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

Abstract

To provide a piezoelectric actuator, an ultrasonic element, an ultrasonic probe, an ultrasonic apparatus, and an electronic device that can prevent the appearance of vibrations with an unnecessary frequency.SOLUTION: A piezoelectric actuator 22 comprises: a diaphragm 412 having a first surface 412h that closes an opening 411A provided in a substrate 411, and a second surface 412r that is provided with a plurality of piezoelectric elements 413; a prevention unit 43 that prevents vibration of the diaphragm 412; and a plurality of standing walls 418 that extend from the first surface 412h to the opening 411A. When a portion in which a first electrode 414, a piezoelectric layer 415, and a second electrode 416 overlap each other is an active part 413A of the piezoelectric element 413, in plan view from a stacking direction of the first electrode 414, piezoelectric layer 415, and second electrode 416, the standing wall 418 is provided between the adjacent active parts 413A, and in a plane orthogonal to the stacking direction, the distance W1 between the adjacent standing walls 418 is longer than the distance W2 between the adjacent active parts 413A.SELECTED DRAWING: Figure 6

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 technology]

[0002] Conventionally, as shown in Patent Document 1, an ultrasonic sensor has been known which includes a substrate having an opening formed therein, a diaphragm provided on the substrate so as to cover the opening, and a plurality of piezoelectric elements including a first electrode, a piezoelectric layer, and a second electrode stacked on the opposite side of the opening of the diaphragm, in which a portion where the first electrode, the piezoelectric layer, and the second electrode completely overlap in the direction in which the first electrode, the piezoelectric layer, and the second electrode are stacked is defined as an active portion, and a suppression portion is provided between adjacent active portions to suppress vibration of the diaphragm. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-188208 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above configuration, the size of the opening can be made larger relative to the active part. However, if the size of the opening is made larger, the diaphragm and the like can be directly contacted from the outside, which may lead to a malfunction. By providing a beam in the opening, the diaphragm and the like can be protected from the outside, but there is a problem in that the vibration of the diaphragm is transmitted to the beam, and the beam vibrates, resulting in the appearance of vibrations of unnecessary frequencies. [Means for solving the problem]

[0005] The piezoelectric actuator comprises a substrate having an opening formed therein, a vibration plate provided on the substrate and having a first surface closing the opening, a plurality of piezoelectric elements provided on a second surface of the vibration plate opposite the first surface, the plurality of piezoelectric elements being arranged to correspond to the openings, a suppression section being arranged to correspond to the piezoelectric elements and suppressing vibration of the vibration plate, and a plurality of standing walls extending from the first surface to the opening, the piezoelectric elements being stacked in the order of a first electrode, a piezoelectric layer, and a second electrode from the second surface side, and when a portion where the first electrode, the piezoelectric layer, and the second electrode overlap is defined as an active section, in a plan view from the stacking direction, the standing walls are provided between adjacent active sections, and in a plane perpendicular to the stacking direction, the distance between adjacent standing walls is longer than the distance between adjacent active sections.

[0006] The ultrasonic element includes the piezoelectric actuator described above, a transmitting circuit for the piezoelectric actuator to transmit ultrasonic waves, and a receiving circuit for the piezoelectric actuator to receive ultrasonic waves.

[0007] The ultrasonic probe includes the ultrasonic element described above and a housing that houses the ultrasonic element.

[0008] The ultrasonic device includes the ultrasonic element described above and a control unit that controls the ultrasonic element.

[0009] The electronic device comprises the piezoelectric actuator described above. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a perspective view showing a schematic configuration of an ultrasonic measurement device according to a first embodiment. [Diagram 2] FIG. 1 is a block diagram showing a schematic configuration of an ultrasonic measurement device according to a first embodiment. [Diagram 3] FIG. 1 is a perspective view showing a schematic configuration of a piezoelectric actuator according to a first embodiment. [Figure 4] FIG. 2 is a plan view of the piezoelectric actuator according to the first embodiment, as viewed from the base side. [Diagram 5]FIG. 2 is a plan view of the piezoelectric actuator according to the first embodiment, as viewed from the sealing plate side. [Figure 6] 5 is a cross-sectional view taken along line AA in FIG. 4. [Figure 7] FIG. 11 is a plan view of a piezoelectric actuator according to a comparative example, as viewed from the base side. [Figure 8] FIG. 13 is a diagram showing a frequency spectrum of a piezoelectric actuator according to a comparative example. [Figure 9] FIG. 4 is a diagram showing a frequency spectrum of the piezoelectric actuator according to the first embodiment. [Figure 10] FIG. 11 is a plan view of a piezoelectric actuator according to a second embodiment, as viewed from the base side. [Figure 11] 11 is a cross-sectional view taken along line BB in FIG. 10 . DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] 1. Embodiment 1 An ultrasonic measurement device 1 according to a first embodiment will be described with reference to FIGS. As shown in FIGS. 1 and 2, an ultrasonic measurement device 1 as an ultrasonic device and an electronic device of this embodiment has an ultrasonic probe 2 and a control unit 10 electrically connected to the ultrasonic probe 2 via a cable 3.

[0012] The ultrasonic measurement device 1 contacts an ultrasonic probe 2 with the surface of a living body such as a human body, transmits ultrasonic waves from the ultrasonic probe 2, and receives ultrasonic waves reflected within the living body by the ultrasonic probe 2. Based on the received signal, it is possible to obtain internal tomographic images of the living body and to measure the condition of organs within the living body, such as blood flow.

[0013] The ultrasonic probe 2 has an ultrasonic element 24 and a housing 21 that houses the ultrasonic element 24.

[0014] The ultrasonic element 24 includes a piezoelectric actuator 22 and a circuit board 23 that controls the piezoelectric actuator 22 .

[0015] The circuit board 23 has a transmission circuit 232 for transmitting ultrasonic waves from the piezoelectric actuator 22, a reception circuit 233 for the piezoelectric actuator 22 to receive ultrasonic waves and output a reception signal, and a selection circuit 231.

[0016] The selection circuit 231 switches between a transmission connection that connects the piezoelectric actuator 22 to a transmission circuit 232 and a reception connection that connects the piezoelectric actuator 22 to a reception circuit 233 under the control of the control unit 10 .

[0017] When switched to the transmission connection, the transmission circuit 232 outputs a transmission signal via the selection circuit 231 to the piezoelectric actuator 22 to transmit an ultrasonic wave.

[0018] When switched to the receiving connection, the receiving circuit 233 outputs the receiving signal input from the piezoelectric actuator 22 via the selection circuit 231 to the control unit 10. The receiving circuit 233 performs various signal processing such as converting the receiving signal into a digital signal, removing noise components, amplifying the signal to a desired signal level, and so on, and then outputs the processed receiving signal to the control unit 10.

[0019] The housing 21 is formed, for example, in a rectangular box shape. One surface of the housing 21 serves as a 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. A passage 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 passage hole 21C.

[0020] The control unit 10 has an operation unit 11, a display unit 12, a storage unit 13, and a calculation unit 14. The control unit 10 controls the ultrasonic element 24. The control unit 10 can use, for example, a general-purpose terminal device such as a smartphone or a personal computer, or a dedicated terminal device for operating the ultrasonic probe 2.

[0021] The operation unit 11 is a user interface for operating the ultrasonic measurement device 1, and may be, for example, a touch panel or operation buttons provided on the display unit 12. The display unit 12 is, for example, configured with a liquid crystal display or the like, and displays images. The storage unit 13 stores various programs and various data for controlling the ultrasonic measurement device 1. The calculation unit 14 is, for example, configured with a calculation circuit such as a CPU, and a storage circuit such as a memory. The calculation unit 14 reads and executes various programs stored in the storage unit 13, thereby controlling the generation and output processing of a transmission signal for the transmission circuit 232, and controlling the frequency setting, gain setting, etc. of a reception signal for the reception circuit 233.

[0022] The piezoelectric actuator 22 according to the first embodiment will be described with reference to Fig. 3 to Fig. 6 and Fig. 9. Fig. 5 illustrates a state in which the sealing plate 42 has been removed for the sake of convenience in explaining the internal configuration of the piezoelectric actuator 22. In addition, for the sake of convenience in explaining the internal configuration of the piezoelectric actuator 22, the dimensional ratios of the components in the figures are different from the actual ratios.

[0023] In the coordinate system shown in the drawings, three mutually orthogonal axes are referred to as the X-axis, Y-axis, and Z-axis. The direction along the X-axis is referred to as the "X-direction", the direction along the Y-axis is referred to as the "Y-direction", and the direction along the Z-axis is referred to as the "Z-direction", with the arrows pointing in the positive direction. In addition, in a plan view from the Z-direction, the surface on the positive side of the Z-direction is referred to as the top surface, and the opposite surface on the negative side of the Z-direction is referred to as the bottom surface.

[0024] As shown in FIG. 3, the piezoelectric actuator 22 includes a base portion 41, a sealing plate 42, and a suppressing portion 43.

[0025] 3 and 4, the base 41 has a substrate 411 in which an opening 411A is formed, a vibration plate 412 closing the opening 411A, a plurality of piezoelectric elements 413 provided on the vibration plate 412, and a plurality of standing walls 418 provided on the vibration plate 412. Note that an acoustic matching layer, an acoustic lens, or the like may be provided in the opening 411A of the substrate 411.

[0026] The substrate 411 is a semiconductor substrate such as silicon. The substrate 411 has an opening 411A in the center of the substrate 411 in plan view from the Z direction. In this embodiment, the opening 411A has a rectangular shape in which the length of a side parallel to the Y direction is shorter than the length of a side parallel to the X direction in plan view from the Z direction.

[0027] The diaphragm 412 is a thin film made of, for example, silicon oxide or a laminate of silicon oxide and zirconium oxide. The diaphragm 412 has a first surface 412h and a second surface 412r 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 of the substrate 411 from the lower surface side of the substrate 411.

[0028] Standing wall 418 is provided on first surface 412h of diaphragm 412, and extends from first surface 412h to opening 411A. By providing standing wall 418, direct contact with diaphragm 412 from the outside through opening 411A can be prevented.

[0029] The standing wall 418 extends parallel to the Y direction in a plan view from the Z direction. The ends of the standing wall 418 on the positive side and the negative side in the Y direction are connected to the periphery of the opening 411A on the positive side and the negative side in the Y direction, respectively. This allows the standing wall 418 to function as a beam that supports the diaphragm 412, thereby improving the strength of the diaphragm 412.

[0030] In this embodiment, as described above, the opening 411A has a rectangular shape in which the length of the side parallel to the Y direction is shorter than the length of the side parallel to the X direction in a plan view from the Z direction, so that the length of the standing wall 418 is shorter when it extends parallel to the Y direction which is the short-side direction of the opening 411A than when it extends parallel to the X direction which is the long-side direction of the opening 411A. Therefore, by extending the standing wall 418 parallel to the Y direction, the strength of the standing wall 418 can be increased.

[0031] In this embodiment, the standing wall 418 is formed by patterning the substrate 411 using a photolithography technique, but this is not limiting, and the standing wall 418 may be formed of a resin material, for example, by applying a photosensitive resin material to the opening 411A by spin coating, sputtering, or the like, and then patterning the resin material using a photolithography technique.

[0032] The piezoelectric element 413 and the suppression section 43 are provided on the second surface 412r of the diaphragm 412.

[0033] The sealing plate 42 is formed in substantially the same shape as the substrate 411 in plan view from the Z direction. The sealing plate 42 is disposed opposite the second surface 412r of the vibration plate 412. The upper surface of the sealing plate 42 and the lower surface of the substrate 411 are joined via the vibration plate 412. The sealing plate 42 has a space S due to a recess that is recessed downward in the center of the upper surface in plan view from the Z direction, and the piezoelectric element 413 provided on the second surface 412r of the vibration plate 412 is sealed in this space S.

[0034] 4 to 6, the multiple piezoelectric elements 413 are provided on a second surface 412r opposite to the first surface 412h of the vibration plate 412, corresponding to the opening 411A of the substrate 411. Specifically, the piezoelectric elements 413 are arranged so as to overlap with the opening 411A in a plan view from the Z direction.

[0035] The piezoelectric element 413 is a laminated body in which a first electrode 414, a piezoelectric layer 415, and a second electrode 416 are laminated. The first electrode 414, the piezoelectric layer 415, and the second electrode 416 are laminated in this order from the second surface 412r side of the vibration plate 412. In a plan view from the Z direction, which is the lamination direction in which the first electrode 414, the piezoelectric layer 415, and the second electrode 416 are laminated, a portion where the first electrode 414, the piezoelectric layer 415, and the second electrode 416 overlap functions as an active section 413A.

[0036] The first electrode 414 extends in the Y direction and is provided continuously across the multiple active parts 413A. The ends of the multiple first electrodes 414 aligned in the X direction on the positive and negative Y sides are wired at the outer periphery of the substrate 411 on the positive and negative Y sides, respectively, and are electrically connected to first electrode terminals 414P provided on the outer periphery of the substrate 411 on the positive and negative Y sides in the Y direction.

[0037] The piezoelectric layers 415 are arranged in a matrix shape corresponding to the intersections of the first electrodes 414 and the second electrodes 416 when viewed from above in the Z direction. The piezoelectric layers 415 can typically use a lead zirconate titanate-based composite oxide with a perovskite structure. This makes it easier to ensure the amount of displacement of the piezoelectric elements 413. The piezoelectric layers 415 can also use a lead-free composite oxide with a perovskite structure. This allows the piezoelectric actuator 22 to be realized using a lead-free material that puts less strain on the environment.

[0038] The second electrode 416 extends in the X direction and is provided continuously across the multiple active parts 413A. The ends of the multiple second electrodes 416 arranged in the Y direction on the negative X side are connected to each other and drawn out to the outer periphery of the substrate 411 on the positive and negative Y sides in the Y direction. The second electrodes 416 drawn out to the outer periphery of the substrate 411 are electrically connected to second electrode terminals 416P provided on the outer periphery of the substrate 411 on the positive and negative Y sides in the Y direction.

[0039] There is no limitation on the material of the first electrode 414 and the second electrode 416 as long as they are conductive. For example, a conductive layer of iridium, platinum, titanium, or the like can be used as the material of the first electrode 414 and the second electrode 416. The conductive layer may be a single layer or multiple layers.

[0040] The multiple piezoelectric elements 413 are arranged in a matrix along a Y direction that is a first axis perpendicular to the Z direction that is a lamination direction in which the first electrode 414, the piezoelectric layer 415, and the second electrode 416 are laminated in the active part 413A, and an X direction that is a second axis perpendicular to the first axis, the Y axis. In this embodiment, one transmission / reception row is formed by the multiple piezoelectric elements 413 arranged in a row in the Y direction, one channel CH is formed by the multiple transmission / reception rows arranged in a row in the X direction, and a matrix of the multiple piezoelectric elements 413 is formed by the multiple channels CH arranged in a row in the X direction.

[0041] 5 and 6, the suppression section 43 is provided on the second surface 412r of the diaphragm 412. The upper surface of the suppression section 43 is joined to the second surface 412r of the diaphragm 412, and the lower surface of the suppression section 43 is joined to the sealing plate 42. In this manner, the suppression section 43 can fix the diaphragm 412 and suppress the vibration of the diaphragm 412.

[0042] The suppression section 43 is provided corresponding to the piezoelectric element 413. The suppression section 43 has a plurality of first suppression sections 43A formed to extend in the X direction and a plurality of second suppression sections 43B formed to extend in the Y direction. The first suppression sections 43A are arranged between the piezoelectric elements 413 adjacent to each other in the Y direction, and the second suppression sections 43B are arranged between the piezoelectric elements 413 adjacent to each other in the X direction. That is, the first suppression sections 43A are arranged on the vibration plate 412 on the positive side in the Y direction and the negative side in the Y direction of the piezoelectric element 413, and the second suppression sections 43B are arranged on the vibration plate 412 on the positive side in the X direction and the negative side in the X direction of the piezoelectric element 413. In this way, the suppression section 43 can limit the vibration range of the vibration plate 412 in the Y direction and the X direction.

[0043] The suppression portion 43 is made of, for example, a resin material, and can be formed by applying a photosensitive resin material to the diaphragm 412 by spin coating, sputtering, or the like, and then patterning the material using a photolithography technique.

[0044] In this embodiment, as described above, suppression unit 43 is provided on second surface 412r of diaphragm 412, but suppression unit 43 may be provided on first surface 412h of diaphragm 412. However, providing suppression unit 43 on second surface 412r of diaphragm 412 makes it easier to suppress vibration of diaphragm 412.

[0045] The sealing plate 42 has through holes (not shown) at positions corresponding to the first electrode terminal 414P and the second electrode terminal 416P in a plan view from the Z direction. A wiring member (not shown), such as an FPC (Flexible Printed Circuit), is inserted through the through holes (not shown). The first electrode terminal 414P and the second electrode terminal 416P are electrically connected to the circuit board 23 via the wiring member (not shown).

[0046] When transmitting ultrasonic waves, a drive signal is input to the first electrode terminal 414P and a common bias signal is input to the second electrode terminal 416P from the circuit board 23 via a wiring member (not shown). 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, causing the piezoelectric layer 415 to vibrate, which in turn causes the diaphragm 412 to vibrate and generate ultrasonic waves.

[0047] When ultrasonic waves are received, a common bias signal is input from the circuit board 23 to the second electrode terminal 416P. When ultrasonic waves from the object are input to the piezoelectric actuator 22 and the vibration plate 412 vibrates, the piezoelectric element 413 deflects, and a potential difference is generated between the first electrode 414 and the second electrode 416 in response to the deflection of the piezoelectric element 413. As a result, a detection signal corresponding to the ultrasonic waves from the object is output from the first electrode terminal 414P to the circuit board 23.

[0048] 4 and 6, a plurality of standing walls 418 extending from the first surface 412h to the opening 411A are provided on the first surface 412h of the diaphragm 412. The opening 411A is divided into a plurality of small openings by the standing walls 418. In other words, the standing walls 418 function as partitions surrounding the plurality of small openings.

[0049] The multiple standing walls 418 are provided between adjacent active parts 413A in a plan view from the Z direction, which is the lamination direction in which the first electrode 414, the piezoelectric layer 415, and the second electrode 416 are laminated in the active part 413A of the piezoelectric element 413. The multiple standing walls 418 extend parallel to the Y direction along the Y axis, which is a first axis perpendicular to the Z direction, and the multiple standing walls 418 extending parallel to the Y direction are arranged side by side in the X direction along the X axis, which is a second axis perpendicular to the Y axis, which is the first axis.

[0050] In this embodiment, the standing wall 418 extends parallel to the Y direction, but the standing wall 418 may extend parallel to the X direction.

[0051] 4 to 6, the standing walls 418 and the active parts 413A are arranged so that the distance W1 between adjacent standing walls 418 aligned in the X direction is longer than the distance W2 between adjacent active parts 413A of the piezoelectric elements 413 aligned in the X direction. In this way, by increasing the distance W1 between adjacent standing walls 418 aligned in the X direction, the bond between the standing walls 418 can be weakened, and therefore the appearance of vibrations of unnecessary frequencies can be suppressed.

[0052] In addition, the standing walls 418 and the suppression section 43 are arranged so that the distance W1 between the standing walls 418 adjacent to each other in the X direction is more than twice the distance W3 between the suppression sections 43 adjacent to each other in the X direction. The distance W3 between the suppression sections 43 adjacent to each other in the X direction indicates the width in the X direction of the vibration region in which the vibration plate 412 can vibrate due to the vibration of the active section 413A without being suppressed by the suppression section 43. In other words, by arranging the standing walls 418 and the suppression section 43 so that the distance W1 between the standing walls 418 adjacent to each other in the X direction is more than twice the distance W3 between the suppression sections 43 adjacent to each other in the X direction, two or more vibration regions in which the vibration plate 412 can vibrate without being suppressed by the suppression section 43 can be arranged in the X direction between the standing walls 418 adjacent to each other in the X direction. In this embodiment, two vibration regions in which the vibration plate 412 can vibrate without being suppressed by the suppression section 43 are arranged in the X direction between the standing walls 418 adjacent to each other in the X direction.

[0053] In this way, by making the distance W1 between adjacent vertical walls 418 lined up in the X direction at least twice the distance W3 between adjacent suppression sections 43 lined up in the X direction, the number of vertical walls 418 to which the vibration of the diaphragm 412 is transmitted can be reduced, thereby weakening the bonds between the vertical walls 418 and suppressing the appearance of vibrations of unnecessary frequencies.

[0054] In this embodiment, a plurality of active units 413A are arranged in the X direction between adjacent standing walls 418 arranged in the X direction, specifically, two active units 413A are arranged in the X direction between adjacent standing walls 418 arranged in the X direction. Note that the number of active units 413A arranged in the X direction between adjacent standing walls 418 arranged in the X direction may be two or more.

[0055] Here, the effect of the distance W1 between adjacent standing walls 418 on the piezoelectric actuator 22 will be described by comparing this embodiment with a comparative example.

[0056] First, a piezoelectric actuator 22A of a comparative example will be described with reference to FIG. As shown in FIG. 7, in the piezoelectric actuator 22A of the comparative example, the distance W1 between adjacent standing walls 418A is smaller than that in the piezoelectric actuator 22 of this embodiment, and one piezoelectric element 413 is disposed between adjacent standing walls 418A aligned in the X direction.

[0057] Next, the frequency spectra of the piezoelectric actuator 22A of the comparative example and the piezoelectric actuator 22 of the present embodiment will be described with reference to Fig. 8 and Fig. 9. Note that the frequency spectrum indicates what frequency vibrations are included and what intensity they have in the vibration to be measured.

[0058] 8, the frequency spectrum of the piezoelectric actuator 22A of the comparative example has a high intensity at the desired frequency of 3 to 4 MHz, but the intensity of vibration at other unnecessary frequencies is also high. This is because, as described above, in the piezoelectric actuator 22A, the distance W1 between adjacent standing walls 418A is small, and therefore when the vibration of the diaphragm 412 is transmitted to the standing walls 418A and the standing walls 418A vibrate, the vibration of the standing walls 418A is easily coupled between the adjacent standing walls 418A and resonates.

[0059] 9, the frequency spectrum of the piezoelectric actuator 22 of this embodiment has a higher intensity at a desired frequency of 3 to 4 MHz than that of the piezoelectric actuator 22A of the comparative example, and the intensity of vibrations of other unnecessary frequencies is lower. As described above, in this embodiment, the distance W1 between adjacent standing walls 418 arranged in the X direction is large, and the distance W1 between adjacent standing walls 418 arranged in the X direction is longer than the distance W2 between the active parts 413A of the piezoelectric elements 413 arranged in the X direction. Therefore, even if the vibration of the diaphragm 412 is transmitted to the standing walls 418 and the standing walls 418 vibrate, the vibration of the standing walls 418 is unlikely to be coupled between the adjacent standing walls 418, and the appearance of vibrations of unnecessary frequencies due to the resonance of the standing walls 418 can be suppressed.

[0060] In this embodiment, the plurality of standing walls 418 extend parallel to the Y direction perpendicular to the Z direction and are arranged side by side in the X direction, but the plurality of standing walls 418 may extend parallel to the X direction perpendicular to the Z direction and be arranged side by side in the Y direction. Even if the direction in which the standing walls 418 are arranged side by side is not limited to the Y direction along the Y axis which is the second axis, but is the X direction along the X axis which is the first axis, the same effect as this embodiment can be obtained by arranging the standing walls 418 and the active parts 413A so that the distance W1 between the adjacent standing walls 418 is longer than the distance W2 between the adjacent active parts 413A in the XY plane which is a plane including the Y axis which is the first axis perpendicular to the Z direction and the X axis which is the second axis.

[0061] As described above, according to this embodiment, the following effects can be obtained. The piezoelectric actuator 22 includes a vibration plate 412 having a first surface 412h that closes an opening 411A provided in a substrate 411 and a second surface 412r on which a plurality of piezoelectric elements 413 are provided, a suppression section 43 that suppresses vibration of the vibration plate 412, and a plurality of standing walls 418 that extend from the first surface 412h to the opening 411A. When a portion where the first electrode 414, the piezoelectric layer 415, and the second electrode 416 overlap is defined as an active section 413A of the piezoelectric element 413, the first electrode 414, the piezoelectric layer 415, and the second electrode 416 overlap each other. In plan view from the Z direction which is the lamination direction with the two electrodes 416, the standing walls 418 are provided between adjacent active parts 413A, and by making the distance W1 between adjacent standing walls 418 longer than the distance W2 between adjacent active parts 413A in the XY plane which is a plane perpendicular to the Z direction which is the lamination direction, the number of standing walls 418 to which the vibration of the diaphragm 412 is transmitted can be reduced, so that the bonds between the standing walls 418 can be weakened and the appearance of vibrations of unnecessary frequencies can be suppressed. This makes it possible to obtain a highly accurate piezoelectric actuator 22.

[0062] Furthermore, even if the vibration of vibration plate 412 is transmitted to standing wall 418 and causes standing wall 418 to vibrate, piezoelectric element 413 surrounded by suppression portion 43 can be treated as an isolated oscillator, so that piezoelectric actuator 22 with uniform frequency characteristics can be obtained.

[0063] Furthermore, since leakage of vibration energy from diaphragm 412 can be suppressed via upright wall 418, the Q value of piezoelectric element 413 can be increased, and piezoelectric actuator 22 with excellent vibration stability can be obtained.

[0064] 2. Embodiment 2 Next, a piezoelectric actuator 22B according to a second embodiment will be described with reference to Fig. 10 and Fig. 11. In the following description, differences from the first embodiment will be mainly described, and the same components as those in the first embodiment will be denoted by the same reference numerals, and duplicated descriptions will be omitted.

[0065] In the piezoelectric actuator 22B according to this embodiment, the distance W1 between the plurality of standing walls 418B is larger than that in the piezoelectric actuator 22 of the first embodiment.

[0066] 10 and 11, the standing walls 418B and the active parts 413A are arranged so that the distance W1 between adjacent standing walls 418B aligned in the X direction is longer than the distance W2 between adjacent active parts 413A of the piezoelectric elements 413 aligned in the X direction. Specifically, the multiple standing walls 418B are provided between the multiple channels CH aligned in the X direction in a plan view from the Z direction.

[0067] In this embodiment, six vibration regions in which the diaphragm 412 can vibrate due to the vibration of the active part 413A without being suppressed by the suppressing part 43 are arranged in the X direction between adjacent standing walls 418B arranged in the X direction.

[0068] In addition, in this embodiment, a plurality of active units 413A are arranged in the X direction between adjacent standing walls 418B arranged in the X direction. Specifically, six active units 413A are arranged in the X direction between adjacent standing walls 418B arranged in the X direction.

[0069] According to this embodiment, in addition to the effects of the first embodiment, the following effects can be obtained. Compared to the piezoelectric actuator 22 of embodiment 1, the piezoelectric actuator 22B has a larger distance W1 between the multiple standing walls 418B and a further reduced number of standing walls 418B to which the vibrations of the diaphragm 412 are transmitted, thereby further weakening the bonds between the standing walls 418 and further suppressing the emergence of vibrations of unnecessary frequencies. [Explanation of symbols]

[0070] 1...ultrasonic device and ultrasonic measuring device as electronic device, 2...ultrasonic probe, 3...cable, 10...control unit, 21...housing, 22, 22A, 22B...piezoelectric actuator, 23...circuit board, 24...ultrasonic element, 41...base, 42...sealing plate, 43...suppression unit, 43A...first suppression unit, 43B...second 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 portion, 414...first electrode, 414P...first electrode terminal, 415...piezoelectric layer, 416...second electrode, 416P...second electrode terminal, 418, 418A, 418B...standing wall, W1...distance between standing walls 418, W2...distance between active portions 413A, W3...distance between suppression portions 43.

Claims

1. A substrate having an opening formed therein; a diaphragm provided on the substrate, the diaphragm having a first surface closing the opening; A second surface of the diaphragm opposite to the first surface is provided in correspondence with the opening. A plurality of piezoelectric elements; a suppression section provided in correspondence with the piezoelectric element and configured to suppress vibration of the diaphragm; a plurality of standing walls extending from the first surface to the opening, The piezoelectric element is formed by laminating a first electrode, a piezoelectric layer, and a second electrode in this order from the second surface side, The suppression portion includes a plurality of first suppression portions formed to extend in a first direction and a plurality of second suppression portions formed to intersect with the first direction. and a plurality of second suppression portions formed extending in a second direction, the first direction is a short-side direction of the opening, The second direction is a longitudinal direction of the opening, The plurality of standing walls are arranged side by side in the second direction, The plurality of standing walls each extend parallel to the first direction, and one end of the standing walls is the other end is connected to the periphery of the opening, When a portion where the first electrode, the piezoelectric layer, and the second electrode overlap is defined as an active portion, In a plan view from the stacking direction, the standing wall is provided between the adjacent active parts, In a plane perpendicular to the stacking direction, the distance between the adjacent standing walls is longer than the distance between Between the adjacent standing walls in the second direction, two or more of the active parts are arranged in the second direction. be placed alongside Piezoelectric actuator.

2. The distance between adjacent standing walls is at least twice the distance between adjacent suppression portions. The piezoelectric actuator according to claim 1.

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

4. A piezoelectric actuator according to any one of claims 1 to 3; A transmission circuit for transmitting ultrasonic waves by the piezoelectric actuator; The piezoelectric actuator includes a receiving circuit for receiving ultrasonic waves. Ultrasonic element.

5. The ultrasonic element according to claim 4, A housing for housing the ultrasonic element. Ultrasonic probe.

6. The ultrasonic element according to claim 4, A control unit for controlling the ultrasonic element. Ultrasonic device.

7. A piezoelectric actuator comprising the piezoelectric actuator according to any one of claims 1 to 3. Electronic devices.

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