GB2151042A

GB2151042A - Optical fibre jointing

Info

Publication number: GB2151042A
Application number: GB08430921A
Authority: GB
Inventors: David Turner Parr; Ian Peter Doyle
Original assignee: BICC PLC
Current assignee: Balfour Beatty PLC
Priority date: 1983-12-07
Filing date: 1984-12-07
Publication date: 1985-07-10
Also published as: GB2151042B; GB8430921D0; GB8332696D0

Abstract

Apparatus for effecting controlled introduction of a pair of optical fibres into opposite ends of an interstice in an optical fibre joint assembly to effect an optical fibre butt joint comprises three upstanding supports 5, 15 arranged along a rectilinear axis. The intermediate support 5 is fixed in space and supports a joint assembly in groove 7, and the outer supports 15 are adapted to support the optical fibres in grooves 17 in axial alignment with the interstice in the joint assembly. The ends of the optical fibres are positioned equal distances from central support 5 by retractable positioning means 36 and the outer supports then moved in unison (eg by means of threaded shaft 25) towards the central support to cause the fibres to enter into opposite ends of the joint assembly. <IMAGE>

Description

SPECIFICATION Optical fibre jointing This invention relates to jointing of optical fibres, one or each of which may be an element of an optical cable.

In one kind of end-to-end butt joint between optical fibres, a joint assembly is employed comprising at least two elongate members which are held together side by side by a surrounding sleeve and which define between them an elongate space extending throughout the length of the assembly in which two optical fibres introduced into opposite ends of the elongate space can be held in axial alignment with their neighbouring end faces abutting or spaced a short distance apart.

joint assemblies of this kind will hereinafter, for convenience, be referred to as "of the kind described".

In effecting an end-to-end optical fibre butt joint using a joint assembly of the kind described, care must be taken to ensure that an end of an optical fibre is not damaged to an unacceptable extent as the end of the optical fibre is introduced into the elongate space of the joint assembly. The care necessary to ensure that no such damage is effected to an end of an optical fibre means that the time taken to effect the optical fibre butt joint can be of undesirable length.

It is an object of the present invention to provide improved apparatus for effecting controlled introduction of a pair of optical fibres into opposite ends of an elongate space in a joint assembly of the kind described by means of which risk of unacceptable damage to an end of an optical fibre is substantially reduced and an end-to-end optical fibre butt joint can be simply and rapidly effected.

According to the invention, the improved apparatus comprises three upstanding supports arranged along a rectilinear axis each of which supports has, at its upper end, a substantially horizontal surface along which a groove extends in a direction substantially parallel to said rectilinear axis, the grooves in the surfaces of the three supports being in alignment and the intermediate support being fixed in space and equally spaced from the outer supports which are so coupled together that they are constrained to move in unison towards or away from the intermediate support in said rectilinear direction; means for effecting said movement of the outer supports; means associated with the intermediate support for clamping a joint assembly of the kind described in the groove in the surface of the intermediate support and means associated with each outer support for clamping an optical fibre in the groove in the surface of the outer support, the depths of the grooves in the surfaces of the three supports being such that an elongate space in a joint assembly clamped in the groove of the intermediate support and optical fibres clamped in the grooves in the surfaces of the outer supports will be in substantially axial alignment; and, retractable between the intermediate support and each outer support, transversely extending means for initially positioning the leading ends of optical fibres to be clamped in the grooves in the surfaces of the outer supports substantially equal distances from the central transverse axis of the groove in the surface of the intermediate support, the arrangement being such that, after a joint assembly has been clamped in the groove of the intermediate support and optical fibres, with their leading ends abutting said transversely extending positioning means, have been clamped in the grooves of the outer supports, said transversely extending positioning means is withdrawn and the outer supports are moved in unison towards the intermediate support to cause the optical fibres carried by the outer supports to be introduced into opposite ends of said elongate space in the joint assembly.

Preferably, the surfaces of the intermediate and outer supports have two or more than two sets of aligned grooves, each set of aligned grooves extending substantially parallel to the direction of motion of the outer supports so that the apparatus can be employed to effect simultaneously two or more than two optical fibre butt joints.

In a preferred embodiment, the means for effecting movement, in unison, of the outer supports in a direction towards or away from the intermediate support comprises a shaft which, over a part of its length, is in screw threaded engagement with one of the outer supports and which, over another part of its length, is in screw threaded engagement with the other outer support, the screw thread over one part of the shaft being of opposite hand to the screw thread over the other part of the shaft and the outer supports being restrained against rotational movement with respect to the shaft so that, by appropriate rotation of the shaft, the outer supports can be moved, in unison, towards or away from the intermediate support.

The transversely extending means for positioning leading ends of optical fibres supported in the grooves of the outer supports at equal distances from the central transverse axis of the groove in the surface of the intermediate support may take any convenient form but preferably comprises a pair of arms each of which is pivotally or slidably mounted on the intermediate support between the intermediate support and one of the outer supports and each of which preferably has remote from the intermediate support, a substantially flat surface lying in a plane substantially normal to the common axis of the grooves in the surfaces of the supports. Where the pair of arms are pivotally mounted on opposite faces of the intermediate support, preferably the end of each arm remote from the pivotal axis is integral with or connected to the end of the other arm.

The means for clamping a joint assembly of the kind described in the groove in the surface of the intermediate support and the means for clamping an optical fibre in the groove in the surface of each outer support each preferably comprises a transversely extending elongate member which, at one of its ends, is pivotally mounted on the support and which, at the other of its ends, has an aperture through which a clamping screw can be screwed into a tapped hole in the surface of the support but, of course, any other convenient clamping means can be employed.

The invention is further illustrated by a description, by way of example, of preferred apparatus for effecting controlled introduction of a pair of optical fibres into opposite ends of the elongate space in a joint assembly of the kind described with reference to the accompanying drawing which shows a perspective view of the preferred apparatus.

Referring to the drawing, the apparatus comprises an elongate base 1 having, at each of its ends, upstanding end walls 2 and having intermediate of its width and extending throughout its length a channel 3. At a position mid-way between the end walls 2, is a fixed intermediate support 5 which has, at its upper end, a substantially horizontal surface 6 along which extends a groove 7 of approximately V-shaped cross-section. Pivotally mounted on-the intermediate support 5 is a transversely extending elongate member 8 which, by means of a clamping screw (not shown) passing through an aperture at one end of the member into a tapped hole 9 in the surface of the support, can be employed to clamp a joint assembly of the kind described in the groove 7.

Between the fixed intermediate support 5 and each end wall 2, is an upstanding outer support 1 5 which is keyed in the channel 3 in the elongate base 1 and which has, at its upper end, a horizontal surface 1 6 along which is a groove 1 7 of substantially Vshaped transverse cross-section in alignment with the groove 7 in the surface of the intermediate support 5. Pivotally mounted on each outer support 1 5 is a transversely extending elongate member 18 which, by means of a clamping screw 1 9 passing through an aperture at one end of the member into a tapped hole 20 in the surface 16 of the outer support, can be used to clamp an optical fibre in the groove 17.

Extending between the end walls 2 and through apertures in the intermediate support 5 and outer supports 1 5 is a shaft 25 which, over a part of its length, is in screw threaded engagement with one outer support 1 5 and which, over another part of its length, is in screw threaded engagement with the other outer support 15, the screw thread in engagement with one outer support being of opposite hand to the screw thread in engagement with the other outer support and the outer supports being so positioned on the shaft that they are equally spaced from the intermediate support.

Rotation of the shaft 25 by means of the knob 26 at one end of the shaft in one direction will cause the outer supports 1 5 to slide, in unison, in a direction towards the intermediate support 5 and rotation of the shaft in the opposite direction will cause the outer supports to slide in a direction away from the intermediate support.

Pivotally mounted on the fixed intermediate support 5, is a substantially U-shaped bracket 35 whose limbs 36 have substantially flat surfaces which lie in planes substantially normal to the-common axis of the grooves 7 and 1 7 and which constitute surfaces of transverselSrtretractable means by means of which the leading ends of optical fibres supported in grooves 1 7 in the surfaces 16 of outer supports 1 5 can be positioned at equal distances from the central transverse axis of the groove 7 in the surface 6 of the intermediate support 5 prior to clamping of the optical fibres in the grooves 1 7.

After a joint assembly of the kind described has been clamped in the groove 7 of the intermediate support 5 by means of the elongate member 8 and optical fibres (not shown), with their leading ends abutting the flat surfaces of the limbs 36 of the bracket 35, have been clamped in the grooves 1 7 of the outer supports 15, the bracket 35 is so pivoted that it is no longer between the optical fibres and the joint assembly and, by appropriate rotation of the knob 26, the outer supports are caused to slide, in unison, in the direction towards the intermediate support 5 to cause the optical fibres carried by the outer supports to be introduced into opposite ends of the etongate space in the joint assembly carried by the intermediate support 5.

Claims

1. Apparatus for effecting controlled introduction of a pair of optical fibres into opposite ends of an elongate space in a joint assembly of the kind described, which apparatus comprises three upstanding supports arranged along a rectilinear axis each of which supports has, at its upper end, a substantially horizontal surface along which a groove extends in a direction substantially parallel to said rectilinear axis, the grooves in the surfaces of the three supports being in alignment and the intermediate support being fixed in space and equally spaced from the outer supports which are so coupled together that they are constrained to move in unison towards or away from the intermediate support in said rectilinear direction; means for effecting said move ment of the outer supports: means associated with the intermediate support for clamping a joint assembly of the kind described in the groove in the surface of the intermediate support and means associated with each outer support for clamping an optical fibre in the groove in the surface of the outer support, the depths of the grooves in the surfaces of the three supports being such that an elongate space in a joint assembly clamped in the groove of the intermediate support and optical fibres clamped in the grooves in the surfaces of the outer supports will be in substantially axial alignment: and, retractable between the intermediate support and each outer support, transversely extending means for initially positioning the leading ends of optical fibres to be clamped in the grooves in the surfaces of the outer supports substantially equal distances from the central transverse axis of the groove in the surface of the intermediate support, the arrangement being such that, after a joint assembly has been clamped in the groove of the intermediate support and optical fibres, with their leading ends abutting said transversely extending positioning means, have been clamped in the grooves of the outer supports, said transversely extending positioning means is withdrawn and the outer supports are moved in unison towards the intermediate support to cause the optical fibres carried by the outer supports to be introduced into opposite ends of said elongate space in the joint assembly.

2. Apparatus as claimed in Claim 1, wherein the surfaces of the intermediate and outer Supports have two or more than two sets of aligned grooves, each set of aligned grooves extending substantially parallel to the direction of motion of the outer supports so that the apparatus can be employed to effect simultaneously two or more than two optical fibre butt joints.

3. Apparatus as claimed in Claim 1 or 2, wherein the means for effecting movement, in unison, of the outer supports in a direction towards or away from the intermediate support comprises a shaft which, over a part of its length, is in screw threaded engagement with one of the outer supports and which, over another part of its length, is in screw threaded engagement with the other outer support, the screw thread over one part of the shaft being of opposite hand to the screw thread over the other part of the shaft and the outer supports being restrained against rotational movement with respect to the shaft so that, by appropriate rotation of the shaft, the outer Supports can be moved, in unison, towards or away from the intermediate support.

4. Apparatus as claimed in any one of the preceding Claims, wherein the transversely extending means for positioning leading ends of optical fibres supported in the grooves of the outer supports at equal distances from the central transverse axis of the groove in the surface of the intermediate support comprises a pair of arms each of which is pivotally or slidably mounted on the intermediate support between the intermediate support and one of the outer supports and each of which has, remote from the intermediate support, a substantially flat surface lying in a plane substantially normal to the common axis of the grooves in the surfaces of the supports.

5. Apparatus as claimed in Claim 4 in which the pair of arms are pivotally mounted on opposite faces of the intermediate support, wherein the end of each arm remote from the pivotal axis is integral with or connected to the end of the other arm.

6. Apparatus as claimed in any one of the preceding Claims, wherein the means for clamping a joint assembly of the kind described in the groove in the surface of the intermediate support and the means for clamping an optical fibre in the groove in the surface of each outer support each comprises a transversely extending elongate member which, at one of its ends, is pivotally mounted on the support and which, at the other of its ends, has an aperture through which a clamping screw can be screwed into a tapped hole in the surface of the support.

7. Apparatus for effecting controlled introduction of a pair of optical fibres into opposite ends of the elongate space in a joint assembly of the kind described substantially as hereinbefore described with reference to and as shown in the accompanying drawing.