JPH0720796

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DESCRIPTION JPH0720796
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an
improvement of a speaker, and more particularly, to a speaker having a protective wire mesh for
protecting a diaphragm attached to the front.
[0002]
2. Description of the Related Art In a conventional speaker, as shown in FIG. 5, a ring-shaped
magnet 2 and a ring-shaped top plate 3 are sequentially formed on a back plate 1 having a
convex cross section in which a pole 1a is formed at the center. An edge-integrated dome-shaped
diaphragm 5 is supported by the voice coil 4 placed in the magnetic gap formed by the pole 1 a
and the top plate 3 and the inner peripheral edge of the top plate 3. Is constructed by attaching a
protective wire mesh 7 made of a magnetic material that covers and protects the diaphragm 5 to
the frame 6 to which is fixed.
[0003]
The flow of magnetic lines of force in such a conventional loudspeaker will be described with
reference to FIG.
[0004]
In FIG. 6, assuming that the polarity of the magnet 2 is N on the back plate 1 side and S on the
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top plate 3 side, the poles 1a and top plate 3 have N and S poles respectively. A main magnetic
flux for driving the voice coil 4 is generated in the magnetic gap between 1 a and the top plate 3.
Further, at this time, in this conventional speaker, since the protective wire mesh 7 is made of a
magnetic material, a jumping magnetic flux is generated between the pole 1a and the protective
wire mesh 7 as a magnetic flux other than the main magnetic flux.
Therefore, in this conventional speaker, the protective wire mesh 7 itself also functions as a part
of the magnetic circuit.
[0005]
However, in general, in the magnetic circuit of the speaker, it is considered ideal that the
magnetic force concentrates only on the magnetic gap, and a conventional magnetic flux
generated in such a protective metal mesh is generated. The loudspeaker is against this ideal, and
furthermore, in this conventional loudspeaker, the protective mesh itself acts as a part of the
magnetic circuit, so that the magnetic flux generated when driving the voice coil passes between
the pole and the protective mesh. The magnetic flux interferes with the magnetic flux to generate
magnetostriction, which adversely affects the sound quality.
[0006]
Further, there are also cases where the protective wire mesh reflects noise emitted from the
diaphragm or the protective wire mesh itself resonates to generate abnormal noise.
[0007]
Therefore, the present invention solves the disadvantages of the prior art, prevents the
generation of jump flux to the protective mesh, and prevents the magnetic flux from passing
through the protective mesh, thereby suppressing the generation of magnetostriction, An object
is to provide a speaker capable of high-quality sound reproduction.
[0008]
A speaker according to the present invention for achieving the above object is, in the speaker
according to the first aspect of the present invention, a speaker in which a protective wire mesh
7 for protecting the diaphragm 5 is attached to the front surface. A second magnet 8 magnetized
so that the magnetic pole on the pole 1a side has the same pole as the magnetic pole of the pole
1a formed by the first magnet 2 is fixed on the pole 1a substantially central axis of the wire mesh
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7 In the second aspect of the present invention, the sound absorbing material 9 is directly or
through a protective wire mesh 7 on the surface of the second magnet 8 facing the diaphragm 5.
In the third aspect of the present invention, the vibration absorbing material 10 is fixed to a part
of the protective mesh 7 in the speaker according to the first or second aspect.
[0009]
[Function] In such a speaker, the second magnet magnetized so that the pole on the pole side has
the same pole as the pole of the pole is fixed on the pole substantially central axis of the
protective wire mesh. Thus, the magnetic flux from the pole toward the front of the diaphragm is
guided into the magnetic gap by the magnetic flux in the opposite direction from the second
magnet.
Therefore, the magnetic flux does not pass through the protective metal mesh, and the density of
the magnetic flux passing through the magnetic gap becomes high.
[0010]
Further, in the above-mentioned speaker in which the sound absorbing material is fixed to the
surface of the second magnet facing the diaphragm directly or through a protective metal mesh,
the vibration plate of the second magnet is operated by the function of the sound absorbing
material. In the above-described speaker in which the reflection of sound by the opposite surface
of the speaker is prevented and the vibration absorbing material is fixed to a part of the
protective wire mesh, the vibration generated by the protective wire mesh is absorbed by the
vibration absorbing material.
[0011]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 is a cross-sectional view of a
speaker according to an embodiment of the present invention, and FIG. 2 is a flow of magnetic
lines of force of the speaker according to the embodiment. FIGS. 3 and 4 are sectional views for
explaining the mounting structure of the second magnet of the speaker in another embodiment
of the present invention.
[0012]
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In the figure, reference numeral 1 denotes a back plate having a convex cross section in which
poles are formed at the center, and 2 is a ring-shaped first magnet coaxially mounted on the back
plate 1, 3 Is a ring-shaped top plate coaxially mounted on the first magnet 2;
A voice coil 4 is inserted in a magnetic gap formed by the pole 1a and the top plate 2. A
diaphragm 5 is a dome-shaped diaphragm made of metal whose edges are integrally formed. Are
supported by the voice coil 4 and the inner peripheral edge of the top plate 3.
A frame 6 is fixed on the top plate 3. By mounting the frame 6, the speaker itself is fixed to a
baffle plate or the like.
[0013]
The numeral 7 denotes a protective metal gauze made of a magnetic material attached to the
frame 6 to cover and protect the diaphragm 5, and on the side of the diaphragm 5 of the
protective metal gauze 7 on the central axis of the pole 1a. A disk-shaped second magnet 8 is
fixed so that the pole on the pole 1a side is the same as the pole of the pole 1a.
A sound absorbing material 9 made of felt is fixed to the second magnet 8, and a vibration
absorbing material 10 made of rubber, felt or the like is fixed to the center of the surface of the
protective wire mesh 7.
[0014]
The flow of magnetic lines of force of the loudspeaker in such an embodiment will be described
with reference to FIG.
[0015]
In FIG. 2, assuming that the polarity of the first magnet 2 is the N pole on the back plate 1 side
and the S pole on the top plate 3 side as in the explanation of the conventional loudspeaker, the
pole 1 a and the top plate 3 are The polarity is N pole and S pole respectively.
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The second magnet 8 is magnetized so that the pole on the pole 1a side is the same as the pole of
the pole 1a, so the diaphragm 5 side is the N pole and the protective mesh 7 side is the S pole.
In the loudspeaker of this embodiment, a main magnetic flux for driving the voice coil 4 is
generated which passes through the magnetic gap between the pole 1 a and the top plate 3.
As other magnetic fluxes, magnetic flux coming out from the pole 1a toward the front surface of
the diaphragm 5 can be considered, but this magnetic flux is led into the magnetic gap by
generation of magnetic flux in the reverse direction from the second magnet 8 It will be. For this
reason, in the loudspeaker of the embodiment, the density of the magnetic flux passing through
the magnetic gap becomes high. Furthermore, since the magnetic flux does not pass through the
protective metal mesh 7, the magnetic flux generated at the time of driving the voice coil 4 is not
interfered, and the generation of the magnetostriction is suppressed.
[0016]
Further, in the speaker of this embodiment, the reflection of the radiation sound from the
diaphragm 5 by the second magnet 8 is prevented by the function of the sound absorbing
material 9, and furthermore, the protective mesh 7 itself is made by the vibration absorbing
material 10. Because the vibration that occurs is absorbed, the protective mesh 7 does not
resonate, and so-called squeal in the protective mesh 7 is suppressed.
[0017]
As a fixing structure of the second magnet 8 to the protective wire mesh 7, as shown in FIG. 3,
the central portion of the protective wire mesh 7 is made to project to the front, and a recess 7a
is formed in the inside. Even if the second magnet 8 is fixed to the portion 7a, the sound
absorbing material 9 is fixed to the opposing surface of the second magnet 8 and the diaphragm
5, and the vibration absorbing material 10 is fixed to the front surface of the protective wire
mesh 7 Good.
Conversely, the second magnet 8 may be fixed by projecting the central portion of the protective
wire mesh 7 to the rear surface and forming the recess 7a on the front surface of the protective
wire mesh 7. In this case, the protection located on the front surface of the diaphragm 5 The
sound absorbing material 9 is fixed to the protruding portion of the wire mesh 7 (not shown).
Further, as shown in FIG. 4, the central portion of the protective mesh 7 is slightly protruded to
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the rear surface, and a slight depression 7 a is formed on the front surface of the protective mesh
7. The second magnet 8 to which the sound absorbing material 9 is fixed is fixed to the other
surface, and the vibration absorbing material 10 may be fixed in the recess 7a so as to form the
same surface as the front surface of the protective wire mesh 7. In this case, as viewed from the
outside of the speaker, no projecting portion or hollow portion is formed on the front surface of
the protective mesh 7. Since the fixing structure portion is on the same surface, the speaker is
excellent in appearance. In addition, the vibration absorbing material 10 used in the embodiment
may use an adhesive having damping property such as rubber, etc., and only by bonding the
second magnet 8 to the protective wire mesh 7 using this adhesive. However, the effect of
preventing the resonance of the protective wire mesh 7 can be obtained.
[0018]
Although the speaker according to the present invention has been described in detail based on
the embodiment considered to be representative, the embodiment of the speaker according to
the present invention is not limited to the structure of the above-mentioned embodiment. The
shape of the second magnet is not limited to a disk but may be a ring, etc., having the
configuration requirements described in the claims of the above-mentioned utility model
registration, exhibiting the effect referred to in the present invention, and the effects described
below As long as it has, it can modify suitably and can carry out.
[0019]
In the loudspeaker according to the present invention, the pole on the pole side is magnetized on
the pole substantially central axis of the protective wire mesh so as to have the same polarity as
the pole of the pole formed by the first magnet. Because the second magnet is fixed, the magnetic
flux from the pole toward the front of the diaphragm is guided into the magnetic gap by the
reverse magnetic flux from the second magnet and passes through the magnetic gap. Since the
density of the magnetic flux is increased, a large driving force is given to the voice coil, and
further, since the magnetic flux does not pass through the protective wire mesh, the magnetic
flux generated at the time of driving the voice coil is not interfered, and generation of
magnetostriction is suppressed. High-quality sound reproduction is performed.
[0020]
Further, in the speaker of the present invention in which the sound absorbing material is fixed to
the surface of the second magnet facing the diaphragm directly or through a protective metal
mesh, the vibration of the second magnet is caused by the function of the sound absorbing
material. In the speaker of the present invention in which the reflection of the sound by the
opposite surface to the plate is prevented and the vibration absorbing material is fixed to a part
of the protective metal mesh, the vibration generated by the protective metal mesh itself is
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absorbed by the vibration absorbing material. Will not resonate, and the noise of the protective
mesh will be suppressed.
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