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JP2007104582

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DESCRIPTION JP2007104582
[PROBLEMS] To enable highly accurate and stable directional sound collection and stereo sound
collection with a small microphone device alone. SOLUTION: MEMS sound pickup elements 11a
and 11b manufactured using MEMS technology and having high accuracy and excellent stability
are arranged in parallel, mounted on a common mounting substrate 65, and housed in a capsule
64. The capsule 64 has a structure capable of preventing the leak of the diffracted sound. For
example, the capsule 90 is made to be a sound transmitting mesh structure. As a result, the
acoustic paths (P1, P2) are unified, and directional sound collection becomes possible by
appropriate arithmetic processing. [Selected figure] Figure 1
Microphone device
[0001]
The present invention relates to a microphone device, and more particularly to a microphone
device capable of directional sound collection (including stereo sound collection).
[0002]
A conventional example in which a pair of electret condenser microphones (ECMs) capable of
directional sound collection is mounted is described in Patent Document 1 (see FIG. 1 (b) of
Patent Document 1).
The structure of the conventional example described in FIG. 1 (b) of Patent Document 1 will be
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1
briefly described below with reference to FIG. FIG. 7 is a cross-sectional view showing a structure
of a conventional example (an example in which a pair of electret condenser microphones is
housed in a common capsule) described in FIG.
[0003]
As illustrated, the microphone device of Patent Document 1 is configured by arranging a pair of
acoustic transducers in a common capsule 84 in a symmetrical manner. The acoustic transducer
unit is formed of a diaphragm 76, a spacer 77, and a back pole 78. The acoustic transducer unit
performs acoustic-electrical signal conversion, and converts an acoustic signal input to an
electrical signal output via the impedance conversion circuit 82. Convert.
[0004]
In FIG. 7, reference numeral 75 is a diaphragm ring, reference numeral 79 is a sound hole,
reference numeral 80 is a back pole holder, reference numeral 81 is a conversion circuit
accommodating portion, and reference numeral 83 is a shielding plate. It is.
[0005]
In the microphone device of FIG. 7, an impedance conversion circuit 82 is mounted at the center
of the shielding plate 83, and further, a back electrode holder 80 and a conversion circuit
housing portion 81 are formed, a transducer portion is formed, and a capsule 84 is covered. It
manufactures through the mechanical assembly process of bending the lower end part of the
capsule 84 inside by the caulking method.
In addition, the sensitivity of an array microphone composed of a plurality of microphones
disposed at a predetermined position takes advantage of the fact that the acoustic path from the
sound source to each microphone is different, so that appropriate delay and addition /
subtraction can be made to the output of each microphone. It is known to have directivity when
applied (see, for example, Japanese Patent Application Laid-Open No. 7-131886).
[0006]
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For example, the sound coming from a predetermined direction is received by the first and
second sound collection elements, and the second sound collection element receives sound
delayed by Δt after the first sound collection element receives the sound. Assume the case. In
this case, when the output signal from the second sound collection element is delayed by Δt and
then added to the signal obtained from the first sound collection element, the same signals are
superimposed, but the sound from the other direction is Since the superimposing effect can not
be obtained with respect to {circle around (1)}, the sound receiving sensitivity is improved with
respect to the sound from the above-mentioned predetermined direction, and directional sound
receiving becomes possible.
[0007]
That is, the acoustic path from the sound source to each of the sound collection elements
constituting the array microphone is different, which is a premise for directivity formation.
However, there are a plurality of acoustic paths from one sound source to one sound collection
element Then (for example, there may be a plurality of acoustic paths due to the sound
diffraction phenomenon), it becomes impossible to properly set the delay amount and coefficient
for directivity formation, and it is impossible to form good directivity. Become.
[0008]
JP, 2000-165998, A JP, 7-131886, A
[0009]
However, in the conventional microphone device described in Patent Document 1, when
mechanically assembling the microphone using the caulking method, the diaphragm ring
(reference numeral 75) or the spine is crimped when the capsule (reference numeral 84) is
crimped. It is difficult to load evenly to the poles (reference numeral 78), and the tension of each
diaphragm 76 changes, so that the sensitivity of each transducer portion becomes difficult to be
uniform.
That is, the sensitivity of the plurality of sound collection elements (transducers) varies.
This point hinders the realization of the formation of high precision and stable directivity.
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[0010]
The present invention has been made in view of the above situation, and it is an object of the
present invention to realize high accuracy and stable directivity by using one microphone module
in which at least two sound pickup elements are accommodated in a capsule. .
[0011]
A microphone device according to the present invention performs predetermined arithmetic
processing based on first and second sound collection elements manufactured using a
semiconductor manufacturing process, and output signals of the first and second sound
collection elements. A signal processing unit, and a microphone capsule disposed so as to cover
the first and second sound collecting elements and the signal processing unit, and at least a part
of which constitutes a sound transmitting mesh structure; A part of the sound directed from the
two sound sources to the first sound collecting element is prevented from reaching the second
sound collecting element by diffraction, and the sound from the one sound source to the second
sound collecting element It is characterized in that a part is prevented from reaching the first
sound collection element by diffraction.
[0012]
Capacitive sound pickup elements (MEMS sound pickup elements) manufactured using
microfabrication technology (MEMS technology) of silicon LSIs have high processing accuracy
compared to sound pickup elements manufactured by mechanical component assembly. , The
accuracy of electro-acoustic conversion is high and stable.
By utilizing this advantage, at least two sound pickup elements manufactured using a
semiconductor manufacturing process are housed in a common microphone capsule to constitute
one microphone device (microphone module).
However, if there are a plurality of acoustic paths from the sound source to each sound collection
element due to the diffraction of sound, it becomes difficult to form directivity, so a capsule
(casing) of a structure that can prevent the generation of acoustic paths due to diffraction. It is
what to adopt. Thereby, it is possible to realize high accuracy and stable directivity by using one
microphone module in which at least two sound pickup elements are housed in a capsule.
[0013]
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Furthermore, the present invention is characterized in that, in the above microphone device, at
least a part of the microphone capsule has a sound transmitting mesh structure. The sound
originally travels in a straight line, and no diffraction phenomenon occurs unless there is an
obstruction in the path under a predetermined condition. Therefore, at least a part of the capsule
(in particular, a portion necessary for causing the sound to reach the vibrating membrane of each
sound collection element) has an acoustically transparent (acoustically transparent) mesh
structure (this mesh is The sound coming from the sound source goes straight as it is and
reaches each sound collection element as it has a structure having a large number of holes with a
diameter that does not cause adverse effects due to diffraction. The sound from the sound source
travels straight and reaches each sound pickup element without being blocked by the casing
(capsule) of the microphone device. That is, the acoustic path leading to one sound collection
element is uniquely determined without causing an adverse effect due to acoustic diffraction.
Therefore, it becomes possible to appropriately set the delay amount and coefficient setting for
directivity formation, and it becomes possible to form good directivity.
[0014]
In the microphone device according to the present invention, the sound transmitting mesh
structure may be made of a conductive material. Since the mesh portion forms a part of the
casing (capsule), it is desirable not only to guide the sound from the sound source to the sound
collection element but also to have a shielding effect of electromagnetic wave noise. Therefore, a
mesh is formed of a conductive material (metal) to obtain an electromagnetic shielding effect.
[0015]
Further, according to the present invention, in the above-mentioned microphone device, the
signal processing unit performs delay processing and addition / subtraction processing on output
signals of the first and second sound collection elements, thereby realizing directional sound
collection. Including things. According to the above configuration, the signal processing unit for
performing the signal processing necessary for directional sound collection (including stereo
sound collection) is also accommodated in the casing (capsule). As a result, it is possible to obtain
a one-module microphone device capable of highly accurate and stable directional sound
collection (including stereo sound collection).
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[0016]
Further, according to the present invention, in the microphone device, the first and second sound
collecting elements and the signal processing unit are mounted on a common substrate.
According to the above configuration, the sound pickup element and the signal processing unit
are mounted on the common substrate, and the capsule is covered on the substrate to form one
module. For example, the signal processing unit is formed into an LSI, and the LSI is mounted
between a pair of adjacent sound collection elements, and the LSI and each of the sound
collection elements on both sides are connected by bonding wires or the like to achieve electrical
continuity. Can reduce wasted space, and a very compact module (a microphone device) having a
directional sound pickup function can be obtained.
[0017]
The present invention also includes the microphone device in which the first and second sound
collection elements and the signal processing unit are integrated in the same substrate.
According to the above configuration, the sound pickup element and the signal processing unit
are integrated and formed in the same substrate, and the capsule is covered on the substrate to
form one module. Desirably, the first and second sound collection elements and the signal
processing unit are integrated into an LSI, and the LSI is covered with a microcapsule having an
opening formed by a MEMS process, and is very compact A module (microphone device) having a
directional sound pickup function can be obtained.
[0018]
The present invention also includes the microphone device, wherein the microphone capsule is
formed by processing a substrate by a MEMS process. According to the above configuration,
further downsizing and thinning can be achieved.
[0019]
According to the present invention, the MEMS sound pickup elements having high accuracy and
excellent stability manufactured by using the MEMS technology are accommodated in the
capsule in a state of being arranged in parallel, and the capsule is leaked of the diffraction sound.
By using a compact microphone module in which at least two sound pickup elements are housed
in a capsule, by unifying the acoustic path as a structure that prevents air flow (a structure
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having a partition that airtightly separates each sound pickup element) It becomes possible to
easily realize high precision and stable directivity.
[0020]
That is, due to the mesh structure provided in the capsule, the sound that has passed through the
sound hole for one of the sound collection elements is prevented from coming around to the
other sound collection element by diffraction, reaching one acoustic path Can be
Therefore, it becomes possible to appropriately set the delay amount and coefficient setting for
directivity formation, and it becomes possible to form good directivity.
[0021]
Also, by accommodating the signal processing unit in the capsule, it is possible to obtain a onemodule microphone device capable of highly accurate and stable directional sound collection
(including stereo sound collection). Moreover, the shielding effect of electromagnetic wave noise
can be obtained by using a conductive mesh.
[0022]
Also, by mounting the sound pickup element and the signal processing unit on a common
substrate and covering the capsule on the substrate to form one module, a compact one-module
microphone device can be obtained. For example, the signal processing unit is formed into an LSI,
and the LSI is mounted between a pair of adjacent sound collection elements, and the LSI and
each of the sound collection elements on both sides are connected by bonding wires or the like to
achieve electrical continuity. Thus, a space can be reduced and a very compact microphone
device with a directional sound pickup function is realized.
[0023]
According to the present invention, it is possible to provide a microphone device having an effect
that directional sound collection and stereo sound collection can be performed by a small
microphone device alone.
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[0024]
Next, embodiments of the present invention will be described with reference to the drawings.
(First Embodiment) FIG. 1 is a cross-sectional view showing an internal configuration of an
embodiment of the microphone device of the present invention (an example in which at least a
part of a microcapsule has an acoustically transparent mesh structure), and FIG. FIG. 6 is a crosssectional view showing a sound collection element of a MEMS structure used here.
[0025]
This microphone device is, as shown in FIG. 1, specified on the basis of first and second sound
collecting elements manufactured using a semiconductor manufacturing process, and output
signals of the first and second sound collecting elements. A signal processing unit for performing
arithmetic processing, the first and second sound collecting elements, and the signal processing
unit are housed, and a part of the sound directed from one sound source to the first sound
collecting element is diffracted by the diffraction. A structure that prevents reaching the second
sound collecting element, and prevents a part of the sound traveling from one sound source
toward the second sound collecting element reaching the first sound collecting element by
diffraction. And a microphone capsule at least a part of which is an acoustically transparent
(acoustically transparent) mesh structure.
[0026]
As described above, the microphone device of the present embodiment adopts a microphone
capsule 90 having an acoustically transparent (acoustically transparent) mesh structure, and is a
MEMS sound pickup device having high accuracy and excellent stability. Is housed in a capsule in
a parallel arrangement, and the capsule is adopted as an acoustically transparent (acoustically
transparent) mesh structure in at least a part of the capsule as a structure for preventing leakage
of diffracted sound The feature is that they are doing.
[0027]
The sound originally travels in a straight line, and no diffraction phenomenon occurs unless there
is an obstruction in the path under a predetermined condition.
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Therefore, the entire capsule 90 has an acoustically transparent (acoustically transparent) mesh
structure (this mesh has a structure having a large number of holes with a diameter that does not
cause adverse effects due to acoustic diffraction), and the sound source The sound coming from
is straight as it is and reaches each sound collection element.
[0028]
As a result, the sound from the sound source travels straight and reaches each sound collection
element without being blocked by the capsule (casing) 90 of the microphone device.
That is, the acoustic paths leading to one sound collection element become P1 and P2 without
being adversely affected by acoustic diffraction, and are integrated. Therefore, it becomes
possible to appropriately set the delay amount and coefficient setting for directivity formation,
and it becomes possible to form good directivity.
[0029]
Further, by processing a material having conductivity such as metal to form a mesh structure, a
shielding effect of electromagnetic wave noise can also be obtained, and therefore no problem
occurs in shielding of electromagnetic noise.
[0030]
In addition, two sound pickups manufactured using a silicon manufacturing process (MEMS
technology) provided on a microcapsule 90 having a sound transmitting mesh structure, a
mounting substrate 65, and a common mounting substrate 65 Elements (capacitive type acoustoelectric conversion elements for converting sound into electric signals) 11a and 11b (the specific
structure will be described with reference to FIG. 2) and impedances of output signals from the
sound collection elements 11a and 11b A signal processing unit (signal processing LSI) 62 that
performs appropriate delay and addition / subtraction after conversion, and bonding wires 63a
to 63d for electrically connecting the sound collection elements 11a and 11b and the signal
processing unit 62 Have.
[0031]
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Capacitive type sound pickup elements (MEMS sound pickup elements) 11a and 11b
manufactured using microfabrication technology (MEMS technology) of silicon LSI are processed
compared to the sound pickup elements manufactured by assembly of mechanical parts The
accuracy is high, and the accuracy of the acoustoelectric conversion is high and stable.
Using this advantage, one microphone device (microphone module) is configured by housing a
sound collection element manufactured using two semiconductor manufacturing processes in the
microphone capsule 90.
However, if there are a plurality of acoustic paths from the sound source to each sound collection
element due to the diffraction of sound, it becomes difficult to form directivity. Therefore, a micro
with a partition 68 for preventing the generation of the acoustic path due to diffraction. The
capsule (casing) is adopted. Thereby, it is possible to realize high accuracy and stable directivity
by using one microphone module in which at least two sound pickup elements are housed in a
capsule.
[0032]
In the microphone device of the present invention, the microcapsules having the sound
transmitting mesh structure have only the acoustic paths P1 and P2 from the sound source 68 to
the respective sound collecting elements 11a and 11b, and a plurality of acoustic paths are
present. It does not occur. Therefore, an electrical signal suitable for signal processing for
providing directivity can be obtained from each of the sound collection elements (11a, 11b).
[0033]
According to the present invention, it is possible to obtain a small microphone module
(microphone device) capable of directional sound collection and stereo sound collection. FIG. 2 is
a cross-sectional view of a device for illustrating the structure of a sound collection element
(MEMS sound collection element) manufactured by the manufacturing process of the silicon LSI
shown in FIG.
[0034]
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10
The configuration of the microphone device of the present embodiment will be described with
reference to FIGS. 1 and 2. FIG. 1 and 2 are cross-sectional views of the microphone device of the
present embodiment. The sound collection element 11a (11b is also the same) includes a
semiconductor substrate 12 including a diaphragm 33 that vibrates according to a change in
sound pressure caused by sound waves, and a back plate 13 disposed opposite to the diaphragm
33 with a gap 16 interposed therebetween. A spacer (electrically insulating film) 14 provided
between the semiconductor substrate 12 and the back plate 13, an electrode 17 provided on the
semiconductor substrate 12, and an electrode 18 provided on the back plate 13 The back plate
13 is provided with a plurality of through holes 15.
[0035]
By using a conductive material (silicon) as the semiconductor substrate 12, electrical conductivity
between the electrode 17 provided on the semiconductor substrate 12 and the diaphragm 33 is
secured. Similarly, by using a conductive material (silicon) as the back plate 13, electrical
continuity with the electrode 18 provided on the back plate 13 is secured.
[0036]
The back plate 13 is made of conductive silicon (e.g., silicon treated to reduce resistance by ion
implantation or the like). The surface of the back plate 13 is provided with a silicon electret film
(not shown) formed by electrically charging a silicon oxide film, whereby a DC bias circuit for
biasing a capacitive transducer is provided. It becomes unnecessary.
[0037]
In order to release the pressure generated by the vibration of the silicon diaphragm 33, the back
plate 13 is intentionally provided with a plurality of air gaps for pressure release, and has a netlike structure. The silicon diaphragm 33 is formed, for example, by etching a part of the bottom
of the silicon substrate 12 having a predetermined thickness to form a recess. However, the
present invention is not limited to this manufacturing method, and for example, a thin silicon film
can be newly grown on the back surface of the silicon substrate 12 provided with a recess to
form the diaphragm 33.
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[0038]
The silicon diaphragm 33 and the back plate 13 are arranged opposite to each other by a
predetermined distance by a spacer 14 formed of an electrically insulating film such as a silicon
oxide film, and a gap is formed between the silicon diaphragm 33 and the back plate 13 16,
which forms a capacitive transducer for converting mechanical vibrations due to pressure waves
or sound waves into electrical signals.
[0039]
Capacitive type sound pickup elements (MEMS sound pickup elements) 11a and 11b
manufactured using microfabrication technology (MEMS technology) of silicon LSI are processed
compared to the sound pickup elements manufactured by assembly of mechanical parts The
accuracy is high, and the accuracy of the acoustoelectric conversion is high and stable.
Therefore, the variation in the sound collection accuracy of the two sound collection elements
can be minimized, and a good and stable directivity can be formed.
[0040]
Next, the process until the structure of the microphone device of the present embodiment shown
in FIG. 1 is found will be described with reference to FIGS. FIG. 4 is a cross-sectional view of an
example of the microphone device for explaining the process until the structure of the
microphone device of the present embodiment shown in FIG. 1 is found. In FIG. 4, the same
reference numerals as in FIGS. 1 and 2 denote the same parts in FIG. As shown in FIG. 4, the
MEMS sound collection elements 11 a and 11 b are mounted on a common mounting substrate
65, and the sound collection elements 11 a and 11 b are microphone capsules 64 provided with
one sound hole 71 at the center. It is covered by.
[0041]
5 (a) and 5 (b) are for explaining the process until the structure of the microphone device of the
present embodiment shown in FIG. 1 is conceived (in particular, different acoustic paths are
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required for directional sound collection) And a cross-sectional view showing the positional
relationship between the microphone device and the sound source. In FIG. 5, parts common to
FIGS. 1 and 2 are assigned the same reference numerals.
[0042]
As shown in FIGS. 5 (a) and 5 (b), when there are one sound hole 71, acoustic paths (P3, P4) from
arbitrary sound sources 68a, 68b to each of the sound collection elements 11a, 11b. Because the
arrival distances of) are equal, sensitivity can not be made directional.
[0043]
6 (a) and 6 (b) are for explaining the process until the structure of the microphone device of the
present embodiment shown in FIG. 1 is conceived (in particular, the acoustic path when a
plurality of sound holes are provided) Is a cross-sectional view showing the positional
relationship between the microphone device and the sound source (for explaining that the
directional sound collection becomes difficult).
In FIG. 6, the same reference numerals as in FIGS. 1 and 2 denote the same parts in FIG.
[0044]
As illustrated, when a plurality of sound holes (73 a, 73 b) are provided in the microcapsule 64,
there are a plurality of acoustic paths for reaching each of the sound collection elements 11 a, 11
b from the sound source 68. That is, in the case of FIG. 6A, there are two acoustic paths P5 and
P6, and in the case of FIG. 6B there are two acoustic paths P7 and P8.
[0045]
Since different acoustic paths have different frequency characteristics and delay characteristics,
the electric signals output from the sound collection elements 11a and 11b become complicated,
and the electric signals suitable for signal processing for giving sensitivity to sensitivity are
collected It can not be obtained from the elements 11a and 11b.
[0046]
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Under this consideration, again referring back to FIG. 1 and analyzing the structure, the partition
68 provided at the center of the microphone capsule 64 airtightly separates the space in which
each of the sound pickup elements 1a and 11b is located. It can be seen that one sound hole 67a,
67b is provided for each space.
[0047]
This structure prevents the sound that has passed through the sound holes (67a, 67b) for one of
the sound collection elements from reaching the other sound collection element by diffraction
and reaching the sound path (P1, P2). Can be integrated.
Therefore, it becomes possible to appropriately set the delay amount and coefficient setting for
directivity formation, and it becomes possible to form good directivity.
Further, the point that only one sound hole is provided for each space is advantageous in terms
of maintaining the strength of the microcapsule 64 as a casing, maintaining a high
electromagnetic shielding effect and a dustproof effect.
[0048]
As described above, in the microphone device of the present embodiment, the MEMS sound
pickup elements manufactured with the MEMS technology and having high accuracy and
excellent stability are accommodated in a capsule in a state of being arranged in parallel, and the
capsule Using a compact microphone module in which at least two sound pickup elements are
housed in a capsule by unifying the acoustic path as a structure (a sound transmitting mesh
structure) for preventing leakage of diffracted sound. It becomes possible to easily realize high
precision and stable directivity.
[0049]
Second Embodiment FIGS. 3A and 3B are a cross-sectional view and process explanatory views
showing another example of the microphone device of the present invention.
In FIG. 3, the same reference numerals are given to parts common to the drawings described in
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the first embodiment. 3 (a) and 3 (b) are openings (parts necessary for causing sound to come to
the diaphragm of the sound collection elements 11a and 11b, in particular) in a part of the metal
microcapsules (housing) 64 (in particular, 67c, 67d, 67e) are provided, and the mesh sheets 91
and 92a, 92b are provided only in the openings. The mesh sheets 91 and 92a, 92b are adhered
to, for example, metal microcapsules (housing) 64 using an adhesive.
[0050]
As the mesh sheets 91 and 92a and 92b, for example, a rough mesh sheet (fabric) is used. As the
coarse mesh sheet, a knitted mesh with stitches, a punched mesh sheet in which fine small holes
are perforated in a thin metal sheet, or the like can be used. The roughness is suitably about 1
pitch width 0.5 mm to 5.0 mm.
[0051]
In this way, by making at least a part of the microcapsules into an acoustically transparent
(acoustically transparent) mesh structure, the sound from the sound source goes straight as it is
without being blocked by the capsule of the microphone device. It reaches the sound collection
element, and the acoustic path to one sound collection element is unified.
[0052]
That is, also in the microphone device of the present embodiment, the acoustic path from the
sound source 68 to each of the sound collection elements (11a, 11b) is one straight line (P9,
P10) as in the above embodiment. An electric signal suitable for signal processing for providing
directivity can be obtained from the sound collection element, and the same effect as that of the
first embodiment can be obtained.
That is, appropriate setting of the delay amount and coefficient setting for directivity formation
can be performed, and good directivity can be formed. Moreover, the shielding effect of
electromagnetic wave noise can be obtained by using a conductive mesh.
[0053]
In the above embodiment, an example in which a microphone device capable of directional sound
collection and stereo sound collection is configured using two sound collection elements has
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been described, but the present invention is not limited to this. It is also possible to realize higher
directivity by using the above sound collection elements.
[0054]
In the microphone device using three or more sound pickup elements, when the mesh structured
microphone capsule described in the first embodiment is used, the structure can be simplified,
and the device can be manufactured inexpensively.
[0055]
As described above, according to the present invention, a highly accurate and stable MEMS
sound pickup device manufactured using MEMS technology is accommodated in a capsule in a
state of being arranged in parallel, and the capsule is Using a compact microphone module in
which at least two sound pickup elements are housed in a capsule by unifying the acoustic path
as a structure (a structure having an acoustically transparent mesh) for preventing leakage of
diffracted sound It is possible to easily realize high precision and stable directivity.
[0056]
That is, by separating the space in which each of the first sound collecting element and the
second sound collecting element is airtightly separated by the partition provided in the capsule,
the sound passing through the sound hole for one of the sound collecting elements However, due
to diffraction, it is possible to prevent the other sound pickup element from coming around and
reaching, and to unify the acoustic path.
Therefore, it becomes possible to appropriately set the delay amount and coefficient setting for
directivity formation, and it becomes possible to form good directivity.
[0057]
Also, by making at least a part of the capsule acoustically transparent (acoustically transparent)
mesh structure, the sound from the sound source goes straight as it is without being blocked by
the capsule of the microphone device, and each sound pickup element The sound path leading to
one sound pickup element is unified.
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Therefore, it becomes possible to appropriately set the delay amount and coefficient setting for
directivity formation, and it becomes possible to form good directivity.
Moreover, the shielding effect of electromagnetic wave noise can be obtained by using a
conductive mesh.
[0058]
In the above embodiment, the sound pickup element chip and the signal processing circuit chip
are formed by mounting on the substrate 65, but in a state where the MEMS sound pickup
elements having high accuracy and excellent stability are arranged in parallel. It may be LSI.
Furthermore, the acoustic path may be integrated as a structure that is housed in a microcapsule
formed by a MEMS process and that the microcapsule is prevented from leaking of diffracted
sound. That is, as a structure for preventing the leakage of the diffraction acoustic, the silicon
microcapsules formed by the MEMS process using the same silicon substrate as the LSI chip on
which the first and second sound pickup elements and the signal processing circuit are mounted
are adopted. You may
[0059]
In the above embodiment, an example was described in which a microphone device capable of
directional sound collection and stereo sound collection using two sound collection elements was
described, but the present invention is not limited to this, and three It is also possible to realize
higher directivity by using the above sound collection elements. In the microphone device using
three or more sound pickup elements, the use of the microcapsule described in Embodiment 2
makes it possible to simplify the structure and to manufacture inexpensively.
[0060]
As described above, according to the present invention, a highly accurate and stable MEMS
sound pickup device manufactured using MEMS technology is accommodated in a capsule in a
state of being arranged in parallel, and the capsule is A compact structure in which at least two
sound pickup elements are accommodated in a capsule by unifying the acoustic path as a
structure (a structure having a partition that airtightly separates each sound pickup element),
which prevents leakage of diffracted sound. It becomes possible to easily realize high accuracy
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and stable directivity by using a microphone module.
[0061]
Also, by accommodating the signal processing unit in the capsule, it is possible to obtain a onemodule microphone device capable of highly accurate and stable directional sound collection
(including stereo sound collection).
Also, by mounting the sound pickup element and the signal processing unit on a common
substrate and covering the capsule on the substrate to form one module, a compact one-module
microphone device can be obtained.
[0062]
According to the present invention, it is possible to provide a microphone device capable of
highly accurate and stable directional sound collection and stereo sound collection with a small
microphone device alone.
[0063]
The present invention has the effect of enabling highly accurate and stable directional sound
collection and stereo sound collection with a small microphone device alone, and therefore, a
very small microphone device (for example, a very small electret condenser microphone array)
Useful as a module).
[0064]
Cross-sectional view showing the microphone device of the first embodiment of the present
invention Cross-sectional view of a device for describing the structure of a sound collection
element (MEMS sound collection element) manufactured by the manufacturing process of silicon
LSI shown in FIG. FIGS. 6A and 6B show a microphone device according to a second embodiment
of the present invention, wherein FIGS. 6A and 6B show a variation (modification) of the
structure of the microcapsule according to the first embodiment shown in FIG. Cross-sectional
views (a) and (b) of an example of the microphone device for explaining the process until it is
conceived explain the process until the structure of the microphone device of the present
embodiment shown in FIG. 1 is conceived. The cross-sectional views (a) and (b) showing the
positional relationship between the microphone device and the sound source (in particular, for
explaining that the directional sound collection requires a different sound path) are shown in FIG.
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For explaining the process until the structure of the microphone device of the present
embodiment shown in FIG. 1 is conceived (especially, when a plurality of sound holes are
provided, the acoustic path becomes complicated and directional sound collection becomes
difficult A cross-sectional view showing the positional relationship between the microphone
device and the sound source).
Explanation of sign
[0065]
11a, 11b Sound collection element 12 Silicon semiconductor substrate 13 Back plate 14 Spacer
(electrical insulating film) 15 Through hole for air escape 16 Air gap 17, 18 Electrode 32a, 32b
First and second sound collection element 32 LSI 34 Silicon microcapsule 33 Vibrator (for
example, silicon diaphragm made of doped silicon) 63a to 63d bonding wire 64 microphone
capsule (casing, case) 67a, 67b sound hole 68 sound source
10-05-2019
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