Lens barrel, mold, and method for manufacturing lens barrel

Abstract

To further improve positioning accuracy of a lens than a prior art.SOLUTION: A lens barrel for holding a lens therein includes a part for positioning the lens, wherein a position of a weld line formed by joining a resin injected into a mold of the lens barrel is positioned at least a position excluding a decentered position in a circumferential direction of the lens barrel of the positioning part.SELECTED DRAWING: Figure 12

Description

[Technical field]

[0001] The technology disclosed herein relates to a lens barrel, a mold, and a method for manufacturing the lens barrel. [Background technology]

[0002] Patent Document 1 discloses a lens barrel in which a lens group is assembled. Inside this lens barrel, a positioning portion is formed for positioning the assembled lens in the radial direction and the axial direction. Such a lens barrel is molded into a generally cylindrical shape by injecting molten resin into a mold for the lens barrel through two or more gates spaced apart from each other in the circumferential direction.

[0003] In the lens barrel, the position of a weld line formed by the joining of the injected resin is located at the positioning portion. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2022-027669 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, if the weld line is located at the circumferential center of the positioning portion as described above, the lens cannot be positioned at a desired position, which deteriorates the positioning accuracy of the lens. The technology disclosed herein has been developed in consideration of the above-mentioned facts, and aims to provide a lens barrel, a mold, and a method for manufacturing a lens barrel that can improve the lens positioning accuracy compared to conventional techniques. [Means for solving the problem]

[0006] A first aspect of the technology disclosed herein for achieving the above-mentioned object is a lens barrel for holding a lens therein, comprising a portion for positioning the lens, and a weld line formed by the joining of resin injected into a mold for the lens barrel is located at a position that is at least off-center of the circumferential direction of the lens barrel of the positioning portion.

[0007] A second aspect is a mold for the lens barrel of the first aspect, which is provided with an inlet for injecting the resin, and the position of the inlet for injecting the resin is determined so that the position of a weld line formed by the joining of the injected resin is located at a position off-center in the circumferential direction of the portion that positions the lens.

[0008] A third aspect is a mold for the lens barrel of the first aspect, which is provided with multiple inlets for injecting the resin, and the sizes of the multiple inlets are determined so that the position of a weld line formed by the joining of the injected resin is located at a position off-center in the circumferential direction of the portion that positions the lens.

[0009] A fourth aspect is a method for manufacturing the lens barrel of the first aspect, comprising: a mold for the lens barrel, the mold having a plurality of inlets for injecting the resin; and the resin is injected into the plurality of inlets so that a weld line formed by the joining of the resin injected into the mold for the lens barrel is positioned at a position off the circumferential center of the portion to be positioned.

[0010] A fifth aspect is a lens barrel comprising a first lens barrel and a second lens barrel held on the inner periphery of the first lens barrel and for holding a lens inside, wherein the inner surface of the second lens barrel has a portion for positioning the lens, and the lens barrel is manufactured by injecting resin into a portion of the mold for manufacturing the lens barrel corresponding to the first lens barrel and then into a portion corresponding to the second lens barrel, and the position of a weld line formed by the joining of resin injected into the mold is located at a position at least off-center of the circumferential direction of the lens barrel of the positioning portion. Effect of the Invention

[0011] The technique of the present disclosure can improve the lens positioning accuracy as compared to conventional techniques. [Brief description of the drawings]

[0012] [Figure 1] 1 is a perspective view of the appearance of a lens unit to which the present invention is applied; [Diagram 2] FIG. 2 is a cross-sectional view of the lens unit. [Diagram 3] FIG. 2 is an exploded perspective view of the lens unit. [Figure 4] FIG. 2 is an exploded perspective view of a lens L3 and a lens L4 as viewed from the object side. [Diagram 5] FIG. 2 is an exploded perspective view of the lens L3 and the lens L4 as viewed from the image side. [Figure 6] FIG. 2 is an exploded perspective view of a lens L5 and a lens L6 as viewed from the object side. [Figure 7] FIG. 2 is an exploded perspective view of lenses L5 and L6 as viewed from the image side. [Figure 8] 13 is a perspective view of the holder, lens L5, and lens L6. [Figure 9] FIG. 4 is a cross-sectional view of the first lens barrel. [Figure 10] FIG. 2 is a perspective view of the second lens barrel as viewed from the object side. [Figure 11] FIG. 4 is a cross-sectional view of the second lens barrel. [Figure 12] 11 is a diagram showing the relationship between the position of a weld line formed in the second barrel and the position of a rib that positions the lens. FIG. [Figure 13] 11A and 11B are diagrams showing the positions of pin gate marks formed on the lens barrel. [Figure 14] FIG. 2 is a block diagram of a lens barrel manufacturing apparatus. [Figure 15] 13 is a flowchart showing a lens barrel manufacturing processing program. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a lens unit to which the present invention is applied will be described with reference to the drawings.

[0014] (optical system) FIG. 1 is an external perspective view of a lens unit to which the present invention is applied. FIG. 2 is a cross-sectional view of the lens unit. FIG. 3 is an exploded perspective view of the lens unit. FIG. 4 is an exploded perspective view of lenses L3 and L4 when viewed from the object side. FIG. 5 is an exploded perspective view of lenses L3 and L4 when viewed from the image side. FIG. 6 is an exploded perspective view of lenses L5 and L6 when viewed from the object side. FIG. 7 is an exploded perspective view of lenses L5 and L6 when viewed from the image side. FIG. 8 is a perspective view of a holder, lens L5, and lens L6. Note that in FIG. 2, the shapes of the lenses in the area between the two dashed double-dashed lines (around the optical axis) are omitted.

[0015] The lens unit 1 of this example shown in FIG. 1 is used in an imaging device mounted on an automobile or a surveillance camera. As shown in FIG. 2, the lens unit 1 includes, from the object side to the image side, a lens L1, a lens L2, a lens L3, a lens L4, a lens L5, and a lens L6 in this order. The lens L6 is a cemented lens, and includes, from the object side to the image side, an object side lens L61 and an image side lens L62 in this order. The lens unit 1 also includes, as the lens barrel 2, a first lens barrel 3 and a second lens barrel 4 held on the inner periphery side of the first lens barrel 3. The lens L1 is housed in the first lens barrel 3. The lenses L2 to L6 are housed in the second lens barrel 4. The second lens barrel 4 is held on the inner periphery side of the first lens barrel 3.

[0016] 3, the lens L1 and the first barrel 3 constitute a first unit 50. The lenses L2 to L6 and the second barrel 4 constitute a second unit 60. In the following, the direction along the optical axis L of the lens L1 is referred to as the optical axis direction X. The optical axis L of the lens L1 is the optical axis L of the lens unit 1. The object side X1 in the optical axis direction X is the side where the lens L1 is located, and the image side X2 is the side where the lens L6 is located.

[0017] As shown in FIG. 2, lens L1 has a larger outer diameter than lenses L2 to L6. In this example, lens L1 is made of glass. Lens L1 is a meniscus lens having a convex shape on the object side X1. Lens L1 has an annular end face 11 that expands in a direction perpendicular to the optical axis L on the outer periphery of the lens surface on the image side X2. A first O-ring 7 is disposed on the image side X2 of the end face 11 of lens L1.

[0018] The lens L2 is made of resin. The lens L2 includes a lens body 13 having a lens surface, and a flange 14 surrounding the lens body 13. The lens L2 is a meniscus lens having a convex shape on the object side X1. An annular protrusion 15 that protrudes toward the object side X1 is provided on the end face of the flange 14 on the object side X1. The tip of the annular protrusion 15 is an annular contact portion 15a that comes into surface contact with the end face of the lens L1.

[0019] As shown in FIG. 2, FIG. 4, and FIG. 5, the lens L3 is made of resin. The lens L3 includes a lens body 16 having a lens surface, and a flange 17 surrounding the lens body 16. The lens L3 is a meniscus lens having a convex shape on the image side X2. As shown in FIG. 5, an annular fitting portion 18 protruding to the image side X2 is provided on the end surface of the flange 17 on the image side X2. The fitting portion 18 includes a fitting portion tapered surface 18a surrounding the optical axis L and inclining toward the inner periphery toward the image side X2, and a fitting portion end surface 18b extending perpendicular to the optical axis L from the end of the fitting portion tapered surface 18a on the image side X2 toward the inner periphery.

[0020] Here, as shown in FIG. 2, an elastic member is disposed between the lens L2 and the lens L3 in the optical axis direction X. The elastic member is a second O-ring 8. The second O-ring 8 is compressed in the optical axis direction X between the flange portion 14 of the lens L2 and the flange portion 17 of the lens L3. In this example, a resin light-shielding sheet 9 is disposed between the lens L2 and the lens L3 in the optical axis direction X. The light-shielding sheet 9 is annular. The second O-ring 8 is located between the light-shielding sheet 9 and the lens L3.

[0021] The lens L4 is made of resin. As shown in Fig. 2, Fig. 4 and Fig. 5, the lens L4 includes a lens body 20 having a lens surface, and a flange 21 surrounding the lens body 20. The lens surface on the object side X1 of the lens body 20 of the lens L4 is a curved surface that protrudes to the object side X1. The lens surface on the image side X2 of the lens body 20 includes a curved surface portion at the center that protrudes to the image side X2.

[0022] As shown in Fig. 4, the end face of the flange portion 21 on the object side X1 is provided with a fitted portion 22 into which the fitting portion 18 of the lens L3 fits. The fitted portion 22 includes a fitted portion tapered surface 22a that surrounds the optical axis L and inclines inward toward the image side X2, and a fitted portion end face 22b that extends perpendicular to the optical axis L from the end of the fitted portion tapered surface 22a on the image side X2 toward the inner periphery. As shown in Fig. 2, the fitted portion tapered surface 18a of the lens L3 and the fitted portion tapered surface 22a of the lens L4 are in surface contact. The fitted portion end face 18b of the lens L3 and the fitted portion end face 22b of the lens L4 are separated in the optical axis direction X. In this example, an end face on the image side X2 of the outer peripheral portion of the fitting portion 18 of the flange portion 17 of the lens L3 and an end face on the object side X1 of the outer peripheral portion of the fitted portion 22 of the flange portion 21 of the lens L4 come into contact in the optical axis direction X. As a result, the lens L3 is placed on the lens L4, and the lens L3 is positioned in the optical axis direction X.

[0023] The lens L5 is made of glass. As shown in FIG. 2, the lens L5 has an outer diameter smaller than the lens L2, the lens L3, the lens L4, and the lens L6. The lens L5 has a lens body 24 having a lens surface and a flange 25 surrounding the lens body 24. The lens L5 is a biconvex lens. As shown in FIG. 2 and FIG. 7, the image side X2 of the flange 25 is a contact portion 26 that contacts the lens L6 from the object side X1. The cross section of the contact portion 26 cut along the optical axis L is an arc that curves toward the object side X1 toward the outer periphery. As shown in FIG. 7, the surface of the image side X2 of the contact portion 26 is continuous with the outer periphery end of the lens surface 24a of the image side X2 of the lens body 24 without any step.

[0024] As shown in FIG. 2, a resin holder 28 is disposed on the radial outside of the lens L5. As shown in FIG. 8, the holder 28 is annular. The holder 28 includes a central portion 29 adjacent to the lens L5 with a gap 28a in the radial direction, and an outer peripheral portion 30 that is on the outer peripheral side of the central portion 29 and is thicker in the optical axis direction X than the central portion 29. The surface of the central portion 29 on the object side X1 inclines from the outer peripheral portion 30 toward the image side X2 toward the inner peripheral side. The central portion 29 and the outer peripheral portion 30 are provided with cutout portions 31 cut out from the object side X1 and the inner peripheral side at three locations in the circumferential direction. The bottom surface of the cutout portion 31 (the surface facing the object side X1) is continuous with the edge on the inner peripheral side of the central portion 29.

[0025] Here, an aperture 33 is disposed between the lens L4 and the lens L5. The aperture 33 is an annular sheet, and is sandwiched between the lens L4 and the holder 28 and supported at a predetermined position in the optical axis direction X.

[0026] The lens L6 is made of resin. That is, both the object-side lens L61 and the image-side lens L62 are made of resin. As shown in FIG. 2, the object-side lens L61 includes a lens body 35 having a lens surface and a flange 36 surrounding the lens body 35. The lens surface on the object side X1 of the object-side lens L61 is a curved surface that curves toward the image side X2, and the lens surface on the image side X2 is a curved surface that is recessed toward the object side X1.

[0027] As shown in Fig. 6, the flange portion 36 of the object-side lens L61 has a contacted portion 37 on the object side X1 with which the contact portion 26 of the lens L5 comes into contact. The contacted portion 37 is a tapered surface extending toward the object side X1 toward the outer periphery. The contact portion 26 and the contacted portion 37 are in line contact. The contact line M where the contact portion 26 and the contacted portion 37 come into contact is annular and coaxial with the optical axis L, and is located on a virtual vertical plane perpendicular to the optical axis L. In addition, the flange portion 36 of the object-side lens L61 has an annular end face 38 perpendicular to the optical axis L on the image side X2.

[0028] The image-side lens L62 includes a lens body 40 having a lens surface and a flange 41 surrounding the lens body 40. The lens surface on the object side X1 of the image-side lens L62 is a curved surface protruding toward the object side X1, and the lens surface on the image side X2 is a curved surface protruding toward the image side X2. The image-side lens L62 is fixed to the object-side lens L61. The outer diameter of the image-side lens L62 is smaller than the outer diameter of the object-side lens L61. Therefore, as shown in FIG. 7, when viewed from the image side X2, the flange 36 of the object-side lens L61 includes a portion that protrudes from the image-side lens L62 toward the outer periphery.

[0029] Here, as shown in Fig. 2, the lens L5 is stacked on the lens L6. Furthermore, the lens L4 is stacked on the lens L6 via the holder 28. The lens L4, the holder 28, the lens L5, and the lens L6 configure a laminate 44. The lens L3 is stacked on the lens L4. That is, the lens L3 is stacked in the laminate 44. Furthermore, a plate-shaped cover 10 is disposed on the image side X2 of the lens L6.

[0030] (Telescope tube) As shown in FIGS. 2 and 3, the lens unit 1 includes a lens barrel 2, which is a first lens barrel 3 and a second lens barrel 4 held on the inner periphery side of the first lens barrel 3. Both the first lens barrel 3 and the second lens barrel 4 are made of resin. The first lens barrel 3 and the second lens barrel 4 are resin injection molded products formed by injecting resin into a metal mold. The lens L1 is accommodated in the first lens barrel 3. The lenses L2 to L6 and the holder 28 are accommodated in the second lens barrel 4. The second lens barrel 4 is held on the inner periphery side of the first lens barrel 3.

[0031] (First lens barrel and lens L1) 9 is a cross-sectional view of the first lens barrel 3. The first lens barrel 3 has a cylindrical shape and is located on the outer circumferential side of the lens L2, lens L3, lens L4, holder 28, lens L5, lens L6, and second lens barrel 4. As shown in FIG. 3 and FIG. 9, the first lens barrel 3 has an object side step 101 at an end portion on the object side X1 of the inner circumferential surface, and an image side step 102 at an end portion on the image side X2. The first lens barrel 3 also has an intermediate step 103 between the object side step 101 and the image side step 102 in the optical axis direction X of the inner circumferential surface.

[0032] The object-side step 101 includes a support surface 105 facing the object side X1, an annular wall surface 106 extending from an inner peripheral end of the support surface 105 to the image side X2 and facing radially inward, and a peripheral wall surface 107 extending from an outer peripheral end of the support surface 105 to the object side X1. In the first lens barrel 3, the object side X1 of the object-side step 101 is a housing portion 108 that houses an outer peripheral edge portion of the lens L1. The second lens barrel 4 is disposed on the inner peripheral side of the annular wall surface 106.

[0033] The housing portion 108 includes a peripheral wall surface 107, a support surface 105, and a crimped portion 109. As shown in FIG. 2, the peripheral wall surface 107 faces the lens L1 from the radial outside. The support surface 105 faces the end surface 11 of the lens L1 from the image side X2. The crimped portion 109 abuts against the lens L1 from the object side X1 at a position overlapping with the support surface 105 when viewed from the optical axis direction X along the optical axis L of the lens L1. The crimped portion 109 is a plastic deformation portion provided by thermal crimping or the like that bends the end portion of the object side X1 of the first barrel 3 toward the inner periphery side. Here, the outer peripheral edge portion of the lens L1 is disposed between the support surface 105 and the crimped portion 109. The first O-ring 7 is disposed between the end surface of the image side X2 of the lens L1 and the support surface 105, and is compressed in the optical axis direction X.

[0034] 3, the annular wall surface 106 is provided with object-side protrusions 110 that protrude radially inward at multiple locations in the circumferential direction. In this example, the object-side protrusions 110 are provided at three locations in the circumferential direction, equiangularly spaced apart. The object-side protrusions 110 are object-side positioning portions for positioning the second lens barrel 4 in the radial direction.

[0035] As shown in Fig. 3 and Fig. 10, the image side step 102 includes an annular image side end face 112 facing the object side X1, and an annular image side inner wall surface 113 extending from the inner peripheral end of the image side end face 112 to the image side X2 and reaching the end of the image side X2 of the first lens barrel 3. The image side end face 112 is provided with a plurality of ribs 114 that protrude to the object side X1 and extend in an arc shape in the circumferential direction. In this example, the ribs 114 are provided at three positions in the circumferential direction at equal angular intervals. The ribs 114 are image side positioning portions for positioning the second lens barrel 4 in the optical axis direction X.

[0036] The intermediate step 103 includes an annular step end surface 116 facing the object side X1, and an annular step wall surface 117 extending from the inner peripheral end of the step end surface 116 to the image side X2. In this example, the intermediate step 103 is provided with notched grooves 118 at multiple locations in the circumferential direction, which extend in the optical axis direction X and divide the step end surface 116 and the step wall surface 117 in the circumferential direction. In this example, the notched grooves 118 are provided at three locations in the circumferential direction at equal angular intervals. Therefore, the intermediate step 103 is divided into three in the circumferential direction by the notched grooves 118. The bottom surface (surface facing the inner peripheral side) of the notched groove 118 is a tapered surface, and the inner diameter dimension becomes smaller toward the image side X2. As shown in FIG. 2, the bottom surface of the notched groove 118 is continuous with an inner peripheral surface portion of the first barrel 3 that extends from the outer peripheral end of the image-side end face 112 of the image-side step 102 toward the object side X1.

[0037] 3, the notched groove 118 is provided at the same angular position as the rib 114 of the image side step 102. The notched groove 118 is also provided at the same angular position as the object side protrusion 110 of the object side step 101. When connecting the first lens barrel 3 and the second lens barrel 4 arranged on the inner peripheral side of the first lens barrel 3, an adhesive is applied to each step end face 116 of the intermediate step 103 divided into three. As a result, a lens barrel connecting adhesive layer 51 is provided on the step end faces 116 and the step wall faces 117.

[0038] (Second lens barrel and lenses L2 to L6) Fig. 10 is a perspective view of the second lens barrel 4 as viewed from the object side. Fig. 11 is a cross-sectional view of the second lens barrel 4. The area surrounded by the chain line in Fig. 11 is a partially enlarged view of the periphery of the fitting protrusion 210. The second lens barrel 4 houses lenses L2, L3, L4, L5, holder 28, and L6 on its inner periphery.

[0039] 10 and 11, the second lens barrel 4 has an object-side step 201 at an end portion on the object side X1 of its inner circumferential surface. The second lens barrel 4 also has an image-side step 202 at an end portion on the image side X2. The second lens barrel 4 further has a positioning step 203 between the object-side step 201 and the image-side step 202, closer to the image-side step 202 than the object-side step 201. The second lens barrel 4 also has a cover holder 204 that holds the cover 10 at the end portion on the image side X2.

[0040] 11, the object-side step 201 includes a seating surface 205 facing the object side X1, an annular wall surface 206 extending from an inner peripheral end of the seating surface 205 to the image side X2, and a peripheral wall surface 207 extending from an outer peripheral end of the seating surface 205 to the object side X1. The annular wall surface 206 is a tapered surface whose inner diameter dimension increases toward the object side X1. In the second barrel 4, the object side X1 of the object-side step 201 is a housing portion 208 that houses an outer peripheral edge portion of the lens L2.

[0041] The housing portion 208 includes a peripheral wall surface 207, a seating surface 205, and a crimping portion 209. As shown in Fig. 2, the peripheral wall surface 207 faces the lens L2 from the radially outer side. The seating surface 205 faces an end surface of the flange portion 14 of the lens L2 on the image side X2 from the image side X2. The crimping portion 109 abuts against the lens L2 from the object side X1 at a position overlapping with the seating surface 205 when viewed from the optical axis direction X.

[0042] As shown in FIG. 10, the peripheral wall surface 207 is a tapered surface that inclines from the seat surface 205 toward the object side X1 toward the outer periphery. The peripheral wall surface 207 has fitting protrusions 210A that are pressed against the lens L2 at multiple locations spaced apart in the circumferential direction. In this example, the fitting protrusions 210A are provided at eight locations in the circumferential direction at equal angular intervals. The fitting protrusions 210A have a pressure-bonding surface 210a parallel to the optical axis L at the end on the inner periphery side. The fitting protrusions 210A also have a curved surface 210b that curves from the pressure-bonding surface 210a toward the object side X1 toward the outer periphery side. The pressure-bonding surfaces 210a of the multiple fitting protrusions 210A are pressed against the lens L2 accommodated in the accommodation portion 208 from the radially outer side, thereby positioning the lens L2 in the radial direction.

[0043] As shown in Fig. 11, the image side step portion 202 includes an annular image side end face 212 facing the object side X1, and an image side inner wall surface 213 extending from an inner peripheral end of the image side end face 212 to the image side X2. The image side inner wall surface 213 is a tapered surface inclined toward the outer peripheral side toward the image side X2. As shown in Fig. 2, the image side end face 212 faces the image side lens L62 of the lens L6 with a gap therebetween in the optical axis direction X. The cover holding portion 204 is provided on the outer peripheral side of the image side inner wall surface 213.

[0044] As shown in FIGS. 10 and 11, the positioning step 203 includes an annular positioning surface 215 facing the object side X1, and a positioning step peripheral wall surface 216 extending from an inner peripheral end of the positioning surface 215 to the image side X2. The positioning surface 215 is provided with a plurality of positioning ribs 217 that protrude toward the object side X1 and extend in an arc shape in the circumferential direction. In this example, the positioning ribs 217 are provided at three positions in the circumferential direction at equal angular intervals. The lower end of the positioning step peripheral wall surface 216 reaches the image side end surface 212 of the image side end surface 212. The positioning step peripheral wall surface 216 faces the image side lens L62 of the lens L6 with a gap therebetween in the radial direction.

[0045] 2, the positioning rib 217 is a positioning portion that abuts against the flange portion 36 of the object-side lens L61 of the lens L6 from the image side X2 to position the lens L6 in the optical axis direction X. Here, the flange portion 36 of the object-side lens L61 of the lens L6 abuts against the positioning portion, so that the laminate 44 including the lens L4, holder 28, lens L5, and lens L6 and the lens L3 are positioned in the optical axis direction X.

[0046] More specifically, the holder 28 is supported from the image side X2 by the lens L6, and is positioned at a predetermined position in the optical axis direction X. The lens L4 is supported from the image side X2 by the holder 28, and is positioned at a predetermined position in the optical axis direction X. The lens L5 is positioned in the optical axis direction X and the radial direction by contacting the lens L6. The lens L3 is positioned in the optical axis direction X and the radial direction by fitting into the lens L4. Here, when the lens L5 is positioned in the optical axis direction X and the radial direction, the lens L5 and the holder 28 do not come into contact with each other. When the lens L3 and the lens L4 are positioned in the optical axis direction X and the radial direction, the lens L3 and the second barrel 4 do not come into contact with each other. The lens L3, the lens L4, the holder 28, and the lens L5 are positioned between the object side step 201 and the positioning step 203 in the optical axis direction X.

[0047] As shown in FIG. 10 and FIG. 11, on the inner peripheral surface of the second lens barrel 4, an inner peripheral surface portion 4a located radially outside the object-side lens L61 of the lens L6 is a tapered surface that inclines toward the outer peripheral side toward the object side X1. The inner peripheral surface portion 4a has ribs (fitting protrusions) 210B that are pressed against the lens L6 at multiple locations spaced apart in the circumferential direction. The ribs 210B are provided at eight locations in the circumferential direction at equal angular intervals. The ribs 210B have a pressing surface 210a parallel to the optical axis L at the end on the inner peripheral side. The ribs 210B also have a curved surface 210b that curves from the pressing surface 210a toward the outer peripheral side toward the object side X1. The pressing surfaces 210a of the multiple ribs 210B are pressed against the lens L6 housed in the second lens barrel 4 from the radially outer side to position the lens L6 in the radial direction.

[0048] In addition, on the inner peripheral surface of the second barrel 4, an inner peripheral surface portion 4b located on the radially outer side of the holder 28 is a tapered surface that inclines toward the outer peripheral side toward the object side X1. The inner peripheral surface portion 4b has fitting protrusions 210C that are pressed against the lens L6 at multiple locations spaced apart in the circumferential direction. The fitting protrusions 210C are provided at six locations in the circumferential direction at equal angular intervals. The fitting protrusions 210C have a pressure-bonding surface 210a parallel to the optical axis L at the end on the inner peripheral side. The fitting protrusions 210C also have a curved surface 210b that curves from the pressure-bonding surface 210a toward the outer peripheral side toward the object side X1. The pressure-bonding surfaces 210a of the multiple fitting protrusions 210C are pressed against the holder 28 housed in the second barrel 4 from the radially outer side to position the holder 28 in the radial direction.

[0049] Furthermore, on the inner peripheral surface of the second barrel 4, an inner peripheral surface portion 4c located radially outside the lens L4 is a tapered surface that inclines toward the outer peripheral side toward the object side X1. The inner peripheral surface portion 4c has fitting protrusions 210D that are pressed against the lens L4 at multiple locations spaced apart in the circumferential direction. The fitting protrusions 210D are provided at six locations in the circumferential direction at equal angular intervals. The fitting protrusions 210D have a pressure-bonding surface 210a parallel to the optical axis L at the end on the inner peripheral side. The fitting protrusions 210D also have a curved surface 210b that curves from the pressure-bonding surface 210a toward the outer peripheral side toward the object side X1. The pressure-bonding surfaces 210a of the multiple fitting protrusions 210D press against the lens L4 housed in the second barrel 4 from the radially outer side to position the lens L4 in the radial direction.

[0050] In addition, on the inner peripheral surface of the second lens barrel 4, an inner peripheral surface portion 4d located on the radially outer side of the lens L3 is a tapered surface that inclines toward the outer peripheral side toward the object side X1. The inner peripheral surface portion 4d located on the radially outer side of the lens L3 is continuous without any step with the image side X2 of the annular wall surface 206 of the object side step portion 201. The inner peripheral surface portion 4d has guide protrusions 220 that guide the lens L3 in the optical axis direction X at multiple locations spaced apart in the circumferential direction. The guide protrusions 220 are provided at eight locations in the circumferential direction at equal angular intervals. The guide protrusions 220 have a guide surface 220a parallel to the optical axis L at the end on the inner peripheral side. In addition, the guide protrusions 220 have a curved surface 220b that curves from the pressure-bonding surface 210a toward the outer peripheral side toward the object side X1. When the lens L3 is fitted into the lens L4, the guide protrusions 220 are located radially outside the lens L3, but do not come into contact with the lens L3. The guide surfaces 220a of the guide protrusions 220 face the lens L3 with a small radial gap therebetween.

[0051] Here, the second O-ring 8 is disposed on the object side X1 of the multiple guide protrusions 220, radially inside the annular wall surface 206 of the object-side step portion 201. As shown in FIG. 2, the second O-ring 8 is compressed in the optical axis direction X between the lens L2 and the lens L3 housed in the housing portion 208.

[0052] 11, a first inclination angle θ1 at which the tapered inner circumferential surface portion 4a located on the radial outside of the lens L6 is inclined with respect to the optical axis L, and a second inclination angle θ2 at which the tapered inner circumferential surface portion 4c located on the radial outside of the lens L4 is inclined with respect to the optical axis L are different. That is, the inclination of the inner circumferential surface portions 4a to 4d located on the radial outside of each lens and holder 28 can be appropriately set according to the outer diameter of each lens or holder 28. Note that, on the inner circumferential surface of the second barrel 4, the inner circumferential surface portion 4a located between the object side step 201 and the positioning step 203 is inclined overall toward the outer periphery toward the object side X1.

[0053] Next, the second lens barrel 4 has an annular outer peripheral surface side positioning surface 223 at the end portion of the object side X1 of the outer peripheral surface. The outer peripheral surface side positioning surface 223 is located radially outside the storage portion 208. The outer peripheral surface side positioning surface 223 faces radially outward. The second lens barrel 4 also has an outer peripheral surface image side step 224 at the image side X2 portion of the outer peripheral surface. The outer peripheral surface image side step 224 has an annular surface 225 facing the image side X2 and an outer peripheral surface portion 226 extending from the outer peripheral end of the annular surface 225 to the object side X1. Furthermore, the second lens barrel 4 has an outer peripheral surface intermediate step 227 between the end portion of the object side X1 on the outer peripheral surface (the outer peripheral surface side positioning surface 223) and the outer peripheral surface image side step 224. The outer peripheral surface intermediate step portion 227 has an annular surface 228 facing the image side X2 and an outer peripheral surface portion 229 extending from the inner peripheral end of the annular surface 228 toward the image side X2.

[0054] (Weld line position) Fig. 12 is a diagram showing the relationship between the position of the weld line formed on the second barrel and the position of the rib that positions the lens. The diagram on the left side of Fig. 12 is a diagram of the inside of the second barrel 4 viewed from the object side X1 along the optical axis L, the diagram in the center of Fig. 12 is a cross-sectional view of the surface along the optical axis L of the second barrel 4, and the diagram on the right side of Fig. 12 is a diagram of the second barrel 4 viewed from the image side X2 along the optical axis L.

[0055] 12, the positions of weld lines (see LW12-41) formed by joining together resins injected into the mold 300 (see also FIG. 14) of the second barrel 4 are located at positions that are off the center of at least each rib in the circumferential direction of the second barrel 4. Specifically, this is as follows.

[0056] Although details will be described later, in this embodiment, resin injected from multiple (e.g., four) pin gates IPG1 to IPG4 (see also FIG. 14) join together to form weld lines in the second barrel 4. Pin gate marks APG1 to APG4 are formed in the second barrel 4 in correspondence with the positions of the pin gates IPG1 to IPG4. Lines passing through the optical axis L and each of the pin gate marks APG1 to APG4 are designated LG1 to LG4.

[0057] Resin is injected from each of pin gates IPG1 to IPG4 into mold 300 and the weld lines formed by joining together are formed at position W1 on the outer peripheral surface side of second barrel 4 and position W2 on the inner surface side. The weld line position W1 portion rises outward from the outer peripheral surface of second barrel 4, and the weld line position W2 portion rises inward from the inner surface of second barrel 4. In this embodiment, the weld line formed at position W2 on the inner side is of concern, so only the weld line formed at position W2 on the inner side is of interest.

[0058] For example, a first weld line is formed by injecting resin from each of pin gate IPG1 and pin gate IPG2 into the mold 300 and joining the resins. When the inside of the second barrel 4 is viewed from the object side X1 along the optical axis L, a line passing through the optical axis L and each position of the first weld line is defined as line LW12. When the inside of the second barrel 4 is viewed from the object side X1 along the optical axis L, a line passing through the optical axis L and each position of the second weld line is defined as line LW23. When the inside of the second barrel 4 is viewed from the object side X1 along the optical axis L, a resin is injected into the mold 300 from each of pin gate IPG3 and pin gate IPG4 and joining the resins, a third weld line is formed. When the inside of the second barrel 4 is viewed from the object side X1 along the optical axis L, a line passing through the optical axis L and each position of the third weld line is defined as line LW34. Resin is injected into mold 300 from each of pin gate IPG4 and pin gate IPG1, and the resin flows together to form a fourth weld line. When the inside of second barrel 4 is viewed along optical axis L from object side X1, a line passing through optical axis L and each position of the fourth weld line is designated as line LW41.

[0059] The ribs 220A to 210B are arranged side by side along the optical axis L on the inner surface of the second barrel 4. A line LR1 passing through the optical axis L and the circumferential center R1c of each of the ribs 220A to 210B coincides and overlaps when the inside of the second barrel 4 is viewed along the optical axis L from the object side X1.

[0060] The lines LW12 and LR1 do not coincide when the inside of the second barrel 4 is viewed from the object side X1 along the optical axis L. Furthermore, a line passing through the optical axis L and each point within the region PR in which the ribs 220A to 210B are arranged does not overlap with the line LW12.

[0061] A line LR2 passing through the optical axis L and the center R2c of the rib 217 in the circumferential direction does not overlap with the line LW12.

[0062] In addition, the lines passing through the ribs 220A to 210B and the rib 217 arranged at other positions and the optical axis L do not overlap with the lines LW23, LW34, and LW41, as described above. The ribs 220A to 210B position the lenses L3, L4, and L6 in the radial direction, and the rib 217 positions the lens L6 in the axial direction.

[0063] The ribs 220A-210B are an example of a "first portion" of the technology of the present disclosure. The rib 217 is an example of a "second portion" of the technology of the present disclosure. The lenses L3, L4, and L6 are an example of a "first held lens" of the technology of the present disclosure, and the lens L6 is an example of a "second held lens".

[0064] Conventionally, the position of the weld line that rises from the surroundings is located at the circumferential center of the ribs 220A-210B or rib 217. Therefore, the position of the lens positioned by the ribs 220A-210B or rib 217 is shifted from the original position. This deteriorates the optical performance of the lens unit. Specifically, it deteriorates the coaxial accuracy of the lenses L3, L4, and L6 positioned by the ribs 220A-210B. In addition, the position of the lens L6 positioned by the rib 217 in the optical axis direction is shifted, and the imaging performance is deteriorated.

[0065] However, in this embodiment, the position of the weld line is at least at a position off the center of each of the ribs 220A to 210B, 217 in the circumferential direction of the second barrel 4. Therefore, it is possible to suppress deterioration of the coaxial accuracy of the lenses L3, L4, and L6 positioned by the ribs 220A to 210B, and also to suppress deviation of the position of the lens L6 in the optical axis direction positioned by the rib 217, thereby improving the positioning accuracy of the lenses compared to the conventional technology. Therefore, in this embodiment, it is possible to suppress deterioration of the optical performance of the lens unit. In other words, in this embodiment, the influence of the weld line generated by the resin flow does not overlap with the lens fitting portion or the lens seat surface, so that the lens is accurately assembled in the second barrel and stable optical performance can be ensured.

[0066] Moreover, in this embodiment, the influence of gas burns caused by the flow of resin on the circumferential center of the ribs 220A to 210B or the rib 217 can be suppressed.

[0067] FIG. 13 is a diagram of the second barrel 4 as viewed from the image side X2 along a direction shifted from the optical axis L, and shows the positions of the pin gate marks APG1 to APG4 formed on the second barrel 4. FIG.

[0068] 13, pin gate marks APG1 to APG4 are formed in second barrel 4 at positions corresponding to pin gates IPG1 to IPG4 (see also FIG. 14) formed by injecting resin into mold 300. Pin gate marks APG1 to APG4 are formed in the circumferential centers of ribs 220A to 210B at positions that do not overlap in the optical axis direction. In other words, lines LG1 to LG4 passing through optical axis L and pin gate marks APG1 to APG4 do not coincide with or overlap line LR1 when the interior of second barrel 4 is viewed along optical axis L from object side X1.

[0069] Residual stress is likely to remain near the pin gate. However, in this embodiment, as described above, the pin gate marks APG1 to APG4 are formed at positions that do not overlap in the optical axis direction at the circumferential centers of the ribs 220A to 210B, for which it is necessary to ensure the circularity. That is, the ribs 220A to 210B, 217 and the pin gate marks APG are disposed at positions that do not overlap in the optical axis direction. This makes it possible to further ensure the circularity.

[0070] (lens barrel manufacturing equipment) FIG. 14 is a block diagram of the lens barrel manufacturing apparatus 350.

[0071] As described above, the second barrel 4 is manufactured by injecting resin into the mold 300 of the second barrel 4. At a position of the mold 300 corresponding to the position of the image side X2 of the second barrel 4, a plurality of (for example, four) pin gates IPG1 to IPG4 having holes of the same size into which the resin is injected are provided concentrically about the optical axis L and at equal intervals in the circumferential direction. The pin gates IPG1 to IPG4 are provided so as to be symmetrical in the circumferential direction. In this embodiment, the holes of the pin gates IPG1 to IPG4 have the same size, and the flow rate per unit time of the resin injected into each of the pin gates IPG1 to IPG4 is the same. Therefore, the resin injected from each of the pin gates IPG1 to IPG4 advances at the same speed into the mold 300 and merges with the resin from the other pin gates. Therefore, the position of the weld line is a position in the mold 300 at the same distance from the adjacent pin gates IPG1 to IPG4. For example, the position of the weld line between the resin injected from pin gate IPG1 and the resin injected from pin gate IPG2 is at a position within mold 300 that is the same distance from each of pin gate IPG1 and pin gate IPG2.

[0072] The pin gates IPG1 to IPG4 are an example of an "entrance" of the technology of the present disclosure.

[0073] In this embodiment, the positions and sizes of the pin gates IPG1 to IPG4 are determined so that the weld lines are positioned at positions that are off the center of at least each of the ribs 220A to 210B, 217 in the circumferential direction of the second barrel 4. Therefore, when resin is injected into each of the pin gates IPG1 to IPG4 so that the flow rate per unit time is the same, the positions of the pin gates IPG1 to IPG4 and the weld lines are positioned at positions that are off the center of at least each of the ribs 220A to 210B, 217 in the circumferential direction of the second barrel 4.

[0074] The lens barrel manufacturing apparatus 350 includes a resin supply pump 306 that supplies resin, and valves 304N1-304N4 that are provided in piping 308N1-308N4 between the pin gates IPG1-IPG4 and the resin supply pump 306 for controlling the flow rate per unit time of the resin supplied from the resin supply pump 306.

[0075] The lens barrel manufacturing apparatus 350 includes a control device 302 that controls the apertures of the valves 304N1-304N4 so as to adjust the amount of resin per unit time injected into the pin gates IPG1-IPG4. The control device 302 controls the apertures of the valves 304N1-304N4 so as to position the weld lines at positions that are off the circumferential center of the ribs 220A-210B, 217 by adjusting the amount of resin per unit time injected into the pin gates IPG1-IPG4. The control device 302 is configured by a computer, and specifically includes a CPU, a ROM, a RAM, and input / output ports, which are not shown. The ROM stores a lens barrel manufacturing processing program (see also FIG. 15).

[0076] (Telescope barrel manufacturing processing program, telescope barrel manufacturing method and processing) 15 is a flowchart showing a lens barrel manufacturing processing program. The CPU executes the lens barrel manufacturing processing program to perform a method and processing for manufacturing the lens barrel.

[0077] In step 312, the opening degree of each of the valves 304N1 to 304N4 is acquired. The opening degree of each of the valves 304N1 to 304N4 is stored in a ROM or storage device (not shown) of the control device 302. In step 312, the opening degree is acquired from the ROM or storage device.

[0078] In this embodiment, the opening degree of each of the valves 304N1 to 304N4 is the same predetermined angle. When the opening degree of each of the valves 304N1 to 304N4 is the same predetermined angle, resin can be injected into each of the pin gates IPG1 to IPG4 so that the flow rate per unit time is the same, and therefore the position of the weld line can be positioned at least at a position off the center of each of the ribs 220A to 210B, 217 in the circumferential direction of the second barrel 4.

[0079] In step 314, the opening degree of each of the valves 304N1 to 304N4 is adjusted. Each of the valves 304N1 to 304N4 is controlled so that the opening degree of each of the valves 304N1 to 304N4 becomes the above opening degree read in step 312 from the ROM or storage device.

[0080] In step 316, the resin supply pump 306 is controlled so that the resin is injected into the mold 300 through the pin gates IPG1 to IPG4.

[0081] In step 318, it is determined whether the injection has ended by determining whether the time for the resin to be injected into the mold 300 has elapsed.

[0082] The resin supply pump 306 is controlled so that resin is injected into the mold 300 until it is determined that the time for injecting the resin into the mold 300 has elapsed (step 316).

[0083] When it is determined that the time for injecting the resin into the mold 300 has elapsed, it is determined that the injection is to be ended, and in step 320, the resin supply pump 306 is controlled so that the injection of the resin is ended.

[0084] By the above process, the weld lines are positioned at positions that are off the center of at least each of the ribs 220A to 210B and 217 in the circumferential direction of the second barrel 4.

[0085] Therefore, as described above, the lens positioning accuracy can be improved compared to the prior art.

[0086] (Modification) In the embodiment described above, multiple (for example, four) pin gates IPG1 to IPG4 into which resin is injected are provided at a position on mold 300 corresponding to the position of image side X2 of second barrel 4. The technology of the present disclosure is not limited to this, and two to eight pin gates other than four may be provided at the position on mold 300 corresponding to the position of image side X2 of second barrel 4, or one or more pin gates may be provided at a position on mold 300 corresponding to the side surface of second barrel 4.

[0087] In the above-mentioned embodiment, the flow rate per unit time of the resin injected into each of the pin gates IPG1 to IPG4 is the same, but the technology of the present disclosure is not limited to this. For example, the flow rate per unit time of the resin injected into the pin gates IPG1 and IPG2 is changed so that the line LW12 approaches the line LG2 side, specifically, the flow rate per unit time of the resin injected into the pin gate IPG1 is made slower than the flow rate per unit time of the resin injected into the pin gate IPG2. However, even if the flow rate per unit time of the resin injected into each of the pin gates IPG1 to IPG4 is changed in this way, the flow rate per unit time of the resin injected into each of the pin gates IPG1 to IPG4 is changed so that the position of the weld line is at least at a position that is off the center of each of the ribs 220A to 210B and 217 in the circumferential direction of the second barrel 4. Specifically, the opening degree of each of the valves 304N1 to 304N4 is adjusted.

[0088] The lens barrel manufacturing apparatus 350 of the embodiment described above includes one resin supply pump 306 and a plurality of (for example, four) valves 304N1 to 304N4. The technology of the present disclosure is not limited to this. A resin supply pump may be provided for each of the plurality of valves, and the flow rate of the resin injected into the mold 300 through each of the pipes 308N1 to 308N4 may be adjusted.

[0089] The lens barrel 2 of the embodiment described above includes a first lens barrel 3 and a second lens barrel 4 held on the inner periphery side of the first lens barrel 3, and the second lens barrel 4 is an example of the "lens barrel" of the technology of the present disclosure. The technology of the present disclosure is not limited to this. For example, the mold may be a mold that manufactures the first lens barrel 3 and the second lens barrel 4 as a single unit. Specifically, the lens barrel 2 manufactured by the mold includes the first lens barrel 3 and the second lens barrel 4. Ribs 220A-210B, 217 are provided on the inner surface of the second lens barrel 4. Pin gates IPG1-IPG4 are provided in the mold corresponding to the first lens barrel 3, and pin gate marks APG1-APG4 are formed on the first lens barrel 3. The mold is configured so that resin is injected from the pin gates IPG1-IPG4 into the first lens barrel 3 portion when molding the lens barrel 2, and the resin injected into the first lens barrel 3 portion flows into the second lens barrel 4 portion. Therefore, when molding the lens barrel 2, resin is first injected from the pin gates IPG1-IPG4 into the portion of the first lens barrel 3, and the resin injected into the portion of the first lens barrel 3 then flows into the portion of the second lens barrel 4. Therefore, in this modified example, the flow of resin can be sufficiently calmed by the time it reaches the portions of the ribs 220A-210B, 217, and deformation caused by variations in the strength of the resin flow and turbulence in the resin flow can be suppressed, thereby improving the circularity.

[0090] Although the shape of the first lens barrel 3 in the embodiment described above is cylindrical, the technology of the present disclosure is not limited to this, and the shape of the first lens barrel 3 may be an elliptical cylinder or a prismatic column. Furthermore, first lens barrel 3 may be provided integrally with the outer frame of the camera on which lens unit 1 is mounted.

[0091] In the above-described embodiment, the fitting protrusions 210A, the ribs 210B, and the guide protrusions 220 are provided at eight positions in the circumferential direction at equal angular intervals. However, the fitting protrusions 210A, the ribs 210B, and the guide protrusions 220 do not have to be provided at equal angular intervals, and the number of positions where they are provided is not limited to eight, and may be other numbers, such as six or seven. [Explanation of symbols]

[0092] 4. Second telescope IPG1~IPG4 Pin gate 220A~210B, 217 Rib APG1~APG4 Pin gate marks

Claims

1. A lens barrel for holding a lens therein, A portion for positioning the lens is provided, A lens barrel in which a weld line formed by the joining of resin injected into a mold for the lens barrel is located at a position that is off the circumferential center of the lens barrel at least in the portion to be positioned.

2. the lens barrel holds a plurality of lenses therein, including a first held lens and a second held lens; The portion for positioning the lens is A first portion for radially positioning the first held lens; a second portion for axially positioning the second held lens; The lens barrel according to claim 1 , further comprising at least one of the following:

3. The lens barrel according to claim 1 or 2, wherein a gate mark is formed in a position of a mold for the lens barrel corresponding to a position where the resin was injected.

4. The lens barrel according to claim 3 , wherein the gate mark is formed at a position that does not overlap with a center of the positioning portion in a circumferential direction of the lens barrel in an optical axis direction.

5. A mold for the lens barrel according to claim 1 or 2, an inlet for injecting the resin; The position of the inlet for injecting the resin is determined so that the position of a weld line formed by the joining of the injected resin is located at a position off the center in the circumferential direction of the portion for positioning the lens. Mold.

6. A mold for the lens barrel according to claim 1 or 2, a plurality of inlets for injecting the resin; The sizes of the plurality of inlets are determined so that a weld line formed by the joining of the injected resin is located at a position that is off the center in the circumferential direction of the portion that positions the lens. Mold.

7. A method for manufacturing the lens barrel according to claim 1 or 2, comprising the steps of: a mold for the lens barrel, the mold having a plurality of inlets for injecting the resin; Injecting the resin into the plurality of inlets so that a weld line formed by the joining of the resin injected into the mold for the lens barrel is located at a position that is off the center in the circumferential direction of the portion to be positioned. A method for manufacturing a lens barrel.

8. The method according to claim 7, further comprising adjusting the amount of the resin injected into the multiple inlets per unit time to position the weld line at a position that is off-center in the circumferential direction of the portion to be positioned.

9. A lens barrel including a first lens barrel and a second lens barrel that is held on an inner peripheral side of the first lens barrel and that holds a lens therein, a portion for positioning the lens is provided on an inner surface of the second lens barrel; the mold is configured so that the lens barrel is manufactured by injecting a resin into a portion of the mold for manufacturing the lens barrel that corresponds to the first lens barrel and then into a portion of the mold that corresponds to the second lens barrel, A lens barrel in which a weld line formed by the joining of resins injected into the mold is located at a position that is off the circumferential center of the lens barrel at least in the portion to be positioned.

Images