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The present invention relates to a speaker diaphragm, and more particularly, to provide a
speaker diaphragm having low gas permeability, that is, excellent in airtightness. Recently,
attempts have been made to seal gases other than air in the speaker cabinet in order to expand
the low frequency reproduction limit in a small speaker system. This is a method of using, for
example, a gas having a smaller specific heat ratio than air, such as fluorocarbon 114, or
achieving gas-liquid two-phase equilibrium in a cabinet to utilize phase transformation between
the gas-liquid two phases. In this way, in the speaker system in which the gas other than air is
sealed, the sealed gas is released if the air tightness is not perfect, and it does not endure longterm use. The air tightness can be solved relatively easily by bonding a metal foil to the surface
or using a metal molded product for the cabinet, but the speaker diaphragm is required to have
air tightness at the time of rf resonance Therefore, the realization was difficult. In particular, the
edge in the free-edge diaphragm and the fixed-edge diaphragm can have large amplitude in the
low region, and the stiffness is small, and it is required to be a @ amount. The realization of the
edge that was also prepared was required. Conventionally, paper, cloth, polyurethane, rubber and
the like have been mainly used as the edge material. Not to mention paper and cloth, even
materials seemingly airtight such as polyurethane and rubber were still not sufficient in terms of
gas permeability. The present invention solves such conventional drawbacks, and provides an
edge made of polyvinylidene chloride or a laminate of polyvinylidene chloride and a base
material. According to this 1'1 configuration, it is possible to obtain a loudspeaker diaphragm
having a small stiffness as an acoustic characteristic and a good airtightness. Polyvinylidene
chloride is known as a material having a small gas permeability, but similarly, polyethylene
terephthalate and polyacid having a small gas permeability are hard, and have a drawback that
noise is generated at the time of vibration / this time. In comparison, polyvinylidene chloride is
flexible and excellent as an edge material. Hereinafter, the present invention will be described
with reference to the drawings of the embodiments. FIG. 1 shows an embodiment of the present
invention, in which 21: a plate; 2, an annular magnet provided on the lower plate 1; and 3, an
annular upper plate provided on the magnet 2. A predetermined magnetic gap is formed between
the outer peripheral surface of the center pole and the inner peripheral end surface of the upper
plate 3.
4 is a frame provided on the upper plate 3; 5 is a free edge diaphragm supported so as to allow
piston movement on the frame 4; 6 is a bobbin provided on the central lower surface of the
diaphragm 6; 6 is a damper for supporting the Povin 6 on the L frame 4. The voice coil 7 is
supported so as to be capable of piston movement in the magnetic gap. The above-mentioned
free-edge diaphragm 5 is formed by joining the aluminum honeycomb core as a core material
and aluminum foil as a surface material on both sides, as shown in FIG. And a laminate of a
polyurethane elastomer sheet 11 and a polyvinylidene chloride sheet 12. Here, 1.1-edge]] 9 is
the thermal lamination of 2ooμ polyurethane elastomer sheet and 12μ polyvinylidene chloride
film through pound melt adhesive, and then polyvinylidene chloride film contacts gas in cabinet
Molded in the same way. ポリj3. <Modification of vinylidene fluoride, f-film is because the
gas which has permeated the inner membrane can not permeate the polyvinylidene chloride film
and is accumulated between the membranes to peel off the laminate. The edge was adhered to a
honeycomb face diaphragm having a surface material of A /, and the fluorocarbon 113 was
sealed and attached to a cabinet whose temperature was kept at 48 ° C., which was compared to
polyvinylidene chloride film. The edge had a transmittance of 1/1 or less as compared with the
conventional polyurethane alone. Next, when the polyurethane elastomer sheet was made 1 ooμ
and the polyvinylidene chloride film was made 20 μVC, the transmittance was decreased by
about 1/2 by no change at the edge and the characteristics of C were not changed. Although the
polyurethane elastomer sheath material is used in this embodiment, it is needless to say that
cloth or paper may be used instead. Since a polyvinylidene chloride film is usually stretched, it
shrinks upon heating. Therefore, it is necessary to sufficiently remove the stretching before
laminating. For that purpose, the substrate may be coated with a polyvinylidene chloride latex to
eliminate the problem of shrinkage due to stretching. For example, a polyurethane elastomer may
be used as a substrate, and a poly (IJ) vinylidene chloride latex may be applied to a thickness of
about 10μ and dried by a predetermined method, in which case another latex may be used to
form a polyvinylidene chloride layer. Or by spraying.
If you want to increase the thickness of polychlorinated vinyl chloride IJ, it may be overcoated. If
formed in this way, good airtightness can be secured without shrinkage and breakage of the
polyvinylidene chloride layer during molding. In addition, since good adhesion can be ensured
without the use of an adhesive layer in November, IIO! fti: And it can be used for small edges of
stiffness. In the above examples, molding was carried out after laminating or coating-). This can
be formed without breaking at a normal roll edge, but when forming an edge having a V-shaped
cross section as shown in FIG. 3 in order to make the linearity of the edge two , the corner
portion The thickness gets thinner and thinner, and the transmittance increases even if it is not
torn or torn. In order to solve this problem, it is sufficient to first form only the V-shaped
substrate 21 and immerse the molded article in latex to form a skin 1--J--. At this time, the film
thickness can be adjusted by the concentration of the solid content of the latex. If formed in this
manner, the thin portion 23 'v of the base material is also adhered with latex uniformly, so that
the airtight low profile is eliminated. Also, even if a spray is used instead of the immersion
method, application by brush 11 or the like may be performed. FIG. 4 shows an embodiment of
the song according to the present invention, and in FIG. 1, the same reference numerals indicate
the same components. Here, the difference from the one in FIG. 1 is that the fixed-edge
diaphragm 1o is used as a vibration lil + plate. The fixed-edge diaphragm 10 is formed integrally
with the diaphragm portion 1oa and the edge portion 10b, and is advantageous in terms of
weight and cost as compared to the free-edge diaphragm. Specifically, as shown in FIG. 5a, the
fixed-edge diaphragm 1o is manufactured by molding the received propylene foam sheet 31. As
shown in FIG. 5, the foam layer is formed as shown in FIG. It is pressed into a flexible
polypropylene film 31 '. The vibrating plate was coated with polyvinylidene chloride latex 32.
This made it possible to make the transmittance larger than that of polypropylene alone. It is a
matter of course that polyvinylidene chloride may be formed by lamination or coating before
molding, or may be formed into a film by a dip J- method such as immersion spray or coating
after molding. I: As described in detail, according to the present invention, since the edge formed
of polyvinylidene chloride, or a laminated weir made of polyvinylidene chloride and another
material-embedded base is provided, stiffness as acoustic 411 is small. And has an advantage of
being able to obtain a speaker diaphragm excellent in air tightness, and is particularly suitable
for a speaker system that seals a gas other than air in a speaker cabinet to expand the low
frequency reproduction limit. It is 0
Brief description of the drawings
FIG. 1 is a cross-sectional view showing an embodiment of the present invention, FIG. 2 is an
enlarged cross-sectional view of its main part, and FIG. 3 is an enlarged cross-sectional view of its
main part showing an embodiment of the pond of the present invention Yet another real of the
invention / If!
FIG. 5 is an enlarged sectional view of an essential part of FIG. 6 ······ Free-edge diaphragm, 9
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material, 12.32 ′ ..... Polyvinylidene chloride layer. Name of Agent Attorney Nakao Toshio Other
1 person Figure 1 Figure 3 Figure 1 23 'Figure 4 ((b)