Actuator

Abstract

An actuator (10) comprises a piezoelectric element (21), a plate member (31), and a support body (ST1). The piezoelectric element (21) has a surface (F211) and a surface (F212) facing each other. The plate member (31) has a surface (F311) and a surface (F312) facing each other, and the surface (F312) is disposed on the surface (F211). The plate member (31) is fixed to the support body (ST1) within a predetermined distance range in a direction from the outer edges of the surface (F311) and the surface (F312) toward the inside. The inner peripheral surface (FiST1) of the support body (ST1) is circular. The plate member (31) is provided with a slot (313). The slot (313) is disposed at a position closer to the center of the plate member (31) than a portion fixed to the support body (ST1). The slot (313) is configured from a recess that is recessed from the surface (F311) or the surface (F312), or a penetration part that penetrates between the surface (F311) and the surface (F312).

Description

Actuator

[0001] The present invention relates to an actuator having a laminated structure of a piezoelectric element and a plate member.

[0002] Patent Document 1 describes a piezoelectric pump. The piezoelectric pump of Patent Document 1 includes a circular piezoelectric element and a coating material.

[0003] The outer peripheral portion of the piezoelectric element covered by the coating material is supported by an outer container.

[0004] Japanese Patent Laid-Open No. 10-220357

[0005] As shown in Patent Document 1, in a configuration in which the outer peripheral portion of the piezoelectric element is supported, mechanical loss occurs in the support portion, and the vibration displacement decreases.

[0006] Therefore, an object of the present invention is to suppress a decrease in vibration displacement in a configuration for supporting the outer peripheral portion of a piezoelectric element.

[0007] An actuator according to an embodiment of this invention includes a first piezoelectric element, a first plate member, and a first support. The first piezoelectric element has a first surface and a second surface facing each other. The first plate member has a third surface and a fourth surface facing each other, and the fourth surface is disposed on the first surface. The first support is annular.

[0008] The first plate member is fixed to the first support in a predetermined distance range in a direction from the outer edges of the third surface and the fourth surface toward the inside.

[0009] The inner peripheral surface of the first support is circular. The first plate member includes a first slot. The first slot is disposed at a position closer to the center of the first plate member than the portion fixed to the first support. The first slot is composed of a recess recessed from the third surface or the fourth surface, or a through portion penetrating between the third surface and the fourth surface.

[0010] In this configuration, in the laminate of the first piezoelectric element and the first plate member, in the portion inward from the fixing portion fixed by the first support near the outer edge, there are parts where the thickness of the first plate member is thin or where the first member is absent. These parts are more easily deformed than other parts where the first piezoelectric element and the first plate member overlap. Consequently, the bending vibration of the laminate becomes larger.

[0011] According to this invention, the reduction in vibration displacement can be suppressed in a configuration that supports the outer periphery of a piezoelectric element.

[0012] Figure 1 is an exploded perspective view of the actuator according to the first embodiment. Figure 2 is an exploded perspective view of the actuator according to the first embodiment. Figure 3(A) is a perspective view of the plate member, Figure 3(B) is a plan view of the plate member, and Figure 3(C) is a cross-sectional view of the plate member. Figures 4(A) and 4(B) are cross-sectional views showing a part of the actuator according to the first embodiment. Figure 5(A) is a diagram schematically showing the difference in amplitude between the present configuration and a comparative configuration, and Figure 5(B) is a diagram simply showing the relationship between the slot and the polarization reversal position with respect to Figure 5(A). Figure 6 is an exploded perspective view of the actuator according to the second embodiment. Figure 7 is an exploded perspective view of the actuator according to the third embodiment. Figure 8 is an exploded perspective view of the actuator according to the fourth embodiment. Figures 9(A) and 9(B) are plan views showing derivative forms of the slot, respectively. Figures 10(A), 10(B), 10(C), and 10(D) are cross-sectional views showing derivative forms of the slot.

[0013] [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 perspective view of the plate member, Figure 3(B) is a plan view of the plate member, and Figure 3(C) is a cross-sectional view of the plate member. The cross-sectional view of Figure 3(C) shows the A-A section shown in Figure 3(B). 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 part) from the center of the actuator.

[0014] The center of the actuator is a point equidistant from the inner circumferential surface of support ST1 or ST2.

[0015] Note that the black circles representing points (for example, the center point) in each diagram represent geometric positions and do not need to be physically visible objects.

[0016] Furthermore, in the following explanation, viewing each component constituting the actuator 10 in the stacking direction will be referred to as a plan view of each conceptual element.

[0017] 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, and a plate member 33.

[0018] 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.

[0019] Surfaces F211 and F212 are circular when viewed in a direction perpendicular to each other (in a plan view). Surfaces F211 and F212 face each other. Surface F211 corresponds to the first surface. Surface F212 corresponds to the second surface. The outer edge Fe21 is circular when viewed in a plan view.

[0020] The piezoelectric element 210 has undergone polarization reversal processing. Specifically, as shown in Figures 4(A) and 4(B), the piezoelectric element 210 undergoes polarization reversal at a predetermined distance from the center point Po (which coincides with the center point PO21 of the piezoelectric element 210) toward the outer edge Fe21. When viewed from above, the polarization reversal positions Ppr are distributed in a circular pattern centered on the center point Po (center point PO21).

[0021] The driving electrode 211 is positioned on the surface F211. The driving electrode 211 comprises a central portion and an annular portion. In plan view, the central portion is circular. The annular portion is an annular shape positioned to surround the central portion. In plan view, the annular portion is divided into two approximately semicircular parts. Between the central portion and the annular portion, there is a non-electrode-formed area. In plan view, the non-electrode-formed area of ​​the driving electrode 211 coincides with the polarization reversal position Ppr.

[0022] The driving electrode 212 is positioned on the surface F212. The driving electrode 212 comprises a central portion and an annular portion. In plan view, the central portion is circular. The annular portion is an annular shape positioned to surround the central portion. In plan view, the annular portion is divided into two approximately semicircular parts. Between the central portion and the annular portion, there is a non-electrode-formed area. In plan view, the non-electrode-formed area of ​​the driving electrode 212 coincides with the polarization reversal position Ppr.

[0023] The driving electrodes 211 and 212 have overlapping shapes in a plan view. More specifically, the central parts of the driving electrode 211 and the central parts of the driving electrode 212 overlap in a plan view. The annular portion of the driving electrode 211 and the annular portion of the driving electrode 212 overlap in a plan view.

[0024] The driving electrodes 211 and 212 are thin films, for example, thinner than the thickness of the piezoelectric body 210. The driving electrodes 211 and 212 are formed, for example, by deposition on surfaces F211 and F212 of the piezoelectric body 210.

[0025] The driving electrodes 211 and 212 are electrodes intended to apply voltage to the piezoelectric element 210. In other words, the driving electrodes 211 and 212 do not have the function of generating bending vibrations of the actuator 10 by utilizing the strain of the piezoelectric element 210.

[0026] The piezoelectric element 22 has the same configuration as the piezoelectric element 21.

[0027] The piezoelectric element 22 comprises a piezoelectric body 220, a driving electrode 221, and a driving electrode 222. The piezoelectric body 220 is a disc. The piezoelectric body 220 has a surface F221, a surface F222, and an outer edge Fe22.

[0028] Surfaces F221 and F222 are circular when viewed in a direction perpendicular to each other (in a plan view). Surfaces F221 and F222 face each other. Surface F221 corresponds to the fifth surface, and surface F222 corresponds to the sixth surface. The outer edge Fe22 is circular when viewed in a plan view.

[0029] The piezoelectric element 220 has undergone polarization reversal processing. Specifically, as shown in Figures 4(A) and 4(B), the piezoelectric element 220 undergoes polarization reversal at a predetermined distance from the center point Po (which coincides with the center point PO22 of the piezoelectric element 220) toward the outer edge Fe22. When viewed from above, the polarization reversal positions Ppr are distributed in a circular pattern centered on the center point Po (center point PO22).

[0030] The driving electrode 221 is positioned on the surface F221. The driving electrode 221 comprises a central portion and an annular portion. In plan view, the central portion is circular. The annular portion is an annular shape positioned to surround the central portion. In plan view, the annular portion is divided into two approximately semicircular parts. Between the central portion and the annular portion, there is a non-electrode-formed area. In plan view, the non-electrode-formed area of ​​the driving electrode 221 coincides with the polarization reversal position Ppr.

[0031] The driving electrode 222 is positioned on the surface F222. The driving electrode 222 comprises a central portion and an annular portion. In plan view, the central portion is circular. The annular portion is an annular shape positioned to surround this central portion. In plan view, the annular portion is divided into two approximately semicircular parts. Between the central portion and the annular portion, there is a non-electrode-formed area. In plan view, the non-electrode-formed area of ​​the driving electrode 222 coincides with the polarization reversal position Ppr.

[0032] The driving electrodes 221 and 222 have overlapping shapes in a plan view. More specifically, the central parts of the driving electrode 221 and the central parts of the driving electrode 222 overlap in a plan view. The annular portion of the driving electrode 221 and the annular portion of the driving electrode 222 overlap in a plan view.

[0033] 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, for example, by deposition on surfaces F221 and F222 of the piezoelectric body 220.

[0034] The driving electrodes 221 and 222 are electrodes intended to apply voltage to the piezoelectric element 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 element 220.

[0035] 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.

[0036] 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. Surface F311 corresponds to the third surface, and surface F312 corresponds to the fourth surface. The outer edge Fe31 is circular when viewed in a plan view.

[0037] The plate member 31 is provided with a slot 313. In plan view, the slot 313 is an annular shape centered on the center point Po 31 of the plate member 31. The slot 313 has a predetermined width in the direction from the center point Po 31 toward the outer edge Fe 31. The slot 313 is composed of a through portion that penetrates between the plate member 31 and surfaces F311 and F312.

[0038] In plan view, slot 313 is composed of multiple partial slots, each of which is semi-circular in shape. These partial slots are arranged at equal intervals in the circumferential direction of the annular shape of slot 313. In other words, the multiple partial slots are arranged point-symmetrically with respect to the center point Po 31 of the plate member 31.

[0039] Multiple beam sections 314 are formed between multiple partial slots. The multiple beam sections 314 have a shape that extends radially from the center point Po 31 toward the outer edge Fe 31 and are in the shape of a predetermined width.

[0040] This slot 313 divides the plate member 31 into a central region 311 on the side of the slot 313 towards the center point Po 31, and an outer edge region 312 on the side of the slot 313 towards the outer edge Fe 31.

[0041] The wall surface on the central region 311 side forming the slot 313 (through portion) is the wall surface Fo11, and the wall surface on the outer edge region 312 side is the wall surface Fi12. Hereinafter, the wall surface Fo11 is referred to as the inner wall surface Fo11 of the slot 313, and the wall surface Fi12 is referred to as the outer wall surface Fi12 of the slot 313.

[0042] 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.

[0043] The surfaces F321 and F322 are circular when viewed in a direction perpendicular to each other (in plan view). The surface F321 and the surface F322 face each other. The surface F321 corresponds to the seventh surface, and the surface F322 corresponds to the eighth surface. The outer edge Fe32 is circular in plan view.

[0044] The plate member 32 includes a slot 323. In plan view, the slot 323 is in an annular shape centered on the center point Po32 of the plate member 32. Note that the annular shape in this embodiment is not a completely continuous annular shape but has a break in the circumferential direction. The slot 323 has a predetermined width in the direction from the center point Po32 toward the outer edge Fe32. The slot 323 is composed of a through portion that penetrates between the plate member 32, the surface F321, and the surface F322.

[0045] The slot 323 is composed of a plurality of partial slots each having a semi-annular shape (arc shape) in plan view. The plurality of partial slots are arranged at equal intervals in the circumferential direction of the annular shape of the slot 323. In other words, the plurality of partial slots are arranged point-symmetrically with respect to the center point Po32 of the plate member 32.

[0046] Between the plurality of partial slots, a plurality of beam portions 324 are formed. The plurality of beam portions 324 extend in a radial direction from the center point Po32 toward the outer edge Fe32 and are in a strip shape with a predetermined width.

[0047] By means of this slot 323, the plate member 32 is divided into a central region 321 on the center point Po31 side with respect to the slot 323 and an outer edge region 322 on the outer edge Fe32 side with respect to the slot 323. The wall surface on the central region 321 side forming the slot 323 (through-hole) is the wall surface Fo21. The wall surface on the outer edge region 322 side is the wall surface Fi22. Hereinafter, the wall surface Fo21 is referred to as the inner wall surface Fo21 of the slot 323, and the wall surface Fi22 is referred to as the outer wall surface Fi22 of the slot 323.

[0048] The plate member 33 is made of metal and is a disc. The plate member 33 has an outer edge Fe33.

[0049] The plate member 31 corresponds to the first plate member. The plate member 32 corresponds to the second plate member. The plate member 33 corresponds to the third plate member.

[0050] The piezoelectric element 21, the piezoelectric element 22, the plate member 31, the plate member 32, and the plate member 33 are laminated as follows.

[0051] The plate member 31 is disposed on the surface F211 of the piezoelectric element 21 and is adhered by an adhesive or the like. More specifically, the plate member 31 is disposed on the piezoelectric element 21 in a state where the surface F312 faces the surface F211 adjacent thereto.

[0052] The plate member 33 is disposed on the surface F212 of the piezoelectric element 21 and is adhered by an adhesive or the like.

[0053] The piezoelectric element 22 is disposed on the surface opposite to the surface of the plate member 33 where the piezoelectric element 21 is disposed and is adhered by an adhesive or the like. At this time, the piezoelectric element 22 has the surface F222 facing the plate member 33 adjacent thereto.

[0054] The plate member 32 is disposed on the surface F221 of the piezoelectric element 22 and is adhered by an adhesive or the like. More specifically, the plate member 32 is disposed on the piezoelectric element 22 in a state where the surface F322 faces the surface F221 adjacent thereto.

[0055] In this case, when viewed from above (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). Also, when viewed from above (in the stacking direction), the slot 313 of plate member 31 and the slot 323 of plate member 32 overlap.

[0056] In this context, "overlapping" (or "matching") refers to allowing a range of manufacturing tolerances, including assembly errors.

[0057] The laminate 100 of the piezoelectric elements 21, 22, plate members 31, 32, and 33 is fixed and supported by supports ST1 and ST2.

[0058] Supports ST1 and ST2 are made of highly rigid materials such as metal.

[0059] The support ST1 is annular in shape and has an inner circumferential surface FiST1 and an outer circumferential surface FeST1. The circular diameter of the inner circumferential surface FiST1 when viewed from above is larger than the circular diameter of the outer wall surface Fi12 of the slot 313 when viewed from above.

[0060] The support ST2 is annular in shape and has an inner circumferential surface FiST2 and an outer circumferential surface FeST2. The circular diameter of the inner circumferential surface FiST2 when viewed from above is larger than the circular diameter of the outer wall surface Fi22 of the slot 323 when viewed from above.

[0061] The support ST1 is placed on the surface F311 of the plate member 31 and bonded with an adhesive or the like. In this case, the support ST1 is positioned such that, in a plan view, the circle formed by the inner circumferential surface FiST1 is on the outer edge side of the circle formed by the outer wall surface Fi12 of the slot 313. In other words, in a plan view, the inner circumferential surface FiST1 of the support ST1 and the outer wall surface Fi12 of the slot 313 are in different positions (they do not overlap). Furthermore, in a plan view, the inner circumferential surface FiST1 of the support ST1 is positioned further away from the center point Po of the actuator 10 than the outer wall surface Fi12 of the slot 313.

[0062] The support ST2 is placed on the surface F321 of the plate member 32 and bonded with an adhesive or the like. In this case, the support ST2 is positioned such that, in a plan view, the circle formed by the inner circumferential surface FiST2 is on the outer edge side of the circle formed by the outer wall surface Fi22 of the slot 323. In other words, in a plan view, the inner circumferential surface FiST2 of the support ST2 and the outer wall surface Fi22 of the slot 323 are in different positions (they do not overlap). Furthermore, in a plan view, the inner circumferential surface FiST2 of the support ST2 is positioned further away from the center point Po of the actuator 10 than the outer wall surface Fi22 of the slot 323.

[0063] With this configuration, the laminate 100 is supported and fixed by the support ST1 from one end in the stacking direction, and supported and fixed by the support ST2 from the other end in the stacking direction. More specifically, the support ST1 partially fixes the laminate 100 within a predetermined distance range in the direction from the outer edge of the laminate 100 toward the inside. The portion of the laminate 100 partially fixed by the support ST1 does not reach the outer wall surface Fi12 of the slot 313. This fixed portion corresponds to the first outer periphery.

[0064] The support ST2 fixes the laminate 100 within a predetermined distance range in the direction from the outer edge of the laminate 100 toward the inside. The portion of the laminate 100 partially fixed by the support ST2 does not reach the outer wall surface Fi22 of the slot 323. This fixed portion corresponds to the second outer periphery.

[0065] 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 substantially coincide with the resonant frequency of the actuator 10. The first and second drive signals are in opposite phase.

[0066] 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 the piezoelectric element 21 and the piezoelectric element 22 are opposite. Furthermore, the expansion and contraction directions of the piezoelectric element 21 and the piezoelectric element 22 are opposite on the central side and the outer edge side of the polarization reversal position Ppr.

[0067] The stress due to the expansion and contraction strain of the piezoelectric elements 21 and 22 is applied to the plate members 31, 32, and 33. Here, the laminate 100 is fixed at the first outer periphery and the second outer periphery. Therefore, the laminate 100 experiences bending vibration due to the stress due to the expansion and contraction strain of the piezoelectric elements 21 and 22. Bending vibration is a vibration in which the portion of the laminate 100 closer to the center point Po displaces in a direction parallel to the lamination direction, while the outer edge portions (first outer periphery and second outer periphery) of the laminate 100 are fixed. The point of maximum displacement of this bending vibration approximately coincides with the center point Po.

[0068] 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.

[0069] 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.

[0070] Furthermore, the actuator 10 employs a so-called bimorph configuration by incorporating piezoelectric elements 21 and 22. This allows for a larger vibration amplitude during bending. In addition, the actuator 10 employs polarization reversal. This improves vibration efficiency.

[0071] Furthermore, the actuator 10 is provided with a slot 313 in the plate member 31. Also, the actuator 10 is provided with a slot 323 in the plate member 32. The slot 313 is located on the side of the center point Po closer to the inner surface of the first outer periphery (the inner surface FiST1 of the support ST1). The slot 323 is located on the side of the center point Po closer to the inner surface of the second outer periphery (the inner surface FiST2 of the support ST2).

[0072] Figure 5(A) schematically shows the difference in amplitude between the present configuration and the comparative configuration, and Figure 5(B) is a simplified diagram showing the relationship between the slot and polarization reversal position in relation to Figure 5(A). In Figure 5(A), the solid line shows the vibration of the present configuration, and the dashed line shows the vibration of the comparative configuration. The comparative configuration is a configuration without a slot.

[0073] In the areas where slots 313 and 323 are formed, the thickness of the laminate 100 is only the thickness of the piezoelectric element 21, the plate member 33, and the piezoelectric element 22, making it thinner than the areas where slots 313 and 323 are not formed. Therefore, the areas of the laminate 100 where slots 313 and 323 are formed have lower rigidity and higher flexibility than the areas where slots 313 and 323 are not formed.

[0074] Therefore, in the areas where slots 313 and 323 are formed, the strain of the piezoelectric elements 21 and 22 is suppressed from being constrained by the plate members 31 and 32. As a result, as shown in Figure 5(A), the amount of vibration (amplitude) of the laminate 100 at the formation positions of slots 313 and 323 can be increased.

[0075] Furthermore, the slots 313 and 323 are formed near the outer edges (first outer periphery and second outer periphery) where the laminate 100 is fixed. Therefore, the actuator 10 can increase the amount of vibration from near the fixed outer edges. This allows the amount of vibration at the center point Po of the actuator 10 to be increased.

[0076] Furthermore, slots 313 and 323 are located at positions different from the polarization reversal position Ppr of the piezoelectric elements 21 and 22, and are located outside the polarization reversal position Ppr. At the polarization reversal position Ppr, the strain of the piezoelectric elements 21 and 22 is small, so their contribution to vibration is small.

[0077] Therefore, by positioning slots 313 and 323 on the outer edge side of the polarization reversal position Ppr, the flexibility of the laminate 100 can be increased in areas with significant strain, unlike the polarization reversal position Ppr where almost no strain occurs. As a result, the actuator 10 can increase the amount of vibration and generate vibrations more efficiently.

[0078] Furthermore, slots 313 and 323 are not present at the positions where the laminate 100 is fixed by supports ST1 and ST2. Therefore, the actuator 10 can suppress a decrease in rigidity at the fixed end of the vibration. This improves the reliability of the actuator 10.

[0079] Furthermore, the formation position of the slot 313 preferably satisfies the following conditions. As shown in Figure 4(B), the midpoint Psl of the slot 313 is defined as the midpoint of a line perpendicular to both the inner wall surface Fo11 and the outer wall surface Fi12. The distance Lsl between the center point (center point Po) of the slot 313 and the inner wall surface Fo11 or inner wall surface Fo21 is between 1 / 4 and 7 / 8 of the distance LsST between the center point (center point Po) of the slot 313 and the inner circumferential surface FiST1 of the support ST1.

[0080] As a result, the actuator 10 can generate vibrations more efficiently and produce larger vibrations.

[0081] [Second Embodiment] An actuator according to a second embodiment of the present invention will be described with reference to the figures. Figure 6 is an exploded perspective view of the actuator according to the second embodiment.

[0082] In the actuator 10A according to the second embodiment, the relationship between the orientations of the piezoelectric elements 21 and 22, and the relationship between the orientations of the plate members 31 and 32 are different from those of the actuator 10 according to the first embodiment. The other components of the actuator 10A are the same as those of the actuator 10, and the description of the similar parts will be omitted.

[0083] The actuator 10A includes a laminate 100A. The laminate 100A, like the laminate 100, is composed of piezoelectric elements 21, 22, plate members 31, 32, and 33.

[0084] The electrode-free portions of the annular sections of the driving electrodes 211 and 212 in piezoelectric element 21 and the electrode-free portions of the annular sections of the driving electrodes 221 and 222 in piezoelectric element 22 are offset by 90° in a plan view (viewed in the stacking direction). Note that this 90° includes manufacturing tolerances, etc., and may be in the range of, for example, 90° ± 5°.

[0085] The multiple beam portions 314 in plate member 31 and the multiple beam portions 324 in plate member 32 are offset by 90° in a plan view (viewed in the stacking direction). Note that this 90° includes manufacturing tolerances, etc., and may be in the range of, for example, 90° ± 5°.

[0086] The non-electrode-formed portions of the annular sections of the driving electrodes 211 and 212 and the multiple beam sections 314 overlap in a plan view (viewed in the stacking direction).

[0087] The non-electrode-formed portions of the annular sections of the driving electrodes 221 and 222 and the multiple beam sections 324 overlap in a plan view (viewed in the stacking direction).

[0088] With this configuration, actuator 10A can achieve the same effects as actuator 10. Furthermore, in actuator 10A, either the slot 313 of plate member 31 or the slot 323 of plate member 32 is arranged throughout the entire circumferential region of the annular shape. As a result, actuator 10A can suppress differences in vibration due to position in the circumferential direction.

[0089] [Third Embodiment] An actuator according to a third embodiment of the present invention will be described with reference to the figures. Figure 7 is an exploded perspective view of the actuator according to the third embodiment.

[0090] The actuator 10B according to the third embodiment differs from the actuator 10 according to the first embodiment in that it has a unimorph structure. 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.

[0091] The actuator 10B comprises a laminate 100B. The laminate 100B comprises a piezoelectric element 21, a plate member 31, and a plate member 33.

[0092] The support ST2 is connected to the plate member 33 and bonded to it with an adhesive or the like.

[0093] With this configuration, actuator 10B can achieve the same effects as actuator 10. Furthermore, since actuator 10B has a unimorph structure, it can have fewer components than actuator 10, which has a bimorph structure, thus enabling a thinner design.

[0094] [Fourth Embodiment] An actuator according to a fourth embodiment of the present invention will be described with reference to the figures. Figure 8 is an exploded perspective view of the actuator according to the fourth embodiment.

[0095] The actuator 10C according to the fourth embodiment differs from the actuator 10A according to the second embodiment in that it includes piezoelectric elements 21C and 22C. The other components of the actuator 10C are the same as those of the actuator 10A, and a description of the similar parts will be omitted.

[0096] The actuator 10C comprises a laminate 100C. The laminate 100C comprises a piezoelectric element 21C and a piezoelectric element 22C.

[0097] Piezoelectric elements 21C and 22C have not undergone polarization reversal treatment.

[0098] With this configuration, actuator 10C can achieve the same effects as actuator 10.

[0099] [Variations of Slots] Figures 9(A) and 9(B) are plan views showing variations of slots, respectively. Figures 10(A), 10(B), 10(C), and 10(D) are cross-sectional views showing variations of slots. In the following, variations of slots for plate member 31 are shown as an example, but similar variations can be constructed for slots for plate member 32.

[0100] The slot 313 of the plate member 31X1 shown in Figure 9(A) is composed of three partial slots. The three partial slots have a central angle of approximately 120° and are arranged at equal intervals in the circumferential direction of the slot 313. The three partial slots are arranged point-symmetrically with respect to the center point Po 31.

[0101] Furthermore, the number of sub-slots that make up a slot is not limited to two or three.

[0102] The slot 313 of the plate member 31X2 shown in Figure 9(B) is annular in shape. In this configuration, the plate member 31X2 can also provide power by connecting a power supply wiring conductor to the central region 311 of the plate member 31X2. In this case, it is also possible to supply drive signals with opposite phases to the central and annular portions of the drive electrode through the central region 311 and the outer edge region 312 of the plate member 31X2, respectively, without performing polarization reversal processing of the piezoelectric element.

[0103] The plate member 31Y1 shown in Figure 10(A) is provided with a slot 313Y1. The opening area of ​​the slot 313Y1 on the surface F311 side is larger than the opening area on the surface F312 side.

[0104] The plate member 31Y2 shown in Figure 10(B) is provided with a slot 313Y2. The opening area of ​​the slot 313Y1 on the side of surface F312 is larger than the opening area on the side of surface F311.

[0105] The plate member 31Y3 shown in Figure 10(C) is provided with a slot 313Y3. The slot 313Y3 is a recess that is recessed from the surface F311 and does not reach the surface F312.

[0106] The plate member 31Y4 shown in Figure 10(D) is provided with a slot 313Y4. The slot 313Y4 is a recess that is recessed from the surface F312 and does not reach the surface F311.

[0107] As shown above, the slot may be a through-hole or a non-through recess.

[0108] In the embodiments described above, the outer edges of the piezoelectric element, plate member, and support were shown to coincide in a plan view. However, the outer edges of the piezoelectric element, plate member, and support do not necessarily have to coincide in a plan view. Furthermore, the outer shapes of the plate member and support are not limited to circular shapes.

[0109] <1> An actuator comprising: a first piezoelectric element having a first surface and a second surface facing each other; a first plate member having a third surface and a fourth surface facing each other, the fourth surface being positioned with respect to the first surface; and a ring-shaped first support, wherein the first plate member is fixed to the first support within a predetermined distance range in the direction from the outer edges of the third and fourth surfaces toward the inside, the inner circumferential surface of the first support is circular, the first plate member has a first slot, the first slot is positioned closer to the center of the first plate member than the portion fixed to the first support, and is composed of a recess that is recessed from the third surface or the fourth surface, or a through portion that penetrates between the third surface and the fourth surface.

[0110] <2> The actuator according to <1>, wherein the first slot is composed of a plurality of arc-shaped partial slots, and the plurality of partial slots are arranged symmetrically with respect to a circular center point formed by the inner circumferential surface of the first support.

[0111] <3> The actuator according to <2>, wherein the plurality of partial slots are the same shape and are arranged at equal intervals in the circumferential direction of the circle.

[0112] <4> The actuator described in <1>, wherein the first slot is annular in shape.

[0113] <5> The actuator according to any one of <1> to <4>, wherein the distance between the center point of the circle formed by the inner circumferential surface of the first support and the inner wall surface forming the first slot is 1 / 4 or more and 7 / 8 or less of the distance between the center point and the inner circumferential surface of the first support.

[0114] <6> The actuator according to any one of <1> to <5>, wherein the first piezoelectric element is polarized at a position midway from the center of the first piezoelectric element in a plan view toward the outer edge, and the first slot is located toward the outer edge than the position of polarization reversal in a plan view.

[0115] <7> The actuator according to any one of <1> to <6>, comprising: a second piezoelectric element having a fifth and a sixth surface facing each other; a second plate member having a seventh and an eighth surface facing each other, with the eighth surface positioned on the fifth surface; a third plate member positioned between the second surface of the first piezoelectric element and the sixth surface of the second piezoelectric element; and a ring-shaped second support, wherein the second plate member is fixed to the second support within a predetermined distance range in the direction toward the inside from the outer edges of the seventh and eighth surfaces, the inner circumferential surface of the second support is circular, and the second plate member comprises a second slot, the second slot being positioned closer to the center of the second plate member than the portion fixed to the second support, and consisting of a recess recessing from the seventh surface or a through-hole penetrating between the seventh surface and the eighth surface.

[0116] 10, 10A, 10B, 10C: Actuator 21, 21C, 22, 22C: Piezoelectric element 31, 31X1, 31X2, 31Y1, 31Y2, 31Y3, 31Y4, 32, 33: Plate member 100, 100A, 100B, 100C: Laminate 210, 220: Piezoelectric material 211, 222: Driving electrode 311, 321: Central region 312, 322: Outer edge region 313, 313Y1, 313Y2, 313Y3, 313Y4, 323: Slot 314, 324: Beam F211, F212, F221, F222, F311, F312, F321, F322: Surface Fe21, Fe22, Fe31, Fe32, Fe33: Outer edge FeST1, FeST2: Outer circumferential surface Fi12, Fi22: Outer wall surface FiST1, FiST2: Inner circumferential surface Fo11, Fo21: Inner wall surface LsST, Lsl: Distance Po, Po21, Po22, Po31, Po32, Po33: Center point Ppr: Polarization inversion position Psl: Midpoint ST1, ST2: Support

Claims

1. An actuator comprising: a first piezoelectric element having a first surface and a second surface facing each other; a first plate member having a third surface and a fourth surface facing each other, with the fourth surface positioned on the first surface; and a ring-shaped first support, wherein the first plate member is fixed to the first support within a predetermined distance range in the direction from the outer edges of the third and fourth surfaces toward the inside, the inner circumferential surface of the first support is circular, and the first plate member has a first slot, the first slot being positioned closer to the center of the first plate member than the portion fixed to the first support, and consisting of a recess recessing from the third surface or the fourth surface, or a through-hole penetrating between the third surface and the fourth surface.

2. The actuator according to claim 1, wherein the first slot is composed of a plurality of arc-shaped partial slots, and the plurality of partial slots are arranged symmetrically with respect to a circular center point formed by the inner circumferential surface of the first support.

3. The actuator according to claim 2, wherein the plurality of partial slots are the same shape and are arranged at equal intervals in the circumferential direction of the circle.

4. The actuator according to claim 1, wherein the first slot is annular in shape.

5. The actuator according to any one of claims 1 to 4, wherein the distance between the circular center point formed by the inner circumferential surface of the first support and the inner wall surface forming the first slot is 1 / 4 or more and 7 / 8 or less of the distance between the center point and the inner circumferential surface of the first support.

6. The actuator according to any one of claims 1 to 5, wherein the first piezoelectric element is polarized at a position midway from the center of the first piezoelectric element to the outer edge in a plan view, and the first slot is located on the outer edge side of the polarization reversal position in a plan view.

7. An actuator according to any one of claims 1 to 6, comprising: a second piezoelectric element having a fifth and a sixth surface facing each other; a second plate member having a seventh and an eighth surface facing each other, with the eighth surface positioned on the fifth surface; a third plate member positioned between the second surface of the first piezoelectric element and the sixth surface of the second piezoelectric element; and a ring-shaped second support, wherein the second plate member is fixed to the second support within a predetermined distance range in the direction from the outer edges of the seventh and eighth surfaces toward the inside; the inner circumferential surface of the second support is circular; the second plate member comprises a second slot, the second slot being positioned closer to the center of the second plate member than the portion fixed to the second support, and consisting of a recess recessing from the seventh surface or a through-hole penetrating between the seventh surface and the eighth surface.

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