Microphone device

Abstract

To provide a microphone device capable of performing digital signal processing while suppressing an increase in latency.SOLUTION: A microphone device 10 comprises: a housing 20 that includes an open part 200 and a horn 211 containing a horn open part 231 and a horn pipe 241 to be extended to a one direction from the horn open part 231; a microphone that converts a sound propagated through the open part 200 into an analog signal; a horn microphone 40 that converts a sound propagated through the horn 211 into an analog signal; an analog wiring 45 that outputs the analog signal from the horn microphone 40; an ADC chip 50 that acquires the analog signal from the horn microphone 40 via a wiring that is different from the analog wiring 45, and converts the analog signal from the microphone and the horn microphone 40 into a digital signal; and a processing part that performs digital signal processing to the digital signal converted by the ADC chip 50.SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

[0002] Conventionally, as described in Patent Document 1, there is known an acoustic system including a plurality of acoustic ports, acoustic passages connected to the respective acoustic ports, and a capsule that converts an acoustic signal propagated from a sound source through the acoustic ports and the acoustic passages into an electric signal.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the acoustic system described in Patent Document 1, digital signal processing such as noise reduction may be performed on the electric signal converted by the capsule. In this case, the latency, which is the communication delay time, increases. When the latency increases, for example, the speaking timings of a call overlap, making the call difficult and thus degrading the call quality. Also, if digital signal processing is not performed, the call becomes difficult due to noise, degrading the call quality.

[0005] An object of the present disclosure is to provide a microphone device that performs digital signal processing while suppressing an increase in latency.

Means for Solving the Problems

[0006] The invention according to claim 1 has a housing (20) having an open opening (200), a horn (211) formed at a position different from the opening and having an open horn opening (231) and a horn tube (241) connected to the horn opening and extending in one direction, a microphone (35) housed in the housing and converting the sound propagated through the opening into an analog signal, a horn microphone (40) housed in the housing and converting the sound propagated through the horn into an analog signal, an analog wiring (45) housed in the housing and outputting the analog signal from the horn microphone, a conversion unit (50) that acquires the analog signal from the microphone and acquires the analog signal from the horn microphone via a wiring (55) different from the analog wiring, and converts the analog signals from the microphone and the horn microphone into digital signals, and a processing unit (60) that performs digital signal processing on the digital signal converted by the conversion unit.

[0007] The signal output from the analog wiring is not digitally signal-processed, so it is a signal with suppressed increase in latency. Also, digital signal processing is performed in the processing unit. Therefore, the microphone device performs digital signal processing while suppressing an increase in latency.

[0008] Note that the reference numerals in parentheses attached to each component etc. show an example of the correspondence relationship between the component etc. and the specific components etc. described in the embodiments described later.

Brief Description of Drawings

[0009]

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Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments will be described with reference to the drawings. In the following embodiments, parts that are identical or equivalent to each other are denoted by the same reference numerals, and their descriptions are omitted.

[0011] (First Embodiment) The microphone device of this embodiment performs digital signal processing while suppressing an increase in latency. This microphone device is used, for example, in a vehicle.

[0012] Specifically, as shown in FIGS. 1 to 11, the microphone device 10 includes a housing 20, a substrate 30, an isolator 32, a microphone 35, a horn microphone 40, an analog wiring 45, an ADC chip 50, a digital wiring 55, and a processing unit 60.

[0013] The housing 20 is formed of resin or the like using injection molding, a 3D printer, or the like. Further, as shown in FIGS. 1 to 8, the housing 20 houses the substrate 30, the microphone 35, the horn microphone 40, the analog wiring 45, the ADC chip 50, the digital wiring 55, and the processing unit 60, which will be described later. Furthermore, the housing 20 has an opening 200 and a directivity generator 210.

[0014] Here, in order to describe the housing 20 and the like, a Cartesian coordinate system with a position inside or outside the microphone device 10 as a reference is defined as an absolute coordinate system. Also, the X-axis, Y-axis, and Z-axis in the absolute coordinate system are orthogonal to each other. Furthermore, the absolute coordinate system is represented by a right-handed system. Also, the directions of the arrows in the figures are defined as the positive directions of the X-axis, Y-axis, and Z-axis. Furthermore, the directions opposite to the directions of the arrows in the figures are defined as the negative directions of the X-axis, Y-axis, and Z-axis.

[0015] As shown in FIGS. 2 to 8, a plurality of openings 200 are formed. Here, the opening 200 opens in the positive direction of the Z-axis. Furthermore, the space of the opening 200 extends in the Z-axis direction.

[0016] As shown in FIGS. 2 to 11, the directivity generator 210 includes a first horn 211, a second horn 212, a third horn 213, a fourth horn 214, a first acoustic tube 221, a second acoustic tube 222, a third acoustic tube 223, and a fourth acoustic tube 224. Thereby, as will be described later, the directivity generator 210 generates directivity for the sound collected by the microphone device 10. Here, the directivity refers to the property that the ease of sound collection varies depending on the direction.

[0017] The first horn 211, the second horn 212, the third horn 213, and the fourth horn 214 are, for example, exponential horns. Note that the first horn 211, the second horn 212, the third horn 213, and the fourth horn 214 are not limited to being exponential horns, and may be cylindrical horns, parabolic horns, conical horns, hyperbolic horns, or the like.

[0018] Also, as shown in FIGS. 2 to 5, FIGS. 9, and 10, the first horn 211 includes a first horn opening 231 and a first horn tube 241.

[0019] The first horn opening 231 is formed at a position different from the opening 200. Further, here, the first horn opening 231 opens in the positive direction of the Z axis.

[0020] The first horn tube 241 is connected to the first horn opening 231. Also, the first horn tube 241 extends in one direction, here, the negative direction of the Z axis, from the first horn opening 231. Further, the first horn 211 is an exponential horn. For this reason, the cross-sectional area of the first horn tube 241 when cut in a direction orthogonal to the one direction increases as it goes from the side opposite to the first horn opening 231 to the first horn opening 231 side in the first horn tube 241. Here, the cross-sectional area of the first horn tube 241 when cut in the direction orthogonal to the Z axis, that is, in the XY plane, increases as it goes in the positive direction of the Z axis.

[0021] As shown in FIGS. 2 to 4, 6, and 9 to 11, the second horn 212 includes a second horn opening 232 and a second horn tube 242.

[0022] The second horn opening 232 is formed at a position different from the opening 200 and the first horn opening 231. Further, the second horn opening 232 opens in the direction in which the first horn opening 231 opens, here, in the positive direction of the Z axis.

[0023] The second horn tube 242 is connected to the second horn opening 232. Also, the second horn tube 242 extends in one direction from the second horn opening 232, here, in the negative direction of the Z axis. Further, the second horn 212 is an exponential horn. For this reason, the cross-sectional area of the second horn tube 242 when cut in a direction orthogonal to the one direction increases as it goes from the side opposite to the second horn opening 232 to the second horn opening 232 side in the second horn tube 242. Here, the cross-sectional area of the second horn tube 242 when cut in the direction orthogonal to the Z axis, that is, in the X-axis or Y-axis direction, increases as it goes in the positive direction of the Z axis.

[0024] As shown in FIGS. 2, 3, 5, 7, and 9, the third horn 213 includes a third horn opening 233 and a third horn tube 243.

[0025] The third horn opening 233 is formed at a position different from the opening 200, the first horn opening 231, and the second horn opening 232. Further, the third horn opening 233 opens in the direction in which the first horn opening 231 and the second horn opening 232 open, here, in the positive direction of the Z axis.

[0026] The third horn tube 243 is connected to the third horn opening 233. Also, the third horn tube 243 extends in one direction from the third horn opening 233, here in the negative direction of the Z axis. Further, the third horn 213 is an exponential horn. For this reason, the cross-sectional area of the third horn tube 243 when cut in a direction orthogonal to the one direction becomes larger as it goes from the side opposite to the third horn opening 233 to the third horn opening 233 side in the third horn tube 243. Here, the cross-sectional area of the third horn tube 243 when cut in a direction orthogonal to the Z axis, that is, in the X-axis or Y-axis direction, becomes larger as it goes in the positive direction of the Z axis.

[0027] The fourth horn 214 includes a fourth horn opening 234 and a fourth horn tube 244 as shown in FIGS. 2, 3, 6, 7, and 11.

[0028] The fourth horn opening 234 is formed at a position different from the opening 200, the first horn opening 231, the second horn opening 232, and the third horn opening 233. Further, the fourth horn opening 234 opens facing the positive direction of the Z axis, which is the direction in which the first horn opening 231, the second horn opening 232, and the third horn opening 233 open.

[0029] The fourth horn tube 244 is connected to the fourth horn opening 234. Also, the fourth horn tube 244 extends in one direction from the fourth horn opening 234, here in the negative direction of the Z axis. Further, the fourth horn 214 is an exponential horn. For this reason, the cross-sectional area of the fourth horn tube 244 when cut in a direction orthogonal to the one direction becomes larger as it goes from the side opposite to the fourth horn opening 234 to the fourth horn opening 234 side in the fourth horn tube 244. Here, the cross-sectional area of the fourth horn tube 244 when cut in a direction orthogonal to the Z axis, that is, in the X-axis or Y-axis direction, becomes larger as it goes in the positive direction of the Z axis.

[0030] Further, as shown in FIGS. 2 to 4, FIGS. 9 and 10, the first horn 211 and the second horn 212 are arranged in a direction orthogonal to one direction, here, in the Y-axis direction. Further, as shown in FIGS. 2, 3, 5 and 9, the first horn 211 and the third horn 213 are arranged in a direction orthogonal to one direction and the direction in which the first horn 211 and the second horn 212 are arranged, here, in the X-axis direction. Also, as shown in FIGS. 2, 3, 6, 9 and 11, the second horn 212 and the fourth horn 214 are arranged in a direction orthogonal to one direction and the direction in which the first horn 211 and the second horn 212 are arranged, here, in the X-axis direction. Further, as shown in FIGS. 2, 3, 7 and 9, the third horn 213 and the fourth horn 214 are arranged in the direction in which the first horn 211 and the second horn 212 are arranged, here, in the Y-axis direction.

[0031] Also, the first horn 211, the second horn 212, the third horn 213 and the fourth horn 214 are here formed in the same shape and the same size. Here, the same includes the manufacturing error range. Further, the first horn 211, the second horn 212, the third horn 213 and the fourth horn 214 are not limited to being formed in the same shape and the same size, and may be of different shapes and different sizes respectively.

[0032] The first acoustic tube 221 is formed in a cylindrical shape as shown in FIGS. 2, 4 to 6, FIGS. 8 to 11, and is connected to the first horn tube 241 and the second horn tube 242 in the Z-axis direction. Also, the first acoustic tube 221 extends in a direction intersecting one direction, here, in the Y-axis direction.

[0033] As shown in FIGS. 2, 5, 6, 8, 9, and 11, the second acoustic tube 222 is formed in a cylindrical shape and is connected to the third horn tube 243 and the fourth horn tube 244 in the Z-axis direction. Further, the second acoustic tube 222 extends in the Y-axis direction here, parallel to the direction in which the first acoustic tube 221 extends. Also, the second acoustic tube 222 is formed in the same shape and the same size as the first acoustic tube 221. Note that the second acoustic tube 222 is not limited to being formed in the same shape and the same size, and may be formed in a different shape and a different size from the first acoustic tube 221.

[0034] As shown in FIGS. 2, 4, 7 to 11, the third acoustic tube 223 is formed in a cylindrical shape and is connected to the first acoustic tube 221 and the second acoustic tube 222 in the Z-axis direction. Further, the third acoustic tube 223 extends in the X-axis direction here, in a direction intersecting one direction and the direction in which the first acoustic tube 221 extends. Therefore, the first acoustic tube 221, the second acoustic tube 222, and the third acoustic tube 223 form an H-shaped acoustic tube.

[0035] As shown in FIGS. 2, 8 to 11, the fourth acoustic tube 224 is formed in a cylindrical shape and is connected to the portion between the first acoustic tube 221 and the second acoustic tube 222 in the third acoustic tube 223 in the Z-axis direction. Also, the fourth acoustic tube 224 extends in a direction intersecting the direction in which the third acoustic tube 223 extends. Here, it extends in the negative Z-axis direction from the third acoustic tube 223. Note that the fourth acoustic tube 224 is not limited to extending in the Z-axis direction from the third acoustic tube 223, and may extend in the Y-axis direction or the like from the third acoustic tube 223.

[0036] The substrate 30 is a printed circuit board. Further, as shown in FIGS. 2, 4 to 8, the substrate 30 is housed in the housing 20. Also, the substrate 30 is fixed to the housing 20 via, for example, snap fits, screws (not shown), and the isolator 32 described later. Further, the thickness direction of the substrate 30 coincides with the Z-axis direction. Also, as shown in FIGS. 4 to 8, the substrate 30 has a substrate surface 300, a substrate back surface 302, and a substrate hole 304.

[0037] The substrate surface 300 is a surface of the substrate 30 that is orthogonal to the thickness direction of the substrate 30, and here it is located on the positive direction side of the Z-axis.

[0038] The back surface 302 of the substrate is a surface of the substrate 30 that is opposite to the substrate surface 300, and here it is located on the negative direction side of the Z-axis.

[0039] The substrate holes 304 are formed at positions corresponding to the positions of the openings 200. For this reason, the number of substrate holes 304 corresponds to the number of openings 200. Further, the substrate holes 304 communicate with the space of the openings 200. Also, the substrate holes 304 extend in the Z-axis direction and penetrate the substrate surface 300 and the back surface 302 of the substrate.

[0040] The isolator 32 is disposed between the housing 20 and the substrate surface 300. Also, the isolator 32 is formed of an elastic body such as closed-cell sponge, rubber, foamed rubber, clay, or an adhesive. Further, the isolator 32 prevents sound entering from a certain opening 200 from propagating between the housing 20 and the substrate surface 300 and the propagated sound from propagating to a microphone 35 other than the microphone 35 described later located directly below the opening 200. Also, the isolator 32 prevents vibrations transmitted from the housing 20 from being propagated through the substrate 30 and being observed by the microphone 35.

[0041] The microphone 35 is connected to the vicinity of the position of the substrate hole 304 on the back surface 302 of the substrate. Therefore, the number of microphones 35 corresponds to the number of the openings 200 and the substrate holes 304. Further, the microphone 35 is housed in the housing 20. Also, the microphone 35 converts the sound propagated through the openings 200 and the substrate holes 304 into an analog signal. Note that the analog signal is a signal representing a continuously changing physical quantity, and here, it is an electrical signal such as a current or a voltage corresponding to sound. Note that the microphone 35 may be a microphone having a sound hole for taking in sound from the side opposite to the surface on which it is mounted on the substrate 30. That is, the microphone 35 may be mounted between the substrate 30 and the housing 20 on the substrate surface 300 and arranged at a position where the opening 200 and the sound hole of the microphone 35 correspond to each other.

[0042] As shown in FIGS. 2 and 8, the horn microphone 40 is connected to the fourth acoustic tube 224. Further, the horn microphone 40 is housed in the housing 20. Also, the horn microphone 40 converts the sound propagated through the first horn 211, the first acoustic tube 221, the third acoustic tube 223, and the fourth acoustic tube 224 into an analog signal. Further, the horn microphone 40 converts the sound propagated through the second horn 212, the first acoustic tube 221, the third acoustic tube 223, and the fourth acoustic tube 224 into an analog signal. Also, the horn microphone 40 converts the sound propagated through the third horn 213, the second acoustic tube 222, the third acoustic tube 223, and the fourth acoustic tube 224 into an analog signal. Further, the horn microphone 40 converts the sound propagated through the fourth horn 214, the second acoustic tube 222, the third acoustic tube 223, and the fourth acoustic tube 224 into an analog signal.

[0043] The analog wiring 45 is connected to the horn microphone 40. Also, the analog wiring 45 is housed in the housing 20. Further, the analog wiring 45 outputs the analog signal from the horn microphone 40 to the outside of the microphone device 10.

[0044] The ADC chip 50 corresponds to the conversion unit and is mounted on the substrate surface 300. Therefore, the ADC chip 50 is housed in the housing 20. Also, the ADC chip 50 is connected to the microphone 35 via wiring and vias (not shown) on the substrate 30. Accordingly, the ADC chip 50 acquires the analog signal from the microphone 35 via the wiring and vias (not shown) on the substrate 30. Further, the ADC chip 50 is connected to the horn microphone 40 via the wiring and vias (not shown) on the substrate 30 and the digital wiring 55. Thus, the ADC chip 50 acquires the analog signal from the horn microphone 40 via the wiring and vias (not shown) on the substrate 30 and the digital wiring 55.

[0045] Also, as shown in FIG. 1, the ADC chip 50 has converters 500 corresponding to the microphone 35 and the horn microphone 40, respectively. Each converter 500 is a circuit that converts an analog signal into a digital signal. By means of each converter 500, the ADC chip 50 converts the analog signals from the microphone 35 and the horn microphone 40 into digital signals. Note that ADC is an abbreviation for Analog to Digital Converter. A digital signal is a signal that has been discretized with respect to variables such as time and measured values such as current and voltage. Discretization means converting an analog signal into discrete values.

[0046] The processing unit 60 is mainly composed of a microcomputer or the like, and includes a CPU, a ROM, a flash memory, a RAM, an I / O, and a bus line connecting these components. Also, as shown in FIG. 8, the processing unit 60 is mounted on the back surface 302 of the substrate, for example. Further, the processing unit 60 is connected to the ADC chip 50 via wiring and vias (not shown) on the substrate 30.

[0047] Further, the processing unit 60 performs digital signal processing on the digital signal converted by the ADC chip 50. For example, the processing unit 60 performs sound source separation such as BSS using ICA, PCA, etc. on the digital signal converted by the ADC chip 50. Thereby, the processing unit 60 makes the noise included in the digital signal converted by the ADC chip 50 smaller than the noise included in the analog signal from the horn microphone 40. Further, the processing unit 60 outputs the signal after digital signal processing to the outside of the microphone device 10 via wiring (not shown) or the like. Note that ICA is the abbreviation of Independent Component Analysis. PCA is the abbreviation of Principal Component Analysis. BSS is the abbreviation of Blind Source Separation. Also, the noise here is unnecessary sound information or undesirable sound information.

[0048] As described above, the microphone device 10 is configured. Next, the generation of directivity by the directivity generator 210 will be described.

[0049] Here, as shown in FIGS. 9 to 11, let the distance from the center of the connection portion of the first horn 211 and the first acoustic tube 221 to the center of the connection portion of the first acoustic tube 221 and the third acoustic tube 223 in the Y-axis direction be a1. Let the distance from the center of the connection portion of the second horn 212 and the first acoustic tube 221 to the center of the connection portion of the first acoustic tube 221 and the third acoustic tube 223 in the Y-axis direction be a2. Let the distance from the center of the connection portion of the first acoustic tube 221 and the third acoustic tube 223 to the center of the connection portion of the third acoustic tube 223 and the fourth acoustic tube 224 in the X-axis direction be b1. Let the distance from the center of the connection portion of the second acoustic tube 222 and the third acoustic tube 223 to the center of the connection portion of the third acoustic tube 223 and the fourth acoustic tube 224 in the X-axis direction be b2.

[0050] And the distance from the center of the connection point of the third horn 213 and the second acoustic tube 222 to the center of the connection point of the second acoustic tube 222 and the third acoustic tube 223 in the Y-axis direction is defined as a1. Further, the distance from the center of the connection point of the fourth horn 214 and the second acoustic tube 222 to the center of the connection point of the second acoustic tube 222 and the third acoustic tube 223 in the Y-axis direction is defined as a2.

[0051] Also, here, as shown in FIG. 12, in the YZ plane, assuming that a sound wave of a plane wave reaches the first horn 211 and the second horn 212 from a direction forming a first angle θ with the Z-axis. Here, the first angle θ is set to -90° ≤ θ ≤ 90°. Let the speed of sound be c. The position of the center of the projection when the center of the connection point of the first acoustic tube 221 and the third acoustic tube 223 is projected onto a plane orthogonal to the Z-axis while passing through the first horn opening 231 and the second horn opening 232 is defined as the first projection position P1.

[0052] At this time, the sound wave reaching the first horn 211 is shifted in time by (-a1 / c)×sinθ with respect to the sound wave reaching the first projection position P1, and here, it reaches earlier.

[0053] Also, the sound wave reaching the second horn 212 is shifted in time by (a2 / c)×sinθ with respect to the sound wave reaching the first projection position P1, and here, it reaches later.

[0054] Furthermore, the sound wave reaching the first horn 211 propagates through the first horn 211 and reaches the center of the connection point of the first horn 211 and the first acoustic tube 221. Also, the sound wave reaching the second horn 212 propagates through the second horn 212 and reaches the center of the connection point of the second horn 212 and the first acoustic tube 221. Further, here, since the first horn 211 and the second horn 212 have the same shape and the same size, the lengths of the first horn 211 and the second horn 212 in the Z-axis direction are the same. For this reason, no time shift occurs between the sound waves propagating through the first horn 211 and the second horn 212 due to the lengths of the first horn 211 and the second horn 212 in the Z-axis direction.

[0055] Also, the sound wave that reaches the center of the connection point between the first horn 211 and the first acoustic tube 221 propagates through the first acoustic tube 221 and reaches the center of the connection point between the first acoustic tube 221 and the third acoustic tube 223. The time it takes for the sound wave to reach from the center of the connection point between the first horn 211 and the first acoustic tube 221 to the center of the connection point between the first acoustic tube 221 and the third acoustic tube 223 is a1 / c.

[0056] Furthermore, the sound wave that reaches the center of the connection point between the second horn 212 and the first acoustic tube 221 propagates through the first acoustic tube 221 and reaches the center of the connection point between the first acoustic tube 221 and the third acoustic tube 223. The time it takes for the sound wave to reach from the center of the connection point between the second horn 212 and the first acoustic tube 221 to the center of the connection point between the first acoustic tube 221 and the third acoustic tube 223 is a2 / c.

[0057] Also, the sound wave that reaches the center of the connection point between the first acoustic tube 221 and the third acoustic tube 223 propagates through the third acoustic tube 223 and the fourth acoustic tube 224 and reaches the horn microphone 40. Since the paths of the sound waves are common, there is no time shift in the sound waves reaching the horn microphone 40 from the center of the connection point between the first acoustic tube 221 and the third acoustic tube 223.

[0058] Therefore, the time shift of the sound wave that propagates through the first horn 211, the first acoustic tube 221, the third acoustic tube 223, and the fourth acoustic tube 224 and reaches the horn microphone 40 is (-a1 / c)×sinθ+(a1 / c). Furthermore, the time shift of the sound wave that propagates through the second horn 212 and the first acoustic tube 221 and reaches the center of the connection point between the first acoustic tube 221 and the third acoustic tube 223 is (a2 / c)×sinθ+(a2 / c).

[0059] When these time shifts are the same, the respective sound waves reinforce each other in the entire frequency range. At this time, the first angle θ is expressed using a1 and a2 as in the following relational expression (1). Therefore, the directivity on the YZ plane is generated by a1 and a2.

[0060] (-a1 / c)×sinθ+(a1 / c)=(a2 / c)×sinθ+(a2 / c) sinθ=(a1 - a2) / (a1 + a2) θ = arcsin{(a1 - a2) / (a1 + a2)} ···(1)

[0061] In addition, in the above calculation, it is not limited that the lengths of the first horn 211 and the second horn 212 in the Z-axis direction are the same. The lengths of the first horn 211 and the second horn 212 in the Z-axis direction may be different, and the time shift due to the lengths of the first horn 211 and the second horn 212 in the Z-axis direction may also be considered.

[0062] Also, in the case of the third horn 213 and the fourth horn 214, similar to the case of the first horn 211 and the second horn 212, the directivity on the YZ plane is generated by a1 and a2. Also in this case, it is not limited that the lengths of the third horn 213 and the fourth horn 214 in the Z-axis direction are the same. The lengths of the third horn 213 and the fourth horn 214 in the Z-axis direction may be different, and the time shift due to the lengths of the third horn 213 and the fourth horn 214 in the Z-axis direction may also be considered.

[0063] Also, here, as shown in FIG. 13, in the XZ plane, assuming that a sound wave of a plane wave reaches the first horn 211 and the third horn 213 from a direction forming a second angle φ with the Z-axis. Here, the second angle φ is set to -90° ≤ θ ≤ 90°. Let the speed of sound be c. The position of the center of the connection portion of the third acoustic tube 223 and the fourth acoustic tube 224 projected onto a plane perpendicular to the Z-axis while passing through the first horn opening 231 and the third horn opening 233 is defined as the second projection position P2.

[0064] At this time, the sound wave reaching the first horn 211 is delayed by (b1 / c)×sinφ with respect to the sound wave reaching the second projection position P2, and here, it reaches later.

[0065] In addition, the sound wave reaching the third horn 213 is shifted in time by (-b2 / c)×sinφ with respect to the sound wave reaching the second projection position P2, and here, it reaches earlier.

[0066] Furthermore, the sound wave reaching the first horn 211 propagates through the first horn 211 and reaches the center of the connection point between the first horn 211 and the first acoustic tube 221. Also, the sound wave reaching the third horn 213 propagates through the third horn 213 and reaches the center of the connection point between the third horn 213 and the second acoustic tube 222. Furthermore, here, since the first horn 211 and the third horn 213 have the same shape and the same size, the lengths of the first horn 211 and the third horn 213 in the Z-axis direction are the same. Therefore, due to the lengths of the first horn 211 and the third horn 213 in the Z-axis direction, no time shift occurs between the sound waves propagating through the first horn 211 and the third horn 213.

[0067] Also, the sound wave reaching the center of the connection point between the first horn 211 and the first acoustic tube 221 propagates through the first acoustic tube 221 and passes through the center of the connection point between the first acoustic tube 221 and the third acoustic tube 223. Furthermore, the sound wave reaching the center of the connection point between the third horn 213 and the second acoustic tube 222 propagates through the second acoustic tube 222 and passes through the center of the connection point between the second acoustic tube 222 and the third acoustic tube 223. Also, here, the distance in the Y-axis direction from the center of the connection point between the first horn 211 and the first acoustic tube 221 to the center of the connection point between the first acoustic tube 221 and the third acoustic tube 223 is set as a1. The distance in the Y-axis direction from the center of the connection point between the third horn 213 and the second acoustic tube 222 to the center of the connection point between the second acoustic tube 222 and the third acoustic tube 223 is also set as a1. Therefore, the distances of both are the same. For this reason, no time shift occurs between the sound waves propagating through them.

[0068] Furthermore, the sound wave that reaches the center of the connection point between the first acoustic tube 221 and the third acoustic tube 223 propagates through the third acoustic tube 223 and reaches the center of the connection point between the third acoustic tube 223 and the fourth acoustic tube 224. The time it takes for the sound wave to reach from the center of the connection point between the first acoustic tube 221 and the third acoustic tube 223 to the center of the connection point between the third acoustic tube 223 and the fourth acoustic tube 224 is b1 / c.

[0069] Also, the sound wave that reaches the center of the connection point between the second acoustic tube 222 and the third acoustic tube 223 propagates through the third acoustic tube 223 and reaches the center of the connection point between the third acoustic tube 223 and the fourth acoustic tube 224. The time it takes for the sound wave to reach from the center of the connection point between the second acoustic tube 222 and the third acoustic tube 223 to the center of the connection point between the third acoustic tube 223 and the fourth acoustic tube 224 is b2 / c.

[0070] Furthermore, the sound wave that reaches the center of the connection point between the third acoustic tube 223 and the fourth acoustic tube 224 propagates through the fourth acoustic tube 224 and reaches the horn microphone 40. Since the sound wave paths are common, there is no time difference in the sound waves reaching the horn microphone 40 from the center of the connection point between the third acoustic tube 223 and the fourth acoustic tube 224.

[0071] Therefore, the time difference in the sound waves that propagate through the first horn 211, the first acoustic tube 221, the third acoustic tube 223, and the fourth acoustic tube 224 and reach the horn microphone 40 is (b1 / c)×sinφ+(b1 / c). Also, the time difference in the sound waves that propagate through the third horn 213, the second acoustic tube 222, the third acoustic tube 223, and the fourth acoustic tube 224 and reach the horn microphone 40 is (-b2 / c)×sinφ+(b2 / c).

[0072] When these time differences are the same, the respective sound waves reinforce each other in the full frequency range. At this time, the second angle φ is expressed using b1 and b2 as in the following relational expression (2). Therefore, the directivity on the XZ plane is generated by b1 and b2.

[0073] (b1 / c)×sinφ+(b1 / c)=(-b2 / c)×sinφ+(b2 / c) sinφ=(-b1 + b2) / (b1 + b2) φ = arcsin{(-b1 + b2) / (b1 + b2)} ···(2)

[0074] Note that in the above calculation, it is not limited that the lengths of the first horn 211 and the third horn 213 in the Z-axis direction are the same. The lengths of the first horn 211 and the third horn 213 in the Z-axis direction may be different, and the time shift due to the lengths of the first horn 211 and the third horn 213 in the Z-axis direction may also be considered.

[0075] Also, in the case of the second horn 212 and the fourth horn 214, similar to the case of the first horn 211 and the third horn 213, the directivity on the XZ plane is generated by b1 and b2. Also in this case, it is not limited that the lengths of the second horn 212 and the fourth horn 214 in the Z-axis direction are the same. The lengths of the second horn 212 and the fourth horn 214 in the Z-axis direction may be different, and the time shift due to the lengths of the second horn 212 and the fourth horn 214 in the Z-axis direction may also be considered.

[0076] Here, for example, let a1 = a2 = b1 = b2 = 20 mm. In this case, as shown in FIGS. 14, 15, and 16, although the directivity pattern varies depending on the frequency of the sound wave, when the first angle θ and the second angle φ are 0°, the gain of the sound wave collected by the horn microphone 40 is relatively high. Therefore, in this case, a directivity is generated in the direction in which the sound waves at 0° for the first angle θ and the second angle φ reinforce each other at all frequencies. Note that FIG. 14 shows a distribution indicating the relationship between the first angle θ, the second angle φ, and the gain of the sound wave collected by the horn microphone 40 when the frequencies of the sound waves are 10 kHz, 5 kHz, 2 kHz, and 1 kHz. FIG. 15 shows the relationship between the second angle φ and the gain of the sound wave collected by the horn microphone 40 when the first angle θ is fixed and the frequencies of the sound waves are 20 kHz, 10 kHz, 5 kHz, 2 kHz, and 1 kHz. FIG. 16 shows a distribution indicating the relationship between the second angle φ, each frequency of the sound wave, and the gain of the sound wave collected by the horn microphone 40 when the first angle θ is fixed. Also, the gain here relates to the magnitude of the sound signal.

[0077] As described above, the directivity generator 210 generates directivity. Next, the operation of the microphone device 10 used in the vehicle will be described.

[0078] The microphone device 10 is attached, for example, near the rearview mirror in the vehicle interior (not shown). The sound wave due to the voice of the vehicle driver propagates through the directivity generator 210 and reaches the horn microphone 40. The horn microphone 40 converts this sound into an analog signal. The analog wiring 45 outputs the analog signal from the horn microphone 40 to a call system (not shown) outside the microphone device 10. At this time, since digital signal processing or the like is not performed, the latency is relatively small. Therefore, for example, the microphone device 10 is used as a hands-free call microphone between the call system.

[0079] In addition, sound waves caused by the sound inside the vehicle cabin propagate through the directivity generator 210 and reach the horn microphone 40. The horn microphone 40 converts this sound into an analog signal. The analog wiring 45 outputs the analog signal from the horn microphone 40 to the communication system. At this time, since digital signal processing or the like is not performed, the latency is relatively small. Also, since the analog signal does not pass through a relatively complex circuit, the microphone device 10 becomes robust against disturbances such as being impacted. For this reason, for example, the microphone device 10 is used as an emergency call microphone for knowing the driver's state due to vehicle abnormalities, vehicle driver abnormalities, etc. between the communication system and the vehicle.

[0080] Furthermore, sound waves caused by the sound inside the vehicle cabin propagate through the opening 200 and the substrate hole 304 and reach the microphone 35. The microphone 35 converts this sound into an analog signal. Also, the ADC chip 50 converts the analog signal from this microphone 35 into a digital signal and converts the analog signal from the horn microphone 40 into a digital signal. Furthermore, the processing unit 60 performs sound source separation such as BSS on these converted digital signals using ICA, PCA, etc. Thereby, the processing unit 60 makes the noise included in the digital signal converted by the ADC chip 50 smaller than the noise included in the analog signal from the horn microphone 40. Also, the processing unit 60 outputs the signal after digital signal processing to an analysis system (not shown) outside the microphone device 10. The analysis system performs, for example, speech recognition on this signal after digital signal processing. Therefore, the microphone device 10 is used as a microphone for speech recognition between the analysis system and the vehicle.

[0081] As described above, the microphone device 10 operates. Next, an explanation will be given regarding the microphone device 10 performing digital signal processing while suppressing an increase in latency.

[0082] Here, in the acoustic system described in Patent Document 1, digital signal processing such as noise reduction may be performed on the electrical signal converted by the capsule. In this case, for example, AD conversion, buffering with the CPU, and DA conversion require a processing time of several tens of milliseconds. Also, when converting to the frequency domain and processing with the CPU, a processing time of 160 ms is required. Therefore, the latency, which is the communication delay time, increases.

[0083] Also, here, in a phone call, the average value of the latency is set to 150 ms. Furthermore, when the latency exceeds 200 ms, problems such as overlapping speech timings occur. Thus, when the latency increases, the call becomes difficult, and the call quality deteriorates. For this reason, it is difficult to use for hands-free calls and the above-mentioned emergency calls.

[0084] Also, if digital signal processing is not performed, the call becomes difficult due to noise, so the call quality deteriorates. Furthermore, the accuracy of speech recognition decreases, making it difficult to use for speech recognition.

[0085] In contrast, the microphone device 10 of the present embodiment includes a housing 20, a microphone 35, a horn microphone 40, an analog wiring 45, an ADC chip 50, and a processing unit 60.

[0086] The housing 20 has an opening 200 and a first horn 211. The first horn 211 includes a first horn opening 231 and a first horn tube 241. The microphone 35 is housed in the housing 20 and converts the sound propagated through the opening 200 into an analog signal. The horn microphone 40 is housed in the housing 20 and converts the sound propagated through the first horn 211 into an analog signal. The analog wiring 45 is housed in the housing 20 and outputs the analog signal from the horn microphone 40.

[0087] The ADC chip 50 acquires the analog signal from the microphone 35 and also acquires the analog signal from the horn microphone 40 via the digital wiring 55. Further, the ADC chip 50 converts the analog signals from the microphone 35 and the horn microphone 40 into digital signals. Note that the digital wiring 55 corresponds to a wiring different from the analog wiring 45.

[0088] The processing unit 60 performs digital signal processing on the digital signals converted by the ADC chip 50. For example, the processing unit 60 performs sound source separation on the digital signals converted by the ADC chip 50. Thereby, the processing unit 60 makes the noise included in the digital signals converted by the ADC chip 50 smaller than the noise included in the analog signals from the horn microphone 40.

[0089] Since the signal output from the analog wiring 45 is not digitally signal - processed, it is a signal with suppressed increase in latency. Also, in the processing unit 60, digital signal processing is performed. Therefore, the microphone device 10 performs digital signal processing while suppressing an increase in latency. For this reason, the microphone device 10 can be used as any of the hands - free call microphone, the emergency call microphone, and the voice recognition microphone as described above.

[0090] Also, the microphone device 10 of the first embodiment has the following effects.

[0091] [1 - 1] The housing 20 has the first horn 211, the second horn 212, the third horn 213, and the fourth horn 214, and has a plurality of horns.

[0092] Thereby, it becomes easier to collect sound by the horn microphone 40. For this reason, it becomes easier to secure the SNR of the analog signal from the horn microphone 40. Note that SNR is an abbreviation for Signal Noise Ratio.

[0093] [1-2] The housing 20 has a first horn 211, a second horn 212, a third horn 213, a fourth horn 214, a first acoustic tube 221, a second acoustic tube 222, a third acoustic tube 223, and a fourth acoustic tube 224. Also, the horn microphone 40 converts the sound propagated through the first horn 211, the first acoustic tube 221, the third acoustic tube 223, and the fourth acoustic tube 224 into an analog signal. Further, the horn microphone 40 converts the sound propagated through the second horn 212, the first acoustic tube 221, the third acoustic tube 223, and the fourth acoustic tube 224 into an analog signal. Also, the horn microphone 40 converts the sound propagated through the third horn 213, the second acoustic tube 222, the third acoustic tube 223, and the fourth acoustic tube 224 into an analog signal. Further, the horn microphone 40 converts the sound propagated through the fourth horn 214, the second acoustic tube 222, the third acoustic tube 223, and the fourth acoustic tube 224 into an analog signal.

[0094] Directivity is generated by the first horn 211, the second horn 212, the third horn 213, the fourth horn 214, the first acoustic tube 221, the second acoustic tube 222, the third acoustic tube 223, and the fourth acoustic tube 224. Also, as described above, the directivity on the YZ plane is generated by a1 and a2. Therefore, it is easy to control the directivity on the YZ plane. Further, also, the directivity on the XZ plane is generated by b1 and b2. Therefore, it is easy to control the directivity on the XZ plane.

[0095] [1-3] Here, assume that the first horn 211, the second horn 212, and the first acoustic tube 221 are uniform cylindrical shapes and have the same cross-sectional area. In this case, when sound waves from the outside of the microphone device 10 reach the first horn 211 and the second horn 212, since the acoustic impedance changes rapidly, they are easily reflected at the first horn opening 231 and the second horn opening 232. Therefore, in this case, sound waves from the outside of the microphone device 10 are difficult to enter the first horn 211 and the second horn 212.

[0096] Also, in this case, part of the sound propagating from the first horn 211 through the first acoustic tube 221 is propagated to the second horn 212. Since the acoustic impedance changes abruptly for the sound wave propagated to the second horn 212, it is reflected at the second horn opening 232. Part of the sound wave reflected at the second horn opening 232 propagates through the second horn 212 and the first acoustic tube 221 and is propagated to the first horn 211. Since the acoustic impedance changes abruptly for the sound wave propagated to the first horn 211, it is reflected at the first horn opening 231. Part of the sound wave reflected at the first horn opening 231 propagates through the first horn 211, the first acoustic tube 221, and the second horn 212 and is reflected at the second horn opening 232. Such sound waves reciprocating between the first horn 211 and the second horn 212 become reverberation. This reverberant sound makes speech recognition difficult.

[0097] Furthermore, here, assume that the lengths of the first horn 211, the second horn 212, and the first acoustic tube 221 are lengths related to an integral multiple of the half wavelength of the sound wave. At this time, the sound waves reciprocating between the first horn 211 and the second horn 212 resonate. This resonant sound degrades the frequency characteristics of the microphone device 10 and makes speech recognition difficult.

[0098] Also, assume that the third horn 213, the fourth horn 214, and the second acoustic tube 222 are of uniform cylindrical shape and have the same cross-sectional area. In this case, similar to the above, sound waves from outside the microphone device 10 are difficult to enter the third horn 213 and the fourth horn 214. Furthermore, the sound waves reciprocating between the third horn 213 and the fourth horn 214 become reverberation. This reverberant sound makes speech recognition difficult. Also, assume that the lengths of the third horn 213, the fourth horn 214, and the second acoustic tube 222 are lengths related to an integral multiple of the half wavelength of the sound wave. At this time, similar to the above, the sound waves reciprocating between the third horn 213 and the fourth horn 214 resonate. This resonant sound degrades the frequency characteristics of the microphone device 10 and makes speech recognition difficult.

[0099] On the other hand, the cross-sectional area of the first horn tube 241 when cut in a direction orthogonal to one direction increases as it goes from the side of the first horn tube 241 opposite to the first horn opening 231 toward the first horn opening 231 side. Here, the cross-sectional area of the first horn tube 241 when cut in a direction orthogonal to the Z axis increases as it goes in the positive direction of the Z axis. Further, the cross-sectional areas of the second horn tube 242, the third horn tube 243, and the fourth horn tube 244 increase as they go in the positive direction of the Z axis, similar to the cross-sectional area of the first horn tube 241.

[0100] As a result, changes in the acoustic impedance at the first horn opening 231, the second horn opening 232, the third horn opening 233, and the fourth horn opening 234 are suppressed. For this reason, sound waves from outside the microphone device 10 are less likely to be reflected at the first horn opening 231, the second horn opening 232, the third horn opening 233, and the fourth horn opening 234. For this reason, sound waves from outside the microphone device 10 are more likely to enter the first horn 211, the second horn 212, the third horn 213, and the fourth horn 214.

[0101] In addition, sound waves that propagate from the first horn 211 through the first acoustic tube 221 and are propagated to the second horn 212 are less likely to be reflected at the second horn opening 232. Furthermore, sound waves that propagate from the second horn 212 through the first acoustic tube 221 and are propagated to the first horn 211 are less likely to be reflected at the first horn opening 231. Therefore, sound waves that reciprocate between the first horn 211 and the second horn 212 are less likely to be generated, so reverberation is less likely to occur. Similarly, sound waves that propagate from the third horn 213 through the second acoustic tube 222 and are propagated to the fourth horn 214 are less likely to be reflected at the fourth horn opening 234. Furthermore, sound waves that propagate from the fourth horn 214 through the second acoustic tube 222 and are propagated to the third horn 213 are less likely to be reflected at the third horn opening 233. Thus, sound waves that reciprocate between the third horn 213 and the fourth horn 214 are less likely to be generated, so reverberation is less likely to occur. Therefore, voice recognition becomes easier.

[0102] Furthermore, since the first horn 211 and the second horn 212 do not have a uniform cross-sectional area, it becomes difficult for the sound waves reciprocating in the first horn 211 and the second horn 212 to resonate. Also, since the third horn 213 and the fourth horn 214 do not have a uniform cross-sectional area, it becomes difficult for the sound waves reciprocating in the third horn 213 and the fourth horn 214 to resonate. For these reasons, the deterioration of the frequency characteristics of the microphone device 10 is suppressed, and voice recognition becomes easier.

[0103] (Second Embodiment) In the second embodiment, as shown in FIGS. 17, 18, and 19, the form of the housing 20 is different from that of the first embodiment. Other than this, it is the same as the first embodiment.

[0104] The housing 20 further includes a first layer 251, a second layer 252, a third layer 253, and a fourth layer 254. The second layer 252 is connected to the first layer 251 in one direction, here, the Z-axis direction. The third layer 253 is connected to the side of the second layer 252 opposite to the first layer 251. The fourth layer 254 is connected to the side of the third layer 253 opposite to the second layer 252.

[0105] Also, the first horn 211, the second horn 212, the third horn 213, and the fourth horn 214 are formed in the first layer 251. Furthermore, as shown in FIG. 19, the first layer 251 covers the substrate 30, the microphone 35, the ADC chip 50, and the processing unit 60.

[0106] Returning to FIGS. 17 and 18, the first acoustic tube 221 and the second acoustic tube 222 are formed in the second layer 252. Also, the third acoustic tube 223 is formed in the third layer 253. Furthermore, the fourth acoustic tube 224 is formed in the fourth layer 254, and the horn microphone 40 and the analog wiring 45 are accommodated.

[0107] As described above, the microphone device 10 of the second embodiment is configured. Also in this second embodiment, the same effects as those of the first embodiment are achieved. Further, the second embodiment has the effects described below.

[0108] [2] The housing 20 further includes a first layer 251, a second layer 252, a third layer 253, and a fourth layer 254.

[0109] Thus, even if the entire housing 20 has a complex shape, the housing 20 can be divided into a simple shape and manufactured using injection molding or the like. Therefore, since the housing 20 is easier to manufacture, the microphone device 10 is easier to manufacture.

[0110] (Third Embodiment) In the third embodiment, as shown in FIG. 20, the form of the housing 20 is different from that of the second embodiment. Specifically, the housing 20 further includes a first guide portion 261 and a second guide portion 262. Other than this, it is the same as the second embodiment.

[0111] The first guide portion 261 restricts the third layer 253 from relatively moving only in the Y-axis direction, which is a direction orthogonal to one direction and the direction in which the first acoustic tube 221 extends, with respect to the second layer 252. For example, the first guide portion 261 includes a first concave portion 2611 and a first convex portion 2612.

[0112] The first concave portion 2611 is recessed from the inside of the surface of the second layer 252 that faces the third layer 253 and extends in the Y-axis direction. Further, a plurality of first concave portions 2611 are formed, and here, the number of first concave portions 2611 is two. Furthermore, the first concave portion 2611 is formed in a triangular prism shape. Thereby, stress concentration is less likely to occur, and the second layer 252 is less likely to be damaged. Also, the first concave portion 2611 is formed so as not to straddle the third acoustic tube 223. Note that the number of first concave portions 2611 is not limited to two, and at least one is sufficient. Furthermore, the shape of the first concave portion 2611 is not limited to a triangular prism shape. The shape of the first concave portion 2611 may be a polygonal prism shape, an arc-shaped prism shape, or the like.

[0113] The first convex portion 2612 protrudes from the interior of the surface of the third layer 253 facing the second layer 252 toward the second layer 252. Also, the first convex portion 2612 is formed in a shape corresponding to the first concave portion 2611. Further, the first convex portion 2612 moves within the first concave portion 2611. Thereby, the first guide portion 261 relatively moves the third layer 253 with respect to the second layer 252 only in the Y-axis direction. Here, the first concave portion 2611 is formed in the second layer 252 and the first convex portion 2612 is formed in the third layer 253, but it is not limited thereto. Any form that can relatively move only in the Y-axis direction is acceptable. The first convex portion 2612 may be formed in the second layer 252 and the first concave portion 2611 may be formed in the third layer 253.

[0114] The second guide portion 262 restricts the third layer 253 so that it can relatively move with respect to the fourth layer 254 only in a direction orthogonal to one direction and in the direction in which the third acoustic tube 223 extends, here, only in the X-axis direction. For example, the second guide portion 262 includes a second concave portion 2621 and a second convex portion 2622.

[0115] The second concave portion 2621 is recessed from the interior of the surface of the third layer 253 facing the fourth layer 254 and extends in the X-axis direction. Also, a plurality of second concave portions 2621 are formed, and here, the number of the second concave portions 2621 is two. Further, the second concave portion 2621 is formed in a triangular prism shape. Thereby, stress concentration is less likely to occur and the third layer 253 is less likely to be damaged. Also, the second concave portion 2621 is formed so as not to straddle the third acoustic tube 223. Note that the number of the second concave portions 2621 is not limited to two, and at least one is acceptable. Further, the shape of the second concave portion 2621 is not limited to a triangular prism shape. The shape of the second concave portion 2621 may be a polygonal prism shape, an arc prism shape, or the like.

[0116] The second convex portion 2622 protrudes from the inside of the surface of the fourth layer 254 facing the third layer 253 toward the third layer 253. Further, the second convex portion 2622 is formed in a shape corresponding to the second concave portion 2621. Furthermore, the second convex portion 2622 moves within the second concave portion 2621. Thereby, the second guide portion 262 relatively moves the third layer 253 with respect to the fourth layer 254 only in the X-axis direction. Here, the second concave portion 2621 is formed in the third layer 253 and the second convex portion 2622 is formed in the fourth layer 254, but the present invention is not limited thereto. Any form that allows relative movement only in the X-axis direction is acceptable. The second convex portion 2622 may be formed in the third layer 253 and the second concave portion 2621 may be formed in the fourth layer 254.

[0117] As described above, the microphone device 10 of the third embodiment is configured. Also in this third embodiment, the same effects as those of the second embodiment are achieved. Further, in the third embodiment, the following effects are also achieved.

[0118] [3-1] The housing 20 has a first guide portion 261. The first guide portion 261 relatively moves the third layer 253 with respect to the second layer 252 in a direction orthogonal to one direction and in the direction in which the first acoustic tube 221 extends, which is the Y-axis direction here.

[0119] Thereby, it becomes easier to adjust the positions of the first acoustic tube 221 and the second acoustic tube 222 formed in the second layer 252 and the third acoustic tube 223 formed in the third layer 253. For this reason, it becomes easier to adjust a1 and a2. Therefore, it becomes easier to control the directivity on the YZ plane generated by a1 and a2.

[0120] [3-2] The housing 20 has a second guide portion 262. The second guide portion 262 relatively moves the third layer 253 with respect to the fourth layer 254 in a direction orthogonal to one direction and in the direction in which the third acoustic tube 223 extends, which is the X-axis direction here.

[0121] This facilitates the position adjustment between the third acoustic tube 223 formed in the third layer 253 and the fourth acoustic tube 224 formed in the fourth layer 254. Therefore, it becomes easier to adjust b1 and b2. Thus, it becomes easier to control the directivity on the XZ plane generated by b1 and b2.

[0122] (Fourth Embodiment) In the fourth embodiment, as shown in FIG. 21, the forms of the first concave portion 2611, the first convex portion 2612, the second concave portion 2621, and the second convex portion 2622 are different from those in the third embodiment. Other than this, it is the same as the third embodiment.

[0123] The first concave portion 2611 is recessed from both corner portions on both sides in the direction parallel to the X-axis of the surface of the second layer 252 facing the third layer 253, instead of inside the surface of the second layer 252 facing the third layer 253. As a result, the vicinity of the first concave portion 2611 in the second layer 252 has a stepped shape. Further, the first concave portion 2611 extends in the Y-axis direction. Note that the first concave portion 2611 is not limited to being formed on both sides in the direction parallel to the X-axis, and may be formed on only one of either side in the direction parallel to the X-axis.

[0124] The first convex portion 2612 protrudes from the corner portion on the X-axis direction side of the surface of the third layer 253 facing the second layer 252, instead of inside the surface of the third layer 253 facing the second layer 252, toward the second layer 252. For this reason, the vicinity of the first convex portion 2612 in the third layer 253 has a stepped shape. Furthermore, the first convex portion 2612 is formed in a shape corresponding to the first concave portion 2611 and moves within the first concave portion 2611. Thereby, the first guide portion 261 relatively moves the third layer 253 in the Y-axis direction with respect to the second layer 252.

[0125] The second recess 2621 is recessed from the corner portions on both sides in the direction parallel to the Y-axis of the surface of the third layer 253 facing the fourth layer 254, instead of inside the surface of the third layer 253 facing the fourth layer 254. As a result, the vicinity of the second recess 2621 in the third layer 253 is stepped. Further, the second recess 2621 extends in the X-axis direction. Note that the second recess 2621 is not limited to being formed on both sides in the direction parallel to the Y-axis, and may be formed on only one of either side in the direction parallel to the Y-axis.

[0126] The second protrusion 2622 protrudes from the corner portion on the Y-axis direction side of the surface of the fourth layer 254 facing the third layer 253, instead of inside the surface of the fourth layer 254 facing the third layer 253, toward the third layer 253. For this reason, the vicinity of the second protrusion 2622 in the fourth layer 254 is stepped. Further, the second protrusion 2622 is formed in a shape corresponding to the second recess 2621 and moves within the second recess 2621. Thereby, the second guide portion 262 relatively moves the third layer 253 in the X-axis direction with respect to the fourth layer 254.

[0127] As described above, the microphone device 10 of the fourth embodiment is configured. Also in this fourth embodiment, the same effects as those of the third embodiment are achieved.

[0128] (Fifth Embodiment) In the fifth embodiment, as shown in FIGS. 22 and 23, the form of the directivity generator 210 is different from that of the first embodiment. Further, the microphone device 10 includes two horn microphones 40. Other than these, it is the same as the first embodiment.

[0129] The directivity generator 210 further has a fifth acoustic tube 225 in addition to the first horn 211, the second horn 212, the third horn 213, the fourth horn 214, the first acoustic tube 221, the second acoustic tube 222, the third acoustic tube 223, and the fourth acoustic tube 224.

[0130] The fifth acoustic tube 225 is formed in a cylindrical shape and is connected in the Z-axis direction between the first acoustic tube 221 and the second acoustic tube 222 in the third acoustic tube 223. Also, the fifth acoustic tube 225 extends in a direction intersecting the direction in which the third acoustic tube 223 extends. Here, it extends in the negative Z-axis direction from the third acoustic tube 223. Note that the fifth acoustic tube 225 is not limited to extending in the Z-axis direction from the third acoustic tube 223 and may extend in the Y-axis direction or the like from the third acoustic tube 223.

[0131] Also, the fourth acoustic tube 224 is connected to the first acoustic tube 221 side in the third acoustic tube 223. Further, the fifth acoustic tube 225 is connected to the second acoustic tube 222 side in the third acoustic tube 223. Therefore, the fourth acoustic tube 224 and the fifth acoustic tube 225 are arranged side by side in the direction in which the third acoustic tube 223 extends. Here, it is the X-axis direction.

[0132] Also, the microphone device 10 includes two horn microphones 40. Here, one of the horn microphones 40 is referred to as the first horn microphone 401, and the other horn microphone 40 is referred to as the second horn microphone 402.

[0133] The first horn microphone 401 is connected to the fourth acoustic tube 224. Also, the first horn microphone 401 converts the sound propagated through the first horn 211, the first acoustic tube 221, the third acoustic tube 223, and the fourth acoustic tube 224 into an analog signal. Further, the first horn microphone 401 converts the sound propagated through the second horn 212, the first acoustic tube 221, the third acoustic tube 223, and the fourth acoustic tube 224 into an analog signal. Also, the first horn microphone 401 converts the sound propagated through the third horn 213, the second acoustic tube 222, the third acoustic tube 223, and the fourth acoustic tube 224 into an analog signal. Further, the first horn microphone 401 converts the sound propagated through the fourth horn 214, the second acoustic tube 222, the third acoustic tube 223, and the fourth acoustic tube 224 into an analog signal. Also, the first horn microphone 401 outputs the converted analog signal to the outside of the microphone device 10 via the analog wiring 45. Further, the first horn microphone 401 outputs the converted analog signal to the ADC chip 50 via the digital wiring 55 and the substrate 30.

[0134] The second horn microphone 402 is connected to the fifth acoustic tube 225. Also, the second horn microphone 402 converts the sound propagated through the first horn 211, the first acoustic tube 221, the third acoustic tube 223, and the fifth acoustic tube 225 into an analog signal. Further, the second horn microphone 402 converts the sound propagated through the second horn 212, the first acoustic tube 221, the third acoustic tube 223, and the fifth acoustic tube 225 into an analog signal. Also, the second horn microphone 402 converts the sound propagated through the third horn 213, the second acoustic tube 222, the third acoustic tube 223, and the fifth acoustic tube 225 into an analog signal. Further, the second horn microphone 402 converts the sound propagated through the fourth horn 214, the second acoustic tube 222, the third acoustic tube 223, and the fifth acoustic tube 225 into an analog signal. Also, the second horn microphone 402 outputs the converted analog signal to the ADC chip 50 via the digital wiring 55 and the substrate 30. Here, the second horn microphone 402 does not output the converted analog signal to the outside of the microphone device 10 via the analog wiring 45. On the other hand, the second horn microphone 402 may output the converted analog signal to the outside of the microphone device 10 via wiring or the like.

[0135] As described above, the microphone device 10 of the fifth embodiment is configured. Also in this fifth embodiment, the same effects as those of the first embodiment are achieved. Further, in the fifth embodiment, the following effects are also achieved.

[0136] [4] The housing 20 further has the fifth acoustic tube 225. Also, the microphone device 10 includes the first horn microphone 401 and the second horn microphone 402.

[0137] As a result, similar to the directivity on the XZ plane defined by b1 and b2 in the first embodiment, the directivity on the XZ plane can be independently determined in two ways depending on the positions where the fourth acoustic tube 224 and the fifth acoustic tube 225 are arranged in the third acoustic tube 223. For this reason, for example, when the microphone device 10 is used in a vehicle, the first horn microphone 401 can collect the voice of the vehicle driver and the like, while the second horn microphone 402 can collect the voice of passengers other than the vehicle driver and the like.

[0138] (Other embodiments) The present disclosure is not limited to the above embodiments, and appropriate modifications can be made to the above embodiments. Also, in each of the above embodiments, it goes without saying that the elements constituting the embodiments are not necessarily essential except in cases where it is explicitly stated that they are essential or in cases where they are considered to be clearly essential in principle.

[0139] The conversion unit, processing unit, and their methods described in the present disclosure may be realized by a dedicated computer provided by configuring a processor and a memory programmed to execute one or more functions embodied by a computer program. Alternatively, the conversion unit, processing unit, and their methods described in the present disclosure may be realized by a dedicated computer provided by configuring a processor with one or more dedicated hardware logic circuits. Or, the conversion unit, processing unit, and their methods described in the present disclosure may be realized by one or more dedicated computers configured by a combination of a processor and a memory programmed to execute one or more functions and a processor configured by one or more hardware logic circuits. Also, the computer program may be stored in a computer-readable non-transitory tangible recording medium as instructions to be executed by a computer.

[0140] In each of the above embodiments, the number of the openings 200, microphones 35, and converters 500 is six. In contrast, the number of the openings 200, microphones 35, and converters 500 is not limited to six and may be at least one.

[0141] In each of the above embodiments, four horns are formed. In contrast, the number of horns is not limited to four and may be at least one. Further, in each of the above embodiments, the horn microphone 40 is connected to each horn via the first acoustic tube 221, the second acoustic tube 222, the third acoustic tube 223, and the fourth acoustic tube 224. In contrast, the horn microphone 40 may be directly connected to each horn without passing through the first acoustic tube 221, the second acoustic tube 222, the third acoustic tube 223, and the fourth acoustic tube 224.

[0142] In each of the above embodiments, the substrate 30, the ADC chip 50, and the processing unit 60 are housed in the housing 20. In contrast, the substrate 30, the ADC chip 50, and the processing unit 60 are not limited to being housed in the housing 20. The substrate 30, the ADC chip 50, and the processing unit 60 may be arranged outside the housing 20.

[0143] In each of the above embodiments, the ADC chip 50 is mounted on the substrate surface 300. In contrast, the ADC chip 50 is not limited to being mounted on the substrate surface 300 and may be mounted on the back surface 302 of the substrate. Further, the ADC chip 50 may be mounted on a printed circuit board different from the substrate 30 arranged in the housing 20.

[0144] In each of the above embodiments, the processing unit 60 is mounted on the back surface 302 of the substrate. In contrast, the processing unit 60 is not limited to being mounted on the back surface 302 of the substrate and may be mounted on the substrate surface 300. Further, the processing unit 60 may be mounted on a printed circuit board different from the substrate 30 arranged in the housing 20.

[0145] In the above-described first to fifth embodiments, the number of the fourth acoustic tubes 224 is one. Further, in the above-described fifth embodiment, the number of the fifth acoustic tubes 225 is one. In contrast, the number of the fourth acoustic tubes 224 and the fifth acoustic tubes 225 is not limited to one, and two or more may be provided.

[0146] (Viewpoint of the present disclosure) [Viewpoint 1] A housing (20) having an open opening (200), a horn (211) formed at a position different from the opening and having an open horn opening (231) and a horn tube (241) connected to the horn opening and extending in one direction, A microphone (35) housed in the housing and converting the sound propagated through the opening into an analog signal, A horn microphone (40) housed in the housing and converting the sound propagated through the horn into an analog signal, An analog wiring (45) housed in the housing and outputting an analog signal from the horn microphone, A conversion unit (50) that acquires the analog signal from the microphone and acquires the analog signal from the horn microphone via a wiring (55) different from the analog wiring, and converts the analog signals from the microphone and the horn microphone into digital signals, A processing unit (60) that performs digital signal processing on the digital signal converted by the conversion unit, A microphone device comprising: [Viewpoint 2] The housing is the microphone device according to Viewpoint 1 having a plurality of the horns. [Viewpoint 3] The horn opening is a first horn opening, The horn tube is a first horn tube, The horn is a first horn, The housing is A second horn (212), A third horn (213), a fourth horn (214), a first acoustic tube (221), a second acoustic tube (222), a third acoustic tube (223), a fourth acoustic tube (224), and further includes the second horn includes a second horn opening (232) and a second horn tube (242), the second horn opening is formed at a position different from the opening and the first horn opening, and opens in the direction in which the first horn opening opens, the second horn tube is connected to the second horn opening and extends in the one direction, the third horn includes a third horn opening (233) and a third horn tube (243), the third horn opening is formed at a position different from the opening, the first horn opening and the second horn opening, and opens in the direction in which the first horn opening opens, the third horn tube is connected to the third horn opening and extends in the one direction, the fourth horn includes a fourth horn opening (234) and a fourth horn tube (244), the fourth horn opening is formed at a position different from the opening, the first horn opening, the second horn opening and the third horn opening, and opens in the direction in which the first horn opening opens, the fourth horn tube is connected to the fourth horn opening and extends in the one direction, the first horn and the second horn are arranged side by side in a direction orthogonal to the one direction, the first horn and the third horn are arranged side by side in a direction orthogonal to the one direction and the direction in which the first horn and the second horn are arranged, the second horn and the fourth horn are arranged side by side in a direction orthogonal to the one direction and the direction in which the first horn and the second horn are arranged, The third horn and the fourth horn are arranged in the direction in which the first horn and the second horn are arranged. The first acoustic tube is connected to the first horn tube and the second horn tube, and extends in a direction intersecting the one direction. The second acoustic tube is connected to the third horn tube and the fourth horn tube, and extends in the direction in which the first acoustic tube extends. The third acoustic tube is connected to the first acoustic tube and the second acoustic tube, and extends in a direction intersecting the one direction and the direction in which the first acoustic tube extends. The fourth acoustic tube is connected to the portion between the first acoustic tube and the second acoustic tube of the third acoustic tube, and extends in a direction intersecting the direction in which the third acoustic tube extends. The horn microphone The sound propagated through the first horn, the first acoustic tube, the third acoustic tube, and the fourth acoustic tube, The sound propagated through the second horn, the first acoustic tube, the third acoustic tube, and the fourth acoustic tube, The sound propagated through the third horn, the second acoustic tube, the third acoustic tube, and the fourth acoustic tube, The sound propagated through the fourth horn, the second acoustic tube, the third acoustic tube, and the fourth acoustic tube, The microphone device according to Aspect 1 that converts the above into an analog signal. [Aspect 4] The housing has a first layer (251), a second layer (252) connected to the first layer in the one direction, a third layer (253) connected to the side of the second layer opposite to the first layer, a fourth layer (254) connected to the side of the third layer opposite to the second layer, and further has The first layer is formed with the first horn, the second horn, the third horn, and the fourth horn. The second layer is formed with the first acoustic tube and the second acoustic tube. In the third layer, the third acoustic tube is formed. The microphone device according to viewpoint 3, wherein the fourth acoustic tube is formed in the fourth layer. [Viewpoint 5] The microphone device according to viewpoint 4, wherein the horn microphone is housed in the fourth layer. [Viewpoint 6] The microphone device according to viewpoint 4 or 5, wherein the housing has a guide portion (261) that relatively moves the third layer with respect to the second layer in a direction orthogonal to the one direction and in the direction in which the first acoustic tube extends. [Viewpoint 7] The microphone device according to viewpoint 4 or 5, wherein the housing has a guide portion (262) that relatively moves the third layer with respect to the fourth layer in a direction orthogonal to the one direction and in the direction in which the third acoustic tube extends. [Viewpoint 8] The housing has a fifth acoustic tube (225) that is connected between the first acoustic tube and the second acoustic tube among the third acoustic tubes and extends in a direction intersecting the direction in which the third acoustic tube extends. The fourth acoustic tube is connected to the first acoustic tube side among the third acoustic tubes. The fifth acoustic tube is connected to the second acoustic tube side among the third acoustic tubes. The fourth acoustic tube and the fifth acoustic tube are arranged side by side in the direction in which the third acoustic tube extends. The horn microphone is a first horn microphone. The microphone device further includes a second horn microphone (402). The first horn microphone and the second horn microphone are arranged side by side in the direction in which the third acoustic tube extends. The first horn microphone is the sound propagated through the first horn, the first acoustic tube, the third acoustic tube, and the fourth acoustic tube, the sound propagated through the second horn, the first acoustic tube, the third acoustic tube, and the fourth acoustic tube, The sound propagated through the third horn, the second acoustic tube, the third acoustic tube, and the fourth acoustic tube, and The sound propagated through the fourth horn, the second acoustic tube, the third acoustic tube, and the fourth acoustic tube, and are converted into analog signals, The second horn microphone The sound propagated through the first horn, the first acoustic tube, the third acoustic tube, and the fifth acoustic tube, and The sound propagated through the second horn, the first acoustic tube, the third acoustic tube, and the fifth acoustic tube, and The sound propagated through the third horn, the second acoustic tube, the third acoustic tube, and the fifth acoustic tube, and The sound propagated through the fourth horn, the second acoustic tube, the third acoustic tube, and the fifth acoustic tube, and The microphone device according to any one of aspects 3 to 7 for converting into an analog signal. [Aspect 9] The cross-sectional area of the horn tube when cut in a direction orthogonal to the one direction is increasing as it goes from the side opposite to the horn opening to the horn opening side in the horn tube. The microphone device according to any one of aspects 1 to 8. [Aspect 10] The processing unit performs sound source separation on the digital signal converted by the conversion unit, so that the noise included in the digital signal converted by the conversion unit is smaller than the noise included in the analog signal from the horn microphone. The microphone device according to any one of aspects 1 to 9.

Description of Symbols

[0147] 10 Microphone device 20 Housing 200 Opening 211 First horn 35 Microphone 40 Horn microphone 45 Analog wiring 55 Digital wiring 50 ADC chip 60 Processing Unit

Claims

1. A housing (20) having an open opening (200), a horn (211) formed at a position different from the opening and having an open horn opening (231) and a horn tube (241) connected to the horn opening and extending in one direction, A microphone (35) housed in the housing and converting sound propagated through the opening into an analog signal, A horn microphone (40) housed in the housing and converting sound propagated through the horn into an analog signal, An analog wiring (45) housed in the housing and outputting an analog signal from the horn microphone, A conversion unit (50) that acquires an analog signal from the microphone, acquires an analog signal from the horn microphone via a wiring (55) different from the analog wiring, and converts the analog signals from the microphone and the horn microphone into digital signals, A processing unit (60) that performs digital signal processing on the digital signal converted by the conversion unit, A microphone device comprising the above.

2. The microphone device according to claim 1, wherein the housing has a plurality of the horns.

3. The horn opening is a first horn opening, The horn tube is a first horn tube, The horn is a first horn, The housing, A second horn (212), A third horn (213), A fourth horn (214), A first acoustic tube (221), A second acoustic tube (222), A third acoustic tube (223), A fourth acoustic tube (224), Further having the above, The second horn includes a second horn opening (232) and a second horn tube (242), The second horn opening is formed at a position different from the opening and the first horn opening, and opens in the direction in which the first horn opening opens, The second horn tube is connected to the second horn opening and extends in the one direction, The third horn includes a third horn opening (233) and a third horn tube (243), The third horn opening is formed at a position different from the opening, the first horn opening, and the second horn opening, and opens in the direction in which the first horn opening opens, The third horn tube is connected to the third horn opening and extends in the one direction, The fourth horn includes a fourth horn opening (234) and a fourth horn tube (244), The fourth horn opening is formed at a position different from the opening, the first horn opening, the second horn opening, and the third horn opening, and opens in the direction in which the first horn opening opens, The fourth horn tube is connected to the fourth horn opening and extends in the one direction, The first horn and the second horn are arranged side by side in a direction orthogonal to the one direction, The first horn and the third horn are arranged side by side in a direction orthogonal to the one direction and the direction in which the first horn and the second horn are arranged, The second horn and the fourth horn are arranged side by side in a direction orthogonal to the one direction and the direction in which the first horn and the second horn are arranged, The third horn and the fourth horn are arranged side by side in the direction in which the first horn and the second horn are arranged, The first acoustic tube is connected to the first horn tube and the second horn tube and extends in a direction intersecting the one direction, The second acoustic tube is connected to the third horn tube and the fourth horn tube, and extends in the direction in which the first acoustic tube extends. The third acoustic tube is connected to the first acoustic tube and the second acoustic tube, and extends in a direction intersecting the one direction and the direction in which the first acoustic tube extends. The fourth acoustic tube is connected to a portion between the first acoustic tube and the second acoustic tube of the third acoustic tube, and extends in a direction intersecting the direction in which the third acoustic tube extends. The horn microphone The sound propagated through the first horn, the first acoustic tube, the third acoustic tube, and the fourth acoustic tube, The sound propagated through the second horn, the first acoustic tube, the third acoustic tube, and the fourth acoustic tube, The sound propagated through the third horn, the second acoustic tube, the third acoustic tube, and the fourth acoustic tube, The sound propagated through the fourth horn, the second acoustic tube, the third acoustic tube, and the fourth acoustic tube, The microphone device according to claim 1, which converts the above into an analog signal.

4. The housing A first layer (251), A second layer (252) connected to the first layer in the one direction, A third layer (253) connected to a side of the second layer opposite to the first layer, A fourth layer (254) connected to a side of the third layer opposite to the second layer, Further includes The first layer is formed with the first horn, the second horn, the third horn, and the fourth horn. The second layer is formed with the first acoustic tube and the second acoustic tube. The third layer is formed with the third acoustic tube. The microphone device according to claim 3, wherein the fourth layer is formed with the fourth acoustic tube.

5. The microphone device according to claim 4, wherein the horn microphone is accommodated in the fourth layer.

6. The microphone device according to claim 4, wherein the housing has a guide portion (261) that relatively moves the third layer with respect to the second layer in a direction orthogonal to the one direction and in a direction in which the first acoustic tube extends.

7. The microphone device according to claim 4, wherein the housing has a guide portion (262) that relatively moves the third layer with respect to the fourth layer in a direction orthogonal to the one direction and in a direction in which the third acoustic tube extends.

8. The housing has a fifth acoustic tube (225) that is connected between the first acoustic tube and the second acoustic tube among the third acoustic tubes and extends in a direction intersecting the direction in which the third acoustic tube extends. The fourth acoustic tube is connected to the first acoustic tube side among the third acoustic tubes. The fifth acoustic tube is connected to the second acoustic tube side among the third acoustic tubes. The fourth acoustic tube and the fifth acoustic tube are arranged side by side in the direction in which the third acoustic tube extends. The horn microphone is a first horn microphone. The microphone device further includes a second horn microphone (402). The first horn microphone and the second horn microphone are arranged side by side in the direction in which the third acoustic tube extends. The first horn microphone The sound propagated through the first horn, the first acoustic tube, the third acoustic tube, and the fourth acoustic tube, The sound propagated through the second horn, the first acoustic tube, the third acoustic tube, and the fourth acoustic tube, The sound propagated through the third horn, the second acoustic tube, the third acoustic tube, and the fourth acoustic tube, The sound propagated through the fourth horn, the second acoustic tube, the third acoustic tube, and the fourth acoustic tube, Convert it into an analog signal, The second horn microphone, The sound propagated through the first horn, the first acoustic tube, the third acoustic tube, and the fifth acoustic tube, The sound propagated through the second horn, the first acoustic tube, the third acoustic tube, and the fifth acoustic tube, The sound propagated through the third horn, the second acoustic tube, the third acoustic tube, and the fifth acoustic tube, The sound propagated through the fourth horn, the second acoustic tube, the third acoustic tube, and the fifth acoustic tube, The microphone device according to any one of claims 3 to 6, which converts the above into an analog signal.

9. The cross-sectional area of the horn tube when cut in a direction orthogonal to the one direction is increasing as it goes from the side opposite to the horn opening to the horn opening side in the horn tube. The microphone device according to any one of claims 1 to 3.

10. The processing unit performs sound source separation on the digital signal converted by the conversion unit, so that the noise included in the digital signal converted by the conversion unit is smaller than the noise included in the analog signal from the horn microphone. The microphone device according to any one of claims 1 to 3.

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