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JP2003339100

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Notice
This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate,
complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or
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DESCRIPTION JP2003339100
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
loudspeaker suitable as a thin flat-plate loudspeaker and a loudspeaker system using the
loudspeaker.
[0002]
2. Description of the Related Art It is expected that thin flat loudspeakers can be used in various
applications because they do not occupy a large installation space. As a thin flat-plate speaker of
this type, when the diaphragm is relatively large, a method of driving the diaphragm with a
plurality of voice coils has been adopted in order to suppress divided vibration.
[0003]
For example, as shown in FIG. 11, the diaphragm 200 made of, for example, a rectangular flat
plate and to which the peripheral portion 200a is fixed is driven pointwise at the center position
201 of the diaphragm 200 as shown in FIG. Considering the case, the diaphragm 200 vibrates as
shown in the cross-sectional view of FIG.
[0004]
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1
That is, as shown in FIG. 12A, when the center position 201 of the diaphragm 200 receives an
upper driving force, the diaphragm 200 is convex upward as shown in FIG. 12B. Transform into a
shape that
At this time, the portion 202 shifted from the central position 201 of the diaphragm 200 does
not move immediately because of the mass of the diaphragm itself, and moves upward so as to
be later than the upward displacement of the central position. do.
[0005]
Thereafter, when the center position 201 of the diaphragm 200 receives a driving force
downward, the center position 201 of the diaphragm 200 is immediately displaced downward as
shown in FIG. 12C by the driving force, but the center position At this time, since the portion 202
deviated from 201 still has an upward inertia, it tries to keep moving upward as shown in FIG.
12C. Therefore, the diaphragm 200 is divided and vibrated as a whole as shown in FIG.
[0006]
Therefore, conventionally, a flat plate speaker using a plurality of voice coils has been proposed
to simultaneously drive the diaphragm 200 at not only the central position 201 but also the
portion 202 and other portions.
[0007]
However, in the case of such a flat plate speaker using a plurality of voice coils, there is a
problem that the structure becomes complicated and the price becomes high.
[0008]
An object of the present invention is to provide a speaker capable of solving this problem.
[0009]
SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a loudspeaker
according to the invention of claim 1 has a plate-like permanent magnet which has a
predetermined thickness and is magnetized in the thickness direction; A coil winding portion in
which current flows in a direction intersecting with the magnetic flux from the permanent
magnet comprises a voice coil disposed so as to be located in a space for the thickness of the
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2
permanent magnet, and a conductive material The vibration plane in the direction orthogonal to
the thickness direction of the permanent magnet is spaced apart from one side in the thickness
direction of the permanent magnet by an amount corresponding to the vibration amplitude of the
vibration plane. A diaphragm disposed, the diaphragm being driven by an interaction force
generated between an eddy current generated in the diaphragm when a voice current flows
through the voice coil and a magnetic flux from the permanent magnet It is characterized by
making it vibrate.
[0010]
According to the speaker of the invention of claim 1 of the above-mentioned configuration, the
diaphragm is generated by the force due to the interaction generated between the eddy current
generated in the diaphragm by the voice current flowing through the voice coil and the magnetic
flux from the permanent magnet. Vibrates.
In this case, since the magnetic field generated by the permanent magnet is generated in a
relatively wide range, and the eddy current is generated in a relatively wide range in the
diaphragm, the diaphragm is characterized in that divided vibration hardly occurs.
And there is an advantage that the configuration is simple, and therefore, it can be manufactured
inexpensively.
[0011]
In the speaker according to the second aspect of the present invention, the plate-like permanent
magnet magnetized in the thickness direction has a predetermined thickness, and a current flows
in a direction intersecting the magnetic flux from the permanent magnet. The coil winding
portion is made of a conductive material and a voice coil disposed so as to be located in a space
corresponding to the thickness of the permanent magnet, in a direction orthogonal to the
thickness direction of the permanent magnet The first vibrating plate is arranged such that the
vibrating surface is at a position separated from one side in the thickness direction of the
permanent magnet by an amount corresponding to the vibration amplitude of the vibrating
surface, and is made of a conductive material. The vibration plane in the direction orthogonal to
the thickness direction of the permanent magnet is separated from the other side in the thickness
direction of the permanent magnet by an amount corresponding to the vibration amplitude of the
vibration plane. A second diaphragm disposed, and centers of the first diaphragm and the second
diaphragm A portion facing the position and the vicinity thereof is a space, and in this space
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portion, a connecting member for connecting the first diaphragm and the second diaphragm is
provided, and voice electricity flows in the voice coil The first diaphragm and the second
diaphragm are vibrated by the interaction generated between the eddy current generated in the
first diaphragm and the second diaphragm and the magnetic flux from the permanent magnet. It
is characterized by
[0012]
In the speaker according to the second aspect of the present invention, the first diaphragm is
provided on one side in the thickness direction of the permanent magnet magnetized in the
thickness direction, and on the other side in the thickness direction of the permanent magnet ,
And a second diaphragm.
[0013]
When an audio signal current is supplied to the voice coil, eddy currents are induced in the first
and second diaphragms, and the eddy currents and the magnetic flux from the permanent
magnet make the direction orthogonal to the first and second diaphragms. The first and second
diaphragms vibrate.
[0014]
At this time, when the first diaphragm vibrates in the direction approaching the permanent
magnet, the second diaphragm vibrates in the direction away from the permanent magnet, and
the first diaphragm moves away from the permanent magnet. When it vibrates, the lines of
magnetic force from the permanent magnet become weak.
That is, when one of the diaphragms moves away from the permanent magnet and the magnetic
flux becomes weak, the other diaphragm approaches the permanent magnet and the magnetic
flux becomes stronger.
Also, when one of the diaphragms approaches the permanent magnet and the magnetic lines of
force become stronger, the other diaphragm moves away from the permanent magnet and the
magnetic lines of force become weaker.
[0015]
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4
When there is only one diaphragm, when the vibrating surface of the diaphragm vibrates in the
direction approaching the permanent magnet, the magnetic lines of force from the permanent
magnet become larger, while when vibrating in the direction away from the permanent magnet,
the diaphragm from the permanent magnet As the lines of magnetic force become weak, in
accordance with the vibration of the diaphragm, strong and weak lines occur in the lines of
magnetic force where the eddy currents interlink, so even-order distortion occurs in the vibration
of the diaphragm and the acoustic quality is degraded. Although there is a problem, in the
invention of claim 2, as described above, since the two diaphragms move in a complementary
manner, even-order vibration distortion can be eliminated.
[0016]
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] A first
embodiment of a loudspeaker according to the present invention will be described with reference
to FIGS.
FIG. 1 is an exploded perspective view of the thin flat plate speaker according to this
embodiment, FIG. 2 is a cross sectional view thereof, and FIGS. 3 and 4 are diagrams for
explaining the vibration principle.
[0017]
The thin flat loudspeaker has a structure in which the diaphragm 2, the voice coil 3 and the
permanent magnet 4 are attached to the frame 1.
[0018]
The frame 1 is made of a nonmagnetic and nonconductive material, for example, a rectangular
plate of wood.
In this example, the frame 1 has a square outer shape.
A through hole 11 for disposing the voice coil 3 and the permanent magnet 4 is bored in the
center of the frame.
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The through hole 11 has a predetermined radius centered on the center position of the frame 1.
[0019]
The plurality of through holes 12 formed around the through holes 11 of the frame 1 is for
reducing the overall weight of the frame 1 to such an extent that the strength of the frame 1 is
not impaired.
[0020]
A plurality of screw holes 13 for attaching the diaphragm 2 to the frame 1 are provided on the
side surface (thickness portion) of the frame 1.
Further, around the through hole 11 of the frame 1, a plurality of screw holes 14 for fixing a
voice coil bobbin 5 described later to the frame 1 are provided at equal intervals in this example,
four in this example. .
[0021]
The voice coil 3 is wound in a ring around a voice coil bobbin 5 made of nonmagnetic and
nonconductive materials.
In this case, the direction of the winding axis of the voice coil bobbin 5 is parallel to the thickness
direction of the frame 1. Flanges 51 and 52 are formed at both ends of the bobbin 5 in the
winding axis direction.
[0022]
In the case of this example, one flange portion 51 of the voice coil bobbin 5 has a plurality of
projecting portions 54 provided with screw holes 53 for fixing the bobbin 5 in the frame 1 at
equal intervals in this example. , Four are formed. The protruding portion 54 is formed to
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protrude outward in the radial direction of the flange portion 51.
[0023]
Then, as shown in FIG. 2, in the voice coil bobbin 5 around which the voice coil 3 is wound, the
screw 55 is in the flange portion 51 such that the portion of the voice coil 3 is positioned in the
through hole 11 of the frame 1. It is fixed to the frame 1 by being screwed into the screw holes
14 of the frame 11 through the screw holes of the projection 54 of the
[0024]
The permanent magnet 4 has a disk shape and is magnetized in the thickness direction.
In this example, the radius of the permanent magnet 4 is selected to be substantially equal to the
radius of the hollow portion 56 of the voice coil bobbin 5. Then, the permanent magnet 4 is
housed in the hollow portion 56 of the voice coil bobbin 5 as shown in FIG.
[0025]
In this case, the flange portion 52 of the voice coil bobbin 5 which is not attached to the frame 1
has a projecting portion 52a which protrudes in the radial direction toward the hollow portion
56 side, and the hollow portion 56a The peripheral portion of the permanent magnet 4 housed
inside is supported.
[0026]
On the other hand, a stepped portion 57 is provided in the flange portion 51 of the voice coil
bobbin 5 to be attached to the frame 1, and a ring-shaped pressing plate 6 larger in diameter
than the permanent magnet 4 is provided in the stepped portion 57. It is fitted.
Then, the screw 62 is screwed into the voice coil bobbin 5 through the screw hole 61 formed in
the presser plate 6, whereby the presser plate 6 is fixed to the voice coil bobbin 5, and the
permanent magnet is fixed by the fixed presser plate 6. 4 are fixed in the hollow portion 56 of
the voice coil bobbin 5.
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[0027]
The diaphragm 2 is made of a conductive material. In this example, the diaphragm 2 is made of a
conductive and nonmagnetic metal such as a copper plate or an aluminum plate. The diaphragm
2 can also be made of a magnetic material such as iron.
[0028]
The diaphragm 2 of this example is provided with a thin flat plate having the same shape as that
of the frame 1 and slightly larger than the frame 1 as a vibrating surface 2a. An annular wall
portion 21 is formed in the direction perpendicular to the vibrating surface 2 a of the vibrating
plate 2 from the peripheral edge of the vibrating surface 2 a of the vibrating plate 2. Further, at
appropriate positions of the wall portion 21, a plurality of attachment portions 22 projecting in
the direction orthogonal to the vibration surface 2a of the diaphragm 2 are provided, four in the
example of the figure. The mounting portion 22 is formed in the wall portion 21 of the
diaphragm 2 at the position of the diaphragm 2 corresponding to the position where the screw
holes 13 on the side surface of the frame 1 described above are formed. The screw hole 23 is
formed to be in communication with the screw hole 13.
[0029]
Then, as shown in FIG. 2, the screw 24 is screwed into the frame 1 through the screw holes 23
and 13, whereby the diaphragm 2 is fixed to the frame 1 at the wall portion 21. In this case, the
vibrating surface 2a of the vibrating plate 2 and the permanent magnet 4 are separated by an
amount corresponding to the vibration amplitude of the vibrating surface 2a.
[0030]
That is, the vibrating surface 2a is separated from the permanent magnet 4 so that the vibrating
surface 2a does not contact the permanent magnet 4 even at the maximum amplitude of the
vibrating surface 2a. In this case, in this example, an insertion member 15 made of, for example,
rubber is provided between the vibration surface 2 a of the vibration plate 2 and the frame 1.
The insertion member 15 is a member for determining the distance between the diaphragm 2
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and the frame 1.
[0031]
[Description of Vibration Principle of Speaker According to First Embodiment] In the speaker
having the above-described configuration, when an audio signal current flows through the voice
coil 3, the current flowing through the voice coil 3 flows through the vibration surface 2 a of the
diaphragm 2. An eddy current in the opposite direction is induced, and the eddy current cuts a
line of magnetic force from the permanent magnet 4 to generate a force that causes the
diaphragm 2 to vibrate in a direction orthogonal to the vibrating surface 2a. The vibrating
surface 2a of the plate 2 vibrates according to the audio signal.
[0032]
The vibration principle of the vibration surface 2 a of the diaphragm 2 will be described in more
detail with reference to FIGS. 3 and 4.
FIG. 3 is a cross-sectional view of a state in which the permanent magnet 4 is housed in the
hollow portion 56 of the voice coil bobbin 5 around which the voice coil 3 is wound, and FIG. 4
shows the current flowing through the voice coil 3 and the diaphragm 2a. It is a figure for
demonstrating the relationship with the eddy current induced in.
[0033]
The voice signal current flowing in the voice coil 3 flows in a direction from the front to the back
of the paper surface in a direction perpendicular to the paper surface in the cross section on the
left side of the voice coil 3 in the cross section shown in FIG. In the cross-section on the right side
of 3, it is assumed that the direction is perpendicular to the paper and flows from the back to the
front of the paper. That is, in FIG. 4, the current flows in the voice coil 3 in the direction indicated
by the solid arrow 101.
[0034]
At this time, an eddy current is generated in the diaphragm 2 so as to prevent the change due to
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9
the audio signal current flowing through the voice coil 3, so the direction of the eddy current is
in the vicinity of the cross section on the left side of the voice coil 3. The direction is from the
back to the front of the paper, and in the vicinity of the right cross section of the voice coil 3, the
direction from the front to the back of the paper is perpendicular to the paper. Therefore, an
eddy current is generated in the diaphragm 2 in the direction indicated by the solid arrow 102 in
FIG.
[0035]
Then, due to the action of the eddy current and the magnetic line of force from the permanent
magnet 4, a force acts on the diaphragm 2 in the directions of solid arrows 103 a and 103 b in
FIG. 3.
[0036]
On the other hand, when the direction of the audio signal current flowing through the voice coil
3 is reversed and the direction shown by the broken arrow 104 in FIG. 4 is reached, the
diaphragm 2 is in the direction shown by the broken arrow 105 in FIG. Eddy current is
generated.
For this reason, in FIG. 3, the direction of the audio signal current flowing through the voice coil
3 and the direction of the eddy current generated in the diaphragm 2 are completely opposite to
those shown in FIG. In FIG. 3, a force acts in the direction of dashed arrows 106a and 106b.
[0037]
As described above, the vibration surface 2a of the diaphragm 2 vibrates according to the audio
signal, and the sound according to the audio signal is acoustically reproduced.
[0038]
In the loudspeaker according to the first embodiment, the magnetic field generated by the
permanent magnet 4 is generated in a relatively wide range, and the eddy current is also
generated in the diaphragm 2 in a relatively wide range. There is a feature that it is difficult to
get up.
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And there is an advantage that the configuration is simple, and therefore, it can be manufactured
inexpensively.
[0039]
Second Embodiment The speaker of the first embodiment described above has the following
problems.
[0040]
That is, when the vibrating surface 2a of the vibrating plate 2 vibrates in the direction
approaching the permanent magnet 4 by receiving a force in the direction of the solid arrows
103a and 103b, the magnetic lines of force from the permanent magnet 4 become large. When
vibrating in the direction away from the permanent magnet 4 in the direction of the arrows 106a
and 106b, the lines of magnetic force from the permanent magnet 4 become weak.
[0041]
As described above, in accordance with the vibration of the diaphragm 2, strong and weak lines
occur in the magnetic lines of force linking the eddy currents, so even-order distortion occurs in
the vibration of the diaphragm 2 and the acoustic quality is degraded. is there.
The speaker of the second embodiment solves the problem of even-order distortion.
[0042]
The loudspeaker according to the second embodiment will be described with reference to FIGS. 5
to 7.
FIG. 5 is an exploded perspective view of the thin flat panel loudspeaker according to the second
embodiment, FIG. 6 is a cross sectional view thereof, and FIG. 7 is a diagram for explaining its
vibration principle.
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11
[0043]
In FIGS. 5 to 7, the same components as those of the speaker described with reference to FIGS. 1
to 4 are denoted by the same reference numerals.
[0044]
In the speaker according to the second embodiment, the configuration of the voice coil bobbin 5
and the diaphragm 2 around which the frame 1 and the voice coil 3 are wound, and the
attachment of the voice coil bobbin 5 and the diaphragm 2 to the frame 1 are shown in FIG. The
configuration is the same as that of the loudspeaker according to the first embodiment described
above with reference to FIGS.
Therefore, in order to avoid repeated explanation, their explanation is omitted here.
[0045]
In the speaker of the second embodiment, the diaphragm 8 is also attached to the side opposite
to the surface of the frame 1 to which the diaphragm 2 is attached. In this example, the
diaphragm 8 is configured completely the same as the diaphragm 2. That is, the diaphragm 8 is
made of the same material as the diaphragm 2 and has the same dimensions including the shape.
In the second embodiment, as described above, the diaphragm 8 is made of a conductive and
nonmagnetic metal such as a copper plate or an aluminum plate. As described above, the
diaphragm 2 and the diaphragm 8 can also be made of a magnetic material such as iron.
[0046]
In the frame 1, screw holes 16 for fixing the diaphragm 8 are formed in the side surface portion.
[0047]
On the other hand, like the diaphragm 2, the diaphragm 8 is provided with a thin flat plate
slightly larger than the frame 1 as the vibration surface 8a.
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12
An annular wall portion 81 is formed in the direction orthogonal to the vibrating surface 8 a of
the vibrating plate 8 from the peripheral edge of the vibrating surface 8 a of the vibrating plate
8. Further, at appropriate positions of the wall portion 81, a plurality of attachment portions 82
projecting in the direction orthogonal to the vibration surface 8a of the diaphragm 8 are
provided, four in the example of the figure. The mounting portion 82 is formed on the wall
portion 81 of the diaphragm 8 at the position of the diaphragm 8 corresponding to the position
where the screw holes 16 on the side surface of the frame 1 described above are formed. The
screw holes 83 are formed to be in communication with the screw holes 16.
[0048]
Then, a screw (not shown) is screwed into the frame 1 through the screw holes 83 and 16,
whereby the diaphragm 8 is fixed to the frame 1 at the wall portion 81. In this case, the vibrating
surface 8a of the vibrating plate 8 and the permanent magnet 40 of this embodiment are
separated by an amount corresponding to the vibration amplitude of the vibrating surface 8a.
[0049]
That is, the vibrating surface 8a is separated from the permanent magnet 40 so that the vibrating
surface 8a does not contact the permanent magnet 40 even at the maximum amplitude of the
vibrating surface 8a. In this case, in this example, an insertion member 17 made of, for example,
rubber is provided between the vibration surface 8 a of the vibration plate 8 and the frame 1.
The insertion member 17 is a member for determining the distance between the diaphragm 8
and the frame 1.
[0050]
In this case, the insertion member 15 and the insertion member 17 have the same height. That is,
the vibrating surface 2a of the vibrating plate 2 and the vibrating surface 8a of the vibrating
plate 8 are equidistant from both end surfaces in the thickness direction of the permanent
magnet 40 of the second embodiment.
[0051]
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13
And in this 2nd embodiment, diaphragm 2 and diaphragm 8 are connected via connecting
member 7 in the central position of the oscillating face 2a and oscillating face 8a. In this
example, the connecting member 7 is made of a cylindrical nonmagnetic and nonconductive
material such as wood, and the length in the direction of the center line is the diaphragm 2 and
the diaphragm 8. Is chosen equal to the distance between
[0052]
As the permanent magnet 40 of the second embodiment, a disc-like one similar to that of the
permanent magnet 4 of the first embodiment described above is used. The center portion is
provided with a hollow portion 41 having a diameter larger than the diameter of the connection
member 7.
[0053]
Then, the connecting member 7 is inserted into the hollow portion 41, and the diaphragm 2 and
the diaphragm 8 are fixed to the connecting member 7, whereby the diaphragm 2 and the
diaphragm 7 are coupled.
For this connection, a screw insertion hole 25 is formed at the center position of the vibration
surface 2 a of the diaphragm 2, and a screw insertion hole 84 is formed at the center position of
the vibration surface 8 a of the diaphragm 8. ing.
[0054]
On the other hand, screw holes 71 having a predetermined depth from both end portions are
formed in the connecting member 7 at the center line position thereof.
[0055]
Then, as shown in FIG. 6, the screw 26 is screwed into the screw hole 71 of the connection
member 7 through the insertion hole 25, whereby the diaphragm 2 is coupled to the connection
member 7.
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14
Similarly, the screw 85 is screwed into the screw hole 71 of the connecting member 7 through
the insertion hole 84, whereby the diaphragm 8 is coupled to the connecting member 7.
[0056]
In the loudspeaker of this embodiment, for example, a high-power power amplifier 9 of 100 W is
provided on the frame 1. The input terminal of the power amplifier is connected to a speaker
terminal (not shown). Further, the output terminal of this power amplifier is connected to the
voice coil 3. Therefore, the audio signal input to the speaker terminal is amplified by the power
amplifier 9 and then supplied to the voice coil 3.
[0057]
The power amplifier 9 is designed in accordance with the characteristics of the loudspeaker of
this embodiment. Further, the power amplifier 9 is covered and shielded by a cover made of an
electromagnetic shielding member.
[0058]
The other configuration is the same as that shown in FIGS. 1 and 2 described above.
[0059]
As described above, according to the speaker of the second embodiment, the two diaphragms 2
and 8 are arranged on both sides of the frame on which the voice coil 3 and the permanent
magnet 40 are provided. The voice signal current flows through the voice coil 3 to generate eddy
currents in the diaphragms 2 and 8.
[0060]
For example, in the cross section on the left side of the voice coil 3 in the principle view of FIG. 7,
the direction of the current flowing through the voice coil 3 is perpendicular to the sheet and
flows from the front to the back of the sheet Now, consider the case where the direction is
perpendicular to the paper and flows from the back to the front of the paper.
[0061]
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15
At this time, an eddy current is generated in the diaphragm 2 and the diaphragm 8 so as to
prevent a change due to the audio signal current flowing through the voice coil 3. Then, the
direction perpendicular to the paper surface is from the back to the front of the paper, and in the
vicinity of the right cross section of the voice coil 3, it is perpendicular to the paper from the
front to the back of the paper.
[0062]
Then, due to the action of the eddy current and the magnetic line of force from the permanent
magnet 4, a force acts on the diaphragm 2 in the direction of the solid arrows 111a and 111b in
FIG.
In addition, a force acts on the diaphragm 8 in the direction of solid arrows 121a and 121b in
FIG.
[0063]
On the other hand, when the direction of the audio signal current flowing through the voice coil
3 is reversed, an eddy current is generated in the diaphragm 2 and the diaphragm 8 in the
direction opposite to that in FIG.
For this reason, in FIG. 7, the directions of the audio signal current flowing through the voice coil
3 and the eddy currents generated in the diaphragm 2 and the diaphragm 8 are completely
opposite to those shown in FIG. 7, a force acts in the direction of the broken arrows 112a and
112b, and a force acts on the diaphragm 8 in the direction of the broken arrows 122a and 122b
in FIG.
[0064]
As described above, the vibrating surface 2a of the diaphragm 2 and the vibrating surface 8a of
the diaphragm 8 vibrate according to the audio signal, and the sound according to the audio
signal is acoustically reproduced.
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At this time, when one of the diaphragms moves away from the permanent magnet and the
magnetic lines of force weaken, the other diaphragm approaches the permanent magnet and the
magnetic lines of force become strong, and one of the diaphragms approaches the permanent
magnet and the magnetic lines of force Becomes stronger, the other diaphragm moves away from
the permanent magnet, and the lines of magnetic force become weaker.
[0065]
Therefore, both diaphragms 2 and 8 vibrate so as to compensate for the change in strength of
the magnetic lines of force accompanying their respective vibrations, so that even-order
distortion of each diaphragm 2 and 8 is eliminated. Works.
That is, in the loudspeaker of this embodiment, even-order vibration distortion can be removed
by providing the two diaphragms 2 and 8.
[0066]
In the second embodiment described above, the diaphragm 2 and the diaphragm 8 are made of
the same material and have the same dimensions. However, the purpose is to reduce and
eliminate even-order vibration distortion of the diaphragm 2. The diaphragm 8 may be smaller
than the diaphragm 2. In that case, the diaphragm 8 may be attached to and fixed to the
connection member 7 and may not be fixed to the frame 1.
[0067]
In the above description, the permanent magnet is disposed in the hollow portion of the winding
shaft of the voice coil bobbin so that the voice coil is wound on the outer side of the permanent
magnet. It is also possible to configure the wound voice coil bobbin to be disposed in the hollow
portion of the permanent magnet.
[0068]
[Configuration of Speaker System to which Speaker of Second Embodiment is Applied] In the
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speaker of the second embodiment described above, since the diaphragm 2 and the diaphragm 8
are made of the same material and have the same dimensions, vibration is generated. Due to the
vibration of the plate 8, it is possible to obtain a reproduced sound in the reverse phase to the
reproduced sound due to the vibration of the diaphragm 2.
Therefore, by utilizing this, it is possible to realize a speaker system capable of performing stereo
reproduction of left and right two channels only by arranging the speakers on a straight line
connecting the front and back of the listener.
[0069]
FIG. 8 is a layout diagram of a speaker for explaining a first example of the speaker system, and
FIG. 9 is a block diagram for explaining an apparatus for generating an audio signal to be
supplied to speakers constituting the speaker system. It is.
[0070]
In the speaker system of this example, for example, a thin flat plate speaker 200 having the
structure of the embodiment described with reference to FIGS. 5 to 7 described above and a
speaker unit for normal full band are attached to a baffle plate. It is configured using a general
type speaker 300 such as a type or bass reflex type.
[0071]
Then, in the example of FIG. 8, in the thin flat loudspeaker 200, the vibration direction of the
diaphragm 2 and the diaphragm 8 is substantially orthogonal to the straight line connecting the
front and back of the listener 400 in front of the listener 400. Arrange as.
Further, the general type speaker 300 is arranged so that the diaphragm of the speaker unit 301
is directed to the listener 400 and the vibration direction of the diaphragm is a linear direction
connecting the front and back of the listener 400.
[0072]
Then, a signal (L + R) of the sum of the audio signal L of the left channel and the audio signal R of
the right channel is supplied to the general type speaker 300, and the thin flat loudspeaker 200
is an audio of the right channel. A signal (LR) which is a difference from the signal R is supplied.
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[0073]
That is, as shown in FIG. 9, the audio signal L of the left channel and the audio signal R of the
right channel are supplied to the adapter 500 for speaker drive signal generation of this example.
The adapter 500 includes an adder circuit 501 and a subtractor circuit 502, and the audio signal
L of the left channel and the audio signal R of the right channel are both supplied to the adder
circuit 501 and the subtractor circuit 502.
[0074]
Therefore, a sum signal (L + R) is obtained from the adder circuit 501, and the sum signal (L + R)
is supplied to the general speaker 300 through the power amplifier 503.
Also, a difference signal (LR) is obtained from the subtraction circuit 502, and the signal (LR) of
this difference is supplied to the thin flat plate speaker 200 through the power amplifier 504.
The power amplifier 504 is omitted when the speaker 200 is provided with the power amplifier
9.
[0075]
In such a configuration, from the general type speaker 300, the sum of the sound of the left and
right channels according to the sum signal (L + R) is emitted and reaches the left and right ears of
the listener 400.
[0076]
On the other hand, in the flat and thin speaker 200, the difference between the left and right
channels' sounds according to the difference signal (LR) is emitted from the diaphragm 2 and
reaches the left ear of the listener.
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Further, from the diaphragm 8, the difference in sound of the left and right channels according to
the signal (R-L) of the difference in phase opposite to that of the diaphragm 2 is emitted and
reaches the right ear of the listener.
[0077]
Therefore, in the left ear of the listener, sound synthesis of (L + R) + (L−R) = 2L is performed to
listen to the sound L of the left channel. Also, in the right ear of the listener, sound synthesis of (L
+ R) + (R−L) = 2R is performed, and the sound R of the right channel is listened to.
[0078]
Thus, in the speaker system of this example, by arranging the two speakers so as to overlap the
front of the listener, it is possible to listen to the stereo sound of the left and right channels.
Therefore, even in a space where two speakers for the left and right channels can not be
arranged left and right, according to the speaker system of this example, stereo sound can be
listened to.
[0079]
Although the example of FIG. 8 is a case where both the general type speaker 300 and the thin
flat plate speaker 200 are disposed in front of the listener, as shown in FIG. 10, the general type
speaker 300 is an example of FIG. The thin flat loudspeaker 200 is arranged in the same manner
as in the case, and the thin flat loudspeaker 200 is a vibration of the diaphragm 2 and the
diaphragm 8 on the straight line connecting the front and back of the listener as in the case of
FIG. Even if the direction is arranged to be substantially orthogonal to the straight line
connecting the front and back of the listener 400, the left channel and the right ear of the
listener are acoustically synthesized in the same manner as described above. And the sound of
the right channel are separated and listened.
[0080]
As described above, according to the present invention, it is possible to provide a thin flat-plate
speaker which is hard to cause divided vibration and which has a simple structure.
11-05-2019
20
Furthermore, according to the present invention, it is possible to provide a thin flat-plate speaker
from which even-order vibration distortion has been removed.
11-05-2019
21
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