DE102015115101A1 - Sensor system of a sensor device of a motor vehicle - Google Patents

Abstract

In a sensor system (3) of a sensor device (4) of a motor vehicle (1) for the optical detection of objects and their spatial movements, comprising a 3D camera that detects spatial data with a transit time method and the light source (6) and a light-sensitive receiving device (7), wherein the light source (6) and the light-intensive receiving device (7) can be arranged in a common sensor housing (5) and both are aligned to a detection area (8) of the 3D camera, a solution is to be provided ensures homogeneous illumination of the detection range of the 3D camera. This is achieved in that the light source (6) has a transmitting optics (21) for the predetermined dispersion of the emitted light, wherein the transmitting optics (21) a first lens (22) and a second lens (23) in the direction of the emitted light is arranged behind the first lens (22), wherein at least one boundary surface (33) of at least one of the two lenses (22, 23) is formed as a free-form surface (32).

Description

The invention is directed to a sensor system of a sensor device of a motor vehicle for the optical detection of objects and their spatial movements, comprising a 3D camera, which records spatial data with a transit time method and which comprises a light source and a light-sensitive receiving device, wherein the light source and the light-intensive Receiving device can be arranged in a common sensor housing and both are aligned to a detection range of the 3D camera.

Such a sensor system with such a sensor device is recently used for optically supported detection of operating gestures or operations on motor vehicles. In this case, temporally and spatially resolved information is recorded and evaluated in order to recognize the user's will to operate in the form of his gesture or action.

In the prior art, optical methods are known which detect actuations in response to an evaluation of image information and then trigger switching operations, for example. By way of example, automatic video evaluations of surveillance systems can be mentioned here, which read out patterns or movements from individual images or a sequence of images. In addition, many other optically-based systems are known, with the most basic systems including, for example, light barriers or brightness sensors. However, optical systems of higher complexity often use an array of optically sensitive detection units, usually referred to as pixels, which receive optical information in parallel, for example in the form of a CCD array.

The DE 10 2008 025 669 A1 discloses an optical sensor which detects a gesture, whereupon a closure member of a vehicle is automatically moved.

The WO 2008/116699 A2 relates to an optical sensor chip and relates to an optical anti-jamming device for monitoring a windowpane, sliding door or tailgate in a motor vehicle.

The WO 2012/084222 A1 discloses an optical sensor for operating and monitoring a closure element.

As the gesture control in various technical areas is becoming increasingly accepted, attempts have also been made to use such purely optical systems for detecting the desire to operate in motor vehicles. However, these systems continue to have control over capacitive systems.

In the field of optical detection systems are known which detect a pixel-related location information, in particular a distance from the sensor or detection device. The WO 2013/001084 A1 discloses a system for non-contact detection of objects and operating gestures with an optically-based device of a similar type as is also applicable to the sensor system of the present invention.

These systems are called, for example, depending on the applied evaluation method, as a "time-of-flight" systems or as a "3D Imager" or "Range Imager". The fields of application of such systems are in the field of industrial automation technology, in safety technology and in the automotive sector. In a car, 3D sensors are used in lane keeping systems, for pedestrian protection or as a parking aid. Both concepts of triangulation and of interferometry and time-of-flight (ToF) can be implemented with optical sensors.

In this connection reference is made to relevant elaborations which describe the technical concepts and their realization in detail, in particular the dissertation "Photodetectors and Readout Concepts for 3D Time of Flight Image Sensors in 0.35 μm Standard CMOS Technology", Andreas Spickermann, Faculty of Engineering, University of Duisburg-Essen, 2010 ,

Also, on the publication Bernhard König, Faculty of Engineering, University of Duisburg-Essen, 2008 "Optimized Distance Measurement with 3D-CMOS Image Sensor and Real-Time Processing of the 3D Data for Applications in Automotive and Safety Engineering" directed.

The above-mentioned works describe the concept and the realization of deployable optical sensor systems, so that in the context of this application reference is made to their disclosure and only relevant to understanding the application relevant aspects are explained.

The invention relates to a sensor system and a sensor arrangement, which uses the time-of-flight (ToF) method, so that this will be briefly explained here.

In the ToF method, a room area is illuminated with a light source and the runtime of the light reflected back from an object in the spatial area is recorded with an area sensor. For this purpose, the light source and sensor should be arranged as close as possible to each other. The distance between the sensor and the object to be measured can be determined from the linear relationship between the light transit time and the speed of light. To measure the time delay, there must be a synchronization between the light source and the sensor. By using pulsed light sources, the processes can be optimized, because short light pulses (in the ns range) enable efficient background light suppression. In addition, the use of the pulsed light avoids possible ambiguities in determining the distance as long as the distance is sufficiently large.

On the one hand, the light source is pulsed in this concept. In addition, the detection unit, so the pixel array, switched pulsed sensitive. In other words, the integration window of the individual pixels is synchronized in time with the light source and limited in the integration period. By comparing results with different integration periods, in particular effects of background light can be excluded.

It is essential that this collection method is not a purely image-based acquisition method. It is determined at each pixel distance information, which is done by the temporal light detection. Finally, when using a pixel array, there is a matrix of distance values that allows for cyclic detection interpretation and tracking of object motion.

A sensor system of the type described input is for example from the DE 10 2013 108 824 A1 known. In this known sensor system, the sensor device is integrated together with the light source and the receiving or detecting device into a unit in a sensor housing, which is mountable on the motor vehicle. A disadvantage of this prior art is that the light beam emitted by the light source is aligned obliquely on the detection area and incident on this. As a result, the area in front of the vehicle, ie the detection area, is inhomogeneously illuminated by the light source, which can lead to problems with the detection of objects in the detection area.

The invention has for its object to provide a solution that provides a sensor system in a structurally simple manner and cost, which avoids the known from the prior art problem and provides a homogeneous illumination of the detection range of the 3D camera, so that the detection area a uniform light intensity experiences.

In a sensor system of the type described input, the object is achieved in that the light source has a transmitting optics for predetermined dispersion of the emitted light, wherein the transmitting optics, a first lens and a second lens, which is arranged in the direction of the emitted light behind the first lens , wherein at least one boundary surface of at least one of the two lenses is formed as a free-form surface.

Advantageous and expedient refinements and developments of the invention will become apparent from the dependent claims.

By the invention, a sensor system is provided, which is characterized by a functional design. Because at least one boundary surface of at least one of the two lenses is formed as a free-form surface, the illumination of the detection region can be predetermined by a suitable design of the free-form surface or free-form surfaces. For the present application of the optical detection of objects and their spatial movements, i. of movement gestures, a homogeneous illumination of the detection area is ensured by the measure of the at least one free-form surface, whereby a secure and high-resolution detection of objects in the detection range of the 3D camera is ensured, thus resulting in that overall high performance of the sensor device in terms of the detection reliability and detection sensitivity is obtained.

In order to improve the machinability of the transmitting optics, it is advantageous in an embodiment of the invention if at least one of the two lenses is quadrangular. A quadrangular lens can be used to edit the interfaces easier and more precise clamping than a disc-shaped lens.

The invention provides in a further embodiment that at least one of the two lenses is rectangular. By a rectangular design of the one lens or the two lenses, an exact positioning or arrangement of the corresponding lens in the transmitting optics is possible, so that an incorrect alignment of the lens or the lenses is no longer possible, because the long sides and the broad sides different are long.

In a further embodiment of the invention, it is provided that the first lens is formed with inwardly curved boundary surfaces. Accordingly, the first lens acts as an expansion optic in the sensor system and increases the cone generated by the emitted light.

For a targeted expansion of the light, it is advantageous in an embodiment of the invention if the inwardly curved boundary surfaces of the first lens are two-dimensional bulges which extend along a first spatial direction. Thus, the emitted light can be expanded in a first axis or spatial direction after a predetermined dispersion.

In order to diffuse the light through the first lens, it is further provided in an embodiment of the invention that the radius of curvature of the curvature of the boundary surface of the first lens facing away from the second lens is smaller than the radius of curvature of the curvature of the interface of the first lens facing the second lens.

In an advantageous embodiment of the second lens, the invention provides that the second lens has an inwardly curved boundary surface and an interface formed as a free-form surface. The designed as a free-form surface interface allows targeted illumination of the detection range of the 3D camera, so that the detection area can now be illuminated with a homogeneous light intensity.

For the targeted widening of the light beam in a desired axis or spatial direction, it is advantageous in the case of the second lens if the interface of the second lens facing the first lens is a two-dimensional curvature that extends transversely to the curvatures of the first lens. Accordingly, the first lens provides for expansion of the light in a first spatial direction, whereas the expanded light is expanded by the second lens in a second spatial direction, which is transverse to the first spatial direction. The light is thus widened by means of the two lenses in different axes.

In an embodiment of the invention is then further provided that the remote from the first lens interface of the second lens has the free-form surface, wherein the free-form surface is formed two-dimensionally. The two-dimensional formation causes the expansion in the desired spatial direction or axis.

With regard to a targeted distribution of the light intensity in the detection range of the 3D camera, the invention provides in a further embodiment, that the change in area of the free-form surface extends transversely to the curvatures of the first lens, wherein the area change from a homogeneous distribution of brightness to be achieved in the detection range of the 3D Camera derives.

For the field of application on a motor vehicle, the inventors have found that it is of particular advantage for a homogeneous illumination of the detection area if the second lens substantially has the shape of the number seven.

It is understood that the features mentioned above and those yet to be explained can be used not only in the particular combination given, but also in other combinations or in isolation, without departing from the scope of the present invention. The scope of the invention is defined only by the claims.

Further details, features and advantages of the subject matter of the invention will become apparent from the following description taken in conjunction with the drawing, in which an exemplary preferred embodiment of the invention is shown.

In the drawing shows:

1 a schematic arrangement of a sensor system according to the invention on a motor vehicle,

2 a perspective view of the sensor system according to the present invention,

3 a schematic representation of an inhomogeneous illumination of a detection area,

4 a light source of the sensor system according to the invention in perspective view,

5 an individual perspective view of the light source of the sensor system according to the invention,

6 a single part representation of a transmission optical system of the light source of the sensor system according to the invention,

7 a schematic representation of a beam path of the light source of the sensor system in a plan view,

8th in perspective plan view, the transmission optics of the light source of the sensor system according to the invention,

9 in a schematic representation of a beam path of the light source of the sensor system in a side view and

10 in perspective side view of the transmission optics of the light source of the sensor system according to the invention.

In 1 is the rear of a motor vehicle 1 to see. In this motor vehicle 1 is in the rear-side bumper, which is a motor vehicle component 2 of the motor vehicle 1 represents a sensor system according to the invention 3 arranged.

The sensor system 3 includes a sensor device 4 and a sensor device 4 accommodating sensor housing 5 , The sensor device 4 itself has a 3D camera that captures spatial data with a runtime method and that has a light source 6 and a light-sensitive receiving device 7 includes. The coverage area 8th the 3D camera of the sensor device 4 is down, to the sides and to the rear of the vehicle 1 directed away, the sensor system 3 intended to detect the operating gesture for the operation of a tailgate. The user can do this in the coverage area 8th perform a gesture with his foot, which is recognized as a control request and an electric opening of the tailgate of the motor vehicle 1 triggers. The control, evaluation and supply of the sensor device 4 via a uniform wiring harness, in particular a plug connection 9 on the sensor housing 5 is intended for coupling with a cable harness.

The entire coverage area 8th the 3D camera or the sensor device 4 extends over a large solid angle, like from the 1 and 2 shows, in 2 in a perspective view of the sensor housing 5 and the cone of the light source 6 emitted light is shown. In the 3 is a biaxial diagram to see in which the sensor device 4 and that of the light source 6 illuminated detection area 8th are shown schematically, wherein the dashed lines represent the outer and the light cone limiting light rays. The solid line in the diagram of 3 represents the light intensity 10 represents, with which the light source 6 the coverage area 9 illuminates. As from the diagram in 3 is recognizable, is the detection area 8th not lit with a homogeneous intensity. Rather, it behaves in such a way that with increasing distance 11 (x-axis of the diagram in 3 ) from the motor vehicle 1 the intensity 12 (y-axis of the diagram in 3 ) of the light decreases. The diagram in 3 shows a state, as it is known from the prior art. In contrast, with the present invention, such inhomogeneity (line 10 ) and a homogeneous illumination of the detection area 8th scored, as is the dashed line 14 in 3 shows, because here is the light intensity 10 ' over the detection area 8th constant. This homogeneous illumination of the detection area 8th based on the particular embodiment of the light source 6 the sensor system according to the invention 3 , which will be discussed below.

The light source 6 is in 4 in a perspective view and in 5 shown in a single part representation. The light source 6 includes a housing 15 and one the case 15 lid closing to one side 16 with a transparent window 17 through which light from the light source 6 is sent out. For adjustment purposes, the light source points 6 Further, an annular adjusting element 18 on which is on a mounting sleeve 19 seated. Inside the retaining sleeve 19 is then a light emitting unit 20 and a transmission optics 21 arranged one behind the other, as it is from the 5 and 6 evident.

Like that 5 and 6 can be seen, includes the transmission optics 21 , which serves for the predetermined dispersion of the emitted light, a first lens 22 and a second lens 23 in the direction of 24 the emitted light behind the first lens 22 is arranged. The two lenses 22 . 23 are square in the illustrated embodiment. In particular, the two lenses 22 . 23 rectangular, with the lenses 22 . 23 whose respective height is greater than the respective width. In the 7 and 9 is the beam path of the light emitting unit 20 emitted light through both lenses 22 . 23 shown, the 7 the beam path in a plan view and 9 show the beam path in a side view. In the 8th and 10 is the transmission optics 21 shown, where 8th one too 7 corresponding plan view and 10 one too 9 Corresponding side view of the transmission optics 21 demonstrate.

Like from the 6 to 10 it can be seen, is the first lens 22 with inwardly curved interfaces 25 and 26 educated. The first interface 25 the first lens 22 is with an inward curvature 27 provided, which is formed two-dimensionally, so that the curvature 27 as roundish and in a first spatial direction 28 extending recess on the otherwise flat surface of the interface 25 is trained. The other interface 26 the first lens 22 is also formed two-dimensional, with their inward curvature 29 also in the first spatial direction 28 extends (see for example 8th ). The radius of curvature of the curvature is 27 that of the second lens 23 remote interface 25 the first lens 22 smaller than the radius of curvature of the curvature 29 that of the second lens 23 facing interface 26 the first lens 22 , This two-dimensional configuration of the two interfaces 25 and 26 the first lens 22 leads to the in the 7 and 9 shown widening of the emitted light beam, such as the beam path 30 shows. Now to a homogeneous illumination of the detection area 8th To realize, the second lens has 23 an inwardly curved interface 31 and one as a freeform surface 32 trained interface 33 on. The inward curvature 34 (see for example 10 ), on the first lens 22 facing interface 31 the second lens 23 , extends in a second spatial direction 35 which are transverse or perpendicular to the first spatial direction 28 runs, so that also the interface 31 is formed two-dimensionally. Thus, the curvature extends 34 the interface 31 the second lens 23 across to the vaults 27 . 29 the first lens 22 , This inward curvature 34 the interface 31 causes a further symmetrical expansion of the light beam within the second lens 23 , The interface 33 with the freeform surface 32 on the other hand causes an asymmetrical widening of the light beam along the first spatial direction 28 such as the 9 can be seen. This is the point 36 a vehicle-related area of the coverage area 8th and the point 37 a vehicle-remote area of the coverage area 8th as seen from the synopsis of 1 . 3 and 9 is apparent. It should be noted that the detection area 8th in 7 the distribution of the light beams in the width direction of the vehicle 1 reproduces. How, in particular 9 shows is due to the special design of the interface 33 as a freeform surface 32 an intensity shift in the direction of the vehicle-distant area 37 achieved, which is indicated at the distance between the individual beams. According to the invention, the shaping of the free-form surface 32 the intensity of the vehicle-related area 36 shifted in the direction of the vehicle-distant area to a homogeneous illumination of the detection area 8th to achieve. For this reason, the area change of the free-form surface also extends accordingly 32 across to the vaults 27 . 29 the first lens 22 , As 10 shows, in the illustrated embodiment, the second lens 23 essentially the shape of the number seven, whereby deviating designs are conceivable as long as the shape of the second lens 23 and in particular the freeform surface 32 a homogeneous brightness distribution in the detection area 8th achieved the 3D camera.

In summary, it is the essence of the invention that the light source 6 a transmission optics 21 for the predetermined dispersion of the emitted light, wherein the transmitting optics 21 a first lens 22 and a second lens 23 in the direction of 24 the emitted light behind the first lens 22 is arranged, wherein at least one interface 33 of at least one of the two lenses 22 . 23 as a freeform surface 32 is trained. Here, the area change of the free-form surface is derived 32 from a homogeneous distribution of brightness to be achieved in the detection area 8th from the 3D camera. With the aid of the sensor system described above 3 and the transmission optics according to the invention 21 is an expansion of the light beam into different spatial axes 28 . 35 possible. Thereby, the light can be for every space axis 28 . 35 be individually expanded.

Of course, the invention described above is not limited to the described and illustrated embodiment. It will be appreciated that numerous modifications which are obvious to a person skilled in the art according to the intended application can be made to the embodiment shown in the drawing without departing from the scope of the invention. The invention includes everything that is contained in the description and / or shown in the drawing, including what is obvious to those skilled in the deviating from the specific embodiment.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been 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.

Cited patent literature

• DE 102008025669 A1 [0004]
• WO 2008/116699 A2 [0005]
• WO 2012/084222 A1 [0006]
• WO 2013/001084 A1 [0008]
• DE 102013108824 A1 [0017]

Cited non-patent literature

• "Photodetectors and Readout Concepts for 3D Time of Flight Image Sensors in 0.35 μm Standard CMOS Technology", Andreas Spickermann, Faculty of Engineering, University of Duisburg-Essen, 2010 [0010]
• Bernhard König, Faculty of Engineering, University of Duisburg-Essen, 2008 "Optimized Distance Measurement with 3D-CMOS Image Sensor and Real-Time Processing of 3D Data for Applications in Automotive and Safety Engineering" [0011]

Claims (11)

Sensor system ( 3 ) a sensor device ( 4 ) of a motor vehicle ( 1 ) for the optical detection of objects and their spatial movements, comprising a 3D camera, which records spatial data with a transit time method and which is a light source ( 6 ) and a light-sensitive receiving device ( 7 ), wherein the light source ( 6 ) and the light-intensive receiving device ( 7 ) in a common sensor housing ( 5 ) and both to a detection area ( 8th ) of the 3D camera, characterized in that the light source ( 6 ) a transmission optics ( 21 ) for predetermined dispersion of the emitted light, wherein the transmitting optics ( 21 ) a first lens ( 22 ) and a second lens ( 23 ) in the direction of the emitted light behind the first lens ( 22 ), wherein at least one interface ( 33 ) of at least one of the two lenses ( 22 . 23 ) as a freeform surface ( 32 ) is trained. Sensor system ( 3 ) according to claim 1, characterized in that at least one of the two lenses ( 22 . 23 ) is quadrangular. Sensor system ( 3 ) according to claim 1 or 2, characterized in that at least one of the two lenses ( 22 . 23 ) is rectangular. Sensor system ( 3 ) according to one of the preceding claims, characterized in that the first lens ( 22 ) with inwardly curved interfaces ( 25 . 26 ) is trained. Sensor system ( 3 ) according to claim 4, characterized in that the inwardly curved interfaces ( 25 . 26 ) of the first lens ( 22 ) two-dimensional curvatures ( 27 . 29 ), which extend along a first spatial direction ( 28 ). Sensor system ( 3 ) according to claim 5, characterized in that the radius of curvature of the curvature ( 27 ) of the second lens ( 23 ) remote interface ( 25 ) of the first lens ( 22 ) is smaller than the radius of curvature of the curvature ( 29 ) of the second lens ( 23 ) ( 26 ) of the first lens ( 22 ). Sensor system ( 3 ) according to one of the preceding claims, characterized in that the second lens ( 23 ) an inwardly curved interface ( 31 ) and one as a freeform surface ( 32 ) formed interface ( 33 ) having. Sensor system ( 3 ) according to one of the preceding claims, characterized in that that of the first lens ( 22 ) facing interface ( 31 ) a two-dimensional curvature ( 34 ), which transversely to the vaults ( 27 . 29 ) of the first lens ( 22 ). Sensor system ( 3 ) according to claim 8, characterized in that that of the first lens ( 22 ) remote interface ( 33 ) of the second lens ( 23 ) the freeform surface ( 32 ), wherein the freeform surface ( 32 ) is formed two-dimensionally. Sensor system ( 3 ) according to claim 9, characterized in that the area change of the freeform surface ( 32 ) across the vaults ( 27 . 29 ) of the first lens ( 22 ), wherein the change in area consists of a homogeneous distribution of brightness to be achieved in the detection area (FIG. 9 ) derives from the 3D camera. Sensor system ( 3 ) according to claim 9 or 10, characterized in that the second lens ( 23 ) has substantially the form of the number seven.

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