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JP2000197178

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This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
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DESCRIPTION JP2000197178
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
microphone directivity control apparatus and the like for controlling the direction of a directional
microphone in an arbitrary direction by electrical processing when collecting sound at the time
of imaging with a video camera or the like.
[0002]
2. Description of the Related Art As a device for controlling the directivity of microphones, a
plurality of nondirectional microphones are arranged on a plane to obtain first-to-high-order bidirectionality and their synthesized directional characteristics, and these are obtained. There has
been proposed a microphone device in which characteristics with narrow directivity are obtained
by multiplying the characteristics by a constant corresponding to the target angular direction
(see, for example, Japanese Patent Application Laid-Open No. 6-269082).
[0003]
However, in order to realize the above-mentioned apparatus, at least six nondirectional
microphones must be disposed on a plane, and in synthesizing their directivity. There is also a
problem that it is necessary to do quite complicated processing.
In addition, there is also a problem that it is difficult to obtain the same combined directivity over
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360 degrees in the horizontal direction because the centers of the combined directional
characteristics of the microphones differ depending on the physical distance between the
microphones.
[0004]
Therefore, the present invention provides a directivity control device that can obtain uniform
single narrow directivity characteristics over 360 degrees in the horizontal direction by using a
microphone device with a more simplified configuration and signal processing devised from the
signal obtained from this. It is to do.
[0005]
[Means for Solving the Problems] The present invention comprises the following means 1) and 2)
in order to solve the above problems.
That is,
[0006]
1) The directivity axes of the first, second, third and fourth primary bi-directional microphones
are made to be orthogonal to each other on the same plane, and the four primary bi-directional
microphones from the orthogonal point, etc. A microphone device characterized in that it is
disposed at a distance.
[0007]
2) A directivity control apparatus for processing a signal collected by the microphone device
according to claim 1, wherein a target in the horizontal direction with respect to the directivity
axis based on the directivity axis of the first microphone is taken as a reference. When the
rotation angle is θ, the first microphone and the second microphone facing each other across
the directivity axis corresponding to the target rotation angle are combined into one set, and the
first and second microphones A third microphone and a fourth microphone, each located 180
degrees opposite to the microphone, are paired, and the signal collected by the first microphone
is multiplied by COSθ, and the second microphone is used. The collected signals are multiplied
by SINθ, and the multiplied output signals are added together to obtain a first combined
characteristic, while the third microphone The collected signal is multiplied by COS (π + θ), and
the signal collected by the fourth microphone is multiplied by SIN (π + θ), and these multiplied
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output signals are added together to obtain a second synthesized characteristic. And delay the
time corresponding to the sound wave propagation time by the distance between the reference
point of the first synthesis characteristic and the reference point of the second synthesis
characteristic, A directivity control apparatus characterized in that a single second directivity in a
target angular direction is obtained by subtracting a delayed second synthesized signal and an
output signal obtained from the first synthesized characteristic.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present
invention will be described below.
FIG. 1 is a view showing the arrangement of each microphone in the microphone device
according to the embodiment.
In the same figure, M1, M2, M3 and M4 are bi-directional microphones, and the microphones M1
and M2 have their respective directivity axes X and Y orthogonal to each other on the same
plane, and each microphone M1 from its orthogonal point O , M2, M3, and M4 are arranged to
be equal. For example, the directivity characteristics of each of the microphones M1 and M2 are
formed on orthogonal directivity axis X and directivity axis Y orthogonal to each other on the
same plane, respectively, and as shown by reference numerals 20 and 21 in FIG. It is a
characteristic that has been linked.
[0009]
The microphones M3 and M4 are formed on orthogonal directivity axes X and Y orthogonal to
each other on the same plane, and have characteristics as shown by reference numerals 20 'and
21' in FIG. In FIG. 3, although the respective characteristic origins are all shown to coincide with
each other, the characteristic directions and the shape of the characteristic range are simply
illustrated for the purpose of simple illustration, and in actuality, they are shown. The
characteristic origin is far away. Also in the characteristic diagrams thereafter, they are
illustrated with the same purpose.
[0010]
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Here, for example, assuming that the angle from the directivity axis X of the microphone M1 in
FIG. 2 is φ, the directivity characteristic of the microphone M1 is represented by COSφ, and the
directivity characteristic of the microphone M2 is represented by SINφ.
[0011]
Then, with respect to the directivity axis X, let θ be the angle to the target bi-directional
characteristic, and consider directivity in an angle range of 0 ≦ θ ≦ π / 2.
When the output of the microphone M1 is multiplied by COSθ and the output of the microphone
M2 is multiplied by SINθ, their combined characteristics are given by: COSθ × COSφ + SINθ
× SINφ
[0012]
A bi-directionality can be obtained in which the point of origin A is the intersection point A of the
straight line connecting the microphones M1 and M2 in FIG. 2 and the directivity axis P at the
target angle θ. The bi-directionality is, for example, a combined first-order bi-directionality 24
shown as two circles on the directional axis P in FIG.
[0013]
Next, for the combined characteristics of the microphone M3 and the microphone M4, the output
of the microphone M3 is multiplied by COS (π + θ), and the output of the microphone M4 is
multiplied by SIN (π + θ), respectively, and then they are combined. The characteristic is
represented by COS (π + θ) × COSφ + SIN (π + θ) × SINφ. The combining characteristic at
this time is bi-directional, which is the characteristic origin at the intersection point B of the
straight line connecting the microphone M3 and the microphone M4 and the directivity axis P of
the target angle θ. The shape of the bi-directional characteristic is shown as a reference numeral
24 'in FIG.
[0014]
Next, to the combined output of the microphones M3 and M4 obtained as described above, a
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delay corresponding to the sound wave propagation time of the distance between the
characteristic origins A and B of each combined characteristic is added, and thereafter the
combined output of each other The sound from the opposite side of the target directivity
direction becomes substantially identical in phase to each other, the microphones M1 and M2
and the microphones M3 and M4 combined outputs are canceled out, and the sound from the
target directivity direction is An output based on a phase difference corresponding to twice the
sound wave propagation time is obtained, and a single narrow directivity characteristic shown as
symbol 25 in FIG. 4 is obtained.
[0015]
Next, when it is desired to obtain the single narrow directivity characteristic 26 on the directivity
axis Q in FIG. 5 in the angle range of π / 2 <θ ≦ π, the microphone M2 and the microphone
M3 are These combined outputs are obtained as one set, and a combined output is obtained by
combining the microphone M4 and the microphone M1 at a 180 ° opposite position with each
other, and the sound wave propagation time by the distance between both characteristic origins
is obtained in one of them. The single narrow directivity characteristic 26 is obtained by adding a
delay corresponding to and subtracting one from the other.
[0016]
Also, to obtain single narrow directivity characteristics in the angular range of π <θ ≦ 3π / 2
and 3π / 2 <θ <2π, microphone M3 and microphone M4, microphone M1 and microphone
M2, and microphone M4 and microphone It can be determined by performing the same process
as described above with the combination of M1, the microphone M2 and the microphone M3.
[0017]
Here, the arrangement of the microphones M1, M2, M3 and M4 changes the frequency
characteristics due to the sound wave arrival time difference to the microphones according to the
arrival direction of the sound waves and the synthesis bi-directional characteristics in order to
obtain each synthesized bi-directional characteristic. It is better to arrange them close to each
other in consideration of the movement of the origin of the point. However, in order to obtain a
single directional characteristic from the synthetic bi-directional characteristic, the distance
between each synthetic directional characteristic origin is the sensitivity of the single directional
characteristic. Because it is proportional, it will determine the optimal spacing between the
frequency range to be handled and the sensitivity of the final unidirectivity.
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Then, each microphone configured as described above may be attached to the main body of the
video camera by, for example, a known attachment method, or each unit may be housed in a
single housing and used separately. It is possible.
[0018]
Next, with reference to a block diagram shown in FIG. 6, an apparatus for controlling the
directional characteristics of signals obtained from the above-mentioned microphone apparatus
in the target angular direction will be described.
In the figure, the directivity control device is connected to the input terminals 30, 31, 32, and 33
and each of the microphones for inputting output signals output from the microphones, and the
inputs can be switched by control means not shown. In order to multiply coefficients such as
COSθ and SINθ prepared in advance in a table of storage means (not shown) and four input /
output matrix SW circuits (connection lines in SW are omitted because the illustration is
complicated). Multipliers 34, 35, 36, 37, adders 38, 39 for adding the output signals of these
multipliers, and the time (τ) corresponding to the sound wave propagation time by the distance
between the characteristic signal origin of the input signal , And an output terminal 44 for
outputting a signal resulting from the subtraction. That.
[0019]
Next, the operation according to the above configuration will be described.
First, in the case where the target directivity angle is the angle direction of θ as shown in FIG. 4,
for example, control of the angle θ direction is selected in advance by the operation means (not
shown). It is supplied to the means, where the coefficients of COS.theta., SIN.theta., COS (.pi. +.
Theta.) And SIN (.pi. +. Theta.) Are respectively selected from a storage table (not shown) in the
control means.
[0020]
At the same time, a switching signal is supplied from the control means to the matrix SW circuit,
the microphone M1 and the multiplier 34, the microphone M2 and the multiplier 35, the
microphone M3 and the multiplier 36, the microphone M4 and the multiplier 37 And are
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switched to be connected respectively.
[0021]
Then, the signals outputted from the microphones M1, M2, M3 and M4 of the bidirectional
characteristic are respectively supplied to the multipliers 34, 35, 36 and 37 through the matrix
SW circuit, and the above-mentioned preselected signals are input to these input signals.
Coefficients of COSθ, SINθ, COS (π + θ), SIN (π + θ) are supplied and subjected to
multiplication.
[0022]
Next, the signals processed by the multipliers 34 and 35 and the multipliers 36 and 37 are
respectively added by the adders 38 and 39 in the next stage and supplied to one input of the
subtractor 43.
The other composite signal output from the adder 39 is supplied to the delay unit 42 where it is
delayed by a time corresponding to the sound wave propagation time τ due to the distance
between the characteristic origins A and B.
Then, the delayed signal and the combined signal received from one of the above are subtracted
from each other in the subtractor 43, and a signal with a single narrow directivity characteristic
in the direction of the target angle θ is obtained through the output terminal 44. It will be. That
is, the directivity characteristic 25 shown in FIG. 4 is obtained.
[0023]
Further, when it is desired to obtain a single narrow directivity characteristic in the direction as
shown by the directivity characteristic 26 in FIG. 5, the desired direction is selected in advance
by the operation means in the same manner as described above. Based on this, in the control
means, switching control is performed so that the matrix SW circuit includes the microphones
M2 and M3 as a pair and the microphones M4 and M1 as a pair.
[0024]
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That is, the microphone M2 is switched to connect the multiplier 34, the microphone M3 to the
multiplier 35, the microphone M4 to the multiplier 36, and the microphone M1 to the multiplier
37, respectively, and A coefficient is chosen. Then, the signal collected by each microphone is
subjected to the same processing as described above in the control device, and a single narrow
directivity characteristic 26 as shown in FIG. 5 is obtained from the output terminal 44.
[0025]
Next, when it is desired to obtain a single narrow directivity characteristic of 180 degrees
opposite to the directivity characteristic 25 shown in FIG. 4 this time, the desired direction is
selected in advance by the operation means in the same manner as described above. In the
control means, the matrix SW circuit is switched so that the microphones M3 and M4 form one
set and the microphones M1 and M2 form one set. That is, the microphone M3 is switched to
connect the multiplier 34, the microphone M4 is connected to the multiplier 35, the microphone
M1 is connected to the multiplier 36, and the microphone M2 is connected to the multiplier 37,
and the aforementioned predetermined coefficients are selected. .
[0026]
As a result, the combined outputs output from the multipliers 38 and 39 are subtracted from
each other by the subtractor 43, and the single narrow directivity shown by the directivity 25 at
the position of 180 to 270 degrees is obtained from the output terminal 44. It will be obtained.
[0027]
Furthermore, when it is desired to obtain a single narrow directivity characteristic 180 degrees
opposite to the directivity characteristic 26 of FIG. 5, the desired angular direction is selected by
the operation means.
Thus, the matrix SW circuit is a set of microphones M4 and M1, a pair of microphones M2 and
M3, a microphone M4 is a multiplier 34, a microphone M1 is a multiplier 35, a microphone M2
is a multiplier 36, and a microphone M3 is switched to be connected to the multiplier 37
respectively. Also, the above-mentioned predetermined coefficient is selected.
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[0028]
As a result, the same signal processing as described above is performed, and from the output
terminal 44, a single narrow directivity characteristic of 180 degrees opposite to that of the
directivity characteristic 26 of FIG. 5 is obtained. Thus, by selecting the angular direction of the
desired direction by the operation means or the like, a single narrow directivity characteristic of
the same level can be obtained in any direction of 360 degrees in the horizontal direction.
[0029]
As described above, according to the microphone device of this embodiment, the directivity axes
of the four bi-directional microphones are orthogonal to each other in the horizontal plane, and
the microphones are equidistant from the orthogonal point. Due to the arrangement in the above,
and the processing of the directivity control device provided in the latter part, it becomes
possible to obtain the same narrow directivity characteristic of the same level in any direction of
360 degrees in the horizontal direction.
[0030]
Further, according to the directivity control apparatus of the present embodiment, the same
narrow single directivity characteristic can be obtained over an arbitrary angular direction of
360 degrees in the horizontal direction based on the output signal obtained from the microphone
device. .
[0031]
The microphone device and the directivity characteristic control device of the above embodiment
may be directly connected to the front side of the recording processing system on the recording
medium such as the tape provided in the rear part of these devices, and the microphone device
And the directional characteristic control device may be prepared as separate devices.
[0032]
For example, in the case of adopting a VTR-integrated television camera, only the microphone
device is provided on the front side of the recording processing system, and each signal output
from each microphone is recorded as a separate channel, and later edited These separate channel
signals may be reproduced and input to a separately prepared directional characteristic control
device for processing.
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[0033]
According to the microphone device of the first aspect of the invention, it is possible to generate
a signal suitable for controlling the directivity with an extremely simple configuration.
Further, according to the directivity characteristic control device of the second aspect, it is
possible to obtain an effect such that a single narrow directivity characteristic of the same level
can be obtained in any angular direction of 360 degrees in the horizontal direction.
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