JP2009089302A - Speaker diaphragm, speaker using the same, and electronic device and apparatus using the speaker - Google Patents

Abstract

The present invention relates to a loudspeaker diaphragm, a loudspeaker, an electronic device and an apparatus used for an acoustic device, and an object thereof is to provide a loudspeaker loudspeaker having a low environmental load. .
In order to achieve this object, the present invention comprises a speaker diaphragm made of a plant raw material resin, a natural mineral and a plant fiber, so that the heat resistance and strength are high, and the appearance is excellent. It is configured to be able to realize a high-quality speaker diaphragm with little environmental load.
[Selection] Figure 1

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 derived from petroleum, it has a large environmental impact.

  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.

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 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 constitutes a speaker diaphragm from a plant raw material resin, a natural mineral and a plant fiber.

  With this configuration, natural minerals and plant fibers have an effect of promoting crystallization of polylactic acid and improving heat resistance, which is a problem. Further, not only the crystallization is promoted but also the sound velocity of the speaker diaphragm is increased to improve the elastic modulus. Plant fibers also have the effect of improving internal losses.

  Therefore, the speaker diaphragm has high sound quality and low environmental load.

  As described above, according to the present invention, a speaker diaphragm is constituted by a plant raw material resin, a natural mineral, and a plant fiber.

  With this configuration, it is possible to improve heat resistance by promoting crystallization, which is a problem of polylactic acid.

  Further, both natural minerals and plant fibers have an effect of improving the elastic modulus, and plant fibers have an effect of improving internal loss, so that distortion and resonance can be suppressed.

  Therefore, the speaker diaphragm composed of plant raw material resin, natural mineral and plant fiber can be a high-quality speaker diaphragm having a smaller environmental load than conventional resin diaphragms.

  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 FIG. 1 and FIG. 2, the diaphragm 1 uses a plant raw material resin as a base resin, and polylactic acid 1A having a high bending elastic modulus is preferable for the selection of the resin. Natural minerals and plant fibers are uniformly dispersed in this polylactic acid 1A. Here, 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 this polylactic acid 1A.

  With this configuration, the mica 1B and the bamboo fiber 1C can accelerate the crystallization of the polylactic acid 1A, shorten the injection molding cycle, and improve the heat resistance that has been a problem. Moreover, since the bamboo fiber 1C is hard and has flexibility, it has the effect of improving the elastic modulus and the effect of improving the internal loss.

  As a result, a speaker diaphragm having a high elastic modulus and a high internal loss is obtained, and a speaker using the diaphragm has a higher sound quality.

  Moreover, bamboo has a great deodorizing effect and has no odor peculiar to plant fibers, so it can be used in a wide range of in-vehicle speakers and indoor audio.

  In addition, bamboo fiber not only has the effect of adjusting physical properties to improve sound quality, but also increases plantiness and can improve sound quality while reducing environmental impact. 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.

  Therefore, the speaker diaphragm composed of polylactic acid, mica, and bamboo fiber is environmentally friendly and can realize better sound quality.

  Moreover, the fiber length of the bamboo fiber to mix is 0.2 mm or more, and 5 mm or less is desirable. 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. 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, it is difficult to obtain a diaphragm having a surface thickness of 0.3 mm or less by injection molding because the resin has low fluidity.

  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 a microfibril state increases the entanglement of bamboo fibers, thereby improving the strength. 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.

  Moreover, 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.

  And since the plant degree of material becomes large, the diaphragm for speakers with a smaller environmental load can be obtained. The plant degree here refers to the total weight of plant raw material resin made from corn etc. and plant fiber such as bamboo fiber, and how to reduce the emission of carbon dioxide, which is a greenhouse gas, without using petroleum-derived materials It is a measure of whether it can be done.

  Further, the elastic modulus can be further improved by further adding a carbonized material. In particular, when bamboo charcoal is used, the elastic modulus can be increased without lowering the plant degree.

  In addition, bamboo charcoal usually serves as a carbon pigment used in black speaker diaphragms, and can not only improve sound quality but also have a high-quality appearance.

  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.

  Further, a conventional petroleum resin may be further included. Polypropylene is particularly preferable for petroleum resins. Polypropylene itself has a large internal loss and a low specific gravity. Therefore, the weight of the diaphragm can be reduced and the internal loss can be increased.

  An example of the subclaims of the present invention will be described below, but this example does not limit the scope of the present invention.

(Example 1)
A resin pellet was prepared by melt-kneading with a composition of 25% by weight of polylactic acid, 15% by weight of mica, 15% by weight of bamboo fiber, and 45% by weight of polypropylene, Injection molding was performed at a molding temperature of 200 ° C. to obtain a speaker diaphragm having a 16 cm aperture.

(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 85% by weight and a mica content of 15% 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 the table, it is clear that the sound diaphragm and the internal loss of the speaker diaphragm of Example 1 are improved as compared with the speaker diaphragm of Comparative Example 1.

  Further, the speaker diaphragm of Comparative Example 2 is a diaphragm containing 15% by weight of mica as a reinforcing material in polypropylene of petroleum-derived resin, which is a conventional industrial product. Internal loss has improved.

<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 the disadvantages of conventional polylactic acid, by constituting the speaker diaphragm from plant raw material resin, natural mineral and plant fiber, Improve sound speed and internal loss. Moreover, since the diaphragm is made of not only the sound quality improvement but also a material having a higher plant level than the conventional one, it is possible to obtain a loudspeaker diaphragm with less environmental load.

(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, it is possible to realize a high-quality speaker with low environmental load.

(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 making the best use of the characteristics of the speaker 10 and reducing the environmental load, and also reduce the environmental load of devices such as automobiles 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 and an information communication device that requires a high sound quality speaker 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 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 part 14 Mini component system 15 Car

Claims (16)

A loudspeaker diaphragm composed of plant-based resin, natural minerals, and plant fibers. The speaker diaphragm according to claim 1, wherein the plant raw material resin is polylactic acid. 2. The speaker diaphragm according to claim 1, wherein the natural mineral is either mica or talc, or both. The speaker diaphragm according to claim 1, wherein the plant fiber is bamboo fiber. The speaker diaphragm according to claim 4, 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 4, wherein the bamboo fiber content is 5 wt% or more and 55 wt% or less. The speaker diaphragm according to claim 4, 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 4, wherein the bamboo fiber is bamboo powder. The speaker diaphragm according to claim 1, further comprising a carbonized material. The speaker diaphragm according to claim 9, wherein the carbonized material is bamboo charcoal. The loudspeaker diaphragm according to claim 1, further comprising a petroleum raw material resin. 12. The loudspeaker diaphragm according to claim 11, wherein a resin of petroleum raw material is a thermoplastic resin. The diaphragm for a speaker according to claim 12, wherein the thermoplastic resin is polypropylene. A magnetic circuit, a frame coupled to the magnetic circuit, a plant raw material resin, a natural mineral and a plant fiber, 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 range of action of magnetic flux generated from the magnetic circuit. An electronic device comprising the speaker according to claim 14. An apparatus comprising the speaker according to claim 14 as a moving means.

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