JPH0357400A - Diaphragm for speaker - Google Patents

Abstract

PURPOSE:To obtain a diaphragm with a large specific elastic rate, a proper internal loss and excellent characteristic by using a mixed woven cloth made of 3 kinds of specific single threads for one base of at least one skin member in a diaphragm for a speaker of 3 layer sandwich structure. CONSTITUTION:Surface skin members 3, 4 are applied to inside and outside of a core material 2 made of a honey-comb core made of an aluminum foil to form 3-layer sandwich structure. At least one of the surface skin members 3, 4 uses a woven cloth 8 subject to plain weave of a carbon fiber single thread 5, a single thread 6 of aromatic polyamide fiber and a single thread 7 of high tensile strength polyethylene fiber as a base and a resin is impregnated to the base, the base is cured by heating and pressing to obtain a fiber reinforced plastic. Thus, a diaphragm with a large specific elastic rate, a proper internal loss and excellent characteristic is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a speaker diaphragm, particularly to a speaker diaphragm having a sanderch structure with excellent frequency characteristics in the high range. (Prior Art) In general, the characteristics required of a speaker diaphragm include (a) a small areal density, and (b) a large specific elastic modulus E/ρ (where E: elastic modulus, ρ : density), (c) have a moderate internal loss tan δ, and (2) have high bending rigidity. In particular, in a cone-shaped diaphragm, the inner circumference (voice coil Ill) must faithfully propagate the vibrations of the voice coil bobbin, so a large specific modulus of elasticity is required. On the other hand, since the outer periphery (edge side) must absorb vibrations reflected from the edge, it is ideal that the internal loss be appropriately large.

Conventional speaker diaphragms have a three-layer sandwich structure in which a skin material made of a thin film of fiber-reinforced plastic 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 polymer material. There are things that I have. As a base material for the above-mentioned skin material, for example,
-43994 publication describes carbon fiber. A method using #I fiber made of glass fiber, aromatic polyamide fiber, etc. has been disclosed.

[Problem to be solved by the invention]

However, in conventional speaker diaphragms that have a three-layer sandwich structure of this type 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 elastic modulus. Although this structure is effective as a diaphragm, in general, the specific modulus of elasticity and internal loss are inversely proportional to each other, so it is difficult to reduce the internal loss and sufficiently satisfy the required characteristics as a diaphragm for a speaker. The problem was that it couldn't be done. In addition, the speaker diaphragm based on aromatic boriamite fiber is carbon! am or glass k
Although the internal loss is larger than that using I7A fiber as the base material, there is a problem in that the specific modulus of elasticity does not reach the ideal characteristic level.

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

(Means for Solving the Problem) Therefore, the speaker diaphragm according to the present invention has a three-counterfeit sandwich structure in which a skin material made of a fiber-reinforced plastic film is adhered to both sides of a core material made of a core material. In the speaker diaphragm having the following, the base material of at least one of the skin materials is a mixed jaIa obtained by interweaving three types of single yarns of carbon fiber, aromatic polyamide 1a#l, and high-tensile polyethylene fiber. By using cloth, this object is intended to be achieved.

[Effect]

When the speaker diaphragm of this invention is attached to a speaker frame, connected to a voice coil, and used in the same way as conventional ones, this speaker diaphragm has a high specific modulus of elasticity, so it faithfully reproduces the vibration of the voice coil bobbin. spreads to
In addition, since it has a moderate internal loss, it absorbs reflected vibrations from the edges, and there is little variation in frequency characteristics in the high frequency range.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

Figure 1 is a side cross-sectional view of a speaker diaphragm according to an embodiment of the present invention, Figure 2 is a plan view of the base material of this embodiment, and Figure 3 is taken along the line A-A in Figure 2. This is a clear illustration.

In Figure 1 of the drawing, 1 is a speaker diaphragm, which is formed into a cone shape, and each skin material 3.4 is adhered to the inside and outside of a core material 2 made of a honeycomb core of aluminum foil. to form a three-layer sandwich structure. Each skin material 3.4 has carbon I at least on one side.
A woven fabric 8 made of a plain weave of a single yarn 5 of Im miscellaneous, a single yarn 6 of aromatic polyamide fiber, and a single yarn 7 of high-tensile polyethylene MIm is used as a base material, impregnated with a resin, and heated. It is made into fiber-reinforced plastic by hardening it under pressure. Next, a method of manufacturing the speaker diaphragm of this embodiment will be explained with reference to FIG.

In FIG. 2, a single yarn 5 made of carbon fiber with a diameter of 7 μm is placed on the vertical axis, and then a single yarn 6 made of aromatic polyamide fiber is placed on the vertical axis.
Then, the single yarns 7 of high tensile strength polyethylene fibers are arranged side by side, and the carbon fibers are arranged again, which are repeated.

Also, do the same as above for the horizontal axis. The wheel yarns 5, 6, and 7 are woven together to form a mixed rope cloth 8. Then, this woven fabric 8 is impregnated with epoxy resin and heated and cured while being pressed, so that the volume content of the 5 fibers is approximately 50% and the thickness is 0.12 m.
m skin materials 3 and 4 are obtained. On the other hand, the core material 2 has a thickness of 0.05
Made of sm aluminum foil, cell size 3/16i
nch, using an aluminum honeycomb core with a thickness of 3 cm,
The skin materials 3.4 were attached to both sides of the core material 2 using an adhesive made of epoxy resin, and were adhered by heating and pressing to obtain a speaker diaphragm having a three-layer sandwich structure.

Below, the test results of the speaker diaphragm of this example will be explained. Table 1 shows the values of the specific elastic modulus E/ρ and internal loss tanδ determined by the vibration reed method for the specimens obtained by the above manufacturing method.

Table 1 also shows, as comparative examples, the results of a three-layer sandwich board based on a woven fabric made of carbon fiber and glass fiber roving, and a conventional paper cone.

Table 1 As is clear from Table 1, when the skin material of this example is made of mixed & i-silk T5C, which is made by interweaving three-pole single yarns of carbon fine fiber, aromatic polyamide fiber, and high-tensile polyethylene fiber, The specific elastic modulus is almost the same as that of conventional glass fiber, and the internal H] loss is about the same as that of a conventional paper cone, and the piston movement area is approximately twice as large as that of a conventional paper cone diaphragm. Moreover, due to the large internal loss, there is little fluctuation in the frequency response in the high 11 range, and the characteristic sound peculiar to the honeycomb diaphragm disappears, resulting in a speaker diaphragm with a three-layer sandwich structure that is extremely effective in terms of physical properties and auditory characteristics. I know that it will happen.

The core material used as the core material is metal (aluminum in the example) or high-grade material.
A core material such as a honeycomb core consisting of a honeycomb core can be used, and a honeycomb core made of a honeycomb core with a part thereof cut out to increase the curvature may also be used. 8 single yarn C) straight {straight 7μ
m, but the f+ range is preferably 7 to 10 μm.

In addition, the weaving method uses each m thread as the vertical axis. It is 1' or 1,1 to arrange and incorporate them in order on the horizontal axis.

In this way, it is preferable to weave three types of IJ yarns in order to form a mixed woven fabric and use this as the skin material, but after weaving two or three of the same fibers together, other fibers are You may also use something that is woven in instead of .

As mentioned above, when such a rope cloth is used as the base material of one skin material, conventional carbon fiber is used as the base material of the other skin material.
Using woven fabrics such as aromatic polyamide Ml fibers and glass fibers,
These base materials are impregnated with resin such as epoxy resin, heated and pressurized to harden the resin to form fiber-reinforced plastics, and form skin materials. Then, this skin material can be stacked on both sides of the core material and bonded to form a sandwich structure, thereby producing a vibration plate for vibration and force.

〔Effect of the invention〕

As explained above, according to the present invention, carbon fibers, aromatic polyamide fibers, and high tensile strength polyethylene fibers are
! Since the blended JIJIm fabric, which is made by interweaving single yarns of
This has the effect of providing a speaker diaphragm with excellent frequency characteristics in the treble range.

[Brief explanation of drawings]

FIG. 1 is a side sectional view of a speaker diaphragm according to an embodiment of the present invention, FIG. 2 is a plan view of a base material of this embodiment, and FIG. 3 is an A-Alli plane view of FIG. 2. . 1...Speaker diaphragm 2...Single core material 3.4...Skin material 5...Carbon fiber υ thread 6...Aromatic Boamito embroidery M single thread 7...
・High tensile strength polyethylene embroidery miscellaneous single thread 8... Rope cloth In the drawings, the same reference numerals refer to the same or corresponding parts.

Claims (1)

[Claims] In a speaker diaphragm having a three-layer sandwich structure in which a skin material made of a thin film of fiber-reinforced plastic is bonded to both sides of a core material made of a core material, at least one of the skin materials has carbon fiber and an aromatic A diaphragm for a speaker characterized by using a mixed woven fabric made by interweaving three types of single yarns of polyamide fiber and high-tensile polyethylene fiber.