Optical waveguides – With disengagable mechanical connector
Reexamination Certificate
2002-03-27
2003-07-08
Abrams, Neil (Department: 2839)
Optical waveguides
With disengagable mechanical connector
C385S060000, C385S072000
Reexamination Certificate
active
06588937
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical coupling device for separating and assembling optical signals by using a branched type optical fiber arranged in a case, and more particularly to an optical coupling device for easing optical stress working on the optical fiber.
2. Description of the Prior Art
FIG. 7
shows a plan of an example of optical coupling device according to the prior art.
In the optical coupling device according to the prior art shown in
FIG. 7
, a plurality of optical fibers are bundled on one end side, and mounted as an internal fiber.
The internal fiber is formed by bundling a plurality of optical fibers on one end side in a state in which the diameters of individual optical fibers are made gradually thinner to equalize the diameters of their end faces to those of an optical fiber to be connected thereto. When optical signals are transmitted from a first end face side of the bundled end of the optical fiber, it is possible at a second end side of the branched optical fibers to separate the optical signals and to let each fiber receive the same optical signals. Or when optical signals are transmitted from at the second end side of the branched optical fibers, it is possible on the first bundled end side to assemble and receive the optical signals.
An optical coupling device
1
shown in
FIG. 7
is intended for connection of a plug
11
for use with an F05 type single-core optical fiber connector conforming to Japanese Industrial Standards (JIS)-C-5974 and a plug
12
for use with an F07 type two-core optical fiber connector conforming to JIS-C-5976. In the case
2
of the optical coupling device
1
, there are provided a bundled end
3
a
formed by bundling one end (end on the X
1
side in the drawing) of each of two optical fibers and a 1-to-2 branched internal fiber
3
formed by integrating branched ends
3
b
and
3
b
formed by branching the other ends of the fibers.
At the one bundled end
3
a
of the internal fiber
3
is provided a ferrule (holding member)
4
, and at the branched ends
3
b
are provided ferrules (holding member)
5
. The ends of the internal fiber
3
are firmly fixed to the ferrules
4
and
5
with an adhesive. The tips of the bundled end
3
a
and the branched end
3
b
are fitted in a state in which they barely protrude out of the case
2
from the tips of the ferrules
4
and
5
, respectively, and these protruding portions constitute stubs
3
a
1
and
3
b
1
.
The case
2
is made of synthetic resin. On one end face of the case
2
in the X direction in the drawing is formed a connecting part (connector)
2
A, protruding in the X
1
direction in the drawing, for connecting the F05 type plug
11
, and on the end face is formed a connecting part
2
B, protruding in the X
2
direction in the drawing, for connecting the F07 type plug
12
. To the ends of the connecting parts
2
A and
2
B of the case are fitted caps
6
and
7
. In the caps
6
and
7
are formed through holes
6
a
,
7
a
and
7
a
, respectively.
Tubular sleeve holders
2
a
,
2
b
and
2
b
are formed in the X
1
-X
2
direction in the drawing integrally with the connecting parts
2
A and
2
B, respectively. Between the inward ends of these sleeve holders
2
a
and
2
b
and the caps
6
and
7
are respectively provided the ferrules
4
and
5
, respectively, fitted to ends of the internal fiber
3
.
On the outer faces of the ferrules
4
and
5
are formed flanges
4
a
and
5
a
extending the direction of the external circumference. Between the flanges
4
a
and
5
a
on the one hand and the caps
6
and
7
on the other are respectively provided cylindrical coil springs
8
,
9
and
9
. Therefore, the ferrules
4
and
5
are held within the case
2
in a state in which the inward ends of the sleeve holder
2
a
and the sleeve holders
2
b
are pressed in the outward direction by the coil springs
8
and
9
. The tips of the ferrules
4
and
5
are set on an optical reference plane S—S represented by a one-dot chain line in the drawing, and the stubs
3
a
1
and
3
b
1
protrude outward from the optical reference plane S—S.
In the optical coupling device
1
, when the F05 type plug
11
is connected to one connecting part
2
A, an end face
11
a
of an optical fiber
11
A of the F05 type plug
11
presses an end face of the bundled end
3
a
in the optical coupling device
1
in a direction toward inside the case
2
, with the result that the coil spring
8
is compressed, and the end face of the stub
3
a
1
is returned to the optical reference plane S—S. When the F07 type plug
12
is connected to the other connecting part
2
B, end faces
12
a
and
12
a
of one optical fiber
12
A of the F07 type plug
12
press end faces of the branched ends
3
b
and
3
b
. Therefore, the coil springs
9
and
9
are compressed in the direction of X
1
in the drawing, end faces of the stubs
3
b
1
and
3
b
1
are returned to the optical reference plane S—S.
Thus, when the plug
11
and the plug
12
are fitted, the end face
11
a
of the optical fiber
11
A of the plug
11
presses the end face of the bundled end
3
a
inward (in the X
2
direction), and the end faces
12
a
and
12
a
of the optical fibers
12
A and
12
A of the plug
12
press the end faces of the branched end
3
b
and
3
b
of the internal fiber
3
inward (in the X
1
direction). This brings both end faces of the optical fibers
11
A,
12
A and
12
A and the end faces of the internal fiber
3
into tight contact with each other to reduce coupling losses of optical energy between the end faces.
However, the conventional optical coupling device
1
described above involves the problem that the connection of the plug
11
for use with the F05 type and of the plug
12
for use with the F07 type causes compressive stresses to work inward on the internal fiber
3
within the case
2
from both ends of the internal fiber
3
, and as a result excessive stresses tend to concentrate on the branching portion
3
A of the internal fiber
3
.
Regarding this problem, the compressive stresses working on the internal fiber
3
can be reduced, and the concentration of stress on the branching portion
3
A eased, by increasing the overall length of the internal fiber
3
.
However, a greater overall length of the internal fiber
3
means a correspondingly greater overall length of the case
2
, which makes it impossible to reduce the size of the optical coupling device
1
.
SUMMARY OF THE INVENTION
The present invention, attempted to solve the above-noted problems with the prior art, is to provide an optical coupling device permitting alleviation of compressive stresses which would otherwise tend to concentrate on the branching portion of the internal fiber.
Another object of the invention is to provide an optical coupling device permitting a reduction in the overall length of the internal fiber and accordingly in the overall size of the device.
According to the present invention, there is provided an optical coupling device provided in its case with an internal fiber, holding members for holding each of two ends of the internal fiber, first and second connectors each holding one or the other of the holding members shiftably in an axial direction of the internal fiber, and energizing means each energizing, within one or the other connector, the holding member toward a connecting part of the connector, wherein each of the connecting parts of the first and second connectors permits fitting of a plug for holding an external fiber, each connector has within the case a margin of shifting at least toward outside the case, the plug is fitted to the connecting part of the first connector, and the second connector can shift toward outside the case when the first connector is at a limit of inward shifting and a holding member pressed by the plug shifts inward in the case.
Further, when a plug is fitted to the connecting part of the second connector, the second connector reaches a position of shifting limit inward in the case and, when the holding member in the second
Imai Seisaku
Katoh Masashi
Oka Mikio
Abrams Neil
ALPS Electric Co. Ltd.
Beyer Weaver & Thomas LLP
Hyeon Hae Moon
LandOfFree
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