JPS58220598A - Diaphragm for electric acoustic transducer and its production - Google Patents

Abstract

PURPOSE:To improve the strength, durability and reliability and to realize the uniform oscillation characteristics in a wide band, by laminating plural composite material sheets, and by combining them in one body. CONSTITUTION:A cone like diaphragm 10 is formed with laminated composite material sheets 11 and 12, and a neck part 13 is incorporated at the end of an opening. The sheets 11 and 12 are composed of sheet pieces 11A-11F and 12A- 12F divided almost equally in circular direction, and side edges of adjacent sheet pieces are connected to each other. Internal and external sheet pieces are mutually turned by about 30 deg. and laminated. The connected part is located in the center of other sheet piece each other. Each sheet piece is heated, applied with pressure and connected to obtain the cone like diaphragm 10. The sheets 11 and 12 consist of many carbon fabrics 16, which have a high longitudinal elasticity ratio and arranged neatly in one direction, and thermosetting resin materials, and they are constituted by a matrix material 17 which combines the carbon fabrics in one body.

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 of manufacturing the same.

In general, the frequency band of an electroacoustic transducer such as a speaker is determined mainly by the quality of the diaphragm. is the longitudinal elastic modulus, ρ is the density, and ■ is the moment of inertia of area), and the diaphragm material has a moderately large internal loss tan δ. In other words, the larger the specific longitudinal elastic modulus E/ρ, the higher the treble limit frequency (rh) will be.In order to expand the piston movement range, the frequency band of the speaker will be widened, and the bending resistance E-I will be larger. If the internal loss tan δ is moderately large and the internal loss tan δ is moderately large, the Q ratio of the diaphragm will be moderately reduced, making it difficult for split resonance to occur and flattening the characteristics (no coloration in the reproduced sound). I can do it. In addition, especially when designing acoustic diaphragms, it is necessary to reproduce transient waveforms containing high frequency components (most musical sounds correspond to this), so the characteristics of the wide knee 1 band are required. For reasons like this, material selection is a major issue, but recently, materials with a higher specific longitudinal elastic modulus E/
A diaphragm made of aluminum having ρ has been put into practical use.

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 that 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. It has excellent features in that it is easy to manufacture and inexpensive, but conventionally it has the following characteristics:
As shown in (b), one flat sheet 1 is formed by arranging reinforcing fibers with a high longitudinal modulus in the direction of arrow A, and the fiber direction is orthogonal to the bottom circumference of the dome. Since the dome-shaped diaphragm 2 is cut along with the expanded view 1 of the dome-shaped diaphragm and the cut parts are joined using a matrix material that binds these fibers to form the dome-shaped diaphragm 2, the degree of bonding of the joint 3 is weak. However, they had the disadvantage of being easy to separate during high-output vibrations and lacking in durability and reliability.

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

Therefore, the first object of the present invention is to laminate a plurality of composite sheets each made of reinforcing fibers having a high modulus of elasticity and a matrix material that binds these fibers.
The sheets of each layer are composed of a plurality of divided sheet pieces, and are laminated in a positional relationship rotated by a predetermined angle with the sheets of adjacent other layers, and the joint of each sheet piece is connected to the sheet of the other layer adjacent to the sheet of the other layer. An object of the present invention is to provide a diaphragm which is made to overlap with a diaphragm.

A second object of the present invention is to form a prepreg by arranging reinforcing fibers having a high modulus of longitudinal elasticity along the same direction and bonding these fibers with a matrix material, and to form a prepreg having substantially the same shape. - 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 not integrally bonded by heat-pressing with a force of q.

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, FIG. 3 is a sectional view taken along the line ■--■ in FIG. 2, and FIG. FIG. 2 is an enlarged cross-sectional view taken along line IV and unfolded to the original flat state. In these figures, a cone-shaped diaphragm 10 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 portion 13 is integrally formed at the open end on the base side. A bobbin (not shown) around which a voice coil is wound is connected and fixed to this neck portion 13,
is configured to do so.

Each composite material sheet) 11.12 is composed of, for example, six sheet pieces 11A to 11F and 12A to 12F, each of which is divided approximately equally in the circumferential direction. Therefore, each of the sheet pieces 11A to 11F and 12A to 12F has a substantially trapezoidal shape in a developed view of the composite material sheet 11.12, and the side lines of adjacent sheet pieces are joined to each other. In this case, the inner composite phase sheet 11 and the outer composite phase sheet 11
By stacking the material sheets 12 while rotating approximately 300 times, the joints 14 and 14 of the inner sheet pieces 11A to 11F are formed.
... is located at the center of the outer sheet pieces 12A to 12F. Therefore, the outer sheet pieces 12A to 12F
t of the inner sheet pieces 11A to 11F.
l is centered.

In this state, all the sheet pieces 11A to 1
The cone-shaped diaphragm 10 is obtained by heating and pressurizing 1F and 12A to 12F (described later) to combine them into a single piece, and as a result, the joint portions 14 of the inner sheet pieces 11A to 11F... is reinforced by the outer sheet pieces 12A to 12F, and similarly the joint 15 of the outer sheet pieces 12A to 12F
1 is reinforced by inner sheet pieces 11A to 11F.

As shown in FIG. 4, the composite material sheet 11.12 includes 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, Each of the carbon fibers 16 is made of a thermosetting resin material such as a phenol resin or an unsaturated polyester resin, and a matrix material 17 that integrally binds the carbon fibers 16. When manufacturing the cone-shaped diaphragm 10, as shown in FIG. Carbon fiber 16 sheet (prepreg>
20 is cut into a plurality of trapezoidal prepreg pieces 21&~21n having the same shape by cutting the diaphragm 20 so that the radial direction of the diaphragm itself and the direction of the fibers are in the same direction in accordance with the developed view of the predetermined cone-shaped diaphragm 10. get. These cut prepreg pieces 21&~21t are pasted on the circumferential surface of the truncated conical part 22A of the male mold 22 as shown in FIG. 6, which is formed in accordance with the shape of the diaphragm 10 to be formed. . In this case, after molding the prepreg pieces 21&~21t, the composite sheet 11 described above is
．． 12'&, therefore, the truncated conical part 22A
The first layer prepreg pieces 21a-2 pasted on the surface of
Second-layer prepreg pieces 21g to 21t are pasted on the surface of 1f with a circumferential shift of approximately 30 degrees. Next, the female mold 23 is superimposed on the male mold 22, and 150
Pressure mold while heating at a temperature of about 100°C. By this heating and pressurization, the matrix material of each prepreg piece 21a to 21t is thermally hardened to bond the fibers together, and at the same time, all the prepreg pieces 21a to 21t are integrally bonded.

After thermosetting the matrix material, the molded product is taken out from between the two molds 22 and 23, and the outermost cone edge 24 is cut to a predetermined outer diameter, as shown in FIG. 13 is cut to a predetermined length to form a cone-shaped diaphragm 10 with a laminated structure made of a composite material of reinforcing fibers of carbon fibers 16 in which fibers are arranged in the radial direction and a matrix material of epoxy resin. .

Although the above description has been made regarding the case where the 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 is. Of course. That is, FIG. 8(a) is a plan view when this invention is applied to the dome-shaped diaphragm 30, and FIG.
It is a sectional view taken along the line -■. 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. Constituent outer sheet pieces 31A to 31F and inner sheet piece 3
2A to 32F are arranged circumferentially 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 do not overlap with the joints of the inner sheet pieces. They are laminated and molded in a state where they are rotated approximately 30 degrees.

Further, in the above embodiment, two composite material sheets 11.degree. 12 are stacked, but the present invention is not limited to this, 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. be.

As described above, the diaphragm in the electroacoustic transducer according to the present invention and the method for manufacturing the same include a plurality of composite phase sheets formed by combining a plurality of sheet pieces each having a shape in which the diaphragm is divided around its central axis. When forming a diaphragm by laminating and integrally bonding the sheets, 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. The strength of the joint is high, and even under high-output vibrations, this joint will separate;
1:1 - Improves durability and reliability without bulging.

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. Has a large E/ρ and moderate internal loss,
In addition to having good vibration characteristics, it is also easy to manufacture and inexpensive, and has very large effects.

[Brief explanation of drawings]

FIGS. 1(a) and 1(b) are a perspective view and a developed view of a dome-shaped diaphragm made of a conventional composite material, and FIG. 2 shows an embodiment in which the present invention is applied to a cone-shaped diaphragm. 3 is a sectional view taken along the line ■-■ in FIG. 2, FIG. 4 is an enlarged sectional view taken along line Iv'-IV in FIG. A cross-sectional view of a main part of a sheet in which fibers are arranged in one direction, FIG. 6 is a diagram for explaining the forming of a diaphragm, FIG. 7 is a diagram for explaining cutting the end of a molded product, and FIG. 8 is a diagram for explaining the forming of a diaphragm. (a). (b) is a plan view and a sectional view taken along the line ■--■ showing an embodiment in which the present invention is applied to a dome-shaped diaphragm.
1゛□. 10.30...diaphragm, 11,12,31.32.
... Composite sheet, 11A to 11F, 12A to 12F
. 31A to 31F, 32A to 32F...Sheet piece, 14°15...Joint part, 16...Carbon fiber, 17...Matrix material, 20'...Sheet (prepreg) , 21a to 21/, ... prepreg piece, 22, ... male mold, 23 ... female mold,
A...Fiber direction. Patent applicant Nippon Musical Instruments Co., Ltd. Agent Masaki Yama (and 1 other person) Figure 1 (b) Figure 2 Figure 3 Figure 4 1'11 Figure 5 Figure 6 Figure 2A

Claims (3)

[Claims] (1) A diaphragm formed by laminating and integrally bonding multiple composite sheets made of reinforcing fibers with a high modulus of longitudinal elasticity, a matrix material that binds these fibers, and K. Each composite sheet is composed of a plurality of sheet pieces that are divided around the center axis of the diaphragm, adjacent sheets are joined to each other, and rotated at a predetermined angle with other adjacent composite sheets. 1. A diaphragm for an electroacoustic transducer, characterized in that the bonded portions of each of the sheet pieces are overlapped with the adjacent sheet pieces of another composite material sheet by being stacked in a positional relationship. (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. Prepreg pieces that are adjacent to each other in the left and right direction are brought close to each other or in contact with each other, and adjacent prepreg pieces in the thickness direction are stacked so as to partially overlap with each other to form a plurality of layers. By heating and pressurizing and curing the layer, adjacent prepreg pieces of each layer were bonded to each other, and at the same time, adjacent prepreg pieces in the thickness direction were polymerized with each other to bond all the prepreg pieces together. A method for manufacturing a diaphragm in an electroacoustic transducer, characterized in that: