U.S. patent application number 13/352407 was filed with the patent office on 2012-05-10 for diaphragm for speaker, frame for speaker, dust cap for speaker, speaker and apparatus using them, and method for manufacturing component for speaker.
This patent application is currently assigned to Panasonic Corporation. Invention is credited to Yoshimichi KAJIHARA, Kazuyoshi Mimura, Shinya Mizone, Kazuaki Nishimura, Takashi Sabato.
Application Number | 20120112382 13/352407 |
Document ID | / |
Family ID | 39608539 |
Filed Date | 2012-05-10 |
United States Patent
Application |
20120112382 |
Kind Code |
A1 |
KAJIHARA; Yoshimichi ; et
al. |
May 10, 2012 |
DIAPHRAGM FOR SPEAKER, FRAME FOR SPEAKER, DUST CAP FOR SPEAKER,
SPEAKER AND APPARATUS USING THEM, AND METHOD FOR MANUFACTURING
COMPONENT FOR SPEAKER
Abstract
A speaker diaphragm is configured by a compound mixed with resin
and bamboo fiber. The diaphragm satisfying the advantage of the
bamboo fiber of high sound quality and a large degree of freedom in
the setting of the characteristic value of the diaphragm and the
advantage of the diaphragm made of a resin with improved humidity
resistance reliability and strength, excellent external appearance,
and enhanced productivity and dimension stability is obtained.
Inventors: |
KAJIHARA; Yoshimichi;
(Osaka, JP) ; Mizone; Shinya; (Mie, JP) ;
Mimura; Kazuyoshi; (Mie, JP) ; Sabato; Takashi;
(Mie, JP) ; Nishimura; Kazuaki; (Mie, JP) |
Assignee: |
Panasonic Corporation
Osaka
JP
|
Family ID: |
39608539 |
Appl. No.: |
13/352407 |
Filed: |
January 18, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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12515622 |
May 20, 2009 |
8122996 |
|
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PCT/JP2007/074497 |
Dec 20, 2007 |
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13352407 |
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Current U.S.
Class: |
264/241 |
Current CPC
Class: |
H04R 7/12 20130101; H04R
31/003 20130101; H04R 2231/001 20130101; H04R 2307/021 20130101;
H04R 2307/029 20130101; H04R 2307/025 20130101 |
Class at
Publication: |
264/241 |
International
Class: |
B29C 45/46 20060101
B29C045/46 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 22, 2006 |
JP |
JP 2006-345487 |
Dec 22, 2006 |
JP |
JP 2006-345488 |
Dec 26, 2006 |
JP |
JP 2006-349171 |
Feb 6, 2007 |
JP |
JP 2007-026728 |
Claims
1. A method for manufacturing a speaker component comprising: a
miniaturization step of partially miniaturizing a fiber to a
microfibrillated state to generate a microfibrillated fiber
containing moisture; a compounding step of substituting the
moisture contained in the microfibrillated fiber and a granulated
resin to generate a compound containing the microfibrillated fiber
and the resin; and a molding step of injection molding the
compound.
2. The method for manufacturing the speaker component according to
claim 1, wherein in the miniaturization step, the moisture is
adjusted such that the fiber has a concentration of greater than or
equal to 0.5% by weight and smaller than or equal to 1.5% by
weight.
3. The method for manufacturing the speaker component according to
claim 1, wherein the compounding step includes a substituting step
of substituting the moisture and the resin by heating and
drying.
4. The method for manufacturing the speaker component according to
claim 1, further comprising: a pelletization step of pelletizing
the compound provided before the molding step.
5. The method for manufacturing the speaker component according to
claim 1, wherein the fiber is a natural fiber.
6. The method for manufacturing the speaker component according to
claim 5, wherein the natural fiber is a bamboo fiber.
7. The method for manufacturing the speaker component according to
claim 6, wherein the bamboo fiber is a bamboo pulp.
8. The method for manufacturing the speaker component according to
claim 1, wherein the fiber is a chemical fiber.
9. The method for manufacturing the speaker component according to
claim 8, wherein the chemical fiber is an aramid fiber.
10. The method for manufacturing the speaker component according to
claim 9, wherein the aramid fiber is an aramid pulp.
11. The method for manufacturing the speaker component according to
claim 1, wherein a fiber length of the microfibrillated fiber is
greater than or equal to 0.2 mm and smaller than or equal to 3
mm.
12. The method for manufacturing the speaker component according to
claim 1, wherein the resin is a polypropylene.
13. The method for manufacturing the speaker component according to
claim 1, further comprising: a mixing step of mixing a reinforcing
material, a dilution resin, a fluidity modifier, a compatibilizing
agent or a coloring agent to the compound.
Description
[0001] This application is a continuation of U.S. patent
application Ser. No. 12/515,622, filed May 20, 2009, which is a
U.S. National Phase Application of PCT International Application
PCT/JP2007/074497, filed Dec. 20, 2007, the entire disclosures of
which are incorporated herein by reference.
TECHNICAL FIELD
[0002] The present invention relates to a speaker diaphragm, a
speaker frame, and a speaker dust cap used in various acoustic
equipments or in video equipments; a speaker, a stereo system, or a
television set as well as a device such as a moving body using the
same; and a method for manufacturing a speaker component.
BACKGROUND ART
[0003] A speaker of the related art will be described below with
reference to FIG. 14. FIG. 14 is a cross-sectional view of a
speaker of the related art.
[0004] As shown in FIG. 14, speaker 110 includes speaker diaphragm
101 (hereinafter referred to as diaphragm 101), magnetic circuit
105, speaker frame 107 (hereinafter referred to as frame 107), and
voice coil 108. Magnetic circuit 105 is configured by sandwiching
polarized magnet 102 between upper plate 103 and yoke 104. Frame
107 is coupled to yoke 104. An outer periphery of diaphragm 101 is
coupled to an outer peripheral portion of frame 107 by way of edge
109. One end of voice coil 108 is coupled to a central portion of
diaphragm 101. The other end of voice coil 108 is arranged to fit
into magnetic gap 106 formed by magnetic circuit 105. Speaker dust
cap 111 (hereinafter referred to as cap 111) is coupled to a front
surface portion of diaphragm 101. Voice coil 108 includes tubular
voice coil body 108a, and has a structure in which coil 108b is
wounded around an outer peripheral portion of voice coil body 108a.
An inner periphery of damper 112 is coupled to voice coil 108, and
an outer periphery of damper 112 is coupled to frame 107. Speaker
110 is configured in such manner.
[0005] Diaphragm 101 is made of resin such as polypropylene
(hereinafter referred to as PP), and is formed by injection molding
a thermally fused resin pellet into a molding die set with a shape
of diaphragm 101. A single material such as PP is generally used
for the type of a resin material used in injection molding.
[0006] Blend-type diaphragm 101 using different types of resin also
exists for the purpose of adjusting characteristic value for
diaphragm 101, that is, adjusting characteristics or sound quality
for speaker 110. Furthermore, in adjusting the characteristic value
where adjustment is difficult only with a resin, adjustment of the
characteristic value of diaphragm 101 and adjustment of the
characteristics for speaker 110 or sound quality are carried out by
mixing a reinforcing material such as mica. Moreover, in order to
increase a degree of freedom in adjusting the characteristic value,
the sound quality adjustment of diaphragm 101 is carried out by
mixing a pulp material. Such speaker 110 of the related art is
disclosed in, for example, patent document 1 and patent document
2.
[0007] The single material such as PP is also generally used for
cap 111 used in speaker 110, similar to diaphragm 101. Speaker 110
of the related art using cap 111 is disclosed in, for example,
patent document 3.
[0008] Such diaphragm 101 of the related art uses a manufacturing
method by papermaking, or a manufacturing method by injection
molding or pressing of a resin. Thus, diaphragm 101 of the related
art is made of paper or is made of a resin.
[0009] Therefore, diaphragm 101 uses different materials depending
on the application while exploiting the features of each material.
However, each has problems, and it is difficult to satisfy the
market demand such as lower distortion, wider band, and higher
dynamic range. Furthermore, in the production of diaphragm 101 made
of paper, lowering the cost of the component is difficult as great
number of steps of papermaking is required. In diaphragm 101 made
of a resin, on the other hand, only the standardized characteristic
value specific to the resin or the material can be obtained. Thus,
the adjustment range of the characteristics and the sound quality
for speaker 110 is very narrow.
[0010] Diaphragm 101 in which the resin and the pulp material are
mixed has a large degree of freedom in the sound quality
adjustment, and moisture resistance reliability is also improved.
However, diaphragm 101 of the related art has a problem in that the
strength is insufficient to enhance the sound quality.
[0011] Cap 111 used in speaker 110 also is made of the material and
the manufacturing method of cap 111 is similar to diaphragm 101.
Therefore, cap 111 has the same problems as diaphragm 101 of the
related art.
[0012] Frame 107 is desired to have high rigidity, a damping
effect, and high internal loss so that the vibration of diaphragm
101 does not transmit to magnetic circuit 105 or resonance is less
likely to occur. Frame 107 of the related art thus mainly is made
of an iron plate, a material of an aluminum die-cast, or a
resin.
[0013] However, frame 107 made of the iron plate has problems in
that magnetic leakage is large, and the external appearance also
lacks in sophisticated image. Frame 107 made of the material of
aluminum die-cast excels in magnetic leakage and external
appearance quality, and has high rigidity. However, frame 107 made
of the material of aluminum die-cast has a problem in that it is
very expensive. In order to solve such problems, a thermoplastic
synthetic resin is often being injection molded to be molded to the
shape of frame 107 and used in recent years. In particular, frame
107 made of the resin has a large degree of freedom in a shape, and
is suited for a lighter weight. Speaker 110 using such frame 107 is
disclosed in, for example, patent document 4.
[0014] However, such frame 107 made of the resin of the related art
may be light weight, but does not have enough rigidity with only
the resin of a base material. Thus, an inorganic filler such as a
glass fiber or mica is often added. In particular, from the aspects
of lighter weight, moldability, acoustic performance, and the like,
PP having a small specific gravity and large internal loss is used
for the resin of frame 107. The addition of the inorganic filler of
greater than or equal to 30% by weight is required to satisfy the
acoustic performance of frame 107. The rigidity of frame 107
becomes higher by adding the inorganic filler. However, the
specific gravity of frame 107 also increases, and thus the weight
of frame 107 becomes heavy. Moreover, a problem in that the effect
of absorbing unnecessary vibration reduces arises since the
internal loss of frame 107 becomes small.
[0015] A method for manufacturing diaphragm 101 of the related art
will now be described with reference to FIG. 15. FIG. 15 is a
process chart showing the method of manufacturing speaker diaphragm
101 made of a resin using injection molding of the related art.
[0016] As shown in FIG. 15, resin 114 such as PP is dry blended
with PP 115 with a reinforcing material such as mica to produce
master batch 116. Master batch 116 is then pelletized to produce
master batch pellet 117 (hereinafter referred to as pellet 117).
Pellet 117 is then injected in an injection molding machine to
thereby manufacturing a speaker component such as diaphragm
101.
[0017] In the injection molding machine, injected pellet 117 is
heated and melted through a heating step. It is then injected into
molding die 118 for diaphragm 101 using an extruder. The injected
PP resin is cooled and solidified, and then taken out from the
molding die 108, thereby forming diaphragm 101. Diaphragm 101 made
of a resin typified by PP and the like is manufactured using such
an injection molding step.
[0018] A single material such as PP is generally used for the type
of resin material used in injection molding. In addition to the PP,
blend-type diaphragm 101 in which different types of resins are
mixed also exists for the purpose of adjusting a characteristic
value for diaphragm 101, that is, adjusting characteristics and
sound quality for speaker 110.
[0019] A method for manufacturing blend-type diaphragm 101 includes
grinding a plurality of types of resin pellets to be mixed using a
grinder, where a blending ratio is set. Mixing is performed by dry
blending, which is then used to manufacture diaphragm 101.
[0020] Such a method for manufacturing speaker 110 of related art
is disclosed in, for example, patent document 5.
[0021] In order to respond to the market demand on the speaker
component such as diaphragm 101, in particular, from the
standpoints of quality stabilization and water resistance
reliability, and furthermore, diversification of design, diaphragm
101 made of a resin is very popular.
[0022] However, in the method for manufacturing the speaker
component such as diaphragm 101 of the related art, diaphragm 101
made of a resin has a problem in that adjustment of the
characteristics and the sound quality for speaker 110 can only be
carried out within a range of the characteristic value of the
material of the resin being used, and only a standardized sound can
be generated. [0023] [Patent document 1] Unexamined Japanese Patent
Publication No. S59-176995 [0024] [Patent document 2] Unexamined
Japanese Patent Publication No. 2005-236497 [0025] [Patent document
3] Unexamined Japanese Patent Publication No. H03-289298 [0026]
[Patent document 4] Unexamined Japanese Patent Publication No.
2003-37891 [0027] [Patent document 5] Unexamined Japanese Patent
Publication No. H01-248900
DISCLOSURE OF THE INVENTION
[0028] The speaker diaphragm of the present invention is resolved
with lack of strength, and provides a speaker in which the
adjustment range of the characteristics and the sound quality of
the speaker is wide when used in the speaker.
[0029] The speaker diaphragm of the present invention includes a
resin and a cellulose fiber, where the cellulose fiber is a bamboo
fiber. According to such configuration, the speaker diaphragm of
high productivity having high strength and high elastic modulus is
obtained.
[0030] The speaker frame of the present invention is resolved with
lack of strength, and provides a speaker having a wide adjustment
range of speaker characteristics and sound quality when used in
speakers.
[0031] The speaker frame of the present invention includes a resin
and a cellulose fiber, where the cellulose fiber is a bamboo fiber.
According to such configuration, the speaker frame of high
productivity having high strength and high elastic modulus is
obtained.
[0032] The speaker dust cap of the present invention is resolved
with lack of strength, and provides a speaker having a wide
adjustment range of speaker characteristics and sound quality when
used in speakers.
[0033] The speaker dust cap of the present invention includes a
resin and a cellulose fiber, where the cellulose fiber is a bamboo
fiber. According to such configuration, the speaker dust cap of
high productivity having high strength and a high elastic modulus
is obtained.
[0034] A method for manufacturing a speaker component of the
present invention includes a miniaturization step, a compounding
step, and a molding step, and in the miniaturization step, the
fiber is partially miniaturized to the microfibrillated state to
generate a microfibrillated fiber containing moisture; in the
compounding step, the moisture contained in the microfibrillated
fiber and the granulated resin are substituted to generate a
compound containing the microfibrillated fiber and the resin; and
in the molding step, the compound is injection-molded. According to
such manufacturing method, the secondary aggregation of the resin
and the fiber is prevented, and the speaker component with enhanced
dispersibility is obtained. Furthermore, a speaker with excellent
external appearance in which the degree of freedom in the
adjustment of sound quality is large, and the humidity resistance
and water resistance reliabilities are improved is provided by
using the obtained speaker component.
BRIEF DESCRIPTION OF THE DRAWINGS
[0035] FIG. 1 is a cross-sectional view of a speaker according to
Embodiment 1 of the present invention.
[0036] FIG. 2 is a cross-sectional view of a speaker diaphragm used
in the speaker shown in FIG. 1
[0037] FIG. 3 is a plan view of the speaker diaphragm shown in FIG.
2.
[0038] FIG. 4A is a partially detailed cross-sectional view of the
speaker diaphragm shown in FIG. 2.
[0039] FIG. 4B is a partially detailed cross-sectional view of a
speaker diaphragm of another mode used in the speaker shown in FIG.
1.
[0040] FIG. 4C is a partially detailed cross-sectional view of a
speaker diaphragm of another furthermore mode used in the speaker
shown in FIG. 1.
[0041] FIG. 5 is a cross-sectional view of a speaker according to
Embodiment 2 of the present invention.
[0042] FIG. 6 is a cross-sectional view of a speaker frame used in
the speaker shown in FIG. 5.
[0043] FIG. 7 is a partially detailed cross sectional view of the
speaker frame shown in FIG. 6.
[0044] FIG. 8 is a cross-sectional view of a speaker according to
Embodiment 3 of the present invention.
[0045] FIG. 9 is a cross-sectional view of a speaker dust cap used
in the speaker shown in FIG. 8.
[0046] FIG. 10 is a partially detailed cross sectional view of the
speaker dust cap shown in FIG. 9.
[0047] FIG. 11 is an external appearance view of a device according
to Embodiment 4 of the present invention.
[0048] FIG. 12 is a cross-sectional view of a device according to
Embodiment 5 of the present invention.
[0049] FIG. 13 is a process chart showing a method for
manufacturing a speaker component according to Embodiment 6 of the
present invention.
[0050] FIG. 14 is a cross-sectional view of a speaker of the
related art.
[0051] FIG. 15 is a process chart showing a method for
manufacturing a speaker component of the related art.
REFERENCE MARKS IN THE DRAWINGS
[0052] 1, 1a is speaker diaphragm [0053] 2 magnet [0054] 3 upper
plate [0055] 4 yoke [0056] 5 magnetic circuit [0057] 6 magnetic gap
[0058] 7, 7a speaker frame [0059] 8 voice coil [0060] 8a voice coil
body [0061] 8b coil [0062] 9 edge [0063] 10, 10a, 10b speaker
[0064] 11, 11a speaker dust cap [0065] 15 compound [0066] 16 resin
[0067] 17 bamboo fiber [0068] 18 microfibrillated bamboo fiber
[0069] 19 bamboo powder [0070] 20 bamboo charcoal [0071] 21 speaker
system [0072] 22 enclosure [0073] 23 amplifier [0074] 24 amplifier
circuit [0075] 25 operation unit [0076] 26 mini-component system
[0077] 27 main body [0078] 50 automobile [0079] 51 rear tray [0080]
52 front panel [0081] 53 drive unit [0082] 54 steering [0083] 55
body [0084] 56 front wheel [0085] 57 rear wheel [0086] 58 seat
[0087] 59 machine room [0088] 61 polypropylene pellet [0089] 62
granulated polypropylene resin [0090] 63 fiber [0091] 64
microfibrillated fiber [0092] 65 compatibilizing agent [0093] 67
microfibrillated fiber compound pellet [0094] 68 reinforcing
material [0095] 69 dilution resin [0096] 70 fluidity modifier
[0097] 71 coloring agent [0098] 72 molding die
PREFERRED EMBODIMENTS FOR CARRYING OUT OF THE INVENTION
[0099] Embodiments of the present invention will be hereinafter
described using the drawings.
Embodiment 1
[0100] Embodiment 1 of the present invention will be described with
reference to FIG. 1 to FIG. 4. FIG. 1 is a cross-sectional view of
speaker 10 according to Embodiment 1 of the present invention. FIG.
2 is a cross-sectional view of speaker diaphragm 1 (hereinafter
referred to as diaphragm 1) used in speaker 10 shown in FIG. 1.
FIG. 3 is a plan view of diaphragm 1 shown in FIG. 2. FIG. 4A is a
partially detailed cross-sectional view of diaphragm 1 shown in
FIG. 2. FIG. 4B is a partially detailed cross sectional view of
speaker diaphragm 1 of another aspect used in speaker 10 shown in
FIG. 1.
[0101] As shown in FIG. 1, speaker 10 includes diaphragm 1,
magnetic circuit 5, speaker frame 7a (hereinafter referred to as
frame 7a), and voice coil 8. Magnetic circuit 5 is configured by
sandwiching polarized magnet 2 between upper plate 3 and yoke 4.
Frame 7a is coupled to yoke 4. An outer periphery of diaphragm 1 is
coupled to an outer peripheral portion of frame 7a by way of edge
9. One end of voice coil 8 is coupled to a central portion of
diaphragm 1. Another end of voice coil 8 is arranged to fit into
magnetic gap 6 formed by magnetic circuit 5. Speaker dust cap 11a
(hereinafter referred to as cap 11a) is coupled to a front surface
portion of diaphragm 1. Voice coil 8 includes tubular voice coil
body 8a, and has a structure in which coil 8b is wounded around an
outer peripheral portion of voice coil body 8a. An inner periphery
of damper 12 is coupled to voice coil 8, and an outer periphery of
damper 12 is coupled to frame 7a. Speaker 10 is configured in this
manner.
[0102] As shown in FIG. 4A, diaphragm 1 is formed from compound 15
in which resin 16 and bamboo fiber 17, which is a cellulose fiber,
are mixed. Diaphragm 1 is preferably formed by injection molding
compound 15. Bamboo fiber 17 partially includes microfibrillated
bamboo fiber 18 (hereinafter referred to as fiber 18) formed by
miniaturizing bamboo fiber 17 to a microfibrillated state. In other
words, compound 15 includes resin 16, bamboo fiber 17, and fiber
18.
[0103] Diaphragm 1 is formed by mixing bamboo fiber 17 to resin 16,
whereby the mechanical rigidity enhances. The rigidity of diaphragm
1 further enhances by including fiber 18. As diaphragm 1 includes
bamboo fiber 17 or fiber 18, speaker 10 having lighter weight and
larger internal loss is realized as compared to when an inorganic
filler is included.
[0104] Resin 16 preferably uses a crystalline or non-crystalline
olefin resin. Satisfactory moldability of diaphragm 1 is realized
by using the olefin resin for resin 16. The crystalline resin
and/or the non-crystalline resin are used depending on the
application of resin 16. Thus, resin 16 satisfies an optimum
characteristic value for a resin material.
[0105] Polypropylene (hereinafter referred to as PP) is used for
resin 16. The PP is generally easily available, and is easily
injection molded. Furthermore, diaphragm 1 having large internal
loss is obtained by using PP for resin 16. However, a material
selected for resin 16 is not limited to PP. The material selected
for resin 16 may be appropriately selected such that a desired
characteristic value for diaphragm 1 is obtained.
[0106] An engineering plastic may be used for resin 16, not limited
to PP. Diaphragm 1 excellent in heat resistance or solvent
resistance is obtained by using the engineering plastic for resin
16. Examples of the engineering plastic used in resin 16 include
polyacetal (POM: polyoxymethylene), polyamide (PA), polycarbonate
(PC) and polybutyleneterephthalate (PBT).
[0107] In view of environmental consideration, resin 16 may use a
biodegradable plastic typified by polylactic acid (PLA).
Environment-friendly diaphragm 1 of high performance that does not
require a special disposal method and that avoids extra discharge
of carbon dioxide in disposal is obtained by using a biodegradable
plastic for resin 16. Other than polylactic acid, the biodegradable
plastic may be polycaprolactam, a modified polyvinyl alcohol
(modified PVA), casein plastics, and the like. The polylactic acid
excels in transparency and rigidity as compared to other
biodegradable plastics. The polylactic acid also has satisfactory
compatibility with the cellulose of bamboo fiber 17, and thus
easily fixes on the surface of bamboo fiber 17. Thus,
environment-friendly diaphragm 1 of high rigidity in which the
external appearance color of bamboo fiber 17 is not affected is
obtained by using polylactic acid for resin 16.
[0108] Bamboo fiber 17 used in diaphragm 1 is not particularly
limited as long as it is a plant of the bamboo family. Bamboo fiber
17 is preferably a bamboo grown to a bamboo age of one or older,
excluding bamboo sprout of less than a bamboo age of one year or
child bamboo. The enhancement in rigidity and the enhancement in
toughness of diaphragm 1 are ensured by using the bamboo having a
bamboo age of one or older for bamboo fiber 17. Bamboo fiber 17
mixed in resin 16 is preferably a bamboo having a bamboo age of
four years or older and seven years or younger as the physicality
also stabilizes.
[0109] Diaphragm 1 that reproduces natural and light tone is
obtained by using bamboo fiber 17 in diaphragm 1. Thus, a dark and
standardized tone is suppressed as compared to a speaker diaphragm
formed only with resin 16. Furthermore, diaphragm 1 having a high
elastic modulus as compared to a speaker diaphragm including other
pulp material is obtained. Thus, the degree of freedom for
adjusting the characteristics of diaphragm 1 increases.
[0110] The entanglement between bamboo fibers 17 becomes stronger
by mixing microfibrillated bamboo fiber 18 miniaturized to the
microfibrillated state in diaphragm 1. As a result, diaphragm 1
having large strength and elastic modulus is obtained. The degree
of freedom in adjusting the sound quality for the speaker diaphragm
also increases.
[0111] The fiber length of fiber 18 mixed in diaphragm 1 is
preferably greater than or equal to 0.2 mm and smaller than or
equal to 3 mm. The effect of heating granulation when obtaining
compound 15 mixed with resin 16 and bamboo fiber 17 is efficiently
produced by including fiber 18 having a fiber length in a range of
greater than or equal to 0.2 mm and smaller than or equal to 3 mm
for diaphragm 1. The productivity and the quality of diaphragm 1
also enhance.
[0112] If the fiber length of fiber 18 is shorter than 0.2 mm, the
effect of fiber 18 is not efficiently produced, and diaphragm 1
having high elastic modulus is hardly obtained. If, on the other
hand, the fiber length of fiber 18 is longer than 3 mm, secondary
aggregation that occurs from the entanglement between fibers 18
easily occur, and dispersion failure of fiber 18 easily occurs.
Thus, a long time is required for the kneading of resin 16 and
bamboo fiber 17. An aggregate of fiber 18 may appear on the surface
of diaphragm 1, thereby affecting the external appearance of
speaker 10. Therefore, the productivity and the quality of
diaphragm 1 enhance if the fiber length of fiber 18 to be mixed in
diaphragm 1 is within a range of greater than or equal to 0.2 mm
and smaller than or equal to 3 mm.
[0113] The average fiber diameter of fiber 18 to be mixed in
diaphragm 1 is preferably smaller than or equal to 10 .mu.m. A
typical fiber has higher elasticity the larger the aspect ratio
(fiber length/fiber diameter=L/D), which is the ratio of the fiber
length L and the fiber diameter D. Therefore, microfibrillated
bamboo fiber 18 miniaturized to the microfibrillated state having a
relatively large aspect ratio, and high elastic modulus can be
expected. The entanglement between the fibers is not strong if the
average fiber diameter of fiber 18 is greater than 10 .mu.m.
Furthermore, the bonding between resin 16 and bamboo fiber 17, or
between bamboo fiber 17 and bamboo fiber 17 becomes strong if fiber
18 partially exists at a part of bamboo fiber 17. Therefore, the
synergistic effect of a higher elastic modulus of a single body of
bamboo fiber 17 and enhanced bonding strength between the fibers is
obtained if the average fiber diameter of fiber 18 to be mixed in
diaphragm 1 is smaller than to equal to 10 .mu.m, and diaphragm 1
having a higher elastic modulus is obtained.
[0114] If bamboo fiber 17 is contained in compound 15 in a great
amount, bamboo powder 19 may be used for a part of or all of bamboo
fiber 17 to expect a more natural and lighter tone. As shown in
FIG. 4B, the lowering of fluidity when forming diaphragm 1 through
injection molding is suppressed by using bamboo powder 19 in
diaphragm 1. The moldability of diaphragm 1 thereby improves. The
shape of bamboo powder 19 may not be a fibrous shape having an
aspect ratio, and is preferably a granulated shape obtained by
grinding bamboo fiber 17.
[0115] As shown in FIG. 4C, bamboo powder 19 having a granulated
shape is more preferably bamboo charcoal 20, which is obtained by
carbonizing bamboo powder 19. Bamboo charcoal 20 generated by
carbonizing bamboo powder 19 at a temperature of higher than or
equal to 600.degree. C. is preferably used in diaphragm 1.
Diaphragm 1 then has characteristics of higher elastic modulus and
higher internal loss. If diaphragm 1 is colored by adding a pigment
to diaphragm 1, the elastic modulus of diaphragm 1 tends to lower.
However, by mixing bamboo charcoal 20 in diaphragm 1, diaphragm 1
is colored and furthermore elastic modulus of diaphragm 1 is
enhanced. As a result, diaphragm 1 mixed with bamboo charcoal 20
has a high quality external appearance. Since the raw material of
bamboo charcoal 20 is bamboo as opposed to a typical coloring agent
such as a pigment, diaphragm 1 can reproduce a natural and light
sound.
[0116] The mixing ratio of bamboo fiber 17 with respect to resin 16
used in diaphragm 1 is preferably greater than or equal to 5% by
weight and smaller than or equal to 60% by weight. If the blending
ratio of resin 16 and bamboo fiber 17 is in a range of greater than
or equal to 5% by weight and smaller than or equal to 60% by
weight, the kneading effect when resin 16 and bamboo fiber 17 are
kneaded can be efficiently produced. Furthermore, the productivity
and the quality of diaphragm 1 are improved.
[0117] If the mixing ratio of bamboo fiber 17 is less than 5% by
weight, the effect of using bamboo fiber 17 is barely produced. If
the mixing ratio of bamboo fiber 17 is greater than 60% by weight,
a long time is required for the kneading of resin 16 and bamboo
fiber 17. Furthermore, since molding of diaphragm 1 using injection
molding becomes difficult, the productivity and dimension stability
lower, and the degree of freedom in the shape of diaphragm 1
decreases.
[0118] Bamboo fiber 17 of greater than or equal to 60% by weight
can be mixed in diaphragm 1 by using bamboo powder 19 or bamboo
charcoal 20 for bamboo fiber 17. In other words, when bamboo powder
19 or bamboo charcoal 20 is used for bamboo fiber 17, the mixing
ratio of bamboo fiber 17 with respect to resin 16 is preferably
greater than or equal to 5% by weight and smaller than or equal to
70% by weight. Effects such as enhancement of fluidity at the time
of kneading resin 16 and bamboo fiber 17 are efficiently produced
by using bamboo powder 19 or bamboo charcoal 20 for bamboo fiber
17. The enhancement in productivity and the enhancement in quality
of diaphragm 1 are thereby realized. Bamboo powder 19 or bamboo
charcoal 20 excels in dispersibility compared to bamboo fiber 17.
Bamboo fiber 17 up to 70% by weight thus can be uniformly
dispersed. Therefore, bamboo fiber 17 with a high concentration is
uniformly dispersed. Accordingly, diaphragm 1 having excellent
external appearance is obtained.
[0119] Moreover, when reinforcing diaphragm 1, when giving a slight
accent to the reproduction sound of speaker 10, when performing
sound quality adjustment by providing a peak to the sound pressure
frequency characteristics, and the like, reinforcing material 68
may be mixed in compound 15. As reinforcing material 68, for
example, mica, graphite, talc, calcium carbonate, clay, carbon
fiber, aramid fiber, and the like are used.
[0120] When mica is used for reinforcing material 68, the elastic
modulus of diaphragm 1 becomes higher. When graphite is used for
reinforcing material 68, enhancement of the elastic modulus and
enhancement of the internal loss of diaphragm 1 are realized. When
talc, calcium carbonate, or clay is used for reinforcing material
68, the internal loss of diaphragm 1 enhances.
[0121] A tough fiber such as carbon fiber may be used for
reinforcing material 68. When carbon fiber is used for reinforcing
material 68, the rigidity of diaphragm 1 increases and the elastic
modulus enhances.
[0122] When aramid fiber is used for reinforcing material 68,
bamboo fiber 17 and the aramid fiber entangle in time of heating
granulation when generating compound 15. Thus, the elastic modulus
does not lower and the internal loss enhances in diaphragm 1. When
microfibrillated aramid fiber miniaturized to the microfibrillated
state is used for reinforcing material 68, the aspect ratio of the
microfibrillated aramid fiber becomes large and the entanglement
between the fibers becomes strong. Diaphragm 1 realizing a high
elastic modulus and a high internal loss is thereby obtained.
[0123] The length of the microfibrillated aramid fiber used for
reinforcing material 68 is preferably greater than or equal to 0.2
mm and smaller than or equal to 3 mm. The effect of heating
granulation when obtaining compound 15 mixed with resin 16 and
bamboo fiber 17 is efficiently produced by including a
microfibrillated aramid fiber having a fiber length in a range of
greater than or equal to 0.2 mm and smaller than or equal to 3 mm
for reinforcing material 68. At the same time, the productivity and
the quality of diaphragm 1 are also improved.
[0124] If the fiber length of the microfibrillated aramid fiber is
shorter than 0.2 mm, the effect of the microfibrillated aramid
fiber is not efficiently exerted, and diaphragm 1 having high
elastic modulus is hardly obtained. If, on the other hand, the
fiber length of the microfibrillated aramid fiber is longer than 3
mm, secondary aggregation that occurs from the entanglement between
the microfibrillated aramid fibers easily occur, and dispersion
failure of the microfibrillated aramid fiber easily occurs. Thus, a
long time is required for kneading when reinforcing material 68 is
mixed. An aggregate of the microfibrillated aramid fiber may appear
on the surface of diaphragm 1, thereby affecting the external
appearance of speaker 10. Therefore, the productivity and the
quality of diaphragm 1 enhance if the fiber length of the
microfibrillated aramid fiber used for reinforcing material 68 is
within a range of greater than or equal to 0.2 mm and smaller than
or equal to 3 mm.
[0125] The average fiber diameter of the microfibrillated aramid
fiber used for reinforcing material 68 is preferably smaller than
or equal to 5 .mu.m. A typical fiber has higher elasticity as the
aspect ratio is larger. Therefore, the microfibrillated aramid
fiber miniaturized to the microfibrillated state of smaller than or
equal to 5 .mu.m has a relatively large aspect ratio, and high
elastic modulus can be expected. The entanglement between the
fibers does not become strong if the average fiber diameter of the
microfibrillated aramid fiber is greater than 5 .mu.m. Furthermore,
the bonding between resin 16 and bamboo fiber 17, or between bamboo
fiber 17 and bamboo fiber 17 becomes strong if the microfibrillated
aramid fiber partially exists at a part of the aramid fiber.
Therefore, high effect of reinforcing material 68 is obtained if
the average fiber diameter of the microfibrillated aramid fiber
used as reinforcing material 68 is smaller than to equal to 5
.mu.m, and a higher elastic modulus is expected on diaphragm 1.
[0126] Reinforcing material 68 is preferably mixed at greater than
or equal to 10% by weight in order for diaphragm 1 to obtain a
sufficient elastic modulus. The elastic modulus of diaphragm 1
enhances when the mixing ratio of reinforcing material 68
increases.
[0127] Compatibilizing agent 65 may be mixed in compound 15. The
compatibility between non-polar resin 16 such as PP and bamboo
fiber 17 improves by using compatibilizing agent 65 for compound
15. Thus, the features of bamboo fiber 17 are efficiently
produced.
[0128] In particular, a hydrolyzable long-chain alkylsilane is
preferably used for compatibilizing agent 65. The long-chain alkyl
group of the hydrolyzable long-chain alkylsilane is similar to the
olefin resin such as PP in terms of structure. Thus, satisfactory
compatibility is obtained in resin 16 and compatibilizing agent 65.
As a result, the compatibility between bamboo fiber 17 and resin 16
also increases, and the characteristics of diaphragm 1 enhances.
Therefore, bamboo fiber 17 and resin 16 such as the olefin resin
are strongly bonded by mixing hydrolyzable long-chain alkylsilane
in compound 15. Furthermore, hydrolyzable long-chain alkylsilane in
which an alkyl group has 6 or more carbon atoms is particularly
used. The hydrolyzable long-chain alkylsilane in which an alkyl
group has 6 or more carbon atoms has a long carbon chain, and thus
resin 16 and bamboo fiber 17 are strongly bonded. Light and high
rigid diaphragm 1 exhibiting the characteristics of bamboo fiber 17
is thereby obtained. If the hydrolyzable long-chain alkylsilane is
hexytrimethoxysilane or decyltrimethoxysilane, the above actions
are more effectively exerted. Compatibilizing agent 65 is not
limited to the hydrolyzable long-chain alkylsilane. For instance, a
so-called acid modified polypropylene resin modified with silane
coupling agent or maleic anhydride and the like, and given polarity
may be used for compatibilizing agent 65.
[0129] Coloring agent 71 such as a pigment may be mixed in compound
15. The color of diaphragm 1 is adjusted by including coloring
agent 71. In particular, so-called green-bamboo-colored diaphragm 1
is obtained by including coloring agent 71 having a green
component. Coloring agent 71 to be mixed is preferably an organic
phthalocyanine green or a mixture of phthalocyanine blue and
titanium yellow.
[0130] Such materials are combined and used for the material of
compound 15, so that the characteristic value of diaphragm 1 can be
freely adjusted at high accuracy. Diaphragm 1 then can have the
predetermined characteristics and the sound quality easily
adjusted.
[0131] In the realization of the predetermined characteristics and
the sound quality of diaphragm 1, deep know-how is required for
characteristic creation and sound creation of speaker 10. However,
in most times, adjustment is generally made through the following
methods. In other words, with respect to characteristic creation
and sound creation of speaker 10, adjustment of a certain extent
can be made by changing the parameters of the components of speaker
10. Thus, speaker 10 approaches the predetermined characteristics
and sound quality.
[0132] For instance, it is assumed that the parameters of other
components other than diaphragm 1 of the components of speaker 10
are constant. The parameter variable by diaphragm 1 includes an
area, a shape, a weight, surface thickness, and the like other than
the characteristic value of diaphragm 1. However, the area, shape,
weight, surface thickness, and the like of diaphragm 1 are more or
less determined at the initial stage in designing speaker 10. That
is, the sound pressure frequency characteristics and the sound
quality of speaker 10 are broadly determined by the conditions
other than the characteristic value of diaphragm 1.
[0133] In this case, unnecessary peak or dip produces on the sound
pressure frequency characteristics of speaker 10, and distortion
often produces greatly in a specific frequency band. The sound
quality of speaker 10 becomes a tone greatly dependent on the sound
pressure frequency characteristics. The cause of obtaining the
characteristics of speaker 10 is due to the area, shape, weight,
and surface thickness of diaphragm 1. It is often influenced, in
particular, by the vibration mode of diaphragm 1. In order to
improve such unnecessary peak or dip and the distortion, and
produce a satisfactory sound quality, the material of diaphragm 1
is appropriately selected. In this case, the material of diaphragm
1 is selected in the following procedure.
[0134] First, the material configuration assumed to satisfy the
sound pressure frequency characteristics, the sound quality, and
the reliability grade demanded on speaker 10 is selected for resin
16, bamboo fiber 17, and other mixing material thereof. In this
case, selection is made especially focusing on the reliability of
heat resistance grade and the like with respect to resin 16 that
becomes the base. A material in which the unique tone of resin 16
is close to a predetermined tone is selected.
[0135] Each material is then selected for the unnecessary peak or
the dip on the sound pressure frequency characteristics to delete.
In the case of a dip countermeasure, the material of resin 16
having a resonance point in the frequency where the dip produces is
selected. Adversely, in the peak countermeasure, the material of
resin 16 having internal loss in the frequency where the peak
produces is selected. Such material selection is made on resin 16,
bamboo fiber 17, and other mixing materials in view of the material
specific density, elastic modulus, internal loss, tone, resonance
frequency when molded to the shape of diaphragm 1, and the
like.
[0136] The selected material is then kneaded, and a master batch
pellet highly filled with bamboo fiber 17 is fabricated for
injection molding. Diaphragm 1 is obtained by injection molding
using the master batch pellet.
[0137] The characteristic value and the like of diaphragm 1
obtained in the above manner are then measured and evaluated.
Speaker 10 is experimentally manufactured using diaphragm 1.
Actually, the characteristics and the sound quality of
experimentally manufactured speaker 10 are measured and listened
to, and the selected material is ultimately evaluated. If the
predetermined characteristics and the sound quality are not
obtained by evaluation, such an experimental manufacturing process
is repeated over and over. Improvement is made on the material
selection and the blending ratio of the selected material, and
trial and error of material selection and the like is sequentially
repeated so as to approach the target characteristics and sound
quality.
[0138] Diaphragm 1 satisfies the predetermined characteristics and
sound quality by repeating the process of trial and error.
Diaphragm 1 very close to the predetermined characteristics and
sound quality is obtained.
[0139] If polylactic acid is used for resin 16, the compatibility
between resin 16 and bamboo fiber 17 improves as compared to when
PP is used. Furthermore, the compatibility between resin 16 and
bamboo fiber 17 further enhances by including tannin and the like
for compatibilizing agent 65.
[0140] Therefore, in the present invention, compound 15 is made of
a material mixed with resin 16 and bamboo fiber 17, which is then
injection molded to form speaker diaphragm 1. The degree of freedom
in setting the characteristic value of diaphragm 1 thus increases,
and in particular, high internal loss and humidity resistance
reliability of resin 16 are ensured while exhibiting high elastic
modulus, which is the feature of bamboo fiber 17. Diaphragm 1
excellent in external appearance and with enhanced productivity and
dimension stability is obtained. Diaphragm 1 has characteristics of
high sound quality, large output, and high reliability.
[0141] Furthermore, speaker 10 having high productivity excellent
in external appearance in which the degree of freedom in adjustment
of characteristics and sound quality is large, and humidity
resistance reliability and strength are ensured is realized by
configuring speaker 10 using diaphragm 1.
[0142] Therefore, speaker 10 includes inner magnetic type magnetic
circuit 5. However, speaker 10 is not limited to the configuration
including inner magnetic type magnetic circuit 5. For instance,
speaker 10 may be speaker 10 including outer magnetic type magnetic
circuit (not shown).
Embodiment 2
[0143] Embodiment 2 of the present invention will be described
using the drawings. The configurations similar to Embodiment 1 are
denoted with similar reference numerals, and the detailed
description will be omitted.
[0144] FIG. 5 is a cross-sectional view of speaker 10a according to
Embodiment 2 of the present invention. FIG. 6 is a cross-sectional
view of speaker frame 7 (hereinafter referred to as frame 7) used
in speaker 10a shown in FIG. 5. FIG. 7 is a partially detailed
cross sectional view of frame 7 shown in FIG. 6.
[0145] As compared to speaker 10 according to Embodiment 1, speaker
10a according to Embodiment 2 has diaphragm 1 replaced with speaker
diaphragm 1a (hereinafter referred to as diaphragm 1a), and frame
7a replaced with frame 7. Other configurations of speaker 10a
according to Embodiment 2 have configurations similar to speaker 10
according to Embodiment 1. Diaphragm 1a includes resin 16 but does
not include bamboo fiber 17. Similar to diaphragm 1, frame 7 is
made from compound 15 in which resin 16 and bamboo fiber 17, which
is a cellulose fiber, are mixed. The mechanical rigidity of frame 7
enhances by forming frame 7 by mixing bamboo fiber 17 to resin 16.
Moreover, the rigidity of frame 7 further enhances by including
microfibrillated bamboo fiber 18 miniaturized to the
microfibrillated state. As frame 7 includes bamboo fiber 17 or
fiber 18, speaker 10a having light weight and large internal loss
compared to when including the inorganic filler is realized. Frame
7 is preferably formed by injection molding compound 15.
[0146] Resin 16 preferably uses a crystalline or non-crystalline
olefin resin. Satisfactory moldability of frame 7 is realized by
using an olefin resin for resin 16. The crystalline resin and/or
the non-crystalline resin are used depending on the application of
resin 16. Thus, resin 16 satisfies an optimum characteristic value
for a resin material.
[0147] Polypropylene (hereinafter referred to as PP) is used for
resin 16. The PP is generally easily available, and is easily
injection molded. Furthermore, frame 7 having large internal loss
is obtained by using PP for resin 16. However, the material
selected for resin 16 is not limited to PP. The material selected
for resin 16 may be appropriately selected such that a desired
characteristic value for frame 7 is obtained.
[0148] An engineering plastic may be used for resin 16, not limited
to PP. Frame 7 excellent in heat resistance or solvent resistance
is obtained by using the engineering plastic for resin 16. The
engineering plastic used in resin 16 may be polyacetal, polyamide,
polycarbonate and polybutyleneterephthalate.
[0149] In view of environmental consideration, resin 16 may use a
biodegradable plastic typified by polylactic acid.
Environment-friendly frame 7 of high performance that does not
require a special disposal method and that avoids extra discharge
of carbon dioxide in disposal is obtained by using the
biodegradable plastic for resin 16. Other than polylactic acid, as
the biodegradable plastic, examples such as polycaprolactam, a
modified polyvinyl alcohol, casein plastics, and the like, are
used. The polylactic acid excels in transparency and rigidity
compared to other biodegradable plastic. The polylactic acid also
has satisfactory compatibility with the cellulose of bamboo fiber
17, and thus easily fixes on the surface of bamboo fiber 17. Thus,
environment-friendly frame 7 of high rigidity in which the external
appearance color of bamboo fiber 17 is not affected is obtained by
using polylactic acid for resin 16.
[0150] A configuration example of frame 7 when using PP for resin
16 will now be described. First, a pellet in which bamboo fiber 17
or bamboo fiber 17 and reinforcing material 68 are kneaded to resin
16 is fabricated. A plate having a thickness of 0.3 mm is obtained
by injection molding using the pellet. After measuring the specific
gravity of the obtained plate, a part of the plate is cut out, and
a sample having a size of 32 mm.times.5 mm is obtained. The elastic
modulus and the internal loss of the obtained sample are measured,
and compared with the characteristics of a plate not containing
bamboo fiber 17. The comparison result is shown in table 1.
TABLE-US-00001 TABLE 1 Reinforcing material Elastic Bamboo Glass
Specific modulus Internal Sample fiber Mica fiber gravity (MPa)
loss 1 0 0 0 0.91 1660 0.060 2 0 25 15 1.17 3500 0.040 3 30 0 0
1.04 3000 0.055 4 40 0 0 1.06 4000 0.050 5 20 10 0 1.07 3500
0.055
[0151] As shown in table 1, the plate containing bamboo fiber has
characteristics of low specific gravity, high elastic modulus and
high internal loss compared to the plate not containing bamboo
fiber 17. In other words, a plate of sample 1 does not contain
bamboo fiber 17 and reinforcing material 68. The plate of sample 1
thus has low specific gravity and high internal loss but low
elastic modulus. A plate of sample 2 does not contain bamboo fiber
17 but contains reinforcing material 68. The plate of sample 2 thus
has high elastic modulus but high specific gravity and low internal
loss. As opposed to sample 1 and sample 2, plates of sample 3,
sample 4, and sample 5 contain bamboo fiber 17. Thus, the plates of
sample 3, sample 4, and sample 5 have characteristics of low
specific gravity, high elastic modulus and high internal loss.
[0152] Therefore, the plate has extremely effective characteristics
by containing bamboo fiber 17. As bamboo fiber 17 has large
internal loss, the plate containing bamboo fiber 17 has a high
effect of absorbing unnecessary vibration. The elastic modulus
enhances compared to the plate configured with simple body of resin
16. The characteristics of the plate of each material configuration
shown in table 1 are obtained by measuring the sample having a size
of 32 mm.times.5 mm. However, the characteristic values described
in table 1 are also applicable when each material configuration is
actually applied to frame 7.
[0153] Furthermore, the entanglement between bamboo fibers 17
becomes stronger by mixing microfibrillated bamboo fiber 18
miniaturized to the microfibrillated state to frame 7. As a result,
frame 7 of large strength and elastic modulus is obtained.
[0154] The fiber length of fiber 18 mixed in frame 7 is preferably
greater than or equal to 0.2 mm and smaller than or equal to 3 mm.
The effect of heating granulation when obtaining compound 15 mixed
with resin 16 and bamboo fiber 17 is efficiently produced by
including fiber 18 having a fiber length in a range of greater than
or equal to 0.2 mm and smaller than or equal to 3 mm for frame 7.
The productivity and the quality of frame 7 also enhance.
[0155] If the fiber length of fiber 18 is shorter than 0.2 mm, the
effect of fiber 18 is not efficiently produced, and frame 7 of
sufficient strength is hardly obtained. If, on the other hand, the
fiber length of fiber 18 is longer than 3 mm, secondary aggregation
that occurs from the entanglement between fibers 18 easily occur,
and dispersion failure of fiber 18 easily occurs. Thus, it is
required to take a long time for the kneading of resin 16 and
bamboo fiber 17. An aggregate of fiber 18 may appear on the surface
of frame 7, thereby external appearance of speaker 10 may be
damaged. Therefore, the productivity and the quality of frame 7
enhance if the fiber length of fiber 18 to be mixed in frame 7 is
within a range of greater than or equal to 0.2 mm and smaller than
or equal to 3 mm.
[0156] The fiber diameter of fiber 18 to be mixed in frame 7 is
preferably smaller than or equal to 10 .mu.m. The entanglement
between the fibers is not strong if the average fiber diameter of
fiber 18 is greater than 10 .mu.m. Moreover, high elastic modulus
can be expected for the fiber having a large aspect ratio.
Therefore, the synergistic effect of higher elastic modulus of
single body of bamboo fiber 17 and enhanced bonding strength
between the fibers is obtained if the average fiber diameter of
fiber 18 to be mixed in frame 7 is smaller than to equal to 10
.mu.m, and frame 7 having higher elastic modulus is obtained.
[0157] If bamboo fiber 17 is contained in compound 15 in great
amount, bamboo powder 19 or bamboo charcoal 20 may be used for a
part of or all of bamboo fiber 17. The lowering of fluidity when
frame 7 is formed by injection molding is suppressed even when the
content of bamboo becomes high concentration by including bamboo
powder 19 or bamboo charcoal 20 in frame 7. Thus, when the bamboo
component is contained at the same concentration, the moldability
of frame 7 is more improved as compared with forming only by bamboo
fiber 17.
[0158] The mixing ratio of bamboo fiber 17 with respect to resin 16
is preferably greater than or equal to 15% by weight and smaller
than or equal to 60% by weight. If the blending ratio of resin 16
and bamboo fiber 17 is in a range of greater than or equal to 15%
by weight and smaller than or equal to 60% by weight, the kneading
effect when resin 16 and bamboo fiber 17 are kneaded can be
efficiently produced. Furthermore, the productivity and the quality
of frame 7 enhance.
[0159] If the mixing ratio of bamboo fiber 17 is less than 15% by
weight, the features of bamboo fiber 17, high elasticity and high
strength, cannot be produced. If the mixing ratio of bamboo fiber
17 is greater than 60% by weight, uniform dispersion of bamboo
fiber 17 is difficult. The fluidity of compound 15 also lowers.
Thus, as molding of frame 7 using injection molding becomes
difficult, the productivity and dimension stability lower, and the
degree of freedom in the shape of frame 7 decreases.
[0160] Furthermore, bamboo fiber 17 of greater than or equal to 60%
by weight can be mixed in frame 7 by using bamboo powder 19 or
bamboo charcoal 20 for bamboo fiber 17. In other words, when bamboo
powder 19 or bamboo charcoal 20 is used for bamboo fiber 17, the
mixing ratio of bamboo fiber 17 with respect to resin 16 is
preferably greater than or equal to 15% by weight and smaller than
or equal to 70% by weight. Effects such as enhancement of fluidity
when kneading resin 16 and bamboo fiber 17 are efficiently produced
by using bamboo powder 19 or bamboo charcoal 20 for bamboo fiber
17. The enhancement in productivity and the enhancement in quality
of frame 7 are thereby realized. Bamboo powder 19 or bamboo
charcoal 20 excels in dispersibility compared to bamboo fiber 17.
Bamboo fiber 17 up to 70% by weight thus can be uniformly
dispersed. Bamboo fiber 17 with a high concentration is thus
uniformly dispersed. Frame 7 having excellent external appearance
is thereby obtained.
[0161] Further, when the elastic modulus of frame 7 is enhanced,
reinforcing material 68 may be mixed in compound 15. Reinforcing
material 68 may be either glass fiber or mica, or combination of
glass fiber and mica, and the like. Other than glass fiber and
mica, reinforcing material 68 may be inorganic filler or organic
fiber. Talc, graphite, glass flake and the like can be used for the
inorganic filler. Aramid fiber, carbon fiber, and the like can be
used for the organic fiber. Reinforcing material 68 may be a
material combining such materials. The microfibrillated aramid
fiber obtained by miniaturizing the aramid fiber to the
microfibrillated state may be used for reinforcing material 68. The
microfibrillated aramid fiber has a large aspect ratio, and the
entanglement between the fibers becomes strong. Therefore, frame 7
having high strength and high rigidity is obtained if the
microfibrillated aramid fiber is used for reinforcing material
68.
[0162] When reinforcing material 68 is mixed in compound 15, the
mixing ratio of reinforcing material 68 is preferably greater than
or equal to 10% by weight and less than or equal to 25% by weight.
Reinforcing material 68 is preferably mixed at greater than or
equal to 10% by weight in order for frame 7 to obtain sufficient
elastic modulus. The elastic modulus of frame 7 enhances when the
mixing ratio of reinforcing material 68 increases. However, the
specific gravity of frame 7 tends to become large and the internal
loss tends to decrease. Therefore, the mixing ratio of reinforcing
material 68 is preferably less than or equal to 25% by weight.
[0163] Compatibilizing agent 65 may be mixed in compound 15. The
compatibility between non-polar resin 16 such as PP and bamboo
fiber 17 improves by using compatibilizing agent 65 for compound
15. Thus, the features of bamboo fiber 17 are efficiently
exerted.
[0164] In particular, a hydrolyzable long-chain alkylsilane is
preferably used for compatibilizing agent 65. The long-chain alkyl
group of the hydrolyzable long-chain alkylsilane is similar to the
olefin resin such as PP in terms of structure. Thus, satisfactory
compatibility is obtained in resin 16 and compatibilizing agent 65.
As a result, the compatibility between bamboo fiber 17 and resin 16
also increases, and the characteristics of diaphragm 1 enhances.
Therefore, bamboo fiber 17 and resin 16 such as the olefin resin
are strongly bonded by mixing hydrolyzable long-chain alkylsilane
to compound 15. Furthermore, hydrolyzable long-chain alkylsilane in
which an alkyl group has 6 or more carbon atoms is particularly
used. The hydrolyzable long-chain alkylsilane in which an alkyl
group is six or more carbon atoms has a long carbon chain, and thus
resin 16 and bamboo fiber 17 are strongly bonded. Light and high
rigid frame 7 exhibiting the characteristics of bamboo fiber 17 is
thereby obtained. If the hydrolyzable long-chain alkylsilane is
hexytrimethoxysilane or decyltrimethoxysilane, the above actions
are more effectively exerted. Compatibilizing agent 65 is not
limited to the hydrolyzable long-chain alkylsilane. For instance, a
so-called acid modified polypropylene resin modified with silane
coupling agent or maleic anhydride and the like, and given polarity
may be used for compatibilizing agent 65.
[0165] Coloring agent 71 such as a pigment may be mixed in compound
15. The color of frame 7 is adjusted by including coloring agent
71. In particular, so-called bamboo-colored frame 7 is obtained by
including coloring agent 71 having a green component. Coloring
agent 71 to be mixed is preferably an organic phthalocyanine green
or a mixture of phthalocyanine blue and titanium yellow.
[0166] Such materials are combined and used for the material of
compound 15, so that the characteristic value of frame 7 can be
freely adjusted at high accuracy. Predetermined characteristics and
sound quality are thus easily adjusted in flame 7.
[0167] Therefore, the present invention forms speaker frame 7 by
forming compound 15 with the material in which resin 16 and bamboo
fiber 17 are mixed, and injection molding the same. Speaker frame 7
having characteristics of low specific gravity, high elastic
modulus and high internal loss and excellent in productivity with
high quality is thereby obtained. Frame 7 also has characteristics
of high sound quality, large output, and high reliability.
[0168] Furthermore, light speaker 10a excellent in external
appearance and having high productivity is realized by configuring
speaker 10a using frame 7 having characteristics of low specific
gravity, high elastic modulus, and high internal loss.
[0169] Bamboo fiber 17 used in diaphragm 1 as described in
Embodiment 1 may be used for bamboo fiber 17 used in frame 7. Frame
7 is given characteristics similar to diaphragm 1 and the
characteristics of speaker 10a enhance by including bamboo fiber 17
and microfibrillated bamboo fiber 18 in frame 7.
[0170] Diaphragm is configuring speaker 10a has been described as
diaphragm is not containing bamboo fiber 17. However, as described
in Embodiment 1, light speaker 10a having high productivity
excellent in external appearance in which the degree of freedom in
adjustment of characteristics and sound quality is large, and
humidity resistance reliability and strength are ensured is
realized by using diaphragm 1 containing bamboo fiber 17 in speaker
10a.
Embodiment 3
[0171] Embodiment 3 of the present invention will be described
using the drawings. The configurations similar to Embodiments 1 and
2 are denoted with similar reference numerals, and the detailed
description will be omitted.
[0172] FIG. 8 is a cross-sectional view of speaker 10b according to
Embodiment 3 of the present invention. FIG. 9 is a cross-sectional
view of speaker dust cap 11 (hereinafter referred to as cap 11)
used in speaker 10b shown in FIG. 8. FIG. 10 is a partially
detailed cross sectional view of cap 11 shown in FIG. 9.
[0173] As compared to speaker 10 according to Embodiment 1, speaker
10b according to Embodiment 3 has diaphragm 1 replaced with speaker
diaphragm 1a, and cap 11a replaced with cap 11. Other
configurations of speaker 10b according to Embodiment 3 have
configurations similar to speaker 10 according to Embodiment 1. As
compared to speaker 10a according to Embodiment 2, speaker 10b
according to Embodiment 3 has frame 7 replaced with frame 7a, and
cap 11a replaced with cap 11. Other configurations of speaker 10b
according to Embodiment 3 have configurations similar to speaker
10a according to Embodiment 2.
[0174] Diaphragm is includes resin 16 but does not include bamboo
fiber 17. Frame 7a includes resin 16 but does not include bamboo
fiber 17. Furthermore, similar to diaphragm 1 and frame 7, cap 11
is made from compound 15 in which resin 16 and bamboo fiber 17,
which is a cellulose fiber, are mixed. The mechanical rigidity of
cap 11 enhances by forming cap 11 by mixing bamboo fiber 17 to
resin 16. Moreover, the rigidity of cap 11 further enhances by
including microfibrillated bamboo fiber 18 miniaturized to the
microfibrillated state. As cap 11 includes bamboo fiber 17 or fiber
18, speaker 10b of light weight and large internal loss compared to
when including an inorganic filler is realized. Cap 11 is
preferably formed by injection molding compound 15.
[0175] Bamboo fiber 17 used in diaphragm 1 as described in
Embodiment 1 can be used for bamboo fiber 17 used in cap 11. Cap 11
is given characteristics similar to diaphragm 1 and frame 7, and
the characteristics of speaker 10b enhance by including bamboo
fiber 17 and fiber 18 in cap 11.
[0176] Bamboo powder 19 or bamboo charcoal 20 may be used for a
part of or all of bamboo fiber 17. When bamboo powder 19 or bamboo
charcoal 20 is used in cap 11, the fluidity when formed through
injection molding enhances and the moldability improves as compared
to cap 11 formed only with bamboo fiber 17 if the concentration of
the bamboo component of cap 11 is the same.
[0177] Resin 16 preferably uses a crystalline or non-crystalline
olefin resin. Satisfactory moldability of cap 11 is realized by
using the olefin resin for resin 16. The crystalline resin and/or
the non-crystalline resin are used depending on the application of
resin 16. Thus, resin 16 satisfies an optimum characteristic value
for a resin material.
[0178] Polypropylene is used for resin 16. The PP is generally
easily available, and is easily injection molded. Furthermore,
inexpensive cap 11 excellent in moldability and having a relatively
high heat resistance is easily obtained by using PP for resin 16.
However, the material selected for resin 16 is not limited to PP.
The material selected for resin 16 may be appropriately selected
such that a desired characteristic value for cap 11 is
obtained.
[0179] An engineering plastic may be used for resin 16. Cap 11
excellent in heat resistance or solvent resistance is obtained by
using the engineering plastic for resin 16. Examples of the
engineering plastic used in resin 16 include polyacetal, polyamide,
polycarbonate and polybutyleneterephthalate.
[0180] In view of environmental consideration, resin 16 may use a
biodegradable plastic typified by polylactic acid.
Environment-friendly cap 11 of high performance that does not
require a special disposal method and that avoids extra discharge
of carbon dioxide in disposal is obtained by using a biodegradable
plastic for resin 16. Other than polylactic acid, the biodegradable
plastic may be polycaprolactam, a modified polyvinyl alcohol,
casein plastics, and the like. The polylactic acid excels in
transparency and rigidity as compared to other biodegradable
plastic. The polylactic acid also has satisfactory compatibility
with the cellulose of bamboo fiber 17, and thus easily fixes on the
surface of bamboo fiber 17. Thus, environment-friendly cap 11
having high rigidity in which the external appearance color of
bamboo fiber 17 is not affected is obtained by using polylactic
acid for resin 16.
[0181] Cap 11 that reproduces natural and light tone is obtained by
including bamboo fiber 17 in cap 11. Thus, a dark and standardized
tone is suppressed as compared to the speaker dust cap formed only
with resin 16. Furthermore, cap 11 having high elastic modulus
compared to the speaker dust cap including other pulp material is
obtained. Thus, the degree of freedom for adjusting the
characteristics of cap 11 increases.
[0182] The entanglement between bamboo fibers 17 becomes stronger
by mixing fiber 18 in mixed cap 11. As a result, cap 1 with large
strength and elastic modulus is obtained. Therefore, cap 11 with
enhanced sound pressure level in the high tone region as acoustic
feature is obtained. Consequently, speaker 10b having clear and
powerful sound quality in the high tone region is obtained.
[0183] The fiber length of fiber 18 mixed in cap 11 is preferably
greater than or equal to 0.2 mm and smaller than or equal to 3 mm.
The effect of heating granulation when obtaining compound 15 mixed
with resin 16 and bamboo fiber 17 is efficiently produced by
including fiber 18 having a fiber length in a range of greater than
or equal to 0.2 mm and smaller than or equal to 3 mm for cap 11.
The productivity and the quality of cap 11 also enhance.
[0184] The average fiber diameter of fiber 18 to be mixed in cap 11
is preferably smaller than or equal to 10 .mu.m. Fiber 18 having a
relatively large aspect ratio and high elastic modulus can be
expected. Therefore, the synergistic effect of higher elastic
modulus of a single body of fiber 18 and enhanced bonding strength
between the fibers is obtained if the average fiber diameter of
fiber 18 to be mixed in cap 11 is smaller than to equal to 10
.mu.m, and cap 11 having higher elastic modulus is obtained.
[0185] The mixing ratio of bamboo fiber 17 with respect to resin 16
used in cap 11 is preferably greater than or equal to 5% by weight
and smaller than or equal to 70% by weight. If the blending ratio
of resin 16 and bamboo fiber 17 is in a range of greater than or
equal to 5% by weight and smaller than or equal to 70% by weight,
the kneading effect when resin 16 and bamboo fiber 17 are kneaded
can be efficiently produced. Furthermore, the productivity and the
quality of cap 11 are improved. Bamboo powder 19 or bamboo charcoal
20 is preferably mixed in bamboo fiber 17 if the blending ratio of
bamboo fiber 17 excesses 60% by weight.
[0186] If the mixing ratio of bamboo fiber 17 is less than 5% by
weight, the effect of including bamboo fiber 17 is barely produced.
If the mixing ratio of bamboo fiber 17 is greater than 70% by
weight, a long time is required for the kneading of resin 16 and
bamboo fiber 17. Furthermore, as molding of cap 11 using injection
molding becomes difficult, the productivity and dimension stability
lower, and the degree of freedom in the shape of cap 11
decreases.
[0187] Moreover, when reinforcing cap 11, when giving a slight
accent to the reproduction sound of speaker 10b, when performing
sound quality adjustment by providing a peak to the sound pressure
frequency characteristics, and the like, reinforcing material 68
may be mixed in compound 15. Reinforcing material 68 may be mica,
titanium dioxide, and the like. The elastic modulus of cap 11
becomes higher if mica or titanium dioxide is used for reinforcing
material 68.
[0188] Coloring agent 71 such as a pigment may be mixed in compound
15. The color of cap 11 is adjusted by including coloring agent 71.
In particular, so-called bamboo-colored cap 11 is obtained by
including coloring agent 71 having a green component. Coloring
agent 71 to be mixed is preferably an organic phthalocyanine green
or a mixture of phthalocyanine blue and titanium yellow.
[0189] Through combination of such materials, the characteristic
value of cap 11 can be freely adjusted at high accuracy. Speaker
10b having the predetermined characteristics and the sound quality
is thus easily obtained.
[0190] Therefore, the present invention forms cap 11 by forming
compound 15 with the material in which resin 16 and bamboo fiber 17
are mixed, and injection molding the same. The degree of freedom in
setting the characteristic value of the cap 11 increases, and in
particular, high internal loss and humidity resistance reliability
of resin 16 are ensured while achieving high elastic modulus or the
feature of bamboo fiber 17. Cap 11 excellent in external appearance
and having enhanced productivity and dimension stability is
obtained. Cap 11 also has characteristics of high sound quality,
large output, and high reliability.
[0191] Speaker 10b using cap 11 having sufficient rigidity and
toughness is configured by forming speaker 10b using cap 11. The
sound pressure level in high tone region thus enhances. As a
result, speaker 10b having clear and powerful sound quality in the
high tone region is thus obtained. Furthermore, speaker 10b also
reproduces clear deep bass in the low tone region. Speaker 10b has
an excellent sound quality with satisfactory sound image
localization having high clarity and definite edge as a whole.
Speaker 10b also reproduces tone with reduced distortion
feeling.
[0192] Diaphragm 1a and frame 7a configuring speaker 10b have been
described as diaphragm 1a and frame 7a not containing bamboo fiber
17. However, as described in Embodiment 1 or 2, light speaker 10b
having high productivity excellent in external appearance in which
the degree of freedom in adjustment of sound quality is large, and
humidity resistance reliability and strength are ensured is
realized by using diaphragm 1 containing bamboo fiber 17, or frame
7 containing bamboo fiber 17 in speaker 10b.
Embodiment 4
[0193] Embodiment 4 of the present invention will be described
using the drawings. The same reference numerals are denoted for the
configurations same as Embodiments 1 to 3, and the detailed
description will be omitted.
[0194] FIG. 11 is an external appearance view of an electronic
equipment in Embodiment 4 of the present invention. As shown in
FIG. 11, audio mini-component system 26 (hereinafter referred to as
component 26) serving as the electronic equipment includes speaker
system 21 (hereinafter referred to as system 21), amplifier 23, and
operation unit 25. Speaker 10, 10a, 10b is incorporated in
enclosure 22 to configure system 21. Amplifier 23 includes
amplifier circuit 24 for amplifying an electric signal to input to
system 21. Operation unit 24 including a player outputs a source to
input to amplifier 23. Amplifier 23, operation unit 25, and
enclosure 22 configure main body 27 of component 26. Speaker 10,
10a, 10b is attached to main body 27. Speaker 10, 10a, 10b
described in the Embodiments 1 to 3 may be used for speaker 10,
10a, 10b. Voice coil 8 of speaker 10, 10a, 10b is supplied with
power from amplifier 23 of main body 27. This causes diaphragm 1,
is to emit sound. According to such configuration, component 26
having highly accurate characteristics, sound and design that are
not realized in the convention of the related art is obtained.
[0195] Audio mini-component 26 has been described as an example
where speaker 10, 10a, 10b is applied to an electronic equipment.
However, the application example of speaker 10, 10a, 10b to an
equipment is not limited thereto. For instance, application can be
made to a portable audio equipment that can be carried around,
charging system thereof, and the like. Furthermore, application can
be widely made and developed to video equipments such as liquid
crystal television and plasma display television, information
communication equipments such as mobile telephone, electronic
equipments such as computer related equipment, and the like.
Embodiment 5
[0196] Embodiment 5 of the present invention will be described
using the drawings. The same reference numerals are denoted for the
configurations same as Embodiments 1 to 4, and the detailed
description will be omitted. FIG. 12 is a cross-sectional view of
automobile 50 serving as a moving body device according to
Embodiment 5 of the present invention. As shown in FIG. 12,
automobile 50 includes body 55, seat 58, drive unit 53, steering
54, front wheel 56, and rear wheel 57. Seat 58 and steering 54 are
installed in a vehicle interior arranged in body 55, and drive unit
53 is installed in machine room 59 arranged in body 55. Steering 54
operates front wheel 56 which is a steering wheel. Drive unit 53
includes an engine or a motor, and drives rear wheel 57 which is a
drive wheel. Drive unit 53 may drive front wheel 56. Front wheel 56
and rear wheel 57 support body 55. Rear tray 51 arranged in the
interior of body 55 of automobile 50 incorporates speaker 10, 10a,
10b to be used as a part of a car navigation system or a car audio
system. In other words, speaker 10, 10a, 10b is supplied with power
from automobile 50 which is a main body. That is, speaker 10, 10a,
10b is input with an input signal from automobile 50. Automobile 50
may include an amplifier circuit for amplifying the input signal.
Speaker 10, 10a, 10b described in the Embodiments 1 to 3 may be
used for speaker 10, 10a, 10b.
[0197] Not limited to rear tray 51, speaker 10, 10a, 10b may be
attached to any location in automobile 50 such as front panel 52,
door (not shown), and side panel (not shown). Automobile 50 used as
a part of the car navigation system or the car audio is thereby
configured.
[0198] A moving body device exhibiting the features of speaker 10,
10a, 10b, and having highly accurate characteristics, sound, and
design is realized by configuring the moving body device in the
above manner. As a result, enhancement of sound quality and degree
of freedom in acoustic design of the moving body device such as
automobile 50 mounted with speaker 10, 10a, 10b are obtained.
[0199] The moving body device mounted with speaker 10, 10a, 10b has
been described using automobile 50. However, the moving body device
is not limited to automobile 50, and similar effects are also
obtained with moving body device such as a bicycle, a motorcycle, a
train, and an airplane.
Embodiment 6
[0200] Embodiment 6 of the present invention will be described
using the drawings. The same reference numerals are denoted for the
configurations same as Embodiments 1 to 5, and the detailed
description will be omitted.
[0201] FIG. 13 is a process chart showing the method for
manufacturing a speaker component according to Embodiment 6 of the
present invention. A method for manufacturing speaker diaphragm 1
as a typical example of speaker component will be described below
with reference to FIG. 13.
[0202] First, in the grinding step, polypropylene pellet 61, which
is the material of resin 16, is grinded using a grinder to produce
granulated polypropylene resin 62 (hereinafter referred to as resin
62) (step S01).
[0203] In the miniaturization step, fiber 63 is immersed in water
to prepare a fiber solution (not shown) of greater than or equal to
0.5% by weight and smaller than or equal to 1.5% by weight. Fiber
63 contained in the prepared fiber solution is miniaturized to the
microfibrillated state using a cutter. That is, the cutter impinges
the fiber solution to the container wall at high speed at a
pressure difference of greater than or equal to 10 MPa, and rapidly
reduces speed. The shear force is thereby applied on fiber 63. The
operation of applying the shear force to fiber 63 is repeatedly
performed to generate microfibrillated fiber 64 (hereinafter
referred to as fiber 64) miniaturized to the microfibrillated state
(step S02).
[0204] If the concentration of fiber 63 in the fiber solution is
greater than 1.5% by weight, pressure is difficult to apply on
fiber 63, and fiber 63 is difficult to be microfibrillated. If the
concentration of fiber 63 in the fiber solution is smaller than
0.5% by weight, the time required for micro-fibrillating becomes
long. Thus, the productivity of fiber 64 is poor, thereby leading
to increase in cost. Therefore, the concentration of fiber 63 in
the fiber solution preferably has a concentration of greater than
or equal to 0.5% by weight and smaller than or equal to 1.5% by
weight. The concentration of fiber 63 in the fiber solution is
adjusted by adjusting the amount of moisture (not shown) contained
in the fiber solution.
[0205] In the miniaturization step, if the pressure difference
applied on the fiber solution is smaller than 10 MPa, sufficient
shear force is not applied on fiber 63, and thus micro-fibrillating
is difficult. Furthermore, the number of times to collide on the
container wall at high speed to generate fiber 64 increases, and
the productivity of fiber 64 lowers.
[0206] Then, in the compounding step, resin 62, fiber 63, and fiber
64 are compounded using a mixer to produce compound 15 (step S03).
The compounding step at least includes a substitution step in which
resin 62 and moisture contained in fiber 64 are substituted. The
adaptation of resin 62 and fiber 64 becomes satisfactory, and
compounded compound 15 is efficiently generated.
[0207] In the substitution step, the moisture to be substituted is
the moisture contained when miniaturizing fiber 63 to the
microfibrillated state in the miniaturization step. In other words,
in the substitution step, the moisture contained in resin 64 is
replaced with resin 62. Thus, secondary aggregation of resin 62 or
fiber 64 is prevented in the substitution step. As a result, the
dispersibility of resin 62 and fibers 63, 64 configuring compound
15 improves.
[0208] The preferred method for the substitution step is a
substitution method in which resin 62 and moisture contained in
fiber 64 are substituted and compounded through heating and
drying.
[0209] In such substitution method, resin 62, fiber 63, and fiber
64 are input to the mixer and then heated and dried. The moisture
contained in fiber 64 then evaporates, and at the same time, resin
62 is thermally fused, whereby the moisture and resin 62 are
substituted. As a result, the entanglement between resin 62 and
fibers 63, 64 becomes strong, and the adaptation becomes more
satisfactory. Resin 62, and fibers 63, 64 are mixed using the
mixer. The entanglement between fiber 63 and fiber 64 then becomes
stronger. As a result, resin 62 and fibers 63, 64 are efficiently
compounded.
[0210] Therefore, in the compounding step, the adaptation of resin
62 and fibers 63, 64 becomes more satisfactory, and uniformly
dispersed compound 15 is obtained. Compatibilizing agent 65 may be
added in the compounding step. Resin 62 or fibers 63, 64 are
subjected to surface treatment by adding compatibilizing agent 65,
whereby adhesiveness of resin 62 and fibers 63, 64 becomes
stronger. Compatibilizing agent 65 may be added to resin 62 or
fibers 63, 64 before the compounding step.
[0211] The hydrolyzable long-chain alkylsilane having 6 or more
carbon atoms is preferably used for compatibilizing agent 65. If
the hydrolyzable long-chain alkylsilane is used for compatibilizing
agent 65, for example, hexytrimethoxysilane or
decyltrimethoxysilane is used. The acid modified polypropylene
resin modified with acid may be used to enhance the adhesiveness of
resin 62 and fibers 63, 64.
[0212] In the molding step, compound 15 is injected and molded
while being heated by the injection molding machine to the inside
of molding die 72 of diaphragm 1. Diaphragm 1 is thereby obtained
(step S04).
[0213] Finally, in the cooling step, diaphragm 1 is cooled and
solidified, and then taken out from molding die 72 (step S05). The
molding step may include the cooling step.
[0214] Through the steps described above, the adaptation of resin
62 and fibers 63, 64 becomes more satisfactory, and the
entanglement between the fibers becomes stronger. Thus, diaphragm 1
in which resin 62 and fibers 63, 64 are uniformly dispersed is
obtained. The method for manufacturing diaphragm 1 is established
as above.
[0215] The above-described manufacturing method may further include
a pelletization step (step S11) before the molding step. In the
pelletization step, compound 15 is again pelletized using a pellet
molding machine for the purpose of further strengthening the
adaptation of resin 62 and fibers 63, 64. Microfibrillated fiber
compound pellet 67 (hereinafter referred to as pellet 67) of
compound 15 is thereby obtained. Obtained pellet 67 is then
injected in the injection molding machine in the molding step. The
dispersibility of fibers 63, 64 to resin 62 further enhances by
providing the pelletization step and kneading compound 15.
[0216] A mixing step (step S12) may be provided at the same time as
or after the compounding step. In the mixing step, reinforcing
material 68 such as mica or material such as diluting resin 69,
fluidity modifier 70 (hereinafter referred to as modifier 70), and
coloring agent 71 is additionally mixed in compound 15. Diaphragm 1
in which the characteristics and the functions are further improved
is thereby obtained.
[0217] In other words, the rigidity of diaphragm 1 enhances by
mixing reinforcing material 68 such as mica. Furthermore, blending
adjustment of resin 62 and fibers 63, 64 is performed by mixing
dilution resin 69, and the characteristics of diaphragm 1 are fine
tuned. Thus, speaker 10 having the speaker characteristics and the
sound quality complying with the respective purpose is easily
obtained.
[0218] The material injection to molding die 72 in the same
injecting conditions is facilitated in the molding step by mixing
modifier 70. Diaphragm 1 having thin thickness or a large degree of
freedom in shape is thus easily injection molded. The injecting
conditions mean various conditions for injection molding such as
injection pressure, injection speed, injection temperature, and the
like. The external appearance color of diaphragm 1 is freely
selected by mixing coloring agent 71. Diaphragm 1 excellent in
designability is thus easily obtained. Moreover, reinforcing
material 68, or dilution resin 69, modifier 70, and coloring agent
71 may be variously combined and mixed.
[0219] Mica, talc, graphite, and calcium carbonate may be used
alone or in combination for reinforcing material 68. Clay, carbon
fiber, aramid fiber, glass flake, titanium dioxide, and the like
may be used for reinforcing material 68. Calcium stearate or fatty
acid amide is used for modifier 70. A dye material such as a
general pigment that does not change in quality at the injection
temperature in the molding step is selected and used for coloring
agent 71. Phthalocyanine green or a mixture of phthalocyanine blue
and titanium yellow may be used for coloring agent 71.
[0220] The mixing step may be performed simultaneously with the
compounding step. The mixing step may be performed between the
compounding step and the pelletization step. Furthermore, dilution
resin 69 other than polypropylene resin may be used and polymer
blended with resin 62 in the mixing step.
[0221] Therefore, the adaptation of resin 62 and fibers 63, 64
enhances by manufacturing diaphragm 1 using the manufacturing
method of the present embodiment. Resin 62 and fibers 63, 64 are
thus evenly distributed. At the same time, the entanglement between
fibers 63, 64 also becomes stronger. As a result, speaker 10 using
diaphragm 1 has large degree of freedom in the adjustment of the
speaker characteristics and the adjustment of the sound quality.
Furthermore, diaphragm 1 and speaker 10 with excellent external
appearance in which the reliability with respect to humidity
resistance or water resistance is improved are obtained. Diaphragm
1 having characteristics of high elastic modulus and high strength
is obtained while exhibiting the features of fiber 63. Diaphragm 1
is stably provided at high productivity according to the
manufacturing method described above.
[0222] Diaphragm 1 is obtained as molding die 72 used in the
molding step is molding die 72 for diaphragm 1. Similarly, frame 7
is obtained as molding die 72 for frame 7 is used in the molding
step. Furthermore, cap 11 is obtained as molding die 72 for cap 11
is used in the molding step. Moreover, other speaker component is
obtained by using molding die 72 for other speaker component such
as a sub-cone in the molding step. Speaker 10, 10a, 10b is
configured using such speaker components, so that speaker 10, 10a,
10b having excellent external appearance in which the degree of
freedom in adjustment of characteristics and sound quality is
large, the humidity resistance reliability and strength are
improved, and the productivity is high is realized.
[0223] Fiber 63 may be natural fiber or chemical fiber. The natural
fiber used in fiber 63 may be bamboo fiber 17, wood pulp material,
or the like, because they are cellulose fibers. If bamboo fiber 17
is used for fiber 63, bamboo fiber 17 as described in Embodiments 1
to 3 may be used. If bamboo fiber 17 and fiber 18 are used for
fibers 63, 64, the speaker component such as diaphragm 1, frame 7,
and cap 11 will have characteristics of high elastic modulus and
high strength. Bamboo fiber 17 may be bamboo pulp. The chemical
fiber used in fiber 63 may be a carbon fiber, an aramid fiber, or
the like. The aramid fiber may be aramid pulp.
[0224] The fiber length of fiber 63 is preferably greater than or
equal to 0.2 mm and smaller than or equal to 3 mm. The effect of
heating granulation when obtaining compound 15 is efficiently
produced by including fiber 64 having a fiber length in a range of
greater than or equal to 0.2 mm and smaller than or equal to 3 mm
for compound 15. The productivity and the quality of the speaker
component such as diaphragm 1 are also improved.
[0225] If the fiber length of fiber 64 is shorter than 0.2 mm, the
effect of fiber 64 is not efficiently produced, and the speaker
component of high elastic modulus is hardly obtained. If, on the
other hand, the fiber length of fiber 64 is longer than 3 mm,
secondary aggregation that occurs from the entanglement between
fibers 64 easily occur, and dispersion failure of fiber 64 easily
occurs. Thus, a long time is required for the kneading of resin 62
and fiber 63. An aggregate of fiber 64 may appear on the surface of
the speaker component, thereby affecting the external appearance of
speaker 10, 10a, 10b. Therefore, the productivity and the quality
of the speaker component such as diaphragm 1 enhance if the fiber
length of fiber 64 to be mixed in compound 15 is within a range of
greater than or equal to 0.2 mm and smaller than or equal to 3
mm.
[0226] Resin 62 preferably uses a crystalline or non-crystalline
olefin resin. Satisfactory moldability of the speaker component
such as diaphragm 1 is realized by using the olefin resin for resin
62. The crystalline resin and/or the non-crystalline resin are used
depending on the application of resin 62. Thus, resin 62 satisfies
an optimum characteristic value for a resin material.
[0227] The PP is generally easily available, and is easily
injection molded. Furthermore, the speaker component having large
internal loss is obtained by using PP for resin 62. However, the
material of resin 62 is not limited to PP. The material of resin 62
may be appropriately selected such that a desired characteristic
value for the speaker component such as diaphragm 1 is
obtained.
[0228] An engineering plastic may be used for resin 62, not limited
to PP. The speaker component excellent in heat resistance or
solvent resistance is obtained by using the engineering plastic for
resin 62. The engineering plastic used in resin 62 may include
polyacetal, polyamide, polycarbonate,
polybutyleneterephthalate.
[0229] In view of environmental consideration, resin 62 may use a
biodegradable plastic typified by polylactic acid. An
environment-friendly speaker component having high performance that
does not require a special disposal method and that avoids extra
discharge of carbon dioxide in disposal is obtained by using a
biodegradable plastic for resin 62. Other than polylactic acid, the
biodegradable plastic may be polycaprolactam, modified polyvinyl
alcohol, casein plastics, and the like. The polylactic acid excels
in transparency and rigidity compared to other biodegradable
plastic. The polylactic acid also has satisfactory compatibility
with the cellulose contained in fiber 63, and thus easily fixes on
the surface of fiber 63. Thus, an environment-friendly speaker
component such as diaphragm 1 having high rigidity in which the
external appearance color of fiber 63 is not affected is obtained
by using polylactic acid for resin 62.
INDUSTRIAL APPLICABILITY
[0230] The speaker diaphragm, the speaker frame, the speaker dust
cap, the speaker, and the device according to the present invention
are applied to a video acoustic equipment that requires highly
accurate characteristic generation and sound generation or
electronic equipment such as information communication device, and
a moving body device such as an automobile.
* * * * *