JP2009147713

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DESCRIPTION JP2009147713
An electromagnetic transducer capable of preventing a diaphragm and a permanent magnet plate
from contacting while maintaining a large amplitude of the diaphragm uniformly. A permanent
magnet plate (2) and (3) on which a strip-like multipolar magnetization pattern is formed, and a
coil pattern (4a) arranged opposite to a surface of the permanent magnet plates (2 and 3) on
which the multipolar magnetization pattern is formed The upper metal frame 11 and the lower
side that cover and support the vibrating film 4 that is electromagnetically coupled to the
permanent magnet plates 2 and 3 and vibrates when a current flows in the coil pattern 4a, and
the permanent magnet plates 2 and 3 and the vibrating film 4 The electromagnetic transducer 1
having the metal frame 12 is provided with the sponge edge 5 for sandwiching and supporting
the outer peripheral portion of the vibrating membrane 4. [Selected figure] Figure 1
Electromagnetic converter
[0001]
The present invention relates to an electromagnetic transducer which has a coil pattern on the
surface of a diaphragm and reproduces sound from an audio signal.
[0002]
Various techniques have been proposed for an electromagnetic transducer in which a permanent
magnet plate and a vibrating membrane are combined.
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1
For example, the electromagnetic converter of Patent Document 1 includes a permanent magnet
plate, a vibrating membrane disposed to face the permanent magnet plate, and a buffer member
disposed between the permanent magnet plate and the vibrating membrane. There is. The
permanent magnet plate has a multi-pole magnetization pattern in which strip-like different
magnetic poles are alternately formed at regular intervals. In the vibrating film, a coil formed of a
meander-shaped conductor pattern is formed on the entire surface at a position facing the socalled neutral zone of magnetization in the gap between different magnetic poles of permanent
magnet plates. When current (audio signal) flows in the coil of the diaphragm, the coil and the
multipolar magnetization pattern of the permanent magnet plate are electromagnetically
coupled, and audio vibration is generated in the diaphragm according to the law of Fleming. The
permanent magnet plate, the diaphragm and the buffer member are covered with a metal frame
and attached to the speaker housing.
[0003]
JP-A-9-331596
[0004]
Since the conventional electromagnetic transducer is configured as described above, it is
necessary to fix and fix a part of the vibrating membrane to the metal frame, and there is a
problem that the amplitude of the vibrating membrane is restricted and it is difficult to make
large amplitude.
In addition, when a part of the diaphragm is attached to the metal frame, the diaphragm vibrates
unevenly when it is oscillated with a large amplitude, and the diaphragm and the permanent
magnet plate come into contact with each other to generate noise. The
[0005]
The present invention has been made to solve the above-described problems. Even when the
amplitude of the vibrating membrane becomes large, the amplitude is kept uniform and the
vibrating membrane and the permanent magnet plate are in contact with each other. It is an
object of the present invention to obtain an electromagnetic converter capable of preventing the
[0006]
The electromagnetic converter according to the present invention has a permanent magnet plate
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on which a strip-shaped multipolar magnetization pattern is formed, and a coil pattern disposed
opposite to the surface on which the multipolar magnetization pattern is formed in the
permanent magnet plate, An electromagnetic transducer comprising: a vibrating film
electromagnetically coupled to the permanent magnet plate and vibrating when a current flows
in a coil pattern; and a frame covering and supporting the permanent magnet plate and the
vibrating film, the vibrating film And a buffer member for sandwiching and supporting the outer
peripheral portion of
[0007]
According to the present invention, since the shock absorbing member for sandwiching and
supporting the outer peripheral portion of the vibrating membrane is provided, it is possible to
make the vibrating membrane have a large amplitude uniformly by the expansion and
contraction of the shock absorbing member, and the vibrating membrane and the permanent
magnet plate It is possible to prevent contact and generation of noise.
[0008]
Embodiment 1
FIG. 1 is an exploded perspective view showing a configuration of an electromagnetic converter
according to Embodiment 1 of the present invention, and FIG. 2 is a cross-sectional view of the
electromagnetic converter of FIG.
The permanent magnet plates 2 and 3 of the electromagnetic converter 1 shown in FIG. 1 have
strip-like multipolar magnetization patterns (parallel stripes of alternating N poles and S poles
appearing on the surface facing the vibrating film 4) A magnetized pattern is formed.
In the vibrating film 4, a coil pattern 4a consisting of a meander-shaped conductive wire pattern
is printed on a thin and flexible film 4b. The linear portion of the coil pattern 4a extending in the
longitudinal direction of the rectangular diaphragm 4 is a position corresponding to a neutral
zone that is approximately halfway between the N pole and the S pole of the upper permanent
magnet plate 2 and the lower permanent magnet plate 3 Provided in When a current flows in the
coil pattern 4 a of the vibrating membrane 4, the permanent magnet plates 2 and 3 are
electromagnetically coupled to vibrate in the thickness direction of the electromagnetic converter
1.
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[0009]
The sponge edge (buffer member) 5 has a rectangular frame shape capable of holding the outer
peripheral portion of the vibrating membrane 4 and is made of, for example, an elastic member
such as urethane foam. As shown in FIG. 2, the pair of sponge edges 5 is disposed between the
upper metal frame 11 in which the upper permanent magnet plate 2 is disposed and the lower
metal frame 12 in which the lower permanent magnet plate 3 is disposed. Since the film 4 is
held, a constant gap can be provided between the upper permanent magnet plate 2 and the
vibrating film 4 and between the lower permanent magnet plate 3 and the vibrating film 4.
Thereby, even when the diaphragm 4 vibrates, generation of noise due to collision between the
upper permanent magnet plate 2 and the diaphragm 4 or the lower permanent magnet plate 3
and the diaphragm 4 is prevented. Can.
[0010]
Furthermore, a plurality of sponge cushions (second buffer members) 6 are disposed in the
vicinity of the center of the vibrating membrane 4 with the vibrating membrane 4 interposed
therebetween, and the sponge cushion 6 pair is an upper permanent magnet plate 2 and a lower
permanent Hold with the magnet plate 3. The sponge cushion 6 is made of, for example, an
elastic member such as urethane foam. Further, the arrangement position and the arrangement
number of the sponge cushions 6 can be set arbitrarily. By interposing the sponge cushion 6
between the upper permanent magnet plate 2 and the vibrating membrane 4 and between the
lower permanent magnet plate 3, nonuniform displacement of the vibrating membrane 4 can be
suppressed.
[0011]
An upper metal on which a pair of sponge edges 5 are disposed so as to sandwich the outer
peripheral portion of the vibrating membrane 4 and a plurality of sponge cushions 6 are
disposed near the center of the vibrating membrane 4 and the upper permanent magnet plate 2
is disposed. The metal frame (frame) 10 is configured by sandwiching and bonding the frame
(frame) 11 and the lower metal frame (frame) 12 in which the lower permanent magnet plate 3 is
disposed. A plurality of radiation sound holes 11 a and 12 a are formed on the surface of the
vibrating film 4 of the upper metal frame 11 and the lower metal frame 12 facing the coil pattern
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4 a.
[0012]
Next, the operation of the electromagnetic converter 1 will be described. Since the vibrating film
4 is disposed opposite to the surface on which the multipolar magnetization pattern is formed in
the permanent magnet plates 2 and 3, when a current as an audio signal flows through the coil
pattern 4a formed on the surface, the coil pattern 4a and the multipolar magnetization pattern of
the permanent magnet plates 2 and 3 are electromagnetically coupled, and audio vibration is
generated in the vibrating film 4 according to Fleming's law. Sound waves generated by the audio
vibration are emitted to the outside through the emission sound holes 11a and 12a, and audio
reproduction is performed.
[0013]
Next, displacement of the diaphragm of the electromagnetic converter according to the first
embodiment will be described. When the vibrating membrane 4 vibrates, the sponge edge 5 for
holding the vibrating membrane 4 is also extended and contracted to be displaced, whereby the
amplitude of the vibrating membrane 4 is allowed. On the other hand, when the amount of
compression of the sponge edge 5 increases, a restoring force for returning the sponge edge 5 to
the original shape is generated, and the vibration film 4 is further suppressed from being
oscillated. As a result, the vibrating membrane 4 can be prevented from coming into contact with
the permanent magnet plates 2 and 3, and generation of abnormal noise can be prevented.
[0014]
FIG. 3 is a view showing another example of the sponge edge of the electromagnetic transducer
in accordance with the first embodiment of the present invention. Another embodiment of the
sponge edge 5 will be described with reference to FIG. FIG. 3A shows a configuration in which
the pair of sponge edges 5 is provided to sandwich and support the outer peripheral portion of
the vibrating membrane 4 over the entire periphery as described above. On the other hand, FIG.
3 (b) shows a configuration in which a pair of sponge edges 5 is provided to sandwich and
support only two opposing sides of the rectangular vibrating film 4 in the short side direction.
Further, FIG. 3C shows a configuration in which a pair of sponge edges 5 is provided which
sandwiches and supports only two opposing sides in the longitudinal direction of the rectangular
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diaphragm 4. Further, FIG. 3D shows a configuration in which a pair of sponge edges 5 for
holding and supporting the four corners of the vibrating membrane 4 is provided.
[0015]
As described above, according to the first embodiment, the sponge edge pair is disposed between
the upper metal frame on which the upper permanent magnet plate is disposed and the lower
metal frame on which the lower permanent magnet plate is disposed to vibrate Since the
membrane is configured to be held, the sponge edge is also displaced at the same time as the
vibrating membrane vibrates, and the amplitude of the vibrating membrane can be allowed
within a certain range. As a result, it is possible to suppress the generation of noise due to the
vibrating film coming into contact with the permanent magnet plate.
[0016]
Further, according to the first embodiment, a plurality of sponge cushions are disposed in the
vicinity of the center of the vibrating film via the vibrating film, and the upper permanent magnet
plate and the lower permanent magnet plate sandwich the sponge cushions. Because of this, it is
possible to suppress uneven displacement of the vibrating membrane.
[0017]
It is a disassembled perspective view which shows the structure of the electromagnetic converter
which concerns on Embodiment 1 of this invention.
It is the sectional view on the AA line in FIG. It is a figure which shows the example of
arrangement ¦ positioning of the sponge edge of the electromagnetic transducer concerning
Embodiment 1 of this invention.
Explanation of sign
[0018]
DESCRIPTION OF SYMBOLS 1 electromagnetic converter, 2, 3 permanent magnet board, 4
vibrating membrane, 4a coil pattern, 4b resin film, 5 sponge edge, 6 sponge cushion, 10 metal
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frame, 11 upper metal frame, 12 lower metal frame, 11a, 12a Sound emission hole.
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