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Description 1, title of the invention
Method of manufacturing diaphragm for acoustic device
Detailed Description of the Invention In the present invention, a synthetic resin and an FA house
powder are kneaded, then formed, heated and carbonized, and a diaphragm for an audio device
having low density and high elasticity can be easily produced. On the way. In general, a
diaphragm for audio equipment, particularly a thin plate used as a diaphragm of a speaker, is
light in weight, large in rigidity, and has a Young's modulus X and a density ρ in order to
reproduce efficiently and faithfully over a wide frequency band. A large ratio H / 比 is required.
Conventionally, wood pulp, synthetic resin, aluminum, titanium and the like have been used from
these points, but it has been difficult to say that all of them have sufficient properties. Also, as an
example using a carbon-based material, there is a composite material of carbon fiber and a
synthetic resin, but due to the lubricity of the surface possessed by the carbon fiber itself,
bonding of the carbon fiber by the synthetic resin is sufficient. Also, due to the large anisotropy
of the carbon fiber, a large rigidity as a surface has not been obtained like a diaphragm.
Therefore, the inventor focused on carbon by using a material that is light in weight, high in
rigidity, and high in ratio X / ρ of Young's modulus 2 to density と, and carbon, and was
anthracite or graphitized synthetic resin first. Vibrating plate: Although it was conceived, it was
recognized as a disadvantage that the shoe deformation of the material is excessive in the
carbonization step and the graphitization step of the synthetic resin, causing cracks and the like.
The present invention has such a point of curiosity and its object is to make the synthetic resin
carbonized or N-leaded sound It! (11) The sound quality is high in weight and rigidity, and the
ratio of Young's modulus to density is large, and the ratio of IC / IC is large. It is an object of the
present invention to provide a method for preventing the deformation of the material which
occurs in the step of graphitizing. Examples of the present invention will be described in detail
below. 20 parts of graphite powder, 30 parts of vinyl chloride resin, 10 parts of plasticizer (D, 0,
P), solvent (M, C) using lead-free powder with particle diameter of 5 to 100 J and vinyl chloride
resin as carbon powder and synthetic resin. K and K) 50 parts (both 1 菫) are thoroughly mixed
and kneaded, and molded with a formwork into a P9T desired shape (for example, a dome shape,
a cone shape, etc.) of the speaker diaphragm. The molded product is placed in a heating furnace
while being held by a mold so as not to be softened and deformed, and the temperature is raised
from room temperature to 300 ° C. for about 8 hours, and a nonoxidizing atmosphere such as
argon or nitrogen industry And carbonize at about 1000 ° C. for about 1 hour. The diaphragm
thus obtained has a very small deformation at carbonization and a density of 1. when compared
to one obtained by carbonizing only a synthetic resin without lead-free powder. s4j!
It is characterized by la & Young's modulus 16oOKp /-, and the regeneration frequency band is
broadened and distortion is reduced over that band compared with the conventional lifting plate
material, and excellent regeneration is made possible. Furthermore, when this diaphragm is
graphitized at 2400 ° C. for 5 minutes in an inert atmosphere while being held so as not to be
deformed by a graphite mold, the density is 1.8 fl / cd Young's modulus is 1800 Kp / md. It rose
and it became a diaphragm which has the outstanding characteristic. In the present invention, as
the synthetic resin, a resin having a high carbon yield regardless of a thermoplastic resin or a
thermosetting resin is desirable, and in addition to the vinyl chloride shown in the examples,
styrene, silicon, acrylic, phenol It is possible to use one or more mixtures of other synthetic resins
such as furan, urea, polyester and the like, and another carbon powder is carbon black. In
addition, various suitable plasticizers, bath agents and the like may be selected and used for the
resin, and the heat treatment conditions for carbonization or graphitization may be appropriately
adjusted depending on the mixed system of the resin, the plasticizer and the solvent. As
described above, according to the manufacturing method of the present invention, deformation
of the material that occurs when carbonizing or graphitizing a synthetic resin by heat treatment
is prevented, mass productivity is possible with high accuracy, and visibility is good. A diaphragm
for an acoustic device such as a dome-shaped or cone-shaped two-peaker, microphone can be
obtained. Also, since the powder used is a material made of carbon, it is possible to extremely
increase the heat treatment temperature in the graphitizing step, whereby Young's modulus IC or
ratio of Young's modulus to density E / ρ An extremely high diaphragm can be obtained. Patent
Applicant Pioneer Corporation EndPage: 2