Acoustic piezoelectric structure and performance optimization method thereof, piezoelectric microphone and electronic equipment

Abstract

The invention provides an acoustic piezoelectric structure and a performance optimization method thereof, a piezoelectric microphone and electronic equipment, and relates to the technical field of acoustic sensors, a piezoelectric film layer comprises a plurality of cantilever beam vibrating diaphragms distributed on the same layer, the plurality of cantilever beam vibrating diaphragms are connected to a support body, and a gap is formed between the free ends of at least two cantilever beam vibrating diaphragms. The flexible connecting part is located at the gap and is connected with the free ends of the at least two cantilever beam vibrating diaphragms forming the gap, and the flexible connecting part meets the formula that d is in direct proportion to A3 / E, d is the deformation quantity of the center of the flexible connecting part, A is the ratio of the width of the flexible connecting part at the gap to the thickness of the flexible connecting part, and E is the Young modulus of the flexible connecting part. Therefore, by defining a plurality of parameters influencing the resonant frequency and the low-frequency response capability of the acoustic piezoelectric structure and the regulation and control relationship of the plurality of parameters, the acoustic piezoelectric structure is enabled to have relatively appropriate low-frequency response capability and resonant frequency when being applied to the piezoelectric microphone.

Description

Technical Field

[0001] The present application relates to the technical field of acoustic sensors, and in particular to an acoustic piezoelectric structure and a performance optimization method thereof, a piezoelectric microphone, and an electronic device. Background Art

[0002] In recent years, MEMS piezoelectric microphones manufactured using MEMS (micro-electromechanical systems) technology have been increasingly used in smart devices, and electronic devices such as smartphones, wearable products, sports cameras or digital cameras all have the function of recognizing surrounding conditions through sound. Therefore, higher requirements are placed on the audio characteristics of MEMS acoustic microphones.

[0003] Existing piezoelectric microphones mainly achieve acoustic-electric conversion through the piezoelectric part they contain. As for the piezoelectric part, it usually has a diaphragm with a slit, but the presence of the slit will reduce the response ability of the piezoelectric microphone to low frequencies. Summary of the invention

[0004] The purpose of the present application is to provide an acoustic piezoelectric structure and a performance optimization method thereof, a piezoelectric microphone and an electronic device to address the deficiencies in the above-mentioned prior art.

[0005] To achieve the above purpose, the technical solution adopted in the embodiment of the present application is as follows:

[0006] According to one aspect of an embodiment of the present application, an acoustic piezoelectric structure is provided, which is applied to a piezoelectric microphone, including:

[0007] Support body;

[0008] A piezoelectric film layer, the piezoelectric film layer includes a plurality of cantilever beam diaphragms distributed in the same layer, the plurality of cantilever beam diaphragms are all connected to a support body, and a gap is formed between free ends of at least two cantilever beam diaphragms;

[0009] A flexible connection part, the flexible connection part is located at the gap and is respectively connected to the free ends of at least two cantilever beam diaphragms forming the gap, and the flexible connection part satisfies: d∝A 3 / E, wherein d is the deformation at the center of the flexible connection, A is the ratio of the width of the flexible connection at the gap to the thickness of the flexible connection, and E is the Young's modulus of the flexible connection.

[0010] Optionally, the flexible connection portion satisfies: A 3 / E>0.001MPa -1 .

[0011] Optionally, the flexible connection portion satisfies: A 3 / E≥27MPa -1 .

[0012] Optionally, when the acoustic wave acts on the piezoelectric film layer:

[0013] The stress and amplitude of the flexible connection in the thickness direction are linearly related;

[0014] The stress of the flexible connection portion in the direction perpendicular to the thickness is linearly related to the amplitude.

[0015] Optionally, the flexible connection portion blocks part or all of the gap.

[0016] Optionally, the flexible connection portion is located in the gap, and a thickness of the flexible connection portion is less than or equal to a thickness of the cantilever beam diaphragm.

[0017] Optionally, the flexible connection portion is located outside the gap, and the flexible connection portion is located on the top surface or the bottom surface of the piezoelectric film layer.

[0018] According to another aspect of an embodiment of the present application, a piezoelectric microphone is provided, comprising an ASIC circuit and any one of the above-mentioned acoustic piezoelectric structures, wherein the acoustic piezoelectric structure and the ASIC circuit are connected.

[0019] Optionally, the piezoelectric microphone further comprises:

[0020] The substrate, the acoustic piezoelectric structure and the ASIC circuit are all arranged on the substrate, and the substrate is provided with an acoustic hole, and the acoustic hole corresponds to the piezoelectric film layer of the acoustic piezoelectric structure;

[0021] The cover shell is buckled on the substrate and covers the acoustic piezoelectric structure and the ASIC circuit.

[0022] According to another aspect of the embodiments of the present application, an electronic device is provided, including a device body and any one of the above-mentioned piezoelectric microphones, wherein the piezoelectric microphone is disposed in the device body.

[0023] In another aspect of the embodiments of the present application, a method for optimizing the performance of an acoustic piezoelectric structure is provided, wherein the acoustic piezoelectric structure includes a plurality of cantilever beam diaphragms distributed in the same layer, a gap is formed between the free ends of at least two cantilever beam diaphragms, and a flexible connection portion is provided at the gap;

[0024] Methods include:

[0025] Obtaining performance expectations for acoustic piezoelectric structures;

[0026] The optimization parameters of the flexible connection are obtained according to the expected performance value and the optimization model of the flexible connection, where the optimization parameters are A 3 / E, A is the ratio of the width of the flexible connection at the gap to the thickness of the flexible connection, E is the Young's modulus of the flexible connection, and the optimization model of the flexible connection is: d∝A 3 / E, where d is the deformation at the center of the flexible connection.

[0027] The beneficial effects of this application include:

[0028] The present application provides an acoustic piezoelectric structure and a performance optimization method thereof, a piezoelectric microphone and an electronic device. The acoustic piezoelectric structure is applied to a piezoelectric microphone, comprising: a support body, a piezoelectric film layer and a flexible connection part. The piezoelectric film layer comprises a plurality of cantilever beam diaphragms distributed in the same layer. The plurality of cantilever beam diaphragms are all connected to the support body, and a gap is formed between the free ends of at least two cantilever beam diaphragms. The flexible connection part is located at the gap and is respectively connected to the free ends of the at least two cantilever beam diaphragms forming the gap. The flexible connection part satisfies: d∝A 3 / E, where d is the deformation at the center of the flexible connection, A is the ratio of the width of the flexible connection at the gap to the thickness of the flexible connection, and E is the Young's modulus of the flexible connection. Therefore, by clarifying the multiple parameters that affect the resonant frequency and low-frequency response capability of the acoustic piezoelectric structure, as well as the regulatory relationship between the multiple parameters, it is possible for the acoustic piezoelectric structure to have a relatively suitable low-frequency response capability and resonant frequency when applied to a piezoelectric microphone. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0030] Figure 1 It is a schematic diagram of the structure of a diaphragm with a slit;

[0031] Figure 2 The frequency response comparison diagram of piezoelectric microphones with different slit widths;

[0032] Figure 3 One of the structural schematic diagrams of an acoustic piezoelectric structure provided in an embodiment of the present application;

[0033] Figure 4 A schematic diagram of the force on a flexible connection portion of an acoustic piezoelectric structure provided in an embodiment of the present application;

[0034] Figure 5 A second structural schematic diagram of an acoustic piezoelectric structure provided in an embodiment of the present application;

[0035] Figure 6 A third structural schematic diagram of an acoustic piezoelectric structure provided in an embodiment of the present application;

[0036] Figure 7 A fourth structural schematic diagram of an acoustic piezoelectric structure provided in an embodiment of the present application;

[0037] Figure 8 A top view of an acoustic piezoelectric structure provided in an embodiment of the present application;

[0038] Fig. 9 A schematic diagram of the relationship between d and resonant frequency provided in an embodiment of the present application.

[0039] Icon: 110 - support body; 120 - piezoelectric film layer; 121 - substrate; 122 - electrode layer; 123 - piezoelectric layer; 130 - flexible connection part; 140 - gap. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application described and shown in the drawings here can be arranged and designed in various different configurations.

[0041] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the present application for protection, but merely represents selected embodiments of the present application. It should be noted that, in the absence of conflict, the various features in the embodiments of the present application can be combined with each other, and the combined embodiments are still within the scope of protection of the present application.

[0042] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the product of the application is usually placed when in use. They are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0043] In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0044] Please refer to Figure 1 , shows a diaphragm 1 with a slit, the diaphragm 1 can produce more free vibration under the action of sound waves by using the slit 3, so as to have better response sensitivity. However, due to the existence of the slit 3, the ability of the diaphragm 1 in capturing and reproducing low-frequency sounds is affected.

[0045] Specifically, please refer to Figure 2 , Figure 2 The figure is a comparison of the frequency responses of piezoelectric microphones with different slit widths, and the figure shows the frequency response curves of slit 3 widths w of 1μm, 1.2μm, 1.4μm, 1.6μm, 1.8μm and 2μm respectively. It can be seen from the figure that in the low frequency band, the piezoelectric microphone with a smaller slit 3 width w has less signal attenuation. For example, at a frequency of 100Hz, the signal attenuation of piezoelectric microphones with slit widths w of 1μm, 1.2μm, 1.4μm, 1.6μm, 1.8μm and 2μm gradually increases, among which the piezoelectric microphone with a slit 3 width w of 1μm has the smallest signal attenuation and has the highest response signal, while the piezoelectric microphone with a slit 3 width w of 2μm has the largest signal attenuation and has the lowest response signal, and the piezoelectric microphone with a slit 3 width w of 2μm has a slit 3 width doubled compared to the piezoelectric microphone with a slit 3 width w of 1μm, and the response signal of the piezoelectric microphone is attenuated more than ten times.

[0046] Based on the above description, it can be seen that in terms of improving the low-frequency response capability of the piezoelectric microphone, the slit width should be as small as possible. However, it should be understood that, on the one hand, due to the limitation of processing capability, the slit width cannot be very small, and therefore cannot meet the device's requirements for low-frequency response. On the other hand, the slit cannot disappear completely, otherwise a complete diaphragm will cause the resonant frequency to increase significantly and the sensitivity to decrease significantly.

[0047] According to one aspect of an embodiment of the present application, an acoustic piezoelectric structure is provided. By clarifying multiple parameters that affect the resonant frequency and low-frequency response capability of the acoustic piezoelectric structure, as well as the regulatory relationship between the multiple parameters, it is possible for the acoustic piezoelectric structure to have relatively suitable low-frequency response capability and resonant frequency when applied to a piezoelectric microphone.

[0048] In order to better understand the technical solution of the present application, the implementation methods of the present application will be described below in conjunction with the accompanying drawings.

[0049] Please refer to Figure 3 , shows an acoustic piezoelectric structure, which includes a support body 110, a piezoelectric film layer 120 and a flexible connection part 130. Specifically:

[0050] The support body 110 can serve as a basis for supporting the piezoelectric film layer 120. As a possible implementation, Figure 3 As shown, the support body 110 may have a back cavity that runs through the entire thickness direction thereof, so that it is convenient for the subsequent piezoelectric film layer 120 to be suspended in the air, and it is also convenient for the sound waves to directly act on the piezoelectric film layer 120 through the back cavity.

[0051] The piezoelectric film layer 120 includes a plurality of cantilever beam diaphragms distributed in the same layer. Each cantilever beam diaphragm has a fixed end and a free end, wherein each cantilever beam diaphragm is connected to the support body 110 through its own fixed end, and each cantilever beam diaphragm is suspended in the air through its own free end. Among the plurality of cantilever beam diaphragms, there should be at least two cantilever beam diaphragms between which a gap 140 can be formed, and the gap 140 is similar to the aforementioned slit.

[0052] As a possible implementation, the number of the piezoelectric film layer 120 may be one layer or more layers (two layers or more). When the number of the piezoelectric film layer 120 is multiple layers, the piezoelectric film layer 120 may be spaced apart along the thickness direction of the piezoelectric film layer 120 .

[0053] As a possible implementation, the piezoelectric film layer 120 may include a single piezoelectric layer, a double piezoelectric layer, a triple piezoelectric layer, and other structural forms, wherein electrode layers (also referred to as upper electrodes and lower electrodes) are disposed on opposite sides of each piezoelectric layer 123. Figure 3 As shown, the piezoelectric film layer 120 is in the structural form of a single piezoelectric layer 123, that is, the piezoelectric film layer 120 includes a piezoelectric layer 123 and an electrode layer 122 disposed on the upper and lower surfaces of the piezoelectric layer 123. For another example, the piezoelectric film layer 120 is in the structural form of a double piezoelectric layer 123, that is, the piezoelectric film layer 120 includes an electrode layer 122, a piezoelectric layer 123, an electrode layer 122, a piezoelectric layer 123 and an electrode layer 122 stacked in sequence. In addition, a substrate 121 may be provided on the side of the bottom electrode layer 122 away from the piezoelectric layer 123. Based on this, when sound waves act on the piezoelectric film layer 120, the piezoelectric film layer 120 will start to vibrate under the action of the sound pressure and generate corresponding strain. At this time, the piezoelectric layer 123 in the piezoelectric film layer 120 generates charges on its upper and lower sides due to the strain, and is output as an electrical signal through the electrode layer 122.

[0054] The flexible connection part 130 is located at the gap 140. It should be understood that when the number of gaps 140 is two or more, a flexible connection part 130 may be provided at at least one gap 140. Of course, a flexible connection part 130 may also be provided at each gap 140. In addition, two or more cantilever beam diaphragms may constitute the same gap 140. In this case, the same flexible connection part 130 may simultaneously connect all the cantilever beam diaphragms constituting the gap 140.

[0055] When a flexible connection part 130 is provided at the gap 140, the flexible connection part 130 should be connected to the free ends of the two cantilever beam diaphragms forming the gap 140, respectively, so that the gap 140 can be blocked or sealed to a certain extent by the flexible connection part 130, with the purpose of improving the device's response capability to low frequencies. It should be understood here that the flexible connection part 130 has a lower Young's modulus, for example, the Young's modulus of the flexible connection part 130 should be smaller than the Young's modulus of the cantilever beam diaphragm, so that the flexible connection part 130 can be softer than the material of the piezoelectric film layer 120, the silicon material (for example, the material of the substrate 121 is silicon material, or when a supporting layer is provided under the piezoelectric film layer 120, the material of the supporting layer can also be silicon, silicon oxide, etc.), so as to facilitate the formation of a flexible connection between the cantilever beam diaphragms, rather than a rigid connection, so as to minimize the suppression of the vibration of the cantilever beam diaphragm caused by the flexible connection part 130.

[0056] However, in actual application, the flexible connection part 130 needs to consider its applicability to the acoustic piezoelectric structure, so the material selection of the flexible connection part 130 is relatively limited, and basically has a high Young's modulus. For example, the material of the flexible connection part 130 is most commonly used polymer materials such as polyimide, parylene, polymethyl methacrylate (PMMA), SU-8, etc. Therefore, when the cantilever beam diaphragm vibrates under the action of sound pressure, it will still be greatly suppressed and cannot obtain a better improvement effect. For example: an acoustic piezoelectric structure is provided, the thickness of the piezoelectric film layer 120 of which is 1 μm, the length of the cantilever beam diaphragm is 500 μm, the width of the gap 140 is 1 μm, and the material of the flexible connection part 130 is polyimide (Young's modulus is 3 GPa, which is much smaller than the Young's modulus of silicon 170 GPa). For better comparison, a first comparison acoustic piezoelectric structure and a second comparison acoustic piezoelectric structure are respectively set. The main difference between the two and the aforementioned acoustic piezoelectric structure is that the first comparison acoustic piezoelectric structure does not have a flexible connection part 130 at the gap 140, and the second comparison acoustic piezoelectric structure is a rigid connection. The simulation results are obtained by simulating the three acoustic piezoelectric structures:

[0057] Simulation results of the acoustic piezoelectric structure (with a flexible connection portion 130): the resonant frequency is 8.8 kHz, and the displacement deformation (1 kHz / 1 Pa) at the tip / center of the piezoelectric film layer 120 is 0.2 μm;

[0058] The simulation results of the first control acoustic piezoelectric structure (without the flexible connection part 130) are as follows: the resonance frequency is 5.6kHz, and the displacement deformation (1kHz / 1Pa) at the tip / center of the piezoelectric film layer is 0.5μm;

[0059] The simulation results of the second control acoustic piezoelectric structure (rigid connection) are as follows: the resonant frequency is 9.1 kHz, and the displacement deformation (1 kHz / 1 Pa) at the center of the piezoelectric film layer is 0.16 μm.

[0060] It can be seen from the above simulation results that the simulation results of the acoustic piezoelectric structure (with a flexible connection 130) are more different from the simulation results of the first control acoustic piezoelectric structure (without a flexible connection 130), while the simulation results of the acoustic piezoelectric structure (with a flexible connection 130) are more similar to the simulation results of the second control acoustic piezoelectric structure (rigid connection). Therefore, the flexible connection of the acoustic piezoelectric structure (with a flexible connection 130) can have a very small improvement compared with the second control acoustic piezoelectric structure (rigid connection), but there is still a large gap compared with the first control acoustic piezoelectric structure (without a flexible connection 130). Therefore, the improvement effect of the acoustic piezoelectric structure (with a flexible connection 130) is not obvious, and it needs to be further optimized to improve the improvement effect. It can be understood that the tip / center of the piezoelectric film layer mentioned above refers to the maximum displacement under the same conditions.

[0061] Please continue to refer to Figure 3 Through research and analysis, it is found that the width of the flexible connection part 130 at the gap 140 and the thickness of the flexible connection part 130 will have a significant impact on the flexible connection effect of the acoustic piezoelectric structure. Therefore, the width of the flexible connection part 130 at the gap 140 and the thickness of the flexible connection part 130 are used together with the Young's modulus of the front flexible connection part 130 as parameters for adjusting the flexible connection effect of the acoustic piezoelectric structure. It is possible to optimize the flexible connection effect of the acoustic piezoelectric structure from multiple angles, effectively improve its upper limit of optimization, and thus meet the diverse needs in multiple scenarios through flexible regulation. Especially when the material of the flexible connection part 130 is limited, the flexible connection effect of the acoustic piezoelectric structure can be optimized by adjusting other parameters, so that the acoustic piezoelectric structure has a relatively suitable low-frequency response capability and resonance frequency when applied to a piezoelectric microphone.

[0062] For easier understanding, the relationship between the width of the flexible connection portion 130 at the gap 140 and the thickness of the flexible connection portion 130 and the flexible connection effect of the acoustic piezoelectric structure is described as follows:

[0063] When the width of the flexible connection part 130 at the gap 140 is larger, the bending modulus of the flexible connection part 130 is smaller, and the optimization effect of its flexible connection is gradually obvious. Through simulation, it can be seen that the resonant frequency will gradually approach the simulation result of the first control acoustic piezoelectric structure (without the flexible connection part 130).

[0064] When the thickness of the flexible connection part 130 is smaller, the bending modulus of the flexible connection part 130 is smaller, and the optimization effect of its flexible connection becomes gradually obvious. Through simulation, it can be seen that the resonant frequency will gradually approach the simulation result of the first control acoustic piezoelectric structure (without the flexible connection part 130).

[0065] Based on the above description, by regulating the width of the flexible connection part 130 at the gap 140, the thickness of the flexible connection part 130 and the Young's modulus of the flexible connection part 130, the flexible connection effect of the acoustic piezoelectric structure can be adjusted. In the actual regulation process, the regulation relationship between the three can be further refined to provide better guidance for the regulation of the flexible connection effect. Specifically, when the piezoelectric film layer 120 is subjected to an external force, the deformation at the center is simultaneously regulated by the width of the flexible connection part 130 at the gap 140, the thickness of the flexible connection part 130 and the Young's modulus of the flexible connection part 130. Therefore, it can be concluded that:

[0066] d∝F·l 3 / EI, where d is the deformation at the center of the flexible connection, F is the external force, l is the width of the flexible connection at the gap, E is the Young's modulus of the flexible connection, and I is the moment of inertia.

[0067] And I∝h 3 , where h is the thickness of the flexible connection.

[0068] Substituting into the above formula, we can get: d∝F·l 3 / E h 3 .

[0069] That is, the flexible connection satisfies: d∝A 3 / E, wherein d is the deformation at the center of the flexible connection, A is the ratio of the width of the flexible connection at the gap to the thickness of the flexible connection, and E is the Young's modulus of the flexible connection.

[0070] For ease of understanding, the relationship between d and resonant frequency is explained: d is highly correlated with the resonant frequency. Generally, the higher the resonant frequency, the smaller d is. For example Fig. 9 As shown, a schematic diagram of the relationship between d and the resonant frequency is shown, which can be approximately considered to be a linear relationship.

[0071] Please continue to refer to Figure 3 , respectively show the width l of the flexible connection part 130 at the gap 140 and the thickness h of the flexible connection part 130, wherein the width l of the flexible connection part 130 at the gap 140 can also be understood as the width of the gap 140 blocked by it.

[0072] According to the above analysis, A 3The larger the / E value is, the better the flexible connection effect of the acoustic piezoelectric structure will be. Conversely, the stronger the limiting effect of the flexible connection part 130 on the cantilever beam diaphragm will be (the weaker the flexible connection effect will be).

[0073] By adjusting the relationship between the above parameters, a relatively ideal flexible connection effect can be achieved, so that the acoustic piezoelectric structure has a relatively suitable low-frequency response capability and resonance frequency when applied to a piezoelectric microphone.

[0074] In some possible implementations, an acoustic piezoelectric structure is provided, the thickness of the piezoelectric film layer 120 is 1 μm, the length of the cantilever beam diaphragm is 500 μm, the width of the gap 140 is 32 μm, the material of the flexible connection part 130 is Parylene (Young's modulus is 1000 MPa), the width of the flexible connection part 130 is 32 μm, and the thickness of the flexible connection part 130 is 1 μm. Therefore, A 3 / E is 32.768, and the simulation shows that the resonant frequency is 5.69kHz, and the displacement deformation (1kHz / 1Pa) at the tip / center of the piezoelectric film layer 120 is 0.46μm. Compared with the simulation results of the first control acoustic piezoelectric structure (without the flexible connection part 130) and the simulation results of the second control acoustic piezoelectric structure (rigid connection), it can be seen that it is closer to the simulation results of the first control acoustic piezoelectric structure (without the flexible connection part 130), so the flexible connection effect of the acoustic piezoelectric structure can be similar to that of a cantilever beam without the flexible connection part 130.

[0075] In some possible implementations, the resonant frequency of the acoustic piezoelectric structure without the flexible connection portion 130 (i.e., the cantilever beam diaphragms in the device are not connected by the flexible connection portion 130, and the free ends thereof can vibrate freely) is used as a reference. When the optimization effect is that the increase in the resonant frequency does not exceed 50% of the reference, the flexible connection portion 130 satisfies: A 3 / E>0.001MPa -1 .

[0076] In some possible implementations, when the optimization effect is that the resonance frequency increases by no more than 10% of the reference standard, the flexible connection portion 130 satisfies: A 3 / E≥27MPa -1 When the flexible connection portion 130 meets this condition, the flexible connection effect of the acoustic piezoelectric structure of the present application is very close to the reference standard.

[0077] For some possible implementations, please refer to Figure 4As shown, the amplitude of the piezoelectric film layer 120 belongs to the micro-amplitude analysis category (the piezoelectric film layer 120 is mainly in linear deformation within this category, so the flexible connection part 130 presents bending deformation), rather than the large amplitude analysis category (the piezoelectric film layer 120 is mainly in nonlinear deformation within this category, so the flexible connection part 130 presents tensile deformation). Therefore, when the sound wave acts on the piezoelectric film layer 120: the flexible connection part 130 is subjected to X-direction stress and Y-direction stress at the same time, and the stress of the flexible connection part 130 in the thickness direction (Y-direction stress) is linearly related to the amplitude; the stress of the flexible connection part 130 in the direction perpendicular to the thickness (X-direction stress) is linearly related to the amplitude. The large amplitude analysis category is mainly for actuators such as speakers that require large amplitude drive, rather than sensor devices such as piezoelectric microphones.

[0078] In some possible implementations, such as Figure 3 As shown, the flexible connection portion 130 is located in the gap 140 , and the thickness of the flexible connection portion 130 is equal to the thickness of the cantilever beam diaphragm.

[0079] In some possible implementations, such as Figure 5 As shown, the flexible connection portion 130 is located in the gap 140 , and the thickness of the flexible connection portion 130 is smaller than the thickness of the cantilever beam diaphragm.

[0080] In some possible implementations, such as Figure 6 As shown, the flexible connection portion 130 is located outside the gap 140, and the flexible connection portion 130 is located on the top surface of the piezoelectric film layer 120. Figure 6 The coverage area of ​​the flexible connection portion 130 is larger than the gap 140 , and therefore, the width l of the flexible connection portion 130 at the gap 140 is the width of the gap 140 blocked by the flexible connection portion 130 .

[0081] In some possible implementations, such as Figure 7 As shown, the flexible connection portion 130 is located outside the gap 140, and the flexible connection portion 130 is located on the bottom surface of the piezoelectric film layer 120. Figure 7 The coverage area of ​​the flexible connection part 130 is larger than the gap 140 , and therefore, the width of the flexible connection part 130 at the gap 140 is the width of the gap 140 blocked by it.

[0082] In some possible implementations, the flexible connection portion 130 blocks part or all of the gap 140. Figure 8 As shown, the flexible connection portion 130 only closes a portion of the gap 140 .

[0083] In another aspect of the embodiment of the present application, a piezoelectric microphone is provided, comprising an ASIC circuit and any of the above-mentioned acoustic piezoelectric structures, wherein the acoustic piezoelectric structure and the ASIC circuit are connected. In this way, the electrical signal output by the electrode layer of the acoustic piezoelectric structure can be processed by the ASIC circuit. By applying the acoustic piezoelectric structure to the piezoelectric microphone, the piezoelectric microphone can have the effect of the above-mentioned acoustic piezoelectric structure, which will not be described in detail here.

[0084] In some possible implementations, the piezoelectric microphone further includes: a substrate and a cover, wherein the acoustic piezoelectric structure and the ASIC circuit are both arranged on the substrate, the substrate is provided with an acoustic hole, the acoustic hole corresponds to the piezoelectric film layer of the acoustic piezoelectric structure, the cover is buckled on the substrate, and covers the acoustic piezoelectric structure and the ASIC circuit to provide protection for them.

[0085] Another aspect of the embodiments of the present application provides an electronic device, including a device body and any of the above-mentioned piezoelectric microphones, wherein the piezoelectric microphone is disposed in the device body. By applying the piezoelectric microphone to the electronic device, the electronic device can have the effect of the above-mentioned acoustic piezoelectric structure, which will not be described in detail here.

[0086] The electronic device in the present application may be a smart phone, a wearable product, a sports camera, a digital camera or a computer, etc.

[0087] According to another aspect of the embodiments of the present application, a method for optimizing the performance of an acoustic piezoelectric structure is provided. The acoustic piezoelectric structure includes a plurality of cantilever beam diaphragms distributed in the same layer, a gap is formed between the free ends of at least two cantilever beam diaphragms, and a flexible connecting portion is provided at the gap.

[0088] Methods include:

[0089] S10: Obtaining performance expectations of the acoustic piezoelectric structure.

[0090] S20: Obtaining optimization parameters of the flexible connection part according to the expected performance value and the optimization model of the flexible connection part, wherein the optimization parameters are A 3 / E, A is the ratio of the width of the flexible connection at the gap to the thickness of the flexible connection, E is the Young's modulus of the flexible connection, and the optimization model of the flexible connection is: d∝A 3 / E, where d is the deformation at the center of the flexible connection.

[0091] When optimizing an acoustic piezoelectric structure with a flexible connection, the performance expectation can be flexibly selected according to the needs, which can be understood as the optimized target, that is, the flexible connection effect of the optimized acoustic piezoelectric structure. For example, the aforementioned increase in the resonant frequency does not exceed 50% or 10% of the reference benchmark.

[0092] Then, according to the expected performance value and the optimization model of the flexible connection (d∝A 3 / E) to obtain the optimal parameters of the flexible connection (A 3 / E) is determined, and then the width of the flexible connection at the gap, the thickness of the flexible connection and the Young's modulus of the flexible connection are determined according to actual conditions.

[0093] The performance optimization method of the acoustic piezoelectric structure provided in the present application can be applied to the aforementioned acoustic piezoelectric structure, piezoelectric microphone and electronic device.

[0094] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An acoustic piezoelectric structure, applied to a piezoelectric microphone, characterized in that: include: Support body; A piezoelectric film layer, wherein the piezoelectric film layer includes a plurality of cantilever beam diaphragms distributed in the same layer, wherein the plurality of cantilever beam diaphragms are all connected to the support body, and a gap is formed between free ends of at least two of the cantilever beam diaphragms; A flexible connection portion, the flexible connection portion is located at the gap and is respectively connected to the free ends of at least two cantilever beam diaphragms forming the gap, and the flexible connection portion satisfies: d∝A 3 / E, wherein d is the deformation at the center of the flexible connection, A is the ratio of the width of the flexible connection at the gap to the thickness of the flexible connection, and E is the Young's modulus of the flexible connection.

2. The acoustic piezoelectric structure according to claim 1, characterized in that: The flexible connection part meets the following requirements: A 3 / E>0.001MPa -1 .

3. The acoustic piezoelectric structure according to claim 2, characterized in that: The flexible connection part satisfies: A 3 / E≥27MPa -1 .

4. The acoustic piezoelectric structure according to any one of claims 1 to 3, characterized in that: When the sound wave acts on the piezoelectric film layer: The stress and amplitude of the flexible connection portion in the thickness direction are in a linear relationship; The stress and amplitude of the flexible connection portion in a direction perpendicular to the thickness are in a linear relationship.

5. The acoustic piezoelectric structure according to any one of claims 1 to 3, characterized in that: The flexible connection portion blocks part or all of the gap.

6. The acoustic piezoelectric structure according to any one of claims 1 to 3, characterized in that: The flexible connection portion is located in the gap, and a thickness of the flexible connection portion is less than or equal to a thickness of the cantilever beam diaphragm.

7. The acoustic piezoelectric structure according to any one of claims 1 to 3, characterized in that: The flexible connection portion is located outside the gap, and the flexible connection portion is located on the top surface or the bottom surface of the piezoelectric film layer.

8. A piezoelectric microphone, characterized in that: The device comprises an ASIC circuit and the acoustic piezoelectric structure according to any one of claims 1 to 7, wherein the acoustic piezoelectric structure is connected to the ASIC circuit.

9. An electronic device, characterized in that: The invention comprises a device body and the piezoelectric microphone as claimed in claim 8, wherein the piezoelectric microphone is arranged on the device body.

10. A method for optimizing the performance of an acoustic piezoelectric structure, characterized in that: The acoustic piezoelectric structure comprises a plurality of cantilever beam diaphragms distributed in the same layer, a gap is formed between the free ends of at least two of the cantilever beam diaphragms, and a flexible connecting portion is provided at the gap; The method comprises: Obtaining an expected performance value of the acoustic piezoelectric structure; The optimization parameters of the flexible connection part are obtained according to the expected performance value and the optimization model of the flexible connection part, wherein the optimization parameters are A 3 / E, A is the ratio of the width of the flexible connection at the gap to the thickness of the flexible connection, E is the Young's modulus of the flexible connection, and the optimization model of the flexible connection is: d∝A 3 / E, where d is the deformation at the center of the flexible connection.

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