JPS6132697

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DESCRIPTION JPS6132697
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
speaker in which a gap between a tubular member integrally fixed to a diaphragm and a frame is
sealed with a magnetic fluid using a magnetic fluid holding magnetic circuit. BACKGROUND OF
THE INVENTION FIG. 2 is a cross-sectional view showing a conventional example of a domeshaped speaker in which the peripheral edge of a dome-shaped diaphragm is cylindrically
enclosed. In FIG. 2, 1 is a dome-shaped diaphragm (hereinafter referred to as a diaphragm), 2 is a
tubular portion, 3 is an adhesive, 4 is a voice coil, 5 is a spy I ", 6 is a spidering, and 7 is A frame
8 is a magnetic circuit for holding a magnetic fluid, 9 is a magnetic fluid, 111) a center ball, 11 is
a yoke plate, and 13 magnets. As shown in FIG. 2, the diaphragm 1 and the cylindrical portion 2
at the periphery of the diaphragm are coupled via an adhesive 5. The cylindrical portion 2 also
has a bobbin, and a voice coil 4 is wound. The magnetic fluid holding magnetic circuit 8 provided
behind the surface of the frame 70 has its inner side surface and the outer side surface of the
cylindrical portion 2 facing each other, and the gap between them is sealed with the magnetic
fluid 9 . Since the magnetic fluid holding magnetic circuit 8 is magnetized in the axial direction, it
holds the magnetic fluid 9 by suction. In the conventional speaker having such a structure, the
magnetic fluid holding magnetic circuit is provided to prevent the magnetic fluid 9 from
scattering under the influence of the image pickup movement of the diaphragm 1 and keeping
the surface of the frame 7 dirty from being busy. As described above (usually, the outer surface
of the cylindrical portion 2 provided at the back of the surface of the frame 7 and provided at the
periphery of the diaphragm, the inner surface of the magnetic fluid holding magnetic circuit 8
and the inside of the frame 7). The side faces are arranged so as to face each other by 5 JC, and
the respective gaps are made straight and can be configured to be narrow and uniform @ 0 to
maintain the sealing force of the magnetic fluid 9 and The generation of abnormal noise due to
rolling or the like is more reliably suppressed by the stress generated by the magnetic fluid 9.
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However, in such prior art. When the speaker is operated, there is a phenomenon that the sealed
magnetic fluid 9 is pushed out to the surface side of the frame 7 from the gap, especially when
the amplitude is large, and this becomes remarkable. As the surface of the diaphragm 1 and the
frame 7 flow in such a large amount, the magnetism of the original magnet sealing the gap The
amount of fluid 9 is reduced by the amount of outflow, and may cause stoma holes, and as a
result, the frequency characteristic of the speaker may be disturbed or abnormal noise may be
generated due to the rolling of diaphragm 1. There was a defect such as
OBJECTS OF THE INVENTION The present invention is made to eliminate the above-mentioned
drawbacks of the prior art, and the object of the present invention is therefore to flow the
magnetic fluid sealing the gap to the surface side of the frame etc. There is no slip, there is k to
provide power. SUMMARY OF THE INVENTION In order to achieve the above object, according to
the present invention, a magnetic circuit for holding a magnetic fluid is provided not in the
surface side of the frame but in the back and is integrally fixed to the diaphragm. The outer side
surface and the inner side surface of the magnetic fluid holding magnetic circuit are disposed to
face each other, and the gap is sealed with the magnetic fluid. Then, the gap between the outer
surface of the cylindrical portion and the inner surface of the frame disposed opposite to the gap
is made larger than the gap sealed by the magnetic fluid. DETAILED DESCRIPTION OF THE
PREFERRED EMBODIMENT An embodiment of the present invention will be described below with
reference to the drawings. FIG. 1 is a cross-sectional view showing an embodiment of the present
invention, and FIG. 5 is an enlarged view of a portion A of FIG. In these figures, the same symbols
are attached to the same parts as in the conventional example. In addition, 13 is an outer side
surface of the cylindrical portion 2, 14 is an inner side surface of the frame 7 arranged to face
the outer side surface 13 of the cylindrical portion 2, 1 inner surface of the magnetic circuit 8 for
holding magnetic fluid It is. In this embodiment, as shown in FIG. 3, the space between the outer
surface 13 of the cylindrical portion 2 and the inner side surface 14 of the frame 7 [b is for
holding the magnetic fluid with the outer surface 15 of the cylindrical portion 2 A gap cL
between the inner surface 15 of the magnetic circuit 8 (while being sealed by the magnetic fluid
9, i! i) made larger (ie, 4 <become better). )。 By doing this, even if the speaker is operated,
the magnetic fluid 9 can be pushed out from the gap to the surface 111 J of the diaphragm 1 and
the frame 7 to prevent the flow-out phenomenon. Although the above description has been made
only for the dome-shaped speaker, it is apparent that the implementation of the present
invention is not limited to the dome-shaped speaker. According to the present invention, the
sealing effect by the magnetic fluid between the cylindrical member fixed integrally with the
diaphragm and the frame is further ensured, and the magnetic fluid flows out to the front surface
Wi side of the frame. Also, it is possible to prevent generation of abnormal sound due to rolling
of the diaphragm etc. or disturbance of the frequency characteristic, etc. and there is also an
effect that the surface of the diaphragm and frame is not soiled and the speaker operation
becomes stable. is there.
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[0002]
Brief description of the drawings
[0003]
FIG. 1 is a sectional view showing an embodiment of the present invention, FIG. 2 is a sectional
view showing a conventional speaker, and FIG. 3 is an enlarged view of a portion A of FIG.
Reference Signs 1 · · · dome-shaped diaphragm 2 · · · cylindrical portion 6 · · · adhesive 4 · · · voice
coil 5 · · · spider 6 · · · · spider ring 7 · · · frame 8 · · · magnetic Magnetic circuit for fluid retention
9: Magnetic fluid 1 D: Center pole 11: Yoke plate 12: Magnet 15: Outer surface 14 of the
cylindrical portion 14: Inner surface of the frame
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