JP2011171780

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DESCRIPTION JP2011171780
An electromagnetic converter is provided which suppresses abnormal noise due to divided
vibration of a vibrating membrane. SOLUTION: A permanent magnet disposed on different
magnetic poles alternately at a predetermined interval, and a meander-shaped conductor coil
disposed on a thin film resin surface disposed opposite to the permanent magnet, the conductor
coil And a frame supporting the permanent magnet and the vibrating film so as to cover the
permanent magnet and the vibrating film, and the vibrating film is divided so as to divide the
surface thereof. It is supported by the frame through the attached tape. [Selected figure] Figure 1
Electromagnetic converter
[0001]
The present invention relates to an electromagnetic converter that performs sound reproduction
from an audio signal by combining a permanent magnet and a diaphragm.
[0002]
In a rectangular electromagnetic transducer using a permanent magnet plate and a vibrating
membrane, the permanent magnet plate and the vibrating membrane are disposed to face each
other, and a buffer material is disposed between the permanent magnet plate and the vibrating
membrane. There is something.
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The permanent magnet plate, the vibrating membrane, and the buffer member are covered so as
to be sandwiched by members such as a frame and attached to, for example, a speaker housing.
The above-mentioned permanent magnet plate has strip-like magnetized portions (also referred
to as multipolar magnetized patterns) alternately made into different polarities at regular
intervals. In addition, the vibrating film is a meandering conductor pattern (serpentine coil) that
acts as an electromagnetic coil, facing a position facing a gap at a boundary of different polarity
of the permanent magnet plate, a portion called a so-called magnetized neutral zone ) Is provided
on the surface of the vibrating film. When the current of the audio signal flows through the
meandering coil pattern formed on the vibrating membrane, the meandering coil pattern and the
multipolar magnetization pattern of the permanent magnet plate are electromagnetically
coupled, and the above meandering coil pattern is formed according to Fleming's law. The
vibrating membrane vibrates by acting. Sound waves generated by this vibration are emitted
through a sound hole formed in a permanent magnet plate and a frame to perform audio
reproduction (see, for example, Patent Document 1). Moreover, in order to prevent the conductor
coil formed on the vibrating membrane from breaking due to metal fatigue due to such vibration,
a stiffening member is provided on the vibrating membrane (see, for example, Patent Document
2). In addition, there has conventionally been an ultra-thin speaker called "gamouson type",
which has a configuration similar to that of the above-described electromagnetic converter and is
replaced with the above-mentioned permanent magnet plate and has a rod-like magnet
configuration. The same poles of the rod-like magnet are made to face each other (N and N poles,
or S and S poles), and different polarities are alternately arranged in the direction of arrangement
perpendicular to the rod-like magnets. It consists of the same as above. Such an ultra thin
speaker has a diaphragm formed by attaching copper or aluminum foil to a thin film made of
polyester or polyimide and etching a voice coil pattern (see, for example, Non-Patent Document
1) ). According to this configuration, the sound generation operation of audio reproduction is also
the same as the above-described electromagnetic converter.
[0003]
Patent No. 3192372 gazette Takeo Yamamoto ed., Speaker system, Radio Technology Co., Ltd.,
July 1977 issue
[0004]
In any of the above-described electromagnetic transducers, the vibrating film is an
electromagnetic transducer of a full drive system in which the driving force by the meandering
coil pattern is uniformly generated on the vibrating surface.
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In other words, the vibration film serves as a piston sound source to realize an electromagnetic
converter exhibiting flat sound pressure frequency characteristics. However, in practice, it is
difficult for the vibrating membrane to generate a uniform driving force over the entire band to
cause piston vibration, and in particular, as the aspect ratio of the vibrating membrane is
increased, the vibrating membrane is likely to generate divided vibrations, As shown in FIGS. 7
(a) and 7 (b), there has been a problem that the partial large amplitude of the divided vibration of
the vibrating membrane causes contact with the magnet to generate noise. In addition, there is a
problem that the sound pressure frequency characteristic is disturbed by the divided vibration of
the vibrating film and the sound pressure is deteriorated.
[0005]
The present invention has been made to solve the above-described problems, and an object of the
present invention is to provide an electromagnetic transducer having flat sound pressure
frequency characteristics by suppressing divided vibration of a vibrating film.
[0006]
In the electromagnetic converter according to the present invention, permanent magnets
disposed on different magnetic poles alternately at predetermined intervals, and permanent
magnets disposed opposite to the permanent magnets, meander-shaped conductor coils are
formed on a thin film resin surface And a vibrating membrane that is electromagnetically coupled
to the permanent magnet by energizing the conductor coil and vibrates in the thickness direction,
and a frame that supports the permanent magnet and the vibrating membrane so as to cover the
vibrating membrane. It is supported by the above-mentioned frame via a tape attached to be
divided.
[0007]
According to the electromagnetic converter of the present invention, the vibrating membrane is
supported via the tape attached so as to divide the surface of the vibrating membrane at the
portion corresponding to the antinode of the divided vibration of the vibrating membrane. While
being able to control the division vibration of the vibrating membrane, it is possible to flatten and
stabilize the sound pressure frequency characteristic.
[0008]
Hereinafter, embodiments of the present invention will be described in detail with reference to
the drawings.
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Embodiment 1
FIG. 1 is a view showing the configuration of the electromagnetic converter 10 of the present
invention, and FIG. 1 (a) is an overall perspective view showing the appearance of the
electromagnetic converter 10, and FIG. 1 (b) is a configuration of the electromagnetic converter
10. It is a disassembled perspective view shown.
FIG. 2 is a view showing the structure of the electromagnetic converter 10 of the first
embodiment, and FIG. 2 (a) is a cross-sectional view taken along the line AA of FIG. It is a BB
sectional drawing of a).
[0009]
The electromagnetic transducer 10 is composed of the vibrating membrane 11, the tape 12, the
permanent magnets 21, 22 and the frame 30, and the upper frame 31 and the lower frame 32 of
the frame 30 are lower than the vibrating membrane 11 and the upper permanent magnet 21. It
is comprised so that the side permanent magnet 22 may be covered.
[0010]
The vibrating film 11 is composed of a base material 11a made of a thin polymer resin sheet, and
a conductor coil 11b formed in a meandering shape on the surface of the base material 11a, and
the conductor coil (coil) 11b made of a meander pattern is It is formed by punching a metal foil
by pressing or etching.
[0011]
The tape 12 is a high heat resistant nonwoven fabric and is longer than the width of the vibrating
membrane 11.
The tape 12 is adhered by an adhesive so as to divide the longitudinal direction of the surface of
the vibrating membrane 11, and supports so that both ends of the tape 12 which protrude from
both sides of the vibrating membrane 11 are sandwiched by the frame 30. It is configured.
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[0012]
In the permanent magnets 21 and 22, the strip-like permanent magnets 21 and 22 which are
magnetized are alternately arranged with different magnetic poles, and a predetermined distance
is provided on the surface of the frame 30 facing the vibrating film 11 with an adhesive or the
like. It is fixed.
[0013]
The frame 30 is a rod structure having the inside of a cavity, and the joint surface of the upper
frame 31 and the lower frame 32 sandwiches and supports a part of the tape 12 projecting from
both sides of the vibrating membrane 11.
Band-like permanent magnets 21 and 22 are fixed at predetermined intervals on the surface
facing the vibrating film 11, and circular sound release holes 31 a opened to the outside at
predetermined intervals of the permanent magnets 21 and 22. , 32a are provided at regular
intervals.
[0014]
Here, the relationship between the conductor coil 11b of the diaphragm 11 and the permanent
magnets 21 and 22 is formed such that the conductor coil 11b is disposed at a position opposed
to the predetermined interval of the permanent magnets 21 and 22 fixed to the frame 30. It is
done.
In addition, the tape 12 bonded to the vibrating membrane 11 supports an electromagnetic
converter having any characteristics such as suppressing the maximum amplitude by supporting
the antinode portion where the amplitude of the divided vibration of the vibrating membrane 11
is maximum. The attachment position is determined depending on the design, and the tape 12 in
the first embodiment is assumed to be divided vibration for two wavelengths in which the
vibrating film 11 does not contact the permanent magnets 21 and 22. It is set as the structure
supported by the flame ¦ frame 30 at ten places using the tape 12 of a sheet.
[0015]
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Next, the operation will be described. FIG. 3 is a diagram showing the operation of the
electromagnetic converter 10 of the first embodiment. FIG. 4 is a measurement diagram of
frequency (Hz) -sound pressure level (dB) comparing sound pressure frequency characteristics of
the electromagnetic converter 10 of the first embodiment and the conventional electromagnetic
converter. FIG. 7 is a view showing divided vibration of the conventional electromagnetic
converter 110, and FIG. 7 (a) is a vibration state in the case where the divided vibration of the
vibrating film 111 is a half wavelength, and FIG. 7 (b) is a vibration. FIG. 7C shows the vibration
state when the divided vibration of the film 111 is one wavelength, and FIG. 7C shows the
vibration state when the divided vibration of the vibrating film 111 is 3/2 wavelength.
[0016]
In the conventional electromagnetic transducer 110, as the aspect ratio of the vibrating
membrane 111 increases, for example, as shown in FIGS. 7A to 7C, the vibrating membrane 111
is likely to be divided and vibrated, and a partial large amplitude is generated. Was generating
noise on the permanent magnets 21 and 22. Further, as shown in FIG. 4, the sound pressure
frequency characteristics are disturbed by the divided vibration.
[0017]
In the electromagnetic converter 10 of the first embodiment, by adopting the above
configuration, the vibrating membrane 11 is supported so as to be sandwiched by the frame 30
via both ends of the tape 12, and the large amplitude of the vibrating membrane 11 is obtained.
Generate audio oscillations with multiple amplitudes suppressed. Since a plurality of amplitudes
are not in contact with the permanent magnets 21 and 22, noise does not occur, and the sound
pressure frequency characteristics become flat and stable.
[0018]
As described above, according to the electromagnetic converter 10 of the first embodiment, both
ends of the tape 12 bonded so as to divide the longitudinal direction of the surface of the thin
and flexible vibrating film 11 are supported by being sandwiched by the frame 30 By doing this,
partial large amplitudes of the divided vibration are suppressed, so that it is possible to prevent
the generation of abnormal noise and the disturbance of the sound pressure frequency
characteristics.
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[0019]
Although the non-woven tape is used as the tape 12 of the electromagnetic transducer 10 of the
first embodiment, the present invention is not limited to this, and a lightweight acetate tape, cloth
tape, which is not affected by the vibration of the vibrating membrane 11 You may use a paper
tape etc.
Moreover, it is preferable that the part which contacts the conductor coil 11b which becomes
high temperature at least at the time of electricity supply of these tapes 12 is a raw material with
high heat resistance.
[0020]
Further, in the tape 12 of the first embodiment, since the conductor coil 11b of the vibrating
membrane 11 has a high temperature, it is preferable to arrange the affixing position to the
vibrating membrane 11 so that the area contacting the conductor coil 11b is small. .
[0021]
Second Embodiment
FIG. 5 is a view showing the structure of the electromagnetic converter 10 according to the
second embodiment, and FIG. 5 (a) is a sectional view taken along the line A-A of FIG. It is a BB
sectional drawing of a). In the first embodiment, the vibrating film 11 is supported via both ends
of the tape 12 bonded so as to divide the longitudinal direction of the surface of the vibrating
film 11. However, in the second embodiment, the vibrating film 11 is The vibrating membrane
11 is supported via the extended portion 11 c which is extended. In addition, about the structure
similar to the electromagnetic transducer 10 of Embodiment 1, it shall be shown with the same
number also in the figure, and the description is abbreviate ¦ omitted.
[0022]
The vibrating membrane 11 is provided with an extended portion 11c extending in the short
direction at predetermined intervals, and the extended portion 11c is supported so as to be
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sandwiched by the frame 30 in the thickness direction.
[0023]
As described above, the electromagnetic converter 10 according to the second embodiment can
suppress the partial large amplitude due to the divided vibration by the above configuration, and
the same as the electromagnetic converter 10 according to the first embodiment. You can get the
effect.
[0024]
In the electromagnetic transducer 10 of the second embodiment, the vibrating film 11 is
supported by the frame via the extension 11c. However, the tape 12 of the electromagnetic
transducer 10 of the first embodiment is used in combination. May be supported.
[0025]
Third Embodiment
6 shows the structure of the electromagnetic converter 10 of the third embodiment, and FIG. 6
(a) is a sectional view taken along the line A-A of FIG. 1 (a), and FIG. 6 (b) is FIG. It is a BB
sectional drawing of a).
In the third embodiment, the vibrating membrane 11 is supported by the tape 12 (supporting
portion) of the first embodiment and the extension portion 11c (supporting portion) in which the
entire outer periphery of the vibrating membrane 11 of the second embodiment is extended.
Since the other configuration is the same as that of the first embodiment, it is denoted by the
same reference numeral in the figure and the description thereof is omitted.
[0026]
The vibrating membrane 11 has an extended portion 11c extending the entire outer peripheral
portion, and since the vibrating membrane 11 has substantially the same size as the surface of
the frame 30, the extended portion 11c is sandwiched by the frame 30 in the thickness direction.
It is supported.
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Further, the tape 12 is attached with an adhesive or the like so as to divide the longitudinal
direction of the surface of the vibrating film 11 at predetermined intervals, and both ends of the
tape 12 are supported so as to be sandwiched by the frame 30. .
[0027]
As described above, the electromagnetic converter 10 according to the third embodiment can
suppress the partial large amplitude due to the divided vibration by the above configuration, and
the same as the electromagnetic converter 10 according to the first embodiment. While being
able to acquire an effect, the large amplitude by the division vibration of the vibrating membrane
11 can be suppressed more.
[0028]
Although the electromagnetic transducer 10 of the third embodiment is the extension 11 c
provided on the entire outer periphery of the vibrating membrane 11, in consideration of the
driving of the vibrating membrane 11, of the two opposing pairs of rectangular sides One set
may be separated from the frame 30 by about 0.5 mm, and may be supported by the frame 30
via the extension 11 c on the other side and the tape 12.
[0029]
As described above, the electromagnetic transducer according to the present invention is
supported via the tape attached so as to divide the vibrating membrane, and the extending
portion formed by partially extending at least two opposing sides of the vibrating membrane.
Support, or because the tape and the extension are supported in combination, it is possible to
suppress partial large amplitude due to the divided vibration of the vibrating membrane, to
prevent the generation of abnormal noise, and to control the sound pressure frequency
characteristics. It can be made flat and stable.
[0030]
In the electromagnetic converter of the present invention, although the conductor coil 11b
having a meandering pattern is described as being formed on the surface of the vibrating film 11,
in order to convert the electric signal more faithfully as audio vibration, vibration is generated.
Conductor coils 11 b may be formed on both sides of the film 11.
[0031]
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Further, in the electromagnetic converter 10 of the present invention, the strip-like permanent
magnets 21 and 22 which are magnetized are used, but they may be magnetized after being fixed
to the frame 30, and they may differ in a strip at predetermined intervals. A permanent magnet
plate in which the magnetic poles are alternately magnetized may be used.
[0032]
Further, the arrangement of the conductor coil 11b and the permanent magnets 21 and 22
formed on the vibrating film 11 shown in the first to third embodiments of the present invention
is not limited to this combination, and for example, the length of the electromagnetic converter
10 The meandering shape may be formed as a longitudinal linear portion of the conductor coil
11b in the direction, and the longitudinal direction of the strip-like permanent magnets 21 and
22 may be arranged in the longitudinal direction of the electromagnetic converter 10.
[0033]
In the electromagnetic converter 10 according to the present invention, the circular sound
emission holes 31a and 32b are described, but the shape of the sound emission holes 31a and
32a is not limited to a circular shape. The shape and the size are designed according to the
purpose so that the vibration can be radiated efficiently.
[0034]
Moreover, each figure shown by embodiment of this invention is exaggerated and expanded and
shown for description, and relations, such as thickness of each structure, may differ from reality.
[0035]
It is the (a) perspective view and the (b) disassembled perspective view which show the external
appearance of the electromagnetic transducer 10 of this invention.
They are (a) AA line sectional view and (b) BB line sectional view of electromagnetic transducer
10 of a 1st embodiment.
FIG. 6 is a cross-sectional view along line AA showing an operation time of the electromagnetic
converter 10 of the first embodiment.
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FIG. 6 is a frequency-sound pressure level diagram showing sound pressure frequency
characteristics of the electromagnetic converter 10 of the first embodiment and the conventional
electromagnetic converter.
It is an (a) AA line sectional view showing the composition of electromagnetic transducer 10 of
Embodiment 2, and a (b) BB line sectional view.
It is an (a) AA line sectional view showing the composition of electromagnetic transducer 10 of
Embodiment 3, and (b) BB line sectional view.
It is the sectional view on the AA line showing the case of (a) 1/2 wavelength, (b) 1 wavelength,
and (c) 3/2 wavelength, when the division vibration state of the conventional electromagnetic
converter is (a) 1/2 wavelength.
Explanation of sign
[0036]
DESCRIPTION OF SYMBOLS 10 electromagnetic transducer, 11 vibrating membrane, 11a base
material, 11b conductor coil (coil), 11c extension part, 12 tapes, 21 upper permanent magnets,
22 lower permanent magnets, 30 frames, 31 upper frames (frames) 31a, 32a sound emission
hole, 32 lower frame (frame), 110 conventional electromagnetic transducer, 111 conventional
diaphragm.
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