Piezoelectric transducer and electroacoustic device

Abstract

To provide a piezoelectric transducer capable of enhancing directivity as compared with before, capable of improving sound pressure, and capable of reducing the influence of the atmospheric pressure, and an electroacoustic device.SOLUTION: An ultrasonic transducer 100 includes a substrate 10 including a frame 11 and a space 40; and a vibrator 20 including a plurality of beams 17 connecting the frame 11 of the substrate 10 with one end part, a core part 21 arranged at a gap with the inner peripheral surface 11h of the frame 11 in the space 40 in noncontact, including a lower electrode 14, an upper electrode 18 and a piezoelectric layer 16 sandwiched between the lower electrode 14 and the upper electrode 18 and connected with the other end parts of the plurality of the beams 17; and a plurality of cantilever beams 22 extended outward from an outer peripheral part except portions connected with the plurality of beams 17 of the core part 21; and a column 30 having an end connected to the core part 21 of the vibrator 20 in the space 40 in the longitudinal direction and arranged distant from the inner peripheral surface 11h of the frame 11.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a piezoelectric transducer and an electroacoustic device using the same. [Background technology]

[0002] Conventionally, the piezoelectric micromachined ultrasonic transducer (pMUT) has been known as a piezoelectric transducer. pMUTs are devices capable of transmitting and receiving ultrasonic waves, with piezoelectric bodies and electrodes formed minutely on a substrate using MEMS technology. pMUTs have a membrane on a substrate with a piezoelectric body sandwiched between a pair of electrodes, and a cavity in the substrate makes the membrane easily vibrate and deflect. pMUTs utilize the inverse piezoelectric effect, in which a material deforms when a voltage is applied to the electrodes, and the piezoelectric effect, in which voltage is generated by the deformation of the material. pMUTs can transmit and receive ultrasonic waves through the flexural vibration of the membrane caused by the inverse piezoelectric effect and the piezoelectric effect, and are used in distance measuring sensors, fingerprint sensors, etc.

[0003] The resonant frequency of a pMUT is defined by physical properties such as the membrane diameter, film thickness, and Young's modulus. Furthermore, changes in the initial deformation of the membrane cause changes in the apparent Young's modulus, which in turn changes the resonant frequency. One factor that changes the initial deformation of the membrane is air pressure. Since the area between the membrane and the circuit board of a mounted pMUT is sealed, it is thought that a difference in air pressure between the area between the membrane and the circuit board and the outside of the membrane is likely to occur. For this reason, it is desirable for a pMUT to have a structure that is less susceptible to air pressure differences and less likely to change the initial deformation of the membrane.

[0004] The technology described in Patent Document 1 has a configuration in which four triangular membranes are combined into a square shape, with the outer edge of each membrane fixed. In this configuration, when a voltage is applied, the center parts of the four membranes forming the square shape are displaced up and down to transmit or receive ultrasonic waves.

[0005] The technology described in Patent Document 2 has a configuration in which a central anchor structure is disposed between a piezoelectric layer stack, which corresponds to a membrane, and a substrate. Furthermore, a cavity is provided between the piezoelectric layer stack and the substrate. With this configuration, the central portion of the lower surface of the piezoelectric layer stack is supported by the central anchor, and when a voltage is applied, the outer portion of the membrane from the center displaces up and down around the central anchor. This allows ultrasonic waves to be transmitted and received. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 5936154 [Patent Document 2] Patent No. 6599968 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the technology of Patent Document 1 discloses an ultrasonic transducer that has low-frequency sensitivity regardless of residual stress, but when used to transmit ultrasonic waves, there is a problem that the sound pressure per element mounting area is low. Furthermore, because multiple membranes are combined with almost no gaps, there is a problem that the initial deformation of the membranes is greatly affected by air pressure. Furthermore, the technology of Patent Document 2 has a problem that the directionality of the acoustic characteristics is low. The present invention has been made in consideration of the above-mentioned problems, and aims to provide a piezoelectric transducer and an electroacoustic device that can increase directivity, improve sound pressure, and reduce the influence of air pressure compared to conventional devices. [Means for solving the problem]

[0008] The present invention is a piezoelectric transducer comprising: a substrate having a gap; a connector connected to the substrate and provided above at least a portion of the gap; a piezoelectric body provided above at least a portion of the gap and including a first electrode, a second electrode, and a piezoelectric body sandwiched between the first electrode and the second electrode; a vibrating body having a core connected to the connector and a cantilever extending outward from an outer periphery of the core other than the connection portion with the connector; and a pillar extending longitudinally including one end and connected to the core at the one end. In the above configuration, the vibrating body may have a plurality of cantilevers extending radially from the core portion when viewed in a plan view. In the above configuration, the cantilever beam may be substantially fan-shaped or substantially triangular in plan view. In the above configuration, the vibrating body and the substrate are connected by one connecting body, and the vibrating body may be configured to have one cantilever beam that is formed to surround the core portion except for the portion that connects to the connecting body when viewed in a plane, and has an approximately fan-shaped shape including the core portion.

[0009] In the above configuration, the vibrating body and the substrate may be connected by a plurality of the connecting bodies, one end of each of the connecting bodies being connected between two circumferentially adjacent cantilevers on the outer periphery of the core, and the other end being connected to the substrate, and each of the cantilevers and each of the connecting bodies may be configured to be non-contact with each other. In the above configuration, the plurality of cantilevers may have the same thickness and shape but different radially extending lengths. In the above configuration, a line may be formed on the connector, the line being routed from one of the first electrode and the second electrode on the side of the vibrating body opposite to the pillar side to the substrate.

[0010] The present invention is an electroacoustic device comprising a housing having an opening, one of the piezoelectric transducers described above arranged within the housing, and a control unit arranged within the housing for controlling the operation of the piezoelectric transducer, wherein the opening is configured to be large enough to contain the vibrating body when viewed in a plane, and the piezoelectric transducer is arranged within the housing so that the other end of the pillar and the pillar-side surface of the vibrating body face the outside of the housing through the opening. The above-described configuration may further include a column support portion that supports the column on the housing without covering a vibrating portion of the vibrating body. [Effects of the Invention]

[0011] According to the present invention, it is possible to increase the directivity, improve the sound pressure, and reduce the influence of air pressure compared to the prior art. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1(a) is a plan view of an ultrasonic transducer according to a first embodiment, (b) is a cross-sectional view taken along line AA' in (a), and (c) is a cross-sectional view taken along line BB' in (a). [Figure 2] 1(a) is a plan view in which the wiring pattern is removed from FIG. 1(a), and FIG. 1(b) is a bottom view of FIG. 1(a). [Figure 3] FIG. 2 is a cross-sectional view for explaining the operation of the ultrasonic transducer according to the first embodiment. [Figure 4A] 2A to 2C are cross-sectional views illustrating a method for manufacturing the ultrasonic transducer according to the first embodiment. [Figure 4B] 2A to 2C are cross-sectional views illustrating a method for manufacturing the ultrasonic transducer according to the first embodiment. [Figure 5] FIG. 1 is a diagram showing a list of parameters for comparing and explaining the performance of the ultrasonic transducer 100 according to the first embodiment and the performance of an acoustic transducer according to the prior art. [Figure 6] 10A and 10B are diagrams showing the configuration of an ultrasonic transducer according to a second embodiment, where (a) is a plan view and (b) is a bottom view. [Figure 7] 10A and 10B are diagrams showing the configuration of an ultrasonic transducer according to a third embodiment, where (a) is a plan view and (b) is a bottom view. [Figure 8] 10A and 10B are diagrams showing the configuration of an ultrasonic transducer according to a fourth embodiment, where (a) is a plan view and (b) is a bottom view. [Figure 9] 10A and 10B are diagrams showing the configuration of an electroacoustic device according to a fifth embodiment, in which (a) is a side cross-sectional view and (b) is a plan view. [Figure 10] 10A and 10B are diagrams showing the configuration of an electroacoustic device according to a sixth embodiment, in which (a) is a side cross-sectional view and (b) is a plan view. DETAILED DESCRIPTION OF THE INVENTION

[0013] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The embodiment described below is an example of a means for realizing the present invention, and should be appropriately modified or changed depending on the configuration of the device to which the present invention is applied and various conditions, and the present invention is not limited to the embodiment described below.

[0014] In addition, in the following description of the drawings, the same or similar parts are designated by the same or similar reference numerals. However, it should be noted that the drawings are schematic, and the vertical and horizontal dimensions and scales of the components or parts may differ from those of the actual parts. Therefore, the specific dimensions and scales should be determined by taking into consideration the following explanation. Furthermore, it goes without saying that the dimensional relationships and ratios may differ between the drawings. [First embodiment] First, a first embodiment of the present invention will be described, with reference to Figures 1 to 5 showing the first embodiment. 〔composition〕 In the first embodiment, a case will be described in which a piezoelectric transducer according to the present invention is applied to an ultrasonic transducer that transmits and receives ultrasonic waves.

[0015] Fig. 1(a) is a plan view of an ultrasonic transducer 100 according to a first embodiment, Fig. 1(b) is a cross-sectional view taken along line A-A' in Fig. 1(a), Fig. 1(c) is a cross-sectional view taken along line B-B' in Fig. 1(a). Fig. 2(a) is a plan view of Fig. 1(a) from which an upper electrode and a wiring pattern have been removed, and Fig. 2(b) is a bottom view of Fig. 2(a). 1(a) to 1(c), the height direction of the ultrasonic transducer 100 is the Z direction, the width direction is the X direction, and the direction perpendicular to the Z direction and the X direction is the Y direction. The same applies to Figures 2 and onwards. The ultrasonic transducer 100 includes a substrate 10, a plurality of beams 17, a vibrating body 20, a cylinder 30, wiring 50, and electrode pads 52 and . The substrate 10 includes a frame 11 and a cavity 40 . The frame 11 has a first surface 11a on the +Z direction side and a second surface 11b on the -Z direction side. The void 40 is formed penetrating the plate surface at a position in the center of the substrate 10 in the X direction and slightly in the -Y direction from the center of the substrate 10. In the first embodiment, the void 40 is formed as a through-hole provided in the substrate 10. The frame 11 is a portion that surrounds the cavity 40 of the substrate 10 . The void 40 is an integrated space consisting of a first void 40a above the top end of the cylinder 30 and a second void 40b below the top end of the cylinder 30. The void 40 has a substantially circular shape when viewed from above. The beams 17 connect the frame 11 of the substrate 10 and the vibrating body 20 . The vibrating body 20 includes an upper electrode 18, a piezoelectric layer 16, a lower electrode 14, and a vibration assisting layer 12c, a core 21 connected to multiple beams 17, and multiple cantilever beams 22 extending outward from the outer periphery of the core 21 except for the portion connected to the beams 17. The following description will be given assuming the presence of the vibration assisting layer 12c, but this is not required. The vibration assisting layer 12c, the lower electrode 14, and the piezoelectric layer 16 are stacked in this order from the bottom up. A layer of, for example, SiO2 may be present between these layers. An upper electrode 18 is provided on the piezoelectric layer 16 only in the approximate center when viewed in a plan view. Here, the vibration assisting layer 12c is a layer for promoting the bending of the other laminated portions of the vibrating body 20. The core 21 is located approximately in the center when the vibrating body 20 is viewed in a plan view from the stacking direction. The core 21 serves as a fixed end of the multiple cantilevers 22. A cylinder 30 that extends in the Z direction and has a circular shape when viewed in a plan view is provided within the gap 40b of the core 21. One end of the cylinder 30 is connected to the core 21.

[0016] The vibrating body 20 is arranged in the first gap 40a with the upper electrode 18 facing the +Z direction. The vibrating body 20 is connected to the inner peripheral surface 11h of the frame 11 by a plurality of beams 17, but is arranged in a non-contact state with the inner peripheral surface 11h of the frame 11. The core portion 21 is a substantially cylindrical portion at the center of the vibrating body 20, as shown by the circled portion and frame portion surrounded by the dashed line in FIGS. 1(a) to 1(c) and FIG. 2(a).

[0017] 1(a), 2(a) and 2(b), the multiple cantilevers 22 are configured by, for example, four cantilevers 22. Each cantilever 22 is formed integrally with the core 21 and has a generally fan-like shape when viewed from above. The fan-top side of each cantilever 22 is connected to the outer circumferential surface of the core 21, and extends into the first gap 40a with the arc side facing radially outward. In the example shown in Figures 1(a), 2(a) and (b), the four cantilevers 22 are each configured to have the same shape and size and are arranged at equal intervals along the circumferential direction of the core 21. A gap is formed between the end faces of the four cantilevers 22 on the arc side and the inner peripheral surface 11h of the frame 11. In other words, the end faces of the four cantilevers 22 on the arc side and the inner peripheral surface 11h are not in contact with each other.

[0018] In the example shown in FIGS. 1(a), 2(a) and 2(b), the beams 17 are configured by, for example, four beams 17. Each beam 17 has a strip shape when viewed in a plan view. The shape of each beam 17 can be configured as a rectangular parallelepiped, a cylindrical column, a prism, or the like, but it is preferable that the shape has a flat surface at the position where the wiring 50 is to be provided. As an example, each beam 17 is configured as a rectangular parallelepiped. Each beam 17 has one longitudinal end connected to the portion between two circumferentially adjacent cantilever beams 22 on the outer peripheral surface of the core 21, and the other end connected to the inner peripheral surface 11h of the frame 11. That is, the vibrating body 20 and the column 30 are supported by the frame 11 by the four beams 17 . The four beams 17 are arranged so that if they were virtually extended and intersected, they would form a cross or X shape. The widths of the four beams 17 are all the same, and the lengths of the beams 17 are all the same. Furthermore, the four beams 17 and the four cantilevers 22 are not in contact with each other, and gaps are formed between the four beams 17 and the four cantilevers 22.

[0019] The upper electrode 18 of the vibrating body 20 is formed across the upper surface of the core 21, the upper surfaces of the fan apex-side ends of the four cantilevers 22, and the upper surfaces of the core 21-side ends of the four beams 17. That is, the upper electrode 18 is substantially circular when viewed in a plan view, but notches are formed on the outer radial edge when the four beams 17 and the four cantilevers 22 are formed. This prevents the upper electrode 18 from interfering with the vibration action of the four cantilevers 22.

[0020] 1(b) and 1(c) and 2(b), the cylinder 30 is cylindrical, and one end on the +Z direction side is connected to the −Z direction end of the core 21 of the vibrating body 20. Furthermore, the other end on the −Z direction side of the cylinder 30 extends into the second gap 40b facing the −Z direction, and is a free end. In the example shown in Figures 1(a) and 2(a), the wiring 50 is formed on the upper surface of one of the four beams 17 that extends from the core 21 in the -Y direction, and is configured so that one end is connected to the upper electrode 18 and the other end is connected to the electrode pad 52.

[0021] The electrode pads 52 and 54 are square in shape when viewed from above and are made of, for example, titanium or platinum. The electrode pad 52 is electrically connected to the upper electrode through wiring 50, and the electrode pad 54 is electrically connected to the lower electrode 14 (described later) through, for example, a via. [Detailed configuration and components] Next, the detailed configuration and members of each component of the ultrasonic transducer 100 will be described. As shown in FIGS. 1(b) and 1(c), the frame 11 has a configuration in which a thermal oxide film 13, a lower electrode 14, and a piezoelectric layer 16 are laminated on a support substrate 12. The support substrate 12 is, for example, an SOI (Silicon on Insulator) substrate, and is configured such that a silicon oxide film (SiO2 film) 12b is formed on a silicon substrate 12a, and a silicon layer 12c is further formed on the silicon oxide film 12b. The silicon layer 12c serves as a vibration assisting layer. The thermal oxide film 13 is made of, for example, a silicon oxide film.

[0022] The lower electrode 14 is a metal film such as ruthenium, molybdenum, gold, titanium, platinum, aluminum, copper, chromium, silver, or palladium, or a laminated film made of a plurality of films selected from these. In the example shown in Figures 1(b) and 1(c), the lower electrode 14 is made of a laminated film. For example, the lower electrode 14 is made of a laminated film of a first metal film 14a made of chromium and a second metal film 14b made of ruthenium.

[0023] The piezoelectric layer 16 is made of, for example, PZT (lead zirconate titanate), KNN (potassium sodium niobate), BiFeO3 (bismuth ferrate), BaTiO3 (barium titanate), AlN (aluminum nitride), LiNbO3 (lithium niobate), LiTaO3 (lithium tantalate), ZnO (zinc oxide), or PVDF (polyvinylidene fluoride). As an example, the piezoelectric layer 16 is made of AlN.

[0024] The beams 17 are configured, for example, by sharing the silicon oxide film 12b and the silicon layer 12c in the support substrate 12 that constitutes the frame 11. That is, the thermal oxide film 13, the lower electrode 14, and the piezoelectric layer 16 are stacked on the silicon layer 12c that is formed on the silicon oxide film 12b.

[0025] The cylinder 30 is formed, for example, by utilizing the silicon substrate 12a in the support substrate 12 that constitutes the frame 11. Specifically, the silicon substrate 12a is formed by deep trench processing, for example, by deep reactive ion etching (DRIE). After the deep trench processing, the cylinder 30 becomes a separate body from the frame 11. Furthermore, the deep trench processing forms a second void 40b.

[0026] The vibrating body 20 has a configuration in which a thermal oxide film 13, a lower electrode 14, a piezoelectric layer 16, and an upper electrode 18 are laminated on a bonding layer that bonds the cylinder 30 and the vibrating body 20. The portions of the vibrating body 20 other than the upper electrode 18 are formed using the silicon oxide film 12b, silicon layer 12c, thermal oxide film 13, lower electrode 14, and piezoelectric layer 16 that constitute the frame 11. Specifically, each cantilever beam 22 and first gap 40a are formed by deep engraving processing similar to that for the cylinder 30. A plurality of beams 17 are also formed by this deep engraving processing. That is, in the vibrating body 20, the lower electrode 14 and the upper electrode 18 are formed so as to sandwich the piezoelectric layer 16 therebetween.

[0027] The upper electrode 18 has the same configuration as the lower electrode 14, but when a structure in which two types of metals are stacked is used, the order of stacking is reversed to that of the lower electrode 14. In the example shown in Figures 1(b) and 1(c), the upper electrode 18 is composed of a stacked film. As an example, the upper electrode 18 is composed of a stacked film of a third metal film 18a composed of ruthenium and a fourth metal film 18b composed of chromium. [Operation] Next, the operation of the ultrasonic transducer 100 will be described. FIG. 3 is a cross-sectional view for explaining the operation of the ultrasonic transducer 100. As shown in FIG. Although not shown, the operation of the ultrasonic transducer 100 is controlled by, for example, a control unit separately provided on a printed circuit board.

[0028] The control unit applies an AC voltage between the lower electrode 14 and the upper electrode 18 via the electrode pads 52 and 54 and the wiring 50. When an AC voltage is applied between the lower electrode 14 and the upper electrode 18, the cantilever 22 of the vibrating body 20 repeatedly vibrates alternately in the +Z direction and the −Z direction, as shown by the arrows in FIG. Specifically, for example, negative and positive voltages are applied to the lower electrode 14 and the upper electrode 18, respectively. Due to the inverse piezoelectric effect, strain is generated in the plane of the piezoelectric layer 16 such that the piezoelectric layer 16 contracts. This causes the cantilever 22 to expand in either the +Z direction or the −Z direction. Furthermore, for example, positive and negative voltages are applied to the lower electrode 14 and the upper electrode 18, respectively. Due to the inverse piezoelectric effect, a strain occurs in the piezoelectric layer 16 such that the piezoelectric layer 16 expands in the planar direction within the piezoelectric layer 16. This causes the cantilever 22 to expand in the other of the +Z direction and the −Z direction.

[0029] The cantilever 22 repeatedly vibrates in the direction of the arrow due to repeated swelling in the +Z direction and the -Z direction caused by the inverse piezoelectric effect, causing ultrasonic waves to be emitted from the vibrating body 20. In the example shown in Fig. 3, ultrasonic waves are emitted in the -Z direction from the cylinder 30 side.

[0030] On the other hand, when ultrasonic waves are received, the cantilever beam 22 vibrates in the direction of the arrow. This causes distortion in the piezoelectric layer 16. Due to the piezoelectric effect, an AC voltage is generated between the lower electrode 14 and the upper electrode 18. By measuring this AC voltage, ultrasonic waves can be received. [Manufacturing method] Next, a method for manufacturing the ultrasonic transducer 100 will be described.

[0031] Figures 4A(a) to 4B(e) are cross-sectional views showing a manufacturing method of the ultrasonic transducer 100. Figures 4A(a) to 4A(f) and 4B(a) to 4B(e) correspond to cross-sectional views taken along line A-A' in Figure 1(a). In Figures 4A(a) to 4B(e), the lower electrode 14 and the upper electrode 18 have a single-layer structure. 4A(a), an SOI substrate is prepared, which is composed of a silicon substrate 12a, a silicon oxide film 12b, and a silicon layer 12c. 4A(b), a layer of material that will become the thermal oxide film 13 is formed on the entire surface of the silicon layer 12c. The material layer that will become the thermal oxide film 13 is formed by, for example, sputtering or vacuum deposition. In this example, a silicon oxide film, for example, is formed as the material layer. 4A(c), an electrode material that will become the lower electrode 14 is formed on the entire surface of the thermal oxide film 13. The lower electrode 14 is formed by using, for example, sputtering or vacuum deposition. 4A(d), the piezoelectric layer 16 is formed on the entire surface of the lower electrode 14. The piezoelectric layer 16 is formed by, for example, sputtering or vacuum deposition. 4A(e), an electrode material that will become the upper electrode 18 is formed on the entire surface of the piezoelectric layer 16. The electrode material is formed by, for example, sputtering or vacuum deposition. As shown in FIG. 4A(f), the electrode material corresponding to the upper electrode 18 is patterned using, for example, photolithography and etching.

[0032] 4B(a), the entire surface is coated with photoresist. The photoresist is patterned, leaving portions corresponding to the frame 11, beams 17, and vibrating body 20. The photoresist is patterned so as to form an opening that exposes the lower electrode 14 in the portion surrounded by the frame 11, beams 17, and vibrating body 20.

[0033] 4B(b), the lower electrode 14 remains in the portion that will become the first gap 40a surrounded by the frame 11, the beam 17, and the vibrating body 20, so this portion of the lower electrode 14 is removed by etching. As a result, the lower electrode 14 and the piezoelectric layer 16 remain in the region that will become the frame 11, the beam 17, and the vibrating body 20. 4B(c), wiring 50 and electrode pads 52 and 54 are formed on the piezoelectric layer 16 of the frame 11. The wiring 50 and electrode pads 52 and 54 are formed by using, for example, sputtering or vacuum deposition. As shown in FIG. 4B(d), the silicon oxide film 12b, the silicon layer 12c, and the thermal oxide film 13 remain in the portion that will become the first gap 40a surrounded by the frame 11, the beam 17, and the vibrating body 20, and are therefore removed by DRIE from above. Subsequently, as shown in FIG. 4B(e), the silicon substrate 12a remains in the portion that will become the second gap 40b surrounded by the frame 11, and is therefore removed by DRIE from below, leaving behind the portion that will become the column 30. This completes the manufacturing process of the ultrasonic transducer 100. This manufacturing method is just one example, and any other manufacturing method may be used as long as it can realize the structure shown in Figures 1(a) to 1(c). [Performance comparison explanation] Next, the performance of the ultrasonic transducer 100 according to the first embodiment will be explained in comparison with an acoustic transducer according to the prior art.

[0034] 5 is a diagram showing a list of parameters for comparing and explaining the performance of the ultrasonic transducer 100 according to the first embodiment with the performance of an acoustic transducer according to the conventional technology. Note that the parameter values ​​in FIG. 5 are derived by the finite element method or numerical calculations. Hereinafter, the structure of the ultrasonic transducer 100 according to the present invention will be referred to as the "present structure," and the structure of the acoustic transducer according to the prior art will be referred to as the "conventional structure." 5, the membrane size is the length of one side of the entire membrane. The membrane area is the area of ​​the component that moves due to the piezoelectric effect when an AC voltage is applied. In the case of a conventional structure, it is the total area of ​​the parts excluding the fixed base ends of the multiple cantilevers, and in the case of this structure, it is the total area of ​​the multiple cantilevers 22.

[0035] Comparing the two, the membrane size of the conventional structure is "500 μm" and the membrane area is "968,170 μm 2 The membrane size of this structure is 290 μm, and the membrane area is 316,896 μm 2 In other words, the membrane size of this structure is about 3 / 5 of the size of the membrane in the conventional structure, and the membrane area is about 1 / 3 of the size of the membrane area in the conventional structure. In addition, in Figure 5, the resonant frequency is the resonant frequency of the piezoelectric layer. The resonant frequency of the conventional structure is 72.7 kHz, and the resonant frequency of this structure is 77.8 kHz. 5, the sound pressure level indicates the strength of the sound wave and is expressed in units of dB. The sound pressure level can be calculated using the following formula (1).

[0036]

number

[0037] The coupling coefficient of the conventional structure was 0.34%, while the coupling coefficient of the new structure was 0.41%. In other words, the coupling coefficient of the new structure is larger than that of the conventional structure, and the new structure has a higher efficiency in converting electrical energy into vibration energy, which has contributed to improving the sound pressure level per unit area.

[0038] In addition, in Fig. 5, the mechanical Q value (dimensionless) indicates the strength of vibration of the vibrator. However, in the mechanical Q value in Fig. 5, the mechanical loss is set only in the piezoelectric layer. The mechanical Q value of the conventional structure is 72, while the mechanical Q value of this structure is 90. In other words, the mechanical Q value of this structure is larger than that of the conventional structure, and the mechanical loss is smaller than that of the conventional structure.

[0039] 5, the capacitance [pF] is the capacitance formed by the upper electrode 18, the piezoelectric layer 16, and the lower electrode 14, and is a value indicating the size of the overlapping area of ​​the upper electrode 18, the piezoelectric layer 16, and the lower electrode 14. The larger this value, the greater the sound pressure per unit area. The capacitance of the conventional structure is 49.3 pF, while the capacitance of this structure is 5.7 pF. In other words, the capacitance of this structure is about 1 / 9 of that of the conventional structure.

[0040] In addition, in Figure 5, the normalized sound pressure is the sound pressure divided by the area, and if the normalized sound pressure of the conventional structure is set to a reference value of "1," the normalized sound pressure of this structure is "1.18." In other words, the sound pressure per unit area is greater for this structure than for the conventional structure.

[0041] Although not shown as a parameter in Figure 5, it can be inferred that the area of ​​the maximum vibration part when the cantilever beam 22 of this structure vibrates is larger than that of the cantilever beam of the conventional structure, which contributed to the improvement of sound pressure. Furthermore, the value of the coupling coefficient is larger than that of the conventional structure, which can be inferred to have contributed to the improvement of sound pressure. From this, it can be inferred that the maximum deformation amount and coupling coefficient contributed more to the improvement of sound pressure than the electrostatic capacitance, resulting in a result that exceeds that of the conventional structure. [Effects of the first embodiment]

[0042] As described above, the ultrasonic transducer 100 of the first embodiment comprises a substrate 10 having a frame 11 and a gap 40, a plurality of beams 17 connected at one end to the frame 11 of the substrate 10, and a vibrating body 20 including a lower electrode 14, an upper electrode 18, and a piezoelectric layer 16 sandwiched between the lower electrode 14 and the upper electrode 18, the vibrating body 20 having a core 21 connected to the other ends of the plurality of beams 17 and a plurality of cantilever beams 22 extending outward from the outer periphery of the core 21 other than the portion connected to the plurality of beams 17, and a cylinder 30 connected at one longitudinal end to the core 21 of the vibrating body 20 within the gap 40b and positioned away from the inner periphery 11h of the frame 11.

[0043] With this configuration, the cylinder 30 can suppress vibration of the core 21 of the vibrating body 20, thereby narrowing the area of ​​the vibrating portion. This can improve the directionality of ultrasonic waves generated by the vibration of the vibrating body 20. Furthermore, the presence of the cylinder 30 narrows the volume of the gap 40, restricting the propagation of sound waves and improving the directionality of the sound waves. In addition, a gap is formed between the vibrating body 20 and the inner peripheral surface 11h of the frame 11, keeping them out of contact with each other, thereby reducing the effect of air pressure on the resonance frequency. Moreover, the ultrasonic transducer 100 according to the first embodiment is configured such that the vibrating body 20 has a plurality of cantilevers 22 that are substantially fan-shaped and extend radially outward from the core 21 when viewed in a plan view. With this configuration, the cantilever beam 22 can be vibrated with the core 21 connected to the cylinder 30 as a fulcrum, so the area of ​​the vibrating part can be made larger than in the past, and the sound pressure can be improved.

[0044] The vibrating body 20 and the frame 11 of the substrate 10 are connected by a plurality of beams 17, and one end of each beam 17 is connected between two circumferentially adjacent cantilever beams 22 on the outer periphery of the core 21, and the other end is connected to the inner surface 11h of the frame 11, so that each cantilever beam 22 and each beam 17 are not in contact with each other.

[0045] With this configuration, the vibrating body 20 can be supported on the frame 11 by the multiple beams 17, and the multiple beams 17 do not interfere with the operation of the cantilever beams 22, allowing each cantilever beam 22 to stably vibrate. This makes it possible to stably transmit ultrasonic waves with a higher sound pressure than conventional methods. [Correspondence in the first embodiment] In the first embodiment, the lower electrode 14 corresponds to the first electrode, the upper electrode 18 corresponds to the second electrode, the piezoelectric layer 16 corresponds to the piezoelectric body, the beam 17 corresponds to the connector, and the cylinder 30 corresponds to the pillar. Second Embodiment Next, a second embodiment of the present invention will be described with reference to Fig. 6, which shows the second embodiment. 〔composition〕 FIG. 6(a) is a plan view of an ultrasonic transducer 100A according to the second embodiment, and FIG. 6(b) is a bottom view of FIG. 6(a). The second embodiment differs from the first embodiment in the number and size of the cantilevers and the number of beams. Hereinafter, the same components as those described in the first embodiment will be denoted by the same reference numerals and the description thereof will be omitted as appropriate, and only the parts that differ from the first embodiment will be described in detail. As shown in FIGS. 6(a) and 6(b), the ultrasonic transducer 100A includes a substrate 10, a beam 17A, a vibrating body 20A, a cylinder 30, wiring 50, and electrode pads 52 and .

[0046] The beam 17A is disposed on the -Y direction side of the core 21A, with one end on the +Y direction side connected to the core 21A and one end on the -Y direction side connected to the inner peripheral surface 11h of the frame 11. That is, the beam 17A is a single beam, unlike the first embodiment. The layered structure of the beam 17A and the members of each layer have the same structure and members as the beam 17 of the first embodiment. The vibrating body 20A includes an upper electrode 18A, a core portion 21A, and a cantilever beam 22A. The core portion 21A is a substantially cylindrical portion at the center of the vibrating body 20A, similar to the core portion 21 of the first embodiment.

[0047] The cantilever beam 22A is formed integrally with the core portion 21A and is provided so as to protrude radially outward from the remaining outer periphery portion other than the portion connecting the beam 17A to the core portion 21A. Specifically, when viewed in a plan view, the cantilever beam 22A is formed so as to surround the periphery of the core portion 21A other than the portion connecting to the beam 17A, and the entire portion including the core portion 21A has a substantially fan shape. The cantilever beam 22A has its fan apex connected to the outer circumferential surface of the core portion 21A, and extends radially outward into the first gap 40a with its arc side facing radially outward. A gap is formed between the arc-side end face of cantilever beam 22A and inner peripheral surface 11h of frame 11. In other words, the arc-side end face of cantilever beam 22A and inner peripheral surface 11h are not in contact with each other.

[0048] Upper electrode 18A is formed across the upper surface of core 21A, the upper surface of the apex-side end of cantilever 22A, and the upper surface of the end of beam 17A on the core 21A side. That is, upper electrode 18A has a substantially circular shape when viewed in a plan view, but has a notch at the radially outer end that was formed when beam 17A and cantilever 22A were formed. [Effects of the second embodiment]

[0049] As described above, in the ultrasonic transducer 100A according to the second embodiment, the vibrating body 20 and the frame 11 of the substrate 10 are connected by one beam 17A, and the vibrating body 20 is formed to surround the core 21A except for the part that connects to the beam 17A when viewed in a plane, and has one cantilever beam 22A such that the entire body including the core 21A is approximately fan-shaped. With this configuration, the size of the cantilever beam, which is the vibrating part of the vibrating body, can be increased, thereby improving the sound pressure. [Corresponding relationship in the second embodiment] In the second embodiment, the lower electrode 14 corresponds to the first electrode, the upper electrode 18A corresponds to the second electrode, the piezoelectric layer 16 corresponds to the piezoelectric body, the beam 17A corresponds to the connector, and the cylinder 30 corresponds to the pillar. Third Embodiment Next, a third embodiment of the present invention will be described with reference to Fig. 7, which shows the third embodiment. 〔composition〕 FIG. 7 is a diagram showing the configuration of an ultrasonic transducer 100B according to the third embodiment, where FIG. 7(a) is a plan view and FIG. 7(b) is a bottom view. The third embodiment differs from the first embodiment in that the thickness and shape of the multiple cantilevers are the same but the lengths are different. Hereinafter, the same components as those described in the first embodiment will be denoted by the same reference numerals and the description thereof will be omitted as appropriate, and only the parts that differ from the first embodiment will be described in detail. As shown in FIG. 7(a), the ultrasonic transducer 100B includes a substrate 10, a plurality of beams 17, a vibrating body 20B, a cylinder 30, wiring 50, and electrode pads 52 and . The vibrating body 20B includes an upper electrode 18, a core 21, and a plurality of cantilevers 22B.

[0050] In the example shown in FIGS. 7(a) and 7(b), the multiple cantilevers 22B are configured with four cantilevers 22B. The four cantilevers 22B are formed integrally with the core 21 and are generally fan-shaped when viewed in a plan view. Each cantilever 22B has a uniform thickness, its fan apex connected to the outer circumferential surface of the core 21, and extends radially outward with its arc-shaped side facing radially outward. The four cantilevers 22B are configured to have different lengths extending radially outward at the same central angle. That is, the four cantilevers 22B have different surface sizes when viewed in a plan view, and the size of the gap between the arc-side end and the inner circumferential surface 11h of the frame 11 is different. [Effects of the third embodiment]

[0051] As described above, the ultrasonic transducer 100B according to the third embodiment is configured such that the multiple cantilevers 22B have the same shape and thickness but different radial extension lengths. Here, since the resonant frequency is correlated with the length of the cantilevers 22B, by varying the length of each cantilever 22B, it is possible to resonate at multiple different frequencies. As a result, it is possible to manufacture an element with a wide frequency band. [Corresponding relationship in the third embodiment] In the third embodiment, the lower electrode 14 corresponds to the first electrode, the upper electrode 18 corresponds to the second electrode, the piezoelectric layer 16 corresponds to the piezoelectric body, the beam 17 corresponds to the connector, and the cylinder 30 corresponds to the pillar. [Fourth embodiment] Next, a fourth embodiment of the present invention will be described with reference to Fig. 8, which is a diagram showing the fourth embodiment. 〔composition〕 FIG. 8 is a diagram showing the configuration of an ultrasonic transducer 100C according to the fourth embodiment, where FIG. 8(a) is a plan view and FIG. 8(b) is a bottom view. The fourth embodiment differs from the first embodiment in that each of the multiple cantilevers has a substantially isosceles triangle shape. Hereinafter, the same components as those described in the first embodiment will be denoted by the same reference numerals and the description thereof will be omitted as appropriate, and only the parts that differ from the first embodiment will be described in detail. As shown in FIG. 8(a), the ultrasonic transducer 100C includes a substrate 10, a plurality of beams 17, a vibrating body 20C, a cylinder 30, wiring 50, and electrode pads 52 and . The vibrating body 20C includes an upper electrode 18, a core 21, and a plurality of cantilevers 22C.

[0052] In the example shown in Figures 8(a) and (b), the multiple cantilevers 22C are composed of four cantilevers 22C. The four cantilevers 22C are formed integrally with the core 21 and form a substantially isosceles triangle in plan view. The apex side of each cantilever 22C, sandwiched between two equal sides, is connected to the outer circumferential surface of the core 21, and the cantilever 22C extends into the first gap 40a with its base side facing radially outward. In the example shown in Figures 8(a) and (b), the four cantilevers 22C are each configured to have the same shape and size and are provided at equal intervals along the circumferential direction of the core 21. A gap is formed between the end faces on the base sides of the four cantilevers 22C and the inner peripheral surface 11h of the frame 11. In other words, the end faces on the base sides of the four cantilevers 22C and the inner peripheral surface 11h of the frame 11 are not in contact with each other. Furthermore, the four beams 17 and the four cantilevers 22C are not in contact with each other, and gaps are formed between the four beams 17 and the four cantilevers 22C. [Effects of the fourth embodiment] As described above, the ultrasonic transducer 100C according to the fourth embodiment has a configuration including a plurality of cantilevers 22C each having a substantially isosceles triangular shape that extends radially outward from the core 21 when viewed in a plan view. With this configuration, similar to the first embodiment, the cantilever 22C vibrates around the core 21 as a fulcrum, so that the cantilever 22C can be vibrated to a greater extent than in the past, thereby improving the sound pressure compared to the past. [Corresponding relationship in the fourth embodiment] In the fourth embodiment, the lower electrode 14 corresponds to the first electrode, the upper electrode 18 corresponds to the second electrode, the piezoelectric layer 16 corresponds to the piezoelectric body, the beam 17 corresponds to the connector, and the cylinder 30 corresponds to the pillar. Fifth Embodiment Next, a fifth embodiment of the present invention will be described with reference to Fig. 9, which shows the fifth embodiment. 〔composition〕 In the fifth embodiment, an electroacoustic device 200 using the ultrasonic transducer 100 of the first embodiment will be described. 9A and 9B are diagrams showing the configuration of an electroacoustic device 200 according to a fifth embodiment, with Fig. 9A being a side cross-sectional view and Fig. 9B being a plan view, and Fig. 9A corresponds to the cross-sectional view taken along line CC' in Fig. 9B. 9(a) and 9(b), the height direction of the electroacoustic device 200 is the Z direction, the width direction is the X direction, and the direction perpendicular to the Z direction and the X direction is the Y direction.

[0053] 9(a) and 9(b), the electroacoustic device 200 includes a rectangular box-shaped housing 210. The electroacoustic device 200 further includes an ultrasonic transducer 100, first and second electrode pads 212 and 214, and first and second wirings 216 and 218, all of which are disposed within the housing 210. The electroacoustic device 200 further includes a control unit 220, third and fourth electrode pads 222 and 224, and third and fourth wirings 226 and 228, all of which are disposed within the housing 210. An opening 230 that is circular in plan view is formed in the center of the surface of the housing 210 on the +Z direction side. The ultrasonic transducer 100 is fixed to the inner wall portion on the +Z direction side of the housing 210 in an orientation in which the end face of the cylinder 30 faces the +Z direction and the surface of the upper electrode 18 faces the -Z direction.

[0054] Specifically, the second surface 11b, which is the end surface of the frame 11 of the ultrasonic transducer 100 facing the +Z direction, is fixed to the inner wall portion on the +Z direction side of the housing 210. Specifically, the second surface 11b of the ultrasonic transducer 100 is fixed to the inner wall portion around the opening 230. At this time, the end surface on the +Z direction side of the cylinder 30 of the ultrasonic transducer 100 and the entirety of the multiple cantilevers 22 face the opening surface of the opening 230, and are fixed within the housing 210 so that the center of the opening 230 and the center of the cylinder 30 are concentric. That is, the opening 230 is configured to have a size that can contain the entire vibrating body 20. In the fifth embodiment, the cylinder 30 is not fixed to the housing 210. That is, the end of the cylinder 30 on the +Z direction side is a free end. The first and second electrode pads 212 and 214 are electrode pads for applying an AC voltage to the upper electrode 18 and the lower electrode 14 of the ultrasonic transducer 100 . The first and second wirings 216 and 218 are wirings for supplying the AC voltage applied to the first and second electrode pads 212 and 214 to the upper electrode 18 and the lower electrode 14 . That is, the upper electrode 18 is connected to the first electrode pad 212 via the first wiring 216 , and the lower electrode 14 is connected to the second electrode pad 214 via the second wiring 218 .

[0055] The control unit 220 controls the operation of the ultrasonic transducer 100. The control unit 220 is configured by, for example, an ASIC (Application Specific Integrated Circuit) or the like. The control unit 220 controls the ultrasonic wave emission operation of the ultrasonic transducer 100 by controlling the AC voltage applied to the upper electrode 18 and the lower electrode 14 of the ultrasonic transducer 100. The control unit 220 also performs demodulation processing of the signal received by the ultrasonic transducer 100. The third and fourth electrode pads 222 and 224 are electrode pads for supplying power to the control unit 220 for operation. The third and fourth wirings 226 and 228 are wirings for supplying the power supplied to the third and fourth electrode pads 222 and 224 to a + power supply terminal and a - power supply terminal (not shown) of the control unit 220, respectively. That is, the + power supply terminal is connected to the third electrode pad 222 via the third wiring 226 , and the − power supply terminal is connected to the fourth electrode pad 224 via the fourth wiring 228 .

[0056] With the above configuration, the electroacoustic device 200 vibrates the multiple cantilevers 22 by controlling the applied voltage value and frequency using the control unit 220. This allows ultrasonic waves to be emitted from the cylinder 30 side. The emitted ultrasonic waves are then released to the outside through the opening 230. [Effects of the fifth embodiment]

[0057] As described above, the electroacoustic device 200 according to the fifth embodiment includes a housing 210 having an opening 230, an ultrasonic transducer 100 disposed in the housing 210, and a control unit 220 that controls the operation of the ultrasonic transducer 100, also disposed in the housing 210. Furthermore, the opening 230 is configured to have a size that can accommodate the vibrating body 20 when viewed in a plan view. Furthermore, the ultrasonic transducer 100 is disposed in the housing 210 such that the end face of the cylinder 30 on the +Z direction side and the surface of the vibrating body 20 on the +Z direction side face the outside of the housing 210 through the opening 230.

[0058] With this configuration, it is possible to impart directionality to the ultrasonic waves by the opening diameter of the opening 230. Furthermore, the cylinder 30 narrows the area of ​​the vibrating portion, thereby improving the directionality of the ultrasonic waves, and therefore ultrasonic waves can be efficiently emitted within the range limited by the opening 230. [Corresponding relationship in the fifth embodiment] In the fifth embodiment, the lower electrode 14 corresponds to the first electrode, the upper electrode 18 corresponds to the second electrode, the piezoelectric layer 16 corresponds to the piezoelectric body, the beam 17 corresponds to the connector, and the cylinder 30 corresponds to the pillar. Sixth Embodiment Next, a sixth embodiment of the present invention will be described with reference to Fig. 10, which shows the sixth embodiment. 〔composition〕 Fig. 10 shows the configuration of an electroacoustic device 200A according to the sixth embodiment, with Fig. 10(a) being a side cross-sectional view and Fig. 10(b) being a plan view, Fig. 10(a) corresponds to the cross-sectional view taken along line DD' in Fig. 10(b). 10(a) and 10(b), the height direction of the electroacoustic device 200A is the Z direction, the width direction is the X direction, and the direction perpendicular to the Z direction and the X direction is the Y direction. The sixth embodiment differs from the fifth embodiment in that the cylinder 30 of the ultrasonic transducer 100 is supported by a housing 210. Hereinafter, the same components as those described in the fifth embodiment will be denoted by the same reference numerals and the description thereof will be omitted as appropriate, and only the parts that differ from the fifth embodiment will be described in detail. As shown in FIGS. 10(a) and 10(b), the electroacoustic device 200A has a configuration in which the housing 210 in the electroacoustic device 200 of the fifth embodiment is replaced with a housing 210A.

[0059] The housing 210A includes a pillar support portion 232 that is X-shaped when viewed from above and crosses the opening 230. Specifically, the pillar support portion 232 is configured such that two beams are crossed in an X shape when viewed from above to form four beam portions, and each beam portion has a width that is equal to or greater than the width of the beam 17 of the ultrasonic transducer 100 and does not cover the cantilever beam 22. The +Z side end of the column 30 of the ultrasonic transducer 100 is fixed, for example, by adhesive or the like, to the core part where the four beam parts of the surface of the column support part 232 on the -Z side intersect.

[0060] The pillar support part 232 is formed integrally with the inner periphery of the opening 230 of the housing 210, and the cylinder 30 is supported by the housing 210. Furthermore, from the gap part of the opening 230 where the pillar support part 232 is not present, the four cantilevers 22 of the ultrasonic transducer 100 face outward, and the pillar support part 232 hardly obstructs the progression of the ultrasonic waves. [Effects of the Sixth Embodiment] As described above, the electroacoustic device 200A according to the sixth embodiment is configured to include the column support portion 232 that supports the column 30 on the housing 210 without covering the multiple cantilevers 22 of the vibrating body 20. [Corresponding relationship in the sixth embodiment] In the sixth embodiment, the lower electrode 14 corresponds to the first electrode, the upper electrode 18 corresponds to the second electrode, the piezoelectric layer 16 corresponds to the piezoelectric body, the beam 17 corresponds to the connecting body, the multiple cantilever beams 22 correspond to the vibrating part, and the cylinder 30 corresponds to the pillar. [Modification] In the above embodiment, the cylindrical column 30 has been described as an example, but the configuration is not limited to this, and other shapes such as a rectangular parallelepiped, a prism, or a shape with varying thickness may also be used.

[0061] In the fourth embodiment and its modified examples, the cantilever beams 22C are shaped like an approximately isosceles triangle, but the cantilever beams 22C may be shaped like another triangle, such as an equilateral triangle or a triangle with different side lengths. In addition, the cantilever beams 22C are shaped like the same shape and size, but the cantilever beams 22C may be shaped like different sizes, as in the third embodiment. Furthermore, in the above embodiment and its modified examples, the number of beams is four or one, but the present invention is not limited to this configuration, and may be configured with two, three, five or more beams. In the above embodiment and its modified examples, when multiple beams are provided, one wire is formed on the beam and two electrode pads are formed on the first surface 11a of the frame 11. However, the present invention is not limited to this configuration. Other configurations may be used, such as a configuration in which multiple wires are provided or a configuration in which three or more electrode pads are provided. Furthermore, in the above embodiment and its modified examples, the shape of the cantilever is configured to be approximately fan-shaped or approximately triangular, but it is not limited to this configuration and may be other shapes, for example, approximately rectangular.

[0062] Furthermore, in the above embodiment and its modified examples, the configuration includes a gap 40 configured as a through hole, but this configuration is not limited to this, and the configuration may also include a non-through gap as long as the vibrating body 20 is configured to be vibrable. In the above embodiment and its modified examples, the upper electrode 18 is configured to have a diameter slightly larger than that of the cylinder 30 when viewed in plan, but this configuration is not limiting, and the upper electrode 18 may be configured to have a different size. For example, the upper electrode 18 may be configured to have a smaller diameter than the cylinder 30, or may be configured to have a smaller diameter than the exemplified diameter within the range of a diameter larger than that of the cylinder 30, or may be configured to have a larger diameter than the exemplified diameter. Furthermore, in the above fifth embodiment, a configuration in which the ultrasonic transducer 100 is mounted has been described as an example, but the present invention is not limited to this configuration. A configuration in which any one of the ultrasonic transducers 100A to 100C of the above second to fourth embodiments is mounted may also be used. Furthermore, the present invention is not limited to a configuration in which a single ultrasonic transducer is mounted, and a configuration in which a transducer array in which multiple ultrasonic transducers are arranged in an array may also be mounted. In the above embodiment and its modified examples, an example in which an ultrasonic transducer is manufactured using an SOI substrate has been described, but the present invention is not limited to this configuration. For example, other configurations may be used, such as a configuration in which a vibration auxiliary layer, a thermal oxidation layer, a lower electrode, a piezoelectric layer, and an upper electrode are stacked on a silicon substrate. In addition, in the above embodiment and its modified examples, the present invention has been described as being applied to an ultrasonic transducer, but the present invention is not limited to this configuration. For example, the present invention may be applied to an acoustic transducer that converts sound waves other than ultrasonic waves. [Explanation of symbols]

[0063] 100, 100A to 100C... ultrasonic transducer, 10... substrate, 11... frame, 11a... first surface, 11b... second surface, 11h... inner peripheral surface, 12... support substrate, 12a... silicon substrate, 12b... silicon oxide film, 12c... silicon layer, 13... thermal oxide film, 14... lower electrode, 14a... first metal film, 14b... second metal film, 16... piezoelectric layer, 17, 17A... beam, 18, 18A... upper electrode, 18a... third metal film, 18b... fourth metal film, 20, 20A to 20C... vibrating body, 21, 2 1A, 21C...core portion, 22, 22A to 22C...cantilever beam, 30...cylinder, 40...gap, 40a...first gap, 40b...second gap, 50...wiring, 52, 54...electrode pad, 200, 200A...electroacoustic device, 210, 210A...housing, 212...first electrode pad, 214...second electrode pad, 216...first wiring, 218...second wiring, 220...control unit, 222...third electrode pad, 224...fourth electrode pad, 226...third wiring, 228...fourth wiring, 230...opening, 232...pillar support portion

Claims

1. a substrate having an air gap; a connector connected to the substrate and provided above at least a portion of the gap; a vibrating body provided above at least a portion of the gap, the vibrating body including a first electrode, a second electrode, and a piezoelectric body sandwiched between the first electrode and the second electrode, the vibrating body having a core connected to the connector, and a cantilever beam extending outward from an outer periphery of the core other than the connection portion with the connector; a pillar extending in a longitudinal direction including one end and connected to the core portion at the one end; A piezoelectric transducer comprising:

2. In claim 1, The piezoelectric transducer has a plurality of cantilevers extending radially from the core when viewed in a plan view.

3. In claim 2, The cantilever is a piezoelectric transducer that has a substantially fan-shaped or substantially triangular shape when viewed in a plan view.

4. In claim 1, the vibrating body and the substrate are connected by one connector, The vibrating body is a piezoelectric transducer having a single cantilever beam that is formed to surround the core portion except for the portion that connects to the connector when viewed in a plane, and has an approximately fan-shaped shape including the core portion.

5. In claim 2, the vibrating body and the substrate are connected by a plurality of the connecting bodies, one end of each of the connecting bodies is connected between two cantilevers adjacent in the circumferential direction at the outer periphery of the core, and the other end is connected to the substrate; A piezoelectric transducer in which each of the cantilevers and each of the connecting bodies are in no contact with each other.

6. In claim 2, The plurality of cantilevers are piezoelectric transducers having the same thickness and shape but different radially extending lengths.

7. In claim 1, A piezoelectric transducer in which a line is formed on the connector, the line being wired from the electrode of the first electrode or the second electrode on the side opposite to the pillar side of the vibrating body to the substrate.

8. a housing having an opening; A piezoelectric transducer according to any one of claims 1 to 7, disposed within the housing; a control unit disposed in the housing and controlling the operation of the piezoelectric transducer; the opening is configured to have a size that can accommodate the vibrator when seen in a plan view, The piezoelectric transducer is disposed in the housing so that the other end of the pillar and the surface of the vibrating body facing the pillar face the outside of the housing through the opening.

9. In claim 8, An electroacoustic device comprising a pillar support portion that supports the pillar on the housing without covering a vibrating portion of the vibrator.

Images