JP2020013063A - Lens drive device - Google Patents

Abstract

To provide a lens drive device with which impact resistance is improved.SOLUTION: In a lens drive device 1, the upper end of an actuator 54 is bonded to a cap 10 and the lower end is bonded to a base member 30. For this reason, the position and attribute of the actuator 54 are held by the cap 10 and the base member 30 with high accuracy. With the lens drive device 1, therefore, the possibility of the actuator 54 being broken by an impact if any applied is suppressed, and high impact resistance is realized.SELECTED DRAWING: Figure 6

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

  For example, an imaging device using the above-described lens driving device is required to have impact resistance enough to withstand an impact at the time of dropping, and a lens driving device is also required to have high impact resistance.

  The inventors of the present invention have found a technique capable of improving the impact resistance of a lens driving device after extensive research.

  An object of the present invention is to provide a lens driving device with improved impact resistance.

  The lens driving device according to one aspect of the present invention is a lower supporting member, a lens frame located above the lower supporting member, a lens frame to which a lens is attached, and a superimposed and bonded above the lower supporting member, An upper support member for accommodating the lens frame body between the lower support member and an upper end portion extending along the optical axis direction of the lens on the outer periphery of the lens frame body and capable of extending and contracting in the optical axis direction of the lens; Is attached to the upper support member and the lower end is attached to the lower support member.The actuator extends along the outer periphery of the lens frame, and biases the upper end of the actuator toward the lens frame. A leaf spring member having a first end frictionally engaged with the outer periphery of the upper end and a second end attached to the lens frame is provided.

  The actuator of the lens driving device has an upper end bonded to the upper support member and a lower end bonded to the lower support member. Therefore, the position and posture of the actuator are held with high accuracy by the upper support member and the lower support member. Therefore, in the above-described lens driving device, a situation in which the actuator is damaged even when an impact is applied is suppressed, and high impact resistance can be realized.

  In a lens driving device according to another aspect of the present invention, the upper support member has an opening into which the upper end of the actuator enters, and the actuator has an upper support at the outer periphery of the upper end that enters the opening of the upper support member. Adhered to the member.

  In the lens driving device according to another aspect of the present invention, the lower support member has an opening into which the lower end of the actuator enters, and the actuator has an outer periphery of the lower end that enters the opening of the lower support member. Adhered to the lower support member.

  In the lens driving device according to another aspect of the present invention, the lower support member has a rectangular shape when viewed from the optical axis direction of the lens and has a side wall that is bonded to the upper support member at one corner, The actuator is arranged at the corner where the side wall is provided.

  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 with improved impact resistance.

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 sectional drawing of the actuator periphery. FIG. 2 is a top view of the drive main unit of FIG. 1. It is sectional drawing in the adhesion part of the weight part of a piezoelectric actuator and a base member.

  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). An opening 31 to which an actuator 54 described later is attached is provided at one corner of the base member 30. In the present embodiment, the opening 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 where the opening 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 34 is provided at least at a corner where the opening 31 is provided. 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. The outer peripheral wall 12 is provided at least in a region corresponding to the outer peripheral wall 34 provided at a corner where the opening 31 is provided. 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 12a and 34a 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 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 opening 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 opening 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 57 of the actuator 54 and the opening 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.

  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 opening 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 holding state of the actuator 54 will be described with reference to FIGS.

  The actuator 54 is bonded to the cap 10 at the upper end as shown in FIGS. Specifically, an opening 13 is provided in a region of the cap 10 corresponding to the actuator 54, and the inner surface of the opening 13 and the outer peripheral surface of the upper end of the drive shaft 56 of the actuator 54 are bonded. . As shown in FIG. 7, the opening 13 has a U-shape in which the lens optical axis L side is cut out in plan view (that is, when viewed from the direction of the lens optical axis L). More specifically, the opening 13 has an arc shape (center arc of which is greater than 180 degrees) with a center on the Z axis in plan view. If the opening 13 is formed in a perfect circular shape centered on the Z-axis, a thin and structurally vulnerable portion is formed on the lens optical axis L side. Is preferred. In the present embodiment, the radius of the arc of the opening 13 is designed to be slightly larger than the radius of the drive shaft 56. The adhesive A1 is supplied between the outer peripheral surface of the drive shaft 56 and the inner surface of the opening 13, and the drive shaft 56 and the cap 10 are adhered by the adhesive A1. The adhesive A1, like the opening 13, has a U-shape in plan view.

  The actuator 54 is bonded to the base member 30 at the lower end as shown in FIGS. 6 and 8. Specifically, the opening 31 is provided at the position of the actuator 54 of the base member 30, and the inner surface of the opening 31 and the outer surface of the weight portion 57 of the actuator 54 are bonded. As shown in FIG. 8, the opening 31 has a substantially rectangular shape in plan view (that is, when viewed from the direction of the lens optical axis L). In the present embodiment, the size of the opening 31 is designed to be slightly larger than the size of the weight 57. The adhesive A2 is supplied between the outer peripheral surface of the weight 57 and the inner surface of the opening 31, and the weight 57 and the base member 30 are bonded by the adhesive A2. The adhesive A2 has a rectangular shape in a plan view similarly to the opening 31. The type of the material forming the adhesive A2 may be the same as the type of the material forming the adhesive A2 described above.

  In the lens drive device 1 described above, the upper end of the drive shaft 56 of the actuator 54 is bonded to the cap 10 and the weight 57 is bonded to the base member 30. Therefore, the position and the posture of the actuator 54 are held with high accuracy by the cap 10 and the base member 30. Therefore, the lens driving device 1 can prevent the actuator 54 from being damaged even when an impact is applied, and has high impact resistance.

  In the lens driving device 1, the cap 10 has the opening 13 into which the upper end of the actuator 54 enters, and the actuator 54 adheres to the cap 10 at the outer periphery of the upper end that enters the opening 13 of the cap 10. Have been. When the upper end of the actuator 54 enters the opening 13 of the cap 10, the height of the lower surface of the cap 10 is changed to the height of the upper end of the actuator 54 without the cap 10 abutting on the upper end of the actuator 54. Can be lower. That is, the height of the lens drive device 1 is reduced by lowering the height of the cap 10.

  Further, in the lens driving device 1, the base member 30 has the opening 31 into which the lower end of the actuator 54 enters, and the actuator 54 is provided on the outer periphery of the lower end of the base member 30 that enters the opening 31. 30. When the lower end of the actuator 54 enters the opening 31 of the base member 30, the entire actuator 54 moves downward, thereby further reducing the height of the lens driving device 1.

  In addition, in the lens driving device 1, a part of the outer peripheral wall portion 34 of the base member 30 is located at the same corner as the actuator 54 when viewed from the direction of the lens optical axis L. That is, the outer peripheral wall 34 of the base member 30 and the outer peripheral wall 12 of the cap 10 are abutted and bonded in the vicinity of the actuator 54. The portion where the outer peripheral wall portion 34 of the base member 30 and the outer peripheral wall portion 12 of the cap 10 contact each other functions as a column for reinforcing the actuator 54, and suppresses the situation where the actuator 54 is tilted so as to deviate from the lens optical axis L. be able to. The position where the outer peripheral wall portion 34 of the base member 30 and the outer peripheral wall portion 12 of the cap 10 abut on the lens optical axis L when viewed from the lens optical axis L from the viewpoint of not hindering the movement of the lens frame 40. It is preferable that the position is apart from the actuator 54.

  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.

  DESCRIPTION OF SYMBOLS 1 ... Lens drive device, 10 ... Cap, 12 ... Outer peripheral wall part, 13 ... Opening part, 20 ... Drive main body part, 30 ... Base member, 31 ... Opening part, 34 ... Outer peripheral wall part, 40 ... Lens frame body, 50 ... Friction engagement member, 51 ... leaf spring member, 51a ... tip, 51b ... fixed end, 51c ... connection, 54 ... actuator, 55 ... piezoelectric element, 56 ... drive shaft, 57 ... weight, 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 upper support member that is stacked and adhered on the upper side of the lower support member and accommodates the lens frame between the lower support member,
The outer periphery of the lens frame extends along the optical axis direction of the lens, is extendable and contractible in the optical axis direction of the lens, and has an upper end bonded to the upper support member and a lower end positioned on the lower side. An actuator bonded to the support member;
A first end extending along an outer periphery of the lens frame and frictionally engaged with an outer periphery of the upper end so as 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 upper support member has an opening into which an upper end of the actuator enters,
The lens driving device according to claim 1, wherein the actuator is bonded to the upper support member at an outer periphery of the upper end portion that has entered the opening of the upper support member. The lower support member has an opening into which a lower end of the actuator enters,
3. The lens driving device according to claim 1, wherein the actuator is bonded to the lower support member at an outer periphery of the lower end portion that enters the opening of the lower support member. 4. The lower support member has a rectangular shape as viewed from the optical axis direction of the lens, and has a side wall bonded to the upper support member at one corner,
The lens driving device according to claim 1, wherein the actuator is arranged at a corner where the side wall is provided. 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.

Images