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DESCRIPTION JP2016082415

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DESCRIPTION JP2016082415
Abstract: PROBLEM TO BE SOLVED: To prevent disturbance of a frequency response caused by a
resonance phenomenon due to an acoustic capacity formed in a back space of a diaphragm and a
magnetic gap. A magnetic circuit 1 includes a diaphragm 7, a voice coil 8 fixed to the diaphragm,
and a magnetic gap G in which the voice coil is disposed, and generates a magnetic field in the
magnetic gap; It is attached to the circuit, disposed in the back space of the diaphragm 7, and
formed along the space between the volume reducing member 21 and the magnetic circuit 1
with the volume reducing member 21 for reducing the volume of the air chamber in the back
space. A communication passage 21b for communicating the rear space with the back air
chamber 12 and an acoustic resistance 22 attached to the magnetic circuit 1 and interposed
between the communication passage 21b and the back air chamber 12 are provided. [Selected
figure] Figure 1
ダイナミックマイクロホンユニットおよびダイナミックマイクロホン
[0001]
The present invention relates to a dynamic microphone unit, and more particularly, to a dynamic
microphone unit that prevents generation of unevenness in frequency response due to resonance
between an air chamber formed on the back of a diaphragm and an acoustic mass formed on a
magnetic gap. The present invention relates to a dynamic microphone using
[0002]
The nondirectional component of the dynamic microphone is resistance control.
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1
For this purpose, an acoustic resistance is disposed on the back side of the diaphragm, and the
acoustic resistance is used to connect the back of the diaphragm to the back air chamber. The
acoustic resistance realizes resistance control.
[0003]
FIG. 6 is a sectional view showing an example of a conventional dynamic microphone unit.
Reference numeral 1 denotes a magnetic circuit. The magnetic circuit 1 is provided with a diskshaped magnet 2 at the center, and a disk-shaped pole piece 3 is disposed in contact with one of
the magnetic poles of the magnet 2. Further, a tail yoke 4 is provided in contact with the other
pole of the magnet 2, and the peripheral edge portion of the tail yoke 4 is erected in an annular
shape, and the inner peripheral surface of the erected portion and the peripheral edge of the pole
piece 3 An annular magnetic gap G is formed between the surface and the surface. Further,
through holes 5 are formed concentrically in the pole piece 3, the magnet 2 and the tail yoke 4
so as to penetrate the central portions of these.
[0004]
The magnetic circuit 1 including the magnet 2, the pole piece 3 and the tail yoke 4 is attached to
a unit case 6 supporting the tail yoke 4, and the diaphragm 7 is attached to the front of the
opening edge of the unit case 6. ing. The diaphragm 7 is configured by a center dome 7a whose
front surface protrudes in a hemispherical shape, and a sub dome 7b which is annularly formed
along the periphery of the center dome 7a and whose front surface protrudes in an arc shape.
The voice coil 8 is fixed to the diaphragm 7 by using, for example, an adhesive at the boundary
between the center dome 7a and the sub dome 7b on the back side of the diaphragm 7.
[0005]
The peripheral edge portion of the sub dome 7b is attached to the opening edge of the unit case
6, and in this state, the voice coil 8 is configured to be located in the magnetic gap G. With this
configuration, when sound waves are received, the center dome 7a and the voice coil 8 can be
integrally vibrated in the front-rear direction with the outer peripheral edge of the sub dome 7b
as a fulcrum by the sound pressure. Thereby, the voice coil 8 can cross the magnetic field
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generated in the magnetic gap G to provide an audio signal based on the vibration of the
diaphragm 7.
[0006]
Further, an equalizer 9 also serving as a protective member for the diaphragm 7 is attached to
the outer peripheral surface of the front end portion of the unit case 6 so as to cover the unit
case 6 and the diaphragm 7. The surface of the central portion of the equalizer 9 facing the
center dome 7a is formed in a concave spherical shape so as to maintain a fixed gap with the
center dome 7a. Further, in the equalizer 9, an opening 9a is formed at a central portion and a
plurality of openings 9b are formed along the periphery thereof in order to guide a sound wave
from the outside to the diaphragm 7.
[0007]
The back side of the unit case 5 is opened in a cylindrical shape, and is attached by fitting the
container-like lid 11 to the cylindrical opening so as to close the back of the unit case 6 There is.
As a result, a relatively large volume of back air chamber 12 is formed in the container-like lid
11. The back air chamber 12 is formed on the back side of the magnetic circuit 1 (opposite to the
diaphragm 7).
[0008]
On the other hand, a volume reducing member 13 formed in a lens shape is disposed to face the
back surface of the center dome 7a. The volume reducing member 13 is attached to the pole
piece 3 constituting the magnetic circuit 1 by, for example, an adhesive, and the front surface
thereof is spherically protruded along the back surface of the center dome 7a. Then, in the
central portion of the volume reduction member 13, a through hole (a through hole of the
magnetic circuit is formed concentrically with the through hole 5 formed in the magnet 2, the
pole piece 3, and the tail yoke 4 constituting the magnetic circuit 1 described above The same
reference numeral 5 is shown. ) Is formed. Thus, the back surface of the diaphragm 7 is in
communication with the back air chamber 12 formed in the container-like lid 11 through the
through hole 5.
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[0009]
An acoustic resistor 14 is attached to the through hole 5 of the volume reducing member 13. The
acoustic resistor 14 shown in this example is in the form of a sheet. Therefore, a flat recess 13a
is formed in the center of the volume reducing member 13, and the sheet-like acoustic resistance
is formed by using the recess 13a. The body 14 is attached by an adhesive.
[0010]
The volume reducing member 13 is used to prevent the formation of a small volume air chamber
between the back surface of the diaphragm 7, in particular the back surface of the center dome
7a, and the pole piece 3 of the magnetic circuit 1. Be That is, when a small capacity air chamber
is formed between the back surface of the diaphragm 7 and the pole piece 3 constituting the
magnetic circuit 1, this air chamber works as an acoustic capacity (C component). On the other
hand, as described above, since the voice coil 8 is disposed in the magnetic gap G, an acoustic
resistance and an acoustic mass are formed on the inside and the outside of the voice coil 8,
respectively.
[0011]
For this reason, resonance occurs due to the acoustic capacity (C component) of the air chamber
and the acoustic mass (L component) formed in the magnetic gap G, causing a problem of
generating unevenness in the frequency response of the microphone unit. . The resonance
frequency at this time is preferably at or above the upper limit of the main sound collection band
of the microphone unit. Therefore, the lens-shaped volume reduction member 13 described
above is disposed on the front surface of the pole piece 3 to It is desirable to reduce the
component) and set the resonance frequency to be outside the sound collection band.
[0012]
As described above, the lens-shaped volume reducing member 13 is disposed on the front
surface of the magnetic circuit 1, and the back surface of the diaphragm 7 is communicated with
the back air chamber 12 through the through hole 5 formed in the central portion thereof. The
dynamic microphone unit is disclosed in the following Patent Documents 1 to 3 and the like.
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[0013]
JP-A-2013-55396 JP-A-2013-55397 JP-A-2013-141189
[0014]
By the way, in the dynamic microphone unit shown in FIG. 6, the lens-shaped volume reducing
member 13 is disposed on the front surface of the pole piece 3 to reduce the acoustic capacity (C
component) of the air chamber formed on the back surface of the center dome 7a. Although the
configuration is adopted, a recessed portion 13 a for attaching the acoustic resistor 14 is formed
at the central portion of the volume reducing member 13.
For this purpose, the recess 13a still acts as an acoustic capacitance, and this acoustic
capacitance interacts with the acoustic mass (L component) formed in the magnetic gap G to
resonate in the sound collection band of the microphone unit The problem is left.
[0015]
This invention is made based on the above-mentioned technical point, and devises in the
communication passage to the back air room formed in the above-mentioned lens-like volume
reduction member and an acoustic resistor, and in particular, a center dome. It is an object of the
present invention to provide a dynamic microphone unit capable of preventing the disturbance of
the frequency response due to the above-mentioned resonance, and a dynamic microphone using
the same, by configuring the acoustic capacity of the air chamber formed on the back of It is
[0016]
The first preferred embodiment of a dynamic microphone unit according to the present
invention, which has been made to achieve the above-mentioned problems, comprises a
diaphragm, a voice coil fixed to the diaphragm, and a magnetic gap in which the voice coil is
disposed. A magnetic circuit for generating a magnetic field in the magnetic gap; a volume
reducing member attached to the magnetic circuit and disposed in the back space of the
diaphragm to reduce the volume of the air chamber in the back space; A sound path is formed
along the space between the storage member and the magnetic circuit, and connects the back
space to the back air chamber, and is attached to the magnetic circuit, and is interposed between
the communication path and the back air chamber. And a resistor.
[0017]
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Further, a second preferred embodiment of a dynamic microphone unit according to the present
invention, which was made to achieve the above-mentioned problems, is a diaphragm, a voice coil
fixed to the diaphragm, and a magnet in which the voice coil is disposed. A magnetic circuit
including a gap and generating a magnetic field in the magnetic gap, and a volume reducing
member attached to the magnetic circuit and disposed in the back space of the diaphragm to
reduce the volume of the air chamber in the back space; And an acoustic resistance formed of a
thin air layer formed along the space between the volume-reducing member and the magnetic
circuit and communicating the back space with the back air chamber.
[0018]
In this case, in the first embodiment, the through hole formed in the magnetic circuit is
interposed between the communication passage and the back air chamber, and the through hole
is formed in a cylindrical shape. A configuration in which acoustic resistance is arranged is
adopted.
Furthermore, in this case, a configuration in which the volume reducing member is supported on
the magnetic circuit by the cylindrically formed acoustic resistance can be suitably adopted.
[0019]
In the first and second embodiments described above, the diaphragm is composed of a center
dome whose front face protrudes in a hemispherical shape, and an annular sub dome formed
along the periphery of the center dome, The surface of the volume reducing member facing the
center dome has a spherical configuration along the back of the center dome.
[0020]
In addition, the sub dome is annularly formed along the periphery of the center dome, and the
front surface thereof is formed so as to project in an arc shape, and is formed annularly along the
back surface of the sub dome in the back space of the sub dome. It is desirable that a second
volume-reducing member which is formed and whose front face protrudes in an arc shape is
further disposed.
[0021]
And the dynamic microphone unit of the above-mentioned composition can be provided as a
dynamic microphone in the state where it was built in a microphone case.
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[0022]
According to the dynamic microphone unit configured as described above and the dynamic
microphone using the same, the volume reducing member for reducing the volume of the back
space of the diaphragm is attached to the magnetic circuit and formed along the space between
the volume reducing member and the magnetic circuit A configuration is employed in which the
back space of the diaphragm communicates with the back air chamber via the communication
passage.
In the first embodiment, an acoustic resistance is attached to the magnetic circuit immediately
after the communication path, and the magnetic circuit communicates with the back space via
the acoustic resistance.
In the second embodiment, the communication passage formed along the space between the
volume-reducing member and the magnetic circuit is configured as an acoustic resistance made
of a thin air layer.
[0023]
Therefore, according to the first and second embodiments described above, vibration is made in
comparison with the conventional configuration shown in FIG. 6 in which a recessed portion is
formed in the central portion of the lens-shaped volume reducing member for disposing the
acoustic resistance. The volume of the back space of the plate can be reliably reduced.
As a result, the acoustic capacity of the air chamber formed on the back surface of the diaphragm
can be made smaller, and the dynamic microphone unit capable of effectively preventing the
disturbance of the frequency response due to the above-mentioned resonance Dynamic
microphones can be provided.
[0024]
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FIG. 1 is a cross-sectional view showing a first embodiment of a dynamic microphone unit
according to the present invention.
It is sectional drawing of the volume reduction member formed in the lens shape.
It is a bottom view of a volume reduction member similarly.
FIG. 7 is a cross-sectional view showing a second embodiment of a dynamic microphone unit
according to the present invention. It is a sectional view showing the 3rd example similarly. It is
sectional drawing which similarly showed 4th Example. It is sectional drawing which showed an
example of the conventional dynamic microphone unit.
[0025]
The dynamic microphone unit according to the present invention will be described based on
FIGS. 1 to 5. In each embodiment shown below, the part which fulfills the same function as each
part shown in Drawing 6 already explained is shown with the same numerals. Therefore, the
detailed description is suitably omitted.
[0026]
In the first configuration of the dynamic microphone unit according to the present invention
shown in FIG. 1, the volume reducing member 21 shown in FIGS. 2A and 2B is used. As described
above, this volume reducing member 21 is attached to the front surface of the pole piece 3
constituting the magnetic circuit 1 and disposed in the back space of the diaphragm 7 to reduce
the volume of the air chamber in the back space. Play. That is, as shown in FIG. 1, the front
surface of the volume reducing member 21 faces the back surface of the center dome 7a, and is
formed in a spherical shape along the back surface of the center dome 7a. Thus, a constant gap
of about 0.5 mm is formed between the front surface of the volume reducing member 21 and the
back surface of the center dome 7a.
[0027]
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As shown in FIGS. 2A and 2B, the volume reducing member 21 is formed with a bottomed hole
21a at the center of its back surface, and a plurality of cut-out portions fanned with the bottomed
hole 21a at the center. 21b is applied. That is, as shown in FIG. 2B, the fan-like cut-out portion
21b provided on the back surface of the volume reducing member 21 has a fan angle θ set at
about 60 degrees around the bottomed hole 21a. Three cutouts 21b are formed at intervals.
Therefore, the remaining surface 21 c other than the fan-shaped cut-out portion 21 b shown in
FIG. 2B functions as a bonding surface to the pole piece 3 constituting the magnetic circuit 1.
[0028]
Then, as shown in FIG. 1, a cylindrical acoustic resistance 22 is inserted into the through hole 5
formed in the magnetic circuit 1. The tip of the cylindrical acoustic resistance 22 is inserted into
the bottomed hole 21 a of the volume reducing member 21 so that the volume reducing member
21 is positioned with respect to the magnetic circuit 1 and the front surface of the pole piece 3 is
It is attached. In this case, it is desirable to bond the volume reducing member 21 to the pole
piece 3 in a state where an adhesive is applied in advance to the joint surface 21 c of the volume
reducing member 21 to the pole piece.
[0029]
The fan-shaped cut-out portion 21 b thus applied to the volume reducing member 21 functions
as a communication passage formed along the space between the volume reducing member 21
and the magnetic circuit 1 as shown in FIG. 1. That is, the back space of the diaphragm 7 is in
communication with the above-described back air chamber 12 through the communication path
(the cut-out portion 21b). Then, the acoustic resistance 22 formed in a cylindrical shape is
attached to the magnetic circuit 1 and functions as an acoustic resistance interposed between the
communication path (the cutout 21b) and the back air chamber 12 described above. . The
clearance by the communication passage (the cut-out portion 21b) in this case is preferably set
to about 0.4 mm. Further, the fan angle θ of the cut-off portion 21b for forming the
communication passage can be appropriately set, for example, in the range of 3 to 60 degrees, as
necessary.
[0030]
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A so-called sintered plastic material can be suitably used for the cylindrical acoustic resistance
22 described above. This can be obtained, for example, in the form of a porous body by placing
resin powder in a cylindrical mold and applying pressure and heat. And various acoustic
resistance values can be selected depending on the particle size of the resin powder and the
degree of pressurization. In addition, since the sintered plastic material can have a certain degree
of mechanical strength, it can be used as a means for positioning the volume reducing member
21 with respect to the magnetic circuit 1 as described above.
[0031]
According to the dynamic microphone unit shown in FIG. 1, the communication passage for
communicating the back space of the diaphragm 7 with the back air chamber 12 is formed along
the space between the volume reducing member 21 and the magnetic circuit 1, so that FIG.
Compared to the conventional dynamic microphone unit, the acoustic capacity of the air chamber
formed on the back surface of the diaphragm 7 can be configured smaller. Therefore, it is
possible to provide a dynamic microphone unit capable of effectively preventing the disturbance
of the frequency response due to the resonance of the air chamber formed on the back surface of
the diaphragm 7 and the acoustic mass formed on the magnetic gap G.
[0032]
The example shown in FIG. 1 shows a nondirectional dynamic microphone unit in which the back
air chamber 12 is sealed by a container-like lid 11. The back air chamber 12 is formed on the
back side of the magnetic circuit 1 (opposite to the diaphragm 7). In this case, as shown by, for
example, imaginary lines in FIG. 1, a plurality of rear acoustic terminal holes 31 are formed in the
circumferential direction at the opening edge of unit case 6, and sheet-like acoustic resistance 32
is formed in each of rear acoustic terminal holes 31. Can be added to the back of the diaphragm
7. As a result, it is possible to provide a unidirectional dynamic microphone unit having
substantially the same effects as the example shown in FIG.
[0033]
FIG. 3 shows a second configuration of the dynamic microphone unit according to the present
invention. In the example shown in FIG. 3, in addition to the configuration of the dynamic
microphone unit shown in FIG. 1, a volume reducing member is provided also in the back space
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of the sub dome 7b. That is, the sub dome 7b is annularly formed along the periphery of the
center dome 7a, and the front surface thereof is formed so as to protrude in an arc shape.
[0034]
Therefore, in the back space of the sub dome 7b, there is disposed a second volume reducing
member 6a which is annularly formed along the back surface of the sub dome and whose front
surface protrudes in an arc shape. The second volume reducing member 6 a is integrally formed
along the opening edge of the unit case 6 on the front side of the unit case 6. Thus, a constant
gap of about 0.5 mm is formed between the front surface of the second volume reducing member
6a and the back surface of the sub dome 7b, and the acoustic capacity of the air chamber formed
on the back surface of the sub dome 7b is It can be set smaller.
[0035]
Therefore, according to the configuration shown in FIG. 3, according to the operation and effect
described above by the dynamic microphone unit shown in FIG. 1, the frequency due to the
resonance between the air chamber formed on the back surface of subdome 7b and the acoustic
mass formed in magnetic gap G It is possible to provide a dynamic microphone unit to which an
effect of preventing a response disturbance is also added.
[0036]
FIG. 4 shows a third configuration of the dynamic microphone unit according to the present
invention.
In this third example, while the example shown in FIG. 1 uses the acoustic resistance 22 formed
in a cylindrical shape, the sheet-like acoustic resistance 23 is used, and the other configuration is
shown in FIG. The configuration is the same as that of the dynamic microphone unit. That is, as
shown in FIG. 4, the sheet-like acoustic resistance 23 is attached using, for example, an adhesive
so as to close the through hole 5 formed in the central portion of the tail yoke constituting the
magnetic circuit 1. There is.
[0037]
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With this configuration, the sheet-like acoustic resistance 23 is formed by the communication
path (the cut-out portion 21b of the volume reducing member 21) formed along the space
between the volume reducing member 21 and the magnetic circuit 1, and the back air chamber
Intervened between 12 and. Therefore, also in the configuration of the dynamic microphone unit
shown in FIG. 4, the same function and effect as those of the dynamic microphone unit shown in
FIG. 1 can be obtained.
[0038]
FIG. 5 shows a fourth configuration of the dynamic microphone unit according to the present
invention. In the fourth example, acoustic resistance composed of a thin air layer is used in place
of the cylindrical acoustic resistance 22 and the sheet-like acoustic resistance 23 described
above. That is, in the configuration of the volume reducing member 21 used in this example, the
gap between the volume reducing member 21 and the magnetic circuit 1 generated by the cutout portion 21b shown in FIGS. 2A and 2B is set extremely small. An acoustic resistance is
formed between the circuit 1 and the thin air layer.
[0039]
In FIG. 5, the acoustic resistance by the thin air layer is indicated by reference numeral 21d, and
in order to form the acoustic resistance 21d by the thin air layer, the space between the volume
reducing member 21 and the pole piece 3 constituting the magnetic circuit 1 is shown. The gap
of is set to about 50 .mu.m. According to the configuration of the dynamic microphone unit
shown in FIG. 5, the back space of diaphragm 7 has a back portion through acoustic resistance
21d by a thin air layer formed along between volume reducing member 21 and magnetic circuit
1. It communicates with the air chamber 12. As a result, it is possible to provide a dynamic
microphone unit having the same operation and effect as the example shown in FIG. 1 described
above.
[0040]
In the dynamic microphone unit shown in FIGS. 4 and 5, the second volume reducing member 6a
similar to the example shown in FIG. 3 can be formed in the back space of the sub dome 7b.
Thereby, the same effect as that of the example described based on FIG. 3 can be obtained.
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[0041]
The dynamic microphone unit described above can be assembled into a microphone case, and
further, a connector for outputting an output signal of the microphone unit to the outside can be
assembled to the microphone case, thereby constituting a dynamic microphone to be put to
practical use.
[0042]
Reference Signs List 1 magnetic circuit 2 magnet 3 pole piece 4 tail yoke 5 through hole 6 unit
case 6 a second volume reducing member 7 diaphragm 7 a center dome 7 b sub dome 8 voice
coil 9 equalizer 11 container-like lid 12 back air chamber 21 volume reducing member 21 a
Bottomed hole 21b Cutaway portion (communication passage) 21c Bonding surface 21d Thin air
layer (acoustic resistance) 22 Acoustic resistance (cylindrical shape) 23 Acoustic resistance
(sheet shape) G Magnetic gap
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