JPS625519B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an acoustic diaphragm made of a core material and a skin material, and a method for manufacturing the same.

This type of diaphragm is made by forming a core material 1 into a honeycomb structure as shown in FIG. 1, and pasting skin materials 2 on both sides of the core material 1 to form a planar shape as shown in FIG. 2. Ru. This flat diaphragm has recently attracted attention as it is light and has relatively high strength, but it is still not strong enough, and when used in speakers, split vibration occurs and there is a limit to the sound reproduction range. .

The object of the present invention is to significantly increase the strength of the skin material of the diaphragm described above, thereby increasing the rigidity of the diaphragm itself, preventing split vibration, and significantly improving the reproduced sound range.

Embodiments of the present invention will be described below with reference to the drawings. First, the core material 1 and the skin material 2 are made of a mixture of a polymer material and graphite powder.

Polymer materials include single polyvinyl chloride, copolymers of vinyl chloride and vinyl acetate, vinylidene chloride, acrylonitrile, etc., and also thermoplastic resins such as these and polyethylene, polypropylene, and ABS resins to improve internal loss. , nitrile rubber (NR), nitrile butadiene rubber (NBR), etc., and if necessary, plasticizers and stabilizers are added to this mixture. On the other hand, the graphite powder is in the form of scales and has a particle size in the range of 0.1 to 100 μm, but generally the smaller the better, and the average particle size is preferably 5 μm or less.

In order to obtain the core material 1 and the skin material 2, the above polymer material and graphite powder are mixed at 10 to 90 wt%: 90 to 90%.
Mix in a range of 10 wt%, preferably 25 to 50 wt%: 75 to 50 wt%, add a plasticizer and stabilizer if necessary, heat knead with a mixer or kneader to obtain a kneaded material, and then mix this. is rolled over and over again by rollers to obtain a sheet material in which the graphite powder is oriented in the rolling direction.

To consider the orientation of graphite powder here, for example, polyvinyl chloride and graphite powder are kneaded at a weight ratio of 1:2, and then the graphite powder is oriented using a flat plate made by compression molding and a roller after the kneading. Comparing the Young's modulus with a flat plate made using graphite, the former flat plate has a value of approximately 3.0×10 ¹⁰ N/m ² , while the latter has a Young's modulus of approximately 7.0×10 ¹⁰ N/m ² . It can be seen that the orientation of the powder results in a significant improvement in Young's modulus.

The sheet materials obtained above are laminated in the required number so as to have a predetermined thickness, and are integrated using a hot press to form a plate material. Then, a relatively thick core material 1 and a relatively thin skin material 2 with a honeycomb structure are formed using this plate material, and the skin materials 2 are adhered to both the front and back surfaces of the core material 1 using thermoplastic resin to form a planar diaphragm. Form.

Next, the diaphragm thus completed was placed in a third
As shown in the figure, the air inside the capsule 4 sealed with the core material 1 and the skin material 2 is expanded by placing it in a high temperature bath 3 at 50°C to 150°C for about 30 minutes. A relatively thin skin material 2 containing a aged thermoplastic resin material is thermally expanded. Then, the diaphragm is taken out from the high temperature bath 3 and left in an atmosphere at room temperature, thereby cooling the entire diaphragm. As a result, the skin material 2 is cooled in an expanded state, so that a plurality of regularly arranged convex shapes 2a are formed on both sides of the diaphragm, and as a result, external pressure (sound pressure) is applied to the convex shapes 2a. The strength and rigidity will increase. Therefore, the reproduction limit frequency in the high range of the diaphragm is significantly increased.

In addition, the high temperature tank 3 is set as an oxidizing atmosphere, and the temperature is 50℃~
After heating the skin material 2 at 150°C for about 30 minutes to expand it as described above, the heating temperature is further increased to perform a surface infusibility treatment, and then the carbonization temperature is increased in a non-oxidizing atmosphere or in vacuum. When heated and fired while raising the temperature to a graphitization temperature, the diaphragm is carbonized or graphitized with convex shapes formed on the front and back surfaces. As a result, the rigidity is further improved, and the high-range reproduction limit frequency is further increased.

In the above, both the core material 1 and the skin material 2 are made of a mixed material of graphite powder and a polymer material that has been appropriately processed, but the material is not limited to this. Alternatively, a thermoplastic resin such as a thermoplastic resin alone may be used, and the manufacturing method shown in FIG. 3 is not limited to the method shown in FIG.
It may be attached to the core material 1 after that.

As described above, according to the present invention, a planar diaphragm with high rigidity can be obtained, thereby making it possible to improve the high-frequency reproduction limit frequency and suppressing split vibration.

[Brief explanation of the drawing]

FIG. 1 is an exploded perspective view of a flat diaphragm, FIG. 2 is a perspective view of the entire product, and FIG. 3 is an explanatory diagram of the manufacturing method. 1...Core material, 2...Skin material, 4...Capsule, 3
...High temperature bath.

Claims (1)

[Claims] 1. An acoustic vibration characterized in that a skin material is attached to both the front and back surfaces of a honeycomb core material, and a convex portion is formed in a portion of the skin material that corresponds to an internal capsule portion. Board. 2 A skin material made of a thermoplastic material or a material containing thermoplastic material is attached to both the front and back surfaces of the honeycomb core material, and then the air in the internal capsule is expanded in a high temperature atmosphere to form a plurality of convex portions on the skin material. A method for producing an acoustic diaphragm, in which an acoustic diaphragm is formed and then cooled to obtain an acoustic diaphragm having convex portions formed on both the front and back surfaces.