Fluid control device

Abstract

A fluid control device according to the present invention comprises an actuator and an annular frame for affixing at least a portion of the outer periphery of the actuator. The actuator comprises: a piezoelectric body that has a first main surface and a second main surface; and a vibrating plate that is connected to the first main surface of the piezoelectric body. The frame is disposed on the second main surface. The outer diameter of the vibrating plate and the outer diameter of the piezoelectric body are greater than the inner diameter of the frame, and the outer diameter of the vibrating plate or the outer diameter of the frame is greater than the outer diameter of the piezoelectric body.

Description

Fluid Control Device

[0001] The present invention relates to a fluid control device including an actuator.

[0002] Patent Document 1 discloses an actuator in which a plate-shaped piezoelectric element is attached to a plate-shaped vibration plate. The actuator is provided with a housing that covers the side surfaces of the vibration plate. This prevents the side surfaces of the piezoelectric element from coming into contact with obstacles when the actuator is dropped or transported.

[0003] Japanese Patent Application Laid-Open No. 2009-293507

[0004] In the structure of Patent Document 1, the housing is disposed on the outer side surface of the diaphragm, which increases the outer diameter of the actuator.

[0005] An object of the present invention is to provide a fluid control device that prevents the side surfaces of the piezoelectric body from coming into contact with obstacles when dropped or transported, and that can have a small outer diameter.

[0006] A fluid control device according to one embodiment of the present invention includes an actuator and an annular frame that fixes at least a portion of the outer periphery of the actuator. The actuator includes a piezoelectric body having a first main surface and a second main surface, and a vibration plate connected to the first main surface of the piezoelectric body. The frame is disposed on the second main surface. The outer diameter of the vibration plate and the outer diameter of the piezoelectric body are larger than the inner diameter of the frame, and the outer diameter of the vibration plate or the outer diameter of the frame is larger than the outer diameter of the piezoelectric body.

[0007] According to the above configuration, the outer diameter of the vibration plate and the outer diameter of the piezoelectric element are larger than the inner diameter of the frame, so that the pump chamber can be formed on the side surface of the inner periphery of the frame. Therefore, the fluid control device of this embodiment can form the pump chamber without placing a housing further outward from the piezoelectric element and the vibration plate. Furthermore, because the outer diameters of the members connected to the first and second main surfaces of the piezoelectric element are larger than the outer diameter of the piezoelectric element, obstacles and the like do not come into contact with the side surface of the piezoelectric element when dropped or transported.

[0008] According to this invention, the side surfaces of the piezoelectric body do not come into contact with obstacles when dropped or transported, and the outer diameter can be made small.

[0009] 1 is a cross-sectional view of the fluid control device 1. FIG. 2 is a plan view of the vibration plate 11. FIG. 3 is a plan view of the piezoelectric body 10. FIG. 4 is a plan view of the frame 12. FIG. 5 is a plan view of the frame 17. FIG. 6 is a cross-sectional view of the fluid control device 1 when a flat plate 83 is attached to the underside of the frame 17. FIG. 7 is a cross-sectional view of the fluid control device 1A according to Modification 1. FIG. 8 is a bottom view of the piezoelectric body 10 in the fluid control device 1A. FIG. 9 is a cross-sectional view of the vibration plate 11 in the fluid control device 1A during flexural vibration. FIG. 10 is a cross-sectional view of the fluid control device 1B according to Modification 2. FIG. 11 is a cross-sectional view of the fluid control device 2 according to the second embodiment. FIG. 12 is a cross-sectional view of the fluid control device 2 during flexural vibration. FIG. 13 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 the piezoelectric body and stress / amplitude (stress per amplitude). FIG. 14 is a diagram showing the relationship between the distance from the neutral plane of the main surface of the piezoelectric body and the amplitude. FIG. 15 is a diagram showing the relationship between the amplitude and the radial stress at the center of the piezoelectric body. FIG. 16 is a cross-sectional view showing the structure of Modification 1 of the bimorph. FIG. 17 is a cross-sectional view showing the structure of Modification 2 of the bimorph. FIG. 18 is an exploded perspective view of a fluid control device 2D according to Modification 4. 24 is a cross-sectional view showing a portion of the fluid control device 2D below the first diaphragm 11A. FIG. 25 is a cross-sectional view showing a portion of the fluid control device 2D below the first diaphragm 11A. FIG. 26 is a plan view of the fluid control device 2D. FIG. 27 is a perspective view of the fluid control device 2D. FIG. 28 is a cross-sectional view showing the structure of another modified example of the fluid control device. FIG. 29 is a partially enlarged view of FIG. 24.

[0010] A fluid control device according to a first embodiment of the present invention will be described with reference to the drawings. In each of the drawings shown in the following embodiments, the shapes of the respective components are partially or entirely exaggerated to make the description easier to understand.

[0011] 1 is a cross-sectional view of a fluid control device 1 according to a first embodiment of the present invention. The fluid control device 1 includes a piezoelectric body 10, a vibration plate 11, a frame body 12, a fillet 13, a first electrode 14, a second electrode 15, and a frame body 17.

[0012] Fig. 2 is a plan view of the vibration plate 11, Fig. 3 is a plan view of the piezoelectric body 10, Fig. 4 is a plan view of the frame body 12, and Fig. 5 is a plan view of the frame body 17. The cross-sectional view of Fig. 1 is a cross-sectional view taken along line A-A shown in Figs. 2, 3, 4, and 5.

[0013] 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 the lower surface (first principal surface) of the piezoelectric body 10 by, for example, sputtering, and a second electrode 15 is formed on the upper surface (second principal 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 planar view. While this configuration is not essential to the present invention, this configuration prevents the electrodes (first electrode 14 and second electrode 15) from protruding onto the side surfaces of the piezoelectric body 10. Therefore, the electrodes do not wrap around the side surfaces of the piezoelectric body 10 when formed, thereby suppressing short circuits.

[0014] The diaphragm 11 is attached to the first electrode 14 with an adhesive. The adhesive contains a plurality of conductive fillers. The plurality of conductive fillers become conductive to each other when the thickness of the adhesive is equal to or less than a predetermined value. Therefore, the adhesive is conductive when the thickness is equal to or less than the predetermined thickness, and is insulating when the thickness exceeds the predetermined thickness. The adhesive in the portion sandwiched between the diaphragm 11 and the first electrode 14 is equal to or less than the predetermined thickness and is conductive.

[0015] The vibration plate 11 has a disk shape. In this embodiment, the outer diameter of the piezoelectric body 10 is smaller than the outer diameter of the vibration plate 11 in a plan view.

[0016] A frame 17 is attached to the underside of the diaphragm 11 with an adhesive. The diaphragm 11 and the frame 17 are made of a conductive material. A drive circuit (not shown) is connected to the frame 17. This allows a drive voltage to be applied to the diaphragm 11 via the frame 17.

[0017] The frame 12 is attached to the second electrode 15 with an adhesive. The frame 12 is made of a conductive material. The adhesive in the portion sandwiched between the frame 12 and the second electrode 15 has a predetermined thickness or less and is conductive. A drive circuit (not shown) is connected to the frame 12. This allows a drive voltage to be applied via the frame 12.

[0018] Therefore, a drive voltage is applied to the first electrode 14 and the second electrode 15. The diaphragm 11 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.

[0019] For example, when a driving voltage that causes the piezoelectric body 10 to contract in a direction parallel to its main surface is applied, the upper surface of the diaphragm 11 contracts and the lower surface of the diaphragm 11 expands. Therefore, the lower surface of the diaphragm 11 flexes and deforms convexly downward. Furthermore, if the piezoelectric body 10 expands in a direction parallel to its main surface, the lower surface of the diaphragm 11 flexes and deforms concavely upward. This causes the diaphragm 11 to vibrate in a rotationally symmetric (concentric) manner from the center to the periphery. Therefore, the piezoelectric body 10 and the diaphragm 11 function as an actuator for a piezoelectric unimorph vibrator. The frame 12 and the frame 17 fix a portion or all of the outer periphery of the actuator. The frame 12 and the frame 17 may be annular and disposed around the entire outer periphery of the actuator in a plan view, or may be disposed around only a portion of the outer periphery in a plan view. In the structure shown in FIG. 1 , the first main surface of the actuator corresponds to the lower surface of the diaphragm 11, and the second main surface corresponds to the upper surface of the piezoelectric body 10. If the vibration plate 11 is disposed on the upper surface of the piezoelectric body 10 , the first main surface of the actuator corresponds to the lower surface of the piezoelectric body 10 , and the second main surface corresponds to the upper surface of the vibration plate 11 .

[0020] The outer diameter of the vibration plate 11 and the outer diameter of the piezoelectric body 10 are larger than the inner diameter of the frame 17. The outer diameter of the vibration plate 11 and the outer diameter of the piezoelectric body 10 are also larger than the inner diameter of the frame 12. This allows the fluid control device 1 to form a pump chamber between the inner peripheral side surface of the frame 12 or the frame 17 and the upper surface or lower surface of the actuator. Figure 6 is a cross-sectional view of the fluid control device 1 when a flat plate 83 is attached to the lower surface of the frame 17.

[0021] The flat plate 83 is a plate-like member having a circular shape in a plan view. The flat plate 83 has a through-hole at its center in a plan view. The flat plate 83 is disposed at a distance from the diaphragm 11 by the frame 17. In the structure of FIG. 6 , a pump chamber is formed in the space surrounded by the inner peripheral side surface of the frame 17, the lower surface of the diaphragm 11, and the upper surface of the flat plate 83. When the diaphragm 11 vibrates, the flat plate 83 vibrates due to pressure fluctuations in the pump chamber caused by the vibration of the diaphragm 11. The vibration phase of the flat plate 83 lags behind the vibration phase of the diaphragm 11. This substantially increases the thickness fluctuation in the gap space between the flat plate 83 and the diaphragm 11, further improving the pump's performance.

[0022] In the fluid control device 1 of this embodiment as described above, the outer diameter of the diaphragm 11 and the outer diameter of the piezoelectric body 10 are larger than the inner diameter of the frame 17, so that the inner peripheral side surface of the frame 17 can form part of the housing of the fluid control device 1. Furthermore, in the fluid control device 1, the outer diameter of the diaphragm 11 and the outer diameter of the piezoelectric body 10 are larger than the inner diameter of the frame 12, so that the inner peripheral side surface of the frame 12 can form part of the housing of the fluid control device 1. Therefore, the fluid control device 1 of this embodiment has a smaller outer diameter of the entire device than a structure in which a housing is disposed on the outer side surface of the diaphragm as in Patent Document 1 (JP 2009-293507 A).

[0023] Furthermore, the outer diameters of the components (vibration plate 11 and frame 12) connected to the first and second main surfaces of piezoelectric body 10 in fluid control device 1 of this embodiment are larger than the outer diameter of piezoelectric body 10. Therefore, in the fluid control device 1 of this embodiment, obstacles or the like do not come into contact with the side surfaces of the piezoelectric body when dropped or transported.

[0024] That is, the fluid control device 1 of this embodiment prevents the side surfaces of the piezoelectric body from coming into contact with obstacles when dropped or transported, and the outer diameter can be made small.

[0025] Furthermore, in the fluid control device 1 of this embodiment, fillets 13 are formed between the main surface of the piezoelectric body 10 and the main surface of the vibration plate 11, between the main surface of the piezoelectric body 10 and the side surface of the frame 12, and between the main surface of the vibration plate 11 and the side surface of the frame 17. The fillets 13 are formed by the above-mentioned adhesive overflow. The fillets 13 in each portion have a predetermined thickness or more and therefore have insulating properties. The fillets 13 can prevent short circuits caused by contact between the peripheral portions of the frame 12 and the vibration plate 11.

[0026] Next, Fig. 7 is a cross-sectional view of a fluid control device 1A according to Modification 1. Components common to those in Fig. 1 are given the same reference numerals and description thereof will be omitted. Fig. 8 is a bottom view of the piezoelectric body 10 in the fluid control device 1A.

[0027] In the fluid control device 1A according to the first modification, the electrode arranged on the lower surface (first main surface) is divided into an inner circumferential electrode 14A and an outer circumferential electrode 14B in plan view.

[0028] In the poling process of the piezoelectric body 10, drive voltages of opposite polarities are applied to the inner electrode 14A and the outer electrode 14B with respect to the potential of the second electrode 15. Therefore, the polarization directions of the inner and outer circumferential portions of the piezoelectric body 10 are opposite to each other.

[0029] FIG. 9 is a cross-sectional view of the diaphragm 11 of the fluid control device 1A during bending vibration. As shown in FIG. 9 , when the inner periphery of the piezoelectric element 10 expands in a direction parallel to the main surface, the inner periphery of the top surface of the diaphragm 11 bends convexly upward. Meanwhile, because at least a portion of the outer periphery of the diaphragm 11 is fixed by the frame 12 and the frame 17, the outer periphery of the top surface of the diaphragm 11 attempts to bend convexly downward, opposite to the inner periphery. If the entire piezoelectric element 10 were to expand in a direction parallel to the main surface, the outer periphery of the piezoelectric element 10 would exert a force in the opposite direction to the bending direction of the top surface of the diaphragm 11. Furthermore, although not shown, when the inner periphery of the piezoelectric element 10 contracts in a direction parallel to the main surface, the inner periphery of the top surface of the diaphragm 11 bends concavely downward, and the outer periphery of the top surface of the diaphragm 11 attempts to bend convexly upward, opposite to the inner periphery. In this case, if the entire piezoelectric body 10 were to contract in a direction parallel to the main surface, the piezoelectric body 10 would apply a force in the outer periphery in a direction opposite to the bending direction of the upper surface of the vibration plate 11.

[0030] In contrast, in the fluid control device 1A of the first modified example, the polarization directions of the inner and outer peripheral portions of the piezoelectric body 10 are opposite. Therefore, when the inner peripheral portion of the piezoelectric body 10 expands in a direction parallel to the main surface, the outer peripheral portion of the piezoelectric body 10 contracts in a direction parallel to the main surface. Furthermore, when the inner peripheral portion of the piezoelectric body 10 contracts in a direction parallel to the main surface, the outer peripheral portion of the piezoelectric body 10 expands in a direction parallel to the main surface.

[0031] Therefore, in the fluid control device 1A of the present modified example 1, the bending direction of the diaphragm and the direction of the force applied to the diaphragm by the expansion and contraction of the piezoelectric body 10 coincide with each other at the inner and outer circumferential portions, thereby enabling the fluid control device 1A of the present modified example 1 to increase the amplitude of the diaphragm 11 per unit voltage.

[0032] Next, Fig. 10 is a cross-sectional view of a fluid control device 1B according to Modification 2. The same components as those in Fig. 7 are denoted by the same reference numerals, and the description thereof will be omitted.

[0033] In the fluid control device 1B, a first vibration plate 11A is attached with an adhesive to the lower surface (first main surface) of the piezoelectric body 10, and a second vibration plate 11B is attached with an adhesive to the upper surface (second main surface) of the piezoelectric body 10. A frame 12 is attached with an adhesive to the upper surface of the second vibration plate 11B. The second vibration plate 11B is thinner than the first vibration plate 11A and is therefore more susceptible to deformation.

[0034] In the fluid control device 1B according to the second modification, when a drive voltage is applied that expands the inner peripheral portion of the piezoelectric body 10 in a direction parallel to the main surface, the center of the second diaphragm 11B is bent and deformed in a convex shape along the upper surface direction. When a drive voltage is applied that contracts the inner peripheral portion of the piezoelectric body 10 in a direction parallel to the main surface, the center of the second diaphragm 11B is bent and deformed in a concave shape along the lower surface direction.

[0035] In the fluid control device 1B of the second modification, the member bonded to the frame body 12 is the second diaphragm 11B. Therefore, the mechanical stress generated at the bonded position with the frame body 12 is mainly applied to the second diaphragm 11B, and the mechanical stress applied to the piezoelectric body 10 is reduced. In other words, in the fluid control device 1B, the mechanical stress applied to the piezoelectric body 10 due to deformation can be reduced, and cracks in the piezoelectric body 10 can be suppressed.

[0036] Next, Figure 11 is a cross-sectional view of a fluid control device 2 according to a second embodiment. The same components as those of the fluid control device 1B shown in Figure 10 are designated by the same reference numerals, and a description thereof will be omitted. The fluid control device 2 includes a first piezoelectric element 10A, a first diaphragm 11A, a second diaphragm 11B, a frame 12, a fillet 13, a first electrode 14, a second inner electrode 15A, a second outer electrode 15B, a second piezoelectric element 10B, a third diaphragm 11C, a third electrode 151, a fourth inner electrode 152A, a fourth outer electrode 152B, and a frame 17.

[0037] 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 inner electrode 152A and a fourth outer electrode 152B are formed on the fourth main surface by, for example, sputtering. A second vibration plate 11B is attached to the fourth inner electrode 152A and the fourth outer electrode 152B with an adhesive.

[0038] The second diaphragm 11B is attached with an adhesive to the third electrode 151. The third diaphragm 11C is attached with an adhesive to the fourth inner circumferential electrode 152A and the fourth outer circumferential electrode 152B.

[0039] Fillets 13 are formed between the main surface of the first vibration plate 11A and the side of the frame body 17, between the main surface of the first piezoelectric body 10A and the main surface of the first vibration plate 11A, between the main surface of the first piezoelectric body 10A and the main surface of the second vibration plate 11B, between the main surface of the second piezoelectric body 10B and the main surface of the second vibration plate 11B, between the main surface of the second piezoelectric body 10B and the main surface of the third vibration plate 11C, and between the main surface of the third vibration plate 11C and the side of the frame body 17.

[0040] The third diaphragm 11C has a disk shape. In this embodiment, the first diaphragm 11A, the second diaphragm 11B, and the third diaphragm 11C have the same shape in a plan view and the same outer diameter.

[0041] 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 11A, the second vibration plate 11B, and the third vibration plate 11C in plan view.

[0042] In this embodiment, the first diaphragm 11A, the second diaphragm 11B, and the third diaphragm 11C all have the same shape and outer diameter. The thickness of the first diaphragm 11A, the second diaphragm 11B, and the third diaphragm 11C are also the same. However, the second diaphragm 11B may be thinner or thicker than the first diaphragm 11A and the third diaphragm 11C.

[0043] A drive voltage is applied to first diaphragm 11A, second diaphragm 11B, and third diaphragm 11C. The drive voltage has a frequency that matches the resonant frequency of the actuator. The drive voltage is applied to first electrode 14, second inner electrode 15A, second outer electrode 15B, third electrode 151, fourth inner electrode 152A, and fourth outer electrode 152B.

[0044] The first piezoelectric body 10A and the second piezoelectric body 10B are polarized in opposite directions during the poling process. The inner and outer peripheral portions of the first piezoelectric body 10A are also polarized in opposite directions during the poling process. The inner and outer peripheral portions of the second piezoelectric body 10B are also polarized in opposite directions during the poling process.

[0045] Fig. 12 is a cross-sectional view of the fluid control device 2 during bending vibration. In the example of Fig. 12, the inner peripheral portion of the first piezoelectric body 10A contracts in a direction parallel to the main surface, and the outer peripheral portion of the first piezoelectric body 10A expands in a direction parallel to the main surface. Also, the inner peripheral portion of the second piezoelectric body 10B expands in a direction parallel to the main surface, and the outer peripheral portion of the first piezoelectric body 10A contracts in a direction parallel to the main surface.

[0046] In this case, the inner peripheral portion of third diaphragm 11C bends and deforms in a convex shape toward the upper surface, and the outer peripheral portion of third diaphragm 11C bends and deforms in a concave shape toward the lower surface. The inner peripheral portion of first diaphragm 11A bends and deforms in a concave shape toward the upper surface, and the outer peripheral portion of first diaphragm 11A bends and deforms in a convex shape toward the lower surface. The vertical center position of second diaphragm 11B becomes a neutral plane where the stress in the direction parallel to the main surface is approximately zero.

[0047] The outer diameter of the first diaphragm 11A, the outer diameter of the third diaphragm 11C, the outer diameter of the first piezoelectric body 10A, and the outer diameter of the second piezoelectric body 10B are larger than the inner diameters of the frame body 12 and the frame body 17. This allows the fluid control device 2 to form a pump chamber with the inner peripheral side surface of the frame body 12 or the frame body 17 and the lower surface of the first diaphragm 11A or the upper surface of the third diaphragm 11C.

[0048] Diaphragms are disposed on both main surfaces of each of the first piezoelectric element 10A and the second piezoelectric element 10B of the fluid control device 2. Therefore, even if the amplitude of the actuator is increased to increase output, there is no risk of the piezoelectric element cracking. In particular, in a plan view of the fluid control device 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 diaphragm 11A and the third diaphragm 11C. 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 device is dropped or transported, further reducing the risk of breakage.

[0049] Furthermore, in the fluid control device 2 of this embodiment, fillets 13 are formed between the main surface of the first diaphragm 11A and the side surface of the frame 17, between the main surface of the first piezoelectric body 10A and the main surface of the first diaphragm 11A, between the main surface of the first piezoelectric body 10A and the main surface of the second diaphragm 11B, between the main surface of the second piezoelectric body 10B and the main surface of the second diaphragm 11B, between the main surface of the second piezoelectric body 10B and the main surface of the third diaphragm 11C, and between the main surface of the third diaphragm 11C and the side surface of the frame 12. The fillets 13 are formed by the overflow of the adhesive described above. This prevents contact and short circuits between the peripheral portions of the first diaphragm 11A, the second diaphragm 11B, and the third diaphragm 11C.

[0050] The fluid control device 2 constitutes an actuator for a piezoelectric bimorph vibrator. Compared to the fluid control devices 1, 1A, and 1B that constitute actuators for a piezoelectric unimorph vibrator, the actuator for a piezoelectric bimorph vibrator can efficiently convert the same driving voltage into bending vibration, and can increase the amplitude per voltage.

[0051] FIG. 13 is a diagram showing the relationship between the distance from the neutral plane of the piezoelectric body's main surface (the main surface away from the neutral plane) and stress / amplitude (stress per amplitude), and FIG. 14 is a diagram showing the relationship between the distance from the neutral plane of the piezoelectric body's main surface and amplitude. FIG. 15 is a diagram showing the relationship between amplitude and radial stress at the center of the piezoelectric body. The stress shown in FIG. 13 is the stress generated in the tangential direction from the main surface of the piezoelectric body at the center position when viewed in a plane. The stress shown in FIG. 15 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. 13, 14, and 15 corresponds to the structure of the fluid control device 1B, and the bimorph corresponds to the structure of the fluid control device 2. In all cases, the thickness of the diaphragm is adjusted so that the resonant frequency of the actuator is constant.

[0052] As shown in Fig. 13, 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 (it is smaller in the bimorph). On the other hand, for the same distance from the neutral plane of the piezoelectric body's main surface, as shown in Fig. 14, the bimorph's amplitude as an actuator is much greater. Furthermore, for the same value of radial stress at the center of the piezoelectric body, as shown in Fig. 15, the bimorph's amplitude as an actuator is much greater.

[0053] In a unimorph, vibration plates are attached to both main surfaces of the piezoelectric body, inhibiting bending vibration and increasing the stretching 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.

[0054] Therefore, in a bimorph such as the fluid control device 2, the piezoelectric element is less likely to break when the output is increased and the amplitude is made larger than in a unimorph such as the fluid control devices 1, 1A, and 1B.

[0055] Next, Fig. 16 is a cross-sectional view showing the structure of a first variation of the bimorph. In the fluid control device 2A according to the first variation of Fig. 16, the outer diameters of the first piezoelectric element 10A and the second piezoelectric element 10B are larger than the outer diameter of the second diaphragm 11B in a plan view. This allows the first piezoelectric element 10A to be located between the end of the first diaphragm 11A and the end of the second diaphragm 11B, and the second piezoelectric element 10B to be located between the end of the third diaphragm 11C and the end of the second diaphragm 11B. This further reduces the possibility of contact between the first diaphragm 11A and the second diaphragm 11B and between the third diaphragm 11C and the second diaphragm 11B during vibration, thereby further suppressing the possibility of a short circuit.

[0056] Next, Fig. 17 is a cross-sectional view showing the structure of bimorph Modification 2. In a fluid control device 2B according to Modification 2 of Fig. 17, the first piezoelectric body 10A, the second piezoelectric body 10B, the first diaphragm 11A, the second diaphragm 11B, and the third diaphragm 11C all have the same outer diameter in plan view.

[0057] In the fluid control device 2B as well, fillets 13 are formed between the main surface of the first vibration plate 11A and the side surface of the frame 17, between the main surface of the first piezoelectric body 10A and the main surface of the first vibration plate 11A, between the main surface of the first piezoelectric body 10A and the main surface of the second vibration plate 11B, between the main surface of the second piezoelectric body 10B and the main surface of the second vibration plate 11B, between the main surface of the second piezoelectric body 10B and the main surface of the third vibration plate 11C, and between the main surface of the third vibration plate 11C and the side surface of the frame 12. In the fluid control device 2B as well, vibration plates are disposed on both main surfaces of the first piezoelectric body 10A and the 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.

[0058] Next, Fig. 18 is an exploded perspective view showing the structure of Modified Example 3 of the bimorph. A fluid control device 2C according to Modified Example 3 has a rectangular shape in a plan view. The fluid control device 2C has the same configuration and function as the fluid control device 2B shown in Fig. 17, except for the rectangular shape in a plan view. In this way, the fluid control device of the present invention may have a rectangular shape in a plan view.

[0059] Next, Fig. 19 is an exploded perspective view of a fluid control device 2D according to Modification 4. The fluid control device 2D further includes a bonding member 81, a film valve 82, a flat plate 83, a flow path forming member 84, a cover member 85, and a cap 90. The bonding member 81, the film valve 82, the flat plate 83, the flow path forming member 84, and the cover member 85 are arranged below the first diaphragm 11A in this order. Figs. 20 and 21 are cross-sectional views showing the portion of the fluid control device 2D below the first diaphragm 11A. Note that the cover member 85 is not shown in Figs. 20 and 21.

[0060] 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 11A in a plan view. The film valve 82 is bonded to the underside of the first diaphragm 11A 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 11A 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.

[0061] The flat plate 83 is a plate-shaped member. The flat plate 83 has through holes at the center and near the outer periphery in plan view. The flat plate 83 is disposed at a distance from the film valve 82. As described in FIG. 6 , the flat plate 83 is flexible, and vibrates due to pressure fluctuations in the pump chamber caused by vibrations of the first diaphragm 11A.

[0062] 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 flat plate 83 in a plan view (viewed in the stacking direction of the flat 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. The central region, the multiple linear regions, and the flat plate 83 form a flow path that communicates with the center of the pump chamber.

[0063] The cover member 85 is a plate-shaped member and has a hole that penetrates the cover member 85 in the thickness direction.

[0064] 21 , when the center of the first diaphragm 11A moves away from the flat plate 83, the region on the outer edge of the film valve 82 (the region on the free end side) curves toward the flat plate 83 and abuts against the surface of the flat plate 83. This blocks the flow path connecting the outer periphery of the flat plate 83 to the center, suppressing the inflow of fluid from the outer periphery of the pump chamber to the center. In this way, the film valve 82 forms a flow rectification mechanism.

[0065] Therefore, the fluid control device 2D according to the fourth modification can improve the performance as a pump.

[0066] FIG. 22 is a plan view of the fluid control device 2D, and FIG. 23 is a perspective view of the fluid control device 2D.

[0067] The cover member 85 is disposed on the bottom surface of the fluid control device 2D. The cover member 85 constitutes part of the housing of the fluid control device 2D. The cover member 85 prevents external objects from coming into direct contact with the components of the fluid control device 2D when the fluid control device 2D is dropped or transported. As a result, the cover member 85 can prevent damage to the fluid control device 2D.

[0068] The cap 90 faces the third diaphragm 11C on the opposite side from the flat plate 83. The cap 90 is placed on the top surface of the fluid control device 2D. The cap 90 prevents the third diaphragm 11C from coming into direct contact with external objects when the fluid control device 2D is dropped or transported. This makes it possible for the cap 90 to prevent damage to the fluid control device 2D.

[0069] The cap 90 has an opening 90B at its center. In plan view, the opening 90B overlaps the center of the third diaphragm 11C. This prevents the upper surface of the third diaphragm 11C from coming into contact with the cap 90 when the third diaphragm 11C is bent convexly toward the upper surface during operation. In other words, the cap 90 does not impede the vibration of the third diaphragm 11C, thereby preventing a decrease in pump performance.

[0070] The first diaphragm 11A, the second diaphragm 11B, and the third diaphragm 11C are provided with first outer peripheral terminals 110A, 111A, second outer peripheral terminals 110B, 111B, and third outer peripheral terminals 110C, 111C, respectively, which protrude outward from the outer periphery.

[0071] A drive circuit (not shown) is connected to second outer peripheral terminal 111B and frame 12. Frame 12 has bent terminal 120, and frame 17 has bent terminal 170. First diaphragm 11A and third diaphragm 11C are electrically connected via bent terminal 170 and bent terminal 120, respectively. This allows a drive voltage to be applied to first diaphragm 11A, second diaphragm 11B, and third diaphragm 11C.

[0072] The first outer terminals 110A, 111A, the second outer terminals 110B, 111B, and the third outer terminals 110C, 111C do not overlap in plan view, thereby preventing the first outer terminals 110A, 111A, the second outer terminals 110B, 111B, and the third outer terminals 110C, 111C from contacting each other and suppressing short circuits between the terminals.

[0073] Furthermore, in plan view, the outer diameter of the cover member 85, which is the housing of the fluid control device, is located outside the outermost positions of the first outer terminals 110A, 111A, the second outer terminals 110B, 111B, and the third outer terminals 110C, 111C. This allows the cover member 85 to prevent short circuits between the first outer terminals 110A, 111A, the second outer terminals 110B, 111B, and the third outer terminals 110C, 111C due to contact with or deformation of the first outer terminals 110A, 111A, the second outer terminals 110B, 111B, and the third outer terminals 110C, 111C in the event of a drop or other impact.

[0074] The bent terminals 120 and 170 can shorten the path of the terminals leading to the outside, thereby suppressing noise caused by unnecessary vibrations and deterioration of pump performance caused by vibration leakage.

[0075] The cap has a protrusion 90A that protrudes outward in a plan view. The bent terminals 120 and 170 are pressed in the vertical direction by the protrusion 90A. When the bent terminals 120 and 170 are joined, the vertical reaction force generated by the bent terminals 120 and 170 is suppressed by the protrusion 90A. This improves the strength of the joint.

[0076] Next, Fig. 24 is a cross-sectional view showing the structure of another modified example of the fluid control device, and Fig. 25 is a partially enlarged view of Fig. 24.

[0077] The fluid control device 1E according to the fourth modification differs from the fluid control device 1A shown in Fig. 7 in that it includes a circuit board and in the shape of the electrode film formed on the piezoelectric body 10. Other configurations of the fluid control device 1E are the same as those of the fluid control device 1A, and a description of similar parts will be omitted.

[0078] The fluid control device 1E includes a piezoelectric body 10, a frame body 12, a fillet 13, a frame body 17, and a circuit board 18. The piezoelectric body 10 includes a main surface F101, a main surface F102, and a side surface F103.

[0079] An inner electrode 14EA and an outer electrode 14EB are formed on the main surface F101. The outer electrode 14EB has a shape that does not reach the side surface F103.

[0080] A second electrode 15E is formed on the main surface F102 and the side surface F103. The second electrode 15E has a shape that reaches the corner where the side surface F103 and the main surface F101 intersect.

[0081] The circuit board 18 is mainly composed of a laminate of insulator layers 181 and 182. An electrode pattern D181 is formed between the insulator layers 181 and 182. An electrode pattern D1821 and an electrode pattern D1822 are formed on the surface of the insulator layer 182 opposite to the insulator layer 181 side. The electrode pattern D1821 and the electrode pattern D1822 are spaced apart from each other. The electrode pattern D1822 is electrically connected to the electrode pattern D181 through a plurality of via electrodes VIA18 formed in the insulator layer 182.

[0082] The piezoelectric body 10 is mounted on a circuit board 18. The inner electrode 14EA and the outer electrode 14EB of the piezoelectric body 10 are electrically connected to the electrode pattern D1822. The second electrode 15E of the piezoelectric body 10 is electrically connected to the electrode pattern D1821.

[0083] With this configuration, an AC voltage is applied to the inner electrode 14EA and the outer electrode 14EB of the piezoelectric body 10 through the electrode pattern D1822, the plurality of via electrodes VIA18, and the electrode pattern D181 of the circuit board 18. An AC voltage is applied to the second electrode 15E of the piezoelectric body 10 through the electrode pattern D1821.

[0084] With the above-described configuration, the circuit board 18 is a flat plate having a predetermined rigidity (elasticity). Therefore, the circuit board 18 functions as a diaphragm. This allows the fluid control device 1E to function as an actuator.

[0085] The fillet 13 covers the electrode pattern D1821 of the circuit board 18 and the side surface F103 of the side surface F103 of the piezoelectric body 10. This makes it possible to prevent a short circuit between the electrode pattern D1821 and the frame body 12.

[0086] With this configuration, the fluid control device 1E can achieve the same effects as the fluid control device 1A. Furthermore, the fluid control device 1E uses, as a diaphragm, a circuit board that applies an AC voltage to the inner electrode 14EA, the outer electrode 14EB, and the second electrode 15E of the piezoelectric body 10. This simplifies the structure of the fluid control device 1E, including the AC voltage application mechanism.

[0087] In the above-described embodiments, the inner peripheral surface of the frame is circular in plan view, but this is not limiting. For example, the inner peripheral surface of the frame may have an elliptical or regular polygonal shape in plan view. In the case of an elliptical shape, the inner diameter corresponds to the major axis, and in the case of a regular polygon, the inner diameter corresponds to the length of the diagonal.

[0088] Similarly, in each embodiment, the piezoelectric element and the diaphragm have circular outer shapes in a plan view, but this is not limiting. In this case, for example, the outer diameter corresponds to the shortest distance from the center (the center of the shape of the inner peripheral surface of the frame when viewed in a plan view) when the frame is placed on the actuator made up of the piezoelectric element and the diaphragm.

[0089] 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.

[0090] DESCRIPTION OF SYMBOLS 1, 1A, 1B, 1E, 2, 2A, 2C, 2D: Fluid control device 10: Piezoelectric element 10A: First piezoelectric element 10B: Second piezoelectric element 11: Diaphragm 11A: First diaphragm 11B: Second diaphragm 11C: Third diaphragm 12: Frame 13: Fillet 14: First electrode 14A, 14EA: Inner electrode 14B, 14EB: Outer electrode 15: Second electrode 15A: Second inner electrode 15B: Second outer electrode 17: Frame 18: Circuit board 81: Bonding member 82: Film valve 83: Flat plate 84: Flow path forming member 85: Cover member 90: Cap 90A: Protrusion 90B: Opening 110A, 111A: First outer terminal 110B, 111B: Second outer terminal 110C, 111C: Third outer peripheral terminal 120: Bent terminal 151: Third electrode 152A: Fourth inner peripheral electrode 152B: Fourth outer peripheral electrode 170: Bent terminal 181, 182: Insulator layer D1821, D1822: Electrode patterns VIA18: Via electrode

Claims

1. Actuator and An annular frame is placed on the actuator and fixes at least a portion of the outer circumference of the actuator, Equipped with, The actuator comprises a piezoelectric body having a first main surface and a second main surface, and a diaphragm connected to the first main surface of the piezoelectric body. The frame is arranged on the second main surface, The outer diameter of the diaphragm and the outer diameter of the piezoelectric element are larger than the inner diameter of the frame. The outer diameter of the diaphragm or the outer diameter of the frame is greater than the outer diameter of the piezoelectric element. Fluid control device.

2. A fillet is formed between the side surface of the frame and the second main surface of the piezoelectric element, or between the side surface of the frame and the main surface of the diaphragm. The fluid control device according to claim 1.

3. The electrode arranged on the first main surface of the piezoelectric body or the electrode arranged on the second main surface of the piezoelectric body is divided into an inner electrode and an outer electrode when viewed from above. A fluid control device according to claim 1 or claim 2.

4. Actuator and An annular frame is placed on the actuator and fixes at least a portion of the outer circumference of the actuator, Equipped with, The actuator comprises a piezoelectric body having a first main surface and a second main surface, and a diaphragm connected to the piezoelectric body. The diaphragm comprises a first diaphragm connected to the first main surface and a second diaphragm connected to the second main surface. The frame is arranged on the side of the first diaphragm or the second diaphragm opposite to the piezoelectric element. The outer diameter of the first diaphragm, the outer diameter of the second diaphragm, and the outer diameter of the piezoelectric element are larger than the inner diameter of the frame. The outer diameter of the first diaphragm, the outer diameter of the second diaphragm, or the outer diameter of the frame is greater than the outer diameter of the piezoelectric element. Fluid control device.

5. A fillet is formed between the side surface of the frame and the main surface of the first diaphragm, or between the side surface of the frame and the main surface of the second diaphragm. The fluid control device according to claim 4.

6. The electrode arranged on the first main surface of the piezoelectric body or the electrode arranged on the second main surface of the piezoelectric body is divided into an inner electrode and an outer electrode when viewed from above. The fluid control device according to claim 4 or claim 5.

7. The piezoelectric body includes a first piezoelectric body having the first main surface and the second main surface, and a second piezoelectric body having the third main surface and the fourth main surface. The second diaphragm is further arranged on the third main surface, The diaphragm further includes a third diaphragm disposed on the fourth main surface, The frame comprises a first frame connected to the first diaphragm and a second frame connected to the third diaphragm. The fluid control device according to claim 4 or claim 5.

8. 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 fluid control device according to claim 7.

9. Viewed from above, the outer diameter of the second diaphragm is smaller than the outer diameters of the first and third diaphragms. The fluid control device according to claim 7.

10. A flat plate facing the first diaphragm is provided, The fluid control device according to claim 7.

11. A rectifier mechanism is disposed between the flat plate and the first diaphragm. The fluid control device according to claim 10.

12. The cap is provided on the opposite side of the flat plate and facing the third diaphragm, The fluid control device according to claim 10.

13. The cap has an opening. The fluid control device according to claim 12.

14. The first diaphragm, the second diaphragm, and the third diaphragm are each provided with a first outer peripheral terminal, a second outer peripheral terminal, and a third outer peripheral terminal that protrude from the outer peripheral side of the first diaphragm, the second diaphragm, and the third diaphragm, respectively. The first outer terminal, the second outer terminal, and the third outer terminal do not overlap when viewed from above. The fluid control device according to claim 7.

15. Viewed from above, the outer diameter of the housing of the fluid control device is located outside the outermost positions of the first outer terminal, the second outer terminal, and the third outer terminal. The fluid control device according to claim 14.

16. The first frame or the second frame has a bending terminal, The first diaphragm and the third diaphragm are electrically connected via the bending terminal. The fluid control device according to claim 7.

17. The aforementioned fluid control device is A flat plate facing the first diaphragm, The system comprises a cap facing the third diaphragm on the opposite side of the flat plate, The aforementioned cap has a projection that protrudes outward when viewed from above, The aforementioned bent terminal is held in place by the aforementioned protruding portion. The fluid control device according to claim 16.

18. The pump chamber is formed by the space enclosed by the inner side surface of the frame, the first diaphragm, and the surface facing the first diaphragm. The fluid control device according to claim 7.

19. The 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. A fluid control device according to claim 1 or claim 2.