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DESCRIPTION JP2010154477

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DESCRIPTION JP2010154477
PROBLEM TO BE SOLVED: To provide a manufacturing method of a condenser microphone unit
keeping airtight a necessary place for preventing frequency response deterioration, a condenser
microphone unit manufactured by the manufacturing method, and a condenser microphone
mounted with the condenser microphone unit. SOLUTION: A unit case 2, a diaphragm 4, a
counter electrode 5, a hollow lead-out electrode 7 in contact with the counter electrode, and a
fixing plate 8 in contact with the lead-out electrode 7 and fitted to an end of the unit case.
Method of applying the adhesive 15 to the lead-out electrode 7, and in the unit case 2, the
diaphragm 4, the counter electrode 5, the lead-out electrode 7, and the fixing plate 8 in this
order. And a caulking process for caulking the fixing plate 8 so as to be stressed and flexed, and a
built-in assembling process; Is equipped. [Selected figure] Figure 1
Method of manufacturing condenser microphone unit, condenser microphone unit, and
condenser microphone
[0001]
The present invention relates to a method of manufacturing a condenser microphone unit, a
condenser microphone unit, and a condenser microphone, and in particular, to prevent
deterioration of the frequency response of a unidirectional condenser microphone unit, the
condenser keeping necessary places airtight. This embodiment is characterized by the method of
manufacturing the microphone unit.
[0002]
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A condenser microphone comprises a condenser microphone unit that constitutes a kind of
condenser in which a diaphragm that vibrates by sound waves and a fixed electrode (also called
"back electrode") are disposed opposite to each other via a spacer.
The condenser microphone unit is assembled in a unit case, and further includes an FET (field
effect transistor) as an impedance converter and a circuit board on which the FET is mounted.
[0003]
Among such condenser microphones, in the unidirectional condenser microphone, the diaphragm
is in communication with the outside of the microphone unit by the through holes provided
before and after the microphone unit, and the sound around the condenser microphone is
vibrated It is configured to be transmitted to the board.
[0004]
In the conventional unidirectional condenser microphone, the space in which the FET and the
capacitor are provided and the through hole are formed as separate spaces.
This is because the sound enters the space where the FET and the capacitor are provided from
the through hole, so that the space does not act as an acoustic mass, that is, operates as a
resonator and does not degrade the frequency response. It is for. As an example of the condenser
microphone of such a configuration, there is a condenser microphone described in Patent
Document 1.
[0005]
The condenser microphone unit shown in FIG. 9 is a condenser microphone unit in which a space
in which an FET or a condenser is provided and the through hole are formed as separate spaces,
as in the condenser microphone described in Patent Document 1.
[0006]
In FIG. 9, the cylindrical unit case 102 has an inward flange 121 at the front end (lower end in
FIG. 9).
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Further, an opening is provided at a central portion of the flange 121, and the opening forms a
front acoustic terminal 151. In the unit case 102, in order from the front end side, the diaphragm
holder 103, the diaphragm 104, the spacer (not shown), the counter electrode 105, the
insulating holder 106, the lead electrode 107, the sponge 110, the acoustic resistance material
109, and A plate 108 is fitted.
[0007]
The diaphragm 104 is made of, for example, a resinous thin film, and vibrates by receiving an
acoustic wave. The diaphragm holder 103 is a ring-shaped member, and the peripheral portion
of the diaphragm 104 is fixed to the back surface of the holder 103 with an appropriate tension.
The spacer intervenes between the diaphragm 104 and the counter electrode 105 to create a
space of a thickness of the spacer. The diaphragm 104 or the counter electrode 105 has a thin
layer of an electret element, that is, a polymer compound in which charges are semipermanently
stored, formed on the opposite surface thereof, and the diaphragm 104 and the counter
electrode 105 constitute a capacitor.
[0008]
The extraction electrode 107 is a conductive member formed in a funnel shape and having a
space communicating with the inside, and the wide port portion 174 faces downward, and the
counter electrode 105 is provided on a flange 176 provided on the peripheral portion of the
wide port portion 174. It is fitted in unit case 102 in the state where it abuts. The sponge 110
and the acoustic resistance material 109 placed on the sponge 110 are accommodated in a space
formed by the wide opening 174 and the counter electrode 105. The sponge 110 is compressed
from above and below by being pinched by the wide opening of the extraction electrode 107 and
the counter electrode 105, but the repulsive force of the sponge 110 against the compression
causes the acoustic resistance material 109 placed on the sponge 110. Is pressed against the
bottom of the wide opening 174.
[0009]
The insulating holder 106 is a cylindrical member fitted inside the unit case 102, and as
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described later, it is made of an insulating material for electrically insulating the unit case 102,
the counter electrode 105 and the lead electrode 107. Member. In the insulating holder 106, the
side wall becomes thinner at the position between the large diameter portion 162 where the side
wall becomes thinner at both ends and the inner diameter of the cylindrical internal space
becomes larger and the large diameter portion 162 at both ends. A small diameter portion 164 in
which the inner diameter of the space is reduced is formed. By inserting one large diameter
portion 162 into the gap formed by unit case 102, counter electrode 105 and lead electrode 107,
the above-described insulating state is formed, and at the same time, counter electrode 105 and
lead electrode are formed. 107 is fitted in the insulating holder 106 and fixed in the unit case
102.
[0010]
The fixed plate 108 is fitted in the cylindrical unit case 102 and fixed in the unit case 102 by
caulking the end of the unit case 102, and the diaphragm ring 103 housed in the unit case 102.
The diaphragm 104, the spacer, the counter electrode 105, the sponge 110, the acoustic
resistance material 109, and the lead-out electrode 107 are members that serve as a so-called lid
that holds the unit case 102 inside. The fixing plate 108 is provided with an opening, which
constitutes a rear acoustic terminal 181.
[0011]
The lead-out electrode 107 is in contact with the counter electrode 105 and electrically
connected integrally with the counter electrode 105, and constitutes one terminal of the abovedescribed capacitor configured of the diaphragm 104 and the counter electrode 105. The
diaphragm 104 is electrically connected to the unit holder 102 via the diaphragm holder 103,
and the unit holder 102 constitutes the other terminal of the capacitor.
[0012]
Since the counter electrode 105 is formed with an appropriate number of holes, the space
formed by the diaphragm 104 and the counter electrode 105 passes through the holes to form
the wide opening 174 of the lead electrode 107, the narrow opening 178, and the fixing plate
108. It communicates with the outside through the rear acoustic terminal 181 of the
[0013]
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As well known, when the diaphragm 104 receives a sound wave and vibrates, the capacitance of
the capacitor formed of the diaphragm 104 and the counter electrode 105 changes, and the
voltage of the voltage passes through the electric circuit 112 including an impedance conversion
circuit such as FET. An audio signal due to the change is output.
[0014]
In the condenser microphone having the configuration described above, the extraction electrode
107 separates the space 113 where the electric circuit 112 is provided, and the acoustic path
leading from the rear acoustic terminal 181 to the diaphragm 104 through the inside of the
extraction electrode 107. It is divided into spaces.
[0015]
JP, 2008-172413, A
[0016]
By the way, since it is generally difficult to completely eliminate fine irregularities on the surface
of a component when manufacturing a mechanical component, also in the condenser microphone
unit 100, the surfaces of these members are manufactured when producing the lead electrode
107 and the fixing plate 108. The fine unevenness remains in the
Therefore, as shown in FIG. 9, a minute gap 200 is generated between the lead-out electrode 107
and the fixed plate 108, and a voice is transmitted from the gap to the electric circuit housing
space 113 where the electric circuit 112 is provided. I get stuck.
[0017]
When a voice enters such a space, the space acts as an acoustic mass, and the space operates as
a resonator.
Hereinafter, the phenomenon will be described with reference to FIG. 9 and FIG.
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[0018]
In FIG. 9, the sound pressure applied from the front acoustic terminal 151 to the diaphragm 104
is P1, the stiffness of the diaphragm 104 is s0, the mass of the diaphragm 104 is m0, and it is
formed between the diaphragm 3 and the counter electrode 4 The resistance of the narrow gap
r0, the stiffness of the sponge 110 s1, the resistance of the acoustic resistance material 109 r1,
the mass of the electric circuit storage space 113 m2, the stiffness of the electric circuit storage
space 113 s2, vibration from the rear acoustic terminal 181 Assuming that the sound pressure
applied to the plate 104 is P2, the condenser microphone unit 100 is equivalent to the electric
circuit shown in FIG.
[0019]
As understood from the equivalent circuit shown in FIG. 10, the mass m2 of the electric circuit
housing space 113 and the stiffness s2 operate as a resonator.
This situation will be described with reference to FIG.
[0020]
FIG. 7 shows the frequency response of the condenser microphone unit, ie, the measured value of
the level of the output with respect to the frequency, and the respective curves are 0 °, ie, 90 °
when the microphone faces the measuring speaker, and The measured value when rotated 180
° is shown.
As shown in FIG. 7, in the conventional condenser microphone unit 100, there is a problem that
the frequency response of the condenser microphone unit 100, in particular, the frequency
response in the high range is deteriorated in all directions.
[0021]
The present invention has been made in view of the above problems, and in order to prevent
deterioration of the frequency response of a condenser microphone unit, in particular, a
unidirectional directivity condenser microphone unit, the electric circuit storage space is not It is
an object of the present invention to provide a method of manufacturing a condenser
microphone unit, a condenser microphone unit, and a condenser microphone which are isolated
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from space.
[0022]
According to the present invention, there is provided a cylindrical unit case having a free end, a
diaphragm which receives and vibrates a sound wave, a counter electrode disposed opposite to
the diaphragm and constituting a capacitor with the diaphragm, and the counter electrode. A
method of manufacturing a condenser microphone unit comprising: a hollow lead-out electrode
in contact with; and a fixing plate fitted to an end of the unit case while being in contact with the
lead-out electrode, A step of applying, a step of incorporating in the unit case, the diaphragm, the
counter electrode, the lead-out electrode on which the adhesive has evaporated, and the fixing
plate in this order from the open end; A plate, the counter electrode, the lead-out electrode on
which the adhesive is evaporated, and the release end of the unit case on which the fixing plate is
incorporated; And caulking caulking process to flex under force, the most important feature in
that it comprises.
[0023]
Although not particularly limited in the present invention, the above adhesive is a hot melt
adhesive, and a heating process for heating the condenser microphone unit after the caulking
process is completed to melt the hot melt adhesive; And cooling the completed condenser
microphone unit to cure the hot melt adhesive.
[0024]
Further, although not particularly limited in the present invention, the adhesive is a hot melt
adhesive diluted with an organic solvent, and the solvent contained in the hot melt adhesive
applied to the lead electrode is evaporated and cured. An evaporation process, a heating process
for heating the condenser microphone unit completed with the caulking process to dissolve the
hot melt adhesive, and a cooling process for cooling the condenser microphone unit completed
with the heating process to cure the hot melt adhesive It is preferable to further have a process.
[0025]
The present invention also provides a cylindrical unit case having an open end, a diaphragm that
receives and vibrates sound waves, and a counter electrode that is disposed opposite to the
diaphragm and that constitutes a capacitor with the diaphragm, and the counter electrode. A
condenser microphone unit comprising: a hollow lead-out electrode in contact with an electrode;
and a fixing plate fitted to an end of the unit case while in contact with the lead-out electrode, the
open end of the unit case By caulking, the diaphragm, the counter electrode, the lead electrode,
and the fixing plate are fixed in the unit case, and the contact portion between the lead electrode
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and the fixing plate is covered with a cured hot melt adhesive. It is characterized by
[0026]
The present invention is also characterized in that it is a condenser microphone provided with
the above-mentioned condenser microphone unit.
[0027]
According to the present invention, it is possible to prevent deterioration of the frequency
response of the condenser microphone unit, in particular, the unidirectional condenser
microphone unit, by keeping the necessary places airtight.
[0028]
Hereinafter, embodiments of the present invention will be described with reference to the
drawings.
[0029]
As shown in FIG. 1, the condenser microphone unit 1 according to the embodiment of the
present invention differs from the conventional condenser microphone unit 100 shown in FIG. 9
in that the contact point between the lead electrode 7 and the fixing plate 8 is covered with a hot
melt adhesive. It has a sealed configuration.
Thus, the air chamber 11 which is a space formed inside the extraction electrode 7 and the
electric circuit storage space 13 which is the space outside the extraction electrode 7 are
completely separated in the unit case 2. ing.
The other configuration is the same as that of the conventional condenser microphone unit 100,
and thus the detailed description of the configuration is omitted, and hereinafter, a method of
manufacturing the condenser microphone unit according to the present embodiment will be
described.
[0030]
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First, as shown in FIG. 2, the lead-out electrode 7, the acoustic resistance material 9, the sponge
10, and the counter electrode 5 are fitted in this order into the insulating holder 6 from the one
end of the insulating holder 6 which is a cylindrical member. The hot melt adhesive 15 is applied
to the end of the narrow end portion 78 of the lead-out electrode 7.
In the present embodiment, the hot melt adhesive 15 is a polyester-based hot melt adhesive that
is soluble in an organic solvent, and when applied to the lead-out electrode 7, becomes a paste
dissolved in the organic solvent. There is.
The hot melt adhesive 15 is cured by volatilization of the organic solvent, but also has a property
of melting by heating to a predetermined temperature or more even after curing, and curing
again by cooling to a temperature lower than the predetermined temperature. doing.
In the present embodiment, a hot melt adhesive having the predetermined temperature of about
150 ° C. is used.
[0031]
Next, as shown in FIG. 3, the organic solvent contained in the hot melt adhesive 15 applied to the
lead-out electrode 7 is volatilized to cure the paste-like hot melt adhesive 15.
The organic solvent is volatilized by leaving it at normal temperature for a predetermined time,
heating it at a temperature at which the hot melt adhesive 15 does not melt for a predetermined
time, or leaving it in a low pressure or vacuum for a predetermined time. be able to.
[0032]
Next, as shown in FIG. 3 and FIG. 4, the diaphragm attached to the diaphragm holder 3 and the
diaphragm holder 3 inside the unit case 2 from the open end where the flange 21 of the unit
case 2 is not formed. 4, the spacer 16, the counter electrode 5, the lead electrode 7, the acoustic
resistance material 9, the sponge 10, the insulating holder 6 in which the counter electrode 5 is
incorporated, and the fixing plate 8 are incorporated.
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At this time, in the insulating holder 6, the hot melt adhesive 15 applied to the lead-out electrode
7 incorporated therein is directed to the release end, and the hot melt adhesive 15 is attached to
the fixing plate 8 incorporated after the insulating holder 6. It is incorporated in unit case 2 so
that it may contact.
[0033]
Next, as shown in FIG. 5, the members incorporated in the unit case 2 are fixed in the unit case 2
by caulking the release end of the unit case 2.
The open end of the crimped unit case 2 pushes the outer peripheral edge of the fixing plate 8
inward of the unit case 2, and the center of the fixing plate 8 is applied to the end face of the
narrow end 78 of the lead electrode 7. The contact of the cured hot melt adhesive 15 causes the
fixing plate 8 to bend and squeeze in such a manner that the central portion thereof protrudes to
the outside of the unit case 2.
[0034]
Next, as shown in FIG. 6, the condenser microphone unit 1 in which the free end of the unit case
2 is crimped is heated to melt the hot melt adhesive 15 applied to the lead-out electrode 7 and
cured.
This heating is performed at a temperature which is equal to or higher than the melting point of
the hot melt adhesive and which does not damage parts such as the FET inside the condenser
microphone unit 1 for a predetermined time. By melting the hot melt adhesive 15 in this manner,
the force of the fixing plate 8 is released, and the narrow end portion 78 of the lead-out electrode
7 contacts the fixing plate 8. At this time, the force of the fixed plate 8 remains without being
completely released, and the extraction electrode 7 continues to receive the pressing force of the
fixed plate 8.
[0035]
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In the extraction electrode 7, the end surface of the narrow portion 78 can not be completely
planarized at the time of manufacture, and fine unevenness is generated. Among the
irregularities on the surface of the end of the narrow portion 78, a plurality of projecting
portions penetrate the melted hot melt adhesive 15 and come into contact with the fixing plate 8
to electrically connect the lead electrode 7 and the fixing plate 8 to each other. Contact is
established. Also, the peripheral part of the protruding part which establishes the contact is
covered by the melted hot melt adhesive 15.
[0036]
Next, by cooling the condenser microphone unit 1 in which the electrical contact between the
lead-out electrode 7 and the fixing plate 8 has been established, the melted hot melt adhesive 15
is cured again. By curing the hot melt adhesive 15, the contact portion between the lead
electrode 7 and the fixing plate 8 is completely sealed, and the air chamber 11, which is a space
formed inside the lead electrode 7, and the lead electrode 7 The electric circuit storage space 13
which is the external space is completely isolated in the unit case 2.
[0037]
The condenser microphone unit manufactured by the above-described manufacturing method is
mainly used in a unidirectional microphone. In such a condenser microphone, as shown in FIG. 1,
the contact portion between the lead-out electrode 7 and the fixing plate 8 is completely sealed
by the hot melt adhesive 15. As a result, the internal space of the lead-out electrode 7 and the
electric circuit housing space 13 are completely separated in the condenser microphone unit, and
the entry of sound from the inner space of the lead-out electrode 7 into the electric circuit
housing space 13 is prevented. Then, since the voice does not enter the electric circuit storage
space 13, the electric circuit storage space 13 does not act as an acoustic mass, and the electric
circuit storage space 13 does not act as a resonant circuit. Such effects of the condenser
microphone unit according to the present embodiment will be described in detail below.
[0038]
As shown in FIG. 1, the sound pressure applied from the front acoustic terminal 51 to the
diaphragm 4 is P1, the stiffness of the diaphragm 4 is s0, the mass of the diaphragm 4 is m0, and
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between the diaphragm 4 and the counter electrode 5 Assuming that the resistance of the
narrow gap formed is r0, the stiffness of the sponge 10 is s1, the resistance of the acoustic
resistance material 9 is r1, and the sound pressure applied to the diaphragm 4 from the rear
acoustic terminal 81 is P2. The microphone unit 1 is equivalent to the electric circuit (sound
equivalent circuit) shown in FIG. In the acoustic equivalent circuit shown in FIG. 11, unlike the
acoustic equivalent circuit according to the conventional condenser microphone unit shown in
FIG. 10, there is no portion constituted by m2 and s2 operating as a resonator. Therefore, as
shown in the frequency response diagram of FIG. 8, the frequency response in the high range is
improved as compared to that of the conventional condenser microphone unit shown in FIG. The
configuration other than the data in the frequency response diagram of FIG. 8 is the same as that
of FIG.
[0039]
In the present embodiment, a paste-like polyester hot melt adhesive dissolved in an organic
solvent is used as the hot melt adhesive 15. However, the present invention is not limited to such
an embodiment. For example, a solid hot melt adhesive containing almost no organic solvent may
be used after being dissolved with a glue gun or the like. In addition, a paste-like or solid hot-melt
adhesive containing a conductive carrier may be used.
[0040]
It is a longitudinal section showing an example of a condenser microphone unit concerning an
embodiment of the present invention. It is a longitudinal cross-sectional view which shows the
1st process of the manufacturing method of the condenser microphone unit concerning the
embodiment of the present invention. It is a longitudinal cross-sectional view which shows the
2nd process of the manufacturing method of the condenser microphone unit which concerns on
embodiment of this invention. It is a longitudinal cross-sectional view which shows the 3rd
process of the manufacturing method of the condenser microphone unit which concerns on
embodiment of this invention. It is a longitudinal cross-sectional view which shows the 4th
process of the manufacturing method of the condenser microphone unit which concerns on
embodiment of this invention. It is a longitudinal cross-sectional view which shows the 5th
process of the manufacturing method of the condenser microphone unit which concerns on
embodiment of this invention. It is a graph which shows the frequency response of the
conventional condenser microphone unit. It is a graph which shows the frequency response of
the condenser microphone unit concerning the embodiment of the present invention. It is a
longitudinal cross-sectional view which shows the example of the conventional condenser
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microphone unit. It is an acoustic equivalent circuit schematic of the conventional condenser
microphone unit. It is an acoustic equivalent circuit schematic of the condenser microphone unit
which concerns on embodiment of this invention.
Explanation of sign
[0041]
1,100 condenser microphone unit 2,102 unit case 3,103 diaphragm holder 4,104 diaphragm
5,105 counter electrode 6,106 insulating holder 7,107 lead electrode 8,108 fixing plate 9,109
acoustic resistance material 10, DESCRIPTION OF SYMBOLS 110 sponge 11, 111 air chamber
12, 112 electric circuit 13, 113 electric circuit storage space 15 hot melt adhesive 16 spacer
200 clearance
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