JP2008020811A - Lens driving mechanism and imaging apparatus using same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a large displacement amount while achieving miniaturization and reduction of weight in a lens driving mechanism to which an SMA actuator is applied. <P>SOLUTION: A link member is cut out from a sheet metal or an elastic polymer sheet and formed to be rhombic, consequently, formed so that a major axis H and a minor axis V may have relation of V/H<1. By bonding the link member 21 and another link member 22 at the ends in a major axis direction, winding and laying the SMA actuator 30 on the link members and contracting/loosing it, the two link members 21 and 22 are allowed to perform pantographic operation on the cross sections in the major axis direction. Thus, the large displacement amount is obtained while achieving the miniaturization and the reduction of weight. By forming the link member to be rhombic, space A1 for caulking the SMA 30 is secured around a lens unit 10 in a minor axis V direction, and also the lens unit 10 is prevented from dropping by restraining the warpage of four arms of the link members 21 and 22. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention is a relatively small imaging device mounted on a camera-equipped cellular phone or the like, and a lens that is suitably used for the imaging device and drives a lens unit constituting an imaging optical system for focus adjustment, zoom adjustment, and the like. The drive mechanism.

  In recent years, image quality has been improved, for example, the number of pixels of an image sensor mounted on a camera-equipped mobile phone or the like has increased dramatically. In accordance with this, there is a demand for higher performance of the lens unit constituting the imaging optical system. Specifically, an optical zoom is required for the auto focus type instead of the fixed focus type and for the zoom function instead of or in addition to the digital zoom. Here, a lens driving mechanism for moving the lens in the optical axis direction is required for both autofocus and optical zoom.

  Conventionally, a moving coil type is widely used as such a lens driving mechanism. This is achieved by attaching a pair of coils and magnets to a ball frame for fixing the lens and a stationary frame body for supporting the ball frame, and using a magnetic repulsive force that depends on the amount of current applied to the coil. The frame is driven in the optical axis direction. However, in this moving coil system, it is indispensable to use coils and magnets that are difficult to reduce in size, and this does not match the recent trend of reduction in size and weight. Further, since it is necessary to mount a heavy coil on the ball frame, there is a disadvantage that the ball frame has a large moment of inertia at the time of applying an impact and is inferior in impact resistance.

  As an alternative lens driving mechanism, one using a shape memory alloy (hereinafter sometimes referred to as SMA) actuator is known. This is a method in which a contraction force is generated by energizing and heating the SMA and the contraction force is used as a lens driving force. In general, it is easy to reduce the size and weight, and a relatively large force can be obtained. There is an advantage.

As a lens driving mechanism to which the SMA actuator is applied, for example, structures disclosed in Patent Documents 1 to 4 are known. Patent Document 1 discloses that an SMA spring and a bias spring are antagonistically arranged with a moving lens interposed therebetween. Patent Document 2 discloses a configuration in which an SMA wire is spirally wound around the outer periphery of a cam tube that guides a lens in the optical axis direction, and the cam tube is rotated by the contraction force of the SMA wire. Patent Document 3 discloses a configuration in which an SMA wire is bridged between a ball frame and a fixed portion, and the ball frame is moved by the contraction force of the SMA wire. Further, Patent Document 4 discloses a lens driving mechanism including a configuration in which the contraction force of the SMA wire is expanded by a gear mechanism.
JP-A-9-127398 JP-A-2005-195998 JP 2002-130114 A Japanese Patent Application Laid-Open No. 2005-156892

  Generally, the amount of contraction displacement obtained by energizing and heating SMA is only about a few percent of the total length. In consideration of the durability, it is necessary to drive the SMA tightly within a displacement range of about 3% at most. For this reason, in the method in which the lens (ball frame) is directly driven by the SMA actuator as in the configurations of Patent Documents 1 to 3, the amount of movement of the lens is relatively small, and high-performance autofocus and optical zoom Therefore, there is a problem that a necessary lens movement amount cannot be obtained. Moreover, although the amount of displacement can be obtained by using the configuration of Patent Document 4, the mounting of the gear mechanism becomes an obstacle to reducing the size and weight.

  The present invention has been made in view of the above circumstances, and in a lens driving mechanism to which an SMA actuator is applied, a lens driving mechanism capable of obtaining a large displacement while achieving a reduction in size and weight, and an imaging apparatus using the same. The purpose is to provide.

  The lens driving mechanism of the present invention is a lens driving mechanism comprising: a lens unit; and a driving unit that moves the lens unit in the optical axis direction by applying a driving force from the outer side of the lens unit. The drive means includes two link members formed by connecting four arms in a rhombus shape so that the lens unit is housed therein, and a corner portion in the major axis direction of the two link members. A joining means for joining and a linear shape memory alloy actuator wound between corners in the major axis direction of the link member, and the corners in the major axis direction of the two link members are input of driving force. The corner portion in the minor axis direction becomes the output end of the driving force, and the linear shape memory alloy actuator contracts / relaxes so that the corner portions in the minor axis direction are separated / proximately displaced from each other. , The lens unit which is suspended between the corners of the minor axis of the square of the link member is thus being moved in the optical axis direction.

  According to the above configuration, in the lens driving mechanism that realizes focus adjustment and zoom adjustment by moving the lens unit in the optical axis direction by applying a driving force from the outer side of the lens unit, the driving unit Is provided with two link members, a joining means, and a linear shape memory alloy actuator, and each of the two link members is configured such that four arms house the lens unit therein. The corners in the major axis direction are joined to each other by the joining means, and the lens unit is suspended between the corners in the minor axis direction of one link member, and the shape memory The alloy actuator is wound around a corner portion in the major axis direction of the two link members. Accordingly, the two link members can be expanded and contracted in a pantograph shape when viewed in a cross section in the major axis direction. The corner portion in the minor axis direction of the other link member may be used to push up the lens unit suspended on the one link member in contact with the base, and at the position of the shape memory alloy actuator. The lens driving mechanism may be mounted on a base, and a light receiving element may be suspended between corners in the minor axis direction of the other link member.

  Therefore, the corner portion in the major axis direction of the two link members becomes the input end of the driving force, and when the shape memory alloy actuator contracts, the corner portion in the minor axis direction that becomes the output end of the driving force is mutually connected. The pantograph-shaped link member expands and pushes out the lens unit. On the other hand, when the shape memory alloy actuator is relaxed, the corners in the minor axis direction are displaced closely to each other, and the pantograph-like link member is reduced to pull down the lens unit. Thus, using the linear shape memory alloy actuator, it is possible to obtain a large amount of displacement of the lens unit in the optical axis direction while achieving a reduction in size and weight.

  In addition, since the shape in the direction orthogonal to the optical axis of the two link members is formed in a rhombus shape, each corner portion is not a right angle, and the major axis H and the minor axis V are V / H < 1 relationship. Accordingly, a space for caulking the linear shape memory alloy actuator can be secured around the lens unit in the minor axis V direction with respect to the rectangular base. As a result, even if solder cannot be used because the memory disappears due to temperature, and the wire shape is thin, even if the adhesive cannot be used because the generated tension is high, the linear shape memory can be used. The drive means can be configured as described above using an alloy actuator.

  Furthermore, as described above, the shape in the plane orthogonal to the optical axis of the two link members is formed in a rhombus, and the corner portion in the major axis direction becomes the input end of the driving force, so that the minor axis direction The amount of movement of the lens unit can be increased even when the shape memory alloy actuator expands and contracts by the same length as compared with the case where the corner portion of the lens becomes the input end, The moment applied to the outer side can be reduced, and when the shape memory alloy actuator is contracted, the corners in the minor axis direction of the two link members are separated from each other in the optical axis direction. Further, it is possible to suppress the warp of the arm and to prevent the lens unit from falling off from the corner portion in the short diameter direction.

  In the lens driving mechanism of the present invention, the link member is formed in a plate shape, and the corner portion in the minor axis direction is formed narrower than the surroundings.

  According to said structure, the said link member can suppress local stress concentration by being formed in plate shape. However, there is a possibility that the arm becomes too easy to bend in the thickness direction as a whole, and the amount of separation displacement between the corner portions in the minor axis direction when the shape memory alloy actuator is contracted may be reduced. Therefore, by forming a notch or slit in the corner portion in the minor axis direction and forming a width narrower than the surroundings, the corner portion in the minor axis direction is formed. Becomes easier to bend, and the bending of the arm can be suppressed.

  In this way, while suppressing local stress concentration on the arm and the corner that is the connection point thereof, the bending of the arm is suppressed and the corners in the minor axis direction of the two link members are separated as much as possible. The driving force of the shape memory alloy actuator can also be used effectively.

  Furthermore, in the lens driving mechanism of the present invention, the portion where the width is narrower than the surroundings in the corner portion in the minor axis direction is formed by a notch or slit formed in the minor axis direction, At least one of the suspension piece of the lens unit mounted on the corner portion of the minor axis direction in the link member and the contact portion of the base on which the corner portion of the minor axis direction contacts the other link member, Protrusions that fit into the notches or slits are formed.

  According to the above configuration, even if the shape memory alloy actuator formed linearly as described above expands and contracts in the circumferential direction of the lens unit, the slit or slit formed in the corner portion in the minor axis direction Since the convex portion formed on at least one of the suspension piece of the lens unit and the contact portion of the base is fitted, the rotation of the link member can be prevented.

  According to another aspect of the present invention, there is provided an imaging apparatus comprising: the lens driving mechanism; an imaging element disposed on an image plane side of the lens unit; and a control unit that controls the operation of the lens driving mechanism. .

  According to the above configuration, the linear shape memory alloy actuator can be used to achieve a small displacement and a large amount of displacement in the optical axis direction of the lens unit while at the same time, and the drive means is configured. It is possible to realize an imaging apparatus that can suppress the warp of the arm and make it difficult for the lens unit to fall off.

  As described above, the lens driving mechanism of the present invention moves the lens unit in the optical axis direction by applying a driving force from the outer side of the lens unit, and realizes focus adjustment and zoom adjustment. In the mechanism, the drive means includes two link members that are connected in a diamond shape so that four arms accommodate the lens unit therein, and the corners in the major axis direction of the two link members. And a linear shape memory alloy actuator wound between corner portions in the major axis direction of the link member, and a corner angle in the major axis direction of the two link members. The linear shape memory alloy actuator contracts / relaxes with the corners in the minor axis direction as the driving force output ends and the linear shape memory alloy actuator contracts / relaxes. To perform the Jo of the expansion displacement causes the lens unit which is suspended between the corners of the minor axis of one link member is moved in the optical axis direction.

  Therefore, it is possible to obtain a large displacement amount of the lens unit in the optical axis direction while achieving a reduction in size and weight by using a linear shape memory alloy actuator. In addition, since the shape in the direction orthogonal to the optical axis of the two link members is formed in a rhombus, each corner is not a right angle, and in the minor axis direction, the linear shape is formed around the lens unit. Space for caulking the shape memory alloy actuator can be secured, and memory disappears due to temperature, so even if solder can not be used, and because the tension generated in the thin wire diameter is high, the adhesive Even if this is not possible, the drive means can be configured as described above using a linear shape memory alloy actuator. Furthermore, as described above, the shape in the plane orthogonal to the optical axis of the two link members is formed in a rhombus, and the corner portion in the major axis direction becomes the input end of the driving force, so that the minor axis direction The amount of movement of the lens unit can be increased even when the shape memory alloy actuator expands and contracts by the same length as compared with the case where the corner portion of the lens becomes the input end, The moment applied to the outer side can be reduced, and when the shape memory alloy actuator is contracted, the corners in the minor axis direction of the two link members are separated from each other in the optical axis direction. Further, it is possible to suppress the warp of the arm and to prevent the lens unit from falling off from the corner portion in the short diameter direction.

[Embodiment 1]
FIG. 1 is a perspective view showing main components of an imaging apparatus 2 including a lens drive module 1 which is a lens drive mechanism according to an embodiment of the present invention, FIG. 2 is an exploded perspective view thereof, and FIG. It is the longitudinal cross-sectional view. The lens driving module 1 generally holds the lens unit 10, link members 21 and 22 and SMA actuators 30 as driving means for moving the lens unit 10 in the optical axis AX direction, and the lens unit 10. Spring members 41 and 42 and a bias spring 43 are provided. On the image plane side of the lens unit 10, an image sensor 3 for photoelectrically converting a subject light image is disposed.

  The spring members 41 and 42 are upper bases that are fixed positions so as to allow the lens unit 10 to move in the optical axis AX direction while preventing the lens unit 10 from moving in the direction intersecting the optical axis AX direction. 51 and a lower base 52 are provided in a pair of front and rear. The bias spring 43 prevents the lens unit 10 from popping out due to excessive contraction at a high temperature of the SMA actuator 30, which will be described later, and differs depending on the tension to which the temperature at which the SMA actuator 30 reacts is applied. It is interposed between a front panel and the like (not shown) so as to contract by a predetermined amount due to heat generation at a constant temperature.

  As shown in FIG. 2, the lens unit 10 has a lens frame 12 in which a photographic lens 11 is fitted, and a generally cylindrical shape. And a lens barrel 13 to which the lens 11 can be attached. The ball frame 12 is attached by holding a notch 14 with a tool or the like and screwing an external screw engraved on the outer peripheral surface of the notch 14 into an inner screw engraved on the inner peripheral surface of the lens barrel 13. The photographing lens 11 includes an objective lens, a focus lens, a zoom lens, and the like, and constitutes an imaging optical system for subject images with respect to the image sensor 3.

  On the front end side of the lens barrel 13, a pair of suspension pieces 15 extending outward in the radial direction are formed from a position on one diameter line. With the suspension pieces 15, the lens unit 10 is connected to the link member 21. Engaged (supported). On the rear end side of the lens barrel 13, a pair of guide ridges 16 extending in the optical axis AX direction are formed at positions on the diameter line orthogonal to the diameter line on which the suspension piece 15 is formed.

  The link members 21 and 22 are connected pieces 21e, 21f; 22e, 22f so that the four arms 21a, 21b, 21c, 21d; 22a, 22b, 22c, 22d accommodate the lens unit 10 therein. It is connected to the rhombus. The material of the link members 21 and 22 is not particularly limited, and has the strength capable of transmitting the driving force, while the arms 21a, 21b; 21c, 21d; 22a, 22b; 22c, 22d and the connecting piece 21e. 21f; 22e; 22f; and the joints between arms 21a, 21c; 21b, 21d; 22a, 22c; 22b, 22d may be members that can elastically deform and serve as a node. For example, a thin metal plate or an elastic polymer sheet can be cut out and formed by bending. In particular, a resin material having a low bending elastic modulus so that the loss of force due to elastic deformation at the node is small, a high bending strength so that it is difficult to break due to elastic deformation, and excellent heat resistance is desirable. As such a resin material, polycarbonate or polyethylene terephthalate can be used. When these resin materials are used, it is not necessary to consider an electrical short circuit or heat escape by the link members 21 and 22 with respect to the contact with the SMA actuator 30.

  The link members 21 and 22 are connected to each other by connecting pins 21e and 21f; 22e and 22f, which are corner portions in the major axis direction, by pins 23 which are connecting means, and the SMA actuator is connected to the pins 23. 30 is wound to form a displacement input unit to which an input of driving force in a direction orthogonal to the optical axis AX is given. Based on the driving force applied to the displacement input portion, the link members 21 and 22 are pantograph-like operations in the cross section in the long diameter direction, as shown in FIG. 3, and are corner portions in the short diameter direction. The connecting points 21g, 21h; 22g, 22h of the arms 21a, 21c; 21b, 21d; 22a, 22c; 22b, 22d serve as displacement output units that move in the optical axis AX direction. The suspension piece 15 of the lens unit 10 is mounted on the connection points 21 g and 21 h of the one link member 21, and the connection points 22 g and 22 h of the other link member 21 are mounted on the intermediate base 53.

  Notches 21i and 22i are formed in the connecting points 21g and 21h; 22g and 22h from the inner side. Instead of these notches 21i and 22i, a slit or the like extending in the minor axis direction may be formed. A protrusion 15 a formed on the suspension piece 15 is fitted into the notch 21 i of the link member 21 to prevent the lens unit 10 from shifting in the major axis direction. In the case where the notch 21i is formed from the outer side to the inner side, and in the case of a slit, the lens unit 10 can be reliably prevented from falling off. Similarly, a protrusion 53a formed on the intermediate base 53 is fitted into the notch 22i of the link member 22, and the displacement of the link member 22 in the major axis direction is prevented.

  The SMA actuator 30 is a line actuator made of a shape memory alloy (SMA) wire (single linear body) such as a Ni-Ti alloy. The SMA actuator 30 expands when given a predetermined tension at a low temperature and a low elastic modulus (martensite phase). When heat is applied in this extended state, the SMA actuator 30 undergoes phase transformation and a high elastic modulus (austenite). Phase (matrix) and return to its original length (recover shape) from the stretched state.

  In this embodiment, the structure which performs the above-mentioned phase transformation by energizing and heating the SMA actuator 30 is employ | adopted. That is, since the SMA actuator 30 is a conductor having a predetermined resistance value, Joule heat is generated by energizing the SMA actuator 30 itself, and transformation from the martensite phase to the austenite phase is performed by self-heating based on the Joule heat. It is supposed to be configured. For this reason, both ends of the SMA actuator 30 are caulked and fixed by caulking fittings 31a and 32a, which will be described later, serving as electrodes for energization heating.

  FIG. 4 is an enlarged cross-sectional view showing the vicinity of the joint between the two link members 21 and 22. Although FIG. 4 shows the structure between the connecting pieces 21f and 22f, the same structure is also applied between the connecting pieces 21e and 22e. In these connecting pieces 21e, 21f; 22e, 22f, recesses 21j, 22j are formed by a diaphragm, and one link member 21 has a hole 21k formed by punching in the bottom surface of the recess 21j. Yes. The pin 23 is inserted through the hole 21k, and then the head 23a and the peripheral portion of the hole 21k are heat welded using a laser, an ultrasonic wave, a heater, or the like, and then inserted through the hole 21k. The link member 21 and the link member 2 are assembled into the pantograph shape by bonding or heat-welding the tip 23b to the bottom surface 22k of the recess 22j. At this time, the connecting pieces 21e, 21f and the connecting pieces 22e, 22f are parallel to each other, for example, with an interval of 0.4 to 0.5 mm.

  The link members 21 and 22 assembled in this way are mounted on the intermediate base 53 so that the projection 53a fits into the notch 22i. At this time, as shown in FIG. 5, the intermediate base 53 supports a plurality of supports 54 for mounting and supporting the upper base 51, supports 31 and 32 for stretching both ends of the SMA actuator 30, and a midpoint. A supporting column 33 is erected. Since the SMA actuator 30 is wound around the column 32 from the column 31 via the pin 23 on the connection piece 21e, 22e side, the column 33, and the pin 23 on the connection piece 21f, 22f side, the column 31-33 has the rhombus shape. It is erected at a position in the minor axis direction.

  Thereafter, instead of the lens unit 10, a jig is fitted into the hole 53b formed in the intermediate base 53, and the link members 21 and 22 are placed in a predetermined state at the positions of the notches 21i and 22i. (So that the height of the pantograph becomes a constant height), the SMA actuator 30 is spanned along the path, and the caulking brackets 31a, 32a at the ends of the columns 31, 32 at both ends are caulked. As a result, the SMA actuator 30 is stretched with a certain length and tension.

  Subsequently, the jig is removed from the intermediate base 53, and a lower base 52 to which a spring member 42 and an image pickup device 3 as described later are attached is attached. Thereafter, the lens unit 10 to which the bias spring 43 is attached is inserted into the hole 53a, and the rear end portion is bonded to the spring member 42.

  Subsequently, the upper base 51 to which the spring member 41 is attached is attached on the column 54, and the front end portion of the lens unit 10 is bonded to the spring member 41, whereby the lens driving module 1 is completed. For example, as shown in FIG. 6, the upper base 51 is formed with a hole 51 a into which the lens unit 10 is loosely inserted and a hole 51 b which is connected to the hole 51 b and into which the suspension piece 15 is loosely inserted.

  Referring to FIGS. 5 and 3, the intermediate base 53 eliminates the difference between the length required for the lens unit 10 and the stroke of the pantograph operation as described above by the link members 21 and 22. Are suitably provided on the lower base 52 on which the image sensor 3 is mounted. In the present embodiment, by utilizing the provision of the intermediate base 53, as shown in FIG. 2 described above, a pair of lenses extending in the optical axis AX direction on the rear end side of the lens barrel 13 of the lens unit 10 is provided. Guide ridges 16 are formed. Correspondingly, the intermediate base 53 has a hole 53b in which the rear end side of the lens barrel 13, which is a part of the projection surface side of the lens unit 10, is retracted. A pair of guide concave grooves 53c extending in the direction of the optical axis AX is formed.

  As a result, when the lens frame 12 which is a lens portion is screwed into the front side of the lens barrel 13 which is a cylindrical body as described above, rotation of the lens barrel 13 around the optical axis AX is prevented, and the lens unit 10 is The range of elastic deformation of the suspended spring members 41 and 42 can be suppressed, and any photographing lens 11 can be attached using a common drive mechanism, so that versatility with respect to the photographing lens 11 can be improved. Moreover, impact resistance can also be improved. Furthermore, the spring members 41 and 42 can be made softer than before to improve the stroke or can be miniaturized. Further, the guide ridges 16 and the guide grooves 53c are positioned in the lens unit 10 on the diameter line on which the suspension piece 15 is formed, that is, the diameter line orthogonal to the rhombic minor axis direction, and thus the diameter line in the major axis direction. Therefore, the space can be secured relatively easily in a portion close to the lens unit 10. Furthermore, since the guide ridge 16 and the guide groove 53c are provided in a pair at symmetrical positions with the center of gravity of the lens unit 10 interposed therebetween, the fitting between the guide ridge 16 and the guide groove 53c is as follows. The lens unit 10 can be stably moved so as not to tilt from the optical axis AX.

  When the intermediate base 53 is not provided due to the relationship between the length of the lens unit 10 and the stroke of the pantograph operation as described above, a dedicated pillar is erected from the lower base 52 and the pillar is Alternatively, the guide groove 53c may be formed. However, when the intermediate base 53 is provided, the pillar can be used also by the intermediate base 53, and the outer peripheral surface of the lens unit 10 is guided by the hole 53b so that the lens unit 10 can be pivoted. It can be moved without misalignment (translation). Further, the guide protrusion 16 may be provided in the hole 53 b of the intermediate base 53, and the guide groove 53 c may be provided in the lens barrel 13.

  The spring members 41 and 42 are configured as shown in FIGS. FIG. 7 is a perspective view showing a state in which the biasing force by the bias spring 43 is not applied to the spring member 41, and FIG. 8 is a plan view thereof. 7 and 8, the spring member 41 will be described, but the spring member 42 is similarly configured. The spring member 41 is formed in an annular shape so as to contain the lens unit 10, and the opposed position 41 a spaced apart by 180 ° in the circumferential direction is the upper base 51 (spring member 41) or the lower base 52 ( A first annular portion 41b fixed at a fixed position of the spring member 42), a second annular portion 41c formed along the first annular portion 41b, and the position in the first annular portion 41b. A connecting piece 41e for connecting a midpoint 41d between 41a to the second annular portion 41c, and a suspension for extending the lens unit 10 extending from a midpoint 41f between the connecting pieces 41e in the second annular portion 41c. And 41 g.

  That is, in the spring member 41, two annular portions 41b and 41c containing the lens unit 10 are connected by a connecting piece 41e, and a suspension piece 41g is extended from two points 41f of the second annular portion 41c. The unit 10 is suspended, and the positional relationship between the respective parts is that the first annular portion 41b is fixed at the fixed position at the opposed position 41a spaced apart by 180 ° in the circumferential direction, and the connecting piece 41e. Is provided at a midpoint 41d between the fixed positions (41a) in the first annular portion 41b, and the suspension piece 41g is extended from a midpoint 41f between the connecting pieces 41e in the second annular portion 41c. The Therefore, the connecting piece 41e and the suspension piece 41g are located at the same angular position on the circumference, and one suspension piece 41g is a first annular portion extending in a substantially opposite direction from the fixed position (41a). It will be supported by a pair of spring members which consist of the 2nd annular part 41c which returned from 41b by the connection piece 41e and returned to the said fixed position (41a) side.

  As a result, the connecting piece 41e and the suspension piece 41g approach / separate, so that the lens unit 10 can be supported even if it moves in the optical axis AX direction. However, no rotational force in the circumferential direction of the lens unit 10 is generated, and the lens unit 10 can always be moved in parallel with the optical axis AX and without misalignment of the axis. In general, in the case of a plate spring member having such a long stroke, in order to improve the impact resistance, it is necessary to increase the plate thickness or the plate width. The translation of the lens unit 10 is suppressed by fitting the rear end side of the tube 13 into the hole 53b of the intermediate base 53, and the guide protrusion 16 is fitted into the guide groove 53c. Since rotation in the circumferential direction is prevented, impact resistance is ensured, and it is not necessary to increase the plate thickness or increase the plate width as described above.

  In the above example, the first annular portion 41b and the second annular portion 41c are formed in a rectangular shape, but may be in a circular shape or the like. However, if it is a rectangle, the space on the rectangular bases 51 and 52 can be utilized to the maximum, and the spring stroke can be earned.

  The bias spring 43 urges the lens unit 10 in a direction opposite to the direction in which the lens unit 10 is moved by the operation (constriction) of the SMA actuator 30 and substantially matches the peripheral size of the lens frame 12. The one end side (the lower end side) is in contact with the top surface of the ball frame 12. The other end side (upper end side) of the bias spring 43 comes into contact with, for example, the inner surface of the housing of the mobile phone.

  The amount of force of the bias spring 43 is weaker than the driving force by the SMA actuator 30. That is, when the SMA actuator 30 is not operating, the lens unit 10 is pressed toward the lower base 52 (downward in FIG. 3), and applies a certain tension to the SMA actuator 30 as described above. When the SMA actuator 30 operates, the lens unit 10 is moved in the opposite direction (upward in FIG. 3) against the pressing force of the bias spring 43. In other words, the bias spring 43 provides the lens unit 10 with a bias force for returning the lens unit 10 to the home position after the operation of the SMA actuator 30 is completed. By assembling the bias spring 43, a bias force is always applied to the lens unit 10, so that the lens unit 10 can be returned to the home position by controlling the energization amount to the SMA actuator 30, and drive control can be performed. It becomes easy to do.

  The image pickup device 3 photoelectrically converts and outputs R, G, and B component image signals in accordance with the amount of light of the optical image of the subject imaged by the lens unit 10. For example, the image sensor 3 has R (red), G (green), and B (blue) color filters on the surface of each CCD of an area sensor in which a CCD (Charge Coupled Device) is two-dimensionally arranged. It is possible to use a single plate type color area sensor which is a so-called Bayer method and is attached in a checkered pattern. In addition to such a CCD image sensor, a CMOS image sensor, a VMIS image sensor, or the like can also be used.

  Next, the mechanical operation of the lens driving module 1 configured as described above will be described. FIG. 9 is a plan view showing the link members 21 and 22 and the SMA actuator 30 extracted, and FIG. 10 is a side view thereof. Referring to FIG. 3 as well, when a predetermined voltage is applied between the caulking fittings 31a and 32a serving as both electrodes of the SMA actuator 30 and the SMA actuator 30 is heated to be transformed to the austenite phase by energization, the SMA actuator 30 Produces an austerity. This contraction force acts on the pin 23 which becomes a displacement input part of the link members 21 and 22 over which the SMA actuator 30 is bridged. That is, the moving forces F1 and F2 from the outer direction opposite to each other by 180 degrees toward the center of the optical axis AX are applied between the pins 23.

  In response to the moving forces F1 and F2, the link members 21 and 22 are deformed so that the height dimension expands in the direction of the optical axis AX, and performs the pantograph type operation as described above. That is, the joints of the arms 21a, 21b; 21c, 21d; 22a, 22b; 22c, 22b and the connecting pieces 21e; 21f; 22e; 22f and the arms 21a, 21c; 21b, 21d; The link members 21 and 22 are deformed so that the joint portions 22b and 22d are bent by the moving forces F1 and F2 and the distance between the connection points 21g and 22g; 21h and 22h is expanded. Here, since the connection points 22g and 22h of the second link member 22 are mounted on the intermediate base 53, only the connection points 21g and 21h of the first link member 21 constituting the displacement output unit are provided. A moving force F3 that expands toward the object side along the optical axis AX is generated.

  The moving force F3 is transmitted from the connection points 21g and 21h to the lens unit 10 through the suspension piece 15, and the lens unit 10 is displaced in the optical axis AX direction (state shown in FIG. 3). At this time, the annular portions 41b and 41c (the same applies to the spring member 42) of the spring members 41 and 42 warp upward (object side), and the bias spring 43 is in a compressed state.

  When energization to the SMA actuator 30 is stopped (or the voltage is reduced to a predetermined value) and the SMA actuator 30 is cooled and returned to the martensite phase, the moving force F1 applied between the pins 23 serving as the displacement input portion F2 disappears. Then, the biasing force of the bias spring 43 returns the lens unit 10 to the home position along the optical axis AX direction. In this way, the lens unit 10 can be displaced along the optical axis AX direction by energizing the SMA actuator 30 on and off. Further, the amount of displacement of the lens unit 10 can be adjusted by controlling the energization current to the SMA actuator 30 to adjust the force of the moving forces F1 and F2.

  Here, in the present embodiment, one SMA actuator 30 uses two pins 23 and one column 33 arranged between these pins 23 with the columns 31 and 32 as a base point. It is constructed in a quadrangular shape along the outer periphery of the link members 21 and 22. Therefore, the intermediate point of the entire length of the SMA actuator 30 is supported by the support 33 serving as a tension guide, and the pins 23 are positioned between the support 33 and the support 31 and between the support 33 and the support 31. ing.

  For this reason, since the SMA actuator 30 expands and contracts by the same amount of displacement at half intervals from the support column 33, the SMA actuator 30 is not rubbed at the support portion (contact portion) by the support column 33. Similarly, the SMA actuator 30 is hardly rubbed even in the support portion by the pin 23 because the expansion and contraction is performed with substantially the same amount of displacement even with each half of the pin 23 as a boundary. Therefore, the loss of power due to rubbing is minimized, and damage to the SMA actuator 30 due to friction is prevented. In addition, since there is no sliding part or gear meshing part, the number of parts is small, the occurrence of backlash and the like can be avoided, and furthermore, backlash does not occur, so the response of the lens unit 10 is smooth with good output efficiency. Drive can be performed.

  Further, according to the link members 21 and 22 of the present embodiment, the displacement due to the contraction of the SMA actuator 30 is enlarged in two stages and transmitted to the displacement output unit. That is, by assembling the link members 21 and 22 and the SMA actuator 30 as described above, a displacement larger than the actual amount of contraction of the SMA actuator 30 can be input to the link members 21 and 22 (one step of the displacement expanding function). In addition, the displacement can be further expanded by the link members 21 and 22 (second stage of the displacement expansion function). Thereby, although the amount of contraction of the SMA actuator 30 is several percent of the total length, a large displacement can be given to the lens unit 10. Hereinafter, these displacement enlargement functions will be described in detail.

[1] First Stage of Displacement Enlargement Function FIG. 11 is a schematic diagram showing the relationship between the tight displacement of the SMA actuator 30 and the displacement of the link members 21 and 22. As shown in FIG. 11A, in the initial state where the SMA actuator 30 is not energized, the SMA actuator 30 is in a state indicated by a solid line in the figure. On the other hand, when energized and heated, a contracted state 30S indicated by a dotted line in the figure is obtained. Reference numerals P1 and P3 in the figure indicate installation points to the pins 23, respectively, and reference numeral P2 indicates an installation point to the column 33. In this case, the SMA actuator 30 does not move at the point P2, but at the points P1 and P3, the displacement is input by the distance a on one side.

  FIG. 11B is a circle drawn with the distance from the point P2 to the point P1, which is the displacement input unit, as a radius. The solid line circle 35 indicates a state where the SMA actuator 30 is not contracted, and the dotted line circle 35S indicates a contraction. Each state is shown. In this case, the actual amount of contraction of the SMA actuator 30 is a distance d along the radial direction (the difference in radius between the solid line circle 35 and the dotted line circle 35S). However, the moving distance a of the point P1 is larger than the distance d. That is, it is understood that a displacement larger than the actual contraction amount of the SMA actuator 30 can be input at the points P1 and P3.

  This is because the SMA actuator 30 is bent at the point P1, which is an intermediate point from the support 31 to the point P2, and the contraction force is not in the overhead direction of the SMA actuator 30, but in the center direction of the bending angle (that is, the optical axis AX). By acting in the center direction). It is understood that the displacement input amount increases as the tension angle θ of the SMA actuator 30 decreases, as indicated by the movement distance a ′ and the movement distance a ″ in the drawing.

[2] Second Stage of Displacement Enlarging Function The link members 21 and 22 as shown in FIG. 10 can be regarded as a four-joint link mechanism having an arm 200 of equal length r as shown in FIG. it can. As indicated by the solid line, when an inclination angle of the arm 200 is θ ₀ , when an input displacement b directed from the portion corresponding to the left and right nodes (the pin 23 serving as a displacement input unit) toward the center in the left-right direction is given, 200 tilts as indicated by a dotted line 200F, and the tilt angle changes to θ _f larger than θ ₀ . As a result, an output displacement c is generated at the upper and lower nodes.

13A to 13C are diagrams schematically showing the relationship between the input displacement b and the output displacement c. 13 (a) is a tilt angle theta ₁₁ in the initial state of the arm 200 indicated by the solid line, tilt center angle theta ₁₃ between the tilt angle theta ₁₂ of the arm 200F after displacement indicated by the dotted line is a [pi / 4 Shows the case. In other words, the tilt angle theta ₁₁ of the arm 200 in the initial state, the inclination angle theta ₁₂ of the arm 200F after displacement, even when a target around the [pi / 4, it can be expressed by the following formula .

θ ₁₂ −θ ₁₃ (π / 4) = θ ₁₃ (π / 4) −θ ₁₁
In this case the tilt center angle theta ₁₃ is [pi / 4, the displacement of the upper and lower sections relative to the displacement of the left and right section 1: 1. Therefore, the input displacement b ₁ and the output displacement c ₁ are equal. Therefore, in this case, the displacement enlargement function cannot be obtained.

On the other hand, in FIG. 13B, the inclination central angle θ ₂₃ between the inclination angle θ ₂₁ in the initial state of the arm 200 indicated by the solid line and the inclination angle θ ₂₂ of the arm 200F after the displacement indicated by the dotted line is π The case where it is smaller than / 4 is shown. In this case, output displacement c ₂ for the input displacement b ₂ as shown is enlarged. That is, the relationship of input displacement b ₂ <output displacement c ₂ is established.

On the other hand, FIG. 13C shows that the tilt central angle θ ₃₃ between the tilt angle θ ₃₁ in the initial state of the arm 200 indicated by the solid line and the tilt angle θ ₃₂ of the arm 200F after the displacement indicated by the dotted line is π / The case where it is larger than 4 is shown. In this case, output displacement c ₃ to the input displacement b ₃ as shown is reduced. That is, the relationship of input displacement b ₂ > output displacement c ₂ is established.

  From the above, by setting the inclination angle of the arm 200 in the link members 21 and 22 as shown in FIG. 13B, the displacement expanding function can be obtained in the link members 21 and 22. In actual assembly, considering the stroke required for focusing and zooming of the lens unit 10, the inclination angle of the arm 200 when the lens unit 10 is at the home position (inclination angle with respect to a line connecting the two displacement input portions) and The displacement enlargement function can be obtained by setting the inclination central angle between the inclination angle of the arm 200 when moved to the maximum to be π / 4 or less.

  Note that the smaller the tilt angle, the greater the displacement expansion function, but the smaller the output force. That is, the driving power of the lens unit 10 decreases. For this reason, it is not preferable to make the inclination center angle too small, and the ratio of the input displacement b to the output displacement c is about 1: 1.5 to 7, preferably 1: 3 in consideration of power and displacement. It is desirable to select the tilt center angle so as to be about ˜6.

  As described above, the link members 21 and 22 according to the present embodiment have a two-stage displacement expansion function, and the displacement input unit is given a first displacement amount larger than the displacement of the SMA. In this case, a second displacement amount larger than the first displacement amount can be output from the displacement output unit. Thereby, the lens unit 10 can be given a displacement that is two steps larger than the actual displacement of the SMA actuator 30. Therefore, even if the displacement amount of the SMA actuator 30 is small, it is possible to obtain a lens movement amount necessary for autofocus and optical zoom.

  Further, in order to obtain the displacement expansion function as described above, the link members 21 and 22 are formed in a diamond shape as described above, so that each corner is not a right angle as shown in FIG. The minor axis V has a relationship of V / H <1. Therefore, a space A1 for caulking the SMA actuator 30 can be secured around the lens unit 10 in the minor axis V direction with respect to the rectangular bases 52 and 53. The space A1 is, for example, about φ = 2 mm with respect to V = 10 mm and the outer diameter of the lens unit 10 = 6 mm. As a result, the SMA actuator 30 is used even if the solder cannot be used because the memory disappears due to temperature, or the adhesive is not usable because the generated tension is high despite the thin wire diameter. Thus, the link members 21 and 22 can be driven as described above.

  Furthermore, as described above, the shape of the two link members 21 and 22 in the plane orthogonal to the optical axis AX is formed in a rhombus shape, and the pin 23 at the corner in the major axis direction is the input end of the driving force. As a result, the SMA actuator 30 is expanded and contracted by the same length as described in detail earlier than when the connecting points 21g, 21h; 22g, 22h are input ends which are corners in the minor axis direction. In addition, the amount of movement of the lens unit 10 can be increased, and the moment applied to the arms 21a, 21c; 21b, 21d; 22a, 22c; , And the connecting points 21g, 21h; 22g, 22h are mutually in the direction of the optical axis AX when the SMA actuator 30 is contracted. Order to counter-displaced, arms 21a, 21c; 21b, 21d; 22a, 22c; 22b, suppressing the warp of 22 d, the suspension piece 15 the connection point 21g of the lens unit 10 can be less likely to fall off from 21h.

  Further, the link members 21 and 22 are formed in a plate shape, so that local stress concentration can be achieved as in the case where ribs are provided on the arms 21a, 21c; 21b, 21d; 22a, 22c; 22b, 22d. Can be suppressed. However, the arm arms 21a, 21c; 21b, 21d; 22a, 22c; 22b, 22d are too easy to bend in the thickness direction as a whole, and the connection points 21g, 21h; 22g, 22h when the SMA actuator 30 contracts. There is a possibility that the distance between them will be less. Therefore, by forming notches 21i, 22i in the connecting points 21g, 21h; 22g, 22h and making the width narrower than the surroundings, the connecting points 21g, 21h; 22g, 22h are more easily bent, and the arms 21a, 21c; 21b, 21d; 22a, 22c; 22b, 22d can be prevented from bending. In this way, the arms 21a, 21c; 21b, 21d; 22a, 22c; 22b, 22d and the connecting pieces 21e, 21f; 21b, 21d; 22a, 22c; 22b, 22d can be restrained so that the connecting points 21g, 21h; 22g, 22h of the two link members 21, 22 are separated as much as possible, and the SMA actuator 30 is driven. Power can be used effectively.

  Furthermore, when the corner portions of one diagonal line of the two sheet-like link members 21 and 22 are simply bonded, the corner portions are buckled by the tension of the wound SMA actuator 30. When the driving force of the SMA actuator 30 cannot be successfully converted into the moving force of the lens unit 10, the corner portions of the two link members 21 and 22 are joined via a pin 23 with a predetermined interval. By doing so, buckling of the corner portion can be suppressed, and also by this, the driving force of the SMA actuator 30 can be efficiently converted into the moving force of the lens unit 10. Furthermore, since the predetermined interval is provided, there is an effect that the SMA actuator 30 can be easily suspended.

  Further, as shown in FIG. 4, holes 21 k through which pins 23 are inserted are formed in the connecting pieces 21 e and 21 f which are corners in one diagonal direction in one link member 21, and the corresponding in the other link member 22. In the connecting pieces 22e and 22f, which are corner portions, a recess 22j that receives the tip 23b of the pin 23 is formed by a throttle, and the head portion 23a of the pin 23 that is inserted through the hole 21k is the peripheral portion of the hole 21k. Since the link members 21 and 22 are assembled by joining the tip 23b to the recess 22j, the link members 21 and 22 can be assembled from one direction, and the pin 23 is electrically assembled. By using an insulating material, it is possible to use conductive members for the link members 21 and 22. Further, the pin 23 can be positioned by the recesses 21j and 22j, and the assembly can be easily performed.

  Furthermore, as shown in FIGS. 3 and 9, when the link members 21 and 22 are expanded to the pantograph type, the SMA actuator 30 is stretched obliquely from the support columns 31 and 32 at fixed positions. On the other hand, in the connecting pieces 22e and 22f of the link member 22 on the side close to the SMA actuator 30, a protrusion 22x lower than the height of the pin 23 is formed in a path on which the SMA actuator 30 is stretched. Has been. Thereby, even if the pantograph is enlarged, the SMA actuator 30 can be reliably prevented from sliding down.

  Further, as shown in FIGS. 9 and 10, the connecting pieces 21e, 21f; 22e, 22f of the link members 21, 22 are parallel to each other, and are connected to the inner peripheral edges of the connecting pieces 21e, 21f; 22e, 22f. Since the pin 23 is erected on the other side, the SMA actuator 30 can be reduced in size as compared with the case where the SMA actuator 30 is simply wound around the outer peripheral edge portions of the connecting pieces 21e, 21f; 22e, 22f.

  FIG. 14 is a block diagram showing the control means 60 of the lens driving module 1 configured as described above. The control means 60 includes a voltage supply circuit 61, a displacement sensor 62, and a lens drive control unit 63.

  The voltage supply circuit 61 is a driver of the SMA actuator 30, and applies a predetermined driving voltage to the SMA actuator 30 to heat it and generate a driving force. The voltage supply circuit 61 and the caulking metal fittings 31a and 32a serving as electrodes of the SMA actuator 30 are electrically connected by lead wires, and the drive voltage generated by the voltage supply circuit 61 is transmitted via the lead wires to the SMA actuator. 30.

  The displacement sensor 62 includes an optical position detection sensor such as a light reflection sensor or a photo interrupter, a magnetic position detection sensor using a Hall element, and the like, and detects position information of the lens unit 10. It is. The position information detected by the displacement sensor 62 is output to the lens drive control unit 63. The displacement sensor 62 is disposed at an appropriate position near the lens unit 10.

  The lens drive control unit 63 is composed of a microcomputer or the like, and controls the drive voltage supplied from the voltage supply circuit 61 to the SMA actuator 30. That is, the lens drive control unit 63, for example, in accordance with the movement target value of the lens unit 10 obtained based on the position control signal for autofocus and optical zoom and the current position information detected by the displacement sensor 62. A control signal for driving the actuator 30 is generated. This control signal is supplied to the voltage supply circuit 61, and a drive voltage corresponding to the movement target value is generated by the voltage supply circuit 61. By providing such a control means 60, the lens unit 10 can be positioned on the optical axis AX.

  Next, an embodiment in which the lens driving module 1 according to the present embodiment is incorporated in an imaging apparatus will be described. FIG. 15 is an external configuration diagram of a camera-equipped mobile phone 70 as an example of an imaging apparatus. Here, a case where the lens driving module 1 is incorporated in order to give an autofocus function and an optical zoom function to the lens unit 10 which is a component part of the camera unit OP built in the camera-equipped mobile phone 70 is illustrated. ing. In addition to the camera-equipped cellular phone 70, the lens driving module 1 according to the present embodiment is capable of imaging an imaging lens unit built-in digital still camera, digital video camera, or personal digital assistant (PDA). The present invention can also be suitably applied to an apparatus.

  FIG. 15A is a perspective view showing the front (operation surface) of the camera-equipped mobile phone 70, and FIG. 15B is a perspective view showing the back. The camera-equipped cellular phone 70 has a foldable structure in which a first casing 71 and a second casing 72 are connected by a hinge 73 as shown in FIG. An LCD (Liquid Crystal Display) 74 as a display unit for various information is provided on the front surface of the first housing 71, and a key input unit 75 is provided on the front surface of the second housing 71. . Further, as shown in FIG. 15B, the camera unit OP including the lens unit 10 is built in the back surface of the first housing 71 in a manner in which the objective lens is exposed.

  The key input unit 75 includes various dial buttons for operating a mobile phone function, a mode setting button for starting an image shooting mode and switching between still image and moving image shooting, and the lens unit 10 provided in the camera unit OP. A zoom button for controlling the optical zoom (magnification) operation, a shutter button for executing a photographing operation, and the like are included.

  FIG. 16 is a block diagram showing a schematic electrical configuration of the camera-equipped mobile phone 70. This camera-equipped mobile phone 70 includes a timing generator (TG) 81, an analog front end (AFE) 82, an image processing unit 83, an image memory, in addition to the lens driving module 1 and the image sensor 3 including the lens unit 10 described above. 84, an overall control unit 85, a shutter drive unit 86, a voltage supply circuit 87, a display unit 88, and an image recording unit 89.

  The lens unit 10 constitutes an imaging optical system that takes an optical image of a subject and guides it to the imaging device 3 disposed on the image side of the lens unit 10. The lens unit 10 includes a lens group 101 that forms an optical image of a subject and a shutter 102 that shields or transmits the optical path of the imaging optical system. A diaphragm 103 is disposed at an appropriate position of the lens group 101, and the lens group 101 includes a moving lens 104 for performing focus / zoom. An SMA actuator 30 for moving the moving lens 104 in the optical axis direction is attached to the lens unit 10.

  The timing generator 81 controls a photographing operation (charge accumulation based on exposure, reading of accumulated charge, and the like) by the image sensor 3. The timing generator 81 generates a predetermined timing pulse (vertical transfer pulse, horizontal transfer pulse, charge sweeping pulse, etc.) based on the reference clock output from the overall control unit 85 and outputs it to the image sensor 3. The imaging operation is controlled. Further, by generating a predetermined timing pulse and outputting it to the analog front end 82, the A / D conversion operation and the like are controlled.

  The analog front end 82 performs predetermined signal processing on the image signal (analog signal group received by each pixel of the CCD area sensor) output from the image sensor 3, converts the image signal into a digital signal, and outputs the digital signal to the image processing unit 83. To do. The analog front end 82 includes a correlated double sampling circuit for reducing reset noise included in the analog image signal voltage, an auto gain control circuit for correcting the level of the analog image signal, and a clamp circuit for fixing the potential indicating the black level. An A / D conversion circuit that converts analog R, G, and B image signals into, for example, a 14-bit digital signal is provided.

  The image processing unit 83 performs predetermined signal processing on the image data output from the analog front end 82 to create an image file. A black level correction circuit, a white balance control circuit, a color interpolation circuit, a gamma correction circuit, and the like It is configured with. The image data captured by the image processing unit 83 is temporarily written in the image memory 84 in synchronization with the reading from the image sensor 3, and thereafter the image data written in the image memory 84 is accessed to perform image processing. Processing is performed in each block of the unit 83.

  The image memory 84 temporarily stores the image data output from the image processing unit 83 in the shooting mode, and is used as a work area for performing predetermined processing by the overall control unit 85 on the image data. It is. In the playback mode, the image data read from the image recording unit 89 is temporarily stored.

  The overall control unit 85 includes a CPU (Central Processing Unit) and the like, and performs centralized control of each unit of the camera-equipped mobile phone 70 and also controls shooting operations. That is, the overall control unit 85 performs control of the timing generator 81, the voltage supply circuit 87 and the shutter drive unit 86 for the photographing operation, output control of the image signal, and the like.

  The overall control unit 85 is functionally provided with a focus control unit 851 and a zoom control unit 852. The focus control unit 851 generates a focus control signal for moving the moving lens 104 to the in-focus position based on predetermined distance measurement information. The zoom control unit 852 generates a zoom control signal for moving the moving lens 104 for optical zooming. These control signals are given to the voltage supply circuit 87. The shutter drive unit 86 opens and closes the shutter 102 so that the shutter 102 is opened for a predetermined time according to a shutter open / close control signal given from the overall control unit 85.

  The voltage supply circuit 87 corresponds to the voltage supply circuit 61 described with reference to FIG. 14, and generates a driving voltage for energizing and heating the SMA actuator 30 that drives the moving lens 104. That is, the voltage supply circuit 87 generates a drive voltage for driving the moving lens 104 by the SMA actuator 30 in accordance with the focus control signal and the zoom control signal.

  The display unit 88 corresponds to the LCD 74 shown in FIG. 15A, and can display a captured image, a live view image before imaging, and the like. The image recording unit 89 includes a memory card or the like, and stores image data that has been subjected to image processing by the image processing unit 83.

  According to the camera-equipped mobile phone 70 described above, since the lens driving module 1 described above is mounted, since the SMA actuator 30 is used, it is small and lightweight, has excellent impact resistance, has a small number of parts, and is inexpensive. Further, there are advantages that a lens movement amount necessary for autofocus and optical zoom can be secured and that high positional accuracy can be obtained without backlash. Further, a space for caulking the SMA actuator 30 around the lens unit 10 can be secured, the SMA actuator 30 can be used, and the arms 21a, 21b, 21c, 21d; 22a, 22b, 22c, It is possible to realize the camera-equipped mobile phone 70 that suppresses the warpage of 22d and makes it difficult for the suspension piece 15 of the lens unit 10 to drop off from the connection points 21g and 21h.

  Furthermore, when the SMA actuator 30 is wound around the connecting pieces 21e; 21f; 22e; 22f of the two thin plate-like link members 21, 22, the connecting pieces 21e; 21f; 22e; Therefore, it is possible to realize the camera-equipped mobile phone 70 that can suppress the buckling of the SMA actuator 30 and efficiently convert the driving force of the SMA actuator 30 into the moving force of the lens unit 10. In addition, the guide protrusion 16 and the guide groove 53c can suppress the impact and rotation of the lens unit 10 generated during assembly within the range of elastic deformation of the spring members 41 and 42, thereby improving the versatility of the lens. A camera-equipped mobile phone 70 can be realized.

[Embodiment 2]
FIG. 17 is an enlarged cross-sectional view showing the vicinity of a joint portion of two link members 21 ′ and 22 ′ in a lens driving module according to another embodiment of the present invention. This joint portion is similar to the joint portion shown in FIG. 4 described above, and corresponding portions are denoted by the same reference numerals and description thereof is omitted. It should be noted that in the present embodiment, the connecting pieces 21f and 22f of the two link members 21 'and 22' are both formed with recesses 21j and 22j 'in the same direction by the diaphragm, so that the intermediate base The recess 22j ′ of the link member 22 ′ on the 53 side is a boss 23 ′ that is a joining means. The SMA actuator 30 is wound around the boss 23 '.

  Accordingly, the head portion 23a ′ of the boss 23 ′ of the other link member 22 ′ is fitted into the recess 21j of the one link member 21 ′, and is thermally welded to the bottom surface 21k ′ using a laser, an ultrasonic wave, a heater, or the like. Thus, the link members 21 ′ and 22 ′ can be assembled. Accordingly, positioning and the like are easy and the assemblability is excellent, and the cost can be reduced without using a separate member for the boss 23 '.

  It should be noted that the boss 23 ′ is formed to have a smaller diameter as the distance from the bases 52 and 53 increases. With this configuration, the SMA actuator 30 is contracted and the pantograph is enlarged, so that both ends of the SMA actuator 30 are stretched at fixed positions by the columns 31 and 32, and the connecting piece 22f of the link member 22 ' The boss 23 'is formed to have a large diameter on the bases 52 and 53 side and a small diameter as the distance from the bases 52 and 53 increases. Together with the protrusion 22x, the SMA actuator 30 can be reliably prevented from sliding down to the bases 52 and 53 (the connecting piece 22f side), and interference between the SMA actuator and the connecting piece 22f can be prevented. Can do.

  As described above, the embodiment of the lens driving module according to the present invention has been described. However, the present invention is not limited to this, and for example, the SMA actuator 30 is wound around multiple times, or is divided into two at the midpoint support column 33 as a boundary. It is also possible to adopt other modes such as stacking a plurality of sets of the link members 21 and 22 and the like.

It is a perspective view which shows the main structural members of the imaging device containing the lens drive module which is a lens drive mechanism which concerns on one Embodiment of this invention. It is a disassembled perspective view of the imaging device shown in FIG. It is a longitudinal cross-sectional view of the imaging device shown in FIG. It is sectional drawing which expands and shows the junction part vicinity of the link member which concerns on one Embodiment of this invention. It is a top view of an intermediate base. It is a top view of an upper base. It is a perspective view in the state where the urging | biasing force by a bias spring is not applied to the spring member. FIG. 8 is a plan view of FIG. 7. It is a top view for demonstrating operation | movement of a link member and an SMA actuator. FIG. 10 is a side view of FIG. 9. It is a top view which shows typically the relationship between the contraction displacement of a SMA actuator, and the displacement of a link member. It is a side view which shows typically the relationship between the contraction displacement of a SMA actuator, and the displacement of a link member. It is a figure which shows typically the relationship between the input displacement and output displacement in the said FIG. It is a block diagram which shows the control means of a lens drive module. It is an external appearance block diagram of the mobile phone with a camera as an example of an imaging device. It is a block diagram which shows the rough electrical structure of the said mobile phone with a camera. It is sectional drawing which expands and shows the junction part vicinity of the link member which concerns on the other form of implementation of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lens drive module 2 Image pick-up device 3 Image pick-up element 10 Lens unit 11 Shooting lens 12 Lens frame 13 Lens tube 15 Suspension piece 15a Protrusion 16 Guide convex strips 21, 22; 21 ', 22' Link members 21a, 21b, 21c, 21d; 22a, 22b, 22c, 22d Arms 21e, 21f; 22e, 22f Connection pieces 21g, 21h; 22g, 22h Connection points 21i, 22i Notches 21j, 22j ', 22j Recess 21k Hole 22k Bottom surface 23 Pin 23' Boss 30 SMA Actuators 31-33 Posts 31a, 32a Caulking fittings 41, 42 Spring member 41b First annular portion 41c Second annular portion 41e Connecting piece 41g Suspension piece 43 Bias spring 51 Upper base 52 Lower base 53 Intermediate base 53b Hole 53c Guide groove 60 Control means 61 Voltage supply circuit 62 Displacement sensor 63 Lens Drive control unit 70 Camera-equipped mobile phone

Claims (4)

In a lens driving mechanism configured to include a lens unit and a driving unit that moves the lens unit in the optical axis direction by applying a driving force from the outer side of the lens unit.
The driving means includes
Two link members in which four arms are connected in a diamond shape so as to accommodate the lens unit therein;
Joining means for joining the corners in the major axis direction of the two link members to each other;
A linear shape memory alloy actuator wound between corners in the major axis direction of the link member;
The corner portion in the major axis direction of the two link members serves as an input end of the driving force, and the corner portion in the minor axis direction serves as the output end of the driving force, and the linear shape memory alloy actuator is contracted / relaxed. The corners in the minor axis direction are separated / proximately displaced from each other, and the lens unit suspended between the corners in the minor axis direction of one link member moves in the optical axis direction. A lens driving mechanism.   2. The lens driving mechanism according to claim 1, wherein the link member is formed in a plate shape, and the corner portion in the minor axis direction is formed narrower than the surroundings. The portion where the width is formed narrower than the surroundings in the corner portion of the minor axis direction is formed by a cut or slit formed in the minor axis direction,
At least one of the suspension piece of the lens unit mounted on the corner portion in the minor axis direction in the one link member and the contact portion of the base on which the corner portion in the minor axis direction contacts the other link member The lens driving mechanism according to claim 2, wherein a protrusion that fits into the slit or the slit is formed. The lens driving mechanism according to any one of claims 1 to 3,
An image sensor disposed on the image plane side of the lens unit;
An imaging apparatus comprising: control means for controlling the operation of the lens driving mechanism.

Images