Electrical audio signal processing systems and devices – Electro-acoustic audio transducer – Electromagnetic
Reexamination Certificate
2000-07-19
2002-03-19
Tran, Sinh (Department: 2643)
Electrical audio signal processing systems and devices
Electro-acoustic audio transducer
Electromagnetic
C381S402000, C381S412000
Reexamination Certificate
active
06359996
ABSTRACT:
TECHNICAL FIELD
The invention relates to a speaker apparatus and, more particularly, to a speaker apparatus having a primary coil and a secondary coil.
BACKGROUND ART
Hitherto, an electromagnetic induction speaker has been known. As such a speaker, there are what is called an inner magnetic type electromagnetic induction speaker in which a magnet is arranged inside and what is called an outer magnetic type electromagnetic induction speaker in which a magnet is arranged outside.
As shown in
FIG. 1
, an inner magnetic type electromagnetic induction speaker
100
has a yoke
110
, a magnet
120
, and a diaphragm
130
.
The yoke
110
is constructed by integratedly forming: a disk-shaped bottom portion
111
; a peripheral wall portion
112
projected upward from a peripheral edge of the bottom portion
111
; and a ring-shaped annular plate
113
provided at the upper edge of the peripheral wall portion
112
. The cylindrical magnet
120
is attached to the center portion of the upper surface of the bottom portion
111
. The upper surface of the annular plate
113
of the yoke
110
is attached to a frame
140
.
A disk-shaped center plate
150
is attached to the upper surface of the magnet
120
. The center plate
150
is arranged in a center hole
113
a
of the annular plate
113
. A gap formed between the annular plate
113
and center plate
150
is a magnetic gap
160
.
The diaphragm
130
is constructed by integratedly forming: an almost semispherical dome portion
131
provided in the center portion; and an edge portion
132
having a small arc-shaped cross section and formed so as to be continuous with the outer periphery of the dome portion
131
. An outer edge portion of the edge portion
132
is attached to the upper surface of the frame
140
. An upper edge of a cylindrical bobbin
170
is fixed to the outer peripheral edge of the dome portion
131
by adhesion or the like.
A secondary coil
171
of one turn is wound around a portion near the lower edge of the bobbin
170
and fixed. The secondary coil
171
is located in the magnetic gap
160
formed between the annular plate
113
and center plate
150
.
A primary coil
180
on the outer peripheral side and a primary coil
190
on the inner peripheral side are arranged in the magnetic gap
160
so as to face each other through the secondary coil
171
. The outer peripheral side primary coil
180
is fixed to the inner peripheral surface of the annular plate
113
of the yoke
110
. The inner peripheral side primary coil
190
is fixed to the outer peripheral surface of the center plate
150
. The outer peripheral side primary coil
180
and inner peripheral side primary coil
190
are serially connected. One end of the outer peripheral side primary coil
180
is connected to a signal lead wire
180
a.
One end of the inner peripheral side primary coil
190
is connected to a signal lead wire
190
a.
When a current based on an audio signal which is supplied from an audio signal reproducing unit (not shown) is supplied to the outer peripheral side primary coil
180
and inner peripheral side primary coil
190
, an induction current flows in the secondary coil
171
arranged in the magnetic gap
160
. The diaphragm
130
is vibrated by a Lorentz force. The audible sound based on the audio signal corresponding to the current supplied to the primary coil
190
is generated.
As shown in
FIG. 2
, an outer magnetic type speaker
200
comprises a yoke
210
, a magnet
220
, and a diaphragm
230
.
The yoke
210
is constructed by integratedly forming: a disk-shaped bottom portion
211
; and a center pole
212
projected upward from the center portion of the bottom portion
211
. The cylindrical magnet
220
is attached to an outer edge portion of the upper surface of the bottom portion
211
.
A ring-shaped annular plate
240
is attached to the upper surface of the magnet
220
. The annular plate
240
is arranged in correspondence to the upper edge portion of the center pole
212
. An upper surface of the outer edge portion of the annular plate
240
is attached to a frame
250
. A gap formed between the annular plate
240
and center pole
212
is a magnetic gap
260
.
The diaphragm
230
comprises: a center portion
231
having an arc-shaped cross section and locating in the center portion; an inclined portion
232
which is provided so as to be continuous with the outer periphery of the center portion
231
and deviated upward as it approaches the outward position; an edge portion
233
which is continuous with the outer periphery of the inclined portion
232
; and a fixing portion
234
which is provided so as to be continuous with the outer periphery of the center portion
231
and is projected in the direction opposite to the inclined portion
232
. An outer edge portion of the edge portion
233
is attached to the upper surface of the outer edge portion of the frame
250
. An upper edge portion of a cylindrical bobbin
270
is fixed to an edge portion of the fixing portion
234
by adhesion or the like.
A secondary coil
271
of one turn is wound around a portion near the lower edge of the bobbin
270
and fixed. The secondary coil
271
is located in the magnetic gap
260
formed between the annular plate
240
and center pole
212
.
A primary coil
280
on the outer peripheral side and a primary coil
290
on the inner peripheral side are arranged in the magnetic gap
260
so as to face each other through the secondary coil
271
. The outer peripheral side primary coil
280
is fixed to the inner peripheral surface of the annular plate
240
. The inner peripheral side primary coil
290
is fixed to the upper edge portion of the outer peripheral surface of the center pole
212
. The outer peripheral side primary coil
280
and inner peripheral side primary coil
290
are serially connected. One end of the outer peripheral side primary coil
280
is connected to a signal lead wire
280
a.
One end of the inner peripheral side primary coil
290
is connected to a signal lead wire
290
a.
When a current based on an audio signal which is supplied from an audio signal reproducing unit (not shown) is supplied to the outer peripheral side primary coil
280
and inner peripheral side primary coil
290
in a manner similar to the speaker
100
shown in
FIG. 1
mentioned above, an induction current flows in the secondary coil
271
arranged in the magnetic gap
260
. The diaphragm
230
is vibrated by a Lorentz force. The audible sound based on the audio signal corresponding to the supplied current is generated.
When the primary coils
180
,
190
,
280
, and
290
mentioned above are fixed to the annular plates
113
and
240
or the center plate
150
or center pole
212
, there are generally the following two methods.
(1) In a state where the primary coils
180
,
190
,
280
, and
290
are wound and fixed to the outer peripheral surface of the cylindrical bobbin (not shown), they are internally fitted to the annular plates
113
and
240
or externally fitted to the center plate
150
or center pole
212
and fixed by adhesion or the like.
(2) In a state where the primary coils
180
,
190
,
280
, and
290
are wound without using any bobbin (they are formed as bobbinless coils), they are internally fitted to the annular plates
113
and
240
or externally fitted to the center plate
150
or center pole
212
and fixed by adhesion or the like.
Generally, the foregoing bobbins and the primary coils
180
,
190
,
280
, and
290
which are internally fitted to the annular plates
113
and
240
or externally fitted to the center plate
150
or center pole
212
are very thin and their mechanical strengths are weak. Therefore, when they are internally fitted to the annular plates
113
and
240
or externally fitted to the center plate
150
or center pole
212
, it is necessary to prevent the occurrence of damage or the like by constructing them in such a manner that the bobbins and the primary coils
180
,
190
,
280
, and
290
are not come into contact with the annular plates
113
and
240
, center plate
150
, an
Maioli Jay H.
Sony Corporation
Tran Sinh
LandOfFree
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