JPH04128494

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DESCRIPTION JPH04128494
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
stereo microphone which senses the direction of sound by outputting an output with a difference
in strength from left and right channels based on the difference between the left and right
positions of a sound source. BACKGROUND OF THE INVENTION 1. Field of the Invention The
present invention relates to a stereo microphone which senses the direction of sound by
outputting an output with a difference in strength from left and right channels based on the
difference between the left and right positions of a sound source.
[0002]
2. Description of the Related Art In a conventional stereo microphone, as shown schematically in
FIG. 5, two uni-directional microphones 1, 2 having the same performance are arranged side by
side. 2. Description of the Related Art In a conventional stereo microphone, as shown
schematically in FIG. 5, two uni-directional microphones 1, 2 having the same performance are
arranged side by side.
[0003]
The direction of the maximum sensitivity of each uni-directional microphone is inclined forward
by an opening angle θs with respect to the base line g connecting both microphones, and it
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becomes difficult for the left microphone 1 to feel the sound coming from the right, The
directivity is adjusted to separate the left and right sounds so that the microphone 2 of the above
becomes hard to feel the sound from the left side, and a good stereo feeling is to be obtained. The
direction of the maximum sensitivity of each uni-directional microphone is inclined forward by
an opening angle θs with respect to the base line g connecting both microphones, and it
becomes difficult for the left microphone 1 to feel the sound coming from the right, The
directivity is adjusted to separate the left and right sounds so that the microphone 2 of the
speaker 2 hardly feels the sound coming from the left side, and a good stereo feeling is to be
obtained.
[0004]
Since the unidirectional microphones used for stereo microphones in this way must be open to
the atmosphere from the back or the side due to their structure, the structure of the place where
they are incorporated into the audio equipment The restrictions above are large, and it is
inevitable that the casing incorporating this will also become large. Since the unidirectional
microphones used for stereo microphones in this way must be open to the atmosphere from the
back or the side due to their structure, the structure of the place where they are incorporated
into the audio equipment The restrictions above are large, and it is inevitable that the casing
incorporating this will also become large.
[0005]
Also, the inventor of the present invention previously devised a microphone (described in
Japanese Utility Model Laid-Open Publication No. 64-52393) which acts as a single
unidirectional microphone using two nondirectional microphones. . Also, the inventor of the
present invention previously devised a microphone (described in Japanese Utility Model LaidOpen Publication No. 64-52393) which acts as a single unidirectional microphone using two
nondirectional microphones. .
[0006]
The omnidirectional microphone is advantageous in miniaturizing the electric apparatus because
the space or space when incorporating it into the acoustic apparatus is small because it is not
necessary to open the back or side of the body to the atmosphere. An omnidirectional
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microphone is advantageous for miniaturizing an electrical device because there is no need to
open the back or side of the body to the atmosphere and there are few space restrictions when
incorporated into an acoustic device, and mechanical It is also less likely to generate noise due to
vibration or wind.
[0007]
In this prior art unidirectional microphone, as schematically shown in FIG. 6, two equal
performance non-directional microphones 3 and 4 are arranged at intervals, and one
microphone, for example, the left microphone, is arranged. The difference (e3-e4) between the
output e3 of 3 and the output e4 obtained by electrically delaying the output of the other (right)
microphone 4 through the delay circuit 5 is taken out and the two microphones 3 and 4 are
configured This is the output E of a unidirectional microphone. In this prior art unidirectional
microphone, as schematically shown in FIG. 6, two equal performance non-directional
microphones 3 and 4 are arranged at intervals, and one microphone, for example, the left
microphone, is arranged. The difference (e3-e4) between the output e3 of 3 and the output e4
obtained by electrically delaying the output of the other (right) microphone 4 through the delay
circuit 5 is taken out and the two microphones 3 and 4 are configured This is the output E of a
unidirectional microphone.
[0008]
The directional characteristic diagram of this output E is, for example, as shown in FIG. 7, and the
output E changes with the change of the angle θ made by the sound wave with respect to the
base line g. It becomes minimum when θ = 180 °. The directional characteristic diagram of this
output E is, for example, as shown in FIG. 7, and the output E changes with the change of the
angle θ made by the sound wave with respect to the base line g. It becomes minimum when θ =
180 °.
[0009]
The angle .theta.0 (.theta.0 = 0.degree. In FIG. 7) at which the sensitivity of this nondirectional
microphone is maximum can be changed by adjusting the delay circuit 5. FIG. The angle θ 0 (θ
0 = 180 ° in FIG. 7) at which the sensitivity of this nondirectional microphone is minimum can
be changed by adjusting the delay circuit 5.
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[0010]
[0010] As described above, the conventional stereo microphones use the unidirectional
microphones which require the back side or the side to be open to the atmosphere, so that they
can be attached to the electric equipment. Because of the limitations, the present invention seeks
to obtain stereo microphones without such limitations. [0010] As described above, the
conventional stereo microphones use the unidirectional microphones which require the back side
or the side to be open to the atmosphere, so that they can be attached to the electric equipment.
The present invention is intended to obtain a stereo microphone free from such restrictions and
noises, because the restriction is bothersome to vibration noise and wind scraping noise.
[0011]
SUMMARY OF THE INVENTION The present invention has developed a configuration for
obtaining a unidirectional microphone using the two omnidirectional microphones of the prior
invention, as shown in FIG. A delay circuit is connected to the directional microphone, and the
difference between the output of the left nondirectional microphone 3 and the output passing
through the delay circuit 6 of the right nondirectional microphone 4 is the output of the left
channel, and the right nondirectional The difference between the output of the sex microphone 4
and the output through the delay circuit 5 of the left nondirectional microphone 3 constitutes a
stereo microphone as the output of the right channel. SUMMARY OF THE INVENTION The
present invention has developed a configuration for obtaining a unidirectional microphone using
the two omnidirectional microphones of the prior invention, as shown in FIG. A delay circuit is
connected to the directional microphone, and the difference between the output of the left
nondirectional microphone 3 and the output passing through the delay circuit 6 of the right
nondirectional microphone 4 is the output of the left channel, and the right nondirectional The
difference between the output of the sex microphone 4 and the output through the delay circuit
5 of the left nondirectional microphone 3 constitutes a stereo microphone as the output of the
right channel.
[0012]
[Operation] The difference between the output e3 of the left nondirectional microphone 3 and
the output e4 passed through the delay circuit 6 of the right nondirectional microphone 4 is
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output from the terminal 11 of the left channel through the equalizer 9. Also, according to the
prior art, from this terminal 11, an output having directional characteristics as shown in FIG. 7 is
obtained. Since this direction characteristic can change the angle θ0 of maximum sensitivity
(θ0 = 0 ° in FIG. 7) by adjusting the delay circuit 5, this angle θ0 is different from the base line
g as shown in FIG. Make it come backwards. [Operation] The difference between the output e3 of
the left nondirectional microphone 3 and the output e4 passed through the delay circuit 6 of the
right nondirectional microphone 4 is output from the terminal 11 of the left channel through the
equalizer 9. Also, according to the prior art, from this terminal 11, an output having directional
characteristics as shown in FIG. 7 is obtained. This directional characteristic can change the angle
θ0 of the minimum sensitivity (θ0 = 180 ° in FIG. 7) by adjusting the delay circuit 6.
Therefore, with this adjustment, the angle θ0 with respect to the base line g as shown in FIG. To
come forward.
[0013]
A portion in front of the base line g of the directional characteristic diagram of the left
unidirectional microphone constructed as described above is drawn as a solid portion 13 in FIG.
This shows the sensitivity of the microphone 3 to the angle θ of the sound wave entering the left
microphone 3. A portion in front of the base line g of the directional characteristic diagram of the
left unidirectional microphone constructed as described above is drawn as a solid portion 13 in
FIG.
[0014]
Similarly, the difference between the output of the right nondirectional microphone 4 and the
output passing through the delay circuit 5 of the left nondirectional microphone 3 is output to
the terminal 12 of the right channel, and its directional characteristic is The portion in front of
the baseline g of the diagram is the dashed line portion 14 of FIG. Similarly, the difference
between the output of the right nondirectional microphone 4 and the output passing through the
delay circuit 5 of the left nondirectional microphone 3 is output to the terminal 12 of the right
channel, and its directional characteristic is The portion in front of the baseline g in the figure is
the dashed line portion 14 of FIG.
[0015]
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In this case, the output of the left channel is a for the sound waves coming from the A direction
in FIG. 3 and the output of the right channel is almost 0 for the sound waves coming from the B
direction. The outputs of b and the right channel are b ', and the outputs of the left and right
channels are both c for sound waves from the front C direction, and only the output d of the right
channel is output for sound waves from the D direction, This makes it possible to sense the
direction of the sound source. In this case, the output of the left channel is a for the sound waves
coming from the A direction in FIG. 3 and the output of the right channel is almost 0 for the
sound waves coming from the B direction. The outputs of b and the right channel are b ', and the
outputs of the left and right channels are both c for sound waves from the front C direction, and
only the output d of the right channel is output for sound waves from the D direction, This makes
it possible to sense the direction of the sound source.
[0016]
In this case, the opening angle .theta.s of the stereo microphones of the two microphones 3 and 4
is the angle between the directions A and D and the base line g. In this case, the opening angle
.theta.s of the stereo microphones of the two microphones 3 and 4 is the angle between the
directions A and D and the base line g.
[0017]
EXAMPLE FIG. 4 shows the frequency characteristics of the left channel output of a stereo
microphone constituted of two nondirectional microphones as described above. A solid line A is a
diagram when a sound wave comes from the direction A in FIG. 3, a broken line B is a diagram
when a sound wave comes from the front, and a line D when a sound wave comes from the D
direction. EXAMPLE FIG. 4 shows the frequency characteristics of the left channel output of a
stereo microphone constituted of two nondirectional microphones as described above. A solid
line A is a diagram when a sound wave comes from the direction A in FIG. 3, a broken line C is a
diagram when a sound wave comes from the front (the direction C in FIG. 3), and D is a diagram
when a sound wave comes from the direction D in FIG.
[0018]
In this example, the distance between the nondirectional microphones 3 and 4 is 16 mm, the
delay time of the delay circuits 5 and 6 is 40 μsec, and the opening angle θs is 30 °. In this
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example, the distance between the nondirectional microphones 3 and 4 is 16 mm, the delay time
of the delay circuits 5 and 6 is 40 μsec, and the opening angle θs is 30 °.
[0019]
[Advantage of the Invention] (1) Since a stereo microphone is configured using two
nondirectional microphones of the same performance without the need to open the back or side
to the atmosphere, the conventional unidirectionality This stereo microphone holon can be
embedded and used in any part of the device without being restricted in mounting as in the case
of using a microphone. [Advantage of the Invention] (1) Since a stereo microphone is configured
using two nondirectional microphones of the same performance without the need to open the
back or side to the atmosphere, the conventional unidirectionality This stereo microphone holon
can be embedded and used in any part of the device without being restricted in mounting as in
the case of using a microphone.
[0020]
(2) Since the two omnidirectional microphones can be mounted in line, it is not necessary to
increase the depth of the mounting portion, and the mounting volume can be reduced. (2) Since
the two omnidirectional microphones can be mounted in line, it is not necessary to increase the
depth of the mounting portion, and the mounting volume can be reduced.
[0021]
(3) Since a nondirectional microphone which is less affected by mechanical vibration and wind
noise is used, a stereo microphone less affected by these noises can be obtained. [Submission
date] June 19th, 1991 [Procedure Amendment 1] [Document Name to be Amended] Description
[Item Name for Amendment] Full Text [Improvement Method] Change [Contents of Amendment]
[Detailed Description of the Invention] (3) Using a nondirectional microphone that is less
susceptible to mechanical vibration and wind noise, a stereo microphone less susceptible to such
disturbances can be obtained.
[0022]
Brief description of the drawings
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[0023]
1 is a schematic diagram showing the configuration of the stereo microphone of the present
invention.
[0024]
2 is a diagram showing the directional characteristics of a unidirectional microphone consisting
of two omnidirectional microphones used in the present invention.
[0025]
3 is a diagram showing a portion in front of the baseline of the directional characteristics of the
output of the left and right channels.
[0026]
4 is a diagram showing the frequency characteristics of the output of the left channel when the
sound wave comes from the A, B, C direction.
[0027]
5 is a schematic diagram showing the configuration of a stereo microphone using two
conventional unidirectional microphones.
[0028]
6 is a schematic diagram showing the configuration of obtaining a unidirectional microphone
using two omnidirectional microphones of the prior invention.
[0029]
7 is a directional characteristic diagram of this.
[0030]
Explanation of sign
[0031]
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1 Unidirectional Microphone 2 Unidirectional Microphone 3 Nondirectional Microphone 4
Nondirectional Microphone 5 Delay Circuit 6 Delay Circuit 9 Equalizer 10 Equalizer 11 Terminal
12 Terminal 13 Solid Line Part 14 Dotted Line Part g Baseline
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