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JP2008042532

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DESCRIPTION JP2008042532
A speaker for efficiently cooling a voice coil, suppressing temperature rise of the voice coil, and
outputting stable sound pressure with high input resistance and large output. A magnet 18 is
disposed between a magnetic upper plate 20 and a lower plate 12 and has a magnetic circuit
formed via a center pole 14 extending from the center of the lower plate 12. An annular
magnetic gap 24 formed between the center pole 14 and the upper plate 20, a frame 26 fixed to
the upper surface of the upper plate 20, and a vent 40 ventilable in the axial direction along the
inside of the cylinder wall A plurality of bobbins 30 are provided, and the bobbin 30 is provided
with the recess 36 on the entire circumference along the circumferential direction of the outer
circumference. The voice coil 38 wound in the recess 36 of the bobbin 30 and positioned in the
magnetic gap 24, and the diaphragm 28 whose outer edge is fixed to the periphery of the frame
26 and the bobbin 30 is connected to the central portion The bobbin 30 vibrates in the axial
direction of the cylinder. [Selected figure] Figure 1
スピーカ
[0001]
The present invention relates to a speaker having a function of radiating heat generated in a
voice coil.
[0002]
Conventionally, a voice coil which is a member constituting a speaker is wound around a bobbin
connected to a diaphragm, and when a drive current which is an acoustic signal is input, the
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bobbin is vibrated by the voice coil and coupled to this The diaphragm is driven to output sound
pressure.
At this time, the voice coil generates heat due to the drive current. Generally, since the space
forming the magnetic gap of the speaker is narrow, the air inside the speaker can not easily
ventilate with the external space, and the heat of the voice coil is not sufficiently dissipated and is
difficult to be cooled. As a result, the resistance value of the voice coil increases due to heat
generation, and the input current may decrease, making it impossible to obtain an appropriate
output sound pressure. Furthermore, the voice coil and the bobbin itself are thermally deformed,
or the voice coil peels off from the bobbin and contacts the inner circumferential surface of the
upper plate forming the magnetic gap, resulting in breakage due to generation of abnormal noise
or disconnection. There was also a possibility.
[0003]
Therefore, as a speaker having a function of effectively cooling a voice coil generating heat, in
Patent Document 1, it is between the inner peripheral surface of the plate in which the magnetic
gap is formed and the outer peripheral surface of the center pole facing the inner peripheral
surface of the bobbin. Further, there is disclosed a vent provided with a vent in which the inner
surface of the magnetic gap forming portion is cut away, and a vent being formed. In the speaker,
when the diaphragm vibrates, air flows in the air passage to cool the voice coil wound around the
bobbin.
[0004]
Further, according to Patent Document 2, the first vent hole cut out at a predetermined interval is
provided on the inner peripheral surface of the upper plate of the first speaker, and the lower
plate near the center pole base is provided with the first vent at a predetermined interval. A
loudspeaker provided with two vents is disclosed. This speaker is attached at a back position
coaxial with the first speaker, and a second speaker smaller in diameter than the first speaker is
opened to the outside, and the backs of the first speaker and the second speaker are connected It
is formed in communication with the trachea. Then, air flows through the vent of the first
speaker by the vibration of the second speaker, thereby cooling the voice coil.
[0005]
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2
In Patent Document 3, the holder of the speaker is provided with a vent communicating with the
magnetic gap, and the bobbin is provided with an extension which is extended in the axial
direction of the cylinder and formed so as to enter the vent. Speaker device is disclosed. As a
result, the heat of the voice coil is transmitted via air to a member such as a magnet that forms a
magnetic gap, and the lower part is extended to be transmitted also to the bobbin whose surface
area is increased to be cooled, and further magnetic Since the vent communicating with the gap
portion is in contact with the outside air, it is efficiently cooled.
[0006]
In addition, in Patent Document 4, a vent hole is formed in the center of the center pole in a
penetrating state, and the pressure on the internal air generated by the vibration of the
diaphragm by the voice coil is released from the vent hole and passed from the outside. There is
disclosed a speaker device in which intrusion of foreign matter such as misty wax into pores is
prevented. JP-A-8-140192 JP-A-8-168090 JP-A-2004-56544 JP-A-5-316592
[0007]
However, in the above-mentioned prior art, the magnetic gap formed between the inner
peripheral surface of the upper plate constituting the speaker and the center pole is narrow, and
air is ventilated to cool the voice coil inserted between the magnetic gaps. Was not enough. In
Patent Document 1, air for cooling the voice coil passes through the vent provided in the inner
peripheral surface of the upper plate and the vent provided in the outer peripheral surface of the
center pole facing this, but the airtightness of the damper Is not high enough to be breathable.
Therefore, the air permeability of the damper was an obstacle, and the air permeability around
the voice coil was not sufficient.
[0008]
Further, in Patent Document 2, semicircular notches are formed at predetermined intervals in
communication with the inner peripheral surface of the upper plate, the center pole outer
peripheral surface, and the lower plate of the first speaker, but the positions where the cutouts
are not formed However, since the gap with the voice coil is narrow and the ventilation is not
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sufficient, cooling is difficult. In addition, the magnetic gap widens at the notched portion, and
the efficiency of converting an electrical signal into sound drops.
[0009]
Furthermore, in Patent Document 3, although the heat of the voice coil is transmitted to the
member forming the magnetic gap through the air and dissipated, the air does not have high
thermal conductivity and the distance between the magnetic gaps is narrow. , Voice coil cooling
was not enough.
[0010]
In addition, in Patent Document 4, the air inside the center cap is easily ventilated by the
vibration of the diaphragm by the vent hole penetrating in the center of the center pole.
However, in the magnetic gap where the voice coil is located, the distance between the voice coil
and the inner peripheral surface of the upper plate which is the upper plate is narrow, and the air
circulation at the lower bobbin outer peripheral position is not sufficient inside the ring magnet.
The cooling of the voice coil was also not sufficient.
[0011]
SUMMARY OF THE INVENTION The present invention has been made in view of the problems of
the prior art, and is a speaker which cools the voice coil efficiently, suppresses the temperature
rise of the voice coil, and outputs stable sound pressure with high input resistance and large
output. Intended to provide.
[0012]
According to the present invention, a magnet is disposed between a top plate and a bottom plate
of a magnetic body, and a magnetic circuit formed through a center pole extending from the
center of the bottom plate, and a magnet circuit is formed between the center pole and the top
plate. A plurality of annular magnetic gaps, a frame fixed to the upper surface of the upper plate,
and a plurality of vent holes ventilable in the cylinder axial direction along the inside of the
cylinder wall, and along the circumferential direction of the outer periphery Vibration with a
bobbin provided with a recess around the entire circumference, a voice coil wound around the
recess of the bobbin and positioned in the magnetic gap, and an outer edge fixed to the periphery
of the frame and the bobbin connected to the center A speaker comprising: a plate, wherein the
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bobbin vibrates in the cylinder axial direction in the magnetic gap to allow air to pass through
the vent hole of the bobbin.
[0013]
The lower plate and the center pole are provided with a vent hole penetrating at a central
portion, and a speaker in which the air is circulated by the vibration of the bobbin.
The outer periphery of the voice coil wound around the recess of the bobbin does not protrude
from the recess.
Further, the inside of the vent hole is in communication with the inner surface of the recess
provided on the outer periphery of the bobbin.
[0014]
Further, the voice coil wound around the bobbin may be wound into one layer or a usual
multilayer.
[0015]
According to the speaker of the present invention, the voice coil formed by winding the wire in
the recess of the bobbin is cooled by the air passing through the vent formed in the inside of the
bobbin cylindrical wall, and the temperature rise of the voice coil is suppressed Be
Therefore, it is possible to output a stable sound pressure with a high input resistance and a large
output and for a long time use. In addition, the structural mass increase of the bobbin is small,
and highly efficient music reproduction can be achieved over a long time, compared to the
conventional one.
[0016]
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Hereinafter, an embodiment of a speaker according to the present invention will be described
based on FIGS. 1 to 3. In the speaker 10 of this embodiment, as shown in FIG. 1, a cylindrical
center pole 14 is integrally formed at the center of a circular lower plate 12 made of metal
magnetic material, and an axial direction is formed at the center pole A vent hole 16 is formed in
the through hole. Further, the top end outer peripheral surface 14a of the center pole 14 is
formed to have substantially the same width as the thickness of the upper plate 20 described
later, and is formed to be slightly thicker than the lower periphery thereof. A ring-shaped magnet
18 having a thickness reaching the lower end of the top end outer peripheral surface 14 a of the
center pole 14 and having a slightly larger outer diameter than the lower plate 12 is coaxially
disposed in the lower plate 12. A ring-shaped upper plate 20 made of a metallic magnetic
material is coaxially mounted on the magnet 18 to form a magnetic circuit.
[0017]
The upper plate 20 is formed to be slightly smaller in outer diameter than the magnet 18, and
the central opening is formed to be slightly smaller in diameter than the opening of the magnet
18. Further, a gap is provided between the top end outer peripheral surface 14 a of the center
pole 14 and the inner peripheral surface 20 a of the central opening of the upper plate 20 to
form a magnetic gap 24.
[0018]
The small diameter opening side of the hollow truncated cone-shaped frame 26 is attached to the
top plate 20 on the top surface of the top plate 20 forming the magnetic circuit. The frame 26
may have any suitable shape, and a space such as a hole or a groove may be formed on the side
surface. The large diameter end of the truncated cone shaped diaphragm 28 is fixed to the edge
on the large diameter opening side of the frame 26. The cylindrical bobbin 30 is inserted into the
central opening of the diaphragm 28 and is connected to the upper side of the outer periphery of
the bobbin 30. Also, a dome-shaped center cap 32 is attached to the diaphragm 28 so as to cover
the opening of the bobbin 30. Furthermore, on the bobbin 30 fixed to the central portion of the
diaphragm 28, the inner peripheral edge of the annular damper 34 located below the diaphragm
28 and whose outer peripheral edge is fixed to the inside of the frame 26 is It is fixed and the
bobbin 30 is also supported by the inner peripheral edge of the damper 34.
[0019]
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The outer peripheral center portion of the bobbin 30 is provided with a recess 36 such that the
entire periphery is cut out along the circumferential direction as shown in FIG. 2 with an
appropriate width. In the recess 36, the coil wire is wound in a single layer or in an appropriate
number of layers with an appropriate number of turns, and a voice coil 38 having an outer
diameter lower than that of the outer peripheral surface of the bobbin 30 is formed. Further, as
shown in FIG. 2 and FIG. 3, inside the cylindrical wall of the bobbin 30, a plurality of vent holes
40 are formed over the entire circumference in the axial direction, and the vent holes 40 are
formed in the central axis direction of the voice coil 38. ing. In addition, the recess 36 may be in
communication with the vent 40.
[0020]
Then, the bobbin 30 is inserted so that the voice coil 38 is positioned in the space in which the
magnetic gap 24 is formed, and is brought into contact with the inner peripheral surface 20 a of
the upper plate 20 and the top outer peripheral surface 14 a of the center pole 14. Instead, they
are formed so as to be oscillated in the direction orthogonal to the magnetic field direction by the
magnetic gap 24 with a proper gap.
[0021]
Next, the operation of the speaker 10 of this embodiment will be described.
When an acoustic signal is input from a lead wire (not shown) connected to the voice coil 38, the
bobbin 30 inserted in the magnetic gap 24 vibrates and the diaphragm 28 is driven. At the same
time, the voice coil 38 generates heat due to the electrical input. At this time, when the bobbin
moves in the cylinder axial direction, as shown in FIGS. 1 and 3, air moves in the vent holes 40
formed inside the cylinder wall in accordance with the movement of the bobbin 30. For example,
when the bobbin 30 moves downward, air in a space 42 surrounded by the lower plate 12, the
center pole 14, the magnet 18, and the upper plate 20 flows into the air holes 40 of the bobbin
30. At this time, the airflow of the air moving through the vent hole 40 takes heat of the voice
coil 38 as it passes around the voice coil 38, and the warmed air moves inside the center cap 32.
At the same time, the air in the center cap 32 is exhausted to the outside from the vent holes 16
of the center pole 14. Conversely, when the position of the center cap 32 moves upward due to
the vibration of the diaphragm 28, external air is sucked from the vent holes 16 of the center
pole 14, and the temperature of the air in the center cap 32 decreases. At this time, at the same
time, the air in the center cap 32 flows into the air hole 40 of the bobbin 30, and the air flow of
air moving through the air hole 40 passes around the voice coil 38 and simultaneously takes
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heat of the voice coil 38. Cooling. Then, the warmed air mixes with the air of the external space
and is cooled. As described above, air is repeatedly ventilated through the vent holes 40 of the
bobbin 30 in accordance with the vibration of the diaphragm 28, and the voice coil 38 is cooled.
[0022]
According to the speaker 10 of this embodiment, the voice coil 38 wound and formed in the
recess 36 of the bobbin 30 is cooled by the air passing through the vent hole 40 formed inside
the cylindrical wall of the bobbin 30, The temperature rise of the coil 38 is reduced. Therefore, it
is possible to output a stable sound pressure with high input resistance and large output. In
addition, since the air in the internal space of the speaker 10 is ventilated to the outside by the
vent holes 16 formed in the center pole 14, the temperature rise of the air in the space portion
42 and the center cap 32 can be suppressed. In addition, ventilation of air inside the speaker 10
by the vibration of the diaphragm 28 and the center cap 32 is improved, and a decrease in
compliance and non-linearity in driving the diaphragm 28 due to expansion and compression of
the internal air are improved. And distortion can also be reduced.
[0023]
Further, the voice coil 38 is wound in the recess 36 of the bobbin 30, and the voice coil 38 does
not come in contact with the inner peripheral surface 20a of the upper plate 20, which is safe.
Furthermore, the coil wire may be wound twice to form the voice coil 38, and the outer periphery
of the voice coil 38 may be formed so as not to protrude from the outer peripheral surface of the
bobbin 30. When the coil wire of the voice coil 38 is wound in a plurality of layers, it is possible
to output a stable sound pressure with a larger output than the voice coil 38 formed in a single
layer.
[0024]
Furthermore, the forming position of the voice coil 38 is, for example, forming the concave
portion 36 at the same position on the outer peripheral surface and the inner peripheral surface
of the bobbin 30, winding the coil wire material respectively, and forming the voice coil 38
integrally on the back and front. But it is good. As a result, sound pressure can be output with
higher output.
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[0025]
The speaker according to the present invention is not limited to the above embodiment. For
example, as shown in FIG. 4, there is no vent hole 16 at the center of the lower plate 12 and the
center pole 14. The upper end may be closed, and an opening 44 may be formed between the
diaphragm 28 and the damper 34. In this case, ventilation is performed between the space on the
lower surface side of the magnetic gap 24 and the space on the back side of the diaphragm 28
from the space on the back side of the frame 26 of the speaker 10.
[0026]
In addition to the shape shown in FIG. 2, the shape of the air vent of the bobbin may be a cross
section of a corrugated board, and the air vent may be provided at an appropriate position.
Further, the diameter and the material of the diaphragm of the speaker can be appropriately set
in accordance with the acoustic signal to be reproduced. The material for forming the bobbin
may be a nonmagnetic material, and it is more preferable that the material has good thermal
conductivity, and the size of the bobbin can be appropriately set according to the size of the
speaker. Furthermore, the shape and material of each member can be appropriately changed.
[0027]
It is a schematic longitudinal cross-sectional view of the speaker of one embodiment of this
invention. It is a perspective view which shows the bobbin and the voice coil wound around the
speaker of this embodiment. It is a schematic longitudinal cross-sectional view of the bobbin by
which the voice coil of the speaker of this embodiment was wound. It is a schematic longitudinal
cross-sectional view of the speaker of other embodiment of this invention.
Explanation of sign
[0028]
DESCRIPTION OF SYMBOLS 10 Speaker 12 lower plate 14 center pole 16 air vent 18 magnet 20
upper plate 24 magnetic gap 26 frame 28 diaphragm 30 bobbin 34 damper 36 recessed part 38
voice coil 40 air vent
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