A sensing device

Abstract

The embodiments of this specification provide a sensor device and microphone. The sensor device includes a housing and a transducer unit. The housing has a chamber within it. The transducer unit includes a vibration pickup structure for picking up housing vibrations and generating an electrical signal. The transducer unit, within the chamber, divides the chamber into a front chamber and a rear chamber located on opposite sides of the vibration pickup structure. At least one of the front and rear chambers is filled with liquid, which contacts the vibration pickup structure, and an air cavity exists between the liquid and the housing.

Description

[0001] Cross-references

[0002] This specification claims priority to Chinese patent application No. 202110445739.3 filed on April 23, 2021, the contents of which are incorporated herein by reference. Technical Field

[0003] This specification relates to electronic devices, and in particular to a sensing device. Background Art

[0004] For a sensing device (such as a microphone), when the frequency of an external vibration signal approaches its natural resonant frequency, it generates a larger amplitude, resulting in a larger electrical signal output. Consequently, the sensing device's response to external vibration exhibits higher sensitivity near the resonant frequency and lower sensitivity at other frequencies (e.g., mid- and low-frequency frequencies), resulting in uneven output gain.

[0005] Therefore, it is desirable to provide a sensing device with flat output gain and high sensitivity over a wider frequency range. Summary of the Invention

[0006] One embodiment of this specification provides a sensor device comprising a housing and a transducer unit. The housing has a chamber therein. The transducer unit includes a vibration pickup structure for picking up housing vibrations and generating an electrical signal. The transducer unit, within the chamber, divides the chamber into a front chamber and a rear chamber located on opposite sides of the vibration pickup structure. At least one of the front and rear chambers is filled with liquid, which contacts the vibration pickup structure, and an air cavity exists between the liquid and the housing.

[0007] One of the embodiments of this specification provides a microphone, which may include the above-mentioned sensing device.

[0008] Some additional features of the present application may be explained in the following description. Some additional features of the present application will be apparent to those skilled in the art from a study of the following description and accompanying drawings, or from understanding the production or operation of the embodiments. Features of the present application may be realized and implemented by practicing or using various aspects of the methods, tools, and combinations described in the detailed examples discussed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] This specification will be further described in the form of exemplary embodiments, which will be described in detail with reference to the accompanying drawings. These embodiments are not limiting, and in these embodiments, like numbers represent like structures, wherein:

[0010] Figure 1 is a schematic diagram of an exemplary sensing device provided according to some embodiments of the present application;

[0011] Figure 2 is a schematic structural diagram of an exemplary microphone provided according to some embodiments of the present application;

[0012] Figure 3 is a schematic diagram of an exemplary equivalent vibration model of a transducer unit provided according to some embodiments of the present application;

[0013] Figure 4 is a schematic diagram of a displacement resonance curve of an exemplary sensing device provided according to some embodiments of the present application;

[0014] Figure 5 is a mechanical equivalent schematic diagram of an exemplary sensing device provided according to some embodiments of the present application;

[0015] Figure 6 is a schematic diagram of a sensing device filled with liquid according to some embodiments of the present application;

[0016] Figure 7 is a mechanical equivalent schematic diagram of an exemplary sensing device provided according to some embodiments of the present application;

[0017] Figure 8 is a schematic diagram of a sensing device filled with liquid and bubbles according to some embodiments of the present application;

[0018] Figure 9 is an exemplary frequency response curve of a sensing device provided according to some embodiments of the present application;

[0019] Figure 10 is an exemplary frequency response curve of a sensing device provided according to some embodiments of the present application;

[0020] Figure 11 is a schematic diagram of a sensing device to be filled with liquid according to some embodiments of the present application;

[0021] Figure 12 is a schematic diagram of an exemplary liquid-filled sensing device provided according to some embodiments of the present application;

[0022] Figure 13 is a frequency response curve of the sensing device before and after being partially filled with liquid according to some embodiments of the present application;

[0023] Figure 14 1 is a frequency response curve of a sensor device with a small-sized accommodating cavity before and after being filled with liquid according to some embodiments of the present application;

[0024] Figure 15 Frequency response curves of a sensing device with a large-sized accommodating cavity provided in some embodiments of the present application when the cavity is not filled with liquid, partially filled with liquid, or when an oil film exists in the accommodating cavity;

[0025] Figure 16 is a schematic diagram of a sensing device filled with liquid and bubbles according to some embodiments of the present application;

[0026] Figure 17 1 is a frequency response curve of a sensing device provided in some embodiments of the present application, wherein the liquid in the accommodating chamber contains bubbles of different sizes;

[0027] Figures 18A-18D is a schematic diagram of a sensing device for bubbles in a filled liquid at different positions according to some embodiments of the present application;

[0028] Figure 19 1 is a frequency response curve of bubbles in a filling liquid at different positions in a receiving chamber of a sensor device according to some embodiments of the present application;

[0029] Figure 20 is a frequency response curve before and after the sensing device is filled with liquid according to some embodiments of the present application;

[0030] Figure 21 is a schematic diagram of an exemplary sensing device including a droplet according to some embodiments of the present application;

[0031] Figure 22 is a schematic diagram of an exemplary sensing device including a droplet according to some embodiments of the present application;

[0032] Figures 23A-23B is a schematic diagram of an exemplary sensing device including a liquid film according to some embodiments of the present application;

[0033] Figures 24A-24B is a schematic diagram of an exemplary sensing device including a liquid film according to some embodiments of the present application;

[0034] Figure 25A is a schematic diagram of the mechanical structure of an exemplary sensing device according to some embodiments of the present application;

[0035] Figures 25B-25D is a schematic structural diagram of an exemplary sensing device according to some embodiments of the present application;

[0036] Figure 26 is a schematic top view of an exemplary transducer unit according to some embodiments of the present application;

[0037] Figures 27A-27D yes Figure 26 AA cross-sectional diagram of the middle transducer unit;

[0038] Figure 28Ais a schematic structural diagram of an exemplary sensing device according to some embodiments of the present application;

[0039] Figure 28B yes Figure 28A A top view of the middle transducer unit;

[0040] Figures 29A-29C is a frequency response curve of an exemplary sensing device according to some embodiments of the present application;

[0041] Figures 30A-30B is a schematic structural diagram of an exemplary sensing device according to some embodiments of the present application;

[0042] Figure 31 is a frequency response curve of an exemplary sensing device including a capacitive transducer according to some embodiments of the present application;

[0043] Figure 32 is a schematic structural diagram of an exemplary sensing device according to some embodiments of the present application;

[0044] Figure 33 is a schematic structural diagram of an exemplary sensing device according to some embodiments of the present application;

[0045] Figure 34 is a schematic structural diagram of an exemplary sensing device according to some embodiments of the present application;

[0046] Figure 35A is a frequency response curve of an exemplary sensing device including a gas cavity according to some embodiments of the present application;

[0047] Figure 35B is a frequency response curve of an exemplary sensing device according to some embodiments of the present application;

[0048] Figure 36 is a schematic top view of an exemplary sensor device according to some embodiments of the present application;

[0049] Figure 37 is a schematic structural diagram of an exemplary sensing device according to some embodiments of the present application;

[0050] Figure 38 is a frequency response curve of an exemplary sensor device provided with liquid according to some embodiments of the present application;

[0051] Figure 39 is a frequency response curve of an exemplary sensor device provided with liquid according to some embodiments of the present application;

[0052] Figure 40 is a schematic diagram of an exemplary structure of an air conduction microphone provided according to some embodiments of the present application;

[0053] Figure 41 is a schematic diagram of a sensing device provided according to some embodiments of the present application;

[0054] Figure 42 1 is a frequency response curve of an air conduction microphone before and after being filled with liquid according to some embodiments of the present application;

[0055] Figure 43 is a schematic diagram of a sensing device provided according to some embodiments of the present application;

[0056] Figure 44 1 is a frequency response curve of a sensing device filled with liquids of different kinematic viscosities provided in accordance with some embodiments of the present application;

[0057] Figure 45 is an exemplary schematic diagram of a sensing device provided according to some embodiments of the present application

[0058] Figure 46 1 is a frequency response curve of a sensing device filled with liquids of different viscosities according to some embodiments of the present application;

[0059] Figure 47 is a schematic diagram of an exemplary sensing device provided according to some embodiments of the present application;

[0060] Figure 48 is a schematic diagram of an exemplary gyroscope according to some embodiments of the present application;

[0061] Figure 49 is a schematic diagram of an exemplary test sensing device sensitivity according to some embodiments of the present application. DETAILED DESCRIPTION

[0062] To more clearly illustrate the technical solutions of the embodiments of this specification, the following briefly describes the drawings required for describing the embodiments. Obviously, the drawings described below are merely examples or embodiments of this specification. Those skilled in the art can apply this specification to other similar scenarios based on these drawings without inventive effort. Unless otherwise apparent from the context or otherwise noted, the same reference numerals in the figures represent the same structure or operation.

[0063] It should be understood that the terms "system," "device," "unit," and / or "module" used herein are a method for distinguishing different components, elements, parts, portions, or assemblies at different levels. However, if other terms can achieve the same purpose, the terms may be replaced by other expressions.

[0064] As used in this specification and claims, unless the context clearly indicates otherwise, the words "a," "an," "an," and / or "the" do not refer to the singular but also include the plural. Generally speaking, the terms "comprises" and "include" only indicate the inclusion of the steps and elements specifically identified, and these steps and elements do not constitute an exclusive list. A method or apparatus may also include other steps or elements.

[0065] In the description of this specification, it should be understood that the terms "first," "second," "third," "fourth," etc. are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature defined as "first," "second," "third," or "fourth" may explicitly or implicitly include at least one of such features. In the description of this specification, "plurality" means at least two, for example, two, three, etc., unless otherwise specifically defined.

[0066] In this specification, unless otherwise specified or limited, terms such as "connected" and "fixed" should be interpreted broadly. For example, the term "connected" can refer to a fixed connection, a removable connection, or an integral connection; a mechanical connection or an electrical connection; a direct connection or an indirect connection through an intermediate medium; and can refer to internal communication between two components or an interaction between two components, unless otherwise specified. Those skilled in the art will understand the specific meanings of these terms in this specification based on the specific circumstances.

[0067] A sensing device is provided in an embodiment of the present specification. The sensing device can convert an external signal (for example, a sound signal, a vibration signal, a pressure signal) into a target signal (for example, an electrical signal). The sensing device may include a shell and a transducer unit. The shell has an interior containing a cavity, and the transducer unit includes a vibration pickup structure for picking up the vibration of the shell and generating an electrical signal. The transducer unit can separate the accommodating cavity into a front cavity and a rear cavity located on opposite sides of the vibration pickup structure within the accommodating cavity. At least one of the front cavity and the rear cavity is filled with liquid, and the liquid is in contact with the vibration pickup structure.

[0068] In some embodiments, the vibration pickup structure may have a resonant frequency (e.g., a first resonant frequency), which is related to the properties of the vibration pickup structure itself (e.g., shape, material, structure, etc.). In some embodiments, an air cavity may exist in the front cavity and / or rear cavity filled with liquid. The air cavity may change volume as the liquid vibrates. The liquid and / or air cavity in the front cavity and / or rear cavity may work together to affect the response of the sensing device to external signals, which may form an additional resonant system and provide the sensing device with an additional resonant frequency (e.g., a second resonant frequency), thereby making the frequency response curve of the sensing device (which may be referred to as a frequency response curve for short) flatter. In some embodiments, the air cavity may exist inside the liquid (e.g., in the form of bubbles). In some embodiments, in order to facilitate the preparation of the sensing device and improve the stability of the sensing device, the air cavity may be located between the liquid and the shell. Furthermore, a first flexible membrane may be provided between the liquid and the air cavity.

[0069] In some embodiments, when only one of the front cavity and the rear cavity is filled with liquid, the resonant frequency (e.g., the first resonant frequency) of the sensing device can be adjusted by adjusting the equivalent stiffness of the gas in the other cavity that is not filled with liquid. For example, an air hole can be provided at a shell position corresponding to the other cavity that is not filled with liquid to reduce the equivalent stiffness of the gas in the cavity, thereby moving the resonant frequency (i.e., the first resonant frequency) of the vibration pickup structure and / or the additional resonant peak of the additional resonant system toward a low frequency direction. For another example, the equivalent stiffness of the gas can be changed by changing the gas pressure of the gas in the other cavity that is not filled with liquid, thereby adjusting the position of the first resonant peak and / or the additional resonant peak. For another example, the position of the first resonant peak and / or the additional resonant peak can be adjusted by changing the cavity size of the other cavity that is not filled with liquid.

[0070] In this way, by adjusting the parameters of the vibration pickup structure and / or the additional resonant system (such as the air cavity size, liquid mass, liquid viscosity, etc.), the relationship between the first resonant frequency and the second resonant frequency can be changed, thereby achieving, for example, improving the sensitivity and reliability of the sensing device in a wider frequency range (especially the mid- and low-frequency range) or making the output gain of the sensing device flatter in the required frequency band (for example, mid- and low-frequency).

[0071] Figure 1 is a schematic diagram of an exemplary sensing device provided according to some embodiments of the present application.

[0072] The sensing device 100 can generate deformation and / or displacement based on external signals, such as mechanical signals (such as pressure, mechanical vibration), acoustic signals (such as sound waves), electrical signals, optical signals, thermal signals, etc. The deformation and / or displacement can be further converted into a target signal by the transducer component of the sensing device 100. In some embodiments, the target signal can be an electrical signal, a mechanical signal (such as mechanical vibration), an acoustic signal (such as sound waves), an electrical signal, an optical signal, a thermal signal, etc. In some embodiments, the sensing device 100 can be a microphone (such as an air conduction microphone or a bone conduction microphone), a speaker (such as an air conduction speaker or a bone conduction speaker), an accelerometer, a pressure sensor, a hydrophone, an energy harvester, a gyroscope, etc. An air conduction microphone or an air conduction speaker refers to a microphone or speaker in which sound waves are conducted through air. A bone conduction microphone or a bone conduction speaker refers to a microphone or speaker in which sound waves are conducted in a solid (such as bone) in the form of mechanical vibrations.

[0073] For example, Figure 1 As shown, the sensing device 100 may include a housing 110 , a transducer unit 120 , and a processing circuit 130 (eg, an integrated circuit (IC)).

[0074] The housing 110 may be a regular or irregular three-dimensional structure having an internal accommodating cavity (i.e., a hollow portion). For example, it may be a hollow frame structure, including but not limited to regular shapes such as a rectangular frame, a circular frame, a regular polygonal frame, and any irregular shape. The housing 110 may be used to accommodate the energy displacing unit 120 and / or the processing circuit 130. In some embodiments, the housing 110 may be packaged in one or more ways such as plastic packaging and metal packaging. In some embodiments, the accommodating cavity of the housing 110 may be filled with one or more of a gas, a liquid, a solid, and the like. In some embodiments, the accommodating cavity may also include a vacuum structure.

[0075] The transducer unit 120 may be located in the housing cavity of the housing 110 or at least partially suspended in the housing cavity of the housing 110. The transducer unit 120 may be used to convert an external signal into a target signal. Taking a bone conduction microphone (also called a vibration sensing device) as an example, the external signal is a mechanical vibration signal and the target signal is an electrical signal. The transducer unit 120 may include a vibration pickup structure. The vibration pickup structure may have a certain elasticity. For example, the vibration pickup structure may be a vibration rod (such as a cantilever beam), a diaphragm, a vibration block, etc. The vibration pickup structure may generate deformation and / or displacement in response to the mechanical vibration signal. The transducer unit 120 may convert the deformation and / or displacement into a target signal (for example, an electrical signal). In some embodiments, the transducer unit 120 may include a piezoelectric transducer, an acoustic transducer, an electromagnetic transducer, a capacitive transducer, etc. In some embodiments, the transducer unit 120 may be electrically connected to the processing circuit 130 via a lead 140.

[0076] The processing circuit 130 can be used to process data and / or signals. In some embodiments, the processing circuit 130 can include one or more of a bipolar integrated circuit (e.g., a logic gate circuit, an emitter-coupled logic circuit, etc.), a unipolar integrated circuit (e.g., a field-effect transistor integrated circuit, an n-channel field-effect transistor integrated circuit, etc.), and the like.

[0077] In some embodiments, the processing circuit 130 may be located in the accommodating cavity of the shell 110 or at least partially suspended in the accommodating cavity of the shell 110. In some embodiments, the processing circuit 130 may also be located outside the accommodating cavity of the shell 110. For example, the processing circuit 130 may be disposed on the outer surface of the shell 110, and it may be connected to the transducer unit 120 for signal transmission via a lead. In some embodiments, the processing circuit 130 may process a target signal. Continuing with the example of a bone conduction microphone, the processing circuit 130 may convert the target signal into voice data, or send the target signal or voice data corresponding to the target signal to the cloud and / or other terminal devices. In some embodiments, the transducer unit 120 and the processing circuit 130 may be arranged in parallel (such as Figure 1 as shown), up and down arrangement or internal integration and other settings.

[0078] In some embodiments, the sensing device 100 may further include a lead 140. The lead 140 may be used to connect the transducer unit 120 and the processing circuit 130 signals. For example, the lead 140 may transmit a target signal or other signals (such as configuration instructions, acquisition instructions, etc.). In some embodiments, the lead 140 may not be necessary, and its function may be achieved through other connection methods. For example, the transducer unit 120 and the processing circuit 130 may be stacked up and down, and the transducer unit 120 and the processing circuit 130 may transmit data through a setting in which the ports of the two are in direct contact, thereby replacing the function of the lead 140.

[0079] Figure 2 is a schematic structural diagram of an exemplary microphone provided according to some embodiments of the present application.

[0080] like Figure 2 As shown, the microphone 200 may include a housing 210 , a transducer unit 220 , a processing circuit 230 , and a printed circuit board (PCB) 240 .

[0081] PCB 240 can be a phenolic PCB paper substrate, a composite PCB substrate, a glass fiber PCB substrate, a metal PCB substrate, a build-up multilayer PCB substrate, or the like. In some embodiments, PCB 240 can be an FR-4 grade glass fiber PCB substrate made of epoxy fiberglass cloth. Circuitry and other components of microphone 200 can be provided on PCB 240 (e.g., by laser etching, chemical etching, etc.). In some embodiments, PCB 240 can also be a flexible printed circuit board (FPC). In some embodiments, transducer unit 220 and processing circuit 230 are fixedly connected to PCB 240 via transducer unit fixing adhesive 250 and processing circuit fixing adhesive 260, respectively. In some embodiments, transducer unit fixing adhesive 250 and / or processing circuit fixing adhesive 260 can be conductive adhesive (e.g., conductive silver adhesive, copper powder conductive adhesive, nickel-carbon conductive adhesive, silver-copper conductive adhesive, etc.). The conductive adhesive can be conductive glue, conductive adhesive film, conductive rubber ring, conductive tape, etc. The transducer unit 220 and / or the processing circuit 230 are electrically connected to other components via circuits provided on the PCB 240. The transducer unit 220 and the processing circuit 230 may be directly connected via a wire 270 (eg, gold wire, copper wire, aluminum wire, etc.).

[0082] The housing 210 may be a regular or irregular three-dimensional structure having a cavity (i.e., a hollow portion) inside. For example, it may be a hollow frame structure, including but not limited to regular shapes such as a rectangular frame, a circular frame, a regular polygonal frame, and any irregular shape. The housing 210 is covered above the PCB 240 to seal the transducer unit 220, the processing circuit 230, the PCB 240, and the circuits and other components disposed thereon. The housing 210 may be made of metal (e.g., stainless steel, copper, etc.), plastic (e.g., polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), and acrylonitrile-butadiene-styrene copolymer (ABS), etc.), composite materials (e.g., metal-based composite materials or non-metal-based composite materials), etc. In some embodiments, the material used for the housing 210 is brass.

[0083] The transducer unit 220 can convert external vibration signals into electrical signals. Taking a bone conduction microphone as an example, the transducer unit 220 may include a base structure, a laminated structure (i.e., a vibration pickup structure), and at least one damping structure layer. In some embodiments, the base structure and the laminated structure may be located within the housing 210 of the bone conduction microphone, with the base structure fixedly connected to the inner wall of the housing 210, and the laminated structure supported by the base structure. In some embodiments, at least a portion of the laminated structure is physically connected to the base structure. "Physically connected" as used herein can be understood as connecting different parts of the same structure, or by fixing the individual components or structures together through welding, riveting, clamping, bolting, adhesive bonding, or other methods after separately manufacturing different components or structures, or by depositing a first component or structure onto a second component or structure during the manufacturing process through physical deposition (e.g., physical vapor deposition) or chemical deposition (e.g., chemical vapor deposition). In some embodiments, at least a portion of the laminated structure may be fixed to the upper or lower surface of the base structure, or at least a portion of the laminated structure may be fixed to the sidewall of the base structure. For example, the laminated structure may be a cantilever beam, which may be a plate-like structure, with one end of the cantilever beam connected to the upper surface, lower surface, or side wall of the base structure where the cavity of the base structure is located, and the other end of the cantilever beam is not connected to or in contact with the base structure, so that the other end of the cantilever beam is suspended in the cavity of the base structure. For another example, a bone conduction microphone may include a diaphragm layer (also called a suspended membrane structure), which is fixedly connected to the base structure, and the laminated structure is disposed on the upper surface or lower surface of the suspended membrane structure. For another example, the laminated structure may include a mass element and one or more support arms, the mass element being fixedly connected to the base structure via one or more support arms, one end of the support arm being connected to the base structure, and the other end of the support arm being connected to the mass element, so that part of the mass element and the support arm are suspended in the cavity of the base structure. It should be noted that the terms "located in the cavity" or "suspended in the cavity" in this application may mean suspended inside, below, or above the cavity.

[0084] In some embodiments, the laminate structure may include a vibration unit and a signal conversion unit (also referred to as an acoustic transducer unit). The vibration unit refers to the portion of the laminate structure that is easily deformed by an external force, and the vibration unit can be used to transfer the deformation caused by the external force to the signal conversion unit. The signal conversion unit refers to the portion of the laminate structure that converts the deformation of the vibration unit into an electrical signal. Specifically, the base structure can generate vibrations based on an external vibration signal, and the vibration unit deforms in response to the vibration of the base structure; the signal conversion unit generates an electrical signal based on the deformation of the vibration unit. It should be noted that the description of the vibration unit and the signal conversion unit here is only for the purpose of conveniently introducing the working principle of the laminate structure, and does not limit the actual composition and structure of the laminate structure. In some embodiments, the vibration unit may not be necessary, and its function can be completely implemented by the signal conversion unit. The signal conversion unit can directly generate an electrical signal in response to the vibration of the base structure. For example, the signal conversion unit can be a piezoelectric cantilever beam.

[0085] In some embodiments, the vibration unit and the signal conversion unit overlap to form a stacked structure. The signal conversion unit can be located on an upper layer of the vibration unit or on a lower layer of the vibration unit.

[0086] In some embodiments, the signal conversion unit may include at least two electrode layers (e.g., a first electrode layer and a second electrode layer) and a piezoelectric layer, wherein the piezoelectric layer may be located between the first electrode layer and the second electrode layer. A piezoelectric layer refers to a structure that can generate a voltage at its two end surfaces when subjected to an external force. In some embodiments, the piezoelectric layer can generate a voltage under the deformation stress of the vibration unit, and the first electrode layer and the second electrode layer can collect the voltage (electrical signal).

[0087] Taking a bone conduction microphone as an example, the vibration unit may include at least one elastic layer. The signal conversion unit may include a first electrode layer, a piezoelectric layer, and a second electrode layer arranged in sequence from top to bottom. The elastic layer is located on the surface of the first electrode layer or the second electrode layer. The elastic layer may deform during vibration. The piezoelectric layer generates an electrical signal based on the deformation of the elastic layer. The first electrode layer and the second electrode layer may collect the electrical signal. As an example only, the vibration unit may include a first elastic layer and a second elastic layer arranged in sequence from top to bottom. The first elastic layer and the second elastic layer may be a plate-like structure made of semiconductor material. In some embodiments, the semiconductor material may include silicon dioxide, silicon nitride, gallium nitride, zinc oxide, silicon carbide, etc. In some embodiments, the materials of the first elastic layer and the second elastic layer may be the same or different.

[0088] In some embodiments, the piezoelectric layer may be a piezoelectric polymer film obtained by a semiconductor deposition process (e.g., magnetron sputtering, MOCVD). In some embodiments, the material of the piezoelectric layer may include piezoelectric crystal materials and piezoelectric ceramic materials. Piezoelectric crystal refers to a piezoelectric single crystal. In some embodiments, the piezoelectric crystal material may include crystal, sphalerite, borate, tourmaline, zincite, GaAs, barium titanate and its derivative structure crystals, KH2PO4, NaKC4H4O6·4H2O (Roxi salt), etc., or any combination thereof. Piezoelectric ceramic material refers to a piezoelectric polycrystal formed by a random collection of fine grains obtained by solid-phase reaction and sintering between powders of different materials. In some embodiments, the piezoelectric ceramic material may include barium titanate (BT), lead zirconate titanate (PZT), lead barium lithium niobate (PBLN), modified lead titanate (PT), aluminum nitride (AIN), zinc oxide (ZnO), etc., or any combination thereof. In some embodiments, the piezoelectric layer material may also be a piezoelectric polymer material, such as polyvinylidene fluoride (PVDF). In some embodiments, the first electrode layer and the second electrode layer are made of a conductive material. Exemplary conductive materials may include metals, alloy materials, metal oxide materials, graphene, etc., or any combination thereof. In some embodiments, the metal and alloy materials may include nickel, iron, lead, platinum, titanium, copper, molybdenum, zinc, or any combination thereof. In some embodiments, the alloy material may include copper-zinc alloy, copper-tin alloy, copper-nickel-silicon alloy, copper-chromium alloy, copper-silver alloy, etc., or any combination thereof. In some embodiments, the metal oxide material may include RuO2, MnO2, PbO2, NiO, etc., or any combination thereof.

[0089] The damping structure layer may refer to a structure having damping properties. In some embodiments, the damping structure layer may be a membrane-like structure or a plate-like structure. Furthermore, at least one side of the damping structure layer may be connected to the base structure. In some embodiments, the damping structure layer may be located on the upper surface and / or lower surface of the laminate structure or between multiple layers of the laminate structure. For example, when the laminate structure is a cantilever beam, the damping structure layer may be located on the upper surface and / or lower surface of the cantilever beam. For another example, when the laminate structure is a support arm and a mass element, when the mass element protrudes downward relative to the support arm, the damping structure layer may be located on the lower surface of the mass element and / or the upper surface of the support arm. In some embodiments, for macro-sized laminate structures and base structures, the damping structure layer may be directly bonded to the base structure or laminate structure. In some embodiments, for micro-electromechanical systems (MEMS) devices, the damping structure layer may be connected to the laminate structure and base structure using semiconductor processes, such as evaporation, spin coating, microassembly, etc. In some embodiments, the shape of the damping structure layer can be regular or irregular, such as circular, elliptical, triangular, quadrilateral, hexagonal, octagonal, etc. In some embodiments, the output effect of the electrical signal of the bone conduction microphone can be improved by selecting the material, size, thickness, etc. of the damping structure layer.

[0090] When the housing 210 of the bone conduction microphone is vibrated by an external force (for example, the vibration of a person's face when speaking drives the housing 210 to vibrate), the vibration of the housing 210 drives the base structure to vibrate. Due to the different properties of the laminated structure and the housing structure (or base structure), the laminated structure and the housing 210 cannot maintain completely consistent movement, resulting in relative motion, which in turn causes the vibration unit of the laminated structure to deform. Furthermore, when the vibration unit deforms, the piezoelectric layer of the signal conversion unit is subjected to the deformation stress of the vibration unit, generating an electric potential difference (voltage). At least two electrode layers (for example, a first electrode layer and a second electrode layer) located on the upper and lower surfaces of the piezoelectric layer in the signal conversion unit can collect this potential difference and convert the external vibration signal into an electrical signal.

[0091] The damping of the damping structure layer varies under different stress (deformation) states. For example, it exhibits greater damping under high stress or large amplitude. Therefore, the characteristics of the laminated structure in which the amplitude is small in the non-resonance region and large in the resonance region can be utilized. By adding a damping structure layer, the sensitivity of the bone conduction microphone in the non-resonance region can be reduced less while reducing the quality factor Q value in the resonance region, so that the frequency response of the bone conduction microphone is relatively flat throughout the entire frequency range. The bone conduction microphone can be applied to headphones (for example, bone conduction headphones or air conduction headphones), glasses, virtual reality equipment, helmets, etc. The bone conduction microphone can be placed on the human head (for example, face), neck, near the ears, and on the top of the head. The bone conduction microphone can pick up the vibration signal of the bones when a person speaks and convert it into an electrical signal to achieve sound collection. It should be noted that the base structure is not limited to a structure independent of the housing 210 of the bone conduction microphone. In some embodiments, the base structure can also be part of the housing 210 of the bone conduction microphone.

[0092] The processing circuit 230 may acquire the electrical signal from the sensor element 230 and perform signal processing. In some embodiments, the signal processing may include frequency modulation processing, amplitude modulation processing, filtering processing, noise reduction processing, etc.

[0093] Figure 3 is a schematic diagram of an exemplary equivalent vibration model of a transducer unit provided according to some embodiments of the present application.

[0094] The transducer unit 120 can be simplified and equivalent to Figure 3 The mass-spring-damper system shown in Figure 1 is subjected to forced vibration by an excitation force F. The motion of this system can be described by the following differential equation:

[0095]

[0096] Where M is the system mass, R is the system damping, K is the system elastic coefficient, F is the driving force amplitude, x is the system displacement, and ω is the external force circular frequency. Solving the above equation for the steady-state displacement yields:

[0097] x=x a cos(ωt-θ), (2)

[0098] in,

[0099] When the sensor device 100 is actually working, x corresponds to the deformation of the vibration-electrical signal conversion module of the transducer unit 120, and the magnitude of x ultimately corresponds to the magnitude of the electrical signal output. The displacement amplitude ratio (normalized) is:

[0100]

[0101]

[0102] in, is the mechanical quality factor; is the static displacement amplitude (or the displacement amplitude when ω=0); ω0 is the system resonant frequency.

[0103] Figure 4 FIG is a schematic diagram of a displacement resonance curve of an exemplary sensing device according to some embodiments of the present application. The sensing device 100 is composed of transducer units with different parameters (elastic coefficient, mass, damping), and its normalized displacement resonance curve is as follows: Figure 4 The horizontal axis corresponds to the ratio of the frequency of the external force (or vibration) to the resonant frequency of the system. The vertical axis corresponds to the A value of formula (3). It can be seen that for different sensor devices 100, the transducer units 120 are different and have different mechanical quality factors Q m The value corresponds to different curves in the figure, and the displacement amplitude ratio A is different. The ratio of the frequency of the external force (or vibration) to the resonant frequency of the system When Q is 1, the system resonates and the displacement change is the largest. m The larger the transducer unit, the larger the A value and the steeper the curve; m The smaller the value of the transducer unit, the smaller the A value and the flatter the curve. Therefore, the quality factor Q of the transducer unit 120 can be adjusted. m value (such as changing its structure) and adjusting the Q value.

[0104] The principle of microphone voltage signal generation is that the vibration-electrical signal conversion module (i.e., transducer unit) and the microphone housing generate relative displacement (for example, the electret microphone generates a voltage signal by deforming the diaphragm and changing the distance between the diaphragm and the substrate; the cantilever beam bone conduction microphone generates an electrical signal by deforming the cantilever vibration device to generate a piezoelectric effect). The greater the displacement, the greater the output signal. Obviously, the vibration-electrical signal conversion module of the microphone fully complies with the following. Figure 4 The displacement resonance curve.

[0105] When reduced When the resonant frequency is adjusted, the system's resonant frequency decreases. When the resonant frequency is changed, the sensitivity of signals before the resonant frequency increases, but the sensitivity of signals at frequencies after the resonant frequency decreases. When adjusting the resonant frequency of the sensor device 100 to adjust sensitivity, the frequency range must be considered. In some embodiments, the resonant frequency of the sensor device 100 is between 1500 Hz and 6000 Hz.

[0106] Figure 5 is a mechanical equivalent schematic diagram of an exemplary sensing device provided according to some embodiments of the present application.

[0107] In some embodiments, sensing device 500 may include a transducer unit 520 and an additional resonant system 530 (also referred to as a first resonant system 530). In some embodiments, sensing device 500 can be considered to incorporate the first resonant system 530 in addition to the transducer unit 520. For example, in this embodiment, first resonant system 530 may be a spring (Km4)-mass (Mm4)-damper (Rm4) system. First resonant system 530 may be coupled between a housing (not shown) and transducer unit 520. Due to the action of first resonant system 530, when the housing receives an external vibration signal, the external vibration signal is transmitted to transducer unit 520 via the housing region connected to transducer unit 520 and the housing region connected to first resonant system 530, respectively. Consequently, the mechanical response of sensing device 500 is altered compared to sensing device 100. Accordingly, the electrical, acoustic, and / or thermal responses of sensing device 500 are altered compared to sensing device 100.

[0108] In some embodiments, the first resonant system 530 may be formed by filling a cavity of the housing with liquid. For example, the liquid fills the cavity in the housing, and the transducer unit 520 is wrapped in the liquid.

[0109] Figure 6 Schematic diagram of a sensing device filled with liquid according to some embodiments of the present application. Figure 6 As shown, liquid 610 can be selected from liquids that have safety properties (e.g., non-flammable and non-explosive) and stability properties (e.g., non-volatile and non-deteriorating at high temperatures). For example, liquid 610 can include oil (e.g., silicone oil, glycerin, castor oil, engine oil, lubricating oil, hydraulic oil (e.g., aviation hydraulic oil)), water (e.g., pure water, other inorganic or organic aqueous solutions (e.g., salt water)), oil-water emulsions, or other liquids that meet the performance requirements, or a combination of one or more thereof.

[0110] The density and kinematic viscosity of the liquid 610 are within a certain density range and kinematic viscosity range, respectively. In some embodiments, the density range and kinematic viscosity range can be set by the user or determined based on the performance of the sensor device 500 (e.g., sensitivity, background noise level, resonance peak value, resonance peak (also referred to as resonance peak) frequency range, peak-to-valley value and / or quality factor Q, etc.). In some embodiments, silicone oil can be used as the liquid 610. Silicone oil has the characteristics of high temperature resistance, low volatility, and a wide viscosity range. Its density is about 0.94 kg / m 3 , a wide range of optional kinematic viscosities (e.g., 0.1-1000 stokes (cst)).

[0111] The liquid 610 can be injected into the housing cavity of the housing 510 in a specific manner. For a detailed description of injecting the liquid 610 into the housing cavity of the housing 510, please refer to other parts of this specification, such as Figure 11 and its description.

[0112] In some embodiments, the frequency response curve of the sensing device 500 includes at least two resonance peaks. The at least two resonance peaks include a first resonance peak and a second resonance peak. The resonant frequency corresponding to the first resonance peak is mainly related to the properties of the transducer unit 520 (for example, shape, material, structure, etc.). The second resonance peak is the resonance peak generated by the action of the first resonance system 530, and its corresponding resonant frequency is mainly related to one or more mechanical parameters of the first resonance system 530 (for example, the spring (Km4), mass (Mm4), damping (Rm4) equivalent to the resonance system, etc.). In order to enable the sensing device 500 to be applicable to different scenarios, the resonant frequency corresponding to the first resonance peak (also called the first resonant frequency) and the resonant frequency corresponding to the second resonance peak (also called the second resonant frequency) can satisfy different relationships. For example, the second resonant frequency can be less than, equal to, or greater than the first resonant frequency.

[0113] For illustrative purposes only, due to the presence of the second resonance peak corresponding to the first resonance system 530, the frequency response curve of the sensor device 500, especially in the low and medium frequency bands where voice information is relatively rich, will be improved, so that its sensitivity will be improved. In addition, since the first resonance system 530 acts on the transducer unit 520, the vibration characteristics of the sensor device 500 will be changed compared to when there is no first resonance system 530. Specifically, the first resonance system 530 acts on the transducer unit 520, which can affect the mass, stiffness and / or damping of the sensor device 500, and the effect is equivalent to causing the Q value of the first resonance peak of the sensor device 500 to change relative to the Q value of the sensor device not connected to the first resonance system 530 (for example, the Q value is reduced). For more detailed descriptions of the frequency response curve of the sensor device 500 and the first resonance peak and the second resonance peak, please refer to other places in this application specification, such as Figure 9 and Figure 10 and its description.

[0114] In some embodiments, the first resonant system 530 can reduce external impacts received by the transducer unit 520 to protect the transducer unit 520. For example, if the first resonant system 530 is a liquid 610 that fills the chamber of the sensor device 500, the viscosity of the liquid 610 and its inherent stiffness, which is much lower than that of the device material, can improve the reliability of the sensor device 500 when receiving external impact loads (for example, a bone conduction microphone is required to withstand an acceleration of 10,000 g without damage). Specifically, the viscosity of the liquid 610 can absorb and dissipate some of the impact energy, thereby significantly reducing the impact load received by the transducer unit 520.

[0115] Furthermore, due to stress during processing, sensor device 100, particularly cantilever beam devices, often experiences deformation, such as bending (along length and width) and twisting. However, cantilever beam structures are commonly used in sensing devices such as bone conduction microphones and accelerometers. Since the housing of sensor device 500 is filled with liquid 610, the gravity, surface tension, and viscosity of liquid 610 can be utilized to correct device deformation, resulting in less deformation, more stable output, and closer to the actual design.

[0116] Figure 7 is a mechanical equivalent schematic diagram of an exemplary sensing device provided according to some embodiments of the present application. Figure 7 As shown, the sensing device 700 may include a transducer unit 720 and a second resonant system 740. In some embodiments, the sensing device 700 may be considered to adjust the first resonant system 530 based on the transducer unit 720 to form the second resonant system 740. For example, in this embodiment, the second resonant system 740 is newly added with a spring (Km3) and a damper (Rm3) compared to the first resonant system 530. The second resonant system 740 may be disposed between the housing 710 and the transducer unit 720. For example, Figure 7As shown, the spring (Km3)-damper (Rm3) of the second resonant system 740 can be connected in series with the spring (Km4)-mass (Mm4)-damper (Rm4) of the first resonant system 530, and indirectly act on the transducer unit 720. For another example, the spring (Km3)-damper (Rm3) of the second resonant system 740 can be connected in series with the spring (Km4)-mass (Mm4)-damper (Rm4) of the first resonant system 530, and directly act on the transducer unit 720. Due to the action of the second resonant system 740, when the housing 710 receives an external vibration signal, the external vibration signal will be transmitted to the transducer unit 720 through the housing area connected to the transducer unit 720 and the housing area connected to the second resonant system 740, respectively, through the second resonant system 740. Therefore, the mechanical response of the sensor device 700 is different from that of the sensor device 500. Accordingly, the electrical, acoustic, and / or thermal responses of sensing device 700 are changed compared to sensing device 500. Furthermore, due to the newly introduced spring (Km3) and damping (Rm3) of second resonant system 740, the vibration characteristics (e.g., stiffness-damping, etc.) of sensing device 700 are changed compared to sensing device 500.

[0117] In some embodiments, the second resonant system 740 can be formed by filling the accommodating cavity of the sensor device 700 with different media. For example, the accommodating cavity of the sensor device 700 can be partially filled with liquid to form a second resonant system 740 in which liquid and air cavities (in this specification, air cavities may also be referred to as bubbles) coexist within the accommodating cavity. In this case, the liquid within the accommodating cavity can be equivalent to the aforementioned spring (Km4)-mass (Mm4)-damping (Rm4), and the bubbles can be equivalent to the aforementioned spring (Km3) and damping (Rm3). For another example, the accommodating cavity of the sensor device 700 can be filled with liquids of different densities that are immiscible with each other to form the second resonant system 740. In some embodiments, the medium filled into the accommodating cavity of the sensor device 700 can be set by the user or determined based on the performance of the sensor device 700 (e.g., sensitivity, noise floor level, resonance peak value, resonance peak frequency range, peak-to-valley value, and / or quality factor Q, etc.).

[0118] Figure 8 Schematic diagram of a sensing device filled with liquid and bubbles according to some embodiments of the present application. Figure 8As shown, in the sensing device 700, the accommodating cavity of the shell 710 is filled with liquid 810 and air bubbles 820. The liquid 810 in the sensing device 700 can be the same type of liquid as or different type of liquid as that of the sensing device 500. For example, the sensing device 700 and the sensing device 500 are both filled with silicone oil of the same kinematic viscosity. For another example, the sensing device 700 and the sensing device 500 are respectively filled with different types of liquids 810 or the same liquid 810 of different kinematic viscosities (for example, silicone oils with kinematic viscosities of 0.65 cst and 200 cst, respectively). The liquid 810 and the air bubbles 820 can be injected or formed in the accommodating cavity of the shell 710 in a specific manner. Regarding the method of injecting or forming the liquid 810 and the air bubbles 820 in the accommodating cavity of the shell 710, please refer to the description elsewhere in this application specification, such as Figure 11 and its description.

[0119] In some embodiments, the frequency response curve of the sensor device 700 includes at least two resonance peaks. The at least two resonance peaks include a third resonance peak and a fourth resonance peak. The third resonance peak is the resonance peak corresponding to the transducer unit 720, and the fourth resonance peak is the resonance peak generated by the second resonant system 740.

[0120] In some embodiments, the third resonant frequency (the resonant frequency corresponding to the third resonance peak) and the fourth resonant frequency (the resonant frequency corresponding to the fourth resonance peak) of the sensing device 700 may satisfy different relationships. For example, when the second resonant system 740 is formed by the liquid 810 and the bubbles 820, due to the large compressibility of the bubbles 820 (compared to the case of pure liquid 810) and the low stiffness, the sensing device 700 may have a resonant frequency in the low frequency or medium-low frequency band. For example, the fourth resonant frequency is a low frequency or medium-low frequency, and the third resonant frequency may be greater than the fourth resonant frequency, for example, the third resonant frequency is in a higher frequency band. For another example, the third resonant frequency and the fourth resonant frequency are both medium-low frequencies. In this application, low frequency, medium-low frequency, and medium-high frequency refer to frequencies whose frequency values are within a certain range. For example, the frequency range corresponding to low frequency, medium-low frequency, or medium-high frequency is within 7000 Hz, within 5000 Hz, within 3000 Hz, within 1000 Hz, within 500 Hz, etc. For example, the frequency range corresponding to the higher frequency band is above 2000Hz, above 5000Hz, above 8000Hz, etc. The third resonant frequency is a higher frequency than the fourth resonant frequency. Optionally, the difference between the two resonant frequencies is 100-6000Hz. When the sensing device 700 has a resonant frequency in the low frequency or mid-low frequency range, its sensitivity at low frequency will be higher than that of the sensing device that is not provided with the second resonant system 740; when the sensing device 700 further has a resonant frequency in the high frequency or mid-high frequency range, its frequency response curve is also flatter in the range between the two resonant peaks, which is more conducive to the acquisition of effective voice signals in this frequency band.

[0121] In addition, since the second resonance system 740 acts on the transducer unit 720, the vibration characteristics of the sensor device 700 will be changed compared to the sensor device without the second resonance system 740. For example, the second resonance system 740 acts on the transducer unit 720, which can affect the stiffness and / or damping of the sensor device 700, and the effect is equivalent to causing the Q value of the third resonance peak of the sensor device 700 to change (for example, the Q value is reduced) compared to the sensor device without the second resonance system 740. For more detailed descriptions of the frequency response curve of the sensor device 700 and the third resonance peak and the fourth resonance peak, please refer to other places in this application specification, such as Figure 9 and Figure 10 and its description.

[0122] In some embodiments, the second resonant system 740 can reduce external impacts on the transducer unit 720 to protect it. For example, if liquid 810 and air bubbles 820 are introduced into the housing 710, the sensor device 700 can be more resilient to external impact loads. Due to the viscosity of the liquid 810 and the high compressibility of the gas, they can absorb and dissipate some of the impact energy, significantly reducing the impact load on the transducer unit 720.

[0123] Furthermore, sensor device 700 often experiences deformation due to stress during processing. By injecting liquid 810 and bubbles 820 into the chamber, the gravity, surface tension, and viscosity of liquid 810 can be utilized to correct device deformation, minimizing deformation of sensor device 700 and achieving more stable output, closer to the actual design.

[0124] It should be noted that the above description of the sensor device 700 is merely illustrative and does not limit this specification to the embodiments described. It is understood that those skilled in the art, after understanding the principles of the system, may arbitrarily combine its structures and modules, or form subsystems connected to other modules without departing from these principles.

[0125] Figure 9 is an exemplary frequency response curve of the sensing device 500 or 700 provided according to some embodiments of the present application.

[0126] For example, Figure 9 As shown, dashed line 910 represents the frequency response curve of a sensor device without an equivalent resonant system, and solid line 920 represents the frequency response curve of sensor device 500 or 700. The horizontal axis represents frequency in Hertz (Hz), and the vertical axis represents sensitivity in decibels (dBV). Frequency response curve 910 includes a resonance peak 911. Frequency response curve 920 includes a first (or third) resonance peak 921 and a second (or fourth) resonance peak 922. For sensor device 500, the frequency corresponding to first resonance peak 921 is the first resonant frequency, and the frequency corresponding to second resonance peak 922 is generated by the first resonant system 530. For sensor device 700, the frequency corresponding to third resonance peak 921 is the third resonant frequency, and the frequency corresponding to fourth resonance peak 922 is generated by the second resonant system 740. The frequency corresponding to fourth resonance peak 922 is the fourth resonant frequency.

[0127] It should be noted that the second (or fourth) resonance peak 922 shown in the figure is to the left of the first (or third) resonance peak 921, that is, the frequency corresponding to the second (or fourth) resonance peak 922 is lower than the frequency corresponding to the first (or third) resonance peak. In some embodiments, by changing the mechanical parameters of the transducer unit or the first (or second) resonant system, the frequency corresponding to the second (or fourth) resonance peak 922 can be made higher than the frequency corresponding to the first (or third) resonance peak 921, that is, the second (or fourth) resonance peak 922 is to the right of the first (or third) resonance peak 921. For example, for a sensing device 500 filled with liquid, its second (or fourth) resonance peak 922 may be to the left or right of the first (or third) resonance peak 921, and its position may be related to the properties of the filled liquid (e.g., density, kinematic viscosity, volume, etc.). For example, if the density of the liquid decreases or the kinematic viscosity increases, its resonance peak will shift toward higher frequencies.

[0128] In some embodiments, the frequency corresponding to the resonance peak 911 is in the range of 100 Hz to 10,000 Hz. In some embodiments, the frequency corresponding to the resonance peak 911 is in the range of 1,500 Hz to 5,000 Hz.

[0129] In some embodiments, the resonant frequency (first resonant frequency or third resonant frequency) corresponding to the first (or third) resonant peak 921 is different from the resonant frequency corresponding to the resonant peak 911. For example, for a sensing device 500 in which the housing 110 cavity is filled with liquid, the liquid serves as the first resonant system 530. Since the liquid is not easily compressed, the rigidity of the system itself increases. Therefore, the first frequency corresponding to the first resonant peak 921 is greater than the resonant frequency corresponding to the resonant peak 911, that is, the first resonant peak 921 is shifted to the right relative to the resonant peak 911.

[0130] In some embodiments, the frequency corresponding to the second (or fourth) resonance peak 922 is in the range of 100 Hz to 5000 Hz. In some embodiments, the frequency corresponding to the second (or fourth) resonance peak 922 is in the range of 1000 Hz to 2000 Hz.

[0131] In some embodiments, the fourth resonant frequency is lower than the second resonant frequency. For a sensing device 500 in which the housing 510 cavity is filled with liquid, the liquid serves as the first resonant system 530. In contrast, in a sensing device 700 in which the housing 710 cavity contains both liquid and bubbles, the liquid and bubbles each serve as the second resonant system 740. The overall stiffness of the combined system is lower than that of the liquid, and therefore the fourth resonant frequency is lower than the second resonant frequency.

[0132] In some embodiments, the output quality of the sensing device 500 or 700 can be improved by adjusting the structure and material of the transducer unit, as well as one or more mechanical parameters (e.g., the type of filling liquid, bubble size, etc.) in the first (or second) resonant system, to make the gap between the two resonance peaks 921 and 922 on the frequency response curve 920 relatively flat. In some embodiments, the sensitivity difference between the valley between the resonance peaks 921 and 922 and the peak value of the higher of the resonance peaks 921 and 922 is no greater than 30 dBV, and the ratio of the sensitivity difference to the peak value of the higher peak is no greater than 0.2. In some embodiments, the sensitivity difference between the valley between the resonance peaks 921 and 922 and the peak value of the higher of the resonance peaks 921 and 922 is no greater than 10 dBV, and the ratio of the sensitivity difference to the peak value of the higher peak is no greater than 0.1. In some embodiments, to make the frequency response curve 920 flat, the sensitivity difference between the valley between the resonance peaks 921 and 922 and the peak of the higher peak between the resonance peaks 921 and 922 is no more than 5 dBV, and the ratio of the sensitivity difference to the peak of the higher peak is no more than 0.05.

[0133] Accordingly, when the difference in the resonant frequencies corresponding to resonance peaks 921 and 922 (the frequency of resonance peak 921 is represented by f0 (which is close to resonance peak 911), the frequency of resonance peak 922 is represented by f1, and the difference in the resonant frequencies corresponding to resonance peaks 921 and 922 is represented by frequency difference Δf1) is within a certain range, the frequency response curve between resonance peaks 921 and 922 can be relatively flat. In some embodiments, the frequency difference Δf1 is within the range of 200-2000 Hz, and the ratio of the frequency difference Δf1 to f0 is within the range of 0.2-0.65. In some embodiments, the frequency difference Δf1 is within the range of 800-1500 Hz, and the ratio of the frequency difference Δf1 to f0 is within the range of 0.3-0.6.

[0134] like Figure 9 As shown, compared to frequency response curve 910, frequency response curve 920 exhibits a higher and more stable sensitivity improvement (i.e., a difference, represented by ΔV1) within the frequency range within the resonant frequency f1 corresponding to the second (or fourth) resonance peak 922. In some embodiments, ΔV1 is in the range of 10 dBV to 60 dBV.

[0135] The presence of the first resonant system 530 or the second resonant system 740 suppresses the resonant peak corresponding to the transducer unit of the sensor device 500 or 700, resulting in a relatively low Q value at the first (or third) resonant peak 921 of the frequency response curve 920. This flattens the frequency response curve within the desired frequency band (e.g., mid- and low-frequency bands), and the difference between the highest peak and the lowest valley of the overall frequency response curve 920 (also known as the peak-to-valley value, represented by ΔV2) is within a certain range. In some embodiments, the peak-to-valley value does not exceed 30 dBV, and the ratio of the peak-to-valley value to the peak value of the highest peak does not exceed 0.2. In some embodiments, the peak-to-valley value does not exceed 5 dBV, and the ratio of the peak-to-valley value to the peak value of the highest peak does not exceed 0.05.

[0136] For the sensing device 700, in some embodiments, the frequency corresponding to the fourth resonance peak 922 (i.e., the fourth resonance frequency) is a mid-low frequency, and the frequency corresponding to the third resonance peak 921 (i.e., the third resonance frequency) is a mid-high frequency. In some embodiments, the difference between the minimum sensitivity of the frequency response curve 920 within the frequency range up to the resonance frequency f1 and the peak value of the fourth resonance peak is no greater than 30 dBV, and the ratio thereof is no greater than 0.2. In some embodiments, the difference between the minimum sensitivity of the frequency response curve 920 within the frequency range up to the resonance frequency f1 and the peak value of the fourth resonance peak is no greater than 20 dBV, and the ratio thereof is no less than 0.15. In some embodiments, the difference between the minimum sensitivity of the frequency response curve 920 within the frequency range up to the resonance frequency f1 and the peak value of the fourth resonance peak is no greater than 10 dBV, and the ratio thereof is no greater than 0.1.

[0137] In some embodiments, the frequency response of the sensing device 500 or 700 can be described by one or more of the parameters associated with the curve 920, such as the peak value and frequency of the first (or third) resonance peak 921, the peak value and frequency of the second (or fourth) resonance peak 922, the Q value, Δf1, ΔV1, ΔV2, the ratio of Δf1 to f0, the ratio of the peak-to-valley value to the peak value of the highest peak, the first-order coefficient, the second-order coefficient, the third-order coefficient of the equation determined by fitting the frequency response curve, etc. In some embodiments, the frequency response of the sensing device 500 or 700 can be related to the properties of the liquid filled therein and / or the parameters of the transducer unit. The liquid properties can include, for example, the liquid density, the liquid kinematic viscosity, the liquid volume, the presence of bubbles, the bubble volume, the bubble location, the number of bubbles, etc. The parameters of the transducer unit can include, for example, the mass, size, stiffness, etc. of the transducer unit (e.g., a cantilever beam). In some embodiments, the frequency response of the sensing device 500 or 700 can also be related to parameters such as the internal structure (e.g., the shape of the accommodating cavity), size, and stiffness of the housing.

[0138] In some embodiments, to obtain an ideal output frequency response (e.g., frequency response curve 920) for sensing device 500 or 700, the ranges of the aforementioned parameters affecting the frequency response (also known as frequency response influencing factors, including, for example, the properties of the filling liquid and / or the parameters of the transducer element) can be determined through computer simulation, phantom experiments, and other methods. In some embodiments, the influence of each factor on the frequency response of sensing device 500 or 700 can be individually determined by controlling variables based on simulation. For example, the performance of sensing devices with different chamber structures can be tested under the same liquid and filled conditions. For another example, the performance of devices with different housing stiffness characteristics can be tested under the same liquid and filled conditions. For another example, the performance of sensing devices with the same housing size can be tested under different conditions of being filled with liquid and filled with liquid and bubbles. For another example, the performance of sensing devices with different bubble sizes can be tested under the condition that the bubbles do not cover the transducer element (e.g., piezoelectric transducer). For another example, the performance of sensing devices with different bubble sizes can be tested under the condition that the bubbles cover the transducer element (e.g., piezoelectric transducer).

[0139] In some embodiments, some factors are correlated with the effects of other factors on the frequency response of the sensing device 500 or 700. Therefore, the effects of these parameter pairs or groups on the frequency response of the sensing device 500 or 700 can be determined using corresponding parameter pairs or groups. For example, as the housing height increases, the volume of the accommodating cavity increases, the housing mass increases, and the volume of the liquid filled therein also increases accordingly. Therefore, the housing height, housing mass, and liquid volume (or the ratio of any two of these parameters, or the product of at least two of these parameters) can be used as a parameter group to test their effect on the performance of the sensing device. For another example, liquid viscosity and density can be used as a parameter pair to test the effect of this parameter pair (or their ratio, product, etc.) on the frequency response of the sensing device 500 or 700.

[0140] In some embodiments, the effect of parameter pairs or parameter groups corresponding to each factor or multiple factors on the frequency response of the sensor device 500 or 700 can be determined by means of a phantom test.

[0141] For example, for a sensor device 500 filled with liquids of varying viscosities, the greater the liquid viscosity, the greater the system damping and the smaller the Q value of the frequency response of the sensor device 500. For a sensor device 700 filled with liquid and bubbles, within a certain kinematic viscosity range, the greater the kinematic viscosity of the filled liquid, the greater the improvement in sensitivity of the sensor device 700.

[0142] In some embodiments, the kinematic viscosity of the liquid may be 0.1-5000 cSt. In some embodiments, the kinematic viscosity of the liquid may be 0.5-500 cSt. In some embodiments, the kinematic viscosity of the liquid may be 50-200 cSt.

[0143] For example, for the liquid-filled sensing device 500 , taking a bone conduction microphone or a single-axis accelerometer as an example, within a certain range, the length of the cantilever beam becomes shorter and the overall effective frequency band is expanded.

[0144] In some embodiments, the cantilever beam thickness, width, and length may be 0.5 μm-3 mm, 50 μm-500 mm, and 200 μm-1 cm, respectively. In some embodiments, the cantilever beam thickness, width, and length may be 2 μm-20 μm, 200 μm-2 mm, and 800 μm-4 mm, respectively.

[0145] For example, for the sensor device 500 filled with liquid, by increasing the size of the accommodating cavity, the sensitivity of the sensor device at the intermediate frequency can be improved, and the frequency response suppression effect of the liquid on the sensor device at the intermediate frequency can be reduced, making the frequency response curve flatter.

[0146] For example, for a sensor device 500 filled with liquid and having different accommodating cavity heights, within a certain range, the higher the accommodating cavity height, the higher the mid- and low-frequency output sensitivity of the sensor device 500 .

[0147] In some embodiments, the length, width, and height of the accommodating cavity of the sensing device are 1-30 mm, 1-30 mm, and 0.5-30 mm, respectively. Optionally, the accommodating cavity of the sensing device has a larger size. In some embodiments, the length, width, and height of the accommodating cavity of the sensing device are 10-200 mm, 10-100 mm, and 10-100 mm, respectively. In some embodiments, the length, width, and height of the accommodating cavity of the sensing device are 10-50 mm, 10-30 mm, and 10-30 mm, respectively.

[0148] For example, compared to the fully liquid-filled sensor device 500, the sensor device 700 filled with liquid and bubbles may have a higher overall output gain due to the fact that gas is easily compressible and has low rigidity, while liquid is not easily compressible. This may result in excessive stiffness and overdamping. For example, in some embodiments, the second resonance peak of the sensor device 500 may disappear due to overdamping, thereby affecting the sensitivity of the sensor device 500 at mid- and low-frequency levels.

[0149] For example, in the sensing device 700 filled with liquid and bubbles, when the bubbles do not cover the transducer unit (eg, piezoelectric transducer), the sensitivity of the sensing device 700 increases as the volume of the bubbles increases.

[0150] In some embodiments, the ratio of the volume of the bubbles to the volume of the liquid can be 5%-90%. In some embodiments, the ratio of the volume of the bubbles to the volume of the liquid can be 20%-60%. In some embodiments, the ratio of the volume of the bubbles to the volume of the liquid can be 30%-50%.

[0151] In some embodiments, the bubbles may be located at different positions within the sensing device 700. For example, the bubbles may be located inside the liquid. For another example, the bubbles may be located between the liquid and the shell. In some embodiments, the transducer unit 720 may separate the accommodating cavity into a front cavity and a rear cavity located on opposite sides of the vibration pickup structure. In this specification, the rear cavity refers to a closed or semi-closed space formed by the base of the transducer unit and the vibration pickup structure (such as a cantilever beam). For example, taking a bone conduction microphone as an example, the accommodating cavity can be divided into a front cavity and a rear cavity with the plane where the cantilever beam is located as the dividing plane. For the sensing device 700 filled with liquid and bubbles, when the bubbles are located in the front cavity of the sensing device and are not in contact with the transducer unit (for example, the vibration pickup structure), the sensitivity gradually increases with the increase of bubbles.

[0152] In some embodiments, when bubbles of a certain size are provided in both the front and rear cavities of the liquid- and bubble-filled sensor device 700, a large gain in the low-frequency portion can be achieved, and the intermediate frequency effectively suppresses the Q value of the resonance peak of the sensor device 700, but does not suppress the sensitivity of other regions outside the resonance peak region of the corresponding sensor device 700, thereby making the frequency response of the sensor device 700 relatively flat in the range from low frequency to intermediate frequency.

[0153] In some embodiments, the ratio of the volume of the bubbles in the front cavity and the back cavity to the volume of the liquid can be 5%-95%. In some embodiments, the ratio of the volume of the bubbles in the front cavity and the back cavity to the volume of the liquid can be 30%-50%.

[0154] It should be noted that the above description of the frequency response curves of sensor devices 500 or 700 is merely illustrative and does not limit this specification to the illustrated embodiments. It is understood that those skilled in the art, after understanding the principles of the system, may arbitrarily adjust its structure and composition without departing from these principles. Such variations are within the scope of protection of this application.

[0155] Figure 10 is an exemplary frequency response curve of the sensing device 500 or 700 provided according to some embodiments of the present application.

[0156] like Figure 10As shown, the dotted line 1010 represents the frequency response curve of the sensor device without an equivalent resonance system, and the solid line 1020 represents the frequency response curve of the sensor device 500 or 700. The frequency response curve 1010 includes a resonance peak 1011. In some embodiments, the higher resonance frequency corresponding to the sensor device without an equivalent resonance system is not in the required frequency range (for example, 100-5000 Hz, 500-7000 Hz, etc.). In some embodiments, the resonance frequency corresponding to the sensor device without an equivalent resonance system may be in a higher frequency range. For example, in some embodiments, the resonance frequency corresponding to the sensor device without an equivalent resonance system is higher than 7000 Hz. Accordingly, the sensor device without an equivalent resonance system may have a higher stiffness at this time, and also provide the sensor device with higher impact strength and reliability.

[0157] The frequency response curve 1020 includes a first (or third) resonance peak (not shown) and a second (or fourth) resonance peak 1021. In some embodiments, the frequency corresponding to the first (or third) resonance peak is close to or the same as the corresponding resonant frequency in the frequency response curve 1010. In some embodiments, the frequency response curve 1020 is similar to the frequency response curve 1010. Figure 9 Compared with the frequency response curve 920 in FIG, except that the first (or third) resonance peak is shifted to the right, the two are roughly the same. The frequency corresponding to the second (or fourth) resonance peak 1021 is Figure 9 The frequency range corresponding to the second (or fourth) resonance peak 922 is the same or similar.

[0158] In some embodiments, within a desired frequency range (e.g., within 2000 Hz, within 3000 Hz, within 5000 Hz, etc.), the difference between the maximum and minimum sensitivity values in frequency response curve 1020 should be maintained within a certain range to ensure a stable frequency response of sensing device 500 or 700. In some embodiments, within the desired frequency range, the difference between the maximum and minimum sensitivity values is no greater than 40 dBV, and the ratio of the sensitivity difference to the maximum value is no greater than 0.3. In some embodiments, within the desired frequency range, the difference between the maximum and minimum sensitivity values is no greater than 10 dBV, and the ratio of the sensitivity difference to the maximum value is no greater than 0.1.

[0159] In some embodiments, the difference between the resonant frequencies corresponding to the first (or third) resonance peak and the second (or fourth) resonance peak 1021 (the frequency of the first (or third) resonance peak is represented by f0 (close to resonance peak 1011), the frequency of the second (or fourth) resonance peak 1021 is represented by f1, and the difference in resonant frequencies corresponding to the two resonance peaks is represented by frequency difference Δf2) is within a certain range. In some embodiments, the frequency difference Δf2 is within the range of 1000-6000 Hz, and the ratio of the frequency difference Δf2 to f0 is within the range of 0.2-0.65. In some embodiments, the frequency difference Δf2 is within the range of 3000-5000 Hz, and the ratio of the frequency difference Δf2 to f0 is within the range of 0.3-0.5.

[0160] Compared to frequency response curve 1010, frequency response curve 1020 exhibits a higher and more stable sensitivity improvement (i.e., difference, represented by ΔV3) within the frequency range within the resonant frequency f1 corresponding to the second (or fourth) resonance peak 1021. In some embodiments, the improvement ΔV3 is within the range of 10 dBV to 60 dBV. In some embodiments, the improvement ΔV3 is within the range of 15 dBV to 40 dBV.

[0161] For the sensor device 700, in some embodiments, the frequency corresponding to the fourth resonance peak 1021 (i.e., the fourth resonant frequency) is a mid-low frequency, and the frequency corresponding to the third resonance peak (i.e., the third resonant frequency) is a mid-high frequency. In some embodiments, the difference between the minimum sensitivity value of the frequency response curve 1020 within the frequency range up to the resonant frequency f1 and the peak value of the fourth resonance peak is no greater than 30 dBV, and the ratio thereof is no greater than 0.2.

[0162] In some embodiments, the frequency response of the sensing device 500 or 700 can be described by one or more of the parameters related to the curve 1020, such as the peak value and frequency of the primary resonance peak, the peak value and frequency of the secondary resonance peak 1021, the Q value, Δf2, ΔV3, the ratio of Δf2 to f0, the ratio of the maximum sensitivity to the minimum sensitivity within the desired frequency range, the first-order coefficient, the second-order coefficient, the third-order coefficient of the equation determined by fitting the frequency response curve, etc. In some embodiments, the frequency response of the sensing device 500 or 700 can be related to the properties of the filled liquid and / or the parameters of the transducer unit. In some embodiments, to obtain the ideal output frequency response of the sensing device 500 or 700 (e.g., the frequency response curve 1020), the range of the parameters affecting the frequency response listed above (also known as frequency response influencing factors, including the properties of the filled liquid and / or the parameters of the transducer unit) can be determined by computer simulation, phantom experiments, etc., and then compared with the range of the parameters affecting the frequency response. Figure 9 The methods described are the same or similar and will not be repeated here.

[0163] Figure 11is a schematic diagram of a sensing device to be filled with liquid according to some embodiments of the present application.

[0164] like Figure 11 As shown, the sensing device 1100 includes a housing 1110, a transducer unit 1120, a processing circuit 1130 and a PCB 1140. At least one through-hole may be provided on the upper surface of the housing 1110 of the sensing device 1100. The through-hole may connect the outside world and the accommodating cavity of the sensing device 1100. Liquid may be injected into the accommodating cavity of the sensing device 1100 through the at least one through-hole. In some embodiments, the through-hole may include a liquid injection hole 1111 and an exhaust hole 1112. Liquid may be injected into the accommodating cavity of the sensing device 1100 through the liquid injection hole 1111. At the same time, the air in the accommodating cavity may be discharged through the exhaust hole 1112 to ensure that the liquid can completely fill the accommodating cavity, the transducer unit 1120 and the processing circuit 1130 are immersed in the liquid, and there are no bubbles. Optionally, the through-hole may only include the liquid injection hole 1111. In a vacuum environment, liquid is injected into the accommodating cavity of the sensor device 1100 through the liquid injection hole 1111, and the liquid can completely fill the accommodating cavity. The transducer unit 1120 and the processing circuit 1130 are immersed in the liquid without bubbles.

[0165] In some embodiments, when sensing device 1100 is filled with liquid but contains no bubbles, sensing device 1100 is similar to sensing device 500. Due to the viscosity of the liquid, it can increase the damping of transducer unit 1120, thereby reducing the Q value of the resonance peak (also known as the first resonance peak, i.e., the peak corresponding to the natural resonant frequency of transducer unit 1120) of sensing device 1100. Furthermore, liquid is not easily compressed and may exhibit excessive stiffness and overdamping. In this case, the additional resonance peak (i.e., the second resonance peak) formed by the addition of liquid has a higher frequency and may be closer to the first resonance peak of sensing device 1100. The first and second resonance peaks may at least partially overlap, resulting in a lower flatness of the frequency response curve.

[0166] In some embodiments, by adjusting the viscosity or density of the liquid filled in the sensor device 1100 (for example, by selecting liquids of different densities and viscosities or adding specific agents to adjust the density or viscosity), the Q value of the resonance peak corresponding to the transducer unit 1120 in the sensor device 1100 can be adjusted within a certain range. For example, within a certain range, the greater the kinematic viscosity of the liquid, the smaller the Q value. In some embodiments, the density of the liquid can be 0.6-2 kg / m 3 In some embodiments, the density of the liquid may be 0.8-1.0 kg / m 3 .

[0167] In some embodiments, the kinematic viscosity of the liquid may be 0.1-5000 cSt. In some embodiments, the kinematic viscosity of the liquid may be 0.5-500 cSt. In some embodiments, the kinematic viscosity of the liquid may be 50-200 cSt.

[0168] In some embodiments, the liquid filling the accommodating cavity may include bubbles. The bubbles have a certain volume. For example, the ratio of the bubbles to the volume of the accommodating cavity of the sensing device 1100 may be any value between 5% and 95%. The number of bubbles may be 1, 2, 3, 4, or more, and is not specifically limited in this specification.

[0169] The bubbles can be located at different positions in the sensing device 1100. Taking a bone conduction microphone as an example, the chamber can be divided into a front chamber and a rear chamber with the plane where the cantilever beam is located as the dividing plane. In some embodiments, the bubbles can be in the front chamber. For example, the bubbles can be located in the front chamber away from the cantilever beam, close to the cantilever beam, or attached to the cantilever beam. In some embodiments, the bubbles can be in the rear chamber. In other embodiments, the bubbles can exist in the front and rear chambers at the same time. In some embodiments, in order to increase the stability of the sensing device, the bubbles can be located between the shell 1110 and the liquid. For more descriptions of bubbles located between the shell and the liquid, please refer to Figures 25A-25D etc. and their descriptions.

[0170] Bubbles can be formed by air that has not been discharged from the accommodating cavity. For example, when the amount of filling liquid is less than the volume of the accommodating cavity, bubbles will remain in the accommodating cavity. In some embodiments, bubbles can be formed by encapsulating gas in an airbag. For example, the airbag can be a film-like material (such as polyester film, nylon film, plastic film, composite film, etc.) itself or a closed capsule formed with a component inside the housing or the sensing device 1100, and the closed capsule is filled with gas. The size and shape of the airbag can be set according to the volume of the desired bubble, the volume and shape of the accommodating cavity, and / or the position of the airbag. In some embodiments, bubbles can also be formed by arranging a hydrophobic material on the inner surface of the accommodating cavity or on the surface of a component inside it. The bubbles adhere to the surface of the hydrophobic material. For example, a super-hydrophobic coating can be provided on a partial area of the inner surface of the accommodating cavity or a partial surface of a component inside it. Super-hydrophobic coating can be by fluorine-containing polymer, for example, polytetrafluoroethylene, fluorinated ethylene propylene copolymer, the copolymer of ethylene and tetrafluoroethylene, tetrafluoroethylene and perfluoroalkoxy vinyl ether copolymer etc., or polymer melt polymer, for example polyolefin, polycarbonate, polyamide, polyacrylonitrile, polyester, fluorine-free acrylate, molten paraffin etc. are made through specific process etc..The gas in bubble can be air, oxygen, nitrogen, inert gas etc. or its arbitrary combination.In certain embodiments, owing to there is certain elasticity characteristic after filling gas in air cavity, this elasticity characteristic is relevant with the air pressure in air cavity, therefore, the equivalent stiffness of air cavity can be changed by changing the air pressure in bubble, thereby changing the performance of second resonant system.

[0171] After the sensor device 1100 is filled with liquid and bubbles, it can be similar to the sensor device 700. Because bubbles are easily compressible and have low rigidity, the combined rigidity of the liquid and bubbles is low. Consequently, the resonant frequency (also called the fourth resonant frequency) corresponding to the resonant peak (also called the fourth resonant peak) of the second resonant system formed by the liquid and bubbles in the sensor device 1100 is low, and the difference between this and the natural resonant frequency (also called the third resonant frequency) of the transducer unit 1120 of the sensor device 1100 is large. This effectively controls the final output performance of the sensor device 1100, thereby significantly improving the overall sensitivity of the sensor device 1100, resulting in a flatter frequency response curve and a wider effective bandwidth (satisfying the flat frequency response condition). In some embodiments, by adjusting the ratio of the bubble volume to the liquid volume in the sensor device 1100, the position of the fourth resonant peak can be adjusted, so that the third and fourth resonant peaks fall within a certain frequency band, thereby optimizing the frequency response curve of the sensor device 1100 and making it relatively flat.

[0172] After the liquid or liquid and bubbles fill the accommodating cavity (e.g., the front cavity), the through hole on the upper surface of the housing 1110 will be blocked. In some embodiments, a sealing member can be used to seal the through hole. The sealing member can include, for example, a plug, a screw, or adhesive tape. In some embodiments, the through hole is a circular threaded hole. The sealing member can seal the at least one through hole by means of a threaded connection.

[0173] Figure 12 is a schematic diagram of an exemplary liquid-filled sensing device provided according to some embodiments of the present application.

[0174] like Figure 12 As shown, the sensing device 1200 can be a liquid-filled bone conduction microphone, including a housing 1210, a transducer unit 1220, a processing circuit 1230 and a PCB substrate 1240. The accommodating cavity of the housing 1210 is filled with liquid 1250. The transducer unit 1220 includes a piezoelectric layer 1221. The transducer unit 1220 and the processing circuit 1230 are connected by a lead 1260. In some embodiments, the structure and internal components of the sensing device 1200 are the same as or similar to those of the sensing device 500 and are not described again here. At least one through hole (not shown in the figure) is provided on the metal housing of the sensing device 1200. Through the at least one through hole, the liquid 1250 (for example, silicone oil) can be filled into the cavity inside the sensing device 1200.

[0175] In some embodiments, the housing 1210 may be made of metal, plastic, glass, etc. In some embodiments, the housing 1210 may be made of a transparent material. Through the transparent housing, it is possible to observe whether the internal cavity of the sensor device 1200 is filled with liquid, whether there are bubbles, etc.

[0176] It should be noted that the above description of the sensor device 1200 is merely illustrative and does not limit this specification to the embodiments described. It is understood that those skilled in the art, after understanding the principles of the system, may arbitrarily combine its structures and modules, or form subsystems that connect to other modules without departing from these principles. For example, the first resonant system 530 or the second resonant system 740 in the form of a liquid or a liquid and bubbles may also be incorporated into an audio output device, such as a speaker, to improve the speaker's frequency response.

[0177] Figure 13 1 is a frequency response curve of the sensing device before and after being partially filled with liquid according to some embodiments of the present application.

[0178] like Figure 13As shown, frequency response curve 1310 represents the frequency response curve of a sensor device (e.g., sensor device 1200) filled with liquid (e.g., silicone oil with a kinematic viscosity of 0.65 cSt). Frequency response curve 1320 represents the frequency response curve of the sensor device after the liquid is removed from the sensor device, leaving only a portion of the liquid (e.g., an oil film). In some embodiments, the front chamber of the sensor device is completely filled with liquid, while the rear chamber is partially filled with liquid. The volume of the rear chamber filled with liquid can range from 1% to 90% of the volume of the front chamber.

[0179] It can be seen that when the sensor is filled with liquid (for example, the front chamber is fully filled with liquid and the rear chamber is partially filled with liquid), compared to when only some liquid remains (for example, an oil film is present), the sensitivity of the sensor device is significantly and steadily improved in the low-frequency, mid-low-frequency, or mid-high frequency bands (for example, within the frequency bands less than 7000 Hz, 5000 Hz, 3000 Hz, 1000 Hz, or 500 Hz). In some embodiments, the sensitivity improvement can reach 10-50 dBV.

[0180] Although the sensitivity of the sensor device is greatly improved after being filled with liquid, it is in an over-damped or over-rigid state, with excessive suppression near the mid-frequency, causing the frequency response curve to drop rapidly, and the peak at the natural resonant frequency of the transducer unit in the sensor device is suppressed. In order to avoid excessive suppression of the mid-frequency due to over-damping, a certain volume of bubbles can be retained in the shell. The second resonant system 740 formed by the liquid and bubbles will have less stiffness or damping than the first resonant system 530 filled with liquid (for example, silicone oil), which can reduce the suppression of the mid-frequency.

[0181] Figure 14 1 is a frequency response curve of a sensor device with a small-sized accommodating cavity before and after being filled with liquid according to some embodiments of the present application.

[0182] The sensing device (e.g., sensing device 1200) is formed by filling the receiving cavity of the sensing device (e.g., sensing device 1100) with liquid. In this embodiment, the receiving cavity of the sensing device is a small-sized receiving cavity. In some embodiments, the length, width, and height of the receiving cavity of the sensing device are 0.5-10 mm, 0.5-10 mm, and 0.3-10 mm, respectively.

[0183] For example, in this embodiment, the accommodating cavity of the sensor device has a relatively small size: 3.76mm×2.95mm×0.8-0.85mm. Figure 14As shown, frequency response curve 1410 is the frequency response curve of the sensor device when the accommodating chamber is not filled with liquid. Frequency response curve 1420 is the frequency response curve of the sensor device when the accommodating chamber is fully filled with liquid (e.g., silicone oil with a kinematic viscosity of 0.65 cSt). Frequency response curve 1430 is the frequency response curve of the sensor device when only the rear chamber is partially filled with liquid. Frequency response curve 1440 is the frequency response curve of the sensor device when only the oil film remains on the surface of the transducer element (e.g., cantilever beam).

[0184] Combining frequency response curves 1410-1440, it can be seen that for a small-sized accommodating cavity, completely filling it with liquid (corresponding to curve 1420) does not increase the sensitivity of the sensor device. When the small-sized accommodating cavity is filled with liquid, the additional resonant frequency of the liquid is very high, preventing it from resonating before the natural resonant frequency (first or third resonant frequency) of the transducer unit. Furthermore, the introduction of liquid also increases stiffness and damping, suppressing the vibration of the transducer unit and reducing the output of the sensor device. When only some liquid remains in the rear cavity (corresponding to curve 1430), it can be considered that a large bubble has been introduced into the accommodating cavity of the sensor device. Because bubbles are easily compressible and have low stiffness, the combined stiffness of the liquid and bubbles is low. The resonant frequency (also called the fourth resonant frequency) corresponding to the resonant peak (also called the fourth resonant peak) of the second resonant system formed by the liquid and bubbles in the sensor device is low, and the difference between this and the natural resonant frequency (also called the third resonant frequency) of the transducer unit of the sensor device is large. Therefore, the sensitivity of the sensor device is significantly improved over a wide frequency band.

[0185] Figure 15 These are frequency response curves of a sensing device with a large-sized accommodating cavity provided in some embodiments of the present application when the cavity is not filled with liquid, partially filled with liquid, or when an oil film exists in the accommodating cavity.

[0186] The sensing device (e.g., sensing device 1200) is formed by filling the receiving cavity of the sensing device (e.g., sensing device 1100) with liquid. In this embodiment, the receiving cavity of the sensing device is a large-sized receiving cavity. In some embodiments, the length, width, and height of the receiving cavity of the sensing device are 1-30 mm, 1-30 mm, and 0.5-30 mm, respectively. Optionally, the receiving cavity of the sensing device has a larger size. In some embodiments, the length, width, and height of the receiving cavity of the sensing device are 10-200 mm, 10-100 mm, and 10-100 mm, respectively.

[0187] As previously mentioned, a sensor device filled with silicone oil in a small cavity can be overdamped or overstiff, resulting in excessive mid-frequency suppression, a rapid drop in the frequency response curve, and complete suppression of the resonance peak at the resonant frequency of a sensor device without liquid. Increasing the cavity size can improve the sensor's mid-frequency output, reduce the liquid's suppression of the sensor's mid-frequency response, and flatten the sensor's frequency response curve.

[0188] like Figure 15 As shown, frequency response curves 1510 and 1520 respectively represent the frequency response curves of a large-sized accommodating cavity not filled with liquid and partially filled with liquid (for example, silicone oil with a kinematic viscosity of 0.65 cst) or with an oil film in the accommodating cavity.

[0189] It can be seen that when the chamber is partially filled with liquid or an oil film exists in the chamber (corresponding to curve 1520), the frequency response sensitivity of the sensor device is improved compared to when the chamber is not filled with liquid (corresponding to curve 1510). In some embodiments, the improvement is 10-40 dBV.

[0190] Figure 16 is a schematic diagram of a liquid- and bubble-filled sensing device provided according to some embodiments of the present application.

[0191] Since the inside of the bubble is gas (such as air), its stiffness, mass, and damping are quite different from those of the liquid. Therefore, by controlling the size and position of the introduced bubble, the second resonant system 740 (i.e., the additional spring-mass-damping system) of the sensing device (e.g., sensing device 1200) can be adjusted, thereby effectively controlling the final output performance of the sensing device, making the frequency response relatively flat (e.g., peak-to-valley fluctuation less than 5dBV, 10dBV, 15dBV, etc.), and the effective bandwidth (satisfying the flat frequency response condition) covering a certain range (e.g., 20Hz-8K Hz), while the overall sensitivity is improved to a certain extent (e.g., 10-50dBV).

[0192] In this embodiment, the accommodating cavity of the sensor device is a large-sized accommodating cavity. In some embodiments, the accommodating cavity size can be 10mm×7mm×1-4mm. Exemplarily, the accommodating cavity size of the sensor device is 10mm×7mm×1mm.

[0193] In some embodiments, the bubbles may have different sizes and the positions of the bubbles in the receiving chamber of the sensor device may also be different. Figure 16 As shown, the bubbles can be small bubbles (for example, the volume ratio of the bubbles to the accommodating cavity is 10% or less), medium or large bubbles (for example, the volume ratio of the bubbles to the accommodating cavity is 10% to 90%), etc. The bubbles can be located in the front cavity of the accommodating cavity of the sensing device (away from the cantilever beam, close to or attached to the cantilever beam, etc.), the rear cavity, or both the front cavity and the rear cavity. For more details about the different positions of the bubbles, please refer to the description elsewhere in this application specification, such as Figures 18A-18D and its description.

[0194] Just as an example, Figure 16As shown, after the accommodating cavity of the sensing device 1610 is filled with liquid, there is a small bubble in the corner, and the volume of the bubble is about 2%-10% of the volume of the liquid. There are no bubbles near the transducer unit (for example, the cantilever beam). After the accommodating cavity of the sensing device 1620 is filled with liquid, the volume of the bubble is about 10%-20% of the volume of the liquid, and the transducer unit area is not covered. At this time, the transducer unit is completely soaked in silicone oil. After the accommodating cavity of the sensing device 1630 is filled with liquid, the volume of the bubble is about 20%-50% of the volume of the liquid, and the transducer unit area is not covered. At this time, the transducer unit is completely soaked in silicone oil. After the accommodating cavity of the sensing device 1640 is filled with liquid, the volume of the bubble is about 50%-90% of the volume of the liquid, covering the transducer unit area. At this time, the transducer unit is not completely soaked in silicone oil.

[0195] Figure 17 1 is a frequency response curve of a sensing device provided in some embodiments of the present application, wherein the liquid in the accommodating chamber contains bubbles of different sizes.

[0196] In this embodiment, the receiving cavity of the sensor device (e.g., sensor device 1200) is a large-sized receiving cavity. In some embodiments, the receiving cavity dimensions may be 10 mm × 7 mm × 1-4 mm. For example, the receiving cavity dimensions of each sensor device are 10 mm × 7 mm × 1 mm.

[0197] like Figure 17 As shown, curve 1710 represents the frequency response curve of the sensor device (e.g., sensor device 1100) that is not filled with silicone oil. Curve 1720 represents the frequency response curve of the sensor device (e.g., sensor device 1100) that is not filled with silicone oil. Figure 16 The frequency response curve of the sensor device for small bubbles is shown in FIG. Curve 1730 represents the frequency response curve of the sensor device for small bubbles. Figure 16 The frequency response curve of the sensor device for small and medium-sized bubbles is shown in FIG. Curve 1740 represents the frequency response curve of the sensor device for small and medium-sized bubbles. Figure 16 The frequency response curve of the sensing device for a medium-sized bubble is shown.

[0198] Frequency response curves 1710-1740 show that when bubbles do not cover the transducer element (e.g., a piezoelectric transducer), the sensitivity of the sensor device increases as the bubble volume increases. For example, compared to a sensor device containing small bubbles (corresponding to curve 1720), a sensor device containing small or medium-sized bubbles (corresponding to curve 1730) has a sensitivity improvement of approximately 5-30 dBV in low-frequency, mid-low-frequency, or mid-high frequency bands (e.g., within the frequency bands below 7000 Hz, 5000 Hz, 3000 Hz, 1000 Hz, or 500 Hz). In some embodiments, a low-frequency roll-off occurs in even lower frequency bands (e.g., below 5000 Hz, below 3000 Hz, 500 Hz, or 200 Hz). Compared with the sensor device containing small and medium-sized bubbles (corresponding curve 1730), the sensor device containing medium-sized bubbles (corresponding curve 1740) has a sensitivity improvement of approximately 5-30dBV in the frequency band before low frequency or medium-low frequency or medium-high frequency (for example, within the frequency band less than 7000Hz, 5000Hz, 3000Hz, 1000Hz or 500Hz).

[0199] Figures 18A-18D Schematic diagram of a sensing device for bubbles in a filled liquid at different positions according to some embodiments of the present application.

[0200] like Figure 18A Taking the sensor device as a bone conduction microphone 1810 as an example, the transducer unit 1812 can include a cantilever beam. The housing of the bone conduction microphone 1810 can be divided into a front chamber 1813 and a rear chamber 1814, using the plane where the transducer unit 1812 is located as a dividing plane. In some embodiments, the space formed by the base 1811 and the plane where the transducer unit 1812 is located can form the rear chamber 1814. In some embodiments, the space formed by the base 1811, the plane where the transducer unit 1812 is located, and part of the housing of the sensor device 1810 can form the rear chamber. The front chamber 1813 can be the space within the housing of the bone conduction microphone 1810 excluding the rear chamber 1814.

[0201] Figure 18A The front chamber 1813 and the rear chamber 1814 are filled with liquid 1815. Bubbles 1816 are located in the front chamber 1813, away from the transducer unit 1812. Bubbles 1816 can be located in the middle or in a corner of the front chamber 1813. Bubbles 1816 can be small (e.g., the volume ratio of the bubble to the front chamber is 10% or less), medium, or large (e.g., the volume ratio of the bubble to the front chamber is 10% to 90%), etc.

[0202] Figure 18B The structure and Figure 18AThe base 1821 and the transducer unit 1822 form a rear cavity 1824. The space in the housing cavity of the bone conduction microphone 1820 other than the rear cavity 1824 is a front cavity 1823. Both the front cavity 1823 and the rear cavity 1824 are filled with liquid 1825. Bubbles 1826 are located in the front cavity 1823 and are attached to or close to the transducer unit 1822. Bubbles 1826 can be small bubbles (for example, the volume ratio of the bubbles to the front cavity is 10% or less), medium or large bubbles (for example, the volume ratio of the bubbles to the front cavity is 10% to 90%), etc.

[0203] Figure 18C The structure and Figure 18A or Figure 18B Similar. The base 1831 and the transducer unit 1832 form a rear cavity 1834. The space in the accommodating cavity of the bone conduction microphone 1830 except the rear cavity 1834 is the front cavity 1833. Both the front cavity 1833 and the rear cavity 1834 are filled with liquid 1835. The bubble 1836 is located in the rear cavity 1834. The bubble 1836 can be located in the middle or corner of the rear cavity 1834. The bubble 1836 can be a small bubble (for example, the volume ratio of the bubble to the rear cavity is 10% or less), a medium or large bubble (for example, the volume ratio of the bubble to the rear cavity is 10% to 90%), etc.

[0204] Figure 18D The structure and Figure 18A 、 Figure 18B or Figure 18C Similarly, the base 1841 and the transducer unit 1842 form a rear cavity. In this case, only the transducer unit 1842 in the cavity of the bone conduction microphone 1840 contains liquid 1843 (e.g., an oil film). This suggests that the cavity of the bone conduction microphone 1840 contains large bubbles (e.g., a bubble-to-cavity volume ratio exceeding 90%), while the cavity is filled with very little liquid.

[0205] It should be noted that the above description of the sensor device is only an example description and does not limit this specification to the scope of the embodiments. It is understandable that for those skilled in the art, after understanding the principle of the system, it is possible to arbitrarily adjust its structure and composition without deviating from this principle. Such variations are all within the scope of protection of this application. For example, 18A to 18D The transducer unit may also include a diaphragm. The plane where the diaphragm is located can separate the accommodating cavity into a front cavity and a rear cavity. For example, 18A to 18D The transducer unit can also include a piezoelectric beam and a diaphragm (such as Figure 28B The transducer unit 2520 is shown).

[0206] Figure 19These are frequency response curves of bubbles in a filling liquid at different positions within a chamber of a sensor device according to some embodiments of the present application.

[0207] When the liquid filled in the accommodating chamber of the sensor device contains bubbles of different sizes, the output performance of the corresponding spring (Km3, Km4)-mass (Mm4)-damping (Rm3, Rm4) systems is also different.

[0208] like Figure 19 As shown, curve 1910 represents the frequency response curve of a sensing device (e.g., sensing device 1100) whose accommodating chamber is not filled with liquid. Curve 1920 represents the frequency response curve of a sensing device whose front chamber contains liquid (e.g., silicone oil) and large bubbles, and the bubbles are far away from the transducer unit, while the rear chamber contains liquid. Curve 1930 represents the frequency response curve of a sensing device whose front chamber contains air and the rear chamber contains liquid. Curve 1940 represents the frequency response curve of a sensing device whose front and rear chambers are both filled with liquid, and bubbles are present in the rear chamber. Curve 1950 represents the frequency response curve of a sensing device whose transducer unit is only covered by a liquid film.

[0209] Combining frequency response curves 1910-1950, it can be seen that when bubbles are introduced, regardless of whether the bubbles are located in the front cavity or the rear cavity, and whether or not they are in contact with the transducer unit, the sensitivity of the sensing device can be improved to a certain extent (e.g., 10-60dBV, 10-40dBV, 15-40dBV, etc.) in the low frequency, mid-low frequency, or mid-high frequency band (e.g., within the frequency band less than 7000Hz, 5000Hz, 3000Hz, 1000Hz, or 500Hz). The magnitude of the improvement is also related to the size and / or location of the bubbles. For example, combining frequency response curves 1920 and 1930, it can be seen that when the bubbles are located in the front cavity and are not in contact with the transducer unit, the sensitivity gradually increases with the increase of bubbles.

[0210] In addition to the gain in sensitivity at low, medium, and medium-high frequencies, different bubble-liquid combinations also have different effects on higher frequencies. For example, when bubbles are present in the rear chamber, the higher frequencies are less suppressed.

[0211] Figure 20 These are frequency response curves before and after the sensing device is filled with liquid, provided according to some embodiments of the present application.

[0212] like Figure 20 As shown, frequency response curves 2010 and 2020 are frequency response curves of a sensor device not filled with liquid (eg, sensor device 1100) and a sensor device filled with liquid with bubbles in the back cavity, respectively.

[0213] Combining frequency response curves 2010 and 2020, it can be seen that the liquid-filled sensor device has a resonance peak in the frequency range of 2000-20000 Hz. In contrast, a sensor device filled with liquid and introducing bubbles in the back cavity (e.g., small bubbles (e.g., the volume ratio of bubbles to the back cavity is 10% or less), medium or large bubbles (e.g., the volume ratio of bubbles to the back cavity is 10% to 90%)) has a gain of approximately 10-40 dBV in the low-frequency, mid-low-frequency, or mid-high frequency band (e.g., within the frequency band less than 7000 Hz, 5000 Hz, 3000 Hz, 1000 Hz, or 500 Hz). In some embodiments, the gain in the low-frequency band is 20-25 dBV. The spring (Km3, 4)-mass (Mm4)-damping (Rm3, 4) system composed of the bubbles and liquid forms a resonance in the low-frequency band, which significantly improves the gain of the sensor device in this band. Furthermore, because the additional damping and stiffness of the spring (Km3, 4)-mass (Mm4)-damper (Rm3, 4) system suppresses the vibration of the sensor device, the Q value of the corresponding resonance peak (e.g., the first or third resonance peak) at the sensor device's resonant frequency (here, the mid-frequency) is significantly reduced. Furthermore, by adjusting the combination of bubbles and liquid, the characteristics of the device's additional spring (Km3, 4)-mass (Mm4)-damper (Rm3, 4) can be adjusted, shifting the sensor device's resonant frequency (e.g., the first or third resonant frequency) forward or backward.

[0214] In some embodiments, bubbles of a certain size are set in the front cavity and the rear cavity, so that a larger gain can be achieved in the low-frequency part, and the intermediate frequency can suppress the Q value of the resonance peak (first or third resonance peak) of the transducer unit in the sensing device without suppressing the sensitivity of other areas outside the resonance peak area.

[0215] Figure 21 is a schematic diagram of an exemplary sensing device including droplets according to some embodiments of the present application.

[0216] like Figure 21 As shown, taking a bone conduction microphone as an example, the structure of the sensor device 2100 is similar to Figures 18A-18CThe structure of the bone conduction microphones 1810-1830 in the sensor device 2100 is shown. The sensor device 2100 includes a shell 2110, a transducer unit 2120, a droplet 2130, and a substrate 2140. The droplet 2130 is provided in the accommodating cavity of the shell 2110. The substrate 2140 and the transducer unit 2120 constitute a rear cavity 2111. The space in the accommodating cavity in the shell 2110 of the sensor device 2100 other than the rear cavity 2111 is the front cavity 2112. The droplet 2130 can be located at any position on the surface of the transducer unit 2120, so that at least a portion of the transducer unit 2120 is connected to the shell 2110 through the droplet 2130. The droplet 2130 can be equivalent to a spring-mass-damper system (for example, the first resonant system 530 or the second resonant system 740). The droplet 2130 can adjust the vibration characteristics of the transducer unit 2120 so that its original resonant frequency (for example, the first or third resonant frequency) changes, while the Q value is in an appropriate range. Moreover, due to the existence of a newly added resonant peak (for example, the second or fourth resonant peak), the sensing device 2100 has a higher sensitivity.

[0217] Exemplarily, a droplet 2130 is present in the front chamber 2112. The droplet 2130 is located between the transducer unit 2120 and the housing 2110, with its upper and lower portions connected to the transducer unit 2120 and the housing 2110, respectively. In some embodiments, the volume of the droplet 2130 may be 1% to 80% of the volume of the front chamber. In some embodiments, the volume of the droplet 2130 may be 20% to 30% of the volume of the front chamber. Alternatively, the droplet 2130 may be located in the rear chamber 2111. In some embodiments, the volume of the droplet 2130 may be 5% to 80% of the volume of the rear chamber. In some embodiments, the volume of the droplet 2130 may be 20% to 30% of the volume of the rear chamber.

[0218] The droplets 2130 may be formed by directly adding the droplets into the accommodating cavity (eg, the front cavity or the rear cavity), or by other methods, such as film wrapping.

[0219] Figure 22 is a schematic diagram of an exemplary sensing device including droplets according to some embodiments of the present application.

[0220] Figure 22 The structure of the sensor device 2200 is Figure 21 Similar. Figure 22As shown, the sensing device 2200 includes a shell 2210, a transducer unit 2220, a droplet 2230, and a substrate 2240. The housing cavity of the shell 2210 is provided with the droplet 2230. The substrate 2240 and the transducer unit 2220 constitute a rear cavity 2211. The space other than the rear cavity 2211 in the housing cavity within the shell 2210 of the sensing device 2200 is the front cavity 2212. The droplet 2230 can be located at any position on the surface of the transducer unit 2220, so that at least a portion of the transducer unit 2220 is connected to the shell 2210. In this embodiment, the droplet 2230 includes bubbles 2250. The bubbles in the droplet 2230 can be formed by adding gas to the droplet or other methods (for example, film wrapping, etc.). In some embodiments, the droplet 2230 forms a hollow droplet due to the presence of the bubble 2250. In some embodiments, the size and position of the hollow droplet are the same as or similar to those of the droplet 2130, and will not be further described here. The droplet 2230 and the bubble 2250 can be equivalent to a spring-mass-damper system (e.g., the first resonant system 530 or the second resonant system 740). By adding the bubble 2250, the stiffness and / or damping of the introduced spring-mass-damper system can be adjusted over a wider range, allowing the newly added resonant frequency (e.g., the second or fourth resonant frequency) and the device Q value to be adjusted over a wider range.

[0221] In some embodiments, a gap (e.g., a slit, slot, hole, etc.) exists between the transducer unit (e.g., a cantilever beam, a suspended membrane, etc.) and the housing of the sensing device. In some embodiments, an additional resonant system (e.g., a first resonant system 530 or a second resonant system 740) of the sensing device can be disposed in the gap. The additional resonant system can adjust the original vibration characteristics of the transducer unit 2220, causing the original resonant frequency (e.g., the first or third resonant frequency) to change while maintaining the Q value within an appropriate range. A new resonant system can also be introduced, and the presence of a newly added resonant peak (e.g., the second or fourth resonant peak) can provide the sensing device with higher sensitivity.

[0222] Figure 23A is a schematic diagram of an exemplary sensing device including a liquid film according to some embodiments of the present application.

[0223] Figure 23A The structure of the sensor device 2300 is Figure 21 and 22 Similar. Figure 23AAs shown, the sensing device 2300 includes a housing 2310, a transducer unit 2320, a liquid film 2330, and a substrate 2340. The substrate 2340 and the transducer unit 2320 form a rear cavity 2311. The space within the accommodating cavity within the housing 2310 of the sensing device 2300, excluding the rear cavity 2311, is a front cavity 2312. A gap exists between the transducer unit 2320 and the housing 2310. The liquid film 2330 can be located within the gap between the transducer unit 2320 and the housing 2310, such that at least a portion of the transducer unit 2320 is connected to the housing 2310. In some embodiments, the thickness of the liquid film 2330 can be less than, equal to, or greater than the thickness of the transducer unit 2320.

[0224] Figure 23B is a schematic diagram of an exemplary sensing device including a liquid film according to some embodiments of the present application.

[0225] Figure 23B The structure of the sensor device 2350 is Figure 21-22 and Figure 23A Similar. Figure 23B As shown, the sensing device 2350 includes a housing 2360, a transducer unit 2370, a liquid film 2380, and a substrate 2390. The substrate 2390 and the transducer unit 2370 form a rear cavity 2361. The space within the housing 2360 of the sensing device 2350, excluding the rear cavity 2361, is a front cavity 2362. There are multiple gaps between the transducer unit 2370 and the housing 2360. The liquid film 2380 can be located within the gaps within the transducer unit 2370 itself and the gaps between the transducer unit 2370 and the housing 2360, thereby connecting various parts of the transducer unit 2370 and at least a portion of the transducer unit 2370 to the housing 2360. In some embodiments, the thickness of the liquid film 2380 can be less than, equal to, or greater than the thickness of the transducer unit 2370.

[0226] Figure 24A is a schematic diagram of an exemplary sensing device including a liquid film according to some embodiments of the present application.

[0227] Figure 24A The structure of the sensor device 2400 is Figure 21-22 and Figures 23A-23B Similar. Figure 24AAs shown, the sensor device 2400 includes a housing 2410, a transducer unit 2420, a liquid film 2430, and a substrate 2440. The substrate 2440 and the transducer unit 2420 form a rear cavity 2411. The space within the accommodating cavity within the housing 2410 of the sensor device 2400, excluding the rear cavity 2411, is a front cavity 2412. A gap exists between the transducer unit 2420 and the housing 2410. The liquid film 2430 can be located within the gap between the transducer unit 2420 and the housing 2410, so that at least a portion of the transducer unit 2420 is connected to the housing 2410. Furthermore, the liquid film 2430 also covers at least a portion of the surface of the transducer unit 2420. In this embodiment, the liquid film 2430 also covers the upper surface of the transducer unit 2420, thereby further improving the performance of the sensor device 2400.

[0228] Figure 24B is a schematic diagram of an exemplary sensing device including a liquid film according to some embodiments of the present application.

[0229] Figure 24B The structure of the sensor device 2450 is Figure 21-22 、 Figures 23A-23B and Figure 24A Similar. Figure 24B As shown, the sensor device 2450 includes a housing 2460, a transducer unit 2470, a liquid film 2480, and a substrate 2490. The substrate 2490 and the transducer unit 2470 form a rear cavity 2461. The space within the accommodating cavity within the housing 2410 of the sensor device 2400, excluding the rear cavity 2461, is a front cavity 2462. A gap exists between the transducer unit 2470 and the housing 2460. The liquid film 2480 can be located within the gap between the transducer unit 2470 and the housing 2460, so that at least a portion of the transducer unit 2470 is connected to the housing 2460. Furthermore, the liquid film 2480 also covers at least a portion of the surface of the transducer unit 2470. In this embodiment, the liquid film 2480 also covers the upper and lower surfaces of the transducer unit 2470, thereby further improving the performance of the sensor device 2450.

[0230] Figure 25ASchematic diagram of the mechanical structure of an exemplary sensing device according to some embodiments of the present application. In some embodiments, the sensing device 2500 can be regarded as adding an additional resonant system on the basis of the transducer unit 2520. For example, in this embodiment, the shell 2510 can be equivalent to mass (Ms). The transducer unit 2520 can be equivalent to a spring (Km')-mass (Mm)-damping (Rm') system. The mass (Mm) can be provided by the mass of the transducer unit 2520 itself and the equivalent additional mass of the liquid 2540 on the transducer unit 2520. The spring (Km')-damping (Rm') can be jointly determined by the equivalent spring damping of the rear cavity 2502 (i.e., the equivalent spring (Ka)-damping (Ra)), the spring damping of the transducer unit 2520 itself, and the additional spring damping of the liquid 2540.

[0231] By designing liquid 2540 and air cavity 2503, a new spring (Kp')-mass (Ml)-damping (Rp') system, i.e., an additional resonant system, can be formed. Mass (Ml) is primarily provided by liquid 2540. Spring (Kp')-damping (Rp') can be determined by the stiffness and damping of the gas in front cavity 2501, the stiffness and damping of the interface between liquid 2540 and air cavity 2503 (e.g., gas-liquid interface 2550 or first flexible membrane 2555), and the stiffness and damping of liquid 2540 itself.

[0232] Liquid 2540 is in contact with transducer unit 2520, and is equivalent to an equivalent spring (K1) and damper (R1) connection formed by liquid 2540 between the transducer unit 2520. Liquid 2540 can receive vibrations of housing 2510. Liquid 2540 is connected to housing 2510 by an equivalent spring (Kl1) and damper (Rl1) formed by liquid 2540.

[0233] When the housing 2510 receives an external signal (i.e., external excitation), the signal can be transmitted to the liquid 2540 of the sensing device 2500, the transducer unit 2520, and the gas in the rear chamber 2502 through the spring (Km')-damping (Rm'), the spring (Kp)-damping (Rp), the spring (Ka)-damping (Ra), and the spring (Kl1)-damping (Rl1). For example, Figure 25A As shown, the sensing device 2500 can perform forced vibration under the action of the excitation acceleration a, and transmit the force to the transducer unit 2520 through the spring (Km')-damping (Rm'), spring (Kp)-damping (Rp), spring (Ka)-damping (Ra), and spring (Kl1)-damping (Rl1) to generate a velocity V.

[0234] In the embodiment of the present application, when the sensor device 2500 receives external stimulation, in addition to the response of the transducer unit 2520 due to inertia, the additional resonance system provided by the liquid 2540 and the air cavity 2503 also produces a corresponding response due to inertia and acts on the transducer unit 2520, resulting in an additional resonance peak on the frequency response curve of the sensor device 2500. Compared with other sensor devices without liquid 2540 and air cavity 2503, the output of the sensor device 2500 can be significantly increased. More descriptions of the effects of introducing additional resonance systems can be found elsewhere in this application, such as Figure 9 and 10 and its description.

[0235] Figures 25B-25D Schematic diagram of the structure of an exemplary sensor device according to some embodiments of the present application. Figure 25B As shown, the sensing device 2500 includes a housing 2510 , a transducer unit 2520 and a processing circuit 2530 .

[0236] The housing 2510 has a housing cavity inside. The housing cavity can be used to accommodate the transducer unit 2520 and / or the processing circuit 2530. The housing 2510 can be used to transmit external signals (such as mechanical signals, acoustic signals, etc.) so that the transducer unit 2520 senses the external signal and generates a target signal. For example, when the sensing device 2500 is a bone conduction microphone, the housing 2510 can transmit the vibration corresponding to the sound to the transducer unit 2520 based on the external sound. For more detailed descriptions of the housing, please refer to other places in this application specification, such as Figure 1 、 Figure 2 and its description.

[0237] The transducer unit 2520 can be used to convert an external signal into a target signal, such as converting a vibration signal into an electrical signal. In some embodiments, the transducer unit 2520 may include a vibration pickup structure 2521 and a base structure 2522. The base structure 2522 is fixedly connected to the inner wall of the housing 2510, and the vibration pickup structure 2521 is supported by the base structure 2522. The vibration pickup structure 2521 can be used to pick up vibrations and generate a target signal (e.g., an electrical signal). For example, the vibration pickup structure 2521 can pick up vibrations of the housing 2510 transmitted by the base structure 2522 in contact with it. For another example, when the accommodating chamber is filled with liquid, the vibration pickup structure 2521 can pick up vibrations transmitted by the liquid in contact with it (e.g., liquid 2540). The base structure 2522 can be a cylindrical structure with two through ends, one end of the cylindrical structure connected to the housing 2510 and the other end connected to the vibration pickup structure 2521. In some embodiments, the vibration pickup structure 2521 can cover one side opening of the cylindrical structure. In this way, the transducer unit 2520 can separate the accommodating cavity into a front cavity 2501 and a rear cavity 2502 located on opposite sides of the vibration pickup structure 2521. Figure 25B As shown, the vibration pickup structure 2521, the base structure 2522 and part of the shell constitute the rear cavity 2502. The space in the accommodating cavity within the shell 2510 of the sensing device 2500 except the rear cavity 2502 is the front cavity 2501. In some embodiments, the transducer unit 2520 may only include the vibration pickup structure 2521. The vibration pickup structure 2521 directly separates the accommodating cavity into a front cavity and a rear cavity located on opposite sides of the vibration pickup structure 2521. For example, the vibration pickup structure 2521 may be a piezoelectric film, and the edge of the piezoelectric film may be directly connected to the shell 2510, thereby cooperating with the shell 2510 to form a front cavity and a rear cavity. For another example, the vibration pickup structure 2521 may be a piezoelectric beam and a vibration membrane, one end of the piezoelectric beam may be directly connected to the shell 2510, and the vibration membrane may cover the surface of the piezoelectric beam, thereby separating the accommodating cavity into a front cavity and a rear cavity.

[0238] In some embodiments, at least one of the front cavity 2501 and the rear cavity 2502 is filled with liquid 2540. Liquid 2540 is in contact with the vibration pickup structure 2521. By placing liquid 2540 in contact with the vibration pickup structure 2521, when the sensing device 2500 is excited, the vibration pickup structure 2521 can not only pick up vibrations of the housing 2510, but also vibrations transmitted by the liquid 2540. As a result, in addition to the resonance peak corresponding to the natural resonant frequency of the vibration pickup structure 2521 (i.e., the first resonance peak), the frequency response curve of the sensing device 2500 also produces an additional resonance peak (i.e., the second resonance peak), thereby significantly increasing the output sensitivity of the sensing device 2500. For example, the front cavity 2501 and the rear cavity 2502 can be filled with liquid to provide an additional resonant system (e.g., the first resonant system 530) for the transducer unit 2520. The additional resonant system can provide an additional resonant peak for the transducer unit 2520, thereby improving the sensitivity of the sensing device 2500.

[0239] In some embodiments, liquid 2540 can be disposed in the front chamber 2501 (e.g., Figure 25B The sensor device 2500 shown in FIG. 25 may also be provided in the rear cavity 2502, or may be provided in both the front cavity 2501 and the rear cavity 2502 (as shown in FIG. 25). Figure 18A For ease of description, the following description uses a sensor device in which the front chamber is filled with liquid as an example, which does not limit the scope of this application. For example, liquid 2540 can be placed in the rear chamber 2502. Furthermore, the rear chamber can be provided with a flexible membrane, and liquid 2540 can be placed in the space formed by the flexible membrane and the transducer unit 2520.

[0240] In some embodiments, an air cavity 2503 (also referred to as a bubble) may be provided in the front cavity 2501. The air cavity 2503 is filled with gas (e.g., air). The liquid 2540 and the air cavity 2503 may constitute a second resonant system 740, thereby improving the sensing sensitivity of the sensing device 2500 (e.g., Figure 7-10 shown).

[0241] In some embodiments, to improve the stability of the sensing device 2500, an air cavity 2503 can be disposed between the liquid 2540 and the housing 2510 corresponding to the vibration direction of the vibration pickup structure 2521. In this case, due to the viscosity of the liquid 2540 (or the gas density being lower than the liquid density), the position of the air cavity 2503 is not easily changed, thereby improving the stability of the sensing device 2500 and facilitating its manufacture.

[0242] In some embodiments, as Figure 25BAs shown, a gas-liquid interface 2550 can be formed between the liquid 2540 and the air cavity 2503. In other words, there is no constraining structure on the upper surface of the liquid 2540. A gas-liquid interface 2550 with extremely low stiffness can be formed at the interface between the liquid 2540 and the gas. The gas-liquid interface 2550 with extremely low stiffness has a small overall additional stiffness to the transducer unit 2520 (or the vibration pickup structure 2521), thereby achieving a larger output. In this case, the sensing device 2500 can be used in application scenarios with small vibrations and no need for frequent movement.

[0243] In some embodiments, as Figure 25C As shown, a first flexible membrane 2555 can be disposed between liquid 2540 and air cavity 2503. First flexible membrane 2555 is a deformable membrane-like structure. First flexible membrane 2555 can constrain the boundaries of liquid 2540, ensuring that liquid 2540 remains in a controllable state during vibration, further ensuring the stability and reliability of sensor device 2500. In this case, sensor device 2500 can be applied in scenarios involving high excitation, complex environments, and frequent movement.

[0244] In some embodiments, the structure and material of the first flexible membrane 2555 can be designed to adjust the resonant position of the additional resonant system formed by the liquid and air cavity introduced into the sensing device 2500, as well as the resonant position of the transducer unit 2520, thereby realizing a highly sensitive sensing device within a confined liquid boundary. In some embodiments, the first flexible membrane 2555 can be a membrane structure that exhibits flexibility (e.g., high yield strength and resistance to high-temperature deterioration) and softness (e.g., low hardness and easy deformation). For example, the first flexible membrane 2555 can be made of one or more of polyimide film (PI film), polydimethylsiloxane film (PDMS film), polyurethane (PU), polyetheretherketone (PEEK), a semiconductor flexible film, silicone adhesive, silicone film, silicone gel, or a damping adhesive (e.g., acrylic damping adhesive). In some embodiments, the thickness of the first flexible membrane 2555 can range from 0.05 mm to 0.15 mm.

[0245] In some embodiments, as Figure 25DAs shown, in order to further achieve effective regulation of the resonance peak generated by the liquid 2540, a mass block 2560 can be added to the first flexible membrane 2555. For example, for the additional resonance system (i.e., the spring (Kp)-mass (Ml)-damping (Rp) system), if the mass of the mass block 2560 is increased, the mass (Ml) can be increased, thereby reducing the frequency corresponding to the additional resonance peak of the sensing device 2500 (i.e., the additional resonance frequency) (e.g., as shown in FIG. Figure 29C if the mass of the mass block 2560 is reduced, the mass (Ml) can be reduced, thereby increasing the additional resonant frequency corresponding to the additional resonant peak of the sensing device 2500.

[0246] In some embodiments, mass block 2560 can be made of one or more materials selected from metals (e.g., iron, copper, aluminum), semiconductors (e.g., silicon, graphite), and organic materials (e.g., rubber, plastic). In some embodiments, first flexible membrane 2555 and mass block 2560 can be made of the same material. In this case, first flexible membrane 2555 and mass block 2560 can be integrally formed or fabricated using a semiconductor localized etching process. In some embodiments, first flexible membrane 2555 and mass block 2560 can be made of different materials. They can be fabricated using macroscopic or semiconductor processes such as bonding, lamination, and deposition.

[0247] In some embodiments, the transducer unit 2520 may include a piezoelectric transducer. The vibration pickup structure 2521 may include a piezoelectric film or a piezoelectric beam, etc. For example, the piezoelectric film is a membrane-like component with a piezoelectric effect, and the edge of the piezoelectric film can be fixed on the base structure 2522 to form the transducer unit 2520. For another example, one end of the piezoelectric beam can be fixed on the base structure 2522 to form the transducer unit 2520. In some embodiments, the piezoelectric film or the piezoelectric beam may include at least two electrode layers (for example, a first electrode layer and a second electrode layer) and at least one piezoelectric layer, and the piezoelectric layer may be located between the first electrode layer and the second electrode layer. For more descriptions of the piezoelectric layer and the electrode layer, see Figure 2 In some embodiments, the piezoelectric film or piezoelectric beam may be a piezoelectric bimorph structure. For example, the piezoelectric layer may include a first electrode layer, a first piezoelectric layer, a second electrode layer, a second piezoelectric layer, and a third electrode layer, arranged sequentially from top to bottom.

[0248] In some embodiments, the piezoelectric film or piezoelectric beam may further include a substrate layer, which may be disposed between the electrode layer and the base structure 2522 to support the piezoelectric layer and the electrode layer. In some embodiments, the electrode layer and the piezoelectric layer may be formed on the substrate layer by coating, casting, or other processes. In some embodiments, the substrate layer may be made of one or more materials such as silicon, silicon dioxide, silicon nitride, or silicon carbide. In some embodiments, the substrate layer may be a single layer or a multilayer composite structure.

[0249] In some embodiments, the piezoelectric film may be in regular shapes such as circular, rectangular, elliptical, semicircular, polygonal, or any irregular shape. The base structure 2522 may be a cylindrical structure having a corresponding shape.

[0250] In some embodiments, when the size of the transducer unit 2520 remains unchanged and the driving force is the same, in order to further improve the output performance of the sensing device 2500 (for example, to make the vibration pickup structure 5221 produce a larger output displacement), the piezoelectric film structure can be split into multiple cantilever beam structures. In other words, the vibration pickup structure 2521 may include multiple piezoelectric beams 2523. Multiple piezoelectric beams 2523 (for example, 2, 3, 4 piezoelectric beams 2523) can be arranged on the same plane, so that the vibration pickup structure 2521 has various shapes (for example, square, circular, etc.). In this way, compared with an integral piezoelectric film, multiple piezoelectric beams 2523 can independently sense external signals, and they can output target signals as a whole, so that the whole composed of multiple piezoelectric beams 2523 can produce a larger displacement under the same external excitation, so that the vibration pickup structure 2521 can output a larger electrical signal, thereby improving the sensitivity of the sensing device 2500.

[0251] Figure 26 It is a schematic diagram of a top view of an exemplary transducer unit according to some embodiments of the present application. Figures 27A-27D yes Figure 26 AA cross-sectional view of the transducer unit. Figure 26 As shown, the plurality of piezoelectric beams 2523 can be arranged on the same plane so that the vibration pickup structure 2521 is square. A gap is formed between two adjacent piezoelectric beams in the plurality of piezoelectric beams 2523. In some embodiments, the gap between two adjacent piezoelectric beams in the plurality of piezoelectric beams 2523 is no greater than 20 μm.

[0252] In some embodiments, in order to ensure that the liquid 2540 does not flow into another chamber along the gap between the piezoelectric beams 2523 (for example, from the front chamber 2501 to the rear chamber 2502), thereby improving the stability of the sensor device 2500, a filling component 2570 may be provided at the position of the gap between the piezoelectric beams 2523. In some embodiments, the filling component 2570 may be provided at the gap between the piezoelectric beams 2523 (for example, Figure 27AAs shown), the upper surface (as Figure 27B as shown) or the lower surface (as Figure 27C For example, Figure 27D As shown, the filling member 2570 can be set simultaneously in the gap, upper surface and lower surface of the piezoelectric beam 2523.

[0253] In some embodiments, multiple piezoelectric beams 2523 can vibrate to produce resonant peaks at the same frequency. The multiple piezoelectric beams 2523 can output an electrical signal as a whole. To avoid affecting the vibration of the individual piezoelectric beams 2523, the stiffness of the filler component 2570 can be less than the stiffness of the multiple piezoelectric beams 2523. In some embodiments, the filler component 2570 can be made of one or more materials such as semiconductor metals and non-metallic materials. For example, the filler component 2570 can be made of a flexible material such as rubber, plastic, or silicone.

[0254] Figure 28A It is a schematic structural diagram of an exemplary sensing device according to some embodiments of the present application. Figure 28B yes Figure 28A Top view of the transducer unit.

[0255] In some embodiments, as Figure 28A As shown, the vibration pickup structure 2521 may include a plurality of piezoelectric beams 2523 and a vibration membrane 2524. The vibration membrane 2524 may cover the surface (for example, the upper surface or the lower surface) of the plurality of piezoelectric beams 2523 to prevent the liquid 2540 from passing through the transducer unit 2520 into another chamber. The vibration membrane 2524 may receive the vibration of the liquid 2540 and / or the shell 2510, and transmit the vibration to each piezoelectric beam 2523. In some embodiments, the vibration membrane 2524 may be made of the same or different material as the first flexible membrane 2555. For example, the vibration membrane 2524 may be made of one or more materials such as semiconductor metal materials, non-metallic materials, etc. For another example, the vibration membrane 2524 may be made of organic materials such as rubber, plastic, silicone, etc.

[0256] In some embodiments, as Figure 28B As shown, in order to improve the stability of the structure of the sensing device 2500, multiple piezoelectric beams 2523 can be flatly distributed on the same plane, and two adjacent piezoelectric beams 2523 can be arranged on opposite sides of the base structure 2522, so that the multiple piezoelectric beams 2523 are staggered.

[0257] In some embodiments, multiple piezoelectric beams 2523 can vibrate to produce resonance peaks of different frequencies. Each piezoelectric beam 2523 can output a sub-electrical signal as a separate signal acquisition unit. In some embodiments, each sub-electrical signal can be directly output to the processing circuit 2530 in the form of electrical series, parallel, or series-parallel combination. In some embodiments, each sub-electrical signal can be transmitted separately to the processing circuit 2530, and the processing circuit 2530 will perform signal processing on each sub-electrical signal separately (including but not limited to adjusting the amplitude, phase, etc.), and then perform corresponding signal fusion. More descriptions of the processing methods of the sub-electrical signals of each piezoelectric beam can be found, for example, in the PCT application entitled "MICROPHONE AND ELECTRONIC DEVICE HAVING THE SAME" and application number PCT / CN2020 / 103201, the contents of which are incorporated herein by reference.

[0258] In some embodiments, the vibration pickup structure 2521 may not include the vibration membrane 2524. In this case, to prevent the liquid 2540 from flowing from one chamber to another, the gap width between two adjacent piezoelectric beams 2523 and between the piezoelectric beam 2523 and the base structure 2522 is no greater than 20 μm.

[0259] Figure 29A is a frequency response curve of an exemplary sensing device according to some embodiments of the present application. Figure 29A As shown, curve 2910 represents the frequency response curve of the sensor device when the front cavity is not filled with liquid 2540. Curve 2920 represents the frequency response curve of the sensor device when the front cavity is filled with liquid 2540 and there is a gas-liquid interface between the liquid 2540 and the gas in the gas cavity 2503 (for example, Figure 25B The frequency response curve of the sensor device shown in Figure 1 is as follows. Figure 29A As can be seen, for the sensor device without liquid 2540, its frequency response curve 2910 has an inherent resonance peak O at higher frequencies related to the structure of its transducer unit. By filling the sensor device with liquid 2540 (corresponding to curve 2920), an additional resonance peak P (less pronounced due to damping) is generated in the sensor device at lower frequencies (e.g., 200 Hz-1500 Hz), significantly improving the sensor device's output in the mid- and low-frequency ranges. For example, under 1g excitation, the sensitivity is increased by approximately 50dBV compared to the sensor device without liquid 2540 (corresponding to curve 2910).

[0260] Figure 29B is a frequency response curve of an exemplary sensor device according to some embodiments of the present application. Figure 29B As shown, curve 2930 represents the situation where the first flexible membrane 2555 is present between the liquid 2540 and the air cavity 2503, and the sensing device (e.g., Figure 25C The frequency response curve of the sensor device shown in Figure 1 is shown in Figure 2. Figure 29B It can be seen that by filling the sensor device with liquid 2540 and using the first flexible membrane 2555 (corresponding to curve 2930), an additional resonant peak Q is generated in the lower frequency band (e.g., 200 Hz-2000 Hz), greatly improving the output of the sensor device in the low and medium frequency bands. For example, under 1g excitation, the sensitivity is improved by approximately 41dBV compared to the sensor device when not filled with liquid 2540 and using the first flexible membrane 2555 (corresponding to curve 2910).

[0261] Furthermore, the design of first flexible membrane 2555 allows for effective adjustment of the resonance peak generated by the designed liquid. For example, compared to a sensor device filled with liquid 2540 but without first flexible membrane 2555 (corresponding to curve 2920), both the inherent resonance peak (not shown) and the additional resonance peak Q shift toward higher frequencies. In some embodiments, the difference between the additional resonance peak Q and the additional resonance peak P can range from 10 Hz to 1000 Hz.

[0262] Figure 29C is a frequency response curve of an exemplary sensor device according to some embodiments of the present application. Figure 29C As shown, curve 2940 represents a sensing device (e.g., as shown in FIG. 25) provided with a liquid 2540, a first flexible membrane 2555, and a mass 2560. Figure 25D The frequency response curve of the sensor device shown in Figure 1 is shown in Figure 2. Figure 29C As can be seen, compared to providing only liquid 2540 and first flexible membrane 2555 (corresponding to curve 2930), the addition of mass block 2560 (corresponding to curve 2940) further improves the output of the sensing device, for example, by approximately 10 dBV under 1 g excitation. Furthermore, the addition of mass block 2560 increases the mass of the additional resonant system, shifting the additional resonant peak of the additional resonant system toward lower frequencies.

[0263] Figure 30A and Figure 30B is a schematic diagram of the structure of an exemplary sensing device according to some embodiments of the present application. In some embodiments, Figure 30AAs shown, the vibration pickup structure 2521 may include an electrostatic transducer (e.g., a capacitive transducer). The capacitive transducer includes at least a perforated back plate 2525 and a vibrating electrode film 2526. The vibrating electrode film 2526 and the perforated back plate 2525 are placed in parallel and close to each other, respectively constituting the two poles of the capacitor. The power supply provides voltage to the two poles of the capacitor. When there is an external vibration signal, the vibrating electrode film 2526 can vibrate based on the external vibration signal, while the perforated back plate 2525 is fixed, thereby changing the distance between the two poles of the capacitor, thereby changing the capacitance of the capacitor. When the voltage remains unchanged, the amount of electricity in the capacitor changes, thereby generating an electrical signal.

[0264] In some embodiments, as Figure 30A As shown, liquid 2540 can be disposed near a side of the vibrating electrode membrane 2526. The vibrating electrode membrane 2526 can receive vibrations transmitted by the liquid 2540 and the housing 2510. The vibrating electrode membrane 2526 can change the distance between the vibrating electrode membrane 2526 and the perforated back plate 2525, thereby changing the signal of the capacitor formed by the vibrating electrode membrane 2526 and the perforated back plate 2525, and then outputting the signal to the processing circuit 2530 for processing.

[0265] In some embodiments, as Figure 30B As shown, in order to make the frequency response of the sensor device 2500 flatter and have a smaller Q value, liquid 2540 can be disposed on the side close to the perforated back plate 2525. In this case, the liquid 2540 can penetrate through the holes in the perforated back plate 2525 and into the space between the perforated back plate 2525 and the vibrating electrode membrane 2526. The holes, the slit structure between the vibrating electrode membrane 2526 and the perforated back plate 2525 can increase the overall damping, thereby achieving damping adjustment for the sensor device 2500.

[0266] In some embodiments, air domains exist in the liquid between the perforated backplate 2525 and the vibrating electrode membrane 2526. These air domains can exist in the form of bubbles in the gap between the perforated backplate 2525 and the vibrating electrode membrane 2526. Due to the presence of the perforated backplate 2525, the air domains can be confined within the gap structure between the vibrating electrode membrane 2526 and the perforated backplate 2525. The air domains and the liquid 2540 can form an additional resonant system, providing additional resonant peaks for the transducer 2520. By adjusting the size of the air domains and / or liquid domains in the gap, the frequency response of the capacitive transducer can be adjusted. Furthermore, the liquid 2540 forms a dielectric layer between the vibrating electrode membrane 2526 and the perforated backplate 2525. By adjusting the material of the liquid 2540, parameters such as the dielectric constant of the capacitive transducer can be adjusted, thereby adjusting the sensitivity of the capacitive transducer. For example, the sensitivity of the capacitive transducer can be increased by filling the gap with a liquid 2540 having a higher dielectric constant.

[0267] Figure 31 is a frequency response curve of an exemplary sensor device including a capacitive transducer according to some embodiments of the present application. Figure 31 As shown, curve 3010 represents the frequency response curve of the sensor device including the capacitive transducer without the liquid 2540. Curve 3020 represents the sensor device with the liquid 2540 in the cavity near the side of the hole back plate 2525 (for example, Figure 30B Frequency response curve of the sensor device shown).

[0268] from Figure 31 As can be seen, by filling the sensor device 2500 with liquid 2540 (corresponding to curve 3020), an additional resonance peak M is generated in the lower frequency band, significantly improving the output of the sensor device 2500. For example, under 1g excitation, the output is increased by approximately 46dBV. Furthermore, by designing liquid 2540 in the cavity near the perforated back plate 2525, a damping effect is achieved, thereby making the frequency response curve of the sensor device 2500 relatively flat.

[0269] Figure 32 2 is a schematic diagram of an exemplary sensor device according to some embodiments of the present application. In some embodiments, due to the interaction between the gas in the cavity (e.g., the back cavity 2502) in contact with the transducer unit 2520 and the transducer unit 2520 (or the vibration pickup structure 2521) (e.g., Figure 25A As shown in the spring (Ka)-damping (Ra)), the equivalent stiffness of the gas in the cavity can affect the vibration performance of the vibration pickup structure 2521 and / or the additional resonant system. Therefore, the resonant frequency of the vibration pickup structure 2521 and / or the additional resonant system can be changed by changing the equivalent stiffness of the gas in the cavity, thereby adjusting the output performance of the sensing device 2500.

[0270] In some embodiments, the equivalent stiffness of the gas in the cavity can be changed by changing the cavity volume. Figure 32 As shown, when the front cavity 2501 is filled with liquid 2540, an air hole 2515 can be provided at the position of the shell 2510 corresponding to the rear cavity 2502, so that the rear cavity 2502 is connected to the external environment (equivalent to increasing the rear cavity 2502 to infinity), thereby reducing the equivalent stiffness of the gas in the rear cavity 2502, and then the additional resonance peak of the additional resonance system can be designed in a lower frequency band (for example, 200Hz-1500Hz), thereby obtaining a higher response output. In some embodiments, Figure 32 The sensor device 2500 shown can be applied to application scenarios that do not require the sensor device to shield air noise.

[0271] Figure 33is a schematic diagram of the structure of an exemplary sensing device according to some embodiments of the present application. In some embodiments, Figure 33 As shown, an additional gas cavity 2504 can be provided to communicate with the rear cavity 2502 that is not filled with liquid 2540 to increase the volume of the cavity, so that the equivalent stiffness of the gas in the cavity (rear cavity 2502 and gas cavity 2504) is reduced, and the additional resonance peak of the additional resonance system can be designed to be in a lower frequency band, thereby obtaining a higher response output and having a higher sensitivity. Specifically, the housing 2510 can also have a gas cavity 2504. One of the front cavity 2501 and the rear cavity 2502 is filled with liquid 2540, and the gas cavity 2504 is communicated with the other cavity in the front cavity 2501 and the rear cavity 2502 that is not filled with liquid 2540. For example, Figure 33 As shown, when the front cavity 2501 is filled with liquid 2540, the gas cavity 2504 can be connected to the rear cavity 2502. In some embodiments, the gas cavity 2504 and the rear cavity 2502 can be collectively referred to as the rear cavity. Figure 32 The sensing device shown, Figure 33 The size of the rear cavity of the sensor device shown is reduced, thereby increasing the equivalent stiffness of the gas, so that the inherent resonance peak of the vibration pickup structure 2521 and the additional resonance peak of the additional resonance system are both moved to high frequencies (such as Figure 35A In some embodiments, Figure 33 The sensor device 2500 shown can be applied to application scenarios that require the sensor device to shield air noise, are insensitive to the size of the sensor device, and require higher sensitivity.

[0272] In some embodiments, the edge of the gas cavity 2504 can be flush with the housing 2510. In other words, the gas cavity 2504 can be removed, and only the rear cavity 2502 (e.g., Figures 25B-25D At this time, relative to Figure 33 In the sensing device shown, as the size of the back cavity decreases, the equivalent stiffness of the gas in the back cavity increases, causing the resonance peak of the vibration pickup structure 2521 and / or the additional resonance system to continue to move toward high frequencies (e.g. Figure 35B In some embodiments, Figures 25B-25D The sensor device 2500 shown can be applied to application scenarios where there is a requirement for the sensor device to shield air noise, the sensor device is sensitive to size, and the frequency of the signal to be acquired is relatively high.

[0273] In some embodiments, since the gas pressure in the gas cavity 2504 and the back cavity 2502 can affect the equivalent stiffness of the gas therein, the output performance of the sensing device 2500 can be adjusted by adjusting the gas pressure in the gas cavity 2504 and the back cavity 2502. For example, the gas pressure in the gas cavity 2504 and the back cavity 2502 can be reduced to reduce the equivalent stiffness of the gas, thereby shifting the resonance peak of the vibration pickup structure 2521 and / or the additional resonant system to a lower frequency. In some embodiments, porous dielectric materials, metamaterials, etc. can be provided in the gas cavity 2504 and / or the back cavity 2502 to achieve the effect of increasing the virtual cavity volume, thereby reducing the equivalent stiffness of the gas and shifting the resonance peak of the vibration pickup structure 2521 and / or the additional resonant system to a lower frequency. Exemplary porous dielectric materials include porous aluminum foam, ceramics, and carbon foam. Exemplary metamaterials include left-handed materials, photonic crystals, supermagnetic materials, and metallic water.

[0274] Figure 34 is a schematic diagram of the structure of an exemplary sensing device according to some embodiments of the present application. In some embodiments, Figure 34 As shown, the equivalent stiffness of the gas in the rear cavity 2502 can be changed by covering the second flexible film 2580 on the air hole 2515, thereby adjusting the output performance of the sensing device. For example, compared with the sensing device without the air hole 2515 (such as Figure 25B In the sensor device 2500 shown in FIG. 2 , by covering the air holes 2515 with a second flexible film 2580, the interaction between the gas and the transducer unit 2520 can be reduced, thereby reducing the equivalent stiffness of the gas and shifting the resonance peak of the vibration pickup structure 2521 and / or the additional resonance system to a lower frequency. For another example, compared to the sensor device with only air holes (e.g. Figure 32 In the sensing device shown in FIG. 2 , by covering the air holes 2515 with a second flexible film 2580, the equivalent stiffness of the gas can be increased, shifting the resonance peak of the vibration pickup structure 2521 and / or the additional resonant system toward higher frequencies. In some embodiments, the second flexible film 2580 can be the same as or different from the first flexible film 2555.

[0275] Figure 35A is a frequency response curve of an exemplary sensor device including a gas cavity according to some embodiments of the present application. Figure 35A As shown, curve 3510 represents a sensing device provided with air holes 2515 (e.g., Figure 32 Curve 3520 represents a frequency response curve of a sensor device provided with a gas cavity 2504 (e.g., Figure 33 The frequency response curve of the sensor device shown in Figure 1 is shown in Figure 2. Figure 35AIt can be seen that for the sensing device provided with air holes 2515, the rear cavity 2502 is connected to the external environment, and its frequency response curve 3510 has a natural resonance peak O' related to the structure of its transducer unit itself (such as the piezoelectric film) at a higher frequency, and an additional resonance peak R related to the liquid 2540 at a lower frequency band. By providing gas cavity 2504 (corresponding to curve 3520), the volume of the rear cavity is reduced, thereby increasing the equivalent stiffness of the gas in the rear cavity, thereby shifting the natural resonance peak (not shown) of the sensing device and the additional resonance peak S of the additional resonance system to higher frequencies.

[0276] Figure 35B is a frequency response curve of an exemplary sensor device according to some embodiments of the present application. Figure 35B As shown, curve 3530 represents the sensor device (e.g., Figure 25B Frequency response curve of the sensor device shown).

[0277] contrast Figure 35A and Figure 35B When the edge of the gas cavity 2504 is flush with the shell 2510, relative to the curve 3520, it is equivalent to continuing to reduce the volume of the rear cavity, thereby continuing to increase the equivalent stiffness of the gas, so that the inherent resonance peak of the vibration pickup structure 2521 and the additional resonance peak of the additional resonance system continue to move toward high frequency. For example, the frequency corresponding to the additional resonance peak T is greater than the frequency corresponding to the additional resonance peak S.

[0278] Figure 36 It is a schematic top view of the structure of an exemplary sensing device according to some embodiments of the present application. Figure 37 2 is a schematic diagram of the structure of an exemplary sensor device according to some embodiments of the present application. In some embodiments, the mass of the liquid 2540 affects the relevant values in the additional resonant system (i.e., the spring (Kp')-mass (Ml)-damping (Rp') system), thereby affecting the output of the sensor device 2500 (e.g., the natural frequency of the sensor device 2500, the output sensitivity, etc.) (e.g., Figure 38 or Figure 39 As shown), the parameters of the additional resonant system can be adjusted by adjusting the mass of the liquid 2540, thereby adjusting the output of the transducer unit 2520 to achieve the adjustment of the additional resonant frequency and output sensitivity of the sensing device 2500.

[0279] In some embodiments, the liquid 2540 may not fill the entire front chamber 2501. The liquid 2540 may fill the support structure (e.g., Figure 37 The support structure 2590 in the housing 2510 and / or the support plate (such as Figure 37In some embodiments, the mass of liquid 2540 in the sensing device 2500 can be adjusted by adjusting the ratio of the projected area of liquid 2540 in the vibration direction of the vibration pickup structure 2521 to the projected area of the vibration pickup structure 2521 in the vibration direction. For example, if the projected area of the vibration pickup structure 2521 remains unchanged, when the ratio is small, the inner wall of the housing 2510 is close to the liquid 2540 above the vibration pickup structure 2521, which has a greater constraint on the liquid 2540, and the flow of liquid 2540 is obstructed, resulting in a large effective mass. When the ratio is large, the inner wall of the housing 2510 is far from the liquid 2540 above the vibration pickup structure 2521, which has a lesser constraint on the liquid 2540, and the flow resistance of liquid 2540 is small, resulting in a small effective mass. Therefore, within a certain range of the ratio, as the ratio increases, the effective mass of liquid 2540 decreases. Furthermore, beyond this range, as the ratio increases, the effective mass of liquid 2540 remains essentially unchanged. In the present application, the effective mass of the liquid may refer to the equivalent mass that acts on the vibration pickup structure 2521 along the vibration direction of the vibration pickup structure 2521 and becomes a part of the mass in its spring-mass damping system.

[0280] Just as an example, Figure 36 As shown, Sq represents the projected area of the liquid 2540 in the vibration direction of the vibration pickup structure 2521, that is, the area of the dotted square, and Sm represents the projected area of the vibration pickup structure 2521 in its vibration direction, that is, the area of the dotted circle. The ratio α between the two can be expressed as:

[0281]

[0282] In some embodiments, to ensure that the additional resonance frequency provided by the additional resonance system is within the range of 200 Hz-2000 Hz, the ratio of the projected area Sq of the liquid 2540 in the vibration direction of the vibration pickup structure 2521 to the projected area Sm of the vibration pickup structure 2521 in the vibration direction is within the range of 1-30. Furthermore, to ensure that the additional resonance provided by the additional resonance system is within the range of 200 Hz-1500 Hz, the ratio of the projected area Sq of the liquid 2540 in the vibration direction of the vibration pickup structure 2521 to the projected area Sm of the vibration pickup structure 2521 in the vibration direction can be within the range of 1-20. Furthermore, to ensure that the additional resonance provided by the additional resonance system is within the range of 200 Hz-1000 Hz, the ratio of the projected area Sq of the liquid 2540 in the vibration direction of the vibration pickup structure 2521 to the projected area Sm of the vibration pickup structure 2521 in the vibration direction can be within the range of 1-15.

[0283] In some embodiments, the ratio α may be related to the difficulty of the sensor device's packaging process. For example, when the sensor device is a MEMS sensor device, based on a MEMS sensor device packaging process with a length and width of 2.7 mm × 1.8 mm, when the vibration pickup structure 2521 has a size of 0.9 mm × 0.9 mm, the ratio α may be 6. This allows the transducer unit 2520 (or sensor device 2500) to have a smaller size while simultaneously having higher sensitivity and a larger bandwidth. In some embodiments, based on the limitations of the MEMS sensor device packaging process, the ratio α may be in the range of 1-7.

[0284] In some embodiments, the mass of the liquid 2540 in the sensing device 2500 can be adjusted by adjusting the ratio between the filling size of the liquid 2540 in the cavity (e.g., the front cavity 2501 or the rear cavity 2502) in the vibration direction of the vibration pickup structure 2521 and the size of the transducer unit 2520 in the vibration direction. For example, if the size of the transducer unit 2520 remains unchanged, the larger the ratio, the larger the filling size of the liquid 2540 in the cavity, and the greater the mass of the liquid 2540; conversely, the smaller the ratio, the smaller the filling size of the liquid 2540 in the cavity, and the smaller the mass of the liquid 2540.

[0285] Just as an example, Figure 37 As shown, h1 represents the size of the transducer unit 2520 in the vibration direction, and h2 represents the filling size of the liquid 2540 in the front chamber 2501 in the vibration direction. The ratio γ between the two can be expressed as:

[0286]

[0287] In some embodiments, since increasing the ratio γ increases the height of the entire sensor device, it is necessary to consider both the performance and size of the sensor device while considering the mass of liquid 2540. In some embodiments, the ratio γ is not less than 0.5. For example, the ratio γ can be greater than or equal to 0.5. Furthermore, the ratio γ can be in the range of 1-15. Further, the ratio γ can be in the range of 1-10. Even further, the ratio γ can be in the range of 1-7.5.

[0288] Figure 38 is a frequency response curve of an exemplary sensor device provided with liquid 2540 according to some embodiments of the present application. Figure 38As shown, curve 3810 represents the frequency response curve of the sensor device when the ratio of the projected area Sq of the liquid 2540 in the vibration direction of the vibration pickup structure 2521 to the projected area Sm of the vibration pickup structure 2521 in the vibration direction is equal to 1 (i.e., α = 1). Curve 3820 represents the frequency response curve of the sensor device when the ratio α = 1.2. Curve 3830 represents the frequency response curve of the sensor device when the ratio α = 2. Curve 3840 represents the frequency response curve of the sensor device when the ratio α = 9.

[0289] from Figure 38 It can be seen that for a sensor device equipped with liquid 2540, within a certain range (for example, when the ratio α is no greater than 2), as the value of α increases, the effective mass of liquid 2540 decreases, and the frequency corresponding to the resonance peak of sensor device 2500 (for example, the resonance peak within the dashed circle X) (i.e., the resonant frequency) gradually increases, while the sensitivity of sensor device 2500 remains essentially unchanged. Therefore, by adjusting α, a sensor device with a wider bandwidth and higher sensitivity can be obtained. When the ratio α exceeds a certain range (for example, when α is greater than 2), as the ratio α further increases, the effective mass of liquid 2540 remains essentially unchanged, the resonant frequency of sensor device 2500 remains essentially unchanged, and the electrical signal output by sensor device 2500 also remains essentially consistent.

[0290] In summary, by adjusting the ratio α (eg, the ratio α is in the range of 1-30), the sensing device 2500 can have a wider frequency band (ie, a flat frequency response range) and high sensitivity.

[0291] Figure 39 is a frequency response curve of an exemplary sensor device provided with liquid 2540 according to some embodiments of the present application. Figure 39 As shown, curve 3910 represents the frequency response curve of the sensor device when the ratio of the filling size of liquid 2540 in front cavity 2501 to the size of vibration pickup structure 2521 in the vibration direction is 1.25 (γ = 1.25). Curve 3920 represents the frequency response curve of the sensor device when the ratio γ = 2.5. Curve 3930 represents the frequency response curve of the sensor device when the ratio γ = 3.75.

[0292] from Figure 39 It can be seen that for the sensor device provided with liquid 2540, as the ratio γ increases, the frequency corresponding to the resonance peak of sensor device 2500 (e.g., the resonance peak within the dashed circle Y) (i.e., the resonant frequency) gradually decreases, and the sensitivity of sensor device 2500 gradually increases. Therefore, by adjusting the ratio γ (e.g., the ratio γ is not less than 0.5), sensor device 2500 has a high sensitivity and a suitable size.

[0293] Figure 40 is a schematic diagram of an exemplary structure of an air conduction microphone provided according to some embodiments of the present application.

[0294] The difference between the air conduction microphone 4000 and the bone conduction microphone is that the air conduction microphone 4000 generates an output signal in response to air-conducted sound. In some embodiments, the diaphragm of the air conduction microphone can separate the front and rear cavities, while the front and rear cavities of the bone conduction microphone can be connected or disconnected. Figure 40 As shown, the air conduction microphone 4000 includes a housing 4010, a transducer unit 4020, a processing circuit 4030, and a PCB 4040. Exemplarily, the air conduction microphone 4000 is a piezoelectric microphone. The transducer unit 4020 may include a diaphragm and a piezoelectric transducer (not shown). When an air-conducted sound signal enters the sound inlet 4050 and the back cavity 4002, the diaphragm may vibrate, and the piezoelectric transducer generates an electrical signal in response to the sound pressure on the diaphragm. The electrical signal may be transmitted via a wire to the processing circuit 4030 or to other components via circuits on the PCB 4040.

[0295] Figure 41 is a schematic diagram of a sensing device 4100 provided according to some embodiments of the present application.

[0296] like Figure 41 As shown, the sensing device 4100 is formed by filling the air conduction microphone 4000 with liquid. In some embodiments, the sensing device 4100 is filled with liquid 4080 at the sound inlet 4050. The size of the sound inlet 4050 is relatively small, and the diameter can be in the range of 0.01mm-5mm. For example, the diameter of the sound inlet 4050 is 0.3mm, 0.5mm, 0.75mm, 0.8mm, 0.95mm, 1.1mm, 1.2mm, 1.5mm, 2mm, 3mm, 5mm, etc. When the liquid 4080 is filled to the sound inlet 4050, unexpelled air is trapped between the liquid 4080 and the diaphragm in the back cavity 4002 and the sound inlet 4050, forming bubbles 4003. At this time, liquid 4080 and bubbles 4003 exist in the cavity on one side of the diaphragm of the sensor device 4000 (ie, the rear cavity 4002), while the cavity on the other side of the diaphragm is empty (not filled with liquid).

[0297] Figure 42 1 is a frequency response curve of an air conduction microphone before and after being filled with liquid according to some embodiments of the present application.

[0298] like Figure 42 As shown, frequency response curves 4210-4230 are frequency response curves of an air conduction microphone that is not filled with liquid (e.g., air conduction microphone 4000), a sensor device (e.g., sensor device 4100) filled with a first liquid (e.g., a liquid with a kinematic viscosity of 0.65 cst), and a sensor device filled with a second liquid (e.g., a liquid with a kinematic viscosity of 50 cst).

[0299] Frequency response curves 4210-4230 show that, after the air conduction microphone is partially filled with liquid, it forms a sensor device with a second resonant system 740, significantly improving its overall sensitivity (e.g., 15-50 dBV). When filled with liquids of varying viscosities, for example, a sensor device with a kinematic viscosity of 50 cSt and a sensor device with a kinematic viscosity of 0.65 cSt have sensitivity differences between their resonance peaks (e.g., the first or third resonance peaks) and the pre-resonance flat region of approximately 5-15 dBV and 15-40 dBV, respectively. This comparison demonstrates that filling with a liquid with a higher kinematic viscosity is more effective in reducing the Q factor of the sensor device.

[0300] In some embodiments, the liquid filling the piezoelectric air conduction microphone has a kinematic viscosity ranging from 0.1 to 500 cSt. In some embodiments, the liquid filling the piezoelectric air conduction microphone has a kinematic viscosity ranging from 0.5 to 200 cSt. In some embodiments, the liquid filling the piezoelectric air conduction microphone has a kinematic viscosity ranging from 10 to 200 cSt.

[0301] Figure 43 is a schematic diagram of a sensing device 4300 provided according to some embodiments of the present application.

[0302] like Figure 43 As shown, the sensing device 4300 is an air conduction microphone filled with liquid. Exemplarily, the sensing device 4300 can be a capacitive microphone, and its transducer unit can include a diaphragm 4321 (for example, a vibrating electrode membrane) and a back plate 4325 (for example, a back plate with holes). The diaphragm 4321 and the back plate 4325 are placed in parallel and close to each other, respectively constituting the two poles of the capacitor. The power supply provides voltage to the two poles of the capacitor. When there is an external vibration signal, the diaphragm 4321 can vibrate based on the external vibration signal, while the back plate 4325 is fixed, thereby changing the distance between the two poles of the capacitor, thereby changing the capacitance of the capacitor. When the voltage remains unchanged, the amount of electricity in the capacitor changes, thereby generating an electrical signal. The other structures and components of the sensing device 4300 are the same as or similar to those of the sensing device 4100 and will not be repeated here.

[0303] Similar to sensor device 4100, the sound inlet of sensor device 4300 is filled with liquid 4380. When liquid 4380 fills the sound inlet, unexpelled air exists between liquid 4380 and the diaphragm in the back cavity and the sound inlet, forming bubbles 4303. At this point, both liquid 4380 and bubbles 4303 exist on one side of the diaphragm of sensor device 4300, while the other side of the diaphragm is empty (not filled with liquid).

[0304] Figure 44 1 is a frequency response curve of a sensing device filled with liquids of different kinematic viscosities provided according to some embodiments of the present application.

[0305] Frequency response curves 4410 and 4420 are respectively the frequency response curve of the air conduction microphone not filled with liquid and the frequency response curve of the air conduction microphone filled with liquid (eg, silicone oil with a kinematic viscosity of 0.65 cst) corresponding to the sensing device (eg, sensing device 4300).

[0306] Combining frequency response curves 4410 and 4420, it can be seen that the overall sensitivity of the liquid-filled sensing device 4300 is improved by 10-50 dBV compared to an air conduction microphone without liquid. In some embodiments, the overall sensitivity is improved by 15-40 dBV. In some embodiments, the overall sensitivity is improved by 20-35 dBV.

[0307] In some embodiments, the kinematic viscosity of the filling liquid is within 200 cSt. In some embodiments, the kinematic viscosity of the filling liquid is within 100 cSt. In some embodiments, the kinematic viscosity of the filling liquid is within 80 cSt. In some embodiments, the kinematic viscosity of the filling liquid is within 50 cSt.

[0308] Figure 45 is an exemplary schematic diagram of a sensing device 4500 provided according to some embodiments of the present application.

[0309] The sensing device 4500 is an air conduction microphone filled with liquid. The diameter of its sound inlet and back cavity is in the order of millimeters, and the volume of liquid that can be filled is relatively small. Figure 44 As shown, the optional kinematic viscosity range of the filling liquid is relatively small, for example, within 50 cst. In some embodiments, a tube column can be added outside the sound inlet to obtain a larger cavity (the cavity composed of the back cavity, the sound inlet, and the tube column) for filling the liquid 4520. For example, as Figure 45 As shown, the sensing device 4500 is a capacitive microphone, and a tube column 4511 is provided outside its air inlet. The tube column 4511 is fixedly connected to the PCB 4540. The diameter of the tube column 4511 is greater than or equal to the diameter of the sound inlet. The height of the tube column can be set according to the frequency response of the sensing device 4500 formed after filling with liquid or the kinematic viscosity of the filling liquid. For example, within a certain range (for example, within 2 mm, within 3 mm, etc.), as the height of the tube column increases, the range of the kinematic viscosity of the optional filling liquid expands. The height of the tube column can be any value within the range of 0.1-50 mm. The height of the tube column can be, for example, 0.1 mm, 0.3 mm, 0.5 mm, 0.8 mm, 1 mm, 1.2 mm, 1.5 mm, 2 mm, 2.2 mm, 5 mm, 10 mm, etc., or any other tube column height.

[0310] Figure 46 1 is a frequency response curve of a sensing device filled with liquids of different viscosities according to some embodiments of the present application.

[0311] Frequency response curves 4610-4640 are respectively the frequency response curves of the air conduction microphone of the sensing device (e.g., sensing device 4500) before being filled with liquid and the frequency response curves of the liquid filled with different kinematic viscosities (5 cst, 350 cst, 1000 cst).

[0312] Combined with the frequency response curves 4610-4640, it can be seen that after filling with liquid, the overall sensitivity of the sensor device 4500 is improved by about 10-50dBV. In some embodiments, the overall sensitivity improvement can be 15-40dBV. In some embodiments, the overall sensitivity improvement can be 20-35dBV. The sensitivity improvement of the sensor device 4500 is equivalent to that of a sensor device without adding a column (for example, the sensor device 4300). By adding the column 4511, as the kinematic viscosity of the liquid increases, the sensitivity of the sensor device 4500 gradually decreases within a certain range (for example, 200-6000Hz, 200-5000Hz, 500-3000Hz, etc.). Within a certain liquid viscosity range, the sensitivity improvement of the sensor device 4500 is relatively stable. The kinematic viscosity range of the filling liquid can be greater than Figure 44 In some embodiments, the kinematic viscosity of the filling liquid may be within 500 cSt. In some embodiments, the kinematic viscosity of the filling liquid may be within 350 cSt. In some embodiments, the kinematic viscosity of the filling liquid may be within 100 cSt.

[0313] Figure 47 is a schematic diagram of an exemplary sensing device provided according to some embodiments of the present application.

[0314] In some embodiments, sensing device 4700 may include multiple sensing devices (e.g., sensing devices 1200, 1810, 2500, 4100, 4300). At least some of the sensing devices include the first resonant system 530 or the second resonant system 740. For example, at least some of the sensing devices are liquid-filled sensing devices (e.g., sensing devices 2500, 4100, 4300, 4500). In some embodiments, one or more of the at least partially liquid-filled sensing devices (e.g., sensing devices 2500, 4100, 4300, 4500) contain air bubbles (in this specification, air bubbles may also be referred to as air cavities). In some embodiments, the multiple sensing devices may be of the same type. For example, the multiple sensing devices may all be air conduction microphones, bone conduction microphones, energy harvesters, gyroscopes, etc. In other embodiments, at least one of the multiple sensing devices may be of a different type. For example, the plurality of sensing devices include an air conduction microphone and a bone conduction microphone. Figure 47As shown, the sensing device 4700 includes bone conduction microphones 4710-4750. The bone conduction microphones 4710-4750 are respectively arranged at different positions of the human body (for example, different positions around the ears) to pick up sounds at different positions relative to the human body, and based on the sounds at different positions, determine the acoustic characteristics of the sounds at a specific position (for example, inside the auricle). In some embodiments, the bone conduction microphones 4710-4750 are all liquid-filled sensing devices. Among them, the filling liquid of the bone conduction microphones 4710-4730 may contain bubbles; the bone conduction microphones 4740 and 4750 may be filled with liquid and do not contain bubbles. In some embodiments, the bone conduction microphones 4710-4730 and the bone conduction microphones 4740 and 4750 are respectively used to output signals of different frequencies. According to Figure 11-Figure 39 As can be seen from the description, a sensor device filled with bubbles in the liquid has better low- and medium-frequency response and can be used to output low- and medium-frequency electrical signals. A sensor device filled without bubbles in the liquid can output high-frequency electrical signals. Therefore, bone conduction microphones 4710-4730 can be used to output low- and medium-frequency electrical signals, while bone conduction microphones 4740 and 4750 can be used to output high-frequency electrical signals.

[0315] It should be noted that the above description of sensing device 4700 is merely illustrative and does not limit this specification to the illustrated embodiment. It is understood that those skilled in the art, after understanding the principles of the system, may arbitrarily adjust its structure and components without departing from these principles. Such variations are within the scope of protection of this application.

[0316] In some embodiments, sensing device 4700 may include a first sensing device (e.g., liquid-filled sensing device 1200) including a first resonant system 530 and at least one sensing device comprising only a transducer unit. The first sensing device outputs low- to medium-frequency signals, while the sensing device comprising only a transducer unit outputs high- to medium-frequency signals.

[0317] In some embodiments, sensing device 4700 may include a first sensing device (e.g., sensing device 1200 filled with liquid) including a first resonant system 530 and a second sensing device (e.g., sensing device 2500 filled with liquid and bubbles) including a second resonant system 740. The first sensing device outputs low- to medium-frequency signals, while the second sensing device outputs high- to medium-frequency signals.

[0318] Figure 48 is a schematic diagram of an exemplary gyroscope according to some embodiments of the present application.

[0319] like Figure 48As shown, gyroscope 4800 includes a housing 4810 and a rotor 4820 that vibrates within housing 4810. When gyroscope 4800 is stationary or slightly shaken, rotor 4820 vibrates in a horizontal direction 4830. In some embodiments, the vibration of rotor 4820 in horizontal direction 4830 is driven by electromagnetic force. When gyroscope 4800 rotates, a Coriolis force is generated, driving rotor 4820 to vibrate in a vertical direction 4840. The vibration of rotor 4820 in vertical direction 4840 generates a potential difference in a sensor (not shown) that is proportional to the angular velocity of rotation, thereby converting the rotation into an electrical signal.

[0320] In this embodiment, the gyroscope 4800 further includes a first resonant system 530 or a second resonant system 740. For example, the hollow portion within the housing 4810 of the gyroscope 4800 is filled with a liquid. The liquid may or may not contain bubbles. By adjusting the first resonant system 530 or the second resonant system 740, the output frequency response of the gyroscope can be improved. By adjusting the device parameters of the gyroscope 4800 and its internal components (e.g., the mass and volume of the rotor 4820, the size, mass, and stiffness of the housing 4810, etc.) and / or the mechanical parameters of the first resonant system 530 or the second resonant system 740 (e.g., parameters of the filling liquid or the combination of the liquid and bubbles (e.g., liquid viscosity, the number, volume, and position of the bubbles, etc.)), an ideal frequency response of the gyroscope 4800 can be obtained.

[0321] Figure 49 FIG is a schematic diagram of an exemplary test sensor device sensitivity according to some embodiments of the present application. Figure 49 As shown, when measuring the sensitivity of the sensor device, the sensor device can be fixed on the vibration table with an appropriate fixture, and the audio signal generator can send a vibration signal to the vibration table. The vibration signal is amplified by the measurement amplifier to make the vibration table vibrate. The correction excitation acceleration is 3.16m / s 2 or 1g (ie 9.8m / s 2 ), and measure its open circuit voltage using a voltmeter. The measurement result can be calculated according to formula (7):

[0322]

[0323] Where K represents the sensitivity of the sensor device under test, and its dimension is V·s 2 / m; E represents the open-circuit output voltage of the sensor device under test, with the dimension of V; a represents the excitation acceleration of the sensor device under test, with the dimension of m / s 2 In some embodiments, the sensitivity can be calculated according to formula (8):

[0324]

[0325] The dimension of sensitivity K is dBV.

[0326] The beneficial effects that may be brought about by the embodiments of this specification include but are not limited to: (1) by introducing liquid and air cavity, at least one additional resonant frequency can be provided for the sensing device at medium and low frequencies, thereby improving the sensitivity of the sensing device and making the frequency response curve of the sensing device flatter; (2) by arranging the air cavity between the liquid and the shell, the stability of the sensing device is improved; (3) by arranging a first flexible membrane between the liquid and the air cavity, the stability of the sensing device is further improved; (4) by adjusting the equivalent stiffness of the gas in the cavity not filled with liquid, the resonant frequency of the sensing device is adjusted.

[0327] While the basic concepts have been described above, it will be apparent to those skilled in the art that the detailed disclosure is merely illustrative and does not limit this specification. Although not explicitly stated herein, various modifications, improvements, and revisions to this specification may be made by those skilled in the art. Such modifications, improvements, and revisions are suggested in this specification and remain within the spirit and scope of the exemplary embodiments of this specification.

Claims

1. A sensing device comprising: A housing having an accommodating cavity therein; a transducer unit comprising a vibration pickup structure for picking up vibrations of the housing and generating an electrical signal, wherein the transducer unit divides the housing chamber into a front chamber and a rear chamber located on opposite sides of the vibration pickup structure, wherein at least one of the front chamber and the rear chamber is filled with a liquid, the liquid contacts the vibration pickup structure, and an air cavity exists between the liquid and the housing; The frequency response curve of the sensing device has a first resonance peak and a second resonance peak. The first resonance peak is generated by the transducer unit, and the second resonance peak is generated by the liquid and the air cavity. The first resonance peak and the second resonance peak correspond to different frequencies.

2. The sensing device according to claim 1, wherein A gas-liquid interface is formed between the liquid and the gas cavity.

3. The sensing device according to claim 1, wherein: A first flexible membrane is provided between the liquid and the air cavity.

4. The sensing device according to claim 3, wherein: A mass block is provided on the first flexible membrane.

5. The sensing device according to claim 1, wherein The transducer unit includes a plurality of piezoelectric beams, a gap is formed between two adjacent piezoelectric beams among the plurality of piezoelectric beams, a filling component is provided at the position of the gap, and the stiffness of the filling component is smaller than the stiffness of the plurality of piezoelectric beams.

6. The sensing device according to claim 1, wherein The transducer unit includes a plurality of piezoelectric beams, and a gap between two adjacent piezoelectric beams among the plurality of piezoelectric beams is no greater than 20 μm.

7. The sensing device according to claim 1, wherein: The vibration pickup structure includes a plurality of piezoelectric beams and a vibration membrane, wherein the vibration membrane covers surfaces of the plurality of piezoelectric beams to prevent the liquid from passing through the transducer unit.

8. The sensing device according to claim 1, wherein: The transducer unit includes a capacitive transducer, which includes at least a perforated back plate and a vibrating electrode membrane. The liquid can penetrate between the perforated back plate and the vibrating electrode membrane through the holes on the perforated back plate.

9. The sensing device according to claim 8, wherein: An air space exists between the perforated back plate and the vibrating electrode membrane.

10. The sensing device according to claim 1, wherein The shell further comprises a gas cavity, one of the front cavity and the rear cavity is filled with the liquid, and the gas cavity is communicated with the other cavity of the front cavity and the rear cavity which is not filled with the liquid.

11. The sensing device according to claim 10, wherein: A porous dielectric material or a metamaterial is provided in the gas cavity.

12. The sensing device according to claim 1, wherein One of the front cavity and the rear cavity is filled with the liquid, and an air hole is provided at a position of the shell corresponding to the other cavity of the front cavity and the rear cavity which is not filled with the liquid.

13. The sensing device according to claim 12, wherein: The air hole is covered with a second flexible film.

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