WO1999041710A1 - Test method and device for verifying the authenticity of authenticity marks - Google Patents

Abstract

The invention relates to a method and device for verifying authenticity marks. The authenticity feature of the authenticity mark is a value of the slope, in a predetermined wavelength range, of the spectrum of the colour feature serving as authenticity feature. The measurements required for determining the value of the slope are obtained and evaluated by irradiating the authenticity mark with rays (a1, a2) of different wavelength ranges. Irradiation with rays of different wavelength ranges is preferably carried out in a time-division multiplex manner.

Description

 Test method and test facility for authenticity control by

Authenticity stamps

The present invention relates to a test method and a test device for checking the authenticity of authenticity marks, such as are provided as color marks on objects, in particular on documents, securities, and the like.

It is known from the prior art, in particular to provide printed products, such as preferably securities, banknotes and the like, with color features, in particular to print them, by means of which the authenticity of the object in question can be checked on the basis of an authenticity characteristic which has been conferred on them.

From DE-C-3020652 it is known to provide or use specially selected / manufactured printing inks for authenticity features / brands. The color samples, for example printed on a document and used for the test purpose, are illuminated, for example, by means of a xenon flash lamp. Because of the wavelength of such an irradiation, luminescence / fluorescence radiation is emitted / reflecting from these colors. This radiation is subjected to spectral analysis in a detector device and a decision is made based on the spectral analysis result as to whether this irradiated mark has the authenticity feature. Unfortunately, it is relatively easy for counterfeiters to analyze and imitate the dyes used for such printing inks for authenticity features. If this is achieved, the described system for authenticity checking can be undermined and practically worthless be made, although in addition to these specially produced printing inks, complex optics with various interference filters and the like have been used for the respective test equipment.

It is accordingly an object of the present invention to find an operating method for such a test device which does not require any particularly complicated optics and can be implemented in a simple manner with conventional electronic components. This device should preferably be light in weight, so that it can also be used in particular as a portable test device.

This object is achieved with the method according to claim 1 or the testing device according to claim 4, 5 in a further development according to the respective subclaims.

The invention is based on the finding that by in each case only narrow-band irradiation / excitation of the (color of) the authenticity mark in at least two mutually different (at most slightly overlapping) wavelength ranges with respective middle wavelengths which are spaced apart at a predeterminable wavelength distance and which characterize intensity values of the characteristic for this color Spectrum curve, ie the dependence of the intensity on the wavelength, or for the respective mean value of the respective narrow-band wavelength range, can be determined. From measurements in several, at least two such adjacent narrow wavelength ranges, a respective slope value of the characteristic spectrum curve of this color mentioned can then be determined and checked as an authenticity feature.

Further explanations of the method can be found in the description below of the test device operating according to the method according to the invention in its respective configuration. The recording of the characteristic spectrum curve of a color is per se customary in a different context and devices to be used for this are known. As already mentioned above, for the spectral analysis of a color either different wavelength-selective or optical devices tunable with respect to the wavelength selection are used on at least the transmitter or receiver side.

In contrast, the simplification on which the invention is based can be used in the invention to provide individual selective transmission wavelength ranges and to use detectors which are not necessarily wavelength-selective. The test device according to the invention is designed or is to be operated in such a way that the emission of radiation of different narrow wavelength ranges provided here is only time-multiplexed, i.e. according to a preferred variant of the test device. never occurs simultaneously for the different wavelength ranges. In the invention, different radiation sources, preferably luminescent diodes, which emit radiation of only narrow wavelength ranges at different wavelengths, are used, which can be switched in a simple manner in a time-multiplexed manner. Therefore, in this variant of the invention, a detector device can be used which does not have to have a wavelength-selective property. It is even advantageous to use a non-selective detector that is equally sensitive to all of the wavelength ranges provided. This saves corrections.

The test device working according to the invention is designed such that it carries out time-multiplexed transmission in selected, predetermined, narrow wavelength ranges and, with the detector arrangement, that of the irradiated authenticity feature at the respective time If (again) outgoing radiation falling into the detector is determined quantitatively, the respective steepness of the measurement signal curve can be reliably checked as a predefinable authenticity feature. This can be carried out with the invention with correspondingly low technical outlay. With the invention, printing inks that are different from one another, ie a real color with the authenticity feature, can be distinguished from another color that does not have this authenticity feature. This also applies if the broadband detector used in the invention has integral detection properties for both colors for the entire spectral range detected.

Further explanations of the invention are given on the basis of the figures, which are additional disclosure content of the invention.

Fig. 1 and la each show a schematic diagram of a device according to the invention. FIG. 2 shows a curve diagram of spectral reflection values of (printing) colors. Figure 3 shows a scheme for local distribution of

Color marks and their testing. Figure 4 shows an example of the optics of the device.

FIG. 1 shows the principle of a structure and the mode of operation of a test device 10 according to the invention in the most general form. 1 designates a control unit with which time-division multiplexing can optionally control one of the two transmitters 2χ and 2 ₂ for emitting radiation. When the transmitter 2χ is activated, it emits narrowband radiation ai. When the transmitter 2 ₂ is activated, the radiation a _{2 is} emitted from it. The two radiations ai and a ₂ differ in the mean wavelength value of their respective narrow (at most insignificantly partially overlapping) wavelength ranges. The two wavelength ranges have one for the construction of the Test device predeterminable distance from each other. For such “transmitters 2χ and 2 ₂ , semiconductor luminescent diodes are particularly suitable which have relatively narrow wavelength ranges of their emission, which are available in a corresponding selection and which can be operated easily in a time-multiplexed manner, ie in a time-selective manner.

The radiations ai and a ₂ are both aligned to one and the same surface element of an authenticity mark 3. Radiation b is emitted by this authenticity mark 3 both when irradiating ai and when irradiating a _{2, which} radiation is collected by a detector 4. Depending on whether it has been excited by radiation ai or a _2, this radiation b has a different wavelength (different wavelength range). However, since the detector 4 is broadband, regardless of whether irradiation ai or a _{2 has} occurred, it provides a respective detector signal which corresponds to the detected intensity of the radiation b received (at the corresponding time).

The output signals of the detector 4 go to an evaluation unit 5. This is communicated via the connection 6 from the control unit 1 which transmitter 2 or 2 _{2 is} emitting radiation at the moment, namely at the time the detector signal of the detector 4 is received in the evaluation unit 5 . In this way, the received signal of the detector 4 that came to the evaluation 5 at a specific point in time can be assigned to the respective transmission radiation a _x or a ₂ .

Connection 6 of FIG. 1 can be omitted if only two transmitters (2 1 and 2 ₂ ) are assigned to each detector (4).

The basic arrangement of FIG. 1 can also be equipped with further wavelength-selective transmitters (still other wavelength ranges) such as the transmitters 2 _X or 2 ₂ be, which is also time-division multiplex irradiate the surface element of the authenticity mark and also provide ^'for emitting radiation b occasion. This radiation then received in the detector 4 can also be assigned to the respective transmission wavelength range by means of the signal of the line 6.

Despite non-wavelength-selective detection, the invention allows the instantaneous detector signal to be unambiguously assigned to a specific wavelength range (the radiation ai or a ₂ or ....) due to the time-division multiplex operation in the evaluation unit 5. The measurement signals of the detectors are evaluated by the evaluation unit 5 according to their DC component and their AC component in the signal. From this, the courses in the spectrum of the radiation b in the relevant wavelength range can be assessed. On the basis of these dynamically recorded courses, a result-dependent output takes place through an output unit 7.

FIG. 2 shows the respective degree of reflection for three colors, depending on the wavelength. Here, curve 21 is the one that belongs to a specially selected black color that can be used as a selected authenticity feature. Such a second curve 22 of a corresponding second color (for a second / alternative selectable authenticity feature) is also specified. Curve 222 is the corresponding curve for another (usual) printing ink. In Figure 2, the mean wavelengths 20ι _m , 20 _{2m of} the narrow wavelength ranges 20ι and 20 _{2 of} the radiations ai and a _{2 are} marked. It can be seen from FIG. 2 ^' how different the reflection values, ie the respective intensity values of the radiation b, are when the respective color (time-multiplexed according to the invention) is irradiated with radiation ai on the one hand and with radiation a ₂ on the other. For the color (an authenticity mark) with the curve 21, the measured values 23 and 24 are obtained. These measured values represent the authenticity feature hidden in this color of the curve 21, that can be checked for the presence of the device of the invention. The second color with curve 22 gives completely different reflection values 123 and 124 for the wavelength ranges of the radiation a _x and a ₂ as second alternative authenticity feature. For the third curve 222 of another printing ink, reflection values 223 and 224 are obtained, for example. From the respective value pairs 23 and 24, 123 and 124 as well as 223 and 224 are obtained for the respective curve 21, 22 and 222, their respective mean slope between the wavelength values 20χ and 20 ₂ . Obviously, these slopes of these curves differ from each other. It is thus possible not only to distinguish the slopes of curves 21 and 22 as authenticity features from those of curve 222 of a normal printing ink, but also to distinguish those of curves 21 and 22 from one another as authenticity features that differ from one another.

A test device according to the invention can be operated in the ultraviolet, visible and / or infrared spectral range, adapted to the color of the authenticity feature.

The individual transmitters 2χ, 2 ₂ , ... of the transmitter arrangement 2 are arranged as spatially as possible adjacent in favor of a simplified structure with regard to the optical paths. For a detector 4, which consists of several individual detectors 4χ, 4 ₂ , ..., a similar structure is advantageous.

Another advantageous variant of the test device according to FIG. 1 is one according to FIG. 1 a with a detector arrangement 4 ′ which is selectively sensitive to the individual wavelength ranges 20ι, 20 ₂ , ... of the radiation ai, a ₂ , ..., namely instead of not being selective working detector arrangement 4 of Figure 1. This selective detector arrangement includes, for example, a corresponding number of individual selective detectors 4'ι, 4 ' ₂ , ..., which individually send their signal to the evaluation unit 5. In this variant, the The selective radiations a _x , a _{2 are} emitted simultaneously. Correspondingly, in response to this irradiation, the selective radiations bi, b ₂ , ... go from the authenticity feature to the detector arrangement and are there selectively picked up by the individual detectors 4ι ^' , 4 ₂ ^' , ... and in electrical signals for the evaluation unit 5 implemented. The selectivity of the individual detectors 4ι ^' , 4 ₂ ^' , ... can be caused by filters or based on the inherent selectivity property of the individual detectors. The connection 6 of Figure 1 can be omitted in the variant of Figure la.

According to the test result, which can be obtained by means of a test device operating according to the invention, at. Acknowledgment of authenticity ^' a signal to a unit

7, e.g. to peripheral devices, such as a printing unit

Locks or locks and the like forwarded to control the same. This unit 7 can be used to prepare the results of the evaluation for a

Control, signaling or alarming via e.g. electrical, optical and / or acoustic outputs can be formed. The evaluation results can also be saved as data and / or forwarded to central data processing.

With the invention, a local selection, based on a predetermined geometric arrangement of authenticity marks, can also be carried out, in particular as an additional measure of the authenticity check. For this purpose, FIG. 3 shows (as an example) two authenticity stamps 30χ, 30 ₂ with authenticity feature according to the invention, which are affixed in terms of area to one another on a ticket 32, for example. In the case of a test device 10 according to the invention, when a ticket of this type is inserted or pushed through (arrow 35) through the optical part 11 of the test device, the number of these authenticity stamps corresponding to the number one after the other (here two) approving signals from the evaluation unit 5, and only if these authenticity tags are authentic,

As a further increase in the precision of the authenticity check, it can be provided that these two authenticity marks 30χ, 30 ₂ (and possibly other such authenticity marks) also differ from one another. For example, the slopes of the spectrum curves 21, 22 (see FIG. 2) to be determined as the specified authenticity features can be selected differently for these two (and also for further) authenticity marks. When pushing through or checking such a ticket, such measured values must then be determined one after the other, precisely by the same transmitter / detector arrangement 2 and 4 of the checking device 10, and precisely in the sequence specified on the ticket result which correspond to the predetermined different slopes of the spectrum curves of the individual successive authenticity marks.

It is practically hopeless to want to outwit such an embodiment of the test device according to the invention with fake authenticity marks because the authenticity features are hidden in the authenticity marks, i.e. within e.g. black color is otherwise indistinguishable as authenticity marks are positioned on the ticket and, if necessary, their authenticity feature (gradient value) can also be different.

Instead of or in addition, chronological successive checking of authenticity marks can also take place simultaneously, namely if the testing device is equipped with several measuring stands distributed over the area, which at the correspondingly distributed locations on the document simultaneously carry out the testing process with sending and receiving the respective radiation and Execute evaluation of the result. 10

As explained, it can be determined with the invention in a simple manner and with simple equipment expenditure whether a e.g. black color has the authenticity feature 'or not, although this color forming the authenticity feature is visibly indistinguishable from other (e.g. black) color. This opens up the possibility of the authenticity feature in other, e.g. surface also printed in black color, e.g. not visible to the eye, locally hidden on e.g. attach a document.

The printing inks as an authenticity feature can be on, such as paper, plastic, textile _^ or the like is provided and / or in the carrier material. As described, they can be distributed as any geometric pattern and / or also (more or less) over the entire surface on / over the object. For example, the paper or the like can also be impregnated with the color bearing the color feature.

FIG. 4 shows (for example in addition to FIGS. 1 and 3) an example of the mutual arrangement of a transmitter arrangement 2 and a detector arrangement 4 and the authenticity mark 3 to be placed when the authenticity check is carried out. The directional radiation a of the respective wavelength range strikes the authenticity mark 3 on. The radiation b to be detected, which arrives in the detector arrangement 4, emanates from this. The other device details of this device for the authenticity check correspond to those which have already been described and explained for FIG. 1.

The invention has been described above for radiation b reflected by the authenticity mark. As an alternative to this, the method and the corresponding test device in its described variants can also work with radiation (b ') transmitted by the authenticity feature. Instead of recording the reflected radiation b with the detector 4 as in FIG. 4, the authenticity feature is required when working with transmission 11

radiation b 'that has penetrated with the correspondingly positioned detector.

Claims

1 2Patent claims Method for the authenticity check of a (respective) intended / certain authenticity feature which is contained (hidden) in a selected intended color spectrum of a color feature of the authenticity feature, this authenticity feature serving for an authenticity mark (3) which is used on objects, on documents and the like. is provided, characterized in that radiation (aa ₂ , ...) with at least two different discrete radiation wavelength ranges (20, 20 ₂ , ...) selected in relation to the color feature on or through the authenticity feature (3 is irradiated), and that, ...) towards outgoing radiation (b by this authenticity feature (3) on this irradiation (a ,, a _2; b, is ...) received by a detector arrangement (4) b _2, , in which the respective detector reception intensities assigned to the respective radiation (a _{1 f} a ₂ ,...) are determined and corresponding electrical signals of an evaluation for checking actually cher authenticity are supplied, for which purpose a gradient value of the curve (21, 22) of the color spectrum of the relevant color feature is determined as an authenticity feature from at least two of the reception intensities to be assigned to each of the wavelengths different from each other (a .., a ₂ , ...). 1 3 2. A method for the authenticity check of a (respective) intended / certain authenticity feature which is contained (hidden) in a selected color spectrum of a color feature of the authenticity feature, this authenticity feature serving for an authenticity mark provided on objects, on documents and the like is, with the method steps: that radiation (a _{1 (} a ₂ , ...) with at least two different discrete radiation wavelength ranges (20-,, 20 ₂ , ...) selected based on the color feature on or through the authenticity feature (3) is irradiated and that (... a ,, a ₂₎ towards outgoing radiation (b; b ₁ b _{# 2,} ...) of this authenticity feature (3) in this radiation by a detector arrangement (4 ) is recorded in which the respective detector reception intensities assigned to the respective radiation (a ,, a ₂ , ...) are determined and these are correspondingly supplied with electrical signals for evaluation, whereby to check the actual authenticity of a feature to be checked: for these radiations (a ,, a ₂ ) in the region of the slope (FIG. 2) the narrow-band wavelength ranges (20 _{1 f} 20 ₂ ) lying adjacent to the predetermined wavelength mean value (20 _1m , 20 _2m ) spacing and at most slightly overlapping wavelength ranges (20 _{1 f} 20 ₂ ) are selected from the reflection curve (21, 22) of the selected color spectrum and from these radiations ( a _1; a ₂ ) each to be assigned reception intensities and the gradient value of the (respective) curve (21, 22) of the color spectrum of the relevant color feature of the test object is determined as a verified authenticity feature from the wavelength _{mean value} distance (20 _{2 m} - 20 _{1 m} ). 1 4 3. The method according to claim 1 or 2, wherein the checking (Fig. 2, 3) of two provided as an authenticity feature, different color spectra (21, 22) is carried out, each with the same radiation (a, or a ₂ ) the one and the other color spectrum (21, 30,; 22, 30 ₂ ) are irradiated separately and the resulting slope values (23 or 24 and 1 23 or 1 24) are assigned from the respectively assigned two reception intensities (23 or 24 and 1 23 or 1 24) 23/24; 1 23/1 24) of these color spectra can be determined as the authenticity feature. 4. The method according to any one of claims 1 to 3, in which the emission of the wavelength-different radiations (aa ₂ , ...) is carried out alternately in a time-division manner. 5. The method according to any one of claims 1 to 3, in which the emission of the wavelength-different radiation (aa ₂ , ...) is carried out simultaneously and selective separation of the radiation received in the detector arrangement (b- ,, b ₂ , .. .) is made. 6. Device for the authenticity check according to the method of one of the claims 1 to 5, wherein this device comprises: an optical transmitter arrangement (2-,, 2 ₂ , ...) for the emission of radiation (a _{1 #} a ₂ , .. .) in at least two discrete radiation wavelength ranges (20, 20, 20 ₂ , ...) which are different from one another and which are selected based on the color feature, at least one optical detector arrangement (4) with sensitivity for at least these selected wavelength ranges (20) of radiation the transmitter arrangement, 1 5 it is provided that radiation (a) emitted by the transmitter arrangement (2) can selectively impinge on the authenticity feature (3) intended for the authenticity check and radiation (b) of the various discrete radiation wavelength ranges (20 ) arrives in the detector arrangement (4), where the respective reception intensity can be measured, an electronic evaluation unit (5) with which the respective electrical signals emitted by the detector arrangement (4) are proportional to those in the detector arrangement (4) as a result of the radiation (a,, _a2, ...) the received optical radiation (b) are processed into respective quantitative displays and a control unit (1) for the transmitter arrangement (2) for time-division transmission of radiation (a, a _2. ..) of a respective one of the wavelength ranges (20.,, 20 ₂ , ...). 7. Device for the authenticity test according to the method of one of the claims 1 to 5, this device comprising: an optical transmitter arrangement (2 _{1 f} 2 ₂ ) for emitting radiation (a,, a ₂ ) in at least two, in the area of Slope (FIG. 2) of the reflection curve (21, 22) of the color spectrum that is selected as the authenticity feature and is selected from different, selected, discrete, narrow-band, adjacent radiation wavelength ranges (20,, 20 ₂ ), a control unit (1) for the transmitter arrangement (2) for time-multiplexed emission of radiation (a,, a ₂ ) of a respective one of the wavelength ranges (20,, 20 ₂ ), at least one optical detector arrangement (4) with sensitivity for a total of at least these selected wavelength ranges (20) of the radiation of the transmitter arrangement, 1 6 it is provided that radiation (a) emitted by the transmitter arrangement (2) can selectively strike the feature (3) intended for the authenticity check and radiation (b) of the various discrete radiation wavelength ranges emanating from this as a result of this radiation (20) arrives in the detector arrangement (4), where the respective reception intensity can be measured, and an electronic evaluation unit (5) with which the respective electrical signals emitted by the detector arrangement (4), which are proportional to those in the detector arrangement (4 ) as a result of the radiation (a,, a ₂ ; 20 ,, 20 ₂ ) received optical radiation (b), the respective slope value (23/24; 1 23/1 24) of the (respective) curve (20, 21) of the (respective) color spectrum to be determined and checked as an authenticity feature. 8. Device for the authenticity test according to the method of one of the claims 1 to 5, wherein this device comprises: an optical transmitter arrangement (2,, 2 ₂ , ...) for the emission of radiation (a,, a ₂ , ... ) in at least two different, discrete radiation wavelength ranges (20,, 20 ₂ , ...) selected from one another based on the color feature, an optical detector arrangement (4 ') with selective sensitivity for these selected wavelength ranges (20) of the radiation of the transmitter arrangement, it is provided that radiation (a) emitted by the transmitter arrangement (2) can selectively impinge on the authenticity feature (3) intended for the authenticity check and radiation (b) of the various discrete radiation wavelength ranges (20 ) arrives in the detector arrangement (4 ') where 17 the respective reception intensity can be measured selectively, an electronic evaluation unit (5) with which the respective electrical signals emitted by the detector arrangement (4 '), which are selectively proportional to those in the detector arrangement (4') as a result of the irradiation (a,, a ₂ , ...) received optical radiation (b ,, b ₂ , ...) can be processed into respective quantitative displays. 9. Device for the authenticity check according to the method of one of the claims 1 to 5, wherein this device comprises: an optical transmitter arrangement (2 ,, 2 ₂ ) for the emission of radiation (a,, a ₂ ) in at least two, in the area of The slope (FIG. 2) of the reflection curve (21, 22) of the color spectrum that is selected as the authenticity feature and is selected from different, selected, discrete, narrow-band, adjacent radiation wavelength ranges (20, 20 ₂ ), an optical detector arrangement (4 ') with selective sensitivity for this selected wavelength ranges (20, 20 ₂ ) of the radiation from the transmitter arrangement, it being provided that radiation (a) emitted by the transmitter arrangement (2) can selectively impinge on the feature (3) intended for the authenticity check and as a result of this radiation again outgoing radiation (b) of the different discrete radiation wavelength ranges (20 ,, 20 ₂ ) in the Detektorano Wherever the respective reception intensity can be measured selectively, an electronic evaluation unit (5) with which the respective electrical signals emitted by the detector arrangement (4 '), which are selectively proportional to those in the detector arrangement (4') as a result, arrives the radiation (a,, a ₂ ) received optical radiation (b,, b ₂ ), the respective slope value (23/24; 1 23/1 24) of the (respective) curve (20, 21) of the (respective) color spectrum is to be determined and checked as an authenticity feature. 1 0. Device according to claim 8 or 9, the detector arrangement (4 ') comprises wavelength-selective detectors (4',, 4 ' ₂ , ...) which have this wavelength-selective property. 1 1. Device according to one of claims 6 to 1 0, with an optical configuration which allows radiation (b) reflected by the authenticity mark (3) to reach the detector arrangement (4, 4 '). 1 2. Device according to one of claims 6 to 10, with an optical configuration which allows radiation (b) which has passed through the authenticity mark (3) to reach the detector arrangement (4, 4 '). 1 3. Device according to one of claims 6 to 1 2, in which the evaluation unit (5) for evaluating the signals of the detector arrangement (4, 4 ') is designed according to the DC component and AC component of these signals. 14. Device according to one of claims 6 to 1 3, in which the authenticity mark in the device (Figure 3) is to be pulled. 1 5. Authenticity mark for a method according to one of claims 1 to 5 or for a test device according to one of claims 6 to 14, which is provided on / in the material of the object / document as a color feature. 19 16. authenticity mark according to claim 15, which is provided substantially over the entire surface on / in this material. 17. authenticity mark (32) according to claim 15, which is divided into surface elements (30 ,, 30 ₂ , ...) provided on / in the material. 18. authenticity mark (30 ,, 30 ₂ ) according to claim 17, in which for their individual portions (30 ,, 30 ₂ ) mutually different color spectra (21, 22) are provided as color features of the authenticity feature.