JPH07101955B2 - Vibration plate for electro-acoustic transducer - Google Patents

Description

TECHNICAL FIELD The present invention relates to a diaphragm for an electroacoustic transducer.

BACKGROUND ART Conventionally, a dynamic speaker has been known as an electroacoustic transducer. As a diaphragm for an electroacoustic transducer of such a speaker, a cone-shaped, flat-plate-shaped diaphragm, a dome-shaped center cap, or the like is known.

The following conditions are generally required for the diaphragm for an electroacoustic transducer.

Low mass or low density.

Have a large Young's modulus.

There is a moderate internal loss.

The condition of is to increase the efficiency and improve the transient characteristic, and the condition of is to widen the reproduction band of the frequency, improve the transient characteristic, and extend the treble range. This is to suppress vibration, reduce the peak dip of high-frequency resonance, and flatten the sound pressure frequency characteristic.

In order to satisfy the above conditions, paper mainly composed of wood pulp has been conventionally used. However, the paper has a specific elastic modulus (E /
Since ρ …… E: Young's modulus, ρ: density) are not so large, there is a drawback that the reproduction frequency sound pressure level is low. In addition, paper is easily affected by humidity and its physical properties become unstable.

In recent years, metal diaphragms such as titanium and beryllium and plastic diaphragms such as polypropylene have been used. However, although the metal diaphragm has rigidity, it has a drawback that it has a large density and a large weight and further has a small internal loss. Further, a diaphragm made of polypropylene or the like has a low density but also a low rigidity, and as a result, the thickness and weight must be increased before use. In addition, there is a drawback that the heat resistance is poor.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a diaphragm for an electroacoustic transducer which compensates for the above-mentioned drawbacks and is excellent not only in improving sound pressure frequency characteristics but also in heat resistance, humidity resistance, dimensional stability and the like. is there.

The electroacoustic transducer diaphragm of the present invention is represented by the following formulas I and II.

The repeating unit of formula I is II
The main structural member is a fiber made of wholly aromatic polyester, which is a large amount component larger than the repeating unit of the formula.

Structure of the Invention The wholly aromatic polyester fiber used in the present invention is obtained by melt spinning a polyester comprising a combination of two or more kinds of repeating units represented by the following formulas I to VIII.

These wholly aromatic polyesters are designated as I-
This is because it is a polyester composed of a combination of repeating units of the formula VIII. The most typical wholly aromatic polyester is a combination of repeating units of formulas I and II, in which the repeating unit of formula I is used as the major component and the repeating unit of formula II as the minor component. Is desirable from the standpoint of the rigidity of polyester and also from the viewpoint of thermal characteristics. Also, I
And polyesters obtained by appropriately copolymerizing other single or plural units as a minor component as long as the main component is a repeating repeating unit consisting of the combination of the formula II.

In short, the wholly aromatic polyester fiber used in the present invention has a yarn strength and Young's modulus of about 20 g / d or more,
About 600 g / d or more is required as a yarn for a woven fabric which uses this fiber as a base fabric of a main structural member of a diaphragm for an electroacoustic transducer. It is well known that the larger the Young's modulus is, the more preferable it is for a diaphragm for an electroacoustic transducer. Therefore, from the combination of the repeating units of the formulas I and II, other formulas such as formula III or repeating units can be used. Furthermore, it is better to copolymerize the Young's modulus to 800 to 900 g / d. And the specific gravity of wholly aromatic polyester fiber comprising a combination of repeating units of formulas I and II is about 1.4.
Thus, it has the advantages that it is less hygroscopic than conventional publicly known polyparaphenylene terephthalamide fibers (Kevlar, a registered trademark of DuPont) and that there is little deterioration in performance under repeated dry and wet conditions. This point corresponds well to the actual use conditions of the diaphragm for an electroacoustic transducer, and can be said to be a desirable characteristic of the base cloth.

Examples of the present invention, using such a woven fabric of wholly aromatic polyester fiber as a base fabric for a diaphragm, a conventionally known thermosetting resin, for example, an epoxy resin or a phenol resin or a thermoplastic resin, for example, polypropylene, nylon, It is provided as a vibration plate by being fixed and molded with a polyarylate resin into a predetermined shape. A conventionally known method can be used as it is as a fixing molding method for forming a vibration plate shape. And as the woven fabric of the base fabric, it is desirable that all the aromatic polyester fibers are all warp yarns and weft yarns, but about 10 to 20% of the warp yarns and / or weft yarns are replaced with other fibers, for example, carbon fibers or Kevlar. It may be a woven cloth. When a plurality of woven fabrics are laminated to form a base fabric, the main woven fabric may be made of wholly aromatic polyester fiber, and a woven fabric made of other fibers may be used in a supplementary amount.

Examples Hereinafter, the present invention will be described based on Examples.

(1) Example 1 A wholly aromatic polyester fiber consisting of the repeating unit I: II = 3: 1 of the above formula (yarn physical properties: 1000d / 200f, specific gravity 1.44, strength 25g
/ d, Young's modulus 610 g / d) yarn 1000d / 200f was used as warp yarn and weft yarn, 20 yarns per inch were struck, and plain weave fabric was used as the base fabric. The fabric weight is
It was 170 g / m ² and the thickness was 0.15 mm. Using this base cloth, a polyethylene cone derivative (epoxy resin) was used as an adhesive resin for fixing and molding to prepare a speaker cone having a diameter of 16 cm. That is, the base cloth is impregnated into a methyl ethyl ketone-dispersed resin liquid of a polyglycidyl ether resin using non-absorption maleic acid as a curing agent, and then 100
The resin was B-staged by drying in hot air at ℃ for 10 minutes. Then, in a mold of a specified shape, mold this product at the molding temperature.
Press molding was performed at 210 ° C. and a pressure of 4.0 kg / cm ² for 2 minutes. Thus, a fully cured speaker cone having a diameter of 16 cm was obtained.

A partially enlarged cross section of the obtained speaker cone 3 is shown in FIG. The speaker cone comprises a base fabric 2 of wholly aromatic polyester fibers fixed in a solidified epoxy resin 1. A center cap was also formed similarly to the speaker cone 3.

(2) Example 2 As Example 2, using the wholly aromatic polyester fiber in Example 1, the yarn was changed from 1000d / 200f to 1500d / 300f, and a woven fabric having a number of threads of 13/13 / inch was used. In the same manner, a speaker cone with a diameter of 16 cm was created. The conditions of the B stage and the press molding conditions are the same as in Example 1.

(3) Example 3 As Example 3, as in Example 1, the yarn 1000 d /
A 12 cm speaker cone was created using 200f. In this case, the pressing pressure is 6.5 kg / cm ² .

(4) Control Example As a symmetric example 1, wood pulp mainly produced by papermaking (NBKP 20 ° S
R) speaker cone was created. As Symmetry Example 2, a speaker cone made of polypropylene resin was produced by injection molding. As a control example 3, a carbon fiber material was used in Example 1
A speaker cone fixed and molded with a polyethylene oxide derivative (epoxy resin) was prepared under the same conditions as in.

Various physical properties of the speaker cones of Examples 1 to 3 are shown in Table 1 together with those values of the speaker cones of Comparative Examples 1 to 3 other than the present invention.

Generally, the physical properties required for a speaker cone are as small as possible in density, and as large in Young's modulus as possible.
It is desired that the internal loss be as large as possible and the propagation velocity be as large as possible. A speaker cone that satisfies these conditions at the same time is considered ideal.
Above all, Young's modulus and internal loss are the most important physical properties,
A speaker cone that has both of these two values as large as possible is desired.

From this point, looking at the results in Table 1, Examples 1 to 1 of the present invention
It can be said that the speaker cone of No. 3 is a speaker cone with well-balanced physical properties. The speaker cones of Examples 1 to 3 did not change or deteriorate even in the environmental tests of the following items. Therefore, there is no problem even if they are used as, for example, an automobile speaker or an underwater speaker.

Heat resistance test …… 105 ℃, 48 hours Cold resistance test …… −20 ℃, 48 hours Moisture resistance test …… 40 ℃, 95% Rh, 96 hours Water resistance test …… In 20 ℃ water, after 24 hours 80 ℃ 4 hours Light resistance test ... xenon fade meter 200 hours FIG. 2 is a cross-sectional view of a dynamic speaker manufactured by individually using a 16 cm diameter speaker cone and a center cap according to Example 1 and Comparative Example 1. The yoke 6 and the magnet 7 are adhered to the yoke plate 5,
Further, the plate 8 is attached to form a magnetic circuit. On the other hand, a voice coil 10 is wound around a voice coil bobbin 9, supported by a damper 11 and set in a magnetic circuit. The speaker cone 3 is attached to the gasket 13 and the frame 14 via the edge 12, and the central opening (neck) of the speaker cone is bonded to the voice coil bobbin and further covered with the center cap 4.

FIG. 3 is a sound pressure frequency characteristic diagram of the 16 cm diameter speaker according to the first embodiment and the first comparative example. In the figure, curve A is the reference example 1.
The sound pressure frequency characteristic of the speaker made from the paper making cone according to the above, and the curve B is the sound pressure frequency characteristic of the speaker made from the cone according to the first embodiment. It can be seen that the one according to Example 1 has a flat sound pressure frequency characteristic in the middle and high bands as compared with the one according to Comparative Example 1.

Effects of the Invention As described above, according to the present invention, since the wholly aromatic polyester fiber is the main constituent member, the Young's modulus is high, the density is low, the unit area weight is small, and an appropriate amount of internal loss is obtained. A vibrating plate for an electroacoustic transducer having the above is obtained.

[Brief description of drawings]

FIG. 1 is a partially enlarged cross-sectional view of a diaphragm for an electroacoustic transducer according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of a dynamic speaker, and FIG. 3 is a sound pressure frequency characteristic of the first embodiment and a comparative example 1. It is a figure. Explanation of symbols of main parts 1 …… Epoxy resin 2 …… Whole aromatic polyester fiber base cloth 3 …… Vibration plate

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tatsumi Kanamaru 1-1239 Umeda, Kita-ku, Osaka City, Osaka Prefecture Kuraray Co., Ltd. (72) Inventor, Kazuo Tsuchiya Shinmachi, Shinmoji, Mamurogawa-cho, Mogami-gun, Yamagata Prefecture No. 954 No. 1 in Mogami Electric Co., Ltd. (72) Inventor Susumu Shimura, Shinmachi, Mamurogawa-cho, Mogami-gun, Yamagata Shiono No. 1 No. 1 Mogami Electric Co., Ltd. (72) Masanori Takahashi Shincho, Mamurogawa-cho, Mogami-gun, Yamagata Prefecture Shiono No. 1 in 954 Mogami Denki Co., Ltd. (56) Reference JP 62-36999 (JP, A) JP 1-93999 (JP, A)

Claims (4)

[Claims] 1. A compound represented by the following formulas I and II: The repeating unit of formula I is II
A diaphragm for an electroacoustic transducer, characterized in that the main structural member is a fiber made of wholly aromatic polyester, which is a large amount component larger than the repeating unit of the formula. 2. The main structural member is made of at least one woven fabric in which fibers made of wholly aromatic polyester are used as warp yarns and weft yarns, and synthetic resin is adhered to the main structural member. The diaphragm for an electroacoustic transducer according to Item 1. 3. The diaphragm for an electroacoustic transducer according to claim 2, wherein the total resin is a thermosetting resin. 4. The diaphragm for an electroacoustic transducer according to claim 2, wherein the synthetic resin is a thermoplastic resin.