JP2011002811A - Lens driving device, method for setting inside and sma assembly - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make attachment loads on a shape memory alloy wire readily adjustable.SOLUTION: A lens driving device (10) includes a lens holder (18) including a cylindrical part (182) which movably supports a lens barrel (11); housings (14;16) which supports the lens holder (18), only in a direction of the optical axis (O); a moving means for moving the lens holder (18) in the direction of the optical axis(O); and a guiding means for movably guiding the lens holder (18), only in the direction of the optical axis (O). The moving means includes the linear-shaped memory alloy wire (28) stretched between the lens holder (18) and the housing (14;16). Both end parts of the shape memory alloy wire (18) are set inside a pair of pipe-like electrodes (30).

Description

  The present invention relates to a lens driving device, and more particularly to a lens driving device using a shape memory alloy wire as an actuator, a method for inserting a shape memory alloy wire, and an SMA assembly used in the lens driving device.

  As a camera autofocus actuator and zoom actuator, a linear actuator using a shape memory alloy (SMA) (drive device) is known.

  For example, WO2007 / 113478A1 (Patent Document 1) discloses a camera lens driving device that drives the movement of one camera lens supported by one support structure (housing) by one suspension system. The camera lens driving device disclosed in Patent Document 1 mounts a subassembly having an SMA wire connected to at least one mounting member mounted on a support structure. At least two SMA wires are held with tension between the camera lens element and the support structure (housing), each at an acute angle with respect to the optical axis to which tension is applied having a component along the optical axis. The two SMA wires are held at an angle when viewed along the optical axis. The subassembly has a mounting member that connects the SMA wires by caulking. The mounting member is electrically connected to the SMA wire. Thus, the attachment member acts as an electrode. The attachment member (electrode) is composed of an elongated metal piece, and is electrically connected to the end of the SMA wire by caulking the tip.

  Japanese Patent Laying-Open No. 2007-292864 (Patent Document 2) discloses a lens driving device that improves transmission efficiency and is compact. The lens driving device disclosed in Patent Document 2 includes a fixed barrel (housing), a lens frame (lens holder) that holds a part or all of a lens group (lens barrel) constituting an optical system, and a fixed mirror. Guide means for supporting the lens frame (lens holder) movably in the optical axis direction with respect to the tube, and biasing means for biasing the lens frame toward one side in the optical axis direction. The lens driving device moves the lens frame toward the other side against the bias of the biasing means with respect to the fixed barrel.

  The lens driving device disclosed in Patent Document 2 includes a shape memory alloy (SMA) wire and a wire bearing member. Both ends of the SMA wire are fixed to the fixed lens barrel, and when heated by energization, the SMA wire is contracted from a predetermined length of a relaxed state. The shape memory alloy wire returns to its relaxed length when it is cooled by stopping energization. The wire bearing member is provided on the lens frame, and an action portion set between both ends of the shape memory alloy wire is hooked so that the convex direction is in a curved direction facing the one side.

  In the embodiment of the lens driving device disclosed in Patent Document 2, both ends of the SMA wire are fixed to a pair of wire support members, and the pair of wire support members are fixed to a fixed barrel (housing). The energization control unit energizes both ends of the SMA wire via the pair of wire support members. Therefore, the wire support member acts as an electrode. The wire support member (electrode) is formed of an elongated metal piece, like the mounting member (electrode) in Patent Document 1.

  Furthermore, Japanese Patent Application Laid-Open No. 2007-78954 (Patent Document 3) discloses a lens barrel configured to move an imaging lens in the optical axis direction using a shape memory alloy. The lens barrel disclosed in Patent Document 3 has an imaging lens (lens barrel) that forms an image of subject light, and a lens frame (lens holder) that holds the imaging lens (lens barrel), and has a string shape. The imaging lens is moved in a predetermined direction using the formed shape memory alloy. A part of the shape memory alloy is disposed in the optical path of the imaging lens (lens barrel), and the shape memory alloy is contracted by energization to move the lens frame (lens holder). Patent Document 3 also discloses an embodiment of a lens barrel in which a pair of leaf springs of diaphragm time are provided at both ends in the optical axis direction of a lens frame (lens holder).

  In the embodiment of the lens barrel disclosed in Patent Document 3, both end portions of the shape memory alloy formed in a string shape are sandwiched and fixed by a pair of plate members to a columnar portion (housing) erected from the ground plate. ing. The shape memory alloy is energized through the plate member. Therefore, the plate member functions as an electrode.

  Japanese Patent Laying-Open No. 2009-19507 (Patent Document 4) discloses a drive module and an assembling method thereof that can reduce variations in assembling accuracy while improving manufacturing efficiency. The drive module disclosed in Patent Document 3 is a shape memory alloy (SMA) wire in which a driven body (lens holder) movably provided on a chassis (housing; support body) expands and contracts in accordance with the amount of energization. It is locked to the middle part. The drive module includes a pair of holding terminals, and the chassis (housing; support) includes a positioning portion and a locking portion. Each holding terminal has a wire holding portion that holds the end portion of the SMA wire so as to be conductive, a positioned portion with respect to the support, and a locked portion that receives a reaction force from the support toward the positioned portion. . A positioning part latches the to-be-positioned part of a holding terminal. The locking portion locks the locked portion of the holding terminal in the pressed state toward the positioned portion side. Since the holding terminal is an energizing portion, it functions as an electrode. The holding terminal (electrode) is made of a key-shaped plate member, and the end portion of the SMA wire is caulked with a wire holding portion.

WO2007 / 113478A1 JP 2007-292864 A JP 2007-78954 A JP 2009-19507 A

  Patent Documents 1 to 4 described above have problems as described below.

  In the camera lens driving device disclosed in Patent Document 1, an elongated metal piece is used as an attachment member (electrode) for a shape memory alloy wire. Therefore, it is very difficult to adjust the mounting load applied to the shape memory alloy wire.

  Also in the lens driving device disclosed in Patent Document 2, elongated metal pieces are used as a pair of wire support members (electrodes) for SMA wires. For this reason, it is very difficult to adjust the mounting load applied to the SMA wire.

  The lens barrel disclosed in Patent Document 3 also uses a pair of plate members as electrodes. Therefore, it becomes very difficult to adjust the mounting load applied to the string-shaped shape memory alloy.

  The drive module disclosed in Patent Document 4 also uses a key-shaped plate-like member as a pair of holding terminals (electrodes) for SMA wires. For this reason, it is very difficult to adjust the mounting load applied to the SMA wire.

  In the lens driving device, setting the mounting load applied to the shape memory alloy wire is a very important matter from the viewpoint of the amount of contraction of the shape memory alloy member, the amount of displacement (stroke) of the lens, durability, and the like.

  Accordingly, an object of the present invention is to provide a lens driving device, a method for inserting a shape memory alloy wire, and an SMA assembly used in the lens driving device capable of easily adjusting the mounting load applied to the shape memory alloy wire. It is to provide.

  Other objects of the invention will become apparent as the description proceeds.

  According to the first aspect of the present invention, the lens holder (18) including the cylindrical portion (182) that holds the lens barrel (11), and the lens holder (18) can be moved only in the optical axis (O) direction. A housing (12) that supports the lens holder, a moving means for moving the lens holder (18) in the direction of the optical axis (O), and a guide means for guiding the lens holder (18) so as to be movable only in the direction of the optical axis (O). , The moving means includes a linear shape memory alloy wire (28) stretched between the lens holder (18) and the housing (12). Both ends of the shape memory alloy wire (18) are inserted into a pair of pipe-shaped electrodes (30) to obtain a lens driving device.

  In the lens driving device (10; 10A) according to the first aspect of the present invention, the lens holder (18) protrudes radially outward from the cylindrical portion (182), and is an intermediate portion of the shape memory alloy wire (28). It is preferable to have a latching protrusion (184) for latching (28a). Each of the pair of pipe-shaped electrodes (30) includes a main cylindrical portion (302) held in the housing (12) and extending in parallel with the optical axis (O) direction, and the main cylindrical portion (302). It is desirable to be comprised from the front-end | tip cylindrical part (304) bent toward the latching protrusion (184) from the front-end | tip. The pair of pipe electrodes (30) preferably have crimped portions (302a) that are electrically connected to both ends of the shape memory alloy wire (28) at the tail ends of the main cylindrical portion (302). . The caulking portion (302aB) preferably has an uneven inner peripheral surface (302aB ') that prevents the shape memory alloy wire (28) from slipping out.

  In the lens driving device (10A) according to the first aspect of the present invention, a specific resin is injected into the pair of pipe-shaped electrodes (30) from the tail end of the main cylindrical portion (302). It is preferable. The specific resin may be, for example, a conductive resin such as a silver paste, or may be an attachment reinforcing resin for the shape memory alloy wire (28).

  Further, in the lens driving device (10; 10A) according to the first aspect of the present invention, the guide means includes an elastic member (20) disposed between the lens holder (18) and the housing (12). Good. In this case, the elastic member (20) supports the lens holder (18) so as to be displaceable only in the optical axis (O) direction with the lens holder (18) positioned in the radial direction. The elastic member (20) includes, for example, an upper leaf spring (22) and a lower leaf spring (24) provided on the upper and lower sides in the optical axis (O) direction of the cylindrical portion (182) of the lens holder (18), respectively. ). The upper leaf spring (22) includes, for example, an upper ring portion (222) attached to the upper end portion of the lens holder (18), four upper end portions (224) attached to the housing (12), and an upper ring portion. You may comprise from the four upper arm parts (226) which connect each of the four upper edge parts. The lower leaf spring (24) includes a lower inner ring portion (242) attached to the lower end portion of the lens holder (18), a lower outer ring portion (244) attached to the housing (12), and a lower inner ring. And a plurality of lower arm portions (246) connecting the lower outer ring portion.

  According to a second aspect of the present invention, there is provided a method for inserting both ends of a shape memory alloy wire (18) into a pair of pipe-shaped electrodes (30) in the lens driving device, wherein the shape memory alloy wire (18 ) From the tail end of one pipe-shaped electrode (30L) to the tail end of the other pipe-shaped electrode (30R) with a part protruding from the tail end of the other pipe-shaped electrode (30R) Forming a crimped portion (302a) by caulking the one pipe-shaped electrode (30L) and the shape memory alloy wire (28) at the tail end of one pipe-shaped electrode (30L); By grasping a part of the shape memory alloy wire (28) protruding from the tail end of the pipe-shaped electrode (30R) and moving the shape memory alloy wire (28) along the protruding direction, the shape memory alloy wire ( 28) Installation The caulking portion (302a) is obtained by caulking the other pipe-shaped electrode (30R) and the shape memory alloy wire (28) at the tail end portion of the other pipe-shaped electrode (30R) after adjusting the load and after adjusting the load. And a step of forming the charging method.

  In the charging method according to the second aspect of the present invention, the caulking portion (302aB) preferably has an uneven inner peripheral surface (302aB ') that prevents the shape memory alloy wire (28) from coming out. A step of cutting a part of the shape memory alloy wire (28) protruding from the tail end of the other pipe-shaped electrode (30R) may be further included. It is preferable to further include a step of injecting a specific resin into the inside from the tail ends of the pair of pipe-shaped electrodes (30). The specific resin may be, for example, a conductive resin made of silver paste or the like, or may be an attachment reinforcing resin for the shape memory alloy wire (18).

  According to the third aspect of the present invention, there is provided an SMA assembly (32) composed of a linear shape memory alloy wire (28) and a pair of electrodes attached to both ends of the shape memory alloy wire. Thus, the pair of electrodes is composed of a pair of pipe-like electrodes (30) into which both ends of the shape memory alloy wire (28) are inserted, thereby obtaining an SMA assembly.

  In the SMA assembly (32) according to the third aspect of the present invention, the pair of pipe electrodes (30) includes a pair of main cylindrical portions (302) extending in parallel to each other and the pair of main cylindrical portions. It is preferable that it is comprised from a pair of front-end | tip cylindrical part (304) bent at an acute angle toward the mutually adjacent side from the front-end | tip of this.

  The reference numerals in the parentheses are given for ease of understanding, and are merely examples, and of course are not limited thereto.

  In the present invention, the moving means for moving the lens holder in the optical axis direction includes a linear shape memory alloy wire stretched between the lens holder and the housing, and both ends of the shape memory alloy wire are paired with each other. Therefore, the mounting load on the shape memory alloy wire can be easily adjusted.

It is the perspective view which looked at the external appearance of the lens drive device by the 1st Embodiment of this invention from diagonally forward upper direction. FIG. 2 is a perspective view of the lens driving device shown in FIG. FIG. 3 is a perspective view of the lens driving device shown in FIG. 2 as viewed from diagonally forward and with the outer upper cover omitted. It is the disassembled perspective view which looked at the lens drive device shown in FIG. 2 from diagonally forward upper direction. FIG. 4 is a front view of the lens driving device shown in FIG. 3. It is a perspective view which shows the external appearance of the pipe-shaped electrode used for the lens drive device shown in FIG. FIG. 6 is a front view of the lens driving device in a state where an upper cover is omitted in order to explain the flow of a charging process in which both ends of the shape memory alloy wire are charged into a pair of pipe electrodes. (A) is sectional drawing which shows the state before caulking a pipe-shaped electrode to a shape memory alloy wire, (B) is sectional drawing which shows the state after caulking a pipe-shaped electrode to a shape memory alloy wire. It is a front view which shows the lens drive device by the 2nd Embodiment of this invention in the state which excluded the lens barrel and the upper cover. It is the perspective view seen from diagonally forward upper direction, omitting the lens barrel and the outer upper cover from the lens driving device according to the third embodiment of the present invention. It is explanatory drawing which shows typically the state before crimping a pipe-shaped electrode to a shape memory alloy wire. It is explanatory drawing which shows typically the state after crimping a pipe-shaped electrode to a shape memory alloy wire.

  Embodiments of the present invention will be described below with reference to the drawings.

  A lens driving device 10 according to a first embodiment of the present invention will be described with reference to FIGS. 1 to 5. FIG. 1 is a perspective view of the external appearance of the lens driving device 10 as viewed obliquely from above and front. FIG. 2 is a perspective view of the lens driving device 10 as viewed obliquely from above and in a state where the lens barrel 11 is omitted. FIG. 3 is a perspective view of the lens driving device 10 as viewed obliquely from above and in a state where the lens barrel 11 and the upper cover 16 are omitted. FIG. 4 is an exploded perspective view of the lens driving device 10 as viewed obliquely from above and in a state where the lens barrel 11 is omitted. FIG. 5 is a front view showing the lens driving device 10 with the lens barrel 11 and the upper cover 16 omitted.

  Here, as shown in FIGS. 1 to 5, an orthogonal coordinate system (X, Y, Z) is used. 1 to 5, in the orthogonal coordinate system (X, Y, Z), the X-axis direction is the front-rear direction (depth direction), the Y-axis direction is the left-right direction (width direction), and Z The axial direction is the vertical direction (height direction). In the example shown in FIGS. 1 to 5, the vertical direction Z is the direction of the optical axis O of the lens. In the present specification, the forward direction is also referred to as the first side, and the backward direction is also referred to as the second side.

  However, in the actual use situation, the optical axis O direction, that is, the Z-axis direction is the front-rear direction. In other words, the upward direction of the Z axis is the forward direction, and the downward direction of the Z axis is the backward direction.

  The illustrated lens driving device 10 has a plane-symmetric structure with respect to a plane that passes through the optical axis O and is defined by (extends in) the front-rear direction X and the vertical direction Z.

  The illustrated lens driving device 10 is provided in a camera-equipped mobile phone capable of autofocusing, for example. The lens driving device 10 includes a lens barrel (lens assembly) 11 that incorporates an autofocus lens AFL that is a movable lens. The lens driving device 10 is for moving the lens barrel 11 only in the optical axis O direction.

  As shown in FIG. 1, the lens driving device 10 includes a substantially rectangular parallelepiped housing (housing) 12 that covers a lens barrel 11. In other words, the lens barrel 11 is arranged in the housing (housing) 12. The housing (housing) 12 includes an actuator base 14 and an upper cover 16.

  On the other hand, although not shown, an image sensor arranged on the substrate is mounted at the center of the actuator base 14. This imaging device captures a subject image formed by the movable lens AFL and converts it into an electrical signal. The imaging device is configured by, for example, a CCD (charge coupled device) type image sensor, a CMOS (complementary metal oxide semiconductor) type image sensor, or the like.

  The lens driving device 10 includes a lens holder 18 that holds the lens barrel 11. In other words, the lens barrel 11 is held and fixed in the lens holder 18. More specifically, the lens holder 18 includes a cylindrical portion 182 having a substantially cylindrical shape. A female screw (not shown) is cut on the inner peripheral wall of the cylindrical portion 182 of the lens holder 18. On the other hand, a male screw (shown) that is screwed into the female screw is cut on the outer peripheral wall of the lens barrel 11. Therefore, in order to attach the lens barrel 11 to the lens holder 18, the lens barrel 11 is rotated around the optical axis O with respect to the lens holder 18 and screwed along the optical axis O direction. It is accommodated in the lens holder 18 and joined together by an adhesive or the like.

  The lens holder 18 is supported in the housing 12 so as to be movable only in the direction of the optical axis O, as will be described later. The lens movable portion (11, 18) is configured by a combination of the lens barrel 11 and the lens holder 18.

  An outer peripheral wall of the cylindrical portion 182 of the lens holder 18 has a protruding portion 184 that protrudes radially outward in front of the front-rear direction X. The protruding portion 184 protrudes along the vertical direction Z from the tubular portion 182 toward the lower end. The protruding portion 184 is for hooking an intermediate portion 28a of a shape memory alloy wire 28 formed in a linear shape to be described later. Therefore, the protrusion 184 is also called a latching protrusion.

  The actuator base 14 includes a ring-shaped base portion 142, a pair of base front projecting portions 144 projecting upward in the vertical direction Z at two front corners of the base portion 142, and upper and lower portions at two rear corners of the base portion 142. A pair of base rear projecting portions 146 projecting upward in the direction Z. Each of the pair of base front protrusions 144 has a pair of base front protrusions 144a protruding upward. Each of the pair of base rear protrusions 146 has a pair of base rear protrusions 146a that protrude upward. Each of the pair of base front protrusions 144 has a pair of engagement grooves 144b for engaging and holding a pair of pipe electrodes 32 described later. The pair of engagement grooves 144b are formed to extend in the up-down direction Z on the front surfaces of the pair of base front protrusions 144. Furthermore, each of the pair of base front protrusions 144 has a pair of positioning recesses 144c for positioning and holding a pair of pipe electrodes 30 described later.

  The lens driving device 10 includes an upper leaf spring 22 and a lower leaf spring 24 provided respectively on the upper side and the lower side of the cylindrical portion 182 of the lens holder 18 in the optical axis O direction. The upper plate spring 22 and the lower plate spring 24 are arranged between the lens holder 18 and the housing 12 and support the elastic member 20 so as to be displaceable in the optical axis O direction with the lens holder 18 positioned in the radial direction. Work as.

  Further, as described above, in the actual use situation, the upward direction in the Z-axis direction (optical axis O direction) is the forward direction, and the downward direction in the Z-axis direction (optical axis O direction) is the backward direction. Therefore, the upper leaf spring 22 is also called a front spring, and the lower leaf spring 24 is also called a rear spring.

  The upper leaf spring 22 is disposed on the upper side of the lens holder 18 in the optical axis O direction, and the lower leaf spring 24 is disposed on the lower side of the lens holder 18 in the optical axis O direction.

  The upper leaf spring 22 has an upper ring portion 222 attached to the upper end of the lens holder 18 and four upper end portions 224 attached to the four corners of the housing 12 as will be described later. Four upper arm portions 226 are provided between the upper ring portion 222 and the four upper end portions 224. That is, the four upper arm portions 226 connect the upper ring portion 222 and the four upper end portions 224.

  The upper ring portion 222 of the upper leaf spring 22 is fixed to the cylindrical portion 182 of the lens holder 18. More specifically, the lens holder 18 has four upper holder protrusions 186 that protrude radially outward from the upper end of the cylindrical portion 182. Each of the four upper holder protrusions 186 has four upper holder protrusions 186a that protrude upward. The upper ring portion 222 of the upper leaf spring 22 has four upper spring holes 222a into which the four upper holder projections 186a are respectively inserted.

  On the other hand, the four upper end portions 224 of the upper leaf spring 22 are fixed to the pair of base front protrusions 144 and the pair of base rear protrusions 146 of the actuator base 14. More specifically, the four upper end portions 224 of the upper leaf spring 22 are a pair of base front protrusions 144 a formed on the pair of base front protrusions 144 and a pair of base rear protrusions 146, respectively. It has four upper end holes 224a into which the base rear protrusion 146a is inserted.

  On the other hand, the lower leaf spring 24 has a lower inner ring portion 242 attached to the lower end portion of the lens holder 18 and a lower outer ring portion 244 attached to the actuator base 14. Four lower arm portions 246 are provided between the lower inner ring portion 242 and the lower outer ring portion 244. That is, the four lower arm portions 246 connect the lower inner ring portion 242 and the lower outer ring portion 244.

  In the illustrated example, the number of the lower arm portions 246 is four, but a plurality of lower arm portions 246 may be provided.

  The elastic member 20 including the upper leaf spring 22 and the lower leaf spring 24 serves as a guide means for guiding the lens holder 18 so as to be movable only in the direction of the optical axis O. Each of the upper leaf spring 22 and the lower leaf spring 24 is made of beryllium copper, phosphor bronze, or the like.

  With such a configuration, the lens movable portions (11, 18) can move only in the direction of the optical axis O with respect to the housing (housing) 12.

  The lens driving device 10 is electrically connected to a linear shape memory alloy wire 28 disposed in the vicinity of the outer wall of the cylindrical portion 182 of the lens holder 18 and both ends of the shape memory alloy wire 28. And a pair of pipe-shaped electrodes 30. The combination of a shape memory alloy (SMA) wire 28 and a pair of pipe electrodes 30 is referred to as a shape memory alloy (SMA) assembly 32. The SMA assembly 32 is held by a pair of base front protrusions 144 of the actuator base 14 as will be described later.

  FIG. 6 is a perspective view showing the appearance of the pipe electrode 30.

  As shown in FIG. 4, the pair of pipe-shaped electrodes 30 have a symmetrical shape. The pair of pipe electrodes 30 substantially extend in the up-down direction Z. The pair of pipe-shaped electrodes 30 includes a pair of main cylindrical portions 302 extending in parallel with each other and a pair of distal ends bent at an acute angle from the distal ends (upper ends) of the main cylindrical portions 302 toward the adjacent sides. It is comprised from the cylindrical part 304. FIG.

  In the example shown in the figure, the diameter of the shape memory alloy (SMA) wire 28 is 50 μm, and the inner diameter of the pipe electrode 30 is 0.3 mm. Further, both end portions of the shape memory alloy wire 28 are inserted into a pair of pipe-shaped electrodes 30. Both ends of the shape memory alloy wire 28 are inserted not only into the pair of distal end tubular portions 304 of the pair of pipe electrodes 30 but also into the pair of main tubular portions 302. That is, the pair of pipe-shaped electrodes 30 serves as a guide for the shape memory alloy wire 28. Thereby, as will be described later, the mounting load applied to the shape memory alloy wire 28 can be easily adjusted.

  In other words, as shown in FIGS. 3 and 4, each of the pair of pipe-shaped electrodes 30 includes a main cylindrical portion 302 that is held by the housing 12 and extends in parallel with the optical axis O direction, and the main cylindrical portion 302. The front end cylindrical portion 304 is bent from the front end (upper end) of the cylindrical portion 302 toward the latching protrusion 184 of the lens holder 18.

  The attachment state of the SMA assembly 32 to the pair of base front protrusions 144 of the actuator base 14 will be described with reference to FIGS.

  The pair of main cylindrical portions 302 of the pair of pipe-shaped electrodes 30 are engaged with and held by a pair of engagement grooves 144 b formed in the pair of base front protrusions 144. The pair of distal end cylindrical portions 304 of the pair of pipe-shaped electrodes 30 are positioned and held by a pair of positioning recesses 144 c formed in the pair of base front protrusions 144. As a result, the shape memory alloy wire 28 extends in a plane defined by the vertical direction Z and the horizontal direction Y. Each pipe electrode 30 is electrically connected to the end portion of the shape memory alloy wire 28 by caulking the lower end portion of the main cylindrical portion 302 as will be described later. That is, the pair of pipe-shaped electrodes 30 respectively have crimped portions 302 a that are electrically connected to both ends of the shape memory alloy wire 28 at the tail end of the main cylindrical portion 302.

  In this way, the SMA assembly 32 is attached to the pair of base forward protrusions 144 of the actuator base 14. The intermediate portion 28 a of the shape memory alloy wire 28 is hooked with the protruding portion (holding protrusion) 184 of the lens holder 18. That is, the shape memory alloy wire 28 is stretched between the lens holder 18 and the housing 12.

  Next, a schematic operation of the lens driving device 10 will be described.

  As is well known, a “shape memory alloy” is a metal having a property that a given deformation strain becomes zero in a specific temperature region and recovers to its original shape. The shape memory alloy is made of, for example, a TiNi alloy.

  The shape memory alloy wire 28 shown in the drawing contracts to a pre-stored contraction length when self-heating is caused by energization, and to the original length (relaxed length) determined by natural cooling when the energization is stopped. It is a return type wire.

  The elastic member 20 acts to urge the lens holder 18 downward along the optical axis O direction. On the other hand, the shape memory alloy wire 28 contracts when energized through a pair of pipe electrodes 30 from a drive circuit (not shown). As a result, the lens holder 18 moves upward along the optical axis O direction against the downward biasing force of the elastic member 20.

  On the other hand, when the energization to the shape memory alloy wire 28 is stopped, the shape memory alloy wire 28 is naturally cooled. As a result, the shape memory alloy wire 28 expands due to the downward biasing force of the elastic member 20. As a result, the lens holder 18 moves downward along the optical axis O direction.

  That is, the shape memory alloy wire 28 expands and contracts in the direction of the optical axis O due to a temperature change caused by energization / non-energization, and functions as a moving unit that moves the lens holder 18 in the direction of the optical axis O.

  The combination of the elastic member 20 and the SMA assembly 32 is a lens driving unit (20, 20) that drives the lens moving unit (11, 18) while supporting the lens moving unit (11, 18) so as to be movable in the optical axis O direction. 32).

  The lens driving unit (20, 32) and the lens movable unit (11, 18) are juxtaposed with respect to the optical axis O as shown in FIG. Therefore, the lens driving device 10 can be reduced in height.

  Next, with reference to FIG. 7 and FIG. 8, a method for inserting both ends of the shape memory alloy wire 28 into the pair of pipe-shaped electrodes 30 will be described. FIG. 7 is a front view of the lens driving device 10 with the upper cover 16 omitted in order to explain the flow of the process of inserting the shape memory alloy wire 28. 8A is a cross-sectional view showing a state before the pipe-shaped electrode 30 is caulked to the shape memory alloy wire 28, and FIG. 8B is a view after the pipe-shaped electrode 30 is caulked to the shape memory alloy wire 28. It is sectional drawing which shows a state.

  In FIG. 7, in order to distinguish the pair of pipe-shaped electrodes 30, the left-side pipe-shaped electrode that is one pipe-shaped electrode is denoted by a reference sign of 30 L, and the right-side pipe-shaped electrode that is the other pipe-shaped electrode 30 is denoted. Reference numeral 30R is attached.

  As shown in FIG. 7A, first, the shape memory alloy wire 28 is moved through the pair of pipe electrodes 30 from the lower end (tail end) of the left pipe electrode 30L to the lower end of the right pipe electrode 30R ( It is inserted into the pair of pipe electrodes 30 while being guided to the tail end). At this time, the intermediate portion 28 a of the shape memory alloy wire 28 is hooked on the hooking protrusion 184 of the lens holder 18. At this time, as shown in FIG. 7A, a part of the shape memory alloy wire 28 is exposed (protruded) from the lower end (tail end) of the right pipe electrode 30R.

  Next, at the lower end portion (tail end portion) of the main cylindrical portion 302 of the left pipe electrode 30L at the position indicated by the arrow A in FIG. 7A, the left pipe electrode 30L and the shape memory alloy. The wire 28 is crimped as shown in FIG.

  Subsequently, as indicated by an arrow B in FIG. 7A, one of the shape memory alloy wires 28 exposed (projected) from the lower end (tail end) of the main cylindrical portion 302 of the right pipe electrode 30R. The holding load is applied to the intermediate portion 28a of the shape memory alloy wire 28 at the latching protrusion 18 by vertically moving the shape memory alloy wire 28 along the vertical direction Z (projection direction thereof). Adjust.

  After adjusting the mounting load, at the lower end portion (tail end portion) of the main cylindrical portion 302 of the right pipe electrode 30R at the position indicated by the arrow C in FIG. The memory alloy wire 28 is caulked as shown in FIG.

  Thereafter, a part of the shape memory alloy wire 28 exposed (projected) from the lower end (tail end) of the main tubular portion 302 of the right pipe electrode 30R is cut.

  The lens driving device 10 according to the first embodiment described above has the following effects.

  As described with reference to FIGS. 7A and 7B, the attachment load applied to the shape memory alloy wire 28 can be easily adjusted.

  Further, as shown in FIGS. 8A and 8B, the electrical connection work (caulking process) between the shape memory alloy wire 28 and the pair of pipe-shaped electrodes 30 can be easily performed. That is, it is possible to freely select a caulking point (electrical connection point) by using the pipe electrode 30 according to the embodiment of the present invention, rather than folding and caulking an electrode made of a conventional metal piece, and Can be caulked reliably.

  Furthermore, since the effective length of the shape memory alloy wire 28 (that is, the wire length between the electrical connection points (caulking points)) can be increased, the lens displacement amount (the stroke amount of the lens movable portion (11, 18)). Can be increased. The reason is as follows. In the lens driving device 10 according to the present embodiment, the shape memory alloy wire 28 can be extended to the bottom surface side of the actuator base 14 along the pair of pipe-shaped electrodes 30. Therefore, the pair of pipe electrodes 30 and the shape memory alloy wire 28 can be caulked at the lower ends (tail ends) of the pair of pipe electrodes 30. For this reason, the amount of shrinkage of the shape memory alloy wire 28 can be increased. As a result, the amount of lens displacement can be increased.

  Next, a lens driving device 10A according to a second embodiment of the present invention will be described with reference to FIG. FIG. 9 is a front view showing the lens driving device 10A in a state where the lens barrel 11 and the upper cover 16 are omitted.

  The illustrated lens driving device 10A is the same as the lens driving device 10 shown in FIGS. 1 to 5 except that a specific resin as described later is injected (applied) into the pair of pipe-shaped electrodes 30. It has a structure and operates. The same components as those of the lens driving device 10 are denoted by the same reference numerals, description thereof will be omitted, and only differences will be described below.

  In the illustrated lens driving device 10A, as indicated by an arrow D in FIG. 9, a conductive resin is used as a specific resin from the lower end (tail end) of the main cylindrical portion 302 of the pair of pipe-shaped electrodes 30 to the inside thereof. Is injected (applied). For example, a silver paste can be used as the conductive resin. This makes it possible to reliably establish conduction between the pair of pipe electrodes 30 and the shape memory alloy wire 28.

  In the lens driving device 10A shown in FIG. 9, a conductive resin is used as the specific resin. However, instead of the conductive resin, an attachment reinforcing resin for the shape memory alloy wire 28 may be used. In this case, the shape memory alloy wire 28 can be securely attached to the pair of pipe-shaped electrodes 30.

  At any rate, in the lens driving device according to the present invention, it is possible to inject (apply) a specific resin after the product is completed.

  Next, a lens driving device 10B according to a third embodiment of the present invention will be described with reference to FIGS. FIG. 10 is a perspective view of the lens driving device according to the third embodiment of the present invention, with the lens barrel and the outer upper cover omitted, viewed obliquely from the upper front, and FIG. 11 shows the pipe-shaped electrode as a shape memory alloy. FIG. 12 is an explanatory diagram schematically showing a state before caulking to a wire, and FIG. 12 is an explanatory diagram schematically showing a state after caulking a pipe electrode to a shape memory alloy wire.

  The lens driving device 10B shown in FIG. 1 is the same as that of FIG. 1 to FIG. It has the same configuration as the lens driving device 10 shown in FIG. 5 and operates. The same components as those of the lens driving device 10 are denoted by the same reference numerals, description thereof will be omitted, and only differences will be described below.

  In the illustrated lens driving device 10B, as shown in FIG. 10 to FIG. 12, the caulking portion 302aB formed at the tail end portion of the main cylindrical portion 302 of the pair of pipe-shaped electrodes 30 It has a concave / convex inner peripheral surface 302aB ′ that prevents escape. In addition, a concavo-convex portion corresponding to the concavo-convex inner peripheral surface 302aB 'is also formed on the outer peripheral surface side of the caulking portion 302aB.

  The concave / convex inner peripheral surface 302aB ′ is formed so as to alternately repeat a plurality of concave portions and convex portions along the longitudinal direction of the main cylindrical portion 302.

As shown in FIGS. 11 and 12, the crimping portion 302 a B is formed by using the crimping jig T having a concavo-convex surface on the pressing surface side in contact with the main tubular portion 302, and the main tubular portion 302 and the shape memory alloy. It is formed by caulking with the wire 28.
The caulking jig T shown in FIGS. 11 and 12 has concave and convex surfaces on both pressing surfaces contacting the main cylindrical portion 302, but the caulking jig T having the concave and convex surfaces only on one pressing surface. It doesn't matter what is used.

  Thereby, since the concave / convex inner peripheral surface 302aB ′ of the caulking portion 302aB and the shape memory alloy wire 28 are engaged with each other, the shape memory alloy wire 28 can be prevented from slipping out from the main cylindrical portion 302 of the pipe-shaped electrode 30, Further, since the bonding area and the number of contacts between the concave / convex inner peripheral surface 302aB ′ and the outer peripheral surface of the shape memory alloy wire 28 are increased, resistance variation between the shape memory alloy wire 28 and the pipe electrode 30 is suppressed. be able to.

  Although the present invention has been particularly shown and described with reference to the embodiments thereof, the present invention is not limited to these embodiments. It will be understood by those skilled in the art that various modifications can be made in form and detail without departing from the spirit and scope of the invention as defined in the claims. For example, the guide means (elastic member) is not limited to the above-described embodiment, and various types may be used.

10, 10A Lens drive device 11 Lens barrel (lens assembly)
12 Housing (housing)
14 Actuator base 142 Base portion 144 Base forward projection 144a Base forward projection 144b Engaging groove 144c Positioning recess 146 Base rear projection 146a Base rear projection 16 Upper cover 18 Lens holder 182 Tubular portion 184 Projection (holding projection)
186 Upper holder protrusion 186a Upper holder projection 20 Elastic member 22 Upper leaf spring 222 Upper ring portion 222a Upper spring hole
224 Upper end portion 224a Upper end portion hole 226 Upper arm portion 24 Lower leaf spring 242 Lower inner ring portion 244 Lower outer ring portion 246 Lower arm portion 28 Linear shape memory alloy wire 28a Intermediate portion 30 Pipe electrode 30L Left pipe-like electrode 30R Right-side pipe-like electrode 302 Main cylindrical portion 302a, 302aB Caulking portion 302aB 'Uneven inner peripheral surface 304 Tip cylindrical portion 32 SMA assembly O Optical axis of lens AFL Autofocus lens T Caulking jig

Claims (22)

A lens holder that includes a cylindrical portion that holds a lens barrel, a housing that supports the lens holder so as to be movable only in the optical axis direction, a moving means that moves the lens holder in the optical axis direction, and the lens holder. In a lens driving device comprising: guide means for guiding movement only in the optical axis direction;
The moving means includes a linear shape memory alloy wire stretched between the lens holder and the housing, and both ends of the shape memory alloy wire are inserted into a pair of pipe electrodes. A lens driving device.   2. The lens driving device according to claim 1, wherein the lens holder has a latching protrusion that projects radially outward from the cylindrical portion and latches an intermediate portion of the shape memory alloy wire.   Each of the pair of pipe-shaped electrodes is held by the housing and extends in parallel with the optical axis direction, and is bent from the tip of the main cylindrical portion toward the latching protrusion. The lens driving device according to claim 2, wherein the lens driving device is configured by a tip cylindrical portion.   4. The lens driving device according to claim 3, wherein the pair of pipe-shaped electrodes respectively have crimped portions that are electrically connected to both end portions of the shape memory alloy wire at the tail end portion of the main cylindrical portion.   The lens driving device according to claim 4, wherein the caulking portion has an uneven inner peripheral surface that prevents the shape memory alloy wire from coming out.   The lens driving device according to claim 4 or 5, wherein a specific resin is injected into the pair of pipe-shaped electrodes from the tail end of the main cylindrical portion.   The lens driving device according to claim 6, wherein the specific resin is a conductive resin.   The lens driving device according to claim 7, wherein the conductive resin is made of a silver paste.   The lens driving device according to claim 6, wherein the specific resin is an attachment reinforcing resin for the shape memory alloy wire.   The guide means includes an elastic member disposed between the lens holder and the housing, and the elastic member supports the lens holder so as to be displaceable only in the optical axis direction with the lens holder positioned in a radial direction. The lens driving device according to any one of claims 1 to 9.   The said elastic member is comprised from the upper side leaf | plate spring and lower side leaf | plate spring which were provided in the optical axis direction upper side and lower side of the cylindrical part of the said lens holder, respectively. Lens drive device.   The upper leaf spring includes an upper ring portion that is attached to the upper end portion of the lens holder, four upper end portions that are attached to the housing, and four upper portions that connect the upper ring portion and the four upper end portions, respectively. The lens driving device according to claim 11, comprising an arm portion. The lower leaf spring connects a lower inner ring portion attached to a lower end portion of the lens holder, a lower outer ring portion attached to the housing, and the lower inner ring portion and the lower outer ring portion. The lens driving device according to claim 11, comprising a plurality of lower arm portions. The lens driving device according to any one of claims 1 to 3, wherein both ends of the shape memory alloy wire are inserted into the pair of pipe electrodes,
Inserting the shape memory alloy wire from the tail end of one pipe-like electrode to the tail end of the other pipe-like electrode, with a part protruding from the tail end of the other pipe-like electrode;
A caulking portion is formed by caulking the one pipe-shaped electrode and the shape memory alloy wire at the tail end of the one pipe-shaped electrode;
Attaching to the shape memory alloy wire by sandwiching a part of the shape memory alloy wire protruding from the tail end of the other pipe electrode and moving the shape memory alloy wire along the protruding direction. Adjusting the load;
After the load adjustment, a step of caulking the one pipe-shaped electrode and the shape memory alloy wire at a tail end portion of the other pipe-shaped electrode,
Including charging method.   The charging method according to claim 14, wherein the caulking portion has an uneven inner peripheral surface that prevents the shape memory alloy wire from slipping out.   The charging method according to claim 14 or 15, further comprising a step of cutting a part of the shape memory alloy wire protruding from a tail end of the other pipe-shaped electrode.   The charging method according to claim 16, further comprising a step of injecting a specific resin into the inside from the tail ends of the pair of pipe-shaped electrodes.   The charging method according to claim 17, wherein the specific resin is a conductive resin.   The charging method according to claim 18, wherein the conductive resin is made of a silver paste.   The charging method according to claim 17, wherein the specific resin is an attachment reinforcing resin for the shape memory alloy wire. An SMA assembly composed of a linear shape memory alloy wire and a pair of electrodes attached to both ends of the shape memory alloy wire,
The pair of electrodes is composed of a pair of pipe electrodes into which both ends of the shape memory alloy wire are inserted.   The pair of pipe-shaped electrodes includes a pair of main cylindrical portions extending in parallel with each other, and a pair of distal end cylindrical portions bent at an acute angle from the distal ends of the pair of main cylindrical portions toward the adjacent sides. The SMA assembly of claim 21, comprising:

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