EP3825140A1 - Security mark, method for detecting a security mark and system for detecting a security mark - Google Patents

Abstract

Shown and described is a security mark (1) for application to a substrate, in particular a container or packaging, the security mark (1) having a planar first color element (3), the first color element (3) being designed when irradiated with light of a first wavelength range that contains light of a first wavelength to emit light with an emission wavelength different from the first wavelength, when irradiated with light of a second wavelength range that differs from the first wavelength range to allow the light from the second wavelength range to pass through be to preferably have a transmittance of at least 90%, and when irradiated with light from a third wavelength range that differs from the second wavelength range to absorb and / or reflect the light from the third wavelength range.

Description

The present invention relates to a security sign, a method for capturing a security sign and a system for capturing a security sign.

Some containers, reusable containers or packaging, such as bottles, cans, bags, boxes and other containers, can be returned after emptying and returned to a cycle and partially refilled. Often, when the filled container is sold, a deposit is retained with which the buyer is to be encouraged to return the emptied reusable container to a certain point. The return can take place automatically, in particular with machines or return machines, which reimburse the buyer for the withheld deposit. The returnable containers can have a security mark so that the returnee does not receive the deposit value without authorization. Numerous machines only reimburse the deposit value after the security mark has been positively checked to the person returning it.

The applicant is aware of security signs for application to a carrier, in particular on a container or packaging, the security signs having a first color element which is designed in the form of a flat surface. Such a security mark is, for example, from DE 10 2006 011 143 A1 known.

However, some of these security symbols cannot be distinguished from forgeries with sufficient certainty.

Task and solution

It is an object of the present invention to improve the distinguishability of such security symbols from forgeries.

This object is achieved by a safety sign (first aspect) according to claim 1, by a method for detecting a safety sign (second aspect) according to claim 6 and with a system for detecting a safety sign (third aspect) according to claim 15.

The security mark of the first aspect is suitable for application to a carrier, in particular to a container or packaging. The safety sign has a planar first color element. The first color element is designed to emit light with an emission wavelength different from the first wavelength when irradiated with light of a first wavelength range, also called the excitation wavelength range, which contains light of a first wavelength. In a preferred embodiment, the first wavelength is 450 nm and / or 626 nm, and the emission wavelength is 735 nm. When irradiated with the first wavelength, the first color element thus shows fluorescence with the emission wavelength.

When irradiated with light of a second wavelength range that differs from the first wavelength range, the first color element is designed to be permeable to the light from the second wavelength range, preferably to have a transmittance of at least 90%. However, it is also possible for the transmittance to be less than 90%, so that when irradiated with light from the second wavelength range, the first color element absorbs part of it. When irradiated with light from a third wavelength range that differs from the second wavelength range, the first color element can absorb and / or reflect the light from the third wavelength range.

• S1 Bestrahlen des Sicherheitszeichens mit Licht in einem ersten Wellenlängenbereich, auch Anregungswellenlängenbereich genannt, der Licht der ersten Wellenlänge enthält,
• S2 Bestrahlen des Sicherheitszeichens mit Licht aus einem zweiten Wellenlängenbereich und/oder mit Licht aus einem dritten Wellenlängenbereich, insbesondere während des Schrittes S1,
• S3 Erfassen von Licht, das von dem Sicherheitszeichen ausgeht, mit einer Sensoreinrichtung, insbesondere während der Schritte S1 und S2,

wobei der erste und der dritte Wellenlängenbereich von dem zweiten Wellenlängenbereich verschieden sind, und
wobei während des Schrittes S1 die Intensität des von dem Sicherheitszeichen ausgehenden Lichts innerhalb eines vierten Wellenlängenbereichs erfasst wird, der die Emissionswellenlänge enthält. In einer bevorzugten Ausführungsform kann auch hier die erste Wellenlänge 450 nm und/oder 626 nm sein, und die Emissionswellenlänge liegt bei 735 nm.The method according to the second aspect is used to detect a security mark, in particular to record the aforementioned security mark. The security mark has a planar first color element which is designed to emit light with an emission wavelength different therefrom when irradiated with light of a first wavelength. The procedure consists of the following steps:

• S1 irradiating the safety sign with light in a first wavelength range, also called the excitation wavelength range, which contains light of the first wavelength,
• S2 irradiating the security sign with light from a second wavelength range and / or with light from a third wavelength range, in particular during step S1,
• S3 Detection of light emanating from the security sign with a sensor device, in particular during steps S1 and S2,

wherein the first and third wavelength ranges are different from the second wavelength range, and
wherein during step S1 the intensity of the light emanating from the security sign is detected within a fourth wavelength range which contains the emission wavelength. In a preferred embodiment, the first wavelength can also be 450 nm and / or 626 nm here, and the emission wavelength is 735 nm.

The system of the third aspect is for detecting a security token. The system is preferably designed to carry out the aforementioned method. The system has a positioning device for receiving a carrier, preferably a container or packaging, and a light source which is designed to emit light onto a system-independent security mark in a first wavelength range, the first wavelength range, also called the excitation wavelength range, being a first wavelength and wherein the light source is configured to emit light onto the security sign in a second wavelength range and / or in a third wavelength range, the first and third wavelength ranges being different from the second wavelength range. The system further comprises a sensor device, the sensor device being designed to receive light emanating from the security sign in a fourth wavelength range which contains an emission wavelength that differs from the first wavelength. This system also includes an evaluation device which is designed to output a signal that is dependent on the intensity of the light falling on the sensor device in the fourth wavelength range.

When the security sign according to the invention is irradiated with light in the first wavelength range, it then emits light with an emission wavelength different from the first wavelength. The intensity of the light emitted with the emission wavelength can also be recorded and evaluated, whereby the security mark can be distinguished more reliably.

"Absorption" of light by the security mark or by a color element of the security mark in the sense of the present invention is to be understood as meaning that the security mark neither emits nor reflects the incident light in such a way that it can be measured or detected with conventional detectors used to detect security marks. would be detectable.

In the context of the invention, a distinction is made between the wavelength range visible to the human eye with wavelengths from 380 nm to 700 nm and a wavelength range from 280 nm to 1100 nm that can be detected by a sensor device.

Preferred Embodiments

Preferred embodiments are the subject of the dependent claims.

The security mark has at least one, in particular two-dimensional, first color element. The security sign can have a plurality of first color elements that are applied to the outer surface of the carrier (substrate), e.g. B. the container or the packaging, can be arranged adjacent to one another. The security mark, in particular its first color element, can be connected to the carrier or applied to an outer surface of the carrier. The security mark can be applied as a layer on the carrier, in particular on the outer surface, in particular printed or sprayed. The security mark can have a carrier element that can be mechanically connected or glued to the carrier. The carrier element can be a plastic or metal foil. The security mark, in particular having the carrier element, can have a layer thickness of 0.7 to 1.3 μm, in particular when it is applied to the carrier.

The first color element can initially be in liquid form, in particular with a solvent, or as a powder before the security mark is applied to the carrier. The first color element can have at least one alphanumeric character and / or a two-dimensional area. The first color element can in particular be applied to the carrier element as a layer.

The security mark can have positioning marks which are used to position the security mark or the carrier, e.g. B. the container or the packaging, in particular in a return machine, for an improved detection of the security symbol, are used. The security mark can have further color elements, in particular with an alphanumeric character, barcode and / or matrix code, which serve to distinguish the security mark from a forgery.

According to one embodiment, the first wavelength range, also called the excitation wavelength range, is between 280 nm and 700 nm, the first wavelength preferably being 450 nm and / or 626 nm. The security sign can be designed to emit visible light when it is irradiated with light of this first wavelength range. In particular, the emission wavelength can be 735 nm, which is emitted when the first color element is irradiated with light of this first wavelength range.

According to a further embodiment, the second wavelength range is in the infrared light range, in particular between 700 nm and 1100 nm. The security sign, in particular its first color element, can be designed to emit no light, in particular no visible light, when it is irradiated with light of this second wavelength range becomes. In particular, in this embodiment the incident light from the second wavelength range is transmitted to a certain first portion and absorbed to a certain second portion, the ratio of the first and second portion forming the transmittance.

According to another embodiment, the third wavelength range is in the visible range, in particular between 380 nm and 700 nm.

One embodiment of the security sign has a second color element which is designed to absorb and / or reflect light from the second wavelength range when the security sign is irradiated, the second color element being designed between the first color element and the substrate, e.g. B. the carrier to be arranged. The second color element can initially be in liquid form, in particular with a solvent, or as a powder before the security mark is applied to the carrier. The second color element can have at least one alphanumeric character and / or a two-dimensional area. The first and the second color element can form two layers of the security sign, wherein the second color element can be designed to be applied directly to the substrate. If the security sign has a carrier element, the second color element can be applied directly to the carrier element and the first color element can be applied to the second color element.

The first color element can be partially transparent to the light from the first wavelength range. In this embodiment, when the security sign is irradiated with light from the second wavelength range, the second color element can be detected by a sensor device. This is because the light of the second wavelength range can pass through the first color element, since this is permeable to light of the second wavelength range. This information about the second color element can additionally be used to determine the authenticity of a security symbol.

During steps S1, S2 of the method according to the invention, it is advantageous if an angle of incidence of the light of 45 ° on the security sign is avoided.

The light source can be designed to emit light exclusively with the wavelengths 450 nm, 550 nm, 626 nm and / or 900 nm.

• S5 Zuführen eines Trägers, vorzugsweise eines Behälter oder einer Verpackung, mit dem Sicherheitszeichen, insbesondere in einen Rückgabeautomaten,
• S6 Positionieren des Behälters derart, dass beim Bestrahlen des Sicherheitszeichen mit einer Lichtquelle von dem Sicherheitszeichen ausgehendes Licht bzw. elektromagnetische Wellen von einer Sensoreinrichtung erfasst werden können.

Während Schritt S5, kann der Behälter in einem sogenannten Nest des Rückgabeautomaten abgelegt werden. Die Schritte S5 und S6 können den Schritten S1 bis S3 vorausgehen. Mit diesen weiteren Schritten kann die Zuverlässigkeit des Verfahrens verbessert werden.One embodiment of the method has the following steps:

• S5 feeding a carrier, preferably a container or a packaging, with the security symbol, in particular into a return machine,
• S6 Positioning the container in such a way that when the safety sign is irradiated with a light source, light emanating from the safety sign or electromagnetic waves can be detected by a sensor device.

During step S5, the container can be deposited in a so-called nest of the return machine. Steps S5 and S6 can precede steps S1 to S3. With these further steps, the reliability of the method can be improved.

Another embodiment of the method according to the second aspect also has the following step:
S4 Detection of the shape of the safety sign on the basis of the light received during step S3 with the sensor device, which is signal-connected to an evaluation device (6).
In this way it can be ensured that only those security symbols are recognized as genuine whose shape or form corresponds to the original.

In one embodiment, the fourth wavelength range is different from the first wavelength range. In this embodiment, the light which is emitted by the color element of the security sign with the emission wavelength which is in the fourth wavelength range can be more easily distinguished from light which is reflected towards a sensor device when it is irradiated with light of the first wavelength range.

According to a further embodiment, the fourth wavelength range is different from the second wavelength range and from the third wavelength range. In this embodiment, the security sign can be irradiated with light from the second and third wavelength range without reflections towards the sensor device, with which light with the emission wavelength is detected, interfering with the detection of the intensity of the light with the emission wavelength. It is only necessary that the sensor device is designed, for example by means of a corresponding filter, in such a way that it is sensitive only to the fourth wavelength range.

One embodiment is characterized in that the first wavelength range, also called the excitation wavelength range, is between 280 nm and 700 nm, preferably the first wavelength being 450 nm and / or 626 nm.

In another embodiment, the second wavelength range is in the infrared light range, in particular between 700 nm and 1100 nm.

According to one embodiment, the third wavelength range is in the visible range, in particular between 380 nm and 700 nm.

A preferred embodiment is characterized in that the light source is arranged with respect to the security sign to be detected in such a way that the angle of incidence of the light on the security sign is different from 45 °.

In a further embodiment, a first temporal pulse pattern is impressed on the light from the first wavelength range during the irradiation. The first pulse pattern can have a time sequence of light pulses with pauses in between. The irradiation with light visible to the eye is preferably carried out according to the first pulse pattern. This makes it possible in a simple manner to distinguish the emitted light with the first emission wavelength detected therein from other detected scattered light in a sensor device. This is because the light that is due to the emission induced by the irradiation with light from the first wavelength range in the color element and that has the emission wavelength also necessarily has the first pulse pattern, so that it can already be identified by its temporal course.

One embodiment includes that a second temporal pulse pattern is impressed on the light from the second wavelength range during irradiation and / or a third temporal pulse pattern is impressed upon the light from the third wavelength range during irradiation, the second and third pulse patterns from each other and from the first temporal pulse pattern Pulse patterns are different. This makes it possible to distinguish the light of the second and third wavelength range backscattered from the security sign in a sensor device from one another and from the light with the emission wavelength through the respectively different temporal progression.

The sensor device can receive electromagnetic waves and can provide a signal proportional to the received intensity. It can have a CMOS sensor, a CCD sensor, a silicon-based sensor, a germanium-based sensor or a combination of these sensors.

In one embodiment, the light source has a first light source element, preferably one or more LEDs (Light Emitting Diode / light emitting diode), which can emit light in the first wavelength range and / or third wavelength range, and a second light source element, preferably one or more LEDs which can emit light in the second wavelength range. If a light source with LEDs is used, this can mean that the light of the first wavelength range emitted by the light source essentially only contains light with the first wavelength. This can also result in the light of the second and third wavelength range emitted by the light source essentially only containing light with the single wavelength, the wavelength of the light of the third wavelength range deviating from that of the first wavelength range.

The light source can, however, also be designed in such a way that it emits “white” light that includes the first, second and third wavelength ranges.

The system has a positioning device in which the carrier, so z. B. a container or packaging that can be used to place safety signs.

One embodiment of a system has a first optical filter which can be arranged at a first position between the light source and the positioning device and can be moved away from this position, the first optical filter being transparent to light of the first wavelength and opaque to light of the emission wavelength. Particularly when using a light source which emits “white” light, this prevents light with the emission wavelength from being able to strike the security sign, the reflection of which could interfere with the detection of the emitted light with the emission wavelength. In a further preferred manner, the first optical filter can be designed as a low-pass filter, preferably with a cut-off wavelength between 450 nm and 735 nm, more preferably between 626 nm and 735 nm.

A low-pass filter in the sense of the present invention is designed to allow light with a wavelength below a cut-off wavelength to pass almost unattenuated, while light with a wavelength above the cut-off wavelength is blocked. This means that the transmission coefficient, which indicates the ratio of the intensity of light after passing through the filter relative to the intensity before passing through the filter, is almost equal to one for wavelengths below the cutoff wavelength, while it is equal to zero above the cutoff wavelength. The cut-off wavelength is the wavelength at which the transmission coefficient in the area of the transition between the pass band and the blocking area assumes a value of 0.5.

A further embodiment of the system according to the invention is provided with a second optical filter which is arranged at a second position between the positioning device and the sensor device and can be moved away from this position, the second optical filter being transparent for light with the emission wavelength and for light from the first wavelength range, which has a wavelength outside a range around the emission wavelength, is opaque. In this embodiment, particularly when using a light source which emits “white” light, it is prevented that light that does not have the emission wavelength can be prevented from falling onto the sensor device. The second optical filter can preferably be designed in particular as a bandpass filter, the first cut-off wavelength being below the emission wavelength and the second cut-off wavelength above the emission wavelength.

A band-pass filter in the sense of the present invention is designed to block light with a wavelength below a first cut-off wavelength, while light with a wavelength above the first cut-off wavelength below a second cut-off wavelength can pass the filter almost unattenuated. Light with a wavelength above the second cut-off wavelength is in turn blocked. This means that the transmission coefficient, which indicates the ratio of the intensity of light after passing through the filter relative to the intensity before passing through the filter, is almost equal to zero for wavelengths below the first cut-off wavelength, while it is above the first cut-off wavelength and below the second cut-off wavelength is almost equal to one. Above the second cut-off wavelength, the transmission coefficient is equal to zero. Here, too, the limit wavelengths are the wavelengths at which the transmission coefficient assumes a value of 0.5 in the area of the transition between the pass band and the blocking areas.

In a further embodiment of a system, a first optical filter is provided, which is arranged at a first position between the light source and the positioning device and can be moved away from this position, the first optical filter being a low-pass filter, preferably with a cut-off wavelength between 450 nm and 735 nm, more preferably between 626 nm and 735 nm.

In addition, a second optical filter can be provided in this embodiment, which is arranged at a second position between the positioning device and the sensor device and can be moved away from this position and which can be used as a high-pass filter with a cut-off wavelength smaller than the emission wavelength and larger than the cut-off wavelength of the low-pass filter is designed.

A high-pass filter in the sense of the present invention is designed to block light with a wavelength below a cut-off wavelength, while light with a wavelength above the cut-off wavelength can pass the filter almost without attenuation. This means that the transmission coefficient, which indicates the ratio of the intensity of light after passing through the filter relative to the intensity before passing through the filter, is almost equal to one for wavelengths above the cutoff wavelength, while it is zero below the cutoff wavelength. Here, too, the cut-off wavelength is the wavelength at which the transmission coefficient assumes a value of 0.5 in the area of the transition between the pass band and the blocking area.

In this embodiment it is ensured that the radiation required to excite the emission of the light with the emission wavelength reaches the safety sign, but then only light with the emission wavelength reaches the sensor device.

A further preferred embodiment of a system according to the invention has a third optical filter which is arranged at a first position between the light source and the positioning device and can be moved away from this position and which is transparent to light from the second wavelength range and to light from the first and / or or third wavelength range is opaque. In this way, especially when using a light source that emits "white" light, it is ensured that only light from the second wavelength range, i.e. preferably infrared light, reaches the security sign, so that only this light can then reach the sensor device.

Furthermore, it is preferred if a fourth optical filter is provided in a system according to the invention, which is arranged at a second position between the positioning device and the sensor device and can be moved away from this position and which is transparent for light from the second wavelength range and for light from the first and / or third wavelength range is opaque. This also ensures that only light from the second wave range can reach the sensor device.

In a further preferred embodiment of a system according to the invention, the third and / or the fourth optical filter can be designed as a high-pass filter, preferably with a cutoff wavelength between 700 nm and 1000 nm.

Furthermore, in a further embodiment of a system according to the invention, a fifth optical filter can be provided, which is arranged at a first position between the light source and the positioning device and from this position can be moved away and which is transparent to light from the third wavelength range and opaque to light from the second wavelength range. In this way, especially when using a light source which emits “white” light, it is achieved that only light of the third wavelength range from the light source to the security sign and then also to the sensor device.

Furthermore, in a preferred embodiment of a system according to the invention, a sixth optical filter can be provided, which is arranged at a second position between the positioning device and the sensor device and can be moved away from this position and which is transparent for light from the third wavelength range and for light from the second Wavelength range is opaque. This also ensures that only light from the wavelength range reaches the sensor device.

In a further preferred manner, the fifth and / or the sixth optical filter can be designed as a low-pass filter, preferably with a cutoff wavelength between 700 nm and 1000 nm.

Embodiments

Fig. 1

ein erstes bevorzugtes Ausführungsbeispiel eines Sicherheitszeichens mit einem ersten Farbelement bei Bestrahlen mit sichtbarem Licht,

Fig. 2

das erste bevorzugte Ausführungsbeispiel bei Bestrahlen mit Licht der Wellenlänge 450 nm,

Fig. 3

das erste bevorzugte Ausführungsbeispiel bei Bestrahlen mit Licht der Wellenlänge 900 nm,

Fig. 4

eine schematische Darstellung der optischen Eigenschaften des Sicherheitszeichens aus den Fig. 1 bis 3,

Fig. 5a und 5b

ein zweites und drittes bevorzugtes Ausführungsbeispiel eines Sicherheitszeichens mit einem ersten und einem zweiten Farbelement unter Licht der Wellenlänge 900 nm,

Fig. 6

schematische Schnitte durch weitere Ausführungsbeispiele des Sicherheitszeichens und

Fig. 7

schematisch ein bevorzugtes Ausführungsbeispiel eines erfindungsgemäßen Systems zum Erfassen eines Sicherheitszeichens.

Further refinements and advantages of the invention emerge from the preferred exemplary embodiments described below. Show it

Fig. 1

a first preferred embodiment of a security sign with a first color element when irradiated with visible light,

Fig. 2

the first preferred embodiment when irradiated with light with a wavelength of 450 nm,

Fig. 3

the first preferred embodiment when irradiated with light with a wavelength of 900 nm,

Fig. 4

a schematic representation of the optical properties of the security sign from the Figs. 1 to 3 ,

Figures 5a and 5b

a second and third preferred embodiment of a security sign with a first and a second color element under light of the wavelength 900 nm,

Fig. 6

schematic sections through further exemplary embodiments of the safety symbol and

Fig. 7

schematically a preferred embodiment of a system according to the invention for detecting a security mark.

Fig. 1 shows an image of a first embodiment of a security sign 1 with a plurality of first color elements 3, which by way of example form an alphanumeric character sequence “lor”. The first color elements 3 are applied to a carrier (not shown) such as a packaging or a container, for example by printing, and are designed such that the first color elements 3 in the case of the in FIG Fig. 1 Irradiation shown with light from a so-called third wavelength range, here visible light, which here has wavelengths between 470 nm and 700 nm, appear black or dark to the human eye and also for a CMOS camera compared to the gray background. This is the case because the first color elements 3 absorb the light from the third wavelength range which is incident on them. The two dark triangles 5 form positioning marks and are designed here to absorb light between 300 nm and 1200 nm. The further color elements 7 of the safety sign 1, for example “PP2”, “P2”, appear black or dark when illuminated with light with wavelengths from the third wavelength range and also serve to distinguish them.

Fig. 2 FIG. 11 shows an image of the security token 1 of FIG Fig. 1 when irradiated with light of the first wavelength 450 nm from the so-called first wavelength range, which here extends between 280 nm and 700 nm. The first wavelength can also be 626 nm, for example. The first color elements 3 fluoresce during this irradiation in that they emit light with an emission wavelength, in the exemplary embodiment described here, 735 nm, and appear bright or white. The other color elements 7 (“PP2”, “P2”) and the triangles 5 appear black or dark, since they absorb the light from the first wavelength range or the first wavelength.

Fig. 3 FIG. 3 shows an image of the security token 1 from FIG Fig. 1 and 2 under light from the so-called second wavelength range, here the infrared range, with a wavelength of 900 nm. The first color elements are not recognizable because they do not differ in color from the gray background that is created by light from the second wavelength range that is backscattered on the carrier. Rather, they are permeable to the light from the second wavelength range, and in the embodiment described here, the transmittance for the light from the second wavelength range at 900 nm is at least 90%, ie the intensity of the light with the wavelength of 900 nm is after passing through the first color elements 3 still 90% of the intensity of the incident light. However, it should be pointed out that it is also possible that the degree of transmission in the first color elements 3 for the light from the second Wavelength range is less than 90%, so that when irradiated with light from the second wavelength range, the first color elements 3 absorb part of it. In this case, the first color elements 3 would stand out from the background in an image that is recorded when irradiated with light from the second wavelength range. The triangles still appear black or dark to the eye and the camera. The further color elements 7 “PP2”, “P2” are predominantly permeable to light of this wavelength and are hardly recognizable from the background.

The optical properties of the first exemplary embodiment of a security sign 1 and in particular those of the first color elements 3 are shown in FIG Fig. 4 once again shown schematically as a function of the wavelength of the light incident on the security sign 1 and emanating from it again.

Out Fig. 4 The following can initially be seen: When the first exemplary embodiment of a security sign 1 is irradiated with light from the first wavelength range W1, which contains the first wavelength A1, here visible light, the first wavelength A1 being 450 nm, the first color elements 3 emit as a result of the irradiation with light of the first wavelength A1, light with the emission wavelength A2, the emission wavelength A2 in the first exemplary embodiment being 735 nm. The first color elements 3 therefore show fluorescence with the emission wavelength A2 when irradiated with the first wavelength A1, as indicated by the arrow F in FIG Fig. 4 is indicated. In Fig. 4 it is also indicated that when the first color elements 3 are irradiated with light from the first wavelength range which contains a further first wavelength A1 of 626 nm, the first color element 3 then also shows fluorescence at 735 nm. This is illustrated by the arrow F.

Furthermore, in Fig. 4 to recognize that the light reflected back from the security sign 1 and in particular the first color elements 3 can be detected by means of a sensor device, the sensitivity of which is represented as a function of the wavelength by the curve labeled SE, it being possible to see that the sensor device ranges from the visible to in the infrared range is sensitive. In particular, the sensor device is sensitive over a larger area than is the case with the human eye, the sensitivity of which has the profile marked with v (λ).

Also is Fig. 4 it can be seen that when the first security mark 1 is emitted with light from a second wavelength range W2, which in the preferred exemplary embodiment described here comprises the infrared light range, in particular light with a wavelength between 700 nm and 1100 nm, this light forms the first color elements 3 happens almost without loss of intensity and is scattered back by the carrier arranged under the first color elements 3. This process is shown as an example for infrared light B with a wavelength of 900 nm. Since the light from the second wavelength range W2, in the present exemplary embodiment infrared light, is also scattered back from the areas of the security sign 1 that are free of the first color elements 3, whereby there is also no significant loss of intensity, the first color elements are 3 when irradiated with light from the second wavelength range W2 cannot be recognized in an image recorded by a sensor device and do not stand out from their surroundings. This is already in Fig. 3 has been shown.

After all, in Fig. 4 It can also be seen that when the first color elements 3 of the security sign 1 are irradiated with light from a third wavelength range W3, in the preferred embodiment described here, like the first wavelength range W1, visible light with a wavelength between 380 nm and 700 nm, the first Color elements 3 absorb the light of the third wavelength range and this is not scattered in the direction of a sensor device. This case is in Fig. 4 represented by the wavelength labeled "C" and corresponds to the image shown in FIG Fig. 1 is shown.

With regard to the irradiation of the security sign 1 with light from the second wavelength range W2, it should be pointed out that if a second color element is arranged below the first color elements 3 and on the carrier, light B from the second wavelength range W2, which is generated without loss of intensity first color element 3 happens, at which the second color element arranged below these is reflected back when the second color element is formed from infrared light reflecting color. Such a case will be discussed below with reference to FIG Figure 5a explained.

Thus, with reference to the Figs. 1 to 3 described first embodiment of a security sign 1 the following checks for authenticity:

When irradiated with light from the first wavelength range W1 with the first wavelength A1, here visible light with a first wavelength A1 of 450 nm, a sensor device, which if necessary through the use of a filter, is only sensitive to light with the emission wavelength A2, here 735 nm, it is checked whether the first color element 3 actually shows fluorescence and emits light of the emission wavelength A2 when it is irradiated with light from the first wavelength range W1.

In the event that the light source used for irradiation with light from the first wavelength range W1 is designed such that the first wavelength range W1 emitted by it is as in FIG Fig. 4 As shown extends far beyond the first wavelength A1, it makes sense that an optical filter in the form of a high-pass filter is arranged between the security sign and the sensor device, which blocks light with a wavelength below a cutoff wavelength and lets through light with a wavelength above the cutoff wavelength. The transmission of such a filter has the in Fig. 4 with OF designated course, its cutoff wavelength, as in Fig. 4 is then selected so that it is greater than the upper limit of the first wavelength range W1 and smaller than the emission wavelength A2. It is then realized that the optical filter is transparent to light with the emission wavelength A2 and opaque to light from the first wavelength range W1, which has a wavelength outside a range around the emission wavelength A2. Thus, only such light reaches the sensor device which has the emission wavelength A2, and the sensor device cannot be disturbed by scattered light which has a wavelength from the first wavelength range W1.

When the security sign 1 is irradiated with light from the second wavelength range W2, this passes through the first color elements 3 without significantly losing intensity and is scattered on the wearer towards the sensor device, while light from the second wavelength range W2 does not the first color elements 3 hits, is also scattered to the sensor device. It can therefore be checked whether, if so, to what extent, the first color elements 3 stand out from their surroundings when irradiated with light from the second wavelength range W2.

Finally, when the security sign 1 is irradiated with light from the third wavelength range W3, in which the first color element 3 absorbs the incident light, the shape of the first color element 3 can be checked by analyzing an image based on light from the third wavelength range has been detected by the sensor device.

Figures 5a and 5b show images under light from the so-called second wavelength range, here infrared light with a wavelength of 900 nm, of a second and third exemplary embodiment of a security sign 1, which have a two-layer structure. In addition to the aforementioned first color elements 3 in the form of the “lor”, which are not recognizable due to their permeability to light of the second wavelength range, these security symbols 1 also have second color elements 9. The second color elements 9 are below the "o" of the second for light Wavelength range permeable first color element 3 arranged. This means that the second color element 9 is arranged closer to the surface of the carrier, for example the container or the packaging, than the first color element 3. In the examples shown here, each of the second color elements 9 includes the character “X”.

The Figures 5a and 5b show how the second and third exemplary embodiment of a security sign 1 is detected when irradiated with light from the second wavelength range, that is to say in the exemplary embodiment described here, infrared light with a wavelength of 900 nm. As in the first exemplary embodiment, the first color elements 3 "lor" are permeable to the light of this wavelength and do not differ from the gray background formed by the carrier. As in the first exemplary embodiment, the further color elements 7 “PP2”, “P2” hardly stand out from the background formed by the carrier when irradiated with light from the second wavelength range. In the second embodiment ( Figure 5a ) but the second color elements 9 reflect the incident light passing through the first color element 3 and are clearly visible. In the third embodiment ( Figure 5b ) the second color elements 9 absorb the light passing through the first color element 3 and thus appear dark.

Fig. 6 shows cross-sections through several further exemplary embodiments of a security sign according to the invention. For better recognizability of the individual layers of the multilayer security signs shown here, the layers are shown spaced apart from one another, although in reality they are attached directly to one another. The carrier 13, that is to say for example a container or a packaging on which the security symbols can be applied, is only shown in part. The container can also have a rounded cross section.

The safety sign of a fifth embodiment ( Figure 6a ) has a carrier element 11 or carrier film, which can be connected to a carrier 13 in the form of a container. The first color element 3 is applied to the carrier element 11 and has the same properties as the first color element 3 of the first embodiment, ie when irradiated with light from the first wavelength range with the first wavelength it emits light with the emission wavelength and when irradiated with light It is permeable to the second wavelength range, so that in this case the carrier element 11 determines how the first color element 3 appears when irradiated with light of the second wavelength range, here infrared light. Finally, the first color element 3 absorbs when irradiated with light from the third wavelength range (see FIG Fig. 1 ).

The security mark 1 according to the sixth embodiment Figure 6b has only a first color element 3 and manages without a carrier element. The security mark 1 including the first color element 3 is applied directly to the outer surface of the carrier 13 or container, for example printed or sprayed through a mask. Here, too, the first color element 3 is designed in the way that has already been described in connection with the fifth exemplary embodiment. The structure of the sixth exemplary embodiment thus corresponds essentially to that of the first exemplary embodiment, which is described in connection with FIGS Figs. 1 to 3 has been described.

In the case of the safety symbol 1 of a seventh embodiment ( Figure 6c ) a first color element 3 is arranged over a second color element 9, so that the latter is arranged closer to the carrier 13 or container. When the security mark 1 is applied to the outer surface of the container 2, the second color element 9 is thus arranged between the outer surface of the carrier 13 or container and the first color element 3.

In the seventh embodiment according to Figure 6c the first color element 3 is configured in the same way as has already been described in connection with the fifth embodiment. The second color element 9 is also designed in such a way that it absorbs light from the second wavelength range, that is to say infrared light in the exemplary embodiment described here. This means that the second color element 9 appears dark in an image of the seventh exemplary embodiment, which is recorded when irradiated with infrared light. The structure of the seventh exemplary embodiment thus essentially corresponds to that of the fourth exemplary embodiment Figure 5b .

The safety symbol 1 of the eighth embodiment ( Fig. 6d ) is a combination of the fifth and seventh exemplary embodiment in that the security sign 1 according to the eighth exemplary embodiment has a first color element 3, a second color element 9 covered by it and a carrier element 11, the carrier element 11 being attached to the carrier 13 or the container. The first and the second color element 3, 9 are constructed in the way that has already been described in connection with the fifth and seventh exemplary embodiments.

The safety sign 1 of the ninth embodiment ( Figure 6e ) has two first color elements 3 and a second color element 9. One of the first color elements 3 covers the second color element 9, so that it is arranged between the first color element 3 and the carrier 13 in the form of the container 13. This ninth embodiment a security sign 1 can be applied directly to the outer surface of the carrier 13 or the container, in particular printed or sprayed, in two operations. Here, too, the first and the second color element 3, 9 are constructed in the way that has already been described in connection with the fifth and seventh exemplary embodiments.

Fig. 7 shows schematically an embodiment of a system for detecting a security token 1, which is attached to a carrier 13, for example in the form of a container.

In the exemplary embodiment described here, the system has a schematically illustrated housing 17, which prevents large amounts of scattered light from the environment from reaching the area of the system and influencing the detection of a security sign.

A positioning device 19 is provided within the housing 17 with which a carrier 13, for example a container or a packaging, can be positioned in such a way that a security mark 1 attached to the carrier 13 is arranged within the system so that it can be illuminated with light from a The light source 21 of the system 15 is irradiated and the light emanating from the security sign 1 during the irradiation can be detected by a sensor device 23 of the system 15. The positioning device 19 can be designed as a combination of conveyor belts and rollers, which make it possible to convey a carrier 13 in a longitudinal direction and to rotate it in the process. However, it is also possible for the positioning device 19 to be designed as a turntable with which the carrier 13 can be aligned. The present invention is also not restricted to the two aforementioned examples of positioning devices, but rather other devices can also be used which make it possible to align a carrier 13 with the light source 21 and the sensor device 23.

In the exemplary embodiment described here, the light source 21 can have a first light source element, preferably one or more LEDs, which can emit light in the first wavelength range. In the exemplary embodiment described here, the first wavelength range comprises light with wavelengths between 280 nm and 700 nm and in particular the first light source element, if it has LEDs, can essentially only emit light with a first wavelength of 450 nm. In addition, in the exemplary embodiment described here, the first light source element can emit light in the third wavelength range, namely in the preferred exemplary embodiment described here in the range between 380 nm and 700 nm, wherein the first light source element, in particular when it has LEDs, can essentially only emit light with a wavelength which, however, deviates from the first wavelength of 450 nm.

Furthermore, the light source 21 can have a second light source element, likewise preferably one or more LEDs, which can emit light in the second wavelength range, namely in the infrared range between 700 nm and 1100 nm.

The light source 21 can, however, also be designed in such a way that it emits “white” light which comprises the first, second and third wavelength ranges.

It is also possible that the light source elements of the light source 21 are designed in such a way that a first temporal pulse pattern is impressed on the light from the first wavelength range, a second pulse pattern on the light from the second wavelength range and a third temporal pulse pattern on the light from the third wavelength range, the pulse patterns being different from each other.

The sensor device 23 of the exemplary embodiment of the system can receive light emanating from the security sign 1 and in particular electromagnetic waves and can provide a signal proportional to the received intensity. It can have a CMOS sensor, a CCD sensor, a silicon-based sensor, a germanium-based sensor or a combination of these sensors. The sensor device 23 is finally connected to an evaluation device 25.

Finally, the light source 21, the positioning device 19 and the sensor device 23 are arranged in such a way that an angle of incidence on the security sign 1 of 45 ° is avoided. Furthermore, an angle of 90 ° between the light beam from the light source 21 and the light beam towards the sensor device 23 is likewise avoided in this preferred exemplary embodiment.

Furthermore, in the exemplary embodiment of a system according to the invention, a position P1 and a second position P2 are provided for optical filters, the first position P1 being arranged between the light source 21 and the positioning device 19 in such a way that light emitted from the light source 21 onto the security sign 1 a carrier 13 picked up by the positioning device 19 falls, passes the first position P1 and a filter arranged there. Similarly, the second position P2 is arranged in such a way that light emitted by a security sign 1 that is on a in the positioning device 19 arranged carrier 13 is attached, then goes out when the security sign 1 is irradiated by the light source 21, a filter in the second position P2 passes.

The exemplary embodiment of a system according to the invention can have a first optical filter 27 which can be arranged at the first position P1 between the light source 21 and the positioning device 23 and can be moved away from this position, i. H. it can be moved between the first position P1 and a position in which light from the light source 21 does not pass through the first filter when it reaches the positioning device 19. Furthermore, the first optical filter 27 is for light of the first wavelength, i. H. here 450 nm, transparent and for light of the emission wavelength, d. H. here 735 nm, impermeable. In particular, the first optical filter 27 can be designed as a low-pass filter, preferably with a cutoff wavelength between 450 nm and 735 nm, more preferably between 626 nm and 735 nm.

Furthermore, the exemplary embodiment of a system according to the invention can have a second optical filter 29, which can be arranged at the second position P2 between the positioning device 19 and the sensor device 23 and moved away from this position, particularly when using a light source 21 which emits "white" light . This means that the second filter 29 can be moved between the second position P2 and a position in which light from the positioning device 19 does not pass through the second filter when it reaches the sensor device 23. The second optical filter 29 is for light with the emission wavelength, i. H. here 735 nm, transparent and impermeable to light from the first wavelength range, which has a wavelength outside a range around the emission wavelength. In particular, the second optical filter 29 can be designed as a bandpass filter with a center wavelength that corresponds to the emission wavelength.

It is also possible that the first optical filter 27 is designed as a low-pass filter, preferably with a cut-off wavelength between 450 nm and 735 nm, more preferably between 626 nm and 735 nm, and the second optical filter 29 as a high-pass filter with a cut-off wavelength smaller than that Emission wavelength, d. H. preferably smaller than 735 nm and larger than the cut-off wavelength of the low-pass filter.

Furthermore, the exemplary embodiment of a system according to the invention can be provided with a third optical filter 31, particularly when using a light source 21 which emits "white" light, which, like the first optical filter 27, is arranged at the first position P1 and moves away from this position and the one for light is permeable from the second wavelength range and impermeable to light from the first and / or third wavelength range. In the exemplary embodiment described here, the third optical filter 31 is permeable to infrared light with a wavelength in the range of 700 nm and 1100 nm, while visible light with a smaller wavelength cannot pass through the third optical filter.

Furthermore, the exemplary embodiment of a system according to the invention can be provided with a fourth optical filter 33, especially when using a light source 21 which emits "white" light, which, like the second optical filter 29, is arranged at a second position P2 and moves away from this position and which is transparent to light from the second wavelength range, that is to say infrared light in the exemplary embodiment described here, and impermeable to light from the first and / or third wavelength range, in the exemplary embodiment described here, visible light. In particular, the third and / or the fourth optical filter 31, 33 can be designed as a high-pass filter, preferably with a cut-off wavelength between 700 nm and 1000 nm.

Furthermore, the exemplary embodiment of a system according to the invention can be provided with a fifth optical filter 35, especially when using a light source 21 which emits "white" light, which, like the first optical filter 27, is arranged at the first position P1 and moves away from this position and which is permeable to light from the third wavelength range, in the present exemplary embodiment visible light, and impermeable to light from the second wavelength range, in the present exemplary embodiment infrared light.

Finally, the exemplary embodiment of a system according to the invention can be provided with a sixth optical filter 37 which, like the second optical filter 29, can be arranged at the second position P2 and moved away from this position and which is for light from the third wavelength range, i.e. in the present case Embodiment is visible light, permeable and impermeable to light from the second wavelength range. In particular, the fifth and / or the sixth optical filter 35, 37 can be designed as a low-pass filter, preferably with a cutoff wavelength between 700 nm and 1000 nm.

In a preferred exemplary embodiment of a method according to the invention, the system 15 described above can be operated as follows to detect a security mark 1 on a carrier 13:

First, the carrier 13, i. H. a container or packaging, fed to the positioning device 19, for example by placing it on a conveyor belt, and arranged with the positioning device 19 in such a way that the security mark 1 attached to the carrier 13 is aligned so that light emanating from the light source 21 hits the security mark 1 hits and the incident light is scattered towards the sensor device 23.

In a first step S1, the security sign 1 is irradiated with light in the first wavelength range which contains light of the first wavelength. In the present exemplary embodiment, this is visible light, and the first wavelength is 450 nm. To achieve this, in the exemplary embodiment of a system according to the invention, the first optical filter 27 can be moved to the first position P1 so that the light from the Light source 21 has to pass through the first optical filter 27, which allows light of the first wavelength to pass through, but which is impermeable to light of the emission wavelength, here 735 nm.

In a step S2, the security sign 1 is irradiated with light from a second wavelength range and with light from a third wavelength range, parallel to step S1 or before or after it. In the present exemplary embodiment, the second wavelength range is in the infrared light range and the first wavelength range is in the visible range.

If steps S1 and S2 do not run in parallel, i.e. the light source 21 does not emit broadband light that extends from the visible range to the infrared range, the third filter 31 can initially be moved to the first position P1 and the fourth filter 33 during step S2 moved to the second position P2. Thus, only light from the second wavelength range, in the present exemplary embodiment infrared light, falls on the security sign 1, and only light coming from there in the second wavelength range, in the present exemplary embodiment also infrared light, reaches the sensor device 23.

Thereafter, during step S2, first the fifth filter 35 can be moved to the first position P1 and the sixth filter 37 can be moved to the second position P2. Thus, only light from the third wavelength range, in the present exemplary embodiment visible light, falls on the security sign 1, and only light coming from there in the third wavelength range, in the present exemplary embodiment also visible, reaches the sensor device 23.

During steps S1 and S2, the light emanating from the security sign 1 during the irradiation is detected with the sensor device in a step S3.

During step S1, i. H. During the irradiation with light from the first wavelength range, which contains the first wavelength, 450 nm in the exemplary embodiment, the intensity of the light emanating from the security mark 1 is detected by the sensor device 23 within a fourth wavelength range, which is the emission wavelength, 735 nm in the exemplary embodiment , contains. On the basis of this intensity and, if necessary, on the basis of the position in the image captured by the sensor device 23 at which this intensity occurs, the evaluation device 25 can determine, as a first authenticity criterion, whether the security mark 1 located on the carrier 13 in the positioning device 19 is genuine is.

Furthermore, in the exemplary embodiment described here, during step S2, when the security sign is irradiated with light from the second wavelength range, in the present exemplary embodiment infrared light, the shape of the security sign is determined with the sensor device 23, based on the light from the second wavelength range becomes. Since the first color element 3 is permeable to light from the second wavelength range, the shape determined in this way, which may be the shape of the second color element 9 (see FIG Figures 5a and 5b ) represented under the first color element 3, a further authenticity criterion can be checked by the evaluation device 25.

Finally, in the exemplary embodiment described here, during step S2, when the security sign is irradiated with light from the third wavelength range, in the present exemplary embodiment visible light, the shape of the security sign 1 is also determined with the sensor device 23, with the light from the third Wavelength range is used as a basis.

Since the first color element 3 absorbs light from the third wavelength range, it appears dark when irradiated with light from the third wavelength range. From the shape of the first color element 3 determined in this way, a third authenticity criterion can be checked by the evaluation device 25, or the shape of the first color element 3 when irradiated in the second and third wavelength ranges can be compared with one another as a further authenticity criterion.

If the light source 21 is designed as described above, the emitted light depending on whether light from the first, the second or the third Wavelength range is emitted with different temporal pulse patterns, the sensor device can also use these pulse patterns to determine in which wavelength range the light emanating from the security mark 1 and detected by the sensor device must lie. This makes it possible to dispense with some of the filters 27, 29, 31, 33, 35, 37. In the same way, the filters can be dispensed with if the light source 21 is designed in such a way, for example by using LEDs, that it only emits light with defined wavelengths from the wavelength ranges. If, for example, only light with the first wavelength is emitted, the first wavelength range then only contains one wavelength, it is only necessary to prevent the light of the first wavelength from reaching the sensor device 23. For this purpose, only one filter is then required at the second position P2 during step S1.

Overall, the use of the security sign 1 according to the invention with a first color element 3 which, when irradiated with a first wavelength, emits light with an emission wavelength that is different from the first wavelength, allows a further authenticity criterion to be checked.

Reference number

1

Safety sign

3

first color element

5

Triangle, positioning mark

7th

another color element

9

second color element

11

Support element

13th

carrier

15th

system

17th

casing

19th

Positioning device

21

Light source

23

Sensor device

25th

Evaluation device

P1

first position for one of the optical filters

P2

second position for one of the optical filters

27

first optical filter

29

second optical filter

31

third optical filter

33

fourth optical filter

35

fifth optical filter

37

sixth optical filter

W1

first wavelength range

W2

second wavelength range

W3

third wavelength range

A1

first wavelength

A2

Emission wavelength

B.

Infrared light

C.

visible light

SE

Sensitivity - sensor device

OF

Transmission coefficient - optical filter

F, F '

fluorescence

v (λ)

Sensitivity - human eye

Claims (21)

Safety mark (1) to be applied to a carrier (13), in particular to a container or packaging,
wherein the security sign (1) has a planar first color element (3),
wherein the first color element (3) is designed,
when irradiated with light of a first wavelength range (W1) which contains light of a first wavelength (A1), to emit light with an emission wavelength (A2) different from the first wavelength (A1),
when irradiated with light of a second wavelength range (W2), which preferably differs from the first wavelength range (W1), to be transparent to the light from the second wavelength range (W2), preferably to have a transmittance of at least 90%, and
when irradiated with light from a third wavelength range (W3), which differs from the second wavelength range (W2), to absorb and / or reflect the light from the third wavelength range (W3). Security sign (1) according to Claim 1, the first wavelength range (W1) being between 280 nm and 700 nm. Security sign (1) according to one or more of Claims 1 or 2, the second wavelength range (W2) being in the infrared light range, in particular between 700 nm and 1100 nm. Security sign (1) according to one or more of Claims 1 to 3, the third wavelength range (W3) being in the range visible to the human eye, in particular between 380 nm and 700 nm. Security sign (1) according to one or more of Claims 1 to 4, with a second color element (9),
which is designed to absorb and / or reflect light from the second wavelength range (W2) when the security sign (1) is irradiated, wherein the second color element (9) is designed to be arranged between the first color element (3) and the substrate. Method for detecting a security sign (1), preferably according to one of the preceding claims 1 to 5,
wherein the security mark (1) has a planar first color element (3) which is designed to emit light with an emission wavelength (A2) different therefrom when irradiated with light of a first wavelength (A1),
the method comprising the steps of: S1 irradiating the security sign (1) with light in a first wavelength range (W1) which contains light of the first wavelength (A1), S2 irradiating the security sign (1) with light from a second wavelength range (W2) and / or with light from a third wavelength range (W3), in particular during step S1,
wherein the first and the third wavelength range (W3) are different from the second wavelength range (W2), S3 Detection of light emanating from the safety sign (1) with a sensor device (23) during steps S1 and S2,
wherein during step S1 the intensity of the light emanating from the security sign (1) is detected within a fourth wavelength range which contains the emission wavelength (A2). The method of claim 6 further comprising the step of:
S4 Detection of the shape of the safety sign (1) on the basis of the light received during step S3 with the sensor device (23), which is signal-connected to an evaluation device (25). Method according to Claim 7, in which the light from the second wavelength range (W2) and / or the light from the third wavelength range (W3) are detected separately in order to detect the shape of the security sign (23). Method according to one or more of Claims 6 to 8, the fourth wavelength range being different from the first wavelength range (W1). Method according to one or more of Claims 6 to 9, the fourth wavelength range being different from the second and third wavelength ranges (W2, W3). Method according to one or more of Claims 6 to 10, the first wavelength range (W1) being between 280 nm and 700 nm. Method according to one or more of Claims 6 to 11, the second wavelength range (W2) being in the infrared light range, in particular between 700 nm and 1100 nm. Method according to one or more of Claims 6 to 12, the third wavelength range (W3) being in the visible range, in particular between 380 nm and 700 nm. Method according to one or more of Claims 6 to 13, wherein a first temporal pulse pattern is impressed and / or on the light from the first wavelength range during irradiation
during the irradiation, a second temporal pulse pattern is impressed on the light from the second wavelength range (W2) and / or
when the light from the third wavelength range (W3) is irradiated, a third temporal pulse pattern is impressed, the second and third pulse patterns being different from one another and from the first temporal pulse pattern. System for detecting a security mark (1) on a carrier, preferably on a container or a packaging, the system preferably being designed to carry out the method according to one of Claims 6 to 14, the system comprising: a positioning device (19) for receiving the carrier (13), preferably the container or the packaging, a light source (21), wherein the light source (21) is designed for emitting light onto the security sign (1) in a first wavelength range (W1), wherein the first wavelength range (W1) comprises a first wavelength (A1), preferably wherein the first wavelength 450 nm and / or 626 nm, and wherein the light source (21) is designed to emit light onto the security sign (1) in a second wavelength range (W2) and / or in a third wavelength range (W3), the first and third wavelength ranges (W1, W3) being different from the second Wavelength range (W2) are different, a sensor device (23) which is designed to receive outgoing light in a fourth wavelength range which contains an emission wavelength (A2) from a security sign which is attached to a carrier (13), preferably a container packaging, arranged in the positioning device, which differs from the first wavelength (A1), preferably where the emission wavelength (A2) is 735 nm,
and an evaluation device (6) which is designed to output a signal which is dependent on the intensity of the light falling on the sensor device (23) in the fourth wavelength range. System according to claim 15, wherein the light source (21) has a first light source element, preferably one or more LEDs, which can emit light in the first wavelength range (W1) and / or third wavelength range (W3),
wherein the light source (21) has a second light source element, preferably one or more LEDs, which can emit light in the second wavelength range (W2). System according to Claim 15 or 16, with a first optical filter (27) which can be arranged at a first position (P1) between the light source (21) and the positioning device (19) and can be moved away from this position, the first optical filter (27) is transparent to light of the first wavelength (A1) and opaque to light of the emission wavelength (A2). System according to one or more of Claims 15 to 17, with a second optical filter (29) which can be arranged at a second position (P2) between the positioning device (19) and the sensor device (23) and can be moved away from this position, wherein the second optical filter (29) is transparent for light with the emission wavelength (A2) and for light from the first Wavelength range (W1), which has a wavelength outside a range around the emission wavelength (A2), is opaque. System according to Claim 17, the first optical filter (27) being designed as a low-pass filter, preferably with a cut-off wavelength between 450 nm and 735 nm, more preferably between 626 nm and 735 nm, and
with a second optical filter (29) which is arranged at a second position (P2) between the positioning device (19) and the sensor device (23) and can be moved away from this position and which is a high-pass filter with a cut-off wavelength smaller than the emission wavelength (A2 ) and is designed to be greater than the cut-off wavelength of the low-pass filter. System according to one or more of Claims 15 to 19, with a third optical filter (31) which can be arranged at a first position (P1) between the light source (21) and the positioning device (19) and can be moved away from this position is transparent to light from the second wavelength range (W2) and opaque to light from the first and / or third wavelength range (W3), and / or
with a fourth optical filter (33) which is arranged at a second position (P2) between the positioning device (19) and the sensor device (23) and can be moved away from this position and which is transparent to light from the second wavelength range (W2) and is opaque to light from the first and / or third wavelength range (W1, W3). System according to one or more of Claims 15 to 20, with a fifth optical filter (35) which can be arranged at a first position (P1) between the light source (1) and the positioning device (19) and can be moved away from this position is transparent to light from the third wavelength range (W3) and opaque to light from the second wavelength range (W2),
and / or with a sixth optical filter (37) which is arranged at a second position (P2) between the positioning device (19) and the sensor device (23) and can be moved away from this position and which can be used for light from the third wavelength range (W3 ) is permeable and impermeable to light from the second wavelength range (W2).

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