Vehicular electronic accessory module with enhanced grounding contact

A vehicular accessory module includes a circuit board and a metal enclosure. An electrically conductive grounding contact affixed at a first side of the circuit board and electrically connected to circuitry at the circuit board. The grounding contact is disposed between and contacts both the first side of the circuit board and the metal enclosure to provide an electrical connection between the circuit board and the metal enclosure. The grounding contact includes an abrasive surface that is in contact with the metal enclosure. Movement of the grounding contact relative to the metal enclosure causes the abrasive surface to scrape the metal enclosure to enhance grounding of the grounding contact with the metal enclosure.

FIELD OF THE INVENTION

BACKGROUND OF THE INVENTION

SUMMARY OF THE INVENTION

The present invention provides a driver assistance system or vision system or imaging system for a vehicle that utilizes one or more cameras (preferably one or more CMOS cameras) to capture image data representative of images exterior of the vehicle, and a circuit board and metal enclosure. The grounding contact is affixed at the circuit board and disposed between and contacts the circuit board and the metal enclosure to provide an electrical connection between the circuit board and the metal enclosure. The grounding contact includes an abrasive surface that is in contact with the metal enclosure. The accessory module may comprise a camera module having a camera that is operable to capture image data for a vehicular vision system or driving assist system of the vehicle.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A vehicular vision system and/or driver assist system and/or object detection system and/or alert system operates to capture images exterior of the vehicle and may process the captured image data to display images and to detect objects at or near the vehicle and in the predicted path of the vehicle, such as to assist a driver of the vehicle in maneuvering the vehicle in a rearward direction. The vision system includes an image processor or image processing system that is operable to receive image data from one or more cameras and provide an output to a display device for displaying images representative of the captured image data. Optionally, the vision system may provide display, such as a rearview display or a top down or bird's eye or surround view display or the like.

Referring now to the drawings and the illustrative embodiments depicted therein, a vehicle10includes an imaging system or vision system12that includes at least one exterior viewing imaging sensor or camera, such as a rearward viewing imaging sensor or camera14a(and the system may optionally include multiple exterior viewing imaging sensors or cameras, such as a forward viewing camera14bat the front (or at the windshield) of the vehicle, and a sideward/rearward viewing camera14c,14dat respective sides of the vehicle), which captures images exterior of the vehicle, with the camera having a lens for focusing images at or onto an imaging array or imaging plane or imager of the camera (FIG. 1). Optionally, a forward viewing camera may be disposed at the windshield of the vehicle and view through the windshield and forward of the vehicle, such as for a machine vision system (such as for traffic sign recognition, headlamp control, pedestrian detection, collision avoidance, lane marker detection and/or the like). The vision system12includes a control or electronic control unit (ECU)18having electronic circuitry and associated software, with the electronic circuitry including a data processor or image processor that is operable to process image data captured by the camera or cameras, whereby the ECU may detect or determine presence of objects or the like and/or the system provide displayed images at a display device16for viewing by the driver of the vehicle (although shown inFIG. 1as being part of or incorporated in or at an interior rearview mirror assembly20of the vehicle, the control and/or the display device may be disposed elsewhere at or in the vehicle). The data transfer or signal communication from the camera to the ECU may comprise any suitable data or communication link, such as a vehicle network bus or the like of the equipped vehicle.

Various aspects of the vision system (e.g., the control or processor, the camera(s), etc.) may be contained within an electronic module. The electronic module (such as a camera) may include a printed circuit board (PCB) disposed within a metal enclosure. Referring now toFIGS. 2A and 2B, it is common to use metal spring fingers to provide an electrical contact between the PCB and the metal enclosure. The electrical contact contains electrical noises within the electronic module and modules to comply with any Electromagnetic Compatibility (EMC) requirements. Pads of the spring fingers are soldered to the PCB and the spring fingers then make a compressive contact with the metal housing, thus electrically connecting the pad to the metal housing. The spring fingers may be used is to ensure an electrical contact through the lifetime of the module. However, the use of metal spring fingers may be relatively expensive and contribute to the overall cost of the module.

Implementations of the present invention provide a potentially cheaper alternative to spring fingers. Referring now toFIG. 3, one or more grounding contacts30are disposed on a circuit board32. The grounding contacts may, for example, be a foam-cored contact with a metalized polyimide film outer covering. The top of each grounding contact may include a pad34with a flat surface where it contacts the metal housing. Each grounding contact also includes an abrasive or roughened surface36or knurled surface or toothed surface to enhance engagement with and electrical connection with the metal housing or enclosure.

Many metal enclosures are cast aluminum, which quickly oxidizes to produce Aluminum Oxide (Al2O3), which is an electrical insulator. Because the grounding contacts or the structure in the camera that supports the circuit board may have different Coefficients of Thermal Expansion (CTE) than the aluminum enclosure, the metal enclosure and grounding contact will move relative to one another. With the roughened or abrasive contact surface of the grounding contact, such movement provides a wiping or scraping motion to rub or grind or scrape or otherwise remove the very thin layer of aluminum oxide that forms on the enclosure which helps allow the grounding contact30via the pad34to maintain good electrical contact with the metal enclosure. That is, the pad34that contacts the metal housing may be abrasive so that during thermal expansion, movement of the pad34relative to the housing or enclosure will remove buildup of aluminum oxide. The pad34may be formed with the abrasive or roughened or undulated surface (such as having sharp ridges or bumps or protrusions). For example, the pad may be corrugated. The pad may also be roughened using tools during or after manufacturing (e.g., drilling, grinding, sanding, etc.).

Therefore, the vision system provides for enhanced electrically conductive connection between circuitry at the printed circuit board and the metal enclosure or housing. The grounding contact has one side or surface affixed (such as via soldering or via a fastener or the like) to the circuit board (and in electrical connection with a ground circuit or conductive trace at the circuit board) and another side or surface (such as the opposite or distal side or surface distal from the attaching surface at the circuit board) that is roughened and that engages an inner surface of the metal housing or enclosure. The roughened surface provides enhanced electrical connection of the grounding contact with the metal enclosure and functions to remove buildup of aluminum oxide as the grounding contact may move relative to the enclosure during temperature fluctuations (due to different CTEs of the grounding contact material and the enclosure material).

Examples herein illustrate the grounding contact used in an accessory module having a printed circuit board (PCB) for a camera of an imaging system. The camera may comprise an exterior camera disposed at an exterior portion of the vehicle so as to view exterior of the vehicle, or the camera may comprise an interior mounted camera, such as a windshield-mounted camera that views forward through the windshield of the vehicle, or such as an interior cabin monitoring camera that is disposed in the cabin of the vehicle so as to view the driver and/or passenger(s) of the vehicle. The grounding contact may be disposed at an imager PCB of the camera module with the circuitry on the imager PCB including an imager, or the grounding contact may be disposed at a processor PCB of the camera module with the circuitry on the processor PCB including an image processor operable to process image data captured by the imager.

However, uses of the grounding contact are not limited to vision systems and may be used on any printed circuit board in any application. For example, the grounding contact may be incorporated at any type of vehicular accessory module, such as any other type of sensor of the vehicle (e.g., at a radar sensor or lidar sensor or microphone or the like), or at an ECU that is separate from the cameras or sensors. Optionally, the grounding contact may be used in any accessory module with a suitable metal enclosure and/or exposed to temperatures significant enough to generate scraping movements based on differences in CTEs of the housing and the grounding contact materials (e.g., exterior security cameras).

The camera may utilize materials that assist in accommodating changes in the camera when the camera is exposed to extreme temperatures, such as below −20 degrees C. or below −40 degrees C. and/or above 60 degrees C. or above 80 degrees C., and may utilize aspects of the cameras described in U.S. Publication Nos. U.S. Publication Nos. US-2020-0033549; US-2020-0154020; US-2020-0137926; US-2020-0001787; US-2019-0306966; US-2019-0121051; US-2019-0124243 and/or US-2019-0124238, and/or U.S. patent application Ser. No. 16/946,516, filed Jun. 25, 2020, which are all hereby incorporated herein by reference in their entireties.