JP2001245385

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DESCRIPTION JP2001245385
[0001]
TECHNICAL FIELD The present invention relates to a speaker diaphragm.
[0002]
2. Description of the Related Art As a material of a speaker diaphragm, a resin material such as
polypropylene having high internal loss and excellent in moldability, water resistance and
moisture resistance is used as shown in FIG. As shown, it is formed into a diaphragm having a
gate 7 at a dome-shaped central portion and a vibrating portion 6 having a constant thickness at
the center and a thick edge portion 5 for enhancing rigidity at the outer peripheral portion.
[0003]
In the structure of the conventional speaker diaphragm shown in FIG. 2 above, when the injection
molding mold nest is slightly deviated during injection molding and the mold cavity is slightly
deviated, filling from the gate 7 is performed. Since the produced resin is biased to the thick
portion of the uneven thickness vibrating portion 6 with low pressure loss, the edge portion 5 is
filled before the thin portion of the uneven thickness vibrating portion 6 is filled.
When the edge portion 5 is filled, the resin temperature decreases and the resin solidifies, so the
thin portion is not completely filled, and shorts and welds occur in the molded product. The
present invention aims to prevent the occurrence of shorts and welds.
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[0004]
SUMMARY OF THE INVENTION In order to solve this problem, the present invention provides a
speaker having a gate at a dome-shaped central portion and a vibrating portion having a constant
thickness at the center and a thick edge portion at an outer peripheral portion. In the resin
diaphragm for a resin, a thin-walled portion thinner than the thickness of the vibrating portion is
provided at the connection position of the vibrating portion and the edge portion.
[0005]
Thus, even if the cavity is slightly deviated, the resin filled from the gate is provided between the
oscillating portion and the edge portion after it flows to the thick portion of the oscillating
portion which is unevenly distributed. When the thin portion is reached, the pressure loss is high
in this portion, so the resin does not flow to the edge portion and the thin portion of the vibration
portion which is unevenly thickened is filled, and after the thin portion is filled, the edge portion
is filled.
When the vibrating portion is filled, the resin temperature is high and the resin has high
flowability and is not solidified, so that a speaker diaphragm having no short and no weld in the
vibrating portion can be obtained.
[0006]
The invention according to claim 1 of the present invention is directed to a speaker having a gate
at a dome-shaped central portion and a vibrating portion having a constant thickness at the
center and a thick edge portion at an outer peripheral portion. The resin diaphragm is
characterized in that a thin-walled portion thinner than the thickness of the vibrating portion is
provided at the connection position of the vibrating portion and the edge portion, and even when
the cavity is slightly deviated during molding, Since the resin filled from the gate flows to the
thick portion of the vibrating portion with uneven thickness and then reaches the thin portion
provided between the vibrating portion and the edge portion, this portion has a high pressure
loss. Since the resin does not flow to the edge part and the thin part of the vibrating part which is
unevenly thickened is filled, and after the filling of the thin part, the edge part is filled, it is
possible to obtain a speaker diaphragm having shorts and welds not Have.
[0007]
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The invention according to claim 2 is characterized in that the thin portion is 20% to 80% of the
thickness of the vibrating portion, and has the same function as the invention according to claim
1.
[0008]
Hereinafter, an embodiment of the present invention will be described with reference to FIG.
(Embodiment) FIG. 1 shows a speaker diaphragm of the present invention, in which 1 is a thick
edge portion, 2 is a vibrating portion of a constant thickness, 3 is a gate provided at a domeshaped central portion, 4 Is a thin-walled portion provided at the connection position of the edge
portion 1 and the vibrating portion 2.
[0009]
As an example of the thickness of each portion, when the thickness of the vibrating portion 2 is
0.05 mm, the edge portion 1 is 0.4 mm, the thin portion 4 is 0.03 mm, and the gate is 0.3 mm. In
this case, the thickness of the thin portion 4 is 3⁄5 of the thickness of the vibrating portion 2.
[0010]
When molded with a mold having a cavity of this shape, the resin starts to be filled from the gate
3 with a diameter of 0.3 mm first, and is narrowed to a thickness of 0.03 mm with high pressure
loss from the vibrating portion 2 with a thickness of 0.05 mm. When the thin portion 4 is
reached, the pressure of the vibrating portion 2 is increased and the whole vibrating portion 2 is
filled with the resin, and thereafter the edge portion having a thickness of 0.4 mm is filled.
When the vibrating portion 2 is filled, shorts and welds do not occur in the vibrating portion 2
because the resin temperature is high and the fluidity is high.
[0011]
The ratio of the thin part thickness to the vibrating part thickness is appropriately set according
to various conditions such as the temperature characteristics of the resin material, the
temperature at the time of resin filling, and the heating temperature of the mold, but generally
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20% to 80% Is most preferable.
[0012]
According to the present invention, even if the cavity is slightly uneven at the time of molding,
the resin filled from the gate flows after being unevenly flowed to the thick portion of the uneven
vibration portion. When the resin reaches the thin portion provided between the vibrating
portion and the edge portion, the resin does not flow to the edge portion, and after the thin
portion of the vibrating portion having the uneven thickness is filled, the edge portion is filled.
Even when the thin portion is present, since the thin portion is completely filled, a shortcircuited, weld-free speaker diaphragm can be obtained.
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