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JP2015082744

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DESCRIPTION JP2015082744
An object of the present invention is to provide a loudspeaker which has excellent heat resistance
and high input resistance. A loudspeaker 11 includes a diaphragm 15, a frame 12, a magnetic
gap 13 formed between an opposing surface 14D and a side surface of a first plate 14C, a yoke
14A, an inner magnet 14B, and a first plate. A magnetic circuit 14 including an inner magnet 14B
and a voice coil 16 are included. The diaphragm 15 includes a main body portion 15A using a
thermoplastic resin, an edge portion 15B, and a fixing portion 15D. The edge portion 15B is
formed on the outer periphery of the main body portion 15A, the frame 12 is connected to the
outer peripheral portion of the diaphragm 15, the main body portion 15A is connected to the
frame 12 via the edge portion 15B, and the magnetic circuit 14 is Coupled to frame 12. The first
end of the voice coil 16 is connected to the back side of the diaphragm 15, and the second end of
the voice coil 16 is inserted into the magnetic gap 13. [Selected figure] Figure 3
Vibrator, loudspeaker, and electronic device using loudspeaker
[0001]
The present invention relates to a loudspeaker used for an electronic device such as a portable
device, a diaphragm used therefor, and an electronic device using the loudspeaker.
[0002]
Hereinafter, a conventional loudspeaker will be described.
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1
Conventional loudspeakers include a frame, a magnetic circuit including a magnetic gap, a
diaphragm and a voice coil. A magnetic circuit is coupled to the frame. The outer periphery of the
diaphragm is connected to the frame. The first end of the voice coil is coupled to the diaphragm.
On the other hand, the second end side of the voice coil is inserted in the magnetic gap.
[0003]
And a diaphragm contains a main-body part and an edge. The edge portion is formed on the
outer periphery of the main body portion. The main body portion is formed of a rigid resin. On
the other hand, the edge portion is formed of soft rubber. As the material of the edge portion, for
example, a polyolefin-based, polyurethane-based, or polystyrene-based elastomer material is
mainly used.
[0004]
As prior art document information related to the invention of this application, for example,
Patent Document 1 and Patent Document 2 are known.
[0005]
JP-A-7-131888 JP-A-2001-103595
[0006]
Elastomeric materials used for conventional edges have low heat resistance temperatures.
Therefore, when a large input signal is supplied to the loudspeaker, there is a problem that the
heat generated by the voice coil or the like reduces the reliability of the edge.
[0007]
Therefore, the present invention solves this problem, and provides a loudspeaker which is
excellent in heat resistance and highly resistant to input.
[0008]
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In order to solve the above-mentioned subject, a diaphragm of the present invention contains a
main part and an edge part.
The edge portion is provided on the outer periphery of the main body portion.
And a main-body part is formed of the 1st thermoplastic resin. The first thermoplastic resin
contains at least one of polyamide 6 and polyamide 66, and polypropylene. On the other hand,
the edge portion is formed of the second thermoplastic resin. The second thermoplastic resin
contains polypropylene and crosslinked ethylene propylene diene rubber. In the second
thermoplastic resin, polypropylene forms a sea structure, and cross-linked ethylene propylene
diene rubber forms an island structure. In this way, the intended purpose can be achieved.
[0009]
As described above, according to the present invention, the main body is formed of at least one of
polyamide 6 and polyamide 66 and a resin containing polypropylene. Therefore, the heat
resistance temperature of the main body is high, and the elastic modulus is large. On the other
hand, the edge portion is formed of a resin having a sea structure of polypropylene and an island
structure of crosslinked ethylene propylene diene rubber. Therefore, the hardness of the edge
portion is soft and the heat resistant temperature is high. Therefore, the loudspeaker can be
highly heat resistant and can have a large input resistance.
[0010]
BRIEF DESCRIPTION OF THE DRAWINGS The conceptual diagram of the electronic device of
embodiment of this invention. FIG. 1 is a top view of a loudspeaker according to an embodiment
of the present invention. FIG. 1 is a cross-sectional view of a loudspeaker according to an
embodiment of the present invention. The principal part expanded sectional view of the
diaphragm of an embodiment of the invention.
[0011]
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FIG. 1 is a conceptual view of the electronic device of the present embodiment. The electronic
device 51 includes a housing 52 having a hole 52A, an amplification unit 53, and a loudspeaker
11. The amplification unit 53 and the loudspeaker 11 are housed in a housing 52. The
amplification unit 53 is electrically connected to the loudspeaker 11. The amplification unit 53
may include a reproduction unit of a sound source. It is preferable to provide a waterproof sheet
55 between the inner surface of the housing 52 and the loudspeaker 11. This configuration
improves the waterproofness of the electronic device. The waterproof sheet 55 closes the hole
52A. The electronic device 51 may also include, for example, a display unit 54 such as a liquid
crystal display.
[0012]
Electronic device 51 is, for example, a smart phone. However, the electronic device 51 is not
limited to this, and may be, for example, a mobile device such as a mobile phone or a tablet
terminal, an audio device such as a mini component system, or a video device such as a
television.
[0013]
And in recent years, with the spread of such portable devices, the demand for reducing the size
of the loudspeaker 11 is increasing. Furthermore, these electronic devices 51 include a
communication unit for connecting to the Internet. Then, the electronic device 51 is connected to
the Wifi and the communication line, and receives the moving image and the like distributed by
the Internet through the line. Then, the electronic device 51 can display the moving image on the
display unit for viewing. Therefore, these electronic devices 51 are required to be able to
reproduce powerful sound. Therefore, the small-sized loudspeaker 11 used for such an electronic
device 51 is required to reproduce excellent sound quality, and in particular, reproduction of a
bass range and high input resistance are required.
[0014]
Hereinafter, the loudspeaker 11 using the diaphragm of the present embodiment will be
described with reference to the drawings. FIG. 2 is a top view of the loudspeaker 11 in the
present embodiment. FIG. 3 is a cross-sectional view of the loudspeaker according to the present
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embodiment. In addition, FIG. 2 has shown the cross section at the time of cut ¦ disconnecting a
loudspeaker by section line 3-3 in FIG.
[0015]
The loudspeaker 11 includes a diaphragm 15, a frame 12, a magnetic circuit 14 including a
magnetic gap 13, and a voice coil 16. The diaphragm 15 includes a main body 15A and an edge
15B. The edge portion 15B is formed on the outer periphery of the main body portion 15A. The
frame 12 is connected to the outer peripheral portion of the diaphragm 15. That is, the main
body portion 15A is connected to the frame 12 through the edge portion 15B. The magnetic
circuit 14 is coupled to the frame 12. The magnetic circuit 14 is preferably housed in the frame
12. The first end of the voice coil 16 is connected to the back side of the diaphragm 15. On the
other hand, the second end of the voice coil 16 is inserted into the magnetic gap 13.
[0016]
The magnetic circuit 14 is preferably of the internal magnet type. With this configuration, the
loudspeaker 11 can be made smaller. When the magnetic circuit 14 is an internal magnet type,
the magnetic circuit 14 preferably includes a yoke 14A, an inner magnet 14B, and a first plate
14C. In this case, the yoke 14A includes the opposing surface 14D with the side surface of the
first plate 14C. The magnetic circuit 14 includes a magnetic gap 13 formed between the facing
surface 14D and the side surface of the first plate 14C.
[0017]
In addition, although the magnetic circuit 14 of this example is an internal magnet type, it is not
restricted to this. The magnetic circuit 14 may be of the inside and outside magnet type. In this
case, the yoke 14A is preferably a flat plate. Then, a pair of outer magnets are mounted on the
yoke 14A so as to sandwich the inner magnet 14B. The magnetic poles of the outer magnets are
arranged to face in the opposite direction to the magnetic poles of the inner magnets 14B.
Preferably, a second plate is provided on the upper surface of the outer magnet. In this case, the
side surface of the first plate 14C opposes the side surface of the second plate, and the magnetic
gap 13 is formed between the side surface of the first plate 14C and the side surface of the
second plate. With this configuration, the magnetic flux density in the magnetic gap 13 can be
increased. Therefore, the sound pressure of the sound output from the loudspeaker 11 can be
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increased. With this configuration, the loudspeaker 11 can be made smaller.
[0018]
Next, the diaphragm 15 will be described in detail. As a material of the main body portion 15A, it
is preferable to use the first thermoplastic resin 35. The first thermoplastic resin 35 contains
polypropylene. Furthermore, the first thermoplastic resin 35 contains at least one of polyamide 6
and polyamide 66. The main component of the first thermoplastic resin 35 is a mixture of at least
one of polyamide 6 and polyamide 66 and polypropylene.
[0019]
With the above configuration, the main body portion 15A contains polypropylene, so the value of
the internal loss can be increased. Furthermore, since the first thermoplastic resin 35 contains at
least one of the polyamide 6 and the polyamide 66, the heat resistance temperature of the main
portion 15A is improved. The main body 15A can be manufactured by injection molding or the
like. Therefore, the productivity of the main body 15A is excellent.
[0020]
Generally, a mixture of polypropylene and polyamides is often tested as a measure to improve
the heat resistance of polypropylene. However, except for some polyamides such as polyamide
12, it is difficult to mix polypropylene and polyamide. Therefore, it is preferable that the first
thermoplastic resin 35 further contain a compatibilizer. The compatibilizer preferably has a
reactive group that reacts with the polyamide. As a reactive group which reacts with the
polyamide, for example, a carboxylic acid group, an acid anhydride group, an epoxy group, an
amino group and an isocyanate group can be used. This configuration improves the binding
strength between polypropylene and polyamide. Therefore, the elastic modulus of the diaphragm
15 is improved.
[0021]
As the compatibilizer, for example, modified polyolefin can be used. In this case, it is preferable
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to substitute the terminal etc. of the polyolefin with a reactive group that reacts with the
polyamide.
[0022]
Alternatively, as the compatibilizer, a block copolymer having a polyolefin block and an ester
block may be used. By this configuration, the dispersion state of polypropylene and polyamide is
improved, so the elastic modulus of the diaphragm 15 is improved.
[0023]
FIG. 4 is an enlarged cross-sectional view of the main part of the diaphragm 15. The edge portion
15B preferably includes a joint portion 15C, a fixing portion 15D, and a roll portion 15E. The
coupling portion 15C is provided on the inner circumferential portion of the edge portion 15B.
And, the joint 15C is joined to the main body 15A. On the other hand, the fixing portion 15D is
formed on the outer peripheral portion of the edge portion 15B. The fixing portion 15D is fixed
to the frame 12 shown in FIG. The roll unit 15E couples the coupling unit 15C and the fixing unit
15D. The shape of the roll unit 15E may be, for example, an arc shape.
[0024]
And the diaphragm 15 of the above structure is mounted ¦ worn with the flame ¦ frame 12 in the
direction which the roll part 15E protrudes on the front side of the loudspeaker 11, as shown in
FIG.
[0025]
In addition, it is preferable to provide the corrugation 15F in the roll part 15E.
The corrugation 15F protrudes, for example, on the back side of the diaphragm 15. The roll
portion 15E has a very complicated shape because the corrugation 15F is provided. Therefore,
the edge portion 15B is manufactured by injection molding a second thermoplastic resin.
Therefore, the corrugation 15F of complicated shape can be provided to the edge portion 15B.
Also, the productivity of the edge portion 15B is excellent.
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[0026]
Next, the material of the edge portion 15B will be described in detail. When a large input signal is
input to the loudspeaker 11 shown in FIG. 3, the heat generation in the loudspeaker 11
increases. The portable device as shown in FIG. 1 has a sealed structure for waterproofing and
the like. Therefore, it is difficult to dissipate the heat generated in the portable device to the
outside. However, the material of the edge used for the conventional loudspeaker selects the
elastomer material in favor of softness and lightness. Therefore, there is a possibility that the
temperature of the edge portion used for the conventional speaker may rise to the heat-resistant
temperature of the material or more.
[0027]
Therefore, in addition to the requirement of mechanical properties such as low hardness, the
material of the edge portion 15B of the present embodiment is also required to have a high heat
resistant temperature. The diaphragm 15 solves this problem, and provides a loudspeaker 11
with excellent heat resistance and high input resistance. For this purpose, the edge portion 15B is
formed of the second thermoplastic resin 36 containing polypropylene and ethylene propylene
diene rubber. In addition, by forming a crosslinked ethylene propylene diene rubber into an
island structure using polypropylene as a matrix, good moldability (flowability) can be obtained,
and thin-wall molding of 0.2 mm or less is possible.
[0028]
By the above configuration, the hardness of the edge portion 15B can be reduced. The hardness
of the edge portion 15B shown in FIG. 3 can be further lowered as compared with the case where
CTBN or the like is used for the epoxy resin. For example, the hardness of the edge portion 15B
can be set to A30 ° or more and A60 ° or less. The hardness value is measured using a
durometer type A in accordance with the standard of ISO 7619-1. Thus, since the edge portion
15B is soft, f0 of the diaphragm 15 can be further lowered. Furthermore, since the heat
resistance of the edge portion 15B is further excellent, the input resistance of the loudspeaker 11
can be further increased. Furthermore, the edge portion 15B is less deteriorated in
characteristics even under an environment of, for example, about 120.degree.
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[0029]
Moreover, the tensile elasticity modulus at normal temperature (20 degreeC) of edge part 15B is
1 Mpa or more and 20 Mpa or less. And the tensile elasticity modulus at 150 degrees C of edge
part 15B is 50 Kpa or more and 100 KPa or less. Therefore, the value of the elastic modulus of
the edge portion 15B is less dependent on temperature as compared with other general
thermoplastic elastomers. Therefore, the sound quality reproduced by the loudspeaker 11 is very
excellent even in a high temperature environment. In addition, the value of a tensile elasticity
modulus uses the Vibron-type viscoelasticity measuring apparatus (DMA). The measurement of
tensile modulus is a value of storage modulus when 5% of strain is repeatedly generated at a
frequency of 1 Hz.
[0030]
Further, since both the main body portion 15A and the edge portion 15B are formed of a
thermoplastic material, the main body portion 15A and the edge portion 15B shown in FIG. 3 can
be formed by injection molding or the like. Therefore, it is preferable that the main body portion
15A, the edge portion, and the edge portion 15B be a two-color molded body 15G formed by
two-color molding. By this configuration, it is possible to reduce the number of steps of
manufacturing the diaphragm 15. Further, since the second thermoplastic resin 36 has a high
melting point and thermal decomposition temperature, the temperature of the second
thermoplastic resin 36 can be increased at the time of resin molding. Therefore, when the main
body portion 15A and the edge portion 15B are formed by two-color molding, the first
thermoplastic resin 35 of the main body portion 15A is melted. That is, in a state where the first
thermoplastic resin 35 is melted at the interface with the edge portion 15B in the main body
portion 15A, the first thermoplastic resin 35 contacts the second thermoplastic resin 36 in the
molten state. Then, by cooling the second thermoplastic resin 36 in that state, the first
thermoplastic resin 35 is also cured, and the main body portion 15A and the edge portion 15B
are firmly adhered.
[0031]
In general, the temperature of the diaphragm 15 reaches up to about 160.degree. Therefore, the
melting point of the first thermoplastic resin 35 is preferably 170 ° C. or more. This
configuration can suppress melting of the main body 15A due to heat.
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[0032]
The main body portion 15A is preferably light. Then, it is preferable that the thickness of 15 A of
main-body parts is 0.1 mm or more and 0.5 mm or less, for example. On the other hand, it is
preferable that the thickness of edge part 15B is 0.03 mm or more and 0.2 mm or less, for
example. With this configuration, the weight of the diaphragm 15 can be reduced, so that the
sound pressure frequency characteristics of the loudspeaker 11 are excellent.
[0033]
As described above, the main body portion 15A and the edge portion 15B are light and extremely
thin. When molding the thin diaphragm 15 in this manner by injection molding, it is preferable to
increase the molding temperature to improve the flowability of the resin. Therefore, when the
second thermoplastic resin 36 reaches the interface with the main body 15A, the temperature of
the second thermoplastic resin 36 needs to be higher than the melting point (or glass transition
temperature) of the first thermoplastic resin 35. There is. Therefore, it is preferable that the
temperature of the second thermoplastic resin 36 when molding the edge portion 15B be higher
by about 30 ° C. to 80 ° C. than the melting point of the first thermoplastic resin 35, for
example.
[0034]
However, when a general thermoplastic low hardness elastomer is used for the edge portion 15B,
when the molding temperature exceeds 230 ° C., the general thermoplastic low hardness
elastomer rapidly begins to be decomposed. Accordingly, when a general thermoplastic low
hardness elastomer is used for the edge portion 15B, the molding temperature is preferably less
than 230.degree. However, if the molding temperature of the edge portion 15B is less than 230
° C., the first thermoplastic resin 35 is not melted. Accordingly, the fusion strength between the
edge portion 15B and the main portion 15A is reduced.
[0035]
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Therefore, the edge portion 15B is formed of the second thermoplastic resin 36 including
polypropylene (sea) and cross-linked ethylene propylene diene rubber (island). The second
thermoplastic resin 36 has less thermal decomposition even at a temperature of 230 ° C. or
higher. Therefore, the molding temperature of the edge portion 15B can be increased. Therefore,
when the second thermoplastic resin 36 in the molten state reaches the interface with the main
body 15A at the time of molding and contacts the main body 15A, the heat of the second
thermoplastic resin 36 causes the first thermoplastic resin 35 to Let it melt. By this
configuration, the adhesive strength between the main body portion 15A and the edge portion
15B is improved. The second thermoplastic resin 36 can be molded at 250 ° C. to 280 ° C.
Therefore, when the main body portion 15A and the edge portion 15B are molded by two-color
molding, the number of steps of the molding process can be reduced.
[0036]
When the second thermoplastic resin 36 is exposed to a temperature of 260 ° C. for one hour, it
is preferable that the material has a heat loss of 5% or more and 25% or less of the organic
component excluding the inorganic filler. By this configuration, the edge portion 15B can be
molded at a temperature of about 280.degree. Furthermore, the thermal decomposition of the
second thermoplastic resin 36 due to the temperature at the time of molding can be suppressed.
[0037]
The edge portion 15B preferably contains an additive and an inorganic filler. The additive and
the inorganic filler are not particularly limited, but talc and silicon oxide are preferably used. Talc
and silicon oxide have a small particle size, so the diaphragm 15 can be made thin. In addition,
known additives and inorganic fillers can be added to the main body portion 15A. Moreover, you
may mix and use those well-known additives and inorganic fillers suitably.
[0038]
When the loudspeaker 11 as described above is mounted on the electronic device 51 shown in
FIG. 1, since the heat resistance of the loudspeaker 11 is high, the loudspeaker 11 reproduces
even if the temperature in the housing 52 rises. Deterioration of sound quality can be
suppressed. Therefore, the electronic components constituting the electronic device 51 can be
arranged at high density, so the electronic device 51 can be made smaller.
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[0039]
The diaphragm according to the present invention has the effect of being excellent in heat
resistance, and is particularly useful when used for a loudspeaker or the like used in electronic
devices such as portable devices.
[0040]
11 Loudspeaker 12 Frame 13 Magnetic gap 14 Magnetic circuit 14A Yoke 14B Inner magnet
14C First plate 14D Opposite surface 15 Diaphragm 15A Body 15B Edge 15C Coupling 15D
Fixing 15E Roll 15F Corrugation 15G Two-color molded body 16 voice Coil 35 first thermoplastic
resin 36 second thermoplastic resin 51 electronic device 52 housing 52A hole 53 amplification
unit 54 display unit 55 waterproof sheet
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