WO2016112890A1

WO2016112890A1 - Camera of a driver assistance system and driver assistance system of a motor vehicle

Info

Publication number: WO2016112890A1
Application number: PCT/DE2015/200529
Authority: WO
Inventors: Franz Pfeiffer
Original assignee: Conti Temic Microelectronic Gmbh
Priority date: 2015-01-15
Filing date: 2015-12-08
Publication date: 2016-07-21
Also published as: DE102015200582A1; DE112015003570A5

Abstract

The invention relates to a camera (4) of a driver assistance system (2) of a motor vehicle, with an image sensor (10) as well as a printed circuit board assembly (38) comprising a circuit board (40), and comprising a camera housing (14). Said camera housing (14) comprises an outer wall (16) and a support (28) which is attached thereto, said support being at least partially surrounded by the outer wall (16) is arranged between the image sensor (10) and the circuit board (40). The invention additionally relates to a driver assistance system (2) of a motor vehicle.

Description

description

Camera of a driver assistance system and driver assistance system of a

motor vehicle

On the one hand, the invention relates to a camera of a driver assistance system of a motor vehicle, with an image sensor and, on the other hand, to a driver assistance system of a motor vehicle.

Motor vehicles include a variety of assistance systems, such. Rain sensors, lane departure warning or fatigue warning assistants. Each such assistance system has a camera, by means of which the windshield, the road or the driver is detected during operation. The detected image is checked for deviations from a certain desired state, and in the presence of an actuator actuated, such as a windscreen wiper motor, a motor for influencing the steering angle or an acoustic or optical signal generator.

Another field of application of such cameras is the provision of a close image of the surroundings of the motor vehicle. This is required, for example, when parking the motor vehicle in order to be able to recognize obstacles that are hidden due to the body design. A traffic flow in a side street can also be detected by means of such cameras, which remains (still) outside the field of vision of the driver of the motor vehicle, in particular with comparatively small junctions. Such cameras are usually integrated laterally in the front bumper, ie in the direction of travel at a front position of the motor vehicle. However, due to the requirements for pedestrian protection and also due to the provision of a deformation zone in the event of a collision, this area has only limited installation space, which is why the cameras can only have small dimensions. Also, there is usually no additional space available for an evaluation, so that it is usually integrated within the camera body of the camera. To reduce costs, the camera has only a circuit board on both the image sensor and the main processor of the control electronics are soldered. When the camera is operated, the main processor and thus also the adjacent image sensor are heated up, which leads to increased noise within the recorded images. As a result, the image quality is reduced, and the quality of the images taken by the camera does not match the quality for which the image sensor is designed.

The invention has for its object to provide a particularly suitable camera of a driver assistance system of a motor vehicle and a particularly suitable driver assistance system of a motor vehicle, with a camera, in particular increased image quality and preferably costs are reduced.

With regard to the camera, this object is achieved by the features of claim 1 and in terms of the driver assistance system by the features of claim 10 according to the invention. Advantageous developments and refinements are the subject of the respective subclaims.

The camera is part of a motor vehicle and in particular a driver assistance system, such as a parking aid, by means of which in particular a front area is detected by means of the camera. In particular, the camera is part of a surround view system. Conveniently, a lateral region of the motor vehicle is detected by means of the camera, so that a facilitated exit by means of the motor vehicle is made possible. In other words, the optical axis of the camera is perpendicular to the orientation of the motor vehicle, but at least an angle between them of between 1 10 ° and 70 ° is formed. Alternatively, the optical axis is parallel to the orientation of the motor vehicle, but at least an angle between them is less than 20 ° and in particular less than 10 °. In this case, the area in front of the motor vehicle is suitably detected with the camera.

The camera comprises an image sensor, which is for example a CCD or particularly preferably a CMOS chip. In other words, the image sensor works according to the CCD or CMOS principle. The camera further has a camera housing with an outer wall, which is designed, for example, in the manner of a hollow cylinder. In other words, the outer wall does not include a lid. Alternatively, the outer wall has a lid, and the outer wall is shaped like a container. Within the outer wall, a support of the camera body is arranged. In other words, the carrier is at least partially, preferably completely, surrounded by the outer wall. Consequently, the carrier is at least partially surrounded by the outer wall. Conveniently, the carrier is completely surrounded by the outer wall and protected by this. Thus, the carrier is disposed within the outer wall. The carrier is connected to the outer wall and formed, for example, on the outer wall. In other words, the camera body is preferably in one piece.

The carrier is for example part of a substantially U-shaped holder, with two mutually parallel legs, which are connected to each other at the free end by means of the carrier as this perpendicular leg. By means of the legs of the carrier is attached to the outer wall and suitably secured to the outer wall. Preferably, the holder is in one piece as well as e.g. designed in one piece with the outer wall, which simplifies the production. The carrier is expediently arranged perpendicular to an optical axis of the camera and preferably forms an intermediate plane of the camera housing within the outer wall, wherein the extent of the intermediate plane perpendicular to the optical axis is less than or equal to the plane bounded by the outer wall. In other words, at least one side, preferably circumferentially, a slot is formed between the carrier and the outer wall.

The camera further has a printed circuit board with a printed circuit board, to which in particular a number of electrical and / or electronic components are soldered. In the assembled state, the carrier, in particular mechanically, is arranged between the image sensor and the printed circuit board. For example, the carrier is surrounded in at least one dimension by means of the image sensor and the circuit board. Consequently, the image sensor is spaced from the circuit board and other components of the printed circuit board. By means of the carrier is a heat input of the PCB is reduced to the image sensor so that it can be operated with a relatively high resolution. Also, image noise of the measurement signals generated by the image sensor is reduced, so that the quality of images produced by the camera is increased.

Suitably, the image sensor is at least partially surrounded by the outer wall, preferably completely. In this way, the image sensor is protected by means of the outer wall against mechanical damage and environmental influences, or at least their influence is reduced. Conveniently, the image sensor is attached to the carrier. Preferably, both the carrier and the image sensor are arranged perpendicular to the optical axis. The image sensor is suitably attached directly to the carrier. In other words, the image sensor is in direct mechanical contact with the carrier. For example, the image sensor is glued to the carrier. In particular, a heat conducting foil or thermal paste is arranged between the image sensor and the carrier, which can dissipate heat dissipated due to the operation of the image sensor to the camera body.

Particularly preferably, however, a thermoelectric cooling element is arranged between the carrier and the image sensor. In other words, the image sensor is not in direct mechanical contact with the carrier. Suitably, the image sensor is in direct mechanical contact with the thermoelectric cooling element and the thermoelectric cooling element is preferably in direct mechanical contact with the support. Preferably, the image sensor is thermally conductively connected to the thermoelectric cooling element, for example by means of thermal paste. The thermoelectric cooling element is glued in particular to the image sensor. Preferably, the thermoelectric cooling element is a Peltier element, resulting in only slightly increased cost and a relatively low weight gain.

Regardless of the presence of the thermoelectric cooling element, so regardless of whether the image sensor is in direct or indirect mechanical contact with the carrier, takes place when mounting the image sensor to the carrier a Rollwinkeljustage. Because of the comparatively small error tolerance of the camera house, the adjustment is, for example, only a correct positioning of the camera body on a ground workbench. Due to the connection of the image sensor to the carrier thus eliminates a further step, namely a subsequent adjustment, resulting in a reduced production time and manufacturing costs, and in particular is required if the camera is located in front of the motor vehicle area.

Conveniently, the image sensor is a bare die. In other words, the image sensor has no housing. In other words, the image sensor is a nude chip. The image sensor is electrically contacted to the printed circuit board, for example, by means of a flexible printed circuit (FPC). In other words, by means of the flex circuit board, the measurement data acquired by means of the image sensor are directed to the printed circuit board. In an alternative to this, the image sensor is electrically contacted by bonding to the circuit board. In other words, the image sensor is bonded to the circuit board. For example, this is a thin wire with a diameter between 10 μιτι and 25 μιτι or a thick wire with a diameter between 100 μιτι and 500 μιτι used. In particular, first the image sensor and the printed circuit board are mounted within the outer wall and in a further step, the electrical connection between them created. In this way, the mounting of the image sensor and the circuit board is simplified, whereas the electrical coupling of the two requires only a small footprint. In particular, the tool required for this purpose is introduced through an opening of the camera housing, within which an optic of the camera is positioned in the assembled state.

Suitably, the circuit board abuts against the carrier, and preferably on the side of the carrier opposite the image sensor. In this way, only a comparatively short length of the electrical connection between the image sensor and the printed circuit board is required, which leads to comparatively low electromagnetic interference in the transmission of the measured values. For example, the printed circuit board comprises a control unit, by means of which the image sensor is controlled. In particular, measured data are evaluated by means of the control unit, which are recorded by means of the image sensor.

Suitably, the control unit is realized by means of a main processor, which is part of the printed circuit board. Conveniently, the main processor is soldered to the circuit board. For example, the main processor is a surface mount device ("SMD" device) which is preferably attached to the circuit board by a BGA process Alternatively, the main processor is bonded to the printed circuit board, more particularly, the carrier is located between the main processor and the image sensor or in combination therewith, the printed circuit board is positioned between the carrier and the main processor 12. Due to such an arrangement, heat input from the relatively hot main processor to the image sensor is reduced.

Suitably, the dimension of the circuit board is less than or equal to 40mm x 40mm. In particular, the dimension hereby designates the extent of the printed circuit board in a plane which corresponds to the main expansion plane of the printed circuit board, that is, which is parallel to the printed circuit board. Conveniently, this plane is perpendicular to the optical axis of the camera. For example, the printed circuit board is square or at least rectangular in shape. In particular, in this case an edge length of less than 35 mm, 30 mm, 25 mm or 20 mm. Conveniently, each of the edge lengths is greater than 15 mm, 20 mm, 25 mm, 30 mm, 35 mm. In this way, a comparatively compact printed circuit board is realized, so that the camera body can be manufactured with comparatively small dimensions, which facilitates installation within the motor vehicle.

For example, the circuit board has a recess, within which the carrier is at least partially positioned. If the carrier is part of a holder, for example, the carrier is preferably located completely inside the recess. The circuit board is expediently partially removed for creating the recess, for example milled. In particular, the recess is made in the manner of a blind hole. In other words, the output not completely through the PCB through. Consequently, the recess is a recess of the circuit board. In particular, the printed circuit board is attached to the carrier. For example, these are screwed together or glued together. In other words, a pocket geometry is created this way. Thus, a displacement of the circuit board with respect to the carrier is substantially prevented, so that the camera is relatively robust. If the image sensor is bonded to the circuit board, consequently, the electrical connections between the image sensor and the printed circuit board, even with shocks of the camera body are charged comparatively low, for example, in a poor travel.

In particular, a lens is attached to the camera body. For this purpose, the outer wall expediently has an opening in the manner of a hole, within which the lens is mounted. Alternatively, the lens is integral with the camera body, which prevents detachment. Conveniently, the camera body does not include a lens holder so that the number of parts needed to create the camera is reduced. The lens has, for example, a plastic or glass lens. In particular, the objective comprises a lens system with at least one glass lens and one plastic lens.

For example, the camera body is made of a metal. In this way, an influence of the printed circuit board due to electromagnetic fields is reduced. Appropriately, in this case, the camera body is contacted with ground, so that short circuits from the printed circuit board to the camera body are reduced due to the comparatively low electrical voltages. In addition, the camera body is relatively robust in this way. If the image sensor is connected to the carrier and thermally connected thereto, the image sensor thus essentially has the temperature of the camera body. In addition, if the main processor is present, a release of heat via the camera body to the environment is made possible, so that a substantially constant temperature prevails within the camera body. Conveniently, the metal used is aluminum or an aluminum alloy. In this way, the weight of the camera body is reduced, the processing is relatively easy. In an alternative to this, the camera body is made of a fiber-reinforced plastic, in particular glass fiber reinforced plastic. In this way, a comparatively lightweight and robust camera body is created. In addition, due to the thermally insulating properties of the fiber-reinforced plastic, such as epoxy resin, the image sensor from the main processor by means of the carrier thermally decoupled, if the main processor is present. In other words, the heat transfer between the main processor and the image sensor is further reduced. Preferably, the camera comprises a cover, by means of which the camera housing is closed after positioning both the image sensor and the printed circuit board. In this way, the image sensor and the printed circuit board is protected by the outer wall and the lid from environmental influences. Conveniently, the space within the camera body is dust and moisture protected and is created by means of the one hand, the outer wall, a possible bottom of the camera body, the lid and in particular the lens.

The driver assistance system of a motor vehicle has a camera with a camera housing, which comprises an outer wall and a carrier connected thereto. The carrier is at least partially surrounded by the outer wall, and in particular completely. The camera further comprises an image sensor and a printed circuit board with a printed circuit board. The carrier is arranged between the image sensor and the printed circuit board, in particular mechanically.

An embodiment of the invention will be explained in more detail with reference to a drawing. Show:

1 schematically simplified an assistance system with a camera,

2 in an exploded view of the camera from the front,

Fig. 3 in an exploded view of the camera from behind, and

Fig. 4-6 different mounting states of the camera. Corresponding parts are provided in all figures with the same reference numerals.

In Fig. 1, an assistance system 2 of a motor vehicle is shown schematically simplified. The assistance system 2 has a camera 4 and a signaling device 6 which are signal-technically coupled to one another. By means of the camera 4, the environment of the motor vehicle is received in the region of the front bumper. The images created in this way are made available to the driver by means of the signaling device 6 designed as a multifunction display. The camera 4 has an objective 8 with a plastic lens, by means of which an image sensor 10 is covered. The brightness values detected by means of the CMOS-based image sensor 10 are supplied to a control unit 12 and an image is reconstructed from the brightness values detected by means of the image sensor 10, ie from the recorded measurement data.

In Fig. 2 and 3, the camera 4 is shown in each case in an exploded view. The camera 4 comprises a camera housing 14 with an outer wall 16, which is designed in the manner of a cuboidal shell. In other words, the outer wall 16 includes a bottom 18 with a central circular opening 20. On the outer wall 16, a U-shaped holder 22 is formed in the region of the opening 20, which comprises two mutually parallel legs 24 which are parallel to an optical axis 26 extend the camera 4, and protrude into the area surrounded by the outer wall 16 area. The holder 22 comprises a carrier 28, by means of which the two legs 24 are connected, and which is aligned perpendicular to the optical axis 26. The remaining end of the two legs 24 is integrally formed on the bottom 18 of the outer wall 16. The support 28 is spaced from the outer wall 16 by the outer wall 16 in the radial direction with respect to the optical axis 26. The camera body 14 is made in one piece of aluminum or glass fiber reinforced plastic.

For mounting, the objective 8 is inserted into the opening 20 and held by means of the two limbs 24, the inner contour of which corresponds to the outer contour of the barrel-shaped objective 8. For attachment, the lens 8 either with the bolted to two legs 24, or glued or welded to the legs 24 or the bottom 18. The objective 8 has a first lens 30 and a second lens 32, by means of which the objective 8 is closed. Here, the first lens 30 faces away from the camera housing 14, whereas the second lens 32 is surrounded by the outer wall 16 in the assembled state. In other words, the second lens 32 is in a direction parallel to the optical axis 26 between the bottom 18 and the carrier 28. The first lens 30 is made of a plastic and the second lens 32 made of a glass. By means of the lenses 30, 32, the environment of the motor vehicle is projected onto the image sensor 10.

The image sensor 10 is a bare die based on CMOS technology. In other words, the image sensor 10 does not include a housing. The image sensor 10 is arranged perpendicular to the optical axis 28 and positioned in the assembled state between the lens 8 and the carrier 28. Here, a thermoelectric cooling element 34 in the form of a Peltier element is attached to the image sensor 10, on whose side facing the carrier 28, a thermoelectric cooling element. The remaining area of this side of the Peltier element is coated with thermal grease 36, by means of which the image sensor 10 is attached to the carrier 28. Here, the thermal compound 36 acts in the manner of an adhesive. In addition, the thermoelectric cooling element 34 is attached to the carrier 28 by means of a further adhesive. Consequently, the image sensor 10 is both mechanically and thermally coupled to the carrier 28, so that heat is emitted from the image sensor 10 to the camera body 14 and the carrier 28. Due to the integral nature of the camera body 14, this is in an aluminum manufacturing at the Outside wall 16 forwarded and discharged from there to the environment of the camera 4. If the camera housing 14 is made of glass fiber reinforced plastic, the thermal paste 36 is eliminated. Due to the comparatively poor heat conducting properties of the plastic, heat input from further components of the camera 4 to the image sensor 10 is essentially prevented, cooling of the image sensor 10 due to the thermoelectric cooling element 34 he follows.

The camera 4 further comprises a printed circuit board 38 with a printed circuit board 40 made of glass fibers reinforced epoxy resin. The printed circuit board 40 is perpendicular to the optimum see axis 26 aligned and square designed. The edge length is 40 mm. The printed circuit board 40 is positioned on the side of the holder 22 opposite the image sensor 10 and has a recess 42 in the form of a depression on the side facing the holder 22. The outer dimensions of the recess 42 correspond to the dimensions of the carrier 28 and the depth is substantially equal to half of the printed circuit board 40. In the assembled state, the carrier 28 is positively positioned in the recess 42 and is held there by means of an adhesive, causing a detachment of the printed circuit board 38th prevented by the camera body 14. In other words, the carrier 28 is disposed between the image sensor 10 and the circuit board 40.

On the side of the printed circuit board 40 opposite the carrier 28, the control unit 12 in the form of a main processor 44 as a surface-mounted component is soldered to the printed circuit board 40 in a BGA process. The main processor 44 has a self-contained housing and is mounted perpendicular to the optical axis 26 at the center of the circuit board 40. The square main processor 44 has an edge length of 30 mm and is mounted on the opposite side of the carrier 28 of the circuit board 40. During operation of the camera, the measured data generated by means of the image sensor 10 are evaluated by means of the main process 44 and a digital image is generated therefrom. The resulting heat loss is not transmitted to the image sensor 10 due to the one hand, the circuit board 40 and on the other hand due to the carrier 28, so that its measured values have a relatively low noise.

The camera 4 further comprises a cover, not shown, which is arranged parallel to the bottom 18 and perpendicular to the optical axis 26. This is connected to the bottom 18 opposite side of the outer wall 16 at this by means of screws. For this purpose, the camera housing 14 at two opposite corners on two parallel to the optical axis 26 extending screw receptacles 46.

4, a first mounting state of the camera 4 is shown. First, the one-piece motor housing 14 is created, for example, in die-cast aluminum method. In a further step, the image sensor 10 is positioned through the opening 20 within the outer wall 16 and fixed to the carrier 28. The image sensor 10, due to the design as bare die, has a number of bond wires 48 which project on both sides of the carrier 28. In a further step, as shown in Fig. 5, the printed circuit board 38 is inserted into the camera body 14 of the opening 20 opposite side of the outer wall 16, wherein the carrier 28 is positioned within the recess 42. The printed circuit board 40 is spaced from the outer wall 16 and the main processor 48 is located on the side of the printed circuit board 40 opposite the carrier 28 and the image sensor 10.

In a further step, as shown in Fig. 6, a bonding tool 50 is inserted through the opening 20 in the space formed by the outer wall 16 and the circuit board 40 and the bonding wires 48 of the image sensor 10 with non-illustrated interconnects Printed circuit board 40 electrically contacted. In other words, the image sensor 10 is bonded to the circuit board 40. As a result, the image sensor 10 is signal-wise connected to the main processor 44 by means of the bonding wires 48 and the printed conductors. In further steps, the lens 8 is positioned within the opening 20 and connected there. Also, the printed circuit board 38 is signal-wise connected to a line by means of which the camera 4 is coupled in the assembled state with the signal device 6. Further, the camera body 14 is closed with the lid.

The invention is not limited to the embodiment described above. Rather, other variants of the invention can be derived therefrom by the person skilled in the art without departing from the subject matter of the invention. In particular, all the individual features described in connection with the exemplary embodiment can also be combined with each other in other ways, without departing from the subject matter of the invention. List of reference numbers Assistance system

camera

signaling device

lens

image sensor

control unit

camera housing

outer wall

ground

opening

holder

leg

optical axis

carrier

first lens

second lens

thermoelectric cooling element

Wärmeleitplaste

PCB

circuit board

recess

main processor

screw receptacle

Bonding wire

The bonding tool

Claims

claims

Camera (4) of a driver assistance system (2) of a motor vehicle, both with an image sensor (10), and with a printed circuit board (40) having a printed circuit board (38), and with a camera housing (14) having an outer wall (16) and a carrier (28) connected thereto, which is at least partially surrounded by the outer wall (16) and which is arranged between the image sensor (10) and the printed circuit board (40).

Camera (4) according to claim 1,

characterized,

in that the image sensor (10) is connected to the carrier (28).

Camera (4) according to claim 2,

characterized,

a thermoelectric cooling element (34) is arranged between the image sensor (10) and the support (28).

Camera (4) according to claim 2 or 3,

characterized,

in that the image sensor (10) is a bare, which is in particular bonded to the printed circuit board (40).

Camera (4) according to one of claims 1 to 4,

characterized,

in that the printed circuit board (38) has a control unit (12), in particular a main processor (44).

Camera (4) according to one of claims 1 to 5,

characterized,

the dimension of the printed circuit board (40) is less than or equal to 40 mm × 40 mm, in particular less than or equal to 30 mm × 30 mm.

7. camera (4) according to any one of claims 1 to 6,

characterized,

in that the printed circuit board (40) has a recess (42) within which the carrier (28) is at least partially positioned.

8. camera (4) according to one of claims 1 to 7,

characterized,

in that a lens (8) is fastened to the camera housing (14).

9. camera (4) according to one of claims 1 to 8,

characterized,

the camera housing (14) is made of a metal, in particular an aluminum, or a fiber-reinforced plastic.

10. Driver assistance system (2) of a motor vehicle, with a camera (4) according to one of claims 1 to 9.