JPH02192299A - Diaphragm for speaker - Google Patents

Abstract

PURPOSE:To improve frequency characteristic at a high frequency range by using a blend fiber cloth made of carbon fibers applied with brass plating and aromatic polyamide fibers not applied with plating as the substrate of a skin member. CONSTITUTION:Skin members 3, 4 are formed by using a roving 5 being an aggregate of monofilaments being carbon fibers subjected to brass plating or tint plating (at least one of the members 3, 4) and flat woven cloth 6 of aromatic polyamide not applied with plating as the substrate, impregnating resin, curing the resin by hating/pressing as a fiber reinforced plastic. Since the diaphragm for speaker has a high specific elastic modulus, the vibration of a voice coil bobbin is propagated with fidelity and proper internal loss is provided. Thus, the reflected vibration from the edge is absorbed and the frequency characteristic at the high frequency range is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a diaphragm for a speaker, and particularly to a diaphragm for a speaker having a sandwich structure with excellent frequency characteristics in the treble range.

(Prior art) In general, the characteristics required for a speaker diaphragm include (a) a small areal density, and (b) a large specific modulus of elasticity E/ρ (here, E: l/ll property). ratio, ρ: density 1, (c) moderate internal loss tan δ, (d) high bending rigidity, etc.Especially for cone-shaped diaphragms,
Since the inner peripheral portion (voice coil side) must faithfully propagate the vibrations of the voice coil bobbin, a large specific modulus of elasticity is required. On the other hand, since the outer periphery (edge side) must absorb vibrations reflected from the edges, it is ideal that the internal loss be appropriately large.

As a conventional speaker diaphragm, a three-layer sandwich is used as a diaphragm in which a skin material made of fiber-reinforced plastic G membrane is bonded to both sides of a core material made of a core material such as a honeycomb core made of a thin film of metal or polymeric material. Some have a structure. Carbon fiber, glass i
It has been proposed to use woven fabrics made of am, aromatic polyamide fibers, etc.
Publications, etc.).

[Problem to be solved by the invention]

However, in conventional speaker diaphragms that have this type of three-layer sandwich structure using carbon fiber or glass fiber as a base material, since the base material has a high elastic modulus, the sandwich structure also has a high specific modulus of elasticity, and the diaphragm Although it is an effective structure, numerically speaking, the specific elastic modulus and internal loss are in an inversely proportional relationship, so the internal loss is small enough to meet the required characteristics as a speaker diaphragm. could not. Furthermore, speaker diaphragms based on aromatic polyamide fibers have higher internal loss than those based on carbon fibers or glass fibers, but the specific modulus of elasticity does not reach the ideal characteristic level. There was a problem.

This invention was made in order to solve the problems of the conventional example as described above, and has a large specific modulus of elasticity, moderate internal loss, and satisfies the characteristics required for a speaker diaphragm. Our first objective is to provide a diaphragm for speakers.

(Means for solving JIi) For this reason, the speaker diaphragm according to the present invention has a three-layer sandwich structure in which skin materials made of thin films of fiber reinforced plastic are bonded to both sides of a core material made of a core material. In a speaker diaphragm having a diaphragm, a mixed fiber fabric consisting of carbon fibers plated with brass or tinned and aromatic polyamide fibers without plating is used as the base material of at least one of the skin materials. By doing so, we aim to achieve the 111th purpose.

[Effect]

With the above configuration, the speaker diaphragm according to the present invention obtained is attached to a speaker frame, connected to a voice coil, and used in the same manner as a conventional one.This speaker diaphragm has a specific elastic modulus. Because of its high frequency, it faithfully propagates the vibrations of the voice coil bobbin, and because it has a moderate internal loss, it absorbs reflected vibrations from the edges, reducing frequency response fluctuations in the high frequency range.

〔Example〕

The present invention will be explained below based on examples.

(Structure) Fig. 1 is a sectional view showing an embodiment of a speaker diaphragm according to the present invention, Fig. 2 is a plan view of its base material, and Fig. 3 is a cross section taken along line AA in Fig. Show the diagram.

In FIG. 1, reference numeral 1 denotes a speaker diaphragm, which is formed into a cone shape and has skin materials 3.4 bonded to the inside and outside of a core material 2 consisting of a honeycomb core made of aluminum foil. It forms a layer sandwich structure. Each of the skin materials 3 and 4 includes a roving 5, at least one of which is an aggregate of single yarns made of carbon fiber plated with brass or tin, and a woven fabric 6 made of a plain weave of unplated aromatic polyamide. is used as a base material, impregnated with resin and heated/
It is made into fiber-reinforced plastic by hardening under pressure.

In this case, as the core material that becomes the core material 2, as mentioned above, a core material such as a honeycomb core made of a thin film of metal such as aluminum or polymer material can be used, and a part of it is cut out to increase flexibility. It is also possible to have a structure in which the The woven fabric that serves as the base material for one or both of the skin materials adhered to both surfaces of the core material is a blend of carbon fibers plated with brass or tin, and aromatic polyamide fibers without plating. It is composed of cloth.

The thickness of the plating layer is preferably about 0.05 to 0.5 μm. Plating is performed with the spacing between single Ml fibers maintained on the carbon fiber single fibers or rovings,
It is preferable that the plating layer be formed uniformly on the entire surface of each single fiber.

It is preferable to use the brass-plated or tin-plated carbon fiber as a base material for the skin material by forming a woven fabric such as a plain weave with aromatic polyamide from the roving, but it is preferable to use the roving as a base material for the skin material. may be formed. When such a woven fabric is used as the base material for only one skin material, the base material for the other skin material may be conventional carbon fiber, aromatic polyamide fiber,
Use silk cloth such as glass fiber. These base materials are impregnated with a resin such as an epoxy resin, heated and pressurized to harden the resin to form a fiber-reinforced plastic, and form a skin material. Then, this skin material is layered on both sides of the core material and bonded to form a sandwich structure, thereby obtaining a speaker diaphragm.

(Prototype example and its characteristic values) Here, a roving made of carbon m fibers with a diameter of 7 μm is plated with a 0.1 μm thick nickel base plating, and further plated with 0.1 μm of brass plating or tin plating. 1 Form a woven fabric by plain weaving aromatic polyamide, impregnate it with epoxy resin, heat harden it while pressing, and make each skin material 3 with a fiber volume content of about 50% and a thickness of 0.12 mm. I got .4. As the core material 2, an aluminum honeycomb core made of aluminum foil with a thickness of 0.05 mm and a cell size of 3/16' and a thickness of 3 m11 was used. In addition, each of the above-mentioned skin materials 3 and 4 was pasted on both sides of the core material 2 using an adhesive made of epoxy resin 1, and adhered by heating/pressure to obtain a prototype speaker diaphragm with a three-layer sandwich structure. . The specific elasticity of the obtained specimen was determined by the vibration lead method: 4! E/ρ and internal loss tanδ
The values are shown in Table 1.

As comparative examples, Table 1 also shows the results of three-layer sandwich boards 5 each using a woven fabric made of carbon fiber and glass fiber roving as a base material and a conventional paper cone.

Table 1 As is clear from Table 1, when the skin material is made of a mixed &1ik E/ρ is almost the same value as that of conventional glass fiber, and the internal loss ta
nδ is the same value as a conventional paper cone, and the piston movement area can be expanded to about twice that of a conventional paper cone diaphragm.
Moreover, because the internal loss is large, the frequency characteristics in the high frequency range are less distorted, and the unique sound peculiar to the honeycomb diaphragm disappears.
It can be seen that a speaker diaphragm having a three-layer sandwich structure that is extremely effective in terms of physical properties and auditory characteristics can be obtained.

(Effects of the Invention) As explained above, according to the present invention, a silk cloth made of IA roving plated with brass or tin plated and aromatic polyamide without plating is used as the base material of the diaphragm. A speaker diaphragm having a large specific modulus of elasticity, moderate internal loss, and excellent frequency characteristics in the high frequency range was obtained.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of one embodiment of a speaker diaphragm of the present invention, FIG. 2 is a plan view of its base material, and FIG. 3 is a cross-sectional view taken along the line AA in FIG. 2. In each figure, the same reference numerals indicate the same or equivalent components, 1
is the speaker diaphragm, 2 is the core material, 3.4 is each skin material,
5 is a roving, and 6 is a woven fabric.

Claims (2)

[Claims] (1) In a speaker diaphragm having a three-layer sandwich structure in which skin materials made of thin films of fiber-reinforced plastic are bonded to both sides of a core material made of a core material, at least one of the skin materials is plated with brass as a base material. A diaphragm for a speaker, characterized in that it uses a mixed woven fabric made of carbon fibers coated with plating and aromatic polyamide fibers that are not plated. (2) In a speaker diaphragm having a three-layer sandwich structure in which skin materials made of thin films of fiber-reinforced plastic are bonded to both sides of a core material made of a core material, at least one of the skin materials has tin plating as a base material. A diaphragm for a speaker, characterized in that it uses a mixed woven fabric made of carbon fibers coated with plating and aromatic polyamide fibers that are not plated.