JP2760297B2 - Ultrasonic motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic
It relates to a sound wave motor. [0002] 2. Description of the Related Art A drive signal is transmitted to an electromechanical energy conversion element.
Signal, ultrasonic vibration is generated in the vibrating body,
The moving body pressed against the vibrating body moves due to the vibration of the vibrating body.
Ultrasonic motors that move to obtain a driving force are known. [0003] However, the vibrating body
The vibration of the moving object also causes the vibration of the moving object.
When the vibration of the moving body is transmitted to the driven member and noise is generated
There was a problem. Therefore, store the ultrasonic motor
If the housing is configured to support the driven member,
Vibration is transmitted to the housing, and the housing resonates and generates noise.
That phenomenon was easy to occur. Therefore, the present invention solves the above-mentioned problems and solves the noise.
Provide ultrasonic motor that can suppress sound and vibration
The porpose is to do. [0005] SUMMARY OF THE INVENTION An annularly formed elastic member is provided.
A body and an electromechanical transducer installed on the elastic body,
According to a drive signal applied to the electromechanical transducer,
An oscillator for generating a traveling wave traveling in a circumferential direction of the elastic body;
The traveling wave generates a traveling wave traveling in the same direction as the traveling wave.
A relative motion section that generates and performs relative motion with the vibrator
And a driven member that moves integrally with the relative motion member
And vibration caused by the traveling wave generated in the relative motion member.
The relative movement member so as not to be transmitted to the driven member.
And a buffer member disposed between the driven member and the driven member.
A wave motor was constructed. Further, the oscillator and the relative movement
A housing for accommodating the moving member;
The moving member may be configured to be movably supported. [0006] FIG. 1A shows an ultrasonic module according to an embodiment of the present invention.
1B is a sectional view of the ultrasonic motor.
FIG. 2 is a cross-sectional view when the ultrasonic motor is unitized.
FIGS. 3A and 3B show the rotation of the ultrasonic motor.
FIG. 4 is a structural diagram showing the shape of the trochanter, and FIG.
FIG. 5 is an explanatory view showing the principle of operation, and FIG.
It is a graph which shows the characteristic curve of a wave number and amplitude. As shown in FIGS. 1A and 1B,
The stator S as a vibrator is provided as an electromechanical transducer.
The piezoelectric element 2 and the traveling wave (surface
And an elastic body 1 that generates waves. On this stator S,
Ring-shaped rotation as a relative motion member pressed against the elastic body 1
The stator 3 and the ring-shaped rotor 3
, An ultrasonic motor is configured. This ring-shaped rotor
Numeral 3 denotes an annular ring having a constant width, the center O 'of which is the stator S
This ring is provided so as to be eccentric with respect to the center O of the ring.
Rotor 3 is rotated about the center O of the stator S as the center of rotation.
It is arranged to be. At this time, this ring-shaped rotation
The child 3 rotates on the fixed stator S, but the stator S
With an arbitrary amount of eccentricity δ. this
So that the center of the rotor 3 and the center of the stator S are eccentric.
When the rotor 3 is rotated, the sectional view shown in FIG.
Of the stator S and the rotor 3 on the surface 1a of the stator S.
The contact portion 1b moves with respect to the rotation center O with the rotation of the rotor 3.
As a result, a simple oscillation occurs with a single amplitude of the eccentricity δ, that is,
That is, the friction of the rotor 3 on the surface 1a of the stator S
The frictional contact surface is radially moved on the surface 1a by the rotation of the rotor 3.
To the stator S every moment.
The contact surface has changed. Therefore, as before
In addition, the contact surface between the rotor 3 and the stator S is
Unlike the rubbing contact, the surface 1a of the stator 3
Since the contact surface of the rotor 3 moves every moment, the stator S
Of the stator S
The entire surface 1a can be used efficiently
I have. The amount of eccentricity δ is within a range satisfying the following condition.
Arbitrarily determined. The condition is that the rotor 3 rotates eccentrically.
The ring of the rotor 3 always on the surface of the stator S
That is, it is set so as to rotate without protruding. here
The outer diameter of the stator S is D, the inner diameter is d, and the outer diameter of the rotor 3 is
The diameter is D ', the inner diameter is d', the ring width of the stator S is a,
Assuming that the ring width of the ring-shaped rotor 3 is b,
Is [0009] (Equation 1) The amount of eccentricity δ is set as follows. Figure 2
FIG. 2 is a structural diagram in which the ultrasonic motor of FIG. 1 is configured as a unit.
You. The ultrasonic motor is housed in the cylindrical cases 10a and 10b.
And a biasing means (for example,
An elastic member such as rubber) 6 on the urging means.
The disk 5 for uniformly transmitting the urging force of the disk 6
For absorbing vibration of stator S of ultrasonic motor
A cushioning material 4a is fixed, and an ultrasonic wave is placed on the protective cushioning material 4a.
A motor stator S is provided. The center of this stator S
Is arranged so as to coincide with the centers of the cases 10a and 10b.
Have been. On the inner diameter side of the stator S, a case 10a
Vibration of the ultrasonic motor is fixed to the inner cylinder of the case 10
has a support portion 7 configured to prevent propagation to
You. This support portion 7 protrudes from the inside of the stator S, as shown in FIG.
As shown in FIG.
And positions the stator 3 with respect to the case 10a.
And fixedly supported, and integrated with the stator S
It may be formed or formed by another member. On the stator S, the center is shifted by the amount of eccentricity δ.
A rotor 3 having a center is provided, and the
A cushioning material 4b for absorbing the movement is further placed on the cushioning material 4b.
A fixing member 8 is fixedly provided. The ring member 8 is a rotor
Through the ball race 9 to make the rotation of 3 smooth
And is disposed in the case 10b. This ring member 8
Is the center of rotation of the cases 10a and 10b
Thus, a guide groove provided concentrically with the center of the case 10b.
With the center of the case 10b in the guide groove.
The ball race 9 that is arranged in
Has been established. That is, the shape of the ring member 8 is
The side fixed to the element 3 is eccentric, and the
An eccentric ring whose contact side matches the center of the stator S
ing. Therefore, this unitized ultrasonic mode
To remove power from the motor,
The power of the ring member 8 to be used for equipment that uses this unit
The unit may be removed as appropriate, for example,
If you use it for Mera's shooting lens barrel, you can drive the aperture blade and lens
It can be used for driving and the like. The above is a rotation as one embodiment of the present invention.
When the center of the stator 3 is eccentric with respect to the center of the stator S
3A and FIG.
The ring-shaped rotor shown in FIG. FIG. 3 (A)
As shown in the figure, the ring-shaped rotor 31 has an outer diameter and an inner diameter.
It may be configured in a ring shape with the center eccentric. Also figure
As shown in FIG. 3 (B), the ring-shaped rotor 32 has an elliptical shape.
You may comprise in a shape. FIG. 4 shows the principle of operation of the stator S and the rotor 3.
As shown, the stator S is flexurally vibrated by the piezoelectric element 2.
And a traveling wave is generated on the surface. At this time, the stator
The traveling wave of S travels in the direction of arrow P, and the particle P1 on the surface is elliptical.
They are doing circular motion. The rotor 3 was pressed against this stator S
In this case, the rotor 3 generates a surface wave by the stator S,
The traveling direction is the arrow Q direction, and the particles Q1 on the surface are the same.
Perform elliptical motion in the same way. Here, the stator S and the rotor 3
The amplitude of vibration that generates surface waves depending on the material and shape
Is changed, and the amplitude of the stator and the rotor is changed in the following three cases.
Think about it. First, the amplitude A of the stator S_SIs the rotor 3
Amplitude A_ThreeIf it is larger, that is, the stator in the state of FIG.
The contact between the rotor S and the rotor 3 is determined by the wave crest of the stator S and the rotor 3
It becomes a valley of waves. In this case, the stator S and the rotor 3
Motion of the particles P1 and Q1 at the contact point
In the opposite direction, and the driving force of the ultrasonic motor increases.
You. Second, the amplitude A of the stator S_SAnd rotor 3
Amplitude A_ThreeAre equal, the stator S and the rotor 3
Will come into contact with each other. In this case, the stator S
Since the motion of the particles is opposite between the peak and the valley, the driving force is
They will cancel each other out. Third, the amplitude A of the stator S_STimes
Amplitude A of trochanter 3_ThreeIf smaller, the stator S and rotor
3 comes into contact with the valley of the wave of the stator S and the ridge of the wave of the rotor 3
become. In this case, the contact point between the stator S and the rotor 3
The movement of each particle P1 and Q1 is in the opposite direction
And the driving force of the ultrasonic motor increases,
The direction is opposite to the moving direction. A case where vibration isolation between the stator S and the rotor 3 is considered
Rotor 3 must transmit its rotation to an external mechanism
Therefore, it is more difficult to perform vibration isolation than the stator S.
Therefore, the first case where the driving force becomes large and the third case
Considering which one to choose, the vibration of rotor 3
Width A_ThreeIs the amplitude A of the stator S_SFirst case to be smaller
Would be better. Therefore, the amplitude A of the rotor 3
_ThreeIs the amplitude A of the stator S_SHere's how to make it smaller
You. FIG. 5 shows the resonance frequency of the stator S as f_S, Times
Let the resonance frequency of the trochanter 3 be f_ThreeThen, each frequency
And the relationship between amplitude and amplitude. However, at the resonance point
It is assumed that the amplitude of the stator S and the amplitude of the rotor 3 are the same.
You. Resonant frequency f of stator S _SAnd the rotor 3 vibrates
In the state where the rotor 3_ThreeIs the amplitude A of the stator S _S
Smaller. Therefore, when the amplitude of the stator S is set to 1,
In this case, the amplitude A of the rotor 3_ThreeIs the desired size 1 / X and
So that the resonance frequency f of the rotor 3_ThreeTo decide
Should be designed. [0018] As described above, according to the present invention, a buffer member is provided.
Vibration driven by the traveling wave generated in the relative motion member
Transmission to members can be prevented. for that reason,
Prevents noise generated between the relative motion member and the driven member
can do. In addition, the driven member and the relative movement member
Prevents the traveling force of traveling waves from being generated during
Wear. In addition, the housing containing the ultrasonic motor
Even if the material is supported, it is transmitted to the housing via the driven member.
Vibration can be reduced, and the housing resonates to reduce noise.
The phenomenon that occurs can also be prevented. As a result, noise
Using equipment with ultrasonic motor as drive source
Does not give any discomfort.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A is a plan view of an ultrasonic motor according to an embodiment of the present invention, and FIG. 1B is a cross-sectional view of the ultrasonic motor. FIG. 2 is a sectional view when the ultrasonic motor is unitized. FIGS. 3 (A) and 3 (B) are structural views showing the shape of a rotor of the ultrasonic motor. FIG. 4 is an explanatory view showing the driving principle of the ultrasonic motor. A graph showing a characteristic curve of the input frequency and amplitude of [Description of reference numerals] 1 ... Elastic body 2 ... Piezoelectric elements 3, 31, 32 ... Rotor S ... Stator

Continuation of front page    (72) Inventor Kazuo Hakamada               1-6-3 Nishioi, Shinagawa-ku, Tokyo, Japan               Nikon Oi Plant Co., Ltd.                (56) References JP-A-61-244280 (JP, A)                 JP-A-59-110388 (JP, A)

Claims (1)

(57) [Claims] An elastic body formed in an annular shape and an electromechanical transducer mounted on the elastic body, and a traveling signal traveling in a circumferential direction of the elastic body is generated by a driving signal applied to the electromechanical transducer. A vibrator, a traveling wave that travels in the same direction as the traveling wave is generated by the traveling wave, and a relative motion member that performs relative motion between the vibrator and the driven member that moves integrally with the relative motion member A member, and a buffer member disposed between the relative movement member and the driven member so as not to transmit the vibration caused by the traveling wave generated in the relative movement member to the driven member. Ultrasonic motor. 2. The ultrasonic motor according to claim 1, further comprising a housing that stores the vibrator and the relative motion member,
An ultrasonic motor, wherein the housing movably supports the driven member.