JP2009089303A - Speaker diaphragm, speaker using same, and electronic equipment and device using the speaker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a speaker diaphragm for use in audio equipment, a speaker, and electronic equipment and a device using the speaker, wherein the speaker diaphragm has a small environmental load and high sound quality. <P>SOLUTION: The speaker diaphragm is formed of a resin of a plant material, an olefin-based resin, and bamboo fiber to attain high heat resistance and strength and superior outward appearance and also to be friendly to environments. <P>COPYRIGHT: (C)2009,JPO&INPIT

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

  However, since the base resin polypropylene is a petroleum raw material, it has a large environmental impact.

  For this reason, in recent years, studies have been actively conducted on the use of polylactic acid, which is a plant material, as a resin in the movement of depetrochemicals.

As prior art document information relating to the invention of this application, for example, Patent Document 1 is known.
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 in terms of insufficient strength, low sound speed, and low internal loss.

  Further, the conventional polypropylene resin has a problem that the environmental load is large because the amount of carbon dioxide generated at the time of incineration is large.

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

  In order to achieve the above object, the present invention uses a resin obtained by alloying a plant raw material resin and a petroleum raw material olefin resin as a base resin, and further adds bamboo fiber for the purpose of controlling sound quality. It constitutes a diaphragm.

  With this configuration, it is possible to improve the heat resistance, which is a problem of polylactic acid, and to provide a loudspeaker diaphragm with high sound speed and large internal loss. Therefore, a speaker diaphragm with high sound quality can be achieved while reducing the environmental load compared to the conventional resin diaphragm.

  As described above, according to the present invention, a speaker diaphragm is formed of a plant raw material resin, an olefin resin, and bamboo fiber.

  With this configuration, it is possible to improve the heat resistance, which is a problem of polylactic acid, and to provide a loudspeaker diaphragm with high sound speed and large internal loss.

  Moreover, since the ratio of the plant raw material which occupies for a diaphragm material by this structure increases, a petroleum raw material reduces.

  Therefore, it can be said that the loudspeaker diaphragm composed of the plant raw material resin, the olefin resin and the bamboo fiber can reduce the environmental load compared to the conventional resin diaphragm.

  Therefore, the speaker diaphragm of the present invention can provide a high-quality speaker diaphragm with reduced environmental load.

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

(Embodiment 1)
Hereinafter, the first to eleventh aspects of the present invention will be described using 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 FIGS. 1 and 2, the diaphragm 1 uses a resin obtained by alloying a plant raw material resin and an olefin resin as a base resin. A material obtained by uniformly dispersing bamboo fibers 1D in a base resin 1C obtained by alloying polylactic acid 1A as a plant raw material resin and polypropylene 1B as an olefin-based resin is formed by injection molding.

  With this configuration, the heat resistance that has been a problem is improved. Also, by using polypropylene 1B as the olefin resin, the base resin 1C has a specific gravity smaller than that of polylactic acid 1A. Therefore, the weight can be reduced compared with the polylactic acid-based speaker diaphragm, which is important for acoustic performance. This leads to increased sound pressure, which is one of the major factors. Moreover, by using bamboo fiber 1D, in addition to the improvement in elastic modulus and internal loss, further weight reduction can be achieved. Moreover, the bamboo fiber 1D has a great deodorizing effect and has no odor peculiar to plant fibers, so that it can be used in a wide range of in-vehicle speakers and indoor audio.

  Moreover, not only the effect of adjusting the physical properties by using bamboo fiber for sound quality control, but also the plantiness increases, and the sound quality can be improved while reducing the environmental load. The plant degree here refers to the weight% of the material made of the plant raw material, and is the total weight% of the resin of the plant raw material and the plant fiber contained in the speaker diaphragm. The reason why the environmental load decreases as the degree of planting increases is that carbon dioxide generated at the time of incineration and disposal of the diaphragm means that carbon dioxide is newly generated in the case of petroleum raw materials. This is because a part of the carbon dioxide generated at the time of incineration disposal also includes carbon dioxide originally held by the plant, so that the net amount of carbon dioxide emission can be reduced.

  The fiber length of the bamboo fiber to be mixed is preferably 0.2 mm or more and 5 mm or less.

  By using bamboo fiber within this fiber length range, the effect when the base resin 1C and bamboo fiber 1D are combined 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. Further, if the fiber length of the bamboo fiber is longer than 5 mm, the appearance is 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 bamboo fiber length of 0.2 mm or more and 5 mm or less.

  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, it is more preferable that bamboo fiber further contains bamboo fiber refined | miniaturized to the microfibril state whose average fiber diameter is 10 micrometers or less.

  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.

  In general, the fiber has higher elasticity when the aspect ratio (L / D), which is the ratio between the fiber length L and the fiber diameter D, is larger, and the bamboo fiber that has been refined to the microfibril state has a larger aspect ratio, and therefore has 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 the following cases, injection molding can be easily performed.

  In addition, since the plantiness of the material is increased, it is possible to obtain a speaker diaphragm having high sound quality while reducing the environmental load. The plant degree here refers to the total weight percentage of plant raw material resin made from corn etc. and plant fiber such as bamboo fiber, and how to reduce the carbon dioxide emission which is a greenhouse gas without using petroleum raw material This is one measure of whether it can be reduced.

  Further, bamboo charcoal may be mixed. Bamboo charcoal here refers to a granular material obtained by cutting bamboo material to an appropriate size in advance and carbonizing it at a high temperature of about 800 ° C. Bamboo charcoal not only has the role of improving the elastic modulus, but also can achieve a high-quality appearance without using the carbon-based pigments used in conventional black-colored speaker diaphragms. Therefore, a high-performance and high-quality speaker diaphragm can be obtained by using bamboo charcoal.

  In addition, since bamboo charcoal is made from plant fiber, the plant content is increased, and high performance and high quality can be realized while further reducing the environmental burden.

  Further, a reinforcing material may be included. As the reinforcing material, natural minerals such as mica and talc can be used. Mica and talc are also effective as a nucleating agent for promoting crystallization of polylactic acid, can shorten the molding cycle of the diaphragm, and can improve heat resistance.

  Further, polylactic acid may be further mixed into the reinforcing material. Polylactic acid itself has a high elastic modulus and high fluidity. Since the degree of planting can be increased and the elastic modulus can be improved without reducing fluidity, a loudspeaker diaphragm with less environmental impact can be obtained.

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

(Example 1)
Polylactic acid content is 30% by weight, polypropylene content is 30% by weight, bamboo fiber content is 10% by weight, bamboo charcoal content is 5% by weight, and mica content is 25% by weight. Resin pellets were prepared by melting and kneading a material with a plant content of 45%, and injection molded at a molding temperature of 200 ° C. to obtain a speaker diaphragm having a 16 cm aperture.

(Comparative Example 1)
A loudspeaker diaphragm was obtained in the same manner as in Example 1 using only polylactic acid and having a plant degree of 100%.

(Comparative Example 2)
A loudspeaker diaphragm was obtained in the same manner as in Example 1 using a material having a plant content of 0% and comprising a composition having a polypropylene content of 75% by weight and a mica content of 25% by weight.

<Evaluation of the physical properties>
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. The 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.

  Further, the speaker diaphragm of Comparative Example 2 is a diaphragm containing 25% by weight of mica as a reinforcing material in polypropylene of a petroleum raw material resin, which is a conventional industrial product. Since the internal loss is improved and the degree of planting is large, the speaker diaphragm of the embodiment can be said to be a high-quality speaker diaphragm with reduced environmental load.

<Heat resistance evaluation>
With respect to Example 1, Comparative Example 1, and Comparative Example 2, they were left in a thermostatic bath for 240 hours in an atmosphere at a temperature of 100 ° C. to evaluate heat resistance.

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

  As described above, the present invention can improve the lack of heat resistance and strength, which are disadvantages of conventional polylactic acid, by constituting a speaker diaphragm from a plant raw material resin, an olefin resin and bamboo fiber. The sound velocity and internal loss are improved, and a loudspeaker diaphragm can be realized.

  Compared to resin diaphragms generally used in industrial products, the sound velocity and internal loss are improved, and the degree of vegetation is increased. Can be obtained.

(Embodiment 2)
The second aspect of the present invention will be described below with reference to 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 2 is sandwiched between an upper plate 3 and a yoke 4 to constitute 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 any one of the diaphragms 1 to 11 is bonded to the peripheral edge of the frame 7 via an edge 9. One end of the voice coil 8 is coupled to the center of the diaphragm 1 and the other end is coupled so as to fit into the magnetic gap 6 of the magnetic circuit 5.

  In the above, the speaker having the inner magnetic type magnetic circuit 5 has been described. However, the present invention is not limited to this and may be applied to a speaker having an outer magnetic type magnetic circuit.

  With this configuration, as described in Embodiment 1, a high-quality speaker with reduced environmental load can be realized.

(Embodiment 3)
The third aspect of the present invention will be described below 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 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 a mini component system 14 that has a low environmental load that could not be realized in the past, and that enables high quality and high 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 portable audio devices and game devices. 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)
The fourth embodiment of the present invention will be described below 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 taking advantage of the characteristics of the speaker 10 while reducing the environmental load, and also 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 are applied to an electronic device such as an audiovisual device or an information communication device that reduces environmental burden and requires a good sound production, and further to a device such as an automobile. it can.

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 Cross-sectional view of a conventional speaker

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Diaphragm 1A Polylactic acid 1B Polypropylene 1C Base resin 1D 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 Player 14 Mini component system 15 Car

Claims (14)

A loudspeaker diaphragm composed of a plant material resin, an olefin resin and bamboo fiber. The speaker diaphragm according to claim 1, wherein the plant raw material resin is polylactic acid. The speaker diaphragm according to claim 1, wherein the olefin resin is polypropylene. The diaphragm for a speaker according to claim 2, wherein the fiber length of the bamboo fiber is 0.2 mm or more and 5 mm or less. The speaker diaphragm according to claim 1, wherein the bamboo fiber content is 5 wt% or more and 55 wt% or less. The speaker diaphragm according to claim 1, further comprising bamboo fibers refined to a microfibril state having an average fiber diameter of 10 μm or less. The speaker diaphragm according to claim 1, wherein the bamboo fiber is bamboo powder. The speaker diaphragm according to claim 1, further comprising bamboo charcoal. The speaker diaphragm according to claim 1, further comprising a reinforcing material. The loudspeaker diaphragm according to claim 9, wherein the reinforcing material is natural mineral such as talc or mica. The speaker diaphragm according to claim 9, wherein the reinforcing material is polylactic acid. A magnetic circuit, a frame coupled to the magnetic circuit, a plant raw material resin, an olefin resin and bamboo fiber, and a diaphragm coupled to the outer periphery of the frame, and coupled to the diaphragm And a voice coil, a part of which is disposed within a range of action of magnetic flux generated from the magnetic circuit. An electronic device comprising the speaker according to claim 12. An apparatus comprising the speaker according to claim 12 as a moving means.

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