JPS61161899

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DESCRIPTION JPS61161899
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
magnetic shielding speaker using a defective magnet for leakage flux cancellation. 2. Description
of the Related Art In recent years, magnetic shielding speakers have come to be widely used
because they do not modulate the screen even if they are placed beside a television. Hereinafter,
an example of the above-mentioned conventional magnetic shielding speaker will be described
with reference to the drawings. FIG. 2 is a cross-sectional view of a conventional magnetic
shielding speaker. 1 is a yoke, 2 is a magnet, 3 is a top plate, 4 is a frame, 6 is a voice coil, 6 is a
center cage, T is a cone, 8 is a dust cap, 9 is an edge, and 10 is an arrow. Reference numeral 11
denotes a magnetic shielding magnet, which is attached to the back of the yoke 1 so as to face
the magnet 2. A magnetic shielding cover 12 is formed in a cup shape and made of a material
having good magnetic permeability such as an iron plate, the bottom is joined to one side of the
magnet 11, and the opening is joined to the outer peripheral wall of the top plate 3. 13 is a
center pole portion of the yoke 1; The operation of the magnetic shielding speaker configured as
described above will be described below. Now, assuming that there is no magnet 11 and only the
magnetic shielding cover 12 is coupled, the magnetic flux leaking to the outside from the top
plate 3 is only directed to the center ball portion 13 of the yoke 1. The magnetic flux leaking
from the upper surface and the side of the top plate 3 to the bottom and the side of the yoke 1
through the air passes through the magnetic shield 12 and hardly leaks to the outside of the
magnetic shield 12. However, in this state, since the magnetic resistance between the magnetic
shielding cover 12 and the bottom surface of the yoke 1 is reduced, the magnetic flux density of
the magnetic gap formed by the center pole 13 and the inner peripheral surface of the top plate
3 is lowered to deteriorate the efficiency of the speaker. Therefore, if the magnet 11 magnetized
to the above polarity is inserted between the magnetic shielding cover 12 and the bottom surface
of the yoke 1, the magnetic resistance during this time apparently increases, and the magnetic
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flux leaking from the magnetic shielding cover 12 to the bottom surface of the yoke 1 almost
disappears. It is possible to eliminate the efficiency drop. Problems to be Solved by the Invention
However, in the configuration as described above, the magnet 11 needs to be approximately the
same size as the magnet 2 and has the problem of being expensive. In view of the above
problems, the present invention provides an inexpensive magnetic shielding speaker. Means for
Solving the Problem In order to solve the above-mentioned problems, the magnetic shielding
speaker of the present invention is magnetized in the opposite polarity to the field portion
composed of the magnet, the yoke and the top plate, and the position opposed to the magnet.
From a magnet for magnetism having a chip, a crack and a crack joined to the bottom of the
yoke, and a magnetism cover having an opening on the bottom and an opening on the side of the
top plate on the other surface of the magnet for magnetism. The configuration is as follows.
Operation According to the present invention, a magnet for magnetic shielding can be obtained
at low cost by the above-described configuration, and the cost reduction of the entire speaker is
achieved. EXAMPLE An example of the present invention will be described below with reference
to FIG. The configuration is substantially the same as that of the conventional example shown in
FIG. In the embodiment of the present invention, a magnet 14 having a crack, a notch or the like
is used as a magnet for magnetic shielding. Such magnets can be obtained at a much lower cost
than non-defective ones, which magnet makers have been regenerating or discarding as defects
until now. The magnet 14 in such a case does not change the magnetic shielding effect in any
way, and does not enter the voice coil portion even if a piece of the magnet is dropped, so it does
not cause defects such as gap rubbing. As described above, according to the present embodiment,
it is possible to realize a magnetic shielding speaker at low cost by using a magnet having a
crack, chipping 9 or the like as the magnetic shielding magnet. Effect of the Invention As
described above, according to the present invention, the magnetic field portion comprising the
magnet, the yoke, and the top plate, and the chipped and cracked portion magnetized in reverse
polarity in the position opposite to the magnet and joined to the bottom surface of the yoke. An
inexpensive magnetic shielding speaker can be supplied by providing a magnetic shielding
magnet having a crack, a bottom portion on the other surface of the magnetic shielding magnet,
and a magnetic shielding cover having an opening portion bonded to the side surface of the top
plate.
[0002]
Brief description of the drawings
[0003]
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FIG. 1 is a cross-sectional view of a magnetic shielding speaker according to an embodiment of
the present invention, and FIG. 2 is a cross-sectional view of a conventional example.
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