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DESCRIPTION JP2010136406

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DESCRIPTION JP2010136406
[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, a partition 68 is provided at the center of the capsule 64, and one sound hole 67a, 67b
is provided for one space separated by the partition 68. As a result, the sound arriving at the
sound hole for one of the sound collection elements is not diffracted and does not reach the
other sound collection element, and the sound paths (P1, P2) are unified, and appropriate
calculation processing is performed. Directional sound collection becomes possible. [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).
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The structure of the conventional example described in FIG. 1 (b) of Patent Document 1 will be
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 are
housed in a common capsule) described in FIG. 1 (b) of Patent Document 1.
[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).
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[0006]
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.
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This point hinders the realization of the formation of high precision and stable directivity.
[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]
The above object of the present invention is achieved by the following constitution.
(1) A first sound collecting element having a semiconductor substrate, a first diaphragm formed
on the semiconductor substrate and disposed to face each other, and a first back plate, and the
semiconductor substrate A second sound pickup element having a second diaphragm and a
second back plate formed on the semiconductor substrate and disposed to face each other, the
first sound pickup element and the first sound pickup element A microphone capsule mounted
on the semiconductor substrate so as to cover the second sound collecting element; and an
internal space formed by the microphone capsule and the semiconductor substrate, the first
sound collecting element and A microphone which has a partition separating the second sound
collection element, and the microphone capsule has a sound hole at a position corresponding to
each of the first sound collection element and the second sound collection element. apparatus. (2)
The microphone device according to (1), wherein the microphone capsule and the partition wall
are integrated. (3) The microphone device according to (1) or (2), wherein the first sound
collecting element and the second sound collecting element are covered by a single microphone
capsule. Microphone device. (4) The microphone device according to any one of (1) to (3),
wherein the microphone capsule is a silicon microphone capsule. (5) The microphone device
according to any one of (1) to (4), wherein the partition wall is provided at a central portion of
the microphone capsule when the microphone capsule is viewed from above Microphone device
characterized by (6) The microphone device according to any one of (1) to (5), wherein a signal
processing unit is further integrated on the semiconductor substrate. (7) The microphone device
according to (6), wherein the first sound collecting element and the second sound collecting
element, and the signal processing unit are connected in the semiconductor substrate or on the
surface of the semiconductor substrate. Microphone device. (8) The microphone device according
to (6) or (7), wherein the signal processing unit performs delay processing on output signals of
the first sound collection element and the second sound collection element. A microphone device
that performs addition and subtraction processing to realize directional sound collection. (9) The
microphone device according to any one of (6) to (8), wherein the second sound collection
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element is connected to the signal processing unit to which the first sound collection element is
connected. Microphone apparatus characterized by
(10) The microphone device according to any one of (1) to (9), wherein the sound holes are
orthogonal to the first diaphragm and the second diaphragm, respectively. A microphone device
that is formed as follows. (11) The microphone device according to any one of the above (1) to
(10), wherein the back plate is made of conductive silicon. (12) The microphone device according
to any one of (1) to (11), wherein the diaphragm is made of doped silicon. (13) The microphone
device according to any one of (1) to (12), wherein the first sound collecting element and the
second sound collecting element are each manufactured using a semiconductor manufacturing
process. Microphone apparatus characterized by (14) The microphone device according to any
one of (1) to (13), wherein the first back plate and the second back plate are separated. (15) The
microphone device according to any one of (1) to (14), wherein the semiconductor substrate is
provided at a position corresponding to the first diaphragm and the second diaphragm. And a
second through hole. (16) The microphone device according to (15), wherein the first diaphragm
and the second diaphragm are exposed in the first through hole and the second through hole,
respectively. Microphone device characterized in that
[0012]
The following modes are also effective. 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, 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 second sound
collection A microphone capsule having a structure for preventing reaching an element and
preventing a part of sound directed from one sound source to the second sound collecting
element from reaching the first sound collecting element by diffraction; And.
[0013]
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
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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.
[0014]
Further, according to the present invention, in the above-mentioned microphone device, the
microphone capsule has a partition which is separated into a plurality of spaces so as to spatially
separate and accommodate each of the first and second sound collection elements, At least one
sound hole is provided in each space for accommodating the first and second sound collection
elements. According to the above configuration, the partition provided in the capsule airtightly
separates the space in which the first sound collecting element and the second sound collecting
element are located, and at least one sound hole is provided in each space. It is Due to the
presence of the partition wall, the sound passing through the sound hole for one of the sound
collection elements does not move around and reach the other sound collection element by
diffraction, and a plurality of sounds with respect to one sound collection element There is no
path present. Therefore, it becomes possible to set the delay amount and coefficient for
directivity formation appropriately and to form good directivity.
[0015]
Further, according to the present invention, in the 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).
[0016]
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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 microphone capsule
having an opening formed by a MEMS process, which 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 semiconductor 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
having a partition that airtightly separates each sound pickup element) It becomes possible to
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easily realize high precision and stable directivity.
[0020]
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.
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 (metal) mesh.
[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). 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.
[0022]
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.
[0023]
BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the microphone apparatus of
Embodiment 1 of this invention, and (a) is an internal structure of an example (an example which
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has a structure which has a partition which divides the space where each sound collection
element is located) of this invention. (B) is a cross-sectional view showing the structure of the
capsule (the structure in which the outer casing and the partition wall are integrated). The sound
pickup element (MEMS sensor manufactured by the manufacturing process of silicon LSI shown
in FIG. FIG. 6 is a cross-sectional view showing a microphone device according to a second
embodiment of the present invention, where (a) is an example of each of the microphone devices
according to the present invention (each sound collecting element and signal). Fig. 2 is a crosssectional view showing the internal configuration of the processing circuit in one chip and using
a MEMS silicon microphone capsule), Fig. 2 (b) is an explanatory drawing of the assembly of the
microphone device of the present embodiment shown in Fig. 1 The cross-sectional views (a) and
(b) of an example of the microphone device for explaining the process until the construction is
conceived are the processes until the structure of the microphone device of the present
embodiment shown in FIG. 1 is conceived. Cross-sectional views (a) and (b) showing the
positional relationship between the microphone device and the sound source are for illustration
(especially for illustrating that different acoustic paths are required for directional sound
collection). 1 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, and a cross-sectional view showing the structure of the
conventional example.
[0024]
Next, embodiments of the present invention will be described with reference to the drawings.
(First Embodiment) FIG. 1A is a cross-sectional view showing an internal configuration of an
example of the microphone device of the present invention (an example having a structure
having a partition that divides a space in which each sound collection element is located) b) is a
cross-sectional view showing the structure of the microphone capsule (the structure in which the
outer casing and the partition wall are integrated).
[0025]
This microphone device is, as shown in FIG. 1A, based on 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
predetermined arithmetic processing, the first and second sound collecting elements, and the
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signal processing unit, and part of the sound directed from one sound source toward the first
sound collecting element While preventing reaching the second sound collecting element by
diffraction, it is possible that part of the sound directed from one sound source to the second
sound collecting element reaches the first sound collecting element by diffraction. And a
microphone capsule having a preventing structure.
[0026]
In the above microphone device, the microphone capsule has a partition which is separated into
a plurality of spaces so as to spatially separate and accommodate each of the first and second
sound collecting elements, and the first and second microphone assemblies At least one sound
hole is provided in each of the spaces for housing the sound pickup elements.
In addition, the microphone capsules 64 provided with the sound holes 67 a and 67 b and
divided into a plurality of spaces by the partition wall 68 provided at the center, the mounting
substrate 65, and silicon are provided on the common mounting substrate 65. Two sound pickup
elements (capacitive type acousto-electrical conversion elements for converting sound into
electric signals) 11a and 11b manufactured using a process (MEMS technology) (A specific
structure will be described with reference to FIG. 2. Signal processing unit (signal processing LSI)
62 that performs appropriate delay and addition / subtraction after impedance conversion of the
output signals of the sound collection elements 11a and 11b, the sound collection elements 11a
and 11b, and the signal processing unit 62. And bonding wires 63a to 63d for electrical
connection.
[0027]
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
Taking advantage of this advantage, one microphone device (microphone module) is configured
by housing the sound pickup elements manufactured using two semiconductor manufacturing
processes in the microphone capsule 64. 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
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difficult to form directivity, so a microphone with a partition wall 68 for preventing 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.
[0028]
As shown in FIG. 1B, the microphone capsule 64 is provided with a partition 68 which airtightly
separates the space in which the sound collection elements 11a and 11b are located, and the
main surface of the microphone capsule 64 is separated by the partition 68 One sound hole 67a,
67b) is provided for one space to be formed. The number of sound holes may be increased. As
the number of sound holes increases, the transparency of sound from the sound source increases
and the diffraction prevention effect improves.
[0029]
The positional relationship between the sound collection element 11a and the sound hole 67a
and the positional relationship between the sound collection element 11b and the sound hole
67b are the same, and in each space, the sound collection elements 11a and 11b are neatly
arranged at predetermined positions .
[0030]
In addition, the microphone capsule 64 is made of a conductive material (for example, metal),
which can provide a shielding effect of electromagnetic noise.
[0031]
Further, it is desirable that the partition 66 be a material capable of absorbing vibration, or be
processed such that a material capable of absorbing vibration is attached to the surface thereof.
Due to the presence of the partition wall 68, in the microphone device of the present invention,
the acoustic paths from the sound source 68 to the respective sound collecting elements 11a and
11b are only P1 and P2, and a plurality of acoustic paths do not occur.
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Therefore, an electrical signal suitable for signal processing for providing directivity can be
obtained from each of the sound collection elements (11a, 11b).
[0032]
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.
[0033]
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.
[0034]
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.
[0035]
The back plate 13 is made of conductive silicon (e.g., silicon treated to reduce resistance by ion
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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.
[0036]
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 150 for pressure release, and has a
mesh-like 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.
[0037]
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.
[0038]
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.
[0039]
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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.
[0040]
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
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.
[0041]
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.
[0042]
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.
[0043]
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As illustrated, when a plurality of sound holes (73 a, 73 b) are provided in the microphone
capsule 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.
[0044]
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.
[0045]
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.
[0046]
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 microphone capsule 64 as a casing, maintaining a high
electromagnetic shielding effect and a dustproof effect.
[0047]
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
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excellent stability are accommodated in a capsule in a state of being arranged in parallel, and the
capsule A compact structure in which at least two sound pickup elements are housed in a capsule
by unifying the acoustic path as a structure (a structure having a partition that airtightly
separates each sound pickup element) to prevent leakage of diffracted sound. It is possible to
easily realize high precision and stable directivity by using a microphone module.
[0048]
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
the first embodiment. In the microphone device of the second embodiment, the first and second
sound collection elements 32a and 32b and the signal processing unit (not shown) are integrated
into an LSI on the same silicon substrate, and the LSI 32 is processed by a MEMS process. It is
formed by covering a silicon substrate with a silicon microphone capsule 34 formed using a
MEMS process so as to have a partition having the formed opening, thereby forming a very small
and thin microphone device. Further, here, two sound holes 67a and 67b are formed in each
room.
[0049]
Furthermore, it is possible to make an LSI in a state in which MEMS sound pickup elements with
high accuracy and excellent stability are arranged in parallel, store them in a microphone capsule
formed by the MEMS process, and prevent the microphone capsule from leaking diffraction
sound. The microphone device of the first embodiment is the same as the microphone device of
the first embodiment in that the acoustic path is integrated as one structure. However, in the
present embodiment, as a structure for preventing the leakage of the diffracted sound, it is
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. The
microphone microphone capsule 34 is employed, which differs from the microphone device of
the above embodiment in this respect.
[0050]
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That is, also in the microphone device of the present embodiment, as in the above embodiment,
the acoustic path from the sound source 68 to each sound pickup element (31a, 31b) is one
straight line, and therefore, has directivity. An electrical signal suitable for signal processing to be
generated 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.
[0051]
Although not shown in the drawings, the signal processing circuit is integrated in the LSI chip,
and the electrical connection between each of the sound collection elements (31a, 31b) and the
signal processing circuit is achieved in or on the silicon substrate. Therefore, wire bonding is also
unnecessary, and miniaturization and high integration can be achieved.
[0052]
Further, at the time of mounting, as shown in the assembly explanatory view of FIG. 3B, the
silicon wafer S1 constituting the LSI chip and the silicon wafer S2 constituting the silicon
microphone capsule are bonded by direct bonding at wafer level.
Finally, dicing is performed to divide into individual microphone devices. As a result, it is possible
to form a small-sized microphone device with good alignment and requiring only one operation.
Although not shown, the signal extraction terminal is formed on the back side of the LSI chip. In
this way, it is possible to form a small and microphone device with good directivity. This
configuration can reduce wasted space and realize a very compact microphone device having a
directional sound collecting function.
[0053]
In the above embodiment, the signal processing circuit is formed on the LSI chip side. However,
by forming the signal processing circuit on the silicon microphone capsule side, the partition wall
portion can also be used for the circuit forming portion, which is more compact. In addition to
the above, it is possible to improve manufacturing workability. In this case, the signal extraction
terminal may be formed on the silicon microphone capsule side. By bonding at the wafer level,
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mechanical strength can be improved by bonding. Thus, the substrate 65 can be omitted.
[0054]
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.
[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 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
and stable directivity by using a microphone module.
[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]
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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.
[0058]
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.
[0059]
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).
[0060]
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 microphone capsule 33 diaphragm
(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 S1, S2 silicon wafer
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