JPH02228266A - Ultrasonic vibrator and ultrasonic motor - Google Patents

Abstract

PURPOSE:To improve the degree of freedom of construction requirements for an elastic body and an exciting body and enable operation with a high efficiency and large output by making one phase to bidirectional vibration the same phase, making the other an opposite phase, and preventing said elastic body from vibrating unnecessarily. CONSTITUTION:When alternating voltage of frequency (f) is applied to a first piezoelectric body 12 to vibrate, a plate elastic body 16 resonates in a longitudinal vibration primary mode and point A extends in the direction of +x. In this time, the plate elastic body 16 resonates also in a bending vibration secondary mode and, in this mode, point A moves in the direction of +y. When voltage of frequency (f) having the same phase as the alternating voltage applied to the first piezoelectric body 12 is applied to a second piezoelectric body 13 to vibrate, the plate elastic body 16 resonates in the longitudinal vibration primary mode and point A extends in the direction of +x. In this time, the plate elastic body 16 resonates also, in the binding vibration secondary mode and, in this mode, point A moves in the direction of -y. Thereby no amplitude appears in the direction of (y). When the voltage has an opposite phase, no amplitude appears in the direction of (x).

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an ultrasonic vibrator that is excited with approximately elliptical vibration, and an ultrasonic motor that utilizes the vibrator.

[Prior Art] Conventionally, the above-mentioned ultrasonic transducers have been mainly used in standing wave type ultrasonic motors.

The operating principle of a standing wave type ultrasonic motor is that a moving element is brought into contact with a predetermined pressure against an ultrasonic vibrator that is excited in approximately elliptical motion, and the friction force between each mass point moving approximately in an elliptical manner and the moving element is used. It drives the mover.

Since the standing wave type ultrasonic vibrator can easily be configured to achieve highly efficient vibration, the standing wave type motor has the advantage of higher efficiency and larger output than the traveling wave type motor.

The ultrasonic vibrator used in conventional standing wave motors generates unidirectional vibration at the contact surface between the elastic body and the exciting body in order to excite approximately elliptical motion with high efficiency. At the contact surface between the rotor and the mover, approximately elliptical motion is obtained by using a mechanical resonance system having a natural vibration mode that performs elliptical vibration.

[Problems to be Solved by the Invention] However, when attempting to excite unidirectional vibrations in an elastic body that vibrates in two directions at the same frequency, it is difficult to overcome the effects of slight asymmetry in the structure of the elastic body or the exciting body. It was difficult to not excite vibrations in the other direction at all.

Therefore, there is a drawback that vibration is hindered by the unnecessary vibration, and a vibrator with high efficiency and high output cannot be obtained.

Furthermore, since only a single vibration is excited in the elastic body, there is a drawback that the configuration of the vibrator is severely limited.

The present invention has been made to solve the above-mentioned problems, and its purpose is to increase the degree of freedom in the configuration of the elastic body and the exciting body by creating a configuration that does not generate unnecessary vibrations in the elastic body. The object of the present invention is to provide an ultrasonic transducer that is large, highly efficient, and capable of high output operation.

[Means for Solving the Problems] In order to achieve the above object, the ultrasonic transducer of the present invention includes an elastic body that resonates at approximately the same frequency in the first and second directions;
a first excitation body that excites vibrations of the substantially same frequency in both directions of the elastic body; and a second excitation body that excites opposite vibrations in a second direction.

Further, the ultrasonic motor of the present invention includes the ultrasonic transducer described above and a movable element in contact with the elastic body of the ultrasonic transducer.

[Function] In the ultrasonic transducer of the present invention having the above configuration,
The first excitation body applies vibrations to the elastic body in two different directions.

At the same time, the second excitation body applies vibration to the elastic body in the same vibration direction as the two-way vibration.

At this time, the phase relationship for the two-way vibration is such that one side is in phase and the other side is out of phase. Therefore, the energy of each vibration is effectively used without being consumed as unnecessary vibrations.

By adjusting the vibration phases of the two excitation bodies, substantially elliptical vibration of an arbitrary shape can be obtained in the elastic body.

Further, in the ultrasonic motor of the present invention having the above-mentioned configuration, a driving force is generated in the movable element by the vibration of the ultrasonic vibrator.

[Example] Hereinafter, an example embodying the present invention will be described with reference to the drawings.

1 to 3 show the ultrasonic transducer of this embodiment.

In the ultrasonic transducer 11 of this embodiment, a first piezoelectric body 12 and a second piezoelectric body 13 are fixed to a stand 15 at symmetrical positions with a bolt 14 as the center. The first piezoelectric body 12 and the 'N52 piezoelectric body 13 are polarized in the vertical direction in FIG. 1 and vibrate in the thickness direction. On the upper surfaces of the first piezoelectric body 12 and the second piezoelectric body 13, a plate-shaped elastic body 16 is fixed to the stand 15 by the bolts 14.

Electrodes 17 and 18 are installed on the lower surfaces of the first piezoelectric body 12 and the second piezoelectric body 13. Further, the plate-like elastic body 16 also serves as an electrode for the piezoelectric bodies 12 and 13.

Furthermore, this plate-shaped elastic body 16 bends and vibrates at a predetermined frequency f in its thickness direction. Further, they longitudinally vibrate in the length direction at approximately the same frequency f.

Generally, the resonant frequency of longitudinal vibration propagating in an elastic plate depends on the length of the elastic plate. Further, the resonant frequency of bending vibration in the thickness direction of the plate-like elastic body depends on the length and thickness. Therefore, it is easy to design the plate-like elastic body 16 as described above.

The operation of the vibrator configured as described above will be explained below with reference to FIG.

First, when an AC voltage of frequency f is applied to the first piezoelectric body 12 to cause it to vibrate, the plate-like elastic body 16 resonates in the first-order mode of longitudinal vibration, and point A in the figure extends in the +X direction. At this time, the plate-like elastic body 16 also resonates in the second-order mode of bending vibration, and point A in the figure moves in the +y force direction.

Next, the first piezoelectric body 12 is applied to the second piezoelectric body 13 at a frequency f.
When a voltage in phase with the AC voltage applied to is applied to vibrate, the plate-shaped elastic body 16 resonates in the first mode of longitudinal vibration, and point A in the figure extends in the +X direction.

At this time, the plate-like elastic body 16 also resonates in the second-order bending vibration, and the point A in the figure moves in the -y force direction.

That is, when the first piezoelectric body 12 and the second piezoelectric body 13 are vibrated simultaneously, when the voltages applied to both piezoelectric bodies are in the same phase, the bending vibration is completely canceled and no amplitude appears in the y direction. Furthermore, when the voltages applied to both piezoelectric bodies are of opposite phase, the longitudinal vibration is completely canceled out, and the
No amplitude appears in the direction.

In this way, by adjusting the phase of the voltage applied to the two piezoelectric bodies 12 and 13, the end portion A of the plate-like elastic body 16 can be adjusted.
It is possible to generate approximately elliptical vibration of any shape at a point.

In the ultrasonic vibrator 11 as described above, in order to efficiently transmit the vibrations generated by the two piezoelectric bodies 12 and 13 to the plate-like elastic body 16, there is a gap between the piezoelectric bodies 12 and 13 and the plate-like elastic body 16. A connector 21 on which a plurality of inclined pieces are formed.
It is also possible to sandwich 22 and 22. The vibration direction of the thickness vibration generated in the piezoelectric bodies 12 and 13 is changed by the coupler, and longitudinal vibration is efficiently generated in the plate-shaped elastic body 16.

Next, the configuration of a linear ultrasonic motor that suitably utilizes the ultrasonic transducer 11 as described above will be explained based on FIG. 5. In this figure, each member given the same reference numeral as in FIGS. 1 to 4 means the same as each component described in detail above.

In the linear ultrasonic motor 31, the ultrasonic transducer 11 is fixed to a yoke 32, and an output section 33 is formed at the end of the plate-shaped elastic body 16 of the ultrasonic transducer 11.

A movable element 34 is crimped to the output portion 33 by a leaf spring 35, and one end of the leaf spring is fixed to the yoke 32.

In the linear ultrasonic motor 31 configured as described above, when the ultrasonic vibrator 11 is excited, the movable element 34 receives a driving force due to approximately elliptical penetration of the plate-like elastic body 16,
It moves in the direction of arrow B in the figure.

This driving force is generated by the frictional force between the plate-shaped elastic body 16 and the movable element 34.

Although the above embodiment uses a piezoelectric material as the driving element of the vibrator, it is not limited to this, and other elements capable of converting electrical energy into mechanical energy, such as an electrostrictive element or a magnetostrictive element, may be used. Good too. In addition, in the embodiment, an example was explained in which the shape of the ultrasonic transducer is a flat plate, but if vibration is excited in the length direction and bending vibration is excited in the axial direction, and approximately elliptical motion is generated, the shape is a flat plate. It is not limited to. In addition, various modifications can be made without departing from the spirit of the present invention.

[Effects of the Invention] As is clear from the detailed description above, according to the present invention, unnecessary vibrations are not generated in the elastic body, so there is a large degree of freedom in the configuration conditions of the elastic body and the exciting body, and high efficiency and large An ultrasonic transducer capable of output operation can be provided.

By appropriately utilizing the ultrasonic vibrator, it is possible to provide an ultrasonic motor that has characteristics of high efficiency and large output, and can easily control a substantially elliptical motion locus.

[Brief explanation of the drawing]

1 to 5 show embodiments embodying the present invention. FIG. 1 is a side view of an ultrasonic transducer to which the present invention is applied, and FIG. 2 is an exploded view of the ultrasonic transducer. A perspective view, FIG. 3 is a diagram showing a comparison of the excitation position and amplitude in an ultrasonic vibrator, FIG. 4 is an exploded perspective view of an ultrasonic vibrator as another embodiment, and FIG. 5 is a diagram showing the above-mentioned ultrasonic vibration. FIG. 2 is a side view of a linear ultrasonic motor to which a child is applied. In the figure, 12 is a first piezoelectric element corresponding to the first exciter, 13
14 is a bolt corresponding to the holding part; 16 is a plate-shaped elastic body corresponding to the elastic body;
21 and 22 are connectors, and 34 is a mover.

Claims (5)

[Claims] 1. an elastic body that resonates at substantially the same frequency in a first direction and a second direction substantially orthogonal to the first direction, and simultaneously exciting vibrations at the frequency in both the first direction and the second direction of the elastic body; Vibration of the frequency is simultaneously excited in both the first direction and the second direction of the first exciting body and the elastic body, and the phase relationship of both vibrations is opposite to that of the first exciting body. An ultrasonic transducer comprising a second excitation body. 2. 2. The ultrasonic transducer according to claim 1, wherein the two-way vibration has at least one coinciding node, and the ultrasonic vibrator has a holding part that holds the overlapping nodes. Sound wave vibrator. 3. The ultrasonic vibrator according to claim 1 or 2, further comprising a connector for converting a vibration direction between the elastic body and at least one of the respective excitation bodies, and the plate-like elastic body of the connector. An ultrasonic transducer characterized in that a plurality of inclined pieces are formed on the contact surface with the ultrasonic transducer. 4. The ultrasonic transducer according to claim 2 or 3, wherein at least bending vibration and longitudinal vibration are excited in the elastic body, and the first excitation body and the second excitation body are arranged on the same surface of the plate-like elastic body. An ultrasonic vibrator characterized in that the ultrasonic vibrator is installed at an antinode position that is in the opposite phase of the bending vibration. 5. An ultrasonic motor comprising a movable element in contact with the ultrasonic vibrator according to any one of claims 1 to 4.