Microphone device

Abstract

This invention provides a microphone device that can be mounted on equipment with noise sources, such as drones, and which can acquire ambient sound with noise generated by the equipment removed through a modular structure. [Solution] The microphone device comprises a microphone housing case 21 that encloses the microphone 21 and an acceleration sensor holding member 33 that holds the acceleration sensor 31. The microphone housing case 21 is made of a soft material that is softer and more elastic than the material that constitutes the microphone mounting section 2a of the drone 1, and the acceleration sensor holding member 33 is made of a hard material that is harder than the material that constitutes the acceleration sensor mounting section 2c of the drone 1. This allows the microphone 21 and the acceleration sensor 31 to be in close proximity, and enables the modularization of the microphone device 10.

Description

Technical Field

[0001] The present invention relates to a microphone device.

Background Art

[0002] When a device equipped with a microphone for acquiring ambient sound has a noise source such as a motor, the noise from the noise source may be mixed into the microphone as vibration noise (structure-borne sound) transmitted through the device itself and airborne noise (airborne sound) transmitted in the air. As a countermeasure, an acceleration sensor for acquiring vibration noise from the noise source is provided, and based on the vibration noise acquired by the acceleration sensor, removal noise having a correlation with the noise mixed into the microphone is generated, and a microphone device that removes the noise included in the ambient sound acquired by the microphone with the removal noise is known (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In a conventional microphone device, the acceleration sensor is arranged near the noise source, and a plastic partition plate and rubber for holding the microphone are arranged between the device and the microphone so that vibration noise from the noise source does not mix into the microphone, and the correlation between the vibration noise from the noise source acquired by the acceleration sensor and the noise mixed into the microphone, that is, the airborne noise from the noise source, is ensured. Therefore, there is a problem that the microphone and the acceleration sensor cannot be made into a structure close to each other, and the modularization of the microphone device cannot be achieved.

[0005] An object of the present invention is to provide a microphone device capable of acquiring ambient sound from which noise generated by a device has been removed in a modular structure. [Means for solving the problem]

[0006] The microphone device according to the present invention is a microphone device mounted on equipment having a noise source, comprising a microphone unit and an acceleration sensor unit, wherein the microphone unit comprises a microphone that acquires ambient sound of the equipment, a microphone housing case that constitutes the outer casing of the microphone unit and encloses the microphone, and a sound introduction hole drilled in the microphone housing case, wherein the microphone housing case is made of a soft material that is softer and more elastic than the material that constitutes the microphone mounting part of the equipment and is fixed to the microphone mounting part, wherein the acceleration sensor unit comprises an acceleration sensor that acquires vibration noise from the noise source transmitted through the equipment itself, an acceleration sensor substrate on which the acceleration sensor is mounted, and an acceleration sensor holding member that holds the acceleration sensor substrate, wherein the acceleration sensor substrate is made of a rigid substrate that does not have flexibility, and the acceleration sensor holding member is made of a hard material that is harder than the material that constitutes the acceleration sensor mounting part of the equipment and is fixed to the acceleration sensor mounting part.

[0007] According to the microphone device of the present invention, the microphone is enclosed in a microphone housing case made of a soft material that is softer and more elastic than the material constituting the microphone mounting section of the device, thereby eliminating vibration noise from noise sources that may enter the microphone. Furthermore, since the acceleration sensor is held in an acceleration sensor holding member made of a hard material that is harder than the material constituting the acceleration sensor mounting section of the device, vibration noise from noise sources that correlates with airborne noise transmitted from the noise source and enters the microphone can be acquired with high sensitivity, even without being placed near the noise source. As a result, the microphone and acceleration sensor can be placed in close proximity, enabling the modularization of the microphone device. [Effects of the Invention]

[0008] According to the present invention, a microphone device can be provided that can acquire ambient sound with noise generated by equipment removed by a modular structure. [Brief explanation of the drawing]

[0009] [Figure 1] This is an external view showing a device equipped with a microphone device according to an embodiment of the present invention. [Figure 2] This is a cross-sectional view showing the configuration of a microphone device according to an embodiment of the present invention. [Figure 3] This is a block diagram showing the configuration of the sound signal processing unit of a microphone device according to an embodiment of the present invention. [Modes for carrying out the invention]

[0010] Hereinafter, a microphone device 10 according to an embodiment of the present invention will be described with reference to the drawings.

[0011] Figure 1 shows an external view of a drone 1 as an example of a device on which a microphone device 10 is mounted. The drone (quadrotor) 1 comprises a body 2 (an example of the device itself), four arms 3 protruding in four directions from the body 2, four motors 4 attached to the ends of each arm 3 (an example of multiple noise sources), four propellers 5 attached to the rotation axis of each motor 4, a camera 6 mounted on the body 2, a battery (not shown), a flight control circuit, various sensors, a wireless communication circuit, etc., built into the body 2, and a microphone device 10 is also built into the body 2, which acquires ambient sound S (see Figure 2) of the drone 1 through a sound intake hole 7 drilled in the bottom of the body 2.

[0012] Figure 2 is a cross-sectional view showing the configuration of the microphone device 10. The microphone device 10 has a small module structure and acquires ambient sound S by removing the noise N emitted by the drone 1, specifically the noise (vibration) emitted by each motor 4, which consists of vibration noise (structure-borne sound) N1 transmitted from each motor 4 through the body 2 and mixed into the microphone device 10, and airborne noise (air-borne sound) N2 transmitted from each motor 4 through the air and mixed into the microphone device 10. The microphone device 10 comprises a microphone unit 20 and an acceleration sensor unit 30 arranged adjacent to the microphone unit 20 and coupled to the microphone unit 20.

[0013] The microphone unit 20 includes a microphone 21 that acquires ambient sound S of the drone 1, a microphone housing case 22 that forms the outer casing of the microphone unit 20 and encloses the microphone 21, and a sound introduction hole 23 drilled in the microphone housing case 22.

[0014] As the microphone 21, various microphones can be used, such as MESM microphones utilizing MEMS (Micro-Electro-Mechanical Systems) technology, electret condenser microphones (ECMs), and other sound-collecting elements.

[0015] The microphone 21 has a microphone substrate 211 made of a non-flexible rectangular rigid substrate (PCB) and a sound inlet hole 212. The microphone 21 shown in Figure 2 is a bottom-port type MESM microphone, and the sound inlet hole 212 is drilled in the microphone substrate (MESM substrate) 211.

[0016] The microphone housing case 22 is made of a soft material that is softer and more elastic than the material that makes up the microphone mounting section 2a of the drone 1, and is fixed to the microphone mounting section 2a.

[0017] The microphone installation part 2a is constituted by a part of the bottom of the body 2, and a sound introduction hole 7 is formed in the central part of the microphone installation part 2a. As the material of the body 2, metal or resin is used. Among metals, aluminum is often used, and among resins, polycarbonate, resin mixed with glass fiber, and resin mixed with carbon fiber are often used.

[0018] As the material of the microphone housing case 22, soft materials such as rubber, silicon, urethane, and elastomer with good vibration absorption rate can be used.

[0019] The microphone housing case 22 includes an upper case 221 with an open bottom surface and a lower case 222 with an open top surface. By combining the upper case 221 and the lower case 222, it is configured as a rectangular parallelepiped sealed box. The microphone housing case 22 houses the microphone 21 with the four side edges of the microphone substrate 211 sandwiched between the upper case 221 and the lower case 222. The upper case 221 and the lower case 222 are combined and assembled into the microphone housing case 22 by being adhered with an adhesive, for example.

[0020] The microphone housing case 22 has a device joining surface 223 along the shape of the microphone installation surface 2b of the microphone installation part 2a, and the device joining surface 223 is adhered in a state of being in close contact with the microphone installation surface 2b by, for example, double-sided tape or an adhesive. When the microphone installation surface 2b is configured as a flat surface, the device joining surface 223 is also configured as a flat surface accordingly. In the microphone housing case 22, the flat bottom surface (lower surface) of the lower case 222, which is its flat bottom surface, serves as the device joining surface 223.

[0021] The sound introduction hole 23 is formed in the central part of the device contact surface 223 so as to match the sound introduction hole 7 when the microphone housing case 22 is fixed to the microphone installation part 2a.

[0022] At the bottom of the lower case 222 which is the bottom of the microphone housing case 22, a sound introduction cylinder 231 extending vertically in a direction orthogonal to the device joint surface 223 is integrally formed. The lower end of the sound introduction cylinder 231 protruding downward from the device contact surface 223 is fitted inside the sound introduction hole 7, and the upper end of the sound introduction cylinder 231 extending upward from the device contact surface 223 and protruding into the interior of the lower case 222 abuts against the microphone substrate 211. The inner hole of the sound introduction cylinder 224 becomes the sound introduction hole 23, and the sound introduction hole 23 airtightly connects and communicates the sound introduction hole 7 and the sound introduction hole 212.

[0023] The acceleration sensor unit 30 includes an acceleration sensor 31 that acquires vibration noise N1 from each motor 4 transmitted through the body 2, an acceleration sensor substrate 32 on which the acceleration sensor 31 is mounted, and an acceleration sensor holding member 33 that holds the acceleration sensor substrate 32.

[0024] As the acceleration sensor 31, for example, various acceleration sensors (vibration sensors) such as a piezoelectric acceleration sensor, a MESM acceleration sensor using MEMS (Micro Electro Mechanical System) technology, and a capacitive acceleration sensor can be used. Also, a microphone 21 with the sound introduction hole closed can be used as the acceleration sensor 21.

[0025] The acceleration sensor substrate 32 is made of a rectangular rigid substrate (PCB) without flexibility, and the acceleration sensor holding member 33 is made of a hard material harder than the material constituting the acceleration sensor installation part 2c of the drone 1 and is fixed to the acceleration sensor installation part 2c.

[0026] The acceleration sensor installation part 2c is formed as a part of the bottom of the body 2 adjacent to the microphone installation part 2a. As the material of the acceleration sensor holding member 33, metals such as aluminum, steel, and stainless steel, resins such as ABS resin, acrylic, resin mixed with glass fiber, resin mixed with carbon fiber, and other materials such as glass and ceramic can be used to prevent vibration attenuation.

[0027] The acceleration sensor holding member 33 is formed in the shape of a tray (a shallow box-shaped container) having a rectangular bottom plate 331 and side walls 332 that rise from the four outer edges of the bottom plate 331, and holds the acceleration sensor substrate 32 fitted and housed inside the side walls 332.

[0028] In the microphone device 10, the acceleration sensor holding member 33 has a substrate bonding surface 333 that conforms to the shape of the non-mounted acceleration sensor surface 322 on the opposite side of the acceleration sensor mounting surface 321 of the acceleration sensor substrate 32, and an equipment bonding surface 334 that conforms to the shape of the acceleration sensor mounting surface 2d of the acceleration sensor mounting section 2c. The substrate bonding surface 333 is bonded to the non-mounted acceleration sensor surface 322 in close contact with, for example, double-sided tape or adhesive, and the equipment bonding surface 334 is bonded to the acceleration sensor mounting surface 2d in close contact with, for example, double-sided tape or adhesive.

[0029] An acceleration sensor 31 is mounted on the flat upper surface of the acceleration sensor substrate 32. The flat upper surface of the acceleration sensor substrate 32 is the acceleration sensor mounting surface 321, and the flat lower surface of the acceleration sensor substrate 32 is the non-acceleration sensor mounting surface 322. Since the non-acceleration sensor mounting surface 322 is a flat surface, the substrate bonding surface 333 is also a flat surface. In the acceleration sensor holding member 33, the upper surface of the bottom plate 331 is the substrate bonding surface 333.

[0030] If the acceleration sensor mounting surface 2d is a curved surface that is convex downwards, then the equipment connection surface 334 is also a curved surface that is convex downwards to match it. In the acceleration sensor holding member 33, the lower surface of the bottom plate 331 is the equipment connection surface 334.

[0031] The acceleration sensor unit 30 includes an acceleration sensor cover 34 that covers the acceleration sensor holding member 33 from above. The acceleration sensor cover 34, when combined with the acceleration sensor holding member 33, forms the outer casing of the acceleration sensor unit 30 and constitutes a rectangular parallelepiped acceleration sensor housing case 35 that encloses the acceleration sensor 31. The acceleration sensor housing case 35 houses the acceleration sensor 31 with the acceleration sensor substrate 32 fitted inside the acceleration sensor holding member 33. The acceleration sensor cover 34 and the acceleration sensor holding member 33 are assembled into the acceleration sensor housing case 35 by bonding them together, for example, with an adhesive.

[0032] The microphone device 10 includes a coupling portion 40 between the microphone unit 20 and the acceleration sensor unit 30. The coupling portion 40 consists of extensions 41 and 42 of the microphone housing case 22 and is made of the same material as the microphone housing case 22.

[0033] The extension 41 extends from the upper case 221 above the acceleration sensor holding member 33, covering the acceleration sensor holding member 33 entirely and forming the acceleration sensor cover 34. The extension 42 extends from the lower case 222 between the acceleration sensor holding member 33 and the acceleration sensor cover 34. The extensions 41 and 42 are bonded to the acceleration sensor holding member 33, for example, with an adhesive.

[0034] The microphone device 10 includes a connecting member 50 made of a flexible printed circuit board (FPC) that electrically connects the microphone 21 and the acceleration sensor board 32.

[0035] One end of the connecting member 50 is soldered to the microphone circuit board 211 inside the microphone housing case 22. The connecting member 50 is pulled from inside the microphone housing case 22 through the space between the extension 41, which is the acceleration sensor cover 34, and the extension 42, into the acceleration sensor housing case 35, and the other end of the connecting member 50 is soldered to the acceleration sensor circuit board 32.

[0036] Figure 3 is a block diagram showing the configuration of the signal processing unit 60 of the microphone device 10. The signal processing unit 60 shown in Figure 3 is equipped with a noise canceller 70. The signal processing unit 60 is configured, for example, by a digital signal processor (DSP). Based on the vibration noise (vibration noise signal) N1 acquired by the acceleration sensor 31, the noise canceller 70 generates a removed noise (removed noise signal) N3 that is correlated with the airborne noise (airborne noise signal) N2 that travels through the air from each motor 4 and enters the microphone 21, and outputs an ambient sound (ambient sound signal) S1 in which the airborne noise (airborne noise signal) N2 contained in the ambient sound (ambient sound signal) S acquired by the microphone 21 is removed by the removed noise (removed noise signal) N3.

[0037] The noise canceller 70 includes an adaptive filter 71 and a noise reduction circuit (subtractor) 72. The adaptive filter 71 receives vibration noise (vibration noise signal) N1 acquired by the acceleration sensor 31 and ambient sound (ambient sound signal) S1 obtained by the noise reduction circuit 72 by removing airborne noise (airborne noise signal) N2 contained in ambient sound (ambient sound signal) S acquired by the microphone 21. Using these vibration noise (vibration noise signal) N1 and ambient sound (ambient sound signal) S1, the noise reduction circuit 71 generates a removed noise (removed noise signal) N3 that correlates with the airborne noise (airborne noise signal) N2 transmitted from each motor 4 through the air and mixed into the microphone 21, and outputs this removed noise (removed noise signal) N3 to the noise reduction circuit 72. The noise reduction circuit 72 receives ambient sound (ambient sound signal) S acquired by the microphone 21, and generates and outputs ambient sound (ambient sound signal) S1 obtained by subtracting the removed noise N3 contained therein from this ambient sound (ambient sound signal) S.

[0038] The noise canceller 70 is mounted on the acceleration sensor board 32.

[0039] The microphone device 10 according to this embodiment is a microphone device mounted on a drone 1 (an example of equipment) having a motor 4 (an example of a noise source), and comprises a microphone unit 20 and an acceleration sensor unit 30. The microphone unit 20 comprises a microphone 21 that acquires ambient sound S of the drone 1, a microphone housing case 22 that forms the outer shell of the microphone unit 20 and encloses the microphone 21, and a sound introduction hole 23 drilled in the microphone housing case 22. The microphone housing case 22 is softer and more elastic than the material that constitutes the microphone mounting part 2a of the drone 1. The acceleration sensor unit 30 is made of a flexible soft material and is fixed to the microphone mounting section 2a. The acceleration sensor unit 30 includes an acceleration sensor 31 that acquires vibration noise N1 from the motor 4 transmitted through the body 2 (an example of the device itself), an acceleration sensor substrate 32 on which the acceleration sensor 31 is mounted, and an acceleration sensor holding member 33 that holds the acceleration sensor substrate 32. The acceleration sensor substrate 33 is made of a rigid substrate that does not have flexibility, and the acceleration sensor holding member 33 is made of a hard material that is harder than the material that makes up the acceleration sensor mounting section 2c of the drone 1 and is fixed to the acceleration sensor mounting section 2c.

[0040] According to the microphone device 10 of this embodiment, the microphone 21 is enclosed in a microphone housing case 22 made of a soft material that is softer and more elastic than the material constituting the microphone mounting section 2a of the drone 1, so that vibration noise N1 from the motor 4 that enters the microphone 21 can be removed. Furthermore, since the acceleration sensor 31 is held in an acceleration sensor holding member 33 made of a hard material that is harder than the material constituting the acceleration sensor mounting section 2c of the drone 1, vibration noise N1 from the motor 4 that is correlated with airborne noise N2 that travels from the motor 4 through the air and enters the microphone 21 can be acquired with high sensitivity, even if it is not placed near the motor 4. As a result, even in a drone 1 having multiple motors 4, it is not necessary to provide an acceleration sensor 31 for each motor 4, and the microphone 21 and acceleration sensor 31 can be placed in close proximity, enabling modularization of the microphone device 10.

[0041] According to this embodiment, a microphone device 10 can be provided that can acquire ambient sound S1 with the noise N generated by the drone 1 removed by the module structure.

[0042] In the microphone device 10 according to this embodiment, the acceleration sensor holding member 33 has a substrate bonding surface 333 that conforms to the shape of the non-mounted acceleration sensor surface 322 on the opposite side of the acceleration sensor mounting surface 321 of the acceleration sensor substrate 32, and an equipment bonding surface 334 that conforms to the shape of the acceleration sensor mounting surface 2d of the acceleration sensor mounting section 2c. The substrate bonding surface 333 is bonded in close contact with the non-mounted acceleration sensor surface 322, and the equipment bonding surface 334 is bonded in close contact with the acceleration sensor mounting surface 2d. This prevents attenuation of vibration noise between the acceleration sensor holding member 33 and the acceleration sensor substrate 32, and between the acceleration sensor mounting section 2c and the acceleration sensor holding member 33, that is, between the body 2 and the acceleration sensor 21.

[0043] In the microphone device 10 according to this embodiment, a coupling portion 40 is provided between the microphone unit 20 and the acceleration sensor unit 30. The coupling portion 40 consists of extensions 41 and 42 of the microphone housing case 22 and is made of the same material as the microphone housing case 22, which prevents vibration noise N1 from the motor 4 from entering the microphone 21 from the acceleration sensor unit 30 through the coupling portion 40.

[0044] In the microphone device 10 according to this embodiment, a connecting member 50 is provided to electrically connect the microphone 21 and the acceleration sensor substrate 32. The connecting member 50 is a flexible substrate, which prevents vibration noise N1 from the motor 4 from entering the microphone 21 from the acceleration sensor substrate 32 via the connecting member 50.

[0045] The microphone device 10 according to this embodiment includes a noise canceller 70 that generates a noise reduction noise N3 correlated with airborne noise N2 transmitted from the motor 4 through the air and mixed into the microphone 21, based on vibration noise N1 acquired by the acceleration sensor 31, and removes the airborne noise N2 included in the ambient sound S acquired by the microphone 21 with the noise reduction noise N3.

[0046] In this embodiment, the microphone device 10 has the noise canceller 70 mounted on the acceleration sensor substrate 32. Compared to the case where the noise canceller 70 is mounted on another substrate such as the microphone substrate 211, the area of ​​the acceleration sensor substrate 32 and the acceleration sensor holding member 32 can be effectively utilized, and the vibration noise N1 from the motor 4 can be transmitted to the acceleration sensor 31 more reliably.

[0047] The present invention is not limited to this embodiment, and various modifications are possible without departing from its spirit. For example, the electrical connection between the microphone and the acceleration sensor substrate can be any connection structure that can attenuate vibrations while making an electrical connection, such as conductive rubber. A relay connection board may be interposed between the electrical connection between the microphone and the acceleration sensor substrate. The microphone and acceleration sensor do not need to be integrated; any connection that does not transmit vibrations is acceptable as long as their installation locations are close together.

[0048] In addition to drones, this invention can be used to acquire ambient sound after removing noise generated by equipment such as construction vehicles, agricultural machinery, motorcycles, automobiles, and digital video cameras, in installation situations where vibrations from the engines or motors of the equipment are transmitted. [Explanation of Symbols]

[0049] 1. Drone (an example of equipment) 2. Body (an example of the device itself) 2a Microphone mounting section 2b Microphone mounting surface 2c Accelerometer installation section 2D accelerometer mounting surface 4. Motors (an example of a noise source) 10 Microphone equipment 20 Microphone section 21 Microphone 22 Microphone storage case 23 sound introduction holes 30 Acceleration sensor section 31. Accelerometer 32 Accelerometer board 321 Accelerometer mounting surface 322 Accelerometer-less surface 33 Accelerometer holding member 333 Substrate bonding surface 334 Equipment joint surface 40 Joint 41, 42 extension 50 Connecting Members 60 Signal Processing Unit 70 Noise Canceller 71 Adaptive Filters 72 Noise Reduction Circuit S Ambient sound S1 Ambient sound with noise removed N Noise N1 Vibration and Noise N2 airborne noise

Claims

1. A microphone device mounted on equipment having a noise source, It comprises a microphone unit and an acceleration sensor unit. The microphone unit comprises a microphone for acquiring ambient sound of the device, a microphone housing case that forms the outer casing of the microphone unit and encloses the microphone, and a sound introduction hole drilled in the microphone housing case. The microphone housing case is made of a soft material that is softer and more elastic than the material that constitutes the microphone mounting section of the device, and is fixed to the microphone mounting section. The microphone device is characterized in that the acceleration sensor unit comprises an acceleration sensor that acquires vibration noise from the noise source transmitted through the device itself, an acceleration sensor substrate on which the acceleration sensor is mounted, and an acceleration sensor holding member that holds the acceleration sensor substrate, wherein the acceleration sensor substrate is made of a rigid substrate that does not have flexibility, and the acceleration sensor holding member is made of a hard material that is harder than the material constituting the acceleration sensor mounting part of the device and is fixed to the acceleration sensor mounting part.

2. The microphone device according to claim 1, wherein the acceleration sensor holding member has a substrate bonding surface that conforms to the shape of the non-mounted surface of the acceleration sensor substrate and an equipment bonding surface that conforms to the shape of the acceleration sensor mounting surface of the acceleration sensor mounting portion, the substrate bonding surface is bonded in close contact with the non-mounted surface of the acceleration sensor, and the equipment bonding surface is bonded in close contact with the acceleration sensor mounting surface.

3. The microphone device according to claim 1, comprising a coupling portion between the microphone portion and the acceleration sensor portion, wherein the coupling portion is an extension of the microphone housing case.

4. The microphone device according to claim 1, further comprising a connecting member for electrically connecting the microphone and the acceleration sensor substrate, wherein the connecting member is a flexible substrate having flexibility.

5. The microphone device according to claim 1, further comprising a noise canceller that generates a noise reduction noise correlated with airborne noise transmitted from the noise source through the air and mixed into the microphone, based on vibration noise acquired by the acceleration sensor, and removes the airborne noise included in the ambient sound acquired by the microphone with the noise reduction noise.

6. The microphone device according to claim 5, characterized in that the noise canceller is mounted on the acceleration sensor substrate.

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