JP2019180175A - Linear type actuator - Google Patents

Abstract

To provide a linear type actuator capable of achieving a stable pressure force with a simple structure as well as achieving a stable driving force even in the case where a moving distance of a movable body (oscillation unit) is long, and suppressing the generation of an abnormal noise without transmitting a residual oscillation which does not apply a direct influence on the driving force to the other member.SOLUTION: A linear type actuator 10 containing an oscillator 12 formed by a lamination structured piezo electric element that generates a composite vibration of a telescopic oscillation and a bend oscillation, and having a movable body capable of performing a reciprocating-motion in one direction, comprises: a pressure application member 13 that applies a pressure while contacting one end part of the oscillator to a slide member 52; an oscillation unit 11 that functions as the movable body that is installed in a housing 16 and performs the reciprocating-motion in a horizontal surface while having at least the oscillator; and bearings 53 to 55 contacted to a lower surface 52d opposite to a surface to which the oscillator of the slide member is contacted.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a linear actuator in which a plurality of piezoelectric elements are stacked.

The linear actuator generates one specific ultrasonic vibration or two different specific ultrasonic vibrations at a predetermined frequency and timing in the vibration body, so that a rotational motion such as an ellipse or the like is generated in the vibration output portion of the vibration body. A reciprocating motion is generated, and this motion is transmitted to a driven body such as a rotor that is brought into contact with the vibration output section to drive the driven body. This linear actuator can realize low speed and high torque, is excellent in quietness, and is suitable for reduction in size and weight. For this reason, it is widely used as a drive source for various movable mechanisms that require precise positioning, such as a camera autofocus function and a scanning electron microscope.
By the way, in such a linear actuator, a laminated piezoelectric element is mainly used as a vibrating body. According to this laminated piezoelectric element, it is known that, for example, when compared with a single plate-like piezoelectric body having the same thickness, a larger deformation strain and generating force can be obtained with a low applied voltage.

  For example, in Patent Document 1, three guide portions that guide a rolling member are provided in a moving member that moves together with the vibrator, and the rolling members accommodated in the three guide portions are within a triangle that connects with a straight line. A linear ultrasonic motor that avoids an increase in the overall length of the unit without lowering the output and driving efficiency by positioning the pressing center of the vibrator to be pressed is disclosed.

  Patent Document 2 discloses a moving body supported by a shaft, an actuator that contacts the moving body, a roller that contacts the moving body at a position facing the actuator, and an elastic force that biases the actuator and the roller to the moving body. A linear ultrasonic motor capable of absorbing a displacement in the biasing direction due to the shape error and mounting error of the actuator and efficiently transmitting the driving force from the actuator to the moving body. Is disclosed.

Japanese Patent Laying-Open No. 2015-65809 JP 2012-39848 A

  By the way, in a linear actuator, it is necessary that a stable drive output can be obtained even if the moving body moves, and that a stable driving force can be obtained regardless of the moving position even at a position where the moving body has moved. It is.

However, in Patent Document 1, a guide portion that defines the maximum amount of movement of the moving vibrator is formed on the moving plate and the cover plate, and the vibrating member is sandwiched between the moving plate and the cover plate, thereby It is movable. However, since the end of the cover plate forming the rolling element guide portion is screwed to the base plate, the center portion of the cover plate forming the guide portion is bent, resulting in stable driving. It has the disadvantage that power cannot be obtained. In particular, as the amount of movement of the vibrator in the direction of the guide portion is increased, the guide portion is bent more, and a more stable driving force cannot be obtained.
In addition, since the spring for pressurizing the vibrator is supported by using a plurality of members, it is difficult to apply a stable pressing force as the movement amount of the vibrator increases, and a stable driving force and vibrator It has the disadvantage that it is difficult to obtain the moving speed.

  In Patent Document 2, the shaft that supports the moving body is restricted only in the height direction by a roller on the upper surface of the moving body and two vibrators from the lower surface of the moving body, and the restriction in the shaft rotation direction is an elastic body. Therefore, the shaft is easy to rotate, the contact between the vibrator and the moving body becomes uneven, and the driving force becomes unstable. Further, the instability of the driving force has a drawback that it becomes more prominent as the moving distance of the moving body becomes longer.

  According to the present invention, a stable driving force can be realized even when the moving distance of the moving body is long, and at the same time, a stable pressing force can be realized with a simple structure, and an extra vibration that does not directly affect the driving force. It is an object of the present invention to provide a linear actuator that can also suppress the generation of abnormal noise without propagating to other members.

The present invention includes the following.
[1] A linear actuator including a vibrator including a piezoelectric element having a laminated structure that generates a combined vibration of stretching vibration and bending vibration, and having a moving body that can reciprocate only in one direction. A pressurizing member that contacts and pressurizes the sliding member; a vibration unit that includes at least the vibrator; is installed on a support member and reciprocates in a horizontal plane; and the vibrator of the sliding member And a rolling member that contacts a surface that faces the surface that contacts the linear actuator.
[2] The rolling member is attached to a support member on which the vibration unit is installed, and a convex portion or a concave portion is formed on a surface of the sliding member in contact with the rolling member. At least one is arranged in the direction orthogonal to the moving direction of the vibration unit and on one side of the convex portion or the concave portion of the sliding member, and the total number of the rolling members is three. Linear actuator.
[3] The linear actuator according to [1] or [2], wherein the support member includes a first member on which the rolling member is disposed and a plurality of second members to which the vibration unit is attached.
[4] The vibrator according to any one of [1] to [3], wherein the vibrator constituting at least a part of the vibration unit includes an elastic member disposed so as to surround at least two nodes of bending vibration. Linear actuator.
[5] When the length of the vibrator is L and the width is W, the following expression (1) is satisfied. 0.21 <W / L <0.26 (1)
The linear actuator according to any one of [1] to [4].

  According to the present invention, by adopting a structure in which the vibration unit including the vibrator is installed on the support member and the sliding member is sandwiched between the vibration unit and the three rolling members, the movable body (vibration) Stable driving force can be realized even when the unit is moved long, and at the same time, stable pressing force can be realized with a simple structure, and extra vibration that does not directly affect the driving force is propagated to other members. Thus, it is possible to provide a linear actuator that can also suppress the generation of abnormal noise.

BRIEF DESCRIPTION OF THE DRAWINGS It is a linear type actuator by this invention, (a) is a front view, (b) is a top view, (c) is Ic-Ic sectional drawing of (a). The disassembled perspective view of the linear type actuator by this invention. The exploded view of vibrator ASSY. The electrode shape pattern figure of a piezoelectric element. It is a vibration expansion / contraction vibration explanatory drawing, (a) Initial state, (b) At expansion, (c) At contraction. It is an oscillator bending vibration explanatory view, (a) initial state, (b) at the time of bending (at the time of forward rotation), (c) at the time of bending (at the time of inversion). The figure which shows one Example of the structure of a housing (support member). The figure which shows the other Example of the structure of a housing (support member).

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. 1-7 is a figure which shows an example of the linear actuator which concerns on one Embodiment of this invention.

  1 and 2, the linear actuator 10 includes a vibration unit 11 (moving body) and a sliding member (fixed) 52, and the vibrator 12 mounted on the vibration unit 11 expands and contracts. The vibration unit 11 reciprocates linearly with respect to the sliding member 52 by bending vibration.

  As shown in FIG. 2, the vibration unit 11 includes a vibrator 12, a pressure member 13, a tension spring 14, and a housing (support member) 16.

  Hereinafter, <<< entire mechanism system >>, <<< layered vibrator>, <<< piezoelectric element wiring pattern constituting the vibrator >>, << width (W) / length (L) ratio of the stacked vibrator It demonstrates in order of >>.

<< Overall mechanical system >>
The entire mechanism system will be described below.
First, as shown in FIGS. 3 and 6, the vibrator 12 is supported by the elastic member 35 so as to surround the bending vibration node 12 e, and further supported by the holding member 32 to move in the longitudinal direction within the housing 16. It is supported freely. The pressurizing member 13 is formed in a rod shape and applies a pressing force to the vibrator 12 by a tension spring 14 installed at both ends 13a and 13b.

  The housing 16 shown in FIGS. 1 and 2 is formed with slide grooves 16d on both wall surface portions 16s for accommodating protrusions 32p of a holding member 32 for holding a vibrator ASSY 31 described later so as to be movable in the vertical direction. Further, the housing 16 includes a top surface portion that accommodates the pressing member 13 and a groove 16e. The housing 16 includes a base portion 16b, and the base portion 16b has bearing portions 65 and 66 to which shafts (shafts) for mounting the bearings 53 to 55 are attached. The housing 16 is integrally formed in a desired size and shape by, for example, injection molding of molten resin.

Further, the pressing member 13 has a spherical protrusion 13 p formed at a portion facing the upper end surface 12 u of the vibrator 12. (See FIGS. 1A and 1C.)
Thus, even when the vibrator 12 is slightly inclined, the pressing force by the tension spring 14 can be appropriately transmitted to the contact 19 by the spherical protrusion 13p of the pressing member 13, and the driving efficiency is good. A linear actuator can be realized.

  By the way, as shown in FIGS. 1 and 2, the sliding member 52 has the upper surface 52 u brought into contact with the contact 19 of the vibrator 12 of the vibrator ASSY 31 to synthesize the stretching vibration and bending vibration of the vibrator 12. Due to the elliptical vibration, the vibration unit 11 reciprocates linearly. As shown in FIG. 1, the bearing 54 is disposed on one side surface of the sliding member convex portion 52 a and the bearings 53 and 55 are disposed on the other side, and the contact 19 is brought into contact with the upper surface 52 u of the sliding member 52. Thus, the structure in which the sliding member 52 is supported in the vertical direction of FIG. 1 is adopted.

  As will be described later, in the bearings 53 to 55 arranged on the lower surface 52d side of the sliding member 52, a straight line connecting the centers of the three bearings 53 to 55 forms a triangle, and contacts within this triangular region. It arrange | positions so that the child 19 may exist.

  Further, as shown in FIG. 1B, the bearing 54 is disposed so as to be positioned at the center of the bearings 53 and 55 on both ends. That is, the three bearings 53 to 55 are arranged at the respective apexes of the triangle.

  These bearings 53 to 55 are arranged on both sides of the sliding member convex portion 52 a extending in the longitudinal direction of the sliding member 52, thereby suppressing the inclination and rotation of the vibration unit 11 and causing elliptical vibration by the vibrator 12. It can be stably transmitted to the sliding member 52. In addition, the sliding member convex part 52a is not limited to a convex part, Of course, even if it is the recessed part extended in the sliding member 52 longitudinal direction, the effect similar to a convex part is acquired. is there.

By the way, as the sliding member 52, any material may be used as long as it has high strength and excellent slidability as represented by alumina (Al ₂ O ₃ ) ceramics. Furthermore, the bearing which is a rolling member may be, for example, a resin roller type containing a sliding material as well as a metal.

  Further, even if the sliding member 52 is lengthened and the moving distance of the vibration unit 11 is increased, the three bearings 53 to 55 arranged in the horizontal plane move together, so that the inclination of the vibration unit 11 Rotation can be suppressed and a stable drive output can be obtained.

<< Stacked vibrator >>
Hereinafter, the laminated vibrator will be described.
Incidentally, as shown in FIG. 3, the vibrator 12 is formed in a laminated structure in which rectangular piezoelectric elements 12 </ b> P are stacked in a prismatic shape, and is held in the holding member 32. This vibrator 12 compresses and deforms a part of the elastic member 35 so that the elastic member 35 formed in a rectangular frame shape is positioned around the node 12e of the vibrator 12 as shown in FIG. Further, the elastic member 35 is held by being compressed and deformed between the holding ribs 32r (concave portions) of the holding member 32.

Further, the laminated vibrator 12 is formed by laminating a plurality of piezoelectric materials made of lead zirconate titanate (PZT, Vickers hardness 350 to 380) having a thickness of 50 to 200 μm. As the piezoelectric material, lead zirconate titanate having a mechanical quality factor of 1000 or more is preferable.
Here, the mechanical quality factor is a numerical value that represents a loss factor due to vibration, and is precisely the reciprocal of the elastic loss factor. Therefore, a material having a large mechanical quality factor has a small elastic loss factor, and the material itself has a small internal loss, so that a good vibration can be generated.

The elastic member 35 is made of a rubber material such as silicone rubber or ethylene / propylene rubber (EPT, EPDM). In particular, the rubber material used here is effective in suppressing the generation of abnormal noise so that extra vibration other than the vibration of the vibrator 12 that directly contributes to the driving force is not transmitted to the holding member 32 and the case 33. For this purpose, it has been experimentally found that the loss coefficient (tan δ) must be a certain value or less as a rubber material.
Specifically, the silicone rubber or ethylene / propylene rubber described in Table 1 was excellent. Furthermore, in order to obtain a driving force, an externally applied voltage is continuously applied to the vibrator 12 to cause minute vibrations, and thus the temperature of the vibrator 12 itself is inevitably increased. Therefore, it was found that the rubber material also needs to have a certain level of heat resistance. The results are shown in <Table 1>. As can be seen from this table, from the viewpoint of heat resistance, the heat resistance temperature of ethylene propylene rubber or higher was necessary.

なお、損失係数の測定は、基本的には、ＪＩＳ Ｋ６３９４準拠して測定をおこなった。具体的測定方法を以下に記載する。
＜損失係数（ｔａｎδ）測定方法＞
・測定器：上島製作所製 粘弾性アナライザＹＲ−７１３０
・測定温度：室温
・変形方法：引張
・周波数：１００Ｈｚ
・振幅：±１％
・プレロード：４８０ｍＮ
・試験片形状：２０ｍｍ（つかみ間隔）×４ｍｍ（幅）×２ｍｍ（厚さ））の短冊形状片
また、＜表１＞における総合評価とは損失係数、耐熱温度、耐オゾン性、電気絶縁性をすべて満足するものを「○（丸）」、一つでも満足しない項目がある場合には「×（バツ）」とした。以上の結果から、弾性部材３５として使用可能なゴム（熱硬化性エラストマ）は、損失係数（ｔａｎδ）が０．１５以上で、かつ耐熱温度が１５０℃以上の物性値を有することが必要であることが判明した。 <Table 1>

The loss factor was basically measured in accordance with JIS K6394. A specific measurement method is described below.
<Method of measuring loss factor (tan δ)>
-Measuring instrument: Viscoelastic analyzer YR-7130 manufactured by Ueshima Seisakusho
・ Measurement temperature: Room temperature ・ Deformation method: Tensile ・ Frequency: 100 Hz
・ Amplitude: ± 1%
・ Preload: 480mN
-Test piece shape: strip shape piece of 20 mm (grip interval) x 4 mm (width) x 2 mm (thickness)) Also, the comprehensive evaluation in <Table 1> is loss coefficient, heat resistance temperature, ozone resistance, electrical insulation “○ (circle)” indicates that all of the items are satisfied, and “× (x)” indicates that there is an item that does not satisfy even one item. From the above results, the rubber (thermosetting elastomer) that can be used as the elastic member 35 is required to have a physical property value such that the loss coefficient (tan δ) is 0.15 or more and the heat-resistant temperature is 150 ° C. or more. It has been found.

Hereinafter, the reason why the elastic member 35 is arranged so as to cover the outer periphery of the vibrator 12 including the bending vibration node 12e of the vibrator 12 will be described in detail.
When the vibrator 12 performs bending vibration and expansion / contraction motion, a node having a small displacement of the vibrator 12 is formed (12e and 12m in FIGS. 5 and 6). And in the area | region except a node part, the abdominal part which the vibrator | oscillator 12 displaces greatly by bending vibration and expansion-contraction movement is formed.

  For this reason, in the vibrator 12, an elastic member 35 is attached to the outer periphery of the bending vibration node (12 e) of the vibrator 12 for the purpose of holding a place where the displacement of the vibrator 12 is small, and the holding rib of the holding member 32. It is compressed and held between 32r (concave portion). That is, the elastic member 35 has a uniform width (thickness) in the length (L) direction of the vibrator 12 around the bending vibration node (12e) of the vibrator 12. The length (= thickness) of the elastic member 35 in the length direction of the vibrator 12 is greater than 0.5 mm and less than 1.5 mm. The reason for this numerical range is that when the thickness of the elastic member 35 is 0.5 mm or less, the posture of the vibrator 12 cannot be kept good, and when the thickness is 1.5 mm or more, the bending vibration of the vibrator 12 is excessive. This is because a sufficient driving force cannot be obtained. Furthermore, the elastic member 35 having such a thickness has an inner peripheral surface that is smaller than the outer periphery of the vibrator 12, thereby compressing and holding the vibrator 12 and an outer surface larger than the inner peripheral surface of the holding member 32. By having a diameter, the holding member 32 is compression-fitted. Further, between the holding ribs 32r (recessed portions) of the holding member 32 is formed smaller than the thickness of the elastic member 35 so that the elastic member 35 can be compression-fitted.

  As described above, the vibrator 12 can compress and hold the strong vibration node 12e (see FIG. 6) of the vibrator 12 while the elastic member 35 absorbs the size and assembly errors. Since it is compression-fitted between the parts 32r (recesses) in the member 32, excess vibration of the vibrator 12 can be absorbed. Further, even when the vibrator 12 is assembled in a slightly inclined state, the posture of the contact 19 is not deteriorated and can be stably brought into contact with the sliding member 22. Therefore, efficient driving of the actuator can be obtained.

  As described above, since the vibrator 12 compresses and holds the bending vibration node 12e by the elastic member 35, the contactor posture is deteriorated even if the vibrator 12 is assembled in a slightly inclined state. Without being able to make stable contact. For this reason, the actuator can be efficiently and stably driven. At the same time, it is possible to provide a piezoelectric actuator that can realize generation of abnormal noise without propagating excessive vibration that does not directly affect the driving force to other members.

  By the way, the vibrator 12 has a plurality of rectangular piezoelectric elements stacked and has an internal electrode on the surface of the piezoelectric element. The internal electrode is provided on the surface of the piezoelectric element as a bending vibration electrode, an expansion / contraction electrode, and a ground electrode. It is formed. Each of the bending vibration electrode and the expansion / contraction electrode is laminated in a pair with a ground electrode, and a voltage supply electrode is provided on a side surface of the laminated piezoelectric element. A desired driving operation is performed by appropriately applying a driving voltage between these electrodes.

<< Piezoelectric element wiring pattern constituting the vibrator >>
Hereinafter, the piezoelectric element wiring pattern constituting the vibrator will be described with reference to FIG.
First, electrode patterns formed on each piezoelectric element having a laminated structure constituting the vibrator will be described. The electrode symbols (+, −) shown in FIG. 4 indicate the polarization state inside the piezoelectric element. FIG. 4A is formed on the surface of the piezoelectric element and is connected to the power supply side, and functions as an input pattern of a drive signal. FIG. 4B functions as a drive electrode for a telescopic operation described later. FIG. 4C functions as an input pattern of a driving signal for bending operation described later. FIG. 4D functions as a ground (G) pattern connected to the ground. 4 (e) and 4 (f) function as external extraction patterns for connecting the signals or ground patterns of FIGS. 4 (a) to 4 (d).

  The manner in which the vibrator 12 expands and contracts and bends and vibrates by inputting a signal from the outside to the laminated vibrator 12 will be described with reference to FIGS. 5 (a) to 5 (c) and FIGS. 6 (a) to 6 (c). To do. First, when a driving signal for expansion / contraction operation is input to the vibrator 12, stretching vibration is performed in the longitudinal direction of the vibrator 12, as shown in FIGS. Further, when a driving signal for bending operation is input to the vibrator 12, bending vibration of the vibrator 12 is performed as shown in FIGS.

  As described above, the linear actuator 10 causes the elliptical motion by shifting the phase of the driving power signal frequency for causing the vibrator 12 to expand and contract and the driving power signal frequency for bending vibration by approximately 90 °, thereby causing the sliding member 52 to move. move. In order to reverse the moving direction of the sliding member, the phase of the input signal is reversed.

<<<<< Width (W) / Length (L) ratio of laminated vibrators >>>
Hereinafter, the ratio (W / L) between the width (W) and the length (L) of the laminated vibrator will be described.
As shown in FIG. 3, the vibrator 12 has a moving speed and power consumption of the vibrating unit 11 such that the ratio of the length L to the width W (W / L) is 0.21 <W / L <0.26. In view of the above, it is more preferable to satisfy 0.22 ≦ W / L ≦ 0.25.

  Hereinafter, the reason will be described with reference to Table 2. <Table 2> shows the moving speed (mm / s) of the sliding member 52 and the power consumption at that time (W / L) by changing the ratio (W / L) of the length (L) to the width (W) of the vibrator 12. W) was measured. Here, the moving speed of the sliding member 52 represents the driving efficiency of the piezoelectric actuator, and the power consumption means that the smaller the value, the more efficiently the driving force can be obtained.

＜測定条件＞
・負荷：５０ｇ
・駆動電圧：３．５〜４．５Ｖｒｍｓ
・駆動周波数 ：１５０〜１７０ＫＨｚ <Table 2>

<Measurement conditions>
・ Load: 50g
・ Drive voltage: 3.5-4.5Vrms
・ Drive frequency: 150-170KHz

The meanings of “◎ (double circle)”, “◯ (circle)”, “Δ (triangle)”, and “× (X)” described in the evaluation results in the table are described below.
(Moving body speed)
A: 75 mm / s or more,
○: 50 mm / s / more and 75 mm / s or less Δ: 30 mm / s or more and less than 50 mm / s ×: less than 30 mm / s (power consumption)
◎: Less than 1W
○: 1W or more and less than 1.5W
Δ: 1.5 W or more and less than 2 W
×: 2W or more
From the evaluation results of <Table 2>, in order to satisfy both the moving body speed (mm / s) and the power consumption (W), the ratio of the width (W) to the length (L) of the vibrator 11 (W It can be seen that / L) needs to be larger than 0.21 and smaller than 0.26. Further, it can be seen that the ratio is more preferably 0.22 or more and 0.25 or less. Thus, by optimizing the shape of the vibrator 11, a piezoelectric actuator capable of obtaining a highly efficient driving force can be realized.

  Hereinafter, another aspect of the present embodiment will be described with reference to FIG. In the present embodiment, as shown in FIG. 7, the base portion 16 b and both wall surface portions 16 s of the housing 16 are integrally formed by injection molding together with bearing portions 65 and 66 that support the bearings 53 to 55. However, it is not limited to this. For example, as shown in FIG. 8, a metal part cut out by cutting may be produced and fixed with screws.

  Specifically, as shown in FIG. 8, the housing 16 is made up of two parts to be assembled by a base portion (first member) 16b and both wall surface portions (second members) 16s, and is positioned by positioning pins P. It is also possible to adopt a structure for fixing with screws. In this case, by using a metal, it is possible to improve the component strength and processing accuracy, and it is possible to reduce the cost by reducing the processing cost. Further, since the cutting can be produced in a small amount, the applicability can be improved by easily changing the size or the like according to the dimensional structure of the apparatus main body on which the linear actuator 10 is mounted.

  The scope of the present invention is not limited to the illustrated and described exemplary embodiments, but includes all embodiments that provide the same effects as those intended by the present invention. For example, the same effect can be obtained even when applied to an actuator that moves circularly.

DESCRIPTION OF SYMBOLS 10 ... Linear type actuator 11 ... Vibration unit 12 ... Vibrator 12e ... Bending vibration node 12m ... Stretching vibration node 12P ... Piezoelectric element 13 ... Pressure member 14 ... Tension spring 16 ... ... Housing 16b ... Base 19 ... Contact 31 ... Vibrator assembly
32 …… Holding member 35 …… Elastic member 52 …… Sliding member 52a …… Sliding member convex portion 53 to 55 …… Bearing 100 …… Exterior case 101 …… Lower case 111 …… Upper case

Claims (5)

In a linear actuator including a vibrator composed of a piezoelectric element having a laminated structure that generates combined vibration of stretching vibration and bending vibration, and having a moving body that can reciprocate only in one direction,
A pressurizing member that pressurizes the vibrator by bringing one end of the vibrator into contact with the sliding member;
A vibration unit that includes at least the vibrator and is installed on a support member and functions as the moving body that reciprocates in a horizontal plane;
A linear actuator comprising: a rolling member in contact with a surface opposite to a surface of the sliding member on which the vibrator contacts. The rolling member is attached to a support member on which the vibration unit is installed,
On the surface of the sliding member that contacts the rolling member, a convex portion or a concave portion is formed,
At least one rolling member is arranged in a direction orthogonal to the moving direction of the vibration unit and on one side of the convex portion or the concave portion of the sliding member, and the total number of the rolling members is three. The linear actuator according to claim 1. The linear actuator according to claim 1, wherein the support member includes a first member on which the rolling member is disposed and a plurality of second members to which the vibration unit is attached. 4. The linear device according to claim 1, wherein the vibrator constituting at least a part of the vibration unit includes an elastic member disposed so as to surround at least two node portions of the bending vibration. 5. Type actuator. When the length of the vibrator is L and the width is W, the following expression (1) is satisfied. 0.21 <W / L <0.26 (1)
The linear actuator according to any one of claims 1 to 4.

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