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JPH0698390

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DESCRIPTION JPH0698390
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
microphone device capable of picking up sound according to an image in conjunction with a
zooming mechanism such as a video camera or 8 mm camera, and in particular, built in
equipment having an internal noise source and vibration source. The present invention relates to
a microphone device.
[0002]
2. Description of the Related Art In recent years, in order to integrate video and audio with a
video integrated camera, 8 mm camera, etc., a microphone device capable of picking up a sound
in synchronization with the video has been developed. . There are two types of these
conventional microphone devices: monaural type and stereo type.
[0003]
The former monaural type microphone device changes the sound collection angle of the
microphone according to the angle of view of the camera, and is based on the technique of
changing the directivity pattern, and usually outputs of a plurality of directional microphones It
is realized by combining processing. In addition, in order to enhance the zoom effect, a method of
increasing the sensitivity from wide angle to telephoto is generally taken (for example, Japanese
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Patent Publication No. 59-10119). In order to obtain an excellent zoom effect, consistency
between the angle of view and the sound collection angle is required. An example of the angle of
view of the 10 × zoom lens is about 40 degrees at the wide angle and about 4 degrees at the
telephoto. On the other hand, the sound collection angle of the microphone is at most about 100
degrees even in the secondary sound pressure gradient type currently put into practical use as
sharp directivity, and is too wide compared to the angle of view of the zoom lens. Therefore,
there was no expected effect.
[0004]
The latter stereo type microphone device audibly corrects the drawbacks of the monaural type
microphone device, and produces natural zoom effects by adding information on the movement
and direction of the subject. A super-orientation that changes the sound collection angle,
directivity main axis, and sensitivity of the left and right channels according to the angle of view
of the camera and mainly captures stereo sound with rich realism at wide angle and clears the
target sound source at telephoto. It is mainly based on sex collection. Similar to the abovementioned monaural type microphone device, this microphone device is usually realized by
combining the outputs of a plurality of directional microphones (for example, Japanese Patent
Publication No. 60-24636).
[0005]
SUMMARY OF THE INVENTION However, since the conventional microphone apparatus as
described above uses directional microphones such as uni-directionality and bi-directionality, as
described below, a video integrated camera as described below There was a problem to be built
into such devices.
[0006]
When the microphones are roughly classified into nondirectional microphones and directional
microphones, the following characteristics are provided.
An omnidirectional microphone has uniform sound pressure sensitivity frequency characteristics
independent of the direction, distance and frequency of a sound source, and vibration sensitivity
frequency characteristics not dependent on frequency. On the other hand, the directional
microphone changes the sound pressure sensitivity not only by the direction of the sound source
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but also by the distance. That is, when the distance between the sound source and the
microphone approaches, so-called proximity effect causes the sensitivity in the front direction
and the back direction to increase in the bass range. In addition, its vibration characteristics also
become high in the low frequency range. In addition, the sensitivity to the low range is also
increased to the wind.
[0007]
From the above, first of all, in the sound collecting environment where there is no ambient noise,
the directivity of the microphone is generally advantageous if it is sharp. However, as the
distance between the sound source and the microphone approaches, it is necessary to correct the
proximity effect. Next, in a sound collecting environment in which a noise source exists near the
microphone, for example, in a microphone for a built-in video camera, there are noise sources
such as a drive system of a zoom lens and a tape traveling system, and vibration sources. Under
such circumstances, and when the components of these noise sources are concentrated in the
low frequency range, omnidirectional microphones are more advantageous than directional
microphones. Conversely, when the components of the noise source are concentrated in the high
frequency range, the directional microphone is more advantageous than the nondirectional
microphone. Next, when wind is present for outdoor use, a non-directional microphone is
advantageous at least in the low frequency range.
[0008]
As described above, the conventional microphone device having a directional microphone as a
component when it is incorporated in a device such as a video integrated camera having
vibration sources and noise sources inside the device and also used outdoors. There is a problem
that the signal-to-noise ratio of the sound collection is lowered and the sound collection quality is
deteriorated. In particular, in an attempt to sharpen directivity over the entire sound range in
order to improve the zoom effect, on the other hand, there has been a problem that the sound
pickup SN ratio is lowered.
[0009]
In view of the above problems, the present invention is not only capable of collecting a stereo
zoom signal synchronized with an image, but also resistant to noise such as vibration, proximity
noise, and wind, and as a result, a video integrated camera etc. It is an object of the present
invention to provide a microphone device which can be incorporated in a device having a
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vibration source and a noise source inside as described above, and can reduce the size and
weight of the entire device.
[0010]
SUMMARY OF THE INVENTION In order to achieve this object, the microphone device according
to the present invention comprises first and second omnidirectional microphones arranged in a
line in the forward direction with a space between each other; A third omnidirectional
microphone disposed on a vertical bisector of a line connecting the first and second
omnidirectional microphones, and a first phase shifter connected to the first omnidirectional
microphone A second high pass filter connected to the second omnidirectional microphone, a
first high pass filter and a second phase shifter connected to the third omnidirectional
microphone, and a first high pass filter A first subtractor for subtracting the output of the first
phase shifter from the output of the second phase shifter; a second subtractor for subtracting the
output of the second phase shifter from the output of the second high pass filter; Of the first
phase shifter from the output of the high pass filter A third subtractor for subtracting power, a
first equalizer for equalizing the output of the first subtractor, a second equalizer for equalizing
the output of the second subtractor, and an output of the third subtractor A third variable
equalizer for equalizing, a first variable amplifier for changing the output of the first equalizer, a
second variable amplifier for changing the output of the second equalizer, and a variable of
output of the third equalizer A third variable amplifier, a first controller controlling the first and
second variable amplifiers, a second controller controlling the third variable amplifier, and
outputs of the first and third variable amplifiers And a second mixer for mixing the outputs of the
second and third variable amplifiers.
[0011]
Further, it is effective to arrange the main axes of the three nondirectional microphones in
parallel and in the same direction, and fix the three nondirectional microphones so as to
integrally vibrate.
[0012]
According to the present invention, not only the stereo zoom sound pickup synchronized with the
image can be achieved by the above-described configuration, but also the vibration and proximity
noise can be obtained because the low tone region becomes non-directional and the middle and
high tone regions become directivity. It becomes strong against noises such as wind, and as a
result, it becomes possible to incorporate in an apparatus having a vibration source and a noise
source inside, such as a video integrated camera, and it becomes possible to reduce the size and
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weight of the whole apparatus. .
Further, based on stereo sound collection, the directivity of the middle to high range related to
sound image localization can be freely set by the time constant of the phase shifter, so that
effective zoom sound collection is possible.
In addition, since a nondirectional microphone is used, there is almost no variation in sensitivity,
frequency characteristics, directional characteristics, etc., as in the directional microphone, and a
low-cost, stable-quality microphone device can be realized.
Moreover, since a nondirectional microphone is not greatly affected by diffraction or the like like
a directional microphone, it is easy to attach to an apparatus. In addition, it is also possible to
correct the influence of diffraction and the like by a circuit. Furthermore, when the principal axes
of the three nondirectional microphones are arranged in parallel and in the same direction, and
the three nondirectional microphones are fixed so as to vibrate integrally, no directivity is given
to the vibration. It is more advantageous than sex.
[0013]
An embodiment of the present invention will be described below with reference to the drawings.
[0014]
FIG. 1 is a block diagram showing the configuration of a microphone device according to an
embodiment of the present invention.
In FIG. 1, 1 is a first nondirectional microphone, 2 is a second nondirectional microphone
disposed on a straight line in the forward direction with a gap therebetween, 3 is a first
nondirectional microphone 1 and the first nondirectional microphone It is a third nondirectional
myrophone arranged on the perpendicular bisector of the line connecting the two nondirectional
microphones 2. Here, the orientation main axis of the center channel is in the same direction as
the orientation main axis of the microphone device in the direction from the first nondirectional
microphone 1 to the second nondirectional microphone 2. Also, the direction of the directivity
main axis of the stereo right channel is in the direction from the first nondirectional microphone
1 to the third nondirectional microphone 3, and similarly, the direction of the left main channel
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directivity stereo is It is in the direction from the third omnidirectional microphone 3 to the
second omnidirectional microphone 2. Assuming that the angle of viewing the directivity main
axis of the right channel from the directivity main axis of the microphone device is φ, the angle
of viewing the directivity main axis of the left channel from the directivity main axis of the
microphone device is −φ. d1 is the distance between the third nondirectional microphone 3 and
the first nondirectional microphone 1 and the second nondirectional microphone 2, and d2 is the
first nondirectional microphone 1 and the second nondirectional microphone 1 Distance to the
microphone 2. 4 is a first high-pass filter for cutting the bass region upon receiving the output
V3 of the third omnidirectional microphone 3, and 5 is a second high-pass filter for receiving the
output V2 of the second omnidirectional microphone 2 for cutting the bass region , A first phase
shifter for receiving the output V1 of the first omnidirectional microphone 1 and shifting it by
the phase angle .theta.1, a phase angle 7 for receiving the output V3 of the third omnidirectional
microphone 3 a second phase shifter to shift by θ 2, 8 is a first subtractor which subtracts the
output of the first phase shifter 6 from the output of the first high pass filter 4, 9 is an output of
the second high pass filter 5 A second subtractor for subtracting the output of the second phase
shifter 7, 10 is a third subtractor for subtracting the output of the first phase shifter 6 from the
output of the second high pass filter 5, 11 is a third subtractor A first equalizer for equalizing the
output characteristic of the 1 subtractor 8, 12 is a second equalizer The second equalizer 13
equalizes the output characteristic of the subtractor 9, and the third equalizer 13 equalizes the
output characteristic of the third subtractor 10. 14 is a first variable amplifier that changes the
output level of the first equalizer 11, 15 is a second variable amplifier that changes the output
level of the second equalizer 12, and 16 is that which changes the output level of the third
equalizer 13 The third variable amplifier 17 controls the output levels of the first and second
variable amplifiers 14 and 15 to be attenuated continuously in synchronization with the change
of the zoom signal from wide angle to telephoto. The controller 18 is a second controller that
controls the output level of the third variable amplifier 16 to continuously increase in
synchronization with the change of the zoom signal from wide angle to telephoto; 19 is a first
controller A first mixer that mixes the outputs of the third variable amplifiers 14 and 16 and a
second mixer 20 that mixes the outputs of the second and third variable amplifiers 15 and 16.
[0015]
The operation of the microphone device configured as described above will be described below.
[0016]
First, in the middle to high frequency range higher than the cutoff frequency (fC) of the first high
pass filter 4 and the second high pass filter 5, the input signals VR1 and VL1 input to the first
and second variable amplifiers 14 and 15 are The directivity of the microphone device becomes
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directivity from the main axis of angle φ and -φ from the main axis of the microphone device,
the directivity pattern becomes as shown in FIG. 2, and the input signal VC1 entering the third
variable amplifier 16 is the directivity of the microphone device The directivity as the main axis
is obtained, and the directivity pattern is as shown in FIG.
Next, in the bass region lower than the cutoff frequency (fC), the input signals VR1 and VC1 are
only the output V1 of the first nondirectional microphone 1, and the input signal VL1 is the
output of the third nondirectional microphone 3 It becomes V3 only, and VR1, VL1 and VC1
become nondirectional.
[0017]
Also, the output levels VR2 and VL2 of the first and second variable amplifiers 14 and 15 are
controlled by the first controller 17 receiving the zoom signal, and the output level VC2 of the
third variable amplifier 16 receives the zoom signal. Controlled by the second controller 18, VR2
and VL2 and VC2 become as shown in FIG. 5, and in conjunction with the change of the zoom
signal from wide angle to telephoto, VR2 and VL2 are continuously attenuated and the telephoto
end And VC2 increases continuously and becomes maximum at the telephoto end. Finally, the
output signal VR2 of the first variable amplifier 14 and the output signal VC2 of the third
variable amplifier 16 are mixed in the first mixer 19, and the output signal VR becomes the right
channel output, and the second variable amplifier 15 The output signal VL2 of the third variable
amplifier 16 and the output signal VC2 of the third variable amplifier 16 are mixed in the second
mixer 20, and the output signal VL is the left channel output, and the directivity patterns of the
output signals VR and VL of each channel are In conjunction with the change from the wide
angle to the telephoto of the zoom signal, the state changes from FIG. 2 to FIG. 3 to FIG. In the
figure, the solid line is the directivity pattern of the right channel, and the dotted line is the
directivity pattern of the left channel. Thus, at the wide-angle end of the camera signal, the
directivity main axes of the outputs VR and VL of the right and left channels are opened by φ
and -φ, and the directivity of VR and VL is interlocked with the change of the camera signal to
telephoto. The dynamic principal axis also gradually changes in the direction of the directivity
principal axis of the microphone device, and at the telephoto end of the camera signal, the
directivity principal axis of VR and VL becomes the same, and overlaps with the directivity
principal axis of the microphone device. .
[0018]
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As described above, according to the present embodiment, not only is it possible to pick up a
stereo zoom synchronized with the image, but also the non-directivity in the low range and the
directivity in the middle and high range, so vibration and proximity noise It becomes strong
against noises such as wind, and as a result, it becomes possible to incorporate it into equipment
that has vibration source and noise source inside like a video integrated camera etc., and it is
possible to make these equipments smaller and lighter. Become. Moreover, the directivity of the
middle to high range related to the sound image localization of the center channel and each
stereo channel can be freely set by the time constant of the phase shifter, and furthermore, the
directivity main axis (φ, Since −φ) can be freely set by the arrangement of the third
nondirectional microphone 3, effective zoom sound collection is possible. In addition, since a
nondirectional microphone is used, there is almost no variation in sensitivity, frequency
characteristics, directional characteristics, etc., as in the directional microphone, and a low-cost,
stable-quality microphone device can be realized. Moreover, since a nondirectional microphone is
not greatly affected by diffraction or the like like a directional microphone, it is easy to attach to
an apparatus. In addition, it is also possible to correct the influence of diffraction and the like by
a circuit.
[0019]
Also, as shown in FIG. 1, if the main axes of the three nondirectional microphones are arranged in
parallel and in the same direction, and the three nondirectional microphones are fixed so as to
vibrate integrally, the center channel and In the directivity regions of middle and high frequency
ranges of the left and right channels, the attenuation of the sound pressure sensitivity in the 90degree direction with respect to the 0-degree direction about each directivity main axis is
advantageous over the non-directivity with respect to vibration.
[0020]
Although two phase shifters are used in this embodiment, a delay may be used instead of this
phase shifter.
[0021]
As described above, according to the present invention, the first and second nondirectional
microphones and the first and second nondirectional microphones arranged in a straight line in
the forward direction with a space therebetween are provided. Connected to the third
omnidirectional microphone disposed on the perpendicular bisector of the connecting line
segment, the first phase shifter connected to the first omnidirectional microphone, and the
second omnidirectional microphone A second high pass filter, a first high pass filter and a second
phase shifter connected to a third omnidirectional microphone, and an output of the first high
pass filter from the output of the first high pass filter A first subtractor for subtracting the
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output, a second subtractor for subtracting the output of the second phase shifter from the
output of the second high pass filter, and a first transfer from the output of the second high pass
filter A third subtractor for subtracting the output of the phaser, and a first subtractor The first
equalizer that equalizes the output, the second equalizer that equalizes the output of the second
subtractor, the third equalizer that equalizes the output of the third subtractor, and the variable
output of the first equalizer Control the first variable amplifier, the second variable amplifier that
changes the output of the second equalizer, the third variable amplifier that changes the output
of the third equalizer, and the first and second variable amplifiers , A second controller for
controlling a third variable amplifier, a first mixer for mixing the outputs of the first and third
variable amplifiers, and a second and third variable controller The configuration of the second
mixer that mixes the output of the amplifier and the omnidirectional low-pitched sound area and
the directivity of middle-high range are not only capable of collecting stereo zoom sound
synchronized with the image, Against noise such as vibration, proximity noise, wind Even
stronger, so that the built-in equipment having a vibration source and noise source therein, such
as camcorders become available, size and weight of the entire these devices is possible.
[0022]
Furthermore, since the main axes of the three nondirectional microphones are arranged in
parallel and in the same direction, and the three nondirectional microphones are fixed so as to
integrally vibrate, they are also resistant to vibration.
As described above, the present invention has significant practical effects.
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