Lens barrel, imaging device, and drive device

Abstract

To heighten the performance of a drive mechanism that drives a focus lens.SOLUTION: A lens barrel comprises: a lens holding frame for holding a lens; a drive source; a lead screw in which a first thread groove is formed, and which is driven to rotate by the drive source; a bearing member including an inner ring having a groove that is in contact with the first thread groove, and an outer ring that rotates relatively to the inner ring; a movement member which is connected to the lens holding frame, and which holds the outer ring and moves in the axial direction of the lead screw along with rotation of the lead screw; and a bias unit that biases the bearing member toward the lead screw in a direction orthogonal to the axial direction of the lead screw.SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

[0002] A mechanism for driving a focus lens using a lead screw and a nut engaged with the lead screw has been proposed (for example, Patent Document 1). There is a demand for higher performance of the driving mechanism for driving the focus lens.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] According to a first aspect, the lens barrel includes a lens holding frame that holds a lens, a drive source, a lead screw formed with a first thread groove and rotationally driven by the drive source, an annular member having a groove in contact with the first thread groove on its inner circumference, a moving member connected to the lens holding frame, rotatably holding the annular member, and moving in the axial direction of the lead screw as the lead screw rotates, and a biasing portion that biases the annular member toward the lead screw in a direction orthogonal to the axial direction of the lead screw.

[0005] According to a second aspect, the lens barrel includes a lens holding frame that holds a lens, a drive source, a lead screw formed with a thread groove and rotationally driven by the drive source, a rotating member having a groove in contact with the thread groove, a moving portion connected to the lens holding frame, rotatably holding the rotating member, and moving in the axial direction of the lead screw as the lead screw rotates, and a biasing portion that biases the rotating member toward the lead screw in a direction orthogonal to the axis of the lead screw.

[0006] According to the third aspect, the imaging device includes the above lens barrel.

[0007] According to the fourth aspect, the driving device includes a driving source, a lead screw formed with a thread groove and rotationally driven by the driving source, an annular member having a groove in contact with the thread groove on its inner circumference, a holding member that rotatably holds the annular member, and a biasing portion that biases the annular member toward the lead screw in a direction orthogonal to the axis of the lead screw. With the rotation of the lead screw, the annular member moves in the axial direction of the lead screw while rotating together with the holding member.

[0008] Note that the configuration of the embodiments described below may be appropriately improved, and at least a part thereof may be replaced with other components. Furthermore, constituent elements with no particular limitation on their arrangement are not limited to the arrangements disclosed in the embodiments, and can be arranged at positions where their functions can be achieved.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

MODE FOR CARRYING OUT THE INVENTION

[0010] Hereinafter, the lens barrel according to the embodiment will be described in detail with reference to the drawings. In the drawings shown below, for ease of explanation and understanding, an XYZ orthogonal coordinate system is appropriately provided. In this coordinate system, when the photographer takes a horizontally long image with the optical axis OA horizontal, the direction from the subject toward the camera body 3 side at the camera position (hereinafter referred to as the normal position) is defined as the +Z direction. Also, the direction toward the right side as viewed from the camera body 3 side at the normal position is defined as the +X direction. Further, the direction toward the upper side at the normal position is defined as the +Y direction. Note that the shapes, lengths, thicknesses, etc. of the respective parts shown in the embodiment do not necessarily match the actual objects, and in each figure, for ease of understanding, the illustration of some elements may be omitted. Also, in the cross-sectional view, the hatching of some elements may be omitted.

[0011] <<First Embodiment>> FIGS. 1(A) and 1(B) are cross-sectional views showing the configuration of a camera 1 including a lens barrel 2 according to the first embodiment. FIGS. 1(A) and 1(B) have different cutting positions.

[0012] As shown in FIGS. 1(A) and 1(B), the camera 1 includes a camera body 3 and a lens barrel 2. The lens barrel 2 is provided with a lens mount LM at the rear part (base end part), and is detachably attached to the camera body 3 by engaging with a body mount (not shown) of the camera body 3. In the present embodiment, the lens barrel 2 is detachable from the camera body 3, but is not limited thereto, and the lens barrel 2 and the camera body 3 may be integrated.

[0013] The camera body 3 includes an imaging element IS and a control unit (not shown) etc. inside. The imaging element IS is constituted by 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.

[0014] The control unit includes a CPU (Central Processing Unit) or the like, and comprehensively controls the operation of the entire camera 1 related to shooting including focusing drive in the camera body 3 and the attached lens barrel 2.

[0015] As shown in FIGS. 1(A) and 1(B), the lens barrel 2 according to the present embodiment has lens groups L1 and L2 sequentially arranged along a common optical axis OA. The lens group L1 is held by a fixed barrel 10 provided in the lens barrel 2, and the lens group L2 is held by a lens holding frame F2. The lens group L2 is a focus lens group that moves in the direction of the optical axis OA during focusing.

[0016] Note that the lens barrel 2 is not limited to a single-focus lens, and may be a so-called zoom lens whose focal length can be changed. Also, each of the lens groups L1 and L2 may be composed of one lens or a plurality of lenses. In addition, although a lens barrel composed of two lens groups will be described as an example, there may be three or more lens groups.

[0017] The lens holding frame F2 is driven by a drive source unit 200. Hereinafter, the lens holding frame F2 and the drive source unit 200 will be described in detail.

[0018] FIG. 2(A) is a perspective view of the lens holding frame F2 and the drive source unit 200 as viewed from the subject side (-Z direction), and FIG. 2(B) is an enlarged view of the vicinity of a first guide portion 210 described later as viewed from the +Y direction.

[0019] As shown in FIG. 2(A), the lens holding frame F2 has a cylindrical portion 230 that holds the lens group L2, and a first guide portion 210 and a second guide portion 215 are provided on the outer peripheral portion of the cylindrical portion 230.

[0020] As shown in FIGS. 1(B) and 2(A), a guide bar 301 is inserted into the first guiding part 210. The guide bar 301 is fixed to the fixed cylinder 10, extends in the direction of the optical axis OA, and guides the lens holding frame F2 in the direction of the optical axis OA. On the other hand, a rotation restricting bar 302 is inserted into the second guiding part 215. The rotation restricting bar 302 is fixed to the fixed cylinder 10, extends in the direction of the optical axis OA, and restricts the movement of the lens holding frame F2 in the rotational direction.

[0021] As shown in FIG. 2(B), the first supporting parts 211a and 211b extend from the first guiding part 210 in the -X direction. The first supporting part 211a and the second supporting part 211b support the moving part 203 of the drive source unit 200 (details will be described later).

[0022] Next, the drive source unit 200 will be described. As shown in FIG. 2(A), the drive source unit 200 includes a stepping motor 201, a lead screw 202, a moving part 203 that moves along the axis of the lead screw 202 as the lead screw 202 rotates, and a mounting member 205.

[0023] FIG. 3(A) is a perspective view for explaining the configuration of the drive source unit 200, and FIG. 3(B) is a cross-sectional view of the drive source unit 200.

[0024] As shown in FIGS. 3(A) and 3(B), the mounting member 205 has a first part 205a fixed to the stepping motor 201, a second part 205b facing the first part 205a, and a third part 205c extending parallel to the lead screw 202 between the first part 205a and the second part 205b. A plurality of holes 205d are formed in the third part 205c. By attaching the mounting member 205 to the fixed cylinder 10 through the holes 205d with screws or the like, the drive source unit 200 is fixed to the fixed cylinder 10.

[0025] One end of the lead screw 202 is directly connected to the output shaft of the stepping motor 201, and the other end of the lead screw 202 is rotatably supported by the second portion 205b of the attachment member 205. The attachment member 205 is attached to the fixed cylinder 10 so that the axial direction AX1 of the lead screw 202 is parallel to the optical axis OA direction.

[0026] The moving part 203 moves in the axial direction AX1 of the lead screw 202 as the lead screw 202 rotates. FIG. 4(A) is an exploded perspective view of the moving part 203, FIG. 4(B) is a partial cross-sectional view of the moving part 203, FIG. 4(C) is a perspective view of the moving part 203, FIG. 4(D) is a perspective view of the spring 250, and FIG. 4(E) is a cross-sectional view of the moving part 203.

[0027] As shown in FIGS. 4(A) and 4(B), the moving part 203 includes a housing part 203a, a connecting part 203b, and a spring support part 203c.

[0028] As shown in FIG. 4(A), an annular member 220, a bearing 221, a spacer 222, and a magnet 223 are accommodated in the housing part 203a. The bearing 221 is not limited to a bearing, and any rotatable rolling body like a bearing may be used.

[0029] The annular member 220 has a groove 240 on its inner peripheral surface that contacts the thread groove 202a of the lead screw 202. The groove 240 is a circumferential groove formed over the entire circumference of the inner periphery of the annular member 220. The annular member 220 also has a base part 220a and a fitting part 220b. As shown in FIG. 4(E), the fitting part 220b fits into the inner ring of the bearing 221. The bearing 221 and the annular member 220 may be integrated.

[0030] As shown in FIG. 4(E), the outer ring of the bearing 221 fits into the inner wall of the housing part 203a. Thereby, the annular member 220 is rotatably held by the moving part 203. That is, the moving part 203 rotatably holds the annular member 220.

[0031] As shown in FIG. 4(E), the spacer 222 is provided to cover the outer ring of the bearing 221. The magnet 223 is provided to face the bearing 221 via the spacer 222. Since the outer ring of the bearing 221 is covered by the spacer 222, the inner ring of the bearing 221 is urged in the axial direction (the direction of the optical axis OA) by the magnet 223. Thereby, the axial play due to the axial clearance inside the bearing 221 can be suppressed. Note that the spacer 222 may be provided to cover the inner ring of the bearing 221, and the outer ring of the bearing 221 may be urged in the axial direction by a magnet. Also, if the axial play of the bearing 221 is within the required accuracy, the magnet 223 may be omitted. Further, instead of the magnet 223, a biasing member such as a spring may be used to suppress the axial play.

[0032] Also, as shown in FIG. 4(B), the moving part 203 has supported parts 203f and 203g that are respectively supported by the first support part 211a and the second support part 211b of the lens holding frame F2. Note that the supported parts 203f and 203g of the moving part 203 are respectively supported by the first support part 211a and the second support part 211b such that the axis AX2 of the spring support part 203c is parallel to the optical axis OA.

[0033] In a state where the supported parts 203f and 203g are respectively supported by the first support part 211a and the second support part 211b, the end face 203b1 of the connection part 203b of the moving part 203 abuts against the first support part 211a of the lens holding frame F2 (see FIG. 2(B)).

[0034] The spring support part 203c passes through the spring 250 and supports the spring 250. Thereby, the spring 250 is positioned between the connection part 203b of the moving part 203 and the second support part 211b of the lens holding frame F2 (see FIG. 2(B)).

[0035] As shown in FIG. 4(D), the spring 250 has a coil spring portion 250a and a torsion spring portion 250b. As shown in FIG. 2(B), one end of the coil spring portion 250a abuts against the connecting portion 203b of the moving portion 203, and the other end abuts against the second support portion 211b of the lens holding frame F2. Thereby, the coil spring portion 250a biases the connecting portion 203b of the moving portion 203 and the second support portion 211b of the lens holding frame F2 in a direction away from each other. Since the connecting portion 203b of the moving portion 203 is pressed against the first support portion 211a of the lens holding frame F2 by the coil spring portion 250a, when the moving portion 203 moves in the optical axis OA direction, the lens holding frame F2 also moves in the optical axis OA direction.

[0036] The torsion spring portion 250b is locked to a locking portion 203d (see FIG. 4(C)) formed on the outer periphery of the moving portion 203. Thereby, as shown by an arrow AR3 in FIG. 4(E), the annular member 220 is biased toward the lead screw 202 in a direction orthogonal to the axis AX1 of the lead screw 202. Since the groove 240 of the annular member 220 is pressed against the thread groove 202a of the lead screw 202, the play between the annular member 220 and the lead screw 202 is suppressed.

[0037] As shown in FIG. 4(B), the bottom portion 203e of the accommodating portion 203a of the moving portion 203 is inclined with respect to a plane perpendicular to the axis AX2 of the spring support portion 203c. Thereby, the axial direction AX3 of the annular member 220, the bearing 221, the spacer 222, and the magnet 223 is not parallel to the axial direction AX2 of the spring support portion 203c (the axial direction AX1 of the lead screw 202). This will be described in more detail.

[0038] FIG. 5(A) is a view of the lead screw 202 and the annular member 220 seen from the -Z direction, FIG. 5(B) is a view of the lead screw 202 and the annular member 220 seen from the biasing direction of the annular member 220 (the direction indicated by an arrow AR3 in FIG. 5(A)), and FIG. 5(C) is a cross-sectional view taken along line B-B of FIG. 5(A).

[0039] As shown in FIG. 5(B), in the present embodiment, the annular member 220 is inclined in accordance with the lead angle α of the lead screw 202. That is, the angle β formed by the axis AX1 of the lead screw 202 and the axis AX3 of the annular member 220 is substantially equal to the lead angle α.

[0040] As shown in FIG. 5(C), the annular member 220 and the lead screw 202 are in contact with each other on one side of the lead screw 202 and separated from each other on the other side in the biasing direction of the spring 250. The lead screw 202 has a first flank surface 202b and a second flank surface 202c that face each other in the direction of the axis AX1. The groove 240 formed in the inner circumference of the annular member 220 includes a first groove 240a and a second groove 240b. The first groove 240a and the second groove 240b are circumferential grooves formed over the entire circumference of the inner circumference of the annular member 220. The first groove 240a abuts against the first flank surface 202b at the contact point indicated by the arrow AR6 in FIGS. 5(A) and 5(B). On the other hand, the second groove 240b abuts against the second flank surface 202c at the contact point indicated by the arrow AR5 in FIGS. 5(A) and 5(B). That is, the groove 240 includes the first groove 240a and the second groove 240b, which have different phases from each other. Note that the enlarged views indicated by reference numerals C1 and C2 in FIG. 5(C) are cross-sectional views at the contact points indicated by the arrows AR6 and AR5 in FIGS. 5(A) and 5(B), respectively.

[0041] In this way, due to the fact that the annular member 220 is inclined in accordance with the lead angle α of the lead screw 202, and the structures of the first groove 240a and the second groove 240b, the annular member 220 and the lead screw 202 are in contact at at least two points indicated by the arrows AR5 and AR6 in FIGS. 5(A) and 5(B). The positions of the two points where the annular member 220 and the lead screw 202 are in contact are different in the direction of the axis AX1 of the lead screw 202 and in the direction orthogonal to the axis AX1 direction when viewed from the biasing direction in which the spring 250 biases the annular member 220. Thereby, the posture of the annular member 220 with respect to the lead screw 202 is stably maintained. Note that in FIG. 5(A), the contact point indicated by the arrow AR5 and the contact point indicated by the arrow AR6 are not actually on the same plane, but are shown on the same plane for ease of understanding.

[0042] Also, as described above, the groove 240 of the annular member 220 includes a first groove 240a and a second groove 240b that are out of phase with each other. Thereby, when the annular member 220 moves in either the subject side or the camera body 3 side direction in the optical axis OA direction, either the first groove 240a or the second groove 240b is in contact with the thread groove 202a of the lead screw 202 (since no gap is generated between the annular member 220 and the thread groove 202a of the lead screw 202), no delay occurs until the annular member 220 follows the lead screw 202. Thereby, the moving accuracy of the lens holding frame F2 in the optical axis OA direction can be improved, and the position control accuracy of the lens group L2 is improved.

[0043] Since the annular member 220 is rotatably supported via a bearing 221, when the lead screw 202 rotates, the annular member 220 is pushed by the first flank surface 202b or the second flank surface 202c of the thread groove 202a of the lead screw 202 and moves in the direction of the axis AX1 of the lead screw 202 while rotating. Thereby, since the moving part 203 that holds the annular member 220 also moves in the direction of the axis AX1 of the lead screw, the lens holding frame F2 connected to the moving part 203 can be moved in the optical axis OA direction.

[0044] When the annular member 220 is supported so as not to be rotatable, when the lead screw 202 rotates, the annular member 220 will not rotate and will be pushed against the first flank surface 202b or the second flank surface 202c of the thread groove 202a of the lead screw 202 and move in the direction of the axis AX1 of the lead screw. At this time, since sliding friction occurs between the annular member 220 and the lead screw 202, a load due to the sliding friction is applied to the stepping motor 201.

[0045] On the other hand, when the annular member 220 is supported so as to be rotatable as shown in the first embodiment, when the lead screw 202 rotates, the annular member 220 rotates around the axis AX1 of the lead screw 202, so the friction generated between the annular member 220 and the lead screw 202 becomes rolling friction. Since rolling friction is much smaller than sliding friction, the load applied to the stepping motor 201 when moving the moving part 203 in the direction of the axis AX1 can be reduced. Thereby, for example, when moving the lens holding frame F2 of the same weight using the stepping motor 201 of the same output, the lens holding frame F2 can be moved at a higher speed than when the annular member 220 is supported so as not to be rotatable (when sliding friction occurs). Also, for example, when using the stepping motor 201 of the same output, a heavier lens holding frame F2 can be moved than when the annular member 220 is supported so as not to be rotatable (when sliding friction occurs). Also, when moving the lens holding frame F2 of the same weight, since a stepping motor 201 with a smaller output can be used than when the annular member 220 is supported so as not to be rotatable (when sliding friction occurs), the drive source unit 200 can be miniaturized. In this way, the performance of the drive source unit 200 can be improved. Also, since the shape of the thread groove 202a of the lead screw 202 is different from the shape of the groove 240 of the annular member 220, when the lead screw 202 rotates, the annular member 220 can move in the direction of the axis AX1 of the lead screw 202 while rotating.

[0046] As described in detail above, according to the first embodiment, the lens barrel 2 includes a lens holding frame F2 that holds the lens group L2, a stepping motor 201, an annular member 220, a moving part 203, and a spring 250. The lead screw 202 has a thread groove 202a formed on its outer periphery and is rotationally driven by the stepping motor 201. The annular member 220 has a groove 240 on its inner periphery that abuts against the thread groove 202a. The moving part 203 is connected to the lens holding frame F2, rotatably holds the annular member 220, and moves in the direction of the axis AX1 of the lead screw 202 as the lead screw 202 rotates. The spring 250 biases the annular member 220 toward the lead screw in a direction orthogonal to the direction of the axis AX1 of the lead screw 202. The annular member 220 is rotatable about the axis AX1 of the lead screw 202 and rotates as the lead screw 202 rotates. Thus, as described above, when the annular member 220 moves in the direction of the axis AX1 as the lead screw 202 rotates, rolling friction occurs between the annular member 220 and the lead screw 202. Therefore, compared with the case where the annular member 220 is supported so that it cannot rotate (when sliding friction occurs), it is possible to increase the weight of the lens holding frame F2, miniaturize the drive source unit 200, or increase the speed of movement of the lens holding frame F2. In this way, the performance of the drive source unit 200 can be improved.

[0047] Also, in the first embodiment, the groove 240 of the annular member 220 is a circumferential groove formed over the entire inner circumference. Thereby, when the lead screw 202 rotates, the annular member 220 can be moved in the direction of the axis AX1 of the lead screw 202.

[0048] Further, in the first embodiment, the lead screw 202 has a first flank surface 202b and a second flank surface 202c that face each other in the direction of the axis AX1. The groove 240 of the annular member 220 has a first groove 240a that abuts against the first flank surface 202b and a second groove 240b that abuts against the second flank surface 202c. Thus, when the annular member 220 moves in either the subject side or the camera body 3 side direction in the optical axis OA direction, either the first groove 240a or the second groove 240b is in contact with the thread groove 202a of the lead screw 202 (since no gap is generated between the thread groove 202a of the lead screw 202), and no delay occurs until the annular member 220 follows the lead screw 202. Therefore, the movement accuracy of the lens holding frame F2 in the optical axis OA direction can be improved, and the position control accuracy of the lens group L2 is improved. In this way, the driving source unit 200 can be made to have higher performance.

[0049] Further, in the first embodiment, the annular member 220 is tilted in accordance with the lead angle α of the lead screw 202. Due to the annular member 220 being tilted in accordance with the lead angle α of the lead screw 202 and the structures of the first groove 240a and the second groove 240b, the thread groove 202a of the lead screw 202 and the groove 240 of the annular member 220 abut at at least two points. When viewed from the biasing direction in which the spring 250 biases the annular member 220, the positions of at least two points where the thread groove 202a of the lead screw 202 and the groove 240 of the annular member 220 abut are different in the axis AX1 direction of the lead screw 202 and in the direction orthogonal to the axis AX1 direction. Thereby, since the posture of the annular member 220 with respect to the lead screw 202 is stably maintained, the annular member 220 can be stably moved.

[0050] Further, in the first embodiment, a magnet 223 that biases the inner ring of the bearing 221 in the optical axis OA direction is provided. Thereby, the axial play of the bearing 221 can be reduced.

[0051] In the first embodiment described above, the first groove 240a included in the groove 240 of the annular member 220 contacts the first flank surface 202b of the thread groove 202a of the lead screw 202, and the second groove 240b contacts the second flank surface 202c of the thread groove 202a. However, the first groove 240a may contact the second flank surface 202c, and the second groove 240b may contact the first flank surface 202b.

[0052] In the first embodiment described above, the groove 240 was formed on the inner circumference of the annular member 220, but a thread groove may be formed instead. In this case, by making the pitch of the thread groove 202a of the lead screw 202 different from the pitch of the thread groove of the annular member 220, as the lead screw 202 rotates, the annular member 220 can move in the direction of the axis AX1 of the lead screw 202 while rotating, so the same effect as in the first embodiment can be achieved.

[0053] 《Second Embodiment》 In the second embodiment, the configuration when the annular member 220A has a groove 241 on its outer circumference will be described.

[0054] FIG. 6(A) is a perspective view showing the drive source unit 200A according to the second embodiment, and FIG. 6(B) is a plan view of the drive source unit 200A and the lens holding frame F2A according to the second embodiment as viewed from the subject side. FIG. 7(A) is a view of a part of the drive source unit 200A as viewed from the subject side (-Z direction), and FIG. 7(B) is a cross-sectional view taken along line E-E of FIG. 6(B). FIG. 8 is a cross-sectional view taken along line F-F of FIG. 6(B). In the following embodiments, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed descriptions thereof are omitted.

[0055] As shown in FIG. 6(B), the lens holding frame F2A according to the second embodiment is different from the lens holding frame F2 according to the first embodiment in that it does not have the first support portion 211a and the second support portion 211b extending in the -X direction from the first guide portion 210. In FIG. 6(B), the illustration of the stepping motor 201 and the attachment member 205 of the drive source unit 200A is omitted.

[0056] As shown in Fig. 6(A), the drive source unit 200A includes a stepping motor 201, a lead screw 202, a pair of moving parts 203A, a mounting member 205, and a tension spring 250A.

[0057] The pair of moving parts 203A face each other with the lead screw 202 interposed therebetween. Each of the pair of moving parts 203A has a connecting part 203i connected to the lens holding frame F2A and a holding part 203h that rotatably holds the annular member 220A.

[0058] As shown in Fig. 7(A), the connecting part 203i has a through hole 203k that penetrates the connecting part 203i in the direction of the optical axis OA (Z-axis direction). As shown in Fig. 8, the connecting shaft 216c of the lens holding frame F2A is inserted into the through hole 203k, and a cap part 216b is fixed to the end of the connecting shaft 216c. Thereby, the lens holding frame F2A and the moving part 203A are connected.

[0059] As shown in Fig. 7(A), the holding part 203h holds the bearing 221 by fitting with the inner ring of the bearing 221, and the outer ring of the bearing 221 is fitted with the inner periphery of the annular member 220A. Thereby, the moving part 203A rotatably holds the annular member 220A. Since the pair of moving parts 203A face each other with the lead screw 202 interposed therebetween, the pair of annular members 220A sandwich the lead screw 202.

[0060] As shown in Fig. 7(B), a groove 241 that contacts the thread groove 202a of the lead screw 202 is formed on the outer periphery of the annular member 220A. The groove 241 includes a first groove 241a that abuts against the first flank surface 202b of the thread groove 202a and a second groove 241b that abuts against the second flank surface 202c. That is, the groove 241 includes the first groove 241a and the second groove 241b that are out of phase with each other. Thereby, similar to the first embodiment, it is possible to prevent the annular member 220A from being delayed until it follows the lead screw 202.

[0061] As shown in Fig. 7(A), at one end of each of the pair of moving parts 203A (the end on the +Y side), a locking part 203j for locking the tension spring 250A is formed. Since the pair of annular members 220A sandwich the lead screw 202, when the tension spring 250A is locked to the pair of locking parts 203j with the pair of connecting parts 203i connected to the lens holding frame F2A, as shown by the arrows AR11 and AR12 in Fig. 7(A), the pair of annular members 220A are respectively biased toward the lead screw 202. Thereby, the play between the annular member 220A and the lead screw 202 is suppressed.

[0062] When the lead screw 202 rotates, the two annular members 220A are respectively pushed against the first flank surface 202b or the second flank surface 202c of the thread groove 202a of the lead screw while rotating, and move in the direction of the axis AX1 of the lead screw 202 (that is, the direction of the optical axis OA). Also in the second embodiment, since the friction generated between the lead screw 202 and the annular member 220A is rolling friction, the load applied to the stepping motor 201 can be reduced as compared with the case where the annular member 220A does not rotate.

[0063] 《Third Embodiment》 In the third embodiment, the case where the two annular members 220C and 220D are arranged in the direction of the axis AX1 of the lead screw 202 will be described.

[0064] Fig. 9(A) is a perspective view of the drive source unit 200C according to the third embodiment, and Fig. 9(B) is a plan view of the drive source unit 200C and the lens holding frame F2C according to the third embodiment as viewed from the object side. Fig. 10(A) is a cross-sectional view of the drive source unit 200C, and Fig. 10(B) is a cross-sectional view of the moving parts 203C and 203D. Also, Fig. 11(A) is a plan view of the moving parts 203C and 203D according to the third embodiment as viewed from the -Z direction, and Fig. 11(B) is a cross-sectional view taken along the line D-D of Fig. 11(A). In Fig. 9(A), the illustration of the stepping motor 201 and the mounting member 205 is omitted.

[0065] As shown in FIGS. 9(A) and 10(A), the drive source unit 200C according to the third embodiment includes a stepping motor 201, a lead screw 202, annular members 220C and 220D, moving parts 203C and 203D, and torsion springs 250C and 250D.

[0066] As shown in FIG. 10(B), the moving part 203C includes a housing part 213a that houses the annular member 220C and the bearing 221, and a connection part 213b that connects to the lens holding frame F2C. The outer ring of the bearing 221 fits with the inner wall of the housing part 213a, and the outer periphery of the annular member 220C fits with the inner ring of the bearing 221. Thereby, the annular member 220C is rotatably held by the moving part 203C. A groove 240C that contacts the thread groove 202a of the lead screw 202 is formed on the inner periphery of the annular member 220C. The groove 240C contacts, for example, the first flank surface 202b of the thread groove 202a of the lead screw 202.

[0067] The bottom 213d of the housing part 213a is inclined according to the lead angle of the lead screw 202. Thereby, the annular member 220C is inclined according to the lead angle. For this reason, as described in the first embodiment, due to the annular member 220C being inclined according to the lead angle and the structure of the groove 240C of the annular member 220C, the lead screw 202 and the annular member 220C are in contact at at least two points, and the posture of the annular member 220C with respect to the lead screw 202 can be stably maintained.

[0068] A through hole 213c through which the connection shaft 212a of the lens holding frame F2C is inserted is provided in the connection part 213b. Further, a locking part 213e to which one end of the torsion spring 250C is locked is formed on the side surface of the moving part 203C.

[0069] As shown in FIG. 9(B), the torsion spring 250C is supported by the spring support shaft 212c of the lens holding frame F2C. One end is locked to the locking portion 213e of the moving portion 203C, and the other end abuts against the first regulating portion 214a of the lens holding frame F2C. Thereby, as shown by the arrow AR21 in FIG. 11(A), the torsion spring 250C biases the annular member 220C toward the lead screw 202 in a direction orthogonal to the axial direction AX1 of the lead screw 202. Thereby, as shown by the arrow AR21 in FIG. 11(B), the annular member 220C is pressed against the lead screw 202, and the play between the lead screw 202 and the annular member 220C is reduced.

[0070] As shown in FIG. 10(B), the moving portion 203D includes a housing portion 206a that houses the annular member 220D and the bearing 221, and a connecting portion 206b that connects to the lens holding frame F2C. The outer ring of the bearing 221 fits with the inner wall of the housing portion 206a, and the outer periphery of the annular member 220D fits with the inner ring of the bearing 221. Thereby, the annular member 220D is rotatably held by the moving portion 203D. A groove 240D that contacts the thread groove 202a of the lead screw 202 is formed on the inner periphery of the annular member 220D. The groove 240D contacts, for example, the second flank surface 202c of the thread groove 202a of the lead screw 202. Thereby, when the lead screw 202 rotates, either the groove 240C of the annular member 220C or the groove 240D of the annular member 220D is in contact with the thread groove 202a of the lead screw 202. Therefore, the same effects as the first groove 240a and the second groove 240b formed on the inner periphery of the annular member 220 according to the first embodiment can be obtained.

[0071] The bottom 206d of the housing portion 206a is inclined in accordance with the lead angle of the lead screw 202. As a result, the annular member 220D is inclined in accordance with the lead angle. For this reason, as described in the first embodiment, due to the annular member 220D being inclined in accordance with the lead angle and the structure of the groove 240D of the annular member 220, the lead screw 202 and the annular member 220D contact at at least two points, and the posture of the annular member 220D with respect to the lead screw 202 can be stably maintained.

[0072] Since the lead screw 202 and the annular member 220C contact at at least two points, and the lead screw 202 and the annular member 220D contact at at least two points, the contact points with the lead screw 202 are four points with different positions in the direction of the axis AX1 of the lead screw 202 and in the direction orthogonal to the axis AX1 direction. As a result, since the posture of the lens holding frame F2C is determined, in the third embodiment, the guide bar 301 may be omitted. Further, by arranging the annular member 220C and the annular member 220D with a phase shift in the axial direction, the axial play of the bearing 221 can be suppressed, and the play eliminating members such as the magnet 223 described in the first embodiment can be omitted.

[0073] The connection portion 206b is provided with a through hole 206c through which the connection shaft 212a of the lens holding frame F2C is inserted. Further, a locking portion 206e to which the torsion spring 250D is locked is formed on the side surface of the moving portion 203D.

[0074] As shown in FIG. 9(B), the torsion spring 250D is supported by the spring support shaft 212d of the lens holding frame F2C. One end is locked to the locking portion 206e of the moving portion 203C, and the other end is in contact with the second regulating portion 214b of the lens holding frame F2C. Thereby, as shown by the arrow AR22 in FIG. 11(A), the torsion spring 250D biases the annular member 220D toward the lead screw 202 in a direction orthogonal to the axial direction AX1 of the lead screw 202. As a result, as shown by the arrow AR22 in FIG. 11(B), the annular member 220D is pressed against the lead screw 202, and the play between the lead screw 202 and the annular member 220D is reduced.

[0075] A cap portion 212b is fixed to the end of the connecting shaft 212a of the lens holding frame F2C that passes through the through hole 213c of the moving portion 203C and the through hole 206c of the moving portion 203D. A compression coil spring 260 is provided between the moving portion 203C and the cap portion 212b, and biases the moving portion 203C and the cap portion 212b in a direction away from each other. Thereby, when the moving portions 203C and 203D move in the direction of the optical axis OA, the lens holding frame F2C can also move in the direction of the optical axis OA.

[0076] Also in the third embodiment, the annular member 220C rotatably held by the moving portion 203C and the annular member 220D rotatably held by the moving portion 203D move in the axial direction AX1 of the lead screw 202 while rotating when the lead screw 202 rotates. Since the friction generated between the lead screw 202 and the annular member 220C and between the lead screw 202 and the annular member 220D is rolling friction, the load applied to the stepping motor 201 can be reduced as compared with the case where the annular members 220C and 220D do not rotate.

[0077] In the third embodiment, it has been described that the groove 240C of the annular member 220C contacts the first flank surface 202b of the thread groove 202a of the lead screw 202, and the groove 240D of the annular member 220D contacts the second flank surface 202c of the thread groove 202a. However, the groove 240C may contact the second flank surface 202c, and the groove 240D may contact the first flank surface 202b.

[0078] <<Fourth Embodiment>> FIG. 12(A) is a perspective view of the drive source unit 200D according to the fourth embodiment, FIG. 12(B) is a perspective view showing a state where the moving part 203E is fixed to the lens holding frame F2D, and FIG. 12(C) is a view showing the moving part 203E and the lead screw 202 as viewed from the +Z direction. In the fourth embodiment, the shape of the moving part 203E is different from that of the moving part 203 according to the first embodiment.

[0079] As shown in FIG. 12(A), in the fourth embodiment, the moving part 203E is connected to the lens holding frame F2D by screws or the like. Further, the annular member 220 is biased toward the lead screw 202 in a direction orthogonal to the axis AX1 of the lead screw 202 by two torsion springs 250E. Since the other configurations are the same as those of the first embodiment, detailed description thereof is omitted. Also in the configuration according to the fourth embodiment, as the lead screw 202 rotates, the annular member 220 moves in the direction of the optical axis OA while rotating, so that the load on the stepping motor 201 can be reduced.

[0080] The above-described embodiments are preferred examples. However, the present invention is not limited thereto, and various modifications can be made without departing from the gist thereof, and any constituent elements may be combined.

Explanation of Reference Numerals

[0081] 1 Camera 2 Lens Barrel 3 Camera Body 201 Stepping Motor 202 Lead Screw 202a Thread groove 202b First flange surface 202c Second flange surface 203, 203A, 203C - 203E Moving part 220, 220A, 220C, 220D Annular member 221 Bearing 223 Magnet 250 Spring 250A Tension spring 250C, 250D, 250E Torsion spring L2 Lens group F2, F2A, F2C, F2D Lens holding frame

Claims

1. A lens holding frame for holding a lens, a drive source, a lead screw having a first thread groove formed therein and being rotationally driven by the drive source, a bearing member having an inner ring having a groove that abuts against the first thread groove, and an outer ring that rotates relative to the inner ring, a moving member connected to the lens holding frame, holding the outer ring, and moving in the axial direction of the lead screw as the lead screw rotates, a biasing portion that biases the bearing member toward the lead screw in a direction orthogonal to the axial direction of the lead screw, A lens barrel comprising the above.

2. The inner ring is rotatable about the axis of the lead screw, The lens barrel according to claim 1.

3. The inner ring rotates as the lead screw rotates, The lens barrel according to claim 1 or claim 2.

4. Comprising a magnet that biases a part of the bearing member in the optical axis direction, The lens barrel according to claim 1 or claim 2.

5. The groove is a circumferential groove formed over the entire circumference of the inner periphery of the inner ring, The lens barrel according to claim 1 or claim 2.

6. The groove is a second thread groove formed over the entire circumference of the inner periphery of the inner ring, The pitch of the first thread groove and the pitch of the second thread groove are different, The lens barrel according to claim 1 or claim 2.

7. The axial direction of the bearing member is inclined with respect to the axial direction of the lead screw, The lens barrel according to claim 1 or claim 2.

8. The inner ring and the lead screw are in contact on one side of the lead screw and separated on the other side of the lead screw in the biasing direction of the biasing portion, The lens barrel according to claim 1 or claim 2.

9. The first thread groove and the groove abut at at least two points, The lens barrel according to claim 1 or claim 2.

10. When viewed from the biasing direction in which the biasing portion biases the bearing member, the positions of the at least two points where the first thread groove and the groove abut are different in the axial direction of the lead screw and in the direction orthogonal to the axial direction of the lead screw, The lens barrel according to claim 9.

11. The first thread groove has a first flank surface and a second flank surface that face each other in the axial direction, The groove has a first groove that abuts against the first flange surface and a second groove that abuts against the second flange surface. The lens barrel according to claim 1 or claim 2.

12. A lens holding frame for holding a lens, A drive source, A lead screw formed with a thread groove and rotationally driven by the drive source, A bearing member having an outer ring having a groove that abuts against the thread groove and an inner ring that rotates relative to the outer ring, A moving part that is connected to the lens holding frame, holds the inner ring, and moves in the axial direction of the lead screw as the lead screw rotates, A biasing part that biases the bearing member toward the lead screw in a direction orthogonal to the axial direction of the lead screw, A lens barrel comprising the same.

13. An imaging device comprising the lens barrel according to claim 1 or claim 2.

14. A drive source, A lead screw formed with a thread groove and rotationally driven by the drive source, A bearing member having an inner ring having a groove that abuts against the thread groove and an outer ring that rotates relative to the inner ring, A holding member that rotatably holds the outer ring, A biasing part that biases the bearing member toward the lead screw in a direction orthogonal to the axis of the lead screw, Comprising, As the lead screw rotates, the inner ring moves in the axial direction of the lead screw together with the holding member while rotating, A drive device.

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