Lens unit and camera module

Abstract

To provide a lens unit and a camera module capable of keeping airtight the inside of an inter-lens space between a lens located closest to an object and a lens adjacent thereto by an adhesion medium and suppressing intrusion of water vapor into the inter-lens space, and also capable of preventing a lens cracking phenomenon caused by the adhesion medium.SOLUTION: In a lens unit 11, first and second lenses 13 and 14 have ring-like opposite surfaces 13a and 14a extending in a radial direction of the lenses by facing each other in an optical axis direction, the respective opposite surfaces 13a and 14a are radially outside an edge P of an opposite region R, and an adhesion medium 40 is applied to the outer surface(s) of the first lens 13 and / or the second lens 14 so that the inside of an inter-lens space S1 between the first lens 13 and the second lens 14 is sealed from the outside.SELECTED DRAWING: Figure 2

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

[0003] In particular, in a lens unit for an in-vehicle camera, when at least a part of the lens unit is installed outside the vehicle, an O-ring 104 is inserted between the first lens 100, which is positioned closest to the object side of the lens group L, and the lens barrel 102 in a state where the lens group L is assembled and housed and held in the inner housing space S of the lens barrel 102, as shown in Fig. 8, for waterproofing and dustproofing, so as to prevent water and dust from entering the lens group L inside the lens barrel 102. In this case, for example, an outer peripheral side surface 100a of the first lens 100 is provided with a stepped reduced diameter portion 100b whose diameter is reduced at the image side portion of the lens 100, and an O-ring 104 is attached to this reduced diameter portion 100b, and the O-ring 104 is compressed in the radial direction between the outer peripheral side surface 100a of the first lens 100 and the inner peripheral surface 102a of the lens barrel 102, so that the object side end of the lens barrel 102 is sealed.

[0004] Furthermore, with the lens group L assembled and housed within the inner housing space S of the lens barrel 102, the crimping portion 123 at the object side end (the upper end in FIG. 8) is crimped radially inward, thereby fixing the first lens 100 to the object side end of the lens barrel 102 by this crimping portion 123. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2013-231993 A Summary of the Invention [Problem to be solved by the invention]

[0006] However, even if waterproofing is implemented using O-ring 104 as described above, moisture (water vapor) can enter the lens unit through various routes. Therefore, when the difference between the outside air temperature and the temperature inside the lens unit becomes large, the water vapor inside the lens unit condenses and condensation occurs on the lens surface. In particular, condensation is likely to occur on back surface 100c of first lens 100 in inter-lens space S1 between first lens 100 and adjacent second lens 101, which is most affected by the temperature difference with the outside.

[0007] Factors that cause a large difference between the outside air temperature and the temperature inside the lens unit include the temperature inside the lens unit rising in winter when the outside air is cold, the temperature inside the lens unit rising due to heat transmitted from an image sensor (image pickup element) that is always powered for receiving light focused through the lens unit and converting it into an electrical signal, or the first lens 100 being cooled when the surface 100d of the first lens 100 is exposed to the outside air, rain, etc. when the temperature inside the lens unit is high due to heat from the image sensor or the surrounding environment (for example, a vehicle engine).

[0008] Examples of paths that allow water vapor to enter the lens unit include a path that passes from the gap between the crimped portion 123 of the lens barrel 102 and the first lens 100 through a part of the periphery of the O-ring 104 and the gap between the first lens 100 and the lens barrel 102 and / or the second lens 101 to the inter-lens space S1, or a path via the moisture-permeable resin that forms the lens barrel 102. Furthermore, the image sensor (imaging element) arranged on the image side of the lens unit rises to about 100 degrees during operation, and at that time, there is also a path in which moisture contained in the substrate on which the image sensor is mounted turns into water vapor and reaches the inter-lens space S1.

[0009] In any case, if water vapor enters the lens unit through such a route and a temperature difference occurs between the outside air and the inside of the lens unit due to the factors described above, condensation will occur in the inter-lens space S1, particularly on the back surface 100c of the first lens 100, causing the captured image to become blurred and making it impossible to obtain the desired resolution (deteriorating visibility). Therefore, it is necessary to further ensure the airtightness of the lens unit and suppress the intrusion of water vapor into the inter-lens space S1.

[0010] Therefore, for example, it is possible to keep the space between the lenses airtight by bonding the opposing surfaces 100e, 101a of the first lens 100 and the second lens 101 together with an adhesive medium. However, in such a case, depending on the hardness of the adhesive medium, there is a risk that the lenses may crack under certain circumstances. In particular, in a combination of lenses with different linear expansion coefficients, such as when the first lens 100 is made of glass and the second lens 101 is made of resin, if the adhesive medium is a hard adhesive that is difficult to permeate water, such as an epoxy adhesive (for example, the Shore hardness is about D80), the lenses 100 and 101 can be firmly bonded together due to the high hardness of the adhesive, but the adhesive may peel off from the glass first lens 100 due to the radial relative displacement between the lenses 100 and 101 caused by the difference in the amount of expansion and contraction of the lenses when the temperature changes due to the difference in the linear expansion coefficients between the lenses 100 and 101, and the stress acting on the first lens 100 may cause cracks on the surface of the first lens 100. In particular, such a cracking phenomenon is likely to occur on the radial inner side of the opposing region between the lenses 100 and 101, where stress concentration is likely to occur due to the shape of the lenses and the bonding form between the lenses. Moreover, when an intermediate spacer is interposed between the first lens 100 and the second lens 101, such a problem can also occur between the first lens 100 made of glass and the intermediate spacer made of resin.

[0011] The present invention has been made in consideration of the above-mentioned circumstances, and has an object to provide a lens unit and camera module that can keep the inter-lens space between the lens positioned closest to the object and the adjacent lens airtight using an adhesive medium to suppress the intrusion of water vapor into the inter-lens space, while also preventing the lens from cracking due to the adhesive medium. [Means for solving the problem]

[0012] In order to solve the above problems, the present invention provides a lens unit having a lens group including a plurality of lenses arranged along an optical axis, and a cylindrical lens barrel having an inner storage space for storing and holding the lens group, the lens group includes a first lens located closest to the object side, and an optical element adjacent to the first lens on the image side thereof; The first and second optical elements have annular opposing surfaces extending radially of the lenses facing each other in the optical axis direction, and an adhesive medium is applied to the outer surface of the first lens and / or the optical element radially outward of the radially outer edge of the opposing area where these opposing surfaces face each other so that the inter-lens space between the first lens and the second lens is sealed from the outside.

[0013] The inventors have found through various experiments that the main cause of the lens cracking phenomenon described above is the application of a hard adhesive medium (adhesive) over the entire facing area of ​​the facing surfaces of the first and second lenses facing each other. When the first lens is made of glass and the second lens is made of resin, and the adhesive medium is an adhesive having a high hardness, for example, Shore hardness D70 or more, including an epoxy adhesive, as shown in Figure 1, it has been found that the cracking phenomenon of the first lens 13 described above can be avoided by preventing the adhesive medium 40 from being applied to a range exceeding 50% of the thickness T of the annular facing area R of the facing surfaces 13a, 14a of the first and second lenses 13, 14 facing each other from the inner circumference of the annular ring (in this specification, the difference between the outer diameter and the inner diameter of the annular ring). In other words, the cracking phenomenon of the first lens 13 described above can be prevented as long as the adhesive medium 40 is applied only within a range of 50% of the thickness of the annular facing region R from the outer periphery. Therefore, in the above-mentioned configuration of the present invention, the adhesive medium is applied to the outer surface of the first lens and / or the second lens (optical element) so that the inter-lens space (S1; see FIG. 1) between the first lens and the second lens is sealed against the outside, radially outward from the radially outer edge of the facing region where the facing surfaces of the first and second lenses face each other. Here, the facing region of the facing surfaces of the lenses refers to a region where the distance between the facing surfaces in the optical axis direction is 500 μm or less. The above also applies to the space between the first lens made of glass and the intermediate spacer made of resin (optical element) when an intermediate spacer is interposed between the first lens and the second lens.

[0014] This form of adhesive medium application seals the inter-lens space between the first lens and the second lens from the outside, so that even in a high humidity environment, the intrusion of water vapor into the inter-lens space, where condensation is most likely to occur, and even the intrusion of water vapor from the image side into the lens unit are suppressed (improving airtightness), reducing the amount of water vapor in the inter-lens space and suppressing condensation on the lens surfaces, in particular condensation on the image-side surface of the first lens (rear surface 13c; see Figure 1).In addition, it is possible to prevent the adhesive medium from being applied to an area exceeding 50% of the thickness of the annular facing region of the opposing surfaces of the opposing first and second lenses, which are opposed to each other, from the inner circumference of the annular facing region, thereby preventing cracking of the first lens due to the adhesive medium.

[0015] 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. Effect of the Invention

[0016] According to the present invention, an adhesive medium is applied to the outer surface of the first lens and / or the optical element radially outward of the radially outer edge of the opposing region where the opposing surfaces of the first lens and the optical element face each other, so that the inter-lens space between the first lens and the second lens is sealed from the outside.Therefore, the inter-lens space between the first lens and the second lens is kept airtight by the adhesive medium, preventing the intrusion of water vapor into the inter-lens space and also preventing the lens cracking phenomenon associated with the adhesive medium. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a schematic diagram of a lens pair for explaining the concept of the present invention. [Diagram 2] 1 is a schematic half-sectional view of a lens unit according to a first embodiment of the present invention. [Diagram 3] 3 is a schematic cross-sectional view of a camera module having the lens unit of FIG. 2. [Figure 4]FIG. 11 is a schematic half-sectional view of a lens unit according to a second embodiment of the present invention. [Diagram 5] 1 shows a lens unit according to a third embodiment of the present invention, where (a) is a cross section perpendicular to the optical axis direction at the location where the second lens is positioned before the adhesive medium is applied, (b) is a cross section perpendicular to the optical axis direction at the location where the second lens is positioned after the adhesive medium is applied, and (c) is a schematic half-cross section along the optical axis direction of the lens unit. [Figure 6] FIG. 11 is a schematic half-sectional view of a lens unit according to a fourth embodiment of the present invention. [Figure 7] FIG. 13 is a schematic half-sectional view of a lens unit according to a fifth embodiment of the present invention. [Figure 8] FIG. 1 is a schematic cross-sectional view showing an example of a conventional lens unit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The lens unit of the present embodiment described below is particularly intended for a camera module such as 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 devices. In addition, hatching is omitted for the lenses in all the drawings.

[0019] FIG. 2 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 resin, 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, and two diaphragm members 22a and 22b. Of the two diaphragm members 22a and 22b, the first diaphragm member 22a from the object side is arranged between the second lens 14 and the third lens 15. The second diaphragm member 22b from the object side is arranged 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 board having an image sensor (not shown), and an installation member (not shown) for installing the board on a vehicle such as an automobile.

[0020] The multiple lenses 13, 14, 15, 16, and 17 assembled and held within the inner storage 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 group of lenses L used for imaging. In this case, the first lens 13 that is positioned closest to the object and that constitutes the lens group L is a spherical glass lens that has a convex surface on the object side and a concave surface on the image side, and the other lenses 14, 15, 16, and 17 are resin lenses, but are not limited to this.

[0021] The present invention, including this embodiment, is characterized in that in the annular facing region R of the facing surfaces (annular facing surfaces extending in the radial direction of the lenses facing each other in the optical axis direction) 13a, 14a of the first and second lenses 13, 14 facing each other, the adhesive medium 40 is not applied to a range exceeding 50% of the thickness of the annulus (the difference between the outer diameter and the inner diameter of the annulus) from the inner circumference of the annulus (described later), and the number of lenses, the materials of the lenses and the lens barrel, etc. can be set arbitrarily according to the application, etc. In addition, in this embodiment, the two fourth and fifth lenses 16, 17 positioned on the image side are laminated lenses, but this is not necessary. Note that the surfaces of these lenses 13, 14, 15, 16, 17 are provided with an anti-reflection film, a hydrophilic film, a water-repellent film, etc. as necessary.

[0022] In this embodiment, an O-ring 26 is interposed between the first lens 13, which is located closest to the object side, and the lens barrel 12 as a seal member to prevent water and dust from entering the lens group L inside the lens barrel 12. In this case, a stepped reduced diameter portion 13e, the diameter of which is reduced at the image side portion of the lens 13, is provided on the outer circumferential surface 13d of the first lens 13, and an O-ring 26 is attached to this reduced diameter portion 13e, and the O-ring 26 is compressed in the radial direction between the outer circumferential surface 13d of the first lens 13 and the inner circumferential surface 12a of the lens barrel 12, thereby sealing the object side end of the lens barrel 12. The seal member interposed between the first lens 13 and the lens barrel 12 is not limited to an O-ring, and may be any shape as long as it is an annular body that can seal between the first lens 13 and the lens barrel 12.

[0023] Furthermore, with lens group L assembled and housed in 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, 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 where crimping portion 23 is pressed is formed as flat portion 13b that is cut obliquely into a plane.

[0024] 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.

[0025] The inner diameter of the lens barrel 12 is gradually reduced from the object side to the image surface side. Correspondingly, the outer diameter of the lenses 13, 14, 15, 16, 17 is gradually reduced from the object side to the image surface side. Basically, the outer diameter of each of the lenses 13, 14, 15, 16, 17 is approximately equal to the inner diameter of each of the portions of the lens barrel 12 where the lenses 13, 14, 15, 16, 17 are supported. In addition, an outer flange portion 25 is provided on the outer peripheral surface of the lens barrel 12 in the shape of a brim, which is used when the lens barrel 12 is installed in the vehicle-mounted camera.

[0026] Moreover, Fig. 3 is a schematic cross-sectional view of a camera module 300 of this embodiment having the lens unit 11 of Fig. 2. As shown in the figure, the camera module 300 is configured to include the lens unit 11 to which the filter 100 is attached.

[0027] 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.

[0028] 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 outer peripheral surface 12d of barrel 12 of lens unit 11, and is a member that maintains airtightness inside upper case 301.

[0029] 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.

[0030] The lens unit 11 and the camera module 300 configured as above are characterized in that, when the adhesive medium applied to seal the inter-lens space S1 between the first lens 13 and the second lens 14 from the outside is a hard adhesive that is difficult to transmit water, such as an epoxy adhesive (for example, the Shore hardness is about D80), in order to suppress cracks from occurring on the surface of the first lens 13, the adhesive is not actively provided in the annular facing region R between the facing surfaces 13a, 14a of the first lens 13 and the second lens 14. Here, the annular facing region R between the facing surfaces 13a, 14a of the first lens 13 and the second lens 14 refers to a region where the distance in the optical axis direction between the facing surfaces 13a, 14a of the first lens 13 and the second lens 14 is 500 μm or less, and also includes a contact region with a distance of 0. The adhesive medium 40 used in this embodiment is an epoxy adhesive (an adhesive containing 50% or more by weight of epoxy resin), but an acrylic or olefin adhesive (an acrylic adhesive is an adhesive containing 50% or more by weight of acrylic resin, and an olefin adhesive is an adhesive containing 50% or more by weight of olefin resin (a chain-like hydrocarbon having one double bond)) or a viscous (for example, gel-like) elastic material can also be used as the adhesive medium. In addition, such adhesive medium 40 is provided outside the effective diameter of the lenses 13 and 14 (a portion outside the optical surface where light does not pass).

[0031] In addition, in this embodiment, it is preferable that the adhesive medium 40 has "radial tracking ability" (flexibility sufficient to withstand radial stress applied to the adhesive interface of the lenses 13, 14 after the lenses 13, 14 expand (contract) due to temperature changes associated with the difference in linear expansion coefficients between the lenses 13, 14) that can follow the relative radial displacement between the lenses 13, 14 caused by the difference in the amount of expansion and contraction of the lenses when the temperature changes, and / or good "adhesion" (adhesion of the adhesive medium 40 to the opposing surfaces 13a, 14a of the lenses 13, 14) that prevents the adhesive interface between the lenses 13, 14 from peeling off due to the separation of the lenses 13, 14 in the optical axis O direction associated with an increase in internal pressure in the space S1 between the lenses in a high-temperature environment, or "optical axis tracking ability" that can follow the separation displacement between the lenses 13, 14 in the optical axis O direction.

[0032] The "radial conformability" required for the adhesive medium 40 can be achieved by setting the hardness of the adhesive medium 40 within the range of Shore hardness A10 to A100 (Shore A hardness 10 to 100) or Shore hardness D10 to D90 (Shore D hardness 10 to 90). In particular, more suitable results are obtained within the range of A30 to A95 or D10 to D60. In addition to or instead of setting the hardness of the adhesive medium within such a range, such "radial conformability" can also be achieved by ensuring that the adhesive medium has a thickness of a predetermined value or more. As a means for ensuring that the adhesive medium 40 has a thickness of a predetermined value or more (ensuring the adhesive medium 40's movement allowance along the radial direction), for example, fillers are included in the adhesive medium 40 and the maximum length of these fillers is set to 5 to 500 μm. Depending on the orientation of the filler in the adhesive medium, if the filler extends toward the optical axis O direction in the adhesive medium 40, the thickness of the adhesive medium 40 (dimension in the optical axis O direction) can be determined by the length of the extending filler.

[0033] In this embodiment using such adhesive medium 40, the adhesive medium 40 (in this embodiment, an epoxy adhesive with a Shore hardness of about D80) is applied over the outer surface (bottom surface; image side surface) of the first lens 13 and the outer surface (outer peripheral side surface facing the inner surface of the lens barrel 12) of the second lens 14 so that the space between the lenses S1 is sealed against the outside, radially outward from the radially outer edge P of the facing region R where the facing surfaces 13a, 14a of the first lens 13 made of glass and the second lens 14 made of resin face each other (including the abutting state). In this case, the adhesive medium 40 extends continuously over the radially outer outer surface portion 13h of the surface facing the image side of the first lens 13 that does not abut or face the facing surface 14a of the second lens 14, and the outer surface portion 14h that is adjacent to the outer surface portion 13h and is the outer peripheral side surface of the second lens 14 that faces the inner surface of the lens barrel 12 (L-shaped application form).

[0034] In such a coating form of the adhesive medium 40, the adhesive medium 40 may penetrate slightly into the annular opposing region R during the coating process due to surface tension, but the adhesive medium 40 does not penetrate into a range that exceeds 50% of the thickness of the annular ring (the difference between the outer diameter and the inner diameter of the annular ring) even partially from the outer periphery of the annular ring, so that it is possible to prevent the adhesive medium 40 from acting on the first lens 13 with a large stress during temperature changes, which would cause the first lens 13 to crack. Furthermore, the first lens 13 and the second lens 14 coated with the adhesive medium 40 in this manner are assembled into an integrated unit with the adhesive medium 40 and then incorporated into the lens barrel 12. Unitizing the lenses 13 and 14 in this manner has the advantage that an airtightness test (a test to confirm a sealed state) in the space S1 between the lenses can be performed on the unit alone.

[0035] 4 shows a lens unit 11A according to a second embodiment of the present invention. As shown in the figure, in the lens unit 11A according to this embodiment, similarly to the first embodiment, an adhesive medium 40 is applied over the outer peripheral side surface of the first lens 13 and the outer peripheral side surface of the second lens 14 so that the space between the lenses S1 is sealed against the outside, radially outward from the radially outer edge P of the facing region R where the facing surfaces 13a, 14a of the first lens 13 and the second lens 14 are facing each other. In this case, the adhesive medium 40 extends continuously over the outer surface portion 13i of the first lens 13 facing the inner surface of the lens barrel 12 and the outer surface portion 14h of the second lens 14 facing the inner surface of the lens barrel 12 adjacent to the outer surface portion 13i (straight application form).

[0036] The first lens 13 and the second lens 14 to which the adhesive medium 40 has been applied in this manner are assembled as an integrated unit including the adhesive medium 40 and then assembled into the lens barrel 12. Even when the adhesive medium 40 is applied in this manner, the adhesive medium 40 may slightly penetrate into the annular opposing region R during the application process due to surface tension, but it is possible to prevent the adhesive medium 40 from penetrating into a range that exceeds 50% of the thickness of the annular region (the difference between the outer diameter and the inner diameter of the annular region) even partially. This makes it possible to prevent the adhesive medium 40 from exerting a large stress on the first lens 13 due to temperature changes, causing cracks in the first lens 13.

[0037] 5 shows a lens unit 11B according to a third embodiment of the present invention. As shown in the figure, in the lens unit 11B according to this embodiment, each of the lenses 14, 15, 16, and 17, except for the first lens 13, constituting the lens group L, is in point contact with the lens barrel 12 in the circumferential direction in a cross section perpendicular to the optical axis direction (for example, in a cross section perpendicular to the optical axis direction, the inner peripheral surface of the lens barrel 12 is polygonal and the lenses are circular), thereby forming a gap C between the lens barrel 12 and the inner surface in the radial direction (see FIG. 5(a)). Also in this embodiment, an adhesive medium 40 is applied to the outer surface of the second lens 14 radially outward of the radially outer edge P of the facing region R. However, in this case, the adhesive medium 40 extends continuously across the outer surface portion 14i facing the object side of the second lens 14 and the outer surface portion 14h which is the outer peripheral side of the second lens 14 facing the inner surface of the lens barrel 12, so as to completely fill the gap C formed between the inner surface of the lens barrel 12 and the second lens 14, thereby bonding the outer surface portion 14h of the second lens 14 to the inner surface of the lens barrel 12 (see (b) and (c) of Figures 5).

[0038] In this application form of the adhesive medium 40, it is possible to prevent the adhesive medium 40 from being applied completely over 100% of the area of ​​the facing region R (100% of the thickness of the annulus), and therefore it is possible to block the path through which water vapor from the image sensor (imaging element) 100 (see FIG. 2) side reaches the inter-lens space S1, and as a result, the adhesive medium 40 on the outer surface of the second lens 14 and the O-ring 26 on the side surface of the first lens 13 ensure the sealing of the inter-lens space S1 against the outside. In this case, if the adhesive medium 40 is provided over the outer surfaces of the first lens 13 and the second lens 14 near the radially outer edge P of the facing region R, the sealing of the inter-lens space S1 can be further improved.

[0039] The method of making each lens contact the lens barrel 12 in the circumferential direction at points in a cross section perpendicular to the optical axis direction is not limited to making the inner surface of the lens barrel 12 polygonal, but may be a method of making point contact by providing a protruding rib on the inner circumference of the lens barrel 12. Here, point contact refers to point contact in a cross section perpendicular to the optical axis direction, and includes linear contact in the optical axis direction. In the present embodiment, the second lens 14 is bonded to the lens barrel 12, but this is not limiting, and any one or more of the second to fifth lenses may be bonded to the lens barrel 12.

[0040] FIG. 6 shows a lens unit 11C according to a fourth embodiment of the present invention. As shown in the figure, the lens unit 11C according to this embodiment is a modified example of the second embodiment (see FIG. 4), and similarly to the second embodiment, the adhesive medium 40 extends continuously over the outer surface portion 13i of the first lens 13 facing the inner surface of the lens barrel 12 and the outer surface portion 14h of the second lens 14 adjacent to the outer surface portion 13i facing the inner surface of the lens barrel 12. However, in this embodiment, the adhesive medium 40 also adheres the outer surface portion 14h of the lens 14 to the inner surface of the lens barrel 12. Even in such an application form of the adhesive medium 40, the adhesive medium 40 may slightly penetrate into the annular facing region R during the application process due to surface tension, but it is possible to prevent the adhesive medium 40 from penetrating into a range exceeding 50% of the thickness of the annular ring (the difference between the outer diameter and the inner diameter of the annular ring) from the outer periphery of the annular ring.

[0041] As described above, if the adhesive medium 40 is applied to the outer surface of the first lens 13 and / or the second lens 14 radially outward of the radially outer edge P of the opposing region R so that the adhesive medium 40 is not applied to an area exceeding 50% of the thickness of the ring, and so that the inter-lens space S1 is sealed from the outside, then as described above, it is possible to avoid the adhesive medium 40 peeling off from the glass first lens 13 due to radial relative displacement between the lenses 13, 14 caused by the difference in the amount of expansion and contraction of the lenses when temperature changes due to the difference in the linear expansion coefficients of the lenses 13, 14, and the accompanying stress acting on the first lens 13 causing cracks on the surface of the first lens 13.

[0042] Fig. 7 shows a lens unit 11G according to a fifth embodiment of the present invention. In this embodiment, an L-shaped adhesive medium application form as shown in Fig. 2 is applied between a resin intermediate spacer 530 (interposed between the first lens 13 and the second lens 14) and a first glass lens 13. Specifically, an adhesive medium 548 is interposed between the second lens 14 and the intermediate spacer 530, and an L-shaped adhesive medium application form is adopted between the first lens 13 and the intermediate spacer 530 as in Fig. 2. More specifically, in the lens unit 11G according to this embodiment, the adhesive medium 40 is applied over the outer surface (bottom surface; image side surface) of the first lens 13 and the outer surface (outer peripheral side surface facing the inner surface of the lens barrel 12) of the intermediate spacer 530 so as to seal the inter-lens space S1 from the outside, radially outward from the radially outer edge P of the annular opposing region R where the opposing surfaces 13a, 530a of the first lens 13 and the intermediate spacer 530 face each other. The adhesive medium 40 is an adhesive containing an epoxy-based adhesive and having a high hardness, for example, a Shore hardness of D70 or more. In this case, the adhesive medium 40 extends continuously across the outer surface portion 13h on the radially outer side of the surface of the first lens 13 facing the image side, which is not in contact with or opposed to the opposing surface 150a of the intermediate spacer 530, and the outer surface portion 530d, which is the outer peripheral side surface of the intermediate spacer 530 adjacent to the outer surface portion 13h and opposed to the inner surface of the lens barrel 12 (L-shaped application form). In such an application form of the adhesive medium 40, the adhesive medium 40 may slightly penetrate into the annular opposing region R due to surface tension during the application process, but the adhesive medium 40 does not penetrate into a range that exceeds 50% of the thickness of the annulus (the difference between the outer diameter and the inner diameter of the annulus) even partially, so that it is possible to prevent the adhesive medium 40 from applying a large stress to the first lens 13 during temperature changes, causing cracks in the first lens 13. The application form of the adhesive medium 40 between the first lens 13 and the intermediate spacer 530 is not limited to the L-shaped application form, but may be the straight application form without adhesion to the lens barrel 12 described above in relation to Fig. 4, the straight application form with adhesion to the lens barrel 12 described above in relation to Fig. 6, or the application form described above in relation to Fig. 5, that is, the application form in which the adhesive medium 40 is applied so as to completely fill the gap between the intermediate spacer 530 and the lens barrel 12. The adhesive medium for bonding the second lens 14 and the intermediate spacer is not limited to an epoxy adhesive, and other types of adhesives may be used.

[0043] In the above-described embodiments, the shapes of the lenses, lens barrel, etc. are not limited to those in the above-described embodiments. In addition, the above-described embodiments disclose means for preventing condensation on the surface of lens 13, but this does not preclude the use of a conventional method such as installing a moisture absorbing member inside a lens unit in addition to such condensation prevention means. In addition, in all of the above-described embodiments, second lens 14 has low moisture permeability (for example, 30 g / m at a thickness of 0.025 mm). 2It is preferable that the lens cover 13 is made of a resin (such as a material such as COP (cycloolefin polymer) or a resin having COP as a base material) having a thermal resistance of 1000 psi (24 h or less). This not only ensures airtightness between the first and second lenses 13, 14, but also prevents water vapor from entering the space S1 between the lenses due to moisture permeability of the second lens 14 itself. Furthermore, it is possible to combine some or all of the above-mentioned embodiments, or to omit part of the configuration from one of the above-mentioned embodiments, without departing from the gist of the present invention. Furthermore, the technical matters described in each embodiment can be used in other embodiments to obtain the same effects. [Explanation of symbols]

[0044] 11 Lens unit 12 Telescope tube 13 The First Lens 13a Opposite side 14 The Second Lens 14a Opposite surface 40 Adhesive medium 300 Camera Module L lens group O optical axis P radial outer edge R Opposing area S Inner storage space S1 Interlens Space

Claims

1. A lens unit having a lens group formed by arranging a plurality of lenses along an optical axis, and a cylindrical lens barrel having an inner storage space for storing and holding the lens group, the lens group includes a first lens located closest to the object side, and an optical element adjacent to the first lens on the image side thereof; a seal member is interposed between the first lens and the lens barrel to seal a lens group inside the lens barrel from the outside; The first lens and the optical element have annular opposing surfaces that face each other in the optical axis direction and extend radially of the lenses, and an adhesive medium is applied to the outer surface of the first lens and / or the optical element facing the passage between the first lens and the lens barrel through which the sealing member is inserted, radially outward of the radially outer edge of the opposing area where these opposing surfaces face each other, so that the space between the first lens and the optical element is sealed from the outside.

2. 2. The lens unit according to claim 1, wherein the optical elements are a first lens and a second lens adjacent to the first lens on the image side thereof.

3. 3. The lens unit of claim 2, wherein the adhesive medium is applied across an outer surface of the first lens and an outer surface of the second lens.

4. 4. The lens unit according to claim 3, wherein the adhesive medium bonds outer surfaces of the first lens and the second lens to an inner surface of the lens barrel.

5. 3. The lens unit according to claim 2, wherein the adhesive medium bonds an outer surface of the second lens to an inner surface of the lens barrel.

6. The lens unit according to claim 1 , wherein the adhesive medium is not applied to an area that is 50% or more of the thickness of the annular ring of the facing region.

7. The lens unit according to claim 6 , wherein the adhesive medium is not applied on a radially inner side of the facing region.

8. A camera module comprising the lens unit according to claim 1 , and an image sensor disposed at a position where it receives an image formed by the lens unit.

Images