DE102019112340A1 - TOF sensor system with a lighting device with an array of individual light sources - Google Patents

Abstract

A sensor system (100) and a method for three-dimensional detection of a scene (190) are described. The sensor system (100) has (a) an illuminating device (130a, 130b) for illuminating the scene (190) with illuminating light (131a, 131b; 331); (b) a measuring device (110) (b1) for receiving measuring light (196a, 196b) which is at least partially backscattered illumination light (131a, 131b; 331) from at least one object (195) contained in the scene (190), and (b2) for measuring distances between the sensor system (100) and the at least one object (195) based on a time of flight of the illuminating light (131a, 131b; 331) and the measuring light (196a, 196b); and (c) a data processing device (150) connected downstream of the measuring device (110) for determining a three-dimensional characteristic of the scene (190) based on the measured distances. The lighting device (130a, 130b) has an array of individual light sources (334a) which generates a spatial grid (133) of lighting points (132) in the scene (190). Furthermore, a use of such a sensor system (100) is described for controlling a coverage characteristic of an opening (184) to be passed by an object (195) by at least one closure body (186).

Description

Technical area

The present invention relates to a sensor system and a method for three-dimensional detection of a scene based on time of flight measurements. The present invention also relates to a use of such a sensor system.

Background of the invention

To open and / or close openings or passages, closure bodies operated by means of actuators are often used, which facilitate the handling of the relevant closure body for operators or are operated automatically without any operator action if, for example, an object to be passed through the opening comes into the area of the opening. Such an opening can be a passage in a building, for example. A closing body can be a door, for example.

In order to achieve a high level of operational reliability for closure bodies that can be opened and closed automatically, it is known to use an optical sensor system to detect the area in front of or within an opening that can be covered with a closure body. On the one hand, this can ensure that an object, for example a person, is not accidentally trapped by the closing body when the opening is closed. In addition, in some applications such a sensor system can initiate an automatic opening and / or closing of the closure body or the opening.

Out EP 2 453 252 B1 A 3D sensor system is known for the application area of monitoring automatically opening doors, which is based on the principle of measuring the transit time of light beams emitted by lighting sources and detected by a light receiver after at least partial reflection or 180 ° backscatter. Such sensor systems are generally referred to as “time-of-flight” (TOF) sensor systems. However, TOF sensor systems have the disadvantage that with increasing distance d of the object to be detected, the intensity of the measurement light to be detected (backscattered) by a light receiver of the TOF sensor is weakened in two ways. In the case of a punctiform illuminating light source without special focusing, this attenuation of the illuminating light emitted by the illuminating sources is scaled by 1 / d ^ 2, where d is the distance to the illuminating light source. The same applies to the measuring light if a point on the object at which the illuminating light is isotropically scattered is understood as a point light source. As a result, in this case this leads to a 1 / d ^ 4 scaling of the intensity of the received measurement light. In the case of beam shaping implemented in some way, for example focusing the illuminating light and / or the measuring light in the direction of the light receiver, the intensity attenuation is correspondingly less, but nevertheless contributes to a significant loss of light output. This in turn leads to a correspondingly poor energy efficiency of a TOF sensor system.

Out WO 2018/064745 A1 a system is known for automatically monitoring an opening which can be closed by two sliding doors. Here too, 3D cameras are used, which are based on the TOF principle. A spatial area to be recorded around a movement area of the sliding doors is divided into two sub-areas that are evaluated separately from one another. In a first sub-area, attention is paid to security in order to prevent an object from being trapped by the sliding doors. In the second sub-area, an image evaluation takes place with regard to a different purpose, for example for activating the sliding doors or for counting objects that pass through this second sub-area.

The present invention is based on the object, in particular in the field of the automatic monitoring of openings which can be closed by means of at least one closure body, to enable an efficient and nevertheless reliable three-dimensional detection of a scene from an energetic point of view.

Summary of the invention

This object is achieved by the subjects of the independent claims. Advantageous embodiments of the present invention are described in the dependent claims.

According to a first aspect of the invention, a sensor system for three-dimensional detection of a scene is described. The sensor system described has (a) an illumination device for illuminating the scene with illuminating light; (b) a measuring device (b1) for receiving measuring light which is at least partially back-scattered illumination light from at least one object contained in the scene, and (b2) for measuring distances between the sensor system and the at least one object based on a light transit time of the illumination light and the measuring light; and (c) a data processing device connected downstream of the measuring device for determining a three-dimensional characteristic of the scene based on the measured distances. According to the invention, the lighting device an array of individual light sources, which generates a spatial grid of lighting points in the scene.

The sensor system described is based on the knowledge that the light intensity at the generated illumination points can be particularly high locally through punctual illumination of the scene, without having to provide a strong illumination intensity over the entire scene. As a result, the energy requirement of the lighting device is significantly reduced in comparison to a continuously flat bright illumination when the sensor system is in operation.

The lighting points, which of course only arise when the light rays from the individual light sources strike an object or some other real structure in the scene, lie on a predefined spatial grid, at least in relation to the angle of the individual light rays from the individual light sources emitted by the lighting device. This angle reference means that the light rays of the individual light sources are projected in the scene in such a way that the lighting points in a virtual plane of the scene, which plane is oriented perpendicular to a central optical center axis of the lighting device, form a regular spatial grid of lighting points. This regular spatial grid is distorted by inclined projection surfaces and especially on three-dimensional objects that are in the scene. In the case of moving objects, this distortion changes over time. However, this does not change the fact that the high local illumination intensity leads to strong backscattering behavior at specific points on the surface of objects contained in the scene, so that the measuring device receives a comparatively intense light beam of measuring light from each of the illumination points.

Of course, the spatial resolution of the sensor system described depends on the density or the mean distance between the individual lighting points. However, since in most applications it is not necessary to capture the scene with an extremely high spatial resolution, the use of the array of individual light sources according to the invention can significantly reduce the energy consumption of the sensor system and at the same time ensure that objects in the scene are reliably detected will.

In clear terms, the sensor system according to the invention generates a backscattered measuring light beam which has a comparatively high light intensity for a specific and typically very small solid angle area to be monitored. This also applies if at least one optical component is used which expands the entirety of the light beams of illuminating light emitted by the plurality of individual light sources and / or the entirety of the backscattered light detected by the measuring device from the plurality of illumination points. In any case, a high number of measuring light photons can be accumulated for each resolution pixel of the measuring device compared to a large-area illumination.

In practice, surfaces of objects to be detected are optically mostly of a heterogeneous structure and have locally different backscatter behavior. This means that the objects represent a combination of more and less strongly reflective sub-areas. By using an array of individual light sources as the lighting device, a large number of highly concentrated individual lighting points or small lighting areas can be generated in the respective space segment in an advantageous and simple manner. This increases the probability that at least one of the individual light beams of the illuminating light hits a highly reflective sub-area of an object and is reflected or scattered particularly strongly by it. As a result, a resolution pixel of the sensor system is generated for the measuring device, which due to the high intensity of the received measuring light generates a signal with a high signal-to-noise ratio.

The term “scene” can in particular be understood to mean that spatial area which is evaluated by the sensor system using image processing methods, the scene being recorded in a certain spatial area. Objects in the scene are recognized by suitable image evaluation. For this purpose, known methods for image evaluation and / or image analysis can be used by the data processing device. The data processing device can accordingly be and / or have a special image processing processor, the image processing processor being configured to use or carry out known methods for image evaluation and / or image processing.

In this document, the term “illuminating light” is to be understood as meaning those electromagnetic waves which are emitted by the individual light sources of the illuminating device and strike the relevant at least one object in the scene. The “measuring light” are the electromagnetic waves that are scattered back from or on the object, which are received and received by the measuring device or a light receiver of the measuring device can be used for the three-dimensional evaluation of the scene.

The terms “optical” and / or “light” can refer to electromagnetic waves that have a specific wavelength or frequency or a specific spectrum of wavelengths or frequencies. In particular, the electromagnetic waves used can be assigned to the spectral range that is visible to the human eye. Alternatively or in combination, electromagnetic waves assigned to the ultraviolet (UV) or the infrared (IR) spectral range can also be used. The IR spectral range can extend into the long-wave IR range with wavelengths between 3.5 µm to 15 µm, which can be detected by the light receiver of the sensor.

The term “object” can be understood to mean any three-dimensional physical structure that has a surface quality that leads to at least partial reflection or scattering of illuminating light and is thus visible to the measuring device through the resulting measuring light. The object can be an object such as a motor vehicle or a living being such as a person. The object can be an object that is static or stationary with respect to the sensor system. Furthermore, the object can also move within the scene, leave it or enter it. The movement of the object (according to the law of speed = path / time) can then be determined by repeated scene detection (by comparing the different spatial positions determined with different scene detections). Depending on the application, the absolute value of the speed and / or the motion vector, i.e. additionally the direction of movement can be determined.

The data processing device can be any processor which is configured in a suitable manner by means of a computer program in order to carry out the required tasks. The data processing device can thus be operated by means of software and by means of one or more special electronic circuits, i.e. in hardware. The data processing device can be implemented logically and / or in terms of equipment by means of a common processor or function block or by means of several processors or function blocks. A realization in any hybrid form, i.e. using software components and hardware components is possible.

In this document, the term “array” means any regular spatial arrangement of the individual light sources. In this context, the expression regularly refers to uniform distances between at least some individual light sources that are adjacent to one another. An array is in particular a two-dimensional array in which the individual light sources are arranged within a common plane.

In this document, the term “illumination point” is to be understood in particular as an illumination spot which has a (significantly) smaller spatial extent or dimension compared to the spacing from an adjacent illumination point. The expression “point of illumination is therefore not to be provided in a mathematical sense. The size or, more precisely, the area, in the case of circles the diameter, of an illumination point depends in particular on the divergence of the relevant light beam which generates the illumination point.

According to an exemplary embodiment of the invention, the individual light sources are implemented on a chip. This has the advantage that the plurality of individual light sources can be produced by means of a single (semiconductor) production process. As a result, many hundreds or even thousands of individual light sources can be generated in an efficient manner, so that the scene is illuminated with a correspondingly high number of lighting points. A high number of lighting points means that, given a certain size of the scene to be recorded, the mean distance between adjacent lighting points is correspondingly small and the spatial resolution of the described sensor system is correspondingly large.

Furthermore, by combining the (production of) individual light sources on a chip, differences in brightness between different individual light sources, which are caused by (undesired) tolerances in a separate production of the individual light sources, can be greatly reduced or even eliminated. As a result, individual control of the individual light sources for creating uniform lighting of the scene can be dispensed with in many applications. The described sensor system can thus be manufactured in a cost-effective manner with comparatively few (electronic) components. Since each individual (electronic) component of the sensor system always has a certain energy consumption, the overall energy consumption of the sensor system can be minimized by minimizing the number of components.

According to a further exemplary embodiment of the invention, the individual light sources are arranged essentially in a main plane which is defined by an x-direction and a y-direction perpendicular thereto. Furthermore, at least some of the individual light sources along a z-direction, which is perpendicular to the x-direction and the z-direction, to the main plane a distance of less than 1 millimeter, in particular less than 50 micrometers and further in particular less than 2 micrometers.

Such an only very slight scatter or variation of the positions of the individual light sources along the z-direction, which runs perpendicular to the main plane spanned by the x- and y-directions, enables an optical imaging of the light beams to be realized in a simple and precise manner which are emitted from all or at least from most of the individual light sources. In particular, a (two-dimensional) lens array which is oriented parallel to the main plane and has a multiplicity of microlenses and / or Fresnel lenses can be used for such an optical imaging.

The described spatial arrangement of the individual light sources with high precision, at least along the z-direction, can be implemented, for example, by arranging the individual light sources together on a semiconductor chip by means of semiconductor technology, as described above. Alternatively, the individual light sources can also be arranged as discrete components by means of a high-precision assembly process on a circuit board. This is typically not possible with a conventional SMD assembly process. However, suitable light-emitting chips can be embedded in a circuit board as individual light sources as part of high-precision circuit board production.

It is pointed out that it is not necessary for all of the individual light sources of the array described to have to meet the above condition of an extremely small position tolerance along the z-direction. In many cases it is sufficient if at least some, preferably more than 50%, more preferably more than 80% and even more preferably more than 95% of the individual light sources meet this condition.

According to a further exemplary embodiment of the invention, the individual light sources of the array are arranged within an area of less than 10 cm ^ 2, in particular less than 2 cm ^ 2, further in particular less than 0.8 cm ^ 2. In certain exemplary embodiments, this area is even smaller than 4 μm ^ 2 (= 4 micrometers × micrometers).

The compact spatial arrangement of the individual light sources described has the advantage that the light beams that are emitted by all the individual light sources can be optically precisely shaped and particularly well focused, even with comparatively simple and thus cheap optical components. As a result, comparatively sharp lighting points can be generated, so that the concentration of the lighting energy, which is provided by the entire array of individual light sources, on the lighting points is particularly high.

According to a further exemplary embodiment of the invention, the individual light sources are arranged in the array in such a way that their two-dimensional packing density is higher than in the case of a checkerboard-like arrangement of the individual light sources. This means that the density of the individual light sources as they are arranged within the main plane described above is particularly high. This also contributes to particularly good optical focusability of the illuminating light emitted by the various individual light sources.

In this context, the term “checkerboard-like arrangement” is to be understood as meaning that the positions of the individual light sources are on a square grid. This means that there are both rows of individual light sources along an x-direction and rows of individual light sources along a y-direction perpendicular thereto. In the case of the checkerboard-like arrangement, two adjacent rows in the x direction have no offset along the x direction. They are only spaced from one another along the y-direction. The same applies to adjacent rows in the y-direction, which have no offset along the y-direction but are only spaced apart from one another along the x-direction.

The increase in the two-dimensional packing density described here can be achieved by providing a specific offset along the x direction with respect to two rows along the x direction, so that these “x rows” move closer to one another along the y direction can. This “moving closer together” is possible because the individual light sources (in a plan view) typically do not have a purely square shape. The shape can be at least approximately circular, for example. The two “x-rows” can usually have a minimum distance from one another along the y-direction if the offset is exactly half the “x-distance” between two adjacent individual light sources of the respective “x-row”. The same naturally also applies to the “y rows” along the y direction.

According to a further exemplary embodiment of the invention, the sensor system furthermore has an illumination light control device which is information technology-related to the illumination device and which is configured to individually control individual illumination light sources or individual groups of illumination light sources of the array of individual light sources. This has the The advantage that a dynamic and / or situation-adaptive adaptation of the scene lighting can be carried out.

Each individual light source, possibly together with one or more other individual light sources, is preferably assigned to a specific solid angle area of the scene. Then, for example, individual sub-areas of the scene can be illuminated with different levels of brightness. For example, when the described sensor system is used to control a coverage characteristic of an opening to be passed by an object through at least one closure body, a security-relevant sub-area can be illuminated more brightly than a sub-area which is only relevant for activation (a movement) of the closure body. The security-relevant sub-area can be that area in the scene which is assigned to the immediate movement of the closure body, so that objects located in this sub-area potentially collide with the moving closure body and possibly become trapped.

In this context it is pointed out that two different types of sensors are typically used in conventional systems for the two tasks “security” in the security-relevant sub-area and the task “activation” in a sub-area somewhat further away from the closure body. For example, radar sensors, 3D sensors or thermal imaging cameras are used for the “activation” task. For example, contact strips or light barriers are used for the task of "security". In contrast to this, in the solution described here, a single type of 3D sensor is used to record both partial areas. This means that the tasks of "security" and "activation" are not performed by two different types of sensors. This represents a further advantage in terms of the lowest possible energy consumption.

According to a further exemplary embodiment of the invention, the illuminating light control device is information-technically coupled to the data processing device. Furthermore, the data processing device is set up in terms of programming to cause the lighting control device to switch from a first lighting operating mode to the second lighting operating mode when at least part of an object is detected.

In the second lighting operating mode, at least a partial area of the scene can be illuminated more brightly than in the first lighting operating mode. This means that the energy requirement of the lighting device and thus of the entire sensor system is lower in the first lighting operating mode than in the second lighting operating mode. The first lighting operating mode can be activated, for example, in an idle state or in a stand-by operating state of the sensor system, in which the scene is only monitored with a very low level of accuracy and consequently only a comparatively weak or less intensive illumination of at least a partial area the scene is required.

In this exemplary embodiment, an improved lighting situation can advantageously be produced after at least partial object detection, so that the object in question can be detected more precisely and / or more completely with a subsequent detection.

Of course, at least one third lighting operating mode can also be provided, so that the most optimal scene lighting possible can be implemented for different characteristics of the scene, depending on the situation. For setting such an optimal scene lighting, a weighting can be made between energetic aspects (bright lighting requires more electrical energy) and the need for lighting that is as bright as possible for the purpose of reliable object detection.

According to a further exemplary embodiment of the invention, the first lighting operating mode is assigned an illumination of a first partial area of the scene and the second lighting operating mode is assigned an illumination of a second partial area of the scene.

Different recognition tasks can be assigned to the two sub-areas. As already described above, when controlling a closure body, one sub-area can be a security-relevant sub-area (safety area) and the other sub-area can be a so-called activation area, which is used for activating the wearing body, in particular for moving the wearing body from a closed position to an open position , is taken into account if an object is detected in this activation area.

A first number of the individual light sources are preferably assigned to the first partial area and a second number of the individual light sources are assigned to the second partial area. In particular in applications in which a sub-area is a safety-relevant sub-area of the scene, this has the advantage that a clear optical illumination boundary is achieved between the two sub-areas can be. For example, energy can be saved for illuminating the scene outside of this security area or outside a closing edge or a closing line of a closing body by illuminating this "outside partial area" only very weakly or, in extreme cases (at least at certain times), not at all .

Depending on the specific application, the sub-areas can be spatially different or separated from one another or the sub-areas can overlap. A sub-area can also completely enclose the other sub-area.

The lighting in the different sub-areas or in the different lighting operating modes can differ in particular in terms of the light intensity. Alternatively or in combination, other characteristic light properties such as different wavelengths and / or different polarization properties can also be assigned to the different lighting operating modes. A selection of the wavelength can be implemented by means of suitable wavelength-dependent filters. The polarization can be selected by means of suitable polarizers or polarization-sensitive filters.

The described division of the scene into different sub-areas can also take place dynamically, for example as a function of an intermediate “pre-detection” of an object or the operating state of an external component, for example a closure body for an opening. The dynamic division can go so far that in one of the two lighting operating modes the size of a partial area is zero. This means that there is then no spatial division into (at least) two sub-areas. Such a “shrinkage to size zero” can be useful, for example, when the closure body is at rest, preferably in its closed position. Then there is no need to worry about a collision with an object because the closing body can only move in the direction of its opening position. In the other of the two operating modes, in the exemplary embodiment described here, the entire spatial area is divided into (at least) two partial areas.

According to a further exemplary embodiment of the invention, the individual light sources are lasers, in particular VCSELs.

By realizing the array by means of (semiconductor) laser light sources, a laser system is available as an illumination source which, due to the coherence of the emitted laser light, leads to the formation of so-called speckle patterns. These speckle patterns can be used by a light detector of the measuring device to improve the accumulation of photons and thus to increase the sensitivity of the TOF measurement.

Such a formation of speckles leads to a pseudo-random pattern of lighter and darker zones on the light detector. When using several arrays of individual light sources and a corresponding number of light detectors, when several such speckle patterns are superimposed in the scene, first locations are created at which a first array of individual light sources is dominantly illuminated and to which a first measuring light is assigned, which is a second light detector ensures increased photon accumulation. Furthermore, second locations arise in the scene at which a second array of individual light sources is illuminated dominantly and to which a second measurement light is assigned, which ensures increased photon accumulation at corresponding locations of a second light detector.

When several combinations of individual light source arrays and light detectors are used, the pseudo-random local distribution of these speckle patterns results in a locally pseudo-random distribution of the locations to which increased photon accumulation is assigned. As a result, the described sensor system achieves increased measurement accuracy and / or increased sensitivity with an improved signal-to-noise ratio at these pseudo-randomly distributed locations. Different light frequencies can preferably be used for illuminating the scene with different individual light source arrays. Then, with a corresponding filtering of the spectrally different measurement light, a clear association between illumination light and measurement light can take place. A “crosstalk” between different combinations of individual light source arrays and the associated light detector can be prevented or at least greatly reduced by such a “frequency multiplex principle”. Alternatively or in combination, a time discrimination between a first pulsed illumination of the scene by the first single light source array and a second pulsed illumination of the scene by the second single light source array and a correspondingly time-shifted measurement light detection by the first light detector or the second light detector ("time multiplex principle"). An association between the individual light source array and light detector can also be made by temporally modulating the (transmit-side) illuminating light with a predetermined modulation frequency and a corresponding (receive-side) signal filtering of the measurement signals of the respective light detector, with only those (receive-side) signal filtering Signal components are evaluated which occur with the predetermined modulation frequency (so-called lock-in principle).

According to a further exemplary embodiment of the invention, the individual light sources are set up to generate illuminating light in the infrared spectral range. As a result, illuminating light with a relatively high light intensity can be generated with a relatively low energy consumption. This applies in particular when the individual light sources are semiconductor individual light sources such as semiconductor lasers or light-emitting diodes.

Another advantage of using infrared illuminating light in many applications can be that it cannot be perceived by humans (and many animals). This means that people are not disturbed by a possibly pulsed illumination light.

According to a further embodiment of the invention. Sensor system according to one of the preceding claims, wherein
the lighting device has at least one further array of individual light sources, which generates a further illuminating light that generates a further spatial grid of lighting points in the scene. In this case, the scene is illuminated with at least one further illuminating light, so that overall an increased intensity of illuminating light can be generated.

According to a further exemplary embodiment of the invention, the array is assigned to a sub-region of the scene and the further array is assigned to a further sub-region of the scene. The two sub-regions are different and have a certain spatial overlap. This has the advantage that a so-called “multi-sensor” sensor system can be implemented in a simple manner, with particularly reliable scene detection being possible in the overlapping area due to the redundancy of the lighting.

In some exemplary embodiments, the measuring device has two light receivers, preferably embodied as semiconductor chips, with one light receiver being assigned to the array and a further light receiver being assigned to the further array. The assignment can be designed in such a way that, apart from any undesirable crosstalk between (i) a measuring channel with the array and the light receiver and (ii) a further measuring channel with the further array and the further light receiver, the illuminating light from the array only from the Light receiver and the (further) illuminating light from the further array is received only by the further light receiver.

According to a further exemplary embodiment of the invention, the array of individual light sources illuminates the scene from a first direction and the further array of individual light sources illuminates the scene from a second direction. The second direction is different from the first direction. This has the advantage that undesired shadowing effects in the scene can at least be reduced when detecting spatially offset objects. A more complete scene capture can thereby be realized.

In a particularly advantageous manner, shadowing effects can be reduced if the measuring device has a light detector and at least one further light detector so that, as described above, exactly one light detector is assigned to each array of individual light sources. The spatial arrangement of the light detectors can be adapted to the spatial arrangement of the arrays of individual light sources in such a way that shadowing effects can also be reduced in relation to the respective measurement light. Furthermore, through a suitable arrangement of the light detectors in relation to the respective array of individual light sources, it can be achieved that the intensity of the measurement light generated by anisotropic scattering is as high as possible.

According to a further exemplary embodiment of the invention, the further spatial grid of lighting points in the scene is spatially offset from the spatial grid of lighting points.

Such a spatial offset of the spatial grids of illumination points generated by different arrays of individual light sources can improve or increase the spatial resolution of the sensor system in a simple and efficient manner. Such an offset can also be referred to as “spatial interleaving”.

According to a further exemplary embodiment of the invention, when the sensor system is in operation, the array of individual light sources generates the illuminating light with a predetermined modulation frequency. Furthermore, the further array of individual light sources generates the further illumination light with a further predetermined modulation frequency, which is different from the predetermined modulation frequency. As a result, the illumination light generated by different arrays of individual light sources can be differentiated on the basis of different modulation frequencies. By using a corresponding filter on the receiver side of the respective scattered measurement light, this enables a distinction according to the so-called lock-in principle, from which illumination light the measurement light received in each case is scattered at one Object surface was created. This “lock-in assignment” can be used in an advantageous manner in particular when the illumination angles of the illumination light and additional illumination light are different. Information about the scattering angle can then also be obtained. In this way, information about the orientation of partial areas of surfaces of objects located in the scene can be obtained according to the principle of stereometry. This is most easily evident in the case of at least partially reflective surfaces, where there is less light scattering than light reflection with the condition “angle of incidence equals angle of reflection”.

According to a further exemplary embodiment of the invention, the data processing device is configured in such a way that a coverage characteristic of an opening can be controlled by at least one closure body.

With the sensor system described, the opening, which is, for example, an entrance (or an exit) of a building, can be automatically monitored in an energetically favorable manner. By suitably controlling an actuator, the closing body can be moved automatically between an open position (open position) and a closed position (closed position) or vice versa. For this purpose, the data processing device of the sensor system described can be coupled to the control of a known control system for a closure body.

The wear body can be any desired barrier element by means of which an opening can be temporarily at least partially closed. The closing body can be, for example, (i) a sliding door, (ii) a revolving door, (iii) a turnstile, (iv) a gate, in particular a garage door, (v) a barrier, in particular at a level crossing or a vehicle entrance or exit.

According to a further exemplary embodiment of the invention, the data processing device has a data input for receiving an input signal which is indicative of a current operating state of the closure body. Furthermore, the data processing device is configured to control the lighting device based on the current operating state of the closure body.

The lighting device can be controlled by the lighting light control device described above. In particular, the illuminating light control device can control the illuminating device in such a way that it has a first energy consumption in a first operating mode and a second energy consumption in a second operating mode, which is smaller than the first energy consumption.

Expressed clearly, the described at least one array of individual light sources enables individual control of each individual light source with suitable “wiring” of the electrical connections. This can in particular be used to the effect that, depending on the specific operating state of the closure body, individual of these sources can be switched off. For example, when the door is open, as long as there is an object in the security area of the door, the intensity of the lighting in a far zone (activation area) can be reduced or the lighting in this far zone can be switched off completely because during this time the for reasons of Security required keeping the closing body open, no additional activation of the closing body is necessary or useful.

Due to the dependency (of the intensity) of the lighting, the energy consumption of a 3D sensor (system), which energy consumption is typically significantly greater than that of a 2D sensor, can be significantly reduced in a simple manner by the fact that this 3D sensor or the 3D sensor system always is then operated in an "energy saving mode" if the requirements for scene monitoring are not so great. This is the case with a 3D sensor that is used to monitor an opening that can be closed by a closure body, for example when the closure body is at rest or when it is moved in the direction of an opening position. This is because the risk that an object, in particular a person who is located in a movement area of the closure body, will be trapped by the closure body is not present or at least significantly reduced.

The operating state of the closing body can be a state of movement and in particular can be determined by whether the closing body moves in the direction of its opening position or its closing position. The speed at which the closure body moves can also characterize the state of movement. Furthermore, the operating state can also depend on the current position of the closure body, this position being a rest position or a current position over which the closure body is currently moving.

The operating mode of the lighting device and / or possibly also an operating mode of the measuring device can be any type of operating mode that reduces the energy consumption of the entire Sensor system (with) determined. The energy consumption can relate to the lighting device and possibly also to the measuring device.

According to a further aspect of the invention, a method is described for three-dimensional detection of a scene by means of a sensor system and in particular by means of a sensor system of the type described above. The method described has (a) illuminating the scene with illuminating light which is emitted by an illuminating device; (b) receiving measuring light, which is at least partially backscattered illumination light from at least one object contained in the scene, by means of a measuring device; (c) a measurement of distances between the sensor system and the at least one object based on a light transit time of the illuminating light and the measuring light by means of the measuring device; and (d) determining a three-dimensional characteristic of the scene based on the measured distances by means of a data processing device connected downstream of the measuring device. According to the invention, the lighting is carried out by means of an array of individual light sources which generates a spatial grid of lighting points in the scene.

The method described is also based on the knowledge that, through a spatial concentration of the light intensity available with a certain energy consumption, an illumination intensity given locally at the illumination points generated can be particularly high. As a result, the scene can be recorded at these points with a high signal-to-noise ratio and thus a high measurement or detection accuracy can be achieved for objects present in the scene.

According to one exemplary embodiment of the invention, the method further comprises (a) detecting an object located in the scene; (b) a comparison of the detected object with at least one comparison object stored in a database; and, (c) if the object matches a comparison object within predetermined permissible deviations, identifying the object as an object permitted for a specific action.

The permitted action can be, for example, permitted passage through an opening in a building, which opening is closed by a closure body before the identified object is identified as an permitted object and is only opened after successful identification by a corresponding movement of the closure body. The objects to be identified can preferably be people and / or vehicles. Successful identification can be for controlling or activating a locking mechanism for a locking body in front of an opening of a building. If (by means of a suitable image evaluation) no approximate correspondence is established between a recognized object and the description of a comparison object, then the closure body cannot be activated. The closing body then remains in its closed position.

According to a further aspect of the invention, a use of a sensor system of the type described above for controlling a covering characteristic of an opening to be passed by an object by at least one closure body is described.

The described use is based on the knowledge that by designing a lighting device as an array of individual light sources, the scene at the spatial grid of lighting points can be illuminated with a comparatively intense lighting light in an energetically efficient manner. Due to the locally high intensity, the scene at the raster points can be recorded or characterized with a high signal-to-noise ratio and thus with a high level of measurement accuracy.

The inventive use of the sensor system described above with locally very bright lighting points enables even larger distances to be monitored in an energetically efficient manner, which naturally leads to an earlier detection of an opening request of the closure body. This can be of great advantage, especially with fast moving objects. Furthermore, the scene can be captured with a wider capture angle, which, for example, can lead to an early detection of cross traffic moving across the opening and thus to a more reliable detection of objects in a hazard area.

According to an exemplary embodiment of the invention, the opening is an entrance or an exit, in particular an emergency exit in a building. By recognizing an existing but possibly not moving object in a passage area, an entrance or exit can be monitored, in particular a blocked emergency exit, and the corresponding information transmitted to an associated system, for example a monitoring system.

According to a further exemplary embodiment of the invention, the object is a person or a vehicle. In this case, the building can in particular be a house or a garage.

It should be noted that embodiments of the invention have been described with reference to different subjects of the invention. In particular, some embodiments of the invention are described with device claims and other embodiments of the invention are described with method and use claims. However, when reading this application, it will immediately become clear to the person skilled in the art that, unless explicitly stated otherwise, in addition to a combination of features belonging to one type of subject matter of the invention, any combination of features belonging to different types of Subjects of the invention belong.

Further advantages and features of the present invention emerge from the following exemplary description of currently preferred embodiments.

Figure list

• 1 shows the use of a sensor system for controlling a covering characteristic of an opening by means of closing bodies designed as sliding doors.
• 2 shows an array of individual light sources formed from VCSELs, which are implemented on a semiconductor chip.

Detailed description

1 shows the use of a sensor system 100 for controlling a covering characteristic of an opening 184 depending on the characteristics of one of the sensor system 100 monitored scene 190 . According to the embodiment shown here, the opening is 184 an entrance opening for people into a building or a garage entrance for motor vehicles. The corresponding input structure is given the reference number 180 Mistake. An object in the scene 195 is intended to symbolize such a person or a motor vehicle.

The entrance structure 180 includes a stationary support structure 182 , which has a frame and a guide for two closing bodies designed as sliding doors 186 represents. The sliding doors 186 can each by means of a motor 187 be moved along the displacement directions shown by two thick double arrows. The control of the motors 187 takes place, as set out below, by means of a data processing device 150 of the sensor system described in this document 100 .

According to the embodiment shown here, an operating state of the two sliding doors 186 by means of an encoder each 188 recorded which compared to the respective engine 187 represents a separate entity. In other embodiments, the encoder can also be in the respective motor 187 be integrated. In addition, the function of the encoder can also be performed by the data processing device 150 be taken over.

The operating state of the sliding doors 186 can see the current position of the sliding doors 186 and / or the current speed at which the sliding doors are moving 186 move from an open position to a closed position or vice versa from the closed position to the open position.

The sensor system 100 indicates a Time Of Flight (TOF) measuring device 110 , the data processing facility 150 as well as a database 160 .

The TOF measuring device 110 in turn has a lighting device and a light receiving device. According to the exemplary embodiment shown here, the lighting device has two lighting units, a first lighting unit 130a and a second lighting unit 130b on. The light receiving device has two light receivers, a first light receiver 120a and a second light receiver 120b on.

According to the exemplary embodiment shown here, the TOF measuring device 110 on or are the TOF measuring device 110 assigned (i) an illumination light control device 135 to control the operation of the two lighting units 130a , 130b , (ii) one of the two light receivers 120a , 120b downstream measuring unit 125 for measuring a time of flight between the respective lighting unit 130a or. 130b emitted illuminating light 131a or. 131b and from the respective light receiver 120a or. 120b after scattering on the object 195 received measurement light 196a or. 196b and (iii) a light receiver controller 140 to control the operation or to select an operating mode for the respective light receiver 120a , 120b .

For the two light receivers, a second operating mode with lower energy consumption can consist in that not all pixels of the relevant sensor chip are activated. This results in a reduced spatial resolution. Alternatively or in combination, a repetition rate of temporally successive image acquisitions can be reduced. This results in a reduced temporal resolution of the scene detection.

According to the embodiment shown here is the first light receiver 120a the first lighting unit 130a assigned. This means that the first light receiver 120a in relation to the first lighting unit 130a is arranged and configured and is further operated such that the first light receiver 120a that measuring light 196a receives which by scattering or reflection from the illuminating light 131a on the object 195 is produced. The second light receiver is in a corresponding manner 120a the second lighting unit 130b assigned. In other exemplary embodiments, there is no such fixed assignment. This means that both light receivers 120a and 120b all available measuring light 196a and 196b receive (can).

The two lighting unit 130a and 130b are each implemented as an array of individual light sources which are formed on a semiconductor chip. Each individual light source is formed by a surface emitter or VCSEL (Vertical Cavity Surface Emitting Laser). The individual, spatially discrete light rays of the illuminating light 131a , 131b create a spatial grid in the scene or, more precisely, on projection surfaces of the scene 133 of lighting points 132 . For the sake of clarity, the 1 only one light beam of the illuminating light at a time 131a or. 131b as well as only the light rays of the associated measuring light 196a or. 196b drawn. Furthermore, for the sake of clarity, not all of the lighting points are included 132 of the two from the lighting units 130a and 130b generated grid of lighting points 132 shown.

According to the exemplary embodiment shown here, the TOF measuring device 110 all optical components of the sensor system 100 housed. The entire sensor system is preferred 100 (in contrast to the representation of 1 ) constructed as a module, which in a compact design in addition to the TOF measuring device 110 also the data processing device 150 as well as the database 160 having.

The data processing device controls the operation of the sensor system 150 the two engines 187 . The electrical power required to operate the doors 186 is provided in each case by an output stage or an amplifier which, according to the exemplary embodiment shown here, is in the housing of the respective motor 187 is integrated. The two output stages are each controlled by a signal 152a , which at a data output 152 from the data processing and control device 150 is output and therefore in this document as an output signal 152a referred to as.

According to the embodiment shown here, the operating state of the doors 186 at least some influence on the operation of the TOF measuring device 110 . Specifically, this operating state determines the operation of the lighting units 130a and 130b and optionally also the operation of the two light receivers 120a and 120b (With). This influence manifests itself in two operating modes of the TOF measuring device 110 . In a first operating mode, the sensor system 100 and especially the TOF measuring device 110 and further in particular the lighting units 130a and 130b an initial energy consumption. In a second operating mode, these components have a second energy consumption that is lower than the first energy consumption.

The first operating mode is activated when the scene is to be captured with greater accuracy. This is the case, for example, when a person is near the open sliding doors 186 and it must be ensured that this person 195 not from closing sliding doors 186 is pinched. Possibly. needs a closing movement of the sliding doors 186 Quit immediately when that person turns 195 further in the direction of the danger area of the sliding doors 186 emotional. This requires not only rapid but also reliable recognition of the position and / or speed of this person 195 , which according to the embodiment shown here is only possible when the illuminating light 130a , 130b is particularly strong.

The second operating mode is activated when the scene is sufficient 190 with less accuracy. This is the case, for example, when there is no person in the scene 190 or if there is a person 195 although in the scene 190 is located, but this person is still far from the danger area of the sliding doors 186 away. Then there is at least a short-term collision of the person 195 with the sliding doors 186 to get. The second operating mode can differ from the first operating mode in that pulsed lighting is carried out with a lower repetition rate, so that the sensor system 100 has a reduced temporal resolution. Alternatively or in combination, not all of the individual light sources can be controlled in the second operating mode, so that at least some individual light sources, for example every second individual light source, do not light up. This determines the (mean) distances between neighboring lighting points 132 increased, which results in a lower spatial resolution of the sensor system 100 leads.

The operating state of the sliding doors described above 186 is by means of a Data signal or a sequence of data signals from the two encoders 188 to one data input each 151 the data processing device 150 transmitted. This data signal is also used as an input signal in this document - from the point of view of the data processing device 150 151a designated. According to the embodiment shown here, the data processing device processes 150 this input signal 151a in a suitable way and controls, among other things depending on this input signal 151a , the illumination light controller 135 and optionally also the light receiver control device 140 in such a way that an operating mode is set that reduces the energy consumption of the two lighting units 130a , 130b and optionally also the operating mode of the two light receivers 120a , 120b (with) determined.

The dependency of the operating mode, in particular of the two lighting units 130a , 130b the operating status of the two sliding doors 186 According to the exemplary embodiment shown here, the first operating mode with the higher energy consumption is activated when the two sliding doors 186 are moved, in particular from their open position to their closed position. The second operating mode with the lower energy consumption is activated when the two sliding doors 186 are at rest.

The scene 190 is detected by the sensor system in a spatial area, which is a first partial area 191 and a second sub-area 192 includes. The first part 191 is a so-called hazard area. As already mentioned above, if there is an object in this hazardous area 191 there is always the risk of this when the doors close 186 pinched and possibly injured. Hence the sensor system 100 configured in this way, this hazardous area 191 basically to be recorded with a very high accuracy. For this purpose, in the first operating mode described above, this hazardous area is illuminated appropriately brightly 191 and detection with high accuracy is required. In this context, it is obvious that this requires a relatively large amount of energy. When the doors open 186 but do not move, then there is no risk of trapping or injuring an object. It is therefore completely sufficient in a second operating mode if the hazardous area 191 from the lighting units 130a , 130b illuminated with a lower intensity and / or when the light receiver 120a , 120b the hazard area 191 record with a reduced accuracy.

According to the embodiment shown here is the second sub-area 192 an area where objects are detected so the doors 186 moved in a suitable manner. The second part 192 is therefore used in this document as the activation area 192 designated. The activation area 192 is usually not relevant to safety (in relation to a door collision 186 with an object 195 ). Therefore the activation area becomes 192 in the embodiment described here, regardless of the operating state of the doors 186 only monitored in such a way that the best possible energy efficiency is given at the expense of the accuracy of the scene detection.

According to the embodiment shown here, the sensor system 100 able to detect objects. The data processing device intervenes for this purpose 150 on one in the database 160 stored data record of reference objects, which correspond to selected objects that are authorized to open 184 to happen. This means that with a suitable approach of the object 195 to the entrance 184 the sliding doors 186 can only be opened when the detected object 195 at least approximately corresponds to one of the stored reference objects. This clearly means that when using the sensor system described here 100 an object-based access control takes place.

2 shows an array of individual light sources formed from VCSEL 334a that are on a semiconductor chip 334 are realized. Each of these individual light sources 334a creates a beam of illuminating light 331 , which has a certain divergence or widening due to unavoidable diffraction effects due to the optical limitations of the respective VCSEL resonator, which in 2 each illustrated by a cone of light. The optical axes of the light cones are in 2 illustrated by an arrow each.

It is noted that the term “having” does not exclude other elements and that the “a” does not exclude a plurality. Elements that are described in connection with different exemplary embodiments can also be combined. It should also be noted that any reference signs in the claims should not be construed as limiting the scope of the claims.

List of reference symbols

100

Sensor system

110

TOF measuring device

120a

Light receiving device / first light receiver

120b

Light receiving device / second light receiver

125

Measuring unit

130a

Lighting device / first lighting unit

130b

Lighting device / second lighting unit

131a

Illuminating light

131b

Illuminating light

132

Lighting points

133

Grid

135

Illumination light control device

140

Light receiver control device

150

Data processing device

151

Data input

151a

Input signal

152

Data output

152a

Output signal

160

Database

180

Entrance structure

182

stationary support structure

184

opening

186

Closing body / sliding door

187

Motor M

188

Encoder E

190

scene

191

first part

192

second part

195

object

196a

Measuring light

196b

Measuring light

331

Illuminating light

334

chip

334a

Single light sources

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• EP 2453252 B1 [0004]
• WO 2018/064745 A1 [0005]

Claims (22)

Sensor system (100) for three-dimensional detection of a scene (190), comprising the sensor system (100) an illuminating device (130a, 130b) for illuminating the scene (190) with illuminating light (131a, 131b; 331); a measuring device (110) for receiving measurement light (196a, 196b) which is at least partially backscattered illumination light (131a, 131b; 331) from at least one object (195) contained in the scene (190), and for measuring distances between the sensor system (100) and the at least one object (195) based on a light transit time of the illuminating light (131a, 131b; 331) and the measuring light (196a, 196b); and a data processing device (150) connected downstream of the measuring device (110) for determining a three-dimensional characteristic of the scene (190) based on the measured distances; wherein the lighting device (130a, 130b) has an array of individual light sources (334a) which generates a spatial grid (133) of lighting points (132) in the scene (190). Sensor system (100) according to the preceding claim, wherein the individual light sources (334a) are implemented on a chip (334). Sensor system (100) according to one of the preceding claims, wherein the individual light sources (334a) are arranged essentially in a main plane which is defined by an x-direction and a y-direction perpendicular thereto, and wherein at least some of the individual light sources (334a) are along a z-direction, which is perpendicular to the x-direction and the z-direction, are at a distance from the main plane of less than 1 mm, in particular less than 50 μm and further in particular less than 2 μm. Sensor system (100) according to one of the preceding claims, wherein the individual light sources of the array are arranged within an area of less than 10 cm ^ 2, in particular less than 2 cm ^ 2, further in particular less than 0.8 cm ^ 2. In certain exemplary embodiments, this area is even smaller than 4 μm ^ 2. Sensor system (100) according to one of the preceding claims, wherein the individual light sources are arranged in the array in such a way that their two-dimensional packing density is higher than in the case of a checkerboard arrangement of the individual light sources. Sensor system (100) according to one of the preceding claims, further comprising an illumination light control device (135) which is information technology coupled to the illumination device (130a, 130b) and which is configured, individual illumination light sources (334a) or individual groups of illumination light sources (334a) of the Controlling arrays of single light sources (334a) individually. The sensor system (100) according to the preceding claim, wherein the illumination light control device (135) is IT-coupled to the data processing device (150) and the data processing device (150) is set up in terms of programming, the illumination light control device when at least part of an object (195) is detected To cause (135) to switch from a first lighting operating mode to the second lighting operating mode. Sensor system (100) according to the preceding claim, wherein the first lighting operating mode is assigned an illumination of a first sub-area (191) of the scene (190) and the second lighting operating mode is assigned an illumination of a second sub-area (192) of the scene (190) is. Sensor system (100) according to one of the preceding claims, wherein the individual light sources (334a) are lasers, in particular VCSELs. Sensor system (100) according to one of the preceding claims, wherein the individual light sources (334a) are set up to generate illuminating light (131a, 131b) in the infrared spectral range. Sensor system (100) according to one of the preceding claims, wherein the lighting device has at least one further array (130b) of individual light sources (334a), which generates a further illuminating light (131b) that forms a further spatial grid (133) in the scene (190). generated by lighting points (132). The sensor system (100) according to the preceding claim, wherein the array is assigned to a partial region of the scene and the further array is assigned to a further partial region of the scene, the two partial regions being different but spatially overlapping. Sensor system (100) according to one of the two preceding claims, wherein the array of individual light sources illuminates the scene from a first direction and the further array of individual light sources illuminates the scene from a second direction, the second direction being different from the first direction. Sensor system (100) according to one of the three preceding claims, wherein in the scene (190) the further spatial grid of lighting points is spatially offset from the spatial grid of lighting points. Sensor system (100) according to one of the four preceding claims, wherein in operation the array (130a) of individual light sources (334a) generates the illumination light (131a) with a predetermined modulation frequency and the further array (130b) of individual light sources (334a) generates the further illuminating light (131b) with a further predetermined modulation frequency which is different from the predetermined modulation frequency. Sensor system (100) according to one of the preceding claims, wherein the data processing device (150) is configured in such a way that a coverage characteristic of an opening (184) can be controlled by at least one closure body (186). Sensor system (100) according to the preceding claim, wherein the data processing device (150) has a data input (151) for receiving an input signal (151a) which is indicative of a current operating state of the closure body (186), and the data processing device (150) is configured to control the lighting device (130a, 130b) based on the current operating state of the closure body (186). A method for three-dimensional detection of a scene (190) by means of a sensor system (100), in particular by means of a sensor system (100) according to one of the preceding claims, having the method Illuminating the scene (190) with illuminating light (131a, 131b) which is emitted by an illuminating device (130a, 130b); Receiving measuring light (196a, 196b), which is at least partially backscattered illumination light (131a, 131b) from at least one object (195) contained in the scene (190), by means of a measuring device (110); Measuring distances between the sensor system (100) and the at least one object (195) based on a light transit time of the illuminating light (131y, 131b) and the measuring light (196a, 196b) by means of the measuring device (110); and Determining a three-dimensional characteristic of the scene (190) based on the measured distances by means of a data processing device (150) connected downstream of the measuring device (110); wherein the illumination is carried out by means of an array of individual light sources (334a), which generates a spatial grid (133) of illumination points (132) in the scene (190). A method according to the preceding claim, further comprising Detecting an object (195) located in the scene (190); Comparing the detected object (195) with at least one comparison object stored in a database (160); and, if the object (195) matches a comparison object within predetermined permissible deviations, identifying the object (195) as an object (195) that is permitted for a specific action. Use of a sensor system (100) according to one of the preceding Claims 1 to 17th for controlling a coverage characteristic of an opening (184) to be passed by an object (195) by at least one closure body (186). Use according to the preceding claim, wherein the opening (184) is an entrance or an exit, in particular an emergency exit in a building. Use according to one of the two preceding claims, wherein the object (195) is a person or a vehicle.

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