Imaging device

Abstract

To provide an imaging device which has a low failure risk and cost, and can reduce optical axis deviation.SOLUTION: The imaging device comprises: an imaging element; a housing for holding the imaging element; a member having a linear expansion coefficient different from the housing; and a plurality of fixing parts for fixing the member to the housing. The housing has a component accommodation part that forms a space in which an electrical component is accommodated. The component accommodation part is provided at a position offset in a longer direction of the housing, using a center line of the housing passing through the center of the housing and extending along a short direction of the housing as a reference, with an imaging direction taken as forward. The plurality of fixing parts include a first rear-side fixing part and a second rear-side fixing part for fixing the rear side of the member to the housing. The first rear-side fixing part is arranged in the offset direction of the component accommodation part, using the component accommodation part as a reference. The second rear-side fixing part is arranged in a direction opposite the offset direction of the component accommodation part, using the component accommodation part as a reference. A distance from the center line to the second rear-side fixing part is shorter than a distance from the center line to the first rear-side fixing part.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to an imaging device.

Background Art

[0002] In recent years, aiming at realizing a safe and comfortable automotive society, the installation of driver assistance systems in vehicles has been progressing. Among them, there are systems that pursue the safety, convenience, and comfort of drivers and passengers, such as a collision damage mitigation braking device that automatically decelerates and stops the vehicle before colliding with an obstacle, a vehicle-to-vehicle automatic control device that automatically follows while maintaining a safe distance from the preceding vehicle, a lane departure suppression device, and sign recognition. As such a system, for example, an external recognition system that recognizes vehicles, pedestrians, etc. and measures the distance to the object is known.

[0003] As an external recognition system, a system equipped with a stereo camera (imaging device) is known. In this external recognition system, feature points common to the mutual images are extracted from the information of a pair of images captured by the stereo camera, and a process of obtaining the number of pixels (parallax) by which the positions of the feature points are shifted between the pair of images is performed by an integrated circuit to calculate the distance. Therefore, if there is a shift other than the original parallax between the pair of images, an error will occur in the distance measurement result. As a cause of the shift, there is optical axis shift due to thermal deformation caused by the difference in the amount of expansion of each member during temperature rise due to sunlight or heat generation from electrical components in the imaging device. Optical axis shift refers to the optical axis (center) of optical components such as lenses and imaging elements being inclined or offset with respect to the design reference position.

[0004] Techniques for preventing a decrease in measurement accuracy due to thermal deformation (expansion and contraction) of the housing caused by temperature changes are known (see Patent Document 1). Patent Document 1 discloses a structure in which a housing (camera case) holds a substrate via a pressing member (spring cylinder, air cylinder).

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2019-201262 [Summary of the Invention] [Problems to be Solved by the Invention]

[0006] An imaging device may be formed in an asymmetric shape in order to reduce its size. When the housing of the imaging device is formed in an asymmetric shape, there is a risk that a large deviation may occur in the optical axis of the imaging element fixed to the housing due to thermal deformation of the housing caused by temperature changes. In the technology described in Patent Document 1, a complicated holding structure such as a spring cylinder or an air cylinder is required, resulting in problems of high failure risk and cost.

[0007] An object of the present invention is to provide an imaging device with low failure risk and cost and capable of reducing optical axis deviation. [Means for Solving the Problems]

[0008] An imaging device according to one aspect of the present invention includes an imaging element, a housing that holds the imaging element, a member having a coefficient of linear expansion different from that of the housing and arranged along the longitudinal direction of the housing, and a plurality of fixing parts that fix the member to the housing. The housing has a component storage part that forms a space for storing electrical components. The component storage part is provided at a position offset in the longitudinal direction of the housing with respect to a center line of the housing that extends along the short side direction of the housing passing through the center of the housing with the imaging direction of the imaging element being forward. The housing is formed in an asymmetric shape with respect to the left and right with reference to the center line by having the component storage part. The plurality of fixing parts include a first rear-side fixing part and a second rear-side fixing part that fix the rear side of the member to the housing. The component storage part is arranged between the first rear-side fixing part and the second rear-side fixing part. The first rear-side fixing part is arranged in the offset direction of the component storage part with reference to the component storage part. The second rear-side fixing part is arranged in a direction opposite to the offset direction of the component storage part with reference to the component storage part. The distance from the center line to the second rear-side fixing part is shorter than the distance from the center line to the first rear-side fixing part.

Effects of the Invention

[0009] According to the present invention, it is possible to provide an imaging device with a low risk of failure and low cost, and capable of reducing optical axis deviation.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Figure 4

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Figure 6

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Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that components with the same reference numerals have the same functions. Therefore, unless otherwise specified, if they have already been described, their descriptions will be omitted. The imaging device according to the present embodiment is mounted on a vehicle such as an automobile or a motorcycle. The imaging device continuously captures images of the front of the vehicle and recognizes the position and speed of an object (such as another vehicle or a pedestrian) existing in the traveling direction of the vehicle based on changes in the images over time.

[0012] (First Embodiment) The first embodiment of the present invention will be described with reference to FIGS. 1 to 8. FIG. 1 is an external perspective view of the imaging device 100, and FIG. 2 is a perspective view of the imaging device 100. Note that the x-axis, y-axis, and z-axis shown in the figure represent the three axes of a three-dimensional orthogonal coordinate system. That is, the x-axis, y-axis, and z-axis are orthogonal to each other.

[0013] The z-axis is an axis along the front-rear direction of the imaging device 100 (i.e., the front-rear direction of the vehicle on which the imaging device 100 is mounted). The front in the imaging direction of the imaging device 100 (the imaging direction of the imaging element 2) is defined as positive along the z-axis, and the rear of the imaging device 100 is defined as negative. The y-axis is an axis along the up-down direction of the imaging device 100 (i.e., the up-down direction of the vehicle on which the imaging device 100 is mounted). The upper side of the imaging device 100 is defined as positive along the y-axis, and the lower side of the imaging device 100 is defined as negative. The x-axis is an axis along the left-right direction of the imaging device 100 (i.e., the left-right direction of the vehicle on which the imaging device 100 is mounted). The left side of the imaging device 100 is defined as positive along the x-axis, and the right side of the imaging device 100 is defined as negative.

[0014] As shown in FIGS. 1 and 2, the imaging device 100 includes a rectangular box-shaped housing 101 with an open lower surface (bottom surface) and rear surface (back surface), an imaging module 5 (a first imaging module 5a and a second imaging module 5b) housed inside the housing 101, and a circuit board 107 housed inside the housing 101. The housing 101 is made of metal (e.g., aluminum die-cast), and heat-radiating fins 113 are provided on the upper surface.

[0015] The first imaging module 5a includes a first lens 4a, a first imaging element 2a, a first imaging board 3a on which the first imaging element 2a is mounted, and a first module holder (not shown) that integrally fixes them. The second imaging module 5b includes a second lens 4b, a second imaging element 2b, a second imaging board 3b on which the second imaging element 2b is mounted, and a second module holder (not shown) that integrally fixes them. Hereinafter, the optical axis of the first imaging module 5a (i.e., the optical axes of the first lens 4a and the first imaging element 2a) is referred to as the first optical axis 6a, and the optical axis of the second imaging module 5b (i.e., the optical axes of the second lens 4b and the second imaging element 2b) is referred to as the second optical axis 6b. The first imaging module 5a and the second imaging module 5b are held by the housing 101.

[0016] The imaging substrates (3a, 3b) are connected to the circuit board 107 via a flexible wiring member such as an FPC (flexible printed circuits) or an FFC (flexible flat cable). The circuit board 107 processes the images captured by the imaging elements (2a, 2b) of the imaging module 5. The circuit board 107 is formed of a material different from that of the housing 101. For example, the circuit board 107 is composed of a printed circuit board in which an insulating base material containing a synthetic resin such as glass epoxy and a wiring pattern such as a copper foil are laminated. Therefore, the circuit board 107 and the housing 101 have different linear expansion coefficients (thermal expansion rates). In the present embodiment, the linear expansion coefficient of the housing 101 is larger than that of the circuit board 107.

[0017] A plurality of circuit elements (such as the first circuit element 111 and the second circuit element 112) are mounted on the circuit board 107. The first circuit element 111 has a microcomputer, a signal processing element, an FPGA (Field Programmable Gate Array), an ASIC (Application Specific Integrated Circuit), etc. for processing image signals. The second circuit element 112 has a memory used for temporarily storing data, etc. Note that the plurality of circuit elements may include circuit elements that perform various signal processes such as an MPU (Micro Processing Unit), and large circuit elements such as capacitors.

[0018] The openings on the lower surface and the rear surface of the housing 101 are closed by a cover (not shown) formed of aluminum or the like after the imaging module 5 and the circuit board 107 are mounted on the housing 101. The circuit board 107 and the imaging substrate 3 are surrounded by the metal housing 101 and the covers (the lower surface cover and the rear surface cover). Thereby, the dustproof property of the imaging device 100 is ensured and the electrical influence from the outside to the inside of the imaging device 100 can be blocked (electromagnetic field countermeasures). Further, heat dissipation fins 113 are provided on the metal housing 101. Therefore, the imaging device 100 is also excellent in heat dissipation to the outside.

[0019] The circuit board 107 of the imaging device 100 is electrically connected to the ECU (Electronic Control Unit) of the vehicle. The electrical connection between the imaging device 100 and the ECU is made by connecting a wiring to the electrical connector 114 provided on the upper surface of the circuit board 107. The electrical connector 114 is electrically connected to the wiring pattern of the circuit board 107. Note that an opening for connecting the wiring from the ECU to the electrical connector 114 is provided in the rear cover that covers the opening at the rear of the housing 101. The output signal of the circuit board 107 is transmitted to the ECU via the wiring and is used for vehicle control by the ECU.

[0020] The electrical connector 114 is a relatively large electrical component among the components mounted on the imaging device 100. Therefore, in the present embodiment, a component storage portion 115 for storing the electrical connector 114 attached to the upper surface of the circuit board 107 is formed in the housing 101. The component storage portion 115 functions as a space forming portion that forms a rectangular parallelepiped-shaped space (storage space) for storing the electrical connector 114. The storage space is formed between the circuit board 107 and the housing 101.

[0021] The component storage portion 115 is formed at the rear end of the housing 101. The component storage portion 115 is formed in a rectangular box shape (concave shape) with the bottom surface (lower surface) and the back surface (rear surface) open. The component storage portion 115 has an upper side wall surface facing the upper surface of the electrical connector 114, a right side wall surface 15R (see FIG. 3) facing the right side surface of the electrical connector 114, a left side wall surface 15L (see FIG. 3) facing the left side surface of the electrical connector 114, and a front side wall surface 15F (see FIG. 3) facing the front surface of the electrical connector 114. Note that a gap is formed between the wall surface of the component storage portion 115 and the outer surface of the electrical connector 114.

[0022] Referring to FIG. 3, the arrangement of a plurality of fixing portions 180 for fixing the circuit board 107 to the housing 101 will be described. FIG. 3 is a schematic plan sectional view of the imaging device 100. In FIG. 3, a component storage portion 115 for storing an electrical connector 114 attached to the upper surface of the circuit board 107 is indicated by a two-dot chain line. As shown in FIG. 3, the circuit board 107 is fixed to the housing 101 by a plurality of fixing portions 180. The plurality of fixing portions 180 include a fastening member (not shown) such as a screw, a circular insertion hole provided in the circuit board 107 through which the screw is inserted, and a female screw portion (not shown) provided in the housing 101 with which the screw is screwed. Note that the configuration of the fixing portion 180 is not limited to this. For example, the fixing portion 180 may be configured to be able to fix the circuit board 107 to the housing 101 by means such as riveting or snap fitting, such as crimping or fitting. The plurality of fixing portions 180 include a first rear-side fixing portion 181 and a second rear-side fixing portion 182 that fix the rear side of the circuit board 107 to the rear side of the housing 101. Also, the plurality of fixing portions 180 include a first front-side fixing portion 183 and a second front-side fixing portion 184 that fix the front side of the circuit board 107 to the front side of the housing 101. The first rear-side fixing portion 181 and the first front-side fixing portion 183 are arranged on the right side of the center line 9 of the housing 101, and the second rear-side fixing portion 182 and the second front-side fixing portion 184 are arranged on the left side of the center line 9 of the housing 101.

[0023] The housing 101 has its x-axis direction (left-right direction) as the longitudinal direction. A first imaging module 5a is disposed at one end (right end) in the longitudinal direction of the housing 101. A second imaging module 5b is disposed at the other end (left end) in the longitudinal direction of the housing 101. The circuit board 107 is arranged along the longitudinal direction of the housing 101. The component storage section 115 is arranged on the right side of the center line 9 in the left-right direction of the housing 101. The component storage section 115 is provided at a position offset in the longitudinal direction of the housing 101 with respect to the center line 9 of the housing 101. In the present embodiment, the component storage section 115 exists only on the right side of the center line 9. That is, the left side wall surface 15L, which is the surface of the component storage section 115 closer to the center line 9, is arranged on the right side of the center line 9. The center line 9 extends along the short side direction (z-axis direction) of the housing 101 passing through the center (center in the left-right, up-down, and front-back directions) of the housing 101. The housing 101 is formed in an asymmetrical shape with respect to the left and right with the center line 9 as a reference by having the component storage section 115.

[0024] When the component storage section 115 is provided so as to protrude to the rear of the housing 101, the length of the imaging device 100 in the z-axis direction increases. In the present embodiment, the component storage section 115 is located above the circuit board 107 and does not protrude to the rear of the housing 101. Therefore, the length of the imaging device 100 in the z-axis direction can be shortened.

[0025] Various electrical components are mounted on the circuit board 107. Therefore, it may be difficult to set the position of the electrical connector 114 on the center line 9. In the present embodiment, the electrical connector 114 is arranged at a position offset by a predetermined distance Xo to the right from the center line 9. For this reason, the component storage section 115 is provided at a position offset by a predetermined distance Xo to the right from the center line 9 so that the electrical connector 114 can be stored. That is, the distance Xo from the center line 9 of the housing 101 to the center line of the component storage section 115 that bisects the left-right width of the component storage section 115 corresponds to the offset amount.

[0026] The first rear fixing part 181 and the second rear fixing part 182 are arranged so as to sandwich the component storage part 115 from the left and right. In other words, the component storage part 115 is arranged between the first rear fixing part 181 and the second rear fixing part 182 in the x-axis direction. The first rear fixing part 181 is arranged in the offset direction (i.e., the right direction) of the component storage part 115 with respect to the component storage part 115. The second rear fixing part 182 is arranged in the direction opposite to the offset direction (i.e., the left direction) of the component storage part 115 with respect to the component storage part 115.

[0027] The first front fixing part 183 is provided on an imaginary line parallel to the z-axis direction passing through the first rear fixing part 181. The first front fixing part 183 and the second front fixing part 184 are arranged at symmetric positions with respect to the center line 9 of the housing 101. In contrast, the first rear fixing part 181 and the second rear fixing part 182 are arranged at asymmetric positions with respect to the center line 9. For this reason, the second front fixing part 184 is not provided on an imaginary line parallel to the z-axis direction passing through the second rear fixing part 182.

[0028] The fixing part 180 of the imaging device 100 according to the first embodiment is arranged so as to satisfy the following arrangement conditions. (Arrangement condition 1) The distance B in the x-axis direction from the second rear fixing part 182 to the center line 9 is shorter than the distance A in the x-axis direction from the first rear fixing part 181 to the center line 9.

[0029] Thus, in this embodiment, in the configuration where the component storage part 115 is disposed offset to the right side of the housing 101, by arranging the first rear fixing part 181 and the second rear fixing part 182 such that the distance B from the center line 9 to the second rear fixing part 182 is shorter than the distance A from the center line 9 to the first rear fixing part 181, it is possible to suppress the optical axis deviation.

[0030] The imaging device 100 according to this embodiment is a stereo camera including a pair of left and right imaging modules 5a and 5b. The imaging device 100 captures an image of the front with the pair of left and right imaging modules 5a and 5b, extracts feature points common to the mutual images from the pair of image information, and calculates the number of pixels (parallax) by which the positions of the feature points are shifted between the pair of images by an integrated circuit, and calculates the distance. Therefore, if there is a shift other than the original parallax between the pair of images, an error will occur in the distance measurement result. In addition, with the high performance improvement of the imaging device 100 such as wide-angle conversion, high precision, and high speed response, the allowable amount of shift becomes smaller, and it is necessary to reduce the optical axis shift. The optical axis shift (the shift between the first optical axis 6a of the first imaging module 5a and the second optical axis 6b of the second imaging module 5b) may be caused by thermal deformation due to a difference in the amount of expansion of each member due to a temperature rise caused by heat from the outside such as sunlight or heat generated from electrical components housed inside the housing 101.

[0031] Hereinafter, the effect of suppressing the optical axis shift according to this embodiment will be described with reference to the comparative example of this embodiment. FIG. 4 is a perspective view of the imaging device 900 according to the comparative example of this embodiment, and FIG. 5 is a schematic plan sectional view of the imaging device 900 according to the comparative example of this embodiment. As shown in FIGS. 4 and 5, the imaging device 900 according to the comparative example has the same structure as the imaging device 100 according to this embodiment except for the position of the second rear fixing portion.

[0032] In the imaging device 900 according to the comparative example, four fixing portions for fixing the circuit board 907 to the housing 901 are arranged symmetrically with respect to the left and right. The first rear fixing portion 181 and the second rear fixing portion 982 are arranged symmetrically with respect to the center line 9. The first front fixing portion 183 and the second front fixing portion 184 are arranged symmetrically with respect to the center line 9.

[0033] When the temperature of the imaging device 900 rises, due to the difference in the amount of thermal expansion between the circuit board 907 and the housing 901, the housing 901 undergoes thermal deformation. Hereinafter, the thermal deformation of the housing 901 will be described in detail. The linear expansion coefficient of the housing 901 is larger than that of the circuit board 907. Therefore, when the housing 901 and the circuit board 907 expand due to a temperature increase, forces F1, F2, F3, F4 acting on the housing 901 from the fixing parts 181, 982, 183, 184 toward the center line 9 are applied. When forces F1, F2, F3, F4 act on the housing 901, the housing 901 deforms.

[0034] In the housing 901, a component storage part 115 is formed in the same manner as in the present embodiment. The component storage part 115 forms a space for accommodating an electrical connector 114, which is a relatively large electrical component. The component storage part 115 is formed on the right side of the center line 9 and not on the left side. That is, the housing 901 has an asymmetrical shape with respect to the left and right due to the formation of the component storage part 115. When the housing 901 is formed in a symmetrical shape with respect to the left and right, thermal deformation also occurs symmetrically with respect to the left and right. In contrast, in the comparative example, the rigidity in the vicinity of the component storage part 115 of the housing 901 is different from that of the symmetrical shape configuration. Therefore, in the comparative example, for example, as shown in FIGS. 6 and 7, when the temperature rises, thermal deformation progresses centering around the vicinity of the left side wall surface 15L (see FIG. 15) of the component storage part 115.

[0035] FIG. 6 is a perspective view of the deformed imaging device 900 according to the comparative example, and FIG. 7 is a diagram for explaining the thermal deformation of the imaging device 900 in each direction according to the comparative example. In FIG. 7, (a) schematically shows the deformed imaging device 900 viewed from above, (b) schematically shows the deformed imaging device 900 viewed from the rear, and (c) schematically shows the deformed imaging device 900 viewed from the right.

[0036] As shown in FIG. 6, in the comparative example, when the temperature of the imaging device 900 rises, the housing 901 deforms so as to bend around a deformation center axis 909 passing through the rear end of the left side wall surface 15L of the component storage part 115 and the intersection of the center line 9 of the imaging device 900 and the front end of the imaging device 900. That is, asymmetrical thermal deformation occurs in the housing 901.

[0037] As shown in FIG. 7, the rear part of the imaging device 900 is bent with the center side of the component storage part 115 as the center, and the front part of the imaging device 900 is bent with the vicinity of the center line 9 of the housing 901 as the center. Therefore, torsion and bending occur in the housing 901. As a result, the first imaging module 5a and the second imaging module 5b attached to the housing 901 are not displaced symmetrically and evenly. Thereby, a difference occurs in the displacement and orientation (tilt) of the first optical axis 6a and the second optical axis 6b in the left-right and up-down directions. When such an optical axis deviation occurs, the distance measurement accuracy by the imaging device 900 decreases.

[0038] As described above, in the comparative example, since the housing 901 is deformed asymmetrically in the left-right direction, there is a possibility that a large measurement error may occur. On the other hand, in the present embodiment, the second rear-side fixing portion 182 is located on the right side (center line 9 side) compared to the position of the second rear-side fixing portion 982 of the comparative example (see FIGS. 3 and 5). That is, the position of the second rear-side fixing portion 182 of the present embodiment is closer to the component storage portion 115 than the position of the second rear-side fixing portion 982 of the comparative example. Therefore, in the present embodiment, when the temperature of the imaging device 100 rises, the rear part of the housing 101 is deformed symmetrically in the left-right direction with the center line 9 as the center. That is, the front part and the rear part of the housing 101 are deformed in a balanced manner symmetrically with the center line 9 as the center. Thereby, in the present embodiment, the optical axis deviation is suppressed.

[0039] FIG. 8 is a diagram showing the relationship between the relative displacement of the first optical axis 6a and the second optical axis 6b when a predetermined temperature change occurs and the distance B from the center line 9 of the housing 101 to the second rear-side fixing portion 182. In FIG. 8, the horizontal axis represents the distance B from the center line 9 to the second rear-side fixing portion 182. The vertical axis represents the relative displacement, which is the difference between the displacement of the first optical axis 6a and the displacement of the second optical axis 6b caused by the thermal deformation of the housing 101 due to the temperature change.

[0040] As shown in FIG. 8, in the range where the distance is equal to or greater than distance B1 and equal to or less than distance A, the relative displacement decreases as the distance B decreases. When the distance B is equal to distance B1, the relative displacement becomes 0 (zero). In the range where the distance is equal to or greater than 0 and equal to or less than distance B1, the relative displacement (absolute value) increases as the distance B decreases. The relationship shown in FIG. 8 is obtained in advance by experiments or the like. The relative displacement shown in FIG. 8 is, as an example, the difference between the angular displacement in the yz plane of the first optical axis 6a (i.e., the amount of change in the angle around the x-axis) and the angular displacement in the yz plane of the second optical axis 6b (i.e., the amount of change in the angle around the x-axis), that is, it corresponds to the angle formed by the first optical axis 6a and the second optical axis 6b in the yz plane.

[0041] As shown in FIG. 8, the distance B is a predetermined value B1 that is smaller than the value of distance A and greater than 0, and the relative displacement becomes the minimum value (for example, 0). Thus, there exists an optimal value (predetermined value B1) for the distance B that has a high effect of reducing the optical axis deviation. For this reason, it is preferable to determine the optimal value (predetermined value B1) in advance by experiments or the like and reflect it in the design of the actual product.

[0042] In the present embodiment, as described above, the component storage unit 115 is provided at the rear part of the imaging device 100. The component storage unit 115 is provided at a position offset to the right from the center line 9. Based on the component storage unit 115, a first rear-side fixing portion 181 for fixing the rear part of the circuit board 107 to the housing 101 is provided in the offset direction (right direction) of the component storage unit 115. Based on the component storage unit 115, a second rear-side fixing portion 182 for fixing the rear part of the circuit board 107 to the housing 101 is provided in the direction opposite to the offset direction of the component storage unit 115 (left direction). The second rear-side fixing portion 182 is arranged such that the distance B between the second rear-side fixing portion 182 and the center line 9 of the housing 101 is shorter than the distance A between the first rear-side fixing portion 181 and the center line 9 of the housing 101 (distance B < distance A). With this arrangement, when the temperature of the imaging device 100 rises, the housing 101 can be deformed symmetrically about the center line 9. That is, with the above arrangement, the deformation central axis of the housing 101 can be brought closer to the center line 9. Thereby, the displacements of the first imaging module 5a and the second imaging module 5b are balanced.

[0043] Thus, in this embodiment, by making the change amount of the first optical axis 6a substantially coincide with the change amount of the second optical axis 6b with respect to disturbances such as temperature changes, the optical axis deviation can be reduced. In particular, the effect of reducing the optical axis deviation in the vertical direction (y direction) of the imaging device 100 is high. As a result, since the accuracy of measurement such as the distance from the imaging device 100 to the object imaged by the imaging device 100 is improved, a highly reliable imaging device 100 can be provided.

[0044] Also, according to this embodiment, there is no need to provide a complicated holding structure such as a spring cylinder or an air cylinder described in Patent Document 1. By attaching the circuit board 107 to the housing 101 via a rubber washer or the like, there is no need to absorb the difference in thermal expansion between the circuit board 107 and the housing 101. That is, according to this embodiment, no additional parts such as a complicated holding structure and a rubber washer are required. Therefore, the failure risk and cost of the imaging device 100 can be reduced.

[0045] Furthermore, according to this embodiment, an arbitrary shape can be adopted without considering the symmetry of the housing 101, and a component arrangement suitable for miniaturization of the imaging device 100 becomes possible. That is, a small-sized imaging device 100 can be provided.

[0046] According to the above-described embodiment, the following operational effects are achieved.

[0047] The imaging device 100 includes imaging elements 2a and 2b, a housing 101 that holds the imaging elements 2a and 2b, a circuit board (member) 107 that has a coefficient of linear expansion different from that of the housing 101 and is arranged along the longitudinal direction of the housing 101, and a plurality of fixing parts 180 that fix the circuit board 107 to the housing 101. The housing 101 has a component storage part 115 that forms a space for housing an electrical connector (electrical component) 114. The component storage part 115 is provided at a position offset in the longitudinal direction (x-axis direction) of the housing 101 with respect to the center line 9 of the housing 101 that extends along the short-side direction (z-axis direction) of the housing 101 passing through the center of the housing 101 with the imaging direction of the imaging elements 2a and 2b being forward. The housing 101 is formed in an asymmetric shape with respect to the left and right with the center line 9 as a reference by having the component storage part 115. The plurality of fixing parts 180 include a first rear-side fixing part 181 and a second rear-side fixing part 182 that fix the rear side of the circuit board 107 to the housing 101. The component storage part 115 is arranged between the first rear-side fixing part 181 and the second rear-side fixing part 182. The first rear-side fixing part 181 is arranged in the offset direction of the component storage part 115 (in the right direction (-x direction) in the example shown in FIG. 3) with respect to the component storage part 115. The second rear-side fixing part 182 is arranged in the direction opposite to the offset direction of the component storage part 115 (in the left direction (+x direction) in the example shown in FIG. 3) with respect to the component storage part 115. The distance B from the center line 9 to the second rear-side fixing part 182 is shorter than the distance A from the center line 9 to the first rear-side fixing part 181. According to this configuration, an imaging device 100 with a low risk of failure and low cost and capable of reducing optical axis deviation can be provided.

[0048] (Second Embodiment) With reference to FIG. 9, the imaging device 200 according to the second embodiment of the present invention will be described. Note that the same or corresponding components as those described in the first embodiment are denoted by the same reference numerals, and the differences will be mainly described. FIG. 9 is a diagram similar to FIG. 3 and is a schematic plan sectional view of the imaging device 200 according to the second embodiment.

[0049] In this second embodiment, as shown in FIG. 9, the first rear fixing portion 181 and the second rear fixing portion 182 are arranged such that the distance C to a line passing through a predetermined position (predetermined point) P in the component storage portion 115 and parallel to the center line 9 is equal. In other words, the first rear fixing portion 181 and the second rear fixing portion 182 are arranged at positions that are symmetric with respect to the left and right with reference to the predetermined position P in the component storage portion 115. That is, the fixing portion 180 of the imaging device 200 according to this second embodiment is arranged so as to satisfy the following two arrangement conditions. (Arrangement condition 1) The distance B in the x-axis direction from the second rear fixing portion 182 to the center line 9 is shorter than the distance A in the x-axis direction from the first rear fixing portion 181 to the center line 9. (Arrangement condition 2A) The distance C in the x-axis direction from the first rear fixing portion 181 to the predetermined position P in the component storage portion 115 is equal to the distance C in the x-axis direction from the second rear fixing portion 182 to the predetermined position P.

[0050] In this embodiment, the distance B is the optimum value (predetermined value) B1 at which the effect of optical axis deviation is the greatest. Also, the predetermined position P corresponds to the rear end of the left side wall surface 15L of the component storage portion 115 that is the starting point of deformation in the comparative example (see FIG. 7).

[0051] As described above, in this second embodiment, the first rear fixing portion 181 and the second rear fixing portion 182 are arranged such that the distances to a line L passing through the inside of the component storage portion 115 and parallel to the center line 9 of the housing 101 are equal. According to this second embodiment, the same operational effects as those of the first embodiment can be obtained. Also, according to this second embodiment, optical axis deviation can be reduced as compared with the case where the second rear fixing portion 182 is located on the left side of the example shown in FIG. 9.

[0052] (Third Embodiment) With reference to FIG. 10, the imaging device 300 according to the third embodiment of the present invention will be described. Note that the same reference numerals are given to the same or corresponding configurations as those described in the first embodiment, and the differences will be mainly described. FIG. 10 is a diagram similar to FIG. 3 and is a schematic cross-sectional plan view of the imaging device 300 according to the third embodiment.

[0053] In the third embodiment, as shown in FIG. 10, the plurality of fixing portions 180 are arranged such that the distance E between the first rear fixing portion 181 and the second rear fixing portion 182 is shorter than the distance D between the first front fixing portion 183 and the second front fixing portion 184 (distance E < distance D). That is, the fixing portion 180 of the imaging device 300 according to the third embodiment is arranged to satisfy the following two arrangement conditions. (Arrangement condition 1) The distance B in the x-axis direction from the second rear fixing portion 182 to the center line 9 is shorter than the distance A in the x-axis direction from the first rear fixing portion 181 to the center line 9. (Arrangement condition 2B) The distance E in the x-axis direction from the first rear fixing portion 181 to the second rear fixing portion 182 is shorter than the distance D in the x-axis direction from the first front fixing portion 183 to the second front fixing portion 184.

[0054] As described above, the imaging device 300 is formed in a box shape with the rear surface of the housing 101 open in order to attach components such as the imaging module 5 and the circuit board 107 to the housing 101. The rear surface (open surface) of the housing 101 is closed by a rear cover after the components are attached to the housing 101. The thickness of the rear cover is thinner than that of the front panel of the housing 101. Therefore, the rear cover has lower rigidity than the front panel of the housing 101.

[0055] Since the rear side of the housing 101 is open, the rigidity of the rear side is lower than that of the front side. Therefore, in the above-described comparative example (see FIG. 7), when a temperature change occurs, if substantially the same force acts on the housing 101 from each fixing portion 180, thermal deformation (see FIG. 7(a)) in which the housing 101 having a rectangular shape in the xz plane bulges forward occurs. As a result, an optical axis shift in the x-axis direction occurs.

[0056] In contrast, in the third embodiment, the distance E between the rear fixing portions 181 and 182 adjacent to each other in the left - right direction is shorter than the distance D between the front fixing portions 183 and 184 adjacent to each other in the left - right direction. The force generated by the thermal expansion difference increases as the distance between the fixing portions becomes longer. Therefore, compared with the forces (inward forces) F3 and F4 applied from the front fixing portions 183 and 184 toward the center line 9 at the front portion of the housing 101, the forces (inward forces) F1 and F2 applied from the rear fixing portions 181 and 182 toward the center line 9 at the rear portion of the housing 101 become smaller. Thereby, it is possible to suppress the deformation of the housing 101 that becomes convex forward as shown in FIG. 7(a). As a result, mainly, the effect of reducing the optical axis deviation in the left - right direction (x - axis direction) of the imaging device 100 can be enhanced.

[0057] As described above, the imaging device 300 according to the third embodiment includes, as a plurality of fixing portions 180, a plurality of front fixing portions 183 and 184 that fix the front side of the circuit board (member) 107 to the housing 101, and a plurality of rear fixing portions 181 and 182 that fix the rear side of the circuit board (member) 107 to the housing 101. The distance E between the first rear fixing portion 181 and the second rear fixing portion 182 adjacent to each other in the x - axis direction is shorter than the distance D between the front fixing portions 183 and 184 adjacent to each other in the x - axis direction. According to this configuration, the same operational effects as those of the first embodiment can be obtained. Also, according to the third embodiment, the effect of reducing the optical axis deviation in the left - right direction (x - axis direction) of the imaging device 100 can be further enhanced.

[0058] (Modification of the Third Embodiment) When three or more front fixing portions are provided, the distance E between the first rear fixing portion 181 and the second rear fixing portion 182 may be configured to be shorter than the maximum value Dmax of the distances between the front fixing portions adjacent to each other in the x - axis direction. Also, when three or more rear fixing portions are provided in addition to the front fixing portions, the maximum value Emax of the distances between the rear fixing portions adjacent to each other in the x - axis direction may be configured to be shorter than the maximum value Dmax of the distances between the front fixing portions adjacent to each other in the x - axis direction.

[0059] (Fourth Embodiment) Referring to FIG. 11, the imaging device 400 according to the fourth embodiment of the present invention will be described. Note that the same or corresponding components as those described in the first embodiment are denoted by the same reference numerals, and the differences will be mainly described. FIG. 11 is a diagram similar to FIG. 3 and is a schematic plan sectional view of the imaging device 400 according to the fourth embodiment. Note that in FIG. 11, the illustration of the component storage portion 115 is omitted.

[0060] In this fourth embodiment, as shown in FIG. 11, a notch 407a is provided at the rear portion of the circuit board 407. The notch 407a is between the first rear-side fixing portion 181 and the second rear-side fixing portion 182 and is provided on the line connecting the center of the first rear-side fixing portion 181 and the center of the second rear-side fixing portion 182. The notch 407a is a concave opening that recesses forward from the rear end edge of the circuit board 407. The notch 407a is provided on the center line 9 of the housing 101 and is formed in a bilaterally symmetric shape with respect to the center line 9.

[0061] In this fourth embodiment, when the temperature rises, the deformation of the circuit board 407 progresses centering on the notch 407a of the circuit board 407, and the extension of the rear portion of the circuit board 407 becomes larger than that of the front portion as the circuit board 407. That is, the extension amount of the rear portion of the circuit board 407 can be made closer to the extension amount of the rear portion of the housing 101. For this reason, the force applied from the circuit board 407 to the housing 101 is smaller at the rear portion than at the front portion. In the box-shaped housing 101 with an open rear surface, since the force acting on the rear portion of the housing 101 can be reduced, the effect of reducing the optical axis deviation in the left-right direction (x-axis direction) of the imaging device 100 can be enhanced as in the third embodiment.

[0062] According to such a fourth embodiment, the same operational effects as those of the first embodiment are achieved. Further, in the imaging device 400 according to the fourth embodiment, a notch (opening) 407a is provided between the first rear-side fixing portion 181 and the second rear-side fixing portion 182 in the circuit board (member) 407. For this reason, the effect of reducing the optical axis deviation in the left-right direction (x-axis direction) of the imaging device 100 can be enhanced as in the third embodiment.

[0063] (Modification of the Fourth Embodiment) The position of the notch 407a is not limited to being provided on the center line 9. The notch 407a may be provided at a position away from the center line 9. The notch 407a may be provided at least between the first rear fixing portion 181 and the second rear fixing portion 182. Also, two or more notches 407a may be provided.

[0064] (Fifth Embodiment) Referring to FIG. 12, the imaging device 500 according to the fifth embodiment of the present invention will be described. Note that the same reference numerals are given to the same or corresponding configurations as those described in the first embodiment, and the differences will be mainly described. FIG. 12 is a schematic rear cross-sectional view of the fixing portion 180 of the imaging device 500 according to the fifth embodiment. The configurations of the plurality of fixing portions 180 are the same. Therefore, the configuration of the fixing portion 180 will be described by taking the first rear fixing portion 181 shown in FIG. 12 as a representative.

[0065] As shown in FIG. 12, the fixing portion 180 includes a boss (hereinafter also referred to as a housing boss) 585 provided on the housing 101, a boss (hereinafter also referred to as a cover boss) 586 provided on the lower surface cover 102, and a screw 587. The housing boss 585 protrudes downward from the upper surface plate of the housing 101. The cover boss 586 protrudes upward from the lower surface cover 102. The lower surface cover 102 is a rectangular plate-shaped cover that closes the lower surface (bottom surface), which is the open surface of the housing 101. The lower surface cover 102 is disposed opposite to the upper surface plate of the housing 101. The lower surface cover 102 is disposed along the longitudinal direction of the housing 101.

[0066] A female screw portion is formed on the housing boss 585. The male screw portion of the screw 587 is screwed into the female screw portion. A concave portion (deep counterbore) 586a with an open lower surface is provided on the cover boss 586. The head of the screw 587 is accommodated in the concave portion 586a. Thereby, the screw 587 is prevented from protruding from the lower surface cover 102.

[0067] The screw 587 is inserted through the through-hole of the cover boss 586 and the through-hole of the circuit board 107 from below, and is screwed into the internal thread portion of the housing boss 585. As a result, the circuit board 107 is sandwiched in the vertical direction by the housing boss 585 and the cover boss 586. In the present embodiment, in each of the plurality of fixing portions 181 to 184, the circuit board 107 is sandwiched by a pair of bosses (585, 586). That is, the first rear fixing portion 181 fixes the circuit board 107 to the housing 101 and the lower cover 102 at the same location, the second rear fixing portion 182 fixes the circuit board 107 to the housing 101 and the lower cover 102 at the same location, the first front fixing portion 183 fixes the circuit board 107 to the housing 101 and the lower cover 102 at the same location, and the second front fixing portion 184 fixes the circuit board 107 to the housing 101 and the lower cover 102 at the same location.

[0068] The imaging device 900 according to the above-described comparative example (see FIG. 7) had a two-layer structure in which the housing 101 and the circuit board 107 were fixed by the fixing portion 180. For this reason, the thermal deformation due to the difference in thermal expansion during temperature rise becomes a deformation convex upward (bent in the y direction) due to the bimetal effect (see FIG. 7(b)). As a result, the first imaging module 5a rotates about the first optical axis 6a (rotates clockwise in FIG. 7(b)), and the second imaging module 5b rotates about the second optical axis 6b (rotates counterclockwise in FIG. 7(b)). That is, an optical axis shift occurs in the rotation direction about the optical axis.

[0069] On the other hand, in the present fifth embodiment, as shown in FIG. 12, the housing 101, the circuit board 107, and the lower cover 102 have a three-layer structure in which they are fixed by the fixing portion 180 at the same location. The lower cover 102 is formed of the same material as the housing 101. In this configuration, when the temperature rises, the thermal deformation of the housing 101 and the circuit board 107 (deformation that becomes a convex upward shape) is offset by the thermal deformation of the lower cover 102 and the circuit board 107 (deformation that becomes a convex downward shape). As a result, the thermal deformation of the housing 101 during temperature rise can be reduced, and the optical axis shift of the imaging module 5 attached to the housing 101 can be reduced.

[0070] According to this fifth embodiment, the same operational effects as those of the first embodiment are achieved. Further, the circuit board (member) 107 is disposed between the housing 101 and the bottom cover (cover) 102 facing the housing 101. The plurality of fixing portions 180 fix the circuit board 107 to the housing 101 and the bottom cover 102 at the same location respectively. In this configuration, by adopting a material for the bottom cover 102 that is the same as or has a coefficient of linear expansion close to that of the housing 101, the thermal deformation due to the bimetal effect between the housing 101 and the circuit board 107 can be offset by the thermal deformation due to the bimetal effect between the bottom cover 102 and the circuit board 107. Thereby, particularly, the optical axis deviation in the rotational direction centered on the optical axis can be effectively suppressed. Further, the rigidity of the entire imaging device 500 is increased. Thereby, the thermal deformation of the imaging device 500 is suppressed, and the optical axis deviation in each direction is reduced.

[0071] (Modification Example of the Fifth Embodiment) The configuration in which the circuit board 107 is sandwiched between the housing boss 585 and the cover boss 586 does not have to be applied to all of the four fixing portions 180.

[0072] The housing 101 is formed in a box shape having a wall at the front and an open rear surface. For this reason, the rigidity of the rear portion of the housing 101 is lower than the rigidity of the front portion of the housing 101. Therefore, the two locations of the first rear-side fixing portion 181 and the second rear-side fixing portion 182 may adopt a configuration in which they are sandwiched between the housing boss 585 and the cover boss 586, and the two locations of the first front-side fixing portion 183 and the second front-side fixing portion 184 (all of the plurality of front-side fixing portions) may be configured to fix the circuit board 107 only to the housing 101.

[0073] Thereby, the balance of the rigidity of the front and rear of the imaging device 500 can be achieved. As a result, the optical axis deviation in the left-right direction (x-axis direction) of the imaging device 500 can be effectively reduced.

[0074] The present invention is not limited to the above-described embodiments, and various modifications and combinations within the scope not departing from the gist thereof are included. For example, the following modifications are also within the scope of the present invention, and it is also possible to combine the configurations shown in the modifications with the configurations described in the above embodiments, combine the configurations described in the above different embodiments with each other, or combine the configurations described in the following different modifications with each other.

[0075] <Modification Example 1> In the above embodiment, an example in which all of the component storage unit 115 is arranged on the right side of the center line 9 has been described. However, the component storage unit 115 may be arranged so as to straddle the center line 9. In this case, since the distance from the center line 9 to the left side wall surface 15L of the component storage unit 115 and the distance from the center line 9 to the right side wall surface 15R of the component storage unit 115 are different, the housing 101 is formed in an asymmetrical shape with respect to the left and right.

[0076] <Modification Example 2> In the above embodiment, an example in which the electrical connector 114 is stored in the component storage unit 115 that forms a rectangular parallelepiped-shaped space has been described, but the present invention is not limited thereto. The component storage unit 115 can store various relatively large electrical components such as capacitors attached to the circuit board 107. Note that the component storage unit 115 for storing a cylindrical capacitor may be configured to form a cylindrical space. For example, the component storage unit 115 may be formed in a cylindrical shape.

[0077] <Modification Example 3> In the above embodiment, countermeasures against deformation of the housing 101 due to the difference in thermal expansion between the housing 101 and the circuit board 107 fixed to the housing 101 were exemplified. However, the present invention is not limited to this. When the material of the member fixed to the housing 101 by the plurality of fixing portions 180 is different from that of the housing 101, the optical axis deviation due to thermal deformation described in the above embodiment occurs. The present invention is applicable to deformation of the housing 101 caused by the difference in thermal expansion between the housing 101 and various members fixed to the housing 101. For example, the present invention may be applied when a reinforcing member for reinforcing the housing 101 is attached to the housing 101 and the materials of the housing 101 and the reinforcing member are different. When the housing 101 is formed of an aluminum-based material and the reinforcing member is formed of an iron-based material (for example, stainless steel), a difference in thermal expansion occurs between the two. Further, for example, the present invention may be applied when a resin member for maintaining the waterproofness (airtightness) of the housing 101 is attached to the housing 101. In the above embodiment, an example in which the linear expansion coefficient of the housing 101 is larger than the linear expansion coefficient of the circuit board 107 fixed to the housing 101 was described. However, the present invention may also be applied when the magnitude relationship of the linear expansion coefficients is reversed.

[0078] <Modification Example 4> In the above embodiment, an example in which the imaging device 100 is a stereo camera including two imaging elements 2a and 2b was described. However, the imaging device to which the present invention is applicable is not limited to this. The present invention may be applied to an imaging device having three or more imaging elements 2 and measuring a distance by selecting a plurality of the imaging elements 2. Further, the present invention may be applied to an imaging device having one imaging element 2. In this case, a distance measurement system is configured by a plurality of imaging devices and a processing device that processes image signals from the plurality of imaging devices.

[0079] <Modification Example 5> As an example of the combination of the configurations described in the above different embodiments, a plurality of fixing parts 180 may be arranged so as to satisfy all of (Arrangement condition 1), (Arrangement condition 2A), and (Arrangement condition 2B) described in the first to third embodiments. Further, the notch (opening) 407a described in the fourth embodiment may be provided in the circuit board, or the fixing structure described in the fifth embodiment may be adopted.

[0080] As described above, the embodiments of the present invention have been described. However, the above embodiments merely show a part of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments. The present invention is not limited to those having all the configurations described in the above embodiments, and includes those in which a part of the configurations is deleted.

Explanation of reference numerals

[0081] 2... imaging element, 2a... first imaging element, 2b... second imaging element, 3... imaging substrate, 3a... first imaging substrate, 3b... second imaging substrate, 4a... first lens, 4b... second lens, 5... imaging module, 5a... first imaging module, 5b... second imaging module, 6a... first optical axis, 6b... second optical axis, 9... center line of the housing, 100... imaging device, 101... housing, 102... bottom cover (cover), 107... circuit board (member), 114... electrical connector (electrical component), 115... component storage part, 180... fixing part, 181... first rear fixing part, 182... second rear fixing part, 183... first front fixing part, 184... second front fixing part, 200, 300, 400... imaging device, 407... circuit board (member), 407a... notch (opening), 500... imaging device, 585... housing boss, 586... cover boss

Claims

1. An imaging element, a housing that holds the imaging element, a member having a coefficient of linear expansion different from that of the housing and arranged along the longitudinal direction of the housing, and a plurality of fixing parts that fix the member to the housing, wherein the housing has a component storage part that forms a space for storing electrical components, the component storage part is provided at a position offset in the longitudinal direction of the housing with respect to a center line of the housing that extends along the short-side direction of the housing and passes through the center of the housing with the imaging direction of the imaging element being forward, the housing is formed in an asymmetric shape with respect to the left and right with reference to the center line by having the component storage part, the plurality of fixing parts include a first rear-side fixing part and a second rear-side fixing part that fix the rear side of the member to the housing, the component storage part is arranged between the first rear-side fixing part and the second rear-side fixing part, the first rear-side fixing part is arranged in the offset direction of the component storage part with reference to the component storage part, the second rear-side fixing part is arranged in a direction opposite to the offset direction of the component storage part with reference to the component storage part, a distance from the center line to the second rear-side fixing part is shorter than a distance from the center line to the first rear-side fixing part, an imaging device.

2. In the imaging device according to Claim 1, the first rear-side fixing part and the second rear-side fixing part are arranged such that distances to a line passing through the inside of the component storage part and parallel to the center line are equal, an imaging device.

3. In the imaging device according to Claim 1, the housing is formed in a box shape with an open rear surface, the plurality of fixing parts include a plurality of front-side fixing parts that fix the front side of the member to the housing, a distance between the first rear-side fixing part and the second rear-side fixing part is shorter than a distance between adjacent front-side fixing parts, an imaging device.

4. In the imaging device according to Claim 1, the housing is formed in a box shape with an open rear surface, an opening is provided between the first rear-side fixing part and the second rear-side fixing part in the member, an imaging device.

5. In the imaging device according to Claim 1, the member is arranged between the housing and a cover facing the housing, the first rear-side fixing part and the second rear-side fixing part respectively fix the member to the housing and the cover at the same location, an imaging device.

Images