A piezoelectric sensing unit, a piezoelectric microphone and a terminal

Abstract

The application discloses a piezoelectric sensing unit, a piezoelectric microphone and a terminal. The piezoelectric sensing unit comprises a base, an auxiliary layer, a center film, a piezoelectric film and a plurality of cantilevers. The base has a cavity extending along a first direction, and the cavity forms a polygonal opening on a first surface of the base, the polygonal opening having adjacent first and second sides. The auxiliary layer is formed on the first surface of the base, and the auxiliary layer comprises a first auxiliary part located in a region adjacent to the first side of the first surface. The cantilevers are connected to the sides of the polygonal opening one by one, and each cantilever comprises a first end part and a second end part, the first end part is connected to the first auxiliary part, and the connection point of the first end part and the first auxiliary part is located on one side of the first auxiliary part close to the second side. The cantilever extends along the extension direction of the second side. The second end part of each cantilever is connected to the center film. In the scheme, the length of the cantilever is relatively long, which is beneficial to improving the signal-to-noise ratio of the piezoelectric microphone.

Description

Technical Field

[0001] This application relates to the field of microphone structure technology, and in particular to a piezoelectric sensing unit, a piezoelectric microphone, and a terminal. Background Technology

[0002] A microphone is a common sound capture device used to convert sound signals into electrical signals. Microphones can be categorized into dynamic, ribbon, electret (ECM), microelectromechanical system (MEMS) condenser, and MEMS piezoelectric types. Modern microphones are predominantly electret and MEMS condenser types; however, due to manufacturing limitations, electret microphones are far less consistent in production and temperature stability than MEMS condenser microphones. Furthermore, MEMS condenser microphones require charge pumps to enhance sensitivity, resulting in higher power consumption. In contrast, MEMS piezoelectric microphones can convert sound pressure into electrical charge output using the positive piezoelectric effect of piezoelectric materials, resulting in lower power consumption.

[0003] Existing piezoelectric microphones include a base with a cavity, a cantilever fabricated in the cavity region of the base, and a piezoelectric material layer fabricated on the cantilever to form the piezoelectric sensing unit of the microphone. In existing piezoelectric microphones, the cantilever typically extends from the edge of the cavity towards the center, or from the center of the cavity towards the edge, resulting in a relatively short cantilever length. The relationship between the microphone's charge output and the pressure applied to the cantilever is strongly correlated with the cantilever length; therefore, the short cantilever length in existing piezoelectric microphones leads to poor charge output performance. Summary of the Invention

[0004] This application provides a piezoelectric induction unit, a piezoelectric microphone, and a terminal to improve the signal-to-noise ratio and performance of the piezoelectric microphone.

[0005] In a first aspect, this application provides a piezoelectric sensing unit. The piezoelectric sensing unit includes a base, an auxiliary layer, a central membrane, a piezoelectric membrane, and multiple cantilever arms. The base has a cavity extending along a first direction, and the cavity forms a polygonal opening on a first surface of the base. The polygonal opening has adjacent first and second sides. The auxiliary layer is formed on the first surface of the base and includes a first auxiliary portion located on the first surface adjacent to the first side. Each cantilever arm is connected to a side of the polygonal opening. Specifically, each cantilever arm includes a first end and a second end. The first end is connected to the first auxiliary portion, and the connection point between the first end and the first auxiliary portion is located on the side of the first auxiliary portion closer to the second side. Since the cantilever arms extend along the extension direction of the second side, the cantilever arms are relatively long, which is beneficial for improving the signal-to-noise ratio of the piezoelectric microphone. The central membrane is connected to the second end of each cantilever arm, and the orthographic projection of the polygonal opening onto a first plane completely covers the orthographic projection of the central membrane onto the first plane, which is perpendicular to the first direction. With the central membrane facing the cavity of the base, sound waves entering the cavity can drive the central membrane to vibrate, thereby driving the cantilever to swing. A piezoelectric membrane is disposed on the surface of the cantilever. Specifically, the piezoelectric membrane includes a piezoelectric material layer, a first electrode layer, and a second electrode layer. The piezoelectric material layer is connected to the first electrode layer and the second electrode layer. Thus, the piezoelectric membrane can convert the swing of the cantilever into an electrical signal.

[0006] The aforementioned cantilever includes a first edge and a second edge, and the first edge and the second edge are connected between a first end and a second end. At least one of the first edge and the second edge is parallel to a second side of the polygon.

[0007] In the specific fabrication of the piezoelectric sensing unit, one possible implementation is to integrate the central membrane and the cantilever into a single, integrally formed structure. This approach simplifies the fabrication process of the piezoelectric sensing unit and also improves the reliability of the connection between the central membrane and the cantilever.

[0008] The aforementioned central diaphragm may have openings. Of course, the number and shape of these openings are not limited. The openings in the central diaphragm can release some sound pressure, thereby increasing the acoustic overload point of the piezoelectric sensing unit.

[0009] When specifically configuring the central membrane and cantilever, they can be located on the same plane or on different planes. When the central membrane and cantilever are on different planes, the central membrane can be located on the side of the cantilever facing the base, and connected to the cantilever via a connecting part. In this design, the piezoelectric sensing unit has high sensitivity, and the piezoelectric microphone with this unit also performs well.

[0010] Since the central diaphragm and the cantilever are set on different planes, at least a part of the structure of the central diaphragm can overlap with the cantilever, which can make the area of ​​the central diaphragm larger, thereby increasing the effective input sound pressure and improving the performance of the piezoelectric microphone.

[0011] The aforementioned connecting portion may specifically include a first connecting portion and a second connecting portion. The first connecting portion may be integrally formed with the cantilever, and the second connecting portion connects the first connecting portion and the central membrane. This solution can improve the connection strength between the central membrane and the cantilever, and extend the service life of the piezoelectric sensing unit.

[0012] In implementing the connection between the first connecting part and the second connecting part, the first connecting part can have multiple first connecting holes, and the second connecting part can be connected to the aforementioned first connecting holes. This improves the reliability of the connection between the first connecting part and the second connecting part.

[0013] Furthermore, the aforementioned second connecting portion can also be connected to the cantilever, thereby connecting the central membrane to the cantilever. Specifically, the cantilever can include at least one second connecting hole, and the aforementioned second connecting portion connects to the second connecting hole. This solution can improve the strength of the connection between the central membrane and the cantilever, and also facilitates the central membrane being in an deployed state.

[0014] When the first edge and the second edge of the cantilever are not parallel, the width of the cantilever along the direction perpendicular to the second edge can be a first width. This first width gradually decreases from the first end to the second end. In this design, the width at the connection between the cantilever and the first auxiliary part is larger, resulting in greater stress near the first end of the cantilever. This is beneficial for converting the vibrations generated by sound waves into electrical signals, improving signal conversion efficiency. Furthermore, the smaller first width at the second end allows for a larger design area for the central diaphragm, increasing the effective input sound pressure and improving the performance of the piezoelectric microphone.

[0015] The first edge and / or the second edge of the aforementioned cantilever are perpendicular to the first side to which the cantilever is connected. That is, if at least one of the first edge and the second edge is perpendicular to the first side, the arrangement can make the cantilever perpendicular to the first side, thereby reducing the torque at the root of the cantilever.

[0016] To achieve a vertical connection between the cantilever and the first side, the first side of the inner cavity of the base can have a groove or protrusion corresponding to the cantilever. It is worth noting that the first side can have a groove, which helps to increase the length of the cantilever.

[0017] The effective area of ​​the piezoelectric film is located on the side of the cantilever close to the first auxiliary part connected to the cantilever. Because the stress in the area where the cantilever connects to the first auxiliary part is relatively high, signal conversion efficiency can be improved, thus enhancing the performance of the piezoelectric microphone.

[0018] The aforementioned central membrane may also have an additional mass block, which can make the central membrane swing larger when subjected to sound pressure, thereby improving the sensitivity of the piezoelectric sensing unit.

[0019] In optional technical solutions, the lengths of the multiple cantilevers of the piezoelectric sensing unit can be the same or different, and this application does not impose any limitations. The multiple cantilevers have different lengths. When the lengths of the multiple cantilevers are different, the piezoelectric microphone can have different low-frequency resonant points, resulting in higher low-frequency sensitivity, thereby improving the voiceprint recognition capability.

[0020] In the optional technical solutions, the material of the cantilever is not limited. In one solution, the material of the cantilever can be different from that of the piezoelectric material layer, serving merely as a structural layer and comprising only one piezoelectric material layer. In this case, the piezoelectric sensing unit is a single-layer piezoelectric cantilever beam (unimorph) mode piezoelectric sensing unit. In another solution, the material of the cantilever can also be the same as that of the piezoelectric material layer, meaning that the cantilever itself also functions as a piezoelectric material layer. In this case, the piezoelectric sensing unit is a double-layer piezoelectric cantilever beam (bimorph) mode piezoelectric sensing unit.

[0021] In the fabrication of the piezoelectric microphone described above, the auxiliary layer and the cantilever can be integrally molded. This facilitates the fabrication of the auxiliary layer and the cantilever, simplifying the manufacturing process. Furthermore, it improves the reliability of the connection between the auxiliary layer and the cantilever.

[0022] Secondly, this application also provides a piezoelectric microphone, which includes a circuit board, a chip, and the piezoelectric sensing unit described in the first aspect. The chip is disposed on the circuit board, and a first electrode, a second electrode, and the chip are connected, thereby enabling the processing of electrical signals converted from sound waves by the piezoelectric sensing unit.

[0023] In an optional technical solution, the piezoelectric microphone also includes a housing, inside which the circuit board, chip, and piezoelectric sensing unit are housed. This housing protects the internal circuit board, chip, and piezoelectric sensing unit and also shields against interference.

[0024] Thirdly, this application also provides a terminal that includes the piezoelectric microphone described in the second aspect above. This terminal has good sound pickup performance. The specific type of the terminal is not limited; for example, it can be a mobile phone, headset, smart device, voice recorder, hearing aid, microphone, voice control device, or in-vehicle voice interaction device, or any other terminal that needs to record sound. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of a piezoelectric microphone in one embodiment of this application;

[0026] Figure 2This is a schematic diagram of another structure of the piezoelectric microphone in the embodiments of this application;

[0027] Figure 3 This is a top view of one of the piezoelectric sensing units in the embodiments of this application;

[0028] Figure 4 This is a side cross-sectional view of a piezoelectric sensing unit in an embodiment of this application;

[0029] Figure 5 This is a top view schematic diagram of another piezoelectric sensing unit in the embodiments of this application;

[0030] Figure 6 This is a top view schematic diagram of another piezoelectric sensing unit in the embodiments of this application;

[0031] Figure 7 This is a top view schematic diagram of another piezoelectric sensing unit in an embodiment of this application;

[0032] Figure 8 This is a schematic diagram of another side cross-sectional view of the piezoelectric sensing unit in an embodiment of this application;

[0033] Figure 9 This is a schematic diagram of another side cross-sectional view of the piezoelectric sensing unit in an embodiment of this application;

[0034] Figure 10 This is a top view schematic diagram of another piezoelectric sensing unit in an embodiment of this application;

[0035] Figure 11 This is a schematic diagram of another side cross-sectional view of the piezoelectric sensing unit in an embodiment of this application;

[0036] Figure 12 This is a top view schematic diagram of another piezoelectric sensing unit in an embodiment of this application;

[0037] Figure 13 This is a schematic diagram of another side cross-sectional view of the piezoelectric sensing unit in an embodiment of this application;

[0038] Figure 14 This is a schematic diagram of another side cross-sectional view of the piezoelectric sensing unit in an embodiment of this application;

[0039] Figure 15 This is a schematic diagram of another side cross-sectional view of the piezoelectric sensing unit in an embodiment of this application.

[0040] Figure label:

[0041] 1-Circuit board; 2-Chip;

[0042] 3-Piezoelectric induction unit; 31-Base;

[0043] 311 - Cavity; 312 - First surface;

[0044] 313 - Polygonal opening; 3131 - First side;

[0045] 3132 - Second side; 3133 - Groove;

[0046] 32-Cantilever; 321-First end;

[0047] 322 - Second end; 323 - First edge;

[0048] 324 - Second edge; 325 - Second connecting hole;

[0049] 33 - Piezoelectric film; 331 - Piezoelectric material layer;

[0050] 332 - First electrode layer; 333 - Second electrode layer;

[0051] 334 - Effective working area; 34 - First electrode;

[0052] 35 - Second electrode; 36 - Auxiliary layer;

[0053] 361 - First auxiliary section; 37 - Central membrane;

[0054] 371 - Opening; 372 - Additional mass block;

[0055] 38-Connecting part; 381-First connecting part;

[0056] 3811 - First connecting hole; 382 - Second connecting part;

[0057] 4-Outer shell. Detailed Implementation

[0058] For ease of understanding, this application provides a piezoelectric induction unit, a piezoelectric microphone, and a terminal. The following describes their application scenarios. Microphones, as commonly used sound capture devices, are currently used in various terminals to achieve functions such as call processing or voice control. The types of microphones are also gradually changing. MEMS piezoelectric microphones, due to their low power consumption, are an important research direction for those skilled in the art. The cantilever of existing piezoelectric microphones typically extends from the edge of the cavity towards the center, or from the center of the cavity towards the edge, resulting in a short cantilever length. The relationship between the microphone's charge output and the pressure on the cantilever is strongly correlated with the cantilever length. Therefore, the short cantilever length of existing piezoelectric microphones leads to poor charge output performance.

[0059] The embodiments of this application will now be described in detail with reference to the accompanying drawings. The terminology used in the following embodiments is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. As used in the specification and appended claims of this application, the singular expressions “a,” “an,” “the,” “the,” “the,” and “this” are intended to also include expressions such as “one or more,” unless the context clearly indicates otherwise.

[0060] References to “an embodiment” or “a specific embodiment” as used in this specification mean that one or more embodiments of this application include a particular feature, structure, or characteristic described in connection with that embodiment. The terms “comprising,” “including,” “having,” and variations thereof mean “including, but not limited to,” unless otherwise specifically emphasized.

[0061] This application provides a terminal that includes a piezoelectric microphone for recording sound. The specific type of the terminal is not limited; for example, it can be a mobile phone, headset, smart device, voice recorder, hearing aid, microphone, voice control device, or in-vehicle voice interaction device, or any other terminal that requires sound recording.

[0062] Figure 1 This is a schematic diagram of a piezoelectric microphone in one embodiment of this application, such as... Figure 1 As shown, the piezoelectric microphone in this embodiment includes a circuit board 1, a chip 2, and a piezoelectric sensing unit 3. The chip 2 is disposed on the circuit board 1; specifically, the chip 2 can be electrically connected to the circuit board 1. The piezoelectric sensing unit 3 includes a base 31, a cantilever 32 formed on the base 31, and a piezoelectric diaphragm (not shown). The base 31 has a cavity 311. The first end 321 of the cantilever 32 is connected to the base 31 and suspended in the cavity 311. The piezoelectric diaphragm is disposed on the surface of the cantilever 32. The piezoelectric diaphragm can receive the vibration of sound waves and convert it into an electrical signal. The piezoelectric diaphragm of the piezoelectric sensing unit 3 is electrically connected to the chip 2, thereby enabling the chip 2 to process the electrical signal generated after the piezoelectric sensing unit 3 receives the sound waves. For example, the chip 2 can perform acquisition, amplification, filtering, and other processing on the electrical signal, and then output an analog signal or a digital signal. In this scheme, the positive piezoelectric properties of the piezoelectric material layer in the piezoelectric film can be used to convert sound waves into electrical signals without the need for additional drivers. This helps to reduce the size and power consumption of the piezoelectric microphone, and thus extend its usage time, thereby increasing the usage time of the terminal equipped with the piezoelectric microphone.

[0063] Please continue to refer to this. Figure 1The piezoelectric microphone may also include a housing 4. The circuit board 1, chip 2, and piezoelectric sensing unit 3 are disposed inside the housing 4. The housing 4 can shield interference signals and protect the devices disposed inside the housing.

[0064] There are two types of packaging methods for piezoelectric microphones: bottom-opening packaging and top-opening packaging. For example... Figure 1 The piezoelectric microphone in the illustrated embodiment is a bottom-opening packaged piezoelectric microphone, which is suitable for thin products. In this embodiment, the piezoelectric sensing unit 3 and the chip 2 are respectively mounted on the circuit board 1, and the area of ​​the circuit board 1 opposite to the cavity 311 of the piezoelectric sensing unit 3 has an opening, which corresponds to the sound inlet. In this packaging method, it is not necessary to provide an opening in the outer casing 4.

[0065] Figure 2 This is a schematic diagram of another structure of the piezoelectric microphone in an embodiment of this application, as shown below. Figure 2 The piezoelectric microphone in the illustrated embodiment is a top-opening packaged piezoelectric microphone. In this embodiment, the piezoelectric sensing unit 3 and the chip 2 are respectively mounted on the circuit board 1, but the circuit board 1 does not have an opening, while the housing 4 has an opening, and the opening of the housing 4 serves as the sound inlet.

[0066] Figure 3 This is a top view of one embodiment of the piezoelectric sensing unit in this application. Figure 4 This is a side cross-sectional view of one embodiment of the piezoelectric sensing unit in this application. Specifically, the above... Figure 4 for Figure 3 A schematic diagram of the cross-sectional structure at point AA. (See diagram.) Figure 3 and Figure 4As shown, the piezoelectric sensing unit 3 includes a base 31, an auxiliary layer 36, multiple cantilever arms 32, a central membrane 37, and a piezoelectric membrane 33. The base 31 serves as the overall support for the piezoelectric sensing unit 3, and it has a cavity 311 extending along a first direction X. This cavity 311 can form a sound transmission chamber. The cavity 311 can be considered a tubular structure with circumferentially sealed sidewalls and opposing first and second openings. The direction from the first opening to the second opening can be considered the first direction X. The cavity 311 forms a polygonal opening 313 on the first surface 312 of the base 31; or, the base 31 has a polygonal opening 313 on its first surface 312, which is the opening of the cavity 311. The auxiliary layer 36 is formed on the first surface 312 of the base 31 and can be used to connect the multiple cantilever arms 32. Specifically, the polygonal opening 313 can be considered to include adjacent first sides 3131 and second sides 3132. The auxiliary layer 36 includes a first auxiliary portion 361, which is located in the region adjacent to the first side 3131 on the first surface 312 of the base 31. That is, the first auxiliary portion 361 is provided on the first surface 312 of the base 31 corresponding to the first side 3131. The multiple cantilever 32 corresponds one-to-one with the sides of the polygonal opening 313. The cantilever 32 includes opposing first end 321 and second end 322, wherein the first end 321 is connected to the side of the first auxiliary portion 361 near the second side 3132, and the cantilever 32 extends along the extension direction of the second side 3132. The central membrane 37 is connected to the second end 322 of each cantilever 32. When the central membrane 37 receives sound waves, it vibrates, which can drive the cantilever 32 to vibrate. Specifically, the orthographic projection of the polygonal opening 313 on the first plane completely covers the orthographic projection of the central membrane 37 on the first plane, and the first plane is perpendicular to the first direction X. This allows the central membrane 37 to move freely within the cavity 311 of the base 31, facilitating vibration under the drive of sound waves. The piezoelectric membrane 33 is disposed on the surface of the cantilever 32. This piezoelectric membrane 33 includes a piezoelectric material layer 331, a first electrode layer 332, and a second electrode layer 333, with the piezoelectric material layer 331 connecting the first electrode layer 332 and the second electrode layer 333. The piezoelectric material layer 331 possesses piezoelectric properties; when physical deformation occurs, it generates an electric charge, the intensity of which is related to the intensity of the deformation. Therefore, as the cantilever 32 vibrates, the piezoelectric material layer 331 generates an electric charge, which can be transmitted through the first electrode layer 332 and the second electrode layer 333, converting the sound signal into an electrical signal.

[0067] In this embodiment, the first end 321 of the cantilever 32 is connected to the first auxiliary part 361 adjacent to the first side 3131. The specific connection point between the cantilever 32 and the first auxiliary part 361 is close to the direction of the second side 3132, and the cantilever 32 extends along the extension direction of the second side 3132. Therefore, the length of the cantilever 32 can reach a maximum of close to the length of the second side 3132. This scheme can make full use of the space of the opening of the cavity 311, so that the length of the cantilever 32 is relatively long. The piezoelectric sensing unit 3 in this embodiment can be a single piezoelectric layer cantilever beam (Unimorph) mode piezoelectric sensing unit or a double piezoelectric layer cantilever beam (Bimorph) mode piezoelectric sensing unit. The relevant term OPT (SNR∝10 Log(OPT)) for the optimization of the cantilever beam signal-to-noise ratio (SNR) of the two modes is:

[0068]

[0069]

[0070] Where ε is the dielectric constant, tan(θ) is the dielectric loss, and d 31 is the piezoelectric constant, w is the width of cantilever 32, L is the length of cantilever 32, t is the thickness of cantilever 32, and q is the piezoelectric constant. uni This refers to the ratio of structural parameters. It is evident that the aforementioned related term OPT is related to the fifth power of the length of cantilever 32, meaning that the length of cantilever 32 has a significant impact on the signal-to-noise ratio. In this embodiment, with a fixed size for cavity 311, the length of cantilever 32 can be made larger, thereby resulting in a higher signal-to-noise ratio for the piezoelectric microphone.

[0071] Understandably, since multiple cantilever arms 32 correspond one-to-one with the edges of the polygonal opening 313, each edge of the polygonal opening 313 can be understood as the first edge 3131 under different references. Similarly, the regions of the auxiliary layer 36 adjacent to each edge of the polygon also form the first auxiliary portion 361 based on the understanding of the first edge 3131. That is, whichever cantilever arm 32 is used as the reference, the auxiliary layer 36 connected to that cantilever arm 32 is the first auxiliary portion 361, and the edges of the polygon adjacent to the first auxiliary portion 361 are the first edges 3131. In other words, when different cantilever arms 32 are used as references, each edge of the polygonal opening 313 may form the first edge 3131, and the portion of the auxiliary layer 36 opposite to the polygonal opening 313 can be the first auxiliary portion 361.

[0072] like Figure 3As shown, the piezoelectric sensing unit 3 may further include a first electrode 34 and a second electrode 35. The first electrode layer 332 of the piezoelectric film 33 of each cantilever 32 is connected to the first electrode 34, and the second electrode layer 333 of the piezoelectric film 33 of each cantilever 32 is connected to the second electrode 35. It is worth noting that the first electrode layers 332 can be connected in series or in parallel, and the second electrode layers 333 can be connected in series or in parallel. This application does not impose any restrictions on this, and the design can be carried out according to the actual needs of the piezoelectric microphone.

[0073] In optional technical solutions, the piezoelectric sensing unit 3 in this embodiment can be a single-layer piezoelectric cantilever beam (unimorph) mode piezoelectric sensing unit or a double-layer piezoelectric cantilever beam (bimorph) mode piezoelectric sensing unit. When the piezoelectric sensing unit 3 is a unimorph mode piezoelectric sensing unit, the cantilever 32 is a substrate, and the material of the cantilever 32 is different from the material of the piezoelectric material layer, for example, it can be made of a silicon-containing material. In other embodiments, when the piezoelectric sensing unit 4 is a bimorph mode piezoelectric sensing unit, the material of the cantilever 32 is the same as the piezoelectric material layer, that is, the cantilever itself also serves as a piezoelectric material layer. Of course, in some embodiments, the cantilever 32 can also be a substrate, and two piezoelectric material layers can be disposed on the surface of the cantilever to form a bimorph mode piezoelectric sensing unit.

[0074] Please refer to Figure 3 The aforementioned cantilever 32 includes opposing first edges 323 and second edges 324, which are respectively connected between a first end 321 and a second end 322. At least one of the first edges 323 and second edges 324 is parallel to the second side 3132 of the polygonal opening 313. This embodiment allows the length of the cantilever 32 to nearly reach the length of the second side 3132, meaning that the cantilever 32 can be relatively long while occupying less area in the middle region of the polygonal opening 313, resulting in a larger area of ​​the central diaphragm 37, which is beneficial for increasing the effective input sound pressure level. This solution can fully utilize the area of ​​the polygonal opening 313 to improve the performance of the piezoelectric microphone.

[0075] In specific implementation methods, such as Figure 3 As shown, the first edge 323 and the second edge 324 can be made parallel, so that both the first edge 323 and the second edge 324 are parallel to the second edge 3132. Or, as... Figure 5 and Figure 6 As shown, two other top view structural schematic diagrams of the piezoelectric sensing unit are illustrated. In other embodiments, the first edge 323 and the second edge 324 can be made non-parallel, meaning that only the first edge 323 is parallel to the second edge 3132, while the second edge 324 is not parallel to the second edge 3132.

[0076] Please continue to refer to this. Figure 5 When the first edge 323 and the second edge 324 are not parallel, the width of the cantilever 32 along the direction perpendicular to the second edge 3132 is taken as the first width d. This first width d can then gradually increase from the first end 321 to the second end 322 of the cantilever 32. In this design, the width at the connection between the cantilever 32 and the first auxiliary part 361 is relatively small, allowing for more space to be reserved for adjacent cantilever 32s. This is beneficial for increasing the length of the cantilever 32, thereby improving OPT and SNR.

[0077] Please continue to refer to this. Figure 6 When the first edge 323 and the second edge 324 are not parallel, the width of the cantilever 32 along the direction perpendicular to the second edge 3132 is taken as the first width d. This first width d can then gradually decrease from the first end 321 to the second end 322 of the cantilever 32. In this design, the width at the connection between the cantilever 32 and the first auxiliary part 361 is relatively large because the stress near the first end 321 of the cantilever 32 is relatively high. Therefore, this embodiment can make the area of ​​the region with high stress on the cantilever 32 larger, which is beneficial for converting the vibration generated by the sound wave into an electrical signal and improving the signal conversion efficiency. Furthermore, since the first width of the second end 322 is smaller, the area of ​​the central diaphragm 37 can be designed to be larger, which can increase the effective input sound pressure and improve the performance of the piezoelectric microphone.

[0078] Please continue to refer to this. Figures 4 to 6 Specifically, when configuring the cantilever 32, at least one of the first edge 323 and the second edge 324 of the cantilever 32 can be made perpendicular to the first side 3131 connected to the cantilever 32. In this embodiment, the cantilever 32 is perpendicular to the first side 3131, so that during the vibration of the cantilever 32, torque is less likely to occur at the connection between the first end 321 and the first auxiliary part 361, which is beneficial to forming effective charge output.

[0079] Figure 7 This is a top view schematic diagram of another piezoelectric sensing unit in an embodiment of this application. It is worth noting that, for ease of illustrating features, Figure 7 The accompanying drawings have been simplified, showing only the auxiliary layer 36 and the cantilever 32. (See attached diagram.) Figure 7 As shown, since the first side 3131 and the second side 3132 are not necessarily perpendicular, in other words, the polygonal opening is not necessarily a square opening; it may also be a triangular opening, a pentagonal opening, or other polygonal openings. Figure 7The polygonal opening of the piezoelectric sensing unit shown is actually a triangular opening. Therefore, to ensure that at least one of the first edge 323 and the second edge 324 is perpendicular to the first side 3131 connected to the cantilever 32, the first side 3131 can have a protrusion or groove 3133 corresponding to the cantilever 32. That is, the cantilever 32 is connected to the first auxiliary portion 361 corresponding to the aforementioned protrusion and groove 3133, and it is ensured that at least one of the first edge 323 and the second edge 324 is perpendicular to the first side 3131 connected to the cantilever 32. In a preferred embodiment, the first side 3131 can have a groove 3133, which facilitates increasing the length of the cantilever 32.

[0080] Figure 8 This is a schematic diagram of another side cross-sectional view of the piezoelectric sensing unit in an embodiment of this application. For example... Figure 8 As shown, when fabricating the piezoelectric film 33 on the surface of the cantilever 32, the effective working area 334 of the piezoelectric film 33 can be located on the side of the cantilever 32 near the first auxiliary part 361 connected to the cantilever 32. That is, the effective working area 334 of the piezoelectric film 33 is located near the root of the cantilever 32. Since the stress is greater on the side of the cantilever 32 near the first auxiliary part 361 connected to the cantilever 32, locating the effective working area 334 of the piezoelectric film 33 here can improve signal conversion efficiency and enhance the performance of the piezoelectric microphone.

[0081] The aforementioned effective working area 334 refers to the region where the piezoelectric film 33 can convert the deformation of the piezoelectric material layer 331 into an electrical signal. Specifically, it can be the region where the piezoelectric film 33 simultaneously has a first electrode layer 332, a piezoelectric material layer 331, and a second electrode layer 333.

[0082] In a specific implementation, the entire piezoelectric film 33 can be positioned on the side of the cantilever 32 closest to the first auxiliary part 361 connected to the cantilever 32, such as... Figure 6 and Figure 8 As shown. Or, Figure 9 This is a schematic diagram of another side cross-sectional view of the piezoelectric sensing unit in an embodiment of this application. For example... Figure 9 As shown, in another embodiment, at least one of the first electrode layer 332 and the second electrode layer 333 may be disposed on the side of the cantilever 32 near the first auxiliary part 361 connected to the cantilever 32, while the piezoelectric material layer 331 covers the entire cantilever 32. This scheme can simplify the manufacturing process of the piezoelectric film 33.

[0083] Of course, in other embodiments, such as Figure 3 In the embodiments shown, the piezoelectric film 33 may also completely cover the entire cantilever 32, and this application does not limit this.

[0084] The specific fabrication method of the first electrode layer 332 and the second electrode layer 333 is not limited. In one embodiment, such as... Figure 8 and Figure 9 As shown, the first electrode layer 332 and the second electrode layer 333 can be disposed on both sides of the piezoelectric material layer 331, that is, the first electrode layer 332, the piezoelectric material layer 331 and the second electrode layer 333 are stacked sequentially. In another embodiment, the first electrode layer 332 and the second electrode layer 333 are formed as interdigitated electrodes. In a specific embodiment, the first electrode layer 332 and the second electrode layer 333 can be located on the same side surface of the piezoelectric material layer 331. Of course, in other embodiments, the first electrode layer 332, the piezoelectric material layer 331 and the second electrode layer 333 can also be stacked sequentially, indicating that the first electrode layer 332 is an interdigitated structure and the second electrode layer 333 is an interdigitated structure. This application does not limit this.

[0085] Please continue to refer to this. Figures 5 to 7 In the specific fabrication of the auxiliary layer 36 and cantilever 32, the auxiliary layer 36 and cantilever 32 can be integrated into a single structure. This approach simplifies the fabrication process by allowing the auxiliary layer 36 and cantilever 32 to be formed in a single process. Furthermore, it ensures a more reliable connection between the cantilever 32 and the auxiliary layer 36, thereby improving the structural reliability of the piezoelectric sensing unit 3.

[0086] Furthermore, the central membrane 37 and the cantilever 32 can be integrally formed. Similarly, this approach facilitates the fabrication of the central membrane 37 and the cantilever 32, allowing them to be formed in a single process, thus simplifying the fabrication process. On the other hand, it ensures a more reliable connection between the cantilever 32 and the central membrane 37, thereby improving the structural reliability of the piezoelectric sensing unit 3.

[0087] In specific embodiments, the central membrane 37, cantilever 32 and auxiliary layer 36 can be integrally formed, thereby forming the central membrane 37, cantilever 32 and auxiliary layer 36 in a single process, which greatly simplifies the process.

[0088] like Figure 5 and Figure 6 As shown, the central membrane 37 described above may have openings 371. The specific number of openings 371 is not limited. For example, it may be as follows: Figure 5 and Figure 6 As shown, the central membrane 37 has an opening 371. Or, as Figure 3 As shown, the central membrane 37 may also have two or more openings 371. Furthermore, the shape of these openings is not limited and can be circular or square, etc. The openings in this design can release some sound pressure, thereby increasing the acoustic overload point (AOP) of the piezoelectric sensing unit.

[0089] like Figures 5 to 9 In the embodiment shown, the plane where the central membrane 37 is located is the same plane as the plane where the cantilever 32 is located. Figure 10 This is a top view schematic diagram of another piezoelectric sensing unit in an embodiment of this application. Figure 11 This is another side cross-sectional view of the piezoelectric sensing unit in an embodiment of this application. Specifically, Figure 11 for Figure 10 The cross-sectional view of BB. It is worth noting that, for ease of depiction of features, Figure 10 The accompanying drawings have been simplified, illustrating only the technical features that differentiate this embodiment from other embodiments. Please refer to... Figure 10 and Figure 11 In one embodiment, the central membrane 37 is located on the side of the cantilever 32 facing the base 31, and the central membrane 37 is connected to the cantilever 32 via a connecting portion 38. In this solution, the central membrane 37 and the cantilever 32 are located on different planes, resulting in higher sensitivity of the piezoelectric sensing unit 3 and better performance of the piezoelectric microphone with the piezoelectric sensing unit 3.

[0090] Since the central diaphragm 37 and the cantilever 32 are disposed on different planes, at least a portion of the structure of the central diaphragm 37 can overlap with the cantilever 32, thereby increasing the area of ​​the central diaphragm 37, increasing the effective input sound pressure, and improving the performance of the piezoelectric microphone.

[0091] To connect the central membrane 37 to the second end 322 of the cantilever 32, the connecting part 38 can be used to directly connect the central membrane 37 and the second end 322 of the cantilever 32, such as... Figure 10 As shown. Or, Figure 12 This is a top view schematic diagram of another piezoelectric sensing unit in an embodiment of this application. Figure 13 This is a side cross-sectional view of one embodiment of the piezoelectric sensing unit in this application. Please refer to... Figure 12 and Figure 13 Alternatively, the connecting portion 38 can include a first connecting portion 381 and a second connecting portion 382. The first connecting portion 381 and the cantilever 32 are integrally formed, and the second connecting portion 382 connects the first connecting portion 381 and the central membrane 37. This solution helps to improve the connection strength between the central membrane 37 and the cantilever 32, and extends the service life of the piezoelectric sensing unit 3.

[0092] Specifically, the first connecting part 381 includes a plurality of first connecting holes 3811, and the second connecting part 382 is connected to the first connecting holes 3811, which helps to improve the connection strength between the second connecting part 382 and the first connecting part 381.

[0093] Figure 14This is a side cross-sectional view of one embodiment of the piezoelectric sensing unit in this application. Please refer to the diagram. Figure 12 and Figure 14 The cantilever 32 may further include at least one second connecting hole 325, and the second connecting portion 38 is connected to the second connecting hole 325. This design can improve the strength of the connection between the central membrane 37 and the cantilever 32. In particular, when the central membrane 37 has a large area and part of its structure overlaps with the cantilever 32, the connection between the central membrane 37 and the cantilever 32 via the second connecting portion 382 facilitates the deployment of the central membrane 37.

[0094] Figure 15 This is a side cross-sectional view of one embodiment of the piezoelectric sensing unit in this application. Please refer to the diagram. Figure 15 In the specific configuration of the central membrane 37, it can also be equipped with an additional mass block 372. This design allows the central membrane 37 to swing more significantly when subjected to sound pressure, thereby improving the sensitivity of the piezoelectric sensing unit 3.

[0095] In specific embodiments, the lengths of the multiple cantilever 32 of the piezoelectric sensing unit 3 can be the same or different, and this application does not impose any restrictions. When the lengths of the multiple cantilever 32 are different, the piezoelectric microphone can have different low-frequency resonant points, resulting in higher low-frequency sensitivity, thereby improving the voiceprint recognition capability.

[0096] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the scope of protection of this application. Therefore, if such modifications and variations fall within the scope of the claims of this application and their equivalents, this application also intends to include such modifications and variations.

Claims

1. A piezoelectric sensing unit, characterized in that, include: A base having a cavity extending along a first direction, the cavity forming a polygonal opening on a first surface of the base, the polygonal opening including an adjacent first side and a second side; An auxiliary layer is formed on the first surface of the base, the auxiliary layer including a first auxiliary portion located in the region of the first surface adjacent to the first edge; Multiple cantilever arms correspond one-to-one with the sides of the polygonal opening; each cantilever arm includes a first end and a second end opposite to each other, the first end being connected to the side of the first auxiliary part closer to the second side; the cantilever arm extends along the extension direction of the second side; A central membrane, which is connected to the second end of each of the cantilever arms, wherein the orthographic projection of the polygonal opening onto a first plane completely covers the orthographic projection of the central membrane onto the first plane, the first plane being perpendicular to the first direction; A piezoelectric film is disposed on the surface of the cantilever; the piezoelectric film includes a piezoelectric material layer, a first electrode layer and a second electrode layer, wherein the piezoelectric material layer connects the first electrode layer and the second electrode layer.

2. The piezoelectric sensing unit as described in claim 1, characterized in that, The cantilever includes opposing first and second edges, the first edge and / or the second edge being parallel to the second side of the polygonal opening.

3. The piezoelectric sensing unit as described in claim 1 or 2, characterized in that, The central membrane and the cantilever are integrally formed.

4. The piezoelectric sensing unit as described in claim 3, characterized in that, The central membrane has openings.

5. The piezoelectric sensing unit as described in claim 1 or 2, characterized in that, The central membrane is located on the side of the cantilever facing the base, and the central membrane is connected to the cantilever via a connecting part.

6. The piezoelectric sensing unit as described in claim 5, characterized in that, The central membrane has at least a partial structure that overlaps with the cantilever.

7. The piezoelectric sensing unit as described in claim 5, characterized in that, The connecting part includes a first connecting part and a second connecting part. The first connecting part and the cantilever are integrally formed. The second connecting part connects the first connecting part and the central membrane.

8. The piezoelectric sensing unit as described in claim 6, characterized in that, The connecting part includes a first connecting part and a second connecting part. The first connecting part and the cantilever are integrally formed. The second connecting part connects the first connecting part and the central membrane.

9. The piezoelectric sensing unit as described in claim 7 or 8, characterized in that, The first connecting part includes a plurality of first connecting holes, and the second connecting part is connected to the first connecting holes.

10. The piezoelectric sensing unit as described in claim 9, characterized in that, The cantilever includes at least one second connection hole, and the second connection portion is connected to the second connection hole.

11. The piezoelectric sensing unit as described in claim 1 or 2, characterized in that, The width of the cantilever along the direction perpendicular to the second side is the first width, which gradually increases or decreases from the first end to the second end.

12. The piezoelectric sensing unit as described in claim 2, characterized in that, The first edge and / or the second edge of the cantilever are perpendicular to the first side connected to the cantilever.

13. The piezoelectric sensing unit as described in claim 12, characterized in that, The first side of the cavity has a groove or protrusion corresponding to the cantilever.

14. The piezoelectric sensing unit as described in claim 1 or 2, characterized in that, The effective working area of ​​the piezoelectric film is located on the side of the cantilever near the first auxiliary part connected to the cantilever.

15. The piezoelectric sensing unit as described in claim 1 or 2, characterized in that, The central membrane has an additional mass block.

16. The piezoelectric sensing unit as described in claim 1 or 2, characterized in that, The lengths of the various cantilever arms are different.

17. The piezoelectric sensing unit as described in claim 1 or 2, characterized in that, The cantilever is made of the same material as the piezoelectric material layer.

18. The piezoelectric sensing unit as described in claim 1 or 2, characterized in that, The auxiliary layer and the cantilever are integrally formed.

19. A piezoelectric microphone, characterized in that, The device includes a circuit board, a chip, and a piezoelectric sensing unit as described in any one of claims 1 to 18, wherein the chip is disposed on the circuit board, and the first electrode layer and the second electrode layer are connected to the chip.

20. The piezoelectric microphone as claimed in claim 19, characterized in that, It also includes a housing, inside which the circuit board, chip and piezoelectric sensing unit are disposed.

21. A terminal, characterized in that, Including the piezoelectric microphone as described in claim 19 or 20.

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