Apparatus and method for checking value documents, in particular bank notes, and value-document processing system

Abstract

An apparatus and method for checking value documents, in particular bank notes, and a value-document processing system having at least one sensor for capturing an electromagnetic radiation. Transmitted by a value document and generating corresponding first sensor signals and for capturing an electromagnetic radiation remitted by the value document and generating corresponding second sensor signals, and an evaluation device for checking whether the value document has a foreign object. In particular adhesive tape, taking into account the first and second sensor signals which correspond to the electromagnetic radiation respectively transmitted or remitted in the region of the edge of the value document. The apparatus and method prevent a deformation in the region of the edge of a value document from being identified as a foreign object.

Claims

1. An apparatus for checking value documents comprising: at least one sensor for capturing an electromagnetic radiation transmitted by a value document and generating corresponding first sensor signals which correspond to the electromagnetic radiation respectively transmitted in the region of the edge of the value document, and for capturing an electromagnetic radiation remitted by the value document and generating corresponding second sensor signals which correspond to the electromagnetic radiation respectively remitted in the region of the edge of the value document, and an evaluation device for checking whether the value document has a foreign object taking into account the first sensor signals and taking into account the second sensor signals; wherein the at least one sensor is configured for generating a transmission image, composed of first sensor signals, and a remission image composed of second sensor signals, and the evaluation device is configured for ascertaining on the basis of the first sensor signals one or more first edge points which correspond to the edge of the value document: ascertaining on the basis of the second sensor signals one or more second edge points which correspond to the edge of the value document; and checking whether the value document has a foreign object on a basis of any differences between an edge course of the value document ascertained from the transmission image and an edge course of the value document ascertained from the remission image.

2. The apparatus according to claim 1, wherein the evaluation device is configured such that, upon the check of whether the value document has a foreign object, it compares with each other the first sensor signals which correspond to the electromagnetic radiation respectively transmitted in the region of the edge of the value document, and the second sensor signals which correspond to the electromagnetic radiation respectively remitted in the region of the edge of the value document.

3. The apparatus according to claim 1, wherein the evaluation device is configured for comparing the position of at least one of the first edge points with the position of at least one of the second edge points 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, with the positions of those first and second edge points being compared with each other that are mutually corresponding points along the edge of the value document; and checking on the basis of the spatial distance and/or the area whether a foreign object, is present in the region of the edge of the value document.

4. The apparatus according to claim 3, wherein the evaluation device is configured for comparing the spatial distance with at least one pre-specified distance comparison value, and/or the area with at least one pre-specified area comparison value, and, if the distance exceeds the distance comparison value and/or the area the area comparison value, for affirming the presence of a foreign and otherwise negating the presence of a foreign object.

5. The apparatus according to claim 4, wherein the at least one distance comparison value/area comparison value corresponds to a distance value/area value ascertained on the basis of at least one value document on which no foreign object is located.

6. The apparatus according to claim 3, wherein the evaluation device is configured for ascertaining the position of the at least one first/second edge point by comparing the first/second sensor signals with at least one threshold value.

7. The apparatus according to claim 3, wherein the course of the value-document edge is ascertained in transmission from the first sensor signals 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 by means of edge detection and the positions of a multiplicity of second edge points therefrom.

8. The apparatus according to claim 3, wherein the evaluation device is configured for ascertaining a distance value for the spatial distance between the respective first edge point and the respective second edge point which corresponds to the respective first edge point along the edge of the value document, said value representing a measure of the spatial distance of the respective first edge point from the respective second edge point.

9. The apparatus according to claim 3, wherein the evaluation device is configured for: respectively ascertaining a distance value for a plurality of pairs of a first and a second edge point, and checking whether a pre-specified minimum number of pairs of edge points exceeds the distance comparison value; and if the distance value exceeds the distance comparison value for at least a pre- specified minimum number of pairs of edge points, affirming the presence of a foreign object and otherwise negating the presence of a foreign object.

10. The apparatus according to claim 3, wherein the evaluation device is configured for ascertaining a number of distance values that are greater than the distance comparison value, and for carrying out the check of whether the value document has a foreign object on the basis of a comparison of the ascertained number of distance values that are greater than the distance comparison value with a pre-specified minimum number of distance values.

11. The apparatus according to claim 8, wherein the at least one distance value is the Euclidean distance between a first and a second edge point in each case.

12. The apparatus according to claim 1, wherein the at least one sensor is configured for spatially resolved capture of the electromagnetic radiation transmitted by the value document and the electromagnetic radiation remitted by the value document and for generating corresponding first and second sensor signals.

13. A value-document processing system having at least one apparatus for processing, value documents, and having an apparatus for checking value documents according to claim 1.

14. A method for checking value documents, having the following steps: capturing an electromagnetic radiation transmitted by a value document and generating corresponding first sensor signals; capturing an electromagnetic radiation remitted by the value document and generating corresponding second sensor signals; and checking whether the value document has a foreign object, taking into account the first and second sensor signals which correspond to the electromagnetic radiation respectively transmitted or remitted in the region of the edge of the value document; wherein at least one sensor is configured for generating a transmission image, composed of the first sensor signals, and a remission image composed of the second sensor signals, and an evaluation device is configured for ascertaining on the basis of the first sensor signals one or more first edge points which correspond to the edge of the value document; ascertaining on the basis of the second sensor signals one or more second edge points which correspond to the edge of the value document; and checking whether the value document has a foreign object on a basis of any differences between an edge course of the value document ascertained from the transmission image and an edge course of the value document ascertained from the remission image.

15. An assembly for checking value documents comprising: at least one sensor for capturing an electromagnetic radiation transmitted by a value document and generating corresponding first sensor signals which correspond to the electromagnetic radiation respectively transmitted in the region of the edge of the value document, and for capturing an electromagnetic radiation remitted by the value document and generating corresponding second sensor signals which correspond to the electromagnetic radiation respectively remitted in the region of the edge of the value document, and an evaluation device for checking whether the value document has a foreign object taking into account the first sensor signals and taking into account the second sensor signals; wherein the at least one sensor is configured for generating a transmission image, composed of first sensor signals, and a remission image composed of second sensor signals, and the evaluation device is configured for ascertaining on the basis of the first sensor signals one or more first edge points which correspond to the edge of the value document; ascertaining on the basis of the second sensor signals one or more second edge points which correspond to the edge of the value document; and checking whether the value document has a foreign object on a basis of any differences between an edge course of the value document ascertained from the transmission image and an edge course of the value document ascertained from the remission image.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

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

(2) FIG. 1 an example of a schematic construction of a value-document processing system;

(3) FIG. 2 an example of a value document in the form of a bank note;

(4) FIG. 3 an example of a transmission image of the bank note shown in FIG. 2;

(5) FIG. 4 an example of a remission image of the bank note shown in FIG. 2;

(6) FIG. 5 an example of the course of the edge of the transmission image;

(7) FIG. 6 an example of the course of the edge of the remission image;

(8) FIG. 7 a superimposition of the courses shown in FIGS. 5 and 6;

(9) FIG. 8 a first example of the course of distance values ascertained from first and second edge points; and

(10) FIG. 9 a second example of the course of distance values ascertained from first and second edge points.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

(11) FIG. 1 shows an example of a schematic construction of a value-document processing system 1 having an input pocket 2 in which a stack of value documents, in particular bank notes 3, to be processed is supplied, and a singler 8 from which the respectively lowermost bank note of the inputted stack is grasped and delivered to a transport device 10—rendered only schematically in the chosen representation—which conveys the bank note to a sensor device 20 in transport direction T.

(12) The sensor device 20 comprises in the represented example a first, second and third sensor 21, 22, 23 which is respectively preferably configured as a so-called line-scan camera and captures light emanating from the bank note by means of sensor elements arranged along a line, in particular in the visible and/or infrared and/or ultraviolet spectral region, and converts it into corresponding sensor signals.

(13) In the represented example, the first and second sensors 21, 22 capture light remitted, i.e. diffusely and/or directionally reflected, by the front side or back side of the bank note and convert it into corresponding first sensor signals. The third sensor 23 located in the region of the front side of the bank note, however, captures the light transmitted through the bank note, said light being emitted by a light source 24, obliquely impinging on the bank note and passing through it, and converts it into corresponding second sensor signals. Due to the light from the light source 24 impinging on the bank note obliquely, the third sensor captures a so-called dark-field transmission image, in which the bank note appears light and its surroundings or background dark. The first and second sensors 21, 22 are also designated remission cameras, and the third sensor 23 is also designated a transmission camera.

(14) Preferably, the line with the sensor elements of the respective sensor 21, 22, 23 extends substantially perpendicularly to the transport direction T of the bank notes, so that there is obtained upon each readout operation of the sensor line of the respective sensor 21, 22, 23 a sensor signal course, along the sensor line, which corresponds to an intensity course of the light that is transmitted or remitted by the bank note in a direction extending perpendicularly to the transport direction T.

(15) 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 courses, are relayed to a control device 50 as well as an evaluation device 51. The evaluation device 51 can be contained in the control device 50 or else form a unit separate from the control device 50.

(16) In the evaluation device 51 the sensor signals, possibly after preprocessing, are drawn on for checking the bank note, with statements being derived from the respective sensor signals about different properties of the respective bank note, such as authenticity or condition of the bank note, in particular degree of soiling, wear, defects and the presence of foreign objects, such as adhesive tape and other stickers, but also paper clips and staples. Soiling, wear and defects can be recognized from the remission image and/or transmission image using known evaluation methods, and the presence of foreign objects using the evaluation according to the invention.

(17) Depending on the properties of the respective bank note that are ascertained in the evaluation device 51, the transport device 10 as well as the gates 11 and 12 along the transport line are controlled by the control device 50 such that the bank note is fed to one of a plurality of output pockets 30 and 31 and deposited there. For example, bank notes in good condition, in particular having no foreign objects such as adhesive tape, are deposited in a first output pocket 30, while bank notes in poor condition, e.g. bank notes with adhesive tape, are deposited in a second output pocket 31. Suspect bank notes are deposited in a further pocket (not shown).

(18) The reference number 13 at the end of the represented transport line in intended to indicate that further output pockets and/or other devices can be provided, for example for storing or destroying bank notes. If for example the check of a bank note shows that it does not meet certain condition criteria with regard to soiling, wear, defects or the presence of foreign objects, it can be fed directly to a shredder for destruction.

(19) The value-document processing system 1 further comprises, in the represented example, an input/output device 40 for inputting of data and/or control commands by an operating person, for example by means of a keyboard or a touchscreen, and outputting or display of data and/or information about the processing operation, in particular about the respectively processed bank notes.

(20) The value-document processing system 1 shown by way of example is especially suitable for checking value documents for the presence of foreign objects, such as adhesive tape and other stickers, which will be explained more closely hereinafter.

(21) FIG. 2 shows an example of a value document in the form of a bank note 3—represented only very schematically in the present case—bearing adhesive tape 4 which projects slightly beyond the edge of the bank note 3 in the represented example. For illustrative reasons, the adhesive tape 4 protrudes beyond the edge of the bank note 3 in a clearly visible manner. However, the following comments also apply accordingly to adhesive tape or other comparable foreign objects on the bank note 3 that are flush with the edge of the bank note 3.

(22) The adhesive tape 4 can in principle be any kind of adhesive tape, such as adhesive tape that is transparent and/or clear and/or matt and/or light-transmissive only in the checked spectral region.

(23) The represented bank note 3 has a deformation 5 in the region of its lower right corner, which has been represented in enlarged form in the present example again for illustrative reasons, and can have different causes, such as a cut edge of the bank note 3 that is imperfect for manufacturing reasons or a distortion caused by the transport of the bank note 3 in a bank-note processing system. In the represented example, the deformation 5 is represented as a projection relative to the rest of the course of the lower cut edge of the bank note 3. However, the following comments also apply accordingly to all other kinds of deviations of the outer shape of the bank note 3 from the conventional rectangular bank-note shape.

(24) FIG. 3 shows an example of a transmission image 3′ of the bank note 3 shown in FIG. 2. The transmission image 3′ represented here is preferably a so-called dark-field transmission image, which is obtained by light being emitted from the light source 24 (see FIG. 1), and impinging on the bank note 3, obliquely, i.e. at an angle clearly different from 90°, with regard to the area of the transmission camera 23. The light passing through the bank note 3 is captured by the transmission camera 23 and converted into corresponding first sensor signals which compositely yield the transmission image 3′. The light passing by the bank note 3 and passing by the transmission camera 23 leads to the transmission image 3′ of the bank note 3 appearing against a substantially completely dark background 6 in the transmission recording shown here.

(25) The transmission image 3′ of the bank note 3 shows a region 4′ having an elevated lightness relative to the dark background 6, which is due to the fact that the light impinging on the bank note 3 is scattered and/or refracted in the direction of the transmission camera 23 by the adhesive tape 4 and—unlike the illumination light passing by the transmission camera 23—is captured by the transmission camera 23. In the transmission image 3′ of the bank note 3 there is further to be recognized a region 5′ corresponding to the deformation 5.

(26) FIG. 4 shows an example of a remission image 3″ of the bank note 3 shown in FIG. 2, which was recorded with one of the two remission cameras 21, 22 (see FIG. 1) by capturing the light remitted, i.e. directionally or diffusely reflected, by the bank note 3 and converting it into corresponding second sensor signals which compositely form the remission image 3″. Due to the lack of reflection or scattering of the illumination light passing by the bank note 3, the remission image 3″ of the bank note 3 also appears against a substantially dark background 7.

(27) In the remission image 3″ there is likewise to be recognized a region 5″ corresponding to the deformation 5 of the bank note 3. However, unlike in the transmission image 3′, at whose upper edge a light region 4′ corresponding to the position of the adhesive tape 4 is to be recognized (see FIG. 3), no corresponding region occurs in the remission image 3″. This can be explained by the fact that the adhesive tape 4 causes only little backscatter of the impinging light, so that the part of the adhesive tape 4 protruding beyond the edge of the bank note 3 cannot be distinguished from the substantially uniformly dark background 7 in the remission image 3″.

(28) After the recording of the transmission image 3′ and of the remission image 3″ of the bank note 3, the course of the edge of the respective image 3′, 3″ is ascertained both from the transmission image 3′ and from the remission image 3″, e.g. by comparing the first or second signal values containing signal values in the region of both the image 3′, 3″ and the background 6, 7 with a threshold value in each case. In so doing, sensor signals whose level exceeds the pre-specified threshold value are associated with the transmission image 3′ or remission image 3″, while sensor signals undershooting the pre-specified threshold value are associated with the background 6, 7.

(29) Subsequently, an edge detection is carried out on the transmission recording and remission recording, by which a course VT, VR, composed of a multiplicity of edge points T(x, y), R(x, y), of the edge of the transmission image 3′ or remission image 3″ of the bank note 3 is respectively ascertained, said course being represented by way of example in FIGS. 5, 6.

(30) As already explained in connection with FIGS. 3 and 4, the represented edge course VT of the transmission image 3′ and the edge course VR of the remission image 3″ show a region 5′, 5″ corresponding to the deformation 5 at the edge of the bank note 3, whereas a region 4′ corresponding to the position of the adhesive tape 4 only occurs in the edge course VT of the transmission image 3′.

(31) In a further step, the first and second edge points T(x, y), R(x, y) are transformed, in particular by rotation and/or translation, such that the four corners of the edge course VT of the transmission image 3′ coincide with the four corners of the edge course VR of the remission image 3″. The coordinates x and y of the edge points T(x, y) and R(x, y) then relate to a common coordinate origin which preferably—as shown in FIG. 7—coincides with one of the four corners of the edge courses VT and VR.

(32) FIG. 7 shows that the edge courses VT and VR are mutually indistinguishable in the regions 5′ and 5″ corresponding to the deformation 5 of the bank note 3, whereas the first edge course VT of the transmission image deviates significantly from the second edge course VR of the remission image in the region 4′ of the adhesive tape 4 on the bank note 3.

(33) Starting out from the edge courses VT and VR brought almost entirely into coincidence, a distance value D is then respectively computed 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, said value representing a measure of the distance between the first edge points T(x, y) from the corresponding second edge points R(x, y). For example, there is computed as a distance value D the so-called Euclidean distance between the respective two points T(x, y) and R(x, y) as follows:

(34) where x.sub.T and y.sub.T represent the coordinates of the first edge point T(x, y), and x.sub.R and y.sub.R the coordinates of the second edge point R(x, y).

(35) In principle it is possible to compute one or more distance values D only in certain portions of the two edge courses VT, VR. However, it is preferred to determine the distance values D for many or all pairs of first and second edge points T(x, y), R(x, y) along the edge courses VT and VR in order to be able to recognize any adhesive tape on the bank note with especially high reliability.

(36) FIG. 8 shows a first example of the course of distance values D ascertained from first and second edge points T(x, y) and R(x, y), along the y direction of the upper edge of the obtained transmission or remission image. Additionally, FIG. 8 shows the distance comparison value A which was ascertained in advance on the basis of bank notes having no adhesive tape or similar foreign objects. The distance comparison value A can be chosen in dependence on the measuring accuracy of the image recording. For example, there can be employed as a distance comparison value A a length of 1, 2 or 3 pixel sizes of the remission or transmission image. As indicated by the figure, the distance values D exceed the distance comparison value A in a region along the y direction, from which one can infer a significant deviation of the edge course VT of the transmission image in comparison to the edge course VR of the remission image, and thus the adhesive tape 4 located on the bank note 3.

(37) In comparison, FIG. 9 shows a second example of the course of distance values D ascertained from first and second edge points T(x, y) and R(x, y), along the y direction on the lower edge of the edge course VT, VR. Unlike in the region of the adhesive tape 4 located on the bank note 3, the distance values D ascertained in the region of the deformation 5 of the bank note 3 do not exceed the appurtenant distance comparison value A, from which one can infer that no adhesive tape is located at this place on the bank note 3.

(38) Using the hereinabove described method, or using the corresponding apparatus, one can thus distinguish in a simple and reliable manner whether the deviations from the edge course of the bank note that are captured by means of image sensors are caused by deformations, in particular distortions or bulges, of the bank note itself or by any adhesive tape located on the bank note. As a result, this reliably prevents a bank note that has merely such deformations but no adhesive tape from being falsely taken out of circulation and possibly fed to a destruction process.