Damper for speaker

Abstract

A damper for a speaker includes a first fiber having a tensile strength of equal to or larger than 17 cN/dtex and a second fiber having a tensile elastic modulus of equal to or smaller than 200 cN/dtex. Thereby, necessary tensile strength and elasticity can be ensured. In addition, the ratio of the first fiber to the total amount of the first and second fibers is from 10% to 90%. If the ratio of the first fiber is smaller than 10%, the necessary tensile strength and elasticity cannot be obtained. Meanwhile, if the ratio of the first fiber becomes larger than 90%, punching property at the time of damper manufacture deteriorates. Thus, it is preferred that the first fiber is included at the above ratio.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a damper for a speaker device.

2. Description of Related Art

Conventionally, a woven fabric using a meta-type aromatic polyamide fiber thread, a thread made by mixed-spinning or twining a meta-type aromatic polyamide thread and a cotton thread, a polyester fiber thread, a thread made by mixed-spinning or twining the polyester fiber thread and the cotton thread, and the cotton thread is generally used as a fabric material of a damper supporting a vibration system of a speaker device. In addition, the fabric material including the above-mentioned fibers is normally impregnated with a thermosetting resin such as a phenol resin, and is formed by hot press into the damper.

Examples of the damper for the speaker using the above-mentioned threads are disclosed in Japanese Patent No. 3287750, Japanese Patent Publication No. 58-30796, and Japanese Patent Applications Laid-open under No. 8-149597, No. 10-322796 and No. 62-258596.

Since strength of the fabric material of the fiber used for the above-mentioned damper is low, there is a problem in a recent high-powered speaker that the damper is cut during the operation of the speaker. Therefore, it is necessary to improve elasticity and tensile strength of the damper fabric material.

For the purpose of solving such a problem, there is proposed a technique of using double fabric materials. However, there are such problems that the material cost increases, the weight of the damper increases, a follow-up ability to vibration operation becomes insensitive and the attached fabric materials peel off.

SUMMARY OF THE INVENTION

The present invention has been achieved in order to solve the above problems. It is an object of this invention to provide a damper for a speaker which has sufficient strength and which never breaks even when it is applied to a large input speaker.

According to one aspect of the present invention, there is provided a damper for a speaker including: first fiber having a tensile strength of equal to or larger than 17 cN/dtex; and second fiber having a tensile elastic modulus of equal to or smaller than 200 cN/dtex. Thereby, it becomes possible to ensure the necessary tensile strength and elasticity.

In a form of the above damper for the speaker, a ratio of the first fiber to a total amount of the first and second fibers may be from 10% to 90%. If the ratio of the first fiber is smaller than 10%, the necessary tensile strength and elasticity cannot be obtained. Meanwhile, if the ratio of the first fiber is larger than 90%, a punching property at the time of manufacturing damper deteriorates. Therefore, it is preferred that the first fiber is included in the above-mentioned ratio.

In a preferred example, the first fiber may be a para-type aromatic polyamide fiber, an aromatic polyester fiber (a high tensile strength polyarylate fiber), a polyimide fiber, a high tensile strength polyethylene fiber or a polypara phenylene benzobis imidazole fiber. Further, in another preferred example, the second fiber may be a meta-type aromatic polyamide fiber, a polyester fiber, an acrylic fiber, a polyhenylenesulfide fiber, a polyamide fiber or a cotton fiber.

The nature, utility, and further features of this invention will be more clearly apparent from the following detailed description with respect to preferred embodiment of the invention when read in conjunction with the accompanying drawings briefly described below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a plan view of a damper according to an embodiment of the present invention;

FIGS. 2A and 2B show partly-enlarged views of the damper according to the embodiment of the present invention;

FIG. 3 schematically shows a manufacturing process of the damper according to the embodiment;

FIGS. 4A and 4B show a result of a tensile strength test; and

FIG. 5 shows results of tensile strength tests of various kinds of mixed-woven fabrics.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The preferred embodiments of the present invention will now be described below with reference to the attached drawings.

[Structure of Damper]

FIG. 1 shows a plan view of the damper according to the present invention. In a speaker device, a damper 10 is fixed to a voice coil bobbin which vibrates in accordance with an input signal and a frame of the speaker device body, thereby to elastically support the voice coil bobbin. Specifically, an inner peripheral edge 10a is fixed to the voice coil bobbin, and an outer peripheral edge 10b is fixed to the frame of the speaker device body. In addition, in the damper 10, plural concentric corrugations 10d are formed from the inner peripheral edge to the outer peripheral edge. The damper 10 of the present invention is applicable to various kinds of speaker devices, irrespective of structures and driving systems.

FIGS. 2A and 2B show partly-enlarged views of the damper according to an embodiment of the present invention. FIG. 2A is the partly-enlarged view of the damper 10 according to a first embodiment, which enlarges an area 20 shown in FIG. 1. As shown in FIG. 2A, the damper 10 is made of a fabric material in which a fiber having tensile strength of equal to or larger than 17 cN/dtex and a fiber having a tensile elastic modulus of equal to or smaller than 200 cN/dtex are used together at the same time. Hereinafter, the two fibers are referred to as “first fiber” and “second fiber”, respectively.

“Tensile strength” is a value obtained by dividing a maximum load (FB), applied until breaking of a material at the time of applying a tensile load to the material, by an original cross-sectional area (A) of the material, and it can be expressed by an equation as follows.
Tensile strength TB=FB/A [MPa]
Therefore, as the tensile strength becomes larger, the material hardly tears, which means that mechanical strength to the tensile load is high. In addition, “tensile elastic modulus” is a ratio of a tensile stress within a tensile proportion limit and distortion caused, at the time of applying the tensile load to an object.

The examples of the first fiber having the tensile strength of equal to or larger than 17 dN/dtex are the high tensile strength fabrics, such as the para-type aromatic polyamide fiber, the aromatic polyester fiber (high tensile strength polyarylate fiber), the polyimide fiber and a ultrahigh molecular weight polyethylene fabric.

In addition, the examples of the second fiber having the tensile elastic modulus of equal to or smaller than 200 cN/dtex are the meta-type aromatic polyamide fiber, the polyester fiber, the acrylic fiber, the polyphenylenesulfide fiber and a polyethylene naphthalate fiber.

In the first embodiment shown in FIG. 2A, each of a first fiber 31 and a second fiber 32 is alternately arranged to form the damper 10. Meanwhile, in the second embodiment shown in FIG. 2B, the first fiber 31 and the second fiber 32 are used in a ratio of 1:5 to form the damper 10. In this manner, the ratio of using the first fiber and the second fiber is not limited to 1:1, and the different ratio of using them may be used.

However, as for the ratio of the first fiber and the second fiber, the ratio of the first fiber to the whole damper has to be within 10% to 90%. This is because, if the first fiber is smaller than 10% of the whole damper, the elasticity and the tensile strength as the damper fabric material are undesirably insufficient, similarly to the case that only the second fiber is used (i.e., the ratio of the first fiber is 0%). Meanwhile, if the ratio of the first fiber is larger than 90% of the whole damper, the punching property for punching the damper 10 from the fabric material into an annular shape shown in FIG. 1 at the time of the manufacturing damper is decreased, and an efficiency of operation is undesirably lowered.

A thread forming the first and second fibers is not limited to a spun yarn, and a long fiber, a short fiber, a mixed fiber of them or a finished yarn are applicable. In addition, the thicknesses of the first fiber and the second fiber may be same or different.

Diameters (thicknesses) of the above-mentioned first and second fibers preferably range from 0.3 dtex to 10 dtex. The fibers thinner than this range are not preferable because the spinning property and handling property deteriorate. The fibers thicker than this range are not preferable because the stress at the time of curving becomes high, which problematically promotes peeling off the phenol resin.

As described above, in the present invention, the damper for the speaker is formed by using the first fiber having the tensile strength of equal to or larger than 17 cN/dtex and the second fiber having the tensile elastic modulus of equal to or smaller than 200 cN/dtex. Thereby, it becomes possible to obtain effects of improving the elasticity, the tensile strength, durability of the speaker and punching property of the damper.

FIG. 3 schematically shows a manufacturing process of the damper. First, a whole cloth of the fabric material made of the above-mentioned first and second fibers is impregnated with the phenol resin. The whole cloth of the fabric material impregnated with the phenol resin is dried with hot air, and the corrugations 10d shown in FIG. 1 are formed thereto in a hot press process. Then, in a die cutting process, the fabric material is punched into the annular shape as shown in FIG. 1. In this way, the damper 10 is manufactured.

EXPERIMENTAL EXAMPLE

Next, the description will be given of confirmatory experimental examples of the above-mentioned respective effects by the damper of the present invention. In experiments below, a fabric material of threads of yarn count 10 is used, and the number of woven warp and weft threads in the fabric material is 25/inch. In addition, as the first fiber having the tensile strength of equal to or larger than 17 cN/dtex, a para-type aromatic polyamide fiber “TECHNORA” (Registered Trademark) produced by TEIJIN TECHNO PRODUCTS LIMITED is used. As the second fiber having the tensile elastic modulus of equal to or smaller than 200 cN/dtex, “CONEX” (Registered Trademark) produced by the same company is used. As shown in FIG. 2A, each of the first and second fibers is alternately woven to form the fabric material of the damper.

(Experiment of Elasticity)

The damper fabric material is cut into a width of 20 mm, and a 400 g weight is attached thereto. Then, an experiment of curving the material at the rate of 36 times per minute in a to-and-fro of 180° (90° on one side) is executed. In this experiment, a number of times at which the damper fabric material is torn is measured (1 to-and-fro is counted 1 time). The damper fabric material made of only the second fiber tore at the curving number of 15000 to 20000 times. Meanwhile, as for the fabric material according to the above-mentioned embodiment, made of the first and second fibers, the second fiber was cut at the curving number of 50000 times, but the first fiber was not cut at the curving number of 100000 times. Therefore, the fabric material itself did not tear. As a result, it is confirmed that the elasticity of the damper fabric material of the present invention using the first and second fibers is improved.

(Experiment of Tensile Strength)

The tensile strength of the damper fabric material cut into a width of 25 mm is measured. FIG. 4A shows a measured result thereof. The fabric material using only the second fiber tore at about 650 N. Meanwhile, the fabric material according to the above embodiment, using the first and second fibers, tore at about 1250 N. As a result, it is confirmed that the tensile strength of the damper fabric material of the present invention using the first and second fibers is improved to be approximately double.

In the case of the fabric material using only the first fiber, the impregnating property of the phenol resin to the fabric material is low. Thus, when the stress is set to about 800 N at the time of the tensile experiment, the weft (cross threads) of the fabric material held by a tensile testing machine slid and fell out. FIG. 4B shows this state. When the broken line area 40 is held by a holding tool of the tensile testing machine and the stress is applied thereto, the warp remain without being cut, but the weft slid and shifted. Thereby, it is found out that strength in practical use of the damper fabric material using the first and second fibers according to the embodiment of the present invention is higher.

(Durability Test)

For the speaker device including the damper fabric material made of only the second fiber and the speaker device including the damper made of the first and second fibers according to the embodiment of the present invention, the continuous-time operation with 800 W input is executed. The damper made of only the second fiber is cut within the continuous-time operation of 72 hours. Meanwhile, the damper made of the first and second fibers according to the embodiment is not cut within the continuous-time operation of 72 hours. As a result, it is confirmed that the durability of the speaker device using the damper fabric material of the present invention is improved.

(Damper Punching Test)

In the die-cutting process of the damper shown in FIG. 3, the damper fabric material using only the second fiber cannot be die-cut (cut with a die). On the other hand, the damper fabric material using the first and second fibers according to the embodiment can be die-cut without any trouble.

After the forming process by the hot press, the die-cut process for punching the fabric material into the damper shape can be easily executed for the second fiber having the tensile elastic modulus of equal to or smaller than 200 cN/dtex. Meanwhile, even though the punching is executed for the first fiber having the tensile strength of equal to or larger than 17 cN/dtex similarly to the second fiber, the first fiber cannot be often cut due to the high tensile strength, and the productivity lowers. It is confirmed that since the damper fabric material according to the embodiment of the present invention includes the second fiber having the tensile elastic modulus of equal to or smaller than 200 cN/dtex, the punching is easier and the productivity is higher compared with the damper fabric material using only the first fiber.

In the above embodiment, as the first fiber and the second fiber, TECHNORA and CONEX are used for the experiment, respectively. However, even if each of the first and second fibers using other threads of yarn count 10 is alternately woven such that the number of woven warp and weft threads is 25/inch, thereby to manufacture the damper, it is possible to obtain the damper with the high tensile strength, durability and productivity. FIG. 5 shows tensile strength measuring data by each combination. In the punching test shown in FIG. 5, it is examined whether or not the fabric material impregnated with the phenol resin and then formed by the hot-press can be cut into the damper by the punching in the damper manufacturing line. As for an item “punching property” shown in FIG. 5, “◯” shows that the punching is sufficiently possible, and “X” shows that the punching is impossible.

In FIG. 5, used “TECHNORA” produced by TEIJIN TECHNO PRODUCTS LIMITED is used as the para-type aromatic aramid fiber, “VECTRAN” produced by KURARAY CO., LTD. is used as the aromatic polyester fiber, “DYNEEMA” produced by TOYOBO.CO., LTD. is used as a high tensile strength polyethylene fiber, “P84” produced by TOYOBO.CO., LTD. is used as a polyimide fiber, “ZYLON” produced by TOYOBO.CO., LTD. is used as a polyphenylene benzobis oxazole fiber (PBO fiber), “CONEX” produced by TEIJIN TECHNO PRODUCTS LIMITED is used as the meta-type aromatic polyamide fiber, “TETORON” produced by TEIJIN TECHNO PRODUCTS LIMITED is used as a polyester fiber, “VONNEL” produced by MITSUBISHI RAYON CO., LTD. is used as the acrylic fiber, “TORCON” produced by TORAY INDUSTRIES, INC. is used as the polyphenylenesulfide fiber, and “TORAY NYLON” produced by TORAY INDUSTRIES, INC. is used as the polyamide fiber.

The invention may be embodied on other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description and all changes which come within the meaning an range of equivalency of the claims are therefore intended to embraced therein.

The entire disclosure of Japanese Patent Application No. 2004-314167 filed on Oct. 28, 2004 including the specification, claims, drawings and summary is incorporated herein by reference in its entirety.

Claims

1. A damper for a speaker comprising:

first fiber having a tensile strength of equal to or larger than 17 cN/dtex; and

second fiber having a tensile elastic modulus of equal to or smaller than 200 cN/dtex.

2. The damper for the speaker according to claim 1, wherein a ratio of the first fiber to a total amount of the first and second fibers is from 10% to 90%.

3. The damper for the speaker according to claim 1, wherein the first fiber is one of a para-type aromatic polyamide fiber, an aromatic polyester fiber, a polyimide fiber, a high tensile strength polyethylene fiber and a polypara phenylene benzobis imidazole fiber.

4. The damper for the speaker according to claim 1, wherein the second fiber is one of a meta-type aromatic polyamide fiber, a polyester fiber, an acrylic fiber, a polyhenylenesulfide fiber, a polyamide fiber and a cotton fiber.