JPS63187900

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DESCRIPTION JPS63187900
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
speaker diaphragm having a sandwich structure with excellent frequency characteristics in the
high frequency range. [Prior Art] Generally, the characteristics required for a speaker diaphragm
are (a) small surface density, (ii) large specific elastic modulus E / ρ (E: elastic modulus, ρ:
density), ( C) It is required to have an appropriate internal loss (tan δ) and (d) to have a high
flexural rigidity. In particular, in the case of a cone-shaped diaphragm, a large specific elastic
modulus is required because the inner peripheral portion (voice coil side) must accurately
propagate the vibration of the voice coil bobbin. On the other hand, since the outer peripheral
portion (edge side) must absorb the reflection vibration from the edge, it is ideal that the internal
loss is moderately large. A conventional speaker diaphragm having a three-layer sand-inch
structure in which a skin material made of a thin film of fiber reinforced plastic is bonded to both
sides of a core material made of a core material such as a honeycomb core made of metal or
polymer thin film There is. And as a base material of the said skin material, what uses the woven
fabric which consists of carbon fiber, glass fiber, an aromatic polyamide fiber, etc. is proposed
(for example, Japanese Utility Model Laid-Open No. 56-43994). [Problems to be Solved by the
Invention] However, since the conventional speaker diaphragm having a three-layer sand-inch
structure based on carbon fiber or glass fiber has a large elastic modulus of the base material,
Although the specific elastic modulus is large and the structure is effective as a diaphragm, in
general, since the specific elastic modulus and the internal loss are in inverse proportion to each
other, the internal loss is small and the required characteristics as a speaker diaphragm are I
could not meet enough. In addition, the speaker diaphragm based on aromatic polyamide fiber
has larger internal loss and larger specific elastic modulus than the one based on carbon fiber or
glass fiber, but the ideal property level is reached There was a problem of not doing. The present
invention has been made to solve the above problems, and it is an object of the present invention
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to provide a speaker diaphragm which has a large specific elastic modulus, has a suitable internal
loss, and satisfies the characteristics required for a speaker diaphragm. The purpose is. [Means
for Solving the Problems] The speaker diaphragm of the present invention is a speaker vibration
having a three-layer sand-inch structure in which a skin material made of a thin film of fiber
reinforced plastic is bonded to both sides of a core material made of core material. In the plate, a
woven fabric made of metal-plated carbon fiber is used as a base material of at least one surface
material. As a core material which becomes a core material, core materials, such as a honeycomb
core which consists of a thin film of metal or a polymer material, can be used, and it is good also
as a structure which notched one part and increased flexibility.
The woven fabric serving as a base material of one or both skins adhered to both sides of the
core is composed of metal-plated carbon fibers. The metal to be plated is arbitrary, but nickel,
zinc, copper, tin and the like are preferable, and one or several of them are plated on the carbon
fiber. The thickness of the plating layer is preferably 0.05 to 0.5 μI. The plating is preferably
performed with maintaining the spacing between the single fibers with respect to the single
fibers or rovings of carbon fibers so that the plating layer is uniformly formed on the entire
surface of each single fiber. Thus, it is preferable to form a woven fabric such as plain weave
from roving and carbon fiber coated with metal in this way, and it is preferable to use it as a base
material of the skin material. When such a woven fabric is used as the base material of the
material, a woven fabric of conventional carbon fiber, glass fiber or the like is used as the base
material of the other skin material. These substrates are impregnated with a resin such as an
epoxy resin, and heated and pressed to cure the resin to form a fiber reinforced plastic, thereby
forming a skin material. Then, this skin material is laminated on both sides of the abovementioned core material and adhered to form a sandwich structure, whereby a speaker
diaphragm is obtained. [Operation] The speaker diaphragm thus obtained is attached to a
speaker frame, connected to a voice coil, and used in the same manner as the conventional one.
At this time, since the speaker diaphragm has a high specific elastic modulus, it faithfully
propagates the vibration of the voice coil bobbin and has an appropriate internal loss, so it
absorbs the reflection vibration from the edge and the frequency characteristic of the high
frequency range is Few. An embodiment of the present invention will now be described with
reference to the drawings. FIG. 1 is a cross-sectional view showing an embodiment, FIG. 2 is a
plan view of a substrate, and FIG. 3 is a cross-sectional view taken along the line A-A. In the
figure, (1) is a diaphragm for a speaker, which is formed in a cone shape, and skins (3) and (4)
are bonded to the inside and the outside of a core (2) made of a honeycomb core of aluminum
foil, It has a three-layer sand inch structure. The surface materials (3) and (4) are made of a
woven fabric (6) obtained by plain-weaving roving (5), which is an assembly of single yarns
metal-plated on carbon fibers, which is impregnated with resin and heated, It is hardened by
pressure and made into fiber reinforced plastic. A 0.1 μm nickel base plating is applied to a
roving consisting of carbon fibers with a diameter of 7 μm, and further a zinc plating of 0.1 μm
is formed to form a woven fabric by plain weave, which is impregnated with an epoxy resin and
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pressed. While curing by heating, surface materials (3) and (4) having a fiber volume content of
about 50% and a thickness of 0.12 a + m were obtained.
As the core material (2), an aluminum honeycomb core made of aluminum foil having a thickness
of 0.05 mm and having a cell size of 3/16 inch and a thickness of 3 mm was used. Further, the
skin materials (3) and (4) are bonded to both sides of the core material (2) with an adhesive
made of epoxy resin, and bonded by heating and pressure to obtain a speaker diaphragm of a
three-layer sand-inch structure. The The values of the specific elastic modulus E / ρ and the
internal loss tan δ obtained by the vibration reed method for the obtained specimen are shown
in Table 1. As a comparative example, Table 1 also shows the results of a three-layer sand-inch
plate based on a woven fabric consisting of carbon fiber and glass fiber roving, and a
conventional paper cone. As is apparent from Table 1, when using the skin material of the
present invention with metal-plated carbon fibers, the specific elastic modulus is approximately
the same as that of the conventional glass fiber, and the internal loss is the same as that of the
conventional paper cone. Similar to the conventional paper cone diaphragm, the piston
movement area can be expanded by about 2 times, and since the internal loss is large, the
frequency characteristic in the high frequency range is small, and the characteristic sound
unique to the honeycomb diaphragm disappears. It can be understood that a loudspeaker
diaphragm having a three-layer sandwich structure which is extremely effective can be obtained
from physical properties and hearing characteristics. [Effects of the Invention] As described
above, according to the present invention, since a woven fabric made of metal plated carbon fiber
roving is used as a substrate, the specific elastic modulus is large, the internal loss is appropriate,
and the frequency in the high range is A loudspeaker diaphragm having excellent characteristics
is obtained.
[0002]
Brief description of the drawings
[0003]
FIG. 1 is a cross-sectional view of an embodiment, FIG. 2 is a plan view of a substrate, and FIG. 3
is a cross-sectional view taken along the line A-A.
In each figure, the same reference numerals indicate the same or corresponding parts, (1) is a
speaker diaphragm, (2) is a core material, (3), (4) is a skin material, (5) is roving, (6) Is a woven
fabric.
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