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JP2008193372

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This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
financial decisions, should not be based on machine-translation output.
DESCRIPTION JP2008193372
The present invention relates to a speaker diaphragm, a speaker, an electronic device, and a
device used in an audio device, and it is an object of the invention to make characteristics with
high accuracy and to make sound. According to the present invention, a diaphragm is formed by
injection molding a material in which a resin, an aramid pulp, and a microfibrillated aramid pulp
in which the aramid pulp is finely divided to a microfibrillated state is mixed to form a diaphragm
for a speaker. A configuration with which the freedom of setting of physical property values is
large, high reliability, high moisture resistance and high internal loss can be ensured, and a
diaphragm with excellent appearance and improved productivity and dimensional stability can be
realized. The [Selected figure] Figure 1
Speaker diaphragm, speaker using the same, electronic apparatus and apparatus using the
speaker
[0001]
The present invention relates to a speaker diaphragm used for various audio devices and video
devices, and electronic devices and devices such as speakers, stereo sets, and television sets
using the same.
[0002]
The prior art will be described with reference to FIG.
[0003]
FIG. 6 is a cross-sectional view of a conventional resin-made speaker diaphragm by injection
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molding.
[0004]
As shown in FIG. 6, the speaker diaphragm 16 is obtained by thermally dissolving resin pellets in
a mold whose shape is set in advance using a resin such as polypropylene and injection molding.
[0005]
As a kind of resin material by these injection molding, single materials, such as a polypropylene,
are generally used well.
[0006]
In addition to the above, there has been a blend type using resins of different types for the
purpose of adjusting physical property values as a diaphragm, that is, adjusting characteristics of
a speaker and sound quality.
[0007]
Furthermore, with regard to adjustment of physical property values that are difficult to adjust
with these resins, reinforcing materials such as mica were mixed to perform adjustment of
physical property values, and adjustment of characteristics as a speaker and sound quality.
[0008]
As prior art document information related to the invention of this application, for example,
Patent Document 1 is known.
JP-A-2-228197
[0009]
With respect to recent audio devices, video devices, and devices such as automobiles equipped
with these devices, performance has been dramatically improved in comparison with
conventional devices due to remarkable advances in digital technology.
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[0010]
With regard to the sound quality, low distortion, wide band, high dynamic range and further
realism have been achieved, and with regard to images also, remarkable performance
improvement has been achieved by the high definition and the appearance and spread of large
modules such as plasma displays. .
[0011]
Therefore, with the above-mentioned performance improvement of the electronic device, the
performance improvement of the speaker used for these electronic devices is strongly demanded
from the market.
[0012]
On the other hand, in the case of a speaker whose performance improvement is strongly
demanded by the market, it is indispensable to cope with the enhancement of the diaphragm
which occupies a large weight which determines the sound quality among the component parts
of the speaker.
[0013]
However, this diaphragm uses the method of manufacturing by traditional papermaking and the
method of injection molding and pressing of resin, and therefore, it is mainly a paper diaphragm
or a resin diaphragm, and while utilizing the respective features, it is used for its application It
has been used properly, but each has its own drawbacks.
[0014]
That is, in the case of a paper diaphragm, it is possible to mix aramid fibers, mica and the like
easily by wet mixing, so that physical property values can be set finely, and there is an advantage
that the freedom as a speaker characteristic and sound quality adjustment becomes large.
However, they have the disadvantages that they are inferior in moisture resistance and water
resistance, which are inherent disadvantages of paper, and that their production can not be
obtained unless a very large number of steps of papermaking are required.
[0015]
On the other hand, in the resin diaphragm obtained by injection molding, although moisture
resistance, water resistance and dimensional stability can be secured and productivity can be
improved, an inorganic filler such as mica is used to adjust physical properties, and therefore
uniform. However, it has the disadvantage that the characteristic as a speaker and the adjustment
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range of the sound quality become very narrow.
[0016]
The present invention solves the above-mentioned problems, the characteristics as a speaker, the
freedom of adjustment of sound quality is large, the moisture resistance, the water resistance
reliability and the dimensional stability can be secured, the appearance can be excellent, and the
productivity can be improved. It is an object of the present invention to provide a diaphragm.
[0017]
In order to achieve the above object, the present invention is a diaphragm for a speaker
comprising a resin, an aramid pulp, and a microfibrillated aramid pulp in which the aramid pulp
is finely pulverized to a microfibrillated state, and the diaphragm is injection molded. Obtained by
[0018]
With this configuration, the degree of freedom in setting the physical property values of the
diaphragm is increased by maintaining high elasticity and high internal loss of the aramid fiber,
and furthermore, the moisture resistance and water resistance reliability by the resin can be
secured, and dimensional stability by injection molding Thus, a speaker diaphragm excellent in
productivity can be obtained.
[0019]
As described above, according to the present invention, a resin, an aramid pulp, and a
microfibrillated aramid pulp finely divided to a microfibrillated state are formed by injection
molding.
[0020]
By this configuration, the entanglement between the aramid fibers is improved, the high elastic
modulus which is a feature of the aramid fibers can be further increased, and by using the pulp,
high internal loss can be maintained, and the physical property value setting of the diaphragm is
free The degree is increased, the humidity resistance and the strength can be secured, and a
diaphragm excellent in appearance can be obtained.
[0021]
In addition, by obtaining the diaphragm by injection molding, it is possible to obtain a diaphragm
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with improved productivity and dimensional stability.
[0022]
In addition, by selecting the resin and reinforcement material that is a mixed material from
among a wide variety of materials and setting the blending ratio appropriately, it is possible to
obtain high-quality characteristics and sound quality that were not possible in the past.
Adjustment is possible.
[0023]
Hereinafter, embodiments of the present invention will be described using the drawings.
[0024]
First Embodiment The first to eighteenth aspects of the present invention will be described with
reference to the first embodiment.
[0025]
FIG. 1 shows a cross-sectional view of a diaphragm according to an embodiment of the present
invention, and FIG. 2 shows an enlarged cross-sectional view of the diaphragm according to an
embodiment of the present invention.
[0026]
As shown in FIGS. 1 and 2, the diaphragm 1 is formed by injection molding of a material in which
a resin 1A, an aramid pulp 1B and a microfibrillated aramid pulp 1C finely divided to a
microfibrillated state are mixed.
Here, the aramid pulp refers to a pulp that is not composed of cellulose, but has a shape like a
pulp in which a plurality of aramid fibers are gathered to form a pulp.
[0027]
The microfibrillated aramid pulp 1C is entangled with the aramid pulp 1B, and as a result, the
entanglement of fibers is improved, and a diaphragm with higher strength and higher rigidity can
be obtained.
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[0028]
Generally, as the aspect ratio (fiber length / fiber diameter) of the fiber increases, the elastic
modulus tends to improve.
In the case of aramid fibers, since the fibers themselves are rigid, the fiber diameter can be
reduced to 3 μm or less by microfibrillation, and as a result, the modulus of elasticity is
significantly increased by the microfibrillated aramid pulp.
Therefore, a highly elastic diaphragm can be obtained while maintaining high internal loss.
[0029]
As a material of the diaphragm 1, a crystalline or amorphous olefin resin is used for the resin 1A.
[0030]
By using an olefin resin, the moldability can be improved, and by using crystalline and noncrystalline resin materials properly depending on the application, it is possible to satisfy the
optimum physical property value as a resin material. It becomes possible.
[0031]
This time, among these, resin 1A explains the example at the time of using polypropylene.
[0032]
Also, although polypropylene is generally easily available and injection molding is easy, the
present invention is not limited to this resin, and it is freely used properly, such as using other
resins according to the desired characteristic value. can do.
[0033]
For example, when high heat resistance and high solvent resistance are required, engineering
plastics suitable for the application can also be used.
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[0034]
Here, the aramid fiber can reproduce bright tones with a clear sense, and can suppress dark and
uniform tones unique to resins.
[0035]
In general, the modulus of elasticity of the fiber improves as the aspect ratio (fiber length / fiber
diameter) increases.
In particular, in the case of rigid fibers such as aramid fibers, this tendency is noticeable because
they have sufficient strength even if the fiber diameter is small.
Therefore, the microfibrillated aramid pulp having a fiber diameter of 3 μm or less has a large
aspect ratio, and a diaphragm having a high elastic modulus can be obtained.
[0036]
Furthermore, by including chopped fiber-like aramid fibers having a uniform fiber length, it is
possible to make the film more elastic without changing the timbre.
In addition, the presence of aramid pulp makes it possible to mix without compatibilizer.
[0037]
In addition, the fiber length of the chopped fiber-like aramid fiber is configured to be 0.3 mm to
6 mm or less.
[0038]
Here, when the fiber length of the chopped fiber-like aramid fiber is shorter than 0.3 mm, the
effect of the aramid fiber can not be efficiently obtained, and an increase in elastic modulus due
to mixing can not be expected.
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[0039]
On the other hand, if it is longer than 6 mm, a poor dispersion is likely to occur due to secondary
aggregation resulting from intertwining of fibers, so a long kneading process with the resin is
required, or a lump of aramid fiber on the surface of the diaphragm, A mass of fiber appears to
cause problems in productivity and quality such as impairing the appearance.
[0040]
Preferably, a chopped fiber-like aramid fiber having a fiber length of 3 mm or less is mixed. If the
fiber length is longer than this, it becomes difficult to form the diaphragm thin.
[0041]
In addition, by combining and using chopped fiber-like aramid fibers with long fibers having a
fiber length of 1.5 mm or more and short fibers having a fiber length less than 1.5 mm,
resonance can be mitigated and fine sound quality Adjustment is possible.
[0042]
Furthermore, if you want to strengthen the diaphragm, add some accents to the sound, or adjust
the sound pressure frequency characteristics by adjusting the sound pressure frequency
characteristics, mix mica, talc, cellulose fibers, carbon fibers as reinforcements. Can also be
configured.
[0043]
In this case, if mica is mixed into the reinforcing material, the elastic modulus can be increased.
Also, mixing talc can increase internal loss.
Furthermore, by mixing the cellulose fiber, the cellulose fiber and the aramid fiber are entangled,
and the internal loss can be increased without reducing the elastic modulus.
Moreover, the effect of raising an elastic modulus is acquired by mixing high-strength fiber like
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carbon fiber.
[0044]
In particular, by using cellulose fiber as bamboo fiber, rigid physical properties of bamboo can be
imparted, and the elastic modulus is increased.
In addition, by using microfibrillar bamboo pulp in which a portion of bamboo pulp is finely
pulverized to a microfibrillar state, the bonding strength between fibers can be further increased
and the elastic modulus can be increased.
[0045]
In addition, a fluid modifier may be mixed.
As such a modifier, for example, flowable paraffin and calcium stearate can be used.
In particular, fatty acids having an amino group are desirable. By using stearic acid amide or oleic
acid amide, it is possible to thin the diaphragm formed by injection molding.
[0046]
Furthermore, the mixing ratio of aramid pulp to the resin of the present invention is set to 5 wt%
to 50 wt%.
By this configuration, it is possible to efficiently draw out the effects of kneading with the resin
and to improve the productivity and the quality.
[0047]
Here, when the mixing ratio of aramid fibers is less than 5% by weight, the effect of aramid fibers
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hardly appears.
[0048]
On the other hand, if it is more than 50% by weight, the kneading step becomes long, and since
injection molding becomes difficult, productivity and dimensional stability decrease, and the
degree of freedom in shape decreases.
[0049]
Also, the aramid fibers finely divided to the microfibrillar state are constituted as 5% by weight to
20% by weight.
[0050]
Here, when the content of the aramid fibers finely divided to the microfibrillated state is less than
5% by weight, it is difficult to form the network between the fibers finely divided to the
microfibrillated state, and the strength and elastic modulus increase. I can not hope.
Also, when it is more than 20% by weight, no remarkable improvement in elastic modulus is
observed.
[0051]
Then, by combining the above-described materials, it is possible to freely adjust the physical
property value of the diaphragm with high precision, and it is possible to realize desired
characteristics and sound quality.
[0052]
As described above, according to the present invention, a material including a resin, an aramid
pulp, and a microfibrillated aramid pulp obtained by mixing the aramid pulp into a
microfibrillated state is injected and molded to form a diaphragm for a speaker. To obtain a
diaphragm which has high elastic modulus and high internal loss, which are features of aramid
fibers, which has a high degree of freedom in setting physical property values of the plate, is
excellent in moisture resistance reliability and appearance, and can improve productivity and
dimensional stability. Can.
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[0053]
Second Embodiment The invention according to the nineteenth aspect of the present invention
will be described below with reference to the second embodiment.
[0054]
FIG. 3 shows a cross-sectional view of a loudspeaker according to an embodiment of the present
invention.
[0055]
As shown in FIG. 3, the magnetized magnet 2 is sandwiched between the upper plate 3 and the
yoke 4 to constitute an internal magnetic circuit 5.
[0056]
The frame 7 is coupled to the yoke 4 of the magnetic circuit 5.
The outer periphery of any one of the diaphragms 1 according to claims 1 to 18 is bonded to the
peripheral portion of the frame 7 via an edge 9.
Then, one end of the voice coil 8 is coupled to the central portion of the diaphragm 1, and the
other end is coupled to be fitted into the magnetic gap 6 of the magnetic circuit 5.
[0057]
Although the above has described the speaker 10 having the internal magnet type magnetic
circuit 5, the present invention is not limited to this, and may be applied to a speaker having an
external magnet type magnetic circuit.
[0058]
With this configuration, as described in the first embodiment, the degree of freedom in adjusting
the characteristics and sound quality is large, and the high modulus of elasticity and high internal
loss which are the features of the aramid fiber are obtained, and the moisture resistance
reliability and strength can be ensured. It is possible to realize a speaker with excellent
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appearance and high productivity.
[0059]
Third Embodiment The invention according to the twentieth aspect of the present invention will
be described with reference to the third embodiment.
[0060]
FIG. 4 is an external view of an audio mini-component system which is an electronic device
according to an embodiment of the present invention.
[0061]
As shown in FIG. 4, the speaker 10 of the present invention is incorporated in an enclosure 11 to
form a speaker system, and an amplifier 12 as amplification means for an electric signal input to
the speaker and a source input to the amplifier 12 And an audio mini-component system 14
which is an electronic device.
[0062]
With this configuration, it is possible to realize an electronic device capable of producing
characteristics with high accuracy, making sound, and designing that could not be realized
conventionally.
[0063]
Fourth Embodiment The fourth embodiment of the present invention will be described below in
particular for the twenty-first aspect of the present invention.
[0064]
FIG. 5 shows a cross-sectional view of an automobile 15 which is an apparatus according to an
embodiment of the present invention.
[0065]
As shown in FIG. 5, the speaker 10 of the present invention is incorporated in a rear tray or a
front panel and used as a part of a car navigation system or a car audio system to constitute an
automobile 15.
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[0066]
With this configuration, the characteristics of the aramid fiber of the speaker 10 can be made to
have high precision characteristics, the sound can be made, and the design can be made to
improve the freedom of acoustic design of a device such as an automobile equipped with the
speaker 10 be able to.
[0067]
The speaker diaphragm, the speaker, the electronic device, and the device according to the
present invention can be applied to an electronic device such as an audiovisual device and an
information communication device which needs high-quality characteristics and needs sound
creation, and further to a device such as an automobile.
[0068]
Cross-sectional view of speaker diaphragm in one embodiment of the present invention Crosssectional enlarged view of speaker diaphragm in one embodiment of the present invention Crosssectional view of speaker in one embodiment of the present invention FIG. 16 is an external view
of an electronic device in the present invention, and a sectional view of an apparatus according to
an embodiment of the present invention, and a sectional view of a conventional speaker
diaphragm.
Explanation of sign
[0069]
DESCRIPTION OF SYMBOLS 1 diaphragm 1A resin 1B aramid pulp 1C micro fibrillated aramid
pulp 2 magnet 3 upper plate 4 yoke 5 magnetic circuit 6 magnetic gap 7 frame 8 voice coil 9
edge 10 speaker 11 enclosure 12 amplifier 13 player 14 mini component system 15 automobile
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