JPH04283000A - Diaphragm for speaker - Google Patents

Abstract

PURPOSE:To realize the diaphragm for speaker with excellent heat resistance, moisture-proof, weather-proof and stiffness or the like by employing polyimide fibers for high elastic fibers. CONSTITUTION:Polyimide fibers are used for high elastic fiber groups and the high elastic fiber groups are linked by a thermoplastic or thermosetting synthetic resin. The diaphragm for speaker with the constitution as above has a large stiffness and internal loss and small apparent density and obtain excellent heat resistance, moisture-proof, weather-proof and stiffness or the like. Moreover, the stiffness is considerably improved by using the high elastic fiber group as a woven cloth and the diaphragm with excellent acoustic characteristic is realized by employing a woven cloth in which the polyimide fiber bundles and carbon fiber bundles are orthogonally crossed with each other.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diaphragm for a speaker in an electroacoustic transducer using highly elastic fibers.

0002

[Prior Art] As is well known, in a speaker diaphragm, a localized part of the diaphragm, such as the center or the periphery, is driven by a voice coil and emits sound waves. Since it is not a completely rigid body, it is difficult to perform piston movement except in the extremely low frequency band, and normally it becomes a high-order split vibration mode and the frequency characteristics deteriorate, so it is necessary to expand the piston movement band to as high a frequency band as possible. In addition, in order to suppress the resulting split vibration, the material constituting the diaphragm is required to have as much rigidity as possible and a relatively high vibration energy absorption capacity.

As a speaker diaphragm that satisfies these conditions, in recent years, high modulus fibers such as glass fibers, carbon fibers, aramid fibers, etc., or mixtures of two or more types of high modulus fibers have been used as woven fabrics, non-woven fabrics, etc. These are further laminated and bonded together using a resin.

0004

[Problems to be Solved by the Invention] In such conventional speaker diaphragms, those using carbon fibers or aramid fibers are known to have high elasticity, but the diaphragms made of carbon fibers are bonded with resin. However, although the rigidity (Young's modulus E) is high, it is still not sufficient, and the internal loss (tan δ) is small, so it has the disadvantage that peaks and dips occur at specific frequencies in the frequency characteristics. Although a speaker diaphragm made of aramid fiber woven fabric has high elasticity, it has poor heat resistance, moisture resistance, and weather resistance, making it unsuitable for use in harsh environments such as outdoors or inside a vehicle.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a speaker diaphragm having excellent heat resistance, moisture resistance, weather resistance, rigidity, etc., by eliminating the drawbacks of the conventional examples.

[0006]

[Means for Solving the Problems] To achieve the above object, a speaker diaphragm according to the present invention includes a group of high elastic fibers using polyimide fibers, and a thermoplastic or It is characterized by being made of a thermosetting synthetic resin, or by making the high elastic fiber group into a woven fabric, or by making the woven fabric by making polyimide fiber bundles and carbon fiber bundles orthogonal to each other. It is characterized by being made of cloth.

The polyimide fiber used in the present invention is spun from polyimide soluble in an organic solvent.

[0008]

[Function] In a speaker diaphragm with such a configuration, polyimide fibers are used as high elastic fibers, so the rigidity (Young's modulus E) and internal loss (tan δ) are large, and the density ρ of the polyimide fibers is Since it is small and is bonded with resin, the apparent density ρ of the speaker diaphragm becomes smaller, and the value of E/ρ becomes larger.

[0009] In addition, speaker diaphragms made of woven polyimide fibers have significantly improved rigidity (Young's modulus E) due to their woven fabric structure, compared to conventional speaker diaphragms made of non-fibrous polyimide. do.

[0010] In a woven fabric made of polyimide fibers and high modulus fibers other than polyimide fibers, vibrations specific to each high modulus fiber can be suppressed.

[0011]

EXAMPLES Examples of the present invention will be described in detail. As Example 1, polyimide fiber bundles (1000 filaments) were plain woven at a fiber bundle density of 12.5 fibers/inch, and this woven fabric was molded under heat and pressure into a cone shape using polypropylene, which is a thermoplastic resin, as the binding resin. By doing so, the speaker diaphragm according to the present application can be obtained.

Next, as Example 2, a polyimide fiber bundle (
1000 filaments) and carbon fiber bundles (1000 filaments) intersect with each other at a fiber bundle density of 12.
A speaker diaphragm according to the present invention can be obtained by plain weaving at a rate of 5 strands/inch and molding this woven fabric under heat and pressure into a cone shape using polypropylene, which is a thermoplastic resin, as a binding resin.

Above, the speaker diaphragm according to the present invention has been described in detail based on examples considered to be representative. However, in embodiments of the present invention, for example, polyimide fiber woven fabric and carbon fiber woven fabric are used as fibers. By laminating them in different directions and molding them under heat and pressure into a cone shape using thermosetting resin such as epoxy resin, etc.
The structure of the above embodiment is not limited to the material or combination method of other high modulus fibers to be combined with polyimide fibers, the material of thermosetting or thermoplastic resin to combine high modulus fibers, the method of binding high modulus fibers, etc. The present invention is not limited to the above, but may be implemented with appropriate modifications as long as it has the constituent features set forth in the claims, exhibits the functions of the present invention, and has the effects described below.

[0014]

[Effect] The physical properties of the speaker diaphragm obtained in Example 1 and Example 2 and the physical properties of the speaker diaphragm obtained by molding carbon fiber under the same conditions as Example 1 as a conventional example are as follows. It is shown in Table 1.

[0015]

[Table 1] As is clear from Table 1 above, the speaker diaphragm according to the present invention has higher rigidity (Young's modulus E) than the conventional speaker diaphragm made of carbon fiber woven fabric. , density ρ
Since E/ρ is small, the value of E/ρ becomes large, which widens the piston motion band, suppresses split vibration, and provides excellent acoustic characteristics.

[0016] Polyimide also has excellent heat resistance, moisture resistance, and weather resistance, making it suitable for use in harsh environments such as outdoors and inside cars.
In particular, a speaker diaphragm base material made of polyimide fibers bonded with a thermosetting resin is suitable for use in high-temperature locations.

[0017] Woven fabrics made by combining polyimide fibers with other high modulus fibers (such as carbon fibers) and bonded with thermosetting or thermoplastic synthetic resins produce vibrations specific to each material. It has excellent acoustic properties because it cancels out each other, and by selecting high elastic fibers to be combined,
A speaker diaphragm with desired characteristics can be obtained.

Claims (3)

[Claims] 1. A diaphragm for a speaker comprising a group of high elastic fibers using polyimide fibers and a thermoplastic or thermosetting synthetic resin for bonding the group of high elastic fibers. 2. The speaker diaphragm according to claim 1, wherein the high elastic fiber group is a woven fabric. 3. The speaker diaphragm according to claim 2, wherein the woven fabric is a woven fabric made of polyimide fiber bundles and carbon fiber bundles arranged orthogonally to each other.