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JP2002271890

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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
financial decisions, should not be based on machine-translation output.
DESCRIPTION JP2002271890
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
small speaker. More particularly, the present invention relates to small speakers that can be
played with excellent sound quality and high sound pressure.
[0002]
2. Description of the Related Art A small speaker is used, for example, in reproducing a ring tone
on a mobile phone. Since such a small speaker has a low sound pressure, an input voltage to be
applied to the speaker is increased in order to increase the ringing tone. By the way, in such a
small-sized speaker, a film diaphragm is generally used, and a bobbinless voice coil is adhered in
the vicinity of the central portion of the diaphragm. Since the plastic film used for the diaphragm
has a poor thermal conductivity, the heat generated by the coil is not easily transmitted to the
diaphragm. Furthermore, since the coil itself is bobbinless (air core), the heat dissipation and
cooling efficiency of the coil itself are very bad. As a result, the coil temperature tends to rise, and
the coil (eg, the winding portion) may be destroyed by heat. As a result, reproduction with good
sound quality and high sound pressure is very difficult with conventional small speakers.
[0003]
Therefore, there is a strong demand for small speakers that can be reproduced with excellent
sound quality and high sound pressure.
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[0004]
SUMMARY OF THE INVENTION The present invention has been made to solve the abovedescribed conventional problems, and the object of the present invention is to provide a small
speaker capable of reproducing with excellent sound quality and high sound pressure. It is to do.
[0005]
A speaker according to the present invention comprises a diaphragm, a voice coil for driving the
diaphragm, and a magnetic circuit for forming a magnetic field intersecting the voice coil, and
the diaphragm The voice coil is coupled via a heat dissipation member.
[0006]
In a preferred embodiment, the voice coil is a bobbinless voice coil.
[0007]
In a preferred embodiment, the heat dissipation member includes at least one selected from
aluminum, duralumin, copper and stainless steel.
[0008]
In a preferred embodiment, the heat dissipation member has a thickness in the range of 10 to
200 μm.
[0009]
According to the present invention, since the voice coil and the diaphragm are coupled through
the heat dissipation member made of a specific heat conductive material, the heat generated in
the voice coil is transmitted through the heat dissipation member even when the input voltage is
large. Well diverge.
Therefore, an excessive temperature rise of the voice coil can be prevented.
As a result, a large input is possible, and a small speaker that can be reproduced with excellent
sound quality and high sound pressure can be obtained.
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[0010]
BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of the present
invention will be described below with reference to the drawings, but the present invention is not
limited to these embodiments.
[0011]
FIG. 1 is a schematic cross-sectional view of a speaker according to a preferred embodiment of
the present invention, and FIG. 2 is a schematic cross-sectional view enlarging a heat dissipation
member portion of the speaker.
The speaker 10 includes a diaphragm 1, a voice coil 2 for driving the diaphragm, and a magnetic
circuit 3 for forming a magnetic field intersecting the voice coil.
The outer periphery of the diaphragm 1 is supported by the wall of the frame 4.
One end of the voice coil 2 is coupled to the diaphragm 1 via the heat dissipation member 5, and
the other end is disposed in the magnetic gap of the magnetic circuit 3.
Although not shown, both ends of the coil portion of the voice coil 2 are drawn to the side of the
frame 4 and connected to an external audio input signal portion.
The magnetic circuit 3 has a yoke 6, a magnet 7 and an upper plate 8 disposed above the yoke 6,
and forms a magnetic field intersecting with the voice coil 2. The yoke 6 and the frame 4 are
integrated by insert molding or bonded by an adhesive. The frame 4 is made of any suitable
material, but is typically made of resin.
[0012]
The diaphragm 1 is typically formed of a resin film. Any suitable resin may be used depending on
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the purpose and application, but typically, polyetherimide (PEI), polyethylene terephthalate
(PET), polycarbonate (PC) are used. Particularly preferred resins are polyetherimides.
Adhesiveness, heat resistance and internal loss are suitable for the use environment. The
thickness of the diaphragm 1 may also vary depending on the purpose and application, but is
typically 20 to 70 μm, more preferably 30 to 60 μm. By having the thickness in such a range, it
is possible to achieve an f0 value (300 to 500 Hz) and a reproduction band optimal for a small
speaker.
[0013]
The voice coil 2 may be an air core (bottleless) or may have a bobbin, but the effect of the
present invention is remarkable in the case of the bobbinless. Since the bobbinless voice coil is
inferior in heat radiation and cooling efficiency as compared with the case of having a bobbin,
the improvement effect by the present invention is further enhanced.
[0014]
The heat dissipation member 5 is made of a material having excellent thermal conductivity. Here,
"a material having excellent thermal conductivity" means a material having a thermal
conductivity sufficient to dissipate heat generated from the voice coil, and it does not matter
whether it is metal or nonmetal. Representative examples of such materials include aluminum,
duralumin, copper and stainless steel. Particularly preferred materials are aluminum and
duralumin. Since the hardness is sufficiently large as compared with the diaphragm material,
even if it is disposed between the voice coil and the diaphragm, the transmission loss of the
driving force does not occur, and moreover, the machinability is excellent. These materials may
be used alone or in combination of two or more. The combination method may be a mixed
material such as an alloy, or may be a foil or a film made of a single material. Typically, the heat
dissipation member 5 is formed of a metal foil containing at least one of the above materials.
[0015]
The heat dissipating member 5 may have any suitable shape such that the diaphragm 1 and the
voice coil 2 can be coupled via the heat dissipating member 5. Typically, as shown in FIG. 2, the
heat dissipation member 5 covers the end of the voice coil 2 on the diaphragm side, and has a
cross-sectional shape that monotonously extends from the voice coil along the diaphragm
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direction. (That is, a trapezoidal cross-sectional shape in which the long side portion is open).
Although FIG. 2 shows a cross-sectional shape in which the oblique side of the trapezoid is a
convex upward curve, the oblique side may be a straight line or a downward convex curve. By
having such a shape, an excellent heat dissipation effect can be obtained. Also, for example, the
shape of the heat dissipation member 5 may be a shape as shown in FIG. 3 or another shape, and
may be appropriately designed according to the purpose, application, and diaphragm shape.
[0016]
The heat radiating member 5 preferably has a thickness of 10 to 200 μm, more preferably 20 to
100 μm, and particularly preferably 30 to 80 μm. By having such a thickness, it is possible to
minimize the transmission loss of the voice coil driving force to the diaphragm and to sufficiently
dissipate the heat generated by the voice coil.
[0017]
The heat dissipation member 5 is coupled to the diaphragm 1 and the voice coil 2 by any
appropriate means. Typically, the heat dissipation member 5 is coupled to the diaphragm 1 and
the voice coil 2 using an adhesive.
[0018]
The speaker of the present invention can be suitably used for a small audio device, a small
information device (for example, a mobile phone) and the like.
[0019]
As described above, according to the present invention, by combining the voice coil and the
diaphragm via the heat dissipating member made of a specific heat conductive material,
reproduction with excellent sound quality and high sound pressure is achieved. Possible small
speakers are obtained.
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