JPS59110388A - Vibration wave motor - Google Patents

Abstract

PURPOSE:To obtain a vibration wave motor capable of normally and reversely rotating in a high drive efficiency by bonding a plurality of electrostrictive elements to an annular unit which increases in thickness toward radial direction, and frictionally driving a movable unit which is pressure contacted with the annular unit by applying a frequency voltage to the elements. CONSTITUTION:A vibration absorber 4, an annular metal vibrator 2 in which electrostrictive elements 3 are bonded to the absorber 4 side and a movable unit 1 are engaged in this order with a central cylinder 5a of a stationary unit 5 to become a base in such a manner that the unit 5, the absorber 4 and the vibrator 2 are mounted so as not to rotate to each other. The unit 1 is pressure contacted by its own weight or energizing means with the vibrator 2. The elements 3 are formed of two groups of a plurality of electrostrictive elements 3a, 3b, which are arranged at 1/2 pitch of the wavelength (lambda) of the vibration wave, and AC voltages are respectively applied via a power source 6a and a 90 deg. phase unit 6b. The vibrator 2 is plane at the element 3 side, and formed at the other to increase in thickness toward the radial direction, and the unit 1 having the raised curved surface which coincides with the annularly recessed curved surface is pressure contacted therewith.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the structure of a vibration wave motor driven by progressive vibration waves.

As disclosed in, for example, Japanese Unexamined Patent Application Publication No. 52-23192, a vibration wave motor converts vibrational motion generated when a frequency voltage is applied to an electrostrictive element into rotational motion or dimensional interlocking. Compared to conventional electromagnetic motors, electromagnetic motors do not require windings, so they have a simple and compact structure, can provide high torque even when rotating at low speeds, and have the advantage of having a small moment of inertia, so they have been attracting attention recently.

However, conventionally known vibration wave motors use standing vibration waves generated in a vibrating body to frictionally drive a moving body such as a rotor in one direction when converting vibratory motion into rotational motion. The vibrating body and the moving body come into frictional contact during the forward motion of vibration, and separate during the backward motion. Therefore, the vibrating body and the moving body have a structure in which they contact each other within a minute range,
In other words, the structure must be close to point or line contact, which results in poor friction drive efficiency.

Further, since the driving force acts in a fixed direction, the moving body moves in only one direction. In order to move in the opposite direction, it is necessary to mechanically switch the vibration direction using another vibrator. Therefore, in order to obtain a vibration wave motor capable of forward and reverse rotation, the device becomes complicated, and the cylindrical size and compactness of the structure, which are the characteristics of vibration wave motors, are halved.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to overcome these drawbacks of conventional vibration wave motors and to provide a vibration wave motor that has a very simple structure, has high drive efficiency, and is capable of forward and reverse rotation.

In order to achieve the above object, the present invention has a plurality of electrostrictive elements 3 arranged and bonded in a phase difference manner to an annular vibrating body 2 whose thickness increases from the center in the radial direction. The polarized electrostrictive element 3 is bonded to the electrostrictive element 3.
A vibration wave characterized by applying a frequency voltage to generate a progressive vibration wave in the vibrating body 2, and using the progressive vibration wave to frictionally drive a moving body l brought into pressure contact with the vibrating body 2. It's a motor.

FIG. 1 shows an embodiment of a vibration wave motor to which the present invention is applied, disassembled into each element.

Five types of annular vibrating bodies 2 and movable bodies 1 are fitted into the central cylindrical part 5a of the fixed body 5, which serves as a base, in this order, with the electrostrictive elements 3 attached to the vibration absorbing body 4 and the absorbing body 4 side. Body 5・
The absorber 4 and the vibrator 2 are each arranged so that they do not rotate relative to each other. The movable body 1 is pressed against the vibrating body 2 by its own weight or a biasing means (not shown) to maintain the integrity of the motor. The plurality of electrostrictive elements 3a are arranged at a pitch of 1/2 of the wavelength of the vibration wave, and the plurality of electrostrictive elements 3b are also arranged at a pitch of 1/2 of the wavelength of the vibration wave.
Arranged in pitch. Instead of arranging a plurality of electrostrictive elements 3, a single annular element 3 may be used as shown in FIG. 8, and it may be polarized at the pitch to form the polarized parts 3a and 3b. The mutual pitch between the electrostrictive elements 3a and 3b is (no+1/
4) A shifted phase difference arrangement (no=0, l, 2.3...) is performed. An absorber 4 is provided in each of the electrostrictive elements 3a.
A lead wire 11a is connected to the side thereof, and a lead wire 11b is connected to each of the electrostrictive elements 3b, each of which is connected to the electrode #i6a and the 80° phase shifter 6b (see FIG. 3).

Further, a lead wire 11c is connected to the metal vibrating body 2 and connected to an AC power source 6a. The annular vibrating body 2 has a flat surface on the electrostrictive element 3 side, and the other surface is formed so that the plate thickness becomes thicker toward the radial direction. This change in thickness forms a quadratic curve as shown in FIG. The friction portion 1a of the movable body 1 having a convex curved surface that matches this concave curved surface is pressed against the annular concave curved surface formed by this cross-sectional curve (see Fig. 2).
.

The friction portion 1a is made of hard rubber or the like to increase frictional force and reduce itching and wear. In addition, the absorber 4 is made of rubber.
It is made of felt or the like so that mechanical vibrations are not transmitted to the fixed body 5.

The operation of the vibration wave motor configured as described above is as follows.

FIG. 3 shows how vibration waves are generated in the motor.

Electrostrictive element-f-3a and 3b bonded to metal vibrating body 2
are shown adjacent to each other for convenience of explanation, but since they satisfy the above input/4 phase shift condition, they are substantially the same as the arrangement of the electrostrictive elements 3a and 3b of the motor shown in FIG. are equivalent.

2 in each of the E strain elements 3a and 3b indicates that the AC voltage expands when the cycle is on the positive side, and O indicates that it also decreases during the cycle on the positive side.

The metal vibrating body 2 is made to resemble one of the electrostrictive elements 3a and 3b, and the electrostrictive element 3a is supplied with V-V from an AC power source 6a. sin
An AC voltage of ωt is applied, and an AC voltage of V=V, )sin(ωt±π/2) with an input/4 phase shift is applied from the AC power supply 6a through the 900 phase shifter 6b to the electrostrictive element 3b. . The ten or minus in the equation is switched by the phase shifter 6b depending on the direction in which the moving body l (omitted in this figure) is moved, and +
When switched to the side, the +90° phase moves in the direction of non-slip, and -
When switched to the side, the phase shifts by 90 degrees and moves in the opposite direction. It is now switched to the - side, and the electrostrictive element 3b has V=Vos.
Assume that a voltage of i n (ωt-π/2) is applied. Only the electrostrictive element 3a alone has a voltage V=V(, sinωt
When the vibration occurs due to the vibration caused by the Anzai wave as shown in FIG.
=V□s i n (ωt −π/2), vibrations due to standing waves as shown in (b) occur.

The two out-of-phase alternating currents are simultaneously transmitted to each electrostrictive element 3.
When applied to a and 3b, the vibration wave becomes progressive. (A) is time t = 2nπ/ω, (B) is t = π/2ω + 2nπ
10n, (c) is L=π/ω+2nπ/ω, (d) is t
=3π/2ω+2nπ/ω, and the wavefront of the vibration wave travels in the X direction.

Such progressive vibration waves are accompanied by longitudinal waves and transverse waves, and if we focus on the mass point A of the vibrating body 2 as shown in Fig. It is moving in an elliptical motion. Since the moving body 1 is in pressure contact with the surface of the vibrating body 2 and comes into contact only with the apex of the vibrating surface, the component of the longitudinal amplitude U of the elliptical motion of the mass point A-A... at the apex The moving body l moves in the direction of arrow N.

By shifting the phase by +900 using a 900 phase shifter, the vibration wave becomes -
Moving in the X direction, the moving body 1 moves in the opposite direction to the N direction.

As described above, the vibration wave motor driven by progressive vibration waves can be switched between forward and reverse directions with an extremely simple configuration.

The velocity at the apex of the mass point A is V = 2πfu (f is the vibration frequency), and the moving velocity of the moving body l depends on this, and since it is frictionally driven by pressurized contact, the lateral vibration W It also depends on. That is, the moving speed of the moving body I is proportional to the magnitude of the elliptical motion of the mass point A, and the magnitude of the elliptical motion is proportional to the voltage applied to the electrostrictive element.

Since the frictional drive of the moving body 1 is performed at the apex of the wave surface of the progressive vibration wave of the vibrating body 2, the resonance of the wave surface in the direction of the apex (Z-axis direction in Figure 4) improves the driving efficiency. It is necessary to do so. Frequency of input voltage f (-2πω)
Assuming that the Young's modulus of the vibrating body 2 is E, the hardness, ρ, and the thickness h, and the wavelength of the wave created by this is f=, /Nゲ〇〈7・πh/〈2. ．． ．． ．． There is a relationship (1), and resonance will occur if the plate thickness satisfies this relationship.

Since the vibrating body 2 in the example is annular, equation (1) is valid within the range of a micro ring [1 J] in the diameter of the ring, and the circumference πD is n times the wavelength input (n is a natural number). resonates when

That is, input=πp/n, ,,,'(2).

Therefore, from equations (1) and (2), the relationship h=J3p/E·πfD2/n2, . . . (3) holds true.

In the embodiment shown in FIG. 2, the quadratic curve formed on the movable body l side of the cross section of the vibrating body 2 satisfies equation (3). ), the wavefront resonates and extremely powerful drive efficiency can be obtained.

FIG. 5 shows another embodiment of the annular vibrating body 2 and the movable body l, in which the electrostrictive element side of the vibrating body 2 is formed flat, and the thickness at the inner diameter D1 on the movable body 1 side is −6E. * πf D
(In 2/n 2, the thickness at the outer diameter D2 is h2 = r d ff EsπfD7'/n' and the thickness is connected by a straight line. In this case as well, D2 is Since it is sufficiently large compared to 7)*-πf/n2, substantially the entire surface of the vibrating body 2 resonates, and high driving efficiency can be obtained.

In addition, it is possible to drive the vibrating body 2 formed into an annular arc surface on the movable body l side with high efficiency similar to the above embodiment.

In the above embodiment, the electrostrictive element 3 side of the vibrating body 2 is made flat, but the above-mentioned curved or inclined surface may be provided on the electrostrictive element 3 side of the vibrating body 2, or on both sides. It may be something.

As an example, FIG. 6 shows an electrostrictive element 3 on the inclined surface of the vibrating body 2.
It shows what is glued together.

As described above, since the vibration wave motor of the present invention is driven by progressive vibration waves, it can easily be switched between forward and reverse directions, and furthermore, the vibration wave has a good resonance state, so that high driving efficiency can be obtained.

Figure 7 shows how the vibration wave motor of the present invention can be applied to various cameras such as still cameras, movie cameras, television cameras, and video cameras.
Various projectors such as movie projectors, enlargers, slide projectors, etc. and various Jl of light ffl /1lll constant a'i7;=
This example is applied as an aperture drive source for a lens in an optical device such as a fixed-frame machine.

The absorber 4, the electrostrictive element 3, the vibrating body 2, and the center hole of the rotating body 9, which is a moving body, are fitted in order into the central cylindrical portion 7a of the base 7, and the absorber 4, 'ilj: The strain element 3 and the vibrating body 2 are designed not to rotate. Circular hole 12b and arcuate hole 12a of aperture blade 12, protrusion 7b of base 7, and rotating body 9
The protrusions 9a are engaged with each other, and the thrust bearings 13 or spacers 14 are positioned above the protrusions 9a, and the retainer cylinders 15 are used to suppress the protrusions 9a. The base 7 and the restraining cylinder 15 are pressed by a screw 17 and connected by a screw 16 to maintain the integrity of the aperture unit. This aperture unit forms part of the lens frame.

Lead wires 11aellc and llb/llc to the electrostrictive element 3
When an alternating current with a phase shift of -90° is applied to each of the rotating body 9, the rotating body 9 rotates, and the aperture blade 12 engaged with the protrusion 9a rotates forward along the arcuate hole 12a about the axis 7b'-12b. . Since the aperture blades 12 are provided on each of the plurality of protrusions 9a, when the aperture blades 12 are rotated forward, they narrow down the central cavity. When the phase of the alternating current is shifted by +90° in the opposite direction to the above, the rotating body 9 rotates in the opposite direction and the aperture is heard. In addition, SW in the same figure
is in contact with the protrusion 9b of the rotating body 9 and the aperture when it is opened, and is turned on.
The off switch 8a is a comb-shaped electrode that slides into contact with an electrode 8b attached to the rotating body 9 and outputs a signal corresponding to the aperture blade aperture position, both of which are necessary for aperture control.

FIG. 1 is an exploded perspective view of a vibration wave motor to which the present invention is applied;
Fig. 2 is a partially cutaway side view of the vibration wave motor, Figs. 3 and 4 are diagrams explaining the driving principle of the vibration wave motor, and Figs. 5 and 6 are partially cutaway side views of another embodiment. 7 is a perspective view of an embodiment in which the vibration wave motor of the present invention is applied to an aperture drive source, and FIG. 8 is a plan view of another embodiment of an electrostrictive element.

1 is a moving body, 2 is a vibrating body, 3 is an electrostrictive element, 4 is a vibration absorber, and 5 is a fixed body.

Figure 3 (20 □
Figure 1 Figure 7 Figure 2 Figure 6

Claims (1)

[Claims] (1) An annular vibrating body whose thickness increases in the radial direction from the center, a plurality of electrostrictive elements arranged and bonded with a phase difference, and an electrostrictive element polarized with a phase difference of 1 or more. The elements are joined, and a frequency voltage is applied to the electrostrictive element to generate a progressive vibration wave in the vibrating body, and the progressive vibration wave frictionally drives a moving body that is brought into pressure contact with the vibrating body. A vibration wave motor characterized by: