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JP2001145188

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DESCRIPTION JP2001145188
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
diaphragm for a speaker having improved acoustic characteristics by blending fine hollow glass
spheres with a synthetic resin material.
[0002]
2. Description of the Related Art The materials currently used as diaphragm materials for
speakers are paper, animal skin, cloth, metal material, etc. conventionally used, and synthetic
resin is used as a substitute material for these. Various diaphragms have been developed, each of
which brings about unique acoustic characteristics. Furthermore, various additives and modifiers
are added to the synthetic resin material to further improve the acoustic characteristics.
[0003]
The main characteristics required of a diaphragm for a speaker are its own lightness (lightness),
hardness (hardness) and high rigidity. A light diaphragm can quickly capture vibrations between
voice coils, so that the sound pressure can be increased, the surface density can be increased as
the hardness becomes higher, and the vibrations can be transmitted as sound waves with strong
rigidity.
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1
[0004]
Furthermore, the diaphragm itself does not generate abnormal vibration such as reverse
resonance, and characteristics such as having an internal loss for damping excessive vibration
are required.
[0005]
In the past, in order to reduce the weight, the acoustic characteristics have been improved by
various methods such as using a foaming agent or the like, blending additives, modifiers, and
fillers such as mica and calcium carbonate to obtain hardness and high rigidity. However, if the
diaphragm is made light by lowering its specific gravity, it is difficult to have the characteristics
required for the diaphragm in a well-balanced manner because the hardness and rigidity can not
be sufficiently obtained.
[0006]
Furthermore, as the additives and the like are compounded, the molding stability is deteriorated
and the quality is dispersed, and abnormal vibration such as reverse resonance is easily
generated.
[0007]
SUMMARY OF THE INVENTION The present invention has been invented to solve the above
problems and to provide a diaphragm having excellent acoustic characteristics with no variation
in quality.
[0008]
SUMMARY OF THE INVENTION In the present invention, an appropriate amount of fine hollow
glass spheres having a density of 0.8 g / cm2 or less and an average particle diameter of 100
μm or less are compounded into a synthetic resin material, and extrusion molding, injection
molding, compression molding, foam molding It is obtained by forming the diaphragm by the
forming method suitable for the purpose.
[0009]
The type of the synthetic resin material, the blending method, the molding method, and the
shape of the diaphragm in this case are selected and determined according to the purpose as a
diaphragm for a speaker, and they are not particularly limited.
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[0010]
The speaker diaphragm of the present invention thus obtained is characterized by having
excellent acoustic characteristics which have not been achieved in the prior art.
[0011]
BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be
described below.
FIG. 1 is a cross-sectional view of FIG. 2 showing a diaphragm for a speaker according to an
embodiment of the present invention.
[0012]
The present invention is a method such as injection molding in which minute hollow glass
spheres 2 are mixed and dispersed in a synthetic resin material layer 1 such as polypropylene,
polyethylene, polystyrene, polycarbonate, ABS resin, AS resin, polyurethane resin, liquid crystal
polymer etc. It is a diaphragm obtained by molding.
[0013]
Since the glass spheres 2 used in the present invention are completely hollow spheres of fine
glass having an average particle diameter of 100 μm or less, not only a lightweight property and
high rigidity which are not included in general fillers can be obtained, but also their dispersibility
is good. It also improves dimensional stability.
[0014]
Furthermore, since the hollow body has a large internal loss, reverse resonance and over
vibration can be prevented, and a loudspeaker diaphragm having good thixotropy and good
frequency characteristics can be obtained.
[0015]
Here, when it is molded with glass spheres having an average particle diameter exceeding claim
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1, although weight reduction and improvement in rigidity can be expected, a molded product
with sufficient strength and shape as a molded product can not be obtained gradually.
Further, glass spheres having a density exceeding that of claim 1 are not suitable for use in
diaphragms because they are contrary to weight reduction aimed at.
[0016]
The synthetic resin material and the method for producing glass spheres used in the present
invention are not particularly limited.
Further, by blending the additive, modifier, and filler 3 simultaneously with the present invention
such as mica, it is possible to obtain even higher characteristics as a diaphragm for a speaker.
[0017]
Examples of the invention will be given below.
Mica (C) and the above-mentioned fine hollow glass spheres (B) were sufficiently mixed in the
following ratio with the pellet material (B) of polypropylene resin to obtain Example [1] and
Example [2].
Moreover, the sample which does not mix | blend a micro hollow glass sphere (i) as a
comparative example, and the comparative example [1] were prepared.
[0018]
(A) Micro hollow glass spheres: density 0.4 g / cm 2, average particle size 55 μm (b)
polypropylene resin: specific gravity 0.9 g / cc, impact resistance good (c) mica: specific gravity
0.2 g / cc, average particle The reason that the diameter of 30 μm mica is blended at this time is
to obtain stronger surface hardness and rigidity, and this is a method for improving the acoustic
characteristics of the speaker diaphragm generally used conventionally.
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[0019]
The compounding ratio is as follows (all by volume ratio) Comparative Example [1]; (A): (B): (C) =
0%: 70%: 30% Example [1]; (B): (R) ): (C) = 15%: 65%: 20% Example [2]; (A): (B): (C) = 10%: 60%:
30% of these mixed materials in an injection molding machine The diaphragm for a speaker FIG.
2 was obtained by injection molding.
[0020]
The sound pressure frequency characteristics of the speaker diaphragm shown in FIG. 2 were
measured using the above.
The measurement method and conditions are shown below.
Measurement method: It conformed to JIS-C5531 standard.
Measurement conditions: The conditions defined in the JIS-C5531 standard were observed.
Measuring instrument: An instrument conforming to the JIS-C5531 standard was used.
The measurement was performed by the device of Onkyo Co., Ltd. design department anechoic
room.
[0021]
Although occurrence of a sharp dip is confirmed in the vicinity of 1.3 kHz in Table 1, this dip is
eliminated in Tables 2 and 3.
Since the sound pressure level is also flat and stable without extreme dips on the curve, a
significant improvement in the acoustic characteristics appears.
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It can be judged that the diaphragm of the embodiment [1] is suitable for a mid to high range
speaker having an acoustic characteristic without distortion.
[0022]
Furthermore, since the dip of around 10 kHz is eliminated in Table 2 and the sound pressure
level is stabilized in Table 3 and the limit frequency is also improved by about 5 kHz respectively
compared to Table 1, the higher frequency is obtained by combined use with a modifier etc. Also
in the above, it is possible to obtain a diaphragm which exhibits more stable acoustic
characteristics.
[0023]
According to the present invention, by blending minute hollow glass spheres with a synthetic
resin material, it is possible to easily obtain a speaker diaphragm of excellent acoustic
characteristics which can not be obtained by a conventional modifier or the like. .
[0024]
Further, by additionally using modifiers / fillers and the like conventionally used such as mica
and a foaming agent, it is possible to freely impart well-balanced acoustic characteristics which
are required more widely.
[Table 1] Sound pressure frequency characteristics measurement table of Comparative Example 1
of the present invention [Table 2] Sound pressure frequency characteristics measurement table
of Example 1 of the present invention [Table 3] Sound pressure frequency characteristics
measurement of Example 2 of the present invention table
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