JP2012060414A - Speaker voice coil bobbin and speaker using the same and electronic equipment and device using the speaker - Google Patents

Abstract

[PROBLEMS] Generally, a paper voice coil bobbin has a demerit that it is easy to burn because it uses cellulose as a main raw material, and has a disadvantage that it is poor in flame retardancy. Means of adding high organic fibers and inorganic fibers, and means of impregnating with a flame retardant impregnating agent as a secondary processing have been devised, but this increases the weight of the vibration system and reduces the sound pressure. There is a problem that the manufacturing cost is increased due to a decrease, and the cost is increased.
A material composed of at least 30 wt% of metal hydroxide is made into a voice coil bobbin for a speaker in which a paper-made sheet is formed into a voice coil bobbin shape. Due to the mixed effect, flame retardancy can be imparted to the paper voice coil bobbin without increasing the weight and cost while improving the rigidity and realizing good sound quality.
[Selection] Figure 1

Description

  The present invention relates to a voice coil bobbin for a speaker used in various kinds of audio equipment and video equipment.

  In recent years, there is an increasing tendency to apply a large input to speakers used in various audio devices and video devices.

  For this reason, Joule heat is generated in the voice coil bobbin, and this heat accumulates to a high temperature. Therefore, a voice coil bobbin having excellent heat resistance is required.

  On the other hand, as a trend on the set side, thinning and high input resistance are progressing, and heat resistance is improved and flame resistance is reduced in order to reduce the risk of voice coil heat generation, ignition, or fire from other components. Is becoming an essential property.

  In response to this requirement, at present, a bobbin made of a kraft paper, a cylindrical bobbin made of aluminum or the like and a resin film is frequently used.

  Also, it is often used to provide bobbins with excellent heat resistance by impregnation and secondary treatment of paper, and polyimide resins with excellent heat resistance and workability.

  For example, Patent Documents 1, 2, and 3 are known as prior art document information relating to the invention of this application.

JP-A-6-70396 Japanese Patent Laid-Open No. 7-11099 JP-A-6-121388

  Paper voice coil bobbins are widely used because they are lightweight and inexpensive.

  However, there is a problem that the heat resistance is low and it is easy to burn, and the heat dissipation is poor, and this is the case when an abnormal current flows through the speaker or when the speaker periphery is abnormally heated. There has been a problem that there is a possibility that a fire may occur from the voice coil bobbin.

  Furthermore, the voice coil bobbin formed of paper material is inferior in moisture resistance and water resistance, and the paper material that has absorbed or absorbed moisture weakens the bond between the fibers and decreases its strength. In addition, there is a problem that it is not suitable for a speaker installed in a place where the environment is severe and water is directly applied or in a humid environment.

  Also, the paper voice coil bobbin has a drawback of low rigidity.

  The rigidity of pulp, which is the raw material of paper, is not sufficient. To eliminate this drawback, inorganic additives such as calcium carbonate and titanium dioxide are filled between the surface of the pulp fiber and between the fibers. Such inorganic fillers have high rigidity by themselves, but since most of them are adsorbed on the fiber surface, they fall off when pulp is beaten and have the disadvantage that they do not work effectively as paper rigidity. Yes.

  Further, the voice coil bobbin made of metal foil or polyimide film is expensive. In particular, in the case of metal foil, there is a problem to be solved that the vibration system becomes overbraking and the reproduction sound quality is not excellent.

  Furthermore, although the metal voice coil bobbin is excellent in heat resistance and moisture resistance, it has problems such as reducing the sound pressure level of the speaker in terms of heavy weight.

  In addition, the voice coil bobbin using a metal foil such as aluminum in order to solve the problems of the paper material has high heat resistance, but has a higher specific gravity than the paper material and resin, and good thermal conductivity. Therefore, heat generated from the voice coil is transmitted to the entire bobbin, and other parts such as the diaphragm, center cap, and damper attached to the voice coil, and the adhesive that fixes them together can be dissolved or ignited. Therefore, it is required to provide high heat resistance even for materials of these parts and the like.

  The polyimide resin is a resin having high heat resistance, but has a problem in that it may accumulate heat due to low thermal conductivity.

  Heat-resistant resin films such as polyimide and polyamide are used to solve the problems of this paper material, but they are expensive, inferior in adhesiveness, and have other problems such as melting at high temperatures. have.

  Accordingly, an object of the present invention is to provide a voice coil bobbin for a speaker that solves these problems and realizes flame retardancy, high sound quality, and low cost.

  In order to achieve the above-described object, the present invention provides a voice coil bobbin for a speaker by forming a paper sheet made of a material containing at least 30 wt% or more of a metal hydroxide into a voice coil bobbin shape. It is a thing.

  With this configuration, when the metal hydroxide is heated, it dehydrates and decomposes rapidly, exhibits a large endothermic reaction, and has the characteristic of imparting self-extinguishing properties to the material itself by being quenched by the crystal water generated at that time. By having it, it is possible to provide a voice coil bobbin for a speaker that imparts flame retardancy to a paper voice coil bobbin, and further achieves light weight, high sound quality, and low cost.

  As described above, according to the present invention, a voice coil bobbin for a speaker is formed into a voice coil bobbin shape by making a sheet made of a material including a metal hydroxide containing at least 30 wt% or more into a sheet coil shape. By using a coil bobbin, when the metal hydroxide is heated, it rapidly dehydrates and decomposes, exhibits a large endothermic reaction, and is extinguished by the crystal water generated at that time, thereby giving the material itself a self-extinguishing property By having the characteristics, flame retardancy can be imparted to the paper voice coil bobbin.

  Further, secondary processing such as impregnation is not required, and a voice coil bobbin for a speaker can be manufactured, so that new equipment investment is not required and manufacturing cost is not increased.

  Furthermore, the rigidity of the voice coil bobbin can be improved by mixing hard metal hydroxide compared to cellulose, which is the main raw material for paper voice coil bobbins, and it is possible to achieve higher sound quality by suppressing unnecessary distortion. Become.

The perspective view of the voice coil bobbin in one embodiment of this invention Sectional drawing of the speaker in one embodiment of this invention 1 is an external view of an electronic device according to an embodiment of the present invention. Sectional drawing of the vehicle in one embodiment of this invention

(Embodiment 1)
Hereinafter, a speaker voice coil bobbin according to an embodiment of the present invention will be described.

  FIG. 1 is a perspective view of a speaker voice coil bobbin 1 according to an embodiment of the present invention.

  As shown in FIG. 1, the voice coil bobbin 1 for a speaker is formed into a voice coil bobbin shape by making a sheet of a material composed of natural fiber 1A containing at least 30 wt% of metal hydroxide 1B. Thus, a voice coil bobbin for a speaker is obtained.

  Thus, desired flame retardance can be obtained by adding at least 30 wt% or more of metal hydroxide 1B.

  And in order to implement | achieve the outstanding flame retardance, it is desirable to add 50 wt% to 90 wt% of metal hydroxide.

  When the metal hydroxide to be added is less than 30 wt%, it is difficult to obtain desired flame retardancy, and the effect is small.

  On the other hand, when 90 wt% or more is added, the metal hydroxide is poorly dispersed when mixed, and the strength of the speaker voice coil bobbin is lowered.

  When a metal hydroxide is heated, it dehydrates and decomposes rapidly and exhibits a large endothermic reaction.

  The material itself has the property of imparting self-extinguishing properties by being extinguished by crystal water generated.

  In the case of improving the reliability such as strength, the metal hydroxide is preferably a metal hydroxide subjected to surface treatment such as stearic acid, a silane coupling agent, a titanate coupling agent, or a high white color.

  Representative examples of the metal hydroxide include aluminum hydroxide and magnesium hydroxide.

  As a metal hydroxide, a granular form is desirable.

  When the form of the metal hydroxide is granular, it can be efficiently dispersed and efficiently filled when paper is made into a sheet.

  The aluminum hydroxide to be added preferably has an average particle size of 100 μm or less.

  If the average particle diameter of aluminum hydroxide is 100 μm or less, it can have sufficient self-digestibility, and the rigidity of the diaphragm is improved, so that the sound quality can be improved.

  On the other hand, when the average particle size of aluminum hydroxide is 100 μm or more, poor dispersion occurs during paper making, and the self-extinguishing effect tends to be reduced.

Furthermore, it is desirable that the aluminum hydroxide to be added has a purity of 99% or more of Al (OH) ₃ which is a main component.

When the purity of Al (OH) ₃ which is a main component of aluminum hydroxide is 99% or less, the effect is lowered and sufficient self-digestibility cannot be obtained.

  Next, it is desirable that the magnesium hydroxide to be added has an average particle size of 100 μm or less.

  If the average particle diameter of magnesium hydroxide is 100 μm or less, sufficient self-digestibility can be obtained, and the rigidity of the diaphragm is further improved, so that sound quality can be improved.

  On the other hand, when the average particle size of magnesium hydroxide is 100 μm or more, poor dispersion occurs during paper making, and the self-extinguishing effect tends to be reduced.

  Further, the magnesium hydroxide to be added preferably has a purity of 60% or more of the main constituent MgO.

  When the purity of MgO, which is the main component of magnesium hydroxide, is 60% or less, the effect is lowered and sufficient self-digestibility cannot be obtained.

  Next, as the papermaking material, non-wood can be used instead of wood pulp. In this case, various fibers such as bamboo, kenaf, jute, bagasse, hemp and the like can be used.

  And it becomes possible to suppress logging of timber by increasing the ratio, and a diaphragm with a small load to the environment can be provided.

  Among the many non-wood fibers, bamboo fibers are fast growing and rarely cause environmental problems. They can be supplied continuously, and can be discarded by incineration without being buried like inorganic fibers such as glass fibers. Because it is environmentally friendly.

  When bamboo fiber is used as a papermaking material, it is desirable to use bamboo fiber obtained from bamboo that is one year old or older.

  In general, bamboo grows about 50 days after birth, and then stabilizes as a material. After almost a year or more, a stable material can be obtained, so that desired characteristics can be obtained as an acoustic member. .

  However, no matter how fast the bamboo grows, if it continues to be harvested within the first year of life, the bamboo forest will not grow stably, and there is a concern that the bamboo ecosystem will be disturbed.

  Next, the amount of bamboo fiber added is desirably 70 wt% or less.

  If the amount of bamboo fiber added is 70 wt% or less, a diaphragm having high rigidity and high internal loss can be obtained, and therefore a diaphragm having a very glossy sound quality can be obtained.

  On the other hand, when the addition amount of bamboo fiber is 70 wt% or more, the compounding amount of the metal hydroxide is relatively reduced and the desired flame retardancy cannot be obtained.

  If the fiber is beaten to a level of 200 ml or more and 700 ml or less according to the Canadian standard freeness, the fiber has an appropriate rigidity and hardly causes poor dispersion during paper making.

  Here, if it is 200 ml or less, the drainage speed is lowered during paper making, and the productivity is remarkably lowered.

  On the other hand, when the amount is 700 ml or more, the entanglement between the fibers becomes low, so that the expected effect is hardly obtained.

  As a method for beating the bamboo fiber, there are methods such as a disc refiner and a beater.

  If the fiber length of the bamboo fiber is a natural fiber of 0.8 mm or more and 3 mm or less, the reinforcing effect as the main point can be sufficiently exerted, and the papermaking unevenness when the paper is mixed can be suppressed.

  Here, if the fiber length of the bamboo fiber is 0.8 mm or less, the entanglement between the fibers is insufficient, and the strength of the preformed paper is insufficient, and sufficient characteristics cannot be obtained.

  Further, when the metal hydroxide is mixed, if the fiber length is short, the ratio of fixing to the fiber becomes low, and there is a concern that the flame retardancy may be lowered.

  On the other hand, if the fiber length of the bamboo fiber is 3 mm or more, a dispersion failure is formed at the time of blending, which tends to cause a decrease in dispersibility and a defective appearance of the molded product.

If the density of the voice coil bobbin 1 is 0.30 g / cm ³ or more and 0.90 g / cm ³ or less, it can be formed without impairing the softness and lightness inherent in the paper. .

Here, in the case of 0.30 g / cm ³ or less, the strength is remarkably reduced, so that abnormal noise due to insufficient strength such as surface noise in a high frequency region is likely to occur.

On the other hand, when the density is 0.90 g / cm ³ or more, the specific gravity is equivalent to that of a resin diaphragm, and it cannot boast of superiority in terms of lightness, which is a feature of a paper voice coil bobbin, and deteriorates characteristics such as a decrease in sound pressure. It is easy to invite.

  If the content of lignin in the bamboo fiber is 25 wt% or less, rich sound quality can be realized due to the high internal loss of lignin.

  On the other hand, when the content of lignin is 25 wt% or more, since the bamboo fiber surface contains excessive lignin, adhesion between the bamboo fibers is hindered and the strength is insufficient when molded as a diaphragm. It becomes difficult.

  Furthermore, as a means for effectively improving the sound quality, it is desirable to add bamboo fiber refined to a microfibril state as an auxiliary material.

  The addition ratio is desirably 5 wt% or more and 20 wt% or less of bamboo fiber reduced to a microfibril state.

  If it is between 5 wt% and 20 wt%, an effective reinforcing effect can be obtained as a binder for connecting fibers together.

  If the addition amount of the bamboo fiber refined to the microfibril state is 5 wt% or less, the addition amount is too small to obtain a sufficient reinforcing effect.

  On the other hand, if it is 20 wt% or more, it will cause a dispersion | distribution defect at the time of papermaking, and will tend to cause the external appearance defect of a diaphragm.

  In general, fibers refined to a microfibril state have low drainage, so that the time until dewatering in the paper making process becomes very long, and the production cost is remarkably increased.

  Therefore, the appropriate addition amount is preferably 5 wt% or more and 20 wt% or less.

  Moreover, if the fiber length of the bamboo fiber refined to the microfibril state is refined to 0.8 mm or less, it is sufficiently refined, and the entanglement between the fibers is promoted, and a desired reinforcing effect can be obtained. .

  On the other hand, if the fiber length is 0.8 mm or more, the bamboo fibers are not sufficiently beaten, so that the entanglement between the fibers is insufficient and the reinforcing effect is poor.

  Furthermore, it is desirable that the beating degree of the bamboo fiber reduced to the microfibril state is 200 ml or less.

  If the beating degree is 200 ml or less, an overwhelming reinforcing effect can be obtained as compared with a normal bamboo fiber, and even if the addition amount is small, an excellent cost-effectiveness can be obtained.

  If it is 200 ml or more, it is a characteristic of a comparable level compared with a general bamboo fiber, and it is difficult to obtain the reinforcement effect as a microfibril fiber.

  Furthermore, it is possible to improve the flame retardancy and adjust the sound quality by blending a reinforcing material as necessary.

  As the reinforcing material, inorganic fibers and metal fibers can be added as reinforcing fibers and a sound quality adjusting material.

  Examples of the inorganic fiber include glass fiber, carbon fiber, and ceramic fiber.

  Examples of metal fibers include stainless steel fibers.

  The addition amount of the glass fiber is desirably 5 wt% to 40 wt%. If the addition is performed with this addition amount, the flame retardancy of the paper voice coil bobbin can be further improved.

  Moreover, since glass fiber is hard, it is possible to increase the rigidity of the paper voice coil bobbin by mixing paper.

  In the case of an addition amount of 5 wt% or less, it is difficult to obtain effects such as flame retardancy and high rigidity.

  In the case of 40 wt% or more, various disadvantages such as uneven papermaking, poor appearance, and increased specific gravity occur.

  The addition amount of the carbon fiber is desirably 5 wt% to 40 wt%, and if it is mixed with this addition amount, the flame retardancy of the paper voice coil bobbin can be further improved.

  In addition, since the carbon fiber is hard, it is possible to increase the rigidity of the paper voice coil bobbin by mixing the carbon fibers.

  In the case of an addition amount of 5 wt% or less, it is difficult to obtain effects such as flame retardancy and high rigidity.

  In the case of 40 wt% or more, various disadvantages such as uneven papermaking, poor appearance, and increased specific gravity occur.

  The addition amount of the ceramic fiber is desirably 5 wt% to 40 wt%, and if it is mixed with this addition amount, the flame retardancy of the paper voice coil bobbin can be further improved.

  In addition, since the ceramic fiber is hard, the paper voice coil bobbin can be made highly rigid by mixing.

  In the case of an addition amount of 5 wt% or less, it is difficult to obtain effects such as flame retardancy and high rigidity.

  In the case of 40 wt% or more, various disadvantages such as uneven papermaking, poor appearance, and increased specific gravity occur.

  The addition amount of the stainless steel fiber is desirably 5 wt% to 40 wt%, and if it is mixed with this addition amount, the flame retardancy of the paper voice coil bobbin can be further improved.

  In addition, since the stainless steel fiber is hard, it is possible to increase the rigidity of the paper voice coil bobbin by mixing paper.

  In the case of an addition amount of 5 wt% or less, it is difficult to obtain effects such as flame retardancy and high rigidity.

  In the case of 40 wt% or more, various disadvantages such as uneven papermaking, poor appearance, and increased specific gravity occur.

  Further, it is possible to improve the flame retardancy and adjust the sound quality by blending a filler.

  The filler is preferably added with calcium carbonate, talc, mica, carbonized natural fiber.

  The addition amount of calcium carbonate is desirably 5 wt% to 20 wt%. If mixed with this addition amount, the flame retardancy of the paper voice coil bobbin can be further improved.

  In addition, since calcium carbonate is hard, it is possible to increase the rigidity of the paper voice coil bobbin by mixing paper.

  In the case of an addition amount of 5 wt% or less, it is difficult to obtain effects such as flame retardancy and high rigidity.

  If it is 20 wt% or more, various disadvantages such as uneven papermaking, poor appearance, and increased specific gravity occur.

  The amount of talc added is preferably 5 wt% to 20 wt%. If the amount of talc is mixed, the flame retardancy of the paper voice coil bobbin can be further improved.

  In addition, since talc is hard, it is possible to increase the rigidity of the paper voice coil bobbin by mixing paper.

  In the case of an addition amount of 5 wt% or less, it is difficult to obtain effects such as flame retardancy and high rigidity.

  If it is 20 wt% or more, various disadvantages such as uneven papermaking, poor appearance, and increased specific gravity occur.

  The addition amount of mica is desirably 5 wt% to 20 wt%. If the addition is performed with this addition amount, the flame retardancy of the paper voice coil bobbin can be further improved.

  In addition, since mica is hard, it is possible to increase the rigidity of the paper voice coil bobbin by mixing paper.

  In the case of an addition amount of 5 wt% or less, it is difficult to obtain effects such as flame retardancy and high rigidity.

  If it is 20 wt% or more, various disadvantages such as uneven papermaking, poor appearance, and increased specific gravity occur.

  The addition amount of the carbonized natural fiber is desirably 5 wt% to 20 wt%, and if it is mixed with this addition amount, the flame retardancy of the paper voice coil bobbin can be further improved.

  In addition, since the carbonized natural fiber is hard, it is possible to increase the rigidity of the paper voice coil bobbin by blending.

  In the case of an addition amount of 5 wt% or less, it is difficult to obtain effects such as flame retardancy and high rigidity.

  If it is 20 wt% or more, various disadvantages such as uneven papermaking, poor appearance, and increased specific gravity occur.

  In addition, since carbonized natural fiber has innumerable pores on its surface, it can be expected to reduce specific gravity and improve internal loss.

  It is also possible to improve flame retardancy and sound quality by combining known techniques such as pigments, waterproofing agents, and impregnation treatments.

(Embodiment 2)
A speaker using the speaker voice coil bobbin 1 described in the first embodiment will be described below.

  FIG. 2 shows a cross-sectional view of the speaker of the present embodiment.

  As shown in FIG. 2, a magnetized magnet 2 is sandwiched between an upper plate 3 and a yoke 4 to form an internal magnet type magnetic circuit 5.

  A frame 7 is coupled to the yoke 4 of the magnetic circuit 5.

  The outer periphery of the speaker diaphragm 8 is bonded to the peripheral portion of the frame 7 via an edge 9.

  Then, one end of the voice coil is coupled to the central portion of the speaker diaphragm 8 and the opposite end is coupled so as to fit into the magnetic gap 6 of the magnetic circuit 5.

  The speaker voice coil bobbin 1 is formed by forming a sheet of paper material made of a metal hydroxide containing at least 30 wt% or more into a voice coil bobbin shape.

  In the above, the speaker having the inner magnet type magnetic circuit has been described.

  With the above configuration, a speaker capable of realizing flame retardancy, high sound quality, and cost reduction can be realized.

(Embodiment 3)
Hereinafter, the mini component system 14 using the speaker described in the second embodiment will be described.

  FIG. 3 is an external view of an audio mini-component system 14 that is an electronic device equipped with a speaker.

  As shown in FIG. 3, the mini component system 14 of the present embodiment includes an enclosure 11 in which a speaker 10 is incorporated, an amplifier 12 that is an amplifying means for an electric signal input to the speaker 10, and an input to the amplifier 12. The player 13 outputs a source to be played.

  The bobbin used in the voice coil of the speaker 10 is formed by forming a sheet of a material made of a metal hydroxide containing at least 30 wt% into a voice coil bobbin shape. is there.

  With this configuration, the mini-component system 14 can realize flame retardance, high sound quality, and cost reduction that could not be realized in the past.

(Embodiment 4)
Hereinafter, an apparatus in which the speaker 10 described in the second embodiment is mounted on a moving unit will be described.

  FIG. 4 is a sectional view of the vehicle 15 on which the speaker 10 is mounted.

  As shown in FIG. 4, the vehicle 15 of the present embodiment is one in which the speaker 10 is incorporated in a rear tray or a front panel and used as a part of car navigation or car audio.

  The bobbin used in the voice coil of the speaker 10 is formed by forming a sheet of a material made of a metal hydroxide containing at least 30 wt% into a voice coil bobbin shape. is there.

  By setting it as this structure, the vehicle 15 can implement | achieve the flame retardance and high sound quality which were not realizable conventionally, and can contribute to the reduction of the safety | security, comfort, and cost.

  The voice coil bobbin for a speaker, speaker, electronic device and apparatus according to the present invention are an electronic device such as an audiovisual device or an information communication device that requires both flame retardancy, high sound quality, and cost reduction, and an automobile, etc. Applicable to any device.

DESCRIPTION OF SYMBOLS 1 Speaker voice coil bobbin 1A Natural fiber 1B Metal hydroxide 2 Magnet 3 Upper plate 4 Yoke 5 Magnetic circuit 6 Magnetic gap 7 Frame 8 Speaker diaphragm 9 Edge 10 Speaker 11 Enclosure 12 Amplifier 13 Player 14 Mini component system 15 Vehicle

Claims (16)

A voice coil bobbin for a speaker, wherein the voice coil bobbin for a speaker is made of a material made of a metal hydroxide containing at least 30 wt% or more and made into a sheet shape by making paper into a voice coil bobbin shape. Coil bobbin. The voice coil bobbin for a speaker according to claim 1, further comprising non-wood. The voice coil bobbin for a speaker according to claim 2, wherein the non-wood is bamboo fiber. 4. The voice coil bobbin for a speaker according to claim 3, comprising bamboo fibers obtained from bamboo that is one year old or older. The voice coil bobbin for a speaker according to claim 3, wherein the bamboo fiber is 70 wt% or less. 4. The voice coil bobbin for a speaker according to claim 3, wherein the beat coil bobbin has a beating degree of 200 ml or more and 700 ml or less at a Canadian freeness. 4. The voice coil bobbin for a speaker according to claim 3, wherein the voice coil bobbin is a bamboo fiber having a fiber length of 0.8 mm or more and 3 mm or less. The voice coil bobbin for a speaker according to claim 1, wherein the density is 0.30 g / cm ³ or more and 0.90 g / cm ³ or less. The voice coil bobbin for a speaker according to claim 3, wherein the lignin content in the bamboo fiber is 25 wt% or less. 4. The voice coil bobbin for a speaker according to claim 3, wherein the bamboo fiber is reduced to a microfibril state and the content is set to 5 wt% or more and 20 wt% or less. The voice coil bobbin for a speaker according to claim 10, wherein the bamboo fiber reduced to a microfibril state has a fiber length of 0.8 mm or less. The voice coil bobbin for a speaker according to claim 10, wherein the bamboo fiber reduced to a microfibril state has a beating degree of 200 ml or less. The speaker voice coil bobbin according to claim 1, further comprising a reinforcing material. The speaker diaphragm, the outer periphery of the speaker diaphragm are coupled, the frame coupled to the magnetic circuit, and the speaker diaphragm are coupled to a magnetic gap formed by the magnetic circuit. A voice coil bobbin for a speaker having a voice coil bobbin formed by making a sheet of a material made of a metal hydroxide containing at least 30 wt% of a metal hydroxide and forming it into a sheet shape. Speaker. An electronic device including at least a speaker and an amplification unit for an input signal to the speaker, wherein the speaker is coupled to a speaker diaphragm and an outer peripheral portion of the speaker diaphragm and to a magnetic circuit. A voice coil coupled to the speaker diaphragm and movably disposed in a magnetic gap formed by the magnetic circuit, and the voice coil includes at least 30 wt% or more of metal hydroxide. An electronic device provided with a voice coil bobbin for a speaker, which is formed by making a sheet of a material composed of the above material into a sheet shape. A speaker and a device in which the speaker is mounted on a moving means, the speaker having a speaker diaphragm, a frame coupled with an outer peripheral portion of the speaker diaphragm, and a magnetic circuit; At least a voice coil coupled to a speaker diaphragm and movably disposed in a magnetic gap formed by the magnetic circuit. The voice coil is made of a material including at least 30 wt% or more of metal hydroxide. An apparatus equipped with a voice coil bobbin for a speaker, which is formed into a voice coil bobbin shape by making a paper sheet.

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