Camera module, imaging system, and mobile body

Abstract

Provided are a camera module, an imaging system, and a mobile body capable of suppressing propagation of vibration between housings, ensuring desired vibration performance, and preventing noise.　In the camera module, a vibration propagation limiting means for limiting propagation of vibration is provided in a vibration propagation path through which vibration from a first lens 31 vibrated by a vibration mechanism 60 sequentially propagates to a first housing 23, a second housing 24, and a third housing 25 in this order. The vibration propagation limiting means includes washers 84, 89 interposed between heads 80a, 85a of screws 80, 85 and the housings 24, 25, and includes buffer materials 90, 92 interposed between joint surfaces of the housings 23, 24, 25.

Description

Camera module, imaging system, and mobile object

[0001] The present invention relates to a camera module such as an in-vehicle camera mounted on a vehicle such as an automobile, an imaging system, and a mobile object equipped with an imaging system.

[0002] Conventionally, automobiles have been equipped with on-board cameras to assist with parking and prevent collisions through image recognition, and attempts have also been made to apply such cameras to autonomous driving. In addition, a camera module such as an on-board camera generally includes a lens unit having a lens group formed by a plurality of lenses arranged along an optical axis, a lens barrel that houses and holds the lens group, and an aperture member disposed between at least one of the lenses in the lens group (see, for example, Patent Document 1).

[0003] Furthermore, such lens units may be attached to a mounting portion such as the front grille of a vehicle (automobile), with the lens closest to the object exposed to the outside. In such cases, foreign matter such as water droplets, muddy water, ice, snow, and frost easily adheres to the surface of the lens. If this happens, it is necessary to remove the foreign matter to ensure a clear field of view for observation using the lens unit.

[0004] In recent years, foreign matter adhering to the surface of a lens (or lens cover) has been removed by vibrating the lens (or lens cover) with a vibrating body (ultrasonic vibration). For example, in Patent Document 2, a vibrating device for removing foreign matter such as water droplets and dust adhering to a dome-shaped cover (lens cover) is provided in a camera equipped with a lens unit.

[0005] Specifically, as shown in Figure 8, such a vibration device 102 is provided in a camera that has an imaging unit 105 with a lens 106 and a circuit including an imaging element built in at the top of the camera body 103, and is equipped with a dome-shaped transparent cover 111, a cylindrical vibrating body 112 to which the cover 111 is fixed, and a piezoelectric element 113 that is fixed to the vibrating body 112 and vibrates the cover 111 via the vibrating body 112. The vibrating body 112 has a cylindrical portion 114 having a first end 114a located on the cover 111 side and a second end 114b located on the opposite side from the cover 111, a cylindrical first connecting portion 115 connected to the first end 114a of the cylindrical portion 114 and consisting of a cylinder with an inner diameter larger than that of the cylindrical portion 114, a first ring-shaped portion 116 interposed between the first connecting portion 115 and the cover 111 and having an inner diameter smaller than that of the first connecting portion 115, a second connecting portion 117 connected to the second end 114b of the cylindrical portion 114 and consisting of a cylinder with an outer diameter smaller than that of the cylindrical portion 114, and a second ring-shaped portion 118 interposed between the second connecting portion 117 and the piezoelectric element 113 and having an outer diameter larger than that of the second connecting portion 117.

[0006] In such a vibration device 102, by driving the piezoelectric element 113 and ultrasonically vibrating the cover 111 via the vibrating body 112, the movement and atomization of droplets can be more effectively achieved, or foreign matter adhering to the surface of the cover 111 can be removed.

[0007] JP 2013-231993 A Japanese Patent No. 6977784 A

[0008] Incidentally, all of the components of such a compact camera module, including the camera body 103 and the vibration device 102, are housed within a housing 130. In this case, the housing 130 may be constructed by joining multiple housing parts together for reasons such as ease of assembly of the camera components. In particular, when, for reasons of ease of assembly or design, the housing 130 is constructed from a cylindrical first housing that forms an internal storage space for accommodating the vibration device 102 and the lens unit including the lens 106 and the lens barrel, a substantially thin-walled, dish-shaped second housing that forms a recess that primarily accommodates a board portion on which an imaging element of the image sensor module (imaging module) that constitutes the imaging unit 105 is mounted, and a cylindrical third housing that forms an internal storage space for accommodating most of the image sensor module and part of the extension from the image sensor module, one problem may arise.

[0009] In other words, in the split-casing structure described above, the casings must be joined together, for example, with screws. However, especially when the casings are made of different materials, vibrations of the lens or cover vibrated by the vibration device are transmitted sequentially through the joint surfaces and screws between the casings, from the first casing closest to the object to the second casing and then to the third casing closest to the image. This vibration transmission can degrade vibration energy, reduce vibration performance, and reduce the vibration displacement of the lens or cover, potentially making it impossible to atomize water droplets or the like adhering to the lens or cover. Furthermore, this vibration transmission can also cause noise due to impacts and resonance between the casings.

[0010] FIG. 9 shows experimental data by the inventors, which shows the vibration displacement (unit: μm) of the lens or cover caused by a vibration device provided on a first housing when the housings have a rectangular cross section and are fastened together at their four corners with screws, for different states in which the housings are made of different materials (for example, the first housing is made of stainless steel (SUS304), the second housing is made of engineering plastic (PPS resin), and the third housing is made of aluminum alloy (A5052)). That is, when there is only the first housing (when the second and third housings are not joined), the vibration displacement of the lens or cover is the largest (approximately 35 μm in the figure), but when the second housing is fastened and joined to the image side of the first housing, the vibration displacement of the lens or cover decreases to nearly 30 μm, and when the third housing is further fastened and joined to the image side of the second housing (when the first, second, and third housings are all fastened and joined to each other), the vibration displacement of the lens or cover decreases significantly to approximately 5 μm. Thus, it can be seen that the vibration energy decreases significantly as the housings are successively joined to the image side.

[0011] The present invention has been made in consideration of the above circumstances, and aims to provide a camera module, an imaging system, and a moving body that can suppress the propagation of vibration between housings, ensure desired vibration performance, and prevent noise.

[0012] In order to solve the above problem, the present invention provides a camera module comprising a lens group in which a plurality of lenses are arranged along the optical axes of the lenses, a lens barrel that houses and holds the lens group, and an image sensor that converts light collected through the lens group into an electrical signal, the camera module comprising: a cylindrical first housing that forms an accommodation space inside to receive the lens barrel that houses and holds the lens group; a second housing that is coupled to the image side of the first housing and forms a recess that receives a board on which the image sensor is mounted so that the image sensor faces the lens group; a cylindrical third housing that is coupled to the image side of the second housing and surrounds the image sensor module including the board from the outside; and a vibration mechanism that is provided in the first housing and has a vibrating body for vibrating a first lens of the lens group that is positioned closest to the object, and is characterized in that a vibration propagation limiting means is provided in a vibration propagation path along which vibrations from the first lens vibrated by the vibration mechanism propagate in sequence to the first housing, the second housing, and the third housing.

[0013] According to the above-described configuration of the present invention, since the vibration propagation limiting means is provided in the vibration propagation path along which the vibration from the first lens vibrated by the vibration mechanism propagates in sequence to the first housing, the second housing, and the third housing, it is possible to prevent the vibration energy from deteriorating due to the vibration propagation and the resulting deterioration of vibration performance. In other words, by suppressing the propagation of vibration between the housings, the desired vibration performance (vibration performance that enables the atomization of water droplets or the like adhering to the lens or cover) can be ensured, and noise due to impact or resonance between the housings can also be prevented.

[0014] In the above configuration, "limiting the propagation of vibration" means suppressing or blocking the propagation of vibration. "Vibration propagation path" refers to any path that can allow the propagation of vibration waves within the material that makes up the housing. The vibration propagation limiting means may be provided at any one or more positions in the vibration propagation path, but it is preferable to provide multiple vibration propagation limiting means at positions as close as possible to the object side.

[0015] In addition, the above-described configuration of the present invention preferably further includes a screw having a shank with threads formed thereon to be threaded onto a threaded portion of one housing to fasten the housings together, and a head formed at the end of the shank and abutting against the other housing, and the vibration propagation limiting means preferably includes a washer interposed between the head of the screw and the other housing. This arrangement, in particular, places the washer at a screw fastening location that is likely to become a vibration propagation path, thereby efficiently and effectively limiting vibration propagation. Here, "fastening the housings together" refers to fastening any two of the first to third housings together, and is not limited to fastening adjacent housings together. For example, it also includes fastening the first housing to the third housing with a screw. The washer may be made of any material, including highly elastic materials, as long as it can limit vibration propagation. Examples of suitable materials for the washer include rubber and silicone. Alternatively, materials such as plastic are also possible. A combination of multiple materials, such as metal and rubber, is also possible. Using rubber or silicone washers in conjunction with metal washers (e.g., stacking them together) allows for controlled (e.g., uniform) pressure on the washers.

[0016] In the above-described configuration of the present invention, the vibration propagation limiting means preferably includes a cushioning material inserted between the joint surfaces of the housings. This allows the cushioning material to be inserted at the joints of the housings, which are particularly prone to become vibration propagation paths, thereby efficiently and effectively limiting vibration propagation. Examples of such cushioning materials include Kapton (registered trademark) and EPDM (ethylene propylene rubber), but plastic materials are also possible.

[0017] The above-described configuration of the present invention is particularly useful in cases where the first, second, and third housings are made of different materials and vibrations are easily propagated.

[0018] The present invention also provides an in-vehicle system having the above-mentioned camera module, and a mobile body equipped with the in-vehicle system. Such in-vehicle systems and mobile bodies can achieve the same effects as the above-mentioned camera module. Note that the term "mobile body" refers to any object that can move, such as a vehicle.

[0019] According to the camera module of the present invention, the presence of the vibration propagation limiting means makes it possible to prevent deterioration of vibration energy due to vibration propagation and a drop in vibration performance. In other words, by suppressing the propagation of vibration between housings, it is possible to ensure the desired vibration performance and prevent noise.

[0020] 6 is a plan view of a camera module according to an embodiment of the present invention; FIG. 1 is a cross-sectional view taken along line A-A in FIG. 1; FIG. 1 is a cross-sectional view taken along line B-B in FIG. 1; FIG. 6 is experimental data showing the vibration displacement of a first lens caused by a vibration mechanism provided in a first housing, in a state where a housing having a rectangular cross section is fastened at its four corners with screws, with washers and buffer materials interposed at each location as vibration propagation limiting means, for each state where first to third housings made of different materials are joined in a stepwise manner; FIG. 6 is experimental data showing the vibration displacement of a first lens caused by a vibration mechanism provided in the first housing, in a state where a housing having a rectangular cross section is fastened at its four corners with screws, with washers and buffer materials interposed at each location as vibration propagation limiting means, for each state where first to third housings made of different materials are joined in a stepwise manner; FIG. 6 is a schematic diagram of a vehicle as a moving object on which an imaging system (on-board system) including a camera module according to an embodiment of the present invention is mounted; FIG. 6 is a block diagram showing the configuration of an imaging device constituting the imaging system of FIG. 6; This is experimental data showing the vibration displacement of the lens or lens cover caused by a vibration device provided on the first housing in a conventional state in which a housing with a rectangular cross section is fastened at its four corners with screws, when the first to third housings made of different materials are joined in stages.

[0021] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present embodiments contribute to the achievement of "9. Industry, innovation and infrastructure" of the Sustainable Development Goals (SDGs) advocated by the United Nations, which states, "9.1 Develop quality, reliable, sustainable and resilient infrastructure, including regional and transborder infrastructure, to support economic development and human well-being, with a focus on affordable and equitable access for all."

[0022] Fig. 1 is a plan view of a camera module 300 according to an embodiment of the present invention, Fig. 2 is a schematic cross-sectional view of the camera module 300 taken along line A-A in Fig. 1, and Fig. 3 is a schematic cross-sectional view of the camera module 300 taken along line B-B in Fig. 1. The camera module described below is particularly a camera module such as an in-vehicle camera, which is fixedly installed on the outer surface of a vehicle, for example, with wiring drawn into the vehicle and connected to a display or other device.

[0023] As shown in FIGS. 2 and 3, the camera module 300 of this embodiment is configured by accommodating various optical elements in a housing formed by joining a plurality of housing parts. Specifically, camera module 300 includes, as optical elements, a lens group L in which a plurality of lenses are arranged along the optical axes of the lenses, a cylindrical lens barrel 22 that houses and holds this lens group L, and an image sensor 304 that converts light focused through lens group L into an electrical signal. The housing is made up of a first housing 23 in the shape of a rectangular tube that forms an accommodation space inside to accommodate lens barrel 22 that houses and holds lens group L, a second housing 24 in the shape of a rectangular tube and approximately a thin dish that forms a recess 24g that houses a board 309 on which image sensor 304 is mounted so that image sensor 304 faces lens group L, and that determines the position of image sensor 304 in the optical axis direction, and a third housing 25 in the shape of a rectangular tube that surrounds image sensor module 310 including board 309 from the outside, and an extension 310A extending from image sensor module 310 protrudes outward from third housing 25. The housings 23, 24, and 25 are made of different materials, for example, the first housing 23 is made of stainless steel (SUS304), the second housing 24 is made of engineering plastic (PPS resin), and the third housing 25 is made of aluminum alloy (A5052). The imaging module 310 is formed by joining, for example, the upper board 309 on which the imaging element 304 is mounted and a lower board on which a circuit for performing image processing is mounted.

[0024] The image-side (lower side in FIG. 1 ) ends of the lens barrel 22 and the first housing 23 are supported by the second housing 24. The length of the second housing 24 in the optical axis direction is shorter than that of the first housing 23. The optical axis is indicated by O, and the direction perpendicular to this optical axis O is the radial direction.

[0025] The first housing 23 is disposed radially outward of the lens barrel 22, and the second housing 24 is disposed closer to the image (lower in FIG. 1 ) than the first housing 23. The lens barrel 22, first housing 23, second housing 24, and third housing 25 are disposed coaxially. A rectangular plate-shaped inner flange portion 24a is formed at the upper end of the second housing 24, and a convex portion 24b that protrudes toward the object side (upper in FIG. 1 ) is formed in the radial center of this inner flange portion 24a, and a through-hole 24c is formed in the radial center of this convex portion 24b.

[0026] A step 24d is formed on the upper surface of the inner flange 24a, and the lower end of the first housing 23 is fitted into this step 24d, thereby positioning the first housing 23 relative to the second housing 24 in the radial direction and the optical axis direction.

[0027] Furthermore, the lens unit 20 including the lens group L and the lens barrel 22 includes a plurality of (e.g., six) lenses 31, 32, 33, 34, 35, and 36 arranged in order from the object side. The lens 31 is a first lens 31 located closest to the object side, and this first lens 31 is held by a lens holding portion 50 (described later) in the first housing 23. The five lenses 32, 33, 34, 35, and 36 arranged closer to the image side than the first lens 31 are provided inside the lens barrel 22.

[0028] Furthermore, a cylindrical protrusion 27 that protrudes toward the image side (downward in FIG. 1) is formed at the lower end of the lens barrel 22, and this protrusion 27 is inserted into and fits into a through-hole 24c provided in the second housing 24. As a result, the lens barrel 22 and the second housing 24 are arranged coaxially and coincident with the optical axis O.

[0029] Furthermore, the first lens 31 located closest to the object is a glass lens, and the lenses 32 to 36 are resin lenses, but this is not limiting (for example, the lens 31 may be a resin lens). Furthermore, the surfaces of the lenses 31 to 36 may be provided with an anti-reflection film, a hydrophilic film, a water-repellent film, or the like, as needed.

[0030] The multiple lenses 31 to 36 fixed to and supported by the lens barrel 22 are arranged with their optical axes aligned, and the lenses 31 to 36 are arranged along a single optical axis O to form a group of lenses L used for imaging.

[0031] In this embodiment, the first housing 23 is disposed radially outward from the lens barrel 22. The first housing 23 is formed from a metal such as SUS and includes a rectangular cylindrical housing main body 23a, a top plate 23b that is short in the radial direction and formed integrally with the housing main body 23a at the upper end of the housing main body 23a, and a locking portion 23c that is formed integrally with the top plate 23b at the inner peripheral edge of the top plate 23b. The thickness of the top plate 23b (thickness in the optical axis direction) is thinner than the thickness of the housing main body 23a (thickness in the radial direction).

[0032] The locking portion 23c includes a generally cylindrical protrusion 23d formed to protrude from the inner peripheral edge of the top plate portion 23b toward the object side (upper side in FIG. 1 ) and a pressing portion 23e bent radially inward from the upper end of the protrusion 23d. An inclined surface 23f inclined with respect to the optical axis O is formed along the circumferential direction on the pressing portion 23e. The inclined surface 23f presses the surface edge of the first lens 31, thereby fixing the first lens 31. In other words, when the lens group L is assembled and housed in the first housing 23 and the lens barrel 22, the inclined surface 23f of the pressing portion 23e presses the first lens 31, which is located closest to the object side of the lens group L, and fixes it to the object-side end of the first housing 23 in the optical axis direction.

[0033] Furthermore, an inner flange portion 26 having an opening with a diameter smaller than that of the sixth lens 36 is provided at the image side end (the lower end in FIG. 1) of the lens barrel 22. The plurality of lenses 31 to 36 that make up the lens group L inside the first housing 23 and the lens barrel 22 are held and fixed in the optical axis direction by this inner flange portion 26 and the inclined surface 23f of the pressing portion 23e. Furthermore, a filter 99 such as an infrared cut filter is provided on the lower surface of the inner flange portion 26.

[0034] In this embodiment, a ring-shaped lens holder 50 is provided to hold the first lens 31. The lens holder 50 is manufactured by turning a metal such as stainless steel into a thin ring shape. The lens holder 50 has an inner peripheral surface 50a that is cylindrical and a toric surface 50b that is perpendicular to the inner peripheral surface 50a. The inner peripheral surface 50a and the toric surface 50b are formed to have an L-shaped cross section. The inner peripheral surface 50a is arranged coaxially with the optical axis O, and the toric surface 50b is arranged perpendicular to the optical axis O. The lens holder 50 also has an inner peripheral surface 50c that is perpendicular to the toric surface 50b and coaxial with the optical axis O. The inner peripheral surface 50c is arranged closer to the image side (lower in FIG. 1 ) than the inner peripheral surface 50a and has a smaller inner diameter than the inner peripheral surface 50a.

[0035] The inner diameter of the inner peripheral surface 50c of the ring-shaped lens holder 50 is larger than the outer diameter of the lens barrel 22, so that the upper end of the lens barrel 22 is located inside the inner peripheral surface 50c of the lens holder 50. The lens holder 50 is also joined to the first housing 23. That is, the outer peripheral surface 50d of the lens holder 50 abuts the inner peripheral surface of the protrusion 23d of the first housing 23 with almost no gap, so that the lens holder 50 fits into the locking portion 23c of the first housing 23. In this way, the lens holder 50 is joined to the first housing 23, which has the locking portion 23c. When the lens holder 50 is joined to the first housing 23, the axis of the lens holder 50 coincides with the optical axis O, and the lens holder 50 is positioned in the optical axis direction.

[0036] The lens holder 50 also holds the first lens 31. That is, the inner peripheral surface 50a of the lens holder 50 abuts tightly against the outer peripheral surface of the first lens 31, thereby positioning the first lens 31 in the radial direction and disposing it coaxially with the optical axis O. The annular surface 50b of the lens holder 50 abuts tightly against the flat bottom surface 31a of the first lens 31 facing the image side, thereby positioning the first lens 31 in the optical axis direction.

[0037] Furthermore, lenses 32 to 36, which are arranged closer to the image than the first lens 31, are held by the lens barrel 22 so that their optical axes are aligned, and the lens barrel 22 is arranged coaxially with the second housing 24 and aligned with the optical axis O, so that the first lens 31 and lenses 32 to 36, which are arranged closer to the image than the first lens 31, are arranged coaxially or with an eccentricity of less than a predetermined amount.

[0038] In this embodiment, a vibration mechanism 60 is provided to vibrate the first lens 31. The vibration mechanism 60 includes a vibrator 61 that generates ultrasonic vibrations and a vibrating body 62 that transmits the ultrasonic vibrations of the vibrator 61 to the first lens 31. The vibration mechanism 60 is housed within the first housing 23, positioned radially inward from the first housing 23 and radially outward from the lens barrel 22. The vibrator 61 is formed in the shape of an annular plate and is provided inside the housing body 23a of the first housing 23. The vibrator 61 is formed, for example, of a piezoelectric element. The vibration mechanism 60 having the vibrator 61 is separated from the second housing 24 by a predetermined gap s to avoid resonance (resonance and the associated noise) due to vibration.

[0039] The vibrating body 62 includes a donut-shaped disk-shaped mounting portion 62a, and a main body portion 62b that extends from the mounting portion 62a toward the object side (upward in FIG. 1), has an outer diameter and an inner diameter that continuously change in the axial direction (optical axis direction), has a generally cylindrical shape with bulges and constrictions, and has an S-shaped cross section. The vibrator 61 is fixed to the underside of the mounting portion 62a, and the upper end side of the main body portion 62b is integrally formed with the lens holder 50 described above.

[0040] In such vibration mechanism 60, vibrator 61 ultrasonically vibrates at a predetermined frequency, causing vibration body 62 to ultrasonically vibrate. When vibration body 62 vibrates, first lens 31 ultrasonically vibrates at the same frequency via lens holder 50 because vibration body 62 is integrated with lens holder 50, thereby removing foreign matter such as water droplets, muddy water, ice, snow, and frost from lens surface 31b of first lens 31.

[0041] The lens holder 50 is fitted into the top plate 23b (locking portion 23c) of the first housing 23, but the thickness of the top plate 23b is thinner than the thickness of the housing main body 23a, and the top plate 23b functions as a damper, so that vibrations of the lens holder 50 are less likely to be transmitted to the housing main body 23a. This makes it less likely that vibrations will be transmitted to the second housing 24 fitted into the housing main body 23a, and as a result, vibrations are less likely to be transmitted to the lens barrel 22 fitted into the second housing 24, and therefore to the lenses 32 to 36, thereby preventing a deterioration in optical performance caused by displacement of the lenses 32 to 36 due to vibrations.

[0042] In this embodiment, the lens unit 20 is made up of the first housing 23, the first lens 31 held in the first housing 23, the lens barrel 22, the lenses 32 to 36 held in the lens barrel 22, the lens holder 50, the vibration mechanism 60, etc. The camera module 300 of this embodiment is made up of the lens unit 20, the second housing 24 fitted into the first housing 23 of the lens unit 20, and the third housing 25 fitted into the second housing 24 and containing the imaging module.

[0043] The second housing 24 and the third housing 25 house therein an imaging module 310 including a board 309 on which an imaging element 304 (image sensor) is mounted. Specifically, the imaging module 310 occupies most of the interior space of the second and third housings 24, 25, and is disposed in the center of the interior of the third housing 25 with the board 309 on which the imaging element 304 (image sensor) is mounted being received and positioned in the recess 24g of the second housing 24.

[0044] The image sensor 304 serving as a package sensor is disposed inside the second housing 24 facing the filter 99, and is disposed in a position where it receives an image of an object formed by the lens unit 20. The image sensor 304 includes a CCD, a CMOS, or the like, and converts light that is collected through the lens unit 20 and reaches the image sensor 304 into an electrical signal. The converted electrical signal is then converted into analog data or digital data, which are components of the image data captured by the camera.

[0045] The third housing 25 also includes a drive circuit board 305 therein. The drive circuit board 305 is a board having a drive circuit that applies a voltage of a predetermined frequency to the piezoelectric element 61 of the vibration mechanism 60 to drive it. The drive circuit board 305 and the vibrator (piezoelectric element) 61 are connected by wiring 306 formed of an FPC or the like and passed through wiring holes 24f formed in the inner flange portion 24a of the second housing 24.

[0046] As described above, with the substrate 309 on which the image sensor 304 is mounted received in the recess 24g, the second housing 24 has a seal member 70 interposed between it and the third housing 25 (at the joint between the second housing 24 and the third housing 25) to keep the internal spaces of the housings 24, 25 airtight. As clearly shown in FIG. 3 , the second housing 24 is fastened to the first housing 23 by screws 80. In this case, the screws 80 are fastened at the four corners of the housings 23, 24, each having a rectangular cross section. Furthermore, since the first housing 23 is densely packed with components including the lens unit 20 and the vibration mechanism 60 as described above, and assembly is performed in order from the first housing 23 side to the second housing 24 and the third housing 25 side, the screws 80 are screwed into the threaded portions 83 of the first housing 23 from the second housing 24 side, with the heads 80a of the screws 80 positioned on the second housing 24 side. That is, the screw 80 has a shaft portion 80b with threads formed thereon that screws into the screw portion 83 of the first housing 23, and a head portion 80a formed at the end of the shaft portion 80b and abutted against the side of the second housing 24.

[0047] 3, the second housing 24 is also fastened to the third housing 25 by screws 85. In this case, too, the screws 85 are fastened at the four corners of the housings 24, 25, each having a rectangular cross section, and the screws 85 are threaded into the threaded portions 87 of the second housing 24 from the third housing 25 side, with the heads 85a of the screws 85 positioned on the third housing 25 side. That is, the screws 85 have a shaft portion 85b formed with a thread that screws into the threaded portions 87 of the second housing 24, and a head portion 85a formed at the end of the shaft portion 85b and abutting against the third housing 25 side.

[0048] Furthermore, in this embodiment, vibration propagation limiting means for limiting the propagation of vibration is provided in a vibration propagation path along which vibration from the first lens 31 vibrated by the vibration mechanism 60 propagates in sequence to the first housing 23, the second housing 24, and the third housing 25. Specifically, particularly in this embodiment, as the vibration propagation limiting means, washers 84 made of rubber or silicone are interposed between the heads 80 a of all four screws 80 and the second housing 24, and washers 89 made of rubber or silicone are interposed between the heads 85 a of all four screws 85 and the third housing 25.

[0049] Furthermore, in this embodiment, as vibration propagation limiting means, a buffer material 90 made of Kapton (registered trademark; polyimide film) is inserted in the joint surface (contact surface) between the first housing 23 and the second housing 24, and a buffer material 92 made of EPDM (ethylene propylene rubber) is inserted in the joint surface (contact surface) between the second housing 24 and the third housing 254.

[0050] In addition to the screws and the joint surface, the lens holder may be considered as a vibration propagation path, and in addition to the buffer material and washer, adhesive or the like may be considered as a vibration propagation limiting means.

[0051] 4 shows experimental data by the present inventors, which shows the vibration displacement of the first lens 31 caused by the vibration mechanism 60 in each state where the first to third housings 23, 24, 25 made of different materials are joined in stages, with the rectangular housings 23, 24, 25 fastened at their four corners with screws 80, 85, with the washers 84, 89 and cushioning materials 90, 92 described above interposed at each location as vibration propagation limiting means. The solid line in the figure represents the case of "no measures" in which no vibration propagation limiting means is provided, and is the experimental data described above with reference to FIG. In addition, dashed line a indicates a case in which cushioning material 90 is inserted at the joint surface between the first housing 23 and the second housing 24 (cushioning material 92 and washers 84, 89 are not provided), dotted line b indicates a case in which washers 84 are provided on four screws 80 (cushioning materials 90, 92 and washer 89 are not provided), three-dotted line c indicates a case in which cushioning material 92 is inserted at the joint surface between the second housing 24 and the third housing 25 (cushioning material 90 and washers 84, 89 are not provided), and two-dotted line d indicates a case in which washers 89 are provided on four screws 85 (cushioning materials 90, 92 and washer 84 are not provided). In all cases, the amount of vibration displacement of the first lens 31 decreases as the state shifts from the first housing 23 alone (the second and third housings 24, 25 are not joined) to the state in which the second housing 24 is fastened and joined to the image side of the first housing 23, to the state in which the third housing 25 is further fastened and joined to the image side of the second housing 24 (the first, second, and third housings 23, 24, 25 are all fastened and joined to each other), but it can be seen that the reduction in the amount of vibration displacement is small when cushioning materials 90, 92 or washers 84, 89 are provided as vibration propagation limiting means. In particular, it was found that vibration propagation can be effectively limited when washers 84, 89 are provided on the screws 80, 85.

[0052] FIG. 5 shows experimental data obtained by the inventors in which washers 84, 89 and buffer materials 90, 92 were individually inserted at multiple locations as vibration propagation limiting means. The solid line in the figure represents the "no measures" case in which no vibration propagation limiting means was provided, and corresponds to the experimental data described above with reference to FIG. 9 . The two-dot chain line b+d represents a combination of lines b and d in FIG. 4, in which washers 84 were provided on the four screws 80 and washers 89 were also provided on the four screws 85. The three-dot chain line a+b+c+d represents a combination of all the cases in FIG. 4, in which washers 84 were provided on the four screws 80 and washers 89 were also provided on the four screws 85, buffer materials 90 were inserted at the joint surfaces between the first housing 23 and the second housing 24, and buffer materials 92 were inserted at the joint surfaces between the second housing 24 and the third housing 25. In either case, the decrease in the vibration displacement of the first lens 31 can be significantly suppressed.

[0053] As described above, according to this embodiment, the vibration propagation limiting means 84, 89, 90, and 92 are provided on the vibration propagation path along which the vibrations from the first lens 31 vibrated by the vibration mechanism 60 propagate in sequence to the first housing 23, the second housing 24, and the third housing 25. This makes it possible to prevent the vibration energy from deteriorating due to the vibration propagation and to prevent a decrease in vibration performance. In other words, by suppressing the propagation of vibration between the housings 23, 24, and 25, the desired vibration performance (vibration performance that enables the atomization of water droplets and the like adhering to the lens 31) can be ensured, and noise due to impacts and resonance between the housings 23, 24, and 25 can also be prevented.

[0054] FIG. 6 schematically illustrates a vehicle 240 as a moving object equipped with an in-vehicle system (imaging system) including an imaging device 250 including the camera module 300 shown in FIGS. 1 to 3 . As illustrated, the imaging device 250 can be mounted on the vehicle 240, and FIG. 6 illustrates an example of the mounting position of the imaging device 250 on the vehicle 240. The imaging device 250 mounted on the vehicle 240 can also be called an in-vehicle camera and can be installed in various locations on the vehicle 240. For example, the first imaging device 250a may be disposed on or near the front bumper as a camera that monitors the front of the vehicle 240 while the vehicle 240 is traveling. The second imaging device 250b that monitors the front of the vehicle 240 may be disposed near an inner rearview mirror inside the vehicle 240. The third imaging device 250c may be disposed on the dashboard, in the instrument panel, or the like as a camera that monitors the driver's driving status. The fourth image capturing device 250d may be installed at the rear of the vehicle 240 to monitor the rear of the vehicle 240. The image capturing devices 250a and 250b may be called front cameras. The third image capturing device 250c may be called an in-camera. The fourth image capturing device 250d may be called a rear camera. The image capturing device 250 is not limited to these, and may include image capturing devices installed at various positions, such as a left side camera that captures the left rear side and a right side camera that captures the right rear side.

[0055] An image signal of an image captured by the imaging device 250 may be output to an information processing device (controller) 242 and / or a display device (output device) 243 in the vehicle 240. The information processing device 242 and the display device 243, together with the imaging device 250, constitute an in-vehicle system. The information processing device 242 in the vehicle 240 includes a device that processes the image signal (captured image) acquired by the imaging device 250 and recognizes the image (recognizing objects in the captured image) to assist the driver in driving. The information processing device 242 is configured to output recognition information of objects in the captured image to the display device 243, and examples of such devices include, but are not limited to, a navigation system, a collision damage mitigation braking system, a vehicle-to-vehicle distance control device, and a lane departure warning system. The display device 243 displays the image processed and output by the information processing device 242, but can also receive an image signal directly from the imaging device 250. The display device 243 may be, but is not limited to, a liquid crystal display (LCD), an organic electroluminescence (EL) display, or an inorganic EL display. The display device 243 can display to the driver (can output information to the occupants) an image signal output from an imaging device 250 that captures an image from a position that is difficult for the driver to see, such as a rear camera.

[0056] Fig. 7 shows the configuration of an imaging device that constitutes the in-vehicle system of Fig. 6. As shown in the figure, an imaging device 250 according to one embodiment includes a control unit 252, a storage unit 254, and the camera module 300 shown in Figs. 1 to 3.

[0057] The control unit 252 controls the camera module 300 and processes the electrical signal output from the image sensor 304 of the camera module 300. The control unit 252 may be configured as, for example, a processor. The control unit 252 may also include one or more processors. The processor may include a general-purpose processor that loads a specific program to execute a specific function, and a dedicated processor specialized for a specific process. The dedicated processor may include an application-specific integrated circuit (IC). An application-specific IC is also called an application-specific integrated circuit (ASIC). The processor may include a programmable logic device. A programmable logic device is also called a programmable logic device (PLD). A PLD may include a field-programmable gate array (FPGA). The control unit 252 may be either a system-on-a-chip (SoC) or a system-in-a-package (SiP) in which one or more processors work together. In addition, the control unit 252 may have the same functions as the information processing device 242 described above, and may, for example, process the captured image output from the image sensor 304 and recognize objects in the captured image.

[0058] The storage unit 254 stores various information or parameters related to the operation of the imaging device 250. The storage unit 254 may be configured with, for example, a semiconductor memory or the like. The storage unit 254 may function as a work memory for the control unit 252. The storage unit 254 may store captured images. The storage unit 254 may store various parameters and the like that are used by the control unit 252 to perform detection processing based on the captured images. The storage unit 254 may be included in the control unit 252.

[0059] As described above, the camera module 300 captures an image of a subject formed via the lens unit 20 with the image sensor 304 and outputs the captured image. The image captured by the camera module 300 is also referred to as a captured image.

[0060] The imaging element 304 may be configured, for example, as a complementary metal oxide semiconductor (CMOS) image sensor or a charge coupled device (CCD). The imaging element 304 has an imaging surface on which a plurality of pixels are arranged. Each pixel outputs a signal specified by a current or voltage according to the amount of incident light. The signal output by each pixel is also referred to as imaging data.

[0061] The imaging data may be read by the camera module 300 for all pixels and captured by the control unit 252 as a captured image. A captured image read by all pixels is also referred to as a maximum captured image. The imaging data may be read by the camera module 300 for some pixels and captured as a captured image. In other words, the imaging data may be read from pixels in a predetermined capture range. The imaging data read from pixels in the predetermined capture range may be captured as a captured image. The predetermined capture range may be set by the control unit 252. The camera module 300 may acquire the predetermined capture range from the control unit 252. The imaging element 304 may capture an image of a predetermined capture range from the subject image formed via the lens unit 20.

[0062] The present invention is not limited to the above-described embodiments and can be modified in various ways without departing from the spirit of the invention. For example, the shapes of the lens, housing, lens barrel, etc. are not limited to those of the above-described embodiments. Furthermore, some or all of the above-described embodiments may be combined, or part of the configuration of one of the above-described embodiments may be omitted, without departing from the spirit of the invention.

[0063] 20 Lens unit 22 Lens barrel 23 First housing 24 Second housing 25 Third housing 31 First lens 60 Vibration mechanism 80, 85 Screws 84, 89 Washers (vibration propagation limiting means) 90, 92 Cushioning material (vibration propagation limiting means) 300 Camera module 304 Image pickup element 310 Image pickup module L Lens group

Claims

1. A camera module comprising a lens group in which multiple lenses are arranged along the optical axis of each lens, a lens barrel that houses and holds this lens group, and an image sensor that converts light focused through the lens group into an electrical signal, comprising: a cylindrical first housing that forms an internal storage space to receive the lens barrel that houses and holds the lens group; a second housing that is coupled to the image side of the first housing and forms a recess that receives a board on which the image sensor is mounted so that the image sensor faces the lens group; a cylindrical third housing that is coupled to the image side of the second housing and surrounds the image sensor module including the board from the outside; and a vibration mechanism that is provided in the first housing and has a vibrating body for vibrating the first lens of the lens group that is positioned closest to the object; and the camera module is characterized in that it has a vibration propagation limiting means for limiting the propagation of vibrations from the first lens vibrated by the vibration mechanism along a vibration propagation path that propagates in turn through the first housing, the second housing, and the third housing.

2. A camera module as described in claim 1, further comprising a screw having a shaft portion with threads formed thereon that is screwed onto the threaded portion of one of the housings to fasten the housings together, and a head portion formed at the end of the shaft portion and abutting against the other housing, wherein the vibration propagation limiting means includes a washer interposed between the head of the screw and the other housing.

3. A camera module according to claim 1 or 2, characterized in that the vibration propagation limiting means includes a cushioning material inserted between the joint surfaces of the housings.

4. The camera module according to claim 3, wherein the first, second and third housings are made of different materials.

5. An in-vehicle system to be mounted on a vehicle, comprising: a camera module according to claim 1; and a control unit that processes an image output from the imaging element of the camera module and recognizes an object in the image.

6. A mobile body equipped with the in-vehicle system according to claim 5 and an output device that outputs information to an occupant, wherein the control unit is configured to output the recognition information of the object to the output device.

Images