JP2001037264A - Oscillatory wave driver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress changes in a plurality of natural frequencies for stable driving by taking a plurality of points of an oscillating body as contact points, and setting the direction of oscillation generated by the standing wave of the contact point to the direction different from the one working on a contact body. SOLUTION: A piezoelectric element (b) serving as an electric to mechanical energy transducer is bonded to the underside of an oscillating body (a) formed out of metal, and a supporting pin (p) is inserted into an insertion hole a1 in the oscillating body (a) to support it. The surface of the oscillating body (a) formed with contact points c1, c2 constituted of protruding portions, and is formed into an arc-shaped cross-section shape so as to permit easy contact with a cylindrical body (n) having an axis (o) as a contact body. An AC magnetic field by two-phase alternating signal is applied to two electrode regions of the piezoelectric element (b) to perform two oscillatory excitation, or excitation of a combination of oscillations at a first mode and a second mode, so that the contact points c1, c2 are subjected to circular or elliptic movement in the same direction. It is thus possible to provide a uniaxial rotating acoustic motor easily.

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 for obtaining a driving force by a vibration wave such as an ultrasonic wave.

[0002]

2. Description of the Related Art As an ultrasonic linear motor as a conventional vibration wave driving device, for example, as disclosed in Japanese Patent Application Laid-Open No. H7-177767, a vibration body is made to generate a combined vibration that combines longitudinal vibration and bending vibration. There is known a device in which an elliptical motion is excited at a contact point of a vibrating body with a driven body, and a contact body pressed and contacted here is driven by a frictional force.

[0003]

In the vibrating body used in this type of ultrasonic linear motor, at the contact point, the vibration direction of the contact point due to longitudinal vibration is parallel to (same direction as) the movement direction of the driven body. The direction of vibration of the contact point due to bending vibration is perpendicular to the direction of motion of the driven body.

[0004] The direction of application of the pressing force of the contact body to the vibrating body is perpendicular to the longitudinal vibration direction and parallel (same direction) to the bending vibration.

By the way, these two directions of vibration are both driven at the resonance frequency or a frequency near the resonance frequency,
In order to obtain an elliptical motion in which the vibration displacement is enlarged, the two natural frequencies must be almost the same.

[0006] The natural frequency of the vibrating body changes depending on the magnitude or direction of the force acting on the vibrating body. Therefore, even if the two natural frequencies match in the vibrating body alone, the amount of change in the two natural frequencies differs depending on the pressing force and load. Sometimes it was not possible.

[0007]

In order to solve the above-mentioned problem, it is sufficient that the change in the natural frequency due to the acting force or the load is approximately equal.

Considering the best practice, if both vibration displacements of the vibrating body at the contact point with the contact body are approximately 45 degrees with respect to the acting direction of the pressing force, the influence of the pressing force on the natural frequency is considered. Can be made substantially equal.

[0009] Also, with respect to the motor load, by setting the vibration displacement of both vibrations of the vibrating body to approximately 45 degrees with respect to the action direction of the load, that is, the direction of relative movement with the contact body, both vibrations of the load are achieved. Can have substantially the same effect on the natural frequency.

At this time, the amount of change in the natural frequency with respect to these forces is substantially equal in both vibration modes. If the natural frequencies of the vibrating body are matched, stable motor drive can be performed.

[0011] Even if the angle is not 45 degrees, if the vibration direction does not coincide with the pressing force or the load, the difference between the natural frequency change amounts of the two vibrations can be made smaller than in the past, and the motor performance can be reduced. Be improved.

According to a first aspect of the present invention, a plurality of standing waves are excited in a vibrating body to generate a circular or elliptical motion in the same direction at a plurality of places, and a pressure contact is made with the plurality of places of the vibrating body as contact points. A vibration wave driving device that performs relative motion of a contacting body, wherein the direction of vibration generated by each standing wave at the contact point is set to a direction different from the direction of the pressing force acting on the contact point. It is characterized by a vibration wave driving device.

According to a second aspect of the present invention, a plurality of standing waves are excited in a vibrating body to generate a circular or elliptical motion in the same direction at a plurality of places, and a pressure contact is made with the plurality of places of the vibrating body as contact points. A vibration wave driving device that performs relative motion of a contacting body, wherein the direction of vibration generated by each standing wave at a contact point is set to a direction different from the direction of the relative motion. And

According to a third aspect of the present invention, there is further provided an electro-mechanical energy conversion element having a plurality of regions joined to the vibrating body, and the plurality of standing waves are provided in a plurality of types in a plurality of regions of the conversion element. It features a vibration wave driving device generated by a combination of vibrations.

According to a fourth aspect of the present invention, there is provided the vibration wave driving device wherein the direction of the vibration generated by the plurality of standing waves is set to approximately 45 degrees with respect to the direction of the pressing force.

According to a fifth aspect of the present invention, the vibration wave driving device is further characterized in that the direction of the vibration generated by the plurality of standing waves is set to approximately 45 degrees with respect to the direction of the relative motion.

The invention according to claim 6 is further characterized in that the plurality of standing waves are generated by vibration in a bending vibration mode.

[0018]

FIG. 1 is a perspective view of a vibrating body according to a first embodiment of the present invention.

A is a vibrator made of metal such as brass. b is a piezoelectric element as an electromechanical energy conversion element,
It is bonded to the lower surface of the vibrating body a.

A1 is a hole for inserting a pin for supporting the vibrating body a.

FIGS. 2A and 2B show natural vibration modes when the vibrating body a vibrates. (A) and (b) are bending vibrations and have substantially the same natural frequency.

Reference numerals c1 and c2 denote contact points with a moving body as a contact body, and are provided with small projections (not shown) made of a wear-resistant member.

The arrow in the drawing indicates the direction of the vibration displacement, and in both longitudinal modes in the vertical cross section with respect to the upper surface of the vibrating body, both directions point at approximately 45 degrees at the contact points c1 and c2.

AC electric fields ma and m as two-phase alternating signals
b is applied to the two electrode regions of the piezoelectric element b specifically shown in FIG. 4, thereby exciting two vibrations, that is, combining the first mode and the second mode vibration as shown in FIG. By the excitation, the contact points c1 and c2 make a circular or elliptical motion in the same direction.

When the moving body is pressed against the contact points c1 and c2 of the vibrating body a, the moving body is linearly driven by the frictional force. In this case, the vibrating body a is fixed, but the vibrating body a can be driven linearly by fixing the contact body.

FIG. 3 is a structural view of a linear ultrasonic motor using the vibrating body according to the present embodiment.

A felt c as a vibration absorbing member is disposed on the bottom surface of the piezoelectric element b.
The three members are in an adhesive relationship so as to sandwich the felt c between them. The pedestal d is positioned by a projection provided on the bottom surface and fixed to the fixed base e.

A fixed base e is provided with four guide rods f at equal intervals, and a movable body l is a vibrating body by a nut j, a pressing plate i, a coil spring h, a direct-acting bearing structure, and a steel ball g. Pressurized to a. The pressing force is the z direction in the figure, the moving direction of the moving body 1 (the direction of load) is the x direction in the figure, and the contact point c of the vibrating body is
The vibration direction generated in 1 and c2 is approximately 45 degrees in both the pressing force direction and the moving direction.

FIG. 4 shows the arrangement of electrodes (arrangement of polarization regions) provided on the piezoelectric element b and the direction of polarization. The piezoelectric element b is polarized in the thickness direction, and the electrode region is provided in the same region as the two polarization regions. The electrode region (polarization region) is divided in the same direction as the direction in which the groove a2 provided on the vibrating body a extends, and the polarization direction is reversed at the boundary. The back surface (not shown) is bonded to the vibrating body a by a full-surface electrode.

Ma and mb are signal lines (wirings) for supplying power to the piezoelectric element b, and apply an AC electric field to both electrodes with the back surface being ground. In this embodiment, the vibrating body a is used as the conductive material. However, depending on the material of the vibrating body a, it is necessary to connect a dedicated signal line (wiring) also to the back surface of the piezoelectric element b.

In FIG. 3, a hole a1 of the vibrating body a is shown.
Is not used for support, but it is also possible to insert a support pin into the hole a1 to support at the position of the hole a1.

(Second Embodiment) FIG. 6 shows an apparatus for rotating a cylindrical body as a contact body by a vibrating body a1 '.

N is a cylinder serving as a moving body, and o is a cylinder axis. p is a vibrating body supporting pin inserted into the hole a1.

Surface a of contacting side of vibrating body a1 'with cylindrical body n
Numeral 4 has an arc-shaped cross-sectional shape so as to easily come into contact with the cylindrical body a4. Note that the two contact points c1,
c2 forms a protrusion.

With such a configuration, a uniaxial rotary ultrasonic motor can be easily realized.

(Third Embodiment) FIG. 7 shows an apparatus for rotating a sphere q as a moving body around one axis by using a plurality of vibrating bodies a'-1 and a'-2.

As described above, the output torque or thrust can be easily increased by using a plurality of vibrators according to the present embodiment.

(Fourth Embodiment) FIG. 8 shows that two vibrators a'-1 and a'-2 are arranged in a direction orthogonal to each other.
The sphere q can be rotated around two axes (in this example, around the y-axis and the z-axis).

The ball q is formed of a magnetic material, and the vibrators a'-1 and a'-2 themselves are used as magnets to increase the contact pressure by adsorption by an electromagnet, or conversely, pressurization utilizing magnetic repulsion is used. By such a device, it is possible to secure a contact pressure between the vibrating body and the ball q as the moving body, and to obtain a rotational force of the ball q in an arbitrary direction.

If three vibrators are used, movement control around three axes is possible, and application to robot joints and the like can be expected.

[0041]

In the vibration wave driving device constructed as described above, the direction of vibration at a plurality of contact points generated by a plurality of standing waves of the vibrating body is determined by the direction of the pressing force acting on the contact points. Alternatively, since the direction of movement is different from the direction of relative movement with respect to the contact member, a change in the natural frequency of the plurality of vibrations can be suppressed, and stable driving can be obtained as compared with the conventional one.

Further, if the direction of vibration at the plurality of contact points is set to be approximately 45 degrees with respect to the direction of the pressing force acting on the contact points or the direction of relative movement with the contact member, the plurality of vibrations caused by the pressing force or load can be obtained. Can have substantially the same effect on the natural frequency, and the driving performance can be greatly improved.

Further, by using the bending vibration as the vibration mode, the direction of the vibration generated by the plurality of standing waves of the vibrating body can be changed in the direction of the pressing force acting on the contact point or the direction of the relative movement with the contact member. Can be easily performed at a low voltage.

[Brief description of the drawings]

FIG. 1 is a perspective view of a vibrating body used in a first embodiment.

FIG. 2 is a diagram showing natural vibration modes in two vibrations of the vibrating body shown in FIG.

FIG. 3 is a sectional view of the vibration wave driving device according to the first embodiment.

FIG. 4 is an electrode and polarization pattern diagram of a piezoelectric element.

FIG. 5 is a diagram illustrating two vibration modes of a piezoelectric element.

FIG. 6 is a perspective view of a vibration wave driving device according to a second embodiment.

FIG. 7 is a perspective view of a vibration wave driving device according to a third embodiment.

FIG. 8 is a perspective view of a vibration wave driving device according to a fourth embodiment.

[Explanation of symbols]

 a Vibration body a 'Vibration body c1 Contact point c2 Contact point b Piezoelectric element l Moving body

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Takayuki Tsukimoto 3-30-2 Shimomaruko, Ota-ku, Tokyo F-term in Canon Inc. (reference) 5H680 AA06 AA10 BB13 BB15 CC02 CC06 DD01 DD15 DD23 DD27 DD53 DD63 DD65 DD67 DD74 DD92 EE10 FF08 FF26 FF33 FF36 GG24 GG31

Claims (6)

[Claims] 1. A contact in which a plurality of standing waves are excited in a vibrating body to generate circular or elliptical motion in the same direction at a plurality of locations, and the plurality of locations of the vibrating body are in pressure contact with the plurality of locations as contact points. A vibration wave driving device that performs relative motion of the body, the direction of vibration generated by each standing wave at the contact point,
The vibration wave driving device is set in a direction different from a direction of the pressing force acting on the contact point. 2. A contact in which a plurality of standing waves are excited in a vibrating body to generate circular or elliptical motion in the same direction at a plurality of locations, and the plurality of locations of the vibrating body are in pressure contact with the plurality of locations as contact points. A vibration wave driving device that performs relative motion of the body, the direction of vibration generated by each standing wave at the contact point,
A vibration wave driving device, wherein the direction is set to a direction different from the direction of the relative motion. 3. An electro-mechanical energy conversion device having a plurality of regions is joined to the vibrator, and the plurality of standing waves are generated by a combination of a plurality of types of vibrations in a plurality of regions of the conversion device. The vibration wave driving device according to claim 1 or 2, wherein: 4. The vibration wave drive according to claim 1, wherein the direction of the vibration generated by the plurality of standing waves is set to approximately 45 degrees with respect to the direction of the pressing force. apparatus. 5. The vibration wave drive according to claim 1, wherein the direction of the vibration generated by the plurality of standing waves is set to approximately 45 degrees with respect to the direction of the relative motion. apparatus. 6. The method according to claim 1, wherein the plurality of standing waves are generated by vibration in a bending vibration mode.
The vibration wave driving device according to any one of the above.