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JPH09182185

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Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
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DESCRIPTION JPH09182185
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
audio recording apparatus, and more particularly to an audio recording apparatus which selects
and uses a plurality of microphone units.
[0002]
2. Description of the Related Art In the prior art, various technical means for connecting and
using an external microphone unit in addition to the built-in microphone unit in a voice recording
and reproducing apparatus are known, and an example thereof will be described with reference
to the drawings. .
[0003]
FIG. 7 is an electric circuit diagram showing an example of an audio recording unit in a
conventional audio recording and reproducing apparatus.
[0004]
As shown in the figure, the audio recording and reproducing apparatus includes a built-in
microphone unit 1 and a microphone jack 2 to which an external microphone unit is connected.
01-05-2019
1
The built-in microphone unit 1 adopts an electret condenser microphone unit, the negative
terminal is connected to GND, the positive terminal is connected to the fixed piece of the
microphone jack 2, and the resistor R3 and the resistor R1 are connected via the resistor R1. It is
connected to the connection point of the capacitor C1.
The other end of the resistor R3 is connected to the power supply + Vcc, and the other end of the
capacitor C1 is connected to GND. The resistor R3 and the capacitor C1 constitute a ripple filter
for the power supply + Vcc.
[0005]
On the other hand, the movable piece of the microphone jack 2 is connected to the connection
point of the resistors R1 and R3 and the capacitor C1 via the resistor R2 and to the input end of
the preamplifier 3 via the capacitor C2. The ground piece of the microphone jack 2 is connected
to GND.
[0006]
Next, the operation of the audio recording and reproducing apparatus having such a
configuration will be described.
[0007]
First, an audio recording operation by the built-in microphone unit 1 will be described with
reference to FIG.
[0008]
FIG. 8 is an equivalent circuit of the main part of the audio recording and reproducing apparatus,
and shows a state in which an external microphone unit is not connected to the microphone jack
2.
[0009]
As shown in FIG. 8, when the external microphone unit is not connected to the microphone jack
2, the movable piece and the fixed piece of the microphone jack 2 are in contact with each other,
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2
so the positive terminal of the built-in microphone unit 1 has a resistance It is connected to the
connection point B between R2 and the capacitor C2.
Therefore, the resistors R1 and R2 are connected in parallel.
[0010]
Here, assuming that a point passing through the ripple filter from the power supply + Vcc
through the resistor R3 and the capacitor C1 is a point A, a direct current is supplied from this
point A to the plus terminal of the built-in microphone unit 1 via the resistor R1 and the resistor
R2. At the same time, the parallel combined resistor of the resistor R1 and the resistor R2 is the
load resistor of the built-in microphone unit 1.
[0011]
The sound input to the built-in microphone unit 1 is converted into an electric signal and appears
at the plus terminal of the built-in microphone unit 1.
Since the movable piece and the fixed piece of the microphone jack 2 are connected as described
above, the same signal appears at the point B which is a connection point between the resistor
R2 and the capacitor C2.
This is transmitted to the input of the preamplifier 3 through the capacitor C2.
[0012]
FIG. 9 is an equivalent circuit of the voice recording and reproducing apparatus shown in FIG. 7
and shows a state in which an external microphone unit is connected to the microphone jack.
[0013]
As shown in FIG. 9, when the external microphone unit 10 is connected to the microphone jack 2,
the movable piece of the microphone jack 2 moves away from the fixed piece.
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3
As a result, the plus terminal of the built-in microphone unit 1 is not connected to the point B.
Also, the plus terminal of the external microphone unit 10 is connected to the point B, and the
minus terminal of the external microphone unit 10 is connected to the GND. Therefore, current is
supplied from the point A to the plus terminal of the external microphone unit 10 through the
resistor R2, and the sound converted into an electrical signal is changed to the point B in the
same manner as described above for the built-in microphone unit 1. It will appear.
[0014]
If the built-in microphone unit 1 and the external microphone unit 10 have exactly the same
characteristics, the resistor R1 is not necessarily required, but in general, the characteristics are
different between the built-in microphone unit and the external microphone unit Is often
required, and since the resistor R2 is a load for accessories connected to the microphone jack 2,
it is necessary to keep the input impedance high to some extent, so the value of the resistor R2
should be increased. As for the built-in microphone unit 1, it is general to match the sensitivity
necessary for the built-in microphone unit by connecting the resistance R1 in parallel to reduce
the resistance value.
[0015]
However, in the above-described conventional audio recording and reproducing apparatus, when
the external microphone unit 10 is connected, the plus terminal of the built-in microphone unit 1
is disconnected from the point B, but through the resistor R1. Since it is connected to the point A,
the built-in microphone unit 1 itself continues to operate (see FIG. 9).
[0016]
Therefore, the change of the output current generated at the plus terminal according to the
sound inputted to the built-in microphone unit 1 continues, and the current flowing to the
resistors R1 and R3 also fluctuates.
Then, the product of this current change and the resistance R3 appears at point A as a change of
the power supply voltage.
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Most of this voltage change is bypassed to GND through the capacitor C1. However, when an
extremely loud sound is input to the built-in microphone unit 1, the potential at the point A also
greatly fluctuates.
[0017]
Since the potential fluctuation at the point A is transmitted to the point B via the resistor R2, it is
input to the preamplifier 3 (see FIG. 7) through the capacitor C2 and the resistor R2. Therefore,
when using the external microphone unit 10, a part of the sound to be input to the built-in
microphone unit 1 which should be in a non-operating state is mixed in with the main unit, and
distortion is increased and the S / N ratio is also increased. Getting worse.
[0018]
In order to prevent this problem, it is conceivable to make the resistor R3 smaller and make the
capacitor C1 larger. However, in a small portable set, there is a limit to increasing the size of the
capacitor, and the problem is eliminated. It does not reach.
[0019]
In addition, although it is conceivable to stabilize the voltage at point A using a voltage
stabilization circuit or the like, adding a new circuit composed of a plurality of parts is costly and
increases the size of the apparatus. Invite you.
[0020]
Furthermore, there is also a method of detecting the connection of the external microphone unit
by the detection means of the external microphone unit, and cutting off the power supply of the
built-in microphone unit by an electronic switch composed of a transistor etc. And the cost
increases.
[0021]
The present invention has been made in view of such problems, and it is an object of the present
invention to provide an audio recording apparatus which realizes high-quality audio recording
when switching and using a plurality of microphone units with a simple configuration. Do.
[0022]
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5
SUMMARY OF THE INVENTION In order to achieve the above object, a first audio recording
apparatus according to the present invention comprises a first microphone unit which operates
by supplying a direct current, and the audio recording apparatus. Input selection means for
switching the operation from the first microphone unit to the second microphone unit when a
second microphone unit other than the first microphone unit is connected; and a second
microphone unit from the first microphone unit And DC current interrupting means for
interrupting the direct current supplied to the first microphone unit when switching the
operation to the second microphone unit.
[0023]
In order to achieve the above object, the second audio recording apparatus of the present
invention operates by being supplied with a direct current and converts the audio into an electric
signal, and an external microphone unit for the audio recording apparatus. Input selection means
for switching the operation from the built-in microphone unit to the external microphone unit
when the unit is connected, and a direct current supplied to the built-in microphone unit when
the operation is switched from the built-in microphone unit to the external microphone unit And
DC current interrupting means for interrupting
[0024]
In order to achieve the above object, a third audio recording apparatus of the present invention is
the first or second audio recording apparatus, wherein the direct current interruption means is a
capacitor.
[0025]
The first audio recording device operates when the first microphone unit is supplied with a direct
current, and a second microphone unit other than the first microphone unit is connected to the
audio recording device. The operation is switched from the first microphone unit to the second
microphone unit by input selection means.
Further, when the operation is switched from the first microphone unit to the second microphone
unit, the direct current supplied to the first microphone unit is interrupted by the direct current
interrupting means.
[0026]
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6
In the second audio recording apparatus, the built-in microphone unit operates by being supplied
with a direct current, and converts audio into an electrical signal.
Also, when an external microphone unit is connected to the voice recording device, the operation
is switched from the built-in microphone unit to the external microphone unit by the input
selection means.
Furthermore, when the operation is switched from the built-in microphone unit to the external
microphone unit, the direct current supplied to the built-in microphone unit is cut off by the
direct current blocking means.
[0027]
The third audio recording device is the first or second audio recording device, wherein the direct
current cutoff means is a capacitor.
[0028]
BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be
described below with reference to the drawings.
[0029]
FIG. 1 is an electric circuit diagram showing the main configuration of a voice recording
apparatus according to a first embodiment of the present invention.
[0030]
As shown in the figure, the audio recording apparatus includes an internal microphone unit 1 as
a first microphone unit and a microphone jack 2 as input selection means to which an external
microphone unit as a second microphone unit is connected. There is.
The built-in microphone unit 1 is formed of, for example, an electret condenser microphone unit,
the negative (-) terminal is connected to GND, and the positive (+) terminal is connected to the
01-05-2019
7
fixed piece 2B of the microphone jack 2, and the resistor R1. It is connected to the connection
point between the resistor R3 and the capacitor C1 via a series circuit consisting of a capacitor
C3 as a DC current interrupting means.
[0031]
The capacitor C3 functions as a high pass filter for the built-in microphone unit 1, but the
capacitance value for determining the cut-off frequency is set based on the frequency
characteristic of the built-in microphone 1.
Although an electrolytic capacitor is used as the capacitor C3 in the present embodiment, the
present invention is not limited to this, and any capacitance means may be used as long as a DC
component is shut off.
[0032]
The other end of the resistor R3 is connected to the power supply + Vcc, and the other end of the
capacitor C1 is connected to GND. The resistor R3 and the capacitor C1 constitute a ripple filter
for the power supply + Vcc.
[0033]
Here, it is assumed that the point passing the ripple filter from the power supply + Vcc through
the resistor R3 and the capacitor C1 is a point A, and the connection point between the resistor
R2 and the capacitor C2 is a point B.
[0034]
On the other hand, the movable piece 2A of the microphone jack 2 is connected to the
connection point of the capacitor C3, the capacitor C1 and the resistor R3 via the resistor R2 and
to the input end of the preamplifier 3 via the capacitor C2.
Further, the ground piece 2C of the microphone jack 2 is connected to GND.
01-05-2019
8
[0035]
FIG. 2 is an electric circuit diagram showing an equivalent circuit of the built-in microphone unit
1.
[0036]
As shown in FIG. 2, the built-in microphone unit 1 is configured by connecting a capacitor
formed of the vibrating film 13 and the fixed portion 12 between the gate and the source of the
FET (field effect transistor) 11. .
When the vibrating membrane 13 vibrates by voice, the distance between the vibrating
membrane 13 and the fixed portion 12 changes according to the vibration, and the capacitance
of the capacitor also changes accordingly.
Due to this change, the current flowing between the drain and the source of the FET 11 changes,
and the voltage across the load resistors R1 and R2 changes.
In this way, the input voice is converted into an electrical signal and appears at the plus terminal
of the built-in microphone unit 1.
[0037]
FIG. 3 is an explanatory view showing an example of the configuration of an external microphone
unit connected to the voice recording device of the present embodiment.
[0038]
As described above, an external microphone unit can be connected to the microphone jack 2 of
the audio recording device of the present embodiment, and FIG. 3 shows an example of the
external microphone unit.
[0039]
As shown in the figure, the external microphone unit 10 connected to the microphone jack 2 is
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9
usually composed of a microphone unit 10A and a microphone plug unit 10B connected via a
cord extended from the microphone unit 10A.
The negative terminal of the microphone unit 10A is connected to the ground side of the
microphone plug unit 10B, the positive terminal of the microphone unit 10A is connected to the
hot side of the microphone plug unit 10B, and the microphone plug unit 10B is inserted and
connected to the microphone jack 2 It is supposed to be
[0040]
Next, the operation of the voice recording apparatus of the present embodiment having such a
configuration will be described with reference to an equivalent circuit.
[0041]
First, an audio recording operation by the built-in microphone unit 1 will be described with
reference to FIGS.
[0042]
FIG. 4 is an equivalent circuit of the main part of the audio recording apparatus of the present
embodiment, and shows a state in which an external microphone unit is not connected to the
microphone jack 2.
[0043]
As shown in FIG. 4, when the external microphone unit is not connected to the microphone jack
2, direct current is supplied from point A via the resistor R2.
On the other hand, in the AC operating state, approximately, the parallel resistance of the resistor
R1 and the resistor R2 functions as an AC load of the built-in microphone unit 1.
[0044]
That is, in the state where the external microphone unit is not connected to the microphone jack
01-05-2019
10
2, the movable piece 2A of the microphone jack 2 is in contact with the fixed piece 2B (see FIG.
1), and the plus terminal of the built-in microphone unit 1 is B Connected to the point.
In the audio recording and reproducing apparatus shown in FIG. 7, the direct current supply path
from point A to the built-in microphone unit 1 is performed via the parallel combined resistance
of the resistor R1 and the resistor R2 in this embodiment. Since the capacitor C3 is inserted in
series with the resistor R1, the direct current is supplied only through the resistor R2.
[0045]
On the other hand, since the parallel combined resistance value of the resistance R1 and the
resistance R2 becomes the load resistance value of the built-in microphone unit 1 as an
alternating operation, the built-in microphone unit sensitivity almost equal to that of the voice
recording / reproducing device shown in FIG. It will be obtained.
[0046]
At this time, as described above, since the movable piece 2A and the fixed piece 2B of the
microphone jack 2 are connected, the positive terminal of the built-in microphone unit 1 is a
point B which is a connection point of the resistor R2 and the capacitor C2. The same signal as
that which appears at the same time appears on the input and is transmitted to the input of the
preamplifier 3 through the capacitor C2.
[0047]
Next, an audio recording operation when an external microphone unit is connected to the
microphone jack 2 will be described.
[0048]
Returning to FIG. 1, when the external microphone unit 10 (see FIG. 3) is connected to the
microphone jack 2, that is, when the microphone plug portion 10B is inserted into the
microphone jack 2, the movable piece 2A of the microphone jack 2 is Moves away from the fixed
piece 2B and is not in contact with each other.
As a result, the plus terminal of the built-in microphone unit 1 is disconnected from the point B.
01-05-2019
11
[0049]
On the other hand, as the microphone plug portion 10B is inserted into the microphone jack 2,
the hot side of the microphone plug portion 10B is the movable piece 2A of the microphone jack
2, and the ground side of the microphone plug portion 10B is the ground piece 2C of the
microphone jack 2. Will be connected to
[0050]
FIG. 5 is an equivalent circuit of the main part of the voice recording apparatus according to this
embodiment, and shows a state in which an external microphone unit 10 (see FIG. 3) is
connected to the microphone jack 2.
[0051]
As shown in FIG. 5, when the microphone plug unit 10B is inserted into the microphone jack 2,
the plus terminal of the microphone unit 10A is connected to the point B, and the minus terminal
of the microphone unit 10A is connected to GND.
Therefore, current is supplied to the plus terminal of the microphone unit 10A from point A via
the resistor R2, and the sound converted into an electric signal appears at point B in the same
manner as described above for the built-in microphone unit 1. It will be.
[0052]
Further, the movable piece 2A of the microphone jack 2 moves away from the fixed piece 2B and
is not in contact with each other, and the plus terminal of the built-in microphone unit 1 is
disconnected from the point B. The DC supply to the built-in microphone unit 1 is completely cut
off by the inserted capacitor C3, and the built-in microphone unit 1 is completely inactivated.
[0053]
Therefore, when the external microphone unit 10 is connected, no matter what sound is input to
the built-in microphone unit 1, it does not affect the potential at the point A.
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As a result, the audio signal input to the external microphone unit 10 and output to the
preamplifier 3 is not disturbed by the audio input to the built-in microphone unit 1, and an audio
signal with a high S / N ratio without distortion. It is possible to record
[0054]
As described above, according to the present embodiment, the function of the built-in
microphone unit is completely set at the time of connecting the external microphone unit without
changing the AC operation state of the built-in microphone unit by the extremely simple
configuration of adding only one capacitor. Since it can be stopped, the influence of voice input
to the built-in microphone unit can be eliminated in connection with an external microphone
unit, and voice recording with lower distortion and high S / N ratio can be realized.
[0055]
Further, when the external microphone unit is connected, the built-in microphone unit 1 is in a
non-operating state, so that the consumption current can be reduced by the operation current of
the built-in microphone unit 1.
[0056]
Next, a second embodiment of the present invention will be described.
[0057]
FIG. 6 is an electric circuit diagram showing the main configuration of the voice recording
apparatus according to the second embodiment.
In addition, the same code | symbol is provided to the component similar to the said 1st
Embodiment, and detailed description here is abbreviate | omitted.
[0058]
In the second embodiment, the series circuit including the resistor R1 and the capacitor C3 is
inserted between the plus terminal of the built-in microphone unit 1 and the point A in the first
embodiment, while the built-in microphone unit 1 is inserted. It is characterized in that it is
01-05-2019
13
inserted between the plus terminal of and the GND.
The other configuration and operation are the same as those of the first embodiment, and the
detailed description thereof will be omitted.
[0059]
In the second embodiment, as in the first embodiment, when the external microphone unit 10 is
not connected to the microphone jack 2, the direct current is supplied to the built-in microphone
unit 1 via the resistor R2 alone. It will be.
Further, since the point A and GND are in a short circuit state by the capacitor C3, they are used
as the alternating current load of the built-in microphone unit 1 as the parallel combined
resistance of the resistor R1 and the resistor R2 as in the first embodiment. It becomes almost
equal.
[0060]
On the other hand, when the external microphone unit 10 is connected to the microphone jack 2,
the built-in microphone unit 1 is inactivated as in the first embodiment, and the signal from the
built-in microphone unit 1 is the voice of the external microphone unit 10. There is no adverse
effect on the signal.
[0061]
Thus, the second embodiment can achieve the same effect as that of the first embodiment.
[0062]
As described above, according to the first aspect of the present invention, it is possible to provide
an audio recording apparatus which realizes high-quality audio recording when switching and
using a plurality of microphone units.
[0063]
Further, according to the invention of the second aspect, it is possible to provide an audio
recording apparatus which realizes high quality audio recording when using an external
01-05-2019
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microphone unit.
[0064]
Furthermore, according to the voice recording apparatus of the third aspect, it is possible to
provide a voice recording apparatus which realizes high-quality voice recording with a simple
configuration.
[0065]
Brief description of the drawings
[0066]
1 is an electric circuit diagram showing a main part configuration of a voice recording apparatus
according to a first embodiment of the present invention.
[0067]
2 is an electric circuit diagram showing an equivalent circuit of the built-in microphone unit in
the audio recording device of the first embodiment.
[0068]
3 is an explanatory view showing an example of the configuration of an external microphone unit
connected to the voice recording device of the first embodiment.
[0069]
[FIG. 4] It is a principal part equivalent circuit of the said audio recording device in case the
external microphone unit is not connected to the audio recording device of the said 1st
Embodiment.
[0070]
FIG. 5 is a main part equivalent circuit of the audio recording device in the case where an
external microphone unit is connected to the audio recording device of the first embodiment.
[0071]
6 is an electric circuit diagram showing the main configuration of a voice recording apparatus
01-05-2019
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according to a second embodiment of the present invention.
[0072]
7 is an electric circuit diagram showing an example of the audio recording unit in the
conventional audio recording and reproducing apparatus.
[0073]
8 is an equivalent circuit of the main part of the audio recording device when the external
microphone unit is not connected to the audio recording device shown in FIG.
[0074]
[FIG. 9] It is a principal part equivalent circuit of the said audio recording device when an
external microphone unit is connected to the audio recording device shown in the said FIG.
[0075]
Explanation of sign
[0076]
DESCRIPTION OF SYMBOLS 1 ... Built-in microphone unit 2 ... Microphone jack 3 ... Preamplifier
2A ... Movable piece 2B ... Fixed piece 2C ... Earthing piece C1, C2, C3 ... Capacitor R1, R2, R3 ...
Resistance 10 ... External microphone unit 10A ... Microphone part 10B ... Microphone part Plug
part
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