JP2563290B2 - Vibration wave drive - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a vibration wave driving device for driving a moving body by a progressive vibration wave generated on a vibrating body, and particularly to a structure for preventing rotation of the vibrating body. It is about.

(Background of the Invention) A vibration wave motor converts an oscillating motion generated when a frequency voltage is applied to an electrostrictive element into a rotary motion or a one-dimensional motion, and requires a winding wire as compared with a conventional electromagnetic motor. Therefore, the structure is simple and compact, and high torque can be obtained even at low speed rotation, which has been attracting attention in recent years.

FIG. 3 and FIG. 4 are for explaining the driving principle of the vibration wave motor having the conventional structure, and FIG. 3 shows the generation state of the vibration wave of the motor. In this figure, reference numeral 15 indicates a vibrating body (usually made of a metal material).
The two groups of electrostrictive elements 14a, 14b adhered to one side of the are arranged at positions that are appropriately separated, specifically, to spatially satisfy the phase shift of λ / 4 with respect to the progressive vibration wave λ. ing.

In the example of FIG. 3, the vibrating body 15 is one electrode of each of the electrostrictive elements 14a and 14b, and the electrostrictive element 14a of one of these groups is connected to the AC power source 16a from v = v ₀ sinωt. .. (1) AC voltage is applied, and the other group of electrostrictive elements 14b is deviated by λ / 4 phase through 90 ° phase shifter 16b v = v ₀ sin (ωt ± π / 2). .. By applying the AC voltage of (2), progressive vibration waves can be obtained.

It should be noted that (+) and (-) in the equation (1) represent the directions in which the moving body 17 is moved, and can be switched by the 90 ° phase shifter 16b as necessary. Is
The 90 ° phase shifter 16b is switched to the (-) side, and therefore the electrostrictive element 14b is applied with a voltage of v = v ₀ sin (ωt-π / 2).

Here, the relationship between the applied AC voltage and the generated oscillating wave when an AC voltage is applied to each of the electrostrictive elements alone or simultaneously is described.First, a predetermined AC voltage is applied only to the electrostrictive element 14a. Considering the case where (i.e., the voltage v = v ₀ sinωt) is applied independently, the vibrating body 15 is oscillated by a standing wave as shown in FIG. On the other hand, in the same manner, the voltage v = v ₀ sin is applied to the electrostrictive element 14b alone.
When (ωt−π / 2) is applied, the vibrating body 15 vibrates due to a standing wave as shown in FIG. 3B.

On the other hand, when the two AC voltages having the above-mentioned phase shifts are simultaneously applied to the electrostrictive elements 14a and 14b, the oscillating wave is obtained as a progressive wave. The outline of the temporal change of this progressive oscillatory wave is simply shown as (a), (b), (c), and (d) in FIG. 3, where (a) is the time t = 2nπ / ω. , (B) is time t = π / 2
ω + 2nπ / ω, (c) shows the state of the vibration wave at time t = π / ω + 2nπ / ω, and (d) shows the state of the vibration wave at time t = 3π / 2ω + 2nπ / ω, and the wavefront of the vibration wave is in the x direction in the figure. proceed.

The progressive vibration wave obtained as described above is accompanied by a longitudinal wave and a transverse wave. Specifically, at an arbitrary point A of the vibrating body 15, as shown in FIG. w
It makes a spheroidal motion counterclockwise in the figure with. In addition, the surface of the vibrating body 15 that vibrates in this way has a moving body.
Since 17 is in pressure contact, contact with each vertex of the vibrating surface of the driving body (actually making a surface contact with a certain width) causes the moving body 17 to reach each vertex A of the vibrating body. , A '...
The driving force by the component of the vertical amplitude u of the elliptic motion is applied from, and the moving body 17 is moved in the direction of the arrow N in the drawing (rotation if the moving body is a rotor).

If the transfer is shifted in the + 90 ° direction by the 90 ° phase shifter 16b, the oscillating wave travels in the -x direction, thus
Needless to say, 17 moves in the direction opposite to the N direction.

Further, since the vibration wave motor described above frictionally drives the moving body by the vibration of the vibrating body, it is usually used by resonating the vibrating body in a desired vibration mode so as to generate a large vibration in the vibrating body. Is normal.

By the way, it is general that the support structure of the vibrating body in the above-mentioned vibration motor is constituted only by making pressure contact with a vibration absorbing material such as felt for the purpose of reducing the vibration load of the vibrating body. . However, with such a configuration, when the moving body such as the rotor has a high load, the vibrating body which receives a reaction force when the moving body is driven is moved in a direction opposite to the driving direction of the moving body. There was a problem. For example, when the vibration wave motor is incorporated as a driving means for a lens barrel of a single-lens reflex camera or the like, if there is the above problem, the vibrating body is displaced from the reference position,
There is a great risk of impairing accurate control such as focus adjustment that should be controlled by the vibration wave motor.

Therefore, some conventional proposals have been made for the purpose of solving such problems. One of the conventional proposals is considered to be that the vibrating body (annular stator or the like) has a structure having a comb-shaped contact portion and that an AC voltage is applied to only one of the electrostrictive elements 14a and 14b. In this case, a rotation stopper (claw, etc.) extended from an appropriate fixing portion (stator) is inserted into the comb-shaped slit at the node position (or antinode position) of the standing wave. It has an engaged structure.

However, according to the vibration wave motor having such a structure, although the above-described movement stop of the moving body is realized for the time being, there is a problem that another problem as described in FIG. 5 is caused.

The vibration wave motor shown in FIG. 5 (a) has a structure in which a piezoelectric element 12 is integrated with the lower surface of an elastic body 11 having a plurality of slits (grooves) 14 and extended from a fixed portion. In addition, a plurality of claws 13 for stopping rotation are inserted and engaged with each other, and the contact points between the plurality of claws 13 and the vibrating body are P ₁ ′ ~
It is indicated by P ₄ ′. Then, in this case, the contact points P ₁ ′ to P ₄ ′ are arranged at each position of the node Q ′ on the assumption that the vibration wave obtained in the vibrating body is the above-mentioned standing wave, and therefore these contact points are arranged. The separation gap l between P ₁ ′ and P ₄ ′ coincides with half the wavelength λ of the vibration wave. This state is shown in FIG. 5 (b). The vibration wave actually obtained by this vibration wave motor is the progressive wave described in FIGS. 3 (a) to 3 (d). Therefore, it is natural that the contact points P ₁ ′ to P ₄ ′ come to the position corresponding to the antinode R ′ of the standing wave as shown in (c) of FIG. This means that even with the method of arranging the contact points P ₁ ′ to P ₄ ′ at each antinode position of the standing wave, substantially the same result as in the example of FIG. 5 is obtained.

However, when the vibration wave motor has the above-mentioned structure, the claw 13 as a rotation stopper that contacts the vibrating body 18 in the slit 14 functions as the rotation stopper described above, and at the same time, the vibration It also exists as an object that interferes with the vibration of the body 18, and may cause a bad influence on the vibration generated in the vibrating body by the pawl 13 that is the vibration obstructing object. In other words, the claw 13 causes a discontinuity point of the vibration wave, and the greater the resistance (load) of such vibration, the higher the rigidity of the elastic body 11 constituting the vibration body. The resonance point of the elastic body becomes high, which hinders efficient driving of the vibration wave motor.

Then, the present inventor conducted further detailed investigations, and the following was revealed.

That is, strictly speaking, the influence of the vibration resistance due to the contact of the rotation stopper with respect to the vibrating body fluctuates as the progressive vibration wave progresses, so that the vibration occurs between (b) and (c) in FIG. Although the resonance point of the body fluctuates, on the other hand, when the drive wave motor is driven at high speed, the drive frequency of the motor becomes constant, and as a result of these, a temporary phenomenon of deviation of the resonance point is caused. It was found that the output would be reduced by that amount. Here, the reason why the vibration resistance varies due to the contact of the rotation stopper is explained as follows. That is, if it is assumed that the progressive vibration wave is in the state of FIG. 5 (b), the minimum amplitude position of the vibration wave coincides with the contact point with the pawl of the rotation stopper, The resistance from the
If the state is in the state of (c) in the figure, the maximum position of the amplitude of the vibration wave coincides with the contact point with the pawl of the rotation stopper, and the resistance from the pawl becomes extremely large. As a result, the resistance (load) change at the discontinuity point of the vibration wave, which is the contact point of the claw, as described above, also causes a change in the resonance point that causes a reduction in output.

(Object of the Invention) The present invention has been made in view of the above problems,
It is an object of the present invention to eliminate the above-mentioned drawbacks and to provide a vibration wave drive device having a structure in which the movement of the vibrating body is reliably stopped and the adverse effect on the vibration of the vibrating body is minimized.

(Summary of the Invention) Therefore, the characteristic of the vibration wave driving device according to the present invention made to realize such an object is that a progressive vibration wave having a wavelength λ is generated, and a plurality of vibration waves are provided all around. A vibration wave drive device comprising: a substantially ring-shaped vibrating body having a groove formed therein; and detent means in the traveling wave traveling direction that is inserted into the groove and contacts the vibrating body. Is inserted into and engaged with a plurality of grooves selectively selected from the plurality of grooves of the entire circumference, and the distance between the contact positions of the plurality of detent means and the vibrating body is determined by the progressive vibration wave. Is set to a length that does not match a multiple of (1/2) nλ (n is an integer) given by the wavelength λ of.

The groove in the direction orthogonal to the traveling direction of the vibration wave of the vibrating body in the above configuration, for example, when the vibrating body is a shape having a contact portion of a tooth-like structure that is effective in amplifying vibration, It goes without saying that the slits of the comb teeth can be used as they are as the grooves.

The vibrating body is composed of, for example, electro-mechanical energy conversion elements arranged or polarized topologically, and has two groups of electrostrictive elements having a spatial arrangement relationship suitable for generating progressive vibration waves. The body can be exemplified, and a known body can be applied.

In the above configuration, the separation gap l between the contact positions of the plurality of detent means and the vibrating body is set to the progressive vibration wave of the wavelength λ. The length that does not correspond to a multiple of (n is an integer) is set so that the width of the fluctuation of the vibration resistance (and thus the fluctuation of the resonance point) that accompanies the progress of the vibration wave is averaged over the entire vibrating body. In order to make the size as small as possible, it may be designed by selecting the separation gap 1 regularly or randomly corresponding to each vibration wave motor having a specific structure in accordance with the purpose. That is, since the vibration resistance of the vibrating body at the contact point between the plurality of detents and the vibrating body fluctuates between the minimum and the maximum in a cycle of 1 / 2λ of the progressive vibration wave, It suffices to set the spatial arrangement of these contact points so as to shift the variation phase of the points. Particularly preferably, It is preferable to set the separation gap 1 in the relationship of (n: odd number).

(Embodiment of the Invention) The present invention will be described below based on an embodiment shown in the drawings as a rotor type vibration wave motor.

FIG. 2 is an exploded view of an example of the configuration outline of the vibration wave motor according to the present invention. In FIG. 2, reference numeral 1 is a ring-shaped elastic body having flexible elasticity. ) Is formed by. The elastic body 1 has an isosceles trapezoidal shape with a narrow width on the upper surface side, and a plurality of concave groove type radial slits 1a are formed on the upper surface at predetermined intervals along the traveling direction of the vibration wave. Are formed. Further, a piezoelectric element 2 is integrated with the lower surface of the elastic body 1 by adhesion, and this piezoelectric element 2 is 8 in the circumferential direction in this example.
It is polarized so that a progressive oscillatory wave is generated.

Reference numeral 9 denotes a flexible wiring board, which is an electrode group (A phase, B phase, C phase) drawn from the flexible wiring board 9 with respect to the electrode surface formed on the lower surface of the piezoelectric element 2.
Phase, S phase) are adhered (or pressure welded).

The elastic body 1, the piezoelectric element 2, and the flexible wiring board 9 constitute a stator S as a vibrating body.

Reference numeral 3 denotes a rotation (movement) stopper for preventing the stator S from rotating in the circumferential direction, and a plurality of (five in this example) inward projecting claws 3a are formed on the inner edge of the ring type at predetermined intervals. ing. The claw 3a is fitted and engaged with the slit 3a of the elastic body 1. This rotation stopper 3 is a lower base 8 which is a fixed part.
It is fixed by three screws 10 against.

The base 8 in this example is for supporting the whole vibration wave motor, and includes a disc spring 7 for pressing and a holding plate 6.
Also, the stator S is supported via the felt 5 and the felt 5, and the vibration of the stator S is absorbed.

Reference numeral 4 denotes a rotor as a moving body, a thin brim-shaped member 4a is provided on the inner edge of the base 4c, and the lower surface thereof is the elastic member
Is in frictional contact with the upper surface of the. Further, a vibration absorbing rubber 4b is attached to the upper surface of the rotor 4,
It is provided in a structure that does not transmit vibration to an output system (not shown) arranged above the rotor 4. As an example of a specific structure for not transmitting this vibration, a structure of a type in which the rotor 4 is pressed against the substrate 8 by a bearing (not shown) can be exemplified.

The features and operating principle of the vibration wave motor of this example, the structure of which is outlined in FIG. 2, will be described below with reference to FIG.

In the vibration wave motor of this example, as shown in FIG. 1 (a), the slit 1 of the elastic body 1 is used for 1/2 of the wavelength λ of the progressive vibration wave.
The spacing l between the engaging contact points P _{1 to} P ₃ between the claw 1a of the rotation stopper 1 and the elastic body 1 inserted in a (that is, the interval between discontinuous points of the progressive vibration wave) is The arrangements are not in a multiple relationship, that is, the arrangements are disjoint. Specifically, the wave number of the traveling wave is set to 8 waves, the number of slits of the elastic body is set to 90 at an equal pitch, and the claws 3a of the rotation stopper 3 are set to 5 at an equal pitch.

With such an arrangement relationship, for example, when the vibration wave 21 travels from the state (b) of FIG. 1 to the state (c) of FIG. 1, the contact point P in the state of FIG. ₁ exists in correspondence with Q ₁ corresponding to the node in the standing wave, but other contact points P ₂ and P ₃ do not correspond to Q _{2 to} Q _4, and In the state of (c) in the figure, the contact point P ₁ exists in agreement with R ₁ corresponding to the antinode of the standing wave, but the other contact points P ₂ and P ₃ are R ₂ to R _{2. 4} does not match, and after all, when considering the whole stator S which is a vibrating body, the sum of the vibration resistance received from the discontinuity point in both the states (b) and (c) of FIG. It will be obtained without much difference.

This means that the fluctuation amount of the total vibration resistance accompanying the progress of the progressive vibration wave is smaller than that of the vibration wave motor having the configuration shown in FIG. 5, and therefore the deviation from the resonance point of the vibrating body is also caused. Since the number is small, the effect of suppressing the output reduction during the driving of the vibration wave motor can be obtained.

As described above, in the vibration wave motor of the present invention, it is assumed that the vibration resistance fluctuates within the range of the minimum to the maximum at each of the contact points, and the vibrating body has a plurality of such contact points. In addition to averaging the fluctuations of the vibration resistance as a whole over time and suppressing the fluctuations, this made it possible to minimize the deviation from the resonance point and minimize the output down. Needless to say, the invention is not limited to the above-described embodiments, and various modifications of the vibration wave motor can be configured without changing the gist of the invention. For example, the same effect can be obtained not only when the separation gaps of the claws of the rotation stopper shown in the example of FIG. Further, although the embodiment has been described as a rotor type, it goes without saying that the same applies to a linear motor.

(Effects of the Invention) As described above, the vibration wave driving device according to the present invention selectively selects from a plurality of grooves on the entire circumference of a substantially ring-shaped vibrating body having a plurality of grooves formed on the entire circumference. In multiple grooves,
A plurality of detents are inserted into and engaged with each other, and the positional interval l between the groove and the contact portion of the detent is set to the wavelength λ of the progressive vibration wave. By configuring the length so that it does not match a multiple of (n is an integer), it is possible to suppress the fluctuation of the vibration resistance of the vibrating body, which adversely affects the progressive vibration wave, to the smallest possible state. In addition, since the movement of the vibrating body is stopped by the plurality of contact portions, the stress applied to the vibrating body can be dispersed, and a further effect can be obtained in suppressing the adverse effect on the vibration of the vibrating body. is there.

Further, according to the structure of the present invention, in the vibrating body having a plurality of grooves formed in the entire circumference effective for amplifying the vibration, the groove is inserted into the insertion member such as the detent claw serving as the movement preventing means of the vibrating body. It can also be used as a joint part, and it is also possible to realize multifaceted utilization of the structure, such as the formation of a recess provided only on the vibrating body for engaging with the fixed body is unnecessary, and therefore the number of processing steps is relatively small. There is an effect that a plurality of functions can be satisfied at the same time with a simple structure.

When the moving body of the vibration wave drive device generates a high load, the moving body of the present invention is more suitable than the conventional type structure in which a thin detent is conventionally adhered to the vibrating body. The structure realizes a strong detent for the moving body, and because this detent is formed as a mechanical engagement relationship, it does not cause a decrease in strength of the adhesive surface due to aging and temperature changes. In addition, there is an effect that the reliability and durability of the device are improved.

[Brief description of drawings]

Drawing FIG. 1 is a diagram for explaining the principle configuration and operation of a vibration wave driving device according to the present invention, FIG. 2 is a component exploded view showing an example of the configuration outline of the vibration wave driving device, and FIG. For explaining the basic configuration and operation of the vibration wave motor of FIG. 4, FIG. 4 is a view for explaining the operation principle of the vibration wave motor, and FIG. 5 is the principle of another conventional vibration wave motor. It is a figure for demonstrating a structure and operation. 1: Elastic body (vibrating body), 1a: Slit 2: Pressure transmission element 3: Rotation stop, 3a: Claw 4: Rotor, 4a: Rotor contact part 4b: Vibration absorbing rubber, 4c: Rotor base 5: Felt, 6: Presser Plate 7: Disc spring, 8: Base 9: Flexible wiring board 10: Fixing screw, 11: Elastic body 12: Piezoelectric element, 13: Claw 14a: Electrostrictive element, 14b: Electrostrictive element 16a: AC power supply, 16b: 90 ° phase shifter 15: Vibration body, 17: Moving body 18: Vibration body, 21: Progressive vibration wave

Claims (1)

(57) [Claims] 1. A substantially ring-shaped vibrating body for generating a progressive vibration wave having a wavelength λ, wherein the vibrating body is inserted and engaged in the groove. In a traveling wave traveling direction in contact with a traveling wave traveling direction, the demobilization means is inserted into and engaged with a plurality of grooves selectively selected from a plurality of grooves of the entire circumference. ,
The spacing between the contact positions of the plurality of detent means and the vibrating body is set to a length that does not match a multiple of (1/2) nλ (n is an integer) given by the wavelength λ of the progressive vibration wave. An oscillatory wave drive device characterized in that