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JP2017112505

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This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
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DESCRIPTION JP2017112505
Abstract: The present invention provides a speaker diaphragm that can reduce the disturbance of
the sound pressure frequency characteristics in the high frequency range including the ultra high
frequency range and reduce the manufacturing cost, a speaker provided with the same, and a
method of manufacturing the speaker diaphragm. A diaphragm (30) is vibratably supported by a
speaker main body via an edge (14), and a dome portion (32) bulged in the Z-axis direction and
an outer peripheral edge of the dome portion (32) And an annular cone portion 34 extending in a
direction. The dome portion 32 and the cone portion 34 are integrally formed of magnesium or
magnesium alloy seamlessly, and the outer peripheral end of the cone portion 34 extends to
substantially the same height P as the maximum projecting position of the dome portion 32. An
annular step portion 36 for attaching a tubular voice coil bobbin is provided along the boundary
between the dome portion 32 and the cone portion 34. [Selected figure] Figure 3
Speaker diaphragm, speaker provided with the same, and method of manufacturing the speaker
diaphragm
[0001]
The present invention relates to a diaphragm used for a speaker, and more particularly to a
balance dome type diaphragm in which a cone portion is formed around a dome portion, a
speaker provided with the same, and a method of manufacturing a speaker diaphragm.
[0002]
In recent years, with the spread of high resolution audio, development of a speaker capable of
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reducing the disturbance of the sound pressure frequency characteristic in the high range
including the super high range of 20 kHz or more has been promoted.
In general, a metal-based diaphragm is suitable for high-range reproduction because it is high in
rigidity and high in high-range limit frequency as compared with a resin-based diaphragm.
Among them, magnesium or a magnesium alloy is a metal material most suitable for high
frequency range reproduction because it has a small specific gravity and a small decrease in
sound pressure as compared with aluminum or titanium.
[0003]
For example, Patent Document 1 describes a dome-shaped diaphragm in which a thin magnesium
sheet is formed by rolling a magnesium base material a plurality of times by changing a rolling
amount, and a dome portion and an edge are integrally formed from the magnesium sheet. It is
done.
[0004]
Patent No. 4152804
[0005]
However, the crystal structure of magnesium is a close-packed hexagonal crystal structure, has
strong plastic anisotropy, and is difficult to stretch.
Therefore, it is difficult to plastically process magnesium or a magnesium alloy, so even though it
can be processed into a simple shape like the dome-shaped diaphragm described in the abovementioned Patent Document 1, a cone portion is formed around the dome portion. It was difficult
to bend and process the magnesium sheet into a complex shape such as a balance dome shape
that is formed and suitable for high frequency range output.
Therefore, conventionally, the dome portion and the cone portion are separately formed from a
sheet material of magnesium or a magnesium alloy, and joined by an adhesive or the like to form
a balance dome type diaphragm. In this case, a joint is formed along the boundary between the
dome portion and the cone portion of the diaphragm, and the weight load of the adhesive lowers
the sound pressure level, which tends to disturb the sound pressure frequency characteristics. In
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addition, since the dome portion and the cone portion of the diaphragm for a speaker are joined
with an adhesive, there is a problem that the number of operation steps is increased and the
manufacturing cost is increased.
[0006]
An object of the present invention is to provide a speaker diaphragm which can reduce the
manufacturing cost while reducing the disturbance of the sound pressure frequency
characteristic in the high frequency range including the superhigh frequency range, the speaker
provided with the same, and the method of manufacturing the speaker diaphragm. It is to
provide.
[0007]
A diaphragm for a speaker according to an aspect of the present invention is a diaphragm for a
speaker that is supported by a speaker main body so as to be able to vibrate via an edge, and a
dome portion formed to protrude from a central portion of the diaphragm; And an annular cone
extending in a direction inclined with respect to the projecting direction of the dome from the
outer peripheral edge of the portion; and the dome and the cone are seamlessly and integrally
formed of a sheet material made of magnesium or a magnesium alloy And the annular step for
attaching the cylindrical voice coil bobbin along the boundary between the dome portion and the
cone portion by extending the outer peripheral end of the cone portion to at least substantially
the same height position as the maximum projecting position of the dome portion Is provided.
Here, "seamlessly" means that the dome portion and the cone portion do not include those joined
by, for example, an adhesive or the like. In addition, “approximately the same height position”
refers to the case where the position of the outer peripheral end of the cone portion is the
maximum projection of the dome portion, in addition to the case where the maximum protruding
position of the dome portion is the same height position It is meant to include cases slightly
lower than the position.
[0008]
In the speaker diaphragm according to the present invention, the annular step portion is a
contact surface extending in a direction orthogonal to the projecting direction of the dome
portion and coming into contact with the axial direction end face of the voice coil bobbin It may
be formed by a guide surface extending in the direction opposite to the projecting direction and
along the side surface of the voice coil bobbin.
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[0009]
Further, in the speaker diaphragm according to the present invention, the annular stepped
portion has a width of the contact surface in a direction orthogonal to the projecting direction of
the dome portion as a, and a height of the guide surface in the projecting direction of the dome
portion is b. It may be formed to satisfy the relation of 0.28a <b <2.5a.
[0010]
Further, the speaker diaphragm according to the present invention may have an edge for
vibratably supporting the outer peripheral end of the cone of the speaker diaphragm, and a voice
coil attached to the step of the speaker diaphragm. Good.
[0011]
A speaker according to another aspect of the present invention has a speaker diaphragm
according to any one of the above configurations, a frame supporting the speaker diaphragm in a
freely vibrating manner through an edge, and a magnetic gap into which a voice coil is inserted.
And a magnetic circuit.
[0012]
A method of manufacturing a speaker diaphragm according to another embodiment of the
present invention is a method of manufacturing a speaker diaphragm manufactured using a
sheet material made of magnesium or magnesium alloy and having a cone portion along the
outer peripheral edge of the dome portion. And a dome preform forming step of forming a dome
portion preforming portion by extruding a magnesium or magnesium alloy sheet material a
plurality of times at a predetermined protrusion height by pressing, and a sheet material located
on the outer periphery of the dome portion preforming portion The cone preform forming step
of forming the annular cone portion preforming portion by bending the portion of the portion in
the direction inclined with respect to the projecting direction of the dome portion preforming
portion by a predetermined bending amount multiple times by press processing; The preform
portion is shaped into a dome portion, and at least the outer peripheral end of the cone portion
preform portion is formed. Shaping into a cone extending to a height position substantially the
same as the maximum projecting position of the frame, and forming an annular step attaching
the voice coil bobbin along the boundary between the dome and the cone; Is provided.
[0013]
In the method for manufacturing a speaker diaphragm according to the present invention, the
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predetermined protrusion height is set to be smaller than the maximum protrusion height of the
dome portion of the speaker diaphragm, and the predetermined bending amount is the speaker
diaphragm It may set so that it may become smaller than the projection height of the perimeter
end in the cone part of.
[0014]
According to the speaker diaphragm of one aspect of the present invention, the dome portion
and the cone portion of the speaker diaphragm made of a sheet material of magnesium or
magnesium alloy are seamlessly and integrally formed, and therefore, they include an ultra high
range. It is possible to reduce the disturbance of the sound pressure frequency characteristics in
the high range.
Furthermore, since the bonding operation of bonding the dome portion and the cone portion of
the speaker diaphragm with adhesive is unnecessary, the number of operation steps can be
reduced, and the manufacturing cost can be reduced.
[0015]
According to the speaker which is another aspect of the present invention, since the dome
portion and the cone portion of the speaker diaphragm made of magnesium or magnesium alloy
sheet material are integrally formed seamlessly, it is possible to use a high frequency range
including an ultra high frequency range. The disturbance of the sound pressure frequency
characteristics can be reduced, and the manufacturing cost can be reduced because it is not
necessary to bond the dome portion and the cone portion with an adhesive.
[0016]
According to the method of manufacturing a diaphragm for a speaker which is another aspect of
the present invention, the dome material preform and the cone material preform are formed after
the sheet material made of magnesium or magnesium alloy is protruded stepwise to form the
dome material. And can be shaped into a cone.
Therefore, it is possible to form the speaker diaphragm in which the cone portion is formed along
the dome portion and the outer peripheral edge while suppressing the generation of wrinkles
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and cuts in the sheet material.
As a result, it is possible to manufacture a speaker diaphragm capable of reducing the
disturbance of the sound pressure frequency characteristics in the high range including the ultra
high range.
[0017]
It is a perspective view showing a speaker containing a diaphragm for speakers which is one
embodiment of the present invention.
FIG. 2 is a cross-sectional view taken along the line AA shown in FIG.
FIG. 3 (a) is a plan view of the speaker diaphragm, and FIG. 3 (b) is a cross-sectional view taken
along the line CC in FIG. 3 (a).
4 (a) is a partial enlarged view of the region B shown in FIG. 2, and FIG. 4 (b) is a view showing a
state when the voice coil bobbin is attached to the stepped portion of the diaphragm.
It is a graph which shows the sound pressure frequency characteristic by the finite element
method of (a) diaphragm of one embodiment of the present invention, (b) diaphragm of
comparative example 1, and diaphragm of (c) comparative example 2. FIG. 6A shows a
diaphragm according to a first modification, and FIG. 6B shows a diaphragm according to a
second modification. It is a graph which shows the sound pressure frequency characteristic by
the finite element method of (a) diaphragm of one Embodiment of this invention, the diaphragm
of (b) modification 1, and the diaphragm of (c) modification 2. FIG. It is a figure which shows the
1st process and 2nd process among the manufacturing methods of the diaphragm for speakers
which is one Embodiment of this invention. FIG. 9 is a view showing third to fifth steps in the
method for producing the speaker diaphragm, as in FIG. 8.
[0018]
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Hereinafter, an embodiment according to the present invention will be described in detail with
reference to the attached drawings. In the description, specific shapes, materials, numerical
values, directions and the like are exemplifications for facilitating the understanding of the
present invention, and can be appropriately changed in accordance with applications, purposes,
specifications and the like. In addition, in the case where a plurality of embodiments, modified
examples, and the like are included below, it is assumed from the beginning that these
characteristic portions are appropriately combined and used.
[0019]
FIG. 1 is a perspective view of a speaker 10 including a speaker diaphragm 30 according to an
embodiment of the present invention. FIG. 2 is a cross-sectional view taken along line AA in FIG.
In FIGS. 1 and 2, the vibration direction of the diaphragm 30 is taken as the Z-axis direction
(projecting direction), and a plane perpendicular to this is shown as an XY plane. In FIG. 2, the
axial center of the speaker 10 is shown as CL. As shown in FIG. 1 and FIG. 2, the speaker 10 is,
for example, an electrodynamic speaker assembled into a headphone, and is a substantially disklike electroacoustic transducer. The speaker 10 includes a speaker body 11 including a frame 12
that forms an outer shape. As the frame 12, one obtained by forming a material having an
appropriate strength into a predetermined shape can be used. For example, a resin molded
product can be used for the frame 12. In addition, the speaker 10 includes, in the internal space
of the frame 12, components of the vibration system such as the diaphragm 30, the edge 14, and
the voice coil 16, and a magnetic circuit 20.
[0020]
First, components other than the diaphragm 30 will be described. As shown in FIG. 1, the edge
14 has an arc-shaped roll portion 14a disposed along the outer peripheral end of the diaphragm
30, and a flange portion 14b connected to the outer peripheral edge of the roll portion 14a. The
inner peripheral end of the roll portion 14 a of the edge 14 is fixed to the outer peripheral end of
the diaphragm 30 by fixing means such as bonding, for example, and supports the diaphragm 30
in a freely vibrating manner. In addition, grooves F are provided in the roll portion 14a at equal
pitches. On the other hand, the flange portion 14 b of the edge 14 is fixed to an annular ring 12
a attached to the frame 12 by fixing means such as bonding. As the edge 14, a thermoplastic
elastomer resin can be used, and one molded into a predetermined shape having flexibility can be
used. As thermoplastic elastomer resin, polyurethane type, polyolefin type, polyamide type,
polyethylene type, polystyrene type can be used. In addition, as a material of the edge 14, rubber,
foamed rubber, a coated cloth or the like may be used.
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[0021]
As shown in FIG. 2, the voice coil 16 is composed of a voice coil bobbin 17 and a coil 18 wound
around it. The voice coil bobbin 17 is a thin insulator cylindrical member formed in a
substantially annular shape. As a thin insulator, a resin film or the like having appropriate
strength and heat resistance can be used. Each coil 18 is formed by winding a wire with
insulation coating along the outer circumferential surface of the voice coil bobbin 17 with a
predetermined number of turns. As a conductor wire with an insulation coating, what coat |
covered with the insulation varnish the copper wire with a circular cross section can be used. The
upper end in the axial direction of the voice coil 16 is fixed to a diaphragm 30 described later.
[0022]
As shown in FIG. 2, the magnetic circuit 20 includes a substantially annular magnet 22, a top
plate 24, and a yoke 26. The magnet 22 is disposed so that the upper and lower ends thereof are
sandwiched by the top plate 24 and the cylindrical yoke 26 with a bottom in a stacked state in
the cylindrical portion 12 b provided at the axial end of the frame 12. As a material of the
magnet 22, a ferrite magnet, or an alnico based magnet made of an alloy of aluminum, nickel, or
cobalt, a rare earth magnet including neodymium, or the like can be used. The yoke 26 has an
outer peripheral portion 26 a extending upward to a position facing the outer peripheral surface
of the top plate 24 with the coil 18 wound around the voice coil bobbin 17 interposed
therebetween, and a magnetic gap SP is formed between the yoke 26 and the top plate 24. It is
formed. The voice coil 16 described above is inserted in the magnetic gap SP. The top plate 24 is
formed in a substantially annular shape having the same inner diameter as the magnet 22. On
the other hand, a through hole H having a size that matches the inner diameter of the
substantially annular magnet 22 is also provided in the bottom portion 26 b of the yoke 26. For
this reason, the internal space of the voice coil bobbin 17 is communicated with the outside, so
that the heat dissipation can be enhanced and the output characteristic of the bass can be
adjusted.
[0023]
Subsequently, the configuration of the diaphragm 30 will be described with reference to FIG. 3
(a) is a plan view of the diaphragm 30, and FIG. 3 (b) is a cross-sectional view taken along the line
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CC in FIG. 3 (a).
[0024]
As shown in FIG. 3A, the balance dome-type diaphragm 30 is inclined in the Z-axis direction from
the outer peripheral edge of the dome portion 32 protruding in the Z-axis direction at the central
portion and the outer periphery of the dome portion 32. It is a balance dome-type diaphragm
having an annular cone portion 34 extending in the above-mentioned direction. Preferably, the
stepped portion 36 is provided along the boundary between the dome portion 32 and the cone
portion 34 of the diaphragm 30. The dome portion 32 may be formed in a planar shape with a
constant curvature, may be configured by a curved surface of a plurality of different curvatures,
or may be formed in a spindle shape. The annular cone portion 34 may be formed by a curved
surface such as a circumferential side of a truncated cone, or may be formed by a curved surface
bulging in the same direction as the dome portion 32 or a curved surface recessed in the
opposite direction. It is also good.
[0025]
As shown in FIG. 3 (b), the cone portion 34 of the diaphragm 30 extends to a position
substantially the same height as the maximum projecting position of the dome portion 32 of the
diaphragm 30. Therefore, the height P of the maximum projecting position of the dome portion
32 and the height Q of the outer peripheral end of the cone portion 34 are formed to be
substantially the same height. Here, “approximately the same height” refers to the case where
the height P of the maximum protruding position of the dome portion 32 described above and
the height Q of the outer peripheral end of the cone portion 34 are the same height, and the
outer peripheral end This means that the case where the height Q is slightly lower than the
height P of the dome portion 32 of the dome portion 32 described above is included. Further, the
height Q of the outer peripheral end of the cone portion 34 in the diaphragm 30 may be set
higher than the height P of the maximum projecting position of the dome portion 32.
[0026]
The dome portion 32 and the cone portion 34 of the diaphragm 30 are formed by bending a
sheet material made of magnesium or a magnesium alloy by press processing to be described
later. For this reason, the dome portion 32 and the cone portion 34 are integrally configured
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seamlessly. "Seamlessly" in the present embodiment means, for example, that it does not include
those bonded by an adhesive or the like.
[0027]
Next, the configuration of the stepped portion 36 of the diaphragm 30 will be described with
reference to FIG. FIG. 4A is a partial enlarged view of the region B shown in FIG. 2, and FIG. 4B is
a view showing how the voice coil bobbin 17 is attached to the step portion 36 of the diaphragm
30. As shown in FIG. 4A, the stepped portion 36 of the diaphragm 30 has a contact surface 36a
substantially parallel to the XY plane and a guide surface 36b substantially parallel to the Z-axis
direction. . The contact surface 36 a of the step portion 36 is a surface to which an upper end
which is an axial end surface of the voice coil bobbin 17 abuts and is fixed. The guide surface 36
b is provided on the inner diameter side relative to the contact surface 36 a so as to approach
and face the inner peripheral surface of the voice coil bobbin 17.
[0028]
As shown in FIG. 4B, when the voice coil bobbin 17 is attached to the diaphragm 30, the adhesive
BN, such as an epoxy resin, is used as a step of the diaphragm 30 with the diaphragm 30 placed
on the lower side. It is applied to the portion 36 and adhesively fixed in a state in which the
upper end of the voice coil bobbin 17 is in contact with the contact surface 36 a while being
along the guide surface 36 b of the stepped portion 36. By bringing the upper end of the voice
coil bobbin 17 into contact with the contact surface 36a as described above, it is possible to
prevent the bonding position of the voice coil bobbin 17 from being displaced. For this reason, it
is possible to prevent the occurrence of variations in the sound pressure frequency
characteristics of the diaphragm 30 due to the displacement of the bonding position of the voice
coil bobbin 17. Further, by providing the stepped portion 36 on the diaphragm 30, the adhesive
BN can be easily applied, and the workability in the bonding operation can be improved.
[0029]
Further, as shown in FIG. 4A, when the width in the X direction of the contact surface 36a is a
and the width in the Z axis direction of the guide surface 36b is b, the relationship of the
following equation (1) is It is preferable to set to satisfy.
[0030]
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0.28a<b<2.5a・・・・(1)
[0031]
In this embodiment, as an example, a is 0.25 mm and b is 0.25 mm.
The width a of the contact surface 36a of the step portion 36 of the diaphragm 30 is 1 mm, the
height b of the guide surface 36b is 0.28 mm (b = 0.28 a), and the other configuration is the
same as that of the diaphragm 30. The vibrating plate of Comparative Example 1 is used.
Similarly, a configuration in which the width a of the contact surface is 0.25 mm and the height b
of the guide surface is 0.625 mm (b = 2.5 a) is used as the diaphragm of Comparative Example 2.
[0032]
FIG. 5 is a simulation of sound pressure frequency characteristics by the finite element method
for (a) the diaphragm 30 of this embodiment, (b) the diaphragm of Comparative Example 1, and
(c) the diaphragm of Comparative Example 2. It is a graph which shows the result of having
carried out.
[0033]
As shown in FIG. 5, the diaphragm 30 of this embodiment has less peaks and dips than the
diaphragms of Comparative Examples 1 and 2 in the high frequency range of 10 kHz or more,
and the disturbance of the sound pressure frequency characteristic is reduced. I understand.
On the other hand, in the diaphragm of Comparative Example 1, since the width a of the contact
surface 36a is longer than the guide surface 36b of the stepped portion 36, the adhesive BN is
thinly spread on the contact surface 36a. For this reason, the adhesion between the voice coil
bobbin 17 and the step portion 36 is weak, and the adhesion strength between the voice coil
bobbin 17 and the step portion 36 is insufficient, so that peaks and dips easily occur in a high
sound range. In the diaphragm of Comparative Example 2, since the height b of the guide surface
36b is too long with respect to the width a of the contact surface 36a of the stepped portion 36,
the adhesive strength between the guide surface 36b and the voice coil bobbin 17 is too strong.
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In the high frequency range, the vibration of the diaphragm is likely to be disturbed, the peak
and dip become large, and the disturbance of the sound pressure frequency characteristic
becomes large. On the other hand, according to the diaphragm 30 of this embodiment, the
adhesive BN can adhere to the contact surface 36a in a state of having a sufficient thickness, and
the upper end of the voice coil bobbin 17 in the adhesive BN. Sufficient adhesive strength can be
obtained by inserting and solidifying. Further, since the length of the guide surface 36 b is
appropriate, the adhesive strength with the voice coil bobbin 17 does not become too strong, and
the disturbance of the sound pressure frequency characteristic in the high sound range can be
suppressed.
[0034]
Then, the modification examples 1 and 2 of the step part 36 in the diaphragm 30 are
demonstrated using FIG. 6 (a) and FIG.6 (b). FIG. 6A is a partial enlarged view showing the step
44 of the diaphragm 42 which is the first modification, and FIG. 6B is a partial enlarged view
showing the step 46 of the diaphragm 45 which is the second modification. is there.
[0035]
The diaphragms 42 and 45 differ from the diaphragm 30 only in the configuration of the step
portions 44 and 46, and therefore, in the following description, only the configuration of the step
portions 44 and 46 of the diaphragms 42 and 45 will be described.
[0036]
As shown in FIG. 6A, the stepped portion 44 of the diaphragm 42 has an abutment surface 44a
that abuts on the upper end surface of the voice coil bobbin 17 and a guide surface 44b provided
outside the abutment surface 44a. doing.
The contact surface 44a is formed substantially parallel to the XY plane. The guide surface 44 b
is formed substantially in parallel to the Z-axis direction, and is disposed so as to face the outer
peripheral surface of the voice coil bobbin 17 in close proximity.
[0037]
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As shown in FIG. 6B, the step 46 of the diaphragm 45 is in contact with the contact surface 46a
substantially parallel to the XY plane contacting the upper end surface of the voice coil bobbin
17 and both ends of the contact surface 46a. Guide surfaces 46b and 46c which are continuous
substantially orthogonal to the contact surface 46a are provided. According to this configuration,
since the upper end of the voice coil bobbin 17 is sandwiched between the two guide surfaces 46
b and 46 c, the voice coil bobbin 17 becomes more difficult to shift from the bonding position.
[0038]
7A shows the diaphragm 30 of the above embodiment, FIG. 7B shows the diaphragm 42 of the
first modification, and FIG. 7C shows the diaphragm 45 of the second modification. It is a graph
which shows the result of having performed simulation.
[0039]
As shown in FIG. 7, in the diaphragms 42 and 45 as well as the diaphragm 30 in the above
embodiment, it is understood that the disturbance of the sound pressure frequency characteristic
can be reduced with less peaks and dips even in the high frequency range of 10 kHz or more.
[0040]
According to the speaker 10 relating to the present embodiment, the dome portion 32 and the
cone portion 34 of the speaker diaphragm 30 are integrally formed of a sheet material made of
magnesium or a magnesium alloy without seams. It is also possible to reduce the disturbance of
the sound pressure frequency characteristics of the high range including the range.
Further, even in the balance dome type speaker diaphragm, since it is not necessary to bond the
dome portion 32 and the cone portion 34 with an adhesive, it is not necessary to bond the dome
portion 32 and the cone portion 34. The manufacturing cost can also be reduced.
[0041]
Then, the manufacturing method of the diaphragm 30 mentioned above is demonstrated using
FIG. 8 and FIG.
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The crystal structure of magnesium metal is a close-packed hexagonal crystal structure, and its
plastic anisotropy is strong compared to other metals such as aluminum, so it is difficult to
stretch, and it is difficult to apply plastic working. Accordingly, the dome portion and the cone
portion are seamlessly and integrally formed of a sheet material made of magnesium or a
magnesium alloy, and the outer peripheral end of the cone portion extends at least to
substantially the same height position as the maximum projecting position of the dome portion. It
is very difficult to form such a balance dome type speaker diaphragm. However, it can be realized
by the following manufacturing method. FIG. 8 is a diagram showing a first step and a second
step in the method of manufacturing the diaphragm 30 in the present embodiment. FIG. 9 is a
diagram showing a third step to a fifth step in the method of manufacturing the diaphragm 30,
following FIG. In FIG. 8 and FIG. 9, the cross-sectional shape which passes along the axial center
CL of the sheet material BL pinched by the 1st metal mold | die and the 2nd metal mold | die in
each process is shown.
[0042]
As shown in FIG. 8, first, a sheet material BL made of magnesium or a magnesium alloy is
prepared. The thickness of the sheet material BL is 45 μm in the present embodiment, but may
be 1 mm or less. Further, as the sheet material BL, for example, a magnesium alloy AZ31 or the
like may be used.
[0043]
In the first step (dome preforming step), as shown in FIG. 8, the first mold 51 has a bulging
portion 51a whose center portion has a dome shape or a conical shape, and a recess 52a
corresponding thereto. The sheet material BL is sandwiched by the second mold 52, and the
central portion of the sheet material BL is protruded in the Z-axis direction at a predetermined
protruding height α to form a dome portion preforming portion 62. Under the present
circumstances, the 1st metal mold | die 51 and the 2nd metal mold | die 52 are beforehand
heated by 200 degreeC-240 degreeC. Thereby, the sheet material BL is likely to be plastically
deformed. Also in each of the following steps, each mold is assumed to be heated as well.
[0044]
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The protruding height α of the sheet material BL by the first mold 51 and the second mold 52 in
the first step corresponds to the height P of the maximum protruding position of the dome
portion 32 of the diaphragm 30 (see FIG. 3B). On the other hand, it may be set to satisfy formulas
(2) to (4) shown below. Here, "t" is the thickness of the sheet material BL. 0.4 P ≦ α <P (100
μm ≦ t ≦ 1 mm) (2) 0.5 P ≦ α ≦ 0.95 P (50 μm ≦ t <100 μm) (3) 0.6 P ≦ α ≦ 0.9 P (t
<50 μm) (4) By setting the protrusion height α according to the above equations (2) to (4), the
sheet material BL is little by little Since plastic deformation can be performed, the generation of
wrinkles and cuts of the sheet material BL can be suppressed.
[0045]
In the second step (dome preforming step), as in the first step, the sheet material BL is
sandwiched by the first mold 53 having the bulging portion 53a and the second mold 54 having
the recess 54a corresponding thereto. Then, the dome portion preforming portion 62 of the
sheet material BL is protruded in the Z-axis direction at a predetermined protruding height β.
The protrusion height β may be set in accordance with the above-described equations (2) to (4),
similarly to the protrusion height α in the first step. Further, the protrusion height β in the
second step may be set larger than the protrusion height α in the first step. As a result, since the
dome portion preforming portion 62 can be processed in stages, wrinkles and cuts are less likely
to occur in the sheet material BL.
[0046]
Further, the number of times of pressing in the second step is not limited to one, and pressing
may be performed multiple times. When pressing is performed a plurality of times in the second
step, the protrusion height β may be changed each time. The protruding height β may be the
same as the protruding height α in the first step.
[0047]
In the third step (corn preforming step), as shown in FIG. 9A, the cone-shaped portion 55b is
formed in a substantially annular shape along the outer peripheral edge of the dome-shaped
bulging portion 55a and the bulging portion 55a. The sheet material BL is sandwiched between
the first mold 55 and the second mold 56 having the recess 56a corresponding to the bulging
portion 55a and the cone-shaped portion 56b corresponding to the cone-shaped portion 55b.
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The bulging portion 55 a of the first mold 55 may have the same shape as the bulging portion 53
a of the first mold 53 in the second step. In this manner, the portion of the sheet material BL on
the outer periphery of the dome portion preforming portion 62 is bent in the same direction as
the bulging direction of the dome portion preforming portion 62 by a predetermined bending
amount γ Form. The predetermined bending amount γ is expressed by the following equation
(5) with respect to the height Q (see FIG. 3 (b)) of the outer peripheral end of the cone portion 34
of the diaphragm 30, similarly to the protrusion height α in the first step. ) (7) may be set. 0.4Q
≦ γ <Q (100 μm ≦ t ≦ 1 mm) (5) 0.5 Q ≦ γ ≦ 0.95 Q (50 μm ≦ t <100 μm) (6) 0.6 Q ≦
γ ≦ 0.9 Q (t <50 μm) (7)
[0048]
In the fourth step (corn preforming step), as in the third step, the first mold 57 having the
bulging portion 57a and the cone-shaped portion 57b, and the corresponding recess 58a and the
cone-shaped portion 58b The sheet material BL is sandwiched by the second mold 58. In this
manner, the cone preformed portion 64 of the sheet material BL is further bent in the Z-axis
direction by a predetermined bending amount ζ. The predetermined bending amount ζ may be
set in the same manner as the predetermined bending amount γ in the third step. Thereby, the
cone part preforming part 64 of sheet material BL can be bend | folded in steps, and can be
processed. Further, as in the second step described above, the predetermined bending amount ζ
in the fourth step may be set larger than the predetermined bending amount γ in the third step.
Furthermore, the number of times of press processing in the fourth step is not limited to one, and
the cone portion preformed portion 64 of the sheet material BL may be pressed and bent a
plurality of times.
[0049]
In the fifth step (shaping step), as shown in FIG. 9, a cone-shaped portion having substantially the
same cross-sectional shape as bulging portion 59a and cone portion 34 having substantially the
same cross-sectional shape as dome portion 32 of diaphragm 30. The sheet material BL is
sandwiched and pressed by a first mold 59 having a 59b and a second mold 61 having a recess
61a corresponding to the bulging portion 59a and a cone-shaped portion 61b corresponding to
the cone-shaped portion 59b . Further, a stepped portion 59 c having the same cross-sectional
shape as the annular stepped portion 36 of the diaphragm 30 may be provided at the boundary
between the bulging portion 59 a of the first mold 59 and the cone-shaped portion 59 b. Then, a
stepped portion mold portion 61c corresponding to the stepped portion mold portion 59c may
be provided at the boundary between the concave portion 61a and the cone portion 61b of the
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second mold 61. In this case, the stepped portion 36 can be formed along the boundary between
the dome portion 32 and the cone portion 34 of the diaphragm 30.
[0050]
Thus, the dome portion 32 and the cone portion 34 of the diaphragm 30 can be formed from the
dome portion preforming portion 62 and the cone portion preforming portion 64 of the sheet
material BL, respectively. Thereafter, unnecessary portions around the cone portion 34 in the
sheet material BL are removed to complete the diaphragm 30.
[0051]
According to the method of manufacturing the speaker diaphragm 30 of the above embodiment,
the dome material pre-forming portion 62 and the cone portion pre-forming portion 64 are
formed by projecting the sheet material BL made of magnesium or magnesium alloy in a stepwise
manner. The portion 32 and the cone portion 34 can be shaped. For this reason, the dome
portion 32 and the outer peripheral end of the cone portion 34 extend at least to substantially
the same height position as the maximum protruding position of the dome portion 32, while
suppressing the formation of wrinkles and cuts in the sheet material BL The cone portion 34 can
be shaped. Therefore, it is possible to form the speaker diaphragm in which the cone portion 34
is formed along the dome portion 32 and the outer peripheral edge thereof while suppressing
the generation of wrinkles or cuts in the sheet material BL. As a result, it is possible to
manufacture a balance dome type speaker diaphragm 30 capable of reducing the disturbance of
the sound pressure frequency characteristic in the high frequency range including the super high
frequency range.
[0052]
The present invention is not limited to the above-described embodiment and the modifications
thereof, and various improvements and modifications can be made within the scope of the
matters described in the claims of the present application and the equivalents thereof.
[0053]
Reference Signs List 10 speaker 11 speaker body 12 frame 14 edge 16 voice coil 17 voice coil
bobbin 18 coil 20 magnetic circuit 22 magnet 24 top plate 26 yoke 30, 42, 45 (for speaker)
diaphragm, 32 dome portion, 34 cone portion, 36, 42, 45 step portion, 36a, 44a, 46a contact
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surface, 36b, 44b, 46b guide surface, 51, 53, 55, 57, 59 first mold, 52, 54 , 56, 58, 61 second
mold, a width of abutment surface, height of guide surface b, height of maximum projecting
position, height of peripheral end of Q cone portion, height of α, β protruding, γ, 折 り 曲 げ
bending amount, BL sheet material.
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