WO2016185900A1

WO2016185900A1 - Drive device

Info

Publication number: WO2016185900A1
Application number: PCT/JP2016/063425
Authority: WO
Inventors: 亨今井; 愛美大塚; 征士朗後藤
Original assignee: 株式会社村田製作所
Priority date: 2015-05-15
Filing date: 2016-04-28
Publication date: 2016-11-24
Also published as: JP6406444B2; JPWO2016185900A1

Abstract

Provided is a drive device that generates little variability in magnitude of displacement. A drive device 1 that has a drive unit 2 and a moving body 3 that is moved in a direction that connects a first main surface 5a and a second main surface 5b of an elastic body 5. The drive unit 2 includes the flexible body 5 and a plurality of piezoelectric elements 6-9. The piezoelectric elements 6-9 are provided to edge sections that surround an opening 5c in the elastic body 5. The piezoelectric elements 6-9 have an active region that is sandwiched between excitation electrodes and inactive regions A1, A2 that are not sandwiched between the excitation electrodes, the inactive regions A1, A2 being arranged in the same manner at all of the plurality of edge sections of the elastic body 5.

Description

Drive device

The present invention relates to a drive device that moves a moving body by driving a piezoelectric element.

Conventionally, various drive devices using piezoelectric elements have been proposed as drive devices for moving a lens of a camera or the like.

The following Patent Document 1 discloses an ultrasonic motor using bending vibration and other vibrations. Here, the cylindrical moving body is inserted into the through hole of the disk-shaped base. The cylindrical moving body is configured to move in the axial direction thereof. Piezoelectric elements are provided on both sides of the disk-shaped substrate. A combined resonance of the bending vibration and radial vibration of the disk is used.

JP-A-1-298968

Conventionally, in a drive device using a piezoelectric element, variation in the amount of displacement of a moving body may occur.

An object of the present invention is to provide a drive device with little variation in displacement.

The drive device according to the present invention has an opening having first and second main surfaces facing each other and penetrating a central portion from the first main surface toward the second main surface. And an elastic body having a plurality of sides surrounding the opening, and at least one main surface of the first and second main surfaces of the elastic body joined to the plurality of sides. A drive unit including the piezoelectric element, and the first main surface and the second main surface of the elastic body by being inserted into the opening of the elastic body and driving the drive unit. By driving the movable body moving in the direction connecting the two and the plurality of piezoelectric elements, the drive unit is caused to generate bending vibration and at least one other vibration different from the bending vibration, or the bending vibration. And at least one different from the bending vibration Of the elastic body so that the vibration of the other mode or the coupling mode can move the movable body. The movable state in which the movable body is frictionally engaged with the inner wall of the opening, and the inner wall of the opening of the elastic body is separated from the movable body, or the friction is lower than in the movable state. The movable body has a vibration state that realizes a release state in which the moving body is in contact with the inner wall of the opening of the elastic body by an engagement force, and the bending unit and the other vibration of the drive unit or The movable body is moved by the vibration of the coupling mode, and the plurality of piezoelectric elements are sandwiched between the plate-like piezoelectric body, the plurality of excitation electrodes for exciting the piezoelectric body, and the excitation electrode. Active region , And a non-active region not sandwiched between the excitation electrode, the inactive region in the plurality of piezoelectric elements are arranged similarly in all of the plurality of side portions.

In a specific aspect of the drive device according to the present invention, the first and second piezoelectric elements are provided on the surfaces of the piezoelectric bodies opposite to the surfaces bonded to the elastic bodies. The first terminal electrode in the plurality of piezoelectric elements is adjacent to the second terminal electrode of the plurality of piezoelectric elements in each adjacent side portion.

In a specific aspect of the drive device according to the present invention, the first terminal electrode and the second terminal electrode adjacent to the first terminal electrode in adjacent side portions are electrically connected. A connecting electrode pad is further provided. In this case, the number of portions that electrically connect the driving device to the outside can be reduced. Therefore, electrical connection is facilitated.

In another specific aspect of the drive device according to the present invention, the opening of the elastic body has a rectangular planar shape, the side portions are first to fourth side portions, and the plurality of piezoelectric elements These are the first to fourth piezoelectric elements joined to the first to fourth sides.

In another specific aspect of the drive device according to the present invention, the piezoelectric element is a stacked piezoelectric element having the plurality of excitation electrodes stacked via piezoelectric layer portions in the piezoelectric body. In this case, the displacement of the drive unit can be increased.

However, in the drive device according to the present invention, the piezoelectric element is provided on the surface of the piezoelectric body opposite to the elastic body, and the first excitation electrode provided on the surface of the piezoelectric body on the elastic body side. A single-plate-type piezoelectric element may be used.

In another specific aspect of the driving apparatus according to the present invention, the moving body has a columnar shape extending in a direction connecting the first main surface and the second main surface of the elastic body.

In still another specific aspect of the drive device according to the present invention, the drive device further includes a spring member extrapolated to the movable body, and the spring member is pressed against the inner wall of the opening of the elastic body of the drive unit. Is done. In this case, the moving body can be moved effectively by the drive unit.

According to the drive device according to the present invention, it is possible to reduce the variation in the amount of displacement of the plurality of sides surrounding the opening of the elastic body. Therefore, the moving body can be moved stably.

FIG. 1A is a perspective view of a drive unit used in the first embodiment of the present invention, and FIG. 1B is a front sectional view of a piezoelectric element used in the drive unit. is there. FIG. 2 is a perspective view of the drive unit used in the comparative example. FIG. 3 is a perspective view of the driving apparatus according to the first embodiment of the present invention. FIG. 4 is a diagram illustrating a relationship between each resonance frequency of bending vibration and spread vibration excited by the drive unit used in the first embodiment and the thickness of the elastic body. In the driving apparatus according to the first embodiment of the present invention, FIG. 5A is a schematic diagram for explaining an initial state. FIG. 5B is a schematic diagram for explaining the movable state. FIG. 6A and FIG. 6B are schematic views for explaining a state in which each moving body is moved in the driving apparatus according to the first embodiment of the present invention. FIG. 7 is a diagram showing the relationship between the amount of displacement of the portion pressed against the moving body on each side of the drive unit in the drive device according to the first embodiment of the present invention, the applied voltage, and time. FIG. 8 is a diagram showing the relationship between the amount of displacement of the portion pressed against the moving body on each side of the drive unit in the drive device of the comparative example, the applied voltage, and time. FIG. 9 is a perspective view of a drive unit according to the second embodiment of the present invention. FIG. 10 is a front sectional view of a piezoelectric element used in Modification 2 of the first embodiment of the present invention. FIG. 11 is a perspective view of a moving body used in Modification 1 of the first embodiment of the present invention. FIG. 12 is a perspective view showing a spring member attached to the movable body shown in FIG.

Hereinafter, the present invention will be clarified by describing specific embodiments of the present invention with reference to the drawings.

It should be pointed out that each embodiment described in this specification is an example, and a partial replacement or combination of configurations is possible between different embodiments.

(First embodiment)
FIG. 1A is a perspective view showing a drive unit used in the first embodiment of the present invention, and FIG. 1B is a front sectional view of a piezoelectric element used in the drive unit. FIG. 3 is a perspective view showing the driving apparatus according to the first embodiment.

As shown in FIG. 3, the drive device 1 includes a drive unit 2 and a moving body 3.

As shown in FIG. 3, the drive unit 2 includes a base member 10 and an elastic body 5 supported by the base member 10. As shown in FIG. 1A, the elastic body 5 has a first main surface 5a and a second main surface 5b that face each other. The elastic body 5 is made of an appropriate rigid material such as metal. In this embodiment, the elastic body 5 has a rectangular frame shape and has an opening 5c in the center. A plurality of piezoelectric elements 6 to 9 are bonded on the first main surface 5a.

The plurality of piezoelectric elements 6 to 9 may be bonded to the second main surface 5b instead of the first main surface 5a. A plurality of piezoelectric elements may be bonded to both main surfaces.

FIG. 1B is a front sectional view of the piezoelectric element 6. The piezoelectric element 6 is a stacked piezoelectric element. The piezoelectric element 6 has a piezoelectric body 11. The piezoelectric body 11 has a strip-like shape having a lateral direction and a longitudinal direction. The piezoelectric body 11 has a first main surface 11a extending in the longitudinal direction, and a second main surface 11b facing the first main surface 11a. The first end face 11c is located on one end side in the longitudinal direction of the piezoelectric body 11, and the second end face 11d is located on the other end side in the longitudinal direction.

Further, an excitation electrode 12 is provided on the first main surface 11 a of the piezoelectric body 11. An excitation electrode 13 is provided in the piezoelectric body 11 so as to face the excitation electrode 12 through the piezoelectric layer. Further, excitation electrodes 14 to 16 are provided in the piezoelectric body 11 so as to be adjacent to each other through the piezoelectric layer. An excitation electrode 17 is provided on the second main surface 11b so as to face the excitation electrode 16 with the piezoelectric layer interposed therebetween. The

excitation electrodes

12, 14, and 16 are drawn out to the first end face 11c. A connection electrode 18 is provided on the first end face 11c. The

excitation electrodes

12, 14, and 16 are electrically connected by the connection electrode 18. On the other hand, the

excitation electrodes

13, 15, and 17 reach the second end face 11d. A connection electrode 19 is provided on the second end face 11d. The

excitation electrodes

13, 15, and 17 are electrically connected by the connection electrode 19.

The connection electrode 18 has a terminal portion 18a reaching the second main surface 11b. The terminal portion 18a and the excitation electrode 17 are formed at positions adjacent to each other via a gap. The connection electrode 19 has a terminal portion 19a that reaches the first main surface 11a. The terminal portion 19a and the excitation electrode 12 are formed at positions adjacent to each other via a gap.

As shown in FIG. 1A, the piezoelectric element 6 is fixed with the excitation electrode 17 side in close contact with the first main surface 5 a of the elastic body 5.

Using the excitation electrode 12 and the terminal portion 19a of the connection electrode 19, it can be electrically connected to the outside. In the present embodiment, the excitation electrode 12 also serves as the first terminal electrode, and the terminal portion 19a serves as the second terminal electrode. The piezoelectric layer between the excitation electrodes 12 to 17 is polarized in the thickness direction. Therefore, when an AC voltage is applied between the excitation electrode 12 serving also as a terminal electrode and the terminal portion 19a, the piezoelectric element 6 vibrates due to bending vibration.

The piezoelectric elements 7 to 9 also have the same structure as the piezoelectric element 6. Therefore, the same parts are denoted by the same reference numerals, and the description thereof is omitted.

When the

piezoelectric elements

6 and 8 and the piezoelectric elements 7 and 9 are driven by bending vibrations having opposite phases, the driving unit 2 generates bending vibrations and spreading vibrations. In the present embodiment, the moving body 3 shown in FIG. 3 is moved by utilizing the coupling mode of the bending vibration and the spreading vibration. The moving body 3 has a cylindrical shape in the present embodiment, and the moving body 3 is moved in the axial direction of the cylindrical shape. In other words, the moving body 3 is moved in a direction connecting the first main surface 5a and the second main surface 5b of the elastic body 5 of the drive unit 2. The operation of moving the moving body 3 will be described in detail later.

A feature of the present embodiment is that in the piezoelectric elements 6 to 9, inactive regions to be described later are similarly arranged on all of the plurality of sides of the elastic body 5 in the rectangular frame shape. This will be described in more detail.

As shown in FIG. 1, the elastic body 5 has a square opening 5c. That is, the elastic body 5 is a rectangular frame having four sides.

Piezoelectric elements

6, 7, 8 or 9 are fixed on the first main surface 5 a in the first to fourth sides of the elastic body 5.

When the piezoelectric element 6 is driven, the entire piezoelectric body 11 is not displaced. That is, the piezoelectric layer portion sandwiched between the excitation electrodes connected to different potentials is displaced by the piezoelectric effect. In this case, in FIG. 1B, the hatched portion of the cross is not sandwiched between the excitation electrodes having different potentials. Accordingly, since the portion is not positively displaced due to the piezoelectric effect, the regions indicated by the cross hatching are defined as inactive regions A1 and A2. The remaining area becomes an active area displaced by the piezoelectric effect.

As shown in FIG. 1B, the inactive region A1 extends in the thickness direction, which is a direction connecting the first and second

main surfaces

11a and 11b of the piezoelectric element 6, along the first end surface 11c. Yes. And it has reached the opposing area | region of the excitation electrode 17 and the terminal part 18a. That is, on the second main surface 11 b side of the piezoelectric body 11, the inactive region A <b> 1 extends from the first end surface 11 c to the tip end side of the excitation electrode 17. Therefore, in the front sectional view, the inactive region A1 has an L-shape.

On the other hand, on the second end face 11d side, the inactive region A2 extends along the second end face 11d. Further, the inactive region A2 extends from the second end surface 11d toward the tip of the excitation electrode 12 along the terminal portion 19a. Therefore, in the front sectional view, the inactive region A2 has an inverted L-shaped shape.

Accordingly, the piezoelectric element 6 passes through the center in the direction connecting the first main surface 11a and the second main surface 11b, is parallel to the first main surface 11a, and is parallel to the longitudinal direction. The top and bottom are asymmetrical. Therefore, the piezoelectric element 6 can be fixed to the elastic body 5 so that the first main surface 11a and the second main surface 11b are reversed.

However, in the present embodiment, as described above, the piezoelectric element 6 is fixed to the elastic body 5 so that the surface on which the excitation electrode 12 is provided is the surface opposite to the joint surface with the elastic body 5. . The remaining piezoelectric elements 7 to 9 are also fixed to the elastic body 5 so that the surface on which the excitation electrode 12 is provided is in the same direction as the piezoelectric element 6.

That is, the first terminal electrodes of the plurality of piezoelectric elements 6 to 9 are adjacent to the second terminal electrodes of the plurality of piezoelectric elements on the adjacent sides. Specifically, the excitation electrode 12 in the piezoelectric element 6 is adjacent to the terminal portion 19 a in the piezoelectric element 9. The excitation electrode 12 in the piezoelectric element 9 is adjacent to the terminal portion 19 a in the piezoelectric element 8. The excitation electrode 12 in the piezoelectric element 8 is adjacent to the terminal portion 19 a in the piezoelectric element 7. The excitation electrode 12 in the piezoelectric element 7 is adjacent to the terminal portion 19 a in the piezoelectric element 6. The excitation electrodes 12 in the

piezoelectric elements

6 and 8 are electrically connected to each other. The excitation electrodes 12 in the piezoelectric elements 7 and 9 are electrically connected to each other. The terminal portions 19a of the

piezoelectric elements

6 and 8 are electrically connected to each other. The terminal portions 19a of the piezoelectric elements 7 and 9 are electrically connected to each other. Therefore, the position of the inactive region of the piezoelectric element in each side portion of the elastic body 5 is similarly arranged in all the side portions of the elastic body 5 in the rectangular frame shape. Therefore, variation in the amount of displacement at each side portion of the drive unit 2 can be reduced. Therefore, the moving body 3 can be stably moved using the driving device 1. This will be clarified by comparing with the comparative example shown in FIG.

The drive unit 101 shown in FIG. 2 is the drive unit of the above embodiment except that the

piezoelectric elements

6A and 8A are fixed on the first main surface 5a of the elastic body 5 instead of the

piezoelectric elements

6 and 8. It is comprised similarly to 2. That is, the piezoelectric element 6 </ b> A is fixed to the elastic body 5 so that the excitation electrode 17 and the terminal portion 18 a are on the surface opposite to the joint surface with the elastic body 5. The same applies to the piezoelectric element 8A. Further, the excitation electrode 17 of the piezoelectric element 6A and the excitation electrode 17 of the piezoelectric element 8A are electrically connected. The excitation electrode 12 of the piezoelectric element 7 and the excitation electrode 12 of the piezoelectric element 9 are electrically connected. The terminal portion 18a of the piezoelectric element 6A and the terminal portion 18a of the piezoelectric element 8A are electrically connected. The terminal portion 19a of the piezoelectric element 7 and the terminal portion 19a of the piezoelectric element 9 are electrically connected. In the comparative example, the

excitation electrodes

12 and 17 are first terminal electrodes, and the

terminal portions

18a and 19a are second terminal electrodes. In the piezoelectric element 6A and the piezoelectric element 8A, the position of the inactive region is the same at the side of the rectangular frame shape of the elastic body 5, but the

piezoelectric elements

6A and 8A and the piezoelectric elements 7 and 9 have the rectangular shape of the elastic body 5. The position of the inactive region is different in the frame-shaped side portion. Therefore, the positions of the inactive regions A1 and A2 described above are not similarly arranged in all the sides of the elastic frame 5 in the rectangular frame shape.

The comparison between the above embodiment and the comparative example will be described later based on an experimental example. Before that, a configuration for moving the moving body 3 in the driving apparatus 1 will be described.

As described above, in this embodiment, a coupling mode of bending vibration and spreading vibration of the elastic body 5 is used. A plurality of coupled modes can be generated by adjusting the resonance frequency of the bending vibration and the spreading vibration.

When an AC voltage is applied to the piezoelectric elements 6 to 9, the elastic body 5 vibrates due to bending vibration and spreading vibration.

FIG. 4 is a diagram showing the relationship between the resonance frequency of bending vibration and the resonance frequency of spread vibration and the thickness of the elastic body 5. As shown in FIG. 4, by adjusting the thickness of the elastic body 5, the resonance frequency of the bending vibration and the resonance frequency of the spreading vibration can be adjusted, and a coupling mode of both can be generated. As will be described later, two coupling modes of a first coupling mode and a second coupling mode among a plurality of coupling modes are used.

In this embodiment, the first coupling mode and the second coupling mode are used. The vibration in the first and second coupling modes is caused by the movable state in which the inner wall of the opening 5c of the elastic body 5 is pressed against the moving body 3 and the inner wall of the opening 5c being separated from the moving body 3. Or a vibration state that realizes a released state in contact with the moving body 3 with a frictional engagement force lower than that in the movable state. That is, in any case of the first coupling mode and the second coupling mode, a vibration state that realizes the two states is generated.

However, in the first coupling mode, the movable body 3 is moved to one side in the axial direction of the movable body 3 in the movable state in the first coupling mode. If this is a forward movement, in the second coupling mode, the inner wall of the opening part moves the moving body 3 backward in the movable state. That is, the moving body 3 can be moved forward or backward by switching the driving frequency so that the first coupling mode and the second coupling mode are generated.

As described above, in the present embodiment, the first and second coupling modes in which the vibration state realizing the release state and the movable state are generated are used. In order to make the coupling, it is preferable that the resonance frequency of the bending vibration and the resonance frequency of the spreading vibration are matched. However, the resonance frequencies of both may not be exactly the same, and the absolute value of the difference between the resonance frequency of the bending vibration and the resonance frequency of the spread vibration is the resonance frequency in the first coupling mode and the second coupling mode. What is necessary is just to be in the range within 15% of the average value of resonance frequency.

Note that, in this embodiment, a coupled mode of bending vibration and spreading vibration is used, but bending vibration and coupled mode may be used. Further, bending vibration and vibration modes other than bending vibration such as spreading vibration may be used.

FIG. 5 (a) shows an initial state when operating the drive device 1, and as shown in FIG. 5 (b), by driving the drive unit 2 to generate the first coupling mode as described above. Thus, the movable state is set. That is, the opening 5 c of the elastic body 5 is pressed against the outer peripheral surface of the moving body 3. In this state, by moving in the first coupling mode, the moving body 3 can be advanced in the direction of the arrow, that is, one side in the axial direction, as shown in FIG. And in a 1st coupling | bonding mode, as shown in FIG.6 (b), advancing is stopped by implement | achieving a release state. By repeating these steps, the moving body 3 can be pitched forward.

In the case of retreating, the movable body 3 can be retreated by generating the second coupling mode and driving in the second coupling mode. For example, the movable body 3 may be moved forward or backward by bending vibration, and the release state and the movable state may be realized by spreading vibration.

Next, according to the driving device 1 of the present embodiment, the inactive regions of the piezoelectric elements 6 to 9 are similarly arranged in all of the plurality of sides of the elastic body 5 in the rectangular frame shape. Therefore, it will be described with reference to FIG. 7 and FIG. 8 that the variation in the side of the displacement amount of the moving body can be reduced, thereby reducing the variation in the entire displacement amount of the moving body.

7 represents a driving voltage waveform in the driving device of the first embodiment. Further, the broken line, the alternate long and short dash line, the alternate long and two short dashes line, and the thin line indicate the amount of displacement of the inner wall portion of the central opening 5c of each side where the piezoelectric elements 6 to 9 are provided. The central inner wall portion of each side portion is a portion pressed against the moving body 3.

FIG. 8 is a diagram showing a displacement amount of a central inner wall portion of each side portion and a driving voltage waveform in the driving device of the comparative example described above. The amount of displacement is determined by, for example, irradiating the inner wall portion of the central opening of each side of the drive device with a Doppler vibrometer manufactured by Ono Sokki Co., Ltd. under the trade name “LV-1710”, and reflecting the irradiated laser The light was measured by receiving light with a Doppler vibrometer. As shown in FIGS. 7 and 8, the drive voltage having the same waveform is applied to the drive device of the first embodiment and the drive device of the comparative example. However, in the drive device of the comparative example, the center of each side portion is applied. It can be seen that the amount of displacement of the inner wall portion of the opening varies greatly. On the other hand, as shown in FIG. 7, in the driving device of the first embodiment, the displacement amount of the inner wall portion of the opening at the center of each side portion is almost the same, and the variation in the displacement amount is effectively reduced. It can be seen that it can be reduced.

(Second Embodiment)
FIG. 9 is a perspective view showing a drive unit used in the drive apparatus according to the second embodiment of the present invention. The drive unit 22 is the same as the drive unit 2 except that connection pads 23a to 23d are provided. Therefore, the same reference numerals are assigned to the same parts, and the description of the first embodiment is incorporated.

The connection pads 23a to 23d are made of a conductive material. The electrode pad electrically connects the first terminal electrode and the second terminal electrode adjacent to the first terminal electrode in the adjacent side portion. Specifically, the connection pad 23 a electrically connects the terminal portion 19 a of the piezoelectric element 6 and the excitation electrode 12 as the first terminal portion of the piezoelectric element 7. The connection pad 23 b electrically connects the terminal portion 19 a of the piezoelectric element 7 and the excitation electrode 12 of the piezoelectric element 8. The connection pad 23 c electrically connects the terminal portion 19 a of the piezoelectric element 8 and the excitation electrode 12 of the piezoelectric element 9. The connection pad 23 d electrically connects the terminal portion 19 a of the piezoelectric element 9 and the excitation electrode 12 of the piezoelectric element 6. More specifically, the terminal portion 19a of the piezoelectric element 6, the excitation electrode 12 of the piezoelectric element 7, the terminal portion 19a of the piezoelectric element 8, and the excitation electrode 12 of the piezoelectric element 9 are electrically connected. The excitation electrode 12 of the piezoelectric element 6, the terminal portion 19 a of the piezoelectric element 7, the excitation electrode 12 of the piezoelectric element 8, and the terminal portion 19 a of the piezoelectric element 9 are electrically connected.

Therefore, when the drive unit 22 is driven, the four locations on the first main surface 11a side of the piezoelectric body 11 of the piezoelectric elements 6 to 9 may be electrically connected by bonding wires or the like. That is, since the terminal portion 19a of the adjacent piezoelectric element and the excitation electrode 12 are electrically connected in advance by the connection pads 23a to 23d, the number of electrical connection locations with the outside may be four.

In contrast, in the first embodiment described above, in each of the piezoelectric elements 6 to 9, it is necessary to electrically connect the excitation electrode 12 as the first and second terminal electrodes and the terminal portion 19a to the outside. There were 8 electrical connection points with the outside.

Therefore, according to this embodiment, electrical connection with the outside can be easily performed.

That is, as in the second embodiment, between the adjacent piezoelectric elements 6 to 9, it is preferable that the terminal electrodes connected to the same potential are connected in common on the first main surface 11a side.

In the first and second embodiments, the elastic body 5 has a square opening 5c and has a rectangular frame shape. However, the elastic body 5 may have another polygonal opening. Good.

(Modification 1 of the first embodiment)
Moreover, in the said embodiment, the inner surface of the opening part 5c of the said elastic body 5 was press-contacted to the outer peripheral surface of the cylindrical moving body 3, and the moving body 3 was made the movable state. In this case, a spring member made of metal or the like may be fixed to the outer peripheral surface of the moving body 3. Moreover, the moving body 3 is not limited to a columnar shape, and may have a substantially prismatic shape like a moving body 3A shown in FIG. In this case, the spring member 4 shown in FIG. 12 may be attached to the moving body 3A. That is, the inner diameter of the spring member 4 made of metal or the like is made smaller than the maximum dimension in the cross-sectional direction orthogonal to the axial direction of the moving body 3A. Therefore, the spring member 4 may be attached to the moving body 3A while expanding the slit 4a of the spring member 4 having the slit 4a. In this case, the outer peripheral surface of the spring member 4 is pressed against the inner wall of the opening 5 c of the elastic body 5 of the drive unit 2, and the moving body 3 </ b> A is moved together with the spring member 4.

(Modification 2 of the first embodiment)
Further, although multilayer piezoelectric elements are used as the piezoelectric elements 6 to 9, a single plate type piezoelectric element 31 shown in FIG. 10 may be used. The piezoelectric element 31 includes a piezoelectric body 32, a first excitation electrode 33 provided on the first main surface of the piezoelectric body 32, and a second excitation electrode 34 provided on the second main surface. Also in the piezoelectric element 31,

connection electrodes

35 and 36 are provided on both end faces of the piezoelectric body 32, and

terminal portions

35 a and 36 a are connected to the

connection electrodes

35 and 36, respectively. Therefore, also in the piezoelectric element 31, the inactive region is located asymmetrically on both sides of a cross section that passes through the center in the direction connecting the first and second main surfaces of the piezoelectric body 32 and extends parallel to the first main surface. Yes. Therefore, the piezoelectric element 31 is also provided so that the inactive region is located at the same position on all the sides of the elastic body 5 in the rectangular frame shape, similarly to the piezoelectric elements 6 to 9 described above. Thereby, the same effect as in the case of the first embodiment can be obtained.

DESCRIPTION OF SYMBOLS 1 ... Drive device 2 ... Drive unit 3, 3A ... Moving body 4 ... Spring member 4a ... Slit 5 ... Elastic body 5a ... 1st main surface 5b ... 2nd main surface 5c ... Opening

part

6, 7, 8, 9 ...

piezoelectric elements

6A, 8A ... piezoelectric element 10 ... base member 11 ... piezoelectric body 11a ... first main surface 11b ... second main surface 11c ... first end surface 11d ... second end surfaces 12, 13, 14, 15 , 16, 17 ...

excitation electrodes

18, 19 ...

connection electrodes

18a, 19a ... terminal 22 ... drive

units

23a, 23b, 23c, 23d ... connection pads 31 ... piezoelectric element 32 ... piezoelectric element 33 ... first excitation electrode 34 ...

Second excitation electrodes

35, 36 ...

connection electrodes

35a, 36a ... terminal portion 101 ... drive units A1, A2 ... inactive regions

Claims

An opening having first and second main surfaces facing each other and penetrating a central portion from the first main surface toward the second main surface, and a plurality of surroundings surrounding the opening A drive unit comprising: an elastic body having a side portion; and a plurality of piezoelectric elements joined to the plurality of side portions on at least one main surface of the first and second main surfaces of the elastic body. When,
A movable body that is inserted into the opening of the elastic body and is moved in a direction connecting the first main surface and the second main surface of the elastic body by driving the drive unit; ,
By driving the plurality of piezoelectric elements, the driving unit is configured to bend and vibrate and at least one other vibration different from the bending vibration or at least one kind different from the bending vibration and the bending vibration. It is configured to vibrate with a combined mode vibration formed by combining with the other vibrations,
A movable state in which the movable body is frictionally engaged with an inner wall of the opening of the elastic body so that the vibration of the other mode or the coupled mode can move the movable body; The inner wall of the opening is separated from the moving body, or the moving body is in contact with the inner wall of the opening of the elastic body with a lower frictional engagement force than the movable state. Have a vibration mode that realizes
The movable body is moved by the bending vibration and the other vibration of the driving unit or by the vibration of the coupling mode,
The plurality of piezoelectric elements include a plate-shaped piezoelectric body, a plurality of excitation electrodes for exciting the piezoelectric body, an active region sandwiched between the excitation electrodes, and a non- sandwiched area between the excitation electrodes. An active region,
The drive device, wherein the inactive regions in the plurality of piezoelectric elements are similarly arranged in all of the plurality of sides.
Each of the plurality of piezoelectric elements includes first and second terminal electrodes provided on a surface of the piezoelectric body opposite to a surface bonded to the elastic body;
2. The driving device according to claim 1, wherein the first terminal electrodes in the plurality of piezoelectric elements are adjacent to the second terminal electrodes of the plurality of piezoelectric elements in adjacent side portions.
The electrode pad which electrically connects the 1st terminal electrode and the 2nd terminal electrode which adjoins the 1st terminal electrode in an adjoining side part is provided. The drive device described in 1.
The opening of the elastic body has a rectangular planar shape, the side portions are first to fourth side portions, and the plurality of piezoelectric elements are joined to the first to fourth side portions. 4. The driving device according to claim 1, wherein the driving device is a first to a fourth piezoelectric element.
The driving device according to any one of claims 1 to 4, wherein the piezoelectric element is a stacked piezoelectric element having the plurality of excitation electrodes stacked via piezoelectric layer portions in the piezoelectric body. .
The piezoelectric element has a first excitation electrode provided on the surface of the piezoelectric body on the elastic body side, and a second excitation electrode provided on the surface of the piezoelectric body opposite to the elastic body. The driving device according to any one of claims 1 to 4, wherein the driving device is a single plate type piezoelectric element.
The drive device according to any one of claims 1 to 6, wherein the movable body has a cylindrical shape extending in a direction connecting the first main surface and the second main surface of the elastic body. .
The drive device according to claim 7, further comprising a spring member extrapolated to the movable body, wherein the spring member is pressed against the inner wall of the opening of the elastic body of the drive unit.