Optoelectronic receiver, optoelectronic sensor, use and method for distance measurement using the time-of-flight method

Abstract

The invention relates to an optoelectronic receiver, in particular for distance measurement using time-of-flight methods, comprising at least one signal generator for generating at least one diagnostic signal, a pixel array with at least one, in particular differential, receiving pixel and with at least one reference pixel, wherein the pixel array is configured to generate and output a received signal based on received light received by means of the receiving pixel and / or a reference signal by reading the reference pixel. The optoelectronic receiver further comprises at least one processing unit for signal processing and at least one connection unit, which is connected to the pixel array, the signal generator and the processing unit and is configured to selectively couple either the pixel array or the signal generator to the processing unit.so that either the received signal and / or the reference signal or the diagnostic signal can be selectively fed into the processing unit for signal processing, wherein the connection unit is configured to couple the signal generator with the processing unit at specific time intervals, and preferably during, in particular at the end, of each illumination phase of the distance measurement and / or between each illumination phase of the distance measurement, in order to feed the diagnostic signal into the processing unit for signal processing for a first functional test, in particular for recording diagnostic data.

Description

[0001] The invention relates to an optoelectronic receiver, an optoelectronic sensor, a use and a method, in particular for distance measurement using (light) time-of-flight methods.

[0002] In conventional optoelectronic receivers and sensors, components are often redundantly designed to ensure the safest possible operation. The terms "safe" or "safety" used here can be understood in the sense of specific safety standards, such as IEC 61508, ISO 13849, or IEC 62998. However, redundancy (i.e., the use of two optoelectronic receivers or redundant structures within the receiver) can have disadvantages, such as a larger chip size, a larger device size, higher power consumption, longer processing time, and / or higher costs.

[0003] Monitoring and testing the components of an optoelectronic receiver, ideally during operation, can improve the receiver's performance, particularly with regard to its functional safety. Specifically, for safety-critical applications, achieving a certain level of diagnostic coverage through functional testing can be beneficial or even necessary. In other words, appropriate functional tests should enable the reliable detection of specific internal faults. This can be especially important when optoelectronic receiver components are not redundant.

[0004] The invention is based on the objective of improving the efficiency and performance of an optoelectronic receiver, particularly with regard to its functional safety.

[0005] To solve the problem, an optoelectronic receiver with the features of claim 1 is provided.

[0006] The optoelectronic receiver according to the invention, in particular for distance measurement using (light) time-of-flight methods, comprises at least one signal generator for generating at least one diagnostic signal and a pixel array with at least one receiving pixel and with at least one reference pixel, wherein the pixel array is configured to generate and output a received signal based on received light received by means of the receiving pixel and / or a reference signal by reading out the reference pixel.The optoelectronic receiver further comprises at least one processing unit for signal processing and at least one connection unit, which is connected to the pixel array, the signal generator, and the processing unit and is configured to selectively couple either the pixel array or the signal generator to the processing unit, so that either the received signal and / or the reference signal or the diagnostic signal can be selectively fed into the processing unit for signal processing. The connection unit is configured to couple the signal generator to the processing unit at (pre-)defined time intervals in order to feed the diagnostic signal into the processing unit for signal processing for an initial functional test, in particular for recording diagnostic data.

[0007] Preferably, the connection unit is configured to couple the at least one signal generator with the processing unit (at predetermined times) during, and in particular at the end of, each illumination phase of the distance measurement and / or between each illumination phase of the distance measurement, for the first functional test. Preferably, the connection unit is configured to couple the at least one signal generator with the processing unit at the same acquisition rate as the distance measurement for the first functional test.

[0008] In other words, the invention is based on the idea of ​​providing a connection unit in the optoelectronic receiver, or utilizing an existing connection unit, by means of which a coupling can be established either between the processing unit and the pixel array or between the processing unit and the at least one signal generator. In other words, the connection unit allows the received signal and / or the reference signal to be replaced with the diagnostic signal for subsequent signal processing, particularly in relation to a control signal, for an (initial) functional test independent of external influences. Furthermore, the possibility arises of implementing further (or alternative) functional tests using the at least one reference pixel. This approach can allow for the detection of errors in the optoelectronic receiver, and in particular in the processing unit and also in other components, e.g.In an (optional) downstream data preprocessing unit, the optoelectronic receiver can detect faults during operation and improve its functional safety without requiring redundant hardware structures. For example, a warning signal can be issued upon fault detection. This implementation of the optoelectronic receiver can be more efficient with regard to (additional) circuitry, power consumption, software requirements, processing time, and other factors. Overall, this can increase the efficiency and / or performance of the optoelectronic receiver, particularly with respect to its functional safety. Preferably, this enables the use of (conventional) optoelectronic receivers for safety applications.

[0009] Preferably, for the initial functional test, several sets of diagnostic data are recorded between or during each illumination phase of the distance measurement. Preferably, the at least one signal generator is configured to use different settings for each recording of a diagnostic data set. For example, the amplitude of the diagnostic signal can be varied for the start and / or end of a diagnostic run, and in particular, selected according to the specific application.

[0010] Preferably, at least one of the receiving pixels can be a differential receiving pixel. In other words, it is possible to test the functionality of an optoelectronic receiver with at least one differential receiving pixel during operation.

[0011] The (differential) receive pixel can, for example, comprise at least two storage elements (i.e., charge storage devices, charge wells) which can be addressed separately in time and, depending on the phase of the distance measurement, can collect and store received light (e.g., as an electrical charge) at different times. The storage elements can include capacitors. The timing of the transmission of the transmitted light and the timing of the activation of the storage elements can be synchronized. The time offset can be learned and corrected at a later point in the processing chain to enable more accurate measurement. The storage elements can then be read out, simultaneously or at different times, to generate the (differential) receive signal.This design of the receiving pixel can reduce the susceptibility of the optoelectronic receiver to ambient light, reduce noise in distance measurement, and improve the dynamic range of the optoelectronic receiver.

[0012] For example, at least one (differential) receiving pixel can comprise a first and a second storage element. The first storage element can be configured to collect and store received light as an electrical charge (i.e., the amount of charge corresponding to the reflected or remitted pulses of the transmitted light) for the duration of each emitted pulse of the transmitted light, i.e., from the moment the transmitted light is emitted until the moment a subsequent pulse of the transmitted light is emitted. The first signal component of the received signal can then be generated by reading the first storage element, and the second signal component of the received signal can be generated by reading the second storage element.The first and / or the second signal component of the received signal can optionally be temporarily stored in an (analog) memory and then output together.

[0013] The acquisition rate for distance measurement can range from 10 Hz to 100 Hz. Multiple individual measurements, such as nine, can be combined for distance measurement. For example, at an acquisition rate of 30 Hz, a total of 30 * 9 = 270 individual measurements are performed per second. For instance, modulated light can be emitted, meaning that a multitude of pulses of light can be emitted for each individual measurement. The illumination phase of the distance measurement can encompass all processes necessary to generate the measured values, which ultimately result in a measured distance value.

[0014] The diagnostic signal can be a current signal or a voltage signal. Accordingly, the signal generator can be a current generator or a voltage generator. Preferably, the signal generator includes a (programmable) voltage generator for generating a variable voltage signal. The signal generator can include a digital-to-analog converter (DAC).

[0015] The optoelectronic receiver can receive transmitted light reflected or remitted (i.e., diffusely reflected) from a detection area (especially from objects within the detection area) and generate the received signal based on this received light using at least one receiving pixel. The received signal can be a differential signal comprising a first signal component and a second signal component, each output via a separate output and / or transmitted via separate lines.

[0016] The transmitted light can be generated by a light transmitter coupled to and / or controlled by the optoelectronic receiver and emitted into the detection area.

[0017] The optoelectronic receiver can, for example, include a controller, such as a microprocessor, a programmable logic controller (PLC), or a field-programmable gate array (FPGA), configured to control the optoelectronic receiver, and in particular the interconnect, and preferably also other devices, such as a light source and / or at least a reference illumination unit, in order to perform the initial functional test (and / or other functional tests). The controller can, for example, be pre-installed in the optoelectronic receiver to control general functions of the pixel array and / or the processing unit (and / or other devices, such as a light source and / or a reference illumination unit).In other words, an existing controller, typically used for other purposes, can be reused for the implementation of the first functional test (and / or other functional tests) of the optoelectronic receiver, so that no additional controller needs to be provided for the implementation of the first functional test (and / or other functional tests).

[0018] The optoelectronic receiver can also contain multiple signal generators, for example, two, three, four, or more. For instance, at least one signal generator can be provided for each column and / or row of the pixel array. Each signal generator can be programmed differently and, for example, output a different diagnostic signal.

[0019] According to one embodiment, the at least one reference pixel comprises at least one dark pixel, wherein the pixel array is configured to generate and output a dark signal by reading the dark pixel for a second functional test, in particular for recording dark signal data, and wherein the connection unit is configured to couple the pixel array to the processing unit at (pre-)determined time intervals in order to feed the dark signal into the processing unit for signal processing during the second functional test, in particular for recording the dark signal data. In other words, the reference signal can include the dark signal; in particular, the reference signal can be the dark signal.Preferably, the interconnection unit is configured to couple the pixel array with the processing unit (at predetermined times) during and / or between each illumination phase of the distance measurement for the second functional test. Preferably, the interconnection unit is configured to couple the pixel array with the processing unit at the same acquisition rate as the distance measurement for the second functional test. The dark pixel can, for example, be a pixel located outside an illumination area and / or covered by a metallization layer. Alternatively, it can, for example, be a receiving pixel that is less sensitive to receiving light.The reduced sensitivity can be achieved, for example, by a mechanical cover, an aperture, at least one optical filter, a restriction of the illumination area via the lens design, and / or by controlling the pixel (e.g., by reducing the integration time, changing the quantum efficiency or readout efficiency, varying the supply voltage, or other means). The dark signal can be a (temperature-dependent) signal with a very low signal amplitude, particularly one close to zero, which provides a reference point that is ideally largely independent of external influences. Preferably, for the second functional test, several sets of dark signal data are recorded between or during each illumination phase of the distance measurement.Preferably, the pixel array is configured to use different settings, in particular different integration times for reading the dark pixel, for each acquisition of a dark signal data set. This second functional test allows for the detection of faults in the optoelectronic receiver, and especially in both the pixel array and downstream components such as the interconnect unit, the processing unit, and / or an (optional) data preprocessing unit, during operation of the optoelectronic receiver, thus further improving its functional reliability. At least one dark pixel can be largely shielded from external influences (e.g., transmitted light from other sensors and / or ambient light) during the second functional test.The second functional test can therefore be used to verify whether the optoelectronic receiver is functioning correctly under largely excluded external influences.

[0020] According to a further embodiment, the at least one reference pixel comprises at least one reference receiving pixel, which receives reference light and / or separates the at least one receiving pixel and at least one dark pixel of the pixel array from each other. The pixel array is configured to generate and output a first reference signal by reading the reference receiving pixel for a third functional test, in particular for acquiring first reference data. The connecting unit is configured to couple the pixel array to the processing unit at (pre-)determined time intervals in order to feed the first reference signal into the processing unit for signal processing during the third functional test, in particular for acquiring the first reference data. In other words, the reference signal can comprise the first reference signal; in particular, the reference signal can be the first reference signal.Preferably, the connection unit is configured to couple the pixel array with the processing unit (at predetermined times) during and / or between each illumination phase of the distance measurement for the third functional test. Preferably, the connection unit is configured to couple the pixel array with the processing unit at the same acquisition rate as the distance measurement for the third functional test. The at least one reference receiving pixel can, for example, be a pixel located between the at least one receiving pixel and the dark pixel. The reference receiving pixel can also be referred to as a "buffer pixel," for example.The reference receiving pixel can advantageously separate the at least one receiving pixel and the at least one dark pixel from each other, for example, to reduce or avoid crosstalk between the at least one receiving pixel and the at least one dark pixel. The reference receiving pixel may be unusable for receiving light and generating the received signal, but still be usable for the second functional test. Additionally or alternatively, the reference receiving pixel can be configured to receive reference light focused (only) on the area of ​​the reference receiving pixel for generating the first reference signal. The reference light can be generated, for example, by a dedicated reference illumination unit or supplied to the reference receiving pixel by a reference light optic. The first reference signal can, for example, have a signal amplitude greater than zero.The signal amplitude of the first reference signal can be greater than the signal amplitude of the dark signal. Preferably, for the third functional test, several data sets of first reference data are recorded between or during each illumination phase of the distance measurement.

[0021] Preferably, the pixel array is configured to use different settings for each acquisition of a data set of initial reference data, in particular different illumination times for the reference receiving pixel and / or different integration times for reading out the reference receiving pixel. Likewise, the optoelectronic receiver can be configured to use different settings for each acquisition of a data set of initial reference data, in particular different frequencies for the reference light and / or different phase angles between the reference light and the reference receiving pixel. This third functional test can detect errors in the optoelectronic receiver, and in particular in both the pixel array and downstream components, such as...The third functional test detects the connection unit, the processing unit, and / or an (optional) data preprocessing unit during operation of the optoelectronic receiver, further improving its functional reliability. At least one reference receiving pixel may also be affected by external influences (e.g., transmitted light from other sensors and / or ambient light) during the third functional test. Therefore, the third functional test verifies whether the optoelectronic receiver remains functional even under external influences.

[0022] It is understood that the first, second, and third functional tests can be implemented in any combination within the optoelectronic receiver. For example, the second and / or third functional test can be implemented in place of the first. Advantageously, combining several of the functional tests, especially all of them, allows the optoelectronic receiver—particularly the pixel array, the interconnect unit, the processing unit, and / or an (optional) data preprocessing unit—to be tested across its entire dynamic range, thereby further improving the reliability of the optoelectronic receiver.

[0023] According to another embodiment, the components of the optoelectronic receiver, in particular the signal generator, are designed and / or pre-installed for calibration, and especially initial calibration, of the optoelectronic receiver. In this way, the components of the optoelectronic receiver can be used for several different purposes and thus more efficiently. At the same time, additional hardware structures, which would have been necessary, for example, for providing the diagnostic signal, can be eliminated. This can increase the overall efficiency and / or performance of the optoelectronic receiver, particularly with regard to its functional safety. Preferably, the usability of a conventional receiver for safety applications can be achieved.

[0024] According to another embodiment, the diagnostic signal is static or variable.

[0025] According to another embodiment, the signal generator is configured to change the amplitude of the diagnostic signal during a diagnostic run (i.e., a so-called "sweep"). The first functional test can thus include the diagnostic run; in particular, the first functional test can be the diagnostic run itself. In this way, the optoelectronic receiver, and especially the processing unit, can be tested across its entire dynamic range in a single diagnostic run, which can increase the degree of diagnostic coverage. In particular, various components and complex functions of the processing unit can be checked and / or monitored in a simple and flexible manner.For example, single-ended saturation comparators (if present), an (analog) correlated double sampling (CDS) function of an amplifier and its circuitry, gain selection comparators, various gain settings of the amplifier, and an analog-to-digital converter (ADC) can be checked and / or monitored across the entire dynamic range up to saturation.

[0026] According to a further embodiment, the signal generator is configured to test the entire dynamic range of the optoelectronic receiver during the diagnostic run, preferably including single-ended saturation and / or saturation of an analog-to-digital conversion, i.e., ADC saturation. Single-ended saturation can be understood to mean that the amplitude of the diagnostic signal corresponds to the saturation of a memory element of the receiving pixel.

[0027] According to another embodiment, the signal generator is configured to use different slopes for changing the amplitude of the diagnostic signal during the diagnostic run. The slope, which can also refer to a step size, can be selected depending on the gain setting of an amplifier in the processing unit, or vice versa. Using different slopes or step sizes allows for denser sampling for weak signals (and, for example, higher signal gain) while simultaneously providing a large dynamic range for stronger signals (and, for example, lower signal gain). In other words, a higher number of sampling points can be achieved within a given signal range. Furthermore, application-specific diagnostics of the optoelectronic receiver can be enabled.

[0028] According to a further embodiment, when monitoring at least one other component of the optoelectronic receiver, the test data generated is replaced by the diagnostic data. For example, the other component could be an amplifier. The (known) diagnostic data can reveal which data the amplifier should output, allowing the amplifier to be checked. Consequently, the output and / or further processing of the data generated by the optoelectronic receiver can be more reliable.

[0029] According to a further embodiment, the diagnostic data and the dark signal data, the first reference data and / or actual measurement data are combined in at least one combined output image. It is also conceivable that, if applicable, the multiple data sets of diagnostic data and the multiple data sets of dark signal data, the multiple data sets of first reference data and / or actual measurement data can also be combined in at least one combined output image.

[0030] According to another embodiment, several combined output images (e.g., a stack of output images) are generated (and output) during the diagnostic run. For example, different start and / or end points and / or different step sizes of the input diagnostic signal can be taken into account when generating the multiple combined output images, thereby achieving better coverage of the input / output signal and / or more application-specific coverage.

[0031] According to another embodiment, diagnostic data acquired during the diagnostic run are appended piecemeal to the actual measurement data to generate (and output) the multiple combined output images. Generating multiple output images facilitates further processing, particularly enabling stepwise processing.

[0032] The further processing or analysis of the diagnostic data in the output images by a downstream processor, FPGA, and / or SoC—for example, the data processing unit mentioned here—can thus begin early and at least partially occur while the data processing unit is still waiting for the remaining output images and therefore for the complete measurement dataset. Once the complete measurement dataset is received, the depth map can then be calculated from the raw data. This better distributes the computational load and any potential memory bandwidth usage by the data processing unit over time, and the evaluation of the diagnostic data does not reduce the available computing power for tasks such as creating the depth map.

[0033] One advantage of generating combined output images is that the total time required for the optoelectronic receiver to be active, and thus consume power, for each distance measurement or frame, can be reduced. This is because the additional time needed to prepare and / or start the diagnostic image acquisition is eliminated, as only the output image for the actual measurement data (live measurement data image) is enlarged by, for example, additional lines of diagnostic data. This time offset can therefore be avoided.

[0034] According to a further embodiment, the pixel array comprises a first output (for example, an output terminal) for outputting a first signal component of the received signal and a second output (separate from the first output) for outputting a second signal component of the received signal, wherein a first input of the connection unit is connected to the first output of the pixel array and a second input of the connection unit is connected to the second output of the pixel array. In particular, the first input of the connection unit can be connected to the first output of the pixel array and the second input of the connection unit can be connected to the second output of the pixel array, directly or indirectly, such that the first signal component and the second signal component of the received signal can be fed into the connection unit and consequently into the processing unit.

[0035] According to a further embodiment, the optoelectronic receiver comprises a first signal generator for generating a first diagnostic signal and a second signal generator for generating a second diagnostic signal, wherein the connecting unit is connected to the first output of the pixel array, the second output of the pixel array, the first signal generator, the second signal generator, a first input of the processing unit and a second input of the processing unit, and is configured to selectively couple the first and second outputs of the pixel array to the first and second inputs of the processing unit or the first and second signal generators to the first and second inputs of the processing unit.As a result, either the first and second signal components of the received signal (and / or the reference signal) or the first and second diagnostic signal can be fed into the processing unit for signal processing.

[0036] It is understood that the connection unit can be configured to couple the first signal generator to the first input of the processing unit and the second signal generator to the second input of the processing unit at (pre-)defined time intervals for the initial functional test, particularly for recording diagnostic data. A first output of the connection unit can be connected to the first input of the processing unit, and a second output of the connection unit (separate from the first output) can be connected to the second input of the processing unit.

[0037] Preferably, the first diagnostic signal is different from the second diagnostic signal and, for example, has a different amplitude.

[0038] According to another embodiment, the first input of the connection unit is connected to both the first and the second signal generator (for supplying the first and second diagnostic signals, respectively), and the second input of the connection unit is connected to both the first and the second signal generator (for supplying the first and second diagnostic signals, respectively).

[0039] According to a further embodiment, the connecting unit is configured to couple, preferably alternately, the first signal generator with the first input of the processing unit and the second signal generator with the second input of the processing unit, or the first signal generator with the second input of the processing unit and the second signal generator with the first input of the processing unit, for the first functional test, in particular for the acquisition of the diagnostic data. In other words, for the first functional test, either the first signal component of the received signal can be replaced with the first diagnostic signal and the second signal component of the received signal with the second diagnostic signal, or the first signal component of the received signal can be replaced with the second diagnostic signal and the second signal component of the received signal with the first diagnostic signal, preferably alternately, for the subsequent signal processing.This design of the optoelectronic receiver (and in particular the connection of the inputs of the linking unit to both the first and the second signal generator) and the alternating coupling allows the dynamic range (and preferably the full dynamic range) of the optoelectronic receiver to be covered or checked with a smaller number, for example half the number, of signal generator settings (within a diagnostic run).

[0040] The interconnection unit can, for example, include a first multiplexer comprising: a first input connected to the first output of the pixel array for feeding in the first signal component of the received signal (and / or the reference signal) of the pixel array; a second input connected to the first signal generator for feeding in the first diagnostic signal; a third input connected to the second signal generator for feeding in the second diagnostic signal; and an output for outputting the first diagnostic signal, the second diagnostic signal, or the first signal component of the received signal (and / or the reference signal). Furthermore, the interconnection unit can include a second multiplexer comprising: a first input connected to the second output of the pixel array for feeding in the second signal component of the received signal (and / or the reference signal).a second input connected to the first signal generator for supplying the first diagnostic signal, a third input connected to the second signal generator for supplying the second diagnostic signal, and an output for outputting the first diagnostic signal, the second diagnostic signal, or the second signal component of the received signal (and / or the reference signal), wherein the first multiplexer and the second multiplexer may be configured to simultaneously output the first diagnostic signal and the second diagnostic signal for the first functional test, in particular for recording the diagnostic data, wherein the first multiplexer may output the first diagnostic signal and the second multiplexer the second diagnostic signal, or vice versa. Preferably, the first multiplexer and the second multiplexer alternate in outputting the first diagnostic signal and the second diagnostic signal. It is understood thatThe first and second multiplexers can each have more than three inputs and more than one output. Furthermore, there can be more than two multiplexers, for example, three, four, or more.

[0041] According to another embodiment, the first diagnostic signal and the second diagnostic signal at the outputs of the connection unit and / or at the inputs of the processing unit define a differential diagnostic signal with respect to or through the processing unit, wherein the differential diagnostic signal has a positive or a negative polarity depending on the coupling setting of the connection unit.

[0042] According to another embodiment, the connecting unit is designed to invert the polarity of the differential diagnostic signal, and preferably to invert it multiple times during the diagnostic run.

[0043] According to another embodiment, the first and / or the second diagnostic signal is / are static or variable.

[0044] According to a further embodiment, the first and / or second signal generator(s) is / are configured to change the amplitude of the first and / or second diagnostic signal during the diagnostic run. Preferably, the first and second signal generators are configured to alternately change the amplitude of the first diagnostic signal and the amplitude of the second diagnostic signal during the diagnostic run; that is, one diagnostic signal is changed while the other initially remains constant, in order to be changed in the next round.

[0045] For example, the connection unit can allow the polarity of the input differential diagnostic signal to be reversed by switching the coupling with the first or second signal generator. In this way, the entire dynamic range of both polarities can be checked or covered in a single diagnostic run with a smaller number of generated diagnostic signal values, for example, only half the number. The signal generators, considered individually, do not need to cover the entire differential range, since the polarity reversal or switching enables the testing of a diagnostic signal with inverted polarity without having to traverse the entire dynamic range of both polarities (with respect to each individual signal generator).

[0046] According to one embodiment, the first and / or second signal generator is / are configured to test the entire dynamic range of the optoelectronic receiver in the diagnostic run, preferably including single-ended saturation and / or ADC saturation.

[0047] According to a further embodiment, the first and / or second signal generator(s) is / are configured to use different slopes (in particular, different step sizes) for changing the amplitude of the first and / or second diagnostic signal during the diagnostic run. Specifically, a controller can be provided that controls the first and / or second signal generator such that the different slopes for changing the amplitude of the first and / or second diagnostic signal result. By selecting the initial values ​​and slopes, it may be possible to eliminate the need to vary one of the two signal generators during the diagnostic run, which can simplify the diagnostic process.

[0048] According to a further embodiment, the processing unit comprises at least one amplifier, in particular a differential amplifier, for signal amplification. The amplifier can have a first input and a second input, wherein, for example, the first input of the amplifier can be connected to the output of the first multiplexer and the second input of the amplifier can be connected to the output of the second multiplexer. The amplifier can, for example, be a programmable differential amplifier. The amplifier can be a programmable differential amplifier with a differential output. The amplifier can be configured to provide analog correlated double sampling (CDS), amplifier offset cancellation, and / or pixel reset voltage subtraction.

[0049] According to another embodiment, the processing unit comprises an analog-to-digital converter (ADC). Preferably, the amplifier is connected (directly or indirectly) to the ADC on its output side. For example, the interconnect unit with the two multiplexers, the amplifier, and the ADC can be connected in series. The ADC can, for example, be a differential input ADC.

[0050] The optoelectronic receiver can optionally include a (programmable) data preprocessing unit configured to process an output signal from the optoelectronic receiver's analog-to-digital converter, and in particular to provide normalization of various gain settings of the processing unit's amplifier and / or format conversion of the digital output signal from the analog-to-digital converter, and preferably to provide format conversion of digital data based on the digital output signal of the analog-to-digital converter before transmission to a downstream data processing unit. It is understood that, by means of the procedures described herein and the design and configuration of the optoelectronic receiver, errors in the data preprocessing unit can also be detected during the operation of the optoelectronic receiver, since, for example,Differences can be observed between diagnostic data that was incorrectly pre-processed by the data pre-processing unit and diagnostic data that was pre-processed as expected.

[0051] According to a further embodiment, the processing unit further comprises at least one gain selection comparator, which is connected to the amplifier and is configured to compare the received signal, the reference signal, or the diagnostic signal, in particular the differential diagnostic signal, with at least one gain selection threshold, so that the amplifier's gain can be selected based on an output signal of the gain selection comparator. The gain selection comparator can be a fully differential gain selection comparator. The selectable gain factors can be programmable. The number of gain selection comparators can depend on and scale with the available gain factors. The at least one gain selection threshold can be calibration-dependent and / or programmed (e.g., by a controller).At least one gain selection threshold can be generated, for example, using at least one DAC.

[0052] For example, the processing unit can comprise at least one first and one second gain selection comparator (for example, two fully differential gain selection comparators) connected to the amplifier and configured to compare the (differential) received signal or the (differential) diagnostic signal (or other signals such as the reference signal) with a first, in particular negative, gain selection threshold and a second, in particular positive, gain selection threshold, so that the amplifier's gain can be selected based on an output signal from the gain selection comparators. The absolute values ​​of the first and second gain selection thresholds can be equal or different. Preferably, the values ​​are equal. In other words, for each polarity of a gain selection threshold (orA gain selection comparator may be present (its magnitude). This allows for the detection of a gain falling below the selection threshold (negative polarity) and a gain exceeding the selection threshold (positive polarity), enabling the gain factor to be switched accordingly. The signal components of the (differential) received signal and the (differential) diagnostic signal can be interchangeably fed to the gain selection comparators; that is, the first signal component of the received signal or one of the diagnostic signals can be fed into one input of each gain selection comparator, and the second signal component of the received signal or the other diagnostic signal can be fed into another input of the gain selection comparator, or vice versa.In this way, the same gain selection threshold can be used, especially if the polarity of the differential diagnostic signal is reversed.

[0053] According to another embodiment, the pixel array comprises a plurality of receiving pixels, wherein the plurality of receiving pixels are arranged in columns and / or rows. For example, the pixel array can have 512 or 1024 columns and 512 or 1024 rows of receiving pixels, respectively. For example, for each (differential) receiving pixel of the pixel array, there can be a first output for outputting a first signal component of the received signal (of the respective receiving pixel) and a second output for outputting a second signal component of the received signal (of the respective receiving pixel).Preferably, for each column and / or row of the pixel array, there is a first output for the output of a first signal component of a (differential) received signal (of the respective column or row) and a second output for the output of a second signal component of the (differential) received signal (of the respective column or row).

[0054] According to a further embodiment, a connection unit and a processing unit are provided for each individual column and / or row of the pixel array. Alternatively, a connection unit and a processing unit can be combined for several columns and / or rows and / or provided only for specific columns and / or rows. In other words, the connection unit and the processing unit, and in particular the amplifier, can be shared by several columns and / or rows of the pixel array, which can allow for efficient use of the hardware components. Providing a connection unit and a processing unit only for specific columns and / or rows of the pixel array can make it possible, during the initial functional test, to selectively replace only the actual (live) measurement data generated by the specific columns and / or rows of the pixel array with the diagnostic data.Preferably, columns and / or rows of the pixel array are selected for the initial functional test that are (in any case) unsuitable for distance measurement; for example, columns and / or rows at the edges of the pixel array, which may not be sufficiently illuminated. Furthermore, other test images or test data used to monitor other structures of the optoelectronic receiver can be replaced with the diagnostic data, as already mentioned. Preferably, the diagnostic signal fed into the connection unit and / or processing unit of a column and / or row is modified during the reading of the column and / or row (by reprogramming the associated signal generator). This allows for the acquisition of even more dynamic diagnostic data.

[0055] According to another embodiment, the same diagnostic signal is used for multiple columns and / or rows. Using the same diagnostic signal for multiple columns and / or rows can enable averaging of multiple measurements (i.e., multiple columns and / or rows), which can reduce noise before data processing. Furthermore, using the same diagnostic signal for multiple rows and / or columns can be combined with the polarity reversal described herein, for example, for every second row of the pixel array. Using the same diagnostic signal for multiple rows and / or columns can also be relevant when hardware resources, such as an amplifier, are shared between multiple columns of the pixel array and / or the image width of the test pattern is less than the number of columns.

[0056] According to another embodiment, the pixel array comprises a plurality of reference pixels. Preferably, the reference pixels are arranged in columns and / or rows. Preferably, the plurality of reference pixels comprises a plurality of dark pixels and / or a plurality of reference receiving pixels.

[0057] A further object of the invention is an optoelectronic sensor, in particular an optoelectronic sensor for distance measurement using (light) time-of-flight methods, preferably for use in an industrial plant and / or for safety applications, comprising at least one optoelectronic receiver described herein and at least one (in particular optoelectronic) light transmitter for emitting transmitted light.

[0058] The optoelectronic sensor is preferably a safety sensor. Preferably, the optoelectronic sensor comprises only one optoelectronic receiver.

[0059] The optoelectronic sensor can, for example, include a power supply.

[0060] The optoelectronic sensor can, for example, include a laser scanner or a camera system for distance measurement using (light) time-of-flight methods.

[0061] The light emitter can, for example, emit at least one laser beam.

[0062] The light emitter can be configured to transmit light into a detection area within an industrial plant. This transmitted light can then be reflected and / or re-emitted by the detection area, and in particular by objects within it, and received by the optoelectronic receiver as reflected light. Based on the generated and output received signal, distance values ​​of the objects (relative to the optoelectronic sensor) can then be determined.

[0063] According to one embodiment, the optoelectronic sensor further comprises at least one reference illumination unit for emitting reference light, which is guided within the optoelectronic receiver onto the pixel array, in particular the at least one receiving pixel. Preferably, the reference light is guided (directly) onto the pixel array, in particular the at least one receiving pixel, via a coupling element, in particular via at least one reflective area and / or a light guide.

[0064] According to another embodiment, the reference light is modulated with the same modulation frequency as the transmitted light emitted by the light source. Furthermore, the reference light can also match the transmitted light emitted by the light source with respect to the duty cycle, integration time, and / or phase shift relative to the pixel modulation. In this way, the implementation of the aforementioned illumination characteristics by the optoelectronic receiver can be verified. The phase position or phase shift can refer to the time difference between illumination and sampling at the pixel.

[0065] According to a further embodiment, the pixel array is configured to generate and output a second reference signal for a fourth functional test, in particular for the acquisition of second reference data, based on reference light received by means of the at least one receiving pixel. The interconnection unit is configured to couple the pixel array to the processing unit at (pre-)defined time intervals in order to feed the second reference signal into the processing unit for signal processing during the fourth functional test, in particular for the acquisition of the second reference data. Advantageously, the reference illumination unit can be configured to emit the reference light (only) for the fourth functional test, in particular for the acquisition of the second reference data, wherein the emitted reference light is received by the at least one receiving pixel (instead of the reflected / remitted transmitted light) as received light.Preferably, the interconnection unit is configured to couple the pixel array with the processing unit (at predetermined times) during each illumination phase of the distance measurement and / or between each illumination phase of the distance measurement for the fourth functional test. Preferably, the interconnection unit is configured to couple the pixel array with the processing unit at the same acquisition rate as the distance measurement for the fourth functional test. This fourth functional test allows for the detection of faults in the optoelectronic receiver, and in particular in both the pixel array and downstream components such as the interconnection unit, the processing unit, and / or the data preprocessing unit, during operation of the optoelectronic receiver, thus further improving the functional reliability of the optoelectronic receiver.The receiving pixels may also be affected by external influences during the fourth functional test. This fourth test therefore verifies whether the optoelectronic sensor functions correctly even under external conditions. Furthermore, it is conceivable that the fourth functional test (particularly by adjusting the reference light) could also be used to test for medium to high or even saturated signal amplitudes.

[0066] It is understood that the first, second, third, and fourth functional tests can also be implemented in any combination within the optoelectronic sensor. For example, instead of the first functional test, the second, third, and / or fourth functional test can be implemented in the optoelectronic sensor.

[0067] Advantageously, the combination of several of the functional tests, in particular all functional tests, can allow the optoelectronic sensor, especially the pixel array, the connection unit, the processing unit, the (optional) data preprocessing unit and (optional) other components, to be tested over the entire dynamic range, thereby further improving the safety of the optoelectronic sensor.

[0068] According to another embodiment, several data sets of second reference data are recorded between or during each illumination phase of the distance measurement.

[0069] According to a further embodiment, the pixel array and / or the reference illumination unit is / are configured to use different settings for each acquisition of a data set of second reference data, in particular different amplitudes for the reference light, different frequencies for the reference light, different phase angles for the reference light, different modulation frequencies for the reference light, and / or different integration times for reading out the received pixel. Integration time is understood to mean, in particular, the duration during which a pixel receives light and the charge in the pixel can thereby change.

[0070] According to another embodiment, the pixel array is configured to receive the reference light for the fourth functional test with at least one first receiving pixel and at least one second receiving pixel, and to illuminate the first and second receiving pixels with different illumination times and / or read them out with different integration times for generating and outputting the second reference signal. Such a procedure can also be described as an "interleaved high-dynamic-range mode" (HDR mode) and allows for the acquisition of even more "reference points," even if, for example, the pixel array, and in particular the at least one receiving pixel, is illuminated homogeneously with the reference light.

[0071] According to a further embodiment, the diagnostic data, the first reference data, the second reference data, the dark signal data, and / or actual measurement data are combined in at least one combined output image. It is also conceivable that, if applicable, the multiple data sets of diagnostic data, the multiple data sets of dark signal data, the multiple data sets of first reference data, and / or actual measurement data can also be combined in at least one combined output image.

[0072] According to a further embodiment, the optoelectronic sensor further comprises a data processing unit which is configured to monitor the operating state of the optoelectronic sensor, in particular the optoelectronic receiver, on the basis of the (recorded) diagnostic data, on the basis of the (recorded) first reference data, on the basis of the (recorded) second reference data and / or on the basis of the (recorded) dark signal data.

[0073] According to another embodiment, the data processing unit is configured to monitor whether the diagnostic data, the dark signal data, the first reference data, and / or the second reference data exhibit a signal amplitude within their respective expected ranges. Monitoring the signal amplitudes can provide a simpler basis for error detection. For example, it can be checked whether medium to high or even saturated signal amplitudes are discernible in the recorded data. Alternatively or additionally, the data processing unit can be configured to monitor, through statistical analysis, the number of received pixels, dark pixels, and / or reference received pixels that output a signal amplitude within their respective expected ranges.

[0074] Preferably, the respective expected range for the dark signal data, the first reference data, and / or the second reference data excludes a saturation range (of the optoelectronic receiver). It is understood that the expected range for the diagnostic data, the dark signal data, the first reference data, and the second reference data can each be different. The data processing unit can be configured to perform monitoring, in particular statistical evaluation, by calculating and evaluating a histogram, the standard deviation, the mean, the median, etc., which can be particularly advantageous if the pixel array, especially of the at least one receiving pixel, is homogeneously illuminated with the reference light.These procedures allow the data processing unit to monitor the operating status of the optoelectronic sensor without having to perform complex calculations such as correlation, phase difference calculations, or distance calculations (especially based on the second reference data). The data processing unit can be connected to the optoelectronic receiver's data preprocessing unit to receive and further process preprocessed data.

[0075] According to another embodiment, a warning signal is issued if the diagnostic data, dark signal data, first reference data and / or second reference data exhibit a signal amplitude outside their respective expected range and / or if the number of received pixels, dark pixels and / or reference received pixels exhibiting a signal amplitude outside their respective expected range is equal to or greater than a threshold value.

[0076] A further object of the invention is the use of an optoelectronic sensor described herein for distance measurement using time-of-flight methods.

[0077] A further object of the invention is a method for operational monitoring of an optoelectronic sensor described herein, in particular an optoelectronic receiver described herein, comprising generating at least one diagnostic signal, outputting a received signal generated based on received received light and / or a reference signal generated by reading at least one reference pixel, and selectively coupling the pixel array or the at least one signal generator with the processing unit, so that either the received signal and / or the reference signal or the diagnostic signal can be selectively fed into the processing unit for signal processing, wherein the signal generator is coupled to the processing unit at certain time intervals in order to feed the diagnostic signal into the processing unit for signal processing for a first functional test, in particular for recording diagnostic data.Preferably, the signal generator is coupled to the processing unit (at predetermined times) during, and in particular at the end of, each illumination phase of the distance measurement and / or between each illumination phase of the distance measurement. Preferably, the signal generator is coupled to the processing unit for the first functional test at the same acquisition rate as the distance measurement.

[0078] It is understood that the operating status of the optoelectronic sensor, in particular the optoelectronic receiver, can then be monitored based on the (recorded) diagnostic data, the (recorded) dark signal data, the (recorded) first reference data, and / or the (recorded) second reference data. A warning signal can be issued, for example, upon detection of a fault.

[0079] It is understood that what is described regarding the optoelectronic receiver according to the invention also applies to the optoelectronic sensor, the use of the optoelectronic sensor, and the method. This applies in particular to embodiments and advantages. Furthermore, it is understood that all features and embodiments disclosed herein can be combined unless expressly stated otherwise.

[0080] The invention is described below by way of example with reference to possible embodiments and the accompanying drawing. The drawing shows: Fig. 1 a schematic representation of an optoelectronic sensor; Fig. 2 a graphical representation of diagnostic data recorded by means of an optoelectronic sensor; Fig. 3 a graphical representation of diagnostic data and dark signal data recorded by means of an optoelectronic sensor; Fig. 4 a graphical representation of different amplifications; Fig. 5. Another graphical representation of the diagnostic data and dark signal data from Fig. 3.

[0081] The in Fig. 1 The optoelectronic sensor 1 shown, in particular for distance measurement using (light) time-of-flight methods and preferably for use in an industrial plant and / or for safety applications, comprises an optoelectronic receiver 100, a light transmitter 200 for emitting transmitted light, a power supply 300, a data processing unit 400 and a reference illumination unit 500.

[0082] The light transmitter 200 in Fig. 1 is configured to emit pulsed light into a detection area in an industrial plant. The emitted light from the light transmitter 200 can be reflected or remitted (i.e., diffusely reflected) by the detection area, and in particular by objects within the detection area, and reach the optoelectronic receiver 100 as received light.

[0083] The optoelectronic receiver 100, as it is in Fig. Figure 1 shows a first signal generator 10 for generating a first diagnostic signal A and a second signal generator 20 for generating a second diagnostic signal B. The signal generators 10, 20 include digital-to-analog converters (DACs) and are present and / or pre-installed for initial (electrical) calibration of the optoelectronic sensor 1.

[0084] The optoelectronic receiver 100 in Fig. Figure 1 further comprises a pixel array 30, which includes a plurality of receive pixels 32, a plurality of reference receive pixels 34, and a plurality of dark pixels 36. The plurality of receive pixels 32 are arranged in n columns and m rows, the plurality of reference receive pixels 34 are arranged in n columns and r rows, and the plurality of dark pixels 36 are arranged in n columns and p rows. It is understood that other arrangements of the receive pixels, dark pixels, and reference receive pixels are also possible. The pixel array 30 in Fig. 1 has 512 columns of receive pixels. The reference receive pixels 34 separate the receive pixels 32 and the dark pixels 36 from each other (see Fig. 1).

[0085] The pixel array 30 of the optoelectronic receiver 100 in Fig. The device is configured to generate and output a differential received signal based on the received light (per pixel). Distance measurement can then be performed using time-of-flight (light) propagation methods based on this differential received signal.

[0086] The pixel array 30 ( Fig. 1) is trained to perform a second functional test, in particular for recording dark signal data 39 ( Fig. 3) to generate and output a dark signal by reading the dark pixels 36.

[0087] Alternatively or additionally, the pixel array 30 ( Fig. 1) trained to generate and output a first reference signal for a third functional test, in particular for the recording of first reference data, by reading out the reference reception pixels 34.

[0088] The reference illumination unit 500 is configured to emit reference light, which is guided via a coupling element 510 within the optoelectronic sensor 1 to the receiving pixels 32 (and reference receiving pixels 34). The coupling element 510 can be at least one reflective area and / or an optical fiber. The reference light emitted by the reference illumination unit 500 is modulated with the same modulation frequency as the transmitted light emitted by the light source 200. The reference illumination unit 500 is configured to emit the reference light (only) for a fourth functional test, in particular for acquiring second reference data, wherein the emitted reference light is received by the receiving pixels 32 (instead of the reflected / remitted transmitted light) as received light.The pixel array 30 is designed to generate and output a second reference signal for the fourth functional test, in particular for the recording of the second reference data, based on reference light received by means of the receiving pixel 32.

[0089] The received signal output by the pixel array 30 comprises a first signal component and a second signal component. The same applies to the dark signal, the first reference signal, and the second reference signal. Preferably, the structure of the received pixels and those pixels for the dark signal is identical, for example, to achieve identical aging or change. The pixel array 30 includes, for each of the n columns, a first output 31 for outputting the first signal components and a second output 33 (separate from the first output) for outputting the second signal components. In the optoelectronic receiver 100 in the optoelectronic sensor 1, a connection unit 50 and a processing unit 40 are provided for each of the n columns of the pixel array 30 (not shown in Fig. 1 shown), so that each column of the pixel array 30 can be checked.

[0090] The optoelectronic receiver 100 in Fig. 1 further comprises at least one processing unit 40 for signal processing and at least one connection unit 50. As in Fig. Figure 1 shows a first input 51 of the connection unit 50 connected to the first output 31 of the pixel array 30, to the first signal generator 10, and to the second signal generator 20. A second input 53 of the connection unit 50 is connected to the second output 33 of the pixel array 30, to the first signal generator 10, and to the second signal generator 20. A first output 55 of the connection unit 50 is connected to a first input 41 of the processing unit 40. A second output 57 of the connection unit 50 is connected to a second input 43 of the processing unit 40.

[0091] The connection unit 50 in Fig. The connection unit 50 is configured to selectively couple either the first output 31 and the second output 33 of the pixel array 30 with the first input 41 and second input 43 of the processing unit 40, or the first signal generator 10 and the second signal generator 20 with the first input 41 and second input 43 of the processing unit 40, so that either the received signal, the dark signal, the first reference signal and / or the second reference signal, or the first and second diagnostic signals A, B, can be fed into the processing unit 40 for signal processing. For this purpose, the connection unit 50 comprises a first multiplexer 52 and a second multiplexer 54. It is understood that more than two multiplexers, for example three, four, or more multiplexers, may also be present.

[0092] In other words, in a first coupling setting, the (differential) received signal, the dark signal, the first reference signal and / or the second reference signal can be fed into processing unit 40 for signal processing, and, in contrast, in another, second coupling setting, the first and second diagnostic signals A, B can be fed into processing unit 40 for signal processing. Fig. Figure 1 shows the optoelectronic receiver 100 in a second coupling setting during the acquisition of diagnostic data.

[0093] The connection unit 50 in Fig. 1 is configured to couple the first and second signal generators 10, 20 with the processing unit 40 (at predetermined times) during, in particular at the end, of each illumination phase of the distance measurement and / or between each illumination phase of the distance measurement, in order to feed the first and second diagnostic signals A, B into the processing unit 40 for signal processing for a first functional test, in particular for recording diagnostic data.

[0094] Alternatively or additionally, the connection unit 50 is configured to couple the pixel array 30 with the processing unit 40 (at predetermined times) during each illumination phase of the distance measurement and / or between each illumination phase of the distance measurement, in order to feed the dark signal into the processing unit 40 for signal processing for the second functional test, in particular for recording the dark signal data.

[0095] Alternatively or additionally, the connection unit 50 is configured to couple the pixel array 30 with the processing unit 40 (at predetermined times) during each illumination phase of the distance measurement and / or between each illumination phase of the distance measurement, in order to feed the first reference signal into the processing unit 40 for signal processing for the third functional test, in particular for recording the first reference data.

[0096] Alternatively or additionally, the connection unit 50 is configured to couple the pixel array 30 with the processing unit 40 (at predetermined times) during and / or between each illumination phase of the distance measurement in order to feed the second reference signal into the processing unit 40 for signal processing during the fourth functional test, in particular for the acquisition of the second reference data. Several data sets of second reference data are acquired between or during each illumination phase of the distance measurement. The pixel array 30 and the reference illumination unit 500 are configured to use different settings for each acquisition of a data set of second reference data, in particular different amplitudes for the reference light, different phase angles for the reference light, different modulation frequencies for the reference light, and different integration times for the receiving pixels 32.Alternatively or additionally, the pixel array 30 is configured to receive the reference light for the fourth functional test with at least one first row of the m rows of the plurality of receiving pixels 32 and with at least one second row of the m rows of the plurality of receiving pixels 32, and to apply different integration times for generating the second reference signal for the receiving pixels 32 in the first and second rows of the m rows of the receiving pixels 32. Thus, the data is read out row by row, so that values ​​from receiving pixels 32 from different rows (but the same columns) are processed in a circuit assigned to each column.

[0097] It goes without saying that the above example can also be reversed with regard to columns and rows.

[0098] The first and / or second reference signal can be generated and evaluated, for example, as described in paragraphs

[0025] to

[0027] and

[0030] to

[0045] of EP 4 047 389 A1.

[0099] The optoelectronic receiver 100 in Fig. 1 further comprises a controller 60, such as a microprocessor, a (simpler) programmable state machine, or a field-programmable gate array (FPGA), configured to control the optoelectronic sensor 1, and in particular the optoelectronic receiver 100. The controller 60 can, for example, be pre-installed in the optoelectronic receiver 100 to control general functions of the pixel array 30 and / or the processing unit 40. The controller 60 can also be configured to control the connection unit 50, the light emitter 200, and / or the reference illumination unit 500 in order to implement the functional tests of the optoelectronic receiver 100.

[0100] The first and second diagnostic signals A, B define a differential diagnostic signal (B - A or A - B, depending on the coupling setting of the connection unit 50) at the outputs 55, 57 of the connection unit 50 and / or at the inputs 41, 43 of the processing unit 40 with respect to or through the processing unit 40. The differential diagnostic signal has a positive polarity if B - A or A - B is greater than zero, and a negative polarity if B - A or A - B is less than zero. The absolute amplitude of the first and second diagnostic signals A, B can be relevant for detecting or testing the saturation of a single part of the differential measurement (single-ended saturation).To test both polarities, it is sufficient to control the connection unit 50 in such a way that each of the two multiplexers 52, 54 uses the other signal generator 10, 20 as an input, so that a reversal of the polarity can take place without having to reconfigure either of the two signal generators 10, 20.

[0101] The connection unit 50 ( Fig. 1) is configured to alternately feed the first diagnostic signal A into the first input 41 of the processing unit 40 and the second diagnostic signal B into the second input 43 of the processing unit 40, or the first diagnostic signal A into the second input 43 of the processing unit 40 and the second diagnostic signal B into the first input 41 of the processing unit 40, for the first functional test. In other words, the connection unit 50 is configured to invert the polarity of the fed-in differential diagnostic signal B-A, A-B for the first functional test. The first and second diagnostic signals A, B are variable. The signal generators 10, 20 can be configured to alternately change the first and second diagnostic signals A, B during a diagnostic run for the first functional test.For example, one of the two signal generators 10, 20 can change the amplitude of the diagnostic signal A, B it generates, while the other of the two signal generators 10, 20 generates a constant diagnostic signal in order to then change the diagnostic signal A, B it generates in the next round. The first and / or second signal generator 10, 20 are configured to use different slopes for changing the amplitude of the first and second diagnostic signal A, B during a diagnostic run. Consequently, the first and / or second signal generator 10, 20 are configured to change the amplitude of the first and / or second diagnostic signal A, B, and thus the amplitude and / or polarity of the differential diagnostic signal B - A, A - B, during a diagnostic run, and accordingly perform a voltage sweep of the differential diagnostic signal.In combination with polarity reversal, the entire dynamic range of both polarities can be checked or covered in a single diagnostic run with a smaller number of generated diagnostic signal values, for example, only half the number. Signal generators 10 and 20, considered individually, do not need to cover the entire dynamic range, since polarity reversal allows testing of a differential diagnostic signal with inverted polarity (e.g., B - A, A - B) without requiring, for example, the differential diagnostic signal B - A to traverse the entire dynamic range of both polarities.

[0102] The processing unit 40 of the optoelectronic receiver in Fig. 1 comprises at least one amplifier 42, in particular a differential amplifier, for signal amplification. The processing unit 40 in Fig. 1 further comprises a first and a second gain selection comparator 46, 48, which are connected to the amplifier 42 and are configured to compare the (differential) received signal, the dark signal, the first reference signal, the second reference signal, or the diagnostic signal with a first, in particular negative, gain selection threshold and with a second, in particular positive, gain selection threshold, so that the gain of the amplifier 42 can be selected based on an output signal of the gain selection comparators 46, 48. The gain selection thresholds can be programmable and, for example, each generated by means of a DAC.

[0103] The in Fig. The processing unit 40 shown in Figure 1 further comprises an analog-to-digital converter (ADC) 44, wherein the amplifier 42 is connected to the output side of the ADC 44. In other words, the interconnection unit 50 is connected in series with the two multiplexers 52 and 54, the amplifier 42, and the ADC 44. The ADC 44 comprises an analog-to-digital converter with a differential input, which provides correspondingly signed output data.

[0104] The optoelectronic receiver 100 in Fig. 1 comprises a (programmable) data preprocessing unit 70, which is configured to process a digital output signal of the ADC 44. The data preprocessing unit 70 is configured to provide normalization of various gain settings of the amplifier 42 and / or format conversion of a digital output signal of the ADC 44. The data preprocessing unit 70 is configured to provide format conversion of digital data based on the digital output signal of the ADC 44 before transmission to the downstream data processing unit 400.

[0105] The data processing unit 400 of the optoelectronic sensor 1 ( Fig. 1) is connected to the data preprocessing unit 70 of the optoelectronic receiver 100 to receive and further process a preprocessed signal.

[0106] The data processing unit 400 ( Fig. 1) is designed to monitor the operating state of the optoelectronic sensor 1, in particular the optoelectronic receiver 100, based on the (recorded) diagnostic data, the (recorded) first reference data, the (recorded) second reference data and / or the (recorded) dark signal data. The data processing unit 400 is designed to monitor whether the diagnostic data ( Fig. 2, Fig. 3 and Fig. 5), the dark signal data ( Fig. 3 and Fig. 5) the first reference data and / or the second reference data exhibit a signal amplitude within their respective expected range. Alternatively or additionally, the data processing unit 400 is designed to monitor, by means of statistical evaluation, the number of receive pixels 32, dark pixels 36, and / or reference receive pixels 34 that output a signal amplitude within their respective expected range. The monitoring, in particular the statistical evaluation, is carried out by means of a calculation and evaluation of a histogram, the standard deviation, the mean, and / or the median. Through these procedures, the data processing unit 400 can monitor the operating state of the optoelectronic sensor without having to perform complex calculations such as correlation, calculation of phase differences, or calculation of distance values ​​(especially based on the second reference data). If the diagnostic data ( Fig. 2, Fig. 3 and Fig. 5), dark signal data ( Fig. 3 and Fig. 5) if the first reference data and / or the second reference data show a signal amplitude outside their respective expected range and / or if the number of received pixels 32, dark pixels 36 and / or reference received pixels 34 which show a signal amplitude outside their respective expected range is equal to or greater than a (respective) limit value, a warning signal may be issued.

[0107] Fig. 2 and Fig. Figure 3 each shows a graphical representation of diagnostic data ( Fig. 2 and Fig. 3) and dark signal data 39 ( Fig. 3) which is similar to or the same as in Fig. 1 the optoelectronic sensor 1 shown during a first functional test ( Fig. 2 and Fig. 3) and second functional tests ( Fig. 3) have been recorded. The in Fig. 2 and Fig. The three graphical representations of the recorded data shown can also be referred to as test images. The pixels in the test images corresponding to the diagnostic data ( Fig. 2 and Fig. 3) Due to the disconnection of the outputs of the pixel array 30 by the connection unit 50 during the first functional test, the pixels are no longer related to the individual pixels of the pixel array 30. The displayed pixel data is generated by the diagnostic signals A and B and therefore solely by targeted control of the signal generators 10 and 20, the connection unit 50, the processing unit 40, and the data preprocessing unit 70. The diagram is intended to illustrate the course of the voltage ramp, whereby each pixel of the displayed diagnostic data corresponds to a digital value output by the data preprocessing unit 70, which is derived from the differential diagnostic signal generated by the signal generators 10 and 20.

[0108] For the first functional test, in particular the diagnostic run, a voltage sweep was generated by the signal generators 10 and 20. For this purpose, the amplitude of the first diagnostic signal A, generated by a first signal generator 10, was varied with different slopes, and the polarity was reversed for every second row of the diagnostic data by means of the connection unit 50. That is, for every even-numbered row of the pixel array 30, the first diagnostic signal A generated by the first signal generator 10 was fed into the first input of the processing unit 40 (in particular, the amplifier 42), and the second diagnostic signal B generated by a second signal generator 20 was fed into the second input of the processing unit 40 (in particular, the amplifier 42).To generate the diagnostic data for the odd-numbered lines, the second diagnostic signal B, generated by the second signal generator 20, was fed into the first input 41 of the processing unit 40 (specifically, the amplifier 42), and the first diagnostic signal A, generated by the first signal generator 10, was fed into the second input 43 of the processing unit 40 (specifically, the amplifier 42). By selecting the starting values ​​and slopes, it is possible, as shown here, to ensure that the second diagnostic signal B output by the second signal generator 20 does not need to be varied, which further simplifies the voltage sweep. In the... Fig. 2 and Fig. The three graphical representations of the diagnostic data shown have been corrected to simplify the illustration of the polarity changes, so that the course of the resulting processed differential diagnostic signals is shown. As in Fig. 2 and Fig. The lower rows 35 of the pixel array 30 (in the range of fewer than 40 or 70 pixels) are marked as so-called single-ended saturation, meaning that the amplitude of the diagnostic signals A and / or B corresponds to the saturation of a storage element of the respective (differential) received pixel. It can be seen that, due to the tolerances of the individual processing units 40, single-ended saturation is reached at different amplitudes. Since it is possible to define areas in which saturation must or must not be present, this diagnostic data 35 can be used to check whether the detection of single-ended saturation is possible and, consequently, whether this detection still functions correctly during the acquisition of (live) measurement data. In other words, it can be detected whether one of the two signal components of the differential received signal or B is saturated.One of the storage elements of the (differential) receive pixel is saturated, so no measurement is possible. The polarity reversals performed for this data area also allow for the detection of single-ended saturation for both signal components, and thus for complete testing. The upper rows 37 of the pixel array 30 (in the range of more than 340 pixels or 360 pixels) correspond to saturation of the ADC, i.e., a signal that is too low or too high (difference) is present. The signal components A and B can, for example, be so far apart that the ADC saturates. The dark signal data 39 (.) recorded during the second functional test by reading the dark pixels 36 (. Fig. 3) have been added to the diagnostic data to determine the Fig. To generate the combined test pattern shown in 3. For recording the in Fig. 2 and Fig. The second and first functional tests, as shown in Figure 3, were performed in that order during an illumination phase of the distance measurement. A fault in the optoelectronic receiver 100 can be detected using the diagnostic data 35, 37 and / or dark signal data 39, for example, by detecting changes in the data compared to the normal state. These changes might include, for example, changes in the signal amplitude expected and / or permissible for the respective line of the (combined) test pattern, or saturation information expected or permissible depending on the line of the (combined) test pattern. Upon detection of a fault in the (combined) test pattern, a warning signal can be output, for example, by (the optoelectronic sensor 1).

[0109] Fig. Figure 4 shows a graphical representation of different gains G0 to G3 (or Gain0 to Gain3) with an amplifier 42 of an optoelectronic receiver 100, such as that found, for example, in Fig. Figure 1 illustrates the influence of the gains (or gain settings) on the digital output values ​​of the ADC 44. The two diagnostic signals A and B, generated by the two signal generators 10 and 20, are voltage signals and are output by the amplifier 42 as a differential diagnostic voltage, which is subsequently translated into digital form by the ADC 44. As shown in Fig. As shown in Figure 4, better coverage of the entire dynamic range of amplifier 42 and ADC 44 for small signal amplitudes, and therefore necessarily also high gains (e.g., G0), can be achieved by using a finer step size for the differential diagnostic voltage generated by signal generators 10 and 20, whereas for lower gains (e.g., G3), a larger step size for the generated differential diagnostic voltage is sufficient. Choosing a smaller step size for small signal amplitudes results in a greater number of different diagnostic voltages (and thus test points) that can be used for the initial functional test of the processing unit 40.

[0110] Fig. 5 shows another graphical representation of the diagnostic data from Fig. 3. Shows in more detail Fig. 5 the row-wise mean values ​​of the diagnostic data (taking polarity into account) in Fig.Figure 3 illustrates the different slopes or step sizes in the diagnostic signals for the diagnostic run. At the top, several lines of dark signal data (up to line 32) are shown, followed by a section with lines (approximately lines 32-40) where both signal components are alternately in single-ended saturation (due to the continuous polarity change). This is followed by a voltage sweep with different slopes and continuous polarity change through the connecting unit 50 during a voltage sweep through only one of the two signal generators 10, 20, with the final occurrence of ADC saturation for both polarities of the differential diagnostic signal at the bottom of the (combined) test image (from approximately line 380). Reference symbol list 1 optoelectronic sensor 10 first signal generator 20 second signal generator 30 pixel array 31 first output of the pixel array 32 reception pixels 33 second output of the pixel array 34 reference reception pixels 35 lines of the test pattern in single-ended saturation 36 dark pixels 37 lines of the test pattern in ADC saturation 39 Dark signal data 40 processing units 41 First input of the processing unit 42 amplifiers 43 Second input of the processing unit 44 analog-to-digital converters 46 First Gain Selection Comparator 48 Second Gain Selection Comparator 50 connection unit 51 First input of the connection unit 52 first multiplexer 53 second input of the connection unit 54 second multiplexer 55 first output of the connection unit 57 second output connection unit 60 Control 70 Data preprocessing unit 100 optoelectronic receivers 200 light transmitters 300 Power supply 400 data processing units 500 reference lighting units 510 coupling element

Claims

[1] Optoelectronic receiver (100), in particular for distance measurement using time-of-flight methods, comprising at least one signal generator (10, 20) for generating at least one diagnostic signal (A, B); a pixel array (30) with at least one, in particular differential, receiving pixel (32) and with at least one, in particular differential, reference pixel (34, 36), wherein the pixel array (30) is configured to generate and output a received signal based on received light received by means of the receiving pixel (32) and / or a reference signal by reading out the reference pixel (34, 36); at least one processing unit (40) for signal processing; and at least one connection unit (50) which is connected to the pixel array (30), the signal generator (10, 20) and the processing unit (40) and is configured to selectively couple either the pixel array (30) or the signal generator (10, 20) to the processing unit (40), so that either the received signal and / or the reference signal or the diagnostic signal (A, B) can be selectively fed into the processing unit (40) for signal processing, wherein the connecting unit (50) is configured to couple the signal generator (10, 20) with the processing unit (40) at certain time intervals, and preferably during, in particular at the end, of each illumination phase of the distance measurement and / or between each illumination phase of the distance measurement, in order to feed the diagnostic signal (A, B) into the processing unit (40) for signal processing for a first functional test, in particular for recording diagnostic data (35, 37). [2] Optoelectronic receiver according to claim 1, wherein the at least one reference pixel comprises at least one dark pixel (36), wherein the pixel array (30) is configured to generate and output a dark signal for a second functional test, in particular for recording dark signal data (39), by reading out the dark pixel (36), and wherein the connection unit (50) is configured to couple the pixel array (30) with the processing unit (40) at specific time intervals, and preferably during or between each illumination phase of the distance measurement, in order to feed the dark signal into the processing unit (40) for signal processing for the second functional test, in particular for recording the dark signal data (39); and / or wherein the at least one reference pixel comprises at least one reference receiving pixel (34) which receives reference light and / or separates the at least one receiving pixel (32) and at least one dark pixel (36) of the pixel array (30) from each other, wherein the pixel array (30) is configured to generate and output a first reference signal for a third functional test, in particular for recording first reference data, by reading out the reference receiving pixel (34), wherein the connecting unit (50) is configured to couple the pixel array (30) with the processing unit (40) at certain time intervals, and preferably during or between each illumination phase of the distance measurement, in order to feed the first reference signal into the processing unit (40) for signal processing for the third functional test, in particular for recording the first reference data. [3] Optoelectronic receiver according to claim 1 or 2, wherein the components of the optoelectronic receiver (100), in particular the signal generator (10, 20), are pre-installed for calibration of the optoelectronic receiver (100). [4] Optoelectronic receiver (100) according to one of the preceding claims, wherein the diagnostic signal (A, B) is static or variable, wherein the signal generator (10, 20) is preferably configured to change the amplitude of the diagnostic signal (A, B) during a diagnostic run, preferably to test the entire dynamic range of the optoelectronic receiver (100) during the diagnostic run, preferably including single-ended saturation and / or saturation of an analog-to-digital conversion, and / or preferably to use different slopes for changing the amplitude of the diagnostic signal (A, B) during the diagnostic run. [5] Optoelectronic receiver (100) according to any one of the preceding claims, wherein, during monitoring of at least one other component of the optoelectronic receiver (100), the test data generated are replaced by the diagnostic data, wherein the diagnostic data and the dark signal data (39), the first reference data and / or real measurement data are combined in at least one combined output image, wherein preferably several combined output images are generated during the diagnostic run, wherein preferably diagnostic data (35, 37) recorded during the diagnostic run are appended piecewise to the real measurement data in order to generate the several combined output images. [6] Optoelectronic receiver (100) according to any one of the preceding claims, wherein the pixel array (30) comprises a first output (31) for the output of a first signal component of the received signal and a second output (33) for the output of a second signal component of the received signal, wherein a first input (51) of the connection unit (50) is connected to the first output (31) of the pixel array (30) and a second input (53) of the connection unit (50) is connected to the second output (33) of the pixel array (30), wherein the optoelectronic receiver (100) comprises a first signal generator (10) for generating a first diagnostic signal (A) and a second signal generator (20) for generating a second diagnostic signal (B), wherein the connecting unit (50) is connected to the first output (31) of the pixel array (30), the second output (33) of the pixel array (30), the first signal generator (10), the second signal generator (20), a first input (41) of the processing unit (40) and a second input (43) of the processing unit (40) and is configured to selectively couple either the first and second output (31, 33) of the pixel array (30) to the first and second input (41, 43) of the processing unit (40) or the first and second signal generator (10, 20) to the first and second input (41, 43) of the processing unit (40). [7] Optoelectronic receiver (100) according to claim 6, wherein the first input (51) of the connection unit (50) is connected to the first and to the second signal generator (10, 20), wherein the second input (53) of the connection unit (50) is connected to the first and to the second signal generator (10, 20), wherein the connecting unit (50) is configured to couple, preferably alternately, the first signal generator (10) with the first input (41) of the processing unit (40) and the second signal generator (20) with the second input (43) of the processing unit (40) or the first signal generator (10) with the second input (43) of the processing unit (40) and the second signal generator (20) with the first input (41) of the processing unit (40) for the first functional test, in particular for the recording of the diagnostic data (35, 37). [8] Optoelectronic receiver (100) according to claim 6 or 7, wherein the first diagnostic signal (A) and the second diagnostic signal (B) define a differential diagnostic signal at the outputs (55, 57) of the connection unit (50) and / or at the inputs (41, 43) of the processing unit (40) with respect to or through the processing unit (40), wherein the differential diagnostic signal has a positive or a negative polarity depending on the coupling setting of the connection unit (50), wherein preferably the connection unit (50) is configured to invert the polarity of the differential diagnostic signal, and preferably to invert it multiple times during the diagnostic run;and / or wherein the first and / or the second diagnostic signal (A, B) are static or variable, wherein the first and / or second signal generator (10, 20) is / are preferably configured to change the amplitude of the first and / or second diagnostic signal (A, B) during the diagnostic run, preferably to test the entire dynamic range of the optoelectronic receiver (100) during the diagnostic run, preferably including single-ended saturation and / or saturation of an analog-to-digital conversion, and / or preferably to use different slopes for changing the amplitude of the first and / or second diagnostic signal (A, B) during the diagnostic run. [9] Optoelectronic receiver (100) according to any one of the preceding claims, wherein the processing unit (40) comprises at least one amplifier (42), in particular a differential amplifier, for signal amplification; and / or wherein the processing unit (40) comprises an analog-to-digital converter (44), wherein the amplifier (42) is preferably connected to the analog-to-digital converter (44) on the output side, wherein preferably the processing unit (40) further comprises at least one gain selection comparator (46, 48) which is connected to the amplifier (42) and is configured to compare the received signal, the reference signal or the diagnostic signal (A, B), in particular the differential diagnostic signal, with at least one gain selection threshold, so that the gain of the amplifier (42) can be selected based on an output signal of the gain selection comparator (46, 48). [10] Optoelectronic receiver (100) according to any one of the preceding claims, wherein the pixel array (30) comprises a plurality of receiving pixels (32), wherein the plurality of receiving pixels (32) are arranged in columns and / or rows, wherein preferably a connection unit (50) and a processing unit (40) are provided for each individual column and / or row, or wherein a connection unit (50) and a processing unit (40) are provided for several columns and / or rows together and / or only for certain columns and / or rows, wherein preferably columns and / or rows are selected for the first functional test which are unsuitable for distance measurement, and / or wherein preferably the same diagnostic signal (A, B) is used for several columns and / or rows;and / or wherein the pixel array (30) comprises a plurality of reference pixels (34, 36), wherein the plurality of reference pixels (34, 36) are preferably arranged in columns and / or rows, and / or wherein the plurality of reference pixels (34, 36) preferably comprises a plurality of dark pixels (36) and / or a plurality of reference receiving pixels (34). [11] Optoelectronic sensor (1), in particular for distance measurement using time-of-flight methods, preferably for use in an industrial plant and / or for safety applications, comprising at least one optoelectronic receiver (100) according to one of the preceding claims 1 to 10 and at least one light transmitter (200) for emitting transmitted light. [12] Optoelectronic sensor (1) according to claim 11, further comprising at least one reference illumination unit (500) for emitting reference light, which is guided within the optoelectronic receiver (100) onto the pixel array (30), in particular the at least one receiving pixel (32), wherein the reference light is preferably guided onto the pixel array (30), in particular the at least one receiving pixel (32), via a coupling element (510), in particular via at least one reflective area and / or a light guide, wherein the reference light is preferably modulated with the same modulation frequency as the transmitted light emitted by the light source (200), and wherein the pixel array (30) is configured to generate and output a second reference signal for a fourth functional test, in particular for recording second reference data, based on reference light received by means of the at least one receiving pixel (32), and wherein the connecting unit (50) is configured to couple the pixel array (30) with the processing unit (40) at certain time intervals, and preferably during or between each illumination phase of the distance measurement, in order to feed the second reference signal into the processing unit (40) for signal processing for the fourth functional test, in particular for recording the second reference data, wherein preferably several data sets of second reference data are recorded between or during each illumination phase of the distance measurement, wherein preferably the pixel array (30) and / or the reference illumination unit (500) is / are configured todifferent settings are used for each recording of a data set of second reference data, in particular different amplitudes for the reference light, different phase angles for the reference light, different modulation frequencies for the reference light, and / or different integration times for reading out the received pixel (32), and / or wherein the pixel array (30) is preferably configured to receive the reference light with at least one first received pixel and at least one second received pixel for the fourth functional test, and thereby to illuminate the first and second received pixels with different illumination times and / or to read them out with different integration times for generating and outputting the second reference signal. [13] Optoelectronic sensor (1) according to claim 11 or 12, wherein the diagnostic data, the first reference data, the second reference data, the dark signal data (39) and / or actual measurement data are combined in at least one combined output image, and / or further comprising a data processing unit (400) configured to monitor the operating state of the optoelectronic sensor (1), in particular the optoelectronic receiver (100), on the basis of the diagnostic data (35, 37), on the basis of the first reference data, on the basis of the second reference data and / or on the basis of the dark signal data (39), wherein the data processing unit (400) is preferably configured to monitor whether the diagnostic data (35, 37), the dark signal data (39), the first reference data and / or the second reference data have a signal amplitude within a respective expected range, and / or to monitor by means of a statistical evaluation,which number of receive pixels (32), dark pixels (36) and / or reference receive pixels (34) output a signal amplitude within their respective expected range, and wherein preferably a warning signal is output when the diagnostic data (35, 37), the dark signal data (39), the first reference data and / or the second reference data exhibit a signal amplitude outside their respective expected range and / or when the number of receive pixels (32), dark pixels (36) and / or reference receive pixels (34) outputting a signal amplitude outside their respective expected range is equal to or greater than a threshold value. [14] Use of an optoelectronic sensor (100) according to one of claims 11 to 13 for distance measurement using time-of-flight methods. [15] Method for operational monitoring of an optoelectronic sensor (1) according to one of claims 11 to 13, in particular of an optoelectronic receiver (100) according to one of claims 1 to 10, comprising generating at least one diagnostic signal (A, B); Output of a received signal generated based on received received light and / or a reference signal generated by reading out at least one reference pixel (34, 36); and Selective coupling of the pixel array (30) or of the at least one signal generator (10, 20) with the processing unit (40), so that either the received signal and / or the reference signal or the diagnostic signal (A, B) can be fed into the processing unit (40) for signal processing, wherein the signal generator (10, 20) is coupled to the processing unit (40) at certain time intervals, and preferably during, in particular at the end, of each illumination phase of the distance measurement and / or between each illumination phase of the distance measurement, in order to feed the diagnostic signal (A, B) into the processing unit (40) for signal processing for a first functional test, in particular for recording diagnostic data (35, 37).

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