Sensor device for testing a data carrier having a luminescent feature, testing apparatus, and testing method

Abstract

The invention relates to a sensor device (20) for testing a planar data carrier (10), in particular a value document, having a luminescent feature (12), which sensor device comprises an excitation radiation source (22) for exciting the luminescent feature (12) and a detection device (26) for recording the signal radiation (28) emitted by the luminescent feature in response to the excitation of the luminescent feature by means of the radiation from the excitation radiation source. According to the invention, the detection device (26) contains at least two photodiode-based detection channels (32, 34) having different bandwidths.

Description

[0001] Sensor device for testing a data carrier with luminescence feature, test device and test method

[0002] The invention relates to a sensor device for testing a flat data carrier, in particular a value document, that has a luminescent feature. The invention also relates to a testing device with such a sensor device and a method for testing a flat data carrier equipped with a luminescent feature using such a sensor device.

[0003] To secure valuable documents and to verify their authenticity and / or classification, it is known to incorporate or apply machine-verifiable security features to valuable documents. Optical inspection is often used for machine verification. Machine-verifiable security features can, for example, be luminescent features, particularly luminescent features that are invisible to the human eye and emit in the infrared (IR) spectral range. Luminescent features that can be excited and emit in the infrared have proven particularly advantageous. The luminescent substances of the feature are preferably dosed as low as possible for reliable metrological detection in order to create a well-hidden security feature that is difficult for a potential counterfeiter to analyze.

[0004] During authenticity testing and / or classification, a valuable document is illuminated with excitation radiation by a sensor, and the radiation emitted by the valuable document is detected in order to determine the characteristic properties of the luminescent feature or the feature intensity. The general problem here is that for reliable detection of even small amounts of luminescent substance, a detector that is as sensitive and low-noise as possible must be used. On the other hand, it may be necessary for the sensor to operate quickly, i.e., to have good temporal resolution. However, these requirements are very difficult or impossible to meet simultaneously, so that a compromise between these two requirements must always be made for authenticity testing.

[0005] Based on this, the invention is based on the object of specifying a generic sensor device with which luminescence features can be reliably and accurately detected even when using small amounts of luminescent substance.

[0006] This object is achieved by the subject matter of the independent claims. Further developments of the invention are the subject matter of the dependent claims.

[0007] According to the invention, a sensor element for testing a planar data carrier with a luminescent feature comprises an excitation radiation source for exciting the luminescent feature and a detection device for receiving the luminescent or signal radiation emitted by the luminescent feature in response to the excitation of the luminescent feature by radiation from the excitation radiation source. The planar data carrier can, in particular, be a value document, for example a banknote. The detection device has at least two photodiode-based detection channels with different bandwidths. More precisely, the detection device has at least two detection channels, each of which has at least one photodiode and a signal processing device for processing signals from the photodiode and emitting a corresponding detection signal, wherein the signal processing devices have different bandwidths.The bandwidth is the electrical bandwidth.

[0008] By using multiple detection channels with different bandwidths, the invention circumvents the fundamental limitation that optical detectors can only be designed either faster or with lower noise. In practice, it has been shown that the invention can be implemented with particular advantage in a sensor whose digital signal processing system cannot or should not be designed to be powerful enough to emulate the low noise performance of a correspondingly dimensioned analog detection channel at a high sampling rate through digital signal post-processing such as filtering or averaging.

[0009] A further advantage of using different detection channels is the ability to select the electronic components of the detection channel with the lower bandwidth, in particular one or more operational amplifiers used there, with optimally matched properties, particularly with regard to inherent noise and / or power consumption. This allows a significantly lower noise level to be achieved than with conventional solutions with only a single high-bandwidth detection channel and digital signal post-processing.

[0010] In a preferred embodiment, the excitation radiation source is an infrared excitation radiation source and the photodiodes are infrared-sensitive photodiodes.

[0011] In an advantageous variant of the invention, the detection channels are designed to detect radiation in the same spectral range, in particular the same infrared spectral range. In this case, the detection channels advantageously each contain identical photodiodes.

[0012] In another, equally advantageous variant of the invention, the detection channels are designed to detect signal light in different spectral ranges, in particular in different spectral ranges in the infrared. In this case, the detection channels can contain identical photodiodes combined with different optical filters to detect different spectral ranges. However, the detection channels can also contain different photodiodes with different spectral sensitivities. For example, the different photodiodes contain materials with different doping or materials with different band gaps, such as Si and InGaAs.

[0013] It is advantageously provided that at least one detection channel, in particular its signal processing device, contains an amplifier stage with switchable bandwidth.

[0014] In a particularly advantageous embodiment, the two detection channels each contain an amplifier stage with individually adjustable gain and / or bandwidth, wherein each of the amplifier stages can be configured by switching resistors and capacitors of the respective amplifier stage on or off.

[0015] In a practical embodiment, a first of the detection channels has a smaller bandwidth, ranging between 2 kHz and 20 kHz, and a second of the detection channels has a larger bandwidth, ranging between 20 kHz and 200 kHz. In all embodiments, the ratio of the larger bandwidth to the smaller bandwidth is preferably between 2 and 20, particularly preferably between 5 and 10, including the respective limits. For example, the detection channel with the smaller bandwidth can have a bandwidth of 10 kHz, and the detection channel with the larger bandwidth can have a bandwidth of 20 kHz (ratio = 2) or even a bandwidth of 50 kHz (ratio = 5).

[0016] Furthermore, it can advantageously be provided that the detection channels, preferably their signal processing devices, have different amplification, wherein the ratio of the larger amplification to the smaller amplification is between 2 and 20, preferably between 5 and 10, limits in each case inclusive.

[0017] Even if designs with exactly two detection channels are described in this description for illustrative purposes, it is understood that the detection device can also contain more than two, for example three or four, detection channels of different bandwidths.

[0018] The invention also relates to a testing device for testing a flat data carrier equipped with a luminescent feature, in particular a value document, comprising a sensor device according to the invention and a transport device that introduces the flat data carrier to be tested along a transport path into an interaction zone in which the luminescent feature of the data carrier can be illuminated by the excitation light source and preferably the luminescence radiation excited in this way can be detected by the detection device, or guides the data carrier through the interaction zone. The invention also relates to a method for testing a flat data carrier equipped with a luminescent feature using a sensor element of the type described.In the method, the luminescence feature of the data carrier is exposed to excitation radiation, in particular in the infrared spectral range, the signal light emitted in response by the luminescence feature is recorded by a detection device which has at least two detection channels, each of which has at least one photodiode and a signal processing device for processing signals from the photodiode and emitting a corresponding detection signal, wherein the signal processing devices have different bandwidths and characteristic properties of the luminescence feature and / or a feature intensity are determined from the signals recorded by the at least two detection channels.

[0019] The luminescence feature is advantageously designed so that the emitted signal light, like the excitation radiation, lies in the infrared spectral range, which is not visible to human observers.

[0020] Further embodiments and advantages of the invention are explained below with reference to the figures, in which a true-to-scale and true-to-proportion reproduction has been omitted in order to increase clarity.

[0021] They show:

[0022] Fig. 1 schematically shows a checking device of a banknote processing system for checking or classifying a banknote, - 1 -

[0023] Fig. 2 is a schematic diagram showing a detection channel with a photodiode and an amplifier block and a digital signal processing system,

[0024] Fig. 3 is a schematic diagram with a detection channel as in Fig. 2, in which the first amplifier stage contains an additional second RC element which can be switched on by means of a switch,

[0025] Fig. 4 is a schematic diagram with a detection channel as in Fig. 3, extended by additional switchable RC elements,

[0026] Fig. 5 is a schematic diagram of a sensor device with two detection channels, and

[0027] Fig. 6 shows a concrete embodiment of a sensor device with two detection channels according to Fig. 2, and

[0028] Fig. 7 shows a concrete embodiment of a sensor device with a detection channel of lower bandwidth according to Fig. 2 and a detection channel of higher bandwidth according to Fig. 3.

[0029] The invention will now be explained using the example of authenticating value documents, in this case banknotes. Figure 1 schematically shows a checking device of a banknote processing system for checking and / or classifying a banknote 10, which is equipped with an IR-excitable and IR-emitting luminescent feature 12. The checking device contains a sensor device 20 and a transport device 21, which transports the value document 10 past the sensor device 20 in a transport direction T.

[0030] The sensor device 20 has an excitation radiation source 22 for exciting the luminescent feature 12 with excitation radiation 24 and a detection device 26 for receiving the luminescent radiation or signal radiation 28 emitted by the luminescent feature 12 in response. A control and evaluation unit 30 of the sensor device 20 serves to control the excitation radiation source 22 and the detection device 26, as well as to further process and evaluate the detected signals.

[0031] During the authentication or classification, the banknote 10 is illuminated by the excitation radiation source 22, here with IR excitation radiation 24, thereby stimulating the luminescent feature 12 to luminesce. The luminescent or signal radiation 28 emitted as a response by the luminescent feature 12 is recorded by the detection device 26, and the control and evaluation unit 30 determines characteristic properties of the luminescent feature 12 and / or the feature intensity from the detected signals. The characteristic properties or intensities thus determined are then compared with reference or threshold values ​​in order to assign the luminescent feature 12 and thus the banknote 10 to one of several predefined classes. In the case of an authentication, the banknote can, for example, be assigned to one of the two classes "genuine" or "suspected counterfeit."As a special feature, the detection device 26 contains two photodiode-based detection channels 32, 34, namely a first detection channel 32 with a lower bandwidth, preferably in the range from 2 kHz to 20 kHz, and a second detection channel 34 with a higher bandwidth, preferably in the range from 20 kHz to 200 kHz.

[0032] By using two detection channels 32, 34 of different bandwidths, the limitations mentioned above can be overcome and a detection device 26 can be provided which can detect the luminescence features 12 of the banknotes 10 both quickly and with high sensitivity.

[0033] In the design of Fig. 1, in one variant of the invention, the detection channels 32, 34 can each contain photodiodes designed to detect the same spectral range. The second detection channel 34 with a high bandwidth then serves to detect the dynamics, in particular the decay behavior of the emitted luminescence radiation, while the first detection channel 32, which is low-noise due to its lower bandwidth, allows for precise intensity determination.

[0034] Alternatively, the detection channels 32, 34 can also contain two photodiodes designed to detect different spectral ranges. This allows optimal adaptation of the detection to different luminescent substances with different decay times.

[0035] In this case, the photodiodes can be identical photodiodes with different filtering, but also different photodiodes, for example, made of materials with different doping or band gaps, such as Si and InGaAs. The detection device can also contain a detection channel with a switchable bandwidth, in particular two detection channels with individually adjustable bandwidths. The bandwidths can be configured as desired by connecting or disconnecting resistors and capacitors.

[0036] For a better understanding of the invention, basic properties and advantageous design variants of the detection device are explained in more detail below using the schematic diagrams in Figures 2 to 5. In particular, the detection channels 32 and / or 34 can be designed as described below. The same reference numerals are used for corresponding elements, and the explanations for these elements apply accordingly, unless otherwise stated. The excitation radiation sources of the sensor devices can be designed as described, but this is not necessary.

[0037] Fig. 2 shows a schematic diagram of a detection channel 42 with a photodiode 44 detecting the emitted signal radiation 28 and a signal processing device 40 comprising an amplifier block 46 and a digital signal processing system 60. The digital signal processing system 60 represents part of the control and evaluation unit 30 and, in particular, contains an analog-to-digital converter (ADC) 62 and a processor 64.

[0038] The amplifier block 46 contains a first amplifier stage 50 and an amplifier block 54. The first amplifier stage 50 is adjusted in gain and bandwidth via a resistor RI and a capacitor CI. The first amplifier stage 50 is designed as a transimpedance amplifier and causes the photodiode 44 to operate in a quasi-short circuit, which advantageously provides a linear conversion of the irradiance into an electrical current over several orders of magnitude.

[0039] Photodiode 44 can be operated in reverse polarity to adjust the required polarity of the output voltage of amplifier block 46. Photodiode 44 is advantageously operated with a reverse voltage (voltage source at the terminal not connected to operational amplifier 52) to reduce current change times or switching times.

[0040] The additional amplifier block 54 contains one or more amplifier stages whose gain and bandwidth are matched to the first amplifier stage 50 for optimal control of the ADC 62 of the digital signal processing system 60. The digital signal processing system 60 can be implemented, in particular, as a microcontroller, DSP, FPGA, or ASIC. The ADC 62 can be integrated into the digital signal processing system 60 or implemented as a separate component.

[0041] Figure 3 shows a schematic diagram of a detection channel 70 of a further sensor device, which is designed like the detection channel 42 in Fig. 2, but the signal processing device 40 is extended by a second RC element R2 / C2, which can be switched on by means of a switch S2, for static or dynamic switching of the gain and / or bandwidth of the first amplifier stage 50. Depending on the switch position S2, different values ​​for the gain and the bandwidth of the first amplifier stage 50 result:

[0042] S2 open: Gain = RI;

[0043] Bandwidth

[0044] S2 closed: Gain2 = RI | | R2 Bandwidth2 = 1 / (2K * RI | | R2 * (C1+C2)) where RI | | R2 = R1*R2 / (R1+R2) is defined.

[0045] "Gain" here refers to transimpedance. The ratios of gain 1 to gain 2 and bandwidth 1 to bandwidth 2 are advantageously between 2 and 20, especially between 5 and 10.

[0046] In an advantageous variant, resistor R2 is omitted, so only the bandwidth is switchable. The bandwidth of amplifier block 54 is then adjusted to the highest bandwidth of the first amplifier stage 50.

[0047] In another advantageous variant, the amplifier stages contained in the amplifier block 54 are designed to be switchable in terms of gain and / or bandwidth in a similar manner to the first amplifier stage 50 and are switched synchronously with the gain and / or bandwidth of the first amplifier stage 50. This allows maximum values ​​for the signal-to-noise ratio to be achieved at the different gain and bandwidth settings.

[0048] The reduction of the effective bandwidth at the input of the ADC 62 by the bandwidth of the amplifier block 54 must be taken into account when dimensioning the detection channel. Figure 4 shows a schematic diagram of a detection channel 72 of another sensor device, which is designed like the detection channel 70 in Fig. 3, but with the signal processing device 40 expanded by additional RC elements R3 / C3 to Rn / Cn, which can be switched on using switches S3 to Sn, for statically or dynamically switching the gain and / or bandwidth of the first amplifier stage 50 to more than two values.

[0049] The number n can be used to adapt to the number of applications of the detector, for example when checking valuable documents with different security features, or to adapt to the properties of different security features that are incorporated in a valuable document.

[0050] Finally, Figure 5 shows a schematic diagram of a detection device 80 of a sensor device with two detection channels 42-1, 42-2, each containing a photodiode 44-1, 44-2, an amplifier block 46-1, 46-2 according to one of the embodiments of Figures 2 to 4, and an AD converter (ADC) 62-1, 62-2. Unlike in the examples of Figures 2 and 4, the processors 64 are replaced by a common processor 64', which is not to be considered part of the detection channels 42-1, 42-2. Combinations that include different values ​​or value ranges of amplification and / or bandwidth are particularly advantageous.

[0051] The photodiodes 44-1, 44-2 can be operated as described above, and they can be identical or different photodiodes for identical or different spectral ranges, as already described in connection with Fig. 1. The amplifier blocks 46-1, 46-2 are each connected to an associated ADC 62-1, 62-2 of a digital signal processing system 60, which is connected to the processor 64'. Alternatively, a single, multi-channel ADC can also be used. Furthermore, instead of the shared processor 64', multiple processors 64 can be used for each ADC 62-1, 62-2.

[0052] Example 1:

[0053] In a further embodiment, a sensor device includes a detection device 82, schematically illustrated in Fig. 6, which has signal processing devices 40-1, 40-2 with two static detection channels 42-1, 42-2 according to Fig. 2, which enables a particularly simple and space-saving electronic circuit. As in the previous embodiment, the processors 64 of the embodiment in Fig. 2 are replaced by a common processor 64', which is not considered part of the detection channels.

[0054] The detection device of Fig. 6 is designed for the testing of two luminescence features, wherein a first luminescence feature emits after IR excitation in the infrared at a wavelength λ = 1030 nm with a decay time of 100 gs, and a second luminescence feature emits after IR excitation also in the infrared at a wavelength λ = 1200 nm with a decay time of 500 ps.

[0055] For both detection channels 42-1, 42-2, InGaAs photodiodes 44-1, 44-2 are used as photodiodes, which are equipped with spectrally different optical filters for detecting different spectral ranges. In the first detection channel 42-1, the photodiode 44-1 is equipped with an optical bandpass filter with a central wavelength of 1030 nm and an optical bandwidth of 20 nm. The electronic amplifier circuit of the first detection channel 42-1 is adapted to the decay time of the first luminescence feature and has a bandwidth of 10 kHz. For this purpose, the bandwidth of the first amplifier stage 50-1, consisting of the operational amplifier 52-1 and the parallel-connected components, is set to 20 kHz.Assuming a photodiode capacitance of 1 nF and a gain-bandwidth product (GBW) of 20 MHz for operational amplifier 52-1, this can be achieved, for example, using a resistor Rl-1 = 2 MΩ and a capacitor C1-1 = 3.9 pF. Rl-1 = 2 MΩ is identical to the transimpedance (gain) of the first amplifier stage 50-1. With an input noise voltage density of 6 nV / Hz for operational amplifier 52-1, an input-referred noise current of around 63 pA can be achieved.

[0056] In the second detection channel 42-2, the photodiode 44-2 is provided with an optical edge filter that only transmits light or radiation with wavelengths above 1100 nm. The electronic amplifier circuit of the second detection channel 42-2 is adapted to the decay time of the second luminescence feature and has a bandwidth of 2 kHz. For this purpose, the bandwidth of the first amplifier stage 50-2, consisting of the operational amplifier 52-2 and the components connected in parallel, is set to 4 kHz. Assuming a photodiode capacitance of 1 nF and a gain-bandwidth product (GBW) of 20 MHz for the operational amplifier 52-2, this can be achieved, for example, by using a resistor RI-2 = 18 M and a capacitor Cl-2 = 2.2 pF. Rl-1 = 18 MQ is identical to the transimpedance (gain) of the first amplifier stage 50-2.With an input noise voltage density of 6 nV / Hz of the operational amplifier 52-2, an input-referred noise current of around 6.5 pA can be achieved.

[0057] The amplifier blocks 54-1 and 54-2 then contain one or more amplifier stages whose gain and bandwidth are matched to the first amplifier stage 50-1 and 50-2, respectively, for optimal control of the ADCs 62-1, 62-2 of the digital signal processing system 60. Compared to identical electronic equipment in both detection channels, a better signal-to-noise ratio is achieved in the second detection channel.

[0058] Example 2:

[0059] In a further embodiment, a sensor device includes a detection device 84 illustrated in Fig. 7, which has, on the one hand, a slow, static detection channel 42-1 with a signal processing device according to Fig. 2 and, on the other hand, a fast, switchable detection channel 42-2 with a signal processing device 40 according to Fig. 3 or Fig. 4. In particular, two spectrally identical photodiodes 44-1, 44-2 can be used in the two detection channels. This enables advantageous adaptation of the fast detection channel to the luminescence feature to be measured.

[0060] Such a sensor device can be used, for example, to measure various luminescence features with an emission wavelength of 1030–1060 nm and a decay time of 50–500 gs. InGaAs photodiodes are used for both detection channels, optionally with a spectrally selective optical filter.

[0061] The first detection channel 42-1 is optimized for low-noise measurement of luminescence intensity and, for example, features a static circuit as shown in Fig. 2 with a bandwidth of 2 kHz. Due to the good signal-to-noise ratio, this detection channel enables reliable and reproducible measurements even of low luminescence intensities.

[0062] The second detection channel 42-2 is optimized for measuring the temporal behavior of the luminescence, in particular the decay times of the luminescence. Since luminescence features with different decay times are to be measured with the same sensor device, the second detection channel 42-2 is advantageously designed with a switchable bandwidth, for example, as shown in Fig. 3.

[0063] Specifically, electronic components with the following specifications can be used:

[0064] RI = 4 Mß, CI = 2 pF

[0065] R2 = 600 kN, C2 = 3 pF

[0066] Photodiode capacitance = InF

[0067] Gain-bandwidth product GBW (OP 52-2) = 50 MHz.

[0068] When switch S2 is open, a bandwidth of 10 kHz is achieved (bandwidth of the first amplifier stage is 20 kHz). In this state, the detection channel is used, for example, for luminescence features with decay times in the range of 150 gs - 500 gs. The measurement exhibits a particularly high signal-to-noise ratio, allowing even low-intensity luminescence features to be reliably measured.

[0069] When switch S2 is closed, a bandwidth of 30 kHz is achieved (bandwidth of the first amplifier stage is 60 kHz). In this state, the detection channel is used, for example, for luminescence features with decay times in the range of 50 gs - 150 ps. This allows measurement of the luminescence time response with particularly high time resolution. The transimpedance (gain) of the first amplifier stage S2-2 is 522 kΩ (parallel connection of R1 and R2). An input-referred noise current of around 500 pA is achievable.

[0070] If the multi-switchable amplifier circuit according to Fig. 4 is used for the second detection channel 42-2, an adaptation of the detector bandwidth to an even wider range of luminescence decay times is possible, or a more precise adaptation of the detector bandwidth to the decay time of the luminescence feature can be carried out.

[0071] List of reference symbols

[0072] Banknote

[0073] Luminescence feature

[0074] Sensor element

[0075] Transport device

[0076] Excitation radiation source

[0077] Excitation radiation

[0078] Detection device

[0079] Signal radiation

[0080] Control and evaluation unit

[0081] Detection channel with lower bandwidth

[0082] Detection channel with higher bandwidth

[0083] Signal processing device, 42-1, 42-2 detection channel, 44-1, 44-2 photodiode, 46-1, 46-2 amplifier block, 50-1, 50-2 first amplifier stage, 52-1, 52-2 operational amplifier, 54-1, 54-2 amplifier block

[0084] Digital signal processing system, 62-1, 62-2 Analog-to-digital converter, 64 z processor

[0085] Detection channel

[0086] Detection channel Detection device Detection device Detection device Transport direction

Claims

Patent claims 1. Sensor device (20) for testing a flat data carrier (10), in particular a security document, with a luminescence feature (12), with • an excitation radiation source (22) for exciting the luminescence feature (12), and • a detection device (26) for detecting luminescence radiation (28) emitted by the luminescence feature in response to the excitation of the luminescence feature by radiation from the excitation radiation source, and emitting detection signals, characterized in that • the detection device has at least two detection channels (42-1, 42-2), each having at least one photodiode (44) and a signal processing device (40) for processing signals from the photodiode (44-1, 44-2) and emitting a corresponding detection signal, wherein the signal processing devices have different bandwidths.

2. Sensor device (20) according to claim 1, characterized in that the photodiodes are infrared-sensitive photodiodes and preferably the excitation radiation source (22) is an infrared excitation radiation source.

3. Sensor device (20) according to claim 1 or 2, characterized in that the detection channels (32, 34; 70) are designed to detect radiation of the same spectral range, in particular the same infrared spectral range.

4. Sensor device (20) according to claim 1 or 2, characterized in that the detection channels (32, 34) are designed to detect signal radiation in different spectral ranges, in particular in different spectral ranges in the infrared.

5. Sensor device (20) according to claim 4, characterized in that the detection channels (32, 34) contain identical photodiodes which are combined with different optical filters in order to detect different spectral ranges.

6. Sensor device (20) according to claim 4, characterized in that the detection channels (32, 34) contain different photodiodes with different spectral sensitivities.

7. Sensor device (20) according to at least one of claims 1 to 6, characterized in that at least one detection channel (32, 34), preferably its signal processing device (40), contains an amplifier stage (50) with switchable bandwidth.

8. Sensor device (20) according to claim 7, characterized in that the two detection channels (32, 34) each contain an amplifier stage with individually adjustable gain and / or bandwidth, wherein each of the amplifier stages is configurable by connecting or disconnecting resistors and capacitors of the respective amplifier stage.

9. Sensor device (20) according to at least one of claims 1 to 8, characterized in that a first of the detection channels (32) has a smaller bandwidth which lies between 2 kHz and 20 kHz, and a second of the Detection channels (34) have a larger bandwidth, which lies between 20 kHz and 200 kHz.

10. Sensor device (20) according to at least one of claims 1 to 9, characterized in that the ratio of the larger bandwidth to the smaller bandwidth is between 2 and 20, preferably between 5 and 10, preferably limits in each case inclusive.

11. Sensor device (20) according to at least one of claims 1 to 10, characterized in that the detection channels (32, 34) have different amplifications, the ratio of the greater amplification to the smaller amplification being between 2 and 20, preferably between 5 and 10, preferably in each case including the limits.

12. Testing device for testing a flat data carrier (10) equipped with a luminescent feature (12), in particular a value document, with a sensor device (20) according to one of claims 1 to 11 and with a transport device (21) which introduces the flat data carriers (10) to be tested along a transport path into an interaction region in which the luminescent feature (12) of the data carrier can be illuminated by the excitation radiation source (22) or guides them through the interaction region.

13. A method for testing a flat data carrier (10) equipped with a luminescent feature (12) by means of a sensor device (20) according to one of claims 1 to 11, in which the luminescent feature (12) of the data carrier (10) is exposed to excitation radiation (24), in particular in the infrared spectral range, the signal radiation (28) emitted by the luminescence feature (12) in response is received by a detection device (26) having at least two detection channels, each having at least one photodiode (44) and a signal processing device for processing signals from the photodiode and emitting a corresponding detection signal, wherein the signal processing devices have different bandwidths, and characteristic properties of the luminescence feature and / or a feature intensity are determined from the signals received by the at least two detection channels (32, 34).

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