OPTICAL DETECTION DEVICE FOR DETECTING OBJECTS AND METHOD FOR OPERATING A DETECTION DEVICE

Description

Technical area

[0001] The invention relates to an optical detection device for detecting objects, with at least one transmitting device for emitting light pulses, with at least one receiver with which the light pulses can be received, and with at least one control and evaluation device for controlling the at least one transmitting device and the at least one receiver and for evaluating light pulses received by the at least one receiving device.

[0002] Furthermore, the invention relates to a method for operating a detection device which is intended for detecting objects, wherein in the method light pulses are emitted by a transmitting device, the light pulses are received directly or indirectly by at least one receiver and the received light pulses are evaluated by at least one control and evaluation device. State of the art

[0003] An optical detection device for detecting objects is known on the market, comprising at least one transmitting device for emitting light pulses, at least one receiver with which the light pulses can be received as received signals, and at least one control and evaluation device for controlling the at least one transmitting device and the at least one receiver and for evaluating light pulses received by the at least one receiver.

[0004] WO 2017 / 200896 A2 discloses an optical detection device according to the preamble of claim 1. The detection device comprises a transmitter with a laser diode for emitting laser beams into a detection zone in the environment, as well as a laser detector for receiving laser beams reflected from objects in the environment. Furthermore, the detection device comprises a functional test device with a control circuit for outputting an error signal.

[0005] The invention is based on the object of designing a detection device and a method of the type mentioned at the outset, in which the efficiency and / or functional reliability of the detection device can be improved. Disclosure of the invention

[0006] This object is achieved by a detection device according to claim 1.

[0007] According to the invention, this comprises: a light-emitting first semiconductor element which has a blocking direction and a forward direction with respect to an electrical voltage, wherein the first semiconductor element emits light in its forward direction when an electrical voltage is applied, and at least one light-emitting second semiconductor element which has a blocking direction and a forward direction with respect to an electrical voltage, wherein the second semiconductor element emits light in its forward direction when an electrical voltage is applied, wherein the first semiconductor element and the at least one second semiconductor element are connected in parallel with respect to the electrical voltage and oppositely with respect to their blocking directions, and wherein at least one second semiconductor element is part of a functional testing device of the detection device.

[0008] According to the invention, an induction voltage generated by a light pulse from the first semiconductor element is additionally used to emit a corresponding further light pulse with the at least one second semiconductor element. In this way, the induction voltage can be reduced to protect the first semiconductor element. In addition, the light pulse generated from the induction voltage with the at least one second semiconductor element can be used either for a further measurement or to check the functionality of the detection device. In this way, the functional scope of the detection device can be expanded and / or the functional reliability of the detection device can be improved.

[0009] According to the invention, at least one second semiconductor element is part of a functional testing device for the optical detection device. The light emitted by this at least one semiconductor element can be used to test the functionality of the detection device. In particular, the light can be used to monitor light transmission in a housing or through windows of the detection device. Additionally or alternatively, the reflectivity of reflective surfaces of the detection device can be monitored. Contamination or water ingress can impair light transmission and / or reflection. This can be detected by comparing the results of a functional test measurement with the results of corresponding reference measurements.

[0010] The induction voltage arises at the moment the first semiconductor element is switched off after a light pulse due to the inductance of components, in particular electrical lines, connections, bonding wires, or the like, contained in the transmitting device. The first semiconductor element is short-circuited by the at least one second semiconductor element connected in antiparallel to protect it from the corresponding induction voltages. With correspondingly short and powerful light pulses and corresponding electrical currents, the first semiconductor element could otherwise be destroyed by such induction voltages.

[0011] Advantageously, the functional testing device can be implemented using at least one control and / or evaluation device. This can reduce the technical complexity of testing the functionality of at least parts of the detection device.

[0012] Advantageously, intensity-modulated light pulses can be generated using the first semiconductor element and at least one second semiconductor element.

[0013] Advantageously, the amount of emitted light, a pulse length, and / or a frequency of the light pulses of the first semiconductor element and / or at least one second semiconductor element can be adapted to the application of the detection device. Appropriate components, in particular electronic components, can be used for this purpose. With the at least one second semiconductor element, the power generated there can be converted into usable light energy with a high degree of efficiency, in particular approximately 90%. With the aid of the antiparallel-connected semiconductor elements, power loss can thus be significantly reduced.

[0014] With the at least one second semiconductor element, the heat output of the detection device can be dissipated from the first semiconductor element. This allows the detection device to be constructed more compactly overall.

[0015] Advantageously, the first semiconductor element and the at least one second semiconductor element can be arranged relatively close to one another. This allows for a better temporal relationship between the light pulses of the first semiconductor element and the light pulses of the second semiconductor element. Furthermore, this enables efficient operation of the semiconductor elements. Furthermore, improved heat exchange between the semiconductor elements can be achieved.

[0016] Advantageously, the first semiconductor element and the at least one second semiconductor element can be realized on a common semiconductor substrate. In this way, the first semiconductor element and the at least one second semiconductor element can be arranged closer to one another.

[0017] In an advantageous embodiment, the functional testing device can comprise means with which a quantity of light and / or a temporal profile of light pulses emitted by the at least one second semiconductor element can be determined, and from this, a transmission power of the first semiconductor element can be determined. In this way, a transmission power of the first semiconductor element can be determined, in particular losslessly, using the light pulses of the at least one second semiconductor element.

[0018] Advantageously, the amount of light emitted by the at least one second semiconductor element can be proportional to the amount of light emitted by the first semiconductor element. Additionally or alternatively, the amount of light emitted by the at least one second semiconductor element can be temporally dependent on the amount of light emitted by the first semiconductor element. In this way, the amount of light emitted by the first semiconductor element can be determined via the amount of light emitted by the at least one second semiconductor element.

[0019] In a further advantageous embodiment, the functional testing device can have means with which the functionality of at least one light deflection device of the detection device can be checked, wherein with the light deflection device, light pulses emitted by the first semiconductor element can be deflected into a monitoring area and / or reflected light pulses from the monitoring area can be deflected to at least one receiver, wherein at least one second semiconductor element can be directed towards the light deflection device in such a way that light pulses emitted by the at least one second semiconductor element can be deflected to at least one receiver and the functionality of the light deflection device can be inferred from the reflected light pulses that can be received by the at least one receiver.In this way, malfunctions related to the light-deflecting device can be detected efficiently and quickly. Countermeasures can be implemented more quickly. In particular, if a malfunction is detected, the transmission power of the first semiconductor element and / or the at least one second semiconductor element can be reduced. Furthermore, if a malfunction related to the light-deflecting device occurs, the detector device can be safely shut down.

[0020] Advantageously, the at least one light deflecting device can be illuminated with light pulses in a first optical axis by at least one second semiconductor diode. The reflected light pulses can be received by at least one receiver, which is arranged to match the at least one second semiconductor diode with respect to the first optical axis, and used to check the functionality of the at least one light deflecting device. In a second optical axis, which differs from the first optical axis, the at least one light deflecting device can be illuminated with light pulses by the first semiconductor diode, so that the light pulses are deflected into the surveillance area. Light pulses reflected from any objects in the surveillance area can be deflected in the second optical axis by the at least one light deflecting device to at least one receiver.

[0021] Advantageously, at least one receiver can be arranged within the housing of the detection device in such a way that it is illuminated with the reflected light pulses of at least one second semiconductor element when the light deflection device is set to a position in which the maximum light deflection is achieved.

[0022] In a further advantageous embodiment, the functional testing device can comprise means with which a temperature of the first semiconductor element and / or a wavelength of the light pulses that can be emitted by the first semiconductor element can be determined from light pulses that can be emitted by at least one second semiconductor element and received by at least one receiver. In this way, the temperature and / or the wavelength can be monitored losslessly and / or contactlessly, in particular continuously.

[0023] Advantageously, the first semiconductor element and the at least one second semiconductor element can be connected to one another in a heat-transfer manner by means of a medium, in particular a gaseous or solid medium, and can be arranged in close proximity to one another. In this way, the temperature of the at least one second semiconductor element approximately corresponds to the temperature of the first semiconductor element.

[0024] In a further advantageous embodiment, the functional testing device can comprise at least one optical bandpass filter, in particular with low quality, which is assigned to at least one receiver. The wavelength of the emitted light pulses changes with the temperature of the at least one second semiconductor element. With the aid of the at least one optical bandpass filter, the change in the signal amplitude of the received laser pulses in the corresponding wavelength range can be determined, and from this the temperature of the at least one second semiconductor element can be determined. The temperature of the first semiconductor element can be deduced from the temperature of the at least one second semiconductor element. Thus, the overall temperature of the first semiconductor element can be determined from the light pulses transmitted with the at least one second semiconductor element.

[0025] In a further advantageous embodiment, the functional testing device can comprise means for checking the degree of contamination in the optical path of the detection device. This makes it possible to detect any disruptions in light propagation due to contamination. Such contamination can have a significant impact on measurements with the detection device. As soon as contamination is detected, the system parameters of the detection device can be adjusted accordingly. Alternatively or additionally, cleaning measures can be initiated.

[0026] Advantageously, the degree of contamination in the optical path of the detection device can be determined by means of reflection measurements with at least one second semiconductor element and at least one receiver.

[0027] In a further advantageous embodiment, the functional testing device can comprise means with which a demodulation frequency and / or lock-in frequency of the first semiconductor element can be checked based on the frequency of light pulses that can be emitted by at least one second semiconductor element and received by at least one receiver. In this way, the demodulation frequency and / or the lock-in frequency of the first semiconductor element can be checked in a modulated detection device, in particular a LiDAR system, using the at least one second semiconductor element, since the light emission of the at least one second semiconductor element depends temporally on the light emission of the first semiconductor element.

[0028] Advantageously, the first semiconductor element and the at least one second semiconductor element can emit light with at least partially overlapping wavelength ranges or light with non-overlapping wavelength ranges. If the wavelength ranges of the first semiconductor element and the at least one second semiconductor element partially overlap, the light from the first semiconductor element and the at least one second semiconductor element can be used for corresponding measurements, in particular with identical or similar receivers.

[0029] Advantageously, the first semiconductor element and the at least one second semiconductor element can emit light at the same wavelength or in the same wavelength range. In this way, the semiconductor elements can complement each other.

[0030] If the wavelength ranges of the first semiconductor element and the at least one second semiconductor element do not overlap, the semiconductor elements can be optically decoupled with less effort.

[0031] Advantageously, at least one semiconductor element can emit light in a range invisible to the human eye. This allows the detection device to be used in technical areas where human eyes should not be irritated by the corresponding light emission. The detection device can thus be used in vehicles, particularly in road traffic.

[0032] Advantageously, at least one semiconductor element can emit light in the infrared range. Light in the infrared range is particularly suitable for object detection. Furthermore, light in the infrared range is invisible to the human eye.

[0033] Advantageously, the first semiconductor element and at least one second semiconductor element can be directed in the same spatial direction with respect to the emission of the light pulses and / or the first semiconductor element and at least one second semiconductor element can be directed in different spatial directions.

[0034] If the semiconductor elements are directed in the same spatial direction, their respective light pulses can be sent into the same spatial area, in particular the surveillance area.

[0035] Alternatively, the semiconductor elements can be directed in different spatial directions. One of the semiconductor elements can be used to illuminate a spatial region in the surrounding area. At least one other semiconductor element can be used to check the functionality of the transmitting device, in particular the optical detection device. For this purpose, the at least one other semiconductor element can be directed into the interior of the housing of the detection device.

[0036] Advantageously, the response speeds of the first semiconductor element and the at least one second semiconductor element can be approximately the same, preferably identical. This allows for better compensation of the induction voltages.

[0037] Advantageously, the first semiconductor element and the at least one second semiconductor element can be of the same design or the first semiconductor element and the at least one second semiconductor element can be of different design.

[0038] If the semiconductor elements are of the same design, the compensation of the induction voltages can be improved. In particular, this allows for consistent response times.

[0039] Alternatively, the semiconductor elements can be of different designs. This allows different wavelength ranges to be realized.

[0040] Advantageously, at least one semiconductor element can be a laser diode and / or at least one semiconductor element can be a light-emitting diode.

[0041] Advantageously, the at least one semiconductor element used to emit light for monitoring a spatial area can be a laser diode. Laser diodes allow for better control of light pulses in terms of direction, pulse length, and wavelength. Furthermore, very accurate results can be achieved with time-of-flight measurements using laser diodes.

[0042] Advantageously, at least one semiconductor element can be a light-emitting diode. Light-emitting diodes can be implemented more simply and inexpensively.

[0043] Advantageously, at least one semiconductor element can be a laser diode, and at least one semiconductor element can be a light-emitting diode. Alternatively, all semiconductor elements of the transmitting device can be laser diodes, or all semiconductor elements of the transmitting device can be light-emitting diodes. In this way, all semiconductor elements used in the transmitting device can be of the same design.

[0044] Advantageously, the first semiconductor element and the at least one second semiconductor element can be implemented in a common housing and / or as a common component, or the first semiconductor element and the at least one second semiconductor element can be implemented separately. In a common housing, the semiconductor elements can be easily installed and protected and shielded from the environment. As a common component, the semiconductor elements can be implemented in a particularly space-saving manner. Advantageously, the semiconductor elements can be implemented in a common chip or on a common substrate. The semiconductor elements can also be implemented separately, in particular in separate housings and / or as separate components.

[0045] Advantageously, the optical detection device can be used to determine object information about detected objects, in particular distances, directions, and / or speeds of the objects relative to the detection device. Additionally or alternatively, the detection device can be used to identify a detected object and / or perform gesture recognition.

[0046] Advantageously, the at least one detection device can operate according to a time-of-flight method. Optical detection devices operating according to the time-of-flight method can be designed and referred to as time-of-flight (TOF) systems, light detection and ranging (LiDAR) systems, laser detection and ranging (LaDAR) systems, or the like. In this case, a time of flight from the emission of a light pulse by at least one transmitter, in particular a light-emitting semiconductor element, to the reception of the corresponding reflected light pulse by at least one receiver is measured, and a distance between the detection device and the detected object is determined from this.

[0047] Advantageously, the at least one detection device can be a scanning system. A monitoring area can be scanned using light pulses. For this purpose, the corresponding light pulses can be pivoted across the monitoring area with respect to their propagation direction. At least one light deflection device, in particular a deflection mirror device, can be used for this purpose.

[0048] The detection device can advantageously be a laser-based distance measuring system. The laser-based distance measuring system can have at least one laser diode as the light source of the transmitting device. With the at least one laser diode, in particular, pulsed transmission beams can be transmitted as transmission signals. The laser diode can emit transmission signals in frequency ranges that are visible or invisible to the human eye. Accordingly, at least one receiver can have a detector, in particular a photodiode, designed for the frequency of the emitted light. The laser-based distance measuring system can advantageously be a laser scanner. With a laser scanner, a surveillance area can be scanned, in particular with pulsed laser beams.

[0049] Advantageously, at least one light-emitting semiconductor element can have at least one surface emitter. A surface emitter, also known as a vertical-cavity surface-emitting laser (VCSEL), is a semiconductor laser in which the light is emitted perpendicular to the plane of the semiconductor chip.

[0050] The invention can be used in a vehicle, in particular a motor vehicle. Advantageously, the invention can be used in a land vehicle, in particular a passenger car, truck, bus, motorcycle, or the like, an aircraft, and / or a watercraft. The invention can also be used in vehicles that can be operated autonomously or at least partially autonomously. Furthermore, it can also be used in a stationary detection device, in particular for traffic control or monitoring.

[0051] The detection device can advantageously be connected to or be part of at least one electronic control device of the vehicle, in particular a driver assistance system and / or a chassis control system and / or a driver information device and / or a parking assistance system or the like. In this way, the object data acquired by the detection device, in particular the distance, orientation and / or relative speed of an object relative to the vehicle, can be transmitted to the control device and used to influence driving functions, in particular the speed, a braking function, a steering function, a chassis control system and / or the output of an information and / or warning signal, in particular for the driver or the like. The detection device can also be used in conjunction with a recognition device for movement patterns, in particular gesture recognition.In this way, functions of the vehicle, in particular the opening of doors, a tailgate, a trunk lid, a hood or the like, can be activated based on results of the detection device.

[0052] In a further advantageous embodiment, the functional testing device can have means with which a deflection position of a light deflection device can be determined.

[0053] Furthermore, the object is achieved according to the invention by the method according to claim 9.

[0054] This method comprises applying an electrical transmission voltage pulse in the forward direction to a light-emitting first semiconductor element and emitting a corresponding light pulse with the first semiconductor element, generating at least one induction voltage pulse which is directed opposite to the transmission voltage pulse with electrical inductances of the transmitting device at the moment the first semiconductor element is switched off, and applying the induction voltage pulse to at least one light-emitting second semiconductor element which is connected anti-parallel to the first semiconductor element, so that a light pulse is emitted by the at least one second semiconductor element as a result of the induction voltage pulse and is received directly or indirectly by at least one receiver, and the functionality of at least parts of the detection device is inferred from the received light pulse.

[0055] In an advantageous embodiment of the method, a quantity of light and / or a temporal profile of the light from light pulses emitted by the at least one second semiconductor element can be determined, and a transmission power of the first semiconductor element can be determined therefrom. In this way, a transmission power of the first semiconductor element can be determined, in particular losslessly, using the light pulses of the at least one second semiconductor element.

[0056] In a further advantageous embodiment of the method, the functionality of at least one light deflection device of the detection device can be checked by directing at least one second semiconductor element toward the light deflection device in such a way that light pulses emitted by the at least one second semiconductor element are deflected to at least one receiver, and the functionality of the light deflection device is determined from the reflected light pulses received by the at least one receiver. In this way, malfunctions related to the light deflection device can be detected efficiently and quickly.

[0057] In a further advantageous embodiment of the method, a temperature of the first semiconductor element and / or a wavelength of the light pulses emitted by the first semiconductor element can be determined from the light pulses emitted by at least one second semiconductor element and received by at least one receiver. In this way, the temperature of the first semiconductor element and / or the wavelength of the light pulses emitted by the first semiconductor element can be monitored continuously, in particular without loss and / or contact.

[0058] In a further advantageous embodiment of the method, the degree of contamination in the optical path of the detection device can be monitored using light pulses that are emitted by the at least one second semiconductor element and received by at least one receiver. In this way, it can be detected if disruptions in light propagation occur due to contamination.

[0059] In a further advantageous embodiment of the method, a demodulation frequency and / or lock-in frequency of the first semiconductor element can be checked based on the frequency of light pulses emitted by the at least one second semiconductor element and received by at least one receiver. In this way, the demodulation frequency and / or lock-in frequency of the first semiconductor element can be checked in a modulated detection device, in particular a LiDAR system, using the at least one second semiconductor element, since the light emission of the at least one second semiconductor element depends temporally on the light emission of the first semiconductor element.

[0060] Furthermore, the features and advantages shown in connection with the detection device according to the invention and the method according to the invention and their respective advantageous embodiments apply to each other accordingly and vice versa. Short description of the drawings

[0061] Further advantages, features, and details of the invention will become apparent from the following description, in which exemplary embodiments of the invention are explained in more detail with reference to the drawings. Those skilled in the art will expediently consider the features disclosed in the drawings, the description, and the claims in combination individually and combine them into useful further combinations.

[0062] They show schematically Figure 1 shows a motor vehicle in front view, with an optical detection device for monitoring a monitoring area in the direction of travel in front of the motor vehicle for objects; Figure 2 shows a circuit diagram of a detection device according to a first embodiment of the motor vehicle from the Figure 1 ; Figure 3 a circuit diagram of a detection device according to a second embodiment for the motor vehicle from the Figure 1; Figure 4 shows a side view of the interior of a detection device according to a third embodiment of the motor vehicle from the Figure 1 ; Figure 5 a plan view of the interior of the detection device of the Figure 4

[0063] In the figures, identical components are provided with identical reference symbols. Embodiment(s) of the invention

[0064] In the Figure 1 A vehicle 10 is shown, for example, in the form of a passenger car in a front view. The vehicle 10 comprises an optical detection device 12 for detecting objects 14 in the direction of travel in front of the vehicle 10. The detection device 12 is arranged, for example, in the front bumper of the vehicle 10. An object 14 is in the Figure 2, which also shows a schematic circuit diagram of the detection device 12 according to a first exemplary embodiment. The objects 14 can be, for example, other vehicles, persons, animals, road markings, buildings, road surface irregularities, or other obstacles.

[0065] The detection device 12 can be connected to a driver assistance system of the vehicle 10, which is not of further interest here. The driver assistance system can support or control driving functions of the vehicle 10. With the help of the driver assistance system, the vehicle 10 can be operated semi-autonomously or autonomously.

[0066] The detection device 12 is, for example, a so-called LiDAR system in the form of a laser scanner. The laser scanner operates according to a light pulse time-of-flight method. It can be used to determine the distance, direction, and speed of the object 14 relative to the vehicle 10.

[0067] The detection device 12 is described below with reference to the Figure 2 explained in more detail.

[0068] The detection device 12 comprises a transmitting device 16 for transmitting first transmitted light pulses 18a and second transmitted light pulses 18b, a first receiver 20a for receiving first transmitted pulses 18a reflected by a possible object 14, and a second receiver 20b for receiving second transmitted light pulses 18b.

[0069] The detection device 12 further comprises a light deflection device 32, for example in the form of a rotatable deflection mirror, with which the first transmitted light pulses 18a can be deflected into a monitoring area 26. By pivoting the deflection mirror, the direction of the first transmitted light pulses 18a in the monitoring area 26 is pivoted, so that the area can be sampled, i.e., scanned, with the first transmitted light pulses 18a. Furthermore, the light deflection device 32 can be used to deflect the reflected first transmitted pulses 18a from the monitoring area 26 to the first receiver 20a.

[0070] Furthermore, the detection device 12 comprises a control and evaluation device 22, which is connected to the transmitting device 16, the receivers 20a and 20b, and the light deflecting device 32. The control and evaluation device 22 can control the transmitting device 16 and the light deflecting device 32, and the transmitted light pulses 18a and 18b received by the receivers 20a and 20b can be evaluated accordingly.

[0071] The transmitting device 16, the receivers 20a and 20b, the light deflection device 32 and the control and evaluation device 22 are arranged in a housing 28, which is in the Figure 2 is indicated by dashed lines as an example. On the side facing the monitoring area 26, the housing 28 has a translucent window 30.

[0072] The transmitting device 16 can transmit first transmitted light pulses 18a, which can be redirected into the monitoring area 26 by the light redirecting device 32. The first transmitted light pulses 18a are reflected by the object 14, returned to the detection device 12, redirected by the light redirecting device 32, and received by the first receiver 20a. The distance to the object 14 is determined by the control and evaluation device 22 from the light propagation time, i.e., the time between the transmission of the first transmitted light pulses 18a and the reception of the reflected first transmitted light pulses 18a.

[0073] The receivers 20a and 20b are designed as photodiodes, for example.

[0074] The transmitting device 16 comprises a first semiconductor element in the form of a first laser diode 24a for emitting the first transmitted light pulses 18a and a second light-emitting semiconductor element in the form of a second laser diode 24b for emitting the second transmitted light pulses 18b. For example, the laser diodes 24a and 24b can be laser diodes of the same design that can emit transmitted light pulses with the same wavelength. The laser diodes 24a and 24b, for example, emit light in the infrared range. Furthermore, the laser diodes 24a and 24b, for example, have the same response speeds.

[0075] The first laser diode 24a and the second laser diode 24b are connected in parallel with respect to an electrical voltage and oppositely with respect to their forward direction and their reverse direction, thus overall they are connected anti-parallel.

[0076] The first laser diode 24a is used to monitor the monitoring area 26.

[0077] As is known, electrical conductors in the circuit of the transmitting device 16 form inductances. The inductances generate a corresponding induced voltage pulse at the moment the first laser diode 24a is switched off after the first transmitted light pulse 18a has been emitted. The induced voltage pulse is directed opposite to the voltage pulse used to generate the first transmitted light pulse 18a. The second laser diode 24a acts as a protective diode, through which an electrical current following the induced voltage pulse is conducted. A second transmitted light pulse 18b is then emitted by the second laser diode 24a.

[0078] The second laser diode 24b is directed into the interior of the housing 28, i.e., in a different spatial direction than the first laser diode 24a. The second transmitted light pulses 18b emitted by the second laser diode 24b are received by the second receiver 20b.

[0079] The light paths of the first laser diode 24a and the second laser diode 24b are optically decoupled so that they do not interfere with each other.

[0080] For example, the first laser diode 24a, the second laser diode 24b, and any required additional electronic or electrical components can be implemented on a common circuit board. Alternatively, the first laser diode 24a and the second laser diode 24b can be implemented on a common substrate or in a common chip, optionally with additional electronic components.

[0081] In addition, the detection device 12 has a functional testing device 34 with which the functionality of the detection device 12 can be monitored. The functional testing device 34 comprises, for example, the second laser diode 24b, the second receiver 20b, and corresponding testing means 36, for example in the form of algorithms, in the control and evaluation devices 22, with which the corresponding functional tests can be performed.

[0082] The functional testing device 34 determines the light quantity and the temporal progression of the light of the transmitted light pulses 18b emitted by the second laser diode 24b and received by the second receiver 20b, and from this, a transmitted power of the first laser diode 24a is determined. This utilizes the knowledge that the light quantity emitted by the second laser diode 24b is proportional to the light quantity emitted by the first laser diode 24a. Furthermore, the light quantity emitted by the second laser diode 24b is temporally dependent on the light quantity emitted by the first laser diode 24a.

[0083] Furthermore, the functional testing device 34 determines a temperature of the first laser diode 24a and a wavelength of the first transmitted light pulses 18a, which are emitted by the first laser diode 24a, from the second transmitted light pulses 18b, which are emitted by the second laser diode 24b and received by the second receiver 20b. Thus, the temperature and wavelength are continuously monitored losslessly and without contact. The first laser diode 24a and the second laser diode 24b are preferably arranged close enough to one another to enable good heat transfer.

[0084] For temperature testing, the functional testing device 34 can, for example, comprise an optical bandpass filter, for example with a low quality, which is assigned to the second receiver 20b. The wavelength of the emitted second transmitted light pulses 18b changes with the temperature of the second laser diode 24b. Using the optical bandpass filter, the change in signal amplitude in the corresponding wavelength range is determined, and from this, the temperature of the second laser diode 24b is determined. Since the first laser diode 24a has a thermal connection to the second laser diode 24b, the temperature of the first laser diode 24a corresponds to the temperature of the second laser diode 24b. Thus, the temperature of the first laser diode 24a is determined from the second transmitted light pulses 18b.

[0085] In addition, the functional test device 34 determines the degree of contamination in the optical path of the detection device 12 using reflection measurements with the second laser diode 24b and the second receiver 20b. This allows detection of any disruptions in light propagation due to contamination. As soon as contamination is detected, system parameters of the detector device 12 that are not of further interest are adjusted accordingly. Cleaning measures are also initiated.

[0086] Furthermore, the functional testing device 34 checks a demodulation frequency and a lock-in frequency of the first laser diode 24a based on the frequency of the second transmitted light pulses 18b, which are emitted by the second laser diode 24b and received by the second receiver 20b. The light emission of the second laser diode 24b depends temporally on the light emission of the first laser diode 24a.

[0087] In the Figure 3 A detection device 12 according to a second embodiment is shown. The elements which are identical to those of the first embodiment from the Figure 2 are similar, are provided with the same reference numerals. In contrast to the first embodiment, in the second embodiment, both the first laser diode 24a and the second laser diode 24b are directed into the monitoring area 26 via the light deflection device 32.

[0088] The second receiver 20b is omitted in the second embodiment. The first receiver 20a serves to receive both the first transmitted light pulses 18a of the first laser diode 24a and the second transmitted light pulses 18b of the second laser diode 24b. The functional testing device 34 is used in the second embodiment analogously to the first embodiment.

[0089] In the Figures 4 and 5A detection device 12 according to a third embodiment is shown. The elements which are identical to those of the first embodiment from the Figure 2 are similar are provided with the same reference numerals.

[0090] In contrast to the first exemplary embodiment, in the third exemplary embodiment, the second laser diode 24b and the second receiver 20b are arranged with respect to the light deflection device 32 such that the light deflection device 32 is illuminated with the second transmitted light pulses 18b in a first optical axis 38 by the second laser diode 24b. In a second optical axis 40, which differs from the first optical axis 38, the light deflection device 32 is illuminated with first transmitted light pulses 18a by the first laser diode 24a, so that these are deflected into the surveillance area 26. First transmitted light pulses 18a reflected by any objects 14 in the surveillance area 26 are deflected in the second optical axis 40 by the light deflection device 32 to the first receiver 20a.

[0091] The second receiver 20a is arranged within the housing 28 in such a way that it is directly illuminated with the reflected second transmitted light pulses 18b when the light deflection device 32 is set to a position in which the maximum light deflection is achieved.

[0092] The second transmitted light pulses 18b therefore do not leave the housing 28.

[0093] In the third exemplary embodiment, in addition to the functional tests from the first exemplary embodiment, the functional testing device 34 checks the functionality of the light deflection device 32. The functionality of the light deflection device 32 is determined from the reflected second transmitted light pulses 18b received by the second receiver 20b. If malfunctions related to the light deflection device 32 are detected, countermeasures are taken. For example, the transmission power of the laser diodes 24a and 24b is reduced. Furthermore, the detector device is safely shut down.

[0094] In the Figures 6 and 7 A detection device 12 according to a fourth embodiment is shown. The elements which correspond to those of the third embodiment from the Figures 4 and 5 are similar are provided with the same reference numerals.

[0095] In contrast to the third exemplary embodiment, in the fourth exemplary embodiment, the functional testing device 34 additionally has an angular position detection element 42. The angular position detection element 42 is configured, for example, as a strip with locally modified optical properties. For example, the strip has a variable absorption for the transmitted light pulses 18b along its length.

[0096] The angular position detecting element 42 is, as shown in the Figure 6 shown, arranged below the window 30 on the inner wall of the housing 28, wherein its longitudinal direction runs perpendicular to a pivot axis 44 of the light deflection device 32.

[0097] The second laser diode 24b and the second receiver 20b are in comparison to the third embodiment in the Figure 6offset downward. The second laser diode 24b is directed obliquely toward the light deflection device 32. The receiver 20b is directed obliquely toward the angular position detection element 42.

[0098] The second transmitted light pulses 18b emitted by the second laser diode 24b are reflected by the light deflection device 32 and transmitted to the angular position detection element 42. Depending on the angular position of the light deflection device 32, the second transmitted light pulses 18b are modified at a corresponding location on the angular position detection element 42 by the optical property characteristic of the angular position detection element 42 at that location and are reflected or scattered as position light pulses 18c. The position light pulses 18c carry information about the angular position of the light deflection device 32. The position light pulses 18c are received by the second receiver 20b and converted into corresponding electrical position signals. The electrical position signals are evaluated by the test means 36 of the control and evaluation devices 22.From the electrical position signals, a deflection position, for example the angular position of the light deflection device 32, is determined and verified.

[0099] Using the angular position detection element 42, for example, information about the angular position of the light deflection device 32 can be determined at any time. Furthermore, it can be determined at any time, for example, whether the light deflection device 32 is oscillating. If it is detected that the light deflection device 32 is not oscillating, the detection device 12, in particular the emission of transmitted light pulses 18a and 18b, can be stopped for safety reasons.

[0100] In the third embodiment, the second receiver 20b can also be aligned differently than directly toward the angular position detection element 42. In this case, the position light pulses 18c can also be detected indirectly, for example, as multiple reflections, by the second receiver 20b.

[0101] In the illustrated embodiments, all or only some of the functional tests explained can be carried out.

[0102] In further embodiments not shown, the first laser diode 24a and the second laser diode 24b can have different designs. They can emit transmitted light pulses with different wavelengths. In this way, optical decoupling between the first laser diode 24a and the second laser diode 24b can be simplified. Instead of a laser diode, one of the two laser diodes 24a or 24b can also be another light-emitting semiconductor element, for example, a conventional light-emitting diode.

Claims

1. Optical detection apparatus (12) for detecting objects (14), - comprising at least one transmitting device (16) for emitting light pulses (18a, 18b), wherein transmitting device (16) has a light-emitting first semiconductor element (24a) embodied as a diode in order to irradiate a spatial region in the surroundings, said semiconductor element having a reverse direction and a forward direction with respect to an electrical voltage, wherein the first semiconductor element (24a) emits light (18a) when an electrical voltage is applied in its forward direction, - comprising at least one receiver (20a, 20b), by which the light pulses (18a, 18b) can be received, - comprising at least one control and evaluation device (22) for controlling the at least one transmitting device (16) and the at least one receiver (20a, 20b) and for evaluating light pulses (18a, 18b) received by the at least one receiver (20a, 20b), - and comprising a function checking device (34), characterized in that the at least one transmitting device (16) has - at least one light-emitting second semiconductor element (24b) which is embodied as a diode and which has a reverse direction and a forward direction with respect to an electrical voltage, wherein the second semiconductor element (24b) emits light (18b) when an electrical voltage is applied in its forward direction, - wherein the first semiconductor element (24a) and the at least one second semiconductor element (24b) are connected in parallel with respect to the electrical voltage and oppositely with respect to their reverse directions, - wherein the second semiconductor element (24b) is part of the function checking device (34) of the detection apparatus (12), and wherein at the moment when the first semiconductor element (24a) is turned off, with electrical inductances of the transmitting device (16), at least one induced voltage pulse is generated which is directed oppositely to the transmission voltage pulse, and the induced voltage pulse is applied to the at least one light-emitting second semiconductor element (24b), such that the at least one second semiconductor element (24b) emits a light pulse (18b) owing to the induced voltage pulse, and the receiver (20a, 20b) of the detection apparatus (12) is provided for directly or indirectly receiving the light pulse (24b) emitted by the second semiconductor element (24b), and the function checking device (34) is provided for deducing the functionality of at least parts of the detection apparatus (12) from the received light pulse (18b).

2. Detection apparatus according to Claim 1, characterized in that the function checking device (34) has means (20b, 24b, 36) with which a quantity of light and / or a temporal profile of light pulses (18b) which are emitted by the at least one second semiconductor element (24b) can be determined and a transmission power of the first semiconductor element (24a) can be determined therefrom.

3. Detection apparatus according to Claim 1 or 2, characterized in that the function checking device (34) has means (20b, 24b, 36) with which the functionality of at least one light deflection device (32) of the detection apparatus (12) can be checked, wherein by way of the light deflection device (32) light pulses (18a) emitted by the first semiconductor element (24a) are deflected into a monitoring region (26) and / or reflected light pulses (18a) from the monitoring region (26) are deflected to at least one receiver (20a), wherein at least one second semiconductor element (24b) is directed to the light deflection device (32) such that light pulses (18b) emitted by the at least one second semiconductor element (24b) can be deflected to at least one receiver (20b) and the functionality of the light deflection device (32) can be deduced from the reflected light pulses (18b) which can be received by the at least one second receiver (20b).

4. Detection apparatus according to any of the preceding claims, characterized in that the function checking device (34) has means (20b, 24b, 36) with which a temperature of the first semiconductor element (24a) and / or a wavelength of the light pulses (18a) which can be emitted by the first semiconductor element (24a) can be determined from light pulses (18b) which can be emitted by at least one second semiconductor element (24b) and can be received by at least one receiver (20b).

5. Detection apparatus according to any of the preceding claims, characterized in that the function checking device (34) comprises at least one optical bandpass filter assigned to at least one receiver (20b).

6. Detection apparatus according to any of the preceding claims, characterized in that the function checking device (34) has means (20b, 24b, 36) with which a degree of contamination in the optical path of the detection apparatus (12) can be checked.

7. Detection apparatus according to any of the preceding claims, characterized in that the function checking device (34) has means (20b, 24b, 36) with which a demodulation frequency and / or lock-in frequency of the first semiconductor element (24a) can be checked on the basis of the frequency of light pulses (18b) which can be emitted by at least one second semiconductor element (24b) and can be received by at least one receiver (20b).

8. Detection apparatus according to any of the preceding claims, characterized in that the function checking device (34) has means (42) with which a deflection position of a light deflection device (32) can be determined.

9. Method for operating a detection apparatus (12) provided for detecting objects (14), wherein in the method light pulses (18a, 18b) are emitted by a transmitting device (16), the light pulses (18a, 18b) are directly or indirectly received by at least one receiver (20a, 20b) and the received light pulses (18a, 18b) are evaluated by at least one control and evaluation device (22), characterized in that an electrical transmission voltage pulse in the forward direction is applied to a light-emitting first semiconductor element (24a) embodied as a diode and a corresponding light pulse (18a) is emitted by the first semiconductor element (24a), and at the moment when the first semiconductor element (24a) is turned off, with electrical inductances of the transmitting device (16), at least one induced voltage pulse is generated which is directed oppositely to the transmission voltage pulse, and the induced voltage pulse is applied to at least one light-emitting second semiconductor element (24b) which is embodied as a diode and which is connected in antiparallel with the first semiconductor element (24a), such that a light pulse (18b) is emitted by the at least one second semiconductor element (24b) owing to the induced voltage pulse, and is directly or indirectly received by at least one receiver (20b), and the functionality of at least parts of the detection apparatus (12) is deduced from the received light pulse (18b) by means of a function checking device (34).

10. Method according to Claim 9, characterized in that a quantity of light and / or a temporal profile of the light of light pulses (18b) which are emitted by the at least one second semiconductor element (24b) are / is determined and a transmission power of the first semiconductor element (24a) is determined therefrom.

11. Method according to Claim 9 or 10, characterized in that the functionality of at least one light deflection device (32) of the detection apparatus (12) is checked by virtue of the fact that at least one second semiconductor element (24b) is directed to the light deflection device (32) such that light pulses (18b) emitted by the at least one second semiconductor element (24b) are deflected to at least one receiver (20b) and the functionality of the light deflection device (32) is deduced from the reflected light pulses (18b) which are received by the at least one receiver (20b).

12. Method according to any of Claims 9 to 11, characterized in that a temperature of the first semiconductor element (24a) and / or a wavelength of the light pulses (18a) which are emitted by the first semiconductor element (24a) are / is determined from the light pulses (18b) which are emitted by at least one semiconductor element (24b) and are received by at least one receiver (20b).

13. Method according to any of Claims 9 to 12, characterized in that a degree of contamination in the optical path of the detection apparatus (12) is monitored by way of light pulses (18b) which are emitted by the at least one second semiconductor element (24b) and are received by at least one receiver (20b).

14. Method according to any of Claims 9 to 13, characterized in that a demodulation frequency and / or lock-in frequency of the first semiconductor element (24a) are / is checked on the basis of the frequency of light pulses (18b) which are emitted by the at least one second semiconductor element (24b) and are received by at least one receiver (20b).