Lens unit and camera module

Abstract

To provide a lens unit capable of preventing fogging of a back surface of a first lens and deterioration of optical performance by reliably waterproofing a lens space between the first lens and a second lens without using an O-ring, and to provide a camera module.SOLUTION: A first lens 13 located on the most object side among a plurality of lenses and a second lens 14 located next to the first lens 13 on the image side are waterproof bonded together using a low-moisture-permeability adhesive ad, thereby reliably waterproofing a space between the first lens 13 and a lens barrel 12 without using an O-ring to prevent fogging of a back surface of the first lens 13 and deterioration of optical performance.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a lens unit and a camera module that can constitute an in-vehicle camera mounted on a vehicle such as an automobile.

Background Art

[0002] There is known a technique in which a camera mounted on a vehicle (in-vehicle camera) images a scenery outside the vehicle and the captured image is displayed on a monitor or the like mounted inside the vehicle. Since the lens unit of the in-vehicle camera is in a state where the side facing the imaging target (object side) is exposed to the outside of the vehicle, strength, waterproofness, chemical resistance, high-temperature durability, etc. are required. In addition, it is necessary to prevent fogging of the lens due to temperature changes.

[0003] Patent Document 1 discloses a lens unit that secures an airtight state inside the lens barrel in order to prevent fogging of the lens. In this lens unit, four lenses are arranged side by side along the optical axis direction inside the lens barrel. On the object side, a sealing property is achieved by arranging an elastic sealing member such as an O-ring between the first lens on the object side and the inner peripheral surface of the lens barrel. Also, on the image side (imaging element side), the sealing property is achieved by attaching an optical filter to the lens barrel via an adhesive. In this way, the airtightness inside the lens barrel is ensured by the sealing on the object side and the sealing on the imaging side, and fogging of the lens is prevented.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] By the way, as described above, when the first lens is waterproofed by an O-ring (elastic sealing member), if the O-ring is poorly attached due to being caught in the lens barrel or the like, moisture easily enters the lens space between the outermost lens (first lens) and the second lens adjacent to the first lens on the image side in a high-humidity environment. When the outside air temperature drops, the back surface of the outermost lens on the object side is likely to become foggy due to condensation. In addition, since the O-ring (elastic sealing member) is arranged in a compressed state between the first lens and the inner peripheral surface of the lens barrel, the first lens receives a reaction force due to the elastic restoring force of the O-ring. As a result, if the first lens is displaced in the optical axis direction, the optical performance deteriorates. In addition, since it is necessary to incorporate an O-ring into the lens barrel, the number of component parts increases and it also takes time to attach the O-ring.

[0006] The present invention has been made in view of the above circumstances, and an object thereof is to provide a lens unit and a camera module that can surely waterproof the lens space between the first lens and the second lens without using an O-ring, prevent fogging of the back surface of the first lens, and prevent deterioration of optical performance.

Means for Solving the Problems

[0007] In order to solve the above problems, the present invention provides a lens unit including a plurality of lenses arranged along an optical axis and a lens barrel that houses and holds these plurality of lenses, Among the plurality of lenses, the first lens located on the object side and an optical component adjacent to the first lens on the image side are adhesively waterproofed by a low moisture permeability adhesive.

[0008] Examples of the low moisture permeability adhesive include acrylic adhesives, epoxy adhesives, and olefin adhesives. In addition, when the second lens is adjacent to the first lens on the image side, or when a spacer, an optical filter, etc. that maintain the distance in the optical axis direction between the lenses are adjacent, the "optical component" includes the second lens, the spacer, and the optical filter.

[0009] In the present invention, since the first lens located closest to the object side and the optical component adjacent to the first lens on the image side are adhesively waterproofed with a low moisture permeability adhesive, even without using an O-ring, moisture hardly enters the lens space between the first lens and the second lens even in a high humidity environment. Therefore, even when the outside air temperature drops, fogging due to dew condensation on the back surface of the first lens can be prevented. Further, since an O-ring is not used, deterioration of optical performance due to the first lens receiving a reaction force from the O-ring and shifting in the optical axis direction can be prevented. Further, since an O-ring is not used, the number of component parts does not increase, and there is no trouble in attaching the O-ring.

[0010] Also, in the above configuration of the present invention, the first lens and the lens barrel may be adhesively waterproofed with a low moisture permeability adhesive.

[0011] According to such a configuration, since the first lens and the lens barrel are adhesively waterproofed with a low moisture permeability adhesive, it becomes difficult for moisture to enter the lens barrel from between the first lens and the lens barrel, so fogging due to dew condensation on the back surface of the first lens can be more reliably prevented.

[0012] Also, in the above configuration of the present invention, the outer peripheral surface of the first lens and the inner peripheral surface of the lens barrel may be adhesively waterproofed with the low moisture permeability adhesive.

[0013] The inner peripheral surface of the lens barrel may be roughened by sandblasting or the like in order to increase the adhesive strength by low moisture permeability adhesion.

[0014] According to such a configuration, since the outer peripheral surface of the first lens and the inner peripheral surface of the lens barrel are adhesively waterproofed with a low moisture permeability adhesive, moisture flowing from the object side surface of the first lens to the outer peripheral surface can be more reliably waterproofed.

[0015] Further, in the above configuration of the present invention, the end face on the image side of the first lens and the surface intersecting the axial direction of the lens barrel may be adhesively waterproofed with the low moisture permeability adhesive. The intersecting surface is preferably a surface perpendicular to the axial direction of the lens barrel, but may be inclined with respect to the axial direction.

[0016] According to such a configuration, since the end face on the image side of the first lens and the surface intersecting the axial direction of the lens barrel are adhesively waterproofed with the low moisture permeability adhesive, even if the low moisture permeability adhesive that waterproofs the space between the outer peripheral surface of the first lens and the inner peripheral surface of the lens barrel is damaged by an impact or the like and moisture enters the lens barrel, it is possible to surely prevent the moisture from entering the space on the back surface of the first lens. Further, since the low moisture permeability adhesive exists in both the axial direction of the lens barrel and the direction intersecting the axial direction, when an impact is applied to the lens unit, it becomes difficult for either one of the low moisture permeability adhesives to be damaged, so the responsiveness to impact is good.

[0017] Further, in the above configuration of the present invention, the low moisture permeability adhesive may have an elastic modulus of 1 to 1000 MPa and a Tg of 40°C to 60°C.

[0018] The elastic modulus indicates an index of the ease of moisture passage of the low moisture permeability adhesive. When the elastic modulus is less than 1 MPa, the flexibility of the low moisture permeability adhesive increases and moisture easily passes through. On the other hand, when it exceeds 1000 MPa, the low moisture permeability adhesive becomes too hard and is likely to be damaged when receiving an impact. Therefore, it is preferable that the elastic modulus of the low moisture permeability adhesive is 1 to 1000 MPa. Tg is the glass transition temperature of the low moisture permeability adhesive. When Tg exceeds 60°C, the low moisture permeability adhesive becomes too hard and the first lens is likely to be damaged. On the other hand, when it is less than 40°C, the low moisture permeability adhesive becomes too soft and moisture easily passes through (the waterproof property deteriorates). Therefore, it is preferable that Tg is 40°C to 60°C.

[0019] According to such a configuration, the first lens and the second lens located on the most object side can be more surely waterproofed with the low moisture permeability adhesive, and damage to the first lens can be prevented.

[0020] Further, the camera module according to the present invention is characterized by including the lens unit. According to such a configuration, the operational effects of the above-described lens unit can be obtained by the camera module.

Effects of the Invention

[0021] According to the present invention, without using an O-ring between the first lens located closest to the object side and the lens barrel, reliable waterproofing can be achieved, fogging on the back surface of the first lens can be prevented, and deterioration of optical performance can be prevented.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Modes for Carrying Out the Invention

[0023] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the lens unit of the present embodiment described below is particularly for a camera module such as an in-vehicle camera. For example, it is fixedly installed on the outer surface side of an automobile, and the wiring is drawn into the automobile and connected to a display or other devices. The lens unit of the present embodiment described below is particularly for a camera module such as an in-vehicle camera. For example, it is fixedly installed on the outer surface side of an automobile, and the wiring is drawn into the automobile and connected to a display or other devices. Also, hatching is omitted for the lenses in all the figures.

[0024] (First Embodiment) FIG. 1 shows a lens unit 11 according to the first embodiment of the present invention. As shown in the figure, the lens unit 11 of the present embodiment includes, for example, a cylindrical lens barrel (barrel) 12 made of resin, and a plurality of lenses arranged in the stepped inner accommodation space S of the lens barrel 12. For example, from the object side (upper side in FIG. 1), there are five lenses including a first lens 13, a second lens 14, a third lens 15, a fourth lens 16, and a fifth lens 17, and two aperture members 22a and 22b.

[0025] Of the two aperture members 22a and 22b, the first aperture member 22a from the object side is arranged between the second lens 14 and the third lens 15. The second aperture member 22b from the object side is arranged between the third lens 15 and the fourth lens 16. The aperture members 22a and 22b are either an "aperture stop" that restricts the amount of transmitted light and determines the F value, which is an indicator of brightness, or a "light-shielding stop" that shields light rays that cause ghosts or light rays that cause aberrations. An in-vehicle camera including such a lens unit 11 includes the lens unit 11, a substrate having an image sensor (not shown), and an installation member (not shown) for installing the substrate on a vehicle such as an automobile.

[0026] A plurality of lenses 13, 14, 15, 16, 17 incorporated and accommodated in the inner accommodation space S of the lens barrel 12 are stacked and arranged with their respective optical axes aligned, and are arranged in a state where each lens 13, 14, 15, 16, 17 is arranged along one optical axis O, constituting a group of lens groups L used for imaging. In this case, the first lens 13 located on the most object side among the lens groups L is a spherical glass lens having a convex surface on the object side and a concave surface 13c on the image side, and the second lens 14 adjacent to the first lens 13 on the image side is a resin lens having a concave surface 14c on the object side. The other lenses 15, 16, 17 including the second lens 14 are resin lenses, but are not limited thereto (for example, the first lens 13 may be a resin lens; when the first and second lenses 13, 14 are made of resin, the first lens 13 and the second lens 14 may have a difference in linear expansion coefficient of 40×10 -6 / K(m) or more).

[0027] In this embodiment, the number of lenses, the materials of the lenses and the lens barrel, etc. can be arbitrarily set according to the application and the like. Also, in this embodiment, the two fourth and fifth lenses 16, 17 located on the image side are bonded lenses, but this is not necessary. Note that, if necessary, an antireflection film, a hydrophilic film, a water-repellent film, etc. are provided on the surfaces of these lenses 13, 14, 15, 16, 17. Also, in this embodiment, different from the conventional case, an elastic sealing member such as an O-ring is not provided in the lens barrel.

[0028] Also, with the lens group L incorporated and accommodated in the inner accommodation space S of the lens barrel 12, the caulking portion 23 at the object-side end portion (the upper end portion in FIG. 1) of the lens barrel is thermally caulked radially inward, thereby fixing the first lens 13 located on the most object side of the lens group L to the object-side end portion of the lens barrel 12 in the optical axis direction by this caulking portion 23. In this case, in order to perform stable caulking, the portion of the glass lens 13 where the caulking portion 23 is pressed is formed as a flat portion 13b that is cut obliquely in a planar shape.

[0029] Also, an inner flange portion 24 having an opening smaller in diameter than the fifth lens 17 is provided at the image side end portion (the lower end portion in FIG. 1) of the lens barrel 12. The inner flange portion 24 and the caulking portion 23 hold and fix a plurality of lenses 13, 14, 15, 16, 17 constituting the lens group L and the diaphragm members 22a, 22b in the optical axis direction within the lens barrel 12.

[0030] The inner diameter of the lens barrel 12 gradually decreases from the object side toward the image plane side. Correspondingly, the outer diameters of the lenses 13, 14, 15, 16, 17 decrease from the object side toward the image plane side. Basically, the outer diameter of each of the lenses 13, 14, 15, 16, 17 is substantially equal to the inner diameter of each portion of the lens barrel 12 where the respective lenses 13, 14, 15, 16, 17 are supported. An outer flange portion 25 used when installing the lens barrel 12 in an in-vehicle camera is provided in a flange shape on the outer peripheral surface of the lens barrel 12.

[0031] FIG. 2 is a schematic cross-sectional view of the camera module 300 of the present embodiment having the lens unit 11 shown in FIG. 1. As shown in the figure, the camera module 300 includes the lens unit 11 to which the filter 105 is attached.

[0032] The camera module 300 includes an upper case (camera case) 301 which is an exterior component, and a mount (pedestal) 302 that holds the lens unit 11. The camera module 300 also includes a seal member 303 and a package sensor (imaging element) 304.

[0033] The upper case 301 is a member that exposes the object side end portion of the lens unit 11 and covers other portions. The mount 302 is disposed inside the upper case 301 and has a female screw 302a that engages with the male screw 11a of the lens unit 11. The seal member 303 is a member inserted between the inner surface of the upper case 301 and the outer peripheral surface of the lens barrel 12 of the lens unit 11, and is a member for maintaining the airtightness inside the upper case 301.

[0034] The package sensor 304 is disposed inside the mount 302 and at a position where an image of an object formed by the lens unit 11 is received. Further, the package sensor 304 includes a CCD, a CMOS, etc., and converts the light that is condensed and reaches through the lens unit 11 into an electrical signal. The converted electrical signal is converted into analog data or digital data that is a component of the image data captured by the camera. The filter 105 is adhered to the lower surface of the inner flange portion 24 with a low moisture permeability adhesive ad.

[0035] In the lens unit 11 and the camera module 300 having the above-described configuration, the first lens 13 located closest to the object side and the second lens 14 adjacent to the first lens 13 on the image side are adhesively waterproofed with a low moisture permeability adhesive ad (hereinafter, also referred to as a radial low moisture permeability adhesive ad) so that the space k between the lenses is sealed from the outside. The space k between the lenses is a space formed between a concave surface 13c formed on the image-side end surface of the first lens 13 and a concave surface 14c formed on the object-side end surface of the second lens 14. As shown in FIG. 1(a), the image-side end surface 13a of the first lens 13 is formed as an annular plane, and the object-side end surface 14a of the second lens 14 is formed as an annular plane. Then, a low moisture permeability adhesive ad is interposed between the inner peripheral side surface of the end surface 13a and the end surface 14a, and the first lens 13 and the second lens 14 are adhesively waterproofed so that the space k between the lenses is sealed from the outside by the low moisture permeability adhesive ad.

[0036] Further, a hydrophilic film 13m is provided on the concave surface 13c of the first lens 13 so as to cover the entire concave surface 13c. By providing the hydrophilic film 13m, fogging of the concave surface 13c on the back side of the first lens 13 can be prevented. However, when foreign matter adheres to the hydrophilic film 13m, the hydrophilic film 13m may deteriorate when irradiated with UV light, resulting in deterioration of optical performance. However, in the present embodiment and the second to fourth embodiments described later, the first lens 13 and the second lens 14 are adhesively waterproofed by a low moisture permeability adhesive ad so that the space k between the lenses is sealed from the outside, and dust is also prevented. Therefore, foreign matter does not adhere to the hydrophilic film 13m, and deterioration of the hydrophilic film 13m can be prevented.

[0037] Further, the outer peripheral surface of the first lens 13 and the inner peripheral surface of the lens barrel 12 are adhesively waterproofed by a low moisture permeability adhesive ad (hereinafter, also referred to as an axial low moisture permeability adhesive ad). In the present embodiment, a filling portion 30 filled with the low moisture permeability adhesive ad is provided on the inner peripheral surface of the lens barrel 12 so as to extend in the circumferential direction. The filling portion 30 is formed by notching the inner peripheral surface of the lens barrel 12 into a ring groove shape with a rectangular cross section, extends in the axial direction of the lens barrel 12, and has a bottom surface 30a at the image side end. Such a filling portion 30 is formed on the inner peripheral surface of the lens barrel 12 before caulking the caulking portion 23 (shown by a two-dot chain line in FIG. 1). Then, before caulking the caulking portion 23, the filling portion 30 is filled with the low moisture permeability adhesive ad, and after filling, the caulking portion 23 is caulked. As a result, the outer peripheral surface of the first lens 13 and the inner peripheral surface of the lens barrel 12 are adhesively waterproofed by the axial low moisture permeability adhesive ad. When the first lens 13 and the second lens 14 are adhesively waterproofed by a radial low moisture permeability adhesive ad, before caulking the caulking portion 23, the low moisture permeability adhesive ad is applied to at least one of the end surface 13a of the first lens 13 and the end surface 14a of the second lens 14, and then the first lens 13 is placed on the second lens 14 from above (from the object side) and incorporated into the lens barrel 12. When filling the filling portion 30 with the low moisture permeability adhesive ad, the low moisture permeability adhesive ad is filled from the upper end opening of the filling portion 30. Since the filling portion 30 has a bottom surface 30a at the lower end, the low moisture permeability adhesive ad to be filled stops flowing down at the bottom surface 30a. Therefore, it is possible to prevent the low moisture permeability adhesive ad from entering the lens barrel 12 beyond the outer peripheral surface of the first lens 13 or the inner peripheral surface of the lens barrel 12.

[0038] Also, in this embodiment, only one filling portion 30 is formed. However, by forming a plurality of filling portions 30 at predetermined intervals in the axial direction of the lens barrel 12, a plurality of axial low moisture permeability adhesives ad may be provided at predetermined intervals in the axial direction. When the outer peripheral surface of the first lens 13 can be adhesively fixed to the inner peripheral surface of the lens barrel 12 with a predetermined axial adhesive strength by the axial low moisture permeability adhesive ad, the caulking portion 23 may not be provided.

[0039] Also, as a modification, as shown in FIG. 2(b), a filling portion 31 filled with the axial low moisture permeability adhesive ad may extend in the circumferential direction on the outer peripheral surface of the first lens 13. Such a filling portion 31 also has a bottom surface 31a on the image side. In this modification, there is no caulking portion 23, and the first lens 13 is fixed to the lens barrel 12 by the axial low moisture permeability adhesive ad. However, a caulking portion 23 may be provided, and the first lens 13 may be fixed by this caulking portion 23.

[0040] Examples of the low moisture permeability adhesive include acrylic adhesives, epoxy adhesives, and olefin adhesives. The viscosity of these adhesives is preferably 10 Pa·S or more. If the viscosity is less than 10 Pa·S, the axial low moisture permeability adhesive ad is likely to flow down toward the lower side (image side), making it difficult to incorporate the first lens 13 into the lens barrel while ensuring the waterproof property between its outer peripheral surface and the inner peripheral surface of the lens barrel 12.

[0041] Epoxy adhesives have higher adhesive strength than acrylic adhesives, but are inferior in impact resistance. Therefore, when the lens unit 11 is subjected to a thermal shock test, the epoxy adhesive may peel off. For this reason, it is preferable to use an acrylic adhesive that is superior in impact resistance to the epoxy adhesive, but there is a risk that the adhesive strength may be insufficient. Therefore, when using an acrylic adhesive as the axially low moisture permeability adhesive ad, it is preferable to roughen the inner peripheral surface of the lens barrel 12 and / or the outer peripheral surface of the first lens 13 by means of roughening such as sandblasting. Further, when using an acrylic adhesive as the radially low moisture permeability adhesive ad, it is preferable to roughen the end face 13a of the first lens 13 and / or the end face 14a of the second lens 14 by means of roughening such as sandblasting. In such a case, it is preferable that the root mean square surface roughness Rq is about 0.01 μm to 200 μm. Further, when using an acrylic adhesive as the low moisture permeability adhesive ad, it is preferable to increase the adhesive area in order to ensure the adhesive strength.

[0042] Since the metal lens barrel 12 has better adhesiveness of the adhesive than the resin lens barrel 12, in the case of the metal lens barrel 12, it may not be necessary to roughen the inner peripheral surface or the flat surface 12c of the lens barrel 12, but roughening is preferable because the adhesiveness of the low moisture permeability adhesive ad is improved. Further, since the epoxy adhesive has higher adhesive strength than the acrylic adhesive, the epoxy adhesive may be used as the radially low moisture permeability adhesive ad. In this way, there is an advantage that the deviation of the optical axis of the first lens 13 can be prevented. Furthermore, since the epoxy adhesive is harder than the acrylic adhesive, when the epoxy adhesive is used as the axially low moisture permeability adhesive ad, the optical axis of the first lens 13 is likely to deviate, but by using the acrylic adhesive as the axially low moisture permeability adhesive ad, the deviation of the optical axis of the first lens 13 can be prevented.

[0043] Further, in the present embodiment, the low moisture permeability adhesive ad preferably has an elastic modulus of 1 to 1000 MPa and a Tg of 40°C to 60°C. The elastic modulus indicates the ease of moisture passage (moisture permeability) of the low moisture permeability adhesive ad. When the elastic modulus is less than 1 MPa, the flexibility of the low moisture permeability adhesive ad increases, making it easier for moisture to pass through. On the other hand, when it exceeds 1000 MPa, the low moisture permeability adhesive ad becomes too hard, making the first lens 13 prone to breakage. Therefore, it is preferable that the elastic modulus of the low moisture permeability adhesive ad is 1 to 1000 MPa. Tg is the glass transition temperature of the low moisture permeability adhesive. When Tg exceeds 60°C, the low moisture permeability adhesive becomes too hard, making the first lens prone to breakage. On the other hand, when it is less than 40°C, the low moisture permeability adhesive becomes too soft, making it easier for moisture to pass through (the waterproof property deteriorates). Therefore, it is preferable that Tg is 40°C to 60°C.

[0044] In this embodiment, the first lens 13 is adhesively fixed to the second lens 14 by the radial low moisture permeability adhesive ad, and the first lens 13 is adhesively fixed to the lens barrel 12 by the axial low moisture permeability adhesive ad to ensure waterproofing. However, if waterproofing can be ensured only by the radial low moisture permeability adhesive ad, the axial low moisture permeability adhesive ad may not be used.

[0045] As described above, according to this embodiment, the first lens 13 located on the object side and the second lens 14 adjacent to the first lens 13 on the image side are adhesively waterproofed by the low moisture permeability adhesive ad so that the space k between the lenses is sealed from the outside. Therefore, even in a high humidity environment, it is difficult for moisture to enter the space k between the lenses without using an O-ring. Therefore, even when the outside air temperature drops, fogging due to condensation on the back surface (concave surface 13c) of the first lens 13 can be prevented. Also, since no O-ring is used, deterioration of optical performance caused by the first lens 13 receiving a reaction force from the O-ring and shifting in the optical axis direction can be prevented. Also, since no O-ring is used, the number of component parts does not increase, and it does not take time to install the O-ring. In addition, since the first lens 13 and the lens barrel 12 are adhesively waterproofed with a low moisture permeability adhesive ad, it becomes difficult for moisture to enter the lens barrel from between the first lens 13 and the lens barrel 12. Therefore, fogging due to dew condensation on the back surface of the first lens 13 can be more reliably prevented.

[0046] In addition, since the outer peripheral surface of the first lens 13 and the inner peripheral surface of the lens barrel 12 are adhesively waterproofed with an axially low moisture permeability adhesive ad, moisture flowing from the object side surface of the first lens 13 to the outer peripheral surface can be more reliably waterproofed. Furthermore, since the filling portions 30, 31 filled with the low moisture permeability adhesive ad are provided to extend in the circumferential direction on either the outer peripheral surface of the first lens 13 or the inner peripheral surface of the lens barrel 12, the low moisture permeability adhesive ad for waterproofing between the outer peripheral surface of the first lens 13 and the inner peripheral surface of the lens barrel 12 can be reliably filled. Also, since the filling portions 30, 31 have bottom surfaces 30a, 31a at the lower ends, the low moisture permeability adhesive ad to be filled stops flowing down at the bottom surfaces 30a, 31a. Therefore, it is possible to prevent the low moisture permeability adhesive ad from invading into the lens barrel 12 beyond the outer peripheral surface of the first lens 13 or the inner peripheral surface of the lens barrel 12. In addition, since the first lens 13 is adhesively fixed to the lens barrel 12 with an axially low moisture permeability adhesive ad and fixed to the second lens 14 with a radially low moisture permeability adhesive ad, when an impact is applied to the lens unit 11, it becomes difficult for either one of the low moisture permeability adhesives ad to be damaged. Therefore, the responsiveness to impacts is good.

[0047] In addition, since the low moisture permeability adhesive ad has an elastic modulus of 1 to 1000 MPa and a Tg of 40°C to 60°C, the first lens 13 and the second lens 14, which are located closest to the object side, and the first lens 13 and the lens barrel 12 can be more reliably waterproofed with the low moisture permeability adhesive ad, and breakage of the first lens 13 can be prevented.

[0048] (Second Embodiment) FIG. 3 shows a lens unit 11 according to a second embodiment of the present invention. The difference between this lens unit 11 and the lens unit 11 of the first embodiment shown in FIG. 1 is that the end face 13a on the image side of the first lens 13 and the surface intersecting the axial direction of the lens barrel 12 are adhesively waterproofed with a low moisture permeability adhesive a. Therefore, this point will be described below, and the same components as those in the first embodiment may be denoted by the same reference numerals and their description may be omitted.

[0049] As shown in FIG. 3(a), a cylindrical inner wall 12b is provided on the object side inside the lens barrel 12. The tip face (upper end face) of this inner wall 12b is a flat face 12c orthogonal (intersecting) to the axial direction of the lens barrel 12. The flat face 12c and the outer peripheral portion of the end face 13a on the image side of the first lens 13 are adhesively waterproofed with a low moisture permeability adhesive ad (hereinafter, also referred to as a radial low moisture permeability adhesive ad). The flat face 12c faces the end face 13a on the image side of the first lens 13 and is disposed in the vicinity of the outer peripheral side of the end face 13a. Before incorporating the first lens 13 into the lens barrel 12, after applying the low moisture permeability adhesive ad to the flat face 12c, by incorporating the first lens 13 into the lens barrel 12, the end face 13a on the image side of the first lens 13 and the flat face 12c of the lens barrel 12 are adhesively waterproofed with the radial low moisture permeability adhesive ad.

[0050] In this embodiment, the axial low moisture permeability adhesive ad and the radial low moisture permeability adhesive ad (the radial low moisture permeability adhesive ad that adhesively waterproofs the flat face 12c of the lens barrel 12 and the end face 13a on the image side of the first lens 13) are provided separately, but they may be provided continuously so as to form an L-shaped cross section. When an acrylic-based adhesive is used as the radial low moisture permeability adhesive ad, it is preferable to roughen the flat face 12c of the lens barrel 12 and / or the end face 13a on the image side of the first lens 13.

[0051] According to this embodiment, the same effects as those in the first embodiment can be obtained, and in addition, the following effects can be obtained. Since the end face 13a on the image side of the first lens 13 and the flat surface 12c orthogonal to the axial direction of the lens barrel 12 are adhesively waterproofed with a radially low moisture permeability adhesive ad, even if the axial low moisture permeability adhesive ad that waterproofs the space between the outer peripheral surface of the first lens 13 and the inner peripheral surface of the lens barrel 12 is damaged by an impact or the like and moisture enters the lens barrel, it is possible to surely prevent the moisture from entering the space on the back surface of the first lens. Further, since the first lens 13 is adhesively waterproofed with one axial low moisture permeability adhesive ad and two radial low moisture permeability adhesives ad, the waterproof effect and the adhesive strength are enhanced.

[0052] (Third and Fourth Embodiments) FIG. 4 is a semi-sectional view showing a lens unit according to a third embodiment of the present invention, and FIG. 5 is a semi-sectional view showing a lens unit according to a fourth embodiment of the present invention. In the above-described first and second embodiments, the case where the resin lens barrel 12 is used has been described as an example. In the third and fourth embodiments, a metal lens barrel 32 is used. Also in this metal lens barrel 32, the first lens 33, the second lens 34, the third lens 35, the fourth lens 36, and the fifth lens 37 are incorporated from the object side (upper side in FIGS. 4 and 5) in the same manner as in the resin lens barrel 12. Also, the filter 105 is adhered to the lower surface of the inner flange portion 38 with a low moisture permeability adhesive ad.

[0053] When using a metal lens barrel 32, in the third embodiment, as shown in FIG. 4(a), the first lens 33 located on the most object side and the second lens 34 adjacent to the first lens 33 on the image side are adhesively waterproofed with a low moisture permeability adhesive ad so that the space k between the lenses is sealed from the outside. That is, the end face 33a on the image side of the first lens 33 and the end face 34a on the object side of the second lens 34 are adhesively waterproofed with a radially low moisture permeability adhesive ad. Also, a filling portion 30 having a bottom surface 30a is provided on the inner peripheral surface of the lens barrel 32 so as to extend in the circumferential direction, and the filling portion 30 is filled with a low moisture permeability adhesive ad, thereby adhesively waterproofing the outer peripheral surface of the first lens 33 and the inner peripheral surface of the lens barrel 32 with an axial low moisture permeability adhesive ad.

[0054] Also, by screwing and tightening a cap (pressing member) 40 to the object side end (upper end) of the lens barrel 32, the first lens 33 is fixed in the optical axis direction to the object side end of the lens barrel 32. Note that when the outer peripheral surface of the first lens 33 can be adhesively fixed to the inner peripheral surface of the lens barrel 32 with a predetermined axial adhesive strength by an axially low moisture permeable adhesive ad, the cap 40 may not be necessary.

[0055] Also, as in the modified example shown in FIG. 4(b), the end face 33a on the image side of the first lens 33 and the flat face 32c orthogonal (intersecting) to the axial direction of the lens barrel 32 may be adhesively waterproofed with a radially low moisture permeable adhesive ad. Also in this case, when the outer peripheral surface of the first lens 33 can be adhesively fixed to the inner peripheral surface of the lens barrel 12 with a predetermined axial adhesive strength by an axially low moisture permeable adhesive ad, the cap 40 may not be necessary.

[0056] Also, in the fourth embodiment, as shown in FIG. 5(a), the first lens 33 located on the most object side and the second lens 34 adjacent to the first lens 33 on the image side are adhesively waterproofed with a low moisture permeable adhesive ad so that the space k between the lenses is sealed from the outside. That is, the end face 33a on the image side of the first lens 33 and the end face 34a on the object side of the second lens 34 are adhesively waterproofed with a radially low moisture permeable adhesive ad. Also, a filling portion 31 filled with a low moisture permeable adhesive ad may extend in the circumferential direction on the outer peripheral surface of the first lens 33. Such a filling portion 31 also has a bottom face 31a on the image side. By filling the filling portion 31 with a low moisture permeable adhesive ad, the outer peripheral surface of the first lens 33 and the inner peripheral surface of the lens barrel 32 are adhesively waterproofed with an axially low moisture permeable adhesive ad.

[0057] Also, as shown in the modified example of FIG. 5(b), the end face 33a on the image side of the first lens 33 and the flat face 32c orthogonal (intersecting) to the axial direction of the lens barrel 32 may be adhesively waterproofed with a radially low moisture permeable adhesive ad. Even in this case, if the outer peripheral surface of the first lens 33 can be adhesively fixed to the inner peripheral surface of the lens barrel 12 with a predetermined axial adhesive strength by the axially low moisture-permeable adhesive ad, the cap 40 may not be necessary.

[0058] Even in such third and fourth embodiments, the same effects as those of the first and second embodiments can be obtained.

[0059] In the first to fourth embodiments described above, the lens unit 11 including the second lens 14 adjacent to the first lens 13 on the image side and the lens unit including the second lens 34 adjacent to the first lens 33 on the image side have been described. However, instead of this, the present invention can also be applied to a lens unit including optical components such as a spacer or an optical filter adjacent to the first lenses 13 and 33 on the image side. Further, the present invention is not limited to the above-described embodiments, and can be implemented with various modifications without departing from the gist thereof. For example, in the present invention, the shapes of the lens, the lens barrel, etc. are not limited to those in the above-described embodiments. Also, within the range not departing from the gist of the present invention, a part or all of the above-described embodiments may be combined, or a part of the configuration may be omitted from one of the above-described embodiments.

Explanation of Reference Numerals

[0060] 11 Lens unit 12, 32 Lens barrel 12c, 32c Flat surface (surface intersecting the axial direction of the lens barrel) 13, 33 First lens 14, 34 Second lens 13a, 33a End face of the first lens on the image side 14a, 34a End face of the second lens on the object side 15, 16, 17, 34, 35, 36, 37 Lenses 30, 31 Filling portion ad Low moisture-permeable adhesive

Claims

1. In a lens unit including a plurality of lenses arranged along an optical axis and a lens barrel that houses and holds these plurality of lenses, the plurality of lenses include a first lens located on the most object side and a second lens adjacent to the first lens on the image side, an adhesive for waterproofing the lens space between the first lens and the second lens is filled between the first lens and the second lens and between the first lens and the lens barrel, the adhesive is provided as an axially waterproof adhesive filled in a groove-shaped filling portion provided on the inner peripheral surface of the lens barrel that fits with the outer peripheral surface of the first lens between the object-side end portion of the outer peripheral surface of the first lens and the inner peripheral surface of the lens barrel, a first radially waterproof adhesive filled between the image-side end surface of the first lens and the object-side end surface of the second lens adjacent to the lens space, and a second radially waterproof adhesive that adheres the radially outer peripheral side of the image-side end surface of the first lens and a surface intersecting the axial direction formed by the cylindrical inner wall of the lens barrel, respectively, and is provided separately. A lens unit characterized by that.

2. The lens unit according to claim 1, wherein the adhesive has an elastic modulus of 1 to 1000 MPa and a Tg of 40°C to 60°C.

3. A camera module comprising the lens unit according to claim 1 or 2.

Images