Imaging device and method for assembling the imaging device

Abstract

To efficiently radiate heat that has occurred in the housing inside of an imaging device.SOLUTION: A heat transfer part projecting in a direction of the object to be heat dissipated is provided to a camera housing so that when a lens barrel for holding an optical element, an imaging element for acquiring a subject image formed by the optical element, a first printed circuit board provided with an image processing circuit for the imaged image having been imaged by the imaging element, and a second printed circuit board on which the imaging element is mounted are accommodated in the camera housing, the heat transfer part faces at least the object to be heat dissipated that is provided to the first printed circuit board. A coating of heat conduction material is applied to the heat transfer part and the first printed circuit is installed in the camera housing before being assembled in such a way that the heat transfer part and the object to be heat dissipated are contacted via the heat conduction material. Thus, the heat generated in the object on the first printed circuit board that is to be heat dissipated is transmitted to the camera housing via the heat conduction material and the heat transfer part, making it possible to efficiently dissipate the heat.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to an imaging device and an assembling method of the imaging device.

Background Art

[0002] Today, when there is a risk of collision based on the relative speed or relative position between a vehicle, an obstacle, a pedestrian, or a worker detected from an image captured by a stereo camera device and the driving vehicle, the driver is alerted, and a driving support device that automatically applies brakes to avoid a collision is known.

[0003] Also, Patent Document 1 (Japanese Unexamined Patent Application Publication No. 2013-114606) discloses an object detection device that improves the detection accuracy of a vehicle or an obstacle. When the relative distance between vehicles is difficult to detect by stereo image processing at a distance where the relative distance between vehicles is far, this object detection device obtains the relative distance between vehicles using one camera device of a stereo camera (monocular image processing). Then, the relative distance calculated by stereo image processing and the relative distance calculated by monocular image processing are switched to obtain other vehicle information.

Summary of the Invention

Problems to be Solved by the Invention

[0004] Here, by increasing the number of pixels of the imaging element of the imaging device, it is possible to improve the detection accuracy of a vehicle or an obstacle. However, when the number of pixels of the imaging element is increased, the amount of information processing of the captured image also increases, the heat generation amount of the imaging element and the image processing circuit increases, and lens displacement is likely to occur. Therefore, the camera housing that holds the lens needs to stably maintain the position and posture of the lens regardless of the passage of time, and efficiently dissipate the heat generated by a printed wiring board or the like provided with the imaging element and the image processing circuit.

[0005] The present invention has been made in view of the above problems, and an object thereof is to provide an imaging device and an assembling method of the imaging device capable of efficiently dissipating heat generated inside the housing.

Means for Solving the Problem

[0006] In order to solve the above-described problems and achieve the object, the present invention provides an imaging device having a lens barrel that holds an optical element, an imaging element for acquiring a subject image formed by the optical element, a first printed circuit board including an image processing circuit for an imaging image captured by the imaging element, a second printed circuit board on which the imaging element is mounted, and a camera housing that holds the lens barrel, the imaging element, the first printed circuit board, and the second printed circuit board, wherein the camera housing includes Holding the lens barrel, the imaging device, and the second printed circuit board a first housing member Sealing the accommodating portion of the first housing member that accommodates the first printed circuit board and the second printed circuit board and a second housing member 、 and includes The second housing member a first heat transfer part that transfers heat generated on the first printed circuit board In the second housing member and has And a second heat transfer portion that transfers the heat generated in the second printed circuit board to the second housing member And the second printed circuit board is fixed to the first housing member via a member having a high thermal resistance so that the heat generated in the second printed circuit board mainly moves to the second housing member .

Advantages of the Invention

[0007] According to the present invention, there is an effect that heat generated inside the housing can be efficiently radiated.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Embodiments for Carrying Out the Invention

[0009] Hereinafter, with reference to the accompanying drawings, a stereo camera device (an example of an imaging device) according to an embodiment will be described. Although it is an example, the stereo camera device according to this embodiment is provided in a moving body such as an automobile, a ship, or an aircraft, and images a vehicle, an obstacle, a pedestrian, or a worker in front (or behind or left and right) of the moving body. The left and right captured images are used for detecting an object such as a vehicle in front of the moving body. When an object is detected, a risk of collision is determined from a relative speed or a relative position with the moving body, and driving support such as alerting a driver or avoiding a collision by an automatic brake is performed.

[0010] (Principle of Distance Measurement) First, FIG. 1 shows a diagram for explaining the principle of distance measurement by a stereo camera device in which left and right monocular camera devices C0 and C1 are arranged in parallel. As shown in this FIG. 1, the camera devices C0 and C1 are installed at a distance B from each other.

[0011] Assuming that the focal lengths of the camera devices C0 and C1 are "f", the optical centers are "O0, O1", and the imaging planes are "s0, s1", the image of the subject A located at a distance d from the optical center O0 of the camera device C0 in the optical axis direction is connected to the image at the intersection point P0 of the straight line A - O0 and the imaging plane s0. On the other hand, in the camera device C1, the same subject A forms an image at the position P1 on the imaging plane s1.

[0012] Here, let the intersection point of the straight line passing through the optical center O1 of the camera device C1 and parallel to the straight line A - O0 (the straight line indicated by the dotted line in FIG. 1) and the imaging plane s1 be P02, and let the distance between this point P02 and the position P1 on the imaging plane s1 be p. P02 is at the same position as the image P0 on the camera device C0, and the distance p represents the amount of displacement (parallax) of the images of the same subject on the images captured by the two camera devices C0 and C1.

[0013] Since the triangles "A - O0 - O1" and "O1 - P02 - P1" are similar, the distance d can be calculated by the arithmetic formula "d = Bf / p". Since the distance B (baseline length) and the focal length f of each camera device C0 and C1 are distances known in advance in terms of design and manufacturing, the distance d from the subject A can be obtained from the parallax p.

[0014] In order to improve the distance measurement accuracy for a long - distance obstacle in triangulation using such a stereo camera device, it is necessary to increase the baseline length, which is the distance between the axes of the camera devices C0 and C1, or to increase the focal lengths of the camera devices C0 and C1. However, if the baseline length is increased, the arrangement between the camera devices C0 and C1 becomes farther apart, the stereo camera device becomes larger, and there is a risk of obstructing the forward field of view when mounted on a vehicle.

[0015] On the other hand, for a short - distance obstacle near the vehicle, it is required to be able to recognize up to the diagonally forward direction of the vehicle. Therefore, in order to image the short - distance obstacle, it is necessary to use a camera device with a wide field of view. However, if the focal length of the camera device is increased to improve the distance measurement accuracy, due to the characteristics of the lens, the measurement accuracy of short - distance obstacles decreases, and the field of view angle of the camera device becomes narrow, resulting in a narrow measurable field of view.

[0016] Therefore, in the stereo camera device of the embodiment, a stereo camera device is configured using a pair of wide-angle camera devices with a short focal length. Then, for monitoring nearby objects in the vicinity of the vehicle during low-speed driving, the distance measurement accuracy is maintained by distance measurement using the stereo camera device. On the other hand, for monitoring distant objects, such as objects more than 50 m ahead of the vehicle, which are required when the distance measurement accuracy becomes insufficient, for example, when the vehicle is traveling at a relatively high speed, distance measurement is performed monocularly using one of the cameras of the stereo camera device. Thereby, it is possible to monitor from a wide-angle short distance to a long distance without increasing the size of the stereo camera device.

[0017] (Hardware Configuration of Stereo Camera Device) FIG. 2 is a block diagram showing the hardware configuration of the stereo camera device in a state where it is provided on a vehicle. In FIG. 2, the stereo camera device 100 includes a left camera device C0, a right camera device C1, and a camera control unit 11 that controls the exposure and imaging timing of each of the camera devices C0 and C1. The stereo camera device 100 also includes frame memories 45 and 46 that store the left and right captured images subjected to A / D conversion processing in frame units, respectively, and an image processing unit 12 that performs predetermined arithmetic processing on the captured images read out for each frame.

[0018] The image processing unit 12 is connected to a correction parameter storage unit 13 and a monocular distance measurement unit 14 that calculates distance information using imaging data from a reference left camera device C0. As the correction parameter storage unit 13, for example, a non-volatile memory can be used. The correction parameter storage unit 13 stores correction parameters for correcting distortion (aberration) generated in each camera device C0, C1. These correction parameters are correction parameters for correcting distortion using polynomial approximation. These correction parameters are generated based on the inspection results obtained by inspecting the distortion in each of the left camera C0 and the right camera C1, as well as the distortion in the entire optical system including the front windshield 70 added during vehicle installation, by referring to the captured images of the measurement pattern during manufacturing or the like.

[0019] Based on the correction parameters stored in the correction parameter storage unit 13, the image processing unit 12 performs distortion correction processing according to the telephoto region and the wide-angle region on each piece of imaging data captured by the left camera device C0 and the right camera device C1.

[0020] For the imaging data of the telephoto region captured by the reference left camera C0, the monocular distance measurement unit 14 estimates the distance from the difference in the movement of feature points on the image by optical flow and calculates the distance information of the telephoto region. This distance information of the telephoto region is transmitted to the digital image processing module 200 via the interface unit 15 and the in-vehicle network (CAN: Controller Area Network), together with the imaging data of each camera device C0, C1.

[0021] The digital image processing module 200 acquires the distance information of the telephoto region and the imaging data of each camera device C0, C1 transmitted from the stereo camera device 100 via the interface unit 47. The deviation detection unit 16 detects the positional deviation of the imaging data of the right camera C1 with respect to the imaging data of the left camera C0 and supplies the detection result to the disparity calculation unit 17.

[0022] Further, the deviation detection unit 16 detects fluctuations in distortion (aberration) due to environmental temperature and aging based on each imaging data, and executes calibration processing to update the correction parameters in the correction parameter storage unit 13.

[0023] The deviation detection unit 16 sequentially shifts the wide-angle region image captured by the right camera C1 serving as a reference image with respect to the imaging data of the wide-angle region captured by the left camera C0 serving as a reference image, and superimposes it on the reference image. The disparity calculation unit 17 obtains the amount of deviation (disparity) when both match. By repeatedly executing this process for each pixel or minute region, disparity image data for the wide-angle region is generated. The processing by the correction parameter storage unit 13 and the deviation detection unit 16 as described above is called, for example, stereo matching processing.

[0024] The distance image generation unit 18 replaces a part of the distance information of the wide-angle region output by the disparity calculation unit 17 with the distance information of the telephoto region output by the image processing unit 12, and outputs distance image data for the entire angle-of-view region. As shown in FIG. 3, for example, in the entire angle-of-view of 120 degrees × 40 degrees, the angle-of-view region 90 of 40 degrees × 10 degrees indicated by the central dotted square corresponding to the telephoto field of view calculates distance information using only the imaging data of the left camera device C0. Further, stereo matching processing with a high calculation load is performed only for the wide-angle region corresponding to the surrounding near-field of view to calculate distance information. The distance information (distance image data) generated in this way is sent to the recognition processing unit 19.

[0025] Thereby, the resolution for distinguishing between a human and an object can be ensured. Further, inconveniences such as an increase in the number of pixels to be processed in the telephoto region and an increase in the calculation load, which occur due to setting a uniform number of pixels over the entire detection region, such as matching the resolution of the wide-angle region, can be prevented.

[0026] Next, based on the distance information, the image recognition processing unit 19 recognizes the three-dimensional shapes of, for example, the vehicle ahead, pedestrians, obstacles, etc., adds color information, and transmits it to the vehicle's ECU (Electronic Control Unit). Based on the recognition result of the image recognition processing unit 19, the vehicle's ECU performs driving support control such as controlling the sounding of an alarm or braking the vehicle via a brake actuator to prevent collisions or adjust the inter-vehicle distance.

[0027] (Appearance and internal configuration of the stereo camera device) Next, FIG. 4 is an exploded perspective view of the stereo camera device 100. FIG. 5 is an exploded perspective view of the main part of the stereo camera device 100 as viewed obliquely from the rear side. FIG. 6 is a cross-sectional view of the stereo camera device 100 cut longitudinally from the position where the lens is provided.

[0028] As shown in FIGS. 4 to 6, the left and right camera devices C0 and C1 each include lens units 21 and 22 having the same optical characteristics, and printed circuit boards 25 and 26 on which image sensors 23 and 24 (an example of an imaging device and a heat dissipation object) are mounted. The printed circuit boards 25 and 26 are an example of a second printed circuit board. As the image sensors 23 and 24, for example, a CMOS (Complementary Metal Oxide Semiconductor) image sensor or a CCD (Charge Coupled Device) image sensor can be used. The left and right camera devices C0 and C1 are integrally supported by an upper cover 20 formed of a heat-resistant member such as an aluminum die-cast or an iron member that constitutes the camera housing.

[0029] On the inner surface side of the upper cover 20, the printed circuit boards 25 and 26 provided with the image sensors 23 and 24 and the printed circuit board 41 provided with the image processing unit 12 are housed. accommodateIt is the portion 48. The lower cover 78 is formed in an L shape by an aluminum die-cast, an iron member, a plastic member, or the like. The lower cover 78 covers the opening on the lower side of the upper cover 20 and engages with the upper cover 20 in such a way as to cover the opening on the rear side of the upper cover 20, and is fixed to the upper cover 20 with screws 52. At this time, the printed circuit board 41 is sandwiched between the upper cover 20 and the lower cover 78 and fastened together with the screws 52. Thereby, the printed circuit board 41 is electrically grounded through the outer edge portion of the printed circuit board 41. Note that the printed circuit board 41 is an example of a first printed circuit board. Also, the upper cover 20 is an example of a first housing member, and the lower cover 78 is an example of a second housing member. And the upper cover 20 and the lower cover 78 constitute a camera housing.

[0030] Also, the stereo camera device 100 is cable-connected to the CAN by a connector terminal 42 provided on the printed circuit board 41. Thereby, the stereo camera device 100 is connected to a digital image processing module 200 incorporated in a part of the vehicle's ECU via the CAN.

[0031] Also, the connector terminal 42 corresponds to the above-described interface portion 15. The connector terminal 42 is provided on the printed circuit board 41 so that the front surface portion (the surface portion on the subject side), the upper surface portion, and both side surface portions are covered by a partition wall 43 formed on the upper cover 20. In other words, the partition wall 43 covers the surface portions of the exposed surface of the connector terminal 42 other than the rear surface portion provided with the terminal to which the cable is connected. As a result, the physical area where the connector terminal 42 is provided and the housing portion 48 of the upper cover 20 are partitioned by the partition wall 43, so that dust or moisture does not enter the housing portion 48 from the gap around the connector terminal 42, and a short circuit of the electric circuit can be avoided. accommodate The inconvenience that dust or moisture enters the housing portion 48 can be prevented, and a short circuit of the electric circuit can be avoided.

[0032] Note that the printed circuit boards 25, 26 and the printed circuit board 41 are arranged such that each board surface is orthogonal so as not to obstruct the driver's view along the angle of the front windshield 70 of the vehicle. Also, the cables (FPC: Flexible Printed Circuits) connecting the printed circuit boards 25, 26 and the printed circuit board 41 are folded inward and stored accommodate in the storage accommodate part 48. Thereby, radiated noise can be shielded.

[0033] Next, the two lens units 21, 22 are screwed into the fitting holes 27, 28 provided in the upper cover 20. Thereby, the lens units 21, 22 are fixed such that their respective optical axes are parallel. Note that the lens units 21, 22 and the respective fitting holes 27, 28 form a lens barrel.

[0034] The printed circuit boards 25, 26 provided with the image sensors 23, 24 are alignment-adjusted with respect to the six axes of the position in the optical axis direction (z direction) and the xy plane orthogonal to the optical axis, and the tilting components αβγ around each of the x, y, and z axes so as to exhibit appropriate imaging characteristics with respect to the lens units 21, 22 fixed to the upper cover 20.

[0035] (Adhesion between the lens barrel and the printed circuit board of the image sensor) Here, on the rear surface portion 49 of the upper cover 20, a first attachment surface portion 31 having a "square-shaped" surface portion to which the printed circuit board 25 is adhered and a first attachment surface portion 32 having a "square-shaped" surface portion to which the printed circuit board 26 is adhered are provided. The printed circuit boards 25, 26 provided with the image sensors 23, 24 are adhered to the first attachment surface portions 31, 32.

[0036] In addition, on the rear surface portion 49 of the upper cover 20, a pair of second attachment surface portions 33 are provided so as to protrude from the outer sides near the approximate centers of the left and right side surface portions of the first attachment surface portion 31 and be located on the same plane as the first attachment surface portion 31. Similarly, on the rear surface portion 49 of the upper cover 20, a pair of second attachment surface portions 34 are provided so as to protrude from the outer sides near the approximate centers of the left and right side surface portions of the first attachment surface portion 32 and be located on the same plane as the first attachment surface portion 32. In other words, the pair of second attachment surface portions 33 and 34 are provided at positions separated by a predetermined distance from the outer peripheral portions of the first attachment surface portions 31 and 32 in the opposite direction of the image sensors 23 and 24.

[0037] FIG. 7 is a cross-sectional view showing only the cross-section of the peripheral portion of the printed circuit board 25 among the cross-sections obtained by cutting the stereo camera device 100 along the x-axis direction from the vicinity of the center of the printed circuit board 25. In this FIG. 7, the pair of protruding portions protruding inward are the first attachment surface portions 31 having a "C-shaped" surface portion to which the printed circuit board 25 is adhered. The pair of second attachment surface portions 33 are provided at positions separated from the first attachment surface portion 31 by a predetermined distance respectively. In other words, a groove portion 55 is formed between the first attachment surface portion 31 and the pair of second attachment surface portions 33. Thereby, the first attachment surface portion 31 and the pair of second attachment surface portions 33 are separated by a predetermined distance. Note that the positional relationship of the second attachment surface portion 34 with respect to the first attachment surface portion 32 having a "C-shaped" surface portion to which the printed circuit board 26 is adhered is also the same positional relationship.

[0038] An ultraviolet curable adhesive (UV curable adhesive) 53 is loaded between the second attachment surface portion 33 shown in FIG. 7 and the printed circuit board 25, and between the second attachment surface portion 34 and the printed circuit board 26. Then, while maintaining the positions and postures of the printed circuit boards 25 and 26 alignment-adjusted as described above, UV light is irradiated onto the UV curable adhesive 53 to cure the UV curable adhesive 53.

[0039] As a result, the printed circuit boards 25 and 26 in a state where the alignment-adjusted positions are maintained are temporarily fixed to the second attachment surfaces 33 and 34 via the UV curable adhesive 53. In other words, both ends of the printed circuit boards 25 and 26 are temporarily fixed to the second attachment surfaces 33 and 34 while maintaining the arrangement of the imaging surfaces of the image sensors 23 and 24 with respect to the lens units 21 and 22.

[0040] FIG. 8 is a diagram showing the adhesion positions of the adhesive with respect to the printed circuit board 25 side among the printed circuit boards 25 and 26. As can be seen from this FIG. 8, the UV curable adhesive 53 applied to the second attachment surface 33 adheres to the vicinity of both the left and right ends of the printed circuit board 25 and is UV cured, whereby the printed circuit board 25 is temporarily fixed to the second attachment surface 33. Note that the printed circuit board 26 is also temporarily fixed to the second attachment surface 34 in the same manner. Also, although it is an example, as the UV curable adhesive 53, a UV curable adhesive 53 mainly composed of an acrylic resin or a urethane resin having a low Young's modulus can be used.

[0041] Note that in this example, it is an example in which the UV curable adhesive 53 applied to the second attachment surfaces 33 and 34 is irradiated with UV light and UV cured. However, a thermosetting adhesive 50 may be applied to the second attachment surfaces 33 and 34 and thermally cured by, for example, irradiating with high-energy laser light or injecting hot air through a nozzle. As a result, the thermosetting adhesive 50 can be used instead of the UV curable adhesive 53 as the temporary fixing adhesive.

[0042] On one side, a thermosetting adhesive 50 mainly composed of an epoxy resin having a high glass transition temperature, for example, is pre-applied to the first mounting surfaces 31 and 32 on the "square bracket-shaped" surface. Therefore, when the printed circuit board 25 is temporarily fixed to the second mounting surface 33 with the UV curable adhesive 53, the thermosetting adhesive 50 adheres to the printed circuit board 25 so as to surround the image sensor 23 as shown in FIG. 8. Similarly, on the printed circuit board 26 side, the thermosetting adhesive 50 adheres to the printed circuit board 25 so as to surround the image sensor 24. In this state, when the stereo camera device 100 is put into a heating furnace, the thermosetting adhesive 50 is thermoset (permanently fixed). As a result, the stereo camera device 100 capable of maintaining the adhesive strength even in a temperature environment of -40°C to 80°C required for in-vehicle use can be manufactured.

[0043] As described above, the upper cover 20 includes first mounting surfaces 31 and 32 formed in a bank shape so as to surround the peripheries of the image sensors 23 and 24. Further, the upper cover 20 includes second mounting surfaces 33 and 34 for temporarily fixing the outer edges of the printed circuit boards 25 and 26 at a plurality of locations outside the first mounting surfaces 31 and 32.

[0044] The thermosetting adhesive 50 is applied to the first mounting surfaces 31 and 32, and the UV curable adhesive 53 is applied to the second mounting surfaces 33 and 34. The second mounting surfaces 33 and 34 are formed at positions symmetric with respect to the central axis of the image sensors 23 and 24.

[0045] In other words, the second mounting surfaces 33 and 34 are provided at positions symmetric with respect to the y-axis of the image sensors 23 and 24 so that the tensile forces at the adhesion points of the printed circuit boards 25 and 26 are balanced in the parallel direction of the camera devices C0 and C1, which is the direction having a large influence on the parallax calculation accuracy. The direction of the x-axis (left-right axis) is the direction in which the camera devices C0 and C1 are arranged in parallel, and the direction of the y-axis is the direction orthogonal to the x-axis (left-right axis) on a two-dimensional plane. Thereby, it is possible to prevent the inconvenience that the accuracy of the parallax calculation is reduced due to the deviation of the parallelism of the optical axes between the camera devices C0 and C1.

[0046] Also, the UV-curable adhesive 53 does not apply a biased tensile force due to curing shrinkage to the printed circuit boards 25 and 26. Therefore, the printed circuit boards 25 and 26 can be fixed to the upper cover 20 while maintaining the positions of the alignment-adjusted image sensors 23 and 24.

[0047] That is, the stereo camera device 100 of the embodiment uses, as the UV-curable adhesive 53, an adhesive mainly composed of an acrylic resin or a urethane resin that is resistant to impact and tension and has high flexibility. On the other hand, for the thermosetting adhesive 50, an adhesive mainly composed of an epoxy resin with high heat resistance and being hard and tough is used. The thermosetting adhesive 50 and the UV-curable adhesive 53 are applied at separated positions as the first attachment surfaces 31 and 32 and the second attachment surfaces 33 and 34, respectively, as shown in FIGS. 5 and 7 and the like. And the highly flexible UV-curable adhesive 53 is disposed on the outer second attachment surfaces 33 and 34. Thereby, it is possible to prevent the inconvenience that the printed circuit boards 25 and 26 are peeled off from the upper cover 20 due to the shear stress caused by the difference in thermal expansion and contraction between the upper cover 20 and the printed circuit boards 25 and 26.

[0048] More specifically, the stereo camera device 100 of the embodiment selects, as the thermosetting adhesive 50, an adhesive having physical properties such that the intermolecular cohesive force, that is, the Young's modulus (elastic modulus), is equal to or higher than that of the UV-curable adhesive 53. Note that the main agents of the UV-curable adhesive 53 and the thermosetting adhesive 50 may be the same. For example, by aligning the physical properties with an epoxy resin as the main agent and selecting a curing accelerator to be blended, the UV-curable type or the thermosetting type may be properly used according to the requirements of the process design.

[0049] By using the UV-curable adhesive 53, the upper cover 20 and the printed circuit boards 25, 26 can be fixed in a short time while maintaining each part after alignment adjustment. Further, by thermally curing the thermosetting adhesive 50 in this state, the thermosetting adhesive 50 can be thermally cured while maintaining each part after alignment adjustment with the UV-curable adhesive 53, and the upper cover 20 and the printed circuit boards 25, 26 can be fixed. Therefore, even when the first attachment surfaces 31, 32 are formed in a deep part where UV light hardly reaches, due to the second attachment surfaces 33, 34 and temporary fixing with the UV-curable adhesive 53, the printed circuit boards 25, 26 can be firmly fixed to the upper cover 20 by thermal curing of the thermosetting adhesive 50 while maintaining the adjusted alignment. Also, the gaps between the first attachment surfaces 31, 32 and the printed circuit boards 25, 26 can be sealed so as to surround the periphery of the image sensors 23, 24 with the thermosetting adhesive 50. For this reason, it is possible to prevent the inconvenience that dust, water droplets, etc. enter from the gaps between the first attachment surfaces 31, 32 and the printed circuit boards 25, 26.

[0050] Note that, as the adhesive for this fixing, instead of the thermosetting adhesive 50, a moisture-curable adhesive that cures with moisture in the air or the like may be used. Alternatively, the thermosetting adhesive 50 and the moisture-curable adhesive may be used in combination.

[0051] (Structure for Suppressing Change in Imaging Characteristics due to Temperature Change) Next, a structure for suppressing a change in imaging characteristics due to a temperature change of the stereo camera device 100 according to the embodiment will be described. In the case of the stereo camera device 100 according to the embodiment, in order to achieve a wide-angle view, as shown in FIG. 6, as the lens units 21, 22, a so-called retrofocus lens (inverted telephoto lens) formed by housing a front concave lens and a rear convex lens with their optical axes aligned in a lens cell 60 is used. On the outer periphery of the lens cell 60, a fitting portion 62 for positioning the optical axis, a screwing portion 63 for tightening with a predetermined axial force in the optical axis direction, and a locking portion 64 are formed.

[0052] Generally, a wide-angle lens has a short focal length, and the principal point position 65 of the optical system, indicated by "×" in Fig. 6, is biased toward the image sensor 23 side. Therefore, even with such an arrangement, a holding structure is desired that does not cause fluctuations in the principal point position 65 due to lens displacement and posture changes within the fitting holes 27 and 28.

[0053] Therefore, in the case of the stereo camera device 100 of the embodiment, the fitting portion 62 provided near the end portion of the lens cell 60 on the image sensor 23 side maintains at least the position of the principal point position 65 of the optical system and the parallelism of the optical axis.

[0054] The screwing portion 63 is provided on the subject side (near the end portion of the lens cell 60 on the side opposite to the image sensor 23) with respect to the fitting portion 62 of the lens cell 60. The locking portion 64 is provided further on the subject side than the screwing portion 63. The locking portion 64 abuts against the lens units 21 and 22 screwed into the respective fitting holes 27 and 28 with a predetermined axial force. Thereby, the centers of the respective image sensors 23 and 24 and the optical axes of the lens units 21 and 22 are positioned to coincide. In this way, by screwing the lens units 21 and 22 into the respective fitting holes 27 and 28, an axial force that can withstand thermal expansion and contraction due to temperature changes, creep (increase in distortion) due to aging deterioration, vibration, or impact can be maintained.

[0055] Also, when the temperature rises, due to thermal expansion, the portion screwed into the screwing portion 63 of the lens units 21 and 22 moves in a direction away from the image sensors 23 and 24. On the other hand, the portion fitted into the fitting portion 62 of the lens units 21 and 22 moves so as to approach the image sensors 23 and 24. For this reason, when the lens units 21 and 22 thermally expand, the principal point position 65 moves so as to approach the image sensors 23 and 24. Therefore, the distance variation between the principal point position 65 and the image sensors 23 and 24 can be reduced, and the change in imaging characteristics due to temperature changes can be suppressed.

[0056] The retrofocus lens is divided into a front group and a rear group with a diaphragm in between. The light beam diameter becomes smaller as it gets closer to the diaphragm, and since the lens aperture is small, each lens is inserted in such a way that it abuts against the back from the front and rear openings of the lens cell 60 in order of decreasing aperture, and a predetermined axial force is applied by screwing a retaining ring onto the open end.

[0057] For each lens, the outer peripheral part of each lens is fitted into the fitting hole in the lens cell 60, so that the axis center is positioned, and positioning in the optical axis direction is performed with a spacer ring sandwiched between the lenses. That is, the circumferential position of the spacer ring is maintained by the pressure contact force in the optical axis direction received from the front and rear lenses to be sandwiched. However, depending on the circumferential position of the spacer ring, when the inner diameter of the fitting hole of the lens cell 60 shrinks at low temperature, an external force may be applied in the circumferential direction and distortion may occur. As a result, due to the restoring force when the temperature rises, the lens axis center shifts within the clearance of the fitting hole in the lens cell 60, causing the inconvenience that the distortion fluctuates.

[0058] FIG. 9 is a cross-sectional view of the main part in a state where the lens units 21 and 22 are screwed into the respective fitting holes 27 and 28 of the upper cover 20 and the upper cover 20 is cut along the optical axis. As shown in this FIG. 9, in the case of the stereo camera device 100 of the embodiment, the circumferential positioning of the spacer ring 80 is performed by adjusting the spacer ring 80 and assembling it, and then tightening the retaining ring 85 to apply an axial force. Thereby, even when the inner diameter of the fitting hole in the lens cell 60 shrinks at low temperature, a clearance 82 can be secured so that the lenses do not contact each other.

[0059] Here, there is a limit to the accuracy of the parallelism of the camera devices C0 and C1, and a relative error occurs due to a slight misalignment of each camera device C0 and C1. FIG. 10 is a diagram showing the types of relative errors of each camera device C0 and C1. FIG. 10(a) shows a rotational misalignment in the horizontal direction, and FIG. 10(b) shows a translational misalignment in the vertical direction. Also, FIG. 10(c) shows a rotational misalignment in the vertical direction, and FIG. 10(d) shows a rotational misalignment around the optical axis.

[0060] As described above, each of the camera devices C0 and C1 has the relative errors illustrated in FIGS. 10(a) to 10(c). Further, when mounted on a vehicle, optical errors also occur due to the undulation of the front windshield 70 or the like. Therefore, when performing a parallax calculation based on the difference between the captured images of the left and right camera devices C0 and C1, if the deviation between the images of the camera devices C0 and C1 remaining as a correction error after complicated distortion correction exceeds the allowable value, it becomes difficult to maintain the distance measurement accuracy.

[0061] Further, even though the amount of information processing tends to increase as the number of pixels of the image sensors 23 and 24 increases, it is desirable to minimize the influence of heat generation by the image sensors 23 and 24 and the image processing circuit.

[0062] Therefore, the stereo camera device 100 according to the embodiment is provided with an image processing unit 12 for correcting the distortion with a single eye for the captured images (luminance images) of the camera devices C0 and C1, respectively, inside the stereo camera device 100. On the other hand, a parallax calculation unit 17 that executes a parallax calculation with both eyes is provided on the side of a digital image processing module 200 provided outside the stereo camera device 100. By physically separating the parallax calculation function such as the parallax calculation unit 17 from the stereo camera device 100, the calculation load of the image processing unit 12 can be reduced, the temperature rise inside the upper cover 20 can be suppressed, and the displacement of the lens units 21 and 22 can be prevented.

[0063] (Heat dissipation structure) Next, the heat dissipation structure of the stereo camera device 100 according to the embodiment will be described. The stereo camera device 100 according to the embodiment is configured to transfer the heat generated in the printed circuit board 41 on which the LSI (Large Scale Integration) element or FPGA (Field-Programmable Gate Array) of the image processing unit 12 (an example of an object to be heat-dissipated) is provided, mainly to the lower cover 78 for heat dissipation. Similarly, the stereo camera device 100 according to the embodiment is also configured to transfer the heat generated in the printed circuit boards 25 and 26 on which the image sensors 23 and 24 are provided, mainly to the lower cover 78 for heat dissipation. Note that the upper cover 20 and the lower cover 78 constitute the housing of the stereo camera device 100.

[0064] Specifically, as shown in FIG. 4, the lower cover 78 is provided with convex pedestal surfaces 75, 76, and 77 formed by drawing at positions facing the back surfaces of the printed circuit board 41 and the printed circuit boards 25 and 26. The pedestal surface 75 and the pedestal surface 76 are examples of the second heat transfer part. The pedestal surface 77 is an example of the first heat transfer part.

[0065] A heat dissipation grease 51 (an example of a heat conductive material) is applied to each of the pedestal surfaces 75, 76, and 77. When the lower cover 78 is fitted into the upper cover 20 in this state, the heat dissipation grease 51 crushed by the pedestal surfaces 75, 76, 77 and the printed circuit boards 25, 26, and 41 spreads into the gaps between the pedestal surfaces 75, 76, 77 and the printed circuit boards 25, 26, and 41. As a result, each of the pedestal surfaces 75, 76, 77 and the printed circuit board 41 can be brought into contact with each other via the heat dissipation grease 51, and the adhesion between the two can be improved. In addition, since the heat dissipation grease 51 functions as a heat transfer circuit so to speak, the heat generated in the printed circuit boards 25, 26, and 41 can be transferred to the lower cover 78, which is a cooling member, for heat dissipation.

[0066] As the heat-dissipating grease 51, for example, a paste-like resin in which a powder with good thermal conductivity such as aluminum oxide (alumina) is blended in silicone oil can be used. Further, the spreading area of the heat-dissipating grease 51 spread by being crushed by each pedestal surface portion 75, 76, 77 and the printed circuit boards 25, 26, 41 is determined based on the heat generation amount (power consumption) of the LSI element or FPGA that integrates the image sensors 23, 24 and the image processing unit 12, etc. which are heat sources, and the thermal resistance of the heat-dissipating grease 51.

[0067] Further, since the printed circuit boards 25, 26 serve as upright walls (because the stereo camera device 100 becomes perpendicular to the ground when installed in a vehicle), at least the heat-dissipating grease 51 applied to the pedestal surface portions 75, 76 is a curable heat-dissipating grease 51 so as not to flow down onto the pedestal surface portions 75, 76.

[0068] By using such a paste-like heat-dissipating grease 51, when the upper cover 20 and the lower cover 78 are fitted together, it is possible to prevent the inconvenience that a load is applied to the printed circuit boards 25, 26, 41 by being pressed at each pedestal surface portion 75, 76, 77. Note that, instead of the heat-dissipating grease 51, for example, a sheet-like silicone pad or the like may be used. In this case as well, the same effect can be obtained.

[0069] Further, it is also desirable from the viewpoint of efficient heat dissipation that the pedestal surface portions 75, 76, 77 be positioned to face the portions close to the heat source (with high temperature). For this reason, the pedestal surface portions 75, 76 are provided on the lower cover 78 so as to face the back surfaces of the printed circuit boards 25, 26 corresponding to the mounting portions of the image sensors 23, 24, and the pedestal surface portion 77 is provided on the lower cover 78 so as to face the package surface of the LSI element or FPGA such as the image processing unit 12 mounted on the printed circuit board 41. Thereby, efficient heat dissipation is made possible.

[0070] Further, the outer air side surface of the lower cover 78 is subjected to a surface treatment with a black paint applied thereon, and / or the outer air side surface of the lower cover 78 is subjected to a surface treatment that forms unevenness overall to increase the surface area. Thereby, the heat generated in the image sensors 23, 24, the image processing unit 12, etc., which is transmitted to the lower cover 78 via the heat dissipation grease 51 and the pedestal surfaces 75, 76, 77, can be efficiently dissipated via the lower cover 78.

[0071] Also, as shown in FIG. 4, on the upper cover 20, heat dissipation fins 29 are provided between the fitting holes 27, 28 that fit with the lens units 21, 22. Thereby, the surface area of the upper cover 20 can be increased, and the heat dissipation effect in the vicinity of the fitting holes 27, 28 of the lens units 21, 22 can be enhanced.

[0072] Also, even if the amount of information processing of the image processing unit 12 increases and the amount of heat generation increases by increasing the number of pixels of the image sensors 23, 24, heat can be efficiently dissipated via the upper cover 20 and the lower cover 78. For this reason, displacement of the lenses of the lens units 21, 22 due to heat generation can be prevented, and the imaging accuracy can be maintained.

[0073] (Calibration Processing) Next, the calibration processing in the stereo camera device 100 will be described. In the stereo camera device 100 of the embodiment, a parallax calculation unit 17 is provided in a digital image processing module 200 that is physically different from the stereo camera device 100. In order to execute parallax calculation, it is necessary to sequentially shift the reference image captured by the left camera device C0 and overlap it with the reference image while overlapping it with the reference image captured by the right camera device C1.

[0074] The deviation detection unit 16 shown in FIG. 2 detects the horizontal position deviation dx and the vertical position deviation dy of the captured image for each frame based on the images (luminance images) captured by the two camera devices C0 and C1. The parallax calculation unit 17 corrects the image position by moving the captured image in the horizontal and vertical directions using, for example, an affine transformation or the like based on the horizontal position deviation dx and the vertical position deviation dy detected by the deviation detection unit 16. Then, the parallax calculation unit 17 performs a parallax calculation process based on each captured image whose image position has been corrected in this way.

[0075] Note that the camera control unit 11 of the stereo camera device 100 shown in FIG. 2 controls the imaging timing of either one of the two camera devices C0 and C1 according to the position deviation detected by the deviation detection unit 16.

[0076] Here, in order to improve the parallax calculation accuracy in the parallax calculation unit 17, in addition to the position deviation (dx, dy) of the captured image for each frame detected by the deviation detection unit 12, it is also necessary to correct the distortion (distortion aberration) caused by the optical system errors of the camera devices C0 and C1 and the shape error of the front windshield 70.

[0077] Each lens unit 21, 22 provided in the left and right camera devices C0, C1 has a small distortion in the telephoto region, but a large distortion in the wide-angle region. The correction parameter storage unit 13 shown in FIG. 2 stores correction parameters optimized according to the initial (at the time of assembly) distortion characteristics.

[0078] The image processing unit 12 performs a geometric correction that gradually increases the distortion correction amount in accordance with the increase amount of the distortion in the wide-angle region. Thereby, a distortion correction processed image in the telephoto region and a distortion correction processed image in the wide-angle region are created.

[0079] In addition, for the positional deviation or attitude change of the lens that occurs linearly such as temperature fluctuation, the deviation detection unit 16 measures the distortion generated in the captured image in advance and performs polynomial approximation processing, thereby calculating correction parameters capable of reproducing an ideal original image with the lens units 21 and 22, and setting them in the correction parameter storage unit 13.

[0080] However, the initial positions of the lens units 21 and 22 change over time due to the influence of vehicle vibration or environmental changes. Therefore, it becomes difficult over time to accurately correct the distortion generated in the captured image with the correction parameters generated based on the tendency of the distortion change of the linearly assumed captured image.

[0081] For this reason, at the timing when a predetermined time has elapsed, secondary correction is required to detect the tendency of the distortion direction of the captured image based on the feature points of the captured image and correct the distortion of the captured image. However, the positional deviation or attitude change of the lens units 21 and 22 often occurs in a complex entanglement of changes in the x-axis, y-axis, z-axis, α-axis, β-axis, and γ-axis.

[0082] Therefore, the deviation detection unit 16 associates the tendency of the distortion direction of the captured image with the changes in the x-axis, y-axis, z-axis, α-axis, β-axis, and γ-axis by using, for example, deep learning, and analyzes the combination of the fluctuations of the axes that caused the change in distortion. Then, based on the analysis result, the deviation detection unit 16 updates the correction parameters in the correction parameter storage unit 13 at a predetermined timing.

[0083] As a result, calibration processing corresponding to the positional deviation or attitude change of the lens units 21 and 22 in the x-axis, y-axis, z-axis, α-axis, β-axis, and γ-axis can be executed, and an ideal original image can be reproduced without being affected by the passage of time.

[0084] In this way, in addition to detecting the positional deviation and rotational deviation of the captured images of the camera devices C0 and C1, the deviation detection unit 16 detects the difference in the distortion pattern of each captured image after the distortion correction process, ensuring the correction accuracy in the image processing unit 12.

[0085] FIG. 11 is a flowchart showing the flow of the calibration process of the deviation detection unit 16 for updating the correction parameters stored in the correction parameter storage unit 13. The deviation detection unit 16 executes the calibration process shown in the flowchart of FIG. 11 for one frame of stereo images (reference image, reference image).

[0086] In the flowchart of FIG. 11, first, in step S1, the image processing unit 12 acquires one frame of reference image and reference image captured simultaneously by two camera devices C0 and C1 arranged in parallel. In step S2, the image processing unit 12 performs distortion correction processing on the correction parameters currently stored in the correction parameter storage unit 13.

[0087] Next, in step S3, the deviation detection unit 16 extracts a plurality of feature points in the reference image. Also, in step S4, the deviation detection unit 16 executes a corresponding point search for searching for an image with high correlation with the image around the feature points extracted from the reference image from the reference image. In other words, the deviation detection unit 16 executes a corresponding point search for searching for the feature points on the reference image corresponding to the feature points extracted from the reference image.

[0088] Specifically, assuming that the left and right camera devices C0 and C1 are parallel and at the same level, the deviation detection unit 16 searches for corresponding points in the vertical and horizontal directions, and obtains the corresponding position differences (dx, dy) in the vertical and horizontal two-dimensional directions for each of the plurality of feature points in the reference image. Thereby, the deviation detection unit 16 obtains, for each of the plurality of feature points in the reference image, the horizontal component dx and the vertical component dy of the parallax indicating the difference between the position of the feature point on the reference image and the position of the feature point on the reference image, and the horizontal component xi and the vertical component yi of the image position of the feature point on the reference image, and obtains corresponding points including these.

[0089] Next, in step S5, the deviation detection unit 16 determines whether the number of corresponding points found exceeds a threshold value. If the number of corresponding points found exceeds the threshold value (step S5: Yes), in step S6, the deviation detection unit 16 determines whether the deviation amount between the corresponding points on the reference image and a plurality of feature points on the reference image exceeds an allowable value. If the deviation amount between the corresponding points on the reference image and a plurality of feature points on the reference image does not exceed the allowable value (step S6: Yes), the process proceeds to step S7. Then, in this step S7, the disparity calculation unit 17 performs disparity calculation on the reference image and the reference image.

[0090] On the other hand, if it is determined in step S5 that the number of corresponding points is less than the threshold value (step S5: No), and if the deviation amount between the corresponding points on the reference image and a plurality of feature points on the reference image does not exceed the allowable value (step S6: No), the process proceeds to step S8. In step S8, the deviation detection unit 16 identifies the deviation factors of the lens units 21 and 22 that increase the distortion by pattern recognition of the distortion method learned in advance. Then, based on the identification result of the deviation factor, the deviation detection unit 16 updates the correction parameters stored in the correction parameter storage unit 13 (step S9).

[0091] By repeatedly executing the processes of steps S1 to S6 and steps S8 to S9 in this way, the distortion can be gradually improved and brought closer to the original image. Also, by performing predetermined image processing (correction processing) separately for the telephoto region and the wide-angle region, the identification accuracy in the wide-angle region can be ensured, the distance measurement accuracy in the telephoto region can be ensured, and the accuracy degradation due to temperature fluctuations and temporal fluctuations can be minimized.

[0092] (Effect of the Embodiment) As is clear from the above description, in the stereo camera device 100 of the embodiment, convex pedestal surfaces 75, 76, and 77 are provided on the lower cover 78 at positions facing the back surfaces of the printed circuit boards 41 and 25, 26. Then, heat dissipation grease 51 is applied to each of the pedestal surfaces 75, 76, and 77. The lower cover 78 is fitted into the upper cover 20. As a result, the heat dissipation grease 51 crushed by the pedestal surfaces 75, 76, 77 and the printed circuit boards 25, 26, 41 spreads into the gaps between the pedestal surfaces 75, 76, 77 and the printed circuit boards 25, 26, 41, and the two are in close contact with each other via the heat dissipation grease 51. Thus, the heat dissipation grease 51 functions as a so-called heat transfer circuit, and the heat generated in the printed circuit boards 25, 26, 41 can be transferred to the lower cover 78, which is a cooling member, for heat dissipation.

[0093] Further, the stereo camera device 100 of the embodiment is not structured to directly fasten the printed circuit boards 25, 26 on which the image sensors 23, 24 are provided to the upper cover 20, but is structured to be fixed via adhesives such as a UV curable adhesive 53 and a thermosetting adhesive 50. Since the main material of adhesives such as the UV curable adhesive 53 and the thermosetting adhesive 50 is resin, the thermal resistance is high. Therefore, by adopting a structure in which the printed circuit boards 25, 26 are fixed to the upper cover 20 via an adhesive, it is possible to prevent the inconvenience of heat generated in the printed circuit boards 25, 26 from being transferred to the fitting holes 27, 28 that serve as support portions of the lens units 21, 22 close to the upper cover 20.

[0094] Moreover, since the stereo camera device 100 of the embodiment forms a heat circuit that transfers heat to the lower cover 78 via the heat dissipation grease 51, heat can be efficiently transferred to the lower cover 78 and the upper cover 20 joined to the lower cover 78 for heat dissipation. Therefore, it is possible to avoid an increase in the temperature of the image sensors 23, 24 mounted on the printed circuit boards 25, 26.

[0095] Also, a curable heat dissipation grease 51 is used for the pedestal surfaces 75, 76 with respect to the printed circuit boards 25, 26 that serve as vertical walls. Thereby, it is possible to prevent the inconvenience that the heat dissipation grease 51 flows down from the pedestal surfaces 75, 76 corresponding to the printed circuit boards 25, 26 that serve as vertical walls.

[0096] In addition, since the heat dissipation grease 51 is in paste form, when the upper cover 20 and the lower cover 78 are fitted together, it is possible to prevent the inconvenience that a load is applied to the printed circuit boards 25, 26, 41 by being pressed by the pedestal surfaces 75, 76, 77.

[0097] Further, the pedestal surfaces 75, 76 are provided on the lower cover 78 so as to face the back surfaces of the printed circuit boards 25, 26 corresponding to the mounting portions of the image sensors 23, 24, and the pedestal surface 77 is provided on the lower cover 78 so as to face the package surfaces of LSI elements such as the image processing unit 12 or FPGAs mounted on the printed circuit board 41. Thereby, heat can be dissipated efficiently.

[0098] In addition, the outer air side surface of the lower cover 78 is subjected to a surface treatment in which a black paint is applied, and / or the outer air side surface of the lower cover 78 is subjected to a surface treatment in which unevenness is formed as a whole to increase the surface area. Thereby, the heat generated in the image sensors 23, 24 and the image processing unit 12 etc. and transmitted to the lower cover 78 via the heat dissipation grease 51 and the pedestal surfaces 75, 76, 77 can be efficiently dissipated via the lower cover 78.

[0099] In addition, heat dissipation fins 29 are provided between the fitting holes 27, 28 that fit with the lens units 21, 22 in the upper cover 20. Thereby, the surface area of the upper cover 20 can be increased, and the heat dissipation effect in the vicinity of the fitting holes 27, 28 of the lens units 21, 22 can be enhanced.

[0100] In addition, even if the amount of information processing of the image processing unit 12 increases and the amount of heat generation increases by increasing the number of pixels of the image sensors 23, 24, heat can be efficiently dissipated via the upper cover 20 and the lower cover 78. For this reason, displacement of the lenses of the lens units 21, 22 due to heat generation can be prevented, and the imaging accuracy can be maintained.

[0101] Finally, the above-described embodiments are presented as examples and are not intended to limit the scope of the present invention. This novel embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. Such embodiments and modifications of the embodiments are included in the scope and gist of the invention and are included in the invention described in the claims and the equivalent scope thereof.

Explanation of Reference Numerals

[0102] 11 Camera control unit 12 Image processing unit 13 Correction parameter storage unit 14 Monocular distance measurement unit 15 Interface unit 16 Deviation detection unit 17 Parallax calculation unit 18 Distance image generation unit 19 Image recognition processing unit 20 Upper cover 21 Lens unit 22 Lens unit 23 Image sensor 24 Image sensor 25 Printed circuit board 26 Printed circuit board 27 Fitting hole 28 Fitting hole 29 Heat dissipation fins of the upper cover 31 First mounting surface 32 First mounting surface 33 Second mounting surface 34 Second mounting surface 41 Printed circuit board 42 Connector terminal 43 Partition wall 48 Accommodation part of the upper cover 49 Rear surface part of the upper cover 50 Thermosetting adhesive 51 Heat dissipation grease 52 Screw 53 UV curable adhesive 60 Lens cell 62 Fitting part 63 Screwing part 64 Locking part 65 Main point position 70 Front windshield 75 Base surface part 76 Base surface part 77 Base surface part 78 Lower cover 100 Stereo camera device 200 Digital image processing module C0 Left camera device C1 Right camera device

Prior art documents

Patent documents

[0103]

Patent Document 1

Claims

1. A lens barrel that holds an optical element, An image sensor for acquiring a subject image formed by the optical element, A first printed circuit board having an image processing circuit for an image captured by the image sensor, A second printed circuit board on which the image sensor is mounted, A camera housing that holds the lens barrel, the image sensor, the first printed circuit board, and the second printed circuit board, An imaging device having: The camera housing includes: A first housing member that holds the lens barrel, the image sensor, and the second printed circuit board, A second housing member that seals a housing portion of the first housing member that houses the first printed circuit board and the second printed circuit board, And is provided with: The second housing member includes: A first heat transfer portion that transfers heat generated on the first printed circuit board to the second housing member, A second heat transfer portion that transfers heat generated on the second printed circuit board to the second housing member, And has: The second printed circuit board is fixed to the first housing member via a member having a high thermal resistance so that heat generated on the second printed circuit board mainly moves to the second housing member. An imaging device characterized by the above.

2. The first heat transfer portion includes a first pedestal surface portion that protrudes in the direction of the heat dissipation object of the first printed circuit board, The second heat transfer portion includes a second pedestal surface portion that protrudes in the direction of the heat dissipation object of the second printed circuit board. The imaging device according to claim 1, characterized by the above.

3. The first pedestal surface portion and the second pedestal surface portion are each in contact with the heat dissipation object via a heat conductive material. The imaging device according to claim 2, characterized by the above.

4. The heat conductive material is a paste-like heat conductive grease that is in an uncured state during application. The imaging device according to claim 3, characterized by the above.

5. Among the first printed circuit board and the second printed circuit board, the heat conductive material applied to the first pedestal surface portion or the second pedestal surface portion that contacts the heat dissipation object provided on the printed circuit board that is perpendicular to the ground when the imaging device is installed is A curable heat conductive material. The imaging device according to claim 3 or claim 4, characterized by the above.

6. A lens barrel that holds an optical element, An image sensor for acquiring a subject image formed by the optical element, A first printed circuit board having an image processing circuit for an image captured by the image sensor, A second printed circuit board on which the imaging device is mounted, A camera housing, A method of assembling an imaging device having: The camera housing includes: A first housing member that holds the lens barrel, the imaging device, and the second printed circuit board; A second housing member that seals a housing portion of the first housing member that houses the first printed circuit board and the second printed circuit board; And is provided with: The second printed circuit board is fixed to the first housing member via a member having high thermal resistance so that heat generated in the second printed circuit board mainly moves to the second housing member. The camera housing: Is provided with a second heat transfer portion protruding in the direction of a heat dissipation target provided on the second printed circuit board so as to face the heat dissipation target provided on the second printed circuit board on the second housing member; Is provided with a first heat transfer portion protruding in the direction of a heat dissipation target provided on the first printed circuit board so as to face the heat dissipation target provided on the first printed circuit board on the second housing member; Apply a heat conductive material to the second heat transfer portion and the first heat transfer portion; Assemble so that the second heat transfer portion and the heat dissipation target provided on the second printed circuit board are in contact with each other via the heat conductive material, and the first heat transfer portion and the heat dissipation target provided on the first printed circuit board are in contact with each other via the heat conductive material. A method of assembling an imaging device.

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