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JP2000134692

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DESCRIPTION JP2000134692
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
diaphragm and a voice coil bobbin of a speaker used in various acoustic devices.
[0002]
2. Description of the Related Art In general, a speaker is a drive system component such as a
voice coil, a magnet, a yoke, a yoke plate, a center pole, a vibration system component such as a
diaphragm, a cap, an edge or a damper; And so on.
[0003]
The voice coil is a movable coil, and is disposed orthogonal to the magnetic flux in a uniform
magnetic field formed by the magnet.
When a voice current flows in the voice coil, an electromagnetic force is generated in the vertical
direction of the voice coil, and the voice coil vibrates according to the voice current. The
vibration is transmitted to the diaphragm integrated with the voice coil, the movement of the
diaphragm becomes a compressional wave of air, and the sound wave is emitted by the operation
principle of the speaker.
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[0004]
The above-mentioned voice coil is generally produced by winding a wire on a voice coil bobbin
(hereinafter referred to as a bobbin) formed by cutting paper into a strip and forming both ends
into a tubular shape. Further, instead of paper, for example, a thin metal foil such as aluminum
foil, and a heat resistant resin film such as polyamide or polyimide are similarly rounded to form
a cylindrical shape, and is widely used as a bobbin.
[0005]
Moreover, as a material of the above-mentioned diaphragm, generally, a fiber material
represented by paper or the like, a metal material, a plastic material or the like is used.
[0006]
In recent years, in order to cope with high-quality digital music sources, a speaker having better
acoustic characteristics such as output sound pressure, distortion rate, flatness of frequency
characteristics, and the like than in the past is desired. ing.
Of the various components that make up the speaker, it is the performance of the diaphragm that
in particular influences the acoustic characteristics. Although it is ideal for the diaphragm to
perform piston movement over the entire range of the frequency used, in reality, due to
deformation and split vibration of the diaphragm, sound pressure-frequency characteristics,
distortion rate, and phase characteristics are It degrades and degrades the acoustic performance.
[0007]
As a problem of the conventional diaphragm, specifically, for example, a diaphragm made of
100% natural pulp is weak in rigidity, and a diaphragm made of metal material is excellent in
rigidity but high in material cost and deep The diaphragm can not be drawn, has a high weight
and a low loss, and can be further characterized in that the diaphragm made of a polymer
material such as plastic is inferior in heat resistance and adhesion.
[0008]
Moreover, since the above-mentioned paper diaphragm and plastic diaphragm have a generally
low specific elastic modulus E / ρ (E: elastic modulus, :: density) of the diaphragm material, the
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high region resonance frequency is low, and the speaker It also has the disadvantage of not being
able to play up to high frequencies.
[0009]
That is, all of the conventional diaphragm materials described above are generally low in cost,
light in weight, small in specific gravity, and excellent in various physical properties such as heat
resistance, rigidity, and elastic modulus, which are also characteristic of the diaphragm materials.
It does not satisfy everything.
[0010]
On the other hand, the conventional voice coil has the following problems.
[0011]
For example, if the bobbin constituting the voice coil is a paper bobbin, it generally vibrates
according to the input audio current because it is light in weight and small in specific gravity, but
has poor heat resistance, so the voice during speaker operation The heat generated by the coil
shrinks and an adhesive peel occurs between the lead wire wound on the paper bobbin and the
bobbin.
Generally, the input resistance of the speaker is determined by the heat resistance of the voice
coil.
Therefore, in a voice coil using a paper bobbin, it is difficult to obtain a high power speaker.
Furthermore, the paper bobbin can not efficiently transmit the vibration of the voice coil to the
diaphragm because the elastic modulus of the material is generally low.
In addition, although metal foil bobbins are generally excellent in elastic modulus, since the
bobbins are conductive, eddy currents are generated inside the bobbins to suppress vibration,
leading to deterioration of reproduced sound quality, and Cost is high. Furthermore, although
bobbins made of polyamide or polyimide are generally light in weight and small in specific
gravity, they are deformed by heat because they have a large coefficient of thermal expansion
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and anisotropy in expansion. That is, all the above-mentioned conventional bobbin materials
generally satisfy all the characteristics found in the bobbin materials, such as low cost, light
weight, small specific gravity, and excellent in various physical properties such as heat resistance
and elastic modulus. is not.
[0012]
The present invention has been made to solve the above-mentioned problems, and its object is
generally to lower the cost, and also to achieve the rigidity and elasticity of paper inherently
having material properties of light weight and small specific gravity. An object of the present
invention is to provide a diaphragm and a bobbin as speaker parts excellent in various acoustic
characteristics at low cost by improving various physical properties such as rate and heat
resistance and using this paper as a material.
[0013]
[Means for Solving the Problems] In order to solve the above-mentioned problems, the
diaphragm according to claim 1 of the present invention comprises a paper formed by absorbing
and drying a zinc chloride solution at least in part. It is characterized by
[0014]
According to the above configuration, the paper obtained by absorbing and drying the zinc
chloride solution increases the number of hydrogen bonds acting between fibers in the paper and
in the fibers, and various physical properties such as rigidity, elastic modulus and heat resistance
Improve.
Therefore, if the above-mentioned paper is used as a diaphragm material, in addition to the
material properties which the paper originally has, which is generally low in cost, light in weight
and small in specific gravity, the diaphragm has large elastic modulus and bending rigidity. Can
be provided.
That is, the diaphragm in which the deformation of the diaphragm and the occurrence of split
resonance are suppressed can be provided at low cost.
[0015]
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Therefore, by using the diaphragm according to the present invention, it is possible to
inexpensively provide a speaker excellent in various acoustic characteristics such as an excellent
sound pressure-frequency characteristic and a small distortion factor and a high high-resonance
frequency.
[0016]
In order to solve the above-mentioned problems, the voice coil bobbin according to claim 2 of the
present invention is characterized in that it comprises paper made by absorbing and drying a
zinc chloride solution at least in part.
[0017]
According to the above configuration, the paper obtained by absorbing and drying the zinc
chloride solution increases the number of hydrogen bonds acting between fibers in the paper and
in the fibers, and various physical properties such as rigidity, elastic modulus and heat resistance
Improve.
Therefore, a highly elastic bobbin can be provided inexpensively without deformation due to heat
or the like.
[0018]
In addition, the bobbin has material properties such as lightness, small specific gravity, and the
like which paper originally has, so that the weight of the voice coil can be reduced.
Therefore, the voice coil vibrates faithfully according to the input audio current, and the vibration
is transmitted to the diaphragm to obtain effects such as a high maximum reproduction
frequency and an expanded reproduction range. Be
[0019]
Therefore, by using the bobbin according to the present invention, it is possible to inexpensively
provide a speaker excellent in various acoustic characteristics such as an excellent sound
pressure-frequency characteristic and a small distortion factor and a high high-resonance
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frequency.
[0020]
DETAILED DESCRIPTION OF THE INVENTION The paper, the zinc chloride solution, the zinc
chloride solution treatment, and the drying process according to the present invention will first
be described in detail.
[0021]
The paper in the present invention is mainly composed of entanglement of fibers in which fibers
are bonded to each other.
In addition, the production process of the paper is also not particularly limited, and addition of,
for example, sizing agents typified by rosin, various hydrocarbons, natural waxes, starch, etc .;
Agents may be added or processed.
The paper is more preferably one having high strength, and examples thereof include paper
made of sulfated pulp (kraft pulp) such as kraft paper.
[0022]
The zinc chloride solution in the present invention is not particularly limited as long as it is a
solution containing at least zinc chloride dissolved, and specifically, for example, zinc chloride,
water, ethanol, acetone, ether or the like, or these What was melt | dissolved in the mixed solvent
of a solvent can be mentioned. In addition, for the purpose of rapidly drying the paper after the
zinc chloride solution treatment described below, the solvent in which zinc chloride is dissolved
is preferably a volatile solvent, and the above-mentioned paper may also be dried after drying.
For the purpose of preventing the remaining of the physical properties of the paper from
remaining, it is preferable to use a solvent which does not react or adsorb with the fibers in the
paper. Further, the zinc chloride solution may contain the above-mentioned sizing agent,
additives and the like in a solvent, and for example, zinc chloride is added to an aqueous solution
in which fibers are dispersed in the middle of a paper making process. It shall also contain a
solution.
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[0023]
The concentration of the zinc chloride solution is not particularly limited, but is preferably more
than 0 and 30% by weight or less, in order to obtain a high elastic modulus of the paper after the
zinc chloride solution treatment. More preferably, it is at least 20% by weight. For example, when
zinc chloride is dissolved in water, up to 420 g of zinc chloride can be dissolved in 100 g of
water at room temperature, but highly concentrated zinc chloride solution has the property of
dissolving cellulose regardless of the type of solvent. There are also reports of the risk of skin
problems. Specifically, it is known that when the concentration is 30% by weight or more, various
physical properties are degraded.
[0024]
There is no particular limitation on the method of absorbing the zinc chloride solution in the
paper, that is, the method of performing the zinc chloride solution treatment, and any method
may be particularly limited as long as at least a part of the paper absorbs the zinc chloride
solution. is not. As a method of performing a zinc chloride solution treatment, for example,
specifically, immersing the paper in a zinc chloride solution, attaching a zinc chloride solution to
the paper by brush coating or spray coating, etc. Can.
[0025]
The treatment time of the zinc chloride solution treatment is not particularly limited and may be
appropriately set according to the concentration of the zinc chloride solution, but if the
concentration of the zinc chloride solution is 10% by weight or more, the treatment is By setting
the time to 30 minutes or more, the elastic modulus of the paper can be made sufficiently high.
However, if the zinc chloride solution treatment is performed for too long, the cellulose contained
in the paper may be decomposed regardless of the concentration of the zinc chloride solution.
[0026]
Further, the time of performing the zinc chloride treatment is not particularly limited, and can be
performed, for example, after a stock preparation process, a beating process, a paper making
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process, after paper making, or after forming paper as a speaker component. Further, the number
of processes performed in each of the above steps is not particularly limited, as long as the
process is performed at least once when used as a speaker component. Furthermore, it is also
possible to partially process the paper, if necessary.
[0027]
The paper absorbed with the zinc chloride solution is used as a speaker component after being
dried. In the present invention, the term "drying" refers to drying and removing the solvent
dissolving zinc chloride from the paper after the zinc chloride solution treatment, and also
includes drying by leaving the paper under normal temperature and normal pressure. The drying
method of the solvent is not particularly limited, and can be determined according to the type of
the solvent and the like. Examples of the method for drying the solvent include, for example, heat
drying, drying under reduced pressure, drying with a desiccant, and a combination of these
methods.
[0028]
Moreover, the time to dry is not specifically limited, It can carry out after the said zinc chloride
solution process is performed. The drying is not required to be completely performed each time
the zinc chloride solution treatment is performed, and may be completely dried at the time of
being used as a speaker part.
[0029]
DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] The following description
will explain an embodiment of the present invention in reference to FIGS. The present invention
is not limited by this.
[0030]
Specifically, the diaphragm according to the present embodiment is a speaker diaphragm used
for a cone type speaker. The diaphragm is generally constituted by a cone portion 1 and an edge
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portion 2 as shown in FIG. 1 and is integrated with a voice coil. Then, the vibration of the voice
coil to which the audio current is input is transmitted by being transmitted, the movement of the
diaphragm becomes the compressional wave of air, and the sound wave is emitted.
[0031]
The diaphragm is manufactured, for example, by the method described below.
[0032]
First, using a kraft pulp as a raw material, a cone-like portion 1 having a thickness of 0.2 mm is
prepared by a conventional papermaking method, and immersed in a 20% by weight aqueous
zinc chloride solution (zinc chloride solution) for 20 minutes at room temperature. And increased
rigidity.
According to the conditions of the zinc chloride solution processing, as shown in FIG. 2, it is
possible to obtain an almost maximum elastic modulus in a short time.
[0033]
Subsequently, the cone portion 1 was pulled up from a zinc chloride aqueous solution and dried,
and then a rubber edge portion 2 separately formed on the outer peripheral portion of the cone
portion 1 was adhered to obtain a diaphragm having a diameter of 10 cm.
[0034]
In the present embodiment, the edge portion 2 is made of rubber and is formed in a substantially
semicircular roll shape, but the shape and material of the edge portion 2 are not particularly
limited.
Further, the diameter of the diaphragm is not particularly limited.
[0035]
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The physical properties [elastic modulus, internal loss (loss), and density] of the diaphragm
according to the present embodiment are as follows: vibration of 0.2 mm thick conventional
paper not treated with zinc chloride solution with 100% natural pulp As a result of comparison
with the plate, the modulus of elasticity is greatly improved from 0.80 × 10 10 dyn / cm 2 to
1.84 × 10 10 dyn / cm 2. Also, the density increased slightly from 0.55 g / cm 3 to 0.62 g / cm
3, while the internal loss (tan δ) decreased slightly from 0.50 to 0.45. Further, the specific
elastic modulus E /: (E: elastic modulus, ρ: density) greatly improved from 1.45 × 10 10 cm 2 /
s 2 to 2.97 × 10 10 cm 2 / s 2. The internal loss is a constant specific to each substance, which
indicates the magnitude of relaxation of external stress inside the substance (thermally), and was
measured from the natural attenuation of the cantilever single pluse vibration.
[0036]
As is clear from the above results, by performing the immersion treatment in a zinc chloride
aqueous solution, it is possible to obtain a compact paper diaphragm part having a remarkably
improved elastic modulus. Generally, the elastic modulus of paper and the internal loss are in a
contradictory relationship, and it is said that it is very difficult to improve both the elastic
modulus and the internal loss. Even in the present embodiment, the internal loss is slightly
reduced along with the improvement of the elastic modulus, but the degree of the reduction can
be evaluated as being smaller than the improvement of the elastic modulus, and is desired as a
speaker component It does not deviate from the condition of “low density, high rigidity, and
moderate internal loss”. In the present embodiment, the reason why the reduction in the
internal loss is suppressed is considered to be that the internal loss of the pulp that forms the
paper is maintained.
[0037]
Next, a cone-type speaker is manufactured using the diaphragm according to the present
embodiment, and the sound with the cone-type speaker using the conventional paper diaphragm
made of 100% natural pulp and not treated with the zinc chloride solution The pressurefrequency characteristics were compared. Between the two cone-shaped speakers used in the
comparison, the same speaker parts other than the diaphragm are used, and the parts are
assembled by the same assembling process.
[0038]
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The result of the comparison of the above-mentioned sound pressure-frequency characteristics is
shown in FIG. In FIG. 3, the sound pressure-frequency characteristic of the cone type speaker
using the diaphragm according to the present embodiment is represented by a solid line B, and
the sound pressure-frequency of the cone type speaker using the conventional paper diaphragm
The characteristic is represented by a solid line A. As is clear from FIG. 3, in the cone-type
speaker using the diaphragm according to the present embodiment, the drop in sound pressure
is effectively suppressed in the high frequency region, and in a wide frequency region as
compared with the conventional one. It is possible to realize a flat sound pressure.
[0039]
The diaphragm according to the present embodiment is the conventional paper-made vibration
that is not subjected to the zinc chloride solution treatment because the number of hydrogen
bonds between the fibers forming the paper and in the fibers is increased by the zinc chloride
solution treatment. The modulus of elasticity and the bending stiffness are very high compared to
the plate. Therefore, deformation of the diaphragm and occurrence of split resonance are
suppressed, good acoustic characteristics can be obtained, distortion factor can be reduced by 20
dB as compared with the conventional paper diaphragm, and high frequency resonance
frequency is from 18 KHz It can be raised to 25 KHz.
[0040]
The diaphragm according to the present invention does not have to be entirely made of paper, as
long as at least a part of it is made of paper. For example, it may be a diaphragm made of paper
as a base material and a binder, reinforcing material, damping material, etc. made of materials
other than paper as appropriate, and further, a diaphragm made of a combination of materials
containing paper as one component. May be. Further, the diaphragm is not limited to one for a
cone type speaker, and may be a dome type or horn type speaker diaphragm.
[0041]
Second Embodiment The following description will explain another embodiment of the present
invention, while referring to FIGS. The present invention is not limited by this.
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[0042]
The bobbin according to the present embodiment is, as shown in FIG. 4, wound around the
conducting wire 4 along the outer periphery of the bobbin 3 to form a voice coil, which is
integrally provided with the diaphragm 5 and used. The voice coil is vibratably attached
according to the audio current input to the conductor 4.
[0043]
The bobbin 3 is manufactured, for example, by the method described below.
[0044]
First, a 50 μm-thick paper manufactured by a conventional paper making method using kraft
pulp as a raw material was made to have high rigidity in the same manner as in the first
embodiment.
According to the conditions of this zinc chloride solution treatment (immersed in a 20% by
weight aqueous solution of zinc chloride for 20 minutes), as shown in FIG. 5, it is possible to
obtain an almost maximum elastic modulus in a short time.
Subsequently, the paper was pulled from a zinc chloride aqueous solution and dried, and then cut
into strips, and both ends were put together and rolled into a cylinder to form a bobbin 3
according to the present embodiment.
[0045]
As a result of comparing the physical properties of the bobbin 3 according to the present
embodiment with a conventional paper bobbin made of a 50 μm thick paper not treated with a
zinc chloride solution with 100% natural pulp, the elastic modulus is The maximum usable
temperature (i.e., the temperature at which the paper bobbin carbonizes) greatly improved from
200 DEG C. to 240 DEG C. from 11.4.times.10@10 dyn / cm @ 2 to 17.1.times.10@10 dyn / cm
@ 2, respectively.
[0046]
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Next, the conducting wire 4 was wound along the outer periphery of the bobbin 3 to form a voice
coil, and a cone-shaped speaker with a diameter of 10 cm was produced.
[0047]
And the sound pressure-frequency characteristic was compared with the cone type speaker
carrying the voice coil using the conventional paper bobbin which the zinc chloride solution
process is not performed by 100% of natural pulp.
Among the two cone-shaped speakers used in the comparison, the same speaker parts except for
the bobbin are used, and the parts are assembled by the same assembling process.
[0048]
The result of the comparison of the above-mentioned sound pressure-frequency characteristics is
shown in FIG.
In FIG. 6, the sound pressure-frequency characteristic of a cone type speaker equipped with a
voice coil using a bobbin 3 according to the present embodiment is indicated by a solid line B,
and a cone equipped with a voice coil using a conventional paper bobbin The sound pressurefrequency characteristic of the type speaker is represented by a solid line A. As apparent from
FIG. 6, in the cone type speaker using the bobbin 3 according to the present embodiment, the
drop in sound pressure is effectively suppressed in the high frequency region, and in the wide
frequency region compared with the conventional one. It is possible to realize a flat sound
pressure.
[0049]
The bobbin 3 according to the present embodiment is large in rigidity and high in heat resistance
because the number of hydrogen bonds between fibers forming the paper and in the fibers is
increased by zinc chloride solution processing. Therefore, even if a large current is input to the
voice coil, the bobbin 3 is not deformed due to the generated heat or the like, adhesion peeling
between the bobbin 3 and the conducting wire 4 and winding deviation of the conducting wire 4
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do not occur. In addition, since the specific gravity of the bobbin material is small, the voice coil
vibrates faithfully according to the input audio current, and this vibration is transmitted to the
diaphragm, so that the maximum reproduction frequency is high and the reproduction range is
large. An effect such as enlargement is obtained.
[0050]
Third Embodiment Still another embodiment of the present invention will be described below
with reference to FIG. The present invention is not limited by this.
[0051]
First, a method of manufacturing a bobbin according to the present embodiment will be
described below.
[0052]
First, two rolls of kraft tape (paper) 6. 6 having a width of about 30 mm were made to be highly
rigid in the same manner as in the first embodiment.
Subsequently, the kraft tapes 6 and 6 are pulled up from the aqueous solution of zinc chloride
and dried, and then, as shown in FIG. The two tubes 8 are spirally attached to each other at an
angle to form a paper tube 8. This was cut into a predetermined length to obtain a bobbin
according to the present embodiment. The thickness of the produced bobbin was 80 μm.
[0053]
As a result of comparing the physical properties of the bobbin according to the present
embodiment with a conventional paper bobbin, the elastic modulus is 11.4 × 10 10 dyn / cm 2
to 16.4 × 10 10 dyn / cm 2, and the maximum usable temperature is 200 The temperature was
greatly improved from 240 ° C. to 240 ° C., respectively.
[0054]
The bobbin according to the present embodiment is used as a voice coil by winding a lead along
the outer periphery of the bobbin.
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[0055]
Fourth Embodiment Still another embodiment of the present invention will be described below.
The present invention is not limited by this.
[0056]
The bobbin according to the present embodiment is manufactured by the method described
below.
[0057]
First, beating-prepared kraft pulp was formed into a cylindrical paper pipe by a cylindrical
papermaking method, and the rigidity was enhanced in the same manner as in the first
embodiment.
Subsequently, the cylindrical paper pipe was pulled up from the aqueous solution of zinc
chloride, dried, and cut into a predetermined length to obtain a bobbin according to the present
embodiment.
The thickness of the produced bobbin was 100 μm.
[0058]
As a result of comparing the physical properties of the bobbin according to the present
embodiment with a conventional paper bobbin, the elastic modulus is 11.4 × 10 10 dyn / cm 2
to 13.4 × 10 10 dyn / cm 2, and the maximum usable temperature is 200 The temperature was
greatly improved from 240 ° C. to 240 ° C., respectively.
[0059]
The bobbin according to the present embodiment is used as a voice coil by winding a lead along
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the outer periphery of the bobbin.
[0060]
The bobbin according to the present invention does not have to be entirely made of paper, as
long as at least a part of it is made of paper.
For example, it may be a bobbin formed by combining members made of materials other than
paper, using paper as a base material, or a bobbin made of a material containing paper as one
component.
Further, the bobbin is not limited to one for a cone type speaker, and may be a dome-shaped or
horn type speaker voice coil bobbin.
[0061]
As described above, the diaphragm according to claim 1 of the present invention comprises
paper which is formed by absorbing and drying a zinc chloride solution at least in part.
[0062]
According to the above configuration, the paper obtained by absorbing and drying the zinc
chloride solution increases the number of hydrogen bonds acting between fibers in the paper and
in the fibers, and various physical properties such as rigidity, elastic modulus and heat resistance
Improve.
Therefore, if the above-mentioned paper is used as a diaphragm material, in addition to the
material properties which the paper originally has, which is generally low in cost, light in weight
and small in specific gravity, the diaphragm has large elastic modulus and bending rigidity. Can
be provided. That is, the diaphragm in which the deformation of the diaphragm and the
occurrence of split resonance are suppressed can be provided at low cost.
[0063]
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Therefore, by using the diaphragm according to the present invention, it is possible to
inexpensively provide a speaker excellent in various acoustic characteristics such as an excellent
sound pressure-frequency characteristic and a small distortion factor and a high high-resonance
frequency. Play an effect.
[0064]
As described above, the bobbin according to claim 2 of the present invention is configured to
include the paper obtained by absorbing and drying the zinc chloride solution at least in part.
[0065]
According to the above configuration, the paper obtained by absorbing and drying the zinc
chloride solution increases the number of hydrogen bonds acting between fibers in the paper and
in the fibers, and various physical properties such as rigidity, elastic modulus and heat resistance
Improve.
Therefore, a highly elastic bobbin can be provided inexpensively without deformation due to heat
or the like.
[0066]
In addition, the bobbin has material properties such as lightness, small specific gravity, and the
like which paper originally has, so that the weight of the voice coil can be reduced.
Therefore, the voice coil vibrates faithfully according to the input audio current, and the vibration
is transmitted to the diaphragm to obtain effects such as a high maximum reproduction
frequency and an expanded reproduction range. Be
[0067]
Therefore, by using the bobbin according to the present invention, it is possible to inexpensively
provide a speaker excellent in various acoustic characteristics such as excellent sound pressurefrequency characteristics and a small distortion factor and a high high-resonance frequency.
Play.
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