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JPH0898295

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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 JPH0898295
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention cancels out
the leakage flux (leaking magnetism) by the cancel magnet in the external magnetic type
magnetic circuit and further reduces the leakage flux extremely by using the magnetic shield
cover (hereinafter referred to as "magnetic shielding") The present invention relates to a
magnetically shielded speaker such as a cone-shaped speaker designed to be effective.
[0002]
2. Description of the Related Art For example, a cone-shaped magnetically shielded speaker using
an external magnetic circuit as an electrodynamic (dynamic) magnetically shielded speaker is
widely used. This will be specifically described with reference to FIG. 10. In the figure, reference
numeral 1 denotes a cone-shaped magnetically shielded speaker. An iron disk 2 having a
cylindrical center pole 2a protruding from the center of the cone-shaped speaker 1, a disk
annular magnet (permanent magnet) 3 bonded to the upper surface of the yoke 2, and the
magnet An iron-made, disk-shaped plate 4 bonded on the upper side 3 and an outer-magnet-type
magnetic circuit are formed to produce a uniform DC magnetic field. Further, on the lower
surface (bottom surface) of the yoke 2, a cancel magnet 5 is attached which is magnetized so that
the polarity is opposite to the magnetization of the N pole and the S pole of the magnet 3 to
cancel the leakage flux. The yoke 2, the magnet 3 and the plate 4 constituting the magnetic
circuit are covered with a ferrous bottomed cylindrical magnetic shield cover 6 to which the
cancel magnet 5 is bonded and fixed, and among the members constituting the magnetic circuit,
The diameter of the plate 4 is made larger than the diameter of the magnet 3 and the diameter
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smaller than the inner diameter of the magnetic shield cover 6 to reduce the leakage flux (the
magnetic shielding effect is intended).
[0003]
Further, a frame (outer frame) 8 is mounted on the plate 4 via a screw 7 or the like. In the gap
between the center pole 2a of the yoke 2 and the hole 4a of the plate 4, a voice coil 10 is
interposed via a damper 9 fixed to the frame 8. A cone paper (diaphragm) 12 is stretched
between the voice coil 10 and a gasket (arrow sheet) 11 disposed on the outer periphery of the
frame 8, and the voice coil 10 is closed by a cap 13. . Further, a plurality of mounting holes 8 a
are formed in the outer peripheral portion of the frame 8. When an AC voltage (signal) is applied
to the boil coil 10 inserted in the gap between the center pole 2a of the yoke 2 and the hole 4a of
the plate 4 constituting the magnetic circuit, a cone according to Fleming's left hand law The
paper 12 vibrates under the force. In FIG. 10, 14 is a pair of (+,-) lead wires, and 15 is an input
terminal.
[0004]
However, in the above-mentioned conventional cone-shaped magnetic shield speaker 1, the plate
4 and the magnetic shield cover 6 constituting the external magnetic magnetic circuit are
concentrically fixed and fixed. However, it is very difficult because the magnet 3 is magnetized,
and as shown in FIG. 10, one side of the plate 4 is in contact with the inner peripheral surface of
the magnetic shield cover 6 and the other side is separated and eccentric. Was easy to assemble.
For this reason, the gap between the outer peripheral surface of the plate 4 and the inner
peripheral surface of the magnetic shield cover 6 is not uniform around the plate 4 and the force
to cancel and reduce the leakage flux around the magnetic shield cover 6 is uneven. As a result,
there is a drawback that the mounting of the speaker 1 has directivity. Further, since there are
four mounting holes 8a at every 90 ° on the outer side of the frame 8 of the speaker 1, it has
been difficult to make the magnetic shielding effect uniform for all the mounting holes 8a. That
is, the magnetic shielding effect is in a directional state on the outer periphery of the magnetic
shield cover 6, and the leakage flux can not be reduced uniformly and reliably.
[0005]
Therefore, according to the present invention, the gap between the plate or the like forming the
magnetic circuit and the magnetic shield cover is made uniform (uniform) so that the magnetic
shielding effect can be easily and surely made uniform on the outer periphery of the magnetic
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shield cover. To provide a magnetically shielded speaker that can
[0006]
A magnetic circuit comprising a yoke, a magnet and a plate for producing a magnetic field, and a
voice coil placed in the magnetic circuit for producing a force proportional to an audio current A
magnetic shield speaker comprising: a diaphragm transmitting the vibration of the voice coil to
the air; a cancel magnet attached to the yoke to cancel a leakage magnetic flux; and a magnetic
shield cover covering the magnetic circuit and the cancel magnet; At least one of the yoke and
the plate of the circuit and the magnetic shield cover is provided with positioning means for
centering the magnetic circuit in the magnetic shield cover.
[0007]
The plate or the like constituting the magnetic circuit is easily and reliably disposed at the center
of the magnetic shield cover by the positioning means.
Thereby, the plate etc. which comprises a magnetic circuit and a magnetic shield cover are
arrange | positioned concentrically, and a magnetic-shielding effect tends to become uniform
uniformly in the outer periphery of a magnetic shield cover.
[0008]
Embodiments of the present invention will now be described in detail with reference to the
drawings.
The same components as those of the conventional example shown in FIG.
[0009]
In FIG. 1, reference numeral 1 denotes a cone-shaped magnetically shielded speaker, which is
constituted by a yoke 2 and a magnet 3 and a plate 4 to form a magnetic circuit so that a uniform
DC magnetic field can be produced. The magnet has a bottom surface with a cylindrical magnetic
shield cover 6 that covers the yoke 2, the magnet 3, the plate 4, and the cancel magnet 5
constituting the magnetic circuit. Point, the diameter of the plate 4 is made larger than the
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diameter of the magnet 3 and the diameter of the plate 4 is made smaller than the inner diameter
of the magnetic shield cover 6 to achieve a magnetic shielding effect, the center of the yoke 2
constituting the magnetic circuit The voice coil 10 is inserted in the gap between the pole 2a and
the hole 4a of the plate 4; Point or the like is attached to the cone paper (vibration plate) 12 on
an outer peripheral portion of the 8 via a gasket (arrows paper) 11 and the like are the same as
the conventional configuration.
[0010]
Here, as shown in FIG. 2, on the outer peripheral surface of the plate 4, it is in contact with the
inner peripheral surface of the magnetic shield cover 6 to arrange the plate 4 and the magnetic
shield cover 6 concentrically. A triangular protrusion (positioning means) 4b is integrally formed
at an interval of 120 °.
In addition, in FIG. 2, although three protrusion 4b is formed, three or more may be sufficient.
[0011]
A method of assembling the cone-shaped speaker 1 of the embodiment will be described in order
along FIGS. First, as shown in FIG. 3, the disk-shaped magnet 3 is adhered and fixed to the upper
surface of a disk-shaped yoke 2 in which a cylindrical center pole portion 2a is protruded at the
center. In this case, a spacer or the like (not shown) is inserted into the center pole portion 2a of
the yoke 2 so that the magnet 3 is bonded and fixed concentrically to the yoke 2.
[0012]
Next, the disk-shaped plate 4 is adhered and fixed onto the magnet 3 by an adhesive. In this case,
there is a gap in which the voice coil 10 is inserted between the center pole 2a of the yoke 2 and
the hole 4a of the plate 4. In order to make this gap a concentric space, as shown in FIG. The gap
guide 20 is put in the gap, and the adhesive is dried and adhesively fixed. After this fixing, the
gap guide 20 is removed. Thereafter, if the frame 8 is attached to the plate 8 via the screw 7 or
the like, the speaker 1 can be assembled.
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[0013]
Next, as shown in FIG. 5, the voice coil 10 is fixed concentrically on each member at a
predetermined position of the gap formed between the center pole 2a of the yoke 2 and the hole
4a of the plate 4. Do. In this case, the voice coil spacer 21 is inserted inside the voice coil 10, and
is inserted into the center pole portion 2a of the yoke 2 as it is. Thereafter, the outer peripheral
portion of the damper 9 is bonded and fixed to the frame 8 with an adhesive, and the inner
peripheral portion of the damper 9 is bonded and fixed to the outer diameter portion of the voice
coil 10 by an adhesive. The outer peripheral portion of the edged cone paper 12 is adhered and
fixed to the upper surface of the outer peripheral portion of the frame 8 with an adhesive via a
gasket 11 or the like, and the inner peripheral portion of the cone paper 12 is the outer diameter
of the voice coil 10 Adhesively fix to the part with adhesive. After drying and fixing each of these
adhesives, the voice coil spacer 21 is removed, and as shown in FIG. 1, the cap 13 is attached to
the inner peripheral portion of the cone paper 12 and the magnet 3 is magnetized. Do.
[0014]
Next, the cancel magnet 5 is bonded and fixed to the bottom of the bottomed cylindrical
magnetic shield cover 6 so that the polarity of the N pole and the S pole is opposite to that of the
magnet 3. Magnetize Next, an adhesive is applied to the upper surface of the cancel magnet 5,
and the cancel magnet 5 is adhered and fixed to the lower surface (bottom surface) of the yoke 2.
At this time, the projections 4b protruding from the outer peripheral surface of the plate 4 are in
contact with the inner peripheral surface of the magnetic shield cover 6, and the plate 4 and the
magnetic shield cover 6 are arranged concentrically, that is, with the outer peripheral surface of
the plate 4. The gap formed between the magnetic shield cover 6 and the inner circumferential
surface of the magnetic shield cover 6 is concentric, and the magnetic shielding effect is also
uniform on the outer periphery of the magnetic shield cover 6, and the initial target is achieved.
[0015]
As described above, three projections 4b for positioning with respect to the magnetic shield
cover 6 are integrally formed on the outer peripheral surface of the plate 4 so that the center of
the plate 4 and the center of the magnetic shield cover 6 coincide with each other as in the prior
art. Since there is no bias, even if the magnet 3 is magnetized, all of the yoke 2, the magnet 3 and
the plate 4 constituting the magnetic circuit with respect to the magnetic shield cover 6 can be at
the center of the magnetic shield cover 6, Concentricity can be fixed easily and reliably. Thereby,
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as shown in FIG. 1, the gap between the outer peripheral surface of the plate 4 and the inner
peripheral surface of the magnetic shield cover 6 can be made uniform (uniform), and the
magnetic shielding effect is biased as in the prior art Absent. As a result, there is no directivity in
attaching the cone-shaped magnetically shielded speaker 1, and the magnetic shielding effect is
also achieved for each mounting hole 8a formed four at every 90 ° on the outer side of the
frame 8 of the speaker 1. Can always be uniform. That is, the magnetic shield effect is in a nondirectional state, and the leakage magnetic flux can be reliably canceled on the outer periphery
of the magnetic shield cover 6 so that a uniform and strong direct current magnetic field can be
always formed.
[0016]
6 and 7 show another embodiment. In FIG. 6, 1 'is a cone-shaped speaker (magnetic shield
speaker). In the cone-shaped speaker 1 shown in FIG. 1, the projections 4b as positioning means
are formed on the outer peripheral surface of the plate 4. However, in the cone-shaped speaker 1
'of the other embodiment, the yoke 2' having the center pole portion 2a. The difference is that
projections 2b as positioning means are integrally formed on the outer peripheral surface of the
speaker, and the other configuration is the same as that of the cone-shaped speaker 1 shown in
FIG. As a result, the same operation and effect as the embodiment shown in FIGS. 1 and 2 can be
obtained.
[0017]
8 and 9 show another embodiment. In FIG. 8, 1 '' is a cone-shaped speaker (magnetic shield
speaker). In the cone-shaped speaker 1 shown in FIG. 1, the projections 4b as positioning means
are formed on the outer peripheral surface of the plate 4. However, in the cone-shaped speaker 1
′ ′ of this another embodiment, positioning is performed on the periphery of the magnetic
shield cover 6 ′ ′. The difference is that the concave portion 6b as a means is integrally
formed so as to protrude on the inner peripheral surface side, and the other configuration is the
same as that of the cone-shaped speaker 1 shown in FIG. As a result, each concave portion 6b
inside the cylindrical portion of the magnetic shield cover 6 '' is in contact with the outer
peripheral surface of the plate 4, and concentric circles between the outer peripheral surface of
the plate 4 and the inner peripheral surface of the magnetic shield cover 6 '' can be taken Thus,
the same operation and effect as the embodiment shown in FIGS. 1 and 2 can be obtained.
[0018]
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Although three positioning means are provided at intervals of 120 ° in each of the above
embodiments, three or more positioning means may be provided. Also, although a cone-shaped
speaker has been described as a dynamic type magnetically shielded speaker, it goes without
saying that the above embodiments can be applied to other direct radiation type speakers such
as a dome shape and a ribbon shape.
[0019]
As described above, according to the present invention, a magnetic circuit which is made up of a
yoke, a magnet and a plate to produce a magnetic field, and which is placed in the magnetic
circuit and is proportional to an audio current A voice coil for generating force, a diaphragm for
transmitting the vibration of the voice coil to the air, a cancel magnet attached to the yoke to
cancel the leakage flux, and a magnetic shield cover covering the magnetic circuit and the cancel
magnet In the magnetic shield speaker, since at least one of the yoke and the plate of the
magnetic circuit and the magnetic shield cover is provided with positioning means for arranging
the magnetic circuit at the center of the magnetic shield cover Plates etc. that make up the circuit
can be easily located in the center of the magnetic shield cover via the positioning means One
can be reliably arranged. As a result, the plate etc. constituting the magnetic circuit and the
magnetic shield cover can be arranged concentrically and easily concentrically, and an excellent
effect can be obtained in which the magnetic shielding effect can be easily made uniform over
the entire circumference of the magnetic shield cover. It is a thing.
[0020]
Brief description of the drawings
[0021]
1 is a cross-sectional view showing a cone-shaped magnetically shielded speaker according to an
embodiment of the present invention.
[0022]
2 is a perspective view of a plate used for the magnetically shielded speaker of the above
embodiment.
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[0023]
3 is a cross-sectional view showing an assembled state of the yoke and the magnet used for the
magnetically shielded speaker of the above embodiment.
[0024]
4 is a cross-sectional view showing the plate and the frame assembled on the assembled magnet.
[0025]
5 is a cross-sectional view showing a state in which corn paper and the like are assembled on the
assembled frame.
[0026]
6 is a cross-sectional view showing a cone-shaped magnetically shielded speaker according to
another embodiment of the present invention.
[0027]
7 is a perspective view of a yoke used in the magnetic shield speaker of the other embodiment.
[0028]
8 is a sectional view showing a cone-shaped magnetically shielded speaker according to another
embodiment of the present invention.
[0029]
FIG. 9 is a perspective view of a magnetic shield cover used in the magnetic shield speaker of the
other embodiment.
[0030]
10 is a cross-sectional view showing a conventional cone-shaped magnetically shielded speaker.
[0031]
Explanation of sign
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[0032]
1, 1 ', 1 "... Magnetic shield speaker 2, 2' ... Yoke 2b ... Protrusion (positioning means) 3 ... Magnet
4 ... Plate 4b ... Protrusion (positioning means) 5 ... Cancel magnet 6, 6" ′ ... Magnetic shield
cover 6b ... recessed part (positioning means) 10 ... voice coil 12 ... cone paper (diaphragm)
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