JP3943218B2 - Diaphragm for electroacoustic transducer - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a diaphragm for an electroacoustic transducer that includes a diaphragm main body and an edge made of a material different from that of the diaphragm main body.
[0002]
[Prior art]
The physical properties required of diaphragms for electroacoustic transducers such as speakers are large in specific elastic modulus (E / ρ; E: Young's modulus, ρ: specific gravity) and specific bending rigidity (E / ρ ³ ). It has loss, is resistant to mechanical fatigue, and has good weather resistance.
[0003]
In particular, a free-edge diaphragm 3 using a diaphragm main body 1 as shown in FIG. 7 mainly composed of natural fibers and an edge 2 based on urethane foam or woven fabric is used as a diaphragm. Compared to those using synthetic resin and metal for the main body 1 and those using vulcanized rubber and thermoplastic elastomer for the edge 2, it is superior in terms of light weight, freedom of design, cost and the like.
[0004]
On the other hand, in recent years, waterproofness has become an important characteristic mainly for in-vehicle speakers.
However, since the above-described free edge diaphragm 13 is not waterproof, the following proposals have been made to provide waterproofness.
[0005]
(1) A method of impregnating the free edge diaphragm 3 with a highly waterproof resin.
(2) As shown in FIG. 8 (a), in order to provide waterproofing from the direction of the arrow A, film layers 3 and 4 are formed by heat-bonding or adsorbing synthetic resin films to the diaphragm body 1 and the edge 2, respectively. After that, the diaphragm main body 1 and the edge 2 are bonded together.
[0006]
As shown in FIG. 8 (b), in order to provide waterproofing from the direction of arrow B, film layers 3 and 4 are formed by thermocompression bonding or heat adsorption on the diaphragm main body 1 and the edge 2 respectively. Then, the method of bonding the diaphragm main body 1 and the edge 2.
[0007]
However, in the method (1) of impregnating the free edge diaphragm 3 with a highly waterproof resin, the resin to be impregnated is silicone, wax, or fluorine, and the adhesion in the subsequent assembly process is excluded. There are problems such as.
[0008]
Further, in the method (2) in which a film layer is formed on the diaphragm main body 1 and the edge 2 and then the diaphragm main body 1 and the edge 2 are bonded, a film is formed on the end surface 2a of the edge 2 in FIG. Since there is no layer, and there is no film layer on the end face 1a of the diaphragm main body 1 in FIG. 8 (b), there is a problem that water enters from these end faces 1a and 2a.
[0009]
Therefore, in Japanese Patent Laid-Open No. 6-78393, as shown in FIG. 9, after the diaphragm main body 1 and the edge 2 are bonded, a synthetic resin film is thermocompression-bonded or thermally adsorbed over the entire diaphragm. 5 is described.
[0010]
By setting it as such a structure, the penetration | invasion of the water from the diaphragm main body 1 or the end surfaces 1a and 2a of the edge 2 can be prevented.
[0011]
[Problems to be solved by the invention]
However, in the diaphragm having the configuration shown in FIG. 9, when the film layer 5 is formed using a thin film, if the material of the edge 2 is a porous material such as urethane foam, the degree of softening of the film and the degree of pressure Therefore, there is a problem that pinholes are generated in the film layer 5 and the waterproof property is lowered.
[0012]
On the contrary, when the film layer 5 is formed using a thick film, the edge 2 which is less rigid than the diaphragm main body 1 is caused by the shrinkage of the film generated when the film layer is formed or the relaxation of the residual stress in each environment. There is also a problem that it is pulled and deformed greatly.
[0013]
Furthermore, if the hardness of the film is low, there is a problem that the film rigidity is lowered and the workability is poor.
Further, if the film does not have heat resistance, there is a problem that when the film is left for a long time at a high temperature, the film soaks into the diaphragm main body 1 and the edge 2 which are base materials, and the waterproofness is lowered.
[0014]
Furthermore, in the case of a film in which both the heat resistance and hardness of the film are too high, there is a problem of excluding moldability and adhesiveness.
The present invention has been made in view of the above problems, and a first object thereof is to provide an appropriate thickness of a film layer provided over the entire area of the diaphragm.
[0015]
A second object of the present invention is to provide an appropriate material for the film layer provided over the entire area of the diaphragm.
[0016]
[Means for Solving the Problems]
The invention according to claim 1, which solves the above-mentioned problem, is a diaphragm for an electroacoustic transducer, comprising a diaphragm body and an edge made of a material different from that of the diaphragm body. , A synthetic resin film layer having a thickness of 25 to 45 μm is provided over the entire area of at least one surface of the diaphragm for the electroacoustic transducer , and the synthetic resin film layer includes a monocarboxylic acid, a dicarboxylic acid, a dicarboxylic acid anhydride, and their A diaphragm for an electroacoustic transducer, characterized by being made of a material obtained by blending 1 % to 40 % by weight of polyethylene with an ethylene copolymer resin containing a metal chloride .
[0017]
After bonding the diaphragm main body and the edge, the synthetic resin film layer is formed over the entire area of the diaphragm, so that the edge shape retainability is improved and deformation is suppressed compared to the case where the film layer is formed on the edge alone. Can do.
[0018]
Further, since the end face of the edge and the end face of the diaphragm main body are also covered with the synthetic resin film layer, water does not enter from the end face and the waterproofness is improved.
Furthermore, since the synthetic resin film layer is formed in one step, the cost can be reduced as compared with the case where the film layer is formed on the diaphragm main body and the edge.
[0019]
Furthermore, by making the thickness of the synthetic resin film layer 25 to 45 μm, it is possible to obtain a diaphragm for an electroacoustic transducer with little deformation and excellent waterproofness .
[0020]
The synthetic resin film layer is made of a material obtained by blending 1% to 40% by weight of polyethylene with an ethylene copolymer resin containing monocarboxylic acid, dicarboxylic acid, dicarboxylic acid anhydride and their metal chlorides. Waterproofness, little deformation due to temperature change, high heat resistance, and good workability can be obtained.
[0021]
In particular, according to the present invention, it can be used for dust cones, subcones and tweeters that are particularly susceptible to deformation and whose mass increase greatly affects performance, and a great effect is obtained.
[0022]
Examples of those containing monocarboxylic acid include ethylene / acrylic acid and ethylene / methacrylic acid.
Examples of those containing dicarboxylic acid include ethylene, ethyl acrylate, and maleic acid.
[0023]
Examples of dicarboxylic acid anhydrides include ethylene, ethyl acrylate, and maleic anhydride.
These metal chlorides include ethylene / methacrylic acid, methacrylic acid metal salts, ethylene / ethyl acrylate / maleic acid metal salts, and the like.
[0024]
Also included are polyethylene, ethylene / vinyl acetate copolymer, and ethylene / methyl methacrylate copolymer which are later graft copolymerized with acrylic acid, maleic anhydride and the like.
[0025]
According to a second aspect of the invention, the synthetic resin film layer of the invention of claim 1 Symbol placement is heated and pressed, electroacoustic transducer diaphragm, characterized in that it is formed by either of the methods of heating the adsorption It is.
[0026]
By forming the synthetic resin film layer by either one of thermocompression bonding and heat adsorption, a synthetic resin film layer having an easy and uniform thickness can be formed.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings. In this embodiment, a description will be given using a free edge diaphragm for a speaker as the diaphragm for an electroacoustic transducer.
[0028]
FIG. 1 is a cross-sectional view of a free edge diaphragm according to an embodiment of the present invention. In the figure, the free edge diaphragm 13 includes a diaphragm main body 11 and an edge 12 bonded to an outer edge portion of the diaphragm main body 11.
[0029]
A synthetic resin film layer 15 having a thickness of 25 to 45 μm is formed over the entire back surface of the free edge diaphragm 13.
Next, a method for manufacturing the free edge diaphragm 13 having the above configuration will be described.
[0030]
(1) Ethylene / ethyl acrylic coat / maleic anhydride terpolymer resin is blended with 30% by weight of polyethylene, and a synthetic resin film 20 having a thickness of about 35 μm is manufactured by extrusion molding.
[0031]
(2) NBKP (coniferous bleached kraft pulp) is made into a predetermined shape by a wet papermaking method, press-dried, punched into a predetermined size, and the diaphragm main body 11 is manufactured. The mass of the diaphragm main body 11 of the present embodiment is about 1.4 g.
[0032]
(3) An ether-based urethane foam is press-molded into a predetermined shape and punched to a predetermined dimension to produce the edge 12.
(4) The diaphragm main body 11 and the edge 12 are bonded to each other with a rubber adhesive to manufacture the free edge diaphragm 13.
[0033]
Thereafter, the apparatus shown in FIG. 2 is used. In the figure, reference numeral 27 denotes a diaphragm receiving jig on which the free edge diaphragm 13 is placed. A plurality of suction pipes 26 are formed between the surface of the diaphragm receiving jig 27 on which the free edge diaphragm 13 is placed and the chamber 25 formed in the lower part. The air in the chamber 25 and the suction pipe line 26 is sucked through the suction hole 28 by a suction pump (not shown).
[0034]
On the diaphragm receiving jig 27, a clamp 24 that holds the synthetic resin film 20 and can approach / separate from the diaphragm receiving jig 27 is provided. A far infrared heater 29 is provided on the clamp 24 and heats the synthetic resin film 20.
[0035]
(5) Place the free edge diaphragm 13 on the diaphragm receiving jig 27.
(6) Set the synthetic resin film 20 on the clamp 24.
(7) Energize the far infrared heater 29 and heat the synthetic resin film 20 for about 4 seconds to soften it.
[0036]
(8) Using the clamp 24, the synthetic resin film 20 is moved onto the free edge diaphragm 13, and the air in the chamber 25 of the diaphragm receiving jig 27 and the suction pipe 26 is sucked into the suction hole 28 by a vacuum pump (not shown). The synthetic resin film 20 is brought into close contact with the back surface of the free edge diaphragm 13.
[0037]
(9) In order to firmly attach the synthetic resin film 20 to the free edge diaphragm 13, after the vacuum suction is stopped, the synthetic resin film 20 is heated by the far infrared heater 29 for about 20 seconds to be synthesized on the back surface of the free edge diaphragm 13. A resin film layer 15 is formed.
[0038]
(10) Punch out the inner and outer diameters of the free edge diaphragm 13 to predetermined dimensions.
According to the above configuration, when the diaphragm main body 11 and the edge 12 are bonded, and the synthetic resin film layer 15 is formed over the entire back surface of the free edge diaphragm 13, the film layer is formed on the edge 12 alone. Compared to the above, the shape retention of the edge 12 is improved, and deformation can be suppressed.
[0039]
Further, since the end face of the edge 12 and the end face of the diaphragm main body 11 are also covered with the synthetic resin film layer 15, water does not enter from the end face and the waterproofness is improved.
Furthermore, since the synthetic resin film layer 15 is formed in one step, the cost can be reduced as compared with the case where the film layers are formed on the diaphragm main body 11 and the edge 12 respectively.
[0040]
Furthermore, by setting the thickness of the synthetic resin film layer 15 to 25 to 45 μm, it is possible to obtain the free edge diaphragm 13 with little deformation and excellent waterproofness.
The present invention is not limited to the above embodiment.
[0041]
(1) In the above embodiment, the synthetic resin film layer 15 is formed over the entire back surface of the free edge diaphragm 13, but as shown in FIG. May be. Further, as shown in FIG. 3B, the synthetic resin film layer 15 may be formed over the entire surface of the free edge diaphragm 13 and the back surface.
[0042]
(2) Although the thickness of the synthetic resin film layer 15 of the above embodiment is 35 μm, the free edge diaphragm 13 having little deformation and excellent waterproofness is provided if the thickness is in the range of 25 to 45 μm. Can be obtained.
[0043]
(3) In the above embodiment, the synthetic resin film 20 was formed by heating and adsorbing the synthetic resin film 20 to the free edge diaphragm 13 using the apparatus shown in FIG. Using such an apparatus, the synthetic resin film layer 15 may be formed by thermocompression bonding.
[0044]
In FIG. 4, reference numeral 37 denotes a diaphragm receiving jig on which the free edge diaphragm 13 is placed. A plurality of exhaust pipes 36 are formed between the surface of the diaphragm receiving jig 37 on which the free edge diaphragm 13 is placed and the chamber 35 formed in the lower part. The chamber 35 is opened to the outside through an exhaust port 38.
[0045]
On the diaphragm receiving jig 37, a clamp 34 that holds the synthetic resin film 20 and can approach / separate from the diaphragm receiving jig 37 is provided. Reference numeral 40 denotes an air heating / pressure jig that is provided on the clamp 34 and is placed on the diaphragm receiving jig 37 with the synthetic resin film 20 interposed therebetween.
[0046]
The air heating / pressurizing jig 40 is provided with a heater 41 for heating the air inside, and further, pressurized air from a blower (not shown) is introduced into the inside through an intake hole 42. Yes.
[0047]
Insulating materials 43 and 44 are provided at the upper part of the diaphragm receiving jig 37 and the lower part of the air heating / pressurizing jig 40.
The operation of this apparatus will be described. A synthetic resin film 20 set in a clamp 34 is placed on a diaphragm receiving jig 37, and an air heating / pressurizing jig 40 is placed thereon.
[0048]
Then, the heater 41 is energized, the blower is driven, and pressurized air is introduced into the air heating / pressurizing jig 40. The introduced pressurized air is heated by the heater 41, softens the synthetic resin film 20, and thermocompresses the synthetic resin film 20 to the back surface of the free edge diaphragm 13.
[0049]
(5) In the above embodiment, the synthetic resin film layer 15 is made by blending 30% by weight of polyethylene with ethylene / ethyl acrylic coat / maleic anhydride terpolymer resin. Any ethylene-based copolymer resin containing dicarboxylic acid, dicarboxylic acid anhydride, and metal chloride thereof may be a material obtained by blending 1% to 40% by weight of polyethylene.
[0050]
【Example】
In order to confirm the effect of the present invention, the inventors of the present application formed various types of synthetic resin film layers over the entire back surface of the free edge diaphragm 13, and improved workability and initial characteristics at 80 ° C. and 110 ° C. The evaluation test of the waterproofness and deformation degree of was carried out. The result is shown in FIG.
[0051]
The initial characteristic means a state before a forced deterioration test such as a heat resistance test is performed, that is, a characteristic before being affected by the environment and time.
Moreover, the heat resistance of 80 ° C. is a heat resistance temperature applied for home use, and if it fails at this temperature, it cannot be used for home use.
[0052]
Furthermore, the heat resistance of 110 ° C. is a heat-resistant temperature applied for in-vehicle use, and if it fails at this temperature, it cannot be used for in-vehicle use.
In addition, the test method of waterproofness tested using the instrument as shown in FIG. In the figure, a free edge diaphragm 13 in which a synthetic resin film layer 15 is formed over the entire back surface is disposed between a lower cylinder 100 and an upper cylinder 110 sealed by packings 101 and 102, and the inside of the upper cylinder 110 The tap water was poured so that the water depth (H) was 20 mm, and the degree of water leaching after being allowed to stand for 24 hours was evaluated. The criterion was rejected when water oozes out even on the surface of the free edge diaphragm.
[0053]
In the deformation degree test, the degree of deformation after leaving the free edge diaphragm 13 in 50 ° C. and 90% RH for 3 hours and then in 20 ° C. and 65% RH for 1 hour was evaluated. As for the judgment criteria, it was accepted if the dimensions of each part were within tolerance, and was rejected if even one of them was off.
[0054]
In the heat resistance test, the free edge diaphragm 13 was left in a thermostat set at a predetermined temperature for 96 hours to evaluate the waterproofness and the degree of deformation. The determination criteria were the same as in the case of the degree of deformation.
[0055]
As can be seen from FIG. 5, the usable film thickness is 25 μm to 45 μm, and preferably 30 to 40 μm in consideration of in-vehicle use requiring high heat resistance.
In addition, those using the resin of the present invention (ethylene-based terpolymer + polyethylene) have a wide range of film thicknesses that pass the overall evaluation, and other things when considering various variations during mass production Compared to, it is possible to provide more stable products.
[0056]
Furthermore, since the film thickness can be reduced with the same function, the diaphragm mass can be reduced as a result, which can contribute to the improvement of the performance of the speaker.
[0057]
【The invention's effect】
As described above, according to the first aspect of the present invention, the thickness of the synthetic resin film layer is set to 25 to 45 μm, thereby obtaining a diaphragm for electroacoustic transducers with less deformation and excellent waterproofness. Can do.
[0058]
Synthetic resin film layer monocarboxylic acids, dicarboxylic acids, by a dicarboxylic acid anhydride and material for 1% to 40% parts by weight blend of polyethylene to ethylene copolymer resins containing these metal chlorides, good Water resistance, little deformation due to temperature change, high heat resistance, and good workability.
[0059]
According to invention of Claim 2 , the synthetic resin film layer of easy and uniform thickness can be formed by forming a synthetic resin film layer by either one of thermocompression bonding and heat adsorption. .
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a free edge diaphragm according to an embodiment of the present invention.
FIG. 2 is a configuration diagram of an apparatus used when the synthetic resin film layer shown in FIG. 1 is formed by a heat adsorption method.
FIG. 3 is a configuration diagram illustrating another embodiment.
4 is a configuration diagram of an apparatus used when the synthetic resin film layer shown in FIG. 1 is formed by a thermocompression bonding method.
FIG. 5 is a diagram showing the results of an evaluation test in an example.
FIG. 6 is a configuration diagram of an instrument used for a waterproof test in Examples.
FIG. 7 is a cross-sectional view of a free edge diaphragm.
FIG. 8 is a cross-sectional view of a main part of a conventional free edge diaphragm having waterproofness.
FIG. 9 is a cross-sectional view of a conventional free edge diaphragm that is waterproof.
[Explanation of symbols]
11 diaphragm main body 12 edge 13 free edge diaphragm (diaphragm for electroacoustic transducer)
15 Synthetic resin film layer

Claims (2)

A diaphragm for an electroacoustic transducer, comprising a diaphragm body and an outer peripheral edge of the diaphragm body, and comprising an edge made of a material different from that of the diaphragm body,
A synthetic resin film layer having a thickness of 25 to 45 μm is provided over the entire area of at least one surface of the diaphragm for the electroacoustic transducer ,
Further, the synthetic resin film layer is made of a material obtained by blending 1 % to 40 % by weight of polyethylene with an ethylene copolymer resin containing monocarboxylic acid, dicarboxylic acid, dicarboxylic acid anhydride and their metal chlorides. A diaphragm for an electroacoustic transducer. The diaphragm for an electroacoustic transducer according to claim 1, wherein the synthetic resin film layer is formed by one of thermocompression bonding and heat adsorption .

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