JP2009142121A - Piezoelectric actuator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric actuator which is achieved by compactifying a pre-pressurizing mechanism in an SIDM (Smooth Impact Drive Mechanism). <P>SOLUTION: The piezoelectric actuator 1 includes a piezoelectric element 3, a contactor 5 disposed on one end of the piezoelectric element 3, a driven object 7 disposed at one side of the contacttor 5, and a pre-pressure applying unit 9 which is disposed at the other side of the contactor 5 and presses the contactor 5 toward the driven object 7. It is preferable that the contact surface 29 of the contactor 5 be a spherical surface, that the driven object 7 extend longer than the spherical surface in the direction of driving, and that the other end of the piezoelectric element 3 be supported rotatably. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a piezoelectric actuator.

  As a drive device using a piezoelectric element, there is a piezoelectric actuator using a smooth impact drive mechanism (SIDM). For example, Patent Document 1 uses the SIDM to realize CCD shift type camera shake correction of a camera. The principle of SIDM is as follows. First, a rod-like drive shaft is extended from a predetermined fixed support portion via a piezoelectric element, and a driven body to be driven is brought into contact with the drive shaft. When a sawtooth voltage waveform is input to the piezoelectric element, the piezoelectric element expands slowly when extended, and rapidly shortens when shortened. As a result, the drive shaft also moves slowly in one direction and moves rapidly in the opposite direction. When the drive shaft moves slowly, the driven body moves integrally with the drive shaft by frictional force, and when the drive shaft moves suddenly, the driven body moves to the spot due to inertia. Try to stay. In this manner, the driven body is moved in one direction according to the direction of the input sawtooth voltage waveform.

However, in the piezoelectric actuator described above, preload is applied from the opposite side of the drive shaft in the driven body, and the driven body is pressed against the drive shaft. For this reason, a complicated and large preload mechanism is required so that the preload can be continuously applied even if the driven body continues to move.
JP 2006-81348 A

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a piezoelectric actuator capable of reducing the size by making the preload mechanism compact in SIDM.

  In order to solve the above-described problems, a piezoelectric actuator according to the present invention includes a piezoelectric element, a contact provided on one end side of the piezoelectric element, a driven body provided on one side of the contact, A preload applying portion that is provided on the other side of the contact and urges the contact toward the driven body.

  Further, the contact surface of the contactor is formed of a protruding surface, the driven body extends longer than the protruding surface in the driving direction, and the other end side of the piezoelectric element is rotatable. It is preferred that it is supported.

  The driven body may be a disk member that is rotatably supported, and the driven body may be in contact with the protruding surface on an annular side surface of the disk member. Alternatively, the driven body may be a rectangular parallelepiped or a sphere.

  According to the present invention, the preload applying portion is provided on the opposite side of the driven body across the contact, and the preload directed to the driven body is applied to the contact so that the driven body moves. Even if it continues, it is only necessary to apply a preload to the contact, and the preload applying portion can be made compact and the piezoelectric actuator can be miniaturized.

  In addition, the contact that abuts against the driven body is a spherical surface, and the driven body extends in the driving direction longer than the contact, and the contact of the piezoelectric element Since the opposite side is rotatably supported, it is possible to avoid an excessive shearing force from acting on the piezoelectric element even if a preload is applied to the contact instead of the driven body.

  The other features of the present invention and the operational effects thereof will be described in more detail with reference to the accompanying drawings.

  Embodiments of a SIDM piezoelectric actuator according to the present invention will be described below with reference to the accompanying drawings. In the drawings, the same reference numerals indicate the same or corresponding parts.

  FIG. 1 shows the configuration of the SIDM piezoelectric actuator according to the present embodiment. The piezoelectric actuator 1 includes a piezoelectric element 3, a contact 5, a driven body 7, and a preload applying unit 9. The contact 5 is provided on one end side of the piezoelectric element 3. The other end of the piezoelectric element 3 is rotatably supported by a generally U-shaped frame 13 via a rotation support shaft 11. The driven body 7 is provided on one side of the contact 5. In the present embodiment, the driven body 7 is a disk member and is rotatably supported by the frame 13. The preload applying portion 9 is provided on the other side of the contact 5 and biases the contact 5 toward the driven body 7.

  Furthermore, based on FIG. 2, the periphery of a contactor and a preload provision part is demonstrated in detail. FIG. 2 is a diagram in which the contact and the preload applying portion are easily seen in FIG. 1 except for the frame and the driven body. A bracket portion 15 is provided on the other side of the piezoelectric element 3. The bracket portion 15 is generally L-shaped, and the piezoelectric element 3 is connected to one end side thereof. Further, a through hole 17 through which the rotation support shaft 11 is inserted is provided near the other end.

  The preload applying portion 9 includes a substantially rod-shaped main body portion 19 and a coil spring 21. The main body 19 extends substantially along the direction in which the piezoelectric elements 3 and the contacts 5 are arranged, and a through hole 23 is provided in the middle of the longitudinal direction. The main body 19 is rotatably supported with respect to the frame 13 by a shaft member (not shown) inserted through the through hole 23. A notch 25 is formed at the end of the main body 19, and one end side of the coil spring 21 is accommodated in the notch 25.

  The contact 5 is provided on one end side of the piezoelectric element 3 and has a main body 27 and a contact surface 29. The contact surface 29 is provided on one side of the main body 27, and a spring receiving surface 31 is formed on the other side of the main body 27. The other end side of the coil spring 21 is connected to the spring receiving surface 31. The contact surface 29 is configured by a protruding surface that protrudes from the base surface 33 of the main body 27, and is configured by a spherical surface as an example in the present embodiment. The contact surface 29 is in contact with the driven body 7 at the annular side surface 35 of the driven body 7 made of a disk member (see also FIG. 1). Further, the base surface 33 of the main body 27 is in a relationship facing the annular side surface 35 of the driven body 7, and is in a relationship of inclining with the spring receiving surface 31. Further, as can be understood from the spherical shape of the contact surface 29 and the annular shape of the annular side surface 35, the driven body 7 (annular side surface 35) is driven with respect to the contact 5 (contact surface 29). In this embodiment, it is in a relation of extending in the circumferential direction).

  Next, the operation of the piezoelectric actuator configured as described above will be described. As shown in FIG. 1, the contact 5 is in contact with the driven body 7, and preload is applied from the opposite direction of the driven body 7 by the preload applying section 9. When a sawtooth voltage waveform is input to the piezoelectric element 3, the piezoelectric element 3 expands slowly when extended and rapidly decreases when shortened. Alternatively, when a sawtooth voltage waveform that is inverted to that is input, the piezoelectric element 3 conversely expands rapidly when extended, and slowly decreases when shortened.

  Along with this, the contact 5 also moves slowly in one direction and moves abruptly in the opposite direction. Therefore, the driven body 7 is moved (rotated) by the frictional force when the contactor 5 moves slowly, and the driven body 7 is moved when the contactor 5 moves suddenly. 7 tries to stay in place due to inertia. In this way, the driven body 7 is rotated in one direction according to the direction of the input sawtooth voltage waveform.

  Further, as described above, in the existing SIDM, since the preload is applied to the driven body, a complicated and large preload mechanism is provided so that the preload can be continuously applied even if the driven body continues to move. Was needed. On the other hand, in the present invention, the preload applying portion 9 is provided on the opposite side of the driven body 7 with the contact 5 interposed therebetween, and a preload directed toward the driven body 7 is applied to the contact 5. Therefore, even if the driven body 7 continues to move, it is only necessary to apply a preload to the contact 5, and the preload applying portion 9 can be made compact as in the illustrated configuration and the above-described configuration, thereby reducing the size of the piezoelectric actuator. it can.

  Furthermore, in the existing SIDM, when preload is applied to the drive shaft that drives the driven body instead of the driven body, the drive shaft is a long rod and is fixed in a cantilever manner. Therefore, an excessive shearing force may act on the piezoelectric element as the position of the driven body with respect to the drive shaft changes. On the other hand, in the present embodiment, the contact surface 29 of the contact 5 that contacts the annular side surface 35 of the driven body 7 is formed of a spherical surface, and the driven body 7 is more than the contact 5. Since the piezoelectric element 3 is supported so as to extend long in the driving direction and the opposite side of the piezoelectric element 3 to the contact 5 is rotatably supported, a preload is applied to the contact 5 instead of the driven body 7. However, it is possible to avoid an excessive shearing force from acting on the piezoelectric element 3.

  Although the contents of the present invention have been specifically described with reference to the preferred embodiments, various modifications can be made by those skilled in the art based on the basic technical idea and teachings of the present invention. It is self-explanatory.

  For example, the piezoelectric actuator of the present invention is not limited to the driven body being rotationally driven, and can also be implemented as a linearly driven mode.

  In addition to the U-shape, the frame may adopt other forms such as a U-shape or a V-shape. The preload generation source in the preload application unit is not limited to the coil spring.

  In addition, the contact surface of the contact is not limited to a spherical surface, and may be any aspect configured by a protruding surface that partially contacts the driven body. For example, the surface of the pyramid, the cone Other surfaces are also possible.

  The driven body is not limited to the disk member, and may be configured as a flat body such as a rectangular parallelepiped or a plate-like body, or a curved body such as a sphere or an annular body.

It is a perspective view which shows the outline | summary of the piezoelectric actuator which concerns on embodiment of this invention. It is a perspective view which shows a contactor and a preload provision part clearly regarding this Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Piezoelectric actuator 3 Piezoelectric element 5 Contact 7 Driven body 9 Preload provision part 29 Contact surface

Claims (4)

A piezoelectric element;
A contact provided on one end of the piezoelectric element;
A driven body provided on one side of the contact;
A piezoelectric actuator comprising: a preload applying portion that is provided on the other side of the contact and biases the contact toward the driven body. The contact surface of the contact is composed of a protruding surface,
The driven body extends longer than the protruding surface in the driving direction,
The piezoelectric actuator according to claim 1, wherein the other end side of the piezoelectric element is rotatably supported. The driven body is a disk member supported rotatably,
The piezoelectric actuator according to claim 2, wherein the driven body is in contact with the protruding surface on an annular side surface of the disk member.   The piezoelectric actuator according to claim 2, wherein the driven body is a rectangular parallelepiped or a sphere.

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