Lens driving unit

Abstract

A lens drive unit (1) is provided with: a lens holding unit (2) that holds at least one lens (R); a support shaft (3) that supports the lens holder (2) so as to be movable in a first direction (D1), which is the direction in which the optical axis (C) of the lens (R) extends; an actuator (4) having a drive shaft (41) extending in the first direction (D1) and vibrating in the first direction (D1); and a base (51) to which the support shaft (3) and the actuator (4) are fixed, in which the lens holding section (2) has a first engagement section (21) having a pair of friction surfaces (211) that sandwich the drive shaft (41), so that it is possible to prevent a load from being applied to the actuator (4).

Description

Lens drive unit Technical Field

[0001] The present invention relates to a lens driving unit for driving a lens in an optical axis direction. Background Art

[0002] Conventionally, there is known a lens driving unit that includes a small actuator using a piezoelectric element that expands and contracts in a predetermined direction and drives a lens in the optical axis direction (see Japanese Patent Application Laid-Open No. 2015-105988).

[0003] As shown in FIG. 8 and FIG. 9 , the lens driving unit 100 includes a device body 101 , an actuator 104 held by the device body 101 , and a moving member 105 driven by the actuator 104 .

[0004] The device body 101 includes a holding member 102 and a cover 103. The holding member 102 includes an actuator holding portion 121 at a first corner portion 102a for holding the actuator 104. A third support column 120c is provided at a third corner portion 102c, located diagonally opposite the first corner portion 102a. The third support column 120c includes a restrictor receiving groove 122 into which a portion (rotation restrictor) 161 of the movable member 105 is vertically movably inserted.

[0005] The actuator 104 includes a piezoelectric element 141 that expands and contracts in a predetermined direction, and a driving shaft 142 that is joined to one end of the piezoelectric element 141 .

[0006] The moving member 105 includes a substantially cylindrical moving member body 106 and an engaging member 107 that engages with the drive shaft 142 with a predetermined friction force.

[0007] The moving member body 106 holds at least one lens on its inner periphery and has a rotation restricting portion 161 on its outer periphery. The rotation restricting portion 161 protrudes in the radial direction of the lens and restricts the rotation of the moving member 105 relative to the drive shaft 142 .

[0008] The engaging member 107 includes a metal, elastic, belt-shaped engaging member main body 171 and a metal, elastic, belt-shaped elastic body 173 .

[0009] The engagement member body 171 includes a drive bearing portion 172 at one end in the longitudinal direction. The drive bearing portion 172 includes a first receiving portion 172 a and a second receiving portion 172 b extending substantially perpendicularly from the first receiving portion 172 a .

[0010] The elastic body 173 has a pressing portion 173a at one end in the longitudinal direction, and this pressing portion 173a presses the drive shaft 142 against the drive bearing portion 172. Furthermore, the drive shaft 142 is sandwiched between the drive bearing portion 172 and the pressing portion 173a of the engaging member 107 connected to the movable member main body 106. As a result, the engaging member 107 is slidably engaged with the drive shaft 142 in the axial direction.

[0011] In the lens driving unit 100 constructed as described above, when power is supplied to the piezoelectric element 141 from a driving circuit provided on a mobile terminal, etc., the piezoelectric element 141 vibrates axially and the driving shaft 142 moves back and forth through its vibration (extension), and the moving part 105 moves toward the axial direction (optical axis direction) of the driving shaft 142 through its reciprocating movement.

[0012] However, since the movable component 105 in the lens driving unit 100, which maintains at least one lens, is a structure that moves back and forth along the axial direction (optical axis direction) of the driving shaft 142 while being supported only by the actuator 104, that is, the weight of the lens and the movable component 105 is entirely applied to the actuator 104, the actuator 104 may be damaged when a mobile phone equipped with the lens driving unit 100 is impacted.

[0013] Prior art literature

[0014] Patent Document 1

[0015] Japanese Patent Application Laid-Open No. 2015-105988.

[0016] Summary of the Invention

[0017] Problems to be solved by the invention

[0018] Therefore, an object of the present invention is to provide a lens driving unit in which a load is less likely to be applied to an actuator.

[0019] Solutions for solving problems

[0020] The lens driving unit according to the present invention has:

[0021] a lens holding portion that holds at least one lens;

[0022] a support shaft that supports the lens holding portion so as to be movable in a first direction, that is, an optical axis direction of the lens;

[0023] an actuator having a drive shaft extending in a first direction and vibrating in the first direction; and

[0024] a base to which the support shaft and the actuator are fixed,

[0025] The lens holding portion includes a first engaging portion having a pair of friction surfaces that sandwich the drive shaft.

[0026] In the lens driving unit,

[0027] The actuator includes a piezoelectric element connected to one end of the drive shaft and configured to reciprocate the drive shaft in the first direction by expanding and contracting in the first direction.

[0028] In addition, in the lens driving unit,

[0029] The support shaft may also support the lens holding portion by magnetic force so as to be movable in the first direction.

[0030] In addition, in the lens driving unit,

[0031] The support shaft extends in the first direction and is formed of a magnet,

[0032] The lens holding portion may further include a second engaging portion engaged with the support shaft.

[0033] The second engaging portion may further include:

[0034] an insertion hole, which passes through along the first direction and through which the support shaft is inserted; and

[0035] The magnet is arranged at a position pressing the inner peripheral surface of the insertion hole against the support shaft along a second direction perpendicular to the first direction.

[0036] In addition, in the lens driving unit,

[0037] The lens holding portion includes a holding portion body surrounding the at least one lens.

[0038] The first engaging portion and the second engaging portion may be further arranged on both sides of the holding portion body in a radial direction of the lens when viewed from the first direction.

[0039] In addition, in the lens driving unit,

[0040] The pair of friction surfaces may further extend along a plane direction orthogonal to a third direction and clamp the drive shaft in the third direction. The third direction is orthogonal to the first direction and the second direction.

[0041] In addition, in the lens driving unit,

[0042] The lens holding portion includes:

[0043] a holding portion body surrounding the at least one lens; and

[0044] a plurality of extensions, each of which is spaced apart in the first direction and extends from the holding portion body;

[0045] The plurality of extensions may further include the insertion holes at positions where the extensions overlap when viewed from the first direction.

[0046] In addition, in the lens driving unit,

[0047] The lens holding portion includes:

[0048] a holding portion body surrounding the at least one lens; and

[0049] a pair of extensions spaced apart in the first direction and extending from the holding portion body;

[0050] The pair of extensions are included in the second engaging portion and are movable in the first direction relative to the support shaft and are engaged with the support shaft.

[0051] The center of gravity of the lens holding portion in a state of holding the at least one lens may be located between the pair of extension portions in the first direction.

[0052] In addition, the lens driving unit,

[0053] A cover member that forms a housing together with the base may be further provided.

[0054] In addition, in the lens driving unit,

[0055] In the support shaft, the portion engaging with the second engaging portion on one side in the first direction is fixed to the base, and the portion engaging with the second engaging portion on the other side in the first direction may also be fixed to the cover member.

[0056] In addition, in the lens driving unit,

[0057] The first engaging portion may be formed by bending a strip-shaped metal member into a predetermined shape.

[0058] In addition, in the lens driving unit,

[0059] The pair of friction surfaces may be included on the surface of the strip-shaped metal member.

[0060] In addition, in the lens driving unit,

[0061] The force by which the pair of friction surfaces clamp the drive shaft may be generated by the elasticity of the strip-shaped metal member. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] FIG. 1 is a perspective view of a lens driving unit according to the present embodiment.

[0063] FIG2 is an exploded perspective view of the lens driving unit.

[0064] FIG3 is a perspective view of the lens driving unit with a cover member removed.

[0065] FIG. 4 is a diagram showing a state in which the lens drive unit is removed from a cover member, as viewed from the optical axis direction.

[0066] FIG5 is a cross-sectional view taken along line VV in FIG4 .

[0067] FIG6 is a cross-sectional view of the support shaft and its surroundings taken along line VI-VI in FIG4 .

[0068] FIG. 7 is a diagram for explaining the magnetic force required for the supporting magnet.

[0069] FIG8 is an exploded perspective view of a conventional lens driving unit.

[0070] FIG. 9 is a diagram showing a state in which a part of the conventional lens driving unit is viewed in a cross section from the optical axis direction. DETAILED DESCRIPTION

[0071] Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

[0072] The lens driving unit of this embodiment can be built into a mobile terminal such as a smartphone, and is used to drive a lens or a lens group along the optical axis and focus (i.e., perform autofocus) in the camera of the mobile terminal.

[0073] As shown in Figures 1 to 6, the lens drive unit 1 includes a lens holder 2 that holds at least one lens R; a support shaft 3 that supports the lens holder 2 so that it can move in the direction D1 in which the optical axis C of the lens R extends (the optical axis direction (first direction)); and an actuator 4 that drives the lens holder 2 along the optical axis direction D1. The lens drive unit 1 also includes a housing 5 that surrounds the lens holder 2, support shaft 3, and actuator 4, and a substrate 6 for controlling the actuator 4 disposed within the housing 5.

[0074] The support shaft 3 magnetically supports the lens holder 2, enabling movement along the optical axis D1. Specifically, the support shaft 3 extends along the optical axis D1 and is formed from a magnetic material such as iron (specifically, a ferromagnetic material). In this embodiment, the support shaft 3 is a cylindrical member extending along the optical axis D1, with the outer diameter being the same at all locations along the optical axis D1.

[0075] The actuator 4 is a so-called piezoelectric actuator having a piezoelectric element 42 . The actuator 4 in this embodiment is a smooth impact drive mechanism (SIDM).

[0076] Specifically, the actuator 4 includes a drive shaft 41 extending in the optical axis direction D1 and a piezoelectric element 42 connected to one end of the drive shaft 41 and extending and contracting in the optical axis direction D1. Furthermore, the actuator 4 includes a weight member 43 connected to the piezoelectric element 42 on the opposite side of the drive shaft 41.

[0077] The drive shaft 41 of this embodiment is a cylindrical shaft component extending along the optical axis direction D1. In addition, the piezoelectric element 42 is an element that converts input electrical energy into mechanical energy of expansion and contraction, that is, mechanical motion. For example, it is an element that converts input electrical energy into mechanical expansion and contraction motion through the piezoelectric effect. The piezoelectric element 42 uses this expansion and contraction motion to cause the drive shaft 41 to reciprocate along the optical axis direction D1. These drive shafts and piezoelectric elements 42 are connected by an adhesive. In addition, the counterweight portion 43 is designed to generate displacement caused by the expansion and contraction of the piezoelectric element 42 only on the side of the drive shaft 41.

[0078] The housing 5 includes a base 51 to which the support shaft 3 and the actuator 4 are fixed, and a cover member 52 that together with the base 51 constitutes the housing 5. The housing 5 of this embodiment has a substantially rectangular parallelepiped shape and a substantially square shape when viewed from the optical axis direction D1.

[0079] The base 51 extends in a direction perpendicular to the optical axis direction D1 and has a first optical path opening 511 extending through the center of the base 51 along the optical axis direction D1. Furthermore, the base 51 has a first retaining portion 512 for retaining the support shaft 3 and a second retaining portion 513 for retaining the actuator 4. These first retaining portion 512 and second retaining portion 513 are arranged at two corners (a first corner 51a and a second corner 51b) of the base 51 that are opposite to a predetermined diagonal direction (a second direction) D2 when viewed from the optical axis direction D1.

[0080] In this embodiment, the first retaining portion 512 is a through-hole extending along the optical axis direction D1. With one end of the support shaft 3 inserted therein, the support shaft 3 is secured to the first retaining portion (through-hole) 512 (see FIG6 ). Furthermore, the second retaining portion 513 is also a through-hole extending along the optical axis direction D1. With the weight 43 of the actuator 4 inserted therein, the actuator 4 (weight 43) is secured to the second retaining portion 513 (see FIG5 ).

[0081] The cover component 52 has a plate-shaped portion 521 extending in a direction perpendicular to the optical axis direction D1, and a peripheral wall portion 522 extending from the periphery of the plate-shaped portion 521 toward the side of the base 51. The plate-shaped portion 521 has a first optical path opening portion 523 in the central portion that penetrates along the optical axis direction D1. In addition, the plate-shaped portion 521 has a cover-side retaining portion 524 and a through hole 525 that penetrates along the optical axis direction D1 at a position corresponding to the first retaining portion 512 and the second retaining portion 513 of the base 51. The drive shaft 41 of the actuator 4 (more specifically, the front end portion of the drive shaft 41) is inserted into the through hole 525 and can reciprocate (vibrate) along the optical axis direction D1. In addition, the cover-side retaining portion 524 of this embodiment is a through hole that penetrates along the optical axis direction D1, and the support shaft 3 is fixed to the cover-side retaining portion 524 when the other end of the support shaft 3 is inserted.

[0082] The lens holder 2 includes a holder body 20 for holding the lens R or lens group (a plurality of lenses), a first engaging portion 21 for engaging with the actuator 4, and a second engaging portion 22 for engaging with the support shaft 3. Furthermore, the lens holder 2 includes a detection magnet 23 for detecting the position or amount of movement of the lens holder 2 in the optical axis direction D1.

[0083] The retaining body 20 is a cylindrical or frame-shaped component that holds the lens R or lens assembly, surrounding the lens R or lens assembly (or multiple lenses). In this embodiment, the retaining body 20 is made of resin and holds a single lens R. Furthermore, when the retaining body 20 holds a lens assembly including multiple lenses R, it holds each lens R so that its optical axis C remains aligned.

[0084] The first engaging portion 21 has a pair of friction surfaces 211 (see FIG5 ) for clamping the drive shaft 41 of the actuator 4. The first engaging portion 21 is disposed at one end of the retaining portion body 20 in a predetermined diagonal direction D2, which is the direction connecting the first corner 51a and the second corner 51b of the base 51 (specifically, the direction connecting the support shaft 3 and the actuator 4). The first engaging portion 21 of this embodiment is formed by bending a metal strip-like member into a predetermined shape.

[0085] The pair of friction surfaces 211 of the first engaging portion 21 extend in a planar direction perpendicular to a clamping direction (third direction) D3 perpendicular to both the optical axis direction D1 and the diagonal direction D2, respectively, and clamp the drive shaft 41 along the clamping direction. The clamping force exerted by the pair of friction surfaces 211 on the drive shaft 41 is a force generated by the elastic force (resilient properties) of the first engaging portion 21 (metallic band-shaped member), and is set so that a predetermined frictional force acts between the pair of friction surfaces 211 and the drive shaft 41.

[0086] The second engaging portion 22 includes an insertion portion 220 that penetrates along the optical axis direction D1 and into which the support shaft 3 is inserted, and a supporting magnet 225 that applies magnetic attraction to the support shaft 3 . The second engaging portion 22 is disposed at the other end of the holding portion body 20 in the diagonal direction D2 .

[0087] The insertion portion 220 includes a plurality of extension members 221 extending from the holder body 20 toward the other side of the diagonal direction D2 (away from the holder body 20). The extension members 221 are spaced apart in the optical axis direction D1 and extend from the holder body 20. In the insertion portion 220 of this embodiment, a pair of extension members 221 are spaced apart in the optical axis direction D1 and extend from the holder body 20.

[0088] Each extension portion 221 is a plate-like portion extending in a planar direction perpendicular to the optical axis direction D1 and is spaced apart along the optical axis direction D1. In this embodiment, the extension portions 221 are spaced apart along the optical axis direction D1 so that the center of gravity G of the lens holding portion 2, when holding the lens R, is located at an arbitrary position between a pair of extension portions 221 in the optical axis direction D1 (see FIG7 ).

[0089] In addition, each extension portion 221 has a through hole (insertion hole) 222 extending along the optical axis D1 at an overlapping position when viewed from the optical axis D1. The through hole 222 of this embodiment is a circular hole, and the inner diameter of each through hole 222 is only slightly larger than or equal to the outer diameter of the support shaft 3.

[0090] The supporting magnets 225 are positioned along the diagonal direction D2 to press the inner circumferential surface 223 of the through-hole (through-hole) 222 of each extension portion 221 against the support shaft 3. Specifically, the supporting magnets 225 are positioned on the other side of the support shaft 3 (the right side in FIG6 ) along the diagonal direction D2. More specifically, the supporting magnets 225 are positioned on the other side of each extension portion 221 along the diagonal direction D2. The supporting magnets 225 have magnetic poles arranged along the diagonal direction D2 and extend from one extension portion 221 to the other extension portion 221 along the optical axis direction D1.

[0091] The strength of the supporting magnet 225 (magnetic attraction) is set so that when the lens drive unit 1 is arranged so that the optical axis direction D1 is aligned with the vertical direction, the lens holding portion 2 holding the lens R does not wobble (tilt) relative to the support shaft 3. The lens drive unit 1 of this embodiment is described below.

[0092] As shown in FIG7 , the distance from the center of gravity G of the lens holder 2 holding the lens R to the axis of the support shaft 3 is L1. The distances from the center of gravity G of the support shaft 3 in the optical axis direction D1 to the contact points α1 and α2 with the inner circumferential surface 223 of each extension 221 (in FIG7 , the center position of the inner circumferential surface 223 in the optical axis direction D1) are L2. The force (gravity) applied to the center of gravity G is F1, and the force from the magnetic attraction of the support magnet 225 is F2. The contact point α1 is considered to be the contact point in the inverted state, which will be described later, and the contact point α2 is considered to be the contact point in the upright state, which will be described later.

[0093] Furthermore, in this embodiment, the situation in which the axial center direction of the support shaft 3 is consistent with the vertical direction and the direction in which the lens holding part 2 is away from the base 51 is regarded as the upper side (the posture shown in FIG. 7 ) is regarded as the upright situation, the situation opposite to the upright situation (the direction in which the lens holding part 2 is away from the base 51 is regarded as the lower side) is regarded as the inverted situation, and the situation in which the axial center of the support shaft 3 is consistent with the horizontal direction and the lens holding part 2 is located on the lower side relative to the support shaft 3 is regarded as the horizontal situation, then the following relationship holds:

[0094] When upright: L1×F1=L2×F2…(1)

[0095] Inverted: L1×F1=L2×F2…(2)

[0096] When horizontal: F1=F2…(3)

[0097] In the lens drive unit 1 of this embodiment, L1 = 7.5 mm, L2 = 1.5 mm, and the weight of the lens holding portion 2 holding the lens R is 1.5 g.

[0098] F1=mfg=1.5fg=15mN

[0099] Therefore, we can obtain:

[0100] According to (1) above, F2 = 75 mN

[0101] According to (2) above, F2 = 75 mN

[0102] According to (3) above, F2 = 15 mN

[0103] If the safety factor is set to 2,

[0104] F2=150mN=15gf

[0105] In summary, the magnetic attraction force of the support magnet 225 is set to 15 gf. In the above calculation, the engagement between the first engagement portion 21 of the lens holder 2 and the actuator 4 is not considered. The lens holder 2 holding the lens R is supported only by the support shaft 3.

[0106] 1 to 6 , the detection magnet 23 is disposed on the peripheral surface of the holding portion main body 20. The detection magnet 23 of this embodiment is disposed at a position facing the substrate 6 on the peripheral surface of the holding portion main body 20 (see FIG. 4 ).

[0107] The substrate 6 includes a circuit 61 for supplying power to the piezoelectric element 42 of the actuator 4, and a position sensor 62 for detecting the position or movement amount in the optical axis direction D1 of the lens holder 2. The position sensor 62 in this embodiment is a Hall element.

[0108] In the lens drive unit 1 constructed as described above, when power is supplied from the circuit unit 61 to the piezoelectric element 42 in the actuator 4, the piezoelectric element 42 vibrates (expands) along the optical axis D1. This vibration causes the drive shaft 41 to reciprocate along the optical axis D1, and this reciprocating motion causes the lens holder 2 to move axially (in the optical axis D1) along the drive shaft 41. Consequently, the lens R in the camera of a mobile device such as a smartphone incorporating this lens drive unit 1 moves along the optical axis D1, enabling autofocusing.

[0109] More specifically, by applying a rectangular wave with a predetermined duty cycle to the piezoelectric element 42, the displacement of the drive shaft 41 becomes triangular. By varying the duty cycle of the rectangular wave, triangular waves with different inclinations are generated when the amplitude rises and falls. The drive mechanism of the actuator 4 also utilizes this principle.

[0110] For example, by slowly moving the drive shaft 41 in the direction of extension of the piezoelectric element 42, the lens holder 2, which is engaged with the drive shaft 41 via the pair of friction surfaces 211, also moves in conjunction with the movement in the extension direction. At the moment when the static friction between the pair of friction surfaces 211 and the drive shaft 41 is exceeded, if the drive shaft 41 is moved in the direction of contraction of the piezoelectric element 42, the lens holder 2 is retained in its original position due to inertial force. In this manner, by repeatedly reciprocating the axial direction of the drive shaft 41, the lens holder 2 is moved in the axial direction of the drive shaft 41 (the optical axis direction D1).

[0111] The lens drive unit 1 described above includes a lens holding portion 2 that holds at least one lens R, a support shaft 3 that supports the lens holding portion 2 so as to be movable along the optical axis direction (first direction D1) of the lens R, an actuator 4 having a drive shaft 41 that extends in the optical axis direction D1 and vibrates in the optical axis direction D1, and a base 51 to which the support shaft 3 and the actuator 4 are fixed. Furthermore, the lens holding portion 2 has a pair of friction surfaces 211 that clamp the drive shaft 41.

[0112] In this manner, while the support shaft 3 supports the lens holder 2 so as to be movable in the optical axis direction D1, the actuator 4 supplies a driving force for moving the lens holder 2 along the optical axis direction D1. This structure can suppress the load applied to the actuator 4 due to the weight of the lens R or the lens holder 2. In other words, the load is less likely to be applied to the actuator 4.

[0113] In the lens drive unit 1 of this embodiment, the actuator 4 includes a piezoelectric element 42 connected to one end of the drive shaft 41 and reciprocatingly moving the drive shaft 41 along the optical axis direction D1 by expanding and contracting along the optical axis direction (first direction) D1 .

[0114] Furthermore, in the lens driving unit 1 of the present embodiment, the support shaft 3 supports the lens holding portion 2 by magnetic force so as to be movable in the optical axis direction D1 .

[0115] According to this structure, by adjusting the magnitude of the magnetic force, the following structure can be easily achieved: when the driving force from the actuator 4 is not applied to the lens holding part 2, the position of the lens holding part 2 in the optical axis direction relative to the support shaft 3 is fixed, and when the driving force from the actuator 4 is applied to the lens holding part 2, the lens holding part 2 is allowed to move relative to the support shaft 3 along the optical axis direction D1.

[0116] In the lens driving unit 1 of the present embodiment, the support shaft 3 is formed of a magnet, and the lens holding portion 2 includes the second engaging portion 22 that engages with the support shaft 3 .

[0117] In addition, in the lens drive unit 1 of this embodiment, the second engaging portion 22 has a through hole (insertion hole) 222 that passes through along the optical axis direction (first direction) D1 and through which the support shaft 3 is inserted, and a supporting magnet (magnet) 225 that is arranged at a position pressing the inner peripheral surface 223 of the through hole 222 along the diagonal direction (second direction) D2 relative to the support shaft 3.

[0118] In this manner, by utilizing the magnetic force of the supporting magnet 225 , it is possible to easily realize a structure in which the support shaft 3 supports the lens holding portion 2 so as to be movable in the optical axis direction D1 .

[0119] In addition, in the lens driving unit 1 of the present embodiment, the lens holding portion 2 has a holding portion main body 20 surrounding the lens R, and the first snap-fit ​​portion 21 and the second snap-fit ​​portion 22 are arranged on both sides of the holding portion main body 20 in a specified radial direction (in the example of the present embodiment, the diagonal direction D2) of the lens R when viewed from the optical axis direction (first direction) D1.

[0120] In this way, by arranging the first locking portion 21 on the opposite side of the diagonal direction D2 of the retaining portion main body 20 relative to the second locking portion 22, the force from the retaining portion main body 20 (such as the force generated by the weight of the retaining portion main body 20 or the lens R itself), i.e., the load, applied to the support shaft 3 through the second locking portion 22 can be suppressed.

[0121] Furthermore, in the lens drive unit 1 of the present embodiment, the pair of friction surfaces 211 extend in a plane direction perpendicular to the clamping direction (third direction) D3 and clamp the drive shaft 41 in the clamping direction D3 .

[0122] Due to the magnetic force (magnetic attraction) of the supporting magnets 225, the inner circumferential surfaces 223 of the through-hole 222 are pressed in the diagonal direction D2 relative to the support shaft 3, thereby supporting the lens holder 2 on the support shaft 3. Consequently, when a device including the lens drive unit 1 is subjected to an impact, the lens holder 2 may sometimes move slightly relative to the support shaft 3 only in the diagonal direction D2 (the direction in which the inner circumferential surfaces 223 move away from the support shaft 3). However, because the pair of friction surfaces 211 clamp the drive shaft 41 in the clamping direction D3 (a direction orthogonal to the diagonal direction D2), the pair of friction surfaces 211 can move relative to the drive shaft 41 in the diagonal direction D2. This prevents a large load from being applied to the actuator 4 (drive shaft 41) due to movement of the lens holder 2 in the diagonal direction D2.

[0123] In addition, in the lens driving unit 1 of this embodiment, the lens holding part 2 has a holding part main body 20 surrounding the lens R, and a plurality of extension parts 221 respectively spaced apart in the optical axis direction (first direction) D1 and extending from the holding part main body 20, and the plurality of extension parts 221 respectively have insertion holes 222 at overlapping positions when viewed from the optical axis direction D1.

[0124] Compared with a block-shaped second engaging portion occupying the entire arrangement area of ​​the plurality of extension portions 221 , the weight can be reduced. Moreover, since the plurality of extension portions 221 are arranged at intervals along the optical axis direction D1 , the posture of the lens holder 2 relative to the support shaft 3 is stabilized.

[0125] In addition, in the lens driving unit 1 of the present embodiment, the lens holding part 2 has a holding part main body 20 surrounding the lens R, and a pair of extension parts 221 spaced apart in the optical axis direction (first direction) D1 and extending from the holding part main body 20. The pair of extension parts 221 are included in the second engaging part 22 and can be moved in the optical axis direction D1 relative to the support shaft 3 and engaged with the support shaft 3. The center of gravity G of the lens holding part 2 in the state of holding the lens R is located between the pair of extension parts 221 in the optical axis direction D1.

[0126] In this manner, since the center of gravity G of the lens holding portion 2 and the like is located between the pair of extension portions 221 in the optical axis direction D1, when the lens drive unit 1 is in a posture such that the extension direction of the support shaft 3 (i.e., the optical axis direction D1) is in the vertical direction, the direction of the force (such as the force generated by the weight of the lens holding portion and the like) applied to the support shaft 3 through the inner circumferential surfaces 223 of the insertion holes 222 of the pair of extension portions 221 is reversed. Thus, by changing the direction of the force applied to the support shaft 3, the load on the support shaft 3 is suppressed.

[0127] Furthermore, the lens driving unit 1 of the present embodiment includes a cover member 52 that constitutes the housing 5 together with the base 51 .

[0128] According to the above structure, the actuator 4 , the support shaft 3 , the lens holding portion 2 and other components are surrounded by the housing 5 and protected.

[0129] Furthermore, in the lens drive unit 1 of the present embodiment, a portion of the support shaft 3 that engages with the second engaging portion 22 (in the example of the present embodiment, the portion extending from the extension 221 on one side to the extension 221 on the other side in the optical axis direction (first direction) D1) is fixed to the base 51, while a portion that engages with the second engaging portion 22 on the other side in the optical axis direction D1 is fixed to the cover member 52. In this manner, by fixing the housing 5 on both sides of the engaging portion with the second engaging portion 22 of the support shaft 3, the strength of the support shaft 3 against the force applied by the lens holding portion 2 can be increased, thereby preventing damage to the support shaft 3 when a mobile terminal or the like equipped with the lens drive unit is subjected to an impact.

[0130] In the lens drive unit 1 of this embodiment, the first engaging portion 21 is formed by bending a strip-shaped metal member into a predetermined shape. Thus, by bending the strip-shaped metal member to form the first engaging portion 21, the structure of the first engaging portion 21 can be simplified.

[0131] Furthermore, in the lens drive unit 1 of this embodiment, the pair of friction surfaces 211 are included on the surface of the plate-shaped metal component. Thus, by using a single component (the plate-shaped metal component) to clamp the drive shaft 41 of the actuator 4, the number of components can be reduced compared to a structure in which the drive shaft 41 is clamped by multiple components.

[0132] In the lens drive unit 1 of this embodiment, the force of the pair of friction surfaces 211 clamping the drive shaft 41 is generated by the elasticity of the plate-shaped metal member.

[0133] Furthermore, the lens drive unit of the present invention is not limited to the aforementioned embodiments. Various modifications are possible without departing from the spirit of the present invention. For example, the structure of one embodiment may be supplemented with the structure of another embodiment, or a portion of the structure of one embodiment may be replaced with that of another embodiment. Furthermore, a portion of the structure of one embodiment may be deleted.

[0134] In the lens drive unit 1 of the above embodiment, the support magnet 225 is arranged on the side of the holding portion body 20 relative to the support shaft 3 in the diagonal direction D2 (the right side in FIG6 ), but the present invention is not limited to this structure. The support magnet 225 may also be arranged on the opposite side of the holding portion body 20 relative to the support shaft 3 in the diagonal direction D2 (the left side in FIG6 ).

[0135] Furthermore, in the lens drive unit 1 of the above-described embodiment, the magnetic attraction of the supporting magnet 225 of the second engaging portion 22 constituting the lens holding portion 2 is applied to the support shaft 3 formed of a magnet, thereby supporting the lens holding portion 2 so that it can move in the optical axis direction D1. However, this is not limited to this structure. For example, a structure in which the support shaft 3 is formed of a magnet, the second engaging portion 22 of the lens holding portion 2 is disposed on a magnet (specifically, a strong magnet such as iron), and the magnetic attraction of the support shaft 3 is applied to the magnet of the second engaging portion 22, thereby supporting the lens holding portion 2 so that it can move in the optical axis direction D1 can also be employed.

[0136] The support shaft 3 is not limited to a specific structure for supporting the lens holder 2 so as to be movable in the optical axis direction D1. The support shaft 3 may support the lens holder 2 so as to be movable in the optical axis direction D1 without using magnetic force.

[0137] In addition, in the lens driving unit 1 of the above embodiment, the support shaft 3 and the actuator 4 are arranged on both sides of the lens holding portion 2 in the radial direction (diagonal direction D2) of the lens R, that is, the lens R is arranged in a position clamped in the radial direction (in detail, in the diameter direction of the position of the optical axis C of the lens R), but can be arranged in other positions.

[0138] In addition, in the lens driving unit 1 of the above embodiment, the pair of friction surfaces 211 are arranged on one component, but the present invention is not limited to this structure. The pair of friction surfaces 211 can also be arranged on different components.

[0139] In the insertion portion 220 of the lens drive unit 1 in the above embodiment, the through hole (insertion hole) 222 through which the support shaft 3 is inserted is a circular hole, but may be a polygonal hole.

[0140] In the lens drive unit 1 of the above embodiment, the support shaft 3 supports the lens holder 2 by magnetic force so that it can move in the optical axis direction D1, but the present invention is not limited to this structure. As long as the support shaft 3 supports the lens holder 2 so that it can move in the optical axis direction D1, other structures are also possible.

[0141] To better illustrate the present invention, the present invention has been appropriately and fully described above through embodiments with reference to the accompanying drawings. It should be noted that those skilled in the art may easily modify and / or improve the above embodiments. Therefore, as long as the modified or improved embodiments implemented by those skilled in the art do not depart from the scope of the claims set forth in the claims, the modified or improved embodiments should be interpreted as being included within the scope of the claims.

[0142] Description of reference numerals:

[0143] 1: Lens drive unit, 2: Lens holding portion, 20: Holding portion body, 21: First engaging portion, 211: Friction surface, 22: Second engaging portion, 220: Insertion portion, 221: Extension portion, 222: Through hole (insertion hole), 223: Inner circumferential surface, 225: Support magnet (magnet), 23: Detection magnet, 3: Support shaft, 4: Actuator, 41: Drive shaft, 42: Piezoelectric element, 43: Counterweight, 5: Housing, 51: Base, 51a: First corner portion, 51b: Second corner portion, 511: First optical path opening, 512: First holding portion, 513: Second holding portion, 52: Cover component, 521: Plate-shaped portion, 522: Peripheral wall portion, 523: First optical path opening, 524: Cover side holding portion, 525: Through hole, 6: substrate, 61: circuit part, 62: position sensor, 100: lens drive unit, 101: device body, 102: holding component, 102a: first corner part, 102c: third corner part, 120c: third support column, 121: actuator holding part, 122: limiting part storage groove, 103: cover, 104: actuator, 141: piezoelectric element, 142: drive shaft, 105: Moving part, 106: Moving part main body, 161: Rotation limiting part, 107: Engaging part, 171: Engaging part main body, 172: Driving bearing part, 172a: First supporting part, 172b: Second supporting part, 173: Elastic body, 173a: Pressing part, C: Optical axis, D1: Optical axis direction, D2: Diagonal direction, D3: Clamping direction, G: Center of gravity, R: Lens, α1, α2: Contact points.

Claims

1. A lens driving unit, comprising: a lens holding portion that holds at least one lens; A support shaft that supports the lens holding portion to enable movement in a first direction, that is, an optical axis direction of the lens; an actuator having a drive shaft extending in a first direction and vibrating in the first direction; and a base to which the support shaft and the actuator are fixed, The lens holding portion includes a first engaging portion having a pair of friction surfaces that sandwich the drive shaft.

2. The lens driving unit according to claim 1, wherein: The actuator includes a piezoelectric element connected to one end of the drive shaft and causing the drive shaft to reciprocate in the first direction by expanding and contracting in the first direction.

3. The lens driving unit according to claim 1 or 2, wherein: The support shaft supports the lens holding portion by magnetic force so as to be movable in the first direction.

4. The lens driving unit according to any one of claims 1 to 3, wherein: The support shaft extends in the first direction and is formed by a magnet, The lens holding portion includes a second engaging portion that engages with the support shaft.

5. The lens driving unit according to claim 4, wherein: The second engaging portion comprises: an insertion hole, which penetrates along the first direction and through which the support shaft is inserted; and The magnet is disposed at a position that presses the inner peripheral surface of the insertion hole against the support shaft along a second direction perpendicular to the first direction.

6. The lens driving unit according to claim 4 or 5, wherein: The lens holding part has a holding part body surrounding the at least one lens. The first engaging portion and the second engaging portion are arranged on both sides of the holding portion body in a radial direction of the lens when viewed from the first direction.

7. The lens driving unit according to any one of claims 1 to 6, wherein: The pair of friction surfaces respectively extend along a plane direction orthogonal to a third direction and clamp the drive shaft in the third direction, and the third direction is respectively orthogonal to the first direction and the second direction.

8. The lens driving unit according to claim 5, wherein: The lens holding portion comprises: a holding portion body surrounding the at least one lens; and A plurality of extension portions, which are spaced apart in the first direction and extend from the holding portion body, The plurality of extensions each have the insertion hole at a position where they overlap when viewed from the first direction.

9. The lens driving unit according to any one of claims 4 to 6 and 8, wherein: The lens holding portion comprises: a holding portion body surrounding the at least one lens; and A pair of extensions, which are spaced apart in the first direction and extend from the holding portion body, The pair of extensions are included in the second engagement portion and are movable in the first direction relative to the support shaft and are engaged with the support shaft. The center of gravity of the lens holding portion in a state of holding the at least one lens is located between the pair of extension portions in the first direction.

10. The lens driving unit according to any one of claims 4 to 6, 8 and 9, wherein: A cover member is provided which forms a housing together with the base.

11. The lens driving unit according to claim 10, wherein: In the support shaft, a portion engaging with the second engaging portion on one side in the first direction is fixed to the base, and a portion engaging with the second engaging portion on the other side in the first direction is fixed to the cover member.

12. The lens driving unit according to any one of claims 1 to 11, wherein: The first engaging portion is formed by bending a strip-shaped metal member into a predetermined shape.

13. The lens driving unit according to claim 12, wherein: The pair of friction surfaces are included in the surface of the strip-shaped metal member.

14. The lens driving unit according to claim 13, wherein: The force for the pair of friction surfaces to clamp the drive shaft is generated by the elasticity of the band-shaped metal member.

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