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JP2005236840

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DESCRIPTION JP2005236840
An object of the present invention is to obtain a diaphragm of a speaker having good acoustic
characteristics. A sheet-like crystalline thermoplastic film is heated by a heater as a film material
1a, and then the crystalline thermoplastic film is formed into a predetermined shape by a
forming means to obtain a speaker diaphragm. The method for producing a diaphragm, wherein
the heating temperature by the heater 8 is in the vicinity of the melting point of the crystalline
thermoplastic film, and the crystalline thermoplastic film is formed into a gel from a sheet to
form the inside of the film material 1a after forming. Residual stress can be reduced. As a result,
distortion can be reduced, and a loudspeaker diaphragm having good acoustic characteristics can
be obtained. [Selected figure] Figure 1
Method of manufacturing diaphragm for speaker and diaphragm for speaker using this
manufacturing method
[0001]
The present invention relates to a method of manufacturing a speaker diaphragm used for
various acoustic devices and a speaker diaphragm manufactured using this manufacturing
method.
[0002]
Hereinafter, a conventional speaker diaphragm will be described.
[0003]
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As a conventional molding method of a speaker diaphragm, for example, a method of press
molding has been used.
FIG. 4 is a cross-sectional view showing a conventional method of manufacturing a speaker
diaphragm, and a method of forming a diaphragm by press molding will be described using this.
[0004]
In FIG. 4, first, in order to manufacture a speaker diaphragm, a roll-shaped film material 1 such
as a polyetherimide film, polyethylene terephthalate, polybutylene naphthalate or the like is
stretched on a stage 2 into a sheet.
Next, the film material 1 is fed by the feed roller 7 to the lower mold 3 a of the mold 3 adjacent
to the stage 2. At this time, the lower mold 3 a of the mold 3 is heated by the temperature
regulator 5, and the film material 1 is heated in contact with the heated lower mold 3 a of the
mold 3. Thereafter, the film material 1 is pressed by the upper mold 3b of the mold 3 heated by
the temperature adjuster 6, and is molded as desired. Furthermore, the film material 1 is sent to
the lower die 4a of the punching die 4 by the feed roller 7, and by lowering the upper die 4b of
the punching die 4, unnecessary portions of the film material 1 are cut off and removed. I was
getting the diaphragm for.
[0005]
As prior art document information related to the present invention, for example, Patent
Document 1 is known. Japanese Utility Model Publication 1-65587
[0006]
The above-described conventional method for manufacturing a speaker diaphragm has a
problem that a speaker diaphragm having good acoustic characteristics can not be obtained. That
is, the conventional method does not sufficiently heat the interior of the film material 1. For this
reason, internal stress remains in the film material 1 after molding, and a vector for the film
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material 1 to return to a sheet shape is generated (this is called a spring back phenomenon).
[0007]
As described above, when pressed from top to bottom by the upper mold 3b, the film material 1
generates a vector that tends to return from the bottom to the top. First of all, the speaker
diaphragm vibrates in the vertical direction by the voice coil. The vector of vibration by the voice
coil is combined with the vector by springback when the speaker diaphragm vibrates upward,
and contradicts with the vector by springback when vibrating downward. As a result, distortion
occurs in the vibration of the speaker diaphragm, and the acoustic characteristics deteriorate.
[0008]
Therefore, an object of the present invention is to obtain a diaphragm of a speaker with less
distortion and good acoustic characteristics.
[0009]
In order to solve the above-mentioned conventional problems, according to the present invention,
in particular, the heating means heats the crystalline thermoplastic film to the vicinity of the
melting point of the crystalline polymer and loosens the intermolecular bonding of the crystalline
portion of the crystalline polymer A gel state in which the molecular motion of the amorphous
part becomes active is formed, and it is molded into a predetermined shape by a molding means
in this heated state.
[0010]
The effect of the method for manufacturing a speaker diaphragm of the present invention is that
a speaker diaphragm having good acoustic characteristics can be obtained.
That is, a thermoplastic film is used as a film material, which is heated to near the melting point
before molding to make the thermoplastic film into a gel.
As a result, the bonding of the crystalline polymer is broken, and the molecular motion of the
noncrystalline portion becomes active, and molding is performed in this heated state, and when
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the temperature after molding is lowered, the polymers are bonded in a predetermined shape.
Therefore, the residual stress in the film material is reduced. For this reason, the speaker
diaphragm of the present invention is unlikely to generate a spring back phenomenon. As a
result, distortion can be reduced, and a loudspeaker diaphragm having good acoustic
characteristics can be obtained.
[0011]
First Embodiment The first to eighth aspects of the present invention will be described with
reference to the drawings. The same reference numerals as in FIG. 4 denote the same parts as in
FIG.
[0012]
FIG. 1 is a cross-sectional view showing a method of manufacturing a speaker diaphragm in
accordance with the first exemplary embodiment of the present invention.
[0013]
First, as the film material 1a, used was a crystalline thermoplastic film whose main component is
obtained by condensation polymerization of a dicarboxylic acid and an aliphatic diol, or an
aliphatic glycol.
In this case, the crystallinity means a state in which the polymer compounds are regularly
arranged. On the other hand, the state in which the polymer compound is in a globular or
entangled state is referred to as amorphous or amorphous. Thus, the resin used as a film material
is divided into crystalline and amorphous from the top of the molecular arrangement, but in fact
there is no resin in which all parts are crystalline, and it may be said that it is crystalline. And the
crystal part and the amorphous part are mixed.
[0014]
Furthermore, since the molecular motion of the amorphous part becomes active at the boundary
of the temperature called the glass transition point (Tg) for both the crystalline polymer and the
amorphous polymer, the rigidity decreases accordingly.
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[0015]
In the case of the crystalline polymer used in the first embodiment, the crystalline portion exists
below the melting point and functions to fix the molecule, so that the decrease in rigidity
accompanying the temperature rise is smaller than that of the amorphous polymer. .
For this reason, it is preferable as a speaker diaphragm for vehicle mounting which heat
resistance is requested | required. If the melting point is exceeded, the crystals also disappear
and flow.
[0016]
In addition, the crystalline thermoplastic film which has as a main component the thing obtained
by condensation-polymerizing dicarboxylic acid and aliphatic diol, or aliphatic glycol is
inexpensive, and can form the film material 1a at low cost. In addition, the material thickness was
10 micrometers or more and 200 micrometers or less (a specific material is mentioned later).
[0017]
Next, a method of manufacturing the speaker diaphragm of Embodiment 1 will be described. For
example, when press forming is used as the forming means, first, the film material 1 a is
stretched in a sheet form on the stage 2. Next, the film material 1a is heated from sheet-like to
gel-like by a heater (an example of a heating means) 8 using far infrared rays such as a ceramic
heater. In the first embodiment, that the crystalline thermoplastic film is in the gel state is,
specifically, the temperature rise rate of 4 ° C./min, the tensile mode, and the deformation is ±
0.1%. In elastic temperature dispersion measurement, E '(storage elastic modulus) indicates a
state of 10E8 Pa or less.
[0018]
At this time, the heating temperature is set in the range of ± 50 ° C. by the temperature
regulator 9 around the melting point of the crystalline thermoplastic film used, and in this state,
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the lower mold of the mold 3 adjacent to the stage 2 The sheet is sent by the feed roller 7 to 3a.
At this time, the lower mold 3 a of the mold 3 is heated by the temperature regulator 5, and the
film material 1 a is heated in contact with the heated lower mold 3 a of the mold 3. Thereafter,
the film material 1a is pressed by the upper mold 3b of the mold 3 heated by the temperature
adjuster 6, and is molded as desired. Furthermore, the film material 1a is sent to the lower die 4a
of the punching die 4 by the feed roller 7, and the upper die 4b of the punching die 4 presses the
film material 1a to remove unnecessary portions, for the speaker Get the diaphragm. The forming
means may be formed by pressure forming or vacuum forming, in addition to the press forming.
[0019]
With the above-described configuration, it is possible to obtain a diaphragm of a speaker with
good acoustic characteristics. That is, a thermoplastic film is used as the film material 1a, and
this is heated to near the melting point before molding. Thereby, in the crystalline thermoplastic
film, the bonding of the crystalline polymer is loosened, and the molecular motion of the
amorphous portion becomes a gel state in which the molecular motion is active. It shape | molds
in this heating state, and when the temperature after shaping | molding falls, each polymer
couple | bonds with a predetermined shape. For this reason, the residual stress inside the film
material 1a decreases, and a spring back phenomenon caused by this stress hardly occurs.
[0020]
That is, even in the case of press molding from the top to the bottom by the upper mold 3b, a
vector that tends to return from the bottom to the top of the film material 1a does not easily
occur. The speaker diaphragm vibrates in the vertical direction by the voice coil. However, even
when it vibrates in the upward direction or in the downward direction, it is not affected by the
vector due to the springback, and distortion hardly occurs. As a result, distortion can be reduced,
and a loudspeaker diaphragm having good acoustic characteristics can be obtained.
[0021]
Further, by using a far-infrared heater such as a ceramic heater as the heater 8, it is possible to
obtain a speaker diaphragm having good acoustic characteristics. That is, heating of the material
containing a large amount of carbon and hydrogen can be carried out more efficiently in a short
time, and heating to near the melting point before forming the film material 1a makes the
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thermoplastic film from gel to sheet be able to. The heating by the far-infrared heater 8 can be
sufficiently heated to the vicinity of the inside in the thickness direction of the film material 1a
and is difficult to cool. Furthermore, in addition to the heating by the heater 8, since it is also
heated by the temperature regulator 5 at the time of molding, it is even more difficult to cool. As
a result, the residual stress is reduced even in the inside of the film material 1a after molding,
and the distortion can be reduced, so that a speaker diaphragm with good acoustic
characteristics can be obtained.
[0022]
Furthermore, specific materials of the film material 1a include polyethylene terephthalate
(hereinafter, PET), polybutylene terephthalate (hereinafter, PBT), a mixture containing both or
one of PET and PBT, polyethylene naphthalate (hereinafter, PEN) Etc. That is, these materials are
preferable in terms of cost and heat resistance. That is, although it is a crystalline thermoplastic
film, it has a Tg (glass transition temperature) of 50 ° C. or more and a melting point of about
230 to 270 ° C., which is suitable for this construction method, 110 ° necessary for mounting
on an automobile Meet C heat resistance. Also, PBT / PET mixture (generally referred to as BPET) and PEN are preferable in that they exhibit high internal loss and good acoustic
characteristics. In particular, B-PET can be produced at low cost. What is characterized in that the
film material 1a is PEN is an inexpensive film having high rigidity and high internal loss, which
satisfies wide band and stable characteristics.
[0023]
In the first embodiment, the material thickness of the film material 1a is 10 μm or more and
200 μm or less. However, 10 μm or more is because the film thickness is easily broken.
Further, the reason for setting the diameter to 200 μm or less is that if it is larger than this,
molding from pellets by the injection molding method can provide a diaphragm with less internal
residual stress. However, in the injection molding method, it is difficult to manufacture a
miniaturized speaker diaphragm having a complicated shape, and it is unsuitable as a method for
manufacturing a small diaphragm used for a receiver for a mobile phone or a micro speaker.
[0024]
For this reason, it is preferable to use press forming, pressure forming, vacuum forming or the
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like. Here, pressure forming refers to a method of applying pressure to the film material 1a using
air pressure or the like to press it against any one of the upper mold 3b and the lower mold 3a of
the mold 3. Also, with vacuum forming, when the space between the upper mold 3b and the
lower mold 3a of the mold 3 is closed, the film material 1a can be brought close to a vacuum
state, any of the upper mold 3b to the lower mold 3a of the mold 3 It refers to a method of
drawing in one side or forming. By using these forming methods, even if it is a small-sized
speaker diaphragm having a complicated shape as described in the second embodiment below,
the speaker diaphragm having less residual stress inside the film material and good acoustic
characteristics. Can be molded.
[0025]
Second Embodiment The invention according to the ninth to thirteenth aspects of the present
invention will be described below with reference to a second embodiment.
[0026]
FIG. 2 is a cross-sectional view of the speaker diaphragm in accordance with the second
exemplary embodiment of the present invention.
In addition, the material similar to Embodiment 1 was used for the film material 1a, and
description was simplified to the thing of the same structure.
[0027]
In FIG. 2, the diaphragm 10 is used for a tweeter having a deep part and a nearly vertical rising
part. That is, from the planar sheet-like film 1a, the drawing is too deep and it is difficult to form.
[0028]
Even in the case of the speaker diaphragm having a complicated shape as described above,
according to the manufacturing method of the present invention, it is possible to obtain a
speaker diaphragm having good acoustic characteristics. With the above-described configuration,
it is possible to obtain a diaphragm of a speaker with good acoustic characteristics. That is, a
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thermoplastic film is used as the film material 1a, and this is heated to near the melting point
before molding. Thereby, in the crystalline thermoplastic film, the bonding of the crystalline
polymer is loosened, and the molecular motion of the amorphous portion becomes a gel state in
which the molecular motion is active. It shape | molds in this heating state, and if the
temperature after shaping | molding falls, each polymer will recombine in a predetermined
shape. For this reason, the residual stress inside the film material is reduced, and a spring back
phenomenon caused by this stress is less likely to occur.
[0029]
For example, even in the case of press molding from the top to the bottom, it is difficult for the
film material 1a to generate a vector that tends to return from the bottom to the top. The speaker
diaphragm vibrates in the vertical direction by the voice coil. However, even when it vibrates in
the upward direction or in the downward direction, it is not affected by the vector due to the
springback, and distortion hardly occurs. As a result, distortion can be reduced, and a
loudspeaker diaphragm having good acoustic characteristics can be obtained. In the second
embodiment as well, the fact that the crystalline thermoplastic film is in the gel state specifically
refers to the state described in the first embodiment.
[0030]
Furthermore, when a forming method such as pressure forming or vacuum forming is used as
the forming means, the rising portion close to the vertical, which is the central portion of the
diaphragm 10, prevents the thinning of the material generated by stretching at the time of
forming. Can. As a result, it is possible to prevent the reproduction band from being reduced
without deteriorating the shape rigidity of the portion required for the high range reproduction.
As a result, it is possible to obtain a speaker diaphragm having good acoustic characteristics.
[0031]
In the reliability test in which the diaphragm 10 is left in an atmosphere at 105 ° C. for 240
hours, no deformation occurs and it is proved that no residual stress at the time of molding
remains, and the heat resistance is supported. It is done.
[0032]
FIG. 3 is a perspective view of a speaker diaphragm in accordance with a third exemplary
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embodiment of the present invention.
[0033]
In FIG. 3, the outer periphery of the diaphragm 11A has a track shape of a sports facility, and in
the inside of the track shape, vibration of a plane shape is formed between the concave plate
portion 11a and the convex plate portion 11b. It is a small-sized slim type speaker diaphragm
having a small track-shaped inner periphery provided with a flat plate portion 11c and having an
improved shape rigidity and mainly used for a mobile phone or the like.
The diaphragm 11A is characterized in that its inner peripheral portion is a complicated shape
having a flat surface and a convex-concave shape and its outer periphery is a track type, so that
molding distortion, that is, residual stress is easily generated.
[0034]
Even in the case of the speaker diaphragm having a complicated shape as described above,
according to the manufacturing method of the present invention, it is possible to obtain a
speaker diaphragm having good acoustic characteristics.
That is, a thermoplastic film is used as the film material 1a, and this is heated to near the melting
point before molding. Thereby, in the crystalline thermoplastic film, the bonding of the
crystalline polymer is loosened, and the molecular motion of the amorphous portion becomes a
gel state in which the molecular motion is active. It shape | molds in this heating state, and if the
temperature after shaping | molding falls, each polymer will recombine in a predetermined
shape. For this reason, the residual stress inside the film material is reduced, and a spring back
phenomenon caused by this stress is less likely to occur.
[0035]
The diaphragm 11A having a circular shape with a diameter of 10 mm or less, the minor
diameter of the diaphragm having an elliptical shape with a diameter of 20 mm or less, and the
minor diameter of the diaphragm 11A having a track shape with a diameter of 20 mm or less
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The same effect can be obtained with the speaker diaphragm 11A characterized by the above. In
addition, by using the diaphragm manufactured by the manufacturing method of the present
invention, it is possible to provide a speaker diaphragm having a complicated shape with good
acoustic characteristics, to expand the reproduction frequency band to 70 kHz, and particularly
to improve the performance as a tweeter. There is.
[0036]
According to the method for manufacturing a speaker diaphragm of the present invention, it is
possible to obtain a speaker diaphragm having good acoustic characteristics. That is, by using a
thermoplastic film as a film material and heating it to near the melting point before molding to
make the thermoplastic film from a sheet to a gel, residual stress inside the film material after
molding is reduced. As a result, it is possible to reduce distortion and obtain a speaker diaphragm
having good acoustic characteristics, and it is useful as a speaker diaphragm used for various
acoustic devices.
[0037]
Sectional view showing a method of manufacturing the speaker diaphragm in accordance with
the first embodiment of the present invention Sectional view of the speaker diaphragm in
accordance with the second embodiment of the present invention A perspective view of the
speaker diaphragm in accordance with the third embodiment of the present invention Section
showing a method of manufacturing the speaker diaphragm of
Explanation of sign
[0038]
DESCRIPTION OF SYMBOLS 1 a film material 2 stage 3 molding die 3 a molding die lower die 3 b
molding die upper die 4 removing die 4 a removing die lower die 4 b removing die upper die 5
temperature regulator 7 feed roller 8 heater 9 temperature regulator 10 diaphragm
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