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明 all 扮 1, the title of the invention
Method of manufacturing speaker diaphragm
3. Detailed Description of the Invention The present invention relates to a method of
manufacturing a speaker diaphragm. In order to reproduce faithful sound in the speaker, it is
desirable that the vibration of the diaphragm, which is the vibrating body of the speaker, perform
piston movement over as wide a range as possible. For this purpose, it is advantageous for the
diaphragm to be light and rigid. That is, assuming that Young's modulus E and activity P, the
larger $ is better. In the past, with this point in mind, many attempts have been made to increase
carbon fiber that exhibits high elasticity by mixing it with natural or synthetic fibers to increase
the thickness of the diaphragm 4). At that time, the drop in the output sound pressure level could
not be removed. This is because, even if highly elastic carbon fibers are employed, the
propagation speed of vibration between high elastic fibers is limited due to the lack of bonding
between the fibers. The present invention has been made in view of these points, and it is a
process of forming a diaphragm substrate using a carbon fiber as a main material and using a
polymer binder, carbonizing the substrate, and forming a carbonized substrate. The present
invention provides a method of manufacturing a speaker diaphragm including the step of plating.
According to the present invention, since carbon fibers are bonded by metal by plating, g! The
bond strength between the fibers is increased, and the acoustic characteristics of the diaphragm
can be improved. Also, at this time, bonding the fibers with gold 4 means that the metal has a
very high Young's modulus, so appropriately suppressing the precipitation basin of the metal due
to plating makes it possible to improve the speaker characteristics better than K. It is excellent at
the point which can be achieved. Also, as in the present invention, bonding between the fibers by
chemical plating is different from that by electroplating, because the surface tension effect by use
of an appropriate surface-active agent EndPage: The narrow part between the fibers Also, it is
excellent in that the plating solution penetrates and the metal can be uniformly deposited
between the fibers. That is, excessive metal deposition can be suppressed to prevent an increase
in density ρ. Furthermore, as in the present invention, if the diaphragm substrate is molded with
a polymeric binder prior to the chemical plating step, and then the substrate is carbonized, the
binder that bonds the fibers is carbonized, Not only does the binder itself increase its elasticity to
contribute to the improvement of acoustic characteristics, but it also improves the heat
resistance, water resistance, chemical resistance, etc. of the binder. In the case where the
diaphragm substrate is immersed, the diaphragm substrate does not slip by the mold X, and
metal deposition is also ensured. In the present invention, the amount of metal deposition by
chemical plating is preferably less than 20% of the vibrational basis weight, and more (if it is
deposited, it only causes an increase in the density, and the floss decreases rather.
In the present invention, electroless plating, silver mirror reaction, etc. are adopted as the
chemical plating treatment, and as the plating metal, a metal of specific elasticity such as nickel,
chromium, tungsten etc. is preferable. In the present invention, as the polymer binder, resins of
phenol type, acrylic type and rayon type are preferable, and these are sublimed in carbonization
and the female yield is high after carbonization. The present invention will be described below.
First, 80 parts of carbon fiber with an elastic modulus of 500% / mm 2 to 15,000 exposed 2 is
cut into 3 wn to about 10 cabinets, and 20 parts of 11 beaten pulp is blended with this to form a
sheet, and it is formed into a cone A diaphragm substrate was obtained, and this substrate was
immersed in a methanol solution to which 50 g of a phenol formaldehyde resin was added as a
polymer binder and then heat cured to obtain the above-mentioned diaphragm substrate as a
reliable molded body. The temperature of the obtained diaphragm substrate was gradually raised
in a nitrogen atmosphere, and at 1000 ° C., carbon was added to form the carbide of the
vibrator / plate substrate, and then the pretreatment was performed according to the usual
method. After that, electroless nickel plating is performed by immersing the above-mentioned
diaphragm substrate in a plating solution at 60 ° C. for 4 minutes, and nickel is added via the
carbide of the binder between the fiber surface and fibers constituting the diaphragm. It was
precipitated to enhance the bonding between fibers. At this time, the precipitation of nickel was
about 15% of the weight of the diaphragm substrate. The density of the diaphragm thus obtained
is p: 0.25 // cm '. The sound speed was 5 = 2.7 and the frequency characteristic was as shown in
A of the figure, and the output sound pressure level showed no drop to around 18 KHz. B in the
figure shows the frequency characteristics of a conventional diaphragm which is obtained by
mixing 10 pieces of carbon fiber and 90 pieces of pulp and is not subjected to carbonization or
plating as in the present invention, and in this case, the output sound The pressure level shows a
drop without reaching 10 KH2. After impregnating the diaphragm manufactured in the above
example with a resin solution mixed with a foaming agent, heat expansion is performed to give a
suitable internal S loss to the high elastic vibration plate material, and divided vibration in a high
frequency region It is possible to suppress and improve the durability. As is apparent from the
above description, according to the present invention, carbon fiber having high elasticity can be
used as a diaphragm for a speaker to sufficiently utilize its characteristics and quality, and the
improvement of the sound O characteristic of the speaker can be largely achieved. be able to.
4. A simple explanatory diagram of the drawings is a curve diagram showing acoustic
characteristics of the speaker diaphragm. Patent applicant Sanyo Electric Co., Ltd. representative
稙 薫, '· EndPage: 2