JP2003102088

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DESCRIPTION JP2003102088
[0001]
BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a
planar acoustic transducer such as a planar speaker, a planar microphone and a planar speaker
which can also be used as a microphone, and in particular, the area of the diaphragm can be
enlarged. The present invention relates to a flat acoustic transducer.
[0002]
2. Description of the Related Art FIG. 11 is a cross-sectional view showing the basic configuration
of a conventional flat loudspeaker.
[0003]
As shown in FIG. 11B, in the conventional planar speaker, one yoke 132 made of a magnetic
material is separated by a predetermined distance so that the polarities are alternately reversed
in the direction along one side of the yoke 132. A plurality of magnet arrays comprising a
plurality of permanent magnets M arranged to be adjacent to one another is provided.
[0004]
The plurality of permanent magnet arrays are spaced apart twice as far apart as the permanent
magnets M in the array, and the corresponding permanent magnets M of the adjacent magnet
arrays have the same polarity.
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[0005]
Further, in the other yoke 122 made of a magnetic material, a plurality of permanent magnets m
in the direction parallel to the magnet row of the yoke 132 is the same as the interval of the
permanent magnets M at a portion facing the middle portion of the magnet row of the yoke 132
A plurality of magnet arrays arranged at intervals are fixed.
[0006]
The polarities of the permanent magnets m of this magnet array are arranged in the opposite
order to the magnet arrays provided in the yoke 132, and opposite to the polarity of the pole
face of the permanent magnet M closest to the permanent magnet m when assembled as a
speaker. It is arranged to be polar.
[0007]
As shown in FIG. 11A, a diaphragm 126 is disposed between the yoke 122 and the yoke 132.
[0008]
On the diaphragm 126 is arranged a coil group in which a plurality of coil pairs 128 formed of a
pair of coils formed in a spiral and arranged on both the front and back sides are arranged
corresponding to the permanent magnets m and M respectively. It is done.
[0009]
Since this flat speaker can form a magnetic path without connecting facing yokes, it has the
feature that manufacturing cost can be reduced.
[0010]
The magnetic field H in the region between the permanent magnets m and M closest to each
other is directed in a direction substantially parallel to the diaphragm surface and is linked to the
coil pair 128.
[0011]
When a current I in a predetermined direction is applied to the coil pair 128, current flows in the
same direction in adjacent portions of the adjacent coil pair 128 from the inner circumference to
the outer circumference, and all the coil pairs 128 have the same direction and a diaphragm film
The diaphragm 126 is displaced in the direction perpendicular to the film surface so as to receive
the force F in the direction perpendicular to the surface.
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[0012]
Thus, by energizing the coil pair 128 with an electrical signal representing the sound to be
generated, the diaphragm 126 vibrates in response to the electrical signal to generate an
acoustic signal.
[0013]
However, in the above-mentioned conventional flat type speaker, as shown in FIG. 11 (B) or FIG.
11 (C), in the yoke 132, the number of N poles of the permanent magnet M and the number of S
poles in the yoke 132. In the yoke 122, the number of N poles and the number of S poles of the
permanent magnet m are unbalanced, which causes a problem of large magnetic flux leakage.
[0014]
Therefore, in order to reduce magnetic flux leakage, as shown in FIG. 12, the first magnet array
123 and the first magnet array provided alternately in the N pole and the S pole in the yoke 122
are adjacent to each other. A first magnet group 125 composed of a second magnet array 124
having different magnetic poles is provided at a predetermined interval, and a yoke 132 is
provided with a third magnet array 129 alternately provided with an N pole and an S pole. A
second magnet group 133 composed of fourth magnet arrays 130 having mutually different
magnetic poles adjacent to the third magnet array is provided at a predetermined interval, and
the number of N poles and the number of S poles in each yoke A configuration is considered in
which the number is balanced to reduce the magnetic flux leakage.
[0015]
On the other hand, flat-panel speakers output flat-wave sounds with little attenuation, so they do
not feel loud at close positions, and they can hear sounds that are as clear as close positions even
at distant positions. It has a feature.
[0016]
For this reason, it is suitable when transmitting a sound to a distant position in a classroom, a
hall or the like.
[0017]
However, in the case of a flat speaker, when it is desired to transmit a large sound away or to
lower the reproduction limit of the bass, the area of the diaphragm needs to be increased
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accordingly, but as the area of the diaphragm is increased. The area of the yoke also increases.
[0018]
However, in the flat loudspeaker having the structure shown in FIG. 12, it has been found that
the following problems occur as the yoke area increases.
[0019]
That is, as shown in FIG. 12, in this flat speaker, since the permanent magnet M of the yoke 122
is opposed to the yoke 132 and the permanent magnet M of the yoke 132 is opposed to the yoke
122, The attraction force of the opposing permanent magnet M acts.
[0020]
For this reason, when the yokes 122 and 132 are enlarged, the attraction force is increased as
the number of permanent magnets M is increased, and the yokes 122 and 132 are bent by the
increased attraction force.
[0021]
In order to suppress the curvature of the yokes 122 and 132, a method of thickening the yokes
122 and 132 can be considered, but there is a problem that the weight and thickness of the flat
speaker increase.
[0022]
For this reason, there is a limit to the increase in size of the yokes 122 and 132.
[0023]
In addition, weakening the force of the permanent magnet M or widening the distance between
the permanent magnet M and the facing yokes 122 and 132 only causes the deterioration of the
efficiency.
[0024]
The present invention has been made to solve the above-described conventional problems, and
an object of the present invention is to provide a flat acoustic transducer that can suppress the
curvature of the yoke and can be enlarged.
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[0025]
According to the first aspect of the present invention, there is provided a first yoke comprising a
magnetic body formed in a flat plate shape, and a flat plate which is disposed parallel to the first
yoke at an interval. And a diaphragm disposed in parallel between the first yoke and the second
yoke, and a magnetic pole disposed on the diaphragm side of the first yoke, Is directed to the
diaphragm side, and a first magnet array in which N and S poles are alternately provided along a
predetermined direction, and parallel to the first magnet array, the magnetic pole is directed to
the diaphragm A first magnet group including a second magnet array in which N poles and S
poles are alternately provided along a predetermined direction, and magnetic poles adjacent to
each other are different from the first magnet array; And the diaphragm side of the second yoke
A third magnet array in which magnetic poles are directed to the diaphragm side and N and S
poles are alternately provided along a predetermined direction, and the magnetic poles are
provided in parallel with the third magnet array A fourth magnet array having magnetic poles
directed to the side and alternately provided with an N pole and an S pole along a predetermined
direction, and magnetic poles adjacent to each other being different from the third magnet array;
A second magnet group provided close to a direction orthogonal to the predetermined direction
of one magnet group, and the diaphragm provided, N adjacent to each other of the first magnet
group and the second magnet group A conductor extending in a direction intersecting with the
direction of the magnetic field between the pole and the south pole, and at least one of the first
yoke and the second yoke to pass the sound generated by the vibration of the diaphragm Flat
acoustic variation with through holes A device, wherein at least one of the first yoke and the
second yoke is disposed to face at least one of the first magnet group and the second magnet
group; A repelling magnet for obtaining repulsive force is provided to face at least one of the N
pole and the S pole of the magnet group and the N pole and the S pole of the second magnet
group.
[0026]
Next, the operation of the flat acoustic transducer according to claim 1 will be described.
[0027]
On one surface of the first yoke, the magnetic pole is directed to the diaphragm side, and the first
magnet row provided with N poles and S poles alternately provided along a predetermined
direction, and provided in parallel with the first magnet row And the N pole and the S pole are
alternately provided along a predetermined direction, and the first magnet row is composed of a
second magnet row different in magnetic poles adjacent to each other. A first magnet group is
provided.
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[0028]
That is, the first magnet group is formed long in a predetermined direction, and the N pole and
the S pole are arranged in a staggered manner.
[0029]
Similarly, on one surface of the second yoke, a third magnet array having a magnetic pole
directed to the diaphragm side and N and S poles alternately provided along a predetermined
direction, and a third magnet array A fourth magnet array provided parallel to orient the
magnetic poles toward the diaphragm and having N poles and S poles alternately arranged along
a predetermined direction, and having a third magnet array different from each other in adjacent
magnetic poles A second group of magnets is provided.
[0030]
That is, the second magnet group is also formed long in a predetermined direction, and the N
pole and the S pole are arranged in a staggered manner.
[0031]
Further, the second magnet group is provided close to a direction perpendicular to the
predetermined direction of the first magnet group, and the magnetic poles adjacent to each other
are different from the first magnet array.
[0032]
For this reason, when looking at the first yoke and the second yoke from the diaphragm, the N
pole and the S pole become a zigzag across the entire surface of the first yoke and the second
yoke, and the N pole and the S pole adjacent to each other are staggered. The magnetic field
between the poles points in a direction substantially parallel to the diaphragm surface.
[0033]
The diaphragm disposed between the first yoke and the second yoke is provided with a coil
extending in a direction intersecting the magnetic lines of force between the N pole and the S
pole adjacent to each other. When energized, the direction of the force that the current receives
from the magnetic field is in a direction substantially orthogonal to the diaphragm surface,
whereby the diaphragm can be vibrated in a direction orthogonal to the surface of the
diaphragm.
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[0034]
The sound generated by vibration of the diaphragm is radiated through a through hole provided
in at least one of the first yoke and the second yoke.
[0035]
Here, the first magnet group is opposed to the portion of the second yoke where the second
magnet group is not disposed, and the second magnet group is not disposed of the first magnet
group of the first yoke. Since the first magnet group attracts the second yoke and the second
magnet group tries to adsorb the first yoke because it faces the part, the repelling magnet is the
N pole of the first magnet group. And S pole, and generates repulsive force facing at least one of
N pole and S pole of the second magnet group, so that the first yoke by the magnetic force of the
first magnet group and the second magnet group, and The curvature of the second yoke can be
suppressed, and the area of the first yoke, the second yoke, and the diaphragm can be increased.
[0036]
The invention according to claim 2 is the planar acoustic transducer according to claim 1,
wherein a plurality of the repelling magnets are provided substantially at the center of at least
one of the first yoke and the second yoke. It is characterized by
[0037]
Next, the operation of the flat acoustic transducer according to claim 2 will be described.
[0038]
The magnetic forces of the first magnet group and the second magnet group cause the first yoke
and the second yoke to bend so that the central portions are closest to each other, so that the
first yoke and the second yoke are not bent. It is effective to provide a plurality of repelling
magnets at the central portion rather than near the outer periphery.
That is, the number of repelling magnets can be minimized.
[0039]
BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an example of a flat speaker as a
flat acoustic transducer will be described in detail with reference to the drawings.
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[0040]
As shown in FIG. 1, the flat speaker 10 according to the present embodiment includes a first yoke
12, a spacer 14, a diaphragm 16, a spacer 18, and a second yoke 20 in order.
[0041]
As shown in FIG. 2, the first yoke 12 is made of a magnetic material, and is formed in a
rectangular flat plate elongated in the Y direction in the drawing.
[0042]
As shown in FIGS. 2 and 3, on the diaphragm side surface of the first yoke 12, a tetragonal
permanent magnet M with the S pole directed to the diaphragm side and a permanent magnet M
with the N pole directed to the diaphragm side And a first magnet group 26 consisting of two
magnet arrays of a first magnet array 22 and a second magnet array 24 alternately arranged at
regular intervals in the X direction, which is a direction orthogonal to the Y direction. A plurality
of lines (eight lines in the present embodiment) are provided at regular intervals in the Y
direction.
[0043]
As shown in FIG. 2, the pole face of the permanent magnet M of the first magnet row 22 on the
diaphragm side and the pole face of the permanent magnet M of the second magnet row 24
adjacent thereto on the diaphragm side have the polarity ( In the figure, S and N) are different.
[0044]
As shown in FIG. 4, the second yoke 20 is made of a magnetic material, and is formed in a
rectangular flat plate elongated in the Y direction in the drawing.
[0045]
As shown in FIGS. 3 and 4, on the diaphragm side surface of the second yoke 20, a quadrangular
permanent magnet M with the S pole facing the diaphragm side and a permanent magnet M with
the N pole facing the diaphragm side A second magnet group 32 composed of two magnet arrays
of a third magnet array 28 and a fourth magnet array 30 alternately arranged at regular intervals
in the X direction, in which X is a direction orthogonal to the Y direction, A plurality of rows
(seven rows in this embodiment) are provided at regular intervals in the Y direction.
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[0046]
As shown in FIG. 4, the pole face of the permanent magnet M on the diaphragm side of the third
magnet row 28 and the pole face of the permanent magnet M on the diaphragm side of the
fourth magnet row 30 adjacent thereto have polarities ( In the figure, S and N) are different.
[0047]
As shown in FIG. 3, the first magnet group 26 and the second magnet group 32 are disposed at a
constant distance in the Y direction, and the diaphragm of the permanent magnet M of the first
magnet group 26 The polarity is different between the magnetic pole surface on the side and the
magnetic pole surface on the diaphragm side of the permanent magnet M of the second magnet
group 32 adjacent thereto.
[0048]
Further, each pole face of each permanent magnet M of the first magnet group 26 faces a portion
of the second yoke 20 where the permanent magnet M is not disposed, and each permanent
magnet of the second magnet group 32 Each magnetic pole surface of M is opposed to the
portion where the permanent magnet M of the first yoke 12 is not disposed.
[0049]
The permanent magnets M of the first magnet group 26 and the permanent magnets M of the
second magnet group 32 are arranged at equal intervals in the arrow Y direction and the arrow X
direction.
[0050]
As shown in FIGS. 2 and 5, in the vicinity of the center of the diaphragm-side surface of the first
yoke 12, a rectangular permanent magnet for repulsion with the magnetic pole surface facing the
diaphragm is disposed between the first magnet group 26. Four magnets RM are respectively
arranged.
[0051]
These repelling permanent magnets RM are disposed at positions facing the permanent magnets
M of the second yoke 20, and the polarity on the diaphragm side is the magnetic poles of the
permanent magnets M of the second yoke 20 facing this. The repelling permanent magnets RM
and the permanent magnets M of the second yoke 20 opposed to the repelling permanent
magnets RM are set to the same polarity so as to repel each other.
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[0052]
As shown in FIGS. 2 and 4, a large number of holes 33 are formed in a matrix on each of the first
yoke 12 and the second yoke 20.
[0053]
As shown in FIGS. 1, 3 and 5, the diaphragm 16 is disposed between the first yoke 12 and the
second yoke 20 via the spacer 14 and the spacer 18.
[0054]
Each of the spacer 14 and the spacer 18 has a rectangular frame shape, and the vicinity of the
outer periphery of the diaphragm 16 is sandwiched by the spacer 14 and the spacer 18.
[0055]
As shown in FIGS. 1, 2, 4 and 6, the first yoke 12 has a plurality of screw holes 12A and holes
12B along the outer periphery, and the spacer 14 has a plurality of holes 14A along the outer
periphery. A plurality of holes 16A are formed along the outer periphery, a plurality of holes 18A
are formed along the outer periphery of the spacer 18, and a hole 20A is formed along the outer
periphery of the second yoke 20.
[0056]
As shown in FIGS. 3 and 5, the second yoke 20, the spacer 18, the diaphragm 16, the spacer 14,
and the first yoke 12 are a hole 20A, a hole 18A, a hole 16A, and a hole 14A (FIGS. 3 and 4). At
5, the holes 34 are integrally fixed by being screwed into the screw holes 12A.
[0057]
The hole 12B of the first yoke 12 is used for attachment.
[0058]
The diaphragm 16 is spaced apart from the respective pole faces of the permanent magnet M
and the repelling permanent magnet RM by the spacer 14 and the spacer 18.
[0059]
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The diaphragm 16 is made of a polymer film such as polyimide or polyethylene terephthalate.
[0060]
The effective diaphragm area of the diaphragm 16 of the present embodiment is about 200 mm
× about 300 mm.
[0061]
As shown in FIG. 6, a first conductor 36 and a second conductor 38 are respectively provided on
one side of the diaphragm 16 and on both sides of the central portion in the X direction.
[0062]
The pattern of the first conductor 36 and the second conductor 38 is schematically shown in FIG.
[0063]
As shown in FIGS. 7 and 8, the first conductor 36 and the second conductor 38 are parallel to
each other, and as shown in FIG. 8, around the outer periphery of the permanent magnet M and
the permanent magnet M and the permanent magnet, respectively. It is disposed between M and
M, and extends from one side to the other side of the Y direction in a zigzag manner along the
longitudinal direction (the arrow Y direction) of the magnet array.
[0064]
As shown in FIGS. 7 and 9, the first conductor 36 and the second conductor 38 are connected
such that current flows in the same direction (the direction of the current is shown in FIG. 7).
[0065]
The first conductor 36 and the second conductor 38 may be connected in series as shown in FIG.
7 or may be connected in parallel.
[0066]
In any case, the first conductor 36 and the second conductor 38 are connected to an amplifier
(not shown) so that current flows in the same direction.
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[0067]
Such a first conductor 36 and a second conductor 38 are formed by forming a metal thin film of
copper or aluminum on the diaphragm 16 by a method such as laminating, vapor deposition,
adhesion or the like, and etching this metal thin film be able to.
[0068]
As shown in FIG. 8, in the first conductor 36 and the second conductor 38, the width direction of
each of the wide portion extending linearly in the arrow X direction and the wide portion
extending linearly in the arrow Y direction In the central portion, an elongated region 40 not
provided with a metal thin film is provided along the extension direction of the conductor (the
direction orthogonal to the direction of the magnetic field), and the conductor is divided into two
in parallel.
[0069]
Thereby, it is possible to suppress the eddy current generated when the high frequency current
flows.
The number of divisions of the conductor may be three or more.
[0070]
Further, the wide portions extending linearly in the arrow X direction of the first conductor 36
and the second conductor 38 and the wide portions extending rectilinearly in the arrow Y
direction are each parallel to the side of the permanent magnet M. .
[0071]
Further, the wide portion linearly extending in the arrow X direction and the wide portion
extending linearly in the arrow Y direction are connected at the shortest distance.
[0072]
Incidentally, the width of the pattern of the first conductor 36 and the width of the pattern of the
second conductor 38 in the present embodiment are respectively about 1 mm in a thin portion
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and about 2 mm in a thick portion.
(Operation) Next, the operation of the flat speaker 10 of the present embodiment will be
described.
[0073]
As shown in FIGS. 7 and 9, when the current I (the direction is shown by the arrow) is applied to
the first conductor 36 and the second conductor 38, the first conductor 36 and the second
conductor 38 The force (electromagnetic force) F in the direction orthogonal to the direction of
the magnetic field H and the current I (in this case, the direction of the force F is on the second
yoke 20 side) acts according to
[0074]
In addition, when the current I is applied to the first conductor 36 and the second conductor 38
in the direction opposite to that in FIGS. 7 and 9, the first conductor 36 and the second
conductor 38 receive the first yoke 12. A force F acting to the side acts.
[0075]
Therefore, the diaphragm 16 provided with the first conductor 36 and the second conductor 38
by flowing an electrical signal representing the sound desired to be generated to the first
conductor 36 and the second conductor 38 generates the flowed electricity. It vibrates according
to the signal.
[0076]
The sound generated by the vibration of the diaphragm 16 passes through the holes 33 formed
in the first yoke 12 and the second yoke 20 and is radiated to the outside of the yoke.
[0077]
Since the diaphragm 16 is flat and vibrates in the direction perpendicular to the film surface, the
sound radiated from the diaphragm 16 is a plane wave.
[0078]
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In the present embodiment, in the first yoke 12 and the second yoke 20, the polarities of the
adjacent permanent magnets M are set alternately, and the number of N poles on the yoke side
and the number of S poles are the same. Therefore, leakage of magnetic flux can be reduced.
For this reason, it is not necessary to provide a separate magnetic shield.
[0079]
Here, the permanent magnet M of the first yoke 12 is opposed to the portion where the
permanent magnet M of the second yoke 20 is not disposed, and the permanent magnet M of the
second yoke 20 is of the first yoke 12. The permanent magnet M of the first yoke 12 attracts the
second yoke 20 and the permanent magnet M of the second yoke 20 is the first yoke 12 because
it faces the portion where the permanent magnet M is not disposed. Of the first yoke 12 and the
second yoke 20, but the repelling permanent magnet RM provided near the center of the first
yoke 12 is a permanent magnet of the second yoke 20. Since a repulsive force which is a force
opposite to the attracting force is generated opposite to M, the curvature of the first yoke 12 and
the second yoke 20 can be suppressed.
[0080]
Therefore, in the flat speaker 10 according to the present embodiment, the area of each of the
first yoke 12, the second yoke 20, and the diaphragm 16 can be made larger than that of the
conventional product, whereby the output can be made larger.
[0081]
Further, since the area of the diaphragm 16 can be increased to lower the reproduction limit of
the low band, it can be used, for example, as a woofer of a multi-way speaker system.
[0082]
In the present embodiment, the first magnet group 26 and the second magnet group 32 are
configured by arranging the plurality of permanent magnets M at predetermined intervals. The
second magnet group 32 may be a single long permanent magnet 42 in which the S pole and the
N pole are magnetized in a staggered manner as shown in FIG. 10, respectively.
[0083]
Further, although the repelling permanent magnet RM is provided on the first yoke 12 in the
present embodiment, it may be provided on the second yoke 20.
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[0084]
In addition, since the first conductor 36 and the second conductor 38 are provided two by two in
the diaphragm 16 of the present embodiment, by connecting these in parallel or in series, a unit
of the flat speaker 10 The impedance as can be changed variously.
[0085]
In addition, the width of the pattern of the first conductor 36 and the width of the pattern of the
second conductor 38 are about 1 to 2 mm, which is extremely wide with respect to the width (for
example, 200 μm) of the conductor of the conventional flat speaker It is set.
[0086]
For this reason, the ratio affected by the variation (for example, ± 20 μm) of the pattern width
due to the etching is very small, and the variation of the resistance can be reduced.
[0087]
Moreover, the flat speaker 10 of this embodiment can also be used as a microphone.
[0088]
As described above, the flat acoustic transducer according to the first aspect of the present
invention has an excellent effect that enlargement can be achieved while suppressing the
curvature of the yoke.
[0089]
The flat acoustic transducer according to claim 2 has an excellent effect that the number of
repelling magnets can be minimized.
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