Lens barrel and image pickup apparatus

Abstract

To suppress deterioration in quality of a captured image.SOLUTION: A lens barrel includes a first frame and a second frame each holding an optical component, a guide member configured to guide the first frame and the second frame linearly along an optical axis, a cam barrel configured to move the first frame and the second frame along the optical axis by relative rotation with the guide member, a first engagement portion provided on the first frame, and a second engagement portion provided on the second frame and configured to engage with the first engagement portion. To prevent an interval between a first frame and a second frame in a direction along an optical axis from becoming a predetermined amount or more.SELECTED DRAWING: Figure 8

Description

[Technical Field]

[0001] The present invention relates to a lens barrel and an imaging device. [Background technology]

[0002] There is a lens barrel in which the spacing between frames that each hold a lens and are movable along the optical axis is maintained constant by using the biasing force of a spring (see, for example, Patent Document 1). If the lens barrel is subjected to an impact, for example, and the spacing between the frames changes against the biasing force of the spring, there is a risk that the quality of the captured image will deteriorate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-086608 Summary of the Invention

[0004] According to a first aspect, the lens barrel includes a first frame and a second frame that each hold an optical component, a guide member that guides the first frame and the second frame in a straight line along the optical axis, a cam barrel that moves the first frame and the second frame along the optical axis by rotating relative to the guide member, a first engagement portion provided on the first frame, and a second engagement portion provided on the second frame that engages with the first engagement portion, and the engagement between the first engagement portion and the second engagement portion prevents the distance between the first frame and the second frame in the direction along the optical axis from exceeding a predetermined amount.

[0005] According to a second aspect, an imaging device includes the above-described lens barrel.

[0006] The configuration of the present embodiment described below may be modified as appropriate, and at least a part of it may be replaced with other components. Furthermore, components that are not particularly limited in their placement may be placed in any position that can achieve their function, not limited to the placement disclosed in the embodiment. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a cross-sectional view of the camera. [Figure 2] FIG. 2 is an exploded perspective view of a portion of the lens barrel. [Figure 3] FIG. 3 is a perspective view of the fixed barrel and the cam barrel. [Figure 4] FIG. 4 is a perspective view of the cam barrel. [Figure 5] FIG. 5 is a perspective view of the fixed barrel holding the unit. [Figure 6] FIG. 6 is a perspective view of the fixed barrel. [Figure 7] FIG. 7 is an exploded perspective view of the unit. [Figure 8] FIG. 8 shows the unit in the wide position. [Figure 9] FIG. 9 shows the unit in the tele position. [Figure 10] FIG. 10 shows the unit in the tele position. [Figure 11] 11A and 11B are perspective views of the rod. [Figure 12] FIG. 12 is a cross-sectional view showing the rod and its surroundings. [Figure 13] FIG. 13A is an explanatory diagram of the first change amount, and FIG. 13B is an explanatory diagram of the second change amount. DETAILED DESCRIPTION OF THE INVENTION

[0008] [Camera configuration] Figure 1 is a cross-sectional view of camera A. Figure 1 shows an optical axis OA. In this specification, the subject side will be referred to as the front side, the image plane side will be referred to as the rear side, the front end of a member or configuration will be referred to as the front edge, the rear end of a member or configuration will be referred to as the rear edge, and the direction around the optical axis OA will be referred to as the circumferential direction.

[0009] Camera A includes a camera body B and a lens barrel C. The lens barrel C has a lens mount LM at its rear end, which engages with the body mount of the camera body B, allowing it to be detachably attached to the camera body B. Camera body B includes an image sensor IS and a control unit (not shown) inside. The image sensor IS is composed of a photoelectric conversion element such as a CCD (Charge Coupled Device), and converts the subject image formed by the imaging optical system (the lens barrel C attached to the camera body B) into an electrical signal. The control unit includes a CPU (Central Processing Unit), and provides overall control of the overall operation of camera A related to photography, including focusing drive in the camera body B and lens barrel C, and blur correction of captured images caused by camera shake, etc. Camera A is an example of an imaging device.

[0010] The lens barrel C holds lens groups L1 to L7 in this order from the subject side to the image plane side. The lens barrel C is a so-called zoom lens with an adjustable focal length. Each of the lens groups L1 to L7 may consist of a single lens or multiple lenses. The lens barrel C includes holding frames 10, 20, 30, 100, 110, 120, and 130, a rotating ring 40, a rod 50, a fixed barrel 60, a cam barrel 70, a zoom operation ring 80, external barrels 90 and 140, a focus operation ring 150, and a lens mount LM. The holding frames 10, 20, 30, 100, 110, 120, and 130 hold lens groups L1, L2, L3, L4, L5, L6, and L7, respectively. The lens groups L1, L4, L5, and L7 are fixed in a direction along the optical axis OA.

[0011] The holding frame 10 is fixed to the tip of the fixed barrel 60. The holding frame 100 is held at the rear end of the outer barrel 90. The holding frames 20 and 30, the rotating ring 40, and the rod 50 constitute a unit U. The unit U is located within the fixed barrel 60 and the cam barrel 70. The unit U moves along the optical axis OA as the cam barrel 70 rotates relative to the fixed barrel 60. The fixed barrel 60 is an example of a guide member. The fixed barrel 60 is disposed between the unit U and the cam barrel 70. The rotating ring 40, which will be described in detail later, is held rotatably around the optical axis OA relative to the holding frame 20. The rod 50, which will be described in detail later, is held by the holding frame 30. The holding frame 30 is an example of a first frame. The holding frame 20 and the rotating ring 40 are an example of a second frame. The unit U moves together within a predetermined range along the optical axis OA. The front end of the movable range of the unit U corresponds to the wide position (wide-angle end). The rear end of the movable range of unit U corresponds to the tele position (telephoto end). In Figure 1, unit U at the wide position is shown above the optical axis OA, and unit U at the tele position is shown below the optical axis OA.

[0012] The cam barrel 70 is disposed on the outside of the fixed barrel 60. The exterior barrel 90 is disposed on the outside of the cam barrel 70. The zoom operation ring 80 is disposed on the outside of the exterior barrel 90. The rear end of the exterior barrel 90 is fixed to the front end of the holding frame 130. The exterior barrel 140 and the focus operation ring 150 are disposed on the outside of the holding frame 130. The focus operation ring 150 is disposed forward of the exterior barrel 140. The holding frame 110 is fixed to the rear end of the exterior barrel 90 so that it is positioned within the holding frame 130. A tripod ring TR can be attached to the outside of the exterior barrel 140. A tripod mount TM can be attached to the tripod ring TR.

[0013] The holding frame 130 holds a guide bar 132 extending along the optical axis OA. The guide bar 132 supports the holding frame 120 so that it can move along the optical axis OA. The lens group L6 held by the holding frame 120 is a focus lens that moves during focusing. In FIG. 1, the holding frame 120 and lens group L6 are indicated by solid lines when focused on an object at infinity, and by dashed double-dashed lines when focused on an object at a close distance. The holding frame 120 moves along the optical axis OA by an actuator (not shown). When the focus operation ring 150 is rotated during manual focusing, the actuator is driven to move the holding frame 120 along the optical axis. The lens groups L4, L5, and L7 are located closer to the image than the lens groups L2 and L3 and are examples of image-side lenses that are fixed in a direction along the optical axis OA. The lens group L6 is disposed between the holding frame 30 and the lens group L7, and is an example of a movable lens that is movable along the optical axis OA.

[0014] [Outline of lens barrel configuration] FIG. 2 is an exploded perspective view of a portion of the lens barrel C. The retaining frame 20 has three pairs of slider portions 27 and cam followers 28 spaced equiangularly around the circumference. As will be described in detail later, the cam followers 28 protrude radially outward from the slider portions 27. The slider portions 27 and cam followers 28 are an example of a second protrusion. The retaining frame 30 has three pairs of slider portions 37 and cam followers 38 spaced equiangularly around the circumference. The slider portions 37 and cam followers 38 are an example of a first protrusion. Three springs S1 bias the retaining frames 20 and 30 toward each other, generally parallel to the optical axis direction. The rotating ring 40 has three cam followers 48 spaced equiangularly around the circumference. The cam followers 48 are an example of a third protrusion. Three rods 50 are held by the retaining frame 30. The front ends of the rods 50 engage with the rotating ring 40. The rotating ring 40 and the rod 50 will be described in detail later. Although the springs S1 are arranged at equal angular intervals in the circumferential direction in Fig. 2, there may be only one spring S1 or the arrangement may not be at equal angular intervals.

[0015] The fixed barrel 60 has three pairs of rectilinear grooves 65 and 66 formed at equal angular intervals in the circumferential direction. The rectilinear grooves 65 and 66 extend linearly along the optical axis OA and are parallel to each other. The slider portions 27 and 37 engage with the rectilinear grooves 65 and 66, respectively. This allows the holding frames 20 and 30 to be guided linearly along the optical axis OA. The rectilinear groove 65 is an example of a second rectilinear guide portion. The rectilinear groove 66 is an example of a first rectilinear guide portion. The cam barrel 70 is rotatable relative to the fixed barrel 60. The cam barrel 70 has three cam protrusions 78 formed at equal angular intervals in the circumferential direction. The cam protrusions 78 slide against the cam followers 28 and 38. When the cam barrel 70 rotates relative to the fixed barrel 60, the cam protrusions 78 and the rectilinear grooves 65 and 66 move the holding frames 20 and 30 along the optical axis OA. The cam protrusion 78 is an example of a first cam portion.

[0016] The exterior barrel 90 includes an outer barrel portion 91 and an inner barrel portion 93. The inner barrel portion 93 is formed further forward than the outer barrel portion 91. The inner barrel portion 93 has a smaller outer diameter than the outer barrel portion 91. The zoom operation ring 80 is rotatably held on the radially outer side of the inner barrel portion 93. The cam barrel 70 is fixed to the inner surface of the zoom operation ring 80. Therefore, when the user rotates the zoom operation ring 80 relative to the exterior barrel 90, the cam barrel 70 rotates together with the zoom operation ring 80 relative to the fixed barrel 60. This causes the unit U to move along the optical axis OA.

[0017] [Configuration of fixed barrel and cam barrel] FIG. 3 is a perspective view of the fixed barrel 60 and the cam barrel 70. FIG. 4 is a perspective view of the cam barrel 70. FIG. 5 is a perspective view of the fixed barrel 60 holding the unit U. FIG. 6 is a perspective view of the fixed barrel 60. As shown in FIGS. 3 and 4, the cam barrel 70 has a cylindrical portion 72. The cylindrical portion 72 has an outer peripheral surface 721 and an inner peripheral surface 722. The cam protrusion 78 protrudes radially inward from the inner peripheral surface 722. The outer peripheral surface 721 has a recess 78x recessed radially inward at a position corresponding to the cam protrusion 78. The cam protrusion 78 extends obliquely with respect to the optical axis OA. The cam protrusion 78 has a front end 781 and a rear end 782. The cam protrusion 78 includes side surfaces 783 and 784. The width along the optical axis OA between the side surfaces 783 and 784 gradually decreases from the front end 781 to the rear end 782. That is, the inclination angle of the side surface 783 relative to the optical axis OA is smaller than the inclination angle of the side surface 784 relative to the optical axis OA. As shown in Figure 3, the movement of the cam barrel 70 in the direction of the optical axis OA is restricted by the front end portion 62 and the positioning pin PS.

[0018] As shown in FIGS. 5 and 6 , the fixed barrel 60 includes a front end 62 and a cylindrical portion 64. The cylindrical portion 64 is located rearward of the front end 62. The outer diameter of the front end 62 is larger than the outer diameter of the cylindrical portion 64. The cylindrical portion 64 has the above-mentioned linear grooves 65 and 66 formed at approximately equal intervals in the circumferential direction. The linear grooves 65 and 66 have front ends 651 and 661 and rear ends 652 and 662, respectively. The cylindrical portion 64 has an outer peripheral surface 641 and an inner peripheral surface 642. As shown in FIGS. 3 and 5 , a positioning pin PS is attached to the outer peripheral surface 641. Three cam grooves 67 are formed in the inner peripheral surface 642 at equal angular intervals in the circumferential direction. The cam groove 67 is formed between two pairs of linear grooves 65 and 66 adjacent to each other in the circumferential direction. The cam groove 67 is inclined with respect to the optical axis OA. The inclination angle of cam groove portion 67 relative to the optical axis OA varies depending on the position in the direction of the optical axis OA. The average inclination angle of cam groove portion 67 relative to the optical axis OA is smaller than the average inclination angle of cam protrusion 78 relative to the optical axis OA. Cam groove portion 67 includes a front end 671 and a rear end 672. Cam groove portion 67 will be described in detail later.

[0019] The slider portions 27 and 37 engage with the linear grooves 65 and 66, respectively. The cam followers 28 and 38 protrude radially outward from the linear grooves 65 and 66, respectively. The cam followers 28 and 38 abut against the side surfaces 783 and 784 of the cam protrusion 78, respectively, due to the biasing force of the spring S1 described above. The side surfaces 783 and 784 are indicated by dotted lines in FIG. 5. In the state shown in FIG. 5, the unit U is positioned at the wide position. When the cam barrel 70 rotates in the circumferential direction CD1 shown in FIG. 3 relative to the fixed barrel 60 with the unit U in the wide position, the cam followers 28 and 38 move toward the rear end 782 along the cam protrusion 78, and the slider portions 27 and 37 move toward the rear ends 652 and 662 along the linear grooves 65 and 66, respectively. In this manner, the unit U moves from the wide position to the telephoto position. 3 relative to the fixed barrel 60, the cam followers 28 and 38 move toward the front end 781 along the cam protrusion 78, and the slider portions 27 and 37 move toward the front ends 651 and 661 along the rectilinear grooves 65 and 66, respectively. In this way, the unit U moves from the telephoto position to the wide-angle position.

[0020] [Unit configuration] FIG. 7 is an exploded perspective view of the unit U. The holding frame 20 has, from the front side to the rear side, a holding ring portion 22, a flange portion 24, and a support ring portion 26. The holding ring portion 22 holds the lens group L2. The flange portion 24 protrudes radially outward beyond the holding ring portion 22 and the support ring portion 26. Each of the three slider portions 27 extends rearward from the outer peripheral edge of the flange portion 24. The three slider portions 27 are provided at equal angular intervals in the circumferential direction. Each slider portion 27 has a predetermined radial thickness and is rectangular in shape with its longitudinal direction along the optical axis OA. The cam follower 28 protrudes radially outward from the outer surface of the slider portion 27. The cam follower 28 is annular.

[0021] The support ring portion 26 is formed with claw portions 264. The claw portions 264 extend rearward from the support ring portion 26, with their rear ends protruding radially outward. Three claw portions 264 are provided at equal angular intervals in the circumferential direction. The slider portion 27 and the cam follower 28 are located radially outward of the claw portions 264. Three claw portions 241 are formed at equal angular intervals in the circumferential direction in the flange portion 24. The claw portions 241 engage the front ends of the springs S1. Three notches 245 are formed at equal angular intervals in the circumferential direction in the flange portion 24. The slider portion 27, the claw portions 241, the notches 245, and the claw portions 264 are located at mutually different circumferential positions. The slider portion 27, the claw portions 241, and the notches 245 are arranged in order along the circumferential direction. By arranging the slider portion 27, the claw portion 241, and the notch portion 245 close to each other in the circumferential direction, the cam follower 28 and the cam follower 38 can be brought close to each other and one cam protrusion 78 can be sandwiched between them.

[0022] The holding frame 30 has a holding ring portion 32 and a flange portion 34. The flange portion 34 is provided near the rear end of the holding ring portion 32. The flange portion 34 protrudes radially outward beyond the holding ring portion 32. The lens group L3 is held inside the holding ring portion 32. The flange portion 34 has three claws 341 arranged at equal angular intervals in the circumferential direction. The claws 341 engage the rear ends of the springs S1. The flange portion 34 has three relief holes 344 arranged at equal angular intervals in the circumferential direction. The flange portion 34 has three storage portions 35 arranged at equal angular intervals in the circumferential direction. The storage portions 35 extend in the front-rear direction from the flange portion 34. The storage portions 35 have storage holes 351 extending in the front-rear direction. As will be described in detail later, the rod 50, spring S5, washer W, and screw SC are housed in the storage holes 351, and the rear ends of the storage holes 351 are closed by a cover CV.

[0023] The slider portion 37 is provided on the outer surface of the accommodation portion 35. The slider portion 37 has a predetermined radial thickness and is rectangular with its longitudinal direction along the optical axis OA. The cam follower 38 protrudes radially outward from the outer surface of the slider portion 37. The cam follower 38 is annular. The radial distance of the slider portion 37 from the optical axis OA is approximately the same as the radial distance of the slider portion 27 from the optical axis OA. The radial distance of the cam follower 38 from the optical axis OA is approximately the same as the radial distance of the cam follower 28 from the optical axis OA. The accommodation portion 35, the claw portion 341, and the relief hole 344 are located at different circumferential positions. The circumferential positions of the claw portions 241 and 341 correspond to each other. The circumferential positions of the relief hole 344 and the claw portion 264 correspond to each other.

[0024] The rotary ring 40 has an annular portion 42. The inner diameter of the annular portion 42 is larger than the outer diameter of the support ring portion 26. The cam followers 48 protrude radially outward from the outer peripheral surface of the annular portion 42. The cam followers 48 are pin-shaped. Three cam protrusions 45 are provided on the outer peripheral surface of the annular portion 42 at equal angular intervals in the circumferential direction. The cam protrusions 45 protrude from the outer peripheral surface of the annular portion 42. The cam protrusions 45 extend along the optical axis OA. More specifically, the cam protrusions 45 extend linearly and inclined relative to the optical axis OA. The cam protrusions 45 are an example of a second engagement portion. The cam protrusions 45 are inelastic. The three cam protrusions 45 have the same inclination angle relative to the optical axis OA. The cam protrusions 45 have a front end 451 and a rear end 452. The circumferential positions of the cam protrusions 45 and the cam followers 48 are different from each other. Three notches 425 are formed in part of the rear edge of the annular portion 42 at equal angular intervals in the circumferential direction.

[0025] [Unit in wide position] FIG. 8 is a diagram showing the unit U in the wide position. The annular portion 42 of the rotating ring 40 is located radially outward from the support ring portion 26 of the holding frame 20 and radially inward from the slider portion 27. This restricts misalignment of the rotating ring 40 relative to the holding frame 20 in a direction perpendicular to the optical axis OA. The rotating ring 40 is located between the flange portion 24 and the rear end of the claw portion 264, and the rotating ring 40 does not move forward from the flange portion 24, nor does the rotating ring 40 move rearward from the claw portion 264. This restricts misalignment of the rotating ring 40 relative to the holding frame 20 in the direction along the optical axis OA. With this restriction on misalignment, the rotating ring 40 is held rotatably in the circumferential direction relative to the holding frame 20.

[0026] The outer diameter of the retaining ring portion 32 of the retaining frame 30 is smaller than the inner diameter of the support ring portion 26. Therefore, the retaining ring portion 32 is located radially inward of the support ring portion 26. The spring S1 is engaged by the claw portions 241 and 341 and is located parallel to the optical axis between the circumferentially adjacent cam followers 28 and 38, and is located radially outward of the annular portion 42 of the rotating ring 40. Because the cam protrusion 78 is sandwiched between the cam follower 28 and the cam follower 38, the spring S1 is located on the inner circumferential side of the cam protrusion 78. Furthermore, as will be described in detail later, the front end of the rod 50 housed in the housing portion 35 protrudes forward from the housing portion 35 and engages with the cam protrusion 45. The rod 50 is inelastic. In the wide position, the rod 50 engages near the rear end 452 of the cam protrusion 45. The rod 50 extends along the optical axis OA. The rod 50 is an example of a first engagement portion. The cam follower 48 of the rotary ring 40 protrudes radially outward beyond the outer diameters of the flanges 24 and 34 and engages with the cam groove portion 67 of the fixed barrel 60.

[0027] [Unit in tele position] 9 and 10 are diagrams showing unit U at the tele position. At the tele position, the distance between holding frame 20 and holding frame 30 in the direction along the optical axis OA is closer than at the wide position. This is because, as described above, the distance in the direction along the optical axis OA between side surfaces 783 and 784 of cam protrusion 78, with which cam followers 28 and 38 respectively abut, gradually decreases from the wide position to the tele position.

[0028] Furthermore, as the unit U moves from the wide position to the tele position, the cam follower 48 of the rotating ring 40 moves from the front end 671 to the rear end 672 of the cam groove portion 67. This causes the rotating ring 40 to rotate in the circumferential direction CD1 relative to the holding frames 20 and 30, and the rod 50 held by the holding frame 30 moves relatively from the rear end 452 to the front end 451 of the cam protrusion portion 45. This causes the rod 50 to approach the holding frame 20, and the holding frame 30 holding the rod 50 also approaches the holding frame 20.

[0029] Similarly, as the unit U moves from the telephoto position to the wide-angle position, the cam follower 48 of the rotating ring 40 moves from the rear end 672 to the front end 671 of the cam groove portion 67. This causes the rotating ring 40 to rotate in the circumferential direction CD2 relative to the holding frames 20 and 30, and the rod 50 held by the holding frame 30 moves relatively from the front end 451 to the rear end 452 of the cam protrusion 45. This causes the rod 50 to move away from the holding frame 20, and the holding frame 30 holding the rod 50 also moves away from the holding frame 20. In this way, the rotation of the rotating ring 40 relative to the holding frame 20 changes the engagement position of the cam protrusion 45 with the rod 50.

[0030] At the telephoto position, the holding frame 20 and the rotating ring 40 approach the holding frame 30. At the telephoto position, as shown in FIG. 9, the notch 245 prevents interference between the flange portion 24 and the rod 50. Similarly, the notch 425 prevents interference between the rod 50 and the annular portion 42. Furthermore, as shown in FIG. 10, the claw portion 264 is inserted into the relief hole 344, preventing interference between the claw portion 264 and the flange portion 34. The cam follower 48 moves in the circumferential direction between a pair of cam followers 28 and 38 that are adjacent to each other in the circumferential direction and another pair of cam followers 28 and 38 that are adjacent to each other in the circumferential direction. This prevents interference between the cam follower 48 and the cam follower 28 or 38.

[0031] [Rod configuration] 11A and 11B are perspective views of the rod 50. The rod 50 has a cylindrical portion 52, a plate portion 54, and protruding portions 56 and 58. The cylindrical portion 52 has a generally cylindrical shape extending along the optical axis OA. The cylindrical portion 52 has an outer peripheral surface 521. The axis of the cylindrical portion 52 is generally parallel to the optical axis OA. A screw hole 522 extending along the optical axis OA is formed in the cylindrical portion 52. The plate portion 54 is formed forward of the cylindrical portion 52. The plate portion 54 has a plate shape extending along the optical axis OA. The plate portion 54 has an outer surface 541 and an inner surface 542. When viewed from the direction of the axis of the cylindrical portion 52, the outer surface 541 is located radially outward of the outer peripheral surface 521 of the cylindrical portion 52. A step portion 543 is defined by the outer surface 541 and the outer peripheral surface 521. When viewed from the direction of the axis of the cylindrical portion 52, the inner surface 542 is located more inward than the outer peripheral surface 521 of the cylindrical portion 52. Protrusions 56 and 58 are formed on the inner surface 542. Protrusion 56 is located more forward than protrusion 58. Protrusion 58 is formed on the cylindrical portion 52 side. Protrusions 56 and 58 face each other at a predetermined distance in the direction along the optical axis OA. Protrusion 56 has a curved surface 561 facing protrusion 58. Protrusion 58 has a curved surface 581 facing protrusion 56.

[0032] FIG. 12 is a cross-sectional view of the rod 50 and its surroundings. The cross section in FIG. 12 is a plane including the optical axis OA. FIG. 12 shows the unit U in the wide position. The rear side of the accommodation hole 351 of the accommodation section 35 is closed by a cover CV. The accommodation hole 351 has, from the rear side to the front side, a large-diameter surface 352, a medium-diameter surface 353, and a small-diameter surface 354. The inner diameter of the medium-diameter surface 353 is smaller than the inner diameter of the large-diameter surface 352. The inner diameter of the small-diameter surface 354 is smaller than the inner diameter of the medium-diameter surface 353. A washer W is fixed to the rear end of the cylindrical portion 52 by a screw SC threaded into the screw hole 522. The outer diameter of the washer W is smaller than the inner diameter of the large-diameter surface 352 but larger than the inner diameter of the medium-diameter surface 353. The spring S5 is coil-shaped. The inner diameter of the spring S5 is larger than the outer diameter of the cylindrical portion 52. The inner diameter of the small diameter surface 354 is approximately the same as the outer diameter of the cylindrical portion 52 of the rod 50. The small diameter surface 354 is defined by a protrusion 355 that protrudes radially inward from the medium diameter surface 353. The protrusion 355 is located on the front side of the accommodating hole 351. With the cylindrical portion 52 inserted into the spring S5, the spring S5 is disposed between the protrusion 355 and the washer W. This causes the rod 50 to be biased rearward by the spring S5. Here, the step portion 543 abuts against the protrusion 355. Therefore, the rod 50 is biased rearward by the spring S5 so that the state in which the step portion 543 abuts against the protrusion 355 is maintained.

[0033] In this way, the cam protrusion 45 is maintained sandwiched between the protrusions 56 and 58 of the rod 50. That is, the rotary ring 40 and the rod 50 are maintained in an engaged state, and the unit U moves along the optical axis OA between the wide position and the tele position. In this way, the engagement between the cam protrusion 45 of the rotary ring 40 and the rod 50 prevents the distance between the holding frame 20 and the holding frame 30 in the direction along the optical axis OA from exceeding a predetermined amount.

[0034] Here, for example, if the rotating ring 40 and the rod 50 are not provided and an impact is applied to the lens barrel C, the cam follower 28 of the holding frame 20 may move away from the side surface 783 of the cam protrusion 78 against the biasing force of the spring S1, or the cam follower 38 of the holding frame 30 may move away from the side surface 784 of the cam protrusion 78, which may momentarily increase the distance between the holding frame 20 and the holding frame 30 beyond a predetermined distance. Particularly at the telephoto position, the holding frame 20 and the holding frame 30 may come closer to each other, shortening the length of the spring S1 and reducing the biasing force of the spring S1, which is likely to cause the above-mentioned problems. As a result, the quality of the captured image may be reduced.

[0035] In this embodiment, even if an impact is applied to the lens barrel C, the engagement between the cam protrusion 45 of the rotating ring 40 and the rod 50 prevents the above-mentioned gap from exceeding a predetermined amount. This prevents a decrease in the quality of the captured image. As described above, the cam protrusion 45 of the rotating ring 40 and the rod 50 are not elastic members like a spring, but are inelastic. This effectively prevents the above-mentioned gap from exceeding a predetermined amount.

[0036] Furthermore, curved surface 561 of convex portion 56 and curved surface 581 of convex portion 58 come into contact with cam protrusion 45. As a result, curved surfaces 561 and 581 each come into line contact with cam protrusion 45. Therefore, sliding resistance between cam protrusion 45 and convex portions 56 and 58 is reduced.

[0037] The average inclination angle of cam groove portion 67 with respect to the optical axis OA is smaller than the average inclination angle of cam protrusion 78 with respect to the optical axis OA. In other words, the amount of rotation of rotating ring 40 about the optical axis OA relative to holding frame 20 from the wide-angle end to the telephoto end is smaller than the amount of rotation of cam barrel 70 about the optical axis OA relative to fixed barrel 60 from the wide-angle end to the telephoto end. For this reason, sliding resistance when cam follower 48 moves within cam groove portion 67 is suppressed.

[0038] [Change in spacing between holding frames 20 and 30] Next, we will explain the amount of change in the gap between the holding frame 20 and the holding frame 30 along the optical axis OA due to the cam protrusion 78 of the cam barrel 70 (hereinafter referred to as the first change amount), and the amount of change in the gap due to the rotary ring 40 and the rod 50 (hereinafter referred to as the second change amount). FIG. 13A is an explanatory diagram of the first change amount. FIG. 13A schematically shows the cam protrusion 78 of the cam barrel 70 developed in a plane. FIG. 13A shows the relative positions of the cam followers 28 and 38 with respect to the cam protrusion 78 at the wide position and the telephoto position. Distance Dc indicates the circumferential distance between the cam followers 28 and 38. Distance Dc is always constant due to the rectilinear grooves 65 and 66, regardless of the positions of the cam followers 28 and 38. Distance D1 indicates the distance from the cam follower 28 to the cam follower 38 along the optical axis OA at the wide position. At the wide position, the cam follower 38 is a distance D1 behind the cam follower 28. Distance D2 indicates the distance along the optical axis OA from one cam follower 28 to another cam follower 38 at the tele position. At the tele position, the cam follower 38 is a distance D2 ahead of the cam follower 28. Therefore, the first amount of change, which is the difference between the amount of movement of the cam follower 28 from the wide position to the tele position and the amount of movement of the cam follower 38 from the wide position to the tele position, is the distance (D1 + D2). The rotation angle Ra indicates the rotation angle of the cam barrel 70 required to move the holding frame 20 and the holding frame 30 from the wide position to the tele position.

[0039] FIG. 13B is an explanatory diagram of the second change amount. FIG. 13B is a schematic planar view of the cam protrusion 45 of the rotary ring 40. FIG. 13B shows the relative position of the rod 50 with respect to the cam protrusion 45 at the wide-angle and telephoto positions. The rotation angle Rb indicates the rotation angle of the rotary ring 40 as the unit U moves from the wide-angle position to the telephoto position. The rotation angle Rb corresponds to the circumferential angle of the cam groove 67 from the front end 671 to the rear end 672. The rotation angle Rb is smaller than the rotation angle Ra. However, the second change amount required for the rod 50 to move from the wide-angle position to the telephoto position is set to be approximately equal to the distance (D1 + D2), which is the same as the first change amount. That is, under the constraint that the rotation angle Rb is smaller than the rotation angle Ra, the inclination angle of the cam protrusion 45 with respect to the optical axis OA is set so that the first change amount and the second change amount are the same. This ensures that the above-mentioned amount of change in spacing (first amount of change) caused by the cam protrusion 78 is maintained, while the rotating ring 40 and the rod 50 prevent the spacing between the holding frames 20 and 30 from changing beyond the spacing determined by the cam protrusion 78.

[0040] As shown in FIG. 12 , the rod 50 is held in the housing portion 35 of the holding frame 30 so as to be movable within a predetermined range in the direction along the optical axis OA. Specifically, a gap is secured between the step portion 543 and the protrusion 355 in the direction along the optical axis OA, and a gap is secured between the step portion defined between the large-diameter surface 352 and the medium-diameter surface 353 and the washer W in the direction along the optical axis OA. This facilitates assembly when engaging the protrusions 56 and 58 of the rod 50 held in the holding frame 30 with the cam protrusion 45 of the rotating ring 40 held in the holding frame 20. In addition, the rod 50 is biased rearward relative to the holding frame 30 by the spring S5. This reduces rattling of the rod 50.

[0041] In the above embodiment, three pairs of slider portions 27 and 37, cam followers 28 and 38, housing portions 35, cam protrusion portions 45, cam followers 48, rods 50, springs S1, rectilinear grooves 65 and 66, cam groove portions 67, and cam protrusion portions 78 are provided, but the number is not limited to three. The respective numbers of slider portions 27 and 37, cam followers 28 and 38, rectilinear grooves 65 and 66, and cam protrusion portions 78 may be different from the respective numbers of housing portions 35, cam protrusion portions 45, cam followers 48, rods 50, and cam groove portions 67. The respective numbers of cam protrusion portions 45 and rods 50 may be different from the respective numbers of cam followers 48 and cam groove portions 67.

[0042] As an example of the first cam portion, cam protrusion 78 is recessed radially inward from inner circumferential surface 722, but the first cam portion is not limited to cam protrusion 78. The first cam portion may protrude radially outward from outer circumferential surface 721 and be recessed radially outward from inner circumferential surface 722, or may be a single hole provided in tubular portion 72. In this case, cam follower 28 may abut against one of the opposing inner surfaces of the first cam portion, and cam follower 38 may abut against the other of the inner surfaces. In this case, spring S1 may bias retaining frames 20 and 30 away from each other so that cam followers 28 and 38 abut against one and the other of the opposing inner surfaces of the first cam portion, respectively.

[0043] Although the fixed barrel 60 having the rectilinear grooves 65 and 66 has been described as an example of the guide member, the guide member is not limited to the fixed barrel 60. The guide member may be a guide bar that extends in a direction along the optical axis OA and engages with the holding frames 20 and 30.

[0044] By providing spring S1, the holding frame 20 and the holding frame 30 can be biased so that they directly attract each other, and the biasing force can be transmitted efficiently without reduction in the biasing force due to friction. On the other hand, spring S1 does not have to be provided. Even if spring S1 is not provided, the engagement between cam protrusion 45 and rod 50 can prevent the gap between holding frame 20 and holding frame 30 from exceeding a predetermined amount.

[0045] If the second and third groups were biased solely by spring S1, the distance between the holder frame 20 and the holder frame 30 would change from the wide-angle position to the telephoto position, causing a change in the load of spring S1 due to a change in the tension length, resulting in a difference in torque between the wide-angle position and the telephoto position. On the other hand, if spring S5 is provided, the biasing force can be distributed between springs S1 and S5, thereby suppressing the change in the load of spring S1. Spring S5 may bias rod 50 forward. Rod 50 may be integrally formed with holder frame 30. Holder frame 20 may hold rod 50, and holder frame 30 may hold rotating ring 40. Furthermore, to more efficiently transmit the biasing force of spring S5, protrusions 56 and 58 of rod 50 may be bearings. Similarly, cam follower 48 of rotating ring 40 may be a bearing.

[0046] Each of the holding frames 20 and 30 may hold an optical component other than a lens. The optical component may be, for example, a filter that adjusts the amount of light or limits wavelength.

[0047] Although seven lens groups L1 to L7 are provided, the number of lens groups can be changed. Lens groups L2 and L3, which are arranged in front of lens group L4 fixed to fixed barrel 60, are positioned on the optical axis by a cam mechanism consisting of cam protrusion 78 and cam followers 28 and 38. Lens groups L5 to L7, which are arranged behind lens group L4, are positioned on the optical axis by being fixed or by a motor and a mechanism for transmitting driving force from the motor. Therefore, there are three lens groups that move along the optical axis, and two of these lens groups can be moved by a single cam mechanism, allowing the zoom lens to change magnification with a simple structure without using multiple cam mechanisms.

[0048] In the above embodiment, the position of lens group L2 in the optical axis direction is determined by the contact position between the cam follower 28 and the cam protrusion 78. The position of lens group L3 in the optical axis direction is determined by the contact position between the cam follower 38 and the cam protrusion 78. Here, since the cam protrusion 78 is sandwiched between the cam followers 28 and 38, when an impact is received from the front, for example, the impact is in a direction that causes the lens group L2 to contact the cam protrusion 78, and the lens group L2 does not move rearward. However, if the lens group L3 receives an impact in a direction that causes the lens group L3 to move away from the cam protrusion 78, the lens group L3 may move rearward, which may degrade the optical performance of the zoom lens. However, in this embodiment, the engagement between the rod 50 and the cam protrusion 45 prevents the distance between the lens group L2 and the lens group L3 in the optical axis direction from exceeding a predetermined amount. In other words, even if the lens group L3 receives an impact force that moves rearward, the engagement between the rod 50 and the cam protrusion 45 prevents the lens group L3 from moving rearward. The distance between lens group L2 and lens group L3 changes depending on the focal length of the zoom lens, but the engagement position between cam protrusion 45 and rod 50 also changes depending on the focal length, so the above effect can be obtained over the entire magnification range of the zoom lens.

[0049] In the above embodiment, there is no need to use two corresponding cam grooves (or cam protrusions) to move the lens groups L2 and L3, and one cam protrusion 78 can do the job. Therefore, there is no need to provide six cam grooves (cam protrusions) on the inner peripheral surface of the cam barrel 70, and it is sufficient to provide only three cam protrusions 78. When providing three cam protrusions 78 on the inner peripheral surface of the cam barrel 70, by arranging the cam protrusions 78 within a range of 120 degrees around the optical axis, it is possible to avoid having two cam protrusions 78 lined up in the optical axis direction, which makes it easier to remove the inner part of the cam barrel 70 when molding it from plastic.

[0050] The above-described embodiment is a preferred example of implementation, but is not limited to this, and various modifications are possible within the scope of the gist, and any constituent elements may be combined. [Explanation of symbols]

[0051] OA optical axis A Camera B Camera Body C Lens barrel L1~L7 lens group U Unit S1, S5 springs 20, 30 slots 27, 37 Slider part 28, 38, 48 Cam Follower 40 Rotating Ring 45 Cam protrusion 50 rods 56, 58 Convex parts 60 Fixed tube 65, 66 Straight groove 67 Cam groove 70 Cam barrel 78 Cam protrusion

Claims

1. a first frame and a second frame each holding an optical component; a guide member that guides the first frame and the second frame linearly along the optical axis; a cam barrel that moves the first frame and the second frame along the optical axis by rotating relative to the guide member; a first engagement portion provided on the first frame; a second engaging portion provided on the second frame and engaging with the first engaging portion, The lens barrel, wherein engagement between the first engagement portion and the second engagement portion prevents the distance between the first frame and the second frame in the direction along the optical axis from becoming equal to or greater than a predetermined amount.

2. the cam barrel moves the first frame and the second frame along the optical axis while changing the distance between the first frame and the second frame in the direction along the optical axis, The lens barrel according to claim 1 , wherein the second frame includes a holding frame that holds the optical component, and a rotating ring that is provided with the second engagement portion and is rotatable around the optical axis relative to the holding frame.

3. 3. The lens barrel according to claim 2, wherein when the rotating ring rotates around the optical axis relative to the holding frame, an engagement position of the second engagement portion with respect to the first engagement portion changes, and a distance between the first frame and the second frame in a direction along the optical axis changes.

4. the second engagement portion has a shape extending along the optical axis of the rotary ring, The first engagement portion has a shape extending along the optical axis. The lens barrel according to claim 3 .

5. the cam barrel has a first cam portion for moving the first frame and the second frame along the optical axis, the first engagement portion is held by the first frame so as to be movable within a predetermined range in a direction along the optical axis, 5. The lens barrel according to claim 2, further comprising a first biasing member that biases the first engagement portion toward one side in a direction along the optical axis relative to the first frame so that the first frame and the second frame abut against the first cam portion.

6. the guide member has a second cam portion that rotates the rotary ring around the optical axis relative to the holding frame in response to movement of the rotary ring along the optical axis, the cam barrel rotates relative to the guide member around the optical axis, causing the first cam portion to move the first frame and the second frame from a wide-angle end to a telephoto end; 6. The lens barrel according to claim 5, wherein an amount of rotation of the rotary ring about the optical axis relative to the holding frame from the wide-angle end to the telephoto end is smaller than an amount of rotation of the cam barrel about the optical axis relative to the guide member from the wide-angle end to the telephoto end.

7. a second biasing member having one end attached to the first frame and the other end attached to the second frame; The lens barrel according to claim 5 , wherein the first frame and the second frame are biased toward the first cam portion by the second biasing member.

8. 8. The lens barrel according to claim 5, wherein the first cam portion is convex, concave, or hole-shaped and has first and second surfaces that abut against the first frame and the second frame, respectively, and that face each other in the direction along the optical axis.

9. the guide member has a first rectilinear groove and a second rectilinear groove extending in a direction along the optical axis, the first frame includes a first protrusion, the second frame includes a second protrusion, The lens barrel according to claim 5 , wherein the first protrusion and the second protrusion are engaged with the first rectilinear groove and the second rectilinear groove, respectively, and come into sliding contact with the first cam portion.

10. 10. The lens barrel according to claim 1, wherein the guide member is a fixed barrel that is disposed between the first frame, the second frame, and the cam barrel and is fixed in a circumferential direction around the optical axis.

11. the rotary ring includes a third protrusion, The lens barrel according to claim 6 , wherein the third protrusion engages with the second cam portion.

12. The lens barrel according to claim 1 , wherein the first frame is disposed closer to an image plane than the second frame.

13. an image-side lens disposed closer to the image plane than the first frame; The lens barrel according to claim 1 , wherein the image-side lens is fixed in a direction along an optical axis.

14. The lens barrel according to claim 13 , further comprising a movable lens disposed between the first frame and the image-side lens and movable along the optical axis.

15. The lens barrel according to claim 1 , wherein the first engagement portion and the second engagement portion are inelastic.

16. An imaging device comprising the lens barrel according to any one of claims 1 to 15.

Images