Lens barrel and imaging device

Abstract

This lens barrel comprises: a first frame that holds a lens; a drive unit that includes a drive shaft and drives the first frame in the optical axis direction; and a second frame that has at least two guide parts for guiding driving of the first frame in the optical axis direction. On a plane orthogonal to the optical axis, at least one of said at least two guide parts is disposed on a second straight line that is orthogonal to a first straight line passing through the axis of the drive shaft and the optical axis and that passes through the optical axis.

Description

Lens barrel and imaging device

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

[0002] 2. Description of the Related Art Optical devices such as lens barrels are equipped with a lens moving device that moves a lens group during zooming and focusing operations.

[0003] There is a demand for improved precision in controlling the position of the lens group.

[0004] International Publication No. 2018 / 105200

[0005] According to a first aspect, the lens barrel comprises a first frame that holds a lens, a drive unit that includes a drive shaft and drives the first frame in the optical axis direction, and a second frame that has at least two guide units that guide the drive of the first frame in the optical axis direction, and in a plane perpendicular to the optical axis, at least one of the at least two guide units is arranged on a second line that is perpendicular to a first line passing through the axis of the drive shaft and the optical axis and passes through the optical axis.

[0006] According to a second aspect, the lens barrel includes a first frame that holds a lens, a drive unit that includes a drive shaft and drives the first frame in the optical axis direction, a second frame that has at least two guide units that guide the drive of the first frame in the optical axis direction, an inner ring fixed to the first frame, and an outer ring that can rotate relative to the inner ring, and the outer peripheral surface of the outer ring abuts against the guide units.

[0007] According to a third aspect, the lens barrel is a lens barrel having a first frame and a second frame that move relative to each other in the optical axis direction, and is provided with at least two drip-proof members provided in a gap between the first frame and the second frame that connects the outside and inside of the lens barrel.

[0008] According to a fourth aspect, an imaging device includes the lens barrel described above.

[0009] The configurations of the embodiments described below may be modified as appropriate, and at least a portion of the configuration may be replaced with other components. Furthermore, components that are not particularly limited in terms of their placement may be placed in any position that can achieve their function, not limited to the placement disclosed in the embodiments.

[0010] FIGS. 1A and 1B are cross-sectional views showing the configuration of a camera equipped with a lens barrel according to an embodiment, with FIG. 1A showing an infinity state and FIG. 1B showing a close-up state. FIG. 2 is a perspective view of a first fixed barrel member. FIG. 3 is an exploded perspective view of an optical system block. FIG. 4A is an exploded perspective view of a moving block, and FIG. 4B is a perspective view of the moving block as viewed from the image plane side. FIG. 5 is an enlarged view of a portion C1 surrounded by a dotted line in FIG. 1A. FIG. 6 is a perspective view for explaining the configuration of a drive mechanism. FIG. 7 is a cross-sectional view for explaining the configuration of a drive mechanism. FIG. 8 is a diagram for explaining the arrangement of first to third guide grooves. FIG. 9A is a diagram schematically showing an example of the arrangement of first to third guide grooves according to a comparative example, and FIG. 9B is a diagram for explaining the reason for arranging the first guide groove and second guide groove on a second straight line. 10A is an enlarged view of a portion C2 surrounded by a dotted line in FIG. 1A, and FIG. 10B is a cross-sectional view showing a drip-proof structure according to a comparative example.

[0011] The lens barrel according to the embodiment will be described in detail below with reference to the drawings. Note that the scale of the shape, length, thickness, etc. of each part shown in the embodiment does not necessarily correspond to the actual product, and in each drawing, some elements may be omitted for ease of understanding. Also, in cross-sectional views, hatching of some elements may be omitted.

[0012] 1A and 1B are cross-sectional views showing the configuration of a camera 1 equipped with a lens barrel 2 according to one embodiment, with FIG. 1A showing the infinity state and FIG. 1B showing the close-up state.

[0013] 1A and 1B, the camera 1 includes a camera body 3 and a lens barrel 2. The lens barrel 2 has a lens mount LM at the rear (proximal end) thereof, and is detachably attached to the camera body 3 by engaging the lens mount LM with a body mount (not shown) of the camera body 3. In this embodiment, the lens barrel 2 is detachable from the camera body 3, but this is not limiting, and the lens barrel 2 and the camera body 3 may be integrated.

[0014] The camera body 3 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 2 attached to the camera body 3) into an electrical signal.

[0015] The control unit includes a CPU (Central Processing Unit) and the like, and controls the overall operation of the camera 1 relating to photography, including focusing drive of the camera body 3 and the attached lens barrel 2 .

[0016] The lens barrel 2 includes a fixed barrel 13, a focus ring 12, and an optical system block 100 that moves along the optical axis OA in response to operation of the focus ring 12 or user operation via the camera body 3. A first fixed barrel member 13a and a second fixed barrel member 13b are arranged within the fixed barrel 13. The optical system block 100 is an example of a first frame, and the first fixed barrel member 13a is an example of a second frame.

[0017] FIG. 2 is a perspective view of the first fixed barrel member 13a. As shown in FIG. 2, a first guide groove 11a, a second guide groove 11b, and a third guide groove 11c are formed on the inner periphery of the first fixed barrel member 13a to guide the optical system block unit 100 in the optical axis OA direction. Each of the first guide groove 11a to the third guide groove 11c is a linear groove extending in the optical axis OA direction, and its bottom surface is stepped, with the bottom surface on the object side being located closer to the outer diameter than the bottom surface on the image plane side (see FIGS. 1A and 1B). The arrangement of the first guide groove 11a to the third guide groove 11c will be described in detail below. The first guide groove 11a to the third guide groove 11c are an example of a guide unit.

[0018] Fig. 3 is an exploded perspective view of the optical system block unit 100. As shown in Fig. 1A, Fig. 1B, and Fig. 3, the optical system block unit 100 includes a lens holding frame F1, a lens group L1, an aperture mechanism 40, a moving block unit 200, a lens holding frame F2, and a lens group L2.

[0019] Lens groups L1 and L2 are sequentially arranged along a common optical axis OA, with lens group L1 held in a lens holding frame F1 and lens group L2 held in a lens holding frame F2. Lens groups L1 and L2 are focus lens groups. As described above, the optical system block 100, including lens groups L1 and L2, moves along the optical axis OA in response to operation of the focus ring 12 or user operation via the camera body 3, etc. In other words, the lens barrel 2 according to this embodiment employs a focusing system that drives the entire optical system as a focus group. This allows the overall length of the lens barrel 2 along the optical axis OA to be shorter than, for example, when an inner focus system is employed. In other words, the lens barrel 2 can be made more compact.

[0020] Each of the lens groups L1 and L2 may be composed of a single lens or multiple lenses. Although the lens barrel is described as being composed of two lens groups, it may be composed of one lens group or three or more lens groups.

[0021] The diaphragm mechanism 40 is disposed between the lens groups L1 and L2.

[0022] Fig. 4(A) is an exploded perspective view of the moving block unit 200, and Fig. 4(B) is a perspective view of the moving block unit 200 seen from the image plane side. Fig. 5 is an enlarged view of a portion C1 surrounded by a dotted line in Fig. 1(A). As shown in Figs. 4(A) and 4(B), the moving block unit 200 includes a connecting portion 10, a moving portion 20, and a biasing portion holding portion 30.

[0023] The biasing portion holder 30 holds the first biasing member 81 and the second biasing member 82, and is fixed to the connecting portion 10 by a screw 73. As shown in FIG. 5 , a part of the moving portion 20 is disposed between the connecting portion 10 and the biasing portion holder 30.

[0024] As shown in Fig. 5 , in this embodiment, the first biasing member 81 is a coil spring. As shown in Fig. 5 , the first biasing member 81 is housed in a hole 20b provided in the moving portion 20, with one end contacting a bottom portion 20c of the hole 20b and the other end contacting the biasing portion holder 30. As a result, as shown by arrow A2 in Fig. 5 , the moving portion 20 is biased toward the connecting portion 10, thereby suppressing backlash in the optical axis direction between the moving portion 20 and the connecting portion 10. When the moving portion 20 moves in the optical axis direction, the connecting portion 10 also moves in the optical axis direction. Note that the first biasing member 81 is not limited to a coil spring as long as it can bias the moving portion 20 toward the connecting portion 10, and may be a leaf spring or the like.

[0025] 4B and 5, the second biasing member 82 is a coil spring, one end of which contacts the moving part 20 and the other end of which contacts the biasing part holder 30. As a result, the moving part 20 is biased toward the lead screw 302, which will be described later, as shown by arrow A1 in Fig. 5. Note that the second biasing member 82 is not limited to a coil spring, and may be a leaf spring or the like, as long as it can bias the moving part 20 toward the lead screw 302.

[0026] 3, a lens holding frame F1 and a lens holding frame F2 are connected to the connecting portion 10. Specifically, the lens holding frame F1 is fixed to the connecting portion 10 by a screw 71, and the lens holding frame F2 is fixed to the connecting portion 10 by a screw 72.

[0027] As described above, the connecting portion 10 is connected to the moving portion 20 by the first biasing member 81 and the biasing portion holding portion 30. As a result, when the moving portion 20 moves in the optical axis OA direction, the lens holding frames F1 and F2 move in the optical axis OA direction.

[0028] As shown in Figures 4(A) and 4(B), the connecting portion 10 includes a cylindrical portion 10a, and a first groove engaging portion 101a, a second groove engaging portion 101b, and a third groove engaging portion 101c that protrude radially from the cylindrical portion 10a.

[0029] The first groove engagement portion 101a has a front protrusion 112a and a rear protrusion 113a that protrude radially and are spaced apart in the direction of the optical axis OA, as well as a front bearing 102a and a rear bearing 103a. The outer periphery of the front protrusion 112a is fitted with the inner ring of the front bearing 102a, and the outer periphery of the rear protrusion 113a is fitted with the inner ring of the rear bearing 103a. As a result, the front bearing 102a and the rear bearing 103a are spaced apart in the direction of the optical axis OA.

[0030] The front bearing 102a and the rear bearing 103a engage with the first guide groove 11a. The front bearing 102a and the rear bearing 103a move along the first guide groove 11a while rotating. As a result, the friction generated when the first groove engagement portion 101a moves within the first guide groove 11a is rolling friction. Therefore, compared to, for example, when the front protrusion 112a and the rear protrusion 113a engage with the first guide groove 11a without a bearing, the sliding resistance when the first groove engagement portion 101a moves within the first guide groove 11a is reduced, and the load on the drive unit (the stepping motor 301 described later) that moves the moving unit 20 in the optical axis OA direction can be reduced.

[0031] Similar to the first groove engagement portion 101a, the second groove engagement portion 101b has a front protrusion 112b (not shown) and a rear protrusion 113b (not shown) that protrude radially and are spaced apart in the direction of the optical axis OA, as well as a front bearing 102b and a rear bearing 103b. The outer periphery of the front protrusion 112b is fitted with the inner ring of the front bearing 102b, and the outer periphery of the rear protrusion 113b is fitted with the inner ring of the rear bearing 103b. As a result, the front bearing 102b and the rear bearing 103b are spaced apart in the direction of the optical axis OA.

[0032] The front bearing 102b and the rear bearing 103b engage with the second guide groove 11b. As a result, the friction generated when the second groove engagement portion 101b moves within the second guide groove 11b is rolling friction. Therefore, the load applied to the stepping motor 301 when the second groove engagement portion 101b moves within the second guide groove 11b can be reduced compared to, for example, a case in which the front protrusion 112b and the rear protrusion 113b engage with the second guide groove 11b without the use of bearings.

[0033] Similar to the first groove engagement portion 101a, the third groove engagement portion 101c has a front protrusion 112c and a rear protrusion 113c (see FIGS. 1A and 1B) that protrude radially and are spaced apart in the direction of the optical axis OA, as well as a front bearing 102c and a rear bearing 103c. The outer periphery of the front protrusion 112c is fitted with the inner ring of the front bearing 102c, and the outer periphery of the rear protrusion 113c is fitted with the inner ring of the rear bearing 103c. As a result, the front bearing 102c and the rear bearing 103c are spaced apart in the direction of the optical axis OA.

[0034] The front bearing 102c and the rear bearing 103c engage with the third guide groove 11c. As a result, the friction generated when the third groove engagement portion 101c moves within the third guide groove 11c is rolling friction. Therefore, compared to, for example, a case in which the front protrusion 112c and the rear protrusion 113c engage with the third guide groove 11c without the use of bearings, the load applied to the stepping motor 301 when the third groove engagement portion 101c moves within the third guide groove 11c can be reduced.

[0035] In this embodiment, the rear bearing 103a is located radially inward of the front bearing 102a, the rear bearing 103b is located radially inward of the front bearing 102b, and the rear bearing 103c is located radially inward of the front bearing 102c. This ensures sufficient space around the outer periphery of the rear bearings 103a-103c to accommodate other components such as flexible substrates. This configuration also allows for longer distances between the front bearing 102a and the rear bearing 103a, between the front bearing 102b and the rear bearing 103b, and between the front bearing 102c and the rear bearing 103c. This prevents the central axes of the lens groups L1 and L2 from tilting relative to the optical axis OA, thereby improving the optical performance of the lens barrel 2. The distance between the front bearing 102a and the rear bearing 103a, the distance between the front bearing 102b and the rear bearing 103b, and the distance between the front bearing 102c and the rear bearing 103c may be the same or different.

[0036] As described above, the focusing method of the lens barrel 2 according to this embodiment is a full extension method, so the optical system block 100 protrudes from the lens barrel 2. In this case, if the lens barrel 2 is dropped, an impact will be directly applied to the focus lens group. By supporting the optical system block 100 with the first guide groove 11a to the third guide groove 11c and the first groove engaging portions 101a to the third groove engaging portions 101c according to this embodiment, it is possible to increase the strength against impact compared to when the optical system block 100 is supported by, for example, a single guide bar.

[0037] 4A, the moving section 20 is formed with a hole 20a that houses a lead screw engaging section 303 provided in a drive mechanism 300 that drives the optical system block section 100, and a hole 20b that houses the above-mentioned first biasing member 81. Here, the drive mechanism 300 that drives the optical system block section 100 will be described.

[0038] Fig. 6 is a perspective view for explaining the configuration of the drive mechanism 300, and is a perspective view of the drive mechanism 300 and the optical system block unit 100 as seen from the image plane side. Fig. 7 is a cross-sectional view for explaining the configuration of the drive mechanism 300. Fig. 8 is a diagram for explaining the arrangement of the first to third guide grooves, and is a plan view of the optical system block unit 100 and the first fixed barrel member 13a as seen from the object side.

[0039] As shown in FIG. 6 , the drive mechanism 300 includes a stepping motor 301 , a lead screw 302 , and a lead screw engaging portion 303 .

[0040] In this embodiment, a stepping motor 301 is used as a drive source for the lead screw 302. When a user operates the focus operation ring 12 or performs an operation via the camera body 3, an internal lens control unit (not shown) rotates the lead screw 302 in accordance with the amount of operation, thereby moving the optical system block unit 100 in the direction of the optical axis OA.

[0041] In this embodiment, the position of the optical system block unit 100 is controlled by open-loop control of the stepping motor 301. In other words, the position of the optical system block unit 100 is not detected and fed back to the lens internal control unit. This makes it possible to omit a position detection unit (feedback sensor, etc.) for feedback control of the position of the optical system block unit 100, leading to a reduction in size and cost of the lens barrel 2. The position of the optical system block unit 100 is represented by the number of steps (number of rotations) of the stepping motor 301, and therefore position data represented by the number of steps is transmitted to the camera body 3 or the lens internal control unit as necessary.

[0042] As shown in FIG. 8 , in this embodiment, the output shaft 301a of the stepping motor 301 and the lead screw 302 are connected via gears 305a to 305c. Specifically, as shown in FIG. 8 , the output shaft 301a is disposed on the object side of the stepping motor 301. A gear 305a is attached to the object side end of the output shaft 301a of the stepping motor 301, a gear 305b is attached to the object side end of the lead screw 302, and a gear 305c that engages with the gears 305a and 305b is disposed between the gears 305a and 305b. The combined length of the stepping motor 301 and the output shaft 301a in the optical axis direction is approximately equal to the length of the lead screw 302 in the optical axis direction. Therefore, the stepping motor 301, its output shaft 301a, and the lead screw 302 are disposed parallel to each other and closer to the image side than the gears 305a to 305c. As a result, rotational force is transmitted from the object side end of output shaft 301a of stepping motor 301 via gear 305c to the object side end of lead screw 302. With this configuration, output shaft 301a of stepping motor 301 and lead screw 302 are arranged in a folded manner, so the overall length of lens barrel 2 in the optical axis OA direction can be shortened compared to when the output shaft and lead screw are directly connected. The combined length of stepping motor 301 and output shaft 301a in the optical axis direction and the length of lead screw 302 in the optical axis direction can be changed as appropriate.

[0043] As shown in FIG. 7 , the lead screw 302 is rotatably supported by a lead screw support mechanism 304 and the first fixed barrel member 13a. In this embodiment, the lead screw support mechanism 304 rotatably supports one end of the lead screw 302 via a bearing 304a, and the first fixed barrel member 13a rotatably supports the other end of the lead screw 302 via a bearing 304b. By supporting both ends of the lead screw 302 with bearings in this manner, the load on the stepping motor 301 when rotating the lead screw 302 can be reduced. In this embodiment, the position of the optical system block unit 100 is controlled by open-loop control of the stepping motor 301. Therefore, if an excessive load is applied to the stepping motor 301, it may be impossible to obtain the desired movement amount of the optical system block unit 100 for a given drive amount of the stepping motor 301. Therefore, in this embodiment, the load on the stepping motor 301 is reduced, thereby improving the position control accuracy of the optical system block unit 100.

[0044] 7, the lead screw engagement portion 303 includes an annular member 303a and a bearing 303b. The outer periphery of the annular member 303a is fitted into the inner ring of the bearing 303b. The outer periphery of the bearing 303b is fitted into the inner periphery of a hole 20a provided in the moving portion 20.

[0045] A groove 313 is formed on the inner periphery of the annular member 303a so as to come into contact with the thread groove of the lead screw 302. The groove 313 is a circumferential groove formed around the entire inner periphery of the annular member 303a.

[0046] 7, the annular member 303a is urged by the second urging member 82 toward the lead screw 302 in a direction perpendicular to the axis AX1 of the lead screw 302. As a result, the groove 313 of the annular member 303a is pressed against the thread groove of the lead screw 302, thereby suppressing play between the annular member 303a and the lead screw 302. Furthermore, the lead screw engaging portion 303 is housed in a hole 20a formed in the moving portion 20, so that the moving portion 20 and the lead screw engaging portion 303 are connected to each other.

[0047] Because the annular member 303a is rotatably supported, when the lead screw 302 rotates, the annular member 303a is pushed by the flank surface of the thread groove of the lead screw 302 and moves in the axial direction of the lead screw 302 while rotating. As a result, the moving unit 20 engaged with the lead screw engaging portion 303 also moves in the axial direction of the lead screw 302. As the moving unit 20 moves, the optical system block unit 100 moves in the direction of the optical axis OA while being guided by the first guide groove 11a to the third guide groove 11c provided in the first fixed barrel member 13a.

[0048] Because the annular member 303a moves in the direction of the axis AX1 of the lead screw 302 while rotating, the friction generated between the annular member 303a and the lead screw 302 is rolling friction. This reduces the load on the stepping motor 301 when moving the optical system block unit 100 in the axial direction of the lead screw 302, thereby improving the position control accuracy of the optical system block unit 100. Note that the structure disclosed in Japanese Patent Application No. 2021-156263 may be applied as the structure of the lead screw engagement unit 303.

[0049] Next, the arrangement of the first guide groove 11a to the third guide groove 11c of the first fixed barrel member 13a will be described. In this embodiment, as shown in Fig. 8, the first guide groove 11a and the second guide groove 11b are arranged on a second straight line LN2 that is perpendicular to a first straight line LN1 that passes through the axis AX1 of the lead screw 302 and the optical axis OA and that passes through the optical axis OA. Furthermore, the third guide groove 11c is arranged on the first straight line LN1.

[0050] The reason for arranging the first guide groove 11a to the third guide groove 11c as described above will now be explained. FIG. 9A is a diagram schematically illustrating an example of the arrangement of the first guide groove 901a, the second guide groove 901b, and the third guide groove 901c according to a comparative example. In this comparative example, the first guide groove 901a to the third guide groove 901c are arranged at 120-degree intervals. In this case, if the backlash gap between the first guide groove 901a to the third guide groove 901c and, for example, the front bearings 102a to 102c is a, the backlash gap b in a direction parallel to the first line LN1 passing through the axis AX1 of the lead screw 302 and the optical axis OA is, for example, b = a / cos θ in the first guide groove 901a. This is larger than the backlash gap a in the design. Therefore, the optical system block 100 has a larger backlash in the pitch direction in FIG. 9A, which affects the drive accuracy accordingly. Therefore, in this embodiment, the first guide groove 11a and the second guide groove 11b are positioned at the position where θ = 0° and b = a, i.e., on the second straight line LN2 perpendicular to the first straight line LN1. In this way, tilting of the optical system block unit 100 is suppressed, improving the positional accuracy of the optical system block unit 100. Furthermore, the third guide groove 11c located on the first straight line LN1 contributes to backlash in the yaw direction in FIG. 9A , but does not affect drive performance near the center of the optical axis due to the positional relationship of the fulcrum. Furthermore, even in drive performance in the peripheral area away from the optical axis, because the orientation of the third guide groove 11c is vertical in FIG. 9A , minimal backlash is required, and backlash in the yaw direction is also small, so drive accuracy is not significantly affected.

[0051] FIG. 9B is a diagram illustrating another reason for arranging the first guide groove 11a and the second guide groove 11b on the second straight line LN2. Similar to FIG. 9A, the first guide groove 901a to the third guide groove 901c are arranged at 120-degree intervals. Now, as shown in the right diagram of FIG. 9B, assume that the entire lens barrel 2 is tilted around the position (rotation center RC1) where the first guide groove 901a or the second guide groove 901b is provided. In this case, the position of the rotation center RC1 is shifted by an amount indicated by D from the center position of the lens group. This shift amount D is a deviation in the optical axis direction due to lens tilt, and results in an accuracy error. By arranging the first guide groove 11a and the second guide groove 11b on the second straight line LN2, accuracy errors resulting from the position of the rotation center of the lens barrel 2 can be reduced. 9A, but does not affect the drive performance near the center of the optical axis due to the positional relationship of the fulcrum. Also, even in the drive performance of the peripheral area away from the optical axis, because the orientation of the third guide groove 11c is vertical in FIG. 9A, play is minimal and play in the yaw direction is also small, so it does not significantly affect accuracy errors.

[0052] In this way, in this embodiment, the load on the stepping motor 301 is reduced, and by arranging the first guide groove 11a to the third guide groove 11c as described above, the position control accuracy of the optical system block section 100 is improved.

[0053] <Drip-proof Structure> In the lens barrel 2 according to this embodiment, the optical system block 100 may move in the direction of the optical axis OA, causing the lens retaining frame F1 to protrude from the lens barrel 2, as shown in FIG. 1B . In this case, it is undesirable for water droplets that have adhered to the lens retaining frame F1 due to rainfall or the like to enter the interior of the lens barrel 2 through the gap between the second fixed barrel member 13b and the lens retaining frame F1. Therefore, the lens barrel 2 is provided with a drip-proof structure that prevents water droplets that have adhered to the lens retaining frame F1 from entering the interior of the lens barrel 2.

[0054] FIG. 10A is a diagram for explaining a drip-proof structure 90 according to this embodiment, and is an enlarged view of a portion C2 surrounded by a dotted line in FIG. 1A.

[0055] As shown in FIG. 10A , the lens barrel 2 according to this embodiment includes a lens holding frame F1 that moves in the optical axis direction and a second fixed barrel member 13b that is disposed radially outward of the lens holding frame F1. As the lens holding frame F1 moves in the optical axis direction, the relative positional relationship between the lens holding frame F1 and the second fixed barrel member 13b in the optical axis direction changes. A space S is formed between the lens holding frame F1 and the second fixed barrel member 13b as a gap that connects the exterior and interior of the lens barrel 2. A drip-proof structure 90 is provided in the space S. The drip-proof structure 90 includes a first drip-proof member 91 and a second drip-proof member 92 that is formed from a different material than the first drip-proof member 91. The lens holding frame F1 is an example of a first frame, and the second fixed barrel member 13b is an example of a second frame. In this embodiment, the lens holding frame F1 is movable in the optical axis OA direction relative to the second fixed barrel member 13b, and the lens holding frame F1 and the second fixed barrel member 13b do not rotate relative to each other in the circumferential direction.

[0056] The first drip-proof member 91 and the second drip-proof member 92 are arranged side by side in the optical axis direction, and the first drip-proof member 91 is arranged closer to the object side than the second drip-proof member 92 .

[0057] In this embodiment, the first drip-proof member 91 is a water-absorbent elastic member (a member with cushioning properties) and is arranged to surround the outer periphery of the lens holding frame F1. Examples of materials for the first drip-proof member 91 include a nonwoven fabric structure, synthetic leather, raised fabric, or flocked fabric. In this embodiment, the first drip-proof member 91 is a nonwoven fabric structure with a water-repellent agent applied to the surface facing the lens holding frame F1. The thickness of the first drip-proof member 91 is approximately constant in the optical axis direction, and the cross section of the first drip-proof member 91 is rectangular.

[0058] A gap is provided between the first drip-proof member 91 and the lens holding frame F1. In other words, the first drip-proof member 91 and the lens holding frame F1 are not in contact with each other. This reduces sliding resistance compared to when the first drip-proof member 91 is in contact with the lens holding frame F1, and reduces the drive load when the optical system block unit 100 moves in the optical axis OA direction. This stabilizes the posture of the optical system block unit 100, improving the optical performance of the lens barrel 2 and reducing the load on the stepping motor 301. This improves the position control accuracy of the optical system block unit 100.

[0059] The second drip-proof member 92 is an annular elastic member that is coated with a material that improves slipperiness. The second drip-proof member 92 is, for example, a rubber sheet that is coated with a material that improves slipperiness. The second drip-proof member 92 has a substantially constant thickness and is disposed so as to have an inverted L-shaped cross section. One end of the inner circumferential surface of the second drip-proof member 92 is fixed in contact with the lens holding frame F1, and the other end is fixed to the object side of the lead screw support mechanism 304 that is fixed to the second fixed barrel member 13b.

[0060] With the drip-proof structure 90, when the optical system block 100 is moved, for example, from a close-up position to an infinity position, the water-repellent properties of the first drip-proof member 91 prevent water droplets adhering to the lens holding frame F1 from penetrating into the interior of the lens barrel 2. Even if water droplets penetrate into the interior of the lens barrel 2 (space S in FIG. 10A ), the second drip-proof member 92 prevents the water droplets from penetrating further into the lens barrel 2 (the image plane side of the lead screw support mechanism 304 and the second fixed barrel member 13b). Water droplets that penetrate into space S are absorbed by the water-absorbent first drip-proof member 91 and evaporate from the first drip-proof member 91 over time. Even if there are water droplets that are not absorbed by the first drip-proof member 91, the provision of the second drip-proof member 92 reliably prevents them from penetrating into the interior of the lens barrel 2.

[0061] As a result, the drip-proof structure 90 can achieve drip-proof performance comparable to that of a drip-proof structure in which the nonwoven fabric structure 991 is crushed and brought into contact with the lens holder frame F1, as in the comparative example shown in FIG. 10B . If the nonwoven fabric structure 991 is crushed and brought into contact with the lens holder frame F1, friction occurs between the nonwoven fabric structure 991 and the lens holder frame F1 when the optical system block unit 100 moves in the optical axis OA direction, resulting in drive resistance and a load on the stepping motor 301. When a load is applied to the stepping motor 301, even if the stepping motor 301 is driven a predetermined amount, the drive resistance may cause the amount of movement of the optical system block unit 100 to not accurately correspond to the predetermined amount. In this embodiment, the first drip-proof member 91 does not contact the lens holder frame F1, thereby reducing the load on the stepping motor 301. This improves the position control accuracy of the optical system block unit 100.

[0062] Note that crushing the nonwoven fabric structure 991 means that the cross-sectional height of the nonwoven fabric structure 991 when assembled to the lens barrel is smaller than the cross-sectional height of the nonwoven fabric structure 991 when not assembled to the lens barrel.

[0063] As described in detail above, according to this embodiment, the lens barrel 2 comprises an optical system block portion 100 that holds lens groups L1 and L2, a drive mechanism 300 that includes a lead screw 302 and drives the optical system block portion 100 in the direction of the optical axis OA, and a first fixed cylinder member 13a that has first guide grooves 11a to third guide grooves 11c that guide the drive of the optical system block portion 100 in the direction of the optical axis OA, and in a plane perpendicular to the optical axis OA, the first guide groove 11a and the second guide groove 11b of the first guide groove 11a to third guide groove 11c are perpendicular to a first straight line LN1 that passes through the axis AX1 of the lead screw 302 and the optical axis OA, and are arranged on a second straight line LN2 that passes through the optical axis OA.

[0064] As a result, as explained with reference to Figures 9(A) and 9(B), the driving accuracy of the optical system block unit 100 can be improved and accuracy errors can be further reduced, thereby improving the position control accuracy of the optical system block unit 100.

[0065] Furthermore, according to this embodiment, the first guide groove 11a to the third guide groove 11c are linear grooves arranged along the optical axis OA, and the optical system block unit 100 has front protrusions 112a to 112c and rear protrusions 113a to 113c that protrude radially outward and are guided along the linear grooves, thereby enabling the optical system block unit 100 to be guided along the optical axis OA.

[0066] Furthermore, according to this embodiment, the optical system block 100 has front bearings 102a to 102c that can rotate around the centers of the front protrusions 112a to 112c and rear bearings 103a to 103c that can rotate around the centers of the rear protrusions 113a to 113c.

[0067] This reduces the load on the stepping motor 301 when the optical system block unit 100 moves in the optical axis OA direction, thereby improving the position control accuracy of the optical system block unit 100.

[0068] Furthermore, according to this embodiment, the first guide groove 11a to the third guide groove 11c include the first guide groove 11a and the second guide groove 11b that are arranged on the second straight line LN2, and the third guide groove 11c that is different from the first guide groove 11a and the second guide groove 11b. Because the optical system block 100 is supported by three guide members, the strength of the lens barrel 2 against impact can be increased compared to, for example, a case in which the optical system block 100 is supported by two or less guide members.

[0069] The third guide groove 11c is also located on the first straight line LN1. In other words, the third guide groove 11c is located opposite the lead screw 302 (180° apart) in a plane perpendicular to the optical axis OA. The third guide groove 11c contributes to yaw-direction play in FIG. 9A , but due to the relative positions of the fulcrums, it does not affect drive performance near the optical axis center. Furthermore, even in the drive performance of the peripheral area away from the optical axis, because the third guide groove 11c is oriented vertically in FIG. 9A , minimal play is required, and yaw-direction play is also small, so it does not affect the drive accuracy of the optical system block 100. Therefore, the optical system block 100 can be supported without significantly affecting the drive accuracy of the optical system block 100, thereby increasing the impact resistance of the lens barrel 2.

[0070] Furthermore, in this embodiment, when the lead screw 302 rotates, the annular member 303a moves in the direction of the axis AX1 of the lead screw 302 while rotating, so that the friction generated between the annular member 303a and the lead screw 302 becomes rolling friction. This reduces the load on the stepping motor 301 when moving the optical system block unit 100 in the axial direction of the lead screw 302, thereby improving the position control accuracy of the optical system block unit 100.

[0071] Furthermore, according to this embodiment, the lens barrel 2 includes the lens holding frame F1 and the second fixed barrel member 13b that move relatively in the direction of the optical axis OA, and a first drip-proof member 91 and a second drip-proof member 92 that are provided in a gap between the lens holding frame F1 and the second fixed barrel member 13b that communicates between the outside and the inside of the lens barrel 2. In other words, the lens barrel 2 includes the lens holding frame F1 that holds the lens group L1, the second fixed barrel member 13b that is arranged radially outward of the lens holding frame F1 and whose position in the direction of the optical axis OA changes relatively with respect to the lens holding frame F1, and the first drip-proof member 91 and the second drip-proof member 92 that are provided in the gap between the lens holding frame F1 and the second fixed barrel member 13b.

[0072] This makes it possible to prevent water droplets from entering the interior of the lens barrel 2 from the outside of the lens barrel 2 through the gap between the lens holding frame F1 and the second fixed barrel member 13b, and also makes it possible to prevent light from entering through the gap between the lens holding frame F1 and the second fixed barrel member 13b.

[0073] Furthermore, in this embodiment, the first drip-proof member 91 has higher water repellency than the second drip-proof member 92. As a result, the water repellency of the first drip-proof member 91 can prevent water droplets from entering.

[0074] Furthermore, in this embodiment, the first drip-proof member 91 and the second drip-proof member 92 are arranged side by side in the direction of the optical axis OA, with the first drip-proof member 91 being arranged closer to the object than the second drip-proof member 92. In other words, the second drip-proof member 92 is arranged closer to the image plane than the first drip-proof member 91. As a result, even if there are water droplets that the first drip-proof member 91 was not able to prevent from entering, the second drip-proof member 92 can prevent the water droplets from entering further inside the lens barrel 2.

[0075] Furthermore, in this embodiment, the thickness T1 of at least a portion of the first drip-proof member 91 in a plane perpendicular to the optical axis is greater than the thickness T2 of at least a portion of the second drip-proof member 92. By making the thickness T1 of the first drip-proof member 91 arranged on the object side greater than the thickness T2 of the second drip-proof member 92, it is possible to effectively prevent water droplets from entering from the object side of the gap between the lens holding frame F1 and the second fixed barrel member 13b.

[0076] Furthermore, in this embodiment, a gap is provided between the first drip-proof member 91 and the lens holding frame F1. This reduces the load on the stepping motor 301 compared to when the first drip-proof member 91 and the lens holding frame F1 come into contact with each other, thereby improving the position control accuracy of the optical system block unit 100.

[0077] In the above embodiment, the stepping motor 301 is used as a drive source for rotating the lead screw 302. However, instead of the stepping motor 301, an ultrasonic motor, a VCM motor, or the like may be used. Also, a position detection unit may be provided to perform feedback control.

[0078] In the above embodiment, the first to third guide grooves 11a to 11c are engaged with the first to third groove engaging portions 101a to 101c, but the linear guide mechanism may be a combination of a shaft-shaped guide bar and an engaging portion that engages with the guide bar. In this case, two or more linear guide mechanisms are required, and two linear guide mechanisms may be disposed on the second straight line LN2.

[0079] In the above embodiment, the front bearings 102a to 102c and the rear bearings 103a to 103c are engaged with the first guide groove 11a to the third guide groove 11c in the first groove engagement portion 101a to the third groove engagement portion 101c, but the front bearings 102a to 102c and the rear bearings 103a to 103c may be omitted, and the front protrusions 112a to 112c and the rear protrusions 113a to 113c may be engaged with the first guide groove 11a to the third guide groove 11c. Also, one of the front bearing 102a and the rear bearing 103a may be omitted, one of the front bearing 102b and the rear bearing 103b may be omitted, or one of the front bearing 102c and the rear bearing 103c may be omitted. In particular, even if at least one of the front bearing 102c and the rear bearing 103c is omitted, the effect of suppressing the tilting of the moving part 20 can be maintained because the first guide groove 11a and the second guide groove 11b are arranged on the second straight line LN2.

[0080] In the above embodiment, the first guide groove 11a and the second guide groove 11b are disposed on the second straight line LN2. However, they may be disposed at positions offset from the second straight line LN2 within a predetermined range. For example, in a plane perpendicular to the optical axis OA, it is sufficient that at least a portion of the first guide groove 11a is disposed on the second straight line LN2, and at least a portion of the second guide groove 11b is also disposed on the second straight line LN2. Specifically, in a plane perpendicular to the optical axis OA, it is sufficient that the angle formed between the second straight line LN2 and a line connecting the optical axis OA and the center of the first guide groove 11a is within a range of ±15°. Furthermore, it is sufficient that the angle formed between the second straight line LN2 and a line connecting the optical axis OA and the center of the second guide groove 11b is within a range of ±15°.

[0081] Furthermore, in the above embodiment, the third guide groove 11c may be omitted. Furthermore, although the third guide groove 11c is disposed on the first straight line LN1, it may be disposed at a position offset from the first straight line LN1 within a predetermined range. For example, in a plane perpendicular to the optical axis OA, it is sufficient that at least a portion of the third guide groove 11c is disposed on the first straight line LN1. Specifically, in a plane perpendicular to the optical axis OA, it is sufficient that the angle formed between the first straight line LN1 and a line connecting the optical axis OA and the center of the third guide groove 11c is within a range of ±15°.

[0082] Furthermore, in the above embodiment, the drip-proof structure 90 has two drip-proof members, the first drip-proof member 91 and the second drip-proof member 92, but it may also have three or more drip-proof members.

[0083] In addition, in the above embodiment, the first drip-proof member 91 was positioned closer to the object than the second drip-proof member 92 in the direction of the optical axis OA, but the second drip-proof member 92 may also be positioned closer to the object than the first drip-proof member 91.

[0084] In the above embodiment, the case where the focusing method of the lens barrel 2 is the entire extension method has been described, but the configuration according to this embodiment can also be adopted when the focusing method of the lens barrel 2 is other than the entire extension method. For example, even if the lens groups L1 and L2 included in the optical system block 100 are of an inner focus type, which is an intermediate part within the imaging optical system, the optical system block 100 may be supported by the first guide groove 11a to the third guide groove 11c.

[0085] In the above embodiment, the first drip-proof member 91 and the second drip-proof member 92 are provided between the lens holding frame F1 and the second fixed barrel member 13b, which are relatively movable in the optical axis OA direction but do not rotate in the circumferential direction. However, the present invention is not limited to this. For example, the drip-proof structure 90 may be applied to a gap between two frames that are relatively movable in the optical axis OA direction but rotate in the circumferential direction, such as a gap between the lens holding frame and the focus operation ring.

[0086] 8, the stepping motor 301 is positioned above the center of the optical axis, but this can be changed as appropriate depending on the positional relationship with other members inside the lens barrel 2. For example, it is preferable to position the stepping motor 301 in a position where it does not interfere with the electrical contacts between the lens barrel 2 and the camera body 3, or with a circuit board that is positioned perpendicular to the optical axis.

[0087] 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.

[0088] REFERENCE SIGNS LIST 1 camera 2 lens barrel 13 fixed barrel 13a first fixed barrel member 13b second fixed barrel member 11a to 11c first to third guide grooves 20 moving portion 82 second biasing member 91 first drip-proof member 92 second drip-proof member 100 optical system block portion 101a to 101c first to third groove engaging portions 102a to 102c front bearings 103a to 103c rear bearings 112a to 112c front protrusions 113a to 113c rear protrusions 300 driving mechanism 301 stepping motor 302 lead screw 303a annular member L1, L2 lens group F1 lens holding frame LN1 first straight line LN2 second straight line OA optical axis AX1 axis

Claims

1. a first frame that holds the lens; a drive unit including a drive shaft and configured to drive the first frame in the optical axis direction; a second frame having at least two guide portions that guide the drive of the first frame in the optical axis direction; Equipped with In a plane perpendicular to the optical axis, at least one of the at least two guide portions is disposed on a second line perpendicular to a first line passing through the drive shaft and the optical axis and passing through the optical axis. Lens barrel.

2. At least one of the at least two guide portions has a linear groove arranged along the optical axis direction, the first frame has a protrusion that protrudes outward from an outer periphery and is guided along the linear groove; The lens barrel according to claim 1 .

3. The bottom surface of the linear groove on the object side in the optical axis direction is located on the outer diameter side of the bottom surface of the linear groove on the image plane side. The lens barrel according to claim 2 .

4. the first frame has a rotatable rotating portion provided on the protrusion, The lens barrel according to claim 2 .

5. the rotating portion has an inner ring fixed to the protrusion and an outer ring rotatable relative to the inner ring, The outer peripheral surface of the outer ring abuts against the linear groove. The lens barrel according to claim 4.

6. the at least two guide portions include first and second guide portions arranged on the second straight line, and a third guide portion different from the first and second guide portions; The lens barrel according to claim 1 .

7. The third guide portion is disposed on the first straight line. The lens barrel according to claim 6.

8. The drive unit is A lead screw and an annular member; a moving member that rotatably holds the annular member and moves in the axial direction of the lead screw as the lead screw rotates; a biasing portion that biases the annular member toward the lead screw in a direction perpendicular to the axial direction of the lead screw; having The lens barrel according to claim 1 .

9. a first frame that holds the lens; a drive unit including a drive shaft and configured to drive the first frame in the optical axis direction; a second frame having at least two guide portions that guide the drive of the first frame in the optical axis direction; an inner ring fixed to the first frame; an outer ring rotatable relative to the inner ring; Equipped with The outer peripheral surface of the outer ring abuts against the guide portion. Lens barrel.

10. A lens barrel including a first frame and a second frame that move relatively in an optical axis direction, at least two drip-proof members are provided in a gap between the first frame and the second frame, the gap communicating between the outside and the inside of the lens barrel; Lens barrel.

11. the first frame holds a lens; The second frame is disposed on the outer circumferential side of the first frame. The lens barrel according to claim 10.

12. the at least two drip-proof members include a first drip-proof member and a second drip-proof member, The first drip-proof member has higher water repellency than the second drip-proof member. The lens barrel according to claim 10 or 11.

13. the first drip-proof member and the second drip-proof member are arranged side by side in the optical axis direction, the first drip-proof member is disposed closer to the object side than the second drip-proof member; The lens barrel according to claim 12.

14. the first drip-proof member and the second drip-proof member are arranged side by side in the optical axis direction, the second drip-proof member is disposed closer to the object side than the first drip-proof member; The lens barrel according to claim 12.

15. the first drip-proof member and the second drip-proof member are arranged side by side in the optical axis direction, The thickness of at least a portion of the first drip-proof member is greater than the thickness of at least a portion of the second drip-proof member. The lens barrel according to claim 12.

16. the first frame is movable relative to the second frame in the optical axis direction, and the first frame and the second frame do not rotate relative to each other in the circumferential direction; The lens barrel according to claim 12.

17. A gap is provided between the first drip-proof member and the first frame. The lens barrel according to claim 12.

18. A first frame for holding a lens; a drive unit including a drive shaft and configured to drive the first frame in the optical axis direction; a second frame having at least two guide portions that guide the drive of the first frame in the optical axis direction; Equipped with the two guide portions are arranged in two regions separated by a first straight line passing through the drive shaft and the optical axis in a circumferential direction of the second frame, The drive unit and the drive shaft are arranged along the circumferential direction. Lens barrel.

19. An imaging device comprising the lens barrel according to any one of claims 1 to 11 and 18.