EP2490185A2 - Device and method for optical examination of valuable documents - Google Patents

Abstract

The device has an illumination unit for illuminating a value document (12) in a part of a detection area, which contains a surface emitting laser diode. A control device is provided for controlling the laser diode, and a detection device is provided for detecting optical radiation out of a part of the detection area. The illumination unit contains another surface emitting laser diode for generating a predetermined light pattern in the detection area, and the control device is formed for controlling the other laser diode. An independent claim is also included for a method for optical examination of a value document in a detection area, involves illuminating the value document by an illumination unit.

Description

The present invention relates to an apparatus and a method for the optical examination of value documents.

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

Value documents are often visually examined to recognize their type and / or condition and / or to check for authenticity. In principle, the ambient light could be used for the examination, but such investigations are subject to excessive errors due to the fluctuations in the properties of the ambient light.

For investigation purposes, therefore, devices are used which comprise an illumination device for illuminating at least part of a section of a value document given optical radiation of predetermined properties by a detection region of the device and a detection device for detecting optical radiation illuminated from the detection region, in particular one of the illumination device Value document, comes, owns.

Although light sources such as halogen lamps can be used for illumination, they consume a lot of power compared to the radiation power emitted in a desired spectral range and therefore require adequate cooling. Next, they have the disadvantage that they do not have a very long life. In addition, these light sources have a significant amount of space.

The present invention is therefore an object of the invention to provide a device for the optical examination of documents of value, which allows a good lighting of a value document to be examined in a compact design, and to provide a corresponding method.

The object is achieved by a device for optically examining at least one value document in a detection range of the device, having an illumination device for illuminating the value document in at least a part of the detection region which has at least one surface emitting laser diode, a control device for driving the laser diode, and a detection device for detecting optical radiation from at least part of the detection area.

The object is further achieved by a method for the optical examination of a value document in a detection area, in which the value document is illuminated with at least one surface-emitting laser diode.

In the method, it is preferable to detect optical radiation from at least a part of the detection area which occurs by illuminating the value document. This can be, in particular, luminescence radiation excited in the value document, from the value document act back or passed through this optical radiation.

The detection device may accordingly be arranged relative to the illumination device and the detection region, in particular, such that their radiation entry is on the same side of the document of value from which it is illuminated, or on the opposite side. This means that the detection device can be arranged so that a study with incident or transmitted light or in reflection or transmission is possible.

In principle, the examination can be carried out if the document of value rests relative to the examination device and in particular the illumination device. In particular, when used in a value-document processing device in which value documents are examined automatically one after the other, however, the value document can also be moved during the illumination. The invention therefore also relates to a device for processing value documents, also referred to below as a value-document processing device, comprising an inspection device according to the invention and a transport device for moving a value document through the capture region at a predetermined transport speed. The transport speed can be predetermined in particular depending on the properties of the examination device or the transport device. In a sequential detection, an image of the portion of the value document moved through the detection area can thus be obtained.

The invention is completely different from the conventional types of lighting. So it is conceivable, for lighting instead of halogen lamps Conventional edge-emitting laser diodes (so-called "edge emitting laser diodes") to use, but radiate this optical radiation with a very inhomogeneous and not simply symmetrical intensity distribution. This may affect the examination of the value document.

According to the invention, a surface emitting laser diode is used for illumination. In the context of the present invention, a surface-emitting laser diode is more particularly understood to be a vertical surface emitting laser diode or, in particular, a semiconductor component referred to as vertical cavity surface emitting laser (VCSEL) whose laser resonator can be coupled out in the radiation from the laser resonator with its outcoupling direction is aligned at least approximately orthogonal to the surface of the device or chip. In particular, the laser resonator of such surface-emitting laser diodes can have reflection devices, for example reflection layers or layer systems, running at least approximately parallel to the surface.

Surprisingly, the use of such surface-emitting laser diodes offers several advantages for use in a device for examining value documents, also referred to below as the examination device.

Further, these can be made with large exit windows compared to edge emitting laser diodes, so that the emitted beam is little or not affected by diffraction at the edges.

In addition, surface-emitting laser diodes have a rotational profile which is rotationally symmetrical to a good approximation, resulting in beam shaping is made much easier with simple optical elements compared to edge emitting laser diodes.

Further, in surface emitting laser diodes, the emission wavelength range is more determined by the laser resonator than in edge emitting laser diodes. This allows narrower emission wavelength ranges and leads to a higher thermal stability of the emission wavelength range.

Preferably, the half-width (FWHM) of the emission spectrum is less than 1 nm.

Also, the spatial coherence of the emitted radiation is less than with edge-emitting laser diodes, so that speckle patterns can be largely or completely avoided on a document of value illuminated by the laser diode.

Due to the favorable beam shape of the surface emitting laser diodes they can be advantageously combined with each other for illumination purposes, so that in the method in addition to the laser diode at least one further surface emitting laser diode is used for illumination. It is therefore preferred in the examination device that the illumination device for generating a predetermined illumination pattern in the detection area has at least one further surface emitting laser diode and the control device is designed to control the further laser diode.

In this case, it is particularly preferred that the laser diodes are formed in a device or chip. Such a training is only for surface emitting Laser diodes easily possible and has the advantage that the production of a large array of laser diodes can be done easily. Another advantage is the fact that when assembling the inspection device only one component needs to be handled as a radiation source, which significantly simplifies the production.

More preferably, more than 50 laser diodes are arranged on a component.

The control of the laser diodes by means of the control device can be done in different ways. In the simplest variant, all the laser diodes of the illumination device are driven together, so that the illumination pattern available in the detection range is essentially determined by the number and arrangement of the laser diodes.

According to another embodiment, the illumination device has at least two groups of surface-emitting laser diodes, which comprise the aforementioned surface-emitting laser diodes, and the laser diodes of one group can be controlled independently of those of the other group. The control device is designed to control the one group of laser diodes separately from the control of the other groups of laser diodes. In the method, the document of value may then be illuminated with at least two groups of surface emitting laser diodes containing the laser diode, the laser diodes of one group being driven separately from those of the other group. In particular, a temporal and spatial variation of the illumination pattern is possible by controlling the groups, which offers the advantage of greater variability of the illumination. Under a separate or independent control or drivability is understood here that the laser diodes allow such control. Furthermore, the control device must be able to control the groups independently, wherein, of course, for example by programming the control device, a coupling of the control of the two groups of laser diodes can be done.

According to a further embodiment, the laser diodes can be controlled individually in the examination device and the control device is designed to control the laser diodes individually. If further surface-emitting laser diodes are used in the method for illuminating the value document, the laser diodes can then be activated individually. In particular, the control can take place independently or separately in the above-mentioned sense. The possibility of individual control of laser diodes on a chip is another advantage of surface emitting laser diodes.

The arrangement of the laser diodes and their driving the illumination pattern can be largely determined in its form, if only a simple illumination optics, i. In particular, an illumination optical system with at least approximately one, optionally folded by deflecting optical axis in the beam path rotationally symmetrical optical components such as lenses, is used. The use of only such an illumination optics simplifies and reduces the cost of manufacturing the illumination device.

An illumination device with a plurality of surface emitting laser diodes, preferably formed in a chip or component, can advantageously be used to generate a planar illumination pattern due to the shape of the beam profile of the laser diodes. For this the examination device is preferably designed to illuminate a predetermined area with an illumination pattern whose location-dependent intensity variation over the area illuminated by the laser diodes is less than 20% of the maximum intensity of the illumination pattern. In the method, the laser diodes can be controlled so that the laser diodes a predetermined area of the document of value is illuminated with a lighting pattern whose location-dependent intensity variation over the area is less than 20% of the maximum intensity of the illumination pattern. Such illumination is particularly homogeneous and thus facilitates a reliable detection of features. Preferably, the predetermined area has a content greater than 0.5 mm ² .

In principle, this homogeneity can be achieved by using suitable optical components or homogenizing devices in the examination device. Preferably, however, the surface emitting laser diodes are arranged relative to one another to illuminate a given area with an illumination pattern such that the illumination pattern generated therewith has a location-dependent intensity variation across the area less than 20% of the maximum intensity of the illumination pattern. As a result, the use of special optical components and in particular those of homogenizing devices such as lenses, diffractive optical elements or optical fibers, which reduce the intensity of the emitted optical radiation can be avoided. Therefore, the examination device particularly preferably has no homogenization elements such as, for example, scattering discs, light guides or microlens arrangements for homogenization.

The center distance of next adjacent surface emitting laser diodes of the illumination device is for this purpose preferably less than 150 microns

According to a first variant, the laser diodes can be arranged in matrix form in the examination device. In particular, they can be arranged on the grid points of a rectangular or square grid. This allows a particularly simple production of a laser diode array on a chip, in particular, since with a Einzelansteuerbarkeit the laser diodes, the corresponding signal connections can be easily designed. In addition, can be done with this arrangement a particularly simple control.

In a second variant of the examination device, the laser diodes are arranged on the points of a hexagonal dot grid. This arrangement has the advantage that achieved in a simple manner, a particularly dense arrangement of the laser diodes and thus a particularly homogeneous illumination pattern is made possible.

As already explained, the illumination pattern in the detection area or on the value document, at least in its shape, can essentially be determined by the arrangement of the emitting laser diodes. In the examination device, therefore, the control device is preferably designed to control only a part of the laser diodes for emitting optical radiation in order to generate a predetermined illumination pattern. Accordingly, in the method, preferably, the laser diodes are driven to emit optical radiation, so that a predetermined illumination pattern is generated. This embodiment has the advantage that, depending on the training to a change of the illumination pattern only a change of the control device is necessary. If this is programmable, which is preferred, even only the program needs to be changed.

Higher flexibility is achieved if, in a preferred embodiment of the inspection device, the control device is designed to control the laser diodes in response to a signal or data stored in the control device in such a way that the same illumination pattern depends on the signal or data in the detection region different predetermined locations can be generated. In the method, the laser diodes can then be driven in response to a signal or data such that, depending on the signal or data, the same illumination pattern can be generated at one of at least two different locations. The signal can be read in, for example, via an interface from an external data input device or transmitted by a device of the value-document processing device containing the examination device. The control of the laser diodes may in particular consist in that only a part of the laser diodes is switched on or off.

Thus, in a preferred embodiment of the inspection device, in particular the control device, the surface emitting laser diodes so drive that an extension of a detection range of the detection device in the transport direction is smaller than the extension of the illumination pattern in the transport direction and that the illumination pattern seen in the transport direction with respect to the detection area on as against the transport direction. In this case, the detection region is understood as meaning that section of the detection region from which, in particular, except for scattered radiation alone, the detection device can receive optical radiation for detection. A signal or data on the direction of transport may be provided to the controller in the ways indicated above, which performs the control of the laser diodes in response to the signal or the data. This can be achieved at the same time two things. First, by the greater extension of the illumination pattern in the transport direction in a study, in particular a Lumineszenzuntersuchung to a predetermined range of the value document, such as a track with feature substances, a larger amount of optical radiation, ie more energy, are blasted, so that the strength of the detection radiation can be increased. Secondly, the setting of the examination device, or more precisely the position of the illumination pattern relative to the detection area, can be set automatically when installed in the value-document processing device as a function of the transport device by transmitting corresponding signals to the control device, for example from a drive of the transport device or another device of the value-document processing device or entered manually via an interface. The examination device can therefore be designed and used as an easily configurable module.

In the embodiment just described, the drive can be switched between two or more lighting pattern layers in particular.

Alternatively or in combination, in the examination device, the control device may be designed to control the laser diodes so that an illumination pattern which changes over time during the illumination is generated in the detection region. In the process it is then it is preferred that the laser diodes are driven to produce a lighting pattern that changes with time during illumination. The temporal change can be predetermined in particular, for example, by a corresponding training and / or programming of the control device.

The illumination pattern can be changed in any way, in particular, the shape of the illumination pattern can be changed. However, it is preferred for many applications that the laser diodes are driven so that a predetermined illumination pattern is moved in a given direction at a predetermined speed. In the examination device, the control device is then designed to control the laser diodes so that a predetermined illumination pattern is moved in a predetermined direction at a predetermined speed. In this case, the movement only has to take place for a predefined period of time, for example, until the detection area has once been passed over by the illumination pattern. It is further assumed that the laser diodes are suitably arranged to produce the illumination pattern. This embodiment has a number of advantages, since it can be used for different purposes.

This embodiment makes it possible, in particular, to sequentially capture a one- or two-dimensional image. In particular, in this case, in the inspection apparatus, the detection means need only be formed so as to detect optical radiation coming from the detection area integrally or only one-dimensionally in a direction transverse to the moving direction of the illumination pattern. An integral detection is understood to mean a detection which is not spatially resolving at a given time. By successive lighting of different Places in the movement of the illumination pattern and a corresponding sequential detection such an image can be generated by the data or signals detected in each individual detection are assembled to the image.

In order to enable complete illumination that is as simple as possible to be generated, the examination device can be designed, in particular, to generate a rectangular, in particular line-shaped illumination pattern.

The examination device can be used in particular for detecting one- or two-dimensional barcodes by moving the illumination pattern.

In principle, the value document can rest on acquisition. However, for the quicker examination of a larger number of value documents with only one examination device, it is preferred in the method that the value document is moved during illumination in a predetermined transport direction and at a predetermined transport speed.

The speed of movement of the illumination pattern may differ in principle from the transport speed.

However, in the method, preferably, the value document is moved in a transport direction at a transport speed, the direction being the transport direction and the speed being the transport speed. In a particularly preferred embodiment of the processing device for processing value documents is then the Transport means for moving a value document formed by the detection area with a predetermined transport speed, and the control means is adapted to drive the laser diodes so that the illumination pattern is moved at the transport speed in the transport direction. This embodiment allows in a particularly advantageous manner, a tracking of a range of the examined value document, in particular an optical security feature, during the detection, so that an investigation is possible even at very high transport speeds.

In general, but in particular also in conjunction with the last-described embodiment, it is possible for the examination device that the control device is designed to generate a lighting pattern in a predetermined part of the detection area as a function of position signals of a position detection device. In the method, it is accordingly preferred that the laser diodes are driven in such a way that a lighting pattern is generated in a predetermined part of the detection area as a function of position signals of a position detection device. This embodiment has the advantage that by means of a device for determining the position of a value document or the position of a feature to be examined, the position, in particular relative to the examination device, reproducing position signal can be generated and that in response to this position signal exactly this feature can be illuminated and examined. As a result, the amount of data resulting from an examination of the entire value document can be greatly reduced, so that an examination can be carried out more quickly and an evaluation device for the evaluation of the detection results can be constructed more simply. Particularly in the case that the detection device for the spatially resolved detection of optical radiation is formed in at least one predetermined spectral range, a significant data reduction and an increase in the data processing speed can be achieved in pursuit of the feature.

As an alternative to or in combination with the previously described embodiments, the detection device can be designed to spatially resolve optical radiation in at least one predetermined spectral range and the control device can be designed to control the laser diodes so that a variation of the sensitivity of the optical detection device is achieved Radiation in the spectral range as a function of location is at least partially compensated. In the method, it is correspondingly preferred that the laser diodes are controlled so that a variation of a sensitivity of a detection device for spatially resolved detection of optical radiation in at least one predetermined spectral range as a function of location is at least partially compensated. In this way, even after a long time, a local adjustment of the illuminance to the sensitivity of the detection device, so that a permanent optical examination is possible permanently.

In the context of the invention, the laser diodes can be operated as continuously lit or pulsed radiation sources, for which purpose the control device is accordingly designed.

Fig. 1

eine schematische Darstellung einer Wertdokumentbearbeitungsvorrichtung nach einer ersten bevorzugten Ausführungsform;

Fig. 2

eine schematische Darstellung einer Untersuchungsvorrichtung der Wertdokumentbearbeitungsvorrichtung in Fig.1,

Fig. 3

eine schematische Draufsicht auf eine kantenemittierende Laserdiode,

Fig. 4

eine schematische Darstellung eines Strahlprofils der kantenemittierenden Laserdiode in Fig. 3 in Form eines Konturdiagramms

Fig. 5

eine schematische seitlichen Schnittansicht einer oberflächenemittierenden Laserdiode,

Fig. 6

eine schematische Darstellung eines Strahlprofils der oberflächenemittierenden Laserdiode in Fig. 5 in Form eines Konturdiagramms,

Fig. 7

eine schematische Draufsicht auf einen Chip der Untersuchungsvorrichtung in Fig. 2 mit einer matrixförmigen Anordnung von oberflächenemittierenden Laserdioden,

Fig. 8

eine seitliche Ansicht und eine Draufsicht für zwei mögliche Beleuchtungen durch Ansteuerungen der Laserdioden in Fig. 7,

Fig. 9

eine schematische Darstellung einer Wertdokumentbearbeitungsvorrichtung nach einer zweiten bevorzugten Ausführungsform

Fig. 10

eine schematische Darstellung einer zeitlichen Entwicklung einer Beleuchtung eines in der Wertdokumentbearbeitungsvorrichtung in Fig. 9 transportierten Wertdokuments, bei der das Beleuchtungsmuster dem Wertdokument nachgeführt wird, in einer seitlichen Ansicht und einer Draufsicht,

Fig. 11

eine schematische Darstellung einer zeitlichen Entwicklung einer Beleuchtung eines ruhenden Wertdokuments, bei der das Beleuchtungsmuster über das Wertdokument geführt wird, in einer seitlichen Ansicht und einer Draufsicht,

Fig. 12

eine schematische Darstellung eines Teils einer Detektionseinrichtung einer Untersuchungsvorrichtung nach einer weiteren Ausführungsform der Erfindung, und

Fig. 13

eine schematische Draufsicht auf einen Chip der Untersuchungsvorrichtung in Fig. 2 mit einer Anordnung von oberflächenemittierenden Laserdioden auf Gitterpunkten eines hexagonalen Punktgitters.

The invention will be explained in more detail below by way of example with reference to the drawings. Show it:

Fig. 1

a schematic representation of a value-document processing apparatus according to a first preferred embodiment;

Fig. 2

a schematic representation of an inspection device of the value-document processing device in Fig.1 .

Fig. 3

a schematic plan view of an edge emitting laser diode,

Fig. 4

a schematic representation of a beam profile of the edge-emitting laser diode in Fig. 3 in the form of a contour diagram

Fig. 5

a schematic side sectional view of a surface emitting laser diode,

Fig. 6

a schematic representation of a beam profile of the surface emitting laser diode in Fig. 5 in the form of a contour diagram,

Fig. 7

a schematic plan view of a chip of the assay device in Fig. 2 with a matrix-like arrangement of surface-emitting laser diodes,

Fig. 8

a side view and a plan view of two possible illumination by driving the laser diodes in Fig. 7 .

Fig. 9

a schematic representation of a value-document processing device according to a second preferred embodiment

Fig. 10

a schematic representation of a temporal evolution of a lighting one in the value-document processing device in Fig. 9 transported value document, in which the lighting pattern the value document is tracked, in a side view and a top view,

Fig. 11

2 is a schematic representation of a temporal development of a lighting of a static value document in which the illumination pattern is passed over the value document, in a lateral view and a plan view,

Fig. 12

a schematic representation of a portion of a detection device of an inspection device according to another embodiment of the invention, and

Fig. 13

a schematic plan view of a chip of the assay device in Fig. 2 with an array of surface emitting laser diodes on grid points of a hexagonal dot grid.

A value-document processing device 10 in FIG Fig.1 , which comprises a device for optically examining value documents 12, in the example of banknotes, has a feed pocket 14 for input of value documents 12 to be processed, a singulator 16, which can access value documents 12 in the input pocket 14, a transport device 18 a switch 20, and along a given by the transport means 18 transport path 22 arranged in front of the switch 20 device 24 for the examination of documents of value, and after the switch 20, a first output tray 26 for true recognized value documents and a second output tray 28 for as not genuine recognized value documents. A central control and evaluation device 30 is connected at least to the examination device 24 and the switch 20 via signal connections and serves to control the examination device 24, the Evaluation of test signals of the examination device 24 and for controlling at least the switch 20 as a function of the result of the evaluation of the test signals.

The examination device 24 in conjunction with the control and evaluation device 30 serves to detect optical properties of the value documents 12 and to form test signals representing these properties.

During the advance transport of a value document 12 at a predetermined transport speed in a transport direction T predetermined by the transport path 22, the inspection devices 24 detect optical property values of the value document, wherein the corresponding test signals are formed.

From the test signals of the examination device 24, the central control and evaluation device 30 determines in a test signal evaluation, whether the value document is recognized as true according to a predetermined authenticity criterion for the test signals or not.

For this purpose, the central control and evaluation device 30 has, in addition to corresponding interfaces for the sensors, a processor 32 and a memory 34 connected to the processor 32 in which at least one computer program with program code is stored, in the execution of which the processor 32 controls or controls the device ., the test signals evaluates and corresponding to the evaluation, the transport device 18 controls.

In particular, the central control and evaluation device 30, more precisely the processor 32 therein, can check an authenticity criterion, for example, for reference data for a value document to be regarded as authentic, which are predetermined and stored in the memory 34. Depending on the ascertained authenticity or non-authenticity, the central control and evaluation device 30, in particular the processor 32 therein, controls the transport device 18, more precisely the switch 20, so that the value document 12 can be deposited in the first output compartment 26 in accordance with its ascertained authenticity is transported for value documents recognized as genuine or in the second storage compartment 28 for value documents recognized as not genuine.

The examination device 24 is in Fig. 2 shown in more detail. It comprises a lighting device 36 for illuminating at least part of a planar detection area 38 in the transport path 22, into which value documents 12 to be examined via the transport path 22 pass, and a detection device 40. A control device 42 for controlling the illumination device 36 and an evaluation device 44 for evaluation of signals of the detection device 40 are combined in a programmed data processing device 46, which in this example a processor, not shown, and a memory, not shown, in which a program executable by the processor for controlling the illumination device 36 and for evaluating the signals of the detection device 40 is stored , includes. The control and the evaluation device 42 and 44 are connected via a signal connection to the central control and evaluation device 30.

The illumination device 36 has a semiconductor component or a semiconductor chip 48, in which a matrix-like arrangement of at least 50 surface emitting laser diodes 50 for emitting optical Radiation in a predetermined spectral range are formed (see. Fig. 7 The latter has a beam-focusing optics 54 along an illuminating beam path, a deflecting element 56 for deflecting the optical radiation emerging from the beam-converging optics into the detection area 38, and a focusing optics 58 for focusing the deflected illumination radiation as an illumination pattern 60 onto an illumination field 62 in the detection area 38.

The spectral range is given by the type of value documents to be examined, more precisely to these security features formed. In this example, luminescence properties of the value documents are to be investigated. For this purpose, the spectral range is chosen such that the excitation radiation for luminescence of a true value document lies within the spectral range. The deflection element 56 is deflecting for the excitation radiation, but transparent to the luminescence radiation to a good approximation, so that they can pass through the deflection element 56 without deflection.

From the detection range 38 or from a value document 12 outgoing optical radiation, ie detection radiation is imaged by the focusing optics 58 to infinity and passes through the deflector 56 without deflection in the detection device 40, which in the example detection optics 64, one by means of the detection optics 64 comprises illuminated spectrographic means 66, for example an imaging optical grating, and detection means 68 for detecting the intensity of spatially separated spectral components of the detection radiation produced by the spectrographic means 66. The detection elements 68 are for the transmission of detection signals, which reflect the intensity of the incident on them spectral components, to the evaluation device 44 connected to this via signal connections. The detection device 40 therefore detects the detection radiation is not spatially resolved, so that an integral detection of the detection radiation is given.

As in Fig. 7 illustrated in the semiconductor device 48 of the illumination device 36, the surface emitting laser diodes 50 in parallel rows and the rows orthogonal columns arranged, wherein the distance of the next adjacent laser diodes 110 microns is immediately before the respective laser diode.

For clear distinction from conventional edge emitting laser diodes is in Fig. 3 a schematic plan view of a semiconductor device 70 shown with an edge emitting laser diode. In the semiconductor device 70, a resonator 72 is formed parallel to the surface of the semiconductor device 70 or the wafer for the production of the semiconductor device, which is partially reflective at its edges 74 and 74 'along a low indexed lattice plane for the laser radiation to be generated and in the the laser active zone, ie a pn junction, the laser diode is located. The decoupled laser radiation is, as in Fig. 3 indicated, orthogonal to the edges 74 and 74 'and delivered parallel to the surface. The beam profile, ie the intensity distribution over a plane transverse to the beam direction is in Fig. 4 schematically represented as a contour diagram in which x and y are Cartesian coordinates in the plane and the lines represent lines of equal intensity. It is clear to recognize a saddle shape of the distribution, which is therefore not rotationally symmetric.

In Fig. 5 On the other hand, a surface-emitting laser diode 76 is shown schematically, in which a resonator 80 is arranged on a substrate 78, the is provided by parallel to the substrate 78 and the wafer surface 82 extending reflection structures or reflective layer structures 84, 84 ', for example in the form of interference layers. The laser radiation is now emitted orthogonal to the surface 82 of the wafer or the substrate 78. For the sake of simplicity, the electrodes and the distribution of the current-carrying layers are not explicitly shown.

In Fig. 6 is in one Fig. 4 corresponding representation, the beam profile of the output from the surface emitting laser diode laser beam. It is, to a good approximation, rotationally symmetrical about the beam direction and is therefore very well suited for further beam shaping with a simple illumination optical unit with spherical and planar optical elements, as in this exemplary embodiment.

The surface emitting laser diodes 50 are formed in the semiconductor device 48 and contacted so that they are individually controlled independently.

The number, arrangement and surface of the surface-emitting semiconductor diodes 50 and the illumination optics 52 are selected so that in the detection area 38 a continuous area illumination field with an area of at least 0.5 mm ² homogeneous, ie with an intensity variation with respect to the maximum intensity in the illumination area less than 20%, can be illuminated.

The control device 42 is used for the separate control of the laser diodes 50. In this embodiment, the examination device 24 is designed as a module for installation in a value-document processing device, which is constructed so that in principle the value documents 12 can be supplied from opposite directions.

In order to obtain the longest possible possible illumination of luminescent substances in a document of value to be examined, the control device 42 controls the laser diodes 50 in such a way that an illumination field 62 or an illumination pattern 60 is generated in the detection area 38, which continues to move counter to the transport direction T. a detection field 86 (see FIG. Fig. 8 The detection field 86 is defined by the fact that, with the exception of scattered radiation, only optical radiation can pass from the detection field 86 into the detection device 40. As a result, an area on the value document is exposed for a time to the illumination or excitation radiation which is longer than the time in which it lies in the detection field 86. As a result, an increased luminescence radiation can be achieved, which facilitates the detection of the luminescence.

The control device 42 is, here by appropriate programming, set up so that it controls a signal of the central control and evaluation device 30, which reproduces the transport direction T with respect to the position of the examination device 24, the laser diode 50 so that in dependence the transport direction T or the signal reproducing one of the two in Fig. 8 shown illumination pattern 60 and 61 is generated by the laser beams 88 in the detection area 38. These are shifted relative to the chip 48, so that the above-mentioned effect occurs. For this purpose, only a part of the laser diodes 50 is turned on, namely the in Fig. 8 left (a)) and right (b)) laser diodes, the others remain off. In the figure, the illumination optics 52 or their influence on the beam path is not shown for the sake of clarity. By "turned on" is understood that they are operated either continuously or pulsed.

A second embodiment in Fig. 9 differs from the first embodiment in that now along the transport path 22 upstream of an examination device 24 ', an image sensor 90 is arranged, which serves to capture images of added value documents and transmits the images via a video signal connection to a central control and evaluation device 30'. All other components are unchanged, so that the same reference numerals are used for them as in the first embodiment and the explanations to the first embodiment apply accordingly here.

The central control and evaluation device 30 'differs from the central control and evaluation device 30 in that it has an in Fig. 9 not shown interface for detecting the image data of the image sensor 90 and, in the example by a corresponding program module is adapted to determine from the image data, the position of the optical examination device 24 'to be examined in more detail range of the value document, such as a certain feature area and to the assay device 24 '. The image sensor 90 therefore represents a position detection device in conjunction with the central control and evaluation device 30 '.

The examination device 24 'differs from the examination device 24 of the first embodiment solely in that the control device is now changed relative to the control device 42. More specifically, the controller is configured to drive the laser diodes 50 differently than the controller 42. As in FIG Fig. 10 in a timeline a), b), c) schematically in one Fig. 8 shown corresponding manner, the control device controls the laser diodes 50 so that in front of each time in the transport direction T in the transport direction front laser diodes 92 on and in the transport direction rear laser diodes 94 are switched off. This is done so that the same illumination pattern 60 'or field 62', which is generated from laser beams 88 of the front laser diodes, is carried with the transport speed T in the direction of transport T directed to the selected area 98. As a result, only the selected region 98 is illuminated while being transported through the detection field 86. Thus, the generation of stray radiation or spurious radiation from other areas of the value document 12 can be effectively reduced.

In other embodiments, the image sensor 90 may also be replaced by other means, compared to the last embodiment, by means of which the position of certain features to be examined can be seen. For example, depending on the feature, a signal from an edge detector for detecting a leading edge of the document of value in the transport direction, for example a light barrier or an ultrasound sensor, in conjunction with the known transport speed and the known position of the feature on the document of value can also be used To generate position signal.

A further embodiment differs from the first exemplary embodiment in that, for examining a value document, the value document is now completely stopped and, after stopping in the detection area, a start signal is emitted to an examination device 24 ", to which the central control and evaluation device 30 is modified accordingly. The examination device 24 "differentiates itself from the examination device 24 of the first embodiment alone by the training or programming of the control and the evaluation device 42 and 44. For all other components, therefore, the same reference numerals are used as in the first embodiment and the explanations to these apply accordingly here ,

The control device is designed to control the laser diodes 50 such that they generate a lighting pattern that changes over time during the lighting. More specifically, the laser diodes are driven so that the same illumination pattern 60 "is moved over the document of value 12 at a constant speed in the example, as shown in FIG Fig. 10 in the representation corresponding Figure 11 in a time sequence a), b), c) is illustrated. At the same time, the pulsed control of the laser diodes, in synchronism with the pulses, the reflected detection radiation detected by the detection device 40 and the evaluation device 44 and stored according to the time sequence and thus the location on the value document in the evaluation device 44 or directly to the transmit central control and evaluation. This will get an image of the value document. The corresponding image data are transmitted, possibly after the intermediate storage in the evaluation device, in the central control and evaluation device 30 and further evaluated there.

The illumination pattern 60 "is, as in Fig. 11 illustrated, rectangular slot-shaped. Preferably, the illumination pattern 60 "is so narrow that it can serve as a" virtual "entrance slit for the detection device or the spectrographic device, which then no longer has to have an entrance slit.

Such an examination device can also be advantageously used for the detection of barcodes. In particular, in this case, the detection device then only needs to have one detection element, but no spectrographic device.

In another variant, instead of only one detection element, a row of detection elements may be provided in the detection device, by means of which areas in the detection or detection area can be detected spatially resolved along a line transversely to the movement direction of the illumination pattern. Such an examination device can also serve in particular for the detection of two-dimensional barcodes.

In a further embodiment, the examination device differs from the examination device of the first embodiment by another detection device 40 "'and another control and evaluation device.

The detection device 40 '"(cf. Fig. 12 ) now has a field 100 with a two-dimensional arrangement of detection elements 102 for the spatially resolved detection of optical radiation coming from the detection area 38 or the detection area 86 and an imaging optics 104 for focusing the infinite beam path after the focusing optics 58 onto the arrangement of detection elements 102 Detection elements 102 may have different sensitivities for optical radiation in the same spectral range, for example as a result of variations in production or due to different aging.

The control device 42 "is changed in relation to the control device 42 to that end, that is, it is configured to connect the laser diodes 50 in accordance with the Sensitivity of the detection elements 102 so controls that the differences in sensitivity are compensated. More specifically, this means that the laser diodes 50 are driven so that all the detection elements 102 output the same detection signals.

In this way, errors in the imaging optics can be compensated.

The evaluation device 44 "is designed to detect the detection signals of the detection elements 102.

In a particularly preferred embodiment, the control device is designed to detect the detection signals of the detection elements for a given control of the laser diodes by means of the evaluation device, and to automatically change the control of the laser diodes so that all detection elements emit the same detection signal.

This corresponds in a sense to a calibration of the examination device. Depending on the embodiment, this process can be carried out automatically at given intervals of the operating time of the examination device or whenever the examination device is switched on or off, for which purpose the control device can be designed accordingly, for example by appropriate programming.

Yet another embodiment differs from the first embodiment only in that the surface emitting laser diodes 50 are formed and contacted in the semiconductor device so that they are separately or independently controllable in at least two groups, in this embodiment, line by line. Corresponding the control device 42 is modified to control the groups, ie here the rows, separately from one another, wherein the same illumination pattern as in the first embodiment can be obtained.

Other embodiments differ from the previously described embodiments only by the arrangement of the laser diodes 50 in the semiconductor device 48 '. All other parts are unchanged. In the semiconductor device 48 ', the surface emitting laser diodes 50 are now (see. Figure 13 ) are arranged on the grid points of a hexagonal dot grid with a distance of nearest neighbors smaller than 120 μm, in the example 100 μm, whereby a further increased homogeneity of the illumination pattern can be achieved.

In still other embodiments, the illumination device does not have the deflection element 56, so that a rectilinear illumination beam path is achieved. The detection device is designed and arranged for the detection of optical radiation after transmission through the value document. It has its own optics corresponding to the focusing optics for imaging at least a portion of the value document from the side not illuminated by the illumination device.

In other exemplary embodiments, the illumination of the value document can also take place in angles deviating from 90 °, in which case the detection device may be designed and arranged accordingly.

Claims (23)

Apparatus for the optical examination of at least one value document (12) in a detection area (38) of the apparatus, comprising illumination means (36) for illuminating the value document (12) in at least a part of the detection area (38) comprising at least one surface-emitting laser diode (50; 76) and has at least one further surface emitting laser diode (50, 76) for generating a predetermined illumination pattern in the detection area,
a control device (42) for driving the laser diode (50; 76) and for driving the further laser diode (50; 76), and
a detection device (40; 40 "') for detecting optical radiation from at least part of the detection area (38),
wherein the illumination device (36) comprises at least two groups of surface emitting laser diodes (50; 76) comprising the laser diodes (50; 76), wherein the laser diodes (50; 76) are each controllable by one group independently of the other group, and the control device (42) is designed to drive the one group of laser diodes (50; 76) separately from the drive of the other groups of laser diodes (50; 76), and / or wherein the control device (42) is designed to only each to drive a portion of the laser diodes (50; 76) to emit optical radiation to produce a predetermined illumination pattern (60). Apparatus according to claim 1, wherein the laser diodes (50; 76) are formed in a device (48) or chip. Device according to one of the preceding claims, in which the laser diodes (50; 76) can be controlled individually and the control device (42) is designed to drive the laser diodes (50; 76) individually. Device according to one of the preceding claims, which is designed to illuminate a predetermined area with an illumination pattern (60) whose location-dependent intensity variation over the area illuminated by the laser diodes (50; 76) is less than 20% of the maximum intensity of the illumination pattern (60 ). Apparatus according to claim 4, wherein the predetermined area (62) has a content greater than 0.5 mm ² . Apparatus according to any one of the preceding claims, wherein the laser diodes (50; 76) are arranged in matrix form. Apparatus according to any one of claims 1 to 5, wherein the laser diodes (76) are disposed on the points of a hexagonal dot grid. Apparatus according to any one of the preceding claims, wherein the control means (42) is arranged to drive the laser diodes (50; 76) in response to a signal or data stored in the control means (42) so as to depend on the signal or signal Data in the detection area (38) the same illumination pattern (60) at different predetermined locations can be generated. Apparatus according to any one of the preceding claims, wherein the control means (42) is adapted to operate the laser diodes (50; 76) to cause a lighting pattern (60) changing over time in the detection area (38) to be generated. Apparatus according to any one of the preceding claims, wherein the control means (42) is arranged to drive the laser diodes (50; 76) to move a predetermined illumination pattern (60) in a predetermined direction at a predetermined speed. Device according to one of the preceding claims, which is designed to produce a rectangular, in particular line-shaped illumination pattern (60). Device according to one of the preceding claims, in which the detection device (40) integrally detects optical radiation coming from the detection area (38) or in which the detection device (40 '') is designed for spatially resolved detection of optical radiation in at least one predetermined spectral range, and in which the control device (42) is designed to control the laser diodes (50, 76) in such a way that a variation of a sensitivity of the detection device (40 "') for the optical radiation in the spectral range as a function of location is at least partially compensated. Device according to one of the preceding claims, in which the control device (42) is designed to generate a lighting pattern (60) in a predetermined part of the detection area (38) as a function of position signals of a position detection device (30 ', 90). Apparatus for processing value documents (12) having an examination device (24) according to one of the preceding claims, and a transport device (18) for moving a value document (12) through the detection area (38) at a predetermined speed, wherein preferably the transport device (18 ) for moving a value document (12) through the detection area (38) at a predetermined transport speed, the control device (42) is designed to control the laser diodes (50, 76) so that the illumination pattern (60) is moved in the transport direction at the transport speed , Method for optical examination of a value document (12) in a detection area (38), in which the value document (12) is illuminated with at least one surface emitting laser diode (50; 76) and further surface emitting laser diodes (50; 76) and wherein the value document ( 12) is illuminated with at least two groups of surface emitting laser diodes (50; 76) containing the laser diodes (50; 76), the laser diodes (50; 76) of one group being driven separately from those of the other group and / or at in that the laser diodes (50; 76) are driven to emit optical radiation so that a predetermined illumination pattern (60; 61) is produced. The method of claim 15, wherein the laser diodes (50; 76) are individually driven. Method according to one of Claims 15 or 16, in which the laser diodes (50; 76) are controlled in such a way that with the laser diodes (50; 76) a predetermined area of the value document having a lighting pattern (60; 61) whose location-dependent intensity variation across the area is less than 20% of the maximum intensity of the illumination pattern. A method according to any of claims 15 to 17, wherein the laser diodes (50; 76) are driven in response to a signal or data such that, depending on the signal or data, the same illumination pattern (60; 61) is applied to one of at least two can be generated in different places. A method according to any one of claims 15 to 18, wherein the laser diodes (50; 76) are driven to produce a lighting pattern (60 ') changing over time during illumination. A method according to any one of claims 15 to 19, wherein the laser diodes (50; 76) are driven so that a predetermined illumination pattern (60 ') is moved in a predetermined direction at a predetermined speed. A method according to claim 20, wherein the document of value (12) is moved during the illumination in a predetermined transport direction and at a predetermined transport speed, and in which the value document (12) is preferably moved in a transport direction at a transport speed and the direction is the Transport direction and the speed is the transport speed. A method according to any of claims 15 to 21, wherein the laser diodes (50; 76) are driven so that a variation in sensitivity a detection device (40 "') for the positionally correct detection of optical radiation in at least one predetermined spectral range as a function of location is at least partially compensated. Method according to one of Claims 15 to 22, in which the laser diodes (50; 76) are controlled in such a way that, as a function of position signals of a position detection device (30 '; 90), a lighting pattern (60') is generated in a predetermined part of the detection area (38). is produced.

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