Information
-
Patent Grant
-
6671952
-
Patent Number
6,671,952
-
Date Filed
Monday, February 25, 200222 years ago
-
Date Issued
Tuesday, January 6, 200420 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Tugbang; A. Dexter
- Nguyen; Tai
Agents
-
CPC
-
US Classifications
Field of Search
US
- 029 868
- 029 830
- 029 832
- 029 840
- 029 842
- 029 843
- 029 854
- 029 860
- 029 861
- 029 859
- 029 DIG 48
- 219 5621
- 219 5622
- 219 92
- 219 110
-
International Classifications
-
Abstract
A method of lead wire connection includes mounting a lead wire onto an uppre surface of a land portion, supplying a cover member onto the lead wire, pressing the lead wire via the cover member against the upper surface of the land portion by a first electrode tool, heating the first electrode tool to expose a part of the lead wire, and applying an electric current between the first electrode and a second electrode tool so that resistance welding is effected between the cover member and the lead wire and between the lead wire and the land portion.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a structure and a method for connecting a coated lead wire with a land portion, and a clad material adapted for lead wire connection.
2. Description of the Related Art
In JP-A-9-84191, a process of removing an insulating coating of a conductor wire is carried out independently of a process of connecting the wire with an electrically conductive adhesive agent. In JP-A-9-84192, a process of removing an insulating coating of a conductor wire is carried out independently of soldering. In JP-A-9-200895, a land portion to which a coil terminal is to be connected has a substantially circular shape to prevent occurrence of a defect in connection due to a solder splitting phenomenon.
In soldering connection, the improvements as described above are needed to prevent occurrence of a defect in connection. As a result, the shape of the land portion is restricted. Especially, a coil terminal connectable region is limited in a very small component such as an electroacoustic transducer. Accordingly, the restriction of the shape of the land portion results in that the degree of freedom in product design is limited.
As a recent measure against environmental problems, it is desired that elements which may have a possibility to give a bad influence to an environment are refrained from being used to the utmost in production of electronic components, circuit boards, electronic equipment, and the like. Especially, soldering is a popular method for electrically connecting conductors. If electronic equipment is illegally dumped, lead contained in solder might be eluted and adversely affect the environment.
It is considered to use lead free soldering as a measure against the environment problems. However, such a lead-free soldering has a higher melting point in temperature than any one of the methods in the conventional art. Accordingly, the component material must be high in heat-resistance and the producing cost thereof increases.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a structure and a method of lead wire connection in which electric connection can be performed surely between conductors without using any solder, and to provide a clad material adapted for lead wire connection.
According to an aspect of the present invention, there is provided a structure of lead wire connection comprising:
a lead wire covered with an electrical insulating coating;
a land portion electrically connected to the lead wire; and
a cover member disposed in opposition to the land portion with the lead wire held between the land portion and the cover member;
wherein the cover member and the lead wire are electrically connected by resistance welding; and
the lead wire and the land portion are also electrically connected by resistance welding.
According to the present invention, since resistance welding is carried out in a condition that the cover member is disposed on the lead wire, an electrode tool for resistance welding does not come into direct contact with the lead wire. Accordingly, it is possible to prevent damage or disconnection of the lead wire from occurring. Even if the lead wire is extra fine, electrical connection can be carried out surely.
Further, since the cover member is interposed between the lead wire and the electrode tool, the pressing force of the electrode tool can be set to a high value so that the contact area between the cover member and the lead wire and the contact area between the lead wire and the land portion increase. As a result, the welding area becomes large and reduction in the connection resistance can be attained.
Further, conductors can be electrically connected surely to each other without using any solder. Accordingly, a bad influence on the environment due to the elements composing the solder can be eliminated.
Further, a liquid binder such as solder becomes unnecessary. Accordingly, regardless the shape of the land portion, no defect in connection due to a solder splitting phenomenon is generated. As a result, the degree of freedom in design of shape of the land portion is improved greatly.
Further, according to the present invention, there is provided a method of lead wire connection comprising:
mounting a lead wire covered with an electrical insulating coating onto an upper surface of a land portion;
supplying a cover member onto the lead wire;
pressing the lead wire via the cover member against the upper surface of the land portion by a first electrode tool having a heater mechanism while supporting a lower surface of the land portion by a second electrode tool;
heating the first electrode tool by the heater mechanism to make the lead wire exposed partially; and
applying an electric current between the first and second electrode tools so that resistance welding is effected between the cover member and the lead wire and between the lead wire and the land portion.
According to the present invention, if the heater mechanism is operated in a condition that the cover member, the lead wire, and the land portion are held between the first and second electrode tools, the coating of the lead wire is partially removed by heat to thereby make the lead wire exposed. In this condition, the electric contact of the first electrode tool with the cover member, the lead wire, and land portion is attained. Next, when an current is applied between the first and second electrode tools, much Joule heat is generated in a contact portion where the electric resistance is high so that the cover member and the lead wire are subjected to resistance welding, and the lead wire and the land portion are also subjected to resistance welding.
Since resistance welding is performed in a condition that the cover member is disposed on the lead wire, the electrode tool for resistance welding does not come into direct contact with the lead wire so that the lead wire can be prevented from being damaged or disconnected. Accordingly, even if the lead wire is extra fine, it is possible to realize the electric connection surely.
Further, since the cover member is interposed between the lead wire and the electrode tool, the pressing force of the electrode tool can be set to a high value so that the contact area between the cover member and the lead wire and the contact area between the lead wire and the land portion increase. As a result, the welding area becomes large and reduction in the connection resistance can be attained.
Further, conductors can be electrically connected surely to each other without using any solder. Accordingly, a bad influence on the environment due to the elements composing the solder can be eliminated. Further, a defect in connection due to a solder splitting phenomenon can be eliminated so that the degree of freedom in design of shape of the land portion is improved greatly.
Further, according to the present invention, there is provided a method of lead wire connection comprising:
mounting a lead wire covered with an electrical insulating coating onto an upper surface of a land portion;
supplying a cover member onto the lead wire;
pressing the lead wire via the cover member against the upper surface of the land portion by a pressure welding tool having a heater mechanism; and
heating the pressure welding tool by the heater mechanism to make the lead wire exposed partially, and to supply a melted portion of the cover member around the lead wire and the land portion.
According to the present invention, when the heater mechanism is operated in a condition that the cover member, the lead wire, and the land portion are pressed by the pressure welding tool, the coating of the lead wire is partially removed by heat to thereby make the lead wire exposed. In this condition, as the temperature of the pressure welding tool becomes high, the cover member is partially melted and the melted material is supplied to the connection portion between the lead wire and the land portion.
Since thermal welding is performed in a condition that the cover member is disposed on the lead wire, the pressure welding tool does not come into direct contact with the lead wire so that the lead wire can be prevented from being damaged or disconnected. Accordingly, even if the lead wire is extra fine, it is possible to realize the electric connection surely.
Further, since the cover member is interposed between the lead wire and the pressure welding tool, the pressing force of the pressure welding tool can be set to a high value so that the contact area between the cover member and the lead wire and the contact area between the lead wire and the land portion increase. As a result, the welding area becomes large and reduction in the connection resistance can be attained.
Further, conductors can be electrically connected surely to each other without using any solder. Accordingly, a bad influence on the environment due to the elements composing the solder can be eliminated. Further, a defect in connection due to a solder splitting phenomenon can be eliminated so that the degree of freedom in design of shape of the land portion is improved greatly.
Further, according to a still further aspect of the present invention, the cover member includes a laminate of a plurality of metal materials having different melting points in which the metal material brought into contact with the lead wire has a melting point lower than a melting point of the metal material brought into contact with the pressure welding tool.
According to the present invention, since a material of a high melting point is disposed on the pressure welding tool side and a material of a low melting point is disposed on the lead wire side, the low melting point material is melted first upon welding and supplied to the connection portion between the lead wire and the land portion. Therefore, the melted material of the cover member plays roles of reinforcing the connection strength, reducing the connection resistance, performing oxidation protection, and so on. On the other hand, since the high melting point material is not melted, separation of the cover member from the pressure welding tool is easy so that the pressure welding tool can be prevented from contamination.
Further, according to the present invention, there is provided a clad material for lead wire connection comprising:
a laminate of a plurality of metal materials having different melting points,
wherein the clad material is disposed between a lead wire and a welding tool when the lead wire and a land portion are connected by resistance welding or thermal welding.
According to the present invention, when a clad material constituted by a laminate of a high melting point material disposed on the welding tool side and a low melting point material disposed on the lead wire side is used as the cover member, the low melting point material is melted first upon resistance welding or thermal welding and supplied to the connection portion between the lead wire and the land portion. Therefore, the clad material plays roles of reinforcing the connection strength, reducing the connection resistance, performing oxidation protection, and so on. On the other hand, since the high melting point material is not melted, separation of the cover member from the welding tool is easy so that the welding tool can be prevented from contamination.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1A
is an exploded perspective view and
FIG. 1B
is a sectional side view, both showing an example of an electronic component to which the present invention is applicable.
FIGS. 2A
to
2
D show an example of a method of lead wire connection according to the present invention.
FIG. 2A
being a perspective view,
FIG. 2B
being a front view,
FIG. 2C
being an exploded sectional view of cover members
52
a
,
FIG. 2D
being an exploded sectional view of a welded portion.
FIGS. 3A and 3B
show another example of the method of lead wire connection according to the present invention,
FIG. 3A
being a front view,
FIG. 3B
being an exploded sectional view of a connection portion.
FIG. 4
is a front view showing a further example of the method of lead wire connection according to the present invention.
DETAILED DESCRIPTION OF THE PRESENT INVENTION
The present invention will be described with reference to the accompanying drawings.
FIGS. 1A and 1B
show an example of an electronic component to which the present invention is applicable.
FIG. 1A
is an exploded perspective view and
FIG. 1B
is a sectional side view.
An electroacoustic transducer
1
includes a base
24
, a magnetic core
22
, a coil
23
, a magnet
25
, a support ring
26
, a diaphragm
20
, a lower housing
30
and an upper housing
10
. The base
24
, the magnetic core
22
, the coil
23
, the magnet
25
, the supporting ring
26
and the diaphragm
20
are received on the lower housing
30
and covered with the upper housing
10
so that the electroacoustic transducer
1
is formed to have a rectangular plane shape as a whole. The total size thereof is, for example, about 10 mm wide×12 mm long×2 mm high.
The lower housing
30
is made of synthetic resin such as thermoplastic resin or the like, and includes a plurality of protrusions
31
formed around a circumference of the base
24
. The base
24
is formed in a disc shape partially notched to have an approximately D shape, and mounted inside of the protrusions
31
on the lowering housing
30
. The magnetic core
22
has a columnar shape, and is erected in the center of the base
24
so that the coil
23
is wound around the magnetic core
22
. The base
24
and the magnetic core
22
are made of magnetic materials. Alternatively, the base
24
and the magnetic core
22
may be integrally formed as a single pole piece member by press fitting or the like.
The magnet
25
has an annular shape having an inner diameter smaller than that formed by the protrusions
31
. The magnet
25
is disposed on the base
24
so as to be concentric with the magnetic core
22
. Accordingly, the annular inner space is ensured between the magnet
25
and the coil
23
.
The support ring
26
is made of a non-magnetic material, and has an outer diameter slightly smaller than the inner diameter formed by the protrusions
31
so that the support ring
26
is disposed in contact with the base
24
. A plurality of annular steps are formed in the inner side of the support ring
26
. Among these steps, a protrusion
27
has a back side to abut against the upper and outer surfaces of the magnet
25
to regulate the position of the magnet
25
. Further, a supporting step
28
is formed annularly on above the protrusion
27
, so that the diaphragm
20
is mounted on the step
28
. Accordingly, the diaphragm
20
is positioned in place.
The diaphragm
20
is made of a magnetic material. The diaphragm
20
is supported by the step
28
of the support ring
26
in the circumferential edge so that a predetermined space is ensured between the back center of the diaphragm
20
and the top end of the magnetic core
22
. A disc magnetic piece
21
is fixed to the front center of the diaphragm
20
so that the mass of the diaphragm
20
is increased to thereby improve the oscillation efficiency of air.
The upper housing
10
is made of synthetic resin such as thermoplastic resin or the like. The upper housing
10
is shaped such as a box to be matched with the shape of the lower housing
30
. The upper housing
10
and the lower housing
30
are bonded to each other with an adhesive agent, by ultrasonic welding, and so on.
A sound-emitting hole
11
is formed in the ceiling center of the upper housing
10
. Protrusions
15
are formed on the inner side of the upper housing
10
to abut against the upper surface of the support ring
26
. The protrusions
15
regulate the position of the support ring
26
, as shown in FIG.
1
B.
In state where the upper housing
10
is mounted, protrusions
14
formed on the ceiling surface of the upper housing
10
are positioned at regular intervals from the magnetic piece
21
of the diaphragm
20
. The protrusions
14
prevent the diaphragm
20
from dropping-out or being deformed when a strong shock is given to the transducer. The protrusions
14
have a low height enough not to impede the normal oscillation of the diaphragm
20
.
Two plate electrically conductive members are incorporated in the lower housing
30
by insert molding or the like. An end of each of these electrically conductive members is exposed on the corner portion of the upper surface of the lower housing
30
to form a connection land
50
a
(
50
b
). The other end is exposed on opposite side surfaces of the lower housing
30
, which forms a circuit board connecting terminal
51
.
A lead wire
23
a
(
23
b
) of the coil
23
passes through the notched portion of the base
24
and is led out to the connection land
50
a
(
50
b
). The lead wire
23
a
(
23
b
) is disposed on the connection land
50
a
(
50
b
). A cover member
52
a
(
52
b
) is disposed on the lead wire
23
a
(
23
b
). The lead wire
23
a
(
23
b
) is held between the cover member
52
a
(
52
b
) and the connection land
50
a
(
50
b
).
The cover member
52
a
(
52
b
) is electrically connected with the lead wire
23
a
(
23
b
) by resistance welding or thermal welding. The lead wire
23
a
(
23
b
) is electrically connected with the connection land
50
a
(
50
b
) by resistance welding or thermal welding.
An opening
33
is formed in a position corresponding to the connection land
50
a
(
50
b
) of the lower housing
30
. The opening
33
exposes the lower surface of the connection land
50
a
(
50
b
) to the outside so as to facilitate accessibility to the connection land
50
a
(
50
b
) by a tool, when the lead wire
23
a
(
23
b
) and the connection land
50
a
(
50
b
) are connected to each other electrically.
Operation will be described below. Referring to
FIG. 1B
, the magnet
25
is magnetized in the thickness direction. For example, suppose that the bottom surface of the magnet
25
is magnetized to an N pole while the top surface of the magnet
25
is magnetized to an S pole. The lines of magnetic force coming from the bottom surface of the magnet
25
sequentially pass the circumferential edge portion of the base
24
, the center portion of the base
24
, the magnetic core
22
, the center portion of the diaphragm
20
, the circumferential edge of the diaphragm
20
and the top surface of the magnet
25
. Accordingly, one closed magnetic circuit is formed as a whole. The magnet
25
supplies a static magnetic field to the magnetic circuit to stably support the diaphragm
20
when the diaphragm
20
is attracted toward the side of the magnetic core
22
and the magnet
25
.
The coil
23
supplies the oscillation magnetic field to the magnetic circuit, when the coil
23
wound around the magnetic core
22
is supplied with an electric oscillation signal via the terminals
51
and the lead wires
23
a
and
23
b
from the circuit board. Then, the diaphragm
20
oscillates due to superimposition between the static magnetic field and the oscillation magnetic field. Eventually, air on the top surface side of the diaphragm
20
and air on the bottom surface of the diaphragm
20
oscillate.
The front space Va of the diaphragm
20
forms a resonance chamber. Sound at a high sound pressure level is produced when the oscillation frequency of the diaphragm
20
is substantially coincident with the resonance frequency of the resonance chamber. Then, the sound is emitted to the outside from the sound-emitting hole
11
of the upper housing
10
. Sound produced on the back side of the diaphragm
20
is confined in the annular inner space because the sound on the back side is an antiphase against the sound on the front side. Hence, interference of the sound on the back side with the sound on the front side can be suppressed as much as possible.
FIGS. 2A
to
2
D show an example of a method of lead wire connection according to the present invention.
FIG. 2A
is a perspective view,
FIG. 2B
is a front view,
FIG. 2C
is an exploded sectional view of cover members
52
a
,
FIG. 2D
is an exploded sectional view of a welded portion.
An upper electrode tool
61
is provided with a built-in heater
62
, and supported vertically movable in opposition to a lower electrode tool
63
. The heater
62
is supplied with heater electric power from a power source
71
. A switch
72
turns operation of the heater
62
on/off. Welding electric power is supplied between the electrode tools
61
and
63
from a power source
73
. A switch
74
turns the welding operation on/off.
First, the lead wire
23
a
covered with an electrical insulating coating is mounted on the upper surface of the connection land
50
a
. Next, the cover member
52
a
is supplied onto the lead wire
23
a
, and then, the electrode tool
61
is moved down. In such a condition, the lead wire
23
a
is pressed by the electrode tool
61
via the cover member
52
a
against the upper surface of the connection land
50
a
while the lower surface of the connection land
50
a
is supported by the electrode tool
63
.
Each of the cover members
52
a
is made of a metal material such as Zn (zinc), Sn (tin) or Ni (nickel). Although the cover members
52
a
may be supplied one by one, the cover members
52
a
may be supplied in the form of a tape of an elongated plate material in which the cover members
52
a
are partially rapped by half-blanking press (push-back), as shown in
FIG. 2C
, so that manufacturability can be improved.
Next, a switch
72
is closed so that an electric current flows into the heater
62
to heat the electrode tool
61
. Thus, the coating of the lead wire
23
a
is broken to thereby make the conductor portion exposed partially.
Next, when the switch
74
is closed so that an electric current is passed between the electrode tool
61
and the electrode tool
63
, much Joule heat is generated in the contact portion where electrical resistance is high so that the cover member
52
a
and the lead wire
23
a
are resistance-welded while the lead wire
23
a
and the connection land
50
a
are also resistance-welded. Accordingly, nuggets Q of fused materials are formed, as shown in FIG.
2
D. Finally, the switches
72
and
74
are opened and the electrode tool
61
is moved up.
Thus, the conductors can be electrically connected to each other surely without using any solder. The connection process for the lead wire
23
b
and the connection land
50
b
can be also performed in accordance with the above description.
FIGS. 3A and 3B
show another example of the method of lead wire connection according to the present invention.
FIG. 3A
is a front view, and
FIG. 3B
is an exploded sectional view of the connection portion.
A pressure welding tool
64
provided with the built-in heater
62
is disposed so as to be vertically movable in opposition to a lower support
65
. The heater
62
is supplied with a heater electric power from a power source
71
, the operation of the heater
62
being turned on/off by a switch
72
.
First, the lead wire
23
a
covered with an electrical insulating coating is mounted on the upper surface of the connection land
50
a
. Next, a cover member
80
is supplied onto the lead wire
23
a
, and then, the pressure welding tool
64
is moved down. In such a condition, the lead wire
23
a
is pressed by the pressure welding tool
64
via the cover member
80
against the upper surface of the connection lead
50
a
while the lower surface of the connection land
50
a
is supported by the support
1
65
.
The cover member
80
is constituted by a laminate of a plurality of metal materials
81
and
82
which are different from each other in melting point. The high melting point material
81
is formed of a metal material such as Ni (nickel, melting point: 1,400° C.) or the like. The low melting point material
82
is formed of a metal material such as Sn (tin, melting point: 630° C.) or the like so that the melting point of the low melting point material
82
is set to be lower than the melting point (700° C.-800° C.) of Cu or phosphor bronze forming the lead wire
23
a
or the connection land
50
a
. As the cover member
80
, a clad material constituted by a laminate of a plurality of metal materials may be used, so that the cover members
80
may be provided, for example, in the form of a tape from a roll to thereby improve the manufacturability.
Further, when the high melting point material
81
is disposed on the pressure welding tool
64
side, the cover member
80
is easily separated from the pressure welding tool
64
so that the pressure welding tool
64
can be prevented from contamination.
Next, the switch
72
is closed so that an electric current flows into the heater
62
to heat the pressure welding tool
64
. Thus, the coating of the lead wire
23
a
is broken to thereby make the conductor portion exposed partially.
Further, when the current capacity of the heater
62
is increased and the temperature of the pressure welding tool
64
is raised, the low melting point material
82
located on the lead wire side of the cover material
80
is partially melted, and supplied to the connection portion between the lead wire
23
a
and the connection land
50
a
, as shown in FIG.
3
B. Accordingly, the low melting point material
82
functions as reinforcing the connection strength, reducing the connection resistance, performing oxidation protection, and so on. Finally, the switch
72
is opened so that the pressure welding tool
64
is moved up.
In such a manner, the conductors can be electrically connected to each other surely without using any solder. The connection process for the lead wire
23
b
and the connection land
50
b
can be also performed in accordance with the above description.
FIG. 4
is a front view showing a further example of the method of lead wire connection according to the present invention. Here, the cover member
80
is supplied in the form that a high melting point material
81
and a low melting point material
82
are prepared in separate rolls and laminated on each other in the stage of the connection process.
As described above in detail, according to the present invention, when the cover member is disposed on the lead wire, the tool does not come into direct contact with the lead wire so that damage or disconnection of the lead wire can be prevented.
Further, with interposition of the cover member, the pressing force of the tool can be set to a high value so that the contact area is enlarged and reduction in the connection resistance can be attained.
Further, conductors can be electrically connected to each other surely without using any solder so that a bad influence on the environment due to the elements composing the solder can be eliminated.
Further, a defect in connection due to the solder splitting phenomenon can be eliminated so that the degree of freedom in design of the shape of the land portion is improved greatly.
Claims
- 1. A method of lead wire connection comprising:mounting a lead wire covered with an electrical insulating coating onto an upper surface of a land portion; supplying a cover member onto the lead wire, the cover member made of a metal material and separately formed from the lead wire and the land portion; pressing the lead wire via the cover member against the upper surface of the land portion by a first electrode tool having a heater mechanism while supporting a lower surface of the land portion by a second electrode tool; heating the first electrode tool by the heater mechanism to make the lead wire exposed partially; and applying an electric current between the first and second electrode tools so that resistance welding is effected between the cover member and the lead wire and between the lead wire and the land portion, simultaneously.
- 2. A method of lead wire connection comprising:mounting a lead wire covered with an electrical insulating coating onto an upper surface of a land portion; supplying a cover member onto the lead wire, the cover member formed separately from the lead wire and the land portion; pressing the lead wire via the cover member against the upper surface of the land portion by a pressure welding tool having a heater mechanism; heating the pressure welding tool by the heater mechanism at a first temperature to make the lead wire exposed partially; and heating the pressure welding tool by the heater mechanism at a second temperature higher than the first temperature to supply a melted portion of the cover member around the lead wire and the land portion.
- 3. The method of lead wire connection according to claim 2, wherein the cover member comprises a laminate of a plurality of metal materials having different melting points; andthe metal material brought into contact with the lead wire has a melting point lower than a melting point of the metal material brought into contact with the pressure welding tool.
- 4. A method of lead wire connection comprising:mounting a lead wire covered with an electrical insulating coating onto an upper surface of a land portion; heating the electrical insulating coating at a first temperature by a pressure welding tool having a heater mechanism to melt the electrical insulating coating on the upper surface of the land portion; supplying a cover member onto the lead wire on the upper surface of the land portion, the cover member formed separately from the lead wire and the land portion; and heating a portion of the cover member by the heater mechanism at a second temperature higher than the first temperature and lower than the melting point of the land portion to melt the portion to supply the melted portion around the lead wire and the land portion.
- 5. A method of lead wire connection comprising:mounting a lead wire covered with an electrical insulating coating onto an upper surface of a land portion; supplying a cover member onto the lead wire on the upper surface of the land portion, the cover member formed separately from the lead wire and the land portion; pressing the lead wire via the cover member against the upper surface of the land portion by a pressure welding tool having a heater mechanism; bringing a non-melting portion of the cover member in contact with the pressure welding tool; supplying a melting portion of the cover member onto the lead wire on the upper surface of the land portion; and heating a portion of the cover member by the heater mechanism at a predetermined temperature to melt and supply the melting portion around the lead wire and the land portion.
Priority Claims (1)
Number |
Date |
Country |
Kind |
P. 2001-055107 |
Feb 2001 |
JP |
|
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Kawagoe et al. |
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A |
5800663 |
Imahori et al. |
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A |
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A |
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