GB2286060A - Optical fibre splice tray - Google Patents

Abstract

A splice tray 10 for storing splices between optical fibres comprises a central splice storing area 12 surrounded by a peripheral boundary wall 14. Fibre guiding and storing means 50 may be present in the central splice storing area 12. One or more fibre entry ports 18, 20, 22, for guiding and feeding optical fibres into the splice tray 10 pass through, and may be distributed around, the peripheral boundary wall 14. <IMAGE>

Description

MANAGEMENT OF OPTICAL FIBRES The present invention relates to the management of optical fibres.

The physical management of optical fibres presents considerable problems to telecommunications engineers.

These problems arise principally because (a) optical fibres are generally sensitive to mishandling and in particular may be damaged by being curved more tightly than a critical radius; and (b) when optical fibres are installed, extra lengths of fibre are often produced which must be gathered and maintained safely and, as far as possible, prevented from becoming tangled.

A particular problem with fibre management arises where fibres are spliced and in particular where a large bundle of fibres is connected to a number of smaller bundles or where a bundle of fibres is connected to a number of patch cords. In such situations, the splices must be fixed to a support structure and the fibres and/or patch cords must be fed to and from the splices, along suitably curved paths.

A further complication may be that the nature of the coatings of one number of fibres may differ to that of another number of fibres. Different coatings may mean that the respective outer diameters of the coatings which coat the fibres differ.

Hitherto, there have been available various splice trays which provide means for location of the splices themselves together with fibre holding means specifically adapted for use in the interconnection of particular groups of fibres. These arrangements have the disadvantage that the specific nature of the splice trays has meant that few engineers become familiar with more than a small portion of the types of trays available, so the range of fields in which these engineers can operate efficiently is limited.

Furthermore, any organisation which deals with the installation and maintenance of a large network of optical fibres will inevitably need to maintain stocks of a large variety of splice trays, with the attendant overheads of capital tied up in stock and a large storage space requirement.

The present invention aims to provide a splice tray for convenient management of optical fibres in a wide variety of applications.

According to a first aspect of the invention there is provided a splice tray comprising a splice area having a peripheral boundary, there being through that boundary a multiplicity of ports through which fibres may pass into or out of the splice area, the ports being distributed around the peripheral boundary.

Preferably the ports are adapted to receive fibres having coatings of different outer diameters.

Alternatively or additionally the ports may be adapted to receive bundles of fibres, the bundles being of different sizes.

By providing ports which are adapted to receive fibres of different sizes (that is the outer diameter of their coatings), the tray may be used in many applications and circumstances, so minimising the number of different items which must be held in stock to permit construction of a wide variety of fibre management systems and, further, minimising the number of components with which engineers must familiarise themselves.

Preferably, the splice tray further comprises at least one clamping location associated with one of the ports, the clamping location being adapted to receive a clamping means to clamp a fibre or group of fibres passing through the associated port. Preferably a plurality of clamping locations are associated with each of the ports. In this arrangement, clamping means (of which there may be provided a variety of different types) need be applied only where they are required, allowing the tray to be further configured for a particular application.

A further problem that arises in managing optical fibres lies in ensuring that the fibres follow a suitable path within a splice area, and to help overcome this problem it is known to provide guide means in a splice tray within the splice area.

However, it still happens that the fibres may be mis-routed in the tray.

In a second of its aspects, the invention provides a splice tray having a splice area and a peripheral boundary, there being through that boundary a port through which fibres may pass into or out of the splice area, the port being adapted to guide a fibre passing therethrough to guide means within the splice area.

By this arrangement, the risk of the fibre being incorrectly routed (with a risk of damage) within the splice area is minimised. The arrangement also provides an additional advantage of facilitating and quickening installation of fibres in the tray.

The port may guide the fibre in a curved path.

For example, the port may guide the fibre in a direction generally radial of a central point of the tray as it emerges externally of the splice area, and generally or partially circumferentially of the central point within the splice area.

The tray may comprise a plurality of said ports.

The ports may be grouped or may be evenly distributed around the tray. Where the ports are grouped, the ports within a group may be directed such that the fibres passing through each port in the group are similarly-directed.

Ports of both aspects of the invention may comprise an open-topped channel through the boundary.

There may be provided one or more lugs each projecting inwardly of the channel close to the open top thereof.

The lugs serve to retain the fibres in position in the channel.

Embodiments of the invention will now be described in detail by way of example with reference to the accompanying drawings in which: Figures 1 and 2 are, respectively, perspective and plan views of a splice tray embodying the invention; and Figure 3 shows a possible arrangement of fibres in the tray of Figures 1 and 2.

Figures 4A and 4B show the tray of Figures 1 and 2 installed in a supporting tray; Figure 5 shows a splice tray being a second embodiment of the invention, together with a lid therefor; Figure 6 shows a splice tray being a third embodiment of the invention; and Figure 7 shows a splice try being a fourth embodiment of the invention.

With reference to the drawings, a splice tray 10 embodying the invention is formed as a unitary plastics moulding of generally rectangular plan outline, and thin, rectangular section.

The splice tray comprises a generally oval splice area 12, surrounded by a peripheral boundary 14. The major axis of the splice area passes close to opposite corners of the tray 10. The splice area 12 comprises a generally planar surface of the splice tray 10, the boundary 14 comprising formations projecting normally from the plane. Within the splice area 12, there is mounted a splice holder 16 (shown in Figure 2) on which the splices themselves may be retained.

The boundary 14 is formed with a multiplicity of ports 18,20,22 of various types, through each of which an optical fibre or a group of fibres may be fed.

A first type of port 18 is adapted for use with a single fibre or a small bunch of fibres 10. Twelve ports 18 of the first type are provided in the present embodiment, disposed in two groups of four ports 18 and two groups of two ports 18. Each port 18 of the first type is formed as a channel through the boundary 14, the channel having an open mouth directed away from the plane of the splice area 12 and a flat base parallel thereto, and displaced therefrom towards the mouth.

The channel of each port 18 has an inner portion 18' proximal to the splice area 12 and an outer portion 18" remote from the splice area 12. The inner portion 18' closely confines a fibre 40 passing therethrough, and controls the orientation of the fibre 40 as it enters the splice area 12. The fibres 40 are directed such that a plurality of fibres 40 passing through respective ports of a group are each directed to the same region of the splice area 12. The inner portion 18' may be suitably curved to achieve the desired orientation of the fibre 40 passing therethrough. The outer portion 18" is broader than the inner portion 18' and allows some freedom for the orientation of a fibre 40 exiting therefrom to be varied in accordance with the arrangement of peripheral apparatus. The outer portions 18" of the channels of the various ports 18" are arranged to permit fibres 40 to pass thereinto a wide range of orientations, so permitting connection to external apparatus disposed around the tray 10.

At each outer portion 18", a plurality of lugs 24 project into the channel, the lugs 24 being thin and disposed close to the channel's open mouth. Each channel has at least two lugs 24, spaced apart along the channel and projecting from opposite sides thereof. A fibre 40 passing through the port 18 is arranged to pass between the lugs 24 and the base of the channel. The lugs 24 are arranged such that flexing of the fibre 40 in an S-shaped curve allows the fibre 40 to be inserted into and removed from the channel past the lugs 24, yet when the fibre 40 is in its natural, straight or simply-curved state, its passage out of the port 18 through the open mouth is resisted.

The channel of each port 18 is curved such that the ports 18 within a group can receive fibres 40 from outside the tray 10 over a range of orientations while within the splice area 12, the fibres 40 passing through each port 18 in a group are similarly directed. In this embodiment, all fibres 40 entering the splice area through a group of ports are directed towards a common guide 50 (to be described below).

A second type of port 20 is adapted for use with larger bundles of fibres 42. Two such ports 20 are provided on the tray 10 of the present embodiment at diametrically-opposed corner regions thereof.

The port 20 of the second type comprises an open-mouthed, flat-bottomed, straight channel of width somewhat broader than the channel of a port 18 of the first type. Two lugs 26 project into the channel in a manner similar to the lugs 24 of a port 18 of the first type, the lugs 26 of a port 20 of the second type being somewhat larger. The flat bottom of the channel is substantially coplanar with the plane of the splice area 12, thus making the channel of a port 20 of the second type deeper than the channel of a port 18 of the first type.

Adjacent the channel, and close to the periphery of the tray 10, there is provided a clamping location comprising a pair of planar recesses 30 in the boundary 14 on opposite sides of the channel. A hole 32 through the tray 10 is provided in each recess, the holes 32 being disposed such that a line interconnecting their centres is transverse to the channel. A fibre 42 passing through the port 20 may be retained by fixing a securing means, such as a resilient plastics strip 34 to the recesses 30, for example by screws 36 passed through the holes 32, so as to clamp the fibre 42 between the strip 34 and the bottom of the channel. On the underside of the tray 10, there may be provided a recess surrounding each hole 32 for receiving a nut for the screw 36. The recess may be hexagonally-shaped and of substantially the same diametrical size as the nut such that the nut is retained in place prior to and during tightening.

Ports 22 of a third type are provided, in the present embodiment, in two groups of three, the groups being close to opposite edges of the tray 10. The ports 22 of the third type are adapted to receive large bundles of fibres 44 or patch cords. Each group of ports 22 is formed as a gap in the boundary 14, in which there are two circular, flat-topped projections 37, each having a central hole 38 extending through the tray 10. Portions of the boundary 14 adjacent the gap have recesses 30 and holes 32, similar to those described above. Thus, each port 22 of the third type is defined between the two circular projections 37 or between one of them and the extremity of the gap in the boundary 14. A fixing means, for example a plastics strip 34, as described earlier, may be secured between adjacent holes 32, 38 to secure a bundle of fibres 44 in the port 22.

Within the splice area 12 there is provided a pair of fibre guides 50. The guides 50 each comprise a flat-topped projection from the plane of the splice area 12 substantially of the height of the boundary 14. In plan, each guide is arcuate, being just over a semi-circle. The convex vertical walls of the guides are oppositely directed, and their centres lying close to the major axis of the splice area, close to opposite ends thereof. Lugs 52 project from one end portion of each guide 50 parallel to and spaced from the plane of the splice area 12. The guides 50 are suitably curved such that fibres may be wrapped around them, thereby allowing a bend of up to 1800 of a safe radius to the formed in a fibre 40,42 within the splice area 12. Spare fibres may also be coiled around the guides 50, the lugs 52 resisting movement thereof away from the plane of the splice area 12.

A plurality of lugs 54 project into the splice area 12, spaced from its plane, from the boundary 14.

These retain spare fibres to be coiled around the interior of the boundary.

With reference to Figure 3, a cable of fibres 42 enters the splice tray 10 through a port of the second type 20, the cable 42 being clamped by a strip 34 as described above. Within the tray, the cable is split into individual fibres 42'. The fibres 42' are conducted in a curved path around the periphery of the splice area 12, and are guided to the splice holder 16. Within the splice holder 16, the fibres 42' are spliced to further fibres (for example, patch cords) 44 which are then conducted around the periphery of the splice area 12 to leave the tray 10 through a port of the second type 20. Alternatively, the further fibres could exit the splice tray 10 through a port of the first type 18, as shown at 40.

In Figures 4A and 4B, there is shown the splice tray 10 mounted on a supporting tray 60. The supporting tray 60 comprises a metal pressing having a rectangular base 62 of size larger than the splice tray 10, and walls 64 upstanding from the periphery of the base 62 along long and short sides thereof. From each of two opposing walls 64 on the short sides there projects perpendicularly a mounting flange 66, through each of which mounting holes 67 are provided.

Three oval holes 68 pass through the base 62. The holes 68 are disposed with their long axes aligned and parallel to the long sides of the base 62, and extend from close to one long side a distance approximately one quarter of the width of the base 62.

The splice tray 10 is mounted on the base 62 with its long axis parallel to the long axis of the base 62 and its short axis substantially coincident with the short sides of the base 62. A long edge of the tray is disposed close to the long side of the base 62 remote from the holes 68.

A right-angled corner portion 70 (referred to as the cut-away section) of the base 62 extending between the long side proximal to the holes 68 and a short side of the base is cut away as are co-extensive portions of the side walls 64. A socket mounting plate 71 is mounted on an end portion of the said long side remote from the cut-away section 70, and on a proximal portion of the adjacent short side wall 64.

First and second fibre guides 72,74 are provided within the supporting tray 60. Each guide 72,74 comprises a wall portion upstanding perpendicularly from the base 62 and an attachment portion for securing the guide to the base. The wall portion of each guide 72,74 is shaped to define a path for fibres within the supporting tray 60. The wall portion of the first guide 72 extends from a short side wall 64 close to the cut-away section 70 to guide a fibre or a conduit from the cut-away section 70, between two of the holes 68, towards the splice tray 10. The wall portion of the second guide 74 extends from under the socket mounting plate 71 to guide a fibre or a conduit therefrom, either between the said two holes 68 or towards the first guide 72 and the cut-away section 70, as required.

A semi-circular hole 76 is provided in the base 62, its straight boundary being parallel with a short side thereof and its arcuate side being directed towards the splice tray 10. The hole 76 may provide a path through the base 62 for a fibre.

In one arrangement, a fibre cable 80 (which includes a plurality of optical fibres and electrical conductors) enters the supporting tray 60 through the cut-out section 70, adjacent which it is secured by a clamp 82. From there, the cable 80 runs adjacent the first guide 72 and ends adjacent one of said two holes 68, where it is secured by a second clamp 84. A copper conductor 86 runs therefrom towards the socket mounting plate 71 for connection to sockets mounted thereon. First and second fibres 88,90 are directed towards the splice tray 10, entering the tray through adjacent ports of the first type 18. The first and second fibres 88,90 are spliced within the splice tray 10 to a patch cord 92 which leaves the splice tray 10 through a port of the third type 22 and then leaves the supporting tray 60 through the hole 76.

Supporting trays 60 of this type may be mounted in racks, each rack holding a multiplicity of trays 10.

The holes 68 may provide a path for cooling air to pass through the rack.

The splice tray 100 illustrated in Figure 5 has many features in common with the splice tray 10 described above, and corresponding features have been given corresponding reference numerals.

The splice tray 100 comprises fibre guides 102 which serve the same purpose as the guides 50 described above. However, in this embodiment, the guides 102 comprise circular projections from the splice area 12.

Also provided in this embodiment are ports of a fourth type 104. Each port of the fourth type 104 comprises a wide opening through the boundary 14, being closed by a bar 106 extending across an outer portion thereof. A plurality of open slots extend transversely across the bar 106 through each of which a fibre may pass. A central divider 108 projects from the bar 106 into the opening, the opening and divider of each port 104 being shaped to direct fibres passing through the slots towards a respective guide 102.

A portion 14' of the boundary 14 extending along one of the shortest sides of the tray 100 is of uniform width and has a group of ports of the first type 18' extending therethrough.

The tray 100 is provided with a removable cover 110 which, when in place, covers the splice area 12 and the boundary cover 14, other than the said portion 14'. The cover 110 has a pair of circular apertures 112 which, when the cover is in place, overlie the guides 102 and serve to locate the cover 110 thereon.

With reference to Figure 6, a splice tray 120 being a third embodiment of the invention, is shown.

This tray 120 is very similar to the tray 10 described above with reference to Figure 1, but has slightly different dimensions and numbers of ports. The features of the splice tray 120 of the third embodiment are indicated by reference signs corresponding to those used in Figures 1 to 3.

With reference to Figure 7, a splice tray 10' being a fourth embodiment of the invention, is shown.

This tray 10' is very similar to the tray 120 described above with reference to Figure 6. The features of the splice tray 10' of the fourth embodiment are indicated by dashed reference numerals corresponding to those undashed numerals used in Figures 1 to 3.

Claims (19)

1. A splice tray comprising a splice area having a peripheral boundary, there being through that boundary a multiplicity of ports through which fibres may pass into or out of the splice area, the ports being distributed around the peripheral boundary.

2. A splice tray according to claim 1 in which the ports are adapted to receive fibres having coatings of different outer diameters.

3. A splice tray according to claim 1 or claim 2 in which the ports are adapted to receive bundles of fibres, the bundles being of different sizes.

4. A splice tray according to claims any one of the preceding in which guide means adapted to guide fibre is provided within the splice area.

5. A splice tray according to claim 4 in which the guide means comprises a pair of guide walls.

6. A splice tray according to any one of the preceding claims in which the tray has a plurality of sides.

7. A splice tray according to claim 6 in which at least one port is present in each side of the tray.

8. A splice tray according to any one of the preceding claims in which one or more of the ports is or are adapted to guide a fibre or fibres in a curved path.

9. A splice tray according to any one of the preceding claims in which comprises a plurality of said ports.

10. A splice tray according to any one of the preceding claims in which the ports are grouped in one or more groups around the tray.

11. A splice tray according to claim 9 in which the ports in a group or groups are adapted to direct fibres passing through each port in the group or groups in a similar direction.

12. A splice tray according to any one of the preceding claims which comprises at least one clamping location associated with one of the ports, the clamping location being adapted to receive a clamping means to clamp a fibre or group of fibres passing through the associated port.

13. A splice tray according to claim 12 in which a plurality of clamping locations are associated with each of the ports.

14. A splice tray according to any one of the preceding claims in which the ports comprise an open-topped channel through the boundary.

15. A splice tray according to any one of the preceding claims in which the ports comprise one or more inwardly projecting lugs.

16. A splice tray according to claim 15 as it depends from claim 14 in which the lugs are close to the top of the open-topped channel.

17. A splice tray having a splice area and a peripheral boundary, there being through that boundary a port through which fibres may Fss into or out of the splice area, the port being adapted to guide a fibre passing therethrough to guide means within the splice area.

18. A splice tray according to claim 17 in which there is a plurality of ports.

19. A splice tray substantially as described herein with reference to Figures 1, 2, 3, 4A and 4B; Figure 5; Figure 6; or Figure 7 of the accompanying drawings.