Voice coil motor and lens barrel

Abstract

In order to provide a small voice coil motor, the voice coil motor includes a first yoke and a second yoke having lengths in a first direction, a third yoke having a length in the first direction and arranged between the first yoke and the second yoke, a first magnet arranged in the first yoke, a second magnet arranged in the second yoke, and a coil penetrated by the third yoke and capable of moving in the first direction by magnetic force of the first magnet and the second magnet, the coil having a first portion in which a winding wire is wound in a straight line shape and a second portion in which the winding wire is wound in a circular arc shape.

Description

Technical Field

[0001] This invention relates to voice coil motors and lens barrels. Background Technology

[0002] A lens barrel employing a voice coil motor as the lens drive mechanism has been proposed (e.g., Patent Document 1). The voice coil motor used within the lens barrel is expected to be miniaturized.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2015-49334 Summary of the Invention

[0006] According to the first embodiment, a voice coil motor includes: a first yoke and a second yoke having length in a first direction; a third yoke having length in the first direction and disposed between the first yoke and the second yoke; a first magnet disposed on the first yoke; a second magnet disposed on the second yoke; and a coil penetrated by the third yoke and movable in the first direction by the magnetic force of the first magnet and the second magnet. The coil has a first portion and a second portion, the first portion being a portion in which the winding wire is wound in a straight line, and the second portion being a portion in which the winding wire is wound in an arc shape.

[0007] According to the second method, the lens barrel is equipped with the aforementioned voice coil motor.

[0008] Furthermore, the structure of the embodiments described later can be appropriately modified, or at least a portion can be replaced with other structures. Moreover, structural elements whose configuration is not particularly limited are not limited to the configuration disclosed in the embodiments and can be configured in positions that enable their function. Attached Figure Description

[0009] Figure 1 This is a diagram showing a camera having a lens barrel and a camera body according to one embodiment.

[0010] Figure 2 (A) is a perspective view showing the structure of a voice coil motor. Figure 2 (B) is from Figure 2 Observe the diagram of the voice coil motor in the direction of arrow AR1 in (A).

[0011] Figure 3 (A) is Figure 1 AA-line sectional view, Figure 3 (B) is a magnified view of a portion of the coil.

[0012] Figure 4 (A) is a cross-sectional view of the voice coil motor involved in Comparative Example 1. Figure 4 (B) is a cross-sectional view of a voice coil motor. Figure 4 (C) is a cross-sectional view of the voice coil motor involved in Comparative Example 2.

[0013] Figure 5 (A) is a three-dimensional view of the first side yoke, the second side yoke, and the lower yoke. Figure 5 (B) is a schematic front view of a voice coil motor. Figure 5 (C) is a side view of the central magnetic yoke. Figure 5 (D) is a diagram of the voice coil motor with the upper yoke removed, viewed from the upper yoke side. Figure 5 (E) is a three-dimensional diagram of the upper magnetic yoke.

[0014] Figure 6 This is a diagram used to illustrate the driving force of the coil in the voice coil motor involved in Comparative Example 3.

[0015] Figure 7 (A) and Figure 7 Figure (B) is a diagram showing other examples of lower and upper yokes. Figure 7 (C) is a diagram illustrating the assembly of the voice coil motor. Detailed Implementation

[0016] Hereinafter, with reference to the accompanying drawings, a lens barrel 100 according to one embodiment will be described in detail. Furthermore, in the various figures, for ease of understanding, illustrations of certain elements are sometimes omitted.

[0017] Figure 1 This diagram shows a camera 1 equipped with the lens barrel 100 and camera body 101 according to this embodiment. Furthermore, in this embodiment, the lens barrel 100 can be attached to and detached from the camera body 101, but this is not a limitation; the lens barrel 100 and the camera body 101 may also be integral.

[0018] The camera body 101 internally includes an imaging element 111 and a control unit 112. The imaging element 111 is composed of photoelectric conversion elements such as CCD (Charge Coupled Device), which converts the image of the subject obtained by the imaging optical system (the lens barrel 100 mounted on the camera body 101) into an electrical signal.

[0019] The control unit 112 includes a CPU (Central Processing Unit) and other components, and centrally controls the overall operation of the camera 1, including the camera body 101 and the lens barrel 100 on which it is mounted, which is involved in the focus drive for shooting.

[0020] like Figure 1 As shown, the lens barrel 100 according to this embodiment includes a first fixing barrel 10 and a second fixing barrel 20 disposed on the inner peripheral side relative to the first fixing barrel 10. In this embodiment, the first fixing barrel 10 is composed of multiple components, but it may also be composed of a single component. Figure 1 As shown, a lens holder LM is fixed at the first fixed cylinder 10, which allows the lens barrel 100 to be attached to or detached from the camera body 101.

[0021] In addition, the lens barrel 100 has a plurality of lenses L1 to L4 arranged sequentially along a common optical axis OA. Lens L3 is held in the lens holding frame F3, and the other lenses are held in the second fixing barrel 20. Lenses L1 to L4 may also be composed of multiple lenses.

[0022] In this embodiment, lens L3 is a focusing lens that moves along the optical axis to adjust the focus. Lens L3 is configured to move along the optical axis via a voice coil motor (VCM) 30 disposed inside the lens barrel 100.

[0023] The lens holding frame F3 has a locking portion 116 protruding in a direction intersecting the optical axis OA. The locking portion 116 engages with a straight groove 22 provided by the second fixing cylinder 20. The straight groove 22 extends in the optical axis direction, thereby restricting the rotation of the lens holding frame F3 centered on the optical axis OA. The lens holding frame F3 is guided by the straight groove 22 and moves linearly in the optical axis direction. Alternatively, the lens holding frame F3 can be guided in the optical axis direction by a guide rod extending in the optical axis direction instead of the straight groove 22.

[0024] The VCM30 is driven by the drive unit 113. Under the control of the control unit 112 of the camera body 101, the drive unit 113 controls the focusing drive of the lens L3. Specifically, the drive unit 113 generates a drive signal for the VCM30 based on the position information of the lens L3 input from a position detection mechanism (not shown) such as an optical encoder or magnetic encoder and the target position information of the lens L3 input from the control unit 112 of the camera body 101, and outputs it to the VCM30.

[0025] The VCM30 drives lens L3 linearly along the optical axis using a drive signal. Details will be described later, but... Figure 1As shown, the lens holding frame F3 is connected to the coil 35 provided in the VCM30. Specifically, the lens holding frame F3 is connected to the coil 35 via the connecting part 115 of the lens holding frame F3, by means of, for example, an adhesive. Therefore, if the coil 35 is driven linearly in the optical axis direction, the lens holding frame F3 is driven linearly in the optical axis direction, and the position of the lens L3 in the optical axis direction changes.

[0026] Furthermore, when the drive signal of VCM30 is OFF, the coil 35 of VCM30 moves freely because it lacks the holding force to maintain its position. Therefore, when the lens barrel 100 is facing upwards or downwards, the coil 35 moves due to the weight of the lens holding frame F3 and the lens L3, posing a risk that the lens holding frame F3 may collide with the second fixed cylinder 20, producing an impact sound. Therefore, as... Figure 1 As shown, in the optical axis direction, a cushioning material 40 is provided on the portion of the second fixed cylinder 20 that overlaps with the lens holding frame F3. Therefore, when the lens holding frame F3 collides with the cushioning material 40, the impact is mitigated and the impact sound is suppressed.

[0027] Regarding the camera 1, which consists of a camera body 101 and a lens barrel 100 as described above, if a shutter button (not shown) is pressed (released or focused), the control unit 112 in the camera body 101 controls the focusing drive of the lens barrel 100 via the drive device 113. Furthermore, the imaging element 111 converts the subject image light obtained by imaging the lens barrel 100 into an electrical signal and records (i.e., captures) the image data in a memory (not shown) provided in the camera body 101.

[0028] Next, the structure of VCM30 for driving lens L3 will be explained. Figure 2 (A) is a perspective view showing the structure of VCM30. Figure 2 (B) is from Figure 2 Observe the VCM30 diagram in the direction of arrow AR1 in (A). Figure 3 (A) is Figure 1 AA-line sectional view, Figure 3 (B) is a partial enlarged view of coil 35.

[0029] like Figure 2 (A) and Figure 2 As shown in (B), the VCM30 of this embodiment includes: a first side yoke 31a and a second side yoke 31b, which have lengths in the optical axis direction; and a central yoke 32, which has lengths in the optical axis direction and is disposed between the first side yoke 31a and the second side yoke 31b.

[0030] In addition, VCM30 includes: an upper yoke 34a, which connects one end of the first side yoke 31a, the second side yoke 31b, and the central yoke 32 in the optical axis direction; and a lower yoke 34b, which connects the other end of the first side yoke 31a, the second side yoke 31b, and the central yoke 32 in the optical axis direction. Thus, a closed magnetic circuit is formed.

[0031] The first magnet 33a is disposed on the side of the central yoke 32 of the first yoke 31a, and the second magnet 33b is disposed on the side of the central yoke 32 of the second yoke 31b.

[0032] The first magnet 33a is configured, for example, with the N pole on the side of the central yoke 32, and the second magnet 33b is also configured with the N pole on the side of the central yoke 32. This forms a magnetic circuit in which magnetic flux enters the central yoke 32 from the N poles of the first magnet 33a and the second magnet 33b, passes through the upper yoke 34a and the lower yoke 34b, and returns to the S poles of the first magnet 33a and the second magnet 33b, respectively.

[0033] Additionally, the VCM30 has a coil 35 that is penetrated by the central yoke 32. For example... Figure 3 As shown in (A), the coil 35 of the VCM30 in this embodiment has a generally D-shaped form. Specifically, the coil 35 has a straight portion 351 formed by winding the winding wire in a straight line, a curved portion 352 formed by winding the winding wire in an arc shape, and a connecting portion 353 connecting the straight portion 351 and the curved portion 352. The curved portion 352 is positioned opposite the straight portion 351, sandwiching the central yoke 32. Furthermore, the direction of the current flowing through the straight portion 351 is either from the first yoke 31a to the second yoke 31b or from the second yoke 31b to the first yoke 31a.

[0034] Plane P1 intersects with plane P2. Plane P1 includes the side surface S1 of the first side yoke 31a opposite to the first magnet 33a, and plane P2 includes the side surface S2 of the second side yoke 31b opposite to the second magnet 33b. Furthermore, the central yoke 32 is located between the intersection line IL1 of planes P1 and P2 and the straight portion 351 of the coil 35. That is, the straight portion 351 of the coil 35 is positioned on the side of the first fixed cylinder 10 (outer peripheral side). By having the coil 35 have a straight portion 351 and positioning it on the outer peripheral side, the VCM 30 can be miniaturized. Additionally, sufficient driving force can be ensured. This will be explained in detail.

[0035] Figure 4 (A) is a cross-sectional view of the VCM300A involved in Comparative Example 1. Figure 4 (B) is a sectional view of VCM30. Figure 4(C) is a cross-sectional view of the VCM300B involved in Comparative Example 2. Figure 4 (A) Figure 4 (C) is equivalent to Figure 1 A sectional view along line AA. In Figure 4 (A) Figure 4 In (C), the inner circumferential surface of the first fixed cylinder 10 is represented by a dashed line L22, and the outer circumference of the lens holding frame F3 is represented by a dashed line L21.

[0036] like Figure 4 As shown in (A), the coil 350A of the VCM300A involved in Comparative Example 1 does not have a straight portion formed by winding the winding wires in a straight line, but is cylindrical. The number of layers of winding wires of coil 350A (the radial thickness of coil 350A) is the same as the number of layers of winding wires of coil 35 involved in the embodiment. In addition, the central yoke 320A involved in Comparative Example 1 is cylindrical, and its diameter is equal to that of an imaginary cylinder CL1 whose outer peripheral surface coincides with a portion of the outer peripheral surface of the central yoke 32 of VCM30. Figure 4 The diameter D1 is shown by the dashed line in (B). The dimensions and configuration of the first side yoke 31a and the second side yoke 31b, the upper yoke 34a and the lower yoke 34b, and the first magnet 33a and the second magnet 33b are the same as those of VCM30.

[0037] In Comparative Example 1, since coil 350A does not have a straight portion, a portion of coil 350A protrudes further outward than the first side yoke 31a, the second side yoke 31b, the upper yoke 34a, and the lower yoke 34b. As a result, the radial dimension of VCM300A of lens L3 is larger than that of VCM30. Therefore, when using VCM300A, the inner diameter of the first fixing cylinder 10 is larger than when using VCM30, resulting in a larger lens barrel size.

[0038] On the other hand, in the VCM30 involved in this embodiment, such as Figure 4 As shown in (B), the coil 35 has a straight portion 351, so the coil 35 does not protrude further outward compared to the first side yoke 31a, the second side yoke 31b, the upper yoke 34a, and the lower yoke 34b. Therefore, the radial dimension of the lens VCM30 is reduced. This allows for a smaller inner diameter of the first fixing tube 10, thus enabling miniaturization of the lens barrel 100.

[0039] exist Figure 4In the VCM300B of Comparative Example 2 shown in (C), the diameter and position of the central yoke 320B are adjusted so that the cylindrical coil 350B on the outer periphery does not protrude from the first yoke 31a, the second yoke 31b, the upper yoke 34a, and the lower yoke 34b. In the VCM300B, the number of winding wire layers of the coil 350B (the radial thickness of the coil 350B) is the same as the number of winding wire layers of the coil 35 according to the embodiment. In the VCM300B of Comparative Example 2, the radial dimension of the VCM300B can be reduced, but the diameter of the central yoke 320B becomes smaller. As a result, if the dimensions and configuration of the first side yoke 31a and the second side yoke 31b, the upper yoke 34a and the lower yoke 34b, and the first magnet 33a and the second magnet 33b are made the same as those of VCM 30, then the distances between the first side yoke 31a and the first magnet 33a and the central yoke 320B, as well as the distances between the second side yoke 31b and the second magnet 33b and the central yoke 320B, become longer, risking insufficient driving force. More specifically, in the direction from the first magnet 33a to the central yoke 320B, the magnitude of the magnetic force of the first magnet 33a near the central yoke 320B is inversely proportional to the square of the distance between the first magnet 33a and the central yoke 320B, according to Coulomb's law. Similarly, in the direction from the second magnet 33b to the central yoke 320B, the magnitude of the magnetic force of the second magnet 33b near the central yoke 320B is inversely proportional to the square of the distance between the second side yoke 31b and the distance between the second magnet 33b and the central yoke 320B, according to Coulomb's law. Therefore, the longer the distance between the first magnet 33a and the central yoke 320B, and the longer the distance between the second magnet 33b and the central yoke 320B, the smaller the magnetic force applied to the coil 35, and the smaller the driving force of the coil 35. Furthermore, even if the first side yoke 31a and the second side yoke 31b, as well as the first magnet 33a and the second magnet 33b, are arranged close to the central yoke 320B, the magnetic flux is difficult to flow within the central yoke 320B due to its small diameter, and there is a risk of insufficient driving force.

[0040] On the other hand, in the VCM30 involved in this embodiment, such as Figure 4As shown in (B), the diameter of the central yoke 32 can be increased. For example, the diameter D1 of the imaginary cylinder CL1, whose outer circumferential surface coincides with a portion of the outer circumferential surface of the central yoke 32, can be greater than the length L11 of the rectangular shape in the case of the first side yoke 31a and the second side yoke 31b when viewed from the optical axis. Therefore, magnetic flux can flow more easily through the central yoke 32. In addition, the distances between the first side yoke 31a and the first magnet 33a and the central yoke 32, as well as the distances between the second side yoke 31b and the second magnet 33b and the central yoke 320B, can be shortened, thus increasing the driving force of the VMC 30.

[0041] In this way, the coil 35 has a straight section 351, which enables the miniaturization of the VCM 30 and the lens barrel 100. In addition, the VCM 30 can ensure sufficient driving force.

[0042] Return to Figure 3 In (B), coil 35 is a multi-layered wound coil, and the intersection point CP (the portion where the winding lines 355 of layer n+1 cross over the winding lines 355 of layer n) where the winding lines 355 of coil 355 intersect each other is located in the straight section 351. At the intersection point CP, coil 35 bulges slightly (the radial thickness of coil 35 increases), so if the intersection point CP is located in the curved section 352 that engages with lens holding frame F3, there is a risk that the lens holding frame F3 and coil 35 cannot be accurately positioned. More specifically, if the portion where the intersection point CP is located is set as the curved section 352 of coil 35, and the curved section 352 is engaged with lens holding frame F3, there is a risk that coil 35 will engage with lens holding frame F3 at an angle, making it impossible to achieve the desired positioning. In this embodiment, by placing the intersection point CP in the straight section 351 that is not used for positioning coil 35 and lens holding frame F3, it is possible to accurately engage coil 35 and lens holding frame F3 at a specified position.

[0043] From the drive device 113 (see reference) disposed within the lens barrel 100 Figure 1 A drive signal (current) is input to coil 35. If current flows through coil 35, coil 35 moves along the optical axis due to the magnetic force of the first magnet 33a and the second magnet 33b. More specifically, coil 35 moves along the optical axis through the electromagnetic interaction between the current flowing through coil 35 and the first magnet 33a and the second magnet 33b. By changing the direction of the current flowing through coil 35, the direction of movement of coil 35 can be switched between the subject side and the camera body 101 side. Furthermore, by changing the value of the current flowing through coil 35, the driving force and moving speed of coil 35 can be changed.

[0044] A more detailed description of the components of the VCM30. Figure 5(A) is a three-dimensional view of the first side yoke 31a, the second side yoke 31b, and the lower yoke 34b. Figure 5 (B) is a schematic front view of the VCM30. Figure 5 (C) is a side view of the central magnetic yoke 32. Figure 5 (D) is a diagram of VCM30 with the upper yoke 34a removed, viewed from the side of the upper yoke 34a. Figure 5 (E) is a three-dimensional view of the upper magnetic yoke 34a.

[0045] like Figure 5 As shown in (A), the first side yoke 31a, the second side yoke 31b, and the lower yoke 34b are integrally formed from a single component. The first side yoke 31a, the second side yoke 31b, and the lower yoke 34b can be integrally formed, for example, by bending a flat sheet of cold-rolled steel plate (SPCC: Steel Plate Cold Commercial) obtained by stamping and cutting to specified dimensions.

[0046] The first magnet 33a and the second magnet 33b used in the VCM30 have strong magnetic forces. Therefore, when the first side yoke 31a, the second side yoke 31b, and the lower yoke 34b are formed by different components, during the assembly of the VCM30, the first side yoke 31a and the second side yoke 31b, on which the first magnet 33a and the second magnet 33b are mounted, will magnetically attract other components (upper yoke 34a, lower yoke 34b, and central yoke 32), which may make assembly difficult. Alternatively, special clamps may be needed to prevent the positions of the components from shifting due to magnetic forces.

[0047] On the other hand, in this embodiment, the first side yoke 31a, the second side yoke 31b, and the lower yoke 34b are integrally formed from a single component. Therefore, even after the first magnet 33a and the second magnet 33b are installed onto the first side yoke 31a and the second side yoke 31b, the first side yoke 31a, the second side yoke 31b, and the lower yoke 34b can maintain their position and orientation. Thus, the installation of the central yoke 32, the coil 35, and the upper yoke 34a becomes easier. That is, the assembly of the VCM 30 becomes easier.

[0048] When the first side yoke 31a, the second side yoke 31b, and the lower yoke 34b are integrally formed from a single component, such as Figure 5 As shown in (B), the connection between the lower yoke 34b and the first yoke 31a, and the connection between the lower yoke 34b and the second yoke 31b, become curved, making it difficult for magnetic flux to flow. On the other hand, the connection between the first yoke 31a and the upper yoke 34a, and the connection between the second yoke 31b and the upper yoke 34a, allows for easier magnetic flux flow compared to the lower yoke 34b.

[0049] Figure 6 This diagram illustrates the driving force of coil 35 in the VCM300C involved in Comparative Example 3. In the VCM300C, the first magnet 33a and the second magnet 33b are positioned such that the distance d2 between the first magnet 33a and the second magnet 33b and the upper yoke 34a is equal to the distance d1 between the first magnet 33a and the second magnet 33b and the lower yoke 34b. Other structures are the same as in the VCM30. Figure 6 In the diagram, on the right side of VCM300C, a coordinate graph showing the driving force of coil 35 at the position it has moved to is displayed. In this graph, the position where the center of the extension direction of coil 35 coincides with the center of the extension direction of the central yoke 32 is set to 0, showing the driving force of coil 35 at the position it has moved to when the center of coil 35 moves upwards towards the yoke 34a or downwards towards the yoke 34b. If... Figure 6 As shown, if the distance d2 between the first magnet 33a and the second magnet 33b and the upper yoke 34a and the distance d1 between the first magnet 33a and the lower yoke 34b are equal, then the driving force on the lower yoke 34b side is lower than the driving force on the upper yoke 34a side.

[0050] Therefore, in this embodiment, in order to make the driving force uniform in the optical axis direction, the first magnet 33a and the second magnet 33b are arranged closer to the lower magnet 34b than the upper magnet 34a. More specifically, as... Figure 5 As shown in (B), the first magnet 33a and the second magnet 33b are arranged such that the distance d1 between the first magnet 33a and the second magnet 33b and the lower yoke 34b is shorter than the distance d2 between the first magnet 33a and the second magnet 33b and the upper yoke 34a. This allows the driving force of the VCM30 to be uniform along the optical axis, enabling stable driving of the lens L3.

[0051] Next, the structure of the central magnetic yoke 32 will be described. The material of the central magnetic yoke 32 is, for example, SS (Steel Structure) 400.

[0052] like Figure 5 As shown in (D), the surface of the central yoke 32, which is opposite to the straight portion 351 of the coil 35, is approximately parallel to the straight portion 351. More specifically, the surface of the central yoke 32, which is opposite to the straight portion 351 of the coil 35, is approximately parallel to the surface of the central yoke 32 side of the straight portion 351. As a result, the approximately D-shaped coil 35 can move smoothly in the direction of the optical axis.

[0053] In addition, such as Figure 5As shown in (C), the central yoke 32 has protrusions 321a and 321b on both end faces in the optical axis direction for positioning the central yoke 32. Specifically, the protrusions 321a and 321b engage with engagement portions 341a and 341b formed on the upper yoke 34a and lower yoke 34b respectively (see Figure 1). Figure 5 (A) and Figure 5 The (E) engages with the convex portions 321a and 321b to position the central yoke 32. In this embodiment, the engaging portions 341a and 341b are through holes passing through the upper yoke 34a and the lower yoke 34b, and engage with the protrusions 321a and 321b. Therefore, by inserting the protrusions 321a and 321b into these through holes (engaging portions 341a and 341b), the central yoke 32 is positioned. Alternatively, the engaging portions 341a and 341b may not pass through the upper yoke 34a and the lower yoke 34b.

[0054] As detailed above, the VCM30 of this embodiment includes: a first side yoke 31a and a second side yoke 31b, having length in the optical axis direction; a central yoke 32, having length in the optical axis direction, and disposed between the first side yoke 31a and the second side yoke 31b; a first magnet 33a disposed on the first side yoke 31a; a second magnet 33b disposed on the second side yoke 31b; and a coil 35, which is penetrated by the central yoke 32 and can move in the optical axis direction by the magnetic force of the first magnet 33a and the second magnet 33b. The coil 35 has a straight portion 351 formed by winding the winding wire in a straight line.

[0055] As described above, the coil 35 has a straight portion 351, which allows for miniaturization of the VCM 30. Furthermore, compared to a VCM with a coil that does not have a straight portion 351, the driving force of the VCM 30 can be increased.

[0056] Furthermore, according to this embodiment, the coil 35 has a curved portion 352 formed by winding the winding wire in an arc shape. As a result, the curved portion 352 protrudes further inward than the upper yoke 34a and the lower yoke 34b, making it easier to attach the lens holding frame F3 to the coil 35.

[0057] Furthermore, in this embodiment, the surface of the central yoke 32 opposite to the straight portion 351 of the coil 35 is approximately parallel to the straight portion 351. Therefore, the coil 35 having the straight portion 351 can move smoothly along the central yoke 32.

[0058] Furthermore, in this embodiment, the first side yoke 31a and the second side yoke 31b have a rectangular shape when viewed from the optical axis direction, and the diameter D1 of the imaginary cylinder CL1, whose outer peripheral surface coincides with a portion of the outer peripheral surface of the central yoke 32, is greater than the length L11 of the rectangular shape in the longitudinal direction. This shortens the distance between the first magnet 33a and the second magnet 33b and the central yoke 32, thus increasing the driving force of the VCM 30.

[0059] Furthermore, in this embodiment, the intersection point CP where the winding lines of coil 35 intersect each other is located at the straight section 351. At the intersection point CP, coil 35 bulges outward radially. By positioning the intersection point CP at the straight section 351, compared to the case where the intersection point CP is located at the curved section 352 that engages with the lens holding frame F3, coil 35 can be accurately positioned at a designated location. Additionally, the portion where the intersection point CP is located does not contact the first magnet 33a and the second magnet 33b, thus allowing coil 35 to move smoothly.

[0060] In this embodiment, the VCM30 includes: an upper yoke 34a, which connects one end of the first side yoke 31a, the second side yoke 31b, and the central yoke 32 along the optical axis; and a lower yoke 34b, which connects the other end of the first side yoke 31a, the second side yoke 31b, and the central yoke 32 along the optical axis. The first side yoke 31a, the second side yoke 31b, and the lower yoke 34b are integrally formed by a single component. In the optical axis direction, the distance d1 between the upper yoke 34a and the first magnet 33a and the second magnet 33b is shorter than the distance d2 between the lower yoke 34b and the first magnet 33a and the second magnet 33b. Therefore, the ease of magnetic flux flow at the connection between the first side yoke 31a and the second side yoke 31b and the lower yoke 34b, as well as the ease of magnetic flux flow at the connection between the first side yoke 31a and the second side yoke 31b and the upper yoke 34a, can be set to the same level, so that the driving force of VCM30 can be made uniform in the optical axis direction.

[0061] Furthermore, in this embodiment, the central magnetic yoke 32 has protrusions 321a and 321b on both end faces in the optical axis direction, and the upper magnetic yoke 34a and lower magnetic yoke 34b have engaging portions 341a and 341b that engage with the protrusions 321a and 321b, respectively. This allows for the positioning of the central magnetic yoke 32.

[0062] Furthermore, in the above embodiment, the winding wire is wound in a curved shape at the connection portion 353, but it can also be wound in a straight shape.

[0063] Furthermore, in the above embodiment, the material of the central yoke 32 is different from the materials of the first side yoke 31a and the second side yoke 31b, but it can be the same as or different from the materials of the first side yoke 31a and the second side yoke 31b. However, the material of the central yoke 32 is preferably a material having a higher saturation magnetic flux density than the materials of the first side yoke 31a and the second side yoke 31b. This improves the flow of magnetic flux in the central yoke 32 and increases the driving force of the VCM 30.

[0064] Furthermore, in the above embodiments, such as Figure 7 (A) and Figure 7 As shown in (B), the engaging portions 341a and 341b of the upper yoke 34a and the lower yoke 34b can also open toward the lens L3. Thus, for example, as... Figure 7 As shown in (C), after the first magnet 33a, the second magnet 33b, and the upper yoke 34a are mounted onto the integrally formed first side yoke 31a, second side yoke 31b, and lower yoke 34b, the protrusions 321a and 321b of the central yoke 32 through the coil 35 are inserted (slid) into the engaging portions 341a and 341b from their opening sides, thereby positioning the central yoke 32 between the first side yoke 31a and the second side yoke 31b. Furthermore, after positioning the central yoke 32 between the first side yoke 31a and the second side yoke 31b, the protrusions 321a and 321b of the central yoke 32 are respectively engaged with the upper yoke 34a and the lower yoke 34b, thereby positioning the central yoke 32. Therefore, the assembly of the VCM becomes easy. In addition, the engaging parts 341a and 341b may not face the lens L3 but face the opening of the first fixing cylinder 10.

[0065] Furthermore, in the above embodiments, the second fixed cylinder 20 that houses the lens holding frame F3 can also be a movable cylinder capable of linear movement in the optical axis direction. Additionally, in the above embodiments and their variations, the lens barrel 100 can be either a fixed-focus lens or a zoom lens. Furthermore, the VCM 30 can also be used in a location other than the lens barrel.

[0066] The above-described embodiments are suitable examples. However, they are not limited thereto, and various modifications can be made to implement them without departing from the spirit of the subject, and arbitrary combinations of structural elements are also possible.

[0067] Label Explanation

[0068] 1 camera

[0069] 30 voice coil motor

[0070] 31a First side magnetic yoke

[0071] 31b Second side magnetic yoke

[0072] 32-center magnetic yoke

[0073] 33a First Magnet

[0074] 33b Second Magnet

[0075] 34a upper magnetic yoke

[0076] 34b lower magnetic yoke

[0077] 35 coil

[0078] 100mm lens barrel

[0079] 101 camera body

[0080] 351 Straight Section

[0081] 352 Curve Section

[0082] 355 winding wire

[0083] L3 lens

[0084] F3 Lens Holding Frame

Claims

1. A voice coil motor, comprising: The first and second magnetic yokes have length in the first direction; A third magnetic yoke, having a length in the first direction, is disposed between the first magnetic yoke and the second magnetic yoke; The first magnet is disposed on the first magnetic yoke; A second magnet, disposed on the second magnetic yoke; and The coil, penetrated by the third magnetic yoke, is movable in the first direction by the magnetic forces of the first and second magnets. The coil has a first part and a second part, the first part being formed by winding the winding wire in a straight line, and the second part being formed by winding the winding wire in an arc shape. The first and second magnetic yokes have a rectangular shape when viewed from the first direction. The diameter of the imaginary cylinder is greater than the length of the rectangular shape in the longitudinal direction, and the outer circumferential surface of the imaginary cylinder coincides with a portion of the outer circumferential surface of the third magnetic yoke.

2. The voice coil motor according to claim 1, wherein, The second part sandwiches the third magnetic yoke and is opposite to the first part.

3. The voice coil motor according to claim 1 or 2, wherein, The coil has a generally D-shaped form when viewed from the first direction.

4. The voice coil motor according to claim 1 or 2, wherein, The face of the third yoke opposite the first part is substantially parallel to the first part.

5. The voice coil motor according to claim 1 or 2, wherein, The intersection point where the windings of the coil intersect each other is located in the first part.

6. The voice coil motor according to claim 1 or 2, wherein, A first plane intersects with a second plane, the first plane including a first side of the first yoke opposite the first magnet, and the second plane including a second side of the second yoke opposite the second magnet. The third magnetic yoke is located between the intersection of the first plane and the second plane and the first portion of the coil.

7. The voice coil motor according to claim 1 or 2, wherein, The voice coil motor has the following features: A fourth magnetic yoke connects one end of the first magnetic yoke, the second magnetic yoke, and the third magnetic yoke in the first direction; and The fifth magnetic yoke connects the other ends of the first, second, and third magnetic yokes in the first direction. The first magnetic yoke, the second magnetic yoke, and the fifth magnetic yoke are integrally formed by a single component.

8. The voice coil motor according to claim 7, wherein, In the first direction, the distance between the fourth magnetic yoke and the first and second magnets is shorter than the distance between the fifth magnetic yoke and the first and second magnets.

9. The voice coil motor according to claim 7, wherein, The third magnetic yoke has protrusions on both end faces in the first direction. The fourth and fifth magnetic yokes each have an engaging portion that engages with the protrusion.

10. A lens barrel comprising a voice coil motor as described in any one of claims 1 to 9.

11. The lens barrel according to claim 10, wherein, The lens barrel includes: Lenses; and A lens holding frame holds the lens and is connected to the coil. The voice coil motor is configured such that the first direction is parallel to the optical axis of the lens. In the radial direction of the lens, the third magnetic yoke is located between the first portion of the coil and the lens.

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