JP2010262178A - Lens drive device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten the length of a shape memory alloy linear material used. <P>SOLUTION: A guide means for guiding a lens holder (18) so that it is movable only in the direction of an optical axis (O) includes an elastic member (20) disposed between a lens holder (18) and a housing (12). The elastic member (20) supports the lens holder (18) so that the lens holder (18) is movable only in the direction of the optical axis (O) while positioned in a radial direction. A moving means for moving the lens holder (18) in the direction of the optical axis (O) includes the shape memory alloy linear material (28) that is disposed near the external wall of the cylindrical portion (182) of the lens holder (18) and engages with the lens holder. The shape memory alloy linear material (28) has at least one inflection point (28-1). <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a lens driving device, and more particularly to a lens driving device using a shape memory alloy for an actuator.

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

  For example, Japanese Patent Laid-Open No. 9-127398 (Patent Document 1) discloses a lens driving mechanism having a simple configuration. The lens driving mechanism disclosed in Patent Document 1 includes a moving lens unit that is supported by a guide bar in a lens barrel and moves between fixed lenses on both sides of the lens barrel. A spring material is arranged between the moving lens unit and both fixed lens units. At least one of the spring members is a shape memory alloy spring. The movement of the moving lens unit is controlled by heating or cooling the spring material.

  Japanese Patent Laying-Open No. 2006-98829 (Patent Document 2) discloses a lens driving device that can move a lens smoothly and quickly and is miniaturized so as to be incorporated into a portable information terminal. The lens driving device disclosed in Patent Document 2 includes a lens frame (lens holder) that holds a lens and a cylindrical support portion that supports the lens frame (lens holder) so as to be movable only in the optical axis direction. A frame and a coil spring that can expand and contract in the optical axis direction are provided. The coil spring includes a shape memory alloy spring formed of a shape memory alloy that is concentrically exposed to the outside of the cylindrical support portion and that expands and contracts in the optical axis direction due to a temperature change caused by energization / non-energization. The cylindrical outer peripheral surface of the lens frame (lens holder) is slidably fitted to the inner peripheral surface of the cylindrical support portion of the fixed frame.

  As an embodiment disclosed in Patent Document 2, the coil spring includes a front coil spring and a rear coil spring arranged concentrically around the optical axis on the outside of the cylindrical support portion. The front coil spring and the rear coil spring urge the lens frame from the front side and the rear side in the optical axis direction. At least one of the front coil spring and the rear coil spring is formed of a shape memory alloy.

JP-A-9-127398 (paragraphs 0015 to 0017, FIGS. 3 and 4) JP 2006-98829 A (paragraphs 0009 to 0020, FIGS. 1 to 5)

  The lens driving mechanism disclosed in Patent Document 1 and the lens driving device disclosed in Patent Document 2 have problems as described below.

  In the lens driving mechanism disclosed in Patent Document 1, the moving lens unit is supported by a guide bar so as to be movable. That is, the guide bar acts as a guide means for guiding the movable lens portion only in the optical axis direction. The movement of the moving lens portion in the focus direction (optical axis direction) is restricted by the sliding surface of the guide bar. Accordingly, a frictional force acts between the movable lens portion and the guide bar (sliding surface). In such a guide means, the shape memory alloy spring needs to move the movable lens portion only in the optical axis direction against this frictional force. As a result, a shape memory alloy spring having a large urging force (driving force) must be used. In other words, the shape memory alloy spring becomes expensive. In addition, the frictional force may hinder the thrust (driving force; urging force) generated by the shape memory alloy spring.

  Moreover, in patent document 1, since the shape memory alloy spring is coiled, the length of the shape memory alloy wire which comprises the shape memory alloy spring will become long.

  In the lens driving device disclosed in Patent Document 2, a shape memory alloy spring is disposed so as to be exposed outside the cylindrical support portion. Therefore, the vertical and horizontal sizes of the lens driving device are increased. On the contrary, if the vertical and horizontal sizes of the lens driving device are reduced, the diameter of the lens held in the lens frame (lens holder) is also reduced.

  In Patent Document 2, a lens frame (lens holder) is slidably disposed on the inner peripheral surface of the cylindrical support portion of the fixed frame. That is, the cylindrical support portion of the fixed frame functions as a guide means for guiding the lens frame (lens holder) only in the optical axis direction. Therefore, a frictional force acts between the cylindrical outer peripheral surface of the lens frame (lens holder) and the inner peripheral surface of the cylindrical support portion of the fixed frame. Therefore, the shape memory alloy spring needs to move the lens frame (lens holder) only in the optical axis direction against this frictional force. As a result, a shape memory alloy spring having a large urging force (driving force) must be used. In other words, the shape memory alloy spring becomes expensive.

  Similarly to Patent Document 1, in Patent Document 1, since the shape memory alloy spring has a coil shape, the length of the shape memory alloy wire constituting the shape memory alloy spring becomes long.

  Accordingly, an object of the present invention is to provide a lens driving device capable of moving the lens holder only in the optical axis direction without sliding the lens holder holding the lens with respect to other members. is there.

  Another object of the present invention is to provide a lens driving device capable of reducing the vertical and horizontal sizes without reducing the lens diameter.

  Still another object of the present invention is to provide a lens driving device capable of shortening the length of the shape memory alloy wire used.

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

  According to the present invention, the lens holder (18; 18A) having the cylindrical portion (182) for holding the lens barrel (11), and the housing that supports the lens holder so as to be movable only in the optical axis (O) direction. (12) and a lens driving device (10; 10A; 10B) comprising: a moving means for moving the lens holder in the optical axis (O) direction; and a guiding means for guiding the lens holder so as to be movable only in the optical axis direction. ), The guide means includes an elastic member (20) disposed between the lens holder (18; 18A) and the housing (12), which elastic member moves the lens holder (18; 18A) in the radial direction. In a positioned state, it is supported so as to be displaceable only in the direction of the optical axis (O), and the moving means is disposed in the vicinity of the outer wall of the cylindrical portion (182) of the lens holder and is linearly engaged with the lens holder. Memory Gold material consists (28;; 28A 28B), the shape memory alloy wire has at least one inflection point (28-1 to 28-4), the lens driving device is obtained, characterized in that.

  In the lens driving device (10; 10A; 10B) according to the present invention, the elastic member (20) is a pair provided on both sides in the optical axis (O) direction of the cylindrical portion (182) of the lens holder (18; 18A). Plate springs (22, 24). In this case, each of the pair of leaf springs (22, 24) includes an inner peripheral end (222; 242) attached to the lens holder (18; 18A) and an outer peripheral end attached to the housing (12). (224; 244). The lens holder (18; 18A) may have at least one protrusion (184, 186) that protrudes radially outward from the tubular part (182) and engages the shape memory alloy wire. The housing (12) may be composed of an actuator base (14; 14A) disposed on the lower side of the lens holder and an upper cover (12) that covers the lens holder from above. In this case, the lens driving device is fixed to the actuator base (14; 14A) and electrically connected to the first and second ends of the shape memory alloy wire (28; 28A; 28B), respectively. There may be first and second electrodes (31, 32; 32A).

  In the lens driving device (10) according to the first aspect of the present invention, the shape memory alloy wire (28) has one inflection point (28-1), and the angle (θ1) of this inflection point (28-1). ) Is less than 90 °.

  In the lens driving device (10A) according to the second aspect of the present invention, the shape memory alloy wire (28A) has a plurality of inflection points (28-1 to 28-3), and the angle (θ2) of each inflection point. Is less than 45 °.

  In the lens driving device (10B) according to the third aspect of the present invention, the lens holder (18) protrudes radially outward from the cylindrical portion (182) at positions facing each other, and the shape memory alloy wire (28B) and The first and second electrodes (31, 32A) have first and second protrusions (284, 186) to be engaged, and are arranged at both ends of the actuator base (14A), respectively. The memory alloy wire (28B) includes an arcuate portion (283B) arranged in an arc along the outer wall of the cylindrical portion (182) of the lens holder (18A). in this case. The shape memory alloy wire (28B) has a plurality of inflection points (28-1 to 28-4), and the angle (θ3) of each inflection point is less than 90 °.

  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 elastic member disposed between the lens holder and the housing supports the lens holder so that it can be displaced only in the optical axis direction with the lens holder positioned in the radial direction. The lens holder can be moved only in the optical axis direction without sliding. Further, the moving means for moving the lens holder in the optical axis direction is formed of a linear shape memory alloy wire disposed near the outer wall of the cylindrical portion of the lens holder and engaged with the lens holder. Since the wire has at least one inflection point, the vertical and horizontal sizes can be reduced without reducing the lens diameter. Furthermore, since the moving means is composed of a linear shape memory alloy wire having at least one inflection point, the length of the shape memory alloy wire to be used can be shortened.

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 apparatus shown in FIG. 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. FIG. 6 is a partially enlarged perspective view showing an enlarged main part of the lens driving device shown in FIG. 5. It is the perspective view which looked at the lens drive device which concerns on the 2nd Embodiment of this invention from diagonally forward upper direction in the state which excluded the lens barrel and the upper cover. It is a front view of the lens drive device shown in FIG. It is the perspective view which looked at the lens drive device which concerns on the 3rd Embodiment of this invention from the diagonally forward upper direction in the state which excluded the lens barrel and the upper cover. It is the perspective view which looked at the lens drive device shown in FIG. 9 from diagonally backward upper direction. FIG. 10 is a front view of the lens driving device shown in FIG. 9. It is a perspective view which shows arrangement | positioning of a lens holder, a shape memory alloy wire, and a pair of electrode of the lens drive device shown in FIG.

  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 4. 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 viewed obliquely from above and in a state where the lens barrel 11 is omitted.

  Here, as shown in FIGS. 1 to 4, an orthogonal coordinate system (X, Y, Z) is used. In the state illustrated in FIGS. 1 to 4, 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 4, the vertical direction Z is the direction of the optical axis O of the lens.

  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 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. As shown in FIGS. 2 and 3, 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 protrusion 184 is for engaging with a part of a linear shape memory alloy wire 28 described later.

  The actuator base 14 has four projecting portions 142 projecting upward in the vertical direction Z at the four corners. Each of the four protrusions 142 has four protrusions 142a that protrude upward.

  The lens driving device 10 includes a pair of leaf springs 22 and 24 provided on both sides of the cylindrical portion 182 of the lens holder 18 in the optical axis O direction. The pair of leaf springs 22 and 24 is disposed between the lens holder 18 and the housing 12 and functions as an elastic member 20 that supports the lens holder 18 so as to be displaceable in the optical axis O direction in a state where the lens holder 18 is positioned in the radial direction. Of the pair of leaf springs 22, 24, one leaf spring 22 is called an upper leaf spring, and the other leaf spring 24 is called a lower leaf spring.

  Further, as described above, in an 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 and the lower leaf spring 24 have substantially the same configuration.

  That is, the upper leaf spring 22 has an inner peripheral end 222 attached to the lens holder 18 and an outer peripheral end 224 attached to the housing 12 as will be described later. Three arms are provided between the inner peripheral end 222 and the outer peripheral end 224. Each arm portion connects the inner peripheral end 222 and the outer peripheral end 224.

  Similarly, the lower leaf spring 24 has an inner peripheral end 242 attached to the lens holder 18 and an outer peripheral end 244 attached to the housing 12 as will be described later. Three arms are provided between the inner peripheral end 242 and the outer peripheral end 244. Each arm portion connects the inner peripheral side end 242 and the outer peripheral side end 244.

  The inner peripheral end is also called an inner ring, and the outer peripheral end is also called an outer ring.

  An inner peripheral end 222 of the upper leaf spring 22 is fixed to the cylindrical portion 182 of the lens holder 18. On the other hand, the outer peripheral side end 224 of the upper leaf spring 22 is fixed to the four protrusions 142 of the actuator base 14. The outer peripheral side end 224 has four holes 224a at four corners. As shown in FIG. 3, four protrusions 142a formed on the four protrusions 142 are inserted into the four holes 224a, respectively.

  On the other hand, the outer end 244 of the lower leaf spring 24 is fixed to the actuator base 14 by a leaf spring holder 26. In other words, the outer peripheral end 244 of the lower leaf spring 24 is sandwiched and fixed between the leaf spring holder 26 and the actuator base 12. An inner peripheral side end 242 of the lower leaf spring 24 is fixed to the bottom surface side of the lens holder 18.

  The elastic member 20 including the pair of leaf springs 22 and 24 serves as a guide unit that guides the lens holder 18 so as to be movable only in the direction of the optical axis O. Each of the pair of leaf springs 22 and 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 includes 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 first and second ends 28 a and 28 b of the shape memory alloy wire 28. First and second electrodes 31 and 32 that are electrically connected to each other are provided.

  In addition to FIGS. 3 and 4, the mounting state of the shape memory alloy wire 28 will be described with reference to FIGS. 5 and 6. FIG. 5 is a front view of the lens driving device 10 shown in FIG. FIG. 6 is a partially enlarged perspective view showing an enlarged main part of the lens driving device 10 shown in FIG.

  As shown in FIG. 4, the leaf spring holder 26 has a ring portion 262 having a substantially ring shape. A groove 264 is formed in the front portion of the ring portion 262 in the front-rear direction X. The leaf spring holder 26 has a protruding portion 266 that protrudes upward in the vertical direction Z in the vicinity of the groove 264.

  On the other hand, the actuator base 14 has a first groove 144 formed at a position corresponding to the groove 264 and a second groove 146 formed at a position corresponding to the protrusion 266.

  Although the first and second electrodes 31 and 32 extend in the vertical direction Z, the second electrode 32 is longer than the first electrode 31. As shown in FIG. 6, the first electrode 31 is fixed by the first groove 144 of the actuator base 14 and is erected along the groove 264 of the leaf spring holder 26. On the other hand, the second electrode 32 is fixed by the second groove 146 of the actuator base 14 and is held upright by the protruding portion 266 of the leaf spring holder 26.

  As shown in FIG. 6, the first electrode 31 has a first connection portion 312 bent at the upper end portion thereof in a U-shaped cross section. Similarly, the 2nd electrode 32 has the 2nd connection part 322 bent by the cross-sectional U-shape in the upper end part. The first electrode 31 is electrically connected to the first end portion 28 a of the shape memory alloy wire 28 by caulking the first connection portion 312. Similarly, the second electrode 32 is electrically connected to the second end portion 28 b of the shape memory alloy wire 28 by caulking the second connection portion 322.

  In this manner, the shape memory alloy 28 is attached to the actuator base 14 while being electrically connected to the first and second electrodes 31 and 32.

  The shape memory alloy wire 28 includes a first straight portion 281 extending leftward in the left-right direction Y from the first connection portion 312 of the first electrode 31 and a second connection portion 322 of the second electrode 32. A second straight portion 282 extending to the left in the left-right direction Y, and a connecting portion 283 that connects the first straight portion 281 and the second straight portion 282.

  In the illustrated example, the connecting portion 283 has a substantially linear shape. At the connecting portion 283, the protruding portion 184 of the lens holder 18 is engaged. The shape memory alloy wire 28 has one inflection point (bending point) 28-1 at the connecting portion between the first straight portion 281 and the connecting portion 283. The angle θ1 of the inflection point (bending point) 28-1 is less than 90 °.

  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 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 expands when energized 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 contracts 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 shape memory alloy wire 28 is a lens driving unit (11, 18) 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. 20, 28).

  The lens driving unit (20, 28) 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.

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

  Since the elastic member 20 disposed between the lens holder 18 and the housing 12 is used as the guide means, the lens holder 18 is moved in the optical axis O direction without sliding the lens holder 18 with respect to other members. Can only be moved to.

  Since the shape memory alloy wire 28 is disposed in the vicinity of the outer wall of the cylindrical portion 182 of the lens holder 18, the vertical and horizontal sizes of the lens driving device 10 are reduced without reducing the lens diameter of the autofocus lens AFL which is a movable lens. can do. As a result, the diameter of the autofocus lens AFL can be increased, and a high-resolution camera can be supported.

  Further, since the linear shape memory alloy wire rod 28 having at least one inflection point (bending point) 28-1 is used as the moving means, the shape is compared with the coiled shape memory alloy spring. The total length of the memory alloy wire 28 can be shortened. As a result, the lens driving device 10 can be reduced in size.

  By increasing the angle θ1 of the inflection point (bending point) 28-1, the shape recovery force of the shape memory alloy wire rod back 28 can be increased. As a result, the lens thrust of the lens driving device 10 can be improved.

  In addition, since the place which performs the work of a drive is only the part of the inflection point (bending point) 28-1 of the shape memory alloy wire 28, the other linear parts 281, 282, and 283 are directly involved in the drive. small.

  A lens driving device 10A according to a second embodiment of the present invention will be described with reference to FIGS. FIG. 7 is a perspective view of the lens driving device 10 </ b> A as viewed obliquely from above and in a state where the lens barrel 11 and the upper cover 16 are omitted. FIG. 8 is a front view of the lens driving device 10A shown in FIG.

  The illustrated lens driving device 10A has the same configuration as the lens driving device 10 shown in FIGS. 1 to 6 except that the configuration of the linear shape memory alloy wire is different as will be described later. To work. Therefore, reference numeral 28A is attached to the shape memory alloy wire. 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.

  The shape memory alloy wire 28A has the same configuration as the shape memory alloy wire 28 shown in FIGS. 3 to 6 except that the configuration of the connecting portion is different as will be described later. Therefore, the reference numeral 283A is attached to the connecting portion.

  The connecting portion 283A is substantially S-shaped. More specifically, the connecting portion 283A extends from the distal end portion of the first linear portion 281 obliquely upward to the right and from the distal end portion of the second linear portion 282 to obliquely lower left. The second connecting straight line portion 283A2 and the third connecting straight line portion 283A3 connecting the first connecting straight line portion 283A1 and the second connecting straight line portion 283A2 are formed. The protrusion 184 of the lens holder 18 is engaged with the second connecting straight line portion 283A2.

  The shape memory alloy wire 28A includes a first inflection point (bending point) 28-1 at a connection portion between the first straight portion 281 and the first connecting straight portion 283A1, a first connecting straight portion 283A1, and The second inflection point (bending point) 28-2 at the connection portion with the third connection straight line portion 283A1, and the second connection point between the second connection straight line portion 283A2 and the third connection straight line portion 283A3. 3 inflection points (bending points) 28-2. The angle θ2 of each of the first to third inflection points (bending points) 28-1 to 28-3 is less than 45 °.

  The lens driving device 10A having such a configuration operates in the same manner as the lens driving device 10 according to the first embodiment described above, and thus the description of the operation is omitted.

  In any case, the shape memory alloy wire 28 </ b> A 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 shape memory alloy wire 28A is a lens driving unit that drives the lens moving part (11, 18) while supporting the lens moving part (11, 18) so as to be movable in the optical axis O direction. 20, 28A).

  The lens driving section (20, 28A) and the lens movable section (11, 18) are juxtaposed with respect to the optical axis O as shown in FIG. Therefore, the lens driving device 10A can be reduced in height.

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

  Since the elastic member 20 disposed between the lens holder 18 and the housing 12 is used as the guide means, the lens holder 18 is moved in the optical axis O direction without sliding the lens holder 18 with respect to other members. Can only be moved to.

  Since the shape memory alloy wire 28A is disposed in the vicinity of the outer wall of the cylindrical portion 182 of the lens holder 18, the vertical and horizontal sizes of the lens driving device 10A are reduced without reducing the lens diameter of the autofocus lens AFL which is a movable lens. can do. As a result, the diameter of the autofocus lens AFL can be increased, and a high-resolution camera can be supported.

  Further, since the linear shape memory alloy wire rod 28A having the first to third inflection points (bending points) 28-1 to 28-3 is used as the moving means, the coiled shape memory alloy is used. Compared with the spring, the total length of the shape memory alloy wire 28A can be shortened. As a result, the lens driving device 10A can be reduced in size.

  By increasing the angle θ2 of each of the first to third inflection points (bending points) 28-1 to 28-3, the shape recovery force of the shape memory alloy wire back 28A can be increased. As a result, the lens thrust of the lens driving device 10A can be improved. Further, since the shape memory alloy wire rod back 28A has three inflection points (bending points) 28-1 to 28-3, it becomes possible to increase the thrust during lens focusing.

  A lens driving device 10B according to a third embodiment of the present invention will be described with reference to FIGS. FIG. 9 is a perspective view of the lens driving device 10B as viewed obliquely from above and in the state in which the lens barrel 11 and the upper cover 16 are omitted. FIG. 10 is a perspective view of the lens driving device 10B shown in FIG. FIG. 11 is a front view of the lens driving device 10B shown in FIG. FIG. 12 is a perspective view showing the arrangement of the lens holder, the shape memory alloy wire, and the pair of electrodes of the lens driving device 10B shown in FIG.

  The lens driving device 10B shown in FIG. 1 is the same as that shown in FIG. 1 to FIG. 1 except that the configuration of the linear shape memory alloy wire, the actuator base, the leaf spring holder, the second electrode, and the lens holder is different. It has the same configuration as the lens driving device 10 shown in FIG. 6 and operates. Accordingly, reference numerals 28B, 14A, 26A, 32A, and 18A are assigned to the shape memory alloy wire, the actuator base, the leaf spring holder, the second electrode, and the lens holder, respectively. 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.

  First, the attachment state of the shape memory alloy wire 28B will be described.

  The leaf spring holder 26A has the same configuration as that of the leaf spring holder 26 except that the leaf spring holder 26A has a second groove 266A instead of the protruding portion 266. As shown in FIG. 10, the second groove 266 </ b> A is formed in the rear portion of the ring portion 26 in the front-rear direction X.

  The actuator base 14A has the same configuration as the actuator base 14 except that the location where the second groove is formed is different. Therefore, the reference numeral 146A is attached to the second groove. As shown in FIG. 10, the second groove 146A is formed at a position corresponding to the second groove 266A of the leaf spring holder 26A at the rear portion of the actuator base 14A in the front-rear direction X.

  The second electrode 32A is different from the second electrode 32 in length and location. That is, the second electrode 32 </ b> A has the same length as the first electrode 31. As shown in FIG. 10, the second electrode 32A is fixed on the back surface of the actuator base 14A by the second groove 146A of the actuator base 14A, and stands along the second groove 266A of the leaf spring holder 26A. Has been established. The second electrode 32A has a second connection portion 322A bent in a U-shaped cross section at its upper end.

  The first electrode 31 is electrically connected to the first end of the shape memory alloy wire 28 </ b> B by caulking the first connection portion 312. Similarly, the second electrode 32A is electrically connected to the second end portion of the shape memory alloy wire 28B by caulking the second connection portion 322A.

  In this manner, the shape memory alloy 28B is attached to the actuator base 14A while being electrically connected to the first and second electrodes 31, 32A.

  The lens holder 18 </ b> A has the same configuration as the lens holder 18 except that the lens holder 18 </ b> A further includes a second protrusion 186. Here, the protrusion 184 is also referred to as a first protrusion. As shown in FIG. 10, the second projecting portion 186 is provided on the outer peripheral wall of the cylindrical portion 182 of the lens holder 18 </ b> A so as to project outward in the radial direction behind the front-rear direction X. The second protrusion 186 also engages with the linear shape memory alloy wire 28B as will be described later.

  The shape memory alloy wire 28B has the same configuration as the shape memory alloy wire 28 shown in FIGS. 3 to 6 except that the configurations of the second linear portion and the connecting portion are different as will be described later. . Therefore, reference numerals 282A and 283B are attached to the second straight line portion and the connecting portion, respectively.

  As shown in FIG. 10, the second straight portion 282A extends to the left in the left-right direction Y from the second connection portion 322A of the second electrode 32A on the back side of the lens driving device 10B. .

  The connecting portion 283B is disposed along the outer peripheral wall of the cylindrical portion 182 of the lens holder 18A. More specifically, the connecting portion 283B extends from the front end portion of the first straight portion 281 obliquely upward to the right and from the front end portion of the second straight portion 282A to the upper right. The second connecting straight line portion 283B2 and the connecting circular arc portion 283B3 that connects the first connecting straight line portion 283B1 and the second connecting straight line portion 283B2 in an arc shape. The first and second protrusions 184 and 186 of the lens holder 18A are engaged with each other at the connecting arcuate portion 283B3.

  The shape memory alloy wire 28B includes a first inflection point (bending point) 28-1 at a connection portion between the first straight line portion 281 and the first connecting straight line portion 283B1, and the first connecting straight line portion 283B1. The second inflection point (bending point) 28-2 at the connection portion with the connection arcuate portion 283B3, and the third inflection point at the connection portion between the connection arcuate portion 283B3 and the second connection straight line portion 283B2. It has a point (bending point) 28-3 and a fourth inflection point (bending point) 28-4 at the connecting portion between the second connecting straight line portion 283B2 and the second straight line portion 282A. The angle θ3 of each of the first to fourth inflection points (bending points) 28-1 to 28-4 is less than 90 °.

  Since the lens driving device 10B having such a configuration operates in the same manner as the lens driving device 10 according to the first embodiment described above, description of the operation is omitted.

  In any case, the shape memory alloy wire 28B 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 means for moving the lens holder 18A in the direction of the optical axis O.

  The combination of the elastic member 20 and the shape memory alloy wire 28B is a lens driving unit (11, 18A) for driving the lens moving unit (11, 18A) while supporting the lens moving unit (11, 18A) movably in the optical axis O direction. 20, 28B).

  The lens driving unit (20, 28B) and the lens movable unit (11, 18A) are juxtaposed with respect to the optical axis O as shown in FIG. Therefore, the lens driving device 10A can be reduced in height.

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

  Since the elastic member 20 disposed between the lens holder 18A and the housing 12 is used as the guide means, the lens holder 18A is moved in the direction of the optical axis O without sliding the lens holder 18A with respect to other members. Can only be moved to.

  Since the shape memory alloy wire 28B is disposed in the vicinity of the outer wall of the cylindrical portion 182 of the lens holder 18A, the vertical and horizontal sizes of the lens driving device 10B are reduced without reducing the lens diameter of the autofocus lens AFL which is a movable lens. can do. As a result, the diameter of the autofocus lens AFL can be increased, and a high-resolution camera can be supported.

  Moreover, since the linear shape memory alloy wire rod 28B having the first to fourth inflection points (bending points) 28-1 to 28-4 is used as the moving means, the coiled shape memory alloy is used. Compared with the spring, the total length of the shape memory alloy wire 28B can be shortened. As a result, the lens driving device 10B can be downsized.

  By increasing the angle θ3 of each of the first to fourth inflection points (bending points) 28-1 to 28-4, the shape recovery force of the shape memory alloy wire rod 28B can be increased. As a result, the lens thrust of the lens driving device 10B can be improved. Further, since the shape memory alloy wire rod 28B has four inflection points (bending points) 28-1 to 28-4, it is possible to increase the thrust during lens focusing.

  Although the present invention has been described with reference to preferred embodiments, it is obvious that various modifications can be made by those skilled in the art without departing from the spirit of the present invention. For example, in the above-described embodiment, the elastic member is composed of a pair of leaf springs provided on both sides in the optical axis direction of the cylindrical portion of the lens holder. Any configuration may be used as long as it can be guided without sliding with respect to the member.

10, 10A, 10B Lens drive device 11 Lens barrel (lens assembly)
12 Housing (housing)
14, 14A Actuator base 16 Upper cover 18, 18A Lens holder 182 Cylindrical portion 184, 186 Protruding portion 20 Elastic member 22, 24 Leaf spring 26, 26A Leaf spring holder 28, 28A, 28B Linear shape memory alloy wire 28- 1-28-4 Inflection point (bending point)
281 First straight line part 282, 282A Second straight line part 283, 283A, 283B Connection part 283A1, 283B1 First connection straight line part 283A2, 283B2 Second connection straight line part 283A3 Third connection direct connection part 283B3 Connection circle Arc portion 31 First electrode 32, 32A Second electrode O Optical axis of lens AFL Autofocus lens θ1, θ2, θ3 Angle of inflection point

Claims (8)

A lens holder having a cylindrical portion for holding a lens barrel; a housing for supporting the lens holder so as to be movable only in the optical axis direction; a moving means for moving the lens holder in the optical axis direction; and the lens. In a lens driving device comprising a guide means for guiding the holder so as to be movable only in the optical axis direction,
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 the radial direction. ,
The moving means is formed of a linear shape memory alloy wire disposed near the outer wall of the cylindrical portion of the lens holder and engaged with the lens holder, and the shape memory alloy wire is at least one inflection. A lens driving device having a point.   The elastic member is composed of a pair of leaf springs provided on both sides in the optical axis direction of the cylindrical portion of the lens holder, and each of the pair of leaf springs is an inner peripheral side end portion attached to the lens holder. The lens driving device according to claim 1, further comprising an outer peripheral side end portion attached to the housing.   3. The lens driving device according to claim 1, wherein the lens holder has at least one protruding portion that protrudes radially outward from the cylindrical portion and engages with the shape memory alloy wire. The housing has an actuator base disposed on the lower side of the lens holder, and an upper cover that covers the lens holder from above,
4. The lens driving device according to claim 3, further comprising first and second electrodes fixed to the actuator base and electrically connected to first and second ends of the shape memory alloy wire, respectively. .   The lens driving device according to claim 4, wherein the shape memory alloy wire has one inflection point, and the angle of the inflection point is less than 90 °.   The lens driving device according to claim 4, wherein the shape memory alloy wire has a plurality of inflection points, and an angle of each inflection point is less than 45 °. The lens holder has first and second protrusions that protrude radially outward at positions facing each other from the cylindrical portion and engage with the shape memory alloy wire,
The first and second electrodes are respectively disposed at both ends of the actuator base,
The lens driving device according to claim 4, wherein the shape memory alloy wire includes an arc-shaped portion arranged in an arc shape along an outer wall of the cylindrical portion of the lens holder.   The lens driving device according to claim 7, wherein the shape memory alloy wire has a plurality of inflection points, and an angle of each inflection point is less than 90 °.

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