Piezoelectric actuator, ultrasonic element, ultrasonic device, and electronic device

Abstract

A piezoelectric actuator, an ultrasonic element, an ultrasonic device, and an electronic device that can suppress vibration of unnecessary frequencies. The piezoelectric actuator includes: a vibrating plate having a first surface that closes an opening provided in a substrate and a second surface provided with a plurality of piezoelectric elements; a suppressing portion that suppresses vibration of the vibrating plate; and a first standing wall and a second standing wall that extend from the first surface to the opening. When a portion where a first electrode, a piezoelectric body layer, and a second electrode are overlapped is an active portion of the piezoelectric element, when viewed from above in the stacking direction of the first electrode, the piezoelectric body layer, and the second electrode, the first standing wall and the second standing wall are provided so as to sandwich the active portion, and the second standing wall is different from the first standing wall in at least one of width, height, length, and physical properties.

Description

Technical Field

[0001] The present invention relates to a piezoelectric actuator, an ultrasonic element, an ultrasonic probe, an ultrasonic device, and an electronic device. Background Art

[0002] Conventionally, as shown in Patent Document 1, there is known an ultrasonic sensor including a substrate having an opening, a diaphragm provided on the substrate so as to block the opening, and a plurality of piezoelectric elements including a first electrode, a piezoelectric layer, and a second electrode laminated on the opposite side of the opening of the diaphragm. When a portion where the first electrode, the piezoelectric layer, and the second electrode are completely overlapped in the lamination direction of the first electrode, the piezoelectric layer, and the second electrode is an active portion, a vibration suppressing portion for suppressing the vibration of the diaphragm and a partition wall surrounding the opening are provided between adjacent active portions.

[0003] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2015 - 188208

[0004] In the above structure, the partition walls surrounding the opening have the same shape and physical properties. Therefore, there is a problem that when the vibration of the diaphragm is transmitted to the partition wall, the partition wall easily resonates and unnecessary frequency vibrations caused by the resonance of the partition wall occur. Summary of the Invention

[0005] A piezoelectric actuator includes: a substrate having an opening; a diaphragm provided on the substrate so as to block the opening with a first surface; a piezoelectric element provided corresponding to the opening on a second surface of the diaphragm opposite to the first surface; a vibration suppressing portion for suppressing the vibration of the diaphragm; a first vertical wall extending from the first surface toward the opening; and a second vertical wall extending from a position different from the first vertical wall on the first surface toward the opening. The piezoelectric element laminates a first electrode, a piezoelectric layer, and a second electrode in this order from the second surface side. When a portion where the first electrode, the piezoelectric layer, and the second electrode are overlapped is an active portion, when viewed from above in the lamination direction, the first vertical wall and the second vertical wall are provided so as to sandwich the active portion, and the second vertical wall is different from the first vertical wall in at least one of width, height, length, and physical properties.

[0006] An ultrasonic element includes the piezoelectric actuator described above; a transmission circuit for transmitting ultrasonic waves to the piezoelectric actuator; and a reception circuit for receiving ultrasonic waves from the piezoelectric actuator.

[0007] An ultrasonic probe includes the ultrasonic element described above and a housing for housing the ultrasonic element.

[0008] An ultrasonic device includes the ultrasonic element described above and a control portion for controlling the ultrasonic element.

[0009] The electronic device includes the piezoelectric actuator described above. Description of the Drawings

[0010] Figure 1 It is a perspective view showing the schematic structure of the ultrasonic measurement device according to Embodiment 1.

[0011] Figure 2 It is a block diagram showing the schematic structure of the ultrasonic measurement device according to Embodiment 1.

[0012] Figure 3 It is a perspective view showing the schematic structure of the piezoelectric actuator according to Embodiment 1.

[0013] Figure 4 It is a top view of the piezoelectric actuator according to Embodiment 1 as viewed from the base side.

[0014] Figure 5 It is a top view of the piezoelectric actuator according to Embodiment 1 as viewed from the sealing plate side.

[0015] Figure 6 It is Figure 4 A cross-sectional view taken along line A-A in

[0016] Figure 7 It is Figure 4 A cross-sectional view taken along line B-B in

[0017] Figure 8 It is a top view of the piezoelectric actuator according to the comparative example as viewed from the base side.

[0018] Figure 9 It is Figure 8 A cross-sectional view taken along line C-C in

[0019] Figure 10 It is a graph showing the frequency spectrum of the piezoelectric actuator according to the comparative example.

[0020] Figure 11 It is a graph showing the frequency spectrum of the piezoelectric actuator according to Embodiment 1.

[0021] Figure 12 It is a top view of the piezoelectric actuator according to Embodiment 2 as viewed from the base side.

[0022] Figure 13 It is Figure 12 A cross-sectional view taken along line E-E in

[0023] Figure 14 It is a top view of the piezoelectric actuator according to Embodiment 3 as viewed from the base side.

[0024] Figure 15It is a plan view of the piezoelectric actuator according to Embodiment 4, observed from the base side.

[0025] Figure 16 It is a plan view of the piezoelectric actuator according to Embodiment 5, observed from the base side.

[0026] Figure 17 It is a plan view of the piezoelectric actuator according to Embodiment 6, observed from the base side.

[0027] Figure 18 It is Figure 17 a cross-sectional view taken along line F-F in

[0028] Figure 19 It is a plan view of the piezoelectric actuator according to Embodiment 7, observed from the base side.

[0029] Figure 20 It is a plan view of the piezoelectric actuator according to Embodiment 7, observed from the sealing plate side.

[0030] Figure 21 It is Figure 19 a cross-sectional view taken along line G-G in

[0031] Figure 22 It is a plan view of the piezoelectric actuator according to Embodiment 8, observed from the base side.

[0032] Figure 23 It is Figure 22 a cross-sectional view taken along line H-H in

[0033] Figure 24 It is a plan view of the piezoelectric actuator according to Embodiment 9, observed from the base side.

[0034] Figure 25 It is a plan view of the piezoelectric actuator according to Embodiment 10, observed from the base side.

[0035] Explanation of reference numerals

[0036] 1…Ultrasonic measurement device as an ultrasonic device and an electronic device; 2…Ultrasonic probe; 3…Cable; 10…Control unit; 11…Operation unit; 12…Display unit; 13…Storage unit; 14…Arithmetic unit; 21…Housing; 22, 22a~22h, 22k, 22m…Piezoelectric actuator; 23…Circuit board; 24…Ultrasonic element; 41…Base; 42…Sealing plate; 43, 43A, 43B…Suppression unit; 231…Selection circuit; 232…Transmission circuit; 233…Reception circuit; 411…Substrate; 411A…Opening; 412…Vibration plate; 412h…First surface; 412r…Second surface; 413…Piezoelectric element; 413A…Active part; 414…First electrode; 414P…First electrode terminal; 415…Piezoelectric body layer; 416…Second electrode; 416P…Second electrode terminal; 418, 418a~418h, 418k, 418m…First vertical wall; 419, 419a~419h, 419k, 419m, 420c, 420f, 420k…Second vertical wall; H1, H2…Height; L1, L2, L2a, L2b…Length; W1, W2…Width. Detailed implementation manners

[0037] 1. Embodiment 1

[0038] Refer to Figure 1 and Figure 2 , and describe the ultrasonic measurement device 1 according to Embodiment 1.

[0039] As Figure 1 and Figure 2 shown, the ultrasonic measurement device 1 as an ultrasonic device and an electronic device in this embodiment has an ultrasonic probe 2 and a control unit 10 electrically connected to the ultrasonic probe 2 via a cable 3.

[0040] The ultrasonic measurement device 1 brings the ultrasonic probe 2 into contact with the surface of a living body such as a human body, transmits ultrasonic waves from the ultrasonic probe 2, and receives the ultrasonic waves reflected in the living body through the ultrasonic probe 2. Based on the received signal, an internal tomographic image of the living body can be obtained, and the state of organs in the living body such as blood flow can be measured.

[0041] The ultrasonic probe 2 has an ultrasonic element 24 and a housing 21 that houses the ultrasonic element 24.

[0042] The ultrasonic element 24 has a piezoelectric actuator 22 and a circuit board 23 that controls the piezoelectric actuator 22.

[0043] The circuit board 23 has a transmission circuit 232 for transmitting ultrasonic waves from the piezoelectric actuator 22, a reception circuit 233 for receiving ultrasonic waves by the piezoelectric actuator 22 and outputting a received signal, and a selection circuit 231.

[0044] Under the control of the control unit 10, the selection circuit 231 switches between a transmission connection connecting the piezoelectric actuator 22 and the transmission circuit 232, and a reception connection connecting the piezoelectric actuator 22 and the reception circuit 233.

[0045] When switched to the transmission connection, the transmission circuit 232 outputs a transmission signal for causing the piezoelectric actuator 22 to emit ultrasonic waves via the selection circuit 231.

[0046] When switched to the reception connection, the reception circuit 233 outputs the reception signal input from the piezoelectric actuator 22 via the selection circuit 231 to the control unit 10. After performing various signal processes such as converting the reception signal into a digital signal, removing noise components, and amplifying to a desired signal level, etc., the reception circuit 233 outputs the processed reception signal to the control unit 10.

[0047] The housing 21 is formed in a rectangular box shape, for example. One surface of the housing 21 becomes the sensor surface 21A, and a sensor window 21B is provided on the sensor surface 21A. A part of the piezoelectric actuator 22 is exposed from the sensor window 21B. In addition, a through hole 21C for the cable 3 is provided in a part of the housing 21, and the cable 3 is connected to the circuit board 23 from the through hole 21C.

[0048] The control unit 10 includes an operation unit 11, a display unit 12, a storage unit 13, and an arithmetic unit 14. The control unit 10 controls the ultrasonic element 24. The control unit 10 can use a general terminal device such as a smart phone or a personal computer, or a dedicated terminal device for operating the ultrasonic probe 2, for example.

[0049] The operation unit 11 is a user interface for operating the ultrasonic measurement device 1, and can use a touch panel provided on the display unit 12, operation buttons, etc., for example. The display unit 12 is constituted by a liquid crystal display, etc., and displays an image. The storage unit 13 stores various programs and various data for controlling the ultrasonic measurement device 1. The arithmetic unit 14 is constituted by an arithmetic circuit such as a CPU and a storage circuit such as a memory, for example. The arithmetic unit 14 controls the process of generating and outputting a transmission signal by the transmission circuit 232, and controls the frequency setting and gain setting, etc. of the reception signal by the reception circuit 233 by reading and executing various programs stored in the storage unit 13.

[0050] Refer to Figures 3 to 7 and Figure 11 The piezoelectric actuator 22 according to Embodiment 1 will be described. As will be described later, the width W1 of the first vertical wall 418 of the piezoelectric actuator 22 is different from the width W2 of the second vertical wall 419. It should be noted that, for the convenience of explaining the internal structure of the piezoelectric actuator 22, Figure 5Shows the state after the sealing plate 42 is removed. In addition, for ease of explanation in the drawings, the dimensional ratios of the respective components are different from the actual ones.

[0051] In the coordinates of the attached notes of the drawings, three mutually orthogonal axes are described as the X-axis, Y-axis, and Z-axis. The direction along the X-axis is set as the "X direction", the direction along the Y-axis is set as the "Y direction", the direction along the Z-axis is set as the "Z direction", and the direction of the arrow is the positive direction. In addition, when observing from the Z direction in plan view, the surface on the positive side of the Z direction is defined as the upper surface, and the surface on the negative side of the Z direction on the opposite side is defined as the lower surface for explanation.

[0052] As Figure 3 shown, the piezoelectric actuator 22 includes a base 41, a sealing plate 42, and a restraining portion 43.

[0053] As Figure 3 , Figure 4 and Figure 6 shown, the base 41 has: a substrate 411 formed with an opening 411A, a diaphragm 412 closing the opening 411A, a plurality of piezoelectric elements 413 provided on the diaphragm 412, a first vertical wall 418 provided on the diaphragm 412, and a second vertical wall 419 provided on the diaphragm 412. In addition, an acoustic matching layer, an acoustic lens, etc. may be provided in the opening 411A of the substrate 411.

[0054] The substrate 411 is a semiconductor substrate such as silicon. In the present embodiment, the substrate 411 is made of silicon. When observing from the Z direction in plan view, the substrate 411 has an opening 411A at its central portion.

[0055] The diaphragm 412 is a thin film made of, for example, a laminate of silicon oxide, silicon oxide, and zirconia. The diaphragm 412 has a first surface 412h and a second surface 412r on the side opposite to the first surface 412h. The first surface 412h is the upper surface of the diaphragm 412, and the second surface 412r is the lower surface of the diaphragm 412. The diaphragm 412 is provided on the lower surface of the substrate 411, and the first surface 412h of the diaphragm 412 closes the opening 411A from the lower surface side of the substrate 411.

[0056] As Figure 3 , Figure 4 and Figure 6 shown, the first vertical wall 418 is provided on the first surface 412h of the diaphragm 412 and extends from the first surface 412h toward the opening 411A. In the present embodiment, when observing from the Z direction in plan view, the first vertical wall 418 extends parallel to the X direction. In addition, the end portions on the positive side and negative side of the X direction of the first vertical wall 418 are respectively connected to the peripheries on the positive side and negative side of the X direction of the opening 411A.

[0057] The second vertical wall 419 is provided on the first surface 412h of the vibrating plate 412 and extends from a position different from that of the first vertical wall 418 toward the opening 411A on the first surface 412h. In the present embodiment, the second vertical wall 419 extends parallel to the X direction when viewed from above in the Z direction, and the first vertical wall 418 and the second vertical wall 419 are arranged at positions adjacent to each other side by side in the Y direction. In addition, the end portions on the positive X direction side and the negative X direction side of the second vertical wall 419 are respectively connected to the peripheries on the positive X direction side and the negative X direction side of the opening 411A.

[0058] In the present embodiment, when viewed from above in the Z direction, the first vertical wall 418 and the second vertical wall 419 are alternately arranged side by side in the Y direction and function as partition walls that divide the opening 411A.

[0059] It should be noted that, in the present embodiment, the first vertical wall 418 and the second vertical wall 419 are formed by patterning the substrate 411 using a photolithography technique. Thus, the first vertical wall 418 and the second vertical wall 419 can be formed of the same material as the substrate 411. For example, by using a silicon substrate as the substrate 411, the first vertical wall 418 and the second vertical wall 419 can be made of silicon. In this way, by making the materials of the first vertical wall 418 and the second vertical wall 419 the same as each other, the physical properties of the first vertical wall 418 can be made substantially the same as those of the second vertical wall 419.

[0060] Here, when viewed from above in the Z direction, the distance from the positive Y direction edge to the negative Y direction edge of the first vertical wall 418 is the width W1 of the first vertical wall 418, and the distance from the positive X direction end portion to the negative X direction end portion of the first vertical wall 418 is the length L1 of the first vertical wall 418. In addition, when viewed from above in the X direction, the distance from the first surface 412h of the vibrating plate 412 corresponding to the lower surface of the first vertical wall 418 to the upper surface of the first vertical wall 418 is the height H1 of the first vertical wall 418.

[0061] Similarly, when viewed from above in the Z direction, the distance from the positive Y direction edge to the negative Y direction edge of the second vertical wall 419 is the width W2 of the second vertical wall 419, and the distance from the positive X direction end portion to the negative X direction end portion of the second vertical wall 419 is the length L2 of the second vertical wall 419. In addition, when viewed from above in the X direction, the distance from the first surface 412h of the vibrating plate 412 corresponding to the lower surface of the second vertical wall 419 to the upper surface of the second vertical wall 419 is the height H2 of the second vertical wall 419.

[0062] In the present embodiment, the width W1 of the first vertical wall 418 is different from the width W2 of the second vertical wall 419. Specifically, the width W1 of the first vertical wall 418 is greater than the width W2 of the second vertical wall 419. The length L1 of the first vertical wall 418 is substantially equal to the length L2 of the second vertical wall 419. The height H1 of the first vertical wall 418 is substantially equal to the height H2 of the second vertical wall 419. It should be noted that "substantially" means including manufacturing errors and dimensional tolerances, etc.

[0063] Thus, since the width W2 of the second vertical wall 419 is different from the width W1 of the first vertical wall 418, the first vertical wall 418 and the second vertical wall 419 have different vibration characteristics respectively. Specifically, since the first vertical wall 418 and the second vertical wall 419 have different resonance frequencies respectively, the vibrations of the first vertical wall 418 and the second vertical wall 419 are difficult to combine, and when the vibration of the vibration plate 412 is transmitted to the first vertical wall 418 and the second vertical wall 419, the resonance intensities of the first vertical wall 418 and the second vertical wall 419 become smaller respectively.

[0064] As Figure 4 , Figure 6 and Figure 7 shown, on the second surface 412r of the vibration plate 412 on the side opposite to the first surface 412h, a piezoelectric element 413 is provided corresponding to the opening 411A of the substrate 411. Specifically, the piezoelectric element 413 is arranged to overlap the opening 411A when viewed from above in the Z direction. In addition, the piezoelectric element 413 is arranged to be sandwiched between the first vertical wall 418 and the second vertical wall 419 that function as partition walls dividing the opening 411A.

[0065] As Figures 5 to 7 shown, the piezoelectric element 413 is a laminate formed by laminating a first electrode 414, a piezoelectric layer 415, and a second electrode 416. The first electrode 414, the piezoelectric layer 415, and the second electrode 416 are laminated in this order from the side of the second surface 412r of the vibration plate 412. When viewed from above in the Z direction, which is the lamination direction of the first electrode 414, the piezoelectric layer 415, and the second electrode 416, the overlapping portion of the first electrode 414, the piezoelectric layer 415, and the second electrode 416 functions as an active part 413A.

[0066] The first electrode 414 extends in the X direction and is continuously provided on a plurality of active parts 413A. The ends of the plurality of first electrodes 414 arranged in the Y direction on the positive X side and the negative X side are electrically connected to the first electrode terminals 414P provided on the outer peripheries of the substrate 411 on the positive Y side and the negative Y side.

[0067] When viewed from above in the Z direction, the piezoelectric layers 415 are arranged in a matrix corresponding to the crossing positions of the first electrode 414 and the second electrode 416. As the piezoelectric layer 415, a composite oxide having a perovskite structure of lead zirconate titanate can be typically used. Accordingly, it is easy to ensure the displacement amount of the piezoelectric element 413. In addition, as the piezoelectric layer 415, a composite oxide having a perovskite structure without lead can also be used. Accordingly, the piezoelectric actuator 22 can be realized using a lead-free material with a small environmental burden.

[0068] The second electrode 416 extends in the Y direction and is continuously provided on the plurality of active parts 413A. The ends on the positive Y side and the negative Y side of the plurality of second electrodes 416 arranged in the X direction are led out to the outer peripheral edges on the positive X side and the negative X side of the substrate 411. The ends of the second electrode 416 led out to the outer peripheral edge of the substrate 411 are wired and electrically connected to the second electrode terminals 416P provided on the outer peripheral edges on the positive X side and the negative X side of the substrate 411.

[0069] As long as the first electrode 414 and the second electrode 416 have conductivity, there is no limitation on their materials. As the materials of the first electrode 414 and the second electrode 416, for example, a conductive layer such as iridium, platinum, or titanium can be used. In addition, the conductive layer can be a single layer or a multilayer.

[0070] The plurality of piezoelectric elements 413 are arranged in a matrix in the X direction and the Y direction. The X direction is along the X axis, that is, the first axis orthogonal to the stacking direction in the active part 413A, which is the Z direction, of the first electrode 414, the piezoelectric layer 415, and the second electrode 416. The Y direction is along the Y axis, that is, the second axis orthogonal to the X axis as the first axis. In the present embodiment, one transmission / reception column is formed by arranging a plurality of piezoelectric elements 413 side by side in the X direction, and a matrix of a plurality of piezoelectric elements 413 is formed by arranging a plurality of transmission / reception columns side by side in the Y direction.

[0071] As Figure 4 , Figure 5 and Figure 7 shown, the suppression part 43 is provided on the second surface 412r of the diaphragm 412. The upper surface of the suppression part 43 is joined to the second surface 412r of the diaphragm 412, and the lower surface of the suppression part 43 is joined to the sealing plate 42. Accordingly, the suppression part 43 can fix the diaphragm 412 and suppress the vibration of the diaphragm 412.

[0072] The suppression part 43 is provided corresponding to the active part 413A. Specifically, as Figure 4 and Figure 5As shown, when viewed from above in the Z direction, the suppression portions 43 extend parallel to the Y direction, and a plurality of suppression portions 43 are arranged side by side in the X direction. Moreover, a plurality of piezoelectric elements 413 arranged side by side in the Y direction are arranged between the plurality of suppression portions 43. In other words, the suppression portions 43 are arranged so as to sandwich the active portion 413A in the X direction when viewed from above in the Z direction, which is the stacking direction of the first electrode 414, the piezoelectric layer 415, and the second electrode 416 in the active portion 413A.

[0073] In addition, as Figure 4 and Figure 6 shown, the first vertical wall 418 and the second vertical wall 419 are arranged so as to sandwich the active portion 413A in the Y direction when viewed from above in the Z direction, which is the stacking direction of the first electrode 414, the piezoelectric layer 415, and the second electrode 416 in the active portion 413A.

[0074] That is, on the positive side and the negative side in the X direction of the active portion 413A, the suppression portions 43 are arranged on the diaphragm 412, and on the positive side and the negative side in the Y direction of the active portion 413A, the first vertical wall 418 and the second vertical wall 419 are arranged on the diaphragm 412. In this way, the vibration ranges of the diaphragm 412 in the X direction and the Y direction can be restricted by the suppression portions 43, the first vertical wall 418, and the second vertical wall 419.

[0075] The suppression portion 43 is made of, for example, a resin material, and a photosensitive resin material can be coated on the diaphragm 412 by spin coating, sputtering, etc., and then patterned using photolithography technology to form it.

[0076] It should be noted that in the present embodiment, as described above, the suppression portion 43 is provided on the second surface 412r of the diaphragm 412, but the suppression portion 43 can also be provided on the first surface 412h of the diaphragm 412. However, providing the suppression portion 43 on the second surface 412r of the diaphragm 412 can more easily suppress the vibration of the diaphragm 412.

[0077] As Figure 3 , Figure 6 and Figure 7 shown, when viewed from above in the Z direction, the sealing plate 42 is formed in substantially the same shape as the substrate 411. The sealing plate 42 is disposed opposite to the second surface 412r of the diaphragm 412. The upper surface of the sealing plate 42 is joined to the lower surface of the substrate 411 via the diaphragm 412. The sealing plate 42 has a recess 42A that is recessed downward at the central portion of the upper surface when viewed from above in the Z direction. The piezoelectric elements 413 provided on the second surface 412r of the diaphragm 412 are sealed in the space S formed by the recess 42A.

[0078] As Figure 3 and Figure 5As shown, the sealing plate 42 has through-holes 42B at positions corresponding to the first electrode terminal 414P and the second electrode terminal 416P. For example, wiring members (not shown) such as FPC (Flexible Printed Circuits) are inserted through the through-holes 42B. The first electrode terminal 414P and the second electrode terminal 416P are electrically connected to the circuit board 23 via the wiring members (not shown).

[0079] When transmitting ultrasonic waves, a drive signal is input from the circuit board 23 to the first electrode terminal 414P via the wiring members (not shown), and a common bias signal is input to the second electrode terminal 416P. By controlling the signal intensity and signal input timing of the drive signal input to the first electrode terminal 414P, a potential difference is generated between the first electrode 414 and the second electrode 416 of the active part 413A, the piezoelectric layer 415 vibrates, and accordingly the vibration plate 412 vibrates to generate ultrasonic waves.

[0080] When receiving ultrasonic waves, a common bias signal is input from the circuit board 23 to the second electrode terminal 416P. Then, when ultrasonic waves from an object are input to the piezoelectric actuator 22 and the vibration plate 412 vibrates, the piezoelectric element 413 flexes, and a potential difference is generated between the first electrode 414 and the second electrode 416 according to the flexure of the piezoelectric element 413. Thereby, a detection signal corresponding to the ultrasonic waves from the object is output from the first electrode terminal 414P to the circuit board 23.

[0081] Here, by comparing this embodiment and the comparative example, the influence of the width W1 of the first vertical wall 418 and the width W2 of the second vertical wall 419 on the piezoelectric actuator 22 is described.

[0082] First, refer to Figure 8 and Figure 9 to describe the piezoelectric actuator 22a of the comparative example.

[0083] As Figure 8 and Figure 9 shown, in the piezoelectric actuator 22a of the comparative example, the width W1 of the first vertical wall 418a is substantially equal to the width W2 of the second vertical wall 419a.

[0084] Next, refer to Figure 10 and Figure 11 to describe the respective frequency spectra of the piezoelectric actuator 22a of the comparative example and the piezoelectric actuator 22 of this embodiment. It should be noted that the frequency spectrum indicates what intensities and frequencies of vibration are included in the vibration being measured.

[0085] As Figure 10As shown, the frequency spectrum of the piezoelectric actuator 22a of the comparative example has a high intensity at the desired frequency, i.e., 8 to 9 MHz, but a narrow frequency band. In addition, the vibration of unnecessary frequencies outside the desired frequency, for example, the intensity at 3 to 4 MHz is also high. This is because the width W1 of the first vertical wall 418a of the piezoelectric actuator 22a is substantially equal to the width W2 of the second vertical wall 419a, and thus the first vertical wall 418 and the second vertical wall 419 have substantially the same resonance frequency. Therefore, when the vibration of the vibration plate 412 is transmitted to the first vertical wall 418 and the second vertical wall 419, the vibrations of the first vertical wall 418 and the second vertical wall 419 are easily combined and the resonance intensity becomes larger.

[0086] It should be noted that the vibration of unnecessary frequencies caused by the resonance of the first vertical wall 418a and the second vertical wall 419a easily occurs when there is water or a substance with a Young's modulus of several to several tens of MPa, such as silicone resin, between the first vertical wall 418a and the second vertical wall 419a, that is, in the opening 411A.

[0087] In contrast, as Figure 11 shown, the frequency spectrum of the piezoelectric actuator 22 of the present embodiment has a high intensity and a wide frequency band at the desired frequency, i.e., 3 to 7 MHz. In addition, the vibration intensity of unnecessary frequencies outside the desired frequency becomes lower.

[0088] As described above, in the present embodiment, the width W1 of the first vertical wall 418 and the width W2 of the second vertical wall 419 are different, and thus the first vertical wall 418 and the second vertical wall 419 have different resonance frequencies. Therefore, when the vibration of the vibration plate 412 is transmitted to the first vertical wall 418 and the second vertical wall 419, the vibrations of the first vertical wall 418 and the second vertical wall 419 are less likely to be combined, and the resonance intensities of the first vertical wall 418 and the second vertical wall 419 become smaller respectively. As a result, the occurrence of unnecessary frequency vibrations caused by the resonance of the first vertical wall 418 and the second vertical wall 419 can be suppressed.

[0089] As described above, according to the present embodiment, the following effects can be obtained.

[0090] The piezoelectric actuator 22 includes: a substrate 411 formed with an opening 411A; a diaphragm 412 having a first surface 412h that closes the opening 411A and a second surface 412r provided with a plurality of piezoelectric elements 413; a suppression portion 43 that suppresses the vibration of the diaphragm 412; a first vertical wall 418 extending from the first surface 412h toward the opening 411A; and a second vertical wall 419 extending from a position different from the first vertical wall 418 on the first surface 412h toward the opening 411A. Moreover, when the overlapping portion of the first electrode 414, the piezoelectric layer 415, and the second electrode 416 is defined as the active portion 413A of the piezoelectric element 413, when viewed from above in the stacking direction (Z direction) of the first electrode 414, the piezoelectric layer 415, and the second electrode 416, the first vertical wall 418 and the second vertical wall 419 are arranged to sandwich the active portion 413A. Since the width W2 of the second vertical wall 419 is different from the width W1 of the first vertical wall 418, the first vertical wall 418 and the second vertical wall 419 have different resonance frequencies, and the occurrence of vibration at unnecessary frequencies can be suppressed. Thus, a piezoelectric actuator 22 with high precision can be obtained.

[0091] In addition, even when there is water, silicone resin, etc. between the first vertical wall 418 and the second vertical wall 419, the occurrence of vibration at unnecessary frequencies caused by the resonance of the first vertical wall 418 and the second vertical wall 419 can be suppressed.

[0092] In addition, even when the vibration of the diaphragm 412 is transmitted to the first vertical wall 418 and the second vertical wall 419 and the first vertical wall 418 and the second vertical wall 419 vibrate, the piezoelectric element 413 surrounded by the suppression portion 43, the first vertical wall 418, and the second vertical wall 419 can be treated as an isolated oscillator, so that a piezoelectric actuator 22 with uniform frequency characteristics can be obtained.

[0093] In addition, since the leakage of the vibration energy of the diaphragm 412 can be suppressed by the first vertical wall 418 and the second vertical wall 419, the Q value of the piezoelectric element 413 can be increased, and a piezoelectric actuator 22 with excellent vibration stability can be obtained.

[0094] 2. Embodiment 2

[0095] Next, with reference to Figure 12 and Figure 13 the piezoelectric actuator 22b according to Embodiment 2 will be described. In the following description, the differences from the above-described Embodiment 1 will be mainly described, and the same structural components as those in Embodiment 1 will be denoted by the same reference numerals and repeated descriptions will be omitted.

[0096] As shown in Figure 13As shown, in the piezoelectric actuator 22b according to this embodiment, the height H1 of the first vertical wall 418b is different from the height H2 of the second vertical wall 419b. Specifically, the height H1 of the first vertical wall 418b is higher than the height H2 of the second vertical wall 419b.

[0097] As Figure 12 and Figure 13 shown, in the piezoelectric actuator 22b, the width W1 of the first vertical wall 418b is substantially equal to the width W2 of the second vertical wall 419b. In addition, the length L1 of the first vertical wall 418b is substantially equal to the length L2 of the second vertical wall 419b. In addition, the physical properties of the first vertical wall 418b are substantially equal to the physical properties of the second vertical wall 419b.

[0098] According to this embodiment, the same effects as those of Embodiment 1 can be obtained. Since the height H2 of the second vertical wall 419b is different from the height H1 of the first vertical wall 418b, the first vertical wall 418b and the second vertical wall 419b have different resonance frequencies respectively. As a result, when the vibration of the vibration plate 412 is transmitted to the first vertical wall 418b and the second vertical wall 419b, the resonance intensities of the first vertical wall 418b and the second vertical wall 419b become smaller respectively, so that the occurrence of unnecessary frequency vibrations caused by the resonance of the first vertical wall 418b and the second vertical wall 419b can be suppressed.

[0099] 3. Embodiment 3

[0100] Next, with reference to Figure 14 the piezoelectric actuator 22c according to Embodiment 3 will be described. In addition, in the following description, the differences from the above Embodiment 1 will be mainly described, and the same reference numerals will be given to the same structures as those in Embodiment 1 and the repeated descriptions will be omitted.

[0101] As Figure 14 shown, in the piezoelectric actuator 22c according to this embodiment, the length L1 of the first vertical wall 418c is different from the lengths L2a and L2b of the second vertical walls 419c and 420c. Specifically, the length L1 of the first vertical wall 418c is greater than the lengths L2a and L2b of the second vertical walls 419c and 420c.

[0102] As Figure 14 shown, when viewed from the Z direction in plan, the second vertical wall 419c and the second vertical wall 420c extend in parallel with the X direction and are arranged side by side in the X direction.

[0103] The second vertical wall 419c is formed to span a predetermined number of suppression portions 43 from the peripheral edge on the negative X-direction side of the opening portion 411A toward the positive X-direction side. The end portion on the negative X-direction side of the second vertical wall 419c is connected to the peripheral edge on the negative X-direction side of the opening portion 411A, and the end portion on the positive X-direction side of the second vertical wall 419c is arranged to face the end portion on the negative X-direction side of the second vertical wall 420c with a gap therebetween.

[0104] The second vertical wall 420c is formed to span a predetermined number of suppression portions 43 from the peripheral edge on the positive X-direction side of the opening portion 411A toward the negative X-direction side. The end portion on the positive X-direction side of the second vertical wall 420c is connected to the peripheral edge on the positive X-direction side of the opening portion 411A, and the end portion on the negative X-direction side of the second vertical wall 420c is arranged to face the end portion on the positive X-direction side of the second vertical wall 419c with a gap therebetween.

[0105] The distances from the respective end portions on the positive X-direction sides to the end portions on the negative X-direction sides of the second vertical walls 419c and 420c are the lengths L2a and L2b of the second vertical walls 419c and 420c, respectively. In the present embodiment, the length L2a of the second vertical wall 419c is substantially equal to the length L2b of the second vertical wall 420c, but the length L2a may also be different from the length L2b.

[0106] The width of the second vertical wall 419c is substantially equal to the width of the second vertical wall 420c, and is the width W2. In addition, although not shown, the height of the second vertical wall 419c is substantially equal to the height of the second vertical wall 420c, and is the height H2.

[0107] The width W1 of the first vertical wall 418c is substantially equal to the width W2 of the second vertical walls 419c and 420c. In addition, the height H1 of the first vertical wall 418c is substantially equal to the height H2 of the second vertical walls 419c and 420c. In addition, the physical properties of the first vertical wall 418c are substantially equal to the physical properties of the second vertical walls 419c and 420c.

[0108] According to the present embodiment, the same effects as those of Embodiment 1 can be obtained. Since the lengths L2a and L2b of the second vertical walls 419c and 420c are different from the length L1 of the first vertical wall 418c, the first vertical wall 418c and the second vertical walls 419c and 420c have different resonance frequencies, respectively. As a result, when the vibration of the diaphragm 412 is transmitted to the first vertical wall 418c and the second vertical walls 419c and 420c, the resonance intensities of the first vertical wall 418c and the second vertical walls 419c and 420c become smaller, respectively, and thus the occurrence of unnecessary frequency vibrations caused by the resonance of the first vertical wall 418c and the second vertical walls 419c and 420c can be suppressed.

[0109] 4. Embodiment 4

[0110] Next, refer toFigure 15 The piezoelectric actuator 22d according to Embodiment 4 will be described. In the following description, the differences from Embodiment 1 above will be mainly described, and the same reference numerals will be assigned to the same structures as those in Embodiment 1, and repeated descriptions will be omitted.

[0111] The physical properties of the first vertical wall 418d of the piezoelectric actuator 22d according to the present embodiment are different from those of the second vertical wall 419d. In the present embodiment, by making the materials forming the first vertical wall 418d and the second vertical wall 419d the same as each other, the physical properties of the first vertical wall 418d are made different from those of the second vertical wall 419d. For example, by making the first vertical wall 418d of silicon and the second vertical wall 419d of a resin material such as acrylic resin or epoxy resin, the Young's modulus of the first vertical wall 418d can be made different from that of the second vertical wall 419d.

[0112] As Figure 15 shown, the width W1 of the first vertical wall 418d is substantially equal to the width W2 of the second vertical wall 419d. The length L1 of the first vertical wall 418d and the length L2 of the second vertical wall 419d are substantially equal. In addition, although not shown, the height H1 of the first vertical wall 418d is substantially equal to the height H2 of the second vertical wall 419d.

[0113] In the present embodiment, the first vertical wall 418d can be formed by patterning the substrate 411 using a photolithography technique. The second vertical wall 419d can be formed by coating a photosensitive resin material on the diaphragm 412 by spin coating, sputtering, etc., and then patterning it using a photolithography technique.

[0114] According to the present embodiment, the same effects as those of Embodiment 1 can be obtained. Since the Young's modulus of the second vertical wall 419d is different from that of the first vertical wall 418d, the first vertical wall 418d and the second vertical wall 419d have different resonance frequencies, respectively. As a result, when the vibration of the diaphragm 412 is transmitted to the first vertical wall 418d and the second vertical wall 419d, the resonance intensities of the first vertical wall 418d and the second vertical wall 419d become smaller, respectively, and thus the occurrence of unnecessary frequency vibrations caused by the resonance of the first vertical wall 418d and the second vertical wall 419d can be suppressed.

[0115] It should be noted that in the present embodiment, as an example of the physical properties of the first vertical wall 418d and the second vertical wall 419d, the Young's modulus as the elastic modulus is shown, but physical properties other than the Young's modulus, such as the rigidity modulus and the internal loss, may also be used.

[0116] As described above, the widths W1 and W2 of the first vertical wall 418 and the second vertical wall 419 in Embodiment 1 are different, the heights H1 and H2 of the first vertical wall 418b and the second vertical wall 419b in Embodiment 2 are different, the length L1 of the first vertical wall 418c in Embodiment 3 is different from the lengths L2a and L2b of the second vertical walls 419c and 420c, and the physical properties of the first vertical wall 418c and the second vertical wall 419c in Embodiment 4 are different. Thus, in Embodiments 1 to 4, the second vertical wall is different from the first vertical wall in one aspect among width, height, length, and physical properties, but may also be different from the first vertical wall in two or more aspects among width, height, length, and physical properties. In other words, by making the second vertical wall different from the first vertical wall in at least one aspect among width, height, length, and physical properties, the same effect as in Embodiment 1 can be obtained.

[0117] 5. Embodiment 5

[0118] Next, with reference to Figure 16 the piezoelectric actuator 22e according to Embodiment 5 will be described. In addition, in the following description, the differences from the above-described Embodiment 1 will be mainly described, and the same reference numerals will be given to the same structures as in Embodiment 1, and the repeated description will be omitted.

[0119] The piezoelectric actuator 22e according to the present embodiment is an example of an embodiment in which two or more of the width, height, length, and physical properties of the first vertical wall and the second vertical wall are different, and the widths W1 and W2 and the physical properties of the first vertical wall 418e and the second vertical wall 419e are different.

[0120] As Figure 16 shown, in the piezoelectric actuator 22e, the width W1 of the first vertical wall 418e is different from the width W2 of the second vertical wall 419e.

[0121] In addition, in the present embodiment, the first vertical wall 418e is made of silicon, and the second vertical wall 419e is made of a resin material, whereby the Young's modulus of the first vertical wall 418e is different from the Young's modulus of the second vertical wall 419e.

[0122] The length L1 of the first vertical wall 418e is substantially equal to the length L2 of the second vertical wall 419e. In addition, although not shown, the height H1 of the first vertical wall 418e is substantially equal to the height H2 of the second vertical wall 419e.

[0123] According to this embodiment, the same effects as those of Embodiment 1 can be obtained. Since the width W2 and Young's modulus of the second vertical wall 419e are different from the width W1 and Young's modulus of the first vertical wall 418e, the first vertical wall 418e and the second vertical wall 419e have different resonance frequencies respectively. As a result, when the vibration of the diaphragm 412 is transmitted to the first vertical wall 418e and the second vertical wall 419e, the resonance intensities of the first vertical wall 418e and the second vertical wall 419e become smaller respectively, thereby suppressing the occurrence of unnecessary frequency vibrations caused by the resonance of the first vertical wall 418e and the second vertical wall 419e.

[0124] 6. Embodiment 6

[0125] Next, with reference to Figure 17 and Figure 18 the piezoelectric actuator 22f according to Embodiment 6 will be described. In addition, in the following description, the differences from Embodiment 1 above will be mainly described, and the same reference numerals will be given to the same structures as those in Embodiment 1 and the repeated descriptions will be omitted.

[0126] The piezoelectric actuator 22f according to this embodiment is an example of an embodiment in which two or more of the width, height, length, and physical properties of the first vertical wall and the second vertical wall are different, and the heights, lengths, and physical properties of the first vertical wall 418f and the second vertical walls 419f and 420f are different from each other.

[0127] As Figure 17 shown, when viewed from above in the Z direction, the second vertical wall 419f and the second vertical wall 420f extend in parallel with the X direction and are arranged side by side in the X direction. The end portion on the negative X side of the second vertical wall 419f is connected to the peripheral edge on the negative X side of the opening 411A, the end portion on the positive X side of the second vertical wall 420f is connected to the peripheral edge on the positive X side of the opening 411A, and the end portion on the positive X side of the second vertical wall 419f and the end portion on the negative X side of the second vertical wall 420f are arranged to face each other with a gap therebetween.

[0128] The width of the second vertical wall 419f is substantially equal to the width of the second vertical wall 420f and is the width W2. The width W2 of the second vertical walls 419f and 420f is substantially equal to the width W1 of the first vertical wall 418f.

[0129] Although not shown, the height of the second vertical wall 419f is substantially equal to the height of the second vertical wall 420f and is the height H2.

[0130] As Figure 18 shown, the height H1 of the first vertical wall 418f is different from the height H2 of the second vertical walls 419f and 420f. Specifically, the height H1 of the first vertical wall 418f is higher than the height H2 of the second vertical walls 419f and 420f.

[0131] As Figure 17 shown, the distances of the second vertical walls 419f and 420f from the end on the positive X-direction side to the end on the negative X-direction side are the lengths L2a and L2b of the second vertical walls 419f and 420f, respectively.

[0132] The length L1 of the first vertical wall 418f is different from the lengths L2a and L2b of the second vertical walls 419f and 420f. Specifically, the length L1 of the first vertical wall 418f is greater than the lengths L2a and L2b of the second vertical walls 419f and 420f.

[0133] In addition, in the present embodiment, the first vertical wall 418f is made of silicon, the second vertical walls 419f and 420f are made of a resin material, and the Young's modulus of the first vertical wall 418f is different from the Young's moduli of the second vertical walls 419f and 420f.

[0134] According to the present embodiment, the same effects as those of Embodiment 1 can be obtained. The heights H2, lengths L2a and L2b of the second vertical walls 419f and 420f, and the Young's modulus as an example of physical properties are different from the height H1, length L1, and Young's modulus of the first vertical wall 418f. Therefore, the first vertical wall 418f, the second vertical walls 419f and 420f have different resonance frequencies. As a result, when the vibration of the diaphragm 412 is transmitted to the first vertical wall 418f, the second vertical walls 419f and 420f, the resonance intensities of the first vertical wall 418f and the second vertical walls 419f and 420f are reduced respectively, thereby suppressing the occurrence of unnecessary frequency vibrations caused by the resonance of the first vertical wall 418f, the second vertical walls 419f and 420f.

[0135] 7. Embodiment 7

[0136] Next, with reference to Figures 19 to 21 the piezoelectric actuator 22g according to Embodiment 7 will be described. In addition, in the following description, the differences from Embodiment 1 described above will be mainly described, and the same reference numerals will be given to the same structures as those in Embodiment 1 and the repeated descriptions will be omitted.

[0137] The piezoelectric actuator 22g according to the present embodiment is different from the piezoelectric actuator 22 of Embodiment 1 in that it has a plurality of suppression portions 43A extending in parallel with the Y direction and a plurality of suppression portions 43B extending in parallel with the X direction when viewed from above in the Z direction.

[0138] As Figure 19 and Figure 20 shown, the suppression portions 43A and 43B are provided corresponding to the active portions 413A.

[0139] When viewed from above in the Z direction, the suppression portions 43A extend parallel to the Y direction. A plurality of suppression portions 43A are arranged side by side in the X direction. A plurality of piezoelectric elements 413 arranged side by side in the Y direction are disposed between the plurality of suppression portions 43A. In other words, the suppression portions 43A are arranged to sandwich the active portion 413A in the X direction when viewed from above in the Z direction.

[0140] When viewed from above in the Z direction, the suppression portions 43B extend parallel to the X direction. A plurality of suppression portions 43B are arranged side by side in the Y direction. A plurality of piezoelectric elements 413 arranged side by side in the X direction are disposed between the plurality of suppression portions 43B. In other words, the suppression portions 43B are arranged to sandwich the active portion 413A in the Y direction when viewed from above in the Z direction.

[0141] That is, on the positive side and the negative side of the X direction of the active portion 413A, the suppression portions 43A are disposed on the diaphragm 412, and on the positive side and the negative side of the Y direction of the active portion 413A, the suppression portions 43B are disposed on the diaphragm 412. Thereby, the vibration ranges of the diaphragm 412 in the X direction and the Y direction can be restricted by the suppression portions 43A and the suppression portions 43B.

[0142] As Figure 19 shown, the length L1 of the first vertical wall 418g is substantially equal to the length L2 of the second vertical wall 419g. As Figure 21 shown, the height H1 of the first vertical wall 418g is substantially equal to the height H2 of the second vertical wall 419g. As Figure 19 and Figure 21 shown, the width W1 of the first vertical wall 418g is different from the width W2 of the second vertical wall 419g. Specifically, the width W1 of the first vertical wall 418g is greater than the width W2 of the second vertical wall 419g.

[0143] According to the present embodiment, the same effects as those of the first embodiment can be obtained. Since the width W2 of the second vertical wall 419g is different from the width W1 of the first vertical wall 418g, the first vertical wall 418g and the second vertical wall 419g have different resonance frequencies. As a result, when the vibration of the diaphragm 412 is transmitted to the first vertical wall 418g and the second vertical wall 419g, the resonance intensities of the first vertical wall 418g and the second vertical wall 419g become smaller respectively, so that the occurrence of unnecessary frequency vibrations caused by the resonance of the first vertical wall 418g and the second vertical wall 419g can be suppressed.

[0144] 8. Embodiment 8

[0145] Next, referring to Figure 22 and Figure 23The piezoelectric actuator 22h according to Embodiment 8 will be described. In addition, in the following description, the differences from Embodiment 7 described above will be mainly described, and the same reference numerals will be given to the same structures as those in Embodiment 7, and repeated descriptions will be omitted.

[0146] As Figure 23 shown, the height H1 of the first vertical wall 418h of the piezoelectric actuator 22h according to this embodiment is different from the height H2 of the second vertical wall 419h. Specifically, the height H1 of the first vertical wall 418h is higher than the height H2 of the second vertical wall 419h.

[0147] As Figure 22 shown, in this embodiment, the width W1 of the first vertical wall 418h is substantially equal to the width W2 of the second vertical wall 419h, and the length L1 of the first vertical wall 418h is substantially equal to the length L2 of the second vertical wall 419h.

[0148] According to this embodiment, the same effect as that of Embodiment 1 can be obtained. Since the height H2 of the second vertical wall 419h is different from the height H1 of the first vertical wall 418h, the first vertical wall 418h and the second vertical wall 419h have different resonance frequencies respectively. As a result, when the vibration of the vibration plate 412 is transmitted to the first vertical wall 418h and the second vertical wall 419h, the resonance intensities of the first vertical wall 418h and the second vertical wall 419h become smaller respectively, so that the occurrence of unnecessary frequency vibrations caused by the resonance of the first vertical wall 418h and the second vertical wall 419h can be suppressed.

[0149] 9. Embodiment 9

[0150] Next, with reference to Figure 24 the piezoelectric actuator 22k according to Embodiment 9 will be described. In addition, in the following description, the differences from Embodiment 7 described above will be mainly described, and the same reference numerals will be given to the same structures as those in Embodiment 7, and repeated descriptions will be omitted.

[0151] As Figure 24 shown, the length L1 of the first vertical wall 418k of the piezoelectric actuator 22k according to this embodiment is different from the lengths L2a and L2b of the second vertical walls 419k and 420k. Specifically, the length L1 of the first vertical wall 418k is greater than the lengths L2a and L2b of the second vertical walls 419k and 420k.

[0152] As Figure 24As shown, when viewed from above in the Z direction, the second vertical wall 419k and the second vertical wall 420k extend parallel to the X direction and are arranged side by side in the X direction. The end portion on the negative X side of the second vertical wall 419k is connected to the peripheral edge on the negative X side of the opening 411A, the end portion on the positive X side of the second vertical wall 420k is connected to the peripheral edge on the positive X side of the opening 411A, and the end portion on the positive X side of the second vertical wall 419k and the end portion on the negative X side of the second vertical wall 420k are arranged to face each other with a gap therebetween.

[0153] The distances from the end portions on the positive X side to the end portions on the negative X side of the second vertical walls 419k and 420k are the lengths L2a and L2b of the second vertical walls 419k and 420k, respectively.

[0154] The width of the second vertical wall 419k is substantially equal to the width of the second vertical wall 420k and is width W2. The width W2 of the second vertical walls 419k and 420k is substantially equal to the width W1 of the first vertical wall 418k. Additionally, although not shown, the height of the second vertical wall 419k is substantially equal to the height of the second vertical wall 420k and is height H2. The height H2 of the second vertical walls 419k and 420k is substantially equal to the height H1 of the first vertical wall 418k.

[0155] According to the present embodiment, the same effects as those of Embodiment 1 can be obtained. Since the lengths L2a and L2b of the second vertical walls 419k and 420k are different from the length L1 of the first vertical wall 418k, the first vertical wall 418k and the second vertical walls 419k and 420k have different resonance frequencies. As a result, when the vibration of the diaphragm 412 is transmitted to the first vertical wall 418k and the second vertical walls 419k and 420k, the resonance intensities of the first vertical wall 418k and the second vertical walls 419k and 420k become smaller, respectively, thereby suppressing the occurrence of unnecessary frequency vibrations caused by the resonance of the first vertical wall 418k and the second vertical walls 419k and 420k.

[0156] 10. Embodiment 10

[0157] Next, refer to Figure 25 The piezoelectric actuator 22m according to Embodiment 10 will be described. In addition, in the following description, the differences from the above-described Embodiment 7 will be mainly described, and the same reference numerals will be given to the same structures as those in Embodiment 7 and the repeated descriptions will be omitted.

[0158] The physical properties of the first vertical wall 418m of the piezoelectric actuator 22m according to the present embodiment are different from the physical properties of the second vertical wall 419m. In the present embodiment, the first vertical wall 418m is made of silicon and the second vertical wall 419m is made of a resin material, whereby the Young's modulus of the first vertical wall 418m is different from the Young's modulus of the second vertical wall 419m.

[0159] As Figure 25 shown, the width W1 of the first vertical wall 418m is substantially equal to the width W2 of the second vertical wall 419m. The length L1 of the first vertical wall 418m is substantially equal to the length L2 of the second vertical wall 419m. Additionally, although not shown, the height H1 of the first vertical wall 418m is substantially equal to the height H2 of the second vertical wall 419m.

[0160] According to the present embodiment, the same effects as those of Embodiment 1 can be obtained. Since the Young's modulus of the second vertical wall 419m is different from that of the first vertical wall 418m, the first vertical wall 418m and the second vertical wall 419m have different resonance frequencies, respectively. As a result, when the vibration of the vibrating plate 412 is transmitted to the first vertical wall 418m and the second vertical wall 419m, the resonance intensities of the first vertical wall 418m and the second vertical wall 419m become smaller respectively, thereby suppressing the occurrence of unnecessary frequency vibrations caused by the resonance of the first vertical wall 418m and the second vertical wall 419m.

Claims

1. A piezoelectric actuator, characterized in that, Comprising: A substrate having an opening formed therein; A diaphragm disposed on the substrate so as to block the opening with a first surface; A piezoelectric element disposed corresponding to the opening on a second surface of the diaphragm opposite to the first surface; A suppression portion for suppressing vibration of the diaphragm; A first vertical wall extending from the first surface toward the opening; And A second vertical wall extending from a position different from the first vertical wall on the first surface toward the opening, The piezoelectric element is laminated with a first electrode, a piezoelectric layer, and a second electrode in this order from the second surface side. When a portion where the first electrode, the piezoelectric layer, and the second electrode are overlapped is an active portion, when viewed from above in the lamination direction, the first vertical wall and the second vertical wall are arranged to sandwich the active portion, At least one of the width, the length, and the physical properties of the second vertical wall when viewed from above in the lamination direction is different from those of the first vertical wall.

2. The piezoelectric actuator according to claim 1, wherein The suppression portion is provided on the second surface of the diaphragm.

3. An ultrasonic component, characterized in that, Comprising: The piezoelectric actuator according to claim 1 or 2; A transmission circuit for transmitting ultrasonic waves to the piezoelectric actuator; And A reception circuit for receiving ultrasonic waves from the piezoelectric actuator.

4. An ultrasonic probe, characterized in that, Comprising: The ultrasonic element according to claim 3; and A housing for accommodating the ultrasonic element.

5. An ultrasonic device, characterized in that, Comprising: The ultrasonic element according to claim 3; and A control portion for controlling the ultrasonic element.

6. An electronic device, characterized in that, Comprising: The piezoelectric actuator according to claim 1 or 2.

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