JP2003209983A - Oscillator and oscillation wave driver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an oscillator for an oscillation wave driver in which a shaft can be shortened while increasing an output. <P>SOLUTION: The oscillator excites bending oscillation by applying a driving signal to a piezoelectric element 3 interposed between a first elastic body 1 and a second elastic body 2. A flange-like elastic part 4 having an outside diameter larger than that of the piezoelectric element 3 extends in the direction orthogonal to the axial direction of the oscillator between the first elastic body 1 and the second elastic body 2. Circumferential grooves 7 for enlarging oscillatory displacement are provided in both sides of the flange-like elastic part 4 in the thickness direction. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration wave driving device, and more particularly to a structure of a vibrating body of a rod-shaped vibration wave driving device.

[0002]

2. Description of the Related Art A vibration wave motor, which is one of the vibration wave driving devices, has been used as a product for driving a camera lens or the like, and there are an annular type and a rod type.

FIG. 8 is a block diagram of a vibration wave motor used for driving a camera lens. 9A is a configuration diagram of a vibrating body used in the vibration wave motor of FIG. 8, and FIG. 9B is a diagram showing a vibration mode of the vibrating body.

In these figures, 111 is a first elastic body, 112 is a second elastic body, and 113 is a laminated piezoelectric element which is an electro-mechanical energy conversion element. Reference numeral 115 denotes a shaft, which includes a first elastic body 111 and a second elastic body 112.
Further, the central portion of the laminated piezoelectric element 113 is penetrated, and the tip end portion is coupled to a fixing flange 121 described later. A threaded portion is provided at the other end of the shaft 115, and the first elastic member arranged between the flange portion provided in the central portion of the shaft 115 and the nut 115a is provided by screwing the nut 115a. The body 111, the second elastic body 112, and the piezoelectric element 113 are clamped and fixed by a predetermined force.

Reference numeral 118 denotes a rotor, which has a contact spring having a small contact width on the outer peripheral portion and having an appropriate spring property, and the contact spring is provided on the upper surface of the first elastic body 111. Contact the member 122. Reference numeral 119 is a gear that transmits the output of the motor. A concave portion is provided on one side of the rotor 118 and the gear 119, and a convex portion is provided on the other side. By engaging the concave portion and the convex portion, the rotor 118 and the gear 11 are provided.
9 are mutually regulated in the rotation direction. Reference numeral 120 denotes a pressure spring, which is arranged between the rotor 118 and the gear 119, and applies a pressing force for bringing the rotor 118 into pressure contact with the friction member 122. A fixing flange 121 is fixed to the motor to fix the entire vibration wave motor.

Electrodes of the laminated piezoelectric element 113 are grouped into two electrode groups. When an alternating electric field having a different phase is applied to each of the electrode groups from a power source (not shown), the vibrating body is shown in FIG. 9 (b). The bending vibration in the posture shown and the bending vibration whose displacement direction is orthogonal to this vibration are excited. By adjusting the phase of this applied electric field, it is possible to give a 90-degree phase difference between the two vibrations, and as a result, the vibrating body makes a swinging motion that rotates around the axis and makes contact with it. The rotor 118 is driven to rotate.

[0007]

The rod-shaped vibrating wave motor shown in FIG. 8 achieves miniaturization by reducing the size of the rotor in the radial direction. There is a demand to further reduce the manufacturing cost. In order to meet this demand, it has been proposed to reduce the length of the motor and to make the piezoelectric element, which is relatively high in cost, small in diameter and thin, to realize low cost.
This is shown in FIG.

FIG. 10A is a configuration diagram of the vibrating body, and FIG. 10B is a diagram showing a vibration mode of the vibrating body. In order to reduce the size, as shown in FIG. 10A, the flange-shaped (disk-shaped) elastic body 134 and the piezoelectric element 133 are sandwiched and fixed by the first elastic body 131 and the second elastic body 132, and the vibrating body is formed. The drive surface is provided on the flange-shaped protrusion, and the rotor is arranged on the outer peripheral portion of the first elastic body.

However, such a motor tends to have a smaller vibration speed as the size becomes smaller than that of the conventional rod-shaped vibration motor. Therefore, it seems that there is room for improvement so that the output torque can be maintained as in the conventional case even if the size is reduced.

[0010]

In order to solve the above-mentioned problems, according to the present invention, an electro-mechanical energy conversion element is fixed between elastic bodies, and driving vibration is applied to the electro-mechanical energy conversion element. In a vibration wave driving device having a vibrating body for exciting bending vibration and a rotor in contact with the vibrating body, the elastic body has a flange-shaped elastic portion extending in a direction orthogonal to the axis of the vibrating body. However, grooves for enlarging vibration displacement are provided on both surfaces in the thickness direction of the flange-shaped elastic portion.

By providing the grooves on both sides in the thickness direction of the flange-shaped elastic portion, the out-of-plane displacement at the outer peripheral portion of the flange-shaped elastic portion can be increased and the output can be increased.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) FIG. 1 shows a sectional view of a vibrating body of a vibration wave driving device according to a first embodiment of the present invention.

A hollow cylindrical first elastic body 1 is made of a material such as brass having a small vibration loss. Reference numeral 2 denotes a flat columnar second elastic body 2, which, like the first elastic body 1, is made of a material having a small vibration damping loss. Four
Is a flange-shaped (disc-shaped) elastic body extending in a direction orthogonal to the axial direction of the vibrating body, and 5 is a shaft.

A threaded portion is provided at one end of the shaft 5, and the second elastic body 2 is screwed into the threaded portion of the shaft 5, whereby the first elastic body 1, the flange-shaped elastic body 4 and the laminated body are laminated. The piezoelectric element 3 is integrally sandwiched and fixed between the flange portion of the shaft 5 and the second elastic body 2.

The flange-shaped elastic body 4 is made of a material having wear resistance, and contacts the rotor (not shown) on the surface near the outer periphery to drive the rotor to rotate. The sliding surface of the flange-shaped elastic body 4 that contacts the rotor is located outside the outer diameters of the first elastic body 1 and the piezoelectric element 3 that are adjacent to each other.

The shaft 5 has its tip fixed to a device (not shown) and acts as a support pin for supporting the vibrating body.
A part of the shaft 5 extending toward the rotor side of the flange-shaped elastic body 4 is formed to be sufficiently thin so that the vibration generated by the vibrating body is absorbed and the vibration propagates to the driven device or the like. It is configured to prevent.

For the sake of convenience, the description will be made with the side having the first elastic body sandwiching the flange-shaped elastic body in the axial direction of the vibrating body as the upper side and the side having the second elastic body as the lower side.

In this embodiment, the diameter of the first elastic body 1 located on the upper side of the flange-shaped elastic body 4 is made smaller, and the diameter of the piezoelectric element 3 and the second elastic body 2 located on the lower side of the elastic body 1 is reduced. The diameter is large. Thus, the upper side of the vibrating body has greater rigidity against bending vibration than the lower side with the flange-shaped elastic body 4 as a boundary, and the dynamic rigidity on both sides with the flange-shaped elastic body 4 as a boundary is significantly different. .

If the outer diameters on both sides in the axial direction with respect to the flange-shaped elastic body 4 are different and have different asymmetrical shapes, for example, when a drive signal is applied to the laminated piezoelectric element 3 in a plane parallel to the paper surface, the vibrating body becomes 2 It is possible to obtain a first-order bending vibration mode of a kind. Specifically, there are a vibration mode in which the lower side of the flange-shaped elastic body 4 is largely deformed and a vibration mode in which the upper side of the flange-shaped elastic body 4 is greatly deformed. That is, even with bending vibrations in the same displacement direction, it is possible to excite two vibration modes in which the relative rates of displacement at both ends of the vibrating body are completely different.

In the vibrating body of this embodiment, the dynamic rigidity on both sides in the axial direction with respect to the flange-shaped elastic body 4 is greatly different, and the displacement due to bending vibration in the vicinity of the flange-shaped elastic body 4 is small. Therefore, by disposing the piezoelectric element 3 in the vicinity of the flange-shaped elastic body, it is possible to suppress the distortion of the piezoelectric element 3 to be small, and it is possible to provide a rod-shaped vibrating body with a small internal loss and a high energy efficiency.

Further, the rotor can be arranged outside the first elastic body 1 to reduce the size of the vibration wave driving device, and if the protruding flange-shaped elastic body 4 is made of metal, the strain is concentrated here. However, since the damping property of the metal material is superior to that of the piezoelectric element, the increase of internal loss is minimized, and a highly efficient short vibrating body can be configured.

However, as described above, such a vibration wave motor tends to have a smaller vibration speed as the size becomes smaller than that of the conventional rod-shaped vibration motor.

Therefore, a concave groove 7 for enlarging vibration displacement is provided on the sliding surface of the flange-shaped elastic body 4 with respect to the rotor and on the surface opposite to the sliding surface. The concave groove 7 provided on the sliding surface side is provided on the inner peripheral side of the sliding portion with the rotor.

FIG. 2 shows a plan view of the flange-shaped elastic body 4 shown in FIG. 1, in which a groove 7 is provided in a circumferential shape concentric with the flange-shaped elastic body. The groove 7 expands the out-of-plane displacement due to the vibration at the outer peripheral portion of the flange-shaped elastic body 4. Although the groove 7 shown in FIG. 2 has a circumferential shape, the shape of the groove is not limited to this, and the shape may be designed in consideration of adjustment of the natural frequency of the vibrating body.

Further, the sliding surface of the vibrating body on which the rotor slides needs to be surface-finished by lapping or the like. By providing the groove 7 on the sliding surface of the flange-shaped elastic body 4, The lapping area can be reduced, and the lapping time can be shortened.

(Second Embodiment) FIG. 3 is a sectional view of a vibrating body of a vibration wave driving device according to a second embodiment of the present invention.

Reference numeral 11 is a first elastic body, 12 is a second elastic body, 13 is a laminated piezoelectric element, and 14 is a flange-shaped elastic body.

The difference from the vibrating body of FIG. 1 is that the vibrating body is configured so as to have a vertically symmetrical shape around the flange-shaped elastic body 14. By configuring the flange-shaped elastic body 14 vertically symmetrically, when a drive signal is applied to the vibrating body, the absolute value distribution of strain generated on both surfaces in the thickness direction of the flange-shaped elastic body 14 becomes symmetrical.

In order to maximize the out-of-plane displacement at the outer peripheral portion of the flange-shaped elastic body 14, the groove 17 is provided in a place where distortion is large when the vibration mode used for driving is excited. In the vibrating body according to the present embodiment, the distortion when the vibration mode used for driving is excited is generated vertically symmetrically,
The grooves 17 are also formed symmetrically on both upper and lower surfaces of the flange-shaped elastic body 14.

The flange-shaped elastic body 14 is provided with a groove 17 having the same shape as the circumferential groove 7 of FIG.

These circumferential grooves 17 play a role of increasing the out-of-plane displacement at the outer peripheral portion of the flange-shaped elastic body 14 and can shorten the lapping time of the flange-shaped elastic body 14. Further, by making both surfaces in the thickness direction of the flange-shaped elastic body 14 symmetrical, there is also an effect of reducing warpage during processing.

(Third Embodiment) FIG. 4 is a sectional view of a vibrating body of a vibration wave driving device according to a third embodiment of the present invention.

Reference numeral 21 is a first elastic body, 22 is a second elastic body, 23 is a laminated piezoelectric element, and 24 is a flange-shaped elastic body. The flange-shaped elastic body 24 has a circumferential groove 27.
Is engraved.

In this embodiment, similarly to the vibrating body shown in FIG. 1, the vibrating body is vertically asymmetrical about the flange-shaped elastic body 24. By configuring the flange-shaped elastic body 24 to be vertically asymmetrical, when a drive signal is applied to the vibrating body, the absolute value distribution of strain generated on both surfaces in the thickness direction of the flange-shaped elastic body 24 becomes asymmetric.

In order to maximize the out-of-plane displacement at the outer peripheral portion of the flange-shaped elastic body 24, the groove 27 is provided in a place where the strain is large when the vibration mode used for driving is excited. In the vibrating body according to the present embodiment, when the vibration mode used for driving is excited, distortion is generated asymmetrically in the vertical direction, and therefore the groove 27 is also formed asymmetrically in both upper and lower sides of the flange-shaped elastic body 24.

These circumferential grooves 27 also play a role of increasing the out-of-plane displacement at the outer peripheral portion of the flange-shaped elastic body 24 and can reduce the lapping time of the flange-shaped elastic body 14.

The vibrating body shown in FIG. 5 is almost the same as the vibrating body of FIG. 1, but is different from the vibrating body of FIG. 1 in that the flange-like elastic body 104 is not provided with a groove for expanding displacement. different. FIG. 6 shows the absolute value distribution of the strain of the flange-shaped elastic body 24 when the vibration mode used for driving the vibrator shown in FIG. 5 is excited.

The distribution of absolute strain values in FIG. 6 is shown between the upper surfaces A and B and between the lower surfaces C and D of the flange-like elastic body 104. As is clear from FIG.
The vibrating body that is formed asymmetrically in the axially upper and lower directions with the flange-shaped elastic body 104 as a boundary is
The areas where the strain is greatest are different between the upper surface and the lower surface. The absolute value distribution of this strain differs depending on the shape of the vibrating body. Therefore, in order to maximize the vibration displacement of the sliding surface of the flange-shaped elastic body, it is desirable to appropriately provide a groove in the portion of the flange-shaped elastic body of each vibration body where the strain is greatest.

(Fourth Embodiment) FIG. 7 shows a fourth embodiment of the present invention.
It is a block diagram of the vibration wave motor concerning embodiment of this.

Reference numeral 31 is a first elastic body, 32 is a second elastic body, 33 is a piezoelectric element, and 34 is a flange-shaped elastic body extending in a direction orthogonal to the axial direction of the vibrating body.

Reference numeral 35 denotes a shaft. The first elastic body 31, the flange-shaped elastic body 34, and the piezoelectric element 33 are sandwiched and fixed between the flange portion provided in the center of the shaft 35 and the second elastic body. ing.

Reference numeral 38 denotes a rotor. A contact spring 38b is joined to the outer circumference of the rotor 38 by adhesion or the like, and a spring case 38a is fitted to the inner circumference. Reference numeral 39 is an output gear, which is fitted and coupled to the spring case 38a so as not to move in the radial direction. Reference numeral 34 is a coil spring for pressurization. A pressurizing spring 34 is arranged between the lower end of the spring case 38b and the output gear 39, and the spring force of this spring 34 causes the spring end of the contact spring 38a fixed to the outer peripheral portion of the rotor 38 to move toward the disk-shaped elastic body 35. Is in pressure contact with the upper surface of. Reference numeral 41 denotes a motor fixing flange, which is sandwiched and fixed by a flange portion of the shaft 35 and a bolt screwed to the shaft 35. The connecting portion between the motor fixing flange 41 and the gear 39 constitutes a sliding bearing. Reference numeral 44 is a flexible substrate for supplying power to the piezoelectric element 33.

The first elastic body 31 has a smaller outer diameter than the second elastic body 32. In this embodiment as well, there are two different types as in the vibrating body shown in FIGS. Bending vibration modes can be excited.

Circumferential grooves 37 are provided on the upper and lower surfaces of the flange-shaped elastic body 34 to expand vibration displacement near the outer periphery of the flange-shaped elastic body 34.

A drive circuit (not shown) is connected to the flexible substrate 44, and the piezoelectric element 33 is connected to the drive circuit.
When an AC electric field having a π / 2 phase difference in time is applied to, the vibrating body excites two bending vibrations in two directions orthogonal to each other. Due to the combination of the vibrations, a circular motion is formed on the upper end surface of the flange-shaped elastic body 34 in contact with the rotor, and the rotor 38 pressed by the flange-shaped elastic body 34 having abrasion resistance is frictionally driven.

[0046]

As described above, according to the present invention, the flange-like elastic body is provided with the grooves on both sides to increase the out-of-plane displacement at the outer peripheral portion, thereby making it possible to reduce the axial size of the vibration wave motor. The output can be increased. In particular, by providing the concave groove at a position where the distortion generated by the vibration mode used for driving is large, it is possible to effectively increase the output.

[Brief description of drawings]

FIG. 1 is a sectional view of a vibrating body of a vibration wave motor according to a first embodiment of the present invention.

FIG. 2 is a top view of the flange-shaped elastic body of FIG.

FIG. 3 is a sectional view of a vibrating body of a vibration wave motor according to a second embodiment of the present invention.

FIG. 4 is a sectional view of a vibrating body of a vibration wave motor according to a third embodiment of the present invention.

FIG. 5 is a sectional view of a vibrating body of a vibration wave motor for explaining distortion.

FIG. 6 is a diagram showing a distortion curve of the vibrator of FIG.

FIG. 7 is a sectional view of a vibration wave motor according to a fourth embodiment of the present invention.

FIG. 8 is a sectional view of a conventional rod-shaped vibration wave motor.

9 is a cross-sectional view of the rod-shaped vibrating body of FIG. 8 and a diagram showing vibration modes.

FIG. 10 is a cross-sectional view of another vibrating body and a diagram showing a vibration mode.

[Explanation of symbols]

1,11,21,31 First elastic body 2, 12, 22, 32 Second elastic body 3,13,23,33 Multilayer piezoelectric element 4,14,24,34 Flanged elastic body 5,35 shaft 6,36 Flexible substrate 7, 17, 27, 37 concave groove 38 rotor 39 gears 40 Coil spring for pressurization 41 Motor fixing flange

Claims (8)

[Claims] 1. An electro-mechanical energy conversion element is provided between a first elastic body and a second elastic body, and a bending vibration is excited by applying a drive signal to the electro-mechanical energy conversion element. In the vibrating body, a flange-shaped elastic portion extending in a direction orthogonal to an axial direction of the vibrating body is provided between the first elastic body and the second elastic body, and a thickness direction of the flange-shaped elastic portion. 2. A vibrating body, characterized in that grooves for enlarging vibration displacement are provided in both sides in the circumferential direction. 2. An electro-mechanical energy conversion element is provided between a first elastic body and a second elastic body, and a bending vibration is excited by applying a drive signal to the electro-mechanical energy conversion element. In the vibrating body, a flange-shaped elastic body extending between the first elastic body and the second elastic body in a direction orthogonal to an axial direction of the vibrating body and having an outer diameter larger than that of the electro-mechanical energy conversion element. And a groove for enlarging vibration displacement in the circumferential direction on both surfaces in the thickness direction of the flange-shaped elastic portion. 3. The vibration wave drive device according to claim 1, wherein the flange-shaped elastic portion is provided with a friction drive portion on an outer peripheral portion thereof. 4. The vibrating body according to claim 3, wherein the groove of the flange-shaped elastic portion is provided on the inner peripheral side of the friction drive portion. 5. The groove of the flange-shaped elastic portion is provided at a location where a large strain is generated when the drive vibration mode is excited in the electro-mechanical energy conversion element. The vibrating body according to any one of 1 to 4. 6. The both surfaces in the thickness direction of the flange-shaped elastic portion have symmetrical shapes.
The vibrating body according to any one of 1 to 4. 7. The vibrating body according to claim 1, wherein both surfaces in the thickness direction of the flange-shaped elastic portion are asymmetrical. 8. A vibrating body according to claim 3, and a contact body that comes into contact with a frictional contact portion of the vibrating body, and a drive signal is applied to the electro-mechanical energy conversion element. A vibration wave driving device is characterized in that a driving wave is formed by bending vibration excited in the vibration body, and the vibration body and the contact body are relatively moved.