JP2698412B2 - Vibration wave device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a vibration wave device, and more particularly to a vibration wave device using a progressive vibration wave.

[Conventional technology]

In recent years, a vibration wave motor that generates a progressive vibration wave in an elastic body and moves a moving body such as a rotor by this vibration is small in size and can obtain a high torque at a low speed. Adopted for

FIG. 2 is a longitudinal sectional view of a photographing lens of a single-lens reflex camera in which a vibration wave motor is incorporated for driving a photographing lens, and 1 is an annular metallic elasticity around the optical axis L of the photographing lens. In the body, a groove 1A having a predetermined width t and a depth h is provided over the entire circumference as shown in FIG. A piezoelectric element 2 such as PZT is fixed below the elastic body 1 with an adhesive. An alternating signal of ultrasonic waves having different phases is applied to the piezoelectric element 2 as an electro-mechanical energy conversion element by a known method, and the elastic body 1 vibrates in response to this signal, thereby causing the vibrating body to vibrate. A progressive vibration wave that rotates in the circumferential direction of the elastic body 1 to be formed is generated. Reference numeral 3 denotes an annular rotor having an end portion which comes into pressure contact with the upper surface of the elastic body 1, and an annular first vibration absorber 5 such as rubber is provided at the other end of the rotor 3 as a moving body. I have. Reference numeral 4 denotes an annular vibration insulator formed of felt or the like. The insulator 4 receives a pressing force from two superimposed disc springs 9 via a felt base 8.

The rotor 3 described above is closely held by the connecting plate via the first vibration absorber 5 described above. The annular connecting plate 22 is fixed to the output transmission body 25 by six fastening screws (not shown).
The output transmission body 25 that rotates about the optical axis L is a ball.
The ball races 13 and 14 are used to configure a ball bearing. The ball races 13 and 14 are fixed to the outer cylinder 12 of the photographing lens, and the outer cylinder 12 is connected to the fixed cylinder 11 and fixed to the camera mount 19. The connecting roller 15 is fixed to the tip of the output transmission body 25, and engages with a keyway (not shown) of the moving ring 17 holding a focusing lens 27 provided in the optical axis direction. Fixed inner cylinder
The screw portion 18a of the moving ring 17 and the screw portion 17a of the moving ring 17 are helicoidally connected, and the connecting roller 15
The movable ring 17 can move in the optical axis direction while rotating via the.

In such a configuration, the AF signal from the camera or
The vibrating body 1 is driven by a driving signal from the manual ring 16.
2, a progressive vibration wave is generated by a known method, the rotor 3 is rotated, and finally the focus lens 27 is moved in the optical axis direction to perform focus adjustment.

In the case of such a conventional apparatus, the vibrators 1 and 2 are formed of uniform members so that the driving progressive vibration wave has the same amplitude and the same wavelength at any position on the vibrator, and as shown in FIG. Had a substantially uniform structure.

[Problems to be solved by the invention]

However, in the above-described conventional apparatus, a traveling vibration wave having an order (different wavelength) different from the driving traveling vibration wave of the driving order grows, and noise may be generated.

[Means to solve the problem]

SUMMARY OF THE INVENTION The present invention provides a vibration wave device which solves such a problem and suppresses noise generation. The invention according to claim 1 is provided with an electro-mechanical energy converting means having a positional phase difference, In a vibration wave device having an elastic body that excites a plurality of standing waves that are displaced from each other to form a driving traveling vibration wave, a plurality of grooves are formed in the elastic body at substantially equal pitches, and The dynamic rigidity is changed, and the elastic body of the vibration wave device or another member of the vibration wave device to which the vibration wave of the elastic body is transmitted is excited by the elastic body by the electro-mechanical energy conversion means. The vibration wave device is characterized in that the dynamic rigidity at a position of an integral multiple or almost an integral multiple of a half wavelength thereof is further changed as viewed in a vibration mode that vibrates in a different order from the driving vibration mode.

The invention according to claim 2 is characterized in that, when viewed in a vibration mode that vibrates at a different order from the driving vibration mode excited by the elastic body, the elastic body is positioned at an integer multiple or almost an integral multiple of a half wavelength thereof. A feature of the vibration wave device is that the dynamic rigidity is further changed by changing the depth of the groove from other grooves.

〔Example〕

FIG. 1 is a perspective view of an essential part of an elastic body 1 of a vibration wave motor and a piezoelectric element 2 as an electro-mechanical energy conversion element in an imaging lens for a single-lens reflex camera to which the present invention is applied.
Since the first illustrated photographic lens is substantially the same as that of the photographic lens shown in FIGS. 2 and 3, only the elements different from the second illustrated photographic lens will be described, and the description of the other elements will be omitted. In FIG. 1, reference numeral 1 denotes an annular elastic body which forms a main component of the vibration wave motor, and has a width t ₁ and a depth h ₁ on a contact surface with a rotor 3 (see FIG. 2) as a moving body. Are provided over the entire circumference. Also some of these grooves has a deep groove depth h ₂ as illustrated as 1B. When the number of vibration waves that generate noise is, for example, three (hereinafter, the bending vibration when this number of waves occurs in the elastic body 1 is referred to as a third-order mode bending vibration, and the n waves are elastic bodies). 1 is called bending vibration of the nth mode), six deep grooves 1B are provided at pitch θ = 60 ° intervals. When the number of bending vibration waves that generate noise is n, that is, when the bending vibration is in the nth-order mode, this deep groove 1B is pitched. Are provided on the elastic body 1 at intervals of. Reference numeral 2 denotes a piezoelectric element such as PZT as an electro-mechanical energy conversion element, which is adhered to one end surface of the elastic body 1 with an adhesive in the same manner as in the conventional device shown in FIG. Each area forming the A-phase drive area of the piezoelectric element 2
2A ₁ to 2A region ₇ and each of the areas 2B ₁ ~2B ₇ forming the B phase driving area is polarized in different polarization directions alternately as in the first illustrated, also areas 2A ₁ and B-phase driving in the A phase driving area a phase between the area 2B ₁ in the region common to each of the B phase driving area, a common electrode 2C which is connected to the ground of the drive source (not shown) is provided. The A-phase, the areas 2A to form the B phase driving area _{1 ~2A 7,} 2B _{1 ~2B}
The width of ₇ is set to 1/2 of the wavelength λ of the bending vibration of the elastic body 1,
Further, the sum of the widths of the common electrode 2C and the sensor electrode 2D is set to the wavelength λ. The common electrode 2C and facing forming the A phase driving area which are provided on a side electrode on the regions 2A ₁ to 2A region ₇ is connected to the first AC power supply (not shown). Also the common electrode
2C and electrodes on the areas 2B ₁ ~2B ₇ forming the B phase driving area which are provided on opposite sides the output signal of the AC power source and
It is connected to a second AC power supply (not shown) that outputs an AC signal having a phase difference of 90 °. And the A-phase driving areas 2A ₁ to 2A region ₇ respectively and the area 2A ₁ ~2A ₇ B phase driving area corresponding to each of the
Each of 2B _{1 and} 2B ₂ is provided at a distance of λ / 4.

The operation of the photographic lens having such a configuration will be described. When an AC signal is supplied to the A-phase driving area and the B-phase driving area of the piezoelectric element 2 by the first and second AC power sources, the piezoelectric element 2
The bending vibration generates a progressive vibration wave composed of eight waves in the elastic body 1, in other words, a progressive vibration wave of an eighth order mode, and the rotor 3 (see FIG. 2) causes the optical axis to move. L
Rotate around. As a result, the focus lens 27 moves along the optical axis L to perform a focusing operation.

The above description is of the operation when the vibration wave motor operates normally. However, during the operation or at the start of the operation, bending vibration in the nth mode, which may generate noise, for example, bending vibration in the third mode, The operation when it occurs on the elastic body 1 will be described below. In the case of an elastic body having a non-uniform structure as shown in FIG. 1, the natural frequency of the elastic body 1 in a third-order mode vibration wave having a node at the deep groove 1B is high, while the anti-node at the deep groove 1B. The natural frequency of the elastic body 1 in the third-order mode vibration wave is lower than the above-described natural frequency. As described above, since the natural frequency of the elastic body 1 at each position of the tertiary mode vibration wave is different, there is a possibility that noise may be generated.
The vibration wave of the next mode cannot be a traveling wave, so that even if the vibration wave of the third mode is generated for some reason, it does not generate noise.

In the first embodiment, the predetermined position of the elastic body 1, that is, the λ of the tertiary mode vibration wave
A deep groove 1B for making the dynamic rigidity of the elastic body 1 partially non-uniform is provided at a position corresponding to an integral multiple of 1/2 (hereinafter γλ / 2, where γ is an integer). Conversely, even if the groove at the position is made shallower to make the dynamic rigidity 1 of the elastic body partially non-uniform, the same effect as described above is produced.

In the above-described embodiment, the position on the elastic body 1 corresponding to γλ / 2 (of course, approximately γλ / 2) of the wavelength λ of the vibration wave that may generate noise (in the case of the vibration wave of the nth mode) Γλ / 2 of the wavelength λ of the vibration wave of the nth mode or almost γ
(a position on the elastic body 1 corresponding to λ / 2), but the elastic body 1 is a uniform elastic body as shown in FIG.
The predetermined position of the annular vibration insulator 4 shown in FIG. 2, that is, γλ of the wavelength λ of the vibration wave that may generate noise.
Notches (see FIG. 1), non-uniform portions may be provided by holes or the like at positions corresponding to / 2 or approximately γλ / 2, and a similar measure may be taken for the vibration absorber 5 shown in FIG. May be applied to the output transmission body 25. In other words, the predetermined position of the component of the vibration wave motor or the component of the device connected to the motor, that is, λ of the vibration wave that may generate noise.
By providing the above-mentioned non-uniform portion at a position corresponding to γλ / 2 or almost γλ / 2, noise can be prevented.

FIG. 4 shows another embodiment of the elastic body 1 shown in FIG. 1. A part of the teeth 1C shown in the embodiment shown in FIG. This is an example in which a non-uniform portion is formed on the substrate.

FIG. 5 shows still another embodiment of the first illustrated elastic body 1, which is located at a position corresponding to γλ / 2 of the wavelength λ of the vibration wave that may generate noise, according to the first illustrated embodiment. Groove indicated
A groove 1E of different widths t ₂ is the width t ₁ of 1A, thereby is an example of forming a non-uniform portion in a part of the elastic member 1. The fifth
Although the width of the groove is increased in the illustrated embodiment, the same effect can be obtained even if the width of the groove 1E is reduced.

FIG. 6 shows another embodiment of the first illustrated elastic body 1, wherein γ of the wavelength λ of the vibration wave that may generate noise is used.
By changing the width of the elastic body 1 at a position corresponding to λ / 2 (this embodiment shows an example in which the width is reduced),
This is an example in which a non-uniform portion is provided. Although the vertical groove 1F in FIG. 6 is formed by providing grooves on both the inside and the outside, the groove 1F may be formed with either the inside or the outside groove. The same effect can be obtained by changing the material of the portion of the groove 1F with the material of the other portion.

FIG. 7 shows another embodiment of the first illustrated elastic body 1 and includes a tooth 1C.
A groove 1G is provided in a part of the flat elastic body 1 having no groove, that is, at a position corresponding to γλ / 2 of the wavelength λ of the vibration wave that may generate noise, and an uneven portion is formed in the elastic body 1. It is an example. Note that this portion may be higher than other portions instead of the groove 1G. Although the groove 1G is provided on the upper surface of the elastic body 1 in the embodiment shown in FIG. 7, the same effect can be obtained by providing the groove 1G on the lower surface. Further, a groove (not shown) such as the groove 1G shown in FIG. 7 may be provided on the upper surface of the rotor 3 instead of the elastic body 1.

FIG. 8 shows another embodiment of the first illustrated elastic body 1, and FIG.
This is an example in which a tooth 1H having a wider width than the tooth 1D is provided instead of the illustrated tooth 1D.

FIG. 9 shows still another embodiment of the first illustrated elastic body 1,
Instead of the first illustrated groove 1B, a hole of a predetermined depth is provided at the position of the groove 1B.
FIG. 10 shows an example in which a protrusion is fixed in place of the hole 1J and an uneven portion is provided in the elastic body 1.

Although the above embodiment is an example of an annular vibration wave motor, the present invention can be applied not only to such a vibration wave motor but also to an elastic body having a disc-shaped or elliptical vibration wave motor. Also, the present invention can be applied to a vibration wave motor of a type in which the elastic body itself moves by a progressive vibration wave.

〔The invention's effect〕

As described above, according to the present invention, it is possible to prevent a vibration wave that may generate noise on at least one member of a vibration wave device such as an elastic body, a vibration insulator, and an output transmission body from growing into a traveling wave. As a result, noise, which has been a major problem in practice, can be suppressed.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of an essential part of a vibration wave motor in a photographing lens for a single-lens reflex camera to which the present invention is applied, FIG. 2 is a longitudinal sectional view of a photographing lens to which a conventional vibration wave motor is applied, and FIG. 2 is a perspective view of a main part of a vibration wave motor, and FIGS. 4 to 10 are perspective views of a main part of a vibration wave motor to which the present invention is applied. In the drawing, 1 ... elastic body, 2 ... piezoelectric element, 3 ... rotor, 4 ... vibration insulator, 12 ... outer cylinder constituting vibration wave device having vibration wave motor, 25 ... output transmission body It is.

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Akio Atsuta 770 Shimonoge, Takatsu-ku, Kawasaki-shi, Kanagawa Prefecture Inside the Tamagawa Office of Canon Inc. (72) Inventor Hiroshi Ueda 770 Shimo-noge, Takatsu-ku, Kawasaki-shi, Kanagawa Canon Inc. Tamagawa Business In-house (72) Moto Kanazawa Inventor 770 Shimonoge, Takatsu-ku, Kawasaki City, Kanagawa Prefecture Inside the Tamagawa Office of Canon Inc. (56) References JP-A-62-193569 (JP, A) JP-A-61-116978 (JP, A) JP-A-63-240382 (JP, A) JP-A-63-268476 (JP, A) JP-A-61-116979 (JP, A)

Claims (2)

(57) [Claims] 1. A vibration device comprising an electro-mechanical energy conversion means having a positional phase difference, comprising: an elastic body which excites a plurality of standing waves having positional phases shifted from each other to form a driving traveling vibration wave. In the wave device, a plurality of grooves are formed in the elastic body at substantially equal pitches to change dynamic stiffness at groove positions, and the elastic wave of the vibration wave device or the vibration wave of the elastic body is transmitted. Other members of the vibration wave device are viewed as a vibration mode that vibrates at a different order from the driving vibration mode excited by the electromechanical energy converting means to the elastic body, and are an integral multiple of a half wavelength or almost an integer. A vibration wave device characterized by further changing the dynamic rigidity at the double position. 2. A groove of the elastic body at a position which is an integral multiple or almost an integral multiple of half a wavelength of the vibration mode when viewed in a vibration mode which vibrates at a different order from the driving vibration mode excited by the elastic body. 2. The vibration wave device according to claim 1, wherein the dynamic stiffness is further changed by changing the depth of the other groove.