JPS58154996

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DESCRIPTION JPS58154996
[0001]
The present invention relates to a speaker diaphragm in which an edge portion is integrally
formed on the outer periphery of the diaphragm portion, and the purpose thereof is to use the
same material for the diaphragm portion having high bending rigidity and the edge portion
having large internal loss. It is an object of the present invention to provide a speaker diaphragm
that can be formed simultaneously with use. In general, paper has often been used as a material
for speaker diaphragms. This is because the paper has low density and excessive specific elastic
modulus, 5 bending stiffness, and internal loss properties. The physical properties of the paper
are the efficiency as acoustic characteristics, the reproduction frequency band, the input
resistance, the strain 1 It is closely related to the flatness on the frequency characteristic.
However, in the case of paper, thermoforming can not be carried out, so there are two methods:
sheeting into a cone shape one by one, or molding with a hot mold in a state in which water is
sufficiently absorbed after being laminated once into a cone shape. However, there are many
cases where either method relies on a rattan craftsman machine, and there is a drawback that the
density varies greatly between lofts. Therefore, recently, metal materials such as aluminum and
beryllium, and polymer materials such as polypropylene and polyethylene have come to be used
as materials to replace paper. However, as a material of the speaker diaphragm, light weight and
high rigidity are required, and it is difficult to meet this requirement with a single material,
including structural elements such as a three-layer structure. The development of materials is
being carried out. On the other hand, although the edge material is required to have high internal
loss, high rigidity and high internal loss of the characteristics required for the diaphragm
material and the edge material are contradictory. For this reason, there is a very difficult problem
in satisfying these physical properties and simultaneously forming the diaphragm portion and
the edge portion. The present invention solves such conventional problems, and provides a threelayered structure by providing an ultraviolet curable resin layer containing a reinforcing material
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on both surfaces of the diaphragm portion of the thermoplastic resin foam sheet. According to
this configuration, it is possible to simultaneously thermoform the three-layered diaphragm
portion and the edge portion of the outer periphery of the diaphragm portion. In addition, it has
a three-layer structure by applying and curing an ultraviolet curable resin composited with a
reinforcing material on both sides of the diaphragm portion of a thermoplastic resin foam sheet,
and a diaphragm portion having a large rigidity can be obtained. While being able to make an
edge part into a state with a large internal loss from a foam as it is to a molten film-formed state
by the thermoplastic resin foam sheet used, an edge part with a large internal loss can be
obtained 8 Hereinafter, the speaker and the diaphragm of the present invention will be
specifically described by way of examples.
Example 1 A 1 mm thick, 16 times foamed polypropylene foam sheet was heated for several
seconds using a far-infrared heater, and when it was sufficiently softened, press molding was
carried out, as shown in FIG. The diaphragm 3 integrally provided with the part 1 and the edge
part 2 was obtained. The press die at this time has a gap of about 0.3 mm in the diaphragm
portion, and a die having a gap in the edge portion is used for the diaphragm portion 1 of the
diaphragm 3 thus obtained. A UV curable resin (3022 made by Three Bond) in which 5% of mica
(3253 by Kuraray) is compounded on both sides by a weight ratio is applied at a ratio of 20 g /
r'r1 '' The ultraviolet curing resin was cured, and the diaphragm 1 was made to have a threelayer structure having mica-containing ultraviolet curing resin layers 5 and 6 on the front and
back of the foam sheet 4 as shown in FIG. Physical properties of the diaphragm portion and the
edge portion of the diaphragm thus obtained are shown in Table 1. Table 1 shows the physical
properties of the diaphragm portion and the edge portion of the diaphragm in the case of using
paper in the case of using an ultraviolet curable resin in which mica as a reinforcing material is
not complexed yet. Table 1 Also, FIG. 3 shows frequency characteristics when each of the abovedescribed diaphragms is incorporated into a speaker. In FIG. 3, a solid line a represents sound
pressure frequency characteristics of a diaphragm using paper, a broken line represents sound
pressure frequency characteristics of a diaphragm using a foam sheet having a non-reinforcing
UV curable resin layer, and a dashed dotted line C represents actual implementation. It is a sound
pressure frequency characteristic of an example diaphragm. As is apparent from FIG. 3, the
diaphragm reinforced with mica as a reinforcing material of this example had a high specific
modulus, and the high-frequency reproduction was good. In addition, the strain was small
because the flexural rigidity was large. Example 2 The physical properties of the diaphragm
portion of the diaphragm obtained in exactly the same manner as in Example 1 were reinforced
except that carbon fibers with a weight ratio of 3% and aramid fibers with a weight ratio of 3%
were used as reinforcements. The effect of the reinforcing material of Table 2 shown in Table 2
together with the case where no material is used is in proportion to the addition amount, and the
effect is larger as the addition amount is larger. However, the greater the addition amount, the
more the transmission of ultraviolet light is impeded and the curing of the resin is impeded. In
the case of this example, when the carbon fiber and the aramid fiber were added by 6% or more
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by weight ratio, the curing of the resin was significantly hindered. Therefore, the addition amount
of carbon fiber and aramid fiber as a reinforcing material is considered to be a range that can be
practically used within 5 inches by weight ratio. In Examples 1 and 2, although the thermoplastic
resin foam body is thermoformed as a diaphragm integrally including the diaphragm portion and
a part of the edge, and then the UV curable resin is applied and cured, the UV curable resin is
used. It is needless to say that the UV curable resin can be cured on both sides of the foam sheet
and then thermoformed on the diaphragm by the same method as in the embodiment, as
appropriately selected, according to the present invention as described in detail above. For
example, in order to form a three-layer structure by applying and curing a UV curable resin
reinforced with a reinforcing material on both surfaces of the diaphragm portion of the
thermoplastic resin foam sheet, by thermoforming with the diaphragm portion having a large
bending rigidity It is possible to obtain a diaphragm integrally provided with an edge portion
having a large internal loss.
In addition, since the material of the diaphragm is a thermoplastic resin foam sheet, the
diaphragm and the edge can be thermoformed simultaneously.
[0002]
Brief description of the drawings
[0003]
FIG. 1 is a cross-sectional view showing an embodiment of the speaker diaphragm of the present
invention, FIG. 2 is an enlarged cross-sectional view of the main part of the diaphragm, and FIG. 3
is a sound pressure frequency of the diaphragm and the conventional diaphragm. It is a
comparison curve figure of a characteristic.
1 · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · thermoplastic resin foam
sheet, 6, 6 · · · .... UV curable resin layer with reinforcing material. Name of agent Attorney Nakao
Toshio Other 1 person Figure 1 Figure 2 Deprivation 3
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