Acoustic conversion device

Abstract

To improve sensitivity.SOLUTION: An acoustic conversion device 100 includes a fixed frame 10 and a cantilever 20 having one end which is a fixed end 22 fixed to the fixed frame 10 and the other end which is a free end 21, and extending from the fixed frame 10 to the inside of the fixed frame 10, the cantilever 20 has a plurality of detection regions 23 capable of detecting physical quantities and a non-detection region 24 which does not detect physical quantities, and the electrodes of the plurality of detection regions 23 are electrically connected in series.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an acoustic transducer. [Background technology]

[0002] For example, a piezoelectric element is known that includes a piezoelectric film having one end supported and the other end free, and a pair of electrodes disposed on either side of the piezoelectric film (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-140638 Summary of the Invention [Problem to be solved by the invention]

[0004] SUMMARY OF THE INVENTION An object of the present disclosure is to provide an acoustic transducer that can improve sensitivity, in which an acoustic transducer having a piezoelectric element is required. [Means for solving the problem]

[0005] The acoustic transducer according to the present disclosure comprises a fixed frame and a cantilever having one end fixed to the fixed frame and the other end free, the cantilever extending from the fixed frame to the inside of the fixed frame, the cantilever having a plurality of detection regions capable of detecting physical quantities and a non-detection region that does not detect physical quantities, and the electrodes of the plurality of detection regions are electrically connected in series. [Effects of the Invention]

[0006] The present disclosure can provide an acoustic transducer capable of improving sensitivity. [Brief explanation of the drawings]

[0007] [Figure 1]1 is a plan view illustrating an acoustic transducer according to a first embodiment. [Figure 2] 1 is a cross-sectional view illustrating an acoustic transducer according to a first embodiment, taken along an XZ plane. FIG. [Figure 3] 1 is a cross-sectional view illustrating an acoustic transducer according to a first embodiment, taken along a YZ plane. [Figure 4] 1 is a circuit diagram of an acoustic transducer according to an embodiment. [Figure 5] FIG. 10 is a cross-sectional view illustrating an acoustic transducer according to a second embodiment, taken along the YZ plane. [Figure 6] FIG. 11 is a cross-sectional view illustrating an acoustic transducer according to a third embodiment, taken along the YZ plane. [Figure 7] FIG. 10 is a partial plan view illustrating a portion of the acoustic transducer according to the fourth embodiment. [Figure 8] FIG. 10 is a partially enlarged plan view illustrating an example of an acoustic transducer according to a fourth embodiment. [Figure 9] 9 is a cross-sectional view illustrating a cross section taken along line IX-IX in FIG. 7. [Figure 10] 9 is a cross-sectional view illustrating a cross section taken along line XX in FIG. 8. [Figure 11] FIG. 2 is a partially enlarged perspective view illustrating an example of an acoustic transducer. [Figure 12] FIG. 10 is a plan view illustrating an acoustic transducer according to a fifth embodiment. [Figure 13] FIG. 10 is a perspective view illustrating an acoustic transducer according to a fifth embodiment. [Figure 14] FIG. 11 is a perspective view illustrating an acoustic transducer according to a fifth embodiment, viewed from the bottom side. [Figure 15] FIG. 10 is a cross-sectional view illustrating an acoustic transducer according to a fifth embodiment. [Figure 16] FIG. 2 is a partially enlarged cross-sectional view illustrating an enlarged example of a diaphragm (piezoelectric film). [Figure 17] 10A and 10B are side views illustrating the distribution of electric charges generated on a diaphragm that is deformed by receiving sound pressure. [Figure 18]FIG. 10 is a plan view illustrating an acoustic transducer according to a sixth embodiment. [Figure 19] 19 is a cross-sectional view illustrating an acoustic transducer according to a sixth embodiment, taken along line IX-IX in FIG. 18. FIG. [Figure 20] FIG. 10 is a circuit diagram of an acoustic transducer according to a sixth embodiment. [Figure 21] 10 is a graph showing the relationship between the sensing area diameter ratio and the normalized SNR. DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, an acoustic transducer according to an embodiment will be described with reference to the accompanying drawings. In this specification and the drawings, substantially identical components may be designated by the same reference numerals to avoid redundant description. In addition, in this specification, the terms "upper" and "lower" may be used. These refer to the "upper" and "lower" in the state shown in FIG. 2, and in the Z-axis direction, the side where the upper electrode 30 is located is referred to as "upper" and the side where the lower electrode 40 is located is referred to as "lower". The actual arrangement of the acoustic transducer 100 is not limited to this. The upper electrode 30 may be located at the bottom, and the lower electrode 40 may be located at the top.

[0009] [Sound transducer 100 according to the first embodiment] FIG. 1 is a perspective view illustrating an acoustic transducer 100 according to the first embodiment. FIG. 2 is a cross-sectional view illustrating the acoustic transducer 100 according to the first embodiment, showing a cross section along the XZ plane. Note that in each drawing, the X-axis direction, the Y-axis direction, and the Z-axis direction, which are orthogonal to each other, may be illustrated. The X-axis direction, the Y-axis direction, and the Z-axis direction do not have to be orthogonal to each other. The X-axis direction, the Y-axis direction, and the Z-axis direction may be any direction. The X-axis direction is an example of a first direction. The Y-axis direction is an example of a second direction intersecting with the first direction. The Z-axis direction is an example of the thickness direction of the piezoelectric film.

[0010] The acoustic transducer 100 shown in FIGS. 1 and 2 is a piezoelectric acoustic transducer having a piezoelectric element (piezoelectric film). The acoustic transducer 100 may be, for example, a microphone (MEMS microphone). The acoustic transducer 100 may be used for noise cancellation purposes. The acoustic transducer 100 may be a TWS (Ture wireless stereo) or an in-vehicle device installed in an automobile. The acoustic transducer 100 may be used, for example, as a hearing aid. The acoustic transducer 100 may be any device capable of detecting a physical quantity, and its use is not particularly limited. The physical quantity may be, for example, sound pressure.

[0011] [Fixed Frame 10] The acoustic transducer 100 includes a fixed frame 10 and a pair of cantilevers 20. The fixed frame 10 is a rectangular frame when viewed in the Z-axis direction. The length of the fixed frame 10 in the X-axis direction is shorter than the length of the fixed frame 10 in the Y-axis direction. The fixed frame 10 has a first base 11 and a second base 12. The first base 11 may be a substrate. The second base 12 is formed on the first base 11.

[0012] [Cantilever 20] The pair of cantilevers 20 each have a piezoelectric film. The cantilevers 20 extend in the X-axis direction from the fixed frame 10 to the inside of the fixed frame 10. One end of the cantilever 20 is a fixed end 22, and the other end is a free end 21.

[0013] The pair of cantilevers 20 includes cantilevers 20A and 20B arranged opposite each other in the X-axis direction. The cantilever 20A is an example of a first cantilever, and the cantilever 20B is an example of a second cantilever. The free ends 21 of the pair of cantilevers 20 face each other.

[0014] As shown in FIG. 1, a pair of slits 71 and 72 are formed around the cantilevers 20A and 20B. The slits 71 and 72 are gaps formed between the fixing frame 10 and the cantilever 20, and penetrate the substrate in the Z-axis direction. The pair of slits 71 extend in the X-axis direction and are spaced apart in the Y-axis direction. The slit 72 is a gap formed between the free end 21 and the fixing frame 10. The fixed end 22 of the cantilever 20 is connected to the fixing frame 10. The width of the slits 71 and 72 may be, for example, 100 nm or more and 5 μm or less. The width of the slits 71 and 72 may be, for example, 0.5 μm.

[0015] 2 shows a cross section along the XZ plane of the cantilever 20 (20A) and the fixed frame 10. The piezoelectric film of the cantilever 20 has a lower electrode 40, a lower piezoelectric layer 61, an intermediate electrode 50, an upper piezoelectric layer 62, and an upper electrode 30, as shown in FIG.

[0016] [Lower electrode 40] The lower electrode 40 is a thin electrode film and includes a lower electrode 41 and a lower electrode 42. The lower electrode 41 and the lower electrode 42 are spaced apart in the X-axis direction. Between the lower electrode 41 and the lower electrode 42, there is an electrode-free region 82 where no electrode is formed. After the lower electrode 40 is formed, etching is performed to remove the electrode, thereby forming the electrode-free region 82. The electrode-free region 82 may be formed using a lift-off method.

[0017] The lower electrode 41 is formed closer to the fixed end 22 in the X-axis direction. The lower electrode 42 is formed closer to the free end 21 in the X-axis direction.

[0018] [Lower piezoelectric layer 61] The lower piezoelectric layer 61 is a piezoelectric thin film, and is formed on the lower electrode 40. The lower piezoelectric layer 61 is formed continuously in the X-axis direction.

[0019] [Intermediate electrode 50] The intermediate electrode 50 is a thin electrode film and includes an intermediate electrode 51 and an intermediate electrode 52. The intermediate electrodes 51 and 52 are spaced apart in the X-axis direction. Between the intermediate electrodes 51 and 52, there is an electrode-free region 83 where no electrode is formed. After the intermediate electrode 50 is formed, etching is performed to remove the electrode, thereby forming the electrode-free region 83. The electrode-free region 83 may be formed using a lift-off method.

[0020] The intermediate electrode 51 is formed closer to the fixed end 22 in the X-axis direction. The intermediate electrode 52 is formed closer to the free end 21 in the X-axis direction.

[0021] [Upper piezoelectric layer 62] The upper piezoelectric layer 62 is a piezoelectric thin film, and is formed on the intermediate electrode 50. The upper piezoelectric layer 62 is formed continuously in the X-axis direction.

[0022] [Top electrode 30] The upper electrode 30 is a thin electrode film and includes an upper electrode 31 and an upper electrode 32. The upper electrode 31 and the upper electrode 32 are spaced apart in the X-axis direction. Between the upper electrode 31 and the upper electrode 32, there is an electrode-free region 81 where no electrode is formed. After the upper electrode 30 is formed, etching is performed to remove the electrode, thereby forming the electrode-free region 81. The electrode-free region 81 may be formed using a lift-off method.

[0023] The upper electrode 31 is formed closer to the fixed end 22 in the X-axis direction. The upper electrode 32 is formed closer to the free end 21 in the X-axis direction.

[0024] [Material and thickness of piezoelectric thin film] The material of the lower piezoelectric layer 61 and the upper piezoelectric layer 62 may be, for example, ScAlN. The material of the lower piezoelectric layer 61 may be AlN. Sc may be 0 at % or more and 50 at % or less. The thickness of the lower piezoelectric layer 61 and the upper piezoelectric layer 62 may be, for example, 100 nm or more and 1 μm or less. The thickness of the lower piezoelectric layer 61 and the upper piezoelectric layer 62 may be, for example, 500 nm.

[0025] The lower piezoelectric layer 61 and the upper piezoelectric layer 62 may have a fluorite structure (hafnium oxide, zirconium oxide, cesium oxide) or a wurtzite structure (zinc oxide).

[0026] [Electrode thin film material and thickness] The upper electrode 30, the lower electrode 40, and the intermediate electrode 50 may be made of materials such as Al, Mo, Pt, or Ti. The thickness of the upper electrode 30, the lower electrode 40, and the intermediate electrode 50 may be, for example, 5 nm or more and 100 nm or less. The thickness of the upper electrode 30, the lower electrode 40, and the intermediate electrode 50 may be, for example, 50 nm.

[0027] [Detection area 23 and non-detection area 24] The cantilever 20 has a plurality of detection regions 23 capable of detecting a physical quantity, and a non-detection region 24 that does not detect a physical quantity. The physical quantity is, for example, sound pressure. The plurality of detection regions 23 may be regions in which the upper electrode 31, the intermediate electrode 51, and the lower electrode 41 are arranged overlapping each other in the Z-axis direction. The upper electrode 31, the intermediate electrode 51, and the lower electrode 41 are electrically connected. The acoustic transducer 100 can detect a piezoelectric output charge between the upper electrode 31 and the intermediate electrode 51. The acoustic transducer 100 can detect a piezoelectric output charge between the lower electrode 41 and the intermediate electrode 51.

[0028] The detection area 23 is disposed closer to the fixed end 22 than the non-detection area 24. In other words, the non-detection area 24 is disposed closer to the free end 21 than the detection area 23.

[0029] The upper electrode 32, the intermediate electrode 52, and the lower electrode 42 are not electrically connected.

[0030] [Multiple detection areas 23] 3 is a cross-sectional view illustrating the acoustic transducer 100 according to the first embodiment, showing a cross section along the YZ plane. As shown in Fig. 3, the acoustic transducer 100 has a plurality of detection areas 23 arranged in the Y-axis direction. Each of the plurality of detection areas 23 has an upper electrode 31 (upper electrode 31A), a lower electrode 41 (lower electrode 41A), an intermediate electrode 51 (intermediate electrode 51A), a lower piezoelectric layer 61 (lower piezoelectric layer 61A), and an upper piezoelectric layer 62 (upper piezoelectric layer 62A).

[0031] A non-detection region 25 is formed between adjacent detection regions 23 in the Y-axis direction. The non-detection region 25 is a region where no physical quantity is detected. A piezoelectric layer is formed in the non-detection region 25. The piezoelectric layer of the non-detection region 25 is formed integrally with the lower piezoelectric layer 61 and the upper piezoelectric layer 62. The non-detection region 25 is an example of a first electrode-free region where the upper electrode 31 and the lower electrode 41 are not formed. The non-detection region 25 is also an example of a second electrode-free region where the intermediate electrode 51 is not formed.

[0032] [Circuit diagram of the acoustic transducer 100 according to the embodiment] Next, a circuit diagram of the sound transducer 100 according to the embodiment will be described. Fig. 4 is a circuit diagram of the sound transducer 100 according to the embodiment.

[0033] As shown in FIG. 4, the acoustic transducer 100 includes a MEMS microphone chip 101. The MEMS microphone chip 101 includes a pair of cantilevers 20A and 20B. The MEMS microphone chip 101 may include three or more cantilevers 20. The cantilevers 20A and 20B include a plurality of detection regions 23. The plurality of detection regions 23 includes an upper electrode 31, a lower electrode 41, and an intermediate electrode 51. The acoustic transducer 100 can detect a piezoelectric output charge between the upper electrode 31 and the intermediate electrode 51, and a piezoelectric output charge between the lower electrode 41 and the intermediate electrode 51. The plurality of cantilevers 20A and 20B are connected in series. In the cantilever 20A, the plurality of detection regions 23 are connected in series. In the cantilever 20B, the plurality of detection regions 23 are connected in series. The plurality of detection regions 23 of the cantilever 20A and the plurality of detection regions 23 of the cantilever 20B are connected in series.

[0034] The MEMS microphone chip 101 also has pads 13 and 14. A cantilever 20A is connected to the pad 13, and a cantilever 20B is connected to the pad 14. The acoustic transducer 100 includes an IC 102 connected to the pad 13. The IC 102 is an amplifier that amplifies the output signal of the cantilever 20. The IC 102 may be provided with a function to perform AD (analog-to-digital) conversion after amplifying the output signal of the cantilever 20.

[0035] [Wiring section 16] Fig. 11 is a partially enlarged perspective view illustrating an example of a portion of the acoustic transducer 100. As shown in Figs. 1, 4, and 11, the acoustic transducer 100 includes a wiring section 16 that electrically connects the multiple detection areas 23 and the pads 13, 14. The wiring section 16 may be formed, for example, on the upper surface (front surface) of the fixed frame 10. A portion of the wiring section 16 may be formed inside the fixed frame 10. The wiring section 16 connects the electrodes of the multiple detection areas 23 in series.

[0036] 11, the wiring portion 16 includes wiring portions 16a, 16b, 16c, 16d, and 16e. The wiring portion 16a electrically connects the intermediate electrode 51 and the pad 13. The wiring portion 16a is drawn out from the intermediate electrode 51 and connected to the pad 13.

[0037] Wiring portion 16b, which is drawn from upper electrode 31 toward fixed frame 10, is electrically connected to wiring portion 16c, which is drawn from lower electrode 41 toward fixed frame 10. Wiring portion 16b and wiring portion 16c are connected on fixed frame 10. Wiring portion 16d is connected to wiring portion 16b.

[0038] The wiring portion 16d drawn out from the upper electrode 31 is connected on the fixed frame 10 to the wiring portion 16e drawn out from the intermediate electrode 51 toward the fixed frame 10 side.

[0039] 1, the wiring portion 16 includes a wiring portion 16f. The wiring portion 16f is drawn out from the upper electrode 31 toward the fixing frame 10 and is connected to a pad 14 on the fixing frame 10.

[0040] [Shape of cantilever 20] As described above, the shape of the cantilever 20 is rectangular when viewed in the Z-axis direction. When the cantilever 20 is rectangular, the area of ​​the cantilever 20 within the chip can be increased, making it possible to increase the sensitivity of the cantilever 20. In other words, for the same sensitivity, the acoustic transducer 100 can be made smaller than conventional devices. The acoustic transducer 100 can be made smaller and less expensive.

[0041] [Total length of cantilever 20] In the acoustic transducer 100, the resonant frequency of the cantilever 20 can be easily changed by changing the overall length of the cantilever 20. At the time of design, the resonant frequency can be lowered by increasing the overall length of the cantilever 20. The resonant frequency when the overall length of the cantilever 20 is long is lower than the resonant frequency when the overall length of the cantilever 20 is short. The overall length of the cantilever 20 may be the length of the region where the upper electrode 30, the lower electrode 40, and the intermediate electrode 50 overlap.

[0042] [Cantilever 20 width] The width of the cantilever 20 is the width along the Y-axis direction. The width of the cantilever 20 may be the width of the area where the upper electrode 30, the lower electrode 40, and the intermediate electrode 50 overlap. In the acoustic transducer 100, the sensitivity of the cantilever 20 can be changed regardless of the resonant frequency by changing the width of the cantilever 20. At the time of design, the sensitivity can be increased by increasing the width of the cantilever 20. The sensitivity when the cantilever 20 is wide is higher than when the width is narrow.

[0043] [Actions and Effects of the Sound Converter 100 According to the First Embodiment] The acoustic transducer 100 according to the first embodiment includes a fixed frame 10 and a cantilever 20 having one end that is a fixed end 22 fixed to the fixed frame 10 and the other end that is a free end 21, the cantilever 20 extending from the fixed frame 10 to the inside of the fixed frame 10, the cantilever 20 having a plurality of detection regions 23 that can detect a physical quantity and a non-detection region 24 that does not detect a physical quantity, and the electrodes of the plurality of detection regions 23 are electrically connected in series.

[0044] In the acoustic transducer 100 of this embodiment, the cantilever 20 deforms, and the deformation of the cantilever 20 is detected, thereby detecting a physical quantity. In the acoustic transducer 100, a plurality of detection areas 23 are formed, and the electrodes of these plurality of detection areas 23 are electrically connected in series, thereby improving the sensitivity of the cantilever 20.

[0045] In the acoustic transducer 100, the piezoelectric film of the cantilever 20 can be divided at any plane and electrically connected in series, thereby allowing the capacitance of the entire piezoelectric film (total of the multiple detection areas 23) to be adjusted as desired.

[0046] In the acoustic transducer 100, the electrodes are separated in the width direction (Y-axis direction) of the cantilever 20, thereby forming a plurality of detection regions, thereby improving sensitivity.

[0047] Furthermore, in the acoustic transducer 100, the electrodes are divided in the length direction (X-axis direction) of the cantilever 20, thereby forming a detection region 23 and a non-detection region 24, thereby improving sensitivity.

[0048] The cantilever 20 has a cantilever (first cantilever) 20A and a cantilever (second cantilever) 20B that face each other in the X-axis direction (first direction), which is the direction in which the cantilever 20 projects. According to the acoustic transducer 100 having this configuration, the sensitivity of the cantilever 20 can be improved.

[0049] In the acoustic transducer 100 according to the embodiment, the electrodes of the plurality of detection regions 23 of the cantilever 20A and the electrodes of the plurality of detection regions 23 of the cantilever 20B are electrically connected in series. According to the acoustic transducer 100 having this configuration, the sensitivity of the cantilever 20 can be improved.

[0050] Furthermore, in the acoustic transducer 100 according to the embodiment, the multiple detection regions 23 are arranged closer to the fixed end 22, and the non-detection regions 24 are arranged closer to the free end 21. The acoustic transducer 100 having this configuration can improve the sensitivity of the cantilever 20. In the cantilever 20, stress concentrates at the base portion near the first base 11 on the fixed end 22 side, generating a large amount of charge. On the other hand, almost no stress occurs on the free end 21 side of the cantilever 20, generating little charge. Therefore, by electrically isolating the base portion of the first base 11 on the fixed end 22 side from the tip portion on the free end 21 side and using only the base portion as the detection region 23, the charge generated per unit area can be improved. This improves the signal level, thereby improving sensitivity.

[0051] In addition, in the acoustic transducer 100, the cantilever 20 has a piezoelectric film, which includes a lower electrode 40, a lower piezoelectric layer 61 formed on the lower electrode 40, an intermediate electrode 50 formed on the lower piezoelectric layer 61, an upper piezoelectric layer 62 formed on the intermediate electrode 50, and an upper electrode 30 formed on the upper piezoelectric layer 62, and has a non-detection region (first electrode non-forming region or second electrode non-forming region) 25 between multiple detection regions 23.

[0052] In the acoustic transducer 100 having this configuration, the cantilever 20, which is a piezoelectric film, is deformed, and piezoelectric output charges generated between the upper electrode 31 and the intermediate electrode 51 and between the lower electrode 41 and the intermediate electrode 51 in the multiple detection areas 23 are connected to the intermediate electrode 51. The multiple detection areas 23 can be divided by forming non-detection areas (electrode-free areas) 25 where the upper electrode 30, the lower electrode 40, and the intermediate electrode 50 are not formed.

[0053] Furthermore, in the acoustic transducer 100, the electrode-free region 82 where the lower electrode 40 is not formed is located farther from the fixed end 22 than the electrode-free region 81 where the upper electrode 30 is not formed. This makes it possible to avoid a decrease in the crystallinity of the lower piezoelectric layer 61 between the lower electrode 41 and the intermediate electrode 51, and the crystallinity of the upper piezoelectric layer 62 between the intermediate electrode 51 and the upper electrode 31. Therefore, electric charges can be generated stably in the lower piezoelectric layer 61 and the upper piezoelectric layer 62.

[0054] Furthermore, the acoustic transducer 100 is a piezoelectric acoustic transducer, and is more resistant to dust and water droplets than conventional electrostatic acoustic transducers.

[0055] Furthermore, because the acoustic transducer 100 has a rectangular shape, the area of ​​the cantilever 20 within the chip can be increased, enabling higher sensitivity. Since the acoustic transducer 100 can achieve high sensitivity, it can be made smaller. In the acoustic transducer 100, the resonant frequency can be easily changed by changing the length of the detection region 23 of the cantilever 20. In the acoustic transducer 100, the sensitivity can be changed regardless of the resonant frequency by changing the width W20 of the detection region 23.

[0056] [Sound transducer 100B according to the second embodiment] Next, an acoustic transducer 100B according to a second embodiment will be described. FIG. 5 is a cross-sectional view illustrating the acoustic transducer 100B according to the second embodiment, showing a cross section along the YZ plane. The acoustic transducer 100B according to the second embodiment shown in FIG. 5 differs from the acoustic transducer 100 according to the first embodiment shown in FIG. 3 in that non-detection regions 25A and 25B are formed instead of the non-detection region 25, and in that the arrangements of the upper electrode 31, the lower electrode 41, and the intermediate electrode 51 are different. Note that, in the description of the acoustic transducer 100B according to the second embodiment, descriptions that are the same as those of the acoustic transducer 100 according to the first embodiment may be omitted.

[0057] [Non-detection areas 25A and 25B] The cantilever 20 of the acoustic transducer 100B has a plurality of detection areas 23A, 23B, 23C, and 23D. These plurality of detection areas 23A, 23B, 23C, and 23D are arranged side by side in the Y-axis direction. A non-detection area 25A is formed between the detection area 23A and the detection area 23B. A non-detection area 25B is formed between the detection area 23B and the detection area 23C. A non-detection area 25A is formed between the detection area 23C and the detection area 23D.

[0058] The intermediate electrode 51 in the detection region 23A is electrically connected to the intermediate electrode 51 in the detection region 23B. The upper electrode 31 in the detection region 23A is not electrically connected to the upper electrode 31 in the detection region 23B. The lower electrode 41 in the detection region 23A is not electrically connected to the lower electrode 41 in the detection region 23B. An intermediate electrode 51 that connects the detection regions 23A and 23B in series is formed in the non-detection region 25A. The non-detection region 25A is an example of a first electrode-free region in which the upper electrode 31 and the lower electrode 41 are not formed.

[0059] The upper electrode 31 of the detection region 23B is electrically connected to the upper electrode 31 of the detection region 23C. The lower electrode 41 of the detection region 23B is electrically connected to the lower electrode 41 of the detection region 23C. The intermediate electrode 51 of the detection region 23B is not electrically connected to the intermediate electrode 51 of the detection region 23C. In the non-detection region 25B, an upper electrode 31 and a lower electrode 41 are formed which connect the detection regions 23B and 23C in series. The non-detection region 25B is an example of a second electrode non-formation region in which the intermediate electrode 51 is not formed.

[0060] The intermediate electrode 51 in the detection region 23C is electrically connected to the intermediate electrode 51 in the detection region 23D. The upper electrode 31 in the detection region 23C is not electrically connected to the upper electrode 31 in the detection region 23D. The lower electrode 41 in the detection region 23C is not electrically connected to the lower electrode 41 in the detection region 23D. An intermediate electrode 51 that connects the detection regions 23C and 23D in series is formed in the non-detection region 25A. The non-detection region 25A is an example of a first electrode-non-formation region in which the upper electrode 31 and the lower electrode 41 are not formed.

[0061] In the sound transducer 100B, the non-detection areas 25A and the non-detection areas 25B are arranged alternately in the Y-axis direction.

[0062] [Polarization direction of the piezoelectric film of cantilever 20] Next, the polarization direction of the piezoelectric film of the cantilever 20 will be described. In FIG. 5, the polarization directions in the lower piezoelectric layer 61 and the upper piezoelectric layer 62 are connected by arrows. For example, terminal B (pad 13) is electrically connected to the upper electrode 31 and the lower electrode 41 in the detection area 23A, and terminal A (pad 14) is electrically connected to the upper electrode 31 and the lower electrode 41 in the detection area 23D. Note that other electrodes and wiring portions may be electrically connected between the upper electrode 31 and the lower electrode 41 and terminals A and B. For example, terminal B is set to GND. For example, if an arbitrary value is "x", the potentials of the electrodes (upper electrode 31, lower electrode 41, and intermediate electrode 51) between terminals A and B have the following relationship, and a series connection is realized:

[0063] The potential of the upper electrode 31 and the lower electrode 41 in the detection region 23D may be +4xV. The potential of the intermediate electrode 51 in the detection region 23D and the detection region 23C may be +3xV. The potential of the upper electrode 31 and the lower electrode 41 in the detection region 23C and the detection region 23B may be +2xV. The potential of the intermediate electrode 51 in the detection region 23B and the detection region 23A may be +xV. The potential of the upper electrode 31 and the lower electrode 41 in the detection region 23A may be 0V.

[0064] The polarization direction in detection region 23A is the direction from the upper electrode 31 and the lower electrode 41 toward the intermediate electrode 51. The polarization direction in detection region 23B is the direction from the intermediate electrode 51 toward the upper electrode 31 and the lower electrode 41. The polarization direction in detection region 23C is the direction from the upper electrode 31 and the lower electrode 41 toward the intermediate electrode 51. The polarization direction in detection region 23D is the direction from the intermediate electrode 51 toward the upper electrode 31 and the lower electrode 41.

[0065] By applying a DC (direct current) voltage between terminal A and terminal B in advance, the polarization direction of the piezoelectric film can be realized as described above.

[0066] [Actions and Effects of the Sound Converter 100B According to the Second Embodiment] The sound transducer 100B according to the second embodiment also has the same effects as the sound transducer 100 according to the first embodiment. In the sound transducer 100B according to the second embodiment, the non-detection areas 25A and the non-detection areas 25B may be arranged alternately.

[0067] In the acoustic transducer 100B having this configuration, it is not necessary to form the wiring section 16 independently, and the multiple detection regions (divided regions) 23 can be electrically connected in series. The fact that it is not necessary to form the wiring section 16 independently means that it is not necessary to form a wiring section outside the piezoelectric film as a wiring section that connects the multiple detection regions 23. In the acoustic transducer 100, the series connection can be achieved by making the polarization directions of adjacent regions in the multiple detection regions 23 of the piezoelectric film different from each other.

[0068] The acoustic transducer 100B does not require an external wiring section 16 connecting multiple detection regions 23, thereby saving space, reducing the complexity of the film formation process, and suppressing unintended increases in the capacitance of the entire device due to parasitic capacitance and leakage current. The acoustic transducer 100B can reduce the number of wiring sections 16 formed on the upper surface of the fixed frame 10, thereby saving space and reducing the size of the acoustic transducer 100B. For example, compared to conventional acoustic transducers, if the area of ​​the acoustic transducer 100B is kept the same, the sensitivity may be improved by increasing the area of ​​the piezoelectric film of the cantilever 20.

[0069] [Sound transducer 100C according to the third embodiment] Next, an acoustic transducer 100C according to a third embodiment will be described. FIG. 6 is a cross-sectional view illustrating the acoustic transducer 100C according to the third embodiment, showing a cross section along the YZ plane. The acoustic transducer 100C shown in FIG. 6 differs from the acoustic transducer 100 according to the first embodiment shown in FIG. 3 in that a non-detection region 25C is formed instead of the non-detection region 25, and that a lower connection electrode 53 and an upper connection electrode 54 are formed. Note that, in the description of the acoustic transducer 100C according to the third embodiment, explanations similar to those of the acoustic transducers 100 and 100B according to the above embodiments may be omitted.

[0070] [Non-detection areas 25A and 25B] The cantilever 20 of the acoustic transducer 100C has a plurality of detection regions 23A, 23B, 23C, and 23D. These plurality of detection regions 23A, 23B, 23C, and 23D are arranged side by side in the Y-axis direction. A non-detection region 25C is formed between the detection region 23A and the detection region 23B. Similarly, a non-detection region 25C is formed between the detection region 23B and the detection region 23C. A non-detection region 25C is formed between the detection region 23C and the detection region 23D. The detection regions 23A and 23C are examples of first detection regions, and the detection regions 23B and 23D are examples of second detection regions.

[0071] A lower connection electrode 53 and an upper connection electrode 54 are formed in the non-detection region 25C between the detection region 23A and the detection region 23B. The lower connection electrode 53 electrically connects the lower electrode 41 (first lower electrode 41A) in the detection region 23A to the intermediate electrode 51 (second intermediate electrode 51B) in the detection region 23B. The upper connection electrode 54 electrically connects the upper electrode 31 (first upper electrode 31A) in the detection region 23A to the intermediate electrode 51 in the detection region 23B. The lower connection electrode 53 and the upper connection electrode 54 are formed so as to branch off from the intermediate electrode 51 in the detection region 23B. The intermediate electrode 51 (first intermediate electrode 51A) in the detection region 23A is not connected to the upper electrode 31 (second upper electrode 31B), lower electrode 41 (second lower electrode 41B), and intermediate electrode 51 (second intermediate electrode 51B) in the detection region 23B.

[0072] A lower connection electrode 53 and an upper connection electrode 54 are formed in the non-detection region 25C between the detection region 23B and the detection region 23C. The lower connection electrode 53 electrically connects the lower electrode 41 in the detection region 23B to the intermediate electrode 51 in the detection region 23C. The upper connection electrode 54 electrically connects the upper electrode 31 in the detection region 23B to the intermediate electrode 51 in the detection region 23C. The lower connection electrode 53 and the upper connection electrode 54 are formed so as to branch off from the intermediate electrode 51 in the detection region 23C. The intermediate electrode 51 in the detection region 23B is not connected to the upper electrode 31, lower electrode 41, and intermediate electrode 51 in the detection region 23C.

[0073] A lower connection electrode 53 and an upper connection electrode 54 are formed in the non-detection region 25C between the detection region 23C and the detection region 23D. The lower connection electrode 53 electrically connects the lower electrode 41 of the detection region 23C to the intermediate electrode 51 of the detection region 23D. The upper connection electrode 54 electrically connects the upper electrode 31 of the detection region 23C to the intermediate electrode 51 of the detection region 23D. The lower connection electrode 53 and the upper connection electrode 54 are formed so as to branch off from the intermediate electrode 51 of the detection region 23D. The intermediate electrode 51 of the detection region 23C is not connected to the upper electrode 31, lower electrode 41, and intermediate electrode 51 of the detection region 23D.

[0074] [Polarization direction of the piezoelectric film of cantilever 20] Next, the polarization direction of the piezoelectric film of the cantilever 20 will be described. In FIG. 6, the polarization directions in the lower piezoelectric layer 61 and the upper piezoelectric layer 62 are connected by arrows. The polarization directions in the detection regions 23A, 23B, 23C, and 23D are from the intermediate electrode 51 toward the upper electrode 31 and the lower electrode 41. The detection region 23A has a lower piezoelectric layer 61A and an upper piezoelectric layer 62B. The detection region 23B has a lower piezoelectric layer 61B and an upper piezoelectric layer 62B. The lower piezoelectric layer 61A is an example of a first lower piezoelectric layer, and the upper piezoelectric layer 62A is an example of a first upper piezoelectric layer. The lower piezoelectric layer 61B is an example of a second lower piezoelectric layer, and the upper piezoelectric layer 62B is an example of a second upper piezoelectric layer.

[0075] [Actions and Effects of the Sound Converter 100C According to the Third Embodiment] The acoustic transducer 100C according to the third embodiment also achieves the same effects as the acoustic transducers 100 and 100B according to the above embodiments. The acoustic transducer 100C according to the third embodiment may be provided with a lower connection electrode 53 and an upper connection electrode 54 branched from the intermediate electrode 51. The intermediate electrodes 51 and the lower electrodes 41 of adjacent detection regions 23A to 23D may be connected via the lower connection electrode 53, and the intermediate electrodes 51 and the upper electrodes 31 of adjacent detection regions 23A to 23C may be connected via the upper connection electrode 54.

[0076] [Sound transducer 100D according to the fourth embodiment] Next, an acoustic transducer 100D according to a fourth embodiment will be described. Fig. 7 is a partial plan view illustrating a portion of the acoustic transducer 100D according to the fourth embodiment. Fig. 8 is a partial enlarged plan view illustrating a portion of the acoustic transducer 100D according to the fourth embodiment. Fig. 9 is a cross-sectional view illustrating a cut surface along line IX-IX in Fig. 7. Fig. 10 is a cross-sectional view illustrating a cut surface along line XX in Fig. 8.

[0077] 7 to 10 differs from the acoustic transducer 100 according to the first embodiment shown in Fig. 3 in that a non-detection area 25D is formed instead of the non-detection area 25, and that a wiring section 90 is provided. In the description of the acoustic transducer 100D according to the fourth embodiment, explanations that are the same as those of the acoustic transducers 100, 100B, and 100C according to the above embodiments may be omitted.

[0078] [Non-detection areas 25A and 25B] 7 and 8, the cantilever 20 of the acoustic transducer 100D includes a plurality of detection regions 23A, 23B, 23C, and 23D. These detection regions 23A, 23B, 23C, and 23D are arranged side by side in the Y-axis direction. A non-detection region 25D is formed between the detection regions 23A to 23D.

[0079] As shown in FIG. 9, in the non-detection area 25D between the detection area 23A and the detection area 23B, a protruding portion 31a of the upper electrode 31, a protruding portion 41a of the lower electrode 41, and a protruding portion 51b of the intermediate electrode 51 are formed.

[0080] The protruding portion 31a protrudes in the Y-axis direction from the upper electrode 31 in the detection region 23A toward the upper electrode 31B in the detection region 23B. The protruding portion 41a protrudes in the Y-axis direction from the lower electrode 41A in the detection region 23A toward the lower electrode 41B in the detection region 23B. The protruding portion 51b protrudes in the Y-axis direction from the intermediate electrode 51B in the detection region 23B toward the intermediate electrode 51A in the detection region 23A.

[0081] [Wiring section 90] The acoustic transducer 100D includes a wiring portion 90 formed in the non-detection region 25D. The wiring portion 90 electrically connects the protruding portion 41a of the lower electrode 41A, the protruding portion 51b of the intermediate electrode 51B, and the protruding portion 31a of the upper electrode 31A in the non-detection region 25D. The wiring portion 90 includes a first joint portion 91, a first rising portion 92, a second joint portion 93, a second rising portion 94, and a third joint portion 95.

[0082] The first bonding portion 91 is formed on the protruding portion 41a of the lower electrode 41A and is bonded to the lower electrode 41A. The first rising portion 92 is connected to the first bonding portion 91 and extends in the thickness direction of the piezoelectric film. The second bonding portion 93 is connected to the first rising portion 92 and is formed on the protruding portion 51b of the intermediate electrode 51B and is bonded to the intermediate electrode 51B. The second rising portion 94 is connected to the second bonding portion 93 and extends in the thickness direction of the piezoelectric film. The third bonding portion 95 is connected to the second rising portion 94 and is formed on the protruding portion 31a of the upper electrode 31A and is bonded to the upper electrode 31A.

[0083] [Actions and Effects of the Sound Converter 100D According to the Fourth Embodiment] The acoustic transducer 100D according to the fourth embodiment also has the same effects as the acoustic transducers 100 and 100B according to the above embodiments. The acoustic transducer 100D according to the fourth embodiment may include a wiring portion 90 that electrically connects the lower electrode 41A, the intermediate electrode 51B, and the upper electrode 31A.

[0084] [Sound transducer 200 according to the fifth embodiment] Next, an acoustic transducer 200 according to a fifth embodiment will be described. FIG. 12 is a plan view illustrating the acoustic transducer 200 according to the fifth embodiment. FIG. 13 is a perspective view illustrating the acoustic transducer 200 according to the fifth embodiment. FIG. 14 is a perspective view illustrating the acoustic transducer 200 according to the fifth embodiment from the bottom side. FIG. 15 is a cross-sectional view illustrating the acoustic transducer 200 according to the fifth embodiment. Note that in each drawing, X-axis, Y-axis, and Z-axis directions, which are orthogonal to each other, may be illustrated. The X-axis, Y-axis, and Z-axis directions do not have to be orthogonal to each other. The X-axis, Y-axis, and Z-axis directions may be arbitrary directions. The X-axis direction is an example of a first direction. The Y-axis direction is an example of a direction intersecting the first direction. In the description of the acoustic transducer 200 according to the fifth embodiment, the same description as for the acoustic transducer 100 according to the above embodiment will be omitted.

[0085] [Support substrate 211] The acoustic transducer 200 includes a support substrate (fixed frame) 211 and a diaphragm (piezoelectric element) 220. The support substrate 211 may be rectangular when viewed in the Z-axis direction. The plate thickness direction of the support substrate 211 is along the Z-axis direction. The support substrate 211 has an upper surface 211a and a lower surface 211b that face each other in the Z-axis direction. An opening 221 is formed in the support substrate 211. The opening 221 is formed so as to penetrate the support substrate 211 in the Z-axis direction. The support substrate 211 is formed from, for example, a silicon wafer. The opening 221 is formed so as to form a circle when viewed in the Z-axis direction.

[0086] [Diaphragm 220] The diaphragm 220 has a piezoelectric film. The diaphragm 220 is formed so as to cover the opening 221. The diaphragm 220 is formed so as to have a circular shape when viewed in the Z-axis direction. An outer periphery 222 of the diaphragm 220 is a fixed end of the diaphragm 220, and is fixed to the upper surface 211a of the support substrate 211. As will be described later, the diaphragm 220 has a first detection area 323, a non-detection area 324, and a second detection area 325. The diaphragm 220 is also called a "diaphragm." Note that the shape of the opening 221 is not limited to a circle, and may be an ellipse or another shape.

[0087] [Piezoelectric film] The piezoelectric film, which is diaphragm 220, deforms in response to sound pressure and generates an electric charge. Fig. 16 is an enlarged cross-sectional view illustrating an example of the piezoelectric film. The piezoelectric film has a lower electrode layer 440, a lower piezoelectric layer (first piezoelectric layer) 460, an intermediate electrode layer 250, an upper piezoelectric layer (second piezoelectric layer) 360, and an upper electrode layer 330. The lower electrode layer 440, the lower piezoelectric layer 460, the intermediate electrode layer 250, the upper piezoelectric layer 360, and the upper electrode layer 330 are laminated in this order.

[0088] [Lower electrode layer 440] Lower electrode layer 440 has lower electrodes 441 to 443 which are thin electrode films. Lower electrode layer 440 is disposed at a position close to opening 221 in the Z-axis direction. Lower electrodes 441 to 443 are disposed apart in the X-axis direction. Lower electrode 441 has a circular shape. Lower electrode 441 is disposed at a position close to center C11 of diaphragm 220 as viewed in the Z-axis direction. Lower electrode 442 has a ring shape as viewed in the Z-axis direction. Lower electrode 442 is disposed outside lower electrode 441 in the radial direction. Lower electrode 443 has a ring shape as viewed in the Z-axis direction. Lower electrode 443 is disposed outside lower electrode 442 in the radial direction.

[0089] [No-electrode formation area 483,484] In the radial direction of diaphragm 220, there is an electrode-free region 483 where no electrode is formed between lower electrode 441 and lower electrode 442. In the radial direction of diaphragm 220, there is an electrode-free region 484 where no electrode is formed between lower electrode 442 and lower electrode 443.

[0090] [Lower piezoelectric layer 460] The lower piezoelectric layer 460 is a piezoelectric thin film, and is formed on the lower electrode layer 440. The lower piezoelectric layer 460 is formed continuously in the radial direction of the vibration plate 220.

[0091] [Intermediate electrode layer 250] The intermediate electrode layer 250 has intermediate electrodes 251 to 253 which are thin electrode films. The intermediate electrode layer 250 is formed on the lower piezoelectric layer 460. The intermediate electrodes 251 to 253 are arranged to be spaced apart in the X-axis direction. The intermediate electrode 251 has a circular shape. The intermediate electrode 251 is arranged at a position close to the center C11 of the vibration plate 220 when viewed in the Z-axis direction. The intermediate electrode 252 has a ring shape when viewed in the Z-axis direction. The intermediate electrode 252 is arranged radially outward of the intermediate electrode 251. The intermediate electrode 253 has a ring shape when viewed in the Z-axis direction. The intermediate electrode 253 is arranged radially outward of the intermediate electrode 252.

[0092] [Electrode non-formation area 281,282] In the radial direction of diaphragm 220, there is an electrode-free region 281 where no electrode is formed between intermediate electrode 251 and intermediate electrode 252. In the radial direction of diaphragm 220, there is an electrode-free region 282 where no electrode is formed between intermediate electrode 252 and intermediate electrode 253.

[0093] [Upper piezoelectric layer 360] The upper piezoelectric layer 360 is a piezoelectric thin film, and is formed on the intermediate electrode layer 250. The upper piezoelectric layer 360 is formed continuously in the radial direction of the vibration plate 220.

[0094] [Top electrode layer 330] The upper electrode layer 330 has upper electrodes 331 to 333 which are thin electrode films. The upper electrode layer 330 is formed on the upper piezoelectric layer 360. The upper electrodes 331 to 333 are arranged to be spaced apart in the X-axis direction. The upper electrode 331 has a circular shape. The upper electrode 331 is arranged at a position close to the center C11 of the diaphragm 220 when viewed in the Z-axis direction. The upper electrode 332 has a ring shape when viewed in the Z-axis direction. The upper electrode 332 is arranged radially outward of the upper electrode 331. The upper electrode 333 has a ring shape when viewed in the Z-axis direction. The upper electrode 333 is arranged radially outward of the upper electrode 332.

[0095] [Material and thickness of piezoelectric thin film] The piezoelectric material used for the lower piezoelectric layer 460 and the upper piezoelectric layer 360 may be, for example, aluminum nitride (AlN) or scandium aluminum nitride (ScAlN (Sc: 1 to 60 at%)), or may be a piezoelectric material having a fluorite structure (hafnium oxide, zirconium oxide, cesium oxide), or a piezoelectric material having a wurtzite structure (zinc oxide, gallium nitride).

[0096] The thickness of the lower piezoelectric layer 460 may be, for example, 100 nm to 1 μm The material of the lower piezoelectric layer 460 may be, for example, ScAlN (Sc: 40 at %), and the thickness of the lower piezoelectric layer 460 may be, for example, 500 nm.

[0097] The thickness of the upper piezoelectric layer 360 may be, for example, 100 nm to 1 μm The material of the upper piezoelectric layer 360 may be, for example, ScAlN (Sc: 40 at %), and the thickness of the upper piezoelectric layer 360 may be, for example, 500 nm.

[0098] [Electrode thin film material and thickness] The thickness of the electrode thin film in the upper electrode layer 330, the intermediate electrode layer 250, and the lower electrode layer 440 may be, for example, 5 nm or more and 100 nm or less. The thickness of the electrode thin film may be, for example, 20 nm. The electrode thin films in the upper electrode layer 330, the intermediate electrode layer 250, and the lower electrode layer 440 may be formed to different thicknesses.

[0099] The material of the electrode thin films in the upper electrode layer 330, the intermediate electrode layer 250, and the lower electrode layer 440 may be formed from, for example, at least one of gold, platinum, tungsten, aluminum, copper, molybdenum, ruthenium, titanium, chromium, and nickel, or an alloy containing one of these. The electrode thin films in the upper electrode layer 330, the intermediate electrode layer 250, and the lower electrode layer 440 may be formed from the same material or different materials.

[0100] [First detection area, non-detection area, and second detection area] As shown in Figures 15 and 16, diaphragm 220 includes first detection areas 323, 423, non-detection areas 324, 424, and second detection areas 325, 425. First detection areas 323, 423 and second detection areas 325, 425 are areas where a physical quantity can be detected. Non-detection areas 324, 424 are areas where a physical quantity is not detected. The physical quantity is, for example, sound pressure.

[0101] The first detection region 323 is a region where the intermediate electrode 251, the upper piezoelectric layer 360, and the upper electrode 331 are arranged to overlap in the Z-axis direction. The first detection region 423 is a region where the lower electrode 441, the lower piezoelectric layer 460, and the intermediate electrode 251 are arranged to overlap in the Z-axis direction. The acoustic transducer 200 can detect the piezoelectric output charge between the lower electrode 441 and the intermediate electrode 251. The acoustic transducer 200 can detect the piezoelectric output charge between the intermediate electrode 251 and the upper electrode 331.

[0102] The non-detection region 324 includes a region where the intermediate electrode 252, the upper piezoelectric layer 360, and the upper electrode 332 are overlapping in the Z-axis direction. The non-detection region 424 includes a region where the lower electrode 442, the lower piezoelectric layer 460, and the intermediate electrode 252 are overlapping in the Z-axis direction. The acoustic transducer 200 cannot detect the piezoelectric output charge between the lower electrode 442 and the intermediate electrode 252. The acoustic transducer 200 cannot detect the piezoelectric output charge between the intermediate electrode 252 and the upper electrode 332.

[0103] The second detection region 325 is a region where the intermediate electrode 253, the upper piezoelectric layer 360, and the upper electrode 333 are arranged to overlap in the Z-axis direction. The second detection region 425 is a region where the lower electrode 443, the lower piezoelectric layer 460, and the intermediate electrode 253 are arranged to overlap in the Z-axis direction. The acoustic transducer 200 can detect the piezoelectric output charge between the lower electrode 443 and the intermediate electrode 253. The acoustic transducer 200 can detect the piezoelectric output charge between the intermediate electrode 253 and the upper electrode 333.

[0104] The first detection regions 323, 423 are formed at positions close to the center of the diaphragm 220. The non-detection regions 324, 424 are formed further outward than the first detection regions 323, 423 in the radial direction of the diaphragm 220. The second detection regions 325, 425 are formed further outward than the non-detection regions 324, 424 in the radial direction of the diaphragm 220.

[0105] [Outer diameters of first detection area 323, non-detection area 324, and second detection area 325] 12, the outer diameter Φ323 of the first detection region 323 is, for example, 0.59 mm, the outer diameter Φ324 of the non-detection region 324 is, for example, 0.81 mm, and the outer diameter Φ325 of the second detection region 325 is 1 mm.

[0106] [Split position] 16, the lower electrode layer 440 has no-electrode regions 483 and 484. The intermediate electrode layer 250 has no-electrode regions 281 and 282. The upper electrode layer 330 has no-electrode regions 381 and 382.

[0107] The electrode-free regions 281, 282, 381, 382, ​​483, and 484 may be referred to as “division positions.” These electrode-free regions 281, 282, 381, 382, ​​483, and 484 are arranged at different positions in the radial direction of the diaphragm 220.

[0108] The electrode-free region 381 is disposed more inward than the electrode-free region 281 in the radial direction of the diaphragm 220. The electrode-free region 281 is disposed more inward than the electrode-free region 483 in the radial direction of the diaphragm 220.

[0109] The electrode-free region 382 is disposed further outward than the electrode-free region 282 in the radial direction of the diaphragm 220. The electrode-free region 282 is disposed further outward than the electrode-free region 484 in the radial direction of the diaphragm 220.

[0110] In diaphragm 220, multiple electrode-free regions 281, 282, 381, 382, ​​483, and 484 are formed in positions that do not overlap one another when viewed in the Z-axis direction, thereby preventing a decrease in strength of diaphragm 220. Note that piezoelectric thin films are formed in electrode-free regions 281, 282, 483, and 484.

[0111] The crystallinity of the piezoelectric thin film above the boundary between the end of the lower electrode 441 and the electrode-free region 483 is lower than the crystallinity of the piezoelectric thin film above the lower electrode 441. Similarly, the crystallinity of the piezoelectric thin film above the boundary between the electrode and the electrode-free region is lower than the crystallinity of the piezoelectric thin film above the electrode.

[0112] The division position of electrode-free region 483 is located outside first detection region 423 in the radial direction of diaphragm 220. The division position of electrode-free region 484 is located inside second detection region 425 in the radial direction of diaphragm 220. This does not hinder the crystal growth of the piezoelectric thin film that generates electric charge. In acoustic transducer 200, the crystallinity of the piezoelectric thin film is high in first detection region 423 and second detection region 425 that generate electric charge.

[0113] The division position of electrode-free region 281 is located outside first detection region 323 in the radial direction of diaphragm 220. The division position of electrode-free region 282 is located inside second detection region 325 in the radial direction of diaphragm 220. This does not hinder crystal growth of the piezoelectric thin film that generates electric charge. In acoustic transducer 200, the crystallinity of the piezoelectric thin film is high in first detection region 323 and second detection region 325 that generate electric charge.

[0114] [Piezoelectric film connection] In vibration plate 220, which is a piezoelectric film (piezoelectric element), the electrodes of first detection regions 323, 423 are electrically connected in parallel. The electrodes of first detection region 323 include upper electrode 331 and intermediate electrode 251. The electrodes of first detection region 423 include lower electrode 441 and intermediate electrode 251. The electrodes of second detection regions 325, 425 are electrically connected in parallel. The electrodes of second detection region 325 include upper electrode 333 and intermediate electrode 253. The electrodes of second detection region 425 include lower electrode 443 and intermediate electrode 253.

[0115] The electrodes in the first and second detection regions are electrically connected in series: specifically, upper electrode 331 and upper electrode 333 are connected in series, and lower electrode 441 and lower electrode 443 are connected in series, or intermediate electrode 251 and intermediate electrode 253 are connected in series.

[0116] [Operation and effect of the acoustic transducer 200 according to the fifth embodiment] Acoustic transducer 200 according to the fifth embodiment includes support substrate (fixed frame) 211 and diaphragm 220, which is a piezoelectric element fixed to support substrate 211. Diaphragm 220 has first detection regions 323, 423 and second detection regions 325, 425, which are multiple detection regions capable of detecting physical quantities, and non-detection regions 324, 424, which do not detect physical quantities. Electrodes in the multiple detection regions are electrically connected in series.

[0117] In the acoustic transducer 200 of this embodiment, the physical quantity can be detected by detecting the deformation of the diaphragm 220 due to deformation of the diaphragm 220. In the acoustic transducer 200, first detection areas 323, 423 and second detection areas 325, 425 are formed, and the electrodes of these multiple detection areas are electrically connected in series, thereby improving the sensitivity of the diaphragm 220.

[0118] In the acoustic transducer 200, the piezoelectric element is a vibration plate (diaphragm) 220, and an outer periphery 222 of the vibration plate 220 (outer periphery of the diaphragm) is a fixed end fixed to a support substrate 211.

[0119] In the acoustic transducer 200, the multiple detection regions include first detection regions 323 and 423 which are inner detection regions arranged at positions close to the center C11 of the diaphragm 220 in the radial direction of the diaphragm 220, and second detection regions 325 and 425 which are outer detection regions arranged at positions far from the center C11 of the diaphragm 220 in the radial direction of the diaphragm 220. Non-detection regions 324 and 424 are formed between the inner detection regions and the outer detection regions in the circumferential direction of the diaphragm 220.

[0120] In the acoustic transducer 200 of this embodiment, as the diaphragm 220 deforms, charges are generated in response to the diaphragm 220, and the charges generated are detected in the first detection areas 323, 423 and the second detection areas 325, 425. In the acoustic transducer 200, the electrodes are divided in the radial direction of the diaphragm 220, thereby forming the first detection areas 323, 423, the non-detection areas 324, 424, and the second detection areas 325, 425. In such an acoustic transducer 200, the sensitivity for detecting charges in response to sound pressure can be improved.

[0121] 17 is a side view illustrating the distribution of electric charges generated on diaphragm 220 as it deforms under sound pressure. Diaphragm 220 has outer periphery 222 fixed to support substrate 211 in the radial direction. As shown in FIG. 17, the area near inflection point P12 is less likely to deform, and the amount of electric charge generated is small. Inflection point P12 and the area nearby, where the amount of electric charge generated is small, are included in non-detection areas 324, 424.

[0122] In contrast, the area close to the center C11 of the diaphragm 220 and near the outer periphery 222 of the diaphragm 220 are largely deformed and generate a large amount of electric charge. The center C11 of the diaphragm 220 and the area around it are included in the first detection areas 323, 423. The area near the outer periphery 222 of the diaphragm 220 is included in the second detection areas 325, 425. In the acoustic transducer 200, the area including the inflection point P12, where little electric charge is generated, is not included in the first detection areas 323, 423 and the second detection areas 325, 425. This makes it possible to improve the signal-to-noise ratio in the acoustic transducer 200 and to detect electric charge with high sensitivity.

[0123] [Electrode end shape] Next, the shape of the electrode end portions will be described. As shown in Fig. 16, the end portions of the upper electrodes 331-333, the lower electrodes 441-443, and the intermediate electrodes 251-253 may be tapered. The electrode end portions are end portions that face each other in the radial direction of the diaphragm 220. The tapered shape of the electrode end portions is formed so that the lower side protrudes more than the upper side.

[0124] In this way, by tapering the ends of the lower electrodes 441 to 443, it is possible to make the steps gentler at the boundaries between the lower electrodes 441 to 443 and the electrode-free regions 483, 484. This makes it possible to suppress deterioration in the crystallinity of the piezoelectric layer 460. The same applies to the boundaries between the other electrodes and the electrode-free regions.

[0125] [Sound transducer 200B according to the sixth embodiment] Next, an acoustic transducer 200B according to a sixth embodiment will be described. FIG. 18 is a plan view illustrating the acoustic transducer 200B according to the sixth embodiment. FIG. 19 is a cross-sectional view illustrating the acoustic transducer according to the sixth embodiment, taken along line IX-IX in FIG. 18. The acoustic transducer 200B according to the sixth embodiment shown in FIGS. 18 and 19 differs from the acoustic transducer 200 according to the fifth embodiment shown in FIG. 12 in that the acoustic transducer 200B according to the sixth embodiment includes a plurality of upper electrodes 331B, 333B divided in the circumferential direction, a plurality of lower electrodes 441B, 443B divided in the circumferential direction, a plurality of intermediate electrodes 251B, 253B divided in the circumferential direction, and electrode-free regions 385, 386 extending in the radial direction. Note that, in the description of the acoustic transducer 200B according to the sixth embodiment, descriptions similar to those of the acoustic transducer 200 according to the fifth embodiment may be omitted.

[0126] [Laminate 300B] 19, the acoustic transducer 200B includes laminates 300B and 400B. The laminate 300B includes an upper electrode layer 330B, a piezoelectric layer 360, and an intermediate electrode layer 250B. The upper electrode layer 330B includes a plurality of upper electrodes 331B divided in the circumferential direction, a circumferentially continuous upper electrode 332, and a plurality of upper electrodes 333B divided in the circumferential direction. The intermediate electrode layer 250B includes a plurality of intermediate electrodes 251B divided in the circumferential direction, a circumferentially continuous intermediate electrode 252, and a plurality of intermediate electrodes 253B divided in the circumferential direction.

[0127] [First detection area 323B] The laminate 300B has a first detection region 323B, a non-detection region 324B, and a second detection region 325B. The first detection region 323B has a plurality of upper electrodes 331B, a piezoelectric layer 360, and a plurality of intermediate electrodes 251B. The first detection region 323B includes a plurality of piezoelectric elements. In the first detection region 323B, the piezoelectric elements have an upper electrode 331B, a piezoelectric layer 360, and an intermediate electrode 251B.

[0128] [Second detection area 325B] The second detection region 325B includes a plurality of upper electrodes 333B, a piezoelectric layer 360, and a plurality of intermediate electrodes 253B. The second detection region 325B includes a plurality of piezoelectric elements. In the second detection region 325B, the piezoelectric elements include the upper electrodes 333B, the piezoelectric layer 360, and the intermediate electrodes 253B.

[0129] As shown in FIG. 18, the upper electrode layer 330B has electrode-free regions 381 and 382 and electrode-free regions 385 and 386 formed therein.

[0130] [Electrode non-formation area 385] The electrode-free regions 385 divide the upper electrode into multiple regions in the first detection region 323B. The electrode-free regions 385 extend radially from the center of the diaphragm 220B. The multiple electrode-free regions 385 are arranged at equal intervals in the circumferential direction. The multiple upper electrodes 331B have approximately the same area. The acoustic transducer 200B has, for example, ten upper electrodes 331B.

[0131] [Electrode non-formation area 386] The electrode-free regions 386 divide the upper electrode into multiple sections in the second detection region 325B. The electrode-free regions 386 extend radially from the electrode-free regions 382 toward the outer periphery 222 of the diaphragm 220. The multiple electrode-free regions 386 are arranged at equal intervals in the circumferential direction.

[0132] [Laminate 400B] 19, the laminate 400B has an intermediate electrode layer 250B, a piezoelectric layer 460, and a lower electrode layer 440B. The intermediate electrode layer 250B serves as both the laminate 300B and the laminate 400B. The lower electrode layer 440B has a plurality of lower electrodes 441B divided in the circumferential direction, a lower electrode 442 that is continuous in the circumferential direction, and a plurality of lower electrodes 443B divided in the circumferential direction.

[0133] [First detection area 423B] The laminate 400B has a first detection region 423B, a non-detection region 424B, and a second detection region 425B. The first detection region 423B has a plurality of intermediate electrodes 251B, a piezoelectric layer 460, and a plurality of lower electrodes 441B. The first detection region 423B includes a plurality of piezoelectric elements. In the first detection region 423B, the piezoelectric elements have an intermediate electrode 251B, a piezoelectric layer 460, and a lower electrode 441B. In the first detection region 423B, the areas of the plurality of lower electrodes 441B are approximately equal to each other.

[0134] [Second detection area 425B] The second detection region 425B has a plurality of intermediate electrodes 253B, a piezoelectric layer 460, and a plurality of lower electrodes 443B. The second detection region 425B includes a plurality of piezoelectric elements. In the second detection region 425B, the piezoelectric elements have the intermediate electrode 253B, the piezoelectric layer 460, and a lower electrode 443B. In the second detection region 425B, the areas of the plurality of lower electrodes 443B are approximately equal to each other.

[0135] The lower electrode layer 440B and the intermediate electrode layer 250B of the stack 400B include a radially extending electrode-free region, similar to the upper electrode layer 330B of the stack 300B.

[0136] [Capacitance of piezoelectric element] In the laminate 300B, the capacitances of the plurality of piezoelectric elements aligned in the circumferential direction of the diaphragm 220B are equal to each other. In the laminate 400B, the capacitances of the plurality of piezoelectric elements aligned in the circumferential direction of the diaphragm 220B are approximately equal to each other.

[0137] [Series connection of multiple piezoelectric elements] In the vibration plate 220B, the plurality of piezoelectric elements arranged in the circumferential and radial directions are electrically connected in series.

[0138] [Actions and Effects of the Sound Converter 200B According to the Sixth Embodiment] The sound transducer 200B according to the sixth embodiment also provides the same effects as the sound transducer 200 according to the fifth embodiment.

[0139] In acoustic transducer 200B, the multiple detection regions include first detection regions 323B and 423B, which are inner detection regions located near center C11 of diaphragm 220B in the radial direction of diaphragm 220B, and second detection regions 325B and 425B, which are outer detection regions located far from center C11 of diaphragm 220B in the radial direction of diaphragm 220B. Non-detection regions 324, 424 include electrode-free regions 381, 382 formed between the inner and outer detection regions in the circumferential direction of diaphragm 220B, and multiple electrode-free regions 385, 386 extending in the radial direction of the diaphragm and formed at intervals in the circumferential direction of the diaphragm.

[0140] According to such an acoustic transducer 200B, by having the electrode-free areas 385 and 386 extending in the radial direction, the electrodes in the detection area can be divided into a plurality of areas.

[0141] [Modification of the acoustic transducer 200B according to the sixth embodiment] In acoustic transducer 200B, diaphragm (piezoelectric element) 220B has a piezoelectric film, and the piezoelectric film includes a lower electrode layer 440B, a lower piezoelectric layer 460 formed on lower electrode layer 440B, an intermediate electrode layer 250B formed on lower piezoelectric layer 460, an upper piezoelectric layer 360 formed on intermediate electrode layer 250B, and an upper electrode layer 330B formed on upper piezoelectric layer 360. Between a plurality of detection regions (first detection regions 323B, 423B and second detection regions 325B, 425B), there are provided electrode-free regions (first electrode-free regions) where the upper electrode and lower electrode are not formed, or electrode-free regions (second electrode-free regions) where the intermediate electrode is not formed.

[0142] In acoustic transducer 200B, when an electrode no-formation region (first electrode no-formation region) is formed in the upper electrode and the lower electrode, an electrode no-formation region (second electrode no-formation region) may not be formed in the intermediate electrode. In acoustic transducer 200B, when an electrode no-formation region (second electrode no-formation region) is formed in the intermediate electrode, an electrode no-formation region (first electrode no-formation region) 381, 382, ​​483, 484 may not be formed in the upper electrode and the lower electrode.

[0143] Furthermore, in the detection region, the upper electrode, intermediate electrode, and lower electrode may be divided in the circumferential direction. In the circumferential direction, the division position (electrode-free region) of the upper electrode and the division position of the intermediate electrode may be different. Similarly, in the circumferential direction, the division position of the lower electrode and the division position of the intermediate electrode may be different.

[0144] [Circuit diagram of the acoustic transducer 200B according to the sixth embodiment] Next, a circuit diagram of the sound transducer 200B according to the sixth embodiment will be described below. Fig. 20 is a circuit diagram of the sound transducer 200B according to the sixth embodiment.

[0145] 20, the acoustic transducer 200B has a MEMS microphone chip 201. A diaphragm 220B is mounted on the MEMS microphone chip 201. The diaphragm 220B has a plurality of first detection areas 323B, 423B and second detection areas 325B, 425B.

[0146] The multiple first detection regions 323B, 423B include an upper electrode 331B, an intermediate electrode 251B, and a lower electrode 441B. The multiple second detection regions 325B, 425B include an upper electrode 333B, an intermediate electrode 253B, and a lower electrode 443B. The upper electrode 331B includes upper electrodes 331B-1, 331B-2, ..., 331B-n that are divided into n pieces in the circumferential direction, where n is a natural number. The same applies to the other upper electrodes, intermediate electrodes, and lower electrodes.

[0147] In the first detection areas 323B and 423B of the acoustic transducer 200B, the piezoelectric output charge between the upper electrode 331B and the intermediate electrode 251B, and the piezoelectric output charge between the intermediate electrode 251B and the lower electrode 441B can be detected. The multiple piezoelectric elements arranged in the circumferential direction are connected in series.

[0148] In the second detection areas 325B and 425B of the acoustic transducer 200B, the piezoelectric output charge between the upper electrode 333B and the intermediate electrode 253B, and the piezoelectric output charge between the intermediate electrode 253B and the lower electrode 443B can be detected. The multiple piezoelectric elements arranged in the circumferential direction are connected in series.

[0149] Furthermore, MEMS microphone chip 201 has pads 213 and 214. Electrodes of a plurality of piezoelectric elements are connected to pads 213 and 214. Acoustic transducer 200B includes IC 202 connected to pad 213. IC 202 is an amplifier that amplifies the output signal of the piezoelectric element of diaphragm 220B. Note that IC 202 may be provided with a function of amplifying the output signal of the piezoelectric element of diaphragm 220B and then performing AD (analog-to-digital) conversion.

[0150] The polarity of the charge generated in the second detection regions 325B, 425B is opposite to the polarity of the charge generated in the first detection regions 323B, 423B. Therefore, the second detection regions 325B, 425B and the first detection regions 323B, 423B are connected in series with the wiring reversed.

[0151] [Electrode connection] In the acoustic transducer 200B, the upper electrodes 331B and the intermediate electrodes 251B of the first detection areas 323B may be electrically connected in series. Similarly, the upper electrodes 333B and the intermediate electrodes 253B of the second detection areas 325B may be electrically connected in series.

[0152] In acoustic transducer 200B, lower electrodes 441B and intermediate electrodes 251B of multiple first detection areas 423B may be electrically connected in series. Similarly, lower electrodes 433B and intermediate electrodes 253B of multiple second detection areas 425B may be electrically connected in series.

[0153] In the sound transducer 200B, the upper electrodes and lower electrodes of each of the plurality of detection regions may be electrically connected in parallel.

[0154] [Relationship between sensing area diameter ratio and normalized SNR] Next, the relationship between the sensing area diameter ratio and the normalized SNR will be described. Fig. 21 is a graph showing the relationship between the sensing area diameter ratio and the normalized SNR. In Fig. 21, the horizontal axis represents the sensing area diameter ratio [%], and the vertical axis represents the normalized SNR [%]. The graph shown in Fig. 21 is a graph showing the relationship between the sensing area diameter ratio and the normalized SNR in the sound transducer 200 according to the fifth embodiment shown in Fig. 12.

[0155] The "sensing area ratio" can be expressed by the following formula (1). Sensing area ratio = (electrode separation radius / diaphragm radius) × 100 (1) The "electrode section separation section radius" may be the radius of inner detection area 323. The "diaphragm radius" may be the radius of diaphragm 220. In Figure 12, the diameter φ323 of inner detection area 323 and the diameter φ325 of diaphragm 220 are shown.

[0156] The inner diameter of opening 221 covered by diaphragm 220 was set as 100% of the sensing area diameter ratio. When 71% of the area is covered by an electrode-free area, the normalized SNR is set to 100%. In FIG. 12, "◯" indicates the position of the boundary between inner detection area 323 and non-detection area 324. In FIG. 12, "X" indicates the position of the boundary between outer detection area 325 and non-detection area 324.

[0157] The SNR normalized value of inner detection region 323 is a value obtained when the boundary between outer detection region 325 and non-detection region 324 is set to 71% and the outer diameter Φ323 of inner detection region 323 is changed.

[0158] The SNR normalized value of outer detection region 325 is a value obtained when the boundary between inner detection region 323 and non-detection region 324 is set to 71% and the inner diameter Φ324 of outer detection region 325 is changed.

[0159] 21, the SNR normalized value of the inner detection area 323 was maximum at point P21. The sensing area diameter ratio at point P21 was 59%.

[0160] 21, the SNR normalized value of the outer detection area 325 was maximum at point P22. The sensing area diameter ratio at point P22 was 81%.

[0161] When the sensing area diameter ratio of the inner detection area 323 was 44% or more and 71% or less, the normalized SNR value was 100% or more. When the sensing area diameter ratio of the inner detection area 323 was 49% or more and 67% or less, the normalized SNR value was 104% or more. When the sensing area diameter ratio of the inner detection area 323 was 51% or more and 65% or less, the normalized SNR value was 106% or more.

[0162] The sensing area diameter ratio of the inner detection area 323 is preferably 44% or more and 71% or less, more preferably 49% or more and 67% or less, and even more preferably 51% or more and 65% or less.

[0163] When the sensing area diameter ratio of the outer detection area 325 was 71% or more and 89% or less, the normalized SNR value was 100% or more. When the sensing area diameter ratio of the outer detection area 325 was 75% or more and 87% or less, the normalized SNR value was 104% or more. When the sensing area diameter ratio of the outer detection area 325 was 78% or more and 84% or less, the normalized SNR value was 106% or more.

[0164] The sensing area diameter ratio of outer detection area 325 is preferably 71% or more and 89% or less, more preferably 75% or more and 87% or less, and even more preferably 78% or more and 84% or less.

[0165] When the sensing area diameter ratio of inner detection area 323 is 71% and the sensing area diameter ratio of outer detection area 325 is 71%, the electrode division position may be at the 71% position.

[0166] In the acoustic transducer 200, when the sensing area diameter ratio of the outer detection area 325 is 71% or more and 89% or less, the sensing area diameter ratio of the inner detection area 323 may be an outer value of the range of 44% or more and 71% or less. In such a case, the SNR normalized value may become high.

[0167] In the acoustic transducer 200, when the sensing area diameter ratio of the inner detection area 323 is 44% or more and 71% or less, the sensing area diameter ratio of the outer detection area 325 may be a value outside the range of 71% or more and 89% or less. In such a case, the SNR normalized value may become high.

[0168] It should be noted that the present invention is not limited to the configurations shown here, and other embodiments may be possible in which other components are combined with the configurations described in the above embodiments. In this regard, the present invention can be modified within the scope of the present invention, and can be appropriately determined depending on the application form.

[0169] In the above embodiment, the acoustic transducer 100 is illustrated as including a cantilever 20 with a cantilever structure having a free end 21 and a fixed end 22, but the acoustic transducer 100 is not limited to this. The acoustic transducer 100 may also be provided with a doubly supported beam structure in which both ends of the beam structure are connected to opposing portions of the fixed frame 10 as fixed ends 22. In an acoustic transducer 100 with this structure, when sound pressure is applied, the central portion of the doubly supported beam bends in the thickness direction. The acoustic transducer 100 may also be provided with a doubly supported beam instead of the cantilever 20.

[0170] In the above embodiments, acoustic transducers 100, 100B, 100C, and 100D are described as having a pair of cantilevers 20A and 20B, but acoustic transducers 100, 100B, 100C, and 100D may also have one cantilever 20 or three or more cantilevers 20. [Explanation of symbols]

[0171] 100, 100B, 100C, 100D, 200, 200B: acoustic transducer, 10: fixed frame, 20: cantilever, 20A: cantilever (first cantilever), 20B: cantilever (second cantilever), 21: free end, 22: fixed end, 23, 23A, 23B, 23C, 23D: multiple detection areas, 24: non-detection area, 25: non-detection area, 25A: non-detection area (first electrode non-forming area), 25B: non-detection area (second electrode non-forming area) forming area), 25C, 25D: non-detection area, 30: upper electrode, 31: upper electrode, 40: lower electrode, 41: lower electrode, 50: intermediate electrode, 51: intermediate electrode, 53: lower connecting electrode, 54: upper connecting electrode, 61: lower piezoelectric layer, 61A: lower piezoelectric layer (first lower piezoelectric layer), 61B: lower piezoelectric layer (second lower piezoelectric layer), 62: upper piezoelectric layer, 62A: upper piezoelectric layer (first upper piezoelectric layer), 62B: upper piezoelectric layer (second upper piezoelectric layer), 220, 220B : Vibration plate (piezoelectric element, diaphragm), 222: Outer periphery (fixed end), 323, 323B: First detection area (inner detection area), 324: Non-detection area (first non-detection area), 325, 325B: Second detection area (outer detection area), 331, 331B: Upper electrode of detection area, 332: Upper electrode of non-detection area, 333, 333B: Upper electrode of detection area, 381, 382: Non-electrode area, 385, 386: Non-electrode area (second non-detection area) , 423, 423B: first detection area (inner detection area), 424: non-detection area (first non-detection area), 425, 425B: second detection area (outer detection area), 431, 431B: upper electrode of detection area, 432: upper electrode of non-detection area, 433, 433B: upper electrode of detection area, 481, 482: electrode-free area, C11: center of diaphragm, X: X-axis direction (first direction), Y: Y-axis direction (second direction), Z: Z-axis direction (thickness direction).

Claims

1. A fixed frame and a piezoelectric element fixed to the fixed frame, The piezoelectric element is a plurality of detection areas capable of detecting physical quantities; a non-detection region in which a physical quantity is not detected, An acoustic transducer in which the electrodes of the plurality of detection regions are electrically connected in series.

2. the piezoelectric element is a cantilever having one end fixed to the fixed frame and the other end free, the cantilever extending from the fixed frame to the inside of the fixed frame; The cantilever is 2. The acoustic transducer according to claim 1, further comprising a first cantilever and a second cantilever that face each other in a first direction in which the cantilevers extend.

3. 3. The acoustic transducer according to claim 2, wherein the electrodes in the plurality of detection regions of the first cantilever and the electrodes in the plurality of detection regions of the second cantilever are electrically connected in series.

4. the plurality of detection areas are arranged closer to the fixed end, The acoustic transducer according to claim 2 , wherein the non-detection region is disposed closer to the free end.

5. the piezoelectric element is a diaphragm, 2. The acoustic transducer according to claim 1, wherein the outer periphery of the diaphragm is a fixed end fixed to the fixed frame.

6. The plurality of detection regions include: an inner detection area disposed at a position close to the center of the diaphragm in the radial direction of the diaphragm; an outer detection region disposed at a position far from the center of the diaphragm in the radial direction of the diaphragm, The non-detection region is a ring-shaped, continuous, circumferentially non-electrode-formed region of the diaphragm, the non-electrode-formed region being formed between the inner detection region and the outer detection region; 6. The acoustic transducer according to claim 5, further comprising: a plurality of radially extending electrode-free regions of the diaphragm, the electrode-free regions being spaced apart from one another in the circumferential direction of the diaphragm.

7. the piezoelectric element has a piezoelectric film, The piezoelectric film is A lower electrode; a lower piezoelectric layer formed on the lower electrode; an intermediate electrode formed on the lower piezoelectric layer; an upper piezoelectric layer formed on the intermediate electrode; an upper electrode formed on the upper piezoelectric layer; The acoustic transducer according to claim 1, further comprising a first electrode-free region in which the upper electrode and the lower electrode are not formed, or a second electrode-free region in which the intermediate electrode is not formed, between the plurality of detection regions.

8. the piezoelectric element is a diaphragm, the outer periphery of the diaphragm is a fixed end fixed to the fixed frame, the lower electrodes and the upper electrodes of the plurality of detection regions, or the intermediate electrodes of the plurality of detection regions, are electrically connected in series; The acoustic transducer according to claim 7 , wherein the upper electrode and the lower electrode in each of the plurality of detection regions are electrically connected in parallel.

9. The acoustic transducer according to claim 7 , wherein the first electrode-free regions and the second electrode-free regions are alternately arranged in a direction in which the plurality of detection regions are arranged.

10. the plurality of detection regions include a first detection region and a second detection region; The first detection area is a first lower electrode; a first lower piezoelectric layer formed on the first lower electrode; a first intermediate electrode formed on the first lower piezoelectric layer; a first upper piezoelectric layer formed on the first intermediate electrode; a first upper electrode formed on the first upper piezoelectric layer; The second detection area is A second lower electrode; a second lower piezoelectric layer formed on the second lower electrode; a second intermediate electrode formed on the second lower piezoelectric layer; a second upper piezoelectric layer formed on the second intermediate electrode; a second upper electrode formed on the second upper piezoelectric layer, Between the first detection area and the second detection area, a lower connection electrode that connects the first lower electrode and the second intermediate electrode; The acoustic transducer according to claim 1 , further comprising an upper connection electrode that connects the first upper electrode and the second intermediate electrode.

11. the plurality of detection regions include a first detection region and a second detection region; The first detection area is a first lower electrode; a first lower piezoelectric layer formed on the first lower electrode; a first intermediate electrode formed on the first lower piezoelectric layer; a first upper piezoelectric layer formed on the first intermediate electrode; a first upper electrode formed on the first upper piezoelectric layer; The second detection area is A second lower electrode; a second lower piezoelectric layer formed on the second lower electrode; a second intermediate electrode formed on the second lower piezoelectric layer; a second upper piezoelectric layer formed on the second intermediate electrode; a second upper electrode formed on the second upper piezoelectric layer, Between the first detection area and the second detection area, the first lower electrode extends toward the second lower electrode in a second direction intersecting a first direction in which the cantilever extends, the second intermediate electrode extends in the second direction toward the first intermediate electrode; the first upper electrode extends in the second direction toward the second upper electrode; The acoustic transducer according to claim 2 , further comprising a wiring portion connecting the protruding portion of the first lower electrode, the protruding portion of the second intermediate electrode, and the protruding portion of the first upper electrode.

12. The wiring portion is a first bonding portion formed on the first lower electrode and bonded to the first lower electrode; a first rising portion connected to the first joint portion and extending in a thickness direction of the piezoelectric film; a second bonding portion connected to the first rising portion and formed on the second intermediate electrode and bonded to the second intermediate electrode; a second rising portion connected to the second joint portion and extending in a thickness direction of the piezoelectric film; The acoustic transducer according to claim 11 , further comprising: a third joint portion connected to the second rising portion, formed on the first upper electrode, and connected to the first upper electrode.

13. A fixed frame and a doubly supported beam, both ends of which are fixed to opposing portions of the fixed frame; The doubly supported beam is a plurality of detection areas capable of detecting physical quantities; a non-detection region in which a physical quantity is not detected, An acoustic transducer in which the electrodes of the plurality of detection regions are electrically connected in series.

Images