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JP2001028795

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DESCRIPTION JP2001028795
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
zoom microphone capable of switching between sound collection in a wide angle range and
sound collection in a narrow angle range.
[0002]
In general, to switch the directivity of a stereo microphone that picks up sound in a recording /
reproducing device such as a portable MD or a video camera etc. in order to record distant
voices. Some have a zoom function that can
[0003]
FIG. 4 is a block diagram showing the structure of a conventional zoom microphone described in
Japanese Patent Laid-Open No. 10-79877.
In FIG. 4, the zoom microphone 1 includes an L-side microphone 2 a, an R-side microphone 2 b,
an L-side delay circuit 3 a, an R-side delay circuit 3 b, and a zoom processing circuit 4. The zoom
position signal α is input from the drive circuit 5 of FIG.
[0004]
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1
The zoom microphone 1 picks up sound with the L-side microphone 2a and the R-side
microphone 2b facing in the same direction, and inputs the audio signals l and r to the zoom
processing circuit 4, respectively. The audio signals l and r from the L-side microphone 2a and
the R-side microphone 2b are input to the L-side delay circuit 3a and the R-side delay circuit 3b,
respectively, and are respectively generated by the L-side delay circuit 3a and the R-side delay
circuit 3b. The audio signals l 'and r' delayed by the required time are input to the zoom
processing circuit 4.
[0005]
The zoom processing circuit 4 subtracts the audio signal r 'of the output of the R-side delay
circuit 3b from the audio signal l of the L-side microphone 2a to output an audio signal l ", and
outputs the audio signal of the R-side microphone 2b. The audio signal l 'at the output of the Lside delay circuit 3a is subtracted from the signal r to output an audio signal r ".
[0006]
At this time, the zoom processing circuit 4 analyzes the zoom position signal α input from the
lens drive circuit 5, and the L side and the R side are determined based on the zoom position of
the lens indicated by the zoom position signal α. By changing the subtraction ratio of each audio
signal in, the sound collection in the wide angle range and the sound collection in the narrow
angle range are switched.
[0007]
That is, when the zoom position signal α indicates that the lens is positioned at the wide angle
side, the zoom processing circuit 4 increases the subtraction ratio in the zoom processing circuit
4 to set the L side and the R side. By canceling the required signal on the side, the pseudo stereo
audio signals l "and r" different from each other are output.
[0008]
Further, when the zoom position signal α indicates that the lens is positioned at the narrow
angle side, the subtraction ratio in the zoom processing circuit 4 is decreased to make the L side
microphone 2a and the R side microphone The audio signals l and r from 2b are output as audio
signals l "and r" as they are.
[0009]
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At this time, since the L-side microphone 2a and the R-side microphone 2b face in the same
direction, the audio signals l "and r" are substantially the same signal, whereby the outputs of the
audio signals l "and r" are It becomes an output of a monaural audio signal in a pseudo manner.
[0010]
As described above, the conventional zoom microphone 1 pseudo-appears the zoom function of
the microphone by changing the subtraction ratio in the zoom processing circuit 4 in accordance
with the lens position from the wide angle to the narrow angle. It is supposed to
[0011]
However, this conventional zoom microphone needs to have many active elements such as delay
circuits connected to the L-side and R-side microphones, and a zoom processing circuit for
subtracting an audio signal, and further, Since each of these active elements requires a power
supply, the structure of the microphone becomes complicated and large-sized, and further, there
is a problem that a so-called plug-in type can not be constructed. .
[0012]
The present invention has been made to solve the problems of the conventional zoom
microphones as described above.
That is, the object of the present invention is to provide a zoom microphone which can be
simplified in configuration, miniaturized, and configured as a so-called plug-in type.
[0013]
According to a first aspect of the present invention, there is provided a zoom microphone
according to the first aspect of the present invention, which comprises: a first microphone and a
second microphone disposed in parallel to a sound collecting surface; Between the third
microphone disposed between the first microphone and the second microphone, the first output
terminal connected to the first microphone, and the second output terminal connected to the
second microphone, and to the third microphone A zoom mode in which an audio signal from the
first microphone, an audio signal from the second microphone, and an audio signal obtained by
combining an audio signal from the third microphone are output from the first output terminal
and the second output terminal; Disconnecting the connection between the microphone and the
first output terminal and the second output terminal It is characterized in that it comprises: a
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3
composite output circuit which is switched between a stereo mode in which an audio signal is
output from a first output terminal and an audio signal from a second microphone is output from
a second output terminal.
[0014]
The zoom microphone according to the first aspect of the present invention is used by being
connected to a recording / reproducing apparatus such as a portable MD, a video camera or the
like, and when collecting sound in a narrow angle range, the synthesis output circuit is in the
zoom mode. When being switched and collecting sound in the wide angle range, the synthesis
output circuit is switched to the stereo mode.
[0015]
Thus, in the zoom mode, the combined output circuit combines the voice signal from the first
microphone, the voice signal from the second microphone, and the voice signal from the third
microphone, and the combined voice signal. Are outputted from the first output terminal and the
second output terminal, respectively, whereby the zoom sound pickup in the narrow angle range
is performed.
[0016]
In the stereo mode, the synthesis output circuit cuts off the connection between the third
microphone and the first output terminal and the second output terminal, and the synthesis of
the audio signals from the respective microphones is not performed. The audio signal from the
microphone is output from the first output terminal, and the audio signal from the second
microphone is output from the second output terminal, so that stereo sound collection in the
wide-angle range is performed.
[0017]
As described above, according to the first aspect of the present invention, it is possible to
perform the zoom sound collection in which sound collection is performed in the narrow angle
range and the stereo sound collection in which sound collection is performed in the wide angle
region As a result, it is possible to provide a compact zoom microphone having a simple
configuration, and by using the first output terminal as one of the terminal portions of the plug
and the second output terminal as the other terminal of the plug. The configuration is also
possible as a so-called plug-in type.
[0018]
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4
In the zoom microphone according to a second aspect of the present invention, in addition to the
configuration of the first aspect of the present invention, in addition to the configuration of the
first aspect, the combined output circuit is connected between the first and second output
terminals. To the reference potential via the first and second resistors connected in series, the
first terminal connected to the third microphone, and the second terminal connected between the
first and second resistors, a capacitor It has a third terminal connected, and has a switch to be
switched to a zoom mode position connecting the first terminal and the second terminal, and a
stereo mode position connecting the second terminal and the third terminal. It is characterized.
[0019]
In the zoom microphone according to the second aspect of the present invention, at the time of
the zoom mode, the changeover switch is switched to the position where the first terminal and
the second terminal are connected, and the third microphone is between the first resistance and
the second resistance. Connected, the connection between the first and second resistors and the
capacitor is disconnected.
[0020]
Thus, in the zoom mode, the audio signal from the third microphone flows to the first terminal
through one of the resistors, and the audio signal from the second microphone through the first
resistor and the second resistor. The audio signals from the second and third microphones are
combined with the audio signal from the first microphone, and similarly, the audio signal from
the third microphone flows to the second terminal through the other resistor. At the same time,
an audio signal from the first microphone flows through the first resistor and the second resistor,
and audio signals from the first and third microphones are combined with an audio signal from
the second microphone.
[0021]
Then, in the stereo mode, the changeover switch is switched to a position connecting the second
terminal and the third terminal, whereby the connection between the third microphone and the
first resistor and the second resistor is disconnected, Instead, the first and second resistors are
connected to the reference potential via a capacitor.
[0022]
As a result, audio signals output from the first microphone and the second microphone and
flowing to the first output terminal side or the second output terminal side through the first
resistance and the second resistance, respectively, are connected in series. It is filtered by the
LPF constituted by the first resistor or the second resistor and the capacitor to be arranged, and
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only an audio signal of several Hz or less can pass to the first output terminal side or the second
output terminal side.
[0023]
Since such a voice signal of several Hz or less is not picked up by the first and second
microphones, the voice signal outputted from the first output terminal is only the voice signal
from the first microphone. Similarly, the audio signal output from the second output terminal is
only the audio signal from the second microphone.
[0024]
As described above, according to the first aspect of the present invention, the changeover switch
can be switched manually, and the circuit element constituting the synthesis output circuit for
synthesizing the audio signal is the power supply circuit of its own. This makes it possible to
provide a compact zoom microphone with a simple configuration.
[0025]
In a zoom microphone according to a third invention, in order to achieve the above object, in
addition to the configuration of the first invention, the first microphone, the second microphone,
and the third microphone have single directivity. It is characterized by being a microphone.
[0026]
According to the zoom microphone of the third aspect of the present invention, the first
microphone, the second microphone, and the third microphone all have unidirectionality, so that
it is possible to collect in the narrow angle range in the zoom mode. Sound and sound collection
in the wide angle range in the stereo mode can be reliably performed.
[0027]
In the zoom microphone according to the fourth invention, in order to achieve the above object,
in addition to the configuration of the first invention, the first output terminal is one of the
terminal parts of the plug, and the second output is a second output. The terminal is the other
terminal of the plug.
[0028]
According to the fourth invention, it is possible to provide a plug-in type zoom microphone, and
it is easy to insert a plug into the jack of a recording / reproducing apparatus such as a portable
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MD or a video camera etc. Will be able to connect to
[0029]
In order to achieve the above object, the zoom microphone according to the fifth invention is
characterized in that, in addition to the configuration of the fourth invention, the plug has a
configuration of plug-in power. .
[0030]
According to the fifth aspect of the invention, the power necessary for driving the first to third
microphones is supplied from the power supply of the recording / reproducing device to which
the zoom microphone is connected or the set main body such as a video camera. The zoom
microphone itself does not have to be provided with a power supply unit, which makes it possible
to provide a compact and lightweight zoom microphone.
[0031]
BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the most preferable embodiment
of the present invention will be described in detail with reference to the drawings.
[0032]
FIG. 1 is a block diagram showing an example of an embodiment of a zoom microphone
according to the present invention.
In FIG. 1, the zoom microphone 10 is a so-called plug-in power type zoom microphone, and is
connected to a recording / reproducing apparatus such as a portable MD or a video camera by a
plug-in plug P.
[0033]
The zoom microphone 10 includes an Lch microphone 11L and an Rch microphone 11R, and
further includes a center microphone 11S disposed at an intermediate position between the Lch
microphone 11L and the Rch microphone 11R.
[0034]
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The Lch microphone 11L and the Rch microphone 11R and the center microphone 11S are both
condenser microphones, and are driven by a DC voltage supplied from a set main body to which
the zoom microphone 10 is connected, as described later. It has become.
[0035]
The Lch microphone 11L is connected to the L terminal portion P1 of the insertion plug P by the
wiring a, and the Rch microphone 11R is connected to the R terminal portion Pr of the insertion
plug P by the wiring b.
The wiring a of the Lch microphone 11L and the wiring b of the Rch microphone 11R are
connected to each other through resistors R1 and R2 arranged in series from the wiring a side.
[0036]
Connected to the center microphone 11S is a changeover switch SW connected to the connection
of the resistors R1 and R2.
The changeover switch SW includes a microphone side terminal s1 to which the center
microphone 11S is connected, a resistance side terminal s2 connected to a connection portion
between the resistors R1 and R2, and a ground terminal s3 connected to a reference potential via
a capacitor C. , And by sliding the mover s4, the microphone side terminal s1 and the resistance
side terminal s2, and the resistance side terminal s2 and the earth terminal s3 are switched and
connected (FIG. 1 shows A state is shown in which the microphone side terminal s1 and the
resistance side terminal s2 are connected by the mover s4).
[0037]
Next, the operation of the zoom microphone 10 will be described.
[0038]
The zoom microphone 10 is connected to a recording / reproducing apparatus such as a portable
MD or the like, a set body such as a video camera by inserting the plug P into a jack provided on
the set body. The Lch microphone 11L, the Rch microphone 11R, and the center microphone 11S
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are driven by the application of the DC voltage supplied from the power supply circuit of the set
main body via the.
[0039]
Then, in the zoom mode in which sound is collected in the narrow angle range, the mover s4 of
the changeover switch SW is switched to the position where the microphone side terminal s1 and
the resistance side terminal s2 are connected, whereby the center microphone 11S is resistance
It is connected to the connection of R1 and R2, and the connection between the resistors R1 and
R2 and the capacitor C is disconnected.
[0040]
Thus, the audio signals input to the L terminal portion P1 and the R terminal portion Pr of the
insertion plug P in the zoom mode are respectively output from the Lch microphone 11L, the Rch
microphone 11R, and the center microphone 11S. The audio signals are synthesized with one
another via the resistors R1 and R2.
[0041]
At this time, with regard to the audio signal (hereinafter referred to as L-ch output) inputted to
the L terminal portion P1 of the insertion plug P, the load resistance of each microphone is Lch
microphone 11L: The zoom microphone 10 is connected The impedance (Ro) center microphone
11S of the power supply circuit of the set main body: Ro + R1 Rch microphone 11R: Ro + R1 +
R2.
[0042]
The same applies to the audio signal (hereinafter referred to as R-ch output) input to the R
terminal portion Pr of the plug-in plug P.
At this time, in this example, the relationship between the respective impedances is Ro (10
K.OMEGA.) >> R1 (1 K.OMEGA.) And R2 (1 K.OMEGA.).
[0043]
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As described above, in this zoom mode, the L-ch output and the R-ch output input to the L
terminal portion P1 and the R terminal portion Pr of the insertion plug P are all three
microphones. The sound signal from the multi-microphone output is substantially combined, and
the front sensitivity of the zoom microphone 10 has the directivity of the zoom as shown in FIG.
At this time, the sensitivity in the rotational direction of the zoom microphone 10 is canceled by
the phase relationship.
[0044]
On the other hand, in the stereo mode in which sound is collected in the wide angle range, the
mover s4 of the changeover switch SW is switched to the position where the resistor side
terminal s2 and the ground terminal s3 are connected, thereby making the center microphone
11S and the resistor R1 and The connection between R2 and R2 is disconnected, and the
resistors R1 and R2 are connected to the reference potential via the capacitor C.
[0045]
Thus, an audio signal output from the Rch microphone 11R and flowing to the wire a through the
resistor R2 is filtered by the LPF constituted by the resistor R2 and the capacitor C in series, Only
the following audio signals can not pass to the wiring a side.
The same applies to an audio signal that is output from the Lch microphone 11L and is going to
flow to the wiring b side via the resistor R1.
[0046]
Since such audio signals of several Hz or less are not picked up by each microphone, in this
stereo mode, the audio signals input to the L terminal portion P1 of the insertion plug P are Lch
microphones 11L. The audio signal input to the R terminal Pr is only the audio signal from the
Rch microphone 11R, and the front sensitivity of the zoom microphone 10 is stereo directivity as
shown in FIG. It will be possessed.
[0047]
Brief description of the drawings
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[0048]
1 is a circuit diagram showing an example of an embodiment of the present invention.
[0049]
2 is an explanatory view showing the directivity of the microphone in the zoom mode in the same
example.
[0050]
3 is an explanatory view showing the directivity of the microphone in the stereo mode in the
same example.
[0051]
4 is a block diagram showing a conventional example.
[0052]
Explanation of sign
[0053]
10: Zoom microphone 11L: Lch microphone (first microphone) 11R: Rch microphone (second
microphone) 11S: center microphone (third microphone) R1: resistance (first resistance) R2:
resistance (second resistance) SW: switching Switch s1 ... microphone side terminal (first
terminal) s2 ... resistance side terminal (second terminal) s3 ... earth terminal (third terminal) s4 ...
mover C ... capacitor P ... plug P1 ... L terminal portion Pr ... R Terminal
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