JP2014204383A - On-vehicle stereo camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the occurrence of a deviation in the optical axis of an image pickup unit attached at either end in longitudinal direction of a stay.SOLUTION: An on-vehicle stereo camera comprises: a first image pickup body to which a first image pickup unit for capturing a subject image is attached; a second image pickup body to which a second image pickup unit for capturing a subject image is attached; a circuit board on which a circuit for processing a signal outputted from the first and second image pickup units is provided; and a stay extending in the longitudinal direction. The first image pickup body is fixed at one end in longitudinal direction of the stay, and the second image pickup body is fixed at the other end in longitudinal direction of the stay. The circuit board is composed of a plurality of partial circuit boards divided along the longitudinal direction of the stay, each of the partial circuit boards having a first hole used for fixation having freedom for the stay in the longitudinal direction and a second hole used for fixation without freedom for the stay in the longitudinal direction.

Description

  The present invention relates to an in-vehicle stereo camera.

  Conventionally, a stereo camera in which a pair of camera modules is attached to both ends of a camera stay in the longitudinal direction is known (for example, Patent Document 1).

JP 2010-41373 A

  However, when the bracket is warped, there is a problem in that the optical axis of the pair of camera modules is displaced, and the accuracy of the distance to the preceding vehicle calculated based on the principle of triangulation is lowered.

  The in-vehicle stereo camera according to claim 1 captures a subject image via a first imaging housing to which a first imaging unit that captures a subject image via a first optical member is attached, and a second optical member. A second imaging housing to which the second imaging unit is attached; a substrate on which a circuit for processing signals output from the first imaging unit and the second imaging unit is provided; and a stay extending in the longitudinal direction; The first imaging housing is fixed to one end in the longitudinal direction of the stay, the second imaging housing is fixed to the other end in the longitudinal direction of the stay, and the substrate is Each of the partial substrates is configured with a first hole for fixing with a degree of freedom in the longitudinal direction with respect to the stay and a longitudinal direction with respect to the stay. And a second hole for fixing without having a degree of freedom. To.

  According to the present invention, each of the partial substrates divided into a plurality along the longitudinal direction of the stay is fixed to the stay with a degree of freedom in the longitudinal direction via the first hole, and the second hole. Since it can fix to a stay without having a freedom degree to a longitudinal direction via this, it can suppress that the shift | offset | difference of an optical axis arises in a 1st and 2nd imaging part.

It is a disassembled perspective view explaining the internal structure of the stereo camera apparatus by one embodiment of this invention. It is a perspective view explaining the inside of a stay which constitutes a stereo camera device by one embodiment. It is a perspective view explaining the inside of a cover which constitutes a stereo camera device by one embodiment. It is a perspective view explaining the board | substrate attached to the stay of the stereo camera apparatus by one Embodiment.

  An embodiment of a stereo camera device according to the present invention will be described with reference to the drawings. In this specification, a stereo camera device that is an external recognition sensor that is provided in a vehicle such as a passenger car and is used as one of in-vehicle safety devices will be described as an example. The stereo camera device uses a triangulation principle and uses the respective images acquired by two imaging units provided apart from each other at intervals of a base line length (for example, about 200 mm to 400 mm) to reach an object. Measure the distance.

  FIG. 1 is an exploded perspective view illustrating the internal structure of a stereo camera device according to an embodiment. In the following description, it is assumed that a coordinate system including the x-axis, y-axis, and z-axis is set as shown in the figure. As shown in FIG. 1, the stereo camera device 100 includes a stay 7, a cover 13, a first imaging unit 110, and a second imaging unit 120. The stay 7 is made of a metal material such as aluminum and extends with the x-axis direction as a longitudinal direction. The cover 13 is made of a metal material such as aluminum and extends with the x-axis direction as a longitudinal direction.

  The first imaging unit 110 includes a first imaging element 111, a first imaging substrate 112, a first lens 113, a first imaging housing 114, and a first cover 115. The first lens 113 is attached to the first imaging housing 114 so that the y-axis and the optical axis are parallel to each other, and passes the light beam from the subject existing on the y-axis + side and guides it to the first imaging element 111. . The first imaging element 111 is configured by a CCD, a CMOS, or the like, and is attached to the first imaging casing 114 so as to be orthogonal to the optical axis of the first lens 113. The first image sensor 111 receives a light beam from a subject (a front vehicle, a person, etc.) via the first lens 113, and outputs the subject image as a photoelectric conversion signal. The first imaging substrate 112 is attached to the first imaging housing 114, and operates the first imaging element 111 by receiving power from a power supply circuit described later. The first imaging housing 114 is attached to the end of the stay 7 on the x axis + side so that the light receiving surface of the first imaging element 111 is parallel to the xz plane. The first cover 115 is a protective member that covers the first imaging substrate 112 from the z axis + side.

  The second imaging unit 120 includes a second imaging element 121, a second imaging substrate 122, a second lens 123, a second imaging housing 124, and a second cover 125. The second lens 123 is attached to the second imaging housing 124 so that the y-axis and the optical axis are parallel to each other, and passes the light beam from the subject existing on the y-axis + side and guides it to the second imaging element 121. . The second imaging element 121 is configured by a CCD, a CMOS, or the like, and is attached to the second imaging casing 124 so as to be orthogonal to the optical axis of the second lens 123. The second image sensor 121 receives a light beam from a subject (a front vehicle, a person, etc.) via the second lens 123, and outputs the subject image as a photoelectric conversion signal. The second imaging substrate 122 is attached to the second imaging housing 124, and operates the second imaging element 121 upon receiving power from a power supply circuit described later. The second imaging housing 124 is attached to the end of the stay 7 on the x-axis side so that the light receiving surface of the second imaging element 121 is parallel to the xz plane. In other words, the light receiving surface of the first image sensor 111 and the light receiving surface of the second image sensor 121 are attached to be parallel to each other. The second cover 125 is a protective member that covers the second imaging substrate 122 from the z axis + side.

  Inside the stay 7, a power supply board 8, a control board 9, a flexible cable 10, a first connector 11, and a second connector 12 are installed. The power supply substrate 8 is formed of a resin such as FR4, for example, and is attached to the x axis + side inside the stay 7. A power supply circuit 16 and a main connector 18 are installed on the power supply board 8. A detailed description of the shape of the power supply board 8 and the attachment to the stay 7 will be given later.

  The control board 9 is made of resin such as FR4, for example, and is attached to the x-axis-side inside the stay 7. A processing circuit 17 is installed on the control board 9. A detailed description of the shape of the control board 9 and attachment to the stay 7 will be given later.

  The flexible cable 10 connects the power supply board 8 and the control board 9 and transmits various signals. The first connector 11 connects the power supply board 8 and the first imaging board 112 of the first imaging unit 110 and transmits various signals. The second connector 12 connects the control board 9 and the second imaging board 122 of the second imaging unit 120 to transmit various signals.

  The main connector 18 supplies power from a battery (not shown) mounted on the vehicle to the power supply circuit 16. The power supply circuit 16 supplies the power supplied via the main connector 18 to the processing circuit 17, the first imaging board 112 and the second imaging board 122. The processing circuit 17 receives photoelectric conversion signals from the first image sensor 111 and the second image sensor 121, and calculates a distance to the object using the object recognition process and the above-described triangulation principle. Perform processing. The processing result by the processing circuit 17 is output as a control signal to the vehicle via the main connector 18.

  FIG. 2 shows the internal shape of the stay 7. On the bottom surface 7B of the stay 7, projections 22, 23, 32, 33 (generally referred to as projections 20) projecting toward the z axis + side and screw holes 24, 25, 34, 35 (generically referred to). In this case, it is called a screw hole 30). On the inner wall surface of the stay 7, recesses 51, 52, 53, 54, 55, 56, 57 for fitting the snap fit when the cover 13 is attached (generally referred to as the recess 50) are formed.

  The protrusions 22 and 23 and the screw holes 24 and 25 are used for attaching the power supply board 8 to the stay 7. The protrusions 22 and 23 are installed near the center of the stay 7, and the screw holes 24 and 25 are the stay 7. Near the end of the x-axis + side. The protrusions 32 and 33 and the screw holes 34 and 35 are used to attach the control board 9 to the stay 7. The protrusions 32 and 33 are installed near the center of the stay 7, and the screw holes 34 and 35 are the stays. 7 near the end on the x-axis side. The height of the protrusion 20, that is, the length in the z-axis direction is formed so that the protrusion 20 does not protrude from the upper surface (z-axis + side surface) of each substrate when the power supply substrate 8 and the control substrate 9 are attached. Is done.

  FIG. 3 shows the internal shape of the cover 13. On the upper surface 13U of the cover 13, projections 41, 42, 43, and 44 (generally referred to as projections 40) that project toward the z-axis-side are installed. On the outer wall surface of the cover 13, projections 61, 62, 63, 64, 65, 66, and 67 for fixing the snap fit when the cover 13 is attached to the stay 7 (generally referred to as the projection 60) are installed. When attaching to the stay 7, the recesses 51, 52, 53, 54, 55, 56 and 57 are fitted.

  The protrusions 41 and 42 are members for fixing the power supply substrate 8 from the z-axis + side. When the cover 13 is attached to the stay 7, the protrusions 22 and 23 provided on the stay 7 are respectively along the z-axis direction. So that they are arranged on the same line. The protrusions 43 and 44 are members for fixing the control substrate 9 from the z axis + side. When the cover 13 is attached to the stay 7, the protrusions 32 and 33 provided on the stay 7 are respectively in the z axis direction. It is installed so that it may line up substantially on the same line along.

  With reference to the internal perspective view shown in FIG. 4, the shape of the power supply substrate 8 and attachment to the stay 7 will be described. The power supply substrate 8 is formed in a rectangular shape with the x-axis direction as the longitudinal direction on the xy plane so that it can be attached to the inside of the stay 7. As shown in the figure, the length L1 of the power supply board 8 in the x-axis direction is shorter than the length L0 of the stay 7 in the x-axis direction in order to reduce the area overlapping the bottom surface 7B of the stay 7.

  Openings are respectively provided at the four corners of the power supply substrate 8. Two openings on the x-axis + side of the power supply substrate 8 are attachment holes 61 and 62, which are provided at positions corresponding to the screw holes 24 and 25 installed in the stay 7, respectively. The power supply board 8 is attached by screwing with screws 91 and 92 inserted through the attachment holes 61 and 62 and the screw holes 24 and 25 of the stay 7. In other words, the mounting holes 61 and 62 fix the power supply substrate 8 without having a degree of freedom with respect to a relative length change in the x-axis direction with respect to the stay 7 generated according to a temperature change.

  Two openings on the x-axis side of the power supply substrate 8 are through holes 63 and 64, and are provided at positions corresponding to the protrusions 22 and 23 provided on the stay 7, respectively. When the power supply substrate 8 is attached to the stay 7, the protrusions 22 and 23 installed on the stay 7 are inserted into the through holes 63 and 64, respectively. Since the lengths of the protrusions 22 and 23 in the z-axis direction are formed as described above, the protrusions 22 and 23 do not protrude from the upper surface of the power supply substrate 8.

  The through holes 63 and 64 are processed into an ellipse having a major axis in the x-axis direction. As will be described later, the long diameters of the through holes 63 and 64 are the length (expansion amount) in which the power supply substrate 8 extends in the x-axis direction in response to a temperature change and the length in which the stay 7 extends in the x-axis direction in response to a temperature change. The length in the x-axis direction is determined so as to be longer than the diameters of the protrusions 22 and 23 according to the difference from the height (the amount of expansion).

  Next, the shape of the control board 9 and attachment to the stay 7 will be described. The control board 9 is formed in a rectangular shape with the x-axis direction as the longitudinal direction on the xy plane so that it can be attached to the inside of the stay 7. As shown in FIG. 4, the length L <b> 2 of the control board 9 in the x-axis direction is shorter than the length L <b> 0 of the stay 7 in the x-axis direction in order to reduce the area overlapping the bottom surface 7 </ b> B of the stay 7. In the present embodiment, the sum of the length L2 of the control board 9 in the x-axis direction and the length L1 of the power supply board 8 in the x-axis direction is greater than the length L0 of the stay 7 in the x-axis direction. Is also formed to be shorter. In other words, the substrate included in the stereo camera device 100 of the present embodiment is configured by being divided by the power supply substrate 8 and the control substrate 9 as two partial substrates. The substrate may be divided by three or more partial substrates according to the length of the stay 7 in the x-axis direction.

  Openings are respectively provided at the four corners of the control substrate 9. Two openings on the x-axis side of the control board 9 are mounting holes 71 and 72, which are provided at positions corresponding to the screw holes 34 and 35 provided in the stay 7, respectively. The control board 9 is attached by screwing with screws 93 and 94 inserted through the attachment holes 71 and 72 and the screw holes 34 and 35 of the stay 7. In other words, the mounting holes 71 and 72 fix the control board 9 without having a degree of freedom with respect to a relative length change in the x-axis direction with respect to the stay 7 generated in accordance with a temperature change.

  Two openings on the x axis + side of the control substrate 9 are through holes 73 and 74, which are provided at positions corresponding to the protrusions 32 and 33 provided on the stay 7, respectively. When the control board 9 is attached to the stay 7, the protrusions 32 and 33 installed on the stay 7 are inserted into the through holes 73 and 74, respectively. Since the lengths of the protrusions 32 and 33 in the z-axis direction are formed as described above, the protrusions 32 and 33 do not protrude from the upper surface of the control substrate 9.

  The through holes 73 and 74 are processed into an ellipse having a major axis in the x-axis direction, like the through holes 63 and 64. As will be described later, the long diameters of the through holes 73 and 74 are such that the control substrate 9 extends in the x-axis direction according to a temperature change (expansion amount) and the stay 7 extends in the x-axis direction according to a temperature change. Depending on the difference from the length (expansion amount), the length in the x-axis direction is determined to be longer than the diameters of the protrusions 32 and 33. That is, in other words, the through holes 73 and 74 fix the control substrate 9 with a degree of freedom with respect to a relative length change in the x-axis direction with respect to the stay 7 generated according to a temperature change.

  Hereinafter, a method for determining the length of the major axis along the x-axis direction of the through holes 63, 64, 73, and 74 will be described. The length of the major axis is determined for the purpose of preventing the stay 7 from warping due to a difference between the linear expansion coefficient of the power supply board 8 or the control board 9 and the linear expansion coefficient of the stay 7 due to temperature change. . The following description will be made with respect to the long diameters of the through holes 73 and 74 provided in the control board 9, but the length of the long diameter is similarly determined for the through holes 63 and 64 provided in the power supply board 8.

The lengths of the long diameters of the through holes 73 and 74 are determined based on the difference between the expansion amount of the control substrate 9 in the x-axis direction and the expansion amount of the stay 7 in the x-axis direction. The expansion amount ΔL2 of the control board 9 and the expansion amount ΔL0 of the stay 7 overlapping with the control board 9 are calculated using the following equation (1).
ΔL2 = α1 × L2 × ΔT
ΔL0 = α0 × L2 × ΔT (1)
ΔT represents a change in temperature, and α1 and α0 represent linear expansion coefficients at normal temperature and general ordinary purity, which the materials of the control substrate 9 and the stay 7 have, respectively. As described above, since the stay 7 is made of aluminum, the linear expansion coefficient α1 is 23.5 × 10 ⁻⁶ [/ ° C.], and since the control substrate 9 is made of FR4, the linear expansion coefficient α0. Is 15 × 10 ⁻⁶ [/ ° C.].

Using the control board 9 calculated by the above equation (1) and the expansion amounts ΔL2 and ΔL0 of the stay 7, the difference D of the expansion amount can be calculated as in the following equation (2).
D = | ΔL0−ΔL2 | (2)

The long diameters of the through holes 73 and 74 are set to be longer than the diameters of the protrusions 32 and 33 inserted therein by at least the difference D of the expansion amount calculated by the equation (2) on the x axis + side and the − side, respectively. To do. Even if the stay 7 and the control substrate 9 expand in the x-axis direction due to the temperature change and the lengths L0 and L2 in the x-axis direction change, the projections 32 and 33 are Relative movement along the x-axis direction is possible. If the stay 7 can be moved relative to the control substrate 9 along the x-axis direction by the difference D of the expansion amount, it is possible to prevent the stay 7 from warping due to the difference in the linear expansion coefficient. Therefore, the length Q of the major axis of the through holes 73 and 74 can be determined so as to satisfy the following formula (3).
Q ≧ d + 2D (3)
Here, d is the diameter of the protrusions 32 and 33 inserted into the through holes 73 and 74.

  When the length L2 of the control substrate 9 in the x-axis direction is 200 [mm] and the temperature is 85 [° C.], the major axis length Q of the through holes 73 and 74 can be determined as follows. The expansion amount ΔL0 of the stay 7 and the expansion amount ΔL2 of the control substrate 9 are 0.28 [mm] and 0.18 [mm], respectively, from the equation (1). In this case, the expansion amount difference D is 0.1 [mm] according to the equation (2). Therefore, the length Q of the long diameter of the through holes 73 and 74 is determined to be longer than the diameter of the protrusions 32 and 33 by at least 0.1 [mm] on the x axis + side and − side, respectively. In particular, it is preferable to take a margin and increase the length Q of the long diameter of the through holes 73 and 74 by 1 [mm] on the x-axis + side and − side, respectively.

  After the power supply board 8 and the control board 9 having the above-described configuration are attached to the stay 7, the protrusion 60 of the cover 13 is fitted into the recess 50 of the stay 7 and the cover 13 is attached to the stay 7. Since the cover 13 is provided with the projection 40 protruding on the z-axis side as described above, the power supply substrate 8 and the control substrate 9 are z through the through holes 71, 72, 73 and 74, respectively. It is urged by the cover 13 from the axis + direction. As a result, the power supply board 8 and the control board 9 are fixed to the stay 7 and, when vibration is applied to the stereo camera device 100, generation of noise due to vibration can be suppressed.

  Instead of the projection 20 provided on the bottom surface 7B of the stay 7 described above, a screw hole may be provided and the power supply board 8 and the control board 9 may be attached by screwing. In this case, it is preferable to screw the rubber washer between the screw hole and the power supply board 8 and the control board 9.

According to the stereo camera device according to the embodiment described above, the following operational effects can be obtained.
(1) The substrate attached to the stay 7 was divided into two partial substrates, a power supply substrate 8 and a control substrate 9. As shown in Expression (1), the amount of expansion due to temperature change increases in proportion to the length of the substrate attached to the stay 7 in the x-axis direction. For this reason, when a single rectangular substrate having a long side along the longitudinal direction of the stay 7 is attached, the difference in the amount of expansion in the longitudinal direction between the stay 7 and the substrate increases, and the stay 7 warps. Occurs, and a deviation occurs between the optical axis of the first lens 113 and the optical axis of the second lens 123. On the other hand, according to the present embodiment, by dividing the power supply board 8 and the control board 9, the length of each board attached to the stay 7 in the x-axis direction is shortened, and the stay 7 And the area where each substrate overlaps is reduced. As a result, it is possible to suppress the warp from occurring in the stay 7, so that the deviation between the optical axis of the first lens 113 and the optical axis of the second lens 123 is suppressed. Therefore, the first and second imaging units 110 and 120 can acquire an image in which the occurrence of deviation in the vertical direction and the rotation direction is reduced, and the reduction of the unacceptable processing of the recognition processing and the distance calculation processing is achieved. Contributes to improvement. Moreover, by dividing the substrate into a plurality of parts, it is possible to ensure solderability when attaching components to both ends in the longitudinal direction.

  Further, each of the power supply board 8 and the control board 9 has through holes 63, 64 and 73, 74 for fixing the stay 7 with flexibility in the longitudinal direction, and the longitudinal direction with respect to the stay 7. Mounting holes 61, 62 and 71, 72 for fixing without having a degree of freedom. Therefore, even if the power supply board 8 and the control board 9 and the stay 7 are expanded in the x-axis direction due to a temperature change, the power supply board 8 and the control board 9 and the stay 7 can move relative to each other along the x-axis direction. 7 can be prevented from occurring. As a result, the first and second imaging units 110 and 120 can acquire an image in which the occurrence of deviation in the vertical direction and the rotation direction is reduced, and the processing accuracy of the recognition processing and the distance calculation processing is reduced. It contributes to the improvement.

(2) The through holes 63, 64, 73 and 74 have a long diameter based on the respective linear expansion coefficients of the stay 7, the power supply substrate 8 and the control substrate 9 along the longitudinal direction, and the diameter of the protrusion 20. The longer diameters of the through holes 63, 64, 73, and 74 are made longer. As a result, with a simple configuration, the relative movement of the power supply substrate 8 and the control substrate 9 and the stay 7 along the x-axis direction is ensured, and the optical axis of the first lens 113 and the optical axis of the second lens 123 are Can be suppressed.

(3) The light receiving surface of the first image sensor 111 and the light receiving surface of the second image sensor 121 are parallel, the optical axis of the first lens 113 and the light receiving surface of the first image pickup 111 are orthogonal, and the second lens The first imaging unit 110 and the second imaging unit 120 are fixed to the stay 7 so that the optical axis 121 and the light receiving surface of the second imaging element 121 are orthogonal to each other. Therefore, the first and second imaging units 110 and 120 can acquire an image in which the occurrence of deviation in the vertical direction and the rotation direction is reduced, and the reduction of the unacceptable processing of the recognition processing and the distance calculation processing is achieved. Contributes to improvement.

  The stereo camera device 100 according to the above-described embodiment has been described as an in-vehicle camera mounted on a vehicle. However, a mobile device such as a construction machine or a railway vehicle, or a camera device mounted on an industrial robot is also included in one embodiment of the present invention.

  As long as the characteristics of the present invention are not impaired, the present invention is not limited to the above-described embodiments, and other forms conceivable within the scope of the technical idea of the present invention are also included in the scope of the present invention. .

7 ... Stay, 8 ... Power supply board, 9 ... Control board, 13 ... Cover,
20, 22, 23, 32, 33 ... projections,
24, 25, 30, 34, 35 ... screw holes,
63, 64, 73, 74 ... through holes,
100 ... Stereo camera device,
110: First imaging unit, 111: First imaging element, 112: First imaging substrate,
113 ... 1st lens, 114 ... 1st imaging housing, 120 ... 2nd imaging unit,
121 ... 2nd imaging element, 122 ... 2nd imaging substrate, 123 ... 2nd lens,
124: Second imaging housing

Claims (3)

A first imaging housing to which a first imaging unit that captures a subject image via a first optical member is attached;
A second imaging housing to which a second imaging unit that captures a subject image via the second optical member is attached;
A substrate provided with a circuit for processing signals output from the first imaging unit and the second imaging unit;
A stay extending in the longitudinal direction,
The first imaging housing is fixed to one end of the stay in the longitudinal direction,
The second imaging housing is fixed to the other end of the stay in the longitudinal direction,
The substrate is composed of a partial substrate divided into a plurality along the longitudinal direction of the stay, and each of the partial substrates is fixed to the stay with a degree of freedom in the longitudinal direction. An in-vehicle stereo camera comprising: a first hole; and a second hole for fixing the stay without having a degree of freedom in the longitudinal direction. The in-vehicle stereo camera according to claim 1,
The first hole has a major axis based on an expansion coefficient of each of the stay and the partial substrate along the longitudinal direction,
The in-vehicle stereo camera, wherein the stay has a protrusion having a diameter shorter than the long diameter of the first hole at a position corresponding to the first hole. The in-vehicle stereo camera according to claim 1 or 2,
The first imaging housing has a first reference surface for attaching the first imaging unit,
The second imaging housing has a second reference surface for attaching the second imaging unit,
In the first imaging housing and the second imaging housing, the first reference surface and the second reference surface are parallel, and the optical axis of the first optical member and the first reference surface are orthogonal to each other. The vehicle-mounted stereo camera is fixed to the stay so that the optical axis of the second optical member and the second reference plane are orthogonal to each other.

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