JPS62193398A - Diaphragm for speaker - Google Patents

Abstract

PURPOSE:To prevent the occurrence of asymmetric split vibration and the lowering of sound pressure level in a high-pitched sound by arranging carbon fiber to the rear surface of a diaphragm, thereby making the orientation of the fiber the same in any direction to the center of the diaphragm. CONSTITUTION:A diaphragm 1 formed to conical shape has carbon fiber 2 of nearly the same length with the thickness of the diaphragm 1 nearly vertically to the surface of the diaphragm 1, and the surface of unidirectional carbon fiber prepreg, and the diameter of the fiber is several - ten-Odd microns and made to prepreg by immersing the carbon fiber bundles of PAN group or petroleum pitch group in the thermosetting resin of B-stage, for instance, unsaturated polyester resin, epoxy resin etc. As the carbon fiber is arranged nearly at right angles to the face of the cone, it is symmetric in any direction at the angle of 360 degrees to the center of the diaphragm 1. Accordingly, directional difference in strength and elastic modulus does not occur.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention involves inserting a voice coil into a magnetic gap, driving a signal current through the voice coil, and transmitting its vibrations to generate sound waves. This invention relates to a diaphragm for speakers that emit air into the air.

[Conventional technology]

Conventionally, this type of speaker diaphragm has been required to have physical characteristics such as being lightweight, having a large Young's modulus, and having a moderately large internal loss.

Paper, metal, etc. can be cited as materials that meet these requirements, but since these materials have drawbacks when used alone, they cannot be used in mixtures with other materials or as composites. many.

For example, for diaphragms whose main material is paper, glass fibers and collagen are mixed into the pulp to improve the heat resistance and moisture resistance, or carbon fiber is mixed to improve Young's modulus and heat resistance. etc.

Furthermore, speaker diaphragms using fiber-reinforced composite materials in which resin is reinforced with woven fabrics such as glass fibers, Kevlar fibers (aromatic polyamide fibers), and carbon fibers have also been developed.

[Problem that the invention seeks to solve]

However, speaker diaphragms containing these fabrics are symmetrical about the center in the warp direction, weft direction, and directions in between, but in other directions. It is asymmetrical.

Therefore, tensile strength, bending strength, and other strengths differ not only in asymmetrical directions but also in symmetrical directions, and the modulus of elasticity required for the diaphragm also differs greatly depending on the direction.

In order to improve this, two layers have been laminated with their weaving directions shifted, or three layers have been laminated with their weaving directions shifted by 60 degrees to reduce the difference in strength and elastic modulus depending on the direction.

In this way, even if multiple layers are laminated together, it is impossible for the directionality to be aligned 360 degrees with respect to the center axis of the diaphragm and for there to be no difference in strength or elastic modulus. This results in disadvantages of increased weight and cost.

[Purpose of the invention]

The present invention is intended to eliminate the above-mentioned drawbacks due to the direction of the fibers in speaker diaphragms using conventional fibers. It is an object of the present invention to provide a diaphragm for a speaker that can be symmetrical in a direction of 360 degrees with respect to an axis, eliminates differences in strength and modulus of elasticity depending on the direction, and has excellent acoustic characteristics.

[Summary of the invention]

In order to achieve the above-mentioned object, the present invention provides a sheet of unidirectional prepreg in which carbon fibers are arranged in a sheet shape in one direction and impregnated with a B-stage thermosetting resin, in a direction perpendicular to the fiber direction. The gist is a diaphragm that is rolled up into a cylindrical shape, sliced in a direction perpendicular to the central axis of the cylindrical shape, and then molded into a diaphragm shape.

[Embodiments of the invention]

FIG. 1 shows a diaphragm for a cone-shaped speaker according to the present invention.

It is shown in FIG. 2 and will be explained.

This cone-shaped diaphragm 1 has carbon fibers 2 of approximately the same length as the thickness of the diaphragm 1 arranged approximately perpendicularly on the surface of the diaphragm 10, and a skin material 3 covering the surface thereof. It is.

This carbon fiber 2 is formed from a unidirectional carbon fiber Bripreg, the fiber diameter of which is several to ten-odd microns, and a PAN-based or petroleum pitch-based carbon fiber bundle is bonded to a B-stage thermosetting resin. For example, it is made into a prepreg by impregnating it with unsaturated polyester resin or epoxy resin.

The skin material 3 may be a metal such as aluminum, titanium, beryllium, etc. molded in advance into the shape of a diaphragm, a polymer film such as polyamide, polyimide, polyester, etc., a diaphragm made of paper, carbon cloth, It is made of fiber-reinforced plastic such as Kevlar cloth.

In this cone-shaped diaphragm 1, the carbon fibers 2 are arranged in a direction substantially perpendicular to the cone surface. Therefore, there is no difference in strength or elastic modulus depending on the direction.

Next, the manufacturing method of this cone-shaped diaphragm 1 will be explained in FIGS. 3 to 6.
The diagram will be explained.

In FIG. 3, 2A is a unidirectional prepreg sheet of the carbon fibers described above.

As shown in the figure, the sheet 2A is wrapped around the core rod 4 to a required outer diameter so that the fiber direction is parallel to the axial direction of the core rod 4, that is, perpendicular to the winding direction. Wrap it in multiple layers until it becomes smooth.

Thus, the core rod 4 is extracted from the cylindrically wound sheath 1-2A, and this is sliced perpendicularly to the axis into the required thickness for the diaphragm 1 to obtain the diaphragm material 5 shown in FIG. shall be.

This diaphragm material 5 is placed on top and bottom of the skin material 3 as shown in
are stacked and inserted between the molds 7, and pressed and molded with the molds 7 as shown in FIG.

At this time, hot plates 8 are attached to the top and bottom of the mold 7 to heat the mold 7, thereby heating the skin material 3 and the diaphragm 5 during press molding.

If the skin material 3 is made of metal such as aluminum, titanium, beryllium, etc., or paper, etc., it is molded into the shape of a diaphragm in advance.
It must be made into a paper and inserted between the molds 7 together with the diaphragm material 5.

In this way, the cone-shaped diaphragm 1 shown in FIGS. 1 and 2 is manufactured.

Next, another embodiment of the present invention will be described with reference to FIG.

In this embodiment, C) 2A in FIG. 3 of the previous embodiment is used.
In the process of rolling, another material 9 is rolled between the sheets 2A, and this is sliced.

As the material 9, foamed plastic is used when the purpose is to reduce weight, paper, cloth, etc. are used when the purpose is to increase the loss, and beryllium is used when the purpose is to increase the rigidity. Highly rigid metals such as metals such as titanium, silicon carbide, and poron are used.

The embodiment shown in FIG. 8 is an embodiment for a dome-shaped diaphragm 10.

In this case, in the process shown in FIG. 3, the core ring 4 is not used and other materials 9 are wound as needed.
By slicing this, the center hole of the diaphragm material 5 shown in FIG. 4 is eliminated, and this is press-molded to form a dome-shaped diaphragm.

〔Effect of the invention〕

As described above, in the present invention, the carbon fibers are arranged toward the back side of the front surface of the imaging plate, so the directionality of the fibers is the same in any direction with respect to the center of the diaphragm. .

Therefore, in this diaphragm, the tensile strength and bending strength are the same in any direction from the center, and the elastic modulus is also the same.

Therefore, when the diaphragm vibrates, asymmetric divided vibrations do not occur and the sound pressure level in the high frequency range does not decrease.

In addition, since the carbon fibers are arranged perpendicular to the diaphragm surface, the diaphragm can be made thicker, and by sandwiching a low-density material between the carbon fiber layers, the weight can be reduced and the thickness can be reduced. Due to its large size, it becomes a single sliding plate with high bending rigidity.

Therefore, the above-mentioned asymmetric divided vibration is less likely to occur, and not only can distortion caused by this divided vibration be reduced, but also partial deformation of the diaphragm due to standing waves within the cabinet can be prevented.

[Brief explanation of drawings]

Fig. 1 is a sectional view of an embodiment of the present invention, Fig. 2 is an enlarged view of part A in Fig. 1, Figs. 3 to 6 show the manufacturing process, and Fig. 3 shows the winding process. 4 is an oblique view of the diaphragm material, FIGS. 5 and 6 are sectional views of the pressing process, and FIG. 7 is an enlarged view of part B in FIG. 4 showing the diaphragm material of another example. ,
FIG. 8 is a sectional view of the dome-shaped diaphragm. 1... Cone-shaped diaphragm, 2... Carbon fiber, 3...
Skin material, 4... Core ring, 5... Diaphragm fabric, 7...
・Press mold, 8... Hot plate, 9... Other materials, 10.
...Dome-shaped diaphragm. Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6

Claims (1)

[Claims] Carbon fibers are arranged in a sheet shape in one direction, and a sheet of unidirectional prepreg impregnated with a B-stage thermosetting resin is rolled in a direction perpendicular to the fiber direction to form a cylinder. A diaphragm for a speaker, characterized in that a thin sheet is formed by slicing carbon fibers in a direction perpendicular to its central axis to form a thin sheet in which the carbon fibers are perpendicular to the slice plane, and this is molded into a diaphragm shape.