JP2997685B2 - Speaker diaphragm - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a structure of a diaphragm of an electrodynamic loudspeaker.

[Prior Art] In the case of a diaphragm of an electro-dynamic type loudspeaker, for example, in the case of a cone-shaped diaphragm, as is well known, a local portion of the diaphragm is driven by a voice coil bonded near the center of the diaphragm, as is well known. When the driving frequency is increased, the movement of the part of the diaphragm away from the driving point is delayed with respect to the movement of the driven point, causing a so-called divided vibration, and interference due to a mutual phase shift in each part of the diaphragm. Caused the frequency characteristics to be disturbed.

In order to alleviate this drawback, the diaphragm of the electrodynamic type speaker is required to have as large a rigidity as possible and to have a large vibration absorption force for suppressing abnormal resonance of the diaphragm.

A typical structure of a conventional diaphragm is, for example, (1)
Molded from a single material such as pulp, metal, synthetic resin,
(2) a carbon fiber woven fabric or the like impregnated with a thermosetting resin and heat-molded; and (3) a carbon fiber woven fabric or the like and a thermoplastic synthetic resin sheet laminated and heated and formed. I have.

[Problem to be Solved] In the conventional diaphragm having such a structure, it is difficult for the diaphragm belonging to (1) to have both rigidity and vibration absorption force due to the nature of the material, and it belongs to (2). The diaphragm has low impact resistance, low water resistance, and low long-term stability because the fiber binder is a thermosetting resin. Furthermore, the molding cycle at the time of production is long, and the preservability of the prepreg as a molding material is not good.
Further, the diaphragm belonging to (3) has a problem to be solved in that, for example, when polypropylene resin is used as the thermoplastic synthetic resin sheet, drape at the time of molding is poor, and a high-pressure press is required.

Therefore, the present invention solves the problems of the above-described conventional example by using a composite of a liquid crystal polymer fiber and a thermoplastic synthetic resin fiber, and achieves a speaker vibration having both high rigidity and large internal loss. The purpose is to provide a board.

[Means for Solving the Problems] A diaphragm of a loudspeaker according to the present invention for achieving the above-mentioned object comprises a liquid crystal polymer fiber and a thermoplastic synthetic resin fiber, and the liquid crystal polymer fiber is A speaker diaphragm, which is bonded and compounded by thermoplastic synthetic resin fibers melted during heat molding.

[Operation] The liquid crystalline polymer fiber has a lower density (ρ), a higher cutting strength (1.5 to 2 times that of carbon fiber, etc.) and a lower melting point than a conventional composite material such as carbon fiber. It is thermally stable because of its high temperature of 300 ° C. or higher, and has a feature that the fiber itself has a large internal loss (tan δ) because it is a fiber having a fibril structure.

By combining liquid crystalline polymer fibers of such properties with molten thermoplastic synthetic resin fibers, the liquid crystalline polymer fibers are uniformly dispersed in the composite material, and the physical properties of the composite material are the same as those of conventional carbon fibers. Ρ is small and tan δ is large as compared with a composite material using the same.

Furthermore, since both fibers are thermoplastic synthetic resin fibers,
It has excellent impact resistance and storage stability, and can shorten the molding time. In addition, since it is excellent in drapability and wettability as compared with the conventional sheet-like thermoplastic synthetic resin composite, the quality is stable without voids.

[Example] A flat fiber cloth of wholly aromatic polyester fiber was used as the liquid crystalline polymer fiber, and a plain woven cloth of PP (polypropylene resin: glass transition temperature = 0 ° C, melting point 170 ° C) fiber was used as the thermoplastic synthetic resin fiber. Plain woven fabric of PP fiber is laminated on both sides of a plain woven fabric of wholly aromatic polyester fiber to make three layers, and the speaker is formed by press molding in a cone-shaped mold at a temperature of 140 ° C and a pressure of 6 kg / cm ² for 2 minutes. A diaphragm for use was obtained.

Table 1 shows values of tan δ, Young's modulus E, density ρ and E / ρ of the diaphragm at room temperature, and Table 2 shows molding conditions. For comparison, the above-mentioned physical properties and molding conditions of a conventional diaphragm obtained by laminating a carbon fiber woven fabric and a polypropylene sheet were also shown. From these results, the composite diaphragm of the present invention shows larger values for both E / ρ and tan δ as compared with the conventional example. In particular, as for the molding pressure, compared to the case of the conventional PP sheet composite, it can be formed by shifting the weave of the woven fabric, so it is easy to shape and shape, and the thermoplastic synthetic resin for bonding is a fiber, so it is easy to melt So the molding pressure is about 1 /
3 is sufficient, and the molding time is shortened.

As a means for obtaining the composite of the present invention, as a first modified example of the above embodiment, a woven fabric (combined weave, made of a long fiber strip (commingled yarn) blended with a liquid crystalline polymer fiber and a thermoplastic synthetic resin fiber) is used. (Triaxial weave, disc weave, etc.) in one or more layers. Further, as a second modification, a single layer or a plurality of layers of a woven fabric of a pride matrix in which the surface of a liquid crystalline polymer fiber is wrapped with a thermoplastic synthetic resin fiber may be formed. Alternatively, as a third modification, a means using a woven fabric in which two kinds of fibers are mixed and woven is conceivable.

As described above, the diaphragm of the speaker according to the present invention has been described in detail based on the example which is considered to be representative. However, the embodiment of the diaphragm according to the present invention is based on the structure of the above example in the material of the material resin. The present invention is not limited to the above, and may be appropriately modified and implemented as long as it has the components described in the above-described claims, exhibits the effects of the present invention, and has the effects described below.

[Effect] The diaphragm of the loudspeaker according to the present invention has a structure in which liquid crystal polymer fibers are fused and bonded with thermoplastic synthetic resin fibers, and the liquid crystal polymer fibers are formed of a conventional composite material such as carbon fiber. In comparison with, the density (ρ) is small, the cutting strength is high (1.5 to 2 times that of carbon fiber, etc.), and the melting point is as high as 300 ° C. or higher, so it is thermally stable and has a fibril structure. It is characterized in that the internal loss (tan δ) of the fiber itself is large.

By combining liquid crystalline polymer fibers of such properties with molten thermoplastic synthetic resin fibers, the liquid crystalline polymer fibers are uniformly dispersed in the composite material, and the physical properties of the composite material are the same as those of conventional carbon fibers. Ρ is small and tan δ is large as compared with a composite material using the same.

In addition, since the thermoplastic synthetic resin fiber is further used, it is excellent in impact resistance, water resistance, long-term stability and storage stability, and since two kinds of fibers are in a partially mixed state,
The molding time can be shortened. In addition, since it is excellent in drapability and wettability as compared with the conventional sheet-like thermoplastic synthetic resin composite, it has an effect that there is no void and the quality is stable.

Claims (2)

(57) [Claims] 1. A liquid crystal polymer fiber and a thermoplastic synthetic resin fiber, wherein the liquid crystal polymer fiber is bonded and compounded by a thermoplastic synthetic resin fiber melted during heat molding. A woven fabric made of long fibers obtained by mixing the liquid crystal polymer fiber and the thermoplastic synthetic resin fiber, a pride matrix woven fabric in which the surface of the liquid crystal polymer fiber is wrapped with the thermoplastic synthetic resin fiber, or A speaker diaphragm which is formed by heating and forming a woven fabric in which liquid crystalline polymer fibers and the thermoplastic synthetic resin fibers are woven together. 2. A diaphragm for a speaker according to claim 1, wherein said liquid crystalline polymer fiber is a copolyester of ethylene comprising parahydroxybenzoic acid and terephthalic acid, or a copolyester of phenylene or biphenylene. .