Supporting housing for stereo camera and circuit board

The present invention provides a stereo camera capable of mitigating thermal stress generated between members and reducing measurement error. In the present invention, a housing is provided with a high-rigidity support part and low-rigidity support part for supporting a circuit board, a high-rigidity support area including the high-rigidity support part, and a low-rigidity support area including the low-rigidity support part. The high-rigidity support part has greater rigidity in relation to force acting in a baseline direction (X-axis direction) following a baseline length of a pair of camera modules than the low-rigidity support part. The high-rigidity support area is provided in one location so as to be adjacent to the low-rigidity support area in the baseline direction.

TECHNICAL FIELD

The present invention relates to a stereo camera.

BACKGROUND ART

In the related art, an invention related to a camera system having a mounting system is known (see PTL 1 below). This conventional camera system comprises a circuit board and a frame.

The circuit board has a first end to which a first camera is electrically connected and a second end to which a second camera is electrically connected. In addition, the frame has a first frame member, a second frame member, and a mount for attachment to a vehicle.

In addition, the circuit board is arranged between the first frame member and the second frame member. 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 (see claim1of PTL 1).

The first frame member and the second frame member are made of, for example, materials having similar linear expansion coefficients. In the second frame member, for example, the side opposite to the circuit board or a surface thereof is fixed to the first frame member. Thus, since the movement of the front surface and the rear surface of the circuit board is balanced, the expansion of the second frame member positioned on the front surface side of the circuit board can reduce deflection or twist of the circuit board (see paragraph [0018] and the like in PTL 1).

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

In the case where the circuit board is arranged between the first frame member and the second frame member as in the conventional camera system, excessive force generated by a difference in the thermal expansion amount of the circuit board and the frame members may act on the connecting portions connecting the circuit board and the frame members. PTL 1 discloses a configuration that allows the circuit board to move relative to a support frame so as not to generate thermal stress (seeFIGS. 8 and 9, paragraph [0029] and the like in PTL 1).

More specifically, the circuit board has two horizontally extending slots and one vertically extending slot, and each of the slots allows a portion of the circuit board local to the slot to move relative to the frame within a range of the slot. This allows the stresses to be relieved when the camera system is exposed to extreme temperatures. Each of the slots accommodates a fixing member slidably connecting the circuit board and the frame.

However, the ease of relative movement between the circuit board and the frame varies depending on the fastening force by the fixing member and the frictional force between the members, and thus reproducibility is low and there are temporal changes. Therefore, when each of the members thermally expands, the measurement error of the stereo camera may disadvantageously increase with deformation occurring in each of the members that changes with time with low reproducibility.

The present invention has been made in view of the above problems, and it is an object of the present invention to provide a stereo camera capable of reducing the measurement error by alleviating thermal stress generated between members.

Solution to Problem

In order to achieve the above object, a stereo camera of the present invention includes: a pair of camera modules; a circuit board connected to the pair of camera modules; and a housing supporting the circuit board and the pair of camera modules, in which the housing includes: a high-rigidity support part and a low-rigidity support part for supporting the circuit board; a high-rigidity support area having the high-rigidity support part; and a low-rigidity support area having the low-rigidity support part, the high-rigidity support part has higher rigidity against force acting in a baseline direction along a baseline length of the pair of camera modules than that of the low-rigidity support part, and the high-rigidity support area is included at one location adjacent to the low-rigidity support area in the baseline direction.

Advantageous Effects of Invention

According to the stereo camera of the present invention, the circuit board is supported by the high-rigidity support part in the high-rigidity support area included at one location of the housing and is supported by the low-rigidity support part in the low-rigidity support area adjacent to the high-rigidity support area of the housing in the baseline direction along the baseline length of the pair of camera modules. Therefore, when thermal stress in the baseline direction acts between the circuit board and the housing due to a temperature change, the low-rigidity support part having lower rigidity than the high-rigidity support part is elastically deformed in the baseline direction to alleviate the thermal stress. This suppresses deformation of the housing supporting the pair of camera modules, thereby allowing the measurement error by the pair of camera modules to be reduced.

DESCRIPTION OF EMBODIMENTS

An embodiment of a stereo camera of the present invention will be described below with reference to the drawings.

First Embodiment

FIG. 1is a side view illustrating an installed state of a stereo camera1according to a first embodiment of the present invention. The stereo camera1of the present embodiment is a device which is installed in front of a windshield WS of a vehicle such as an automobile facing ahead in a traveling direction and captures images of roads, preceding vehicles, oncoming vehicles, pedestrians, obstacles, etc., and measures the distance to or the relative speed with respect to a subject, etc.

FIG. 2Ais a perspective view of a top surface side of the stereo camera1illustrated inFIG. 1.FIG. 2Bis a perspective view of a bottom surface side of the stereo camera1illustrated inFIG. 1.FIG. 3is an exploded perspective view of the stereo camera1illustrated inFIG. 2B. The stereo camera1of the present embodiment includes a pair of camera modules10, a circuit board20connected to the pair of camera modules10, and a housing30supporting the circuit board20and the pair of camera modules10.

FIG. 4is a perspective view of a camera module10illustrated inFIG. 3. The camera module10includes a cylindrical lens11and a sensor substrate12. The lens11is fixed to the sensor substrate12via a flange part13. The sensor substrate12has an image sensor (not illustrated), and the position thereof with respect to the lens11is adjusted such that an image having passed through the lens11is appropriately formed into the image at the center of the image sensor.

When the stereo camera1is installed as illustrated inFIG. 1, the camera module10is arranged close to the inclined windshield WS and can capture an image of an object present in the field of view VF ahead the vehicle. Note that, in each of the drawings, an orthogonal coordinate system is illustrated in which a direction connecting the pair of camera modules10, that is, a baseline direction along a baseline length BL which is the distance between the optical axes OA, is regarded as an X axis direction, the optical axis OA direction of the pair of camera modules10is regarded as a Z axis direction, and a direction perpendicular to the X axis direction and the Z axis direction is regarded as a Y axis direction.

The circuit board20is made of, for example, a glass epoxy base material, a ceramic base material, or the like. Although not illustrated, the circuit board20includes a signal processing circuit electrically connected to the sensor substrates12of the camera modules10by flexible wiring. On the rear side of the circuit board20, a connector21connected to the signal processing circuit is installed. The connector21of the circuit board20is connected to, for example, a connector of wiring connected to a vehicle control device (not illustrated). This allows the stereo camera1and the vehicle control device to be electrically connected.

The circuit board20has a substantially rectangular shape in which the X axis direction which is the baseline direction is the longitudinal direction and the Z axis direction which is the optical axis OA direction of the camera modules10is the lateral direction. The circuit board20has a plurality of through holes22through which fastening members such as screws23are inserted. The through holes22of the circuit board20are included at positions corresponding to screw holes included in board support parts32which will be described later.

The housing30has, for example, a main body31, the board support parts32, and a cover33. From the viewpoint of reducing the difference in deformation amount due to temperature changes and suppressing deformation, it is preferable that the material of the main body31and the material of the cover33have the same linear expansion coefficient or have as small a difference as possible in the linear expansion coefficient. The material of the housing30is not particularly limited, and a metal material such as an aluminum alloy may be used, for example.

The main body31has a substantially L-shape in a side view when viewed from the X axis direction and the height dimension gradually decreasing from the rear side to the front side of the vehicle in accordance with the inclination of the windshield WS.

More specifically, the main body31has a front end31F and a rear end31B in the direction of the optical axis OA of the camera modules10. The front end31F has a smaller height dimension in the height direction (Y axis direction) perpendicular to the baseline direction (X axis direction) and the optical axis OA direction (Z axis direction) than that of the rear end31B. Moreover, the front end31F has an inclined part31awhich is inclined with respect to the Z axis direction to face the windshield WS. As illustrated inFIG. 3, the main body31has a lower end and a rear end opened and has a space for accommodating the pair of camera modules10and the circuit board20.

The main body31has a camera support part31bhaving a substantially rectangular box shape with a large height at the rear end31B. The camera support part31bis capable of supporting the pair of camera modules10by, for example, allowing the lenses11of the pair of camera modules10to pass through a pair of circular openings31cincluded in a front wall part facing ahead of the vehicle and supporting the sensor substrates12of the camera modules10by side wall parts and an upper wall part. Alternatively, the camera support part31bmay support the flange parts13of the camera modules10with the front wall part. The main body31in capable of stably hold the pair of camera modules10the direction of the optical axis OA of which is precisely adjusted.

The main body31has cover fixing parts31dfor fixing the cover33. The cover fixing parts31dare, for example, each formed into a protruding shape having an end surface on which a screw hole is formed.

The main body31may have a pair of cover fixing parts31dscrew holes of which face downward (Y axis negative direction) at both ends in the baseline direction (X axis direction) inside the front end31F and a pair of cover fixing parts31dscrew holes of which face the rear side of the vehicle (Z axis negative direction) on the upper wall part of the camera support part31binside the rear end31B. The pair of cover fixing parts31dincluded on the upper wall part of the camera support part31bcan be arranged close to the camera modules10between the pair of camera modules10while spaced apart in the baseline direction.

The cover33has a bottom wall part33awhich closes the lower end of the main body31and a rear wall part33bwhich closes the rear end of the main body31and has an L-letter shape in a side view when viewed from the X axis direction, which is the baseline direction. The bottom wall part33ahas through holes33d, through which screws33cfor fixing the cover33are to be inserted, at positions corresponding to the screw holes of the cover fixing parts31dof the main body31at both ends of the front end in the X axis direction. The rear wall part33bhas through holes33d, through which screws33cfor fixing the cover33are to be inserted, at positions corresponding to the screw holes of the cover fixing parts31dof the main body31, the positions on an inner side with respect to both ends of an upper end in the X axis direction. In addition, the rear wall part33bhas an opening33ethat enables connection with another connector to the connector21at a position corresponding to the connector21of the circuit board20.

The board support parts32are integrally formed with the main body31and is provided as a part of the main body31, for example. A total of three board support parts32are provided while spaced apart from each other with one included inside the front end31F of the main body31of the housing30and the other two included on an inner side with respect to the camera support parts31bof the rear end31B of the main body31.

The board support part32provided on the front end31F of the main body31of the housing30is included in the central part of the main body31in the baseline direction (X axis direction). The two board support parts32provided at the rear end31B of the main body31of the housing30are arranged on the same linear line parallel to the X axis direction and are arranged at equal distances from the one board support part32provided at the front end31F of the main body31. Moreover, the board support parts32are arranged on an inner side between the pair of camera modules10in the baseline direction.

FIG. 5is a plan cross-sectional view illustrating the arrangement of the board support parts32illustrated inFIG. 3. In the stereo camera1of the present embodiment, the three board support parts32are arranged at apexes of an isosceles triangle.

Moreover, the perpendicular bisector of the base of the isosceles triangle defined by the three board support parts32is parallel to the Z axis direction which is the direction of the optical axis OA of the pair of camera modules10.

The rigidity of the board support parts32against the force in the baseline direction (X axis direction) along the baseline length BL of the pair of camera modules is lower than that of the main body31. Here, the rigidity of the board support parts32means how unlikely the force in the baseline direction to cause deformation thereof, and the rigidity of the main body31means how unlikely the force in the baseline direction which the main body31receives from the board support parts32to cause deformation thereof. A comparison between the rigidity of the board support parts32and the rigidity of the main body31can be performed, for example, as follows.

First, assuming that the board support parts32are rigid bodies and that the main body31is an elastic body. Then, calculate the deflection occurring in the main body31by the force in the baseline direction acting on the main body31generated by a difference in linear expansion coefficients of the circuit board20and the main body31. Next, assuming that the main body31is a rigid body and that the board support parts32are elastic bodies. Then, calculate the deflection occurring in the board support parts32by the force in the baseline direction acting on the board support parts32generated by a difference in linear expansion coefficients of the circuit board20and the main body31.

By comparing the deflection of the main body31and the deflection of the board support parts32calculated as described above, the rigidity of the main body31and the rigidity of the board support part32can be compared to each other. That is, in the case where the calculated deflection of the main body31is smaller than the deflection of the board support parts32, it can be understood that the rigidity of the main body31is higher than the rigidity of the board support parts32.

Note that the method for setting the rigidity of the board support parts32lower than the rigidity of the main body31is not limited to the method determined on the basis of the above comparison. For example, by making the board support parts32liable to elastic deformation as much as possible as long as sufficient durability against vibration and shock is achieved and improving the rigidity of the main body31as much as possible within a range allowed by restrictions of specifications, the rigidity of the board support parts32can be lower than the rigidity of the main body31.

The board support parts32may include a high-rigidity support part32H and low-rigidity support parts32L.

That is, the housing30is provided with the high-rigidity support part32H and the low-rigidity support parts32L for supporting the circuit board20, a high-rigidity support area30H having the high-rigidity support part32H, and low-rigidity support areas30L having the low-rigidity support parts32L. Note that, inFIG. 5, in order to facilitate distinguishing between the high-rigidity support part32H and the low-rigidity support parts32L, the high-rigidity support part32H is hatched. The high-rigidity support part32H has greater rigidity against force acting in the baseline direction (X axis direction) along the baseline length BL than that of the low-rigidity support parts32L.

In the example illustrated inFIG. 5, one board support part32provided on the front end31F of the housing30is the high-rigidity support part32H, and two board support parts32provided on the rear end31B of the housing30are the low-rigidity support parts32L. That is, in the stereo camera1of the present embodiment, the housing30has one high-rigidity support part32H and two low-rigidity support parts32L arranged to define an isosceles triangle having a base parallel to the baseline direction (X axis direction). The high-rigidity support part32H is arranged at the apex of the vertical angle of the isosceles triangle on the front side of the vehicle, and the low-rigidity support parts32L are arranged at the apexes of the base angles of the isosceles triangle on the rear side of the vehicle.

In the stereo camera1of the present embodiment, the high-rigidity support area30H of the housing30is included at one location adjacent to the low-rigidity support areas30L in the baseline direction (X axis direction). More specifically, the low-rigidity support areas30L are included at both ends in the baseline direction, and the high-rigidity support area30H is included between the low-rigidity support areas30L in the baseline direction. Moreover, the high-rigidity support area30H at the central part of the housing30has one high-rigidity support part32H, and the low-rigidity support areas30L at the both ends of the housing30each has one low-rigidity support part32L.

In the stereo camera1of the present embodiment, as illustrated inFIG. 3, the high-rigidity support part32H and the low-rigidity support part32L are provided as in a cylindrical shape in which the height direction (Y axis direction) is the axial direction. More specifically, the high-rigidity support part32H is provided at the front end31F of the main body31of the housing30, and the low-rigidity support parts32L are provided at the rear end31B of the main body31. Each of the high-rigidity support part32H and the low-rigidity support parts32L is formed in a columnar shape in which the height direction is the axial direction.

The axial height dimension of the high-rigidity support part32H is smaller than the axial height dimension of the low-rigidity support part32L. The diameters of the high-rigidity support part32H and the low-rigidity support part32L are substantially equal. In this manner, in a columnar board support part32extending in the axial direction and having substantially the same cross-sectional area, increasing the axial height dimension can reduce the rigidity in the baseline direction (X axis direction), and lowering the axial height dimension can improve the rigidity in the baseline direction.

Note that, in the case where the rigidity of the low-rigidity support parts32L is lower than the rigidity of the main body31against the force in the baseline direction (X axis direction), the rigidity of the high-rigidity support part32H may be higher than the rigidity of the main body31. That is, in the case of a plurality of board support parts32, it suffices that the rigidity of at least one board support part32is lower than the rigidity of the main body31against the force in the baseline direction. The screw holes for fastening screws for fixing the circuit board20are included on tip end surfaces of the high-rigidity support part32H and the low-rigidity support parts32L.

In the stereo camera1of the present embodiment, as illustrated inFIG. 3, the low-rigidity support parts32L and the high-rigidity support part32H are arranged on the inner side between the pair of camera modules10in the baseline direction (X axis direction).

The stereo camera1can be assembled, for example, by the following procedure. First, as illustrated inFIG. 3, the cylindrical lenses11of the pair of camera modules10are inserted from the inside of the pair of circular openings31cof the main body31of the housing30. Then, the optical axes OA of the pair of camera modules10are precisely adjusted, and the pair of camera modules10is fixed to the camera support part31bof the main body31. As a result, the pair of camera modules10is supported by the main body31of the housing30.

Next, the through holes22of the circuit board20are aligned with the screw holes of the high-rigidity support part32H and the low-rigidity support parts32L to allow the screws23inserted through the through holes22of the circuit board20to be fastened to the screw holes of the high-rigidity support part32H and the low-rigidity support parts32L. As a result, the circuit board20is supported by the board support parts32of the housing30, that is, the high-rigidity support part32H and the low-rigidity support parts32L.

Finally, the lower end and the rear end of the main body31are closed by the bottom wall part33aand the rear wall part33bof the cover33, and the through holes33dof the cover33are aligned with the screw holes of the cover fixing parts31dof the main body31to allow the screws33cinserted through the through holes33dof the cover33to be fastened to the screw holes of the cover fixing parts31d.

As a result, assembling of the stereo camera1including the pair of camera modules10, the circuit board connected to the pair of camera modules10, and the housing30supporting the circuit board20and the pair of camera modules10is completed. Thereafter, the stereo camera1can be installed in a vehicle for example via the windshield WS of a vehicle as illustrated inFIG. 1or via a bracket (not illustrated) fixed to a ceiling of a vehicle, etc.

Hereinafter, the operation of the stereo camera1of the present embodiment will be described.

As described above, the stereo camera1of the present embodiment includes the pair of camera modules10, the circuit board20connected to the pair of camera modules10, and the housing30supporting the circuit board and the pair of camera modules10. Therefore, it is enabled to capture an image of a measurement object such as a road ahead the vehicle, a preceding vehicle, an oncoming vehicle, a pedestrian, or an obstacle by the pair of camera modules10and to obtain the parallax of the measurement object from the images of the pair of camera modules10to obtain the distance to the measurement object.

For example, when the temperature of the stereo camera1changes due to sunshine or other reasons, force generated by a difference in the deformation amount due to the temperature change acts between the housing30and the circuit board20having different linear expansion coefficients. More specifically, for example, in the case where the material of the housing30is an aluminum alloy, the linear expansion coefficient of the housing30is about 23×10−6/° C. Meanwhile, in the case where the base material of the circuit board20is a glass epoxy base material, the linear expansion coefficient of the circuit board20is about 15×10−6/° C. In this case, when the temperature of the stereo camera1rises, the amount of thermal expansion of the housing30becomes larger than the amount of thermal expansion of the circuit board20.

Generally, as the baseline length BL, which is the distance between the optical axes OA of the pair of camera modules10, is longer, the measurement accuracy of the distance of the stereo camera1is improved. Therefore, the housing30of the stereo camera1has an elongated shape having a longitudinal direction in the baseline direction (X axis direction) along the baseline length BL, and in many cases the pair of camera modules10is installed to both ends in the baseline direction. In this case, for example, if the peripheral part of the circuit board20is firmly fixed to the housing30, the thermal expansion in the baseline direction of the housing30is restricted by the circuit board20having a small amount of thermal expansion, and such force that pulls the both ends of the housing30toward the central part in the baseline direction is applied thereto. When such force acts on the housing30, deformation such as deflection or warping occurs in the housing30, and the relative positional relationship between the pair of camera modules10changes to generate a parallax error, which may disadvantageously result in an increase in the measurement error of distance by the stereo camera1.

Here, in the stereo camera1of the present embodiment, the housing30has the main body31that supports the pair of camera modules10and the board support parts32that support the circuit board20. The low-rigidity support parts32L as the board support parts32have lower rigidity against the force in the baseline direction along the baseline length BL of the pair of camera modules10than that of the main body31. Therefore, the low-rigidity support parts32L supporting the circuit board20is elastically deformed more easily than the main body31to absorb the difference in the thermal expansion amount between the housing30and the circuit board20and to relieve the stress acting on the main body31, thereby enabling to suppress deflection or warping of the main body31.

More specifically, the housing30includes the high-rigidity support part32H and the low-rigidity support parts32L for supporting the circuit board20, the high-rigidity support area30H having the high-rigidity support part32H, and the low-rigidity support areas30L having the low-rigidity support parts32L. The high-rigidity support part32H has greater rigidity against force acting in the baseline direction along the baseline length BL of the pair of camera modules10than that of the low-rigidity support parts32L. The high-rigidity support area30H is included at one location so as to be adjacent to the low-rigidity support areas30L in the baseline direction.

As a result, it is enabled to firmly and stably support the circuit board20by the high-rigidity support part32H provided at the one high-rigidity support area30H adjacent to the low-rigidity support areas30L in the baseline direction (X axis direction). Furthermore, the low-rigidity support parts32L provided at the low-rigidity support areas30L adjacent to the high-rigidity support area30H in the baseline direction are allowed to be elastically deformed more easily than the high-rigidity support part32H.

That is, while the circuit board20is stably and firmly supported in the high-rigidity support area30H provided at one location of the housing30, it is enabled to absorb the difference in the thermal expansion amount between the housing30and the circuit board20by the elastic deformation of the low-rigidity support parts32L to suppress deflection or warping of the main body31. Therefore, according to the stereo camera1of the present embodiment, a relative displacement between the pair of camera modules10can be suppressed, an error in the parallax between the pair of camera modules10can be reduced, and a distance to a measurement object can be obtained more accurately.

On the other hand, in the case where the circuit board is arranged between the first frame member and the second frame member as in the conventional camera system, excessive force generated by a difference in the thermal expansion amounts of the circuit board and the frame members may act on the connecting portions connecting the circuit board and the frame members.

Also, in the conventional camera system, the circuit board has two horizontally extending slots and one vertically extending slot, and each of the slots allows a part of the circuit board local to the slot to move relative to the frame within a range of the slot. This allows the stresses to be relieved when the camera system is exposed to extreme temperatures. Each of the slots accommodates a fixing member slidably connecting the circuit board and the frame. However, the ease of relative movement between the circuit board and the frame in the conventional camera system varies depending on the fastening force by the fixing member and the frictional force between the members, and thus reproducibility is low and there are temporal changes. Therefore, when each of the members thermally expands, the measurement error of the stereo camera may disadvantageously increase with deformation occurring in each of the members that changes with time with low reproducibility.

More specifically, in the conventional camera system, when the sliding amount between the circuit board and the frame varies, the shape of the entire camera system after thermal deformation also varies, resulting in lower reproducibility of the parallax error. Moreover, in order to fix the circuit board and the frame while maintaining good sliding property such that there is no variation in the shape after thermal deformation of the entire camera system, it is extremely difficult to adjust the fastening force, and there is a concern that the fastening portion may be loosened due to vibrations. Furthermore, in the conventional camera system, in the case where the rigidity of the frame is increased to implement a robust structure so as to prevent deformation of the frame, the force acting on the fastening portion between the frame and the circuit board may increase, and sliding may occur even when the fastening force is increased, which may disadvantageously change the shape of the camera system after thermal deformation.

On the other hand, in the stereo camera1of the present embodiment, as described above, the thermal stress is alleviated by elastic deformation of the board support parts32having lower rigidity against the force in the baseline direction (X axis direction) along the baseline length BL of the pair of camera modules10than that of the main body31, that is, the low-rigidity support parts32L. Therefore, even when slight deformation occurs in the main body31due to the thermal stress after alleviation by the low-rigidity support parts32L, the deformation has good reproducibility.

Therefore, according to the stereo camera1of the present embodiment, the deformation of the main body31can be predicted with a good accuracy, and the parallax error can be corrected with high accuracy by image correction or the like between the pair of camera modules10. In addition, since no deformation occurs that changes over time, it is possible to eliminate the concern that the measurement error of the stereo camera1increases.

Furthermore, in the stereo camera1of the present embodiment, the low-rigidity support areas30L are included at both ends in the baseline direction (X axis direction), and the high-rigidity support area30H is included between the low-rigidity support areas30L in the baseline direction.

With this configuration, it is possible to reduce the distance between the high-rigidity support part32H and the low-rigidity support parts32L and to reduce the amount of elastic deformation of the low-rigidity support parts32L as compared with the case where the low-rigidity support area30L and the high-rigidity support area30H are included at one end and the other end in the baseline direction, respectively. Therefore, it is possible to alleviate the thermal stress by the low-rigidity support parts32L more easily. This further reduces the deformation of the main body31of the housing30, further reduces the parallax error between the pair of camera modules10, thereby enabling obtaining a distance to the measurement object more accurately.

In addition, with the above configuration, both sides of the middle part of the circuit board20supported by the high-rigidity support part32H are supported by the low-rigidity support parts32L. Therefore, in the circuit board20, the middle part in the baseline direction is stably and firmly held by the high-rigidity support part32H, and deformation from the middle part to the both ends in the baseline direction is accommodated by the elastic deformation of the low-rigidity support parts32L.

As a result, it is possible to support the middle part and the both ends of the circuit board20in a well-balanced manner to stabilize the deformation.

In particular, as illustrated inFIG. 5, by arranging one high-rigidity support part32H and two low-rigidity support parts32L at apexes of an isosceles triangle the base of which is parallel to the baseline direction, the middle part and the both ends in the baseline direction of the circuit board20can be supported in a more balanced manner at the three points, thereby further stabilizing the deformation.

As illustrated inFIG. 1, the windshield WS of a general vehicle is often inclined with respect to the vertical direction such that the lower side thereof is located on the front side of the vehicle than the upper side thereof. Therefore, by making the height dimension of the front end31F of the main body31smaller than the height dimension of the rear end31B, the stereo camera1can be arranged compactly in the vicinity of the windshield WS. In addition, since the main body31has a substantially L-shape in a side view, the housing30can be efficiently arranged in a limited space while the camera module10is brought close to the windshield WS.

Moreover, since the front end31F of the main body31of the housing30has the inclined part31ainclined like the windshield WS is, it is enabled to prevent interference between the housing30and the windshield WS and to secure the field of view VF of the camera module10with the camera module10brought close to the windshield WS.

Moreover, in the case where the height dimension of the front end31F of the main body31of the housing30is smaller than the height dimension of the rear end31B, as illustrated inFIG. 3, the board support part32provided on the front end31F of the main body31may be the high-rigidity support part32H and the board support parts32provided on the rear end31B of the main body31may be the low-rigidity support parts32L. That is, the high-rigidity support part32H is provided on the front end31F of the main body31, and the low-rigidity support parts32L are provided on the rear end31B of the main body31. The high-rigidity support part32H and the low-rigidity support parts32L are formed into a columnar shape in which the height direction is the axial direction.

This enables efficiently arranging the high-rigidity support part32H, which has a relatively small axial height dimension, in a space having a relatively small height dimension in the inner side of the front end31F of the main body31of the housing30. In addition, the high-rigidity support parts32H having a relatively large axial height dimension can be efficiently arranged in a space having a relatively large height dimension in the inner side of the rear end31B of the main body31. As a result, the stereo camera1can be downsized.

Furthermore, in the stereo camera1of the present embodiment, each high-rigidity support area30H has one high-rigidity support part32H. This prevents deformation of the circuit board20due to a temperature change from being disturbed by the high-rigidity support parts32H, thereby enabling more effectively suppressing deformation of the main body31. More specifically, in the case of providing two or more high-rigidity support parts32H, the effect of alleviating the thermal stress by allowing deformation of the circuit board20is reduced between the high-rigidity support parts32H. Therefore, by providing only one high-rigidity support part32H, it is possible to prevent the high-rigidity support part32H from disturbing deformation of the circuit board20due to a temperature change and to more effectively suppress deformation of the main body31.

In the stereo camera1of the present embodiment, all the board support parts32, that is, the low-rigidity support parts32L and the high-rigidity support part32H are arranged on the inner side between the pair of camera modules10in the baseline direction (X axis direction). This allows the baseline length BL of the pair of camera modules10to be longer, thereby improving the distance measurement accuracy of the stereo camera1.

As described above, according to the stereo camera1of the present embodiment, the thermal stress generated between the circuit board20and the housing30is relieved, thereby suppressing deformation of the main body31of the housing30supporting the camera module10and reducing the measurement error of the distance to a measurement object.

Note that in the stereo camera1of the present embodiment, the arrangement of the board support parts32is not limited to the above-described arrangement of an isosceles triangle. Moreover, the structure of the low-rigidity support parts32L is not limited to the columnar structure described above. Hereinafter, first to eighth variations of the arrangement of the board support parts32illustrated inFIG. 5will be described with reference toFIGS. 6A to 6H. A ninth variation of the low-rigidity support parts32L will be described with reference toFIG. 7.FIGS. 6A to 6Hare plan cross-sectional views illustrating the first to eighth variations corresponding to the arrangement of the board support parts32inFIG. 5.

A stereo camera1of the first variation illustrated inFIG. 6Ahas board support parts32at one end and the other end of a housing30in the baseline direction (X axis direction). More specifically, the housing30has one high-rigidity support area30H at one end in the baseline direction and one low-rigidity support area30L at the other end in the baseline direction. The high-rigidity support area30H has one high-rigidity support part32H, and the low-rigidity support area30L has one low-rigidity support part32L. The high-rigidity support part H and the low-rigidity support part32L may be arranged so as to support the central part of the circuit board20in the direction of the optical axis OA (Z axis direction) of the camera modules10, for example.

According to the arrangement of the low-rigidity support part32L and the high-rigidity support part H illustrated inFIG. 6A, the circuit board20can be stably and firmly supported by the high-rigidity support part32H at one end in the baseline direction of the housing30. Also, by elastically deforming the low-rigidity support part32L at the other end in the baseline direction of the housing30, deformation in the baseline direction of the circuit board20is allowed, and the force acting in the baseline direction of the main body31of the housing30can be relieved. Therefore, also in the stereo camera1of the first variation illustrated inFIG. 6A, similar effects to those of the stereo camera1described in the above embodiment can be obtained.

A stereo camera1of a second variation illustrated inFIG. 6Bhas one high-rigidity support area30H at one end in the baseline direction and one low-rigidity support area30L at the other end in the baseline direction like in the first variation. In the second variation, however, unlike the first variation the high-rigidity support area30H has two high-rigidity support parts32H, and the low-rigidity support area30L has two low-rigidity support parts32L.

Each of the two high-rigidity support parts32H and the two low-rigidity support parts32L may be arranged so as to support one end and the other end, respectively, of a circuit board20in the optical axis OA direction (Z axis direction) of camera modules10. Moreover, each of the two high-rigidity support parts32H and the two low-rigidity support parts32L may be arranged on a linear line parallel to the direction of the optical axis OA. That is, the high-rigidity support area30H has a plurality of high-rigidity support parts32H arranged while aligned in the direction of the optical axis OA intersecting the baseline direction (X axis direction).

According to the arrangement of the low-rigidity support parts32L and the high-rigidity support parts32H illustrated inFIG. 6B, it is possible to support four points of the circuit board20. Therefore, when vibration or shock acts on the stereo camera1, the circuit board20can be more firmly and stably supported, thereby enabling to further reduce vibration of the circuit board20. In this case, by arranging the two high-rigidity support parts32H on a linear line parallel to the direction of the optical axis OA in a direction intersecting the baseline direction (X axis direction), it is possible to prevent the two high-rigidity support parts32H from disturbing deformation of the circuit board20in the baseline direction.

This can effectively reduce the thermal stress acting in the baseline direction, which is greatly affected by the parallax error. Note that deformation of the circuit board20in the direction of the optical axis OA is disturbed by the two high-rigidity support parts32H, and thermal stress acting in the direction of the optical axis OA acts on the main body31. However, the thermal stress acting in the direction of the optical axis OA has less influence on the deformation of the main body31as compared with the thermal stress acting in the baseline direction, and influence on the parallax error is very small, and thus in most cases this does not pose a problem.

In a stereo camera1of a third variation illustrated inFIG. 6C, like in the embodiment described above, low-rigidity support areas30L are included at both ends in the baseline direction (X axis direction), and a high-rigidity support area30H is included between the low-rigidity support areas30L in the baseline direction. Further unlike the above-described embodiment, the stereo camera1of the third variation has a plurality of high-rigidity support parts32H in one high-rigidity support area30H and a plurality of low-rigidity support parts32L in one low-rigidity support area30L.

More specifically, the stereo camera1of the third variation has two high-rigidity support parts32H arranged on a linear line parallel to the direction of the optical axis OA (Z axis direction) in the central part of a housing30in the baseline direction. Moreover, the stereo camera1of the third variation has two low-rigidity support parts32L arranged on a linear line parallel to the direction of the optical axis OA (Z axis direction) in each of the both ends of the housing30in the baseline direction.

According to the stereo camera1of the third variation, effects similar to those of the above-described embodiment can be obtained. Furthermore, as compared with the stereo camera1of the above-described embodiment, by adding the high-rigidity support part32H and the low-rigidity support part32L that support the circuit board20, like in the second variation illustrated inFIG. 6B, the circuit board20can be more stably supported, thereby further ensuring prevention of vibration of the circuit board20.

In a stereo camera1of a fourth variation illustrated inFIG. 6D, like in the embodiment described above, low-rigidity support areas30L are included at both ends in the baseline direction (X axis direction), and a high-rigidity support area30H is included between the low-rigidity support areas30L in the baseline direction. Unlike the above-described embodiment, the stereo camera1of the fourth variation has a plurality of high-rigidity support parts32H in one high-rigidity support area30H like in the third variation illustrated inFIG. 6C.

According to the stereo camera1of the fourth variation, effects similar to those of the above-described embodiment can be obtained. Furthermore, as compared with the stereo camera1of the above-described embodiment, by adding the high-rigidity support part32H that supports the circuit board20, like in the third variation illustrated inFIG. 6C, the circuit board20can be more stably supported, thereby further ensuring prevention of vibration of the circuit board20.

Like the stereo camera1of the second variation illustrated inFIG. 6B, a stereo camera1of a fifth variation illustrated inFIG. 6Ehas one high-rigidity support area30H at one end in the baseline direction (X axis direction) and one low-rigidity support area30L at the other end in the baseline direction. However, in the fifth variation, unlike the second variation, the high-rigidity support area30H has a plurality of high-rigidity support parts32H arranged while aligned in the baseline direction, and the low-rigidity support area30L has a plurality of low-rigidity support parts32L arranged while aligned in the baseline direction.

In the stereo camera1of the fifth variation, deformation due to a temperature change of the circuit board20in the baseline direction tends to be hindered by the two high-rigidity support parts32H. However, if an interval between the two high-rigidity support parts32H in the baseline direction is less than or equal to a predetermined interval, for example, less than or equal to one-fifth of the dimension of the circuit board20in the baseline direction, deformation that affects the parallax error can be suppressed. Furthermore, by arranging the plurality of high-rigidity support parts32H and the plurality of low-rigidity support parts32L arranged in the baseline direction, the degree of freedom in designing the stereo camera1can be improved.

Like the stereo camera1of the fifth variation illustrated inFIG. 6E, a stereo camera1of a sixth variation illustrated inFIG. 6Fis different from the stereo camera1of the third variation illustrated inFIG. 6Cin that a high-rigidity support area30H has a plurality of high-rigidity support parts32H arranged in the baseline direction. Other points of the stereo camera1of the sixth variation are the same as those of the stereo camera1of the third variation illustrated inFIG. 6C. Also in the stereo camera1of the sixth variation, if an interval between the two high-rigidity support parts32H in the baseline direction is less than or equal to a predetermined interval, similar effects to those of the stereo camera1of the third variation illustrated inFIG. 6Ccan be obtained.

A stereo camera1of a seventh variation illustrated inFIG. 6Gis different from the stereo camera1of the above-described embodiment illustrated inFIG. 5in that a high-rigidity support area30H has a plurality of high-rigidity support parts32H arranged in the baseline direction. Other points of the stereo camera1of the seventh variation are the same as those of the stereo camera1of the above-described embodiment illustrated inFIG. 5. Also in the stereo camera1of the seventh variation, if an interval between the two high-rigidity support parts32H in the baseline direction is less than or equal to a predetermined interval, similar effects to those of the stereo camera1of the above-described embodiment illustrated inFIG. 5can be obtained.

A stereo camera1of an eighth variation illustrated inFIG. 6His different from the stereo camera1of the second variation illustrated inFIG. 6Bin that all the board support parts32of a housing30are low-rigidity support parts32L and that a high-rigidity support area30H nor a high-rigidity support part32H are included. According to the stereo camera1of the eighth variation, like the stereo camera1of the above-described embodiment, deformation of the circuit board20due to a temperature change is accommodated by the low-rigidity support parts32L, thereby alleviating the thermal stress acting on the main body31. Therefore, according to the stereo camera1of the eighth variation, similar effects to those of the stereo camera1described in the above-described embodiment can be obtained.

FIG. 7is a perspective view of a bottom surface side of a main body31of a housing30illustrating a variation of low-rigidity support parts32L. In the variation illustrated inFIG. 7, the housing30has not only low-rigidity support parts32L of a columnar shape provided on an inner side of a rear end31B of the main body31but also low-rigidity support parts32L of a cantilever shape provided on the front end31F of the main body31. That is, the low-rigidity support parts32L provided at the front end31F of the main body is each formed into a cantilever shape in a planar view when viewed from the height direction (Y axis direction).

Each of the low-rigidity support parts32L of a cantilever shape is provided, with a notch31eformed in an upper wall part of the front end31F of the main body31. The notch31eis formed, for example, along two sides in a longitudinal direction and a side in a lateral direction of a low-rigidity support part32L of a rectangular cantilever shape extending in one direction in a planar view when viewed from the height direction. That is, the notch31ehas a substantially U-shaped or channel-like shape surrounding in three directions around the low-rigidity support part32L of a rectangular cantilever shape extending in one direction in a planar view when viewed from the height direction.

The low-rigidity support parts32L of a cantilever shape may each have a columnar portion at the tip similarly to a high-rigidity support part32H and a screw hole included at the tip end surface of the columnar portion. When force acts in the baseline direction on the low-rigidity support parts32L of a cantilever shape, like a low-rigidity support part32L of a columnar shape, the low-rigidity support parts32L of a cantilever shape are elastically deformed more easily than the main body31to alleviate the stress acting on the main body31. The low-rigidity support parts32L of a cantilever shape have an advantage that the dimension in the height direction can be reduced as compared with a low-rigidity support part32L of a columnar shape.

Therefore, the low-rigidity support parts32L of a cantilever shape can be formed also on the front end31F of the main body31having a relatively small height dimension. Note that the low-rigidity support parts32L are not limited to a columnar shape or a cantilever shape. For example, instead of the notch31e, a part of the main body31may be formed into a low-rigidity support part32L by forming a thin part in that part of the main body31.

Although embodiments of the present invention have been described in detail with reference to the drawings, specific configurations are not limited to these embodiments, and design changes or the like within the scope not departing from the principles of the present invention are included in the present invention. For example, although the examples of the stereo camera arranged close to the windshield in a compact manner has been illustrated in the above-described embodiment and variations thereof, a configuration of a stereo camera of the present invention is not limited to the above examples.

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