JP2009122603A - Driving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a driving device which can stably straight-move a compact driven body such as a lens and uses a shape memory alloy hardly causing oscillation by suppressing resonance with a simple configuration without adding components. <P>SOLUTION: In the driving device equipped with the driven body 3, an elastic support member elastically supporting the body 3, and the string-like shape memory alloy 5 displacing the body 3, a middle part of the string-like shape memory alloy is bridged over a predetermined suspension part, and both ends thereof are fixed at fixed terminal parts, and also response speed when heating and when cooling is made different between the first area 51 of the string-like shape memory alloy from the bridging part 50 to one fixed terminal part and a second area 52 from another fixed terminal part to the bridging part. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a drive device that drives a small mechanical element, and in particular, a drive device using a shape memory alloy suitable for suppressing resonance of a driven body and moving a lens of an optical device in an optical axis direction. About.

  Conventionally known examples of lens driving means used in a photographing apparatus such as a camera include a combination of a rotary motor, a speed reduction mechanism, a direction changing mechanism, and the like, and a linear motor. Further, in a micro lens unit represented by a recent portable camera or the like, the mechanism using the rotary motor and the speed reduction mechanism described above has many elements and a large size. Furthermore, in a drive mechanism using a rear motor using an ultrasonic motor or the like, the size of the optical axis in the projected area direction can be reduced, but a predetermined size is required in the optical axis direction and cannot be reduced.

  Further, since these drive devices have a low output energy density, and the size of the device decreases, the output decreases accordingly. Therefore, there has been a clear limit to downsizing the lens drive device.

  For this reason, development of an actuator using a shape memory alloy, which is known to be small but have a high energy density, has been underway. Moreover, the linear drive device using the length variation of several% (for example, 3 to 5%) of the total length using the string-like shape memory alloy can be configured. Furthermore, the linear drive device which expanded the amount of displacement can be comprised by combining this string-like shape memory alloy and a variable magnification mechanism.

  If a shape memory alloy having a large energy density is used, a small and high output drive mechanism can be configured. As the drive mechanism, there are conventionally known two types of systems, a so-called “bias spring system” that balances with a separately provided bias spring and a “push-pull system” that actively balances with an equivalent shape memory alloy. ing.

  In any of the above methods, the position is determined by the balance of elastic force, and each has a unique natural frequency. Even if the drive system has a natural frequency, it is not a problem if the moving speed is low and the stop position is two points. However, when position control is performed at a high speed, or when there are a plurality of stop positions such as intermediate stops, there may be a serious problem.

  For this reason, in a drive device using a shape memory alloy, in order to achieve high-speed response, the balance between the material characteristics of the shape memory alloy and the force of the bias spring is taken into account, and the temperature hysteresis of the actuator is reduced to reduce camera shake. A drive device and a drive control method for preventing the above have already been disclosed (for example, see Patent Document 1).

  When energized between both ends of the string-shaped shape memory alloy, it is heated by the generated Joule heat and contracts to the memory length when it reaches a predetermined temperature (heating contraction process). On the other hand, when the energization is cut off from this high temperature state, it is cooled to a predetermined temperature or less by heat radiation, released from the shape memory state, and extended by an elastic force such as a separately provided bias spring (cooling extension process).

  In general, the string-like shape memory alloy has a so-called hysteresis in which the temperature at which the same length appears is different in the heating shrinkage process and the cooling elongation process. Also, the transformation temperature rises and falls as the load increases and decreases. These characteristics are factors that deteriorate the responsiveness of the shape memory alloy. For this reason, it is preferable to reduce the friction of the drive system as much as possible in order to form a responsive drive mechanism, and it is possible to configure a linear drive device combined with a guide mechanism that allows the lens to move straight with low friction. It has been demanded.

As a guide mechanism that enables linear movement with low friction, a parallel link mechanism including a pair of opposed parallel leaf springs is known. Therefore, an actuator device (driving device) that moves a lens or the like using a parallel leaf spring mechanism and a shape memory alloy has already been disclosed (for example, see Patent Document 2).
JP 2003-125590 A JP 2002-130114 A

  In a method of holding a driven body using a parallel link mechanism including a pair of parallel leaf springs, the driven body can be moved straightly in a low friction state. However, in a low friction state, it is difficult to suppress a resonance phenomenon caused by a spring force such as a parallel leaf spring or a bias spring.

  Further, in order to stably move the driven body in parallel, it is effective to hold the parallel leaf spring in a both-sided state instead of being cantilevered. For this purpose, if the driven body is a lens barrel having a circular lens, a disk donut-shaped parallel leaf spring is mounted around the lens barrel. However, in this way, the configuration in which the disk donut-shaped parallel leaf springs are mounted on both surfaces of the lens barrel that moves in parallel, for example, both the upper and lower surfaces, not only increases the load, but also the mounting work of parts and the like from either surface However, it is difficult to assemble a shape memory alloy or a zooming mechanism disposed around the lens barrel.

  In addition, as described in Patent Document 1, in the configuration in which the drive control unit that controls the operation of the movable unit including the shape memory alloy is provided in order to reduce the temperature hysteresis of the actuator, the device configuration becomes complicated and the number of parts is reduced. It is not easy because it increases the size and costs.

  Therefore, the present invention provides a driving device using a shape memory alloy that is capable of stably moving a small driven body such as a lens or the like in a straight line, suppressing resonance with a simple configuration without adding parts, and hardly oscillating. The purpose is to do.

  In order to achieve the above object, the present invention provides a driving device including a driven body, an elastic support member that elastically supports the driven body, and a string-shaped shape memory alloy that displaces the driven body. The intermediate part of the shape memory alloy is hung on a predetermined suspension part, both ends thereof are fixed to the fixed terminal part, and the first region of the string-like shape memory alloy from the crossing part to one fixed terminal part and The second region from the other fixed terminal portion to the bridge portion is characterized in that the response speed during heating and cooling is different.

  With the above configuration, when the elastically supported driven body is driven via the string-shaped memory alloy, the response speed of the left and right first and second areas of the string-shaped memory alloy to be passed Therefore, slipping and friction are generated in the spanning portion, which acts as a frictional force that suppresses vibration generated in the moving direction of the driven body. Therefore, it is possible to obtain a drive device that can effectively suppress the occurrence of resonance that occurs when the driven body is driven by expanding and contracting the string-shaped shape memory alloy.

  Further, in the drive device having the above-described configuration, the response speed can be varied by adopting a configuration in which the length of the string-like shape memory alloy is different between the first region and the second region. it can.

  Alternatively, the response speed can also be varied by adopting a configuration in which a heat radiating member is attached to one of the string-shaped memory alloys of the first region and the second region.

  Further, the present invention provides a driving device including a driven body, an elastic support member that elastically supports the driven body, and a string-shaped shape memory alloy that displaces the driven body, and uses a plurality of string-shaped shape memory alloys. The driven body is displaced and the response speed at the time of heating and cooling of at least one of the plurality of string-like shape memory alloys is different from other string-like shape memory alloys. It is characterized by being composed.

  With the above configuration, when driving the elastically supported driven body via the plurality of string-shaped memory alloys, at least one of the plurality of string-shaped memory alloys to be mounted is heated and cooled Since the response speed is made different, it is not a simple vibration system, but a complex vibration system that exhibits multiple spring constants is configured, and when the driven body is driven by expanding and contracting the string-like shape memory alloy It is possible to obtain a drive device that can effectively suppress the occurrence of resonance.

  Further, the present invention may be configured such that, in the drive device having the above-described configuration, the length of at least one string-shaped shape memory alloy among the plurality of string-shaped shape memory alloys is made different. It is good also as a structure which attaches a heat radiating member to at least 1 string-like shape memory alloy among alloys.

  According to the present invention, when the driven body is driven via the string-like shape memory alloy, the response speeds in the first and right first and second areas of the string-like memory alloy hanging part to be hung on the suspension part. Therefore, slipping and friction are generated in the spanning part, acting as a frictional force that suppresses vibrations that are likely to occur in the direction of movement of the driven body, and with a simple configuration that does not add parts, A drive device that suppresses resonance that occurs in the moving direction can be obtained. In addition, when the driven body is made via a plurality of string-like shape memory alloys, the response speed at the time of heating and cooling of at least one string-like shape memory alloy is different from other string-like shape memory alloys. Therefore, a complex vibration system that exhibits multiple spring constants is configured to exhibit the anti-resonance function, and the driven body has a simple configuration that does not add special parts for vibration prevention. Thus, it is possible to obtain a drive device that easily suppresses resonance that occurs in the moving direction.

  Embodiments of the present invention will be described below with reference to the drawings. 1A and 1B show a first embodiment of a drive device according to the present invention, in which FIG. 1A is a plan view and FIG. 1B is a side view. FIG. 2 shows a second embodiment of the drive device according to the present invention, where (a) is a plan view and (b) is a side view. 3A and 3B are schematic views showing a third embodiment of the drive device according to the present invention, wherein FIG. 3A is a partial cross-sectional view, and FIG. 3B is a side view thereof. 4A and 4B are schematic views showing a fourth embodiment of the drive device according to the present invention, wherein FIG. 4A is a partial cross-sectional view, and FIG. 4B is a side view thereof. Moreover, the same code | symbol is used about the same structural member, and detailed description is abbreviate | omitted suitably.

  First, the drive device 1A of the first embodiment will be described with reference to FIG. The drive device 1A according to the first embodiment includes an elastic support member that elastically supports the driven body 3 and a string-shaped shape memory alloy 5 that displaces the driven body 3, and a string shape that exhibits a driving force. An intermediate portion of the shape memory alloy is mounted so as to be hung on a predetermined suspension portion (a suspension portion provided on the driven body or a suspension portion provided separately), and one of the string-like shape memory alloys is attached from the hanging portion. The first region to the end of the second region and the second region from the other end to the spanning portion are configured to exhibit a resonance prevention function by varying the response speed at the time of heating and cooling. Is.

  Therefore, as shown in FIG. 1 (b), when the magnification changing mechanism 6 for enlarging the amount of expansion / contraction displacement of the string-like shape memory alloy 5 is used, the driving device 1A is attached to the base 2 and the base 2. A driven body 3 that is movably supported via an elastic support member is provided, and a string-like shape memory alloy 5 that displaces the driven body 3 is hung on a suspension portion 63 provided in a zoom mechanism.

  The elastic support member for elastically supporting the driven body 3 includes a method of sandwiching the front and rear end faces in the moving direction of the driven body 3 by a pair of parallel leaf springs 4 fixed to the base 2, and a predetermined direction. There is a method of using a bias spring 7 that biases the spring. Alternatively, the parallel plate spring 4 and the bias spring 7 may be provided together.

  Therefore, in the example using the parallel leaf spring 4 shown in practice in the figure, the front and rear end faces in the moving direction of the driven body 3 are sandwiched between the first leaf spring 4A and the second leaf spring 4B, and the base 2 The end portion is fixed to the fixed terminal portion 22A provided on the base member and the string-like shape memory alloy 5 stretched over the suspension portion 63 of the magnification changing mechanism 6 is contracted to displace the driven body 3 upward in the figure. be able to.

  Next, the parallel leaf spring 4 and the zoom mechanism 6 will be described. The parallel leaf spring 4 is composed of a first leaf spring 4A having a double-sided configuration located on the lower surface in the drawing and a second leaf spring 4B having a cantilever configuration located on the upper surface in the drawing. 4 A of 1st leaf springs have the 1st adhering part 41 and 2nd adhering part which become an adhering part with a base part in the both ends, and become an adhering part with the to-be-driven body 3 in the center part in a figure. A third fixing portion 43 is provided. The second leaf spring 4 </ b> B has a first fixing portion 41 that becomes a fixing portion with the base 2 at the end portion and a third fixing portion 43 that becomes a fixing portion with the driven body 3 at the center portion.

  In some cases, a scaling mechanism is used to obtain a predetermined amount of displacement of the driven body by enlarging the amount of displacement of the string-shaped shape memory alloy 5 that is displaced by only a few percent of the total length. For example, the zooming mechanism 6 shown in the present embodiment is composed of a lever member that is pivotably mounted on a support portion 21 provided on the base 2 via a shaft support portion 60, from the shaft support portion 60 and the shaft support portion 60. A driving arm 61 having two arms extending in two directions with a predetermined angle apart from each other and a suspension arm 62 suspended from the shaft support 60 in a direction perpendicular to the driving arm 61 are provided. Further, projecting portions 31 that engage with the drive arm 61 are provided on both outer sides of the axis of the driven body 3.

  A suspension portion 63 for suspending the string-like shape memory alloy 5 is formed on the distal end side of the suspension arm 62 provided to hang from the shaft support portion 60. The drive arm 61 can be turned around the shaft support 60 by the string-like shape memory alloy 5 being wound around the suspension 63 and contracted. At this time, the distance L1 from the shaft support portion 60 to the suspension portion 63 is set to a length shorter than the distance L2 from the shaft support portion 60 to the contact portion of the protruding portion 31, and an arm configuration for obtaining a predetermined zooming amount is obtained. Thus, the so-called lever principle is used to increase the expansion / contraction displacement amount of the string-like shape memory alloy 5, so that the arm length ratio between the distance L1 and the distance L2 is changed to obtain a desired scaling factor. be able to.

  At this time, it is preferable that the support portion 21 is provided on the second fixing portion 42 side of the base on which the second leaf spring 4B is not mounted. If it is this structure, it will become possible to assemble | attach string-shaped shape memory alloy 5 and another component with respect to this support part 21 easily from the working space opened to the upper part in a figure. In addition, since the string-shaped shape memory alloy 5 is suspended on the suspension arm 62 that hangs down from the shaft support 60, the protrusions 31 and 31 that are spaced apart from the shaft support 60 by a predetermined angle and are substantially equidistant are pushed up. The driving force due to the contraction of the string-shaped shape memory alloy 5 can be evenly transmitted through the two driving arms 61, and the driven body 3 can be moved in a straight line stably.

  For example, as shown in FIG. 1A, the base 2 has a rectangular cross-sectional shape, and a circular through-hole portion through which the driven body 3 can be inserted is formed at the center of the base 2. ing. Moreover, the 1st adhering part 41 is provided in the corner of this rectangle, and the 2nd leaf | plate spring 4B is mounted | worn. The support portion 21 is provided at the opposite corner facing the second leaf spring 4B, and the string-like shape memory alloy 5 and the zoom mechanism 6 are mounted. Further, fixed terminal portions 22 of the string-like shape memory alloy 5 are provided in the remaining two corners.

  As shown in the figure, the second leaf spring 4B is a leaf spring having a shape with arms along two sides of the rectangle, but is mounted on the opposite surface of the driven body 3 so as to face this. The first leaf spring 4A has a polygonal arm portion along the four sides of the rectangle, and has a single leaf spring configuration in which the arm portion of the second leaf spring 4B is annularly arranged.

  The string-shaped shape memory alloy 5 is fixed so that both ends thereof are fixed to fixed terminal portions 22A and 22B provided at two diagonal corners, and the suspension portion 63 is wound so that the outside of the driven body 3 is sandwiched. Attached in a letter or U shape. This winding part will be referred to as a spanning part 50.

  In this configuration, the anti-resonance function is achieved by deliberately varying the response speed at the time of heating and cooling of the string-shaped shape memory alloy 5 in the left and right regions of the spanning portion to form vibration systems having different spring constants. It became clear that it demonstrated. Therefore, in the present embodiment, as shown in FIG. 1 (a), the first region from the spanning portion 50 to one end portion of the string-like shape memory alloy, and the other end portion to the hooking portion. The length of the string-like shape memory alloy 5 is made different in the second region up to the transfer portion.

  As shown in the figure, the string-like memory alloy 5 that exerts a driving force is fixed to the fixed terminal portions 22A and 22B of the base 2, and can be swung via a shaft support portion 60 attached to the support portion 21. It is configured to be hung on the suspension part 63 of the zoom mechanism 6. Further, by setting the angle folded from the spanning portion 50 to the terminal portions 22A and 22B as a predetermined angle, the fixed terminal portions 22A and 22B are energized and heated, the string-like shape memory alloy 5 is contracted, The drive arm 61 of the zoom mechanism 6 can be turned to drive the driven body 3 in a displacement manner.

  At this time, the length W1 of the first region 51 from the fixed terminal portion 22A, which is one end portion, to the span portion 50, and the second region, from the fixed terminal portion 22B, which is the other end portion, to the span portion 50. The length W2 of 52 is a different length.

  In the string-like shape memory alloy 5 having different left and right lengths from the spanning portion, the left and right string-like shape memory alloys are not displaced until a predetermined reaction temperature after being energized, and the temperature rises. When the reaction temperature is reached, it shrinks at the same shrinkage rate. However, in the first region having a long length, the contracting length becomes long, and in the second region having a short length, the shrinking length becomes short. For this reason, a phenomenon occurs in which the length of contraction in the same time is different, and the apparent response speed is different.

  If the response speeds of the first region 51 and the second region 52 on the left and right sides of the span 50 are different, a difference in stress is generated and transmitted as a frictional force to the span 63 suspended. Since this frictional force is in a direction perpendicular to the moving direction of the driven body 3, that is, in the lateral direction, a frictional force is generated in the lateral guide member and the like. By this frictional force, energy loss is generated in a vibration system including the string-shaped shape memory alloy 5, the parallel leaf spring 4, the bias spring 7, and the like, and the function of suppressing resonance by exerting a function to prevent vibration is exhibited.

  That is, by making the vibration system more complicated and generating a frictional force that effectively prevents vibration, resonance that is likely to occur in a simple vibration system can be suppressed.

  In order to exhibit the function of suppressing this resonance, it is important to set the ratio of the lengths of the first region 51 and the second region 52 within a predetermined range. Moreover, in order to displace the to-be-driven body 3 smoothly, it is not preferable that those lengths differ greatly. Therefore, in the present embodiment, the length of the second region 52 is 5 to 30% shorter than the length of the first region 51.

  As described above, it occurs when the driven shape 3 is driven by expanding and contracting the string-shaped memory alloy 5 by changing the left and right lengths of the spanning portion of the string-shaped memory alloy 5 by 5 to 30%. A drive device 1A that can effectively suppress the occurrence of resonance can be obtained.

  Moreover, the response speed at the time of heating and cooling of the left and right regions can also be intentionally different by adopting a configuration in which the heat dissipation conditions of the left and right regions of the spanning part are made different. This embodiment will be described with reference to FIG.

  The drive device 1B of the second embodiment shown in FIG. 2 is similar to the drive device 1A described above, in that the base 2, the driven body 3, the pair of parallel leaf springs 4, the string-like shape memory alloy 5, and the zoom mechanism. 6. The same applies to the use of the bias spring 7. However, the difference is that the heat radiating member 8 is attached to one of the left and right regions of the spanning portion 50. At this time, the left and right lengths folded back from the spanning portion 50 of the string-shaped shape memory alloy 5 may be the same. It is also possible to use a combination of heat dissipation members mounted on the left and right with different lengths. In any case, it is only necessary that the response speeds at the time of heating and cooling of the left and right regions differ to such an extent that the vibration isolation effect is exhibited.

  In the present embodiment, the left and right lengths of the string-like shape memory alloy folded back from the spanning portion 50 are the same. For this purpose, as shown in FIG. 2A, the string-like shape memory alloy 5 of the driving device 1B is fixed to the fixed terminal portions 22 and 22 provided at positions spaced by an equal distance from the spanning portion 50 at a predetermined angle. Both ends are fixed. Further, the heat radiating member 8 is mounted in the vicinity of one fixed terminal portion 22.

  The string-like shape memory alloy 5 in the region where the heat dissipating member 8 is attached has a slower heating rate during heating and an increased cooling rate during cooling. Therefore, even if the length from the spanning part 50 to the fixed terminal part 22 is the same, the response speed is different, and the apparent spring constant is different. Thus, similarly, the vibration system can be made more complicated, and resonance that is likely to occur in a simple vibration system can be suppressed.

  As the heat radiating member 8, for example, heat radiating grease, heat radiating gel, or the like can be used. By attaching the heat radiating member 8 to a predetermined position, heat dissipation can be imparted to the string-shaped shape memory alloy 5. It is clear that the degree of change in response speed during heating and cooling can be adjusted by adjusting the amount of adhesion.

  As described above, in the case of a drive device using a single string-like shape memory alloy 5, the intermediate portion is mounted so as to be hung on a suspension portion provided on the driven body 3 or a suspension portion provided separately. The response speed at the time of heating and cooling differs between the first region from the spanning portion to one end of the string-shaped shape memory alloy and the second region from the other end to the spanning portion. It becomes a structure and it becomes possible to exhibit a resonance prevention function.

  Next, a third embodiment and a fourth embodiment of the drive device according to the present invention will be described with reference to FIGS.

  FIG. 3 shows a drive device 1 </ b> C of the third embodiment that includes a driven body 3 </ b> A that includes the guide shaft 11 and slides along the slide shaft 10. Further, as shown in FIG. 3A, a suspension member 13 is provided that hangs the string-shaped shape memory alloy 5 on the end of the slide block 12 included in the driven body 3A. Then, the string-like shape memory alloy 5 contracts and is urged in the direction of the arrow D1 in the drawing to drive the driven body 3A. At this time, a bias spring 7A for biasing in the direction opposite to the direction in which the string-shaped memory alloy 5 contracts (direction of arrow D2 in the figure) is attached.

  At this time, as shown in FIG. 3 (b), the length of the string-shaped shape memory alloy 5 to be hung so as to wind the suspension member 13 is varied by changing the length from the hanger to the fixed terminal. It is configured to demonstrate the prevention function.

  That is, the length W1 of the first region 51A from the fixed terminal portion 22A to the suspension portion of the suspension member 13 is longer than the length W2 of the second region 52A from the fixed terminal portion 22B to the suspension portion of the suspension member 13. Then, by being configured such that the response speed at the time of heating and that at the time of cooling are different, as described above, a frictional force in the lateral direction of the guide shaft 11 is generated and the resonance preventing function is exhibited.

  Since the guide shaft 11 is mounted to prevent lateral rotation in a direction perpendicular to the direction of movement of the driven body 3, the string-shaped shape memory alloy 5 and the bias spring 7A are caused to move by the generated frictional force. An energy loss is generated in the vibration system provided, and the function of suppressing vibrations is exhibited by acting to prevent vibration.

  As described above, the ratio of the different lengths is preferably about 5 to 30%. In the present embodiment, the length of the second region 52A is 5 to 30% shorter than the length of the first region 51A. I am trying.

  In the third embodiment 1C, the suspension member is provided on the movable driven body and the fixed terminal portion is provided on the fixed side. On the contrary, on the movable side, It is also possible to provide a configuration in which a fixed terminal portion is provided on the driven body and a suspension member is provided on the fixed side. This example will be described with reference to FIG.

  The drive device 1D of the fourth embodiment shown in FIG. 4A includes a guide shaft 11 and slides along the slide shaft 10 in the same manner as the drive device 1C of the third embodiment shown in FIG. 3A to be driven. The same is true in that the string-shaped shape memory alloy 5 is stretched over the suspension member to provide the first region and the second region having different lengths. However, the difference is that the fixed terminal portions 22A and 22B are provided at a predetermined distance apart on the movable slide block 12A, and the spanning portion 13 of the string-like shape memory alloy 5 is provided on the fixed portion 14 side.

  Even in this configuration, as shown in FIG. 4B, the length W1 of the first region 51B from the fixed terminal portion 22A to the spanning portion of the suspension member 13 is set to be equal to the length of the suspension member 13 from the fixed terminal portion 22B. The length can be made longer than the length W2 of the second region 52B to the spanning portion, and the response speed at the time of heating and cooling can be made different so that the resonance preventing function can be exhibited.

  For example, according to the frequency analysis result of the vibration waveform shown in FIG. 6, the gain (vibration magnitude) G1 of the resonance part before the vibration prevention measures is obtained after the vibration prevention measures (in the first region and the second region). In an example in which the length is changed and the response speed at the time of heating is different from that at the time of cooling, it can be seen that the gain is reduced to G2. Thus, according to the present embodiment, it is possible to obtain a drive device that suppresses resonance that occurs in the direction of movement of the driven body with a simple configuration in which no components are added.

  As described above, an intermediate portion of the string-shaped shape memory alloy is stretched over a predetermined suspension portion, both ends thereof are fixed to the fixed terminal portion, and the string-shaped shape memory from the spanning portion to one fixed terminal portion. The first region of the alloy and the second region from the other fixed terminal portion to the spanning portion are configured to have different response speeds at the time of heating and cooling, so that the spanning portion can slip. Friction occurs and acts as a frictional force that suppresses vibrations generated in the direction of movement of the driven body, thereby exhibiting a resonance prevention function.

  Further, in the case of a drive device configured using a plurality of string-like shape memory alloys, the response speed at the time of heating and cooling of at least one string-like shape memory alloy of the plurality of string-like shape memory alloys, The anti-resonance function can also be exhibited by being configured differently from other string-like shape memory alloys.

  For example, the example shown in FIG. 5 is an example in which a plurality of, for example, three string-like shape memory alloys 5A, 5B, and 5C are installed in a straight line between the fixed portion 14A and the movable portion 12B (fifth embodiment). ).

  In this example, both ends of the string-like shape memory alloy 5A are fixed to the fixed terminal portions 22C and 22C, both ends of the string-like shape memory alloy 5B are fixed to the fixed terminal portions 22D and 22D, and both ends of the string-like shape memory alloy 5C. Is fixed to the fixed terminal portions 22E and 22E. Moreover, it can energize from these fixed terminal parts, respectively, can shrink each string-like shape memory alloy 5A, 5B, 5C simultaneously, and can displace a movable part.

  In this case, at least one of the length WA of the string-like shape memory alloy 5A, the length WB of the string-like shape memory alloy 5B, and the length WC of the string-like shape memory alloy 5C. The length of the string-like shape memory alloy is made different. In this way, at least one string-like shape memory alloy of the plurality of string-like shape memory alloys is made different by changing the length of at least one string-like shape memory alloy among the plurality of string-like shape memory alloys. By making the response speed at the time of heating and cooling different from those of other string-like shape memory alloys, a complex vibration system that exhibits a plurality of spring constants can be configured to exhibit a resonance preventing function.

  Further, the lengths of the plurality of string-like shape memory alloys may all be different. Further, it is also possible to adopt a configuration in which the above-described heat dissipation member is attached to at least one of the plurality of string-like shape memory alloys, or at least one of the plurality of string-like shape memory alloys. It is also possible to adopt a configuration that exhibits a resonance preventing function by making the response speed at the time of heating and cooling the string-shaped shape memory alloy different from those of other string-shaped shape memory alloys. Furthermore, it is possible to use both mounting of the heat dissipating member and different lengths.

  In any case, in a driving device including a driven body, an elastic support member that elastically supports the driven body, and a string-shaped shape memory alloy that displaces the driven body, a plurality of string-shaped shape memory alloys are used. Thus, when displacing the elastically supported driven body, the response speed at the time of heating and cooling of at least one of the plurality of string-like shape memory alloys depends on the other string-like shape memory. By being configured differently from the alloy, it is possible to configure a driving device that forms a complex vibration system and generates a frictional force that prevents vibration and effectively exhibits a resonance preventing function.

  The driving device 1A shown in FIG. 1 and the driving device 1B shown in FIG. 2 described above can be used for an imaging device having a small lens unit that linearly moves the lens in the optical axis direction. In that case, the driven body 3 is a lens barrel, and the axis is the optical axis. The base 2 supporting the lens barrel having a circular cross section is a rectangular parallelepiped unit having a rectangular cross section in a direction perpendicular to the optical axis, so that the four corners around the lens barrel are used as component mounting spaces. It becomes possible. Therefore, it becomes easy to provide a support portion 21 for pivotally supporting the magnification changing mechanism 6 and winding the string-shaped shape memory alloy 5 at one corner of the rectangle. Moreover, the fixed terminal portions 22 and 22 of the string-like shape memory alloy 5 can be provided in two places adjacent to the one corner. If it is this structure, it will become a drive device which can be mounted also on a small lens unit, and it will become easy to carry out the straight movement of the optical axis direction of a lens, and it will become a drive device of a lens which can be mounted also in a mobile phone etc. .

  The string-like shape memory alloy 5 is in a superelastic state when not energized, and is stretched by the restoring force of a pair of parallel leaf springs. At this time, it is also possible to provide a separate bias spring for extending the string-shaped shape memory alloy 5. When power is supplied from a power supply unit (not shown) from the fixed terminal portions at both ends, the cord-shaped memory alloy 5 is heated by Joule heat and contracts to the stored length. When the string-shaped shape memory alloy 5 contracts, an urging force acts in the direction of arrow E1 in FIG. 1B, and pushes up the drive arm 61 in the direction of arrow E2. That is, the lens barrel can be moved in the optical axis direction.

  At this time, as described above, the upper and lower portions of the lens barrel are sandwiched between a pair of parallel leaf springs, and one leaf spring is held in a supported state so as to be stably movable, and the middle of the string-like shape memory alloy. The response speed during heating and cooling differs between the first area from the suspension to one end and the second area from the suspension to the other end. Since the anti-resonance function is exhibited, the lens barrel can be stably moved straight without resonating in the optical axis direction.

  Moreover, it is preferable that the spring force of the 1st leaf | plate spring 4A and the 2nd leaf | plate spring 4B which comprise the parallel leaf | plate spring 4 is substantially equivalent to the spring force of the part which overlaps seeing from the optical axis direction. This means that the spring forces of the parts constituting the parallel leaf springs are made equal, and the positions of the fixed part with the base and the fixed part with the lens barrel (driven body) are aligned. In addition, the spring force of the portion that does not overlap when viewed from the optical axis direction, that is, the both-end support portion, is a spring force within a predetermined range required for the driven body or the lens barrel to be clamped to move straight without being tilted. Good.

  Therefore, the double-supported first leaf spring 4A can be composed of a single leaf spring or a plurality of, for example, two leaf springs. Also, a plurality of leaf spring configurations is preferable because each spring force can be easily changed to a desired value.

  With the above configuration, when the lens barrel is driven, it is possible to obtain a driving device that effectively suppresses resonance and has less vibration and enables the lens unit to move straight.

  As described above, according to the drive device according to the present invention, when the driven body is driven via the string-shaped shape memory alloy, the left and right first regions of the string-shaped memory alloy passed over the driven body and The response speed at the time of heating and cooling of at least one string-like shape memory alloy of the plurality of string-like shape memory alloys to be mounted is different from that of the other string-like shape memory alloys. Therefore, it is a simple structure that creates a complex vibration system and generates frictional force effective to prevent vibration, exhibits resonance prevention function, and does not add special parts for vibration prevention, It is possible to obtain a drive device that easily suppresses resonance that occurs in the moving direction of the driven body. Further, since the driven body can be stably moved straight through the string-shaped shape memory alloy, the driving apparatus is suitable for a photographing apparatus having a small lens unit that moves the lens body straight in the optical axis direction. Can be used.

These show 1st embodiment of the drive device which concerns on this invention, (a) is a top view, (b) is a side view. These show 2nd embodiment of the drive device which concerns on this invention, (a) is a top view, (b) is a side view. These are the schematic diagrams which show 3rd embodiment of the drive device which concerns on this invention, (a) shows a partial cross section figure, (b) shows the side view. These are the schematic diagrams which show 4th embodiment of the drive device which concerns on this invention, (a) shows a partial cross section figure, (b) shows the side view. These are side views which show 5th embodiment of the drive device which concerns on this invention. Is a frequency analysis result of the vibration waveform.

Explanation of symbols

1A, 1B, 1C, 1D, 1E Driving device 2 Base 3 Driven body 4 Parallel leaf spring 4A First leaf spring 4B Second leaf spring 5 String-shaped shape memory alloy 6 Scaling mechanism 22, 22A, 22B Fixed terminal portion 50 Hanging part 51 First area 52 Second area 63 Suspension part

Claims (6)

In a drive device comprising: a driven body; an elastic support member that elastically supports the driven body; and a string-shaped shape memory alloy that displaces the driven body.
The middle part of the string-like shape memory alloy is hung on a predetermined suspension part, both ends thereof are fixed to the fixed terminal part, and the string-like shape memory alloy from the hanging part to one fixed terminal part is A drive device characterized in that one region and a second region from the other fixed terminal portion to the transfer portion have different response speeds during heating and cooling.   2. The driving device according to claim 1, wherein the first region and the second region have different lengths of the string-like shape memory alloy.   3. The drive device according to claim 1, wherein a heat radiating member is attached to one of the string-shaped shape memory alloys of the first region and the second region. In a drive device comprising: a driven body; an elastic support member that elastically supports the driven body; and a string-shaped shape memory alloy that displaces the driven body.
The driven body is displaced using a plurality of string-like shape memory alloys, and the response speed at the time of heating and cooling of at least one string-like shape memory alloy of the plurality of string-like shape memory alloys A driving device configured to be different from the string-like shape memory alloy.   5. The drive device according to claim 4, wherein at least one of the string-like shape memory alloys has a different length.   6. The drive device according to claim 4, wherein a heat radiating member is attached to at least one of the string-like shape memory alloys.

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