JPS63258198

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DESCRIPTION JPS63258198
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
speaker diaphragm having a sandwich structure excellent in frequency characteristics in 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) To have an appropriate internal loss-δ), it is required that the bending rigidity is high. In
particular, in the case of a cone-shaped diaphragm, a large specific elastic modulus is required
because the voice coil side must propagate the vibration of the voice film bobbin faithfully in the
inner peripheral portion (the voice coil side must be transmitted faithfully. On the other hand,
since the outer peripheral portion (edge @) has to 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 sandwich structure in which a skin material made of a thin film of fiber reinforced
plastic is adhered to both sides of eight cores made of a core play such as a honeycomb core
made of a thin film of metal or polymer material is there. 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 sandwich structure based on carbon fiber or glass fiber has a large elastic
modulus of the base material, the specific elasticity of the sandwich structure is In general, the
specific modulus and the internal loss are in inverse proportion to each other, so the internal loss
is small and the requirements for the speaker diaphragm are sufficiently satisfied. I could not. 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 There was a problem that it did not reach. The present invention has been made to
solve the above problems, and it is an object of the present invention to provide a speaker
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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 diaphragm having a
three-layer sandwich structure in which a skin material made of a thin film of delicate reinforced
plastic is adhered to both sides of a core material made of core material. In at least one of the
above, a woven fabric made of a nickel metal-plated aromatic polyamide fiber is used as a base
material of at least one surface material.
A core material such as a honeycomb core consisting of a thin film of gold R or polymer side
slope can be used as the core material to be the core material, and a part of the core material
may be cut away to increase the flexibility. The woven fabric serving as a base material of one or
both skins adhered to both sides of the core material is composed of nickel metal plated aromatic
polyamide fibers. As thickness of a plating layer, fia, os-Q, and 5 micrometers are preferred. The
plating is preferably performed with the spacing between the single fibers maintained with
respect to the single fibers or rovings of the aromatic polyamide fiber so that the plating layer is
uniformly formed on the entire surface of each single fiber. As described above, it is preferable to
form a woven fabric such as plain weave from rovings and to use it as a base material of the skin
material, but it is also possible to form a woven fabric from yarns. When such a woven fabric is
used as the base material of one skin material, a woven fabric of conventional carbon fiber,
aromatic polyamide fiber, glass fiber or the like is used as the base material of the other skin
material. These base materials are impregnated with a resin such as epoxy resin and heated and
pressed to cure the resin to form a fiber reinforced plastic to form a skin material. Then, this skin
material is laminated on both sides of the above-mentioned core material and adhered to form a
sandwich structure, whereby a speaker diaphragm is obtained. [Function] The speaker
diaphragm thus obtained is attached to the speaker frame, connected to the 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 thereof. In
the figure, (1) is a diaphragm for a speaker, which is formed in a cone shape, and the outer
surface *; 4 (31, +41 is adhered to the inside and the outside of the core material (2) made of a
honeycomb core of aluminum foil It has a layered sandwich structure. Skin @ (31, 141 is a woven
fabric of plain weave of roving (5), which is an aggregate of single yarns plated with nickel metal
on aromatic polyamide fibers, (61 is a base material, which is impregnated with resin, heated,
heated It is hardened by pressure and made into fiber reinforced plastic. A 0.1 μm nickel base
plating is applied to a roving made of aromatic polyamide fibers of diameter T μm.
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Further, a 0.1 μm nickel-plated product is woven into a woven fabric by plain weave,
impregnated with an epoxy resin, and heat-cured while being pressed to obtain a fiber volume
content of about 50% and a thickness of 0.12 dragon The skin @ (3), got +41. As the core
material (2), an aluminum honeycomb core made of an aluminum foil having a thickness of 0.05
fl and having a cell size of 3/181 nch and a thickness of 3 H was used. The above skin (6 N 31 °
14) was bonded to both sides of the core * 4 + 21 with an adhesive made of epoxy resin, and
heat and pressure were adhered to obtain a speaker diaphragm for a three-layer sandwich
structure. The values of the specific elastic modulus E / 損失 and the internal loss −δ obtained
by the vibration reed method for the obtained test piece are shown in Table 1. As a comparative
example, the results of a three-layer sandwich board based on a woven fabric consisting of
carbon fiber and glass fiber roving, and a conventional paper cone are also shown in Table 1. As
apparent from Table 1 and Table 2, when the skin material of the nickel metal plated aromatic
polyamide fiber of the present invention is used, the specific elastic modulus becomes almost the
same as that of the conventional glass fiber and the internal loss is the conventional one.
Compared to the conventional paper cone diaphragm, the piston movement area can be
expanded about twice as much as that of the paper cone, and the internal loss is large, and the
frequency characteristic in the high frequency range is small (the characteristic peculiar to the
honeycomb diaphragm The sound disappears, and it can be seen that a loudspeaker diaphragm
having a three-layer sandwich structure which is extremely effective can be obtained from the
viewpoint of physical properties and hearing characteristics. [Effects of the Invention] As
described above, according to the present invention, since the woven fabric made of nickel metal
plated aromatic polyamide fiber roving is used as the base material, the specific elastic modulus
is large ((1). It is possible to obtain a speaker diaphragm having an appropriate internal loss and
excellent frequency characteristics in the high frequency range.
[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 the drawings, the same reference numerals indicate the same or corresponding parts. +1+ is a
speaker diaphragm, 12) a tit core material, (3), 141 is a skin material, (5) is a roving, and 16I is a
woven fabric.
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