JPS5825797A - Diaphragm for speaker - Google Patents

Abstract

PURPOSE:To produce a speaker of less peak and dip, by molding a low foamed polypropylene, where the concentration is within a specific range, to form a diaphragm. CONSTITUTION:The pressure of the fused liquid of a polypropylene containing a prescribed quantity of an organic foamed material such as azodicarbonamide is reduced to the air pressure to form a sheet consisting of low foamed polypropylene where the thickness is about 0.5mm. and the density is 0.85g/cc (preferably, 0.83-0.89g/cc). The Young's modulus of this sheet is about 8,900kg/cm<2>. The sheet is molded to a shape like a cone having a maximum diameter 250mm.phi by the vacuum molding method to obtain a diaphragm for dynamic speaker. Thus, a speaker which has a flat characteristic of less peak and dip and is superior in durability is produced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a diaphragm for a speaker, and particularly to a diaphragm for a speaker formed by molding low-foam polypropylene.

-a) The characteristics of the diaphragm used in high-fidelity speakers include relatively high elasticity, appropriate internal loss, and light weight. From the viewpoint of practical use and production process, it is required that the material be highly moisture resistant and processable.

However, since paper material has appropriate internal loss and is lightweight (average density is 0.5 g/CC), diaphragms mainly made of paper made of heat-losing pulp material have traditionally been used. is frequently used.

However, the above-mentioned paper material is subjected to a so-called beating treatment in the paper-making process, but the above-mentioned physical properties change variously depending on the processing conditions, so it is not always possible to ultimately make the acoustic characteristics as a diaphragm uniform. It's not easy,
Also, due to the nature of the material, it tends to be difficult to obtain high elasticity.
Furthermore, the processability in molding and the moisture resistance during use were not fully satisfactory. Furthermore, speakers with paper diaphragms tend to have significant peak-dip characteristics in their frequency characteristics, so they also have another drawback in that it is difficult to obtain faithful reproduction of sound.

On the other hand, recently attempts have been made to increase the elasticity by using alloys such as beryllium, lium alloys, and titanium alloys, but originally the density of these alloys is approximately 1
Since it is several orders of magnitude larger, it is difficult to obtain a high output sound pressure level, and due to the nature of the metal, it has poor workability, making it difficult to mold it into various square shapes.

The present invention has been made to eliminate the drawbacks of the conventional speaker diaphragms described above, and in particular aims to improve workability and moisture resistance as well as frequency characteristics as a speaker.

Embodiments of the present invention will be illustrated and described below.

One embodiment of the diaphragm of the present invention is manufactured by reducing the pressure of a polypropylene melt containing a predetermined amount of an organic foaming material such as azothicarbonamide to atmospheric pressure, and has a thickness of approximately Q, 5 mm. , the maximum diameter is 2 by the sea-forming method of low foam polypropylene with a density of 0.85g/CC.
It was processed into a cone shape with a diameter of 50 mm, and a dynamic speaker was manufactured using this. On the other hand, we manufactured a dynamic speaker with the same structure as above using a cone made of paper material with the same shape and dimensions.

FIG. 1 shows the frequency characteristics of both speakers.

In the figure, curve A is the frequency characteristic of the speaker according to the present invention, and curve 8 is the frequency characteristic of the speaker made of paper cone. As shown in the figure, the A curve has a peak.

There are no dips, and therefore a more faithful reproduction sound is obtained.

In addition, as a result of conducting similar experiments for density in the range of 0.83 to 0.89 g/cc and Young's modulus in the range of 8,600 to 9,120 kg/cm2, the low foaming according to the present invention was found compared to a speaker using a paper cone diaphragm. It was experimentally confirmed that speakers using polypropylene diaphragms have flatter frequency characteristics.

Furthermore, since low-foam polypropylene can be vacuum formed, production efficiency can be dramatically improved compared to conventional paper cones. Furthermore, since the diaphragm has excellent environmental characteristics such as moisture resistance and weather resistance, it is possible to manufacture a speaker with a long durability by using the diaphragm of the present invention.

Furthermore, the sound quality of a speaker using the diaphragm of the present invention is rich in force, softness, brightness, and delicacy, and a well-balanced sound quality can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a drawing comparing the frequency characteristics of a speaker using the diaphragm of the present invention and a conventional speaker using a paper cone diaphragm. Patent applicant: Tonegen Co., Ltd. Patent attorney Koji Onishi

Claims (1)

[Claims] A speaker diaphragm characterized by being molded from low-foam polypropylene having a density of 0.83 to 0.89 g/CC.