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JPH07298392

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Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
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DESCRIPTION JPH07298392
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
loudspeaker for use in a large input sound reproducing apparatus.
[0002]
2. Description of the Related Art In recent years, in a concert hall or an outdoor sound
reproducing system, a sound reproducing apparatus for reproducing a large volume by means of
an electrical auxiliary means is used. There are many speaker structures as shown in FIG. 16,
including those used in sound reproducing apparatuses for such applications. Here, a general
conventional speaker 1 will be described with reference to FIG.
[0003]
FIG. 16 is a half sectional view showing the structure of the speaker 1. An annular magnetic
circuit 6 including a center pole 3, a magnet 4, and a top plate 5 is formed at the lower end of the
annular frame 2 in this figure. A magnetic flux of high density is formed in the annular gap 7 of
the upper outer peripheral portion of the center pole 3 and the inner peripheral portion of the
top plate 5, and the voice coil bobbin 8 is held so as to be vertically movable.
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[0004]
The voice coil bobbin 8 is generally a member obtained by forming thin paper into a cylindrical
shape, and a coil 9 is wound around the outer periphery of the lower end portion. The coil 9
generates an electromagnetic force to cause the voice coil bobbin 8 to move in a piston when an
acoustic drive current is applied, and is made of, for example, a wire made of aluminum or
copper. A reinforcing paper 10 is wound around the outer periphery of the voice coil bobbin 8
except for the lower end thereof to secure the rigidity of the voice coil bobbin. The diaphragm 11
and the suspension 12 are fixed to such a voice coil bobbin 8. The diaphragm 11 is attached to
the frame 2 via the edge 13, and the suspension 12 is directly attached to the frame 2 and held
so as to be able to vibrate.
[0005]
In the speaker 1 configured as described above, when an acoustic drive current is input to the
coil 9, an electromagnetic force is generated by the drive current and the magnetic flux of the air
gap 7, and the diaphragm 11 held by the suspension 12 and the edge 13 Vibrates and outputs a
sound.
[0006]
However, in the conventional speaker 1 shown in FIG. 16, the drive current of the coil 9 at the
time of outputting high-power sound is large, and the Joule heat generated by this current is also
large.
Therefore, there is a problem that the voice coil bobbin 8 including the coil 9 generates heat.
These elevated temperatures are proportional to the driving power, but the insulating layer of the
coil 9 is thermally destroyed by such a rise in temperature to cause insulation failure or the
adhesion between the coil windings is reduced, so that the coil 9 is damaged. There was also a
problem of Furthermore, when driving with large power for a long time, there is also a problem
that the heat of the coil 9 is transmitted to the suspension 12 and the diaphragm 11, and the
suspension 12 and the diaphragm 11 may be ignited.
[0007]
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The present invention has been made in view of such conventional problems, and it is an object
of the present invention to prevent the performance of a speaker from being deteriorated due to
the temperature rise of the voice coil of the speaker. In particular, the inventions of claims 1 to 7
aim to realize a speaker capable of continuously outputting a high output sound with a larger
drive power by cooling a voice coil of the speaker.
[0008]
The inventions of claims 8 and 9 aim to prevent a voice coil from being damaged when driving
power is large and to realize a speaker that can be easily reproduced and repaired. A further
object of the present invention is to realize a speaker that prevents the ignition of a suspension
that holds a voice coil bobbin and prevents a fire in advance.
[0009]
The invention according to claim 1 of the present application relates to a diaphragm for giving
air vibration, a cylindrical voice coil bobbin joined to the diaphragm, a coil wound around the
voice coil bobbin, and an outer periphery of the voice coil bobbin. A speaker having an annular
top plate located at the center and a center pole inserted inside the voice coil bobbin, wherein the
voice coil bobbin is a sheet-like core material in which metal fine wires coated with an insulating
material are arranged in parallel And a surface member made of a glass fiber reinforced plastic
sheet adhered to both surfaces of the core material, and formed in a cylindrical shape as a
composite member sheet in which the core material and the surface material are integrated; The
present invention is characterized in that the conductor is fixed by winding to a single layer or a
plurality of layers on the outer peripheral surface of the voice coil bobbin.
[0010]
The invention according to claim 2 of the present application is a diaphragm for giving air
vibration, a cylindrical voice coil bobbin joined to the diaphragm, a coil wound around the voice
coil bobbin, and an annular top plate located on the outer periphery of the voice coil bobbin A
speaker having a center pole inserted into the inside of a voice coil bobbin, wherein the voice coil
bobbin is adhered to both sides of a sheet-like core material in which metal fine wires coated
with an insulating material are arranged in parallel, and both surfaces of the core material A
composite member sheet having a surface material composed of a glass fiber reinforced plastic
sheet, wherein the surface material is integrally bonded to a part of the core material, and the
coil is a voice coil bobbin The conductor is wound and fixed to a single layer or a plurality of
layers on the exposed portion of the core material in the outer peripheral surface of the above.
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[0011]
According to the invention of claim 3 of the present application, a diaphragm for giving air
vibration, a cylindrical voice coil bobbin joined to the diaphragm, a dust cap covering an end face
of the voice coil bobbin, a coil wound around the voice coil bobbin, and an outer periphery of the
voice coil bobbin A speaker having an annular top plate located at the center and a center pole
inserted inside the voice coil bobbin, wherein the voice coil bobbin is a sheet-like core material in
which metal fine wires coated with an insulating material are arranged in parallel And a surface
member made of a glass fiber reinforced plastic sheet bonded to both sides of the core material,
and a composite member sheet in which the surface material is integrally bonded to a part of the
core material is formed in a cylindrical shape In the coil, the conductor is wound and fixed to a
single layer or a plurality of layers on the exposed portion of the core material on the lower end
outer peripheral surface of the voice coil bobbin. , And the dust cap is characterized in that it is
the exposed portion of the core material of the upper outer peripheral surface of the voice coil
bobbin as mounting a substantially spherical shell shape is as a bonding surface.
[0012]
In the invention of claim 4 of the present application, the dust cap is characterized in that a heat
sink is provided on the substantially spherical shell-like surface.
[0013]
The invention according to claim 5 of the present application is a diaphragm for giving air
vibration, a cylindrical voice coil bobbin joined to the diaphragm, a coil wound around the voice
coil bobbin, an annular top plate located on the outer periphery of the voice coil bobbin A
speaker having a center pole inserted into the inside of a voice coil bobbin, which is integrally
formed with a recess and a recess that abuts the outer periphery of the coil and has a plurality of
projections formed with a plurality of cooling fins for dissipating heat conducted from the coil.
And a cooling member closely attached to the winding outer peripheral surface of the coil and
the outer peripheral surface of the voice coil bobbin, and the top plate is provided with a cutaway
portion at an inner peripheral portion for providing a space for vibrating the cooling member. It
is characterized by
[0014]
The invention according to claim 6 of the present application is a diaphragm for giving air
vibration, a cylindrical voice coil bobbin joined to the diaphragm, a coil wound around the voice
coil bobbin, and an annular top plate located on the outer periphery of the voice coil bobbin It is
a speaker which has a center pole inserted in the inside of a voice coil bobbin, and a voice coil
bobbin is what a linear projection part was spirally formed in a part of perimeter part of a voice
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coil bobbin, and a coil is a wire The present invention is characterized in that the conductor is
wound and fixed to a single layer or a plurality of layers on the outer peripheral surface of the
voice coil bobbin in which the protrusion portion is not formed.
[0015]
The invention according to claim 7 of the present application is a diaphragm for giving air
vibration, a cylindrical voice coil bobbin joined to the diaphragm, a coil wound around the voice
coil bobbin, and an annular top plate located on the outer periphery of the voice coil bobbin A
speaker having a center pole inserted inside the voice coil bobbin, wherein the top plate has a
plurality of radially extending through holes of a thin tube penetrating from the outer peripheral
surface to the inner peripheral surface inside the annular magnetic band An annular hollow
member having an annular slit communicating with the through hole and an air vent for
supplying air to the slit is provided on the outer peripheral portion of the top plate.
[0016]
The invention according to claim 8 of the present application is a diaphragm for giving air
vibration, a cylindrical voice coil bobbin joined to the diaphragm, a coil wound around the voice
coil bobbin, and an annular top plate located on the outer periphery of the voice coil bobbin A
speaker having a center pole inserted inside the voice coil bobbin, wherein an overcurrent
protection element having a resistance value larger than that of a conductor portion of the coil is
provided in series with the coil via a terminal on the outer periphery of the voice coil bobbin. It is
a feature.
[0017]
The invention according to claim 9 of the present application is a diaphragm for giving air
vibration, a cylindrical voice coil bobbin joined to the diaphragm, a coil wound around the voice
coil bobbin, and an annular top plate located on the outer periphery of the voice coil bobbin A
speaker having a center pole inserted into the inside of a voice coil bobbin, characterized in that
a thermal fuse which is fused by a temperature rise through a terminal is provided in series with
a coil on the outer peripheral portion of the voice coil bobbin.
[0018]
The invention according to claim 10 of the present application is a diaphragm for giving air
vibration, a cylindrical voice coil bobbin joined to the diaphragm, a suspension for holding the
voice coil bobbin in a vibrating manner, a coil wound around the voice coil bobbin, and a voice
coil bobbin. A speaker having an annular top plate located at an outer peripheral portion and a
center pole inserted inside a voice coil bobbin, wherein the voice coil bobbin, the diaphragm and
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the suspension are bonded using a self-extinguishing adhesive layer It is characterized by
[0019]
According to the invention of claim 1 of the present application having such a feature, when a
drive current is applied to the coil wound around the voice coil bobbin, the coil receives an
electromagnetic force and the diaphragm is integrated with the voice coil bobbin. To vibrate.
At that time, the heat generated by the coil is conducted to the core material.
Since the core material is formed in a sheet shape in which fine metal wires are arranged in
parallel, heat is dissipated to the entire voice coil bobbin through the core material.
[0020]
Further, according to the second aspect of the present invention, in addition to the function of
the first aspect, since the surface material is removed at the portion where the coil is fixed to the
winding, the heat of the coil is conducted directly to the core material.
[0021]
Further, according to the third and fourth inventions of the present application, in addition to the
function of the second invention, the heat generated in the coil is also conducted to the dust cap,
whereby the heat is dissipated into the air.
[0022]
According to the invention of claim 5 of the present application, Joule heat of the coil is
dissipated from the cooling member into the air.
[0023]
Further, according to the sixth aspect of the present invention, an air flow is generated along
with the vertical vibration of the voice coil bobbin, and the heat of the voice coil bobbin is
diffused.
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[0024]
According to the seventh aspect of the present invention, the cooling air is forcibly fed to the coil
through the hollow member and the through hole.
[0025]
Further, according to the invention of claim 8 of the present application, when an overcurrent
flows in the coil, the overcurrent protection element is melted and the voice coil bobbin is
prevented from being overheated.
[0026]
Moreover, according to the invention of claim 9 of the present application, the thermal fuse is
melted before the coil generates heat, and the voice coil bobbin is prevented from being
overheated.
[0027]
Furthermore, according to the invention of claim 10 of the present application, the selfextinguishing agent contained in the adhesive layer prevents the ignition even when the vicinity
of the diaphragm or the suspension reaches the ignition point due to the temperature rise of the
coil.
[0028]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The loudspeakers according to
the embodiments of the present invention will be described below with reference to the
drawings, focusing on the structure of the voice coil unit.
In the drawings of this embodiment, the same parts as those of the conventional example are
given the same reference numerals and the description thereof is omitted.
[0029]
FIG. 1 is a partially cutaway perspective view showing the structure of a voice coil unit 21 used
for a speaker 20 according to a first embodiment of the present invention.
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As shown in the figure, the voice coil portion 21 is formed by winding a coil 9 around the lower
end portion of a cylindrical voice coil bobbin 22.
As shown in FIG. 2A, the voice coil bobbin 22 is formed of a composite member sheet 23 as a
hobin material, which is formed into a cylindrical shape.
As shown in FIG. 2B, the composite member sheet 23 is, for example, made of glass fiber
reinforced polyimide as the surface members 23a and 23b, and core members 23c bonded from
both surfaces by the surface members 23a and 23b.
[0030]
As shown in FIG. 2C, the core member 23c is a sheet-like member in which fine wires 24 of high
thermal conductivity such as aluminum or copper are coated with an insulating varnish, and
many fine wires 24 are arranged in parallel by adhesion.
Such a member is formed into a sandwich structure to form a composite member sheet 23.
The composite member sheet 23 is formed in a cylindrical shape as shown in FIG.
Next, the coil 9 made of copper or aluminum wire is fixedly wound in a single layer or multiple
layers on the lower outer peripheral portion of the voice coil bobbin 22.
[0031]
The operation of the speaker 20 having the voice coil unit 21 having such a structure will be
described.
When a drive current flows through the coil 9, Joule heat is generated due to the resistance of
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the wire of the coil 9, and the temperature of the coil 9 itself rises.
The heat generated by the coil 9 is transmitted to the core material 23c through the surface
materials 23a and 23b.
The core material 23 c is formed by arranging a large number of metal fine wires 24 having high
thermal conductivity in parallel, and thus the generated heat is easily transmitted to the entire
voice coil bobbin 22.
[0032]
Therefore, as compared with the case where the heat is diffused from the coil 9 alone into the
surrounding air by radiation or convection as in the voice coil bobbin 8 shown in FIG. .
Therefore, the temperature rise of the coil 9 is suppressed to a small extent.
In addition, since the voice coil bobbin 22 has a sandwich structure, it has a light weight and high
rigidity, and also has an effect of being resistant to mechanical buckling which tends to occur
with piston vibration.
Furthermore, since the core material 23c is a metal coated with an insulating varnish, no
conductor path of eddy current is formed as compared to the case where a continuous metal foil
is used as the core material 23c.
Therefore, no eddy current is generated in the core 23c, and no secondary heat generation
occurs.
[0033]
Next, a speaker according to a second embodiment of the present invention will be described
with reference to FIG. 3 and FIG.
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FIG. 3 is a half sectional view showing the structure of the speaker 30 of the second embodiment,
and FIG. 4 shows the structure of the composite member sheet 33 used for the speaker 30. As
shown in FIG.
In FIG. 4, the composite member sheet 33 is composed of surface materials 23a and 23b and a
core material 23c, as in the case shown in FIG. 2 (b). However, unlike the composite member
sheet 33 shown in FIG. 2A, the surface material 23a at the lower end portion is removed at a
constant width.
[0034]
Such a composite member sheet 33 is formed in a cylindrical shape, and is used as a voice coil
bobbin 32. Then, the coil 9 is fixedly wound in a single layer or a plurality of layers in the portion
from which the surface material 23a is removed. As a result, as shown in FIG. 3, the core material
23c and the coil 9 come into contact with each other. The voice coil portion 31 configured in this
manner is fixed to the suspension 12 and the diaphragm 11, and the diaphragm 13 is held by the
edge 13 so as to be able to vibrate on the frame 2. The coil 9 is held in the air gap 7 of the
annular magnetic circuit 6 formed of the magnet 4, the top plate 5 and the center pole 3.
[0035]
In the speaker 30 thus configured, when a drive current is applied to the coil 9, an
electromagnetic force is generated by the magnetic flux of the air gap 7 and the drive current of
the coil 9, and the diaphragm 11 performs a piston movement. The Joule heat generated by the
coil 9 is directly conducted to the metal core 23c, so the cooling effect of the voice coil bobbin 32
is further enhanced.
[0036]
Next, a loudspeaker according to a third embodiment of the present invention will be described
with reference to FIG. FIG. 5A is a half sectional view showing the structure of the speaker 40 of
the third embodiment. In this figure, the voice coil bobbin 42 of the voice coil portion 41 is
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formed of the same composite member sheet 33 as in the second embodiment, and the surface
material 23a is removed with a constant width at the lower end outer peripheral portion.
However, unlike the one shown in FIG. 4, the surface material 23 a is also removed in a strip
shape at the upper outer peripheral portion of the composite member sheet 33. Such a
composite member sheet 33 is formed in a cylindrical shape to form a voice coil bobbin 42. The
coil 9 is fixed in a single layer or a plurality of layers to the lower end portion from which the
surface material 23a is removed.
[0037]
A hemispherical shell shaped dust cap 43 is attached to the upper end of the voice coil bobbin
42. FIG. 5 (b) is a cross-sectional view of the dust cap 43, and a fold 43a is formed on the surface
of the spherical shell. The material of the dust cap 43 is a metal having a high thermal
conductivity such as aluminum or silver. As a result, the core 23c with high thermal conductivity
in the voice coil bobbin 42 and the dust cap 43 are directly joined. The suspension 12 and the
diaphragm 11 are attached to the voice coil unit 41 configured as described above, and the
diaphragm 11 is held so as to be vibrated with respect to the frame 2.
[0038]
In such a speaker 40, when a drive current flows through the coil 9, Joule heat is generated due
to the resistance of the coil 9, and the temperature of the coil 9 rises. The heat generated by the
coil 9 is transmitted to the core 23c in the lower layer. Since the core material 23 c is a metal
having high thermal conductivity, the heat is easily transmitted to the entire voice coil bobbin 42.
Further, the heat is conducted to the dust cap 43 connected to the voice coil bobbin 42 and
dissipated into the air through the fold 43a. Thus, the heat radiation effect is further enhanced
compared to the voice coil bobbins of the first and second embodiments. Even if the dust cap 43
is not provided with the fold 43a, the heat radiation effect of the voice coil bobbin 42 is not
significantly reduced.
[0039]
Next, a loudspeaker according to a fourth embodiment of the present invention will be described
with reference to FIG. 6 and FIG. FIG. 6 (a) is a partial external view of the voice coil unit 51 used
in the speaker of the fourth embodiment, and FIG. 6 (b) is a cross-sectional view thereof. In FIGS.
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6A and 6B, the voice coil bobbin 52 is a cylindrical member formed of a single-layer or two-layer
sheet as in the prior art. A drive coil 9 is wound around the outer periphery of the lower end
portion of the voice coil bobbin 52. A plurality of cooling members 53 are attached to the outer
peripheral portion of the voice coil bobbin 52 including the coil 9.
[0040]
The cooling member 53 is a strip-shaped member as shown in FIG. 6A, and is made of, for
example, a lightweight metal such as aluminum or titanium having a high thermal conductivity.
The cooling member 53 is integrally formed with a recessed portion 53a whose cross section has
a circular arc shape so as to be in close contact with the outer peripheral portion of the coil 9,
and a projected portion 53b having a radiation fin formed in a tree shape upward from the
recessed portion 53a. is there. For example, four such cooling members 53 are fixed to the outer
periphery of the voice coil bobbin 52 at equal intervals.
[0041]
On the other hand, as shown in FIG. 7, notches 54 are formed at, for example, four places in the
inner peripheral portion of the top plate 5. The notch portion 54 provides a vibration space of
the cooling member 53, and is provided at the same position as the mounting position of the
cooling member 53. The groove width of the notch portion 54 is set to be small so as not to
contact the cooling member, and constitutes the air gap 7 of the annular magnetic circuit 6
together with the other inner peripheral portion of the top plate 5. The voice coil unit 51
configured in this way is held on the frame by an edge and a suspension (not shown) as in the
other embodiments.
[0042]
In such a speaker, when a drive current is applied to the voice coil 9, Joule heat is generated due
to the resistance of the coil 9, and the temperature of the coil 9 rises. The heat generated by the
coil 9 is transmitted to the cooling member 53. Since the cooling member is made of metal
having high thermal conductivity and its surface area is large, the conducted heat is dissipated
into the air more quickly along with the vibration of the voice coil portion 51. Thus, the heat
dissipation effect is further enhanced. In addition, since the notch volume of the notch part 54 is
small compared with the space of the space | gap 7, the fall of the magnetic flux density in the
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cyclic | annular magnetic circuit 6 also hardly occurs. Therefore, large input sound reproduction
can be performed without lowering the efficiency.
[0043]
Next, a loudspeaker according to a fifth embodiment of the present invention will be described
with reference to FIG. 8 and FIG. FIG. 8 is a perspective view of the voice coil unit 61 used for the
speaker of the fifth embodiment, and FIG. 9 is a cross-sectional view thereof. As shown in FIGS. 8
and 9, the voice coil bobbin 62 has a sheet-like member formed in a cylindrical shape, and at the
same time, a helical linear protrusion 63 is integrally formed along the outer peripheral portion
of the cylinder. As shown in FIG. 9, the linear protrusion 63 is embossed so that the cross section
thereof has an arc shape on the outside. Such a linear projection 63 is formed only on the upper
portion of the voice coil bobbin 62, and the coil 9 is wound around the lower end outer
peripheral portion in the same manner as in the prior art.
[0044]
In the speaker having the voice coil portion 61 configured as described above, when a drive
current is applied to the coil 9, air is taken in from the upper end portion of the voice coil bobbin
62 by the piston motion of the diaphragm and the voice coil portion 61. This air flows along the
linear projections 63. The linear protrusions 63 are continuously and spirally formed to the
upper end of the voice coil bobbin 62, and the air flow advances downward while drawing a
vortex along the voice coil bobbin 62. The air flow cools the coil 9. Furthermore, since the linear
protrusions 62 are formed spirally along the cylinder of the voice coil bobbin 62 and in a
direction perpendicular to the vibration direction, the linear protrusions 62 act to resist the
vibration of the voice coil bobbin 62. Therefore, the air in the vicinity of the coil 9 is disturbed
and easily replaced with the air around the speaker, and the cooling effect is enhanced.
[0045]
Next, a loudspeaker according to a sixth embodiment of the present invention will be described
with reference to FIGS. FIG. 10 is a half sectional view showing the structure of the speaker 70 of
the sixth embodiment, and FIG. 11 is a perspective view showing the internal structure of the top
plate. As shown in FIG. 10, the voice coil portion 71 is formed by winding the coil 9 around a
cylindrical voice coil bobbin 72 in the same manner as in the conventional example, and can
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freely vibrate via the coil 9 in the air gap 7 of the annular magnetic circuit 6. It is held.
[0046]
A plurality of through holes 73 a are formed inside the top plate 73 facing the center pole 3 via
the air gap 7, and a hollow member 74 is attached to the outer peripheral portion. As shown in
FIG. 11, the through holes 73a are formed radially from the side wall of the annular top plate
toward the center thereof. FIG. 12 is an explanatory view of the hollow member 74 and the
attached state of the pipe 75 and the blower 76 connected thereto. As shown in the drawing, the
hollow member 74 is formed by processing a member having a vent hole 74a having a
rectangular cross section into an annular shape, and a slit 74b is formed on the inner peripheral
surface thereof. As shown in FIG. 10, the slits 74b and the through holes 73a communicate with
each other, and air is supplied to all the through holes 73a. As shown in FIG. 12, a
communication hole 74 c is formed in a part of the outer periphery of the hollow member 74,
and is connected to the blower 76 through a pipe 75.
[0047]
In the speaker 70 configured as described above, when the voice coil unit 71 is driven by the
drive current of the coil 9, the blower 76 supplies cooling air. That is, the air sent from the
blower 76 is supplied to the hollow member 74 through the pipe 75 and the communication hole
74c. The air that has flowed into the vent holes 74a is supplied to the respective through holes
73a through the slits 74b. The air is radiated from the end of the through hole 73a and cools the
heat of the coil 9 driven at this position. The cooling air is radially supplied to the coil 9 from a
plurality of angles, and the temperature rise is prevented without interfering with the vibration of
the voice coil unit 71. Therefore, even if a high power drive current is applied to the coil 9, the
temperature rise can be positively prevented.
[0048]
Next, a loudspeaker according to a seventh embodiment of the present invention will be
described with reference to FIG. FIG. 13A is a side view showing the structure of the voice coil
unit 81 of the speaker 80 of the seventh embodiment. Unlike the previous embodiments, an
overcurrent protection device is provided instead of the cooling member. As shown in the figure,
two terminals 83 are provided at the upper end 82a of the voice coil bobbin 82 around which the
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coil 9 is wound, and an overcurrent protection element 84 is connected to the terminals 83. The
overcurrent protection element 84 is a thinner and shorter wire than the wire of the coil 9 and
has a larger electrical resistance than the coil 9 in unit length. Therefore, when an excessive
current flows through the coil 9, the overcurrent protection element 84 is melted by Joule heat
to cut off the drive current of the voice coil section 81.
[0049]
FIG. 13 (b) is an enlarged view of a mounting portion of the overcurrent protection element 84.
The voice coil portion 81 configured in this manner is joined to the diaphragm 11 at the upper
end portion 82 a and vibrates by the drive current of the coil 9. When the drive current of the
coil 9 becomes excessive, the resistance of the overcurrent protection element 84 generates
Joule heat. If such a high resistance portion is not present, the temperature of the coil 9 rapidly
rises, and the coil 9 itself is melted and cut beyond the melting point of copper or aluminum
which is a coil material. If this happens, the coil 9 can not be replaced unless the diaphragm 11
and the suspension (not shown) are removed from the frame, making repair virtually impossible.
However, in the present embodiment, since the overcurrent protection device 84 is provided at
the upper end 82 a of the voice coil bobbin 82, replacement repair of the overcurrent protection
device 84 becomes possible. In this way, mechanical breakage of the coil 9 due to melting of the
coil 9 itself or the coil adhesive layer due to overheating can be prevented in advance.
[0050]
Next, a loudspeaker according to an eighth embodiment of the present invention will be
described with reference to FIG. FIG. 14A is a side view showing the structure of the voice coil
unit 91 of the speaker 90 of the eighth embodiment. Similar to the seventh embodiment, two
terminals 93 are provided at the upper end 92 a of the voice coil bobbin 92, and a thermal fuse
94 is connected to the terminals 93. FIG. 14 (b) is an enlarged view of the mounting portion of
the thermal fuse 94. Since the structure of the speaker 90 is the same as that of the seventh
embodiment except for the temperature fuse 94, the description will be omitted.
[0051]
In the speaker 90 having such a configuration, when a drive current is applied to the coil 9, Joule
heat is generated due to the resistance of the coil wire, and the temperature of the coil 9 rises.
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Therefore, when a large electric power is applied instantaneously, the temperature of the coil 9
rapidly rises when there is no high resistance portion, and the coil 9 exceeds the melting point of
copper or aluminum which is a coil material, and the coil 9 is melted down. However, in the
present embodiment, the temperature fuse 94 rises to a higher temperature first than the coil 9.
Further, the melting point of the thermal fuse 94 can be set freely as compared with the seventh
embodiment. Therefore, if the melting temperature of the thermal fuse 94 is set sufficiently lower
than the melting point of the coil 9, the thermal fuse 94 melts before the coil 9. For this reason, it
is possible to prevent in advance the melt breakage of the coil 9 and the mechanical breakage of
the coil 9 due to the breakage of the coil adhesive layer.
[0052]
Further, when the speaker 90 is driven with a large power for a long time, the temperature of the
entire voice coil portion 91 rises, and the temperature fuse 94 before the breakage of the
adhesive layer of the coil 9 and the mechanical damage of the voice coil portion 91. Works.
Therefore, replacement repair is possible without removing the diaphragm 11 and the
suspension from the frame.
[0053]
Next, a loudspeaker according to a ninth embodiment of the present invention will be described
with reference to FIG. FIG. 15 is a half sectional view showing the structure of the speaker 100 of
the ninth embodiment. The same reference numerals as in the conventional example denote the
same parts as in the conventional example, and a description thereof will be omitted. The voice
coil portion 101 is obtained by winding a coil 9 around the lower end outer peripheral portion of
a cylindrical voice coil bobbin 102 as in the prior art. The coil 9 is held in the air gap 7 of the
annular magnetic circuit 6 formed of the magnet 4, the top plate 5 and the center pole 3. The
voice coil bobbin 102 is bonded to the diaphragm 11 and the suspension 12 by adhesive layers
103a and 103b. The adhesive layer 103 is, for example, an adhesive that is self-extinguishing by
containing a phosphorus-based compound.
[0054]
In the speaker 100 configured as described above, when the coil 9 is driven with high power for
a long time, the temperature of the entire voice coil unit 101 rises. Then, the vicinity of the
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bonding point between the diaphragm 11 and the voice coil bobbin 102 and the vicinity of the
suspension 12 also have high temperatures. The diaphragm 11 is usually made of paper, and the
suspension 12 is made of cotton, but none of them has a high ignition point. However, in the
present embodiment, since the diaphragm 11 and the suspension 12 are fixed to the voice coil
bobbin 102 via the adhesive layer 103 having a self-extinguishing property, the vicinity of the
diaphragm 11 and the suspension 12 reaches the ignition point. Even in such a case, the selfextinguishing agent contained in the adhesive layer 103 works to block oxygen, and ignition can
be prevented in advance.
[0055]
As described above in detail, according to the invention of claim 1 of the present application, the
cooling surface area is effectively increased to suppress the temperature rise of the coil. In
addition, since the voice coil bobbin has a sandwich structure, it is lightweight and has high
rigidity, and is resistant to vibration and mechanical buckling. Furthermore, since the core
materials are insulated from each other, no eddy current is generated due to the drive current of
the coil.
[0056]
According to the invention of claim 2 of the present application, in addition to the effect of the
invention of claim 1, the efficiency of heat conduction of the core material is further improved, so
that the cooling effect of the coil is further enhanced.
[0057]
Further, according to the third and fourth inventions of the present application, in addition to the
effects of the first invention, heat is also dissipated from the dust cap, so the coil cooling effect is
further enhanced.
[0058]
Further, according to the fifth aspect of the present invention, the heat of the voice coil bobbin
can be cooled by the cooling member without using the composite member sheet.
In addition, although a plurality of notches are provided in the top plate, since the intervals are
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small, they function as air gaps for forming a magnetic circuit, and the efficiency of the
electromagnetic force does not decrease.
[0059]
Further, according to the sixth aspect of the present invention, the air in the peripheral portion of
the voice coil bobbin is easily exchanged, and the coil is cooled by the air.
[0060]
According to the seventh aspect of the present invention, by controlling the amount of air
supplied to the hollow member, it is possible to perform forced air cooling according to the
applied power of the coil.
[0061]
Further, according to the invention of claim 8 of the present application, by replacing the
overcurrent protection element, it becomes easy to repair the breakage of the speaker due to the
excessive power.
[0062]
Further, according to the invention of claim 9 of the present application, by providing the
thermal fuse, the temperature rise of the voice coil bobbin can be managed, and it becomes easy
to repair the breakage of the speaker due to the long time driving and the excessive power.
[0063]
Further, according to the invention of claim 10 of the present application, when the voice coil
bobbin is ignited, it is possible to prevent the burning of the suspension and the diaphragm and
to prevent the fire of the speaker in advance.
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