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DESCRIPTION JP2015213280

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DESCRIPTION JP2015213280
An object of the present invention is to easily adjust the acoustic resistance in a rear acoustic
terminal, reduce variation in characteristics, and improve yield in a unidirectional directivity
condenser microphone unit having acoustic terminals at the front and back. SOLUTION: A
damper member 10 provided on the rear side of a fixed pole and forming an acoustic resistance
on the rear acoustic terminal side is provided, and the damper member 10 has a cylindrical
member 11 whose front end is in contact with the fixed pole side; And an acoustic resistance
material 12 which is housed therein and which is made by compression molding of a plastically
deformable fiber. [Selected figure] Figure 2
コンデンサマイクロホンユニット
[0001]
The present invention relates to a condenser microphone unit in which a diaphragm vibrated by
a sound wave is disposed opposite to a fixed pole, and more particularly to a unidirectional
microphone array in which acoustic terminals are provided at front and back.
[0002]
The unidirectional condenser microphone unit has an acoustic terminal before and after the
diaphragm and the fixed pole disposed opposite to each other.
Sound waves to be collected are collected from the diaphragm and an acoustic terminal (front
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acoustic terminal) on the front side of the fixed pole. At this time, unwanted sound waves, for
example, ambient noise, are transmitted to the diaphragm via the front acoustic terminal and the
rear acoustic terminal and canceled each other. The sound wave applied from the rear acoustic
terminal is divided by the impedance of the acoustic resistance (damper) and the acoustic
capacity of the air chamber at the rear of the fixed pole and is transmitted to the rear of the
diaphragm. In such a unidirectional condenser microphone unit, various directivity
characteristics such as cardioid, hypercardioid, and subcardioid are realized by changing the
acoustic resistance provided on the rear acoustic terminal side. .
[0003]
FIG. 5 is a cross-sectional view of a conventional unidirectional condenser microphone unit. The
condenser microphone unit 50 illustrated includes a cylindrical head case 51 whose rear end
side is open. A plurality of openings 51a are formed on the front side of the head case 51, and a
plurality of openings 51b are formed on the rear side. Further, on the front side in the head case
51, a diaphragm 53 stretched on the support ring 52 is disposed to face the fixed pole 55. An
annular spacer 54 is provided between the diaphragm 53 and the fixed electrode 55. Due to this,
the diaphragm 53 and the fixed electrode 55 are installed so as not to be in contact with each
other.
[0004]
In addition, a disk-shaped insulating seat 56 is provided on the back side of the fixed electrode
55. The peripheral edge of the insulating seat 56 stands on the front side of the head case 51,
and the peripheral edge of the fixed pole 55 is pressed toward the front side of the head case 51.
Further, at the center of the insulating seat 56, a cylindrical pipe portion 56a erected on the rear
side is provided. The outer peripheral surface of the pipe portion 56a is threaded in the
circumferential direction. Further, around the pipe portion 56a in the insulating seat 56, a
plurality of openings 56b penetrating in the front-rear direction are formed.
[0005]
The inner circumferential surface of the head case 51 is threaded in the circumferential direction.
A ring member 61 whose outer peripheral surface is threaded is screwed into the inner
peripheral surface of the head case 51. When the ring member 61 abuts and presses the
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peripheral portion of the insulating seat 56, the insulating seat 56 is fixed.
[0006]
Further, as illustrated, a doughnut-shaped damper member 57 made of, for example, a felt
material is provided on the back surface of the insulating seat 56. The pipe portion 56 a is
inserted through the central opening of the damper member 57. Further, the opening 56 b of the
insulator 56 is covered by the damper member 57. Therefore, the damper member 57 functions
as an acoustic resistance material.
[0007]
Further, an adjustment nut 58 is disposed on the back side of the damper member 57. The
adjuster nut 58 is screwed into the threaded pipe portion 56a. That is, the damper member 57 is
compressed by turning the adjustment nut 58 in the tightening direction. Therefore, adjustment
of the acoustic resistance is possible by tightening and adjusting the adjuster nut 58. Further, a
lead wire 59 from the fixed pole is drawn into the pipe portion 56a. By inserting the conductive
pin member 60 into the pipe portion 56a, the fixed pole 55 and the pin member 60 are
electrically connected.
[0008]
Patent Document 1 similarly discloses a configuration in which a plurality of sound holes formed
in the insulating seat are covered with a sound resistance material, and the sound resistance
material is compressed with an adjustment nut from above.
[0009]
Unexamined-Japanese-Patent No. 2013-172391
[0010]
However, there is no quantitative indication in the adjustment method of the acoustic resistance
as in the configuration of FIG. 5, that is, the configuration in which the compression degree of the
acoustic resistance material is changed and adjusted depending on the pressing degree of the
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adjustment nut 58.
Therefore, adjustment based on the measurement results was necessary in the anechoic
chamber.
In addition, the adjustment work is not easy, and there is a problem that variation in
characteristics occurs due to the degree of skill of the worker or the like.
[0011]
The present invention has been made focusing on the above-mentioned points, and in a
unidirectional directivity condenser microphone unit having an acoustic terminal at the front and
back, adjustment of the acoustic resistance at the rear acoustic terminal can be easily performed,
and further An object of the present invention is to provide a condenser microphone unit capable
of reducing the variation in characteristics and improving the yield.
[0012]
In order to solve the above-described problems, a condenser microphone unit according to the
present invention is a condenser microphone unit in which a diaphragm that vibrates by sound
waves is disposed opposite to a fixed pole, and has acoustic terminals at the front and back. A
damper member provided on the rear side of the housing to form an acoustic resistance on the
rear acoustic terminal side, the damper member being accommodated in a cylindrical member
whose front end is in contact with the fixed electrode, and accommodated in the cylindrical
member And an acoustic resistance material formed by compression molding.
The damper member is preferably an electrode lead-out portion formed of a conductive material.
Further, it is preferable that the acoustic resistance material is made of plastically deformable
metal fiber. In the damper member, it is preferable that the acoustic resistance material is
exchangeably contained in the cylindrical member, and the acoustic resistance is changed by
exchanging the acoustic resistance material having different thicknesses. Further, in the damper
member, it is preferable that the degree of compression be increased by pushing the acoustic
resistance material accommodated in the cylindrical member to change the acoustic resistance.
[0013]
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As described above, according to the present invention, the acoustic resistance material is formed
by compressing the plastically deformable metal fiber, and the acoustic resistance material
having different thickness and degree of compression can be replaced, so that various directivity
can be obtained. It is possible to easily obtain a microphone unit having flexibility. That is, since
the damper member is constituted by the cylindrical member functioning as the electrode
drawing member and the acoustic resistance material accommodated in the cylindrical member,
the acoustic resistance material can be easily exchanged. Therefore, since directivity
characteristics can be changed by replacing the acoustic resistance material, workability can be
improved. Further, by preparing in advance acoustic resistance materials having different
thicknesses and compression degrees in accordance with directivity characteristics, it is possible
to reduce variations in characteristics in mass production and to improve yield.
[0014]
In a unidirectional directivity condenser microphone unit having an acoustic terminal in front
and rear, adjustment of the acoustic resistance at the rear acoustic terminal can be easily
performed, and furthermore, a capacitor that can reduce variations in characteristics and
improve yield A microphone unit can be obtained.
[0015]
FIG. 1 is a cross-sectional view of a unidirectional condenser microphone unit according to the
present invention.
2 (a) is a plan view of a damper member provided in the condenser microphone unit of FIG. 1,
and FIG. 2 (b) is a cross-sectional view of the damper member. Fig.3 (a) is a top view of the
modification of the damper member of FIG. 2, FIG.2 (b) is sectional drawing of the modification of
a damper member. FIGS. 4 (a) to 4 (c) are perspective views showing that there are a plurality of
types of thickness of the acoustic resistance material constituting the damper member provided
in the condenser microphone unit of FIG. FIG. 5 is a cross-sectional view of a conventional
unidirectional condenser microphone unit.
[0016]
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Hereinafter, embodiments of the present invention will be described based on the drawings. FIG.
1 is a cross-sectional view of a unidirectional condenser microphone unit according to the
present invention. The condenser microphone unit 1 includes a head case 2. The head case 2 is
formed in a cylindrical shape whose rear end side is opened, and an opening 2a is formed on the
front surface and an opening 2b is formed on the rear side surface. In the head case 2, a meshlike front mesh member 3 is provided on the rear side of the opening 2a, and on the rear side of
the front mesh member 3, a support ring 5 on which a diaphragm 4 is stretched is disposed.
There is. In addition, a disc-shaped fixed electrode 7 is disposed to face the diaphragm 4 via the
annular spacer 6. The fixed pole 7 is formed with a plurality of sound holes 7a.
[0017]
Further, a disc-shaped insulating seat (insulator) 8 is provided on the back side of the fixed
electrode 7. The peripheral edge portion of the insulating seat 8 stands frontward, and the
peripheral edge portion of the insulating pole 8 presses the peripheral edge of the fixed pole 7 to
the front side. Further, at the center of the insulating seat 8, a cylindrical pipe portion 8a erected
on the rear side is provided. The insulating seat 8 is fixed to the head case 2 by a ring member 9.
The inner peripheral surface of the head case 2 is threaded along the circumferential direction.
The outer peripheral surface of the ring member 9 is threaded so as to correspond to the inner
peripheral surface of the head case 2. By screwing the ring member 9 into the head case, the
peripheral edge of the insulating seat 8 is abutted against and pressed down, and the insulating
seat 8 is fixed to the head case 2.
[0018]
Further, as illustrated, in the pipe portion 8 a of the insulating seat 8, an electrode drawing
member and a cylindrical damper member 10 are mounted. The damper member 10 functions as
an acoustic resistance material. 2 (a) is a plan view of the damper member 10, and FIG. 2 (b) is a
cross-sectional view of the damper member 10. As shown in FIG. The damper member 10 is
composed of a cylindrical member 11 (cylindrical member) and a cylindrical acoustic resistance
material 12 accommodated in the cylindrical member 11. The cylindrical member 11 and the
acoustic resistance material 12 are formed of a conductive material, for example, a metal. That is,
when the front end of the cylindrical member 11 contacts the fixed electrode side, the electrode
is pulled out (electrically connected), and the acoustic resistance is adjusted by the acoustic
resistance material 12 accommodated therein. Ru.
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[0019]
The acoustic resistance material 12 is formed into a cylindrical shape by compressing metal
fibers capable of plastic deformation, for example, aluminum fibers. The acoustic resistance
material 12 corresponding to the desired directivity characteristic can be prepared in advance
depending on the amount and the degree of compression of the aluminum fiber. Further, since
the acoustic resistance material 12 can be plastically deformed, as shown in the plan view of FIG.
3A and the cross sectional view of FIG. Furthermore, the degree of compression can be increased.
Therefore, it is also possible to set the acoustic resistance value of the acoustic resistance
material 12 to a higher value, and to adjust in the direction of strengthening the directivity
characteristic.
[0020]
Furthermore, as shown in perspective views in FIGS. 4A to 4C, various directional characteristics
can be obtained by preparing a plurality of types of acoustic resistance materials 12 having
different heights (thicknesses) even with the same density. It is possible to realize a microphone
unit having the same. By fitting the acoustic resistance material 12 of a desired height into the
cylindrical member 11, the directivity characteristic of the microphone unit can be easily
changed. For example, to create a hypercardioid microphone unit, a damper member 10 with
high acoustic resistance is required. Therefore, as shown in FIG. 4A, a thick acoustic resistance
material 12 may be used. In addition, when preparing a plurality of types of acoustic resistance
material 12 having different heights as shown in FIGS. 4A to 4C, the upper surface side thereof is
accommodated in the cylindrical member 11 by marking such as color coding. Even if it is in an
abnormal state, it can be easily identified.
[0021]
As described above, according to the embodiment of the present invention, the acoustic
resistance material 12 is formed by compressing the plastically deformable aluminum fiber
(metal fiber), and the acoustic resistance material 12 having different thickness and degree of
compression is used. With the exchangeable configuration, microphone units having various
directional characteristics can be easily obtained. That is, since the damper member 10
functioning as the electrode drawing member and the acoustic resistance member is constituted
by the cylindrical member 11 and the cylindrical acoustic resistance material 12 accommodated
in the cylindrical member 11, the acoustic resistance is easily adjusted. Thus, the directivity
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characteristic of the microphone unit can be changed. Therefore, the workability concerning
production of the microphone unit can be improved. Further, by preparing in advance the
acoustic resistance materials 12 having different thicknesses and compression degrees in
accordance with directivity, variations in mass production can be reduced and yield can be
improved. As a result, mass production of stable quality condenser microphones is realized.
[0022]
In the above embodiment, the damper member 10 is constituted by the cylindrical member 11
and the cylindrical acoustic resistance material 12 accommodated therein, but the cylindrical
member is not limited to the cylinder, Moreover, the shape of the acoustic resistance material 12
accommodated in it may be used in accordance with the shape of the cylindrical member.
[0023]
Reference Signs List 1 condenser microphone unit 2 head case 3 front mesh member 4
diaphragm 5 support ring 6 spacer 7 fixed pole 8 insulator seat 9 ring member 10 damper
member 11 cylindrical member (cylindrical member) 12 acoustic resistance member
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