JPH078078B2 - 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. 5, the structure of a general dynamic speaker is such that a diaphragm (26) is placed in an annular magnetic gap (29a) formed by a magnetic circuit (29) incorporating a magnet (30). ) Suspend the voice coil (28) attached to the end of
The edge (3) attached to the outer edge of the damper (31) and the diaphragm (26)
It is supported by the frame (27) at 5). Then, in the vicinity of the base of the voice coil (28) on the upper surface of the diaphragm (26), attach a dome-shaped dust cap (25) concentrically,
The annular magnetic gap (29a) is covered to protect foreign matters such as iron powder from entering. Therefore, the vibrating plate (26) vibrates integrally with the dust cap (25) and acts as an additional mass in terms of vibration. And the vibration of the diaphragm (26) is
Directly transmitted to the dust cap (25), the dust cap (2
5) Noise is generated by itself, and the vibration of the dust cap (25) is reflected back to the diaphragm (26) and interferes with or suppresses the vibration of the diaphragm (26). The dust cap (25) not only protects foreign substances from mixing in from the outside, but also greatly affects the reproduction sound quality of the speaker.

That is, the dust cap (25) is a diaphragm (2
Since it is located at the center of 6), it has a great influence on the sound pressure frequency characteristics especially in the high frequency range, and those that are qualitatively hard and have a small vibration loss rate have peaks and dips in the high frequency range of the reproduced sound pressure frequency characteristics. Is large, it is required to have a large vibration absorbing effect in order to prevent it. Also, dust cap
Since (25) vibrates integrally with the diaphragm (26), a function to assist the diaphragm (26) as an acoustic radiator is desired.
As with (26), it is naturally required to be lightweight and highly rigid.

Conventionally, a dust cap of this type of speaker has a woven fabric base made of a thermoplastic fiber such as cotton fabric or polyester impregnated with a phenol resin (04) as a shape-imparting material and a hardness adjusting material as shown in the cross section of FIG. The material (01) is coated with acrylic resin as a vibration absorbing material and sealing material (03), and is heated and pressure molded into a dome shape (conventional example
(I)), or a sheet of thermoplastic resin or elastomer resin such as polypropylene or polyurethane,
Heated and pressed to form a dome shape (conventional example (II))
(Not shown) or the like is used.

[0005]

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 one of the above-mentioned (conventional example (I)) uses the hardness adjusting material, so that the desired stiffness can be easily obtained. Therefore, it is versatile and widely used, but when the base material is cotton yarn, it has high hygroscopicity and is therefore easily deformed by moisture, and those using a thermoplastic synthetic fiber fabric such as polyester fiber fabric for the base material are Since it is easily deformed by heat, when used in an atmosphere where moisture resistance and heat resistance are required for automobiles, ships, etc., it causes abnormal natural vibration due to deformation of the dust cap itself, and also
There is a problem that there is a defect that often causes abnormal noise or distorted noise due to deformation of the diaphragm.

In the dust cap such as the latter (conventional example (II)), the hardness can be adjusted to some extent by the filler, but the fluidity of the material deteriorates during sheet production by extrusion molding or the like. Therefore, there is a limit in the amount of mixing naturally, so that there is a drawback that the hardness adjustment range is small and the speaker design is limited.

The latter has a lower heat distortion temperature than the former and has various problems in applications other than household use, and even in household use, it is deformed by heat conducted from the voice coil and bobbin at the time of large input. However, there are drawbacks such as the frequency characteristics changing due to softening.

In order to compensate for these drawbacks, in the former case, in order to impart rigidity, the resin content of the woven fabric is increased to make it harder, and in the latter case, a hardening agent is used to enhance the hardening. All of these have the bad result of increasing the high frequency peaks and dips of the frequency characteristics. Further, in order to prevent such a bad result from appearing, it is necessary to take measures such as increasing the amount of the vibration absorbing material in the former case and increasing the thickness in the latter case. Therefore, the present invention, in order to solve the problems of the above-mentioned conventional examples (I), (II), the surface side (1a) of the fiber woven fabric base material (1) is coated with a vibration absorbing resin (2). , The back surface side (1b) is coated with a heat-sealable adhesive (3) that also serves as a vibration absorbing material, and the two adhesive side surfaces (1b, 1b) of the two textile fabric base materials (10) are made to face each other, In the meantime, another woven fabric (40) containing an air layer (4) inside is placed on top of each other, heat-press bonded and a dome-shaped cross section with air inside. Provided is a speaker dust cap capable of suppressing generation of abnormal sound and distorted sound due to abnormal natural vibration for the purpose of improving water resistance, heat resistance and deformation resistance by adopting a three-layer structure. To do.

[0010]

The structure of the present invention for achieving the object will be described with reference to FIG. 1 corresponding to an embodiment. The present invention is based on the surface side of a textile fabric base cloth (1). Adhesion of two fibrous fabric base materials (10), each of which is formed by coating the vibration absorbing resin (2) on (1a) and the heat-sealable adhesive (3) that also functions as a vibration absorbing material on the back side (1b). The agent surfaces (1b, 1b) are made to face each other, and another fiber woven fabric (40) that has been processed to incorporate the air layer (4) inside is sandwiched between them, and they are laminated by heat and pressure. , It is a speaker dust cap that is molded under the condition that it contains air inside.

[0011]

According to the present invention, air having such a built-in air is used.
Since it has a layered structure, the density can be reduced and the weight can be reduced, so the Young's modulus is slightly reduced, but the thickness can be increased, so it is expressed by [Young's modulus x thickness ³ ] As the rigidity increases, deformation of the dust cap and deformation of the vibration plate due to deformation force are prevented, sufficient shape retention is maintained, abnormal noise and distortion noise can be suppressed, and 1.35 Fiber woven fabric substrate (10) coated with vibration absorbing material / adhesive (3) with high material vibration loss rate
In addition, the vibration loss rate (tan δ) of the dust cap can be kept large by the action of the air (4) embedded in the other fiber fabric (40) of the core material, and the vibration energy absorption action allows the dust cap itself to have an unusual characteristic. Vibration can be suppressed, and by this, the peak of the high frequency range of the sound pressure frequency characteristics of the speaker,
The dip can be improved.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. Fig. 1 shows that as a core material consisting of warp and weft, a fiber woven base fabric (5) is made of cotton fabric of, for example, 73.5 g / m ² and impregnated with a shaping agent of a methanol solution of phenol resin having a resin concentration of 10%. And obtained by drying with hot air, 82.5 g /
m ^{2 is} a 200 micron thick fibrous woven base fabric (40) with a portion of the texture holes shown in FIG. 2 forming voids.
Further, a polyester fiber woven cloth of 50 g / m ² and a thickness of 65 μm is adopted as the fiber woven base cloth (1), and its surface (1a) is
The back surface (1b) of the intermediate product cloth having a thickness of 67.5 g / m ² and a thickness of 85 μm, which was obtained by coating an acrylic resin emulsion as the vibration absorbing material (2) and drying with hot air, was mainly composed of ethylene vinyl acetate resin. , Heat-sealing adhesive that doubles as a vibration absorber
The emulsion of (3) was coated and dried with hot air to obtain a fiber woven substrate (78 g / m ² , 106 micron thick) (1
I got 0).

Two fiber fabric substrates (10,10) as described above
Of the adhesive, the adhesive surfaces (1b, 1b) are opposed to each other, and another fiber woven base material fabric (40) having the air layer (4) is sandwiched between them and stacked. Then, heat and pressure molding with a mold of about 200 ° C., and a fiber woven fabric substrate as shown in FIG.
A dome-shaped dust cap with a diameter of 95 mm was obtained with a three-layer structure in which (40) was used as the core material and the fiber woven fabric substrate (10, 10) was bonded to both sides, and it was mounted on a cone-shaped diaphragm with an outer diameter of 25 cm. Frequency characteristics were measured (Fig. 4), and the flange was cut off to determine Young's modulus and thickness at 115 ° C.
The result of measuring the heat and moisture resistance deformation degree at 42 ° C. and 95% RH is shown as A in Table 1.

Next, as a conventional example to be compared, 135 g
151 g of a cotton fabric of 1 g / m ² was treated in the same manner as above.
/ M ² , a phenol-impregnated base material with a thickness of 280 μm is obtained, and a vibration-absorbing coated cloth with a surface of 231 g / m ² and a thickness of 300 μm coated with an acrylic resin vibration-absorbing material is obtained, and heated and pressed. Then, the dust cap shown in B of Table 1 was obtained and compared with A, the result as shown in Table 1 was obtained.

Although the examples considered to be typical of the present invention have been described above, the present invention is not necessarily limited to the structures of these examples, and has the above-mentioned constitutional requirements referred to in the present invention, and The present invention can be carried out by appropriately modifying it within a range that achieves the object of the present invention and has the following effects.

[0016]

According to the speaker dust cap of the present invention, the hollow air layer (4) is built in the texture hole of the fiber woven fabric base material (40) of the core material as shown in FIG. As shown in FIG. 4, the Young's modulus is slightly lower than the conventional examples (I) and (II), but the rigidity is large and the vibration loss ratio is large, as shown in FIG. In contrast to the dotted line curve of the conventional example, as shown by the solid line, there can be no expectation for the conventional one that there are few peaks and dips in the high frequency range of the high frequency range and there is no deformation due to humidity or heat. It came to have a remarkable effect.

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. Moreover, since the selection range for the curing by the filler can be widened, it is possible to expect an effect that the degree of hardness adjustment is wide and the versatility is expanded.

[Brief description of drawings]

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

FIG. 2 is an exploded view of the configuration of FIG.

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

FIG. 4 is a diagram comparing sound pressure frequency characteristics of a speaker of the present invention and a speaker of a conventional example.

FIG. 5 is a cross-sectional view of a dynamic speaker.

[Explanation of symbols]

 (1) Fiber fabric base fabric (10) Fiber fabric base (1a) Front side (1b) Back side (2) Vibration absorbing resin (3) Vibration absorbing / adhesive (4) Air layer (5) Different core materials Fiber woven fabric base fabric (40) Fiber woven fabric impregnated with a shaping material and a built-in air layer

[Table 1]

Claims (1)

[Claims] 1. A fiber woven base fabric (1) is coated with a vibration absorbing resin (2) on the front side (1a) and a back side (1b) is coated with a heat-sealable adhesive (3) also serving as a vibration absorbing material. Of the two fibrous fabric base materials (10) each of which is formed by making the adhesive surfaces face (1b, 1b) face each other, and another fibrous fabric processed so that the air layer (4) is built in the space between them. A speaker dust cap with a structure in which (40) is stacked on top of each other, heat and pressure bonded, and molded with air (4) inside.