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JP2015231085

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DESCRIPTION JP2015231085
The present invention relates to characteristics of a driving force of a diaphragm and sound
collection characteristics in a high frequency band in a primary sound pressure gradient type
condenser microphone unit that drives the diaphragm by a difference in sound pressure applied
to acoustic terminals before and after the diaphragm. Adjust easily. A first pipe (3a) extending
forward on the front side of a diaphragm (10) and a second pipe (2b) disposed to surround the
first pipe are provided. A front acoustic terminal 31 communicating with the front surface of the
diaphragm is formed inside one of the two pipes, and inside the other pipe from the rear side of
the fixed pole 6 to the rear surface of the diaphragm A communicating rear acoustic terminal 32
is formed. [Selected figure] Figure 1
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, and more particularly to a primary
sound pressure gradient type condenser microphone unit for driving a diaphragm by the
difference in sound pressure applied to front and rear acoustic terminals.
[0002]
A primary sound pressure gradient type condenser microphone having an acoustic terminal
before and after the diaphragm drives the diaphragm with a difference in sound pressure applied
to the front and rear acoustic terminals.
03-05-2019
1
The upper limit of the force for driving the diaphragm (hereinafter referred to as driving force)
and the frequency at which sufficient driving force can be obtained is determined by the distance
between the acoustic terminals. That is, when the distance between the acoustic terminals is
short, operation is performed to a high frequency but the driving force of the diaphragm is low.
On the other hand, when the distance between the acoustic terminals is long, the opposite is true.
[0003]
As described above, the conventional primary sound pressure gradient type microphone has
mutually opposite characteristics regarding the driving force of the diaphragm and the sound
collection in the high frequency band. However, since these characteristics are determined at the
time of design of the microphone unit, there is a problem that it is not easy to adjust the
characteristics after formation of the unit. In order to solve the above-mentioned problem, the
distance between the front and rear acoustic terminals may be changed outside the primary
sound pressure gradient type microphone unit. That is, if a sound wave passage such as an
acoustic tube can be provided between the front and rear acoustic terminals and the length can
be changed, the distance between the front and rear acoustic terminals changes. As a result, it
becomes possible to easily adjust the characteristics of the driving force of the diaphragm and
the sound collection in the high frequency band. Also, primary sound pressure gradient
microphones are conventionally used as directional microphones. Therefore, it is desirable to be
able to adjust the directivity also in the primary sound pressure gradient microphone.
[0004]
In Patent Document 1, the applicant of the present invention attached baffles 52 to the
peripheral portion of the diaphragm 51 of the unidirectional capacitor microphone unit 50 as
shown in FIG. 5 and formed them on the outer frame 55 of the computer display panel A
structure is proposed in which sound waves received in the recess 55a and collected in the
recess 55a from the gap (side terminal) 54 outside the baffle 52 are collected at the rear acoustic
terminal 56 side.
[0005]
Patent No. 3975007
[0006]
03-05-2019
2
However, in the configuration disclosed in Patent Document 1, since the distance between the
front and rear acoustic terminals changes depending on the size (area) of the baffle, the diameter
(opening diameter) of the recess 55a of the panel outer frame must be changed as well. It also
greatly affects the design aspect.
In order to change the distance between the front and rear acoustic terminals without changing
the diameter of the opening that accommodates the unit, for example, a configuration as shown
in FIG. 6 can be considered.
An acoustic pipe 61 extending forward is provided on the front side of the microphone unit 60,
and the length of the acoustic pipe 61 is adjusted. In the case of FIG. 6, the wall 70 is provided
with an opening 70a, from which the microphone unit 60 is accommodated.
[0007]
However, in the case of this configuration, a passage as shown in FIG. 6 must be secured. That is,
the bottomed acoustic tube 63 is provided, and the unit and the acoustic tube 61 are disposed
therein. Also, it is necessary to secure a passage for the sound waves to go around the rear side
of the unit through the outside of the baffle plate 62. Therefore, since the passage of the sound
wave has a double structure to the rear side of the unit, a large space is required on the rear side
of the wall 70, and there is a problem that the structure becomes complicated.
[0008]
The present invention has been made focusing on the above points, and in a primary sound
pressure gradient type condenser microphone unit that drives the diaphragm by the difference in
sound pressure applied to the acoustic terminals before and after the diaphragm, the vibration is
generated. An object of the present invention is to provide a condenser microphone unit capable
of easily adjusting the driving force of a plate and the characteristics of sound collection in a high
frequency band.
[0009]
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3
In order to solve the problems described above, a condenser microphone unit according to the
present invention comprises a fixed pole in which a plurality of sound holes are formed, and a
diaphragm disposed at a predetermined distance from the fixed pole, A primary sound pressure
gradient type condenser microphone unit for driving the diaphragm by a difference in sound
pressure applied to the front and back of the diaphragm, wherein the first pipe extends forward
on the front side of the diaphragm; And a second pipe arranged to surround the first pipe and a
front sound communicating with the front surface of the diaphragm on the inside of one of the
first pipe and the second pipe. A terminal is formed, and a rear acoustic terminal communicating
with the rear surface of the diaphragm from the rear side of the fixed electrode is formed inside
the other pipe.
An opening corresponding to the position of the first pipe is formed in the diaphragm and the
fixed pole, and an insulating pipe made of an insulating material is inserted into the first pipe and
the opening. As a result, the front side and the rear side of the fixed pole are acoustically
separated, and a rear acoustic terminal is formed inside the first pipe, and the outside of the first
pipe and the inside of the second pipe Preferably, a front acoustic terminal is formed on the
[0010]
With this configuration, the distance between the front acoustic terminal and the rear acoustic
terminal (inter-terminal distance) changes only by changing the lengths of the first pipe and the
second pipe, and the driving force of the diaphragm Characteristic adjustment of sound
collection in a high frequency band can be easily performed. In addition, since the adjustment
can be performed within the range of the diameter of the unit, a space for the rear acoustic
terminal and other members are not required around the unit, and a simple installation can be
performed in a space-saving manner.
[0011]
Alternatively, only the first pipe extending forward of the diaphragm communicates with the
front surface of the diaphragm to form a front acoustic terminal inside the first pipe, and the
fixed electrode and the diaphragm A rear acoustic terminal which is a communication passage to
the rear side of the fixed pole outside the first pipe and inside the second pipe by being formed
to have a diameter smaller than the diameter of the second pipe. May be formed. With this
configuration, the same effect as that described above can be obtained.
03-05-2019
4
[0012]
In the primary sound pressure gradient type condenser microphone unit that drives the
diaphragm by the difference in sound pressure applied to the front and rear acoustic terminals of
the diaphragm, the characteristics of the driving force of the diaphragm and the sound collection
in the high frequency band are easily adjusted It is possible to obtain a condenser microphone
unit that can be
[0013]
FIG. 1 is a cross-sectional view of a condenser microphone unit according to the present
invention.
FIG. 2 is a cross-sectional view showing an application example of a condenser microphone unit
according to the present invention. FIG. 3 is a cross-sectional view showing another application
of the condenser microphone unit according to the present invention. FIG. 4 is a cross-sectional
view showing a modification of the condenser microphone unit according to the present
invention. FIG. 5 is a cross-sectional view showing an application example of a conventional
condenser microphone unit. FIG. 6 is a cross-sectional view showing another application of the
conventional condenser microphone unit.
[0014]
Hereinafter, embodiments of the present invention will be described based on the drawings. FIG.
1 is a cross-sectional view of a condenser microphone unit according to the present invention.
The condenser microphone unit 1 shown in FIG. 1 is disposed on the front opening side of the
housing 2 and a cylindrical housing 2 whose both end portions are open in the front-rear
direction (left side is front side and right side is back side in the drawing) A front lid 3 and a rear
lid 4 disposed on the rear opening side of the housing 2 are provided.
[0015]
The front lid portion 3 is formed with a pipe portion 3a (first pipe) having a predetermined
diameter and extending in a cylindrical shape in the axial direction at a central portion thereof.
03-05-2019
5
Further, a plurality of sound holes 3 b are provided in the lid portion around the pipe portion 3 a.
The peripheral edge of the front lid 3 abuts on the inner peripheral surface of the housing 2, but
the housing 2 projects further forward from that position, and a large diameter pipe portion 2b
(second pipe) is formed. There is. As a result, a sound wave passage communicating with the
sound hole 3 b is formed outside the pipe portion 3 a and inside the pipe portion 2 b, and this is
used as the front acoustic terminal 31. A flange portion 2a projecting inward is provided on the
inner peripheral surface on the front side of the housing 2, and a peripheral portion 3c of the
front lid 3 is locked to the inside of the flange portion 2a. There is.
[0016]
Further, on the back surface side (rear surface side) of the front lid portion 3, a recessed portion
3d formed in a wide annular shape around the pipe portion 3a is formed, and the annular
recessed portion 3d is a surface side (front surface side) It is in communication with the sound
hole 3b. Further, on the back surface side of the front lid portion 3, a diaphragm 10 in the form
of a film is attached so as to close the annular recess 3d. Further, at the central portion of the
diaphragm 10, an opening 10a having the same diameter as the inner diameter of the pipe
portion 3a is formed.
[0017]
In addition, a ring-shaped spacer 5 is disposed at the rear edge of the diaphragm 4. Furthermore,
on the rear side of the spacer 5, a disk-shaped fixed electrode 6 having a plurality of sound holes
6a is disposed. That is, the diaphragm 4 and the fixed electrode 6 are spaced apart by the height
of the spacer 5. An opening 6 b is formed at the center of the fixed electrode 6 in accordance
with the position and the inner diameter of the pipe 3 a as in the case of the diaphragm 4.
[0018]
Further, the fixed electrode 6 is held by a holding plate 7 whose peripheral portion is made of a
thick insulating material. A predetermined gap is formed between the fixed pole 6 and the
holding plate 7. The pipe portion 3a stacked in the front-rear direction at the center of the unit,
the opening 10a of the diaphragm 10, and the opening 6b of the fixed electrode 6 have the same
inner diameter. An insulating pipe 11 formed of an insulating material is inserted into the inner
diameter. Thereby, the front side and the rear side of the fixed pole 6 are acoustically separated.
03-05-2019
6
[0019]
With this configuration, the sound wave entering from the insulating pipe 11 in the pipe portion
3 a turns to the rear side of the fixed pole 6, passes through the sound hole 6 a of the fixed pole
6, and applies sound pressure to the rear side of the diaphragm 10. That is, the pipe portion 3 a
and the insulating pipe 11 function as the rear acoustic terminal 32. Moreover, according to such
a configuration, the inter-terminal distance between the front acoustic terminal 31 and the rear
acoustic terminal 32 can be changed by changing the length of the pipe portion 2b and the
length of the pipe portion 3a. Therefore, the characteristics of the driving force of the diaphragm
10 and the sound collection in the high frequency band can be easily adjusted according to the
use situation.
[0020]
In the holding plate 7, for example, an FET 8 which is an impedance converter is disposed. The
signal line 9 a is connected to the FET 8. The signal line 9 a is drawn to the fixed pole 6 side and
is further connected to the fixed pole 6. Also, the signal line 9 b is drawn from the FET 8 through
the opening 4 a formed in the back lid 4 to the rear side of the microphone unit. Further, as
shown in the drawing, a rear lid 4 is disposed on the rear surface side of the holding plate 7. The
rear lid 4 is fixed by caulking the peripheral edge portion of the rear surface to the inside of the
rear end opening of the housing 2.
[0021]
In the condenser microphone unit 1 configured in this way, for example, when embedding it in a
housing wall of a personal computer, as shown in FIG. 2, an opening 20a matched to the
diameter of the housing 2 is formed in the wall 20, and the condenser microphone The unit 1
may be fitted. In this way, as in the conventional configuration shown in FIG. 5, no space or other
members are required around the unit, so it can be realized with a space saving and a simple
configuration.
[0022]
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7
Further, according to this condenser microphone unit 1, as shown in FIG. 3, it is possible to
configure a close talk type microphone by connecting the coaxial acoustic tube 15 on the front
side. The coaxial acoustic tube 15 is a double structure of the outer acoustic tube 16 and the
inner acoustic tube 17. Furthermore, in this example, the acoustic resistance material 18 is
provided at the tip of the microphone. As shown in FIG. 3, the rear end of the inner acoustic pipe
17 is fitted on the circumferential surface of the pipe portion 3 a, and the rear end of the outer
acoustic pipe 16 is fitted on the front inner surface of the housing 2. As a result, the distance
between the front acoustic terminal and the rear acoustic terminal is increased, so that the sound
collection in the high frequency band is reduced, but the driving force of the diaphragm is
increased, and a close talk type microphone can be easily realized. .
[0023]
As described above, according to the embodiment of the condenser microphone unit of the
present invention, the small diameter pipe portion 3a communicating with the rear side of the
diaphragm 10 is provided on the front side of the unit, and the periphery of the pipe portion 3a
is A large diameter pipe portion 2b communicating with the front side of the diaphragm 10 is
provided so as to surround it. That is, a double pipe is provided on the front side of the unit, and
the rear acoustic terminal 32 is formed inside the small diameter pipe portion 3a, and the outside
of the small diameter pipe portion 3a and the inner diameter of the large diameter pipe portion
2b. The front acoustic terminal 31 is formed on the As a result, the distance between the front
acoustic terminal 31 and the rear acoustic terminal 32 changes only by changing the lengths of
the pipe portion 3a and the pipe portion 2b, and the characteristic adjustment of the driving
force of the diaphragm 10 and sound collection in the high frequency band It can be done easily.
In addition, since the adjustment can be performed within the range of the diameter of the unit, a
space for the rear acoustic terminal 32 and other members are not required around the unit, and
a simple and space-saving mounting is possible.
[0024]
Furthermore, the outer sound tube 16 and the inner sound tube 17 of FIG. 3 may be replaceable.
For example, in FIG. 3, the outer acoustic tube 16 can be easily changed by forming threads on
the outer side of the outer acoustic tube 16 and the inside of the housing 2 fitted thereto.
Similarly, the inner acoustic pipe 17 can be easily changed by forming a screw thread on the
inner side of the inner acoustic pipe and the pipe portion 3a fitted thereto. By using these modes,
it is possible to adjust the distance between the front and rear acoustic terminals. In addition,
03-05-2019
8
since the lengths of the outer acoustic tube 16 and the inner acoustic tube 17 can also be made
variable, adjustment of acoustic impedance (in particular, acoustic mass) is also possible.
[0025]
The fitting means of the outer sound tube 16 and the inner sound tube 17 is not limited to the
above-mentioned screw type fitting means. For example, fitting means called bayonet type or
other fitting means can be used.
[0026]
Furthermore, as in the example of FIG. 3, the location of the acoustic resistance material 18 is not
limited to the tip of the microphone. An acoustic resistance material may be disposed inside each
of the outer acoustic tube 16 and the inner acoustic tube 17. Further, as the acoustic resistance
material, felt material, sponge-like urethane, glass wool, aluminum fiber or the like can be used.
By doing this, the acoustic resistance material can be disposed on the sound wave path by a
simple method. Therefore, the directivity can be easily adjusted, and the adjustment of the
characteristics of the microphone corresponding to the installed place can be realized.
[0027]
Furthermore, the respective openings of the outer sound tube 16 and the inner sound tube 17
may have a horn shape. By providing the acoustic tube having such a shape, the driving force of
the diaphragm can be improved, and the configuration can also be used in a configuration using
a microphone unit with high mechanical impedance. The microphone unit with high mechanical
impedance is, for example, a microphone unit with high tension of the diaphragm, a microphone
unit with high acoustic impedance before and after the diaphragm, or the like.
[0028]
In the above embodiment, of the double pipes provided on the front side of the unit, the rear
acoustic terminal 32 is formed inside the small diameter pipe 3a, and outside thereof and inside
the large diameter pipe 2b. The front acoustic terminal 31 is to be formed. However, the
03-05-2019
9
condenser microphone unit according to the present invention is not limited to that form. For
example, the front acoustic terminal 31 and the rear acoustic terminal 32 can be reversed.
Specifically, it may be configured as shown in FIG. The configuration shown in FIG. 4 is largely
different from the configuration shown in FIG. 1 in the forms of the fixed electrode 6 and the
diaphragm 10. That is, in the fixed electrode 6 and the diaphragm 10 shown in FIG. 4, the
openings 6 b and 10 a are not provided at the center. Furthermore, the fixed electrode 6 and the
diaphragm 10 are formed to have a small diameter so as to be disposed inside the sound hole 3 b
provided in the front lid 3. The diameter of the ring-shaped spacer 5 is also adjusted to the
diameters of the fixed electrode 6 and the diaphragm 10, whereby a predetermined gap is
formed between the fixed electrode 6 and the diaphragm 10.
[0029]
With this configuration, the sound wave passing through the pipe portion 3a at the center of the
unit gives a sound pressure to the front side of the diaphragm 10, and the sound wave passing
through the inside of the pipe portion 2b outside the pipe portion 3a And the sound pressure is
applied to the rear surface side of the diaphragm 10. That is, the inside of the small diameter
pipe 3 a is the front acoustic terminal 31, and the inside of the large diameter pipe 2 b is the rear
acoustic terminal 32. With such a configuration, the same effect as the configuration shown in
FIG. 1 can be obtained.
[0030]
Reference Signs List 1 condenser microphone unit 2 housing 2 b pipe (second pipe) 3 front lid 3
a pipe (first pipe) 3 b sound hole 4 back lid 5 spacer 6 fixed pole 6 a sound hole 6 b opening 7
holding plate 10 Diaphragm 10a Opening 11 Insulating pipe 31 Front acoustic terminal 32 Rear
acoustic terminal
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