Actuator

Abstract

This method suppresses stress concentration in the support portion of the piezoelectric vibrator while minimizing adverse effects on the vibration characteristics of the actuator. [Solution] The actuator 10 comprises a piezoelectric vibrator 100 and a support ST1. The piezoelectric vibrator 100 is composed of a laminate including a plate member 31 and a piezoelectric element 21, and has a first main surface and a second main surface facing each other. The support ST1 is ring-shaped in plan view and has a predetermined thickness. The support ST1 comprises an ring-shaped inner circumferential surface FiST1 and outer circumferential surface FeST1, and surfaces FST11 and FST12 that are connected to the inner circumferential surface FiST1 and outer circumferential surface FeST1 and face each other. Surface FST12 is fixed to the first main surface of the piezoelectric vibrator 100. The support ST1 has a thin-walled portion in the thickness direction between surface FST11 and surface FST12, where the distance between the inner circumferential surface FiST1 and the outer circumferential surface FeST1 is shortened by the inner circumferential surface FiST1 being recessed.

Description

Technical Field

[0001] The present invention relates to an actuator including a laminate of a piezoelectric element and a plate member, and a support that supports the laminate in a vibratable manner.

Background Art

[0002] Patent Document 1 describes a configuration in which an outer edge portion of a diaphragm on which a piezoelectric element is disposed is fixed to a housing case. The diaphragm is adhered to the housing case using an adhesive.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the configuration as shown in Patent Document 1, it is difficult to control the thickness and volume of the adhesive (elastic adhesive).

[0005] Therefore, an object of the present invention is to suppress concentration of stress on a portion that supports a piezoelectric vibrator while suppressing an adverse effect on vibration characteristics as an actuator.

Means for Solving the Problems

[0006] An actuator according to an embodiment of the present invention includes a piezoelectric vibrator and a first support. The piezoelectric vibrator is composed of a laminate including a plate member and a piezoelectric element, and has a first main surface and a second main surface facing each other. The first support has an annular shape in plan view and a predetermined thickness.

[0007] The first support comprises an annular inner and outer circumferential surface, and third and fourth surfaces connected to and facing the inner and outer circumferential surfaces. The third surface is fixed to the first main surface of the piezoelectric vibrator. The first support has a thin-walled portion between the third and fourth surfaces in the thickness direction, formed by a recess in the inner circumferential surface, which shortens the distance between the inner and outer circumferential surfaces.

[0008] In this configuration, the stress on the inner circumferential surface end point (inner endpoint) of the surface to which the piezoelectric vibrator is fixed is relieved by the recess formed by the thin-walled portion of the first support. [Effects of the Invention]

[0009] The objective of this invention is to suppress stress concentration in the part supporting the piezoelectric vibrator while suppressing adverse effects on the vibration characteristics of the actuator. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 is an exploded perspective view of the actuator according to the first embodiment. [Figure 2] Figure 2 is an exploded perspective view of the actuator according to the first embodiment. [Figure 3] Figures 3(A) and 3(B) are perspective views of the support, and Figure 3(C) is a cross-sectional view of the support. [Figure 4] Figures 4(A) and 4(B) are cross-sectional views showing a part of the actuator according to the first embodiment. [Figure 5] Figure 5 is a graph showing the maximum stress for the present configuration and a comparative configuration. [Figure 6] Figure 6 is a cross-sectional view showing a part of the actuator according to the second embodiment. [Figure 7] Figure 7 is a cross-sectional view showing a part of the actuator according to the third embodiment. [Figure 8] Figure 8 is a cross-sectional view showing a part of the actuator according to the fourth embodiment. [Figure 9]Figure 9 is a cross-sectional view showing a part of the actuator according to the fifth embodiment. [Modes for carrying out the invention]

[0011] [First Embodiment] An actuator according to the first embodiment of the present invention will be described with reference to the figures. Figures 1 and 2 are exploded perspective views of the actuator according to the first embodiment. Figures 1 and 2 are views of each other in opposite directions in the stacking direction. Figures 3(A) and 3(B) are perspective views of the support, and Figure 3(C) is a cross-sectional view of the support. Figures 4(A) and 4(B) are cross-sectional views showing a part of the actuator according to the first embodiment. Figures 4(A) and 4(B) show one outer edge (support) side from the center of the actuator.

[0012] Note that the black circles in each figure, which indicate points (for example, the center point), represent geometric positions and do not need to be physically visible objects. Also, in the following explanation, viewing each component of the actuator 10 in the stacking direction is referred to as a plan view of each conceptual element.

[0013] As shown in Figures 1, 2, 4(A), and 4(B), the actuator 10 comprises a piezoelectric element 21, a piezoelectric element 22, a plate member 31, a plate member 32, a plate member 33, a support ST1, and a support ST2. The piezoelectric vibrator 100 is formed by the piezoelectric elements 21, 22, 31, 32, and 33.

[0014] The piezoelectric element 21 comprises a piezoelectric body 210, a driving electrode 211, and a driving electrode 212. The piezoelectric body 210 is a disc. The piezoelectric body 210 has a surface F211, a surface F212, and an outer edge Fe21.

[0015] Surfaces F211 and F212 are circular when viewed in a perpendicular direction (plan view). Surfaces F211 and F212 face each other. The outer edge Fe21 is circular when viewed in plan.

[0016] The drive electrode 211 is disposed on the surface F211. The drive electrode 211 is circular in plan view. The drive electrode 212 is disposed on the surface F212. The drive electrode 212 is circular in plan view. The drive electrodes 211 and 212 are in a shape that overlaps in plan view.

[0017] The drive electrodes 211 and 212 are thin films, for example, thinner than the thickness of the piezoelectric body 210. The drive electrodes 211 and 212 are formed, for example, by vapor deposition treatment, sputtering treatment, etc. on the surfaces F211 and F212 of the piezoelectric body 210. The drive electrodes 211 and 212 are electrodes for the purpose of applying a voltage to the piezoelectric body 210. In other words, the drive electrodes 211 and 212 hardly have the function of generating the bending vibration of the actuator 10 by utilizing the strain of the piezoelectric body 210.

[0018] The piezoelectric element 22 has the same configuration as the piezoelectric element 21. The piezoelectric element 22 includes a piezoelectric body 220, a drive electrode 221, and a drive electrode 222. The piezoelectric body 220 is a disk. The piezoelectric body 220 has a surface F221, a surface F222, and an outer edge Fe22.

[0019] The surfaces F221 and F222 are circular when viewed in directions perpendicular to each other (in plan view). The surface F221 and the surface F222 face each other. The outer edge Fe22 is circular in plan view.

[0020] The drive electrode 221 is disposed on the surface F221. The drive electrode 221 is circular in plan view. The drive electrode 222 is disposed on the surface F222. The drive electrode 222 is circular in plan view. The drive electrodes 221 and 222 are in a shape that overlaps in plan view.

[0021] The driving electrodes 221 and 222 are thin films, for example, thinner than the thickness of the piezoelectric body 220. The driving electrodes 221 and 222 are formed on surfaces F221 and F222 of the piezoelectric body 220 by processes such as vapor deposition and sputtering. The driving electrodes 221 and 222 are electrodes intended to apply a voltage to the piezoelectric body 220. In other words, the driving electrodes 221 and 222 do not have the function of generating bending vibrations of the actuator 10 by utilizing the strain of the piezoelectric body 220.

[0022] The plate member 31 is made of, for example, metal. The plate member 31 is a disc. The plate member 31 has a surface F311, a surface F312, and an outer edge Fe31.

[0023] Surfaces F311 and F312 are circular when viewed in a direction perpendicular to each other (in a plan view). Surfaces F311 and F312 face each other. The outer edge Fe31 is circular when viewed in a plan view.

[0024] The plate member 32 has the same configuration as the plate member 31. The plate member 32 is made of, for example, metal. The plate member 32 is a disc. The plate member 32 has a surface F321, a surface F322, and an outer edge Fe32.

[0025] Surfaces F321 and F322 are circular when viewed in a direction perpendicular to each other (in a plan view). Surfaces F321 and F322 face each other. The outer edge Fe32 is circular when viewed in a plan view.

[0026] The plate member 33 is made of metal and is a disc. The plate member 33 has an outer edge Fe 33.

[0027] The piezoelectric elements 21, 22, plate members 31, 32, and 33 are stacked as follows to constitute the piezoelectric vibrator 100.

[0028] The plate member 31 is placed on the surface F211 of the piezoelectric element 21 and bonded to it with an adhesive or the like. More specifically, the plate member 31 is placed on the piezoelectric element 21 with its surface F312 adjacent to and facing the surface F211.

[0029] The plate member 33 is placed on the surface F212 of the piezoelectric element 21 and bonded to it with an adhesive or the like.

[0030] The piezoelectric element 22 is placed on the surface of the plate member 33 opposite to the surface on which the piezoelectric element 21 is placed, and is bonded to it with an adhesive or the like. In this case, the surface F222 of the piezoelectric element 22 is adjacent to and facing the plate member 33.

[0031] The plate member 32 is placed on the surface F221 of the piezoelectric element 22 and bonded to it with an adhesive or the like. More specifically, the plate member 32 is placed on the piezoelectric element 22 with its surface F322 adjacent to and facing the surface F221.

[0032] In this case, when viewed from above (viewed in the stacking direction), the center point Po31 of plate member 31, the center point Po21 of piezoelectric element 21, the center point Po33 of plate member 33, the center point Po22 of piezoelectric element 22, and the center point Po32 of plate member 32 overlap (contend). Here, overlap (contend) means that a range of manufacturing tolerances, including assembly errors, is permitted.

[0033] Thus, the piezoelectric vibrator 100, which is composed of a laminate of piezoelectric elements 21, 22, plate members 31, 32, and 33, has a first main surface and a second main surface. The first main surface of the piezoelectric vibrator 100 is composed of the surface F311 of plate member 31. The second main surface of the piezoelectric vibrator 100 is composed of the surface F321 of plate member 32.

[0034] The piezoelectric vibrator 100 is fixed and supported by support ST1 and support ST2.

[0035] Supports ST1 and ST2 are made of highly rigid materials such as metal.

[0036] As shown in Figures 3(A), 3(B), 3(C), 4(A), and 4(B), the support ST1 is annular in shape when viewed from above and has a predetermined thickness H(ST1).

[0037] The support ST1 has a circular inner surface FiST1 and an outer surface FeST1 when viewed from above. The inner surface FiST1 is the inner surface of the annular shape, and the outer surface FeST1 is the outer surface of the annular shape. The width W(ST1) of the support ST1 is defined by the distance between the inner surface FiST1 and the outer surface FeST1.

[0038] The support ST1 has a surface FST11 at one end in the thickness direction, which is an annular plane. The support ST1 has a surface FST12 at the other end in the thickness direction, which is an annular plane. FST12 corresponds to the third surface, and FST11 corresponds to the fourth surface.

[0039] The support ST1 has a recess COV1. The recess COV1 is recessed from the inner circumferential surface FiST1. The recess COV1 is formed around the entire circumference of the inner circumferential surface FiST1 and is annular in shape.

[0040] The recess COV1 is formed in the thickness direction of the support ST1 between surfaces FST11 and FST12. The recess COV1 has a shape that does not reach surfaces FST11 and FST12. By configuring the recess COV1 in this way, the support ST1 has a thin-walled portion TWP1 on the outer peripheral surface FoST1 side of the recess COV1 between surfaces FST11 and FST12 in the thickness direction. In the thin-walled portion TWP1, the distance between the inner peripheral surface FiST1 and the outer peripheral surface FoST1 is shorter than in the portion of the support ST1 where the recess COV1 is not formed.

[0041] The recess COV1 comprises a bottom surface FC1 (the portion of the inner circumferential surface FiST1 whose distance from the outer circumferential surface FoST1 is shorter than that of other parts of the support ST1), a side surface FsC11, and a side surface FsC12. The surface of the recess COV1 referred to here is the surface formed by the support ST1 on which the recess COV1 is formed.

[0042] The bottom surface FC1 is the surface that determines the depth W(COV1) of the recess COV1 and the width of the thin-walled portion TWP1. The side surfaces FsC11 and FsC12 are the surfaces that determine the height H(COV1) of the recess COV1. Side surface FsC11 is the surface of the recess COV1 on the side of the support ST1 FST11, and side surface FsC12 is the surface of the recess COV1 on the side of the support ST1 FST12.

[0043] The recess COV1 (thin-walled portion TWP1) is formed in the thickness direction of the support ST1 at a position closer to surface FST12 than to surface FST11. The distance D(AD1) of the recess COV1 to surface FST12 is defined by the distance between the side surface FsC12 of the recess COV1 and surface FST12.

[0044] The support ST2 has a circular inner surface FiST2 and an outer surface FeST2 when viewed from above. The inner surface FiST2 is the inner surface of the annular shape, and the outer surface FeST2 is the outer surface of the annular shape. The width W(ST2) of the support ST2 is defined by the distance between the inner surface FiST2 and the outer surface FeST2.

[0045] The support ST2 has a surface FST21 at one end in the thickness direction, which is an annular plane. The support ST2 has a surface FST22 at the other end in the thickness direction, which is an annular plane.

[0046] The support ST2 has a recess COV2. The recess COV2 is recessed from the inner circumferential surface FiST2. The recess COV2 is formed around the entire circumference of the inner circumferential surface FiST2 and is annular in shape.

[0047] The recess COV2 is formed in the thickness direction of the support ST2 between surfaces FST21 and FST22. The recess COV2 does not reach surfaces FST21 and FST22. By configuring the recess COV2 in this way, the support ST2 has a thin-walled portion TWP2 on the outer peripheral surface FoST2 side of the recess COV2 between surfaces FST21 and FST22 in the thickness direction. The distance between the inner peripheral surface FiST2 and the outer peripheral surface FoST2 is shorter in the thin-walled portion TWP2 than in the portion of the support ST2 where the recess COV2 is not formed.

[0048] The recess COV2 comprises a bottom surface FC2 (the portion of the inner circumferential surface FiST2 whose distance from the outer circumferential surface FoST2 is shorter than that of other parts of the support ST2), a side surface FsC21, and a side surface FsC22. The surface of the recess COV2 referred to here is the surface formed by the support ST2 on which the recess COV2 is formed.

[0049] The bottom surface FC2 is the surface that determines the depth W(COV2) of the recess COV2 and the width of the thin-walled section TWP2. The side surfaces FsC21 and FsC22 are the surfaces that determine the height H(COV2) of the recess COV2. Side surface FsC21 is the surface of the support ST2 on the side FST21 of the recess COV2, and side surface FsC22 is the surface of the support ST2 on the side FST22 of the recess COV2.

[0050] The recess COV2 (thin-walled portion TWP2) is formed in the thickness direction of the support ST2 at a position closer to surface FST21 than to surface FST22. The distance D(AD2) of the recess COV2 to surface FST21 is defined by the distance between the side surface FsC21 of the recess COV2 and surface FST21.

[0051] Note that the height H(ST1) of support ST1 and the height H(ST2) of support ST2 are the same. The width W(ST1) of support ST1 and the width W(ST2) of support ST2 are the same. However, these heights or widths may be different.

[0052] Furthermore, the depth W(COV1) of recess COV1 and the depth W(COV2) of recess COV2 are the same. In other words, the width of thin-walled section TWP1 and the width of thin-walled section TWP2 are the same. The height H(COV1) of recess COV1 and the height H(COV2) of recess COV2 are the same. In other words, the thickness of thin-walled section TWP1 and the thickness of thin-walled section TWP2 are the same. The distance D(AD1) of recess COV1 from surface FST12 and the distance D(AD2) of recess COV2 from surface FST21 are the same. However, these depths, heights, and distances may be different.

[0053] The support ST1 is positioned on the surface F311 of the plate member 31 (the first main surface of the piezoelectric vibrator 100). In this configuration, the surface FST12 of the support ST1 is adjacent to and facing the first main surface of the piezoelectric vibrator 100.

[0054] The surface FST12 of the support ST1 and the first surface of the piezoelectric vibrator 100 are bonded together by a thin-film adhesive or the like. This adhesive does not need to be elastic, as its primary function is to bond the support ST1 to the plate member 31. In other words, the primary function of this adhesive is to fix the support ST1 to the piezoelectric vibrator 100 with high rigidity.

[0055] The support ST2 is positioned on the surface F321 of the plate member 32 (the second main surface of the piezoelectric vibrator 100). In this case, the surface FST21 of the support ST2 is adjacent to and facing the second main surface of the piezoelectric vibrator 100.

[0056] The surface FST21 of the support ST2 and the second surface of the piezoelectric vibrator 100 are bonded together by a thin-film adhesive. This adhesive does not need to be elastic, as its primary function is to bond the support ST2 to the plate member 32. In other words, the primary function of this adhesive is to fix the support ST2 to the piezoelectric vibrator 100 with high rigidity.

[0057] Supports ST1 and ST2 overlap in a plan view (viewed in the stacking direction). More specifically, in a plan view, the inner circumferential surface FiST1 of support ST1 and the inner circumferential surface FiST2 of support ST2 overlap, and more preferably coincide.

[0058] As a result, in a plan view, the region of the piezoelectric vibrator 100 inside the supports ST1 and ST2 becomes capable of flexural vibration. In this state, supports ST1 and ST2 fix a predetermined width region near the outer edge of the piezoelectric vibrator 100. Therefore, the piezoelectric vibrator 100 is fixed by supports ST1 and ST2 with its outer circumference near the outer edge fixed, while the region closer to the center than the outer circumference is capable of flexural vibration.

[0059] In this configuration, a first drive signal of a predetermined frequency is supplied to the drive electrodes 211 and 212, and a second drive signal of a predetermined frequency is supplied to the drive electrodes 221 and 222. The frequencies of the first and second drive signals are the same. The frequencies of the first and second drive signals are set based on the resonant frequency of the actuator 10, and for example, they are approximately the same as the resonant frequency of the actuator 10. The first and second drive signals are in opposite phase.

[0060] Thus, when the first drive signal is supplied, the piezoelectric element 21 deforms and expands in a direction parallel to planes F211 and F212. Similarly, when the second drive signal is supplied, the piezoelectric element 22 deforms and expands in a direction parallel to planes F221 and F222. The expansion and contraction directions of piezoelectric element 21 and piezoelectric element 22 are opposite.

[0061] The stress due to the stretching strain of the piezoelectric elements 21 and 22 is applied to the plate members 31, 32, and 33. Here, the outer periphery of the piezoelectric vibrator 100 is fixed by supports ST1 and ST2. Therefore, the piezoelectric vibrator 100 generates bending vibration in the region inward from the outer periphery due to the stress due to the stretching strain of the piezoelectric elements 21 and 22. The bending vibration is a vibration that displaces in a direction parallel to the stacking direction, and the point of maximum displacement of this bending vibration approximately coincides with the center point Po of the region of the piezoelectric vibrator 100 that is not fixed by supports ST1 and ST2.

[0062] In this way, plate members 31, 32, and 33 realize the function of generating bending vibrations due to the strain of piezoelectric elements 21 and 22. The material and thickness of plate members 31, 32, and 33 are set based on the resonant frequency set in the actuator 10.

[0063] Furthermore, since plate members 31, 32, and 33 are made of a conductive material, they also function as power supply electrodes for each driving electrode.

[0064] Furthermore, the actuator 10 employs a so-called bimorph configuration by incorporating piezoelectric elements 21 and 22. This allows for a larger amount of vibration during bending.

[0065] In this configuration, support ST1 is provided with a recess COV1, and support ST2 is provided with a recess COV2.

[0066] When the piezoelectric vibrator 100 undergoes bending vibration as described above, a large stress is concentrated at the fixed ends of the piezoelectric vibrator 100 to the support ST1 and support ST2. This stress is concentrated in the portion of the piezoelectric vibrator 100 sandwiched between the support ST1 and support ST2, the interface of the surface FST12 on the support ST1 that contacts the piezoelectric vibrator 100 and its vicinity, and the interface of the surface FST21 on the support ST2 that contacts the piezoelectric vibrator 100 and its vicinity. In particular, the end point (inner end point) on the inner circumferential surface FiST1 side of the surface FST12 to which the piezoelectric vibrator 100 is fixed to the support ST1 is the point where the maximum stress is applied when the piezoelectric vibrator 100 vibrates.

[0067] Here, by forming a recess COV1 that is recessed from the inner circumferential surface FiST1 in the support ST1 (a portion where the distance between the inner circumferential surface FiST1 and the outer circumferential surface FoST1 is shorter than in other portions), the region in the support ST1 where the recess COV1 is formed midway along the thickness direction has relatively lower elasticity compared to other regions of the support ST1. As a result, stress is distributed in the region between the recess COV1 and the surface FST12 of the support ST1.

[0068] Similarly, by forming a recess COV2 in the support ST2 that is recessed from the inner surface FiST2 (a portion where the distance between the inner surface FiST2 and the outer surface FoST2 is shorter than in other portions), the region in the support ST2 where the recess COV2 is formed midway along the thickness direction has relatively lower elasticity compared to other regions of the support ST2. As a result, stress is distributed in the region between the recess COV1 and the surface FST12 of the support ST2.

[0069] This reduces the maximum stress applied to the fixed ends of the piezoelectric vibrator 100 to the supports ST1 and ST2.

[0070] More specifically, on the support ST1 side, the maximum stress is applied to the endpoint PAD1 on the inner circumferential surface FiST1 side of the fixed surface (contact surface) between the piezoelectric vibrator 100 and the support ST1. However, by providing the recess COV1, the stress on the support ST1 side is distributed, and the stress on the endpoint PAD1 is reduced.

[0071] On the support ST2 side, the maximum stress is applied to the endpoint PAD2 on the inner circumferential surface FiST2 side of the fixed surface (contact surface) between the piezoelectric vibrator 100 and the support ST2. However, by providing the recess COV2, the stress on the support ST2 side is distributed, and the stress on the endpoint PAD2 is reduced.

[0072] Figure 5 is a graph showing the maximum stress for the present configuration and the comparative configuration. The present configurations are the configuration of the first embodiment (one recess) and the configuration of the third embodiment (two recesses) shown below. The comparative configuration is one in which the support does not have a recess.

[0073] As shown in Figure 5, the actuator 10 according to the first embodiment can reduce the maximum stress compared to the comparative configuration. As a result, the actuator 10 can suppress stress concentration in the part that supports the piezoelectric vibrator 100.

[0074] Furthermore, the actuator 10 does not use a relatively thick elastic adhesive as in the conventional technology, but instead fixes the piezoelectric vibrator 100 with highly rigid supports ST1 and ST2. This suppresses adverse effects on the vibration characteristics of the actuator 10 caused by the support mechanism of the piezoelectric vibrator 100. For example, when using an adhesive as in the conventional configuration, the thickness and volume of the adhesive increase, causing the adhesive and solvent to seep into the vibrator, adversely affecting the vibration characteristics. This also leads to variations in the shape of the adhesive, resulting in variations in vibration characteristics. However, in the actuator 10 according to the embodiment of the present invention, it is not necessary to use a thick adhesive as in the conventional technology, so the adverse effects caused by using such an adhesive can be suppressed.

[0075] Furthermore, the dimensions of the support ST1 described above should preferably satisfy the following dimensions.

[0076] (A1) The depth W(COV1) of the recess COV1 is between 1 / 10 and 3 / 5 of the width W(ST1) of the support ST1. (B1) The height H(COV1) of the recess COV1 is between 7 / 50 and 3 / 5 of the thickness H(ST1) of the support ST1. (C1) The distance D(AD1) of the recess COV1 from the surface FST12 (the contact surface between the support ST1 and the piezoelectric vibrator 100) is between 3 / 100 and 7 / 10 of the thickness H(ST1) of the support ST1. (D1) The volume V(COV1) of the recess COV1 is between 1 / 100 and 7 / 20 of the volume of the support ST1. By satisfying at least one of these conditions, the actuator 10 can properly maintain the strength of the support ST1 against the bending vibration of the piezoelectric vibrator 100 and relieve the stress caused by the bending vibration of the piezoelectric vibrator 100.

[0077] The dimensions of the support ST2 described above should preferably satisfy the following dimensions.

[0078] (A2) The depth W(COV2) of the recess COV2 is between 1 / 10 and 3 / 5 of the width W(ST2) of the support ST2. (B2) The height H(COV2) of the recess COV2 is between 7 / 50 and 3 / 5 of the thickness H(ST2) of the support ST2. (C2) The distance D(AD2) of the recess COV2 from the surface FST21 (the contact surface between the support ST2 and the piezoelectric vibrator 100) is between 3 / 100 and 7 / 10 of the thickness H(ST2) of the support ST2. (D2) The volume V(COV2) of the recess COV2 is between 1 / 100 and 7 / 20 of the volume of the support ST2. By satisfying at least one of these conditions, the actuator 10 can properly maintain the strength of the support ST2 against the bending vibration of the piezoelectric vibrator 100 and relieve the stress caused by the bending vibration of the piezoelectric vibrator 100.

[0079] [Second Embodiment] An actuator according to a second embodiment of the present invention will be described with reference to the figures. Figure 6 is a cross-sectional view showing a part of the actuator according to the second embodiment.

[0080] As shown in Figure 6, the actuator 10A according to the second embodiment differs from the actuator 10 according to the first embodiment in the shape of the recess formed in the support. The other components of the actuator 10A are the same as those of the actuator 10, and a description of the similar parts will be omitted.

[0081] The actuator 10A comprises a piezoelectric vibrator 100, a support ST1A, and a support ST2A.

[0082] Support ST1A includes a recess COV1A, and the presence of the recess COV1A provides a thin-walled portion TWP1A. The recess COV1A includes recesses COV11A and COV12A. Recesses COV11A and COV12A have different depths. In other words, recesses COV11A and COV12A each have bottom surfaces that are at different distances from the inner circumferential surface FiST1. Recess COV11A is deeper than recess COV12A.

[0083] The recess COV12A is formed on the side of surface FST12 (the side in contact with the piezoelectric vibrator 100) than the recess COV11A. The recesses COV11A and COV12A are aligned in the thickness direction of the support ST1A and are in communication with each other.

[0084] Support ST2A includes a recess COV2A, and the presence of the recess COV2A provides a thin-walled portion TWP2A. The recess COV2A comprises a recess COV21A and a recess COV22A. The recess COV21A and the recess COV22A differ in depth. In other words, the recess COV21A and the recess COV22A each have bottom surfaces that are at different distances from the inner circumferential surface FiST2. The recess COV21A is deeper than the recess COV22A.

[0085] The recess COV22A is formed on the side of surface FST21 (the side in contact with the piezoelectric vibrator 100) than the recess COV21A. The recesses COV21A and COV22A are aligned in the thickness direction of the support ST2A and are in communication with each other.

[0086] With this configuration, actuator 10A can achieve the same effects as actuator 10, and stress can be further reduced.

[0087] Furthermore, the number of locations with different depths is not limited to two; there may be three or more.

[0088] [Third Embodiment] An actuator according to a third embodiment of the present invention will be described with reference to the figures. Figure 7 is a cross-sectional view showing a part of the actuator according to the third embodiment.

[0089] As shown in Figure 7, the actuator 10B according to the third embodiment differs from the actuator 10 according to the first embodiment in the shape of the recess formed in the support. The other components of the actuator 10B are the same as those of the actuator 10, and a description of the similar parts will be omitted.

[0090] The actuator 10B comprises a piezoelectric vibrator 100, a support ST1B, and a support ST2B.

[0091] Support body ST1B includes a recess COV1B. Recess COV1B includes recesses COV11B and COV12B. Recesses COV11B and COV12B have the same depth. Support body ST1B includes a thin-walled portion TWP11B due to recess COV11B, and a thin-walled portion TWP12B due to recess COV12B.

[0092] The recess COV11B is formed on the side of surface FST12 (the side in contact with the piezoelectric vibrator 100) than the recess COV12B. The recesses COV11B and COV12B are aligned in the thickness direction of the support ST1B and are independent of each other. In this way, the support ST1B has two stages of recesses.

[0093] The support ST2B includes a recess COV2B. The recess COV2B includes a recess COV21B and a recess COV22B. The recesses COV21B and COV22B have the same depth. The support ST21B includes a thin-walled portion TWP21B due to the recess COV21B, and a thin-walled portion TWP22B due to the recess COV22B.

[0094] The recess COV21B is formed on the side of surface FST21 (the side in contact with the piezoelectric vibrator 100) than the recess COV22B. The recesses COV21B and COV22B are aligned in the thickness direction of the support ST2B and are independent of each other. In this way, the support ST2B has two stages of recesses.

[0095] With this configuration, actuator 10B can achieve the same effects as actuator 10, and stress can be further reduced.

[0096] Furthermore, the number of recesses is not limited to two; it may be three or more. Also, the shape of each recess may be the same or different.

[0097] [Fourth Embodiment] An actuator according to a fourth embodiment of the present invention will be described with reference to the figures. Figure 8 is a cross-sectional view showing a part of the actuator according to the fourth embodiment.

[0098] As shown in Figure 8, the actuator 10C according to the fourth embodiment differs from the actuator 10 according to the first embodiment in the shape of the recess formed in the support. The other components of the actuator 10C are the same as those of the actuator 10, and a description of the similar parts will be omitted.

[0099] The actuator 10C comprises a piezoelectric vibrator 100, a support ST1C, and a support ST2C. Support ST1C includes a recess COV1C. The bottom surface of the recess COV1C has a semicircular cross-sectional shape. Support ST2C includes a recess COV2C. The bottom surface of the recess COV2C has a semicircular cross-sectional shape. Support ST1C is provided with a thin-walled portion TWP1C by the recess COV1C, and with a thin-walled portion TWP2C by the recess COV2C.

[0100] With this configuration, actuator 10C can achieve the same effects as actuator 10.

[0101] Furthermore, as shown in actuator 10C, the shape of the bottom surface of the recess can be set as appropriate.

[0102] [Fifth Embodiment] An actuator according to a fifth embodiment of the present invention will be described with reference to the figures. Figure 9 is a cross-sectional view showing a part of the actuator according to the fifth embodiment.

[0103] The actuator 10D according to the fifth embodiment differs from the actuator 10 according to the first embodiment in that it has a unimorph structure. The other components of the actuator 10D are the same as those of the actuator 10, and a description of the similar parts will be omitted.

[0104] The actuator 10D includes a piezoelectric vibrator 100D. The piezoelectric vibrator 100D includes a piezoelectric element 21 and a plate member 31.

[0105] Support ST1 is connected to plate member 31. Support ST2 is connected to piezoelectric element 21.

[0106] With this configuration, actuator 10D can achieve the same effects as actuator 10. Furthermore, since actuator 10D has a unimorph structure, it can have fewer components than actuator 10, which has a bimorph structure, thus enabling a thinner design.

[0107] In the embodiments described above, we have shown a configuration in which a piezoelectric element without polarization reversal processing is used. However, it is also possible to use a piezoelectric element that has undergone polarization reversal processing.

[0108] Furthermore, in the embodiments described above, the outer edge of the piezoelectric vibrator and the outer edge of the support body are shown to coincide in a plan view. However, the outer edge of the piezoelectric vibrator and the outer edge of the support body do not have to coincide in a plan view. Also, the outer shape of the piezoelectric element and the outer shape of the plate member are such that the outer shape of the plate member is equal to or larger than the outer shape of the piezoelectric element. Moreover, the outer shapes of the plate member and the support body are not limited to circular shapes.

[0109] <1> A piezoelectric vibrator is composed of a laminate containing a plate member and a piezoelectric element, and has a first main surface and a second main surface facing each other. A first support having a ring shape and a predetermined thickness when viewed from above, Equipped with, The first support is, The ring-shaped inner and outer surfaces, and third and fourth surfaces connected to and facing each other, The third surface is fixed to the first main surface of the piezoelectric vibrator, An actuator having a thin-walled portion at an intermediate position between the third surface and the fourth surface in the thickness direction, where the distance between the inner circumferential surface and the outer circumferential surface is shortened by the inner circumferential surface being recessed.

[0110] <2> The thin-walled portion has an annular shape along the inner circumferential surface. <1> The actuator described above.

[0111] <3> The thin-walled portion is composed of a plurality of thin-walled portions arranged at different positions in the thickness direction. <1> or <2> The actuator described above.

[0112] <4> The thin-walled portion comprises a plurality of parts with different distances between the inner circumferential surface and the outer circumferential surface. <1> or <2> The actuator described above.

[0113] <5> A second support is provided, which is ring-shaped and has a predetermined thickness when viewed from above. The second support is The ring-shaped inner and outer surfaces, and the fifth and sixth surfaces connected to the inner and outer surfaces and facing each other, The fifth surface is fixed to the second main surface of the piezoelectric vibrator, At an intermediate position between the fifth and sixth surfaces in the thickness direction, there is a thin-walled portion formed by the inner circumferential surface being recessed, which shortens the distance between the inner circumferential surface and the outer circumferential surface. <1> ~ <4> An actuator as described in any of the following.

[0114] <6> Viewed in the direction in which the first support, the piezoelectric vibrator, and the second support are aligned, the inner surface of the first support and the inner surface of the second support overlap. <5> The actuator described above.

[0115] <7> Viewed in the direction in which the first support, the piezoelectric vibrator, and the second support are aligned, the thin-walled portion of the first support and the thin-walled portion of the second support overlap. <5> or <6> The actuator described above. [Explanation of Symbols]

[0116] 10, 10A, 10B, 10C, 10D: Actuators 21, 22: Piezoelectric element 31, 32, 33: Plate members 100, 100D: Piezoelectric vibrator 210, 220: Piezoelectric 211, 212, 221, 222: Driving electrodes COV1, COV11A, COV11B, COV12A, COV12B, COV1A, COV1B, COV1C, COV2, COV21A, COV21B, COV22A, COV22B, COV2A, COV2B, COV2C: recessed F211, F212, F221, F222, F311, F312, F321, F322: Surface FC1, FC2: Bottom FST11, FST12, FST21, FST22: Surface Fe21, Fe22, Fe31, Fe32, Fe33: outer edge FeST1, FeST2: Outer surface FiST1, FiST2: Inner surface FsC11, FsC12, FsC21, FsC22: Side view PAD1, PAD2: End points Po, Po21, Po22, Po31, Po32, Po33: Center point ST1, ST1A, ST1B, ST1C, ST2, ST2A, ST2B, ST2C: Support TWP1, TWP1A, TWP11B, TWP12B, TWP1C, TWP2, TWP2A, TWP21B, TWP22B, TWP2C: Thin section

Claims

1. A piezoelectric vibrator is composed of a laminate containing a plate member and a piezoelectric element, and has a first main surface and a second main surface facing each other, A first support having a ring shape and a predetermined thickness when viewed from above, Equipped with, The first support is The ring-shaped inner and outer surfaces, and the third and fourth surfaces connected to and facing each other, The third surface is fixed to the first main surface of the piezoelectric vibrator, A thin-walled portion is provided at a position between the third surface and the fourth surface in the thickness direction, where the inner circumferential surface is recessed, thereby shortening the distance between the inner circumferential surface and the outer circumferential surface. Actuator.

2. The thin-walled portion has an annular shape along the inner circumferential surface. The actuator according to claim 1.

3. The thin-walled portion is composed of a plurality of thin-walled portions arranged at different positions in the thickness direction. The actuator according to claim 1.

4. The thin-walled portion comprises a plurality of parts with different distances between the inner circumferential surface and the outer circumferential surface. The actuator according to claim 1.

5. A second support is provided, which is ring-shaped and has a predetermined thickness when viewed from above. The second support is, The ring-shaped inner and outer surfaces, and the fifth and sixth surfaces connected to and facing each other, The fifth surface is fixed to the second main surface of the piezoelectric vibrator, At an intermediate position between the fifth and sixth surfaces in the thickness direction, there is a thin-walled portion formed by the inner circumferential surface being recessed, which shortens the distance between the inner circumferential surface and the outer circumferential surface. The actuator according to claim 1.

6. Viewed in the direction in which the first support, the piezoelectric vibrator, and the second support are aligned, the inner surface of the first support and the inner surface of the second support overlap. The actuator according to claim 5.

7. Viewed in the direction in which the first support, the piezoelectric vibrator, and the second support are aligned, the thin-walled portion of the first support and the thin-walled portion of the second support overlap. The actuator according to claim 5.

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