EP2199986A1 - Method and device for recognising optical characteristics of a valuable document - Google Patents

Abstract

The method involves forming intensities of pulses at respective receiving signals representing positions. The memory cells are selected periodically for correction of receiving signals for pulse following one another. One of correction value is replaced by another correction value after selection. The correction values are stored in one of the memory cells. An independent claim is also included for a device for detecting optical characteristics of a valuable document.

Description

The present invention relates to a method and a device for detecting optical properties of a value document.

Under value documents are understood leaf-shaped objects that represent, for example, a monetary value or an authorization and therefore should not be arbitrarily produced by unauthorized persons. They therefore have features which are not easy to manufacture, in particular to be copied, whose presence is an indication of the authenticity, i. the manufacture by an authorized agency. Important examples of such value documents are chip cards, coupons, vouchers, checks and in particular banknotes.

Such value documents have characteristic optical properties for them. The properties may be absorption and / or transmission properties for optical radiation, which may vary locally on the particular document of value. Radiation in the IR range and / or in the visible range and / or in the UV range of the electromagnetic spectrum act. For example, the optical property may relate, inter alia, to a color distribution.

These optical properties can serve to identify the type of the respective value document and / or to check its authenticity. Since valuable documents can be soiled or damaged during use, it may also be necessary to determine the condition of the documents of value, in particular with regard to the optical properties.

Since an individual examination of documents of value, in particular banknotes, by hand is possible at best in individual cases, to check the type, the authenticity or state of the corresponding devices used to detect optical properties of a value document. Often, these are designed to capture the characteristics of a value document as it is transported past or through the device.

In one type of such devices, for the detection of color properties, the value document is illuminated with the same sequence of light pulses, the light of the pulses remitted in each case by the value document being measured with a suitable detection device. The pulses of the sequences differ in the color of the light, namely red, green and blue. By measuring the remitted radiation, color properties in the form of RGB properties can be measured in principle as optical properties. For different reasons, it may prove necessary to correct the color values determined by the detection device, for which purpose corresponding correction values are read from a correction value memory. The correction values can be determined, for example, as a function of the results of a calibration of the device. Powerful but inexpensive devices of the type mentioned are available, but allow only measurements with a small number of colors, typically RGB, optionally with an additional measurement for infrared pulses.

Especially for the examination of value documents but a higher number of measurement channels is desirable.

The present invention is therefore based on the object of specifying a method for detecting optical properties of a value document, which permits a simple detection of optical properties in a plurality of different Spectral ranges or colors only in remission or transmission or in remission and / or transmission permits, as well as to provide a corresponding device.

The object is achieved by a method for detecting optical properties of a document of value, in which pulses of sequences of pulses of optical radiation originating from the document of value are detected spatially resolved and locations on the document of value are formed which receive signals representing the strength of the pulses at the respective locations in each case one of the pulses for correcting the received signals at least one correction value from at least one memory location of a memory device is read, and the read at least one correction value is used to correct at least one of the received signals for the respective one of the pulses, the memory locations for correcting the received signals for successive pulses are cyclically read out and in which one of the correction values stored in one of the memory locations is replaced after reading for the correction of at least one of the received signals by another correction value.

The object is further achieved by a device for detecting optical properties of a value document having a detection device which, for the spatially resolved detection of pulses originating from the value document of sequences of pulses of optical radiation and forming locations on the value document, assigns the intensity of the pulses to the respective one Forming representative reception signals is formed, and a correction means for correcting the received signals, a memory means having storage locations for storing correction data for the correction of the received signals, and a processing means which is adapted for each one of the pulses for the correction of the received signals at least one correction value from in each case at least one memory location of the memory device to read, at least one of the received signals for the respective one of the pulses to form a corrected received signal using the read correction value to correct, said processing means reads out the memory locations for correcting the received signals of successive pulses cyclically and a replacement device which replaces at least one of the correction values stored in one of the memory locations after reading for the correction of at least one of the received signals for one of the pulses by another correction value. The device can be used in particular for carrying out the method according to the invention.

As already mentioned in the introduction, in the context of the invention optical radiation is understood as meaning electromagnetic radiation in the infrared, visible and ultraviolet range.

In the method, sequences of pulses of optical radiation originating from the document of value are detected. These may be, for example, remitted or transmitted pulses; the optical property can then be the remission or transmission. Furthermore, at least three of the pulses of each sequence preferably differ insofar as the received signals corresponding to these are to be corrected with respectively different correction values. However, it is also conceivable that luminescence should also be tested as an optical property and luminescence pulses are detected.

The pulses are detected in a spatially resolved manner, for which purpose the detection device can have a plurality of reception elements which receive optical radiation from different locations on the value document and correspondingly form the reception signals assigned to the locations. For example, a line-shaped arrangement of receiving elements can be provided for this purpose, which is arranged transversely or obliquely to the transport direction when transporting the value documents past the detection device.

Upon detection, the received signals representing the strength of the respective pulses are formed; the signals can be analog or digital. The strength of a pulse is understood in particular to mean the intensity of the pulse or the energy of the pulse. The receiving elements are preferably designed so that they are sensitive to the optical radiation of all received pulses, it being assumed that the spectral ranges of the pulses are predetermined. Furthermore, the detection device can have an optical system for imaging a region of the surface of the value document on the receiving elements and / or a receiving or signal processing device for processing the received signals, in particular for filtering, amplifying and / or digitizing. This optional processing of the received signals is understood as part of the formation of the received signals.

After the reception signals are formed, they are corrected using the correction values. The correction values are to be regarded as given. The device has this over the correction device.

For this purpose, it is assumed that for the pulses each of the sequences is known how to correct the corresponding received signals, ie which of the correction values are to be used.

At least two of the correction values are stored in the memory means and are read out according to the position of the pulses in the respective sequence for performing the correction.

For this purpose, the correction device has, in addition to the memory device, a processing device which can comprise, for example, a program memory with a program and a section of a microprocessor or microcontroller for executing the program. Depending on the embodiment, the section of the microprocessor or microcontroller may also perform a part of the signal processing of the received signals before the correction, for which purpose a corresponding program module must be provided. The memory device of the correction device can be separated from the microprocessor or microcontroller or preferably given by memory locations in the microprocessor or microcontroller. Preferably, however, the correction device is an application-specific integrated circuit (ASIC) or an FPGA, which may contain the memory device in particular.

The correction device, for example, the program for the microprocessor is now designed so that for each one of the pulses for correcting the received signals, which were formed in the spatially resolved detection of the pulse, at least one correction value is read from one memory location of the memory device. This storage space is thus used to store the correction value or the correction values for the received signals for the respective pulse. For successive pulses, the correction values to be used for the correction of the received signals of the respective pulses are cyclically read from memory locations of the memory device and used for correction, ie, for immediately consecutive pulses, different memory locations each become to the memory of the at least one correction value, ie the correction value or the correction values used. Thus, the number of correction values would be limited to the number of memory locations of the memory device.

In order to be able to process a larger number of pulses with different correction values, it is now provided that after reading out a correction value from one of the memory locations to correct a received signal, this is replaced by a further correction value to be used later. The term "after reading" is understood here only that the correction value will be replaced sometime after the current reading and before the next read out of the same memory location.

For this purpose, the device comprises the replacement device, which, depending on the design of the correction device, can be provided by a partial function of a microprocessor or microcontroller of the correction device or preferably as a separate device.

The processing of the received signals and the correction thereof are performed substantially in real time, i. the acquisition of pulses is not completed before the correction begins.

The replacement of the correction values makes it possible to use in the method a correction device which is actually intended only for processing a small number of correction values. In particular, for example, a correction device designed for three colors and optionally also IR radiation can be used to apply corrections for other colors as well. Since such simpler correction devices have a wider field of application and therefore in larger quantities can be produced, a device for detecting optical properties with a greater number of correction options can be provided easily and inexpensively.

Depending on the type of correction, the reading out and the replacement can take place in different ways.

In a first variant of the method, the same correction value can be used for correction of different locations of assigned received signals of the same pulse, wherein the received signals are corrected one after the other, and then the replacement of the correction value after reading for the correction of the last of the received signals for the same pulse can take place. In the case of the device, the correction device can be designed for this purpose to use the same correction value for correction of different locations of assigned receive signals of the same pulse, the receive signals being corrected one after the other and in which the replacement means are adapted to replace the correction value after readout for the correction of last of the received signals for the same pulse. For a pulse detected received signals that are assigned to different locations on the document of value are thus corrected with the same correction value, which is read one or more times from the same memory location. After reading out for the correction of the last of the received signals, the correction value is replaced. Whether a received signal corresponds to a pulse can be determined by means of the time interval of detection, but it is also a delineation by the device supplied trigger signals or the finding that received signals for all places, ie of all receiving elements, were formed possible. This alternative allows the use of a device in which replacement of the correction values can not be very fast.

According to a second variant, in the method for correcting different locations of assigned received signals of the same pulse, different correction values assigned to the locations can be used, each stored in the same memory location, and the replacement of the correction value can then be carried out after reading for the correction of one of the received signals for the same Pulse. In the apparatus, the correction device can be designed for this purpose to use different correction values associated with the locations, which are respectively stored in the same memory location, for correcting different locations of assigned receive signals of the same pulse, and the replacement means can be adapted to replace the correction value respectively after reading for the correction of one of the received signals for the pulse. Thus, in particular for each pulse for the locations or their associated receive signals, these associated correction values can be written into the same memory location, whereby the order of the correction values or the locations corresponds to the sequence of the received signals or the locations associated therewith. Thus, in particular, a correction for compensating for differences in the detection properties of the receiving elements can take place, even though the correcting device is present only over a small number of memory locations, in particular fewer than different receiver elements.

According to a third particularly preferred variant, in the method for correcting different locations of assigned received signals of the same pulse, different correction values assigned to the locations can be used, which are respectively stored in memory locations associated with the locations, and replacing the correction value for a location respectively after reading for the correction the received signal for the place and for the pulse takes place. For this purpose, in the apparatus, the detection device may comprise a predetermined number of receiving elements which each detect pulses originating from different locations and serve to form the reception signals associated with the locations, the memory device for each of the reception elements and thus each of the locations a predetermined number of memory locations for correction values The correcting device is designed to use, for correction of different locations of assigned received signals of the same pulse, correction values associated with the locations respectively stored in the memory locations associated with the locations, and in which the replacement means is adapted to replace the correction value for one Each place to perform after reading for the correction of the received signal for the location and for the pulse. In particular, memory locations assigned to each of the receiving elements can be present in the memory device and read out for the purpose of correcting the received signals formed by means of the receiving element. In this way, a location-dependent or for the receiving element individual correction is possible. The correction can take place for the locations independently of one another and in particular depending on the design of the correction device with respect to the locations serially or completely or partially in parallel.

The replacement of the correction values for different pulses can take place in at least two variants. In a first variant, the correction value for a location is replaced after it has been read out and before at least one of the correction values for the same pulse but another location is read out. In the second variant, the correction values for the locations are replaced after the correction values for the same pulse and all locations have been read out. In particular, the replacement can then take place as a "block".

The generation of the pulses originating from the value document can in principle be arbitrary. Preferably, in the method for generating the sequences of pulses, the value document is illuminated with corresponding sequences of illumination pulses of optical radiation, wherein at least two, preferably all, illumination pulses of a sequence by their type, in particular by the spectrum of the respective illumination pulse and / or the illumination direction of the respective illumination pulse relative to the value document, and the order of the pulses of different types of each of the sequences is predetermined. Preferably, at least one of the correction values used is then respectively assigned to one of the types of illumination pulses, so that the received signals are corrected with correction values which are assigned to the respective type of illumination pulses. The device may further include an illumination device for emitting illumination pulses of at least two different types, which may be given in particular by the spectrum of the respective illumination pulse and / or the illumination direction of the respective illumination pulse relative to the value document, and a control device for controlling the illumination device, the thereto is designed to control the illumination device so that they illuminate the value document with corresponding sequences of illumination pulses of optical radiation to generate the sequences, wherein at least two, preferably all, illumination pulses of a sequence by their type and the order of the pulses of different types each of The consequences are predetermined. Further, the processing means and the replacement means may be arranged so that each of at least one of the correction values used is associated with each of the types of illumination pulses, so that the reception signals are corrected with correction values respectively associated with the types of illumination pulses. The spectra of different In particular, types of illumination pulses may be selected to correspond to different colors. The type of illumination pulses can also be determined in particular by their spectrum and / or their illumination direction relative to the value document or the detection range of the detection device and / or their intensity. For emitting the illumination pulses, the illumination device can preferably have a plurality of optical radiation sources with predetermined spectra corresponding to the types and a controller for controlling the sources for emitting the sequence of illumination pulses. By illumination with an illumination pulse of one of the types, a corresponding pulse originating from the value document is generated, which is detected to form the corresponding received signal. The type of illumination pulse determines which optical property of the value document is detected, for example its reflectivity for light of color red, as predetermined by the illumination device. The correction now takes place using a correction value provided for the type or, in the case of a location-dependent correction, a plurality of correction values assigned to the type and assigned to different locations. The predetermined order of the illumination pulse types in the sequences determines the order in which pulses originate from the value document and thus receive signals are formed. This also determines which correction values are to be used to correct the received signals of the corresponding pulses. The control device need not only be designed to control the illumination device, but may also serve for synchronization of the function of the illumination device with that of the replacement device, depending on the design of the device.

The control device can in principle be designed as desired. For example, it can be given as a separate electrical or electronic circuit or by a corresponding serving only as a controller microcontroller or processor. Furthermore, it may comprise at least one circuit section of the detection device and / or the correction device and / or the replacement device. It is possible that the control means comprise a programmable portion of the detection means and / or the correction means and / or the replacement means and corresponding program instructions for execution by the programmable portion. Here, a programmable section is also understood to mean an FPGA. Particularly preferred is the embodiment in which the control means comprises a circuit portion or a programmable portion of the replacement means, since in this case the synchronization of the lighting pulse sequences with the replacement of the correction values can be made simple.

In the method, the correction values in the memory device can be read out and replaced in such a way that a received signal formed by illuminating the value document with one of the illumination pulses of one of the types is corrected with a correction value corresponding to the type and, depending on the embodiment, associated with the received signal. In the case of the device, the detection device, the correction device and the replacement device are preferably designed accordingly. In order to synchronize the illumination and the detection, in particular a synchronization device can be provided by means of which the delivery of the illumination pulses and the reception of the pulses coming from the value document are synchronized or synchronized with one another.

Preferably, in the method, the sequences of the illumination pulses are the same in terms of the type of pulses, and the number of pulses of a different type sequence is then preferably greater than the number of memory locations in the memory device, each for storing correction values for correcting Receive signals are used for the same place. In the apparatus, for this purpose, the illuminating means may be formed so that the output pulses are the same in terms of the type of the pulses, and the illuminating means and the memory means are arranged such that the number of pulses of a sequence of different types is larger than that Number of memory locations in memory that are used to store correction values to correct received signals for the same location. If, in particular, memory locations of the memory device are allocated to each of the receiver elements, then the number of these memory locations may be smaller than the number of pulses of a sequence of different types.

Furthermore, in the method, the respective correction value for replacing a read-out correction value may preferably be read from a further memory device separated from the memory device. In the case of the device, the replacement device may preferably have a further memory device separate from the memory device, in which correction values used for replacement are stored. While the memory device has to be a volatile memory in order to be able to replace the correction values, it is possible for the further memory device to use any type of memory which only needs to permit a sufficiently fast readout. As memory types for the further memory device are thus volatile and especially non-volatile memory into consideration.

In principle, the detection device, the correction device and the further memory device can be arranged as desired. In the device, however, it is preferred that electrical and / or electronic elements of the detection device and the correction device are designed as a module or assembly, and at least the further memory device, preferably the replacement device, is formed in another module or another module. A module is understood in particular to mean an arrangement whose elements are held on the same board. This embodiment has the advantage that detection means and correction means can be used as a finished assembly.

In particular, in the method in the further memory device more correction values can be stored than in the memory device and preferably as many correction values as are required for the correction of all received signals of a sequence. In the case of the device, more correction values can preferably be stored in the further memory device than in the memory device, and preferably as many correction values as are required for the correction of all received signals of a sequence. If the illumination pulses of a sequence differ in their types, in particular as many correction values may be required as different types of illumination pulses. In addition, if a correction depending on the location or the detecting receiving element, the number of correction values may be greater than or equal to the product of the number of types and the number of receiving elements.

In principle, the correction values used for the replacement can be kept arbitrarily ready. In the method, however, it is preferable to replace the correction values in the memory device with each other for replacement used correction values cyclically read from memory locations of the further memory device. In the apparatus, the replacement device may for this purpose preferably be designed so that it reads out the correction values used in each case for replacement cyclically from memory locations of the further memory device for replacing the correction values in the memory device. This embodiment has the advantage that it is easy to implement and in particular fast to perform. If a correction is also made with respect to the location, ie if different correction values are assigned to different locations, the cyclic readout preferably consists of reading the correction values for the types one after the other for each location. This can be done in succession or at least partially in parallel for different locations.

The illumination of the value document can in principle take place from only one side of the value document, wherein preferably its remission properties are detected. The illumination device is then designed such that it illuminates the value document with pulses when it is located in a detection range of the detection device in which the detection device can detect pulses originating from the value document, in particular also moves, and the detection device is designed such that this detects the remitted from the value document radiation of the pulses of the illumination device.

For the examination of value documents, however, it may also be desirable to check their optical properties for at least one spectral range both in transmission and in remission. In the method, the illumination pulse sequences can then each comprise at least one illumination pulse which is directed onto a first side of the value document and at least one further illumination pulse which is incident on a second, the first side opposite side of the value document. In the case of the device, the illumination device can be designed for this purpose such that the illumination pulse trains emitted by it each comprise at least one illumination pulse directed to a first side of the document of value and at least one further illumination pulse pointing to a second side of the document of value opposite the first side directed. For this purpose, for example, a radiation source may be provided, the illumination pulses of which are guided by a corresponding optical device into a first, leading to the one side or a second, leading to the second side beam path. However, the illumination device preferably has at least two radiation sources, at least one of which emits illumination sequences of the sequences on the first side of the value document in the detection area and the other illumination pulses of the sequences on the second side of the value document.

The value document can in principle rest relative to the device used for the detection upon detection. Preferably, however, a transport device is provided which transports value documents through a detection range of the detection device, in which the detection device can detect pulses originating from the value document.

The device according to the invention can be used in particular in devices for processing documents of value, in particular sorting devices and / or devices for accepting and / or dispensing banknotes. The subject of the invention is therefore also a device for processing value documents, in particular sorting devices and / or for accepting and / or dispensing banknotes with a device according to the invention.

Fig. 1

eine schematische Ansicht einer Wertdokumentbearbeitungsvorrichtung,

Fig. 2

eine schematische Ansicht einer Vorrichtung zur Erfassung optischer Eigenschaften eines Wertdokuments, die Teil der Wertdokumentbearbeitungsvorrichtung in Fig. 1 ist, von der Seite,

Fig. 3

eine schematische teilweise Ansicht der Vorrichtung in Fig. 2 entgegen der Transportrichtung des Wertdokuments, in der neben dem Transportpfad und dem Wertdokument darin nur Strahlungsquellen und Empfangselemente gezeigt sind.

Fig. 4

eine schematische Blockdarstellung einer Erfassungs-, einer Korrektur-, einer Ersetzungs-, einer Steuer- und einer Beleuchtungseinrichtung der Vorrichtung in Fig. 2,

Fig. 5

eine schematische Darstellung zur Veranschaulichung der Arbeitsweise der Vorrichtung in Fig. 2, und

Fig. 6

eine schematische Darstellung von Empfangselementen, Speicherplätzen einer Speichereinrichtung und Speicherplätzen einer weiteren Speichereinrichtung in einem zweiten Ausführungsbeispiel für Vorrichtung zur Erfassung optischer Eigenschaften eines Wertdokuments, die als Teil der Wertdokumentbearbeitungsvorrichtung in Fig.1 dienen kann, und

Fig. 7

eine Fig. 5 entsprechende schematische Darstellung zur Veranschaulichung der Arbeitsweise einer Vorrichtung eines weiteren Ausführungsbeispiels.

The invention will be further explained by way of example with reference to the drawings. Show it:

Fig. 1

a schematic view of a value-document processing device,

Fig. 2

a schematic view of an apparatus for detecting optical properties of a value document, the part of the value-document processing device in Fig. 1 is, from the side,

Fig. 3

a schematic partial view of the device in Fig. 2 contrary to the transport direction of the value document, in which only radiation sources and receiving elements are shown in addition to the transport path and the value document therein.

Fig. 4

a schematic block diagram of a detection, a correction, a replacement, a control and a lighting device of the device in Fig. 2 .

Fig. 5

a schematic representation for illustrating the operation of the device in Fig. 2 , and

Fig. 6

a schematic representation of receiving elements, memory locations of a memory device and memory locations of a further memory device in a second embodiment of apparatus for detecting optical properties of a value document, which as part of the value-document processing device in Fig.1 can serve, and

Fig. 7

a Fig. 5 corresponding schematic representation to illustrate the operation of a device of another embodiment.

A value-document processing device 10 in FIG Fig. 1 In the example, a banknote processing device has in a housing 12 via an input tray 14 for the input of value documents to be processed 16, in the example banknotes, a singulator 18, which can access value documents 16 in the input tray 14, a transport device 20 with points 22 and in branches of a given by the transport means 20 transport path 24 after the switches 22 each output compartments 26 for receiving processed by the value-document processing device 10 value documents with stacker wheels arranged in front of 28 further has the bank note processing device 10 along the path given by the transport device 20 transport path 24 one before the points 22 arranged sensor arrangement 30 for detecting properties along the transport path 24 transported banknotes 16 and a control and evaluation device 32, the verbun at least with the sensor assembly 30 and the switches 22 via signal connections is and is for evaluating at least one property of a detected by the sensor array 30 value document 16 reproducing sensor signals of the sensor assembly 30 and driving at least one of the switches 22 is formed in response to the result of evaluation of the sensor signals.

The sensor arrangement 30 in this embodiment comprises a sensor 34 for detecting optical properties of the banknotes. The sensor arrangement may further include, for example, a in Fig. 1 not shown ultrasonic sensor for detecting the state of documents of value, for example the presence of adhesive strips.

The control and evaluation device 32 detects the signals of the sensor assembly 30 and checks in the example on the basis of the signals of the sensor 34 and if any other sensors of the sensor assembly 30, if the optical properties of the document value predetermined criteria, for example, with respect to contamination and / or Authenticity, correspond and / or which denomination has detected by the sensor assembly 30 banknote 16. It can also check whether the banknote has at least one predetermined criterion in each case in a marketable, i. is still suitable for further use as a means of payment, state. Depending on the result of the test, the control and evaluation device 32 controls at least one of the switches 22 so that the value document or the banknote 16 from the transport device 20 into a certain predetermined type of value documents or banknotes associated with the test result corresponding output tray 26 promoted and stored there.

The sensor 34, which constitutes a device for detecting optical properties of a value document, together with an only schematically illustrated section 36 of the transport device 20 in FIG Fig. 2 shown schematically. The device 34 is designed to detect optical properties of a value document in different optical spectral ranges in remission and for optical radiation in the infrared range in transmission. In other embodiments, all colors could also be measured in transmission.

In the Fig. 2 and 3 more precisely schematically shown device 34 comprises a lighting device 38 for emitting illumination pulses of different types, a detection device 40 for detecting optical radiation emanating from a illuminated by the illumination pulses of the illumination device 38 value document 16, and forming corresponding received signals, a correction device 42 for correcting the Receiving signals depending on the types of illumination pulses, with which the value document was illuminated during the detection of the optical radiation, a replacement means 44 for the replacement of correction values in the correction means and a control means 46 for controlling the illumination means 38 and for synchronizing the function of the illumination device 38 with that of the replacement device 44.

The device 34 is designed to examine the optical properties of value documents with more than four different types of illumination pulses of optical radiation, in the example six types. The types differ by the spectra of the respective radiation in combination with the direction in which the radiation is emitted onto the document of value. The types generally referred to as BT comprise the illumination for a remission measurement with red, green and blue optical radiation and infrared radiation (IR) radiation and the combination of R, G and B colors and illumination for transmission measurement with infrared radiation.

For this purpose, in the example for the remission measurement, the illumination device 38 has radiation sources 50, 50 'and 50 "for each of the same side of the transport path section 48 given by the transport device for red, blue and green light, ie radiation with one Spectrum that corresponds to a red, blue or green color. The exact properties of the spectra are derived from the type of radiation sources 50, 50 'and 50 ", in the example corresponding light-emitting diodes .. Furthermore, a source 52 for the IR radiation is arranged on the same side of the transport path.

The radiation of these sources 50, 50 ', 50 "and 52 is represented by a in Fig. 3 not shown common first illumination optics 54 of the illumination device 38 bundled on the transport path section 48, so that on a document of value in the transport path section 48, a transversely to the transport direction T of the documents of value extending strip emerges as a lighting pattern. In the example, the direction of the beam path with respect to the transport path section 48 is inclined.

On the opposite side of the transport path 48 or document of value has the illumination device 38 for the transmission measurement as a further radiation source 56, a radiation source for IR radiation, in the example as the source 52 an IR light-emitting diode, arranged, the radiation by a in Fig. 3 not shown second illumination optical system 58 is bundled onto the transport path section 48, so that on a document of value in the transport path section 48, a transversely to the transport direction T of the documents of value extending strip emerges as a lighting pattern. The radiation source 56 and the second illumination optics 58 are arranged so that the IR radiation substantially orthogonal to a plane of the transport path section 48 and a value document 16 therein falls.

The lighting device 38 is controlled by the control device 46 described in more detail below, so that these or their radiation sources 50, 50 ', 50 ", 52 and 56 sequences of illumination pulses optical Radiation on the value document 16 outputs. Depending on the type of illumination pulse, the illumination pulses are remitted or transmitted by the value document 16, so that pulses originating from the value document 16 are generated by the illumination pulses by remission or transmission.

In order to detect the optical radiation, in particular the pulses, emitted by the value document 16 in the transport path section 48, more precisely the regions or strips illuminated by the illumination device 38, the detection device 40 has a device on the same side of the transport path as the radiation sources 50, 50 '. , 50 "and 52 arranged line scan camera 60, the receiving elements 62, such as CCD elements of a CCD array or CMOS photodetection elements, along a straight line arranged substantially transversely to the transport direction T and sensitive both in the visible and the infrared region of the electromagnetic spectrum , and one in Fig. 3 Capture optics 64, not shown, which focuses optical radiation coming from the value document 16 onto the line scan camera 60. For reading or receiving signals from the line camera 60, more precisely the receiving elements 62, the formation of received signals from the signals of the receiving elements 62 and optionally for preprocessing of the received signals, the detection device has a receiving unit 65. For each of the receiving elements 62, a received signal is formed, which reproduces the strength of the respective pulse at the location imaged by the receiver element 62 and is thus assigned to it. The detection device 44 is designed and arranged such that it detects both the area of a value document 16 illuminated in the transport path section 48 by the radiation sources 50, 50 ', 50 "and 52 and the area of the value document 16 from the radiation transmitted by the value document Radiation source 56 occurs or can occur. In the example, the illumination device 38 is designed so that overlap said areas, preferably at least partially cover. The detection optics 64 and the line scan camera 60 are arranged such that the received beam path defined by them extends at least approximately orthogonal to the value document 16 in the transport path section 48 and is aligned with the illumination beam path formed by the radiation source 56 and the second illumination optics 58.

The receiving elements 62 receive optical radiation coming from a value document and, depending on the intensity of the optical radiation and the spectrum of the radiation, form signals which represent the strength of the pulses and are preprocessed in the receiving unit. The signals represent the remission or transmission properties of the detected value document. The line scan camera is operated in a clocked manner, so that a locally resolved detection of the optical properties of the value document takes place through the transport of the value document past the line scan camera.

More specifically, the receiving unit 65 reads the signals of the receiving elements 62 in equal cycles, the detection for a receiving element taking place in each case for a predetermined period of time.

The receiving unit 65 also outputs clock signals which serve to trigger the delivery of the illumination pulses.

Since the receiving elements in different spectral ranges generally also have a different sensitivity, it is necessary to correct the received signals. For this purpose, the with the detection device 40 provided via a signal connection associated correction device 42, which is given in the present example by an application-specific integrated circuit. This has a memory device 66 (see. Fig. 4 ) with at least two, in the example four, memory locations 68 for correction values and a processing device 70 for the correction of received received signals with a correction value from one of the memory locations 68. The memory device is designed as a volatile memory.

In the example, the receiving unit 65 and the correction device 42 are formed in only one chip or in the same application-specific circuit.

By the receiving unit 65 to the correction device 42 emitted sequences of received signals are corrected by a respective received signal is corrected using a read from one of the memory locations 68 correction value. For the sake of simplicity, the received signals for different locations but the same pulse are referred to as the received signal group. The memory locations 68 are cyclically read out for the correction, so that one of the number of memory locations 68 corresponding number of successive received signal groups for different pulses, in Example 4, is corrected with the correction values stored in the memory locations. If E _{i denotes} the reception signal group of the reception elements 62 at the position i of the sequence and j the memory location (j = 1,..., N, in the example n = 4), then the reception signals of the reception signal group E _i are obtained using the current correction value in memory location j = 1, ie the value stored in read-out therein, the received signals of the received signal group E _{i + 1} using the current correction value in memory location j = 2, the received signals of Receive signal group E _{i + 2} using the current correction value in memory j = 3, the received signals of the received signal group E _{i + 3} using the current correction value in memory location j = 4 and the received signals of the received signal group E _{i + 4} using the current correction value in memory j = 1 corrected.

The correction device 42 then outputs the corrected received signals to the control and evaluation device 32, which reuses them.

The detection device 40 and the correction device 42 are in this example part of an assembly that does not include the replacement device 44, and arranged for example on a circuit board. They form a finished module 71, which is available for general use in the market.

In this form, the correction means 42 could use only a number of correction values corresponding to the number of memory locations 68, so that not all possible types of illumination pulses enabled by the illumination device could be used.

In the present example, however, the value document is to be illuminated with the same sequence of illumination pulses, each having six illumination pulses of different types, namely red, blue, green and infrared illumination pulses as well as red-green-blue mixed illumination pulses for the remission measurement and infrared illumination pulses for the transmission measurement ,

For the corresponding control of the illumination device and the necessary replacement of the correction values in the memory locations of the correction device 42, the replacement device 44 connected to the correction device 42 and the control device 46, which can be arranged on another circuit board, serve.

The replacement device 44 has a further memory device 72 for storing correction values for the types of illumination pulses used in the detection of the optical properties, in the example thus six. The memory device 72 is in the example a non-volatile, rewritable memory, for example an EEPROM or a flash memory. The replacement device 44 further has a processing unit 74, in the example a microprocessor or microcontroller, and a program memory in which program code is stored, in the execution of which the microprocessor or microcontroller carries out the replacement method described below.

The control device 46 connected to the illumination device 38 for driving thereof is connected to the replacement device 44, in this example in the form that corresponding program code for the microprocessor or microcontroller for controlling the illumination device is stored in a memory section in the execution of which the microprocessor resp Microcontroller controls the lighting device 38 for the delivery of illumination pulses of predetermined types.

For synchronization with the detection and correction device 40 or 42, the replacement device 44 and the control device 46 are connected to the correction device 42. In the example, for this purpose, the microprocessor or microcontroller is connected to a corresponding output of the correction device 42, are output via the triggered by the detection device 40 clock signals.

The detection and correction means 40 and 42 and the replacement and control means 44 and 46, more precisely their program code, are in this example designed so that all received signals of a received signal group, ie those for the same pulse, are corrected with the same correction value , The device operates as follows, partially and schematically in FIG Fig. 5 is illustrated.

Successive work cycles are in Fig. 5 from top to bottom consecutively represented by corresponding lines. The left-hand column shows which type BT is emitted by the illumination pulse, the middle table shows the occupancy of the memory locations 68 and the memory device 66 with correction values which are characterized by the type of illumination pulses in the generation of the receive signals of the received signal group to be corrected with them the right table shows the correction values from the further memory device 72, wherein their memory locations are also numbered. The left-hand column of this right-hand table shows the correction value used in each case for replacement, again characterized by the corresponding type of illumination pulse, and the right-hand column the memory location in the further memory device 72.

The correction device 42, triggered by the detection device 40, outputs clock signals to the replacement and control devices 44 and 46, more precisely the microprocessor or microcontroller.

This controls as a control device 46 in response to the clock signals to the illumination device 38 so that it outputs equal sequences of illumination pulses. Each clock signal corresponds to a lighting pulse. Each of the sequences F comprises different illumination pulses Types BT. In the example, the control device 46 initially controls the radiation sources 50, 50 'and 50 "and the beam source 52 to form a sequence F on successive clock signals, so that one red, one green, one blue and one infrared illumination pulse (for each clock signal). R, G, B, IR), then controls the radiation sources 50, 50 'and 50 "together in response to the following clock signal, so that an illumination pulse (RGB) with radiation from the three radiation sources is emitted onto the document of value. The radiation source 56, which as the last illumination pulse of the sequence F emits an IR illumination pulse (IR-TRA) for a transmission measurement, is then driven onto the following clock signal. These consequences F are in Fig. 5 illustrated in the left column.

The correction means 42 are on control by the detection means 40 from the signals via the replacement means 44 to the control means 46 so that during the delivery of the corresponding illumination pulse detected by this generated, from the document of value pulse is detected and converted into a received signal group. The received signals of this group are corrected by the correction device 42, which cyclically reads out the correction values in the memory locations 68 in order to correct successive received signals of the received signal groups, as described above.

After delivery of an illumination pulse and use of the correction value in the corresponding memory location for a received signal group, the replacement device 44 reads out a new correction value from the further memory device 72 and writes it to the last read memory location of the memory device 66 Fig. 5 This is illustrated by the fact that the table cell uses its content most recently for correction has been dotted, the new correction value used for replacement is indicated by an arrow.

In the method, in order to replace the correction values in the memory device, the correction values used in each case for replacement are cyclically read from memory locations of the further memory device.

More precisely, the control device 46 controls the illumination device 38 so that it emits a lighting pulse sequence F, which successively illumination pulses of the types R, G, B, IR, RGB and IR-TRA has. In the further memory device 72 correction values for the correction of received signals of received signal groups are stored in memory locations 1 to 6, which are detected when illuminated by illumination pulses RGB, IR-TRA, R, G, B, IR. This corresponds to the sequence of the types of illumination pulses as often cyclically permuted as the number of illumination types BT and the number of memory locations 68 differ.

The replacement device 44 then needs to read out the memory locations of the further memory device 72 only cyclically and to write the contents in each case to the last-read memory locations 68 of the memory device 66.

In this way it is possible to make corrections for more lighting pulse types than is actually intended for the detection and correction module.

A second embodiment differs from the first embodiment in that the correction of the received signals in dependence on the associated location or serving to form the received signal receiving element. These are the correction device, in particular Its memory device, as well as the replacement device with the further memory device compared to the first embodiment modified. The other parts are unchanged, so that the same reference numerals are used for these as in the first embodiment and the statements on these apply accordingly here.

The assignment of receiving elements or locations, the memory locations of the memory device and those of the further memory device are in Fig. 6 illustrated. For the sake of clarity, only three receiving elements are shown, four memory locations and six further memory locations for each of the three receiving elements.

The memory device 66 'now has four memory locations for each of the receiving elements 62, in which correction values for correcting the received signals formed by the respective receiving element can be stored. The correction device 70 'differs except by the modified memory device 66' in that now the received signals of each of the receiving elements are individually corrected by cyclic read out the correction values from the memory element or the corresponding locations memory locations for each of the received signals and used for correction become. This is done as in the first embodiment, but individually for each of the locations or each of the reception elements.

The further memory device 72 'of the modified replacement device 44' now has six memory locations for each of the receiving elements or each of the locations in which the correction values for the six types for the respective receiving element or the respective location are stored.

The substitution means 44 'is further arranged such that the replacement, as in the first embodiment for each pulse, but for all the locations, is now carried out separately for each of the locations or each of the reception elements. This means that for each of the locations or each of the receiving elements the in Fig. 5 is performed sequence, wherein a replacement after reading the respective correction value for the location in the correction device takes place.

The replacement of the correction values for different pulses can take place in two variants. In a first variant, the correction value for a location is replaced after it has been read out and before at least one of the correction values for the same pulse but another location is read out. In the second variant, the correction values for the locations are replaced after the correction values for the same pulse and all locations have been read out. In particular, the replacement can then take place as a "block".

Another embodiment differs from the first embodiment in that the replacement of correction values in memory locations 68 of the memory device 66 takes place before the next use thereof. For this purpose, the replacement device is modified accordingly. For example, it reads before the control for the nth illumination pulse of a sequence, in Fig. 5 For example, the second for a green illumination pulse, the corresponding correction value from the other memory device and writes it in the memory space, which is used to correct the received signals of the n-th receive signal group, in the example, the storage space n, for the second green illumination pulse so the memory space. 2 ,

In other embodiments, the replacement can be carried out in a corresponding manner at arbitrary points in time during the correction cycle to which the content of the respective memory location is not read.

Another embodiment differs from the first embodiment only in that an individual correction value is provided for each pulse or illumination type for each of the receiving elements 62 and thus each of the imaged locations.

If M, in the example M = 6, illumination pulse types and N receive elements are provided in the example, the replacement device now has a further memory device 72 'for storing the correction values, in which N * M correction values are stored (cf. Fig. 7 ). The correction values are respectively stored in M consecutive blocks with N memory locations, wherein in each block the correction values for the same type of illumination pulse and different reception elements 62, ie locations associated therewith, are stored. The order of the correction values in each block corresponds to the order in which the received signals for different locations but the same pulse are processed in the correction device.

A replacement of correction values now takes place after each readout of a correction value for the correction of a received signal.

More specifically, a correction value for a location and a given pulse in the same memory space is replaced by a correction value for another location but the same pulse as long as receive signals for different locations but the same pulse are corrected. In Fig. 7 , the Fig. 5 1, the correction values for the respective illumination pulse type for the different locations i are successively stored in the memory location which is used for the current pulse and which is shown in dotted lines. The storage takes place in each case after reading out the previous correction value and its use for correction. This is indicated by the index "_i" running from 1 to N. After reading out for the last received signal of the respective illumination pulse, the correction value, marked by "_N", first remains in the memory location and is first replaced after read-out, before the memory location for a corresponding illumination pulse is read out again. For the following illumination pulse, the correction value from the further memory device 72 'is written to the memory location before the correction value for the first received signal is read out, and thus the first location. This change with respect to the pulse types is carried out as in the first embodiment. In order to synchronize the replacement with the change of the received signals, a corresponding clock or signal connection between the receiving or the correction means and the replacement means is provided, via which the replacement means signals are supplied, by means of which the replacement means can control the time of replacement.

In other exemplary embodiments, the evaluation of the corrected received signals output by the correction device takes place in an evaluation device of the device 34, which then sends only a test signal to the correspondingly modified control and evaluation device 32, which represents the result of the test.

Further embodiments differ from the preceding embodiments in that the replacement and the control device 44 and 46 is not controlled by the correction device 40, but the detection device 42. It is also conceivable that the control device 46 is formed independently of the replacement device and is not driven by the replacement device 44, but directly by the detection or correction device. In this case, it is designed in coordination with the replacement means that they operate synchronized by the clock signals.

In further embodiments, larger numbers of illumination pulse types may also be used, for example, illumination pulses of a greater number of different colors or spectral ranges used for optical property detection only in remission, transmission only, or at least partially remission and transmission.

The correction values used in the respective exemplary embodiments can be determined using calibration methods known to the person skilled in the art.

Claims (21)

Method for detecting optical properties of a value document, in which
detected by the document of value pulses of sequences of pulses of optical radiation spatially resolved and places on the document of value associated, the strength of the pulses at the respective locations representing receiving signals are formed
for each one of the pulses for correcting the received signals, at least one correction value is read from in each case at least one memory location of a memory device, and
the readout at least one correction value is used to correct at least one of the received signals for the respective one of the pulses, the memory locations being cyclically read out for the correction of the received signals for successive pulses, and one of the correction values stored in one of the memory locations after reading the correction of at least one of the received signals is replaced by another correction value. Method according to Claim 1, in which the same correction value is used for the correction of different locations of assigned received signals of the same pulse, the received signals are corrected one after the other, and
the replacement of the correction value after reading takes place for the correction of the last of the received signals for the same pulse. Method according to Claim 1, in which correction signals assigned to the locations, which are respectively stored in the locations assigned to the locations, are used for correction of different locations of assigned reception signals of the same pulse, and the replacement of the correction value for a location in each case after readout for the correction of the reception signal for the place and for the pulse. Method according to one of the preceding claims, in which, to generate the sequences of pulses, the value document is illuminated with corresponding sequences of illumination pulses of optical radiation,
wherein at least two, preferably all, illumination pulses of a sequence differ by their type, which may in particular be given by the spectrum of the respective illumination pulse and / or the illumination direction of the respective illumination pulse relative to the value document, and the order of the pulses of different types of each of the sequences is given, and
in which in each case at least one of the correction values used is assigned in each case to one of the types of the illumination pulses, so that the received signals are corrected with correction values which are respectively assigned to the type of the illumination pulses. A method according to claim 4, wherein the sequences of the illumination pulses are equal with respect to the type of pulses, and the number of illumination pulses of a sequence of different types is greater than the number of memory locations in the memory means, each for storing correction values for correction of receive signals for the same location. Method according to one of the preceding claims, in which the respective correction value for the replacement of a read correction value from another, preferably separated from the memory device, memory means are read. Method according to Claim 6, in which more correction values are stored in the further memory device than can be stored in the memory device and preferably as many correction values as are required for correcting all received signals of a sequence. Method according to one of the preceding claims, in which, for the purpose of replacing the correction values in the memory device, the correction values respectively used for replacement are cyclically read from memory locations of the further memory device. Method according to one of the preceding claims, in which the illumination pulse trains each contain at least one illumination pulse directed to a first side of the document of value and at least one further illumination pulse directed to a second side of the document of value opposite the first side. Device for detecting optical properties of a value document, with
a detection device which is designed for the spatially resolved detection of pulses originating from the value document of sequences of pulses of optical radiation and formation of locations on the value document associated with the strength of the pulses at the respective locations representing receiving signals, and
a correction device for correcting the received signals, the one Memory device with memory locations for storing correction data for correcting the received signals, and a processing device which is set up to read at least one correction value from at least one memory location of the memory device for at least one of the pulses for correcting the received signals, at least one of the received signals for the respective one to correct the pulses to form a corrected received signal using the read correction value,
wherein the processing means cyclically reads out the memory locations for the correction of the received signals for successive pulses, and a replacement device which replaces one of the correction values stored in one of the memory locations after reading for the correction of at least one of the received signals by another correction value. Apparatus according to claim 10, wherein the correction means comprises, and is preferably provided by, an application specific integrated circuit. Apparatus according to claim 10 or 11, wherein the correction means is adapted to use the same correction value for correcting different locations of associated received signals of the same pulse, the received signals being corrected one after the other, and
wherein the replacement means is adapted to perform the replacement of the correction value after reading for the correction of the last of the received signals for the same pulse. Apparatus according to claim 10 or 11, wherein the detection means comprises a predetermined number of receiving elements, each detect pulses originating from different locations and serve to form the reception signals assigned to the locations, the memory device identifies a predetermined number of memory locations for correction values for each of the reception elements and thus each of the locations, the correction device is adapted to correct different locations of assigned reception signals of the same pulse to use respective correction values assigned to the locations, which are respectively stored in the memory locations assigned to the locations, and
wherein the substitution means is adapted to perform the replacement of the correction value for a location respectively after reading for the correction of the reception signal for the location and for the pulse. Device according to one of claims 10 to 13, further comprising an illumination device for emitting illumination pulses of at least two different types, which may be given in particular by the spectrum of the respective illumination pulse and / or the illumination direction of the respective illumination pulse relative to the value document, and a control device for Control of the illumination device, which is designed to control the illumination device so that it illuminates the value document with corresponding sequences of illumination pulses optical radiation to generate the consequences, wherein at least two, preferably all, illumination pulses of a sequence differ by the type and the order
the pulse of different types of each of the sequences is predetermined, and wherein the processing means and the replacement means are arranged so that each of at least one of the used correction values is associated with each of the types of illumination pulses, so that the received signals are corrected with correction values corresponding to the respective ones Types of illumination pulses are assigned. Device according to one of Claims 10 to 14, in which the control device comprises at least one circuit section of the detection device and / or the correction device and / or the replacement device or a programmable section of the detection device
and / or the correcting device and / or the replacement device and corresponding program instructions for execution by the programmable section. Apparatus according to any one of claims 10 to 15, wherein the illumination means is arranged to equalize the sequences of illumination pulses with respect to types of pulses, and
in which the illumination device and the memory device are designed such that the number of illumination pulses of a sequence of different types is greater than the number of memory locations in the memory device which are respectively used for storing correction values for correcting reception signals for the same location. Apparatus according to any one of claims 10 to 16, wherein the replacement means comprises a further memory means in which correction values used for replacement are stored and which is preferably separate from the memory means. Apparatus according to claim 17, in which electrical and / or electronic elements of the detection device and the correction device are designed as a module, and at least the further memory device, preferably the replacement device, is formed in another module. Device according to Claim 17 or Claim 18, in which more correction values can be stored in the further memory device than in the memory device and preferably as many correction values as required for the correction of all received signals of a sequence. Device according to one of Claims 17 to 19, in which the replacement device for replacing the correction values in the memory device cyclically reads out the correction values used in each case from memory locations of the further memory device. Device according to one of Claims 10 to 20, in which the illumination device is designed such that the sequences of illumination pulses output by it each comprise at least one illumination pulse directed to a first side of the document of value and at least one further illumination pulse which is directed to a second one addressed to the first page opposite side of the value document.

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