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JPWO2013076914

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DESCRIPTION JPWO2013076914
Abstract A loudspeaker having an elongated structure, and a frame and a flat plate perpendicular
to the vibration direction have a longitudinally long shape having a long side and a short side,
and a diaphragm having a hollow structure and a diaphragm are vibratably supported. And at
least one cylindrical voice coil bobbin connected through the diaphragm, the voice coil fixed to
the voice coil bobbin inside the hollow structure of the diaphragm, and the inside of the voice coil
bobbin And a magnetic circuit for driving the voice coil.
Speaker and electronic device equipped with the speaker
[0001]
TECHNICAL FIELD The present disclosure relates to a speaker, and more particularly to a
speaker for achieving thinning.
[0002]
In recent years, with the spread of so-called high vision and wide vision televisions, etc., the
screen of the television is becoming generally wide.
On the other hand, narrow and thin television sets as a whole are desired from the domestic
housing situation.
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1
[0003]
Since a speaker unit for television (hereinafter referred to as a speaker) is usually attached to
both sides of a display such as a plasma display or a liquid crystal display, it contributes to
increasing the width of the television set. For this reason, conventionally, a speaker having a
slender shape such as a rectangular shape or an elliptical shape has been used for television. In
addition, the horizontal width of the display is required to be smaller and smaller. In addition,
since flat-screen TVs using plasma displays and liquid crystal displays are increasing, thinning of
the speakers is further required. Furthermore, there is a demand for the speaker to have a high
sound quality corresponding to the high image quality of the screen.
[0004]
As a prior art document related to the present disclosure, for example, Patent Document 1 is
known, and Patent Document 1 shows the structure of a speaker having a conventional
elongated structure.
[0005]
JP-A-7-298389
[0006]
However, in the conventional loudspeaker having the elongated structure, since the driving
method of driving the central portion of the elongated diaphragm is adopted, split resonance
easily occurs in the longitudinal direction of the diaphragm.
As a result, the frequency characteristic related to the reproduction sound pressure level is a
characteristic that causes a peak dip in the middle and high frequencies, resulting in the
deterioration of the sound quality.
In addition, in order to make it difficult to cause longitudinal resonance with the same opening
area, it is necessary to make the diaphragm deep in shape (cone shape), and there is a problem
that the depth of the speaker can not be reduced. .
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[0007]
The present disclosure has been made in view of the above-described problems, and has an
object to provide a speaker that can be thinned while having an elongated structure and that is
further excellent in sound quality.
[0008]
A speaker having an elongated structure, and a frame and a flat plate perpendicular to the
vibration direction have a longitudinally long shape having a long side and a short side, and a
diaphragm having a hollow structure and a diaphragm are vibratably supported on the frame An
edge to be fixed, at least one cylindrical voice coil bobbin connected through the diaphragm, a
voice coil fixed to the voice coil bobbin inside the hollow structure of the diaphragm, and an
inside of the voice coil bobbin And a magnetic circuit for driving the voice coil.
[0009]
According to the present disclosure, it is possible to provide a thin speaker with excellent sound
quality that can obtain flat frequency characteristics while having an elongated structure, and
that can be further reduced in thickness.
[0010]
FIG. 1A is a top view of the speaker in the first embodiment.
FIG. 1B is a schematic cross-sectional view taken along line A-A 'of FIG. 1A.
FIG. 1C is a schematic cross-sectional view taken along line B-B 'of FIG. 1A.
FIG. 2A is a top view of the diaphragm in the first embodiment. FIG. 2B is a schematic crosssectional view taken along line E-E 'of FIG. 2A. FIG. 2C is a schematic cross-sectional view taken
along line F-F 'of FIG. 2A. FIG. 3 is a perspective view of the voice coil and the voice coil bobbin in
the first embodiment. FIG. 4 is a perspective view of the magnetic circuit in the first embodiment.
FIG. 5 is a perspective view of a component configuration of the speaker in the first embodiment.
FIG. 6A is a hollow semicircular cross-sectional shape model diagram. FIG. 6B is a hollow circular
cross-sectional shape model diagram. FIG. 7 is a view showing calculated values of moment of
inertia, radius of rotation, and cross-sectional area of each of the cross-sectional shapes of a
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hollow circle and a hollow semicircle. FIG. 8 is a diagram showing analysis results of resonance
frequencies of natural vibration modes of a diaphragm having a hollow circular shape and a
hollow semicircular shape in cross section. FIG. 9A is a top view of the diaphragm in the second
embodiment. FIG. 9B is a cross-sectional view of the diaphragm in the longitudinal direction
according to the second embodiment. FIG. 10A is a top view of a loudspeaker according to
Embodiment 3. FIG. FIG. 10B is a schematic cross-sectional view taken along line G-G 'of FIG.
10A. 11A is a top view of a speaker according to Embodiment 3. FIG. 11B is a schematic crosssectional view taken along the line H-H 'of FIG. 11A. FIG. 12A is a characteristic diagram in the
case of two-point drive controlling the first resonance mode. FIG. 12B is a characteristic diagram
in the case of four-point drive which controls both the first and second resonance modes. FIG.
12C is a characteristic diagram in the case of center drive. FIG. 13 is a perspective view of the
magnetic circuit in the fifth embodiment. FIG. 14 is a cross-sectional view of the speaker
according to the fifth embodiment in the short direction. FIG. 15 is a perspective view of the
magnetic circuit in the sixth embodiment. FIG. 16 is a cross-sectional view in the short direction
of the speaker according to the sixth embodiment. FIG. 17 is a perspective view of a component
structure of the speaker in the sixth embodiment. FIG. 18 is a diagram of a mobile information
terminal device. FIG. 19 is a diagram of an image display device. FIG. 20 is a mounting view of
the in-vehicle speaker. FIG. 21A is a top view of a conventional speaker. FIG. 21B is a crosssectional view in the I-I ′ direction of FIG. 21A. 21C is a cross-sectional view in the direction of
J-J 'in FIG. 21A. FIG. 22 is a sound pressure frequency characteristic diagram of a conventional
speaker.
[0011]
A conventional speaker of elongated structure shown in Patent Document 1 will be described
with reference to the drawings. FIG. 21A is a plan view of a conventional elongated speaker
1000. FIG. 21B is a schematic cross-sectional view of FIG. 21A cut in the longitudinal direction (II ') and viewed from arrow i. FIG. 21C is a schematic cross-sectional view as sectioned in the
lateral direction (J-J ') and viewed from the arrow j. The conventional elongated speaker 1000
shown in FIGS. 21A to 21C includes a magnet 1001, a plate 1002, a yoke 1003, a frame 1004, a
voice coil bobbin 1005, a voice coil 1006, a damper 1007, and a diaphragm 1008. A dust cap
1009 and an edge 1010 are provided. The arrangement of the main components will be
described below.
[0012]
The voice coil 1006 is a winding of a conductor such as copper or aluminum, and is fixed to one
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of the cylindrical voice coil bobbins 1005. The voice coil 1006 is disposed by the magnet 1001
in a magnetic gap formed between the plate 1002 and the yoke 1003. Further, a diaphragm
1008 is fixed to the other of the voice coil bobbin 1005. Furthermore, the voice coil bobbin 1005
is fixed by a damper 1007. The damper 1007 is connected to the frame 1004.
[0013]
The plate 1002 is inside the voice coil bobbin 1005, and is disposed at a place where the voice
coil 1006 is fixed. A magnet 1001 is disposed below the plate 1002, and a yoke 1003 is
disposed so as to partially surround the magnet 1001.
[0014]
The planar shape of the diaphragm 1008 is an ellipse or a substantially ellipse. Also, the
diaphragm 1008 has a so-called cone shape having a slope toward the center. As a material of
the diaphragm 1008, cone paper or the like is used. Further, a dust cap 1009 is fixed to a central
portion of the diaphragm 1008.
[0015]
The edge 1010 has an annular planar shape and a semicircular cross section. The inner
peripheral portion of the edge 1010 is fixed to the outer peripheral portion of the diaphragm
1008, and the outer peripheral portion of the edge 1010 is fixed to the frame 1004.
[0016]
Next, the operation of the conventional elongated speaker 1000 configured as described above
will be described. When a current is applied to voice coil 1006, the current applied to voice coil
1006 and the magnetic field around voice coil 1006 cause voice coil bobbin 1005 to move up
and down with the dust cap upward in FIG. 21B. I do. By this piston movement, the diaphragm
1008 vibrates in the direction of the piston movement. As a result, sound waves are emitted from
the diaphragm 1008.
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[0017]
FIG. 22 is a diagram showing frequency characteristics regarding the reproduction sound
pressure level of the conventional speaker 1000 having a slender structure. In FIG. 22, the
vertical axis represents the reproduced sound pressure level when a power of 1 W is input to the
conventional elongated speaker 1000, and the horizontal axis represents the drive frequency.
The microphone for measuring the reproduction sound pressure level is disposed on the central
axis of the conventional elongated speaker 1000 and is located 1 m away from the conventional
elongated speaker 1000 on the front side. Do.
[0018]
The conventional elongated speaker 1000 as described above has the following problems. In the
conventional speaker 1000 having a slender structure, since a driving method of driving the
central portion of the elongated diaphragm 1008 is adopted, split resonance easily occurs in the
longitudinal direction. As a result, the frequency characteristic related to the reproduction sound
pressure level is a characteristic that causes a peak dip in the middle and high frequencies,
resulting in the deterioration of the sound quality. For example, in the characteristics shown in
FIG. 22, remarkable dips are observed around 2 kHz, 3 kHz and 5 kHz.
[0019]
Further, in order to make it difficult to cause resonance in the longitudinal direction, the
diaphragm 1008 has a deep shape (cone shape). That is, the diaphragm 1008 is shaped to have a
height in the vertical direction in FIG. 21B. Furthermore, when the diaphragm 1008 vibrates, a
distance is provided to prevent contact between the damper 1007 and the frame 1004, the
magnetic circuit such as the yoke 1003 and the plate 1002, and the damper 1007 and the
diaphragm 1008. The damper 1007 is fixed near the center of the voice coil bobbin 1005. That
is, the distance between the diaphragm 1008, the upper portion of the voice coil bobbin 1005,
the damper 1007, the lower portion of the voice coil bobbin 1005, the magnet 1001, the plate
1002 and the yoke 1003 in the vibration direction (vertical direction in FIG. 21B) It will be
provided and arranged. With the above configuration, the depth of the speaker can not be
reduced.
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[0020]
Therefore, the present inventors are difficult to cause split resonance even though they have an
elongated structure, can obtain flat frequency characteristics suppressing the occurrence of peak
dips, and can realize a thin speaker with excellent sound quality that realizes thinning. I proposed
a structure. Various aspects of the present disclosure based on this invention are as follows.
[0021]
The loudspeaker according to one aspect of the present disclosure comprises a frame, a
diaphragm having a hollow structure, and a diaphragm, which are vitrified in a hollow structure
with a frame having a longitudinal shape having a long side and a short side. And at least one
cylindrical voice coil bobbin connected through the diaphragm, the voice coil fixed to the voice
coil bobbin inside the hollow structure of the diaphragm, and the inside of the voice coil bobbin
And a magnetic circuit for driving the voice coil.
[0022]
According to this aspect, the respective components are not stacked in the direction of the
thickness of the speaker, but are arranged so as to overlap each other in a nested manner within
the hollow structure of the diaphragm, achieving thinning can do.
[0023]
As another mode, for example, the voice coil is fixed so as to arrange the voice coil bobbin at a
position dividing the height of the voice coil into two equally, and the center of gravity of the
voice coil, the fixing point of the edge to the frame, and the center of gravity of the diaphragm
And the center of gravity of the magnetic circuit are arranged on the same plane.
[0024]
According to this other aspect, it is possible to minimize the moment that the vibration system
tries to rotate and to improve the anti-rolling property.
[0025]
In another embodiment, the end of the diaphragm in the longitudinal direction is crimped by an
eyelet, a conductive wire connecting the eyelet and a terminal provided on the frame, and a lead
wire connected from the eyelet to the voice coil. And the lead wire can be fixed inside the
diaphragm.
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[0026]
According to this other aspect, it is possible to prevent disconnection of the lead wire due to
abnormal resonance or resonance vibration, and to provide an excellent speaker free of
distortion.
In addition, in order to prevent contact with the frame, it is possible to make the speaker thinner
because it is not necessary to provide an interval larger than the amplitude margin.
[0027]
In another embodiment, the magnetic circuit includes a configuration in which two magnets are
fixed in a repelling direction, or the cross-sectional shape in the short direction of the diaphragm
is circular, oval, hollow trapezoidal or It can be a hollow polygon.
[0028]
In still another aspect, for example, two voice coil bobbins may be provided, and one voice coil
bobbin may be disposed at each node position of the primary resonance mode in the longitudinal
direction of the diaphragm.
Alternatively, four voice coil bobbins may be provided, and the voice coil bobbin may be disposed
at the position of the node of the primary resonance mode and the secondary resonance mode in
the longitudinal direction of the diaphragm.
[0029]
According to this other aspect, the drive point of the diaphragm is disposed at the position at
which the first and second resonance modes are suppressed, and it is possible to realize the
expansion of the reproduction frequency band.
[0030]
Furthermore, as another aspect of the present disclosure, an auxiliary plate or an auxiliary
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magnet is used for a magnetic circuit of a speaker, a shape of both ends in a longitudinal
direction of a diaphragm is hemispherical, and a speaker is provided in an electronic device. It is
also conceivable.
[0031]
Hereinafter, embodiments will be described in detail with reference to the drawings as
appropriate.
However, more detailed description than necessary may be omitted.
For example, detailed description of already well-known matters and redundant description of
substantially the same configuration may be omitted.
This is to avoid unnecessary redundancy in the following description and to facilitate
understanding by those skilled in the art.
In addition, applicants provide the attached drawings and the following description so that those
skilled in the art can fully understand the present disclosure, and intend to limit the subject
matter described in the claims by these. Absent.
[0032]
Embodiment 1 Hereinafter, Embodiment 1 will be described.
First, the configuration of the speaker 100 in the present embodiment will be described.
FIG. 1A is a top view of the speaker 100 according to the present embodiment. FIG. 1B is a
schematic cross-sectional view taken along line A-A 'in FIG. 1A and viewed in the direction of
arrow a. FIG. 1C is a schematic cross-sectional view taken along the line B-B 'in FIG. 1A and
viewed in the direction of the arrow b.
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[0033]
The speaker 100 includes a diaphragm 110, a voice coil 120, a voice coil bobbin 130, a magnetic
circuit 140, an edge 150, a frame 160, and a dust cap 170. The speaker 100 has an elongated
shape in which the lengths in the longitudinal direction and the lateral direction are different as
shown in FIG. 1A. Hereinafter, each configuration of the speaker 100 will be described.
[0034]
First, the diaphragm 110 will be described. FIG. 2A is a plan view of the diaphragm 110, and
shows only the left side from the C-C 'line in FIG. FIG. 2B is a schematic cross-sectional view
taken along line E-E 'in FIG. 2A and viewed in the direction of arrow e. FIG. 2C is a schematic
cross-sectional view taken along line F-F 'in FIG. 2A and viewed in the direction of arrow f. As
shown in FIG. 2A, the planar shape of the diaphragm 110 viewed from the vibration direction
(the direction perpendicular to the paper surface in FIG. 2A) has a long side and a short side.
Moreover, as shown to the area | region D of FIG. 2B, the both ends of the longitudinal direction
of the diaphragm 110 have a hollow hemispherical-shaped structure. Moreover, as shown to FIG.
2C, the cross-sectional shape of the transversal direction of the diaphragm 110 is hollow circle
shape. Furthermore, as shown in FIG. 2C, the diaphragm 110 has an upper diaphragm 111a and
a lower diaphragm 111b, each of which has an elongated track provided with a bonded portion
112 at the end of the semicircular cross section in the width direction. Together. As long as the
diaphragm 110 has the cross-sectional shape as described above, it is not necessary to paste the
diaphragm 111a having the elongated track and the diaphragm 111b together as described
above. Further, as shown in FIG. 1A, the diaphragm 110 is provided with a through hole 180 for
fixing the voice coil bobbin 130. As in the present embodiment, in the case where the diaphragm
111a and the diaphragm 111b are bonded together, the through holes 180 are provided in the
diaphragm 111a and the diaphragm 111b, respectively.
[0035]
As a material of the diaphragm 110, a material suitable for thinning and light in weight is
desirable, and it is most preferable to use paper, a polymer film or the like. However, as a
material of the diaphragm 110, a lightweight high-rigidity metal foil such as aluminum or
titanium may be used.
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[0036]
Next, the voice coil 120 and the voice coil bobbin 130 will be described. FIG. 3 is a perspective
view of the voice coil 120 and the voice coil bobbin 130. The voice coil 120 is formed by winding
and fixing a thin wire made of copper or aluminum, which has been subjected to an insulation
treatment, a plurality of times onto the side surface of a cylindrical voice coil bobbin 130 having
an oval cross section. Also, the voice coil 120 is disposed at an intermediate point of the side
surface of the voice coil bobbin 130. That is, the line dividing the height of the voice coil 120
shown in FIG. 3 into two equally separates the distance α from the upper end of the voice coil
bobbin 130 and the line dividing the height of the voice coil 120 into two equal parts and the
lower end of the voice coil bobbin 130 The voice coil 120 is fixedly wound on the side surface of
the voice coil bobbin 130 so that the distance β to the part is equal.
[0037]
Next, the magnetic circuit 140 will be described. FIG. 4 is a perspective view of the magnetic
circuit 140. As shown in FIG. The size of the magnetic circuit 140 is smaller than the inner
diameter of the voice coil bobbin 130 so as to be disposed inside the voice coil bobbin 130, and
the outer diameter shape of the magnetic circuit 140 is similar to the voice coil bobbin 130.
Further, in the magnetic circuit 140, two magnetized magnets 141 are fixed in a repelling
direction, and in each of the magnets 141, a plate 142 is provided on the surface opposite to the
surface to which the magnet 141 is fixed. It is fixed. As an example of the magnetization direction
of the magnet 141 at this time, it is shown as letters N and S in FIG. The polarities of N and S are
polarities that repel each other, and are in a reversible relationship. The generated magnetic flux
horizontally travels from the joint surface 143 of the two magnets 141 and repels each other to
reach the plate 142. Further, the magnetic circuit 140 is fixed to the frame 160 by fixing the end
face of one plate 142 to the frame 160.
[0038]
Next, the edge 150 will be described. As shown in FIG. 1A, the planar shape of the edge 150 is
annular. Also, as shown in FIGS. 1B and 1C, the edge 150 has a substantially semicircular or
semi-elliptical cross section orthogonal to the vibration direction (vertical direction with the dust
cap 170 upward in FIGS. 1B and 1C). is there. The outer periphery of the diaphragm 110 is fixed
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to the inner periphery of the edge 150.
[0039]
Next, the frame 160 will be described. As shown in FIGS. 1A-C, the frame 160 is annular in shape
with an opening. As shown in FIGS. 1A-C, the outer periphery of the edge 150 is fixed to the
opening of the frame 160.
[0040]
Next, the dust cap 170 will be described. As shown in FIGS. 1B and 1C, the dust cap 170 is
provided on the upper end of the voice coil bobbin 130. The dust cap 170 passes through the
through hole 180 and blocks the sound emitted from the upper surface of the voice coil bobbin
130 in the vibration direction.
[0041]
Next, the component configuration of the speaker 100 will be described. FIG. 5 is a component
configuration perspective view of the speaker 100 according to the present embodiment.
[0042]
As shown in FIGS. 1B and 1C, the voice coil bobbin 130 is inserted into the through hole 180 of
the diaphragm 110. Further, the fixed point of the edge 150 on the frame 160, the center of
gravity of the diaphragm 110, the center of gravity of the voice coil 120, and the center of
gravity of the magnetic circuit 140 are arranged on the same plane. In the case of the present
embodiment, the diaphragm 110 is disposed on the center plane (X-X 'plane in FIG. 1B) of the
diaphragm 110 which is inside the annular cross section of the diaphragm 110 and is orthogonal
to the vibration direction.
[0043]
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12
Next, the operation and effects of the speaker 100 configured as described above will be
described. When current is applied to the voice coil 120, driving force is generated in the voice
coil 120 by the applied current and the magnetic field of the magnetic circuit 140. The generated
driving force is transmitted to the diaphragm 110 via the voice coil bobbin 130. Sound is emitted
to space by the vibration of the diaphragm 110 to which the driving force is transmitted.
[0044]
Next, with regard to the diaphragm 110 configured as described above, the effects of the case
where the cross-sectional shape in the latitudinal direction is a hollow semicircular shape and the
case of a hollow circular shape as in the present disclosure are theories and simulations. I will
explain from. First, it will be described from the viewpoint of theory.
[0045]
The diaphragm 110 can be regarded as a rod substantially free at both ends since the outer
periphery thereof is usually supported by the edge 150. Therefore, from the theory of the
vibration mode of the bar at both ends, it is possible to consider changes in the resonance
frequency of the vibration mode and the cross-sectional shape of the rigidity. Here, the theory of
the vibration mode of the bar at both ends will be described. The following formula (1) shows a
resonance frequency formula of the vibration mode of the bar at both ends.
[0046]
Here, l is the length of the rod, ρ is the density, Q is the Young's modulus of the material, and K
is the radius of gyration.
[0047]
In the above equation (1), the rotation radius K differs depending on the cross-sectional shape.
6A shows a hollow semicircular cross-sectional shape of the diaphragm 610, and FIG. 6B shows a
hollow circular cross-sectional shape of the diaphragm 110 of the present embodiment.
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[0048]
The radius of rotation for each cross-sectional shape will be described using FIGS. 6A and 6B.
First, the hollow semicircular cross-sectional shape of FIG. 6A will be described. According to the
theorem of section second moment, the section second moment of a hollow section figure such
as a pipe or a tunnel can be obtained by subtracting the section second moment of the hollow
figure from the section second moment of the outer figure Can. Although the position of the
center of the outer figure and the position of the inner figure differ with respect to the reference
axis when determining the sectional moment, in the case of a hollow semicircular cross section
such as the diaphragm 610, Because the thickness of the diaphragm 610 is very thin, the radii of
the outer and inner semicircles may be considered to be approximately equal. Therefore, the
hollow semicircular second-order cross-sectional moment is considered to be the difference
between the outer semi-circle and the inner semi-circle and the second-order geometrical
moment of each. The following equation (2) shows a non-hollow semicircular sectional second
moment, and the following equation (3) shows a hollow semicircular sectional second moment,
and the following equation (4) shows The cross-sectional area is shown.
[0049]
Here, r semi indicates the radius of a solid hollow circle.
[0050]
Here, R indicates the radius of the outer half circle, and r indicates the radius of the inner half
circle.
[0051]
[0052]
Further, since the radius of gyration is the square root of the quotient obtained by dividing the
second moment of area by the cross sectional area, the radius of gyration of the hollow
semicircular cross section is given by the following equation (5).
[0053]
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[0054]
Here, also in the case of the hollow circle, since it is possible to calculate the second moment of
area and the radius of rotation in the same way as described above, only the equation is shown
and the description is omitted.
The following formula (6) shows the second moment of area of the hollow circular cross section,
the following formula (7) shows the radius of rotation, and the following formula (8) shows its
cross sectional area.
[0055]
Here, R indicates the radius of the outer half circle, and r indicates the radius of the inner half
circle.
[0056]
[0057]
[0058]
The moment of inertia, the radius of gyration, and the cross-sectional area of each of the crosssectional shapes of the hollow circle and the hollow semicircle, calculated using the above
equations (3) to (8), are shown in FIG.
In FIG. 7, the result calculated as R = 2 mm, r = 1.8 mm, and t = 0.2 mm is shown.
[0059]
Next, using the calculated values in FIG. 7, changes in resonance frequency and changes in
rigidity due to changes in cross-sectional shape from hollow semicircle to hollow circle will be
examined.
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[0060]
From the above equation (1), it can be seen that when the length of the rod and the material
constant are the same, the change of the resonant frequency due to the change of the crosssectional shape is proportional to the radius of gyration.
Further, since the stiffness of the rod (bending stiffness) is expressed by the product of the
Young's modulus of the rod material and the second moment of area, it can be seen that the
stiffness of the rod is proportional to the second moment of area.
[0061]
Therefore, by changing the cross-sectional shape from a hollow semicircular shape to a hollow
circular shape, the rotation radius is about 1.9 times from the above expressions (5) and (7), and
the above expression (2) 6), the second moment of area is about 7.2 times, so that the resonance
frequency is about 1.9 times higher and the rigidity is about 7.2 times higher.
[0062]
Next, based on the above-described theoretical result, the resonance frequency of the natural
vibration mode by the finite element method (Finite Element Method (FEM)) incorporating the
actual shape model of the diaphragm 110 and the diaphragm 610 described in the present
embodiment. The analysis results of are shown in FIG.
In FIG. 8, the resonance frequency (theoretical value) is the result of calculation using the above
equation (1).
[0063]
In FIG. 8, the resonance mode is evaluated only when the number of nodes is an even number.
In addition, the number of nodes represents two resonances as a first mode and four cases as a
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second mode.
This is because when the number of nodes is an odd number, the resonance pressure
contributing to the sound pressure cancels out the sound pressure disturbance due to the
resonance mode on the axis, and the peak dip occurs only when the number of nodes is an even
number. It is because there is.
It can be seen from FIG. 8 that the theoretical calculation value (theoretical value) and the
simulation analysis value (FEM value) match well.
In addition, it can be seen that the resonance frequency of the diaphragm 110 having a circular
cross-sectional shape is approximately twice as high as that of the diaphragm 610 having a
semicircular cross-sectional shape.
From the change in frequency of this simulation result, the change in rigidity due to the change
in cross-sectional shape of the diaphragm from semicircular to circular is calculated back.
[0064]
From the above equation (1), the resonant frequency is proportional to the radius of gyration.
Since the radius of gyration is the square root of the quotient of the second moment of area and
the cross section, the second moment of area is proportional to the product of the square of the
radius of rotation and the cross section. Therefore, it can be understood from FIG. 8 that when
the cross-sectional shape of the diaphragm changes from semicircular to circular, the change in
the radius of rotation is approximately doubled and the cross-sectional area is also doubled, so
the rigidity is approximately 8 times .
[0065]
As described above, by setting the cross-sectional shape in the longitudinal direction of the
diaphragm to a hollow circle, the rigidity in the longitudinal direction of the diaphragm can be
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improved, and the resonant frequency of the mode can be increased. This makes it possible to
reduce the number of resonance frequencies that are affected on the important voice band.
[0066]
In the present embodiment, the cross section in the latitudinal direction of diaphragm 110 has
been described as a circular diaphragm, but by making the cross sectional shape in the latitudinal
direction of diaphragm 110 an oval, the rigidity is further enhanced. It can be raised. In addition,
the cross-sectional shape in the short direction of the diaphragm 110 may be a hollow trapezoid
or a hollow polygon.
[0067]
Next, thinning will be described. In the conventional speaker 1000 having an elongated
structure, the rigidity is enhanced by deepening the depth of the diaphragm 1008 made of cone
paper or the like. For this reason, in order to reproduce to a high frequency, a diaphragm made
of cone paper or the like with a deep depth is required, and it is difficult to realize a thin speaker.
On the other hand, the diaphragm 110 has a hollow circular cross section and increases the
second moment of area to increase the rigidity. In the diaphragm 110 having a hollow circular
cross section having the resonance frequency shown in FIG. 8, the radius of the cylinder is 2.0
mm, and the overall height of the diaphragm 110 is about 4.0 mm. In a general cone type
diaphragm such as the diaphragm 1008, in order to realize the resonance frequency 1255 Hz in
the first mode of the hollow circular diaphragm 110 shown in FIG. (Depth) is required.
[0068]
Furthermore, in the speaker 100 according to the present embodiment, further thinning is
realized in the following points.
[0069]
In the conventional elongated speaker 1000, the voice coil 1006 is connected to the end of the
diaphragm 1008 in the depth direction via the voice coil bobbin 1005.
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18
That is, the voice coil bobbin 1005 and the voice coil 1006 are arranged to be vibratably
suspended in the magnetic circuit by the edge 1010 and the damper 1007. The magnetic circuit
including the magnet 1001 and the like is disposed further to the back of the voice coil 1006
(lower part in FIG. 21B). As described above, in the conventional speaker, the thickness in which
the diaphragm 1008, the voice coil bobbin 1005, the voice coil 1006, and the magnetic circuit
including the magnet 1001 and the like are stacked is the thickness of the speaker. For example,
when the depth of the diaphragm 1008 is 20 mm, the voice coil winding width is 2.0 mm, the
amplitude margin width is 2.0 mm, and the magnetic circuit is 10 mm, the depth of the speaker
needs to be 20 + 2 + 2 + 10 = 34 mm or more.
[0070]
On the other hand, in the speaker 100 of the present embodiment, the through hole 180 is
provided in the diaphragm 110, and the voice coil 120 and the voice coil bobbin 130 are
disposed inside the diaphragm 110. Furthermore, since the magnetic circuit 140 is disposed
inside the voice coil bobbin 130, the connection surface of the diaphragm 110 is not a central
structure (X--in FIG. In the X 'plane), they are arranged so as to overlap each other in a nested
manner. Therefore, a very thin speaker can be realized as compared to the conventional speaker.
The thickness of the speaker 100 is 1⁄2 of the thickness of the voice coil bobbin 130 on the
upper side in the vibration direction and 1⁄2 of the thickness of the voice coil bobbin 130 on the
lower side of the vibration direction with the XX ′ plane in FIG. Only the amplitude margin
width (the weir shown in FIG. 1B) provided so that the voice coil bobbin 130 does not contact the
frame 160 and the thickness of the fixing surface of the frame 160 to which the magnetic circuit
140 is fixed. For example, when the amplitude margin width is 2.0 mm, the voice coil bobbin 130
can be configured to have a thickness of 7 mm and the frame thickness can be 2.0 mm, and the
thickness of the speaker 100 can be 11 mm in total.
[0071]
Subsequently, the rolling resistance characteristic will be described. Rolling is an abnormal
vibration that tries to rotate the diaphragm. By bringing the fixed point (line, surface) of the
support system as close as possible to the center of gravity of the vibration system, it is possible
to minimize and suppress the moment at which the vibration system tries to rotate.
[0072]
11-05-2019
19
The voice coil 120 of the speaker 100 is disposed inside the annular cross section of the
diaphragm 110 and on the central plane (X-X ′ plane in FIG. 1B) of the diaphragm 110
orthogonal to the vibration direction. Further, the fixed point of the edge 150 on the frame 160,
the center of gravity of the diaphragm 110 and the center of gravity of the magnetic circuit 140
are also disposed on this central plane (X-X 'plane in FIG. 1B). By this arrangement, the position
of the center of gravity of the vibration system and the position of the fixed point of the support
system are on the same plane, and a speaker excellent in anti-rolling characteristics can be
obtained.
[0073]
With the above-described configuration, the speaker 100 has an elongated structure, and by
providing characteristics in the shape of the diaphragm and the overall configuration of the
speaker, rigidity can be improved while the thickness of the entire speaker can be reduced. And
the characteristic of this whole speaker composition also produces the further effect of
suppressing abnormal vibration and improving a rolling-proof characteristic.
[0074]
Second Embodiment A loudspeaker 200 according to a second embodiment will be described
below. In addition to the speaker 100 of the first embodiment, the speaker 200 is characterized
in that a voice coil lead-out wire is fixed to the inside of the diaphragm 110.
[0075]
FIG. 9A is a top view showing the speaker 200. FIG. FIG. 9B is a schematic cross-sectional view of
FIG. 9A cut in the longitudinal direction. 9A and 9B do not display the upper diaphragm 111a of
the diaphragm 110. An eyelet 201 is crimped to the longitudinal direction end of the lower
diaphragm 111b, and is integrally formed with the lower diaphragm 111b. A conductive wire
203 is fixed to the eyelet 201, the other end of the conductive wire 203 is connected to a
terminal (not shown) provided on a frame (not shown), and a signal for driving a speaker is input.
For example, a gold wire can be used as the conductive wire 203.
11-05-2019
20
[0076]
The voice coil 120 is fixed via the voice coil bobbin 130 on the center line in the longitudinal
direction of the diaphragm 111 b. The lead wire 202 of the voice coil 120 is fixed on the inner
surface of the diaphragm 111b. The lead wire 202 is electrically connected to the conductive
wire 203 connected to the eyelet 201. The vibrating plate 111b subjected to the wiring process
is attached to the vibrating plate 111a so as to form a cylindrical shape, and the speaker 200
having the same magnetic circuit and frame configuration as that of the first embodiment is
realized.
[0077]
Next, the operation and effects of the speaker 200 configured as described above will be
described. The basic operation is the same as that of the first embodiment. The drive signal input
to the terminal of the frame 160 is provided to the other eyelet 201, the conductive wire 203
and the frame 160 through the conductive wire 203, the lead wire 202 through the one eyelet
201 and the voice coil 120 through the lead wire 202. Constitute an electrical circuit leading to
the terminal. Therefore, the voice coil 120 generates a force corresponding to the speaker input
signal to vibrate the diaphragm 110. Since the lead wire 202 is fixed to the inner surface of the
diaphragm 111b, when the diaphragm 110 is operated, it is integrated with the diaphragm 110
and vibrates. In the case of a long and thin diaphragm, disconnection may occur due to abnormal
resonance caused by the extension of the lead wire or resonance vibration. In the speaker 200,
disconnection of the lead wire 202 due to abnormal resonance or resonance vibration can be
prevented, and an excellent speaker without distortion can be provided. Furthermore, by wiring
between the elongated diaphragm 110 and the frame 160, the effect of reducing the possibility
of electrical contact with the frame 160 is also exhibited. Similarly, in order to prevent contact
with the frame 160, it is not necessary to provide an interval larger than the amplitude margin,
so the speaker can be made thinner.
[0078]
Third Embodiment The third embodiment will be described below. FIG. 10A is a top view of the
speaker 300 according to the present embodiment. FIG. 10B is a schematic cross-sectional view
taken along line G-G 'in FIG. 10A and viewed in the direction of arrow g.
11-05-2019
21
[0079]
In speaker 100 according to the first embodiment, in order to provide two voice coil bobbins
130, speaker 300 uses diaphragm 210 having two through holes 180, and via each of two
through holes 180, a voice coil bobbin 130 is fixed.
[0080]
Next, the drive position of the diaphragm will be described.
The drive position is set in consideration of the band of the speaker. In the speaker 1000
according to the conventional elongated structure and the speaker 100 according to the first
embodiment, the center of the diaphragm 1008 or 110 in the longitudinal direction is a driving
point, and one voice coil 1006 or voice coil 120 is disposed. In the case where there is no
resonance of the diaphragm 1008 or 110 within the operating frequency band, that is, in the
case where the low range is mainly reproduced, the above-mentioned structure may be
employed. In this case, the diaphragm is piston-oscillated to the first resonance frequency.
[0081]
However, in order to further flatten the sound pressure frequency characteristics, it is necessary
to suppress the generated resonance mode. Therefore, the speaker 300 is provided with two
driving points (voice coils) in order to suppress the first resonance mode generated first and to
realize flat characteristics until the second resonance mode generated next. . The driving point
for controlling the first resonance mode may be provided at the node position of the first
resonance mode. When the rigidity of the diaphragm 210 is higher than that of the edge 150 and
the mass of the edge 150 is as light as that of the diaphragm 210, the resonance mode of the
diaphragm 210 is substantially the same as the resonance mode of the bar at both ends.
Therefore, assuming that the longitudinal direction length of the diaphragm 210 is 1, the
positions of the nodes of the primary resonance mode in the longitudinal direction of the
diaphragm 210 are 0.224 and 0.776 from the longitudinal end of the diaphragm 210. It
becomes a corresponding position. That is, the voice coil bobbin 130 is located at a node position
of the primary resonance mode in the longitudinal direction of the diaphragm 210, ie, from the
longitudinal direction end of the diaphragm 110 when the longitudinal length of the diaphragm
110 is 1. It is preferable to fix at a position corresponding to .224 and 0.776. If the first
resonance mode is suppressed, the band will be expanded to about four times its frequency. In
the case of FIG. 8, the first resonance mode is suppressed, and the frequency can be expanded to
11-05-2019
22
the frequency of the next second resonance mode. Therefore, according to the present
embodiment, the reproduction frequency can be made higher than in the first embodiment.
[0082]
In addition, the speaker 300 according to the present embodiment does not affect the thickness
of the speaker in order to realize expansion of the reproduction frequency band with the number
of driving points.
[0083]
Fourth Embodiment The fourth embodiment will be described below.
FIG. 11A is a top view of the speaker 400 according to the present embodiment. 11B is a
schematic cross-sectional view taken along line H-H 'in FIG. 11A and viewed in the direction of
arrow h.
[0084]
In speaker 300 according to the third embodiment, in order to further provide two voice coil
bobbins 130, speaker 400 uses diaphragm 310 having four through holes 180, and voices are
transmitted through each of four through holes 180. The coil bobbin 130 is fixed.
[0085]
As in the speaker 400, if the number of driving points is four and the driving points are arranged
at positions suppressing both the first and second resonance modes, the band is further
expanded.
Assuming that the longitudinal direction length of the diaphragm 110 is 1, under the same
assumption as the first resonance mode, x1 = 0.1130, x2 = 0.37775, x3 = (1-x2) = 0.62225, x4
The voice coil bobbin 130 may be fixed at a position corresponding to = (1−x1) = 0.8870. As
described above, when the number of driving points is four, the reproduction band is extremely
wide, and it is possible to configure a speaker that performs piston movement without generation
of resonance.
11-05-2019
23
[0086]
Here, FIG. 12A shows sound pressure frequency characteristics when the node position of the
first resonance mode is driven (two-point drive). Further, FIG. 12B shows sound pressure
frequency characteristics when four voice coils are at positions where both of the first and
second resonance modes are suppressed (four-point drive). Further, FIG. 12C shows sound
pressure frequency characteristics in the case of center drive. When FIG. 12A, FIG. 12B, and FIG.
12C are compared, it is understood that the resonance mode is suppressed and the reproduction
frequency band is expanded by devising the number and position of the driving points.
[0087]
Further, as with the speaker 300 according to the third embodiment, the speaker 400 according
to the present embodiment realizes expansion of the reproduction frequency band with the
number of driving points, and therefore does not affect the thickness of the speaker.
[0088]
Fifth Embodiment A loudspeaker 500 according to a fifth embodiment will be described below.
FIG. 13 is a perspective view showing a magnetic circuit 540 used for the speaker 500. As shown
in FIG. FIG. 14 is a cross-sectional view of the speaker 500 in the lateral direction.
[0089]
The magnetic circuit 540 has a structure in which an auxiliary plate 401 is further disposed on
the magnetic circuit 140 according to the first embodiment. The auxiliary plate 401 wraps
around on both sides of the joint surface 143 of the magnet 141. The auxiliary plate 401 adheres
to the end face of one plate 142 and is disposed on the outside of the diaphragm 110 so as to
wrap around on both sides of the joint surface 143 of the magnet 141. Also, as an example of the
magnetizing direction of the magnet 141 at this time, it is shown as letters N and S in FIG. The
polarities of N and S are polarities that repel each other, and are in a reversible relationship.
11-05-2019
24
[0090]
Next, the operation and effects of the speaker 500 configured as described above will be
described. In FIG. 14, the flow of magnetic flux is indicated by a broken arrow. The generated
magnetic flux, after coming out in the horizontal direction from the joint surface 143 of one of
the magnets 141, reaches the plate 142 while mutually repelling the magnetic flux from the
other magnet 141. At this time, in the speaker 500, the auxiliary plate 401 constitutes a
magnetic circuit. After the magnetic flux generated from the magnet 141 horizontally emerges
from the joint surface 143, it reaches the auxiliary plate 401. The magnetic flux then travels
inside the auxiliary plate 401 and reaches the plate 142. For this reason, the magnetic flux of the
component perpendicular to the direction of the current flowing through the coil wire linked to
the voice coil 120 is increased.
[0091]
Further, as in the first embodiment, when current is applied to the voice coil 120, driving force is
generated in the voice coil 120 by the applied current and the magnetic field of the magnetic
circuit. The generated driving force is transmitted to the diaphragm 110 via the voice coil bobbin
130. Sound is emitted to space by vibrating the diaphragm 110 to which the driving force is
transmitted.
[0092]
As described above, in the speaker 500, since the magnetic flux linked to the voice coil 120
increases, it is possible to realize a speaker capable of reproducing a large sound with a higher
sound pressure. That is, by utilizing the structure in which the magnetic circuit is embedded in
the diaphragm well and arranging the auxiliary plate 401, the magnetic flux can be increased
without expanding the space, and the sound pressure can be improved.
[0093]
Sixth Embodiment A loudspeaker 600 according to a sixth embodiment will be described below.
FIG. 15 is a perspective view showing a magnetic circuit 640 used for the speaker 600. As shown
11-05-2019
25
in FIG. FIG. 16 is a cross-sectional view of the speaker 600 in the short direction. FIG. 17 is a
schematic view showing the component configuration of the speaker 600. As shown in FIG.
[0094]
The magnetic circuit 640 has a structure in which auxiliary magnets 601 are further disposed on
both sides of the joint surface 143 of the magnet 141 in the magnetic circuit 140 according to
the first embodiment.
[0095]
The auxiliary magnet 601 is fixed to the side of the joint surface 143 at a position separated
from the diaphragm 110 by the frame 160.
The magnetizing direction of the auxiliary magnet 601 is the direction orthogonal to the magnet
141. When the joint surface 143 is magnetized to the N pole, the S pole is magnetized in the
direction of the joint surface 143, and the joint surface is When 143 is a south pole, it is
magnetized so that the north pole is in the direction of the junction surface 143. As one example
of the magnetizing directions of the magnet 141 and the auxiliary magnet 601, they are shown
as letters N and S in FIG. The polarities of N and S are polarities that repel each other, and are in
a reversible relationship.
[0096]
Next, the operation and effects of the speaker 600 configured as described above will be
described. In FIG. 16, the flow of magnetic flux is indicated by a broken arrow. After the magnetic
flux generated in the horizontal direction from the joint surface 143 of the magnet 141, the
magnetic flux generated from the auxiliary magnet 601 is added, and they repel each other and
reach the plate 142. For this reason, the magnetic flux of the component perpendicular to the
direction of the current flowing through the coil wire linked to the voice coil 120 is increased.
[0097]
Further, as in the first embodiment, when current is applied to the voice coil 120, driving force is
11-05-2019
26
generated in the voice coil 120 by the applied current and the magnetic field of the magnetic
circuit. The generated driving force is transmitted to the diaphragm 110 via the voice coil bobbin
130. Sound is emitted to space by the vibration of the diaphragm 110 to which the driving force
is transmitted.
[0098]
As described above, in the speaker 600, the magnetic flux linked to the voice coil 120 is
increased, so that a speaker capable of reproducing a large sound with a higher sound pressure
can be realized. That is, by utilizing the structure in which the magnetic circuit is embedded in
the diaphragm well and arranging the auxiliary magnet 601, the magnetic flux can be increased
without expanding the space, and the sound pressure can be improved. Further, as in the fourth
embodiment, the auxiliary plate 401 may be provided, and the auxiliary magnet 601 may be
provided on the auxiliary plate 401. As a result, the magnetic flux can be further increased and
the sound pressure can be improved without expanding the space.
[0099]
Other Embodiments Further, Embodiments 1 to 6 have been described as examples of
implementation in the present disclosure. However, the present disclosure is not limited to this,
and is also applicable to an embodiment in which changes, replacements, additions, omissions,
and the like are appropriately made. In addition, since the speakers described in the first to sixth
embodiments can be easily thinned, they can be used for flat-screen TVs, electronic devices such
as mobile phones, PDAs, and the like. That is, the electronic device can be configured to include
the speaker according to the present disclosure and a housing that holds the speaker inside.
Therefore, other embodiments will be exemplified below.
[0100]
FIG. 18 shows a mobile information terminal device 701 equipped with a speaker selected from
among those shown in the first to sixth embodiments of the present disclosure. In FIG. 18, 702 is
a screen, and 700 is a speaker selected from those shown in the first to sixth embodiments. In
FIG. 18, the speakers 700 are arranged at three locations, but any number of speakers may be
used as long as it has one or more speakers. If there is only one speaker device, it will be
monaural, but if it is two stereo or two or more, it can also be used as a device for sound field
11-05-2019
27
control and HRTF. By mounting the speaker 700 in a device having a limited mounting volume
such as the mobile information terminal device 701, broadband reproduction can be stably
performed even in a limited volume. With respect to the mounting direction when mounting the
speaker 700, the diaphragm may be directed to the sound hole side with respect to the sound
hole provided in the housing, or the frame may be directed to the sound hole side.
[0101]
Further, FIG. 19 shows an image display device 801 equipped with a speaker selected from
among those shown in the first to sixth embodiments of the present disclosure. More specifically,
the image display device 801 is a PC, a thin TV, or the like. In FIG. 19, reference numeral 202
denotes a screen, and 800 denotes a speaker selected from those shown in the first to sixth
embodiments. In FIG. 19, the speaker 800 is disposed at a total of 16 locations, but any number
of speakers 800 may be used as long as it is one or more. If it is one, it will be monaural, but if it
is two, it can be used as a device for sound field control or HRTF (for example, if it is arranged as
a line array) if two or more can be used. By mounting the speaker 800 in an apparatus such as
the image display device 801 having a limited mounting volume, broadband reproduction can be
stably performed even in a limited volume. With respect to the mounting direction when
mounting the speaker 800, the diaphragm may be directed to the sound hole side with respect to
the sound hole provided in the housing, or the frame may be directed to the sound hole side.
[0102]
Further, FIG. 20 shows a mounting view of the on-vehicle speaker. In FIG. 20, 901 is a door of a
car, and 900 is a speaker selected from those shown in the first to sixth embodiments of the
present disclosure. In FIG. 20, the loudspeakers 900 are arranged at three locations, but any
number of loudspeakers 900 may be used as long as they are one or more. Although FIG. 20
shows an example attached to the door 901 of an automobile, it may be attached to any position
of the automobile such as a dashboard, a pillar, a seat, a headrest, and a ceiling of the automobile.
Moreover, you may attach to various moving means, such as a train, a monorail, a linear motor,
an airplane, and a ship, besides a motor vehicle. Heretofore, large-sized speakers have been
required for wide-band reproduction, particularly for low-pitched reproduction. The loudspeakers
shown in the first to sixth embodiments of the present disclosure can realize a thinner
loudspeaker than conventional loudspeakers. As a result, the entire moving means can be
downsized, and the comfort can be improved by increasing the living space. With regard to the
mounting direction at the time of mounting, the diaphragm may be directed to the sound hole
side with respect to the sound hole provided in the housing, or the frame may be directed to the
11-05-2019
28
sound hole side.
[0103]
The speaker according to the present disclosure can be used for flat-screen TVs, electronic
devices such as mobile phones and PDAs.
[0104]
100, 200, 300, 400, 500, 600, 700, 800, 900 Speaker 110, 111a, 111b, 210, 310, 610
Diaphragm 112 Bonding portion 120 Voice coil 130 Voice coil bobbin 140, 540, 640 Magnetic
circuit 141 Magnet 142 Plate 143 bonding surface 150 edge 160 frame 170 dust cap 180
through hole 202 lead wire 203 conductive wire 401 auxiliary plate 601 auxiliary magnet 701
mobile information terminal device 702 screen 801 image display device 901 door of automobile
11-05-2019
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