Lens unit, camera module, on-vehicle system, moving body, and method for assembling lens unit

Abstract

Provided are a lens unit in which air bubbles mixed in an adhesive layer for joining a vibrating body and a lens can be removed and uniform propagation of ultrasonic vibration can be ensured, a camera module, an on-vehicle system, a moving body, and a method for assembling the lens unit.　This lens unit has a vibrating body 62 that has one end connected to a vibration source and transmits ultrasonic vibration of the vibration source to a first lens 31. The other end 50 of the vibrating body 62 is fitted to a housing 23, and is held by the housing 23 together with the first lens 31 by an adhesive 70 that joins the first lens 31, the housing 23, and the vibrating body 62 to each other. A groove 80 for communicating the adhesive 70 with a gas phase space is formed on the adhesive surface to which the adhesive 70 is applied.

Description

Lens Unit, Camera Module, Vehicle-mounted System, Moving Body, and Method for Assembling Lens Unit

[0001] The present invention relates to a lens unit, a camera module, a vehicle-mounted system, a moving body equipped with the vehicle-mounted system, and a method for assembling a lens unit, which constitute an in-vehicle camera mounted on a vehicle such as an automobile, for example.

[0002] Conventionally, in-vehicle cameras have been mounted on automobiles to support parking or prevent collisions through image recognition, and attempts have also been made to apply them to autonomous driving. In addition, such camera modules, such as in-vehicle cameras, generally include a lens unit having a lens group in which a plurality of lenses are arranged along an optical axis, a lens barrel (barrel) that houses and holds the lens group, and an aperture member disposed between at least one pair of lenses in the lens group (see, for example, Patent Document 1).

[0003] Further, such a lens unit may be attached to an attachment portion such as a front grille of a vehicle (automobile), and the lens located closest to the object side may be exposed to the outside. In such a case, foreign substances such as water droplets, muddy water, ice and snow, and frost are likely to adhere to the surface (lens surface) of the lens, and when they adhere, it is necessary to remove the foreign substances in order to ensure a clear observation field by the lens unit.

[0004] Regarding the removal of foreign substances adhering to the surface of a lens (or lens cover), in recent years, foreign substances have also been removed by vibrating the lens (or lens cover) with a vibrator (ultrasonic vibration). For example, in Patent Document 2, a vibration device for removing foreign substances 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 11, such a vibrating device 102 is installed in a camera that has an imaging unit 105 containing a lens 106 and an image sensor at the top of the camera body 103, and comprises a dome-shaped transparent cover 111, a cylindrical vibrating body 112 to which the cover 111 is fixed, and a piezoelectric element 113 fixed to the vibrating body 112 that 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 of the cover 111; a tubular first connecting portion 115 connected to the first end 114a of the cylindrical portion 114 and made of a cylinder with a larger inner diameter than the cylindrical portion 114; a first ring-shaped portion 116 interposed between the first connecting portion 115 and the cover 111 and having a smaller inner diameter than the first connecting portion 115; a second connecting portion 117 connected to the second end 114b of the cylindrical portion 114 and made of a cylinder with a smaller outer diameter than 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 a larger outer diameter than the second connecting portion 117. Furthermore, all components of this small camera module, including the camera body 103 and the vibration device 102, are housed within the housing 130.

[0006] In such a vibrating device 102, the piezoelectric element 113 is driven to cause ultrasonic vibration of the cover 111 via the vibrating body 112, thereby more effectively moving and atomizing the liquid droplets, or removing foreign matter adhering to the surface of the cover 111.

[0007] Japanese Patent Publication No. 2013-231993, Japanese Patent Publication No. 6977784

[0008] By the way, in the configuration shown in Figure 11, the vibrating body 112 needs to be coupled to the cover 111 (or to the lens if the lens is to be vibrated) by some means. In that case, if the vibrating body 112 is coupled to the cover 111 with adhesive, one problem may arise.

[0009] In other words, when the vibrator 112 is bonded to the cover 111 with adhesive, vibrations from the vibrator 112 are transmitted to the cover 111 through a layer of adhesive of a predetermined thickness. If air bubbles are present in the adhesive layer, and if the bubbles are mixed in an uneven manner, the propagation of ultrasonic vibrations will become uneven, which may limit the vibration performance. In particular, if uneven vibration propagation is repeated during long-term use, the bonding strength between the cover 111 and the vibrator 112 will decrease, as will the airtightness inside the camera module, which may threaten the reliability of the required lens unit.

[0010] The present invention has been made in view of the above circumstances, and aims to provide a lens unit, camera module, in-vehicle system, and mobile body, as well as a method for assembling a lens unit, that can remove air bubbles mixed in the adhesive layer that joins the vibrating body and the lens, and ensure uniform propagation of ultrasonic vibrations.

[0011] To solve the above problems, the present invention provides a lens unit comprising a lens group in which a plurality of lenses are arranged along the optical axis of the lens, a vibration mechanism for vibrating a first lens located closest to an object among the plurality of lenses, and a housing for housing the lens group and the vibration mechanism, wherein the vibration mechanism comprises a vibration source that vibrates ultrasonically and a vibrating body whose one end is connected to the vibration source and which transmits the ultrasonic vibration of the vibration source to the first lens, the other end of the vibrating body is fitted into the housing and is held in the housing together with the first lens by an adhesive that connects the first lens, the housing and the vibrating body to each other, and grooves are formed on the adhesive surface to which the adhesive is applied to allow the adhesive to communicate with the gas phase space.

[0012] According to the above configuration of the present invention, since grooves are formed on the bonding surface to which the adhesive is applied, allowing the adhesive to communicate with the gas phase space, even if air bubbles are mixed into the adhesive, these air bubbles can escape into the gas phase space through the grooves. Therefore, it is possible to avoid situations where the propagation of ultrasonic vibrations becomes uneven due to the presence of air bubbles, or where the bonding strength between the first lens and the vibrator decreases due to repeated vibration propagation, or where the airtightness inside the camera module decreases. In other words, according to the above configuration, air bubbles mixed into the adhesive layer that bonds the vibrator, the first lens, and the housing can be effectively removed, uniform propagation of ultrasonic vibrations can be ensured, and a highly reliable lens unit can be provided. Furthermore, the above configuration of the present invention is particularly beneficial in situations where the vibrator forms a fitted structure with the housing, making it difficult to visually inspect the adhesive on the bonding surface of these fitted parts (visual inspection of the state of air bubbles mixed into the adhesive), and where it is difficult for air bubbles to escape, as it can completely eliminate air bubbles.

[0013] Furthermore, in the above configuration, since the vibrating body and the housing are fitted together, the housing holds the vibrating body in place together with the first lens. As a result, the vibrating body acts as an internal vibrating body and the housing acts as an external vibrating body, allowing the first lens to be effectively vibrated ultrasonically without any loss of vibration.

[0014] Furthermore, in the above configuration of the present invention, the first lens, which is located closest to the object among the lens group, can be effectively vibrated ultrasonically by the vibrating body. This makes it possible to remove foreign matter such as water droplets and dust adhering to the first lens by vibration, thereby ensuring a consistently clear field of view.

[0015] In the above configuration, "gas phase space" refers to any space filled with air, such as the internal space of the lens unit or the external space of the lens unit with outside air, from which air bubbles can escape.

[0016] Furthermore, in the above configuration, it is preferable that grooves be formed on the bonding surface so as to allow air bubbles mixed into the adhesive to escape into the gas phase space. In this case, examples of bonding surfaces on which such grooves are formed include the inner circumferential surface of the housing that fits with the other end of the vibrator, the outer circumferential surface of the other end of the vibrator that fits with the housing, or the inner circumferential surface of the other end of the vibrator that fits with the first lens. In addition, if the housing and the other end of the vibrator are fitted together by screwing a male thread formed on the outer circumferential surface of the other end of the vibrator into a female thread formed on the inner circumferential surface of the housing, it is preferable that grooves deeper than the height of the threads are formed on the female or male thread.

[0017] Furthermore, the present invention provides a method for assembling a lens unit that includes the steps of: applying adhesive to the bonding surface of the grooved lens unit as described above; temporarily assembling the first lens, vibrator, and housing of the lens unit to which the adhesive has been applied using a jig; setting the temporarily assembled lens unit in a vacuum degassing device and reducing the pressure inside the vacuum degassing device to remove air bubbles mixed in the adhesive through the grooves into the gas phase space; and thermally curing the adhesive from which the air bubbles have been removed. With this method, air bubbles in the adhesive can be actively removed through the grooves by vacuuming, thus efficiently and reliably resolving the aforementioned problems associated with air bubbles.

[0018] Furthermore, the present invention also provides a camera module having the aforementioned lens unit, an in-vehicle system, and a mobile body equipped with the in-vehicle system. The same effects as those of the aforementioned lens unit can be obtained with such a camera module, in-vehicle system, and mobile body. The term "mobile body" refers to all objects that can be moved, such as vehicles.

[0019] According to the lens unit of the present invention, air bubbles mixed into the adhesive layer that joins the vibrating body and the lens can be removed, and uniform propagation of ultrasonic vibrations can be ensured.

[0020] This is a schematic cross-sectional view of a camera module having a lens unit according to one embodiment of the present invention. This is a perspective view of the camera module of Figure 1. This is an enlarged cross-section of the main part near the mating portion between the first lens with a grooved adhesive surface, the housing, and the vibrator. (a) is a perspective view of the housing as seen from the image side, showing a state in which a groove is formed on the inner circumferential surface of the housing that mates with the other end of the vibrator, and (b) is an enlarged cross-section of the main part near the mating portion between the first lens with a grooved adhesive surface, the housing, and the vibrator. This is a perspective view of the vibrator showing a state in which a groove is formed on the outer circumferential surface of the other end of the vibrator that mates with the housing. (a) is a perspective view of the vibrator showing a state in which a groove is formed on the inner circumferential surface of the other end of the vibrator that mates with the first lens, and (b) is an enlarged cross-section of the main part near the mating portion between the first lens with a grooved adhesive surface, the housing, and the vibrator. This is a perspective view of the vibrator showing a state in which a groove is formed on the male screw on the outer circumferential surface of the other end of the vibrator that mates with the housing. This is a flowchart showing the steps of a method for removing air bubbles in adhesive by vacuum degassing. This is a schematic diagram of a vehicle as a mobile body on which an imaging system (in-vehicle system) equipped with a camera module according to one embodiment of the present invention is mounted. This is a block diagram showing the configuration of the imaging device constituting the imaging system in Figure 9. This is a schematic cross-sectional view of a conventional camera module.

[0021] The embodiments of the present invention will be described below with reference to the drawings. These embodiments contribute to "9. Build resilient infrastructure, including local and transboundary infrastructure, to support economic development and human well-being, with a focus on affordable and equitable access for all," which is one of the Sustainable Development Goals (SDGs) advocated by the United Nations.

[0022] Figure 1 is a schematic cross-sectional view of a camera module equipped with a lens unit according to one embodiment of the present invention, and Figure 2 is a perspective view of this camera module. The lens unit described below is particularly for camera modules such as in-vehicle cameras, and is, for example, fixedly installed on the outer surface of a vehicle, with wiring routed into the vehicle and connected to a display or other device.

[0023] As shown in Figures 1 and 2, the camera module 300 of this embodiment includes a lens unit 20. This lens unit 20 comprises a cylindrical lens barrel 22 and a rectangular tubular first housing (housing) 23 in which the lens barrel 22 is provided.

[0024] Furthermore, the image-side (lower side in Figure 1) end of the lens barrel 22 and the first housing 23 is supported by a rectangular cylindrical second housing 24. The second housing 24 is shorter than the first housing 23 in the optical axis direction, but its outer and inner diameters are longer than those 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 positioned radially outward from the lens barrel 22, and the second housing 24 is positioned on the image side (downward in Figure 1) than the first housing 23. The lens barrel 22, the first housing 23, and the second housing 24 are arranged 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 is formed at the radial center of this inner flange portion 24a, projecting toward the object side (upward in Figure 1), and a through hole 24c is formed at the radial center of this convex portion 24b.

[0026] Furthermore, a stepped portion 24d is formed on the upper surface of the inner flange portion 24a, and the lower end of the first housing 23 is fitted into this stepped portion 24d. This positions the first housing 23 relative to the second housing 24 in the radial and optical axis directions.

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

[0028] Furthermore, a cylindrical projection 27 is formed at the lower end of the lens barrel 22, projecting toward the image side (downward in Figure 1). This projection 27 is inserted into and fitted into the through hole 24c provided in the second housing 24. As a result, the lens barrel 22 and the second housing 24 are positioned coaxially with each other and coaxially with the optical axis O.

[0029] Furthermore, the first lens 31, which is located closest to the object, is a glass lens, and lenses 32 to 36 are resin lenses, but this is not limited to them (for example, lens 31 may also be a resin lens). In addition, anti-reflective coatings, hydrophilic coatings, water-repellent coatings, etc., may be provided on the surfaces of lenses 31 to 36 as needed.

[0030] Multiple lenses 31 to 36, fixed and supported by the first housing 23 and lens barrel 22, are arranged so that their respective optical axes are aligned, and the lenses 31 to 36 are lined up along a single optical axis O, forming a group of lenses L used for imaging.

[0031] Furthermore, in this embodiment, the first housing 23 is positioned radially outward of the lens barrel 22. The first housing 23 is made of a metal such as SUS, and comprises a rectangular cylindrical housing body 23a, a rectangular plate-shaped top plate portion 23b integrally formed with the housing body 23a at the upper end of the housing body 23a, and a locking portion 23c integrally formed with the top plate portion 23b at the inner circumferential edge of the top plate portion 23b. The thickness of the top plate portion 23b (thickness in the optical axis direction) is thinner than the thickness of the housing body 23a (thickness in the radial direction).

[0032] The locking portion 23c comprises a substantially cylindrical projection 23d formed projecting from the inner circumferential edge of the top plate portion 23b toward the object side (upward in Figure 1), and a pressing portion 23e bent radially inward from the upper end of the projection 23d. An inclined surface 23f is formed on the pressing portion 23e along the circumferential direction, inclined with respect to the optical axis O. The first lens 31 is fixed by pressing its surface edge with the inclined surface 23f. In other words, with the lens group L assembled and housed within the first housing 23 and lens barrel 22, the inclined surface 23f of the pressing portion 23e presses the first lens 31, which is located furthest toward the object in the lens group L, and fixes it to the object-side end of the first housing 23 in the direction of the optical axis.

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

[0034] Furthermore, in this embodiment, a ring-shaped lens holder 50 is provided for holding the first lens 31. This lens holder 50 is manufactured by turning a metal such as SUS to form a thin ring shape. The lens holder 50 has a cylindrical inner surface 50a and an annular surface 50b perpendicular to the inner surface 50a on its inner circumference side, and the inner surface 50a and the annular surface 50b are formed in an L-shape in cross-section. The inner surface 50a is arranged coaxially with the optical axis O, and the annular surface 50b is arranged perpendicular to the optical axis O. In addition, the lens holder 50 has an inner surface 50c perpendicular to the annular surface 50b and arranged coaxially with the optical axis O, and this inner surface 50c is located on the image side (lower side in Figure 1) than the inner surface 50a, and has a smaller inner diameter than the inner surface 50a.

[0035] Furthermore, the inner diameter of the inner circumferential 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 positioned inside the inner circumferential surface 50c of the lens holder 50. The lens holder 50 is also joined to the first housing 23 in a fitted state. That is, the outer circumferential surface 50d and the upper surface 50e of the lens holder 50 are in contact with the inner circumference of the retaining portion 23e of the first housing 23 with virtually no gap, so that the lens holder 50 is fitted to the retaining portion 23e of the first housing 23. In this way, the lens holder 50 is joined to the first housing 23 having the retaining portion 23e in a fitted state. The lens holder 50 joined to the first housing 23 in a fitted state has its axis coincide with the optical axis O and is positioned in the direction of the optical axis.

[0036] Furthermore, the lens holder 50 holds the first lens 31. That is, the inner circumferential surface 50a of the lens holder 50 is in close contact with the outer circumferential surface of the first lens 31, thereby positioning the first lens 31 radially and aligning it coaxially with the optical axis O. Also, the annular surface 50b of the lens holder 50 is in close contact with the flat bottom surface 31e of the first lens 31 facing the image side, thereby positioning the first lens 31 in the direction of the optical axis. In addition, the lenses 32 to 36, which are positioned closer to the image side than the first lens 31, are held by the lens barrel 22 so that their optical axes coincide. Since the lens barrel 22 is provided coaxially with the second housing 24 and coincides with the optical axis O, the first lens 31 and the lenses 32 to 36, which are positioned closer to the image side than the first lens 31, are positioned coaxially or with an eccentricity of less than a predetermined amount.

[0037] Furthermore, in this embodiment, a vibration mechanism 60 is provided for vibrating the first lens 31. The vibration mechanism 60 comprises a transducer 61 as a vibration source that vibrates ultrasonically, and a vibrating body 62 that transmits the ultrasonic vibration of the transducer 61 to the first lens 31. Such a vibration mechanism 60 is arranged radially inward from the first housing 23 and radially outward from the lens barrel 22. That is, the first housing 23 houses the lens group L and the vibration mechanism inside. The transducer 61 is formed in the shape of an annular plate and is provided inside the housing body 23a of the first housing 23. The transducer 61 is formed by, for example, a piezoelectric element.

[0038] The vibrating body 62 is made of, for example, metal and comprises a donut-shaped mounting portion 62a as one end connected to the vibrator 61, a roughly cylindrical body portion 62b extending from the mounting portion 62a toward the object side (upward side in Figure 1), with a bulge and constriction in the axial direction (optical axis direction) due to the continuous change in outer and inner diameters, and an S-shaped cross-section, and a ring-shaped joint portion 62c formed at the upper end of the body portion 62b. The vibrator 61 is attached and fixed to the lower surface of the mounting portion 62a, and the upper surface of the joint portion 62c is bonded to the lower surface (image-facing surface) of the lens holder 50 with adhesive.

[0039] In this type of vibration mechanism 60, the vibrator 61 vibrates ultrasonically at a predetermined frequency, causing the vibrating body 62 to vibrate ultrasonically. When the vibrating body 62 vibrates, since the vibrating body 62 is joined to the lens holder 50, the first lens 31 vibrates ultrasonically at the same frequency via the lens holder 50, thereby removing foreign matter such as water droplets, mud, ice, snow, and frost that has accumulated on the lens surface 31a of the first lens 31.

[0040] The lens holder 50 is fitted into the retaining portion 23e of the first housing 23. However, the thickness of the top plate portion 23b that forms the retaining portion 23e is thinner than the thickness of the housing body 23a, and the top plate portion 23b (retaining portion 23e) functions as a damper, so that vibrations from the lens holder 50 are less likely to be transmitted to the housing body 23a. As a result, vibrations are less likely to be transmitted to the second housing 24 fitted into the housing body 23a, and consequently, vibrations are less likely to be transmitted to the lens barrel 22 fitted into the second housing 24, and also less likely to be transmitted to the lenses 32-36, thereby suppressing a decrease in optical performance caused by displacement of the lenses 32-36 due to vibration. On the other hand, as mentioned above, the vibrating body 62 and the first housing 23 are fitted together, and the first housing 23 holds down the vibrating body 62 together with the first lens 31. As a result, the vibrating body 62 acts as an internal vibrating body and the first housing 23 acts as an external vibrating body, allowing the first lens 31 to be effectively vibrated ultrasonically without any loss of vibration.

[0041] In this embodiment, the lens unit 20 is composed of a first housing 23, a first lens 31 held in the first housing 23, a lens barrel 22, lenses 32-36 held in the lens barrel 22, a lens holder 50, a vibration mechanism 60, and the like. The camera module 300 of this embodiment is composed of this lens unit 20 and a second housing 24 fitted into the first housing 23 of the lens unit 20. The second housing 24 is equipped with a package sensor (image sensor) 304 inside.

[0042] The package sensor 304 is positioned inside the second housing 24, facing the filter 99, and is located in a position to receive the image of the object formed by the lens unit 20. The package sensor 304 is equipped with a CCD or CMOS sensor, and converts the light that is focused and reaches it through the lens unit 20 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.

[0043] Further, the second housing 24 includes a drive circuit board 305 inside thereof. The drive circuit board 305 is a board having a drive circuit 4 (see FIG. 3) 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 formed by an FPC or the like and are connected by a wiring 306 passed through a wiring hole 24f formed in the inner flange portion 24 of the second housing 24.

[0044] Incidentally, in the above configuration, the first lens 31, the first housing 23, and the lens holding portion 50 that are fitted to each other are adhesively fixed with an adhesive using their fitting surfaces as adhesive surfaces. In this case, as described above, the vibration from the vibrating body 62 is transmitted to the first lens 31 through a layer of the adhesive having a predetermined thickness. Therefore, if air bubbles are present in the adhesive layer and the air bubbles are mixed in a non-uniform state, the propagation of ultrasonic vibration becomes non-uniform, and there is a risk that the vibration performance is limited. In particular, when non-uniform vibration propagation is repeated during long-term use, the bonding strength between the cover 111 and the vibrating body 112 decreases, and the airtightness inside the camera module also decreases, and the required reliability of the lens unit may be threatened. In particular, when the first lens 31, the lens holding portion 50, and the first housing 23 form a fitting structure, it is difficult to visually recognize the adhesive on the adhesive surfaces of these fitting portions (visually recognize the state of air bubbles mixed in the adhesive), and there is a situation where it is difficult for air bubbles to escape, and improvement is required.

[0045] Therefore, hereinafter, a structure capable of removing air bubbles mixed in such an adhesive will be described. Hereinafter, it will be described on the assumption that the lens holding portion 50 and the vibrating body 62 are integrated, and the other end portion (upper end portion) of the vibrating body 62 forms the lens holding portion 50. Therefore, hereinafter, for the sake of convenience, in the vibrating body 62, the reference numeral and name of the lens holding portion 50 are directly adopted.

[0046] Figure 3 is an enlarged cross-section of the main part near the fitting portion between the first lens 31, the pressing portion 23e of the first housing 23, and the other end (the lens holding portion mentioned above) 50 of the vibrating body 60. As shown in the figure, adhesive 70 is applied to all of the fitting surfaces of the first lens 31, the pressing portion 23e of the first housing 23, and the other end 50 of the vibrating body 60, namely the inner circumferential surface of the first housing 23 (pressing portion 23e) that fits with the other end 50 of the vibrating body 62, the outer circumferential surface of the other end 50 of the vibrating body 62 that fits with the first housing 23 (pressing portion 23e), the inner circumferential surface of the other end 50 of the vibrating body 62 that fits with the first lens 31, and the inner circumferential surface of the first housing 23 (pressing portion 23e) that fits with the first lens 31, using these as bonding surfaces. As a result, the other end 50 of the vibrating body 62 is held to the first housing 23 together with the first lens 31 by adhesive 70.

[0047] Furthermore, in order to effectively remove air bubbles that may be introduced into these adhesives 70 (for example, due to incomplete application of adhesive during assembly of the lens unit 20), as an example, as shown in Figure 4, a plurality of grooves 80 are formed on the inner circumferential surface of the retaining portion 23e of the first housing 23, which is the bonding surface that fits with the other end 50 of the vibrating body 62, so as to release air bubbles introduced into the adhesive 70 applied thereto into the gas phase space, specifically into the internal space S1 of the lens unit 20 formed between the vibrating body 62 and the first housing 23. These grooves 80 are formed over the entire inner circumferential surface of the retaining portion 23e that extends in the radial and optical axis directions and fits with the outer circumferential surfaces 50d, 50e (upper surface 50e) of the other end 50 of the vibrating body 62, or at least over the portion of the inner circumferential surface of the retaining portion 23e that extends in the optical axis direction and fits with the outer circumferential surface 50d of the other end 50 of the vibrating body 62. Furthermore, these grooves 80 are provided along the circumferential direction of the inner surface of the pressing portion 23e at equal angular intervals (for example, 45-degree intervals) from each other, and communicate with the gas phase space S1. If the adhesive 70 is not applied, these grooves form a gap between the pressing portion 23e of the first housing 23 and the other end 50 of the vibrating body 62 when they are fitted together.

[0048] Due to the formation of such a groove 80, when an adhesive is applied (filled) to the bonding surface including the groove 80 and the first lens 31, the pressing portion 23e of the first housing 23, and the other end portion 50 of the vibrating body 60 are assembled in a fitted state, along with the flow of the adhesive 70 at that time, the air bubbles mixed into the adhesive 70 can escape into the gas phase space S1. Therefore, due to the presence of air bubbles, situations such as the propagation of ultrasonic vibration becoming non-uniform, or the bonding strength between the first lens 31 and the vibrating body 62 decreasing due to repeated vibration propagation, or the airtightness inside the camera module 300 decreasing can also be avoided. That is, according to the above configuration of the present embodiment, air bubbles mixed into the layer of the adhesive 70 that joins the vibrating body 62, the first lens 31, and the first housing 23 can be effectively removed, uniform propagation of ultrasonic vibration can be ensured, and a highly reliable lens unit 20 can be provided. Further, by arranging the layer of the adhesive 70 in the shear direction in this way, it becomes possible to form a more tough structure body.

[0049] As the cross-sectional shape of the groove 80, various shapes such as circular (arc-shaped), rectangular, and triangular can be adopted. Also, the depth (sagitta) of the groove 80 can be arbitrarily set. In particular, in the case of the groove 80 having an arc-shaped cross-section, the fitting portion of the vibrating body 62 with the first housing 23 can be integrally processed, and higher accuracy and efficiency can be achieved compared to conventional processing methods. In particular, by setting the ratio of the radius of curvature of the arc-shaped groove 80 to the fitting diameter of the first housing 23 and the ratio of the sagitta of the arc-shaped groove 80 to the radius to predetermined values, the fitting portion and the vertical groove can be arranged in a well-balanced manner. As an example, when eight vertical grooves are provided, if each ratio is 0.2, it is possible to achieve both ensuring a sufficient fitting surface, the bonding strength of the groove portion, and the discharge of air bubbles. Therefore, it is expected to contribute to the improvement of productivity and cost reduction in the manufacturing industry.

[0050] In addition, when the holding portion 50 and the vibrating body 62 are separate as depicted in FIG. 1, such a groove 80 is provided in the holding portion 50. Further, a retainer (not shown) that holds the first lens 31 is fitted and provided so as to cover the pressing portion 23e of the first housing 23 from the outside, or is provided in place of the pressing portion 23e, and when an adhesive is applied to the bonding surface of this retainer, the groove 80 may be provided in this retainer.

[0051] Figures 5 to 7 show modified forms of the groove 80. In the modified form shown in Figure 5, a plurality of grooves 80 are formed on the outer circumferential surface of the other end 50 of the vibrating body 62, which fits with the retaining portion 23e of the first housing 23, to release air bubbles mixed in the adhesive 70 applied thereto into the gas phase space, specifically into the internal space S1 of the lens unit 20 formed between the vibrating body 62 and the first housing 23. These grooves 80 are formed over the entire outer circumferential surfaces 50d and 50e of the other end 50 of the vibrating body 62 that fits with the inner circumferential surface of the retaining portion 23e, extending in the radial and optical axis directions, or at least over the portion of the outer circumferential surface 50d of the other end 50 of the vibrating body 62 that extends in the optical axis direction. Furthermore, these grooves 80 are provided along the circumferential direction of the outer surface of the other end 50 of the vibrating body 62, separated by equal angular intervals (for example, 45-degree intervals), and communicate with the gas phase space S1. If the adhesive 70 is not applied, these grooves form a gap between the pressing portion 23e of the first housing 23 and the other end 50 of the vibrating body 62 when they are fitted together.

[0052] In the modified example shown in Figure 6, a plurality of grooves 80 are formed on the inner circumferential surface of the other end 50 of the vibrating body 62 that fits with the first lens 31. These grooves 80 are formed to allow air bubbles mixed into the adhesive 70 applied thereto to escape into the gas phase space, specifically into the internal space S2 of the lens unit 20 formed between the vibrating body 62 and the lens barrel 22. These grooves 80 are formed over the entire inner circumferential surface 50a, 50b (annular surface 50b) of the other end 50 of the vibrating body 62 that fits with the first lens 31, extending in the radial and optical axis directions. These grooves 80 are also provided along the circumferential direction of the inner circumferential surface of the other end 50 of the vibrating body 62 at equal angular intervals (for example, 45-degree intervals) from each other, communicating with the gas phase space S2. If the adhesive 70 is not applied, these grooves form a gap between the first lens 31 and the other end 50 of the vibrating body 62 when they are fitted together.

[0053] In the modified example shown in Figure 7, the first housing 23 and the other end 50 of the vibrating body 62 are fitted together by screwing a male thread 62d formed on the outer circumferential surface of the other end 50 of the vibrating body 62 into a female thread formed on the inner circumferential surface of the retaining portion 23e of the first housing 23. In this screw-fit structure as well, a plurality of grooves 80 are formed on the threaded outer circumferential surface of the other end 50 of the vibrating body 62, which serves as the bonding surface for screwing with the retaining portion 23e of the first housing 23, so as to release air bubbles mixed into the adhesive 70 applied thereto into the gas phase space, specifically into the internal space S1 of the lens unit 20 formed between the vibrating body 62 and the first housing 23. Furthermore, these grooves 80 are formed as grooves deeper than the height of the threads of the male thread 62d. In addition, these grooves 80 are provided along the circumferential direction of the outer circumferential surface of the other end 50 of the vibrating body 62 at equal angular intervals (for example, 45-degree intervals) from each other, so as to communicate with the gas phase space S1. With this configuration, a strong joint can be achieved by improving the pull-out force with screws and preventing the screws from loosening with adhesive.

[0054] Furthermore, the groove formation configuration may be a combination of the configurations shown in Figures 4 to 7, either partially or entirely.

[0055] Furthermore, Figure 8 shows a method for removing air bubbles from the adhesive 70 during assembly of the lens unit 20 through the groove 80 described above. In this method, first, as a preparation step, the bonding surfaces of the first lens 31, the vibrator 62, and the first housing 23 are appropriately cleaned. Also, the thermosetting adhesive 70 is degassed with a stirrer and set in a dispenser. Then, as described above with respect to Figure 3, the adhesive 70 is applied from the dispenser in an amount sufficient to form an adhesive layer to the bonding surface (fitting surface) of the lens unit 20 (step S1). Subsequently, the first lens 31, vibrator 62, and first housing 23 of the lens unit to which the adhesive 70 has been applied are temporarily assembled using a jig (step S2). After that, the temporarily assembled lens unit 20 is set in a vacuum degassing device (not shown), and the pressure inside the vacuum degassing device is reduced to remove air bubbles mixed in the adhesive 70 through the groove 80 into the gas phase space S1 (or S2) (step S3). Finally, the lens unit 20 is placed in a heating device to heat-cur the adhesive 70 from which the air bubbles have been removed (step S4). With this method, air bubbles in the adhesive 70 can be actively removed through the groove 80 by vacuum, thus efficiently and reliably resolving the aforementioned problems associated with air bubbles.

[0056] Figure 9 schematically shows a vehicle 240 as a mobile body on which an in-vehicle system (imaging system) comprising an imaging device 250 including the camera module 300 of Figure 1 is mounted. As shown in the figure, the imaging device 250 can be mounted on the vehicle 240, and Figure 9 is an example of an arrangement illustrating 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 placed on or near the front bumper as a camera that monitors the area in front of the vehicle 240 while it is in motion. The second imaging device 250b, which also monitors the area in front, may be placed near the rearview mirror inside the vehicle 240. The third imaging device 250c may be placed on the dashboard or inside the instrument panel, etc., as a camera that monitors the driver's driving conditions. The fourth imaging device 250d may be installed at the rear of the vehicle 240 for use as a rear monitor. Imaging devices 250a and 250b can be called front cameras. The third imaging device 250c can be called an in-camera. The fourth imaging device 250d can be called a rear camera. The imaging device 250 is not limited to these, and includes imaging devices installed in various positions, such as a left side camera that images the left rear side and a right side camera that images the right rear side.

[0057] The image signal of the image captured by the imaging device 250 can be output to an information processing device (control unit) 242 and / or a display device (output device) 243, etc., within the vehicle 240. These information processing devices 242 and 243 together with the imaging device 250 constitute an in-vehicle system. The information processing device 242 within the vehicle 240 includes a device that processes the image signal (captured image) acquired by the imaging device 250, recognizes the image (recognizes objects in the captured image), and assists the driver in driving. The information processing device 242 is also configured to output recognition information of objects in the captured image to the display device 243, and includes, but is not limited to, a navigation device, a collision damage mitigation braking device, a vehicle-to-vehicle distance control device, and a lane departure warning device. The display device 243 displays the image processed and output by the information processing device 242, but can also receive the image signal directly from the imaging device 250. The display device 243 may employ, but is not limited to, a liquid crystal display (LCD), an organic electro-luminescence (OLED) display, and an inorganic EL display. The display device 243 can display image signals output from the imaging device 250, which captures images from positions that are difficult for the driver to see, such as a rear camera, to the driver (it can output information to the occupants).

[0058] Figure 10 shows the configuration of the imaging device that constitutes the in-vehicle system shown in Figure 9. As shown in the figure, the imaging device 250 according to one embodiment includes a control unit 252, a storage unit 254, and the camera module 300 shown in Figure 1.

[0059] The control unit 252 controls the camera module 300 and processes the electrical signals output from the image sensor 304 of the camera module 300. This control unit 252 may be configured as a processor, for example. The control unit 252 may also include one or more processors. The processors may include general-purpose processors that load specific programs and execute specific functions, and dedicated processors specialized for specific processing. Dedicated processors may include application-specific integrated circuits (ICs). Application-specific integrated circuits are also called ASICs (Application Specific Integrated Circuits). The processors may also include programmable logic devices. Programmable logic devices are also called PLDs (Programmable Logic Devices). PLDs may include field-programmable gate arrays (FPGAs). 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 cooperate. Furthermore, the control unit 252 may have the same functions as the information processing device 242 described above. For example, it may process the captured image output from the image sensor 304 to recognize an object in the captured image.

[0060] The storage unit 254 stores various information or parameters related to the operation of the imaging device 250. The storage unit 254 may be composed of, for example, a semiconductor memory. 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, etc., for 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.

[0061] As mentioned above, the camera module 300 captures the subject image 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 called the captured image.

[0062] The image sensor 304 may be composed of, for example, a CMOS (Complementary Metal Oxide Semiconductor) image sensor or a CCD (Charge Coupled Device). The image sensor 304 has an imaging surface in which multiple pixels are arranged. Each pixel outputs a signal that is specified by current or voltage according to the amount of incident light. The signal output by each pixel is also called imaging data.

[0063] The image data may be read out by the camera module 300 for all pixels and taken into the control unit 252 as an image. The image data read out for all pixels is also called the maximum image. The image data may be read out by the camera module 300 for some pixels and taken into the image. In other words, the image data may be read out from pixels within a predetermined acquisition range. The image data read out from pixels within a predetermined acquisition range may be taken into the image. The predetermined acquisition range may be set by the control unit 252. The camera module 300 may obtain the predetermined acquisition range from the control unit 252. The image sensor 304 may capture an image within a predetermined acquisition range from the subject image formed via the lens unit 20.

[0064] It should be noted that the present invention is not limited to the embodiments described above, and can be implemented with various modifications without departing from its spirit. For example, in the present invention, the shapes of lenses, housings, lens barrels, etc., are not limited to the embodiments described above. Furthermore, without departing from the spirit of the present invention, some or all of the embodiments described above may be combined, or some components of one of the embodiments described above may be omitted.

[0065] 20 Lens unit 22 Lens barrel 23 First housing 24 Second housing 31 First lens 60 Vibration mechanism 61 Vibrator (vibration source) 62 Vibrating body 70 Adhesive 80 Groove 300 Camera module 304 Image sensor 310 Image module L Lens group

Claims

1. A lens unit comprising a lens group consisting of a plurality of lenses arranged along the optical axis of the lens, a vibration mechanism for vibrating a first lens located closest to an object among the plurality of lenses, and a housing for housing the lens group and the vibration mechanism, wherein the vibration mechanism comprises a vibration source that vibrates ultrasonically and a vibrating body having one end connected to the vibration source and transmitting the ultrasonic vibration of the vibration source to the first lens, the other end of the vibrating body being fitted into the housing and held in the housing together with the first lens by an adhesive that connects the first lens, the housing and the vibrating body to each other, and grooves formed on the adhesive surface to which the adhesive is applied for communicating the adhesive to the gas phase space.

2. The lens unit according to claim 1, characterized in that the groove is formed on the inner circumferential surface of the housing which is the adhesive surface that fits with the other end of the vibrating body, so as to allow air bubbles mixed into the adhesive to escape into the gas phase space.

3. The lens unit according to claim 1, characterized in that the groove is formed on the outer peripheral surface of the other end of the vibrating body that fits with the housing, which serves as the adhesive surface, so as to allow air bubbles mixed into the adhesive to escape into the gas phase space.

4. The lens unit according to claim 3, characterized in that the housing and the other end of the vibrating body are fitted together by screwing a male thread formed on the outer circumferential surface of the other end of the vibrating body into a female thread formed on the inner circumferential surface of the housing, and the groove is formed in the female thread or the male thread that is deeper than the height of the thread.

5. The lens unit according to claim 1, characterized in that the groove is formed on the inner circumferential surface of the other end of the vibrating body that fits with the first lens, which serves as the adhesive surface, so as to allow air bubbles mixed into the adhesive to escape into the gas phase space.

6. A camera module comprising a lens unit according to any one of claims 1 to 5, and an image sensor that converts light collected through the lens group of the lens unit into an electrical signal.

7. An in-vehicle system mounted on a vehicle, comprising: a camera module as described in claim 6; and a control unit that processes an image captured from the image sensor of the camera module to recognize an object in the image captured.

8. A mobile body equipped with the in-vehicle system described in claim 7 and an output device that outputs information to the occupants, wherein the control unit is configured to output recognition information of the object to the output device.

9. A method for assembling a lens unit, comprising the steps of: applying the adhesive to the bonding surface of the lens unit described in claim 1; temporarily assembling the first lens, the vibrating body, and the housing of the lens unit to which the adhesive has been applied using a jig; setting the temporarily assembled lens unit in a vacuum degassing device and reducing the pressure inside the vacuum degassing device to remove air bubbles mixed in the adhesive through the grooves into the gas phase space; and thermally curing the adhesive from which the air bubbles have been removed.

Images