WO2014049961A1

WO2014049961A1 - Actuator unit for driving imaging lens, and imaging device

Info

Publication number: WO2014049961A1
Application number: PCT/JP2013/005092
Authority: WO
Inventors: 松尾　隆; 豊年川崎; 拓真森川
Original assignee: コニカミノルタ株式会社
Priority date: 2012-09-28
Filing date: 2013-08-28
Publication date: 2014-04-03
Also published as: JP5556976B1; JPWO2014049961A1

Abstract

In this actuator unit for driving an imaging lens, and imaging device, an actuator, which is fixed to a unit body, is configured in such a manner as to have: an electro-mechanical conversion element, which converts electrical energy into mechanical energy that expands and contracts; a drive friction member that is fixed to one end of the electro-mechanical conversion element in the expansion/contraction direction, and through which the mechanical energy is transmitted; and a moving body that engages with the drive friction member at a contact surface at a prescribed friction force. The actuator is further configured in such a manner that when the moving body has been moved to an infinite imaging position on an image unit side, the length dimension becomes smaller in the optical axis direction due to part of the aforementioned contact surface being made to protrude on the unit body side more than the drive friction member.

Description

Imaging lens driving actuator unit and imaging apparatus

The present invention relates to an imaging lens driving actuator unit that is suitably used for an imaging device of a mobile phone, for example, and drives an imaging lens, and an imaging device using the same.

Conventionally, Patent Document 1 discloses an actuator unit that drives an imaging lens.

As shown in FIG. 11, the actuator unit includes an actuator 201 and a housing (unit main body) 202, and the image pickup device 203 is disposed on the back side of the unit 200 (the right side in FIG. 11). The imaging lens 204 is moved along the optical axis O.

The actuator 201 includes an actuator main body 205 and a moving body 230, and the actuator main body 205 includes a drive friction member (drive shaft) 210 and an electromechanical conversion element (piezoelectric element) 211. The drive friction member 210 is a cylindrical shaft member that extends in the optical axis direction (the left-right direction in FIG. 11). The electromechanical transducer 211 repeatedly expands and contracts in the optical axis direction (that is, vibrates in the optical axis direction) when electric power having a predetermined waveform is supplied. A driving friction member 210 is connected to one end (left end in FIG. 11) 213 of the electromechanical conversion element 211 in the optical axis direction so that the central axis coincides with the optical axis direction.

The housing 202 has an internal space for housing the actuator body 205. When the electromechanical conversion element 211 expands and contracts, the casing 202 is located inside the casing 202 at the other end (the end opposite to the one end connected to the driving friction member 210: the right end on the paper in FIG. 11) 214. The electromechanical conversion element 211 is held inside so that the position of is not changed. In addition, the housing 202 supports the tip of the actuator body 205 (tip of the driving friction member 210) 215 so as to be able to reciprocate in the optical axis direction. More specifically, the tip 215 of the drive friction member 210 is inserted into a hole 221 provided in the front wall 220 of the housing 202 so as to reciprocate in the optical axis direction. As a result, even if a force is applied in the radial direction (the direction orthogonal to the optical axis direction) to the tip 215 side of the drive friction member 210, the drive friction member 210 is supported by the inner peripheral surface defining the hole 221.

The moving body 230 includes a moving body main body 231 that holds the imaging lens (driven member) 204, and an engaging portion 232 that extends from the moving body main body 231 in a direction orthogonal to the optical axis direction (upward in FIG. 11). . In the moving body 230, the engaging portion 232 is inserted into an opening 222 provided in the housing 202, and moves relative to the housing 202 in the optical axis direction. The engaging portion 232 sandwiches a part of the actuator main body 205 (the driving friction member 210) with a predetermined force. Thereby, the moving body 230 is engaged with the drive friction member 210 by a predetermined frictional force (that is, the moving body 230 and the actuator main body 205 are frictionally engaged).

In such an actuator unit 200, when the electromechanical conversion element 211 vibrates in the optical axis direction (repetitively expands and contracts) when electric power having a predetermined waveform is supplied, the driving friction connected to the electromechanical conversion element 211. The member 210 vibrates (reciprocates) in the optical axis direction. In this case, the movable body 230 moves in the optical axis direction by the engagement portion 232 of the movable body 230 being engaged with the drive friction member 210 with a predetermined frictional force. Thereby, the imaging lens 204 held by the moving body 230 is moved (driven) in the optical axis direction, and the distance between the imaging lens 204 and the imaging element 203 is adjusted (that is, the focus is adjusted).

During this movement, the area of the contact portion between the engaging portion 232 and the drive friction member 210 does not change. That is, in this actuator unit 200, the drive friction member 210 has a length dimension (length dimension in the optical axis direction) larger than the moving range (stroke) in the optical axis direction of the moving body 230 (imaging lens 204). Therefore, the contact area of the engaging portion 232 with the drive friction member 210 is constant regardless of the position of the moving body 230 within the stroke. Thereby, the posture of the moving body 230 with respect to the drive friction member 210 (the casing 202 to which the actuator main body 205 is fixed) at each position in the stroke is stabilized, and the moving body 230 (moving body) when moving in the optical axis direction. Defocusing caused by the inclination of the imaging lens 204) held by 230 is suppressed.

In the actuator unit 200, it is necessary to secure a space in which the actuator 201 (at least the actuator main body 205 having the driving friction member 210) for driving the moving body 230 (imaging lens 204) is disposed. That is, the actuator 201 includes a drive friction member 210 having a length dimension (length dimension in the optical axis direction) larger than the moving range (stroke) in the optical axis direction of the moving body 203 (imaging lens 204). The unit 200 has a length dimension in the optical axis direction in which a space for arranging the actuator 201 can be secured.

In recent years, the actuator unit 200 including such an actuator 201 has been required to have a low profile (smaller length in the optical axis direction).

JP 2007-274777 A

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an imaging lens driving actuator unit capable of reducing the height and an imaging apparatus using the imaging lens driving actuator unit.

In the imaging lens driving actuator unit and the imaging apparatus according to the present invention, the actuator fixed to the unit body includes an electromechanical conversion element that converts electrical energy into mechanical energy that expands and contracts, and one end in the expansion and contraction direction of the electromechanical conversion element. A driving friction member that is fixed to the driving friction member, and a moving body that is engaged with the driving friction member at a contact surface with a predetermined frictional force. When moved to a position, the length of the optical axis direction is reduced by projecting a part of the contact surface from the drive friction member toward the unit main body.

The above and other objects, features and advantages of the present invention will become apparent from the following detailed description and the accompanying drawings.

It is a perspective view of the actuator unit for image pick-up lens drive concerning this embodiment. FIG. 3 is an exploded perspective view of the imaging lens driving actuator unit. It is a perspective view of the unit main body of the imaging lens driving actuator. It is a top view of the said unit main body of the state which has arrange | positioned the actuator main body. It is a top view of the said unit main body of the state which has arrange | positioned the actuator. It is an expansion perspective view of the actuator body. It is a perspective view of a moving body. It is a disassembled perspective view of the said mobile body. It is a schematic diagram for demonstrating the said imaging lens drive actuator unit of the state in which the lens barrel was hold | maintained. It is a figure for demonstrating the remote shooting position of the said mobile body. It is sectional drawing of the conventional actuator unit.

Hereinafter, an embodiment according to the present invention will be described with reference to the drawings. In addition, the structure which attached | subjected the same code | symbol in each figure shows that it is the same structure, The description is abbreviate | omitted suitably. In this specification, when referring generically, it shows with the reference symbol which abbreviate | omitted the suffix, and when referring to an individual structure, it shows with the reference symbol which attached the suffix. FIG. 1 is a perspective view of an imaging lens driving actuator unit according to the present embodiment, and FIG. 2 is an exploded perspective view of the imaging lens driving actuator unit. 3 is a perspective view of the unit main body of the imaging lens driving actuator, FIG. 4 is a plan view of the unit main body in a state where the actuator main body is disposed, and FIG. 5 is a unit main body in a state where the actuator is disposed. FIG. FIG. 6 is an enlarged perspective view of the actuator body.

In the following description, the X direction in FIGS. 1, 2, and 6 to 10 will be described as the upper side, and the Y direction will be described as the lower side. The actuator unit according to the present embodiment is used in an imaging apparatus. In this case, the upper side is the object side, and the lower side is the image side.

The imaging lens driving actuator unit (hereinafter also simply referred to as “actuator unit”) according to the present embodiment is used in a camera module (imaging device) that can be mounted on, for example, a mobile phone. It moves (drives) an imaging lens used for focusing and zooming. As shown in FIGS. 1 and 2, the actuator unit 1 includes a unit main body 2, an actuator 3, and a cover 8.

The unit main body 2 is a base member that holds and supports the actuator 3, and includes, for example, a base 20 and a plurality of (four in the example of the present embodiment) struts (first to

fourth struts

120a and 120b). 120c, 120d). The unit body 2 is formed of a resin material such as LCP (liquid crystal polymer), for example. The unit main body 2 of the present embodiment is formed by injection molding in a form in which electrode terminals (the first electrode terminal 22 and the second electrode terminal 23) are inserted.

As shown in FIGS. 3 to 5, the base portion 20 has a rectangular outline in a plan view and a circular through hole 21 penetrating in the vertical direction in the center portion. The through hole 21 serves as an optical path, and in the following description, an axis that vertically penetrates the center of the through hole 21 is a central axis (optical axis) C.

The base 20 has four corners (first to

fourth corners

20a, 20b, 20c, 20d). In the present embodiment, a specific corner (the lower left corner in FIG. 3) is the first corner 20a, and the second corner 20b and the third corner are counterclockwise in FIG. A portion 20c and a fourth corner 20d are assumed.

The first to

fourth corner portions

20a, 20b, 20c, 20d of the base 20 are provided with first to

fourth support columns

120a, 120b, 120c, 120d. Specifically, the first column 120a extends upward from the first corner 20a, the second column 120b extends upward from the second corner 20b, and the third A third column 120c extends upward from the corner 20c, and a fourth column 120d extends upward from the fourth corner 20d. On each upper end of the first support column 120a, the third support column 120c, and the fourth support column 120d, a mounting table 120e that abuts against the inner side surface (back surface) of the top wall 81 of the cover 8 protrudes. . The second support column 120 b is configured such that the entire upper end surface is in contact with the inner surface of the top wall 81 of the cover 8. The

respective struts

120a, 120b, 120c, and 120d are in contact with the corresponding inner side surfaces of the corners of the cover 8 so that the rigidity (strength) of the casing constituted by the unit main body 2 and the cover 8 is improved. .

The first support column 120a is in contact with the actuator 3 (specifically, the actuator body 30). The first support column 120a includes an outer surface 121a and an inner surface 122a on the surface thereof. In plan view, the outer surface 121a is flush with the outer surface of the first corner 20a of the base 20, and the inner surface 122a is curved along the outer peripheral surface of the actuator body 30 (specifically, the drive shaft 33). The actuator body 30 (specifically, the drive shaft 33) comes into contact.

The outer surface 121a has a shallow groove 123a extending vertically as shown in FIG. The shallow groove 123a is coated with an adhesive when a gap occurs between the outer side surface 121a of the first support column 120a and the peripheral wall 83 (side wall 83a) facing the outer side surface 121a due to a manufacturing error or the like. And used when filling the gap.

The inner side surface 122a is in contact with the actuator main body 30 (drive shaft 33) at a plurality of locations (two locations in the example of the present embodiment). That is, the inner side surface 122a of the present embodiment includes a first column side sliding surface 125a and a second column side sliding surface 126a. In this way, the inner surface 122a contacts the outer peripheral surface of the drive shaft 33 at a plurality of positions at intervals in the circumferential direction, so that the actuator unit moves between the drive shaft 33 and the inner surface 122a when reciprocating (vibrating). It is possible to effectively receive a part of the force applied to the drive shaft 33 and the stress generated in the actuator main body 30 while suppressing the friction between them. That is, when the inner side surface 122a and the driving shaft 33 are in contact with each other at a plurality of positions at intervals in the circumferential direction, the driving is performed in comparison with the case where the entire inner side surface 122a facing the driving shaft 33 is in contact with the driving shaft 33. Friction when the shaft 33 reciprocates (vibrates) is suppressed. In addition, the inner surface 122a and the outer peripheral surface of the drive shaft 33 are in contact with each other at a plurality of intervals in the circumferential direction, thereby improving impact resistance against forces applied to the drive shaft 33 from various directions in the circumferential direction. To do.

The first column side sliding surface 125a is provided at a position substantially opposite to the first moving body side sliding surface 55 of the moving body 4 with the drive shaft 33 interposed therebetween. Further, the second column side sliding surface 126a is provided at a position substantially opposite to the second moving body side sliding surface 62a of the moving body 4 with the drive shaft 33 interposed therebetween. As described above, the column-

side sliding surfaces

125a and 126a are provided at positions substantially opposite to the contact portion between the moving body 4 and the drive shaft 33 with the drive shaft 33 interposed therebetween, so that the drive shaft 33 is connected to the contact portion. When a force is applied from the movable body 4 through the column-

side sliding surfaces

125a, 126a on the substantially opposite side of the drive shaft 33 can effectively receive the applied force, impact resistance is improved.

The second support column 120b is provided on the inner side of the outer surface of the second corner of the base. Specifically, the second column b 120 b is provided between the moving body 5 of the moving body 4 and the guide spring 6. The third support column 120c is formed with a restriction portion groove 29 into which a part of the movable body 4 (specifically, the rotation restriction portion 61a) is fitted so as to be movable up and down. The restriction portion groove 29 is provided on the inner side surface (side surface of the central axis C) 122c of the third support column portion 120c and extends in the vertical direction. Further, the outer surface 121c of the third support column 120c is flush with the outer surface of the third corner portion 20c of the base 20 in plan view. The fourth support column 120d is configured such that the outer surface 121d is flush with the outer surface of the fourth corner 20d of the base 20 and the inner surface 122d is curved along the moving body 4 in plan view. ing.

The side surface of the base 20 has a locking projection 20f for locking the cover 8 to the base 20 (unit main body 2). The locking projections 20f of the present embodiment are provided on a pair of opposing side surfaces of the base portion 20, respectively.

The base portion 20 includes an actuator holding portion 25 that holds the actuator 3 (actuator body 30) on the inner side (center axis C side) of the first support column portion 120a in the first corner portion 20a. The actuator holding portion 25 is recessed in a cylindrical shape so as to have a predetermined depth from the upper surface 20 e of the base portion 20.

Further, the base 20 has the first electrode terminal 22 and the second electrode terminal 23 described above at the first corner 20a. The intermediate portions of the first electrode terminal 22 and the second electrode terminal 23 are embedded in the base 20 (unit body 2). Then, the

distal ends

22a, 23a of the first electrode terminal 22 and the second electrode terminal 23 protrude (expose) with the side surfaces facing each other from both sides of the actuator holding portion 25 on the upper surface 20e, and the base end side is the base portion 20 The

external connection terminals

22b and 23b are configured to protrude (expose) from the outer surface of the external connection terminal. These

external connection terminals

22b and 23b are connected to a circuit board, a connector, and the like of the cellular phone when the actuator unit 1 is mounted on, for example, a cellular phone (not shown). The

external connection terminals

22b and 23b of the present embodiment are bent through stepped portions so that the lower surfaces of the

external connection terminals

22b and 22b are located on the same plane.

The actuator 3 includes an actuator body 30 and a moving body 4. As shown in FIG. 6, the actuator body 30 includes, in order from the bottom, a weight 31, a piezoelectric element (electromechanical conversion element) 32 that can be expanded and contracted (vibrated) in the central axis C direction, and expansion and contraction (vibration) of the piezoelectric element 32. ), And a drive shaft (drive friction member) 33 that reciprocates (vibrates) in the direction of the central axis C. The actuator main body 30 is fixed to the unit main body 2 so that a part (drive shaft 33) of the actuator main body 30 is in contact with the moving body 4 and the first support column 120a (101 and 102 in FIG. 5 and 103 in FIG. 4). , 104).

By increasing the inertial mass on one end side (the lower end side in the present embodiment) of the piezoelectric element 32, the weight 31 preferentially displaces the piezoelectric element 32 due to expansion and contraction on the other end side (the upper end side in the present embodiment). Preferably, it is generated only on the other end side. The weight 31 of the present embodiment is formed of a material having a high specific gravity, such as tungsten or a tungsten alloy. The weight 31 has a disk shape or a columnar shape that protrudes radially outward from the outer periphery of the piezoelectric element 32. Note that the weight 31 is omitted when the other end (lower end) of the piezoelectric element 32 is attached to a device that exhibits a function similar to the function of the weight 31 (for example, the unit main body 2 (base 20)). Also good.

The piezoelectric element 32 is an example of an electromechanical conversion element, and repeats expansion and contraction (vibrates) in the direction of the central axis C when electric power having a predetermined waveform is supplied. The piezoelectric element 32 of the present embodiment is configured by a quadrangular columnar stacked piezoelectric element in which rectangular layers obtained by thinly extending a piezoelectric material are stacked in the direction of the central axis C so that an internal electrode is sandwiched between the layers. Examples of the piezoelectric material include lead zirconate titanate (so-called PZT), crystal, lithium niobate (LiNbO ₃ ), potassium tantalate niobate (K (Ta, Nb) O ₃ ), barium titanate (BaTiO ₃ ), Inorganic piezoelectric materials such as lithium tantalate (LiTaO ₃ ) and strontium titanate (SrTiO ₃ ).

The plurality of internal electrodes include a plurality of anode layers of the plurality of internal electrodes on one side of the outer peripheral side surface of the multilayer piezoelectric element, and a plurality of cathode layers on the other side of the outer peripheral side surface of the multilayer piezoelectric element. Each of the layers is configured to extend to reach the outside with a pair of outer peripheral side surfaces facing each other. A pair of

external electrodes

32a and 32a supply the electric energy to the laminated body, and are formed on the pair of outer peripheral side surfaces of the laminated piezoelectric element by a sputtering method such as silver along the laminating direction. The plurality of internal electrodes between the piezoelectric layers are sequentially and alternately connected to the plurality of internal electrodes so as to be connected in parallel.

The lower end surface of the piezoelectric element 32 is bonded to the upper end surface of the weight 31 with an adhesive such as an epoxy adhesive. In the epoxy adhesive of this embodiment, resinous beads having a diameter of about 5 μm are mixed in order to prevent a short circuit with the weight 31 and stabilize the thickness of the adhesive layer.

The drive shaft 33 is a columnar member extending in the direction of the central axis C. The drive shaft 33 is disposed such that a part of the outer peripheral surface thereof is in contact with the moving body 4 and the first support column 120a (see 101 and 102 in FIG. 5 and 103 and 104 in FIG. 4). That is, the outer peripheral surface of the drive shaft 33 includes a contact surface (contact portion) with the moving body 4 and a contact surface (contact portion) with the first support column 120a. The drive shaft 33 of the present embodiment is made of, for example, carbon fiber reinforced plastic (CFRP, carbon-fiber-reinforced plastic) formed in a columnar shape so that carbon fibers are arranged in the direction of the central axis C. By arranging the carbon fibers in this way, when the drive shaft 33 reciprocates (vibrates) in the direction of the central axis C in sliding contact with the moving body 4 and the first support column 120a, it slides smoothly. The fluffing of the carbon fiber on the surface of the drive shaft 33 (sliding contact portion) can be suppressed.

The drive shaft 33 is formed so as to protrude radially outward from the outer periphery of the piezoelectric element 32. That is, when viewed in the direction of the central axis C, the contour of the piezoelectric element 32 is included in the region surrounded by the contour of the drive shaft 33.

The lower end surface of the drive shaft 33 is bonded to the upper end surface of the piezoelectric element 32 with an adhesive. This adhesive is the same as the adhesive that bonds the weight 31 and the piezoelectric element 32.

When the drive shaft 33 and the piezoelectric element 32 are bonded to each other, the fillet 35 (see FIG. 6) formed by the adhesive protruding from the joint surface between the drive shaft 33 and the piezoelectric element 32 is used. Is formed on the piezoelectric element 32 side because it has a shape that protrudes radially outward from the outer periphery to the entire periphery. That is, the fillet 35 is not formed on the outer peripheral surface of the drive shaft 33. As a result, the entire area of the outer peripheral surface of the drive shaft 33 in the direction of the central axis C can be used for sliding with the movable body 4, and a large stroke (movement range of the movable body 4 in the direction of the central axis C) is achieved by the short drive shaft 33. Can be realized.

The actuator body 30 configured as described above is inserted into the actuator holding portion 25 of the unit body 2 (base portion 20) from the weight 31 side. Then, the bottom surface of the actuator holding portion 25 and the weight 31 are bonded with an adhesive, whereby the actuator main body 30 is fixed to the unit main body 2. At this time, the central axis of the drive shaft 33 of the actuator main body 30 and the central axis C of the unit main body 2 are parallel to each other.

The actuator body 30 is connected to the first electrode terminal 22 and the second electrode terminal 23 by a first electrode coupling spring 26a and a second electrode coupling spring 26b so as to be energized. More specifically, one external electrode 32a of the piezoelectric element 32 and the tip 22a of the first electrode terminal 22 are connected via a first electrode coupling spring 26a so that energization is possible, and the other external electrode 32a of the piezoelectric element 32 is connected. And the tip 23a of the second electrode terminal 23 are connected to each other through a second electrode coupling spring 26b so as to be energized. The first electrode connection spring 26a and the second electrode connection spring 26b are torsion coil springs plated with gold or platinum.

Next, the moving body 4 will be described with reference to FIGS. FIG. 7 is a perspective view of the moving body, and FIG. 8 is an exploded perspective view of the moving body. FIG. 9 is a schematic diagram for explaining the imaging lens driving actuator unit in a state where the lens barrel is held.

The moving body 4 can hold a lens barrel (driven member) 7 (see FIG. 9) and can move relative to the unit body 2 in the direction of the central axis C. More specifically, the moving body 4 includes a metal cylindrical moving body main body (holding portion) 5 and a guide spring 6.

The movable body 5 includes a lens holding portion 54 on the inner peripheral side, and the lens barrel 7 is held by the lens holding portion 54. The lens barrel 7 is a driven member of the actuator unit 1 and holds one or a plurality of lens (imaging lens) groups 71.

The movable body 5 includes a cylindrical portion 51, a first flange 52, and a second flange 53. The mobile body 5 of the present embodiment is formed of a stainless material having a thickness of 0.05 mm to 0.3 mm, for example. Stainless steel is a material that is inexpensive, has good formability, has good durability, and has good driving performance among metal materials. The movable body 5 is formed by, for example, drawing.

Thus, since the cylindrical moving body main body 5 is made of metal, it has high strength and durability against wear. As a result, the cylindrical moving body main body 5 is thinned and held by the moving body main body 5. It is possible to increase the diameter of the lens group 71 (which is held in detail via the lens barrel 7). Furthermore, since the drive shaft 33 directly drives the movable body 5 that holds the lens group 71, the lens group 71 is compared with a configuration in which a portion that is frictionally engaged with the drive shaft 33 is provided separately from a portion that holds the lens group 71. The diameter can be increased.

In the cylindrical part 51, a part of the outer peripheral surface constitutes a first moving body side sliding surface 55 in sliding contact with the drive shaft 33. That is, the cylindrical part 51 (movable body main body 5) includes the first movable body side sliding surface 55 on the outer peripheral surface thereof. The first moving body-side sliding surface 55 of the present embodiment has a part of the moving body main body 5 (more specifically, a predetermined width in the circumferential direction and the center axis C direction) when the moving body main body 5 is molded. It is a plane formed by making it flat.

The first flange 52 protrudes radially inward from the lower end of the cylindrical portion 51. The upper surface of the first flange 52 constitutes a lens barrel mounting portion 52a. In the lens barrel mounting portion 52a, the lens barrel 7 is mounted when the lens holding portion 54 holds the lens barrel 7 (see FIG. 9). As a result, the central axis of the movable body 5 and the optical axis of the lens group 71 of the lens barrel 7 are aligned without tilting each other. Further, the second flange 53 protrudes radially outward from the upper end of the tubular portion 51. The strength of the movable body 5 is ensured by the first flange 52 and the second flange 53.

The guide spring 6 includes an arc portion 61, a guide portion 62 formed on one end side of the arc portion 61, and a pressing piece 63 formed on the other end side of the arc portion 61. The guide spring 6 of the present embodiment is made of, for example, a stainless material having a thickness of 0.1 mm to 0.3 mm.

The arc portion 61 includes a rotation restricting portion 61a at a position separated from the guide portion 62 by approximately 180 ° in the circumferential direction. The rotation restricting portion 61a is a portion for restricting the rotation of the moving body 4 with the drive shaft 33 as the center of rotation. The rotation restricting portion 61a includes a restricting frame portion 61b and a hemispherical protrusion 61c formed on the restricting frame portion 61b.

The regulation frame portion 61b is formed by projecting a part of the arc portion 61 radially outward in a rectangular shape. Further, the protrusion 61c is formed so as to protrude outward from each of both outer side surfaces of the restriction frame portion 61b. The outer width W1 (see FIG. 5) between these protrusions 61c is such that the inner width W2 of the restriction portion groove 29 is such that the restriction frame portion 61b fits within the restriction portion groove 29 provided in the third support column portion 120c. It is set slightly narrower than (see FIG. 5).

The guide part 62 extends radially outward from one end of the arc part 61. One surface (second sliding surface) 62 a of the guide part 62 is approximately 90 ° with respect to the first moving body side sliding surface 55 of the moving body 5 with the guide spring 6 attached to the moving body 5. It has become.

The pressing piece 63 extends linearly from the other end of the arc portion 61. The pressing piece 63 extends linearly from the second support column 120b toward the first support column 120a in a state of being incorporated in the actuator unit 1. The pressing piece 63 includes a pressing portion 63 a that presses the drive shaft 33 at the tip.

The guide spring 6 and the movable body 5 configured as described above are connected by welding. More specifically, the guide spring 6 of the movable body main body 5 is arranged such that the first movable body side sliding surface 55 of the movable body main body 5 and the second movable body side sliding surface 62a of the guide spring 6 are adjacent to each other. It is arranged along the outer periphery. In this state, the guide spring 6 and the movable body 5 are connected by welding a plurality of locations (for example, resistance welding (spot welding), laser welding, etc.).

In this way, the movable body 5 and the guide spring 6 are made of metal and joined together by welding, so that they can be firmly fixed to each other and can be fixed instantaneously unlike adhesion, etc. Tact time can be greatly reduced.

The movable body 4 to which the movable body main body 5 and the guide spring 6 are coupled has the rotation restricting portion 61a fitted in the restriction portion groove 29 of the unit main body 2 (third support column portion 120c), and the first The movable body side sliding surface 55, the second movable body side sliding surface 62a, and the pressing portion 63a are disposed so as to surround the drive shaft 33. In this state, the pressing piece 63 passes through the outside of the second support column 120b of the unit body 2 and extends to the first support column 120a of the first corner portion 20a. At this time, the pressing portion 63a of the pressing piece 63 is in the initial position (the first moving body side sliding surface 55, the second moving body side sliding surface 62a, and the pressing portion 63a do not surround the drive shaft 33). The drive shaft 33 is elastically deformed in a direction away from the outer peripheral surface of the movable body 5 with respect to the position), so that the drive shaft 33 is moved to the first movable body side sliding surface 55 and the second movement by the elastic return force (elastic force). It is in a state of being pressed against the body-side sliding surface 62a. That is, the driving shaft 33 is pressed against the first moving body side sliding surface 55 and the second moving body side sliding surface 62a by the elastic force of the pressing piece 63, and the moving body 4 and the driving shaft 33 are frictionally engaged. ing.

Further, the contact portion between the drive shaft 33 and the first moving body side sliding surface 55 and the second moving body side sliding surface 62 a of the moving body 4, and the rotation restricting portion 61 a and the restricting portion groove 29 of the moving body 4. A lubricant such as oil, grease, or oil mixed with Teflon (registered trademark) flakes is applied to the contact portion. Thereby, the durability improvement of a sliding part and the reliability with respect to adhering at the time of leaving are securable.

Next, returning to FIGS. 1 and 2, the cover 8 will be described.

The cover 8 is a member surrounding the moving body 4 in cooperation with the unit main body 2. The cover 8 includes a top wall 81 and a peripheral wall 83 that hangs down from the periphery of the top wall 81.

The top wall 81 has a rectangular outline in a plan view, and has a through hole 82 penetrating in the central axis C direction at the center thereof. The through hole 82 becomes an optical path. The cover 8 of the present embodiment is formed by drawing, pressing, or the like, for example, a stainless steel thin plate of 0.1 mm to 0.2 mm.

The peripheral wall 83 is constituted by four side walls 83 a corresponding to each piece of the top wall 81. Each side wall 83a includes a locking hole 84 that is locked to a locking projection 20f provided on the side surface of the unit main body 2 (base portion 20). Note that the number of the locking projections 20f in the present embodiment is two, and the locking projections 20f are locked in the locking holes 84 of the opposing side wall 83a.

The first column 120a, the third column 120c, and the fourth column 120d of the unit main body 2 are mounted on the upper ends of the column 120e, the upper column of the second column 120b, and the cover 8 The cover 8 is locked to the unit main body 2 by the locking hole 84 being locked to the locking projection 20f in a state where the inner surface of the top wall 81 is in contact. At this time, the upper end surfaces of the mounting tables 120e and the second support columns 120b and the inner surface of the top wall 81 of the cover 8 are bonded (bonded) with an adhesive.

The actuator unit 1 configured as described above may be used in a camera module (imaging device). Such a camera module includes the above-described actuator unit 1, an imaging device (imaging sensor) that converts an optical image into an electrical signal, and one or a plurality of imaging lenses. An imaging optical system that forms an image on the light receiving surface, and the imaging lens that moves along the optical axis direction of the one or more imaging lenses in the imaging optical system is attached to the moving body 4 of the actuator unit 1 It is done. For example, as shown in FIG. 9, a sensor substrate that holds the lens barrel 7 by the lens holding portion 54 of the moving body 4 and has an IR cut filter 102 and an image sensor (image sensor) 103 on the lower surface side of the unit body 2. 104 is arranged. More specifically, the lens barrel 7 is bonded and fixed to the lens holding portion 54 by the adhesive 73 filled in the bonding groove 72 provided in the lens barrel 7. Thereby, a camera module (imaging device) is configured.

Then, for example, the camera module is carried in such a manner that the external connection terminal 22b of the first electrode terminal 22 and the external connection terminal 23b (see FIG. 1 etc.) of the second electrode terminal 23 are placed on the circuit board of the mobile phone. Installed in the phone casing.

When electric power having a predetermined waveform is supplied from the drive circuit to the external connection terminal 22b of the first electrode terminal 22 and the external connection terminal 23b of the second electrode terminal 23, the piezoelectric element 32 of the actuator body 30 moves in the direction of the central axis C. Vibrate (repeat expansion and contraction). The drive shaft 33 reciprocates due to the vibration of the piezoelectric element 32, and the movable body 4 moves in the axial direction (center axis C direction) of the drive shaft 33 due to the reciprocation. More details are as follows.

When a rectangular wave having a predetermined duty ratio is applied to the piezoelectric element 32, the displacement of the piezoelectric element 32 becomes a triangular wave. By changing the duty ratio of the rectangular wave, the slope (speed) is increased and decreased when the amplitude is increased. ) Different triangular waves are generated. The drive mechanism of the actuator 3 utilizes this.

More specifically, a case will be described in which the moving body 4 moves from the short-distance shooting position to the infinite shooting position. FIG. 10 is a diagram for explaining the shooting position of the moving body 4, FIG. 10A is a diagram for explaining the short-distance shooting position of the moving body 4, and FIG. 10B is an infinite shooting of the moving body 4. It is a figure for demonstrating a position. Here, the short-distance shooting position is a position (object side end position) farthest from the base 20 (imaging sensor 103) in the movement range in the central axis C direction of the moving body 4, as shown in FIG. 10A. As shown in FIG. 10B, the infinite photographing position is a position (image side end position) that is closest to the base 20 (imaging sensor 103) in the moving range.

First, when the drive shaft 33 is slowly moved downward by the contraction of the piezoelectric element 32, the moving body 4 frictionally engaged with the drive shaft 33 also moves in the same direction (downward as the drive shaft 33 moves downward). ) Then, when the drive shaft 33 is moved upward by the instantaneous extension of the piezoelectric element 32 so as to exceed the frictional friction force, the movable body 4 is left at that position (the position after the downward movement). . By repeating such reciprocation of the drive shaft 33 in the direction of the central axis C, the moving body 4 moves downward.

When the reciprocating motion of the drive shaft 33 is repeated and the movable body 4 continues to move downward, the contact surface of the movable body 4 that is in contact with the drive shaft 33 (the first movable body-side sliding surface 55 and the second movable surface 50). The lower end of the moving body side sliding surface 62a) protrudes (protrudes) from the drive shaft 33 toward the unit main body. That is, the lower end of the moving body 4 protrudes below the lower end of the outer peripheral surface of the drive shaft 33 (the surface in sliding contact with the first moving body side sliding surface 55 and the second moving body side sliding surface 62a).

In the actuator unit 1 of the present embodiment, the length dimension of the drive shaft 33 in the central axis C direction is suppressed (reduced), and the unit 1 is reduced in height (the length dimension in the central axis C direction). This is because the size is reduced. More specifically, when the moving body 4 is moved to the infinite photographing position, more specifically, the lower part of the moving body 4 (more specifically, the first moving body side sliding surface 55 and the second moving body side sliding surface 62a) ( By adopting a configuration in which a part) is protruded from the lower end of the drive shaft 33 toward the unit main body 2, the contact surface (the first moving body side sliding surface 55) regardless of the position of the moving body 4 in the central axis C direction. Compared with the configuration in which the entire center axis C direction of the second moving body side sliding surface 62a) is in contact with the drive shaft 33, the lower portion of each sliding

surface

55, 62a is driven to the unit body 2 side. The length dimension of the shaft 33 in the direction of the central axis C can be reduced. Thereby, the length dimension in the central axis C direction of the actuator 3 including the drive shaft 33 can be reduced, and as a result, the length in the central axis C direction of the unit (actuator unit) 1 in which the actuator 3 is arranged. It becomes possible to reduce the size (lower profile).

In this case, when the length dimension (refer to α1 and α2 in FIGS. 10A and 10B) of the contact portion between the drive shaft 33 and the moving body

side sliding surfaces

55 and 62a in the central axis C direction is small, The moving body 4 is slightly inclined (that is, the optical axis of the lens group 71 held by the moving body 4 is slightly inclined with respect to the unit body 2 to which the actuator body 30 including the drive shaft 33 is fixed). Since the moving body 4 (lens group 71) appears to be deeply focused at the infinite photographing position, the imaging sensor 103 is used even when the length of the contact portion at the infinite position is shortened. The deterioration of the image quality of the image obtained by the above can be suppressed. On the other hand, when the moving body 4 (lens group 71) is at a short-distance shooting position where the depth of field is shallow, the length of the contact portion in the direction of the central axis C is sufficiently secured. 4 (that is, the inclination of the optical axis of the lens group 71 with respect to the unit main body 2) is suppressed, and the image quality of the image obtained by the imaging sensor 103 is ensured.

In addition, since the outer periphery of the drive shaft 33 protrudes radially outward from the outer periphery of the piezoelectric element 32, it moves when the moving body 4 moves from the short-distance shooting position toward the infinite shooting position. Even if the lower part of the first moving body side sliding surface 55 and the second moving body side sliding surface 62a of the body 4 (the lower part of the cylindrical moving body 4) protrudes from the drive shaft 33 toward the unit body 2 side, the piezoelectric element 32. Do not contact with. That is, the piezoelectric element 32 does not disturb the movement of the moving body 4 in the direction of the central axis C.

Next, the case where the moving body 4 moves from the infinite shooting position to the short distance shooting position will be described. In this case, an operation opposite to the operation in which the moving body 4 moves downward is performed.

More specifically, the drive shaft 33 is slowly moved upward by the extension of the piezoelectric element 32, thereby moving the moving body 4 frictionally engaged with the drive shaft 33 upward. The drive shaft 33 is moved downward by the instantaneous contraction of the piezoelectric element 32 so as to exceed the frictionally engaged frictional force, so that the moving body 4 is left at that position (the position after the upward movement). To. By repeating such reciprocation of the drive shaft 33 in the direction of the central axis C, the moving body 4 moves upward.

It should be noted that the imaging lens driving actuator unit of the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the present invention.

In the imaging lens driving actuator unit 1 of the above embodiment, the lens barrel 7 that holds the lens group 71 is held by the moving body 4 that is driven by the actuator body 30 (drive shaft 33). It is not limited. For example, the movable body itself may hold one or a plurality of imaging lenses, and the actuator main body 30 (drive shaft 33) may drive the movable body that directly holds the imaging lenses.

In the imaging lens driving actuator unit 1 of the above embodiment, the drive shaft 33 is slid on the first moving body side sliding surface 55 and the second moving body side sliding surface by the elastic restoring force (elastic force) of the pressing piece 63 of the guide spring 6. Although the movable body 4 and the drive shaft 33 are frictionally engaged by being pressed against the surface 62a, it is not limited to this configuration. For example, the drive shaft may be configured by a magnet, and the moving body (specifically, the first sliding surface 55 and the second sliding surface 62a) may be configured by metal. That is, the force that presses the outer peripheral surface of the drive shaft against the first sliding surface 55 and the second sliding surface 62a so as to generate a predetermined frictional force is not limited to an urging force such as an elastic force but is a magnetic force or the like. Also good.

This specification discloses various modes of technology as described above, and the main technologies are summarized below.

An imaging lens driving actuator unit according to an aspect is an imaging lens driving actuator unit that moves an imaging lens with respect to an imaging element, and extends and contracts with a unit main body that is disposed closer to the imaging element than the imaging lens. An electromechanical transducer that converts electrical energy into mechanical energy, a drive friction member that is fixed to one end of the electromechanical transducer in the direction of expansion and contraction and that transmits the mechanical energy, and a predetermined friction force applied to the drive friction member An actuator having a movable body to be engaged, and the movable body includes a contact surface with which the drive friction member comes into contact, can hold the imaging lens, and light of the imaging lens with respect to the unit body The actuator is relatively movable in the axial direction, and the actuator is fixed to the unit main body, Compared with the length dimension in the optical axis direction of the contact portion between the drive friction member and the contact surface when the moving body is moved to the short-distance photographing position farthest from the unit main body, the movable body is photographed in the short-distance photographing. When the position is moved to an infinite photographing position on the unit main body side relative to the position, a part of the contact surface protrudes from the driving friction member to the unit main body side, whereby the length dimension in the optical axis direction of the contact portion is increased. Configured to be smaller.

In such an imaging lens driving actuator unit, when the moving body is moved to the infinite photographing position, a part of the moving body (contact surface) protrudes from the driving friction member toward the unit main body, thereby moving the moving body. The length dimension of the drive friction member in the optical axis direction can be made smaller than the configuration in which the entire optical axis direction of the contact surface contacts the drive friction member regardless of the position of the body in the optical axis direction. Thereby, the length dimension in the optical axis direction of the actuator provided with the drive friction member can be reduced, and as a result, the length dimension in the optical axis direction in the imaging lens driving actuator unit in which the actuator is arranged is reduced. (Shortness and height reduction) can be achieved.

In this case, when the length dimension in the optical axis direction of the contact portion is reduced, the moving body is slightly inclined with respect to the driving friction member (that is, the moving body is held by the moving body with respect to the unit main body to which the actuator is fixed). The optical axis of the imaging lens is slightly inclined), but the moving object (imaging lens) appears to be in focus at a depth of field at the infinite shooting position, so contact at the infinite position as in the above configuration. Even if the length dimension of the part is shortened, it is possible to suppress the deterioration of the image quality of the image obtained by the image sensor. On the other hand, in the above configuration, when the moving body (imaging lens) is at a short-distance shooting position where the depth of field is shallow, a sufficient length dimension in the optical axis direction at the contact portion is ensured. The inclination of the moving body (that is, the inclination of the optical axis of the imaging lens with respect to the unit main body to which the actuator is attached) is suppressed, and the image quality of the image obtained by the imaging element is ensured.

In another aspect, in the above-described imaging lens driving actuator unit, preferably, the electromechanical conversion element is connected to a unit body side end of the driving friction member, and the driving friction member is at least the contact surface. The part which contacts with may have the shape which protruded in the said mobile body side from the said electromechanical conversion element.

In such an imaging lens driving actuator unit, at least a portion of the driving friction member that contacts the contact surface of the moving body protrudes toward the moving body from the electromechanical conversion element, so the moving body has moved toward the infinite photographing position. In this case, even if a part of the contact surface protrudes from the drive friction member toward the unit main body, it does not come into contact with the electromechanical conversion. That is, the electromechanical transducer does not interfere with the movement of the moving body in the optical axis direction.

In another aspect, in the above-described imaging lens driving actuator unit, preferably, the moving body includes a metal cylindrical holding portion that surrounds the imaging lens from the outside in the radial direction, and the holding portion May include the contact surface on its outer peripheral surface.

In such an imaging lens driving actuator unit, since the cylindrical holding portion is made of metal, it has high durability and durability against wear, so that the cylindrical holding portion is thinned and held by the holding portion. Therefore, it is possible to increase the diameter of the imaging lens. Furthermore, since the drive friction member directly drives the holding unit that holds the imaging lens, the diameter of the imaging lens is increased compared to a configuration in which a portion that is frictionally engaged with the drive friction member is provided separately from the portion that holds the imaging lens. Can be achieved.

An imaging apparatus according to another aspect includes any of the above-described imaging lens driving actuator units, an imaging element that converts an optical image into an electrical signal, and one or a plurality of imaging lenses. An imaging optical system that forms an optical image on the light receiving surface of the imaging device, and the imaging lens that moves along the optical axis direction of the one or the plurality of imaging lenses in the imaging optical system, It is attached to the moving body of the actuator unit for driving the imaging lens.

Since such an imaging apparatus includes any one of the above-described imaging lens driving actuator units, it is possible to achieve a reduction in height and size.

This application is based on Japanese Patent Application No. 2012-215679 filed on September 28, 2012, the contents of which are included in the present application.

In order to express the present invention, the present invention has been properly and fully described through the embodiments with reference to the drawings. However, those skilled in the art can easily change and / or improve the above-described embodiments. It should be recognized that this is possible. Therefore, unless the modifications or improvements implemented by those skilled in the art are at a level that departs from the scope of the claims recited in the claims, the modifications or improvements are not covered by the claims. To be construed as inclusive.

According to the present invention, an actuator unit for driving an imaging lens and an imaging device can be provided.

Claims

An imaging lens driving actuator unit for moving an imaging lens with respect to an imaging element,
A unit body disposed on the image sensor side from the imaging lens;
An electromechanical conversion element that converts electrical energy into expanding and contracting mechanical energy, a driving friction member that is fixed to one end in the expansion and contraction direction of the electromechanical conversion element and that transmits the mechanical energy, and a predetermined amount applied to the driving friction member An actuator having a moving body engaged by a frictional force,
The moving body includes a contact surface with which the driving friction member comes into contact, can hold the imaging lens, and can move relative to the unit body in the optical axis direction of the imaging lens,
The actuator is fixed to the unit main body, and a length of the contact portion between the drive friction member and the contact surface in the optical axis direction when the movable body is moved to a short-distance photographing position farthest from the unit main body. When the moving body is moved to the infinite photographing position on the unit main body side rather than the short-distance photographing position, a part of the contact surface is protruded from the driving friction member to the unit main body side as compared with the length dimension. The length of the contact portion in the optical axis direction is configured to be small.
An imaging lens drive actuator unit.
The electromechanical conversion element is connected to a unit main body side end of the drive friction member,
The drive friction member has a shape in which at least a portion in contact with the contact surface protrudes toward the movable body from the electromechanical conversion element.
The actuator unit for driving an imaging lens according to claim 1.
The moving body has a metal cylindrical holding portion that surrounds the imaging lens from the outside in the radial direction,
The holding portion includes the contact surface on an outer peripheral surface thereof,
The actuator unit for driving an imaging lens according to claim 1 or 2.
The imaging lens driving actuator unit according to any one of claims 1 to 3,
An image sensor that converts an optical image into an electrical signal;
An imaging optical system that includes one or a plurality of imaging lenses, and that forms an optical image of an object on a light receiving surface of the imaging element;
The imaging lens that moves along the optical axis direction among the one or more imaging lenses in the imaging optical system is attached to the moving body of the imaging lens driving actuator unit.
Imaging device.