JP2505793Y2 - Speaker dust cap - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a dust cap having high water resistance of a dynamic speaker.

<Prior Art> Conventionally, the dust cap (oa) of this type of speaker is located at the center of the cone-shaped diaphragm (od) as shown in FIG. It vibrates following the vibration displacement of (above), has the function of blocking magnetic substances such as iron powder and dust, and preventing foreign matter from entering the magnetic gap, and is lightweight and reasonably breathable. Alternatively, in some cases, the sealing property and the flexibility are required, and further, the suppression force of resonance of the vibration system including the vibration plate (od) and the relatively large vibration absorption force are also required.

Generally, the value of tan δ (vibration loss rate) that suppresses the self-resonance of the dust cap as much as possible is often 0.06 to 0.1 or more. These physical properties do not change due to moisture or heat, and it is necessary to keep the values at the time of initial design for a long period of time, and water resistance is required especially for special applications such as automobiles or outdoors.

As a dust cap (oa) for the diaphragm (od) that meets these requirements, a cotton woven fabric impregnated or coated with a resin with a large vibration absorbing force such as acrylic resin is heated and pressed into a dome shape or a flat plate shape. Many of them are used.

<Problems to be solved by the invention> Therefore, the conventional coating resin of this kind of dust cap (oa) has insufficient water resistance, and moisture permeates into the cotton fabric constituent base material and the coating material, and When the components are softened, deformed, or installed in the speaker,
There is a problem in that performance defects often occur such as abnormal resonance in the diaphragm divided vibration band, rubbing of the magnetic gap of the voice coil, fluctuation of the minimum resonance frequency, and damping change in the low range.

Therefore, conventionally, a dust cap (oa) coated with a fluororesin having high water resistance has been proposed, but since the dust cap does not have sufficient adhesive strength, it is difficult to adhere to the diaphragm (od), and tanδ If the value is about 0.3 or less, the vibration absorbing force is small and not suitable for practical use.

SUMMARY OF THE INVENTION In order to solve the conventional problems, an object of the present invention is to provide a dust cap for a speaker, which has a large adhesive force and is highly water resistant.

<Means for Solving the Problems> The structure of the present invention for achieving the object will be described with reference to FIGS. 1 to 5 corresponding to the embodiments. ) Is impregnated with a phenol resin solution having a concentration of 20% and dried to prepare a base coating material (g), and the self-supporting force is maintained.

Next, an emulsion of butyl acrylate (A) which is an acrylic resin as a vibration absorbing material is added to the above coating material (g),
As a water resistant material, a liquid (C) prepared by mixing an emulsion of a fluororesin (B) is coated with a knife coater to give about 13
After heating and drying at 0 ° C. for 3 minutes, the dome-shaped dust cap (a) of the present invention is formed by further heating and molding with a heating dome-shaped mold at about 210 ° C. for 15 seconds.

Further, the coated cloth (g) is coated with an acrylic vibration absorbing material (A), dried, and then a mixed solution (C) of an emulsion of the acrylic resin (A) and the fluororesin (B) thereon.
After coating and drying at about 130 ℃ for 3 minutes,
Further, it is heated and molded in a dome-shaped mold at about 210 ° C. to obtain the dust cap (b) of the present invention.

<Operation> In the structure of the dust cap of the present invention, since the surface is formed by the mixture of the vibration absorbing resin and the fluororesin as described above, the presence of the fluororesin reduces the tanδ value and the adhesiveness of the vibration absorbing resin. It has become possible to obtain a large amount of water repellency in the dust cap (a, b) of the speaker without significantly reducing it. Also, the dust cap of the present invention is
With the above structure, moisture does not penetrate into the constituent material (G) to deform or soften the constituent material, due to the change of the low frequency range frequency characteristic and the fluctuation of the vibration absorption power of the dust cap, It has an excellent effect that changes in high frequency range characteristics and abnormal resonance in divided vibration bands do not occur. Moreover, since the mold release property from the mold is good at the time of manufacturing, a mold release material is not required, which has occurred conventionally. It is a dust cap that is free from defects due to uneven coating of the release material, has stable quality, and is highly producible in mass production.

<Embodiment> An embodiment of the present invention will be described below with reference to the drawings.

FIGS. 1 to 5 are views showing an embodiment of the present invention. In this embodiment, for example, a cotton fabric base material (G) is impregnated with a phenol resin solution having a concentration of 20% and dried to form a base. The following coating material (g) is prepared, and the self-sustaining shape retention force is maintained together with the filling.

Next, an emulsion of butyl acrylate (A) which is an acrylic resin as a vibration absorbing material is added to the above coating material (g),
As a water resistant material, a liquid (C) prepared by mixing an emulsion of a fluororesin (B) is coated with a knife coater to give about 13
After being dried by heating at 0 ° C. for 3 minutes, it is further heat-molded by a heating dome-shaped mold at about 210 ° C. for 15 seconds to form the dust cap (a) of the present invention.

The coated cloth (g) is coated with an acrylic vibration absorbing material (A), dried, and then a mixed solution (C) of an emulsion of the acrylic resin (A) and the fluororesin (B) thereon.
To obtain the dust cap (b) of the present invention. (Figs. 1 and 2) When comparing the water resistance of these dust caps (a, b) by measuring the contact angle of water on the surface of the coated cloth (g),
As shown in the contact angle table of FIG. 3, the tensile strength table of FIG. 4, and the tan δ table of FIG. 5, respectively, the vibration loss rate (tan δ) and the practical adhesiveness do not decrease, and the water repellency is Strengthens and increases water resistance. (FIGS. 3, 4, 5) In the dust cap of the present invention, the ratio of the fluororesin to the vibration-absorbent resin is preferably in the range of 3 to 12%. If it is less than 3%, the water-repellent effect is insufficient, and if it is more than 12%, the adhesive strength may decrease in some cases, making it impractical.

Further, the vibration absorbing resin and the fluorine resin may be mixed in a state of a solution with an organic solvent, other than the method of the above-described embodiment in which the resin is mixed in the state of an emulsion.

In each of the above embodiments, the dust cap (a)
Since the coating layer is a single layer, it is inexpensive and excellent in mass productivity. Since the dust cap (b) has a vibration absorbing resin layer inside, it has a large tan δ value and an excellent vibration absorbing ability.

Although the embodiments considered to be typical of the present invention have been described above, the present invention is not necessarily limited to only the structures of these embodiments, and the constitutional requirements referred to in the present invention and the purpose referred to in the present invention can be obtained. The present invention can be carried out with appropriate modifications within the scope of achieving the following effects.

<Effect of the invention> As is clear from the above description, the structure of the invention is
Since the surface is made of a mixture of vibration absorbing resin and fluororesin, it is expected to have a significant practical effect that the tan δ value and the adhesiveness will not be reduced and a large water repellency will be obtained in the speaker dust cap. It has come to be possible.

In addition, the dust cap (a, b) of the present invention has a structure that allows water to permeate into the cotton fabric base material and the coating material to soften and deform these components and to be incorporated into the speaker. If so, the abnormal resonance in the diaphragm divided vibration band,
The voice coil also has the excellent effect that there is no performance defect such as magnetic air gap rubbing, fluctuation of the minimum resonance frequency, damping change in the low range, etc. Moreover, since the mold release property is good at the time of manufacturing, the mold release material is It is not necessary, and the occurrence of defects due to uneven coating of the release material that has occurred in the past is eliminated, so that the quality is stable and it is rich in mass production.

[Brief description of drawings]

FIG. 1 is a sectional view of the dust cap of the speaker of the present invention,
2 (a) and 2 (b) are the same cross-sectional model views, FIG. 3 is a table of measured values of the same contact angle, FIG. 4 is a table of measured values of the same adhesive force (tensile strength), and FIG. FIG. 6 is a cross-sectional view of the conventional example, which is a table of values of tan δ. In the figure, (A) is an acrylic resin, (B) is a fluororesin,
(C) is an emulsion mixture, (a) and (b) are the dust caps of the present invention, (G) is a cotton fabric base material, and (g) is
Is a coating material impregnated with phenol resin.

Claims (1)

(57) [Scope of utility model registration request] 1. A speaker dust cap in which the surface of a constituent base material (G) is formed of a mixture (C) of a vibration absorbing resin (A) and a fluororesin (B).