Optical waveguides – Miscellaneous
Reexamination Certificate
2002-03-26
2003-06-10
Zarroli, Michael C. (Department: 2839)
Optical waveguides
Miscellaneous
C030S090100, C083S947000, C225S096000
Reexamination Certificate
active
06577804
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a sheathed optical fiber cutting method and apparatus.
BACKGROUND ART
There are sheathed optical fibers that are drawn from an optical fiber mother material and have a sheath on an optical fiber (bare fiber bearing no coat on its outer surface) made of a core and a clad. It is necessary to cut such a sheathed optical fiber as follows in one step in order to efficiently and accurately measure the decentering of the sheath and mode fields such as the refractive index distribution. Namely, a sheathed optical fiber needs cutting so that no step is left between the sheath and the optical fiber as well as its sheared edge is perpendicular to the axial direction.
The prior art cutting apparatus for sheathed optical fibers meeting the above needs holds the sheathed optical fiber
1
having an optical fiber
1
a
and a sheath
1
b
with right and left clamps
2
and
3
, as shown in
FIG. 15
, for example. A cutting blade
4
that slides between the clamps
2
and
3
is pushed onto the sheathed optical fiber
1
to make an incision in the fiber. Afterward, a block
5
facing the cutting blade
4
pushes the sheathed optical fiber
1
to cut the sheathed optical fiber
1
.
In this type of cutting apparatuses, the cutting blade
4
may cut the sheathed optical fiber
1
, with the sheathed optical fiber
1
being held by the right and left clamps
2
and
3
and provided with tension in its longitudinal direction. In other cases, after the right and left clamps
2
and
3
have clamped the sheathed optical fiber
1
, either clamp moves away from the other, and then the sheathed optical fiber
1
is cut, being provided with tension.
Meanwhile, there are proposed cutting apparatuses like those shown in
FIGS. 16A and 16B
that can cut a sheathed optical fiber without leaving a step between its sheath and optical fiber to provide a flat sheared edge perpendicular to the axial direction.
Such cutting apparatuses hold the sheath
1
b
at the end of the sheathed optical fiber
1
with the clamp
3
and the optical fiber
1
a
from which the sheath
1
b
has been removed with the clamp
2
, respectively. The optical fiber
1
a
is cut by the cutting blade
4
between the clamps
2
and
3
. The clamp
3
fixing the sheath
1
b
has an elastic body
6
such as a spring that repels to the opposite direction to the cutting blade
4
to provide the sheathed optical fiber
1
with constant tension.
These cutting apparatuses further have, between the clamp
3
and the cutting blade
4
, tension providing means
9
having a slope
7
and an index plunger
8
. The slope
7
is formed on the clamp
3
so that it gradually increases the tension applied to the sheathed optical fiber
1
after an incision is made on the sheathed optical fiber
1
by sliding the cutting blade
4
until the sheathed optical fiber is cut. The index plunger
8
is mounted on the side of the cutting blade
4
and its end is pushed against the slope
7
.
However, in the cutting apparatus shown in
FIG. 15
, a compressive stress is applied to the sheath because the edge of the cutting blade
4
digs into the incision made in the sheath of the sheathed optical fiber
1
during the cutting of the sheathed optical fiber
1
. As a result, the sheath is likely to collapse when employing this type of cutting apparatuses, and the edge of the cutting blade
4
often slips off the sheath because of the elasticity of the sheath. Besides, because the cutting blade
4
digs into the sheathed optical fiber
1
from a single direction, the sheath is torn during cut and the cutting of the optical fiber inside the sheath is affected.
Therefore, using the cutting apparatus shown in
FIG. 15
, it is difficult to cut the sheathed optical fiber
1
, leaving no step between the sheath and the optical fiber, and to provide a flat sheared edge perpendicular to the axial direction.
Meanwhile, the cutting apparatuses shown in
FIGS. 16A and 16B
remove the sheath
1
b
of the sheathed optical fiber
1
and then cut only the optical fiber
1
a
. Those cutting apparatuses thus need a preliminary process for removing the sheath
1
b
prior to cutting, requiring two steps for cutting the sheathed optical fiber
1
.
An object of the present invention is to provide a sheathed optical fiber cutting method and apparatus that can cut sheathed optical fibers, leaving no step between the sheath and the optical fiber, and provide a flat sheared edge perpendicular to the axial direction in a single step.
DISCLOSURE OF THE INVENTION
In order to solve the above problems, a sheathed optical fiber cutting method based on a first aspect of the present invention is constituted in such a manner that an incision is made by a cutting blade, under such a condition that the sheathed optical fiber is relatively rotated around its center axis against the cutting blade and bent, in an area having a bent curvature larger than that of the center of the bent optical fiber along the center axis, from the tension-applied surface to which a tension is applied due to fiber bending toward the fiber center, and the sheathed optical fiber is cut.
In the sheathed optical fiber cutting method based on the first aspect, the sheathed optical fiber cutting method based on a second aspect of the present invention is constituted in such a manner that the sheath of the sheathed optical fiber is sheared and then the optical fiber where a cutout has been made is cut.
Further in the sheathed optical fiber cutting method based on the first aspect, the sheathed optical fiber cutting method based on a third aspect of the present invention is constituted in such a manner that the cutting blade makes the incision in the tension-applied surface under such a condition that the sheathed optical fiber is pulled along its axial direction.
A sheathed optical fiber cutting apparatus based on a fourth aspect of the present invention comprises: a clamp part that holds the sheathed optical fiber; a cutting blade that makes an incision toward the center of the sheathed optical fiber; a blade block that is located against the cutting blade beyond the sheathed optical fiber and supports the sheathed optical fiber where an incision is to be made by the cutting blade; tension providing means for forming in the sheathed optical fiber a tension-applied surface to which a tension due to fiber bending is applied by pushing and bending the blade block onto the sheathed optical fiber and having a mechanism of relatively pushing the tension-applied surface onto the cutting blade; and rotating means for relatively rotating the sheathed optical fiber around its center axis against the cutting blade.
The sheathed optical fiber cutting apparatus based on a fifth aspect of the invention is the sheathed optical fiber cutting apparatus based on the fourth aspect of the invention, wherein the tension providing means further has a tension providing mechanism for providing additional tension to the tension-applied surface of the sheathed optical fiber by pulling the sheathed optical fiber to its axial direction in order to gradually increase the tension applied to the sheathed optical fiber as the incision made by the cutting blade becomes deeper.
The sheathed optical fiber cutting apparatus based on a sixth aspect of the invention is the sheathed optical fiber cutting apparatus based on the fourth or fifth aspect of the invention, wherein the cutting blade is mounted in vibration generating means for vibrating in a radial direction of the sheathed optical fiber.
The sheathed optical fiber cutting apparatus based on a seventh aspect of the invention is the sheathed optical fiber cutting apparatus based on the fourth, fifth or sixth aspect of the invention, wherein; the cutting blade comprises a first cutting blade for cutting the sheath of the sheathed optical fiber and a second cutting blade for cutting the optical fiber, and the first and second cutting blades are mounted in a cutting blade exchange guide so that they may shuttle between an operation position for cutting the sheath of t
Jie Xu
Mikami Toshihiro
Murakami Akihiro
Yamazaki Takanobu
Knobbe Martens Olson & Bear LLP
The Furukawa Electric Co. Ltd.
Zarroli Michael C.
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