WO2024230765A1 - 麦克风 - Google Patents

麦克风 Download PDF

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Publication number
WO2024230765A1
WO2024230765A1 PCT/CN2024/091858 CN2024091858W WO2024230765A1 WO 2024230765 A1 WO2024230765 A1 WO 2024230765A1 CN 2024091858 W CN2024091858 W CN 2024091858W WO 2024230765 A1 WO2024230765 A1 WO 2024230765A1
Authority
WO
WIPO (PCT)
Prior art keywords
diaphragm
guide hole
sound guide
back plate
condenser microphone
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/CN2024/091858
Other languages
English (en)
French (fr)
Inventor
邓文俊
袁永帅
黄雨佳
周文兵
廖风云
齐心
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Shenzhen Shokz Co Ltd
Original Assignee
Shenzhen Shokz Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Shenzhen Shokz Co Ltd filed Critical Shenzhen Shokz Co Ltd
Priority to EP24803044.7A priority Critical patent/EP4564851A4/en
Priority to CN202480013675.1A priority patent/CN120712793A/zh
Publication of WO2024230765A1 publication Critical patent/WO2024230765A1/zh
Priority to US19/079,518 priority patent/US20250220360A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
    • H04R1/00—Details of transducers, loudspeakers or microphones
    • H04R1/20—Arrangements for obtaining desired frequency or directional characteristics
    • H04R1/32—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only
    • H04R1/34—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only by using a single transducer with sound reflecting, diffracting, directing or guiding means
    • H04R1/38—Arrangements for obtaining desired frequency or directional characteristics for obtaining desired directional characteristic only by using a single transducer with sound reflecting, diffracting, directing or guiding means in which sound waves act upon both sides of a diaphragm and incorporating acoustic phase-shifting means, e.g. pressure-gradient microphone
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
    • H04R1/00—Details of transducers, loudspeakers or microphones
    • H04R1/08—Mouthpieces; Microphones; Attachments therefor
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
    • H04R1/00—Details of transducers, loudspeakers or microphones
    • H04R1/08—Mouthpieces; Microphones; Attachments therefor
    • H04R1/083—Special constructions of mouthpieces
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
    • H04R19/00—Electrostatic transducers
    • H04R19/005—Electrostatic transducers using semiconductor materials
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
    • H04R19/00—Electrostatic transducers
    • H04R19/04—Microphones
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; ELECTRIC HEARING AIDS; PUBLIC ADDRESS SYSTEMS
    • H04R2410/00—Microphones
    • H04R2410/03—Reduction of intrinsic noise in microphones

Definitions

  • the present invention relates to the field of acoustics, and in particular to a microphone that performs acoustic-electric conversion under the action of the viscosity of air molecules.
  • One of the embodiments of the present specification provides a capacitive microphone, including a diaphragm, a first hole array for allowing airflow to pass through the diaphragm; and a back plate, a second hole array for allowing airflow to pass through the back plate, the diaphragm and the back plate are relatively spaced apart to form a capacitor.
  • the diameter of each hole in the first hole array on the diaphragm is in the range of 5 ⁇ m-50 ⁇ m; or the diameter of each hole in the second hole array on the back plate is in the range of 5 ⁇ m-50 ⁇ m.
  • the spacing between two adjacent holes in the first hole array on the diaphragm is in the range of 0.1 ⁇ m-50 ⁇ m; or the spacing between two adjacent holes in the second hole array on the back plate is in the range of 0.1 ⁇ m-50 ⁇ m.
  • the distance between the back plate and the diaphragm is in the range of 0.5 ⁇ m-20 ⁇ m.
  • the positions of the diaphragms and the holes on the back plate correspond one to one.
  • a substrate is further included, and the peripheral side of the diaphragm is elastically connected to the substrate.
  • the peripheral side of the diaphragm is elastically connected to the substrate via a plurality of symmetrically distributed elastic structures.
  • the peripheral side of the back plate is rigidly connected to the base.
  • a protruding structure is provided on the surface of the back plate facing the diaphragm or on the surface of the diaphragm facing the back plate.
  • the back plate includes a conductor layer and an insulating layer, and the conductor layer is between the insulating layer and the diaphragm.
  • the back plate includes a conductor layer and an insulating layer, wherein the insulating layer is between the conductor layer and the diaphragm.
  • the material of the diaphragm includes at least one of the following materials: polysilicon, polyparaxylene, polyimide or metal.
  • the back plate includes a first back plate and a second back plate, the first back plate and the second back plate are respectively arranged on both sides of the diaphragm, the diaphragm and the first back plate are relatively separated to form a first capacitor, and the diaphragm and the second back plate are relatively separated to form a second capacitor.
  • the thickness of the diaphragm is in the range of 0.1 ⁇ m-10 ⁇ m.
  • the insulating layer is made of silicon oxide or silicon nitride
  • the conductive layer is made of polysilicon or metal.
  • the first hole array is unevenly distributed on the diaphragm.
  • the condenser microphone also includes a shell that accommodates the diaphragm and the back plate, the shell having a first sound guide hole and a second sound guide hole, the first sound guide hole establishing a first acoustic path for air to flow to the surface of the diaphragm facing away from the back plate, and the second sound guide hole establishing a second acoustic path for air to flow to the surface of the diaphragm facing the back plate.
  • the first acoustic path and the second acoustic path have equal path lengths.
  • the first sound guiding hole and the second sound guiding hole have equal opening areas.
  • the first acoustic path and the second acoustic path have unequal path lengths.
  • the ratio of the absolute value of the difference between the path lengths of the first acoustic path and the second acoustic path to the path length of the first acoustic path is not less than 10%; or, the ratio of the absolute value of the difference between the path lengths of the first acoustic path and the second acoustic path to the path length of the second acoustic path is not less than 10%.
  • an area of the first sound guide hole is different from an area of the second sound guide hole.
  • the ratio of the absolute value of the difference between the areas of the first sound guide hole and the second sound guide hole to the area of the first sound guide hole is not less than 10%; or, the ratio of the absolute value of the difference between the areas of the first sound guide hole and the second sound guide hole to the area of the second sound guide hole is not less than 10%.
  • acoustic resistance members corresponding to different acoustic resistance sizes are arranged at the first sound guide hole and the second sound guide hole, respectively.
  • an acoustic delay element is arranged in the first acoustic path and/or the second acoustic path, and the acoustic delay element is configured to extend the physical length of the corresponding acoustic path.
  • the first acoustic path and/or the second acoustic path each include at least one bend.
  • An embodiment of the present specification also provides a capacitive microphone, including a substrate; a fixed electrode, which is fixed on the substrate; and a movable electrode, which is fixed on the substrate, wherein the fixed electrode and the movable electrode are arranged to be relatively spaced apart in a first direction to form a capacitor, and the movable electrode is configured to vibrate along a second direction perpendicular to the first direction, and the vibration changes the facing area of the fixed electrode and the movable electrode along the first direction.
  • the fixed electrode includes a plurality of first electrodes arranged at intervals along a first direction
  • the movable electrode includes a plurality of second electrodes distributed at intervals along the first direction
  • one end of the movable electrode is fixed to the substrate.
  • both ends of the movable electrode are fixed to the substrate.
  • the movable electrode has a curved structure.
  • the width of the curved structure is in the range of 0.1 ⁇ m-30 ⁇ m.
  • the thickness of the curved structure is in the range of 0.1 ⁇ m-30 ⁇ m.
  • the fixed electrode includes a plurality of sub-electrode layers distributed along the second direction, and every two adjacent sub-electrode layers are separated by a sub-insulating layer.
  • the fixed electrode includes a plurality of fixed cantilever beams
  • the movable electrode includes a plurality of movable cantilever beams, the plurality of fixed cantilever beams and the plurality of movable cantilever beams are relatively spaced apart in a first direction, one end of the plurality of movable cantilever beams is fixed on a substrate, and the other ends of the plurality of movable cantilever beams are connected via connecting beams, forming a capacitor between the connecting beams and the fixed electrode.
  • the condenser microphone further includes a shell, which accommodates a substrate, a fixed electrode, and a movable electrode; the shell has a third sound conducting hole and a fourth sound conducting hole, the third sound conducting hole establishes a third acoustic path for air to flow to the surface of the movable electrode away from the fixed electrode, and the fourth sound conducting hole establishes a fourth acoustic path for air to flow to the surface of the movable electrode toward the fixed electrode.
  • the third acoustic path and the fourth acoustic path have equal path lengths.
  • the third sound guiding hole and the fourth sound guiding hole have equal opening areas.
  • the third acoustic path and the fourth acoustic path have unequal path lengths.
  • the ratio of the absolute value of the difference between the path lengths of the third acoustic path and the fourth acoustic path to the path length of the third acoustic path is not less than 10%; or, the ratio of the absolute value of the difference between the path lengths of the third acoustic path and the fourth acoustic path to the path length of the fourth acoustic path is not less than 10%.
  • an area of the third sound conducting hole is different from an area of the fourth sound conducting hole.
  • the ratio of the absolute value of the difference between the areas of the third sound guide hole and the fourth sound guide hole to the area of the third sound guide hole is not less than 10%; or, the ratio of the absolute value of the difference between the areas of the third sound guide hole and the fourth sound guide hole to the area of the fourth sound guide hole is not less than 10%.
  • acoustic resistance members corresponding to different acoustic resistance sizes are arranged at the third sound guiding hole and the fourth sound guiding hole, respectively.
  • an acoustic delay element is arranged in the third acoustic path and/or the fourth acoustic path, and the acoustic delay element is configured to extend the physical length of the corresponding acoustic path.
  • the third acoustic path and/or the fourth acoustic path each includes at least one bend.
  • FIG1 is a schematic diagram of the structure of a condenser microphone according to some embodiments of the present specification
  • 2A and 2B are diagrams showing responses of a condenser microphone under different angles between the direction of sound waves and the direction of vibration of the diaphragm according to some embodiments of this specification;
  • FIG3 is a schematic diagram of a structure in which a diaphragm and a substrate of a condenser microphone are elastically connected according to some embodiments of this specification;
  • FIG4 is a schematic structural diagram of a substrate, a back plate, and a diaphragm of a condenser microphone according to some embodiments of the present specification
  • FIG5 is a schematic structural diagram of a substrate, a back plate, and a diaphragm of a condenser microphone according to some embodiments of the present specification
  • FIG6 is a schematic structural diagram of a substrate, a back plate, and a diaphragm of a condenser microphone according to some embodiments of this specification;
  • FIG. 7 is a schematic structural diagram of a substrate, a back plate, and a diaphragm of a condenser microphone according to some embodiments of this specification;
  • FIG8 is a schematic diagram of an exemplary structure of an exemplary condenser microphone according to some embodiments of this specification.
  • FIG9 is a schematic diagram of an exemplary structure of an exemplary condenser microphone according to some embodiments of the present application.
  • FIG10 is a schematic diagram of the structure of an exemplary microphone according to some embodiments of this specification.
  • FIG11 is a schematic diagram of the structure of an exemplary microphone according to some embodiments of this specification.
  • FIG12 is a schematic diagram of the structure of an exemplary microphone according to some embodiments of this specification.
  • FIG13 is a schematic structural diagram of an exemplary first movable cantilever beam and a second movable cantilever beam according to some embodiments of the present specification
  • FIG14 is a schematic diagram of the structure of an exemplary condenser microphone according to some embodiments of this specification.
  • FIG15 is a schematic diagram of the structure of an exemplary condenser microphone according to some embodiments of this specification.
  • FIG16 is a schematic diagram of the structure of an exemplary condenser microphone according to some embodiments of this specification.
  • FIG17 is a schematic diagram of the structure of an exemplary condenser microphone according to some embodiments of this specification.
  • 18A and 18B are schematic diagrams of the structure of an exemplary condenser microphone and its acoustic path according to some embodiments of the present specification.
  • 19A and 19B are schematic diagrams of the structure of an exemplary condenser microphone and its acoustic path according to some embodiments of the present specification.
  • system means for distinguishing different components, elements, parts, portions or assemblies at different levels.
  • device means for distinguishing different components, elements, parts, portions or assemblies at different levels.
  • unit means for distinguishing different components, elements, parts, portions or assemblies at different levels.
  • the words can be replaced by other expressions.
  • the condenser microphone may include a housing, a diaphragm, and a back plate, the housing having an accommodating cavity inside, the diaphragm and the back plate being relatively spaced apart in the accommodating cavity, the side of the diaphragm facing away from the back plate forming a first cavity, the side of the back plate facing away from the diaphragm forming a second cavity, and the first cavity and the second cavity being acoustically conductive with the outside of the microphone.
  • the diaphragm and the back plate can form a capacitor, and the diaphragm and the back plate are the two poles of the capacitor, respectively.
  • the diaphragm can vibrate in response to an external sound signal (i.e., a sound wave), causing the distance between the diaphragm and the back plate to change, thereby changing the capacitance of the capacitor.
  • the change in the capacitance of the capacitor causes the amount of electricity in the capacitor to change, thereby generating an electrical signal (containing audio information).
  • a first hole array that allows airflow to pass through can be set on the diaphragm
  • a second hole array that allows airflow to pass through can be set on the back plate.
  • Sound waves propagate through the first hole array through the air. Since the flow of air molecules can generate viscosity, the diaphragm will vibrate up and down driven by the viscosity of the air molecules, and the capacitance changes accordingly, thereby realizing the conversion of sound waves into electrical signals.
  • the directions of the flow of air molecules caused by sound waves incident from different directions are different, and the directions of the viscosity generated by air molecules in different flow directions are different.
  • the amplitude (i.e., displacement) generated by the diaphragm driven by the viscosity in different directions is different.
  • the capacitance between the diaphragm and the back plate changes differently, resulting in the generated electrical signals being strong or weak, thereby realizing the direction recognition of the capacitive microphone.
  • the amplitude generated by the diaphragm is large, and the corresponding electrical signal is strong;
  • the amplitude of the diaphragm is small, almost no vibration is generated, and the corresponding electrical signal is weak.
  • the direction recognition of the capacitive microphone is realized according to the strength of the generated electrical signal.
  • the difference when there is a difference in the amplitude and/or phase of the sound waves on both sides of the diaphragm, the difference will also cause air molecules to flow along the first hole array and generate a viscous force that drives the diaphragm to vibrate.
  • the electrical signal generated by the diaphragm vibration can also reflect the difference in the sound waves transmitted to the two sides of the diaphragm, on this basis, the direction of the sound source can be identified.
  • the directional recognition of sound waves by a condenser microphone can be used for sound source localization. With the help of the directivity of the condenser microphone and the distance determination of the sound wave, the sound source localization is achieved.
  • the directional recognition of sound waves by a condenser microphone can be used for acoustic scene classification (ASC) to help identify acoustic scenes.
  • ASC acoustic scene classification
  • the directional recognition of sound waves by a condenser microphone can also be used for noise reduction calls, hearing assistance, and adaptive sound settings of devices (such as mobile phones, headphones, etc.).
  • the vibration of the diaphragm driven by the viscosity of air molecules can be applied to other types of microphones.
  • a diaphragm provided with an array of holes that allow airflow to pass through cuts the magnetic flux lines in a magnetic field and vibrates, generating an electrical signal.
  • the amplitude (i.e., displacement) of the diaphragm driven by the viscosity of air molecules in different directions is different, and accordingly, the strength of the electrical signal generated by the magnet in the magnetic field is different, thereby realizing the direction recognition of the electromagnetic microphone.
  • the rigidity of the cantilever beam or the double-ended clamped beam is relatively soft, and it can generate vibrations driven by the viscosity of air molecules.
  • FIG1 is a schematic diagram of the structure of a condenser microphone according to some embodiments of the present specification.
  • a condenser microphone 100 may include a housing 110, a diaphragm 120, and a back plate 130.
  • the housing 110 has a receiving cavity inside, and the diaphragm 120 and the back plate 130 are arranged in the receiving cavity.
  • the diaphragm 120 and the back plate 130 are arranged relatively spaced apart in the receiving cavity, and the side of the diaphragm 120 away from the back plate 130 forms a first cavity 111, and the side of the back plate 130 away from the diaphragm 120 forms a second cavity 112, and the first cavity 111 and the second cavity 112 are located on opposite sides of the diaphragm 120 and the back plate 130.
  • the housing 110 is provided with a first sound guide hole 1111 and a second sound guide hole 1121.
  • the first sound guide hole 1111 is in communication with the first cavity 111.
  • the first cavity 111 is in acoustic communication with the outside of the condenser microphone 100 through the first sound guide hole 1111.
  • the second sound guide hole 1121 is in communication with the second cavity 112.
  • the second cavity 112 is in acoustic communication with the outside of the condenser microphone 100 through the second sound guide hole 1121.
  • sound waves outside the condenser microphone 100 can enter the second cavity 112 through the second sound guide hole 1121, pass through the back plate 130 and the diaphragm 120, and then pass through the first cavity 111, and are output through the first sound guide hole 1111. In this process, the back plate 130 and the diaphragm 120 generate electrical signals accordingly.
  • sound waves outside the condenser microphone 100 can enter the first cavity 111 through the first sound guide hole 1111, and are output through the second sound guide hole 1121.
  • the housing 110 is a three-dimensional structure having an accommodating cavity (i.e., a hollow portion).
  • the housing 110 may be a regular shape such as a cuboid, a sphere, a polygon, a prism, or a structure of any irregular shape.
  • the housing 110 may be made of metal (e.g., stainless steel, copper, etc.), plastic (e.g., polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), and acrylonitrile-butadiene-styrene copolymer (ABS), etc.), composite materials (e.g., metal-based composite materials or non-metal-based composite materials), epoxy resin, phenolic, ceramic, polyimide, glass fiber (e.g., FR4-glass fiber), etc., or any combination thereof.
  • metal e.g., stainless steel, copper, etc.
  • plastic e.g., polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), and acrylonitrile-butadiene-styrene copolymer (ABS), etc.
  • composite materials e.g., metal-based composite materials or non-metal-based composite materials
  • the diaphragm 120 is a device that generates vibrations in response to sound signals.
  • the diaphragm 120 is provided with a first hole array 121 that allows airflow to pass through.
  • the first hole array 121 includes a plurality of micropores distributed in an array. Since the flow of air molecules can generate viscosity, the diaphragm 120 will vibrate up and down driven by the viscosity of the air molecules.
  • the first hole array 121 provided on the diaphragm 120 can reduce the resistance of sound waves passing through the diaphragm 120, so that the sound waves pass through the diaphragm 120 with less loss. At this time, the air viscosity has a greater impact on the diaphragm 120, and can drive the diaphragm 120 to vibrate with a larger amplitude.
  • the aperture of the micropores on the diaphragm 120 can be in the range of 5 ⁇ m-50 ⁇ m.
  • the aperture of the micropores on the diaphragm 120 is in the range of 10 ⁇ m-40 ⁇ m.
  • the aperture of the micropores on the diaphragm 120 is in the range of 15 ⁇ m-30 ⁇ m.
  • the aperture of the micropores on the diaphragm 120 is in the range of 20 ⁇ m-25 ⁇ m.
  • a sufficient number of micropores can be set on the diaphragm 120.
  • the maximum value of the hole spacing between adjacent micropores on the diaphragm 120 can be set within 50 ⁇ m.
  • the hole spacing here refers to the minimum distance between the edge of a micropore and the edge of an adjacent micropore.
  • the hole spacing between adjacent micropores on the diaphragm 120 can be in the range of 0.1 ⁇ m-50 ⁇ m.
  • the hole spacing can be in the range of 1 ⁇ m-30 ⁇ m.
  • the hole spacing can be in the range of 1 ⁇ m-20 ⁇ m.
  • the hole spacing can be in the range of 1 ⁇ m-10 ⁇ m.
  • the shape of the micro-holes may be circular, or may be a regular or irregular shape such as a quadrilateral, hexagon, or octagon.
  • the micro-holes of the first hole array 121 may be evenly distributed on the diaphragm 120.
  • the first hole array 121 may be arranged to be unevenly distributed on the diaphragm 120.
  • the apertures of the micro-holes of the first hole array 121 may be consistent.
  • the first hole array 121 in order to make different parts of the entire diaphragm 120 have consistent vibration displacement, can also be composed of micro-holes with different apertures.
  • some micropores of the first hole array 121 located in the middle of the diaphragm 120 have smaller apertures, and some micropores of the first hole array 121 located around the diaphragm 120 have larger apertures.
  • the thickness of the diaphragm 120 may be in the range of 0.1 ⁇ m-10 ⁇ m.
  • the thickness of the diaphragm 120 may be in the range of 0.1 ⁇ m-8 ⁇ m.
  • the thickness of the diaphragm 120 may be in the range of 0.1 ⁇ m-5 ⁇ m.
  • the rigidity of the diaphragm 120 may be adjusted by adjusting the thickness of the diaphragm 120, thereby adjusting the sensitivity of the condenser microphone 100.
  • the diaphragm 120 may be a thin film structure with elasticity.
  • the diaphragm 120 in order to enable the diaphragm 120 to have better elasticity and thus have a larger vibration amplitude under the action of sound waves, the diaphragm 120 may be a mesh structure formed by densely distributed filamentary structures, and the micropores on the diaphragm 120 may be tiny mesh holes on the mesh structure.
  • the diaphragm 120 may be formed of a conductive material (e.g., copper, aluminum, graphite, sputtered gold, platinum, aluminum, and other metals).
  • the diaphragm 120 may be a non-conductive polymer elastic film, and a conductive layer (e.g., an aluminum film layer) is plated on at least one side of the polymer elastic film.
  • the material of the polymer elastic film may include, but is not limited to, one or more of polyethylene terephthalate (PET), polycarbonate (PC), vinyl polymer (PVC), acrylonitrile-butadiene-styrene copolymer (ABS), polyethylene (PE), polyparaxylene (Parylene), and polyimide (PI).
  • PET polyethylene terephthalate
  • PC polycarbonate
  • PVC vinyl polymer
  • ABS acrylonitrile-butadiene-styrene copolymer
  • PE polyethylene
  • Parylene polyparaxylene
  • PI polyimide
  • the diaphragm 120 may be a composite film structure consisting of a conductive layer and a non-conductive polymer structural layer.
  • the conductive layer may include sputtered metal (e.g., gold, platinum, aluminum, and the like), and the non-conductive polymer structural layer may be made of a polymer material such as polyparaxylene (Parylene), polyimide (PI), and the like.
  • the material of the diaphragm 120 may be silicon, silicon oxide, silicon nitride, silicon carbide, a plastic material, a resin material, and the like, or any combination thereof.
  • the diaphragm 120 may be made entirely of conductive polysilicon.
  • the back plate 130 may be disposed in the housing 110, and the vibration of the diaphragm 120 relative to the back plate 130 may result in a change in the capacitance between the diaphragm 120 and the back plate 130, and a corresponding change in the generated electrical signal.
  • the back plate 130 may be disposed in the housing 110 substantially fixedly, that is, when the airflow passes through, the shape of the back plate 130 and the position relative to the housing 110 remain substantially unchanged. At this time, the change in capacitance between the diaphragm 120 and the back plate 130 mainly comes from the deformation or vibration of the diaphragm 120 under the influence of the airflow. Further optionally, the back plate 130 may vibrate relative to the housing 110 when the airflow passes through.
  • the back plate 130 and the diaphragm 120 may have different stiffnesses, forming asynchronous deformation and vibration when the airflow passes through.
  • the change in capacitance between the diaphragm 120 and the back plate 130 mainly comes from the difference in vibration between the two.
  • the difference in stiffness between the back plate 130 and the diaphragm 120 may be achieved by using different materials or different structures respectively.
  • one or more holes may be opened in the back plate 130 so that sound waves can pass through the back plate 130 through the holes on the back plate 130.
  • a second hole array 131 is provided on the back plate 130 to allow airflow to pass through, and the second hole array 131 includes a plurality of microholes distributed in an array.
  • the microholes on the second hole array 131 are similar to the microholes on the first hole array 121, and are not described in detail here.
  • the microholes on the back plate 130 correspond to the positions of the microholes on the diaphragm 120 one by one, which is conducive to the sound waves passing directly through the back plate 130 and the diaphragm 120, minimizing the loss of the sound waves.
  • "one-to-one correspondence" means that each microhole on the diaphragm 120 has a corresponding microhole on the back plate 130, and the projections of the two corresponding microholes along the vibration direction of the diaphragm 120 at least partially overlap, and the sound waves can pass through the microholes corresponding to the overlapping part.
  • the microholes on the back plate 130 correspond to the positions of the microholes on the diaphragm 120.
  • the positions of the microholes on the back plate 130 and the microholes on the diaphragm 120 correspond to each other, and the areas of the two corresponding microholes are the same, the loss of sound waves passing through the back plate 130 and the diaphragm 120 is small (negligible), the displacement of the vibration of the diaphragm 120 is the largest, and at the same time, it can ensure that there is a sufficient facing area between the back plate 130 and the diaphragm 120.
  • the back plate 130 may be disposed approximately parallel to the diaphragm 120. In some embodiments, the back plate 130 and the diaphragm 120 are spaced apart, and an air domain exists between the two. In some embodiments, after the sound wave enters the air domain through the back plate 130 or the diaphragm 120, the narrow air domain is conducive to generating a larger air viscosity, driving the diaphragm 120 to vibrate. At the same time, in order to avoid contact between the diaphragm 120 and the back plate 130 during the vibration process, the distance between the back plate 130 and the diaphragm 120 may be in the range of 0.5 ⁇ m-20 ⁇ m.
  • the distance between the back plate 130 and the diaphragm 120 may be in the range of 1 ⁇ m-15 ⁇ m.
  • the distance between the back plate 130 and the diaphragm 120 may be in the range of 2 ⁇ m-10 ⁇ m.
  • a gasket may be provided between the back plate 130 and the diaphragm 120 to separate the two.
  • a convex structure may be provided on the side of the diaphragm 120 close to the back plate 130, or a convex structure may be provided on the side of the back plate 130 close to the diaphragm 120.
  • the convex structure serves as a blocking point, which can effectively prevent the diaphragm 120 from contacting or sticking to the back plate 130.
  • the back plate 130 material may be a conductive material.
  • the back plate 130 may be formed of polysilicon and silicon nitride or any other suitable material (eg, silicon oxide, silicon, ceramic, etc.).
  • the back plate 130 and the diaphragm 120 form a parallel plate capacitor.
  • the sound waves propagate through the air through the back plate 130 or the diaphragm 120.
  • the directions of the air molecules flowing due to the sound waves incident from different directions are different.
  • the directions of the viscous forces generated by the air molecules in different flow directions are different.
  • the diaphragm 120 has different amplitudes (i.e., displacements) driven by viscous forces in different directions. Accordingly, the capacitance changes between the diaphragm 120 and the back plate 130 are different, resulting in different strengths of the generated electrical signals, thereby realizing the direction recognition of the condenser microphone 100.
  • the vibration direction of the air molecules is consistent with the propagation direction of the sound wave. Then, when the sound wave is incident vertically, the vibration direction of the air is perpendicular to the diaphragm 120, and a large speed difference can be generated between the diaphragm 120 and the diaphragm 120. The speed difference can be converted into viscous force, driving the diaphragm 120 to produce a large vibration.
  • the incident direction of the sound wave is parallel to the diaphragm 120, the vibration of the air molecules in the vertical direction of the diaphragm 120 is small, and the vibration of the diaphragm 120 is small. Therefore, the condenser microphone 100 will show very superior directionality.
  • FIG2A and FIG2B are response diagrams of the condenser microphone 100 shown in some embodiments of the present specification under different angles between the direction of the sound wave and the vibration direction of the diaphragm 120.
  • the condenser microphone 100 when the condenser microphone 100 is acted on by sound waves at angles of 90° and 270° with the vibration direction of the diaphragm 120 (i.e., the incident direction of the sound wave is parallel to the diaphragm 120), the electric signal is the weakest, i.e., the acoustic response is the worst; when the condenser microphone 100 is acted on by sound waves at angles of 0° and 180° with the vibration direction of the diaphragm 120 (i.e., the incident direction of the sound wave is perpendicular to the diaphragm 120), the electric signal is the strongest, i.e., the acoustic response is the best.
  • the condenser microphone 100 can have uniform directivity in both the 0° and 180° directions.
  • the sensitivity of the diaphragm 120 to the sound waves originating from the direction (0°) where the second sound guide hole 1121 is located can be maximized, and is basically equivalent to the sensitivity to the sound waves originating from the direction (180°) where the first sound guide hole 1111 is located.
  • the sensitivity of the diaphragm 120 to the sound waves originating from the direction perpendicular to the vibration direction (90° or 270°) is the smallest.
  • the sensitivity of the diaphragm 120 to the sound waves in different directions is in the shape of an "8".
  • the vibration of the diaphragm 120 is mainly generated by the sound source in the direction of 0° (or 180°) and its vicinity, and the diaphragm 120 mainly collects the sound originating from these directions, so that the condenser microphone 100 presents directivity.
  • the condenser microphone 100 can have stronger directivity in one of the directions of 0° and 180°.
  • the sensitivity of the diaphragm 120 to the sound waves originating from the direction (0°) where the second sound guide hole 1121 is located can be greater than the sensitivity to the sound waves originating from the direction (180°) where the first sound guide hole 1111 is located.
  • the condenser microphone 100 can better identify the sound in the direction of 0° and its vicinity.
  • the magnitude of the viscosity of the air molecules entering from the sound guide hole on the diaphragm 120 may be related to the corresponding air molecule flow rate and/or the flow path of the air molecules (e.g., acoustic path and physical path). For example, the greater the air molecule flow rate corresponding to the sound guide hole, the greater the viscosity of the air molecules on the diaphragm 120, and the more sensitive the diaphragm 120 is to the sound in the direction corresponding to the sound guide hole.
  • the directivity of the condenser microphone 100 can be controlled by controlling the flow rate of air molecules corresponding to the sound guide holes and/or the flow path of the air molecules.
  • the first sound guide hole 1111 and the second sound guide hole 1121 are controlled to have equal areas, and the corresponding flow paths of the air molecules have equal path lengths, so that the condenser microphone 100 achieves the directivity as shown in Figure 2A.
  • the first sound guide hole 1111 and the second sound guide hole 1121 having equal areas, and the corresponding flow paths of the air molecules having equal path lengths, please refer to Figure 15 and its related description, which will not be repeated here.
  • first sound guide hole 1111 and the second sound guide hole 1121 are controlled to have unequal areas, or the corresponding flow paths of the air molecules have unequal path lengths, so that the condenser microphone 100 achieves the directivity as shown in Figure 2B.
  • first sound guide hole 1111 and the second sound guide hole 1121 having unequal areas, and the corresponding flow paths of air molecules having unequal path lengths please refer to Figure 16 and its related description, which will not be repeated here.
  • the condenser microphone 100 may further include a substrate 140.
  • the substrate 140 may be a structure having an open opening, the diaphragm 120 and the back plate 130 are located at the open opening of the substrate 140 and cover the opening, and one end of the substrate 140 away from the diaphragm 120 and the back plate 130 is connected to the housing 110 to separate the accommodating cavity into a first cavity 111 and a second cavity 112 located on opposite sides of the diaphragm 120 and the back plate 130.
  • the substrate 140 may be a cylindrical structure with two ends through, one end of the cylindrical structure is connected to the housing 110, and the other end is connected to the diaphragm 120 and the back plate 130.
  • the substrate 140 may be made of a semiconductor material.
  • the semiconductor material may include, but is not limited to, silicon dioxide, silicon nitride, gallium nitride, zinc oxide, silicon carbide, and the like.
  • the back plate 130 and the diaphragm 120 can be physically connected to the substrate 140.
  • the "connection" described in this specification can be understood as the connection between different parts of the same structure, or after preparing different parts or structures separately, the independent parts or structures are fixedly connected by welding, riveting, clamping, bolting, adhesive bonding, etc., or during the preparation process, the first part or structure is deposited on the second part or structure by physical deposition (for example, physical vapor deposition) or chemical deposition (for example, chemical vapor deposition).
  • the diaphragm 120 may be rigidly or elastically connected to the substrate 140.
  • the peripheral side of the diaphragm 120 may be elastically connected to the open inner wall of the substrate 140.
  • the peripheral side of the diaphragm 120 may be rigidly connected to the open inner wall of the base 140.
  • the peripheral side of the back plate 130 may be rigidly or elastically connected to the open inner wall of the base 140.
  • the side of the back plate 130 close to the base 140 may be rigidly connected to an end of the base 140 away from the shell 110.
  • the side of the back plate 130 close to the base 140 may be elastically connected to an end of the base 140 away from the shell 110.
  • the side of the diaphragm 120 close to the base 140 may be elastically connected to an end of the base 140 away from the shell 110, and the peripheral side of the back plate 130 is rigidly connected to the open inner wall of the base 140.
  • the condenser microphone 100 may further include a processor 150.
  • the processor 150 may be configured to process data and/or signals.
  • the processor 150 may include one or more of a bipolar integrated circuit (e.g., a logic gate circuit, an emitter coupled logic circuit, etc.), a unipolar integrated circuit (e.g., a field effect transistor integrated circuit, an n-channel field effect transistor integrated circuit, etc.), and the like.
  • the processor 150 may be located in the housing cavity of the housing 110 or at least partially suspended in the housing cavity of the housing 110. In some embodiments, the processor 150 may also be located outside the housing cavity of the housing 110. For example, the processor 150 may be disposed on the outer surface of the housing 110, and may be connected to the diaphragm 120 and the back plate 130 for signal connection through the lead 160. In some embodiments, the processor 150 may process a target signal, and the processor 150 may obtain an electrical signal from the diaphragm 120 and the back plate 130 and perform signal processing.
  • the condenser microphone 100 may further include a lead 160.
  • the lead 160 may be used to connect the diaphragm 120 and the back plate 130 to the processor 150.
  • the lead 160 may transmit a target signal or other signals (such as configuration instructions, acquisition instructions, etc.).
  • the lead 160 may not be necessary, and its function may be achieved through other connection methods.
  • the diaphragm 120 and the substrate 140 may be elastically connected in a manner as shown in FIG3.
  • FIG3 is a schematic diagram of the structure of the elastic connection between the diaphragm 120 and the substrate 140 according to some embodiments of the present specification.
  • the diaphragm 120 is elastically connected to the substrate 140 through a plurality of elastic structures 122.
  • the plurality of elastic structures 122 are symmetrically distributed along the circumference of the diaphragm 120, so that the force distribution of the diaphragm 120 is uniform, thereby making the vibration consistency of the diaphragm 120 better during the vibration process.
  • the elastic structure 122 may be a folded beam structure. In some embodiments, one of the two ends of the folded beam structure is connected to the substrate 140, and the other end is fixedly connected to the diaphragm 120. In other embodiments, the elastic structure 122 may be a cantilever beam, a U-shaped beam, or other elastic beam structures. In some embodiments, the elastic structure 122 may also be an elastic structure such as a folded ring, a spring, a sponge pad, or a silicone layer.
  • the substrate 140 may be a structure that is not limited to being independent of the housing 110. In some embodiments, the substrate 140 may also be a part of the housing 110. In some other embodiments, the positions of the diaphragm 120 and the back plate 130 may be interchanged, and the side of the back plate 130 facing away from the diaphragm 120 forms the first cavity 111, and the side of the diaphragm 120 facing away from the back plate 130 forms the second cavity 112.
  • the substrate 140, the back plate 130 and the diaphragm 120 included in the condenser microphone 100 There are many ways to dispose the substrate 140, the back plate 130 and the diaphragm 120 included in the condenser microphone 100.
  • the disposition of the substrate 140, the back plate 130 and the diaphragm 120 is exemplarily described below in conjunction with FIG. 4 to FIG. 7.
  • FIG4 is a schematic diagram of the structure of the substrate 140, the back plate 130 and the diaphragm 120 of the condenser microphone 100 according to some embodiments of the present specification.
  • the back plate 130 may include an insulating layer 132 and a conductor layer 133, and the side of the insulating layer 132 close to the substrate 140 is connected to the side of the conductor layer 133 away from the substrate 140.
  • a second hole array 131 is arranged through the insulating layer 132 and the conductor layer 133, and the conductor layer 133 is between the insulating layer 132 and the diaphragm 120.
  • the diaphragm 120 is provided with a first hole array 121, and the first hole array 121 is arranged corresponding to the second hole array 131.
  • the diaphragm 120 is separated from the conductor layer by the insulating layer 141, and the insulating layer 141 forms a ring structure, which does not affect the sound waves passing through the back plate 130 and the diaphragm 120.
  • the side of the conductor layer 133 close to the substrate 140 is connected to the side of the insulating layer 141 away from the substrate 140, and the side of the insulating layer 141 close to the substrate 140 is connected to the side of the diaphragm 120 away from the substrate 140.
  • the diaphragm 120 is connected to the substrate 140 through the insulating layer 142, and the insulating layer 142 is similar to the insulating layer 141.
  • the side of the diaphragm 120 close to the substrate 140 is connected to the side of the insulating layer 142 away from the substrate 140, and the side of the insulating layer 142 close to the substrate 140 is connected to the substrate 140.
  • FIG5 is a schematic diagram of the structure of the substrate 140, the back plate 130 and the diaphragm 120 of the condenser microphone 100 according to some embodiments of the present specification.
  • the insulating layer 132 and the conductor layer 133 included in the back plate 130 shown in FIG4 can be exchanged.
  • the side of the conductor layer 133 close to the substrate 140 is connected to the side of the insulating layer 132 away from the substrate 140, and the side of the insulating layer 132 close to the substrate 140 is connected to the side of the insulating layer 141 away from the substrate 140.
  • FIG6 is a schematic diagram of the structure of the substrate 140, the back plate 130 and the diaphragm 120 of the condenser microphone 100 according to some embodiments of the present specification.
  • the back plate 130 may include an insulating layer 132 and a conductive layer 133, and the back plate 130 may exchange positions with the diaphragm 120.
  • the side of the diaphragm 120 close to the substrate 140 is connected to the side of the insulating layer 141 away from the substrate 140
  • the side of the insulating layer 141 close to the substrate 140 is connected to the side of the insulating layer 132 away from the substrate 140
  • the side of the insulating layer 132 close to the substrate 140 is connected to the side of the conductive layer 133 away from the substrate 140
  • the side of the conductive layer 133 close to the substrate 140 is connected to the insulating layer 132.
  • the side of the insulating layer 142 away from the substrate 140 is connected to the substrate 140
  • the side of the insulating layer 142 close to the substrate 140 is connected to the substrate 140 .
  • the insulating layer 132, the insulating layer 141 and the insulating layer 142 are made of the same insulating material (e.g., silicon oxide or silicon nitride).
  • the insulating layer 132 is made of silicon nitride, which has high hardness and strength, so that the back plate 130 is not easily deformed as a fixed electrode, thereby improving the reliability of the structure.
  • the conductive layer 133 can be made of conductive materials such as polysilicon or metal (e.g., copper, aluminum, etc.).
  • the number of the first sound guide holes and the second sound guide holes may be one or more. In some embodiments, the number of the first sound guide holes and the number of the second sound guide holes may be equal or unequal. For example, as shown in FIG. 1 , there may be 1 first sound guide hole 1111 and 1 second sound guide hole 1121 on the housing 110. For another example, there may be 3 first sound guide holes 1111 and 3 second sound guide holes 1121 on the housing 110. For another example, there may be 1 first sound guide hole 1111 and 2 second sound guide holes 1121 on the housing 110.
  • the shapes of the one or more first sound guide holes 1111 and the one or more second sound guide holes 1121 may be the same or different, for example, circular, rectangular, polygonal, elliptical, irregular, etc.
  • the first sound guide hole and the second sound guide hole can be respectively arranged on opposite sides of the shell.
  • the first sound guide hole 1111 and the second sound guide hole 1121 are respectively opened on the lower side and the upper side of the shell 110, the first sound guide hole 1111 is connected to the first cavity 111, the first cavity 111 is acoustically connected to the outside of the condenser microphone 100 through the first sound guide hole 1111, the second sound guide hole 1121 is connected to the second cavity 112, and the second cavity 112 is acoustically connected to the outside of the condenser microphone 100 through the second sound guide hole 1121.
  • the condenser microphone 100 is very sensitive to the direction of the sound wave injection, in order to avoid the position of the first sound guide hole 1111 and the second sound guide hole 1121 affecting the direction of the sound wave injection, the first sound guide hole 1111 and the second sound guide hole 1121 can be arranged directly opposite the diaphragm 120.
  • being arranged directly opposite to the diaphragm 120 may mean that on the plane of the back plate 130, the orthographic projection of the diaphragm 120, the orthographic projection of the first sound guide hole 1111, and the orthographic projection of the second sound guide hole 1121 at least partially overlap.
  • first sound guide hole 1111 and the second sound guide hole 1121 may be arranged directly opposite to the diaphragm 120, which can make the path of air molecules flowing from the sound guide hole to the diaphragm 120 shorter, thereby making the sound pressure attenuation of the sound wave less.
  • FIG. 14 is a schematic diagram of the structure of an exemplary condenser microphone according to some embodiments of the present specification.
  • the lower side of the shell 110 is provided with a first sound guide hole 1111a and a second sound guide hole 1121a at the same time.
  • the first sound guide hole 1111a is connected to the first cavity 111, and the first cavity 111 is acoustically connected to the outside of the condenser microphone 100 through the first sound guide hole 1111a.
  • the second sound guide hole 1121a is connected to the second cavity 112, and the second cavity 112 is acoustically connected to the outside of the condenser microphone 100 through the second sound guide hole 1121a.
  • the difference in the amplitude and/or phase of the sound pressure at the first sound guide hole 1111a and the second sound guide hole 1121a will still cause the airflow to circulate in the shell 110.
  • the condenser microphone 100 is more sensitive to the sound originating from the direction of the line connecting the two sound guide holes.
  • the first sound guide hole and the second sound guide hole can be respectively arranged on any two sides of the shell. For example, adjacent sides.
  • Figure 19B is a schematic diagram of the structure of an exemplary condenser microphone and its acoustic path according to some embodiments of this specification.
  • the lower side and the left side of the shell 110 are respectively provided with a first sound guide hole 1111d and a second sound guide hole 1121d
  • the first sound guide hole 1111d is connected to the first cavity 111
  • the first cavity 111 is acoustically connected to the outside of the condenser microphone 100 through the first sound guide hole 1111d
  • the second sound guide hole 1121d is connected to the second cavity 112
  • the second cavity 112 is acoustically connected to the outside of the condenser microphone 100 through the second sound guide hole 1121d.
  • the flow paths eg, acoustic paths and physical paths
  • the flow directions of the air molecules in the housing 110 are different.
  • the sound waves outside the condenser microphone 100 can enter the second cavity 112 through the second sound guide hole 1121, pass through the back plate 130 and the diaphragm 120, and then pass through the first cavity 111, and output through the first sound guide hole 1111. In this process, the back plate 130 and the diaphragm 120 generate electrical signals accordingly.
  • the sound waves outside the condenser microphone 100 can enter the first cavity 111 through the first sound guide hole 1111, and then output through the second sound guide hole 1121.
  • the first sound guide hole 1111 and the second sound guide hole 1121 may have equal areas.
  • the first sound guide hole 1111 and the second sound guide hole 1121 may have equal areas.
  • the areas of each first sound guide hole 1111 and each second sound guide hole 1121 may be equal, or the sum of the areas of the multiple first sound guide holes 1111 may be equal to the sum of the areas of the multiple second sound guide holes 1121.
  • the area of the first sound guide hole and/or the second sound guide hole refers to the minimum area of the cross section of the first sound guide hole and/or the second sound guide hole perpendicular to the axial direction.
  • Figure 15 is a schematic diagram of the structure of an exemplary condenser microphone according to some embodiments of this specification.
  • the first sound guide hole 1111b and the second sound guide hole 1121b can have equal areas to avoid different flow rates of air molecules in the first sound guide hole 1111b and the second sound guide hole 1121b due to their different areas, which further leads to different sensitivities of the diaphragm 120 to the flow of air molecules on both sides.
  • the area of the first sound guide hole 1111 and the area of the second sound guide hole 1121 may be different.
  • the areas of the first sound guide hole 1111 and the second sound guide hole 1121 are different, which may mean that the sum of the areas of the multiple first sound guide holes 1111 is not equal to the sum of the areas of the multiple second sound guide holes 1121.
  • Figure 16 is a schematic diagram of the structure of an exemplary condenser microphone according to some embodiments of this specification. As shown in Figure 16, the area S1 of the first sound guide hole 1111c may be smaller than the area S2 of the second sound guide hole 1121c.
  • the areas of the first sound guide hole 1111 and the second sound guide hole 1121 are different, which can make the flow of air molecules in the first sound guide hole 1111 and the second sound guide hole 1121 different, so that the sensitivity of the diaphragm 120 to the flow of air molecules in the two directions of 0° and 180° in Figures 2A and 2B is different.
  • the area S1 of the first sound guide hole 1111c is smaller than the area S2 of the second sound guide hole 1121c, so that the air molecule flow rate of the first sound guide hole 1111c is smaller than the air molecule flow rate of the second sound guide hole 1121c.
  • the viscosity F2 of the air molecules on the side of the second sound guide hole 1121c on the diaphragm 120 is greater than the viscosity F1 of the air molecules on the side of the first sound guide hole 1111c on the diaphragm 120, that is, the diaphragm 120 is more sensitive to the flow of air molecules directed to the side of the second sound guide hole 1121c, and the condenser microphone 100 can present the directivity as shown in FIG2B .
  • the directivity of the sound wave signal can be controlled by setting the area difference between the first sound guide hole and the second sound guide hole. For example, the greater the difference between the area of the second sound guide hole and the area of the first sound guide hole, the greater the intensity of the sound wave signal pointing in the direction of the second sound guide hole (0°). For another example, the area of the second sound guide hole is smaller than the area of the first sound guide hole, so that the sound wave signal points in the direction of the first sound guide hole (180°).
  • the area difference between the first sound guide hole and the second sound guide hole needs to reach a certain threshold.
  • the absolute value of the difference between the areas of the first sound guide hole 1111 and the second sound guide hole 1121 is not less than 10% of the area of the first sound guide hole 1111.
  • /S1 can be between 10% and 30%, such as 10%, 20%.
  • /S1 can be between 20% and 50%, such as 25%, 30%, 40%, etc.
  • the absolute value of the difference between the areas of the first sound guide hole 1111 and the second sound guide hole 1121 is not less than 10% of the area of the second sound guide hole 1121.
  • /S2 can be between 10% and 30%, such as 10%, 20%.
  • /S2 may be between 20% and 50%, such as 25%, 30%, 40%, etc.
  • the microphone when the microphone is required to have uniform directivity in both directions of 0° and 180° as shown in FIG. 2A , by setting the area of the first sound guide hole to be different from the area of the second sound guide hole, the intensity difference of the sound wave signal in the directions on both sides of the diaphragm caused by other factors can be adjusted.
  • the microphone when the microphone is required to have directivity in one of the directions of 0° and 180° as shown in FIG. 2B , the flow rate of air molecules can be different based on the sound guide holes of different areas, so that the viscosity of the air molecules on both sides of the diaphragm 120 on the diaphragm 120 is unequal, thereby adjusting the directivity of the sound wave signal.
  • acoustic resistance components corresponding to different acoustic resistance sizes may be arranged at the first sound guide hole and the second sound guide hole, respectively.
  • the acoustic resistance component may be an element that blocks the air from passing through the sound guide hole.
  • the acoustic component may include, but is not limited to, an acoustic resistance net, a waterproof component, and the like. The greater the acoustic resistance of the acoustic resistance component, the fewer air molecules pass through, and the smaller the amplitude of the sound wave.
  • the acoustic resistance of the acoustic component may be related to the structure and material of the acoustic resistance component.
  • Fig. 17 is a schematic diagram of an exemplary condenser microphone structure according to some embodiments of the present specification.
  • a sound resistance net 1112 with a sound resistance of R1 and a sound resistance net 1122 with a sound resistance of R2 can be respectively set at the first sound guide hole 1111 and the second sound guide hole 1121, wherein the porosity of the sound resistance net 1112 is greater than the porosity of the sound resistance net 1122, and the sound resistance R1 is less than the sound resistance R2, so the sound resistance net 1112 can allow more air to pass through the first sound guide hole 1111, and the condenser microphone 100 can present the directivity as shown in Fig. 2B.
  • the acoustic resistance of the acoustic resistor at the first sound guide hole 1111 and the second sound guide hole 1121 is different, so that the flow rate of air molecules in the first sound guide hole 1111 and the second sound guide hole 1121 is different, so that the viscosity of the air molecules on both sides of the diaphragm 120 on the diaphragm 120 is not equal, and the sensitivity of the diaphragm 120 to the flow of air molecules in the 0° and 180° directions in Figures 2A and 2B is different.
  • the directivity and direction of the sound wave signal can be controlled by setting the difference between the acoustic resistance at the first sound guide hole and the second sound guide hole. For example, the greater the difference in acoustic resistance of the acoustic resistance, the more obvious the directivity of the sound wave signal. For example, as shown in FIG2B , the intensity of the sound wave signal originating from the 0° direction is greater.
  • the acoustic path may be a path for air to flow from the sound guide hole to the diaphragm.
  • the acoustic path may be related to the relative position of the sound guide hole and the diaphragm, the shape of the housing, the relative structure and position of components in the housing, and the like.
  • the first sound guide hole can establish a first acoustic path for air to flow to the surface of the diaphragm facing away from the back plate
  • the second sound guide hole can establish a second acoustic path for air to flow to the surface of the diaphragm facing the back plate
  • the path length of the acoustic path may be the length of the actual path of the air flow.
  • the shortest path for air to flow from the first sound guide hole (or the second sound guide hole) to the diaphragm can be used as the path length of the corresponding first acoustic path (or second acoustic path).
  • the first acoustic path and the second acoustic path may have equal path lengths.
  • the path length of the first acoustic path may be the sum of the path lengths of multiple first acoustic paths corresponding to the multiple first sound guide holes 1111
  • the path length of the second acoustic path may be the sum of the path lengths of multiple second acoustic paths corresponding to the multiple second sound guide holes 1121. The longer the path length of the acoustic path, the greater the sound pressure attenuation of the external sound wave from the corresponding sound guide hole to the diaphragm 120.
  • the first acoustic path (indicated by an upward arrow in the figure) established by the first sound guide hole 1111b and the second acoustic path (indicated by a downward arrow in the figure) established by the second sound guide hole 1121b have the same path length, so that the sound pressure attenuation of the external sound wave from the first sound guide hole 1111b to the diaphragm 120 is equal to the sound pressure attenuation of the external sound wave from the second sound guide hole 1121b to the diaphragm 120, and at the same time, the phase change of the sound wave passing through the first acoustic path is equal to the phase change of the sound wave passing through the second acoustic path.
  • the sound pressure attenuation of the sound wave from the sound guide hole to the diaphragm can be regarded as the energy attenuation of the air flowing from the sound guide hole to the diaphragm.
  • the first acoustic path and the second acoustic path can have equal path lengths to avoid different energy attenuation of air molecules from the first sound guide hole 1111b to the diaphragm 120 and from the second sound guide hole 1121b to the diaphragm 120 due to the difference between the two, which further leads to different sensitivities of the diaphragm 120 to the flow of air molecules on both sides.
  • the first acoustic path and the second acoustic path may have unequal path lengths.
  • the path length L1 of the first acoustic path established by the first sound guide hole 1111c may be smaller than the path length L2 of the second acoustic path established by the second sound guide hole 1121c, so that the sound pressure attenuation of the external sound wave from the first sound guide hole 1111c to the diaphragm 120 is smaller than the sound pressure attenuation of the external sound wave from the second sound guide hole 1121c to the diaphragm 120, and at the same time, the phase change of the sound wave passing through the first acoustic path is different from the phase change of the sound wave passing through the second acoustic path, so that the viscosity F1 of the air molecules on the side of the first sound guide hole 1111
  • the difference in path length between the first acoustic path and the second acoustic path needs to reach a certain threshold.
  • the ratio of the absolute value of the difference in path length between the first acoustic path and the second acoustic path to the path length of the first acoustic path is not less than 10%.
  • /L1 can be between 10% and 30%, such as 10%, 20%.
  • /L1 can be between 20% and 50%, such as 25%, 30%, 40%, etc.
  • the ratio of the absolute value of the difference in path length between the first acoustic path and the second acoustic path to the path length of the second acoustic path is not less than 10%.
  • /L2 can be between 10% and 30%, such as 10%, 20%.
  • /L2 may be between 20% and 50%, such as 25%, 30%, 40%, etc.
  • the directivity and direction of the sound wave signal can be controlled by adjusting the difference in path length between the first acoustic path and the second acoustic path. For example, the greater the difference in path length between the first acoustic path and the second acoustic path, the more obvious the directivity of the sound collected by the microphone. For example, as shown in FIG2B , the microphone can collect more sound from the 0° direction. For another example, by making the path length of the second acoustic path smaller than the path length of the first acoustic path, the microphone can collect more sound in the direction of the second sound guide hole.
  • the path lengths of the first acoustic path and the second acoustic path can be adjusted by setting the positions of the diaphragm 120 and the back plate 130 in the housing 110. As shown in FIG15 and FIG16 , by setting the positions of the diaphragm 120 and the back plate 130 in the housing 110 to be closer to the first sound guide hole, the path length of the first acoustic path can be greater than the path length of the second acoustic path.
  • an acoustic delay element may be arranged in the first acoustic path and/or the second acoustic path to extend the physical length of the corresponding acoustic path.
  • the physical length of the acoustic path may be the length of an equivalent path of air flow.
  • the acoustic delay element may be an element that changes the phase of the sound wave. Specifically, the acoustic delay element may cause part of the sound wave to reflect or interfere, so that part of the sound wave passes through the sound guide hole after reflection or interference, thereby increasing the time for the sound wave to reach the diaphragm 120 from the sound guide hole, delaying the phase of the sound wave, which is equivalent to increasing the physical length of the acoustic path.
  • the acoustic delay element may be arranged only on the first acoustic path to increase the physical length of the first acoustic path.
  • the acoustic delay element may be arranged only on the second acoustic path to increase the physical length of the second acoustic path.
  • acoustic delay elements with different delay effects may be respectively arranged on the first acoustic path and the second acoustic path.
  • the acoustic delay element can filter impurities (e.g., water, oil, dust, other sediments, etc.) to prevent the microphone from being contaminated. In some embodiments, the acoustic delay element can reduce pressure fluctuations on the microphone caused by wind noise, impact, etc.
  • impurities e.g., water, oil, dust, other sediments, etc.
  • the acoustic delay element may be a beam structure. In some embodiments, one of the two ends of the acoustic delay element The first end or both ends may be connected to the housing 110 or the substrate 140.
  • Figures 18A and 18B are schematic diagrams of the structure of an exemplary condenser microphone and its acoustic path according to some embodiments of this specification. As shown in Figure 18A, an acoustic delay element 1113a may be arranged in the first acoustic path, and the acoustic delay element 1113a may be a cantilever beam connected to the substrate 140 at one end. During the propagation of sound waves, reflections may be generated on the cantilever beam.
  • an acoustic delay element 1113b may be arranged in the first acoustic path, and the two ends of the acoustic delay element 1113b may be connected to the two sides of the first sound guide hole 1111 on the housing 110, respectively.
  • the phase of the sound wave is delayed by the acoustic delay element 1113a (or 1113b), so that the physical length of the first acoustic path increases.
  • the intensity difference of the sound wave signal in the directions on both sides of the diaphragm caused by other factors can be adjusted by arranging the acoustic delay element in the acoustic path.
  • the directivity of the sound wave signal can also be adjusted based on the different delay effects of the acoustic delay element.
  • the directivity and direction of the sound wave signal can be controlled by adjusting the delay effect of the acoustic delay element on the phase (for example, selecting an acoustic delay element made of a material with a different reflection coefficient). For example, the better the delay effect of the acoustic delay element arranged alone on the first acoustic path, the longer the physical length of the first acoustic path, and the more obvious the directivity of the sound collected by the microphone. For example, as shown in FIG2B , the microphone can collect more sound in the 0° direction.
  • the first acoustic path and/or the second acoustic path may include at least one bending segment.
  • the bending segment may be an element that changes the propagation direction of the sound wave in the acoustic path (i.e., the direction of air flow in the acoustic path). Specifically, the bending segment changes the propagation direction of the sound wave in the acoustic path so that the sound wave cannot propagate along the original shortest acoustic path, thereby increasing the actual path length of the acoustic path of the sound wave.
  • Figures 19A and 19B are schematic diagrams of the structure of an exemplary condenser microphone and its acoustic path according to some embodiments of this specification.
  • a bending segment can be arranged only on the first acoustic path to change the propagation direction of the sound wave and increase the path length of the actual first acoustic path of the sound wave.
  • a bending segment can be arranged only on the second acoustic path to change the propagation direction of the sound wave and increase the path length of the actual second acoustic path of the sound wave.
  • bending segments of different shapes, numbers and/or positions may be provided in the first acoustic path and the second acoustic path, respectively, so that the actual path length of the first acoustic path and the actual path length of the second acoustic path are increased by different lengths.
  • one end or both ends of the plurality of bending segments may be connected to the housing 110 or the base 140 separately.
  • the bending segment 1114a and the bending segment 1114b may be baffles, one end of which is connected to different bases 140 separately.
  • one end or both ends of the plurality of bending segments may be connected to each other separately.
  • one end of the bending segment 1124a may be connected to the housing 110, the other end of the bending segment 1124a may be connected to one end of the bending segment 1124b, and the other end of the bending segment 1124b may be connected to one end of the bending segment 1124c.
  • the microphone when the microphone is required to have uniform directivity in both directions of 0° and 180° as shown in FIG. 2A, by arranging a bent end in the acoustic path, the intensity difference of the sound wave signal in the directions on both sides of the diaphragm caused by other factors can be adjusted.
  • the directivity of the sound collected by the microphone when the microphone is required to have directivity in one of the directions of 0° and 180° as shown in FIG. 2B, the directivity of the sound collected by the microphone can also be adjusted based on the different extension effects of the bent section on the acoustic path.
  • the difference in sensitivity of the two sides of the diaphragm 120 to the flow of air molecules caused by the difference in the air flux of the first sound guide hole 1111 and the air flux of the second sound guide hole 1121 can be reduced by adjusting the difference in the path length physical length between the first acoustic path and the second acoustic path.
  • the diaphragm 120 is more sensitive to the flow of air molecules pointing to the side of the second sound guide hole 1121, and the microphone is more sensitive to the sound originating from the direction (0°) of the second sound guide hole 1121.
  • the path length/physical length L1 of the first acoustic path can be adjusted to be smaller than the path length/physical length L2 of the second acoustic path, so that the sound pressure attenuation of the external sound wave from the first sound guide hole 1111 to the diaphragm 120 is smaller than the sound pressure attenuation of the external sound wave from the second sound guide hole 1121 to the diaphragm 120, so that the sensitivity of the diaphragm 120 to the flow of air molecules on both sides is the same.
  • the distance from the diaphragm 120 to the first sound guide hole can be made closer.
  • an acoustic delay element can be arranged in the second acoustic path.
  • at least one bend section can be set in the second acoustic path.
  • the difference in sensitivity of the two sides of the diaphragm 120 to the flow of air molecules caused by the difference in the path length/physical length of the first acoustic path and the second acoustic path can be reduced by adjusting the difference in the air flux of the first sound guide hole 1111 and the air flux of the second sound guide hole 1121.
  • the diaphragm 120 is more sensitive to the flow of air molecules from one side of the second sound guide hole 1121, and the microphone will collect more sound from the direction of the second sound guide hole 1121.
  • the air flux of the first sound guide hole can be adjusted to be greater than the air flux of the second sound guide hole, so that the sensitivity of the diaphragm 120 to the flow of air molecules on both sides is equal.
  • the area of the first sound guide hole 1111 may be increased or the area of the second sound guide hole 1121 may be reduced.
  • acoustic components may be arranged in the first sound guide hole 1111 and the second sound guide hole 1121, respectively, so that the acoustic resistance of the acoustic resistance component at the first sound guide hole 1111 is smaller than the acoustic resistance of the acoustic resistance component at the second sound guide hole 1121.
  • the intensity of the sound wave signal can be made directional by adjusting the difference in path length//physical length between the first acoustic path and the second acoustic path and/or adjusting the difference in air flux between the first sound guide hole 1111 and the second sound guide hole 1121.
  • the microphone of the door monitoring function needs to clearly receive the sound outside the door and try to avoid the sound inside the door from interfering with the microphone signal, so it is necessary to make the directionality of the microphone collecting sound point to the direction outside the door.
  • the air flux of the first sound guide hole in the direction inside the door can be reduced and/or the air flux of the second sound guide hole in the direction outside the door can be increased, and/or the length of the first acoustic path can be increased and/or the length of the second acoustic path can be reduced.
  • the area of the first sound guide hole can be reduced and/or the area of the second sound guide hole can be increased.
  • the acoustic resistance of the acoustic resistor at the first sound guide hole can be increased.
  • a delay element, a bending section, etc. can be set on the first acoustic path.
  • FIG. 7 is a schematic diagram of the structure of the substrate 140, the back plate 130 and the diaphragm 120 of the condenser microphone 100 according to some embodiments of the present specification.
  • the back plate 130 may include a first back plate 134 and a second back plate 135, and the first back plate 134 and the second back plate 135 may be similar to the back plate 130 shown in FIG. 4 to FIG. 6.
  • the first back plate 134 and the second back plate 135 are both provided with a second hole array 131, and the first hole array 121 on the diaphragm 120 is provided correspondingly to the second hole array 131.
  • the first back plate 134 and the second back plate 135 are connected to the substrate 140, and the diaphragm 120 is provided between the first back plate 134 and the second back plate 135.
  • the first back plate 134 and the diaphragm 120 are spaced apart to form a first capacitor
  • the second back plate 135 and the diaphragm 120 are spaced apart to form a second capacitor.
  • the diaphragm 120 vibrates under the action of sound waves, so that the capacitance values of the first capacitor and the second capacitor change.
  • the first capacitor and the second capacitor constitute a differential capacitor, and during operation, a differential signal is output.
  • the capacitance value of the first capacitor formed by the first back plate 134 and the diaphragm 120 increases, and the capacitance value of the second capacitor formed by the second back plate 135 and the diaphragm 120 decreases; when the diaphragm 120 vibrates toward the second back plate 135, the capacitance value of the first capacitor formed by the first back plate 134 and the diaphragm 120 decreases, and the capacitance value of the second capacitor formed by the second back plate 135 and the diaphragm 120 increases.
  • the differential signal between the first capacitor and the second capacitor increases, so the sensitivity and signal-to-noise ratio of the condenser microphone 100 can be improved.
  • FIG8 is a schematic diagram of an exemplary structure of an exemplary condenser microphone 800 according to some embodiments of the present specification.
  • the condenser microphone 800 may include a housing 810, a fixed electrode 820, a movable electrode 830, and a substrate 840.
  • the housing 810 has a receiving cavity inside, and the fixed electrode 820, the movable electrode 830, and the substrate 840 are arranged in the receiving cavity.
  • the fixed electrode 820 and the movable electrode 830 are arranged in a relative spacing in the first direction in the receiving cavity to form a capacitor.
  • the fixed electrode 820 is fixed on the substrate 840 substantially immovably, the movable electrode 830 is mounted on the substrate 840, and at least a portion of the movable electrode 830 is configured to vibrate along the second direction.
  • the second direction may be perpendicular to the first direction.
  • the vibration of the movable electrode 830 relative to the fixed electrode 820 may change the area of the fixed electrode 820 and the movable electrode 830 facing each other along the first direction to produce a change in capacitance.
  • the area of the fixed electrode 820 and the movable electrode 830 facing each other refers to the overlapping area of the two opposite surfaces of the fixed electrode 820 and the movable electrode 830 projected along the first direction.
  • the movable electrode 830 may be a beam structure with a single end fixed or a double end fixed.
  • the movable electrode 830 when the movable electrode 830 is a beam structure with a single end fixed, one end that is not fixed is suspended and can vibrate along the second direction; when the movable electrode 830 is a beam structure with a double end fixed, the suspended portion between the two fixed ends can vibrate along the second direction.
  • the material of the fixed electrode 820 and/or the movable electrode 830 may be similar to the material of the diaphragm 120 , which will not be described in detail herein.
  • the housing 810 is provided with a third sound guide hole 8111 and a fourth sound guide hole 8121 respectively arranged on both sides of the fixed electrode 820 and the movable electrode 830 along the second direction.
  • the sound waves outside the condenser microphone 800 can enter the housing 810 through the fourth sound guide hole 8121, and drive the movable electrode 830 to vibrate along the second direction, and after passing through the gap between the fixed electrode 820 and the movable electrode 830, they are output along the third sound guide hole 8111.
  • the fixed electrode 820 and the movable electrode 830 respond to generate an electrical signal.
  • the sound waves outside the condenser microphone 800 can enter the housing 810 through the third sound guide hole 8111, and drive the movable electrode 830 to vibrate along the second direction, and after passing through the gap between the fixed electrode 820 and the movable electrode 830, they are output along the fourth sound guide hole 8121.
  • the housing 810 may have similar structural materials as the housing 110 shown in FIG. 1, and the substrate 840 may have similar structural materials as the substrate 140 shown in FIG. 1, which are not described in detail here.
  • the condenser microphone 800 may also include a processor 150 and/or a lead 160 as shown in FIG. 1, which are not described in detail here.
  • the fixed electrode 820 and the movable electrode 830 form a parallel plate capacitor.
  • the directions of the air molecules caused by the sound waves incident from different directions are different.
  • the air molecules with different flow directions make the vibration amplitude (i.e., displacement) of the movable electrode 830 along the second direction different. Accordingly, the facing area between the movable electrode 830 and the fixed electrode 820 is different, thereby generating different capacitances, resulting in the generated electrical signals having different strengths, thereby realizing the direction recognition of the condenser microphone 100.
  • the condenser microphone 800 When the sound wave is incident from the second direction When the sound wave is incident from the first direction, the air molecules vibrate in the second direction, driving the movable electrode 830 to generate a larger vibration in the second direction. When the sound wave is incident from the first direction, the vibration of the air molecules in the second direction is smaller, and the vibration of the movable electrode 830 in the second direction is smaller. Therefore, the condenser microphone 800 will show excellent directivity.
  • the condenser microphone 800 is very sensitive to the direction of the sound wave injection, in order to avoid the positions of the third sound guide hole 8111 and the fourth sound guide hole 8121 affecting the direction of the sound wave injection, the third sound guide hole 8111 and the fourth sound guide hole 8121 can be set opposite to the interval between the fixed electrode 820 and the movable electrode 830.
  • the structure of the fixed electrode 820 and/or the movable electrode 830 may have different variations.
  • the fixed electrode 820 and/or the movable electrode 830 may be an integral electrode.
  • the fixed electrode 820 and/or the movable electrode 830 may include a plurality of sub-electrodes.
  • FIG. 9 is a schematic diagram of an exemplary structure of an exemplary capacitive microphone 800 according to some embodiments of the present application. As shown in FIG. 9 , the fixed electrode 820 may include a plurality of first electrodes 821 arranged at intervals along the first direction, and the movable electrode 830 may include a plurality of second electrodes 831 arranged at intervals along the first direction.
  • the gap between any first electrode 821 in the fixed electrode 820 and the second electrode 831 adjacent to the first electrode 821 on the movable electrode 830 may be within a range of 5 ⁇ m-50 ⁇ m along the first direction.
  • the distance of the gap between each first electrode 821 and the adjacent second electrode 831 along the first direction may be in the range of 10 ⁇ m-40 ⁇ m.
  • the distance of the gap between each first electrode 821 and the adjacent second electrode 831 along the first direction may be in the range of 15 ⁇ m-30 ⁇ m.
  • the distance of the gap between each first electrode 821 and the adjacent second electrode 831 along the first direction may be in the range of 20 ⁇ m-25 ⁇ m.
  • the distance of the gap between each first electrode 821 and the adjacent second electrode 831 along the first direction may be the same. In some embodiments, in order to enable different parts of the entire movable electrode 830 to have consistent vibration displacement, the distance of the gap between the first electrode 821 and the adjacent second electrode 831 along the first direction may be different.
  • the distance of the gap between the adjacent first electrode 821 and the second electrode 831 at the peripheral position close to the substrate 840 along the first direction may be smaller than the distance of the gap between the adjacent first electrode 821 and the second electrode 831 at the central position away from the substrate 840 along the first direction.
  • the plurality of first electrodes 821 may be fixed substantially immovably on the substrate 840.
  • the plurality of second electrodes 831 may be beam structures fixed at one end or at two ends. For example, one end or both ends of each second electrode 831 may be fixed on the substrate 840 so that the second electrode 831 can vibrate along the second direction.
  • each first electrode 821 in the fixed electrode 820 may include a plurality of sub-electrode layers spaced apart along the second direction, and each two adjacent sub-electrode layers are separated by a sub-insulating layer. As shown in FIG8 , each first electrode 821 in the fixed electrode 820 may include a first sub-electrode layer 8211, a first sub-insulating layer 8212, a second sub-electrode layer 8213, a second sub-insulating layer 8214, and a third sub-electrode layer 8215, which are respectively distributed along the second direction.
  • the second electrode 831 when any second electrode 831 in the movable electrode 830 moves along the second direction, the second electrode 831 forms a first sub-capacitor with the first sub-electrode layer 8211, the second electrode 831 forms a second sub-capacitor with the second sub-electrode layer 8213, and the second electrode 831 forms a third sub-capacitor with the third sub-electrode layer 8215.
  • the second electrode 831 vibrates under the action of sound waves, thereby causing the capacitance values of the first sub-capacitor, the second sub-capacitor, and the third sub-capacitor to change.
  • a differential capacitor may be formed between any two sub-capacitors.
  • the first sub-capacitor and the second sub-capacitor form a differential capacitor, and during operation, a differential signal is output.
  • the capacitance value of the first sub-capacitor formed by the second electrode 831 and the first sub-electrode layer 8211 increases, and the capacitance value of the second sub-capacitor formed by the second electrode 831 and the second sub-electrode layer 8213 decreases.
  • the differential signal between the first sub-capacitor and the second sub-capacitor increases, thereby improving the sensitivity and signal-to-noise ratio of the condenser microphone 800.
  • FIG. 10 is a schematic diagram of the structure of an exemplary microphone 1000 according to some embodiments of the present specification.
  • the microphone 1000 shown in FIG. 10 may be a capacitive microphone as described in FIG. 8-FIG. 9 of the present specification, or may be another type of microphone (e.g., a piezoelectric microphone, a piezoresistive microphone, etc.).
  • the microphone 1000 may include a substrate 1040, a fixed electrode 1020, and a movable electrode 1030.
  • the material of the movable electrode 1030 may include a relatively soft material such as plastic or resin.
  • the movable electrode 1030 in order to increase the flexibility of the movable electrode 1030 and thereby increase the amplitude of the vibration of the movable electrode 1030 (i.e., the displacement of the vibration in the direction perpendicular to the paper), the movable electrode 1030 may be an electrode with a curved structure. As shown in FIG. 10 , the movable electrode 1030 may be an electrode with a serpentine structure.
  • the serpentine structure electrode shown in FIG10 is only an example, and the bending structure of the movable electrode 1030 can be other structures that can increase the extension length of the movable electrode 1030, for example, S-shaped, W-shaped, V-shaped, U-shaped, etc.
  • the number of bending units in the bending structure can be in the range of 1-10.
  • "bending unit” refers to the connecting portion between adjacent parts extending in different directions in the bending structure.
  • the two fixed ends of the bending structure can be on both sides of the substrate 1040 along the third direction (as shown in FIG. 10 ), or on the same side of the substrate 1040 along the third direction.
  • the ratio of the total length of the bending structure to the distance between the two fixed ends along the third direction is greater than 1.
  • the fixed end of the bending structure can be on any side of the substrate 1040 along the third direction.
  • the width of the bending structure can be in the range of 0.1 ⁇ m-30 ⁇ m, and the thickness can be in the range of 0.1 ⁇ m-30 ⁇ m.
  • the spacing between the movable electrode 1030 and the fixed electrode 1020 in the plane defined by the first direction and the third direction may be in the range of 5 ⁇ m-50 ⁇ m.
  • the spacing between any two adjacent parts of the movable electrode 1030 and the fixed electrode 1020 in the plane defined by the first direction and the third direction may be in the range of 5 ⁇ m-50 ⁇ m.
  • FIG. 11 is a schematic diagram of the structure of an exemplary microphone 1000 according to some embodiments of the present specification.
  • the microphone 1000 shown in FIG. 11 may be a capacitive microphone as described in FIG. 8-FIG. 9 of the present specification, or may be other types of microphones (e.g., a piezoelectric microphone, a piezoresistive microphone, etc.).
  • the microphone 1000 may include a substrate 1040, a fixed electrode 1020, and a movable electrode 1030.
  • the fixed electrode 1020 may include a plurality of fixed cantilever beams 1021. In some embodiments, the fixed cantilever beams 1021 may be fixed substantially immovably on the substrate 1040.
  • the movable electrode 1030 may include a plurality of movable cantilever beams 1031 and a connecting beam 1032.
  • the plurality of fixed cantilever beams 1021 and the plurality of movable cantilever beams 1031 are arranged to be spaced apart from each other in a first direction to form a capacitor.
  • one end of the plurality of movable cantilever beams 1031 is fixed on the substrate 1040, and the other ends (free ends, i.e., non-fixed ends) are connected by connecting beams 1032. Since the part with the largest amplitude on each movable cantilever beam 1031 is the free end, the free ends of multiple movable cantilever beams 1031 are connected by a connecting beam 1032.
  • the amplitude at the connecting beam 1032 is the largest. Therefore, compared with the case where there is no connecting beam 1032 at the free end, the free ends of multiple movable cantilever beams 1031 are connected by the connecting beam 1032, which increases the capacitance formed between the connecting beam 1032 and the fixed electrode 1020 (that is, multiple fixed cantilever beams 1021), thereby improving the sensitivity of the microphone 1000.
  • the material of the connecting beam 1032 may be different from the material of the multiple movable cantilever beams 1031.
  • the elastic modulus of the material of the connecting beam 1032 may be smaller than the elastic modulus of the material of the multiple movable cantilever beams 1031, so as to increase the amplitude at the connecting beam 1032, increase the capacitance formed between the connecting beam 1032 and the fixed electrode 102, and improve the sensitivity of the microphone 1000.
  • the material of the connecting beam 1032 in order to facilitate the preparation of the movable electrode 1030, the material of the connecting beam 1032 may be the same as the material of the multiple movable cantilever beams 1031.
  • the material of the connecting beam 1032 may be the same as the material of the multiple movable cantilever beams 1031, and may be made by integral molding.
  • the width of the movable cantilever beam 1031 and/or the connecting beam 1032 may be in the range of 0.1 ⁇ m-30 ⁇ m, and the thickness of the movable cantilever beam 1031 and/or the connecting beam 1032 may be in the range of 0.1 ⁇ m-30 ⁇ m.
  • the width of the movable cantilever beam 1031 may be the same as the width of the connecting beam 1032.
  • the spacing between the movable electrode 1030 (e.g., the movable cantilever beam 1031 and/or the connecting beam 1032) and the fixed electrode 1020 in the paper plane may be in the range of 5 ⁇ m-50 ⁇ m.
  • the spacing between any two adjacent parts of the movable electrode 1030 (e.g., the movable cantilever beam 1031 and/or the connecting beam 1032) and the fixed electrode 1020 in the plane of the paper may be in the range of 5 ⁇ m-50 ⁇ m.
  • the spacing between the movable cantilever beam 1031 and the fixed electrode 1020 in the plane of the paper is the same as the spacing between the connecting beam 1032 and the fixed electrode 1020 in the plane of the paper.
  • the first movable electrode 1120 may include a plurality of first movable cantilever beams 1121 fixed at one end.
  • the second movable electrode 1130 may include a plurality of second movable cantilever beams 1131 fixed at one end.
  • the plurality of first movable cantilever beams 1121 and the plurality of second movable cantilever beams 1131 are relatively spaced apart in a first direction to form a capacitor.
  • FIG13 is a schematic diagram of the structure of an exemplary first movable cantilever beam 1121 and a second movable cantilever beam 1131 according to some embodiments of the present specification. As shown in FIGS.
  • the fixed ends 11210 of the plurality of first movable cantilever beams 1121 and the free ends 11211 of the plurality of first movable cantilever beams 1121 are located at opposite ends of the plurality of first movable cantilever beams 1121 in a third direction.
  • the free ends 11311 of the plurality of second movable cantilever beams 1131 and the fixed ends 11310 of the plurality of second movable cantilever beams 1131 are located at opposite ends of the plurality of second movable cantilever beams 1131 in the third direction.
  • the plurality of first movable cantilever beams 1121 and the plurality of second movable cantilever beams 1131 are arranged adjacent to and spaced apart from each other in the first direction.
  • the fixed ends 11210 of the plurality of first movable cantilever beams 1121 and the free ends 11311 of the plurality of second movable cantilever beams 1131 are arranged adjacent to each other in sequence along the first direction; the free ends 11211 of the plurality of first movable cantilever beams 1121 and the fixed ends 11310 of the plurality of second movable cantilever beams 1131 are arranged adjacent to each other in sequence along the first direction. Since the maximum displacement of each first movable cantilever beam 1121 and each second movable cantilever beam 1131 is concentrated at the free end (i.e.
  • the first movable cantilever beam 1120 has a non-fixed end, while the displacement of the fixed end is very small. Therefore, the plurality of first movable cantilever beams 1121 and the plurality of second movable cantilever beams 1131 are arranged at intervals, so that the free end 11211 of each first movable cantilever beam 1121 and the fixed end 11310 of the adjacent second movable cantilever beam 1131 form a first capacitor, and the fixed end 11210 of each first movable cantilever beam 1121 and the free end 11311 of the adjacent second movable cantilever beam 1131 form a second capacitor. During the vibration of the first movable electrode 1120 and the second movable electrode 1130, the plurality of first capacitors and the plurality of second capacitors are connected in parallel, thereby improving the sensitivity of the microphone 1000.
  • the width of the first movable electrode 1120 and the second movable electrode 1130 may be in the range of 0.1 ⁇ m-30 ⁇ m, and the thickness may be in the range of 0.1 ⁇ m-30 ⁇ m.
  • the third sound guide hole 8111 and the fourth sound guide hole 8121 can have equal opening areas, thereby avoiding the different flow rates of air molecules through the third sound guide hole 8111 and the fourth sound guide hole 8121 due to the different areas between the two, which further leads to different sensitivities of the diaphragm 120 to the flow of air molecules on both sides.
  • the area of the third sound guide hole and the area of the fourth sound guide hole may be different.
  • the ratio of the absolute value of the difference between the areas of the third sound guide hole and the fourth sound guide hole to the area of the third sound guide hole may be no less than 10%. In some embodiments, the ratio of the absolute value of the difference between the areas of the third sound guide hole and the fourth sound guide hole to the area of the fourth sound guide hole may be no less than 10%.
  • acoustic resistance members corresponding to different acoustic resistance sizes may be arranged at the third sound guide hole 8111 and the fourth sound guide hole 8121, respectively.
  • the third sound guide hole 8111 can establish a third acoustic path for air to flow to the surface of the movable electrode facing away from the fixed electrode
  • the fourth sound guide hole 8121 can establish a fourth acoustic path for air to flow to the surface of the movable electrode facing the fixed electrode.
  • the third acoustic path and the fourth acoustic path can have equal path lengths, thereby avoiding the different energy attenuation of air molecules from the third sound guide hole 8111 to the diaphragm 120 and the different energy attenuation from the fourth sound guide hole 8121 to the diaphragm 120 due to the difference between the two, which further leads to different sensitivities of the diaphragm 120 to the flow of air molecules on both sides.
  • the third acoustic path and the fourth acoustic path may have unequal path lengths.
  • the ratio of the absolute value of the difference between the path lengths of the third acoustic path and the fourth acoustic path to the path length of the third acoustic path may be no less than 10%.
  • the ratio of the absolute value of the difference between the path lengths of the third acoustic path and the fourth acoustic path to the path length of the fourth acoustic path may be no less than 10%.
  • an acoustic delay element may be arranged in the third acoustic path and/or the fourth acoustic path, and the acoustic delay element is configured to extend the physical length of the corresponding acoustic path.
  • the third acoustic path and/or the fourth acoustic path may include at least one bend segment.
  • the beneficial effects that may be brought about by the embodiments of this specification include but are not limited to: (1) by designing microporous structures on the back plate and the diaphragm, the diaphragm generates different vibrations under sound signals in different directions, so that the condenser microphone has directionality; (2) by designing the aperture of the micropores, the hole spacing between adjacent micropores, etc., the sound wave loss can be reduced through the diaphragm, so as to improve the sensitivity of the condenser microphone; (3) by designing the distance between the back plate and the diaphragm or providing a protruding structure between the back plate and the diaphragm, the diaphragm is prevented from contacting the back plate during the vibration process; (4) by designing the elastic structure between the diaphragm and the substrate, the connection between the substrate and the diaphragm is prevented from affecting the vibration of the diaphragm; (5) by designing two back plates and the diaphragm to form two capacitors, the sensitivity and signal-to-
  • Figures 1 to 13 are only used for exemplary descriptions and do not constitute a limitation thereto.
  • various changes and modifications may be made according to the guidance of this application.
  • Different embodiments may produce different beneficial effects.
  • the beneficial effects that may be produced may be any one or a combination of the above, or any other beneficial effects that may be obtained.
  • the present application uses specific words to describe the embodiments of the present application.
  • “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 application. Therefore, it should be emphasized and noted that “one embodiment” or “an embodiment” or “an alternative embodiment” mentioned twice or more in different positions in this specification does not necessarily refer to the same embodiment.
  • some features, structures or characteristics in one or more embodiments of the present application can be appropriately combined.
  • numbers describing the number of components and attributes are used. It should be understood that such numbers used in the description of the embodiments are modified by the modifiers "about”, “approximately” or “substantially” in some examples. Unless otherwise specified, “about”, “approximately” or “substantially” indicate that the numbers are allowed to vary by ⁇ 20%. Accordingly, in some embodiments, the numerical parameters used in the specification and claims are approximate values, which may change according to the required features of individual embodiments. In some embodiments, the numerical parameters should take into account the specified significant digits and adopt the general method of retaining digits. Although the numerical domains and parameters used to confirm the breadth of their range in some embodiments of the present application are approximate values, in specific embodiments, the setting of such numerical values is as accurate as possible within the feasible range.

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Abstract

一种电容式麦克风（100，800，1000），包括振膜（120），振膜（120）上设置允许气流通过的第一孔阵（121）；以及背板（130），背板（130）上设置允许气流通过的第二孔阵（131），振膜（120）和背板（130）相对隔开设置以形成电容。

Description

麦克风
交叉引用
本申请要求于2023年05月10日提交的中国申请号202310532440.0的中国发明申请的优先权，其内容通过引用结合于此。
技术领域
本说明书涉及声学领域，特别涉及一种在空气分子粘滞力作用下进行声电转换的麦克风。
背景技术
随着消费电子的不断升级，指向性麦克风的需求越来越大，在场景识别、声源定位、降噪通话、听力辅助等方面均有巨大的潜在应用。因此，希望提供一种可以调整方向性的麦克风。
发明内容
本说明书实施例之一提供一种电容式麦克风，包括振膜，振膜上设置允许气流通过的第一孔阵；以及背板，背板上设置允许气流通过的第二孔阵，振膜和背板相对隔开设置以形成电容。
在一些实施例中，振膜上第一孔阵中每个孔的孔径在5μm-50μm范围内；或背板上第二孔阵中每个孔的孔径在5μm-50μm范围内。
在一些实施例中，振膜上第一孔阵中两个相邻孔之间的间距在0.1μm-50μm范围内；或背板上第二孔阵中两个相邻孔之间的间距在0.1μm-50μm范围内。
在一些实施例中，背板与振膜之间的距离在0.5μm-20μm范围内。
在一些实施例中，振膜与背板上的孔的位置一一对应。
在一些实施例中，还包括基底，振膜的周侧与基底弹性连接。
在一些实施例中，振膜的周侧通过多个对称分布的弹性结构与基底弹性连接。
在一些实施例中，背板的周侧与基底刚性连接。
在一些实施例中，背板朝向振膜的表面或振膜朝向背板的表面上设置有凸起结构。
在一些实施例中，背板包括导体层和绝缘层，导体层在绝缘层和振膜之间。
在一些实施例中，背板包括导体层和绝缘层，绝缘层在导体层和振膜之间。
在一些实施例中，振膜的材料包括以下材料至少之一：多晶硅、聚对二甲苯、聚酰亚胺或金属。
在一些实施例中，背板包括第一背板和第二背板，第一背板与第二背板分别设置于振膜的两侧，振膜和第一背板相对隔开设置以形成第一电容，振膜与第二背板相对隔开设置以形成第二电容。
在一些实施例中，振膜的厚度在0.1μm-10μm范围内。
在一些实施例中，绝缘层的材料为氧化硅或氮化硅，导电层的材料为多晶硅或者金属。
在一些实施例中，第一孔阵在振膜上不均匀分布。
在一些实施例中，电容式麦克风还包括容纳振膜和背板的壳体，壳体上具有第一导声孔和第二导声孔，第一导声孔建立让空气流动到振膜背离背板的表面的第一声学路径，第二导声孔建立让空气流动到振膜朝向背板的表面的第二声学路径。
在一些实施例中，第一声学路径和第二声学路径具有相等的路径长度。
在一些实施例中，第一导声孔和第二导声孔具有相等的开口面积。
在一些实施例中，第一声学路径和第二声学路径具有不相等的路径长度。
在一些实施例中，第一声学路径和第二声学路径的路径长度之差的绝对值与第一声学路径的路径长度之比不小于10％；或者，第一声学路径和第二声学路径的路径长度之差的绝对值与第二声学路径的路径长度之比不小于10％。
在一些实施例中，第一导声孔的面积与第二导声孔的面积不同。
在一些实施例中，第一导声孔与第二导声孔的面积之差的绝对值与第一导声孔的面积之比不小于10％；或者，第一导声孔与第二导声孔的面积之差的绝对值与第二导声孔的面积之比不小于10％。
在一些实施例中，第一导声孔处和第二导声孔处分别布置有对应于不同声阻大小的声阻件。
在一些实施例中，第一声学路径和/或第二声学路径中布置声延迟元件，声延迟元件被配置为延长对应声学路径的物理长度。
在一些实施例中，第一声学路径和/或第二声学路径均包括至少一个弯折段。
本说明书实施例还提供一种电容式麦克风，包括基底；固定电极，固定电极固定在基底上；以及可移动电极，可移动电极固定在基底上，固定电极与可移动电极在第一方向上相对隔开设置以形成电容，可移动电极被配置为沿着垂直于第一方向的第二方向振动，振动改变固定电极和可移动电极沿第一方向的正对面积。
在一些实施例中，固定电极包括沿第一方向上间隔排布的多个第一电极，可移动电极包括沿第一方向上间隔分布的多个第二电极。
在一些实施例中，可移动电极的一端固定在基底上。
在一些实施例中，可移动电极的两端固定在基底上。
在一些实施例中，可移动电极具有弯曲结构。
在一些实施例中，弯曲结构的宽度在0.1μm-30μm范围内。
在一些实施例中，弯曲结构的厚度在0.1μm-30μm范围内。
在一些实施例中，固定电极包括沿着第二方向分布的多个子电极层，每两个相邻的子电极层之间通过子绝缘层隔开。
在一些实施例中，固定电极包括多个固定悬臂梁；可移动电极包括多个可动悬臂梁，多个固定悬臂梁与多个可动悬臂梁在第一方向上相对隔开设置，多个可动悬臂梁的一端固定在基底上，多个可动悬臂梁的另外一端通过连接梁连接，连接梁与固定电极之间形成的电容。
在一些实施例中，电容式麦克风还包括壳体，壳体容纳基底、固定电极和可移动电极；壳体上具有第三导声孔和第四导声孔，第三导声孔建立让空气流动到可移动电极背离固定电极的表面的第三声学路径，第四导声孔建立让空气流动到可移动电极朝向固定电极的表面的第四声学路径。
在一些实施例中，第三声学路径和第四声学路径具有相等的路径长度。
在一些实施例中，第三导声孔和第四导声孔具有相等的开口面积。
在一些实施例中，第三声学路径和第四声学路径具有不相等的路径长度。
在一些实施例中，第三声学路径和第四声学路径的路径长度之差的绝对值与第三声学路径的路径长度之比不小于10％；或者，第三声学路径和第四声学路径的路径长度之差的绝对值与第四声学路径的路径长度之比不小于10％。
在一些实施例中，第三导声孔的面积与第四导声孔的面积不同。
在一些实施例中，第三导声孔与第四导声孔的面积之差的绝对值与第三导声孔的面积之比不小于10％；或者，第三导声孔与第四导声孔的面积之差的绝对值与第四导声孔的面积之比不小于10％。
在一些实施例中，第三导声孔处和第四导声孔处分别布置有对应于不同声阻大小的声阻件。
在一些实施例中，第三声学路径和/或第四声学路径中布置声延迟元件，声延迟元件被配置为延长对应声学路径的物理长度。
在一些实施例中，第三声学路径和/或第四声学路径均包括至少一个弯折段。
附图说明
图1是根据本说明书一些实施例所示的电容式麦克风的结构示意图；
图2A和图2B是根据本说明书一些实施例所示的电容式麦克风在声波方向与振膜振动方向的不同夹角的作用下的响应示图；
图3是根据本说明书一些实施例所示的电容式麦克风的振膜与基底弹性连接的结构示意图；
图4是根据本说明书一些实施例所示的电容式麦克风的基底、背板及振膜的结构示意图；
图5是根据本说明书一些实施例所示的电容式麦克风的基底、背板及振膜的结构示意图；
图6是根据本说明书一些实施例所示的电容式麦克风的基底、背板及振膜的结构示意图；
图7是根据本说明书一些实施例所示的电容式麦克风的基底、背板及振膜的结构示意图；
图8是根据本说明书一些实施例所示的示例性电容式麦克风的示例性结构示意图；
图9是根据本申请一些实施例所示的示例性电容式麦克风的示例性结构示意图；
图10是根据本说明书一些实施例所示的示例性麦克风的结构示意图；
图11是根据本说明书一些实施例所示的示例性麦克风的结构示意图；
图12是根据本说明书一些实施例所示的示例性麦克风的结构示意图；
图13是根据本说明书一些实施例所示的示例性第一可动悬臂梁和第二可动悬臂梁的结构示意图；
图14是根据本说明书一些实施例所示的示例性的电容式麦克风的结构示意图；
图15是根据本说明书一些实施例所示的示例性的电容式麦克风的结构示意图；
图16是根据本说明书一些实施例所示的示例性的电容式麦克风的结构示意图；
图17是根据本说明书一些实施例所示的示例性的电容式麦克风的结构示意图；
图18A和图18B是根据本说明书一些实施例所示的示例性的电容式麦克风的结构及其声学路径的示意图；以及
图19A和图19B是根据本说明书一些实施例所示的示例性的电容式麦克风的结构及其声学路径的示意图。
具体实施方式
为了更清楚地说明本申请实施例的技术方案，下面将对实施例描述中所需要使用的附图作简单的介绍。显而易见地，下面描述中的附图仅仅是本申请的一些示例或实施例，对于本领域的普通技术人员来讲，在不付出创造性劳动的前提下，还可以根据这些附图将本申请应用于其它类似情景。除非从语言环境中显而易见或另做说明，图中相同标号代表相同结构或操作。
应当理解，本文使用的“系统”、“装置”、“单元”和/或“模块”是用于区分不同级别的不同组件、元件、部件、部分或装配的一种方法。然而，如果其他词语可实现相同的目的，则可通过其他表达来替换词语。
如本申请和权利要求书中所示，除非上下文明确提示例外情形，“一”、“一个”、“一种”和/或“该”等词并非特指单数，也可包括复数。一般说来，术语“包括”与“包含”仅提示包括已明确标识的步骤和元素，而这些步骤和元素不构成一个排它性的罗列，方法或者设备也可能包含其它的步骤或元素。
本说明书实施例描述了一种电容式麦克风。在一些实施例中，电容式麦克风可以包括壳体、振膜和背板，壳体内部具有容置腔，振膜和背板在容置腔内相对间隔设置，振膜背离背板的一侧形成第一腔体，背板背离振膜的一侧形成第二腔体，第一腔体及第二腔体与麦克风外部声学导通。振膜和背板能够构成电容器，振膜和背板分别为该电容器的两极。振膜可以响应于外部声音信号(即声波)产生振动，导致振膜与背板之间的距离会发生改变，从而改变了电容器的电容。电容器的电容变化使电容器内的电量发生变化，从而产生电信号(包含音频信息)。
在一些实施例中，振膜上可以设置允许气流通过的第一孔阵，背板上设置允许气流通过的第二孔阵。声波经空气传播通过第一孔阵，由于空气分子的流动能够产生粘滞力，振膜会在空气分子粘滞力的带动下上下振动，电容随之改变，由此实现声波转化为电信号。由不同方向入射的声波导致的空气分子流动的方向不同，不同流动方向的空气分子产生的粘滞力方向不同，振膜在不同方向的粘滞力带动下产生的振幅(即位移)不同，相应地，振膜与背板之间的电容变化不同，导致产生的电信号有强弱之分，由此可以实现电容式麦克风的方向识别。例如，当声波沿垂直于振膜的方向传播，使振膜产生的振幅大，相应电信号强；当声波沿平行于振膜的方向传播，使振膜的振幅小，接近几乎不产生振动，相应电信号弱，根据产生的电信号强弱实现电容式麦克风的方向识别。此外，当振膜两侧声波的幅值和/或相位存在差异时，该差异也会导致空气分子沿着第一孔阵流动并产生带动振膜振动的粘滞力。在这种情况下，振膜振动产生的电信号也能够反映出传递到振膜两侧的声波的差异，在此基础上可以实现对声源方向的识别。
在一些实施例中，电容式麦克风对于声波的方向识别可以用于声源定位，借助电容式麦克风的指向性，配合声波的距离确定，实现声源定位。在一些实施例中，电容式麦克风对于声波的方向识别可以用于声学场景分类(ASC)，帮助进行声学场景的识别。在一些实施例中，电容式麦克风对于声波的方向识别还可以用于降噪通话、听力辅助、设备(例如手机、耳机等)自适应声音设置等方面。
应当理解的是，空气分子粘滞力的带动振膜产生振动可以应用于其他类型的麦克风。例如，在电磁式麦克风中，设置有允许气流通过的孔阵的振膜在磁场中切割磁感线振动，并产生电信号。振膜在不同方向的空气分子粘滞力带动下产生的振幅(即位移)不同，相应地，磁场中的磁铁产生的电信号强弱不同，由此可以实现电磁式麦克风的方向识别。再例如，在压电式或压阻式麦克风中，当悬臂梁或双端固支梁足够长时，悬臂梁或双端固支梁的刚性较软，可以在空气分子的粘滞力带动下产生振动。
下面将结合附图对本说明书实施例提供的电容式麦克风进行示例性说明。
图1是根据本说明书一些实施例所示的电容式麦克风的结构示意图。如图1所示，电容式麦克风100可以包括壳体110、振膜120和背板130。其中，壳体110内部具有容置腔，振膜120和背板130设置于容置腔内。振膜120和背板130在容置腔内相对间隔设置，振膜120背离背板130的一侧形成第一腔体111，背板130背离振膜120的一侧形成第二腔体112，第一腔体111及第二腔体112位于振膜120及背板130的相反两侧。壳体110上开设有第一导声孔1111和第二导声孔1121，第一导声孔1111与第一腔体111导通，第一腔体111通过第一导声孔1111与电容式麦克风100外部声学导通，第二导声孔1121与第二腔体112导通，第二腔体112通过第二导声孔1121与电容式麦克风100外部声学导通。在一些实施例中，电容式麦克风100外部的声波可以通过第二导声孔1121进入第二腔体112，并通过背板130及振膜120后穿过第一腔体111，经过第一导声孔1111输出，在此过程中，背板130及振膜120相应产生电信号。在一些实施例中，电容式麦克风100外部的声波可以通过第一导声孔1111进入第一腔体111，再经过第二导声孔1121输出。
壳体110为具有容置腔(即中空部分)的立体结构。在一些实施例中，壳体110可以为长方体、球体、多边体、棱台等规则形状或任意不规则形状的结构体。在一些实施例中，壳体110可以采用金属(例如，不锈钢、铜等)、塑料(例如，聚乙烯(PE)、聚丙烯(PP)、聚氯乙烯(PVC)、聚苯乙烯(PS)及丙烯腈-丁二烯-苯乙烯共聚合物(ABS)等)、复合材料(例如金属基复合材料或非金属基复合材料)、环氧树脂、酚醛、陶瓷、聚酰亚胺、玻璃纤维(例如，FR4-玻璃纤维)等或其任意组合。
振膜120为响应声音信号产生振动的器件。在一些实施例中，振膜120上设置允许气流通过的第一孔阵121，第一孔阵121包括阵列分布的多个微孔，由于空气分子的流动能够产生粘滞力，振膜120会在空气分子粘滞力的带动下上下振动。振膜120上设置的第一孔阵121能够减小声波通过振膜120时的阻力，以使声波损失较少地通过振膜120，这时的空气粘滞力对振膜120有较大影响，能够带动振膜120作振幅较大的振动。
在一些实施例中，为使声波能够损失较少地通过振膜120(即每个孔径中空气分子的振动速度与外界的振动速度相差不多，此时空气分子的粘滞力影响最大)，同时使得声波与振膜120上的微孔有足够大的接触面积，振膜120上的微孔的孔径可以在5μm-50μm范围内。例如，振膜120上的微孔的孔径在10μm-40μm范围内。再例如，振膜120上的微孔的孔径在15μm-30μm范围内。再例如，振膜120上的微孔的孔径在20μm-25μm范围内。
在一些实施例中，为增大空气分子对振膜120的粘滞力，以使振膜120相应产生的振动振幅较大，可以在振膜120上设置数量足够多的微孔。为了达到这个目的，可以将振膜120上的相邻微孔之间的孔间距的最大值设置在50μm以内。这里的孔间距是指微孔边沿与相邻微孔边沿的最小距离。在一些实施例中，相邻微孔之间的孔间距过小，会导致振膜120形成的电极的面积会过少，产生的电信号质量不佳，故可以设置振膜120上的相邻微孔之间的孔间距的最小值在0.1μm以上。在一些实施例中，振膜120上的相邻微孔之间的孔间距可以在0.1μm-50μm范围内。例如，孔间距可以在1μm-30μm范围内。再例如，孔间距可以在1μm-20μm范围内。再例如，孔间距可以在1μm-10μm范围内。
在一些实施例中，微孔形状可以是圆形，也可以是四边形、六边形、八边形等规则或不规则形状。在一些实施例中，为了便于振膜120上第一孔阵121的制作，第一孔阵121的微孔可以是在振膜120上均匀分布的。在一些实施例中，为了使整个振膜120的不同部位能够具有一致的振动位移，可以将第一孔阵121设置为在振膜120上不均匀分布，例如，当振膜120的周侧与壳体110的固定位置相对固定时，为了使整个振膜120能够具有一致的振动位移，第一孔阵121的部分微孔以较大的孔间距分布于振膜120中部，第一孔阵121的部分微孔以较小的孔间距分布于振膜120周边。在一些实施例中，为了便于振膜120上第一孔阵121的制作，第一孔阵121的微孔的孔径可以是一致的。在一些实施例中，为了使整个振膜120的不同部位能够具有一致的振动位移，第一孔阵121也可以是由不同孔径的微孔组合分布的。例如，当振膜120的周侧与壳体110的固定位置相对 固定时，为了使整个振膜120能够具有一致的振动位移，位于振膜120中部的第一孔阵121的部分微孔的孔径较小，位于振膜120周边的第一孔阵121的部分微孔的孔径较大。
在一些实施例中，为使振膜120能够在声波作用下上下振动，振膜120的厚度可以在0.1μm-10μm范围内。例如，振膜120的厚度可以在0.1μm-8μm范围内。再例如，振膜120的厚度可以在0.1μm-5μm范围内。在一些实施例中，可以通过调节振膜120的厚度来调节振膜120的刚性，从而调整电容式麦克风100的灵敏度。在一些实施例中，振膜120可以是具有弹性的薄膜结构。在一些实施例中，为使振膜120具有较好的弹性，从而在声波作用下具有较大的振动幅度，振膜120可以为由丝状结构密集分布形成的网状结构，这里振膜120上的微孔可以为网状结构上的微小网孔。
在一些实施例中，振膜120可以由导电材料(例如，铜、铝、石墨、溅射的金、铂、铝等金属等)形成。在一些实施例中，振膜120可以为不导电的高分子弹性膜，在高分子弹性膜的至少一侧镀有导电层(例如，铝膜层)。示例性的，高分子弹性膜的材料可以包括但不限于聚对苯二甲酸乙二醇酯(PET)、聚碳酸酯(PC)、乙烯基聚合物(PVC)、丙烯腈-丁二烯-苯乙烯共聚物(ABS)、聚乙烯(PE)、聚对二甲苯(Parylene)、聚酰亚胺(PI)中的一种或多种。在一些实施例中，振膜120可以是由导电层和不导电的高分子结构层构成的复合薄膜结构。导电层可以包括溅射的金属(例如，金、铂、铝等)，不导电的高分子结构层可以由聚对二甲苯(Parylene)、聚酰亚胺(PI)等高分子材料制成。在一些实施例中，振膜120的材料可以为硅、氧化硅、氮化硅、碳化硅、塑料材料、树脂材料等或其任意组合。在一些实施例中，振膜120可以完全由导电的多晶硅制成。
背板130可以设置于壳体110内，振膜120相对于背板130的振动可以导致振膜120与背板130之间的电容的变化，以及所生成的电信号的对应变化。可选地，背板130可以基本固定不动地设置于壳体110内，也就是说，在气流通过时，背板130的形状以及相对于壳体110的位置基本保持不变。此时，振膜120和背板130之间的电容变化主要来源于振膜120在气流影响下产生的形变或振动。进一步可选地，背板130可以在气流通过时相对于壳体110产生振动。例如，背板130和振膜120可以具有不同的刚度，在气流通过时形成不同步的形变和振动。此时，振膜120和背板130之间的电容变化主要来源于两者振动的差异。背板130和振膜120在刚度上的差异可以由分别采用不同的材料或者不同的结构实现。在一些实施方式中，可以在背板130中开设一个或更多个孔，使得声波能够通过背板130上的孔穿过背板130。在一些实施方式中，背板130上设置允许气流通过的第二孔阵131，第二孔阵131包括阵列分布的多个微孔。第二孔阵131上的微孔与第一孔阵121上的微孔类似，在此不再赘述。在一些实施例中，背板130上的微孔与振膜120上的微孔位置一一对应，有利于声波直接通过背板130和振膜120，最小化声波的损失。应当理解的是，“一一对应”指振膜120上的每个微孔在背板130上都有与之对应的微孔，且相互对应的两个微孔沿振膜120的振动方向上的投影至少部分重叠，声波可以通过重叠部分对应的微孔。在一些实施例中，为了减少声波通过背板130和振膜120的损失，同时也能保证背板130与振膜120之间具有足够的正对面积，背板130上的微孔与振膜120上的微孔位置一一对应。例如，背板130上的微孔与振膜120上的微孔位置一一对应，且相互对应的两个微孔的面积一致时，声波通过背板130和振膜120的损失较小(可以忽略不计)，振膜120振动的位移最大，同时也能保证背板130与振膜120之间具有足够的正对面积。
在一些实施例中，背板130可以与振膜120近似平行设置。在一些实施例中，背板130与振膜120间隔开设置，两者之间存在空气域。在一些实施例中，声波通过背板130或振膜120进入空气域后，狭小的空气域有利于产生较大的空气粘滞力，带动振膜120振动，同时为避免振膜120振动过程中与背板130发生接触，故背板130与振膜120之间的距离可以在0.5μm-20μm范围内。例如，背板130与振膜120之间的距离可以在1μm-15μm范围内。再例如，背板130与振膜120之间的距离可以在2μm-10μm范围内。
在一些实施例中，背板130与振膜120之间可以设置垫圈，以将二者间隔开设置。在一些实施例中，为了防止振动过程中振膜120与背板130发生接触，可以在振膜120靠近背板130的一侧上设置凸起结构，或者，可以在背板130靠近振膜120的一侧上设置凸起结构，凸起结构作为阻止点，能够有效防止振膜120与背板130发生接触或粘连。
在一些实施例中，背板130材料可以为导电材料。在一些实施例中，背板130可以由多晶硅和氮化硅或者任何其它合适材料(例如，氧化硅、硅、陶瓷等)形成。
背板130与振膜120构成一个平行板电容，声波经空气传播通过背板130或振膜120，由不同方向入射的声波导致的空气分子流动的方向不同，不同流动方向的空气分子产生的粘滞力方向 不同，振膜120在不同方向的粘滞力带动下产生的振幅(即位移)不同，相应地，振膜120与背板130之间的电容变化不同，导致产生的电信号有强弱之分，由此可以实现电容式麦克风100的方向识别。当声波从振膜120的垂直方向入射的时候，因为声波是一个纵波，空气分子的振动方向和声波的传播方向是一致的，那么在垂直入射时，空气的振动方向垂直于振膜120，能够和振膜120之间产生较大的速度差，速度差可以转化成粘滞力，带动振膜120产生较大的振动。当声波的入射方向与振膜120平行时，在振膜120的垂直方向上空气分子的振动较小，那么振膜120的振动较小。所以电容式麦克风100会表现出非常优越的方向性。
图2A和图2B是根据本说明书一些实施例所示的电容式麦克风100在声波方向与振膜120振动方向不同的夹角作用下的响应示图。如图2A和图2B所示，电容式麦克风100在与振膜120的振动方向的夹角呈90°及270°方向上的声波(即声波的入射方向与振膜120平行)作用下，电信号最弱，即声学响应最差；在与振膜120的振动方向的夹角呈0°及180°方向上的声波(即声波的入射方向与振膜120垂直)作用下，电信号最强，即声学响应最好。
仅作为示例，电容式麦克风100可以在0°和180°两个方向上具有均匀的方向性。结合图1和图2A所示，通过对电容式麦克风100的结构设计，可以使得振膜120对来源于第二导声孔1121所在方向(0°)的声波的敏感度最大，且基本等同于对来源于第一导声孔1111所在方向(180°)的声波的敏感度。振膜120对来源于与振动方向垂直的方向(90°或270°)的声波的敏感度最小，此时，振膜120对不同方向的声波的敏感度呈“8”字形状。换句话说，振膜120的振动主要由0°(或180°)及其附近方向的声源产生，振膜120主要采集来源于这些方向的声音，从而使得电容式麦克风100呈现指向性。
作为又一示例，电容式麦克风100可以在0°和180°其中一个方向上具有更强的指向性。结合图1和图2B所示，通过对电容式麦克风100的结构设计，可以使得振膜120对来源于第二导声孔1121所在方向(0°)的声波的敏感度大于来源于第一导声孔1111所在方向(180°)的声波的敏感度。此时，电容式麦克风100能够更好地识别0°及其附近方向的声音。
在一些实施例中，从导声孔进入的空气分子对振膜120的粘滞力大小可以与对应的空气分子流通量和/或空气分子的流动路径(例如，声学路径和物理路径)相关。例如，导声孔对应的空气分子流通量越大，空气分子对振膜120的粘滞力越大，则振膜120对该导声孔对应方向上的声音越敏感。又例如，空气分子从导声孔到振膜120的流动路径的路径长度越长，声波的声压衰减越大，空气分子对振膜120的粘滞力越小，则振膜120对该导声孔对应方向上的声音越不敏感。
因此，可以通过控制导声孔对应的空气分子流通量和/或空气分子的流动路径，来控制电容式麦克风100的方向性。例如，控制第一导声孔1111和第二导声孔1121具有相等的面积，同时对应的空气分子的流动路径具有相等的路径长度，从而使得电容式麦克风100实现如图2A所示的方向性。关于第一导声孔1111和第二导声孔1121具有相等的面积，以及对应的空气分子的流动路径具有相等的路径长度的详细描述可以参见图15及其相关描述，在此不再赘述。又例如，控制第一导声孔1111和第二导声孔1121具有不相等的面积，或者对应的空气分子的流动路径具有不相等的路径长度，从而使得电容式麦克风100实现如图2B所示的方向性。关于第一导声孔1111和第二导声孔1121具有不相等的面积，以及对应的空气分子的流动路径具有不相等的路径长度的详细描述可以参见图16及其相关描述，在此不再赘述。
如图1所示，在一些实施例中，电容式麦克风100还可以包括基底140。在一些实施例中，基底140可以为具有开放式敞口的结构体，振膜120和背板130位于基底140的开放式敞口处并覆盖敞口，基底140中背离振膜120和背板130的一端与壳体110连接，以将容置腔分隔为位于振膜120及背板130相反两侧的第一腔体111及第二腔体112。在一些实施例中，基底140可以为两端贯通的筒状结构，筒状结构的一端与壳体110连接，另一端与振膜120及背板130连接。在一些实施例中，基底140可以采用半导体材料制成。半导体材料可以包括但不限于二氧化硅、氮化硅、氮化镓、氧化锌、碳化硅等。
在一些实施例中，背板130及振膜120可以与基底140通过物理方式进行连接。本说明书中所述的“连接”可以理解为同一结构上不同部位之间的连接，或者在分别制备不同部件或结构后，将各独立部件或结构通过焊接、铆接、卡接、螺栓连接、胶黏剂粘合等方式固定连接，或者在制备过程中，通过物理沉积(例如，物理气相沉积)或者化学沉积(例如，化学气相沉积)的方式将第一部件或结构沉积在第二部件或结构上。
在一些实施例中，为避免基底140与振膜120的连接影响振膜120的振动，振膜120可以与基底140通过刚性或弹性的方式连接。例如，振膜120的周侧可以与基底140敞口内壁弹性连接。 再例如，振膜120的周侧可以与基底140敞口内壁刚性连接。在一些实施例中，背板130的周侧可以与基底140敞口内壁刚性或弹性连接。例如，背板130靠近基底140的侧面可以与基底140远离壳体110的一端刚性连接。再例如，背板130靠近基底140的侧面可以与基底140远离壳体110的一端弹性连接。在一些实施例中，振膜120靠近基底140的侧面可以与基底140远离壳体110的一端弹性连接，背板130的周侧与基底140敞口内壁刚性连接。
如图1所示，在一些实施例中，电容式麦克风100还可以包括处理器150。处理器150可以被配置处理数据和/或信号。在一些实施例中，处理器150可以包括双极型集成电路(如，逻辑门电路、发射极耦合逻辑电路等)、单极型集成电路(如场效应管型集成电路、n沟道场效应管集成电路等)等中的一种或多种。
在一些实施例中，处理器150可以位于壳体110的容置腔或者至少部分悬空设置于壳体110的容置腔。在一些实施例中，处理器150还可以位于壳体110的容置腔之外。例如，处理器150可以设置在壳体110外表面，其可以通过引线160与振膜120及背板130进行信号连接。在一些实施例中，处理器150可以处理目标信号，处理器150可以从振膜120及背板130获取电信号并进行信号处理。
在一些实施例中，电容式麦克风100还可以包括引线160。引线160可以用于将振膜120及背板130和处理器150信号连接。例如，引线160可以传输目标信号或其他信号(如配置指令、采集指令等)。在一些实施例中，引线160可以不是必须的，其功能可以通过其他连接方式实现。
在一些实施例中，振膜120与基底140弹性连接的方式可以如图3所示。图3是根据本说明书一些实施例所示的振膜120与基底140弹性连接的结构示意图。如图3所示，振膜120通过多个弹性结构122与基底140弹性连接。在一些实施例中，多个弹性结构122沿着振膜120周侧对称分布，使得振膜120的受力分布均匀，从而使得振膜120在振动过程中的振动一致性更佳。
在一些实施例中，弹性结构122可以为折叠梁结构。在一些实施例中，折叠梁结构的两端中的一端与基底140连接，另一端与振膜120固定连接。在其他实施例中，弹性结构122可以采用悬臂梁、U形梁等其他具有弹性的梁结构。在一些实施例中，弹性结构122也可以为折环、弹簧、海绵垫、硅胶层等具有弹性的结构。
需要注意的是，以上对于电容式麦克风100的描述，仅为示例性描述，并不能把本说明书限制在所举实施例范围之内。在一些实施例中，基底140可以是不限于相对壳体110独立的结构。在一些实施例中，基底140还可以为壳体110的一部分。在又一些实施例中，振膜120和背板130的位置可以相互交换，背板130背离振膜120的一侧形成第一腔体111，振膜120背离背板130的一侧形成第二腔体112。
电容式麦克风100包括的基底140、背板130及振膜120还有多种设置方式。以下结合图4-图7对基底140、背板130及振膜120的设置方式进行示例性说明。
图4是根据本说明书一些实施例所示的电容式麦克风100的基底140、背板130及振膜120的结构示意图。如图4所示，在一些实施例中，背板130可以包括绝缘层132和导体层133，绝缘层132靠近基底140的一侧与导体层133远离基底140的一侧连接。贯穿绝缘层132和导体层133设置第二孔阵131，导体层133在绝缘层132和振膜120之间，振膜120设置第一孔阵121，第一孔阵121与第二孔阵131对应设置。在一些实施例中，振膜120通过绝缘层141与导体层间隔开设置，绝缘层141形成环状结构，不影响声波通过背板130和振膜120。在一些实施例中，导体层133靠近基底140的一侧与绝缘层141远离基底140的一侧连接，绝缘层141靠近基底140的一侧与振膜120远离基底140的一侧连接。在一些实施例中，振膜120通过绝缘层142与基底140连接，绝缘层142与绝缘层141类似。在一些实施例中，振膜120的靠近基底140的一侧与绝缘层142远离基底140的一侧连接，绝缘层142靠近基底140的一侧与基底140连接。
图5是根据本说明书一些实施例所示的电容式麦克风100的基底140、背板130及振膜120的结构示意图。在一些实施例中，图4中所示的背板130包括的绝缘层132和导体层133可以交换位置。例如，如图5所示，导体层133靠近基底140的一侧与绝缘层132远离基底140的一侧连接，绝缘层132的靠近基底140的一侧与绝缘层141远离基底140的一侧连接。
图6是根据本说明书一些实施例所示的电容式麦克风100的基底140、背板130及振膜120的结构示意图。在一些实施例中，背板130可以包括绝缘层132和导体层133，背板130可以与振膜120交换位置。例如，如图6所示，振膜120靠近基底140的一侧与绝缘层141远离基底140的一侧连接，绝缘层141靠近基底140的一侧与绝缘层132远离基底140的一侧连接，绝缘层132靠近基底140的一侧与导体层133远离基底140的一侧连接，导体层133的靠近基底140的一侧与绝 缘层142远离基底140的一侧连接，绝缘层142靠近基底140的一侧与基底140连接。
在一些实施例中，绝缘层132、绝缘层141及绝缘层142由相同绝缘材料(例如氧化硅或氮化硅)制成。例如，绝缘层132由氮化硅材质制成，氮化硅具有较高的硬度和强度，使得背板130作为固定电极，不易发生变形，从而提高结构的可靠性。在一些实施例中，导电层133可以由多晶硅或金属(例如，铜、铝等)等导电材料制成。
在一些实施例中，第一导声孔和第二导声孔的数量可以是一个或多个。在一些实施例中，第一导声孔的数量和第二导声孔的数量可以相等或者不等。例如，如图1所示，壳体110上可以有1个第一导声孔1111和1个第二导声孔1121。又例如，壳体110上可以有3个第一导声孔1111和3个第二导声孔1121。再例如，壳体110上可以有1个第一导声孔1111和2个第二导声孔1121。
在一些实施例中，一个或多个第一导声孔1111和一个或多个第二导声孔1121的形状可以相同或者不相同。例如，可以是圆形、矩形、多边形、椭圆形、不规则形状等。
在一些实施例中，第一导声孔和第二导声孔可以分别设置在壳体的对侧。如图1所示，壳体110的下侧和上侧上分别开设有第一导声孔1111和第二导声孔1121，第一导声孔1111与第一腔体111导通，第一腔体111通过第一导声孔1111与电容式麦克风100外部声学导通，第二导声孔1121与第二腔体112导通，第二腔体112通过第二导声孔1121与电容式麦克风100外部声学导通。在一些实施例中，由于电容式麦克风100对声波射入的方向是很敏感的，为了避免第一导声孔1111及第二导声孔1121的位置影响声波射入的方向，第一导声孔1111及第二导声孔1121可以正对振膜120设置。其中，正对振膜120设置可以是指在背板130的平面上，振膜120的正投影、第一导声孔1111的正投影和第二导声孔1121的正投影至少部分重合。可以理解，第一导声孔1111及第二导声孔1121可以正对振膜120设置，可以使得空气分子从导声孔流动到振膜120的路径更短，从而使得声波的声压衰减更少。
在一些实施例中，第一导声孔和第二导声孔可以设置在壳体的同侧，如壳体的同一侧面。图14是根据本说明书一些实施例所示的示例性的电容式麦克风的结构示意图。如图14所示，壳体110的下侧同时开设有第一导声孔1111a和第二导声孔1121a，第一导声孔1111a与第一腔体111导通，第一腔体111通过第一导声孔1111a与电容式麦克风100外部声学导通，第二导声孔1121a与第二腔体112导通，第二腔体112通过第二导声孔1121a与电容式麦克风100外部声学导通。此时，第一导声孔1111a和第二导声孔1121a处声压的幅值和/或相位的差异仍然会导致气流在壳体110内的流通。相比于垂直于壳体110下侧入射的声波，电容式麦克风100对来源于两个导声孔连线所在方向的声音更为敏感。
在一些实施例中，第一导声孔和第二导声孔可以分别设置在壳体的任意两侧。例如，相邻侧。图19B是根据本说明书一些实施例所示的示例性的电容式麦克风的结构及其声学路径的示意图。如图19B所示，壳体110的下侧和左侧分别开设有第一导声孔1111d和第二导声孔1121d，第一导声孔1111d与第一腔体111导通，第一腔体111通过第一导声孔1111d与电容式麦克风100外部声学导通，第二导声孔1121d与第二腔体112导通，第二腔体112通过第二导声孔1121d与电容式麦克风100外部声学导通。此时，第一导声孔1111d和第二导声孔1121d处声压的幅值和/或相位的差异仍然会导致气流在壳体110内的流通。
在一些实施例中，空气分子从不同导声孔到振膜的流动路径(例如，声学路径和物理路径)不同，空气分子在壳体110中的流动方向不同。
仅作为示例，电容式麦克风100外部的声波可以通过第二导声孔1121进入第二腔体112，并通过背板130及振膜120后穿过第一腔体111，经过第一导声孔1111输出，在此过程中，背板130及振膜120相应产生电信号。作为又一示例，电容式麦克风100外部的声波可以通过第一导声孔1111进入第一腔体111，再经过第二导声孔1121输出。
在一些实施例中，第一导声孔1111和第二导声孔1121可以具有相等的面积。当存在多个第一导声孔1111和多个第二导声孔1121，第一导声孔1111和第二导声孔1121可以具有相等的面积可以是每个第一导声孔1111和每个第二导声孔1121的面积均相等，也可以是多个第一导声孔1111的面积之和与多个第二导声孔1121的面积之和相等。其中，第一导声孔和/或第二导声孔的面积是指第一导声孔和/或第二导声孔与轴向垂直的截面的最小面积。图15是根据本说明书一些实施例所示的示例性的电容式麦克风的结构示意图。结合图15和图2A所示，当需要振膜120对振膜两侧的空气分子流动的敏感度相同，即声波信号呈“8”字形状时，可以使得第一导声孔1111b和第二导声孔1121b具有相等的面积，避免由于二者面积不同导致第一导声孔1111b和第二导声孔1121b的空气分子的流通量不同，进一步导致振膜120对两侧的空气分子流动的敏感度不同。
在一些实施例中，第一导声孔1111的面积和第二导声孔1121的面积可以不同。当存在多个第一导声孔1111和多个第二导声孔1121，第一导声孔1111和第二导声孔1121的面积不同，可以是指多个第一导声孔1111的面积之和与多个第二导声孔1121的面积之和不相等。图16是根据本说明书一些实施例所示的示例性的电容式麦克风的结构的示意图。如图16所示，第一导声孔1111c的面积S1可以小于第二导声孔1121c的面积S2。在本说明书的一些实施例中，第一导声孔1111和第二导声孔1121的面积不同，可以使得第一导声孔1111和第二导声孔1121的空气分子的流通量不相同，从而使得振膜120对图2A和图2B中0°和180°两个方向上的空气分子流动的敏感度不相同。例如，如图16所示，当振膜120两侧其他影响振膜120振动的变量相同时，第一导声孔1111c的面积S1小于第二导声孔1121c的面积S2，使得第一导声孔1111c的空气分子流通量小于第二导声孔1121c的空气分子流通量，此时第二导声孔1121c一侧的空气分子对振膜120的粘滞力F2大于第一导声孔1111c一侧空气分子对振膜120的粘滞力F1，即振膜120对指向第二导声孔1121c一侧的空气分子流动的敏感度更大，电容式麦克风100可以呈现如图2B所示的指向性。
在一些实施例中，可以通过设置第一导声孔和第二导声孔之间的面积差值，控制声波信号的指向性。例如，第二导声孔的面积与第一导声孔的面积差值越大，则声波信号指向第二导声孔方向(0°)的强度越大。又例如，让第二导声孔的面积小于第一导声孔的面积，使得声波信号的指向第一导声孔方向(180°)。
为了体现出振膜120对图2A和图2B中0°和180°两个方向上的空气分子流动的敏感度的差异，第一导声孔和第二导声孔之间的面积差值需要达到一定阈值。在一些实施例中，第一导声孔1111与第二导声孔1121的面积之差的绝对值与第一导声孔1111的面积之比不小于10％。例如，|S2-S1|/S1可以在10％～30％之间，如10％，20％。又例如，|S2-S1|/S1可以在20％～50％之间，如25％，30％，40％等。在一些实施例中，第一导声孔1111与第二导声孔1121的面积之差的绝对值与第二导声孔1121的面积之比不小于10％。例如，|S2-S1|/S2可以在10％～30％之间，如10％，20％。又例如，|S2-S1|/S2可以在20％～50％之间，如25％，30％，40％等。
在一些实施例中，当需要麦克风在0°和180°两个方向上具有如图2A所示的均匀的方向性时，通过设置第一导声孔的面积与第二导声孔的面积不同，可以调整由于其他因素导致的声波信号在振膜两侧方向上的强度差异。在另一个实施例中，当需要麦克风在0°和180°其中一个方向上具有如图2B所示的指向性时，也可以基于不同面积的导声孔使得空气分子的流通量不相同，从而使得振膜120两侧的空气分子对振膜120的粘滞力不相等，从而调整声波信号的指向性。
在一些实施例中，第一导声孔处和第二导声孔处可以分别布置有对应于不同声阻大小的声阻件。声阻件可以是阻碍空气通过导声孔的元件。在一些实施例中，声组件可以包括但不限于声阻网、防水件等。声阻件的声阻越大，通过的空气分子越少，声波的幅值越小。在一些实施例中，声组件的声阻可以与声阻件的结构、材料相关。例如，声阻网的孔隙率越小，通过的空气分子越少，则对应的声阻越大。又例如，防水件的材料密度越大和/或厚度越大，通过的空气分子越少，则对应的声阻越大。
图17是根据本说明书一些实施例所示的示例性的电容式麦克风结构的示意图。结合图17和图2B所示，仅作为示例，可以分别在第一导声孔1111和第二导声孔1121处设置声阻为R1的声阻网1112和声阻为R2的声阻网1122，其中，声阻网1112的孔隙率大于声阻网1122的孔隙率，声阻R1小于声阻R2，因此声阻网1112可以让更多的空气从第一导声孔1111通过，电容式麦克风100可以呈现如图2B所示的指向性。
在本说明书的一些实施例中，第一导声孔1111和第二导声孔1121处的声阻件的声阻大小不同，可以使得第一导声孔1111和第二导声孔1121的空气分子的流通量不相同，从而使得振膜120两侧的空气分子对振膜120的粘滞力不相等，振膜120对图2A和图2B中0°和180°两个方向上的空气分子流动的敏感度不相同。
在一些实施例中，可以通过设置第一导声孔处和第二导声孔处声阻件的差值，控制声波信号的指向性大小和方向。例如，声阻件的声阻差值越大，则声波信号的指向性越明显，例如，如图2B所示，来源于0°方向的声波信号强度越大。
声学路径可以是空气从导声孔流动到振膜的路径。在一些实施例中，声学路径可以与导声孔与振膜的相对位置、壳体的形状、壳体中部件的相对结构和位置等相关。
在一些实施例中，第一导声孔可以建立让空气流动到振膜背离背板的表面的第一声学路径，第二导声孔可以建立让空气流动到振膜朝向背板的表面的第二声学路径。
声学路径的路径长度可以是空气流动的实际路径的长度。在一些实施例中，当第一导声孔 (或第二导声孔)到振膜存在多条声学路径时，可以将空气从第一导声孔(或第二导声孔)流动到振膜的最短路径作为对应的第一声学路径(或第二声学路径)的路径长度。
在一些实施例中，第一声学路径和第二声学路径可以具有相等的路径长度。在一些实施例中，当存在多个第一导声孔1111和多个第二导声孔1121，第一声学路径的路径长度可以是多个第一导声孔1111对应的多条第一声学路径的路径长度之和，第二声学路径的路径长度可以是多个第二导声孔1121对应的多条第二声学路径的路径长度之和。其中，声学路径的路径长度越长，外部的声波从对应的导声孔到振膜120的声压衰减越大。例如，如图15所示，第一导声孔1111b建立的第一声学路径(图中用向上箭头表示)和第二导声孔1121b建立的第二声学路径(图中用向下箭头表示)的路径长度相同，使得外部的声波从第一导声孔1111b到振膜120的声压衰减等于外部声波从第二导声孔1121b到振膜120的声压衰减，同时使得经过第一声学路径的声波相位变化等于经过第二声学路径的声波相位变化。其中，声波从导声孔到振膜的声压衰减可以视为空气从导声孔流动到振膜的能量衰减。
结合图15和图2A所示，当需要振膜120对两侧的空气分子流动的敏感度相同，声波信号呈“8”字形状时，可以使得第一声学路径和第二声学路径具有相等的路径长度，避免由于二者不同导致空气分子从第一导声孔1111b到振膜120的能量衰减和从第二导声孔1121b到振膜120的能量衰减不同，进一步导致振膜120对两侧的空气分子流动的敏感度不同。
在一些实施例中，第一声学路径和第二声学路径可以具有不相等的路径长度。例如，如图16所示，当振膜120两侧其他影响振膜120振动的变量相同时，第一导声孔1111c建立的第一声学路径的路径长度L1可以小于第二导声孔1121c建立的第二声学路径的路径长度L2，使得外部的声波从第一导声孔1111c到振膜120的声压衰减小于外部声波从第二导声孔1121c到振膜120的声压衰减，同时使得经过第一声学路径的声波相位变化和经过第二声学路径的声波相位变化不同，从而使得第一导声孔1111c一侧空气分子对振膜120的粘滞力F1大于第二导声孔1121c一侧的空气分子对振膜120的粘滞力F2，即振膜120对来源于第一导声孔1111c一侧的空气分子流动的敏感度更大。
为了体现出振膜120对图2A和图2B中0°和180°两个方向上的空气分子流动的敏感度的差异，第一声学路径和所述第二声学路径的路径长度之差需要达到一定阈值。在一些实施例中，第一声学路径和第二声学路径的路径长度之差的绝对值与第一声学路径的路径长度之比不小于10％。例如，|L2-L1|/L1可以在10％～30％之间，如10％，20％。又例如，|L2-L1|/L1可以在20％～50％之间，如25％，30％，40％等。在一些实施例中，第一声学路径和第二声学路径的路径长度之差的绝对值与第二声学路径的路径长度之比不小于10％。例如，|L2-L1|/L2可以在10％～30％之间，如10％，20％。又例如，|L2-L1|/L2可以在20％～50％之间，如25％，30％，40％等。
在一些实施例中，可以通过调整第一声学路径和第二声学路径的路径长度的差值，控制声波信号的指向性大小和方向。例如，第一声学路径和第二声学路径的路径长度的差值越大，则麦克风采集声音的指向性越明显，例如，如图2B所示，麦克风可以更多地采集来源于0°方向的声音。又例如，让第二声学路径的路径长度小于第一声学路径的路径长度，使得麦克风可以更多采集第二导声孔所在方向的声音。
在一些实施例中，可以通过设置振膜120以及背板130在壳体110中的位置，调整第一声学路径和第二声学路径的路径长度。结合图15和图16所示，将振膜120以及背板130在壳体110中的位置设置为更靠近第一导声孔，可以使得第一声学路径的路径长度大于第二声学路径的路径长度。
在一些实施例中，第一声学路径和/或第二声学路径中可以通过布置声延迟元件，延长对应声学路径的物理长度。声学路径的物理长度可以是空气流动的等效路径的长度。
声延迟元件可以是改变声波相位的元件。具体地，声延迟元件可以使部分声波发生反射或干涉，从而使得部分声波经过反射或干涉后再通过导声孔，从而增加声波从导声孔抵达振膜120的时间，延迟声波的相位，等同于增加了声学路径的物理长度。例如，可以仅在第一声学路径上布置声延迟元件，以增加第一声学路径的物理长度。又例如，可以仅在第二声学路径上布置声延迟元件，以增加第二声学路径的物理长度。再例如，可以分别在第一声学路径和第二声学路径设置不同延迟效果的声延迟元件。
在一些实施例中，声延迟元件可以过滤杂质(例如，水、油、灰尘、其他沉积物等)，避免麦克风受到污染。在一些实施例中，声延迟元件可以减轻风噪、冲击等对麦克风的压力波动。
在一些实施例中，声延迟元件可以为梁结构。在一些实施例中，声延迟元件的两端中的一 端或两端可以与壳体110或者基底140连接。图18A和图18B是根据本说明书一些实施例所示的示例性的电容式麦克风的结构及其声学路径的示意图。如图18A所示，第一声学路径中可以布置声延迟元件1113a，声延迟元件1113a可以是一端与基底140连接的悬臂梁。声波在传播的过程中，可以在悬臂梁上产生反射。如图18B所示，第一声学路径中可以布置声延迟元件1113b，声延迟元件1113b的两端可以分别和壳体110上第一导声孔1111的两侧连接。当声波沿着第一声学路径流动时，声波的相位被声延迟元件1113a(或1113b)延迟，使得第一声学路径的物理长度增加。
在本说明书的一些实施例中，当需要麦克风在0°和180°两个方向上具有如图2A所示的均匀的方向性时，通过在声学路径中布置声延迟元件，可以调整由于其他因素导致的声波信号在振膜两侧方向上的强度差异。在另一些实施例中，当需要麦克风在0°和180°其中一个方向上具有如图2B所示的指向性时，也可以基于声延迟元件不同的延迟效果，调整声波信号的指向性。
在一些实施例中，可以通过调整声延迟元件对相位的延迟效果(例如，选用不同反射系数材质的声延迟元件)，控制声波信号的指向性大小和方向。例如，单独在第一声学路径上布置的声延迟元件的延迟效果越好，则第一声学路径的物理长度越长，麦克风采集声音的指向性越明显，例如，如图2B所示，麦克风可以更多地采集0°方向的声音。又例如，第一声学路径上布置的声延迟元件的延迟效果与第二声学路径上布置的声延迟元件的延迟效果差值越大，则麦克风采集声音的指向性越明显。
在一些实施例中，第一声学路径和/或第二声学路径可以包括至少一个弯折段。弯折段可以是改变声波在声学路径中传播方向(即空气在声学路径中流动方向)的元件。具体地，弯折段通过改变声波在声学路径中传播方向，使得声波必然不能沿着原来最短的声学路径传播，从而增加了声波的声学路径的实际路径长度。图19A和图19B是根据本说明书一些实施例所示的示例性的电容式麦克风的结构及其声学路径的示意图。例如，如图19A所示，可以仅在第一声学路径上布置弯折段，改变声波的传播方向，增加声波实际的第一声学路径的路径长度。又例如，如图19B所示，可以仅在第二声学路径上布置弯折段，改变声波的传播方向，增加声波实际的第二声学路径的路径长度。再例如，可以分别在第一声学路径和第二声学路径设置不同形状、数量和/或位置的弯折段，使得实际的第一声学路径的路径长度和实际的第二声学路径的路径长度分别增加不同的长度。
在一些实施例中，多个弯折段的一端或两端可以分别单独与壳体110或者基底140连接。例如，如图19A所示，弯折段1114a和弯折段1114b可以是其中一端分别单独和不同的基底140连接的挡板。在一些实施例中，多个弯折段的一端或两端可以分别相互连接。例如，如图19B所示，弯折段1124a的一端可以和壳体110连接，弯折段1124a的另一端可以和弯折段1124b的一端连接，弯折段1124b的另一端可以和弯折段1124c的一端连接。
在本说明书的一些实施例中，当需要麦克风在0°和180°两个方向上具有如图2A所示的均匀的方向性时，通过在声学路径中布置弯折端，可以调整由于其他因素导致的声波信号在振膜两侧方向上的强度差异。在一些实施例中，当需要麦克风在0°和180°其中一个方向上具有如图2B所示的指向性时也可以基于弯折段对声学路径的不同延长效果，调整麦克风采集声音的指向性。
在一些实施例中，可以通过调整第一声学路径和第二声学路径的路径长度物理长度的差值，减少由于第一导声孔1111的空气通量和第二导声孔1121的空气通量不同导致的振膜120两侧对空气分子流动的敏感度的差异。例如，当第一导声孔1111的空气分子流通量小于第二导声孔1121的空气分子流通量且第一声学路径和第二声学路径的路径长度/物理长度相等时，振膜120对指向第二导声孔1121一侧的空气分子流动的敏感度更大，麦克风对来源于第二导声孔1121所在方向(0°)的声音更敏感。在一些情况下，为了使得麦克风的指向性呈“8”字形，可以调整第一声学路径的路径长度/物理长度L1小于第二声学路径的路径长度/物理长度L2，让外部的声波从第一导声孔1111到振膜120的声压衰减小于外部声波从第二导声孔1121到振膜120的声压衰减，从而使得振膜120对两侧的空气分子流动的敏感度相同。例如，可以使振膜120到第一导声孔的距离更近。又例如，可以在第二声学路径中布置声延迟元件。再例如，可以在第二声学路径设置至少一个弯折段。
在一些实施例中，可以通过调整第一导声孔1111的空气通量和第二导声孔1121的空气通量的差值，减少由于第一声学路径和第二声学路径的路径长度/物理长度的差值导致的振膜120两侧对空气分子流动的敏感度的差异。例如，当第一声学路径的路径长度/物理长度大于第二声学路径的路径长度/物理长度且第一导声孔1111的空气通量和第二导声孔1121的空气通量相等时，振膜120对来源于第二导声孔1121一侧的空气分子流动的敏感度更大，麦克风会更多采集来源于第二导声孔1121所在方向的声音。在一些情况下，为了使得麦克风的指向性呈“8”字形，可以调整第一导声孔的空气通量大于第二导声孔的空气通量，从而使得振膜120对两侧的空气分子流动的敏感度相 同。例如，可以增加第一导声孔1111的面积或者减少第二导声孔1121的面积。又例如，可以在第一导声孔1111和第二导声孔1121分别布置声组件，使得第一导声孔1111处的声阻件的声阻小于第二导声孔1121处的声阻件的声阻。
在一些实施例中，可以通过调整第一声学路径和第二声学路径的路径长度//物理长度的差值和/或调整第一导声孔1111的空气通量和第二导声孔1121的空气通量的差值，使得声波信号的强度具有指向性。例如，门上监控功能的麦克风需要清楚地接收门外的声音，且尽量避免门内的声音对麦克风的信号干扰，则需要使得麦克风采集声音的指向性指向门外的方向。因此，可以减少门内方向上的第一导声孔的空气通量和/或增加门外方向上的第二导声孔的空气通量，和/或者，增加第一声学路径的长度和/或减少第二声学路径的长度。例如，减少第一导声孔的面积和/或增加第二导声孔的面积。又例如，增加第一导声孔处的声阻件的声阻。再例如，可以在第一声学路径上设置延迟元件、弯折段等。
图7是根据本说明书一些实施例所示的电容式麦克风100的基底140、背板130及振膜120的结构示意图。如图7所示，在一些实施例中，背板130可以包括第一背板134和第二背板135，第一背板134和第二背板135可以与图4-图6所示的背板130类似。第一背板134和第二背板135上均设置第二孔阵131，振膜120上的第一孔阵121与第二孔阵131对应设置。第一背板134和第二背板135与基底140连接，振膜120设置于第一背板134和第二背板135之间，第一背板134与振膜120间隔开设置形成第一电容，第二背板135与振膜120间隔开设置形成第二电容。振膜120在声波作用下振动，从而使得第一电容及第二电容的电容值发生变化。在一些实施例中，第一电容和第二电容构成差分电容，在工作过程中，输出差分信号。在一些实施例中，当振膜120朝向第一背板134振动时，第一背板134与振膜120形成的第一电容的电容值增大，第二背板135与振膜120形成的第二电容的电容值减小；当振膜120朝向第二背板135振动时，第一背板134与振膜120形成的第一电容的电容值减小，第二背板135与振膜120形成的第二电容的电容值增大。第一电容和第二电容的差分信号增大，因此可以提高电容式麦克风100的灵敏度和信噪比。
图8是根据本说明书一些实施例所示的示例性电容式麦克风800的示例性结构示意图。如图8所示，电容式麦克风800可以包括壳体810、固定电极820、可移动电极830和基底840。其中，壳体810内部具有容置腔，固定电极820、可移动电极830和基底840设置于容置腔内。固定电极820和可移动电极830在容置腔内在第一方向上相对间隔设置以形成电容。
在一些实施例中，固定电极820基本不动地固定在所述基底840上，可移动电极830安装在基底840上，可移动电极830上至少一部分被配置为沿第二方向振动。在一些实施例中，第二方向可以垂直于第一方向。在一些实施例中，可移动电极830相对于固定电极820的振动可以改变固定电极820与可移动电极830之间沿第一方向的正对面积，以产生电容的变化。固定电极820与可移动电极830之间的正对面积指固定电极820与可移动电极830的两个相对面沿第一方向上投影的重合面积。在一些实施例中，可移动电极830可以为单端固支或双端固支的梁结构。例如，可移动电极830为单端固支的梁结构时，没有固定的一端悬空设置，可以沿第二方向振动；可移动电极830为双端固支的梁结构时，两个固定端中间的悬空部可以沿第二方向振动。在一些实施例中，固定电极820和/或可移动电极830的材料可以与振膜120的材料类似，在此不做赘述。
在一些实施例中，如图8所示，壳体810上开设有在固定电极820和可移动电极830沿第二方向的两侧分别设置的第三导声孔8111和第四导声孔8121。在一些实施例中，电容式麦克风800外部的声波可以通过第四导声孔8121进入壳体810，并带动可移动电极830沿第二方向振动，经过所述固定电极820和可移动电极830的间隔后，沿第三导声孔8111输出。在此过程中，固定电极820和可移动电极830响应产生电信号。在一些实施例中，电容式麦克风800外部的声波可以通过第三导声孔8111进入壳体810，并带动可移动电极830沿第二方向振动，经过所述固定电极820和可移动电极830的间隔后，沿第四导声孔8121输出。
在一些实施例中，壳体810可以与图1所示的壳体110具有类似的结构材料等，基底840可以与图1所示的基底140具有类似的结构材料等，在此不做赘述。在一些实施例中，电容式麦克风800还可以包括如图1所示的处理器150和/或引线160，在此不做赘述。
在一些实施例中，固定电极820和可移动电极830构成一个平行板电容，声波经空气传播通过导声孔(第三导声孔8111或第四导声孔8121)后，由不同方向入射的声波导致的空气分子流动的方向不同，不同流动方向的空气分子使得可移动电极830沿第二方向振动的振幅(即位移)不同，相应地，使得可移动电极830与固定电极820之间的正对面积不同，进而产生不同的电容，导致产生的电信号有强弱之分，由此可以实现电容式麦克风100的方向识别。当声波从第二方向入射 的时候，空气沿第二方向振动，带动可移动电极830产生沿第二方向较大的振动。当声波从第一方向入射时，在第二方向上空气分子的振动较小，可移动电极830沿第二方向上的振动较小。所以电容式麦克风800会表现出优越的方向性。
在一些实施例中，由于电容式麦克风800对声波射入的方向是很敏感的，为了避免第三导声孔8111及第四导声孔8121的位置影响声波射入的方向，第三导声孔8111及第四导声孔8121可以正对固定电极820和可移动电极830的间隔设置。
在一些实施例中，固定电极820和/或可移动电极830的结构可以具有不同的变化例。例如，固定电极820和/或可移动电极830可以为一个整体电极。再例如，固定电极820和/或可移动电极830可以包括多个子电极。图9是根据本申请一些实施例所示的示例性电容式麦克风800的示例性结构示意图。如图9所示，固定电极820可以包括沿第一方向上间隔排布的多个第一电极821，可移动电极830可以包括沿第一方向上间隔排布的多个第二电极831。在一些实施例中，为使声波能够损失较少地通过固定电极820和可移动电极830，同时使得声波与可移动电极830有足够大的接触面积，固定电极820中任意一个第一电极821和可移动电极830上与该第一电极821相邻的第二电极831之间的空隙沿第一方向的距离可以在5μm-50μm范围内。例如，每个第一电极821和与之相邻的第二电极831之间的空隙沿第一方向的距离可以10μm-40μm范围内。再例如，每个第一电极821和与之相邻的第二电极831之间的空隙沿第一方向的距离可以15μm-30μm范围内。再例如，每个第一电极821和与之相邻的第二电极831之间的空隙沿第一方向的距离可以20μm-25μm范围内。
在一些实施例中，为了便于固定电极820和可移动电极830的制作，每个第一电极821和与之相邻的第二电极831之间的空隙沿第一方向的距离可以相同。在一些实施例中，为了使整个可移动电极830的不同部位能够具有一致的振动位移，第一电极821和与之相邻的第二电极831之间的空隙沿第一方向的距离可以不同。例如，当固定电极820的周侧与壳体810的固定位置相对固定时，为了使整个可移动电极830能够具有一致的振动位移，靠近基底840的周边位置处相邻第一电极821和第二电极831之间的空隙沿第一方向上的距离可以小于远离基底840的中心位置处相邻第一电极821和第二电极831之间的空隙沿第一方向上的距离。
在一些实施例中，多个第一电极821可以分别基本不动地固定在所述基底840上。多个第二电极831可以分别为单端固支或双端固支的梁结构。例如，每个第二电极831的一端或两端可以固定在基底840上，使第二电极831可以沿第二方向振动。
在一些实施例中，固定电极820中的每个第一电极821可以包括沿第二方向上间隔分布的多个子电极层，每两个相邻的子电极层之间通过子绝缘层隔开。如图8所示，固定电极820中的每个第一电极821可以包括沿第二方向上分别分布的第一子电极层8211、第一子绝缘层8212、第二子电极层8213、第二子绝缘层8214和第三子电极层8215。在一些实施例中，当可移动电极830中的任意一个第二电极831沿第二方向移动时，所述第二电极831与第一子电极层8211形成第一子电容，第二电极831与第二子电极层8213形成第二子电容，第二电极831与第三子电极层8215形成第三子电容。第二电极831在声波作用下振动，从而使得第一子电容、第二子电容和第三子电容的电容值发生变化。在一些实施例中，任意两个子电容之间可以构成差分电容。例如，第一子电容和第二子电容构成差分电容，在工作过程中，输出差分信号。在一些实施例中，当第二电极831朝向第一子电极层8211的方向振动时，第二电极831与第一子电极层8211形成的第一子电容的电容值增大，第二电极831与第二子电极层8213形成的第二子电容的电容值减小。第一子电容和第二子电容的差分信号增大，因此可以提高电容式麦克风800的灵敏度和信噪比。
图10是根据本说明书一些实施例所示的示例性麦克风1000的结构示意图。图10所示的麦克风1000可以是本说明书中图8-图9所述的电容式麦克风，也可以是其他类型的麦克风(例如，压电式麦克风、压阻式麦克风等)。如图10所示，麦克风1000可以包括基底1040、固定电极1020和可移动电极1030。在一些实施例中，为了提高可移动电极1030的柔性从而增加可移动电极1030振动的振幅(即沿垂直纸面方向振动的位移)，可移动电极1030的材料可以包括塑料、树脂等较软的材料。在一些实施例中，为了提高可移动电极1030的柔性从而增加可移动电极1030振动的振幅(即垂直纸面方向振动的位移)，可移动电极1030可以是具有弯曲结构的电极。如图10所示，可移动电极1030可以为蛇形结构的电极。应当理解的是，图10所示的蛇形结构的电极仅为示例，可移动电极1030的弯曲结构可以是其它能够增大移动电极1030延伸长度的结构，例如，S形、W型、V型、U型等。在一些实施例中，弯折结构中弯折单元的数量可以在1-10个范围内。这里“弯折单元”指弯折结构中延伸方向不同的相邻部分之间的连接部。
在一些实施例中，可移动电极1030为双端固支的梁结构时，弯曲结构的两个固定端可以分别在基底1040沿第三方向(如图10所示)上的两侧，也可以在基底1040沿第三方向上的同一侧。在一些实施例中，为了提高可移动电极1030的柔性从而增加可移动电极1030振动的振幅，所述弯曲结构的总长度与两个固定端之间沿第三方向上的距离的比值大于1。在一些实施例中，可移动电极1030为单端固支梁结构时，弯曲结构的固定端可以在基底1040沿第三方向上的任意一侧。在一些实施例中，为了提高可移动电极1030的柔性从而增加可移动电极1030振动的振幅，所述弯曲结构的宽度可以在0.1μm-30μm范围内，厚度可以在0.1μm-30μm范围内。在一些实施例中，为了避免弯曲结构形变碰撞固定电极1020，可移动电极1030与固定电极1020之间在第一方向和第三方向定义的平面内的间距可以在5μm-50μm范围内。例如，可移动电极1030与固定电极1020的任意两个相邻部位之间在第一方向和第三方向定义的平面内的间距可以在5μm-50μm范围内。
图11是根据本说明书一些实施例所示的示例性麦克风1000的结构示意图。图11所示的麦克风1000可以是本说明书中图8-图9所述的电容式麦克风，也可以是其他类型的麦克风(例如，压电式麦克风、压阻式麦克风等)。如图11所示，麦克风1000可以包括基底1040、固定电极1020和可移动电极1030。固定电极1020可以包括多个固定悬臂梁1021。在一些实施例中，固定悬臂梁1021可以基本不动地固定在所述基底1040上。可移动电极1030可以包括多个可动悬臂梁1031和连接梁1032。所述多个固定悬臂梁1021与所述多个可动悬臂梁1031在第一方向上相对隔开设置以形成电容。在一些实施例中，所述多个可动悬臂梁1031的一端固定在所述基底1040上，另外一端(自由端，即非固定端)之间通过连接梁1032连接。由于每个可动悬臂梁1031上振幅最大的部位为自由端，因此将多个可动悬臂梁1031的自由端通过连接梁1032连接，连接梁1032处的振幅最大，因此相对于自由端没有连接梁1032的情况，多个可动悬臂梁1031的自由端通过连接梁1032连接增加了连接梁1032与固定电极1020(即多个固定悬臂梁1021)之间形成的电容，提高了麦克风1000的灵敏度。
在一些实施例中，为了增加连接梁1032处的振幅，连接梁1032的材料可以与多个可动悬臂梁1031的材料不同。例如，连接梁1032的材料的弹性模量可以小于多个可动悬臂梁1031的材料的弹性模量，以增加连接梁1032处的振幅，增加连接梁1032与固定电极102之间形成的电容，提高麦克风1000的灵敏度。在一些实施例中，为了方便可移动电极1030的制备，连接梁1032的材料可以与多个可动悬臂梁1031的材料相同。例如，连接梁1032的材料可以与多个可动悬臂梁1031的材料相同，且通过一体成型制成。
在一些实施例中，为了提高可移动电极1030的柔性从而增加可移动电极1030振动的振幅，所述可动悬臂梁1031和/或连接梁1032的宽度可以在0.1μm-30μm范围内，所述可动悬臂梁1031和/或连接梁1032的厚度可以在0.1μm-30μm范围内。在一些实施例中，为了使声音带动空气分子，进一步带动可动悬臂梁1031的振动，同时能够得到较高的灵敏度，可动悬臂梁1031的宽度与连接梁1032的宽度可以相同。在一些实施例中，为了避免弯曲结构形变碰撞固定电极1020，可移动电极1030(例如，可动悬臂梁1031和/或连接梁1032)与固定电极1020之间在纸面平面内的间距可以在5μm-50μm范围内。例如，可移动电极1030(例如，可动悬臂梁1031和/或连接梁1032)与固定电极1020的任意两个相邻部位之间在纸面平面内的间距可以在5μm-50μm范围内。在一些实施例中，为了使声音带动空气分子，进一步带动可动悬臂梁1031的振动，同时能够得到较高的灵敏度，可动悬臂梁1031与固定电极1020之间在纸面平面内的间距与连接梁1032与固定电极1020之间在纸面平面内的间距相同。
在一些实施例中，第一可移动电极1120可以包括多个一端固定的第一可动悬臂梁1121。第二可移动电极1130可以包括多个一端固定的第二可动悬臂梁1131。所述多个第一可动悬臂梁1121与所述多个第二可动悬臂梁1131在第一方向上相对隔开设置以形成电容。图13是根据本说明书一些实施例所示的示例性第一可动悬臂梁1121和第二可动悬臂梁1131的结构示意图。如图12和图13所示，所述多个第一可动悬臂梁1121的固定端11210与所述多个第一可动悬臂梁1121的自由端11211位于所述多个第一可动悬臂梁1121的第三方向上的相对两端。所述多个第二可动悬臂梁1131的自由端11311与所述多个第二可动悬臂梁1131的固定端11310位于所述多个第二可动悬臂梁1131的第三方向上的相对两端。所述多个第一可动悬臂梁1121与所述多个第二可动悬臂梁1131在第一方向上相邻隔开设置。例如，如图12所示，所述多个第一可动悬臂梁1121的固定端11210和所述多个第二可动悬臂梁1131的自由端11311沿第一方向依次相邻设置；所述多个第一可动悬臂梁1121的自由端11211和所述多个第二可动悬臂梁1131的固定端11310沿第一方向依次相邻设置。由于每个第一可动悬臂梁1121和每个第二可动悬臂梁1131的最大位移集中在自由端(即 非固定端)，而固定端的位移很小。因此，所述多个第一可动悬臂梁1121和所述多个第二可动悬臂梁1131之间分别间隔排布，使得每个第一可动悬臂梁1121的自由端11211与相邻的第二可动悬臂梁1131的固定端11310构成第一电容，每个第一可动悬臂梁1121的固定端11210与相邻的第二可动悬臂梁1131的自由端11311构成第二电容。在第一可移动电极1120和第二可移动电极1130振动的过程中，多个第一电容和多个第二电容并联，提高了麦克风1000的灵敏度。
在一些实施例中，为了提高第一可移动电极1120和第二可移动电极1130的柔性从而增加第一可移动电极1120和第二可移动电极1130振动的振幅，所述第一可移动电极1120和第二可移动电极1130的宽度可以在0.1μm-30μm范围内，厚度可以在0.1μm-30μm范围内。
在一些实施例中，当需要振膜120对振膜两侧的空气分子流动的敏感度相同，即声波信号呈“8”字形状时，第三导声孔8111和第四导声孔8121可以具有相等的开口面积，从而避免由于二者面积不同导致第三导声孔8111和第四导声孔8121的空气分子的流通量不同，进一步导致振膜120对两侧的空气分子流动的敏感度不同。
在一些实施例中，当需要振膜120对振膜两侧的空气分子流动的敏感度不相同，即声波信号具有指向性时，第三导声孔的面积与第四导声孔的面积可以不同。在一些实施例中，第三导声孔与第四导声孔的面积之差的绝对值与第三导声孔的面积之比可以不小于10％。在一些实施例中，第三导声孔与第四导声孔的面积之差的绝对值与第四导声孔的面积之比可以不小于10％。
在一些实施例中，第三导声孔8111处和第四导声孔8121处可以分别布置有对应于不同声阻大小的声阻件。
关于第三导声孔8111和第四导声孔8121及其相关元件布置的详细描述可以参见对第一导声孔1111和第二导声孔1121的相关描述。
在一些实施例中，第三导声孔8111可以建立让空气流动到可移动电极背离固定电极的表面的第三声学路径，第四导声孔8121可以建立让空气流动到可移动电极朝向固定电极的表面的第四声学路径。
在一些实施例中，当需要振膜120对振膜两侧的空气分子流动的敏感度相同，即声波信号呈“8”字形状时，第三声学路径和第四声学路径可以具有相等的路径长度，从而避免由于二者不同导致空气分子从第三导声孔8111到振膜120的能量衰减和从第四导声孔8121到振膜120的能量衰减不同，进一步导致振膜120对两侧的空气分子流动的敏感度不同。
在一些实施例中，当需要振膜120对振膜两侧的空气分子流动的敏感度不相同，即声波信号具有指向性时，第三声学路径和第四声学路径可以具有不相等的路径长度。在一些实施例中，第三声学路径和第四声学路径的路径长度之差的绝对值与第三声学路径的路径长度之比可以不小于10％。在一些实施例中，第三声学路径和第四声学路径的路径长度之差的绝对值与第四声学路径的路径长度之比可以不小于10％。
在一些实施例中，第三声学路径和/或第四声学路径中可以布置声延迟元件，声延迟元件被配置为延长对应声学路径的物理长度。在一些实施例中，第三声学路径和/或第四声学路径均可以包括至少一个弯折段。
关于第三声学路径和第四声学路径及其相关元件布置的详细描述可以参见对第一声学路径和第二声学路径的相关描述。
本说明书实施例可能带来的有益效果包括但不限于：(1)通过在背板和振膜上设计微孔结构，使振膜在不同方向的声音信号下产生不同的振动，使电容式麦克风具有方向性；(2)通过设计微孔的孔径、相邻微孔间的孔间距等，可以使声波损失较少地通过振膜，以提高电容式麦克风的灵敏度；(3)通过设计背板与振膜之间的距离或在背板与振膜之间设置凸起结构，避免振膜在振动过程中与背板发生接触；(4)通过设计振膜与基底之间的弹性结构，避免基底与振膜的连接影响振膜的振动；(5)通过设计两个背板与振膜形成两个电容，根据两个电容的差分信号可以提高电容式麦克风的灵敏度和信噪比；(6)通过设计电容式麦克风中的固定电极和/或可移动电极，使可移动电极在不同方向的声音信号下产生不同的振动，使电容式麦克风具有方向性。
需要知道的是，图1-图13仅用于示例性描述，并不对其构成限制。对于本领域的普通技术人员来说，根据本申请的指导可以做出多种变化和修改。不同实施例可能产生的有益效果不同，在不同的实施例里，可能产生的有益效果可以是以上任意一种或几种的组合，也可以是其他任何可能获得的有益效果。
上文已对基本概念做了描述，显然，对于本领域技术人员来说，上述详细披露仅仅作为示例，而并不构成对本申请的限定。虽然此处并没有明确说明，本领域技术人员可能会对本申请进行 各种修改、改进和修正。该类修改、改进和修正在本申请中被建议，所以该类修改、改进、修正仍属于本申请示范实施例的精神和范围。
同时，本申请使用了特定词语来描述本申请的实施例。如“一个实施例”、“一实施例”、和/或“一些实施例”意指与本申请至少一个实施例相关的某一特征、结构或特点。因此，应强调并注意的是，本说明书中在不同位置两次或多次提及的“一实施例”或“一个实施例”或“一个替代性实施例”并不一定是指同一实施例。此外，本申请的一个或多个实施例中的某些特征、结构或特点可以进行适当的组合。
此外，除非权利要求中明确说明，本申请处理元素和序列的顺序、数字字母的使用、或其他名称的使用，并非用于限定本申请流程和方法的顺序。尽管上述披露中通过各种示例讨论了一些目前认为有用的发明实施例，但应当理解的是，该类细节仅起到说明的目的，附加的权利要求并不仅限于披露的实施例，相反，权利要求旨在覆盖所有符合本申请实施例实质和范围的修正和等价组合。例如，虽然以上所描述的系统组件可以通过硬件设备实现，但是也可以只通过软件的解决方案得以实现，如在现有的服务器或移动设备上安装所描述的系统。
同理，应当注意的是，为了简化本申请披露的表述，从而帮助对一个或多个发明实施例的理解，前文对本申请实施例的描述中，有时会将多种特征归并至一个实施例、附图或对其的描述中。但是，这种披露方法并不意味着本申请对象所需要的特征比权利要求中提及的特征多。实际上，实施例的特征要少于上述披露的单个实施例的全部特征。
一些实施例中使用了描述成分、属性数量的数字，应当理解的是，此类用于实施例描述的数字，在一些示例中使用了修饰词“大约”、“近似”或“大体上”来修饰。除非另外说明，“大约”、“近似”或“大体上”表明数字允许有±20％的变化。相应地，在一些实施例中，说明书和权利要求中使用的数值参数均为近似值，该近似值根据个别实施例所需特点可以发生改变。在一些实施例中，数值参数应考虑规定的有效数位并采用一般位数保留的方法。尽管本申请一些实施例中用于确认其范围广度的数值域和参数为近似值，在具体实施例中，此类数值的设定在可行范围内尽可能精确。
针对本申请引用的每个专利、专利申请、专利申请公开物和其他材料，如文章、书籍、说明书、出版物、文档等，特此将其全部内容并入本申请作为参考。与本申请内容不一致或产生冲突的申请历史文件除外，对本申请权利要求最广范围有限制的文件(当前或之后附加于本申请中的)也除外。需要说明的是，如果本申请附属材料中的描述、定义、和/或术语的使用与本申请内容有不一致或冲突的地方，以本申请的描述、定义和/或术语的使用为准。
最后，应当理解的是，本申请中实施例仅用以说明本申请实施例的原则。其他的变形也可能属于本申请的范围。因此，作为示例而非限制，本申请实施例的替代配置可视为与本申请的教导一致。相应地，本申请的实施例不仅限于本申请明确介绍和描述的实施例。

Claims (39)

  1. 一种电容式麦克风，包括：
    振膜，所述振膜上设置允许气流通过的第一孔阵；以及
    背板，所述背板上设置允许气流通过的第二孔阵，所述振膜和所述背板相对隔开设置以形成电容。
  2. 根据权利要求1所述的电容式麦克风，所述振膜上第一孔阵中每个孔的孔径在5μm-50μm范围内；或所述背板上第二孔阵中每个孔的孔径在5μm-50μm范围内。
  3. 根据权利要求1或权利要求2所述的电容式麦克风，所述振膜上第一孔阵中两个相邻孔之间的间距在0.1μm-50μm范围内；或所述背板上第二孔阵中两个相邻孔之间的间距在0.1μm-50μm范围内。
  4. 根据权利要求1-3中任意一项所述的电容式麦克风，所述背板与所述振膜之间的距离在0.5μm-20μm范围内。
  5. 根据权利要求1-4中任意一项所述的电容式麦克风，所述振膜与所述背板上的孔的位置一一对应。
  6. 根据权利要求1-5中任意一项所述的电容式麦克风，还包括基底，所述振膜的周侧与所述基底弹性连接。
  7. 根据权利要求6所述的电容式麦克风，所述振膜的周侧通过多个对称分布的弹性结构与所述基底弹性连接。
  8. 根据权利要求6或权利要求7所述的电容式麦克风，所述背板的周侧与所述基底刚性连接。
  9. 根据权利要求1-8中任意一项所述的电容式麦克风，所述背板朝向所述振膜的表面或所述振膜朝向所述背板的表面上设置有凸起结构。
  10. 根据权利要求1-9中任意一项所述的电容式麦克风，所述背板包括导体层和绝缘层，所述导体层在所述绝缘层和所述振膜之间。
  11. 根据权利要求1-9中任意一项所述的电容式麦克风，所述背板包括导体层和绝缘层，所述绝缘层在所述导体层和所述振膜之间。
  12. 根据权利要求1-11中任意一项所述的电容式麦克风，所述背板包括第一背板和第二背板，所述第一背板与所述第二背板分别设置于所述振膜的两侧，所述振膜和所述第一背板相对隔开设置以形成第一电容，所述振膜与所述第二背板相对隔开设置以形成第二电容。
  13. 根据权利要求1-12中任意一项所述的电容式麦克风，所述振膜的厚度在0.1μm-10μm范围内。
  14. 根据权利要求1-13中任意一项所述的电容式麦克风，所述第一孔阵在所述振膜上不均匀分布。
  15. 根据权利要求1所述的电容式麦克风，还包括容纳所述振膜和背板的壳体，所述壳体上具有第一导声孔和第二导声孔，所述第一导声孔建立让空气流动到所述振膜背离所述背板的表面的第一声学路径，所述第二导声孔建立让空气流动到所述振膜朝向所述背板的表面的第二声学路径。
  16. 根据权利要求15所述的电容式麦克风，所述第一声学路径和所述第二声学路径具有相等的路径长度。
  17. 根据权利要求15所述的电容式麦克风，所述第一导声孔和所述第二导声孔具有相等的开口面积。
  18. 根据权利要求15所述的电容式麦克风，所述第一声学路径和所述第二声学路径具有不相等的路径长度；
    所述第一声学路径和所述第二声学路径的路径长度之差的绝对值与所述第一声学路径的路径长度之比不小于10％；或者，
    所述第一声学路径和所述第二声学路径的路径长度之差的绝对值与所述第二声学路径的路径长度之比不小于10％。
  19. 根据权利要求15所述的电容式麦克风，所述第一导声孔的面积与所述第二导声孔的面积不同；
    所述第一导声孔与所述第二导声孔的面积之差的绝对值与所述第一导声孔的面积之比不小于10％；或者，
    所述第一导声孔与所述第二导声孔的面积之差的绝对值与所述第二导声孔的面积之比不小于10％。
  20. 根据权利要求15所述的电容式麦克风，所述第一导声孔处和所述第二导声孔处分别布置有对应于不同声阻大小的声阻件。
  21. 根据权利要求15所述的电容式麦克风，所述第一声学路径和/或所述第二声学路径中布置声延迟元件，所述声延迟元件被配置为延长对应声学路径的物理长度。
  22. 根据权利要求15所述的电容式麦克风，所述第一声学路径和/或所述第二声学路径均包括至少一个弯折段。
  23. 一种电容式麦克风，包括：
    基底；
    固定电极，所述固定电极固定在所述基底上；以及
    可移动电极，所述可移动电极固定在所述基底上，所述固定电极与所述可移动电极在第一方向上相对隔开设置以形成电容，所述可移动电极被配置为沿着垂直于所述第一方向的第二方向振动，所述振动改变所述固定电极和所述可移动电极沿第一方向的正对面积。
  24. 根据权利要求23所述的电容式麦克风，所述固定电极包括沿所述第一方向上间隔排布的多个第一电极，所述可移动电极包括沿所述第一方向上间隔分布的多个第二电极。
  25. 根据权利要求23或权利要求24所述的电容式麦克风，所述可移动电极的一端固定在所述基底上。
  26. 根据权利要求23或权利要求24所述的电容式麦克风，所述可移动电极的两端固定在所述基底上。
  27. 根据权利要求23-26中任意一项所述的电容式麦克风，所述可移动电极具有弯曲结构。
  28. 根据权利要求27所述的电容式麦克风，所述弯曲结构的宽度在0.1μm-30μm范围内。
  29. 根据权利要求27或权利要求28所述的电容式麦克风，所述弯曲结构的厚度在0.1μm-30μm范围内。
  30. 根据权利要求23-29中任意一项所述的电容式麦克风，所述固定电极包括沿着所述第二方向分布的多个子电极层，每两个相邻的子电极层之间通过子绝缘层隔开。
  31. 根据权利要求23所述的电容式麦克风，所述固定电极包括多个固定悬臂梁；所述可移动电极包括多个可动悬臂梁，多个固定悬臂梁与所述多个可动悬臂梁在第一方向上相对隔开设置，所述多个可动悬臂梁的一端固定在所述基底上，所述多个可动悬臂梁的另外一端通过连接梁连接，所述连接梁与固定电极之间形成的电容。
  32. 根据权利要求23所述的电容式麦克风，还包括壳体，所述壳体容纳所述基底、所述固定电极和所述可移动电极；所述壳体上具有第三导声孔和第四导声孔，所述第三导声孔建立让空气流动到所述可移动电极背离所述固定电极的表面的第三声学路径，所述第四导声孔建立让空气流动到所述可移动 电极朝向所述固定电极的表面的第四声学路径。
  33. 根据权利要求32所述的电容式麦克风，所述第三声学路径和所述第四声学路径具有相等的路径长度。
  34. 根据权利要求32所述的电容式麦克风，所述第三导声孔和所述第四导声孔具有相等的开口面积。
  35. 根据权利要求32所述的电容式麦克风，所述第三声学路径和所述第四声学路径具有不相等的路径长度；
    所述第三声学路径和所述第四声学路径的路径长度之差的绝对值与所述第三声学路径的路径长度之比不小于10％；或者，
    所述第三声学路径和所述第四声学路径的路径长度之差的绝对值与所述第四声学路径的路径长度之比不小于10％。
  36. 根据权利要求32所述的电容式麦克风，所述第三导声孔的面积与第四导声孔的面积不同；
    所述第三导声孔与所述第四导声孔的面积之差的绝对值与所述第三导声孔的面积之比不小于10％；或者，
    所述第三导声孔与所述第四导声孔的面积之差的绝对值与所述第四导声孔的面积之比不小于10％。
  37. 根据权利要求23所述的电容式麦克风，所述第三导声孔处和所述第四导声孔处分别布置有对应于不同声阻大小的声阻件。
  38. 根据权利要求23所述的电容式麦克风，所述第三声学路径和/或所述第四声学路径中布置声延迟元件，所述声延迟元件被配置为延长对应声学路径的物理长度。
  39. 根据权利要求23所述的电容式麦克风，所述第三声学路径和/或所述第四声学路径均包括至少一个弯折段。
PCT/CN2024/091858 2023-05-10 2024-05-09 麦克风 Ceased WO2024230765A1 (zh)

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