JPS6359638B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a diaphragm in an electroacoustic transducer such as a speaker, and more specifically, it is capable of obtaining uniform vibration characteristics in a wide band, and improves durability and reliability. The present invention relates to a diaphragm and a method for manufacturing the same.

In general, the frequency band of an electroacoustic transducer such as a speaker is determined mainly by the material of the diaphragm. elastic modulus, ρ is density, I is moment of inertia) is large, and internal loss tan δ
A diaphragm material with a suitably large value is required.
In other words, the larger the specific longitudinal elasticity E/ρ, the higher the treble limit frequency (fh), which expands both areas of piston motion, thereby broadening the frequency band of the speaker, and the larger the bending stiffness E/I, the lower the distortion. Furthermore, if the internal loss tan δ is appropriately large, the Q value of the diaphragm is appropriately reduced, making it difficult for split resonance to occur, making it possible to flatten the characteristics (no coloration in the reproduced sound). In addition, especially when designing acoustic diaphragms,
Since it is necessary to reproduce transient waveforms containing high frequency components (which corresponds to most musical sounds), wideband characteristics are required. For this reason, material selection is a major issue, and recently, diaphragms made of beryllium, which has a higher specific longitudinal elastic modulus E/ρ than aluminum alloys and titanium alloys, have been put into practical use. ing.

However, beryllium is a very expensive material and has brittle properties, resulting in poor workability and high cost.
Therefore, recently, composite materials have been used which are composed of reinforcing fibers having a high modulus of longitudinal elasticity and a matrix material that binds these fibers.
Compared to the conventional light alloys mentioned above, such composite materials have a larger longitudinal elastic modulus E and a smaller density ρ, so they have a larger specific longitudinal elastic modulus E/ρ and can provide broadband frequency characteristics. Moreover, it has excellent characteristics in terms of being easy to manufacture and inexpensive, but conventionally reinforcing fibers with a high longitudinal modulus are arranged in the direction of arrow A as shown in Figure 1 a and b. The single flat sheet 1 formed by the process is cut in accordance with the developed view of the dome-shaped diaphragm so that the fiber direction and the bottom circumference of the dome are perpendicular to each other, and the fibers are joined at the cut points. Since the dome-shaped diaphragm 2 is formed by joining with a matrix material,
The bonding degree of the joint portion 3 is weak, and it is easy to separate during high-output vibration, resulting in a lack of durability and reliability.

This invention was made in view of the above-mentioned points, and is characterized by the fact that multiple composite sheets are laminated and bonded together, resulting in high strength, durability, and reliability. The present invention provides a diaphragm for an electroacoustic transducer and a method for manufacturing the same, which can improve performance and obtain uniform vibration characteristics over a wide band.

Therefore, the first object of the present invention is to divide the sheets of each layer when laminating a plurality of composite sheets made of reinforcing fibers having a high modulus of elasticity and a matrix material that binds these fibers. It is composed of a plurality of formed sheet pieces, and is laminated in a positional relationship rotated by a predetermined angle with sheets of adjacent other layers, so that the joint of each sheet piece overlaps with the sheet pieces of adjacent sheets of other layers. Our goal is to provide a diaphragm with a high quality.

A second object of the present invention is to form a prepreg by arranging reinforcing fibers having a high modulus of longitudinal elasticity in the same direction and bonding these fibers with a matrix material, and to form a prepreg by arranging reinforcing fibers having a high modulus of longitudinal elasticity in the same direction. The prepreg pieces are divided into substantially identical prepreg pieces, and these prepreg pieces are stacked so that adjacent prepreg pieces in the left and right directions are close to or in contact with each other, and adjacent prepreg pieces in the thickness direction partially overlap. An object of the present invention is to provide a method for manufacturing a diaphragm in an electroacoustic transducer, in which a plurality of layers are heated and pressurized to be integrally bonded.

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.

FIG. 2 is a front view showing an embodiment in which the present invention is applied to a cone-shaped diaphragm, and FIG.
FIG. 4 is an enlarged sectional view taken along the line of FIG. 2 and expanded to its original flat state. In these figures, the cone-shaped diaphragm 1
0 is formed into a predetermined cone shape by two composite sheets 11 and 12 made of the same material stacked and arranged, and a neck part 13 is integrally connected to the open end on the base side. A bobbin (not shown) around which a voice coil is wound is connected and fixed to 13.

Each composite material sheet 11, 12 is divided approximately equally in the circumferential direction, for example, into six sheet pieces 11A~
11F and 12A to 12F. Therefore, each of the sheet pieces 11A to 11F and 12A to 12F is a composite material sheet 11,
In the developed view of No. 12, it has a substantially trapezoidal shape, and the side edges of adjacent sheet pieces are joined to each other. In this case, the inner composite sheet 11 and the outer composite sheet 12 are laminated while being rotated approximately 30 degrees, so that the joints 14 of the inner sheet pieces 11A to 11F are connected to the outer sheet pieces 12A to 12F. located almost in the center of Therefore, the joint portions 15 of the outer sheet pieces 12A to 12F are also located approximately at the center of the inner sheet pieces 11A to 11F. In this state, all the sheet pieces 11A~
The cone-shaped diaphragm 10 is obtained by integrally bonding 11F and 12A to 12F by heating and pressurizing (described later), and as a result, the inner sheet piece 1
The joint portions 14 of 1A to 11F are the outer sheet pieces 12
A to 12F are reinforced, and joint portions 15 of the outer sheet pieces 12A to 12F are similarly reinforced by the inner sheet pieces 11A to 11F.

As shown in FIG. 4, the composite sheets 11 and 12 are made of a large number of carbon fibers 16 having a high modulus of longitudinal elasticity and whose fiber directions are aligned in one direction, an epoxy resin, and a phenol. and a matrix material 17 which is made of a thermosetting resin material such as resin or unsaturated polyester resin and which integrally binds the carbon fibers 16. When manufacturing the cone-shaped diaphragm 10, the fifth
As shown in the figure, carbon fibers 16 arranged in one direction (direction of arrow A) are impregnated with epoxy resin as a matrix material in a B stage (semi-cured) state.
A plurality of trapezoidal sheets having the same shape are obtained by cutting the sheets (prepreg) 20 of 20 in accordance with a development view of a predetermined cone-shaped diaphragm 10 so that the radial direction of the diaphragm itself and the direction of the fibers are in the same direction. Prepreg piece 2
1a to 21n are obtained. These cut prepreg pieces 21a to 21l are pasted on the circumferential surface of 22A to the truncated conical part of the male mold 22 as shown in FIG. 6, which is formed to correspond to the shape of the diaphragm 10 to be formed. It will be done. In this case, since the prepreg pieces 21a to 21l constitute the composite sheets 11 and 12 described above after molding, the surfaces of the first layer prepreg pieces 21a to 21f stuck on the surface of the truncated conical part 22A are The second layer prepreg piece 21g ~ 21l is approximately
It will be pasted with a 30 degree shift in the circumferential direction. Next, the female mold 23 is superimposed on the male mold 22, and pressure molding is performed while heating at about 150 degrees. By this heating and pressurization, each prepreg piece 21a to 21l
The matrix material is thermoset to bond the fibers together, and at the same time, all the prepreg pieces 21a to 21l are integrally bonded.

After thermosetting the matrix material, the molded product taken out from between the two molds 22 and 23 has its outermost cone edge 24 cut to a predetermined outer diameter and the cone neck 13 cut to a predetermined diameter, as shown in FIG. By cutting the fibers into lengths, a cone-shaped diaphragm 10 having a laminated structure made of a composite material of reinforcing fibers of carbon fibers 16 whose fibers are arranged in the radial direction and a matrix material of epoxy resin is constructed.

Although the above description has been made regarding the case where the present invention is applied to the cone-shaped diaphragm 10, the present invention is not limited to this, and can be applied to the center cap of a dome-shaped diaphragm or a cone-shaped diaphragm as it is. Of course. That is, FIG. 8a is a plan view when the present invention is applied to a dome-shaped diaphragm 30, and FIG. 8b is a sectional view taken along the line in FIG. 8a. In these figures, the dome-shaped diaphragm 30 is composed of an outer composite sheet 31 and an inner composite sheet 32, as in the case of the cone-shaped diaphragm 10 described above. The outer sheet pieces 31A to 31F and the inner sheet pieces 32A to 32F are arranged so that the joints of the inner sheet pieces do not overlap with the joints of the outer sheet pieces, and the joints of the outer sheet pieces overlap the inner sheet pieces. They are laminated and molded in a state where they are rotated approximately 30 degrees in the circumferential direction so that they do not overlap at each joint.

Further, in the above embodiment, two composite material sheets 11,
Although 12 sheets are stacked, the arrangement is not limited thereto, and three or four sheets may be stacked.

Furthermore, although carbon fiber 16 was used as the reinforcing fiber in the above example, it is also possible to use high modulus fibers such as glass fiber, graphite fiber, boron fiber, aramid fiber, silicon carbide fiber, and aromatic polyamide fiber. It is.

As described above, the diaphragm in an electroacoustic transducer according to the present invention and the method for manufacturing the same include a plurality of composite sheets formed by combining a plurality of sheet pieces each having a shape in which the diaphragm is divided around its central axis. When a diaphragm is formed by laminating and integrally bonding, the joints of each sheet piece are configured so that they do not overlap with the joints of adjacent sheet pieces of other composite sheets, so that the It has great strength, and this joint will not separate even when subjected to high-output vibrations, improving durability and reliability. In addition, because the composite sheet is composed of fibers with a high longitudinal modulus and a matrix material that integrally binds these fibers, it is lighter and has a lower specific longitudinal modulus than conventional light alloy diaphragms. It has a large E/ρ, a moderate internal loss, good vibration characteristics, and is easy and inexpensive to manufacture, making it very effective.

[Brief explanation of the drawing]

Figures 1a and b are a perspective view and a developed view of a dome-shaped diaphragm made of a conventional composite material;
The figure is a front view showing an embodiment in which the present invention is applied to a cone-shaped diaphragm, FIG. 3 is a sectional view taken along the line of FIG. 2, and FIG. Figure 5 is an enlarged cross-sectional view of the sheet expanded in a state where the fibers are arranged in one direction.
The figure is a diagram for explaining the forming of a diaphragm, FIG. 7 is a diagram for explaining the cutting of the end of a molded product, and FIGS. FIG. 2 is a plan view and a cross-sectional view taken along the line -1 of the embodiment. 10, 30... diaphragm, 11, 12, 31, 3
2...Composite material sheet, 11A~11F, 12A~
12F, 31A to 31F, 32A to 32F... Sheet piece, 14, 15... Joint part, 16... Carbon fiber, 17... Matrix material, 20... Sheet (prepreg), 21a to 21l... Prepreg piece,
22...male mold, 23...female mold, A...fiber direction.

Claims (1)

[Claims] 1. Formed by laminating and integrally bonding a plurality of composite sheets made of reinforcing fibers having a high modulus of longitudinal elasticity and a matrix material that binds these fibers. It is a diaphragm, and each composite sheet is composed of a plurality of sheet pieces divided around the central axis of the diaphragm and adjacent sheets are joined to each other, and is formed at a predetermined angle with other adjacent composite sheets. By stacking them in a rotated position,
A diaphragm in an electroacoustic transducer, characterized in that a joint portion of each of the sheet pieces is superimposed on an adjacent sheet piece of another composite sheet. 2. A diaphragm in an electroacoustic transducer according to claim 1, wherein the reinforcing fibers of each composite sheet are arranged in a radial direction with respect to the vibration direction of the diaphragm. 3. Reinforcing fibers having a high modulus of longitudinal elasticity are arranged along the same direction, these fibers are bonded by a matrix material to form a prepreg, and this prepreg is divided into prepreg pieces having approximately the same shape. The prepreg pieces that are adjacent in the left and right direction are placed close to each other or in contact with each other, and the adjacent prepreg pieces in the thickness direction are stacked so as to partially overlap with each other to form a plurality of layers, and these multiple layers By applying heat and pressure to harden the
Manufacture of a diaphragm for an electroacoustic transducer characterized in that adjacent prepreg pieces of each layer are bonded to each other, and at the same time, prepreg pieces adjacent in the thickness direction are overlapped with each other to bond all the prepreg pieces together. Method.