Actuator

Abstract

This reduces the stress at the bonding point between the diaphragm and the support. [Solution] The actuator 10 comprises a piezoelectric vibrator 100 and a support ST1. The piezoelectric vibrator 100 comprises a plate member 31 having two opposing surfaces F311 and F312, and a piezoelectric element positioned on surface F312. The support ST1 is ring-shaped in plan view. In plan view, the support ST1 comprises an inner circumferential surface FiST1 and an outer circumferential surface FeST1, respectively, and surfaces FST11 and FST12 connecting the inner circumferential surface FiST1 and the outer circumferential surface FeST1. One surface FST11 of the support ST1 is bonded to the plate member 31. The plate member 31 comprises a thin-walled portion 31TN. The thin-walled portion 31TN is ring-shaped, with surface F311 recessed toward surface F312, and has an inner circumferential end IEC and an outer circumferential end OEC. In the thickness direction of the plate member 31, the outer circumferential end OEC of the thin-walled portion 31TN and the inner circumferential surface FiST1 of the support ST1 overlap.

Description

Technical Field

[0001] The present invention relates to an actuator including a piezoelectric vibrator and a support for supporting the piezoelectric vibrator.

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 Document

Patent Document

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the configuration of Patent Document 1, stress generated during vibration of the diaphragm concentrates on the fixing portion, and there is a possibility of breakage between the diaphragm and the fixing portion.

[0005] Therefore, an object of the present invention is to reduce stress generated between the diaphragm and the fixing portion.

Means for Solving the Problems

[0006] An actuator according to one embodiment of this invention comprises a piezoelectric vibrator and a support. The piezoelectric vibrator comprises a plate member having a first surface and a second surface facing each other, and a piezoelectric element disposed on the second surface. The support is ring-shaped in plan view. In plan view, the support comprises an inner circumferential surface and an outer circumferential surface, each ring-shaped, and an end surface connecting the inner circumferential surface and the outer circumferential surface. One end surface of the support is bonded to the plate member. The plate member comprises a thin-walled portion. The thin-walled portion is ring-shaped, with the first surface recessed toward the second surface, and has an inner end and an outer end. In the thickness direction of the plate member, the outer end of the thin-walled portion and the inner circumferential surface of the support overlap.

[0007] In this configuration, the stress at the point where the plate member and the support are bonded is distributed to the thin-walled portion. As a result, the stress at the point where the plate member and the support are bonded is reduced. [Effects of the Invention]

[0008] According to this invention, the stress generated between the diaphragm and the support can be reduced. [Brief explanation of the drawing]

[0009] [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] Figure 3(A) is a cross-sectional view showing a part of the actuator according to the first embodiment, and Figure 3(B) is a partially enlarged view of Figure 3(A). [Figure 4] Figure 4(A) is a cross-sectional view of the plate member, and Figure 4(B) is a partially enlarged cross-sectional view of the plate member. [Figure 5] Figure 5(A) shows an example of the stress distribution on the actuator according to the first embodiment, and Figure 5(B) shows an example of the stress distribution due to vibration on the actuator of the comparative example. [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. [Modes for carrying out the invention]

[0010] [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. Figure 3(A) is a cross-sectional view showing a part of the actuator according to the first embodiment, and Figure 3(B) is a partially enlarged view of Figure 3(A). Figure 3(A) shows one outer edge (support) side from the center of the actuator.

[0011] Note that the black circles indicating points (e.g., the center) in each figure 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 component.

[0012] As shown in Figures 1, 2, 3(A), and 3(B), the actuator 10 comprises a piezoelectric vibrator 100 and a support ST1. The piezoelectric vibrator 100 comprises a piezoelectric element 21, a piezoelectric element 22, a plate member 31, a plate member 32, and a plate member 33.

[0013] 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.

[0014] 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.

[0015] 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 electrode 211 and the drive electrode 212 are in a shape that overlaps in plan view.

[0016] The drive electrode 211 and the drive electrode 212 are thin films, for example, thinner than the thickness of the piezoelectric body 210. The drive electrode 211 and the drive electrode 212 are formed, for example, by vapor deposition treatment, sputtering treatment, or the like on the surfaces F211 and F212 of the piezoelectric body 210. The drive electrode 211 and the drive electrode 212 are electrodes for the purpose of applying a voltage to the piezoelectric body 210.

[0017] 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.

[0018] 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.

[0019] 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 electrode 221 and the drive electrode 222 are in a shape that overlaps in plan view.

[0020] The drive electrode 221 and the drive electrode 222 are thin films, for example, thinner than the thickness of the piezoelectric body 220. The drive electrode 221 and the drive electrode 222 are formed, for example, by vapor deposition treatment, sputtering treatment, or the like on the surfaces F221 and F222 of the piezoelectric body 220. The drive electrode 221 and the drive electrode 222 are electrodes for the purpose of applying a voltage to the piezoelectric body 220.

[0021] 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. 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. Surface F311 corresponds to the "first surface" of the present invention, and surface F312 corresponds to the "second surface" of the present invention.

[0022] 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. 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.

[0023] The plate member 33 is made of metal and is a disc. The plate member 33 has an outer edge Fe 33.

[0024] The piezoelectric elements 21, 22, plate members 31, 32, and 33 are stacked as follows to constitute the piezoelectric vibrator 100.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] In this case, when viewed from above (viewed in the stacking direction), the center Po31 of plate member 31, the center Po21 of piezoelectric element 21, the center Po33 of plate member 33, the center Po22 of piezoelectric element 22, and the center Po32 of plate member 32 overlap (contend). Here, overlap (contend) means that a range of manufacturing tolerances, including assembly errors, is permitted.

[0030] By stacking the piezoelectric elements 21, 22, plate member 31, 32, and 33 in this manner, the piezoelectric vibrator 100 achieves a bimorph structure.

[0031] The support ST1 is made of a highly rigid material such as metal. The support ST1 has an annular shape when viewed from above. 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.

[0032] The support ST1 has a surface FST11, which is an annular plane, at one end in the thickness direction. The support ST1 has a surface FST12, which is an annular plane, at the other end in the thickness direction. Surfaces FST11 and FST12 are connected to the inner circumferential surface FiST1 and the outer circumferential surface FeST1. FST11 and FST12 correspond to the end faces of the support ST1.

[0033] The piezoelectric vibrator 100 is fixed and supported by the support ST1. More specifically, the surface FST12 of the support ST1 is bonded to the surface F311 of the plate member 31 on the piezoelectric vibrator 100. In this case, when viewed in the direction in which the piezoelectric vibrator 100 and the support ST1 are aligned, the center Po31 of the plate member 31 and the center of the circle formed by the inner circumferential surface FiST1 of the support ST1 coincide.

[0034] 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 piezoelectric vibrator 100, and for example, they are approximately the same as the resonant frequency of the piezoelectric vibrator 100.

[0035] Thus, when the first and second drive signals are supplied, the piezoelectric elements 21 and 22 undergo contraction strain. The plate members 31 and 32 vibrate in a flexing manner due to this contraction strain. In other words, the plate members 31 and 32 function as diaphragms. The piezoelectric vibrator 100 vibrates in a region inside the part that is bonded and fixed to the support ST1. The flexing vibration is a vibration that displaces in a direction parallel to the lamination direction, and the point of maximum displacement of this flexing vibration approximately coincides with the center Po of the region of the piezoelectric vibrator 100 that is not fixed by the support ST1 (the region inside the inner circumferential surface FiST1 of the support ST1 in a plan view).

[0036] In such an actuator 10, the plate member 31 further comprises the following configuration. Figure 4(A) is a cross-sectional view of the plate member, and Figure 4(B) is a partially enlarged cross-sectional view of the plate member. Figure 4(A) is a cross-sectional view taken by a plane passing through the center of the plate member.

[0037] As shown in Figures 4(A) and 4(B), the plate member 31 is provided with a recess COV. The recess COV is recessed from the surface F311. The recess COV is annular in shape and, when viewed in a direction perpendicular to the surface F311, has a circular outer circumferential end OEC and an inner circumferential end IEC.

[0038] The cross-sectional shape of the recessed COV, when cut by a plane perpendicular to the direction of extension of the annular shape, is approximately semicircular. In other words, the recessed COV has no corners except for the ends that connect to the outer peripheral edge OEC and the inner peripheral edge IEC.

[0039] Furthermore, the shape of the concave COV is not limited to this; the cross-sectional shape obtained by cutting with a plane perpendicular to the direction of extension of the annular shape may be a rectangle with rounded corners. Also, the cross-sectional shape obtained by cutting with a plane perpendicular to the direction of extension of the annular shape may be a rectangle with corners.

[0040] The recessed area (COV) has a depth DCOV. This depth DCOV corresponds to the depth of the deepest part of the recessed area (COV).

[0041] The plate member 31 has a thin-walled portion 31TN due to having such a recessed COV.

[0042] The thin-walled portion 31TN overlaps with the formation region of the recessed COV when viewed in a direction perpendicular to surfaces F311 and F312. The portion of surface F312 corresponding to the thin-walled portion 31TN is flush with the other portions of surface F312. Flushness means that the positions in the thickness direction of the plate member 31 are the same. Furthermore, the portion of surface F311 corresponding to the thin-walled portion 31TN is shorter relative to surface F312 than the other portions of surface F311.

[0043] The thin-walled portion 31TN has a curved shape that is recessed toward the surface F312 when the plate member 31 is viewed from the side, due to the configuration of the recessed COV described above. Because the thin-walled portion 31TN does not have corners in this way, damage to the plate member 31 can be suppressed when stress described later is applied. The shape of the thin-walled portion 31TN can be various shapes, corresponding to the types of shapes of the recessed COV described above.

[0044] The piezoelectric vibrator 100, which has a plate member 31 of this shape, is bonded to the support ST1 as shown in Figures 3(A) and 3(B).

[0045] When viewed in the direction in which the piezoelectric vibrator 100 and the support ST1 are aligned, the outer peripheral edge OEC of the recess COV of the plate member 31 and the inner peripheral surface FiST1 of the support ST1 overlap. More specifically, the outer peripheral edge OEC of the recess COV of the plate member 31 and the inner peripheral surface FiST1 of the support ST1 overlap over the entire circumference of the annular shape. In this invention, including as described herein, "overlapping" includes within the range of manufacturing tolerances. For example, when the outer peripheral edge OEC of the recess COV and the inner peripheral surface FiST1 of the support ST1 overlap, it is preferable that the outer peripheral edge OEC coincides with the inner peripheral surface FiST1.

[0046] However, the outer edge OEC may be shifted within a predetermined range from the inner surface FiST1 towards the outer surface FeST1, or the outer edge OEC may be shifted within a predetermined range towards the center of the piezoelectric vibrator 100 from the inner surface FiST1. In this case, the predetermined range of the shift, if on the outer surface FeST1 side, is the range in which the reduction in bonding strength between the piezoelectric vibrator 100 and the support ST1 can ensure the reliability required for the actuator 10. On the other hand, if the predetermined range of the shift, if on the center side of the piezoelectric vibrator 100, is the range in which the location of the maximum stress, described later, does not involve the corner PAD (the inner end of the surface where the plate member 31 and the support ST1 are bonded).

[0047] However, when viewed in the direction in which the piezoelectric vibrator 100 and the support ST1 are aligned, it is preferable that the outer peripheral end OEC of the recess COV of the plate member 31 is not positioned outside the inner peripheral surface FiST1 of the support ST1. That is, when viewed in the direction in which the piezoelectric vibrator 100 and the support ST1 are aligned, it is preferable that the outer peripheral end OEC of the recess COV is not positioned between the inner peripheral surface FiST1 and the outer peripheral surface FeST1 of the support ST1.

[0048] With this configuration, a recessed area (COV) is formed on the side of the piezoelectric vibrator 100 that adheres to the support ST1 (the surface F311 of the plate member 31), along the inner circumferential surface FiST1 of the support ST1.

[0049] In other words, the thin-walled portion 31TN of the piezoelectric vibrator 100 is positioned along the inner circumferential surface FiST1 of the support ST1. The side of the thin-walled portion 31TN that adheres to the support ST1 is located closer to the center in the thickness direction of the piezoelectric vibrator 100 than the other parts, and is adhered to the piezoelectric element 21 across its surface.

[0050] In an actuator 10 with this configuration, when the piezoelectric vibrator 100 vibrates, stress is applied to the bonding portion between the piezoelectric vibrator 100 and the support ST1.

[0051] Figure 5(A) shows an example of the stress distribution applied to the actuator according to the first embodiment, and Figure 5(B) shows an example of the stress distribution due to vibration applied to the actuator of the comparative example. The comparative example is configured without the recessed COV (thin-walled portion 31TN) compared to the actuator 10 according to this embodiment. Figures 5(A) and 5(B) show that the darker the hatching, the greater the stress applied.

[0052] First, as shown in Figure 5(B), in the comparative example, the stress due to the bending vibration of the piezoelectric vibrator 100 extends towards the plate member 31, including the inner corner PAD on the surface where the plate member 31 and the support ST1 are bonded. The location of the maximum stress is at the corner PAD and its vicinity. This location is the edge of the surface where the plate member 31 and the support ST1 are bonded, and is a place where stress is likely to cause fracture of the bonded surface between the plate member 31 and the support ST1.

[0053] On the other hand, as shown in Figure 5(A), the actuator 10 has a recessed COV (thin-walled portion 31TN), so the location of the maximum stress is the thin-walled portion 31TN. Consequently, the stress at the corner PAD where the plate member 31 and the support ST1 are bonded is reduced. This is thought to be because the thin-walled portion 31TN has lower rigidity than other parts of the plate member 31, making it more susceptible to stress.

[0054] In this way, the actuator 10 can reduce vibration-induced stress at locations prone to fracture of the adhesive surface between the plate member 31 and the support ST1. Therefore, the actuator 10 can reduce stress at the adhesive site between the piezoelectric vibrator 100 and the support ST1. As a result, the reliability of the actuator 10 can be improved.

[0055] In this case, even if the plate member 31 is provided with a recessed COV (thin-walled portion 31TN), the actuator 10 hardly dampens the bending vibration of the piezoelectric vibrator 100. As a specific example, simulation results show that the actuator 10 can reduce the stress on the corner PAD by about 80% compared to the comparative example, while maintaining the maximum displacement due to bending vibration at about 98% (keeping the damping rate at about 2%).

[0056] In this way, the actuator 10 can reduce the stress on the bonding site between the piezoelectric vibrator 100 and the support ST1, thereby improving reliability and suppressing the deterioration of vibration performance.

[0057] Furthermore, the shapes of the aforementioned recessed COV and thin-walled portion 31TN are preferable if they satisfy the following conditions, for example.

[0058] (A) The depth DCOV of the recess COV is 2 / 3 or less of the thickness D31 of the plate member 31 (thickness of the portion other than the recess COV formation portion) (see Figure 4(B)). In other words, the thickness of the thin portion 31TN is 1 / 3 or more of the thickness D31 of the plate member 31 (thickness of the portion other than the thin portion 31TN).

[0059] (B) The width WCOV of the recessed COV (width W31TN of the thin-walled portion 31TN) is less than or equal to the thickness D31 of the plate member 31 (thickness of the portion other than the recessed COV formation portion (thin-walled portion 31TN)).

[0060] By satisfying at least one of these conditions, the actuator 10 can more reliably achieve the effects of improving reliability and suppressing the deterioration of vibration performance.

[0061] In the above explanation, it was shown that the overlap between the outer peripheral edge OEC of the recess COV of the plate member 31 and the inner peripheral surface FiST1 of the support ST1 may include, for example, manufacturing tolerances. More specifically, when the distance from the center Po31 of the plate member 31 to the inner peripheral surface FiST1 of the support ST1 is set to 1, it is preferable that the distance (amount of deviation) between the outer peripheral edge OEC of the recess COV (thin-walled portion 31TN) and the inner peripheral surface FiST1 of the support ST1 is 9 / 100 or less.

[0062] As a result, the actuator 10 can more reliably achieve the effects of improving reliability and suppressing the deterioration of vibration performance.

[0063] [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.

[0064] As shown in Figure 6, the actuator 10A according to the second embodiment differs from the actuator 10 according to the first embodiment in that it includes an adhesive 40. 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.

[0065] The actuator 10A is equipped with an adhesive 40. The adhesive 40 is made of a material with a lower modulus of elasticity than the plate member 31. The adhesive 40 is filled into the recessed COV. In other words, the adhesive 40 is positioned to overlap the thin-walled portion 31TN.

[0066] With this configuration, the actuator 10A, like the actuator 10, can reduce the stress at the bonding point between the piezoelectric vibrator 100 and the support ST1.

[0067] The adhesive 40 can be composed of the adhesive used to bond the plate member 31 and the support ST1. When the plate member 31 and the support ST1 are bonded, the adhesive 40 that flows to the inner circumferential surface FiST1 side of the support ST1 fills the recessed COV, thereby realizing the above-described configuration. This configuration suppresses the flow of the adhesive 40 towards the center of the piezoelectric vibrator 100 beyond the recessed COV, thereby suppressing deterioration of the vibration characteristics.

[0068] [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.

[0069] As shown in Figure 7, the actuator 10B according to the third embodiment differs from the actuator 10A according to the second embodiment in the area where the adhesive 40 is placed. The other components of the actuator 10B are the same as those of the actuator 10A, and a description of the similar parts will be omitted.

[0070] In actuator 10B, the adhesive 40 fills the recessed COV and protrudes outward from the surface F311 of the plate member 31 to the inner circumferential surface FiST1 of the support ST1. In other words, the adhesive 40 spreads from the recessed COV to the inner circumferential surface FiST1. At this time, the adhesive 40 covers the corner PAD.

[0071] With this configuration, actuator 10B, like actuator 10A, can reduce the stress on the bonding surface between the piezoelectric vibrator 100 and the support ST1. Furthermore, because the corner PAD of actuator 10B is covered with adhesive 40, fracture of the bonding surface between the piezoelectric vibrator 100 and the support ST1 can be made less likely.

[0072] [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.

[0073] As shown in Figure 8, the actuator 10C according to the fourth embodiment differs from the actuator 10 according to the first embodiment in that it includes a support ST2 and in the configuration of the plate member 32. 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.

[0074] The actuator 10C includes a support ST2. The support ST2 has the same configuration as the support ST1. In plan view, the support ST2 has a circular inner surface FiST2 and an outer surface FeST2. The support ST2 has a surface FST21, which is an annular plane, at one end in the thickness direction. The support ST2 has a surface FST22, which is an annular plane, at the other end in the thickness direction. Surfaces FST21 and FST22 are connected to the inner surface FiST2 and the outer surface FeST2.

[0075] The surface FST22 of the support ST2 is bonded to the surface F321 of the plate member 32 on the piezoelectric vibrator 100. In this case, when viewed in the direction in which the piezoelectric vibrator 100 and the support ST2 are aligned, the center Po32 of the plate member 32 and the center of the circle formed by the inner circumferential surface FiST2 of the support ST2 coincide.

[0076] Furthermore, when viewed in the direction in which the support ST1, piezoelectric vibrator 100, and support ST2 are aligned, support ST1 and support ST2 overlap. In this case, the inner surface FiST1 of support ST1 and the inner surface FiST2 of support ST2 overlap.

[0077] The plate member 32 has a recessed area (COV) that is recessed from the surface F321. The plate member 32 has a thin-walled portion 32TN in the region that overlaps with the recessed area (COV).

[0078] When viewed in a direction perpendicular to the surface F311 of plate member 31 and the surface F321 of plate member 32 in the piezoelectric vibrator 100, the recess COV of plate member 31 and the recess COV of plate member 32 overlap. In other words, the thin-walled portion 31TN of plate member 31 and the thin-walled portion 32TN of plate member 32 overlap.

[0079] When viewed in the direction in which the piezoelectric vibrator 100 and the support ST2 are aligned, the outer peripheral edge OEC of the recess COV of the plate member 32 and the inner peripheral surface FiST2 of the support ST2 overlap.

[0080] With this configuration, the actuator 10C can achieve a configuration in which the piezoelectric vibrator 100 is sandwiched between the support ST1 and the support ST2, while reducing the stress at the bonding points between the piezoelectric vibrator 100 and the support ST1, and the stress at the bonding points between the piezoelectric vibrator 100 and the support ST2.

[0081] Furthermore, the configuration of the fourth embodiment can be combined with the configurations of the second and third embodiments.

[0082] 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.

[0083] Furthermore, although the embodiments described above show the use of a piezoelectric vibrator with a bimorph structure, it is also possible to use a piezoelectric vibrator with a unimorph structure.

[0084] 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. [Explanation of Symbols]

[0085] 10, 10A, 10B, 10C: Actuators 21, 22: Piezoelectric element 31, 32, 33: Plate members 31TN, 32TN: Thin wall part 40: Adhesive 100: Piezoelectric vibrator 210, 220: Piezoelectric 211, 212, 221, 222: Electrodes for moving COV: concavity F211, F212, F221, F222, F311, F312, F321, F322, FST11, FST12, FST21, FST22: Surface Fe21, Fe22, Fe31, Fe32, Fe33: external FeST1, FeST2: Outer peripheral surface FiST1, FiST2: Inner circumferential surface IEC: Inner Perimeter OEC: Peripheral end PAD: Corner Po, Po21, Po22, Po31, Po32, Po33: center ST1, ST2: Support body

Claims

1. A piezoelectric vibrator comprising a plate member having a first surface and a second surface facing each other, and a piezoelectric element disposed on the second surface, When viewed from above, it has a ring-shaped support structure, Equipped with, The support comprises an inner circumferential surface and an outer circumferential surface that are ring-shaped in plan view, and an end surface connecting the inner circumferential surface and the outer circumferential surface. One of the end faces of the support is bonded to the plate member. The plate member has a thin portion, The thin-walled portion has an annular shape in which the first surface is recessed toward the second surface, and has an inner circumferential end and an outer circumferential end. Viewed in the thickness direction of the plate member, the outer peripheral end of the thin portion and the inner peripheral surface of the support overlap. Actuator.

2. The recess, which has the aforementioned concave shape, is filled with adhesive. The actuator according to claim 1.

3. The adhesive protrudes from the first surface and is arranged to extend continuously onto the inner circumferential surface. The actuator according to claim 2.

4. The elastic modulus of the adhesive is lower than that of the plate member. The actuator according to claim 2.

5. The portion of the first surface corresponding to the thin-walled portion has a curved shape that is recessed toward the second surface when the plate member is viewed from the side. The actuator according to any one of claims 1 to 4.

6. The thickness of the thin portion is 1 / 3 or more and less than 1 of the thickness of the portion of the plate member other than the thin portion. The actuator according to any one of claims 1 to 5.

7. The distance between the inner and outer edges of the thin-walled portion is less than or equal to the thickness of the portion of the plate member other than the thin-walled portion. The actuator according to any one of claims 1 to 6.

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