EP1668605B1

EP1668605B1 - Gate logic for sheet handling

Info

Publication number: EP1668605B1
Application number: EP04775478A
Authority: EP
Inventors: Maxim MINERSKJÖLD
Original assignee: Axlon International AB
Current assignee: Axlon International AB
Priority date: 2003-09-26
Filing date: 2004-09-24
Publication date: 2007-08-22
Anticipated expiration: 2024-09-24
Also published as: DE602004008491D1; EP1668605A1; ATE371237T1; SE0302558D0; SE0302558L; SE525650C2; WO2005031661A1

Abstract

The invention specifies a banknote reader and a method for the same for at least one of denomination determination, authenticity control and image processing of a value document. The banknote reader comprises a reading head (10) with electronic component (12) for the reading of a value document (40) and a means (18) for processing the data that has been read. The reading head is connected to a gate logic unit (32), which constitutes the said means (18), and which is programmed with an algorithm for processing the data that has been read, whereby the denomination and the authenticity of a value document (40) is determined with respect to predetermined conditions for the output signals of the gate logic unit (32).

Description

Technical Area

The present invention relates to a banknote reader that reads banknotes for at least one of determination of denomination, control of authenticity and image processing of a value document such as, for example, a banknote. It comprises a reading head with electronic components for reading a value document, and a means for processing the data that has been read.

The Prior Art

The reading of banknotes can be classified into two categories. The first category is the determination of value and denomination, while the second category is the control of authenticity. Either one category or both categories may be used, depending of the area of application and the requirements of the customer.
A common method for determining the denomination of a banknote comprises measuring its length and breadth. Swedish banknotes have different formats for each individual denomination, as do other European banknotes. There are also currencies, such as the US dollar, in which all banknotes have the same physical format. In those cases in which the banknotes of particular currencies have different formats, measurements of the length and breadth provide a unique signature for the different denominations.
A collection of measurement methods for determining the denomination of banknotes may comprise:

LENGTH in combination with BREADTH
BREADTH
IMAGE (reads the denomination for the actual currency)
AREA (measures the area of the banknote).

The first two measurement methods listed above are implemented with an IR (infrared) detector in the form of a reading fork in combination with a rotation sensor connected to the transport band in a banknote feed. A line consisting of IR detectors placed over the transport band measures the breadth.
The latter two measurement methods, on the other hand, require an advanced detector and electronic components. A banknote is read by a linear element (it is "scanned") for image processing and recognition, and according to the prior art, the data is post-processed in a microprocessor, CPU (Central Processing Unit), DSP (Digital Signal processor) or similar.
A banknote reader with image processing can carry out, for example, the following measurements:

DENOMINATION and CURRENCY (it can handle the currencies of different countries in the same machine)
BAR-CODE, DISCOUNT LABELS, DEPOSIT RECEIPTS, and similar
SERIAL NUMBERS (identification of individual banknotes for deposit machines and dispensing machines)
CURRENCY PROTECTION DYE (detection of dyed banknotes, dye staining).

The image processing for determination of denomination is relatively straightforward. Recognition of images requires specific measurement methods. Methods for this process are implemented according to the prior art in program code or using DSP-instructions. The method using DSP-instructions is the simpler method to implement since it is possible to separate the hardware and the software in a traditional manner, but the DSP-method has disadvantages in that it is expensive, requires many electronic components and thus a large area with suitable cooling and loss of, among other factors, performance due to the construction and the execution of the software.
Two or more types of detector are required in order to achieve a credible and high-quality control of authenticity. There is no method known based on a single detector that can detect false banknotes. There are indications that one euro banknote has security details that can be read with the aid of laser methods, and that cannot be reproduced. Laser methods, however, are not general, and they cannot be used for all currencies.
An authenticity control must be able to identify not only counterfeit banknotes but also invalid banknotes, i.e. authentic banknotes that have, for example, been covered by currency protection dye. In the case of counterfeit banknotes, a colour spectrum analysis of banknotes is no longer definitive, if the quality of the printing is high. Furthermore, variations in printing and in colour arise between different years and different printing presses. The euro banknote is printed in several countries and variations exist that an authenticity control must be able to handle. For this reason, a method based on a colour spectrum becomes a continuous process of adapting the method to new banknotes.
It has become apparent that it is possible to identify counterfeit banknotes by, among other methods, the following:

IR profiles with absorbing and reflecting infrared dye.
SECURITY THREAD, using magnetic detection.

The infrared dye is difficult to copy and thus achieves a good protection against counterfeit banknotes. There are several different methods used to code banknotes using infrared dye. In simple cases, the banknote is printed with various broad and narrow bands, somewhat similar to a bar-code. In other cases, certain selected areas are dyed with the infrared dye. There may be limited geometric areas or details on the banknote. A banknote reader that reads the complete banknote is required in this case.
It is difficult to manufacture and to counterfeit the security thread. It is present as a simple homogenous metallic strip, coded with holes in the strip or coated with metallic points. The presence of a security thread can be detected with the aid of a recording head similar to the head that is present in, for example, music cassette players. When decoding a security thread, several recording heads are required or one broader recording head is required, or a magnetic sensor element that is located across the transport band in the banknote feeder.
An integrated banknote evaluator is described in the document US 2003/0178282 with a number of digital cameras for image recording and evaluation of the images in an image evaluation unit, using comparison. The banknote evaluator is bulky, and it does not contain gate logic.
The patent document US-A-5,806,649 specifies a banknote evaluator with a bulky outer. The evaluator detects the edges of banknotes and evaluates the banknote using reflectance against a photosensor. It does not exhibit scanning, nor does it exhibit gate logic.

Summary of the Invention

The invention according to the present description concerns a banknote reader for at least one of determination of denomination, authenticity control, and image processing of a banknote. The invention in this way solves the problems described above, in particular problems related to the use of the method of DSP instructions and other software-based data processing methods according to the prior art. These have disadvantages in that they are expensive, require many electronic components and thus a large area with suitable cooling, operating systems and losses in, among other factors, performance due to the design and execution of the software.
The concept "banknote reader" according to the present invention is broader than solely comprising a banknote in the form of money, it is also to comprise an arrangement for reading value coupons, bar-codes, deposit receipts and other documents having a value. The banknote reader processes the input signal and specifies as an output signal what the type of value of the document is. In the same manner, the concept of "banknote" comprises also other value documents, such as value coupons, bar-codes and similar documents, when it is used according to the present invention.
The present invention specifies a hardware solution in the form of a gate logic unit in order to solve the said problems and to achieve the intended goals. The invention thus specifies a banknote reader for at least one of denomination determination, authenticity control, and image processing of a value document. It comprises a reading head with electronic components for reading a value document, and means for processing the data that is read. The reading head is connected to the gate logic unit, which constitutes the said means, and which is programmed with a measurement method/algorithm for treating the data read, whereby the denomination of a value document and its authenticity are determined with respect to predetermined conditions of the output signals of the gate logic unit.
In one embodiment of the invention, the gate logic unit is constituted by an FPGA (Field Programmable Gate Array) or similar. The gate logic unit is arranged in one embodiment on a circuit board.
According to a second embodiment, the gate logic unit is connected using circuit boards to electronic circuit boards/electronic components of the reading head through board-to-board contacts. The circuit board that comprises the gate logic unit has in one preferred embodiment smaller, or essentially the same, length and breadth as the extent of the electronic components of the reading head. In one embodiment of the present invention, the banknote reader is contained within a volume of (128 x 25 x 30) mm.
In this way, the volume of the reading head with the gate logic unit connected to it can be achieved in less than or equal to twice the volume of the actual reading head, which gives a compact banknote reader with much smaller dimensions than conventional readers. Furthermore, the data processing arrangement of the banknote reader can be manufactured integrated with the reading head of a banknote reader, with occupation of the minimum space possible in the vicinity of the feed input of a banknote reader.

Brief Description of Drawings

The text below will refer to the attached drawings in order to give a better understanding of the invention and its embodiments and the examples given, whereby:

Fig. 1 illustrates schematically a banknote reader with conventional data processing/image processing with DSP/CPU and software, in a side elevation and a block diagram.
Fig. 2 illustrates schematically the design of a banknote reader according to the prior art in perspective, in order to make clear its size.
Fig. 3 illustrates schematically a banknote reader according to the present invention, in side elevation.
Fig. 4 illustrates schematically the banknote reader according to Figure 3 in perspective.
Fig. 5 illustrates schematically how oblique feed and horizontal displacement of a banknote is detected/measured.

Detailed Description of Preferred Embodiments

The invention according to the present description is here described in the form of an FPGA gate logic unit solution, but the invention is not for that reason limited to comprising only such specific circuits, other alternative commercially available gate logic circuits can be used.
An FPGA is an integrated circuit comprising logical building blocks such as logic gates, memory cells, LUTs (look-up tables), inputs and outputs, etc. It is possible to construct a tailored circuit using these building blocks by connecting building blocks to each other. This has the advantage that the design is very flexible and it is easy to modify the design at a later stage. In order to achieve a banknote reader that carries out data processing/image processing using a gate logic unit such as an FPGA, knowledge is required both in programming and in hardware design, together with extensive knowledge of mathematics. A code or an algorithm must be "translated" into logical functions. While it is true that an FPGA is programmed using a high-level language VHDL (Very High Level Definition Language), this language is primitive In comparison with the programming ' language C.
There are advantages to using an FPGA for the design of a gate logic unit according to the present invention. One important reason for selecting an FPGA solution is the lack of space available, and in particular the limited space available for electronic components in the vicinity of the transport band in existing feed arrangements for banknote readers. A second reason is that it is desirable to integrate the reading head and its electronic components for the reading of a banknote with the electronic components for data processing of a banknote that has been read.
Furthermore, an FPGA design is difficult to copy, since the logic, and thus the algorithm, for data processing is hidden in the circuit solution, something that may be important for, for example, preserving "know-how". Furthermore, it is difficult to transfer a written measurement method/algorithm (in a programming language) to pure logic, and this is the reason that currently existing banknote readers use DSP for data processing and image processing.
The concept "banknote reader" according to the present invention is broader than solely comprising a reader that reads money, it also comprises an arrangement for reading value coupons, bar-codes and other documents having a value. The banknote reader data processes the input signal and specifies as an output signal what the type of the denomination of the document is. In the same manner, the concept of "banknote" comprises also other value documents, such as value coupons, bar-codes, deposit receipts and similar documents, when it is used according to the present invention. The concept of "banknote" will in the further description in the present case include a value document, preferably of paper or a material similar to paper.
Figure 1 illustrates schematically the prior art for banknote readers. The banknote reader in Figure 1 comprises an image reader/reading head 10, with an electronic circuit board 12 integrated with the reading head 10 as is commercially available, for the reading and digitising of banknotes. The reading head 10 is connected to the circuit board 12 through a contact 14 in one possible embodiment. According to the prior art, the banknote reader has a data processing/image processing means 18 that consists of an input and output circuit board I/O 20 and a DSP/CPU 22. The reading head 10 with the circuit board 12 is shown schematically connected to the I/O circuit board 20 through a flat cable 26. The data processing/image processing means 18 is connected to, for example, a PC 24, or another suitable data processing arrangement, for display and for other data processing during the reading of banknotes. The reading head 10 with the circuit board 12 in Figure 1 have actual dimensions of 128 mm In length, 25 mm In breadth, and 15 mm in height.
In order to obtain an understanding of the size relationship between the reading head 10 and the data processing/image processing means 18 in Figure 1, these are shown in perspective in Figure 2, although no claim is made for the correct scaling of this figure, since the means 18 can differ from one manufacturer to another. The circuit board 12 has in Figure 2 been schematically drawn with dashed lines such that a viewer will be able to obtain an impression of how the circuit board 12 has been placed on top of the reading head 10. In reality, the dimensions of the circuit board 12 essentially agree with the dimensions of the upper surface of the actual reading head 10, such that the electronic components in the circuit and the circuit board 12 lie essentially within the boundaries of the reading head 10.
Figure 3 illustrates schematically a banknote reader according to the present invention where the data processing/image processing means 18 has been replaced by a gate logic unit 32, preferably an FPGA, that is supported by a circuit board 30, shown dashed in Figure 3 as was the circuit board 12, which in one embodiment of the invention is connected to the electronic circuit board 12 of the reading head through a board-to-board connector 28. The circuit board 30 with the gate logic unit 32 can essentially agree with the size of the electronic section or the circuit board 12 of the reading head, whereby there is space within the boundaries of the reading head 10 for also the logic on the circuit board 30, as is the case for the circuit board 12. This is made most clear in the side elevation according to Figure 3. The banknote reader according to the invention has dimensions of 128 mm in length, 25 mm is breadth and 25 to 26 mm in height in one embodiment comprising the reading head 10, the circuit board 12 and the circuit board 30 with the gate logic unit. Thus, the banknote reader according to the invention has only increased its dimensions by approximately 10 mm in height, in comparison with the prior art as is illustrated in Figure 2. Data processing/image processing means 18 that are commercially available typically have dimensions of 100 x 100 x 100 mm.
Figure 4 illustrates the present invention schematically in perspective where the data processing/image processing means 18 has been replaced by the gate logic unit 32, whereby In contrast to the means 18 according to the prior art, the equivalent gate logic unit 32 is now integrated with the reading head 10, and space is available within the boundaries of the reading head. The gate electronic circuits 32 with the circuit board 30 have only Increased the height extent of the reading head such that the circuit boards 12 and 30 are located within essentially twice or less than twice the volume of the reading head, such as within the dimensions 128 mm in length, 25 mm in breadth, and approximately 25 to 26 mm in height, which constitutes a significant difference in space made available, when the banknote reader is mounted in the vicinity of a banknote feed for the reading of banknotes, when compared with the size relationship between the reading head 10 and the means 18 in Figure 2.
The embodiment of the image reader/reading head 10 that has been used to specify embodiments in the current description is of a linear type, i.e. it reads one line at a time, but other types of reading head are not excluded. All the lines are added in order to obtain a 2-dimensional image.
Naturally, one skilled in the arts within this technical area will understand that the boundaries of the reading head 10 do not have to be followed closely in all embodiments; such a person skilled in the arts will realise that other embodiments with respect to dimensions and design, which exploit the integration of the reading head 10 and the gate logic unit 32 on the circuit board 30, can be used. A person skilled in the arts will also realise that other connections between the reading head and the circuit boards 12 and 32 than the connectors 140, 16, 28 that have been specified in this description and that have been schematically drawn on the attached drawings can be used. Other embodiments of the reading head 10 that are commercially available are not excluded from being used to realise the present invention.
The resolution of the reading head is 200 dpi. The image reader/reading head 10 consists of an analogue linear element with the dimensions 128 mm in length, 25 mm In breadth, and 15 mm in height, and approximately 850 active points, with electronic components that compensate for deviations and that convert the signal to a digital format. Approximately 108 mm of the length of the linear element is used for scanning, something that allows adaptation to the widths of possible banknotes.
Broader readers are available such that it will be possible to read banknotes in a longitudinal direction. The image reader/reading head 10 is available with different LEDs: red, green, blue and infrared. It is sufficient to use solely IR for determining denominations. It is an advantage to examine a banknote under different illuminations for the purpose of authenticity control, not least to discover the possible presence of currency protection dye.
Banknote readers in general, and the banknote reader according to the present invention, have at least two purposes. It is to determine the denomination, such as SEK 20 or SEK 50, etc., of the banknote, depending on how many types of banknote a country or a community has, and it is to determine whether the banknote is authentic. Feed of banknotes into a banknote feed arrangement according to one preferred embodiment of the present invention does not depend on horizontal position, nor does it depend on angle. This means that a banknote 40 is fed in by hand, without for that reason it being necessary that the banknote should make contact with an edge. The ban knote can thus be fed in crooked or oblique. The algorithm/the electronic components for determination of the denomination and currency according to the present invention correct for all angular errors up to a value of +/- 15 degrees and for inaccurate horizontal feed of a banknote, something that is treated in a separate associated patent application with the same applicants as the present invention.
Algorithms for the determination of authenticity of banknotes are divided into determination of denomination and control of authenticity. The determination of denomination is based on the physical size of a banknote. Furthermore, a measurement method in the present invention corrects for any angular errors present if a banknote is fed in obliquely, and it corrects for any horizontal displacement from a reference plane, which is, as has been previously mentioned, described in an associated patent application, but which is, nevertheless, described here. Oblique feed or horizontal displacement of a banknote, see Figure 5, is determined by measuring the breadth of a banknote 40 at two locations or points separated by a distance x from each other. If the banknote is located obliquely or is displaced, the distance "a" will increase. The measurement of breadth is achieved from a reference plane 42, a reference line or another suitable reference. The actual/correct breadth is B and this can be calculated using the equation B = B' - f(a), where f is a function of a. The function f is constituted in one embodiment by a table with tabulated values for different values of a it will be realised that the equation can be solved by trigonometric calculations.
With respect to the analysis of authenticity, an authentic banknote has an IR signature that is unique for just that banknote. The infrared image is read Into a histogram, which is then compared with a typical histogram profile for just that denomination. If the signature of the banknote that has been read in agrees within certain limits with the preprogrammed histogram, the banknote is judged to be authentic.
The scope of the attached patent claims specifies further embodiments for one skilled in the arts in this technical area.

Claims

A banknote reader for at least one of denomination determination, authenticity control and image processing of a value document, comprising a reading head (10) with electronic components for the reading of a value document and a means for processing the data that has been read, characterized in that the reading head is connected to a programmable gate logic unit (32), which constitutes the said processing means, whereby the programmable gate logic unit (32) is integrated with the reading head (10) and for which space is essentially sufficient within the boundaries of the reading head, whereby space is essentially sufficient for the reading head 10 and the gate logic unit (32) within double the volume of the reading head (10), whereby the gate logic unit (32) is programmed with an algorithm for processing the data that has been read, and whereby at least one of either the denomination or the authenticity of a value document is determined with respect to predetermined conditions for the output signals of the gate logic unit.
The banknote reader according to claim 1, characterized in that the gate logic unit (32) is a "field programmable gate array" or similar.
The banknote reader according to claim 1 or 2, characterized in that the gate logic unit (32) is arranged on a circuit board (30).
The banknote reader according to claim 3, characterized in that the gate logic unit (32) with the circuit board (30) is connected to a board (12) of electronic circuits or to the electronic circuits of the reading head (10) through a board-to-board contact (28).
The banknote reader according to claim 3, characterized in that the circuit board (30) that comprises the gate logic unit (32) has a smaller breadth and length or a breadth and length that are essentially the same size as the extent of the electronic components of the reading head (10).
The banknote reader according to any one of claims 1-5, characterized in that the volume of the reading head (10) with the gate logic unit (32) connected to it is essentially less than or equal to double the volume of the reading head (10) alone.
The banknote reader according to any one of claims 1-6, characterized in that it is enclosed by a volume of 128 x 25 x 30 mm³.