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DESCRIPTION JP2006333391

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DESCRIPTION JP2006333391
An electromagnetic transducer capable of preventing air leakage from the inside to suppress
abnormal noise and improving the sound pressure drop of an audio signal even in a low band,
and an acoustic device using the same. A lower permanent magnet plate 11 in which strip-like
different magnetic poles are alternately formed at a constant interval. 2) The lower permanent
magnet plate 11 is disposed opposite to the lower permanent magnet plate 11 via the buffer
member 13, and a meandering coil pattern 15b is formed on the surface of the thin and flexible
resin film 15a at a position corresponding to the neutral zone nz in the lower permanent magnet
plate 11. The vibrating membrane 15. 3) An upper permanent magnet plate 17 disposed
opposite to the vibrating membrane 15 via the buffer member 13. 4) A frame 30 in which a
plate-like first support member 31 on which a structure obtained by stacking the above 1) to 3)
is placed and a second support member 33 covering the upper side and the periphery of the
structure are bonded. 5) A first seal member 40 for sealing the gap between the first and second
support members 31 and 33. Also, an acoustic device 60 in which the electromagnetic converter
10 is installed in the speaker housing 50. [Selected figure] Figure 2
Electromagnetic converter and acoustic device using the same
[0001]
The present invention relates to, for example, an electromagnetic converter that reproduces an
audio signal and an acoustic device using the same.
[0002]
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1
Various techniques have been proposed for an electromagnetic transducer combining a
permanent magnet and a vibrating membrane.
An electromagnetic transducer of this type usually comprises 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 is formed by alternately forming strip-like different magnetic poles at
regular intervals (hereinafter, this parallel stripe-shaped magnetization pattern is also referred to
as a multi-pole magnetization pattern). In addition, the vibrating film is disposed opposite to the
formation surface of the multipolar magnetization pattern, and is formed of a meander-shaped
conductor pattern at a position facing the so-called neutral zone of magnetization in the gap
between different magnetic poles. A coil is formed on the entire surface. A plurality of sound
radiation holes for emitting the generated sound waves to the outside are formed at a constant
pitch in the gap between the strip-like different magnetic poles of the above-mentioned
permanent magnet plate (see, for example, Patent Document 1) .
[0003]
The above-described structure in which the permanent magnet plate, the diaphragm, and the
buffer member are stacked is covered by a frame and then attached to, for example, a housing
for an acoustic device, and used as an acoustic device that reproduces audio signals. The frame is
configured by pasting a plate-like support member placed under the above-mentioned structure
and a support member covering the upper side and the periphery of the above-mentioned
structure. Here, a structure in which the above-described structure is covered with a frame is
referred to as an electromagnetic transducer, and a structure in which the electromagnetic
transducer is attached to a housing for an acoustic device such as a speaker is referred to as an
acoustic device.
[0004]
JP-A-9-331596
[0005]
The conventional electromagnetic transducer is configured as described above, and there is a
slight gap at the boundary between the two support members in the frame.
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2
Therefore, when the acoustic device is configured and operated using the electromagnetic
converter, the air inside the electromagnetic converter leaks from the gap of the frame to the
outside. In detail, in the above-mentioned operation, the sound wave due to the amplitude of the
vibration in the speaker portion of the sound device is directed from the inside of the sound
device to the speaker portion if the sound wave heading upward (vertically upward) from the
speaker portion The sound waves are in the reverse phase, and the sound waves in the reverse
phase leak to the upper side through the gap between the two support members described
above. The air (sound wave) leaked to the outside interferes with the sound wave of the positive
phase, and may cancel the positive phase to cause a reduction in sound pressure. Such a
reduction in sound pressure refers to a low frequency band (here, a band of 200 Hz or less). The
lower the straightness of the sound wave, the more pronounced it is. Therefore, there is a
problem that it is not possible to generate noise or decrease the sound pressure in the
electromagnetic converter.
[0006]
The present invention has been made to solve the problems as described above, and is provided
with a sealing material for sealing a gap between boundary portions of two members constituting
a frame of an electromagnetic converter, so that air from the inside can be obtained. An
electromagnetic transducer capable of preventing leakage and suppressing abnormal noise and
improving the sound pressure drop of an audio signal even in a low band, and an acoustic device
using the same.
[0007]
An electromagnetic converter according to the present invention includes the following 1) to 5).
1) A permanent magnet plate in which strip-like different magnetic poles are alternately formed
at a constant interval. 2) A vibrating film in which a coil having a meander-shaped conductor
pattern is formed on the entire surface at a position opposite to a permanent magnet plate and
facing a gap between different magnetic poles of the permanent magnet plate. 3) A buffer
member disposed between the permanent magnet plate and the vibrating membrane. 4) A frame
in which a plate-like first support member on which the above 1) to 3) stacked structure is placed
and a second support member covering the upper side and the periphery of the structure are
attached. 5) A first sealing material for sealing the gap between the first and second support
members.
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[0008]
An acoustic device according to the present invention is provided with an electromagnetic
transducer consisting of the above 1) to 5) and a case for the acoustic device in which the
electromagnetic transducer is installed.
[0009]
According to this invention, the plate-like first support member on which the structure in which
the permanent magnet plate, the vibrating membrane and the buffer member are stacked is
placed, and the second support member covering the upper side and the periphery of the
structure Since the electromagnetic converter is configured to include the first seal material that
covers the outer periphery of the boundary of the first and second support members of the
bonded frame, air leakage from the inside is prevented and noise is generated. It is possible to
obtain an electromagnetic converter capable of reducing the sound pressure drop of the audio
signal even in a low band and an acoustic device using the same.
[0010]
Hereinafter, various embodiments of the present invention will be described.
Embodiment 1
FIG. 1 is an exploded perspective view for explaining a configuration of an electromagnetic
converter according to Embodiment 1 of the present invention, and FIG. 2 is a cross-sectional
view of the entire acoustic device including the electromagnetic converter. It is cut along the line
passing through the sound emission hole. FIG. 3 is an enlarged view of a portion indicated by a
dotted circle in FIG. 2 and shows the vicinity of the boundary between the frame of the
electromagnetic converter and the speaker housing sealed by the first and second sealing
materials. It is In the cross sectional view, hatching indicating a cross section is partially omitted.
Here, one diaphragm is sandwiched by two permanent magnet plates from above and below via a
buffer member. Also, here, a permanent magnet plate in which a sound radiation hole for
radiating a sound wave to the outside is formed is referred to as an upper permanent magnet
plate, and a lower permanent magnet plate is opposed to the upper permanent magnet plate via a
vibrating film. It is conveniently referred to as the side permanent magnet plate.
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[0011]
In the figure, in the lower permanent magnet plate 11, strip-like different magnetic poles (N pole,
S pole) made of sintered ferrite magnets are alternately arranged at a predetermined interval on
almost the entire surface opposite to a vibrating film 13 described later. It is formed (Hereinafter,
this parallel stripe-shaped magnetization pattern is also called a multipolar magnetization
pattern.). A so-called neutral zone nz of magnetization exists in the gap between the different
magnetic poles (N and S poles).
[0012]
A vibrating film 15 is disposed on the upper side of the lower permanent magnet plate 11 at a
position opposite to the surface on which the multipolar magnetization pattern is formed, with
the buffer member 13 interposed. The vibrating film 15 is also referred to as a coil (hereinafter,
also referred to as a meandering coil pattern) formed of a meandering conductor pattern on the
entire surface of the thin and flexible resin film 15a. ) 15b is formed. Each of the linear portions
in the longitudinal direction of the serpentine coil pattern 15b is provided at a position
corresponding to the neutral zone nz in the gap between the different magnetic poles (N and S
poles) of the lower permanent magnet plate 11 There is. The straight portion refers to a long
straight portion of the coil 15b, which is disposed in parallel to each other with a constant
distance. An upper permanent magnet plate 17 is disposed on the upper side of the vibrating
membrane 15 with a band-shaped multipolar magnetized pattern of sintered ferrite magnet
formed on almost the entire surface facing the vibrating membrane 15 with the buffer member
13 interposed therebetween. It is done. The upper permanent magnet plate 17 is provided with
sound emission holes 17a at a constant pitch along the neutral zone nz of the gap between the
magnetic poles (N pole, S pole) having different multipolar magnetization patterns.
[0013]
A plate-like first support member having the structure 20 mounted on the lower side of the
structure 20 on which the lower permanent magnet plate 11, the buffer member 13, the
diaphragm 15, and the upper permanent magnet plate 17 are stacked. A frame 30 is configured
by bonding 31 and a second support member 33 covering the upper side and the periphery of
the structure 20. A sound emission hole 33a is provided corresponding to the position of the
second support member 33 of the frame 30 covering the upper side of the structure 20, at which
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the sound emission hole 17a is formed. There is a gap at the boundary A of the first and second
support members 31 and 33 of the frame 30 configured as described above. A first seal member
40 covers the periphery of the boundary A of the first and second support members 31 and 33
so as to seal the gap of the boundary A.
[0014]
As the first seal member 40, for example, a foamed resin material is suitable. Here, tape-like PEF
(polyethylene foam) was used. PEF is a material that provides excellent air tightness by
compression. Since it can be freely bent, it can be attached according to the frame shape, and is
suitable as a sealing material. Further, the tape-like PEF used here is one in which an adhesive
tape is attached to one side of the PEF material, and the workability is good.
[0015]
The acoustic device 60 is configured by installing the electromagnetic converter 10 configured
as described above in the speaker casing (the casing for the acoustic device) 50. In the acoustic
device 60, the gap at the boundary B between the frame 30 and the speaker housing 50 is sealed
by the second seal member 51. This prevents air from leaking from the inside of the speaker
housing 50 to the outside through the gap at the boundary B. Here, the second seal member 51
is stacked and attached to the first seal member 40 so as to fill the gap between the frame 30 of
the electromagnetic converter 10 and the speaker housing 50. Here, a tape-like PEF was used as
the second sealing material 51 as well.
[0016]
Next, the operation will be described. When an electric current as an audio signal flows through
the meandering coil pattern 15b formed on the surface of the vibrating membrane 15, the
meandering coil pattern 15b and the lower and upper permanent magnet plates 11 and 17
disposed opposite to the meandering coil pattern 15b The pole magnetized pattern is
electromagnetically coupled, and the vibrating film 15 vibrates in the thickness direction
according to Fleming's left-hand rule, and a sound wave generated by this vibration is radiated
into the air through the sound radiation holes 15a and 33a. Ru. At this time, the first seal
member 40 leaks the sound wave due to the vibration generated from the inside of the
electromagnetic converter 10 to the outside through the gap at the boundary A of the first and
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second support members 31 and 33 in the frame 30. prevent. Similarly, the second seal member
51 prevents air generated from the inside of the speaker housing 50 from leaking to the outside
through the gap at the boundary B between the frame 30 and the speaker housing 50.
[0017]
As described above, according to the electromagnetic converter 10 of the first embodiment of the
present invention, the first seal member 40 covering the outer periphery of the boundary A
portion of the two support members 31 and 33 constituting the frame 30 is used. Since it is
provided, air from the inside of the electromagnetic converter 10 is prevented from leaking to
the outside through the gap at the boundary A. Therefore, it is possible to suppress the
generation of abnormal noise in the electromagnetic converter 10 and to prevent the sound
pressure of the audio signal from being lowered even in the low band. Further, according to the
acoustic device 60 of the first embodiment of the present invention, since the electromagnetic
converter 10 of the first embodiment is installed in the speaker housing 50, generation of
abnormal noise in the acoustic device 60 And the possibility of a drop in sound pressure can be
reduced. Furthermore, according to the acoustic device 60 of the first embodiment of the present
invention, the gap at the boundary B between the frame 30 of the electromagnetic transducer 10
and the speaker casing (the casing for the acoustic device) 50 to which the electromagnetic
transducer 10 is attached Since the second seal member 51 to be sealed is provided, air leakage
from the inside of the speaker housing 50 is prevented to suppress abnormal noise, and the
sound pressure drop of the low band audio signal in the electromagnetic converter 10 is further
enhanced. Can be improved.
[0018]
Although Embodiment 1 shows an example in which PEF is used as each of the first sealing
material 40 and the second sealing material 51, the material is not limited to this, and silicone
rubber may be used. As an example, in the case of using a silicone sealant, this material is in the
form of a liquid, and has the advantage that it can be easily sealed in a fine gap. In addition, as
long as it fulfills the function as the first and second sealing materials and exhibits the same
effect, it is not limited to these materials.
[0019]
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FIG. 1 is an exploded perspective view showing a configuration of an electromagnetic converter
of a first embodiment. FIG. 1 is a cross-sectional view showing a configuration of an acoustic
device including the electromagnetic converter according to Embodiment 1. FIG. 3 is an enlarged
cross-sectional view showing the vicinity of a boundary between a frame and a speaker casing of
the acoustic device of the first embodiment.
Explanation of sign
[0020]
DESCRIPTION OF SYMBOLS 10 electromagnetic converter, 11 lower permanent magnet board,
13 buffer member, 15 diaphragm, 15a resin film, 15b coil which consists of a conductor pattern
of a meander shape, 17 upper permanent magnet board, 17a sound radiation hole, 20 structure,
30 Frame, 31 first support member, 33 second support member, 33a sound radiation hole, 40
first seal member, 50 speaker housing, 51 second seal member, 60 acoustic device, nz neutral
zone, A The boundary between the first support member and the second member, the boundary
between the B frame and the speaker housing.
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