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JP2009130619

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This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
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DESCRIPTION JP2009130619
PROBLEM TO BE SOLVED: To provide a microphone system having a function of collecting a
target voice with high sensitivity and removing sounds other than the target voice, a voice input
device, and a method of manufacturing them. SOLUTION: The first and second microphones (10,
20) are connected to the first and second reference positions (100) relative to the microphone
system on the basis of a sound source position scheduled by the microphone system. The angle
between the perpendicular (120) down to a straight line (110) passing through the position of
the second microphone and the straight line connecting the installation position of the first and
second microphones (10, 20) and the reference position (100) It arrange | positions so that it
may become the predetermined angle set so that the sensitivity with respect to the sound from a
reference (100) may become more than a predetermined ratio with respect to the maximum
value of a directional characteristic. [Selected figure] Figure 4
Microphone system, voice input device and manufacturing method thereof
[0001]
The present invention relates to a microphone system, an audio input device, and methods of
manufacturing them.
[0002]
It is preferable to collect only a target voice (user's voice) at the time of a telephone call or the
like, voice recognition, voice recording, and the like.
04-05-2019
1
However, in the use environment of the voice input device, sounds other than the intended voice
such as background noise may be present. Therefore, development of a voice input device having
a function of removing noise is in progress.
[0003]
As a technique for removing noise in a use environment in which noise is present, a method is
known which removes noise by making the microphone have a sharp directivity.
[0004]
Further, in recent years, the miniaturization of electronic devices has progressed, and techniques
for miniaturizing voice input devices have become important.
Japanese Patent Laid-Open No. 7-322388
[0005]
As a directional microphone, a differential microphone is known that generates and uses a
differential signal indicating the difference between voltage signals from two microphones. FIGS.
13A and 13B are diagrams schematically showing regions showing directivity characteristics of a
normal single microphone and a differential microphone. The sound pressure level (the
sensitivity of the microphone) with respect to the direction of the sound source is indicated by
the distance from the center to the outer edge of the area 900, the area 910-1, and the area 9102.
[0006]
FIG. 13A is a diagram showing directivity characteristics in the case where a single
omnidirectional microphone is disposed at the center. In the case of the nondirectional
microphone, there is no directivity, and the sound pressure level (the sensitivity of the
microphone) is constant in each direction.
04-05-2019
2
[0007]
FIG. 13B is a diagram showing the directivity characteristic of a differential microphone
composed of two microphones. The relationship between the position and angle of the two
microphones is, as shown in FIG. 14, that the perpendicular direction to the straight line
connecting the two microphones is 0 degree. The directional characteristics of the differential
microphones are such that the sound pressure level (microphone sensitivity) is maximum in the
90 degree direction and 270 degree direction, and the sound pressure level (microphone
sensitivity) is 0 in the 0 degree direction and 180 degree direction. It becomes directivity.
[0008]
Therefore, in order to collect only target voice using a differential microphone, the arrangement
of the differential microphone with respect to the sound source is important.
[0009]
The present invention has been made in view of the circumstances as described above, and a
microphone system having a function of collecting a target voice with high sensitivity and
removing a sound other than the target voice, a voice input device, and the like The purpose is to
provide a manufacturing method.
[0010]
(1) A microphone system according to the present invention includes a first microphone, a
second microphone, a first voltage signal acquired by the first microphone, and a second voltage
acquired by the second microphone. And a differential signal generation unit configured to
receive a voltage signal from the circuit and generate a differential signal indicating a difference
between the first and second voltage signals, the first and second microphones comprising: A
vertical line extending from a reference position set relative to the microphone system based on
a sound source position scheduled by the microphone system to a straight line passing through
the positions of the first and second microphones; The angle between the installation position of
the second microphone and the straight line connecting the reference position is the sensitivity
to the sound from the reference position. It is characterized in that it is disposed so as to be a
predetermined angle set to be a predetermined ratio or more with respect to the maximum value
of the sex.
[0011]
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3
The position of the microphone may be the position of the sound pickup port when the
microphone has a sound pickup port, or may be the position of the diaphragm when the
microphone does not have a sound pickup port.
[0012]
The installation positions of the first and second microphones include, for example, the position
of the first microphone, the position of the second microphone, the midpoint between the
positions of the first and second microphones, and the other of the first and second microphones.
It may be a representative point selected from the vicinity.
[0013]
The predetermined ratio is, for example, within about -6 dB (more than -6 dB and less than 0 dB)
from the maximum value of sensitivity, and more preferably within about -3 dB (more than -3 dB
and more than 0 dB). The following range may be adopted.
[0014]
According to this microphone system, by arranging the two microphones so that the sensitivity to
the sound from the reference position becomes a predetermined ratio or more with respect to the
maximum value of the directional characteristic, the target voice can be Sound can be collected
with high sensitivity, and sounds other than the target voice can be removed by the directivity
and distance attenuation characteristics of the differential microphone.
[0015]
(2) In this microphone system, the predetermined angle may be arranged to be any value in the
range of 30 degrees or more and 150 degrees or less or 210 degrees or more and 330 degrees
or less.
[0016]
According to this microphone system, the sensitivity to the sound from the reference position can
be within about -6 dB from the maximum value of the sensitivity.
[0017]
(3) In this microphone system, the first and second microphones may be configured as
semiconductor devices.
04-05-2019
4
[0018]
For example, the first and second microphones may be silicon microphones (Si microphones).
The first and second microphones may be configured as one semiconductor substrate.
At this time, the first and second microphones and the difference signal generation unit may be
configured as one semiconductor substrate.
In addition, the first and second microphones and the difference signal generation unit may be
configured as so-called MEMS (Micro Electro Mechanical Systems).
In addition, as the vibrating film, an inorganic piezoelectric thin film or an organic piezoelectric
thin film may be used to perform acousto-electrical conversion by the piezoelectric effect.
[0019]
According to this microphone system, by configuring the microphone as a semiconductor device,
the entire microphone system can be miniaturized.
[0020]
(4) A voice input device including the microphone system and a speaker, wherein the reference
position may be set based on the position of the speaker.
[0021]
According to this voice input device, the speaker's voice can be collected with high sensitivity,
and sounds other than the speaker's voice can be removed by the directivity of the differential
microphone and the attenuation characteristics due to the distance.
[0022]
(5) In this voice input device, the reference position range in which the reference position is set
has a range from a first reference position closest to the speaker to a second reference position
04-05-2019
5
farthest to the speaker A first boundary position of a first perpendicular drawn from the first
reference position to a straight line passing through the positions of the first and second
microphones, a first boundary position, and the first and second reference positions from the
second reference position; A foot of a second perpendicular drawn to a straight line passing
through the position of the second microphone is taken as a second boundary position, and a
straight line connecting the first perpendicular, the installation position of the first and second
microphones, and the sound source A range in which the angle between the two does not satisfy
the predetermined angle is defined as a first prohibited range, and an angle formed by a straight
line connecting the second perpendicular, the installation position of the first and second
microphones, and the sound source is the A range that does not satisfy the predetermined angle
A second prohibited range; a range from the first boundary position to the second boundary
position is a third prohibited range; and the first and second microphones are the first to third
microphones. It may be arranged outside the prohibited range.
[0023]
In consideration of a standard human face size, for example, the distance from the speaker to the
first boundary position may be about 100 mm, and the distance from the speaker to the second
boundary position may be about 150 mm.
In addition, in consideration of the normal use form of the voice input device, for example, the
length from the reference position to the middle point of the first and second microphones can
be about 50 mm.
[0024]
According to this voice input device, even when the reference position is set with a certain range,
the speaker's voice can be collected with high sensitivity, and the sounds other than the speaker's
voice are of the differential microphone. It can be eliminated by directivity and distance
attenuation characteristics.
[0025]
(6) In this voice input device, the predetermined angle may be arranged to be any value in the
range of 30 degrees or more and 150 degrees or less or 210 degrees or more and 330 degrees
or less.
04-05-2019
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[0026]
According to this voice input device, it is possible to provide a voice input device whose
sensitivity to the speaker's voice is within about -6 dB from the maximum value of the sensitivity.
[0027]
(7) In this voice input device, the first and second microphones are positioned such that the
distance between the speaker and the installation position of the first and second microphones is
0 mm or more and 75 mm or less or 175 mm or more. It may be arranged.
[0028]
According to this voice input device, it is possible to provide a voice input device whose
sensitivity to the speaker's voice is within about -6 dB from the maximum value of the sensitivity.
[0029]
(8) A method of manufacturing a microphone system according to the present invention includes:
a first microphone, a second microphone, a first voltage signal acquired by the first microphone,
and an acquisition by the second microphone A differential signal generation unit that receives a
second voltage signal and generates a difference signal indicating a difference between the first
and second voltage signals; The second microphone is a vertical line drawn down from the
reference position set relative to the microphone system based on the sound source position
scheduled by the microphone system to a straight line passing the positions of the first and
second microphones And the angle between the installation position of the first and second
microphones and the straight line connecting the reference position is the sound from the
reference position It arranges so that it may become the predetermined angle set up so that the
sensitivity to may become more than a predetermined rate to the maximum value of directivity
characteristic.
[0030]
According to the present invention, the target voice is high by arranging the two microphones so
that the sensitivity to the sound from the reference position is a predetermined angle set to be a
predetermined ratio or more with respect to the maximum value of the directional characteristic.
It is possible to provide a method of manufacturing a microphone system which can be collected
with sensitivity and sound other than the target voice can be removed by the directivity and
distance attenuation characteristics of the differential microphone.
04-05-2019
7
[0031]
(9) In this method of manufacturing a microphone system, the predetermined angle may be
arranged to be any value within the range of 30 degrees or more and 150 degrees or less or 210
degrees or more and 330 degrees or less.
[0032]
According to the method of manufacturing the microphone system, it is possible to provide a
method of manufacturing the microphone system in which the sensitivity to the sound from the
reference position can be within about -6 dB from the maximum value of the sensitivity.
[0033]
(10) A method of manufacturing a voice input device according to the present invention includes
a first microphone, a second microphone, a first voltage signal acquired by the first microphone,
and an acquisition by the second microphone. An audio input device including: a microphone
system including: a differential signal generation unit that receives a second voltage signal
generated and generates a differential signal indicating a difference between the first and second
voltage signals; The first and second microphones are selected from a reference position set
relative to the microphone system based on a sound source position scheduled by the
microphone system. Between a straight line passing through the position of the microphone and
a straight line connecting the installation position of the first and second microphones and the
reference position. The angle is set to be a predetermined angle set so that the sensitivity to the
sound from the reference position is a predetermined ratio or more with respect to the maximum
value, and the reference position is set based on the position of the speaker. It is characterized by
[0034]
According to the method of manufacturing the voice input device, the voice of the speaker can be
collected with high sensitivity, and sounds other than the voice of the speaker can be removed by
the directivity and distance attenuation characteristics of the differential microphone. A method
of manufacturing a voice input device can be provided.
[0035]
(11) In this method of manufacturing a voice input device, a reference position range in which
the reference position is set is a range from a first reference position closest to the speaker to a
second reference position farthest to the speaker The foot of a first perpendicular drawn from
the first reference position to a straight line passing through the positions of the first and second
04-05-2019
8
microphones is referred to as a first boundary position, and the second reference position from
the second reference position. The foot of a second perpendicular drawn to a straight line
passing through the positions of the first and second microphones is taken as a second boundary
position, the first perpendicular, the installation positions of the first and second microphones,
and the sound source A range in which an angle formed by the straight line connecting the two
does not satisfy the predetermined angle is a first prohibited range, and the second
perpendicular line and a straight line connecting the installation position of the first and second
microphones and the sound source The angle is the predetermined angle A range which is not
satisfied is set as a second prohibited range, a range from the first boundary position to the
second boundary position is set as a third prohibited range, and the first and second
microphones It may be arranged outside the prohibited range of 3.
[0036]
According to the method of manufacturing the voice input device, even when the reference
position is set with a certain range, the voice of the speaker can be collected with high sensitivity,
and the sounds other than the speaker's voice are different. It is possible to provide a method of
manufacturing an audio input device that can be eliminated by the directivity and distance
attenuation characteristics of the dynamic microphone.
[0037]
(12) In this method of manufacturing a voice input device, the first and second microphones are
arranged such that the distance between the speaker and the installation position of the first and
second microphones is 0 mm or more and 75 mm or less or 175 mm or more It may be arranged
at
[0038]
According to the method of manufacturing the voice input device, it is possible to provide a
method of manufacturing the voice input device in which the sensitivity to the speaker's voice
can be within about -6 dB from the maximum value of the sensitivity.
[0039]
Hereinafter, embodiments to which the present invention is applied will be described with
reference to the drawings.
04-05-2019
9
However, the present invention is not limited to the following embodiments.
Further, the present invention includes any combination of the following contents.
[0040]
1.
Microphone System and Method of Manufacturing the Same First, the configuration of a
microphone system 1 according to an embodiment to which the present invention is applied will
be described with reference to FIGS. 1 to 6.
The microphone system 1 described below may be applied to, for example, voice communication
devices such as mobile phones, public phones, transceivers, and headsets, or recording devices,
amplifier systems (loudspeakers), microphone systems, etc. it can.
[0041]
FIG. 1 is a diagram showing an example of the configuration of a microphone system according
to an embodiment to which the present invention is applied.
The microphone system according to the present embodiment includes a first microphone 10
having a first diaphragm 12 and a second microphone 20 having a second diaphragm 22.
Here, the microphone is an electroacoustic transducer that converts an acoustic signal into an
electrical signal.
The first and second microphones 10 and 20 may be converters that output the vibrations of the
first and second vibrating films 12 and 22 (vibrating film), respectively, as voltage signals.
04-05-2019
10
[0042]
In the microphone system 1 according to the present embodiment, the first microphone 10
generates a first voltage signal.
Also, the second microphone 20 generates a second voltage signal.
That is, voltage signals generated by the first and second microphones 10 and 20 may be
referred to as first and second voltage signals, respectively.
[0043]
The mechanism of the first and second microphones 10 and 20 is not particularly limited.
FIG. 2 shows the structure of a condenser microphone 50 as an example of a microphone
applicable to the first and second microphones 10 and 20. As shown in FIG.
The condenser microphone 50 has a vibrating film 52.
The vibrating film 52 is a film (thin film) that vibrates upon receiving an acoustic wave, has
conductivity, and forms one end of an electrode.
The condenser microphone 50 also has an electrode 54.
The electrode 54 is disposed to face the vibrating membrane 52.
Thus, the diaphragm 52 and the electrode 54 form a capacitance.
When a sound wave is incident on the condenser microphone 50, the vibrating film 52 vibrates,
04-05-2019
11
the distance between the vibrating film 52 and the electrode 54 changes, and the electrostatic
capacitance between the vibrating film 52 and the electrode 54 changes.
By outputting this change in capacitance as, for example, a change in voltage, the sound wave
incident on the condenser microphone 50 can be converted into an electric signal.
In the condenser microphone 50, the electrode 54 may have a structure which is not affected by
the sound wave.
For example, the electrode 54 may have a mesh structure.
[0044]
However, the microphone applicable to the present invention is not limited to the condenser type
microphone, and any microphone already known can be applied.
For example, as the first and second microphones 10 and 20, microphones of an electrodynamic
type (dynamic type), an electromagnetic type (magnetic type), a piezoelectric type (crystal type)
or the like may be applied.
[0045]
The first and second microphones 10 and 20 may be silicon microphones (Si microphones) in
which the first and second diaphragms 12 and 22 are made of silicon.
By using a silicon microphone, miniaturization and high performance of the first and second
microphones 10 and 20 can be realized.
At this time, the first and second microphones 10 and 20 may be configured as one integrated
circuit device.
04-05-2019
12
That is, the first and second microphones 10 and 20 may be configured on one semiconductor
substrate.
At this time, the difference signal generation unit 30 described later may also be formed on the
same semiconductor substrate. That is, the first and second microphones 10 and 20 may be
configured as so-called MEMS (Micro Electro Mechanical Systems). However, the first
microphone 10 and the second microphone 20 may be configured as separate silicon
microphones. In addition, as the vibrating film, an inorganic piezoelectric thin film or an organic
piezoelectric thin film may be used to perform acousto-electrical conversion by the piezoelectric
effect.
[0046]
In the microphone system 1 according to the present embodiment, the directions of the first and
second vibrating membranes 12 and 22 are not particularly limited. The first and second
vibrating membranes 12 and 22 may be arranged such that the normals are parallel. At this time,
the first and second vibrating membranes 12 and 22 may be arranged such that the normals do
not become the same straight line. For example, the first and second vibrating membranes 12
and 22 may be spaced apart on the surface of a base (for example, a circuit board) not shown.
Alternatively, the first and second vibrating membranes 12 and 22 may be arranged offset in the
normal direction. However, the first and second vibrating membranes 12 and 22 may be
arranged such that the normals do not become parallel. The first and second vibrating
membranes 12 and 22 may be arranged such that the normals are orthogonal to each other.
[0047]
The microphone system 1 according to the present embodiment has a difference signal
generation unit 30. The difference signal generation unit 30 generates a difference signal
indicating a difference (voltage difference) between the first voltage signal acquired by the first
microphone 10 and the second voltage signal acquired by the second microphone 20. Do. The
function of the difference signal generation unit 30 may be realized by a dedicated hardware
circuit (difference signal generation circuit) or may be realized by signal processing by a CPU or
the like.
04-05-2019
13
[0048]
The microphone system according to the present embodiment may further include a signal
amplification unit that amplifies the differential signal. The differential signal generation unit 30
and the signal amplification unit may be realized by one control circuit. However, the
microphone system 1 according to the present embodiment may have a configuration without
the signal amplification unit inside.
[0049]
FIG. 3 shows an example of a circuit that can realize the differential signal generation unit 30 and
the signal amplification unit. According to the circuit shown in FIG. 3, the first and second voltage
signals are received, and a signal obtained by amplifying the difference signal indicating the
difference by 10 times is output. However, the circuit configuration for realizing the differential
signal generation unit 30 and the signal amplification unit is not limited to this.
[0050]
The microphone system 1 according to the present embodiment may include a housing 40. At
this time, the outer shape of the microphone system may be configured by the housing 40. A
basic posture may be set in the case 40, which makes it possible to regulate the traveling path of
the input voice. The first and second vibrating membranes 12 and 22 may be formed on the
surface of the housing 40. Alternatively, the first and second vibrating membranes 12 and 22
may be disposed inside the housing 40 so as to face the opening (sound collecting port) formed
in the housing 40.
[0051]
FIG. 4 is a diagram for explaining an arrangement method of the microphone system 1 according
to the present embodiment.
[0052]
The reference position 100 is a position set relative to the microphone system based on the
04-05-2019
14
sound source position scheduled by the microphone system 1.
That is, in the present embodiment, it may be considered that the sound source is at the
reference position 100.
[0053]
The straight line 110 is a straight line passing through the positions of the first microphone 10
and the second microphone 20. The position of the microphone may be the position of the sound
pickup port when the microphone has a sound pickup port, or may be the position of the
diaphragm when the microphone does not have a sound pickup port.
[0054]
The perpendicular line 120 is a perpendicular line drawn from the reference position 100 to the
straight line 110.
[0055]
The straight line 130 is a straight line connecting the installation position of the first and second
microphones 10 and 20 and the reference position 100.
The installation positions of the first and second microphones 10 and 20 are, for example, the
position of the first microphone 10, the position of the second microphone 20, the midpoint
between the positions of the first and second microphones 10 and 20, and so on. It may be a
representative point selected from the vicinity of the first and second microphones 10 and 20. In
the present embodiment, the installation positions of the first and second microphones 10 and
20 are taken as the midpoints of the positions of the first and second microphones 10 and 20.
[0056]
θ is the angle between the perpendicular 120 and the straight line 130. The value of θ is the
same value as the angle θ ′ formed by the straight line 130 and the perpendicular 135 passing
04-05-2019
15
through the installation position of the first and second microphones 10 and 20 with respect to
the straight line 110.
[0057]
FIG. 5 is a graph showing an example (measured values) of the directivity characteristics of the
differential microphones having the first and second microphones 10 and 20, which constitute
the microphone system of the present embodiment. The graph of FIG. 5 shows the sound
pressure level detected by the differential microphone as a relative value when the distance from
the sound source to the differential microphone is fixed and the value of θ is changed. The
horizontal axis is the value of θ, and the vertical axis is the sound pressure level. In this
measurement, the sound pressure level may be considered to be proportional to the sensitivity of
the differential microphone. The value of θ is measured from 0 degrees to 180 degrees, and the
frequency of the input voice is measured at six types of 0.3 kHz, 0.5 kHz, 1 kHz, 3 kHz, 5 kHz
and 7 kHz, taking into consideration the human audible band . As in the schematic diagram
shown in FIG. 13B, the sound pressure level reaches its maximum value when the value of θ is
90 degrees, and decreases as it approaches 0 degrees and 180 degrees. Therefore, in order to
collect only target voice using a differential microphone, the arrangement of the differential
microphone with respect to the sound source is important.
[0058]
Therefore, in the microphone system 1, the target sound is collected with high sensitivity by
setting the value of θ such that the sensitivity to the sound from the reference position 100 is a
predetermined ratio or more with respect to the maximum value of the directional
characteristics. be able to.
[0059]
For example, in order to set the sensitivity to the sound from the reference position 100 within
about −6 dB from the maximum value of the sensitivity, the value of θ may be set to 30 degrees
or more and 150 degrees or less.
Further, for example, in order to set the sensitivity to the sound from the reference position 100
within about −3 dB from the maximum value of the sensitivity, the value of θ may be set to 45
degrees or more and 135 degrees or less.
04-05-2019
16
[0060]
In the graph of FIG. 5, the value of θ was from 0 degrees to 180 degrees, but as shown in the
directivity characteristic diagram of FIG. 13B, the directivity characteristics from 180 degrees to
360 degrees are also from 0 degrees Similar to 180 degrees. Therefore, for example, in order to
set the sensitivity to sound from the reference position 100 within about −6 dB from the
maximum value of the sensitivity, the value of θ may be set to 210 degrees or more and 330
degrees or less. Further, for example, in order to set the sensitivity to the sound from the
reference position 100 within about −3 dB from the maximum value of the sensitivity, the value
of θ may be set to 225 degrees or more and 315 degrees or less.
[0061]
Next, the principle of removing sound (noise) other than the target voice will be described. To
eliminate noise, the directivity and distance attenuation characteristics of the differential
microphone are used.
[0062]
As described using the graph of FIG. 5, the sensitivity of the differential microphones becomes
maximum when the value of θ becomes 90 degrees, and becomes smaller as it approaches 0
degrees and 180 degrees. That is, the sensitivity is reduced for noise from a position where the
value of θ is near 0 degrees and near 180 degrees. Therefore, noise from a position where the
value of θ is near 0 degrees and near 180 degrees can be removed by the directivity
characteristics of the differential microphone.
[0063]
In addition, the sound wave attenuates as it travels through the medium, and the sound pressure
(intensity / amplitude of the sound wave) decreases. Since the sound pressure is inversely
proportional to the distance from the sound source, the sound pressure P is related to the
distance R from the sound source as follows:
04-05-2019
17
[0064]
It can be expressed as. In equation (1), K is a proportional constant. FIG. 6 shows a graph
representing the equation (1), but as can be understood from this figure, the sound pressure
(intensity and amplitude of the sound wave) is sharply attenuated at a position close to the sound
source (left side of the graph) It decays gently as you move away from the sound source. In the
microphone system 1 according to the present embodiment, the noise component is removed
using the attenuation characteristic due to this distance.
[0065]
That is, particularly in a close-talking microphone system, the user emits sound from a position
closer to the first and second microphones 10 and 20 (the first and second diaphragms 12 and
22) than the noise source. . Therefore, the voice of the user is greatly attenuated between the
first and second diaphragms 12 and 22, and a difference appears in the strength of the user
voice included in the first and second voltage signals. On the other hand, the noise component
hardly attenuates between the first and second diaphragms 12 and 22 because the sound source
is far from the user's voice. Therefore, it can be considered that no difference appears in the
intensity of the noise contained in the first and second voltage signals. From this, when the
difference between the first and second voltage signals is detected, the noise is eliminated, so
that it is possible to obtain a voltage signal (difference signal) indicating only the voice
component of the user which does not include the noise component it can. That is, the
differential signal can be regarded as a signal indicating the voice of the user from which the
noise component has been removed.
[0066]
Thus, according to the microphone system of the present embodiment, the target voice can be
collected with high sensitivity, and the sound other than the target voice is eliminated by the
directivity and distance attenuation characteristics of the differential microphone. be able to.
[0067]
Also, by arranging the first and second microphones 10 and 20 at a predetermined angle set so
that the sensitivity to sound from the reference position 100 is a predetermined ratio or more
with respect to the maximum value of the directional characteristic, A target voice can be
04-05-2019
18
collected with high sensitivity, and a microphone system can be manufactured in which sounds
other than the target voice can be eliminated by the directivity and distance attenuation
characteristics of the differential microphone.
[0068]
2.
Voice Input Device and Method of Manufacturing the Same First, the configuration of the voice
input device 2 according to the embodiment to which the present invention is applied will be
described with reference to FIGS. 7 to 12.
The voice input device 2 described below can be applied to, for example, voice communication
devices such as a mobile phone, a public phone, a transceiver, and a headset.
[0069]
FIG. 7 is a diagram showing an example of the configuration of the voice input device according
to the embodiment to which the present invention is applied. The voice input device 2 according
to the present embodiment includes a microphone system 1. The microphone system 1 is
configured to include, for example, a first microphone 10, a second microphone 12, and a
difference signal generation unit 30, as shown in FIG. The detailed embodiment of the
microphone system 1 is as described above with reference to FIGS. 1 to 6, and thus the
description thereof will not be repeated.
[0070]
Voice input device 2 according to the present embodiment includes a speaker 150. The speaker
150 is configured by a known / known speaker, and may be, for example, a speaker used for
voice communication devices such as a mobile phone, a public phone, a transceiver, and a
headset.
04-05-2019
19
[0071]
The voice input device 2 according to the present embodiment may include the housing 3. At this
time, the outer shape of the voice input device 2 may be configured by the housing 3. The first
microphone 10 and the second microphone 12 may be formed on the surface of the housing 3.
Alternatively, the first microphone 10 and the second microphone 12 may be disposed inside the
housing 3 so as to face the opening (sound collecting port) formed in the surface of the housing
3. Similarly, the speaker 150 may be formed on the surface of the housing 3 or may be disposed
inside the housing 3 so as to face the opening formed on the surface of the housing 3.
[0072]
The housing 3 is an optional form including the microphone system 1 and the speaker 150. A
mobile phone will be described using FIG. 8 to FIG. 10 as an example. The housing 3 may have a
form integrally having no movable portion as shown in FIG. In addition, the housing 3 may
include a folding unit 300 as shown in FIG. 9, and the external shape of the entire housing may
be changed. Furthermore, as shown in FIG. 10, the housing 3 may include a flipper portion 400,
and the external shape of a part of the housing may be changed.
[0073]
FIG. 11 is a diagram for explaining the positional relationship between the speaker 150 and the
head 200 of the speaker. The same reference numerals as in FIGS. 4 and 7 denote the same parts
in FIG.
[0074]
The microphone system 1, the speaker 150, and the housing 3 are as described above with
reference to FIG.
[0075]
The arrangement of the speaker's head 200 including the voice input device 2 and the ear 210
and the mouth 220 is relatively determined in relation to the speaker 150 depending on the use
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form of the voice input device 2.
For example, when the voice input device 2 is a mobile phone, it is assumed that the speaker 150
and the ear 210 are placed close to each other during a call. Also, the arrangement of the ears
210 and the mouth 220 can be estimated in consideration of the size of a standard human face.
For example, at the time of standing up, the height difference h between the ear 210 and the
mouth 220 is about 100 mm to 150 mm.
[0076]
Therefore, the sound source position scheduled by the voice input device 2, that is, the position
of the mouth 220 can be set relative to the voice input device 2 based on the position of the
speaker 150. In the present embodiment, the position set relative to the voice input device 2
based on the position of the speaker 150 is used as the reference position 100.
[0077]
The straight line 110 is a straight line passing through the positions of the first microphone 10
and the second microphone 20. The position of the microphone may be the position of the sound
pickup port when the microphone has a sound pickup port, or may be the position of the
diaphragm when the microphone does not have a sound pickup port.
[0078]
The perpendicular line 120 is a perpendicular line drawn from the reference position 100 to the
straight line 110.
[0079]
The straight line 130 is a straight line connecting the installation position of the first and second
microphones 10 and 20 and the reference position 100.
The installation positions of the first and second microphones 10 and 20 are, for example, the
04-05-2019
21
position of the first microphone 10, the position of the second microphone 20, the midpoint
between the positions of the first and second microphones 10 and 20, and so on. It may be a
representative point selected from the vicinity of the first and second microphones 10 and 20. In
the present embodiment, the installation positions of the first and second microphones 10 and
20 are taken as the midpoints of the positions of the first and second microphones 10 and 20.
[0080]
θ is the angle between the perpendicular 120 and the straight line 130.
[0081]
An example (actually measured value) of the directivity characteristic of the differential
microphone having the first and second microphones 10 and 20 constituting the microphone
system of the present embodiment is as shown in the graph of FIG. In order to collect only the
target voice using, placement of a differential microphone to the sound source is important.
[0082]
Therefore, by setting the value of θ in the voice input device 2 so that the sensitivity to the
sound from the reference position 100 is a predetermined ratio or more with respect to the
maximum value of the directional characteristic, the target voice is collected with high sensitivity.
can do.
[0083]
For example, in order to set the sensitivity to the sound from the reference position 100 within
about −6 dB from the maximum value of the sensitivity, the value of θ may be set to 30 degrees
or more and 150 degrees or less.
Further, for example, in order to set the sensitivity to the sound from the reference position 100
within about −3 dB from the maximum value of the sensitivity, the value of θ may be set to 45
degrees or more and 135 degrees or less.
[0084]
04-05-2019
22
In the graph of FIG. 5, the value of θ was from 0 degrees to 180 degrees, but as shown in the
directivity characteristic diagram of FIG. 13B, the directivity characteristics from 180 degrees to
360 degrees are also from 0 degrees Similar to 180 degrees.
Therefore, for example, in order to set the sensitivity to sound from the reference position 100
within about −6 dB from the maximum value of the sensitivity, the value of θ may be set to 210
degrees or more and 330 degrees or less.
Further, for example, in order to set the sensitivity to the sound from the reference position 100
within about −3 dB from the maximum value of the sensitivity, the value of θ may be set to 225
degrees or more and 315 degrees or less.
[0085]
FIG. 12 is a diagram for explaining the arrangement of the voice input device 2 according to the
present embodiment when the sound source position scheduled by the microphone system 1,
that is, the reference position has a certain range. As described above, for example, when the
voice input device 2 is a mobile phone, it is assumed that the speaker 150 and the ear 210 are
placed close to each other during a call. Also, the arrangement of the ears 210 and the mouth
220 can be estimated in consideration of the size of a standard human face. For example, at the
time of standing up, the height difference h between the ear 210 and the mouth 220 is about
100 mm to 150 mm. Therefore, there is also a significance that the sound source position
scheduled by the microphone system 1, that is, the reference position has a certain range (about
50 mm in the above example).
[0086]
The positional relationship between the head 200, the ears 210, and the mouth 220 of the
speaker shown in FIG. 11 is common to FIGS. 11 and 12, and therefore the description thereof is
omitted in FIG. Further, in order to simplify the explanatory drawing, the description of the
housing 3 is also omitted in FIG.
[0087]
The case where the reference position has a reference position range 103 from the first
04-05-2019
23
reference position 101 closest to the speaker 150 to the second reference position 102 farthest
to the speaker 150 will be described using FIG. 12.
[0088]
The straight line 110 is a straight line passing through the positions of the first microphone 10
and the second microphone 20.
The position of the microphone may be the position of the sound pickup port when the
microphone has a sound pickup port, or may be the position of the diaphragm when the
microphone does not have a sound pickup port.
[0089]
The perpendicular line 121 is a first perpendicular line drawn from the first reference position
101 to the straight line 110, and the foot of the perpendicular line 121 is set as the first
boundary position 161.
[0090]
The perpendicular line 122 is a second perpendicular line drawn from the second reference
position 102 to the straight line 110, and the foot of the perpendicular line 122 is set as the
second boundary position 162.
[0091]
A straight line 131 is a straight line connecting the installation position 191 of the first and
second microphones 10 and 20 and the first reference position 101 when the microphone
system is disposed at the position 1-1.
The straight line 132 is a straight line connecting the installation position 192 of the first and
second microphones 10 and 20 and the first reference position 101 when the microphone
system is disposed at the position 1-2.
04-05-2019
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The straight line 133 is a straight line connecting the installation position 193 of the first and
second microphones 10 and 20 and the second reference position 102 when the microphone
system is disposed at the position of 1-3. The straight line 134 is a straight line connecting the
installation position 194 of the first and second microphones 10 and 20 and the second
reference position 102 when the microphone system is disposed at the position 1-4. The
installation positions of the first and second microphones 10 and 20 are, for example, the
position of the first microphone 10, the position of the second microphone 20, the midpoint
between the positions of the first and second microphones 10 and 20, and so on. It may be a
representative point selected from the vicinity of the first and second microphones 10 and 20. In
the present embodiment, the installation positions of the first and second microphones 10 and
20 are taken as the midpoints of the positions of the first and second microphones 10 and 20.
[0092]
θ 1-1 is the angle between the first perpendicular 121 and the straight line 131. θ 1-2 is the
angle between the first perpendicular 121 and the straight line 132. θ2-1 is an angle formed by
the second perpendicular line 122 and the straight line 133. θ2-2 is an angle between the
second perpendicular line 122 and the straight line 134.
[0093]
An example (measured value) of the directivity characteristic of the differential microphone
having the first and second microphones 10 and 20 constituting the microphone system of the
present embodiment is as shown in FIG. In order to use it and collect only the target voice,
placement of a differential microphone to the sound source is important.
[0094]
Therefore, first, in the voice input device 2, the first and second values when θ1-1 is set such
that the sensitivity to the sound from the first reference position 101 is less than a
predetermined ratio with respect to the maximum value of the directional characteristics. The
arrangement position of the two microphones 10 and 20 is taken as the position of the
arrangement position 191.
Further, in the voice input device 2, the first and second values when θ1-2 is set such that the
sensitivity to the sound from the first reference position 101 is less than a predetermined ratio
04-05-2019
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with respect to the maximum value of the directional characteristics The arrangement position of
the microphones 10 and 20 is set as the arrangement position 192. Furthermore, in the voice
input device 2, the first and second values when the value of .theta..sub.2-1 is set such that the
sensitivity to the sound from the second reference position 102 is less than a predetermined
ratio with respect to the maximum value of the directional characteristics. The arrangement
position of the microphones 10 and 20 is set as the arrangement position 193. Then, in the voice
input device 2, the first and second values when the value of θ2-2 is set such that the sensitivity
to the sound from the second reference position 102 is less than a predetermined ratio with
respect to the maximum value of the directional characteristic The arrangement position of the
microphones 10 and 20 is set as the position of the arrangement position 194.
[0095]
At this time, first, in the range from the arrangement position 191 to the arrangement position
192, the sensitivity to the sound from the first reference position 101 with respect to the
maximum value of the directional characteristic when the first and second microphones 10 and
20 are arranged. It is a position range which becomes less than a predetermined ratio. This range
is referred to as a first prohibited range 171.
[0096]
Further, in the range from the arrangement position 193 to the arrangement position 194, when
the first and second microphones 10 and 20 are arranged, the sensitivity to the sound from the
second reference position 102 is a predetermined ratio to the maximum value of the directivity
characteristic. It is a position range which becomes less than. This range is referred to as a
second prohibited range 172.
[0097]
Furthermore, the range of the first boundary position 161 to the second boundary position 162
arranges the first and second microphones 10 and 20 when the reference position, that is, the
position of the sound source is in the range of the reference position range 103. In this case, the
perpendicular line drawn from the reference position to a straight line passing the positions of
the first and second microphones and the straight line connecting the installation position of the
first and second microphones to the reference position is 0 degree. It is a range to get. This range
04-05-2019
26
is referred to as a third prohibited range 173.
[0098]
Therefore, the sensitivity to the sound from the reference position existing in the range of the
reference position range 103 is made to be a predetermined ratio or more with respect to the
maximum value of the directional characteristics by arranging in other than the first to third
prohibited ranges 171 to 173. be able to. That is, the target voice can be collected with high
sensitivity.
[0099]
For example, in order to set the sensitivity to the sound from the reference position within about
-6 dB from the maximum value of the sensitivity, the values of θ1-1 to θ2-2 may be set to 30
degrees or more and 150 degrees or less. Further, for example, in order to set the sensitivity to
the sound from the reference position within about −3 dB from the maximum value of the
sensitivity, the values of θ1-1 to θ2-2 may be set to 45 degrees or more and 135 degrees or
less.
[0100]
As shown in the directivity characteristic diagram of FIG. 13B, the directivity characteristics from
180 degrees to 360 degrees are also the same as 0 degrees to 180 degrees. Therefore, for
example, in order to set the sensitivity to sound from the reference position within about -6 dB
from the maximum value of the sensitivity, the values of θ1-1 to θ2-2 may be set to 210
degrees or more and 330 degrees or less. Further, for example, in order to set the sensitivity to
the sound from the reference position within about −3 dB from the maximum value of the
sensitivity, the values of θ1-1 to θ2-2 may be set to 225 degrees or more and 315 degrees or
less.
[0101]
The reference position range 103 may be, for example, about 50 mm in consideration of the
04-05-2019
27
difference in height between the ear 210 and the mouth 220 being about 100 mm to 150 mm
when standing up. Furthermore, for example, in a normal usage form of a voice input device such
as a mobile phone, the distance from the sound source (mouth) to the first and second
microphones, that is, the length of the straight lines 131 to 134 may be about 50 mm.
[0102]
In this case, for example, in order to set the sensitivity to sound from the reference position
within about -6 dB from the maximum value of the sensitivity, the distance SM1 between the
speaker 150 and the arrangement position 191 is set to a value of .theta.
[0103]
となる。
Similarly, the distance SM2 between the speaker 150 and the arrangement position 194 is set to
a value of θ2-2 as 30 degrees.
[0104]
となる。
[0105]
Therefore, by setting the distance between the speaker 150 and the installation position of the
first and second microphones to 0 mm or more and 75 mm or less or 175 mm or more, the
sensitivity to the speaker's voice is within about -6 dB from the maximum It can be a voice input
device.
[0106]
Also, for example, in order to set the sensitivity to the sound from the reference position within
about -3 dB from the maximum value of the sensitivity, the distance SM1 between the speaker
150 and the arrangement position 191 is 45.degree.
[0107]
04-05-2019
28
となる。
Similarly, the distance SM2 between the speaker 150 and the arrangement position 194 is 45
degrees, with the value of .theta.
[0108]
となる。
[0109]
Therefore, by setting the distance between the speaker 150 and the installation position of the
first and second microphones to 0 mm or more and 64.6 mm or less or 185.4 mm or more, the
sensitivity to the speaker's voice is approximately-from the maximum value of the sensitivity. An
audio input device can be made within 3 dB.
[0110]
Next, the principle of removing sound (noise) other than the target voice will be described.
To eliminate noise, the directivity and distance attenuation characteristics of the differential
microphone are used.
[0111]
As described using the graph of FIG. 5, the sensitivity of the differential microphones becomes
maximum when the value of θ becomes 90 degrees, and becomes smaller as it approaches 0
degrees and 180 degrees.
That is, the sensitivity is reduced for noise from a position where the value of θ is near 0
degrees and near 180 degrees.
04-05-2019
29
Therefore, noise from a position where the value of θ is near 0 degrees and near 180 degrees
can be removed by the directivity characteristics of the differential microphone.
In particular, for example, in a voice communication device such as a cellular phone, a public
phone, a transceiver, a headset, etc., from a sound source farther from the voice input device 2
than the speaker at the same height as the head 200 of the speaker. It is known that there are
many noises, such as the speech of others. That is, there is much noise near 0 degrees or near
180 degrees in the directivity shown in FIG. Therefore, noise can be removed by the directivity of
the differential microphone.
[0112]
Also, as described using FIG. 6 and equation (1), the sound pressure (intensity / amplitude of
sound wave) attenuates rapidly at a position close to the sound source (left side of the graph),
and gradually attenuates away from the sound source . In the voice input device 2 according to
the present embodiment, the noise component is removed using the attenuation characteristic
due to this distance.
[0113]
That is, particularly in the close-talking type voice input device, the user can make voice from a
position closer to the first and second microphones 10 and 20 (the first and second diaphragms
12 and 22) than the noise source. It emits. Therefore, the voice of the user is greatly attenuated
between the first and second diaphragms 12 and 22, and a difference appears in the strength of
the user voice included in the first and second voltage signals. On the other hand, the noise
component hardly attenuates between the first and second diaphragms 12 and 22 because the
sound source is far from the user's voice. Therefore, it can be considered that no difference
appears in the intensity of the noise contained in the first and second voltage signals. From this,
when the difference between the first and second voltage signals is detected, the noise is
eliminated, so that it is possible to obtain a voltage signal (difference signal) indicating only the
voice component of the user which does not include the noise component it can. That is, the
differential signal can be regarded as a signal indicating the voice of the user from which the
noise component has been removed.
[0114]
04-05-2019
30
As described above, according to the voice input device of this embodiment, the target voice can
be collected with high sensitivity, and the sound other than the target voice is eliminated by the
directivity and distance attenuation characteristics of the differential microphone. can do.
[0115]
Also, by arranging the first and second microphones 10 and 20 at a predetermined angle set so
that the sensitivity to sound from the reference position 100 is a predetermined ratio or more
with respect to the maximum value of the directional characteristic, A voice of interest can be
collected with high sensitivity, and a voice input device can be manufactured that can remove
sounds other than voice of interest by attenuation characteristics due to the directivity and
distance of the differential microphone.
[0116]
The figure for demonstrating a microphone system.
The figure for demonstrating a microphone system.
The figure for demonstrating a microphone system. The figure for demonstrating a microphone
system. The figure for demonstrating a microphone system. The figure for demonstrating a
microphone system. The figure for demonstrating a speech input device. The figure for
demonstrating a speech input device. The figure for demonstrating a speech input device. The
figure for demonstrating a speech input device. The figure for demonstrating a speech input
device. The figure for demonstrating a speech input device. The figure for demonstrating the
directional characteristic of a differential microphone. The figure for demonstrating the
directional characteristic of a differential microphone.
Explanation of sign
[0117]
Reference Signs List 1 microphone system, 2 voice input device, 3 housing, 10 first microphone,
12 first diaphragm, 20 second microphone, 22 second diaphragm, 30 differential signal
generator, 40 housing, 50 Condenser type microphone, 52 diaphragms, 54 electrodes, 100
reference position, 101 first reference position, 102 second reference position, 103 reference
04-05-2019
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position range, 110 straight lines, 120 normals, 121 first normals, 122 second Perpendicular,
130 to 134 straight, 135 perpendicular, θ angle, θ ′ angle, θ1-1 angle, θ1-2 angle, θ2-1
angle, θ2-2 angle, 150 speaker, 161 first boundary position, 162 second Boundary position,
171 first prohibited area, 172 second prohibited area, 173 third prohibited area, 191-194
arrangement position, 200 talker's head, 210 ears, 220 mouths, 00 fold, 400 flipper, 900 area,
910 area
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