Lens unit and camera module

Abstract

To provide a lens unit that can prevent fogging on a rear face of a first lens by securely waterproofing a lens space between the first lens and a second lens without using an O-ring, and can prevent deterioration of optical performance, and a camera module.SOLUTION: Of a plurality of lenses, a first lens 13 located on the most object side, and a second lens 14 adjacent to the first lens 13 on an image side are adhered to each other with a low-moisture-permeability adhesive ad and waterproofed, and thereby fogging on a rear face of the first lens can be prevented by securely waterproofing a space between the first lens and a lens barrel without using an O-ring, and deterioration of optical performance can be prevented.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 technology]

[0002] There is a known technology in which a camera mounted on a vehicle (on-board camera) captures images of scenery outside the vehicle and the captured images are displayed on a monitor or the like mounted inside the vehicle. The lens unit of an on-board camera is required to have strength, waterproofing, chemical resistance, high-temperature durability, etc., because the side facing the subject (object side) is exposed to the outside of the vehicle. In addition, it is necessary to prevent the lens from fogging up due to temperature changes.

[0003] Patent Document 1 discloses a lens unit that ensures an airtight state inside the lens barrel to prevent lens fogging. In this lens unit, four lenses are arranged side by side inside the lens barrel along the optical axis. On the object side, sealing is achieved by disposing an elastic sealing member such as an O-ring between the first lens closest to the object and the inner circumferential surface of the lens barrel. On the image side (image sensor side), sealing is achieved by attaching an optical filter to the lens barrel via adhesive. In this way, the object side seal and the image side seal ensure airtightness inside the lens barrel, preventing lens fogging. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-233512 Summary of the Invention [Problem to be solved by the invention]

[0005] As mentioned above, if the first lens is waterproofed by an O-ring (elastic sealing member), and the O-ring becomes improperly attached because it gets caught in the lens barrel, moisture can easily get into the space between the outermost lens (first lens) and the second lens adjacent to this first lens on the image side in a high-humidity environment, and if the outside temperature drops, the back surface of the outermost lens on the object side can easily become cloudy due to condensation. Furthermore, since an O-ring (elastic sealing member) is placed in a compressed state between the first lens and the inner surface of the lens barrel, the first lens receives a reaction force due to the elastic restoring force of the O-ring, and as a result, if the first lens shifts in the optical axis direction, the optical performance deteriorates. Furthermore, since an O-ring must be incorporated into the lens barrel, the number of parts increases accordingly, and the installation of the O-ring is also time-consuming.

[0006] The present invention has been made in consideration of the above circumstances, and aims to provide a lens unit and a camera module that can reliably waterproof the lens space between the first lens and the second lens without using an O-ring, prevent fogging on the back surface of the first lens, and prevent deterioration of optical performance. [Means for solving the problem]

[0007] In order to solve the above-mentioned 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 the plurality of lenses, Among the plurality of lenses, the first lens located closest to the object and the optical component adjacent to this first lens on the image side are waterproofed and bonded with a low moisture permeable adhesive.

[0008] Examples of low moisture permeable adhesives include acrylic adhesives, epoxy adhesives, and olefin adhesives. In addition, the first lens may be adjacent to a second lens on the image side, or may be adjacent to a spacer that maintains the distance between the lenses in the optical axis direction, an optical filter, etc., so the ``optical components'' mentioned above include the second lens, the spacer, and the optical filter.

[0009] In the present invention, the first lens element closest to the object and the optical component adjacent to this first lens element on the image side are waterproofed with a low-moisture-permeable adhesive, so moisture is less likely to enter the inter-lens space between the first lens element and the second lens element, even in high-humidity environments, without the need for an O-ring. Therefore, fogging due to condensation on the back surface of the first lens element can be prevented, even when the outside temperature is low. Furthermore, since no O-ring is used, it is possible to prevent the first lens from receiving a reaction force from the O-ring and being displaced in the optical axis direction, thereby preventing deterioration of optical performance. Furthermore, since no O-rings are used, the number of parts does not increase and there is no need to bother with installing O-rings.

[0010] In the above-described configuration of the present invention, the first lens and the lens barrel may be waterproofed and bonded together with a low moisture-permeable adhesive.

[0011] With this configuration, the first lens and the lens barrel are waterproofed and bonded together with a low moisture-permeable adhesive, making it difficult for moisture to enter the lens barrel from between the first lens and the lens barrel, thereby more reliably preventing fogging due to condensation on the back surface of the first lens.

[0012] In the above-described configuration of the present invention, the outer peripheral surface of the first lens and the inner peripheral surface of the lens barrel may be waterproofed and bonded together with the low moisture-permeable 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 of the low moisture permeable adhesive.

[0014] With this configuration, the outer peripheral surface of the first lens and the inner peripheral surface of the lens barrel are waterproofed with a low moisture-permeable adhesive, thereby more reliably preventing moisture from flowing from the object-side surface of the first lens to the outer peripheral surface.

[0015] In the above-described configuration of the present invention, the image-side end face of the first lens and a surface intersecting the axial direction of the lens barrel may be waterproofed and bonded together with the low-moisture-permeable adhesive. The intersecting plane is preferably a plane perpendicular to the axial direction of the lens barrel, but may be inclined relative to the axial direction.

[0016] With this configuration, the image-side end face of the first lens and the surface that intersects with the axial direction of the lens barrel are waterproofed with a low-moisture-permeable adhesive, so that even if the low-moisture-permeable adhesive that waterproofs the space between the outer surface of the first lens and the inner surface of the lens barrel is damaged by an impact or the like and moisture enters the lens barrel, the moisture can be reliably prevented from entering the space on the back surface of the first lens. Furthermore, since the low-moisture-permeable adhesive is present both in the axial direction of the lens barrel and in the direction intersecting the axial direction, when an impact is applied to the lens unit, one of the low-moisture-permeable adhesives is less likely to break, resulting in good shock resistance.

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

[0018] The elastic modulus is an index of the moisture permeability of the low moisture permeable adhesive, and if the elastic modulus is less than 1 MPa, the low moisture permeable adhesive becomes too flexible and moisture permeable, while if it exceeds 1000 MPa, the low moisture permeable adhesive becomes too hard and is prone to breakage when subjected to impact. For this reason, it is preferable that the elastic modulus of the low moisture permeable adhesive be 1 to 1000 MPa. Tg is the glass transition temperature of the low-moisture-permeable adhesive, and if Tg exceeds 60°C, the low-moisture-permeable adhesive becomes too hard and the first lens becomes more susceptible to breakage, while if it is below 40°C, the low-moisture-permeable adhesive becomes too soft and more susceptible to moisture permeation (resulting in reduced waterproofing). For this reason, it is preferable that Tg be set to 40°C to 60°C.

[0019] With this configuration, the first lens and the second lens located closest to the object side can be more reliably waterproofed with the low moisture permeable adhesive, and damage to the first lens can be prevented.

[0020] A camera module according to the present invention includes the lens unit. With this configuration, the effects of the lens unit described above can be obtained with the camera module. [Effects of the Invention]

[0021] According to the present invention, it is possible to reliably waterproof the first lens, which is located closest to the object, without using an O-ring between the lens barrel and the first lens, thereby preventing fogging on the back surface of the first lens and preventing deterioration of optical performance. [Brief explanation of the drawings]

[0022] [Figure 1] 1A and 1B show a first embodiment of the present invention, in which FIG. 1A is a schematic cross-sectional view of a lens unit, and FIG. 1B is a cross-sectional view of a main part of a modified lens unit. [Figure 2] FIG. 2 is a schematic cross-sectional view of the camera module according to the first embodiment. [Figure 3] 10A and 10B show a second embodiment of the present invention, in which FIG. 10A is a schematic cross-sectional view of a lens unit, and FIG. 10B is a cross-sectional view of a main part of a modified lens unit. [Figure 4] 10A and 10B show a third embodiment of the present invention, in which FIG. 10A is a schematic half cross-sectional view of a lens unit, and FIG. 10B is a schematic half cross-sectional view of a modified lens unit. [Figure 5] 10A and 10B show a fourth embodiment of the present invention, in which FIG. 10A is a schematic half cross-sectional view of a lens unit, and FIG. 10B is a schematic half cross-sectional view of a modified lens unit. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The lens unit of this embodiment described below is intended particularly for use in a camera module such as an in-vehicle camera, and is fixedly installed on the exterior surface of the vehicle, with wiring leading into the vehicle and connected to a display or other device. The lens unit of this embodiment described below is particularly intended for use in a camera module such as an in-vehicle camera, and is fixedly installed on the exterior surface of the vehicle, with wiring leading into the vehicle and connected to a display or other device. Furthermore, hatching of the lens is omitted in all figures.

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

[0025] Of the two diaphragm members 22a, 22b, the first diaphragm member 22a from the object side is disposed between the second lens 14 and the third lens 15. The second diaphragm member 22b from the object side is disposed between the third lens 15 and the fourth lens 16. The diaphragm members 22a, 22b are either "aperture diaphragms" that limit the amount of transmitted light and determine the F-number, which is an index of brightness, or "light-blocking diaphragms" that block light rays that cause ghosts or light rays that cause aberrations. An in-vehicle camera equipped with such a lens unit 11 includes the lens unit 11, a board having an image sensor (not shown), and an installation member (not shown) for installing the board on a vehicle such as an automobile.

[0026] The multiple lenses 13, 14, 15, 16, and 17 incorporated and housed within the internal housing space S of the lens barrel 12 are stacked and arranged with their optical axes aligned, and the lenses 13, 14, 15, 16, and 17 are arranged along a single optical axis O to form a lens group L used for imaging. In this case, the first lens 13, which is located closest to the object side of the lens group L, is a spherical glass lens having a convex surface facing the object side and a concave surface 13c facing the image side, and the second lens 14, which is adjacent to the first lens 13 on the image side, is a resin lens having a concave surface 14c facing the object side. The other lenses 15, 16, and 17, including the second lens 14, are resin lenses, but are not limited to this (for example, the first lens 13 may be a resin lens; if the first and second lenses 13 and 14 are made of resin, the difference in linear expansion coefficient between the first lens 13 and the second lens 14 may be, for example, 40×10). -6 / K(m) or more).

[0027] In this embodiment, the number of lenses, the materials of the lenses and lens barrel, etc. can be set arbitrarily depending on the application, etc. In this embodiment, the fourth and fifth lenses 16 and 17 located on the image side are cemented lenses, but this does not have to be the case. The surfaces of these lenses 13, 14, 15, 16, and 17 may be coated with an anti-reflection film, a hydrophilic film, a water-repellent film, or the like, as needed. Furthermore, in this embodiment, unlike the prior art, no elastic seal member such as an O-ring is provided inside the lens barrel.

[0028] Furthermore, with lens group L incorporated and housed within internal housing space S of lens barrel 12, crimping portion 23 at the object-side end (upper end in FIG. 1) is thermally crimped radially inward, thereby fixing first lens 13, which is positioned closest to the object side of lens group L, to the object-side end of lens barrel 12 in the optical axis direction by crimping portion 23. In this case, to ensure stable crimping, the portion of glass lens 13 to which crimping portion 23 is pressed is formed as flat portion 13b, which is cut diagonally in a planar shape.

[0029] Furthermore, an inner flange portion 24 having an opening with a diameter smaller than that of fifth lens 17 is provided at the end (the lower end in FIG. 1) of lens barrel 12 on the image side. This inner flange portion 24 and crimped portion 23 hold and fix the multiple lenses 13, 14, 15, 16, and 17 and diaphragm members 22a and 22b that make up lens group L inside lens barrel 12 in the optical axis direction.

[0030] The inner diameter of lens barrel 12 gradually decreases from the object side to the image plane side. Correspondingly, the outer diameters of lenses 13, 14, 15, 16, and 17 gradually decrease from the object side to the image plane side. Basically, the outer diameters of lenses 13, 14, 15, 16, and 17 are approximately equal to the inner diameters of the portions of lens barrel 12 that support lenses 13, 14, 15, 16, and 17. An outer flange portion 25 is provided on the outer peripheral surface of the lens barrel 12 in the shape of a brim, and is used when the lens barrel 12 is installed on an in-vehicle camera.

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

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

[0033] Upper case 301 is a member that exposes the object-side end of lens unit 11 and covers the other portions. Mount 302 is disposed inside upper case 301, and has female threads 302a that mesh with male threads 11a of lens unit 11. Sealing member 303 is a member that is interposed between the inner surface of upper case 301 and the outer peripheral surface of barrel 12 of lens unit 11, and is a member that maintains airtightness inside upper case 301.

[0034] Package sensor 304 is disposed inside mount 302 and is positioned to receive the image of the object formed by lens unit 11. Package sensor 304 also includes a CCD, CMOS, or the like, and converts the light that is collected and reaches it through lens unit 11 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. The filter 105 is adhered to the lower surface of the inner flange portion 24 with a low moisture permeable adhesive ad.

[0035] In the lens unit 11 and camera module 300 configured as described above, the first lens 13 located closest to the object and the second lens 14 adjacent to the first lens 13 on the image side are waterproofed with a low-moisture-permeable adhesive ad (hereinafter also referred to as a radially low-moisture-permeable adhesive ad) so that the space between the lenses k is sealed from the outside. The space between the lenses k is the space formed between the concave surface 13c formed on the image-side end face of the first lens 13 and the concave surface 14c formed on the object-side end face of the second lens 14. 1(a), the image-side end face 13a of the first lens 13 is formed into a circular annular plane, and the object-side end face 14a of the second lens 14 is formed into a circular annular plane. A low-moisture-permeable adhesive ad is interposed between the inner peripheral surface of end face 13a and end face 14a, and the first lens 13 and the second lens 14 are adhered and waterproofed by the low-moisture-permeable adhesive ad so that the space k between the lenses is sealed from the outside.

[0036] Furthermore, 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, if foreign matter adheres to the hydrophilic film 13m, the hydrophilic film 13m may be deteriorated when irradiated with UV light, resulting in a deterioration in optical performance. However, in this embodiment and the second to fourth embodiments described below, the first lens 13 and the second lens 14 are adhered and waterproofed with a low-moisture-permeable adhesive ad so that the space k between the lenses is sealed from the outside and is also dustproof. This prevents foreign matter from adhering to the hydrophilic film 13m, thereby preventing deterioration of the hydrophilic film 13m.

[0037] Furthermore, the outer peripheral surface of first lens 13 and the inner peripheral surface of barrel 12 are bonded and waterproofed with a low-moisture-permeable adhesive ad (hereinafter also referred to as the axially low-moisture-permeable adhesive ad). In this embodiment, a filling section 30 filled with the low-moisture-permeable adhesive ad is provided on the inner peripheral surface of barrel 12, extending in the circumferential direction. Filling section 30 is formed by cutting out the inner peripheral surface of barrel 12 into the shape of a ring groove with a rectangular cross section, and extends in the axial direction of barrel 12, having a bottom surface 30a at the end on the image side. Such filling section 30 is formed on the inner peripheral surface of barrel 12 before crimping section 23 (indicated by the two-dot chain line in FIG. 1). Then, before crimping the crimped portion 23, the filling portion 30 is filled with the low-moisture-permeable adhesive ad, and after filling, the crimped portion 23 is crimped. As a result, the outer peripheral surface of the first lens 13 and the inner peripheral surface of the lens barrel 12 are bonded and waterproofed together by the axial low-moisture-permeable adhesive ad. Furthermore, even when the first lens 13 and the second lens 14 are waterproofed by radially bonding them together with a low-moisture-permeable adhesive ad, the low-moisture-permeable adhesive ad is applied to at least one of the end face 13a of the first lens 13 and the end face 14a of the second lens 14 before crimping the crimping portion 23, and then the first lens 13 is assembled into the lens barrel 12 by overlapping it on top of the second lens 14 (from the object side). When filling portion 30 with low-moisture permeable adhesive ad, the low-moisture permeable adhesive ad is filled from the upper opening of filling portion 30, but because filling portion 30 has bottom surface 30a at its lower end, the filled low-moisture permeable adhesive ad stops flowing down at bottom surface 30a. Therefore, it is possible to prevent the low-moisture permeable adhesive ad from going over the outer peripheral surface of first lens 13 or the inner peripheral surface of barrel 12 and entering barrel 12.

[0038] In addition, in this embodiment, only one filling section 30 is formed, but by forming multiple filling sections 30 at predetermined intervals in the axial direction of the lens barrel 12, multiple axially low moisture-permeable adhesives ad can be provided at predetermined intervals in the axial direction. If the outer peripheral surface of the first lens 13 can be bonded and fixed to the inner peripheral surface of the lens barrel 12 with a predetermined axial adhesive strength using the axially low moisture permeable adhesive ad, the crimped portion 23 may be omitted.

[0039] 2(b), a filling portion 31 filled with an axially low moisture-permeable adhesive ad may be provided on the outer peripheral surface of the first lens 13, extending in the circumferential direction. Such a filling portion 31 also has a bottom surface 31a on the image side. Note that in this modification, there is no crimping portion 23, and the first lens 13 is fixed to the lens barrel 12 by the axially low moisture-permeable adhesive ad; however, a crimping portion 23 may be provided, and the first lens 13 may be fixed by this crimping portion 23.

[0040] Examples of the low-moisture-permeable adhesive include acrylic adhesives, epoxy adhesives, and olefin adhesives, and the viscosity of these adhesives is preferably 10 Pa·S or higher. If the viscosity is less than 10 Pa·S, the axially low-moisture-permeable adhesive ad will tend to drip downward (toward the image side), making it difficult to assemble first lens 13 into the lens barrel 12 while maintaining waterproofing 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, and therefore there is a risk that the epoxy adhesive will peel off when a thermal shock test is performed on lens unit 11. For this reason, it is preferable to use acrylic adhesives, which have better impact resistance than epoxy adhesives, but there is a risk that the adhesive strength will be insufficient. For this reason, when an acrylic adhesive is used as the axially low-moisture-permeable adhesive ad, it is preferable to roughen the inner peripheral surface of lens barrel 12 and / or the outer peripheral surface of first lens 13 by a roughening method such as sandblasting. Also, when an acrylic adhesive is used as the radially low-moisture-permeable adhesive ad, it is preferable to roughen end face 13a of first lens 13 and / or end face 14a of second lens 14 by a roughening method such as sandblasting. In such a case, it is preferable to set the root mean square surface roughness Rq to about 0.01 μm to 200 μm. When an acrylic adhesive is used as the low moisture permeable adhesive ad, it is preferable to make the adhesive area large in order to ensure adhesive strength.

[0042] A metal lens barrel 12 has better adhesive adhesion than a resin lens barrel 12, so in the case of a metal lens barrel 12, it may not be necessary to roughen the inner surface or flat surface 12c of the lens barrel 12, but roughening it is preferable as this improves the adhesion of the low-moisture-permeable adhesive ad. Furthermore, since epoxy adhesives have a higher adhesive strength than acrylic adhesives, epoxy adhesives may be used as the radially low-moisture-permeable adhesive ad, which has the advantage of preventing misalignment of the optical axis of first lens 13. Furthermore, since epoxy adhesives are harder than acrylic adhesives, when an epoxy adhesive is used as the axially low moisture-permeable adhesive ad, it is easy for the optical axis of the first lens 13 to become misaligned. However, by using an acrylic adhesive as the axially low moisture-permeable adhesive ad, it is possible to prevent misalignment of the optical axis of the first lens 13.

[0043] In this embodiment, the low moisture permeable 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 with which moisture can pass through (moisture permeability) of the low-moisture-permeable adhesive ad, and if the elastic modulus is less than 1 MPa, the low-moisture-permeable adhesive ad becomes too flexible and more moisture-permeable, whereas if it exceeds 1000 MPa, the low-moisture-permeable adhesive ad becomes too hard and more susceptible to damage to first lens 13. For this reason, the elastic modulus of the low-moisture-permeable adhesive ad is preferably set to 1 to 1000 MPa. Tg is the glass transition temperature of the low-moisture-permeable adhesive, and if Tg exceeds 60°C, the low-moisture-permeable adhesive becomes too hard and the first lens becomes more susceptible to breakage, while if it is below 40°C, the low-moisture-permeable adhesive becomes too soft and more susceptible to moisture permeation (resulting in reduced waterproofing). For this reason, it is preferable that Tg be set to 40°C to 60°C.

[0044] In this embodiment, waterproofing is ensured by adhesively fixing the first lens 13 to the second lens 14 with a radially low-moisture-permeable adhesive ad, and by adhesively fixing the first lens 13 to the lens barrel 12 with an axially low-moisture-permeable adhesive ad, but if waterproofing can be ensured with only the radially low-moisture-permeable adhesive ad, the axially low-moisture-permeable adhesive ad does not need to be used.

[0045] As described above, according to this embodiment, the first lens 13 located closest to the object and the second lens 14 adjacent to this first lens 13 on the image side are waterproofed with a low-moisture-permeable adhesive ad so that the space k between the lenses is sealed from the outside, so moisture is less likely to enter the space k between the lenses even in a high-humidity environment, even without using an O-ring. Therefore, even when the outside temperature is low, fogging due to condensation on the back surface (concave surface 13c) of the first lens 13 can be prevented. Furthermore, since no O-ring is used, it is possible to prevent deterioration of optical performance due to the first lens 13 receiving a reaction force from the O-ring and being displaced in the optical axis direction. Furthermore, since no O-rings are used, the number of parts does not increase and there is no need to bother with installing the O-rings. Furthermore, since the first lens 13 and the lens barrel 12 are adhered and waterproofed with a low moisture permeable adhesive ad, moisture is less likely to enter the lens barrel from between the first lens 13 and the lens barrel 12, and therefore fogging due to condensation on the back surface of the first lens 13 can be more reliably prevented.

[0046] Furthermore, the outer peripheral surface of the first lens 13 and the inner peripheral surface of the lens barrel 12 are waterproofed with an axially low moisture permeable adhesive ad, so that moisture flowing from the object side surface of the first lens 13 to the outer peripheral surface can be more reliably prevented. Furthermore, filling sections 30, 31 filled with low-moisture permeable adhesive ad are provided extending circumferentially on either the outer peripheral surface of first lens 13 or the inner peripheral surface of lens barrel 12, so that the low-moisture permeable adhesive ad can be reliably filled to waterproof the gap between the outer peripheral surface of first lens 13 and the inner peripheral surface of lens barrel 12. Furthermore, filling sections 30, 31 have bottom surfaces 30a, 31a at their lower ends, so that the filled low-moisture permeable adhesive ad stops flowing down at bottom surfaces 30a, 31a. This prevents the low-moisture permeable adhesive ad from going beyond the outer peripheral surface of first lens 13 or the inner peripheral surface of lens barrel 12 and entering the lens barrel 12. Furthermore, since the first lens 13 is adhered and fixed to the lens barrel 12 with an axially low-moisture-permeable adhesive ad and is fixed to the second lens 14 with a radially low-moisture-permeable adhesive ad, when an impact is applied to the lens unit 11, either of the low-moisture-permeable adhesives ad is unlikely to break, resulting in good shock resistance.

[0047] Furthermore, the low-moisture-permeable adhesive ad has an elastic modulus of 1 to 1000 MPa and a Tg of 40°C to 60°C, so that the first lens 13 and second lens 14, which are located closest to the object, and the first lens 13 and lens barrel 12 can each be more reliably waterproofed by the low-moisture-permeable adhesive ad, and damage to the first lens 13 can be prevented.

[0048] (Second embodiment) Figure 3 shows a lens unit 11 according to a second embodiment of the present invention. This lens unit 11 differs from the lens unit 11 of the first embodiment shown in Figure 1 in that the image-side end face 13a of the first lens 13 and the surface intersecting the axial direction of the lens barrel 12 are waterproofed with a low-moisture-permeable adhesive a, and therefore this point will be described below, and the same components as those in the first embodiment will be assigned the same reference numerals and their description may be omitted.

[0049] As shown in Figure 3(a), a cylindrical inner wall 12b is provided on the object side inside the lens barrel 12, and the tip surface (upper end surface) of this inner wall 12b is a flat surface 12c that is perpendicular to (intersects with) the axial direction of the lens barrel 12, and this flat surface 12c and the outer periphery of the image-side end surface 13a of the first lens 13 are bonded and waterproofed with a low-moisture-permeable adhesive ad (hereinafter sometimes referred to as radial low-moisture-permeable adhesive ad). Flat surface 12c faces image-side end face 13a of first lens 13 and is located near the outer periphery of end face 13a. Before incorporating first lens 13 into lens barrel 12, a low-moisture-permeable adhesive ad is applied to flat surface 12c, and then first lens 13 is incorporated into lens barrel 12, whereby image-side end face 13a of first lens 13 and flat surface 12c of lens barrel 12 are adhered and waterproofed by the radially low-moisture-permeable adhesive ad.

[0050] In addition, in this embodiment, the axially low-moisture-permeable adhesive ad and the radially low-moisture-permeable adhesive ad (the radially low-moisture-permeable adhesive ad that waterproofs the flat surface 12c of the lens barrel 12 and the image-side end face 13a of the first lens 13) are provided at a distance from each other, but they may also be provided continuously so as to form an L-shaped cross section. Furthermore, when an acrylic adhesive is used as the radially low moisture permeable adhesive ad, it is preferable to roughen the flat surface 12c of the lens barrel 12 and / or the image-side end surface 13a of the first lens 13.

[0051] According to this embodiment, in addition to the same effects as those of the first embodiment, the following effects can be obtained. The image-side end face 13a of the first lens 13 and the flat surface 12c perpendicular to the axial direction of the lens barrel 12 are adhered and waterproofed by a radially low-moisture-permeable adhesive ad, so that even if the axially low-moisture-permeable adhesive ad that waterproofs the space between the outer surface of the first lens 13 and the inner surface of the lens barrel 12 is damaged by an impact or the like and moisture enters the lens barrel, the moisture can be reliably prevented from entering the space on the back surface of the first lens. Furthermore, the first lens 13 is adhered and waterproofed with one axially low-moisture-permeable adhesive ad and two radially low-moisture-permeable adhesives ad, thereby improving the waterproof effect and adhesive strength.

[0052] (Third and Fourth Embodiments) FIG. 4 is a half cross-sectional view showing a lens unit according to a third embodiment of the present invention, and FIG. 5 is a half cross-sectional view showing a lens unit according to a fourth embodiment of the present invention. While the first and second embodiments described above have been described using an example in which a resin lens barrel 12 is used, the third and fourth embodiments use a metal lens barrel 32. As with the resin lens barrel 12, this metal lens barrel 32 also incorporates, from the object side (the upper side in FIGS. 4 and 5), a first lens 33, a second lens 34, a third lens 35, a fourth lens 36, and a fifth lens 37. The filter 105 is also adhered to the lower surface of the inner flange portion 38 with a low moisture permeable adhesive ad.

[0053] 4(a), in the third embodiment, when a metal lens barrel 32 is used, a first lens 33 located closest to the object and a second lens 34 adjacent to the first lens 33 on the image side are waterproofed with a low-moisture-permeable adhesive ad so that the space k between the lenses is sealed from the outside. In other words, an end face 33a on the image side of the first lens 33 and an end face 34a on the object side of the second lens 34 are waterproofed with a radial low-moisture-permeable adhesive ad. In addition, a filling section 30 having a bottom surface 30a is provided on the inner surface of the lens barrel 32, extending in the circumferential direction, and this filling section 30 is filled with a low-moisture-permeable adhesive ad, thereby bonding and waterproofing the outer surface of the first lens 33 and the inner surface of the lens barrel 32 with the axially low-moisture-permeable adhesive ad.

[0054] Furthermore, by screwing and tightening a cap (pressing member) 40 onto the object side end (upper end) of the lens barrel 32, the first lens 33 is fixed to the object side end of the lens barrel 32 in the optical axis direction. If the outer peripheral surface of the first lens 33 can be bonded and fixed to the inner peripheral surface of the lens barrel 32 with a predetermined axial adhesive strength using the axially low moisture permeable adhesive ad, the cap 40 may be omitted.

[0055] Furthermore, as in the modified example shown in Figure 4(b), the image-side end face 33a of the first lens 33 and the flat surface 32c that is perpendicular to (intersects with) the axial direction of the lens barrel 32 may be waterproofed by bonding them together with a radially low-moisture-permeable adhesive ad. Even in this case, if the outer peripheral surface of the first lens 33 can be bonded and fixed to the inner peripheral surface of the lens barrel 12 with a predetermined axial adhesive strength using the axially low moisture permeable adhesive ad, the cap 40 may be omitted.

[0056] 5(a), in the fourth embodiment, a first lens 33 located closest to the object and a second lens 34 adjacent to the first lens 33 on the image side are waterproofed with a low-moisture-permeable adhesive ad so that the space k between the lenses is sealed from the outside. That is, an end face 33a on the image side of the first lens 33 and an end face 34a on the object side of the second lens 34 are waterproofed with a radially low-moisture-permeable adhesive ad. Furthermore, a filling section 31 filled with a low-moisture-permeable adhesive ad may extend circumferentially on the outer peripheral surface of the first lens 33. Such a filling section 31 also has a bottom surface 31a on the image side. By filling this filling section 31 with the 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 bonded and waterproofed by the axial low-moisture-permeable adhesive ad.

[0057] Furthermore, as shown in a modified example in Figure 5(b), the image-side end face 33a of the first lens 33 and the flat surface 32c that is perpendicular to (intersects with) the axial direction of the lens barrel 32 may be waterproofed and bonded together with a radially low moisture-permeable adhesive ad. Even in this case, if the outer peripheral surface of the first lens 33 can be bonded and fixed to the inner peripheral surface of the lens barrel 12 with a predetermined axial adhesive strength using the axially low moisture permeable adhesive ad, the cap 40 may be omitted.

[0058] In the third and fourth embodiments, the same effects as in the first and second embodiments can be obtained.

[0059] In the first to fourth embodiments described above, the lens unit 11 includes the second lens 14 adjacent to the first lens 13 on the image side, and the lens unit includes the second lens 34 adjacent to the first lens 33 on the image side. However, the present invention can also be applied to a lens unit that includes optical components such as a spacer or an optical filter adjacent to the first lenses 13 and 33 on the image side. Furthermore, the present invention is not limited to the above-described embodiments and can be implemented in various modifications without departing from the spirit of the present invention. For example, in the present invention, the shapes of the lenses, lens barrels, etc. are not limited to the above-described embodiments. Furthermore, within the spirit of the present invention, some or all of the above-described embodiments may be combined, or part of the configuration of one of the above-described embodiments may be omitted. [Explanation of symbols]

[0060] 11 Lens unit 12,32 telescope 12c, 32c Flat surface (surface intersecting the axial direction of the telescope tube) 13,33 First lens 14,34 Second lens 13a, 33a: image-side end surface of the first lens 14a, 34a: Object-side end surface of second lens 15, 16, 17, 34, 35, 36, 37 Lenses 30,31 Filling section ad Low moisture permeability adhesive

Claims

1. A lens unit including a plurality of lenses arranged along an optical axis and a lens barrel that houses and holds the plurality of lenses, A lens unit characterized in that a first lens, which is located closest to the object side among the plurality of lenses, and an optical component adjacent to the first lens on the image side are waterproofed and bonded with a low moisture-permeable adhesive.

2. 2. The lens unit according to claim 1, wherein the first lens and the lens barrel are waterproofed by bonding them together with a low moisture-permeable adhesive.

3. 3. The lens unit according to claim 2, wherein the outer peripheral surface of the first lens and the inner peripheral surface of the lens barrel are waterproofed by the low moisture-permeable adhesive.

4. 4. The lens unit according to claim 2, wherein the image-side end face of the first lens and the surface intersecting the axial direction of the lens barrel are waterproofed by the low-moisture-permeable adhesive.

5. 5. The lens unit according to claim 1, wherein the low moisture permeable adhesive has a modulus of elasticity of 1 to 1000 MPa and a Tg of 40 to 60°C.

6. A camera module comprising the lens unit according to any one of claims 1 to 5.

Images