Lens unit

Abstract

To provide a lens unit that can suppress fogging of a first lens.SOLUTION: A lens unit 1 has: a lens barrel 20 that holds a first lens 11, a second lens 12, and a plurality of lenses; and an annular first elastic member 31 that is arranged between the first lens 11 and the second lens 12. The second lens 12 includes a second ring part 124 on its outer peripheral surface where a gate trace G1 remains. The lens barrel 20 includes a first cylinder part 21 that holds the first lens 11, and a second cylinder part 22 that is arranged inside the first cylinder part 21 and holds the second lens 12 and the plurality of lenses. The second cylinder part 22 includes a first portion 221 that holds the second lens 12. An inner peripheral surface of the first portion 221 is provided with a recess 223 on the inside of which the gate trace G1 is located. The first elastic member 31 is compressed between the first lens 11 and the second lens 12 to an extent that the first lens 11 and the second lens 12 are not brought into contact with each other.SELECTED DRAWING: Figure 2

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] Imaging devices installed in automobiles, surveillance cameras, etc. use a lens unit in which multiple lenses are housed in a lens holder. In this lens unit, the object-side lens surface of the first lens closest to the object is exposed to the outside through the lens barrel.

[0003] Such a lens unit is described, for example, in Patent Document 1. In this document, a first lens and multiple lenses, including a second lens arranged on the image side of the first lens, are housed in a lens barrel made of resin. The lens barrel includes a first housing section that houses the first lens and a second housing section that houses multiple lenses, including the second lens. An elastic member is disposed between the flange portion of the first lens and the flange portion of the second lens. The first lens is locked in the first housing section by thermal caulking, and the elastic member is compressed between the flange portion of the first lens and the flange portion of the second lens, thereby maintaining a constant airtightness inside the lens unit.

[0004] Here, since the second lens is made of plastic, a gate mark is formed on the outer peripheral surface of the flange portion of the second lens. Generally, when the second lens is accommodated in the second housing portion, the gate mark is provided on a flat portion obtained by cutting out a part of the outer peripheral surface of the flange portion so that the gate mark does not interfere with the inner peripheral surface of the second housing portion. In this case, the outer diameter shape of the flange portion is D-shaped in plan view. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-154123 Summary of the Invention [Problem to be solved by the invention]

[0006] As described above, when a flat portion is provided on the outer peripheral surface of the flange of the second lens, the radial width of the flange where the flat portion is provided is small in a plan view. Therefore, the contact area with the elastic member at this portion is small, preventing the elastic member from properly adhering to the flange of the second lens. As a result, when the lens unit is used for a long period of time, moisture may penetrate the elastic member and enter the interior of the lens unit.

[0007] In view of the above problems, an object of the present invention is to provide a lens unit that can suppress fogging of the first lens. [Means for solving the problem]

[0008] In order to solve the above problem, a lens unit according to the present invention includes a first lens arranged closest to the object along an optical axis, a second lens made of resin arranged on the image side of the first lens, a plurality of lenses arranged on the image side of the second lens, a lens barrel that holds the first lens, the second lens, and the plurality of lenses, and a first annular elastic member that is arranged between the first lens and the second lens, wherein the first lens includes a first lens portion and a first annular portion that surrounds the first lens portion, and the second lens includes a second lens portion and a second annular portion that surrounds the second lens portion and has gate marks on its outer peripheral surface, and the lens barrel includes a first cylindrical portion that holds the first lens, and a second cylindrical portion that is radially outward from the first cylindrical portion. and a second cylindrical portion that holds the second lens and the plurality of lenses on the inside, the second cylindrical portion having a cylindrical first portion that holds the second lens, the inner surface of the first portion having a gate mark accommodating recess with the gate mark located on the inside, the open end facing the object side, and the first elastic member being compressed between the first annular portion and the second annular portion to such an extent that the first lens and the second lens do not come into contact with each other.

[0009] In the present invention, the second lens includes a second annular portion, the outer peripheral surface of which is a gate mark, and a gate mark receiving recess, the gate mark being located inside, is provided on the inner peripheral surface of the first portion, with its open end facing the object side. Because the gate mark is received in the gate mark receiving recess, there is no need to form the gate mark on the flat portion of the outer peripheral surface of the second annular portion. In other words, there is no need to provide a flat portion on the outer peripheral surface of the second annular portion, and the outer diameter shape of the second annular portion remains circular. Therefore, compared to when the gate mark is formed on the flat portion of the outer peripheral surface of the lens, a contact area for the first elastic member can be ensured, allowing the first elastic member to properly adhere to the flange portion of the second lens. As a result, airtightness between the first lens and the second lens can be ensured, thereby suppressing fogging of the first lens.

[0010] In the present invention, the first elastic member is compressed between the first annular portion and the second annular portion to the extent that the first lens and the second lens do not abut against each other. Therefore, the amount of compression of the first elastic member is easier to manage compared to when the first lens and the second lens abut against each other. As a result, it is easy to increase the airtightness inside the lens barrel, and fogging of the image-side lens surface of the first lens can be suppressed. Furthermore, because the first lens and the second lens do not abut against each other, when the first lens is held in the first barrel portion, the first elastic member is compressed, and a large force is less likely to be directly applied to the second lens and the multiple lenses. Therefore, when the first lens is held in the first barrel portion, damage to the second lens and subsequent lenses can be suppressed.

[0011] In the present invention, it is preferable that recesses are provided at a plurality of positions in the circumferential direction on the inner peripheral surface of the first portion, and some of the recesses serve as the gate mark accommodating recesses. In this way, if the center of the second lens is misaligned with the optical axis when the second lens is held in the first portion, the center of the second lens can be aligned with the optical axis by rotating the second lens at equal intervals around the optical axis L relative to the first portion.

[0012] In the present invention, it is preferable that the second lens has an annular step portion that protrudes toward the object side of the second annular portion and is capable of positioning the first elastic member in the radial direction. This makes it easy to position the first elastic member in the radial direction. As a result, it is possible to prevent insufficient airtightness between the first lens and the second lens due to misalignment of the first elastic member.

[0013] In the present invention, it is preferable that a third lens of the plurality of lenses adjacent to the second lens on the image side includes a third lens portion and a third annular portion that surrounds the third lens portion, and that the surface of the third annular portion facing the object side abuts the surface of the second annular portion facing the image side in the optical axis direction and is located closer to the object side than the image-side bottom surface of the gate mark accommodating recess. In this way, the gate mark does not come into contact with the bottom surface of the gate mark accommodating recess, so that the third lens can reliably position the second lens.

[0014] In the present invention, a mode can be adopted in which a light-shielding sheet is disposed between the second lens and the third lens.

[0015] In the present invention, it is preferable that first ribs for radially positioning the second lens be provided at multiple locations on the inner peripheral surface of the first portion. In this way, even if distortion is likely to occur due to the external shape of the lens barrel, the first ribs can prevent misalignment of the second lens due to distortion of the first portion.

[0016] In the present invention, it is preferable that the lens barrel includes a contact surface portion between the first and second cylindrical portions that contacts the first annular portion from the image side, the contact surface portion including an annular groove portion recessed toward the image side, and an annular second elastic member compressed between the first annular portion and the groove portion disposed in the groove. This makes it easier to ensure airtightness between the first lens and the second lens.

[0017] In the present invention, it is preferable that the second cylindrical portion includes a second portion that holds the plurality of lenses, and that second ribs that position the plurality of lenses in the radial direction are provided on the inner peripheral surface of the second portion at multiple locations in the circumferential direction. In this way, even if distortion is likely to occur due to the external shape of the lens barrel, the second ribs can prevent misalignment of the plurality of lenses caused by distortion of the second portion.

[0018] In the present invention, it is preferable that the lens barrel includes a positioning step that abuts, from the image side, against the image-side lens that is positioned furthest to the image side among the plurality of lenses, and the first elastic member overlaps the positioning step in the optical axis direction. In this way, the force in the optical axis direction when the first elastic member is compressed by the first lens is concentrated on the positioning step. This makes it possible to prevent distortion of the lens barrel when the first lens is attached. [Effects of the Invention]

[0019] In the present invention, the second lens includes a second annular portion on its outer peripheral surface where a gate mark remains, and the inner peripheral surface of the first portion includes a gate mark receiving recess with its open end facing the object side, with the gate mark located on the inside. This ensures a larger contact area for the first elastic member to abut, compared to when the gate mark is formed on a flat portion on the outer peripheral surface of the lens. This ensures airtightness between the first lens and the second lens, thereby preventing fogging of the image-side lens surface of the first lens. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a cross-sectional view of a lens unit to which the present invention is applied. [Figure 2] FIG. 2 is an exploded perspective view of the lens unit. [Figure 3] FIG. 2 is a cross-sectional view of a lens barrel. [Figure 4] FIG. 2 is a plan view of the lens barrel as seen from the object side. DETAILED DESCRIPTION OF THE INVENTION

[0021] 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, La is attached to the object side and Lb is attached to the image side in the direction of the optical axis L.

[0022] (Lens unit configuration) FIG. 1 is a cross-sectional view of a lens unit to which the present invention is applied. FIG. 2 is an exploded perspective view of the lens unit. The lens unit 1 of this embodiment is used in an optical device such as an imaging device. The lens unit 1 has a substantially uniform configuration throughout the entire circumference of the optical axis L. The lens unit 1 shown in FIG. 1 has a wide-angle lens 10 having multiple lenses arranged in the direction of the optical axis L, and a lens barrel 20 that holds the wide-angle lens 10 inside. An image sensor is provided on the image side Lb of the lens barrel 20. The image sensor is a CMOS or the like.

[0023] (wide-angle lens) 1 and 2, the wide-angle lens 10 has, for example, a lens configuration of 5 groups and 6 lenses. In this embodiment, the wide-angle lens 10 has a first lens 11 arranged closest to the object side La. The wide-angle lens 10 includes, from the object side La to the image side Lb, a first lens 11 having negative power, a second lens 12 having negative power, a third lens 13 having positive power, a fourth lens 14 having positive power, and a cemented lens 18 (a fifth lens 15 and a sixth lens 16) having positive power. The plurality of lenses are made up of the third lens 13 through the cemented lens 18.

[0024] The first lens 11 is a glass lens or a plastic lens. The first lens 11 is a meniscus lens. The first lens 11 has a first lens surface 111 on the object side La that is a convex curved surface protruding toward the object side La, and a second lens surface 112 on the image side Lb that is a concave curved surface recessed toward the object side La. The first lens 11 includes a first lens portion 113 and a first annular portion 114 that surrounds the first lens portion 113. The first lens surface 111 and the second lens surface 112 constitute the first lens portion 113. A flange surface 115 of the first annular portion 114 that faces the image side Lb is located radially outward from the second lens surface 112.

[0025] The second lens 12 is a plastic lens. The second lens 12 has a first lens surface 121 on the object side La that is a convex curved surface protruding toward the object side La, and a second lens surface 122 on the image side Lb that is a concave curved surface recessed toward the object side La. The second lens 12 includes a second lens portion 123 and a second annular portion 124 that surrounds the second lens portion 123 and has a gate mark G1 remaining on its outer circumferential surface. The first lens surface 121 and the second lens surface 122 constitute the second lens portion 123. The outer shape of the second annular portion 124 is circular in the direction of the optical axis L. The gate mark G1 is formed when the second lens 12 is resin-molded. The gate mark G1 protrudes slightly radially outward from the outer circumferential surface of the second annular portion 124.

[0026] Flange surface 125 of second annular portion 124 facing object side La is located radially outward from first lens surface 121. Flange surface 126 of second annular portion 124 facing image side Lb is located radially outward from second lens surface 122. Second annular portion 124 also includes an annular step portion 127 that protrudes toward object side La. Annular step portion 127 positions first elastic member 31 in the radial direction.

[0027] The third lens 13 is a plastic lens. The first lens surface 131 of the third lens 13 on the object side La is a convex curved surface that protrudes toward the object side La, and the second lens surface 132 of the third lens 13 on the image side Lb is a concave curved surface that is recessed toward the object side La. The third lens 13 includes a third lens portion 133 and a third annular portion 134 that surrounds the third lens portion 133 and has a gate mark G2 remaining on a flat portion 134a of the outer circumferential surface. The first lens surface 131 and the second lens surface 132 constitute the third lens portion 133. The outer shape of the third annular portion 134 is D-shaped in the direction of the optical axis L. The gate mark G2 is formed when the second lens 12 is resin-molded. The gate mark G2 protrudes slightly radially outward from the flat portion 134a. In this case, the gate mark G2 is located inside the imaginary circle formed by the outer shape of the third annular portion 134. Flange surface 135 of third annular portion 134 facing object side La is located radially outside first lens surface 131. Flange surface 136 of third annular portion 134 facing image side Lb is located radially outside second lens surface 132.

[0028] The fourth lens 14 is a glass lens. The cemented lens 18 is a cemented lens made up of a fifth lens 15, which is a plastic lens having negative power, and a sixth lens 16, which is a plastic lens having positive power. The outer shape of the fifth lens 15 is D-shaped in the direction of the optical axis L. A gate mark G3 that protrudes slightly radially outward is left on a flat portion 15a of the outer peripheral surface of the fifth lens 15. The gate mark G3 is located inside a virtual circle formed by the outer shape of the fifth lens 15. The outer shape of the sixth lens 16 is D-shaped in the direction of the optical axis L. A gate mark G4 that protrudes slightly radially outward is left on a flat portion 16a of the outer peripheral surface of the sixth lens 16. The gate mark G4 is located inside a virtual circle formed by the outer shape of the sixth lens 16. Located to the side.

[0029] The lens unit 1 has an annular light-shielding sheet 2 between the second lens 12 and the third lens 13, and an annular diaphragm 3 between the fourth lens 14 and the fifth lens 15.

[0030] The first lens 11 has a larger outer diameter than the second lens 12, the third lens 13, the fourth lens 14, and the cemented lens 18. The second lens 12, the third lens 13, and the cemented lens 18 have approximately the same outer diameter, and in the cemented lens 18, the fifth lens 15 has a larger outer diameter than the sixth lens 16. The fourth lens 14 has a smaller outer diameter than the second lens 12, etc.

[0031] (lens barrel) FIG. 3 is a cross-sectional view of the lens barrel. FIG. 4 is a plan view of the lens barrel as viewed from the object side. The lens barrel 20 is made of resin. Materials used for the lens barrel 20 include crystalline plastics (polyethylene, polyamide, polytetrafluoroethylene) that are highly weather-resistant, and amorphous plastics (polycarbonate, etc.) that have relatively low moisture absorption. The lens barrel 20 is cylindrical. As shown in FIGS. 1 to 4, the lens barrel 20 includes a first cylindrical portion 21 that holds the first lens, a second cylindrical portion 22 that holds the second lens 12 and multiple lenses, and an outer cylindrical portion 23 that extends from the image side Lb of the first cylindrical portion 21. A ring-shaped recess 29 for reducing thickness is formed between the outer cylindrical portion 23 and the second cylindrical portion 22.

[0032] The lens barrel 20 also includes an abutment surface 24 that connects the first cylindrical portion 21 and the second cylindrical portion 22, and a positioning step 25 that projects radially inward from the inner circumferential surface of the second cylindrical portion 22.

[0033] The first tube portion 21 has a cylindrical shape and surrounds the outer peripheral surface of the first lens 11. A crimped portion 211 that fixes the first lens 11 is provided at the end of the first tube portion 21 on the object side La. The inner diameter of the first tube portion 21 is slightly larger than the outer diameter of the first lens 11.

[0034] The contact surface 24 is an annular surface facing the object side La. The contact surface 24 contacts the flange surface 115 of the first circular ring portion 114 from the image side Lb. The contact surface 24 has an annular groove 241 recessed toward the image side Lb. The second elastic member 32 is disposed in the groove 241.

[0035] The second tube portion 22 has a cylindrical shape. The inner diameter of the second tube portion 22 becomes slightly smaller toward the image side Lb. The second tube portion 22 includes a first portion 221 that holds the second lens 12 and a second portion 222 that holds multiple lenses. The first portion 221 surrounds the outer peripheral surface of the second lens 12. A recess 223 is provided on the inner peripheral surface of the first portion 221, with its open end facing the object side La. The recess 223 also serves as a gate mark accommodating recess that accommodates the gate mark G1. In this embodiment, the recesses 223 are provided in four locations at equal intervals in the circumferential direction.

[0036] A plurality of first ribs 224 are provided in the circumferential direction on the inner peripheral surface of the first portion 221. The first ribs 224 protrude radially inward and extend in the direction of the optical axis L. The first ribs 224 position the second lens 12 in the radial direction when the second lens 12 is press-fitted into the first portion 221. In this embodiment, the first ribs 224 are provided in four locations at equal intervals in the circumferential direction.

[0037] The second portion 222 surrounds the outer peripheral surfaces of the multiple lenses. A plurality of second ribs 225 are provided in the circumferential direction on the inner peripheral surface of the second portion 222. The second ribs 225 protrude radially inward and extend in the direction of the optical axis L. The second ribs 225 position the multiple lenses in the radial direction when the multiple lenses are press-fitted into the second portion 222. In this embodiment, the second ribs 225 are provided in 12 locations at equal intervals in the circumferential direction. Furthermore, the second ribs 225 are arranged in positions that do not overlap with the first ribs 224 in the direction of the optical axis L.

[0038] The positioning step 25 abuts against the cemented lens 18 (image-side lens) arranged closest to the image side from the image side Lb. The positioning step 25 has a protruding portion 251 that protrudes radially inward at the end on the image side Lb.

[0039] (Wide-angle lens fixed) Next, the fixation of the wide-angle lens 10 will be described. First, the cemented lens 18 to the second lens 12 are press-fitted into the second barrel portion 22. The cemented lens 18 is positioned in the optical axis L direction by the flange portion 150 of the fifth lens 15 abutting against the positioning step 25 from the object side La. The fourth lens 14 is held by the holder 4, and the holder 4 abuts against the flange portion 150 of the fifth lens from the object side La. The third annular portion 134 of the third lens 13 abuts against the holder 4 from the object side La via the diaphragm 3. The second lens 12 is press-fitted into the first portion 221 so that the gate mark G1 is located inside the recess 223. The second annular portion 124 of the second lens 12 abuts against the third annular portion 134 of the third lens 13 from the object side La via the light-shielding sheet 2. At this time, the flange surface 135 of the third annular portion 134 abuts against the flange surface 126 of the second annular portion 124 via the light blocking sheet 2, and is located on the object side La of the bottom surface 226 of the recess 223 on the image side Lb.

[0040] In this embodiment, four recesses 223 are provided at equal intervals in the circumferential direction. Therefore, if the center of second lens 12 is misaligned with optical axis L when second lens 12 is press-fitted into first portion 221, the center of second lens 12 can be aligned with optical axis L by rotating second lens 12 by 90° around optical axis L relative to first portion 221. After the center of second lens 12 is aligned with optical axis L, second lens 12 is press-fitted into first portion 221 such that gate mark G1 is located inside recess 223.

[0041] The first lens 11 is inserted into the first cylindrical portion 21. The first lens 11 is restricted from moving toward the object side La by the crimped portion 211 covering the object side La. As a result, the first lens 11 is held inside the first cylindrical portion 21. At this time, the flange surface 115 of the first annular portion 114 abuts against the abutment surface portion 24 from the object side La, and the first lens 11 is positioned in the direction of the optical axis L.

[0042] A first elastic member 31 is provided between the first annular portion 114 of the first lens 11 and the second annular portion 124 of the second lens 12. In this embodiment, the first elastic member 31 is an O-ring 310. The O-ring 310 is disposed on the outer circumferential side of the annular step portion 127. The O-ring 310 is positioned in the radial direction by the inner circumferential portion abutting against the annular step portion 127. When viewed from the direction of the optical axis L, the O-ring 310 overlaps with the positioning step portion 25. In a state where the O-ring 310 is elastically deformed in the direction of the optical axis L, it is in close contact with the flange surface 115 of the first lens 11 and the flange surface 125 of the second lens 12. At this time, the first lens 11 and the second lens 12 are not in contact with each other.

[0043] 1, a second elastic member 32 is provided outside O-ring 310 between flange surface 115 of first lens 11 and contact surface 24. Second elastic member 32 is O-ring 320. O-ring 320 is disposed in groove 241. O-ring 320 is in close contact with flange surface 115 of first lens 11 and the bottom surface of groove 241 in a state where it is elastically deformed in the direction of optical axis L.

[0044] Here, if the first holding force when the second lens 12 is fitted into the first portion 221 is f1, the number of lenses in the second lens 12 and the multiple lenses is C, the third holding force which is the sum of the first holding force and the second holding force when the multiple lenses are fitted into the second portion 222 is f2, the elastic force of the O-ring 310 is f3, and the fourth holding force with which the first cylindrical portion 21 holds the first lens 11 is f4, then the following conditional formula (1) is satisfied. f1×C < f2 < f3 < f4 (1)

[0045] If the fourth holding force f4 with which the first barrel portion 21 holds the first lens 11 is greater than the elastic force f3 of the O-ring 310, the elastic force f3 of the O-ring 310 will prevent the first lens 11 from coming off the first barrel portion 21, even if the lens unit 1 is used for a long period of time. As a result, even if the lens unit 1 is used for a long period of time, it is possible to prevent moisture that has passed through the O-ring 310 from entering the interior of the lens unit 1.

[0046] Furthermore, if the elastic force f3 is greater than a third holding force f2, which is the sum of the first holding force f1 when the second lens 12 is fitted into the first portion 221 and the second holding force when multiple lenses are fitted into the second portion 222, then when the first lens 11 is held in the first cylindrical portion 21 by crimping, the third holding force f2 can press the cemented lens 18 against the positioning step 25 via the second lens 12, etc. As a result, the cemented lens 18 can be reliably positioned by the positioning step 25.

[0047] Furthermore, when the third holding force f2 is greater than the first holding force f1 times the number of lenses C, the first holding force f1 becomes smaller than the average holding force obtained by dividing the second holding force when multiple lenses are fitted in the second portion 222 by the number of lenses C. Therefore, when the first lens 11 is held in the first cylindrical portion 21 by crimping, a large force is unlikely to be applied to the second lens 12, and the second lens 12 is unlikely to be distorted. As a result, the O-ring 310 can be evenly tightly attached between the first lens 11 and the second lens 12, so that moisture that has passed through the O-ring 310 can be prevented from entering the interior of the lens unit 1 even when the lens unit 1 is used for a long period of time.

[0048] In this embodiment, the first holding force f1 when the second lens 12 is fitted into the first portion 221 is 3 N. The second lens 12 and the multiple lenses are the second lens 12, the third lens 13, the fourth lens, and the cemented lens 18, and the number of lenses C is four. The third holding force f2, which is the sum of the first holding force and the second holding force when the multiple lenses are fitted into the second portion 222, is 20 N. The elastic force f3 of the O-ring 310 is 30 N. The fourth holding force f4 with which the first cylindrical portion 21 holds the first lens 11 is 250 N. Therefore, conditional formula (1) is satisfied.

[0049] (Action and effect) In this embodiment, the second lens 12 includes a second annular portion 124, a portion on the outer circumferential surface of which a gate mark G1 remains. The inner circumferential surface of the first portion 221 includes a recess 223, the gate mark G1 being located inside, with its open end facing the object side La. Because the gate mark G1 is accommodated in the recess 223, it is not necessary to form the gate mark G1 on a flat portion of the outer circumferential surface of the second annular portion 124. In other words, it is not necessary to provide a flat portion on the outer circumferential surface of the second annular portion 124, and the outer diameter shape of the second annular portion 124 remains circular. Therefore, compared to when the gate mark is formed on a flat portion of the outer circumferential surface of the lens, a larger contact area with the first elastic member 31 can be ensured. As a result, airtightness between the first lens 11 and the second lens 12 can be ensured, thereby suppressing fogging of the first lens 11.

[0050] In this embodiment, the first elastic member 31 is compressed between the first annular portion 114 and the second annular portion 124 to an extent that the first lens 11 and the second lens 12 do not come into contact with each other. Therefore, it is easier to manage the amount of compression of the first elastic member 31 compared to when the first lens 11 and the second lens 12 come into contact with each other. As a result, it is easy to increase the airtightness inside the lens barrel 20, and it is possible to prevent the lens surface on the image side of the first lens 11 from fogging up. In addition, because the first lens 11 and the second lens 12 do not come into contact with each other, when the first lens 11 is held in the first tube portion 21, the first elastic member 31 is compressed, and the second lens 12 and the multiple lenses 12, ... A large force is unlikely to be applied directly to the lens, and therefore, when the first lens 11 is held in the first barrel portion 21, damage to the second lens 12 and subsequent lenses can be prevented.

[0051] In this embodiment, four recesses 223 are provided at equal intervals in the circumferential direction. Therefore, if the center of second lens 12 is misaligned with optical axis L when second lens 12 is press-fitted into first portion 221, the center of second lens 12 can be aligned with optical axis L by rotating second lens 12 by 90° around optical axis L relative to first portion 221.

[0052] In this embodiment, the second annular portion 124 includes an annular step portion 127 that protrudes toward the object side La and that can position the first elastic member 31 in the radial direction. This makes it easy to position the first elastic member 31 in the radial direction. As a result, it is possible to prevent a lack of airtightness between the first lens 11 and the second lens 12 due to misalignment of the first elastic member 31.

[0053] In this embodiment, the third lens 13, which is adjacent to the second lens 12 on the image side among the multiple lenses, includes a third lens portion 133 and a third annular portion 134 that surrounds the third lens portion 133. A flange surface 135 facing the object side of the third annular portion 134 abuts against a flange surface 126 facing the image side Lb of the second annular portion 124 in the direction of the optical axis L, and is located on the object side La of the bottom surface 226 on the image side Lb of the recess 223. Therefore, the gate mark G1 does not come into contact with the bottom surface 226 of the recess 223, and the third lens 13 can reliably position the second lens 12.

[0054] In this embodiment, a plurality of first ribs 224 that position the second annular portion 124 in the radial direction are provided circumferentially on the inner peripheral surface of the first portion 221. Therefore, even if distortion is likely to occur due to the external shape of the lens barrel 20, the first ribs 224 can prevent misalignment of the second lens 12 caused by distortion of the first portion 221.

[0055] In this embodiment, the lens barrel 20 has an abutment surface 24 that abuts against the first annular portion 114 from the image side Lb, between the first tube portion 21 and the second tube portion 22. The abutment surface 24 has an annular groove 241 that is recessed toward the image side Lb. An annular second elastic member 32 is disposed in the groove 241 and compressed between the first annular portion 114 and the groove 241. This makes it easier to ensure airtightness between the first lens 11 and the second lens 12.

[0056] In this embodiment, the second cylindrical portion 22 includes a second portion 222 that holds multiple lenses. A plurality of second ribs 225 that position the multiple lenses in the radial direction are provided circumferentially on the inner peripheral surface of the second portion 222. Therefore, even if distortion is likely to occur due to the external shape of the lens barrel 20, the second ribs 225 can prevent misalignment of the multiple lenses caused by distortion of the second portion 222.

[0057] In this embodiment, the lens barrel 20 includes a positioning step 25 that abuts, from the image side Lb, on the cemented lens 18 that is arranged closest to the image side among the multiple lenses. The first elastic member 31 overlaps with the positioning step 25 in the direction of the optical axis L. Therefore, the force in the direction of the optical axis L when the first elastic member 31 is compressed by the first lens 11 is concentrated on the positioning step 25. This makes it possible to prevent distortion of the lens barrel 20 when the first lens 11 is attached. [Explanation of symbols]

[0058] 1...lens unit, 2...light blocking sheet, 3...diaphragm, 4...holder, 10...wide-angle lens, 11...first lens, 12...second lens, 13...third lens, 14...fourth lens, 15...fifth lens, 15a...flat portion, 16...sixth lens, 16a...flat portion, 18...cemented lens, 20...lens barrel, 21...first cylindrical portion, 22...second cylindrical portion, 23...outer cylindrical portion, 24...contact surface portion, 25...positioning step portion, 29...recess, 31...first elastic member, 32...second elastic member, 111...first lens surface, 112...second lens surface, 113...first lens portion, 114...first annular portion, 115...flange surface, 121...first lens surface, 122...second lens surface, 123...second lens portion, 124...second annular portion, 125...flange surface, 126...flange surface, 127...annular step portion, 131...first lens surface, 132...second lens surface, 133...third lens portion, 134...third annular portion, 134a...flat portion, 135...flange surface, 136...flange surface, 150...flange portion, 211...crimped portion, 221...first portion, 222...second portion, 223...recess, 224...first rib, 225...second rib, 226...bottom surface, 241...groove portion, 251...projection portion, 310...ring, 320...ring, G1 to G4...gate marks, L...optical axis, La...object side, Lb...image side

Claims

1. a first lens arranged closest to the object along the optical axis; a second lens made of resin and arranged on the image side of the first lens; a plurality of lenses arranged on the image side of the second lens; a lens barrel that holds the first lens, the second lens, and the plurality of lenses; a first annular elastic member disposed between the first lens and the second lens; and the first lens includes a first lens portion and a first annular portion that surrounds the first lens portion, the second lens includes a second lens portion and a second annular portion that surrounds the second lens portion and has a gate mark remaining on an outer peripheral surface thereof, the lens barrel includes a first cylindrical portion that holds the first lens, and a second cylindrical portion that is radially inward of the first cylindrical portion and holds the second lens and the plurality of lenses, the second cylindrical portion includes a cylindrical first portion that holds the second lens; a gate mark accommodating recess, the gate mark being located inside, is provided on an inner circumferential surface of the first portion, with an open end facing the object side; the first elastic member is compressed between the first annular portion and the second annular portion to such an extent that the first lens and the second lens do not come into contact with each other; a third lens among the plurality of lenses adjacent to the second lens on the image side includes a third lens portion and a third annular portion that surrounds the third lens portion; a surface of the third annular portion facing the object side abutting the surface of the second annular portion facing the image side in the optical axis direction, and being located closer to the object side than the image-side bottom surface of the gate mark accommodating recess.

2. 2. The lens unit according to claim 1, The second lens is a lens unit having an annular step portion that protrudes toward the object side at the second annular portion and is capable of positioning the first elastic member in a radial direction.

3. 2. The lens unit according to claim 1, A lens unit comprising a light-shielding sheet disposed between the second lens and the third lens.

4. The lens unit according to any one of claims 1 to 3, A lens unit characterized in that first ribs for positioning the second lens in a radial direction are provided at a plurality of locations in the circumferential direction on an inner peripheral surface of the first portion.

5. The lens unit according to any one of claims 1 to 4, the lens barrel includes a contact surface portion that contacts the first annular portion from an image side between the first cylindrical portion and the second cylindrical portion, the abutment surface portion includes an annular groove portion recessed toward the image side, The lens unit according to claim 1, wherein a second annular elastic member is disposed in the groove and compressed between the first annular portion and the groove.

6. The lens unit according to any one of claims 1 to 5, the second tube portion includes a second portion that holds the plurality of lenses; The lens unit is characterized in that second ribs for positioning the lenses in the radial direction are provided at multiple locations on the inner peripheral surface of the second portion.

7. 7. The lens unit according to claim 1, the lens barrel includes a positioning step portion that abuts, from the image side, on an image-side lens that is arranged closest to the image side among the plurality of lenses, The lens unit is characterized in that the first elastic member overlaps the positioning step portion in the optical axis direction.

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