JP2020013065A - Lens drive device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lens driving device capable of miniaturization. SOLUTION: In a lens driving device 1, when a leaf spring member 51 is elastically deformed in a direction in which a tip portion 51a is separated from a lens frame body 40, a tip portion 51a and a connecting portion 51c of the leaf spring member 51 are formed by a base member 30. And the situation of contacting the cap 10 does not occur or is less likely to occur. Therefore, the situation where the leaf spring member 51 comes into contact with the outer peripheral wall portion 34 of the base member 30 and the outer peripheral wall portion 12 of the cap 10 and the function of the lens driving device is hindered is suppressed. Therefore, according to the lens driving device 1, the base member 30 can be made smaller while avoiding deterioration or deterioration of the function, and miniaturization can be realized. [Selection diagram] FIG. 7

Description

  The present invention relates to a lens driving device.

  As a lens driving device used in an imaging device mounted on a mobile phone or the like, Patent Document 1 below discloses a lens driving device that moves a lens frame in which a lens is fitted by a piezoelectric actuator in an optical axis direction. In the lens driving device of Patent Literature 1, a leaf spring member disposed along the outer periphery of the lens frame urges a piezoelectric actuator disposed on the outer periphery of the lens frame toward the lens frame, thereby achieving a lens. The frame is frictionally engaged with the piezoelectric actuator.

Japanese Patent No. 6024798

  In the above-described lens driving device, the size of the housing that surrounds the outer periphery of the lens frame is reduced, so that the size can be reduced. However, when the housing is simply reduced in size, the leaf spring member may come into contact with the housing when elastically deformed, thereby impairing the function of the lens driving device.

  An object of the present invention is to provide a lens driving device that can be downsized.

  A lens driving device according to one aspect of the present invention includes a lower support member, a lens frame positioned above the lower support member, to which a lens is attached, and an outer periphery of the lens frame along an optical axis direction of the lens. Extending along the optical axis of the lens, the lower end of which is fixed to the lower supporting portion, and an actuator extending along the outer periphery of the lens frame, and the upper end of the actuator is connected to the lens frame side. A first end portion frictionally engaged with the outer periphery of the upper end portion so as to urge the upper end portion, and a leaf spring member having a second end portion attached to the lens frame. A notch in a region overlapping with the leaf spring member when viewed from a direction perpendicular to the optical axis.

  In the above-mentioned lens driving device, the notch of the lower support member prevents or hardly causes the leaf spring member from contacting the lower support member. Therefore, the size of the lower support member can be reduced without obstructing the function of the lens driving device, and the size of the lens driving device can be reduced.

  In the lens driving device according to another aspect of the present invention, the leaf spring member has a connection portion interposed between the first end portion and the second end portion, and the cutout portion is orthogonal to the optical axis. It is provided on the lower support member in a region overlapping with the connection portion of the leaf spring member when viewed from the direction.

  In the lens driving device according to another aspect of the present invention, the first end and the second end of the leaf spring member overlap the lower support member when viewed from a direction orthogonal to the optical axis.

  In the lens driving device according to another aspect of the present invention, the lens driving device further includes an upper support member stacked on the upper side of the lower support member, wherein the upper support member overlaps with the leaf spring member when viewed from a direction orthogonal to the optical axis. It has an upper cutout.

  In the lens driving device according to another aspect of the present invention, the actuator is joined to the upper end of the piezoelectric element, the piezoelectric element extending in the expansion and contraction direction and having the upper end and the lower end, and the leaf spring member frictionally contacts the outer periphery. A lower end of the piezoelectric element is fixed to the lower support member.

  According to various aspects of the present invention, there is provided a lens driving device that can be downsized.

1 is an exploded perspective view showing a lens driving device according to one embodiment. FIG. 2 is a perspective view illustrating a lens driving unit of FIG. 1. FIG. 3 is a perspective view showing a lens driving unit without a cap. FIG. 4 is a plan view of the lens driving unit shown in FIG. 3. FIG. 4 is a side view showing an actuator and a friction engagement member. It is the figure which showed the bending amount in the bending part of the leaf spring member. FIG. 2 is a side view illustrating the lens driving unit of FIG. 1. It is a side view showing a lens drive part of a different mode.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description, the same elements or elements having the same functions will be denoted by the same reference symbols, without redundant description.

  As shown in FIG. 1, the lens driving device 1 includes a lens driving unit 2 and a cover 3 that covers the lens driving unit 2, and has a lens optical axis L that is an optical axis of a lens 4 to be attached. The lens 4 may be a single lens or a lens barrel including a plurality of lenses.

  As shown in FIG. 2, the lens driving unit 2 has a substantially quadrangular prism shape, and includes a cap (upper support member) 10 and a driving body 20. The cap 10 and the drive main body 20 are overlapped along the direction of the lens optical axis L. Further, both the cap 10 and the drive main body 20 have through holes 10a and 20b extending along the direction of the lens optical axis L, respectively. In the present embodiment, the lens 4 is screwed to the drive main body 20 so as to be accommodated in the through hole 20 a of the drive main body 20. For example, a male screw may be formed on the outer peripheral surface of the lens 4, and a female screw may be formed on the inner peripheral surface of the through hole 20 a of the drive main body 20. The diameter of the through hole 20a of the drive main body 20 is designed to be the same as the diameter of the lens 4, and the through hole 10a of the cap 10 is also designed to be approximately the same as the diameter of the lens 4.

  Hereinafter, the configuration of the drive main unit 20 will be described in more detail with reference to FIGS.

  As shown in FIG. 3, the drive main body 20 includes a base member (lower support member) 30 and a lens frame 40.

  The base member 30 extends in a direction orthogonal to the lens optical axis L. As shown in FIG. 4, the base member 30 has a substantially square shape in plan view (that is, when viewed from the direction of the lens optical axis L). At one corner of the base member 30, an attachment portion 31 to which an actuator 54 described later is attached is provided. In the present embodiment, the mounting portion 31 is an opening that accommodates and fixes the weight portion 57 of the actuator 54. Further, the base member 30 is provided with a side wall 32 at a corner diagonally opposite to the corner at which the mounting portion 31 is provided. The side wall 32 is provided with a notch 33 for accommodating the protrusion 42 of the lens frame 40. The base member 30 is made of, for example, a resin material (liquid crystal polymer or the like) containing a filler made of glass, an inorganic material, or the like. The base member 30 can be formed by, for example, injection molding.

  The outer peripheral wall portion 34 is provided around the lens frame 40 on the base member 30. The height of the outer peripheral wall 34 is designed to be, for example, about half the height of the lens frame 40. The outer peripheral wall portion 34 has a notch 34a described later, and surrounds the lens frame 40 other than the portion corresponding to the notch 34a. In the present embodiment, the outer peripheral wall portion 12 corresponding to the outer peripheral wall portion 34 of the base member 30 is provided on the cap 10 stacked on the upper side of the base member 30. The height of the outer peripheral wall 12 is designed to be, for example, about half the height of the lens frame 40. In the present embodiment, the height of the base member 30 and the height of the cap 10 are designed to be substantially the same, and the outer peripheral wall portions 12 and 34 are also designed to be substantially the same. The outer peripheral wall 12 of the cap 10 and the outer peripheral wall 34 of the base member 30 are in contact with each other and are joined by an adhesive. The outer peripheral wall 12 of the cap 10 is provided with a cutout (upper cutout) 12 a in a region corresponding to the outer peripheral wall 34 of the base member 30.

  The lens frame 40 extends in a direction orthogonal to the lens optical axis L, similarly to the base member 30. The lens frame 40 is arranged on the upper side with respect to the lens optical axis L so as to be parallel to the base member 30. The lens frame 40 has a through hole 40a corresponding to the above-described through hole 20a. As shown in FIG. 4, the lens frame 40 has a substantially square shape in plan view similarly to the base member 30. An actuator 54 is attached to the outer periphery of the lens frame 40 at a portion corresponding to a corner where the attachment portion 31 of the base member 30 is provided by using a friction engagement member 50. The lens frame 40 has a housing portion 43 for housing a fixed end portion 51b of a leaf spring member 51 described later. The fixed end portion 51b of the leaf spring member 51 is held and fixed in the housing portion 43 to form a fulcrum P2 of the leaf spring member 51.

  The lens frame 40 is housed between the cap 10 and the base member 30. The cover 3 illustrated in FIG. 1 covers the entire lens driving unit 2 configured to accommodate the lens frame 40 between the cap 10 and the base member 30 from above. A slight gap is provided between the inner surface of the cover 3 and the outer peripheral surfaces of the cap 10 and the base member 30, and the cover 3 and the base member 30 are bonded by the adhesive supplied to the gap. ing.

  The actuator 54 is a piezoelectric actuator provided with a smooth impact drive mechanism. As shown in FIG. 5, the actuator 54 includes a prismatic piezoelectric element 55, a drive shaft 56 joined to a top surface 55 a of the piezoelectric element 55, and a weight 57 joined to a bottom surface 55 b of the piezoelectric element 55. Including. An adhesive such as an epoxy adhesive can be used for joining the piezoelectric element 55 to the drive shaft 56 and the weight portion 57.

The piezoelectric element 55 is made of a piezoelectric material. Examples of the piezoelectric material include lead zirconate titanate (so-called PZT), quartz, lithium niobate (LiNbO ₃ ), and potassium tantalate niobate (K (Ta, Nb). ) _O 3), barium titanate (BaTiO _3), or an inorganic piezoelectric material such as lithium tantalate (LiTaO ₃₎ and strontium titanate (SrTiO _3). The piezoelectric element 55 can have a laminated structure in which a plurality of piezoelectric layers made of the above-described piezoelectric material and a plurality of electrode layers are alternately laminated. A pair of electrodes (not shown) connected to the electrode layer is provided on the side surface of the piezoelectric element 55, and when a voltage is applied to the piezoelectric element 55 by the pair of electrodes, the axis (Z in FIG. 5) is applied. (E.g., the axis of the piezoelectric ceramic). Therefore, expansion and contraction of the piezoelectric element 55 can be controlled by controlling the voltage applied between the pair of electrodes. The piezoelectric element 55 is not limited to the prismatic shape as long as it can expand and contract in one direction, and may be a cylindrical shape or the like.

  The drive shaft 56 is made of a composite resin material containing fibers such as carbon fibers. The drive shaft 56 has a columnar shape wider than the piezoelectric element 55, and is aligned with the Z-axis of the piezoelectric element 55.

  The weight portion 57 is formed of a material having a high specific gravity, such as tungsten or a tungsten alloy, and is designed to be heavier than the drive shaft 56. By making the weight 57 heavier than the drive shaft 56, when the piezoelectric element 55 expands and contracts, the weight 57 is less likely to be displaced, and the drive shaft 56 can be displaced more efficiently. The weight portion 57 has a rectangular flat plate shape, and is aligned with the Z-axis of the piezoelectric element 55. The actuator 54 has the weight portion 57 accommodated in the attachment portion 31 of the base member 30 and is fixed. At this time, it is designed such that the axis Z of the piezoelectric element 55 of the actuator 54 is parallel to the lens optical axis L. The weight portion 57 of the actuator 54 and the mounting portion 31 of the base member 30 can be fixed by bonding.

  The friction engagement member 50 frictionally engaged with the actuator 54 includes a leaf spring member 51 and a slider 52.

  The leaf spring member 51 is a band member having elasticity (for example, a band member made of stainless steel), and is arranged on the outer periphery of the lens frame 40. The leaf spring member 51 is made of an alloy plate material or a metal plate material, and is obtained by punching and bending a single plate material. The leaf spring member 51 is formed of one member, and has a configuration in which a plurality of members are not joined by, for example, welding. The leaf spring member 51 does not branch when viewed from the direction of the lens optical axis L or a direction perpendicular to the lens optical axis L (that is, a side direction).

  As shown in FIG. 5, the leaf spring member 51 extends along the outer periphery of the lens frame 40 and is substantially orthogonal to the lens optical axis L when viewed from the side. The leaf spring member 51 has a distal end 51a (first end) and a fixed end 51b (second end).

  The distal end 51 a is a free end of the leaf spring member 51 and is in contact with the drive shaft 56 of the actuator 54. The leaf spring member 51 urges the drive shaft 56 toward the lens frame 40 at the distal end portion 51a, and frictionally engages with the actuator 54. In the distal end portion 51a, a portion where the leaf spring member 51 and the drive shaft 56 are in contact is an action point P1 of the leaf spring member 51. The distal end 51a extends so as to be orthogonal to the lens optical axis L and the axis Z of the piezoelectric element 55 of the actuator 54, and the distal end 51a has a uniform width (that is, a length in the lens optical axis L direction). Have.

  The fixed end 51b is fixed to the lens frame 40. The fixed end 51b extends so as to be orthogonal to the lens optical axis L and the axis Z of the piezoelectric element 55 of the actuator 54, and the fixed end 51b has a uniform width. The width of the tip 51a is smaller than the width of the fixed end 51b. By thus narrowing the distal end portion 51a, the movable range of the distal end portion 51a that moves the drive shaft 56 in the Z-axis direction is increased. As a result, the drivable distance (stroke) of the leaf spring member 51 and the lens frame 40 is extended.

  A connecting portion 51c is interposed between the distal end portion 51a and the fixed end portion 51b, and the distal end portion 51a and the fixed end portion 51b are connected by the connecting portion 51c. The width of the connecting portion 51c is not uniform, and the width gradually decreases from the fixed end portion 51b toward the distal end portion 51a. The leaf spring member 51 has its height position (position with respect to the lens optical axis L) shifted at the connection portion 51c, and the height position of the center line of the distal end portion 51a is higher than the height position of the center line of the fixed end portion 51b. Is getting higher.

  A bent portion 53 is formed between the distal end portion 51a and the connection portion 51c. As shown in FIG. 6, the distal end portion 51 a is closer to the actuator 54 side than the connection portion 51 c by the bent portion 53. The amount of bending at the bending portion 53 affects the biasing force of the leaf spring member 51 and thereby also the frictional force of the friction engagement member 50. For example, as shown by the two-dot chain line in FIG. 6, in the leaf spring member 51 having a large amount of refraction at the bent portion 53, the urging force of the leaf spring member 51 increases, and the friction force of the friction engagement member 50 increases. Therefore, the frictional force of the friction engagement member 50 can be adjusted by adjusting the amount of bending at the bending portion 53.

  The slider 52 is fixed to a slider fixing portion 41 provided on the outer peripheral surface of the lens frame 40. A right-angled corner is defined on the outer peripheral surface of the slider fixing portion 41, and the slider 52 is a plate-like member (for example, a stainless steel plate-like member) bent at a right angle along the corner. is there.

  The distal end portion 51 a of the leaf spring member 51 and the slider 52 sandwich the drive shaft 56 of the actuator 54. At this time, since the leaf spring member 51 urges the actuator 54 toward the slider 52, a predetermined frictional force is generated between the friction engagement member 50 and the actuator 54, and the friction engagement member 50 Are frictionally engaged with the drive shaft 56 of the actuator 54. The lens frame 40 to which the friction engagement member 50 is attached also frictionally engages with the drive shaft 56 of the actuator 54 via the friction engagement member 50.

  In the lens driving device 1, when the actuator 54 expands and contracts, a speed difference between when the actuator 54 expands and when the actuator 54 contracts, so that the friction engagement member 50 frictionally engaged with the outer periphery of the drive shaft 56 of the actuator 54 is moved to the lens frame body. The actuator 54 is driven in the expansion and contraction direction of the actuator 54 (that is, in the Z-axis direction) together with the actuator 40.

  As shown in FIG. 4, the lens driving unit 2 includes a region corresponding to a corner different from the corner where the mounting portion 31 of the base member 30 is provided and the corner where the side wall 32 is provided. A circuit section 60 is provided. The circuit section 60 includes a flexible substrate and a position sensor unit. The flexible substrate is provided so as to cover the outer peripheral surface of the lens frame 40 along two sides sandwiching the corner where the circuit unit 60 is provided. On the flexible substrate, for example, a circuit and a wiring for controlling the voltage applied to the actuator 54 described above are formed. The magnetic sensor detects displacement of the lens frame 40 in the direction of the lens optical axis L by detecting a change in magnetic flux from a magnet provided on the lens frame 40.

  Here, the notch 34a of the outer peripheral wall 34 of the base member 30 and the notch 12a of the outer peripheral wall 12 of the cap 10 will be described with reference to FIG.

  The base member 30 has a cutout portion 34a formed in the outer peripheral wall portion 34 extending along the side where the leaf spring member 51 is located. The notch portion 34a extends along the outer peripheral wall portion 34. In the notch portion 34a, the upper end portion of the outer peripheral wall portion 34 is cut out at a substantially uniform height.

  The cap 10 also has a notch 12a formed in the outer peripheral wall 12 extending along the side where the leaf spring member 51 is located. The notch portion 12a extends along the outer peripheral wall portion 12, and the lower end portion of the outer peripheral wall portion 12 is cut out at a substantially uniform height in the notch portion 12a. In the present embodiment, the notch 12 a of the outer peripheral wall 12 of the cap 10 is formed in a region completely corresponding to the notch 34 a of the outer peripheral wall 34 of the base member 30.

  An escape hole 70 is defined by the notch 34 a of the outer peripheral wall 34 of the base member 30 and the notch 12 a of the outer peripheral wall 12 of the cap 10.

  As shown in the side view of FIG. 7, when viewed from a direction orthogonal to the lens optical axis L, a part of the distal end portion 51 a of the leaf spring member 51 and a part of the connection portion 51 c are exposed from the escape hole 70. In other words, the leaf spring member 51 does not overlap with any of the outer peripheral wall 34 of the base member 30 and the outer peripheral wall 12 of the cap 10 in the area of the escape hole 70 when viewed from a direction orthogonal to the lens optical axis L.

  Therefore, when the leaf spring member 51 is elastically deformed in a direction in which the distal end portion 51a is separated from the lens frame 40, the distal end portion 51a and the connection portion 51c of the leaf spring member 51 are connected to the outer peripheral wall portion 34 of the base member 30 and the cap. A situation in which the outer peripheral wall portion 10 contacts the outer peripheral wall portion 12 does not occur or is unlikely to occur. Therefore, a situation in which the function of the lens driving device 1 is hindered due to the leaf spring member 51 contacting the base member 30 or the cap 10 is suppressed. For example, when the leaf spring member 51 touches the base member 30 or the cap 10, or when the leaf spring member 51 rubs against the base member 30 or the cap 10, fine powder is generated, and the fine powder generates the fine powder. Function may be inhibited. Alternatively, when the leaf spring member 51 touches the base member 30 or the cap 10, elastic deformation of the leaf spring member 51 is hindered, and a situation in which desired driving characteristics cannot be realized may occur.

  According to the lens driving device 1 described above, the base member 30 can be reduced in size while avoiding a decrease or deterioration in function, and downsizing can be realized. In particular, as shown in FIG. 6, when the amount of bending at the bent portion 53 of the leaf spring member 51 is large, the leaf spring member 51 comes into contact with the outer peripheral wall 34 of the base member 30 and the outer peripheral wall 12 of the cap 10. The configuration in which the escape hole 70 is provided is effective because it becomes easy.

  In the present embodiment, since the leaf spring member 51 has the bent portion 53, the connecting portion 51c is a portion closest to the outer peripheral wall portion 34 of the base member 30 and the outer peripheral wall portion 12 of the cap 10. Therefore, the escape hole 70 may be provided at least in a region corresponding to the connection portion 51c. That is, as shown in FIG. 8, when viewed from a direction orthogonal to the lens optical axis L, the distal end portion 51a and the fixed end portion 51b of the leaf spring member 51 overlap the outer peripheral wall portions 12a and 34a. Is also good. Even in such an embodiment, the situation where the leaf spring member 51 contacts the outer peripheral wall 34 of the base member 30 and the outer peripheral wall 12 of the cap 10 is suppressed.

  The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments, and various changes can be made. For example, the drive shaft and the weight of the piezoelectric actuator can be omitted as appropriate, and the piezoelectric actuator may be composed of only piezoelectric elements. In addition, the actuator is not limited to the above-described piezoelectric actuator, and may be an electromagnetic drive type actuator including a magnet and a coil, or a drive type actuator using a shape memory alloy. Further, the lens driving device may not include the cap.

  DESCRIPTION OF SYMBOLS 1 ... Lens drive device, 10 ... Cap, 12 ... Outer peripheral wall part, 12a ... Notch part, 20 ... Drive main body part, 30 ... Base member, 34 ... Outer peripheral wall part, 34a ... Notch part, 40 ... Lens frame body, 50 ... Friction engagement member, 51 ... leaf spring member, 51a ... tip, 51b ... fixed end, 51c ... connection, 53 ... bend, 54 ... actuator, 55 ... piezoelectric element, 56 ... drive shaft, 57 ... Weight part, 70: escape hole, L: lens optical axis.

Claims (5)

A lower support member,
A lens frame that is located above the lower support member and to which a lens is attached;
An actuator that extends along the optical axis direction of the lens at the outer periphery of the lens frame, is extendable and contractible in the optical axis direction of the lens, and has a lower end fixed to the lower support portion;
A first end extending along an outer periphery of the lens frame and frictionally engaged with an outer periphery of the upper end to urge an upper end of the actuator toward the lens frame; A leaf spring member having a second end attached to the body;
The lens driving device, wherein the lower support member has a notch in a region overlapping with the leaf spring member when viewed from a direction orthogonal to the optical axis. The leaf spring member has a connecting portion interposed between the first end and the second end,
2. The lens driving device according to claim 1, wherein the cutout portion is provided in the lower support member in a region overlapping with the connection portion of the leaf spring member when viewed from a direction orthogonal to the optical axis. 3.   The lens driving device according to claim 2, wherein the first end and the second end of the leaf spring member overlap the lower support member when viewed from a direction orthogonal to the optical axis. Further comprising an upper support member stacked on the upper side of the lower support member,
4. The lens driving device according to claim 1, wherein the upper support member has an upper cutout in a region overlapping the leaf spring member when viewed from a direction orthogonal to the optical axis. 5. The actuator includes a piezoelectric element extending in the direction of expansion and contraction and having an upper end and a lower end, and a drive shaft joined to the upper end of the piezoelectric element and the leaf spring member is frictionally engaged with an outer periphery. And
The lens driving device according to claim 1, wherein a lower end of the piezoelectric element is fixed to the lower support member.

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