GB2298496A

GB2298496A - Optic fibre splice storage tray and assembly thereof

Info

Publication number: GB2298496A
Application number: GB9503971A
Authority: GB
Inventors: Raymond Charles Foss
Original assignee: Bowthorpe PLC
Current assignee: Bowthorpe PLC
Priority date: 1995-02-28
Filing date: 1995-02-28
Publication date: 1996-09-04
Anticipated expiration: 2015-02-28
Also published as: GB2298496B; GB9503971D0

Abstract

An optical fibre splice storage tray comprises an elongate base 20 and a peripheral wall 23. A plurality of projections 27,28,32,33 may extend parallel to the base 20 towards its centre for supporting coils of optical fibres. One coil of fibre extends around the periphery of the tray and the other coil is disposed at one end of the tray. A series of splice-retaining channels 24, inclined relative to the longitudinal axis of the base, extend across the base 20 intermediate its opposite ends. In use fibres entering and leaving the tray form a coil around the periphery of the base 20. The fibres are routed from the peripheral coil to the other coil in a figure-of-eight fashion, so that any splices can be located in the inclined channels 24. Several splice storage trays may be stacked and pivotally mounted to a base of an enclosure (Fig. 1).

Description

Optical Fibre slice Storage Arrangements This invention relates to a optical fibre splice storage arrangements.

Hitherto, splices between optical fibres have been stored in trays. Such trays generally comprise a plurality of parallel ridges or channels which hold the delicate splices, and a peripheral region in which excess fibre can be coiled.

Severe attenuation can occur in optical fibres if they are formed into tight bends, thus the size of any splice storage tray is governed by the minimum radius to which the fibre being used can be bent.

The most common splice tray are circular or rectangular in shape with at least two projecting entry ports. In use, the fibre to be spliced enters one port and is coiled several times around the periphery of the tray. The fibre then curves inwardly towards one of a number of parallel splice-retaining channels in the centre of the tray, where it is joined to a second fibre which leaves the tray through the other port. The diameter of the tray thus needs to be much greater than the minimum bending radius of the fibre, so that the fibres can pass to splice-retaining channels at the centre of the tray, without exceeding the minimum bending radius of the fibre.

Often it is desirable to route fibres into and out of the tray through the same port. A considerable amount of bending of the fibre is thus required in order to route a fibre in and out of the tray through the same port, and also retain its splice in one of the central splice-retaining channels.

It will be appreciated that the tray thus either needs to be very long, or very wide.

In modern communications ducts space is very limited, and thus large optical fibre splice storage enclosures for enclosing correspondingly large trays are not favoured.

We have now devised an optical fibre splice storage tray which alleviates the above-mentioned problems.

In accordance with this invention, as seen from a first aspect, there is provided an optical fibre splice storage tray comprising an elongate base, means for storing a first coil of optical fibre around the periphery of the tray, means for storing a second coil of optical fibre at one end of the tray, and at least one series of splice retaining means disposed on a line extending across the base intermediate its opposite ends, the splice retaining means being inclined relative to the longitudinal axis of the elongate base.

In use, fibres entering and leaving the tray form the first coil of fibres around the periphery of the base. The splices in the fibres are located as the fibres pass on an inclined path from the first to the second coil in a figure-ofeight fashion. The width of the tray does not need to be significantly larger than width required to accommodate fibre formed into a coil having the minimum permitted bending radius.

The length of the tray does not need to be significantly longer than the length required to accommodate two such coils side-byside.

Preferably the tray comprises two series of spliceretaining means (e.g. channels) disposed on said line which extends across the base, the channels of the two series converging towards said one end of the tray.

Preferably the means for storing said first and second coils are arranged to overlap the first and second coils at said one end of the tray.

Preferably the means for storing said first and second coils comprises a plurality of elongate projections which project parallel to the base.

Preferably the projections for storing the second coil are arranged to store a substantially circular coil, the projections extending radially to the centre of the coil.

Preferably the tray comprises at least one cable entry port on an end of the base.

In use, the trays may be mounted axially inside an enclosure which comprises an elongate tubular cover that is formed from moulded plastics. The cover tapers slightly from its open end to its closed end, so that it can be removed from the mould core. Thus, preferably the tray tapers outwardly from said one end towards its opposite end, so as to fit closely inside the cover.

A plurality of trays may be mounted in a stack inside the enclosure. It is often necessary to feed a fibre from one tray to another, and hitherto, this has been achieved by routing the cable through the ports of the respective trays.

A disadvantage of this arrangement is that a bend has to be formed in the fibres, which has to be accommodated in the base of the enclosure. A complicated array of fibres can thus exist when there are several connections between trays.

Thus, in accordance with this invention, as seen from a second aspect, there is provided an optical fibre splice storage tray comprising a base and means for storing a coil of optical fibre on the tray, an elongate aperture being formed in the base of the tray, the aperture being arranged to act as a port for fibres entering or leaving the tray.

The aperture is elongated so that the fibres can travel substantially in the plane of the base as they pass between trays. Hence, any external bending of the fibres is avoided.

Preferably the aperture is arcuate, so that the fibres can coil between trays.

Preferably the means for storing the coil of optical fibre is arranged to store the coil over the aperture in the base.

In an optical fibre splice storage enclosure comprising a plurality of trays mounted in a stack, it is difficult to gain access to trays in the middle of the stack. It has been proposed to hinge each of the trays along one edge to a base of the enclosure, however a disadvantage of this arrangement is that several trays have to be pivoted forwards in order to gain access to one of the trays behind.

Thus, in accordance with this invention, as seen from a third aspect, there is provided an optical fibre splice storage assembly comprising an enclosure and a plurality of parallel optical fibre splice storage trays arranged in a stack inside the enclosure, each tray being pivotally mounted to a base of the enclosure by means of a pivot arranged to enable the trays to pivot within their respective planes.

Thus, in order to gain access to a tray at the centre of the stack, it can be pivoted sideways out of the stack without moving the other trays.

Preferably the pivots are also arranged to enable the tray to pivot out of their respective planes i.e. forwards or backwards.

Preferably the pivots comprises ball joints.

Preferably the trays are mounted in a stepped manner to the base, with the outer trays in the stack being arranged nearer to the base than the trays at the centre of the stack.

Thus, the outer trays can be pivoted entirely out of the way to give unobstructed access to the trays behind.

Preferably the trays are mounted to a rotatable carrier on the base, which enables the stack of trays to be oriented in any direction.

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 longitudinal sectional view through an optical fibre splice enclosure, which houses a plurality of optical fibre splice storage trays in accordance with this invention; and FIGURE 2 is a plan view of one of the optical fibre splice storage trays that are housed inside the enclosure in of Figure 1.

Referring to Figure 1 of the drawings, there is shown an optical fibre splice enclosure 10 which houses a plurality of optical fibre splice storage trays 11. The enclosure 10 comprises a circular base portion 12 having a plurality of tubular cable entry ports 13 projecting from one side. The trays 11 are pivotally mounted to a carrier 14 which is fixed to the opposite side of the base 12.

The carrier 14 comprises a V-shaped element 15 having arms which are directed outwardly and rearwardly towards the base 12. A plurality of circular sockets are formed on the carrier 14 for receiving complementary shaped balls projecting from the trays 11. The V-shaped element of the carrier 11 is supported by a splined stem 17, which can be engaged with the base 12 at a plurality of rotary positions about its axis.

Referring to Figure 2 of the drawings, there is shown an optical fibre splice storage tray 11 which can be connected to the carrier 14 on the base of the enclosure. The tray 11 comprises an elongate flat base 20 having semi-circular portions at its opposite ends. A mounting lug 21 projects from a first end of the base 20. The lug 21 is provided at its free outer end with a ball 22 which snap-engages into one of the apertures in the carrier 14. The longitudinal sides of the base 20 taper slightly inwardly from the first end of the tray towards the second end. A substantially continuous peripheral wall 23 extends around the base 20. The base is formed with two series of parallel ridges 24, one series either side of the base. The ridges 24 are formed on a line which extends transversely across the base intermediate its opposite ends.

The ridges 24 are disposed slightly nearer the first end of the base than the second. Adjacent ridges 24 define channels to receive and retain optical fibre splices.

A first optical-fibre storage region 25 is disposed between the ridges 24 and the first end of the base. A second optical-fibre storage region 26 is likewise disposed between the ridges 24 and the second end of the base. The first region 25 comprises two elongate projections 27, which extend parallel to the base 20 towards a central point of the region, from the top edge of the peripheral wall 23 on opposite side edges of the base. A third elongate projection 28 projects towards the central point of the region, from the top edge of the arcuate portion of the peripheral wall 23 on the first end of the base.

The two series of ridges 24 are arranged, such that their respective parallel ridges converge towards the second end of the base. At the outer ends of the two series of ridges, upstanding walls 29 are disposed parallel to, but away from the outer peripheral wall 23. The walls 29 curve inwardly towards the second region 26 of the tray. A second set of upstanding walls 30 are disposed parallel to, but away from the outer peripheral wall 23 towards the second end of the tray.

The walls 30 carry respective elongate projections 31 which extend parallel to the base towards the centre of the second region 26 of the tray. A third elongate projection 32 projects towards the centre of the second region 26 from the arcuate portion of the peripheral wall 23 at the second end of the tray. Also, two small semi-circular projections 33 extend towards the centre of the second region of the tray from the peripheral wall 23 on opposite side edges of the base. Two small projections 34 extend from the peripheral wall 23 on opposite side edges of the base, at a point between the upstanding walls 29,30. The free outer end of the projections 34 terminate adjacent respective upstanding walls 35. One end of the walls 35 lies generally parallel to the arcuate ends of respective walls 29.The opposite end of the walls 35 are curved outwardly, so that they extend along respective diverging lines that lie tangentially to an imaginary circle centred about the centre of the second region 26. The wall 35 supports respective inwardly directed projections 36.

The tray 11 is preferably formed from moulded plastics, and thus each of the projections e.g. 27 is arranged over an aperture e.g. 37 which enables the mould cores to be separated once the tray is moulded. A pair of curved apertures 38 are formed in the base at the second end of the tray. The apertures 38 extend parallel to the arcuate portion of the peripheral wall 23 at the second end of the tray.

Outwardly-directed projections 39 are disposed on respective walls 29, in line with the ridges. There are recesses 40 in the walls 23 on either side of these projections 39, and there are corresponding recesses 41 in the peripheral wall 23.

Each end of the tray comprises a pair of fibre entry ports 42, which extend parallel to the peripheral walls 23 along the side edges of the base. Each port 42 is formed with two apertures 43 in its floor.

In use, a fibre to be spliced enters the tray through a tube (not shown), which is anchored to one of the cable entry ports 42 by means of cable ties passed through the apertures 43. The fibre is then wound several times e.g. in a clockwise direction around the periphery of the tray in order to accommodate any excess fibre. The projections 27,32,33,34 help to keep the excess fibre in place. The fibre can also be coiled around the second region 26 at the end of the tray. The projections 31,32,33 help to keep the coil of excess fibre in place in the second region 26 of the tray. The fibre then passes from the second region 26 to one of the splice-retaining channels which are directed towards the exit port 42 for the fibre.

The splice in the cable is inserted into one of the splice-retaining channels and the fibre then continues in an arcuate path in an anti-clockwise direction around the tray before it leaves the tray through the same port as it entered.

The tray can also be configured so that the fibres enter and leave the tray through different ports. Also, the retaining channels may hold optical splitters, with say the main trunk cable entering and leaving the tray through the same port and the branch leaving the tray through a second port.

A rubber band is engaged around the projections 39 and over the ridges 24 to hold the splices and/or splitters in place: the band located in the recesses 40,41 in the walls 29,23 respectively.

Referring again to Figure 1 of the drawings, each tray 11 is pivotally mounted to the carrier 14, so that it can be pivoted away from the other trays in order to gain access to the splices. Accordingly, the trays 11 are attached to the carrier 14 in a stepped fashion, so that several trays can be pivoted forwards to gain access to the trays behind.

A tubular cover portion 19 fits onto the circular base to enclose the trays 11. A rubber band is applied around the trays 11 to hold them together before the cover is fitted. The side edges of the trays 11 taper towards the second end, so that they fit inside the cover 19, which also tapers owing to the draw of the moulding tool.

The fibres feeding each tray enter the enclosure 10 in cables which pass through the cable entry ports 13 on the base 12. When the cover 19 is fitted the trays lie in a plane which extends parallel to the axis of the ports 13.

Claims

1) An optical fibre splice storage tray comprising an elongate base, means for storing a first coil or optical fibre around the periphery of the tray, means for storing a second coil of optical fibre at one end of the tray, and at least one series of splice retaining means disposed on a line extending across the base intermediate its opposite ends, the splice retaining means being inclined relative to the longitudinal axis of the elongate base.

2) An optical fibre splice storage tray as claimed in claim 1, in which the tray comprises two series of spliceretaining means disposed on said line which extends across the base, the splice retaining means comprising channels, the channels of the two series converging towards said one end of the tray.

3) An optical fibre splice storage tray as claimed in claims 1 or 2, in which the means for storing said first and second coils are arranged to overlap the first and second coils at said one end of the tray.

4) An optical fibre splice storage tray as claimed in any preceding claim, in which the means for storing said first and second coils comprise a plurality of elongate projections which project parallel to the base.

5) An optical fibre splice storage tray as claimed in claim 4, in which the projections for storing the second coil are arranged to store a substantially circular coil, the projections extending radially to the centre of the coil.

6) An optical fibre splice storage tray as claimed in any preceding claim, comprising at least one cable entry port on an end of the base.

7) An optical fibre splice storage tray as claimed in any preceding claim, in which the tray tapers outwardly from said one end towards its opposite end.

8) An optical fibre splice storage tray as claimed in any preceding claim, in which an elongate aperture is formed in the base of the tray, the aperture being arranged to act as a port for fibres entering or leaving the tray.

9) An optical fibre splice storage tray as claimed in claim 8, in which the aperture is arcuate.

10) An optical fibre splice storage tray as claimed in claim 9, in which the means for storing the second coil of fibre is arranged to store the second coil of fibre over the aperture in the base.

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

12) An optical fibre splice storage assembly comprising an enclosure and a plurality of parallel optical fibre splice storage trays arranged in a stack inside the enclosure, each tray being pivotally mounted to a base of the enclosure by means of a pivot arranged to enable the trays to pivot within their respective planes.

13) An optical fibre splice storage assembly as claimed in claim 12, in which the and each pivot is arranged to enable its respective tray to pivot out of its respective plane.

14) An optical fibre splice storage assembly as claimed in any of claims 12 to 14, in which the pivots comprise ball joints.

15) An optical fibre splice storage assembly as claimed in claim 12, in which the trays are mounted in a stepped manner to the base, with the outer trays in the stack being arranged nearer to the base than the trays at the centre of the stack.

16) An optical fibre splice storage assembly substantially as herein described with reference to the accompanying drawings.