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JP2002223493

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DESCRIPTION JP2002223493
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
multi-channel sound collecting device for collecting multi-channel sound at one point (one place).
[0002]
2. Description of the Related Art In television broadcasting, a 3-channel 4-channel stereo system
has been put to practical use, and in recent years, a 3--2 channel 5-channel stereo system
represented by a DVD has been commercialized.
[0003]
With the widespread use of multi-channel stereo in television broadcasting and DVD, there is a
growing demand for multi-channel stereo in cameras for home video use (hereinafter referred to
as video cameras).
[0004]
Sound creation in a broadcast program or DVD software mixes the material collected by
arranging many microphones close to each sound source or the material collected separately in
advance, and the sound field of the desired sound image localization It is based on creating.
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This is a method generally used from the 2-channel stereo age.
[0005]
On the other hand, in a video camera, it is necessary to separate and collect sound from multiple
directions with one sound collecting device attached to the video camera at the time of recording,
and to record in real time.
[0006]
As the conventional multi-channel sound collecting devices, those described in Japanese Patent
Application Laid-Open Nos. 4-137997, 5-191886, 5-191887, and 6-7368 are known. .
In any of these, a plurality of directional microphones with directional axes directed at a
predetermined angle are mounted in the same housing, and only by arranging one of the sound
collection devices in the sound field, multi-channel sound can be collected. It makes sound
possible.
[0007]
Furthermore, in addition to the above-mentioned conventional example, in order to improve the
separation sound collecting performance of the front three channels, Japanese Patent Application
Laid-Open No. 5-83784 devises the directivity of the L channel microphone and the R channel
microphone. A multi-channel sound pickup device that can be mounted on a video camera is
described.
[0008]
Furthermore, in Japanese Patent Application Laid-Open Nos. 5-64289, 5-260585 and 6-54242, a
video camera is equipped with a plurality of nondirectional microphones, and the output is signal
processed to obtain a video camera. A two-channel stereo sound pickup device is described
which obtains a stereo signal suitable for.
[0009]
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FIG. 12 shows the configuration of a conventional two-channel stereo sound pickup apparatus
described in Japanese Patent Laid-Open No. 5-260585.
FIG. 13 and FIG. 14 show the detailed configuration of each combining means in FIG.
[0010]
In FIG. 12, 51 is a first nondirectional microphone disposed at the front, 52 is a second
nondirectional microphone disposed at the rear, 53 is a third nondirectional microphone
disposed at the left, and 54 Is a fourth omnidirectional microphone disposed on the right, 55 is a
first combining means, 56 is a second combining means, 57 is a third combining means, 58 is a
fourth combining means, 59 is a control means It is.
[0011]
In the first combining means 55 of FIG. 13, 60 is a delay unit, and 61 is a subtractor.
The second combining unit 56 and the third combining unit 57 have the same configuration as
the first combining unit 55.
In FIG. 14, 62 is a first attenuator, 63 is a second attenuator, 64 is a third attenuator, 65 is a first
adder, and 66 is a second adder.
[0012]
As shown in FIG. 13, in the first combining means 55 of FIG. 12, first, the sound wave propagates
the distance from the second nondirectional microphone 52 to the first nondirectional
microphone 51 by the delay device 60. The output of the second microphone 52 is delayed by
time.
Next, the subtractor 61 subtracts the output of the delay 60 from the output of the first
nondirectional microphone 51. With the above configuration, the output of the primary sound
pressure gradient type unidirectional microphone shown by the polar pattern in FIG. 13 can be
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obtained from the first combining means 55.
[0013]
Thereafter, the same processing is performed by the second combining means 56 and the third
combining means 57 of FIG. 12, and the outputs of three directional microphones shown by
polar patterns of FIG. 15 are obtained.
[0014]
Next, these three outputs are input to the fourth combining means 58 shown in FIG.
The output of the first combining means 55 is gain adjusted by the attenuator 62, and the output
of the second combining means 56 is gain adjusted by the attenuator 63. The adder 65 adds the
two and combines the L channel output. Similarly, after the output of the third combining means
57 is gain adjusted by the attenuator 64, it is added to the output of the attenuator 62 at the
adder 66 to obtain an R channel output.
[0015]
The gain of the first attenuator 62 and the gains of the second attenuator 63 and the third
attenuator 64 are the second attenuator 63 and the third attenuation when the gain of the first
attenuator 62 is high. The video camera zoom lens is controlled by the control means 59 such
that the gain of the first attenuator 62 is low and the gains of the second attenuator 63 and the
third attenuator 64 are high when the gain of the first attenuator 62 is low. It is controlled in
conjunction with
[0016]
That is, as shown in FIG. 16, at the wide-angle end, the gain of the first attenuator 62 is set to the
lowest, and the output of the second combining means 56 is the output of the third combining
means 57 as the L channel output. Is the output of the R channel.
On the telephoto side, the gains of the second attenuator 63 and the third attenuator 64 are set
to the lowest, and the output of the first combining means 55 is the output of the L channel and
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the R channel.
[0017]
With the above configuration, a zoom microphone in which the directivity changes in conjunction
with the zoom lens can be obtained.
[0018]
Although the conventional sound pickup apparatus of FIG. 12 is a compact and low-cost
apparatus using four omnidirectional microphones, it is a sound pickup apparatus for twochannel stereo and is It did not correspond to channel stereo.
[0019]
In video cameras, there is a demand for a small-sized, low-cost, multi-channel sound pickup
device compatible with multi-channel stereo with a zoom function.
[0020]
An object of the present invention is to realize a small-sized, low-cost multi-channel sound pickup
device for multi-channel stereo that can be mounted on a video camera.
[0021]
[Means for Solving the Problems] In order to solve this problem, a multi-channel sound collecting
apparatus according to claim 1 of the present invention comprises four non-directional
microphones arranged at the front, the rear, the left and the right. The eight first to eighth
combining the outputs of eight directional microphones whose directivity is directed at eight
directions all around in the horizontal plane at every 45 ° C. from the outputs of the four
nondirectional microphones. , And a ninth combining means for combining multi-channel stereo
signals from the outputs of the eight combining means, and only four non-directional
microphones, various sound fields, various We have realized a compact, low-cost multi-channel
sound pickup device that is compatible with multi-channel stereo.
[0022]
Also, the invention according to claim 2 arranges the four nondirectional microphones in the left
front, the right front, the left back and the right back, and obtains the same function as the
invention according to the claim 1 .
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[0023]
Furthermore, the invention according to claim 3 is premised on a 3-2 method 5-channel stereo,
and a first output state in which sounds from the side and the back are positively picked up and
the emphasis on the sound spread is emphasized, and reproduction A second output state for
high fidelity reproduction of the sound field with emphasis on consistency with the speaker
direction at the time and a third output state for obtaining an effect of approaching the sound
source with emphasis on sound from the front The ninth synthesis means switches and outputs
the three output states of the above to enable flexible sound collection according to the sound
field and purpose.
[0024]
Furthermore, in the fourth aspect of the present invention, the ninth combining means is
interlocked with the zoom lens of the video camera, the first output state at the wide angle, the
second output state at the standard time, and the third output at the telephoto As in the state, by
switching the sound collection state, a zoom microphone compatible with a 3-2 method 5channel stereo system capable of realistic sound collection synchronized with an image is
realized.
[0025]
BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be
described below with reference to the drawings.
[0026]
(First Embodiment) FIG. 1 shows a configuration of a multi-channel sound collecting apparatus
according to a first embodiment of the present invention.
[0027]
In FIG. 1, with the upper side of the drawing being a front direction, 1 is a first omnidirectional
microphone disposed in the front, 2 is a second omnidirectional microphone disposed in the rear,
3 is disposed on the left Third omnidirectional microphone 4, fourth omnidirectional microphone
4 disposed on the right, 5 forward from the output of the first omnidirectional microphone 1 and
the output of the second omnidirectional microphone 2 First combining means for combining
directional microphones having directivity, 6 is a directional microphone having directivity from
the output of the first nondirectional microphone 1 and the output of the second nondirectional
microphone 2 backward And a third combining means 7 combines a directional microphone
having directivity in the left direction from the output of the third nondirectional microphone 3
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and the output of the fourth nondirectional microphone 4. Synthetic means 8 is a fourth
combining means for combining a directional microphone having directivity in the right direction
from the output of the third nondirectional microphone 3 and the output of the fourth
nondirectional microphone 4; 9 is a first non Fifth combining means for combining a directional
microphone having directivity in the left front from the output of the directional microphone 1
and the output of the fourth nondirectional microphone 4, and 10 is an output of the first
nondirectional microphone 1 Sixth combining means for combining a directional microphone
having directivity in the right front from the output of the third omnidirectional microphone 3
and 11 is an output of the second omnidirectional microphone 2 and a fourth omnidirectional
Seventh combining means for combining a directional microphone having directivity to the left
rear from the output of the directional microphone 4, 12 is an output of the second
nondirectional microphone 2 and an output of the third nondirectional microphone 3 Eighth
combining means for combining directional microphones having directivity from the rear to the
right, 13 is a ninth combining means for combining multi-channel stereo signals from the
outputs of eight first to eighth combining means 5 to 12 The means 14 is a control means for
controlling the synthesizing method of the ninth synthesizing means 13.
[0028]
In FIG. 1, L is an L channel output in the 3-2 system 5 channel stereo, R is an R channel output,
SR is an SR channel output, SL is an SL channel output, and C is a C channel output.
This signal is reproduced by the reproduction system compatible with the 3-2 method 5-channel
stereo shown in FIG.
[0029]
The operation of the multi-channel sound collecting apparatus configured as described above will
be described below.
[0030]
The directivity synthesized by the first to eighth synthesizing means 5 to 12 in FIG. 1 is shown in
FIG.
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FIG. 4 shows the directivity of FIG. 3 in a more understandable manner.
[0031]
FIG. 5 shows the principle of directional synthesis in the first to eighth synthesizing means 5 to
12. In FIG.
[0032]
First, with the first to eighth combining means 5 to 12 shown in FIG. 1 and FIG. 3, forward,
backward, leftward, rightward, left forward, right forward, left backward, right backward shown
in FIG. Synthesize eight primary sound pressure gradient directional microphones with eight
directional directivity.
In the present embodiment in which four nondirectional microphones 1 to 4 are arranged at the
vertex of a square, the output of eight directional microphones whose directivity is directed at
every 45 ° can be obtained.
The detailed configurations of the first combining means 5 and the second combining means 6
shown in FIG. 5 are equivalent to the first combining means shown in FIG. 13 of the conventional
example.
[0033]
In FIG. 5, 15 is a first delay, 16 is a first subtractor, 17 is a second delay, and 18 is a second
subtractor.
[0034]
In the first combining means 5, first, with the first delay unit 15, the second microphone 2 only
during the time when the sound wave propagates the distance from the second nondirectional
microphone 2 to the first nondirectional microphone 1. Delay the output of
Next, the first subtractor 16 subtracts the output of the first delay device 15 from the output of
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the first nondirectional microphone 1.
According to the above configuration, the output of the primary sound pressure gradient type
uni-directional microphone whose directivity is directed forward as shown by the polar pattern is
synthesized by the first synthesis means 5.
[0035]
In the second combining means 6, the output of the first microphone 1 is the same as the
propagation time of the sound wave by the second delay device 17 in the distance from the first
nondirectional microphone 1 to the second nondirectional microphone 2. To delay.
Next, the second subtractor 18 subtracts the output of the second delay 17 from the output of
the second nondirectional microphone 2.
According to the above configuration, the output of the primary sound pressure gradient type
uni-directional microphone whose directivity is directed backward as shown by the polar pattern
is synthesized by the second synthesis means 6.
Subsequently, the same processing is performed by the third to eighth combining means 7 to 12
to obtain outputs of a total of eight primary sound pressure gradient directional microphones
shown in FIGS. 3 and 4.
[0036]
Next, the ninth synthesis means 13 of FIG. 1 synthesizes signals for multi-channel stereo from
the outputs of the eight primary sound pressure gradient directional microphones.
[0037]
If it is desired to obtain a signal of the 3-2 method 5 channel stereo, it is preferable to assign the
directivity shown in FIG. 6 to each channel in consideration of the speaker arrangement of FIG. 2
and the directivity of the primary sound pressure gradient type.
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Therefore, in this embodiment, as can be understood from FIG. 3, the output of the first
combining means 5 is C-channel, the output of the fifth combining means 9 is L-channel, and the
output of the sixth combining means 10 is The ninth combining means 13 is controlled by the
control means 14 of FIG. 1 so as to output the output of the R channel seventh combining means
11 to the SL channel and the output of the eighth combining means 12 to the SR channel. .
[0038]
According to the present embodiment described above, it is possible to obtain a 5-channel signal
compatible with the 3-2 method 5-channel stereo only by arranging four nondirectional
microphones, and it is a compact and low cost multi A channel sound collecting device can be
realized.
[0039]
In particular, in consideration of mounting on a video camera, the small size is an extremely great
advantage.
In the market, the demand for smaller and lighter video cameras is extremely large.
When mounting the microphones, considering the mounting mechanism and wiring, the
mounting area per microphone is extremely large, and the utility of being able to configure eight
directional microphones with only four microphones is extremely large.
In addition, it is a great advantage that only four microphone AD converters, which are essential
elements for digital signal processing, are required.
[0040]
The allocation example of each combining means output to the 5-channel stereo signal shown in
FIG. 6 assumes a standard sound collecting purpose and sound field, and according to the
present embodiment, the position and noise of the sound source The directivity of each channel
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can be freely changed according to the condition of the sound field such as echo, and a multichannel sound collecting device can be realized which can be flexibly adapted to the purpose of
sound collection and the condition of the sound field.
As described in the prior art, it is also possible to synthesize a microphone whose directivity is
directed in the middle by weighted averaging the outputs of the two directional microphones.
[0041]
Preferably, the levels of the outputs C, L, R, SL, and SR are set to optimal level distribution
depending on the purpose of sound collection and the conditions of the sound field.
For example, when there is much ambient noise or when it is desired to obtain an effect of
approaching a sound source, it is preferable to make level distribution of (output C, output L,
output R)> (output SL, output SR).
[0042]
Second Embodiment FIGS. 7 and 8 show the configuration of a multi-channel sound pickup
apparatus according to a second embodiment of the present invention.
[0043]
In FIG. 7, with the upper side of the drawing as the front direction, 21 is the first nondirectional
microphone disposed in the front left direction and 21 is the second nondirectional microphone
disposed in the front right side. , 23 is a third omnidirectional microphone disposed at the rear
left, and 24 is a fourth omnidirectional microphone disposed at the rear right.
[0044]
In FIG. 8, 25 is a first combining means for combining a directional microphone having
directivity in front from the output of the first nondirectional microphone 21 and the output of
the third nondirectional microphone 23, and 26 is a first combining means Second synthesizing
means for synthesizing a directional microphone having directivity from the output of the two
nondirectional microphones 22 and the output of the fourth nondirectional microphone 24; 27 is
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a first nondirectional microphone 21; Third combining means for combining a directional
microphone having directivity in the left direction from the output of the second omnidirectional
microphone 22 and the output of the third omnidirectional microphone 23 and a fourth
combining means 28 Fourth combining means for combining a directional microphone having
directivity in the right direction from the output of the nondirectional microphone 24; 29 is an
output of the first nondirectional microphone 21; Fifth combining means for combining a
directional microphone having directivity in the left front from the output of the nondirectional
microphone 24, and 30 is an output of the second nondirectional microphone 22 and a third
nondirectional microphone 23 Sixth combining means for combining a directional microphone
having directivity to the right front from the output, 31 is left backward from the output of the
second nondirectional microphone 22 and the output of the third nondirectional microphone 23
Seventh combining means for combining directional microphones having directivity, 32 is
directivity having right directivity from the output of the first omnidirectional microphone 21
and the output of the fourth omnidirectional microphone 24 It is an eighth combining means for
combining microphones.
The processes of the eight combining means 25 to 32 and after are performed by the ninth
combining means 13 and the control means 14 which are the same as in the first embodiment of
FIG. 1, and the illustration and description thereof will be omitted.
[0045]
The principle of the second embodiment is the same as that of the first embodiment shown in
FIGS. 1 and 3, and the difference between the first embodiment of FIG. 3 and the present
embodiment of FIG. 8 is four. The arrangement of the nondirectional microphones is rotated by
45 °, and the nondirectional microphones serving as the inputs of the first to eighth combining
means 25 to 32 are changed based on this difference.
[0046]
The principle and performance of this embodiment are exactly the same as the invention of the
first embodiment, and when mounted on a video camera or the like, either one may be selected in
consideration of the design.
[0047]
(Embodiment 3) FIG. 9 shows directivity characteristics of the output of each channel of the
multi-channel sound collecting system in Embodiment 3 of the present invention.
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The present embodiment relates to the combining means 13 and the control means 14 of FIG. 1,
and provides an optimum sound collecting system according to the sound collecting purpose in
the 3-2 type 5-channel stereo.
Hereinafter, the present embodiment shown in FIG. 9 will be described with reference to FIG.
[0048]
In FIG. 9, in the first output state, the output of the first combining means 5 of FIG. 1 is a C
channel signal, the output of the third combining means 7 is an L channel signal, and the output
of the fourth combining means 8 is Is an R channel signal, and the output of the second
combining means 6 is an SL and SR channel signal.
[0049]
In the second output state, the output of the first combining means 5 of FIG. 1 is a C channel
signal, the output of the fifth combining means 9 is an L channel signal, and the output of the
sixth combining means 10 is an R channel signal. The output of the seventh combining means 11
is an SL channel signal, and the output of the eighth combining means 12 is an SR channel signal.
[0050]
In the third output state, the output of the first combining means 5 of FIG. 1 is a C channel signal,
the output of the fifth combining means 9 is an L channel signal, and the output of the sixth
combining means 10 is an R channel signal. The output of the third combining means 7 is an SL
channel signal, and the output of the fourth combining means 8 is an SR channel signal.
[0051]
In this embodiment, the ninth combining means 13 and the control means 14 in FIG. 1 have a
function of switching and outputting the three first to third output states.
[0052]
The first output state shown in FIG. 9 actively picks up the sound from the side and the back, and
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while there is a sound source for the purpose of sound collection in the surroundings, it enters
into the sound field and is collected. It is a sound collection method suitable for sounding.
The second output state is a sound collection method suitable for the case where the sound
source to be picked up is in the front and the sound in the rear is also collected to convey the
atmosphere of the sound field, and this collection method is the most common. Seems to be
The third output state is a sound collecting method suitable for the case where a sound source to
be picked up is ahead and a state approaching the sound source is desired.
[0053]
In addition to the above-described selection according to the purpose of collecting sound, it is
also possible to select the third output state in a sound field with a lot of noise and echo.
[0054]
As described above, according to the present embodiment, it is possible to realize a multi-channel
sound collecting device that can flexibly cope with the sound collecting method suitable for the
purpose of sound collection and the condition of the sound field.
[0055]
(Fourth Embodiment) FIG. 10 shows the configuration of a multi-channel sound collecting system
according to a fourth embodiment of the present invention, and FIG. 11 shows the directivity of
each channel output according to the present embodiment.
This embodiment is an output switching function provided to the ninth combining means 13 and
the control means 14 shown in FIG. 1 in the above-mentioned third embodiment, that is, the
multi-channel sound collecting apparatus shown in FIG. Switching of the three first to third
output states, which are the directivity of each channel output, is interlocked with zoom control
which is lens drive control such as telephoto and wide angle in a video camera.
[0056]
In FIG. 10, reference numerals 1 to 12 have the same configuration and effects as those of
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reference numerals 1 to 12 shown in FIG. 1 in the first embodiment, and 41 indicates the output
of the second to eighth combining means 6 to 12 A ninth combining means for inputting, 42 is a
zoom control means, and 43 is a lens driving mechanism.
[0057]
In the present embodiment, the zoom control means 42 of the video camera controls the lens
drive mechanism 43 and at the same time controls the ninth combining means 41, and as shown
in FIG. By switching the sound collection state continuously to the second output state, such as to
the third output state at the time of telephoto, it is possible to have a realistic sound collection
synchronized with the video. Zoom microphone can be realized.
Also, as shown in the conventional example, by taking a weighted average of two directional
microphones, it is possible to change the direction of directivity continuously between them.
[0058]
As described above, according to the invention as set forth in claim 1 of the present invention,
four nondirectional microphones disposed at the front, rear, left, right side, and the four
nondirectional microphones Eight first to eighth combining means for combining the outputs of
eight directional microphones whose directivity is directed in eight directions all around in the
horizontal plane at intervals of 45 ° C. from the output of the microphone, and the eight And a
ninth combining means for combining a multi-channel stereo signal from the output of the
combining means, so that only four non-directional microphones, various sound fields, multichannel stereos of various systems are provided. The effect of being able to realize a compact,
low-cost multi-channel sound pickup device that can cope with
[0059]
According to the second aspect of the present invention, the four nondirectional microphones are
arranged at the left front, the right front, the left back, and the right back, and the same effects as
the first aspect of the invention can be obtained. Is obtained.
[0060]
Furthermore, according to the third aspect of the present invention, the first output state in
which the sound from the side and the back is positively picked up and the emphasis on the
sound spread is emphasized, and the correspondence between the speaker direction at the time
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of reproduction and Three output states, the second output state for high fidelity reproduction of
the sound field, and the third output state for obtaining an effect of approaching the sound
source with emphasis on the sound from the front, By switching and outputting the synthesizing
means of (1), it is possible to obtain an effect that sound collection for the 3-2 system 5 channel
stereo which is optimum according to the sound field and the purpose becomes possible.
[0061]
Further, according to the fourth aspect of the present invention, the ninth combining means is
interlocked with the zoom lens of the video camera, the first output state at the wide angle, the
second output state at the standard time, the third output state. By switching the sound collection
state continuously, it is possible to realize a zoom microphone compatible with the 3-2 method 5channel stereo, capable of realistic sound collection synchronized with the image. Be
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