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FIELD OF THE INVENTION The present invention relates to a diaphragm used for a speaker.
[Prior Art] A speaker diaphragm is required to be evanescently as a characteristic, to have a large
Young's modulus, to have an appropriately large internal loss, and the like. Fats and metals can
be mentioned. Since these substrates alone have disadvantages, they are often used as a mixture
or composite with other materials. For example, some paper diaphragms are made by mixing
glass fiber or collagen into pulp for paper making to improve heat resistance and 114 humidity,
or mixing carbon an to improve Young's modulus and heat resistance. . In addition, a diaphragm
made of composite material reinforced with a 帷 is also known. For example, glass fiber Kepler
fiber (aromatic polyamide lI fiber). A diaphragm in which resin is reinforced with a woven fabric
such as carbon fiber has been developed. As the fibers, those having high elasticity such as the
above-mentioned glass fibers, Kepler fibers, carbon fibers and the like are used. Also, recently,
there is a mixed fiber of carbon fiber and glass fiber, or carbon fiber and Kevlar fiber. The resin
to be reinforced is a thermosetting resin such as unsaturated polyester resin or epoxy resin.
[Problem to be Solved by the Invention J Since the conventional I-fiber reinforced diaphragm is
formed as described above, the physical properties of the resin to be reinforced limit the
improvement of the physical properties as a diaphragm after heat curing. It has the disadvantage
of The present invention was made to eliminate the disadvantages of the prior art as described
above, and to provide a more rigid diaphragm by dispersing needle crystals (whiskers) in a
reinforced resin. The purpose is. [Means for Solving the Problems] Hereinafter, an embodiment of
the present invention will be described with reference to the drawings. FIGS. 2 and 3 are
schematic views showing an embodiment of the diaphragm of the present invention, FIG. 1 is a
plan view, and FIG. 2 is a front view. FIG. 3 is an enlarged cross-sectional view of FIG. 2A, in
which 1 is a high elastic lJi fiber, 2 is a resin for fiber reinforcement, and 3 is a nail-like crystal.
Incidentally, the reason that the cross section of the high elastic fiber of 1 is a dull circle is that it
spreads in the resin of 2 due to the press pressure at the time of heat molding. Next, the action of
the present invention will be described in the case where the high elastic 1ili fiber of 1 is a
carbon fiber having 3000 PAN filaments, the fiber reinforcing resin of 2 is an epoxy resin, and
the needle crystals of 3 are silicon nitride whiskers. . First, the carbon fiber 1 is a warp yarn and
a weft yarn, which are, for example, plain weaves.
Next, the plain weave carbon fiber is made into a prepreg by the following method. (1)
Impregnate in an epoxy resin liquid in which silicon nitride whiskers are dispersed. (Ii) Apply an
epoxy resin solution in which silicon nitride whiskers are dispersed by spray or the like. In
addition, 10 wt% of silicon nitride-containing gold in the epoxy resin was used. Next, the carbon
fiber woven into prepreg is set in the molding die 4 of FIG. 4 and pressurized and heated to cure
the resin. The molding conditions are as follows: the fabric is set in a mold preheated to about
120 ° C., preheated for about 2 to 3 minutes, and then pressurized and heated for about 20
minutes under a pressure of about 6 to 8 Kg / cm. Finally, the molded product is taken out of the
molding die, and when the inner and outer shapes are finished, a diaphragm as shown in FIGS. 1
and 2 is obtained. In this example, a speaker diaphragm was made by overlapping three sheets of
plain weave carbon fiber (number of PAN type filament 3000) at an angle of 60 ° with respect
to the fold direction, but the physical properties of the diaphragm were needle crystals. The table
below shows the comparison with the non-dispersed ones. As shown in the above table, the
density is slightly increased by dispersing the whiskers, but the Young's modulus is increased by
about 10% and the speed of sound is also increased. [Effects of the Invention] As described
above, according to the present invention, weight reduction is achieved by using a material in
which needle crystals (whiskers) are dispersed in a thermosetting resin that strengthens a woven
fabric of high elastic fibers. The high rigidity can be achieved, the piston movement is possible to
the high range as the speaker, the high frequency division vibration frequency can be raised, the
frequency characteristic in the audio frequency band can be flattened, and the efficiency of the
speaker can be improved. To contribute.
Brief description of the drawings
1 and 2 are schematic views showing an embodiment of the diaphragm of the present invention,
FIG. 1 is a plan view, and FIG. 2 is a front view.
FIG. 3 is an enlarged cross-sectional view of FIG. 2A. FIG. 4 is a schematic view of a mold in
diaphragm forming. 1 ......... high modulus fibers 2 ......... thermosetting resin 3 ......... needles