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JP2006313952

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DESCRIPTION JP2006313952
An object of the present invention is to reliably prevent electromagnetic waves from intruding
into an internal circuit from a coupling portion of a microphone unit portion and a microphone
case in a condenser microphone capable of replacing a microphone unit portion, and to prevent
generation of noise caused by electromagnetic waves. . SOLUTION: A microphone case 1, a unit
case 31 which is detachable from the microphone case 1 and incorporates a condenser
microphone unit 30, a circuit board 15 accommodated in the microphone case 1, and the unit
case 31 mounted on the microphone case 1. And an electric path electrically connecting the rear
end of the unit case 31 to the circuit board 15 in the state, the electric path electrically
connecting the rear end of the unit case 31 to the circuit board 15 through the inductor 18 .
[Selected figure] Figure 2
コンデンサーマイクロホン
[0001]
The present invention relates to a condenser microphone capable of attaching and detaching a
microphone unit part to a microphone case, for example, a condenser microphone which can be
arbitrarily replaced with a nondirectional microphone unit part or a unidirectional microphone
unit part, in particular, The present invention relates to a condenser microphone capable of
suppressing an increase in noise due to replacement of a unit.
[0002]
As the condenser microphone, since the impedance of the microphone unit is high, an impedance
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1
converter composed of a field effect transistor (FET) or the like is used.
In addition, an output circuit, a low cut circuit, and the like are incorporated in the microphone in
order to satisfy the performance necessary for the microphone or to perform the necessary
function.
[0003]
On the other hand, there is a condenser microphone in which the microphone unit portion can be
replaced according to the application. For example, there is a condenser microphone in which the
nondirectional microphone unit portion and the unidirectional microphone unit portion can be
selectively replaced and attached. The unit exchange mechanism in a condenser microphone in
which the microphone unit portion is exchangeable is generally designed in a structure in which
a unit case incorporating the microphone unit is screwed to the microphone case. An audio signal
converted from voice to an electrical signal by the microphone unit and output is transmitted to
the microphone case side through the electrical contact, and impedance conversion is performed
by the impedance converter housed in the microphone case to perform low-cut processing , Etc.
are output to the outside.
[0004]
4 and 5 show a conventional example of a condenser microphone in which the microphone unit
portion can be replaced according to the application. In FIGS. 4 and 5, reference numeral 1
denotes a microphone case, and reference numeral 3 denotes a microphone unit portion. The
microphone case 1 has a female screw 19 on the inner peripheral surface of the tip (the left end
in FIG. 4 and FIG. 5), the microphone unit 3 has a male screw 32 at the rear end, and the male
screw 32 is screwed into the female screw 19 Thus, the microphone unit 3 can be coupled to the
microphone case 1.
[0005]
The microphone unit portion 3 has a substantially cylindrical unit case 31, and the condenser
microphone unit 30 is mounted near the tip of the unit case 31. The condenser microphone unit
30 has a generally known unit configuration, and thus the detailed description thereof will be
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2
omitted. The front end of the unit case 31 is covered with a front cover 39 having a plurality of
slit-like sound introduction holes. An inner end plate 33 is fitted and fixed to the rear end side of
the unit case 31 and an outer end plate 34 is fitted and fixed to the outer side of the unit case 31.
In the hole formed at the center of the outer end plate 34, a hooked contact 38 is inserted from
the inside. A rod-shaped terminal 36 is inserted from the outside toward the inside into a hole
formed at the center of the inner end plate 33, and the terminal 36 is fixed to the inner end plate
33 in a form projecting toward the microphone unit 30 There is. A compression spring 37 made
of a conductor is interposed in the central hole of the inner end plate 33 and the outer end plate
34, and the repulsive force of the compression spring 37 pushes the contact 38 toward the
outside of the outer end plate 34. The rear end of the hemispherical contact 38 projects from the
outer end plate 34. An output terminal plate 35 extending rearward from the microphone unit
30 is screwed to the tip of the rod-like terminal 36. Therefore, the audio signal converted by the
microphone unit 30 is transmitted to the output terminal plate 35, the terminal 36, the
compression spring 37, and the contact 38.
[0006]
The microphone case 1 mainly comprises a relatively long cylindrical case 11. An end plate 16 is
fitted and fixed to the inner periphery of the tip end portion of the cylindrical case 11 adjacent to
and behind the female screw 19. A contact 20 is fitted and fixed by penetrating the center of the
end plate 16 in the thickness direction. A circuit board 15 is mounted in the cylindrical case 11
along its length direction. The circuit board 15 incorporates the above-described impedance
conversion circuit mainly composed of the FET, a low cut circuit, an output circuit, and the like.
The contact 20 is connected to the input terminal of the circuit board 15 through a suitable
conductive material. A connector case 12 is fitted to the rear end of the cylindrical case 11 and
fixed by a screw or the like. An insulating connector base 13 is fixed in the connector case 12.
Three conductive pins 14 are embedded in the connector base 13 to form a standardized 3-pin
connector. The output terminal and the ground terminal of the output circuit formed on the
circuit board 15 are electrically connected to the corresponding pins.
[0007]
FIG. 4 shows a state in which the microphone unit portion 3 is coupled to the microphone case 1
by screwing the male screw 32 of the unit case 31 into the female screw 19 of the cylindrical
case 11. In this state, the contact 38 of the microphone unit 3 contacts the tip of the contact 20
on the microphone case 1 side, and the contact 38 is pressed against the contact 20 by the
compression force of the compression spring 37, and the contact 38 and the contact 20 are
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3
electrically linked. Therefore, an audio signal converted and output by the microphone unit 30 is
input to the input terminal of the circuit board 15 through the output terminal plate 35, the
terminal 36, the compression spring 37, the contact 38 and the contact 20. In the circuit board
15, predetermined processing such as impedance conversion, low cut, amplification and the like
is performed, and an output signal is transmitted to the three pins 14 as output terminals. One of
the three pins 14 is a ground pin connected to the ground. A connector plug conforming to the
standard is inserted into the connector case 12, and a signal is input to an external circuit
through the three pins 14 and the microphone cord.
[0008]
According to the conventional condenser microphone described above, since the microphone
case 1 and the microphone unit 3 are electrically connected by screwing the female screw 19
and the male screw 32, the microphone case 1 and the microphone unit 3 become earth. It
functions as a shielding member against external electromagnetic waves. However, since the
coupling portion between the microphone case 1 and the microphone unit portion 3 is a path of
an electromagnetic wave coming from the outside and is also a path of a signal on the ground
side of an audio signal, the structure where the audio signal is easily affected by the
electromagnetic wave It has become. That is, since the screw connection portion of the
microphone case 1 and the microphone unit portion 3 has an impedance to the high frequency
signal, the electromagnetic wave easily enters the internal circuit from the above connection
portion, and the electromagnetic wave embedded in the internal circuit It is because it is detected
by the semiconductor which comprises and produces noise. In particular, when the signal current
flows in the joint portion by the screw, the noise is large. Also, in recent years, when mobile
phones are widely used and frequently used everywhere, the cases where mobile phones are
used near condenser microphones increase and electromagnetic waves emitted from mobile
phones are coupled as described above. There are increasing cases in which the noise from the
condenser microphone is caused by intrusion from the unit.
[0009]
The invention described in the patent document related to the condenser microphone according
to the present invention is a condenser microphone in which a microphone capsule including a
microphone unit can be replaced with a grip portion in which an electric circuit for outputting an
audio signal is built. For example, by providing two pad capacitors in the microphone capsule
and selectively connecting the pad capacitors in parallel to the effective capacitance of the
microphone unit by the changeover switch, sensitivity adjustment at the time of capsule
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replacement can be performed. There is one that can be easily performed (see, for example,
Patent Document 1). Although the invention described in Patent Document 1 is such that the
microphone capsule including the microphone unit can be replaced with respect to the grip
portion, the object is to make it possible to easily perform sensitivity adjustment at the time of
capsule replacement. It is Therefore, as will be described later, in the condenser microphone in
which the microphone unit portion can be replaced, the present invention aims to prevent noise
due to electromagnetic waves entering from the connection portion between the microphone unit
portion and the microphone case. And the purpose is different.
[0010]
As another invention described in another patent document related to the condenser microphone
according to the present invention, in a unidirectional electret condenser microphone, a back
pole holder made of an insulating material for fittingly fixing a back pole plate constituting one
electrode is used. An IC chip is provided inside the back electrode holder, including a lead ring
internally provided in the back electrode holder to electrically connect the back electrode holder
and the printed circuit board, and a capacitor for high frequency noise removal and an inductor
and other circuit elements. The thing fixed and fixed to the printed circuit board accommodated
in the back electrode room to be carried out is known (for example, refer to patent documents 2).
The invention described in Patent Document 2 includes an inductor for removing high frequency
noise, but in the condenser microphone in which the microphone unit portion can be replaced, it
is desired to enter from the coupling portion between the microphone unit portion and the
microphone case. The object of the present invention is different from that of the present
invention, which aims to prevent noise caused by electromagnetic waves.
[0011]
As still another invention described in the patent document, a vibration pickup microphone using
a ceramic bimorph element does not receive digital noise from the cell phone even when the cell
phone is used nearby, and the impedance conversion is performed with the ceramic bimorph
element A vibration pickup microphone is known in which a filter including an inductor and a
capacitor is interposed between an FET as a circuit and the like (see, for example, Patent
Document 3). The invention described in Patent Document 3 prevents digital noise from being
received when a mobile phone is used near the microphone, but in the condenser microphone in
which the microphone unit can be replaced, the microphone unit and The object of the present
invention is different from that of the present invention, which aims to prevent noise due to
electromagnetic waves entering from the coupling portion with the microphone case.
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[0012]
Also, an inductor as an impedance element is interposed in series at a position close to the
microphone of the transmission wave signal output line of the microphone, and the wireless
transmission wave signal induced to the transmission signal output line enters the microphone
by this impedance element. It is also known to be configured to prevent doing so (see, for
example, Patent Document 4). The invention described in Patent Document 4 discloses that the
impedance element connected in series to the transmission wave signal output line of the
microphone has the effect of preventing noise due to electromagnetic waves, but a capacitor that
allows the microphone unit portion to be replaced. The object of the present invention is
different from that of the present invention, which aims to prevent noise due to electromagnetic
waves entering the microphone unit portion and the microphone case in the microphone.
[0013]
JP-A 2004-23705 JP-A 11-30175 JP-A 10-336794 JP-A 9-83463
[0014]
The present invention has been made in view of the problems of the above-described
conventional condenser microphone, and in the condenser microphone in which the microphone
unit portion is attachable to and detachable from the microphone case, the electromagnetic wave
is transmitted from the coupling portion between the microphone unit portion and the
microphone case to the internal circuit. It is an object of the present invention to provide a
condenser microphone capable of preventing intrusion of the magnetic flux and preventing
generation of noise caused by electromagnetic waves.
[0015]
According to the present invention, the rear end of the unit case is attached to the microphone
case, the unit case detachable from the microphone case and incorporating the condenser
microphone unit, the circuit board housed in the microphone case, and the unit case attached to
the microphone case. An electric path electrically connected to the circuit board is provided, and
the electric path is most mainly characterized in that the electric path electrically connects the
rear end of the unit case to the circuit board via an inductor.
[0016]
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The unit case can be attached to and detached from the microphone case. If multiple types of
unit cases or microphone units with different specifications of the built-in condenser microphone
unit are prepared, any specifications can be selected according to the usage conditions of the
microphone, etc. The unit case or the microphone unit portion can be selected and attached to
the microphone case and used as a microphone of a specification adapted to the user's intention.
With the unit case mounted on the microphone case, the rear end of the unit case is electrically
connected to the circuit board in the microphone case via the inductor, and the unit case
together with the microphone case serves as a ground side electrical path for audio current and
high frequency current Act as.
In the microphone case, since the microphone case which is the ground side electric path of the
high frequency current and the ground side electric path of the circuit board which is the ground
side electric path of the audio current are separated, the electric path on the circuit board is
isolated from the high frequency current, It is possible to obtain a clear voice signal with little
noise without noise mixed in the voice circuit due to high frequency current.
[0017]
Hereinafter, embodiments of a condenser microphone according to the present invention will be
described with reference to the drawings.
The same reference numerals as in the prior art shown in FIGS. 4 and 5 denote the same parts.
Further, the illustrated embodiment is a condenser microphone in which the microphone unit
portion can be arbitrarily replaced with, for example, a nondirectional microphone unit portion
or a unidirectional microphone unit portion, or microphone unit portions of other specifications.
Above, only one type of microphone unit is shown.
[0018]
In FIGS. 1 and 2, reference numeral 1 denotes a microphone case, and reference numeral 3
denotes a microphone unit portion. The microphone case 1 has an internal thread 19 on the
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inner peripheral surface of the front end (left end in FIGS. 1 and 2), and the microphone unit 3
has an external thread 32 on the rear end. The microphone unit portion 3 can be coupled to the
microphone case 1 by relatively rotating the microphone case 1 and the microphone unit portion
3 around their central axes and screwing the female screw 19 and the male screw 32. Further, by
unscrewing the female screw 19 and the male screw 32, the connection between the microphone
case 1 and the microphone unit 3 can be released.
[0019]
The microphone unit portion 3 has a substantially cylindrical unit case 31, and the condenser
microphone unit 30 is mounted at a position near the tip in the unit case 31. Condenser
microphone unit 30 may be of a general configuration known in the art, and may have a slight
gap with the diaphragm on which the outer peripheral edge on one side is held by a holding ring
and the interposition of a spacer At the same time, it is composed of a fixed pole opposite to the
above-mentioned holding ring and other appropriate parts. As shown in FIGS. 3A and 3B, a front
cover 39 having a plurality of slit-like sound introduction holes 391 is placed on the tip of the
unit case 31. On the front side of the condenser microphone unit 30, there is a front acoustic
terminal which is an entrance for voice. In the case of a unidirectional microphone unit, a rear
acoustic terminal is provided.
[0020]
An inner end plate 33 is fitted and fixed to the rear end side of the unit case 31, and an outer end
plate 34 is fitted and fixed adjacent to the outer side of the unit case 31. In the hole formed at
the center of the outer end plate 34, a hooked contact 38 is inserted from the inside. A rodshaped terminal 36 is inserted from the outside toward the inside into a hole formed at the
center of the inner end plate 33, and the terminal 36 is fixed to the inner end plate 33 in a form
projecting toward the microphone unit 30 There is. A compression spring 37 made of a
conductor is interposed in the central hole of the inner end plate 33 and the outer end plate 34,
and the repulsive force of the compression spring 37 pushes the contact 38 toward the outside
of the outer end plate 34. The rear end of the hemispherical contact 38 projects outwardly from
the outer end plate 34. An output terminal plate 35 extending rearward from the microphone
unit 30 is screwed to the tip of the rod-like terminal 36. Therefore, the audio signal converted by
the microphone unit 30 is transmitted to the output terminal plate 35, the terminal 36, the
compression spring 37, and the contact 38.
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[0021]
The microphone case 1 mainly comprises a relatively long cylindrical case 11 which serves as a
grip of the microphone. An end plate 16 is fitted and fixed to the inner periphery of the tip end
portion of the cylindrical case 11 adjacent to and behind the female screw 19. A contact 20 is
fitted and fixed by penetrating the center of the end plate 16 in the thickness direction. A circuit
board 15 is disposed and attached in the cylindrical case 11 along the length direction. The
circuit board 15 incorporates the above-described impedance conversion circuit mainly
composed of the FET, a low cut circuit, an output circuit, and the like. The contact point 20 is
connected to an input terminal of the circuit board 15 or a solder land which functions as an
input terminal via a suitable conductive material. A connector case 12 is fitted to the rear end of
the cylindrical case 11 and fixed by a screw or the like. An insulating connector base 13 is fixed
in the connector case 12. Three pins 14 made of a conductive material are embedded in the
connector base 13 to form a standardized 3-pin connector. The output terminal and the ground
terminal of the output circuit formed on the circuit board 15 are electrically connected to the
corresponding pins.
[0022]
FIG. 1 shows a state in which the microphone unit portion 3 is coupled to the microphone case 1
by screwing the male screw 32 of the unit case 31 into the female screw 19 of the cylindrical
case 11. The contact 20 disposed in the cylindrical case 11 forming the main body of the
microphone case 1 and the contact 38 disposed in the unit case 31 are disposed at relative
rotation centers when the microphone unit 3 is attached to and detached from the microphone
case 1. ing. Further, when the unit case 31 is mounted on the cylindrical case 11, the contacts 20
and 38 of the cylindrical case 11 and the unit case 31 are configured to be in contact with each
other. The contacts 20 and 38 are contacts for transmitting an audio signal. In the state where
the microphone unit 3 is coupled to the microphone case 1 as described above, the contact 38 of
the microphone unit 3 contacts the tip of the contact 20 on the microphone case 1 side, and the
contact 38 is a contact due to the compression force of the compression spring 37 When pressed
by 20, the contact 38 and the contact 20 are electrically connected. Therefore, the audio signal
converted and output by the microphone unit 30 is input to the audio signal input terminal of the
circuit board 15 through the output terminal plate 35, the terminal 36, the compression spring
37, the contact 38 and the contact 20. In the circuit board 15, predetermined processing such as
impedance conversion, low cut, amplification and the like is performed, and an output signal is
transmitted to the three pins 14 as output terminals. One of the three pins 14 is a ground pin
connected to the ground. A connector plug conforming to the standard is inserted into the
connector case 12, and a signal is input to an external circuit through the three pins 14 and the
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microphone cord.
[0023]
The description so far is almost the same as the configuration of the conventional condenser
microphone shown in FIGS. 4 and 5. The configuration described below is a characteristic
configuration of the present invention. In FIG. 1 and FIG. 2, the contact 17 is attached to the end
outer surface side, that is, the microphone unit portion 3 side, of the end plate 16 made of an
insulating material installed near the tip of the cylindrical case 11. The contact 17 is formed in a
ring shape, and the inner peripheral edge portion of the contact 17 is drawn in a cylindrical
shape toward the inner side of the microphone case 1, and the cylindrical inner peripheral edge
portion is stepped in the end plate 16. It is fitted in the cylindrical part formed in. The outer
peripheral edge portion of the contact 17 is drawn in a cylindrical shape toward the outside of
the microphone case 1 which is opposite to the inner peripheral edge portion. The front end of
the cylindrical outer peripheral edge portion of the contact 17 faces the rear end surface of the
unit case 31 coupled to the microphone case 1, and the microphone case 1 and the microphone
unit portion are screwed by the above-mentioned female screw 19 and male screw 32. In a state
in which it is coupled with 3, the front end of the cylindrical outer peripheral edge portion of the
contact 17 is in pressure contact with the rear end surface of the unit case 31. The contact 17
has conductivity and elasticity, and as described above, the contact 17 is bent when the front end
of the cylindrical outer peripheral edge of the contact 17 is in pressure contact with the rear end
face of the unit case 31. The contact 17 is pressed against the unit case 31 by this biasing force,
and the contact 17 is electrically integrally coupled to the unit case 31. The contacts 17 need to
be configured to be able to flex as described above. Therefore, only the cylindrical portion
formed on the inner peripheral side is fixed to the end plate 16, and the other portion is in a state
of floating from the end plate 16. In addition, in order to make the contact 17 easy to bend, a
plurality of radial slits may be formed in a portion other than the cylindrical portion on the inner
peripheral side.
[0024]
One end of an inductor 18 is connected to the contact 17. The other end of the inductor 18 is
connected to an electrode or a ground pattern formed on the circuit board 15 by an appropriate
electrical connection means such as soldering. One end of the inductor 18 passes through the
end plate 16 and is connected to the contact 17 by appropriate electrical connection means such
as soldering. The ground pattern of the circuit board 15 is a ground pattern of the audio signal
circuit, and this ground pattern is connected to the unit case 31 of the condenser microphone
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unit 3 via an electric path consisting of an inductor 18 and a contact 17. In other words, the
contact 17 and the inductor 18 constitute an electric path which electrically connects the rear
end of the unit case 31 to the circuit board 15 in a state where the unit case 31 is mounted on
the microphone case 1.
[0025]
On the other hand, a high frequency current caused by an electromagnetic wave entering from
the outside flows to the cylindrical case 11 and the unit case 31 through the joint portion of the
cylindrical case 11 and the unit case 31 which are main components of the microphone case 1.
The ground side current of the high frequency current and the audio signal flows in the unit case
31. However, in the microphone case 1 and in the connecting portion between the cylindrical
case 11 and the unit case 31 where the audio signal is easily influenced by the high frequency
current. Since the electric path of the high-frequency current and the electric path on the ground
side of the audio signal are separated by the inductor 18, noise caused by the high-frequency
current is not mixed into the audio signal, and a high-quality condenser microphone can be
obtained. .
[0026]
The present invention can be applied to a condenser microphone in which the microphone unit
portion is attachable to and detachable from the microphone case. In particular, the present
invention is effective in a condenser microphone in which microphone units having different
specifications can be selected and attached to the microphone case. In that case, the unit case
allows any one of a plurality of unit cases classified for each condenser microphone unit having
different specifications to be selected and attached to the microphone case. Therefore, even if the
condenser microphone units have different specifications, the specifications of the coupling
portion with the microphone case of the unit case are common.
[0027]
It is a longitudinal cross-sectional view which shows the Example of the condenser microphone
concerning this invention. It is a longitudinal cross-sectional view which shows the said Example
in the state which isolate | separated the microphone unit part from the microphone case. The
microphone unit part in the said Example is shown, (a) is a front view, (b) is a side view. It is a
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longitudinal cross-sectional view which shows the example of the conventional condenser
microphone. It is a longitudinal cross-sectional view which shows the said prior art example in
the state which isolate | separated the microphone unit part from the microphone case.
Explanation of sign
[0028]
DESCRIPTION OF SYMBOLS 1 Microphone case 3 Microphone unit part 11 Cylindrical case 15
Circuit board 17 Contactor 18 Inductor 19 Female screw 20 Contacts 30 Condenser microphone
unit 31 Unit case 32 Male screw 38 Contacts
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