Optical waveguides – Accessories – External retainer/clamp
Reexamination Certificate
2001-07-10
2003-12-23
Lee, John D. (Department: 2874)
Optical waveguides
Accessories
External retainer/clamp
C385S096000, C385S097000, C385S134000
Reexamination Certificate
active
06668128
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a fusion-splicing method for splicing optical fibers, a cleaving apparatus for cleaving the tip of optical fibers, a fusion-splicing apparatus for splicing optical fibers which have been cleaved at the tip thereof, and an optical fiber holder.
As a method for splicing optical fibers, a fusion-splicing method has been practiced. This fusion-splicing method consists of the following three steps. The first step involves stripping the coating from the tip of the optical fiber using a stripping apparatus called stripper (remover). The second step comprises cleaving the optical fiber thus exposed to a predetermined length using an optical fiber cleaving apparatus. The third step comprises fusion-splicing the optical fibers with the tip thereof abutted to each other using a fusion-splicing apparatus.
In the fusion-splicing step, electric discharge starts while the tip of the optical fibers are kept at a predetermined distance and positioned at the fusion starting position. Subsequently, one or both of the optical fibers are pushed in a direction such that the distance between the tip thereof is reduced. Thereafter, the tip of the optical fibers are spliced at the fusion end position to complete fusion-splice. There are two methods for positioning the tip of optical fibers to each other. The first method comprises positioning the coated portion of the optical fiber in the vicinity of the tip thereof with the optical fiber exposed at the tip thereof using a V-groove. The second method comprises positioning the exposed optical fiber itself using a V-groove. In any of these methods, positioning of the tip of the optical fiber must be conducted precisely.
FIG. 9
is a diagram illustrating a structure for supporting an optical fiber in a conventional fusion-splicing apparatus. In
FIG. 9
, only a mechanism for supporting one of the two optical fibers is shown. In
FIG. 9
, the reference numeral
1
indicates a coated optical fiber, the reference numeral
1
a
indicates an optical fiber, the reference numeral
31
indicates an optical fiber holding table, the reference numerals
32
a
,
32
b
each indicate a clamping member, the reference numeral
33
indicates a slider mechanism, and the reference numeral
34
indicates a supporting table.
The optical fiber holding table
31
is provided with a groove (not shown) in which the optical fiber
1
having a protective coating is received. The optical fiber
1
received in the groove is clamped by the clamping members
32
a
,
32
b.
The optical fiber holding table
31
is supported on the supporting table
34
via the slider mechanism
33
in such an arrangement that it can move along the axis of the optical fiber
1
thus clamped. The supporting table
34
and the other supporting table (not shown) are disposed opposed to each other and are supported on the respective optical fiber holding table
31
. These supporting tables are arranged such that they can be moved by the respective movement mechanism (not shown) to align the tip of the optical fiber
1
a
obtained by exposing the optical fiber
1
.
Referring to the operation of this fusion-splicing apparatus, an optical fiber is set in a stripper. The optical fiber is then stripped at the tip thereof. Subsequently, the optical fiber is set in a cleaving apparatus. The optical fiber is then cleaved at the tip thereof. Thereafter, the optical fiber is set in the optical fiber holding table
31
of the fusion-splicing apparatus described in connection with
FIG. 9
where it is then subjected to fusion-splice. However, the length (cleaved length) of the optical fiber thus cleaved is not constant itself. Since this fusion-splicing apparatus employs a procedure requiring the removal of the optical fiber from the cleaving apparatus and the transfer of the optical fiber to the optical fiber holding table
31
, the position in the longitudinal direction of the optical fiber
1
clamped by the clamping members
32
a
,
32
b
is not constant. As a result, it takes much time to align the tip of the optical fiber. Further, since the optical fiber
1
is clamped at the tip thereof by the clamping member
32
a
, the coating may be curved if it is not sufficiently clamped. As a result, the position of the tip of the optical fiber
1
a
cannot be stably fixed with a good precision.
FIG. 10
illustrates an embodiment of the holder mechanism for fusion-splicing apparatus designed to improve the precision of fixing of an optical fiber. Like numerals are used for like parts in
FIGS. 9 and 10
. The description of parts similar to those of
FIG. 9
will be omitted. In
FIG. 10
, the reference numerals
34
a
,
34
b
each indicate a supporting table, the reference numeral
35
indicates a V-groove member, and the reference numeral
36
indicates a clamping member.
As shown in
FIG. 10
, the V-groove member
35
and the clamping member
36
are provided besides the optical fiber holding table
31
for holding the optical fiber
1
and the clamping member
32
a
. The coated optical fiber
1
is clamped by the V-groove member
35
and the clamping member
36
at the position close to the tip thereof. In this arrangement, the clamping force applied to the coated optical fiber
1
at the position close to the tip thereof can be enhanced, making it possible to improve the precision of fixing of the optical fiber
1
a
. The V-groove member
35
is supported on the supporting table
34
b
. Another supporting table (not shown) is disposed opposed to the supporting table
34
b
. The optical fiber
1
clamped in the respective V-groove member
35
is then stripped at the tip thereof. These supporting tables are arranged such that they can be moved using the respective movement mechanism (not shown) to align the tip of the optical fiber
1
a
thus exposed.
In the fusion-splicing apparatus comprising the foregoing holder mechanism, when the optical fiber
1
a
is pushed by the slider mechanism
33
during fusion, the optical fiber holding table
31
moves forward. However, since the V-groove member
35
does not move, the optical fiber
1
makes sliding movement forward against the clamping force by the V-groove member
35
and the clamping member
36
. Accordingly, when the clamping force is large, the optical fiber
1
can undergo buckling or cannot move through the V-groove, making it impossible to perform good splice. On the contrary, when the clamping force is small, the optical fiber
1
cannot be stably clamped.
FIG. 11
is a schematic diagram illustrating a holder mechanism described in Japanese Patent Unexamined Publication No. Hei. 9-113752. FIG.
11
(A) is a schematic diagram. FIG.
11
(B) is a sectional view of the fitting portion. Like numerals are used for like parts in
FIGS. 9
,
10
and
11
. The description of parts similar to those of
FIG. 9
will be omitted. In
FIG. 11
, the reference numeral
37
indicates a holder, the reference numeral
37
a
indicates a tapered pin, the reference numeral
38
indicates a holder mount, and the reference numeral
38
a
indicates a tapered hole.
Referring to the operation of this holder mechanism, the optical fiber
1
which has been stripped at the tip thereof is clamped in the holder
37
. The holder
37
is prepared for each of the optical fiber
1
to be spliced. The holder
37
comprises the tapered pin
37
a
provided at the bottom thereof. At the holder mounting portion of the cleaving apparatus for cleaving the optical fiber
1
a
of the optical fiber
1
is provided a tapered hole in which the tapered pin
37
a
is fitted. In this arrangement, the holder
37
is positioned in the cleaving apparatus using the tapered pin
37
a
and the tapered hole. Accordingly, the cleaving position of the optical fiber is constant with respect to the holder
37
.
In order to splice optical fibers to each other, the holder having the optical fiber
1
clamped therein is removed from the cleaving apparatus, and then mounted on the holder mount
38
of the fusion-splicing apparatus as shown in FIG.
11
(A). The holder mo
Hattori Kazunari
Ito Yutaka
Watanabe Tsutomu
Lee John D.
Lin Tina M
Sumitomo Electric Industries Ltd.
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