Electromagnetic microphone

Abstract

An electromagnetic microphone, comprising a circuit board, a housing which is in covered connection with the circuit board so as to enclose an accommodating space, and a sound sensor, wherein a sound hole in communication with the accommodating space penetrates one of the circuit board and the housing, and the sound sensor comprises: a substrate, which is provided in the accommodating space and is fixed to the circuit board, the substrate being provided with a cavity; a vibration member, which is fixedly arranged on the side of the substrate away from the circuit board and covers the cavity, external sound waves acting on the vibration member via the sound hole, the vibration member comprising a diaphragm fixed to the substrate and a magnetic element having a magnetic field, and the magnetic element being fixed to the diaphragm; and a coil, and when the vibration member vibrates, the coil cuts the magnetic field of the magnetic element to generate an electrical signal. Compared with a traditional capacitive microphone, the electromagnetic microphone of the present invention does not have a back plate structure, such that not only can damping and noise be greatly reduced, but the problem of damage to a membrane due to same being suctioned can also be avoided, thereby improving the reliability of the electromagnetic microphone.

Description

electromagnetic microphone Technical Field

[0001] The present invention relates to the field of acoustics and electricity, and in particular to an electromagnetic microphone. Background Art

[0002] Microphones, fundamental components of voice communication, have evolved over the years and are now used in a wide range of fields. All microphones (both traditional and MEMS) sense sound waves through a flexible diaphragm, which displaces under the pressure of the sound waves.

[0003] Currently, most microphones on the market use capacitive technology to detect sound. Capacitive MEMS microphones work by measuring the capacitance between a flexible diaphragm and a fixed backplate. The air pressure changes caused by sound waves cause the diaphragm to shift, allowing air to pass through the small holes in the backplate, thus maintaining its position. As the diaphragm moves, the distance between the diaphragm and the backplate changes, ultimately causing a change in the capacitance between them, thereby achieving sound-to-electricity conversion. However, capacitive MEMS microphones suffer from high impedance, high noise, and backplate absorption, which significantly reduce the microphone's reliability.

[0004] Therefore, it is necessary to study a new microphone. Summary of the Invention

[0005] The present invention aims to solve the problems of high impedance, high noise and film absorption of the back plate of the microphone, and provides a novel electromagnetic microphone with a back plate-free structure.

[0006] To achieve the above-mentioned objectives, the present invention provides an electromagnetic microphone, which includes a circuit board, a shell connected to the circuit board cover to enclose a receiving space, and an acoustic sensor, wherein a sound hole communicating with the receiving space is provided on one of the circuit board and the shell, and the acoustic sensor includes: a base, which is arranged in the receiving space and fixed to the circuit board, and the base has a cavity; a vibrating member, which is fixed to a side of the base away from the circuit board and covers the cavity, and external sound waves act on the vibrating member through the sound hole, and the vibrating member includes a diaphragm fixed to the base and a magnetic element with a magnetic field, and the magnetic element is fixed on the diaphragm; and a coil; wherein, when the vibrating member vibrates, the coil cuts the magnetic field of the magnetic element to generate an electrical signal.

[0007] As an improvement, the magnetic element is a magnetic film.

[0008] As an improvement, the magnetic element has an anisotropic magnetic field.

[0009] As an improvement, the orthographic projection of the magnetic element on the substrate is located within the range of the cavity.

[0010] As an improvement, the circuit board has an outer surface and an inner surface arranged opposite to each other, the base is fixed to the inner surface, and the coil includes a coil portion and a first lead portion and a second lead portion extending from the coil portion, wherein the coil portion cuts the magnetic field of the magnetic element.

[0011] As an improvement, the coil is integrated into the circuit board.

[0012] As an improvement, the first lead portion and the second lead portion both extend to the outer surface, and the first lead portion and the second lead portion are both electrically connected to an external circuit on the outer surface.

[0013] As an improvement, the first lead portion forms a first pad electrically connected to an external circuit on the outer surface, and the second lead portion forms a second pad electrically connected to an external circuit on the outer surface.

[0014] As an improvement, the electromagnetic microphone further includes an integrated circuit chip fixed to the inner surface, the first lead portion and the second lead portion both extend to the inner surface, and the first lead portion and the second lead portion are electrically connected to the integrated circuit chip on the inner surface.

[0015] As an improvement, the coil portion includes a plurality of layers of planar coils arranged in sequence along the vibration direction of the vibrating member and an electrical connection portion connecting two adjacent layers of the planar coils in series, and the circuit board includes a connection hole provided between two adjacent planar coils, and the connection hole is filled with the electrical connection portion, wherein the plurality of layers of planar coils include a first planar coil leading out the first lead portion and a second planar coil leading out the second lead portion.

[0016] As an improvement, the coil is integrated into the substrate.

[0017] As an improvement, the first lead portion and the second lead portion both extend to the side of the base facing away from the diaphragm, and the circuit board is integrated with a connecting circuit extending from the inner surface to the outer surface. The connecting circuit is electrically connected to the external circuit on the outer surface, and the connecting circuit is also electrically connected to the first lead portion and the second lead portion on the inner surface.

[0018] As an improvement, the connection circuit forms a third pad and a fourth pad on the outer surface that are electrically connected to an external circuit.

[0019] As an improvement, the first lead portion and the second lead portion both extend to the side of the base away from the diaphragm, the electromagnetic microphone also includes an integrated circuit chip fixed to the inner surface, and a connecting circuit is integrated in the circuit board, one end of the connecting circuit is electrically connected to the first lead portion and the second lead portion on the inner surface, and the other end thereof is electrically connected to the integrated circuit chip on the inner surface.

[0020] As an improvement, the base includes a first insulating layer fixed on the diaphragm, a second insulating layer fixed on the inner surface, and an intermediate insulating layer, the second insulating layer is penetrated by a first hole and a second hole filled by the second lead portion, the intermediate insulating layer is penetrated by a via and a third hole connected to the first hole, the first lead portion includes a first conductive portion filling the first hole and a second conductive portion filling the third hole, the coil portion is arranged between the first insulating layer and the second insulating layer, the coil portion includes multiple layers of planar coils arranged at intervals and an electrical connection portion connecting two adjacent layers of the planar coils in series, an intermediate insulating layer is provided between the two adjacent layers of the planar coils, and the via is filled by the electrical connection portion.

[0021] As an improvement, the forming method of the coil integrated in the substrate includes the following steps: step 1, depositing on the first insulating layer to form a planar coil; step 2, depositing on the planar coil to form an intermediate insulating layer blank; step 3, etching on the intermediate insulating layer blank to form a via hole and a third hole to form an intermediate insulating layer; step 4, depositing in the via hole to form an electrical connection portion; step 5, depositing in the third hole to form a second conductive portion; step 6, depositing on the intermediate insulating layer to form a planar coil; step 7, repeating steps 2 to 6 in sequence; step 8, depositing on the planar coil to form a second insulating layer blank; step 9, etching on the second insulating layer blank to form a first hole and a second hole to form a second insulating layer; step 10, depositing in the first hole to form a first conductive portion; step 11, depositing in the second hole to form a second lead portion.

[0022] As an improvement, the integrated circuit chip includes a signal processing module electrically connected to the coil and a signal detection module electrically connected to the signal processing module, wherein the electrical signal is processed by the signal processing module and then received and output by the signal detection module to obtain information about the external sound wave signal.

[0023] As an improvement, the signal detection module also outputs a control signal to the coil based on the received electrical signal so that the coil generates an electromagnetic force acting in the opposite direction to the magnetic element, and the electromagnetic force and the force of the external sound wave on the vibrating member cancel each other out.

[0024] As an improvement, the signal processing module includes a signal amplifying unit electrically connected to the coil, an analog-to-digital conversion unit electrically connected to the signal amplifying unit, and a filtering unit connecting the analog-to-digital conversion unit and the signal detection module.

[0025] The present invention has the following beneficial effects: an acoustic sensor comprises a base having a cavity, a vibrating element, and a coil. The base is disposed within a receiving space and fixed to a circuit board. The vibrating element comprises a diaphragm and a magnetic element having a magnetic field. The diaphragm is fixed to the side of the base facing away from the circuit board and covers the cavity. The magnetic element is fixed to the diaphragm. When an external sound wave acts on the vibrating element, the magnetic element and the diaphragm produce the same displacement and vibration, causing the relative distance between the magnetic element and the coil to change. At this time, the coil cuts the magnetic field formed by the magnetic element. According to the law of electromagnetic induction, a current is generated in the coil and a voltage is generated across it (i.e., the coil cuts the magnetic field formed by the magnetic element, generating an electrical signal), thereby achieving sound-to-electricity conversion. The external sound wave signal can be obtained by detecting the current and voltage generated by the coil. Compared to traditional condenser microphones, the electromagnetic microphone of the present invention has no backplate structure, which not only greatly reduces damping and noise but also avoids the problem of diaphragm damage, thereby improving the reliability of the electromagnetic microphone. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] FIG1 is a schematic structural diagram of an electromagnetic microphone according to a first embodiment of the present invention.

[0027] FIG. 2 is a schematic diagram of a partial structure of a circuit board integrated with a coil in the electromagnetic microphone shown in FIG. 1 .

[0028] FIG3 is a schematic structural diagram of a coil in the circuit board integrated with the coil shown in FIG2 .

[0029] FIG4 is a schematic diagram of a top view of the planar coil in the coil shown in FIG3 .

[0030] FIG5 is a partially cutaway perspective view of the acoustic sensor and circuit board in the electromagnetic microphone shown in FIG1 .

[0031] FIG6 is an enlarged view of part a of the acoustic sensor and circuit board shown in FIG5 .

[0032] FIG. 7 is a perspective view of the circuit board integrated with the coil shown in FIG. 5 .

[0033] FIG8 is a schematic structural diagram of an electromagnetic microphone according to a second embodiment of the present invention.

[0034] FIG9 is a schematic structural diagram of the integrated circuit chip in the electromagnetic microphone shown in FIG8 or FIG22.

[0035] FIG10 is a control principle diagram of the electromagnetic microphone shown in FIG8 or FIG22.

[0036] FIG11 is a schematic structural diagram of an electromagnetic microphone according to a third embodiment of the present invention.

[0037] FIG12 is a three-dimensional diagram of a partially cut-away acoustic sensor in the electromagnetic microphone shown in FIG11 .

[0038] FIG13 is a schematic diagram of a partial structure in which a first insulating layer is deposited on the diaphragm.

[0039] FIG14 is a schematic diagram of a partial structure of a planar coil formed by deposition on a first insulating layer.

[0040] FIG15 is a schematic diagram of a partial structure of a rough intermediate insulating layer formed by deposition on a planar coil.

[0041] FIG16 is a schematic diagram of a partial structure of etching a via hole and a third hole on the intermediate insulating layer blank to form an intermediate insulating layer.

[0042] FIG17 is a partial structural diagram showing that an electrical connection portion is formed by deposition in a via hole, a second conductive portion is formed by deposition in a third hole, and a planar coil is formed by deposition on an intermediate insulating layer.

[0043] FIG18 is a partial structural diagram showing that an intermediate insulating layer, a planar coil, an intermediate insulating layer and a planar coil are sequentially formed on the planar coil on the intermediate insulating layer.

[0044] FIG19 is a schematic diagram of a partial structure of a rough blank of a second insulating layer deposited on a planar coil.

[0045] FIG20 is a schematic diagram of a partial structure of etching a first hole and a second hole on a second insulating layer rough blank to form a second insulating layer.

[0046] FIG21 is a schematic diagram of a partial structure in which a first conductive portion is formed by deposition in a first hole and a second lead portion is formed by deposition in a second hole.

[0047] FIG22 is a schematic structural diagram of an electromagnetic microphone according to a fourth embodiment of the present invention. DETAILED DESCRIPTION

[0048] The present invention will be described in detail below with reference to Figures 1 to 22. Figures 13 to 21 are schematic structural diagrams of the electromagnetic microphone shown in Figure 11 during the molding process in which the coil is integrated into the substrate.

[0049] 1 to 7 , the electromagnetic microphone according to the first embodiment of the present invention includes a circuit board 1 , a housing 3 covering the circuit board 1 to form a receiving space A, and an acoustic sensor 5 .

[0050] A sound hole B is formed through one of the circuit board 1 and the housing 3 and is connected to the receiving space A. External sound waves act on the sound sensor 5 through the sound hole B, and the sound sensor 5 converts the external sound waves into electrical signals.

[0051] As shown in FIG. 1 , in this embodiment, a sound hole B communicating with the receiving space A is formed through the circuit board 1 .

[0052] The circuit board 1 has an outer surface 11 and an inner surface 13 disposed opposite to each other.

[0053] The inner surface 13 faces the receiving space A.

[0054] In this embodiment, the housing 3 is a metal shell with electromagnetic shielding function.

[0055] The acoustic sensor 5 includes a substrate 51 , a vibrating element 53 and a coil 55 .

[0056] The base 51 is disposed in the receiving space A and fixed to the circuit board 1 . Specifically, the base 51 is fixed to the inner surface 13 of the circuit board 1 .

[0057] The substrate 51 has a cavity 51A.

[0058] The cavity 51A communicates with the acoustic hole B on the circuit board 1 .

[0059] The vibrating member 53 is fixed to a side of the base 51 facing away from the circuit board 1 and covers the cavity 51A.

[0060] External sound waves act on the vibrating member 53 through the sound hole B to drive the vibrating member 53 to vibrate.

[0061] The vibrating member 53 includes a diaphragm 531 fixed to the base 51 and a magnetic element 533 having a magnetic field.

[0062] The magnetic element 533 is fixed on the diaphragm 531 .

[0063] As shown in FIG. 1 and FIG. 5 , in this embodiment, the diaphragm 531 covers the cavity 51A, and the magnetic element 533 is fixed on a side of the diaphragm 531 facing the circuit board 1 .

[0064] It is understandable that in other embodiments, the magnetic element may also be fixed on the side of the diaphragm facing away from the circuit board 1; or, magnetic elements may be fixed on both opposite sides of the diaphragm along the vibration direction of the vibrating member.

[0065] In this embodiment, the orthographic projection of the magnetic element 533 on the substrate 51 is located within the cavity 51A, thereby preventing the magnetic element 533 from providing a certain supporting force to the diaphragm 531, which would reduce the vibration amplitude of the vibrating element 53 and reduce the sensitivity of the electromagnetic microphone.

[0066] It should be noted that when the orthographic projection of the magnetic element 533 on the substrate 51 is within the range of the cavity 51A, the magnetic element and the diaphragm can be located in the same plane. For example, the diaphragm is designed as a ring-shaped structure arranged around the magnetic element, and its inner periphery is connected to the magnetic element so that the magnetic element and the diaphragm cooperate to cover the cavity 51A.

[0067] In this embodiment, the magnetic element 533 is a magnetic film, wherein the material of the magnetic film can be iron / platinum hard magnetic material or other magnetic materials.

[0068] In this embodiment, the magnetic film is directly formed on the diaphragm 531 by a magnetic material deposition or sputtering process, thereby improving the connection strength between the magnetic element 533 and the diaphragm 531.

[0069] In this embodiment, the magnetic element 533 has an anisotropic magnetic field.

[0070] The coil 55 is integrated into the circuit board 1 .

[0071] When external sound waves act on the vibrating member 53 through the sound hole B to drive the vibrating member 53 to vibrate, the magnetic element 533 and the diaphragm 531 produce the same displacement and vibration, thereby causing the relative distance between the magnetic element 533 and the coil 55 to change. At this time, the coil 55 cuts the magnetic field formed by the magnetic element 533. According to the law of electromagnetic induction, a current is generated in the coil 55 and a voltage is generated at both ends of it (that is, the coil 55 cuts the magnetic field formed by the magnetic element 533 to generate an electrical signal), thereby realizing sound-to-electricity conversion. By detecting the current and voltage generated by the coil 55, the external sound wave signal can be obtained.

[0072] The coil 55 includes a coil portion 57 and a first lead portion 58 and a second lead portion 59 extending from the coil portion 57 , wherein the coil portion 57 cuts the magnetic field of the magnetic element 533 .

[0073] In this embodiment, the coil portion 57 includes a plurality of layers of planar coils 571 arranged in sequence along the vibration direction of the vibrating member 53 and an electrical connection portion 573 connecting two adjacent layers of planar coils 571 in series. The circuit board 1 includes a connection hole 15 arranged between the two adjacent planar coils 571, and the connection hole 15 is filled with the electrical connection portion 573.

[0074] The multilayer planar coil 571 includes a first planar coil 575 extending from a first lead portion 58 and a second planar coil 576 extending from a second lead portion 59. In other words, the coil 55 can be equivalent to a wire wound into a coil.

[0075] As shown in Figures 3 to 7, the planar coil 571 is square, and accordingly, the coil portion 57 is also square. It is understood that the planar coil 571 can have various shapes. In other embodiments, the planar coil 571 can also be circular or other shapes.

[0076] The first lead portion 58 and the second lead portion 59 both extend to the outer surface 11 and are electrically connected to an external circuit at the outer surface 11. The current and voltage generated by the coil 55 are detected by the external circuit.

[0077] As shown in Figure 1, in order to facilitate the electrical connection of the first lead portion 58 and the second lead portion 59 to the external circuit, in this embodiment, the first lead portion 58 forms a first solder pad 581 electrically connected to the external circuit on the outer surface 11, and the second lead portion 59 forms a second solder pad 591 electrically connected to the external circuit on the outer surface 11.

[0078] It should be noted that, in this embodiment, the circuit board 1 integrated with the coil portion 57 is a multi-layer circuit board, and each layer of the planar coil 571 is a conductive layer of the multi-layer circuit board.

[0079] It can be understood that in other embodiments, the circuit board 1 can also be a single-sided board or a double-sided board (that is, the coil portion 57 has only one or two layers of planar coils). Compared with a multi-layer circuit board, the electrical signal strength generated by the coil of the single-sided board or the double-sided board cutting the magnetic field formed by the magnetic element is relatively low.

[0080] Please refer to FIG. 8 to FIG. 10 . The electromagnetic microphone according to the second embodiment of the present invention differs from the electromagnetic microphone according to the first embodiment only in that the electromagnetic microphone further includes an integrated circuit chip 7 fixed to the inner surface 13 .

[0081] The first lead portion 58 and the second lead portion 59 both extend to the inner surface 13 , and the first lead portion 58 and the second lead portion 59 are electrically connected to the integrated circuit chip 7 on the inner surface 13 .

[0082] The integrated circuit chip 7 includes a signal processing module 71 electrically connected to the coil 55 and a signal detection module 73 electrically connected to the signal processing module 71 .

[0083] When external sound waves act on the vibrating member 53 through the sound hole B to drive the vibrating member 53 to vibrate (that is, sound pressure acts on the vibrating member 53 to drive the vibrating member 53 to vibrate), the magnetic element 533 and the diaphragm 531 produce the same displacement and vibration, thereby causing the relative distance between the magnetic element 533 and the coil 55 to change. At this time, the coil 55 cuts the magnetic field formed by the magnetic element 533. According to the law of electromagnetic induction, current is generated in the coil 55 and voltage is generated at both ends of it (that is, the coil 55 cuts the magnetic field formed by the magnetic element 533 to generate an electrical signal), thereby realizing sound-to-electricity conversion. The electrical signal generated by the coil 55 cutting the magnetic field is processed by the signal processing module 71 and then received and output by the signal detection module 73 to obtain information about the external sound wave signal.

[0084] The signal processing module 71 includes a signal amplifying unit 711 electrically connected to the coil 55 , an analog-to-digital conversion unit 713 electrically connected to the signal amplifying unit 711 , and a filtering unit 715 connecting the analog-to-digital conversion unit 713 and the signal detecting module 73 .

[0085] In this embodiment, the signal detection module 73 also outputs a control signal to the coil 55 based on the received electrical signal, causing the coil 55 to generate an electromagnetic force that acts in opposition to the electromagnetic force of the magnetic element 533. The electromagnetic force and the force exerted by the external sound waves on the vibrating element 53 cancel each other out. This not only creates a closed-loop electromagnetic microphone, thereby reducing the stiffness of the diaphragm 531 for high sensitivity, but also resolves the conflict between sensitivity and bandwidth in open-loop microphones. Furthermore, during operation or in the event of a drop or collision, the diaphragm 531 can be controlled through closed-loop force feedback to maintain its original position, effectively improving the stability and reliability of the electromagnetic microphone.

[0086] 11 to 21 , the electromagnetic microphone according to the third embodiment of the present invention differs from the electromagnetic microphone according to the first embodiment only in that the coil 55 is integrated into the substrate 51 , and the first lead portion 58 and the second lead portion 59 of the coil 55 both extend to the side of the substrate 51 away from the diaphragm 531 .

[0087] Specifically, the substrate 51 includes a first insulating layer 511 fixed on the diaphragm 531 , a second insulating layer 513 fixed on the inner surface 13 , and an intermediate insulating layer 515 .

[0088] In this embodiment, the first insulating layer 511 , the second insulating layer 513 and the intermediate insulating layer 515 are all insulating layers made of silicon dioxide material.

[0089] The second insulating layer 513 is penetrated by a first hole 51A and a second hole 51B filled with the second lead portion 59 .

[0090] The intermediate insulating layer 515 is penetrated by a via hole 51C and a third hole 51D communicating with the first hole 51A.

[0091] The first lead portion 58 includes a first conductive portion 583 filling the first hole 51A and a second conductive portion 585 filling the third hole 51D.

[0092] The coil portion 57 is provided between the first insulating layer 511 and the second insulating layer 513 .

[0093] The coil portion 57 includes multiple layers of planar coils 571 spaced apart and an electrical connection portion 573 connecting two adjacent layers of planar coils 571 in series. An intermediate insulating layer 515 is provided between the two adjacent layers of planar coils 571 , and the via 51C is filled with the electrical connection portion 573 .

[0094] Referring to Figures 13 to 21, the method for forming the coil 55 integrated into the substrate 51 includes the following steps: Step 1, depositing a planar coil 571 on the first insulating layer 511; Step 2, depositing a middle insulating layer blank 55A on the planar coil 571; Step 3, etching a via hole 51C and a third hole 51D on the middle insulating layer blank 55A to form the middle insulating layer 515; Step 4, depositing an electrical connection portion 573 in the via hole 51C; Step 5, depositing a third hole 51D in the third hole 51D. Second conductive part 585; Step six, depositing on the middle insulating layer 515 to form a planar coil 571; Step seven, repeating steps two to six in sequence; Step eight, depositing on the planar coil 571 to form a second insulating layer rough blank 55B; Step nine, etching on the second insulating layer rough blank 55B to form a first hole 51A and a second hole 51B to form a second insulating layer 513; Step ten, depositing in the first hole 51A to form a first conductive part 583; Step eleven, depositing in the second hole 51B to form a second lead part 59.

[0095] In this embodiment, the first insulating layer 511 is deposited and formed on the diaphragm 531 .

[0096] It should be noted that the above steps 4, 5 and 6 can be performed simultaneously, or the above steps 4 and 5 can be performed first and then step 6; the above steps 10 and 11 can be performed simultaneously.

[0097] The circuit board 1 is a single-layer circuit board.

[0098] The circuit board 1 integrates a connection circuit 17 extending from the inner surface 13 to the outer surface 11 .

[0099] The connection circuit 17 is electrically connected to an external circuit on the outer surface 11 .

[0100] The connection circuit 17 is also electrically connected to the first lead portion 58 and the second lead portion 59 on the inner surface 13 .

[0101] In order to facilitate electrical connection between the connection circuit 17 and an external circuit, in this embodiment, the connection circuit 17 forms a third pad 171 and a fourth pad 173 on the outer surface 11 for electrical connection with the external circuit.

[0102] 9 , 10 and 22 , the electromagnetic microphone according to the fourth embodiment of the present invention differs from the electromagnetic microphone according to the third embodiment only in that the electromagnetic microphone further includes an integrated circuit chip 7 fixed to the inner surface 13 .

[0103] One end of the connection circuit 17 is electrically connected to the first lead portion 58 and the second lead portion 59 on the inner surface 13 , and the other end thereof is electrically connected to the integrated circuit chip 7 on the inner surface 13 .

[0104] Integrated circuit chip 7 includes a signal processing module 71 electrically connected to coil 55 and a signal detection module 73 electrically connected to signal processing module 71. The electrical signal generated by coil 55 cutting the magnetic field is processed by signal processing module 71 and then received and output by signal detection module 73 to obtain information about the external sound wave signal.

[0105] The signal processing module 71 includes a signal amplifying unit 711 electrically connected to the coil 55 , an analog-to-digital conversion unit 713 electrically connected to the signal amplifying unit 711 , and a filtering unit 715 connecting the analog-to-digital conversion unit 713 and the signal detecting module 73 .

[0106] In this embodiment, the signal detection module 73 also outputs a control signal to the coil 55 based on the received electrical signal, causing the coil 55 to generate an electromagnetic force that acts in opposition to the electromagnetic force of the magnetic element 533. The electromagnetic force and the force exerted by the external sound waves on the vibrating element 53 cancel each other out. This not only creates a closed-loop electromagnetic microphone, thereby reducing the stiffness of the diaphragm 531 for high sensitivity, but also resolves the conflict between sensitivity and bandwidth in open-loop microphones. Furthermore, during operation or in the event of a drop or collision, the diaphragm 531 can be controlled through closed-loop force feedback to maintain its original position, effectively improving the stability and reliability of the electromagnetic microphone.

[0107] The above description is only an embodiment of the present invention. It should be pointed out that those skilled in the art can make improvements without departing from the creative concept of the present invention, but these improvements all fall within the scope of protection of the present invention.

Claims

1. An electromagnetic microphone, comprising a circuit board, a housing that is covered and connected to the circuit board to enclose a receiving space, and a sound sensor, wherein one of the circuit board and the housing is provided with a sound hole penetrating therethrough and communicating with the receiving space, and is characterized in that, The acoustic sensor comprises: a substrate, which is arranged in the receiving space and fixed to the circuit board, and the substrate has a cavity; a vibrating member, which is fixed to a side of the substrate away from the circuit board and covers the cavity, and external sound waves act on the vibrating member through the sound hole, and the vibrating member comprises a diaphragm fixed to the substrate and a magnetic element with a magnetic field, and the magnetic element is fixed to the diaphragm; and a coil; wherein, when the vibrating member vibrates, the coil cuts the magnetic field of the magnetic element to generate an electrical signal.

2. The electromagnetic microphone according to claim 1, characterized in that, The magnetic element is a magnetic film.

3. The electromagnetic microphone according to claim 2, wherein The magnetic element has an anisotropic magnetic field.

4. The electromagnetic microphone according to any one of claims 1-3, characterized in that, The orthographic projection of the magnetic element on the substrate is located within the range of the cavity.

5. The electromagnetic microphone according to claim 1, characterized in that, The circuit board has an outer surface and an inner surface arranged opposite to each other, the base is fixed to the inner surface, and the coil includes a coil portion and a first lead portion and a second lead portion extending from the coil portion, wherein the coil portion cuts the magnetic field of the magnetic element.

6. The electromagnetic microphone according to claim 5, characterized in that, The coil is integrated in the circuit board.

7. The electromagnetic microphone according to claim 6, wherein The first lead portion and the second lead portion both extend to the outer surface, and the first lead portion and the second lead portion are both electrically connected to an external circuit on the outer surface.

8. The electromagnetic microphone according to claim 7, wherein The first lead portion forms a first pad on the outer surface electrically connected to an external circuit, and the second lead portion forms a second pad on the outer surface electrically connected to an external circuit.

9. The electromagnetic microphone according to claim 6, characterized in that, The electromagnetic microphone further includes an integrated circuit chip fixed to the inner surface, the first lead portion and the second lead portion both extend to the inner surface, and the first lead portion and the second lead portion are electrically connected to the integrated circuit chip on the inner surface.

10. The electromagnetic microphone according to any one of claims 6-9, characterized in that, The coil part includes a plurality of layers of planar coils arranged in sequence along the vibration direction of the vibrator and an electrical connection part connecting two adjacent layers of the planar coils in series, the circuit board includes a connection hole arranged between two adjacent planar coils, and the connection hole is filled with the electrical connection part, wherein the plurality of layers of planar coils include a first planar coil leading out the first lead part and a second planar coil leading out the second lead part.

11. The electromagnetic microphone according to claim 5, characterized in that, The coil is integrated into the substrate.

12. The electromagnetic microphone according to claim 11, wherein, The first lead portion and the second lead portion both extend to a side of the base facing away from the diaphragm, and the circuit board integrates a connecting circuit extending from the inner surface to the outer surface, the connecting circuit is electrically connected to an external circuit on the outer surface, and the connecting circuit is also electrically connected to the first lead portion and the second lead portion on the inner surface.

13. The electromagnetic microphone according to claim 12, characterized in that, The connection circuit forms a third pad and a fourth pad on the outer surface that are electrically connected to an external circuit.

14. The electromagnetic microphone according to claim 11, characterized in that, The first lead portion and the second lead portion both extend to a side of the substrate away from the diaphragm, the electromagnetic microphone also includes an integrated circuit chip fixed to the inner surface, a connecting circuit is integrated in the circuit board, one end of the connecting circuit is electrically connected to the first lead portion and the second lead portion on the inner surface, and the other end of the connecting circuit is electrically connected to the integrated circuit chip on the inner surface.

15. The electromagnetic microphone according to any one of claims 11 - 14, characterized in that, The substrate includes a first insulating layer fixedly provided on the diaphragm, a second insulating layer fixedly provided on the inner surface, and an intermediate insulating layer. A first hole is formed through the second insulating layer, and a second hole filled with the second lead portion is provided. A via hole is formed through the intermediate insulating layer, and a third hole communicating with the first hole is provided. The first lead portion includes a first conductive portion filling the first hole and a second conductive portion filling the third hole. The coil portion is disposed between the first insulating layer and the second insulating layer. The coil portion includes a plurality of planar coils arranged at intervals and an electrical connection portion connecting adjacent two layers of the planar coils in series. An intermediate insulating layer is provided between adjacent two layers of the planar coils, and the via hole is filled with the electrical connection portion.

16. The electromagnetic microphone according to claim 15, characterized in that, The forming method of integrating the coil into the substrate includes the following steps: Step 1, depositing and forming a planar coil on the first insulating layer; Step 2, depositing and forming a rough intermediate insulating layer on the planar coil; Step 3, etching the rough intermediate insulating layer to form a via hole and a third hole to form the intermediate insulating layer; Step 4, depositing and forming an electrical connection portion in the via hole; Step 5, depositing and forming a second conductive portion in the third hole; Step 6, depositing and forming a planar coil on the intermediate insulating layer; Step 7, sequentially repeating Steps 2 to 6; Step 8, depositing and forming a rough second insulating layer on the planar coil; Step 9, etching the rough second insulating layer to form a first hole and a second hole to form the second insulating layer; Step 10, depositing and forming a first conductive portion in the first hole; Step 11, depositing and forming a second lead portion in the second hole.

17. The electromagnetic microphone according to claim 9 or 14, characterized in that, The integrated circuit chip includes a signal processing module electrically connected to the coil and a signal detection module electrically connected to the signal processing module. Among them, the electrical signal is processed by the signal processing module and then received and output by the signal detection module to obtain information on an external sound wave signal.

18. The electromagnetic microphone according to claim 17, wherein, The signal detection module also outputs a control signal to the coil according to the received electrical signal so that the coil generates a reverse acting force on the electromagnetic force of the magnetic element, and the electromagnetic force and the acting force of the external sound wave on the vibrating member cancel each other out.

19. The electromagnetic microphone according to claim 17, wherein, The signal processing module includes a signal amplification unit electrically connected to the coil, an analog-to-digital conversion unit electrically connected to the signal amplification unit, and a filtering unit connecting the analog-to-digital conversion unit and the signal detection module.

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