JP2009089302

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DESCRIPTION JP2009089302
The present invention relates to a speaker diaphragm, a speaker, an electronic device, and an
apparatus used for an audio device, and it is an object of the present invention to provide a highquality speaker diaphragm with less environmental load. . In order to achieve this object,
according to the present invention, by forming a diaphragm for a speaker from resin of plant
material, natural mineral and plant fiber, the heat resistance and the strength are high, and the
appearance is excellent. It is configured to be able to realize a high-quality speaker diaphragm
with less environmental load. [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
molding.
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[0004]
As shown in FIG. 6, the speaker diaphragm 31 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]
However, they have a large environmental impact because polypropylene, which is the base
resin, is derived from petroleum.
[0009]
Therefore, in recent years, with the movement of de-petrochemical work, studies using plantderived polylactic acid as a resin have been actively conducted.
[0010]
As prior art document information related to the invention of this application, for example,
Patent Document 1 is known.
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JP, 2005-260546, A
[0011]
In the speaker diaphragm using the conventional polylactic acid, high reliability can not be
realized due to insufficient heat resistance, and problems in sound quality have been left in terms
of insufficient strength and low elastic modulus.
[0012]
An object of the present invention is to solve the above-mentioned problems, and to provide a
high-quality speaker diaphragm with less environmental load.
[0013]
In order to achieve the above object, the present invention constitutes a speaker diaphragm from
resin of plant material, natural mineral and plant fiber.
[0014]
With this configuration, natural minerals and plant fibers promote the crystallization of polylactic
acid, and have the effect of improving heat resistance, which is a problem.
In addition, the sound speed of the speaker diaphragm is increased in order not only to promote
crystallization but also to improve the elastic modulus.
Plant fibers also have the effect of improving internal loss.
[0015]
Therefore, it becomes a speaker diaphragm with high sound quality and small environmental
load.
[0016]
As described above, according to the present invention, the diaphragm for the speaker is
configured from the resin of the plant raw material, the natural mineral and the plant fiber.
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[0017]
With this configuration, it is possible to improve heat resistance by promoting crystallization,
which is a problem of polylactic acid.
[0018]
In addition, both natural minerals and plant fibers have the effect of improving the elastic
modulus, and plant fibers also have the effect of improving the internal loss, so distortion and
resonance can be suppressed.
[0019]
Therefore, the diaphragm for speakers comprised from resin of a plant raw material, natural
mineral, and plant fiber can be made into a high-sound quality diaphragm for speakers with less
environmental load than the conventional resin diaphragm.
[0020]
Hereinafter, embodiments of the present invention will be described using the drawings.
[0021]
(Embodiment 1) The inventions according to claims 1 to 11 of the present invention will be
described with reference to Embodiment 1 below.
[0022]
FIG. 1 shows a cross-sectional view of a diaphragm according to an embodiment of the present
invention, and FIG. 2 shows a plan view of the diaphragm according to an embodiment of the
present invention.
[0023]
As shown in FIG. 1 and FIG. 2, the diaphragm 1 uses resin of a plant raw material as a base resin,
and polylactic acid 1A with a high bending elastic modulus is preferable for selection of resin.
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Natural minerals and plant fibers are uniformly dispersed in this polylactic acid 1A.
Here, preferably, it is preferable to select mica 1B as a natural mineral and bamboo fiber 1C as a
plant fiber.
The diaphragm 1 is formed by injection molding a material in which mica 1B and bamboo fiber
1C are uniformly dispersed in the polylactic acid 1A.
[0024]
With this configuration, the mica 1B and the bamboo fiber 1C promote the crystallization of the
polylactic acid 1A, so that the injection molding cycle can be shortened, and the heat resistance
which is the problem is improved.
In addition, since bamboo fiber 1C is hard and has flexibility, it has an effect of improving the
elastic modulus and an effect of improving the internal loss.
[0025]
As a result, it becomes a speaker diaphragm having a high elastic modulus and a high internal
loss, and the speaker using this has higher sound quality.
[0026]
Moreover, bamboo has a large deodorizing effect and does not have an odor specific to plant
fibers, so it can be widely used in car speakers and indoor audio.
[0027]
In addition to the effect of adjusting physical properties to improve the sound quality, bamboo
fiber can increase the plant density, and can improve the sound quality while reducing the
environmental load.
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The term "vegetality" as used herein refers to the percentage by weight of the material
comprising plant material, and refers to the total percentage by weight of the resin of plant
material and the plant fiber contained in the speaker diaphragm.
In the case of petroleum raw materials, carbon dioxide generated at the time of incineration
disposal of the diaphragm means that carbon dioxide is newly generated as the reason that
environmental load decreases as the plant density increases, but plants are carbon dioxide by
photosynthesis. In order to absorb the carbon dioxide, it is possible to reduce net carbon dioxide
emissions because a part of the carbon dioxide generated at the time of incineration disposal
contains the carbon dioxide originally held by the plant.
[0028]
Therefore, the speaker diaphragm made of polylactic acid, mica and bamboo fiber is
environmentally friendly and can realize better sound quality.
[0029]
The fiber length of the bamboo fiber to be mixed is preferably 0.2 mm or more and 5 mm or less.
If the fiber length of bamboo fiber is shorter than 0.2 mm, the effect of bamboo fiber can not be
efficiently obtained, and a high elastic modulus can not be expected.
If the fiber length of bamboo fiber is longer than 5 mm, the appearance will be impaired when
the diaphragm is made thin.
Therefore, in order to obtain a high performance and high quality speaker diaphragm, it is
preferable to select a fiber length of bamboo fiber of 0.2 mm or more and 5 mm or less.
[0030]
The amount of bamboo fiber mixed is preferably 5% by weight or more and 55% by weight or
less, and more preferably 10% by weight or more and 30% by weight or less.
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[0031]
When the content of bamboo fiber is 5% by weight or less, the effect of bamboo fiber does not
appear remarkably, and when it is 55% by weight or more, uniform dispersion of bamboo fiber in
resin becomes difficult.
[0032]
In particular, when bamboo fibers of 30% by weight or more are included, it is difficult to obtain
a diaphragm having a surface thickness of 0.3 mm or less by injection molding because the
flowability of the resin is low.
[0033]
Furthermore, it is more preferable that the bamboo fiber further includes bamboo fiber refined to
a microfibrillated state with an average fiber diameter of 10 μm or less.
[0034]
By the presence of bamboo fibers refined to the microfibrillar state, the entanglement of bamboo
fibers becomes strong, and thus the strength is improved.
Therefore, the elastic modulus is also improved, and higher sound quality can be realized.
[0035]
Also, in general, the higher the aspect ratio (L / D), which is the ratio of fiber length L to fiber
diameter D, the higher the elasticity, and the bamboo fiber which has been made fine to the
microfibrillated state has a high aspect ratio and therefore a high elastic modulus Can expect.
[0036]
In addition, the presence of bamboo fibers partially refined to a microfibrillated state also has the
effect of strengthening the bonds between the fibers, which are synergistic to provide a high
elastic modulus.
[0037]
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Also, if you want to make bamboo fiber more natural and brighter, bamboo powder may be used
for some or all of the bamboo fibers.
If the content of bamboo fiber mentioned above exceeds 30% by weight, the defect that molding
becomes difficult is also alleviated by using bamboo powder, and the total content of bamboo
fiber and bamboo powder which is not in powder form is 55% by weight Injection molding is
easily possible in the following cases.
[0038]
Moreover, since the degree of planting of the material is increased, it is possible to obtain a
speaker diaphragm with less environmental load.
The term "plant degree" as used herein refers to the total weight of plant raw resin produced
from corn and plant fibers such as bamboo fiber, and how to reduce the emission of carbon
dioxide, which is a greenhouse gas, without using petroleum-derived materials It will be an
indication of what you can do.
[0039]
Further, the elastic modulus can be further improved by further adding a carbonized material,
and in particular, by using bamboo charcoal, the elastic modulus can be increased without
lowering the degree of plant.
[0040]
In addition, bamboo charcoal usually plays the role of a carbon-based pigment used in a speaker
diaphragm for a black-based color, and it is possible not only to improve the sound quality, but
also to have a high-quality appearance.
[0041]
The bamboo charcoal referred to here refers to a granular material obtained by cutting a bamboo
material to a suitable size in advance and carbonizing it at a high temperature of about 800 ° C.
and then grinding it.
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[0042]
Further, it may further contain a conventional petroleum resin.
In particular, polypropylene is preferable for petroleum resins.
Polypropylene itself has a large internal loss and a low specific gravity, so the weight of the
diaphragm can be reduced and the internal loss can be increased.
[0043]
Examples of the subclaims of the present invention will be described below, but this example
does not limit the scope of the present invention.
[0044]
Example 1 Melt-kneaded resin having a composition of polylactic acid content of 25% by weight,
mica content of 15% by weight, bamboo fiber content of 15% by weight, and polypropylene
content of 45% by weight Pellets were produced and injection molded at a molding temperature
of 200 ° C. to obtain a speaker diaphragm of 16 cm in diameter.
[0045]
Comparative Example 1 A speaker diaphragm was obtained in the same manner as in Example 1
using only polylactic acid.
[0046]
Comparative Example 2 A speaker diaphragm was obtained in the same manner as in Example 1
with a composition having a content of polypropylene of 85% by weight and a content of mica of
15% by weight.
[0047]
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<Evaluation of Physical Properties> The specific gravity of the above-mentioned diaphragm was
measured.
And the sample of 32 mm x 5 mm size which is one part was extracted, and the elastic modulus,
the internal loss, and the sound velocity were measured.
The results of these measurements are shown in the table below.
[0048]
[0049]
From the said table ¦ surface, it is clear compared with the diaphragm for speakers of the
comparative example 1 that the diaphragm for speakers of Example 1 is improving sound speed
and internal loss.
[0050]
Further, the speaker diaphragm of Comparative Example 2 is a diaphragm in which 15% by
weight of mica is contained as a reinforcing material in polypropylene of petroleum-derived resin
which is a conventional industrial product, but compared with Comparative Example 2 with
sound velocity Internal losses are improving.
[0051]
<Heat resistance evaluation> The heat resistance was evaluated by leaving it to stand in a
thermostat for 240 hours in an atmosphere at a temperature of 100 ° C. for Example 1,
Comparative Example 1 and Comparative Example 2.
[0052]
Although corrugation was confirmed on the outer periphery of the diaphragm only in
Comparative Example 1, no deformation was observed in Example 1 and Comparative Example 2.
[0053]
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As described above, according to the present invention, by constituting the speaker diaphragm
from the resin of the plant raw material, the natural mineral and the plant fiber, it is possible to
improve the insufficient heat resistance and the insufficient strength which are the disadvantages
of the conventional polylactic acid. Sound velocity and internal loss are improved.
In addition to the improvement in sound quality, the diaphragm is made of a material having a
higher degree of plantiness than in the prior art, so it is possible to obtain a high-quality speaker
diaphragm with less environmental load.
[0054]
Second Embodiment The second embodiment of the present invention will be used to explain the
invention set forth in the twelfth aspect of the present invention.
[0055]
FIG. 3 shows a cross-sectional view of a loudspeaker according to an embodiment of the present
invention.
[0056]
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.
[0057]
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 any one of claims 1 to 11 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.
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[0058]
The above has described the speaker having the internal magnet type magnetic circuit 5, but the
present invention is not limited to this, and may be applied to a speaker having the external
magnet type magnetic circuit.
[0059]
With this configuration, as described in the first embodiment, it is possible to realize a speaker
with high sound quality with less environmental load.
[0060]
Third Embodiment The third embodiment of the present invention will be used to explain the
invention set forth in the thirteenth aspect of the present invention.
[0061]
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.
[0062]
The speaker 10 is incorporated in the enclosure 11 to constitute a speaker system 21.
The amplifier 12 includes an amplification circuit of an electrical signal to be input to the
speaker system 21.
The operation unit 13 such as a player outputs the source input to the amplifier 12.
Thus, the audio mini-component system 14 which is an electronic device includes the amplifier
12, the operation unit 13, and the speaker system 21.
The amplifier 12, the operation unit 13, and the enclosure 11 are main parts of the mini
component system 14.
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That is, the speaker 10 is mounted on the main body of the mini component system 14.
Further, the voice coil 8 of the speaker 10 is supplied with power from the amplifier 12 of the
main body and emits sound from the diaphragm 1.
With this configuration, it is possible to obtain the mini component system 14 which has high
environmental quality and high quality with less environmental load which can not be realized
conventionally.
[0063]
In addition, although the mini component system 14 for audio was demonstrated as an
application to the apparatus of the speaker 10, it is not limited to this.
Application to portable portable audio devices and game devices is also possible.
Furthermore, the present invention can be widely applied to and developed in electronic devices
such as image devices such as liquid crystal televisions and plasma display televisions,
information communication devices such as mobile phones, and computer related devices.
[0064]
Fourth Embodiment The fourth embodiment of the present invention will be described in the
following.
[0065]
FIG. 5 shows a cross-sectional view of an automobile 15 which is an apparatus according to an
embodiment of the present invention.
[0066]
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
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automobile 15.
[0067]
With this configuration, it is possible to utilize the features of the speaker 10 and reduce the
environmental load while achieving an excellent design with high sound quality, and also reduce
the environmental load of devices such as automobiles equipped with the speaker 10 be able to.
[0068]
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 or an
information communication device which requires a high sound quality speaker with reduced
environmental load and a device such as an automobile. it can.
[0069]
Cross-sectional view of speaker diaphragm in one embodiment of the present invention Top view
of diaphragm for speaker in one embodiment of the present invention Cross-sectional view of
speaker in one embodiment of the present invention in one embodiment of the present invention
External view of electronic device Cross-sectional view of device according to one embodiment of
the present invention Cross-sectional view of a conventional speaker
Explanation of sign
[0070]
Reference Signs List 1 diaphragm 1A polylactic acid 1B mica 1C bamboo fiber 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 operation unit 14 mini component system 15 automobile
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