WO2020029359A1 - 一种麦克风 - Google Patents

一种麦克风 Download PDF

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Publication number
WO2020029359A1
WO2020029359A1 PCT/CN2018/104431 CN2018104431W WO2020029359A1 WO 2020029359 A1 WO2020029359 A1 WO 2020029359A1 CN 2018104431 W CN2018104431 W CN 2018104431W WO 2020029359 A1 WO2020029359 A1 WO 2020029359A1
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WIPO (PCT)
Prior art keywords
magnet
diaphragm
magnetoresistive sensor
substrate
detection structure
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PCT/CN2018/104431
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English (en)
French (fr)
Inventor
邹泉波
冷群文
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歌尔股份有限公司
北京航空航天大学青岛研究院
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Publication of WO2020029359A1 publication Critical patent/WO2020029359A1/zh

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
    • H04R1/00—Details of transducers, loudspeakers or microphones
    • H04R1/08—Mouthpieces; Microphones; Attachments therefor

Definitions

  • the present invention relates to the field of measurement. More specifically, the present invention relates to a microphone capable of realizing sound-electric conversion.
  • the existing mainstream microphones are all condenser microphones that are tested by the principle of a flat capacitor.
  • the plate capacitor includes a substrate and a back plate and a diaphragm formed on the substrate. There is a gap between the back plate and the diaphragm, so that the back plate and the diaphragm constitute a flat plate type. Capacitor sensing structure.
  • the microphone In order to take full advantage of the mechanical sensitivity of the diaphragm, the microphone needs to design a huge back cavity with environmental pressure to ensure that the rigidity of the flowing air is far from the diaphragm.
  • the volume of the dorsal cavity is usually much larger than 1 mm 3 , for example, it is usually designed to be 1-15 mm 3 .
  • the microphone chip when packaged, its cavity needs to be opened. This limits the design of the smallest MEMS microphone package (> 3mm 3 ).
  • An object of the present invention is to provide a new technical solution for a microphone.
  • a microphone including a substrate and a diaphragm.
  • the middle position of the diaphragm is connected to the substrate through an elastic torsion beam, and the diaphragm forms a seesaw structure on the substrate.
  • the elastic torsion beam as the boundary, the two opposite sides of the membrane plate where the deflection movement occurs are respectively referred to as a first side and a second side, and a plurality of hollows for sound passage are provided at the positions of the second side of the membrane plate;
  • the diaphragm is configured to deflect using an elastic torsion beam as an axis when receiving a sound signal;
  • a first detection structure and a second detection structure are respectively formed on the first side and the second side of the diaphragm to characterize the deflection electrical signals on the corresponding side of the diaphragm; the first detection structure and the second detection structure constitute A differential structure;
  • the first detection structure and the second detection structure respectively include a magnet and a magnetoresistive sensor for cooperating with the magnet.
  • At least one of the magnetoresistive sensors in the first detection structure and the second detection structure is provided, and the magnetoresistive sensors in the first detection structure and the second detection structure constitute a Wheatstone bridge.
  • each magnetoresistive sensor corresponds to a magnet, and one of the magnet and the magnetoresistive sensor is disposed on a diaphragm, and the other is disposed on a substrate.
  • each magnetoresistive sensor corresponds to two magnets, which are respectively referred to as a first magnet and a second magnet, and the magnetoresistive sensors are disposed on the first magnet and the second magnet.
  • the magnetoresistive sensor In the common magnetic field formed by the two magnets; at the initial position, the magnetoresistive sensor is located at a position where the magnetic field direction of the first magnet is opposite to the magnetic field direction of the second magnet; the magnetoresistive sensor is configured during the deflection process of the diaphragm A change in a common magnetic field of the first magnet and the second magnet is induced to output a changed electric signal.
  • the magnetoresistive sensor receives the magnetic field of the first magnet, which is equal to the magnitude of the magnetic field received by the second magnet and has the opposite direction.
  • the first magnet and the second magnet are sequentially horizontally arranged on the membrane plate in the same manner as the direction of the magnetic poles, and the magnetoresistive sensor is disposed on the substrate at a position corresponding to the first magnet and the second magnet;
  • the first magnet and the second magnet are sequentially horizontally arranged on the substrate in the same manner as the direction of the magnetic poles, and the magnetoresistive sensor is disposed on a membrane plate at a position corresponding to the first magnet and the second magnet.
  • a load-bearing portion above the diaphragm is also provided, the magnetoresistive sensor is provided on the diaphragm, and the first magnet and the second magnet are respectively provided on the substrate and the bearing portion on both sides of the diaphragm. , And the first magnet and the second magnet are arranged in a manner in which the magnetic pole directions are opposite to each other.
  • the first magnet and the second magnet are symmetrical with respect to the magnetoresistive sensor.
  • the substrate has a first hollow cavity corresponding to the first side of the membrane plate, and a second hollow cavity corresponding to the second side of the membrane plate.
  • a substrate that closes the first hollow cavity and the second hollow cavity is further provided at an end of the substrate far from the membrane plate.
  • the first hollow cavity and the second hollow cavity are communicated together.
  • a driving device for adjusting the initial position of the diaphragm is also included.
  • the driving device is a piezoelectric sheet disposed at the position of the elastic torsion beam, and the piezoelectric sheet is configured to drive the elastic torsion beam to deform.
  • the driving device is an electrode sheet for providing a deflection electrostatic force to the membrane plate.
  • the microphone of the present invention when a sound signal is applied to the diaphragm, the first side of the diaphragm will respond to the sound signal, and the second side of the diaphragm is not sensitive to the sound signal because it has a cutout.
  • the incoming sound waves will tilt the diaphragm, causing a seesaw-like movement.
  • the degree of the deflection can be detected by the provided first detection structure and the second detection structure to characterize the sound signal.
  • the microphone of this structure has high sensitivity and is less affected by the volume of the back cavity. It can realize the thin and light development of the microphone and ensure the performance of the microphone.
  • FIG. 1 is a schematic structural diagram of a first embodiment of a microphone according to the present invention.
  • FIG. 2 is a schematic diagram of a microphone according to a second embodiment of the present invention.
  • FIG. 3 is a schematic structural diagram of a third embodiment of a microphone according to the present invention.
  • FIG. 4a is a coordinate diagram of a magnetoresistive sensor and two magnets in the embodiment shown in FIG. 2.
  • FIG. 4a is a coordinate diagram of a magnetoresistive sensor and two magnets in the embodiment shown in FIG. 2.
  • FIG. 4b is a simulation diagram of a magnetic field distribution in the embodiment shown in FIG. 2.
  • FIG. 4b is a simulation diagram of a magnetic field distribution in the embodiment shown in FIG. 2.
  • FIG. 4c is an enlarged view of the linear detection area of the magnetoresistive sensor in FIG. 4b.
  • FIG. 5 is a schematic structural diagram of a fourth embodiment of a microphone according to the present invention.
  • FIG. 6a is a coordinate diagram of a magnetoresistive sensor and two magnets in the embodiment shown in FIG. 5.
  • FIG. 6a is a coordinate diagram of a magnetoresistive sensor and two magnets in the embodiment shown in FIG. 5.
  • FIG. 6b is a simulation diagram of a magnetic field distribution in the embodiment shown in FIG. 5.
  • FIG. 6b is a simulation diagram of a magnetic field distribution in the embodiment shown in FIG. 5.
  • any specific value should be construed as exemplary only and not as a limitation. Therefore, other examples of the exemplary embodiments may have different values.
  • the present invention provides a microphone including a substrate 1 and a diaphragm connected to the substrate 1 through an elastic torsion beam 4.
  • the diaphragm is formed on the substrate 1 through the elastic torsion beam 4. Seesaw structure.
  • the substrate 1 of the present invention may be made of single crystal silicon, and the substrate 1 may have one hollow cavity; in another embodiment of the present invention, it may also have two hollow cavities, which are denoted as a first hollow cavity 11 and a second cavity, respectively. Hollow cavity 12.
  • a support substrate 5 may also be formed in the middle region of the substrate 1, and the support substrate 5 and the substrate 1 may be integrated. For example, a bulk silicon etching method may be used to form a first silicon substrate on the substrate 1 to separate the first substrate.
  • the supporting substrate 5 of the hollow cavity 11 and the second hollow cavity 12 will not be described in detail here.
  • the membrane plate may be connected to the supporting substrate 5 through elastic torsion beams 4 located on opposite sides thereof, or connected to the anchor points of the supporting substrate 5.
  • the elastic torsion beam 4 can be disposed in the middle region of the membrane plate, for example, and after being connected through the elastic torsion beam 4, the membrane plate can be deflected like a seesaw on the substrate 1 under the action of the elastic torsion beam 4.
  • the elastic torsion beam 4 can be provided in the membrane plate, for example, a central hole can be formed in the middle region of the membrane plate.
  • One end of the elastic torsion beam can be connected to the inner wall of the central hole position of the membrane plate, and the other end is connected to the substrate 1
  • the support substrate 5 can also realize the seesaw-type movement of the membrane plate.
  • the film plate of the present invention may be made of polysilicon, single crystal silicon, or other materials well known to those skilled in the art.
  • the membrane needs to have sufficient hardness to avoid deformation of the membrane itself. Those skilled in the art can obtain a membrane that meets the requirements by controlling the thickness of the membrane, which is not described in detail here.
  • the two opposite sides of the diaphragm are respectively referred to as the first side 2 of the diaphragm and the second side 3 of the diaphragm.
  • Hollow-outs 10 are provided at the position of the second side 3 of the membrane plate, and a plurality of hollow-outs 10 can be provided in a matrix arrangement.
  • the plurality of hollows 10 can reduce the mass of the second side 3 of the diaphragm, so that the mass of the first side 2 is greater than the mass of the second side 3.
  • the hollow 10 can also pass sound.
  • the elastic torsion beam 4 is similar to a seesaw-type deflection of the shaft. That is, the first side 2 of the diaphragm will move in a direction close to the substrate 1, and the second side 3 of the diaphragm will move in a direction away from the substrate 1.
  • the diaphragm When the external sound acts on the second side 3 of the diaphragm, since a plurality of hollows 10 are provided on the second side 3, the sound will pass through the second side 3 of the diaphragm, so the second side 3 of the diaphragm will not Under the effect of sound pressure, that is, the second side 3 of the diaphragm is not sensitive to sound, and the diaphragm will not deflect. At this time, even if the masses on both sides of the diaphragm are equal, the diaphragm will be deflected by the sound pressure difference.
  • the first side 2 of the membrane plate may correspond to the first hollow cavity 11, and the second side 3 of the membrane plate may correspond to the second hollow cavity 12.
  • the arrangement of the first hollow cavity 11 and the second hollow cavity 12 makes it possible to reduce the resistance to air when the membrane is deflected, and to increase the sensitivity of the membrane deflection.
  • the first hollow cavity 11 and the second hollow cavity 12 may also communicate with each other to equalize the air resistance experienced by both sides of the membrane plate during deflection, which will not be described in detail here.
  • a substrate 15 that closes the first hollow cavity 11 and the second hollow cavity 12 is further provided at an end of the substrate 1 away from the membrane plate, as shown in FIG. 3.
  • the base plate 15 closes the first hollow cavity 11 and the second hollow cavity 12, the first hollow cavity 11 and the second hollow cavity 12 communicate with each other, and the second hollow cavity 12 communicates with the outside through the hollow 10 on the second side 3 of the membrane plate .
  • the substrate 15 may be a circuit board, which is not described in detail here.
  • the supporting substrate 5 may extend to two opposite sides of the substrate 1 to space the first hollow cavity 11 and the second hollow cavity 12 apart. At this time, the communication between the two hollow cavities may depend on a through hole provided on the support substrate 5.
  • the membrane plate is connected to the supporting substrate 5 by means of an elastic torsion beam, a gap is left between the membrane plate and the supporting substrate 5, and the two hollow cavities are communicated through the gap.
  • the deflection information on both sides of the diaphragm can be detected, and the sound signal can be characterized according to the output electrical signal.
  • a first detection structure and a second detection structure are formed on the first side 2 and the second side 3 of the membrane to characterize the deflection electrical signal on the corresponding side of the membrane; the first detection structure and the second detection structure constitute Differential structure.
  • the microphone of the present invention when a sound signal is applied to the diaphragm, the first side of the diaphragm will respond to the sound signal, and the second side of the diaphragm is not sensitive to the sound signal because it has a cutout.
  • the incoming sound waves will tilt the diaphragm, causing a seesaw-like movement.
  • the degree of the deflection can be detected by the provided first detection structure and the second detection structure to characterize the sound signal.
  • the microphone of this structure has high sensitivity and is less affected by the volume of the back cavity. It can realize the thin and light development of the microphone and ensure the performance of the microphone.
  • the first detection structure and the second detection structure respectively include a magnet and a magnetoresistive sensor for cooperating with the magnet.
  • the magnetoresistive sensor can output a changed electrical signal.
  • the magnetoresistive sensor can be selected from, for example, a giant magnetoresistive sensor (GMR) or a tunnel magnetoresistive sensor (TMR).
  • GMR giant magnetoresistive sensor
  • TMR tunnel magnetoresistive sensor
  • the first detection structure includes a magnet a6 provided on the first side 2 of the diaphragm and a magnetoresistive sensor a7 provided on the substrate 1.
  • the magnet 6 may be a magnetic thin film.
  • the magnetic film may be directly made of a magnetic material, or may be magnetized after the film is formed.
  • the magnetic thin film may be made of CoCrPt or CoPt.
  • the magnet a6 may be disposed on the side of the first side 2 of the diaphragm away from the magnetoresistive sensor a7, or on the side near the magnetoresistive sensor a7, or in the structure of the diaphragm, which will not be described in detail here.
  • a magnetoresistive sensor a is provided on the substrate 1. Specifically, at the time of production, an insulating layer can be deposited on the substrate 1 first, and then a magnetoresistive sensor a7 is formed on the insulating layer. In order to protect the magnetoresistive sensor a7, a layer of magnetic The passivation layer covered by the resistive sensor a, the insulating layer and the passivation layer can be made of materials well known to those skilled in the art, and will not be described in detail here.
  • a lead portion may be provided to be connected with the magnetoresistive sensor a7, and finally a pad 14 is formed at a corresponding position on the outside of the microphone, which is not described in detail here.
  • the magnet a6 on the first side 2 is close to the magnetoresistive sensor a7, so that the magnetoresistive sensor a7 can sense the change of the magnetic field and the output changes.
  • the electrical signal realizes the conversion of sound and electricity.
  • the second detection structure includes a magnet b8 disposed on the second side 3 of the diaphragm and a magnetoresistive sensor b9 disposed on the substrate 1, the magnet b8, the magnetoresistive sensor b9, the magnetoresistive sensor a7, and the magnet a
  • the setting method of 6 can be the same, which is not described in detail here.
  • Magnetoresistive sensors a7 and b9 can be connected together to form a Wheatstone half-bridge circuit, so that the entire microphone can output electrical signals that characterize sound change information.
  • the magnetoresistive sensor a7 and the magnetoresistive sensor b9 can also be arranged on the diaphragm, and the magnets a6 and b8 are arranged on the substrate, which can also realize the detection of electrical signals. , Will not be described in detail here. It should be noted that, when the magnetoresistive sensor is disposed on the diaphragm, in order to avoid the lead from affecting the deflection of the diaphragm, the lead portion can be led out through the position of the elastic torsion beam 4, which is not described in detail here.
  • a plurality of magnetoresistive sensors a7 and b9 may be provided, for example, two magnetoresistive sensors a7 and two magnetoresistive sensors b9 are provided. Each magnetoresistive sensor corresponds to a magnet. Two magnetoresistive sensors a7 and two magnetoresistive sensors b9 can form a Wheatstone full-bridge circuit, so that the microphone can output an electric signal characterizing sound change information.
  • the detection range of the magnetoresistive sensor may be very low due to the narrow linear range of the magnetoresistive sensor.
  • the first detection structure and the second detection structure are selected from a dual magnet structure.
  • the structures of the first detection structure and the second detection structure are the same. Now, taking the first detection structure as an example, the dual magnet structure is described in detail.
  • the first detection structure and the second detection structure each include a first magnet, a second magnet, and a magnetoresistive sensor disposed in a common magnetic field formed by the first magnet and the second magnet.
  • the first magnet and the second magnet are arranged correspondingly so that the magnetic fields of the two magnets interact with each other.
  • the magnetoresistive sensor simultaneously senses the magnetic fields of the first magnet and the second magnet, so that the magnetoresistive sensor can sense the change in the common magnetic field of the first magnet and the second magnet during the vibration of the diaphragm, thereby outputting a changed electrical signal.
  • the magnetic fields of the two magnets are opposite to each other.
  • the common magnetic field of the two magnets received by the magnetoresistive sensor is weakened compared to a single magnet.
  • the initial position of the magnetoresistive sensor is a position where the magnetic field of the first magnet is opposite to that of the second magnet.
  • the magnetoresistive sensor receives the magnetic field of the first magnet, and the magnetic field of the magnetoresistive sensor has the same magnitude as the magnetic field of the second magnet, and the directions are opposite. That is to say, at this position, the magnetoresistive sensor is subjected to the same magnitude of the magnetic field of the two magnets, and the directions are opposite. At this time, the common magnetic field of the two magnets received by the magnetoresistive sensor is zero.
  • the first magnet 60 and the second magnet 61 are disposed at two positions on the first side of the diaphragm.
  • the first magnet 60 and the second magnet 61 may be made of a magnetic film, and the magnetic film may be directly made of a magnetic material. This film may be magnetized after the film is formed.
  • the magnetic thin film may be made of CoCrPt or CoPt.
  • the first magnet 60 and the second magnet 61 may be formed on the first side 2 of the diaphragm by deposition or other means well known to those skilled in the art.
  • the first magnet 60 and the second magnet 61 can also be protected by an insulating layer and a passivation layer, which will not be described in detail here.
  • the first magnet 60 and the second magnet 61 are disposed adjacent to each other, and are sequentially horizontally arranged on the first side 2 of the membrane plate in the same manner in the direction of the magnetic poles. For example, at the time of fabrication, two independent films are formed first, and then the two films are magnetized simultaneously. After the magnetization, referring to the view direction of FIG. 2, the upper side of the first magnet 60 and the second magnet 61 are both N poles and the lower side are S poles; vice versa.
  • the magnetoresistive sensor 70 is provided on the substrate 1 at a position corresponding to the first magnet 60 and the second magnet 61.
  • the first side 2 of the diaphragm is subjected to external sound pressure, the first side 2 of the diaphragm is deflected toward the substrate 1.
  • the first magnet 60 and the second magnet 61 on the first side 2 of the diaphragm are close to the magnetic field.
  • Resistance sensor 70 so that the magnetoresistive sensor 70 can sense the change of the common magnetic field of the first magnet 60 and the second magnet 61, thereby outputting a changed electrical signal, and achieving the acoustic-electric conversion.
  • the magnetoresistive sensor 70 may be disposed on a center line of the first magnet 60 and the second magnet 61.
  • the magnetic field directions of the first magnet 60 and the second magnet 61 are returned from the N pole to the S pole. Therefore, at a certain position on the center line of the first magnet 60 and the second magnet 61, the magnetic directions of the first magnet 60 and the second magnet 61 are opposite and the magnetic field strength is approximately the same. This position is the initial position of the magnetoresistive sensor 70.
  • the magnetoresistive sensor 70 Since the magnetoresistive sensor 70 is simultaneously subjected to the action of two magnets, the two magnets cooperate to reduce the strength of the entire magnetic field, and increase the sensitivity of the magnetic field change within the linear range of the magnetoresistive sensor 70, ultimately increasing the magnetoresistance The detection sensitivity of the sensor 70.
  • FIG. 4 a shows a coordinate diagram of the distribution of two magnets and a magnetoresistive sensor in the embodiment shown in FIG. 2.
  • the origin position is located at the center of the two magnets.
  • 4b and 4c show simulation diagrams of magnetic field distribution in the embodiment shown in FIG. 2.
  • the size of both magnets is 6 ⁇ m * 4 ⁇ m * 0.5 ⁇ m, and the gap between the two magnets is 2 ⁇ m.
  • the abscissa in Fig. 4b and Fig. 4c represent the vertical distance z (m) of the magnetoresistive sensor relative to the center position of the two magnets, and the ordinate represents the magnetic field strength B (T) and the magnetic field change gradient dB / dx (T / m) .
  • Line a1 in the figure represents the change curve of B (T) with z (m)
  • line b1 represents the change curve of magnetic field change gradient dB / dx (T / m) with z (m
  • the magnetic field strength of the initial position of the magnetoresistive sensor 70 is 0, that is, the position where B (T) in line a1 is 0.
  • z (m) is about 4 ⁇ m.
  • the distance between the center of each magnet is 4 ⁇ m.
  • the value of the line b1 is approximately 2.0 * 10 5 T / m. That is, the gradient of the magnetic field change at this position is 2.0 * 10 5 T / m.
  • the area of the line b1 on the left and right sides of the initial position is relatively flat, which ensures that the magnetoresistive sensor 70 can be located in its linear detection area.
  • a plurality of magnetoresistive sensors in the first detection structure may be provided.
  • two magnetoresistive sensors are provided, each of which corresponds to two Magnets.
  • the first detection structure and the second detection structure have the same structure and are symmetrically arranged, so that the two detection structures can form a Wheatstone full-bridge circuit, so as to ensure that the microphone can output an electric signal representing the sound change information.
  • the first magnet 60 and the second magnet 61 may also be disposed on the substrate 1, and the magnetoresistive sensor 70 may be disposed at a corresponding position on the first side 2 of the diaphragm.
  • the position of the driving magnetoresistive sensor 70 changes, and the same effect can be achieved, which is not described in detail here.
  • the magnetoresistive sensor is disposed on the diaphragm, in order to avoid the lead from affecting the deflection of the diaphragm, the lead portion can be led out through the position of the elastic torsion beam 4, which is not described in detail here.
  • a bearing portion 15 is further provided above the membrane plate, as shown in FIG. 5.
  • the bearing portion 15 can be directly or indirectly connected to the substrate 1 through a space portion, and there is a certain gap between the bearing portion 15 and the membrane plate, so that the bearing portion 15 does not hinder the deflection of the membrane plate.
  • the first magnet 63 and the second magnet 62 of the first detection structure are respectively disposed on the substrate 1 and the bearing portion 15.
  • the first magnet 63 and the second magnet 62 may use a magnetic film, and the magnetic film may be directly made of a magnetic material, or may be magnetized after forming the film.
  • the magnetic thin film may be made of CoCrPt or CoPt.
  • the first magnet 63 and the second magnet 62 may be respectively provided with a protective structure, for example, covered by an insulating layer or a passivation layer, and the like is not described in detail here.
  • the first magnet 63 and the second magnet 62 are respectively arranged on the substrate 1 and the supporting portion 15 in a manner that the magnetic pole directions are opposite to each other. Referring to the view direction of FIG. 5, when the left side of the first magnet 63 is the N pole and the right side is the S pole, the left side of the second magnet 62 is the S pole and the right side is the N pole;
  • the magnetoresistive sensor 71 is disposed on the first side 2 of the membrane plate at a position corresponding to the first magnet 63 and the second magnet 62.
  • a lead portion is provided on the board, one end of the lead portion is connected to the magnetoresistive sensor 71, and the other end extends on the membrane plate and is led out through the position of the elastic torsion beam 4, which is not described in detail here.
  • the magnetoresistive sensor 71 on the first side 2 of the diaphragm is close to the first magnet 63 And away from the second magnet 62, so that the magnetoresistive sensor 71 can sense the change of the common magnetic field of the first magnet 63 and the second magnet 62, and output a changed electric signal, thereby realizing the conversion of acoustic electricity.
  • the first magnet 63 and the second magnet 62 are preferably symmetrical with respect to the magnetoresistive sensor 71, and this position of the magnetoresistive sensor 71 is its initial position.
  • the magnetic field directions of the first magnet 63 and the second magnet 62 are both From N pole to S pole.
  • This vertical arrangement makes the magnetic field directions of the first magnet 63 and the second magnet 62 opposite to each other and the magnetic field strengths to be approximately the same at the positions of the centers of the first magnet 63 and the second magnet 62.
  • the magnetoresistive sensor 71 When the magnetoresistive sensor 71 deflects with the diaphragm, the magnetoresistive sensor 71 will use the center position as an initial position to perform up and down vibration. At this initial position, the magnetoresistive sensor 71 is subjected to the same magnitude of the magnetic fields of the two magnets, and their directions are opposite. For example, when the first side 2 of the diaphragm is deflected toward the bearing portion 15, the magnetoresistive sensor 71 is close to the second magnet 62 and away from the first magnet 63. According to the characteristics of the magnet, it can be known that the magnetoresistive sensor 71 is subjected to the second magnet 62. The influence of is greater than that by the first magnet 63; and vice versa.
  • the magnetoresistive sensor 71 Since the magnetoresistive sensor 71 is simultaneously subjected to the action of two magnets, the two magnets cooperate to reduce the strength of the entire magnetic field, and increase the sensitivity of the magnetic field change within the linear range of the magnetoresistive sensor 71, and finally increase the magnetoresistance Detection sensitivity of the sensor 71.
  • Fig. 6a shows a coordinate diagram of the distribution of two magnets and a magnetoresistive sensor in the embodiment shown in Fig. 5.
  • the origin position is located at the center position of the lower magnet (first magnet 63).
  • Fig. 6b shows a simulation diagram of a magnetic field distribution in the embodiment shown in Fig. 5.
  • the size of both magnets is 2 ⁇ m * 1 ⁇ m * 0.1 ⁇ m, and the distance between the two magnets is 2 ⁇ m.
  • the abscissa in FIG. 6b represents the vertical distance z (m) of the magnetoresistive sensor relative to the center position of the lower magnet, and the ordinate represents the magnetic field strength Bx (T) and the magnetic field change gradient dB / dz (T / m).
  • Line a2 in the figure represents the change curve of Bx (T) with z (m)
  • line b2 represents the change curve of the magnetic field change gradient dB / dz (T / m) with z (m).
  • the magnetic field strength of the initial position of the magnetoresistive sensor 71 is 0, that is, the position where Bx (T) in line a2 is 0. At this time, z (m) is about 1 ⁇ m (1.0E-06).
  • the magnetoresistive sensor 71 is positioned at a distance of 1 ⁇ m from the center of the lower magnet (the first magnet 63). At this initial position, the value of the line b2 is approximately 1.6 * 10 6 T / m. That is, the gradient of magnetic field change at this position is 1.6 * 10 6 T / m. Compared with the traditional single magnet structure, the sensitivity to magnetic field changes is greatly improved.
  • the area of the line b2 on the left and right sides of the initial position is relatively flat, which ensures that the magnetoresistive sensor 71 can be located in its linear detection area.
  • a plurality of magnetoresistive sensors in the first detection structure may be provided.
  • two magnetoresistive sensors are provided in the first detection structure and the second detection structure, and each magnetoresistive sensor is provided.
  • the first detection structure and the second detection structure have the same structure and are symmetrically arranged, so that the two detection structures can form a Wheatstone full-bridge circuit, so as to ensure that the microphone can output an electric signal representing the sound change information.
  • the initial position of the diaphragm needs to be calibrated. This is because when manufacturing and assembling, it is unavoidable that the error will affect the initial position. Therefore, a driving device needs to be provided to adjust the initial position of the diaphragm.
  • the driving device may be, for example, a piezoelectric sheet 16 disposed at a position of the elastic torsion beam 4, and the piezoelectric sheet 16 is configured to drive the elastic torsion beam 4 to deform.
  • the piezoelectric sheet 16 may be made of AlN, PZT, or ZnO materials, which are well known to those skilled in the art.
  • the piezoelectric sheet 16 drives the elastic torsion beam to deform to a certain extent, thereby achieving the purpose of adjusting the initial position of the diaphragm.
  • the driving device may be an electrode sheet for providing a deflection electrostatic force to the membrane plate.
  • an electrostatic force can be applied to the first side or the second side of the diaphragm to cause a certain deflection of the diaphragm, and the position adjustment is also achieved.
  • a top-mounting (TOP type) or a bottom-mounting (Bottom-type) structure may be adopted.
  • the sound hole of the packaging structure may be the same as the first of the diaphragm.
  • the side 2 is directly opposite or close to each other, so that the sound can directly act on the first side 2 of the diaphragm, which is not described in detail here.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Acoustics & Sound (AREA)
  • Signal Processing (AREA)
  • Pressure Sensors (AREA)
  • Measuring Fluid Pressure (AREA)

Abstract

本发明公开了一种麦克风，膜板的中部位置通过弹性扭梁连接在衬底上，形成了跷跷板结构；在膜板第二侧的位置设置有多个供声音穿过的镂空；在所述膜板的第一侧、第二侧还分别形成了用于表征膜板相应侧偏转电信号的第一检测结构、第二检测结构。本发明的麦克风，灵敏度高，且受后腔容积的影响较低，可以实现麦克风的轻薄化发展并保证麦克风的性能。

Description

一种麦克风 技术领域
本发明涉及测量领域，更准备地说，本发明涉及一种可以实现声电转换的麦克风。
背景技术
现有主流的麦克风，均是通过平板电容器的原理进行检测的电容式麦克风。在麦可风的结构中，平板电容器包括衬底以及形成在衬底上的背极板、振膜，背极板与振膜之间具有间隙，使得背极板、振膜构成了平板式的电容器感测结构。
为了充分利用振膜的机械灵敏度，麦克风需要设计一个具有环境压力的巨大后腔，以确保流动空气的刚性远远振膜。背腔的容积通常远大于1mm 3，例如通常设计为1-15mm 3。而且麦克风芯片在封装的时候，需要开放其腔体。这就限制了MEMS麦克风最小尺寸封装的设计(>3mm 3)。
这是由于如果后腔容积过小，则不利于空气的流通，这种空气的刚性则会大大降低振膜的机械灵敏度。另外，为了均压，背极板上通常会设计密集的通孔，由于空气粘度造成的间隙或穿孔中的空气流动阻力成为MEMS麦克风噪声的主导因素，从而限制了麦克风的高信噪比性能。
发明内容
本发明的一个目的是提供一种麦克风的新技术方案。
根据本发明的第一方面，提供了一种麦克风，包括衬底、膜板，所述膜板的中部位置通过弹性扭梁连接在衬底上，所述膜板在衬底上形成了跷跷板结构；以弹性扭梁为界，所述膜板发生偏转运动的相对两侧分别记为第一侧、第二侧，其中在膜板第二侧的位置设置有多个供声音穿过的镂空；所述膜板被配置为受到声音信号时以弹性扭梁为轴发生偏转；
在所述膜板的第一侧、第二侧还分别形成了用于表征膜板相应侧偏转电信号的第一检测结构、第二检测结构；所述第一检测结构和第二检测结构构成了差分结构；
所述第一检测结构、第二检测结构分别包含磁体以及用于与磁体配合在一起的磁阻传感器。
可选地，第一检测结构、第二检测结构中的磁阻传感器分别至少设置有一个，第一检测结构、第二检测结构中的磁阻传感器构成了惠斯通电桥。
可选地，每个磁阻传感器对应一个磁体，所述磁体和磁阻传感器中的一个设置在膜板上，另一个设置在衬底上。
可选地，所述第一检测结构、第二检测结构的结构相同，每个磁阻传感器对应两个磁体，分别记为第一磁体、第二磁体，磁阻传感器设置在第一磁体、第二磁体形成的共同磁场中；初始位置时，所述磁阻传感器位于第一磁体的磁场方向与第二磁体的磁场方向相反的位置；所述磁阻传感器被配置为在膜板的偏转过程中感应第一磁体、第二磁体共同磁场的变化而输出变化的电信号。
可选地，初始位置时，所述磁阻传感器受到第一磁体的磁场，与受到第二磁体的磁场大小相等，方向相反。
可选地，所述第一磁体、第二磁体以磁极方向相同的方式依次水平布置在膜板上，所述磁阻传感器设置在衬底上与第一磁体、第二磁体相对应的位置；
或者，所述第一磁体、第二磁体以磁极方向相同的方式依次水平布置在衬底上，所述磁阻传感器设置在膜板上与第一磁体、第二磁体相对应的位置。
可选地，还设置有位于膜板上方的承载部，所述磁阻传感器设置在膜板上，所述第一磁体、第二磁体分别设置在位于振膜两侧的衬底、承载部上，且第一磁体、第二磁体的以磁极方向相反的方式进行布置。
可选地，所述第一磁体、第二磁体相对于磁阻传感器对称。
可选地，所述衬底上具有与膜板第一侧对应的第一中空腔，以及与膜板第二侧对应的第二中空腔。
可选地，在所述衬底远离膜板的一端还设置有将第一中空腔、第二中空腔封闭的基板。
可选地，所述第一中空腔、第二中空腔连通在一起。
可选地，还包括调节膜板初始位置的驱动装置。
可选地，所述驱动装置为设置在弹性扭梁位置的压电片，所述压电片被配置为驱动弹性扭梁变形。
可选地，所述驱动装置为用于给膜板提供偏转静电力的电极片。
根据本发明的麦克风，当声音信号作用到膜板上时，膜板第一侧会响应该声音信号，而膜板的第二侧由于具有镂空，因此对声音信号不敏感。此时进入的声波会使膜板倾斜，从而发生跷跷板式的运动。通过设置的第一检测结构和第二检测结构可以检测该偏转的程度，以表征声音信号。这种结构的麦克风，灵敏度高，且受后腔容积的影响较低，可以实现麦克风的轻薄化发展并保证麦克风的性能。
通过以下参照附图对本发明的示例性实施例的详细描述，本发明的其它特征及其优点将会变得清楚。
附图说明
被结合在说明书中并构成说明书的一部分的附图示出了本发明的实施例，并且连同其说明一起用于解释本发明的原理。
图1是本发明麦克风第一实施方式的结构示意图。
图2是本发明麦克风第二实施方式中原理图。
图3是本发明麦克风第三实施方式的结构示意图。
图4a是图2所示实施例中磁阻传感器与两个磁体的坐标图。
图4b是图2所示实施例中磁场分布的仿真图。
图4c是图4b中示意磁阻传感器线性检测区域的放大图。
图5是本发明麦克风第四实施方式的结构示意图。
图6a是图5所示实施例中磁阻传感器与两个磁体的坐标图。
图6b是图5所示实施例中磁场分布的仿真图。
具体实施方式
现在将参照附图来详细描述本发明的各种示例性实施例。应注意到：除非另外具体说明，否则在这些实施例中阐述的部件和步骤的相对布置、数字表达式和数值不限制本发明的范围。
以下对至少一个示例性实施例的描述实际上仅仅是说明性的，决不作为对本发明及其应用或使用的任何限制。
对于相关领域普通技术人员已知的技术、方法和设备可能不作详细讨论，但在适当情况下，所述技术、方法和设备应当被视为说明书的一部分。
在这里示出和讨论的所有例子中，任何具体值应被解释为仅仅是示例性的，而不是作为限制。因此，示例性实施例的其它例子可以具有不同的值。
应注意到：相似的标号和字母在下面的附图中表示类似项，因此，一旦某一项在一个附图中被定义，则在随后的附图中不需要对其进行进一步讨论。
参考图1、图2，本发明提供了一种麦克风，其包括衬底1以及通过弹性扭梁4连接在衬底1上的膜板，膜板通过弹性扭梁4在衬底1上形成了跷跷板结构。
本发明的衬底1可以采用单晶硅材质，衬底1可以具有一个中空腔；在本发明另一个实施方式中，也可以具有两个中空腔，分别记为第一中空腔11、第二中空腔12。在衬底1的中部区域还可形成有支撑衬底5，该支撑衬底5与衬底1可以是一体的，例如可通过体硅刻蚀的方式在衬底1上形成用于分隔第一中空腔11、第二中空腔12的支撑衬底5，在此不再具体说明。
膜板可通过位于其相对两侧的弹性扭梁4连接在支撑衬底5上，或者连接在支撑衬底5的锚点上。该弹性扭梁4例如可设置在膜板的中部区域，通过该弹性扭梁4连接后，使得在弹性扭梁4的作用下，膜板可以在衬底1上发生类似跷跷板式的偏转。其中，弹性扭梁4可以设置在膜板中，例如可在膜板的中部区域形成中心孔，弹性扭梁的一端可以连接在膜板中心孔位置的内壁上，另一端连接在衬底1或者支撑衬底5上，同样可以实现 膜板做跷跷板式的运动。
本发明的膜板可以采用多晶硅、单晶硅或者本领域技术人员所熟知的其它材质。该膜板需要有足够的硬度，以避免膜板自身发生形变。本领域的技术人员可通过对膜板厚度的控制是获得满足需求的膜板，在此不再具体说明。
以弹性扭梁4为界，膜板相对的两侧分别记为膜板的第一侧2以及膜板的第二侧3。其中在膜板第二侧3的位置设置有镂空10，镂空10可以设置多个，呈矩阵排列。该多个镂空10可以减轻膜板第二侧3的质量，以使得第一侧2的质量大于第二侧3的质量。另外，该镂空10还可以供声音穿过。
由于膜板第一侧2、第二侧3的质量不相等，这就使得膜板两侧的力矩不平衡，当膜板的第一侧2受到外界的声音信号时，使得整个膜板会以弹性扭梁4为轴发生类似跷跷板式的偏转。即膜板的第一侧2会朝向接近衬底1的方向运动，膜板的第二侧3会朝向远离衬底1的方向运动。
当外界的声音作用在膜板的第二侧3后，由于在第二侧3上设置多个镂空10，声音会穿过膜板的第二侧3，因此膜板的第二侧3不会受到声压的作用，即膜板的第二侧3对声音不敏感，膜板不会发生偏转。此时，即使膜板两侧的质量相等，膜板也会在声压差的作用下发生偏转。
膜板的第一侧2可以与第一中空腔11对应，膜板的第二侧3可以与第二中空腔12相对应。第一中空腔11、第二中空腔12的设置，使得减少膜板偏转时对空气的阻力，提高膜板偏转的灵敏度。优选的是，第一中空腔11和第二中空腔12也可以连通在一起，以均衡膜板两侧在偏转时受到的空气阻力，在此不再具体说明。
当然，在本发明另一个实施方式中，在衬底1远离膜板的一端还设置有将第一中空腔11、第二中空腔12封闭的基板15，参考图3。基板15将第一中空腔11、第二中空腔12封闭住，第一中空腔11、第二中空腔12连通起来，第二中空腔12通过膜板第二侧3上的镂空10与外界连通。基板15可以是电路板，在此不再具体说明。
具体地，例如支撑衬底5可以延伸至衬底1相对的两侧，以将第一中 空腔11和第二中空腔12间隔开。此时两个中空腔的连通可以依靠设置在支撑衬底5上的通孔。也可以是，当膜板依靠弹性扭梁连接在支撑衬底5上后，膜板与支撑衬底5之间会留有间隙，通过该间隙实现两个中空腔的连通。
在膜板的两侧设置偏转的检测结构后，可以检测到膜板两侧的偏转信息，并根据输出的电信号来表征声音信号。
例如，在膜板的第一侧2、第二侧3分别形成用于表征膜板相应侧偏转电信号的第一检测结构、第二检测结构；该第一检测结构和第二检测结构构成了差分结构。
本发明的麦克风，当声音信号作用到膜板上时，膜板第一侧会响应该声音信号，而膜板的第二侧由于具有镂空，因此对声音信号不敏感。此时进入的声波会使膜板倾斜，从而发生跷跷板式的运动。通过设置的第一检测结构和第二检测结构可以检测该偏转的程度，以表征声音信号。这种结构的麦克风，灵敏度高，且受后腔容积的影响较低，可以实现麦克风的轻薄化发展并保证麦克风的性能。
在本发明一个具体的实施方式中，第一检测结构、第二检测结构分别包含磁体以及用于与磁体配合在一起的磁阻传感器。通过磁阻传感器与磁体之间距离的变化可以使磁阻传感器输出变化的电信号。磁阻传感器可以选用例如巨磁阻传感器(GMR)或者隧道磁阻传感器(TMR)。通过采用高灵敏度的巨磁阻传感器(GMR)或者隧道磁阻传感器(TMR)来获得检测的电信号，可以保证麦克风的声学性能。
在本发明一个具体的实施方式中，参考图1，第一检测结构包括设置在膜板第一侧2的一个磁体a 6以及设置在衬底1上的一个磁阻传感器a 7。磁体a 6可以是磁性薄膜。磁性薄膜可以直接采用磁性材质，也可以是形成薄膜后对该薄膜进行充磁。在本发明一个具体的实施方式中，磁性薄膜可以采用CoCrPt或者CoPt材质。
磁体a 6可以设置在膜板第一侧2上远离磁阻传感器a 7的一面，或者靠近磁阻传感器a 7的一面，或者是设置在膜板的结构内，在此不再具体说明。
磁阻传感器a 7设置在衬底1上。具体在制作的时候，可以首先在衬底1上沉积一层绝缘层，然后在绝缘层上形成磁阻传感器a 7，为了保护磁阻传感器a 7，还可以在绝缘层上沉积一层将磁阻传感器a 7覆盖住的钝化层，绝缘层、钝化层可以选用本领域技术人员所熟知的材质，在此对其不再具体说明。
为了将磁阻传感器a 7的电信号引出，可以设置引线部与磁阻传感器a7连接在一起，并最终在麦克风外侧相应的位置形成焊盘14，在此不再具体说明。
当膜板的第一侧2朝向衬底1的方向偏转时，此时第一侧2上的磁体a 6靠近磁阻传感器a 7，从而使得磁阻传感器a 7可以感应磁场的变化，输出变化的电信号，实现了声电的转换。
第二检测结构包括设置在膜板第二侧3的一个磁体b 8以及设置在衬底1上的一个磁阻传感器b 9，磁体b 8、磁阻传感器b 9与磁阻传感器a7、磁体a 6的设置方式可以是一样的，在此不再具体说明。当膜板的第二侧3朝远离衬底1的方向偏转时，此时第二侧2上的磁体b 8远离磁阻传感器b 9，从而使得磁阻传感器b 9可以感应磁场的变化，输出变化的电信号，实现了声电的转换。
磁阻传感器a 7与磁阻传感器b 9可以连接在一起，形成惠斯通半桥电路，使得整个麦克风可以输出表征声音变化信息的电信号。
当然，对于本领域的技术人员而言，磁阻传感器a 7、磁阻传感器b 9也可以设置在膜板上，磁体a 6、磁体b 8设置在衬底上，同样可以实现电信号的检测，在此不再具体说明。需要注意的是，当磁阻传感器设置在膜板上时，为了避免引线对膜板的偏转带来影响，引线部可以经过弹性扭梁4的位置引出，在此不再具体说明。
在本发明另一个具体的实施方式中，磁阻传感器a 7、磁阻传感器b 9可以各设置有多个，例如分别设置了两个磁阻传感器a 7、两个磁阻传感器b 9。每个磁阻传感器对应一个磁体。两个磁阻传感器a 7、两个磁阻传感器b 9可以构成惠斯通全桥电路，使得麦克风可以输出表征声音变化信息的电信号。
单磁体、单磁阻传感器结构中，可能会由于磁阻传感器的线性范围很窄，造成磁阻传感器的检测灵敏度很低。
因此在本发明一个具体的实施方式中，第一检测结构、第二检测结构选用双磁体结构。第一检测结构、第二检测结构的结构相同，现以第一检测结构为例，对双磁体结构进行详尽的描述。
第一检测结构、第二检测结构均包括第一磁体、第二磁体，以及设置在第一磁体、第二磁体形成共同磁场中的磁阻传感器。第一磁体、第二磁体对应布置在一起，使得二者的磁场相互作用在一起。磁阻传感器同时感应第一磁体、第二磁体的磁场，从而使得磁阻传感器在振膜的振动过程中可以感应第一磁体、第二磁体共同磁场的变化，从而输出变化的电信号。
在第一磁体、第二磁体的共同磁场中，某些位置时，两个磁体的磁场方向相反，在该位置，磁阻传感器受到的两个磁体的共同磁场较单个磁体而言会减弱。磁阻传感器初始位置即位于第一磁体的磁场与第二磁体的磁场方向相反的位置。
优选的是，初始位置时，所述磁阻传感器受到第一磁体的磁场，与受到第二磁体的磁场大小相等，方向相反。也就是说，在该位置时，磁阻传感器受到两个磁体的磁场大小相等，方向相反。此时，磁阻传感器受到的两个磁体的共同磁场为零。
双磁体实施例1
具体地，参考图2，第一磁体60、第二磁体61设置在膜板的第一侧2位置，第一磁体60、第二磁体61可以采用磁性薄膜，磁性薄膜可以直接采用磁性材质，也可以是形成薄膜后对该薄膜进行磁化。在本发明一个具体的实施方式中，磁性薄膜可以采用CoCrPt或者CoPt材质。
该第一磁体60、第二磁体61可以通过沉积或者本领域技术人员所熟知的其它手段形成在膜板的第一侧2。还可以通过绝缘层、钝化层对第一磁体60、第二磁体61进行保护，在此对其不再具体说明。
第一磁体60、第二磁体61相邻设置，且以磁极方向相同的方式依次水平布置在膜板的第一侧2上。例如在制作的时候，先形成两个独立的薄 膜，然后对该两个薄膜同时进行磁化。磁化后，参考图2的视图方向，第一磁体60、第二磁体61的上侧均为N极，下侧均为S极；反之亦可。
磁阻传感器70设置在衬底1上与第一磁体60、第二磁体61对应的位置。当膜板第一侧2受到外界的声压时，膜板第一侧2向衬底1的方向发生偏转，此时膜板第一侧2上的第一磁体60、第二磁体61靠近磁阻传感器70，从而使得磁阻传感器70可以感应第一磁体60、第二磁体61的共同磁场的变化，从而输出变化的电信号，实现了声电的转换。
磁阻传感器70可以设置在第一磁体60、第二磁体61中心线上。当第一磁体60、第二磁体61的上侧均为N极，下侧均为S极时，第一磁体60、第二磁体61的磁场方向均为由N极回到S极。因此在第一磁体60、第二磁体61中心线上的某个位置，第一磁体60、第二磁体61的磁场方向相反、磁场强度近似相同。该位置即为磁阻传感器70的初始位置。
由于磁阻传感器70同时受到两个磁体的作用，该两个磁体配合在一起，降低了整个磁场的强度，并在磁阻传感器70的线性范围内提高了磁场变化的灵敏度，最终提高了磁阻传感器70的检测灵敏度。
图4a示出了图2所示实施例中两个磁体与磁阻传感器分布的坐标图。在该坐标图中，原点位置位于两个磁体中心的位置。图4b、图4c示出了图2所示实施例中的磁场分布仿真图。两个磁体的尺寸均为6μm*4μm*0.5μm，两个磁体之间的间隙为2μm。图4b、图4c中的横坐标代表磁阻传感器相对于两个磁体中心位置的竖直距离z(m)，纵坐标代表磁场强度B(T)以及磁场变化梯度dB/dx(T/m)。图中的线a1代表B(T)随z(m)的变化曲线，线b1代表磁场变化梯度dB/dx(T/m)随z(m)的变化曲线。
磁阻传感器70初始位置的磁场强度为0，即线a1中B(T)为0的位置，此时z(m)约为4μm，即磁阻传感器70的初始位置为磁阻传感器70至两个磁体中心距离4μm的位置。在该初始位置时，线b1的值约为2.0*10 5T/m。即在该位置时磁场变化梯度为2.0*10 5T/m。相对于传统的单磁体结构而言，大大提高了磁场变化的灵敏度。另外线b1在该初始位置左右两侧的区域表现的较为平坦，这保证了磁阻传感器70可以处于其线性检测区域内。
在本发明一个优选的实施方式中，第一检测结构中的磁阻传感器可以设置有多个，例如图2示出的实施例，分别设置了两个磁阻传感器，每个磁阻传感器对应两个磁体。第一检测结构和第二检测结构的结构相同，且对称设置，使得两个检测结构可以构成惠斯通全桥电路，以保证麦克风可以输出表征声音变化信息的电信号。
对于本领域的技术人员而言，也可以将第一磁体60、第二磁体61设置在衬底1上，将磁阻传感器70设置在膜板第一侧2的相应位置上。当膜板偏转的时候，带动磁阻传感器70的位置发生变化，同样可以实现相同的效果，在此不再具体说明。需要注意的是，当磁阻传感器设置在膜板上时，为了避免引线对膜板的偏转带来影响，引线部可以经过弹性扭梁4的位置引出，在此不再具体说明。
双磁体实施例2
在本发明一个具体的实施方式中，膜板的上方还设置有承载部15，参考图5。承载部15可以通过间隔部直接或者间接连接在衬底1上，承载部15与膜板之间具有一定的间隙，使得承载部15不会阻碍膜板偏转。
参考图5，第一检测结构的第一磁体63、第二磁体62分别设置在衬底1上、承载部15上。第一磁体63、第二磁体62可以采用磁性薄膜，磁性薄膜可以直接采用磁性材质，也可以是形成薄膜后对该薄膜进行充磁。在本发明一个具体的实施方式中，磁性薄膜可以采用CoCrPt或者CoPt材质。为了保护磁体，第一磁体63、第二磁体62分别可以设置保护结构，例如通过绝缘层、钝化层进行覆盖等，在此不再具体说明。
第一磁体63、第二磁体62以磁极方向相反的方式分别布置在衬底1、承载部15上。参考图5的视图方向，当第一磁体63的左侧为N极、右侧为S极时，则第二磁体62的左侧为S极、右侧为N极；反之亦可。
参考图5的实施例，磁阻传感器71设置在膜板的第一侧2上与第一磁体63、第二磁体62相对应的位置，为了将磁阻传感器71的电信号引出，可以在膜板上设置引线部，该引线部一端与磁阻传感器71连接，另一端在膜板上延伸并通过弹性扭梁4的位置引出，在此不再具体说明。
当膜板的第一侧2受到外界的声压时，膜板的第一侧2向衬底1的方向发生偏转，此时膜板第一侧2上的磁阻传感器71靠近第一磁体63、远离第二磁体62，从而使得磁阻传感器71可以感应第一磁体63、第二磁体62的共同磁场的变化，输出变化的电信号，实现了声电的转换。
优选的是，第一磁体63、第二磁体62优选相对于磁阻传感器71对称，磁阻传感器71的该位置即为其初始位置。
当第一磁体63的左侧为N极，右侧为S极，而第二磁体62的左侧为S极，右侧为N极时，第一磁体63、第二磁体62的磁场方向均由N极回到S极。这种竖直的布置方式，使得在第一磁体63、第二磁体62中心的位置，第一磁体63、第二磁体62的磁场方向相反、磁场强度近似相同。
当磁阻传感器71随着膜板偏转时，磁阻传感器71会以该中心位置为初始位置进行上下振动。在该初始位置时，磁阻传感器71受到两个磁体的磁场大小一致，方向相反。例如当膜板第一侧2朝向承载部15的方向偏转时，磁阻传感器71靠近第二磁体62而远离第一磁体63，根据磁体的特点可以得知，磁阻传感器71受到第二磁体62的影响大于其受到第一磁体63的影响；反之亦然。
由于磁阻传感器71同时受到两个磁体的作用，该两个磁体配合在一起，降低了整个磁场的强度，并在磁阻传感器71的线性范围内提高了磁场变化的灵敏度，最终提高了磁阻传感器71的检测灵敏度。
图6a示出了图5所示实施例中两个磁体与磁阻传感器分布的坐标图。在该坐标图中，原点位置位于下磁体(第一磁体63)的中心位置。图6b示出了图5所示实施例中的磁场分布仿真图。两个磁体的尺寸均为2μm*1μm*0.1μm，两个磁体之间的距离为2μm。图6b中的横坐标代表磁阻传感器相对于下磁体中心位置的竖直距离z(m)，纵坐标代表磁场强度Bx(T)以及磁场变化梯度dB/dz(T/m)。图中的线a2代表Bx(T)随着z(m)的变化曲线，线b2代表磁场变化梯度dB/dz(T/m)随z(m)的变化曲线。
磁阻传感器71初始位置的磁场强度为0，即线a2中Bx(T)为0的位置，此时z(m)约为1μm(1.0E-06)，即磁阻传感器71的初始位置为 磁阻传感器71至下磁体(第一磁体63)中心距离1μm的位置。在该初始位置时，线b2的值约为1.6*10 6T/m。即在该位置时磁场变化梯度为1.6*10 6T/m。相对于传统的单磁体结构而言，大大提高了磁场变化的灵敏度。另外线b2在该初始位置左右两侧的区域表现的较为平坦，这保证了磁阻传感器71可以处于其线性检测区域内。
在本发明一个优选的实施方式中，第一检测结构中的磁阻传感器可以设置有多个，例如第一检测结构和第二检测结构中分别设置了两个磁阻传感器，每个磁阻传感器对应两个磁体。第一检测结构和第二检测结构的结构相同，且对称设置，使得两个检测结构可以构成惠斯通全桥电路，以保证麦克风可以输出表征声音变化信息的电信号。
无论是双磁体结构还是单磁体结构，都需要对膜板的初始位置进行校准。这是因为在制造、装配的时候，难免会因为误差对初始位置造成影响，因此需要设置一驱动装置来调节膜板的初始位置。
参考图2，该驱动装置例如可以为设置在弹性扭梁4位置的压电片16，该压电片16被配置为驱动弹性扭梁4变形。压电片16可以选用本领域技术人员所熟知的AlN、PZT或ZnO材质等。通过对压电片施加直流偏压，使得压电片16驱动弹性扭梁发生一定程度的变形，从而达到调整膜板初始位置的目的。
在本发明另一个实施方式中，驱动装置可以为用于给膜板提供偏转静电力的电极片。通过该电极片可以对振膜的第一侧或者第二侧施加静电力，以使膜板发生一定的偏转，同样实现了位置的调节。
本发明的麦克风在应用到装配结构中时，可以采用顶部安装(TOP型)的方式，也可以采用底部安装(Bottom型)结构，优选的是，封装结构的声孔可以与膜板的第一侧2正对或者靠近，使得声音可以直接作用在膜板的第一侧2上，在此不再具体说明。
虽然已经通过例子对本发明的一些特定实施例进行了详细说明，但是本领域的技术人员应该理解，以上例子仅是为了进行说明，而不是为了限制本发明的范围。本领域的技术人员应该理解，可在不脱离本发明的范围和精神的情况下，对以上实施例进行修改。本发明的范围由所附权利要求 来限定。

Claims (14)

  1. 一种麦克风，其特征在于：包括衬底、膜板，所述膜板的中部位置通过弹性扭梁连接在衬底上，所述膜板在衬底上形成了跷跷板结构；以弹性扭梁为界，所述膜板发生偏转运动的相对两侧分别记为第一侧、第二侧，其中在膜板第二侧的位置设置有多个供声音穿过的镂空；所述膜板被配置为受到声音信号时以弹性扭梁为轴发生偏转；
    在所述膜板的第一侧、第二侧还分别形成了用于表征膜板相应侧偏转电信号的第一检测结构、第二检测结构；所述第一检测结构和第二检测结构构成了差分结构；
    所述第一检测结构、第二检测结构分别包含磁体以及用于与磁体配合在一起的磁阻传感器。
  2. 根据权利要求1所述的麦克风，其特征在于：第一检测结构、第二检测结构中的磁阻传感器分别至少设置有一个，第一检测结构、第二检测结构中的磁阻传感器构成了惠斯通电桥。
  3. 根据权利要求1或2所述的麦克风，其特征在于：每个磁阻传感器对应一个磁体，所述磁体和磁阻传感器中的一个设置在膜板上，另一个设置在衬底上。
  4. 根据权利要求1至3任一项所述的麦克风，其特征在于：所述第一检测结构、第二检测结构的结构相同，每个磁阻传感器对应两个磁体，分别记为第一磁体、第二磁体，磁阻传感器设置在第一磁体、第二磁体形成的共同磁场中；初始位置时，所述磁阻传感器位于第一磁体的磁场方向与第二磁体的磁场方向相反的位置；所述磁阻传感器被配置为在膜板的偏转过程中感应第一磁体、第二磁体共同磁场的变化而输出变化的电信号。
  5. 根据权利要求1至4任一项所述的麦克风，其特征在于，初始位置时，所述磁阻传感器受到第一磁体的磁场，与受到第二磁体的磁场大小相等，方向相反。
  6. 根据权利要求1至5任一项所述的麦克风，其特征在于，所述第一磁体、第二磁体以磁极方向相同的方式依次水平布置在膜板上，所述磁阻 传感器设置在衬底上与第一磁体、第二磁体相对应的位置；
    或者，所述第一磁体、第二磁体以磁极方向相同的方式依次水平布置在衬底上，所述磁阻传感器设置在膜板上与第一磁体、第二磁体相对应的位置。
  7. 根据权利要求1至6任一项所述的麦克风，其特征在于，还设置有位于膜板上方的承载部，所述磁阻传感器设置在膜板上，所述第一磁体、第二磁体分别设置在位于振膜两侧的衬底、承载部上，且第一磁体、第二磁体的以磁极方向相反的方式进行布置。
  8. 根据权利要求1至7任一项所述的麦克风，其特征在于，所述第一磁体、第二磁体相对于磁阻传感器对称。
  9. 根据权利要求1至8任一项所述的麦克风，其特征在于，所述衬底上具有与膜板第一侧对应的第一中空腔，以及与膜板第二侧对应的第二中空腔。
  10. 根据权利要求1至9任一项所述的麦克风，其特征在于，在所述衬底远离膜板的一端还设置有将第一中空腔、第二中空腔封闭的基板。
  11. 根据权利要求1至10任一项所述的麦克风，其特征在于，所述第一中空腔、第二中空腔连通在一起。
  12. 根据权利要求1至11任一项所述的麦克风，其特征在于，还包括调节膜板初始位置的驱动装置。
  13. 根据权利要求1至12任一项所述的麦克风，其特征在于，所述驱动装置为设置在弹性扭梁位置的压电片，所述压电片被配置为驱动弹性扭梁变形。
  14. 根据权利要求1至13任一项所述的麦克风，其特征在于，所述驱动装置为用于给膜板提供偏转静电力的电极片。
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