Actuator

Abstract

An actuator according to the present invention comprises: a piezoelectric body having a first main surface and a second main surface; a first electrode disposed on the first main surface; a second electrode disposed on the second main surface; a first vibrating plate disposed on the first electrode; and a second vibrating plate disposed on the second electrode. The thickness of the first vibrating plate and the thickness of the second vibrating plate are different, and fillets are formed between the peripheral edge of the piezoelectric body and the first vibrating plate and between the peripheral edge of the piezoelectric body and the second vibrating plate, respectively.

Description

Actuator

[0001] The present invention relates to an actuator having a diaphragm.

[0002] Patent Document 1 discloses an actuator in which a plate-shaped piezoelectric element is attached to a plate-shaped vibration plate. The actuator vibrates in a bending manner from the center to the periphery in response to a driving voltage. The peripheral portion of the actuator is substantially unconstrained.

[0003] Patent Document 2 discloses a configuration in which a first vibration plate and a second vibration plate are attached to a first main surface and a second main surface of a piezoelectric body, respectively.

[0004] International Publication No. 2003-50712

[0005] In the structure of Patent Document 1, if the amplitude of the actuator is increased to increase the output, the piezoelectric element may crack and break down.

[0006] The structure of Patent Document 2 can prevent the piezoelectric element from cracking, but if this configuration is applied to the structure of Patent Document 1, there is a possibility that the peripheral portions of the unconstrained first and second vibration plates will come into contact and cause a short circuit.

[0007] Therefore, an object of the present invention is to provide an actuator that prevents the piezoelectric body from cracking and prevents the peripheral portions of the unconstrained first and second vibration plates from coming into contact and causing a short circuit.

[0008] An actuator according to one embodiment of the present invention includes a piezoelectric body having a first main surface and a second main surface, a first electrode disposed on the first main surface, a second electrode disposed on the second main surface, a first diaphragm disposed on the first electrode, and a second diaphragm disposed on the second electrode. The first diaphragm and the second diaphragm have different thicknesses, and fillets are formed between the periphery of the piezoelectric body and the first diaphragm, and between the periphery of the piezoelectric body and the second diaphragm.

[0009] An actuator according to another embodiment of the present invention includes a first piezoelectric element having a first main surface and a second main surface, a first electrode disposed on the first main surface, a second electrode disposed on the second main surface, a second piezoelectric element having a third main surface and a fourth main surface, a third electrode disposed on the third main surface, a fourth electrode disposed on the fourth main surface, a first diaphragm disposed on the first electrode, a second diaphragm disposed on the second electrode and the third electrode, and a third diaphragm disposed on the fourth electrode. Fillets are formed between a periphery of the first piezoelectric element and the first diaphragm, between a periphery of the first piezoelectric element and the second diaphragm, between a periphery of the second piezoelectric element and the second diaphragm, and between a periphery of the second piezoelectric element and the third diaphragm.

[0010] The actuator has vibration plates on both main surfaces of the piezoelectric body, which prevents the piezoelectric body from cracking and breaking. Furthermore, the fillet formed between the periphery of the piezoelectric body and the vibration plate prevents the peripheral portions of the two vibration plates from bending toward each other, preventing the peripheral portions of the two unconstrained vibration plates from coming into contact and shorting out.

[0011] According to this invention, it is possible to prevent the piezoelectric body from cracking, and also to prevent the peripheral portions of the unconstrained first and second diaphragms from coming into contact with each other and causing a short circuit.

[0012] 1. A cross-sectional view of actuator 1. A plan view of first vibration plate 11. A plan view of piezoelectric body 10. A cross-sectional view of actuator 1 during bending vibration. A cross-sectional view of an actuator according to a reference example during bending vibration. A cross-sectional view of actuator 2. A cross-sectional view of actuator 2 during bending vibration. A diagram showing the relationship between the distance from the neutral plane of a main surface (the main surface away from the neutral plane) of a piezoelectric body and stress / amplitude (stress per amplitude). A diagram showing the relationship between the distance from the neutral plane of a main surface of a piezoelectric body and amplitude. A diagram showing the relationship between amplitude and radial stress at the center of a piezoelectric body. A cross-sectional view showing the structure of bimorph variation 1. A cross-sectional view showing the structure of bimorph variation 2. A plan view showing the structure of bimorph variation 3. A cross-sectional view showing the structure of bimorph variation 3. An exploded perspective view showing the structure of bimorph variation 4. An exploded perspective view of actuator 2E according to variation 5. A cross-sectional view showing the first vibration plate 11 and the following portion of actuator 2E. A cross-sectional view showing the first vibration plate 11 and the following portion of actuator 2E. FIG. 19 is a cross-sectional view showing the structure of bimorph variation 6. FIG. 20 is a partially enlarged view of FIG. 19. Fig. 21(A) is a plan view of electrode patterns D122A and D122B formed on the insulator layer LY121, and Fig. 21(B) is a plan view of D123A and D123B formed on the insulator layer LY122. Fig. 22 is a plan view of electrode patterns, via electrodes, and through holes formed between the insulator layer LY121 and the insulator layer LY122. Fig. 23(A) is a plan view of the insulator layer LY121, and Fig. 23(B) is a plan view of the insulator layer LY122.

[0013] An actuator according to a first embodiment of the present invention will be described with reference to the drawings. In the drawings showing the following embodiments, the shapes of the respective components are partially or entirely exaggerated to make the description easier to understand.

[0014] 1 is a cross-sectional view of an actuator 1 according to a first embodiment of the present invention. The actuator 1 includes a piezoelectric body 10, a first diaphragm 11, a second diaphragm 12, a fillet 13, a first electrode 14, and a second electrode 15.

[0015] Fig. 2 is a plan view of the first diaphragm 11, and Fig. 3 is a plan view of the piezoelectric body 10. The cross-sectional view of Fig. 1 is a cross-sectional view taken along line AA shown in Figs.

[0016] The piezoelectric body 10 is made of, for example, lead zirconate titanate ceramics. The piezoelectric body 10 has a thin, disk-like shape. A first electrode 14 is formed on a first main surface of the piezoelectric body 10 by, for example, sputtering, and a second electrode 15 is formed on a second main surface by, for example, sputtering. The piezoelectric body 10 is distorted by a driving voltage applied to the first electrode 14 and the second electrode 15. In this embodiment, the outer diameter of the piezoelectric body 10 is larger than the outer diameters of the first electrode 14 and the second electrode 15 in a plan view.

[0017] The first diaphragm 11 is attached to the first electrode 14 with an adhesive. The second diaphragm 12 is attached to the second electrode 15 with an adhesive. The adhesive contains a plurality of conductive fillers. The plurality of conductive fillers establish electrical continuity between the electrode and the diaphragm when the thickness of the adhesive is below a predetermined value. However, insulating resin is present between the fillers, making the adhesive non-conductive. Therefore, the adhesive is conductive in the thickness direction when the thickness is below a predetermined thickness, and insulating when the thickness exceeds the predetermined thickness. For example, the adhesive in the portion sandwiched between the first electrode 14 and the first diaphragm 11 and the adhesive in the portion sandwiched between the second electrode 15 and the second diaphragm 12 are conductive when their thicknesses are below a predetermined thickness.

[0018] The first diaphragm 11 and the second diaphragm 12 are disk-shaped. In this embodiment, the first diaphragm 11 and the second diaphragm 12 have the same shape in a plan view. In this embodiment, the outer diameter of the piezoelectric body 10 is smaller than the outer diameters of the first diaphragm 11 and the second diaphragm 12 in a plan view.

[0019] The thickness of the first diaphragm 11 and the thickness of the second diaphragm 12 are different. In this embodiment, the first diaphragm 11 is thicker than the second diaphragm 12. However, the first diaphragm 11 may be thinner than the second diaphragm 12. Therefore, the second diaphragm 12 is more easily deformed and bent than the first diaphragm 11.

[0020] The first diaphragm 11 and the second diaphragm 12 are made of a conductive material. Conductor wires (not shown) are connected to the first diaphragm 11 and the second diaphragm 12. A drive circuit is electrically connected to the conductor wires and the first diaphragm 11 and the second diaphragm 12. This allows a drive voltage to be applied to the first diaphragm 11 and the second diaphragm 12. The first diaphragm 11 and the second diaphragm 12 are attached to the first electrode 14 and the second electrode 15, respectively, with the adhesive. Therefore, the drive voltage is applied to the first electrode 14 and the second electrode 15.

[0021] The actuator 1 is designed to vibrate at a predetermined resonance frequency. A drive voltage having a frequency that matches the resonance frequency is applied to the first electrode 14 and the second electrode 15. This causes the actuator 1 to vibrate in a rotationally symmetrical (concentric) bending pattern from the center to the periphery.

[0022] 4 is a cross-sectional view of the actuator 1 during bending vibration. The arrows in the figure indicate the deformation direction of the piezoelectric body 10. In FIG. 4, an example is shown in which the piezoelectric body 10 contracts in a direction parallel to the main surface.

[0023] When a drive voltage that causes the piezoelectric body 10 to contract in a direction parallel to the main surface is applied to the first diaphragm 11 or the second diaphragm 12, the actuator 1 deforms in a manner as shown in Fig. 4. As shown in Fig. 4, when the piezoelectric body 10 expands in a direction parallel to the main surface, the first diaphragm 11 is thicker than the second diaphragm 12, and therefore the centers of the piezoelectric body 10, the first diaphragm 11, and the second diaphragm 12 bend and deform in a convex shape along the normal direction. Furthermore, if the piezoelectric body 10 contracts in a direction parallel to the main surface, the centers of the piezoelectric body 10, the first diaphragm 11, and the second diaphragm 12 bend and deform in a concave shape along the normal direction.

[0024] Therefore, the actuator 1 of this embodiment functions as a piezoelectric unimorph vibrator. Such an actuator 1 functions as a piezoelectric pump when it is housed in a pump chamber having an air vent, for example.

[0025] The actuator 1 of this embodiment is not constrained at its periphery, and is therefore capable of achieving a large amplitude despite its small, low-profile structure. Furthermore, a first diaphragm 11 and a second diaphragm 12 are disposed on both main surfaces (first and second main surfaces) of the piezoelectric body 10 of the actuator 1 of this embodiment. Therefore, even if the amplitude of the actuator is increased to increase output, there is no risk of the piezoelectric body 10 cracking. In particular, in a plan view of the actuator 1, the outer diameter of the piezoelectric body 10 is smaller than the outer diameters of the first diaphragm 11 and the second diaphragm 12. Therefore, the side surfaces of the piezoelectric body 10 are not directly touched when dropped or transported, further reducing damage.

[0026] Furthermore, in the actuator 1 of this embodiment, fillets 13 are formed between the piezoelectric body 10 and the first diaphragm 11, and between the periphery of the piezoelectric body 10 and the second diaphragm 12. The fillets 13 are formed by the overflow of the adhesive described above. The adhesive that forms the fillets 13 exceeds a predetermined thickness and has insulating properties. In the actuator 1 of this embodiment, even in a state where the periphery is not restrained by a rigid body other than the fillets 13, the presence of the fillets 13 between the first diaphragm 11 and the second diaphragm 12 makes it possible to prevent the peripheries of the first diaphragm 11 and the second diaphragm 12 from coming into contact and causing a short circuit, due to the presence of the fillets 13 between them.

[0027] 5 is a cross-sectional view of an actuator according to a reference example during bending vibration. As shown in Fig. 5, in an actuator without fillets 13, when the center of diaphragm 90 is bent and deformed in a convex shape along the normal direction, the peripheral portion of diaphragm 90 is bent toward the opposing other diaphragm 91 because the peripheral portion is not constrained. Therefore, there is a possibility that diaphragm 90 and diaphragm 91 may come into contact and cause a short circuit.

[0028] In contrast, the actuator 1 of this embodiment has fillets 13 interposed between the first diaphragm 11 and the second diaphragm 12, which prevents the peripheral portion of the second diaphragm 12 from bending toward the opposing first diaphragm 11 due to the peripheral portion not being constrained. Furthermore, by interposing fillets 13 between the first diaphragm 11 and the second diaphragm 12, it is possible to prevent the peripheral portions of the first diaphragm 11 and the second diaphragm 12 from coming into direct contact with each other and causing a short circuit.

[0029] In the actuator 1 of this embodiment, the area of ​​the piezoelectric body 10 is larger than the areas of the first electrode 14 and the second electrode 15 in a plan view. This configuration is not essential to the present invention, but this configuration prevents the electrodes (first electrode 14 and second electrode 15) from protruding onto the side surfaces of the piezoelectric body 10. Therefore, when the electrodes are formed, the electrodes do not wrap around the side surfaces of the piezoelectric body 10, and short circuits can be suppressed.

[0030] Next, Fig. 6 is a cross-sectional view of an actuator 2 according to a second embodiment. The same components as those in the actuator 1 shown in Fig. 1 are denoted by the same reference numerals, and a description thereof will be omitted. The actuator 2 includes a first piezoelectric element 10A, a first diaphragm 11, a second diaphragm 12, a fillet 13, a first electrode 14, a second electrode 15, a second piezoelectric element 10B, a third diaphragm 101, a third electrode 151, and a fourth electrode 152.

[0031] The first piezoelectric body 10A has the same configuration and function as the piezoelectric body 10 of the first embodiment. The second piezoelectric body 10B has the same structure as the first piezoelectric body 10A. The second piezoelectric body 10B has a third main surface and a fourth main surface. A third electrode 151 is formed on the third main surface of the second piezoelectric body 10B by, for example, sputtering, and a fourth electrode 152 is formed on the fourth main surface by, for example, sputtering.

[0032] The second diaphragm 12 is attached to the third electrode 151 with an adhesive. The third diaphragm 101 is attached to the fourth electrode 152 with an adhesive. Therefore, in the actuator 2 of this embodiment, fillets 13 are formed between the periphery of the first piezoelectric body 10A and the first diaphragm 11, between the periphery of the first piezoelectric body 10A and the second diaphragm 12, between the periphery of the second piezoelectric body 10B and the second diaphragm 12, and between the periphery of the second piezoelectric body 10B and the third diaphragm 101.

[0033] The third diaphragm 101 has a disk shape. In this embodiment, the first diaphragm 11 and the third diaphragm 101 have the same shape in a plan view and the same outer diameter.

[0034] In this embodiment, the outer diameters of the first piezoelectric body 10A and the second piezoelectric body 10B are smaller than the outer diameters of the first vibration plate 11 and the third vibration plate 101 in plan view.

[0035] In this embodiment, the first diaphragm 11, the second diaphragm 12, and the third diaphragm 101 all have the same shape and outer diameter. The thickness of the first diaphragm 11, the thickness of the second diaphragm 12, and the thickness of the third diaphragm 101 are also the same. However, the second diaphragm 12 may be thinner or thicker than the first diaphragm 11 and the third diaphragm 101.

[0036] A drive voltage is applied to the first diaphragm 11, the second diaphragm 12, and the third diaphragm 101. A drive voltage having a frequency that matches the resonant frequency of the actuator 2 is applied to the first diaphragm 11, the second diaphragm 12, and the third diaphragm 101. The drive voltage is applied to the first electrode 14, the second electrode 15, the third electrode 151, and the fourth electrode 152. The second electrode 15 and the third electrode 151 are attached to the second diaphragm 12 and therefore have the same potential. Drive voltages of opposite polarities are applied to the first electrode 14 and the fourth electrode 152 with respect to the potential of the second diaphragm.

[0037] FIG. 7 is a cross-sectional view of the actuator 2 during bending vibration. In the example of FIG. 7, the first piezoelectric element 10A expands in a direction parallel to the main surface, and the second piezoelectric element 10B contracts in a direction parallel to the main surface. In this case, the centers of the first vibration plate 11, the second piezoelectric element 10B, the second vibration plate 12, the first piezoelectric element 10A, and the third vibration plate 101 are bent and deformed in a convex shape along the normal direction. Although not shown, when the first piezoelectric element 10A contracts in a direction parallel to the main surface, the second piezoelectric element 10B expands in a direction parallel to the main surface. In this case, the centers of the first vibration plate 11, the second piezoelectric element 10B, the second vibration plate 12, the first piezoelectric element 10A, and the third vibration plate 101 are bent and deformed in a concave shape along the normal direction. The vertical center position of the second vibration plate 12 forms a neutral plane where the stress in a direction parallel to the main surface is approximately zero.

[0038] Therefore, the actuator 2 of this embodiment functions as a piezoelectric bimorph vibrator. This type of actuator 2 also functions as a piezoelectric pump when it is housed in a pump chamber having an air vent, for example.

[0039] The actuator 2 also has no peripheral constraints, allowing it to achieve a large amplitude despite its small, low-profile structure. Furthermore, vibration plates are disposed on both main surfaces of the first piezoelectric element 10A and the second piezoelectric element 10B of the actuator 2. Therefore, even if the amplitude of the actuator is increased to increase output, there is no risk of the piezoelectric elements cracking. In particular, in a plan view of the actuator 2, the outer diameters of the first piezoelectric element 10A and the second piezoelectric element 10B are smaller than the outer diameters of the first vibration plate 11 and the third vibration plate 101 on the outside of the actuator 2. Therefore, the side surfaces of the first piezoelectric element 10A and the second piezoelectric element 10B do not come into direct contact with each other when the actuator is dropped or transported, further reducing the risk of breakage.

[0040] Furthermore, in the actuator 2 of this embodiment, fillets 13 are formed between the periphery of the first piezoelectric body 10A and the first diaphragm 11, between the periphery of the first piezoelectric body 10A and the second diaphragm 12, between the periphery of the second piezoelectric body 10B and the second diaphragm 12, and between the periphery of the second piezoelectric body 10B and the third diaphragm 101. The fillets 13 are formed by the overflow of the adhesive described above. The actuator 2 of this embodiment can prevent the peripheries of the first diaphragm 11 and the second diaphragm 12 from contacting each other even when their peripheral portions are not constrained. Furthermore, the actuator 2 of this embodiment can prevent the peripheries of the second diaphragm 12 and the third diaphragm 101 from contacting each other even when their peripheral portions are not constrained. Furthermore, the actuator 2 of this embodiment can prevent the peripheries of the first diaphragm 11 and the third diaphragm 101 from contacting each other even when their peripheral portions are not constrained.

[0041] Furthermore, compared to the actuator 1, which is a piezoelectric unimorph vibrator, the actuator 2 can efficiently convert the same driving voltage into bending vibration, and can increase the amplitude per voltage.

[0042] FIG. 8 is a diagram showing the relationship between the distance from the neutral plane of the main surface (the main surface away from the neutral plane) of a piezoelectric body and stress / amplitude (stress per amplitude), and FIG. 9 is a diagram showing the relationship between the distance from the neutral plane of the main surface of the piezoelectric body and amplitude. FIG. 10 is a diagram showing the relationship between amplitude and radial stress at the center of the piezoelectric body. The thickness of the diaphragm is adjusted so that the resonant frequencies are equal in all cases. The stress shown in FIG. 8 is the stress generated in the planar direction from the main surface of the piezoelectric body at the center position when viewed in a plane. The stress shown in FIG. 10 is the stress generated in the radial direction (planar direction) from the main surface of the piezoelectric body at the center position when viewed in a plane. The unimorph shown in FIGS. 8, 9, and 10 corresponds to the structure of actuator 1, and the bimorph corresponds to the structure of actuator 2.

[0043] As shown in Figure 8, for both unimorphs and bimorphs, the stress per amplitude increases as the distance from the neutral plane of the piezoelectric body's main surface increases. Furthermore, for the same distance from the neutral plane of the piezoelectric body's main surface, the stress generated in the piezoelectric body is slightly greater in the unimorph. On the other hand, as shown in Figure 9, for the same distance from the neutral plane of the piezoelectric body's main surface, the bimorph has a much greater amplitude as an actuator. Furthermore, as shown in Figure 10, for the same value of radial stress at the center of the piezoelectric body, the bimorph has a much greater amplitude as an actuator.

[0044] As shown in the cross-sectional views of Figures 4 and 7, in a unimorph, vibration plates are attached to both main surfaces of the piezoelectric body, inhibiting bending vibration and increasing the expansion / contraction vibration component, whereas in a bimorph, even if vibration plates are attached to both main surfaces of the piezoelectric body, the paired piezoelectric bodies expand and contract in opposite directions, efficiently converting the vibration into bending vibration. Therefore, in a bimorph, the vibration plate on the outermost layer of the actuator can be made thicker to adjust the resonance frequency, and the neutral plane and the main surfaces of the piezoelectric body are closer than in a unimorph, so the stress per amplitude related to the piezoelectric body is reduced. In other words, even with the same stress, the amplitude as an actuator is much greater in a bimorph.

[0045] Therefore, in a bimorph such as actuator 2, the piezoelectric body is less likely to break when the output is increased and the amplitude is made larger than in a unimorph such as actuator 1.

[0046] Next, Fig. 11 is a cross-sectional view showing the structure of bimorph Variation 1. In actuator 2A according to Variation 1 of Fig. 11, the outer diameters of first piezoelectric body 10A and second piezoelectric body 10B in plan view are larger than the outer diameter of second diaphragm 12. As a result, first piezoelectric body 10A is present between the end of first diaphragm 11 and the end of second diaphragm 12, and second piezoelectric body 10B is present between the end of third diaphragm 101 and the end of second diaphragm 12. This further reduces the possibility of contact between first diaphragm 11 and second diaphragm 12 and between third diaphragm 101 and second diaphragm 12 during vibration, thereby further suppressing the possibility of short-circuiting.

[0047] Fig. 12 is a cross-sectional view showing the structure of bimorph variation 2. In actuator 2B according to variation 2 of Fig. 12, first piezoelectric body 10A, second piezoelectric body 10B, first diaphragm 11, second diaphragm 12, and third diaphragm 101 all have the same outer diameter in plan view.

[0048] In actuator 2B as well, fillets 13 are formed between the periphery of first piezoelectric body 10A and first diaphragm 11, between the periphery of first piezoelectric body 10A and second diaphragm 12, between the periphery of second piezoelectric body 10B and second diaphragm 12, and between the periphery of second piezoelectric body 10B and third diaphragm 101. In actuator 2B as well, diaphragms are disposed on both main surfaces of first piezoelectric body 10A and second piezoelectric body 10B. Therefore, even if the amplitude of the actuator is increased to increase output, there is no risk of the piezoelectric body cracking.

[0049] Next, FIG. 13 is a plan view showing the structure of a bimorph variation 3, and FIG. 14 is a cross-sectional view. The first diaphragm 11, the second diaphragm 12, and the third diaphragm 101 according to variation 3 all have the same shape, thickness, and outer diameter. The first frame 123, the second frame 133, and the third frame 143 are annular and surround the first diaphragm 11, the second diaphragm 12, and the third diaphragm 101, respectively. The upper main surface of the first frame 123 and the lower main surface of the second frame 133 are connected via a spacer 160. The spacer 160 has the same inner and outer diameters as the first frame 123 and the second frame 133. The thickness of the spacer 160 is approximately the same as the thickness of the first piezoelectric element 10A. The first diaphragm 11 and the second diaphragm 12 face each other via the spacer 160.

[0050] The upper main surface of the second frame 133 and the lower main surface of the third frame 143 are connected via a spacer 161. The spacer 161 has the same inner and outer diameters as the second frame 133 and the third frame 143. The thickness of the spacer 161 is approximately the same as the thickness of the second piezoelectric body 10B. The second diaphragm 12 and the third diaphragm 101 face each other via the spacer 161.

[0051] First connecting portion 122, second connecting portion 132, and third connecting portion 142 extend from the outer peripheries of first diaphragm 11, second diaphragm 12, and third diaphragm 101, respectively, and are connected to first frame 123, second frame 133, and third frame 143. First connecting portion 122, second connecting portion 132, and third connecting portion 142 elastically support first diaphragm 11, second diaphragm 12, and third diaphragm 101, respectively. First connecting portion 122, second connecting portion 132, and third connecting portion 142 are arranged at equal intervals (60-degree intervals in this third modification) from one another in a planar view, and do not overlap one another in a planar view.

[0052] As a result, actuator 2C has an area where diaphragms of opposite polarities do not overlap each other in a plan view, and therefore, when actuator 2C vibrates, the connecting portions do not come into contact with each other, thereby preventing short circuits.

[0053] The configuration in which the connecting portions connecting the diaphragm and the frame do not overlap each other in plan view is not limited to the bimorph structure, but can also be applied to a unimorph structure.

[0054] Next, Fig. 15 is an exploded perspective view showing the structure of a bimorph according to Modification 4. An actuator 2D according to Modification 4 has a rectangular shape in a plan view. Except for the rectangular shape in a plan view, actuator 2D has the same configuration and function as actuator 2C shown in Fig. 13. In this way, the actuator of the present invention may have a rectangular shape in a plan view.

[0055] 16 is an exploded perspective view of an actuator 2E according to Modification 5. The actuator 2E further includes a bonding member 81, a film valve 82, a flexible plate 83, a flow path forming member 84, and a cover member 85. The bonding member 81, the film valve 82, the flexible plate 83, the flow path forming member 84, and the cover member 85 are arranged below the first diaphragm 11 in this order. FIGS. 17 and 18 are cross-sectional views showing the first diaphragm 11 and the following portions of the actuator 2E.

[0056] The film valve 82 is made of a flexible material and has a disk shape. The film valve 82 is disposed at the center of the first diaphragm 11 in a plan view. The film valve 82 is bonded to the underside of the first diaphragm 11 via a disk-shaped bonding member 81. The outer diameter of the film valve 82 is larger than the outer diameter of the bonding member 81. In other words, the area on the outer end side of the film valve 82 is not bonded. As a result, the film valve 82 is bonded to the first diaphragm 11 in a state where a predetermined area on the outer end side is vibrable. The film valve 82 is not limited to a disk shape, and may be an annular shape.

[0057] The flexible plate 83 is a plate-shaped member having a through-hole at the center in a plan view. The flexible plate 83 is disposed at a distance from the film valve 82.

[0058] The flow path forming member 84 is a plate-like member. In the flow path forming member 84, the recess for the flow path is composed of a circular central region in a plan view and multiple linear regions. The central region overlaps with the through-hole formed in the flexible plate 83 in a plan view (viewed in the stacking direction of the flexible plate 83 and the flow path forming member 84). One end of the extending direction of the multiple linear regions is connected to the central region, and the other end reaches near different outer ends of the flow path forming member 84.

[0059] The cover member 85 is a plate-shaped member and has a plurality of holes that penetrate the cover member 85 in the thickness direction.

[0060] When the center of the first diaphragm 11 moves away from the flexible plate 83, the volume of the area sandwiched between the film valve 82 and the flexible plate 83 increases, causing a decrease in the pressure in the area sandwiched between the film valve 82 and the flexible plate 83. As a result, as shown in Figure 18, the area on the outer edge of the film valve 82 (the area on the free end side) bends toward the flexible plate 83 and abuts against the surface of the flexible plate 83. This blocks the through hole in the center of the flexible plate 83, preventing fluid from flowing into the through hole.

[0061] Therefore, the actuator 2E according to the fifth modification can improve the performance as a pump.

[0062] Next, Fig. 19 is a cross-sectional view showing the structure of bimorph modification 6. Fig. 20 is a partially enlarged view of Fig. 19 .

[0063] 6 in that it includes a circuit board, the shape of the electrode film formed on the piezoelectric body 10, and a support body 18. The other configuration of the actuator 2F is the same as that of the actuator 2, and a description of similar parts will be omitted.

[0064] The actuator 2F includes a first piezoelectric body 10A, a second piezoelectric body 10B, a second vibration plate 12F, and a support body 18.

[0065] The first piezoelectric body 10A has a principal surface F101A, a principal surface F102A, and a side surface F103A. A first electrode 14F is formed on the principal surface F101A. The first electrode 14F has a shape that does not reach the side surface F103A. A second electrode 15F is formed on the principal surface F102A and the side surface F103A. The second electrode 15F has a shape that reaches the corner where the side surface F103A and the principal surface F101A intersect.

[0066] The second piezoelectric body 10B has a principal surface F101B, a principal surface F102B, and a side surface F103B. A first electrode 151F is formed on the principal surface F101B. The first electrode 151F has a shape that does not reach the side surface F103B. A second electrode 152F is formed on the principal surface F102B and the side surface F103B. The second electrode 152F has a shape that reaches the corner where the side surface F103B and the principal surface F101B intersect.

[0067] The second diaphragm 12F is configured by a circuit board mainly made of a laminate of an insulator layer LY121 and an insulator layer LY122. The insulator layers LY121 and LY122 are flexible.

[0068] An electrode pattern D120 is formed between the insulator layer LY121 and the insulator layer LY122. Electrode patterns D122A and D122B are formed on the surface of the insulator layer LY121 opposite to the insulator layer LY122 side. Electrode patterns D123A and D123B are formed on the surface of the insulator layer LY122 opposite to the insulator layer LY121 side. The electrode pattern D122B and the electrode pattern D123A are electrically connected by a plurality of via electrodes VIA120.

[0069] The first piezoelectric element 10A is mounted on the main surface of the second vibration plate 12F facing the insulator layer LY121. The first electrode 14F of the first piezoelectric element 10A is electrically connected to the electrode pattern D122B. The second electrode 15F of the first piezoelectric element 10A is electrically connected to the electrode pattern D122A.

[0070] The second piezoelectric body 10B is mounted on the main surface of the second vibration plate 12F facing the insulator layer LY122. A first electrode 151F of the second piezoelectric body 10B is electrically connected to the electrode pattern D123B. A second electrode 152F of the second piezoelectric body 10B is electrically connected to the electrode pattern D123A.

[0071] With this configuration, an AC voltage that bimorph-drives the actuator 2F is applied to the first electrode 14F and second electrode 15F of the first piezoelectric body 10A and the first electrode 151F and second electrode 152F of the second piezoelectric body 10B.

[0072] The second vibration plate 12F protrudes outward beyond both side ends of the first piezoelectric body 10A and the second piezoelectric body 10B. These protruding portions are supported by the support body 18 at positions away from the areas of the second vibration plate 12F where the first piezoelectric body 10A and the second piezoelectric body 10B are mounted.

[0073] The second diaphragm 12F is flexible, allowing free vibration of the laminated portion of the first diaphragm 11, the first piezoelectric body 10A, the second diaphragm 12F, the second piezoelectric body 10B, and the third diaphragm 101. This allows the actuator 2F to achieve free vibration without strong constraints on the outer ends.

[0074] With this configuration, the actuator 2F can achieve the same effects as the actuator 2A. Furthermore, the actuator 2F can apply an AC voltage to the first piezoelectric body 10A and the second piezoelectric body 10B from the outside through the second diaphragm 12F. This allows the structure of the actuator 2F to be simplified, including the mechanism for applying the AC voltage.

[0075] Furthermore, it is preferable that the second diaphragm 12F have the following configuration. Fig. 21(A) is a plan view of electrode patterns D122A and D122B formed on the insulator layer LY121. Fig. 21(B) is a plan view of D123A and D123B formed on the insulator layer LY122. Fig. 22 is a plan view of electrode patterns, via electrodes, and through holes formed between the insulator layer LY121 and the insulator layer LY122. Fig. 23(A) is a plan view of the insulator layer LY121. Fig. 23(B) is a plan view of the insulator layer LY122.

[0076] 21A, the electrode pattern D122A has a circular shape in a plan view, the electrode pattern D122B has an annular shape in a plan view, and the electrode pattern D122B surrounds the electrode pattern D122A in a plan view.

[0077] 21B, the electrode pattern D123A has a circular shape in a plan view, the electrode pattern D123B has an annular shape in a plan view, and the electrode pattern D123B surrounds the electrode pattern D123A in a plan view.

[0078] The electrode pattern D122A and the electrode pattern D123A overlap when viewed in the thickness direction of the second diaphragm 12F (see FIGS. 19 and 20). The electrode pattern D122B and the electrode pattern D123B overlap when viewed in the thickness direction of the second diaphragm 12F (see FIGS. 19 and 20).

[0079] As shown in Figure 22, the electrode pattern D120 is circular in plan view. The electrode pattern D120 has an annular electrode-free portion UD120. The electrode pattern D120 includes a central portion D1201, an outer peripheral portion D1202, and a connection portion D1203. The central portion D1201 is circular in plan view. The outer peripheral portion D1202 is annular in plan view. In plan view, the outer peripheral portion D1202 surrounds the central portion D1201 with the electrode-free portion UD120 sandwiched therebetween. The outer peripheral portion D1202 has a C-ring shape with a portion cut off in the circumferential direction.

[0080] The plurality of connecting portions D1203 are arranged at predetermined intervals along the circumferential direction of the electrode-free portion UD120. The plurality of connecting portions D1203 connect the central portion D1201 and the outer peripheral portion D1202.

[0081] Wiring electrode patterns Dt1 and Dt2 are formed on the same layer as the electrode pattern D120. The wiring electrode pattern Dt1 is not connected to the electrode pattern D120, and the wiring electrode pattern Dt2 is connected to one end in the circumferential direction of the outer periphery D1202.

[0082] A via electrode VIA129 is connected to one end of the wiring electrode pattern Dt1 that enters the center of the electrode pattern D120. The via electrode VIA129 passes through the insulator layers LY121 and LY122 (see FIGS. 23A and 23B) and is connected to the electrode patterns D122A and D123A.

[0083] When viewed in the thickness direction of the second diaphragm 12F, the electrode-free portion UD120 overlaps with a plurality of through-holes TH120 formed in the insulator layers LY121 and LY122.

[0084] 23A, the insulator layer LY121 has a substantially circular shape in a plan view. The insulator layer LY121 has a plurality of via electrodes VIA120 and VIA129 formed therein. When viewed in the thickness direction of the second diaphragm 12F, the via electrodes VIA129 overlap with the electrode pattern D122A and the wiring electrode pattern Dt1.

[0085] A plurality of via electrodes VIA120 overlap the electrode pattern D122B and the electrode pattern D120.

[0086] The insulator layer LY121 includes a lead portion 121WD, which is formed by a part of a circle protruding.

[0087] 23B , the insulator layer LY122 has a substantially circular shape in a plan view. The insulator layer LY122 has a plurality of via electrodes VIA120 and VIA129 formed therein. When viewed in the thickness direction of the second diaphragm 12F, the via electrodes VIA129 overlap with the electrode pattern D123A and the wiring electrode pattern Dt1.

[0088] A plurality of via electrodes VIA120 overlap the electrode pattern D123B and the electrode pattern D120.

[0089] The insulator layer LY122 includes a lead portion 122WD. The lead portion 122WD is formed by a part of a circle protruding.

[0090] Wiring electrode patterns Dt1 and Dt2 are formed between the lead-out portions 121WD and 122WD. The lead-out portion 122WD is shorter than the lead-out portion 121WD. As a result, parts of the wiring electrode patterns Dt1 and Dt2 are exposed to the outside of the second diaphragm 12F and serve as external connection terminals.

[0091] 23A and 23B, a plurality of through holes TH120 are formed in the insulator layers LY121 and LY122. The plurality of through holes TH120 in the insulator layer LY121 communicate with the plurality of through holes TH120 in the insulator layer LY122. The plurality of through holes TH120 penetrate the second diaphragm 12F in the thickness direction.

[0092] With this configuration, the second diaphragm 12F can apply an AC voltage to the first piezoelectric body 10A and the second piezoelectric body 10B from the outside.

[0093] Furthermore, the second diaphragm 12F is provided with a plurality of through holes TH120, and thus when the actuator is in operation, air moves through the plurality of through holes TH120. This allows the function of the fluid control device including the actuator 2F to be realized.

[0094] The configuration in which a circuit board is used as a diaphragm is not limited to a bimorph structure, but can also be applied to a unimorph structure.

[0095] The description of the present embodiment should be considered to be illustrative in all respects and not restrictive. The scope of the present invention is defined not by the above-described embodiments but by the claims. Furthermore, the scope of the present invention is intended to include all modifications within the meaning and scope of the claims.

[0096] For example, in the second embodiment shown in Figure 7, in order to reverse the expansion and contraction directions of the first piezoelectric bodies 10A and 10B, the polarization directions of the piezoelectric bodies may be aligned and a driving voltage may be applied that makes the first vibration plate 11 and the third vibration plate 101 at the same potential.

[0097] Similarly, in the third modified example of the bimorph shown in Figure 13, in order to reverse the expansion and contraction directions of the first piezoelectric bodies 10A and 10B, the polarization directions of the piezoelectric bodies are aligned, and when a driving voltage is applied that makes the first vibration plate 11 and the third vibration plate 101 at the same potential, the first connecting portion 122 and the third connecting portion 142 are at the same potential and may overlap in a planar view.

[0098] 1, 2, 2A, 2B, 2C, 2D, 2E, 2F: Actuator 10: Piezoelectric body 10A: First piezoelectric body 10B: Second piezoelectric body 11: First diaphragm 12, 12F: Second diaphragm 13: Fillet 14, 14F, 151F: First electrode 15, 15F, 152F: Second electrode 18: Support 81: Bonding member 82: Film valve 83: Flexible plate 84: Flow path forming member 85: Cover member 90: Diaphragm 91: Diaphragm 101: Third diaphragm 122: First connecting portion 123: First frame 132: Second connecting portion 133: Second frame 142: Third connecting portion 143: Third frame 151: Third electrode 152: Fourth electrode 160: Spacer 161: Spacer D120, D122A, D122B, D123A, D123B: Electrode patterns D1201: Central portion D1202: Peripheral portion D1203: Connection portion Dt1, Dt2: Wiring electrode patterns F101A, F101B, F102A, F102B: Main surface F103A, F103B: Side surface LY121, LY122: Insulator layer VIA120, VIA129: Via electrode UD120: Non-electrode portion TH120: Through hole 121WD, 122WD: Lead-out portion

Claims

1. A piezoelectric body having a first main surface and a second main surface, The first electrode is arranged on the first main surface, The second electrode is positioned on the second main surface, A first diaphragm is positioned on the first electrode, A second diaphragm is positioned on the second electrode, It has, The thickness of the first diaphragm and the thickness of the second diaphragm are different. A fillet is formed between the periphery of the piezoelectric element and the first diaphragm, and between the periphery of the piezoelectric element and the second diaphragm. Actuator.

2. Viewed from above, the outer diameter of the piezoelectric element is smaller than the outer diameters of the first diaphragm and the second diaphragm. The actuator according to claim 1.

3. In a plan view, the outer diameter of the piezoelectric element is larger than the outer diameters of the first electrode and the second electrode. The actuator according to claim 1 or claim 2.

4. A first piezoelectric element having a first main surface and a second main surface, The first electrode is arranged on the first main surface, The second electrode is positioned on the second main surface, A second piezoelectric element having a third main surface and a fourth main surface, The third electrode is arranged on the third main surface, The fourth electrode is arranged on the fourth main surface, A first diaphragm is positioned on the first electrode, A second diaphragm is positioned on the second electrode and the third electrode, A third diaphragm is positioned on the fourth electrode, It has, A fillet is formed between the periphery of the first piezoelectric element and the first diaphragm, between the periphery of the first piezoelectric element and the second diaphragm, between the periphery of the second piezoelectric element and the second diaphragm, and between the periphery of the second piezoelectric element and the third diaphragm. Actuator.

5. In a plan view, the outer diameters of the first piezoelectric element and the second piezoelectric element are smaller than the outer diameters of the first diaphragm, the second diaphragm, and the third diaphragm. The actuator according to claim 4.

6. Viewed from above, the outer diameter of the second diaphragm is smaller than the outer diameters of the first and third diaphragms. The actuator according to claim 4 or claim 5.

7. In a plan view, the outer diameter of the first piezoelectric element is larger than the outer diameters of the first and second electrodes, and the outer diameter of the second piezoelectric element is larger than the outer diameters of the third and fourth electrodes. The actuator according to claim 4 or claim 5.

8. Viewed from above, the first frame, second frame, and third frame each enclose the first diaphragm, the second diaphragm, and the third diaphragm, respectively. A first connecting portion, a second connecting portion, and a third connecting portion extend from the outer circumference of each of the first diaphragm, the second diaphragm, and the third diaphragm and are connected to the first frame, the second frame, and the third frame, respectively, thereby supporting the first diaphragm, the second diaphragm, and the third diaphragm. It has, The first connecting portion, the second connecting portion, and the third connecting portion do not overlap each other when viewed from above. The actuator according to claim 4 or claim 5.

9. Viewed from above, the first diaphragm and the second diaphragm are surrounded by a first frame and a second frame, respectively. A first connecting portion and a second connecting portion extend from the outer circumference of the first diaphragm and the second diaphragm, respectively, and are connected to the first frame and the second frame to support the first diaphragm and the second diaphragm, It has, The first connecting portion and the second connecting portion do not overlap each other when viewed from above. The actuator according to claim 1 or claim 2.

10. The second diaphragm is composed of a circuit board, The circuit board comprises an insulating layer and an electrode pattern connected to the electrodes of the piezoelectric element. The actuator according to claim 1 or claim 2.

11. The second diaphragm is composed of a circuit board, The circuit board comprises an insulating layer and an electrode pattern connected to the electrodes of the first piezoelectric element and the second piezoelectric element. The actuator according to claim 4.

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