JP2009296753A - Drive unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a drive unit that correctly holds a vibration member and is suitable for miniaturization. <P>SOLUTION: The drive unit 1 includes an electro-mechanical conversion element 4 that expands and contracts when voltage is applied, a vibration member 5 that extends in the expansion and contraction direction of the electro-mechanical conversion element 4, fixed in its one end to the electro-mechanical conversion element 4, and is reciprocatingly displaced by the expansion and contraction of the electro-mechanical conversion element 4, a friction engaged member 6 that is friction-engaged with the vibration member 5, a supporting member 7 that extends from the vibration member 5 in the direction perpendicular to the displacement direction of the vibration member 5, and a base member 2 that holds a portion away from the vibration member 5 of the supporting member 7. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a drive device, and more particularly to a drive device that slides and displaces a friction engagement member by asymmetric vibration.

  2. Description of the Related Art A vibration type driving device is known in which an axial vibration member is vibrated asymmetrically and a friction engagement member that frictionally engages the vibration member is slidably displaced. In a vibration type driving device, in order to ensure driving accuracy, it is necessary to hold the vibration member accurately in the vibration direction.

  In the driving device disclosed in Patent Document 1, the vibration member is inserted into a through hole provided in the wall of the frame, and slides in the through hole. In this configuration, in consideration of assemblability and the like, it is necessary to make the through hole larger than the vibrating member to some extent, and the vibrating member cannot be held with high accuracy.

Therefore, in the drive device of Patent Document 2, the vibration member is pressed into the groove formed in the fixed frame by the leaf spring, and the vibration member is vibrated along the groove. However, in a small drive device, it is difficult to accurately form a fine spring that presses the vibration member into the groove.
JP 7-274543 A Japanese Patent Laid-Open No. 2007-274757

  In view of the above problems, an object of the present invention is to provide a drive device suitable for downsizing that can accurately hold a vibrating member.

  In order to solve the above problems, a driving device according to the present invention includes an electromechanical conversion element that expands and contracts when a voltage is applied, and extends in the expansion and contraction direction of the electromechanical conversion element, and one end is fixed to the electromechanical conversion element. A vibration member that reciprocally displaces by expansion and contraction of the electromechanical transducer, a friction engagement member that frictionally engages the vibration member, a support member that extends from the vibration member in a displacement direction of the vibration member, and the support And a base member that holds a portion of the member away from the vibration member.

  According to this configuration, the vibration member is supported by the support member, and the vibration member can be vibrated within the range of elastic deformation of the support member. Since the support member is fixed or integrally formed with the vibration member, the vibration member can be held with high accuracy. Further, in this configuration, since a pressing mechanism such as a spring is not necessary, the size can be easily reduced. Furthermore, since the vibration member does not slide with respect to other components, there is no performance change due to a change in the friction state.

  In the driving device of the present invention, the support member may extend from an end portion of the vibration member opposite to the electromechanical conversion element.

  According to this structure, since it does not interfere with the electromechanical transducer, it is easy to fix the support member to the vibration member.

  In the driving device of the present invention, the support member may be interposed between the electromechanical conversion element and the vibration member.

  According to this configuration, since the electromechanical conversion element and the vibration member are sandwiched, assembly is easy, and reliable fixing can be performed.

  In the driving device of the present invention, the support member may be a thin metal plate in the displacement direction of the vibration member.

  According to this configuration, by fixing the rigid thin metal plate to the end face of the vibration member, it is possible to hold the vibration member with high accuracy and enable effective vibration of the vibration member.

  In the driving device of the present invention, the support member may be bonded to the vibration member.

  According to this configuration, the processing accuracy of the vibration member is not impaired.

  In the driving device of the present invention, the support member may be bonded to an end surface of the vibration member.

  According to this configuration, the support member can be easily bonded, and sufficient bonding strength and assembly accuracy can be ensured.

  In the present invention, the vibration member is held by a holding member extending in a direction orthogonal to the displacement direction, and the vibration member can be displaced (vibrated) by elastic deformation of the holding member. Therefore, the structure for holding the vibration member is simple, but the accuracy is high, and the size can be easily reduced.

Embodiments of the present invention will now be described with reference to the drawings.
FIG. 1 shows a configuration of a driving apparatus 1 according to the present invention. The driving device 1 includes an elongated U-shaped base member 2 opened upward, a weight 3 fixed on the lower side of the base member 2, and a piezoelectric element (electromechanical transducer element) fixed on the weight 3. ) 4, a columnar vibration member 5 that is fixed upright on the piezoelectric element 4, a friction engagement member 6 that engages the vibration member 5 by frictional force, and an upper end of the vibration member 5. From a belt-shaped stainless steel plate having a thickness of about 0.1 mm, for example, extending on both sides from the vibration member 5 in a direction perpendicular to the axial direction of the vibration member and having tip portions fixed on both open ends of the base member 2. And a supporting member 7. These components are fixed to each other with an adhesive except for the frictional engagement member 6.

  The piezoelectric element 4 is applied with a periodic drive voltage and expands and contracts in the vertical direction to reciprocate (displace) the vibration member 5 in the axial direction. The friction engagement member 6 moves together with the vibration member 5 when the vibration member 5 moves slowly. However, when the vibration member 5 moves steeply, the friction engagement member 6 slides and displaces with respect to the vibration member 5 due to inertial force. The support member 7 determines the position of the tip of the vibration member 5, but as shown by a two-dot chain line, the support member 7 bends up and down to allow vertical displacement of the tip of the vibration member 5.

  The support member 7 extends symmetrically in a direction perpendicular to the displacement direction of the vibration member 5 (the expansion / contraction direction of the piezoelectric element 4), and both ends are fixed to the base member 2. Therefore, the support member 7 does not change the horizontal position of the central portion that holds the tip of the vibration member 5 in order to maintain the balance of tension on both sides, and the upper end of the vibration member 5 is displaced only in the vertical direction. Therefore, the vibration member 5 is prevented from being tilted. In order to enable elastic deformation of the support member 7, the support member 7 needs to be held by the base member 2 at a position away from the vibration member 5 to some extent.

  As described above, in the driving device 1, one end of the vibration member 5 is held by the base portion 2 via the weight 3 and the piezoelectric element 4, and the other end via the support member 7. For this reason, since the vibration member 5 does not tilt, the reproducibility of the sliding displacement of the friction engagement member 6 due to vibration caused by expansion and contraction of the piezoelectric element 4 is high, and the driving accuracy is high. Further, since the vibration member 5 is held by the plate-like support member 7 fixed with an adhesive, the holding structure is simple and the size can be easily reduced.

  FIG. 2 shows the configuration of the drive device 1a according to the second embodiment of the present invention. In the following description, the same components as those described above are denoted by the same reference numerals, and redundant description is omitted.

  In the driving device 1 a, the base member 2 a has two wall portions 8 and 9 that extend parallel to the piezoelectric element 4 and the vibration member 7 and are orthogonal to the vibration member 7. V-grooves 8 a and 9 a for receiving the vibration member 5 are formed in the walls 8 and 9. In the figure, the frictional engagement member 6 is omitted for simplification.

  The driving device 1a fixes the support member 7 with an adhesive 10 placed on the wall portion 9 while pressing the vibration member 5 against the V grooves 8a and 9a. Accordingly, the displacement direction of the vibration member 5 can be accurately determined so as to slide in the V grooves 8a and 9a. In the driving device 1a, the weight 3 is not fixed.

  In the driving device 1a, when the support member 7 is fixed, the space of the support member 7 is elastically deformed by leaving a gap between the support member 7 and the wall portion 9 by leaving the thickness of the adhesive 10. Secure. Of course, instead of placing the adhesive 10, a convex portion may be provided on the wall portion 9 or a spacer may be sandwiched.

  FIG. 3 shows the configuration of the drive device 1b according to the third embodiment of the present invention. Also in this embodiment, the friction engagement member 6 is omitted.

  The drive device 1 b according to the present embodiment includes a support member 11 sandwiched between the piezoelectric element 4 and the vibration member 5, and a support member 12 bonded to the tip of the vibration member 5. The support members 11 and 12 extend from the end face of the vibration member 5 in parallel to each other only in one direction perpendicular to the displacement direction of the vibration member 5, and the tips are bent at a right angle and attached to the base member 2b. Worn.

  In this embodiment, since the vibration member 5 is held at both ends by the support members 11 and 12, the holding strength of the vibration member 5 is high. Further, since the support members 11 and 12 are cantilevered, they are easily elastically deformed, and the driving loss of the driving device 1b can be reduced.

  When the support member 11 is sandwiched between the piezoelectric element 4 and the vibration member 5, since the elasticity in the thickness direction of the support member 11 affects the drive characteristics of the drive device, the support member 11 is thin and has an elastic modulus. It is preferable to use a low metal.

  Moreover, in this invention, you may use the wire-shaped support member 13 like 4th-6th embodiment which shows a characteristic part in FIG. 4 thru | or FIG. The support member 13 may be fitted into a groove 14 provided on the end surface of the vibration member 5 or may be inserted into the support hole 15 formed in the vibration member 5.

  Further, as in the seventh embodiment of the present invention shown in FIG. 7, the vibration member 16, the support members 17 and 18, and the base member 19 may be molded integrally. In the present embodiment, the rectangular columnar vibration member 16, the support members 17 and 18 extending from both ends of the vibration member 16, and the base member 19 connected to the tips of the support members 17 and 18 are integrally molded with resin. ing. The support members 17 and 18 are formed with holes 17a and 18a that reduce rigidity in order to facilitate deformation that allows the vibration member 16 to be displaced in the axial direction.

  Of course, the vibration material, the support member and the base member may be machined together by machining a block-shaped material. Further, only the vibration member and the support member, or only the base member and the support member may be integrally formed.

The front view of the drive device of 1st Embodiment of this invention. The disassembled perspective view of the drive device of 2nd Embodiment of this invention. The disassembled perspective view of the drive device of 3rd Embodiment of this invention. The fragmentary perspective view of the drive device of 4th Embodiment of this invention. The fragmentary perspective view of the drive device of 5th Embodiment of this invention. The fragmentary perspective view of the drive device of 6th Embodiment of this invention. The fragmentary perspective view of the drive device of 7th Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Drive apparatus 2 ... Base member 3 ... Weight 4 ... Piezoelectric element (electromechanical conversion element)
DESCRIPTION OF SYMBOLS 5 ... Vibration member 6 ... Friction engagement member 7 ... Support member 11 ... Support member 12 ... Support member 13 ... Support member 16 ... Vibration member 17 ... Support member 18 ... Support member 19 ... Base member

Claims (6)

An electromechanical transducer that expands and contracts when a voltage is applied;
A vibrating member that extends in the expansion / contraction direction of the electromechanical conversion element, has one end fixed to the electromechanical conversion element, and reciprocally displaces by expansion and contraction of the electromechanical conversion element;
A friction engagement member frictionally engaging the vibration member;
A support member extending from the vibrating member in a direction perpendicular to the direction of displacement of the vibrating member;
And a base member that holds a portion of the support member away from the vibration member.   The drive device according to claim 1, wherein the support member extends from an end portion of the vibration member opposite to the electromechanical conversion element.   The drive device according to claim 1, wherein the support member is interposed between the electromechanical transducer and the vibration member.   The drive device according to claim 1, wherein the support member is a thin metal plate in a displacement direction of the vibration member.   The drive device according to claim 1, wherein the support member is bonded to the vibration member.   The drive device according to claim 5, wherein the support member is bonded to an end surface of the vibration member.

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