Lens units and camera modules

Abstract

To provide a lens unit capable of preventing outgas generated from an adhesive from adhering to an image-side optical surface of a first lens, 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 an adhesive ad, and gas absorbent 41 for absorbing outgas generated from the adhesive ad is provided between the adhesive ad and an image-side optical surface 13c of the first lens 13, thereby allowing the gas absorbent 41 to absorb the outgas generated from the adhesive ad so as to prevent the outgas from adhering to the image-side optical surface 13c of the first lens 13.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a lens unit and a camera module that can constitute an on-board 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 (vehicle-mounted camera) captures the scenery outside the vehicle and the captured image is displayed on a monitor mounted inside the vehicle. The lens unit of the vehicle-mounted 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 fogging of the lens. In this lens unit, four lenses are arranged in the lens barrel along the optical axis direction. On the object side, sealing is achieved by disposing an elastic seal member such as an O-ring between the first lens closest to the object and the inner peripheral 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 an adhesive. In this way, the object side seal and the image side seal ensure airtightness inside the lens barrel, and fogging of the lens is prevented. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2008-233512 A Summary of the Invention [Problem to be solved by the invention]

[0005] As mentioned above, even if the first lens is waterproofed by an O-ring (elastic sealing member), there is still a possibility that moisture may get into the inter-lens space between the first lens and the second lens adjacent to it on the image side. In this case, the back surface of the first lens located on the object side is likely to become fogged up due to condensation. One possible solution is to use an adhesive to waterproof the first lens, which is located closest to the object, and the second lens, which is adjacent to this first lens on the image side. However, in this case, if there are uncured areas of the adhesive before the adhesive has completely hardened during the manufacture of the lens unit, or even after the lens unit has been manufactured, there is a risk that the adhesive will outgas, such as siloxane gas or organic gas, and that the outgas will adhere to the image-side optical surface of the first lens, degrading the optical performance.

[0006] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a lens unit and a camera module that can prevent outgassing from an adhesive from adhering to the image-side optical surface of the first lens. [Means for solving the problem]

[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 the plurality of lenses, a first lens located closest to the object side among the plurality of lenses and an optical component adjacent to the first lens on the image side and / or the lens barrel are bonded with an adhesive; A gas adsorbent that adsorbs outgassed from the adhesive is provided between the adhesive and the image-side optical surface of the first lens.

[0008] Here, since the first lens may be adjacent to a second lens on the image side, or adjacent to a spacer that maintains the distance between the lenses in the optical axis direction, an optical filter, etc., the "optical components" are intended to include the second lens, the spacer, and the optical filter.

[0009] Examples of the adhesive include, but are not limited to, low moisture permeable adhesives such as acrylic adhesives, epoxy adhesives, and olefin adhesives.

[0010] In the present invention, a gas adsorbent that adsorbs outgassed from the adhesive is provided between the adhesive and the image-side optical surface of the first lens, so that most of the outgassed from the adhesive is adsorbed by the gas adsorbent, thereby making it possible to prevent the outgas from adhering to the image-side optical surface of the first lens or the object-side optical surface of the second lens that faces the image-side optical surface.

[0011] In the above-described configuration of the present invention, an annular groove may be provided along a circumferential direction on an object-side end face of the optical component and / or an image-side end face of the first lens, and the gas adsorbent may be accommodated and fixed in the annular groove.

[0012] According to this configuration, since the gas adsorbent is contained and fixed in the annular groove, the gas adsorbent can be reliably positioned and provided between the adhesive and the image-side optical surface of the first lens.

[0013] In the above-mentioned configuration of the present invention, the gas adsorbent may comprise powdered activated carbon and a porous resin having a large number of pores, and the powdered activated carbon may be held in the large number of pores of the porous resin.

[0014] Here, as the porous resin, a porous polyurethane resin is preferably used, but the present invention is not limited thereto.

[0015] According to this configuration, by containing and fixing in the annular groove a gas adsorbent comprising powdered activated carbon held in a large number of pores in a porous resin, it is possible to prevent the powdered activated carbon from protruding from the annular groove and entering the image-side optical surface of the first lens.

[0016] In the above-mentioned configuration of the present invention, the gas adsorbent may be granular activated carbon, and the granular activated carbon may be contained and fixed in the annular groove.

[0017] Here, the average particle size of the granular activated carbon is about 0.01 to 0.1 mm, and it is preferable that the maximum particle size is slightly larger than the groove width so that the granular activated carbon fits into the annular groove and does not fall out of the annular groove, and that the portion of the maximum particle size fits into the annular groove.

[0018] According to this configuration, the granular activated carbon is contained and fixed in the annular groove, so that the activated carbon can be prevented from protruding from the annular groove and entering the image-side optical surface of the first lens.

[0019] In the above-mentioned configuration of the present invention, an adhesive may be provided in the annular groove, and the granular activated carbon may be adhered to the adhesive.

[0020] Here, it is preferable that the adhesive applied to the annular groove not be applied to the entirety of the granular activated carbon, but to a part of the lower portion, for example.

[0021] According to this configuration, the granular activated carbon is adhered to the adhesive provided in the annular groove, so that the granular activated carbon can be firmly fixed to the annular groove.

[0022] A camera module according to the present invention includes the lens unit. According to this configuration, the effects of the lens unit described above can be obtained in the camera module. Effect of the Invention

[0023] According to the present invention, most of the outgas generated from the adhesive is adsorbed by the gas adsorbent, so that it is possible to prevent the outgas from adhering to the image-side optical surface of the first lens. [Brief description of the drawings]

[0024] [Figure 1] FIG. 1 is a schematic cross-sectional view of a lens unit according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic cross-sectional view of the camera module according to the first embodiment. [Diagram 3]FIG. 11 is a schematic cross-sectional view of a main portion of a second embodiment of the present invention. [Figure 4] FIG. [Diagram 5] FIG. 11 is a schematic cross-sectional view of a main portion of a second embodiment of the present invention. [Figure 6] FIG. [Figure 7] FIG. 11 is a schematic cross-sectional view of a main portion of a third embodiment of the present invention. [Figure 8] FIG. 10 is a schematic cross-sectional view of a lens unit according to a fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. It should be noted that the lens unit of this embodiment described below is intended particularly for a camera module such as an in-vehicle camera, and is fixedly installed, for example, on the outer surface of a vehicle, with wiring being pulled into the vehicle and connected to a display or other device. The lens unit of the present embodiment described below is particularly intended for use as a camera module for an in-vehicle camera, and is fixedly installed on the outer surface of a vehicle, with wiring leading into the vehicle and connected to a display or other device. In addition, hatching is omitted for the lenses in all the drawings.

[0026] (First embodiment) 1 shows a lens unit 11 according to a first embodiment of the present invention. As shown in the figure, the lens unit 11 of this embodiment includes a cylindrical lens barrel 12 made of, for example, resin, and a plurality of lenses arranged in a stepped inner storage space S of the lens barrel 12, for example, five lenses consisting of a first lens 13, a second lens 14, a third lens 15, a fourth lens 16, and a fifth lens 17 from the object side (the upper side in FIG. 1), and two diaphragm members 22a and 22b.

[0027] Of the two diaphragm members 22a and 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 and 22b are "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 and light rays that cause aberrations. An in-vehicle camera equipped with such a lens unit 11 includes the lens unit 11, a substrate having an image sensor (not shown), and an installation member (not shown) that installs the substrate on a vehicle such as an automobile.

[0028] The lenses 13, 14, 15, 16, and 17 are assembled and held in the inner storage space S of the lens barrel 12, and are stacked and arranged with their optical axes aligned. 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 and is a spherical glass lens having a convex surface on the object side and a concave surface (optical surface) 13c on 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 (optical surface) 14c on 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; when the first and second lenses 13 and 14 are made of resin, the difference between the linear expansion coefficients of the first lens 13 and the second lens 14 is, for example, 40×10 -6 / K(m) or more).

[0029] In this embodiment, the number of lenses, the materials of the lenses and the 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 is not necessary. The surfaces of these lenses 13, 14, 15, 16, and 17 may be provided with an anti-reflection film, a hydrophilic film, a water-repellent film, or the like, as necessary. Furthermore, in this embodiment, unlike the prior art, no elastic seal member such as an O-ring is provided inside the lens barrel.

[0030] Furthermore, with lens group L assembled and housed within inner 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 located 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 where crimping portion 23 is pressed is formed as flat portion 13b that is cut obliquely into a plane.

[0031] 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. By this inner flange portion 24 and crimped portion 23, multiple lenses 13, 14, 15, 16, and 17 and diaphragm members 22a and 22b constituting lens group L within lens barrel 12 are held and fixed in the optical axis direction.

[0032] The inner diameter of the lens barrel 12 gradually decreases from the object side to the image surface side. Correspondingly, the outer diameters of the lenses 13, 14, 15, 16, and 17 gradually decrease from the object side to the image surface side. Basically, the outer diameters of the lenses 13, 14, 15, 16, and 17 are approximately equal to the inner diameters of the portions of the lens barrel 12 where the lenses 13, 14, 15, 16, and 17 are supported. An outer flange portion 25 is provided on the outer circumferential surface of the lens barrel 12 in the shape of a brim and is used when installing the lens barrel 12 on a vehicle-mounted camera.

[0033] 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.

[0034] 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 seal member 303 and a package sensor (imaging element) 304.

[0035] Upper case 301 is a member that exposes the object side end of lens unit 11 and covers other portions. Mount 302 is disposed inside upper case 301, and has female threads 302a that screw into 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 circumferential surface of barrel 12 of lens unit 11, and is a member that maintains airtightness inside upper case 301.

[0036] Package sensor 304 is disposed inside mount 302, and is disposed at a position where it receives an image of an 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 is a component of 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.

[0037] In the lens unit 11 and camera module 300 configured as above, 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 waterproofed with a low moisture permeable adhesive ad (hereinafter also referred to as a radial 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 a space formed between a concave surface 13c formed on the image side end face of the first lens 13 and a concave surface 14c formed on the object side end face of the second lens 14. 1, 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 the end face 13a and the outer peripheral surface of the end face 14a, and the first lens 13 and the second lens 14 are bonded and waterproofed by the low-moisture-permeable adhesive ad so that the space k between the lenses is sealed from the outside.

[0038] In addition, 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 deteriorate when UV light is irradiated onto the hydrophilic film 13m, resulting in deterioration of optical performance. However, in this embodiment and the second to fourth embodiments described later, the first lens 13 and the second lens 14 are adhered and waterproofed by a low moisture permeable adhesive ad so that the space k between the lenses is sealed against the outside, and the space k is also dustproof, so that foreign matter does not adhere to the hydrophilic film 13m, and deterioration of the hydrophilic film 13m can be prevented.

[0039] In addition, the outer peripheral surface of the first lens 13 and the inner peripheral surface of the lens barrel 12 are bonded and waterproofed by a low moisture permeable adhesive ad (hereinafter, sometimes referred to as an axially low moisture permeable adhesive ad). In this embodiment, a filling section 30 filled with the low moisture permeable adhesive ad is provided extending in the circumferential direction on the inner peripheral surface of the lens barrel 12. The filling section 30 is formed by cutting out the inner peripheral surface of the lens barrel 12 into a ring groove having a rectangular cross section, extends in the axial direction of the lens barrel 12, and has a bottom surface 30a at the end on the image side. Such a filling section 30 is formed on the inner peripheral surface of the lens barrel 12 before the crimping section 23 is crimped (indicated by a 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 in the axial direction by the low moisture permeable adhesive ad. In addition, even when the first lens 13 and the second lens 14 are waterproofed by radially bonding them with 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 from above (from the object side) on the second lens 14. When filling the filling section 30 with the low-moisture permeable adhesive ad, the low-moisture permeable adhesive ad is filled from the upper end opening of the filling section 30, but since the filling section 30 has a bottom surface 30a at its lower end, the low-moisture permeable adhesive ad stops flowing down at the bottom surface 30a. Therefore, it is possible to prevent the low-moisture permeable adhesive ad from going beyond the outer peripheral surface of the first lens 13 or the inner peripheral surface of the lens barrel 12 and entering the lens barrel 12.

[0040] In addition, in this embodiment, only one filling section 30 is formed, but by forming multiple filling sections 30 at a predetermined interval in the axial direction of the lens barrel 12, multiple axially low moisture permeable adhesives ad can be provided at a predetermined interval 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 by the axially low moisture permeable adhesive ad, the crimped portion 23 may be omitted.

[0041] 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 more. 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 incorporate the first lens 13 into the lens barrel 12 while ensuring waterproofing between its outer peripheral surface and the inner peripheral surface of the lens barrel 12.

[0042] An epoxy-based adhesive has a higher adhesive strength than an acrylic-based adhesive, but is inferior in impact resistance, and therefore there is a risk that the epoxy-based adhesive will peel off when a thermal shock test is performed on the lens unit 11. For this reason, it is preferable to use an acrylic-based adhesive, which has better impact resistance than an epoxy-based adhesive, 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 the lens barrel 12 and / or the outer peripheral surface of the first lens 13 by a roughening means such as sandblasting. Also, when an acrylic adhesive is used as the radially low moisture permeable 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 a roughening means 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. Furthermore, 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.

[0043] 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; however, roughening the surfaces improves the adhesion of the low moisture permeable adhesive ad, so it is preferable to do so. In addition, since the epoxy adhesive has a higher adhesive strength than the acrylic adhesive, the epoxy adhesive may be used as the radially low moisture permeable adhesive ad, which has the advantage of preventing the optical axis of the first lens 13 from shifting. Furthermore, since an epoxy-based adhesive is harder than an acrylic-based adhesive, when an epoxy-based 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-based adhesive as the axially low-moisture-permeable adhesive ad, it is possible to prevent the optical axis of the first lens 13 from becoming misaligned.

[0044] 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 the low moisture permeable adhesive ad (moisture permeability), and if the elastic modulus is less than 1 MPa, the low moisture permeable adhesive ad becomes highly flexible and easily transmits moisture, whereas if it exceeds 1000 MP, the low moisture permeable adhesive ad becomes too hard and the first lens 13 becomes easily damaged. For this reason, it is preferable that the elastic modulus of the low moisture permeable adhesive ad is 1 to 1000 MPa. Tg is the glass transition temperature of the low moisture permeable adhesive, and if the Tg exceeds 60°C, the low moisture permeable adhesive becomes too hard and the first lens becomes easily damaged, whereas if the Tg is less than 40°C, the low moisture permeable adhesive becomes too soft and easily transmits moisture (resulting in reduced waterproofing). For this reason, it is preferable to set the Tg to 40°C to 60°C.

[0045] In this embodiment, waterproofing is ensured by adhesively fixing the first lens 13 to the second lens 14 with the radial low-moisture-permeable adhesive ad, and by adhesively fixing the first lens 13 to the lens barrel 12 with the axial low-moisture-permeable adhesive ad. However, if waterproofing can be ensured with only the radial low-moisture-permeable adhesive ad, it is not necessary to use the axial low-moisture-permeable adhesive ad.

[0046] In addition, in this embodiment, a gas adsorbent 41 that adsorbs outgassing from the radial low-moisture permeable adhesive ad and the axial low-moisture permeable adhesive ad is provided between the radial low-moisture permeable adhesive ad and the optical surface 13c of the first lens 13. 1 to 4, an annular groove 40 is provided in the circumferential direction on the object-side end face 14a of the second lens 14. The annular groove 40 is formed in a rectangular cross section and opens to the end face 14a. The annular groove 40 is disposed adjacent to the outer periphery of a concave surface (optical surface) 14c provided on the object side of the second lens 14 on the end face 14a.

[0047] A gas adsorbent 41 is accommodated and fixed in the annular groove 40. The gas adsorbent 41 includes powdered activated carbon 42 and a porous resin 43 having a large number of holes, and the powdered activated carbon 42 is held in the large number of holes in the porous resin 43. The gas adsorbent 41 thus configured is formed into a ring shape and has a rectangular cross section, and the gas adsorbent 41 is accommodated and fixed in the annular groove 40. In this embodiment, the porous resin 43 is a porous polyurethane resin, but is not limited thereto. The upper end of the gas adsorbent 41 protrudes into the gap between the end face 13a of the first lens 13 and the end face 14a of the second lens 14. The above-mentioned radially low moisture permeable adhesive ad is filled in this gap at a position radially outwardly spaced a predetermined distance from the annular groove 40, radially outwardly of the gas adsorbent 41. The powdered activated carbon 42 is held in a large number of pores in the porous resin 43 and is open to the outside, so that the outgas generated from the radially low moisture permeable adhesive ad is adsorbed by the powdered activated carbon 42.

[0048] In this embodiment, an annular groove 40 is formed in the end face 14a of the second lens 14. In addition to or instead of this, an annular groove may be formed in the end face 13a of the first lens 13, and a gas adsorbent 41 may be contained and fixed in the annular groove.

[0049] As described above, according to this embodiment, the gas adsorbent 41 that adsorbs outgassing is provided between the radially low-moisture-permeable adhesive ad and the image-side optical surface 13c of the first lens 13, so that most of the outgas generated from the radially low-moisture-permeable adhesive ad and the axially low-moisture-permeable adhesive ad is adsorbed by the gas adsorbent 41. Therefore, it is possible to prevent the outgas from adhering to the image-side optical surface 13c of the first lens 13 and the object-side optical surface 14c of the second lens 14 that faces the optical surface 13c.

[0050] Furthermore, an annular groove 40 is provided along the circumferential direction on the object-side end face 14a of the second lens 14, and a gas adsorbent 41 is contained and fixed in the annular groove 40, so that the gas adsorbent 41 can be reliably positioned and provided between the radial low-moisture-permeable adhesive ad and the image-side optical surface 13c of the first lens 13. Furthermore, gas adsorbent 41 comprises powdered activated carbon 42 and porous resin 43 having a large number of holes, and powdered activated carbon 42 is held in the large number of holes in porous resin 43. Therefore, by containing and fixing gas adsorbent 41 in annular groove 40, it is possible to prevent powdered activated carbon 42 from protruding from annular groove 40 and invading the image-side optical surface 13c of first lens 13.

[0051] In addition, 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 so that the space between the lenses k is sealed from the outside, so moisture is unlikely to enter the space between the lenses k even in a high humidity environment without using an O-ring. Therefore, even if 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 caused by first lens 13 receiving a reaction force from the O-ring and being misaligned 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 take the time to attach the O-rings. In addition, since the first lens 13 and the lens barrel 12 are waterproofed by the 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.

[0052] In addition, since the outer peripheral surface of the first lens 13 and the inner peripheral surface of the lens barrel 12 are waterproofed with the axially low moisture permeable adhesive ad, it is possible to more reliably prevent moisture from flowing from the object-side surface of the first lens 13 to the outer peripheral surface. Furthermore, since the filling section 30 filled with the low-moisture permeable adhesive ad is provided extending in the circumferential direction on the outer peripheral surface of the first lens 13, the low-moisture permeable adhesive ad that waterproofs the gap between the outer peripheral surface of the first lens 13 and the inner peripheral surface of the lens barrel 12 can be reliably filled. Furthermore, since the filling section 30 has a bottom surface 30a at the lower end, the low-moisture permeable adhesive ad that is filled stops flowing down at the bottom surface 30a. Therefore, it is possible to prevent the low-moisture permeable adhesive ad from going beyond the outer peripheral surface of the first lens 13 or the inner peripheral surface of the lens barrel 12 and entering the lens barrel 12. Furthermore, since the first lens 13 is adhered and fixed to the lens barrel 12 by the axial low-moisture-permeable adhesive ad, and is fixed to the second lens 14 by the radial low-moisture-permeable adhesive ad, when an impact is applied to the lens unit 11, either one of the low-moisture-permeable adhesives ad is unlikely to break, resulting in good shock resistance. Furthermore, since the low-moisture permeable 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 second lens 14, which are located closest to the object, as well as 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.

[0053] Second Embodiment 5 and 6 show a lens unit according to a second embodiment of the present invention, where FIG. 5 is a cross-sectional view of the main part and FIG. 6 is a schematic semi-planar cross-sectional view of the main part. The present embodiment differs from the first embodiment in that the activated carbon contained and fixed in the annular groove 40 is granular activated carbon. This point will be explained below, and the same components as those in the first embodiment will be given the same symbols and their explanations may be omitted.

[0054] 5 and 6, similarly to the first embodiment, an annular groove 40 is provided along the circumferential direction on the object-side end face 14a of the second lens 14. Granular activated carbon 45 is accommodated and fixed in the annular groove 40. The average particle size of the granular activated carbon 45 is about 0.01 to 0.1 mm, and the maximum particle size is slightly larger than the groove width of the annular groove 40 so that the granular activated carbon 45 fits into the annular groove 40 and does not fall out of the annular groove 40, and the portion of the maximum particle size fits into the annular groove 40. 5, an annular groove 46 may be provided adjacent to the annular groove 40 on the end face 14a of the second lens 14, opening on the end face 14a. The annular groove 46 is disposed adjacent to the annular groove 40 on the radially outer side, and a radially low moisture permeable adhesive ad is filled on the radially outer side of the annular groove 46. By providing the annular groove 46 in this manner, even if the radially low moisture permeable adhesive ad flows radially inward, it accumulates in the annular groove 46, so that the radially low moisture permeable adhesive ad covers the granular activated carbon 45, and it is possible to prevent the granular activated carbon 45 from losing or decreasing its adsorption power for adsorbing outgas.

[0055] According to this embodiment, in addition to being able to obtain the same effects as in the first embodiment, since the granular activated carbon 45 is contained and fixed in the annular groove 40, it is possible to obtain the effect that the granular activated carbon 45 can be prevented from protruding from the annular groove 40 and entering the image-side optical surface 13c of the first lens 13. Moreover, unlike the first embodiment, the gas adsorbent 41 is granular activated carbon 45, and the granular activated carbon 45 is directly contained and fixed in the annular groove 40. Therefore, the configuration of the gas adsorbent 41 is simpler than that of the gas adsorbent 41 in the first embodiment, and the cost can be reduced accordingly.

[0056] (Third embodiment) FIG. 7 is a cross-sectional view of a main part of a lens unit according to a third embodiment of the present invention. The present embodiment differs from the second embodiment in that adhesive 47 is provided in the annular groove 40, and so this point will be explained below. The same components as in the second embodiment will be given the same symbols and their explanations may be omitted.

[0057] 7, similarly to the second embodiment, an annular groove 40 is provided along the circumferential direction on the object-side end face 14a of the second lens 14, and an adhesive 47 is provided in this annular groove 40. This adhesive 47 is filled below half of the annular groove 40, and the adhesive 47 is adhered to the lower part (part) of the granular activated carbon 45 fitted in the annular groove 40, and the granular activated carbon 45 is exposed above the upper surface (surface) of the adhesive 47. The adhesive 47 may be a low moisture permeable adhesive, but any ordinary adhesive will do.

[0058] According to this embodiment, in addition to being able to obtain the same effects as those of the second embodiment, since the granular activated carbon 45 is adhered to the adhesive 47 provided in the annular groove 40, it is possible to obtain the effect that the granular activated carbon 45 can be firmly fixed to the annular groove 40.

[0059] (Fourth embodiment) In the above-described first to third embodiments, a lens unit having a structure in which the lens barrel 12 and the outer peripheral surface of the first lens 13 are not sealed by a sealing member such as an O-ring has been used as an example. However, the present invention can also be applied to a lens unit having a structure in which the lens barrel 12 and the outer peripheral surface of the first lens 13 are sealed by a sealing member 26 such as an O-ring, as shown in the fourth embodiment of FIG. 8. In FIG. 8, the same components as those in the lens unit of the first embodiment shown in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted.

[0060] 8, an O-ring 26 serving as a seal member is interposed between first lens 13, which is located closest to the object side, and lens barrel 12 to prevent water and dust from entering lens group L inside lens barrel 12. Also, a cylindrical inner wall 12b is provided on the object side inside lens barrel 12, and a groove 18 is formed between this inner wall 12b and outer wall 12c. An annular body 27 is provided in groove 18, and O-ring 26 is in close contact with this annular body 27. Furthermore, the adhesive for bonding the first lens 13 and the second lens 14 may be a low moisture permeable adhesive, but a normal adhesive 48 will suffice.

[0061] In the fourth embodiment, as in the first to third embodiments, 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 bonded with an adhesive 48, and a gas adsorbent 41 that adsorbs outgassing from the adhesive 48 is provided between the adhesive 48 and the image-side optical surface 13c of the first lens 13, so that the same effect as in the first embodiment can be obtained.

[0062] Moreover, in FIG. 8, instead of the gas adsorbent 41 including powdered activated carbon and a porous resin having a large number of holes, the gas adsorbent 41 may be granular activated carbon, and this granular activated carbon may be accommodated and fixed in the annular groove 40, as in the second and third embodiments.

[0063] In the above-described first to fourth embodiments, the lens unit 11 including the second lens 14 adjacent to the first lens 13 on the image side has been described. However, the present invention can also be applied to a lens unit including an optical component such as a spacer or an optical filter adjacent to the first lens 13 on the image side instead. In addition, the present invention is not limited to the above-mentioned embodiment, and can be modified in various ways without departing from the scope of the present invention. For example, the shapes of the lenses, lens barrels, etc., in the present invention are not limited to the above-mentioned embodiment. In addition, the above-mentioned embodiments may be combined in part or in whole, or a part of the configuration may be omitted from one of the above-mentioned embodiments, without departing from the scope of the present invention. [Explanation of symbols]

[0064] 11 Lens unit 12 Telescope tube 13 First lens 14 Second lens (optical component) 13a: image side end surface of the first lens 14a: Object side end surface of second lens 15,16,17 Lenses 40 Annular groove 41 Gas adsorbents 42 Powdered activated carbon 43 Porous Resin 45 Granular activated carbon 47 Adhesive 48 Adhesive ad Low moisture permeability adhesive (adhesive) 300 Camera Module

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 first lens located closest to the object side among the plurality of lenses, and a second lens adjacent to the first lens on the image side and / or the lens barrel are bonded together with an adhesive; a gas adsorbent that adsorbs outgassed from the adhesive is provided between the adhesive and the image-side optical surface of the first lens; the gas adsorbent adsorbs outgassing from the adhesive toward an inter-lens space between the image-side optical surface of the first lens and the object-side optical surface of the second lens, between the image-side end face of the first lens and the object-side end face of the second lens.

2. 2. The lens unit according to claim 1, characterized in that an annular groove is provided along a circumferential direction on an object-side end face of the second lens and / or an image-side end face of the first lens, and the gas adsorbent is accommodated and fixed in the annular groove.

3. 3. The lens unit according to claim 2, wherein the gas adsorbent comprises powdered activated carbon and a porous resin having a large number of pores, the powdered activated carbon being held in the large number of pores of the porous resin.

4. 3. The lens unit according to claim 2, wherein the gas adsorbent is granular activated carbon, the granular activated carbon being accommodated and fixed in the annular groove.

5. 5. The lens unit according to claim 4, wherein an adhesive is provided in the annular groove, and the granular activated carbon is adhesively fixed to the adhesive.

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

Images