JP2003047266A - Vibration wave drive - Google Patents

Abstract

(57) [Problem] To provide a small-sized, high-output and inexpensive vibration wave driving device. A vibrating body includes a disc-shaped elastic body d having a first elastic body a which is a small-diameter metal rod-shaped elastic body on an upper surface, and a metal having a larger outer diameter than the first elastic body a on a lower surface. There is a disk-shaped second elastic body b which is a rod-shaped elastic body, and a polygonal piezoelectric element c is sandwiched and fixed between them. In addition, the first elastic body a having a small diameter
Has a bolt structure at the lower portion, and has a structure to be screw-coupled to the second elastic body b. The diameter of the circumscribed circle of the piezoelectric element c is equal to the diameter of the second elastic body b.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration wave driving device such as a vibration wave motor, and more particularly to a structure of a vibration body.

[0002]

2. Description of the Related Art Generally, a vibration wave driving device such as a vibration wave motor has a vibrating body having a driving vibration as a basic structure, and includes, for example, the vibrating body and a contact body that makes pressure contact with the vibrating body. Are relatively moved by the drive vibration.

The vibrating body is generally composed of an elastic body and a piezoelectric element as an electro-mechanical energy conversion element, and for example, a position having a phase difference of 90 ° with respect to the elastic body. A piezoelectric element having a driving phase is arranged on the two driving phases, and a traveling wave is generated on the elastic body by applying an alternating signal of two phases having a phase difference of 90 ° to the two driving phases. The driving force is obtained by pressing and frictional force.

The vibration wave motor as such a vibration wave driving device has been applied to products such as driving a camera lens, and there are an annular type and a rod type.

[0005]

In the conventional rod-shaped vibration wave motor, there is a demand to make it smaller and to lower the cost. If the size is simply reduced to meet the demand, there is a problem that the output becomes small.

Therefore, in order to overcome this problem, if the vibrator is simply made small and the electro-mechanical energy conversion element has a circular cross section (axial symmetry) as in the conventional case, the electric
The electrode area of the mechanical energy conversion element becomes small, and a large force cannot be extracted.

The present invention has been made in view of such conventional problems, and an object of the present invention is to provide a small-sized, high-power and inexpensive vibration wave driving device.

[0008]

SUMMARY OF THE INVENTION According to the present invention, an electro-mechanical energy conversion element having a polygonal cross section orthogonal to the axial direction and a pair of circular cross sections orthogonal to the axial direction are formed. With a metal elastic body of, the electro-mechanical energy conversion element is arranged between the pair of metal elastic body,
A pair of metallic elastic bodies are fastened by a fastening means to have a rod-shaped vibrating body in which the electro-mechanical energy conversion element is sandwiched and fixed between the pair of metallic elastic bodies.

By thus making the cross section of the electro-mechanical energy conversion element polygonal, the electrode area can be increased, so that the electro-mechanical energy conversion element can be effectively utilized and high output can be taken out. Can
Low voltage can be achieved. With the reduction in voltage, a booster circuit or the like is not required, and the cost can be reduced, and an inexpensive vibration wave motor can be provided.

In order to achieve high efficiency, electricity-
The mechanical energy conversion element is configured such that the vibrating body excites two bending vibrations whose vibration directions are orthogonal to each other.

Further, in order to make the most effective use of the electro-mechanical energy conversion element, the electro-mechanical energy conversion element has a rectangular cross section.

Further, as a means for providing a difference in dynamic rigidity, a configuration is adopted in which the vertical-horizontal dimension ratio of the electro-mechanical energy conversion element is changed.

Further, the diameter of the circumscribed circle of the polygonal electric-mechanical energy conversion element and the diameter of the circular rod-shaped member should be the same so that the outer shapes can be easily assembled. Configured.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 1 shows a vibrating body of a vibration wave drive device according to a first embodiment of the present invention. FIG. 1A is a sectional view of the vibrating body, and FIG. 1B is a perspective view thereof.

The vibrating body according to the present embodiment has a disc-shaped elastic body d having a first elastic body a which is a metal rod-shaped elastic body having a small diameter on the upper surface, and an outer diameter smaller than that of the first elastic body a on the lower surface. There is a disk-shaped second elastic body b which is a large metal rod-shaped elastic body, and a polygonal piezoelectric element c is sandwiched and fixed between them. The lower part of the small-diameter first elastic body a has a bolt structure, and the second
It has a structure in which it is screwed to the elastic body b.

The diameter of the circumscribed circle of the piezoelectric element c and the diameter of the second elastic body b are the same.

(Second Embodiment) FIG. 2 shows a second embodiment of the present invention.
Of the embodiment, (a) is a cross-sectional view of the vibrating body, (b)
Is a perspective view thereof.

In this embodiment, the first elastic body a and the second elastic body a
The diameter of the elastic body b and the diameter of the circumscribed circle of the piezoelectric element c are configured to have the same length, and by combining the outer shapes, the vibrating body can be easily assembled.

(Third Embodiment) FIG. 3 shows a third embodiment of the present invention.
In the embodiment, (a) is a sectional view of the vibrating body, and (b) is a perspective view thereof.

The vibrating body of this embodiment uses a piezoelectric element c having a square cross section. By forming the piezoelectric element in a square shape, the electrode area can be made larger than that in the case of a circular shape, so that the piezoelectric element can be effectively used and a lower voltage can be achieved.

(Fourth Embodiment) FIG. 6 shows a fourth embodiment showing another shape of the piezoelectric element c. The cross-sectional shape of the piezoelectric element in the figure is (a) rectangular, (b) regular hexagonal,
(c) shows a square.

FIG. 7 shows the shape of the piezoelectric element c and the vibration direction thereof. In the case of the square shown in (a), two bending vibrations orthogonal to each other are excited, but the direction of the vibration is not uniquely determined.

On the other hand, in the case of the rectangle shown in (b), two bending vibrations orthogonal to each other are excited, and the vibration direction thereof has the property of being uniquely determined in the direction of the arrow in the figure. ing. If you take advantage of that property,
When it is desired to intentionally determine the vibration direction of the vibrating body, the vibration can be intentionally excited in the determined direction. Specifically, it can be easily implemented by changing the direction of the piezoelectric element c.

FIG. 4 relates to a method of manufacturing the piezoelectric element c. To make a piezoelectric element with a circular cross section, first,
A method is used in which a plurality of piezoelectric sheets are cut into squares from one sheet of piezoelectric material, and then the outer shape is processed into a circular shape. By using the square piezoelectric element, it is possible to save the time and effort for the outer shape processing and reduce the cost.

(Fifth Embodiment) FIG. 5 shows a fifth embodiment of the present invention.
2 is a configuration diagram of a vibration wave motor showing the embodiment of FIG.

A vibration wave motor as a vibration wave driving device is
When an AC electric field having a temporal phase difference of π / 2 is applied to the piezoelectric element c from a power source (not shown), two bending vibrations are excited in two directions orthogonal to each other. A circular motion is formed on the upper end surface of the disk-shaped elastic body d with which the rotor h is in contact, and the rotor h pressed by the disk-shaped elastic body d having wear resistance is frictionally driven. e is a shaft rod, and a screw f for clamping the vibrating body is
1, a motor fixing body g is provided on the upper part by a coupling screw f2. A contact spring h1 is joined to the rotor h by adhesion or the like, and a spring case h2 is fitted. i is an output gear, which is fitted and coupled to the spring case h2 so as not to move in the radial direction. j is a coil spring for pressurization. A joint portion k between the motor fixed body g and the gear i constitutes a sliding bearing. l is a flexible substrate for supplying power to the piezoelectric element.

In each of the above-described embodiments, as a means for providing a difference in dynamic rigidity in the vibration system of bending vibrations formed in the vibrating body in two directions orthogonal to each other, the vertical and horizontal dimensional ratios of the piezoelectric elements are changed. Then, it becomes easy to adjust the frequency difference between the both vibration systems.

[0028]

As described above, according to the first and second aspects of the present invention, it is possible to effectively utilize the relatively expensive electro-mechanical energy conversion element such as a piezoelectric element among the vibrating body components. You can retrieve the output. Further lower voltage can be achieved. As a result, a booster circuit and the like are not required, and the cost can be reduced, and an inexpensive vibration wave drive device such as a vibration wave motor can be provided.

According to the third aspect of the invention, since the sheet cut out can be used as it is, the piezoelectric element can be more effectively utilized.

According to the invention of claim 4, it is possible to provide a vibration wave motor capable of easily adjusting the resonance frequency difference and maintaining stable performance.

According to the fifth aspect of the invention, the diameter of the circumscribed circle of the electro-mechanical energy conversion element having a polygonal cross section and the diameter of the rod-shaped member having a circular cross section have the same length. Therefore, it can be easily assembled by matching the outer shapes.

[Brief description of drawings]

1A and 1B show a first embodiment of a vibrating body in a vibration wave driving device of the present invention, where FIG. 1A is a sectional view and FIG. 1B is a perspective view.

FIG. 2 is a second vibrating body in the vibration wave driving device of the present invention.
2A shows an embodiment of the present invention, in which (a) is a sectional view and (b) is a perspective view.

FIG. 3 is a third vibrating body in the vibration wave driving device of the present invention.
2A shows an embodiment of the present invention, in which (a) is a sectional view and (b) is a perspective view.

FIG. 4 is a view showing a method for manufacturing the piezoelectric element of FIG. 6 (c).

FIG. 5 is a sectional view showing a fifth embodiment of a vibration wave driving device of the present invention.

6A to 6C are cross-sectional views each showing the shape of a piezoelectric element incorporated in a vibrating body in the vibration wave driving device of the present invention.

7A and 7B are views showing vibration directions in the piezoelectric element of FIGS. 6C and 6A.

[Explanation of symbols]

a first elastic body b Second elastic body c Electric-mechanical energy conversion element (piezoelectric element) d disk-shaped elastic body e bolt f screw part g Motor fixed body h rotor I gear J coil spring K sliding bearing L flexible board

Continued front page    F term (reference) 5H680 AA01 AA19 BB02 BB11 BC01                       CC01 DD02 DD12 DD23 DD53                       DD65 DD74 DD85 EE04 EE12                       FF04 FF32

Claims (5)

[Claims] 1. An electro-mechanical energy conversion element having a polygonal cross section orthogonal to the axial direction, and a pair of metallic elastic bodies having a circular cross section orthogonal to the axial direction. Then, the electro-mechanical energy conversion element is arranged between the pair of metal elastic bodies, and the pair of metal elastic bodies are fastened by fastening means, so that the electricity- A vibration wave driving device comprising a rod-shaped vibrating body having a mechanical energy conversion element sandwiched and fixed. 2. The electro-mechanical energy conversion element,
The vibration wave driving device according to claim 1, wherein the vibrating body is configured to excite two bending vibrations whose vibration directions are orthogonal to each other. 3. The vibration wave driving device according to claim 1, wherein the electro-mechanical energy conversion element has a rectangular cross section. 4. A dynamic rigidity difference is provided in a vibration system in which the two bending vibrations are excited by changing a longitudinal / lateral dimension ratio of the electro-mechanical energy conversion element. 2. The vibration wave driving device according to 2 or 3. 5. The diameter of the circumscribed circle of the electro-mechanical energy conversion element and the diameter of the metal rod-shaped elastic body are the same.
The vibration wave driving device according to 2, 3, or 4.