Optical waveguides – With disengagable mechanical connector
Reexamination Certificate
1999-05-07
2001-04-17
Font, Frank G. (Department: 2877)
Optical waveguides
With disengagable mechanical connector
C385S134000
Reexamination Certificate
active
06217227
ABSTRACT:
The present invention relates to a connection device for optical fiber cables.
BACKGROUND OF THE INVENTION
Connection devices for optical fiber cables are used in particular for making up buried long distance lines where cable segments of determined length are united end-to-end.
Each connection device is housed in a sealed protective box which is generally filled with a gas under pressure to prevent dust penetrating into the box.
One of the difficulties encountered in designing such connection devices lies in organizing the various optical fibers of each cable, since each fiber needs to be connected individually to a fiber of another cable.
A connection device for optical fiber cables is already known in which the fibers are connected together in pairs by means of a splice and each pair of fibers made in this way is coiled and then housed in a cassette, thereby preventing the pairs of fibers from tangling with one another.
More precisely, in that known device, the optical fibers are connected together in pairs by means of individual splices which are grouped together side by side in one or more cassettes.
The reserve lengths of fiber which are necessary for making splices are then coiled and secured in the cassette(s) in the immediate vicinity of the splices, firstly to prevent them from tangling with one another, and secondly to keep control over their radius of curvature.
In that prior device, each fiber must be of determined length before the splicing operation so that in the final position of the splice in the cassette, the fiber loops can be positioned and secured in ordered manner. That constitutes a first difficulty in implementing the device.
In addition, in order to repair a splice or to interchange two splices, it is necessary to gain access to the inside of the or each cassette concerned, to release the fiber loops, and to change the lengths thereof as a function of the new organization for the splices after action has been taken. Those operations are thus particularly lengthy and difficult.
OBJECTS AND SUMMARY OF THE INVENTION
The present invention seeks to solve those drawbacks by proposing a novel connection device for optical fiber cables, which connection device comprises:
a longitudinal support having a substantially plane top face extending longitudinally and two convex side flanks extending longitudinally on either side of said top face and going towards the underside of said top face, the radius of curvature of the cross-section of each flank being not less than the minimum radius of curvature of the optical fibers of the cables to be connected;
a plurality of individual connection elements for connecting optical fibers in pairs, each connection element extending transversely over the top face of the longitudinal support; and
an empty space left beneath the longitudinal support and defined in part by the support, the optical fibers penetrating into the connection device via said empty space and coiling freely therein prior to going directly to an individual connection element fixed on the top face of the longitudinal support by being held against one of the flanks of said longitudinal support.
In the connection device of the invention, the stripped optical fibers are subjected to a minimum amount of stress since they are held at their two ends only, i.e. on entry into the device where they penetrate into the empty space, and on the flanks of the longitudinal support immediately before reaching the individual connection elements.
Over the remainder of their length, the stripped optical fibers are left free to position themselves naturally in the empty space.
The connection device of the invention is preferably housed in a box having inlets for cables at both ends, said inlets opening out beneath the longitudinal support into the empty space.
Because of the empty space, all of the optical fibers coming from a single cable can have the same length whatever the particular individual connection element on which each fiber terminates.
In a preferred embodiment of the invention, the longitudinal support is mounted on a central leg about which the optical fibers can coil. This leg enables the longitudinal support to rotate relative to the box.
Thus, the connection device can be operated on by raising the longitudinal support slightly and causing it to turn through 90° relative to the box, the loops formed by the optical fibers in the space provided for this purpose constituting reserve lengths of fiber that make such rotation possible.
It will be understood that the connection device of the invention makes it easy to modify a connection by displacing the end of one optical fiber from one individual connection element to another, or to interchange the ends of two optical fibers, without any difficulty.
Similarly, if the end of an optical fiber has been damaged, the fiber can be shortened so as to prepare its end again merely by pulling lightly on the fiber, and the only consequence of so doing is to tighten the loop formed by the optical fiber beneath the longitudinal support.
In addition, because of the simple way in which optical fiber lengths are stored in the empty space, the device of the invention makes it possible to minimize the handling required for installing the fibers.
In this respect, the device of the invention is much more practical to implement than are conventional connection devices in which, as is generally recommended, the reserve lengths of optical fiber are coiled in cassettes and secured at a plurality of locations so that they follow an imposed path.
In a particular embodiment of the invention, the longitudinal support is of substantially oval cross-section.
In another embodiment, said longitudinal support is provided with guides on its flanks on either side of its top face carrying the connection elements, each guide leading a fiber radially from the bottom edge of the flank to the end of an individual connection element.
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Font Frank G.
Nguyen Sang Hoang
Oliff & Berridg,e PLC
Proptic
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