Method for transmitting data of a functional device to a mobile evaluation device by means of a light signal

Abstract

The invention relates to a method for transmitting data (56) of a functional device (12) to a mobile evaluation device (14) by means of a light signal, wherein the operating state of the functional device (12) is signaled, on the basis of a control signal, so as to be visually detectable by emitting visible light (20) by means of a signal lamp (16), the control signal being modulated according to a specified modulation method (48), the emitted light is detected by a light detection unit (22) of the evaluation device (14), the light detection unit having light sensor elements (24) which are arranged in rows (26) and columns (28), detected light values of the light sensor elements are read successively in rows or successively in columns, and light values are evaluated by the evaluation device in order to determine the transmitted data. According to the invention, a frequency shift keying method using a plurality of modulation frequencies (f0, f1, f2, f3) is used, wherein, in the case of the light values (80) being read in rows, light value data relating to the light values of at least one column, as an evaluation column (74), is evaluated by the evaluation device in order to determine at least one of the modulation frequencies.

Description

[0001] Description

[0002] Method for transmitting data from a functional device to a mobile evaluation device using a light signal

[0003] Regardless of the grammatical gender of a particular term, persons with male, female or other gender identities are included.

[0004] The invention relates to a method for transmitting data from a functional device to a mobile evaluation device by means of a light signal, wherein the functional device provides a control signal for a signal lamp of the functional device, wherein an operating state of the functional device is visually indicated by the emission of visible light depending on the control signal, wherein the control signal is modulated according to the data to be transmitted according to a predetermined modulation method, so that the light signal is emitted by the signal lamp together with the light indicating the operating state, wherein the light emitted by the signal lamp is detected by a pixel-based digital light detection unit of the evaluation device, wherein the light detection unit has light sensor elements that are arranged in rows and columns.wherein the detected light values ​​of the light sensor elements are read out consecutively in rows or columns, wherein the light values ​​detected by the light sensor elements are evaluated by the evaluation device to determine the transmitted data, wherein the light values ​​detected by the light sensor elements are read out along a respective row or column of the light detection unit within a respective readout period that is less than half a period of a maximum modulation frequency used in the specified modulation method. The invention further relates to a system for transmitting data from a functional device of the system to a mobile evaluation device of the system by means of a light signal, wherein the functional device is configured to provide a control signal for a signal lamp of the functional device.to visually signal an operating state of the functional device depending on the control signal by emitting visible light, wherein the functional device is further configured to modulate the control signal according to the data to be transmitted according to a predetermined modulation method in order to emit the light signal together with the light signaling the operating state through the signal lamp, wherein the evaluation device has a pixel-based digital light detection unit for detecting the light emitted by the signal lamp, wherein the light detection unit has light sensor elements arranged in rows and columns, wherein the evaluation device is configured to read out light values ​​detected by the light sensor elements consecutively in rows or consecutively in columns and to evaluate the light values ​​detected by the light sensor elements in order to determine the transmitted data,wherein the evaluation device is further configured to read out the light values ​​detected by the light sensor elements along a respective row or column of the light detection unit within a respective readout period that is less than half a period of a maximum modulation frequency used in the specified modulation method. The invention further relates to a functional device of the system. Finally, the invention also relates to an evaluation device of the system.

[0005] Typical methods, systems, functional devices, and evaluation devices are extensively known in the prior art. Such methods and systems serve to easily obtain additional information from the functional device, beyond the function of the functional device's indicator light as a visually perceptible operating indicator, without requiring additional hardware for connecting and using, for example, a communication network for data exchange. Typically, the functional device has at least one indicator light that serves to visually display, for example, an optical status indicator or an operating indicator for a user. Such an indicator light can be, for example, a light-emitting diode (LED), a selective LED (SLD), or another suitable light source that enables the desired function.The functional device uses a control signal to operate the indicator light. This signal can be provided by a control unit of the functional device, such as a program-controlled computer unit or similar device. The indicator light can, for example, show that the functional device is activated or ready for operation, either to begin or perform its intended function.

[0006] Functional devices of this type are also widely known and frequently used in technical installations, such as production lines, particularly in the area of ​​automation components in electrical systems. A functional device can be, for example, a control unit for a programmable logic controller (PLC), a power supply unit, a network device, and / or the like.

[0007] A high degree of performance and complexity leads to a corresponding need for monitoring and maintenance. Although many functional devices already support remote maintenance and / or remote diagnostics, simpler functional devices, such as power supplies, are generally not integrated with this functionality. Nevertheless, such functional devices can be important, and in some cases critical, for the operation of an overall system. Therefore, there is a need to create a communication option for these functional devices as well. However, this should be achieved with as little additional effort as possible. In particular, the hardware requirements should be kept to a minimum, ideally requiring no additional hardware at all.

[0008] To improve the inspection and maintenance of the aforementioned functional devices, EP 4231 547 A1, for example, proposes creating a digital interface for the functional device. This interface, utilizing the indicator light, allows not only the user to see the operating status of the functional device but also the transmission of data from the functional device to a mobile evaluation unit. The indicator light's light signal is thus used not only as a visually perceptible operating indicator but also, through a modulation process, for an additional purpose: data transmission. Therefore, only the control signal for the indicator light is available for implementing this functionality. This control signal is modulated according to the data to be transmitted, using a predefined modulation process.The specified modulation method thus introduces the supplementary functionality that goes beyond the optical or visual signaling usually provided with the control signal.

[0009] In order to receive the data transmitted via the light signal as described above, a mobile evaluation device is provided. This mobile evaluation device enables the light emitted by the signal lamp to be detected using a pixel-based digital light detection unit. The evaluation device is therefore preferably a portable device that a user can easily carry. For example, the mobile evaluation device could be a portable device, in particular a mobile communication device, preferably a smartphone, or the like. The evaluation device includes the light detection unit, which could be, for example, a digital camera or the like. The light detection unit has sensor elements arranged in rows and columns, similar to a digital camera or the like.The light values ​​detected by the sensor elements are read out sequentially, either row by row or column by column. The evaluation unit analyzes these light values ​​to determine the transmitted data. This data is then available for further use within the evaluation unit. The transmitted data can include, for example, other operating states of the functional device, fault messages, parameter settings, and / or the like. The light sensor elements in the light detection unit are preferably arranged in a grid pattern. The light values ​​detected by the light sensor elements are read out along each row or column of the light detection unit within a specific readout period, which is less than half the period of one of the largest modulation frequencies used in the specified modulation method. This ensures reliable data transmission.In particular, this optical data transmission enables a standard camera of a user device, such as a mobile device, especially a smartphone, to provide the necessary pixel-based digital light capture unit. With such a camera or light capture unit, a so-called "rolling shutter effect" can then be used, resulting from the row-by-row or column-by-column reading of the light values ​​captured by the light sensor elements, to achieve suitable sampling rates that are significantly higher than the frequency of successive images in a video data stream of the camera.

[0010] However, it has become apparent that the use of the aforementioned technology requires suitable equipment, particularly the functional device for providing the light signal. EP 4231 547 A1 provides no information on this. For example, it is possible that the functional device, due to its design, is not suitable for use with all modulation frequencies. In such cases, reliable communication cannot be achieved.

[0011] The invention is based on the objective of improving a method, a system, a functional device and an evaluation device in such a way that the reliable transmission of the data can be verified.

[0012] The invention proposes a method, a system, a functional device and an evaluation device according to the independent claims as a solution.

[0013] Advantageous further training opportunities arise from the characteristics of the dependent requirements.

[0014] With regard to a generic method, the invention particularly proposes that a frequency shift keying (FSK) method with multiple modulation frequencies be used as the predetermined modulation method, wherein the detected light values ​​of the light sensor elements of all rows or all columns are read out exactly once in at least one readout cycle in order to form an image data set with a number of image pixels corresponding to the number of light sensor elements, wherein each image pixel is assigned light value data from exactly one respective light sensor element, wherein, in the case of the light values ​​read out row by row, light value data relating to the light values ​​of at least one column are evaluated by the evaluation device as an evaluation column in order to determine at least one of the modulation frequencies.or wherein, in the column-wise readout of light values, light value data for the light values ​​of at least one row are evaluated by the evaluation device as an evaluation row in order to determine at least one of the modulation frequencies.

[0015] With regard to a generic system, the invention particularly proposes that the functional device comprises a frequency-shift keying modulator and the evaluation device a frequency-shift keying demodulator, which are configured to use a frequency-shift keying method with multiple modulation frequencies as a predetermined modulation method, wherein the evaluation device is further configured to read out the detected light values ​​of the light sensor elements of all rows or all columns exactly once in at least one readout cycle in order to form an image data set with a number of image pixels corresponding to the number of light sensor elements, wherein the evaluation device is configured to assign light value data from exactly one respective light sensor element to each image pixel, and wherein the evaluation device is configured to evaluate light value data for the light values ​​of at least one column as an evaluation column from the light values ​​read out row by row.to determine at least one of the modulation frequencies, or, in the case of column-wise read-out light values, to evaluate light value data for the light values ​​of at least one row as an evaluation row by the evaluation device in order to determine at least one of the modulation frequencies.

[0016] With regard to a generic functional device, the invention proposes that the functional device is designed according to the invention.

[0017] With regard to an evaluation device of the generic type, the invention specifically proposes that the evaluation device be designed according to the invention.

[0018] The invention is based, among other things, on the idea that it is possible to test, using simple means, whether the functional device is suitable for using the specified modulation method. This can be achieved, for example, by setting up the functional device, carrying out the specified modulation method, and evaluating the light signals emitted by the signal lamp. If the modulation frequencies used by the specified modulation method can be verified using the evaluation device, it can be determined that the functional device is suitable for using the specified modulation method.For this purpose, a specific evaluation of the light values ​​detected by the light detection unit can be provided, in which the evaluation device reads the detected light values ​​of the light sensor elements of all rows or all columns exactly once in at least one readout cycle in order to create an image data set with a number of image pixels corresponding to the light sensor elements. The image data set therefore preferably contains either the light value data for the light sensor elements read out row by row or the light value data for the light sensor elements read out column by column. In a subsequent readout cycle, the light values ​​can be read out again accordingly to provide another image data set. This process can, in principle, be continued indefinitely.The modulation frequencies are preferably selected such that the light signals generated by the signal lamp are not visually perceived by a user. For example, the modulation frequencies can be higher than 1.2 kHz. Preferably, however, the modulation frequencies are lower than 5 kHz.

[0019] The subsequent function is preferably carried out based on at least one image data set by assigning each image pixel light value data from exactly one corresponding light sensor element. If the light values ​​were read out row by row, these light value data are assigned to them. The light value data for the light values ​​of at least one column, which forms a respective evaluation column, are evaluated to determine at least one of the modulation frequencies. The evaluation can, for example, take into account that the brightness values ​​of the light values ​​vary depending on the respective modulation frequency. This makes it possible to determine the reliable usability of the respective modulation frequency. Preferably, all used modulation frequencies are determined.

[0020] In principle, this can also be implemented for light values ​​read out column by column. If the light values ​​were read out column by column, light value data is also assigned to them. The light value data for the light values ​​of at least one row, which forms a respective evaluation row, are evaluated to determine at least one of the modulation frequencies. The further procedure corresponds to that described above. Preferably, the evaluation column comprises exactly one column. Correspondingly, the evaluation row preferably comprises exactly one row. In alternative embodiments, however, it can also be provided that the evaluation column comprises two or more columns or the evaluation row comprises two or more rows.

[0021] A frequency-shift keying (FSK) modulation method is used as the predefined modulation technique. The FSK has proven to be particularly advantageous and easy to implement for the application of the invention. At the same time, the FSK enables high reliability and / or interference immunity with regard to data transmission. Furthermore, the FSK allows for a comparatively high data rate, so that even a larger volume of data can be transmitted from the functional device to the evaluation device within a reasonable timeframe.

[0022] Frequency shift keying (FSK) preferably uses at least two different modulation frequencies. However, more than two modulation frequencies can also be used, for example, three, four, or even more. The modulation frequencies can, for example, be equidistant from each other.

[0023] Binary digital data is particularly advantageous. This allows for simple data processing and / or signal processing. This advanced technology can be combined particularly effectively with frequency-shift keying. For example, the functional device can be configured to emit the light signal according to a predefined data sequence.

[0024] The invention is not limited to the continuous emission of light by the signal lamp. It is equally applicable when the signal lamp emits light only intermittently or, for example, operates in a pulsed mode, such as to visually indicate a flashing state. It is understood that data transmission via the light signal only occurs when the signal lamp is actually emitting light. Furthermore, the invention is not limited to the signal lamp always emitting light of the same color or with the same luminous intensity. Depending on the operating status to be indicated, the color of the light emitted by the signal lamp can, of course, be changed, for example, from red to yellow or green, or vice versa. This is irrelevant to the function of the invention.Furthermore, the functional device can, of course, be provided with more than just a single signal light, for example, two signal lights, three signal lights, or the like. In this case, it can be provided that at least one of the signal lights of the functional device is used to emit the corresponding light signal. It can also be provided that two or even more signal lights are used to emit the light signal. Preferably, it can be provided that several signal lights are used together to emit the light signal, for example, by operating them synchronously. In addition, it is also possible that several signal lights are used to emit different light signals in parallel, corresponding to different data to be transmitted.

[0025] In particular, the invention can utilize the availability of a video data stream from a digital camera based on rolling shutter technology. A frequency response that decreases with frequency can result from the relationship between an exposure time and a transmission frequency. Therefore, with some evaluation devices, it may be advantageous to apply special methods for detecting the highest frequencies used. The invention allows the creation of a profile consisting of the period lengths of the individual detected modulation frequencies and a method for determining the highest frequency, i.e., the shortest period length. This profile can be used every time the evaluation device is used. For this purpose, the evaluation device's digital camera can capture the light signal transmitted by the functional device for analysis, as in normal operation; that is, no special training signal is required.

[0026] It is particularly advantageous if at least one indicator light can be directly controlled by a programmable control unit of the functional device. The invention can thus be easily implemented by adapting a computer program in the functional device. This also makes the invention particularly suitable for retrofitting existing functional devices.

[0027] The evaluation device is preferably a portable device that can be carried by a user. The evaluation device can be a digital camera connected to an evaluation unit. However, it can also be a tablet, a mobile phone, a laptop, or the like. The evaluation device includes a pixel-based digital light detection unit, which the user can position appropriately relative to the functional device so that the light detection unit can reliably detect the light emitted by the signal light. For example, the light detection unit can be positioned opposite the signal light. The user can achieve this positioning by appropriately positioning the evaluation device.

[0028] Preferably, the user positions the evaluation unit such that the light detection unit is located opposite the signal light. The distance between the signal light and the light detection unit can be a few centimeters or less. This significantly reduces interference with data transmission. Furthermore, it allows for data transmission with minimal technical effort. A particular advantage is that compliance with legal regulations, standards, and the like can be achieved with minimal effort. The invention thus enables cost-effective and reliable communication between the functional device and the evaluation unit. The respective process control can preferably be implemented by the evaluation unit.

[0029] According to a further development, it is proposed that the frequency-shift keying (FSK) demodulator of the evaluation unit be set depending on the at least one determined modulation frequency. This improves the signal processing of the evaluation unit. Preferably, the FSK demodulator can be set automatically. This makes it possible to use the evaluation unit with different functional devices without manual intervention.

[0030] Furthermore, it is proposed that, at least depending on the light value data contained in the evaluation column or row, a respective brightness oscillation and a reference value are determined. To determine the respective modulation frequency, the reference value is subtracted from the determined brightness oscillation to obtain a normalized oscillation. The normalized oscillation can be made available for further signal processing to determine the respective modulation oscillation. This allows for comparability with respect to an oscillation amplitude. The reference value can be, for example, a mean value, an RMS value, a peak value, or the like. The reference value can be, for example, a constant value. However, the reference value need not be constant; it can, for example, be at least partially variable over time.The reference value can preferably be determined from all light value data contained in the evaluation column or row. Preferably, the normalized oscillation is compared with a predetermined light reference value. The reference value is specifically defined such that only one normalized oscillation is further processed to determine the at least one modulation oscillation whose amplitude is greater than the reference value. The reference value can be chosen to ensure reliable communication. In particular, normalized oscillations with small amplitudes, which may fall within the range of a noise or interference signal, can be excluded from further consideration.

[0031] Furthermore, it is proposed that the evaluation device signal operational readiness based on the comparison. This would indicate to the user that communication is functioning reliably. The signaling could be implemented, for example, using a visual, audible, and / or haptic signal. The evaluation device could have a suitable output unit for this purpose.

[0032] Furthermore, it is proposed that a portion of the data for modulation in positive logic be provided by the functional device. Alternatively or additionally, it is proposed that a portion of the data for modulation in negative logic be provided by the functional device. This eliminates the need to convert the data into a specific format for modulation. Instead, the data can be used for transmission as provided by the functional device. Therefore, no corresponding signal processing is required.

[0033] According to a further development, it is proposed that successive data segments from the functional device be provided alternately in positive and negative logic. This has the advantage of allowing the use of as many modulation frequencies as possible. It has been shown that, for the communication according to the invention, the use of the highest modulation frequencies can be particularly critical. Depending on the sequence of data, therefore, as many modulation frequencies as possible, preferably all modulation frequencies, can appear in the light signal. This further improves the reliability of functional testing.

[0034] Furthermore, it is proposed that the functional device inserts a switching bit sequence between the respective data sections, at least when switching between a data section in positive logic and a subsequent data section in negative logic, or between a data section in negative logic and a subsequent data section in positive logic. The evaluation device can therefore easily detect when switching between positive and negative logic occurs. The switching bit sequence has at least one bit and is preferably chosen such that it does not appear in the data to be transmitted.

[0035] It is further proposed that the alternating bit sequence include at least one initialization bit. Of course, additional bits can also be provided, such as a stop bit, a bit indicating the type of logic, and / or the like. This enables or improves signal processing by the evaluation device.

[0036] Furthermore, it is proposed that the modulation method switches the modulation frequency from a first modulation frequency to a second modulation frequency at the transition between two consecutive bits. This makes it easy for the evaluation device to distinguish two consecutive bits as separate bits. Moreover, it is also possible to easily determine a clock rate for transmitting the data via the light signals. This can be advantageous for further signal processing by the evaluation device.

[0037] It is further proposed that the evaluation device be a smartphone. This makes it easy to provide a variety of inexpensive evaluation devices and make them usable for the invention.

[0038] It is particularly advantageous if the evaluation device is a smartphone or tablet, especially if it is a smartphone itself, wherein the smartphone or tablet has a camera as a light-sensing unit that provides the captured light values ​​in the form of image data, and wherein an application is installed on the smartphone or tablet that evaluates the image data provided by the camera in order to determine the transmitted data. In this way, it is possible to use a standard smartphone or tablet as an evaluation unit.

[0039] Of course, this further training can also be carried out using a suitably equipped tablet or laptop, possibly with the use of a webcam. Preferably, the image data consists of image data sets. Therefore, no separate evaluation devices need to be designed for the use of the invention. Rather, a standard smartphone can be easily enabled to perform the functions of the evaluation device in conjunction with the camera as a light detection unit by installing an app. The advantages and effects stated for the method according to the invention also apply equally to the system according to the invention, the functional device according to the invention, and the evaluation unit according to the invention, and vice versa. In particular, method features can therefore also be formulated as device features, or vice versa.

[0040] The embodiments described below are preferred embodiments of the invention. The features and combinations of features specified above in the description, as well as those mentioned in the following description of embodiments and / or shown individually in the figures, are not only usable in the combinations specified, but also in other combinations. Thus, embodiments are also encompassed by the invention or are considered disclosed that are not explicitly shown and explained in the figures, but can be derived and generated from the described embodiments by separate combinations of features.The features, functions, and / or effects illustrated by the exemplary embodiments can each, considered independently, represent individual features, functions, and / or effects of the invention, each of which further develops the invention independently. Therefore, the exemplary embodiments are intended to include combinations other than those described in the embodiments. Furthermore, the described embodiments can also be supplemented by additional features, functions, and / or effects of the invention already described.

[0041] In the figures, the same reference symbols denote the same features or functions.

[0042] This shows:

[0043] FIG 1 shows a schematic block diagram of a system for transmitting data from a power supply to a smartphone using a light signal.

[0044] FIG 2 shows a schematic block representation of a section of the smartphone according to FIG 1 with a camera for capturing and demodulating the data,

[0045] FIG 3 a schematic signal representation of a video data stream provided by the camera, FIG 4 a schematic signal representation for a 4-FSK modulation method for transmitting the data through the system according to FIG 1,

[0046] FIG 5 is a schematic diagram representation of a transmission characteristic, which in particular takes into account properties of the camera of the smartphone according to FIG 2, FIG 6 is a schematic representation of an image with light values ​​captured by the camera according to FIG 2, which are read out line by line,

[0047] FIG 7 shows a schematic diagram representation of light values ​​of the image according to FIG 2, as detected by a readout column, and

[0048] FIG 8 shows a schematic diagram representation of the light values ​​corrected by a reference value according to FIG 7.

[0049] FIG 1 shows a schematic block diagram of a system 10 for transmitting data 56 (FIG 4) from a power supply 12, as a functional device of the system 10, to a smartphone 14, as a mobile evaluation device of the system 10, by means of a light signal. The power supply 12 is configured to provide a control signal for a signal lamp 16 of the power supply 12. The signal lamp 16 is formed by a light-emitting diode (LED) which is electrically connected to a control module 30 of the power supply 12 via a control line 18. The control module 30 can determine or specify one or more operating states of the power supply 12 and, depending on the current operating state, outputs a corresponding control signal to the control line 18 to visually indicate the respective operating state of the power supply 12 by emitting visible light 20.In the present embodiment, the operating state is determined by an active state, whereby the power supply 12 provides an electrical power supply for another device (not shown) as intended. The light 20 is visually perceptible to a user (not shown) with their eyes, so that they can immediately recognize that the power supply 12 is in the activated operating state to provide the desired power supply.

[0050] The power supply 12 is, in this case, a component of a control system (not shown) for a production plant. For monitoring and maintenance of the plant, it is particularly desirable to have access to additional data from the power supply 12, such as its current electrical power, current, voltage, data relating to protective functions that limit or prevent overloading, temperature, and / or similar information. In the prior art, it is common practice to connect the power supply 12 to a communication network so that the desired data can be queried via this network. For this purpose, it is common practice in the prior art to provide the power supply 12 with appropriate additional hardware and software to achieve the desired functionality.However, this is complex and expensive, and particularly inefficient for systems that have a large number of, for example, smaller functional devices.

[0051] To reduce this disadvantage, the light 20 emitted by the signal lamp 16 can be used to transmit the data 56 to the smartphone 14. This eliminates the need for separate hardware in the power supply 12. Instead, the control signal can be modulated according to a predefined modulation method 48, corresponding to the data 56 to be transmitted, in order to emit the light signal together with the light 20 indicating the operating state through the signal lamp 16. This emitted light 20 can be detected by the smartphone 14, specifically by its camera 22. It can be noted that the camera 22 is typically designed as a digital camera in the form of a pixel-based digital light detection unit, which has light sensor elements 24 arranged in rows 26 and columns 28, as can be seen in FIG. 2.

[0052] The smartphone 14 has a control unit 32, which includes, among other things, a program-controlled computer unit (not shown). The control unit 32 is communicatively coupled to the camera 22 and is designed to read out the light values ​​detected by the light sensor elements 24 consecutively, either row by row or column by column. Once all rows 26 or columns 28 have been read consecutively, this process can be repeated cyclically, so that the detected light values ​​are provided in the form of a video data stream 46 of images 42 with image data 44, which includes, among other things, the transmitted data 56. The control unit 32 evaluates the detected light values ​​and determines the transmitted data 56.

[0053] The system 10 is designed such that the light values ​​detected by the light sensor elements 24 are read out along a respective row 26 or column 28 of the light detection unit 24 within a respective readout period that is less than half a period of the largest modulation frequencies f0, f1, f2, f3 used in the specified modulation method 48. This is further explained with reference to FIG. 4. In the present embodiment, the power supply 12 is configured to use the modulation frequencies f0, f1, f2, f3 of the specified modulation method 48 within the framework of a frequency shift keying (FSK) method, which are on the one hand greater than 1.2 kHz and on the other hand less than 5 kHz. This is therefore a 4-FSK modulation method.This selection allows the modulation frequencies fO, f1, f2, f3 used by the specified modulation method 48 to be greater than 1.2 kHz, so that a user cannot perceive any light fluctuations with their eye. This has the advantage that, from the user's perspective, the signal light 16 remains continuously illuminated when the respective operating status is indicated, and flickering due to modulation is avoided. The visual signaling function of the signal light 16 can thus be maintained essentially undisturbed.

[0054] At the same time, the invention makes it possible to emit light signals with the light 20, which can then be used to transmit the data 56. For this purpose, the modulation frequencies are provided to be less than 5 kHz. It is taken into account that the camera 22 is a pixel-based digital camera in which the light sensor elements 24 are arranged in the rows 26 and columns 28. Depending on the design of the smartphone 14, the rows 26 may be read either cyclically, row by row, or cyclically, column by column. However, this is not relevant to the function of the invention. By utilizing the rolling shutter effect, which is employed in the smartphone 14 due to this signal processing by the camera 22, it is possible to determine the data 56 from the light signals.

[0055] As can also be seen from FIG 1, the control module 30 has a frequency shift modulator 34 which receives the data 56 from a data storage 36 of the control module 30 and modulates it onto the control signal according to the specified modulation method 48, so that the modulated control signal is output to the signal lamp 16 via the control line 18.

[0056] The control unit 32 is also connected to a frequency-shift keying (FSK) demodulator 38, which demodulates the detected light signal. The FSK demodulator 38 delivers the data 56 determined in this way to the processing unit 40 of the smartphone 14, so that it can be further processed as needed. This further processing can, for example, consist of transmitting the data 56 to a remote control center via a mobile network. It can also be provided that the data 56 can be selected and displayed visually on a screen of the smartphone 14.

[0057] FIG. 2 shows a schematic block diagram of the camera 22 with the light sensor elements 24, which are arranged in rows 26 and columns 28. The light sensor elements 24 are electrically connected to the control unit 32 of the smartphone 14 via a corresponding electrical matrix circuit (not shown). The control unit 32 is configured to read the corresponding light values. The control unit 32 includes a program-controlled computing unit (not shown).

[0058] FIG. 3 shows a schematic signal representation of the video data stream 46 provided by the camera 22. FIG. 3 shows that the video data stream 46 comprises successive images 42, each image 42 containing corresponding image data 44. The image data 44 correspond to the respective light values ​​detected by the light sensor elements 24. Thus, for example, a corresponding light value from a respective light sensor element 24 can be assigned to each pixel of the image 42. In the present embodiment, the light values ​​are provided as digital image data 44.

[0059] In the present embodiment, a frequency-shift keying (FSK) modulation method 48 is used. FIG. 4 shows a schematic signal representation for a modulation method used in the present embodiment, which is a 4-FSK modulation method and serves to transmit the data 56 through the system 10 according to FIG. 1. As can be seen from FIG. 4, the FSK modulation method uses the modulation frequencies f0, f1, f2, f3, which are in an integer ratio to each other. Furthermore, FIG. 4 shows that each bit of the data 56 is assigned two different modulation frequencies f0, f1, f2, f3 by means of the specified modulation method 48, which serve to transmit the respective bit. A graph 58 indicates a frequency response resulting from a data sequence according to the data 56 shown in FIG. 4.As can be seen from graph 58, additional bits are added to the data stream 56 as part of the modulation procedure 48: an initialization bit 60, a start bit 62, a bit 64 to indicate positive logic, a stop bit 66, and a bit 68 to indicate negative logic. The corresponding modulation frequencies f0, f1, f2, and f3 are then assigned to the data sequence prepared in this way, according to graph 58, as part of the modulation procedure 48. This signal is then superimposed on the control signal on the control line 18, so that it can be emitted as a light signal by the signal lamp 16 with the light 20.

[0060] As can be seen in FIG. 4, the data stream begins with an initialization bit 60, followed by a start bit 62. The initialization bit 60 is always assigned the modulation frequency f0. The initialization bit 60 is followed by a start bit 62, which is always assigned the modulation frequency f2. This allows a receiver, in this case the smartphone 14, to recognize the beginning of a data sequence. Next in the data stream is the transmission of bit 64 for the positive logic indication, which transmits the modulation frequency f1. This is followed by the transmission of 10100 data bits, with the respective modulation frequencies being transmitted as shown in graph 58. To prevent the transmission of the start of a signal when the last bit, which is transmitted by the modulation frequency f0, is sent, the modulation frequency f3 is subsequently transmitted as the stop bit 66.

[0061] This is followed by the retransmission of the initialization bit 60 and the start bit 62, so that the receiver, i.e., the smartphone 14, can see that a new data sequence is about to follow. After the start bit 62, bit 68 for the negative logic is transmitted first, using the modulation frequency f3. This is followed by the transmission of a data sequence 10001, for which the modulation frequencies are transmitted according to graph 58. Finally, this transmission ends with the stop bit 66, which in this case is assigned the modulation frequency f2. This is followed by another transmission of the initialization bit 60 and the start bit 62, as previously explained, after which another bit sequence can be transmitted, which, however, is not shown in FIG. 4.

[0062] As can be seen in FIG. 4, the modulation method 48 changes the modulation frequency from a first modulation frequency to a second modulation frequency at a transition between two consecutive bits of the data 56. This makes it easily recognizable at the receiver that a new bit is being sent.

[0063] FIG. 5 shows a schematic diagram of a transmission characteristic, which takes into account, in particular, the properties of the camera 22 of the smartphone 14 according to FIG. 2. In FIG. 5, an abscissa is assigned to the product of an exposure time and a frequency, and an ordinate is assigned to a normalized amplitude of light 20 captured by the camera 22. A graph 50 shows the corresponding course of a resulting transmission characteristic. As can be seen from FIG. 5, local minima 54 occur at the values ​​1, 2, 3, and 4. In contrast, local maxima 52 occur at the values ​​0.5, 1.5, 2.5, and 3.5. In the present embodiment, the modulation frequencies f0, f1, f2, and f3 are selected in the ranges of the respective local maxima 52. This allows for particularly favorable signal transmission with high reliability and interference immunity.This also allows the modulation frequencies fO, f 1 , f2, f3 to be spaced apart from each other by the areas of the local minima 54 of the transmission characteristic.

[0064] In an alternative embodiment, it can be provided that each bit of the data 56 is assigned two different modulation frequencies f0, f1, f2, f3 by means of the specified modulation method 48, which serve to transmit the respective bit. That is, in this embodiment, the modulation frequency f0, f1, f2, f3 changes during the transmission of each bit.

[0065] The following configuration is provided for commissioning the system 10. The control module 30 of the power supply 12 is programmed to output the data 56 as light signals via the signal lamp 16 according to the procedure previously described with reference to FIG. 4. The light 20 containing the light signals is captured by the digital camera 22 of the smartphone 14. An image 70 is obtained by reading the light values ​​80 line by line from the digital camera 22. FIG. 6 shows a schematic representation of the image 70. As can be seen from FIG. 6, the image 70 contains horizontal stripes or lines 72 of different brightness. Consequently, a brightness oscillation is obtained perpendicular to the lines 72.

[0066] The readout process creates an image data set of image 70 with a number of image pixels corresponding to the light sensor elements 24. The recorded light values ​​80 of the light sensor elements 24 of all lines 72 are read out exactly once in a readout cycle. Each image pixel is assigned light value data from exactly one respective light sensor element 24.

[0067] Next, an evaluation column 74 is determined, which is arranged transversely to the rows 72. The evaluation column 74 detects one light sensor element 24 of each row 72. FIG 7 shows a schematic diagram representation of the light values ​​80 of the image 70 according to FIG 6, detected by a readout column 74. In the diagram representation according to FIG 7, an abscissa is assigned to the light sensor elements 24 of the evaluation column 74, whereas an ordinate is assigned to a brightness. A graph 76 shows the brightness oscillation.

[0068] Based on the light value data from the light sensor elements 24 recorded by the evaluation column 74, a mean value can be determined as a reference value. In a further processing step, the reference value is subtracted from the light value data. This results in a schematic diagram representation according to FIG. 8, in which the light value data according to FIG. 7 are corrected by a reference value. A normalized oscillation is thus determined, as shown in FIG. 8 with a graph 78. A corresponding modulation frequency fO, f1, f2, f3 can then be determined from this oscillation. The procedure can be repeated to determine further modulation frequencies fO, f1, f2, f3, preferably to determine all modulation frequencies fO, f1, f2, f3.

[0069] In this context, switching between positive and negative logic can prove advantageous. If the data 56 contained a long sequence of zeros or ones, it might not be possible to determine all modulation frequencies f0, f1, f2, f3. Switching the logic can reduce or eliminate this problem.

[0070] The normalized oscillation can further be compared with a predetermined light reference value. The light reference value is chosen such that the amplitude of the normalized oscillation can be reliably distinguished from noise. If an amplitude is smaller than the light reference value, no further signal processing is required. Preferably, therefore, only those normalized oscillations whose amplitudes are at least partially larger than the light reference value are processed further to determine the modulation frequencies f0, f1, f2, f3.

[0071] If it turns out that not all modulation frequencies fO, f1, f2, f3 can be determined, the smartphone 14 can output a corresponding signal. This allows the user to adjust the system 10, for example by restricting the frequency range for the modulation frequencies fO, f1, f2, f3 to a smaller range, so that all modulation frequencies fO, f1, f2, f3 can be determined.

[0072] In a further embodiment, if the reading is performed column by column, the procedure is adapted accordingly. These embodiments serve solely to illustrate the invention and are not intended to limit it.

[0073] Reference symbol list

[0074] 10 System

[0075] 12 Power supply

[0076] 14 Smartphones

[0077] 16 Signal light

[0078] 18 Control line

[0079] 20 lights

[0080] 22 Digital camera

[0081] 24 light sensor elements

[0082] Line 26

[0083] Column 28

[0084] 30 Control module

[0085] 32 Control unit

[0086] 34 Frequency Shift Modulator

[0087] 36 data storage devices

[0088] 38 Frequency Shift Demodulator

[0089] 40 processing units

[0090] 42nd image

[0091] 44 image data

[0092] 46 Video data stream

[0093] 48 Modulation methods

[0094] 50 Graph

[0095] 52 local maximum

[0096] 54 local minimum

[0097] 56 data

[0098] 58 Graph

[0099] 60 initialization bits

[0100] 62 start bits

[0101] 64 positive logic

[0102] 66 stop bits

[0103] 68 negative logic

[0104] 70 images

[0105] 72 lines

[0106] 74 Evaluation column

[0107] 76 Graph 78 Graph

[0108] 80 light value fO Modulation frequency f1 Modulation frequency f2 Modulation frequency f3 Modulation frequency

Claims

Patent claims 1. Method for transmitting data (56) from a functional device (12) to a mobile evaluation device (14) by means of a light signal, wherein the functional device (12) provides a control signal for a signal lamp (16) of the functional device (12), wherein an operating state of the functional device (12) is visually indicated by the emission of visible light (20) depending on the control signal, wherein the control signal is modulated according to the data (56) to be transmitted according to a predetermined modulation method (48), such that the light signal is emitted by the signal lamp (16) together with the light (20) indicating the operating state, wherein the light (20) emitted by the signal lamp (16) is detected by a pixel-based digital light detection unit (22) of the evaluation device (14), wherein the light detection unit (22) has light sensor elements (24) arranged in rows (26) and columns (28),wherein the detected light values ​​(80) of the light sensor elements (24) are read out consecutively in rows or consecutively in columns, wherein the light values ​​(80) detected by the light sensor elements (24) are evaluated by the evaluation device (14) in order to determine the transmitted data (56), characterized in that a frequency shift keying method with several modulation frequencies (f0, f1, f2, f3) is used as the specified modulation method (48), wherein the detected light values ​​(80) of the light sensor elements (24) of all rows (26) or all columns (28) are read out exactly once in at least one readout cycle in order to form an image data set with a number of image pixels corresponding to the number of light sensor elements (24), wherein each image pixel is assigned light value data from exactly one respective light sensor element (24),wherein, in the case of light values ​​(80) read out row by row, light value data for the light values ​​(80) of at least one column are evaluated as evaluation column (74) by the evaluation device (14) in order to determine at least one of the modulation frequencies (fO, f1, f2, f3), or wherein, in the case of light values ​​(80) read out column by column, light value data for the light values ​​(80) of at least one row are evaluated as evaluation row by the evaluation device (14) in order to determine at least one of the modulation frequencies (fO, f1, f2, f3).

2. Method according to claim 1, characterized in that all modulation frequencies (fO, f 1 , f2, f3) are determined.

3. Method according to one of the preceding claims, characterized in that a frequency shift demodulator (38) of the evaluation device (14) is set depending on the at least one determined modulation frequency (fO, f1, f2, f3).

4. Method according to one of the preceding claims, characterized in that at least depending on the light value data contained in the evaluation column (74) or the evaluation row, a respective brightness oscillation and a reference value are determined, wherein to determine the respective modulation frequency (fO, f1, f2, f3) the reference value is subtracted from the determined brightness oscillation in order to obtain a normalized oscillation.

5. Method according to claim 4, characterized in that the normalized oscillation is compared with a predetermined light reference value.

6. Method according to claim 5, characterized in that, depending on the comparison, a functional readiness is signaled by the evaluation device (14).

7. Method according to one of the preceding claims, characterized in that a part of the data (56) is provided by the functional device (12) for modulation in positive logic.

8. Method according to one of the preceding claims, characterized in that a part of the data (56) is provided by the functional device (12) for modulation in negative logic.

9. Method according to one of the preceding claims, characterized in that successive data sections of the data (56) are provided alternately in positive and negative logic by the functional device (12).

10. Method according to claim 9, characterized in that the functional device inserts a switching bit sequence (60, 62, 66) between the respective data sections at least when switching between a data section in positive logic and a subsequent data section in negative logic or when switching between a data section in negative logic and a subsequent data section in positive logic.

11. Method according to claim 10, characterized in that the alternating bit sequence has at least one initialization bit (60).

12. System (10) for transmitting data (56) from a functional device (12) of the system (10) to a mobile evaluation device (14) of the system (10) by means of a light signal, wherein the functional device (12) is configured to provide a control signal for a signal lamp (16) of the functional device (12) in order to visually indicate an operating state of the functional device (12) depending on the control signal by emitting visible light (20), wherein the functional device (12) is further configured to modulate the control signal according to the data (56) to be transmitted according to a predetermined modulation method (48) in order to emit the light signal together with the light (20) indicating the operating state by means of the signal lamp (16), wherein the evaluation device (14) has a pixel-based digital light detection unit (22) for detecting the light (20) emitted by the signal lamp (16), wherein the light detection unit (22) light sensor elements (24)which are arranged in rows (26) and columns (28), wherein the evaluation device (14) is configured to read out light values ​​(80) detected by the light sensor elements (24) consecutively in rows or consecutively in columns and to evaluate the light values ​​(80) detected by the light sensor elements (24) in order to determine the transmitted data (56), characterized in that the functional device (12) has a frequency-shift keying modulator (34) and the evaluation device (14) has a frequency-shift keying demodulator (38), which are configured to use a frequency-shift keying method with several modulation frequencies (f0, f1, f2, f3) as a predetermined modulation method (48), wherein the evaluation device (14) is further configured to read out the detected light values ​​(80) of the light sensor elements (24) of all rows (26) or all columns (28) exactly once in at least one readout cycle,to form an image data set with a number of image pixels corresponding to the light sensor elements (24), wherein the evaluation device (14) is configured to assign light value data from exactly one respective light sensor element (24) to each image pixel, wherein the evaluation device (14) is configured to evaluate, in the case of light values ​​(80) read out row by row, light value data for the light values ​​(80) of at least one column as an evaluation column (74) by the evaluation device (14) in order to determine at least one of the modulation frequencies (fO, f1, f2, f3), or, in the case of light values ​​(80) read out column by column, to evaluate, in the case of light values ​​(80) read out column by column, light value data for the light values ​​(80) of at least one row as an evaluation row by the evaluation device (14) in order to determine at least one of the modulation frequencies (fO, f1, f2, f3).

13. Functional device (12) of the system (10) according to claim 12.

14. Evaluation device (14) of the system (10) according to claim 12.

15. Evaluation device according to claim 14, characterized by a smartphone or a tablet having a camera as a light detection unit (22) which provides the detected light values ​​in the form of a video data stream (46) of images (42) with image data (44), wherein an application is installed on the smartphone (14) which evaluates the image data (44) provided by the camera (22) in order to determine the transmitted data (56).

Images