DE10234431A1 - Device and method for processing documents of value - Google Patents

Abstract

The invention relates to a device and a method for processing documents of value, with an examination of a security element of the document of value, in particular an examination of the type and / or authenticity and / or fitness of a security element with an optically variable effect. DOLLAR A Because a mechanical detection of the light emanating from an illuminated area of the security element in one or more different directions, which do not correspond to the direction of reflection, is carried out in combination with an image acquisition of the illuminated area, such security elements can be checked particularly simply and reliably ,

Description

The invention relates to a device and a method for processing value documents, with a test equipment for testing a security element of the value document, in particular for checking the Type and / or authenticity and / or fitness of security elements, which show an optically variable effect where the security element different visuals from different viewing angles impressions generated.

Such security elements can be a component of value documents, such as banknotes, credit cards, Personal documents or product protection labels to identify the Authenticity of different goods. The present is indeed Invention not limited to In the following, however, the main focus is on the testing of security elements received with optically variable effect on banknotes.

For one, banknotes are considered such security elements diffractive structures, such as Holograms, especially surface holograms, or kinegrams used.

However, it is also possible to use all other optically variable elements which give a different visual impression at least at two different viewing angles. For example, optically variable inks are also used as printing ink, optically variable thin-film films or Iriodin imprints or polymeric liquid crystal colors, which convey a different color impression at different viewing angles. This is also known as the color change effect. So-called “latent images” can also be used. Such security elements in EP 0 863 815 A1 and EP 0 827 457 A1 described.

For machine testing of Banknotes with such security elements exist in different ways Test methods. WO 98/55963 describes e.g. a method of detecting Diffraction patterns on banknotes. The banknote to be checked extensive with parallel light irradiated vertically. The entire illuminated area accordingly of the different diffraction directions is point-based separate sensors or alternatively to different sensor areas of a single sensor. By comparing the measurement signals with specified reference values according to the expected values Diffraction symptoms are due to the presence of a special diffraction structure closed.

This known system has the disadvantage that due to the large-area lighting and subsequent punctate Focusing the illuminated areas, the position or shape of the diffraction structures cannot be determined exactly on the banknote.

Based on this, it is the task of the present invention, an apparatus and a method for machine testing to provide value documents that are simple and secure machine testing, in particular of security elements with an optically variable effect allow.

This task is accomplished by the device Claim 1 and the method according to claim 23 solved. The dependent Expectations describe preferred configurations.

One aspect of the present invention is based on the test, especially examining the Type and / or authenticity and / or fitness for purpose of a security element of a document of value with optically variable effect, through machine Detection of an illuminated area of the security element light coming out in one or more different directions, which do not correspond to the direction of reflection, in combination with an image capture of the illuminated area.

It should be noted that under the direction of reflection in the sense of the present invention a non-diffuse and directed reflection is understood, at which the angle of incidence is the angle of reflection of the light radiation equivalent. Image capture is also understood to be one Illuminated area of the banknotes on a sensor surface Map sensors; to at least create a two-dimensional image to win an area of the banknote which e.g. with itself known methods of pattern recognition automatically with predetermined Reference images, e.g. according to real banknotes can be.

This procedure allows simple and reliable not only the exact position and shape by means of image acquisition, such as. the outline and displayed information on each individual security element to determine each banknote, but also by combination with the detection of light that is not in the direction of reflection from the one to be checked Banknote, also based on the presence e.g. of diffractive Close structures. Under the possibility The examination the type of security element is understood that between different security elements, e.g. of banknotes different Denomination, distinguished can be.

When checking for existence of security elements with optically variable color effects, e.g. banknotes with optically variable ink printed on can also by comparing in the non-reflection direction outgoing light with outgoing from any other direction Light, preferably by comparison with predetermined reference values accordingly e.g. real banknotes, on the presence of a suitable one directionality getting closed. For this, e.g. a color comparison or a comparison the signal strength be carried out with a certain color in the two measuring directions.

In contrast, according to WO 98/55963 only determined if at all any security elements with appropriate diffraction characteristics exist anywhere on the banknote. A closer look at in terms of the number, shape and distribution of the security elements in the illuminated area of the banknote is not possible.

According to a preferred embodiment of the The present invention uses separate image capture Sensor done. However, image capture is particularly preferred by at least one of the sensors that are not used for detecting the Direction of reflection from the banknote to be checked serve outgoing light. This has the advantage that the test device not only cheaper, but also more compact can.

It turned out to be a Series of influencing factors in The examination of security elements, in particular of those with optically variable Effect gives, the following example based on preferred embodiments to be discribed. Particular attention is paid to the examination of diffraction structures, such as. of holograms and / or kinegrams in a banknote paper can be applied or applied, received. For special features when testing security elements with color change effect is indicated separately.

Banknotes to be checked usually indicate dependent on of their denomination Security elements with optically variable effect on the different Have properties. So can they e.g. diffraction-specific in the diffraction pattern represent different information and / or in different Bend the diffraction direction or angle.

The directional dependence of the diffraction phenomena proves to be an essential property of banknotes verify with a high degree of certainty the existence of diffractive structures. So can by detecting light that is not in the direction of reflection starts from a directionally irradiated banknote, using sensors, which are arranged in the or the expected diffraction directions are a distinction to non-diffractive, fake Banknotes such as to photocopies, be done safely.

The diffraction angles are wavelength-dependent, so that it at least for lighting with multiple colors, in a given one Diffraction direction color-dependent Signals there. When using illuminating light or equivalent Sensor color filter of different wavelengths or wavelength ranges different diffraction characteristics (directions of diffraction, diffraction intensity in these directions), which in turn when assigned by assigned Sensors the authenticity of such security elements is particularly secure check to let. Will at least one sensor for detecting in a fixed predetermined solid angle range of light emanating from the banknote installed, can consequently by choosing or varying the lighting color be achieved for a particular Color for the one to be checked Diffraction structure is specific, with real banknotes a higher signal intensity than for others Colors is measured. As a result, it can also be safely between several different diffraction structures can be distinguished.

Unless banknotes are different denomination with the same lighting conditions, i.e. especially with lighting in the same direction and with the same wavelength, all diffraction in at least show a common direction, the detection of Diffraction light in just this one direction is enough to do with little Effort an examination also for different denominations with a simple sensor. For example, all current EURO banknotes show diffraction in a direction parallel to the short edge of the banknote. Therefore e.g. in this case already for testing a single sensor is sufficient, this parallel to the short Banknote edge detected outgoing light.

Another relevant size is the Amount of measurement signals of the sensors. If measurements are made in the direction of diffraction, the corresponding real banknotes the signals significantly larger than e.g. for photocopies that are only diffuse in the non-reflection direction sprinkle. To improve the measuring accuracy, in particular for better differentiation against only diffusely scattered light, should therefore, the intensity of the measurement signals is preferably normalized in comparison to the intensity of the illuminating light.

A criterion can also be derived from the signal strength for the manufacturing quality of newly manufactured and / or for gain the degree of wear of circulating banknotes. In the event of deviations from a predetermined threshold or acceptance range for example, the lack of manufacturing quality of the respective security elements getting closed. Furthermore are for those already in circulation Banknotes lower signal strengths given lighting and measuring conditions a sign of wear and tear, what can be used as a criterion for rejecting such banknotes can.

The polarization behavior of the security elements can also serve as an additional or alternative test criterion. It has been shown that when linearly polarized light is diffracted on security elements with an optically variable effect, the polarization is at least partially retained. This applies not only to diffraction phenomena, but also to reflections on security elements with a color change effect, such as on prints with Iriodin or optically variable inks, and even on intaglio profiles that show no optically variable effect. In contrast, this effect has with litter Not shown on the banknote paper itself and for offset printing elements. The light incident on such areas is reflected essentially diffusely. Only when there is a very large, almost grazing incidence is the light reflected in greater proportions, whereby the polarization is clearly retained. Therefore, in this case of a polarization test, illumination with a small angle to the perpendicular of the illuminated area is particularly advantageous. The angle of incidence should be at least less than 40 degrees, preferably less than 20 degrees, a vertical incidence of light in which the angle of incidence is zero is particularly preferred.

Furthermore, the determination is also the position and / or the outline of the banknote in relation to the test facility advantageous in order to i.e. the area in which measurements are made or the measurement signals are evaluated, in dependence of to restrict the position or the outline optionally also denomination-specific, whereby there is a data reduction and thus faster evaluation can.

Taking into account the aforementioned factors, the components of the test facility can preferably have one or more of the following properties:
In addition to coherent laser diodes, non-coherent light sources such as incandescent lamps, LEDs or fluorescent lamps can also be used for lighting. The lighting should have a defined divergence and direction so that the contrast against diffuse scatter from the banknote paper to be checked is large enough. However, a minimum aperture is necessary to compensate for changes in direction of the paper.

The spectrum of the light source can chosen differently become. For example, with white light be illuminated. This has the advantage that there is a wide band simultaneously of diffraction directions for different colors because the sine of the diffraction angle in is substantially proportional to the wavelength. By choosing sensors for different Colors and / or with changing color filters for the sensors and / or one Spectral analysis of the measurement signals can, e.g. even with constant lighting with white light, a color-selective analysis and thereby an acquisition and differentiation can also be performed safely between different diffraction structures. However, in this case the intensity of the scattered light is from the paper enlarged compared to monochromatic lighting.

Therefore you can alternatively use one or more individual colors or color areas are illuminated. In this case too, with lower interference signals due to diffuse light scattering, from the color information for the presence of diffraction and / or differences in diffraction characteristics can be inferred.

With variation of the illumination wavelength for example, a single sensor for testing different ones Diffraction structures are sufficient, which in itself when using only a single wavelength of illumination may not all in those detectable by the sensor Would bend solid angle range.

With single-color or white lighting the light is preferably emitted in a stationary manner at multicolored lighting is a time-division lighting from Advantage. Alternatively, in this case it can be multi-colored lighting also give several sensors arranged one behind the other or next to one another, each for another of the lighting colors are sensitive. It can be with a Sensor line e.g. For Adjacent pixels also have different color filters, respectively of individual lighting colors. So there is also one temporally stationary Lighting possible.

Particularly preferred configurations furthermore arise then when individual banknotes by means of a transport device be passed past or through a sensor for measurement. This usually happens in devices for sorting and / or counting or for depositing and / or Withdrawing banknotes.

In this case, the use of a or several separate line sensors, especially in combination with a line-shaped Lighting as very beneficial, taking the line sensors or the line-shaped Illumination in each case transverse, preferably perpendicular to the direction of transport should extend. This has the advantage that the test device by means of inexpensive Components can be constructed very compact.

The arrangement of the Sensors and thus the direction of observation through the banknote edges be given, optionally with an additional line sensor at 45 ° can come.

The line-shaped lighting, for example by using a line-shaped light source, i.e. a light source with a linear aperture diaphragm. As line sensors e.g. CCD line sensors are used. The term In particular, line sensors can mean that the sensor consists of a single Series of sensor fields, i.e. Pixels.

The length of the illuminated area of the banknote and the light-sensitive measuring surface at least one of the line sensors preferably corresponds approximately or is greater than or equal to the length the biggest too measuring security elements, particularly preferably it corresponds but at least the length the largest banknote, So that the entire banknote area can be scanned by the line sensor.

Preferably, a line sensor is also arranged close to the light source, such as the LED line, for detecting perpendicular to the trans outgoing light. This line sensor can optionally also be used for image acquisition of the illuminated area according to the invention.

According to another preferred embodiment is another line sensor to detect the in a certain Angular range in or against the outgoing light be arranged. Several such additional line sensors can be placed side by side be arranged, each of the further line sensors in each case to detect another direction, i.e. of another determined Angular range in or against the transport direction Light serves. This has the advantage that it can also record different ones Security elements, e.g. with different grid parameters diffraction structures that bend in different directions, simply possible is.

For examining holo- or kinegrams, the banknotes are preferably illuminated vertically and that in the expected directions of diffraction diagonally from the Illuminated banknote outgoing light through the aforementioned line sensors detected. With the same illuminance is that of a diffraction structure in its direction of diffraction first (or higher) order bent and grasped Radiation intensity greater than that of a non-diffractive structure, e.g. customary Paper or metal strips, diffusely reflected in such a direction becomes. In order to be able to measure this difference, there is a lighting control or a recording of the intensity the illuminating radiation as a reference for normalizing the measurement signals of the sensors is an advantage.

It should be noted that the use of line sensors, in particular in banknote processing devices is of particular advantage, but can alternatively or additionally also Cameras with two-dimensional image acquisition can be used.

For the exam of security elements with color changes when viewed in different Directions, e.g. of banknotes made with optically variable ink printed, it turns out not a vertical one, but one slope Lighting as particularly preferred. When using an LED line, the Azimuth of the radiation should be oriented perpendicular to the LED line. A lighting control or reference for standardizing the measurement signals is not absolutely necessary in this case.

Instead, it may be enough if for the sensors arranged in two different directions a color difference measurement is carried out to show the characteristic different To be able to measure color properties. So can preferably e.g. a sensor arranged in and a sensor against the oblique direction of illumination to be by comparison, e.g. a difference of the measuring signals of the two sensors for differences in the intensity of the colors close.

When lighting with several Colors become the signals recorded in parallel in all sensors for a value document according to the time multiplex parameters used Sorted separately according to lighting colors and evaluated separately. The sensors are preferably broadband in the visible spectral range, a color selection is not absolutely necessary.

In all the previously described embodiments, the illumination and / or detection of light emanating from the illuminated banknote light is preferably by means of self-focusing lenses, so-called SELFOC ^® lenses are performed. These are cylindrical optical elements made of a material that has a refractive index that decreases from the optical axis of the cylinder to its surface. By using such a lens, for example, a 1: 1 mapping of the area to be measured onto the sensor, which is independent and within certain limits of the distance from the bank note to the sensor, is achieved. Due to the usual unevenness of banknotes in circulation, this property is of great advantage in order to be able to compensate for position fluctuations in the image. Instead of SELFOC lenses, weakly telecentric lenses also prove to be advantageous. The SELFOC lenses can also be used to adjust the aperture angle of the illuminating light source.

Another idea of the present The invention consists in the use of prisms for beam deflection. In particular, Fresnel prisms have the advantage that the test device can be particularly compact. An almost symmetrical one To ensure beam path we the flat surface of the Fresnel prism preferably faces the security element his.

Yet another idea of the present The invention consists in illuminating an area of the security element by at least two light sources arranged at different angles of illumination. In contrast to the variants mentioned above, this Advantage that already a single common sensor may suffice to relate to that the angles of illumination in different diffraction or reflection angles Detect light emanating from the banknote using time division multiplexing to be able to. Since light sources are generally cheaper than corresponding sensors, and only the measurement signals of a single sensor must be evaluated, the test facility cost-effective getting produced.

According to a further alternative, at least two images of the illuminated area are generated by means of a symmetrical beam path , and detected by associated sensors, each of which corresponds to a different viewing angle. This can ensure that the images have the same image scale, or the same enlargement or reduction, and / or no or the same distortion.

This makes it easy to compare the signals corresponding to the two possible, for example, by simple difference formation

In particular, a single prism, in particular a Fresnel prism can be used to simultaneously the two figures according to different viewing angles two separate sensor areas to be able to map.

It should be emphasized that the individual characteristics of the dependent Expectations and / or the exemplary embodiments mentioned in the description in combination, also completely or at least partly independent from each other and from the subject of the main claims, advantageously used can be.

For example, the solutions described are at least two arranged at different lighting angles To use light sources, or polarization, in particular to check the direction of polarization also independently of advantage whether an image acquisition according to the invention is actually carried out.

Other advantages of the present Invention will become apparent from the reference to the accompanying drawings explained in more detail Embodiments.

The show

1 is a schematic perspective view of a banknote with a representation of the beam paths of the test device according to the 2 and 3 ;

2 a schematic view from above of part of a banknote processing device with a test device according to a first embodiment;

3 a sectional view of the device after 2 along line II;

4 a view accordingly 3 on part of a banknote processing device with a test device according to a second embodiment;

5 a view accordingly 3 on a part of a banknote processing device with a test device according to a third embodiment;

6 a view accordingly 3 on part of a banknote processing device with a test device according to a fourth embodiment;

7 a view accordingly 3 on part of a banknote processing device with a test device according to a fifth embodiment;

8th a view accordingly 3 on a part of a banknote processing device with a test device according to a sixth embodiment;

9 a view accordingly 3 on part of a banknote processing device with a test device according to a seventh embodiment; and

10 a view accordingly 3 on a part of a banknote processing device with a test device according to an eighth embodiment.

The with the test facilities according to the invention 2 banknotes to be checked 3 exemplarily as a security element 5 an embossed hologram 5 on. Like in the 1 is indicated, this hologram has 5 inter alia, the property that it bends light in the direction B at an angle α, as well as in the direction R2 at an angle β to the direction B in the case of perpendicular irradiation in the direction B, and in doing so represents different information in these directions. For example, when looking in the direction of R1, the number "50" and in the perpendicular direction R2 the character "EUR" can be clearly seen. Banknotes of different denominations have different diffraction properties. The number shown in the R1 direction can be selected, for example, according to the denomination. Typical angles α, β are 15 to 25 degrees at typical illumination wavelengths from 450 nm to approx. 900 nm.

The 2 and 3 show a first example of an associated test facility 2 , This is part of a banknote processing device 1 , which can be constructed in a manner known per se and is therefore not shown in detail. The banknotes to be checked 3 are by means of a transport device 4 , which includes, for example, a belt and / or roller transport, individually in the direction X with its transverse side at the test device 2 transported over.

The testing facility 2 can have further components for machine testing of, for example, optical, electrical and / or magnetic bank note features, but is particularly due to the components for checking security elements described in more detail below 5 awarded with optically variable effect.

To record and test such a security element 5 instructs the testing facility 2 preferably a light source 6 and two sensors 7 and 8th on. The testing facility 2 is used in particular to check the diffraction phenomena of diffraction structures 5 , such as holograms and / or kinegrams as a security element 5 that are inserted or applied in the banknote paper.

The light source 6 is an LED rows 6 with a single row of LED elements 6a , As an example, assume that the LED line 6 ver in time in a predetermined manner can radiate different colors. Alternatively, the individual LEDs 6a the LED line 6 also continuously emit white light. The LED line indicates the aperture limitation 6 a SELFOC lens 9 on. This aperture limitation serves only to narrow itself in the transverse direction of the banknote 3 to illuminate extending strips. To produce diffraction phenomena, this lighting strip should be larger than the lattice constant of the diffraction structure 5 , but significantly narrower than the smallest structure of the security elements to be resolved in the illustration 5 his. This has the advantage that the undesired influence of diffusely scattering areas of the banknote paper is reduced by the defined narrow illumination during the subsequent detection of the light emanating from the illuminated banknote.

The sensors 7 and 8th can be CCD or CMOS line sensors that are parallel to the LED line 6 extend. Typically the line sensors have 7 . 8th a resolution of 0.2 to 1 mm. In the case of irradiation with colored light in time-division multiplex operation, the sensors need 6 only a broadband detection sensitivity in the visible. Since only a single color is emitted and then recorded, color selection is not necessary in this case.

The first sensor 7 is used to detect light emanating from the transport direction X. With the banknotes after 1 for example, the light diffracted in the R1 direction. The second sensor 8th on the other hand serves for the detection of light emerging perpendicular to the transport direction X, ie in the transverse direction Y. With the banknotes after 1 for example, the light diffracted in the direction of R2. The sensors point to these light beams 7 and 8th also SELFOC lenses 9 , preferably the same as the LED line 6 on.

In order to avoid an oblique arrangement of the built-in optics and sensors, which is undesirable for the image generation described in more detail below, while at the same time being particularly compact in construction, the lenses are on the underside 9 Prisms, particularly advantageous Fresnel prisms 10 with a sawtooth profile 11 appropriate. The Fresnel prism has the required deflection 10 of the sensor 7 Steps across the longitudinal direction of the SELFOC lens 9 and the Fresnel prism 10 of the sensor 8th Steps in the longitudinal direction of SELFOC. The flat surface of the Fresnel prism 10 always points to the object to be checked, ie to the banknote 3 , because then the beam path through the prism 10 is more symmetrical. The existing dispersion of the prism 10 does not interfere in this case and can be neglected.

The sensor 8th with associated imaging optics 9 . 10 should be as close as possible to the lighting optics 6 . 9 be arranged. The aperture of the SELFOC lens 9 of the sensor 8th is then selected so that the sensor also directly through the level of the LED line 6 perpendicular to the transport direction X, ie in the direction R2 of the security element 5 outgoing light can be detected. The further sensor 7 again the LED line is ready 6 spaced apart so that it can detect the light emanating at a predetermined angle a to be detected in accordance with an expected direction of diffraction.

Alternatively or additionally, for the detection of diagonal diffraction light, for example, a further sensor line with Fresnel prism can be present on a SELFOC lens with steps below 45 ° to the SELFOC longitudinal direction, the distance to the lighting in turn being predetermined by the desired deflection angle to be detected. If the banknotes 3 alternatively transported with their long side forward, the arrangement of the sensors is rotated accordingly.

The length of the sensor surfaces, ie the measuring surfaces of the sensors 7 and 8th should be at least the length of the structures to be metered, ie the security elements 5 correspond. The detector surfaces will preferably have a length corresponding to the maximum banknote length in the transverse direction Y. The sensors 7 . 8th can be constructed identically in the 1 but the case is shown that the second sensor 8th longer than the first sensor 7 is. This can be due to the longitudinal deflection of the sensor 7 be necessary depending on the arrangement of the security elements to be tested 5 to be able to actually measure the light emerging perpendicular to the direction of transport X, ie in the longitudinal direction of the sensor, over the entire length.

The test facility described above 2 can be used as an example in the following way. banknotes 3 are individually by means of the transport device 4 at the test facility 2 transported over. The LED line is illuminated 6 the banknote transported underneath 3 line-shaped, ie stripe-shaped over its entire width in the Y direction, continuously with white light. The sensor line 7 detected from the bank note at an angle a to the perpendicular direction of radiation B. 3 outgoing light and close to the LED line 6 attached sensor line 8th the light emanating from the illuminated banknote strip in its longitudinal direction, ie in the Y direction. The two sensor lines 7 . 8th are read out electronically at a frequency which is substantially greater than the rate of the banknotes being transported past 3 at the test facility 2 is. The frequency should be high enough to read the sensor line sequentially 7 and / or 8 an image of the banknote being transported past 3 can be generated in which the structures of, for example, the security element to be recognized 5 can still be sufficiently resolved.

Through computer-based evaluation of the sensor measurement signals from the sensors 7 and / or 8 can thus be an image of the banknote 3 be generated. In the presence of a real banknote 3 should be in especially the image acquisition and evaluation of the sensor line 7 the presence of the hologram 5 with the representation of the expected number "50" in the appropriate position and shape. Since the direction of diffraction in the case of diffraction structures depends on the frequency, the sensor lines can 7 . 8th when irradiated with white light, optionally also include a color filter in order to obtain only the image for one of the illumination frequencies or a frequency range. Alternatively, light of a single color can be irradiated and the color filters can be dispensed with.

Furthermore, the lighting intensity of the LED line can be controlled by lighting or taking into account 6 characteristic quantity the intensity of the measurement signals of the line sensors 7 . 8th be standardized. Since, as already mentioned, the light intensity diffracted in the expected diffraction directions is significantly greater than the intensity at the same illuminance, which is only diffusely scattered, for example, by normal paper, this standardization can make a difference to non-diffractive structures and also optionally on the state of wear of the banknote 3 getting closed. This is possible even if only the signals of a single one of the two sensors arranged in different directions 7 . 8th be evaluated.

Should be by means of the test facility 2 not just a single, but several different security elements 5 checked, this can be done, for example, by the image acquisition described above, at least when the individual banknotes 3 differ only by the type of information shown in the diffraction direction R1, R2. The use of white light also has the advantage that such diffraction structures can also be obtained by comparing the measured signal strengths with the expected reference values 5 can be detected, the diffraction angle of only part of the illumination color, at least partly in the direction of that of the sensors 7, 8 bend solid angle range, each by the aperture size of the SELFOC lenses 9 is specified.

4 shows an alternative embodiment, which differs from that of 1 differs in that instead of a single line sensor 7 for identifying light diffracted in or against the direction of transport, three identically constructed line sensors 7, 7 ', 7'' are arranged side by side. For better clarity, the associated SELFOC lenses are 9 with Fresnel prism 10 not shown.

This embodiment with preferably two to four line sensors arranged side by side 7, 7 ', 7'' has the advantage that with a still very compact, simple and inexpensive construction, all line sensors 7 . 7 ', 7'' taken together can cover a larger solid angle range and thereby, for example, also by comparing the measured values of the individual sensors 7, 7 ', 7'' among themselves, diffraction structures with different diffraction characteristics can be recognized and distinguished.

In such a case in particular, lighting with an individual color or a constant frequency spectrum, but with different individually switchable colors in time-division multiplexing is advantageous. Because of the wavelength dependence of the diffraction, it can thus be particularly safe and unambiguous by comparing the measurement signals from the sensors 7, 7 ', 7'' for different colors can be checked for an expected diffraction characteristic. In this case, the data is recorded in time multiplex for different colors and the data lines are then sorted according to the lighting color and evaluated separately.

If the banknote to be checked 3 If the different colors illuminate several times at high frequency, the data lines corresponding to a green color, for example, become an image of the banknote 3 and the data lines corresponding to a red illumination for a further image of the banknote 3 composed and compared with each other and / or with predetermined reference values or images. Is, for example, by a previous outline measurement of the banknote to be checked 3 , the presumed location of the security elements to be checked 5 known, so is preferably only a restricted to the security element 5 lying measuring window evaluated.

A third embodiment shows the 5 , It differs from the previous ones in that not one light source and several sensors for different directions of reflection or diffraction, but rather two light sources arranged at different angles of illumination 16, 16 ' to illuminate the banknotes to be checked 3 available. The light sources 16, 16 ' are preferably constructed identically in order to ensure identical lighting conditions as possible. The light sources 16 . 16 ' can be incandescent lamps, which irradiate the banknote in alternating times. Alternatively, LED lines can be used 6 according to the previous embodiments as light sources 16 . 16 ' be used.

To capture the from the banknote 3 outgoing light is also a single sensor 17 , for example again a line sensor extending perpendicular to the transport direction X. 17 with an upstream SELFOC lens 9 and a deflecting prism 10 ' available. The light source 16 ' has the same angle to the perpendicular of the banknote plane as the light path to the sensor 17 while the second light source 16 has a larger angle, ie is arranged in a non-reflection direction.

By comparing the signal intensities, a check can be made in this case standardized elements 5 with an optically variable effect. If the signals from the sensor 17 for both lighting directions, ie for both light sources 16 . 16 ' , are approximately the same, it can be concluded that just a diffusely scattering area of the banknote 3 was checked. Is the signal when irradiated with the light source 16 ' we considerably larger than for the light source 16 , it can be concluded that there are specularly reflecting banknote areas. In counterfeit banknotes, for example, this can be metal surfaces which are intended to simulate the presence of a hologram or another security element with an optically variable effect. Are the two light sources 16 . 16 ' now just arranged so that a high diffraction intensity of a real security element to be recognized 5 when illuminated with the light source 16 is just bending in one direction by the sensor 17 is detected, in this case, the verification of a real banknote 3 , the signal values of the light source 16 larger than a false banknote, possibly even larger than that of the light source 16 ' his.

One advantage of this embodiment, among other things, is that only by comparing the signals from the sensor 17 for lighting with the light source 16 in relation to lighting with the light source 16 ' , for example by means of a signal difference formation, statements about the state of the illuminated area can be made. This makes it independent of the exact location of the banknote 3 , ie even if the illuminated area of a banknote to be checked 3 is not exactly horizontal, but is, for example, slightly curved or kinked, the signal difference in diffusely scattering areas is approximately zero, while larger values of the signal difference indicate diffractive or specularly reflecting areas of the banknote.

6 shows an alternative to 5 , in which in addition to one in relation to the sensor 17 light source arranged in the direction of reflection 16 ' , not just one, but several other light sources 16 are present that are in non-reflection directions. The light sources 16 . 16 ' are preferably adjacent to one another and are all activated one after the other for illumination in accordance with different angles. This can also be used for example in banknotes 3 a distinction is made which bend at different angles. In such a case, for example, the sensor 17 each a maximum of the intensity when illuminated with another of the multiple light sources 16 . 16 ' to have.

Some of the possible exemplary embodiments for testing diffraction structures have already been described above 5 as security elements 5 described with optically variable effect. These principles can also be used to test other security elements with an optically variable effect. When testing security elements 5 ' with a color change effect, the following approaches are particularly preferred.

While testing diffraction structures 5 the vertical lighting of the banknotes 3 is preferred, it has been shown that for testing security elements 5 ' with color change effect, the lighting should be at an angle to the BN vertical in order to be able to measure a sufficient color contrast. The azimuth of the lighting should, for example, be oriented perpendicular to the direction of the line in the case of line-shaped lighting, as exemplified in the 7 is indicated. Preferably, the oblique illumination in direction B 'is carried out by a light source, not shown, arranged vertically, such as an LED line again arranged perpendicular to the direction of transport X, the radiation of which, after passing through a SELFOC lens, emanates obliquely from a Fresnel prism in direction B' the banknote to be checked 3 is redirected.

A lighting control or reference for normalizing the measurement signals proves not to be absolutely necessary if, for example, a color difference measurement is carried out for evaluation. To carry out such a measurement should be from the banknote 3 be detected in the direction of illumination and outgoing light against the direction of illumination. Corresponding line sensors can in turn be attached perpendicular to the transport direction X for this purpose. In the 7 However, an alternative arrangement is shown, in which a prism, in particular a 90 degree prism, is used 13 , both in the direction of illumination RB and against the direction of illumination, ie in the direction RG of the banknote 3 outgoing light through the same prism 13 about SELFOC lenses 14 on two sensor surfaces 15 be redirected. Due to the beam deflection, the sensors can be installed at an angle 15 be avoided.

In the case of line sensors 15 as sensor surfaces 15 can be read out sequentially from the line sensors 15 when the banknote to be checked is transported past 3 two images of the security element 5 ' can be obtained from two different observation directions RB, RG. Because the color impressions in the directions RB, RG for real banknotes 3 can be different, by selecting the appropriate filter or when irradiating with an associated color or white light, by evaluating the difference signals of the two sensors 15 the presence of a security element 5 ' be closed with color change effect. High difference values will show up in the difference image in the areas in which the color change effect occurs. The size of the signals or their difference can in turn also be used as a criterion for checking the state of wear of the banknotes 3 serve.

Instead of using line-shaped lighting and / or line sensors, the banknote can 3 alternatively also illuminated over a large area and sensors with a two-dimensional detector surface can be used to directly image the illumination area.

The 8th shows a further embodiment, which differs from that of 7 differs in that instead of the 90 degree prism 13 with a triangular cross-section a space-saving Fresnel prism 13 ' is used with a step profile, which is designed so that both the light emanating in the RG direction and in the RB direction through a common SELFOC lens 14 ' on a single sensor 15 ' , such as a CCD camera 15 ' is imaged with a two-dimensional detector surface. This structure is particularly compact and simple.

In the embodiments according to 7 and 8th by means of a symmetrical beam path from the banknote 3 outgoing light rays produces two images that can be compared in a particularly simple manner, for example by pixel-by-pixel difference formation, due to essentially the same imaging parameters. The variant with a prism for generating two images corresponding to different viewing angles is also preferably suitable as a hand-held device for checking associated security elements, the eyes of the viewer functioning as the sensors 15 . 15 ' take.

So the device can be a housing with opaque walls include in which the prism and / or the light source are attached. The housing will preferably an opening for entering rays to illuminate the area to be tested and / or an opening for the exit of the rays passing through the prism. Furthermore, the housing one or more walls which has about the prism protrude to by putting the housing on one to be checked Security element a predetermined distance from the security element to ensure the prism.

It should be noted that in the embodiments of the 7 and 8th when illuminating with multicolored or white light, a color selection by the sensor due to the color differences to be measured in different directions 15 . 15 ' necessary is. Illuminating with a single color, however, can be enough if the security element 5 ' with color changes for these under the different detected directions of observation RB, RG provides a sufficiently large contrast.

The 9 shows a seventh embodiment in which the polarization behavior of security elements 5 . 5 ' is used to check their authenticity. As has been mentioned, the reflection or diffraction of linearly polarized light remains on security elements 5 . 5 ' maintain the polarization with optically variable effect and on intaglio printing profiles, whereas this is not the case with scattering on paper or with offset printing.

Using a light source 20 a linearly polarized light beam is perpendicular to the surface of the banknote in direction B. 3 directed. That from the illuminated banknote 3 outgoing light is detected obliquely in two symmetrical directions. For this purpose, sensors are constructed identically at a distance from one another 21 . 21 ' arranged on each, using a SELFOC lens 9 and a deflecting prism 10 ' , outgoing light is directed at an angle γ. The first sensor 21 includes a polarizing filter that transmits light that is polarized just like the illuminating light, while the other sensor 21 ' only transmits perpendicularly polarized light. The sensors 21 . 21 ' are preferred with the inputs of a differential amplifier 22 connected, the output signal of which is a measure of the change in polarization. In the presence of, for example, security elements 5 . 5 ' with an optically variable effect, the signal difference will be particularly high, for example.

Finally, in the 10 a last embodiment shown, the lighting and sensor arrangement essentially that of 9 equivalent. However, the testing facility 2 the 10 not designed to test polarization properties. Therefore, the banknotes to be checked 3 not irradiated with linearly polarized light in this exemplary embodiment and the sensors likewise do not have a polarization filter for detecting light of a specific polarization direction. The test facility also serves 2 not for testing security elements 5 . 5 with optically variable effect, but especially for the detection of surface profiles 25 of banknotes 3 , Such profiles 25 that in the 10 are shown greatly enlarged, for example line patterns or the like, which are produced by intaglio printing, the profiles extending, for example, perpendicular to the direction of transport X. The banknote 3 is arranged with a light source arranged transversely to the transport direction 30 illuminated in direction B in an area that should be narrower than the cross section of a profile line. Depending on whether the light beam is a hill or a valley or one of the flanks of the profile 25 hits, the light beam is preferred in another direction from the profile 25 reflected. The light reflected in two different oblique directions is in turn by two sensors arranged in different oblique directions 31 and 31 ' with deflection prisms and SELFOC lenses. In unity 22 a difference between the signals is formed. The difference signal then leaves again, taking into account the transport speed of the bank note to be checked 3 , on the shape of the surface profile 25 conclude.

It has been found that a recognition of such intaglio printing profiles by spot lighting and thus the scanning of a single track of the bank note running in the transport direction X. 3 is not sufficient. For the safe and precise detection of the shape of such Full-surface detection is necessary for surface profiles. That is why the light source 30 and the two sensors 31 . 31 ' particularly preferably line-shaped light sources 30 or sensors 31 . 31 ' his. In the example of 10 these can extend perpendicular to the sheet plane, ie perpendicular to the transport direction X in the Y direction.

For example, in comparison to the detection of diffraction structures, the following should be noted. In order to produce diffraction phenomena, it is imperative that the diffraction structures are illuminated in an area that is significantly larger than their grating constant. In contrast, the intaglio profiles 25 are preferably illuminated in an area that is smaller than the dimensions of the structures to be recognized, in particular, for example, smaller than the line spacing a of the profile 25 is.

It was described above that the pair of sensors 31 . 31 ' extends essentially perpendicular to the direction of transport. These or additional pairs of sensors could be used to identify other profile structures 31 . 31 ' extend in other directions. Furthermore, not only two, but several sensors can be used 31 . 31 ' be arranged in parallel in order to be able to cover a larger solid angle range.

Finally, it should be emphasized once again that several of the test facilities mentioned above 2 can be combined, for example by a test facility 2 above the transport level of the banknotes 3 for checking on the top of banknotes 3 diffraction structures 5 and another test facility 2 below to the transport level of the banknotes 3 for checking on the bottom of the banknotes 3 located security elements 5 ' is arranged with color change effect.

Claims (29)

Contraption ( 1 ) for processing value documents ( 3 ), with a test facility ( 2 ) to check a security element ( 5 . 5 ' . 25 ) of the value document ( 3 ), in particular to check the type and / or authenticity and / or fitness of a security element ( 5 . 5 ' ) with optically variable effect, characterized by one or more light sources ( 6 . 16 . 16 ' . 20 . 30 ) to illuminate the security element, one or more sensors ( 7, 7 ', 8, 15, 15', 17, 21, 21 ', 31, 31' ) for detecting the light emanating from an illuminated area of the security element in one or more different directions (RB, RG, R1, R2), which do not correspond to the direction of reflection (B), and a means ( 7 . 7 ', 8, 15, 15', 17, 21, 21 ', 31, 31' ) for capturing images of the illuminated area, the test being carried out as a function of signals from the sensors for capturing light emerging in the non-reflection direction and the means for capturing images. Device according to claim 1, characterized in that the means ( 7 . 7 ', 8, 15, 15', 17, 21, 21 ', 31, 31' ) is designed for image acquisition to generate one or more images of the illuminated area, each corresponding to a different viewing angle, and / or the means ( 7 . 7 ', 8, 15, 15', 17, 21, 21 ', 31, 31' ) a separate sensor or at least one of the sensors ( 7, 7 ', 8, 15, 15', 17, 21, 21 ', 31, 31' ) which are used for the detection of light emanating in the non-reflection direction. Device according to at least one of the preceding claims, characterized in that the device further comprises a transport device ( 4 ) to the documents to be checked ( 3 ) individually at the test facility ( 2 ) in a transport direction (X). Device according to at least one of the preceding claims, characterized in that the light sources line-shaped light sources ( 6 . 16 . 16 ' . 20 . 30 ) for line-shaped illumination of the document of value and / or the sensors line sensors ( 7 . 7 ', 8, 15, 15', 17, 21, 21 ', 31, 31' ) are. Device according to at least one of the preceding claims, characterized characterized that the light source and / or the sensors are each transverse, in particular perpendicular extend to the direction of transport (X). Device according to at least one of the preceding claims, characterized in that the length of the illuminated surface of the security element ( 5 . 5 ' ) and / or the length of the measuring surface of the sensors is greater than or equal to the length of the value documents to be measured in the same direction. Device according to at least one of the preceding claims, characterized in that the light source for the vertical illumination of the security elements, in particular for testing diffraction structures ( 5 ) as security elements or for obliquely illuminating the security elements, especially for testing security elements ( 5 ' ) with a color change effect. Device according to at least one of the preceding claims, characterized in that, in particular in the case of a light source illuminating in the vertical direction (B) ( 6 ), a line sensor ( 8th ) close to the light source for recording perpendicular to the transport direction (X) of the document of value to be checked ( 3 ) outgoing light is arranged. Device according to at least one of the above claims, characterized in that a further line sensor ( 6 ) is arranged to detect the light emanating in or against the transport direction (X) in a certain angular range (α). Device according to at least one of the preceding claims, characterized in that several further line sensors ( 6 . 6 ' ) are arranged next to one another, each of the further line sensors serving in each case to detect a different direction (α) from light emanating in or against the transport direction (X). Device according to at least one of the preceding claims, characterized in that, in particular in the case of a light source illuminating in the oblique direction (B '), a single sensor ( 15 ' ) or at least two separate sensors ( 15 ) for detecting in and against the oblique direction of illumination from the illuminated banknote ( 3 ) outgoing light are arranged. Device according to at least one of the preceding claims, characterized characterized in that at the exam Controlled variables and / or Measurands, e.g. to actual Illuminance, the light sources for normalizing the measurement signals of the sensors are taken into account become. Device according to at least one of the preceding claims, characterized in that the light source and / or the sensors SELFOC lenses ( 9 . 14 ) for imaging and / or aperture limitation. Device according to at least one of the preceding claims, characterized in that the light source and / or the sensors for beam deflection are a prism, in particular a Fresnel prism ( 10 . 13 ' ) or a prism with a triangular cross section, such as a 90 degree prism ( 10 ' ), exhibit. Device according to at least one of the preceding claims, characterized in that a flat surface of the Fresnel prism ( 10 . 13 ' ) the security element to be checked ( 5 . 5 ' . 25 ) is facing Device according to at least one of the preceding claims, characterized characterized that the light source for lighting with white Light or for lighting with multiple colors in time-division multiplex mode is designed. Device according to at least one of the preceding claims, characterized in that there are several light sources ( 16 . 16 ' ) for illuminating the security element in at least two different illumination angles. Device according to at least one of the preceding claims, characterized in that the device ( 1 ) is a banknote counting and / or sorting and / or depositing and / or withdrawing device. Device according to at least one of the preceding claims, characterized characterized that the light source and / or the sensors have color filters and / or the evaluation device is designed for spectral analysis to different color components, e.g. by forming a color difference between the sensor signals to be able to. Device according to at least one of the preceding claims, characterized in that the light source ( 20 ) emits linearly polarized light and the sensors ( 21 . 21 ' ) are designed to detect the polarization state of the light emanating from the document of value in order to be able to infer the nature and / or authenticity and / or state of the security element on the basis of the polarization behavior. Device according to at least one of the preceding claims, characterized characterized that the device furthermore a device for determining the position and / or the Outline of the value document and / or its security element in relation to the test facility comprises around the measurement window of the sensors depending to be able to determine the location or the outline. Device according to at least one of the preceding claims, characterized in that the test device ( 2 ) as security elements, especially surface profiles generated by intaglio printing ( 25 ) the value documents ( 3 ) checks. Procedure for processing value documents ( 3 ), with an examination of a security element ( 5 . 5 ' . 25 ) the document of value, in particular an examination of the type and / or authenticity and / or fitness of a security element ( 5 . 5 ' ) with an optically variable effect, characterized in that the test automatically as a function of a mechanical detection of the light emanating from an illuminated area of the security element in one or more different directions (RB, RG, R1, R2), which is not in the direction of reflection (B ) in combination with image acquisition of the illuminated area. A method according to claim 23, characterized in that the documents of value to be checked individually on a checking device ( 2 ) transported past and illuminated in the form of lines and by means of line sensors the light emerging in the different directions (RB, RG, R1, R2) is detected. Method according to claim 23 and / or 24, characterized in that the value documents in particular for checking diffraction structures ( 5 ) vertical and / or for testing security elements ( 5 ' ) are illuminated at an angle with the color change effect. Method according to at least one of claims 23 to 25, characterized in that that for exam the security element at oblique Illumination, in and against the oblique direction of illumination (B ') light emanating from the illuminated value document is detected. Method according to at least one of claims 23 to 26, characterized in that the value documents with white light or with several colors in time-division multiplexing with one or more light sources ( 16 . 16 ' ) are illuminated in at least two different lighting angles. Method according to at least one of claims 23 to 27, characterized in that that after lighting of documents of value with linearly polarized light the state of polarization of the light emanating from the value document is measured in order to the polarization behavior of the security element in its manner and / or to be able to infer authenticity and / or condition. Method according to at least one of Claims 23 to 28, characterized in that the test for testing surface profiles ( 25 ) the value documents ( 3 ), which were generated in particular by intaglio printing.