JPH1169481

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DESCRIPTION JPH1169481
[0001]
BACKGROUND OF THE INVENTION The present invention is a variable-mode variable
microphone capable of reducing the influence of noise and vibration from the inside of a device
by changing the directivity of the microphone by providing a nondirectional microphone, phase
shift means, and addition means. The present invention relates to a directional microphone
device, and more particularly to a variable directional microphone device incorporated in a video
integrated camera.
[0002]
2. Description of the Related Art With the miniaturization of video integrated cameras, the
microphone device incorporated therein becomes a shape that is placed near the noise and
vibration source generated from within the main body, and the influence from the noise and
vibration source is It is getting stronger. In order to cope with such a problem, there are various
variable directional microphone devices in which the directivity of the microphone incorporated
in the device is controlled to reduce the influence from noise and vibration in the device.
[0003]
As a conventional variable directional microphone device, for example, there is a variable
directional microphone disclosed in Japanese Patent Publication No. 60-1994. FIG. 6 shows a
schematic configuration of the variable directional microphone and FIG. 7 shows a variable
directional microphone. A directional pattern figure is shown.
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[0004]
In FIG. 6, the variable directional microphone 30 includes a unidirectional microphone 33a, a
unidirectional microphone 33b, a phase shift circuit 34, an adder 35, and an equalizer 36.
[0005]
The unidirectional microphone 33a and the unidirectional microphone 33b are disposed forward
on the axis 40 with respect to the sound source 32, and the output of the unidirectional
microphone 33a is added to the phase shifter 34, and the unidirectional microphone The output
of 33b is applied to an adder 35.
The phase shifter 34 adds to the adder 35 an output obtained by phase-shifting the output from
the unidirectional microphone 33 a in the range of 0 ° to 180 °.
[0006]
The adder 35 adds an output obtained by adding the output from the phase shifter 34 and the
output of the unidirectional microphone 33 b to the equalizer 36.
The equalizer 36 applies an output obtained by performing frequency correction so that the
frequency characteristic of the output of the adder 35 is substantially flat, to the terminal T 39 as
an output of the variable directional microphone 30.
[0007]
FIG. 7 shows a directivity pattern of the variable directional microphone 30. As shown in FIG. In
FIG. 7, the angle θ of the incoming sound wave from the sound source 32 to the unidirectional
microphone 33a and the unidirectional microphone 33b with respect to the axis 40 is scaled
clockwise, and the frequency of the sound source 32 (100 Hz, 500 Hz, 1 KHz, 2 KHz 6 shows the
directivity pattern of the variable directional microphone 30 in the case of FIG.
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[0008]
From the directivity pattern diagram shown in FIG. 7, the variable directional microphone 30 is a
device disposed with the sound sensitivity in the direction of zero degree of the angle θ of the
incoming sound wave increased and the sound sensitivity for the other angles θ reduced. It is
said that the noise from the inside and the influence from the vibration source can be reduced.
[0009]
However, when the variable directional microphone disclosed in Japanese Examined Patent
Publication No. 60-1994 is mounted on a video integrated camera, the voice direction of the
camera operator is 180 °. The lack of audio sensitivity causes problems such as the operator's
inability to collect audio.
[0010]
In addition, since the variable directional microphone disclosed in Japanese Patent Publication
No. 60-1994 uses a unidirectional microphone, the unidirectional microphone itself is different
from the nondirectional microphone in vibration and As it is susceptible to wind noise, it is
susceptible to vibrations from the inside of the apparatus and vibrations from the operator's
hand, and is not suitable for use outdoors with wind.
[0011]
The present invention has been made to solve the problems of the prior art described above, and
its object is to provide a plurality of nondirectional microphones, and phase shifting means for
shifting the output from the nondirectional microphones. , Adding means for adding the output
of the nondirectional microphone and the output of the phase shift means, and changing the
directivity of the microphone to reduce the influence of the vibration from inside the device and
the vibration and wind due to the hand movement of the operator An object of the present
invention is to provide a variable directional microphone device capable of picking up a target
sound.
[0012]
SUMMARY OF THE INVENTION In order to solve the above problems, a variable directional
microphone device according to the present invention comprises at least one nondirectional
microphone among a plurality of nondirectional microphones and a plurality of nondirectional
microphones. Phase shift means for varying the output phase from the dynamic microphone in
the range of 0 ° to 180 °, and the output and shift of at least one nondirectional microphone
other than the nondirectional microphone whose output phase is varied by the phase shift means
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And adding means for adding the output of the phase means and the output of the phase means.
[0013]
The variable directional microphone device according to the present invention includes the
plurality of nondirectional microphones, the phase shift means, and the addition means, so that
the directivity of the microphone can be varied.
[0014]
Embodiments of the present invention will be described below with reference to the attached
drawings.
FIG. 1 is a schematic block diagram of a variable directional microphone device according to the
present invention.
In FIG. 1, the variable directional microphone device 1 includes a nondirectional microphone 3a,
a nondirectional microphone 3b, phase shift means 4, an addition means 5 and an equalizer 6.
Here, it is characterized in that non-directional microphones 3a and 3b are used in place of the
conventional unidirectional microphones 33a and 33b.
[0015]
A non-directional microphone 3a and a non-directional microphone 3b are disposed on the axis
8, and the non-directional microphone 3a and the non-directional microphone 3b are disposed at
an interval of a distance D.
The nondirectional microphone 3a picks up the incoming voice Sa from the sound source 2 and
converts it into an electric signal to output a microphone signal S3a obtained to the phase shift
means 4.
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The nondirectional microphone 3 b picks up the incoming sound Sb from the sound source 2 and
converts it into an electric signal to output a microphone signal S 3 b obtained to the adding
means 5.
[0016]
The phase shift means 4 outputs, to the addition means 5, a phase signal S4 obtained by phaseshifting the phase of the microphone signal S3a from the nondirectional microphone 3a in the
range of 0 ° to 180 °.
The addition means 5 outputs an addition signal S5 obtained by adding the phase signal S4 from
the phase shift means 4 and the microphone signal S3b from the nondirectional microphone 3b
to the equalizer 6. The equalizer 6 outputs an equalizer signal S6 obtained by performing
frequency correction so that the frequency characteristic of the addition signal S5 from the
addition means 5 is substantially flat, to the terminal Tout as an output of the variable directivity
microphone device 1.
[0017]
As described above, since the variable directional microphone device 1 includes the
nondirectional microphone 3a, the nondirectional microphone 3b, the phase shift unit 4, the
adding unit 5, and the equalizer 6, the directivity of the microphone can be changed.
[0018]
FIG. 2 shows a circuit diagram of the phase shift means.
In FIG. 2, the phase shift means 4 comprises a resistor R 1, a resistor R 2, a resistor R 3, a
capacitor C 1 and an operational amplifier 10. FIG. 3 is a phase characteristic diagram of the
phase shift means. FIG. 3 shows the phase characteristic of the phase shift means 4 with the ratio
ω / ωa between the angular frequency ω and the angular frequency ωa (= 1⁄2πC1R3) with 90
° phase delay on the horizontal axis, and the phase angle φ on the vertical axis. It is
[0019]
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From FIG. 3, the phase shift means 4 shifts the phase of the microphone signal S3a from the
nondirectional microphone 3a input to the input terminal Tin in the direction of -180 ° in the
range where the angular frequency ω is greater than the angular frequency ωa, In the range
where the angular frequency ω is smaller than the angular frequency ωa, the phase is shifted in
the direction of 0 °.
[0020]
The phase shift signal S4 of the phase shift means 4 outputs a phase shift signal S4 obtained by
delaying the phase of the microphone signal S3a by 180 ° when the angular frequency ω of the
microphone signal S3a is sufficiently larger than the angular frequency ωa. When the angular
frequency ω is sufficiently smaller than the angular frequency ωa, the phase shift signal S4
which does not delay the phase of the microphone signal S3a is output.
[0021]
Assuming that resistance R1 = resistance R2 = resistance R3 in the phase shift means 4, the
phase shift means 4 outputs a phase shift signal S4 having an amplitude equal to that of the
microphone signal S3a over the phase 0 ° to 180 °.
[0022]
FIG. 4 is a frequency characteristic diagram with respect to the incoming sound angle θ of the
addition means of the variable directional microphone device according to the present invention.
FIG. 4 shows an incoming sound angle θ (0 °, 90 °, 180 °) to the nondirectional microphone
3a and the directional microphone 3b disposed on the axis 8, and an angular frequency ωa of 90
° phase delay is 340 Hz. Shows the frequency f (Hz) versus response Rp (dB) characteristics of
the addition signal S5 of the variable directional microphone device 1 when the distance D
between the nondirectional microphone 3a and the nondirectional microphone 3b is 2 cm. It is.
[0023]
FIG. 5 is a directivity pattern diagram of the variable directional microphone device according to
the present invention.
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FIG. 5 shows an omnidirectional microphone disposed on the axis 8 with the incoming voice
angle 90 ° phase delay angular frequency ωa of 340 Hz, the distance D between the
nondirectional microphone 3a and the nondirectional microphone 3b being 2 cm. The directivity
pattern of the variable directivity microphone apparatus 1 at the frequency f (= 100 Hz, 1 KHz, 5
KHz) of the incoming voice to 3a and the nondirectional microphone 3b is shown.
[0024]
As shown in FIGS. 4 and 5, the overall characteristics of the variable directional microphone
device 1 are non-directional characteristics at low frequencies and low unidirectional
characteristics at 180 ° in mid frequencies, It has bi-directional characteristics with low
response in the 90 ° and 270 ° directions at high frequencies.
[0025]
As described above, according to the directivity pattern shown in FIG. 5, the variable directional
microphone device 1 is capable of sound collection from the 180 ° direction, and the response
of the frequency (1 KHz to 3 KHz) with high aural sensitivity is lowered. Therefore, it is possible
to lower the auditory sensitivity of the incoming sound from the 180 ° direction to the incoming
sound from the 0 ° direction.
[0026]
Also, the variable directional microphone device 1 is configured by arranging the nondirectional
microphone so that the noise source with the offending frequency f (1 KHz to 3 KHz) is in the
direction of low response due to noise from inside the video integrated camera. , The influence
from the noise source can be reduced.
[0027]
Furthermore, since the variable directional microphone device 1 is configured to perform reverse
phase addition at high frequencies, the influence of vibration in the video integrated camera can
be reduced.
[0028]
Furthermore, since the variable directional microphone device 1 performs in-phase addition and
averaging of wind noise distributed in a low frequency band of 200 Hz or less where correlation
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among outputs of the nondirectional microphone is low, the influence of wind noise is reduced.
can do.
In addition, since it has a unidirectional response with a low response in the 180 ° direction, it
is possible to pick up the sound of the camera operator.
[0029]
Although the variable directional microphone device described above has described the variable
directional microphone device 1 including two nondirectional microphones, the present
invention is not limited to this, and two or more nondirectional microphones may be used. The
present invention is also applied to a variable directional microphone device that includes and
phase-shifts and adds signals from a plurality of nondirectional microphones.
[0030]
According to the present invention, the output phase from at least one nondirectional
microphone among the plurality of nondirectional microphones and the plurality of
nondirectional microphones is varied in the range of 0 ° to 180 °. The directivity of the
microphone comprising: phase means; summing means for summing the output of at least one
non-directional microphone other than the non-directional microphone whose output phase is
varied by the phase shift means and the output of the phase shift means When the variable
directional micro-pong is mounted on, for example, a video integrated camera etc., the influence
of vibration from inside the equipment and the vibration and wind due to camera shake of the
camera operator is reduced, and the camera operator's Sound collection is possible, and the
target sound can be collected at an appropriate volume.
[0031]
Brief description of the drawings
[0032]
1 is a schematic configuration diagram of a variable directional microphone device according to
the present invention
[0033]
Fig. 2 Circuit diagram of phase shift means
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[0034]
Fig. 3 Phase characteristic of phase shift means
[0035]
Fig. 4 Frequency characteristic diagram of the addition means of the variable directional
microphone device according to the present invention with respect to the angle θ
[0036]
Directivity pattern of the variable directional microphone device according to the present
invention
[0037]
Fig. 6 Schematic diagram of the variable directional microphone
[0038]
Fig. 7 Directivity pattern of variable directional microphone
[0039]
Explanation of sign
[0040]
DESCRIPTION OF SYMBOLS 1 ... Variable directivity microphone apparatus, 3a, 3b ...
Nondirectional microphone, 4 ... Phase shift means, 5 ... Addition means, 6 ... Equalizer, 10 ... Op
amp, C1 ... Capacitor, D ... Distance, f ... Frequency (Hz) , R1, R2, R3: resistance, Rp: response (dB),
Sa, Sb: incoming voice, S3a, S3b: microphone signal, S4: phase signal, S5: addition signal, S6:
equalizer signal, Tin: input terminal , Tout: output terminal, θ: angle of incoming sound wave, φ:
phase angle, ω, ωa: angular frequency.
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