HK1158798A - Sensor device for the spectrally resolved capture of valuable documents and a corresponding method - Google Patents

Description

Sensor device for spectrally resolved recording of value documents and associated method

Technical Field

The invention relates to a sensor device for spectrally resolved detection of optical detection radiation, which is emitted by a value document transported in a predefined transport direction through a detection region of the sensor device, and to a method for detecting a movement and/or a position of a value document relative to a detection region of the sensor device.

Background

Within the scope of the present invention, a value document is understood to mean a sheet-like object which represents, for example, a monetary value or an authorization and which is therefore not to be arbitrarily produced by an unauthorized party. The value document therefore has features which are not easily producible, in particular not easily reproducible, and which are present as authenticity features, i.e. the production of said features is carried out by an authorized party. The main examples for such value documents are tickets, vouchers, checks and in particular banknotes.

Due to its value, value documents incur significant counterfeiting attempts, i.e. result in the unauthorized manufacture of documents with similar physical characteristics. To make this forgery difficult, value documents often contain only pigments and/or phosphors which are difficult to obtain and/or only rarely known with characteristic scattering or fluorescence spectra. In order to check the authenticity of the value document or the presence of forgery, the optical radiation emitted by the value document can be detected by a sensor device in a characteristic part of the spectrum of the light passing through the pigments or fluorescent substances and compared with a predefined spectrum.

In particular, such a document of value validation can be carried out mechanically, wherein the document of value is conveyed through the acquisition region of the sensor device. The acquisition region is defined here and in the following as the region from which the radiation emitted by the region is acquired and detected or measured by the sensor device. In mechanical testing, it is necessary to control the sensor device used in such a way that it captures the characteristics of the document of value when it is located in the capture region.

In this mechanical test, there is the problem that the detection characteristics of the sensor device may change over time or over a long period of operation. In particular, a shift of the spectrum to higher or lower wavelengths may occur, for example, i.e. a spectral line within the spectrum of a given substance may be detected at a wavelength shifted with respect to the actual wavelength corresponding to the spectral line. This property may influence the differentiation of genuine and counterfeit value documents. This disadvantage is exacerbated in particular when no corresponding movement is identified or not identified early.

Disclosure of Invention

The object of the invention is therefore to provide a sensor device for the spectrally resolved detection of optical detection radiation, which is emitted by a value document transported in a predefined transport direction through a detection region of the sensor device, wherein changes in the detection characteristics of the sensor device can be easily detected and preferably can be easily compensated for at least in part. Furthermore, a corresponding method should be given.

This object is achieved by a sensor device for spectrally resolved detection of optical detection radiation, which is emitted by a value document transported in a predefined transport direction through a detection region of the sensor device, comprising: a detection device for spectrally resolved detection of the detection radiation in at least one predefined spectral detection region and for generating a detection signal which describes at least one characteristic, in particular a spectral characteristic, of the detected detection radiation; at least one reference radiation device which emits optical reference radiation which is coupled at least partially into the detection radiation path of the detection device and which has a spectrum with structures in a predefined spectral detection region, in particular with at least one narrow band in a predefined spectral detection region, and/or with at least one edge in a predefined spectral detection region, and which has a radiation source which emits reference radiation or radiation of the radiation source for generating the reference radiation and which acts as an emitter of a light barrier (lichtschracke) or of an optical scanner (Lichttaster) which can be used to detect a movement and/or a position of the document of value relative to the detection region; and a control and evaluation device which is designed to receive and evaluate the detection signals of the detection device and to output evaluation signals depending on the evaluation result, and is further designed to use the detection signals which characterize the reference radiation for checking and/or for calibrating the detection device and/or for providing correction data which can be used to evaluate the detection signals which characterize at least one feature of the detection radiation emitted by the value document.

That is, the sensor device is arranged to spectrally resolve the optical characteristics of the value document transported in the predefined transport direction along the transport path. The actual acquisition is carried out here by a sensor device which is designed to spectrally resolve the optical radiation emitted by the value document in a predetermined spectral detection region (which represents the detection radiation) which is dependent, for example, on the characteristics of the value document to be examined. Spectrally resolved acquisition is to be understood here in particular as acquisition in a continuous wavelength range or in a plurality, preferably more than eight, wavelength intervals. For generating the detection radiation, the value document is illuminated, for example, with illumination radiation, which is reflected back, for example, more or less diffusely without wavelength changes, as detection radiation. In a corresponding configuration of the value document with at least one fluorescent feature, however, the value document can also be illuminated by an illumination radiation which excites the value document to emit fluorescent radiation which then forms the detection radiation.

The detection radiation reaches the components of the sensor device that cause spectral decomposition along the detection radiation optical path from the acquisition region, from which the spectral components reach at least one receiving or detection element of the detection device. The position of the acquisition region is given at least by the position and configuration of the detection means. The transport path and the transport direction are inter alia obtained by the position of the collecting area, the transport into this collecting area in such a way that the value documents should enter the collecting area in the area directly in front of it without lateral deflection, and (if the sensor device has a plurality of tracks) their position, etc.

The detection device may collect detection radiation from at least one segment of the value document that is within the collection area if the value document is transported along the transport path to the sensor device.

The reference radiation device serves to emit optical reference radiation which is coupled in the detection radiation optical path of the detection device and can therefore be collected spectrally resolved by the detection device. Optical radiation is understood here to mean radiation in the spectral region of ultraviolet, visible or infrared light. The coupling may be done anywhere in the detection radiation optical path that still allows spectral detection, but preferably the coupling is done so that the reference radiation comes from the acquisition area. The radiation path length of the reference radiation is determined to a large extent by the reference radiation device, but may also be determined in part by the position of the document of value. Depending on the embodiment of the reference radiation device and thus depending on the reference radiation optical path, the coupling can take place when there is no value document in the acquisition region or when there is a value document in the acquisition region. In a first case, the reference radiation at least partially arrives directly in the detection radiation optical path; in particular, the reference radiation path can be guided directly into the detection radiation path. In a second case, the scattering of the reference radiation by the section of the document of value located in the acquisition region can be achieved such that the scattered reference radiation reaches into the detection radiation optical path.

For generating the reference radiation, the reference radiation device has a radiation source which emits the reference radiation directly or the radiation of which can be used to generate the reference radiation, for example by illuminating a fluorescent reference material with the radiation of the radiation source.

Since the spectrum of the reference radiation is at least partially located in the spectral detection region of the detection device and thus of the sensor device and is predefined or known, the reference radiation can be used to: the optical characteristics of the test sensor device or the detection device, in particular the spectral characteristics thereof, are corrected, and/or data, in particular correction data, are provided, which are used when analyzing the detection signals in the examination of the document of value.

For this purpose, a control and evaluation device is provided which is connected to the detection device via at least one signal connection and which also evaluates the detection signals and outputs corresponding output signals when optical detection radiation from the value document is detected. The control and analysis device can in principle be constructed in any way and comprises in particular: a processor, a memory having stored therein a computer program which, when executed by the processor, performs the functions of the control and analysis device, an application specific integrated circuit and/or a programmable gate array, in particular a Field Programmable Gate Array (FPGA), or a combination of these components.

The spectrum of the reference radiation is given by the configuration of the reference radiation device, as will be further described below. The control and analysis means may use the detection signal directly or after conversion into data representing the characteristics of the detected radiation.

The radiation source of the reference radiation device furthermore serves as a light barrier or emitter of the optical scanner which can be used to detect a movement and/or position of the document of value relative to the detection region and thus for controlling the sensor device, in particular the corresponding component of the detection device which corresponds to the control and evaluation device. The radiation source thus fulfils a dual function, i.e. a source for generating the reference radiation or as a reference radiation source, and a light barrier or an emitter of the optical scanner. A light barrier is understood here to mean a device which comprises: the system comprises a transmitter for emitting optical radiation along a light barrier radiation optical path, a receiver for receiving radiation of the transmitter propagating along the light barrier radiation optical path and emitting a corresponding received signal, and at least one analyzing device connected with the receiver, the analyzing device analyzing the received signal of the receiver to determine whether the optical radiation emitted by the transmitter is blocked by an object along the light barrier radiation optical path and does not reach the receiver. Thus, the light barrier verifies whether the radiation optical path is interrupted by the object. The light barrier may be designed as a reflective light barrier or a unidirectional light barrier. The optical scanner includes: a transmitter for emitting optical radiation along an emission radiation optical path; a receiver for receiving optical radiation scattered by the object in the region of the optical path of the emitted radiation from the transmitter and for emitting a corresponding receiver signal; and at least one evaluation device connected to the receiver, which evaluation device determines whether an object is present in the beam path of the emitted radiation on the basis of the receiver signal and emits a corresponding signal.

By the dual function of the radiation source a simplified construction of the sensor device is obtained.

The above-mentioned object is also achieved by a method for detecting the movement and/or position of a value document relative to a detection region of a sensor device for spectrally resolved detection of optical detection radiation, which is emitted by a value document transported in a predefined transport direction through the detection region of the sensor device, wherein the sensor device comprises a detection device for spectrally resolved detection of the detection radiation in at least one predefined spectral detection region and for generating a detection signal, which describes at least one characteristic, in particular a spectral characteristic, of the detected detection radiation, in which method: transporting the value document along a transport path in a predetermined transport direction in a collection region of a sensor device; generating optical radiation which is at least partially directed onto the transport path of the value document such that it is suitable for detecting a movement and/or position of the value document relative to the detection region and which serves to provide reference radiation which is coupled in the detection radiation optical path of the detection device and has a spectrum with a narrow band lying in a predefined spectral detection region and/or has at least one spectrum with an edge lying in a predefined spectral detection region; collecting reference radiation from the collection area to form a detection signal characterizing the reference radiation and using the detection signal to perform an inspection and/or calibration of the detection device and/or to provide correction data usable in the analysis of the detection signal characterizing at least one characteristic of the detection radiation emitted by the value document; and collecting optical radiation from the transport path or reference radiation from the collection area and using it for collecting the movement and/or position of the value document relative to the collection area or for determining whether and/or when the value document enters the collection area and/or whether and/or when the value document is at least partially located within the collection area.

A characteristic of the reference radiation and in general a characteristic of the detection radiation is understood within the scope of the invention as a characteristic which can be represented by at least one numerical value.

The test is understood here to mean, on the one hand, a determination of whether the values of the acquired features corresponding to the reference radiation lie within a predefined tolerance interval. A corresponding signal may be generated based on the result of the determination. Within the scope of the present invention, the concept of testing is also understood to be calibration on the other hand. Calibration is understood to mean that under predetermined conditions, a relationship or deviation between a value of the acquired characteristic corresponding to the reference radiation and a predetermined, preferably known value of the characteristic of the reference radiation is determined and data representing the deviation or relationship is stored.

A correction, or calibration, is understood to mean a change in the sensor device, by means of which a deviation between a value corresponding to the characteristic of the acquired reference radiation and a predetermined, preferably known value of the characteristic of the reference radiation is reduced as far as possible.

The acquired characteristic of the detection radiation can also be used in the sense of a correction of the sensor device to perform a correction when analyzing the detection signal. For this purpose, in the method, data, hereinafter also referred to as correction data, are determined from the detection signal of the reference radiation, stored, for example, in a memory in the control and evaluation device, and are subsequently used when evaluating the detection signal when checking the value document. The determination of the data from the detection signals of the reference radiation can be carried out by a control and evaluation device designed accordingly for this purpose.

By using, in particular, narrow-band reference radiation or using reference radiation with edges in the spectrum, changes in the detection characteristics of the sensor device can be easily recognized.

The light barrier or the optical scanner must also have a receiver for the radiation of the radiation source. Different options are given for this. According to a first alternative, optical radiation that is not the reference radiation is used for the light barrier or the optical scanner. Furthermore, the sensor device as a light barrier or a receiver of the optical scanner can have at least one detection element, which does not belong to the detection device, for converting the radiation of the radiation source into an electrical reception signal, which does not receive the detection radiation. This achieves that the detection means are switched on only when in fact the value document is in the acquisition region. In this alternative, the reference radiation can in principle be coupled into the detection radiation path at will, and the coupling of the detection radiation into the detection radiation path preferably takes place depending on the position of the document of value relative to the acquisition region. This provides the advantage that reference radiation from the acquisition region can be coupled into the detection radiation optical path such that the relationship used for the examination of the detection device corresponds to the relationship when the features of the value document are actually acquired.

In another alternative, reference radiation is used as radiation for the light barrier or the optical scanner. In a first preferred embodiment, the receiver of the sensor device as a light barrier or light scanner can have at least one detection element, which does not belong to the detection device, for converting the radiation of the radiation source into an electrical reception signal, said detection element not receiving the detection radiation. In this embodiment, the coupling of the detection radiation into the detection radiation optical path can also take place in particular, but not absolutely necessary, depending on the position of the document of value relative to the acquisition region.

That is, in the method for detecting the movement and/or position of the document of value relative to the detection region or for determining whether and/or when the document of value enters the detection region and/or whether and/or when the document of value is at least partially located within the detection region, a detection element not belonging to the detection device, which does not receive detection radiation, can be used for converting optical radiation or reference radiation into an electrical reception signal from which the position or movement of the document of value can be determined, and in the method whether and/or when the document of value enters the detection region and/or whether and/or when the document of value is at least partially located within the detection region can be determined from the reception signal.

In this further alternative second embodiment, at least one part of the detection device within the sensor device serves as a light barrier or a receiver of the optical scanner. This allows the number of sensing elements to be kept low. In this case, in particular, the control and evaluation device can be further designed such that it determines from the detection signal of the detection device as the received signal whether and/or when the document of value has entered the acquisition region and/or whether and/or when the document of value is at least partially located within the acquisition region.

In the method, the reference radiation can be coupled into the detection radiation optical path at least partially depending on the position of the document of value relative to the acquisition region. For detecting the movement and/or the position of the document of value relative to the detection region, it can be determined from the detection signals of the detection device which characterize the reference radiation whether and/or when the document of value enters the acquisition region and/or whether and/or when the document of value is at least partially located within the acquisition region.

In particular, the reference radiation may be at least partially directed to the transport path of the value document such that the reference radiation is suitable for detecting a movement and/or a position of the value document relative to the acquisition region. The radiation formed by the reference radiation can then be detected before and/or for the subsequent acquisition of the spectral characteristics of the value document and used for the acquisition of the movement and/or position of the value document relative to the acquisition region.

In all alternatives, a transport path can in particular be associated with the sensor device, which transport path is provided for transporting the value document in a transport direction into the acquisition region and emits optical radiation in the direction of the transport path, preferably as reference radiation. The radiation source may emit its radiation, preferably a reference radiation, in the direction of the transport path. This allows a particularly simple construction of the light barrier or the optical scanner.

A particularly stringent test or calibration of the detection device or a stringent analysis of the detection signal is achieved if the reference radiation device is designed in the sensor device such that the bandwidth of the reference radiation spectrum in the spectral detection region is less than 5 nm. Accordingly, reference radiation whose bandwidth in its spectrum in the spectral detection region is less than 5nm is preferably used in the method. The bandwidth is here the full width at half maximum (FWHM).

As reference radiation means, in principle any means of emitting optical radiation with the required spectrum can be used.

The reference radiation can thus be formed, for example, by collecting a fluorescent sample with optical radiation in order to excite the emission of the reference radiation in the form of fluorescent radiation. For this purpose, the reference radiation device can have a fluorescent sample which can be excited by the optical radiation of the radiation source to emit reference radiation in the form of fluorescent radiation. This embodiment has the advantage that no high requirements are placed on the radiation source.

Preferably, however, the radiation source of the reference radiation device can be used directly as a reference radiation source for emitting reference radiation which, if appropriate after filtering, has a spectrum with a narrow band in the predetermined spectral detection region and/or has at least one spectrum with edges in the predetermined spectral detection region. By generating the reference radiation directly in the reference radiation source, it is possible to generate the reference radiation with known characteristics stably over a very long life, which is not necessarily the case when using fluorescent radiation of a fluorescent substance as the reference radiation. There is no fear of contamination of the fluorescent sample. For example, the reference radiation device can have a reference radiation source, preferably a light-emitting diode or a laser diode, and a narrow-band filter arranged behind it to generate the narrow-band reference radiation. In the method, optical radiation can accordingly be generated whose spectrum is at least partially located in the spectral detection region, and the radiation generated is narrow-band filtered to form the reference radiation.

Further, in a sensor device using a radiation source as a source of reference radiation, the source of reference radiation may comprise a temperature-stable edge-emitting laser diode or an edge-emitting laser diode with a wavelength-selective optical resonator, in particular with a high-quality resonator. In the method, the reference radiation can be emitted by at least one temperature-stable edge-emitting laser diode or edge-emitting laser diode with a wavelength-selective optical resonator, in particular with a high-quality resonator. Corresponding devices are basically known. A corresponding device is described in patent application DE 102005040821 a 1. When a resonator is used, the resonator has a characteristic frequency corresponding to the desired wavelength of the reference radiation.

In order to reduce the temperature influence, the radiation source for the reference radiation can alternatively also be a laser diode with "distributed feedback", a so-called DFR laser diode, or a laser diode with a "distributed bragg reflector", a so-called DBR laser diode, which does not have to be temperature-stabilized for the purposes sought here.

A simpler alternative is to use a radiation source as the source of the reference radiation in the sensor device, and the radiation source comprises at least one surface-emitting laser diode. In the method, the reference radiation is preferably generated by at least one surface-emitting laser diode. The use of such a laser diode provides equally more advantages. The laser diode therefore has a very narrow-band emission spectrum, so that preferably no filters or reference substances limiting the spectral bandwidth of the reference radiation are required between the reference radiation device and the detection device. Furthermore, the position of the ribbon is less sensitive to temperature effects than other types of laser diodes, so that no temperature stabilization is required. Furthermore, the radiation emitted by the surface-emitting laser diode is not very divergent. This has the advantage that no focusing optical elements or fluorescent substances for generating the reference radiation are required and are not provided in the sensor device, preferably after the surface-emitting laser diode in the radiation path, up to the detection device.

In principle any characteristic of the acquired reference radiation can be used. In particular, however, it is preferred for the acquisition of the spectrum to determine a spectral characteristic of the reference radiation as a characteristic of the reference radiation and to use it in the examination or correction or analysis. For this purpose, the control and evaluation device can furthermore be designed to determine spectral characteristics of the reference radiation as characteristics of the reference radiation and to use them when checking or correcting or determining the data for evaluation. In particular, it can be determined whether the detection signal, which describes the spectral characteristic of the reference radiation, corresponds within a predefined tolerance range to a known or predefined characteristic of the respective reference radiation, as determined by the reference radiation device and, if applicable, independently. As spectral features, the position or the center of gravity of a maximum of the spectrum determined around the band or edge in a predetermined wavelength range can be used in particular.

Alternatively or in combination, the intensity of the reference radiation can also be determined as a characteristic of the reference radiation and used when checking or correcting or determining the data for analysis. For this purpose, the control and evaluation device can be further designed in the sensor device to determine the intensity of the reference radiation as a characteristic of the reference radiation and to use it for testing or correction or evaluation. In this way, for example, the sensitivity of the detection device can also be determined, since absolute intensity values in the spectral detection region do not necessarily have to be used when analyzing the spectral features.

In particular, if a correction is desired, a spectrograph (spektrographische Einrichtung) with a field of detection elements and a spatial separation device which spatially separates the detection radiation into spectral components falling onto the field of detection elements can be provided in the sensor device, and the sensor device can further have at least one actuator which can be controlled by the control and evaluation device and which is mechanically coupled to the movably mounted field of detection elements or to at least one movably mounted optical element of the spectrograph which at least partially determines the position of the spectral components on the field of detection elements, in particular to the spatial separation device or the entrance slit. The control and evaluation device is designed for this purpose to control the actuator as a function of the detection signal for the coupled reference radiation, such that a deviation of the position of the spectral components of the reference radiation from a predefined position on the field of the detection element is reduced.

The characteristics of the detection device may depend on a number of factors. For example, in the method, the temperature of at least one part of the detection device and/or of at least one part of a reference radiation device for generating the reference radiation and/or of a temperature compensation element connected to the detection device and/or the reference radiation device can be recorded and used for checking or correcting or determining the data for analysis. The sensor device can have at least one temperature sensor connected to the control and evaluation device via a signal connection for recording the temperature of at least one part of the detection device and/or of at least one part of the reference radiation device and/or of a temperature compensation element connected to the detection device and/or the reference radiation device; the control and evaluation device can be designed in such a way that the acquired temperature is also used when checking or correcting or determining the data for evaluation. In this way, a separation of the different influences on the sensor device can be achieved.

But the temperature influence is not only present in the detection device. In many embodiments, the sensor device can comprise an illumination device which emits optical radiation for the acquisition of spectral characteristics of detection radiation, for example fluorescence radiation, emitted by the value document onto the value document located in the acquisition region, thus giving off the detection radiation. The temperature of at least one part of the lighting device for illuminating the acquisition area and/or the temperature of the temperature compensation element connected thereto can then be acquired and used in the verification or correction or determination of the data for analysis. The sensor device may thus have an illumination device for illuminating at least one part of the acquisition area and at least one temperature sensor connected to the control and evaluation device via a signal connection to acquire the temperature of at least one part of the illumination radiation device and/or of a temperature compensation element connected thereto; the control and evaluation device can additionally be designed for this purpose to use the captured temperature in the verification or correction or evaluation. In this way, the influence of the lighting device can also be taken into account, but wherein the influence here cannot be determined by using the reference radiation and the measurement in the detection of the radiation.

The invention can in principle be used for any sensor device of the aforementioned type. Preferably, however, a detection device having a spectral detection region with a bandwidth of less than 400nm is used as the detection device. Accordingly, in the sensor device, the detection device may be designed such that the spectral detection region has a bandwidth of less than 400 nm.

For the decomposition into spectral components, the detection device can have any, in particular also known, device or element. In particular, the detection device can have, for example, a dispersive element which diffracts in a predetermined spectral detection region. Examples of such elements are gratings, and in particular also imaging gratings.

Alternatively or additionally, the detection device may have, for example, a dispersive element that refracts in a predetermined spectral detection region. An example of such an element is a suitable prism.

The detection device can in principle have any receiving or detection element for capturing the spectral components spectrally resolved by the dispersive element, as long as the receiving or detection element is sensitive in the necessary spectral region. Preferably, for the detection of the spectral components of the detection radiation and the spectral components of the reference radiation coupled into the optical path of the detection radiation or the corresponding spectral components, a spatially resolved CMOS field, NMOS field or CCD field is used. The sensor device may accordingly have a spatially resolved CMOS field, NMOS field or CCD field to detect spectral components of the detection radiation and spectral components of the reference radiation coupled into the detection radiation optical path. The field is simply and inexpensively available.

Since the individual detection elements are read out one after the other in the CCD field, it is advantageous, in particular for fast detection, for the detection device to have an arrangement of individual detection elements whose signals can be read out independently of one another, preferably in parallel. In the method, an arrangement of individual detection elements whose signals are read independently of one another, preferably in parallel, is used for the detection of the detection radiation and the reference radiation and their spectral components, respectively. This embodiment not only allows for fast reading, but also allows matching the size and characteristics of the individual detection elements according to the desired spectral sensitivity. Possibilities relating thereto are described, for example, in the applicant's application WO 2006/010537 a1, the content of which is incorporated into the present description by reference.

The reference radiation device can be designed and arranged such that the reference radiation is coupled into the detection radiation path depending on the position of the document of value relative to the acquisition region. Two possibilities are conceivable in particular for this purpose. On the one hand, the reference radiation can be coupled-or after deflection-from the acquisition region into the detection radiation beam path by a corresponding design and arrangement of the reference radiation device, i.e. the normal detection radiation is coupled into the detection radiation beam path as in the case of the examination of value documents. If the value document is located within the acquisition region, the value document blocks the reference radiation and the reference radiation cannot be coupled into the detection radiation optical path. For this purpose, for example, a source of the reference radiation can be arranged opposite the detection device in the acquisition region with respect to the document of value. However, it is also possible to arrange the source of the reference radiation in the acquisition region on the same side as the detection device relative to the document of value and to have an optical element arranged on the opposite side which deflects the reference radiation in the direction of the detection radiation. The advantage of this alternative is that the reference radiation can be used directly.

On the other hand, the reference radiation device can be designed and arranged such that the reference radiation illuminates the value document located within the acquisition region and that radiation emanating from the illuminated region, i.e. the reference radiation scattered or reflected by the value document, is coupled into the detection radiation optical path. This alternative can be used if the sensor device should be arranged on only one side of the transport path for positional reasons.

The advantage of this alternative is that the reference radiation has practically the same optical path as the detection radiation and therefore a large part of the possible sources of interference of the detection device is collected.

Furthermore, the control and evaluation device of the sensor device can evaluate the detection signals in such a way that a detection of a movement and/or a position of the document of value relative to the acquisition region takes place before and/or after the determination of the at least one characteristic of the reference radiation. The light barrier or the optical scanner can thus be used for controlling the calibration of the inspection or sensor device or for the determination of the data for the analysis. In particular, the method can be configured to check and/or correct and/or determine the data for analysis each time a value document is identified as approaching or entering the acquisition area. Thus, each value document can be checked with high quality independently of the number of value documents checked directly one after the other.

But light barriers or light scanners may also be used in particular for controlling the acquisition of spectral features.

The intensity of the reference radiation can therefore be switched off or reduced and then switched on or increased again depending on the acquired position or movement of the document of value for at least one predetermined time period and/or depending on the detection signal. In the case of a sensor device, the control and evaluation device can be further designed to switch the reference radiation device to a stationary state and then to a working state again, depending on the acquired position or movement of the value document, for at least one predefined period of time and/or depending on the detection signal of the detection device. A rest state is understood here to mean a state of the illumination device in which no or reduced-intensity optical illumination radiation is emitted. In particular, the switching on to the standstill state preferably takes place after a predetermined time interval depending on the conveying speed; the time interval may be chosen such that subsequent detection of the spectral feature of the value document is not disturbed.

Further, after a predefined time interval after the entry of the value document into the acquisition area is recognized, preferably for illuminating the value document in the acquisition area, optical illumination radiation with a predefined minimum intensity in a predefined spectral illumination area can be generated and radiated into the acquisition area, and preferably the optical illumination radiation is switched off or reduced in intensity when the value document exits from the acquisition area. In the sensor device, the control and evaluation device is designed for this purpose such that, after a predetermined time interval following the recognition of the entry of a value document into the acquisition region, the illumination device is switched on to an operating state in order to illuminate the value document in the acquisition region with the optical illumination radiation in the predetermined spectral illumination region and preferably to switch the illumination device on to a stationary state when the value document leaves the acquisition region. The predefined time interval can be selected, for example, such that the acquisition of the characteristic of the reference radiation can take place during the time interval and/or a predefined region of the value document can be acquired using the sensor device after the time interval has elapsed. At least in the second case, the duration of the time interval depends on the transmission speed selection.

Drawings

The invention will be further explained below by way of example with reference to the accompanying drawings. The figures are as follows:

figure 1 shows a schematic view of a banknote sorting apparatus,

fig. 2 shows a schematic representation of the sensor arrangement of the banknote sorting apparatus shown in fig. 1, showing parts of the transport arrangement,

figure 3 shows a schematic illustration of a detection device of the sensor device shown in figure 2,

fig. 4 shows a schematic representation of a sensor arrangement of a banknote sorting apparatus according to a second embodiment, showing parts of a transport arrangement,

fig. 5 shows a schematic representation of a sensor arrangement of a banknote sorting apparatus according to a third embodiment, showing parts of a transport arrangement,

figure 6 shows a schematic representation of the detection means of the sensor means of the banknote sorting apparatus according to a fourth embodiment,

figure 7 shows a schematic representation of the detection means of the sensor means of the banknote sorting apparatus according to the fifth embodiment,

figure 8 shows a schematic representation of a sensor arrangement of a banknote sorting apparatus according to a sixth embodiment,

FIG. 9 shows a schematic representation of a sensor arrangement of a banknote sorting apparatus according to a seventh embodiment, showing parts of a transport arrangement, an

Figure 10 shows a schematic illustration of a sensor arrangement of a banknote sorting apparatus according to a further embodiment, showing part of the transport arrangement.

Detailed Description

The value document processing apparatus 10 shown in fig. 1, which comprises an apparatus for optically inspecting value documents 12, for example banknotes, has: an input box 14 for inputting documents of value 12 to be processed, a separator 16 which can grip the documents of value 12 in the input box 14, a transport device 18 with a switch 20 and a device 24 for checking documents of value arranged in front of the switch 20 along a transport path 22 given by the transport device 18, as well as a first output box 26 for identifying documents of value that are authentic and a second output box 28 for identifying documents of value that are not authentic behind the switch 22. The central control and output device 30 is connected in signal connection with at least the inspection device 24 and the switch 20 and serves to control the inspection device 24, to analyze the inspection signals of the inspection device 24 and to control at least the switch 20 depending on the result of the analysis of the inspection signals.

The inspection device 24 is connected to a control and evaluation device 30 for recording the optical characteristics of the value document 12 and for generating a test signal which describes these characteristics.

During the transport of the value document 12 through the transport path 22 in the predefined transport direction T at the predefined transport speed, the inspection device 24 captures the optical characteristics of the value document, wherein a corresponding test signal is formed.

Upon evaluation of the test signal of the test device 24, the central control and output device 30 determines from the test signal whether the value document is recognized as a genuine or non-genuine value document according to a predefined authenticity criterion of the test signal.

For this purpose, the central control and evaluation device 30 has, in particular in addition to the respective interface locations for the sensors, a processor 32 and a memory 34 connected to the processor 32, in which memory 34 at least one computer program with program code is stored which, when executed by the processor 32, controls the apparatus and evaluates the test signals and controls the transmission device 18 as a function of the evaluation.

In particular, the central control and evaluation device 30, and strictly speaking the processor 32 therein, can check an authenticity criterion, in which, for example, reference data for the value document to be considered authentic are contained, which are predefined and stored in the memory 34. Depending on the determined authenticity or non-authenticity, the central control and evaluation device 30, in particular the processor 32 therein, controls the transport device 18, strictly speaking the switch 20, such that the value document 12 is transported according to its determined authenticity for storage in the first output magazine 26 for value documents identified as authentic or in the second output magazine 28 for value documents identified as non-authentic.

The inspection device 24 comprises a sensor device for spectrally resolved detection of the optical detection radiation emanating from the value document 12 transported in the predefined transport direction T. In an example, the detection radiation is fluorescent radiation in the invisible region of the spectrum.

In the following, the sensor device 24, which is designated with reference numeral 24, is illustrated in more detail in fig. 2. The sensor device 24 comprises an illumination device 36 for illuminating at least part of a flat acquisition area 38 in the transport path 22, into which acquisition area 38 the value documents 12 to be examined on the transport path 22 arrive, and the sensor device 24 also comprises a detection device 40. The control means, in particular for controlling the lighting means 36, and the analysis means, in particular for processing and analyzing the detection signals of the detection means 40, are integrated in a control and analysis means 42, for example a programmable data processing means, said control and analysis means 42 in this example comprising a not shown processor and a not shown memory in which a program executable by the processor is stored for controlling the lighting means 36 and analyzing the detection signals of the detection means 40. The control and evaluation device 42 is connected to the central control and evaluation device 30 via a signal connection.

Furthermore, an optical scanner 44 having a transmitter 46 and a receiver 48 is provided, which optical scanner 44 is connected to the control and evaluation device 42 in order to control the transmitter 46 and to evaluate the signals of the receiver 48. In a further embodiment, the evaluation of the receiver signals can also take place by means of a separate optical scanner control device, the output of which is connected to the control and evaluation device 42.

The illumination device 36 serves to illuminate the acquisition region with optical radiation in a predetermined wavelength range, in this example in the infrared, and for this purpose has the field of identically designed surface-reflecting laser diodes ("vertical cavity surface emitting laser diodes" VCSELs ") as illumination radiation sources, which are likewise controlled in this example by the control and evaluation device 42 via corresponding signal connections. The radiation emitted from these laser diodes is referred to below as illumination radiation, which is collected by a not shown beam-collecting optics (strahlb n indelndex Optik) of the illumination device 36 into parallel radiation beams.

For illuminating the collecting region 38, the illumination radiation is deflected by a deflection element 50 of the detection device 40, for example a dichroic radiation element (dichroischen strahliter) which is reflective for the illumination radiation, toward a focusing optic 52, which focusing optic 52 focuses the illumination radiation on the collecting region 38. If the value document 12 is located within the acquisition area 38, the segments located within the acquisition area are illuminated in a corresponding illumination pattern.

The optical radiation excited by the illumination, which is in the form of fluorescent radiation in a spectral detection region predetermined by the type of the document of value or by luminophores present in the document of value, is in the detection radiation path which is emitted by the segments and which reaches the detection device 40 as detection radiation when the document of value 12 is an authentic document of value.

The detection device 40, which is illustrated in greater detail in fig. 3 for an exemplary embodiment, serves for spectrally resolved detection of the detection radiation in at least one predefined spectral detection region and emits a detection signal which describes at least one characteristic, in particular a spectral characteristic, of the detected detection radiation. This detection device is described in more detail in the present inventor's german patent application official document No. 102006017256, the contents of which are hereby incorporated by reference into this description.

In this exemplary embodiment, the detection device 40 comprises for this purpose a detection optics 54 and a spectrograph 56, which spectrograph 56 has a detector 58 for spectrally resolved detection of the spectral components generated by the spectrograph.

The detection optics 54 firstly have focusing optics 52 along the detection radiation path, said focusing optics 52 forming a collecting region towards infinity, i.e. the detection radiation from the collecting region 38 is converted into a parallel radiation beam, and the detection optics 54 have a selectively passing deflecting element 50 transparent to the radiation within a predetermined spectral detection region. The detection optics 54 further comprise condensing optics 60 for focusing the parallel detection radiation onto an entrance opening or entrance slit of the spectrograph 56. A filter 62 is optionally arranged between the collection optics 60 and the spectrograph 56 to filter out undesired spectral components from the detection radiation optical path, in particular spectral components in the wavelength region of the illumination radiation; and a deflection element 64 is arranged, which deflection element 64 is a mirror in the example, to deflect the detection radiation by a predetermined angle, for example by 90 degrees.

The spectrograph 56 has an entrance baffle 66, which entrance baffle 66 in an embodiment is provided with a slit-shaped baffle opening, which forms an entrance slit and whose longitudinal extension extends at least approximately perpendicularly to a plane defined by the detection radiation optical path.

The detection radiation entering through the baffle opening is bundled into a parallel beam by, for example, colorless collimating and focusing optics 68 of the spectrograph 56. The collimating and focusing optics 68 and the further optics are also only symbolically illustrated as lenses in the drawing, but in practice they are usually constructed as a lens combination. By "the optics are colorless" it is understood that it is corrected for color deviations in the wavelength region in which the spectrograph 56 operates. Corresponding corrections are not required in the further wavelength region. The entrance baffle 66 and the collimating and focusing optics 68 are arranged such that the baffle opening is at least very well approximately located in the focal plane on the entrance baffle side of the collimating and focusing optics 68.

The spectrograph means 56 further has spatially dispersive means 70, such as an optical reflection grating, which decomposes the incident detection radiation, i.e. the optical radiation from the collection area, into at least partially spectrally separated spectral components propagating in different directions depending on wavelength.

The acquisition device 58 of the spectrograph 56 has a detection apparatus 72, which detection apparatus 72 serves for the spatially resolved detection of spectral components in at least one spatial direction. During the detection, a detection signal formed by the detection device is supplied to the control and evaluation device 42, which collects the detection signal and compares the collected spectrum with a predefined spectrum on the basis of the detection signal. The control and evaluation device 42 is connected to the control device 10 in order to transmit the result of the comparison to the control device 10 by means of corresponding signals.

The spatial dispersion device 70 is in this example a reflective grating with a rectilinear structure, the straight line of which extends parallel to the plane through the longitudinal direction of the baffle opening and to the optical axis of the collimating and focusing optics 68. The linear spacing is selected such that the detection radiation can be spectrally resolved in a predetermined spectral detection region, for example in the infrared region. The dispersing device 70 is adjusted to this end in such a way that the separated spectral components, for example the first diffraction order, are focused by the collimating and focusing optics 68 onto the collecting device 58, in particular onto the detection device 72.

The detection device 72 has a line-shaped arrangement of detection elements 74 for the spectral components, which is oriented at least approximately parallel to the direction of the spatial decomposition of the spectral components, i.e., in this case parallel to the plane spanned by the spectral components, in this case exactly planar. Thus, the spectral components are imaged onto the detection device 72 by the collimating and focusing optics 68.

The detection elements 74 arranged in a row are designed such that their signals are readable independently of one another, preferably in parallel.

To achieve a structure that is as compact as possible, the dispersive device 70 is tilted in two directions with respect to the detection apparatus 72 and the direction of the detection radiation incident between the collimating and focusing optics 68 and the dispersive device 70 on the one hand. Since in the exemplary embodiment the direction of the detection radiation between the collimating and focusing optics 68 and the dispersing device 70 extends parallel to the optical axis of the collimating and focusing optics 68, the flat reflection grating 70 and therefore its linear structure is inclined in the plane of the optical path of the detection radiation with respect to the optical axis O of the collimating and focusing optics 68. Thus, at least in the region between the dispersive device 70 and the collimating and focusing optics 68, the face, e.g. the plane, generated by the spectral components is inclined by the angle α with respect to the direction of the detection radiation and the optical axis of the collimating and focusing optics. In particular, the normal of the flat reflection grating 70 is inclined by an angle α (see fig. 3) with respect to the optical axis O of the collimation and focusing optics 68 in the plane of the detection radiation path. Secondly, the dispersive device 70, strictly speaking the entrance slit of the specular (spekulare) reflection, i.e. the normal of the plane of the linear structure, here the reflection grating 70, is tilted at an angle with respect to the direction of the detection radiation between the collimating and focusing optics 68 and the dispersive device 70 and the optical axis O, so that the first order diffraction falls on the detection apparatus 72.

On the other hand, the rows of detection elements 74 of the detection device are arranged at least approximately in the plane of the baffle opening with the entrance baffle 66 and spaced apart from the baffle opening in a direction orthogonal to the plane defined by the propagation direction of the spectral components-above the baffle opening in fig. 3. In fig. 3, the receiving faces of the entrance baffle 66 and the detection element 74 are shown spaced apart from one another parallel to the focal plane of the collimating and focusing optics 68 for clarity, but in practice they lie substantially in a common plane. The baffle opening is located approximately in the middle of the row, as viewed in a direction parallel to the row of detector elements 74.

Upon detection, detection radiation emanating from a point on the document of value 12 in the acquisition region 38 is bundled along the detection radiation optical path by the focusing optics 52 into a parallel beam which enters through the dichroic radiation element and is imaged by the condensing optics 60 onto the entrance baffle 66. The detection radiation is imaged at infinity along a detection radiation path through collimating and focusing optics 68 onto a spatial dispersion device 70, which spatial dispersion device 70 decomposes the radiation impinging thereon into spectral components. The spectral components of the first order diffraction are again imaged by the collimating and focusing optics 68 onto the detection device 72, with each detection element 74 corresponding to a wavelength or wavelength region. The detection signal corresponding to the detection element describes in particular the intensity and power of the received spectral components. The detection device 40 supplies a detection signal corresponding to the spectral characteristic of the detection radiation to the control and evaluation device 42. The detection signal is received and analyzed by the control and analysis device 42.

The optical scanner 44 has, as an emitter 46, a radiation source in the form of a surface-emitting laser diode which emits optical reference radiation in a narrow-band wavelength region within a predefined spectral detection region, the full bandwidth at half maximum (FWHM) of which is 1 nm. For example, the maxima within the region may be at 760nm, 808nm, 948nm or 980 nm. The emitter 46 serves as a reference radiation device and a reference radiation source in this embodiment. The laser diode 46 is oriented toward the acquisition region 38 such that scattered reference radiation emitted within the acquisition region 38 from the fragments of the value document 12 illuminated therewith arrives at, i.e. is coupled into, the detection radiation optical path. The reflected part of the reference radiation reaches the receiver 48, i.e. a light-detecting element preceded by a baffle, which is sensitive in the region of the reference radiation and outputs a corresponding signal when the reference radiation is projected.

As can be seen from fig. 2, the reference radiation can be coupled in the detection radiation optical path and reach the receiver only when a section of the document of value 12 is within the acquisition region 38. The coupling thus depends on the position of the value document 12 relative to the acquisition region 38.

The sensor device 24 works as follows:

first, the optical scanner 44, the illumination device 36, and the detection device 40 are turned off.

If the control and evaluation device 42 detects a signal from a transport sensor, not shown, on the transport path, which signal indicates the arrival of the transported value document 12, the control and evaluation device 42 brings the transmitter 46, i.e. the reference radiation device, into an operating state in which the transmitter 46 emits reference radiation into the detection region 38.

If the receiver 48 does not detect the reference radiation after a time duration selected depending on the transport speed of the value document, the control and evaluation device 42 switches off the transmitter 46 again.

However, if the value document 12 is transported into the acquisition region 38 as intended, a portion of the reference radiation falling on the value document 12 is reflected in the direction of the receiver 48. If the receiver 48 detects the reference radiation and sends a corresponding signal to the control and evaluation device 42, the control and evaluation device 42 switches on the detection device 40 and collects the detection signals of the detection device 40 at least for the detection elements of the reference radiation onto which the correctly adjusted spectral components are to fall and the detection elements adjacent thereto.

Since the section of the document of value 12 within the acquisition region 38 is illuminated by the illumination radiation, the reference radiation scattered (e.g. scattered back) by the document of value 12 reaches into the detection radiation path and is split up into spectral components which are focused onto the detection device 72. This generates and sends to the control and analysis device 42 a corresponding detection signal which describes or represents a spectral characteristic of the reference radiation.

The control and evaluation device 42 receives the detection signal for a predetermined period of time, for example for a period of time which is selected as being necessary for the acquisition of a value document of 1mm depending on the transport speed, and determines whether the spectral characteristic represented by the detection signal meets at least one predetermined criterion. For example, the control and evaluation device 42 checks whether the maximum of the spectrum of the detection radiation determined on the basis of the detection signal lies within a predefined tolerance range of the maximum of the spectrum of the reference radiation emitted by the surface-emitting laser diode 46. If the test result is no, an error signal is output.

Otherwise, the transmitter 46 is turned off. The illumination device 36 is switched on after a predefined time period, which is also selected as a function of the transport speed, in which the detection signal is detected and the offset value is determined for the determination of the offset value, and the spectral characteristic of the value document is recorded. Here, each of the detection elements of the detection device corresponds to a wavelength or wavelength region.

After a further period of time has elapsed, which depends on the transport speed and on the length of the longest value document expected in the transport direction, the illumination device 36 and the detection device 40 are switched off again.

In the second embodiment of the sensor device 24' schematically shown in fig. 4, the difference from the first embodiment lies in the design of the optical scanner and the control and evaluation device 42. All further parts are unchanged so that the same reference numerals as in the first embodiment are used for these parts and the explanation thereof applies accordingly here.

In this embodiment, the detection device 40 assumes the role of a receiver of the optical scanner. Instead of the optical scanner 44, only a radiation trap (strahlungsfallel) 76 is now provided for the reference radiation reflected by the value document 12 in the acquisition region 38, which radiation trap 76 absorbs the respective reference radiation.

The control and evaluation device 42' differs from the control and evaluation device 42 of the first exemplary embodiment in that it controls the detection device 40 or evaluates its detection signals in such a way that the detection device 40 operates as a receiver of an optical scanner.

In more detail, the control and analysis device 42' is designed to carry out the following method.

If the control and evaluation device 42 'detects a signal from a transport sensor, not shown, on the transport path, which signal indicates the arrival of a transported value document 12, the control and evaluation device 42' brings the transmitter 46, i.e. the reference radiation device, into an operating state in which the transmitter 46 emits reference radiation into the detection region 38 and brings the detection device 40 into its operating state, as long as the detection device is not always in continuous operation. From this point in time, the control and evaluation device 42' collects the detection signals emitted by the detection device 40.

If the detection device 40 does not detect the reference radiation after a time period selected as a function of the transport speed of the value document and the control and evaluation device 42 'accordingly does not detect a detection signal caused by the detection radiation, the control and evaluation device 42' switches the transmitter 46 off again and switches off the detection device.

However, if the value document 12 is transported into the acquisition region 38 as intended, the segments of the value document 12 located within the acquisition region are illuminated by the reference radiation. The reference radiation scattered from the illuminated segments in the direction of the detection radiation path is coupled into the detection radiation path in the direction of the detection device 40 as a receiver and is split into spectral components, which are focused on the detection device 72. The detection device 40 generates a corresponding detection signal which describes or represents a spectral characteristic of the reference radiation and transmits it to the control and evaluation device 42'. The control and evaluation device 42' detects this detection signal and it first evaluates only whether a reference radiation has indeed been detected and, if necessary, confirms that the object was detected by the optical scanner.

The control and evaluation device 42' receives the detection signal for a predetermined period of time, for example within a period of time which is selected as necessary for the acquisition of a value document of 1mm depending on the transport speed, and further determines whether the spectral characteristic represented by the detection signal meets at least one predetermined criterion. For example, the control and evaluation device 42' checks whether the maximum of the spectrum of the detection radiation determined on the basis of the detection signal lies within a predefined tolerance range of the maximum of the spectrum of the reference radiation emitted by the surface-emitting laser diode 46. If the result of the check is no, an error signal is output to the central control and evaluation device 30, which central control and evaluation device 30 controls the display of a corresponding error message on a display, not shown.

Otherwise, the transmitter 46 is turned off. The following steps correspond to those in the first embodiment.

The third embodiment of the sensor device 24 ″ schematically illustrated in fig. 5 differs from the second embodiment only in that a light barrier is used instead of an optical scanner. This means that the reference radiation device and the control and analysis device are changed. All further parts are unchanged so that the same reference numerals are used for these parts and the explanations thereof apply correspondingly here.

The reference radiation device 46 ″ has the same surface-emitting laser diode as the reference radiation source 78 in the first two exemplary embodiments and has a deflection element 80, for example a mirror, which deflection element 80 deflects the reference radiation emitted by the reference radiation source and couples it into the detection radiation path if no document of value is located in the acquisition region 38. For this purpose, the deflecting element is arranged on the side of the transport path opposite the detection device 40.

The control and evaluation device 42 ″ is designed identically to the control and evaluation device 42', except for the modifications described below. In particular, the control and analysis device 42 ″ is designed to carry out the following steps.

If the control and evaluation device 42 ″ detects a signal from a transport sensor, not shown, on the transport path, which signal indicates the arrival of a transported value document 12, the control and evaluation device 42 ″ brings the transmitter 46, i.e. the reference radiation device, into an operating state in which the transmitter 46 emits reference radiation into the detection region 38 and brings the detection device 40 into its operating state, as long as the detection device is not always in continuous operation. From this point in time, the control and evaluation device 42 ″ receives the detection signals emitted by the detection device 40.

As long as no document of value 12 is located in acquisition region 38, the reference radiation emitted by laser diode 78 and deflected by deflection element 80 is coupled into the detection radiation beam path and is split into spectral components, which are focused onto detection device 72. The detection means 40 generate and transmit to the control and analysis means 42 "a corresponding detection signal which describes or represents a spectral characteristic of the reference radiation. The control and evaluation device 42 ″ detects this detection signal and determines whether the spectral characteristic represented by the detection signal meets at least one predefined criterion. For example, the control and evaluation device 42 ″ checks whether the maximum of the spectrum of the detection radiation determined on the basis of the detection signal lies within a predefined tolerance range of the maximum of the spectrum of the reference radiation emitted by the surface-emitting laser diode 78. If the test result is no, an error signal is output.

Otherwise, the acquisition of the detection signal is continued. The optical path from the deflecting element 80 to the detection device 40 is interrupted only when a value document enters the acquisition region 38. The control and evaluation device 42 ″ can now no longer receive a detection signal which represents the spectral characteristic of the reference radiation. The control and evaluation device 42 ″ thus continuously checks whether this signal is still present and, if this signal is not present, the control and evaluation device 42 ″ switches off the reference radiation device, for example the reference radiation source 78, since the control and evaluation device 42 ″ recognizes the entry of the value document into the acquisition region 38.

The illumination device 36 is switched on for a predetermined time period, which is selected as a function of the transport speed and in which the detection signal is detected and the offset value is determined, and the spectral characteristics of the value document are detected as described in the first exemplary embodiment.

After a further period of time, which depends on the transport speed and on the length of the longest value document expected in the transport direction, has elapsed, the illumination device 36 is switched off again and the reference radiation device 78 is switched on.

The fourth embodiment differs from the second embodiment in the design of the detection means and the control and analysis means shown in fig. 6. All further parts are substantially unchanged with respect to the design of the second embodiment or similar to the design of the second embodiment, so that the same reference numerals as in the second embodiment are used for these parts, respectively.

The detection device 82 differs from the detection device 40 in that instead of the collimation and focusing optics 68 an imaging grating in combination with a reflection grating 70 is used. Details concerning the detection device can be taken from the applicant's application WO 2006/010537 a1, the entire content of which is incorporated by reference in the present description.

Like the detection device 40, the detection device 82 has focusing optics 52, deflecting elements 50, condensing optics 60, filters 62 and deflecting elements 64, of course slightly rotated with respect to the positions in the first embodiment, all components being as designed in the first embodiment, and therefore the same reference numerals as in the first embodiment are used for them.

The spectrograph 84 of the detector 82 in turn has an inlet baffle 66 of the same design as in the first embodiment, for which the same reference numerals are used as in the first embodiment. As a spatial dispersion means, an imaging grating 86 is used, which imaging grating 86 performs a spectral decomposition of the detection radiation falling thereon by diffraction, and since the imaging grating 86 is designed as a concave mirror, it simultaneously performs an imaging of at least some of the spectral components of the detection radiation formed by the entrance slit formed by the entrance baffle 66 onto the detection means 58. The acquisition device 58 has a line-shaped detection device 88 of the spectrograph 84 or the detector 82, which detection device 88 is of the same design as the detection device 72.

Furthermore, the detection device 82 has a correction device which allows the position of the spectral components on the detection apparatus 88 or the position of the entrance slit of the entrance barrier for the image of the spectral components to be changed.

On the one hand, at least one suitable component of the spectrograph is mounted so as to be movable, preferably without play, for this purpose.

On the other hand, the detection device 82 has an actuator (or adjustment device) 90 which is mechanically coupled to at least one component of the spectrograph 84, for example to the spatial dispersion element 86, in order to change the predefined position of the spectral components generated by the spectrograph on the detection apparatus. The actuator 90 is connected to the control and evaluation device via a signal connection and, as a function of the actuating signal of the control and evaluation device, moves at least one component of the spectrograph, for example the spatial dispersion element 86.

In the example, the actuator 90 has a piezo element which allows a very precise movement of the component depending on the corresponding actuating signal. While it is theoretically more advantageous to rotate the imaging grating 86 in order to move the position of the spectral components on the detection device 88, in the present example the component is supported and the actuator is mechanically coupled to the component such that the component is linearly movable in a direction extending perpendicular to the optical axis of the imaging grating and parallel to the direction of decomposition of the spectral components. This support is basically a simple support that allows swinging.

The control and evaluation device 92 differs from the control and evaluation device 42' in that it not only carries out the checking of the detection device 82, but also carries out the correction. For this purpose, the control and evaluation device 92 is designed in particular to carry out the following method.

If the control and evaluation device 92 detects a signal from a transport sensor, not shown, on the transport path, which signal indicates the arrival of a transported value document 12, the control and evaluation device 92 brings the transmitter 46, i.e. the reference radiation device, into an operating state in which the transmitter 46 emits reference radiation into the detection region 38 and brings the detection device 82 into its operating state, as long as the detection device is not always in continuous operation. From this point on, the control and evaluation device 92 collects the detection signals emitted by the detection device 82.

If the detection device 82 does not detect the reference radiation after a time period selected as a function of the transport speed of the value document and the control and evaluation device 92 accordingly does not detect a detection signal caused by the detection radiation, the control and evaluation device 92 switches the transmitter 46 off again and switches it off.

However, if the value document 12 is transported into the acquisition region as intended, the segments of the value document 12 located within the acquisition region are illuminated by the reference radiation. The reference radiation scattered from the illuminated segments in the direction of the detection radiation path is coupled into the detection radiation path in the direction of the detection device 82 as a receiver of the optical scanner and is decomposed into spectral components, which are focused on the detection device 72. The detection means 82 generate and send to the control and evaluation means 92 a corresponding detection signal which describes or represents a spectral characteristic of the reference radiation. The control and evaluation device 92 detects this detection signal and therefore first evaluates whether a reference radiation has indeed been detected and, if so, identifies that the object was detected by the optical scanner.

If the optical scanner detects an object, i.e. a document of value, the control and evaluation device 92 detects further subsequent detection signals within a predetermined time period, for example within the time period required for detecting a 1mm document of value, which is selected as a function of the transport speed, and determines a deviation of the spectral characteristic represented by the detection signals from a spectral characteristic predetermined for the reference radiation, which is determined in this example by the surface-emitting laser diode 46. In the example, the control and evaluation device 92 precisely determines the deviation between the wavelength of the maximum of the spectrum of the detection radiation determined on the basis of the detection signal and the wavelength of the maximum of the spectrum of the reference radiation emitted by the surface-emitting laser diode 46. The control and evaluation device 92 need not necessarily determine the wavelength explicitly, but may also merely form the difference between the acquired position of the maximum value on the detection device 88 and a predefined position of the maximum value on the detection device.

Depending on the determined difference, the control and evaluation device 92 now controls the actuator 90 in such a way that the actuator 90 moves the component (here the dispersive element 86) such that the difference is reduced. For example, the amplitude of the movement can be selected to be proportional to the difference or read from a table in which the movement or adjustment signals necessary for a given difference are stored. This table can be determined experimentally or by calculation.

Thereby, a correction of the detection means is achieved.

Although only individual value documents are controlled in this way, a corresponding result can be achieved in the adjustment of the detection device when checking a plurality of value documents that follow one another quickly, since the influence that leads to an undesired misalignment changes only very slowly.

The steps of offset determination and acquisition of a detection signal representing a spectral feature of the fluorescent radiation correspond to the steps of the first embodiment.

In a modified variant, instead of adjusting the dispersive element, an adjustment of the entrance baffle 66, strictly speaking of the entrance slit, may be performed.

In a further variant, instead of at least one component of the spectrograph, the detection device 88 is mounted so as to be linearly movable in its longitudinal direction and is coupled to a corresponding drive for moving the detection device.

The corresponding adjustability of the spectrograph means is also applicable to the other embodiments.

The fifth embodiment of fig. 7 differs from the fourth embodiment in that the imaging grating is fixedly supported and the actuator 90 is eliminated; and on the other hand the design of the acquisition device 58, i.e. the design of the detection device 72 or the detection device 88. Furthermore, the control and analysis device is modified with respect to the fourth embodiment. The same reference numerals as in the fourth embodiment are used for the unchanged parts of the fourth embodiment, and the explanation thereof is applied accordingly here.

The detection device 88' comprises a line-shaped CCD field which extends in its longitudinal direction parallel to the direction of the spatial decomposition of the spectral components. The CCD field provides a high spatial resolution, for example a line shaped CCD field comprising 256 detector elements arranged in a line.

The control and evaluation device is now designed to determine correction parameters which can be used to correct the acquired test results. This is comparable to the calibration of the sensor device.

In particular, the control and analysis device 92' is designed for carrying out the following steps.

If the control and evaluation device 92 ' detects a signal from a transport sensor, not shown, on the transport path, which signal indicates the arrival of a transported value document 12, the control and evaluation device 92 ' brings the transmitter 46, i.e. the reference radiation device, into an operating state in which the transmitter 46 emits reference radiation into the detection region 38 and brings the detection device 82 ' into its operating state, as long as the detection device is not always in continuous operation. From this point in time, the control and evaluation device 92 'collects the detection signals emitted by the detection device 82'.

If the detection device 82 'does not detect the reference radiation after a time period selected as a function of the transport speed of the value document and the control and evaluation device 92' accordingly does not detect a detection signal caused by the detection radiation, the control and evaluation device 92 'switches the emitter 46 off again and switches off the detection device 92'.

However, if the value document 12 is transported into the acquisition region 38 as intended, the segments of the value document 12 located within the acquisition region are illuminated by the reference radiation. The reference radiation scattered from the illuminated segments in the direction of the detection radiation path is coupled into the detection radiation path in the direction of the detection device 82 'as a receiver and is split into spectral components, which are focused on the detection device 58 or the detection apparatus 88'. The detection means 82' generate and send to the control and evaluation means 92 a corresponding detection signal which describes or represents a spectral characteristic of the reference radiation. The control and evaluation device 92 collects this detection signal and it first evaluates only whether a reference radiation has indeed been collected and, if necessary, confirms that the object was collected by the optical scanner.

If the optical scanner detects an object, i.e. a document of value, the control and evaluation device 92' detects further subsequent detection signals within a predetermined time period, for example within the time period required for detecting a 1mm document of value, which is selected as a function of the transport speed, and determines a deviation of the spectral characteristic represented by the detection signals from a spectral characteristic predetermined for the reference radiation, which is determined in this example by the surface-emitting laser diode 46. In the example, the control and evaluation device 92' determines precisely on the basis of the detection signal for the reference radiation the detection element which has acquired the maximum intensity, i.e. the maximum of the spectrum. This is an implicit determination of the actual position of the maximum on the wavelength scale. When the correction data representing the detection device 82 'are well adjusted, the control and evaluation device 92' then stores the position of the maximum value or the deviation of the maximum value position from the maximum value setpoint position.

Alternatively, the wavelength of the maximum and the deviation from a predetermined wavelength of the maximum can also be determined and corresponding correction data stored.

The following steps of the offset determination are performed as described in the first embodiment.

The illumination device 36 is switched on and the spectral characteristics of the value document are collected. Here, each of the detection elements of the detection device corresponds to a wavelength or wavelength region. Now, when converting the detection signal into a wavelength, correction of the acquired spectrum is performed by using correction data corresponding to a shift in wavelength dependence, depending on the variant. This can be done, for example, in such a way that each of the detection elements corresponds to a corrected wavelength or a corrected wavelength range depending on the determined deviation or depending on the correction data. The resulting data can then be compared with the spectrum of the actual value document given in advance.

Alternatively, the predetermined spectrum can also be shifted by using the correction data after the detection signal has been converted into intensity as a function of wavelength or wavelength range.

After the passage of a corresponding time period, which depends on the transport speed and on the length of the longest value document expected in the transport direction, the control and evaluation device 92' switches off the illumination device 36 and the detection device 40 again.

The sixth exemplary embodiment in fig. 8 differs from the first exemplary embodiment in that temperature sensors 96 and 98 are arranged on the lighting device 36 and on the temperature compensation element 94 of the detection device 40, which should conduct the heat of the optical components and the detection device, which temperature sensors detect the temperature of the lighting device 36 and of the temperature compensation element 94 and thus of the detection device 40, and emit corresponding temperature signals to a control and evaluation device 100, which is connected to the temperature sensors via a signal connection.

The control and analysis device 100 is a combination of the control and analysis devices of the first and fifth embodiments. The control and analysis device 100 is designed identically to the control and analysis device 40 of the first embodiment with regard to the function of the optical scanner, and the control and analysis device 100 is designed identically to the fifth embodiment with regard to the determination and storage of correction data and the use of correction data. The control and evaluation device 100 is furthermore designed to detect the temperature signals of the temperature sensors 96 and 98 and to use these in the determination of the correction data and in the determination of the spectral characteristics of the detection signals of the detection radiation of the value document illuminated by the illumination device 36. For this purpose, the effect of the temperature change is stored in the control and evaluation device 100 in the form of temperature correction data, which can be obtained experimentally or by using models of the illumination device and the detection device.

The seventh embodiment in fig. 9 differs from the first embodiment only in that in the sensor device 24' ″, the illumination radiation is radiated obliquely onto the document of value and the detection radiation is correspondingly collected obliquely.

Further embodiments differ from the first embodiment in that as a radiation source, instead of a surface emitting laser diode, an edge emitting laser diode comprising a temperature stable edge emitting laser diode, a DFR or DBR laser diode or an edge emitting laser diode with a high quality optical resonator amplifying substantially only the desired reference radiation wavelength is included.

The further embodiment in fig. 10 differs from the first embodiment only in that the reference radiation is generated indirectly. Instead of the emitter 46, a laser diode 102 is used, whose optical radiation falls on a fluorescent sample 104 in a predetermined wavelength range of the reference radiation, which is located below the detection region in the radiation beam path, of the laser diode 102. This optical radiation of the laser diode is selected such that it excites the sample 104 to emit fluorescent radiation as a reference radiation in the above sense, which is then coupled into the detection radiation optical path.

In a further embodiment, the control and evaluation device is adapted such that it determines the total intensity of the reference radiation in addition to the spectral characteristics of the reference radiation and uses this total intensity in the verification, correction or determination of the correction data.

In a further embodiment, a detection device as described in WO 01/88846a1 may also be used, and a two-dimensional CCD field is utilized as the detection device, among others.

Although in the illustrated embodiment the reference radiation path length and the detection radiation path length extend at least partially parallel to or in the same plane, this need not be the case. For example, in the first embodiment, it is also conceivable that the plane determined by the optical scanner 44 and its radiation optical path extends orthogonally to the plane of the detection radiation optical path of the illumination and sensor arrangement shown in fig. 1.

Claims (49)

1. A sensor device for spectrally resolved detection of optical detection radiation, which is emitted by a value document transported in a predefined transport direction through a detection region of the sensor device, comprising:

a detection device for spectrally resolved detection of the detection radiation in at least one predefined spectral detection region and for generating a detection signal which describes at least one characteristic of the detected detection radiation,

at least one reference radiation device which emits optical reference radiation, which is coupled at least partially into the detection radiation path of the detection device and has a spectrum with structures in a predefined spectral detection region, and which has a radiation source which emits reference radiation or radiation of the radiation source for generating the reference radiation and which acts as a light barrier or a transmitter of an optical scanner which can be used to detect a movement and/or a position of a document of value relative to a detection region, and

a control and evaluation device, which is designed to receive and evaluate the detection signals of the detection device and to output evaluation signals depending on the evaluation result, and which is further designed to use the detection signals characterizing the reference radiation for checking and/or correcting the detection device and/or to provide correction data, which are used when evaluating the detection signals characterizing at least one feature of the detection radiation emitted by the value document.

2. The sensor device according to claim 1, further comprising as a light barrier or a receiver of the optical scanner at least one detection element not belonging to the detection device for converting the radiation of the radiation source into an electrical reception signal, which detection element does not receive the detection radiation.

3. The sensor device according to claim 1, wherein the coupling of the reference radiation into the detection radiation optical path takes place depending on the position of the document of value relative to the acquisition area.

4. The sensor device according to claim 1, further comprising as a light barrier or a receiver of the optical scanner at least one detection element not belonging to the detection device for converting the reference radiation into an electrical reception signal, which detection element does not receive the detection radiation.

5. The sensor device according to claim 1, wherein at least one part of the detection device serves as a light barrier or a receiver of a light scanner.

6. Sensor device according to claim 5, wherein the control and evaluation device is further designed such that it determines from the detection signal of the detection device as a received signal whether and/or when a document of value enters the acquisition region and/or whether and/or when a document of value is at least partially located within the acquisition region.

7. The sensor device according to claim 1, which further acts as a light barrier or a receiver of the optical scanner with at least one detection element not belonging to the detection device for converting the radiation of the radiation source into an electrical reception signal, which detection element does not receive the detection radiation, and wherein the coupling of the reference radiation into the optical path of the detection radiation takes place depending on the position of the value document relative to the acquisition area.

8. The sensor device according to claim 1, which further acts as a light barrier or a receiver of the optical scanner with at least one detection element not belonging to the detection device for converting the reference radiation into an electrical reception signal, which detection element does not receive the detection radiation, and wherein the coupling of the reference radiation into the optical path of the detection radiation takes place depending on the position of the document of value relative to the acquisition area.

9. The sensor device according to claim 1, wherein at least a part of the detection device acts as a light barrier or a receiver of the optical scanner, and wherein the coupling of the reference radiation into the detection radiation optical path takes place depending on the position of the value document relative to the acquisition area.

10. Sensor device according to claim 9, wherein the control and evaluation device is further designed such that it determines from the detection signal of the detection device as a received signal whether and/or when a document of value enters the acquisition region and/or whether and/or when a document of value is at least partially located within the acquisition region.

11. The sensor device according to one of claims 1 to 10, wherein the reference radiation device is designed such that the bandwidth of the reference radiation spectrum in the spectral detection region is less than 5 nm.

12. The sensor device according to one of claims 1 to 10, wherein the reference radiation device has a fluorescent sample which is excited by optical radiation of a radiation source to output reference radiation in the form of fluorescent radiation.

13. The sensor device according to one of the preceding claims 1-10, wherein the radiation source serves as a source of reference radiation and comprises a surface emitting laser diode, a DFR laser diode or a DBR laser diode.

14. The sensor device according to one of claims 1-10, wherein the radiation source serves as a source of reference radiation and comprises a temperature-stabilized edge-emitting laser diode or an edge-emitting laser diode with a wavelength-selective optical resonator.

15. Sensor device according to one of claims 1 to 10, in which the control and evaluation device is further designed to determine a spectral characteristic of the reference radiation as a characteristic of the reference radiation and to use it in the examination or correction or evaluation.

16. Sensor device according to one of claims 1 to 10, in which the control and evaluation device is further designed to determine the intensity of the reference radiation as a characteristic of the reference radiation and to use it in the examination or correction or evaluation.

17. Sensor device according to one of claims 1 to 10, having at least one temperature sensor connected to the control and evaluation device via a signal connection for detecting the temperature of at least one part of the detection device and/or of at least one part of the reference radiation device and/or of a temperature compensation element connected to the detection device and/or the reference radiation device, and wherein the control and evaluation device is further designed to use the detected temperature also during the checking or correction or evaluation.

18. Sensor device according to one of claims 1 to 10, having at least one temperature sensor connected to the control and evaluation device via a signal connection for recording the temperature of at least one part of the radiation source and/or of a temperature compensation element connected to the radiation source, and wherein the control and evaluation device is further designed to use the recorded temperature in the checking or correction or evaluation.

19. The sensor device according to one of claims 1 to 10, wherein the detection device is designed such that the spectral detection region has a bandwidth of less than 400 nm.

20. The sensor device according to one of claims 1 to 10, wherein the detection device has a position-resolved CMOS field, NMOS field or CCD field.

21. Sensor device according to one of claims 1 to 10, in which the detection device has an arrangement of individual detection elements whose signals are read independently of one another.

22. Sensor device according to one of claims 1 to 10, wherein the control and evaluation device is further designed to switch the reference radiation device to a stationary state and then to a running state again for at least one predefined period of time and/or depending on the detection signal of the detection device depending on the position or movement of the acquired value document.

23. Sensor device according to one of claims 1 to 10, wherein the control and evaluation device switches the illumination device on in an operating state after a predefined time interval after the entry of a value document into the acquisition region is recognized, in order to illuminate the value document in the acquisition region with optical illumination radiation in a predefined spectral illumination region and switches the illumination device on in a rest state.

24. Method for capturing the movement and/or position of a value document relative to a capture region of a sensor device for spectrally resolved capturing of optical detection radiation, which is emitted by a value document transported in a predefined transport direction through the capture region of the sensor device, wherein the sensor device comprises a detection device for spectrally resolved detection of the detection radiation in at least one predefined spectral detection region and for the provision of a detection signal which describes at least one characteristic of the detected detection radiation, wherein:

the value document is transported along a transport path in a predefined transport direction into an acquisition region of a sensor device,

generating optical radiation which is at least partially directed to the transport path of the value document such that it is suitable for detecting a movement and/or position of the value document relative to the detection region and which serves to provide reference radiation which is coupled into the detection radiation optical path of the detection device and has a spectrum with a narrow band lying within a predefined spectral detection region and/or has at least one spectrum with an edge lying within a predefined spectral detection region,

collecting reference radiation from the collection area to form a detection signal which characterizes the reference radiation and is used for checking and/or calibrating the detection device and/or providing correction data which are used when analyzing the detection signal characterizing at least one feature of the detection radiation emitted by the value document, and

optical radiation from the transport path or reference radiation from the acquisition area is acquired and used for acquiring the movement and/or position of the value document relative to the acquisition area or for determining whether and/or when the value document enters the acquisition area and/or whether and/or when the value document is at least partially located within the acquisition area.

25. Method according to claim 24, wherein for the acquisition of the movement and/or position of the document of value relative to the acquisition area, or for the determination of whether and/or when the document of value enters the acquisition area and/or whether and/or when the document of value is at least partially located within the acquisition area, a detection element not belonging to the detection device which does not receive detection radiation is used to convert the optical radiation or the reference radiation into an electrical reception signal from which the position or movement of the document of value can be determined, and wherein from the reception signal it is determined whether and/or when the document of value enters the acquisition area and/or whether and/or when the document of value is at least partially located within the acquisition area.

26. Method according to claim 24, wherein for detecting a movement and/or a position of the document of value relative to the acquisition area it is determined from a detection signal of a detection device which characterizes the reference radiation whether and/or when the document of value enters the acquisition area and/or whether and/or when the document of value is at least partially located within the acquisition area.

27. The method according to claim 24, wherein the reference radiation is at least partially coupled into the detection radiation optical path depending on the position of the document of value relative to the acquisition area.

28. Method according to claim 24, wherein for acquiring a movement and/or position of the value document relative to the acquisition area, or to determine whether and/or when the document of value enters the acquisition area and/or whether and/or when the document of value is at least partially located within the acquisition area, a detection element not belonging to the detection device which does not receive detection radiation is used to convert the optical radiation or the reference radiation into an electrical reception signal from which the position or the movement of the document of value can be determined, and wherein it is determined from the received signals whether and/or when the value document enters the acquisition area and/or whether and/or when the value document is at least partially located within the acquisition area, and wherein the reference radiation is at least partially coupled into the detection radiation optical path depending on the position of the value document relative to the acquisition region.

29. Method according to claim 24, wherein for detecting a movement and/or a position of the document of value relative to the acquisition region it is determined from a detection signal of a detection device which characterizes the reference radiation whether and/or when the document of value enters the acquisition region and/or whether and/or when the document of value is at least partially located within the acquisition region, and wherein the reference radiation is at least partially coupled into the detection radiation optical path depending on the position of the document of value relative to the acquisition region.

30. The method according to one of claims 24 to 29, wherein reference radiation is used, the bandwidth in the spectrum of which has a width of less than 5nm in the spectral detection region.

31. A method according to one of claims 24 to 29, wherein the reference radiation is generated by at least one surface emitting laser diode or at least one DFR laser diode or at least one DBR laser diode.

32. The method according to one of claims 24 to 29, wherein the reference radiation is generated by a temperature-stabilized edge-emitting laser diode or an edge-emitting laser diode with a wavelength-selective optical resonator.

33. The method according to one of claims 24 to 29, wherein spectral characteristics of the reference radiation are determined as characteristics of the reference radiation and used in the examination or correction or determination of the data for analysis.

34. Method according to one of claims 24 to 29, wherein the intensity of the reference radiation is determined as a characteristic of the reference radiation and used in the examination or correction or determination of the data for analysis.

35. Method according to one of claims 24 to 29, wherein the temperature of at least one part of the detection device and/or of at least one part of a reference radiation device for generating the reference radiation and/or of a temperature compensation element connected to the detection device and/or the reference radiation device is acquired and used when checking or correcting or determining the data for analysis.

36. Method according to one of claims 24 to 29, wherein the temperature of at least one part of the illumination device for illuminating the acquisition area and/or the temperature of a temperature compensation element connected to the illumination device is acquired and used in the verification or correction or determination of the data for analysis.

37. The method according to one of claims 24 to 29, wherein a detection device whose spectral detection area has a bandwidth of less than 400nm is used as detection device.

38. The method according to one of claims 24 to 29, wherein for detecting spectral components of the detection radiation and of the reference radiation coupled into the optical path of the detection radiation, a spatially resolved CMOS field, NMOS field or CCD field is used.

39. Method according to one of claims 24 to 29, wherein an arrangement of single detection elements is used for detecting the detection radiation and the reference radiation, the signals of the detection elements being read independently of one another.

40. Method according to one of claims 24 to 29, wherein the detection signals are controlled such that the detection of a movement and/or a position of the value document relative to the acquisition region takes place before and/or after the determination of the at least one characteristic of the reference radiation.

41. Method according to one of claims 24 to 29, wherein the intensity of the reference radiation is switched off or reduced and then switched on or increased again for at least one predetermined period of time depending on the position or movement of the acquired value document and/or depending on the detection signal.

42. Method according to one of claims 24 to 29, wherein, after a predefined time interval after the entry of a value document into the acquisition area is recognized, for illuminating the value document in the acquisition area, optical illumination radiation with a predefined minimum intensity in a predefined spectral illumination area is generated and radiated into the acquisition area, and the optical illumination radiation is switched off or its intensity is reduced.

43. The sensor device according to any one of claims 1 to 10, wherein the detection device emits a detection signal which describes at least one spectral feature of the detected detection radiation.

44. The sensor device according to one of claims 1 to 10, wherein at least one reference radiation device emits optical reference radiation having a spectrum with at least one narrow band lying within a predefined spectral detection range.

45. A sensor device according to claim 13, wherein no focusing optical element is provided in the radiation optical path after the surface emitting laser diode or DFR laser diode or DBR laser diode until the detection device.

46. The sensor device according to claim 23, wherein the control and evaluation device switches the value document to a stationary state when it leaves the collecting region.

47. A method according to any one of claims 24 to 29, wherein the detection means emits a detection signal describing at least one spectral feature of the detected detection radiation.

48. A method according to claim 31, wherein no focusing optical element is provided in the radiation optical path after the surface emitting laser diode or DFR laser diode or DBR laser diode until the detection means.

49. The method according to claim 42, wherein the optical illumination radiation is switched off or its intensity is reduced when the value document leaves the acquisition area.