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JP2016032139

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DESCRIPTION JP2016032139
PROBLEM TO BE SOLVED: To output an audio signal with little noise even under an environment
where noise is generated. SOLUTION: A single directional first microphone (10) and a single (1)
whose directional axis is substantially in the same direction as the directional axis of the first
microphone (10) and are arranged axially back and forth with the first microphone (10) Based on
the detection results of the directional second microphone 20, the noise detection unit 30 that
detects noise included in the output signal of the first microphone 10, and the noise detection
unit 30, the first microphone 10 and the second microphone 20 And a control unit 40 that
controls the output. [Selected figure] Figure 7
Microphone device
[0001]
The present invention relates to a microphone device.
[0002]
A composite microphone device is known in which a plurality of microphones are mounted in
one microphone case.
In many complex microphone devices, two microphones are built in one microphone case.
Among the composite microphone devices, one in which two microphones are built in one
microphone case is also called a double microphone.
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[0003]
The composite microphone device can output an audio signal from any of a plurality of
microphones. Therefore, even when one of the plurality of microphones can not be used due to a
failure or the like, the composite microphone device can be switched to output signals from other
microphones and used.
[0004]
In a composite microphone device used in a podium or the like, a single directivity electret
condenser microphone is often used. The electret condenser microphone can prevent howling
and the like even when a plurality of microphones are provided close to each other. In addition,
the electret condenser microphone does not require a power supply for generating a polarization
voltage.
[0005]
In the composite microphone device having a structure in which a plurality of microphones are
arranged in the width direction, although the difference in sound quality of the plurality of
microphones does not easily occur, the outer size of the case becomes large according to the
number of microphones mounted.
[0006]
In the composite microphone device having a structure in which a plurality of unidirectional
microphones are arranged in a line on the directional axis of the composite microphone device,
the outer size of the case can be reduced.
[0007]
By the way, a unidirectional condenser microphone is likely to generate noise due to air flow
such as wind noise of an air conditioner or the like (pop noise due to air flow such as a popping
sound of a speaker).
[0008]
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In a composite microphone device in which unidirectional microphones are mounted in a row in
the length direction on the directional axis, the microphone mounted in the front (speaker's
direction) is used as a main microphone because it is easy to pick up the voice of the speaker ing.
However, the microphone mounted on the front is also likely to pick up noise due to the air flow
described above.
[0009]
For this reason, in the conventional composite microphone device, there is a problem that when
the front microphone picks up noise, it is not possible to output an audio signal with little noise.
[0010]
It is switched whether to use the output signal of one of the two nondirectional microphones as
the output signal or to use the output signal of one of the microphones plus the negative phase
signal of the other microphone as the output signal. A technology is disclosed (see, for example,
Patent Document 1).
[0011]
In the technology disclosed in Patent Document 1, when the ambient noise is low, the negative
phase signal of the other microphone is added to the output signal of one of the microphones to
output a signal with strong directivity.
Further, in the technology disclosed in Patent Document 1, when the ambient noise is high, only
the output signal of one of the microphones is output.
[0012]
In the technique disclosed in Patent Document 1, when high noise occurs near one of the
microphones, the noise is likely to be picked up.
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Therefore, even with the technique disclosed in Patent Document 1, there is a problem that an
audio signal with little noise can not be output.
[0013]
JP-A-9-149490
[0014]
An object of the present invention is to provide a microphone device capable of outputting an
audio signal with less noise even in a noisy environment.
[0015]
According to the present invention, there is provided a unidirectional single microphone, wherein
the directional axis is substantially in the same direction as the directional axis of the first
microphone, and the unidirectional microphone is disposed in front and back in the axial
direction with the first microphone. A second microphone, a noise detection unit that detects
noise contained in an output signal of the first microphone, and a control unit that controls the
outputs of the first microphone and the second microphone based on the detection result of the
noise detection unit; It is characterized by having.
[0016]
According to the present invention, it is possible to output an audio signal with less noise even in
an environment where noise is generated.
[0017]
It is a fragmentary sectional view showing an embodiment of a microphone device concerning
the present invention.
It is an expanded sectional view of the microphone case of the microphone apparatus of FIG.
It is a graph which shows the directional characteristic of the 1st microphone of the microphone
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apparatus of FIG.
It is a graph which shows the directional characteristic of the 2nd microphone of the microphone
apparatus of FIG.
It is a graph which shows the directional frequency characteristic of the 1st microphone of the
microphone apparatus of FIG.
It is a graph which shows the directional frequency characteristic of the 2nd microphone of the
microphone apparatus of FIG.
It is a circuit diagram of the microphone apparatus of FIG. FIG. 6 is a circuit diagram showing
another embodiment of the microphone device according to the present invention.
[0018]
Microphone Device (1) Hereinafter, an embodiment of a microphone device according to the
present invention will be described with reference to the drawings.
[0019]
FIG. 1 is a partial cross-sectional view showing an embodiment of a microphone device according
to the present invention.
FIG. 1 shows a gooseneck double microphone as an example of the microphone device according
to the present embodiment. As shown to the same figure, the microphone apparatus 1 has the
microphone case 2 which accommodates the 1st microphone 10, the 2nd microphone 20 grade |
etc.,.
[0020]
The microphone device 1 further includes a support pipe 3 for supporting the microphone case
2, a flexible pipe 4 for supporting the support pipe 3, and a base casing 5 for supporting the
flexible pipe 4 having an output connector (not shown) and the like. Have.
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[0021]
FIG. 2 is an enlarged cross-sectional view of the microphone case 2 of the microphone device 1.
As shown in the figure, the microphone case 2 has an opening at both ends, and has a cylindrical
shape having an inside diameter and a length capable of housing the first microphone 10 and the
second microphone 20 inside.
[0022]
The microphone case 2 has an opening 6 and an opening 7 for collecting sound from the outside
in a peripheral wall portion corresponding to the sound collecting unit 11 of the first microphone
10 and the sound collecting unit 21 of the second microphone 20.
[0023]
A tail piece 8 is attached to the open end of the microphone case 2 on the support pipe 3 side so
as to close the open end.
Further, a cap 9 covering the opening end is attached to the opening end of the microphone case
2 on the opposite side (tip side) to the side on which the tail piece 8 is attached. The cap 9 is
provided with an opening for collecting sound from the tip side of the microphone device 1.
[0024]
The first microphone 10 is housed near the tip in the microphone case 2 so that the sound
collecting unit 11 is positioned near the opening 6 as described above. In addition, the second
microphone 20 is accommodated closer to the tailpiece 8 in the microphone case 2 so that the
sound collection unit 21 is positioned near the opening 7 as described above. The first
microphone 10 and the second microphone 20 are disposed longitudinally in the axial direction
of the microphone case 2.
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[0025]
The first microphone 10 and the second microphone 20 are unidirectional directivity electret
condenser microphones. The first microphone 10 and the second microphone 20 may have
substantially the same directional axes, for example, the directional axes may be coaxial. In the
present embodiment, the direction of the cap 9 of the microphone case 2 is the pointing axis.
That is, in the microphone device 1, the direction of the cap 9 (tip direction) of the microphone
case 2 is the pointing axis.
[0026]
In the microphone device according to the present invention, three or more microphones having
substantially the same directional axes may be provided.
[0027]
In the microphone device 1, the first microphone 10 is disposed closer to the tip of the
microphone case 2, and a cap 9 having an opening on the tip side of the microphone case 2 is
provided.
[0028]
FIG. 3 is a graph showing the directivity characteristic of the first microphone 10 of the
microphone device 1.
FIG. 4 is a graph showing the directivity characteristic of the second microphone 20 of the
microphone device 1.
According to FIGS. 3 and 4, it can be seen that the directivity of the first microphone 10 provided
closer to the tip of the microphone case 2 in the direction of the tip of the microphone device 1 is
stronger.
[0029]
That is, in the microphone device 1, the first microphone 10 can easily acquire the voice of the
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speaker located in the tip direction than the second microphone 20.
[0030]
FIG. 5 is a graph showing directional frequency characteristics of the first microphone 10 of the
microphone device 1.
FIG. 6 is a graph showing the directional frequency characteristics of the second microphone 20
of the microphone device 1. According to FIG. 5 and FIG. 6, the first microphone 10 and the
second microphone 20 both output 90 degrees, 180 degrees, and 120 degrees while there is
almost no change in the output level of 0 degrees shown by thick solid lines. You can see that the
level is down.
[0031]
The first microphone 10 accommodates a circuit board 12 that constitutes an electric circuit of
the first microphone 10. Further, the second microphone 20 accommodates a circuit board 22
that constitutes an electric circuit of the second microphone 20.
[0032]
FIG. 7 is a circuit diagram of the microphone device 1 of FIG. As shown in the figure, the
microphone device 1 is provided with a low pass filter (low pass filter) 30 for passing only an
audio signal (low frequency audio signal) in a predetermined range from an audio signal acquired
by the first microphone 10. It is done.
[0033]
The low pass filter 30 functions as a noise detection unit that detects an audio component
corresponding to noise included in the output signal of the first microphone. Here, since the first
microphone 10 is located near the speaker as described above, it easily picks up a noise
component due to air flow such as wind noise and pop noise, and functions as a noise detection
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sensor.
[0034]
The microphone device 1 is provided with a switch driver 40 that switches the switch SW1 based
on the detection result of the low pass filter 30, that is, the detected low frequency audio signal.
[0035]
The switch driver 40 compares the low pass audio signal level passed through the low pass filter
30 with a predetermined cutoff signal level.
Here, the predetermined cutoff signal level is a noise component (for example, a frequency of
about 100 Hz) limit level (threshold) such as wind noise and pop noise acquired from the first
microphone 10, and the switch driver 40 It is stored in a storage unit (not shown).
[0036]
As a result of comparison between the cutoff signal level and the low-pass audio signal level, the
switch driver 40 determines which one of the first microphone 10 and the second microphone
20 is to output the audio signal.
[0037]
In addition, the microphone device 1 is provided with a switch SW1 that switches the output
from the first microphone 10 and the output from the second microphone 20 based on the
comparison result of the cutoff signal level and the low-pass audio signal level. There is.
[0038]
The switch SW1 corresponds to a control unit, switches the output signal from the first
microphone 10 and the output signal from the second microphone 20, and outputs only the
signal from one of the microphones.
[0039]
The output of the first microphone 10 and the output of the second microphone 20 can be
switched by the switch driver 40 by using, for example, a digital switch that can perform switch
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operation electronically as the switch SW1.
[0040]
Further, the microphone device 1 is provided with a switch SW2 for the user to switch the output
of the first microphone 10 and the second microphone 20.
The switch SW2 is used, for example, to select one of the microphones that operate normally
when any one of the first microphone 10 and the second microphone 20 is unusable due to a
failure.
[0041]
In the microphone device 1, the outputs of the first microphone 10 and the second microphone
20 can be switched by the switch SW 1 based on the result of detection of noise based on the
low-pass audio signal detected by the low-pass filter 30.
[0042]
Therefore, according to the microphone device 1, when the noise is small, it is possible to output
a voice with good sound quality from the voice signal of the first microphone 10 close to the
mouth of the speaker.
Further, according to the microphone device 1, when noise is large, voice with less noise can be
output using the voice signal from the second microphone 20 far from the speaker's mouth.
[0043]
In particular, according to the microphone device according to the present embodiment, even
when noise or the like caused by air flow such as wind noise or pop noise is generated, voice with
less noise can be output.
[0044]
Microphone Device (2) Next, another embodiment of the microphone device according to the
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present invention will be described only with respect to differences from the embodiments
described above.
[0045]
FIG. 8 is a circuit diagram showing another embodiment of the microphone device according to
the present invention.
As shown in the figure, the microphone device 100 according to the present embodiment
includes a digital volume (electronic volume including a semiconductor) VR controlled by the
volume driver 50.
The digital volume VR is an alternative to the switch SW2 of the microphone device 1 described
above, and this point is different from the microphone device 1 described above.
[0046]
The digital volume VR changes the ratio of the outputs of the first microphone 10 and the second
microphone 20 stepwise or steplessly from the output of only the first microphone 10 to the
output of only the second microphone 20. Can.
That is, the digital volume VR mixes the outputs of the first microphone 10 and the second
microphone 20 and outputs the outputs of the first microphone 10 and the second microphone
20, or outputs the output of the second microphone 20, or The function of outputting only the
microphone 20 is provided.
[0047]
The digital volume VR is controlled by the volume driver 50 as described above.
An output signal of the microphone device 100 is output from a terminal corresponding to a
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variable output terminal of the digital volume VR.
[0048]
The volume driver 50 is a substitute for the switch driver 40 described above, and controls the
digital volume VR in accordance with the low-pass audio signal level output from the low pass
filter 30.
[0049]
Therefore, the microphone device 100 can control the ratio of the outputs of the first
microphone 10 and the second microphone 20 based on the low-pass audio signal level from the
first microphone 10.
[0050]
Unlike the microphone device 1 described above, the microphone device 100 can output an
audio signal of the microphone device 100 by mixing the output of the first microphone 10 and
the output of the second microphone 20.
[0051]
Effects of the Embodiment As described above, according to the microphone device of the
present embodiment, the following effects can be obtained.
[0052]
In the microphone device according to the present embodiment, noise is detected from the audio
signal of the first microphone to control the output of the first microphone and the second
microphone.
Therefore, according to the microphone device according to the present embodiment, it is
possible to output an audio signal with little noise even under an environment where noise is
generated.
[0053]
Further, according to the microphone device according to the present embodiment, even when
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noise or the like caused by an air flow such as wind noise or pop noise is generated, it is possible
to output voice with less noise.
[0054]
Further, according to the microphone device according to the present embodiment, the ratio of
the outputs of the first microphone 10 and the second microphone 20 (the mixing ratio of the
audio signal) according to the presence or absence and the size of the noise is a state in which
the noise Can be adjusted.
[0055]
Reference Signs List 1 microphone device 2 microphone case 3 support pipe 4 flexible pipe 5
base housing 6 opening 7 opening 8 tail piece 9 cap 10 first microphone 11 sound collecting
unit 12 circuit board 20 second microphone 21 sound collecting unit 22 circuit board 30 low
pass Pass filter 40 Switch driver 50 Volume driver 100 Microphone device SW1 switch SW2
switch VR Digital volume
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