JP2013120375A - Driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving device using a shape memory alloy SMA, which can be stably operated even immediately after the change of a body to be driven from a still state to a moving state.SOLUTION: A driving device 100 includes: a fixing member 4 having a through hole 4a; a body 1 to be driven which is driven so as to move back and forth in a direction along an axial line of the through hole 4a; an extension mechanism member 2 for driving the body 1 to be driven; an SMA actuator 3 which generates a driving force to move the extension mechanism member 2; and a guide mechanism 10 which is capable of moving the body 1 to be driven in an axial direction of a shaft member 13 provided along the axial line. Further, the driving device 100 includes an elastic member 5 which applies a side pressure SP to the shaft member 13 toward the center of the fixing member (in a direction AR) in a direction vertical to a direction along the axial line.

Description

  The present invention relates to a driving device that drives a small mechanical element using a shape memory alloy actuator, and particularly, a driving device suitable for moving a lens unit (driven body) constituting an imaging optical system in an optical axis direction. About.

  In recent years, there has been a dramatic increase in image quality, such as an increase in the number of pixels in an image sensor mounted on a camera-equipped mobile phone, etc. In addition to this, in addition to the basic function of image shooting, a focus function and zoom function Etc. are required.

  In order to add these functions, a lens driving device that moves the lens in the optical axis direction is necessary. Recently, a lens driving device using a shape memory alloy (SMA) actuator has been applied. Various studies have been made. This device generates contraction force by energizing and heating the SMA, and uses the contraction force as a lens driving force. It is easy to reduce the size and weight and obtain a relatively large driving force. There is an advantage that can be.

  As a lens driving device to which the SMA actuator is applied, for example, in the configuration of the driving device disclosed in Patent Document 1, driving is performed when the shape memory alloy wire 101 is contracted to obtain a driving force as shown in FIG. The tension urging direction AF is inclined by a predetermined angle θ from the optical axis, and is driven while exerting a pressing force that presses the inner wall of the sleeve 102 included in the lens unit 104 against the slide guide shaft 103. In other words, the slide guide shaft 103 is pressed against the sleeve 102 using the horizontal direction AH component of the tension AF generated when the shape memory alloy wire 101 suspended with the inclination θ contracts.

  In the configuration of the driving device disclosed in Patent Document 2, as shown in FIG. 9, a driving fulcrum portion 202 a of a lever member 202 that swings by the operation of the SMA wire 209 is provided at one corner of the fixing portion 201. A guide spring 204 is projected from the main body of the driven body 203 at the second corner opposite to the one corner, and the guide spring 204 is slidably supported and biased to bias the guide body 204. A drive guide unit 206 including 205 is provided, and the drive guide unit 206 includes upper and lower guide sleeves 208 a and 208 b that slidably hold the guide shaft 207.

JP 2009-122605 A International Publication No. 2011/065296

  However, in the configuration of the driving device disclosed in Patent Documents 1 and 2, the driving source of the moving mechanism with friction has the following problems. That is, when the driven body is changed from the stationary state to the moving state, the movement load is reduced from static friction to dynamic friction, and the linear SMA is loosened at the moment of starting movement, so that the shaft generating friction The drag itself decreases and the moving load decreases rapidly. As a result, the operation of the driven body immediately after changing from the stationary state to the moving state becomes very unstable. Further, in general, a drive device using SMA has a problem that such an unstable behavior occurs in each step because the drive device moves to a predetermined position in steps.

  The present invention has been made in view of the above circumstances, and provides a drive device using an SMA that can operate stably even after the driven body has changed from a stationary state to a moving state. For the purpose.

  In order to solve the above problems, the invention of claim 1 is directed to a driven body that is reciprocally driven in a predetermined direction, a mechanism member that drives the driven body, and a driving force that moves the mechanism member. A shape memory alloy actuator that generates the guide member, and a guide mechanism unit that can move the driven body along the axial direction of the shaft member, the moving direction of the driven body with respect to the shaft member The drive device further includes an elastic member that applies a lateral pressure in a vertical direction.

  The invention according to claim 2 is the drive device according to claim 1, further comprising a fixing member, the fixing member having a driving fulcrum portion with the mechanism member at one corner, and the mechanism member being A displacement input portion provided at the corner portion and engaged with the shape memory alloy actuator, and a contact portion provided so as to be displaceable by contact with the driven body at a predetermined facing position in plan view. And a displacement output unit for connecting the displacement input unit to the displacement input unit.

  The invention according to claim 3 is the drive device according to claim 2, wherein the driven body has a main body portion and a guide body portion protruding from the main body portion, and the shaft member is The guide body is integrally formed, the contact portion of the mechanism member contacts the guide body and drives the driven body, and the guide mechanism includes the guide body and the shaft member, It further includes first and second bearing portions provided on the upper and lower sides of the fixing member with respect to the guide body portion so as to be slidable and formed on the fixing member. .

  The invention according to claim 4 is the drive device according to claim 3, wherein both ends of the elastic member are fixed at predetermined positions of the fixing member, and a central portion thereof is the guide body portion. The side pressure is applied between the shaft member and the first and second bearing portions via the guide body due to the elasticity of the spring member.

  The invention according to claim 5 is the drive device according to claim 4, wherein the spring member includes a tension spring.

  Moreover, invention of Claim 6 is a drive device of Claim 4, Comprising: The said spring member contains a wire spring.

  The invention according to claim 7 is the drive device according to claim 4, wherein the spring member includes a torsion spring.

  The invention according to claim 8 is the drive device according to any one of claims 1 to 7, wherein the driven body is a lens unit, and a direction in which the driven body is driven is an optical axis direction. The shape memory alloy actuator is a shape memory alloy wire.

  According to the drive device of the first to fourth aspects of the present invention, an elastic member that applies a lateral pressure to the shaft member in a direction perpendicular to the moving direction of the driven body is provided. Since the present invention has the above characteristics, a constant lateral pressure is always applied to the shaft member, so that the force applied to the shaft member can be stabilized in a constant direction throughout. As a result, stable operation is possible even immediately after the driven body changes from the stationary state to the moving state. Moreover, the drive performance by the mechanism member with respect to the driven body along the axial direction of the shaft member can be stabilized, and the position control accuracy can be improved.

  According to the invention of claim 3, by providing the first and second bearing portions provided above and below the fixing member, a stable force is applied to the shaft member on the first and second bearing portions by the lateral pressure. It is possible to drive along the moving direction of the driven body while abutting with. That is, even if the first and second moments are generated in the first and second bearing portions, respectively, due to the force with which the expansion mechanism member abuts the guide body portion, the minimum lateral pressure that contacts the bearing portions is applied. Accordingly, when the driven member moves in the moving direction, the shaft member does not shake, and the driven member can be moved stably. For this reason, a more stable operation is possible immediately after the driven body changes from the stationary state to the moving state. Further, the driving performance can be further stabilized, and the position control accuracy can be further improved.

  According to the invention of claim 4, by fixing both ends of the spring member at a predetermined position of the fixing member, and by laying the central portion of the spring member on the side surface of the guide body portion, the elasticity of the spring member is achieved. Since a lateral pressure can be applied between the shaft member and the first and second bearing portions via the guide body portion, more stable operation can be performed immediately after the driven body changes from the stationary state to the moving state. It becomes possible. Further, the driving performance can be further stabilized, and the position control accuracy can be further improved.

  According to the invention of claim 5, it is possible to obtain a drive device having the same effects as those of the inventions of claims 1 to 4 by using a tension spring.

  According to the invention of claim 6, it is possible to obtain a drive device having the same effects as those of the inventions of claims 1 to 4 using a wire spring.

  According to the seventh aspect of the present invention, it is possible to obtain a drive device having the same effects as the first to fourth aspects of the present invention using the torsion spring.

  According to the invention of claim 8, the driven unit is a lens unit, the direction in which the driven unit is driven is the optical axis direction, and the shape memory alloy actuator is a shape memory alloy wire. It can be driven with high accuracy along the optical axis.

It is the schematic plan view which showed the component of the drive device which concerns on embodiment of this invention. It is the schematic sectional drawing which showed the component of the drive device which concerns on embodiment of this invention. It is a figure which illustrates typically the force which acts on the drive device concerning the embodiment of the present invention. It is a figure which illustrates typically the force which acts on the drive device concerning the embodiment of the present invention. It is a figure which shows the example of 1 structure of the elastic member of the drive device which concerns on embodiment of this invention. It is a figure which shows the example of 1 structure of the elastic member of the drive device which concerns on embodiment of this invention. It is a figure which shows the example of 1 structure of the elastic member of the drive device which concerns on embodiment of this invention. It is the schematic sectional drawing which showed the component of the conventional drive device. It is the schematic sectional drawing which showed the component of the conventional drive device. It is a figure explaining operation | movement of the to-be-driven body in the conventional drive device.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, parts having the same configuration and function are denoted by the same reference numerals, and redundant description is omitted in the following description. Further, the drawings are schematically shown, and the sizes, positional relationships, and the like of various structures in the drawings are not accurately illustrated.

<1. Overview and overall configuration of drive unit>
<1-1. Basic configuration>
FIG. 1 and FIG. 2 are diagrams schematically showing components of a driving apparatus 100 configured using a driving mechanism that drives a driven body using an SMA actuator according to an embodiment of the present invention. . Among these, FIG. 1 shows a plan view of the driving device 100 viewed from the driven body 1 side, and FIG. 2 is a cross-sectional view of the driving device 100 taken along the line I-I in FIG.

  As shown in FIGS. 1 and 2, the driving apparatus 100 according to the present embodiment moves the driven body 1 (for example, a lens unit including an imaging lens) in the axis line (for example, the optical axis) AX direction. The fixing member 4 having the through-hole portion 4a, the driven body 1 supported so as to be reciprocally movable in the direction of the axis AX in the through-hole portion 4a, and the drive for moving the driven body 1 The structure includes a shape memory alloy actuator (SMA actuator) 3 that applies force, and an expansion mechanism member 2 that receives a driving force from the SMA actuator 3 and moves the driven body 1. In addition, the driving device 100 includes a bias spring 7 that biases the driven body 1 in a direction against a driving force caused by contraction of the SMA actuator 3.

  The driven body 1 includes a main body portion 14 that can store the imaging lens unit LU in a fixed state, and a guide body portion 12 that protrudes from the main body portion 14.

  The fixing member 4 is fixed to a member (for example, an image pickup device substrate of a mobile phone) in which the driving mechanism is employed, and is, for example, an immovable member that constitutes the bottom side of the driving device. Etc. In the present embodiment, the shape of the fixing member 4 is a quadrangular shape in plan view, and has the corners of the first corner C1, the second corner C2, the third triangle C3, and the fourth corner C4. (See FIG. 1).

  Therefore, the driving fulcrum portion 4b of the magnifying mechanism member 2 is provided at the first corner portion C1, and the guide mechanism portion 10 including the bias spring 7 is provided at the second corner portion C2 that is located diagonally to the first corner portion C1. It is configured. Further, as a support portion for holding the shape memory alloy actuator 3 so as to be energized, an energization support portion 30A is provided in the third triangular portion C3, and an energization support portion 30B is provided in the fourth square portion C4.

  The guide mechanism portion 10 disposed at the second corner portion C2 slidably supports the shaft member 13 formed integrally with the guide body portion 12 protruding from the main body portion 14 of the driven body 1. At the same time, the biased body 7 has a function of biasing the driven body 1 in a direction against the driving force exerted by the enlargement mechanism member 2. Therefore, other members are not buffered by the circular main body portion 14 of the driven body 1 that is displaceably mounted in the through hole portion 4a of the fixing member 4.

  The magnifying mechanism member 2 includes a displacement input portion 2a provided at the first corner C1 and engaged with the SMA actuator 3, and a contact portion provided so as to be displaceable by contacting the driven body 1 with the second corner C2. 22b, the corresponding contact portion 22b, and the displacement input portion 2a are connected to each other and have a displacement output portion 2b composed of a ring shape portion 21b in a ring shape in plan view, and cut along line II in FIG. The cross section is L-shaped when viewed from the side (see FIG. 2). The magnifying mechanism member 2 is configured such that the displacement amount of the displacement output portion 2b in the axis AX direction is larger than the displacement amount of the displacement input portion 2a due to the input of the moving force F1. In other words, the driven body 1 is moved in the direction of the axis AX with an amount of displacement larger than the input of the moving force F1 to the displacement input portion 2a by the output from the contact portion 22b.

  The SMA actuator 3 gives a moving force F1 to the expansion mechanism member 2, and is a linear actuator made of a shape memory alloy (SMA) wire (linear body) such as a Ni-Ti alloy. The SMA actuator 3 expands when given a predetermined tension in a state where the elastic modulus is low (martensite phase) at a low temperature. When heat is applied in this extended state, the SMA actuator 3 undergoes phase transformation and has 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 3 is employ | adopted. That is, since the SMA actuator 3 is a conductor having a predetermined resistance value, Joule heat is generated by energizing the SMA actuator 3 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, the first electrode 30 </ b> A and the second electrode 30 </ b> B for energization heating are fixed to both ends of the SMA actuator 3. These electrodes 30 </ b> A and 30 </ b> B are fixed to a predetermined electrode fixing portion (not shown) provided on the fixing member 4.

  As shown in FIG. 1, the SMA actuator 3 is stretched over the extended portion 23 of the magnifying mechanism member 2 so as to be folded back in a “<” shape. With this configuration, when the SMA actuator 3 is energized and heated via the electrodes 30A and 30B and is actuated (shrinks), a moving force F1 is applied to the lever member 2, and the expanding mechanism member 2 swings due to the moving force F1. Will be.

  The bias spring 7 increases the size of the components housed in the driven body 1 having a circular shape in plan view and makes it possible to move the driven body 1 stably. Instead, it is provided at a position for biasing the guide body 12 protruding from the main body 14. As described above, the drive device 100 according to the present embodiment is configured to include the guide mechanism unit 10 that attaches the bias spring 7 to a position that protrudes away from the main body 14 of the driven body 1 that is circular in plan view. Yes. As the bias spring 7, for example, a compression coil spring that can be easily attached to the outer peripheral portion of the shaft member 13 and can easily obtain a predetermined biasing force can be suitably used.

  A guide body 11, which is a member constituting the guide mechanism section 10, includes a guide body section 12 and a shaft member 13 that are part of the driven body 1. The shaft member 13 extends in the optical axis direction, which is the axis AX, and the first and second bearing portions 4c1 provided at the upper end portion and the lower end portion of the fixing member 4 with respect to the guide body portion 12, respectively. , 4c2 is slidably supported. A bias spring 7 is attached between the upper surface of the guide body 12 and the fixing member 4 so as to surround the shaft member 13, and the bias spring 7 is fitted to the shaft member 13. Since the guide body 12 and the shaft member 13 are integrated, the shaft member 13 moves simultaneously with the movement of the driven body 1. As described above, since the guide body 12 and the shaft member 13 are integrated, it is possible to integrally form the same material.

  As described above, the basic configuration of the driving device 100 according to the present embodiment includes the fixed member 4 having the through hole portion 4a and the driven body 1 that is driven to reciprocate in the direction along the axis AX of the through hole. And a magnifying mechanism member 2 for driving the driven body 1 and a shape memory alloy actuator 3 for generating a driving force for moving the magnifying mechanism member 2. And the fixing member 4 has a driving fulcrum part 4a with the magnifying mechanism member 2 at one corner (first corner C1), and the driven body 1 and the first corner C1 in plan view with the main body 14. And a guide barrel portion 12 formed by projecting from the main body portion 14 at a predetermined facing position (second corner portion C2) facing each other across the axis AX, and a shaft member 13 integrated with the guide barrel portion 12 have. The first and second bearing portions 4c1 and 4c2 in the guide mechanism portion 10 slidably support the guide body 11 by moving the shaft member 13 up and down, and the enlargement mechanism member 2 exhibits the guide body 11. It further has a bias spring 7 that biases in a direction against the driving force. The magnifying mechanism member 2 can be displaced by contacting the driven body 1 with the displacement input portion 2a provided in the first corner portion C1 and engaged with the shape memory alloy actuator 3 in plan view. And a displacement output portion 2b composed of a ring form portion 21b that connects the contact portion 22b, the corresponding contact portion 22b, and the displacement input portion 2a to form a ring shape in plan view.

<1-2. General Properties and Preconditions for Driving a Drive Device Using SMA>
In preparation for explaining the details of the driving device 100 in this embodiment, the general characteristics of driving of the driving device using the SMA, which is the premise of this embodiment, and the accompanying phenomenon, that is, the situation that occurred in the prior art I will explain.

  8 and 9 are schematic cross-sectional views showing the components of the conventional driving device as described above, and FIG. 10 is a diagram for explaining the operation of the driven body in the conventional driving device. FIG. 10A is a diagram for explaining the drag (vertical axis) generated in the bearing portion with respect to the SMA energization amount (horizontal axis), and FIG. It is a figure explaining the displacement (vertical axis) of a driver.

  In general, in a drive device using SMA, when energization is started in a stationary SMA (corresponding to shape memory alloy wire 101 in FIG. 8 and SMA wire 209 in FIG. 9), the temperature of the SMA increases. Along with this, the driving force of the SMA also increases. Here, since the driven body is accompanied by friction, the resistance against the SMA (corresponding to the resistance Na in FIG. 8 and the resistance Nb in FIG. 9) is the bearing portion (in FIG. 8, the sleeve 102, in FIG. 9, the guide sleeve 208a, 208), and a static frictional force is generated by this drag force. Therefore, as shown in FIG. 10A, the driven body does not start moving until the driving force of the SMA exceeds the “static friction force + bias force” (a state before reaching the point P1 from the point P0). ). Thereafter, the energization of the SMA is increased, and the driven body starts moving at the moment when the generated force exceeds “static friction force + bias force” (a state where the driven body has reached the point P1).

  However, the linear SMA that does not have rigidity enough to maintain the self-form causes loosening at the moment when the driven body starts moving. For this reason, if the driving device does not use SMA, the static frictional force changes to dynamic frictional force and stabilizes. However, in the driving device using SMA, the drag itself generated in the bearing portion due to the loosening of SMA is short. It greatly decreases with time (a state in which it decreases from the point P1 to the point P2). That is, the drag generated in the bearing portion decreases from N1 to N2 and stabilizes unless the drive device uses SMA, whereas the drag decreases from N1 to N3 in a short time in the drive device using SMA. Then, the operation is stabilized at N2 as the SMA tension increases due to further energization (increase from point P2 to point P3). That is, the difference Ra between the drag N1 and the drag N2 shown in FIG. 10A is an area corresponding to the difference between the static friction force and the dynamic friction force, and the difference Rb between the drag N2 and the drag N3 is It becomes a region of drag due to loosening of SMA.

  Next, the operation of the driven body will be described with reference to FIG. When energization is started in a stationary SMA, the temperature of the SMA rises as the amount of energization increases, and the driving force of the SMA also rises, but the driven body moves until the driving force of the SMA exceeds “static friction force + bias force” Is not started (state before reaching point Q1 from point Q0). Thereafter, the energization of the SMA is increased, and the driven body starts moving at the moment when the driving force of the SMA exceeds the “static friction force + bias force” (a state where the driving body has reached the point Q1). At that time, in addition to the reduction of the static friction force to the dynamic friction force, the drag that generated the friction is reduced in a short time as described above, so that a large acceleration is obtained (increase from the point Q1 to the point Q2). State to do). The driven body that has started to move with a large acceleration continues to move (from point Q2) while reducing its energy by dynamic friction and a bias spring (corresponding to the spring member 105 in FIG. 8 and bias spring 205 in FIG. 9). The state is increased to the point Q3), and the movement is synchronized and stabilized at a position (a state where the point Q3 has been reached) that balances with the SMA having increased the energization amount and the tension.

  The driven body that has started to move with a large acceleration may have a loose SMA at that time, and there is no means for braking. Therefore, the section Pa until the driven body consumes energy due to dynamic friction and bias force and can be stably moved by the SMA with increased energization and tension is an uncontrollable area.

  SMAs are often incorporated into small precision devices due to their small size and simplicity. Especially for devices that require position control on the order of μm, such as camera focus, it is a big problem that movement at the start of movement is not stable. . In actual camera focus driving, the lens is usually operated in small stepped steps, which is a fatal problem if the initial operation at each step is unstable.

  Under such a background, the present invention realizes a driving device that can stably operate even after the driven body is changed from the stationary state to the moving state in the driving device using the SMA.

  In addition to the above basic configuration, a specific configuration that is a characteristic part of the embodiment will be described below.

<2. Specific Configuration of Embodiment>
Returning to the description of the embodiment of the present invention. In the drive device 100 according to the present embodiment, the contact portion 22b of the enlargement mechanism member 2 is engaged with the driven body 1, and the enlargement mechanism member 2 rotated by the SMA actuator 3 pushes up the driven body 1. However, the position of the pushing-up contact portion 22b is separated from the guide mechanism portion 10 by a predetermined distance. For this reason, when the driven body 1 is pushed up by the magnifying mechanism member 2, it receives a moment force around the guide mechanism portion 10.

  Therefore, the drive device 100 according to the present embodiment employs a configuration in which the shaft member 13 is pressed against the first and second bearing portions 4c1 and 4c2 using this moment force. That is, the driving device 100 includes the elastic member 5 in order to apply the lateral pressure SP in a direction perpendicular to the direction along the axis AX and in the central direction of the fixing member 4 (see FIG. 1). That is, as shown in FIG. 1, both ends of the elastic member 5 are fixed to predetermined positions (fixed ends 35 </ b> A and 35 </ b> B) of the fixed member 4, and the central portion is installed on the side surface of the guide body 12. Side pressure SP is applied between the shaft member 13 and the first and second bearing portions 4c1 and 4c2 through the guide body portion 12 by expansion and contraction of the spring member. Will be.

  Here, with reference to FIG. 10 again, driving of the driving apparatus 100 according to the present embodiment will be described. As in the prior art, when the SMA actuator 3 is gradually energized and heated from the stationary state of the driven body 1, a driving force is generated in the SMA actuator 3 (from point P0 to point P1 in FIG. 10A). A state before starting, a state before reaching point Q1 from point Q0 in FIG. 10B). The driven body 1 starts moving when the driving force by the SMA actuator 3 exceeds the “static friction force + bias force” generated at the two first and second bearing portions 4c1 and 4c2 (FIG. 10 (a) at a point P1 and FIG. 10 (b) at a point Q1). At this time, as described above, a phenomenon occurs in which the SMA actuator 3 is loosened. When there is no side pressure SP, the rotational moment applied to the driven body 1 is abruptly reduced due to the looseness of the SMA actuator 3 as in the prior art, and thus occurs in the first and second bearing portions 4c1 and 4c2. Since the drag force, that is, the frictional force that has been reduced rapidly (the state where the drag force decreases from the point P1 to the point P2 in FIG. 10A), the driven body 1 becomes unstable (FIG. 10). (B) State from the point Q1 to the point Q3 via the point Q2).

  However, in the driving device 100, since the side pressure SP is provided, the shaft member 13 is pressed against the first and second bearing portions 4c1 and 4c2 when the SMA actuator 3 is loosened, so that a reduction in drag is minimized. It becomes possible. As a result, the unstable movement of the driven body in the section Pa, which has conventionally occurred in FIG. 10B, is suppressed to a minimum, and the uncontrollable area becomes small. That is, in the driving apparatus 100, it is possible to realize an ideal movement of the driven body 1 as indicated by a broken line L1 in FIG.

  As described above, in the driving apparatus 100 using the linear SMA actuator 3 that does not have rigidity enough to maintain the self-form, the SMA actuator 3 is immediately after the start of driving by applying the lateral pressure SP. The uncontrollable area (section Pa in FIG. 10B) due to loosening is greatly improved. Thus, more stable operation is possible immediately after the driven body changes from the stationary state to the moving state.

<2-1. Relationship between the position of the contact portion of the expansion mechanism member and the moment>
The relationship between the position of the contact portion 22b of the magnifying mechanism member 2 and the above-described moment will be described with reference to FIGS. 3 and 4 are diagrams schematically illustrating the force acting on the driving device 100. In FIG. 3, the contact portion 22b of the enlargement mechanism member 2 is in contact with the guide mechanism portion 10 apart from the contact mechanism. On the other hand, in FIG. 4, the contact portion 22 b of the expansion mechanism member 2 is in contact with the guide body portion 12 and is infinitely close to the guide mechanism portion 10.

  When driving the driven body 1 in the direction of the axis AX, the shaft member 13 is pressed against the first and second bearing portions 4c1 and 4c2 in the same direction, and the shaft member 13 is moved to the first and second bearings. It is desirable that the reciprocating drive is performed while maintaining the state in contact with the portions 4c1 and 4c2.

  However, at the position of the contact portion 22b shown in FIG. 3, the first moment generated in the first bearing portion 4c1 with respect to the driving force F that pushes up the driven body 1 in which the magnifying mechanism member 2 houses the lens. M1a and the second moment M2a generated in the second bearing portion 4c2 are generated in opposite directions, and a moment MW (not shown) generated in the second bearing portion 4c2 is generated by the weight W of the lens. In particular, since the influence of the first and second moments M1a and M2a generated in the first and second bearing portions 4c1 and 4c2 is larger than the moment MW, the influence of the moment MW can be ignored. For this reason, it is difficult to maintain the state in which the shaft member 13 is pressed in the same direction against the first and second bearing portions 4c1 and 4c2, and as a result, the shaft member 13 is likely to run out. become.

  On the other hand, at the position of the contact portion 22b shown in FIG. 4, the contact portion 22b of the magnifying mechanism member 2 is in contact with the guide body portion 12, and is provided at a position as close as possible to the guide mechanism portion 10. . Here, the moment refers to the outer product of the position vector and the momentum vector. When the distance from the contact portion 22b to the shaft member 13 corresponding to the position vector increases, the first bearing portion 4c1 generates the first. Moment M1 (M1a, M1b) and the second moment M2 (M2a, M2b) generated in the second bearing portion 4c2. That is, based on this principle, the first and second moments M1a and M2a in the configuration of FIG. 3 are much larger than the first and second moments M1b and M2b in the configuration of FIG. 4 (M1a> M1b). , M2a> M2b). Therefore, in order to prevent shaft runout of the shaft member 13, the configuration of FIG. 3 has a greater lateral pressure SP (at least SP>) than the configuration of FIG. 4 with respect to the first and second bearing portions 4c1 and 4c2. Since M1a) is required, it is necessary to apply a relatively large lateral pressure SP to the guide body 12.

  As described above, when the driven body 1 is driven, the side pressure SP needs to have a force that does not float just before the shaft member 13 starts to float from the first and second bearing portions 4c1 and 4c2. In the configuration shown in FIG. 3, it is necessary to satisfy at least the relationship of “side pressure SP> first moment M1a”.

  Therefore, in the drive device 100 according to the present embodiment, as shown in FIG. 4, the contact portion 22 b of the magnifying mechanism member 2 contacts the guide body portion 12, and the like from the contact portion 22 b to the guide mechanism portion 10. It is desirable to make the distance as small as possible. As a result, the applied side pressure SP can be made relatively small (if SP> M1b is satisfied). For this reason, when moving in the direction of the axis AX, the shaft member 13 is likely to run out due to the effects of the first and second moments generated in the first and second bearing portions 4c1 and 4c2, respectively. On the other hand, it can be effectively suppressed.

  According to the driving apparatus 100 according to the present embodiment as described above, the lateral pressure SP is applied to the shaft member 13 in a direction perpendicular to the direction along the axis AX and in the central direction of the fixing member 4 (direction AR in FIG. 1). By providing the elastic member 5 that gives a constant pressure, a constant side pressure SP is always applied to the shaft member 13, so that a minimum side pressure SP that contacts the first and second bearing portions 4c1 and 4c2 is applied. Thus, the force applied to the shaft member 13 can be stabilized in a fixed direction (direction in which the shaft member 13 is brought into contact with the first and second bearing portions 4c1 and 4c2). As a result, the driving performance of the magnifying mechanism member 2 with respect to the driven body 1 along the axial direction of the shaft member 13 can be stabilized, and an improvement in position control accuracy is realized. Hereinafter, this point will be described in detail.

  By providing the first and second bearing portions 4c1 and 4c2 provided above and below the fixed member 4, the shaft member 13 is applied to the first and second bearing portions 4c1 and 4c2 with a stable force by the side pressure SP. It is possible to drive the driven body 1 along the axis AX direction while making contact. That is, the first and second moments M1 (M1a, M1b) and M2 (M2a, M2) are applied to the first and second bearing portions 4c1 and 4c2, respectively, with respect to the portion where the expansion mechanism member 2 contacts the guide body portion 12. Even when M2b) occurs, by moving to the axis AX direction by setting the minimum side pressure SP (SP> M1a, SP> M2a) in contact with the first and second bearing portions 4c1, 4c2, The shaft member 13 does not swing, and the driven body 1 can be moved stably. For this reason, the driving performance can be further stabilized, and the position control accuracy can be further improved.

  Note that the direction of the side pressure SP does not have to be exactly exactly the same as the direction AR (see FIG. 1) that is accurately directed to the axis AX (center point), and the direction AR is included in the direction of the side pressure SP. If it is enough. That is, the direction of the side pressure SP includes not only the direction AR accurately but also a direction toward the direction AR (that is, a direction slightly deviated from the direction AR).

  Furthermore, with respect to the driving apparatus 100 according to the present embodiment, when the driven body 1 is a lens unit, the direction in which the driven body is driven (axis AX direction) is an optical axis direction, and the SMA actuator 3 is an SMA wire. The lens unit can be accurately driven along the optical axis.

<3. Configuration example of elastic member>
Hereinafter, a specific configuration example of the elastic member 5 described above will be described with reference to FIGS.

<3-1. Configuration Example of First Elastic Member>
FIG. 5 is a diagram illustrating an example in which a tension spring 5 </ b> A is used as a spring member constituting the elastic member 5 described above. The spring member shown in FIG. 1 also shows the tension spring 5A, and FIG. 5 is a schematic diagram showing the drive device 100 of FIG. 1 in a simplified manner.

  Both ends of the tension spring 5A are fixed to the fixed ends 35A and 35B of the fixing member 4, and the contraction force 5A1 and 5A2 of the tension spring 5A is provided by laying the center portion of the tension spring 5A on the side surface of the guide body portion 12. Since the side pressure SP can be applied between the shaft member 13 and the first and second bearing portions 4c1 and 4c2 via the guide body portion 12, the driving performance can be further stabilized and the position control accuracy can be improved. Can be further improved.

<3-2. Configuration Example of Second Elastic Member>
FIG. 6 is a diagram for explaining an example in which a wire spring 5B is used as a spring member constituting the elastic member 5 described above. FIG. 6 is a schematic diagram showing the driving device 100 of FIG. 1 in a simplified manner.

  Both ends of the wire spring 5B are fixed to the fixed ends 35A and 35B of the fixing member 4, and the central portion of the wire spring 5B is installed on the side surface of the guide body portion 12 so that the contraction forces 5B1 and 5B2 of the wire spring 5B are obtained. Since the side pressure SP can be applied between the shaft member 13 and the first and second bearing portions 4c1 and 4c2 via the guide body portion 12, the driving performance can be further stabilized and the position control accuracy can be improved. Can be further improved.

  In FIG. 6, the wire spring 5 </ b> B has a curved shape in order to avoid interference with the driven body 1.

<3-3. Configuration Example of Third Elastic Member>
FIG. 7 is a diagram for explaining an example in which a torsion spring 5C is used as the spring member constituting the elastic member 5 described above. FIG. 7 is a schematic diagram showing the driving device 100 of FIG. 1 in a simplified manner.

  Both ends of the torsion spring 5C are fixed to the fixing ends 35A and 35B of the fixing member 4, and the central portion of the torsion spring 5C is installed on the side surface of the guide body 12 to thereby cause the contraction forces 5C1 and 5C2 of the torsion spring 5C. Since the side pressure SP can be applied between the shaft member 13 and the first and second bearing portions 4c1 and 4c2 via the guide body portion 12, the driving performance can be further stabilized and the position control accuracy can be improved. Can be further improved.

  In FIG. 7, the torsion spring 5 </ b> C has a curved shape in order to avoid interference with the driven body 1. In addition, when the torsion spring 5C is employed in the driven body 100, it should be noted that, for example, a position where the spring is twisted is secured by deepening the moat of the concave portion 1A of the driven body 1 shown in FIG.

<4. Modification>
As mentioned above, although embodiment of this invention has been described, this invention is not limited to the said embodiment, A various deformation | transformation is possible.

  * In the driving device 100 according to the present embodiment, the driven body 1 and the enlargement mechanism member 2 are formed in a circular shape along the outer peripheral portion of the through-hole portion 4a. The body 1 and the expansion mechanism member 2 may be provided.

  * In the driving apparatus 100 according to the present embodiment, the shape of the fixing member 4 in plan view is a quadrangle, but it may be circular or polygonal, and the installation position of the driving fulcrum part 4b and the displacement input part 2a provided on the fixing member 4 ( Any structure may be used as long as the guide mechanism unit 10 including the bias spring 7 is provided at a position (second position) opposed to the corner AX across the axis AX.

  * In the driving device 100 according to the present embodiment, the guide body 11 corresponding to a part of the driven body 1 and the shaft member 13 are integrated in the guide body 11 of the guide mechanism section 10. The guide body 12 and the shaft member 13 may be separated from each other. Specifically, the shaft member 13 is configured to be integrated with the first and second bearing portions 4c1 and 4c2, and the guide body portion 12 integrated with the driven body 1 slides on the shaft member 13. Moving. In addition, the guide trunk | drum 12 is pressed by the shaft member 13 with the elastic member 5 similarly to the drive device 100 which concerns on the said embodiment. In the configuration in which the driven body (lens unit 104) is directly moved by the shape memory alloy wire 101 as shown in FIG. 8, the guide body (sleeve 102) integrated with the driven body is moved by the elastic member 5. The shaft member (slide guide shaft 103) may be pressed.

DESCRIPTION OF SYMBOLS 1 Driven body 2 Magnification mechanism member 2a Displacement input part 2b Displacement output part 3 Shape memory alloy wire (SMA actuator)
4 fixing member 4a penetrating portion 4b driving fulcrum portion 4c1 first bearing portion 4c2 second bearing portion 7 bias spring 10 guide mechanism portion 11 guide body 12 guide body portion 13 shaft member 14 body portion 21b ring form portion 22b abutting portion 100 Drive device AX Optical axis (axis)
F Driving force M1 First moment M2 Second moment SP Side pressure

Claims (8)

A driven body driven to reciprocate in a predetermined direction;
A mechanism member for driving the driven body;
A shape memory alloy actuator that generates a driving force for moving the mechanism member;
A guide mechanism capable of moving the driven body along the axial direction of the shaft member;
With
An elastic member that applies a lateral pressure to the shaft member in a direction perpendicular to the moving direction of the driven body;
Further comprising:
Drive device. The drive device according to claim 1,
A fixing member, the fixing member has a driving fulcrum portion with the mechanism member at one corner,
The mechanism member is provided at the corner portion and a displacement input portion with which the shape memory alloy actuator is engaged is abutted so as to be displaceable by abutting the driven body at a predetermined opposed position in plan view. A displacement output unit that connects the portion, the corresponding contact portion, and the displacement input unit,
Drive device. The drive device according to claim 2,
The driven body has a main body part and a guide body part protruding from the main body part,
The shaft member is integrally formed with the guide body;
The contact portion of the mechanism member contacts the guide body portion to drive the driven body;
The guide mechanism portion includes the guide body portion and the shaft member, and is formed on the fixing member.
The shaft member further includes first and second bearing portions provided above and below the fixed member so as to be slidably held,
Drive device. The drive device according to claim 3,
The elastic member includes a spring member whose both ends are fixed at predetermined positions of the fixing member, and a central portion of which is installed on a side surface of the guide body portion, and the guide body portion is formed by elasticity of the spring member. The lateral pressure is applied between the shaft member and the first and second bearing portions via
Drive device. The drive device according to claim 4,
The spring member includes a tension spring,
Drive device. The drive device according to claim 4,
The spring member includes a wire spring,
Drive device. The drive device according to claim 4,
The spring member includes a torsion spring,
Drive device. The drive device according to any one of claims 1 to 7,
The driven body is a lens unit;
The direction in which the driven body is driven is the optical axis direction,
The shape memory alloy actuator is a shape memory alloy wire,
Drive device.

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