JP2007258864A - Speaker diaphragm and speaker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a speaker diaphragm, having superior balance between the Young's modulus and the internal loss, and to provide a speaker. <P>SOLUTION: In the speaker diaphragm, a surface material is provided to at least one side of a resin layer of a foaming structure, and the surface material contains fabric and/or nonwoven fabric. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a speaker diaphragm and a speaker. More specifically, the present invention relates to a speaker diaphragm and a speaker excellent in balance between Young's modulus and internal loss.

  In general, as a speaker diaphragm material, a paper made of short fibers such as pulp, a metal thin plate molded, a thermoplastic resin such as polypropylene injection molded, and the like have been proposed. The speaker diaphragm made of polypropylene resin has a disadvantage that it is relatively heavy.

Therefore, for the purpose of weight reduction, a speaker diaphragm formed of a polystyrene resin foam has been proposed (for example, see Patent Document 1). However, the speaker diaphragm has a problem that it does not have a high Young's modulus and an appropriate internal loss, which are characteristics required for the speaker diaphragm. Further, the speaker diaphragm has a problem of poor response because energy is not easily transmitted. Further, the speaker diaphragm has a problem that the appearance is very bad in appearance.
JP 2000-224692 A

  The present invention has been made to solve the above-described conventional problems, and a main object thereof is to provide a speaker diaphragm having an excellent balance between Young's modulus and internal loss.

  The speaker diaphragm of the present invention has a surface material on at least one side of a resin layer having a foam structure, and the surface material includes a woven fabric and / or a nonwoven fabric.

In a preferred embodiment, the density is 0.01 to 0.8 g / cm ³ .

  In preferable embodiment, the average diameter of the bubble in the foam structure of the said resin layer is 1-500 micrometers.

  In a preferred embodiment, the resin layer contains a styrene resin.

  In a preferred embodiment, the woven or non-woven fabric constituting the surface material is formed of polyethylene naphthalate fibers and / or aramid fibers.

  In a preferred embodiment, an adhesive layer is provided between the resin layer and the surface material.

  According to another aspect of the present invention, a speaker is provided. This speaker includes the above-described speaker diaphragm.

  According to the present invention, by providing the surface material, a laminated structure is formed, and a speaker diaphragm having an excellent balance between Young's modulus and internal loss can be obtained. In addition, the formation of the laminated structure improves the difficulty in transmitting the energy unique to the foam and can provide excellent response. As a result, a speaker diaphragm having an excellent S / N ratio and a wide bandwidth can be obtained. Furthermore, by forming the laminated structure, the resin diaphragm is not exposed and a speaker diaphragm excellent in design can be obtained.

The speaker diaphragm of the present invention has a surface material on at least one side of a resin layer having a foam structure, and the surface material includes a woven fabric and / or a nonwoven fabric. The density of the speaker diaphragm of the present invention is preferably 0.01 to 0.8 g / cm ³ , more preferably 0.03 to 0.5 g / cm ³ , and particularly preferably 0.05 to 0.3 g / cm ^3. It is. By having a density in such a range, a speaker diaphragm having excellent specific elasticity and excellent high-frequency elongation can be obtained.

A. Resin layer The resin layer has a foamed structure. The density of the resin layer is preferably 0.01 to 0.1 g / cm ³ .

The average diameter of the bubbles in the foam structure of the resin layer is preferably 1 to 500 μm, more preferably 20 to 500 μm, and particularly preferably 50 to 300 μm. When the average diameter of the bubbles is within such a range, a speaker diaphragm having excellent mechanical strength while being lightweight can be obtained. Furthermore, there is an effect of improving internal loss. The cell layer preferably has a cell density of 100 to 1000 / mm ² , more preferably 200 to 500 / mm ² . By having a bubble density in such a range, the balance between strength and weight reduction can be further improved.

  The thickness of the resin layer can be set to any appropriate thickness. The thickness of the resin layer is preferably 0.5 to 15 mm, more preferably 1 to 10 mm.

  Arbitrary appropriate resin is employ | adopted as resin which forms the said resin layer. The resin layer preferably contains a styrene resin. Specific examples of the styrene resin include polystyrene, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, styrene-acrylonitrile copolymer, styrene graft copolymer, and the like.

  Any appropriate method can be adopted as a method of forming the resin layer. The resin layer is formed, for example, by foaming resin particles containing at least the resin that forms the resin layer described above. Details will be described later.

B. Surface Material The speaker diaphragm of the present invention has a surface material on at least one side of the resin layer. By providing the surface material, a speaker diaphragm having an excellent balance between Young's modulus and internal loss can be obtained. Further, by providing the surface material, the difficulty in transmitting energy can be improved and the response can be excellent. As a result, a speaker diaphragm having an excellent S / N ratio and a wide bandwidth can be obtained. When the surface material is provided only on one side of the resin layer, the surface material is preferably provided on the front side (when the speaker is mounted). This is because the resin layer is not exposed and a speaker with excellent design can be obtained.

  The surface material includes any suitable woven and / or non-woven fabric. The surface material may be a single layer of woven fabric and / or nonwoven fabric, or may be a laminate of woven fabric and / or nonwoven fabric. When surface materials are provided on both sides of the resin layer, the respective surface materials may have the same configuration or different configurations.

Any appropriate structure can be adopted as the woven structure of the woven fabric. For example, plain weave, twill weave, satin weave, or a combination thereof. A plain weave is preferred. This is because the mechanical properties in the fiber axis direction of the woven fabric are excellent, so that deep drawing can be performed strongly. Therefore, it is particularly preferable for use with a large-diameter cone type diaphragm. The surface density in the case of plain weaving is appropriately selected depending on the properties of the fibers used (for example, mechanical properties, fiber diameter, fiber length) and the like, but is typically 100 to 300 g / m ² . This is because the surface density in such a range has a large effect of increasing strength and is excellent in moldability. Such areal density includes, for example, a woven density of 40 vertical / inch × 40 horizontal / inch or 17 vertical / inch × 17 horizontal / inch.

The nonwoven fabric can be formed by any appropriate method. Typical examples of the method for forming the nonwoven fabric include a wet manufacturing method using a fluid such as water, a dry manufacturing method in which short fibers are mechanically entangled randomly. A wet process is preferred. This is because the anisotropy of mechanical properties can be kept small, and a nonwoven fabric with good moldability can be obtained. The basis weight (area density) of the nonwoven fabric can vary depending on the purpose, but is typically 30 to 150 g / m ² .

  Arbitrary appropriate fiber may be employ | adopted as a fiber which forms the said woven fabric or a nonwoven fabric. The fibers forming the woven or non-woven fabric may be long fibers or short fibers. The fibers forming the woven or non-woven fabric are preferably high modulus fibers. This is because a speaker diaphragm having very excellent strength can be obtained. Representative examples of the high modulus fiber include carbon fiber, polyester fiber, and aramid fiber. Particularly preferred are polyester fibers and aramid fibers. It is because it is excellent in heat resistance.

  Preferably, the high elastic modulus fiber is an untwisted fiber (untwisted fiber). By using non-twisted fibers, the thickness per unit area can be made extremely thin, and as a result, a diaphragm having a light weight and very excellent strength can be obtained.

  Arbitrary appropriate polyester fibers are employ | adopted for the said polyester fiber according to the objective. Polyester fibers have excellent mechanical properties, and are less susceptible to deformation due to moisture absorption and a decrease in elastic modulus even after molding. Specific examples include polyethylene terephthalate (PET) fiber, polybutylene terephthalate (PBT) fiber, polyethylene naphthalate (PEN) fiber, and the like. Polyethylene naphthalate (PEN) fibers are preferable. This is because it is particularly excellent in heat resistance.

  Arbitrary appropriate aramid fiber is employ | adopted for the said aramid fiber according to the objective. Specific examples include para-type aramid fibers and meta-type aramid fibers. Para-aramid fibers are preferred. This is because the internal loss of the fiber is large and the strength is excellent.

  Any appropriate carbon fiber may be employed as the carbon fiber depending on the purpose. Carbon fiber is light and has excellent mechanical properties (for example, high specific strength, high specific modulus, etc.) and excellent properties derived from carbon (for example, heat resistance, low coefficient of thermal expansion, etc.). In addition, the structure of the speaker diaphragm can be satisfactorily maintained. Specific examples of the carbon fiber include PAN (polyacrylonitrile) -based carbon fiber or pitch-based carbon fiber. Any appropriate filament number can be selected as the filament number of the carbon fiber. 1000-3000 are preferable.

C. Other Layers The speaker diaphragm of the present invention preferably includes an adhesive layer between the resin layer and the surface material. This is because adhesion between the surface material and the resin layer can be improved, energy can be easily transmitted, and a speaker diaphragm having excellent response can be obtained. Furthermore, by providing the adhesive layer, the rigidity can be improved, and deformation can hardly occur even at a large amplitude. The adhesive layer is preferably formed of a hot melt adhesive. This is because in the foaming step described later, the hot melt adhesive is melted, and adhesion between the surface material and the resin layer can be easily achieved. Examples of the hot melt adhesive include urethane-based, nylon-based, acrylic-based, and ester-based polybutylene terephthalate.

D. Manufacturing Method The speaker diaphragm of the present invention is heat-molded using, for example, a polystyrene molding machine and a foam molding die. Specifically, the surface material is arranged along the inner wall of the mold core (front side) and / or cavity mold (back side), and pre-expanded particles formed of the resin are filled in the mold. To do. Vapor holes are formed in the mold, and foam molding is performed under predetermined foaming conditions. In this way, the speaker diaphragm can be obtained with a small number of steps by arranging the surface material on the mold in advance. When the adhesive layer is provided, a surface material in which an adhesive layer is laminated in advance on the side on which the resin layer is formed is preferably placed in the mold. It is because it is excellent in productivity. Any appropriate shape can be adopted for the foam molding die. By making the mold into a desired shape, for example, a speaker diaphragm integrated with a dust cap and a diaphragm formed with a voice coil fitting portion can be obtained.

  The pre-expanded particles are typically obtained by foaming resin particles containing the resin and a foaming agent. Any appropriate shape may be adopted as the shape of the resin particles. Specific examples include beads, pellets, and spheres. The average particle diameter of the resin particles is preferably 0.5 to 20 mm, more preferably 0.1 to 2 mm. Commercially available products can be used as the resin particles. Specific examples of commercially available products include Kanepal AX and Kanepal Heat Max HM manufactured by Kaneka Corporation.

  The pre-foaming ratio is preferably 1 to 15 times. The desired density, the average bubble diameter and the bubble density can be satisfied by appropriately selecting the average particle diameter of the resin particles, the pre-foaming ratio and the foaming conditions described later.

Arbitrary appropriate conditions can be employ | adopted for the said foaming conditions. The heating medium typically includes steam and / or air. The temperature of the heating medium is preferably 60 to 120 ° C, more preferably 70 to 110 ° C. The pressure of the heating medium is preferably 0.1 to 3.0 kg / cm ² , more preferably 0.5 to 2.0 kg / cm ² . The final foaming ratio is preferably 5 to 40 times, more preferably 10 to 30 times.

  According to another aspect of the present invention, a speaker is provided. The speaker includes the speaker diaphragm formed in a predetermined shape.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further more concretely, this invention is not limited by these Examples. Unless otherwise indicated, parts and percentages in the examples are based on weight.

(Preparation of pre-expanded particles)
Resin particles (styrene-acrylonitrile copolymer, average particle size: 0.1 to 2 mm, trade name: Kanepal AX, manufactured by Kaneka Corporation) were prefoamed five times to obtain prefoamed particles.

(Shaping of speaker diaphragm)
Using a polystyrene molding machine and a foam molding die, heat molding was performed as follows.
First, a polyethylene naphthalate (PEN) woven fabric [surface density: 166 g / m ² , woven density: 17 vertical / inch × horizontal 17 / inch, thread count: 1100 × on the core mold (front side) as a surface material 1100 dtex, plain weave without twist, manufactured by NI Teijin Shoji]. An aramid non-woven fabric [weighing 60 g / m ² , trade name: Technora, manufactured by Teijin] was disposed as a surface material on the cavity mold (back side). Here, a hot-melt adhesive film [trade name: Thermolite “2810”, manufactured by Daicel Finechem Co., Ltd.] having a thickness of 50 μm was laminated on the inner side (the side on which the resin layer is formed) of both surface materials.
Next, the pre-expanded particles obtained above were filled into a cavity mold, heated for 30 seconds with steam at a temperature of 100 ° C. and a pressure of 1.2 kg / cm ² , then cooled, and the diameter was 16 cm and the thickness was 5. A 0 mm speaker diaphragm was obtained.

  A speaker diaphragm having a diameter of 16 cm and a thickness of 5.0 mm was obtained in the same manner as in Example 1 except that the surface material was not disposed in the cavity mold.

Polyethylene naphthalate (PEN) woven fabric [surface density: 166 g / m ² , weaving density: 17 vertical / inch × horizontal 17 / inch, yarn count: 1100 × 1100 dtex A speaker diaphragm having a diameter of 16 cm and a thickness of 5.0 mm was obtained in the same manner as in Example 1, except that no plain weave, manufactured by NI Teijin Shoji Co., Ltd. was disposed.

A speaker vibration with a caliber of 16 cm and a thickness of 5.0 mm is performed in the same manner as in Example 1 except that an aramid nonwoven fabric (weight per unit: 60 g / m ² , trade name: Technora, manufactured by Teijin) is disposed as a surface material on the core mold. I got a plate.

(Comparative Example 1)
A speaker diaphragm having a diameter of 16 cm and a thickness of 5.0 mm was obtained in the same manner as in Example 1 except that the surface material was not disposed in the core mold and the cavity mold.

  The obtained speaker diaphragm was measured for density, Young's modulus (E), and internal loss (tan δ) by ordinary methods. Further, using these values, specific elasticity (E / density) and rigidity (E × thickness cubed) were calculated. The obtained results are shown in Table 1 below.

  As is apparent from Table 1, by providing the surface material, a speaker diaphragm having an excellent Young's modulus and internal loss in a balanced manner can be obtained. Moreover, comparing the results of Examples 1 to 3, it can be seen that the Young's modulus is further improved by providing the surface material on both sides of the resin layer. By providing the surface material, the Young's modulus improved dramatically. As a result, the speaker diaphragms of Examples 1 to 4 were excellent in specific elasticity as compared with the speaker diaphragm of Comparative Example 1.

  The heating dimensional change rate was measured for the obtained speaker diaphragm. In the measurement method, the obtained speaker diaphragm was stored in a thermostat set at each temperature for 168 hours, and then cooled and heat-treated. Several dimensions of the inner and outer diameters before and after this heat treatment were measured, and the heating dimensional change rate was calculated from the formula: (dimension before heat treatment−dimension after heat treatment) / (dimension before heat treatment). The obtained results are shown in Table 2 below.

  As apparent from Table 2, the speaker diaphragm of each example had a smaller heating dimensional change rate than the speaker diaphragm of the comparative example. From this, it can be said that the speaker diaphragm of each example is excellent in heat resistance. Moreover, the speaker diaphragm of each embodiment can effectively suppress malfunction due to heat generation of the voice coil. Usually, the speaker diaphragm and the voice coil are fixed with an adhesive. If the heating dimensional change rate of the speaker diaphragm is large, there is a possibility that the speaker diaphragm peels off from the adhesive due to heat generation of the voice coil, resulting in malfunction.

  The frequency characteristics of the speakers using the speaker diaphragms obtained in Example 1 and Comparative Example 1 were measured. The result of Example 1 is shown in FIG. 1, and the result of Comparative Example 1 is shown in FIG. As is clear from the comparison of the results of FIG. 1 and FIG. 2, the speaker diaphragm of Example 1 has reduced distortion due to its excellent internal loss, and an improvement in sound quality is recognized. Further, since the specific elasticity is high, it can be seen that the high-frequency elongation is superior to the speaker diaphragm of Comparative Example 1.

  The speaker diaphragm of the present invention is lightweight and has an excellent balance between Young's modulus and internal loss, and can be suitably used for speakers of any application (that is, regardless of whether the aperture is small or large). In particular, it can be suitably used for large-diameter speakers.

It is a graph which shows the frequency characteristic of the speaker using the speaker diaphragm of Example 1 of this invention. 6 is a graph showing frequency characteristics of a speaker using the speaker diaphragm of Comparative Example 1.

Claims (7)

Having a surface material on at least one side of the resin layer having a foam structure,
A speaker diaphragm, wherein the surface material includes a woven fabric and / or a nonwoven fabric. The speaker diaphragm according to claim 1, wherein the density is 0.01 to 0.8 g / cm ³ .   The speaker diaphragm according to claim 1 or 2, wherein an average diameter of bubbles in the foam structure of the resin layer is 1 to 500 µm.   The speaker diaphragm according to any one of claims 1 to 3, wherein the resin layer contains a styrene resin.   The speaker diaphragm according to any one of claims 1 to 4, wherein the woven fabric or non-woven fabric constituting the surface material is formed of polyethylene naphthalate fiber and / or aramid fiber.   The speaker diaphragm according to claim 1, further comprising an adhesive layer between the resin layer and the surface material. A speaker comprising the speaker diaphragm according to claim 1.

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