Lens unit

Abstract

To provide a lens unit capable of suppressing reflection of light entering a circumference of a lens surface of a cemented lens in a specific direction.SOLUTION: A lens unit 100 includes: a first lens 6 disposed in an object side L1; and a second lens that is disposed in an image side L2, and is joined to the first lens 6 by an adhesive 8 and constitutes a cemented lens 50. A projection 75 projecting toward the object side L1 is provided on a second flange surface 74 of the second lens 7. An opposing part 66 inclined along a sloped part 76 in a radial inner part of the projection 75 is provided in a first flange surface 64 of the first lens 6. A following conditional expression 1.100<Rb / Ra is satisfied when an effective radius of the cemented lens 50 is set to Ra, a first interval between a lens surface 62 of the first lens 6 and a lens surface 71 of the second lens 7 in the effective radius Ra is set to Ga, a second interval that is three times larger than the first interval Ga is set to Gb, and an outer peripheral side radius that becomes the second interval Gb between the opposing part 66 and the projection 75 is set to Rb.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a lens unit in which a plurality of lenses are held in a lens barrel. [Background technology]

[0002] In a lens unit in which multiple lenses are held in a lens barrel, a cemented lens may be used to reduce aberrations. Such a lens unit is described, for example, in Patent Document 1. This document uses a cemented lens in which a first lens and a second lens disposed on the image side of the first lens are cemented together with an adhesive. The first lens has a first lens surface located on the second lens side and a first flange surface surrounding the first lens surface on the outer periphery. The second lens has a second lens surface located on the first lens side and a second flange surface surrounding the second lens surface on the outer periphery. The adhesive is provided from between the first and second lens surfaces to between the first and second flange surfaces. The distance between the first and second flange surfaces gradually becomes wider radially outward than the distance between the first and second lens surfaces. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-97019 Summary of the Invention [Problem to be solved by the invention]

[0004] Here, when the distance between the first flange surface and the second flange surface is wider than the distance between the first lens surface and the second lens surface, air is more likely to be trapped in the adhesive. If the air bubbles in the adhesive are close to the first lens surface and the second lens surface, the cemented lens is susceptible to the effects of light diffused by the air bubbles. Therefore, when light incident on the cemented lens is diffused by the air bubbles, ghost images are likely to occur in the lens unit due to the diffused light. To address this problem, Patent Document 1 does not describe the positional relationship between the air bubbles and the first and second lens surfaces, making it difficult to solve this problem with the configuration described in Patent Document 1.

[0005] In view of the above problems, an object of the present invention is to provide a lens unit that can suppress reflection in a specific direction of light that has entered the periphery of the lens surface of the cemented lens. [Means for solving the problem]

[0006] In order to solve the above-described problems, a lens unit according to the present invention includes a plurality of lenses and a lens barrel that holds the plurality of lenses, the plurality of lenses including a first lens arranged on a first direction side and a second lens arranged on a second direction side that is opposite to the first direction side and that forms a cemented lens bonded to the first lens with an adhesive, the first lens including a first lens surface that has a concave shape facing the second lens side and a first flange surface that surrounds the first lens surface on the radially outer side, and the second lens including a convex shape corresponding to the first lens surface. the cemented lens includes a second lens surface overlapping the first lens surface, and a second flange surface surrounding the second lens surface on the radially outer side, wherein a convex portion protruding toward the first direction is formed on the second flange surface, and an opposing portion inclined along a radially inner inclined portion of the convex portion is formed on the first flange surface, the adhesive is provided from between the first lens surface and the second lens surface to a radially outer position beyond the opposing portion and the convex portion, an effective radius of the cemented lens is Ra, a first distance between the first lens surface and the second lens surface at the effective radius Ra is Ga, and 3 of the first distance Ga is When the second distance Gb is a factor of 1, and the outer radius Rb is a factor of 2, the second distance Gb between the opposing portion and the convex portion is a factor of 1, the following conditional expression is satisfied: 1.100 <Rb / Ra The present invention is characterized in that:

[0007] In the present invention, the cemented lens has an effective radius Ra of the cemented lens, a first distance between the first lens surface and the second lens surface at the effective radius Ra is Ga, a second distance Gb that is three times the first distance Ga, an outer radius Rb at which the second distance Gb is formed between the opposing portion and the convex portion, and a conditional expression 1.100 <Rb / Ra satisfies the condition. Here, when the second distance Gb is three times the first distance Ga, air is more likely to be trapped in the adhesive, making it easier for bubbles to form. Therefore, by doing this, the air bubble portion in the adhesive can be positioned appropriately from the effective radius of the cemented lens. As a result, the present invention can suppress the occurrence of ghost images due to the diffusion of light in the air bubble portion in the adhesive. In other words, when the value of the conditional expression is below the lower limit, the air bubble portion in the adhesive is closer to the first lens surface and the second lens surface, and is affected by the diffusion of light in the air bubble portion, making it easier for ghost images to form in the lens unit.

[0008] In the present invention, the lens unit satisfies the following conditional formula, where Ra is an effective radius of the cemented lens, Ga is a first distance between the first lens surface and the second lens surface at the effective radius Ra, Gb is a second distance three times the first distance Ga, and Rb is an outer radius on the outer periphery where the second distance Gb is formed between the opposing portion and the convex portion. 1.100 <Rb / Ra<1.500 It is preferable to satisfy the following condition. This makes it possible to reduce the influence of ghost images caused by light diffusion in air bubbles in the adhesive, and also to prevent the lens unit from becoming large. In other words, if the value of the conditional expression exceeds the upper limit, the cemented lens becomes large, and the lens unit becomes large.

[0009] In the present invention, it is preferable that the distance between the opposing portion and the convex portion increases radially outward from a first boundary between the first lens surface and the opposing portion and from a second boundary between the second lens surface and the inclined portion. In this way, when the first lens and the second lens are bonded together, excess adhesive between the first lens surface and the second lens surface can be easily discharged radially outward.

[0010] In the present invention, it is preferable that the first lens surface and the facing portion are continuous while being curved, and the second lens surface and the inclined portion of the convex portion are continuous while being curved, thereby making it difficult for air bubbles to form in the adhesive when excess adhesive between the first lens surface and the second lens surface flows into an adhesive reservoir.

[0011] In the present invention, it is preferable that the first flange surface is provided with an adhesive reservoir recessed toward the first direction, and the adhesive reservoir has the facing portion on its radially inner side. In this way, when the first lens and the second lens are cemented together, excess adhesive 8 between the first lens surface and the second lens surface is stored in the adhesive reservoir. This makes it possible to apply a sufficient amount of adhesive without causing adhesive discontinuities or air bubbles. It is also possible to prevent the adhesive from leaking out of the cemented lens.

[0012] In the present invention, it is preferable that the adhesive reservoir has a bottom portion that is continuous with the opposing portion and faces the second direction, and the bottom portion is curved toward the first direction. In this way, air bubbles are less likely to be generated in the adhesive when the adhesive flows into the adhesive reservoir.

[0013] In the present invention, the center of the bottom portion in the radial direction is located radially outward from the protrusion. In this way, the adhesive reservoir spreads radially outward from the convex portion. This increases the adhesive bonding area when viewed from the optical axis direction, making it easier to ensure the bonding strength between the first lens and second lens 7.

[0014] In the present invention, it is preferable that the second flange surface includes a step portion protruding toward the first direction, and the adhesive reservoir portion includes an abutment surface portion that extends linearly from the radial outside of the bottom portion toward the second direction and abuts against the step portion from the radial outside. In this way, when the first lens and the second lens are joined, the abutment surface portion and the step portion abut in the radial direction, so that the optical axes L of the first lens and the second lens are aligned.

[0015] In the present invention, it is preferable that the first flange surface and the second flange surface have polished surfaces on which the adhesive is applied. In this way, the polished surfaces on which the adhesive is applied are polished, making the surfaces smooth. Therefore, the adhesive easily adheres to the surfaces, making it difficult for the first lens and the second lens to peel off. [Effects of the Invention]

[0016] In the present invention, when the effective radius of the cemented lens is Ra, the first distance between the first lens surface and the second lens surface at the effective radius Ra is Ga, the second distance that is three times the first distance Ga is Gb, and the outer radius at which the second distance Gb is formed between the opposing portion and the convex portion is Rb, the following conditional expression is satisfied: 1.100 <Rb / Ra This makes it possible to suppress the occurrence of ghost images due to light diffusion in air bubbles in the adhesive in a lens unit that includes a cemented lens. [Brief explanation of the drawings]

[0017] [Figure 1] 1 is a cross-sectional view of a lens unit to which the present invention is applied. [Figure 2] FIG. 2 is a cross-sectional view of a cemented lens. [Figure 3] FIG. 2 is a perspective view of a first lens. [Figure 4] FIG. 2 is a perspective view of a second lens. [Figure 5] FIG. 3 is an enlarged cross-sectional view showing an end portion of a cemented lens. DETAILED DESCRIPTION OF THE INVENTION

[0018] An embodiment of the present invention will be described with reference to the drawings. In the drawings referred to in the following description, the number and scale of each component are different so that each component can be recognized on the drawing. In the following description, L1 is assigned to the object side and L2 is assigned to the image side in the direction of the optical axis L.

[0019] (lens unit) FIG. 1 is a cross-sectional view of a lens unit to which the present invention is applied. The lens unit 100 of this embodiment is used in an optical device such as an imaging device. The lens unit 100 has a substantially uniform configuration throughout the entire circumference around an optical axis L. The lens unit 100 shown in FIG. 1 has a plurality of lenses 10 and a lens barrel 20 that holds the plurality of lenses 10. An imaging element is provided on the image side L2 of the lens barrel 20. The imaging element is a CMOS or the like.

[0020] As shown in FIG. 1, multiple lenses 10 are arranged along an optical axis L. The multiple lenses 10 consist of lens 1, lens 2, lens 3, lens 4, and lens 5. Lens 1 is arranged closest to the object side (first direction side) L1, and lens 5 is arranged closest to the image side (second direction side) L2. Lens 4 is held in a lens barrel 20 while being held by a holder 13. In this embodiment, lens 1 is arranged so as to close an object-side opening 20a of the lens barrel 20. A light-transmitting plate-like member 14 located closest to the image side L2 closes the image-side opening 20a of the lens barrel 20. It is arranged to close the opening 20b.

[0021] Lens 1 has a convex shape on the lens surface on the object side L1 and a concave shape on the lens surface on the image side L2. Lens 2 has a convex shape on the lens surface on the object side L1 and a concave shape on the lens surface on the image side L2. Lens 3 has a convex shape on the lens surface on the object side L1 and a convex shape on the lens surface on the image side L2. Lens 4 has a convex shape on the lens surface on the object side L1 and a convex shape on the lens surface on the image side L2. Lens 5 has a concave shape on the lens surface on the object side L1 and a convex shape on the lens surface on the image side L2. Lens 5 consists of a cemented lens 50.

[0022] The lens unit 100 has an annular light-shielding sheet 11 between the lens 2 and the lens 3. The lens unit 100 has an annular diaphragm 12 between the lens 4 and the lens 5.

[0023] (50mm cemented lens) FIG. 2 is a cross-sectional view of the cemented lens 50. FIG. 3 is a perspective view of the first lens 6. FIG. 4 is a perspective view of the second lens 7. As shown in FIGS. 1 and 2, the cemented lens 50 is made of a first lens 6 arranged on the object side L1 (first direction side) and a second lens 7 arranged on the image side L2 (second direction side) opposite (in the opposite direction) to the object side L1. The first lens 6 and the second lens 7 are cemented together with an adhesive 8. In this embodiment, the adhesive 8 is a UV-curable adhesive. It is preferable that the adhesive 8 be made of a material that retains elasticity even after curing.

[0024] The first lens 6 is made of resin. As shown in Figures 2 and 3, the first lens 6 has a lens surface 61 on the object side L1 that is concave, and a lens surface 62 (first lens surface) on the image side L2 that is concave. The first lens 6 has a first flange portion 63 that surrounds the lens surfaces 61 and 62 on the radially outer side. Therefore, the first lens 6 has a first flange surface 64 that surrounds the lens surface 62 on the radially outer side.

[0025] The second lens 7 is made of resin. As shown in FIGS. 2 and 4, the second lens 7 has a lens surface 71 (second lens surface) on the object side L1 that has a convex shape, and a lens surface 72 on the image side L2 that has a convex shape. The second lens 7 has a second flange portion 73 that surrounds the lens surfaces 71 and 72 on the radially outer side. Therefore, the second lens 7 has a second flange surface 74 that surrounds the lens surface 71 on the radially outer side. The lens surface 71 has a convex shape that corresponds to the lens surface 62 and overlaps with the lens surface 62. The lens surface 71 and the lens surface 62 have approximately the same radius of curvature.

[0026] The second flange surface 74 is provided with a convex portion 75 that is adjacent to the lens surface 71 and that protrudes toward the object side L1. As shown in FIG. 3, the convex portion 75 extends in an annular shape. The convex portion 75 has an arc-shaped cross section. An inclined portion 76 on the radially inner side of the convex portion 75 and the lens surface 71 are continuous with each other while being curved. In other words, the inclined portion 76 and the lens surface 71 are continuous with each other via a curved surface 70 that curves toward the image side L2.

[0027] The second flange surface 74 is provided with mounting surface portions 77 that protrude toward the object side L1 radially outward from the convex portions 75. As shown in FIG. 3 , the mounting surface portions 77 extend in the circumferential direction, and three mounting surface portions 77 are provided at equal intervals in the circumferential direction. A flat surface 79 of each mounting surface portion 77 facing the object side L1 intersects with the optical axis L. The flat surface 79 of each mounting surface portion 77 abuts against the first flange surface 64 when the first lens 6 and the second lens 7 are cemented together. Each mounting surface portion 77 is provided with a step portion 78 that protrudes toward the object side L1. The circumferential width of each step portion 78 is narrower than the circumferential width of the mounting surface portion 77. When the first lens 6 and the second lens 7 are cemented together, the step portion 78 is inserted into an adhesive reservoir portion 65 (described later) and abuts against an abutment surface portion 68 of the adhesive reservoir portion 65 from the radially inner side.

[0028] 2 and 3, the first flange surface 64 is provided with an adhesive reservoir 65 that is adjacent to the lens surface 62 and is recessed toward the object side L1. The adhesive reservoir 65 extends in an annular shape. When the first lens 6 and the second lens 7 are cemented together, a convex portion 75 is inserted into the adhesive reservoir 65. The adhesive reservoir 65 includes a facing portion 66 located radially inward, a bottom portion 67 that is continuous with the facing portion 66 and faces the image side L2, and an abutment surface portion 68 that extends from the radially outer side of the bottom portion 67 toward the image side L2.

[0029] The facing portion 66 is adjacent to the lens surface 62 and is inclined along the inclined portion 76. The facing portion 66 and the lens surface 62 are continuous while being curved. In other words, the facing portion 66 and the lens surface 62 are continuous via the curved surface 60 that is curved toward the image side L2.

[0030] The bottom portion 67 curves toward the object side L1. The radial center of the bottom portion 67 is located radially outward from the convex portion 75. In other words, the adhesive reservoir portion 65 extends radially outward from the convex portion 75. The abutment surface portion 68 extends linearly toward the image side L2. When the first lens 6 and the second lens 7 are cemented together, the abutment surface portion 68 abuts radially against a radially outer side surface 78a of the step portion 78.

[0031] The first flange surface 64 is provided with a flat surface 69 that intersects with the optical axis L, radially outward from the adhesive reservoir portion 65. The flat surface 69 abuts against a flat surface 79 of the mounting surface portion 77 when the first lens 6 and the second lens 7 are joined together.

[0032] As shown in Fig. 2, adhesive 8 is provided over the entire area between first lens 6 and second lens 7, including between lens surface 62 and lens surface 71 and between first flange surface 64 and second flange surface 74. More specifically, adhesive 8 is provided from between lens surface 62 and lens surface 71 to a radially outer position beyond opposing portion 66 and inclined portion 76. Here, polished surfaces C are provided on first flange surface 64 and second flange surface 74 in the areas where adhesive 8 is provided. Polished surfaces C are machined to a level equivalent to a mirror finish.

[0033] As shown in FIG. 2, in this embodiment, the first lens 6 has a larger outer diameter than the second lens 7. Therefore, the outer peripheral portion of the first flange 63 protrudes radially outward beyond the second flange 73. Meanwhile, the lens barrel 20 is formed with a step 21 that supports, on the image side L2, the outer peripheral portion of the first flange 63 that protrudes radially inward beyond the second flange 73. Furthermore, the lens barrel 20 has an annular end plate 22 that protrudes radially inward beyond the step 21 toward the image side L2. Here, an image-side opening 20b is formed in the center of the end plate 22, and a light-transmitting plate member 14 is fixed to the end face of the end plate 22 on the image side L2.

[0034] (More about adhesive lens bonding) The bonding of the first lens 6 and the second lens 7 with the adhesive 8 will now be described. Fig. 5 is an enlarged cross-sectional view showing the edge of the cemented lens 50.

[0035] In this embodiment, when bonding the first lens 6 and the second lens 7, for example, adhesive 8 is applied to the lens surface 62 side of the first lens 6, and then the first lens 6 and the second lens 7 are overlapped. As a result, as shown in FIG. 5 , the adhesive 8 spreads between the first lens 6 and the second lens 7, and by subsequently curing the adhesive 8, the first lens 6 and the second lens 7 are bonded together by the adhesive 8. In this bonding process, as the adhesive 8 spreads between the first lens 6 and the second lens 7, the adhesive 8 attempts to flow outward from between the first lens 6 and the second lens 7, but the adhesive 8 accumulates in adhesive reservoir 65. Therefore, the amount of adhesive 8 that flows outward from between the first lens 6 and the second lens 7 can be reduced, making it less likely that a gap in the adhesive 8 will occur between the first lens 6 and the second lens 7.

[0036] When the first lens 6 and the second lens 7 are bonded together, the flat surfaces 69 and 79 come into contact with each other, thereby positioning the first lens 6 and the second lens 7 in the direction of the optical axis L. Furthermore, when the first lens 6 and the second lens 7 are bonded together, the abutting surfaces 68 and the side surfaces 78a come into contact with each other, thereby aligning the optical axes L of the first lens 6 and the second lens 7. This allows the distance between the first lens 6 and the second lens 7 to be controlled to an appropriate dimension. Therefore, discontinuities in the adhesive 8 are unlikely to occur between the first lens 6 and the second lens 7. Furthermore, the distance between the facing portion 66 and the convex portion 75 increases radially outward from the first boundary 600 between the lens surface 62 and the facing portion 66 and the second boundary 700 between the lens surface 71 and the inclined portion 76. Therefore, when the first lens 6 and the second lens 7 are bonded together, excess adhesive 8 between the lens surface 62 and the lens surface 71 is likely to be smoothly discharged toward the adhesive reservoir 65.

[0037] As shown in FIG. 5 , in the cemented lens 50, if the effective radius of the cemented lens 50 is Ra, the first distance between the lens surface 62 and the lens surface 71 at the effective radius Ra is Ga, the second distance that is three times the first distance Ga is Gb, and the outer radius at which the second distance Gb is formed between the facing portion 66 and the convex portion 75 is Rb, then the following conditional expression is satisfied: 1.100 <Rb / Ra<1.500 In this embodiment, the effective radius Ra is 1.27 mm, the first interval Ga is 0.012 mm, the second interval Gb is 0.038 mm, and the outer radius Rb is 1.724 mm. Therefore, Rb / Ra is 1.358.

[0038] (Action and effect) In the lens unit 100 of this embodiment, when the effective radius of the cemented lens 50 is Ra, the first distance between the lens surface 62 and the lens surface 71 at the effective radius Ra is Ga, the second distance that is three times the first distance Ga is Gb, and the outer radius at which the second distance Gb is formed between the facing portion 66 and the convex portion 75 is Rb, the following conditional expression is satisfied: 1.100 <Rb / Ra<1.500 where R is the radius of the adhesive 8 and R is the effective radius of the cemented lens 50. The following expression is satisfied: ...

[0039] In this embodiment, the distance between the facing portion 66 and the convex portion 75 increases radially outward from a first boundary portion 600 between the lens surface 62 and the facing portion 66 and from a second boundary portion 700 between the lens surface 71 and the inclined portion 76. This makes it easier for excess adhesive 8 between the lens surface 62 and the lens surface 71 to be smoothly discharged toward the adhesive reservoir portion 65 when the first lens 6 and the second lens 7 are bonded together.

[0040] In this embodiment, lens surface 62 and opposing portion 66 are continuous while being curved. Furthermore, lens surface 72 and inclined portion 76 of convex portion 75 are continuous while being curved. Therefore, when excess adhesive 8 between lens surface 62 and lens surface 71 flows into adhesive reservoir 65, air bubbles are unlikely to form in adhesive 8.

[0041] The first flange surface 64 is provided with an adhesive reservoir 65 recessed toward the object side L1. The adhesive reservoir 65 has an opposing portion 66 on its radially inner side that is adjacent to the first lens surface 62. As a result, when the first lens 6 and the second lens 7 are cemented together, excess adhesive 8 between the lens surface 62 and the lens surface 71 is stored in the adhesive reservoir 65. This makes it possible to apply a sufficient amount of adhesive 8 so that the adhesive 8 does not run out or air bubbles do not form. Furthermore, it is possible to prevent the adhesive 8 from leaking out of the cemented lens 50.

[0042] In this embodiment, the adhesive reservoir 65 faces the image side L2, continuing from the opposing portion 66, and includes a bottom 67 that curves toward the object side L1. This makes it difficult for air bubbles to form in the adhesive 8 when the adhesive 8 flows into the adhesive reservoir 65.

[0043] The radial center of bottom portion 67 is located radially outward from convex portion 75. In other words, adhesive reservoir portion 65 extends radially outward from convex portion 75. This makes it possible to increase the bonding area of ​​adhesive 8 when viewed from the direction of optical axis L, making it easier to ensure the bonding strength between first lens 6 and second lens 7.

[0044] The second flange surface 74 has a step portion 78 that protrudes toward the object side L1. The adhesive reservoir 65 extends linearly from the radially outer side of the bottom portion 67 toward the image side L2, and has an abutment surface portion 68 that abuts against a side surface 78a of the step portion 78 from the radially outer side. Therefore, when the first lens 6 and the second lens 7 are cemented together, the abutment surface portion 68 and the side surface 78a abut against each other in the radial direction, so that the optical axes L of the first lens 6 and the second lens 7 are aligned.

[0045] Furthermore, in this embodiment, polished surfaces C are provided on the first flange surface 64 and the second flange surface 74 in the areas where the adhesive 8 is applied. The polished surfaces C are machined to a polished finish equivalent to a mirror finish. If the first flange surface 64 and the second flange surface 74 were not polished, the adhesive 8 would not easily flow into the fine irregularities of the surface, making it difficult for the adhesive 8 to adhere to the surface. This would make it easier for the first lens 6 and the second lens 7 to peel off. In contrast, in this embodiment, the polished surfaces C, where the adhesive 8 is applied, are polished, making the surface smooth. This makes it easier for the adhesive 8 to adhere to the surface, making it difficult for the first lens 6 and the second lens 7 to peel off.

[0046] (Other Examples) In the above embodiment, the first lens 6 is arranged on the object side L1 (first direction side) and the second lens 7 is arranged on the image side L2 (second direction side), but the first lens 6 may be arranged on the image side L2 (second direction side) and the second lens 7 may be arranged on the object side L1 (first direction side).

[0047] In the above embodiment, the polished surfaces C are provided on the first flange surface 64 and the second flange surface 74 where the adhesive 8 is provided, but the polished surfaces C do not necessarily have to be provided. [Explanation of symbols]

[0048] 1...lens, 2...lens, 3...lens, 4...lens, 5...lens, 6...first lens, 7...second lens, 8...adhesive, 10...plural lenses, 11...light-shielding sheet, 12...diaphragm, 13...holder, 14...light-transmitting plate-like member, 20...lens barrel, 20a...object-side opening, 20b...image-side opening, 21...step portion, 22...end plate portion, 50...cemented lens, 60...curved surface, 61...lens surface, 62...lens surface (first lens surface), 63...first flange portion, 64...first flange surface, 65...adhesive reservoir portion, 66...opposing portion, 67...bottom portion, 68...abutment surface portion, 69...flat surface, 70...curved surface, 71...lens surface (second lens surface), 72...lens surface, 73...second flange portion, 74...second flange surface, 75...convex portion, 76...inclined portion, 77...mounting surface portion, 78...step portion, 78a...side surface, 79...flat surface, 100...lens unit, 600...first boundary portion, 700...second boundary portion, C...polished surface, Ga...first interval, Gb...second interval, L...optical axis, L1...object side (first L1...Image side (second direction side), L2...Image side (second direction side), Ra...Effective radius, Rb...Outer radius

Claims

1. A lens unit having a plurality of lenses and a lens barrel that holds the plurality of lenses, the plurality of lenses include a first lens arranged on a first direction side, and a second lens arranged on a second direction side opposite to the first direction side, and bonded to the first lens with an adhesive to form a cemented lens; the first lens includes a first lens surface having a concave shape facing the second lens, and a first flange surface surrounding the first lens surface on the radially outer side, the second lens includes a second lens surface having a convex shape corresponding to the first lens surface and overlapping the first lens surface, and a second flange surface surrounding the second lens surface on the radially outer side, A convex portion protruding toward the first direction side is formed on the second flange surface, The first flange surface has an opposing portion inclined along the radially inner inclined portion of the protrusion, the adhesive is provided from between the first lens surface and the second lens surface to a radially outer position beyond the opposing portion and the convex portion, The effective radius of the cemented lens is Ra, a first distance between the first lens surface and the second lens surface at the effective radius Ra is defined as Ga; a second interval Gb that is three times the first interval Ga; When the outer circumferential radius that forms the second distance Gb between the opposing portion and the convex portion is Rb, the following conditional expression is satisfied: 1.100<Rb / Ra Fulfilling the first lens surface and the opposing portion are continuous and curved, The lens unit is characterized in that the second lens surface and the inclined portion of the convex portion are continuous while being curved.

2. A lens unit having a plurality of lenses and a lens barrel that holds the plurality of lenses, The plurality of lenses include a first lens disposed on a first direction side and a second lens disposed on an opposite side to the first direction side. a second lens disposed on the second direction side, which is a direction of the first lens, and configured as a cemented lens bonded to the first lens with an adhesive, the first lens includes a first lens surface having a concave shape facing the second lens, and a first flange surface surrounding the first lens surface on the radially outer side, the second lens includes a second lens surface having a convex shape corresponding to the first lens surface and overlapping the first lens surface, and a second flange surface surrounding the second lens surface on the radially outer side, A convex portion protruding toward the first direction side is formed on the second flange surface, The first flange surface has an opposing portion inclined along the radially inner inclined portion of the protrusion, the adhesive is provided from between the first lens surface and the second lens surface to a radially outer position beyond the opposing portion and the convex portion, The effective radius of the cemented lens is Ra, a first distance between the first lens surface and the second lens surface at the effective radius Ra is defined as Ga; a second interval Gb that is three times the first interval Ga; When the outer circumferential radius that forms the second distance Gb between the opposing portion and the convex portion is Rb, the following conditional expression is satisfied: 1.100<Rb / Ra Fulfilling The first flange surface has an adhesive reservoir recessed toward the first direction, the adhesive reservoir portion includes the facing portion on a radially inner side thereof, the adhesive reservoir portion includes a bottom portion that is continuous with the opposing portion and faces the second direction side, The lens unit is characterized in that the bottom portion is curved toward the first direction side.

3. The effective radius of the cemented lens is Ra, a first distance between the first lens surface and the second lens surface at the effective radius Ra is defined as Ga; a second interval Gb that is three times the first interval Ga; When the outer circumferential radius that forms the second distance Gb between the opposing portion and the convex portion is Rb, the following conditional expression is satisfied: 1.100<Rb / Ra<1.500 3. The lens unit according to claim 1, wherein the following is satisfied:

4. 4. The lens unit according to claim 1, wherein the distance between the opposing portion and the convex portion increases radially outward from a first boundary portion between the first lens surface and the opposing portion and a second boundary portion between the second lens surface and the inclined portion.

5. The lens unit according to claim 2 , wherein the center of the bottom portion in the radial direction is located radially outward from the convex portion.

6. The second flange surface includes a step portion that protrudes toward the first direction, The lens unit according to claim 2 or 5, wherein the adhesive reservoir portion extends linearly from the radially outer side of the bottom portion toward the second direction side and has an abutment surface portion that abuts against the step portion from the radially outer side.

7. 7. The lens unit according to claim 1, wherein the first flange surface and the second flange surface have polished surfaces at portions where the adhesive is applied.

Images