SENSING DEVICES

TECHNICAL FIELD

The present disclosure relates to electronic devices, and in particular to sensing devices.

BACKGROUND

A sensor (e.g., a microphone) receives an external vibration signal, and near the resonant frequency of the sensor, the vibration signal may have a relatively large amplitude due to resonance. Therefore, the response of the sensor to the external vibration may manifest that a resonant peak near the resonant frequency is generated in the frequency response curve, and its sensitivity is relatively high near the resonant frequency. However, for some sensors (e.g., air conduction microphones), their resonant frequencies are relatively high (e.g., exceed 10000 Hz), and when the frequency of an external sound signal is at the non-resonant frequency of a sensor, the sensitivity of the sensor is low. The sensitive region of the user to the sound is in a relatively low frequency range relative to the sensor. At this time, the frequency in the relatively low frequency range is much less than the resonant frequency of the sensor. Therefore, for the sound in the sensitive frequency range of the human ear, the sound signal picked up by the sensor is relatively small and the sensitivity is too low.

Therefore, it is desirable to provide a sensing device that can adjust the sensitivity of the device in a wide frequency range, and has stable output gain and high reliability against impact.

SUMMARY

The embodiments of the present disclosure provide a sensing device. The sensing device may include a sensor configured to convert a sound signal into an electrical signal, the sensor having a first resonant frequency. The sensing device may further include a resonant system including a vibration pickup unit configured to generate a vibration in response to a vibration of a housing of the sensing device, the vibration pickup unit including at least an elastic diaphragm and a mass block, the elastic diaphragm being connected to the housing of the sensing device through a peripheral side of the elastic diaphragm, and the mass block being at least made of a polymer material. A first acoustic cavity may be formed between the elastic diaphragm and the sensor, when the housing of the sensing device generates the vibration in response to an external sound signal, the elastic diaphragm and the mass block may generate a vibration in response to the vibration of the housing of the sensing device, the elastic diaphragm may cause a sound pressure change of the first acoustic cavity during a vibration process, and the sensor may convert the external sound signal into an electrical signal based on the sound pressure change of the first acoustic cavity. The resonant system may provide at least one second resonant frequency for the sensing device, and the second resonant frequency may be lower than the first resonant frequency.

In some embodiments, the elastic diaphragm may be a film structure at least made of a polymer material.

In some embodiments, the elastic diaphragm and the mass block may be made of a same material.

In some embodiments, a Young's modulus of the elastic diaphragm may be within a range of 1 MPa-10 GPa.

In some embodiments, a tensile strength of the elastic diaphragm may be within a range of 0.5 MPa-100 MPa.

In some embodiments, an elongation of the elastic diaphragm may be within a range of 10%-600%.

In some embodiments, a hardness shore A of the elastic diaphragm may be less than 200.

In some embodiments, the elastic diaphragm may be a multi-layer composite film structure.

In some embodiments, stiffnesses of at least two layers of the multi-layer composite film structure may be different.

In some embodiments, an area where the mass block is in contact with the elastic diaphragm is less than a projection area of the mass block on the elastic diaphragm.

In some embodiments, the mass block may include a plurality of sub-mass blocks separated from each other, and the plurality of sub-mass blocks may be distributed in different regions of the elastic diaphragm.

In some embodiments, the elastic diaphragm may at least divide a cavity inside the housing into a first acoustic cavity and the second acoustic cavity, the elastic diaphragm may include at least one first hole, and the at least one first hole enables fluid communication between the first acoustic cavity and the at least one second acoustic cavity.

In some embodiments, the at least one first hole may be located in a region on the elastic diaphragm not covered by the mass block.

In some embodiments, the mass block may include at least one second hole, and the at least one second hole may be in fluid communication with the at least one first hole.

In some embodiments, a diameter of the at least one first hole or the at least one second hole may be within a range of 0.01 μm-40 μm.

In some embodiments, the elastic diaphragm may further include at least one elastic layer, and the elastic layer may be located in a region on the elastic diaphragm not covered by the mass block.

In some embodiments, a thickness of the at least one elastic layer may be within a range of 0.1 μm-100 μm.

In some embodiments, a filler with fluidity may be arranged in the at least one second acoustic cavity different from the first acoustic cavity of the sensing device, and a kinematic viscosity of the filler may be within 20000 cst.

In some embodiments, a sensitivity difference between a trough between a first resonant peak corresponding to the first resonant frequency and a second resonant peak corresponding to the second resonant frequency and a peak value of a higher resonant peak of the first resonant peak and the second resonant peak may not be greater than 30 dBV.

In some embodiments, a difference between a minimum sensitivity within a frequency range below the second resonant frequency and a sensitivity of a peak value of a resonant peak corresponding to the second resonant frequency may not be greater than 30 dBV.

In some embodiments, a frequency difference Δf₁between the first resonant frequency and the second resonant frequency may be within a range of 200-15000 Hz.

In some embodiments, a ratio of the frequency difference Δf₁to the first resonant frequency may be within a range of 0.03-8.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is further illustrated in terms of exemplary embodiments. These exemplary embodiments are described in detail with reference to the drawings. These embodiments are non-limiting exemplary embodiments, in which like reference numerals represent similar structures, wherein:

FIG. 1A is a schematic diagram illustrating an exemplary sensor according to some embodiments of the present disclosure;

FIG. 1B is a structural diagram illustrating an exemplary microphone according to some embodiments of the present disclosure;

FIG. 1C is a schematic structural diagram illustrating an exemplary sensing element of a bone conduction microphone according to some embodiments of the present disclosure;

FIG. 2A is a mechanical equivalent diagram of an exemplary sensing device according to some embodiments of the present disclosure;

FIG. 2B is a schematic diagram illustrating a sensing device filled with liquid according to some embodiments of the present disclosure;

FIG. 3 is a schematic diagram illustrating an equivalent vibration model of a resonant system according to some embodiments of the present disclosure

FIG. 4 is a schematic diagram illustrating a normalized displacement resonance curve of a vibration pickup unit with different parameters according to some embodiments of the present disclosure;

FIG. 5A is an exemplary frequency response curve diagram of a sensing device 200 according to some embodiments of the present disclosure;

FIG. 5B is an exemplary frequency response curve diagram of another sensing device according to some embodiments of the present disclosure;

FIG. 6 is a schematic structural diagram illustrating a sensing device according to some embodiments of the present disclosure;

FIG. 7 is a schematic structural diagram illustrating a sensing device of which an elastic diaphragm is a multi-layer composite film structure according to some embodiments of the present disclosure;

FIG. 8 is a schematic structural diagram illustrating a sensing device according to some embodiments of the present disclosure;

FIG. 9 is a cross-sectional view illustrating a sensing device with a ring-shaped mass block according to some embodiments of the present disclosure;

FIG. 10 is a cross-sectional view illustrating a sensing device of which a mass block is a rectangular cylinder according to some embodiments of the present disclosure;

FIG. 11 is a schematic cross-sectional view illustrating a sensing device according to some embodiments of the present disclosure;

FIG. 12 is a schematic cross-sectional view illustrating a sensing device according to some embodiments of the present disclosure;

FIG. 13 is a schematic cross-sectional view illustrating a sensing device according to some embodiments of the present disclosure;

FIG. 14 is a schematic structural diagram illustrating a sensing device according to some embodiments of the present disclosure;

FIG. 15 is a schematic structural diagram illustrating a sensing device of which an elastic diaphragm includes a first hole according to some embodiments of the present disclosure;

FIG. 16 is a schematic cross-sectional view illustrating a sensing device shown in FIG. 15;

FIG. 17 is a schematic cross-sectional view illustrating a sensing device according to some embodiments of the present disclosure; and

FIG. 18 is a schematic structural diagram illustrating a sensing device including a plurality of resonant systems according to some embodiments of the present disclosure.

DETAILED DESCRIPTION

In order to more clearly illustrate the technical solutions related to the embodiments of the present disclosure, a brief introduction of the drawings referred to the description of the embodiments is provided below. Obviously, the drawings described below are only some examples or embodiments of the present disclosure. Those having ordinary skills in the art, without further creative efforts, may apply the present disclosure to other similar scenarios according to these drawings. Unless obviously obtained from the context or the context illustrates otherwise, the same numeral in the drawings refers to the same structure or operation.

It should be understood that “system,” “device,” “unit,” and/or “module” as used herein is a method for distinguishing different components, elements, parts, portions, or assemblies of different levels. However, the words may be replaced by other expressions if other words can achieve the same purpose.

As indicated in the disclosure and claims, the terms “a,” “an,” “an” and/or “the” are not specific to the singular form and may include the plural form unless the context clearly indicates an exception. Generally speaking, the terms “comprising” and “including” only suggest the inclusion of clearly identified steps and elements, and these steps and elements do not constitute an exclusive list, and the method or device may also contain other steps or elements.

The embodiments of the present disclosure provide a sensing device. In some embodiments, the sensing device may include a sensor and a resonant system coupled to the sensor. The sensor may be configured to convert an external signal (e.g., a sound signal, a vibration signal, and a pressure signal) into a target signal (e.g., an electrical signal). The sensor may have a first resonant frequency that is related to the properties (e.g., a shape, a material, a structure, etc.) of the sensor. The resonant system may provide at least one second resonant frequency to the sensing device, wherein the second resonant frequency may be lower than the first resonant frequency. In some embodiments, the sensor may be connected to a vibration pickup unit. The vibration pickup unit may include at least an elastic diaphragm and a mass block. The vibration pickup unit may affect a response of the sensor to the external signal to form the resonant system. In other embodiments, the sensor may be encapsulated in a cavity (e.g., a cavity enclosed by a housing of the sensing device) containing liquid. The liquid and gas (if any) retained in the cavity may affect the response of the sensor to the external signal and form the resonant system.

In some embodiments, by adjusting the properties of the sensor and/or the resonant system, for example, adjusting the viscosity and material of the liquid forming the resonant system or adjusting the structure and material of the vibration pickup unit, a relationship between the second resonant frequency and the first resonant frequency may be adjusted, so that the second resonant frequency may be lower than the first resonant frequency, thereby improving the sensitivity of the sensing device in a relatively low frequency range. In some embodiments, in order to improve the sensitivity of the sensing device in different frequency ranges, the difference between the second resonant frequency and the first resonant frequency may be within a range of 200 Hz-15000 Hz by adjusting the properties of the sensor and/or the resonant system, so that the sensitivity of the sensing device may be significantly improved compared with the sensitivity of the sensor in a required frequency range.

In the embodiments of the present disclosure, in the sensing device in which a resonant system is added on the basis of the sensor, the resonant system provides the second resonant frequency. When the frequency of the external signal is near the second resonant frequency, the sensing device may also have a relatively high sensitivity, which solves the problem that the sensing structure (e.g., an air conduction microphone) itself has a relatively high first resonant frequency, and it only has high sensitivity at the first resonant frequency and low sensitivity in other frequency ranges (e.g., a mid-to-low frequency range), so that the sensing device may have a relatively high sensitivity in a specific frequency range (e.g., near the second resonant frequency) relative to the sensing structure, so as to achieve the purpose of stabilizing the output gain.

In some embodiments, the resonant system may include a vibration pickup unit configured to vibrate in response to a vibration of the housing of the sensing device. The vibration pickup unit may at least include an elastic diaphragm and a mass block. The elastic diaphragm may be connected to the housing of the sensing device through a peripheral side of the elastic diaphragm. In some embodiments, the mass block may be at least made of a polymer material. Elastic properties of the mass block made of the polymer material may absorb an external impact load, thereby effectively reducing a stress concentration at a connection position between the elastic diaphragm and the housing of the sensor, and reducing the possibility of damage to the sensing device due to the external impact. In some embodiments, the mass block and the elastic diaphragm may be made of the same polymer material. Here, when mechanical parameters of the mass block made of the polymer material are the same as or similar to mechanical parameters (e.g., Young's modulus, stiffness, etc.) of the elastic diaphragm, the frequency response of the mass block to a vibration signal and the frequency response of the elastic diaphragm to the vibration signal is similar, thereby further weakening the stress concentration at the connection position between the elastic diaphragm and the housing during the vibration process.

The sensing device and one or more components (e.g., the sensor, the resonant system) of the sensing device in the embodiments of the present disclosure may be described in detail below with reference to the accompanying drawings.

FIG. 1A is a schematic diagram illustrating an exemplary sensor according to some embodiments of the present disclosure. A sensor 100 may be configured to convert a sound signal into an electrical signal, and have a first resonant frequency. Specifically, the sensor 100 may generate a mechanical vibration signal based on the sound signal, and the mechanical vibration signal may be further converted into an electrical signal through a transducer component (e.g., a sensing element 120) of the sensor 100. In some embodiments, the sensor 100 may further generate deformation and/or displacement based on an external signal other than the sound signal, such as a mechanical signal (e.g., pressure, mechanical vibration), an electrical signal, an optical signal, a thermal signal, etc. The deformation and/or displacement may be further converted into a target signal by the transducer component of the sensor 100. In some embodiments, the target signal may include, but is not limited to, one or more of an electrical signal, a mechanical signal (e.g., mechanical vibration), a sound signal (e.g., sound waves), an optical signal, a thermal signal, etc. In some embodiments, the sensor 100 may be a microphone (e.g., an air conduction microphone or a bone conduction microphone), an accelerometer, a pressure sensor, a hydrophone, an energy collector, a gyroscope, or the like. The air conduction microphone refers to a microphone in which sound waves are conducted through the air. The bone conduction microphone refers to a microphone in which sound waves are conducted in a solid (e.g., a bone) in the form of mechanical vibrations. In some embodiments, the sensor 100 may also be a microphone combined with bone conduction and air conduction. The descriptions regarding the microphone combined with bone conduction and air conduction may be found in FIG. 6 and the descriptions thereof in the present disclosure.

In some embodiments, the sensor 100 may include a housing 110 and a sensing element 120, wherein the sensing element 120 may be accommodated in the housing 110. The housing 110 may be a regular or irregular three-dimensional structure with a cavity (i.e., a hollow part) inside. For example, the housing 110 may be a hollow frame structure, including, but is not limited to, regular shapes such as a rectangular frame, a circular frame, or a regular polygonal frame, and any irregular shapes. In some embodiments, the sensing element 120 may be located in the cavity of the housing 110 or at least partially suspended in the cavity of the housing 110. The sensing element 120 may be configured to convert an external signal into a target signal. Taking a bone conduction microphone (also referred to as a vibration sensor) as an example, the external signal may be a mechanical vibration signal. In some embodiments, the sensing element 120 may include a vibration unit and a transducer unit. The vibration unit may have a certain elasticity. For example, the vibration unit may be a vibration rod (e.g., a cantilever beam), a diaphragm, a vibration block, or the like. The vibration unit may generate deformation and/or displacement in response to the mechanical vibration signal. The transducer unit may convert the deformation and/or displacement into the target signal (e.g., an electrical signal). The transducer unit may include a piezoelectric transducer, a capacitive transducer, or the like.

FIG. 1B is a structural diagram illustrating an exemplary microphone according to some embodiments of the present disclosure.

As shown in FIG. 1B, a microphone 140 may include a printed circuit board (PCB) 141, a housing 142, a sensing element 143, and a processor 144. In some embodiments, the PCB 141 may be one or more of a phenolic PCB paper substrate, a composite PCB substrate, a glass fiber PCB substrate, a metal PCB substrate, a laminated multi-layer PCB substrate, or the like. In some embodiments, the PCB 141 may be an FR-4 grade glass fiber PCB substrate made of epoxy glass fiber cloth. Circuits and other components of the microphone 140 may be arranged on the PCB 141 (e.g., by laser etching, chemical etching, etc.). In some embodiments, the PCB 141 may also be a flexible printed circuit board (FPC). In some embodiments, the sensing element 143 and the processor 144 may be fixedly connected to the PCB 141 through a sensing element fixing adhesive 145 and a processor fixing adhesive 146 respectively. In some embodiments, the sensing element fixing adhesive 145 and/or the processor fixing adhesive 146 may be a conductive adhesive (e.g., a conductive silver adhesive, a copper powder conductive adhesive, a nickel carbon conductive adhesive, a silver copper conductive adhesive, etc.). In some embodiments, the conductive adhesive may be one or more of a conductive glue, a conductive adhesive film, a conductive rubber ring, a conductive adhesive tape, or the like. The sensing element 143 and/or the processor 144 may be respectively electrically connected to the other components through the circuits arranged on the PCB 141. The sensing element 143 and the processor 144 may be directly connected through a lead 147 (e.g., a gold wire, a copper wire, an aluminum wire, etc.).

The housing 142 may be a regular or irregular three-dimensional structure with a cavity (i.e., a hollow part) inside. For example, the housing 142 is a hollow frame structure, including, but is not limited to, a regular shape such as a rectangular frame, a circular frame, and a regular polygonal frame, or any irregular shape. The housing 142 may cover the the PCB 141 and seal the sensing element 143, the processor 144, and the PCB 141 and the circuits and the other components arranged thereon. The housing 142 may be made of metal (e.g., stainless steel, copper, etc.), plastic (e.g., polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), or acrylonitrile-butadiene ethylene-styrene copolymer (ABS), etc.), composite materials (e.g., metal matrix composites or non-metal matrix composites), etc. For example, in some embodiments, the material of the housing 142 may be brass.

The sensing element 143 may convert an external vibration signal into an electrical signal. Taking a bone conduction microphone as an example, the sensing element 143 may include a base structure, a laminated structure, and at least one damping structure layer. In some embodiments, at least a portion of the laminated structure may be physically connected to the base structure. The “connection” mentioned in the present disclosure may be understood as the connection between different parts on the same structure, or fixedly connecting each independent part or structure through welding, riveting, clamping, bolting, gluing, etc., after preparing different parts or structures separately, or depositing a first part or structure onto a second part or structure by physical deposition (e.g. physical vapor deposition) or chemical deposition (e.g. chemical vapor deposition) during the preparation process. In some embodiments, at least a portion of the laminated structure may be fixed to an upper surface or a lower surface of the base structure, and at least a portion of the laminated structure may also be fixed to a sidewall of the base structure. For example, the laminated structure may be a cantilever beam. The cantilever beam may be a plate-shaped structure, one end of the cantilever beam may be connected to the upper surface or the lower surface of the base structure, or the side wall where a cavity of the base structure is located, and the other end of the cantilever beam may not be connected to or contacted with the base structure, so that the other end of the cantilever beam may be suspended in the cavity of the base structure. As another example, the bone conduction microphone may include a diaphragm layer (also referred to as a suspension film structure). The suspension film structure may be fixedly connected to the base structure, and the laminated structure may be arranged on an upper surface or a lower surface of the suspension film structure. As another example, the laminated structure may include a mass element and one or more support arms. The mass element may be fixedly connected to the base structure through the one or more support arms. One end of the support arm(s) may be connected to the base structure, and the other end of the support arm(s) may be connected to the mass element, so that a portion of the mass element and the support arm(s) may be suspended in the cavity of the base structure. It should be known that being “located in the cavity” or “suspended in the cavity” in the present disclosure may mean being suspended in, below, or above the cavity.

In some embodiments, the laminated structure may include a vibration unit and an acoustic transducer unit. The vibration unit refers to a portion of the laminated structure that easily deforms by an external force. The vibration unit may be used to transmit deformation caused by the external force to the acoustic transducer unit. The acoustic transducer unit refers to a portion of the laminated structure that converts the deformation of the vibration unit into an electrical signal. Specifically, the base structure may generate a vibration based on an external vibration signal, and the vibration unit may deform in response to the vibration of the base structure; and the acoustic transducer unit may generate the electrical signal based on the deformation of the vibration unit. It should be known that the description of the vibration unit and the acoustic transducer unit here is only for the purpose of conveniently introducing the working principle of the laminated structure, and does not limit the actual composition and structure of the laminated structure. In fact, the vibration unit may not be necessary, and its function may be completely implemented by the acoustic transducer unit. For example, after certain changes are made to the structure of the acoustic transducer unit, the acoustic transducer unit may generate an electrical signal by directly responding to the vibration of the base structure.

In some embodiments, the vibration unit and the acoustic transducer unit may overlap to form the laminated structure. The acoustic transducer unit may be located on an upper layer of the vibration unit, or the acoustic transducer unit may be located on a lower layer of the vibration unit.

In some embodiments, the acoustic transducer unit may include at least two electrode layers, e.g., a first electrode layer and a second electrode layer) and a piezoelectric layer. The piezoelectric layer may be located between the first electrode layer and the second electrode layer. The piezoelectric layer refers to a structure that can generate a voltage on two side surfaces of the piezoelectric layer when an external force is applied. In some embodiments, the piezoelectric layer may generate the voltage under the deformation stress of the vibration unit. The first electrode layer and the second electrode layer may collect the voltage (the electrical signal).

The damping structure layer refers to a structure having damping properties. In some embodiments, the damping structure layer may be a film-shaped structure or a plate-shaped structure. Further, 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 the lower surface of the laminated structure or between a plurality of layers of the laminated structure. For example, if the laminated structure is a cantilever beam, the damping structure layer may be located on an upper surface and/or a lower surface of the cantilever beam. As another example, if the laminated structure includes one or more support arms and a mass element, and when the mass element protrudes downward relative to the one or more support arms, the damping structure layer may be located on the lower surface of the mass element and/or the upper surface of the one or more support arms. In some embodiments, for the macro-sized laminated structure and the base structure, the damping structure layer may be directly bonded to the base structure or the laminated structure. In some embodiments, for a micro-electromechanical systems (MEMS) device, the damping structure layer may be connected to the laminated structure and the base structure by using a semiconductor process, such as evaporation, spin coating, micro-assembly, or the like. In some embodiments, a shape of the damping structure layer may be a regular or irregular shape such as a circle, an ellipse, a triangle, a quadrangle, a hexagon, or an octagon. In some embodiments, an output effect of the electrical signal of the bone conduction microphone may be improved by selecting a material, a size, a thickness, etc., of the damping structure layer.

In some embodiments, the base structure and the laminated structure may be located in the housing 142 of the bone conduction microphone. The base structure may be fixedly connected to an inner wall of the housing 142, and the laminated structure may be carried on the base structure. The descriptions regarding the specific structure of the laminated structure may be found elsewhere in the present disclosure (e.g., FIG. 1C and descriptions thereof).

When the housing 142 of the bone conduction microphone vibrates by an external force (e.g., the vibration of the face when the human body speaks may drive the housing 142 to vibrate), the vibration of the housing 142 may drive the base structure to vibrate. As the laminated structure and the housing structure (or the base structure) have different properties, the laminated structure, and the housing 142 may not maintain a completely consistent movement, thereby generating relative movement, and then causing the deformation of the vibration unit of the laminated structure. Further, when the vibration unit deforms, the piezoelectric layer of the acoustic transducer unit may generate a potential difference (voltage) by the deformation stress of the vibration unit. The at least two electrode layers (e.g., the first electrode layer and the second electrode layer) respectively located on the upper surface and the lower surface of the piezoelectric layer of the acoustic transducer unit may pick up this potential difference to convert the external vibration signal into an electrical signal.

Damping of the damping structure layer may be different under different stress (deformation) states. For example, relatively large damping may be presented at high stress or large amplitude. Therefore, by adding the damping structure layer, a quality factor (Q value) of a resonant region may be reduced while ensuring not reducing the sensitivity of the bone conduction microphone in a non-resonant region based on the characteristics that the laminated structure has a small amplitude in the non-resonant region and large amplitude in the resonant region, so that the frequency response of bone conduction microphone may be relatively flat across the entire frequency range. The bone conduction microphone may be applied to an earphone (e.g., a bone conduction earphone or an air conduction earphone), glasses, a virtual reality (VR) device, a helmet, etc. The bone conduction microphone may be placed on the human head (e.g., face), on the neck, near the ears, on the top of the head, or in other positions. The bone conduction microphone may pick up a vibration signal of a bone when a person speaks, and convert the vibration signal into an electrical signal to implement sound collection. It should be noted that the base structure may not be limited to an independent structure relative to the housing 142 of the bone conduction microphone. In some embodiments, the base structure may also be a portion of the housing 142 of the bone conduction microphone.

Taking an air conduction microphone as an example, the air conduction microphone may include a moving-coil microphone, a condenser microphone, or the like. The sensing element 143 of the moving-coil microphone may include a diaphragm, a coil, and a magnet. The magnet may be configured to generate a magnetic field. When there is an air conduction sound, the diaphragm may generate vibration, and the vibration of the diaphragm may drive the coil to move in the magnetic field to cut the magnetic induction lines, thereby generating an electrical signal to implement sound collection. The sensing element 143 of the condenser microphone may include a diaphragm, a back board, and a power supply. The diaphragm and the back board may be placed in parallel and close to each other, forming two poles of a capacitor respectively. The power supply may supply voltage to the two poles of the capacitor. When there is an air conduction sound, the diaphragm may generate vibration, thereby changing a distance between the two poles of the capacitor, and changing the capacitance of the capacitor. When the voltage remains constant, the electric quantity in the capacitor may change, thereby generating an electrical signal and implementing sound collection.

The processor 144 may obtain the electrical signal from the sensing 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, or the like. The processor 144 may include a microcontroller, a microprocessor, an application-specific integrated circuit (ASIC), an application-specific instruction set processor (ASIP), a central processing unit (CPU), a physical processing unit (PPU), a digital signal processor (DSP)), a field programmable gate array (FPGA), an advanced reduced instruction set computer (ARM), a programmable logic device (PLD), or other types of processing circuits or processors.

FIG. 1C is a schematic structural diagram illustrating an exemplary sensing element of a bone conduction microphone according to some embodiments of the present disclosure.

In this embodiment, the sensing element 143 may include a matrix 181 and a cantilever beam 182. A lower part of the matrix 181 may be fixedly connected to the PCB 141. One end of the cantilever beam 182 may be fixed to the matrix 181, and the other end of the cantilever beam 182 may be suspended in the cavity of the housing 142. The cantilever beam 182 may include a laminated structure. The laminated structure may include a vibration unit and an acoustic transducer unit. The vibration unit may include at least one elastic layer. The acoustic transducer 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 may be located on a surface of the first electrode layer or the second electrode layer. The elastic layer may deform during the vibration process. The piezoelectric layer may generate the electrical signal based on the deformation of the elastic layer. The first electrode layer and the second electrode layer may collect the electrical signal. Merely by way of example, 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-shaped structure made of semiconductor material. In some embodiments, the semiconductor material may include silicon dioxide, silicon nitride, gallium nitride, zinc oxide, silicon carbide, or the like. In some embodiments, the material of the first elastic layer and the material of the second elastic layer may be the same or different.

In some embodiments, the piezoelectric layer may be a piezoelectric polymer film obtained by a semiconductor deposition process (e.g., magnetron sputtering, and MOCVD). In some embodiments, the material of the piezoelectric layer may include a piezoelectric crystal material and a piezoelectric ceramic material. The piezoelectric crystal refers to a piezoelectric monocrystal. In some embodiments, the piezoelectric crystal material may include crystal, sphalerite, boborite, tourmaline, zincite, GaAs, barium titanate and a derivative structure crystal thereof, KH2PO4, NaKC4H4O6·4H2O (Rochelle salt), or the like, or any combination thereof. The piezoelectric ceramic material refers to a piezoelectric polycrystal formed by a random collection of fine grains obtained by solid-state reaction and sintering between powder granules 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 (AlN), zinc oxide (ZnO), or the like, or any combination thereof. In some embodiments, the piezoelectric layer material may also be a piezoelectric polymer material, e.g., polyvinylidene fluoride (PVDF), or the like. In some embodiments, the first electrode layer and the second electrode layer may be structures made of conductive materials. Exemplary conductive materials may include metals, alloy materials, metal oxide materials, graphene, or the like, or any combination thereof. In some embodiments, the metals and the alloy materials may include nickel, iron, lead, platinum, titanium, copper, molybdenum, zinc, or any combination thereof. In some embodiments, the alloy materials may include a copper-zinc alloy, a copper-tin alloy, a copper-nickel-silicon alloy, a copper-chromium alloy, a copper-silver alloy, or the like, or any combination thereof. In some embodiments, the metal oxide materials may include RuO₂, MnO₂, PbO₂, NiO, or the like, or any combination thereof.

In some embodiments, the cantilever beam 182 may also include other structure layers, e.g., a seed layer, a damping layer, etc., which are not specifically limited in the present disclosure. Merely by way of example, as shown in FIG. 1C, the cantilever beam 182 may be composed of an elastic layer 1431, an upper electrode 1432, a functional layer 1433, a bottom electrode 1434, and a seed layer 1435 from top to bottom. In some embodiments, the material of the seed layer 1435 and the material of the functional layer 1433 may be consistent. In some embodiments, the matrix 181 used to support the cantilever beam 182 may be made of Si and other semiconductor materials.

FIG. 2A is a mechanical equivalent diagram of an exemplary sensing device according to some embodiments of the present disclosure. As shown in FIG. 2A, a sensing device 200 may include the sensor 100 and a resonant system 210. In some embodiments, the sensing device 200 may be regarded as additionally arranging the resonant system 210 on the basis of the sensor 100. For example, in this embodiment, the resonant system 210 may be a spring (Km₄)-mass (Mm₄)-damping (Rm₄) system. Taking the sensor 100 in FIG. 1A as an example, the resonant system 210 may be coupled between the housing 110 of the sensor 100 and the sensing element 120. Due to the effect of the resonant system 210, when the housing 110 receives an external vibration signal (e.g., a sound signal), the external vibration signal may be transmitted to the sensing element 120 through a housing region connecting to the sensor element 120 and a housing region connecting to the resonant system 210, respectively. Therefore, the mechanical response of the sensing device 200 may change compared with the sensor 100. Accordingly, the electrical, acoustic, and/or thermal response of the sensing device 200 may change compared with the sensor 100.

In some embodiments, the resonant system 210 may be formed by a composite structure of an elastic structure (e.g., an elastic rod, an elastic sheet, an elastic diaphragm, an elastic block, an elastic mesh bracket, an elastic connection structure (e.g., a light spring)) connected to the sensing element 120 and having a certain mass and a mass element (e.g., a mass block), etc. In some embodiments, the resonant system 210 may include at least one elastic rod. Two ends of the at least one elastic rod may be respectively fixedly connected to the housing 110 and the sensing element 120. In some embodiments, the resonant system 210 may be a combination of at least one set of elastic connection structure (e.g., a light spring, a light elastic rod, an elastic diaphragm, etc.) and a mass element. For example, the elastic connection structure may include an elastic diaphragm. Both ends of the elastic diaphragm may be connected to the housing 110. The mass block may be fixedly connected to or placed on the elastic diaphragm. More descriptions regarding the resonant system 210 formed by the combination of the elastic diaphragm and the mass block may be found elsewhere in the present disclosure (e.g., FIG. 6 and descriptions thereof). In some embodiments, the resonant system 210 may also be integrally manufactured with the sensing element 120. For example, the resonant system 210 in the form of the elastic rod may be integrated with the sensing element 120 through injection molding or physical growth.

In some embodiments, the resonant system 210 may also be formed by liquid. For example, the liquid may fill the cavity in the housing 110, and the sensing element 120 may be wrapped in the liquid. FIG. 2B is a schematic diagram illustrating a sensing device filled with liquid according to some embodiments of the present disclosure. The liquid may have safety performance (e.g., non-flammable and non-explosive properties) and stable performance (e.g., non-volatile property, no high-temperature deterioration, etc.). For example, the liquid may include oil (e.g., silicone oil, glycerin, castor oil, engine oil, lubricating oil, hydraulic oil (e.g., aviation hydraulic oil), etc.), water (including pure water, aqueous solutions of other inorganic or organic substances, etc. (e.g., brine)), oil-water emulsion, or other liquids that meet the performance requirements, or a combination thereof.

In some embodiments, the sensing device may also include a plurality of resonant systems. For example, each resonant system may be composed of a set of elastic diaphragm and mass block. As another example, each resonant system of the plurality of resonant systems may be formed by different types of liquids, liquids of different densities, kinematic viscosities, etc., respectively. In some embodiments, when the liquid is not completely filled in the cavity of the housing 110, air bubbles may exist in the housing 110, wherein the liquid and the air bubbles may serve as one resonant system. Further descriptions regarding the sensing device including the plurality of resonant systems may be found elsewhere in the present disclosure (e.g., FIG. 18 and descriptions thereof).

In some embodiments, the resonant system of the sensing device in the embodiments of the present disclosure may be equivalent to a vibration model. FIG. 3 is a schematic diagram illustrating an equivalent vibration model of a resonant system according to some embodiments of the present disclosure. As shown in FIG. 3, the resonant system (e.g., the resonant system 210 in FIG. 2A) may be simplified as and equivalent to a mass-spring-damping system. The mass-spring-damping system may be forced to vibrate under an action of an exciting force F, and its vibration law may conform to the law of the mass-spring-damping system. For the resonant system, the elastic diaphragm (e.g., an elastic diaphragm 621 in FIG. 6) in the embodiments of the present disclosure may provide an effect of spring and damping to the resonant system 210. The mass block (e.g., a mass block 622 in FIG. 6) in the embodiments of the present disclosure may provide a mass.

The motion of the resonant system may be described by the following differential equation:

$\begin{matrix} M \frac{d^{2} x}{{dt}^{2}} + R \frac{d x}{dt} + K x = F \cos ω t, & (1) \end{matrix}$

where M denotes the mass of the resonant system, R denotes the damping of the resonant system, K denotes an elastic coefficient of the resonant system, F denotes an amplitude of a driving force, x denotes the displacement of the resonant system, and co denotes a circular frequency of an external force. The following is obtained by solving the above equation for the steady-state displacement:

x=x
_acos(ωt−0), (2)

where,

$x_{a} = \frac{F}{ω ❘ Z ❘} = \frac{F}{ω \sqrt{R^{2} + {(ω M - K ω^{- 1})}^{2}}} .$

In FIG. 1A, FIG. 2A, and FIG. 3, when the sensing device 200 actually works, x corresponds to the deformation of a vibration-electrical signal conversion part of the sensing element 120 of the sensor 100, and the magnitude of x finally corresponds to the magnitude of an electrical signal output. A displacement amplitude ratio (normalized) is:

$\begin{matrix} x_{a} = \frac{F}{ω ❘ Z ❘} = \frac{F}{ω \sqrt{R^{2} + {(ω M - K ω^{- 1})}^{2}}}, & (3) \end{matrix}$

where

$Q_{m} = \frac{ω_{0} M}{R},$

which denotes a mechanical quality factor; and

$x_{a 0} = \frac{F}{K}$

denotes a static displacement amplitude (or a displacement amplitude when ω=0).

Normalized displacement resonance curves of the sensing device 200 formed by resonant systems with different parameters (the elastic coefficient, the mass, and the damping) may be shown in FIG. 4. A horizontal axis corresponds to a ratio

$\frac{ω}{ω_{0}}$

of the frequency of the external force (or vibration) to the resonant frequency of the system, and a vertical axis corresponds to the A value of equation (3). It can be seen that different sensing devices 200 may have different resonant systems and different mechanical quality factor Qm values, which correspond to different curves in the figure, and have different displacements A. When the ratio

$\frac{ω}{ω_{0}}$

of the frequency of the external force (or vibration) to the resonant frequency of the system is 1, the system undergoes resonance, and the displacement may change the most at this time. The larger the Q_mvalue of the resonant system, the larger the A value, and the steeper the curve; the smaller the Q_mvalue of the resonant system, the smaller the A value, and the flatter the curve. Therefore, the Q value may be adjusted by adjusting the quality factor Q_mvalue (e.g., changing the structure) of the resonant system.

The principle of the sensor generating the voltage signal may be that the vibration-electrical signal conversion device (e.g., the sensing element 120) and the housing (e.g., the housing 110) of the sensing device may generate relative displacement (e.g., an electret microphone may deform through the diaphragm to change a distance to a substrate to form a voltage signal; a cantilever beam type bone conduction sensor may deform through a cantilever vibration device to generate an inverse piezoelectric effect, thereby forming an electrical signal), and the greater the displacement, the greater the output signal. Obviously, the vibration-electrical signal conversion device of the sensor fully conforms to the displacement resonance curve in FIG. 4.

In some embodiments, the resonant system may also include an elastic support component. The elastic diaphragm and the elastic support component may be jointly used as an equivalent spring, and an overall elastic coefficient K value may be lower, which may amplify the deformation, thereby improving the sensitivity of the sensing device 200. In this embodiment, in terms of the specific vibration form, when the mass block moves up and down under an action of inertia while pulling the elastic diaphragm to bend and deform, it may also pull the elastic support component to deform in longitudinal and transverse directions, thereby amplifying the displacement of the mass block.

Based on the above equation, the resonant frequency (i.e., a second resonant frequency) of the resonant system 210 is:

$\begin{matrix} ω_{0} = \sqrt{\frac{K}{m}}, & (4) \end{matrix}$

where ω₀denotes the resonant frequency of the system.

A relationship between the resonant frequency of the sensing device and the resonant frequency of the resonant system 210 is:

f=ω
₀/(2*pi), (5)

where f denotes the resonant frequency of the sensing device.

In the equations (4) and (5), when

$\frac{K}{m}$

decreases, the resonant frequency of the resonant system decreases. When a resonant frequency is changed, the sensitivity of the signal before the resonant frequency may increase, but after the resonant frequency, the sensitivity of a section of the frequency signal may decrease. When adjusting the sensitivity by adjusting the resonant frequency (e.g., adjusting the second resonant frequency provided by the resonant system 210) of the sensing device 200, it is necessary to consider the frequency range. In some embodiments, the resonant frequency of the sensing device 200 may be within a range of 1500 Hz-6000 Hz. In some embodiments, the resonant frequency of the sensing device 200 may be within a range of 1500 Hz-3000 Hz. In some embodiments, the resonant frequency of the sensing device 200 may be within a range of 2000 Hz-2500 Hz.

In some embodiments, the frequency response curve of the sensing device 200 may include at least two resonant peaks. The at least two resonant peaks may include a first resonant peak and a second resonant peak. The first resonant peak may be a resonant peak corresponding to the sensor 100, and the corresponding resonant frequency may be mainly related to the properties (e.g., the shape, the material, the structure, etc.) of the sensing element 120. The second resonant peak may be a resonant peak generated by an additional system (for the sensing device 200, the additional system may be the resonant system 210) of the sensor 100, and the corresponding resonant frequency may be mainly related to one or more mechanical parameters (e.g., the equivalent spring (Km₄), the mass (Mm₄), the damping (Rm₄), etc., of the resonant system) of the additional system. In order to make the sensing device 200 applicable to different scenarios, the resonant frequency (also referred to as the first resonant frequency) corresponding to the first resonant peak and the resonant frequency (also referred to as the second resonant frequency) corresponding to the second resonant peak may satisfy different relationships. For example, the second resonant frequency may be less than, equal to, or greater than the first resonant frequency. In some embodiments, in order to improve the sensitivity of the sensing device 200 in a relatively low frequency range, the second resonant frequency may be less than the first resonant frequency. For example, a difference between the first resonant frequency and the second resonant frequency may be within a range of 200 Hz-15000 Hz. As another example, the difference between the first resonant frequency and the second resonant frequency may be within a range of 500 Hz-8000 Hz. As another example, the difference between the first resonant frequency and the second resonant frequency may be within a range of 1000 Hz-5000 Hz.

Merely by way of illustration, due to the existence of the second resonant peak corresponding to the resonant system 210, the frequency response curve of the sensing device 200, especially in a mid-to-low frequency range where voice information is relatively rich, may be elevated, making the sensitivity of the sensing device 200 improved compared with the sensor 100. In addition, since the resonant system 210 acts on the sensing element 120, the vibration characteristic of the sensor 100 may change compared with that without the resonant system 210. Specifically, the resonant system 210 may act on the sensing element 120, which may affect the mass, stiffness, and/or damping of the sensor 100, and the effect may be equivalent to making the Q value of the first resonant peak of the sensing device 200 change (e.g., the Q value may decrease) relative to the Q value of the sensor 100 without connection of the first resonant system 210. The frequency response curve, the first resonant peak, and the second resonant peak of the sensing device 200 may be described in more detail below with reference to FIG. 5A and FIG. 5B.

FIG. 5A is an exemplary frequency response curve diagram of a sensing device 200 according to some embodiments of the present disclosure. As shown in FIG. 5A, a frequency response curve 510 indicated by a dotted line represents a frequency response curve of the sensor 100, and a frequency response curve 520 indicated by a solid line represents a frequency response curve of the sensing device 200. The abscissa represents the frequency, the unit is Hertz (Hz), and the ordinate represents the sensitivity, the unit is volt decibel (dBV). The frequency response curve 510 may include a resonant peak 511 corresponding to the resonant frequency of the sensor 100. The frequency response curve 520 may include a first resonant peak 521 and a second resonant peak 522. For the sensing device 200, the frequency corresponding to the first resonant peak 521 may be the first resonant frequency. The second resonant peak 522 may be formed by an action of the resonant system 210, and the frequency corresponding to the second resonant peak 522 may be the second resonant frequency.

It should be noted that the second resonant peak 522 shown in the figure is on the left of the first resonant peak 521, i.e., the frequency corresponding to the second resonant peak 522 may be less than the frequency corresponding to the first resonant peak. In some embodiments, by changing mechanical parameters of the sensor 100 or the resonant system 210, the frequency (i.e., the second resonant frequency) corresponding to the second resonant peak 522 may be greater than the frequency (i.e., the first resonant frequency) corresponding to the first resonant peak 521, i.e., the second resonant peak 522 is on the right of the first resonant peak 521. In some embodiments, when the resonant system 210 includes a vibration pickup unit composed of an elastic diaphragm and a mass block, the second resonant peak 522 may be on the left of the first resonant peak 521, i.e., the second resonant frequency may be lower than the first resonant frequency. For example, in some embodiments, a difference between the second resonant frequency and the first resonant frequency may be within a range of 200 Hz-15000 Hz. As another example, in some embodiments, the difference between the second resonant frequency and the first resonant frequency may be within a range of 1000 Hz-8000 Hz. As another example, in some embodiments, the difference between the second resonant frequency and the first resonant frequency may be within a range of 2000 Hz-6000 Hz. In some embodiments, a position of the second resonant peak 522 may be related to the mechanical parameters of the elastic diaphragm (e.g., an elastic diaphragm 621 in FIG. 6) and/or the mass block (e.g., a mass block 622 in FIG. 6). For example, the greater the mass of the mass block, the smaller the second resonant frequency, and the second resonant peak 522 may shift to a low frequency, or the better the elasticity of the elastic diaphragm, the greater the second resonant frequency, and the second resonant peak 522 may shift to a high frequency. In some embodiments, for the sensing device 200 of which the inside is filled with the liquid as the resonant system, the second resonant peak 522 may be on the left of the first resonant peak 521, and the position may be related to the properties (e.g., the density, the kinematic viscosity, the volume, etc.) of the filled liquid and the properties of the elastic diaphragm. As the density of the liquid decreases or the kinematic viscosity of the liquid increases, the resonant peak may shift to a high frequency.

In some embodiments, the frequency corresponding to the resonant peak 511 may be within a range of 100 Hz-18000 Hz. In some embodiments, the frequency corresponding to the resonant peak 511 may be within a range of 100 Hz-10000 Hz. In some embodiments, the frequency corresponding to the resonant peak 511 may be within a range of 500 Hz-10000 Hz. In some embodiments, the frequency corresponding to the resonant peak 511 may be within a range of 1000 Hz-7000 Hz. In some embodiments, the frequency corresponding to the resonant peak 511 may be within a range of 1500 Hz-5000 Hz. In some embodiments, the frequency corresponding to the resonant peak 511 may be within a range of 2000 Hz-5000 Hz. In some embodiments, the frequency corresponding to the resonant peak 511 may be within a range of 2000 Hz-4000 Hz. In some embodiments, the frequency corresponding to the resonant peak 511 may be within a range of 3000 Hz-4000 Hz.

In some embodiments, the frequency (i.e., the first resonant frequency) corresponding to the first resonant peak 521 and the resonant frequency corresponding to the resonant peak 511 may be the same. For example, when the resonant system includes a vibration pickup unit formed by a combination of an elastic diaphragm and a mass block, the resonant system may have almost no influence on the stiffness, the mass, and the damping of the sensor, and thus the first resonant frequency of the sensor 100 of the sensing device 200 may not change relative to the resonant frequency (i.e., the resonant frequency corresponding to the resonant peak 511) of the sensor 100.

In some embodiments, the frequency corresponding to the first resonant peak 521 may be within a range of 100 Hz-18000 Hz. In some embodiments, the frequency corresponding to the first resonant peak 521 may be within a range of 500 Hz-10000 Hz. In some embodiments, the frequency corresponding to the first resonant peak 521 may be within a range of 1000 Hz-10000 Hz. In some embodiments, the frequency corresponding to the first resonant peak 521 may be within a range of 1500 Hz-7000 Hz. In some embodiments, the frequency corresponding to the first resonant peak 521 may be within a range of 1500 Hz-5000 Hz. In some embodiments, the frequency corresponding to the first resonant peak 521 may be within a range of 2000 Hz-5000 Hz. In some embodiments, the frequency corresponding to the first resonant peak 521 may be within a range of 2000 Hz-4000 Hz. In some embodiments, the frequency corresponding to the first resonant peak 521 may be within a range of 3000 Hz-4000 Hz.

In some embodiments, the resonant frequency (the first resonant frequency) corresponding to the first resonant peak 521 and the resonant frequency corresponding to the resonant peak 511 may be different. For example, for the sensing device 200 in FIG. 2B of which the cavity of the housing 110 is filled with the liquid, the liquid may act as the resonant system 210. Since the liquid is incompressible, the rigidity of the system increases, and the first resonant frequency corresponding to the first resonant peak 521 may increase compared with the resonant frequency corresponding to the resonant peak 511, i.e., the first resonant peak 521 may shift to the right relative to the resonant peak 511.

In some embodiments, the frequency corresponding to the second resonant peak 522 may be within a range of 50 Hz-15000 Hz. In some embodiments, the frequency corresponding to the second resonant peak 522 may be within a range of 50 Hz-10000 Hz. In some embodiments, the frequency corresponding to the second resonant peak 522 may be within a range of 50 Hz-6000 Hz. In some embodiments, the frequency corresponding to the second resonant peak 522 may be within a range of 100 Hz-5000 Hz. In some embodiments, the frequency corresponding to the second resonant peak 522 may be within a range of 500 Hz-5000 Hz. In some embodiments, the frequency corresponding to the second resonant peak 522 may be within a range of 1000 Hz-5000 Hz. In some embodiments, the frequency corresponding to the second resonant peak 522 may be within a range of 1000 Hz-5000 Hz. In some embodiments, the frequency corresponding to the second resonant peak 522 may be within a range of 1000 Hz-2000 Hz. In some embodiments, the frequency corresponding to the second resonant peak 522 may be within a range of 1500 Hz-2000 Hz. In some embodiments, by adjusting one or more mechanical parameters (e.g., a mass of a mass block 622 in FIG. 6, a stiffness of an elastic diaphragm 621, a size of a first acoustic cavity 630, etc.) of the structure, the material, and the resonant system of the sensing device, a frequency range between the two resonant peaks 521 and 522 on the frequency response curve 520 may be relatively flat, thereby improving the output quality of the sensing device 200. In some embodiments, a sensitivity difference between values of a trough between the first resonant peak 521 corresponding to the first resonant frequency and the second resonant peak 522 corresponding to the second resonant frequency and a higher resonant peak of the first resonant peak and the second resonant peak may not be greater than 50 dBV. In some embodiments, the sensitivity difference between values of a trough between the first resonant peak 521 corresponding to the first resonant frequency and the second resonant peak 522 corresponding to the second resonant frequency and a higher resonant peak of the first resonant peak and the second resonant peak may not be greater than 20 dBV. In some embodiments, the sensitivity difference between values of a trough between the first resonant peak 521 corresponding to the first resonant frequency and the second resonant peak 522 corresponding to the second resonant frequency and a higher resonant peak of the first resonant peak and the second resonant peak may not be greater than 15 dBV. In some embodiments, the sensitivity difference between values of a trough between the first resonant peak 521 corresponding to the first resonant frequency and the second resonant peak 522 corresponding to the second resonant frequency and a higher resonant peak of the first resonant peak and the second resonant peak may not be greater than 10 dBV. In some embodiments, the sensitivity difference between values of a trough between the first resonant peak 521 corresponding to the first resonant frequency and the second resonant peak 522 corresponding to the second resonant frequency and a higher resonant peak of the first resonant peak and the second resonant peak may not be greater than 8 dBV. In some embodiments, the sensitivity difference between values of a trough between the first resonant peak 521 corresponding to the first resonant frequency and the second resonant peak 522 corresponding to the second resonant frequency and a higher resonant peak of the first resonant peak and the second resonant peak may not be greater than 5 dBV.

Correspondingly, a frequency difference between the resonant frequency corresponding to the first resonant peak 521 and the resonant frequency corresponding to the second resonant peak 522 (the first resonant frequency corresponding to the first resonant peak 521 is represented by f₀(near the resonant peak 511), the second resonant frequency corresponding to the second resonant peak 522 is represented by f₁, and a frequency difference Δf₁represents the difference between frequencies corresponding to the first resonant peak 521 and the second resonant peak 522, that is, a difference between the first resonant frequency f₀and the second resonant frequency f₁) is within a certain range, which makes the frequency response curve between the resonant peaks 521 and 522 relatively flat. In some embodiments, the frequency difference Δf₁is within a range of 200 Hz-15000 Hz, and a ratio of the frequency difference Δf₁to f₀is within a range of 0.03-8. In some embodiments, the frequency difference Δf₁is within a range of 200 Hz-12000 Hz, and the ratio of the frequency difference Δf₁to f₀is within a range of 0.3-6. In some embodiments, the frequency difference Δf₁is within a range of 200 Hz-8000 Hz, and the ratio of the frequency difference Δf₁to f₀is within a range of 0.3-3. In some embodiments, the frequency difference Δf₁is within a range of 200-3000 Hz, and the ratio of the frequency difference Δf₁to f₀is within a range of 0.2-0.7. In some embodiments, the frequency difference Δf₁is within a range of 200-2000 Hz, and the ratio of the frequency difference Δf₁to f₀is within a range of 0.2-0.65. In some embodiments, the frequency difference Δf₁is within a range of 500-2000 Hz, and the ratio of the frequency difference Δf₁to f₀is within a range of 0.25-0.65. In some embodiments, the frequency difference Δf₁is within a range of 500-1500 Hz, and the ratio of the frequency difference Δf₁to f₀is within a range of 0.25-0.6. In some embodiments, the frequency difference Δf₁is within a range of 800-1500 Hz, and the ratio of the frequency difference Δf₁to f₀is within a range of 0.3-0.6. In some embodiments, the frequency difference Δf₁is within a range of 1000-1500 Hz, and the ratio of the frequency difference Δf₁to f₀is within a range of 0.35-0.6.

Continuing to refer to FIG. 5A, compared with the frequency response curve 510, the frequency response curve 520 has a higher and more stable increase (i.e., the difference, represented by ΔV₁) in sensitivity in a frequency range below the resonant frequency f₁corresponding to the second resonant peak 522. In some embodiments, the increase ΔV₁may be in a range of 10 dBV-60 dBV. In some embodiments, the increase ΔV₁may be in a range of 10 dBV-50 dBV. In some embodiments, the increase ΔV₁may be in a range of 15 dBV-50 dBV. In some embodiments, the increase ΔV₁may be in a range of 15 dBV-40 dBV. In some embodiments, the increase ΔV₁may be in a range of 20 dBV-40 dBV. In some embodiments, the increase ΔV₁may be in a range of 25 dBV-40 dBV. In some embodiments, the increase ΔV₁may be in a range of 30 dBV-40 dBV.

In some embodiments, the resonant system 210 may suppress the resonant peak corresponding to the sensor 100 of the sensing device 200, causing a relatively low Q value at the first resonant peak 521 of the frequency response curve 520 and a flatter frequency response curve in the desired frequency range (e.g., a mid-to-low frequency range), and making a difference (also referred to as a peak-to-valley value, represented by ΔV₂) between a peak value of the highest peak and a valley value of the lowest valley of the overall frequency response curve 520 be within a certain range. In some embodiments, the peak-to-valley value may not exceed 30 dBV. In some embodiments, the peak-to-valley value may not exceed 20 dBV. In some embodiments, the peak-to-valley value may not exceed 10 dBV. In some embodiments, the peak-to-valley value may not exceed 8 dBV. In some embodiments, the peak-to-valley value may not exceed 5 dBV.

In some embodiments, the frequency response of the sensing device 200 may be described by the relevant parameters of the curve 520, such as the peak value and the frequency of the first resonant peak 521, the peak value and the frequency of the second resonant peak 522, the Q value, Δf₁, ΔV₁, ΔV₂, the ratio of Δf₁to f₀, the ratio of the peak-to-valley value to the peak value of the highest peak, and one or more of a first-order coefficient, a second-order coefficient, a third-order coefficient, etc., of an equation determined by fitting the frequency response curve. In some embodiments, when the resonant system 210 includes a vibration pickup unit, the frequency response of the sensing device 200 may be related to the mechanical parameters (e.g., the mass, the damping, the stiffness, etc.) of the mass block and the elastic diaphragm. In some embodiments, when the resonant system 210 is formed by the liquid, e.g., the frequency response of the sensing device 200 in FIG. 2B may be related to the properties of the filled liquid and/or the parameters of the sensor 100. The properties of the liquid may include, e.g., a liquid density, a liquid kinematic viscosity, a liquid volume, the presence or absence of air bubbles, volume of air bubbles, positions of air bubbles, count of air bubbles, etc. The parameters of the sensor 100 may include, e.g., the internal structure, the size, and the stiffness of the housing 110, the mass of the sensor 100, and/or the size, the stiffness of the sensing element 120 (e.g., the cantilever beam), or the like.

FIG. 5B is an exemplary frequency response curve diagram of another sensing device according to some embodiments of the present disclosure. As shown in FIG. 5B, a frequency response curve 560 indicated by a dotted line represents a frequency response curve of the sensor 100, and a frequency response curve 570 indicated by a solid line represents a frequency response curve of the sensing device 200. The frequency response curve 560 may include a resonant peak 561 corresponding to the resonant frequency of the sensor 100. In some embodiments, the relatively high resonant frequency corresponding to the sensor 100 may not be in the desired frequency range (e.g., 100-5000 Hz, 500-7000 Hz, etc.). In some embodiments, the resonant frequency corresponding to the sensor 100 may be in a relatively high frequency range. For example, in some embodiments, the resonant frequency corresponding to the sensor 100 may be higher than 7000 Hz. In some embodiments, the resonant frequency corresponding to the sensor 100 may be higher than 10000 Hz. In some embodiments, the resonant frequency corresponding to the sensor 100 may be higher than 12000 Hz. In some embodiments, the resonant frequency corresponding to the sensor 100 may be higher than 15000 Hz. Correspondingly, since the sensing device 200 has an additional resonant system, the sensing device 200 may have a relatively high rigidity, so that the sensing device 200 may have a relatively high strength and reliability against impact.

The frequency response curve 570 may include a first resonant peak (not shown in the figure) and a second resonant peak 572. In some embodiments, a frequency corresponding to the first resonant peak may be similar to or the same as the resonant frequency corresponding to the sensor 100 in the frequency response curve 560. In some embodiments, the frequency response curve 570 and the frequency response curve 520 in FIG. 5A, except that the first resonant peak shifts to the right, may be substantially the same. A frequency corresponding to the second resonant peak 572 may be in a frequency range that is the same as or similar to a frequency range corresponding to the second resonant peak 522 in FIG. 5A.

In some embodiments, in the desired frequency range (e.g., within 2000 Hz, within 3000 Hz, within 5000 Hz, etc.), a difference between the maximum sensitivity and the minimum sensitivity in the frequency response curve 570 may keep within a certain range to ensure the stability of the sensing device 200. In some embodiments, in the desired frequency range (e.g., a second resonant frequency range), a difference between the minimum sensitivity within a frequency range below the second resonant frequency and the sensitivity of a peak value of the second resonant peak 572 corresponding to the second resonant frequency may not be higher than 40 dBV. In some embodiments, in the desired frequency range (e.g., the second resonant frequency range), the difference between the minimum sensitivity within a frequency range below the second resonant frequency and the sensitivity of a peak value of the second resonant peak 572 corresponding to the second resonant frequency may not be higher than 30 dBV. In some embodiments, in the desired frequency range (e.g., the second resonant frequency range), the difference between the minimum sensitivity within a frequency range below the second resonant frequency and the sensitivity of a peak value of the second resonant peak 572 corresponding to the second resonant frequency may not be higher than 20 dBV. In some embodiments, in the desired frequency range (e.g., the second resonant frequency range), the difference between the minimum sensitivity within a frequency range below the second resonant frequency and the sensitivity of a peak value of the second resonant peak 572 corresponding to the second resonant frequency may not be higher than 10 dBV.

In some embodiments, the difference (the frequency of the first resonant peak is represented by f₀(near the resonant peak 561), the frequency of the second resonant peak 572 is represented by f₁, and a frequency difference Δf₂represents a difference between the resonant frequencies corresponding to the two resonant peaks) between the resonant frequency corresponding to the first resonant peak and the resonant frequency corresponding to the second resonant peak 572 may be in a certain range. In some embodiments, the frequency difference Δf₂may be within a range of 200-15000 Hz, and a ratio of the frequency difference Δf₂to f₀may be within a range of 0.03-8. In some embodiments, the frequency difference Δf₁may be within a range of 200 Hz-12000 Hz, and the ratio of the frequency difference Δf₁to f₀may be within a range of 0.3-6. In some embodiments, the frequency difference Δf₁may be within a range of 200 Hz-8000 Hz, and the ratio of the frequency difference Δf₁to f₀may be within a range of 0.3-3. In some embodiments, the frequency difference Δf₂may be within a range of 1000-6000 Hz, and the ratio of the frequency difference Δf₂to f₀may be within a range of 0.2-0.65. In some embodiments, the frequency difference Δf₂may be within a range of 2000-6000 Hz, and the ratio of the frequency difference Δf₂to f₀may be within a range of 0.3-0.65. In some embodiments, the frequency difference Δf₂may be within a range of 3000-5000 Hz, and the ratio of the frequency difference Δf₂to f₀may be within a range of 0.3-0.5. In some embodiments, the frequency difference Δf₂may be within a range of 3000-4000 Hz, and the ratio of the frequency difference Δf₂to f₀may be within a range of 0.3-0.4.

Further, compared with the frequency response curve 560, the frequency response curve 570 has a higher and more stable increase (i.e., the difference, represented by ΔV₃) in sensitivity in a frequency range below the resonant frequency f₁corresponding to the second resonant peak 522. In some embodiments, the increase ΔV₃may be within a range of 10 dBV-60 dBV. In some embodiments, the increase ΔV₃may be within a range of 10 dBV-50 dBV. In some embodiments, the increase ΔV₃may be within a range of 15 dBV-50 dBV. In some embodiments, the increase ΔV₃may be within a range of 15 dBV-40 dBV. In some embodiments, the increase ΔV₃may be within a range of 20 dBV-40 dBV. In some embodiments, the increase ΔV₃may be within a range of 25 dBV-40 dBV. In some embodiments, the increase ΔV₃may be within a range of 30 dBV-40 dBV.

In some embodiments, the frequency response of the sensing device 200 may be described by the relevant parameters of the curve 570, such as the peak value and frequency of a primary resonant peak, the peak value and frequency of a secondary resonant peak, the Q value, Δf₂, ΔV₃, the ratio of Δf₂to f₀, the ratio of the maximum sensitivity to the minimum sensitivity in the desired frequency range, and one or more of a first-order coefficient, a second-order coefficient, a third-order coefficient, etc., of an equation determined by fitting the frequency response curve. In some embodiments, the frequency response of sensing device 200 may be related to the properties of the filled liquid and/or the parameters of the sensor 100. In some embodiments, in order to obtain an ideal output frequency response (e.g., the frequency response curve 570) of the sensing device 200, the ranges of various parameters (also referred to as frequency response influencing factors, including, for example, properties of the vibration pickup unit and/or the sensor 100) described above that affects the frequency response may be determined through computer simulation, phantom experiments, etc., which is the same as or similar to the method described in FIG. 5A, and is not repeated here.

In some embodiments, when the resonant system 210 is formed by the liquid, e.g., if the liquid is filled between a plurality of elastic diaphragms and forms the resonant system 210 (as shown in FIG. 20), the frequency response of the sensing device 200 may be related to the properties of the filled liquid and/or the parameters of the sensor 100 and the elastic diaphragms. In some embodiments, the properties of the liquid may include, but are not limited to, one or more of the liquid density, the liquid kinematic viscosity, the liquid volume, the presence or absence of air bubbles, the volume of air bubbles, the positions of air bubbles, the count of air bubbles, etc. In some embodiments, the parameters of the sensor 100 may include, but are not limited to, the internal structure, the size, and the stiffness of the housing 110, the mass of the sensor 100, and/or the size, the stiffness, etc., of the sensing element 120 (e.g., the suspension film). In some embodiments, the parameters of the elastic diaphragm may include, but are not limited to, the size, the Young's modulus, the stiffness, the damping, the elongation, the hardness, etc.

In some embodiments, in order to obtain an ideal output frequency response (e.g., the frequency response curve 520) of the sensing device 200, the ranges of various parameters (also referred to as frequency response influencing factors, including, for example, the resonant system (e.g., a vibration pickup unit 620 in FIG. 6) and/or the sensor 100) described above that affects the frequency response may be determined through computer simulation, phantom experiments, etc., which is the same as or similar to the method described in FIG. 5A, and is not repeated here. In some embodiments, an influence of each factor on the sensing device 200 may be determined one by one by controlling variables based on simulation. For example, under a condition that the elastic diaphragm remains constant, the performance of the sensing devices corresponding to mass blocks with different masses may be tested. As another example, under a condition that the same liquid is fully filled, the performance of sensing devices with different cavity structural features may be tested.

In some embodiments, the influence of some factors on the frequency response of the sensing device 200 and the influence of other factors on the frequency response of the sensing device 200 may be related, so the influence of a parameter pair or a parameter set on the frequency response of the sensing device 200 may be determined in the form of the corresponding parameter pair or parameter set. For example, for the resonant system in FIG. 6, when the shape of the mass block 622 changes, the mass and volume of the mass block 622 may change, and a contact area with an elastic diaphragm 621 may also change, so the shape, the mass, the volume, and the contact area (or a ratio of any two parameters, or a product of at least two parameters, etc.) with the elastic diagram 621 may be used as one parameter set to test the performance of the sensing device with different parameter pairs.

For example, for the sensing device 200 having mass blocks with different masses, the larger the mass of the mass block, the smaller the Q value of the frequency response of the sensing device 200.

It should be noted that the above description of the frequency response curve of the sensing device 200 is only an exemplary description, and does not limit the present disclosure to the scope of the illustrated embodiments. It can be understood that after understanding the principle of the system, those skilled in the art may make arbitrary adjustments to its structure and composition without departing from this principle. Such variations are within the protection scope of the present disclosure.

In some embodiments, the resonant system 210 may protect the sensing element by reducing the external impact on the sensing element. For example, the resonant system 210 may include an elastic structure (e.g., an elastic diaphragm), and the elasticity of the elastic structure may absorb the external impact load, reducing the possibility of damage to the sensing device due to the external impact. As another example, the resonant system 210 may also include a mass block made of a polymer material. The elastic property of the mass block of the polymer material may also absorb the external impact load, thereby effectively reducing the stress concentration at a connection position between the elastic diaphragm and the housing 110 of the sensor 100, and reducing the possibility of damage to the sensing device due to the external impact. As another example, if the resonant system 210 is the liquid that fills the cavity of the sensor 100, since the liquid has a viscous effect, and the stiffness of the liquid is much smaller than that of the material of the device, when the sensing device 200 receives the external impact load (e.g., the bone conduction microphone is required to withstand an impact of 10,000 g acceleration without being damaged). Specifically, due to the viscous effect of the liquid, part of the impact energy may be absorbed and consumed, and thus the impact load on the sensing element 120 may be greatly reduced.

It should be noted that the sensing device 200 in the above embodiments may be regarded as additionally arranging the resonant system 210 on the basis of the sensor 100, and the resonant system 210 may be coupled between the housing 110 of the sensor 100 and the sensing element 120. The housing 110 of the sensor 100 may be regarded as the housing of the sensing device 200. In other embodiments, the housing for accommodating the resonant system 210 may also be a housing structure independent of the housing 110 of the sensor 100. The housing structure may be connected to the housing 110 of the sensor 100, and a cavity of the housing structure and a cavity of the housing 110 of the sensor 100 may be spatially connected.

Hereinafter, the sensing device 600 may be described in detail by taking the resonant system formed by the elastic structure (e.g., a structure formed by the combination of the elastic diaphragm and the mass block) as an example.

FIG. 6 is a schematic structural diagram illustrating a sensing device according to some embodiments of the present disclosure. As shown in FIG. 6, the sensing device 600 may include a sensor 610 and a resonant system. In some embodiments, the sensor 610 may include a housing 611, a printed circuit board (PCB) 612, a processor 613, and a sensing element 614. The housing 611 may be a regular or irregular three-dimensional structure with a cavity (i.e., a hollow part) inside. For example, the housing 611 may be a hollow frame structure, including, but is not limited to a regular shape such as a rectangular frame, a circular frame, a regular polygonal frame, and any irregular shape. In some embodiments, the sensing element 614 and the processor 613 may be respectively connected to an upper surface of the PCB 612. The PCB 612 may be located in a cavity inside the housing 611. The housing 611 may seal the sensing element 614, the processor 613, and the PCB 612 and circuits and other components arranged thereon. The PCB 612 may divide the cavity inside the housing 611 into an upper cavity and a lower cavity. The descriptions regarding the housing 611, the PCB 612, the processor 613, and sensing element 614 may be found in the descriptions of the PCB 141, the housing 142, the sensing element 143, and processor 144 in FIG. 1B in the present disclosure, which is not repeated here.

The resonant system may be located in a cavity corresponding to a lower surface of the PCB 612. In some embodiments, the resonant system may include a vibration pickup unit 620. The vibration pickup unit 620 may generate a vibration in response to a vibration of the housing 611, so that in a specific frequency range (e.g., a human voice frequency range), the sensing device 600 may form a second resonant frequency that is lower than a first resonant frequency corresponding to the sensor, thereby improving the sensitivity of the sensing device 600 in the specific frequency range. In some embodiments, the vibration pickup unit 620 may include at least an elastic diaphragm 621 and a mass block 622. The elastic diaphragm 621 may be connected to the housing 611 through a peripheral side of the elastic diaphragm 621. For example, the elastic diaphragm 621 may be connected to an inner wall of the housing 611 by means of gluing, clamping, or the like. The mass block 622 may be arranged on the elastic diaphragm 621. Specifically, the mass block 622 may be arranged on an upper surface or a lower surface of the elastic diaphragm 621. The upper surface of the elastic diaphragm 621 refers to a side of the elastic diaphragm 621 facing the PCB 612, and the lower surface of the elastic diaphragm 621 refers to a side of the elastic diaphragm 621 away from the PCB 612. In some embodiments, there may be a plurality of mass blocks 622. The plurality of mass blocks 622 may be located on the upper surface or the lower surface of the elastic diaphragm 621 simultaneously. In some embodiments, some of the plurality of mass blocks 622 may be arranged on the upper surface of the elastic diaphragm 621, and another part of the mass blocks 622 may be located on the lower surface of the elastic diaphragm 621. In some implementations, the mass block 622 may also be embedded in the elastic diaphragm 621.

In some embodiments, a first acoustic cavity 630 may be formed between the elastic diaphragm 621 and the sensor 610. Specifically, the upper surface of the elastic diaphragm 621, the PCB 612, and the housing 611 may define the first acoustic cavity 630, and the lower surface of the elastic diaphragm 621 and the housing 611 may define a second acoustic cavity 640. When the housing (e.g., the housing 611 of the sensor 610) of the sensing device 600 generates a vibration in response to an external sound signal, since the vibration pickup unit 620 (the elastic diaphragm 621 and the mass block 622) and the housing 611 have different characteristics, the elastic diaphragm 621 and the mass block 622 of the vibration pickup unit 620 may move relative to the housing 611, the elastic diaphragm 621 and the mass block 622 may cause a sound pressure change of the first acoustic cavity 630 during the vibration process relative to the housing 611, and the sensor 610 may convert the external sound signal into an electrical signal based on the sound pressure change in the first acoustic cavity 630. Specifically, the vibration of the elastic diaphragm 621 and the mass block 622 may cause an air vibration in the first acoustic cavity 630, and the air vibration may act on the sensing element 614 through at least one sound inlet 6121 arranged on the PCB 612. The sensing element 614 may convert the air vibration into the electrical signal or generate the electrical signal based on the sound pressure change in the first acoustic cavity 630, and then process the electrical signal through the processor 613. In the embodiments of the present disclosure, by introducing the resonant system on the basis of the sensor 610, the second resonant frequency provided by the resonant system may make the sensing device 600 generate a new resonant peak (e.g., the second resonant peak) in other frequency ranges (e.g., near the second resonant frequency) different from the first resonant frequency of the sensor 610, so that the sensing device 600 may have a relatively high sensitivity in a wider frequency range compared with the sensor. In some embodiments, the second resonant frequency may be adjusted by adjusting mechanical parameters (e.g., the stiffness, the mass, the damping, etc.) of the resonant system, so that the sensitivity of the sensing device 600 may be adjusted. It should be noted that the comparison of the sensitivity of the sensing device with the sensitivity of the sensor 610 in the embodiments of the present disclosure may be understood as a comparison of the sensitivity of the sensor 610 after the resonant system is introduced and the sensitivity of the sensor 610 before the resonant system is introduced.

In this embodiment, the elastic diaphragm 621 may provide the stiffness and the damping to the resonant system, and the mass block 622 may provide the mass and the damping to the resonant system. The combination of the elastic diaphragm 621 and the mass block 622 may be equivalent to a spring-mass-damper system (e.g., the spring (Km₄)-mass (Mm₄)-damping (Rm₄) system in FIG. 2A or the mass-spring-damping system in FIG. 3), thus forming the resonant system. Therefore, the stiffness, the mass, and the damping of the resonant system may be adjusted by adjusting the structure and the material of the elastic diaphragm 621 and/or the mass block 622, so that the second resonant frequency provided by the resonant system may be adjusted, and the sensing device may generate a new resonant peak in the desired frequency range (e.g., near the second resonant frequency), thereby improving sensitivity. In this way, the sensing device 600 may also have a relatively high sensitivity to an external signal of which the frequency is not near the first resonant frequency of the sensor 610.

Further, the sensitivity of the sensing device 600 may be related to the stiffness of the elastic diaphragm 621, the mass of the mass block 622, and a spatial volume of the cavity (i.e., the first acoustic cavity 630) between the elastic diaphragm 621 and the sensor 610. In some embodiments, the smaller the stiffness of the elastic diaphragm 621, the larger the mass of the mass block 622, or the smaller the spatial volume of the first acoustic cavity 630, the higher the sensitivity of the sensing device.

In some embodiments, the mechanical parameters (e.g., the material, the size, the shape, etc.) of the mass block 622 may be adjusted, so that the sensing device 600 may obtain the ideal frequency response, thereby adjusting the resonant frequency and the sensitivity of the sensing device 600, and ensuring the reliability of the sensing device 600. In some embodiments, the mass block 622 may be a regular or irregular shape such as a cuboid, a cylinder, a sphere, an ellipsoid, or a triangle.

In some embodiments, the mass block 622 may be made of polyurethane (PU), polyamide (PA) (commonly known as nylon), polytetrafluoroethylene (PTFE), phenol-formaldehyde plastic (PF), and other polymer materials. The elastic properties of the polymer material mass block 622 may absorb the external impact load, thereby effectively reducing the stress concentration at the connection position between the elastic diaphragm and the housing of the sensor, and further reducing the possibility of damage to the sensing device due to the external impact.

In some embodiments, the stiffness of the elastic diaphragm 621 may be adjusted by adjusting the mechanical parameters (e.g., the Young's modulus, the tensile strength, the elongation, and the hardness shore A) of the elastic diaphragm 621, so that the sensing device 600 can obtain the ideal frequency response, and the resonant frequency and the sensitivity of the sensing device 600 can be adjusted. In some embodiments, in order to improve the sensitivity of the sensing device 600 relative to the sensor 610, the second resonant frequency provided by the resonant system may be lower than the first resonant frequency of the sensor 610. For example, the second resonant frequency may be 1000 Hz˜10000 Hz lower than the first resonant frequency, which may improve the sensitivity of the sensing device 600 by 3 dB-30 dB compared with the sensor 610.

In some embodiments, the elastic diaphragm 621 may be made of flexible polymer materials, wherein the flexible polymer materials may include, but are not limited to, polyimide (PI), parylene, poly Polydimethylsiloxane (Pdms), hydrogel, etc. In some embodiments, the elastic diaphragm 621 may also be made of inorganic rigid materials, wherein the inorganic rigid materials may include, but are not limited to, silicon (Si), silicon dioxide (SiO2) and other semiconductor materials or copper, aluminum, steel, gold, and other metal materials.

In some embodiments, the sensitivity of the sensing device 600 in a specific frequency range (e.g., the human voice frequency range) may be improved by adjusting the Young's modulus of the elastic diaphragm 621. In some embodiments, the greater the Young's modulus of the elastic diaphragm 621, the greater the stiffness, and the higher the sensitivity of the sensing device 600. In some embodiments, the Young's modulus of the elastic diaphragm 621 may be 1 MPa-10 GPa. In some embodiments, the Young's modulus of the elastic diaphragm 621 may be 100 MPa-8 GPa. In some embodiments, the Young's modulus of the elastic diaphragm 621 may be within a range of 1 GPa-8 GPa. In some embodiments, the Young's modulus of the elastic diaphragm 621 may be within a range of 2 GPa-5 GPa. It should be noted that the above specific frequency range refers to a frequency range less than 10000 Hz. For example, the specific frequency range may be within a range of 20 Hz-9000 Hz. As another example, the specific frequency range may be within a range of 500 Hz-6000 Hz. As another example, the specific frequency range may be within a range of 500 Hz-2000 Hz. The specific frequency range may be adaptively adjusted according to different application scenarios of the sensing device 600. For example, when the sensing device 600 is applied to pick up a sound signal when the user speaks, the specific frequency range may be the human voice frequency range. As another example, when the sensing device 600 is applied to pick up a sound signal of an external environment, the specific frequency range may be within a range of 20 Hz-10000 Hz.

In some embodiments, the sensitivity of the sensing device 600 in the specific frequency range (e.g., the human voice frequency range) may be improved by adjusting the tensile strength of the elastic diaphragm 621. The tensile strength of the elastic diaphragm 621 may be the maximum tensile stress that the elastic diaphragm 621 can withstand when a necking phenomenon occurs (i.e., concentrated deformation occurs). In some embodiments, the greater the tensile strength of the elastic diaphragm 621, the higher the sensitivity of the sensing device 600 in the specific frequency range (e.g., the human voice frequency range). In addition, the greater the tensile strength of the elastic diaphragm 621, the better the stability of the resonant system and the entire sensing device. In some embodiments, the tensile strength of the elastic diaphragm 621 may be within a range of 0.5 MPa-100 MPa. In some embodiments, the tensile strength of the elastic diaphragm 621 may be within a range of 5 MPa-90 MPa. In some embodiments, the tensile strength of the elastic diaphragm 621 may be within a range of 10 MPa-80 MPa. In some embodiments, the tensile strength of the elastic diaphragm 621 may be within a range of 20 MPa-70 MPa. The tensile strength of the elastic diaphragm 621 may be within a range of 30 MPa-60 MPa.

In some embodiments, the sensitivity of the sensing device in the specific frequency range (e.g., the human voice frequency range) may be improved by adjusting the elongation of the elastic diaphragm 621. The elongation of the elastic diaphragm 621 refers to a ratio of the maximum elongation length of the elastic diaphragm 621 during a stretching process to an original elongation length. In some embodiments, the greater the elongation of the elastic diaphragm 621, the higher the sensitivity of the sensing device 600 in the specific frequency range (e.g., the human voice frequency range), and the better the stability. In some embodiments, the elongation of the elastic diaphragm 621 may be within a range of 10%-600%. In some embodiments, the elongation of the elastic diaphragm 621 may be within a range of 20%-500%. In some embodiments, the elongation of the elastic diaphragm 621 may be within a range of 50%-400%. In some embodiments, the elongation of the elastic diaphragm 621 may be within a range of 80%-200%.

In some embodiments, the sensitivity of the sensing device in the specific frequency range (e.g., the human voice frequency range) may be improved by adjusting the hardness of the elastic diaphragm 621. The hardness of the elastic diaphragm 621 refers to a Shore hardness (i.e., the hardness Shore A) of the elastic diaphragm 621. In some embodiments, the lower the hardness of the elastic diaphragm 621, the higher the sensitivity of the sensing device. In some embodiments, the hardness Shore A of the elastic diaphragm 621 may be less than 200. In some embodiments, the hardness Shore A of the elastic diaphragm 621 may be less than 150. In some embodiments, the hardness Shore A of the elastic diaphragm 621 may be less than 100. In some embodiments, the hardness Shore A of the elastic diaphragm 621 may be less than 60. In some embodiments, the hardness Shore A of the elastic diaphragm 621 may be less than 30. In some embodiments, the hardness Shore A of the elastic diaphragm 621 may be less than 10.

In some embodiments, the material of the mass block 622 and the material of the elastic diaphragm 621 may be the same. For example, the mass block 622 and the elastic diaphragm 621 may be made of the same polymer material. In some embodiments, when the mass block 622 and the elastic diaphragm 621 are made of the same material, the mass block 622 and the elastic diaphragm 621 may be manufactured in an integrated manner (e.g., 3D printing, and injection molding). When the mass block 622 and the elastic diaphragm 621 are made of the same polymer material, the mechanical parameters of the mass block 622 made of the polymer material and the mechanical parameters (e.g., the Young's Modulus, the stiffness, etc.) of the elastic diaphragm 621 made of the polymer material may be the same or similar, and the frequency response of the mass block 622 and the frequency response of the elastic diaphragm 621 to the vibration signal may be similar, thereby further reducing the stress concentration at the connection position between the elastic diaphragm and the housing during the vibration process.

In some embodiments, the material of the mass block 622 and the material of the elastic diaphragm 621 may be different. For example, the mass block 622 and the elastic diaphragm 621 may be made of different polymer materials or metals respectively, or one of the mass block 622 and the elastic diaphragm 621 may be made of the polymer material, while the other of the mass block 622 and the elastic diaphragm 621 may be made of the metals. In some embodiments, when the mass block 622 and the elastic diaphragm 621 are made of different materials, the mass block 622 may be connected to the elastic diaphragm 621 by means of gluing, clamping, or welding.

In some embodiments, the thickness of the mass block 622 may be in a certain range. In some embodiments, the thickness of the mass block 622 may be within a range of 1 μm-5000 μm. In some embodiments, the thickness of the mass block 622 may be within a range of 1 μm-3000 μm. In some embodiments, the thickness of the mass block 622 may be within a range of 1 μm-1000 μm. In some embodiments, the thickness of the mass block 622 may be within a range of 1 μm-500 μm. In some embodiments, the thickness of the mass block 622 may be within a range of 1 μm-200 μm. In some embodiments, the thickness of the mass block 622 may be within a range of 1 μm-50 μm. In some embodiments, the thickness of the mass block 622 may have a great influence on the resonant peak (e.g., the second resonant peak) of the frequency response curve and the sensitivity of the sensing device 600. Under the same area, the thicker the mass block 622, the greater the total mass, and the smaller the second resonant frequency. The resonant peak (e.g., the second resonant peak) of the sensing device 600 may move forward, and the sensitivity may increase.

In some embodiments, an area of the mass block 622 may be in a certain range. In some embodiments, the area of the mass block 622 may be within a range of 0.1 mm²-100 mm². In some embodiments, the area of the mass block 622 may be within a range of 0.1 mm²-50 mm². In some embodiments, the area of the mass block 622 may be within a range of 0.1 mm²-10 mm². In some embodiments, the area of the mass block 622 may be within a range of 0.1 mm²-6 mm². In some embodiments, the area of the mass block 622 may be within a range of 0.1 mm²-3 mm². In some embodiments, the area of the mass block 622 may be within a range of 0.1 mm²-1 mm². In some embodiments, the area of the mass block 622 may have a great influence on the resonant peak (e.g., the second resonant peak) of the frequency response curve and the sensitivity of the sensing device 600.

In some embodiments, in order to facilitate the adjustment of the mechanical parameters of the elastic diaphragm and realize the adjustment of the stiffness of the resonant system, so as to make the frequency response curve of the sensing device have a relatively good frequency response and improve the resonant frequency and the sensitivity of the sensing device, the elastic diaphragm may also be a multi-layer composite film structure. In some embodiments, the elastic diaphragm may include at least two layers. Wherein, the stiffnesses of the at least two layers of the multi-layer composite film structure may be different.

FIG. 7 is a schematic structural diagram illustrating a sensing device of which an elastic diaphragm is a multi-layer composite film structure according to some embodiments of the present disclosure. A structure of a sensing device 700 may be substantially the same as the structure of the sensing device 600 in FIG. 6. The difference lies in a difference in the elastic diaphragm. A housing 711, a PCB 712, a processor 713, a sensing element 714, a sound inlet 7121, a mass block 722, a first acoustic cavity 730, and a second acoustic cavity 740 in FIG. 7 may be respectively similar to the housing 611, the PCB 612, the processor 613, the sensing element 614, the sound inlet 6121, the mass block 622, the first acoustic cavity 630, and the second acoustic cavity 640 in FIG. 6, which are not repeated here.

Further, as shown in FIG. 7, an elastic diaphragm 721 may be a multi-layer composite diaphragm including a first elastic diaphragm 7211 and a second elastic diaphragm 7212. In some embodiments, the first elastic diaphragm 7211 and the second elastic diaphragm 7212 may be made of the same material or different materials. For example, in some embodiments, the first elastic diaphragm 7211 and the second elastic diaphragm 7212 may be made of the same material (e.g., polyimide). As another example, in some embodiments, one of the first elastic diaphragm 7211 and the second elastic diaphragm 7212 may be made of a polymer material, and the other of the first elastic diaphragm 7211 and the second elastic diaphragm 7212 may be made of another polymer material or metal material. In some embodiments, the stiffness of the first elastic diaphragm 7211 and the stiffness of the second elastic diaphragm 7212 may be different. For example, the stiffness of the first elastic diaphragm 7211 may be greater or less than the stiffness of the second elastic diaphragm 7212. In this embodiment, taking the stiffness of the first elastic diaphragm 7211 being greater than the stiffness of the second elastic diaphragm 7212 as an example, the second elastic diaphragm 7212 may provide required damping to the resonant system, while the stiffness of the first elastic diaphragm 7211 may be relatively high, which ensures that the elastic diaphragm 721 may have high strength, thereby ensuring the reliability of the resonant system and even the entire sensing device 700.

It should be noted that the count of layers of the film structure of the elastic diaphragm in FIG. 7 and related descriptions are only for exemplary description, and do not limit the disclosure to the scope of the embodiments. In some embodiments, the elastic diaphragm in this embodiment may also include more than two layers. For example, the count of film structures may be three layers, four layers, five layers, or more. Merely by way of example, the elastic diaphragm may include a first elastic diaphragm, a second elastic diaphragm, and a third elastic diaphragm connected in sequence from top to bottom, wherein the material, mechanical parameters, and size of the first elastic diaphragm may be the same as the material, mechanical parameters, and size of the third elastic diaphragm, and the material, mechanical parameters, and size of the second elastic diaphragm may be different from the material, mechanical parameters, and size of the first elastic diaphragm or the third elastic diaphragm. For example, the stiffness of the first elastic diaphragm or the third elastic diaphragm may be greater than the stiffness of the second elastic diaphragm. In some embodiments, the mechanical parameters of the elastic diaphragm may be adjusted by adjusting the material, the mechanical parameters, and the size of the first elastic diaphragm, the second elastic diaphragm, and/or the third elastic diaphragm, thereby ensuring the stability of the sensing device 700.

By setting the elastic diaphragm 721 as the multi-layer elastic diaphragm, it may be convenient to adjust the stiffness of the elastic diaphragm 721. For example, the stiffness and the damping of the resonant system may be adjusted by increasing or decreasing the count of the elastic diaphragms (e.g., the first elastic diaphragm 7211 and/or the second elastic diaphragm film 7212), thereby adjusting the second resonant frequency, making the sensing device generate a new resonant peak in the desired frequency range (e.g., near the second resonant frequency), and improving the sensitivity of the sensing device in the specific frequency range. In some embodiments, the elastic diaphragm 721 may be formed by gluing two adjacent layers (e.g., the first elastic diaphragm 7211 and the second elastic diaphragm 7212) of the multi-layer composite film structure.

In some embodiments, the stiffness of the elastic diaphragm 721 may be adjusted by adjusting the mechanical parameters (e.g., the material, the Young's modulus, the tensile strength, the elongation, and the hardness shore A) of at least one elastic diaphragm (the first elastic diaphragm 7211 and/or the second elastic diaphragm) of the elastic diaphragm 721, so that the sensing device 700 may obtain a relatively ideal frequency response, and the resonant frequency and the sensitivity of the sensing device 700 may be adjusted. In some embodiments, in order to improve the sensitivity of the sensing device 700 relatives to the sensor 710, the second resonant frequency provided by the resonant system may be lower than the first resonant frequency of the sensor 710. For example, the second resonant frequency may be 1000 Hz-10000 Hz lower than the first resonant frequency, which may improve the sensitivity of the sensing device 700 by 3 dB-30 dB compared with the sensor 710.

In some embodiments, one layer of the elastic diaphragm 721 may be made of a flexible polymer material, wherein the flexible polymer material may include, but is not limited to, polyimide (PI), parylene, polydimethylsiloxane (Pdms), hydrogel, etc., and another layers of the elastic diaphragm may be made of an inorganic rigid material, wherein the inorganic rigid material may include, but is not limited to, silicon (Si), silicon dioxide (SiO2) and other semiconductor materials or copper, aluminum, steel, gold, and other metal materials.

In some embodiments, the overall tensile strength of the elastic diaphragm 721 may be in a certain range by adjusting the tensile strength of at least one elastic diaphragm of the elastic diaphragm 721, thereby improving the sensitivity of the sensing device 700 in the specific frequency range. In some embodiments, the overall tensile strength of the elastic diaphragm 721 may be within a range of 0.5 MPa-100 MPa by adjusting the material, the thickness, or the size of the first elastic diaphragm 7211 and/or the second elastic diaphragm 7212 of the elastic diaphragm 721. In some embodiments, the overall tensile strength of the elastic diaphragm 721 may be within a range of 5 MPa-90 MPa by adjusting the material or the size of the first elastic diaphragm 7211 and/or the second elastic diaphragm 7212 of the elastic diaphragm 721. In some embodiments, the overall tensile strength of the elastic diaphragm 721 may be within a range of 10 MPa-80 MPa by adjusting the material or the size of the first elastic diaphragm 7211 and/or the second elastic diaphragm 7212 of the elastic diaphragm 721. In some embodiments, the overall tensile strength of the elastic diaphragm 721 may be within a range of 20 MPa-70 MPa by adjusting the material or the size of the first elastic diaphragm 7211 and/or the second elastic diaphragm 7212 of the elastic diaphragm 721. In some embodiments, the overall tensile strength of the elastic diaphragm 721 may be within a range of 30 MPa-60 MPa by adjusting the material, the thickness, or the size of the first elastic diaphragm 7211 and/or the second elastic diaphragm 7212 of the elastic diaphragm 721.

In some embodiments, the overall elongation of the elastic diaphragm 721 may be in a certain range by adjusting the elongation of at least one elastic diaphragm of the elastic diaphragm 721, thereby improving the sensitivity of the sensing device 700 in the specific frequency range. In some embodiments, the greater the elongation of at least one elastic diaphragm of the elastic diaphragm 721, the higher the sensitivity and the better the stability of the sensing device 700. In some embodiments, the overall elongation of the elastic diaphragm 721 may be within a range of 10%-600%. In some embodiments, the overall elongation of the elastic diaphragm 721 may be within a range of 20%-500%. In some embodiments, the overall elongation of the elastic diaphragm 721 may be within a range of 50%-400%. In some embodiments, the overall elongation of the elastic diaphragm 721 may be within a range of 80%-200%.

In some embodiments, the overall hardness of the elastic diaphragm 721 may be in a certain range by adjusting the hardness of at least one elastic diaphragm of the elastic diaphragm 721, thereby improving the sensitivity of the sensing device 700 in the specific frequency range. In some embodiments, the lower the hardness of at least one elastic diaphragm of the elastic diaphragm 721, the higher the sensitivity of the sensing device 700. In some embodiments, the overall Shore A hardness of the elastic diaphragm 721 may be less than 200. In some embodiments, the overall Shore A hardness of the elastic diaphragm 721 may be less than 150. In some embodiments, the overall Shore A hardness of the elastic diaphragm 721 may be less than 100. In some embodiments, the overall Shore A hardness of the elastic diaphragm 721 may be less than 60. In some embodiments, the overall Shore A hardness of the elastic diaphragm 721 may be less than 30. In some embodiments, the overall Shore A hardness of the elastic diaphragm 721 may be less than 10.

In some embodiments, the sensitivity of the sensing device 700 may also be adjusted by adjusting the mechanical parameters (e.g., the material, the size, the shape, etc.) of the mass block 722. The descriptions regarding adjusting the sensitivity of the sensing device 700 by adjusting the mechanical parameters of the mass block 722 may be found in the related descriptions of adjusting the sensitivity of the sensing device 600 by adjusting the mechanical parameters of the mass block 622 in FIG. 6.

In some embodiments, when the parameters (e.g., the Young's modulus, the tensile strength, the hardness, the elongation, etc.) of the elastic diaphragm and the volume or the mass of the mass block are constant, the electrical signal output by the sensing device may be increased by increasing the efficiency of elastic deformation of the elastic diaphragm, thereby improving the acoustic-electric conversion effect of the sensing device. In some embodiments, the efficiency of elastic deformation of the elastic diaphragm may be improved by decreasing a contact area between the mass block and the elastic diaphragm, thereby increasing the electrical signal output by the sensing device.

FIG. 8 is a schematic structural diagram illustrating a sensing device according to some embodiments of the present disclosure. A structure of the sensing device 800 may be substantially the same as the structure of the sensing device 600 in FIG. 6 and the structure of the sensing device 700 in FIG. 7. The difference lies in the difference of the mass block. A housing 811, a PCB 812, a processor 813, a sensing element 814, a sound inlet 8121, an elastic diaphragm 821, a first acoustic cavity 830, and a second acoustic cavity 840 in FIG. 8 may be similar to the housing 611, the PCB 612, the processor 613, the sensing element 614, the sound inlet 6121, the elastic diaphragm 621, the first acoustic cavity 630, the second acoustic cavity 640, etc., in FIG. 6. In addition, the structure of the elastic diaphragm 821 may also be similar to the structure of the elastic diaphragm 721 of the sensing device 700 in FIG. 7, which is not repeated here.

As shown in FIG. 8, a mass block 822 may be an ellipsoid, and a contact area of the mass block 822 with the elastic diaphragm 821 may be less than a projection area of the mass block 822 on the elastic diaphragm 821, which ensures that under the same volume or mass, the mass block 822 and the elastic diaphragm may have a relatively small contact area. When the housing 811 of the sensing device vibrates to drive the mass block 822 to vibrate, the contact region between the elastic diaphragm 821 and the mass block 822 may be approximately regarded as not deformed. By reducing the contact region between the elastic diaphragm 821 and the mass block 822, the region of the elastic diaphragm 821 not contacted with the mass block 822 may be increased, thereby increasing a regional area (i.e., the region of the elastic diaphragm 821 not contacted with the mass block 822) where the elastic diaphragm 821 deforms during the vibration process, increasing an amount of compressed air in the first acoustic cavity 830, making the sensing element 814 of a sensor 810 output a larger electrical signal, and improving the acoustic-electric conversion effect of the sensing device 800. In some embodiments, the mass block 822 may also be a trapezoid, wherein a smaller side of the trapezoid may be connected to the elastic diaphragm 821, so that the contact area between the mass block 822 and the elastic diaphragm may be less than the projection area of the mass block 822 on the elastic diaphragm 821. In some embodiments, the mass block 822 may also be an arch structure. When the mass block 822 is an arch structure, two arch feet of the arch structure may be connected to an upper surface or a lower surface of the elastic diaphragm 822. A contact area between the two arch feet and the elastic diaphragm 821 may be less than a projection area of an arch waist on the elastic diaphragm 821, i.e., the contact area between the mass block 822 of the arch structure and the elastic diaphragm 821 may be less than the projection area of the mass block 822 of the arch structure on the elastic diaphragm 821. It should be noted that in this embodiment, any regular or irregular shape or structure that can meet the requirement that the contact area between the mass block 822 and the elastic diaphragm 821 is less than the projection area of the mass block 822 on the elastic diaphragm 821 may belong to the implementation of the embodiments of the present disclosure, which is not listed one by one.

In some embodiments, the mass block may be a solid structure. For example, the mass block 822 may be a regular or irregular structure such as a solid cylinder, a solid cuboid, a solid ellipsoid, or a solid triangle. In some embodiments, when the mass of the mass block 822 remains constant, in order to reduce the contact area between the mass block 822 and the elastic diaphragm 821, and improve the sensitivity of the sensing device in the specific frequency range, the mass block may also be a partially hollowed structure. For example, as shown in FIG. 9, a mass block 922 may be an annular cylinder. As another example, as shown in FIG. 10, a mass block 1022 may be a rectangular cylindrical structure.

In some embodiments, the mass block may include a plurality of sub-mass blocks separated from each other, and the plurality of sub-mass blocks may be located in different regions of the elastic diaphragm. In some embodiments, the mass block may include two or more sub-mass blocks separated from each other, such as 3 sub-mass blocks, 4 sub-mass blocks, 5 sub-mass blocks, etc. In some embodiments, the mass, size, shape, material, etc., of the plurality of separated sub-mass blocks may be the same or different. In some embodiments, the plurality of separated sub-mass blocks may be distributed at equal intervals, at uneven intervals, symmetrically or asymmetrically on the elastic diaphragm. In some embodiments, the plurality of separated sub-mass blocks may be arranged on the upper surface and/or the lower surface of the elastic diaphragm. By arranging the plurality of separated sub-mass blocks in a middle region of the elastic diaphragm, an area of a deformation region of the elastic diaphragm under the vibration driven by the housing may be increased, the sensitivity of the sensing device may be improved by improving the deformation efficiency of the elastic diaphragm, and the reliability of the resonant system and the sensing device may also be improved. In some embodiments, the plurality of sub-mass blocks may have different frequency responses by adjusting the mass, the size, the shape, the material, and other parameters of the plurality of mass blocks, thereby further improving the sensitivity of the sensing device in different frequency ranges.

FIG. 11 is a schematic cross-sectional view illustrating a sensing device according to some embodiments of the present disclosure. As shown in FIG. 11, a mass block 1122 may include two rectangular cylindrical sub-mass blocks 1122a, 1122b with a certain ratio in size. In some embodiments, the thickness of the sub-mass block 1122a and the thickness (i.e., the thickness of a cylinder wall) of the sub-mass block 1122b may be the same. In some embodiments, the length ratio and the width ratio of the sub-mass block 1122a to the sub-mass block 1122b may be the same. In some embodiments, the length ratio and/or width ratio of the sub-mass block 1122a to the sub-mass block 1122b may be within a range of 0.1-0.8. In some embodiments, the length ratio and/or width ratio of the sub-mass block 1122a to the sub-mass block 1122b may be within a range of 0.2-0.6. In some embodiments, the length ratio and/or width ratio of the sub-mass block 1122a to the sub-mass block 1122b may be within a range of 0.25-0.5. In some embodiments, the two rectangular cylindrical sub-mass blocks 1122a and 1122b may be located in the middle region of the elastic diaphragm 1121, and geometric centers of the two rectangular cylindrical sub-mass blocks 1122a and 1122b may coincide with a geometric center of the elastic diaphragm 1121. In some embodiments, the geometric centers of the rectangular cylindrical sub-mass blocks 1122a and 1122b may not coincide.

It should be noted that the count of sub-mass blocks is not limited to two sub-mass blocks as shown in FIG. 11, and may be three sub-mass blocks, four sub-mass blocks or more. In addition, the shape of the sub-mass block may not be limited to the rectangular cylindrical shape in FIG. 11, and may also be a structure of other shapes. For example, in some embodiments, the mass block 1122 may include two annular sub-mass blocks with different inner diameters. The two annular sub-mass blocks may be both located in the middle region of the elastic diaphragm 1121, and the centers of circles of the two annular sub-mass blocks may coincide with the geometric center of the elastic diaphragm 1121. As another example, the mass block 1122 may include two sub-mass blocks (e.g., an annular sub-mass block and a rectangular sub-mass block) of different shapes, and the larger sub-mass block may surround the smaller sub-mass block. In addition, the plurality of sub-mass blocks may be located on different surfaces of the elastic diaphragm 1121. For example, a portion may be located on an upper surface of the elastic diaphragm 1121, and a portion may be located on a lower surface of the elastic diaphragm 1121.

FIG. 12 is a schematic cross-sectional view illustrating a sensing device according to some embodiments of the present disclosure. As shown in FIG. 12, a mass block 1222 may include four sub-mass blocks 1222c, 1222d, 1222e, and 1222f. The sub-mass blocks 1222c, 1222d, 1222e, and 1222f may be distributed in a matrix in a middle region of the elastic diaphragm 1221. The sub-mass blocks 1222c, 1222d, 1222e and 1222f may have any regular or irregular shape such as a rectangle, a circle, or an ellipse. In some embodiments, the shape, size, material, etc., of the sub-mass blocks 1222c, 1222d, 1222e, and 1222f may be the same or different.

FIG. 13 is a schematic cross-sectional view illustrating a sensing device according to some embodiments of the present disclosure. As shown in FIG. 13, a mass block 1322 may include four sub-mass blocks 1322g, 1322h, 1322i, and 1222j. The sub-mass blocks 1322g, 1322h, 1322i, and 1322j may be distributed in a ring at equal intervals in a middle region of the elastic diaphragm 1321, and a center of the circle of the ring may coincide with a geometric center of an elastic diaphragm 1321.

It should be noted that the count, the shape, and the distribution of the sub-mass blocks in FIGS. 11-13 are only for exemplary description, and are not intended to limit the present disclosure. For example, the count of the rectangular cylindrical sub-mass blocks in FIG. 11 and the sub-mass blocks in FIG. 13 may be more than two (e.g., 3, 4, 5), etc. As another example, the count of sub-mass blocks in FIG. 12 may be that the 6 sub-mass blocks are distributed in a 2×3 matrix, or the 8 sub-mass blocks are distributed in a 4×4 matrix.

It should be noted that the sensing devices 900, 1000, 1100, 1200, and 1300 in FIGS. 9-13 may be substantially the same in structure as the sensing devices 600, 700, or 800 in FIGS. 6-8. The difference between the sensing devices 900, 1000, 1100, 1200, and 1300 and the sensing devices 600, 700, or 800 lies in the difference in the mass block. The descriptions regarding the housings 911, 1011, 1111, 1211, and 1311 and the elastic diaphragms 921, 1021, 1121, 1221, and 1321 respectively shown in FIGS. 9-13 may be found in the descriptions of the housings and the elastic diaphragms in FIGS. 6-8.

Please continue to refer to the sensing device 600 in FIG. 6, in some embodiments, the size (e.g., the height, i.e., the distance between the elastic diaphragm 621 and the PCB 612, or the area in a horizontal direction) of the first acoustic cavity 630 may have a great influence on the sensitivity of the sensing device 600. In some embodiments, the height of the first acoustic cavity 630 may be within a range of 0.1 μm-5000 μm. In some embodiments, the height of the first acoustic cavity 630 may be within a range of 0.1 μm-3000 μm. In some embodiments, the height of the first acoustic cavity 630 may be within a range of 0.1 μm-1000 μm. In some embodiments, the height of the first acoustic cavity 630 may be within a range of 0.1 μm-500 μm. In some embodiments, the height of the first acoustic cavity 630 may be within a range of 0.1 μm-200 μm. In some embodiments, the height of the first acoustic cavity 630 may be within a range of 0.1 μm-100 μm. In some embodiments, the smaller the height of the first acoustic cavity 630, the higher the sensitivity of the sensing device 600 in the specific frequency range under the premise that the resonant frequency and other parameters are consistent.

In some embodiments, the area of the first acoustic cavity 630 in the horizontal direction may be within a range of 1 mm²-100 mm². In some embodiments, the area of the first acoustic cavity 630 in the horizontal direction may be within a range of 1 mm²-50 mm². In some embodiments, the area of the first acoustic cavity 630 in the horizontal direction may be within a range of 1 mm²-20 mm². In some embodiments, the area of the first acoustic cavity 630 in the horizontal direction may be within a range of 1 mm²-10 mm². In some embodiments, the area of the first acoustic cavity 630 in the horizontal direction may be within a range of 1 mm²-6 mm². In some embodiments, the area of the first acoustic cavity 630 in the horizontal direction may be within a range of 1 mm²-3 mm². In some embodiments, the smaller the area of the first acoustic cavity 630 in the horizontal direction, the smaller the spatial volume of the first acoustic cavity 630, and the higher the sensitivity of the sensing device 600 in the specific frequency range.

It should be noted that the description about the first acoustic cavity 630 may also be applicable to the first acoustic cavity 730 of the sensing device 700 in FIG. 7 and the first acoustic cavity 830 of the sensing device 800 in FIG. 8. Therefore, the descriptions regarding the first acoustic cavity 730 and the first acoustic cavity 830 may be found in the descriptions of the first acoustic cavity 630.

For example, FIG. 14 is a schematic structural diagram illustrating a sensing device according to some embodiments of the present disclosure. A sensing device 1400 in FIG. 14 may be substantially the same in structure as the sensing devices 600, 700, 800, 900, 1000, 1100, 1200, and 1300 in FIGS. 6-13 respectively. The difference lies in the area of the elastic diaphragm. Therefore, the descriptions regarding a housing 1411, a PCB 1412, a processor 1413, a sensing element 1414, a sound inlet 14121, a mass block 1422, a first acoustic cavity 1430, and a second acoustic cavity 1440 in FIG. 14 may be found in the relevant descriptions of the housing, the PCB, the processor, the sensing element, the sound inlet, the mass block, the first acoustic cavity, and the second acoustic cavity in FIGS. 6-13, which is not repeated here.

An area of the elastic diaphragm 1421 of the sensing device 1400 in FIG. 14 may be less than an area of the PCB. The elastic diaphragm may be located opposite the sound inlet. Correspondingly, the portion of the housing 1410 connected to the elastic diaphragm may be adapted to the size of the elastic diaphragm. By setting in this way, the area of the elastic diaphragm 1421 in the horizontal direction may be reduced, i.e., the area of the first acoustic cavity 1430 in the horizontal direction may also be reduced, and a spatial volume of the first acoustic cavity 1430 may be reduced, thereby improving the sensitivity of the sensing device 1400 in a specific frequency range.

FIG. 15 is a schematic structural diagram illustrating a sensing device of which an elastic diaphragm includes a first hole according to some embodiments of the present disclosure. A structure of a sensing device 1500 in FIG. 15 may be substantially the same as the structure of the sensing device 600 in FIG. 6. The difference lies in that a first hole 15211 may be arranged on an elastic diaphragm 1521 in FIG. 15. A housing 1511, a PCB 1512, a processor 1513, a sensing element 1514, a sound inlet 15121, a mass block 1522, a first acoustic cavity 1530, and a second acoustic cavity 1540 in FIG. 15 may be respectively similar to the housing 611, the PCB 612, the processor 613, the sensing element 614, the sound inlet 6121, the mass block 622, the first acoustic cavity 630, and the second acoustic cavity 640 in FIG. 6, which is not repeated here.

In some embodiments, as shown in FIG. 15, the elastic diaphragm 1521 may include at least one first hole 15211. The at least one first hole 15211 may enable fluid communication between the first acoustic cavity 1530 and at least one second acoustic cavity, so as to adjust air pressure in the first acoustic cavity 1530 and the second acoustic cavity 1540, balance an air pressure difference in the two cavities, prevent damage to the sensing device 1500, and increase the damping of the resonant system to reduce a quality factor Q value of the sensing device 1500, thereby making a frequency response curve of the sensing device 1500 flatter. The second acoustic cavity 1540 refers to a cavity defined between the elastic diaphragm 1521 and the housing 1511, which may be different from the first acoustic cavity 1530.

FIG. 16 is a schematic cross-sectional view illustrating a sensing device shown in FIG. 15. In some embodiments, as shown in FIG. 16, at least one first hole 15211 may be located in a region on the elastic diaphragm 1521 not covered by the mass block 1522. In some embodiments, a count of first holes 21111 on the elastic diaphragm 1521 may be set according to an actually required damping. For example, a count of the first holes 15211 may be 4, 8, 16, etc. In some embodiments, the plurality of first holes 15211 may be distributed at equal intervals in a rectangle or in a ring in a region on the elastic diaphragm 1521 not covered by the mass block 1522.

In some embodiments, the mass block may include at least one second hole. The at least one second hole may be in fluid communication with the at least one first hole, to adjust the air pressure in the first acoustic cavity and the second acoustic cavity, and adjust the damping of the resonant system, thereby making the frequency response curve of the sensing device flatter.

FIG. 17 is a schematic cross-sectional view illustrating a sensing device according to some embodiments of the present disclosure. A sensing device 1700 in FIG. 17 may be substantially the same in structure as the sensing device 1500 in FIG. 15 or FIG. 16. The difference lies in that a second hole 17221 may be arranged on a mass block 1722 of the sensing device 1700 in FIG. 17. The descriptions regarding a housing 1711 and an elastic diaphragm 1721 in FIG. 17 may be found in the relevant descriptions regarding the housing and the elastic diaphragm in FIG. 15 or FIG. 16 (or FIGS. 6-14).

In some embodiments, as shown in FIG. 17, a plurality of second holes 17221 may be arranged on the mass block 1722, and a plurality of first holes 17211 may be arranged on the elastic diaphragm 1721, wherein a portion of the plurality of first holes 17211 may be located in a region on the elastic diaphragm 1721 covered by the mass 1722, and correspond to the second holes 17221 in position. The first holes 17211 located in the region on the elastic diaphragm 1721 covered by the mass block 1722 may be in fluid communication with the corresponding second holes 17221, so as to ensure that the first acoustic cavity 1730 and the second acoustic cavity 1740 may be spatially connected. In addition, another portion of the first holes 17211 may be arranged in a region on the elastic diaphragm 1721 not covered by the mass block 1722, which may also implement a spatial connection between the first acoustic cavity 1730 and the second acoustic cavity 1740.

In some embodiments, the diameter of the first holes (e.g., the first holes 15211 in FIG. 15 or the first holes 17211 in FIG. 17) or the second holes 17221 may be within a range of 0.01 μm-40 μm. In some embodiments, the diameter of the first holes or the second holes 17221 may be within a range of 0.03 μm-30 μm. In some embodiments, the diameter of the first holes or the second holes 17221 may be within a range of 0.05 μm-20 μm.

In some embodiments, instead of arranging the first holes on the elastic diaphragm or the second holes on the mass block, the elastic diaphragm may be manufactured by using a film material containing micropores. In this embodiment, the micropores of the elastic diaphragm may play the role of air conduction, and may also implement adjustment of air pressure in the acoustic cavity and damping adjustment of the resonant system.

In this embodiment, the elastic diaphragm may use a microporous film made of polytetrafluoroethylene (PTFE), nylon, polyethersulfone (PES), polyvinylidene fluoride (PVDF), polypropylene (PP), or other materials. Preferably, the elastic diaphragm may use a microporous film made of PTFE. In some embodiments, a pore diameter of the microporous film may be within a range of 0.01 μm-10 μm. In some embodiments, the pore diameter of the microporous film may be within a range of 0.05 μm-10 μm. In some embodiments, the pore diameter of the microporous film may be within a range of 0.1 μm-10 μm. The elastic diaphragm may use the microporous film, which may eliminate punching holes on the elastic diaphragm or the mass block, thereby simplifying the manufacturing process and saving cost.

In some embodiments, the elastic diaphragm may further include at least one elastic layer (not shown in the figure). The at least one elastic layer may be located in a region on the elastic diaphragm not covered by the mass block. The at least one elastic layer may cover at least part of the first holes or the micropores on the elastic diaphragm. On the one hand, the porosity of the micropores of the first holes may be adjusted, and on the other hand, the stiffness of the elastic diaphragm may be adjusted, thereby adjusting the sensitivity and the reliability of the sensing device 200. In some embodiments, a material of the elastic layer may be silica gel, silicone gel, or the like. In some embodiments, the thickness of the elastic layer may be within a range of 0.1 μm-500 μm. In some embodiments, the thickness of the elastic layer may be within a range of 0.5 μm-300 μm. In some embodiments, the thickness of the elastic layer may be within a range of 1 μm-100 μm. In some embodiments, the thickness of the elastic layer may be within a range of 50 μm-100 μm.

In some embodiments, a filler with fluidity may be arranged in at least one second acoustic cavity (e.g., the second acoustic cavities 640, 740, and 840 in FIGS. 6-8, etc.) different from the first acoustic cavity (e.g., the first acoustic cavities 630, 730, and 830 in FIGS. 6-8) of the sensing device. Taking the sensing device 600 in FIG. 6 as an example, the second acoustic cavity 240 may be a cavity defined between the elastic diaphragm 621 and/or the mass block 622 and the housing 611 of the sensor. By arranging the filler with fluidity in the second acoustic cavity 640, the quality factor Q value and the sensitivity of the sensing device 600 may be adjusted, and when the sensing device 600 is impacted, the filler with fluidity may also absorb the impact load to prevent the sensing device 600 from being damaged. In some embodiments, the greater the kinematic viscosity of the filler, the higher the sensitivity of the sensing device 600. In some embodiments, the kinematic viscosity of the filler may be within 20,000 cst. In some embodiments, the kinematic viscosity of the filler may be within 10,000 cst. In some embodiments, the kinematic viscosity of the filler may be within 5000 cst. In some embodiments, the kinematic viscosity of the filler may be within 500 cst. In some embodiments, the kinematic viscosity of the filler may be within 50 cst. In some embodiments, the filler with fluidity in the second acoustic cavity 640 may include liquid, gas, gel, and other flexible materials. Preferably, a material of the filler with fluidity in the second acoustic cavity 640 may be oil, aloe gel, silicone gel, polydimethylsiloxane (PDMS), or the like. In some embodiments, the filler with fluidity may be completely filled or incompletely filled (e.g., there may be air bubbles) in the second acoustic cavity 640.

In some embodiments, the sensing device may include a plurality of resonant systems, which may implement multi-mode vibration of the sensing device and improve the sensitivity of the sensing device in a wider frequency range.

FIG. 18 is a schematic structural diagram illustrating a sensing device including a plurality of resonant systems according to some embodiments of the present disclosure. As shown in FIG. 18, a sensing device 1900 may include a sensor 1910, a first resonant system, and a second resonant system. In some embodiments, the first resonant system may include a first vibration pickup unit 1920 and a second vibration pickup unit 1930. The first vibration pickup unit 1920 may include a first elastic diaphragm 1921 and a first mass block 1922. The second vibration pickup unit 1930 may include a second elastic diaphragm 1931 and a second mass block 1932. In some embodiments, the sensor 1910 may include a housing 1911, a printed circuit board (PCB) 1912, a processor 1913, and a sensing element 1914. The descriptions regarding the housing 1911, the PCB 1912, the processor 1913, and the sensing element 1914 may be found in the descriptions of the PCB 141, the housing 142, the sensing element 143, and the processor 144 in FIG. 1B or the relevant descriptions regarding the housing 611, the PCB 611, the sensing element 614, and the processor 613 in FIG. 6 of the present disclosure, which is not repeated here. In addition, the first elastic diaphragm 1921, the second elastic diaphragm 1931, the first mass block 1922, and the second mass block 1932 in this embodiment may be similar (e.g., have the same material, structure, shape, size, stiffness, damping, and other mechanical parameters) to the elastic diaphragms and the mass blocks in other embodiments of the present disclosure. Therefore, in this embodiment, more descriptions regarding the first elastic diaphragm 1921, the second elastic diaphragm 1931, the first mass block 1922, and the second mass block 1932 may be found elsewhere in the present disclosure (e.g., the relevant descriptions regarding the elastic diaphragms and the mass blocks in FIGS. 6-18).

Further, the first elastic diaphragm 1921 may be connected to the housing 1911 through a peripheral side of the first elastic diaphragm 1921, the second elastic diaphragm 1931 may be connected to the housing 1911 through a peripheral side of the second elastic diaphragm 1931, and the first elastic diaphragm 1921 and the second elastic diaphragm 1931 may be arranged in sequence from top to bottom. In this embodiment, the first resonant system may provide a third resonant frequency, and the second resonant system may provide a fourth resonant frequency. When the housing 1911 of the sensing device 1900 generates a vibration due to an external signal, the first resonant system and the second resonant system may be simultaneously driven to vibrate, so as to cause a vibration of air in a cavity (i.e., a third acoustic cavity 1940) defined between first elastic diaphragm 1921 and the second elastic diaphragm 1931, a cavity (i.e., a fourth acoustic cavity 1950) defined between the first elastic diaphragm 1921 and the sensor 1910, and a cavity (i.e., a fifth acoustic cavity 1960) defined between the second elastic diaphragm 1931 and the housing 1911, thereby causing a sound pressure change in the third acoustic cavity 1940, the fourth acoustic cavity 1950, and the fifth acoustic cavity 1960. In some embodiments, the first elastic diaphragm 1921 and the second elastic diaphragm 1931 may be a microporous film or a film structure with holes (e.g., the first holes 15211 or 17211 in FIGS. 15-17), so that the sound pressure changes in the third acoustic cavity 1940, the fourth acoustic cavity 1950, and the fifth acoustic cavity 1960 may be transmitted to the sensing element 1914 through the holes. The first vibration pickup unit 1920 and the second vibration pickup unit 1930 may have different frequency responses. By setting two or more resonant systems, multi-mode vibration of the sensing device 1900 may be realized, and the sensitivity of the sensing device in a wider frequency range may be improved.

In some embodiments, a third resonant frequency of the first resonant system and a fourth resonant frequency of the second resonant system may be different by adjusting mechanical parameters (e.g., mass, material, shape, size, a stiffness, damping, etc.) of components (e.g., the first elastic diaphragm 1921, the second elastic diaphragm 1931, the first mass block 1922, and the second mass block 1932) of the first resonant system and the second resonant system. In some embodiments, the difference between the third resonant frequency and the fourth resonant frequency may be less than 2000 Hz. In some embodiments, the difference between the third resonant frequency and the fourth resonant frequency may be less than 1000 Hz. In some embodiments, the difference between the third resonant frequency and the fourth resonant frequency may be less than 800 Hz. In some embodiments, the difference between the third resonant frequency and the fourth resonant frequency may be less than 500 Hz.

It should be noted that the count of resonant systems in FIG. 18 is only used for exemplary description and is not limited thereto. In some embodiments, the count of resonant systems of the sensing device may be more than two. For example, the sensing device may further include a third resonant system, a fourth resonant system, or the like. When the sensing device includes a plurality of resonant systems, the elastic diaphragm of each resonant system may be a film structure with holes or a microporous film, so that the sound pressure change in each cavity may be transmitted to the sensing element. The plurality of resonant systems may have different frequency responses. By setting two or more resonant systems, the multi-mode vibration of the sensing device may be realized, and the sensitivity of the sensing device in a wider frequency range may be improved.

In some embodiments, the plurality of resonant systems of the sensing device may also be composed of liquid and/or air bubbles filled in the housing of the sensing device (or sensor). For example, liquids of different types, densities, and kinematic viscosities may be filled in the housing of the sensing device (or sensor), and various liquids or liquids of different densities and kinematic viscosities may form a resonant system independently. As another example, the housing of the sensing device (or sensor) may not be completely filled with liquid so air bubbles may exist therein, wherein the liquid may serve as one resonant system, and the air bubbles may serve as another resonant system.

By setting the sensing device to include the plurality of resonant systems, the frequency response curve of the sensing device may generate new resonant peaks in a plurality of frequency ranges (e.g., near the third resonant frequency or near the fourth resonant frequency), thereby improving the sensitivity of the sensing device in a specific frequency range, and expanding the frequency range corresponding to a high sensitivity of the sensing device.

The basic concept has been described above. Obviously, for those skilled in the art, the above detailed disclosure is only an example, and does not constitute a limitation to the present disclosure. Although not explicitly stated here, those skilled in the art may make various modifications, improvements, and amendments to the present disclosure. These alterations, improvements, and modifications are intended to be suggested by this disclosure, and are within the spirit and scope of the exemplary embodiments of this disclosure.

Moreover, certain terminology has been used to describe embodiments of the present disclosure. For example, “one embodiment,” “an embodiment,” and/or “some embodiments” refer to a certain feature, structure, or characteristic related to at least one embodiment of the present disclosure. Therefore, it should be emphasized and noted that references to “one embodiment,” or “an embodiment” or “an alternative embodiment” two or more times in different places in the present disclosure do not necessarily refer to the same embodiment. In addition, some features, structures, or features in the present disclosure of one or more embodiments may be appropriately combined.

In addition, those skilled in the art will understand that various aspects of the present disclosure may be illustrated and described in several patentable categories or circumstances, including any new and useful processes, machines, products, substances, or combinations thereof, or any new and useful improvements on them. Accordingly, all aspects of the present disclosure may be performed entirely by hardware, may be performed entirely by software (including firmware, resident software, microcode, etc.), or may be performed by a combination of hardware and software. The above hardware or software can be referred to as “data block,” “module,” “engine,” “unit,” “component” or “system.” In addition, aspects of the present disclosure may appear as a computer product located in one or more computer-readable media, the product including computer-readable program code.

A computer storage medium may contain a propagated data signal embodying a computer program code, for example, on a baseband or as part of a carrier wave. The propagated signal may have various manifestations, including electromagnetic form, optical form, etc., or a suitable combination. The computer storage medium may be any computer-readable medium, other than a computer-readable storage medium, that can be used to communicate, propagate, or transfer a program for use by being coupled to an instruction execution system, apparatus, or device. Program codes residing on the computer storage medium may be transmitted over any suitable medium, including radio, electrical cable, fiber optic cable, RF, or the like, or combinations of any of the foregoing.

In addition, the order of processing elements and sequences described in the present disclosure, the use of numbers and letters, or the use of other names are not used to limit the order of the process and methods of the present disclosure unless explicitly stated in the claims. Although the above disclosure discusses through various examples what is currently considered to be a variety of useful embodiments of the disclosure, it is to be understood that such detail is solely for that purpose, and that the appended claims are not limited to the disclosed embodiments, but, on the contrary, are intended to cover modifications and equivalent arrangements that are within the spirit and scope of the disclosed embodiments. For example, although the implementation of various components described above may be embodied in a hardware device, it may also be implemented as a software only solution, e.g., an installation on an existing server or mobile device.

Similarly, it should be appreciated that in the foregoing description of embodiments of the present disclosure, various features are sometimes grouped together in a single embodiment, figure, or description thereof for the purpose of streamlining the disclosure aiding in the understanding of one or more of the various embodiments. However, this disclosure does not mean that the present disclosure object requires more features than the features mentioned in the claims. Rather, claimed subject matter may lie in less than all features of a single foregoing disclosed embodiment.

In some embodiments, counts describing the quantity of components and attributes are used. It should be understood that such counts used in the description of the embodiments use the modifiers “about,” “approximately” or “substantially” in some examples. Unless otherwise stated, “about,” “approximately” or “substantially” indicates that the stated figure allows for a variation of ±20%. Accordingly, in some embodiments, the numerical parameters used in the disclosure and claims are approximations that can vary depending upon the desired characteristics of individual embodiments. In some embodiments, numerical parameters should consider the specified significant digits and adopt the general digit retention method. Although the numerical ranges and parameters used in some embodiments of the present disclosure to confirm the breadth of the range are approximations, in specific embodiments, such numerical values are set as precisely as practicable.

Each of the patents, patent applications, publications of patent applications, and other material, such as articles, books, specifications, publications, documents, things, and/or the like, referenced herein is hereby incorporated herein by this reference in its entirety for all purposes, excepting any prosecution file history associated with same, any of same that is inconsistent with or in conflict with the present document, or any of same that may have a limiting affect as to the broadest scope of the claims now or later associated with the present document. By way of example, should there be any inconsistency or conflict between the description, definition, and/or the use of a term associated with any of the incorporated material and that associated with the present document, the description, definition, and/or the use of the term in the present document shall prevail.

At last, it should be understood that the embodiments described in the present disclosure are merely illustrative of the principles of the embodiments of the present disclosure. Other modifications that may be employed may be within the scope of the present disclosure. Thus, by way of example, but not of limitation, alternative configurations of the embodiments of the present disclosure may be utilized in accordance with the teachings herein. Accordingly, embodiments of the present disclosure are not limited to that precisely as shown and described.

	Number	Date	Country
Parent	PCT/CN2021/112014	Aug 2021	US
Child	18353059		US

SENSING DEVICES

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