JP2015029245

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DESCRIPTION JP2015029245
PROBLEM TO BE SOLVED: To provide an energy conversion device capable of obtaining
mechanical energy or electrical energy of sufficient size when adopting a configuration in which
a magnet substrate is disposed only on one side of a diaphragm. SOLUTION: An energy
conversion device is a device capable of mutually converting electrical energy and mechanical
energy, and includes a diaphragm 10 on which a coil having a wire pattern is formed, and a
magnet for generating a magnetic field to the coil A substrate 11 and a magnetic film 12 for
fixing the diaphragm 10 to the magnet substrate 11 by magnetic force are included. This device
may further include a nonmagnetic substrate 13 disposed between the magnet substrate 11 and
the diaphragm 10 and having flexibility to keep the distance between the magnet substrate 11
and the coil constant. [Selected figure] Figure 1
Energy conversion equipment
[0001]
The present invention relates to an energy conversion device for converting electrical energy into
mechanical energy or vice versa.
[0002]
As a device for converting electrical energy into mechanical energy or vice versa, an energy
conversion device having a structure in which a permanent magnet and a vibrating film are
combined is known, and is used as a flat speaker, headphones, a microphone or the like.
[0003]
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A device of this type usually comprises a permanent magnet plate, a vibrating membrane
arranged to face the permanent magnet plate, a buffer member interposed between the
permanent magnet plate and the vibrating membrane, and a permanent magnet plate. And a
support member that regulates the relative position of the vibrating film (see, for example, Patent
Documents 1 to 3).
In the above device, the permanent magnet plates are not limited to the both sides of the
vibrating film, but may be disposed on only one side.
[0004]
In order to cause the vibrating membrane to vibrate properly, the movement of the vibrating
membrane must be prescribed to a certain degree, that is, the vibrating membrane should be
fixed so as not to be displaced more than a certain amount in the in-plane direction.
Here, the in-plane direction is a two-dimensional direction parallel to the surface of the vibrating
membrane. However, in the above-mentioned configuration arranged only on one side, such a
fixing method is difficult and can not be easily fixed.
[0005]
For this reason, in the case of adopting the above-described configuration arranged on only one
side, it is difficult to vibrate the vibrating film properly, and it has been difficult to obtain
sufficient mechanical energy or electrical energy.
[0006]
The present invention has been made in view of the above problems, and is an energy conversion
device capable of performing mutual conversion between electrical energy and mechanical
energy, which is a diaphragm in which a coil having a conductor pattern is formed, and a coil An
energy conversion device is provided that includes a magnet substrate generating a magnetic
field to the magnetic substrate and a magnetic film fixing the diaphragm to the magnet substrate
by magnetic force.
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[0007]
According to the present invention, the diaphragm can be easily fixed, and mechanical energy or
electrical energy of sufficient size can be obtained.
[0008]
The side view which showed one structural example of the energy conversion apparatus.
FIG. 2 is a plan view of the energy conversion device shown in FIG. 1.
The side view which showed the other structural example of the energy conversion apparatus.
The figure which showed the 1st test condition with the table. FIG. 8 is a table showing the
results for the first test condition. The figure which showed the 2nd test condition with the table.
A table showing the results for the second test condition.
[0009]
The energy conversion device of the present invention is a device capable of mutually converting
electrical energy into mechanical energy and mechanical energy into electrical energy, and is a
device which can be used for the above-mentioned flat speaker, headphone, microphone or the
like.
[0010]
FIG. 1 is a diagram showing one configuration example of the energy conversion device.
This energy conversion device is configured to include at least the diaphragm 10, the magnet
substrate 11, and the magnetic film 12. In addition to these, in FIG. 1, the nonmagnetic substrate
13 is comprised. The magnet substrate 11 generates a magnetic force that attracts the
ferromagnetic material 14, and the magnetic substrate 11 is attached to the ferromagnetic
material 14 by the magnetic force.
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[0011]
The ferromagnetic substance 14 is a substance which is strongly magnetized when placed in a
magnetic field and remains magnetic even when removed from the magnetic field, and iron,
cobalt, nickel, alloys thereof, ferrite, samarium iron or the like can be used. The shape and size of
the ferromagnetic body 14 may be any shape and size as long as the magnet substrate 11 can be
attached.
[0012]
The magnet substrate 11 generates a magnetic force that attracts with the ferromagnetic body
14, adheres to the ferromagnetic body 14, and also generates a magnetic force that attracts with
the magnetic film 12 made of a magnetic body. The magnetic film 12 is drawn. This eliminates
the need for an adhesive for sticking.
[0013]
One surface of the magnet substrate 11 is adjacent to the ferromagnetic body 14 in a sticking
manner, and the other surface on the opposite side is disposed adjacent to one surface of the
nonmagnetic substrate 13. One surface of the diaphragm 10 is adjacent to the other surface of
the nonmagnetic substrate 13, and the magnetic film 12 is disposed adjacent to the other surface
of the diaphragm 10. The above-described magnetic force is generated between the magnet
substrate 11 and the magnetic film 12 and the magnetic film 12 is attracted, so the nonmagnetic
substrate 13 and the diaphragm 10 in between are the magnet substrate 11 and the magnetic
film 12. It is held by The diaphragm 10 is held so as to be capable of vibrating by its magnetic
force.
[0014]
In the past, a housing was provided and fixed to the housing so as to prevent the diaphragm 10
from fluttering, but by adopting such a configuration to hold in this way, the housing can be
easily fixed without providing the housing. can do. Moreover, since it is not necessary to provide
a housing ¦ casing, it becomes possible to provide at low cost.
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[0015]
In the related art, in order to support the diaphragm 10 and the like on the magnet substrate 11,
a hole is provided in the magnet substrate 11 and the hole is fixed to the hole through the
support member. The cost can be reduced.
[0016]
The magnet substrate 11 may be, for example, a square flat plate, and a parallel stripe magnetic
pattern in which strip-like N and S poles alternately appear over the entire surface.
Such a magnetized pattern can be created by laminating and integrating unsintered magnet
sheets and sintering. The magnet substrate 11 is not limited to a square flat plate, and may be
circular, oval, rectangular or the like.
[0017]
In the magnet substrate 11 having such a magnetized pattern, the magnetic field component
perpendicular to the surface is largest near the center of the magnet surface of each pole and
smallest near the boundary between the N pole and the S pole. Actually, the magnetic lines of
force pass in an arc shape from the N pole to the S pole, and the magnetic field component
contributing to the vibration of the diaphragm 10 becomes a component in the horizontal
direction with respect to the magnet surface. The component in the horizontal direction most
effectively acts near the boundary between the N pole and the S pole.
[0018]
For this reason, a linear portion of a coil made of a conducting wire pattern is provided at the
position of the diaphragm 10 corresponding to the vicinity of the boundary, and alternating
current is supplied to the coil. It can be vibrated efficiently. At this time, the magnet substrate 11
generates a magnetic field in the direction perpendicular to the direction in which the coil
extends.
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[0019]
It is desirable that the conductor pattern and the magnetization pattern that make up the coil be
the same pattern, that is, the spacing between the N pole and the S pole of the magnetization
(pitch of the magnetization pattern) be the same as the pitch of the coil. In addition, even if it is
not completely the same, it may be an approximate pattern. By making the pattern approximate
in this manner, the magnetic field (leakage magnetic field) generated around the magnet
substrate 11 can be effectively transmitted to the coil.
[0020]
As a magnet, although a ferrite magnet, a neodymium magnet, an alnico magnet, a samarium
cobalt magnet etc. can be mentioned, in order to enlarge sound pressure, the neodymium magnet
with strong magnetic force is preferable. However, other magnets can be adopted according to
the purpose.
[0021]
Since it is not necessary to provide a hole in the magnet substrate 11 as described above, the
energy conversion device is useful when used as a device that outputs sound only in one
direction (one side) like a flat speaker.
[0022]
The diaphragm 10 can use the thing in which the coil which consists of conducting wire patterns
was formed in the position corresponding to the boundary vicinity of the said N pole and S pole.
The diaphragm 10 may be made of a flexible resin substrate such as polyethylene terephthalate
(PET), polyimide, or polyethylene naphthalate (PEN) having a thickness of about 10 to 30 μm,
and the above coil is formed in close contact with the substrate. .
[0023]
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The resin substrate does not require transparency, but some rigidity is required to vibrate. For
example, a diaphragm in which a coil of 9 μm in thickness is formed in close contact with a
polyimide substrate of 25 μm in thickness can be used. By the way, the flexural modulus of
polyimide is 3100 MPa, and PET and PEN are almost equal and about 2200 MPa. As the
vibration area is larger, the amplitude is larger, so that larger mechanical energy can be obtained.
[0024]
The coil can be formed, for example, by closely etching a polyimide substrate with copper foil by
wet etching. It is not limited to this, It is also possible to form using printing methods, such as
screen printing, using a copper paste. Screen printing is desirable in that it can be formed with
uniform thickness and pitch. The width or length of the coil is not an arbitrary width or length,
but a width or length defined by impedance. Moreover, in order to connect a coil to a power
supply, the positive terminal and the negative terminal are provided in the both ends.
[0025]
The nonmagnetic substrate 13 is provided to prevent collision with the magnet substrate 11 to
generate abnormal noise when the diaphragm 10 vibrates, and to prevent generation of divided
vibration of the diaphragm 10 itself. When the energy conversion device is used as a speaker, by
interposing the nonmagnetic substrate 13 between the magnet substrate 11 and the diaphragm
10, it is possible to suppress the generation of sound waves other than the sound wave that is
faithful to the sound source.
[0026]
The nonmagnetic substrate 13 may be any substrate having a constant thickness and flexibility
to keep the distance between the magnet substrate 11 and the coil constant, and made of a
nonmagnetic material that does not stick to the magnet. It may be. Examples of the nonmagnetic
substrate 13 include paper, Japanese paper, and cellulose fibers such as clean wipes. Since it is a
nonmagnetic material, it may be a nonmagnetic metal material such as aluminum, but since a
certain degree of flexibility is required, a nonmetallic material such as the above-mentioned
paper is preferable.
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[0027]
The thickness of the nonmagnetic substrate 13 is, for example, in the range of about several μm
to 0.5 mm, and in consideration of the leakage magnetic field, a paper of about several tens of
μm to several hundreds of μm or clean paper usable in a clean room is preferable. When using
an energy conversion device as a speaker, clean paper is desirable because dust or the like does
not come out even if there is no case covering the entire speaker. The nonmagnetic substrate 13
may be equal to or less than the size of the magnet substrate 11 depending on the thickness, or
may be a partial linear array.
[0028]
The magnetic film 12 can be formed on a flexible transparent substrate (transparent substrate)
or can be formed directly on the diaphragm 10. Examples of the material that can be used as the
magnetic film 12 include metal magnetic materials including iron, cobalt, ferrite, samarium iron
and the like. In addition, iron oxide may contain cobalt, nickel, manganese, a resin or the like. As
resin, a phenol resin, an epoxy resin, a urethane resin, a silicone resin etc. can be mentioned. The
magnetic film 12 may be any other material as long as it is a material having magnetism to be
attached to a magnet.
[0029]
The magnetic film 12 can be formed on a transparent substrate using a printing method such as
screen printing. Although it is not common to form the magnetic film 12 by the printing method,
for example, it may be formed using a mixture of a magnetic material consisting of ferrite and
samarium iron and a screen printing ink at a ratio of 6: 4. it can. Specifically, the magnetic
substance is used after being crushed and pasted with a rocking mill. The above mixture is
formed by screen printing on PET having a thickness of 100 μm with a width matched to the
pitch of the magnetized pattern of the magnet substrate 11 and the pitch of the conductive
pattern. Thereafter, it is cured by heating at a temperature of 120 ° C. for about 30 minutes.
This is an example and is not limited to this ratio, temperature and time.
[0030]
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As the transparent substrate, in addition to the above-mentioned PET, a film formed from a
polyester such as polypropylene, polyethylene, polyamide, PEN or the like, which has been cut
into an appropriate size, can be used.
[0031]
As the transparent substrate, a film or the like cut into an appropriate size may be used as it is, or
a hole may be provided by hollowing out at least a part other than the portion on which the
magnetic film 12 is formed.
When the energy conversion device is used as a speaker, if the entire surface is covered with a
transparent substrate, the sound is absorbed, and thus the holes can reduce or eliminate the
sound absorption.
[0032]
Note that the magnetic film 12 may be formed on each of a plurality of small transparent
substrates cut out and not limited to the formation of holes, and may be disposed adjacent to an
arbitrary part so as to cover at least a part of the diaphragm 10 . By doing this, a gap can be
formed between the transparent substrates, and sound can be output from the gap.
[0033]
In the case of direct formation on the diaphragm 10, after the coil is formed, the surface is
subjected to ultrasonic cleaning with ethanol, and thereafter, it is formed by the printing method
such as screen printing as in the case of forming on the above transparent substrate. Can.
[0034]
FIG. 2 is a plan view of the energy conversion device shown in FIG.
The coil 15 and the magnetic film 12 will be described in detail with reference to this plan view.
The energy conversion device is formed by using the magnet substrate 11, the transparent
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substrate on which the magnetic film 12 is formed, the nonmagnetic substrate 13, and the
diaphragm 10 on which the coil 15 is formed in close contact. Although all can be made the
same size except for the diaphragm 10, in order to make the structure intelligible in FIG.
[0035]
A rectangular nonmagnetic substrate 13 is disposed on a rectangular magnet substrate 11, a
rectangular diaphragm 10 is disposed thereon, and a rectangular transparent substrate on which
a magnetic film 12 is formed is disposed as a magnetic substrate 16 Magnetic force is generated
between the magnet substrate 11 and the magnetic film 12. The nonmagnetic substrate 13 and
the diaphragm 10 between the magnet substrate 11 and the magnetic film 12 are held between
the magnet substrate 11 and the magnetic film 12 by the magnetic force.
[0036]
As shown in FIG. 2, the coil 15 is provided with two terminals (not shown) for connecting to a
power supply on the lower side, and can be a conductor pattern formed in a meander or pulse
shape. By forming it as a conducting wire pattern of such a shape, it is possible to provide coil
portions extending in one direction in the vicinity of the boundaries of the N pole and the S pole
of the magnetized pattern formed on the magnet substrate 11 respectively.
[0037]
The magnetic film 12 is provided so as to be located between the coils extended in one of the
conductor patterns formed on the diaphragm 10. Further, the magnetic film 12 only needs to be
able to sandwich the nonmagnetic substrate 13 and the diaphragm 10, so as shown in FIG. 2, it
can be provided only on the left and right sides toward the transparent substrate.
[0038]
In FIG. 2, the magnetic films 12 are provided in two lines on each of the left and right sides.
However, the present invention is not limited to this. One line may be provided on each of the left
and right sides. It is also good.
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[0039]
In this energy conversion device, when an alternating current is caused to flow through the coil
15, a force acts in the thickness direction of the diaphragm 10 to vibrate the diaphragm 10 in the
thickness direction.
This vibration can convert electrical energy into mechanical energy. The mechanical energy
vibrates the air as described above and can be output as a sound wave. The energy conversion
device can also convert mechanical energy into electrical energy by vibrating the diaphragm 10
from sound waves and generating alternating current with the coil 15 according to the law of
Fleming's right hand by the vibration. The former conversion allows the energy conversion
device to be used as a headphone or a speaker, and the latter conversion allows the energy
conversion device to be used as a microphone.
[0040]
The magnetic film 12 may be magnetized, but the leakage magnetic field from the magnetic film
12 is smaller than the minimum leakage magnetic field of the magnet substrate 11 in order to
generate a magnetic force that attracts the magnetic substrate 11. It is assumed.
[0041]
The magnet substrate 11 can be magnetized so that the leakage magnetic field to the side where
the diaphragm 10 is disposed and the leakage magnetic field to the side of the ferromagnetic
body 14 that is the back side have the same strength.
Further, magnetization can be performed such that the leakage magnetic field to the side where
the diaphragm 10 is disposed is stronger than the leakage magnetic field to the rear side.
[0042]
Magnetization refers to magnetizing a magnetic body, and magnetization can be performed, for
example, by applying an external magnetic field using an electromagnet. By performing this
magnetization only on one side of the magnetic body, the non-magnetized side is also
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magnetized, but the magnetized side can be magnetized strongly.
[0043]
When the magnetization is performed so that the leakage magnetic fields on both sides of the
magnet substrate 11 have the same strength, the both sides become strong leakage magnetic
fields, and therefore, when attached to the ferromagnetic body 14, it becomes difficult to remove.
On the other hand, when only one side is magnetized as described above, the leakage magnetic
field from the back side is relatively weak, so that it can be easily applied and also easy to
remove. This facilitates handling.
[0044]
In the embodiment shown in FIG. 1 and FIG. 2, both the diaphragm 10 and the magnet substrate
11 are flat-shaped, so when used as a speaker, although high-pitched sound is emitted, no lowpitched sound is emitted or It has the drawback of being difficult. The bass requires a large
vibration, but the flat type has a short distance between the nonmagnetic substrate 13 and the
coil, so that it is difficult to obtain a large vibration.
[0045]
Therefore, as shown in FIG. 3, the shape of the diaphragm 10 can be made to have a corrugated
cross-sectional shape. The coil 15 is formed in close contact with the top of the wave-shaped
diaphragm 10 most distant from the nonmagnetic substrate 13, and the magnetic film 12 having
a substantially U-shaped cross section is disposed in each groove closest to the nonmagnetic
substrate 13. it can. As described above, by providing a gap between the nonmagnetic substrate
13 and the coil 15 and lengthening the distance, it is possible to obtain a large vibration. A
magnetic force that attracts each other may be generated between the magnetic film 12 and the
magnet substrate 11 to hold the diaphragm 10 and the nonmagnetic substrate 13 therebetween.
[0046]
The diaphragm 10 is preferably formed as follows. The pitch of the conductor pattern of the coil
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15 is formed wider than the pitch of the magnetized pattern in which the N pole and the S pole of
the magnet substrate 11 appear alternately. The conductor pattern and the magnetizing pattern
have the same degree of pitch, and the cross-sectional shape is formed into a corrugated shape
by molding in a mold and pressing.
[0047]
By making the pitch of the conductor pattern equal to the pitch of the magnetic pattern and
arranging so that the boundary between the N pole and the S pole is located at the center
between the portions extended in one of the conductive patterns, the leakage magnetic field is
increased, A low sound of sufficient sound pressure can be output.
[0048]
The magnetic film 12 can be formed in each groove on the transparent substrate whose crosssectional shape is a corrugated shape so that the cross-sectional shape can be disposed adjacent
to the diaphragm 10 having a corrugated shape. It can also be formed directly on top.
[0049]
In the case of direct formation on the vibrating plate 10, after the coil is formed in close contact,
the surface may be ultrasonically cleaned with ethanol, and then the magnetic film 12 may be
formed by screen printing.
Since the magnetic film 12 covers the entire surface of the diaphragm 10 and the output sound is
stagnant, the magnetic film 12 is formed in one row or two rows at both ends of the diaphragm
10 or in three rows at both ends and the center can do.
These are merely examples, and three rows may be formed at both ends.
[0050]
Various tests were conducted using the energy conversion device as a speaker. FIG. 4 is a table
showing the test conditions. The loudspeaker is a flat loudspeaker and is of the structure and
configuration as shown in FIGS. 1 and 2. The flat speaker is composed of a magnetic substrate 16
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provided with a rectangular magnet substrate 11, a nonmagnetic substrate 13, a diaphragm 10,
and a magnetic film 12.
[0051]
In all of Examples 1 to 7 and Comparative Example 1, the leakage magnetic field toward the
ferromagnetic body 14 was ± 24 mT, the leakage magnetic field toward the diaphragm 10 was
± 95 mT, and the diaphragm 10 was formed to be strong. . In Example 8 only, the leakage
magnetic fields on both sides were formed to be the same ± 95 mT. For Examples 2, 4 and 6, the
thickness of the nonmagnetic substrate 13 was 0.2 mm, twice that of the other Examples and
Comparative Example 1. In Examples 3 and 4, the thickness of the coil 15 is about 5 μm thicker
than in the other Examples and Comparative Examples to 35 μm, and in Examples 5 and 6 is
about 10 μm thick and 40 μm. In Examples 7 and 8, the pitch of the coil 15 was set to 6 mm,
which is twice that of the other Examples and Comparative Example 1.
[0052]
In Examples 1, 3, 5, 7 and 8, the material of the magnetic film 12 is ferrite, and the size thereof is
15 mm × 115 mm, and the number is two. In Examples 2, 4 and 6, the material of the magnetic
film 12 is SmFe (samarium iron), the size thereof is 20 mm × 115 mm, and the number thereof
is three. The magnetic film 12 was formed by the above-described printing method on Lumira
(registered trademark) having a thickness of 100 μm manufactured by Toray Industries, Inc.
Ferrite is OP-56 made by Dowa F-Tech Co., Ltd., SmFe is J16 made by Nichia Chemical Industries,
Ltd. Ink for screen printing is a low temperature curing adhesive RCA (registered trademark)
made by Solar Ink Mfg. Co., Ltd.-2000 Was used. Curing of the magnetic film 12 was performed
by heating at 120 ° C. for 30 minutes.
[0053]
The test results are shown in FIG. In each of the first to eighth embodiments, since the magnetic
film 12 is provided, the diaphragm 10 can be held in the speaker, and a good sound pressure can
be obtained at an absolute sound pressure of 1 to 5 kHz. It was also possible to attach to the
ferromagnetic body 14. In Example 8, the leakage magnetic fields on both sides were made the
same, and since it was as strong as ± 95 mT, it could not be removed easily. In Comparative
Example 1, since the magnetic film 12 was not present, the diaphragm 10 could not be fixed, and
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no sound could be output.
[0054]
From this result, the nonmagnetic substrate 13 and the vibration plate 10 are sandwiched
between the magnetic substrate 11 and the magnetic film 12 and the structure and configuration
are only sandwiched by the magnetic force generated between them, but good acoustic
characteristics are obtained. It could be found that was obtained. In addition, it has been found
that the diaphragm 10 can be easily fixed simply by sandwiching the diaphragm 10, and it can be
easily removed by weakening the leakage magnetic field on the ferromagnetic body 14 side.
[0055]
Comparing Examples 1 to 6 with Example 7, the absolute sound pressure is larger and the
acoustic characteristics are higher in Examples 1 to 6 in which the pitch of the conductor pattern
and the pitch of the magnetized pattern are the same 3 mm. It could be found that it was good. In
addition, it has been found that the absolute sound pressure is not greatly influenced by the
thickness of the nonmagnetic substrate, the thickness of the coil, the material and the number of
the magnetic film 12, the size and the like.
[0056]
From the above, it is possible to easily fix the diaphragm 10 by sandwiching the diaphragm 10
between the magnetic film 12 and the magnet substrate 11 and sandwiching the diaphragm 10
with magnetic force generated therebetween, and good acoustic characteristics You can get It is
preferable to form a leakage magnetic field to the diaphragm 10 side of the magnet substrate 11
stronger than the leakage magnetic field to the ferromagnetic body 14 side of the back side in
terms of easy removal. Further, it is preferable to make the pitch of the conductor pattern
approximately the same as the pitch of the magnetized pattern in that the sound pressure can be
further increased.
[0057]
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Next, test conditions of a test performed using a flat speaker having the structure and
configuration as shown in FIG. 3 are shown in FIG. The flat speaker is composed of a rectangular
magnetic substrate, a nonmagnetic substrate, a diaphragm, and a transparent substrate provided
with a magnetic film.
[0058]
In each of the first to sixth embodiments, a diaphragm having a corrugated cross-sectional shape
is used as the diaphragm 10, and in the first to third comparative examples, a planar diaphragm
is used. Incidentally, Comparative Examples 2 and 3 were carried out using the flat speaker of
the configuration shown in FIG. 1 in order to compare the difference due to the shape of the
diaphragm. In each of Examples 1 to 6 and Comparative Examples 1 and 2, the leakage magnetic
field toward the ferromagnetic body 14 is ± 24 mT, the leakage magnetic field toward the
diaphragm 10 is ± 95 mT, and the diaphragm 10 is strongly formed. Only in Comparative
Example 3, the leakage magnetic fields on both sides were formed to have the same ± 95 mT.
For Examples 2, 4 and 6, the thickness of the nonmagnetic substrate 13 was 0.2 mm, twice that
of the other Examples and Comparative Example 1. In Examples 3 and 4, the thickness of the coil
15 is about 5 μm thicker than in the other Examples and Comparative Examples to 35 μm, and
in Examples 5 and 6 is about 10 μm thick and 40 μm.
[0059]
In Examples 1 to 6 and Comparative Example 2, the pitch of the coil 15 is formed to 6 mm, which
is twice the pitch of the magnetized pattern, and for Example 1 to 6, the pitch of the coil 15 is
magnetized by making it a waveform. It was 3 mm the same as the pitch of the pattern.
[0060]
In Examples 1, 3 and 5 and Comparative Examples 2 and 3, the material of the magnetic film 12
is ferrite, and the size thereof is 15 mm × 115 mm, and the number is two.
In Examples 2, 4 and 6, the material of the magnetic film 12 is SmFe (samarium iron), the size
thereof is 20 mm × 115 mm, and the number thereof is three. The magnetic film 12 was formed
by the above-described printing method on Lumira (registered trademark) having a thickness of
100 μm manufactured by Toray Industries, Inc. Ferrite is OP-56 made by Dowa F-Tech Co., Ltd.,
SmFe is J16 made by Nichia Chemical Industries, Ltd. Ink for screen printing is a low
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temperature curing adhesive RCA (registered trademark) made by Solar Ink Mfg. Co., Ltd.-2000
Was used. Curing of the magnetic film 12 was performed by heating at 120 ° C. for 30 minutes.
[0061]
The test results are shown in FIG. In each of Examples 1 to 6 and Comparative Examples 2 and 3,
since the magnetic film 12 is provided, the diaphragm 10 can be held in the speaker, and good
sound pressure can be obtained at an absolute sound pressure of 1 to 5 kHz. The It was also
possible to attach to the ferromagnetic body 14.
[0062]
In Comparative Example 3, since the leakage magnetic fields on both sides were made the same
and ± 95 mT intensified, they could not be easily removed. Although the comparative example 3
obtained sufficient sound pressure larger than Examples 1-6 regarding a high-pitch range, only
about half the sound pressure was obtained with respect to a low-pitch range. Comparative
Example 2 also obtained sufficient sound pressure larger than that of Examples 1 to 6 with
respect to the high range, but only about half the sound pressure with respect to the low range.
[0063]
In Comparative Example 1, since there was no magnetic film 12, the diaphragm 10 could not be
fixed, and no sound could be output.
[0064]
From this result, the nonmagnetic substrate 13 and the vibration plate 10 are sandwiched
between the magnetic substrate 11 and the magnetic film 12 and the structure and configuration
are only sandwiched by the magnetic force generated between them, but good acoustic
characteristics are obtained. It could be found that was obtained.
In addition to that, it could be found out that better acoustic characteristics can be obtained by
forming the diaphragm 10 so that the cross-sectional shape becomes a corrugated shape.
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[0065]
Further, the sound output from the speaker was measured using a measurement microphone
(Type 4152) manufactured by Accor Corporation. The sound source used the music CD and
adopted the peak value of the same time zone. As a result, it was confirmed that the sound in the
low-pitch range from 700 Hz to 3 kHz was particularly large compared to a flat one by using the
diaphragm 10 whose cross-sectional shape is a waveform shape.
[0066]
From this, although the diaphragm 10 may be a simple flat plate whose cross-sectional shape is
flat, it is preferable that the cross-sectional shape is a corrugated shape. Further, it is preferable
to form a leakage magnetic field to the diaphragm 10 side of the magnet substrate 11 stronger
than the leakage magnetic field to the ferromagnetic body 14 side on the back side, in terms of
easy removal. Furthermore, it is preferable to make the pitch of the conductor pattern equal to
the pitch of the magnetized pattern in that the sound pressure can be further increased.
[0067]
In the closed or cone type speaker design, the resonance frequency that determines the sound
quality can be determined from a simple impedance or inductance. Conventionally, in the design
of a speaker (one-sided free speaker) employing a configuration in which the magnet substrate
11 is disposed only on one side of the diaphragm 10, the resonant frequency is determined from
a simple impedance etc. I could not do that. However, since the magnetic film 12 can be easily
fixed while restricting the displacement in the in-plane direction, the resonance frequency can be
determined from the impedance or the like. Therefore, even with a single-sided free speaker,
good acoustic characteristics can be obtained.
[0068]
Although the present invention has been described above using the embodiment described above
as the energy conversion device, the present invention is not limited to the above-described
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embodiment. The present invention can be modified within the scope of those skilled in the art,
such as other embodiments, additions, modifications, deletions, etc., as long as the functions and
effects of the present invention can be exhibited in any aspect. It is included in the scope of the
invention.
[0069]
Therefore, the present invention can also be provided as a flat speaker, headphone, microphone
or the like using the energy conversion device.
[0070]
DESCRIPTION OF SYMBOLS 10 ... Diaphragm, 11 ... Magnet board ¦ substrate, 12 ... Magnetic
film, 13 ... Nonmagnetic board ¦ substrate, 14 ... Ferromagnetic body, 15 ... Coil, 16 ... Magnetic
board
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JP-A-9-331596 JP-A-2010-251816 JP-A-2010-268045
10-05-2019
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