JPH10201262A - Vibration actuator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration actuator which can be miniaturized with no complex structure. SOLUTION: A vibration actuator 1 comprises a vibrator 2, a moving piece 14 which, pressurizing/contacting to the vibrator 2, generates a relative motion with the vibrator 2, and a supporting member 10 which supports the vibrator 2 and the moving piece 14. The supporting member 10 comprises an elastic deformation part regarding a pressurizing direction between the vibrator 2 and the moving piece 14 as a supporting pin 12, and the pressurization between the vibrator 2 and the moving piece 14 is performed by an elastic force generated by the supporting pin 12. Thus, no special pressurizing mechanism is required, so the entire length of an ultrasonic actuator 1 is shortened by that amount.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration actuator, and more specifically, to a relative motion for generating a relative motion between a vibrator and a vibrator by contacting the vibrator while being pressed. The present invention relates to a vibration actuator including a member, and a support member that supports a vibrator and a relative motion member.

[0002]

2. Description of the Related Art Vibration actuators have excellent features such as small size, light weight, low speed, and high torque. For this reason, practical use of cameras and the like has been promoted one after another. In recent years, development has been more actively promoted.

FIG. 7 is a longitudinal sectional view showing the structure of an example of the vibration actuator 100. As shown in FIG. The vibration actuator 100 includes a hollow cylindrical vibrator 101 and a vibrator 1.
01 which is in pressure contact with one end face D of the
(Moving element). The vibrator 101 and the relative motion member 102 are both supported by a support shaft 103 penetrating the respective hollow portions. The vibrator 101
Bolts 104a, 10a are attached to the large diameter portion 103a of the support shaft 103.
4b is screwed, and the relative motion member 1
02 is rotatably supported by a support shaft 103 via a bearing 105 and the like.

That is, the vibration actuator 100
In this embodiment, the vibrator 101 includes a hollow cylindrical elastic body 106 and two types of electromechanical transducers (not shown) mounted on the elastic body 106.

[0005] These two types of electromechanical transducers have (π /
2) By applying a driving voltage having a phase difference to each other and utilizing the inverse piezoelectric effect generated in the electromechanical transducer, the vibrator 101 is caused to expand and contract in the axial direction of the vibrator 101 and to vibrate the vibrator 101 Harmonically generates torsional vibration in the axial direction.

Then, on one end face D of the vibrator 101,
An elliptical motion, which is a composite vibration of these vibrations, is generated.
Due to the generated elliptical motion, the relative motion member 102 that comes into pressure contact with the end face D is rotationally driven in one direction.

As described above, the vibration actuator 10
At 0, the elliptical motion generated on the end face D of the vibrator 101 is efficiently and reliably transmitted to the relative motion member 102 via the frictional force. For this purpose, it is effective to control the value of the pressing force between the vibrator 101 and the relative motion member 102 within an appropriate range to adjust the magnitude of the frictional force.

Therefore, in the vibration actuator 100, a disc spring 107 is provided at an end of the support shaft 103 on the side of the relative movement member 102, for example, as a pressing mechanism.
The relative motion member 102 is urged toward the vibrator 101 by utilizing the spring force generated.

The vibration actuator 100
In order to make the most of the feature of “small”, not only the vibrator 101 and the relative motion member 102 but also the pressing mechanism must be downsized. That is, also in the vibration actuator 100 described above, if the disc spring 107 is reduced in size, the overall length of the vibration actuator 100 in the axial direction of the support shaft 103 can be reduced.

For this reason, a disc spring 107 effective for downsizing is used as the pressing mechanism, or the pressing mechanism is used as the relative moving member 10.
2 by incorporating it in a part of the device.

[0011]

However, these techniques reduce the size of the pressurizing mechanism and do not eliminate the pressurizing mechanism, so that there is a limit to the miniaturization that can be achieved.

In order to reduce the size of the pressing mechanism as much as possible, the vibrator 101 and the relative motion member
In addition, it is necessary to devise a design of the O.02, and the vibrator 101 and the relative motion member 102 become complicated, and the degree of freedom in their design is reduced.

An object of the present invention is to provide a vibration actuator which can be reduced in size without complicating the structure.

[0014]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and does not press the relative motion member against the vibrator by providing a dedicated pressurizing mechanism. The above object is achieved by partially providing such a pressurizing function and eliminating the dedicated pressurizing mechanism.

According to a first aspect of the present invention, there is provided a vibrator for generating vibration, a relative motion member for generating relative motion between the vibrator and the vibrator in contact with the vibrator under pressure, A vibration actuator comprising: a support member that supports a motion member, wherein the support member includes an elastic deformation portion in a pressing direction between the vibrator and the relative motion member, and the support member includes: Is performed by the elastic force generated by the elastic deformation portion.

According to a second aspect of the present invention, in the vibration actuator according to the first aspect, the rigidity of the elastic deformation portion in the pressing direction is lower than the rigidity in a direction other than the pressing direction. .

The third aspect of the present invention is the first or second aspect.
Wherein the support member is a support shaft disposed so as to penetrate the vibrator and the relative motion member, or a housing that encloses the vibrator and the relative motion member. .

According to a fourth aspect of the present invention, in the vibration actuator according to the third aspect, when the support member is a support shaft, the elastically deformable portion is provided with a notch provided on the support shaft, and / or , A vibrator and a support pin penetrating the support shaft.

According to a fifth aspect of the present invention, in the vibration actuator according to the fourth aspect, a counterbore is provided in a portion of the support shaft where the support pin penetrates.

The invention of claim 6 is the invention of claims 1 to 5
In the vibration actuator described in any one of the above items, the vibrator has a columnar outer shape and generates elastic vibration in the axial direction and torsional vibration in the axial direction.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION

(First Embodiment) Hereinafter, an embodiment of a vibration actuator according to the present invention will be described in detail with reference to the accompanying drawings. In the following description of the embodiments, an example of an ultrasonic actuator that uses an ultrasonic vibration region as a vibration actuator will be described.

FIG. 1 is a longitudinal sectional view showing the structure of the ultrasonic actuator 1 according to the first embodiment. Vibrator 2
Is that the piezoelectric member 3 which is an electromechanical transducer that is excited by a drive signal, and the piezoelectric member 3 is joined to generate primary longitudinal vibration and secondary torsional vibration by excitation of the piezoelectric member 3. And the elastic body 4 that generates a driving force on the driving surface D of the vibrator 2.

As shown in FIG. 1, the elastic body 4 has three small-diameter portions 4a, 4b and 4c formed on its side surface and four large-diameter portions 4a to 4c formed by being divided into three small-diameter portions 4a to 4c. It has diameter portions 4A, 4B, 4C and 4D.

The elastic body 4 is divided into two semi-elastic bodies 5a and 5b along the height direction by a vertical surface including a substantially central axis, and the piezoelectric body 3 is provided on each of these two divided surfaces. Hold in the sandwiched state.

The piezoelectric body 3 is composed of a two-layer longitudinal vibration piezoelectric body 3a and a torsional vibration piezoelectric body 3b. Longitudinal vibration piezoelectric element 3a is made of a piezoelectric material using a piezoelectric constant d _31, it is provided at a position (one point), including the section of the primary longitudinal vibration generated in the elastic body 4. On the other hand, torsional vibration piezoelectric member 3b is made of a piezoelectric material using a piezoelectric constant d _15, including the section position of the drive surface D side of the nodal positions of the secondary of torsional vibration generated in the elastic body 4 It is provided at a position (one place).

At the substantially central portion in the longitudinal direction of the vibrator 2 of each of the large diameter portions 4A to 4D of the elastic member 4, through holes 6a to 6d are provided in a direction parallel to the laminating direction of the piezoelectric members 3. The two semi-elastic bodies 5a and 5b are formed with these through holes 6a.
Insert bolts 7a to 7d into nuts 8a to 8d
Is fixed while sandwiching the piezoelectric bodies 3a and 3b.

The small diameter portion 4b of the elastic body 4 has through holes 6a
A through hole 9 is provided in a direction parallel to the forming direction of 6d. The support shaft 10 penetrates through a hollow portion formed in the center of the vibrator 2 in the longitudinal direction of the vibrator 2 with a gap from the inner surface of the vibrator 2. At a substantially central portion in the longitudinal direction of the support shaft 10,
A through hole 11 having the same inner diameter as the through hole 9 is provided. The vibrator 2 is fixed and held on the support shaft 10 by fitting the support pins 12 fitted into the through holes 9 and 11. The support shaft 10 is provided with through holes 13a to 13d through which the bolts 7a to 7d pass.

That is, the semi-elastic bodies 5a and 5b are held in a state where the support shaft 10 is sandwiched at a predetermined position, and the longitudinal vibration piezoelectric bodies 3a and 5b are held.
With the torsion vibration piezoelectric body 3b interposed between the divided surfaces, bolts 7a
7d and nuts 8a to 8d, and then fixed by mounting the support pin 12.

The portions 12a and 12b of the support pin 12 located between the vibrator 2 and the support shaft 10 are elastically deformed when an external force acts on the vibrator 2 in the longitudinal direction of the support shaft 10. Bend. That is, in the present embodiment, the support pin 12 forms an elastic deformation portion that supports the vibrator 2 and elastically deforms in the pressing direction between the vibrator 2 and the moving element 14.

A moving element 1 which makes a relative motion with a vibrator 2
Reference numeral 4 denotes a thick circular annular moving child base material 14a and a moving child base material 1
An annular sliding member 14b is attached to the end face of the vibrator 2 on the side of the vibrator 2 and contacts the driving surface D of the vibrator 2.

A bearing 16 is mounted on the inner edge 15 of the end face of the movable element base material 14a on the side opposite to the oscillator. This bearing 16 is mounted on the support shaft 10. This allows
The mover 14 is rotatably supported by the support shaft 10.

The end of the support shaft 10 and the bearing 1
6 is formed with a threaded portion 10 a at a portion exposed from the mounting portion, and the nut 17 is brought into contact with the bearing 16.
Is screwed to the screw portion 10a, so that the movable element 14
Are positioned in the longitudinal direction of the support shaft 10 and the vibrator 2
Is brought into pressure contact with the drive surface D.

As described above, in the ultrasonic actuator 1 of the present embodiment, the pressure between the vibrator 2 and the moving element 14 is
This is performed by the elastic force generated by the support pin 12 which is an elastic deformation portion.

As described with reference to FIG. 1, in the ultrasonic actuator 1 of the present embodiment, the moving element 14 is
There is no dedicated pressurizing mechanism for making pressurized contact toward. Therefore, the total length in the longitudinal direction of the vibrator 2 is
This can be reduced compared to the conventional ultrasonic actuator shown in FIG.

FIG. 2 is an explanatory diagram showing the structure of the vibrator 2 used in the ultrasonic actuator 1 of the present embodiment.
2A is a side view showing a cross section of the left half from the center line of the vibrator 2, and FIG. 2B is a cross section taken along the line AA, BB, and CC in FIG. 2A. is there.

As shown in FIG. 2A, the elastic member 4 is a semi-elastic member 5a, 5b obtained by vertically dividing a hollow cylindrical elastic member into two.
Are held in a state where the piezoelectric bodies 3a and 3b are sandwiched between the divided surfaces. The piezoelectric bodies 3a and 3b are composed of two groups, and each group is composed of two layers of piezoelectric bodies.

As described above, one of the two groups of piezoelectric bodies
Group, piezoelectric 3a is used to use a piezoelectric constant d ₃₁ at a position including a node position of the first-order longitudinal vibration generated in the elastic body 4.
On the other hand, the remaining one group has a piezoelectric constant d ₁₅ at the end face on the drive surface D side among the positions including the nodal position of the secondary torsional vibration.
Is used.

In the present embodiment, a reinforcing member 18 having the same thickness as the piezoelectric bodies 3a and 3b is provided on the side of the position including the nodal position of the secondary torsional vibration opposite to the drive surface D. Be attached. The reinforcing member 18 prevents a gap from being generated inside the elastic body 4, and prevents adverse effects on vibration generation and propagation.

The piezoelectric body 3 b using the piezoelectric constant d ₁₅ generates a shear displacement in the longitudinal direction of the elastic body 4. FIG.
The four piezoelectric bodies 3b in the AA cross section of (b) are arranged such that the circumferentially shearing deformation of the elastic body 4 alternates in the front direction and the opposite direction. When the four piezoelectric members 3b are arranged as described above and each of the piezoelectric members 3b is sheared, a secondary torsional displacement occurs in the vibrator 2.

The piezoelectric 3a using latter piezoelectric constant d ₃₁
Causes expansion and contraction displacement in the longitudinal direction of the elastic body 4.
The four longitudinal vibration piezoelectric bodies 3a in the BB cross section of FIG. 2B are arranged so that when a certain potential is applied, all of them extend and contract in the same direction.

[0041] As described above, the torsional vibration piezoelectric member 3b using a piezoelectric constant d _15, when arranging the piezoelectric d ₃₁ for longitudinal vibration using a piezoelectric constant d _31, the torsional vibration piezoelectric member 3b , A torsional motion is generated in the vibrator 2 accordingly. On the other hand, the piezoelectric body 3 for longitudinal vibration
When a sine wave voltage is input to a, the vibrator 2 expands and contracts accordingly.

As shown in FIG. 2B, the driving circuit 20
Is a oscillating unit 21 for oscillating the drive signal, a phase shift unit 22 for distributing the oscillated drive signal to a signal having a (１ ／) λ phase difference, and a drive signal to be input to the torsional vibration piezoelectric body 3b. And an L amplifying unit 24 that amplifies the drive signal input to the longitudinal vibration piezoelectric body 3a.

In the ultrasonic actuator 1, the oscillation section 21
Oscillates a drive signal, and the oscillated drive signal is
, The signal is divided into two signals having a (４) λ phase difference, and are amplified by the T amplifier 23 and the L amplifier 24, respectively.

The drive signal amplified by the T amplifier 23 is input to the four torsional vibration piezoelectric bodies 3b. On the other hand, the drive signal amplified by the L amplifying unit 24 is input to the four longitudinal vibration piezoelectric bodies 3a.

When a drive signal is applied to the vibrator 2 from each of the T amplifying unit 23 and the L amplifying unit 24, the vibrator 2 is excited by the longitudinal vibration piezoelectric body 3a and the torsional vibration piezoelectric body 3b. A first-order longitudinal vibration and a second-order torsional vibration are generated.

FIG. 3 is an explanatory diagram showing an example of a longitudinal vibration and a torsional vibration generated in the vibrator 2. When a drive signal is applied to the vibrator 2, the vibrator 2 has a primary longitudinal vibration (L1 mode) and a secondary torsional vibration (L1 mode) having antinodes and nodes of vibration as shown in FIG. T2 mode). At this time, in the torsional vibration, nodes exist in the first small-diameter portion 4a and the third small-diameter portion 4c having low torsional rigidity, and the drive surface D is located at the antinode position. On the other hand, in the longitudinal vibration, a node exists in the second small diameter portion 4b, and the driving surface D is located at the antinode position.

At this time, if the phase difference between the periodic voltages applied to the torsional vibration piezoelectric body 3b and the longitudinal vibration piezoelectric body 3a is set to be shifted by (１ ／) λ, the driving surface D of the vibrator 2 is set. Generates an elliptical motion that is a combined vibration of the longitudinal vibration and the torsional vibration.

FIG. 4 is an explanatory diagram showing the occurrence of the elliptical motion on the driving surface D of the vibrator 2 with the lapse of time. Note that, in FIG. 4, the moving element 14 that comes into pressure contact with the driving surface D is omitted for convenience of description.

As shown in FIG. 4, assuming that the angular frequency is ω, the displacement of the torsional vibration T is maximum on the left side at t = (6/4) · (π / ω), while The displacement of the longitudinal vibration L is zero. In this state, the moving element comes into pressure contact with the driving surface D of the vibrator 2 by the elastic force of the support shaft 10.

From this state, t = (7/4) · (π /
ω) to 0 to (2/4) · (π / ω), the torsional vibration T is displaced from the maximum on the left to the maximum on the right, while the longitudinal vibration L is increased from zero to the maximum on the upper side. It displaces and returns to zero again. Therefore, the fixed point of the driving surface D of the vibrator 2 rotates rightward while pressing the moving element, and the moving element is driven.

Next, t = (2/4) · (π / ω)-(6
/ 4) · (π / ω), the torsional vibration T is displaced from the right maximum to the left maximum, while the longitudinal vibration L is displaced from zero to a lower maximum and returns to zero again. . Therefore, the fixed point of the driving surface D of the vibrator 2 rotates leftward while leaving the movable element, and the movable element is not driven. At this time, even if the movable element is pressurized by the elastic force of the support shaft 10, it does not follow the contraction of the oscillator 2 because the natural frequency is different.

The frequency of the torsional vibration is made substantially equal to the resonance frequency of the torsional vibration, and the frequency of the longitudinal vibration is made substantially equal to the resonance frequency of the longitudinal vibration. The elliptical motion generated on the drive surface D is enlarged.

In the ultrasonic actuator 1 of this embodiment, the resonance frequency of the generated longitudinal vibration and the resonance frequency of the torsional vibration can be made substantially the same by the vibrator 2 alone. That is, in the ultrasonic actuator 1 according to the present embodiment, since the torsional resonance frequency and the longitudinal resonance frequency can be both determined by the vibrator 2 alone, the shape of the movable element 14 can be freely set. .

As described in detail above, in the ultrasonic actuator 1 of the present embodiment, the vibrator 2 is connected to the support pin 12.
, So as to be displaceably supported with respect to the support shaft 10 via the support member, so that it is not necessary to provide a dedicated pressurizing mechanism for pressing the vibrator 2 against the moving member 14. Therefore,
Since there is no need to provide a dedicated pressurizing mechanism, the overall length of the ultrasonic actuator 1 in the pressurizing direction can be reduced.

That is, according to the ultrasonic actuator 1 of the present embodiment, it is possible to reliably press the moving element 14 toward the vibrator 2 while reducing the size of the ultrasonic actuator 1.

(Second Embodiment) Hereinafter, a second embodiment of the present invention will be described in detail with reference to the accompanying drawings. In addition,
In the following description of each embodiment, only portions different from the first embodiment will be described, and common portions will be denoted by the same reference numerals in the drawings, and redundant description will be omitted.

FIG. 5 is an enlarged longitudinal sectional view showing the vicinity of the penetrating portion of the support pin 12 in the ultrasonic actuator 1-1 of this embodiment. As shown in FIG. 5, an elastically deformable portion is constituted by the support pin 12 as in the first embodiment, but in the present embodiment, the support pin 1 of the support shaft 10 is further provided.
A counterbore hole is provided in the second penetrating portion to form a small diameter portion 10b.

By forming the small diameter portion 10b, the amount of elastic deformation of the support pin 12 can be increased, so that the set width of the pressing force between the vibrator 2 and the moving element 14 can be increased. Become.

(Third Embodiment) FIG. 6 is an enlarged longitudinal sectional view showing the vicinity of a support portion of a vibrator 2 in an ultrasonic actuator 1-2 according to a third embodiment.

The ultrasonic actuator 1-2 of the present embodiment
Unlike the first embodiment and the second embodiment, the support pin 12 is not used for fixing the vibrator 2 to the support shaft 10, and like the conventional ultrasonic actuator 100 shown in FIG.
Bolts 104a and 104b are used. Further, the large-diameter portion 10c is provided substantially at the center of the vibrator 10 in the longitudinal direction, similarly to the ultrasonic actuator 100.

In this embodiment, the bolt 10 of the support shaft 10
Notches 10d and 10e are provided between the penetrating portions 4a and 104b and the vibrator driving surface D by appropriate means. In the present embodiment, the portions provided with the notches 10d and 10e function as elastic deformation portions.

By forming these notches 10d and 10e, the pressing direction (the supporting shaft 1
The rigidity of the elastically deformable portion with respect to the longitudinal direction (0) is lower than the rigidity in directions other than the pressing direction. Thus, the support shaft 10 can be elastically deformed (expanded and contracted) in the longitudinal direction in a portion above the bolt 104a, 104b penetrating portion.

That is, according to the present embodiment, the support shaft 1
Although the positional relationship between the zero bolting position and the vibrator 2 is fixed, the relationship between the movable member 14 rotatably supported on the elastically deformable support shaft 10 and the bolting position of the support shaft 10 is variable. Becomes

Thus, the moving element 14 comes into pressure contact with the vibrator 2 with a suitable pressing force. Therefore, also in this embodiment, since the elastic deformation portion is provided in a part of the support shaft 10, a dedicated pressurizing mechanism is not required.

(Modification) In the description of each embodiment, the ultrasonic actuator is used. However, the vibration actuator according to the present invention is not limited to such an embodiment, and the vibration actuator using another vibration region is used. Is equally applicable.

Further, in the description of each embodiment, the piezoelectric body is used as the electromechanical transducer, but the vibration actuator according to the present invention is not limited to such a mode, and the electric energy is converted into the mechanical displacement. Anything that can be converted can be applied equally. For example, an electrostrictive element other than the piezoelectric body can be exemplified.

Further, in the description of each embodiment, the vibration actuator in which the vibrator and the moving element are supported by the support shaft penetrating the central portion is taken as an example, but the vibration actuator according to the present invention has such a mode. It is not limited.

For example, the vibrator is fixed and accommodated in a housing (casing) that encloses the vibrator and the moving element that comes into pressure contact.
The present invention can be equally applied to a vibration actuator that supports and rotatably supports a moving element. In this case, an elastic deformation portion may be formed between the vibrator support portion and the mover support portion of the casing by an appropriate means.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view illustrating a configuration of an ultrasonic actuator according to a first embodiment.

FIG. 2 is an explanatory diagram illustrating a configuration of a vibrator used in the ultrasonic actuator according to the first embodiment, and FIG. 2A is a side view illustrating a cross section of a left half of a center line of the vibrator. 2
(B) is an AA section, a BB section, and a CC section in FIG.

FIG. 3 is an explanatory diagram illustrating an example of longitudinal vibration and torsional vibration generated in a vibrator in the ultrasonic actuator according to the first embodiment.

FIG. 4 is an explanatory diagram showing, over time, occurrence of elliptical motion on a driving surface of a vibrator in the ultrasonic actuator according to the first embodiment.

FIG. 5 is an enlarged longitudinal sectional view showing the vicinity of a through portion of a support pin in an ultrasonic actuator according to a second embodiment.

FIG. 6 is an enlarged longitudinal sectional view showing the vicinity of a support portion of a vibrator in an ultrasonic actuator according to a third embodiment.

FIG. 7 is a longitudinal sectional view showing a configuration of a conventional vibration actuator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ultrasonic actuator 2 Vibrator 3 Piezoelectric body 3a Piezoelectric body for longitudinal vibration 3b Piezoelectric body for torsional vibration 4 Elastic body 4a-4c Small diameter part 4A-4D Large diameter part 5a, 5b Semi-elastic body 6a-6d Through hole 7a To 7d bolt 8a to 8d nut 9 through hole 10 support shaft 10a screw part 11 through hole 12 support pin 13a to 13d through hole 14 mover 16 bearing 17 nut 18 reinforcing material 20 drive circuit 21 oscillation part 22 phase shift part 23T amplification Unit 24 L amplification unit

Claims (6)

[Claims] 1. A vibrator for generating vibration, a relative motion member for generating relative motion between the vibrator and the vibrator in contact with the vibrator under pressure, the vibrator and the relative motion A vibration actuator comprising: a support member that supports a member; wherein the support member includes an elastic deformation portion in a pressing direction between the vibrator and the relative motion member; The vibration actuator is characterized in that the pressurization between the member and the member is performed by an elastic force generated by the elastic deformation portion. 2. The vibration actuator according to claim 1, wherein a rigidity of the elastic deformation portion in the pressing direction is lower than a rigidity in a direction other than the pressing direction. 3. The vibration actuator according to claim 1, wherein the support member is a support shaft disposed so as to penetrate the vibrator and the relative motion member, or the vibrator and the support shaft. A vibration actuator, which is a container enclosing the relative motion member. 4. The vibration actuator according to claim 3, wherein, when the support member is the support shaft, the elastically deformable portion includes a notch provided on the support shaft, and / or A vibration actuator, comprising: the vibrator and a support pin penetrating the support shaft. 5. The vibration actuator according to claim 4, wherein a counterbore hole is provided in a portion of the support shaft through which the support pin penetrates. 6. Any one of claims 1 to 5
In the vibration actuator described in the paragraph, the vibrator has a columnar outer shape and generates elastic vibration in the axial direction and torsional vibration in the axial direction.