Ultrasonic element and ultrasonic device

Abstract

To provide an ultrasonic element that prevents damage to a diaphragm even when decompressed.SOLUTION: An ultrasonic element 1 comprises: a substrate 2 having an opening 7 formed therein; a diaphragm 3 provided on the substrate 2, having a first surface 3a in contact with the substrate 2, and closing the opening 7; piezoelectric elements 11 provided on a second surface 3b of the diaphragm 3 on the opposite side of the first surface 3a; a protective substrate 5 facing the second surface 3b and protecting the piezoelectric elements 11; and prevention parts 4 provided between the protective substrate 5 and the diaphragm 3 and preventing vibration of the diaphragm 3. The piezoelectric elements 11 each have a first electrode 12, a piezoelectric layer 13, and a second electrode 14 laminated in order from the second surface 3b. When a portion where the first electrode 12, the piezoelectric layer 13, and the second electrode 14 overlap is an active part 15, in plan view from a lamination direction 16, the prevention parts 4 are provided on the periphery of the active part 15, and a slit 18 is formed in each of the prevention parts 4.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to an ultrasonic element and an ultrasonic device. [Background technology]

[0002] Conventionally, ultrasonic elements in which piezoelectric elements are arranged in a matrix are known. For example, Patent Document 1 discloses an ultrasonic element that includes a silicon substrate having an opening, a vibration plate that closes the opening, and a piezoelectric element that is mounted on the vibration plate and has a piezoelectric body sandwiched between electrodes.

[0003] According to this, a diaphragm and a sealing plate are arranged opposite each other. A lattice-shaped suppression section is arranged between the diaphragm and the sealing plate, and a piezoelectric element is installed in the sealed space surrounded by the suppression section. The suppression section limits the range in which the diaphragm vibrates. The frequency at which the diaphragm vibrates is determined by the size of the diaphragm surrounded by the suppression section. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-188208 Summary of the Invention [Problem to be solved by the invention]

[0005] The sealed space surrounded by the diaphragm, sealing plate, and suppression unit is filled with air at atmospheric pressure. When the ultrasonic element is depressurized in a vacuum device to form an opening in the silicon substrate during the manufacturing process of the ultrasonic element, the air in the sealed space presses against the diaphragm. This poses a problem of damaging the diaphragm. Furthermore, in ultrasonic elements in which the space surrounded by the suppression unit is sealed, the air pressure in the sealed space changes due to deformation of the diaphragm. Because the energy that the piezoelectric element uses to vibrate the diaphragm is consumed in changing the air pressure in the sealed space, there is a problem in that the diaphragm cannot be vibrated efficiently. [Means for solving the problem]

[0006] The ultrasonic element comprises a substrate having an opening formed therein, a vibration plate provided on the substrate, having a first surface in contact with the substrate and closing the opening, a piezoelectric element provided on a second surface of the vibration plate opposite the first surface, a protective substrate facing the second surface and protecting the piezoelectric element, and a suppression section provided between the protective substrate and the vibration plate and suppressing vibration of the vibration plate, wherein the piezoelectric element has a first electrode, a piezoelectric layer, and a second electrode stacked in that order from the second surface, and when the portion where the first electrode, the piezoelectric layer, and the second electrode overlap is defined as an active section, in a planar view from the stacking direction, the suppression section is provided around the active section, and a slit is formed in the suppression section.

[0007] The ultrasonic element comprises a substrate having an opening formed therein, a vibration plate provided on the substrate, having a first surface in contact with the substrate and closing the opening, a piezoelectric element provided on a second surface of the vibration plate opposite the first surface, a protective substrate facing the second surface and protecting the piezoelectric element, and a suppression section provided between the protective substrate and the vibration plate and suppressing vibration of the vibration plate, wherein the piezoelectric element has a first electrode, a piezoelectric layer, and a second electrode stacked in that order from the second surface, and when the portion where the first electrode, the piezoelectric layer, and the second electrode overlap is defined as an active section, in a planar view from the stacking direction, the suppression section is provided around the active section, and a slit is formed in the protective substrate.

[0008] The ultrasonic device includes the ultrasonic element described above and a drive circuit that inputs a drive signal to the piezoelectric element. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of an ultrasonic element according to a first embodiment. [Figure 2] FIG. 2 is a schematic plan view showing the internal structure of an ultrasonic element. [Figure 3] FIG. 2 is a schematic cross-sectional side view showing the internal structure of the ultrasonic element. [Figure 4]FIG. 2 is a schematic cross-sectional side view showing the internal structure of the ultrasonic element. [Figure 5] 5A and 5B are schematic cross-sectional side views for explaining a manufacturing method of an ultrasonic element. [Figure 6] 5A and 5B are schematic cross-sectional side views for explaining a manufacturing method of an ultrasonic element. [Figure 7] FIG. 10 is a schematic plan view showing the internal structure of an ultrasonic element according to a second embodiment. [Figure 8] FIG. 2 is a schematic plan view showing the structure of a protection substrate. [Figure 9] FIG. 2 is a schematic cross-sectional side view showing the internal structure of the ultrasonic element. [Figure 10] FIG. 2 is a schematic cross-sectional side view showing the internal structure of the ultrasonic element. [Figure 11] FIG. 10 is a block diagram showing a schematic configuration of a distance measuring device according to a third embodiment. [Figure 12] FIG. 10 is a schematic perspective view showing the schematic configuration of an ultrasonic measurement device according to a fourth embodiment. [Figure 13] FIG. 1 is a block diagram showing a schematic configuration of an ultrasonic measurement device. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments will be described with reference to the drawings. Note that each component in each drawing is illustrated at a different scale so that it can be recognized in each drawing.

[0011] First embodiment In this embodiment, a characteristic example of an ultrasonic element will be described with reference to FIGS. 1 to 6. As shown in FIG. 1, the ultrasonic element 1 includes a substrate 2. A diaphragm 3, a suppression unit 4, and a protective substrate 5 are arranged on top of each other on the substrate 2. The ultrasonic element 1 is a rectangular plate. The directions along two sides of the rectangle are the X and Y directions. The thickness direction of the ultrasonic element 1 is the Z direction. The diaphragm 3 vibrates and transmits ultrasonic waves in the negative Z direction. The substrate 2 and the protective substrate 5 are made of silicon. The diaphragm 3 is made of silicon dioxide and zirconium dioxide. The suppression unit 4 is made of a resin material. The suppression unit 4 includes an air vent 6 on its surface on the negative X direction side. The air vent 6 changes the air pressure in the space formed inside the ultrasonic element 1 to atmospheric pressure.

[0012] Fig. 2 is a diagram of the ultrasonic element 1 with the protection substrate 5 removed. Fig. 3 is a cross-sectional view taken along line AA in Fig. 2. Fig. 4 is a cross-sectional view taken along line BB in Fig. 2.

[0013] As shown in Figures 2 to 4, an opening 7 is formed in the substrate 2, and the substrate 2 is frame-shaped. A diaphragm 3 that closes the opening 7 is provided on the substrate 2. A first surface 3a of the diaphragm 3 contacts the substrate 2. The diaphragm 3 has a structure in which a first vibrating member 8 and a second vibrating member 9 are laminated. The material of the first vibrating member 8 on the substrate 2 side is silicon dioxide. The material of the second vibrating member 9 on the suppression unit 4 side is zirconium dioxide.

[0014] The surface of the diaphragm 3 opposite to the first surface 3a is the second surface 3b. The second surface 3b is in contact with the suppression section 4. Piezoelectric elements 11 are provided in a matrix on the second surface 3b. The piezoelectric element 11 has a first electrode 12, a piezoelectric layer 13, and a second electrode 14 laminated in this order from the second surface 3b. The first electrodes 12, which are long in the Y direction, are arranged side by side in the X direction on the second surface 3b. The piezoelectric layer 13 is arranged on the first electrodes 12 at a predetermined interval. The second electrodes 14, which are long in the X direction, are arranged side by side in the Y direction overlapping the piezoelectric layer 13. The portion where the first electrodes 12, piezoelectric layer 13, and second electrodes 14 overlap is called the active section 15.

[0015] An AC voltage is applied between the first electrode 12 and the second electrode 14. The AC voltage causes the piezoelectric layer 13 to vibrate. The vibration of the piezoelectric layer 13 causes the diaphragm 3 to vibrate. Each of the piezoelectric elements 11 arranged in a matrix vibrates the diaphragm 3 in synchronization. Therefore, the ultrasonic element 1 can transmit ultrasonic waves with high intensity.

[0016] A suppression section 4 is provided between the protective substrate 5 and the diaphragm 3. The suppression section 4 suppresses vibration of the diaphragm 3. The direction in which the second electrode 14, the piezoelectric layer 13, and the first electrode 12 are stacked in this order from the protective substrate 5 side, that is, the -Z direction, is defined as stacking direction 16. In a plan view from stacking direction 16, the suppression section 4 is provided around the active section 15. Vibration of the diaphragm 3 is suppressed where the suppression section 4 and the diaphragm 3 come into contact.

[0017] The vibration mode of the diaphragm 3 is set by the suppression unit 4, and the natural frequency of the diaphragm 3 is set. The space surrounded by the suppression unit 4 is called the internal space 17. The diaphragm 3 vibrates easily in the internal space 17. The diaphragm 3 vibrates less easily in the suppression unit 4. For this reason, the boundary between the suppression unit 4 and the internal space 17 becomes a node of the diaphragm 3.

[0018] A protective substrate 5 is disposed on the positive side of the suppression unit 4 in the Z direction. The protective substrate 5 faces the second surface 3b and protects the piezoelectric element 11. An internal space 17 is surrounded by the diaphragm 3, the protective substrate 5, and the suppression unit 4.

[0019] A slit 18 is formed in the suppression section 4. An air passage 19 is formed on the outer periphery of the suppression section 4. The air passage 19 is connected to the slit 18 and the air vent 6. Therefore, the internal space 17 is in communication with the outside air via the slit 18, the air passage 19, and the air vent 6. Therefore, the air pressure in the internal space 17 is atmospheric pressure. The slit 18 may be shaped to provide a space from the protective substrate 5 to the diaphragm 3, or from the protective substrate 5 to the middle of the diaphragm 3. It may also be shaped to provide a space from the diaphragm 3 to the middle of the protective substrate 5.

[0020] According to the configuration of the ultrasonic element 1, the active part 15 of the piezoelectric element 11 vibrates the diaphragm 3. The suppression part 4 is arranged around the active part 15. The suppression part 4 is sandwiched between the diaphragm 3 and the protective substrate 5. A slit 18 is formed in the suppression part 4, so that gas in the internal space 17 surrounded by the suppression part 4 can move to the outside of the suppression part 4. Because the internal space 17 surrounded by the suppression part 4 is not sealed, the diaphragm 3 can be vibrated efficiently.

[0021] In a plan view from the stacking direction 16, the shape of the surface of the suppression unit 4 facing the active unit 15 is polygonal, and one end of the slit 18 is connected to a side of the polygon. In this embodiment, the shape of the surface of the suppression unit 4 facing the active unit 15 is a rectangle, as an example of a polygon. One end of the slit 18 is connected to a side of the rectangle. Alternatively, the shape of the surface of the suppression unit 4 facing the active unit 15 may be a polygon such as a triangle, pentagon, or hexagon.

[0022] According to the configuration of the ultrasonic element 1, one end of the slit 18 is connected to a side of the polygon, so that the diaphragm 3 can be vibrated more efficiently than when one end of the slit 18 is connected to a corner 21 of the polygon.

[0023] The corners 21 of the polygon on the surface of the suppression unit 4 facing the active unit 15 are formed in an arc shape. With this configuration, the corners 21 of the polygon are formed in an arc shape. The suppression unit 4 is made by thinning a resin material with a solvent and applying it in a predetermined shape. The solvent is then removed by drying. When the corners 21 are angular, stress is concentrated, making them prone to cracking. When the corners 21 are arc-shaped, cracking is less likely to occur. Therefore, cracking can be prevented from occurring in the corners 21 of the suppression unit 4 compared to when the polygonal corners 21 are formed in an angular shape.

[0024] Next, a manufacturing method of the ultrasonic element 1 will be described with reference to Figures 5 and 6. As shown in Figure 5, a substrate 22 is prepared. The material of the substrate 22 is silicon. A diaphragm 3 is placed on the substrate 22. First, a film forming device layers a silicon oxide layer (SiO2) on the surface of the substrate 22, and layers a zirconium oxide layer (ZrO2) on the surface of the silicon oxide layer. Sputtering or CVD (chemical vapor deposition) can be used as a method for layering materials.

[0025] The first electrode 12 is placed on the diaphragm 3. First, a film forming device forms a metal film on the diaphragm 3. In this embodiment, for example, the metal film is formed by laminating platinum on iridium oxide. Platinum is also called platinum. The metal film is formed by sputtering.

[0026] Next, a photosensitive resist is placed on the metal film, and an exposure device exposes the metal film by placing a mask in the shape of the first electrode 12 on top of it. Next, an etching device etches and removes part of the photosensitive resist, and then the metal film is etched using the resist as a mask, after which the resist is removed. As a result, the first electrode 12 is formed on the diaphragm 3. A dry etching method is used for etching.

[0027] Next, a ferroelectric material layer is placed on the first electrode 12. The ferroelectric material layer is the layer that will become the material for the piezoelectric layer 13, and is a PZT film layer. The ferroelectric material layer is placed using the sol-gel method. In the sol-gel method, a sol, which is a hydrated complex of hydroxides of titanium, zirconium, lead, etc., is created as the material for the ferroelectric material layer. The sol is applied to the diaphragm 3. This sol is dehydrated to form a gel. A baking device heats and bakes this gel to form a gel film made of an inorganic oxide. The application of the sol, dehydration, and baking are repeated. The gel films are stacked to form the ferroelectric material layer. Next, an annealing device anneals and prepares the ferroelectric material layer.

[0028] Next, the upper metal film is deposited. The upper metal film is made up of an iridium film, a titanium film, and another iridium film stacked in that order. The upper metal film is deposited by sputtering.

[0029] The ferroelectric material layer and the upper metal film are patterned into the shape of the piezoelectric layer 13. The patterning method is the same as that for the first electrode 12, and therefore a description thereof will be omitted.

[0030] Next, the second electrode 14 is placed. First, a film forming device forms a metal film. The metal film is formed by sputtering. The metal film is patterned into the shape of the second electrode 14. The patterning method is the same as that for the first electrode 12, so a description thereof will be omitted.

[0031] An inorganic film is disposed over the first electrode 12, the piezoelectric layer 13, and the second electrode 14. The inorganic film is an alumina (Al2O3) film, and is formed using the ALD (Atomic Layer Deposition) method. Next, the inorganic film is patterned into the shapes of the first electrode 12 and the second electrode 14. The patterning method is the same as that for the first electrode 12, and therefore a description thereof will be omitted.

[0032] Next, an organic insulating film is applied. First, a film-forming device applies an organic solid film on top of the inorganic film. The organic solid film is a photosensitive resin film. A solution containing a dissolved photosensitive resin material is applied to the substrate 22. A spin coater is used for application. Next, a drying device dries the solution to remove the solvent.

[0033] Next, the organic solid film is patterned into the shape of the suppression section 4. In this process, slits 18 are formed. The patterning method is the same as for the first electrode 12, so the explanation will be omitted. The suppression section 4 is formed on the diaphragm 3. The slits 18 are formed in the suppression section 4. Next, the protection substrate 5 is adhesively fixed onto the suppression section 4.

[0034] Next, the substrate 22 is patterned to form the opening 7. As shown in FIG. 6 , a film made of the material of the mask film 23 is placed on the negative surface of the substrate 22 in the Z direction by a film forming device. Then, the film made of the material of the mask film 23 is exposed and developed using a photolithography method, and the mask film 23 is formed by patterning the film made of the material of the mask film 23. The shape of the mask film 23 is the planar shape of the opening 7.

[0035] When a film made of the material of the mask film 23 is provided, the substrate 22 is placed in the chamber of a vacuum device and the pressure is reduced. When a film made of the material of the mask film 23 is patterned, the substrate 22 is also placed in the chamber of a vacuum device and the pressure is reduced.

[0036] Since slits 18 are formed in suppression unit 4, gas within internal space 17 surrounded by suppression unit 4 can move to the outside of suppression unit 4. Therefore, when the ultrasonic element 1 is depressurized, the air pressure within internal space 17 surrounded by suppression unit 4 becomes the same as the air pressure of the outside air. As a result, even if the ultrasonic element 1 is depressurized in the process of manufacturing the ultrasonic element 1, damage to the vibration plate 3 and base material 22 can be suppressed.

[0037] Next, the substrate 22 is etched using the mask film 23 as a mask. A wet anisotropic etching method is used as the etching method. The diaphragm 3 functions as an etching stop layer. Next, the mask film 23 is removed. As a result, an opening 7 is formed in the substrate 2 as shown in FIG. 3. The ultrasonic element 1 is completed through the above steps.

[0038] Second embodiment This embodiment differs from the first embodiment in that a portion corresponding to the slit 18 is formed in the protection substrate 5. Note that the same components as those in the first embodiment are denoted by the same reference numerals, and redundant explanations will be omitted.

[0039] Fig. 7 is a diagram in which the protective substrate has been removed from the ultrasonic element 26. Fig. 8 is a diagram in which the protective substrate is viewed from the substrate 2 side. Fig. 9 is a diagram in which the protective substrate is viewed from the cross-sectional side along line CC in Fig. 7. Fig. 10 is a diagram in which the protective substrate is viewed from the cross-sectional side along line DD in Fig. 7.

[0040] As shown in Figures 7, 9, and 10, in ultrasonic element 26, suppression section 27 is provided on diaphragm 3. No slits are formed in suppression section 27. As shown in Figures 9 and 10, protection substrate 28 is provided on suppression section 27. No slits 18 are formed in suppression section 27.

[0041] As shown in Fig. 8, slits 29, ventilation paths 31, and ventilation holes 32 are formed in protective substrate 28. As shown in Figs. 8 to 10, internal space 17 communicates with the outside air via slits 29, ventilation paths 31, and ventilation holes 32. The air pressure in internal space 17 is atmospheric pressure. In the thickness direction of protective substrate 28, slits 29 are groove-shaped and do not penetrate protective substrate 28.

[0042] According to the configuration of the ultrasonic element 26, the active part 15 of the piezoelectric element 11 vibrates the diaphragm 3. A suppression part 27 is disposed around the active part 15. The suppression part 27 is sandwiched between the diaphragm 3 and a protective substrate 28. A slit 29 is formed in the protective substrate 28, so that gas in the internal space 17 surrounded by the suppression part 27 can move to the outside of the suppression part 27. Therefore, when the pressure in the ultrasonic element 26 is reduced, the air pressure in the internal space 17 surrounded by the suppression part 27 becomes the same as the air pressure on the first surface 3a side of the diaphragm 3. Therefore, even if the pressure in the ultrasonic element 26 is reduced during the manufacturing process of the ultrasonic element 26, damage to the diaphragm 3 can be reduced. Furthermore, because the internal space 17 surrounded by the suppression part 27 is not sealed, the diaphragm 3 can be vibrated efficiently.

[0043] Third embodiment In this embodiment, an example of an ultrasonic device in which the ultrasonic element 1 or the ultrasonic element 26 is installed will be introduced. 11 , a distance measurement device 35 serving as an ultrasonic device of this embodiment includes an ultrasonic element 36 and a control unit 37 that controls the ultrasonic element 36. The control unit 37 includes a drive circuit 38 that drives the piezoelectric element 11 and a calculation unit 46 that calculates transmission signals and reception signals. In the distance measurement device 35, the drive circuit 38 of the control unit 37 controls the ultrasonic element 36, and the ultrasonic element 36 transmits ultrasonic waves. When the ultrasonic waves are reflected by an object and the ultrasonic element 36 receives the reflected waves, the control unit 37 calculates the distance from the ultrasonic element 36 to the object based on the time from the transmission timing of the ultrasonic waves to the reception timing of the ultrasonic waves.

[0044] The drive circuit 38 is a driver circuit for controlling the drive of the ultrasonic element 36, and includes a reference potential circuit 39, a switching circuit 41, a transmitting circuit 42, a receiving circuit 43, and the like.

[0045] The reference potential circuit 39 is connected to the common electrode pad 44 of the ultrasonic element 36, and applies a reference potential to each piezoelectric element 11 via wiring within the ultrasonic element 36. The reference potential is determined so that one of the AC potentials does not become negative.

[0046] The switching circuit 41 is connected to the drive electrode pad 45, the transmission circuit 42, and the reception circuit 43. The switching circuit 41 is configured with a switching circuit, and switches between a transmission connection that connects the drive electrode pad 45 and the transmission circuit 42 and a reception connection that connects the drive electrode pad 45 and the reception circuit 43.

[0047] The transmission circuit 42 is connected to the switching circuit 41 and the calculation unit 46. When the switching circuit 41 is switched to the transmission connection, the transmission circuit 42 inputs a pulse waveform drive signal to the piezoelectric element 11 in the ultrasonic element 36 under the control of the calculation unit 46, causing the ultrasonic element 36 to transmit an ultrasonic wave. Therefore, the distance measurement device 35 includes a drive circuit 38 that inputs a drive signal to the ultrasonic element 36 and the piezoelectric element 11. The ultrasonic element 36 is either the ultrasonic element 1 or the ultrasonic element 26.

[0048] The receiving circuit 43 is connected to the switching circuit 41 and the calculation unit 46. When the piezoelectric element 11 receives an ultrasonic wave, the piezoelectric element 11 outputs a received signal. When the switching circuit 41 is switched to the receiving connection, the receiving circuit 43 receives the received signal output by the piezoelectric element 11 in the ultrasonic element 36 and transmits it to the calculation unit 46 based on the control of the calculation unit 46.

[0049] According to the configuration of distance measurement device 35, a drive signal output by drive circuit 38 is input to piezoelectric element 11, and ultrasonic element 36 transmits ultrasonic waves. A reception signal corresponding to the ultrasonic waves received by piezoelectric element 11 is input to drive circuit 38. This ultrasonic element 36 is an element that can prevent damage to diaphragm 3 and can efficiently vibrate diaphragm 3. Therefore, distance measurement device 35 can be a device that includes ultrasonic element 36 that can prevent damage to diaphragm 3 and can efficiently vibrate diaphragm 3.

[0050] Fourth embodiment In this embodiment, an example of an ultrasonic device in which the ultrasonic element 1 or the ultrasonic element 26 is installed will be introduced. 12, an ultrasonic measuring device 49 as an ultrasonic device includes an ultrasonic probe 50 and a control device 52 electrically connected to the ultrasonic probe 50 via a cable 51. The ultrasonic probe 50 of the ultrasonic measuring device 49 is placed in contact with the surface of a living body such as a human body, and transmits ultrasonic waves into the living body. The ultrasonic probe 50 then receives ultrasonic waves reflected by organs within the living body. Based on the received signals, the control device 52 forms an internal tomographic image of the living body and measures the state of the organs within the living body, such as blood flow.

[0051] The ultrasonic probe 50 corresponds to an ultrasonic probe. The ultrasonic probe 50 includes a housing 53, an ultrasonic element 54 housed inside the housing 53, and a circuit board on which a driver circuit for controlling the ultrasonic element 54 is provided. The ultrasonic element 54, the circuit board, and the like constitute an ultrasonic sensor 55, and the ultrasonic sensor 55 constitutes an ultrasonic module.

[0052] The housing 53 is a rectangular box in a plan view. A sensor window 53b is provided on a sensor surface 53a facing one side in the thickness direction of the housing 53. A part of the ultrasonic element 54 is exposed in the sensor window 53b. A passage hole 53c for the cable 51 is provided on the side of the housing 53, and the cable 51 enters the inside of the housing 53 from the passage hole 53c and is connected to a circuit board inside the housing 53. The cable 51 communicates between the control device 52 and the ultrasonic probe 50.

[0053] The control device 52 includes an operation unit 56 and a display unit 57. The operation unit 56 is a UI (user interface) that allows the user to operate the ultrasonic measurement device 49, and is configured, for example, by a touch panel provided on the display unit 57, operation buttons, a keyboard, a mouse, etc. The display unit 57 is configured, for example, by a liquid crystal display, etc., and displays images.

[0054] 13, the ultrasonic elements 54 are electrically connected to a circuit board 58 serving as a drive circuit included in the ultrasonic sensor 55. A driver circuit and the like for controlling the ultrasonic elements 54 are provided on the circuit board 58. The circuit board 58 includes a selection circuit 59, a transmission circuit 61, and a reception circuit 62.

[0055] The first electrodes 12 drawn out from the respective piezoelectric elements 11 are connected to the selection circuit 59. Based on the control of the control device 52, the selection circuit 59 switches between a transmission connection that connects the ultrasonic elements 54 and the transmission circuit 61 and a reception connection that connects the ultrasonic elements 54 and the reception circuit 62.

[0056] When switched to a transmission connection under the control of the control device 52, the transmission circuit 61 outputs a transmission signal to the ultrasonic element 54 via the selection circuit 59 to cause the ultrasonic element 54 to transmit ultrasonic waves. When switched to a reception connection under the control of the control device 52, the reception circuit 62 outputs a reception signal input from the ultrasonic element 54 to the control device 52 via the selection circuit 59. The reception circuit 62 is configured to include a low-noise amplifier circuit, a voltage-controlled attenuator, a programmable gain amplifier, a low-pass filter, an A / D converter, etc. The reception circuit 62 performs various signal processing such as converting the reception signal to a digital signal, removing noise components, and amplifying the signal to a desired signal level, and then outputs the processed reception signal to the control device 52.

[0057] The control device 52 includes an operation unit 56, a display unit 57, a storage unit 63, and a calculation unit 64. The control device 52 may be a terminal device such as a tablet terminal, a smartphone, or a personal computer, or may be a dedicated terminal device for operating the ultrasound probe 50. The control device 52 controls each of the piezoelectric elements 11.

[0058] The storage unit 63 stores various programs and various data for controlling the ultrasonic measurement device 49. The calculation unit 64 is composed of a calculation circuit such as a CPU (Central Processing Unit) and a storage circuit such as a memory. The calculation unit 64 reads and executes the various programs stored in the storage unit 63, thereby controlling the generation and output processing of a transmission signal for the transmission circuit 61. Furthermore, the calculation unit 64 controls the reception circuit 62 to set the frequency and gain of the reception signal, etc.

[0059] The transmission circuit 61 is electrically connected to the selection circuit 59 and the calculation unit 64. When the selection circuit 59 is switched to the transmission connection, the pulse waveform drive signal output by the transmission circuit 61 is input to the piezoelectric element 11 in the ultrasonic element 54 based on the control of the calculation unit 64, and the ultrasonic element 54 transmits an ultrasonic wave. Therefore, the ultrasonic measurement device 49 includes a circuit board 58 that inputs the drive signal to the piezoelectric element 11. The ultrasonic element 54 is either the ultrasonic element 1 or the ultrasonic element 26.

[0060] The receiving circuit 62 is connected to the selection circuit 59 and the calculation unit 64. When the piezoelectric element 11 receives an ultrasonic wave, the piezoelectric element 11 outputs a received signal. When the selection circuit 59 is switched to the receiving connection, the receiving circuit 62 receives the received signal output by the piezoelectric element 11 in the ultrasonic element 54 and transmits it to the calculation unit 64 based on the control of the calculation unit 64.

[0061] According to the configuration of ultrasonic measurement device 49, a drive signal output by circuit board 58 is input to piezoelectric element 11, and ultrasonic element 54 transmits ultrasonic waves. A reception signal corresponding to the ultrasonic waves received by piezoelectric element 11 is input to circuit board 58. This ultrasonic element 54 is an element that can prevent damage to diaphragm 3 and can efficiently vibrate diaphragm 3. Therefore, ultrasonic measurement device 49 can be a device that includes ultrasonic element 54 that can prevent damage to diaphragm 3 and can efficiently vibrate diaphragm 3. [Explanation of symbols]

[0062] 1,26,36,54...ultrasonic element, 2...substrate, 3...vibration plate, 3a...first surface, 3b...second surface, 4,27...suppression section, 5,28...protective substrate, 7...opening, 11...piezoelectric element, 12...first electrode, 13...piezoelectric layer, 14...second electrode, 15...active section, 16...stacking direction, 18,29...slit, 21...corner, 35...distance measuring device as ultrasonic device, 38...drive circuit, 49...ultrasonic measuring device as ultrasonic device, 58...circuit board as drive circuit.

Claims

1. a substrate having an opening formed therein; a vibration plate provided on the substrate, having a first surface in contact with the substrate, and closing the opening; a plurality of piezoelectric elements provided on a second surface of the vibration plate opposite to the first surface; a protection substrate facing the second surface and protecting the piezoelectric element; a suppression section provided between the protection substrate and the diaphragm to suppress vibration of the diaphragm; Equipped with The plurality of piezoelectric elements are formed by laminating a first electrode, a piezoelectric layer, and a second electrode in this order from the second surface, When the 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 suppression section are provided around the a slit is formed in each of the suppression portions corresponding to the plurality of piezoelectric elements; The internal space surrounded by the diaphragm, the protection substrate, and the suppression portion is An ultrasonic element that is in communication with the outside air outside the suppression section.

2. The ultrasonic element according to claim 1, In a plan view from the stacking direction, the shape of the surface of the suppression section facing the active section is polygonal. 、 An ultrasonic element, wherein one end of the slit is connected to a side of the polygon.

3. The ultrasonic element according to claim 2, The ultrasonic element is characterized in that corners of the polygon are formed in an arc shape.

4. The ultrasonic element according to any one of claims 1 to 3. a drive circuit that inputs drive signals to the plurality of piezoelectric elements. Ultrasonic device.

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