JPS55107396

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DESCRIPTION JPS55107396
1Specification 1, Name of Invention
Speaker diaphragm
3. Detailed Description of the Invention The present invention relates to a speaker diaphragm
using synthetic pulp as a base material, and provides a speaker diaphragm having high rigidity
and high internal loss. The conventional speaker diaphragm is often made of paper. This is
because the paper has appropriate elastic modulus and internal loss, and can be reduced in
weight. Recently, metals such as organic foam and aluminum have been used as materials to
replace paper, but organic foams have small elastic modulus, and metal diaphragms have
advantages such as small internal loss and increased weight, It can not be said that it is optimal
as a speaker diaphragm. Also, in order to improve the elastic modulus of paper, a mixed vibration
plate with inorganic fibers or organic synthetic fibers has been developed, but a large
improvement in elastic modulus can not be expected. Furthermore, since the three diaphragms of
paper are hygroscopic, they are weak to humidity and are not suitable as diaphragms. EndPage:
A speaker diaphragm having an elastic modulus and an internal loss. Conventionally, the paper
making of synthetic pulp 1oo% has an elastic modulus. The bending stiffness was small and it
was poor to put it to practical use as a speaker diaphragm. Then, the composite pulp of the
synthetic pulp and the inorganic fiber or the organic fiber was tried, and it was confirmed that
the elastic modulus was improved. However, although the elastic modulus was greatly improved,
the internal loss was not so improved. The present invention greatly improves the elastic
modulus, the internal loss, and the bending rigidity by using a composite in which synthetic pulp
is used as a base material and mixed fibers are used in two layers. The "synthetic pulp" in the
present invention is made of polyethylene, polypropylene, nylon, polyacrylonitrile or the like as a
main raw material, and these are shorted and fibrillated. In addition, "inorganic fibers" used for
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compounding are carbon fibers and alumina fibers. Say glass fiber 1. "Organic fiber" 7 refers to
aromatic polyamide fiber, tunol fiber, etc. The thermoplastic film used for 2 ° \ lamination has a
modulus of elasticity, a curvature of ゝ, X10. The films used differ depending on whether the
rigidity is improved or the internal loss is improved. Generally used resins such as polyester,
polypropylene, nylon and polyurethane. Thermosetting resin refers to epoxy, polyester, phenol,
melamine, etc., and is intended to improve bending rigidity. Elastic modulus, flexural rigidity and
internal loss are greatly influenced by the proportion and type of fibers used in the two-layer
structure. Generally, two or three types of fibers are compounded in synthetic pulp, and it is baric
if it is a two-layer structure rather than a two-layer structure, but it is impossible to improve the
elastic modulus, bending rigidity and internal loss together is there.
If one improves, one decreases. The proportion of fibers used in the composite was 25 wt% at
maximum, and even if the proportion of fibers was increased, the modulus of elasticity only
decreased. Examples of the present invention will be described below. The synthetic pulp used in
the examples is a freeness of 230 m7i (Canadian freeness), a fiber length of 14 or less, and (7)
polyethylene short fibers. Example 1 Synthetic pulp and carbon fiber (80 + 20) were mixed and
formed into a sheet by using a round net sheet machine to prepare a first composite sheet. The
carbon fiber used is a short fiber with a fiber length of 3 w Ib and a diameter of 1 o.mu., using
acrylinide =, "IJ" as a raw material, and it is a fabric weight eofl'4 of the composite sheet. On the
other hand, similarly, synthetic pulp was mixed with 3 pieces of fiber length and 2 denier
aromatic periamide fibers (85; 15), and made into a sheet to prepare a second composite sheet
with a basis weight of 40 f 2. As shown in FIG. 1, two sheets of the first composite sheet 1 and
the second composite sheet 2 were combined and formed into a cone by heat pressing. The
temperature i of the heat press is 16 ° C., and the polyethylene short fiber which is a synthetic
pulp is melted to bond the two composite sheets 1 and 2 together. Example 2 Between the two
composite sheets 1 and 2 prepared in Example 1, as shown in FIG. The composite sheet 1, the
modified polyamide film 3, and the composite sheet 2 were integrated. Example 3 An epoxy resin
film of 10 J '/' x was sandwiched between two composite sheets prepared in Example 1 and
molded by heat pressing at 210 ° C. to melt polyethylene, which is a synthetic pulp. And cure
the epoxy resin film. The elastic modulus, flexural rigidity and internal loss of the composites of
Examples 1 and 2 mentioned above are shown in the following table in comparison with a
conventional paper cone. Table 1 EndPage: A speaker of 2 bores 1 ocym was assembled, and the
result of measuring the frequency characteristic of this speaker according to JIS-BOX is shown in
FIG. In FIG. 3, 7a indicates the characteristic of the speaker using the diaphragm of the first
embodiment, and b indicates the characteristic of the conventional speaker using the paper cone.
The present invention has the above-described configuration, and according to the present
invention, the elastic modulus 1 bending rigidity and the internal loss become large, and
according to the speaker using the diaphragm of the present invention, the reproduction band is
expanded. It is.
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4. Brief description of the drawings Fig. 1 is a cross-sectional view of a speaker diaphragm in one
embodiment of the present invention, Fig. 2 is a cross-sectional view of another embodiment of
the present invention, and Fig. 3 is a diaphragm of the present invention. A speaker using a
speaker and a conventional speaker using a paper cone. It is a sound pressure frequency
characteristic figure of power. 1.2 · · · · · · · composite sheet, 3 · · · · · · · · modified polyamide film.
・ To 1, Name of attorney Attorney Nakao and others 1 person Figure 1 Figure 2 Figure 3 = 7f I
provisional @ K ('Dr) EndPage: ３
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