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DESCRIPTION JP2011049693

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DESCRIPTION JP2011049693
An object of the present invention is to prevent variations in sensitivity characteristics from
occurring even when a diaphragm microphone subassembly, a spacer and an annular member
are taken as a large number in a condenser microphone having a metal case. SOLUTION: When
cutting out a large number of upper units 14, each beam portion 122a of the diaphragm
subassembly assembly 122 and each beam portion of a spacer assembly 124 at the connection
position of the upper unit assembly 114. In a mode of cutting 124a, a concave groove 114a of a
predetermined width is formed on the upper surface of each band plate portion 126a of the
annular member assembly 126, and then each band plate portion 126a is cut at the central
portion of each concave groove 114a. Thereby, the upper end portion of the outer peripheral
surface 22a of the annular member 26 is formed as the cutaway portion 26c, and the tip end
surface of the projections 22b and 24b remaining on the outer peripheral surfaces 22a and 24a
of the vibrating membrane subassembly 22 and the spacer 24 is the cutaway portion 26c. And
the side surface 26c1 of the [Selected figure] Figure 7
Condenser microphone and method of manufacturing the same
[0001]
The present invention relates to a compact condenser microphone, and more particularly to a
condenser microphone having a metal case and a method of manufacturing the same.
[0002]
In general, in a small condenser microphone, a diaphragm subassembly in which a diaphragm is
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stretched and fixed on the lower surface of a support ring and a back electrode plate face each
other through an annular spacer with the back electrode plate facing down. The capacitor
structure portion is configured by being arranged to face each other.
In this case, the capacitor structure is often configured to be covered from above by a metal case.
[0003]
In such a condenser microphone, for example, as described in “Patent Document 1”, the back
electrode plate is set to an outer peripheral surface smaller than the diaphragm subassembly and
the spacer, and the back electrode plate is surrounded. The annular member is disposed to be
substantially inscribed in the circumferential wall of the metal case, and the annular member
supports the outer peripheral edge of the spacer from the lower side.
[0004]
On the other hand, in a small condenser microphone having a substantially rectangular outer
shape in plan view, for example, as described in "Patent Document 2", the spacer etc. may be cut
out from a single sheet in a large number of pieces It has been done.
JP, 2004-254253, A JP, 2008-141289, A
[0005]
Even in a condenser microphone having a metal case, when the metal case has a substantially
rectangular outer shape in plan view, the outer shapes of the diaphragm subassembly, the spacer,
and the annular member can also be set substantially in a rectangular shape. Therefore, it
becomes relatively easy to form them by cutting them out of one sheet in a large number.
[0006]
At this time, three sheets for cutting out these are bonded in advance in a laminated state, and a
plurality of upper units consisting of a diaphragm subassembly, a spacer and an annular member
are cut out from this laminated sheet. Then, by incorporating this cut out upper unit into the
metal case, it is possible to arrange the vibrating membrane subassembly and the spacer in a
state of being positioned at a predetermined position.
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[0007]
However, in this case, there are the following problems.
[0008]
That is, the metal case is a press-formed product, and a corner R is unavoidably formed at the
connection portion between the circumferential wall and the upper surface wall.
On the other hand, in each sheet for cutting out the diaphragm subassembly and the spacer, if
the outer peripheral surface shape of the diaphragm and the spacer is formed smaller than the
outer peripheral surface of the annular member, it is cut out. In the upper unit, the outer
peripheral surface of each of the diaphragm subassembly and the spacer can be prevented from
interfering with the upper corner portion of the metal case in most part.
[0009]
However, since the sheet for cutting out the vibrating membrane subassembly is configured as a
vibrating membrane subassembly assembly in which a plurality of vibrating membrane
subassemblies are connected via the beam portion, the outer peripheral surface shape of the
vibrating membrane subassembly is Even if the beam portion is smaller than the outer peripheral
surface shape of the annular member, the tip end surface of the beam unit is flush with the outer
peripheral surface of the annular member in the cut out upper unit, and the upper corner of the
metal case It will interfere with the department.
The same applies to the sheet for cutting out the spacer.
[0010]
Then, when such interference occurs, the diaphragm subassembly and the spacer are deformed
to cause variations in the tension of the diaphragm, which causes a problem in that the
sensitivity characteristic of the condenser microphone is also varied. .
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[0011]
The present invention has been made in view of such circumstances, and in a condenser
microphone having a metal case, a diaphragm subassembly, a spacer and an annular member
thereof are formed by cutting out as a plurality of upper units. It is an object of the present
invention to provide a condenser microphone capable of preventing variations in sensitivity
characteristics from occurring, and a method of manufacturing the same.
[0012]
The present invention achieves the above object by devising the configuration of the diaphragm
subassembly, the spacer and the annular member.
[0013]
That is, in the condenser microphone according to the present invention, a diaphragm
subassembly in which a diaphragm is stretched and fixed on the lower surface of a support ring,
and a back electrode plate having an outer peripheral surface smaller than the diaphragm
subassembly A capacitor structure portion disposed oppositely with an annular spacer having an
outer peripheral surface larger than the back electrode plate, with the back electrode plate facing
down, an outer peripheral edge of the spacer around the back electrode plate A condenser
microphone comprising: an annular member supporting the lower part from the lower side; and a
metal case accommodating the capacitor structure part and the annular member so as to cover
the annular member from the upper side, the vibrating membrane subassembly being joined to
the spacer And the spacer is joined to the annular member, and the metal case is flat. The outer
peripheral surface of the annular member has four vertical flat portions substantially inscribed in
the circumferential wall of the metal case, and the upper end of each of the vertical flat portions
The portion is formed as a cut portion cut along the circumferential direction of the vertical flat
portion, and the vibrating membrane subassembly and the spacer both have outer peripheral
surface shapes smaller than the annular member. A protrusion is formed at a position
corresponding to each of the vertical flat portions on the outer peripheral surface of each of the
diaphragm subassembly and the spacer, and the tip end surface of each of the protrusions is a
side surface of each of the cut portions. It is characterized in that it is formed flush.
[0014]
In the above configuration, the term indicating the directivity such as "lower surface" or "lower"
is used for the sake of convenience to clarify the positional relationship between the members
constituting the condenser microphone, and thereby the condenser microphone There is no
limitation on the directionality when actually using.
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[0015]
The specific shape or size of the cross-sectional shape is not particularly limited as long as the
“cut-off portion” is cut along the circumferential direction at the upper end portion of each
vertical flat portion.
[0016]
The specific formation positions of the “projections” of the vibrating membrane subassembly
are not particularly limited as long as they are formed at positions corresponding to the vertical
flat portions.
[0017]
The same applies to each "protrusion" of the spacer.
In this case, each "protrusion" of this spacer may be formed at the same position as each
"protrusion" of the vibrating membrane subassembly, but it is of course in a different position. It
may be.
[0018]
On the other hand, a method of manufacturing a condenser microphone according to the present
invention is a method of manufacturing the condenser microphone, comprising: a diaphragm
subassembly assembly in which a plurality of the diaphragm subassemblies are connected to
each other via beams. A spacer assembly in which a plurality of the spacers are connected to
each other via a beam and an annular member assembly in which a plurality of the annular
members are connected to each other via a band plate are manufactured respectively. By joining
together the vibrating membrane subassembly assembly, the spacer assembly, and the annular
member assembly in a stacked state from the top in this order, a plurality of upper units
consisting of the vibrating membrane subassembly, the spacer and the annular member are
provided. The upper unit assembly connected to each other is manufactured, and then this upper
unit assembly is A predetermined width is provided on the upper surface of each band plate
portion of the annular member assembly in a mode in which each beam portion of the vibrating
membrane subassembly assembly and each beam portion of the spacer assembly are cut at a
connection position between upper units. The plurality of upper units are cut out by forming the
concave grooves and then cutting the band portions at the central portions of the concave
grooves.
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[0019]
The specific width and the formation range of the “strip plate” are not particularly limited as
long as the “strip plate” is formed in a strip shape wider than the “beams”.
[0020]
The specific cross-sectional shape is not particularly limited as long as the "dwelling groove
having a predetermined width" has a width capable of cutting the band plate portion at the
central portion of the recessed groove.
[0021]
As shown in the above configuration, in the condenser microphone according to the present
invention, since the metal case has a substantially rectangular outer shape in a plan view, the
outer shape of the diaphragm subassembly, the spacer, and the annular member as well. It is
possible to set the shape to a substantially rectangular shape.
Therefore, it becomes possible to easily cut out the diaphragm subassembly, the spacer and the
annular member from the three stacked sheets as a top unit in a large number of sections.
[0022]
And since the outer peripheral surface of the annular member of the upper unit cut out in this
way has four vertical flat portions substantially inscribed in the peripheral wall of the metal case,
the cut out upper unit is made of metal By being incorporated in the case, it becomes possible to
arrange the vibrating membrane subassembly and the spacer in a state of being positioned at a
predetermined position in the metal case.
[0023]
At that time, the upper end portion of each vertical flat portion on the outer peripheral surface of
the annular member is formed as an excavated portion cut along the circumferential direction,
while the vibrating membrane subassembly and the spacer are both obtained from the annular
member In addition, each of the projections is formed at the position corresponding to each
vertical flat portion on the outer peripheral surface of each outer peripheral surface, and each of
the projections has its tip end Since the surface is formed flush with the side surface of each cut
portion, the outer peripheral surface of each of the diaphragm subassembly and the spacer
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covers the entire circumference of the metal case when the upper unit is incorporated in the
metal case. Interference with the upper corner of the
[0024]
Therefore, it is possible to prevent in advance the occurrence of such interference, resulting in
deformation of the diaphragm subassembly and the spacer, and variations in the tension of the
diaphragm, so that the sensitivity characteristics of the condenser microphone can be obtained.
Variation can be prevented in advance.
[0025]
As described above, according to the present invention, in a condenser microphone having a
metal case, even when the diaphragm subassembly, the spacer and the annular member are
formed by cutting out as a plurality of upper units, sensitivity characteristics Variation can be
prevented in advance.
[0026]
On the other hand, in the method of manufacturing a condenser microphone according to the
present invention, the upper unit is formed by joining together the diaphragm subassembly
assembly, the spacer assembly and the annular member assembly manufactured in advance in
this order from above. The upper unit assembly is formed by connecting a plurality of
interdigitated members, and then, with respect to the upper unit assembly, each beam portion of
the diaphragm subassembly assembly and the spacer assembly at the connection position
between the upper units. By cutting each beam portion of the body, a recessed groove having a
predetermined width is formed on the upper surface of each band plate portion of the annular
member assembly, and thereafter, each band plate portion is cut at the central portion of each
recessed groove Since the plurality of upper units are cut out, the beam section cut on the outer
peripheral surface of each of the vibrating membrane subassembly and the spacer by a simple
process. The distal end surface of the projecting portion remains as a base end portion can be
formed in a side surface flush with the cut portion formed on the upper end of the annular
member.
[0027]
Then, by incorporating the upper unit cut out in this manner in the metal case, it is possible to
obtain a condenser microphone without variations in sensitivity characteristics.
[0028]
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When the upper unit is assembled in the metal case, it is possible to drop the upper unit in the
metal case with the metal case upside down, with the metal case placed upside down.
By doing so, the process of assembling the condenser microphone can be simplified.
Also in this case, the upper unit is incorporated with its annular member substantially inscribed
in the circumferential wall of the metal case, so that the spacer and the annular member are
positioned at a predetermined position in the metal case. It can be arranged.
[0029]
In the condenser microphone according to the present invention, if the cut portions formed at the
upper end portions of the vertical flat portions on the outer peripheral surface of the annular
member are set to have a substantially L-shaped cross section, the manufacturing process When
forming a ditch with a predetermined width on the upper surface of each band plate portion of
the annular member assembly, it is possible to use a normal rotary blade whose both side
surfaces are substantially parallel.
[0030]
Side cross sectional view showing the condenser microphone according to an embodiment of the
present invention disposed upwards, the condenser microphone being disassembled into main
components and a perspective view seen obliquely from above The condenser microphone is
disassembled into main components 1 is a detailed perspective view of FIG. 1 as viewed obliquely
from below; FIG. 1 is a sectional view showing the process of assembling the condenser
microphone; FIG. 7 is a plan view showing the process of manufacturing the upper unit of the
condenser microphone; Figure
[0031]
Hereinafter, embodiments of the present invention will be described using the drawings.
[0032]
FIG. 1 is a side sectional view showing a condenser microphone 10 according to an embodiment
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of the present invention in a state of being disposed upward.
FIGS. 2 and 3 are perspective views showing the condenser microphone 10 disassembled into
main components and viewed obliquely from above and from below, respectively.
[0033]
As shown in these figures, the condenser microphone 10 according to the present embodiment is
a small electret condenser microphone, and the upper unit 14, the back electrode plate 16, the
contact spring 18, and the lower unit 20 are provided in the metal case 12. It has been housed.
[0034]
The metal case 12 is a cap-like member having a substantially rectangular outer shape of about 3
× 4 mm in a plan view, and is formed by pressing a metal plate (for example, an aluminum
plate).
[0035]
A sound hole 12a is formed in the upper surface wall 12A of the metal case 12, and extension
pieces 12b extending downward and extending from the lower end edge of four vertical flat
portions in the circumferential wall 12B. Are formed respectively.
The metal case 12 is crimped to the lower unit 20 at the four extension pieces 12b.
[0036]
The upper unit 14 comprises a diaphragm subassembly 22, an annular spacer 24 adhesively
fixed to the lower surface of the diaphragm subassembly 22, and an annular member 26
adhesively fixed to the lower surface of the spacer 24.
[0037]
The vibrating membrane subassembly 22 has a vibrating membrane 28 stretched and fixed on
the lower surface of the support ring 30.
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[0038]
The vibrating film 28 has a metal deposition film formed on the upper surface of a polymer film
having a thickness of about 1.5 to 3 μm.
[0039]
The support ring 30 is made of a thin metal plate having a thickness of about 50 μm.
The outer peripheral surface shape of the support ring 30 is set to a substantially rectangular
shape which is slightly smaller than the peripheral surface wall 12B of the metal case 12, and the
inner peripheral surface shape is set to a substantially elliptical shape extending in the
longitudinal direction of the metal case 12 It is done.
[0040]
The spacer 24 is made of a thin metal plate having a thickness of about 25 μm.
The outer peripheral surface shape of the spacer 24 is set to the same shape as the outer
peripheral surface shape of the support ring 30, and the inner peripheral surface shape is set to
substantially the same shape as the inner peripheral surface shape of the support ring 30 There
is.
[0041]
The annular member 26 is a substantially rectangular annular member that supports the outer
peripheral edge of the spacer 24 from the lower side around the back electrode plate 16 and is
configured as an insulating substrate having a thickness of about 0.3 mm.
[0042]
The annular member 26 is formed such that its outer circumferential surface 26 a is
substantially inscribed in the circumferential surface wall 12 B of the metal case 12.
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Specifically, the outer peripheral surface 26 a of the annular member 26 is formed such that the
four vertical flat portions extend along the four vertical flat portions in the peripheral wall 12 B
of the metal case 12.
The upper end portion of each of the vertical flat portions is formed as a cut portion 26c cut in a
substantially L-shaped cross section along the circumferential direction of the vertical flat
portion.
The cutout 26c and its peripheral structure will be described in detail later.
[0043]
The inner peripheral surface 26b of the annular member 26 has a substantially oval shape
extending in the longitudinal direction of the metal case 12 in a plan view.
At this time, the inner peripheral surface 26b of the annular member 26 substantially coincides
with the position of the inner peripheral surface of the spacer at both end positions in the
longitudinal direction and both end positions in the orthogonal direction, but at the four corner
positions The diameter is larger than the position of the inner peripheral surface of the spacer
24.
[0044]
The back electrode plate 16 is composed of an electrode plate main body 16A made of a metal
plate having a thickness of about 0.1 mm, and an electret layer 16B disposed on the upper
surface of the electrode plate main body 16A. Holes 16a are formed.
At that time, the electret layer 16B is generated by performing polarization processing with a
predetermined charge voltage on an insulating film with a film thickness of about 10 to 30 μm
formed on the upper surface of the electrode plate main body 16A. A potential is applied.
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[0045]
The back electrode plate 16 has a substantially rectangular outer shape with corners R given to
the four corners in a plan view, and the outer peripheral surface thereof is substantially internal
to the inner peripheral surface 26 b of the annular member 26 at a plurality of locations. It is
arrange | positioned in the inner peripheral side space of the annular member 26 in the state
made to contact.
At this time, the back electrode plate 16 is in contact with the four corners of the lower surface
of the spacer 24 at the four corners of the upper surface thereof.
[0046]
The electret layer 18B of the back electrode plate 16 and the vibrating film 28 are disposed
opposite to each other with the spacer 24 interposed therebetween, whereby the capacitor
structure C is configured.
[0047]
Lower unit 20 includes a circuit board 32 disposed in parallel to electret layer 16 B, an
impedance conversion element 34 mounted substantially at the center of the upper surface of
circuit board 32, and a portion of circuit board 32 surrounding impedance conversion element
34. It consists of an annular substrate 36 mounted and fixed on the upper surface.
[0048]
The lower unit 20 is in contact with the lower surface of the annular member 26 in the upper
unit 14 on the upper surface of the annular substrate 36, and in this state, each extension piece
12b of the metal case 12 is on each side of the circuit board 32. It is fixed by caulking.
[0049]
A circuit board 32 has an insulating substrate having an outer peripheral surface shape
substantially the same as that of the annular member 26, and a conductive layer is formed on
both upper and lower surfaces and in the middle thereof in a predetermined pattern. It is a
structure.
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At this time, a part of the conductive layer formed on the upper surface of the circuit board 32
constitutes a first conductive layer 32 a electrically connected to the input terminal 34 a of the
impedance conversion element 34.
[0050]
The impedance conversion element 34 is configured as an IC chip having a flat rectangular
external shape, and has a rectangular shape slightly longer in the longitudinal direction of the
metal case 12 in a plan view.
The upper surface of the impedance conversion element 34 is located at a height of about 0.4
mm from the upper surface of the circuit board 32.
[0051]
The annular substrate 36 has a configuration in which conductive layers are formed in
predetermined patterns on both upper and lower surfaces of an insulating substrate having a
thickness of about 0.3 mm having the same outer peripheral surface shape as the circuit
substrate 32. There is.
[0052]
The inner circumferential surface 36 b of the annular substrate 36 has a substantially oval shape
extending in the longitudinal direction of the metal case 12 in a plan view.
In this case, the substantially oval shape forming the inner circumferential surface 36b partially
overlaps each other at the center of the annular substrate 36 and on both sides in the
longitudinal direction of the three circular cylinders having a diameter larger than the lateral
width of the impedance conversion element 34. It has a shape that is arranged in an overlapping
state.
[0053]
A second conductive layer 36c electrically connected to the first conductive layer 32a of the
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circuit board 32 is formed on the inner peripheral surface 36b of the annular substrate 36 so as
to extend from the lower surface to the upper surface of the annular substrate 36.
[0054]
The second conductive layer 36 c is formed to extend along the inner circumferential surface 36
b of the annular substrate 36 at two places on both sides of the impedance conversion element
34 as a part of the conductive through holes.
That is, after forming a conductive through hole in the center of the annular substrate 36, the
second conductive layer 36c is formed by drilling a through hole having a diameter slightly
larger than that of the conductive through hole on both sides in the longitudinal direction
thereof. It is formed by partially cutting off the conductive through hole.
[0055]
The contact spring 18 is disposed below the back electrode plate 16 so as to elastically press the
back electrode plate 16 upward.
[0056]
The contact spring 18 is a metal plate spring and is formed by pressing a plate spring material
having a plate thickness of about 50 μm.
[0057]
The contact spring 18 is formed in a substantially rectangular ring shape in plan view in a noload state.
At this time, the longitudinal central portion 18A of the contact spring 18 extends in the
horizontal direction, but the longitudinal end portions 18B extend linearly and obliquely upward.
Further, four spherical convex portions 18 a protruding downward are formed at predetermined
intervals in the longitudinal direction at the longitudinal central portion 18 A of the contact
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spring 18.
Further, at the both end portions 18B in the longitudinal direction of the contact spring 18, four
spherical convex portions 18b projecting upward are respectively formed at four corners.
[0058]
In a state in which the contact spring 18 is incorporated as a part of the condenser microphone
10, the inner peripheral space of the annular member 26 in a state where the outer peripheral
surface thereof is substantially inscribed in the inner peripheral surface 26b of the annular
member 26 It comes to be placed in
In this state, the contact spring 18 is in a state in which the longitudinal central portion 18A and
the pair of longitudinal end portions 18B extend substantially along the same horizontal plane
due to the bending deformation in the vertical direction.
[0059]
At this time, the contact spring 18 is in contact with the lower surface of the back electrode plate
16 at the four spherical convex portions 18b located at the upper end portion thereof, and the
four spherical convex portions 18a located at the lower end portion , And a portion of the upper
surface of the annular substrate 36 in the pair of second conductive layers 36c.
The contact spring 18 and the first and second conductive layers 32a and 36c electrically
connect the back electrode plate 16 and the input terminal 34a of the impedance conversion
element 34.
[0060]
In the contact spring 18, the formation positions of the respective spherical convex portions 18a
are set such that the four spherical convex portions 18a reliably abut on the pair of second
conductive layers 36c two by two. .
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Further, in the contact spring 18, the four spherical convex portions 18b are in contact with the
lower surface at the four corners of the back electrode plate 16 (that is, the portion where the
back electrode plate 16 is in contact with the spacer 24). It has become.
[0061]
Next, the detailed structure of the upper unit 14 will be described.
[0062]
FIG. 4 is a detailed view of the IY section of FIG.
[0063]
As shown in the figure, and as described above, the upper end portions of the four vertical flat
portions in the outer peripheral surface 26a of the annular member 26 are respectively formed
as cut portions 26c having a substantially L-shaped cross section. Each cut portion 26c is formed
to have a depth of about 0.2 mm and a width of about 0.1 mm.
[0064]
Further, as described above, the diaphragm subassembly 22 and the spacer 24 have the same
outer peripheral surface shape, and the outer peripheral surface shape is set to a substantially
rectangular shape which is slightly smaller than the peripheral wall 12 B of the metal case 12.
ing.
[0065]
Specifically, in the outer peripheral surfaces 22a and 24a of the vibrating film subassembly 22
and the spacer 24, portions corresponding to the vertical flat portions in the outer peripheral
surface 26a of the annular member 26 are slightly smaller than the side surface 26c1 of the
cutout portion 26c. The inner peripheral side is formed as a vertical flat portion extending in
parallel to the side surface 26c1.
Further, protrusions 22b and 24b protruding outward are formed at circumferentially central
portions of the vertical flat portions of the outer peripheral surfaces 22a and 24a of the
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diaphragm subassembly 22 and the spacer 24, respectively.
At that time, the front end surfaces of the respective projections 22b and 24b are formed flush
with the side surface 26c1 of the respective cut-out portions 26c.
[0066]
The connection portion between the upper surface wall 12A and the circumferential surface wall
12B of the metal case 12 is formed as an upper corner portion 12c having a corner R.
At that time, the upper surface wall 12A is formed such that the lower surface of the peripheral
portion 12d close to the upper corner portion 12c is displaced slightly upward than the other
portions.
[0067]
The side surface 26c1 of each cut-out portion 26c of the annular member 26 is formed at
substantially the same position in plan view as the end portion of the upper corner 12c of the
metal case 12 on the upper surface wall 12A side (that is, the R stop position). ing.
As a result, the projection 22 b of the diaphragm subassembly 22 is disposed slightly away from
the lower surface of the peripheral portion 12 d of the upper surface wall 12 A of the metal case
12.
[0068]
FIG. 5 is a side sectional view showing the process of assembling the condenser microphone 10.
[0069]
As shown in the figure, the assembly of the condenser microphone 10 is performed as follows.
[0070]
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That is, first, the metal case 12 is placed upside down, and the upper unit 14 turned upside down
is dropped into the space on the inner peripheral side of the circumferential wall 12 B of the
metal case 12. The support ring 30 is brought into surface contact with the lower surface of the
upper surface wall 12A.
At that time, the upper unit 14 is straightly installed with the annular member 26 substantially
inscribed in the circumferential wall 12 B of the metal case 12, so that the spacer 24 and the
annular member 26 are positioned at predetermined positions in the metal case 12. Will be
placed in the
[0071]
Next, the upside-down back electrode plate 16 and the contact spring 18 are sequentially
dropped into the metal case 12 so as to be located in the inner peripheral space of the annular
member 26 in the upper unit 14.
At this time, the contact spring 18 is in contact with the lower surface of the back electrode plate
16 at the four spherical convex portions 18 b.
[0072]
Next, the lower unit 20 is dropped into the metal case 12, and the pair of second conductive
layers 36 c formed on the upper surface of the annular substrate 36 is brought into contact with
the four spherical convex portions 18 a formed on the contact spring 18. Get in touch.
Then, from this state, while bending the contact spring 18, the lower unit 20 is pushed
downward to a position where the upper surface of the annular substrate 36 abuts on the lower
surface of the annular member 26 in the upper unit 14.
[0073]
Next, each extension piece 12b of the metal case 12 is bent to the inner peripheral side as shown
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by a two-dot chain line in the drawing, whereby each side portion of the circuit board 32 with
respect to the lower unit 20 pressed to the above position. The respective extension pieces 12b
are fixed by caulking.
[0074]
6 is a plan view showing the manufacturing process of upper unit 14, and FIG. 7 is a detailed
sectional view taken along line VII-VII.
[0075]
As shown in these figures, the upper unit 14 is manufactured as follows.
[0076]
First, as shown in FIG. 6 and FIG. 7A, a sheet shape in which a plurality of diaphragm
subassemblies 22 (see FIG. 7C) are connected to each other through beam portions 122a in two
orthogonal directions. And a plurality of sheet-like spacer assemblies 124 formed by connecting
the diaphragm subassembly assembly 122 and the plurality of spacers 24 (see FIG. 7C) in two
orthogonal directions via the beam portion 124a, and A sheet-like annular member assembly
126 is produced, in which the annular members 26 (see FIG. 7C) are connected to each other in
the two orthogonal directions via the band plate portion 126a.
[0077]
Then, by joining the vibrating membrane subassembly assembly 122, the spacer assembly 124
and the annular member assembly 126 in a stacked state from the top in this order, the plurality
of upper units 14 mutually cross in two orthogonal directions. The upper unit assembly 114
connected is produced.
[0078]
Next, the upper unit assembly 114 is annularly cut in such a manner as to cut each beam portion
122a of the vibrating membrane subassembly assembly 122 and each beam portion 124a of the
spacer assembly 124 at the connection position between the upper units 14. A recessed groove
114 a of a predetermined width is formed on the upper surface of each strip plate portion 126 a
of the member assembly 126.
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At this time, these concave grooves 114a are formed to have a width of about 0.4 mm and a
depth of about 0.2 mm using a relatively wide rotary blade 102 shown by a two-dot chain line in
FIG. 7A.
[0079]
Incidentally, prior to the formation of the respective concave grooves 114a, as shown in FIG. 6,
four small circles are provided around the great circle at the positions of the respective grid
points between the upper units 14 arranged in the two orthogonal directions. Through holes
114b having a planar shape arranged in a cross are formed by drilling.
Each concave groove 114a is formed with a width shown by a broken line in the figure between
two adjacent through holes 114b.
[0080]
Next, as shown in FIG. 7 (b), each band plate portion 126a of the annular member assembly 126
is cut at the central portion of each concave groove 114a, as shown in FIG. 7 (c), Cut out the
upper unit 14 of
Cutting of each of the band plate portions 126a is performed with a cutting width of about 0.2
mm using a relatively narrow rotary blade 104 shown by a two-dot chain line in FIG. 7B.
The cut surface of each of the band plate portions 126a is formed between the two adjacent
through holes 114b in FIG. 6 so as to have a width shown by a two-dot chain line narrower than
the width shown by the broken line.
[0081]
In each upper unit 14 cut out in this manner, as shown in FIG. 7C, the tip end surfaces of the
projections 22b and 24b of the vibrating membrane subassembly 22 and the spacer 24 are cut
portions of the annular member 26. It forms flush with side 26c1 of 26c.
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[0082]
As described above in detail, the condenser microphone 10 according to the present embodiment
has the outer shape of the metal case 12 in a substantially rectangular shape in plan view, so the
diaphragm subassembly 22, the spacer 24 and the annular member The external shape of the
reference numeral 26 can also be set to a substantially rectangular shape.
Therefore, it is possible to easily cut out the diaphragm subassembly 22, the spacer 24 and the
annular member 26 from the stacked three sheets as the upper unit 14 in large numbers.
[0083]
The upper unit 14 cut out in this manner has the four vertical flat portions whose inner
peripheral surface 26a of the annular member 26 is substantially inscribed in the peripheral wall
12B of the metal case 12. By incorporating the upper unit 14 into the metal case 12, the
diaphragm subassembly 22 and the spacer 24 can be positioned at predetermined positions in
the metal case 12.
[0084]
At that time, the upper end portion of each vertical flat portion in the outer peripheral surface
26a of the annular member 26 is formed as a cut-out portion 26c cut in a substantially L-shaped
cross section along the circumferential direction, while the diaphragm subassembly Each of the
spacer 22 and the spacer 24 is formed to have an outer peripheral surface smaller than the
annular member 26, and the projections 22b and 24b are formed at positions corresponding to
the respective vertical flat portions in the respective outer peripheral surfaces 22a and 24a. The
upper unit 14 is formed in the metal case 12 because the front end surface of each of the
protrusions 22b and 24b is flush with the side surface 26c1 of each cut portion 26c. In the
assembled state, the outer peripheral surface 22a, 24a of each of the diaphragm subassembly 22
and the spacer 24 extends over the entire circumference of the metal case 12 It can be prevented
from interfering with the upper corner portion 12c.
[0085]
Therefore, it is possible to prevent in advance the occurrence of variations in the tension of the
vibrating film 28 due to the deformation of the vibrating film subassembly 22 and the spacer 24
due to the occurrence of such interference. It is possible to prevent in advance the occurrence of
variations in the sensitivity characteristics of
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[0086]
As described above, according to the present embodiment, in the condenser microphone 10
having the metal case 12, the diaphragm subassembly 22, the spacer 24 and the annular
member 26 are formed by cutting out as a plurality of upper units 14. Even in the case, it is
possible to prevent the occurrence of variations in sensitivity characteristics.
[0087]
In particular, in the present embodiment, since the projection 22b of the diaphragm subassembly
22 is disposed slightly away from the lower surface of the peripheral portion 12d of the upper
surface wall 12A of the metal case 12, Interference with the upper corner portion 12 c of the
metal case 12 can be prevented more reliably.
[0088]
On the other hand, in the method of manufacturing the condenser microphone 10 according to
the present embodiment, the diaphragm subassembly assembly 122, the spacer assembly 124,
and the annular member assembly 126 manufactured in advance are bonded to each other in a
state of being stacked from above Thus, an upper unit assembly 114 in which a plurality of
upper units 14 are connected to each other is manufactured, and then, with respect to the upper
unit assembly 114, a vibrating membrane subassembly is formed at the connection position
between the upper units 14. In a mode in which each beam portion 122a of the assembly 122
and each beam portion 124a of the spacer assembly 124 are cut, a recessed groove 114a having
a predetermined width is formed on the upper surface of each band plate portion 126a of the
annular member assembly 126. The plurality of upper units 14 are cut by cutting each band
plate portion 126a at the central portion of each recessed groove 114a. The projections 22b and
24b remain as the proximal end portions of the cut beam portions 122a and 124a on the outer
peripheral surfaces 22a and 24a of the diaphragm subassembly 22 and the spacer 24,
respectively, by a simple process. The front end face of the cutting member 26 can be formed
flush with the side face 26c1 of the cut portion 26c having a substantially L-shaped cross section
formed on the annular member 26.
[0089]
Then, by incorporating the upper unit 14 cut out in this manner in the metal case 12, it is
possible to obtain the condenser microphone 10 having no variation in sensitivity characteristics.
[0090]
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22
Further, in the present embodiment, when the upper unit 14 is assembled in the metal case 12,
the upper case 14 is dropped in the metal case 12 with the metal case 12 arranged upside down.
Because of this, the assembly process of the condenser microphone 10 can be simplified.
Also, even if the upper unit 14 is dropped into the metal case 12 in this manner, the upper unit
14 is incorporated straight with the annular member 26 substantially inscribed in the
circumferential wall 12 B of the metal case 12. The spacer 24 and the annular member 26 can be
arranged in a predetermined position in the metal case 12.
[0091]
In the above embodiment, in the step of cutting out the plurality of upper units 14 from the
upper unit assembly 114, when forming the recessed grooves 114a at the connection positions
between the upper units 14 of the upper unit assemblies 114, the respective recessed grooves
114a are formed. Are formed so that both side surfaces thereof are vertical.
This is due to the use of the rotary blade 102 whose both side surfaces are configured as parallel
surfaces, but instead of this, the rotary blade whose side surfaces are configured as V-shaped
tapered surfaces is used It is also possible to form each recessed groove 114a so that the both
side surfaces become an inclined surface by this.
Also in this case, the distal end surfaces of the protrusions 22b and 24b remaining as the base
end portions of the cut beam portions 122a and 124a on the outer peripheral surfaces 22a and
24a of the diaphragm subassembly 22 and the spacer 24, respectively. It can be formed by an
inclined surface flush with the side surface 26c1 of the cut-out portion 26c formed in the annular
member 26.
[0092]
In the above embodiment, the lower end portion of the side surface 26c1 of the cut-out portion
26c having a substantially L-shaped cross section formed in the annular member 26 is somewhat
rounded. It is due to the fact that the club has some roundness.
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The cross-sectional shape of the cut-out portion 26c has no influence on the interference
between the outer peripheral surfaces 22a and 24a of the vibrating film subassembly 22 and the
spacer 24 and the upper corner portion 12c of the metal case 12, so The roundness generated at
the lower end portion of the side surface 26c1 of the portion 26c may be larger, conversely
smaller, or may be a non-rounding pin angle.
The same applies to the case where the side surface 26c1 of the cut-out portion 26c is formed to
be an inclined surface.
[0093]
Although the case where the condenser microphone 10 is an electret condenser microphone has
been described in the above embodiment, the same operation as that of the above embodiment is
performed in the case where the condenser microphone 10 is a condenser microphone
configured to be applied with a charge voltage. You can get the effect.
[0094]
The numerical values shown as specifications in the above embodiment are merely examples, and
of course these may be set to different values as appropriate.
[0095]
DESCRIPTION OF REFERENCE NUMERALS 10 condenser microphone 12 metal case 12A upper
surface wall 12B circumferential wall 12a sound hole 12b extension piece 12c upper corner
portion 12d peripheral portion 14 upper unit 16 rear electrode plate 16A electrode plate main
body 16B electret layer 16a through hole 18 contact spring 18A central longitudinal direction
18B Longitudinal Ends 18a, 18b Spherical convex portion 20 Lower unit 22 Vibrating film
subassembly 22a, 24a, 26a Outer peripheral surface 22b, 24b Projection 24 Spacer 26 Annular
member 26b, 36b Inner peripheral surface 26c Cutout portion 26c1 Side surface 28 Vibration
Membrane 30 support ring 32 circuit board 32a first conductive layer 34 impedance conversion
element 34a input terminal 36 annular substrate 36c second conductive layer 102, 104 rotary
blade 114 upper unit aggregate 114a concave Groove 114b Through hole 122 Vibrating film
subassembly assembly 122a, 124a Beam 124 spacer assembly 126 Annular member assembly
126a Band plate C Capacitor structure
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