Driving device and optical instrument

Abstract

To reduce loss in driving a member to be driven by using a lead screw via a power transmission member meshing with the lead screw.SOLUTION: A driving device 100 has: a member to be driven 102 that is movable in a straight advance direction; a lead screw 106 that is driven to rotate by an actuator 105; and a power transmission member 107 that is supported by the member to be driven on an inner diameter side, meshes with the lead screw on an outer diameter side, and transmits, to the member to be driven, a driving force in the straight advance direction generated by the rotation of the lead screw. The power transmission member is supported to be rotatable with the rotation of the lead screw.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a drive device for driving a driven member. [Background technology]

[0002] Among the above-mentioned driving devices, there is one that rotates a lead screw using an actuator such as a DC motor or a stepping motor, and linearly drives a driven member via a rack that meshes with the lead screw or other power transmission members. Patent Document 1 discloses a configuration in which a steel ball is meshed with the lead screw, and a sliding member that holds the steel ball in a recess is connected to the driven member via a leaf spring. Patent Document 2 discloses a configuration in which a rack is meshed with the lead screw, and the rack is connected to the driven member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 01-010470 [Patent Document 2] JP 2001-215394 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the configuration of Patent Document 1, friction loss occurs at the contact surface between the steel balls that mesh with the lead screw and the sliding member. Also, in the configuration of Patent Document 2, friction loss occurs at the contact surface between the lead screw and the rack. For this reason, when driving a driven member with a large mass or at a large acceleration, a large load or inertial force acts on the contact surface, increasing friction loss, and it becomes necessary to increase the power applied to the actuator to increase its output or to enlarge the actuator.

[0005] The present invention provides a drive device capable of reducing loss when a driven member is driven by a lead screw via a power transmission member meshing with the lead screw. [Means for solving the problem]

[0006] A driving device according to one aspect of the present invention includes a driven member movable in a linear direction, a lead screw rotatably driven by an actuator, and a power transmission member supported by the driven member on its inner diameter side and meshing with the lead screw on its outer diameter side, for transmitting a linear driving force generated by rotation of the lead screw to the driven member. The power transmission member is supported so as to be rotatable together with the rotation of the lead screw. An optical device using the driving device also constitutes another aspect of the present invention. Effect of the Invention

[0007] According to the present invention, it is possible to reduce loss that occurs when a driven member is driven by a lead screw via a power transmission member that meshes with the lead screw. [Brief description of the drawings]

[0008] [Figure 1] 1A and 1B are a perspective view and a cross-sectional view showing a configuration of a lens driving device according to a first embodiment. [Diagram 2] FIG. 2 is a diagram showing details of the lens driving device according to the first embodiment. [Diagram 3] FIG. 2 is a diagram showing a power transmission member in the first embodiment. [Figure 4] 5A to 5C are diagrams illustrating a backlash and a contact state when the power transmission member is driven in the first embodiment. [Diagram 5] 6 is another diagram for explaining the backlash and contact state during driving of the power transmission member in the first embodiment. FIG. [Figure 6] 5A to 5C are diagrams for explaining the principle of loss reduction in the first embodiment. [Figure 7] 11A and 11B are a perspective view and a cross-sectional view showing the configuration of a lens driving device according to a second embodiment. [Figure 8] FIG. 11 is a partial cross-sectional view of the lens driving device according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, embodiments of the present invention will be described with reference to the drawings. EXAMPLES

[0010] Fig. 1(b) shows a lens driving device 100 according to the first embodiment. The lens driving device 100 is mounted on an optical device such as an interchangeable lens that can be attached to an imaging device or an imaging device with a lens barrel. Fig. 1(a) shows a part of the lens driving device 100.

[0011] 1(b), lens driving device 100 has a fixed member 101 having a hollow cylindrical shape, a lens frame 102 as a driven member disposed within the fixed member 101, and a main guide bar 103 and a sub guide bar 104 as guide means. Lens driving device 100 further has an actuator 105, a power transmission member 107, and an abutment member 108. The fixed member 101 is a part of the optical device.

[0012] The lens frame 102 as an optical element holding member holds a lens as an optical element (not shown). However, an optical element holding member that holds an optical element other than a lens (such as an aperture) may be used. The main guide bar 103 and the sub guide bar 104 are fixed in the fixed member 101 by having both ends held by bar fixing parts 101a and 101b provided on the inner surface of the fixed member 101. The sleeve part 102a of the lens frame 102 is engaged with the main guide bar 103 so as to be movable in the axial direction, and the rotation stop part 102b of the lens frame 102 is engaged with the sub guide bar 104 so as to be movable in the axial direction. The lens frame 102 is guided in the axial direction by the main guide bar 103 at the sleeve part 102a. Furthermore, the rotation stop part 102b is engaged with the sub guide bar 104 so as to be movable in the axial direction, thereby preventing the lens frame 102 from rotating around the main guide bar 103.

[0013] Actuator 105 is a rotary drive source such as a stepping motor, and is fixed to fixed member 101. A lead screw 106 is provided on the output shaft of actuator 105. The axial direction of lead screw 106 is parallel to the axial directions of main guide bar 103 and sub guide bar 104, and in the following description, these axial directions are referred to as the optical axis direction. In addition, in the optical axis direction, the side on which actuator 105 is provided is referred to as the rear side, and the side from which lead screw 106 extends from actuator 105 is referred to as the front side. The front end of lead screw 106 is rotatably held by holding plate 109 fixed to actuator 105.

[0014] Fig. 2(a) shows the details of the shape of the lens frame 102. Fig. 2(b) shows an enlarged view of part A in Fig. 2(a). The lens frame 102 is provided with a support shaft portion 102d extending from the rear side to the front side. The support shaft portion 102d rotatably supports the power transmission member 107 shown in Figs. 1(a) and (b) on its inner diameter side.

[0015] The member corresponding to the support shaft portion 102d may be manufactured as a separate member from the lens frame 102 and fixed to the lens frame 102 by adhesive or other methods. In this case, another member may be interposed between the lens frame 102 and the member corresponding to the support shaft portion 102d. In such a case, the power transmission member 107 can be considered to be supported by the lens frame 102.

[0016] Figures 3(a) to (c) show the details of the shape of the power transmission member 107. Figure 3(a) shows a state in which a plurality of teeth of the power transmission member 107, which will be described later, are engaged with the lead screw 106, and Figures 3(b) and 3(c) show the power transmission member 107 as viewed from the diagonal rear side and the diagonal front side, respectively.

[0017] The power transmission member 107 has a cylindrical base shape and has a plurality of teeth 107a, 107b, 107c, and 107d formed on its outer periphery (outer diameter side) at predetermined intervals in the optical axis direction. These teeth 107a to 107d extend over the entire circumference of the power transmission member 107 in the rotation direction, and always mesh with the threads of the lead screw 106 regardless of the rotation of the power transmission member 107.

[0018] As shown in Fig. 3(b), the power transmission member 107 is formed with a connecting portion 107e as a cylindrical recess with an open rear side. The support shaft portion 102d of the lens frame 102 is inserted into this connecting portion 107e (see Fig. 4(a)), so that the power transmission member 107 is supported rotatably around the support shaft portion 102d. The front end surface 102e of the support shaft portion 102d shown in Fig. 2(b) is a surface that can abut against the front end surface in the connecting portion 107e of the power transmission member 107.

[0019] The forward movement of the power transmission member 107 relative to the lens frame 102 (removal from the support shaft portion 102d) is prevented by abutment of a front end abutment portion 107f of the power transmission member 107, as shown in Figure 3(c), with an abutment member 108 fixed to the lens frame 102, as shown in Figures 1(a) and (b). Note that the abutment member 108 is manufactured as a separate member from the lens frame 102 and fixed to the lens frame 102, but even in this case, it can be considered that the power transmission member 107 abuts against the lens frame 102. Also, a portion equivalent to the abutment member 108 may be provided integrally with the lens frame 102.

[0020] In the above configuration, when the actuator 105 is driven to rotate the lead screw 106, the rotation of the lead screw 106 is converted into a driving force in the optical axis direction (linear direction) by the meshing of the lead screw 106 with the power transmission member 107. The power transmission member 107 transmits the driving force to the lens frame 102. As a result, the lens frame 102 is guided in the optical axis direction by the main guide bar 103 (and the sub guide bar 104) and driven linearly in the same direction.

[0021] The power transmission member 107 rotates relative to the lens frame 102 (support shaft portion 102d) while moving in the optical axis direction in mesh with the rotating lead screw 106. At this time, the rotational resistance (torque) generated by the coupling portion 107e of the power transmission member 107 sliding in the rotational direction relative to the support shaft portion 102d is defined as T1. In addition, the rotational resistance generated by the power transmission member 107 when the first to fourth teeth portions 107a to 107d of the power transmission member 107 slip against the thread of the lead screw 106 is defined as T2. The "slip" referred to here does not include minute (microscopic) slip that cannot be visually observed. In other words, the "slip" means a slip of a clear predetermined amount (for example, 3%) or more that can be visually confirmed.

[0022] In this case, the present embodiment satisfies the condition of the following formula (1).

[0023] Rotational resistance T1<Rotational resistance T2 (1) By satisfying the condition of formula (1), the power transmission member 107 can rotate relative to the lens frame 102 while meshing with the lead screw 106 without slipping on the threads of the lead screw 106.

[0024] Next, the relationship between the power transmission member 107 and the lead screw 106 when driving the lens frame 102, and the relationship between the power transmission member 107 and the lens frame 102 or the abutment member 108 will be described.

[0025] FIG. 4(a) shows a state in which the backlash between the above-mentioned components is eliminated when the lens frame 102 is driven in the direction G1. FIG. 4(b) shows an enlarged view of part B in FIG. 4(a). In the lead screw 106 that rotates in a rotation direction that drives the lens frame 102 in the direction G1, the thread appears to move in the direction G1. At this time, as shown in FIG. 4(b), the backlash between the thread of the lead screw 106 and the teeth of the power transmission member 107 is eliminated on the G1 side. In other words, the thread of the lead screw 106 abuts against the teeth of the power transmission member 107 from the direction G1. Furthermore, the power transmission member 107 abuts against the lens frame 102 (the front end surface 102e of the support shaft portion 102d), and thus the backlash between them is also eliminated. After the backlash is eliminated in this manner, the lens frame 102 is driven in the direction G1.

[0026] FIG. 5(a) shows a state in which the backlash between the above-mentioned components is eliminated when the lens frame 102 is driven in the direction G2. FIG. 5(b) shows an enlarged view of part C in FIG. 5(a). In the lead screw 106 that rotates in a rotation direction that drives the lens frame 102 in the direction G2, the thread appears to move in the direction G2. At this time, as shown in FIG. 5(b), the backlash between the thread of the lead screw 106 and the teeth of the power transmission member 107 is eliminated on the G2 side. That is, the thread of the lead screw 106 abuts against the teeth of the power transmission member 107 from the direction G2. Furthermore, the power transmission member 107 (front end abutment portion 107f) abuts against the abutment member 108, so that the backlash between them is also eliminated. After the backlash is eliminated in this manner, the lens frame 102 is driven in the direction G2.

[0027] Next, the forces that the power transmission member 107 receives when the lens frame 102 is driven and the losses due to these forces will be described. FIG. 6(a) shows the forces F1, F2, and F3 that the power transmission member 107 receives primarily when the lens frame 102 is driven in the direction G1. FIG. 6(b) shows a cross section taken along the cutting line I in FIG. 6(a). This figure shows a resistance force F4 against the rotation of the power transmission member 107 that occurs when the power transmission member 107 rotates in the direction G3 while receiving the force F2, and a tangential force F5 that occurs when the lead screw 106 rotates the power transmission member 107. FIG. 6(c) shows a cross section taken along the cutting line J in FIG. 6(a). This figure shows a resistance force F6 against the rotation of the power transmission member 107 that occurs when the power transmission member 107 rotates in the direction G3 while receiving the force F3. Details of the forces F1 to F3, the resistance force F4, the tangential force F5, and the resistance force F6 will be described later. 6(b) and (c), the diameter (inner diameter) of the coupling portion 107e of the power transmission member 107 is defined as D1. The diameter (outer diameter) of the support shaft portion 102d of the lens frame 102 is set to be slightly smaller than the diameter D1 of the power transmission member 107 so that the power transmission member 107 is allowed to rotate around the support shaft portion 102d. The diameter (effective diameter) of each tooth portion of the power transmission member 107 that meshes with the lead screw 106 is defined as D2, the diameter of the front end face 102e of the support shaft portion 102d of the lens frame 102 is defined as D3, and the diameter (effective diameter of the thread) of the lead screw 106 is defined as D0.

[0028] The force F1 is a force that the lead screw 106, to which torque from the energized actuator 105 is input, imparts to the power transmission member 107, and is generated in a direction perpendicular to the teeth (107a to 107d) of the power transmission member 107 with which the threads of the lead screw 106 abut. The force F1 increases when a lens frame 102 with a larger mass is driven or when the lens frame 102 is driven with a larger acceleration. Note that F1 is the resultant force of the forces that the first to fourth teeth 107a to 107d of the power transmission member 107 receive from the lead screw 106.

[0029] The force F2 is a force that the power transmission member 107 receives in a direction perpendicular to the direction G1 from the support shaft portion 102d of the lens frame 102. The force F3 is a force that the power transmission member 107 receives in the direction opposite to the direction G1 from the front end face 102e of the support shaft portion 102d of the lens frame 102.

[0030] 6(b) will be used to explain the rotational resistance around the rotational center axis X1 of the power transmission member 107 generated by the force F2. In a configuration that satisfies the condition of the above-mentioned formula (1), when the lead screw 106 rotates, the power transmission member 107 rotates with almost no slippage while meshing with the lead screw 106. At this time, when the power transmission member 107 rotates in the direction G3 while receiving the force F2, a resistance force F4 is generated between the power transmission member 107 and the lens frame 102 (support shaft portion 102d). If the rotational resistance (torque) around the rotational center axis X1 of the power transmission member 107 generated by the resistance force F4 is T4, the rotational resistance T4 is expressed by the following formula (2).

[0031] T4 = F4 × (D1 / 2) (2) On the other hand, if the tangential force F5 required for the lead screw 106 to rotate the power transmission member 107 receiving the rotational resistance T4 is given by the following formula (3).

[0032] F5>F4 / (D2 / D1) (3) From the above, if the rotational driving force required for the lead screw 106 to rotate the power transmission member 107 is denoted as T5, the rotational driving force T5 is expressed by the following formula (4).

[0033] T5 = F5 × (D0 / 2) (4) From equations (3) and (4), the rotational driving force T5 can be calculated by the following equation (5) using the resistance force F4.

[0034] T5>{F4 / (D2 / D1)}×(D0 / 2) (5) As can be seen from formula (5), the rotational driving force T5 required for the lead screw 106 to rotate the power transmission member 107 is reduced according to (D2 / D1). This means that the resistance force F4 at diameter D1 generated between the power transmission member 107 and the lens frame 102 is reduced by (D2 / D1) at the position of diameter D2 of the teeth of the power transmission member 107. Therefore, the tangential force F5 for the lead screw 106 to rotate the power transmission member 107 is reduced according to (D2 / D1).

[0035] However, if the diameter D2 is made too large, and (D2 / D1) becomes large, the tangential force F5 is reduced, but not only does the moment of inertia of the power transmission member 107 increase, but the lens driving device 100 also becomes large. For this reason, it is necessary to set (D2 / D1) appropriately. It is desirable that (D2 / D1) satisfies the condition of the following formula (6) so that the moment of inertia of the power transmission member 107 does not increase too much and the lens driving device 100 does not become large.

[0036] 1<(D2 / D1)<100 (6) The numerical range of formula (6) may be as follows: formula (6)'.

[0037] 1<(D2 / D1)<10 (6)′ Next, the rotational resistance around the rotational center axis X1 of the power transmission member 107 generated by the force F3 will be described with reference to Figures 6(a) and 6(c). When the power transmission member 107 rotates in the direction G3 while receiving the force F3, a resistance force F6 is generated between the power transmission member 107 and the lens frame 102 (the front end surface 102e of the support shaft portion 102d). At this time, if the rotational resistance (torque) around the rotational center axis X1 of the power transmission member 107 generated by the resistance force F6 is T6, the rotational resistance T6 is expressed by the following formula (7).

[0038] T6=F6×(D3 / 2) (7) At this time, by making the shape of the front end surface 102e of the support shaft portion 102d of the lens frame 102 a curved shape such as a spherical surface, the diameter D3 becomes almost 0, and the rotational resistance T6 also becomes almost 0. As a result, the rotational resistance T6 becomes a very small value. Furthermore, as described above, the resistance force F4 caused by the force F2 generated at the diameter D1 is reduced in accordance with (D2 / D1) at the position of the diameter D2. Similarly, the resistance force F6 at the diameter D3 generated between the power transmission member 107 and the lens frame 102 is reduced in accordance with (D2 / D3) at the position of the diameter D2 of the teeth of the power transmission member 107. Therefore, the rotational resistance T6 has almost no effect on the tangential force F5 for the lead screw 106 to rotate the power transmission member 107, and can be ignored.

[0039] Incidentally, it is also preferable that the front end contact portion 107f of the power transmission member 107, which contacts the contact member 108, has a curved shape such as a spherical surface.

[0040] Here, the difference in rotational resistance between the configuration of this embodiment and the conventional configuration (Patent Documents 1 and 2) will be described. In the conventional configuration that does not use the power transmission member 107 of this embodiment, the steel balls and racks that are the power transmission members directly mesh with the lead screw. Therefore, a resistance force such as friction is generated against the force equivalent to the force F1 shown in Fig. 6(a), and this resistance force becomes the tangential force of the lead screw that is required to rotate the power transmission member.

[0041] On the other hand, in this embodiment, the lead screw 106 and the power transmission member 107 rotate relative to each other with almost no slippage, so that no resistance force such as friction due to the force F1 occurs, and a resistance force F4 such as friction due to the force F2 occurs. As a result, the tangential force F5 of the lead screw 106 required to rotate the power transmission member 107 is reduced by reducing the resistance forces F4 and F6 according to (F1 / F2) and (D2 / D1). Therefore, in a configuration using the power transmission member 107 as in this embodiment, the load on the lead screw 106 (that is, the actuator 105) can be reduced according to (F1 / F2) and (D2 / D1). In other words, the loss when transmitting the driving force from the lead screw 106 to the power transmission member 107 can be reduced. Therefore, the driving force applied to the lens frame 102 can be increased relative to the torque input transmitted from the actuator 105 to the lead screw 106, and a lens driving device 100 with high driving efficiency can be realized.

[0042] Although the case where the lens frame 102 is driven in the direction G1 has been described here, the same applies to the case where the lens frame 102 is driven in the opposite direction G2.

[0043] For example, in a conventional configuration in which a power transmission member does not rotate, the lead screw diameter is 1.6 mm, the angle between the teeth of the power transmission member (rack, etc.) and the thread of the lead screw is 60°, the coefficient of sliding friction between the teeth and the thread is 0.1, and the force corresponding to F1 is 1 N. In this case, the load torque of the lead screw is 0.08 mmN.

[0044] In contrast to this, in this embodiment, D2 is 6 mm, D1 is 1 mm, the lead screw diameter is 1.6 mm, the angle between each tooth portion of the power transmission member 107 and the thread of the lead screw 106 is 60°, the sliding friction coefficient between the support shaft portion 102d and the connecting portion 107e is 0.1, and F1 is 1 N. In this case, the load torque of the lead screw 106 is 0.007 mmN. Thus, in this embodiment, the load torque of the lead screw 106 can be significantly reduced compared to the conventional configuration. EXAMPLES

[0045] Fig. 7(b) shows a lens driving device 200 according to the second embodiment. Fig. 7(a) shows a part of the lens driving device 200. Among the components of this embodiment, components common to or similar to those of the first embodiment are given the same names as those used in the first embodiment.

[0046] 7(b), the lens driving device 200 has a fixed member 201 having a hollow cylindrical shape, a lens frame 202 as a driven member disposed in the fixed member 201, and a main guide bar 203 and a sub guide bar 204 as guide means. The lens driving device 200 further has an actuator 205, a power transmission member 207, and an abutment member 208.

[0047] The lens frame 202 holds a lens (not shown). The main guide bar 203 and the sub guide bar 204 are fixed within the fixed member 201 by being held at both ends by fixing portions 201a and 201b provided on the inner surface of the fixed member 201.

[0048] The sleeve portion 202a of the lens frame 202 engages with the main guide bar 203 so as to be movable in the optical axis direction, and the rotation prevention portion 202b of the lens frame 202 engages with the sub guide bar 204 so as to be movable in the optical axis direction. The lens frame 202 is guided in the optical axis direction by the main guide bar 203 at the sleeve portion 202a. Furthermore, the rotation prevention portion 202b engages with the sub guide bar 204, thereby preventing the lens frame 202 from rotating around the main guide bar 203.

[0049] Actuator 205 is a rotational drive source such as a stepping motor, and is fixed to fixed member 201. A lead screw 206 is provided on the output shaft of actuator 205. The axial directions of lead screw 206, main guide bar 203, and sub guide bar 204 are parallel to the optical axis direction. A front end of lead screw 206 is rotatably held by a holding plate 209 fixed to actuator 205.

[0050] FIG. 8 shows a configuration for holding the power transmission member 207 in the lens frame 202. The power transmission member 207 is provided with first to fourth teeth portions, similar to the power transmission member 107 of the first embodiment. The diameter of each tooth portion is D2, the same as that of the first embodiment. A through hole 207g extending in the optical axis direction is formed in the center of the power transmission member 207, and a connecting shaft 210 is inserted into the through hole 207g and fixed integrally to the power transmission member 207. The diameter of the connecting shaft 210 is the same as the diameter D1 of the connecting portion 107e in the first embodiment. The connecting shaft 210 inserted into the through hole 207g may be fixed to the power transmission member 207 by any method that can fix the connecting shaft 210, such as press-fitting or bonding. The power transmission member 207 and the connecting shaft 210 fixed thereto can be collectively regarded as a power transmission member.

[0051] The lens frame 202 is provided with a holding recess 202f and a holding hole 202g for rotatably holding the rear end and front end of the connecting shaft 210, which serve as shaft portions protruding from the power transmission member 207, respectively.

[0052] This embodiment also satisfies the condition of formula (1) described in embodiment 1. It is also desirable to satisfy the condition of formula (6).

[0053] In the configuration of this embodiment, the power transmission member 207 (connecting shaft 210) is rotatably supported by the lens frame 202 on both sides thereof, and therefore the configuration is more rigid than that of the first embodiment, and a lens frame 202 with a larger mass can be driven. In this embodiment, when the diameter of the connecting shaft 210 is D4 and the diameter of the power transmission member 207 is D5, the resistance force acting between the lead screw 206 and the power transmission member 207 can be reduced in accordance with (D5 / D4). This makes it possible to reduce the loss when transmitting the driving force from the lead screw 206 to the power transmission member 207. Therefore, the driving force applied to the lens frame 202 can be increased relative to the torque input transmitted from the actuator 205 to the lead screw 206, and a lens driving device 200 with high driving efficiency can be realized.

[0054] In each of the above embodiments, a guide bar is used as a guide means for the driven member, but guide means other than a guide bar may be used. In addition, a configuration other than support by a support shaft portion or a connecting shaft as in each of the above embodiments may be used as a configuration for rotatably supporting the power transmission member. Furthermore, a configuration other than abutting against the abutting member shown in embodiment 1 (for example, biasing in a direction that blocks movement by a spring) may be used as a configuration for preventing linear movement of the power transmission member relative to the driven member. In addition, the shape of the meshing portion between the lead screw and the power transmission member may be a shape other than the shape described above.

[0055] In addition, in each of the above embodiments, the lens frame that holds the lens is described as the driven member, but the driven member may be something other than the lens frame. Furthermore, the same configuration as the lens driving device of each embodiment may be applied to various driving devices that drive various driven members other than lenses.

[0056] The above embodiment includes the following configurations.

[0057] (Configuration 1) A driven member that is movable in a linear direction; A lead screw that is rotationally driven by an actuator; a power transmission member that is supported by the driven member on an inner diameter side and engages with the lead screw on an outer diameter side, and transmits a driving force in the linear direction generated by rotation of the lead screw to the driven member, The drive device according to claim 1, wherein the power transmission member is supported so as to be rotatable together with the rotation of the lead screw. (Configuration 2) The drive device described in configuration 1, characterized in that the power transmission member is rotatably supported by the driven member so that the rotational resistance that the power transmission member receives from a portion rotatably supported by the driven member when the lead screw rotates is smaller than the rotational resistance that causes slippage at an engagement portion between the power transmission member and the lead screw. (Configuration 3) Let D1 be the diameter of a portion of the power transmission member that is rotatably supported by the driven member, and D2 be the diameter of a portion of the power transmission member that meshes with the lead screw. 1<(D2 / D1)<100 3. The driving device according to configuration 1 or 2, characterized in that the following conditions are satisfied. (Configuration 4) 4. The drive device according to any one of configurations 1 to 3, wherein the power transmission member has teeth on the outer diameter side that extend over the entire circumference in the rotational direction and mesh with the lead screw. (Configuration 5) 5. The drive device according to any one of configurations 1 to 4, wherein the power transmission member is rotatably supported by the driven member at a recess or a shaft portion provided on the inner diameter side. (Configuration 6) 6. The drive device according to any one of configurations 1 to 5, wherein the power transmission member is rotatably supported by the driven member on both sides in the linear direction. (Configuration 7) the power transmission member has a portion that abuts against the driven member in the linear direction, The drive device according to any one of configurations 1 to 6, wherein the contacting portion has a curved shape. (Configuration 8) A drive device according to any one of configurations 1 to 7; and an optical element holding member as the driven member for holding an optical element.

[0058] The embodiments described above are merely representative examples, and various modifications and alterations are possible for each embodiment when implementing the present invention. [Explanation of symbols]

[0059] 100,200 Lens drive unit 102,202 Lens frame 105,205 Actuator 106,206 Lead screw 107,207 Power transmission components

Claims

1. A moving member movable in a first direction; a shaft member extending in the first direction and rotated by an actuator; a transmission member including a tooth portion that meshes with the shaft member, The drive device, characterized in that the transmission member transmits a driving force in the first direction, which is generated by rotation of the shaft member, to the moving member on the inner diameter side of the tooth portion.

2. 2. The drive device according to claim 1, wherein the transmission member is rotatably supported by the moving member so that the rotational resistance that the transmission member receives from the portion rotatably supported by the moving member when the shaft member rotates is smaller than the rotational resistance that causes slippage at the meshing portion between the transmission member and the shaft member.

3. When the diameter of the portion of the transmission member that is rotatably supported relative to the moving member is D1, and the diameter of the portion of the transmission member that meshes with the shaft member is D2, 1<(D2 / D1)<100 2. The drive device according to claim 1, wherein the following conditions are satisfied:

4. 2. The drive device according to claim 1, wherein the transmission member moves in the first direction while rotating in accordance with the rotation of the shaft member.

5. 2. The drive device according to claim 1, wherein the transmission member is rotatably supported by the moving member at a recess or a shaft portion provided on the inner diameter side.

6. 2. The drive device according to claim 1, wherein the transmission member is rotatably supported by the moving member.

7. the transmission member has a portion that abuts against the moving member in the first direction, The drive device according to claim 1 , wherein the contacting portion has a curved surface.

8. A drive device according to any one of claims 1 to 7; an optical element holding member as the moving member for holding an optical element.

Images