Patent Application
20120081550
The present application relates generally to the field of camera systems. More specifically, the application relates to camera systems having improved mounting systems.
Circuit boards for stereo vision cameras are typically mounted on a single metal frame. The single metal frame creates the potential for differential expansion between the frame (or housing) and the board as temperature changes. The differential expansion causes the assembly to warp, which may cause misalignment between two cameras mounted on the circuit board.
Some sensor designs use multiple board assemblies with the cameras mounted on separate boards to control relative movement from thermal expansion. By mounting each camera on a separate board and using a heavy main frame the problem of differential thermal expansion and of thermal misalignment of the cameras may be minimized. However, such a multiple board assembly has a high cost, complexity, and potential misalignment should the fasteners holding the two separate camera boards in place loosen. It may also be difficult to reduce the size of the camera module when using multiple board assemblies.
What is needed is a system that allows use of a single circuit board system while reducing or eliminating camera misalignment caused by differential thermal expansion.
One embodiment disclosed relates to a camera system for use in a vehicle. The camera system includes a circuit board having a first end with a first camera electrically connected thereto and a second end with a second camera electrically connected thereto. The camera system also includes a frame having a first frame member, a second frame member, and a mount for attaching the camera system to the vehicle. The circuit board is disposed between the first and second frame members, and the first frame member is coupled to the second frame member at a first connection location proximate the first end and at a second connection location proximate the second end to reduce the deflection of the first and second ends of the circuit board relative to the mount to maintain the alignment of the first and second cameras.
Another embodiment disclosed relates to a mounting system for mounting a circuit board of a camera system, the circuit board having a portion configured to have at least one camera electrically connected thereto. The mounting system includes a first frame member, a second frame member, and a mount for attaching the mounting system to the vehicle. The first frame member is coupled to the second frame member through at least one connection location, such that the circuit board is disposed between the first and second frame members, and the at least one connection location is proximate to the at least one camera to reduce the deflection of the portion of the circuit board relative to the mount.
These and other features, aspects, and advantages of the present invention will become apparent from the following description and the accompanying exemplary embodiments shown in the drawings, which are briefly described below.
Before turning to the figures, which illustrate the exemplary embodiments in detail, it should be understood that the application is not limited to the details or methodology set forth in the description or illustrated in the figures. It should also be understood that the terminology is for the purpose of description only and should not be regarded as limiting.
Referring generally to the figures, a single circuit board design may be implemented that is configured to reduce warping of the circuit board by thermal expansion. In one exemplary embodiment, the circuit board may be mounted rigidly on a frame to constrain regions where the imagers or cameras are located. In another exemplary embodiment, a second frame member may be mounted on the opposite side of the circuit board from a first frame member to generate a counteracting force to reduce or prevent the warping motion or deflection of the circuit board. In another exemplary embodiment, the circuit board may be mounted on a frame in a manner that allows the board to slide independent of the expansion of the frame material. Such a sliding configuration may reduce or prevent warping of the board by not permitting force generation. In another exemplary embodiment, the expansion coefficient (e.g., coefficient of thermal expansion) of the circuit board may be determined and the frame and/or housing may be made from a material that has the same or similar expansion coefficient as the material comprising the board. Such a material selection may act to reduce or minimize the forces on the board and thus reduce or minimize warping.
As shown in
As shown, the camera system 110 includes two cameras 115, a circuit board 120, and a mounting frame 130 having a first frame member 131 (e.g., mounting frame member) and a second frame member 132 (e.g., stabilizing frame member). The two cameras 115 are mounted on a single circuit board 120 and may be aligned for optimal image sensing performance. The circuit board 120 has an elongated shape having a first end 121 with a first camera 115 electrically connected thereto and a second end 122 with a second camera 115 electrically connected thereto. The circuit board 120 is interposed the first and second frame members 131, 132, and the circuit board 120 may be mounted on or coupled to the first frame member 131 and/or second frame member 132. The first frame member 131 may be coupled to the second frame member 132 through connection locations 136. Each connection location 136 may include a fastener (e.g., screw, bolt, etc.) that couples the first frame member 131 to the second frame member 132 thereby clamping a connecting portion of the circuit board 120 between the first and second frame members 131, 132. Each frame member 131, 132 may include a connecting feature for each connection location 136, such as a shoulder having a hole, where the shoulder supports an abutting portion of the circuit board 120, and where the hole may receive a fastener or other suitable connecting element.
The camera system 110 is configured to mount to a vehicle or stationary location via a mounting point. For example, a mount 133 may connect the camera system 110 to a vehicle or other object, where the mount 133 may be integrally formed with the first frame member 131 or may be formed separately and coupled to the first frame member 131 using any suitable connecting method (e.g., welding, fasteners, etc.). The mount 133 may include an opening 134 (e.g., a mounting point, a mounting location) to receive a fastener to couple the camera system 110 to the vehicle, or may utilize any suitable method for coupling the camera system 110 to the vehicle. Alternatively, the mount 133 may include a plurality of mounting locations 134.
The first frame member 131 may have an elongated rectangular shape or any suitable shape, which may be generally solid, or may comprise a plurality of external walls with one or more support members (e.g., trusses, ribs) extending between the walls to provide structural support. The ends of the first frame member 131 may be configured to be coupled to the ends of the second frame member 132 and/or the circuit board 120, such as through connections.
The second frame member 132 may also have an elongated rectangular shape or any suitable shape, which may be generally solid, or may comprise a plurality of external walls with one or more support members (e.g., trusses, ribs) extending between the walls to provide structural support. The ends of the second frame member 132 may be configured to be coupled to the ends of the first frame member 131 and/or the circuit board 120, such as through connections. The ends of the second frame member 132 may also include an aperture configured to receive the camera (e.g., the lens of the camera).
The second frame member 132 (e.g., stabilizing frame member) may be made from the same material or from a material having a similar coefficient of thermal expansion as the first frame member 131 (e.g., mounting frame member), in order for the second frame member 132 to expand at the same (or similar) rate as the first frame member 131. The second frame member 132 may be secured to an opposing side or face of the circuit board 120 relative to the first frame member 131. Accordingly, the expansion of the second frame member 132 at the front of the circuit board 120 may reduce warping or twisting of the circuit board 120 because the movement of the front and back of the circuit board 120 is balanced.
The second frame member 132 may be capable of providing adequate force to balance the resultant force of expansion of the first frame member 131 and/or the circuit board 120. The balance may be achieved by making the frames identical, but the use of identical frames on both sides of the board may add weight and size to the camera system 10. For example, the second frame member 132 may have a curved beam geometry to limit the amount of material used to provide the balancing force. The resulting camera system 110 may have very little misalignment of the cameras 115 over a wide range of operating temperatures (e.g., between about −40 C and about 85 C) and be relatively small and have a low weight.
The effect of warping may be most severe with respect to measuring the distance from the mounting location to an object. The use of the two-member frame 130 maintains high performance and accurate measurement over the entire operational temperature range of the camera system 110. Weight of the camera system 110 may be kept to a minimum to improve durability of the system to a vehicle windshield or other location.
In some exemplary embodiments, such as, for example, the two-member frame 130, the first and second frame members 131, 132 of the camera system 110 may be made of a material with thermal expansion properties similar to those of the circuit board 120. For example, one or both of the first and second frame members 131, 132 may be made of bulk-molding compound (BMC), aluminum silicon carbide, or another material having thermal properties similar to that of the circuit board 120. Such a configuration may enhance the effectiveness of the stabilizing frame 130 and may reduce the stress on the circuit board 120 caused by thermal expansion. In certain embodiments, the second frame member 132 may also be omitted to further reduce the size and weight of the camera system, such as with camera system 10 while providing a reduction in warping and twisting, such as by having the mounting frame 30 made from a material having similar thermal expansion properties as the circuit board 20.
Now turning to
As shown in
As shown in
The cover 240 and housing 250 may be made of plastic or any other suitable material, such as another light (e.g., weight) material. The light weight cover 240 and housing 250 may be configured so that the cover 240 and housing 250 do not interfere with thermal movement or expansion of the frame (e.g., the first and second frame members 231, 232) and/or circuit board 220. Either alone or in combination, the cover 240 and housing 250 may protect the circuit board 220, cameras, or other components of the system.
As shown in
The preceding exemplary embodiments disclose that the board may be firmly clamped, such as to the frame or to the housing and/or cover. For example, the board may be firmly clamped to the frame at each connection (e.g., attachment point) so that the board is firmly fixed to the frame (e.g., a frame member) and therefore moves with the frame at the connection, in the event of any such movement. Such fixed connections or attachment configurations control the warp at the camera positions (e.g., camera mounts) and may be less complicated to construct, however, may also, under some circumstances, impose thermal stress on the printed circuit board.
The camera system 310 having sliding connections between the circuit board 320 and the frame 330 may reduce warp and reduce thermal stress on the circuit board 320. Both the normal force and the frictional force are controlled at the circuit board mounting positions or locations. Frictional force may be minimized to allow movement in the plane in which the circuit board 320 is configured in. The circuit board 320 may be any suitable board having a high degree of flatness. The circuit board 320 is fixed against horizontal movement at the vertical movement slot but is allowed to move vertically. The board is fixed against vertical movement at the one or more horizontal movement slots 327, but is allowed horizontal movement. While a specific number of vertical and horizontal movement slots 327, 328 are shown in the circuit board 320, in other exemplary embodiments, any number of vertical and horizontal movement slots 327, 328 may be used in the board. The vertical and horizontal movement slots 327, 328 may be positioned at various locations on the circuit board 320, which may vary from the locations shown in
Although the camera systems are illustrated as including multiple features utilized in conjunction with one another, each system may alternatively utilize more or less than all of the noted mechanisms or features shown in any of the camera systems shown or described herein. For example, in other exemplary embodiments, more or fewer connections (e.g., mounting locations) may be used in the system.
Although specific shapes of each element have been set forth in the drawings, each element may be of any other shape that facilitates the function to be performed by that element. For example, the cameras have been shown to be round or cylindrical, however, in other exemplary embodiments the structure may define cameras or imaging chips of other shapes.
For purposes of this application, the term “coupled” means the joining of two components (electrical, mechanical, or magnetic) directly or indirectly to one another. Such joining may be stationary in nature or movable in nature. Such joining may be achieved with the two components (electrical or mechanical) and any additional intermediate members being integrally defined as a single unitary body with one another or with the two components or the two components and any additional member being attached to one another. Such joining may be permanent in nature or alternatively may be removable or releasable in nature
The present application has been described with reference to example embodiments, however persons skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the claimed subject matter. For example, although different example embodiments may have been described as including one or more features providing one or more benefits, it is contemplated that the described features may be interchanged with one another or alternatively be combined with one another in the described example embodiments or in other alternative embodiments. Because the technology of the present disclosure is relatively complex, not all changes in the technology are foreseeable. The present disclosure described with reference to the example embodiments and set forth in the following claims is manifestly intended to be as broad as possible. For example, unless specifically otherwise noted, the claims reciting a single particular element also encompass a plurality of such particular elements.
It is also important to note that the construction and arrangement of the elements of the system as shown in the preferred and other exemplary embodiments is illustrative only. Although only a certain number of embodiments have been described in detail in this disclosure, those skilled in the art who review this disclosure will readily appreciate that many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter recited. For example, elements shown as integrally formed may be constructed of multiple parts or elements shown as multiple parts may be integrally formed, the operation of the assemblies may be reversed or otherwise varied, the length or width of the structures and/or members or connectors or other elements of the system may be varied, the nature or number of adjustment or attachment positions provided between the elements may be varied. It should be noted that the elements and/or assemblies of the system may be constructed from any of a wide variety of materials that provide sufficient strength or durability. Accordingly, all such modifications are intended to be included within the scope of the present disclosure. Other substitutions, modifications, changes and omissions may be made in the design, operating conditions and arrangement of the preferred and other exemplary embodiments without departing from the spirit of the present subject matter.
The present application claims the benefit of and priority to U.S. Provisional Patent Application No. 61/389,553 filed on Oct. 4, 2010. The foregoing provisional application is incorporated by reference herein in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61389553 | Oct 2010 | US |
