JPH078077B2 - Speaker dust cap - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dust cap for a speaker, which is mainly composed of a fiber woven fabric and a vibration absorbing material, is stable against moisture and heat, has little deformation, is lightweight, and has high input resistance.

[0002]

2. Description of the Related Art As shown in FIG. 4, the structure of a general dynamic speaker is such that a diaphragm is placed in an annular magnetic gap (9a) formed by a magnetic circuit (9) incorporating a magnet (10).
The voice coil (8) attached to the tip of (6) is suspended and supported by the frame (7) by the damper (11) and the edge (15) attached to the outer edge of the diaphragm (6). Then, the diaphragm (6)
Attach a dome-shaped dust cap (5) near the root of the voice coil (8) on the upper surface of the to cover the annular magnetic gap (9a) and prevent foreign substances such as iron powder from entering. Protect. Therefore, the diaphragm (6) will
It vibrates integrally with and acts as an additional mass in terms of vibration. And the vibration of the diaphragm (6) is directly dust-capped.
The noise is generated in the dust cap (5) itself by being transmitted to (5), or the vibration of the dust cap (5) is reflected back to the diaphragm (6) and interferes with the vibration of the diaphragm (6). The dust cap (5) of the speaker largely affects not only the protection of foreign matters but also the reproduced sound quality of the speaker because it is controlled or suppressed. Therefore, the dust cap (5)
A function of assisting the diaphragm (6) as an acoustic radiator is desired, which is integrated with (6). Conventionally, this type of speaker dust cap has a cotton fabric base material (01) impregnated with a phenolic resin (04) impregnated with a vibration absorbing material (03) on its surface, as shown in the cross section of FIG. Heat-pressed dome-shaped
(Conventional example (I)), or a polypropylene sheet vacuum-formed into a dome shape (conventional example (II)) (not shown) is used.

[0003]

These conventional speaker dust caps are deformed when heat generated from the voice coil is transmitted when a material having good heat conduction such as carbon fiber or aluminum sheet is used for the diaphragm. Therefore, heat resistance is required because there is an adverse effect such as void defect.
Therefore, in the above-mentioned conventional dust cap of this type of speaker, the former (conventional example (I)) of the above is a cotton thread having a large hygroscopic property, and is a methyl alcohol having a solubility parameter similar to that of water. Dissolved phenolic resin (04)
Since the liquid easily penetrates the fabric (01) and the penetration and impregnation are easily saturated to a certain amount by dipping for a few seconds, just by selecting the concentration of the phenolic resin (04) in the solution, stable hardness adjustment can be achieved. As the material and the shape-imparting material, the hardness can be selected according to the purpose, and the versatility in the design of the speaker is wide, and thus it is commonly used.

However, since the cotton fabric (01) and the phenol resin (04) both have a large amount of moisture absorption and have a large expansion amount when they absorb moisture, other heterogeneous materials having a small amount of moisture absorption and therefore a small amount of expansion due to humidity. If a two-layer structure with a vibration absorbing material such as acrylic resin, butyl rubber, etc. is used, the amount of deformation due to humidity is large, and when used in an atmosphere with a lot of moisture such as for automobiles, the abnormal characteristic vibration of the dust cap itself However, there is a problem in that it often causes an abnormal sound or a distorted sound such as deformation of the diaphragm caused by the deformation force of the dust cap.

In the dust cap such as the latter (conventional example (II)), the amount of deformation due to moisture absorption is small, but soft deformation due to heat is likely to occur and heat resistance is required for the automobile. When used in a speaker or a speaker with a carbon fiber diaphragm that easily conducts heat from a voice coil bobbin such as a loudspeaker or a speaker with a large output, thermal deformation easily occurs due to the conducted heat, which causes abnormal noise. However, the hardness cannot be made lower than that of the polypropylene resin, and the curing by the filler is limited, so that there is a drawback that the versatility of hardness selection is low.

Therefore, in order to solve the problems of the conventional dust caps (I) and (II), the present invention provides the surface side (1a) of the fiber woven fabric substrate (1). The back side of the base cloth (1) coated with the vibration absorbing material (2) and the back side (1b) coated with the heat-sealable adhesive (3) also serving as the vibration absorbing material containing ethylene vinyl acetate as the main component (3). The adhesive (3) surface of 1b) is bonded and molded to improve water resistance, heat resistance and deformation resistance. The present invention provides a dust cap for a speaker that can suppress the generation.

[0007]

The structure of the present invention for achieving the object will be described with reference to FIG. 1 corresponding to an embodiment. Two bases coated with vibration-absorbing material (2) on 1a) and coated on the back side (1b) with a heat-fusion adhesive (3) that also functions as a vibration-absorbing material containing ethylene vinyl acetate as a main component. A dust cap for a speaker having a structure in which an adhesive (3) surface of a back surface side (1b) of a material cloth (1) is overlapped and molded.

[0008]

According to the present invention, since two cloths having good water resistance and heat resistance are laminated vertically symmetrically, it is possible to cancel the difference in expansion coefficient from each other. It prevents deformation and deformation of the diaphragm due to deformation force, has sufficient shape retention, can suppress the generation of abnormal noise and distortion noise, and can absorb dust energy by vibrating energy absorption function of the vibration absorbing material (2). It is possible to suppress the abnormal natural vibration of itself, thereby improving the frequency characteristic in the high frequency range.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. Figure 1 shows a textile fabric base made of warp and weft (1) For example, cotton fabric and methanol of phenolic resin 15
Impregnated with a solution of 100% concentration and dried with hot air,
In b), a hot-melt adhesive (3) consisting of a copolymer emulsion of about 80% ethylene vinyl acetate and about 20% acrylic for improving heat resistance is applied and coated, and dried with hot air. The dust cap of the speaker (A) constructed by sticking the back surface (1b) side adhesive surface of each of the two cloth materials obtained by
Is shown.

The dust cap (A) thus obtained
Was left in an atmosphere of 42 ° C. and a relative humidity of 95% and a dry atmosphere of 115 ° C. for 1 hour and 96 hours, respectively, and the vibration loss rate was measured to measure Fiber cloth base material (1) consisting of, for example, cotton cloth impregnated with a solution of phenol resin in 35% methanol (2 '), and a vibration absorbing material (3') consisting of acrylic emulsion is dried with hot air and heated and pressed. Dust cap just molded
(B) (corresponding to (I) of the conventional example, a cross section is shown in FIG. 2), and the result of comparing the dust cap (C) corresponding to (II) of the conventional example after performing the same environmental treatment as above. Is shown in Table 1. The examples considered to be typical of the present invention have been described above.
The present invention is not necessarily limited to only these example structures, and includes the above-mentioned structural requirements referred to in the present invention, and achieves the object referred to in the present invention, within the scope of having the effects described below. It can be modified and implemented.

[0011]

According to the speaker dust cap of the present invention, with the above-mentioned constitution, the surface of the textile fabric base material is coated with the acrylic resin vibration absorbing material, and the back surface side thereof is coated with ethylene vinyl acetate as a main component. Thermo-compression type adhesive that doubles as a material is overlaid and molded,
Since it is a speaker dust cap composed by laminating two sheets symmetrically, it is possible to cancel the influence of the expansion of the two cloth bodies to each other, so that the deformation of the diaphragm due to the deformation force of the dust cap is prevented, and an abnormal condition occurs. You can suppress the generation of sound and distorted sound,
As a result, it is possible to suppress the generation of abnormal noises and distorted noises due to the abnormal natural vibration of the dust cap itself, while suppressing the significant resonance due to the action of the vibration absorbing material, improving the frequency characteristics in the high frequency range. Has had significant effects that cannot be expected.

Therefore, the present invention has a small amount of hygroscopic deformation, is less likely to be softened and deformed by heat, and is required to have heat resistance and moisture resistance in a use state. It is used for a speaker of a carbon fiber diaphragm that easily conducts heat from the coil bobbin, and does not cause thermal deformation due to the conducted heat and does not cause abnormal sound. Also, it is easy to select the hardness below the polypropylene resin, and the selection range for curing with a filler can be widened.
It has come to be possible to expect an effect that the versatility can be improved.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing a configuration of an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view showing a configuration of a conventional example for comparison.

FIG. 3 is a schematic cross-sectional view showing the configuration of a conventional example.

FIG. 4 is a cross-sectional view of a dynamic speaker.

[Explanation of symbols]

 (1) Fiber woven fabric substrate (1a) Front side (1b) Back side (2) Vibration absorber (3) Adhesive

[Table 1]

Claims (1)

[Claims] 1. A vibration absorbing material on the surface side (1a) of a textile fabric base material (1).
(2) is coated, and the back side (1b) is a heat-fusion adhesive that also functions as a vibration absorber with ethylene vinyl acetate as the main component.
A speaker dust cap having a structure in which two base material cloths (1) coated with (3) are formed by superposing the adhesive (3) surfaces on the back side (1b) of each.