JP3124284B2 - Vibration wave drive - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a vibration wave driving device.

[Prior art] As a conventional vibration wave motor as a vibration wave driving device, a camera that generates a progressive bending vibration in an annular metal vibration elastic body and drives a moving body by a frictional force is known as a camera. It is used in the autofocus (AF) mechanism of the camera.

However, since this type of vibration wave motor has a ring-shaped vibration elastic body, it tends to be expensive as a unit including a pressurizing mechanism for obtaining frictional force, and requires hollowness (ring shape). There is a disadvantage in terms of cost as an application that is not performed.

Therefore, a motor as shown in FIGS. 7 and 8 has been proposed as a vibration-wave motor of a rod-like shape such as a pencil type having a simple configuration of a pressurizing system.

A is a pencil-type vibrator, in which donut-shaped piezoelectric element plates 3 and 4 are provided between a pencil-shaped front vibration elastic body 1 and a cylindrical rear vibration elastic body 2, and these piezoelectric element plates 3 and 4 are provided. Four
For example, an electrode plate (not shown) for applying an alternating voltage as an alternating signal is inserted between, for example, the piezoelectric element plates 3 and 4, and a bolt 6 is provided between the front vibration elastic body 1 and the rear vibration elastic body 2. The piezoelectric element plates 3, 4 and the electrode plate are sandwiched and fixed.

The piezoelectric element plates 3 and 4 are polarized with different polarities symmetrically in a cross section passing through the axis, and the piezoelectric elements 3 and 4 are arranged at an angle of 90 ° in the θ direction.

When AC voltages V ₁ and V ₂ having frequencies close to the bending natural frequency of the vibrator are applied to the respective piezoelectric elements, the piezoelectric elements expand and contract in the thickness direction, and the vibrator performs bending vibration. In this case, the AC voltages V ₁ and an AC voltage V _2, for example the same amplitude and frequency are both the temporal phase has a Child of 90 degrees, the vibrator A is the rope skipping around its axis A circular motion like a rope (hereinafter referred to as a rope skipping vibration) is performed. In addition, by reversing the phases of the AC voltages V ₁ and V ₂ , forward and reverse rotation of the circular motion becomes possible.

On the other hand, R is a rotor that is fitted coaxially with the axis l of the vibrator A, and one end of the fitted is pressed against the sliding portion B of the vibrator by the spring force of the spring 5 to be excited by the vibrator A. Rotation is driven by friction due to vibration. The spring 5 has a tip of a bolt 6 and
It is elastically mounted between a flanged thrust bearing 7 and a spring post 8 fitted thereto.

[Problems to be Solved by the Invention] In such a vibration wave motor, it is required that the piezoelectric element plate 3 and the piezoelectric element plate 4 have the same natural bending frequency. Due to processing errors of the plates 3, 4 and the bolts 6, processing errors of the electrode plates, connection terminal portions protrudingly formed on the electrode plates, solder for wiring fixed to the terminal portions, and the like. There may be a difference between the two bending natural frequencies described above, and particularly, the piezoelectric element plates 3 and 4
The influence of the eccentricity and the terminal part of the electrode plate was great.

When the natural frequencies of the drive modes are separated, a plurality of bending modes are generated at frequencies near the natural frequency, and it becomes difficult to excite vibrations of necessary amplitude and phase when obtaining circular or elliptical motion.

For this reason, the required number of rotations and torque cannot be obtained or fluctuate, a large loss occurs, and the efficiency is low.

It is an object of the present invention to solve such a conventional problem and to provide a vibration wave driving device capable of adjusting a natural frequency of a plurality of bending mode vibrations formed in a vibrator.

[Means for Solving the Problems] A configuration for realizing the object of the present invention is to apply an alternating signal to an electro-mechanical energy conversion element arranged on a rod-shaped elastic body having an outer diameter to apply a signal to the elastic body. A vibrator for causing the elastic body to perform a circular or elliptical motion about an axis by giving vibrations of a plurality of bending modes having the same shape but different directions with a temporal phase difference, and In the vibration wave driving device in which the contacting body and the vibrator move relative to each other due to the circular or elliptical motion, the natural vibration of the plurality of bending modes on the outer diameter of the outer circular elastic body In order to adjust the number, a non-axisymmetric portion with respect to the axis of the elastic body is provided.

[Operation] In the vibration wave driving device having the above-described configuration, the natural frequency can be adjusted by, for example, mass adjustment by the asymmetric portion provided in the elastic body. It is possible to reduce the size.

Embodiment 1 Embodiment 1 FIG. 1 is a perspective view showing Embodiment 1 of a vibration wave motor to which a vibration wave driving device according to the present invention is applied.

In this embodiment, a screw hole is provided in the rear vibrating elastic body 2 of the pencil-type vibrator A as in the conventional example, and a screw 13 is provided in this hole so that it can be screwed along, for example, a radial direction.

In the present embodiment, the mounting position of the screw 13 is provided, for example, in parallel with a central portion that bisects the element portion of the piezoelectric element plate 3,
The center of the piezoelectric element plate 4 is shifted by 90 ° from the central part that divides one element part into two.

That is, when the screw 13 is added to the vibrator A, the axial symmetry of the vibrator is lost, and the two natural frequencies having different phases of 90 ° are degenerated and separated.

Therefore, when the screw is taken in or out or the length of the set screw is changed, the natural frequency difference (Δf) changes, and the natural frequency difference (Δf) can be adjusted.
It is possible to adjust the processing error of the terminal portion 11 of 10, the influence of natural vibration due to the soldering of the lead wire 12, and the like.

In the present embodiment, the screw 13 can be screwed in the center direction. However, this is not necessary, and a plurality of screws may be provided.

Second Embodiment FIG. 2 shows a second embodiment.

In this embodiment, a slit 2a is provided on the bottom peripheral wall of the post-vibration elastic body 2, and the natural frequency difference (Δf) is adjusted by adjusting the position of the slit 2a. The post-vibration elastic body 2 can be rotated by slightly loosening the screw 6.

Third Embodiment FIG. 3 shows a third embodiment.

In the above-described second embodiment, the natural vibration frequency difference is adjusted by providing a slit in the post-vibration elastic body 2 and rotating the post-vibration elastic body 2 to adjust the position of the slit. In this embodiment, a notch 14 is provided in the peripheral portion of the rear vibration elastic body 2 instead of the slit.

Fourth Embodiment FIG. 4 shows a fourth embodiment.

In the first embodiment shown in FIG. 1, a screw 13 is provided on the rear elastic body 2 so as to be screwable, but in this embodiment, a shaft 13 is used instead of the screw 13.
The natural frequency difference is adjusted by projecting the shaft 15 and breaking the shaft 15 by a necessary amount.

Fifth Embodiment FIG. 5 shows a fifth embodiment.

In this embodiment, an adjustment ring 16 having an adjustment projection 17 is fixed between the elastic bodies 1 and 2 coaxially with the piezoelectric element plates 3 and 4, and the natural frequency difference is adjusted by bending the projection 17.

Sixth Embodiment FIG. 6 shows a sixth embodiment.

In this embodiment, an adjusting plate 18 for adjusting the mass is provided at the rear end of the post-vibration elastic body 2, and the elastic body 2, the piezoelectric element plate, and the electrodes are provided together with the adjusting plate 18 by bolts 6 ′ having hexagonal holes 6 a. A plate or the like is pinched and fixed.

In the present embodiment, the natural frequency difference is adjusted by changing the position of the adjusting plate 18 having an unequal length in the radial direction with respect to the axis of the oscillator A, and the adjustment is performed by loosening the bolt 6 '. Plank 18
When rotating, only the adjustment plate 18 can be rotated, and the holding surface between the piezoelectric element plate and the post-vibration elastic body can be prevented from moving.

Seventh Embodiment FIG. 9 shows a seventh embodiment.

In the above embodiment, the position of the post-vibration elastic body is changed,
While adjusting the natural frequency difference by adding mass,
By changing the positions of the piezoelectric element plates 3 and 4, it is possible to adjust the natural frequency difference similarly.

In this embodiment, the head of a bolt 6 ′ for fixing the rear vibration elastic body 2 to the front vibration body 1 with the piezoelectric element plates 3 and 4 interposed therebetween is formed to have the same diameter as the rear vibration elastic body 2, and a screw is formed. This facilitates the operation of loosening and tightening.

As shown in FIG. 10, a notch 14 may be provided in the bolt 6 '.

FIG. 11 shows an example of a configuration in which a lens barrel of an optical lens is driven using a motor according to the present invention.

Reference numeral 22 denotes a gear coaxially connected to the moving body 8. The lens barrel transmits a rotational output to the gear 23 and has a gear that meshes with the gear 23.
Rotate 24.

An optical encoder slit plate 25 is arranged coaxially with the gear 23 to detect the rotational position and rotational speed of the moving body 8 and the lens barrel 24. Detect speed.

Numeral 27 is a screw which can be screwed in the radial direction, and the same effects as in the first embodiment can be obtained.

[Effects of the Invention] As described above, according to the present invention, the natural frequency of the vibration system excited by the electro-mechanical energy conversion element such as the piezoelectric element plate can be adjusted, and these natural vibrations can be adjusted. It is possible to make them equal or substantially equal, and increase and stabilize the number of revolutions and torque, and improve the efficiency.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a first embodiment of a vibration wave motor to which a vibration wave driving device according to the present invention is applied, and FIGS. 2 (a) and 2 (b).
3 is a longitudinal sectional view and a bottom perspective view showing a second embodiment, and FIGS. 3 (a) and 3 (b) are perspective views and a longitudinal sectional view showing a third embodiment,
4 is a perspective view showing a fourth embodiment, FIG. 5 is a perspective view showing a fifth embodiment, FIGS. 6 (a) and 6 (b) are a perspective view and a longitudinal sectional view showing a sixth embodiment, and FIG. Is a perspective view showing a conventional vibration wave motor, FIG. 8 is a longitudinal sectional view of FIG. 7, FIG. 9 is a longitudinal sectional view of the seventh embodiment, and FIGS. It is a longitudinal section and a perspective view showing a modification. FIG. 11 is a sectional view of an apparatus using a vibration wave motor. A: Vibrator, 1: Front vibration elastic body 2: Rear vibration elastic body, 10: Electrode 11: Terminal section, 12: Lead wire 13: Screw, 14: Notch section 15: Shaft , 16 ... Adjustment ring 17 ... Protrusion, 18 ... Adjustment plate

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Jin Mukaijima 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (56) References JP-A-59-96881 (JP, A) JP-A-63 -240380 (JP, A) JP-A-2-36776 (JP, A) JP-A-62-238101 (JP, A)

Claims (2)

(57) [Claims] 1. An electric device disposed on a rod-shaped elastic body having a circular outer diameter.
By applying an alternating signal to the mechanical energy conversion element, vibrations of a plurality of bending modes having the same shape but different directions are given to the elastic body with a time phase difference so that the elastic body is centered on the axis. A vibrator that performs a circular or elliptical motion as a vibration wave driving device in which the contacting body and the vibrator relatively move by the circular or elliptical motion of the elastic body; A vibration wave driving device, wherein a non-axisymmetric portion with respect to an axis of the elastic body is provided on an outer diameter of a body to adjust a natural frequency of the plurality of bending modes. 2. The apparatus according to claim 1, wherein the contact body is driven to rotate by the circular or elliptical movement of the elastic body, and the driven mechanism is driven by using the rotation of the contact body as a drive source.
The vibration wave driving device as described in the above.