GB2275786A - C-shaped optical fibre splice storage tray - Google Patents

Abstract

An optical fibre splice storage tray 40 is C-shaped in section. A splice closure comprises a tubular cover 30 and the C-shaped optical fibre splice storage tray 40 is arranged to extend concentrically inside the cover 30 when the closure is sealed. The storage tray 40 may have ridges 44 to hold splices 45, hook elements 48 of a hook-and-pile type fastener to hold individual fibres, apertures 43, 46, slots 49, funnel-shaped ports 42 and clip 32 for mounting a passive optical device 33 eg. a fibre splitter. Heat-shrinkable sleeves (47, Fig. 1) may seal cable entry ports (16, Fig. 1). <IMAGE>

Description

optical Fibre Stol This invention relates to an arrangement for storing optical fibres and/or optical fibre splices within a splice enclosure.

Optical fibres are widely used to carry communications signals through underground ducts. The fibres frequently have to be spliced to other fibres e.g. at a point where a cable carrying the fibres divides. The splices between the fibres have to be stored in trays which protect the splices, and which may also house excess lengths of fibres. These trays are mounted in waterproof closures inside the ducts. It will be appreciated that the closures need to be small so that they can be mounted inside the ducts, and thus various methods of increasing the storage capacity of smaller closures has been proposed. It is difficult to reduce the size of the closures owing to the maximum bending radius of the fibres inside the closure, therefore existing splice closures tend to be bulky, and those which are more compact are complicated and expensive to manufacture.

We have now devised an arrangement for storing optical fibres which is compact and cheap to manufacture and which may be mounted in underground ducts or above ground e.g. on telegraph poles In accordance with this invention as seen from a first aspect, there is provided a splice closure comprising a tubular cover, a tray which is generally C-shaped in section for receiving elements to be stored and means which mounts the tray generally concentrically inside the tubular cover.

The surface area of the tray is large so that it can store a large number of splices and/or coils of fibres.

However because the tray is generally C-shaped in section it will occupy considerably less space than a conventional flat tray. Thus the overall size of the closure can be reduced.

Preferably the tray is mounted to a base of the closure having cable entry ports which project axially of the cover.

Preferably the outer side of the tray is open so that when the cover is removed the elements stored in the tray are easily accessible. Preferably the outer side of the tray is provided with a removable cover. Means may be provided for retaining coils or loops of optical fibres stored in the Cshaped tray. These retaining means may comprise fingers which project towards the centre of the tray, or hook elements of the so-called hook-and-pile type fasteners.

Preferably the tray is provided with fibre entry and exit apertures in its side walls. A plurality of these apertures are preferably directed towards the base of the closure. Further apertures are preferably directed along a line which is concentric with said tubular cover.

Also, in accordance with this invention as seen from a second aspect, there is provided an optical fibre splice storage tray which is C-shaped in section.

An embodiment of this invention will now be described by way of example only and with reference to the accompanying drawings, in which: FIGURE 1 is a bottom view of a splice closure in accordance with the first aspect of this invention; FIGURE 2 is a longitudinal section through the splice closure on the line II-II shown in Figure 1, when its cover is fitted; FIGURE 3 is a longitudinal section through the splice closure on the line III-III shown in Figure 1, which its cover is removed; FIGURE 4 is a plan view of the splice closure shown in Figure 3; FIGURE 5 is a rear view of an optical fibre splice storage tray in accordance with the second aspect of this invention; FIGURE 6 is a plan view of the optical fibre splice storage tray of Figure 5; FIGURE 7 is a front view of the optical fibre splice storage tray of Figure 5; and FIGURE 8 is a front view of the optical fibre splice storage tray of Figure 5, shown in a flattened out condition.

Referring to Figures 1 to 4 of the drawings, there is shown a splice closure which comprises a base 10 and a tubular cover 30, each of plastics material. The base 10 comprises a tubular portion 12 and an end wall 14, with a plurality of tubular projections e.g. 16 extending outwards from its end wall 14 and forming cable entry ports. The tubular portion 12 has a peripheral surface formed with a groove 20, and edge of the groove being formed by a ring 22 applied to the end of the tubular portion 12 of the base. The peripheral surface of the tubular portion 12, within the groove 20, tapers in the axial direction and carried an 0-ring 24. The tubular cover 30 is closed at one end and its other end is dimensioned as a sliding fit over the outside of the tubular portion 12, so as to seal the cover 30 to the base 10.

Referring to Figures 5 to 8, an optical fibre splice storage tray 40 comprises a rectangular tray having a base 41, opposite end walls 31, 31 and upper and lower side walls 34, 35. The tray 40 is C-shaped in section such that its base 41 is curved through approximately 1800, and its side and end walls 31, 31, 34, 35 project radially outwardly from the curved base 41. The tray thus has a convex front or outside.

The tray enables optical fibres to be coiled inside the tray. Splices 45 between fibres are held in place between a pair of ridges 44. A plurality of side-by-side ridges 45 extend in a line between opposite end walls 31, 31 of the tray 40, so that a plurality of splices can be stored. The fibres e.g. 36 are retained inside the convex tray 40 by fingers (not shown) which- project from the side and end walls of the tray 40 towards its centre. Also, hook elements 48 of a hook-andpile type fastener may be provided to hold individual fibres in place.

The tray 40 is provided with apertures 43, 46 in its lower side and end walls 35, 31 which allow cables carrying bundles of optical fibres 50 or individual optical fibres 51 to enter and leave the tray 40. Slots 49 are formed in the base 41 at each aperture 43, 46 for fastening the cables 50 or fibres 51 to the tray 40 using cable ties. Two pairs of funnel-shaped ports 42 are formed in the base 41 of the tray, which ports 42 are directed towards the opposite ends of the tray. Fibres or bundles of fibres 53 may leave the trays 40 through these ports 42. Additionally a clip 32 may be disposed on the rear of the tray 40 for mounting a passive optical device 33 such as a fibre splitter. The fibres connected to the device 33 also pass through the funnel-shaped ports 31.

A bracket 25 mounts the tray 40 to the base 10 of the closure such that the tray 40 extends concentrically with the tubular cover 30 when the closure is sealed. The apertures 43 in the lower side wall 35 of the tray are directed towards the cable entry ports 16. Cables and fibres 50, 51, 53 enter and leave the closure via the cable entry ports 16, and heatshrinkable sleeves 47 or mechanical-type seals may provide an effective seal between the ports 16 and the cables or fibres.

Claims (1)

1. (1) A splice closure comprising a tubular cover, a tray which is generally C-shaped in section for receiving elements to be stored and means which mounts the tray generally concentrically inside the tubular cover.

   (2) A splice closure as claimed in claim 1, in which the tray is mounted to a base having cable entry ports which project axially of the cover.

   (3) A splice closure as claimed in any of claims 1 or 2, in which the tray comprises side walls having entry and exit apertures for optical fibres.

   (4) A splice closure as claimed in claim 3, in which a plurality of the entry and exit apertures are directed towards the base.

   (5) A splice closure as claimed in claims 3 or 4, in which a plurality of the entry and exit apertures are directed along a line which is concentric with said tubular cover.

   (6) A splice closure as claimed in any preceding claim, in which the radially outer side of the tray is open.

   (7) A splice closure as claimed in claim 6, in which a removable cover is provided for closing said outer side of the tray.

   (8) A splice closure as claimed in any preceding claim, comprising means for retaining coils or loops of optical fibres in the tray.

   (9) A splice closure as claimed in claim 8, in which the retaining means comprise fingers which project towards the centre of the tray.

   (10) A splice closure as claimed in claim 8, in which the retaining means comprise hook elements of hook-and-pile type fasteners.

   (11) A splice closure substantially as herein described with reference to the accompanying drawings.

   (12) An optical fibre splice storage tray which is C-shaped in section.

   (13) An optical fibre splice storage tray substantially as herein described with reference to the accompanying drawings.