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JPH05260585

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DESCRIPTION JPH05260585
[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 a noise source and a vibration source inside. 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 employed. (For example, see
Japanese Patent Publication No. 59-10119). In order to obtain an excellent zoom effect,
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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 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 each 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 presence at the wide angle and clearly
collects the target sound source at the telephoto. It is mainly based on sex collection. Similar to
the above-mentioned 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 sense of sound pressure not only by the direction of the sound source
but also by the distance. That is, when the distance between the sound source and the
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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, in a sound collecting environment where ambient noise does not exist, it is
generally advantageous that the directivity of the microphone be 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. On the contrary, when the component of the noise source is 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, when incorporated in a device such as a video integrated camera that has a
vibration source and a noise source inside the device and is also used outdoors, a conventional
microphone having a directional microphone as a component The device has 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 picking up a zoom
signal synchronized with an image, but is also resistant to noise such as vibration, proximity
noise, and wind, and as a result, as in a video integrated camera etc. An object of the present
invention is to provide a microphone device which can be internally provided to a device having
a vibration source and a noise source, and can reduce the size and weight of the entire device.
03-05-2019
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[0010]
SUMMARY OF THE INVENTION In order to achieve this object, the microphone device of the
present invention comprises first and second nondirectional microphones arranged in a straight
line at intervals from each other; Connected to the third and fourth nondirectional microphones
and the first nondirectional microphone, which are arranged on a straight line spaced apart from
each other on the vertical bisector of the line connecting the second nondirectional microphone
A second phase shifter connected to the second omnidirectional microphone, a first high pass
filter connected to the third omnidirectional microphone, and a fourth phase shifter connected to
the second omnidirectional microphone; A third phase shifter connected to the omnidirectional
microphone, a first subtractor for subtracting the output of the first phase shifter from the output
of the first high pass filter, and an output of the first high pass filter A second subtractor for
subtracting the output of the second phase shifter; A third subtractor that subtracts the output of
the third phase shifter from the output of the three nondirectional microphones, a first equalizer
that equalizes the output of the first subtractor, and an output of the second subtractor , A third
equalizer equalizing the output of the third subtractor, a second high pass filter for cutting the
bass of the output of the third equalizer, and an output of the first equalizer , A second variable
amplifier for changing the output of the second equalizer, a third variable amplifier for changing
the output of the second high-pass filter, and a first and a second variable A first controller for
controlling the amplifier, a second controller for controlling the third variable amplifier, and a
first mixer for mixing the outputs of the first and third variable amplifiers Second mixer to mix
the outputs of the three variable amplifiers It is those with a.
[0011]
In the present invention, with the above-described configuration, the bass region is
nondirectional when the zoom signal is wide-angle, the middle-high range is directional when the
zoom signal is wide, and the bass region is cut when the zoom signal is telephoto. It becomes
strong against noise and noise 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 reduce the size and weight of the whole equipment. It becomes.
[0012]
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.
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In addition, since a nondirectional microphone is used, there is almost no variation in sensitivity,
frequency characteristics, directional characteristics, etc., as in a 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.
[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
arranged in a straight line with a distance from it, 3 is a first nondirectional microphone 1 and a
second nondirectional microphone. A third omnidirectional microphone disposed on the vertical
bisector of the line connecting the directional microphones 2, 4 is a straight line on the same
vertical bisector and at a distance from the third omnidirectional microphone 3. It is a 4th
nondirectional microphone arrange | positioned on a line. Here, the direction of the directivity
main axis of the center channel is in the same direction as the directivity main axis of the
microphone device in the direction from the fourth nondirectional microphone 4 to the third
nondirectional microphone 3. Also, the direction of the directivity main axis of the stereo right
channel is in the direction from the second nondirectional microphone 2 to the third
nondirectional microphone 3, and similarly, the direction of the left main channel directivity
stereo is It is in the direction from the first nondirectional microphone 1 to the third
nondirectional microphone 3. 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 third
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nondirectional microphone 3 and the fourth nondirectional microphone Distance to the
microphone 4. 5 is a first high-pass filter for cutting the bass region upon receiving the output
V3 of the third nondirectional microphone 3; 6 is a first high-pass filter for receiving the output
V1 of the first nondirectional microphone 1; Of the second omnidirectional microphone 2
receives the output V2 of the second omnidirectional microphone 2 and shifts it by the phase
angle .theta. 2; 8 receives the output V4 of the fourth omnidirectional microphone 4 and shifts
the phase A third phase shifter to shift by an angle θ 3, a first subtractor 9 that subtracts the
output of the first phase shifter 6 from an output of the first high pass filter 5, and an output of
the first high pass filter 10. Subtractor for subtracting the output of the second phase shifter 7
from the second subtractor 11, and third subtractor for subtracting the output of the third phase
shifter 8 from the output V3 of the third omnidirectional microphone 3 , 12 is a first equalizer
for equalizing the output characteristic of the first subtractor 9, 13 is a second subtractor The
second equalizer 14 equalizes the output characteristic of 0, the third equalizer 14 equalizes the
output characteristic of the third subtractor 11, and the second 15 cuts the bass region upon
receiving the output of the third equalizer 14 High pass filter.
The first variable amplifier 16 changes the output level of the first equalizer 12, the second
variable amplifier 17 changes the output level of the second equalizer 13, and the output level of
the second high-pass filter 15. The variable third variable amplifier 19 controls the output levels
of the first and second variable amplifiers 16 and 17 to be attenuated continuously in
synchronization with the change of the zoom signal from wide angle to telephoto. Is a second
controller for controlling the output level of the third variable amplifier 18 to be continuously
increased in synchronization with the change of the zoom signal from wide angle to telephoto; , A
first mixer for mixing the outputs of the third variable amplifiers 16 and 18, and a second mixer
22 for mixing the outputs of the second and third variable amplifiers 17 and 18.
[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 5, the input signals VL1 and VR1 entering the first and second variable amplifiers 16
and 17 are from the directivity main axis of the microphone device The directivity with the
direction of the angles φ and −φ as the main axis is obtained, and the directivity pattern is as
shown in FIG.
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Further, in the bass region lower than the cut-off frequency (fc), the output V3 of the microphone
3 is cut and only the outputs V1 and V2 of the microphones 1 and 2 are present, and both VL1
and VR1 become nondirectional. Next, the input signal VC1 entering the third variable amplifier
18 has directivity as the directivity main axis of the microphone device, and its directivity pattern
is as shown in FIG.
[0017]
The output levels VL2 and VR2 of the first and second variable amplifiers 16 and 17 are
controlled by the first controller 19 which receives the zoom signal, and the output level VC2 of
the third variable amplifier 18 receives the zoom signal. Controlled by the second controller 20,
and VL2, VR2 and VC2 become as shown in FIG. 5, and in conjunction with the change of the
zoom signal from wide angle to telephoto, VL2 and VR2 are continuously attenuated and the
telephoto end , And VC2 increases continuously and becomes maximum at the telephoto end.
Finally, the output signal VL2 of the first variable amplifier 16 and the output signal VC2 of the
third variable amplifier 18 are mixed by the first mixer 21, and the output signal VL becomes the
left channel output, and the second variable amplifier 17 The output signal VR2 of the third
variable amplifier 18 and the output signal VC2 of the third variable amplifier 18 are mixed by
the second mixer 22, and the output signal VR becomes the right channel output, and the
directivity pattern of the output signals VL and VR of each channel is 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
mamela signal, the directivity main axes of the outputs VL and VR of the left and right channels
are open by φ and -φ, and the directivity of VL and VR is interlocked with the change of the
camera signal to telephoto. The main axis also gradually changes in the direction of the
directional main axis of the microphone device, and at the telephoto end of the camera signal, the
directional main axes of VL and VR become the same, and overlap with the directional main axis
of the microphone device.
[0018]
As described above, according to the present embodiment, the bass region is nondirectional
when the zoom signal is wide-angle, the middle and high frequency regions become directivity
when the zoom signal is telescopic, and the bass region is cut when the zoom signal is telescopic.
It becomes strong against noise and noise such as wind, and as a result, it becomes possible to
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incorporate it into equipment that has vibration source and noise source inside like a video
integrated camera etc., and it is possible to reduce the size and weight of the whole equipment. It
becomes. Further, since the directivity of the center channel and the directivity of middle to high
frequency bands related to the sound image localization of each stereo channel can be freely set
by the time constant of the phase shifter, effective zoom sound pickup is possible. In addition,
since a nondirectional microphone is used, there is almost no variation in sensitivity, frequency
characteristics, directivity characteristics, etc., as in the directional microphone, and a
microphone device with stable quality can be realized at low cost. 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, when the microphone device is built
in a device such as a video integrated camera or an 8 mm camera, generally the structure of the
device is not symmetrical left and right, so it is affected by different diffractions in the left and
right channels. By individually setting the time constants of the phase shifters connected to the
circuit, it is possible to correct the effects of diffraction and the like in the circuit for each
channel. Also, if the main axes of the four nondirectional microphones are arranged in parallel
and in the same direction as shown in FIG. 1 and the four nondirectional microphones are fixed
so as to integrally vibrate, the directivity of the center channel In the area and in the directivity
areas of the middle and upper ranges of the left and right channels, the attenuation of the sound
pressure sensitivity in the 90 ° direction with respect to the 0 ° direction with each directivity
main axis as an advantage over the nondirectivity against vibration Become. Although three
phase shifters are used in this embodiment, a delay may be used instead of the phase shifters.
[0019]
Moreover, in the present embodiment, the fourth nondirectional microphone is disposed behind
the third nondirectional microphone, but similar results can be obtained even if the arrangement
is changed as follows. That is, the fourth nondirectional microphone is disposed behind the first
nondirectional microphone by a distance d2, and the connection between the third
nondirectional microphone and the third subtractor is deleted, The output of the one
omnidirectional microphone may be connected to the first phase shifter and the third subtractor.
Alternatively, the fourth omnidirectional microphone may be disposed behind the second
omnidirectional microphone. This has the merit that, in the case where the microphone device is
incorporated in a device such as a video integrated camera or an 8 mm camera, changes in
design can be coped with in relation to other components.
[0020]
As described above, according to the present invention, a line connecting the first and second
nondirectional microphones, which are arranged on a straight line at a distance from each other,
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and the first and second nondirectional microphones. Third and fourth nondirectional
microphones arranged in a straight line at an interval on the outside of the vertical bisector of a
minute and a first phase shifter connected to the first nondirectional microphone; , A second
phase shifter connected to the second omnidirectional microphone, a first high pass filter
connected to the third omnidirectional microphone, and a second phase shifter connected to the
fourth omnidirectional microphone The third phase shifter, a first subtractor for subtracting the
output of the first phase shifter from the output of the first high pass filter, and the output of the
second phase shifter from the output of the first high pass filter A second subtractor to subtract,
and a third from the output of the third omnidirectional microphone A third subtractor for
subtracting the output of the phaser, a first equalizer for equalizing the output of the first
subtractor, a second equalizer for equalizing the output of the second subtractor, and a third
subtraction A second equalizer for equalizing the output of the first equalizer, a second high pass
filter for cutting the bass range of the output of the third equalizer, a first variable amplifier for
varying the output of the first equalizer, and A second variable amplifier that changes the output
of the equalizer, a third variable amplifier that changes the output of the second high pass filter,
a first controller that controls the first and second variable amplifiers, and a third A second
controller for controlling the variable amplifiers, a first mixer for mixing the outputs of the first
and third variable amplifiers, and a second mixing for mixing the outputs of the second and third
variable amplifiers In the wide-angle range of the zoom signal. Mid- and high-pitched regions
become directional with no directivity, and the bass region is cut off at the time of telephoto of
the zoom signal, so it is possible not only to be able to collect stereo zoom sound synchronized
with the image but also vibration, proximity noise, wind Against noise, etc. As a result, it can be
incorporated in an apparatus having a vibration source or a noise source inside, such as a video
integrated camera, and the whole can be made smaller and lighter.
[0021]
As described above, the present invention has significant practical effects.
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