JP2009050142A - Drive unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate assembling and reduce the number of components and the cost. <P>SOLUTION: In a drive unit (10), which is equipped with an electromechanical converting element (13), a vibrating member (14) attached to the end (13b) of this electromechanical converting element, and a shifting member (12) frictionally coupled with this vibrating member, and in which the shifting member can move in the direction of expansion and contraction of the electromechanical converting element, the vibrating member (14) has a flexible hook (142) which hooks the shifting member (12) by its elasticity. A spring (15) engages with the vibrating member (14) and the flexible hook (142), and generates pressing force for pressing the flexible hook (142) against the shifting member (12). The vibrating member (14) has a groove (14a) V-shaped in cross section at a frictional coupling part between the vibrating member and the shifting member (12). <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a drive device, and more particularly to a drive device using an electromechanical transducer such as a piezoelectric element.

  Conventionally, linear actuators using electromechanical transducers such as piezoelectric elements, electrostrictive elements, and magnetostrictive elements have been used as autofocus actuators and zoom actuators for cameras.

  For example, Patent Document 1 discloses a piezoelectric element, a drive shaft (a wear-resistant vibration rod or vibration member) that is coupled to the piezoelectric element and extends in the expansion / contraction direction of the piezoelectric element, and a target that is frictionally coupled to the drive shaft. A driving device including a driving member (a zoom lens barrel, a moving member) is disclosed. In Patent Document 1, a driven signal (zoom lens barrel, moving member) is driven by devising a drive signal to be applied to a piezoelectric element. In Patent Document 1, a drive shaft (vibrating member) is sandwiched between a driven member (moving member) and a friction plate. In other words, the drive shaft (vibrating member) penetrates between the driven member (moving member) and the friction plate. The friction plate is pressed by the pressure contact spring in a direction to sandwich the drive shaft (vibrating member) with the driven member (moving member).

  Further, Patent Document 2 provides a second piezoelectric element that secures or releases the frictional engagement between the driving member (vibrating member) attached to the first piezoelectric element and the driven member (moving member). An actuator that can stably and accurately move a driven member is disclosed. The actuator disclosed in Patent Document 2 includes a pair of first piezoelectric elements for driving, a second piezoelectric element for engagement, a pair of driving members, and a pressing spring. The pair of first piezoelectric elements and the pair of driving members are disposed on both sides of the driven plate. The distance between the pair of driving members is enlarged or reduced by the second piezoelectric element. By this second piezoelectric element, the frictional engagement between the pair of driving members and the driven plate is secured or released.

  Patent Document 3 discloses that the mover is made of a liquid crystal polymer containing carbon fiber, thereby reducing the cost and weight and reducing the moving speed and driving force compared to the case where the mover is made of a metal material. A high-performance drive device using a mover having a high flexural modulus is disclosed. The driving device disclosed in Patent Document 3 includes a piezoelectric element (electromechanical conversion element) that expands and contracts when a voltage is applied, a drive shaft (vibration member) that is fixed to one end of the piezoelectric element in the expansion and contraction direction, and a drive. A mover (moving member) that frictionally engages the shaft is provided, and a weight (stationary member, weight) fixed to the other end of the piezoelectric element in the expansion / contraction direction. The movable element (moving member) is moved along the driving shaft (vibrating member) by causing the driving shaft to vibrate by varying the expansion or contraction speed or acceleration of the piezoelectric element. The drive shaft is constituted by a shaft body of a round bar extending linearly. The mover includes a mover main body and a cap, and both engage with the drive shaft so as to sandwich the drive shaft. In order to allow the mover to move along the drive shaft, the mover body and the cap are pressed against the drive shaft by a substantially U-shaped leaf spring so that a predetermined frictional force is generated between the drive shaft and the mover. . The mover body is provided with a groove having a V-shaped cross section. A drive shaft is fitted into the groove so that two inclined surfaces of the groove come into contact with the drive shaft. Similarly, the cap is provided with a groove having a V-shaped cross section. When the cap is combined with the mover main body, the drive shaft is fitted in the groove of the cap, and the two inclined surfaces of the groove come into contact with the drive shaft.

  Furthermore, Patent Document 4 discloses a drive device that can stably drive a moving member at high speed. The drive device disclosed in Patent Document 4 is coupled to a stationary member, an electromechanical conversion element having one end in the expansion / contraction direction fixed to the stationary member, and the other end in the expansion / contraction direction of the electromechanical conversion element. A driving member (vibrating member) supported so as to be movable in the expansion / contraction direction of the mechanical conversion element, a moving member frictionally coupled to the driving member and supported so as to be movable in the expansion / contraction direction of the electromechanical conversion element, and driving Friction force applying means for generating a friction force between the member (vibrating member) and the moving member is provided. The frictional force adding means includes an elastic member that is fixed to the moving member and generates a pressing force, and a sandwiching member that transmits the pressing force generated by the elastic member to the driving member. Moreover, the contact part of a moving member and a drive member and the contact part of a pinching member are made into V-shaped cross section.

Japanese Patent No. 3188851 JP 2006-54979 A JP 2006-304529 A Japanese Patent No. 3141714

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

  In the drive device disclosed in Patent Document 1, a friction plate is required separately to frictionally couple the drive shaft (vibrating member) and the zoom lens barrel (driven member, moving member). Therefore, there is a problem that the assemblability is inferior, the number of parts increases, and the cost is increased.

  Since Patent Document 2 includes a plurality of piezoelectric elements, the configuration is complicated and it is disadvantageous to reduce the size.

  In Patent Document 3, a mover (moving member) is composed of a separate mover body and a cap, and both engage with a drive shaft (vibrating member) so as to sandwich the drive shaft (vibrating member). . Therefore, like the above-mentioned Patent Document 1, there is a problem that the assemblability is inferior, the number of parts is increased, and the cost is increased.

  In the driving device disclosed in Patent Document 4, the driving member (vibrating member) is sandwiched between the moving member and the sandwiching member (pad), and the sandwiching member (pad) is pushed against the driving member (vibrating member) by the elastic member (leaf spring). I guess. Therefore, like the drive device disclosed in Patent Document 1 or 3 described above, there is a problem that the assemblability is inferior, the number of parts is increased, and the cost is increased.

  The subject of this invention is providing the drive device which can aim at simplification of an assembly.

  The other subject of this invention is providing the drive device which can reduce a number of parts.

  Still another object of the present invention is to provide a drive device that can reduce the cost.

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

  According to the present invention, the electromechanical transducer element (13; 23) having a pair of ends opposed to each other in the expansion / contraction direction, and the vibration member (14) attached to one of the pair of ends of the electromechanical transducer element. 22) and a moving member (12; 24) frictionally coupled to the vibration member, and in the drive device (10; 10A; 20) in which the moving member can move in the expansion / contraction direction of the electromechanical transducer. One of the vibrating member and the moving member has a flexible sandwiching portion (142; 242) that sandwiches the other of the vibrating member and the moving member by elasticity, and the flexible sandwiching portion serves as the vibrating member. And a biasing member (15; 15A; 15) for biasing the other of the moving members and applying a frictional force between the vibrating member and the moving member. It is done.

  According to the first aspect of the present invention, in the driving device, the moving member (12) has a rod shape, and the flexible sandwiching portion (142) is provided in the vibrating member (14). The moving member (12) is sandwiched. For example, the biasing member is engaged with the vibration member (14) and the flexible sandwiching portion (142) to press the flexible sandwiching portion against the moving member (12). You may comprise from the spring (15; 15A) which generate | occur | produces pressing force. It is preferable that the vibration member (14) has a groove (14a) having a V-shaped cross section at a frictional joint between the vibration member and the moving member.

  According to the second aspect of the present invention, in the drive device, the vibration member (22) has a rod shape, and the flexible sandwiching portion (242) is provided on the moving member (24). The vibration member (22) is sandwiched. The urging member is engaged with, for example, the moving member (24) and the flexible pinching portion (242), and presses the flexible pinching portion against the vibrating member (22). You may comprise from the spring (25) which generate | occur | produces pressing force. The moving member (24) preferably has a groove (24a) having a V-shaped cross section at a frictional joint between the moving member and the vibrating member.

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

  In the present invention, one of the vibrating member and the moving member has a flexible sandwiching portion that sandwiches the other of the vibrating member and the moving member by elasticity, and the biasing member has the flexible sandwiching portion as the other of the vibrating member and the moving member. Since the frictional force is applied between the vibrating member and the moving member, the assembly can be simplified, and the number of parts and the cost can be reduced.

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

  A driving apparatus 10 according to a first embodiment of the present invention will be described with reference to FIG. 1A is a plan view of the driving device 10, and FIG. 1B is a front view of the driving device 10. Here, as shown in FIG. 1, an orthogonal coordinate system (X, Y, Z) is used. In the state shown in FIG. 1, in the Cartesian coordinate system (X, Y, Z), the X axis is the left-right direction (width direction), the Y axis is the front-rear direction (depth direction), and the Z axis is the up-down direction ( Height direction).

  The illustrated driving device 10 is used, for example, as a lens driving unit of an autofocus lens driving unit. In that case, in the example shown in FIG. 1, the vertical direction Z is the optical axis direction of the lens.

  The illustrated driving device 10 is disposed in a housing (not shown). The housing includes a cup-shaped upper cover (not shown) and a lower base (not shown). A stationary member (weight) 11 is mounted on the lower base of the housing. The upper surface of the upper cover has a cylindrical portion (not shown) whose central axis is the optical axis of the lens. On the other hand, although not shown, an image sensor arranged on the substrate is mounted in the center of the lower base. This imaging device captures a subject image formed by a movable lens (described later) and converts it into an electrical signal. The imaging device is configured by, for example, a CCD (charge coupled device) type image sensor, a CMOS (complementary metal oxide semiconductor) type image sensor, or the like.

  In the housing, a guide shaft (not shown) is provided at a position facing the driving device 10 with a movable lens barrel (not shown) interposed therebetween. The guide shaft extends in parallel with the optical axis of the lens. The upper end of the guide shaft is fixed to the upper surface of the upper cover of the casing, and the lower end is fixed to the lower base of the casing. A rod-shaped moving shaft (moving member) 12 is provided on the opposite side of the guide shaft with the optical axis of the lens interposed therebetween. That is, the guide shaft and the moving shaft 12 are arranged at rotationally symmetric positions around the optical axis of the lens.

  Note that the autofocus lens driving unit includes a lens movable unit and a lens driving unit. The lens driving unit drives the lens moving unit as described later while supporting the lens moving unit slidably in the optical axis direction of the lens. The lens movable portion includes the rod-shaped moving shaft (moving member) 12, and the lens driving portion includes a stationary member (weight) 11. The lens movable part includes a driven member 17. The driven member 17 is coupled to one end of the moving member 12 via a connecting member 18.

  The drive device 10 (lens drive unit) includes a laminated piezoelectric element 13 that functions as an electromechanical conversion element, the columnar stationary member (weight) 11, and a vibration member 14. The laminated piezoelectric element 13 expands and contracts in the optical axis direction of the lens. The laminated piezoelectric element 13 has a structure in which a plurality of piezoelectric layers are laminated in the optical axis direction of the lens. The laminated piezoelectric element 13 has a first end (lower end) 13a and a second end (upper end) 13b that face each other in the expansion / contraction direction. The stationary member (weight) 11 is coupled to the first end (lower end) 13a of the laminated piezoelectric element 13 with an adhesive or the like. The vibration member 14 is attached to the second end (upper end) 13b of the laminated piezoelectric element 13 with an adhesive or the like. In the illustrated example, the vibration member 14 is directly coupled to the second end portion 13 b of the multilayer piezoelectric element 13, but any member is present between the vibration member 14 and the second end portion 13 b of the multilayer piezoelectric element 13. It may be interposed. A combination of the laminated piezoelectric element 13 and the stationary member 11 is called a piezoelectric unit.

  The rod-shaped moving shaft (moving member) 12 is frictionally coupled to the vibrating member 14. In the vibration member 14, a groove 14 a having a V-shaped cross section is formed at a friction coupling portion between the vibration member 14 and a rod-shaped moving shaft (moving member) 12.

  The vibration member 14 has a flexible sandwiching portion 142 that sandwiches the moving member 12 by elasticity. The driving device 10 (lens driving unit) includes a spring 15 for pressing (biasing) a rod-shaped moving shaft (moving member) 12 against the vibration member 14. That is, the spring 15 is engaged with the vibration member 14 and the flexible sandwiching portion 142 to generate a pressing force that presses the flexible sandwiching portion 142 against the moving member 12. In other words, the spring 15 acts as a biasing unit that biases the flexible sandwiching portion 142 to the moving member 12 and applies a frictional force between the vibrating member 14 and the moving member 12.

  The vibration member 14 is provided with a pair of locking grooves 14 b for holding the spring 15. Both ends 15a of the spring 15 are engaged with the vibration member 14 by the pair of locking grooves 14b, and extend from both ends 15a to the flexible sandwiching portion 142 side. The spring 15 has a contact portion 15b that contacts the flexible sandwiching portion 142 at the center thereof. Accordingly, the vibration member 14 and the flexible sandwiching portion 142 are pressed against the rod-shaped moving shaft (moving member) 12 by the spring 15. As a result, the rod-shaped moving shaft (moving member) 12 is stably friction-coupled to the vibrating member 14.

  More specifically, a flexible sandwiching portion 142 is sandwiched between the moving member 12 and the spring 15. This is because the deterioration of the pressing force due to the frictional wear of the spring 15 is eliminated, and the change of the frictional force due to the frictional wear of the spring 15 is eliminated. In order to prevent frictional wear of the flexible sandwiching portion 142, the surface of the flexible sandwiching portion 142 is desirably smooth.

  Further, in the vibration member 14, a groove 14 a having a V-shaped cross section is formed in the friction coupling portion between the vibration member 14 and the moving member 12. By the bilinear contact with the moving member 12 by the groove 14a having a V-shaped cross section of the vibration member 14, the contact state of the frictional coupling portion is stabilized, friction drive with good reproducibility is obtained, and the uniaxial moving body of the moving member 12 is obtained. As a result, there is an effect of improving the straight mobility. The angle of the groove 12a having a V-shaped cross section is desirably in the range of 30 degrees to less than 180 degrees.

  Further, the vibration member 14 and the flexible sandwiching portion 142 are pressed against the moving member 12 by the spring 15. Thereby, stable line contact is enabled by pressing the groove 14 a having a V-shaped cross section of the vibration member 14 and the flexible sandwiching portion 142 against the moving member 12. The pressing force by the spring 15 is desirably in the range of 5 to 100 gf.

  Thus, in this embodiment, the vibration member 14 has the flexible sandwiching portion 142. That is, the vibration member 14 has an integrated structure in which one end of the flexible sandwiching portion 142 is connected to the vibration member 14 by the connecting portion 144. The connecting portion 144 has a shape that easily deforms the flexible sandwiching portion 142 in the pressing direction by elastic deformation.

  For this reason, the drive device 10 according to the present embodiment does not require a separate pad that is necessary for the conventional drive device. Thereby, the assembly can be simplified, the number of parts can be reduced, and the cost can be reduced.

  Next, the current supplied to the laminated piezoelectric element 13 and the displacement generated in the laminated piezoelectric element 13 will be described with reference to FIG. FIG. 2 is the same as that shown in FIG. 2A and 2B show a change in current supplied to the laminated piezoelectric element 13 by a drive circuit (not shown) and a displacement of the laminated piezoelectric element 13, respectively.

  As shown in FIG. 2A, a large current (positive direction) and a predetermined constant current (negative direction) are alternately passed through the laminated piezoelectric element 13. In such a situation, as shown in FIG. 2B, the laminated piezoelectric element 13 has a sudden displacement (elongation) corresponding to a large current (positive direction) and a gentle corresponding to a constant current (negative direction). Displacement (shrinkage) occurs alternately.

  That is, a rectangular wave current is applied to the laminated piezoelectric element 13 (FIG. 2A), and a sawtooth-like displacement (expansion / contraction) is generated with respect to the laminated piezoelectric element 13 (FIG. 2B).

  The operation of the driving apparatus 10 will be described with reference to FIG. 1 in addition to FIG. First, an operation when the lens movable portion is moved downward along the vertical direction Z will be described.

  First, as shown in FIG. 2A, when a large current in the positive direction is passed through the laminated piezoelectric element 13, the laminated piezoelectric element 13 rapidly undergoes an elongation displacement in the thickness direction as shown in FIG. . As a result, the vibration friction portion 13 rapidly moves upward along the optical axis direction (vertical direction Z) of the lens. At this time, the moving member 12 (lens movable portion) overcomes the frictional force between the vibration member 14 and the rod-shaped moving shaft (moving member) 12 by the inertial force, and remains substantially in that position. do not do.

  Next, as shown in FIG. 2A, when a constant current in the negative direction is passed through the multilayer piezoelectric element 13, the multilayer piezoelectric element 13 is gradually contracted in the thickness direction. As a result, the vibration member 14 moves gently downward along the optical axis direction (vertical direction Z) of the lens. At this time, since the vibrating member 14 and the rod-shaped moving shaft (moving member) 12 are coupled by the frictional force generated on the contact surface between them, the moving member 12 (the lens movable portion) is substantially combined with the vibrating member 14. In particular, it moves downward along the optical axis direction (vertical direction Z) of the lens.

  In this way, a large current in the positive direction and a predetermined constant current in the negative direction are alternately supplied to the laminated piezoelectric element 13 to alternately generate an expansion displacement and a contraction displacement in the laminated piezoelectric element 13, thereby A lens holding frame (not shown) can be continuously moved downward along the lens optical axis direction (vertical direction Z).

  In order to move the moving member 12 (lens movable portion) upward along the lens optical axis direction (vertical direction Z), a negative current in the laminated piezoelectric element 13 and a predetermined value in the positive direction are reversed. This can be achieved by alternately passing a constant current.

  Next, the laminated piezoelectric element 13 will be described. The laminated piezoelectric element 13 has a rectangular parallelepiped shape, and the element size is 0.9 [mm] × 0.9 [mm] × 1.5 [mm]. A low Qm material such as PZT is used as the piezoelectric material. The laminated piezoelectric element 13 is manufactured by laminating 50 layers of piezoelectric materials having a thickness of 20 [μm] and internal electrodes having a thickness of 2 [μm] alternately in a comb shape. The effective internal electrode size of the laminated piezoelectric element 13 is 0.6 [mm] × 0.6 [mm]. In other words, a ring-shaped dead zone portion (clearance) having a width of 0.15 [mm] exists in the peripheral portion located outside the effective internal electrode of the laminated piezoelectric element 13.

  The spring as the urging member is not limited to that shown in FIG.

  FIG. 3 is a modification of the drive device shown in FIG. Therefore, the reference numeral of 10A is attached to the driving device. The illustrated driving apparatus 10A has the same configuration as the driving apparatus 10 shown in FIG. 1 and operates except that the shape of the spring is different from that shown in FIG. Therefore, the reference numeral 15A is attached to the spring. Components having the same functions as those shown in FIG. 1 are denoted by the same reference numerals, and description thereof will be omitted for the sake of simplicity.

  One end 15 a of the spring 15 </ b> A is engaged with a corner of the vibration member 14. The spring 15 </ b> A extends from the one end 15 a along the outer peripheral wall of the vibration member 14 to the flexible sandwiching portion 142 side. The spring 15 has a contact portion 15b that contacts the flexible sandwiching portion 142 on the other end side. As a result, the vibration member 14 and the flexible sandwiching portion 142 are pressed against the rod-shaped moving shaft (moving member) 12 by the spring 15A. As a result, the rod-shaped moving shaft (moving member) 12 is stably friction-coupled to the vibrating member 14.

  With reference to FIG. 4, the drive device 20 by the 2nd Embodiment of this invention is demonstrated. 4A is a plan view of the driving device 20, and FIG. 4B is a front view of the driving device 20. Here, as shown in FIG. 4, an orthogonal coordinate system (X, Y, Z) is used. In the state shown in FIG. 4, in the Cartesian coordinate system (X, Y, Z), the X axis is the left-right direction (width direction), the Y axis is the front-rear direction (depth direction), and the Z axis is the vertical direction ( Height direction).

  The illustrated driving device 20 is used as a lens driving unit of an autofocus lens driving unit, for example. In that case, in the example shown in FIG. 4, the vertical direction Z is the optical axis direction of the lens.

  The illustrated driving device 20 is disposed in a housing (not shown). The housing includes a cup-shaped upper cover (not shown) and a lower base (not shown). A stationary member (weight) 21 is mounted on the lower base of the housing. The upper surface of the upper cover has a cylindrical portion (not shown) whose central axis is the optical axis of the lens. On the other hand, although not shown, an image sensor arranged on the substrate is mounted in the center of the lower base. This imaging device captures a subject image formed by a movable lens (described later) and converts it into an electrical signal. The imaging device is configured by, for example, a CCD (charge coupled device) type image sensor, a CMOS (complementary metal oxide semiconductor) type image sensor, or the like.

  In the housing, a guide shaft (not shown) is provided at a position facing the driving device 20 with a movable lens barrel (not shown) interposed therebetween. The guide shaft extends in parallel with the optical axis of the lens. The upper end of the guide shaft is fixed to the upper surface of the upper cover of the casing, and the lower end is fixed to the lower base of the casing. A rod-shaped vibrating member 22 is provided on the opposite side of the guide shaft with the optical axis of the lens interposed therebetween. That is, the guide shaft and the vibration member 22 are arranged at rotationally symmetric positions around the optical axis of the lens.

  Note that the autofocus lens driving unit includes a lens movable unit and a lens driving unit. The lens driving unit drives the lens moving unit as described later while supporting the lens moving unit slidably in the optical axis direction of the lens. The lens driving unit includes a stationary member (weight) 21 and a rod-shaped vibrating member 22. The lens movable part includes a driven member 27. The driven member 27 is coupled to a moving member 24 described later.

  The driving device 20 (lens driving unit) includes a laminated piezoelectric element 23 that functions as an electromechanical conversion element, the columnar stationary member (weight) 21, and a rod-shaped vibrating member 22. The laminated piezoelectric element 23 expands and contracts in the optical axis direction of the lens. The laminated piezoelectric element 23 has a structure in which a plurality of piezoelectric layers are laminated in the optical axis direction of the lens. The laminated piezoelectric element 23 has a first end (lower end) 23a and a second end (upper end) 23b that face each other in the expansion / contraction direction. The stationary member (weight) 21 is coupled to the first end (lower end) 23a of the laminated piezoelectric element 23 with an adhesive or the like. The rod-shaped vibrating member 22 is attached to the second end (upper end) 23b of the laminated piezoelectric element 23 with an adhesive or the like. In the illustrated example, the rod-shaped vibration member 22 is directly coupled to the second end 23 b of the multilayer piezoelectric element 23, but between the rod-shaped vibration member 22 and the second end 23 b of the multilayer piezoelectric element 23. Some members may intervene. The combination of the laminated piezoelectric element 23 and the stationary member 21 is called a piezoelectric unit.

  The moving member 24 is frictionally coupled to the rod-shaped vibrating member 22. In the moving member 24, a groove 24 a having a V-shaped cross section is formed at a frictional coupling portion between the moving member 24 and the rod-shaped vibrating member 22.

  The moving member 24 has a flexible sandwiching portion 242 that sandwiches the rod-shaped vibrating member 22 by elasticity. The driving device 20 (lens driving unit) includes a spring 25 for pressing (urging) the rod-shaped vibrating member 22 against the moving member 24. That is, the spring 25 is engaged with the moving member 24 and the flexible sandwiching portion 242 to generate a pressing force that presses the flexible sandwiching portion 242 against the vibration member 22. In other words, the spring 25 acts as a biasing unit that biases the flexible sandwiching portion 242 to the vibration member 22 and applies a frictional force between the moving member 24 and the vibration member 22.

  The moving member 24 is provided with a pair of locking grooves 24 b for holding the spring 25. Both ends 25a of the spring 25 are engaged with the moving member 24 by the pair of locking grooves 24b, and extend from the both ends 25a to the flexible sandwiching portion 242 side. The spring 25 has a contact portion 25b that contacts the flexible sandwiching portion 242 at the center thereof. Accordingly, the moving member 24 and the flexible sandwiching portion 242 are pressed against the rod-shaped vibrating member 22 by the spring 25. As a result, the moving member 24 is stably frictionally coupled to the rod-shaped vibrating member 22.

  More specifically, a flexible sandwiching portion 242 is sandwiched between the vibration member 22 and the spring 25. This is because the deterioration of the pressing force due to the frictional wear of the spring 25 is eliminated, and the change of the frictional force due to the frictional wear of the spring 25 is eliminated. In addition, in order to prevent frictional wear of the flexible sandwiching portion 242, it is desirable that the surface of the flexible sandwiching portion 242 be smooth.

  Further, in the moving member 24, a groove 24 a having a V-shaped cross section is formed in the friction coupling portion between the moving member 24 and the rod-shaped vibrating member 22. The bilinear contact with the vibration member 22 by the groove 24a having a V-shaped cross section of the moving member 24 has an effect that the contact state of the friction coupling portion is stabilized and friction drive with good reproducibility can be obtained. The angle of the V-shaped groove 24a is preferably in the range of 30 degrees to less than 180 degrees.

  Further, the movable member 24 and the flexible sandwiching portion 242 are pressed against the rod-shaped vibration member 22 by the spring 25. Thereby, stable line contact is enabled by pressing the groove 24 a having a V-shaped cross section of the moving member 24 and the flexible sandwiching portion 242 against the vibration member 22. The pressing force by the spring 25 is desirably in the range of 5 to 100 gf.

  Thus, in this embodiment, the moving member 24 has the flexible sandwiching portion 242. That is, the moving member 24 has an integrated structure in which one end of the flexible sandwiching portion 242 is connected to the moving member 24 by the connecting portion 244. The connecting portion 244 has a shape that easily deforms the flexible sandwiching portion 242 in the pressing direction by elastic deformation.

  For this reason, the drive device 20 according to the present embodiment does not require a separate pad that is necessary for the conventional drive device. Thereby, the assembly can be simplified, the number of parts can be reduced, and the cost can be reduced.

  Although the present invention has been described with reference to preferred embodiments, it is obvious that various modifications can be made by those skilled in the art without departing from the spirit of the present invention. For example, in the above embodiment, a spring is used as the urging member, but it is needless to say that an urging member other than the spring may be used.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the drive device by the 1st Embodiment of this invention, (A) is a top view of a drive device, (B) is a front view of a drive device. It is a wave form diagram for demonstrating the electric current supplied to a laminated piezoelectric element, and the displacement which generate | occur | produces in a laminated piezoelectric element. FIGS. 2A and 2B are diagrams illustrating a modification of the drive device illustrated in FIG. 1, in which FIG. 1A is a plan view of the drive device, and FIG. 2B is a front view of the drive device. It is a figure which shows the drive device by the 2nd Embodiment of this invention, (A) is a top view of a drive device, (B) is a front view of a drive device.

Explanation of symbols

10, 10A Drive device 11 Stationary member (weight)
12 Rod-shaped moving part (moving member)
13 Multilayer piezoelectric element (electromechanical transducer)
13a First end (lower end)
13b Second end (upper end)
DESCRIPTION OF SYMBOLS 14 Vibrating member 14a Groove of V-shaped cross section 14b Locking groove 142 Flexible sandwiching portion 144 Connection portion 15, 15A Spring (biasing member)
20 Drive device 21 Stationary member (weight)
22 Rod-shaped vibrating member 23 Multilayer piezoelectric element (electromechanical transducer)
23a First end (lower end)
23b Second end (upper end)
24 moving member 24a groove having V-shaped cross section 24b locking groove 242 flexible sandwiching portion 244 connecting portion 25 spring (biasing member)

Claims (7)

An electromechanical transducer having a pair of ends opposed to each other in the direction of expansion and contraction; a vibration member attached to one of the pair of ends of the electromechanical transducer; a moving member frictionally coupled to the vibration member; In the drive device in which the moving member is movable in the expansion / contraction direction of the electromechanical conversion element,
One of the vibrating member and the moving member has a flexible sandwiching portion that sandwiches the other of the vibrating member and the moving member by elasticity,
A biasing member that biases the flexible sandwiching portion to the other of the vibrating member and the moving member and applies a frictional force between the vibrating member and the moving member is provided. Drive device.   The drive device according to claim 1, wherein the moving member has a rod shape, and the flexible sandwiching portion is provided in the vibration member to sandwich the moving member.   The biasing member is configured by a spring that generates a pressing force for engaging the vibrating member and the flexible sandwiching portion to press the flexible sandwiching portion against the moving member. The drive device according to claim 2.   4. The driving device according to claim 2, wherein the vibration member has a groove having a V-shaped cross section at a frictional coupling portion between the vibration member and the moving member. 5.   The drive device according to claim 1, wherein the vibration member has a rod shape, and the flexible sandwiching portion is provided on the moving member to sandwich the vibration member.   The biasing member is configured by a spring that generates a pressing force for engaging the moving member and the flexible sandwiching portion to press the flexible sandwiching portion against the vibration member. The drive device according to claim 5.   The drive device according to claim 5, wherein the moving member has a groove having a V-shaped cross section at a frictional coupling portion between the moving member and the vibration member.

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