JP5023853B2 - Speaker diaphragm, speaker using the same, and electronic device and apparatus using the speaker - Google Patents

Description

  The present invention relates to a speaker diaphragm used in various audio equipment and video equipment, and to electronic equipment and devices such as a speaker, a stereo set, and a television set using the diaphragm.

  A conventional technique will be described with reference to FIG.

  FIG. 6 is a cross-sectional view of a resin speaker diaphragm made by conventional injection molding.

  As shown in FIG. 6, the speaker diaphragm 7 was obtained by using resin such as polypropylene and injection-molding resin pellets in a pre-set mold.

  As a kind of the resin material by these injection moldings, a single material such as polypropylene is generally often used.

  In addition, for the purpose of adjusting physical property values as a diaphragm, that is, adjusting characteristics and sound quality as a speaker, there is a blend type using different types of resins.

  Furthermore, with respect to adjustment of physical property values that are difficult to adjust with these resins, reinforcing material such as mica is mixed to adjust the physical property values to adjust the characteristics and sound quality as a speaker.

  However, since the base resin is polypropylene, and this polypropylene is derived from petroleum, it has a large environmental load.

  For this reason, in recent years, studies have been actively conducted on the use of polylactic acid derived from plants as a resin in the movement of depetrochemicals.

For example, Patent Document 1 is known as prior art document information relating to the invention of this application.
JP 2005-260546 A

  Conventional speaker diaphragms using polylactic acid cannot achieve high reliability due to insufficient heat resistance, and also have problems in sound quality from the viewpoint of insufficient strength and low elastic modulus.

  An object of the present invention is to solve the above-mentioned problems and to provide a high-quality speaker diaphragm with a low environmental load.

In order to achieve the above object, the present invention is a speaker diaphragm that is composed of polylactic acid extracted from a plant and bamboo charcoal, and the bamboo charcoal is carbonized at a high temperature. That is, all of the constituent materials are plant-derived materials, not petroleum-derived materials.

  With this configuration, the heat resistance, which is a problem of polylactic acid, is improved, and the elastic modulus is also improved by the effect of bamboo charcoal, so that a diaphragm for a speaker with high rigidity becomes possible. Therefore, it can be set as the speaker diaphragm with high sound quality and small environmental load.

As described above, the present invention is composed of polylactic acid extracted from a plant and bamboo charcoal, and the bamboo charcoal is a speaker diaphragm carbonized at a high temperature.

  With this configuration, the heat resistance, which is a problem of polylactic acid, is improved, and the elastic modulus is also improved by the effect of bamboo charcoal, so that a diaphragm for a speaker with high rigidity becomes possible.

  Bamboo charcoal also serves as an alternative to the colorant and can achieve a high-quality appearance.

  Therefore, the loudspeaker diaphragm composed of polylactic acid extracted from plants and bamboo charcoal obtained by carbonizing bamboo at high temperature is heat-resistant and does not use chemical substances derived from petroleum. In addition, it is possible to obtain an effect that it is excellent in appearance quality and environmentally friendly.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1)
The invention according to the first to sixth aspects of the present invention will be described below with reference to the first embodiment.

  FIG. 1 is a sectional view of a diaphragm according to an embodiment of the present invention, and FIG. 2 is a plan view of the diaphragm according to an embodiment of the present invention.

  As shown in FIG. 1 and FIG. 2, the diaphragm 27 is formed by injection-molding a material in which bamboo charcoal 27B is uniformly dispersed in polylactic acid 27A using polylactic acid 27A extracted from a plant as a base resin. ing.

  With this configuration, the heat resistance that has been a problem is improved. Bamboo charcoal also has the role of improving the elastic modulus, which improves the sound quality. In addition, it is possible to achieve a high-quality appearance without using a carbon-based pigment as used in a conventional black-colored speaker diaphragm.

After carbonization here means a high temperature under about 800 ° C. by cutting bamboo to advance appropriate size and bamboo charcoal, it refers to a particulate material obtained by grinding.

  In addition, bamboo fiber may be mixed when the weight of the diaphragm is reduced to increase the elastic modulus. Bamboo fiber not only improves the elastic modulus, but also increases internal loss and heat resistance.

  Moreover, the fiber length of the bamboo fiber to mix is 0.2 mm or more and 3 mm or less is desirable. By using bamboo fiber within this fiber length range, the effect when combined with polylactic acid 27A is efficiently exhibited.

  When the fiber length of the bamboo fiber is shorter than 0.2 mm, the effect of the bamboo fiber cannot be obtained efficiently and a high elastic modulus cannot be expected.

  On the other hand, when the length is longer than 3 mm, poor dispersion tends to occur due to secondary aggregation resulting from the entanglement of bamboo fibers. Therefore, a long time is required for kneading with polylactic acid 27A. Alternatively, bamboo fiber aggregates appear on the surface of the diaphragm 27 and the appearance is impaired. Thus, productivity and quality are reduced.

  Further, the amount of bamboo fiber to be mixed is preferably 5% by weight or more and 55% by weight or less, more preferably 10% by weight or more and 30% by weight or less.

  If the bamboo fiber is 5% by weight or less, the effect of the bamboo fiber does not appear remarkably, and if it is 55% by weight or more, it is difficult to uniformly disperse the bamboo fiber in the resin.

  In particular, when 30% by weight or more of bamboo fiber is included, the fluidity of the resin is low, so that it is difficult to obtain a diaphragm having a surface thickness of 0.3 mm or less by injection molding.

  Moreover, the bamboo fiber may be refined | miniaturized to a microfibril state.

  The presence of bamboo fibers refined to the microfibril state increases the strength of the bamboo fibers because the entanglement of the bamboo fibers becomes stronger. Therefore, the elastic modulus is also improved, and higher sound quality can be realized.

  Moreover, it is desirable that the average fiber diameter of the bamboo fiber refined to the microfibril state is 10 μm or less.

  In general, the fiber has higher elasticity when the aspect ratio (L / D), which is the ratio of the fiber length L to the fiber diameter D, is higher, and the bamboo fiber that has been refined to the microfibril state has a higher aspect ratio, so a higher elastic modulus can be expected. .

  In addition, the presence of bamboo fibers that are partially refined to a microfibril state also has the effect of strengthening the bond between the fibers, and these synergistically increase the elastic modulus.

  In addition, when it is desired to increase the bamboo fiber to make a more natural and bright tone, bamboo powder may be used for a part or all of the bamboo fiber. The above-mentioned disadvantage that molding becomes difficult when the bamboo fiber content exceeds 30% by weight is reduced by using bamboo powder, and the total content of bamboo fiber and bamboo powder not in powder form is 55% by weight. In this case, injection molding can be easily performed. Moreover, when the content rate of bamboo fiber exceeds 50%, it becomes possible to incinerate and dispose as bamboo instead of landfill at the time of disposal.

  Examples of the present invention will be described below, but these examples do not limit the scope of the present invention.

Example 1
A resin pellet is prepared by melting and kneading with a composition of polylactic acid content of 90% by weight and bamboo charcoal content of 10% by weight, and injection molding is performed at a molding temperature of 200 ° C. to obtain a diaphragm for a speaker having a 16 cm aperture. It was.

(Example 2)
A speaker diaphragm was obtained in the same manner as in Example 1 with a composition having a polylactic acid content of 80% by weight, bamboo charcoal content of 5% by weight, and bamboo fiber content of 15% by weight.

(Comparative Example 1)
A speaker diaphragm was obtained in the same manner as in Example 1 using only polylactic acid.

(Comparative Example 2)
A speaker diaphragm was obtained in the same manner as in Example 1 with a composition having a polypropylene content of 80% by weight and a mica content of 20% by weight.

<Physical property evaluation>
The specific gravity of the diaphragm was measured. Then, a sample having a size of 32 mm × 5 mm, which is a part of the sample, was extracted, and the elastic modulus, internal loss, and sound velocity were measured. These measurement results are shown in the table below.

  From this table, it is clear that the loudspeaker diaphragm of the example is improved in sound speed and internal loss as compared with the loudspeaker diaphragm of Comparative Example 1, and tends to have higher sound quality.

  The speaker diaphragm of Comparative Example 2 is a diaphragm containing 20% by weight of mica as a reinforcing material in polypropylene of petroleum-derived resin, which is a conventional industrial product. Since the internal loss is substantially equal, the speaker diaphragm of the example is considered to be a high-quality speaker diaphragm with reduced environmental load because it does not use petroleum-derived materials.

<Heat resistance evaluation>
The heat resistance of Example 1, Example 2, Comparative Example 1, and Comparative Example 2 was evaluated by allowing them to stand in a constant temperature bath for 240 hours in an atmosphere at a temperature of 100 ° C.

  Only in Comparative Example 1, the outer periphery of the diaphragm was corrugated and deformation was confirmed, but no deformation was observed in Example 1, Example 2, and Comparative Example 2.

  As described above, the present invention can improve the lack of heat resistance and strength, which are disadvantages of conventional polylactic acid, by constructing the diaphragm for speaker from polylactic acid extracted from plants and bamboo charcoal, Internal loss is also improved. In addition, bamboo charcoal has the effect of a coloring material, and a high-quality appearance is possible. Furthermore, since no chemical substance derived from petroleum is used, an environmentally friendly high sound quality diaphragm for a speaker can be obtained.

(Embodiment 2)
The second aspect of the present invention will be described below with reference to the seventh aspect of the present invention.

  FIG. 3 shows a cross-sectional view of a speaker according to an embodiment of the present invention.

  As shown in FIG. 3, a magnetized magnet 21 is sandwiched between an upper plate 22 and a yoke 23 to constitute an internal magnet type magnetic circuit 24.

  A frame 26 is coupled to the yoke 23 of the magnetic circuit 24. The outer periphery of any one of the diaphragms 27 according to claims 1 to 6 is bonded to the peripheral edge of the frame 26 via an edge 29. One end of the voice coil 28 is coupled to the central portion of the diaphragm 27 and the opposite end is coupled so as to fit into the magnetic gap 25 of the magnetic circuit 24.

  In the above, the speaker having the inner magnet type magnetic circuit 24 has been described. However, the present invention is not limited to this, and the present invention may be applied to a speaker having an outer magnet type magnetic circuit.

  With this configuration, as described in Embodiment 1, it is possible to realize a high sound quality speaker with a small environmental load.

(Embodiment 3)
Hereinafter, the invention according to claim 8 of the present invention will be described with reference to the third embodiment.

  FIG. 4 is an external view of an audio minicomponent system that is an electronic apparatus according to an embodiment of the present invention.

  The speaker 10 is incorporated in the enclosure 11 to constitute a speaker system 21. The amplifier 12 includes an amplification circuit for an electric signal input to the speaker system 21. An operation unit 13 such as a player outputs a source input to the amplifier 12. As described above, the audio mini-component system 14 that 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 body units of the mini component system 14. That is, the speaker 10 is attached to the main body of the mini component system 14. The voice coil 28 of the speaker 10 is supplied with power from the amplifier 12 of the main body and emits sound from the diaphragm 27. With this configuration, it is possible to obtain a mini component system 14 that has a low environmental load that could not be realized in the past, and that enables high quality with high sound quality.

  In addition, although the audio | voice minicomponent system 14 was demonstrated as an application to the apparatus of the speaker 10, it is not limited to this. It can also be applied to portable audio devices that can be carried and charging systems. Furthermore, it can be widely applied and deployed in video equipment such as liquid crystal televisions and plasma display televisions, information communication equipment such as mobile phones, and electronic equipment such as computer-related equipment.

(Embodiment 4)
Hereinafter, the fourth aspect of the present invention will be described with reference to the fourth embodiment.

  FIG. 5 shows a cross-sectional view of an automobile 15 which is an apparatus according to an embodiment of the present invention.

  As shown in FIG. 5, an automobile 15 is configured by incorporating the speaker 10 of the present invention into a rear tray or a front panel and using it as a part of car navigation or car audio.

  By adopting this configuration, it becomes possible to achieve an excellent design with high sound quality while reducing the environmental load by utilizing the characteristics of the speaker 10, and reduce the environmental load of a device such as an automobile equipped with the speaker 10. be able to.

  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 that reduces environmental burden and requires high sound quality, and further to a device such as an automobile.

Sectional drawing of the diaphragm for speakers in one embodiment of this invention The top view of the diaphragm for speakers in one embodiment of the present 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 apparatus in one embodiment of this invention Sectional view of a conventional speaker diaphragm

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Speaker 11 Enclosure 12 Amplifier 13 Operation part 14 Mini component system 15 Car 21 Magnet 22 Upper plate 23 Yoke 24 Magnetic circuit 25 Magnetic gap 26 Frame 27 Diaphragm 27A Polylactic acid 27B bamboo charcoal 28 Voice coil 29 Edge extracted from a plant

Claims (9)

A speaker diaphragm constituted by polylactic acid extracted from a plant and bamboo charcoal , wherein the bamboo charcoal is carbonized at a high temperature . The speaker diaphragm according to claim 1, further comprising bamboo fiber. In fiber length of bamboo fiber 0.2mm or more and less than 3mm and claims 3 speaker diaphragm according. 4. The speaker diaphragm according to claim 3, wherein the bamboo fiber content is 5% by weight or more and 55% by weight or less. 3. The speaker diaphragm according to claim 2, further comprising bamboo fibers refined to a microfibril state having an average fiber diameter of 10 [mu] m or less. The speaker diaphragm according to claim 2, wherein a part or all of the bamboo fiber is replaced with bamboo powder. A magnetic circuit, a frame coupled to the magnetic circuit, a polylactic acid extracted from a plant, and bamboo charcoal, and a diaphragm coupled to the outer periphery of the frame, and coupled to the diaphragm A speaker comprising a voice coil, a part of which is disposed within a working range of magnetic flux generated from the magnetic circuit , wherein the bamboo charcoal is carbonized at a high temperature . A main body, a magnetic circuit, and a frame coupled to the magnetic circuit. The body is composed of polylactic acid extracted from a plant and bamboo charcoal, and is coupled to the diaphragm and the diaphragm coupled to the outer periphery of the frame. In addition, the bamboo charcoal is heated at a high temperature in an electronic device having a voice coil partly disposed within a working range of a magnetic flux generated from the magnetic circuit and a speaker fed from the main body. Carbonized electronic equipment. A frame that is coupled to a magnetic circuit, polylactic acid extracted from a plant, and bamboo charcoal, and a speaker diaphragm that is coupled to the outer periphery of the frame, and a part of the diaphragm that is coupled to the diaphragm Wherein the bamboo charcoal is carbonized at a high temperature . The apparatus comprises a speaker comprising a voice coil disposed in a magnetic gap of the magnetic circuit.

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