand and the banknote 3 or the ultrasound source 25 on the other hand, the image detected by the second sensor 24 does not contain any image information about the banknote 3 in the regions of the transport elements 10.

[0068] In this case, the size and/or shape of the missing image regions are preferably determined by estimation on the basis of the image information from the uncovered regions of the banknote 3. This is achieved, for example, in that second sensor signals or image points from image regions 15 located above and/or below a transport element 10, which were preferably detected with a sensor line, are multiplied and then replace the missing image regions. The number of multiplication here is dependent on the width of the transport elements 10 or regions covered thereby. When the width of the covered regions corresponds, for example, to a width of two sensor lines, the image region 15 lying in each case below a transport element 10 is doubled and inserted into the position of the respective transport element 10 in the corrected image. The second area value can be reliably estimated on the basis of an image corrected in this manner.

[0069] Alternatively, however, it can also be preferred to arrange the at least one ultrasonic sensor in a place where the banknotes are not covered by transport elements.