Sensor device, testing device and testing method for testing data carriers having luminous features

Abstract

The invention relates to a sensor device (20) for checking a planar data carrier (10) having a luminescent feature (12), in particular a value document, comprising an excitation radiation source (22) for exciting the luminescent feature (12) and a detection device (26) for detecting signal radiation (28), the signal radiation is emitted by the luminescent feature in response to the excitation of the luminescent feature by the radiation of the excitation radiation source, provision is made according to the invention that the detection device has at least two photodiode-based detection channels (32, 34), which have different bandwidths.

Description

[0001] This invention relates to a sensor device for inspecting planar data carriers with luminescent features, particularly valuable documents. The invention also relates to an inspection apparatus having such a sensor device and a method for inspecting planar data carriers equipped with luminescent features using such a sensor device.

[0002] To ensure the security of valuable documents and to verify their authenticity and / or classify them, it is known to incorporate machine-verifiable security features into or on the documents. Machine verification typically employs optical verification. Machine-verifiable security features can be, for example, luminescent features, particularly those emitting light in the infrared (IR) spectral range that are invisible to the human eye. Luminescent features that can be both excited and emitted in infrared light have proven particularly advantageous. The dosage of the luminescent material is advantageously set low enough to still enable reliable measurement verification, resulting in well-concealed security features that are difficult for potential forgers to analyze.

[0003] In authenticity verification and / or classification, a valuable document is illuminated by a sensor with excitation radiation, and the radiation emitted from the valuable document is detected to determine the characterizing properties or characteristic intensity of the luminescence features.

[0004] A common problem here is that, in order to reliably detect trace amounts of luminescent material, the most sensitive and lowest-noise detector possible must be used. On the other hand, the sensor may need to operate very quickly, i.e., it must have good temporal resolution. However, these requirements are difficult or impossible to meet simultaneously, so a trade-off must always be made between these requirements for authenticity verification.

[0005] Based on this, the technical problem to be solved by the present invention is to provide a sensor device of the type described in the present invention, which enables reliable and error-free detection of luminescent features even when a small amount of luminescent material is used.

[0006] The technical problem described herein is solved by the subject matter of the independent claims. Improvements to the invention are the subject matter of the dependent claims.

[0007] According to the present invention, a sensor device for inspecting a planar data carrier with luminescent characteristics has an excitation radiation source for exciting the luminescent characteristics and a detection device for acquiring the luminescent radiation or signal radiation emitted by the luminescent characteristics in response to the excitation of the luminescent characteristics by radiation from the excitation radiation source. The planar data carrier can be, in particular, a valuable document, such as a banknote. The detection device here has at least two photodiode-based detection channels with different bandwidths. More precisely, the detection device has at least two detection channels, each having at least one photodiode and a signal processing device for processing the photodiode signals and outputting a corresponding detection signal, wherein the signal processing device has different bandwidths. Here, bandwidth refers to electrical bandwidth.

[0008] By using multiple detection channels with different bandwidths, this invention circumvents the fundamental limitation that optical detectors can only be designed to be faster or lower noise. In practice, this invention has proven particularly advantageous for implementation in sensors whose digital signal processing system can, or should not, be designed to be so high-performance that it can simulate the low-noise characteristics of analog detection channels of a design size through digital signal post-processing, such as filtering or averaging, at high sampling rates.

[0009] Another advantage of using different detection channels is that the electronic components with low-bandwidth detection channels, especially the one or more operational amplifiers used, can be selected to have optimized matching characteristics, particularly in terms of inherent noise and / or power consumption. This enables a much lower noise level than traditional solutions with only a single detection channel that has high bandwidth and digital signal post-processing.

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

[0011] In an advantageous variant of the invention, the detection channels are designed to collect radiation within the same spectral range, particularly the same infrared spectral range. In this case, the detection channels advantageously each contain the same photodiode.

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

[0013] Advantageously, at least one detection channel, in particular its signal processing device, includes an amplifier stage with switchable bandwidth.

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

[0015] In a suitable implementation, the first detection channel in the detection channels has a smaller bandwidth of 2 kHz to 20 kHz, and the second detection channel in the detection channels has a larger bandwidth of 20 kHz to 200 kHz.

[0016] In all design schemes, the ratio of the larger bandwidth to the smaller bandwidth is preferably 2 to 20, and more preferably 5 to 10, wherein boundary values ​​are included. For example, a detection channel with a smaller bandwidth may have a bandwidth of 10 kHz, while a detection channel with a larger bandwidth may have a bandwidth of 20 kHz (ratio = 2) or even 50 kHz (ratio = 5).

[0017] Furthermore, it can be advantageously specified that the detection channel, preferably its signal processing device, has different gains, wherein the ratio of the larger gain to the smaller gain is 2 to 20, preferably 5 to 10, with boundary values ​​included respectively.

[0018] Although an embodiment with exactly two detection channels has been described in this specification for illustrative purposes, it should be understood that the detection device may also include more than two, such as three or four detection channels with different bandwidths.

[0019] The technical solution of the present invention also lies in an inspection device for inspecting planar data carriers equipped with luminescent features, especially valuable documents. The inspection device has a sensor device and a transmission device according to the present invention. The transmission device introduces the planar data carrier to be inspected into an interaction region or guides it through the interaction region along a transmission path. In the interaction region, the luminescent features of the data carrier can be irradiated by an excitation light source, and preferably the luminescent radiation excited in this manner can be detected by a detection device.

[0020] The present invention also relates to a method for inspecting a planar data carrier equipped with luminescent features using a sensor element of the aforementioned type. In this method, excitation radiation, particularly in the infrared spectral range, is applied to the luminescent features of the data carrier. A detection device collects the signal light emitted in response to the luminescent features. This detection device has at least two detection channels, each having at least one photodiode and a signal processing device for processing the signals from the photodiodes and outputting corresponding detection signals. The signal processing devices have different bandwidths, and the characteristic properties and / or feature intensity of the luminescent features are determined based on the signals collected by the at least two detection channels.

[0021] The luminescence characteristic is advantageously designed such that the emitted signal light, like the excitation radiation, is within the infrared spectrum invisible to human observers.

[0022] Other embodiments and advantages of the invention are described below with reference to the accompanying drawings, which are not reproduced to scale for improved clarity.

[0023] in:

[0024] Figure 1 The illustration schematically shows the inspection device of a banknote processing system used for inspecting or sorting banknotes.

[0025] Figure 2 The schematic diagram shows a detection channel, which includes a photodiode, an amplifier module, and a digital signal processing system.

[0026] Figure 3 It shows having, as Figure 2 The schematic diagram of the detection channel shows that the first amplifier stage includes an additional second RC component that can be switched on.

[0027] Figure 4 It shows having, as Figure 3 The schematic diagram of the detection channel has been updated, with the addition of an additional RC component that can be connected.

[0028] Figure 5 The schematic diagram of a sensor device with two detection channels is shown, and

[0029] Figure 6 It shows that according to Figure 2 Specific embodiments of a sensor device with two detection channels, and

[0030] Figure 7 A specific embodiment of a sensor device is shown, the sensor device comprising, according to Figure 2 The lower bandwidth detection channel and according to Figure 3A high-bandwidth detection channel.

[0031] The present invention will now be described using the verification of the authenticity of valuable documents, such as banknotes, as an example. Figure 1 For this purpose, an inspection device is schematically shown for inspecting and / or classifying banknotes 10 equipped with luminescent features 12, which are capable of being excited and emitted in IR.

[0032] The inspection device includes a sensor device 20 and a transmission device 21, which transmits the valuable document 10 from the sensor device 20 in the transmission direction T.

[0033] The sensor device 20 has an excitation radiation source 22 for exciting the luminescent feature 12 by excitation radiation 24, and a detection device 26 for acquiring the luminescent radiation or signal radiation 28 emitted by the luminescent feature 12 in response to the excitation radiation. The control and analysis unit 30 of the sensor device 20 is used to control the excitation radiation source 22 and the detection device 26, and to further process and analyze the detected signal.

[0034] During the authenticity verification or classification process, banknote 10 is irradiated by excitation radiation source 22 through excitation radiation, specifically IR excitation radiation 24, thereby stimulating the luminescent feature 12 to emit light. The luminescent feature 12, as a response to the emitted luminescent radiation or signal radiation 28, is acquired by detection device 26, and control and analysis unit 30 determines the characterizing properties and / or intensity of the luminescent feature 12 based on the detected signal. The determined characterizing properties or intensity are then compared with reference values ​​or thresholds to classify the luminescent feature 12, and thus the banknote 10, into one of several predetermined categories. In the case of authenticity verification, for example, the banknote may be classified into one of two categories: "genuine" and "suspected counterfeit."

[0035] As a feature, the detection device 26 includes two photodiode-based detection channels 32 and 34, specifically a first detection channel 32 having a lower bandwidth preferably in the range of 2 kHz to 20 kHz, and a second detection channel 34 having a higher bandwidth preferably in the range of 20 kHz to 200 kHz.

[0036] By using two detection channels 32 and 34 with different bandwidths, the limitations mentioned at the beginning can be overcome, and a detection device 26 can be provided that can detect the luminous features 12 of banknote 10 quickly and with high sensitivity.

[0037] exist Figure 1In one embodiment of the design, detection channels 32 and 34 may each contain photodiodes designed to detect the same spectral range. The second detection channel 34, with its high bandwidth, is used to examine dynamic characteristics, particularly the attenuation behavior of emitted luminous radiation, while the first detection channel 32, with its lower bandwidth and low noise, enables accurate intensity measurement.

[0038] Alternatively, detection channels 32 and 34 may also include two photodiodes designed to test different spectral ranges. This allows for optimized testing of different luminescent materials with varying decay times.

[0039] In this case, the photodiode can be the same type of photodiode with different filters, or it can be different photodiodes, such as different photodiodes made of materials with different doping or different band gaps, such as Si and InGaAs.

[0040] The detection device may also include detection channels with switchable bandwidth, particularly two detection channels with individually adjustable bandwidth. The bandwidth can be configured as needed by switching resistors and capacitors on or off.

[0041] To better understand this invention, the following references are made. Figures 2 to 5 The schematic diagram illustrates the basic characteristics of the detection device and advantageous design variations in more detail. Detection channels 32 and / or 34 can be constructed in particular as described below. The same reference numerals are used for the corresponding components, and the description of these components applies accordingly unless otherwise described. The excitation radiation source of the sensor device can be constructed as described, but this is not necessary.

[0042] Figure 2 A schematic diagram of a detection channel 42 is shown, which has a photodiode 44 for detecting emitted signal radiation 28 and a signal processing device 40, which includes an amplifier module 46 and a digital signal processing system 60. The digital signal processing system 60 forms part of the control and analysis unit 30 and specifically includes an analog-to-digital converter (ADC) 62 and a processor 64.

[0043] Amplifier module 46 includes a first amplifier stage 50 and an amplifier module 54.

[0044] The first amplifier stage 50 adjusts the gain and bandwidth via resistor R1 and capacitor C1. The first amplifier stage 50 is designed as a transimpedance amplifier and operates the photodiode 44 in a quasi-short-circuit state, which advantageously provides a linear conversion of irradiance to current over several orders of magnitude.

[0045] Photodiode 44 can operate with reverse polarity to adjust the polarity of the output voltage of amplifier module 46 as required. Advantageously, photodiode 44 operates with a reverse voltage (a voltage source at a terminal not connected to operational amplifier 52) to reduce current change time or switching time.

[0046] Another amplifier module 54 includes one or more amplifier stages adapted to the first amplifier stage 50 in terms of gain and bandwidth to optimally control the ADC 62 of the digital signal processing system 60. The digital signal processing system 60 can be designed in particular as a microcontroller, DSP, FPGA, or ASIC. The ADC 62 can be integrated into the digital signal processing system 60 or designed as a separate component.

[0047] Figure 3 A schematic diagram of the detection channel 70 of another sensor device is shown, which is as follows: Figure 2 The detection channel 42 is constructed as described above, but the signal processing device 40 adds a second RC element R2 / C2 that can be switched on by switch S2, which is used to statically or dynamically switch the gain and / or bandwidth of the first amplifier stage 50.

[0048] Depending on the position of switch S2, the gain and bandwidth of the first amplifier stage 50 have different values:

[0049] S2 disconnected: Gain 1 = R1;

[0050] Bandwidth 1 =

[0051] S2 closed: Gain 2 =

[0052] Bandwidth 2 =

[0053] Among them, the definition .

[0054] "Gain" should be understood here as transimpedance. The ratio of gain 1 to gain 2 and the ratio of bandwidth 1 to bandwidth 2 are preferably 2 to 20, especially 5 to 10.

[0055] In a favorable variation, resistor R2 is omitted, so only the bandwidth is switchable. The bandwidth of amplifier module 54 is then adapted to the highest bandwidth of the first amplifier stage 50.

[0056] In another advantageous variation, the amplifier stage included in amplifier module 54 is designed to be switchable in terms of gain and / or bandwidth in a manner similar to that of the first amplifier stage 50, and switches synchronously with the gain and / or bandwidth of the first amplifier stage 50. This allows for the achievement of maximum signal-to-noise ratio values ​​for different gain or bandwidth settings.

[0057] The reduction in the effective bandwidth at the input of the ADC62 due to the bandwidth of amplifier module 54 must be taken into account when designing the size of the detection channel.

[0058] Figure 4 A schematic diagram of the detection channel 72 of another sensor device is shown, which is as follows: Figure 3 The detection channel 70 is constructed as shown, however the signal processing device 40 adds additional RC elements R3 / C3 to Rn / Cn that can be switched on by 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.

[0059] The quantity n can be adapted to the number of application scenarios of the detector, for example, when examining valuable documents with different security features, or it can be adapted to the characteristics of different security features introduced into the valuable documents.

[0060] Figure 5 Finally, a schematic diagram of a detection device 80 with two detection channels 42-1 and 42-2 is shown. The detection channels respectively include photodiodes 44-1 and 44-2. Figures 2 to 4 One embodiment includes amplifier modules 46-1 and 46-2 and analog-to-digital converters (ADCs) 62-1 and 62-2. Figure 2 and 4 Unlike the previous example, processor 64 is replaced by a common processor 64', which is not considered part of detection channels 42-1, 42-2. It is particularly advantageous here to use combinations of different values ​​or ranges of values ​​that include gain and / or bandwidth.

[0061] Photodiodes 44-1 and 44-2 can operate according to the above description, and can be similar or different photodiodes used for the same or different spectral ranges, such as in combination. Figure 1 As stated above.

[0062] Amplifier modules 46-1 and 46-2 are respectively connected to the corresponding ADCs 62-1 and 62-2 of the digital signal processing system 60, which are connected to the processor 64'. Alternatively, separate multi-channel ADCs can be used. Furthermore, instead of using a common processor 64', each ADC 62-1 and 62-2 may use multiple processors 64'.

[0063] Example 1:

[0064] In another embodiment, the sensor device includes a detection device 82, which detects... Figure 6 The diagram schematically illustrates that the detection device includes two... Figure 2The signal processing devices 40-1 and 40-2 for the static detection channels 42-1 and 42-2 achieve a particularly simple and space-saving electronic circuit. Similar to the aforementioned embodiments, Figure 2 In the embodiment, processor 64 is replaced by a common processor 64', which is not considered part of the detection channel.

[0065] Figure 6 The detection device is designed to examine two luminescent features, wherein the first luminescent feature is emitted at an infrared wavelength of λ=1030nm after IR excitation and has a decay time of 100µs, and the second luminescent feature is also emitted at an infrared wavelength of λ=1200nm after IR excitation and has a decay time of 500µs.

[0066] For the two detection channels 42-1 and 42-2, InGaAs photodiodes 44-1 and 44-2 are used as photodiodes. These photodiodes are equipped with optical filters with different spectra to detect different spectral ranges.

[0067] In the first detection channel 42-1, the photodiode 44-1 is equipped with an optical bandpass filter with a center wavelength of 1030nm and an optical bandwidth of 20nm. The electronic amplifier circuit of the first detection channel 42-1 is adapted to the decay time of the first luminescence characteristic and has a bandwidth of 10kHz. For this purpose, the bandwidth of the first amplifier stage 50-1, consisting of operational amplifier 52-1 and parallel components, is set to 20kHz. Assuming the photodiode capacitance is 1nF, the gain-bandwidth product (GBW) of operational amplifier 52-1 is 20MHz, which can be achieved, for example, by resistor R1-1 = 2MΩ and capacitor C1-1 = 3.9pF. R1-1 = 2MΩ is equivalent to the transimpedance (gain) of the first amplifier stage 50-1. The input noise voltage density of operational amplifier 52-1 is 6. It can achieve an input reference noise current of approximately 63 pA.

[0068] In the second detection channel 42-2, the photodiode 44-2 is equipped 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 characteristic and has a bandwidth of 2 kHz. For this purpose, the bandwidth of the first amplifier stage 50-2, consisting of operational amplifier 52-2 and parallel components, is set to 4 kHz. Assuming the photodiode capacitance is 1 nF, the gain-bandwidth product (GBW) of operational amplifier 52-2 is 20 MHz, which can be achieved, for example, by resistor R1-2 = 18 MΩ and capacitor C1-2 = 2.2 pF. R1-1 = 18 MΩ is equivalent to the transimpedance (gain) of the first amplifier stage 50-2. The input noise voltage density of operational amplifier 52-2 is 6... It can achieve an input reference noise current of approximately 6.5 pA.

[0069] Amplifier modules 54-1 and 54-2 contain one or more amplifier stages that are adapted in terms of gain and bandwidth to the corresponding first amplifier stage 50-1 or 50-2 to optimize the driving of the ADCs 62-1 and 62-2 of the digital signal processing system 60. A better signal-to-noise ratio is achieved in the second detection channel compared to the case where the same electronics are used for both detection channels.

[0070] Example 2:

[0071] In another embodiment, the sensor device includes Figure 7 The detection device 84 shown in the figure includes, on the one hand, a detection device according to... Figure 2 The slow static detection channel 42-1 and its signal processing device, on the other hand, include according to Figure 3 or Figure 4 The system includes a fast, switchable detection channel 42-2 and a signal processing device 40. Specifically, two photodiodes 44-1 and 44-2, which are spectrally identical, can be used in the two detection channels. This allows for the advantageous adaptation of the fast detection channel to the emission characteristics to be measured.

[0072] For example, such a sensor device can be used to measure different emission characteristics with emission wavelengths of 1030-1060 nm and decay times of 50-500 µs. Both detection channels use InGaAs photodiodes and are optionally equipped with spectrally selective optical filters.

[0073] The first detection channel 42-1 is optimized for low-noise measurement of luminous intensity, and for example has the following characteristics: Figure 2 The static circuit has a bandwidth of 2kHz. Thanks to its excellent signal-to-noise ratio, this detection channel enables safe and reproducible measurements even at low light intensities.

[0074] The second detection channel 42-2 is optimized for the temporal behavior of light emission measurement, particularly the decay time of light emission. Since the same sensor device is used to measure light emission characteristics with different decay times, the second detection channel 42-2 is optimized, for example, according to... Figure 3 It is advantageously designed to have switchable bandwidth.

[0075] Specifically, electronic components with the following specifications can be used here, for example:

[0076] R1=4MΩ, C1=2pF

[0077] R2=600kΩ, C2=3pF

[0078] Photodiode capacitance = 1nF

[0079] Gain-bandwidth product GBW(operational amplifier 52-2) = 50MHz.

[0080] When switch S2 is open, a bandwidth of 10 kHz is generated (the bandwidth of the first amplifier stage is 20 kHz). In this state, the detection channel is used, for example, for emission characteristics with decay times in the range of 150 µs–500 µs. This measurement has a particularly high signal-to-noise ratio, thus allowing reliable measurement even of weak emission characteristics.

[0081] When switch S2 is closed, a bandwidth of 30 kHz is generated (the bandwidth of the first amplifier stage is 60 kHz). In this state, the detection channel is used, for example, for emission characteristics with a decay time in the range of 50 µs–150 µs. This allows for measurement of emission time behavior with exceptionally high time resolution. The transimpedance (gain) of the first amplifier stage 52-2 is 522 kΩ (R1 and R2 in parallel). An input reference noise current of approximately 500 pA can be achieved.

[0082] If the second detection channel 42-2 is used according to Figure 4 A multi-switching amplifier circuit can adapt the detector bandwidth to a wider range of emission decay times, or more precisely adapt the detector bandwidth to the decay time of the emission characteristics.

[0083] List of reference numerals

[0084] 10 banknotes

[0085] 12. Luminous characteristics

[0086] 20 Sensor Devices

[0087] 12 Transmission devices

[0088] 22. Excitement of radiation sources

[0089] 24. Excited radiation

[0090] 26 Detection Device

[0091] 28. Signal radiation

[0092] 30 Control and Analysis Units

[0093] 32 Detection channels with lower bandwidth

[0094] 34 Detection channels with high bandwidth

[0095] 40 Signal processing device

[0096] Detection channels 42, 42-1, and 42-2

[0097] 44, 44-1, 44-2 photodiodes

[0098] Amplifier modules 46, 46-1, and 46-2

[0099] 50, 50-1, 50-2 First Amplifier Stage

[0100] 52, 52-1, 52-2 Operational Amplifiers

[0101] Amplifier modules 54, 54-1, and 54-2

[0102] 60 Digital Signal Processing System

[0103] 62, 62-1, 62-2 Analog-to-Digital Converters

[0104] 64, 64' processor

[0105] 70 detection channels

[0106] 72 detection channels

[0107] 80 Detection Device

[0108] 82 Detection Device

[0109] 84 Detection Device

[0110] T transmission direction

Claims

1. A sensor device (20) for inspecting a planar data carrier (10) having luminescent characteristics (12), particularly a valuable document, said sensor device having ● An excitation radiation source (22) for exciting the luminescent feature (12), and ● Detection device (26), used to detect the luminous radiation (28) emitted by the luminous feature in response to the excitation of the luminous feature by the radiation through the excitation radiation source, and output a detection signal. Its features are, ● The detection device has at least two detection channels (42-1, 42-2), each detection channel having at least one photodiode (44) and a signal processing device (40) for processing the signals of the photodiodes (44-1, 44-2) and outputting corresponding detection signals, wherein the signal processing device has different bandwidths.

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

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

4. The 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, especially signal radiation in different spectral ranges within the infrared range.

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

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

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

8. The 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 amplifier stage can be configured by turning on or off the resistors and capacitors of the corresponding amplifier stage.

9. The sensor device (20) according to at least one of claims 1 to 8, characterized in that, The first detection channel (32) in the detection channel has a small bandwidth of 2kHz to 20kHz, and the second detection channel (34) in the detection channel has a large bandwidth of 20kHz to 200kHz.

10. The 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 2 to 20, preferably 5 to 10, and preferably includes boundary values ​​respectively.

11. The sensor device (20) according to at least one of claims 1 to 10, characterized in that, The detection channels (32, 34) have different gains, wherein the ratio of the larger gain to the smaller gain is 2 to 20, preferably 5 to 10, and preferably includes boundary values ​​respectively.

12. An inspection apparatus for inspecting a planar data carrier (10) equipped with a luminescent feature (12), particularly a valuable document, the inspection apparatus comprising a sensor device (20) according to any one of claims 1 to 11 and a transmission device (21), the transmission device introducing the planar data carrier (10) to be inspected into an interaction region or guiding it through an interaction region along a transmission path, wherein the luminescent feature (12) of the data carrier can be irradiated by the excitation radiation source (22) in the interaction region.

13. A method for inspecting a planar data carrier (10) equipped with a light-emitting feature (12) using a sensor device (20) according to any one of claims 1 to 11, wherein - Excitation radiation (24), particularly excitation radiation in the infrared spectral range, is applied to the luminescence characteristics (12) of the data carrier (10). - The detection device (26) collects the signal radiation (28) emitted in response to the luminescent feature (12), the detection device having at least two detection channels, each detection channel having at least one photodiode (44) and a signal processing device for processing the signal of the photodiode and outputting a corresponding detection signal, wherein, The signal processing device has different bandwidths, and - Determine the characterization properties and / or feature intensity of the luminescence feature based on the signals acquired by the at least two detection channels (32, 34).

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