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JP2006303839

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DESCRIPTION JP2006303839
PROBLEM TO BE SOLVED: To provide a microphone capable of obtaining a sense of wideness
and presence even when a four-channel microphone is connected to a two-channel audio device.
SOLUTION: Audio signals FL1, FR1, and RL1 recorded by a four-channel microphone unit , RR1
from the input terminals 21-24. When a 4-channel audio device is connected, the changeover
switch 15 is opened and the input signal is output as 4-channel sound signals FL, FR, RL and RR.
When 2-channel audio equipment is connected, switch 15 is closed to set the front left audio
signal FL1 to the reverse phase signal (FR2) of the front right audio signal and the in-phase
signal (RL1) of the rear left audio signal. The mixed left channel sound signal L is output to the
output terminal 21, and the front right audio signal FR1 is the reverse phase signal (FL2) of the
front left audio signal and the in-phase signal (RR1) of the rear right audio signal. The mixed
right channel sound signal R is output to the output terminal 22. [Selected figure] Figure 3
マイクロホン
[0001]
The present invention relates to a microphone having a function capable of adapting a fourchannel microphone to a two-channel audio device.
[0002]
Conventionally, in a four-channel microphone that records sound signals corresponding to four
channels of front left channel, front right channel, rear left channel, and rear right channel, for
example, as described in Patent Document 1 below, four channels are used. It has been proposed
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to obtain surround audio signals.
Further, as described in Japanese Patent Application Laid-Open No. 5-191887, four channels of
audio signals are obtained using two unidirectional microphone units and one bidirectional
microphone unit. So-called MS microphones have been proposed. JP-A-57-42296
[0003]
The four-channel microphone was the only functional category to be compatible with fourchannel audio equipment. Therefore, when a four-channel microphone is connected to a twochannel audio device, only two of the four channels can be effectively used, and the function as a
four-channel microphone can not be fully utilized.
[0004]
That is, when performing 2-channel reproduction using a 4-channel microphone, it was not
possible to obtain a sense of spread or a sense of realism.
[0005]
Therefore, for example, the sound signal of the front right channel of the four-channel
microphone is mixed with the normal phase signal of the rear right channel, and the reverse
phase signal of the rear left channel is mixed, and the sound signal of the front left channel is
mixed with the rear left channel. By mixing the normal phase signals of the rear right channel
and the reverse phase signal of the rear right channel, it is possible to effectively use the four
channel sound source even in normal two-channel reproduction to obtain a sense of spread and
presence Conceivable.
[0006]
However, when configured in this manner, there is the following contradictory phenomenon in
the direction reproducibility.
That is, for example, when the sound of the right-hand rear right phase component is small
among the components of the synthesized right signal, the right-hand rear opposite phase
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component of the synthesized left signal is localized in the sound field, and it is in the rear right A
phenomenon occurs in which the sound that should be heard is from the front left, and the sound
that should be on the back left is also heard from the front right.
This is because the positive phase output component of the antiphase sound source is small.
[0007]
Therefore, the synthesis amount of the reverse phase component can not be increased. In
addition, if the reverse phase component is small, the effects of spreading and presence will be
reduced.
[0008]
The present invention has been made in view of the above points, and its object is to use a 4channel sound source even when a 4-channel microphone is connected to a 2-channel audio
device, and to use a 4-channel sound source even in normal 2-channel reproduction. It is an
object of the present invention to provide a microphone which can obtain a sense of wideness
and presence, and which is excellent in direction reproducibility, by effectively using.
[0009]
In 2-channel reproduction of 2-channel audio equipment, in order to obtain a sense of breadth
and presence, it is generally realized by processing a 2-channel sound source.
As this processing process, the phase of the sound source of 2 channels L and R is inverted, and
the method of adding the voice which adjusted the level to the original L and R in reverse, the
sound source of 2 channels L and R differential amplifier In addition to the above, the level of its
output is adjusted, and it is added to the original L and R so as to be in opposite phase, and the
sound source of 2 channels L and R is added to the differential amplifier, and the level of its
output is adjusted , Phase delay, and adding to original L and R.
[0010]
On the other hand, according to the present invention, of the four channel (front left, right, rear
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left and right) sound sources, the above two processings are applied to the front left and right
two sound sources. By adding the rear right channel to the right channel, the four channel sound
source is effectively used, and it is configured to be able to effectively express both a sense of
expansion and a sense of presence compared to a method using two channels as a sound source.
[0011]
Furthermore, a sound that should be on the rear left can be heard from the front right, and
similarly, a sound that should be on the rear right can not be heard from the front left, and good
direction reproducibility can be obtained.
[0012]
That is, according to the present invention, a four-channel sound signal introducing means for
inputting sound signals corresponding to four channels of a front left channel, a front right
channel, a rear left channel, and a rear right channel, having a plurality of microphone units A
four-channel signal circuit that outputs a four-channel sound signal corresponding to four
channels input by the sound signal introduction unit, and a two-channel sound signal from the
four-channel sound signal input by the four-channel sound signal introduction unit There is a
circuit for creating and outputting a circuit that mixes the sound signal of the front right channel
with the antiphase signal of the front left channel and mixes the sound signal of the front left
channel with the antiphase signal of the front right channel. Output of the 2-channel signal
circuit and the 4-channel sound signal and It is characterized in that a changing switch means.
[0013]
The two-channel signal circuit further includes a circuit that mixes the in-phase signal of the rear
left channel with the sound signal of the front left channel and mixes the in-phase signal of the
rear right channel with the sound signal of the front right channel. It is characterized by
[0014]
In addition, the negative phase signal level of each channel to be mixed is set to a level not
exceeding the level of the in-phase signal of each mixed channel within the range of the main
directivity angles of the plurality of microphone units. It is characterized.
[0015]
Further, the four-channel sound signal introducing means is characterized in that it has
directivity and includes first to fourth microphone units disposed with their central axes shifted
by 90 ° from each other.
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[0016]
Further, the four-channel sound signal introducing means is deviated by 90 ° with respect to
the directions of the first and second microphone units of unidirectionality and the first and
second microphone units directed in opposite directions to each other. And adding the outputs of
the first and third microphone units to obtain a sound signal of the front left channel, and adding
the outputs of the first and third microphone units to the first and third microphone units. The
outputs are subtracted to obtain the sound signal of the front right channel, the outputs of the
second and third microphone units are added to obtain the sound signal of the rear left channel,
and the outputs of the second and third microphone units are And an operation unit for
obtaining a sound signal of the rear right channel by subtraction.
[0017]
In the above configuration, when the microphone of the present invention is connected to a fourchannel audio device, the switching means is switched to the four-channel sound signal output
side.
Then, the four-channel sound signal of the front left channel, front right channel, rear left
channel and rear right channel introduced from the plurality of microphone units is output as it
is via the four channel signal circuit, and four channel reproduction is performed. .
[0018]
When the microphone of the present invention is connected to a two-channel sound device, the
switching means is switched to the two-channel sound signal output side.
Then, the two-channel signal circuit mixes, for example, the negative phase signal of the front left
channel introduced from the plurality of microphone units into the sound signal of the front right
channel, and the negative phase signal of the front right channel is The sound signal is mixed, the
signal of the rear right channel is mixed with the sound signal of the front right channel, and the
signal of the rear left channel is mixed with the sound signal of the front left channel to create
and output a 2-channel sound signal.
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Two channel reproduction is performed by this.
[0019]
At this time, the sound is not localized at the center of the left and right speakers, since the sound
of the opposite phase of the front left channel is mixed in the front right channel and the sound
of the opposite phase in the front right channel is mixed in the front left channel. The sense of
localization of the sound is blurred, and the left and right speakers are broadened.
In addition, the sounds recorded from the rear of the mix will be more realistic.
[0020]
(1) According to the present invention, it is possible to obtain a two-channel sound signal that
effectively utilizes all the four channel sound sources.
For this reason, when a 2-channel audio device is connected and played back, a sense of spread
and presence are effectively expressed.
[0021]
In particular, compared to the conventional method of processing a two-channel sound source, a
sense of spread and reality can be obtained, and good direction reproducibility can be obtained.
Moreover, the effect is further enhanced by combining with the image.
[0022]
Furthermore, the microphone of the present invention provides added value that can be used not
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only for four-channel audio devices but also for two-channel audio devices.
(2) According to the invention described in claim 4, in the microphones including the first to
fourth microphone units which have directivity and are disposed with the central axes shifted by
90.degree. The same effect as the above can be obtained. (3) According to the invention
described in claim 5, the unidirectional first and second microphone units directed in opposite
directions to each other and the directions of the first and second microphone units are
described. So-called MS (Mid-) having a bidirectional third microphone unit oriented at a
90.degree. Direction and obtaining four channels of sound signals from the outputs of these
three microphone units. In the Side) microphone, the same effect as the above (1) can be
obtained.
[0023]
Hereinafter, embodiments of the present invention will be described with reference to the
drawings. FIG. 1 shows the appearance of an embodiment in which the present invention is
applied to a video camcorder capable of recording video and audio. In FIG. 1, a four-channel
microphone 20 having four directional microphone units 11 to 14 and a changeover switch 15 is
attached to a main body 10 of the video camcorder.
[0024]
The directional microphone unit 11 is disposed toward the front left side of the camera and
records a sound source (FL) of the front left channel.
[0025]
The directional microphone unit 12 is disposed toward the front right side of the camera and
records a sound source (FR) of the front right channel.
[0026]
The directional microphone unit 13 is disposed toward the rear left of the camera and records a
sound source (RL) of the rear left channel.
[0027]
The directional microphone unit 14 is disposed toward the rear right of the camera and records a
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sound source (RR) of the rear right channel.
[0028]
The changeover switch 15 is a changeover switch for switching between a 4-channel audio
device use mode and a 2-channel audio device use mode. For example, when the open mode 4
channel audio device use mode is selected, the directional microphone units 11 to 14 are used.
When the 4-channel sound signal recorded in is output as it is and closed and the 2-channel
sound equipment usage mode is selected, the 4-channel sound signal recorded in the directional
microphone units 11 to 14 is effectively used to create The two-channel sound signal is output.
[0029]
FIG. 2 shows the electrical configuration of the four-channel microphone 20 and the planar
arrangement of the directional microphone units 11-14.
In FIG. 2, the encoder 1 does not operate when the changeover switch 15 is opened (when the 4channel audio device use mode is selected), and the 4-channel sound source recorded by the
directional microphone units 11 to 14 is 4-channel sound as it is It is output as the signals FL,
FR, RL, RR.
[0030]
Also, the encoder 1 operates when the changeover switch 15 (FIG. 3) is closed (when the 2channel audio device use mode is selected), and the 2-channel sound from the 4-channel sound
source recorded by the directional microphone units 11 to 14 The signals L and R are created
and output.
At this time, the sound signals RL and RR of the rear left channel and the rear right channel are
not used.
[0031]
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Next, the detailed circuit of the encoder 1 will be described with reference to FIG.
In FIG. 3, the front left audio signal FL1 recorded by the directional microphone unit 11 is input
to the input terminal 21I, and the front right audio signal FR1 recorded by the directional
microphone unit 12 is input to the input terminal 22I. The rear left audio signal RL1 recorded by
the directional microphone unit 13 is input to the input terminal 23I, and the rear right audio
signal RR1 recorded by the directional microphone unit 14 is input to the input terminal 24I. .
[0032]
The input terminal 21I is connected to the input terminal of the inverting amplifier 27FL which
inverts the phase, and is connected to one input terminal of the adder 25L, and the output
terminal of the adder 25L is connected to the output terminal 21O.
[0033]
The input terminal 22I is connected to the input terminal of the inverting amplifier 27FR that
inverts the phase, and is connected to one input terminal of the adder 25R, and the output
terminal of the adder 25R is connected to the output terminal 22O.
[0034]
The input terminal 23I is connected to the output terminal 23O and also connected to one end of
the level adjustment resistor 26RL1.
[0035]
The input terminal 24I is connected to the output terminal 24O and also connected to one end of
a level adjusting resistor 26RR1.
[0036]
The output end of the inverting amplifier 27FL is connected to one end of a level adjusting
resistor 26FL2, and the output end of the inverting amplifier 27FR is connected to one end of a
level adjusting resistor 26FR2.
[0037]
The common connection point between the other ends of the resistor 26RL1 and the resistor
26FR2 is connected to the other input end of the adder 25L via the contact 15L of the
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changeover switch 15.
[0038]
A common connection point between the other ends of the resistor 26RR1 and the resistor
26FL2 is connected to the other input end of the adder 25R via the contact 15R of the
changeover switch 15.
[0039]
The contacts 15L and 15R of the changeover switch 15 are interlocked.
[0040]
In the circuit configured as described above, when connecting to a 4-channel audio device, the
changeover switch 15 is opened.
In this case, the four-channel voices input from the input terminals 21I to 24I are output as they
are from the output terminals 21O to 24O as four channel sound signals FL, FR, RL, and RR.
[0041]
When connecting to a two-channel audio device, the changeover switch 15 is closed.
In this case, the phase difference signal FR2 is obtained by inverting the phase of the front right
audio signal FR1 input from the input terminal 22I by the inverting amplifier 27FR and adjusting
the level by the resistor 26FR2, and the rear left audio signal RL1 input from the input terminal
23I. The in-phase signal whose level is adjusted by 26RL1 is applied to the adder 25L via the
contact 15L.
[0042]
Therefore, a left channel sound signal L obtained by mixing the front left audio signal FL1 with
the negative phase signal of the front right audio signal (FR2) and the in-phase signal of the rear
left audio signal (RL1) to the front left audio signal FL1. Is output.
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[0043]
Further, the phase difference of the front left audio signal FL1 input from the input terminal 21I
is inverted by the inverting amplifier 27FL and the level is adjusted by the resistor 26FL2, and
the backward right audio signal RR1 input from the input terminal 24I is leveled by the resistor
26RR1 The adjusted in-phase signal is applied to the adder 25R via the contact 15R.
[0044]
Therefore, a right channel sound signal R obtained by mixing the front right audio signal FR1
with the negative phase signal (FL2 minutes) of the front left audio signal and the in-phase signal
(RR1 minute) of the rear right audio signal at the output terminal 22O. Is output.
[0045]
For this reason, the reproduction sound by the two-channel audio equipment connected to the
output terminals 21O and 22O from which the two-channel sound signals L and R are derived is
not localized at the center of the left and right speakers, and the sense of localization of the
sound is blurred. It seems like the stereo speakers spread out.
Further, since the signals RL1 and RR1 to be mixed are collected from the rear, they become
more realistic.
[0046]
The level of the negative phase signal FL2, FR2 of each channel mixed in each of the adders 25L,
25R in FIG. 3 is within the range of the main directivity angles of the microphone units 11 to 14,
that is, an angle of 90.degree. Inside, it is adjusted by the resistors 26RL1 and 26RR1 so as not to
exceed the level of the in-phase signal of each mixed channel.
[0047]
Next, the balance between the negative-phase signal and the in-phase signal of the two-channel
sound signal L, R (pseudo 4-channel stereo) of the present invention created by mixing the
negative-phase signals FL2 and FR2 as described above, in all directions. It verifies with FIGS. 4-6
which show the polar pattern which represented the signal level.
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[0048]
FIG. 4 shows the polar pattern of the stereo microphone when the negative phase signal is well
adjusted.
In this case, it can be seen that the level of the reverse phase signal does not exceed the level of
the in-phase signal up to the left and right 120 °.
[0049]
That is, in the R channel, the 115 ° in-phase signal level is 1.75> 245 °, the out-of-phase signal
level is 1.6, and the 120 ° in-phase signal level is 1.6 = 240 °. Is 1.6, and the 125 ° in-phase
signal level is 1.4 <235 °, and the anti-phase signal level is 1.5.
[0050]
In the L channel, the in-phase signal level of 245 ° is 1.75> 115 °, the reverse-phase signal
level is 1.6, and the 240 ° in-phase signal level is 1.6 = 120 °. Is 1.6, and the in-phase signal
level of 235 ° is 1.4 <125 °, and the opposite-phase signal level is 1.5.
[0051]
FIG. 5 shows a polar pattern when the level of the negative phase signal is too small.
In this case, although the level of the negative phase signal does not exceed the level of the inphase signal, the sense of presence created by the negative phase signal is lost.
[0052]
That is, in the R channel, the 120 ° in-phase signal level is 1.6> 240 °, the reverse-phase signal
level is 1.1, and the 160 ° in-phase signal level is 0.7> 200 ° Is 0.6.
[0053]
In the L channel, the 240 ° in-phase signal level is 1.6> 120 °, the anti-phase signal level is 1.1,
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and the 200 ° in-phase signal level is 0.7> 160 ° Is 0.6.
[0054]
FIG. 6 shows, contrary to FIG. 5, a polar pattern when the level of the negative phase signal is too
large.
In this case, since the opposite phase has exceeded the level of the in-phase signal within 90 °
to the left and right, the sound on the rear left is localized to the front right, and the sound on the
rear right is localized to the front left. It will be lost.
[0055]
That is, in the R channel, the 90 ° in-phase signal level is 2.55 <270 °, the anti-phase signal
level is 2.7, and the 100 ° in-phase signal level is 2.3 <260 °. Is 2.85.
[0056]
In the L channel, the 270 ° in-phase signal level is 2.55 <90 °, the anti-phase signal level is 2.7,
and the 260 ° in-phase signal level is 2.3 <100 °. Is 2.85.
[0057]
Therefore, as a preferred embodiment of the present invention, the balance of the anti-phase
signal and the in-phase signal of the 2-channel sound signals L and R (pseudo 4-channel stereo)
has a polar pattern as shown in FIG. The respective constants of the microphone units 11 to 14,
the inverting amplifiers 27FL and 27FR in FIG. 3, and the resistors 26FL2, 26FR2, 26RL1 and
26RR1 are adjusted in advance.
[0058]
Next, the present invention is directed to the first and second microphone units which are
directed in opposite directions to each other, and to the direction 90 degrees away from the
orientation of the first and second microphone units. An embodiment applied to a MS (Mid-Side)
microphone provided with the bi-directional third microphone unit will be described with
reference to FIG.
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[0059]
In FIG. 7, the microphones 30 of the present embodiment example are unidirectional directivity
first and second microphone units 31 and 32 (M1 and M2) disposed in opposite directions
(front-rear direction), And a bi-directional third microphone unit 33 (S1) oriented in a direction
shifted by 90 ° with respect to the directions of the microphone units 31 and 32.
[0060]
The encoder 2 adds / subtracts the outputs of the three microphone units 31 to 33 to obtain four
channels of audio signals of front left (FL), front right (FR), rear left (RL), and rear right (RR).
That is, as disclosed in, for example, Patent Document 2, the encoder 2 adds the outputs of the
first and third microphone units 31 and 33 to obtain a front left audio signal, and the first and
third microphone units 31 , And 33 to obtain the front right audio signal, and the outputs of the
second and third microphone units 32, 33 are added to obtain the rear left audio signal, and the
second and third microphone units 32, 33 are obtained. To obtain the rear right audio signal.
[0061]
Each output signal of the encoder 2 is introduced to the encoder 1 configured as in FIG.
Also in the microphone 30 of FIG. 7, the same changeover switch 15 is provided (not shown).
[0062]
In the microphone 30 configured in this way, when connecting to a 4-channel audio device, the
changeover switch 15 is opened.
In this case, the encoder 1 does not operate, and the four channel sound signals obtained by the
calculation of the encoder 2 are recorded as the four channel sound signals FL, FR, RL, RR as they
are recorded by the three microphone units 31 to 33. It is output.
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[0063]
When connecting to a two-channel audio device, the changeover switch 15 is closed.
In this case, the encoder 1 operates, and 2-channel sound signals L and R are created and output
from the 4-channel audio signals calculated by the encoder 2 in the same manner as the
operation described in FIG.
At this time, the sound signals RL and RR of the rear left channel and the rear right channel are
not used.
[0064]
The two-channel signal circuit for producing and outputting a two-channel sound signal from the
four-channel sound signal according to the present invention is not limited to the use of the
inverting amplifiers 27FL and 27FR and the resistors 26FL2 and 26FR2, but the front left and
right audio signals FL1 , FR1 may be added to the differential amplifier, the level of the output
may be adjusted, and the front left and right audio signals FL1, FR1 may be added so as to be in
opposite phase to each other.
[0065]
FIG. 1 is a perspective view of an example embodiment of the present invention applied to a
video camcorder.
FIG. 1 is a configuration diagram of a four-channel microphone 20 according to an embodiment
of the present invention.
1 is a circuit diagram showing an example of an embodiment of the main part of the present
invention.
The characteristic view which shows the polar pattern of L channel and R channel in case the
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balance of a reverse phase signal is good in embodiment of this invention.
The characteristic view which shows the polar pattern of L channel and R channel in case the
reverse phase signal is too weak in the embodiment of this invention.
The characteristic view which shows the polar pattern of L channel and R channel in the case of
excess antiphase signal in embodiment of this invention.
The block diagram of the microphone 30 of the other embodiment of this invention.
Explanation of sign
[0066]
1, 2 ... encoder, 10 ... main body of video camcorder, 11-14 ... directional microphone unit, 15 ...
changeover switch, 20 ... 4 channel microphone, 21I-24I ... input terminal, 21O-24O ... output
terminal, 25L, 25R ... Adder, 26RL1, 26RR1, 26FL2, 26FR2 ... Resistor, 27FL, 27FR ... Inverting
amplifier, 30 ... Microphone, 31 ... Unidirectional first microphone unit, 32 ... Unidirectional
second microphone unit , 33 ... Bidirectional third microphone unit.
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