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JPH08340593

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DESCRIPTION JPH08340593
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
speaker diaphragm having a shape such as a cone and a dome, and more particularly to material
improvement of a speaker diaphragm using non-woven cloth, and further relates to a
manufacturing method thereof. is there.
[0002]
2. Description of the Related Art For diaphragm materials in loudspeakers, the reason is that the
materials are inexpensive and the characteristics required for the diaphragm such as density,
Young's modulus, internal loss, etc. are relatively well-balanced. Papermaking of wood pulp is
most frequently used.
[0003]
However, such diaphragms using wood pulp have many steps such as beating and forming of
pulp and there is a disadvantage that the production is complicated, so as a solution to this, fibers
are the same as pulp. In the related art, a diaphragm using a non-woven fabric made of a
synthetic resin fiber is proposed which can obtain uniform piston vibration without directionality
and which is easy to form the diaphragm.
[0004]
A diaphragm made of a conventionally proposed non-woven fabric is formed by impregnating a
non-woven fabric composed of single or plural different synthetic resin fibers with a
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thermosetting resin such as phenol resin or a rubber-based resin such as nitrile rubber ( JP-A 50123330), a non-woven fabric composed of two types of synthetic resins having different melting
points, which is formed by heating and pressing at a melting point temperature in a low-meltingpoint synthetic resin (JP-A-59-176995), fiber diameter 0.02 to One obtained by heat and
pressure molding a non-woven fabric made of 0.5 denier polyolefin fiber (Japanese Patent
Publication No. 57-52759) and the like.
[0005]
In the conventional speaker diaphragm of such a configuration, the shape of the diaphragm is
formed by impregnating a non-woven fabric made of synthetic resin fiber with a thermosetting
resin or a rubber-based resin. A complicated process of impregnating the thermosetting resin or
the rubber-based resin is necessary to keep the
Furthermore, since it takes a long time to cure the thermosetting resin or crosslink the rubberbased resin, there is a disadvantage that the vibration plate forming time becomes long and the
workability is poor.
[0006]
Then, in a non-woven fabric made of two types of synthetic resins having different melting
points, which is formed by heating and pressing at a melting point temperature of a low melting
point synthetic resin, the low melting point synthetic resin fiber is melted and made to flow. The
diaphragm shape is formed by acting as a binder resin for the synthetic resin fiber of the melting
point.
However, in this diaphragm, since the low melting point resin is melted, the molten synthetic
resin is fused to the mold, and even if it is cooled, it may not be easily released. Molded molded
articles may be deformed.
In addition, in the molding process, in order to solidify the molten synthetic resin and to avoid
deformation at the time of mold release, a long cooling time on the mold of the molded article is
required, and after molding, new molding is performed with the same mold. In order to form the
diaphragm, the mold must be heated again to the low melting point temperature, and the yield at
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the time of formation is poor, and there is also a disadvantage that it is not suitable at all for
mass production.
[0007]
Further, in a non-woven fabric made of polyolefin fibers having a fiber diameter of 0.02 to 0.5
denier that has been heat-pressed and molded, it is shrunk because it is constituted by single
fibers after heat-pressure molding and demolding And molded articles may be deformed.
Furthermore, this diaphragm adds a diaphragm shape by fusing polyolefin ultrafine fibers, but in
this case, the fiber is fused to a mold, and as in the above, it takes a long time Cooling time is
required.
[0008]
Therefore, the present invention solves the disadvantages of the prior art and melts a synthetic
resin fiber having the lowest melting temperature among the synthetic resin fibers, a nonwoven
fabric consisting of two or more types of synthetic resin long fibers having different melting
temperatures. By heat-pressing near the temperature to fuse the intersection points of the
entangled long fibers, no resin for impregnation is required to form the diaphragm shape, mold
release is easy, and deformation such as contraction occurs. An object of the present invention is
to provide a speaker diaphragm that does not occur, and further, to provide a method of
manufacturing the speaker diaphragm that is easy to mold and can be molded in a short time and
is excellent in mass productivity.
[0009]
[Means for Solving the Problems] The speaker diaphragm according to the present invention for
achieving the above object is a non-woven fabric composed of long fibers of two or more types of
synthetic resin fibers having different melting temperatures. A speaker diaphragm formed by
heating and pressing near the melting temperature of the synthetic resin fiber having the lowest
melting temperature among the long fibers by fusing the intersection points of the entangled
long fibers Is a composite long fiber having a substantially circular cross-section, which is
constructed by combining two or more kinds of synthetic resins which are substantially in the
form of a cross-section and which are different from each other. A non-woven fabric in which
extremely long and thin fibers are entangled, which is obtained by dividing with a high-pressure
water stream, is used as the speaker diaphragm.
[0010]
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Further, as a method of manufacturing the diaphragm for a speaker, a non-woven fabric
composed of long fibers of two or more types of synthetic resin fibers having different melting
temperatures is close to the melting temperature of the synthetic resin fibers having the lowest
melting temperature among the synthetic resin fibers. It is characterized by radiant heating so
that it may become, and press-molding at normal temperature immediately after that.
[0011]
In the speaker diaphragm of such a configuration, a non-woven fabric composed of long fibers of
two or more types of synthetic resin fibers having different melting temperatures is used to melt
the synthetic resin fibers having the lowest melting temperature among the synthetic resin fibers.
Since it is molded by heating and pressing near the temperature, the long fiber does not stop the
fiber state inside the non-woven fabric like the one molded by heating and pressing at the
melting temperature (the fiber layer of the mold contact portion melts The diaphragm is not
formed in the state where the film is formed on the molded product, in other words, the film is
formed on the surface), but the long fibers are entangled in a state where the shape is almost
maintained. Since the cross points of the respective long fibers are pressed near the melting
temperature, they are fused to fix the long fibers.
Therefore, the molded product has a large thickness, that is, high rigidity.
Then, since the long fibers themselves are hardly melted, the solidification and cooling time of
the molded product is reduced, and release from the mold can be easily performed.
Furthermore, among the plurality of synthetic resin long fibers, only the intersection points of
one kind of synthetic resin long fibers are melted, and the long fibers of the other resins are kept
in a completely unmelted state, so even after molding The shape is maintained by the other long
fibers and no deformation such as contraction occurs.
[0012]
The composite long fiber having a substantially circular cross section is configured by combining
the non-woven fabric used for the speaker diaphragm with two or more types of synthetic resins
having substantially bowl-shaped cross sections so as to be different from each other. In the case
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of a non-woven fabric in which extremely long fibers are entangled, which is obtained by dividing
with a high-pressure water stream, entanglement of very long fibers further increases rigidity
and lowers the air permeability of the molded article. Furthermore, since the cross-sectional
shape of the extremely long fibers is substantially wedge-shaped, the contact area at the
intersection of the entangled long fibers is larger than that of the long fibers having a circular
cross section, whereby the strength and the rigidity are further improved. In this case, the
thickness is reduced as compared to the cross section circular long fibers, but since the long
fibers are arranged based on the shape, the long fibers are extremely clogged, The rigidity is
improved more than the reduction in thickness. In addition, ventilation is almost lost because of
this.
[0013]
The speaker diaphragm is radiantly heated so that the nonwoven fabric consisting of long fibers
of two or more types of synthetic resin fibers having different melting temperatures is close to
the melting temperature of the synthetic resin fibers having the lowest melting temperature
among the synthetic resin fibers. After that, when it is manufactured by pressure molding at
normal temperature immediately, the mold itself is not heated and molded but the radiation
heated nonwoven fabric is pressed with a metal mold at normal temperature, so the long mold
cooling time in the molding process It is not necessary. Furthermore, it is not necessary to reheat
the mold when forming a new diaphragm after forming.
[0014]
EXAMPLES The examples of the present invention will be described in detail. [Example] As
schematically shown in FIG. 1, a composite filamentous fiber 3 consisting of polyethylene
terephthalate 1 and polypropylene 2 and having a resin-like cross-sectional shape substantially
in the form of a ridge is alternately arranged to form a circular cross-section. Nonwoven fabric 4
(shown schematically in FIG. 2) in which the composite long fiber 3 thus obtained is divided into
a substantially bowl-like shape by a high pressure water flow and bipolar elongated fibers having
a fiber thickness of about 0.2 denier or less are entangled. Co., Ltd. Miracle cross]; clamp the
outer periphery of 300 g / m 2 in basis weight, 1.64 mm in thickness, 250 mm in width with two
metal rings 5 as shown in FIG. The two-sided heating is performed for 9 seconds with the set farinfrared heater 6. The distance h between the clamped nonwoven fabric 4 and the far-infrared
heaters 6a and 6b arranged above and below is set to about 20 cm. In the present embodiment,
the set temperature of the far infrared heater 6 is set to about 230 ° C., but in the apparatus of
the present embodiment, it may be set to 200 ° C. to 250 ° C. As for the heater setting
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temperature, the temperature of the non-woven fabric 4 set by the heater radiation heat is about
150 ° C. to about 160 ° C., which is close to the melting temperature of polypropylene, ie,
about 85% to about 90% of the melting point 176 ° C. of polypropylene. That is, it is set
according to the distance between the non-woven fabric 4 and the heater 6. Moreover, although
the heating time was 9 seconds in the apparatus of the present embodiment, molding was
possible with this apparatus within the heating time of 5 to 10 seconds.
[0015]
Within 2 seconds after completion of heating, press molding is performed for 10 seconds with a
pressing pressure of 10 kg / cm 2 with conical male and female molds 7a and 7b set to 15 ° C
to 20 ° C by water cooling, and a cone-shaped molded article Obtained. Although a water-cooled
mold was used in this embodiment, it may be carried out by using a mold at normal temperature.
The inner periphery and the outer periphery of this molded product were cut to obtain a coneshaped diaphragm having an outer diameter of φ115, an inner diameter of φ25 and a thickness
of 0.6 mm. [Comparative Example 1] Non-woven fabric consisting of extremely long fibers of
acrylic synthetic fiber; the outer periphery with a basis weight of 300 g / m 2, a thickness of 2.35
mm and a width of 250 mm was clamped by two metal rings and heated to 160 ° C. Hot press
molding for 10 seconds with a conical male and female mold. While the metal ring is pressed
against the lower mold, the upper mold is raised, and at the same time compressed air is blown
for about 20 seconds to cool, and the molded article surface is sufficiently cooled and solidified.
Release from. The inner periphery and the outer periphery of this molded product were cut to
obtain a cone-shaped diaphragm having an outer diameter of φ115, an inner diameter of φ25
and a thickness of 0.6 mm. [Comparative Example 2] Non-woven fabric consisting of extremely
long fibers of polypropylene fiber; Conical shape obtained by clamping an outer periphery with a
basis weight of 300 g / m 2, a thickness of 1.95 mm and a width of 250 mm with two metal
rings and heating to 150 ° C. Hot press molding for 15 seconds with a male and female mold of
While the metal ring is pressed against the lower mold, the upper mold is raised and, at the same
time, compressed air is blown for about 30 seconds for cooling, and the molded product surface
is sufficiently cooled and solidified. Release from. The inner periphery and the outer periphery of
this molded product were cut to obtain a cone-shaped diaphragm having an outer diameter of
φ115, an inner diameter of φ25 and a thickness of 0.6 mm. [Comparative Examples 3 and 4] As
Comparative Examples 3 and 4, an attempt was made to form a non-woven fabric composed of
very long fibers of acrylic synthetic fibers and polypropylene fibers used in Comparative
Examples 1 and 2 with the devices of Examples. Both molded articles of good shape were not
obtained. More specifically, since both non-woven fabrics are made of one kind of synthetic resin
long fiber, when the heating temperature is high when radiant heating, the long fiber is melted
and the shape of the sheet is not maintained at all, and this is the case Although the press
molding can not be performed, and the low temperature of the non-woven fabric does not soften
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sufficiently and a molded article having a good shape can not be obtained even if press molding
continues, the temperature setting is slightly changed and repeated attempts. A molded article of
good shape was not obtained.
[0016]
Next, the physical properties of this example and the respective physical properties of
Comparative Examples 1 and 2 are shown in Table 1.
[0017]
As apparent from Table 1, in the diaphragm of the example, the internal loss was slightly lower
than that of the diaphragms of Comparative Examples 1 and 2, but the Young's modulus was
high and the specific elastic modulus was extremely high.
[0018]
The cross section in the diaphragm of the present embodiment, an electron micrograph of the
surface is taken at FIG. 4 (photographed at 50 ×), FIG. 5 (photographed at 100 ×), the electron
micrograph of the cross section at the diaphragm of the comparative example is shown in FIG.
FIG. 7 (photographed at 100 ×) is shown respectively (photographed at 50 ×).
[0019]
In the diaphragm of this embodiment, the long fibers are hardly melted even at the surface and
the inside thereof, and the fiber shape remains stopped.
On the other hand, in the diaphragm of Comparative Example 2, although the unmelted part
remains in a part of the inside, the long fibers are almost melted on the surface and the inside,
and the structure is close to a film.
In addition, since the fiber shape was the same as in Comparative Example 2 also in Comparative
Example 1, the photograph was omitted.
[0020]
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The difference in the shape of the fibers mentioned above affected the release operation after
molding.
That is, in the case of Comparative Examples 1 and 2, since the fiber is melted during mold
release, the molded product bites into the mold and can not be easily removed, and the molded
product is deformed by the mold release. There were a lot of things to do. On the other hand, in
the case of this example, the mold release operation was good, and no deformation of the molded
product was observed. The reason why the diaphragms of Comparative Examples 3 and 4 can
not be formed by the apparatus of this embodiment is that, as described above, these
Comparative Examples are constituted by one kind of synthetic resin long fiber, that is, It is
considered that this is because the other synthetic resin long fibers which maintain the shape as
the non-woven fabric at the time of radiation heating of the non-woven fabric are not present.
[0021]
Next, FIG. 8 shows a frequency characteristic diagram of the diaphragm of the present
embodiment, and FIG. 9 and FIG. 10 show frequency characteristic diagrams of the diaphragms
of Comparative Examples 1 and 2, respectively.
[0022]
As is apparent from these characteristic diagrams, in the diaphragm of this example, a sharp
peak is generated due to resonance occurring over 3 kHz to 8 kHz (particularly 3 kHz to 5 kHz)
in the diaphragm of Comparative Examples 1 and 2. There is no flat frequency characteristic.
In this case, since the diaphragm of the present embodiment has a structure in which long fibers
having a cross-sectional ridge shape are accumulated and different resin long fibers are
intertwined, resonance is concentrated to one frequency. It is thought that they are dispersed
without
[0023]
As mentioned above, although the speaker diaphragm according to the present invention has
been described in detail based on the embodiment considered to be representative, the
embodiment of the speaker diaphragm according to the present invention may be a dome type
diaphragm instead of a cone type diaphragm. Also, the speaker may be a dust cap which works in
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the same manner as a diaphragm in the speaker. Furthermore, in this embodiment, polyethylene
terephthalate having a melting point of 256 ° C. and polypropylene having a melting point of
176 ° C. are used as synthetic resin long fibers having different melting temperatures. Although
it is used, other synthetic resin long fibers having different melting temperatures may be
combined, or three or more types of synthetic resin long fibers may be used, and the present
invention is not limited to the structure of the above example. It is possible to appropriately
modify and carry out as long as it has the configuration requirements described in the appended
claims, exhibits the action according to the present invention, and has the effects described
below. .
[0024]
The speaker diaphragm according to the present invention has the following effects.
(1) Since the long fibers are entangled with almost maintaining their shape, and the cross points
of the entangled long fibers are pressed near the melting temperature, they are fused, thereby
fixing the long fibers. The thickness is large, that is, the rigidity is high. For this reason, even
when a large-input bass signal is applied to the speaker, uniform piston movement is performed.
(2) Since the diaphragm shape can be maintained by fusing at the intersections of the respective
long fibers to be entangled and fixing these long fibers, the conventional impregnation becomes
unnecessary, and the manufacturing process is simplified. (3) Since the long fibers are formed
with almost no melting, the cooling time of the molded product is reduced in the manufacturing
process, and release from the mold can be easily performed, which is excellent in workability. (4)
Among the plurality of synthetic resin long fibers, only the intersection point of one kind of
synthetic resin long fibers is melted, and the long fibers of the other resins are kept in the
unmelted state at all, so even after molding The shape is maintained by the long fibers, no
deformation such as contraction occurs, and the dimensional stability after molding is excellent.
(5) It can be obtained by dividing a composite filament having a substantially circular crosssection, which is formed by combining two or more types of synthetic resins that are
approximately in a cross-section having a plurality of types of synthetic resins different from
each other. In addition, in the case of using a non-woven fabric in which extremely long fibers
having a cross-sectional ridge-like shape are entangled, the rigidity is further improved by
intertwining ultra-long thin fibers having a substantially wedge-like cross section and increasing
the contact area of the intersections between long fibers. In addition, since there is almost no air
permeability of the molded product, there is no sound loss before and after the diaphragm, and
sounds of opposite phases radiated from the front surface and the rear surface of the diaphragm
cancel each other by sound loss to reduce the sound pressure level. And can achieve high sound
pressure levels. (6) Furthermore, in the case of the cross-sectional ridge-like long narrow fibers,
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since the cross-sectional ridge-like long fibers are deposited and the different resin long fibers
are intertwined, the resonance is concentrated to one frequency. Also, no sharp peak due to
resonance in the high frequency band occurs, and flat frequency characteristics can be obtained.
[0025]
In addition, the method of manufacturing the speaker diaphragm of the present invention has the
following effects. (1) The non-woven fabric comprising long fibers of two or more types of
synthetic resin fibers having different melting temperatures is radiantly heated to be near the
melting temperature of the synthetic resin fibers having the lowest melting temperature among
the synthetic resin fibers, and then immediately heated at room temperature Since pressure
molding is performed, a long mold cooling time in a conventional molding process is not
necessary, and molding can be performed in a short time, so that the workability is excellent. (2)
When forming the next diaphragm after forming the diaphragm, there is no need to reheat the
mold as in the prior art, and since molding can be performed one after another without this time,
mass productivity is excellent.
[0026]
Brief description of the drawings
[0027]
FIG. 1 is a view for explaining a composite long fiber before preparation of a non-woven fabric
used in the speaker diaphragm of the embodiment.
[0028]
The figure explaining the nonwoven fabric used with the diaphragm for speakers of the FIG. 2
Example.
[0029]
FIG. 3 is a view for explaining a forming process of the speaker diaphragm of the embodiment.
[0030]
FIG. 4 is an electron micrograph (× 50) showing the shape of fibers in the cross section of the
speaker diaphragm of the embodiment.
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[0031]
FIG. 5 is an electron micrograph (× 100) showing the shape of fibers on the surface of the
speaker diaphragm of the embodiment.
[0032]
FIG. 6 is an electron micrograph (× 50) showing the shape of fibers in the cross section of the
speaker diaphragm of Comparative Example 2;
[0033]
FIG. 7 is an electron micrograph (× 100) showing the shape of fibers on the surface of the
speaker diaphragm in Comparative Example 2.
[0034]
FIG. 8 is a frequency characteristic diagram of the speaker diaphragm of the embodiment.
[0035]
9 is a frequency characteristic diagram of the speaker diaphragm of Comparative Example 1.
[0036]
10 is a frequency characteristic diagram of the speaker diaphragm of Comparative Example 2.
[0037]
Explanation of sign
[0038]
Reference Signs List 1 polyethylene terephthalate long fiber 2 polypropylene long fiber 3
composite long fiber 4 non-woven fabric 5 metal ring 6 heater 7 mold
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