GB2293891A

GB2293891A - Optical fibre storage shelf having slidable and fixed trays

Info

Publication number: GB2293891A
Application number: GB9419416A
Authority: GB
Inventors: Peter David Jenkins
Original assignee: Miniflex Ltd
Current assignee: Miniflex Ltd
Priority date: 1994-09-27
Filing date: 1994-09-27
Publication date: 1996-04-10
Anticipated expiration: 2014-09-27
Also published as: GB2293891B; GB9419416D0

Abstract

An optical fibre storage shelf has two trays 12, 14 arranged one above the other. One of the trays 12 is fixed and the other 14 is slidable relative to the tray 12 in a plane generally parallel to the tray 12. Fibre connection terminals 22 at the back of the tray 12 and at the front of the tray 14 provide points to which fibres can be connected to and from the shelf. There are fibre guides (26, 28, 30, Fig. 3), 32 on the trays to control the bending radius of fibres mounted at one end on one tray and at the other end on the other tray, as the tray 14 slides relative to the tray 12, so that a predetermined bending radius is not exceeded. Fibre storage reels are shown. <IMAGE>

Description

OPTICAL FIBRE STORAGE SHELF In optical fibre networks, it is necessary to provide connections between large numbers of fibres in specific arrangements whilst allowing those fibres to be disconnected, reconnected and spliced. All of this has to take place in the minimum amount of space and without risking any damage to the fibres themselves.

Fibre management devices of various types and forms are known. Some are simple in construction and therefore lowcost but are difficult to install and do not allow simple subsequent handling of the fibres. Other devices are complex to allow a variety of different fibre terminations and/or configurations and to allow subsequent disconnection and reconnection, but are bulky and expensive.

According to the present invention, there is provided an optical fibre storage shelf comprising two trays arranged one above the other, a first of the trays being adapted for mounting in a fixed position; the second of the trays being slidable relative to the first tray in a plane generally parallel to the first tray, fibre connection terminals at the back of the first tray and at the front of the second tray; and fibre guide means on the trays adapted to control the bending radius of fibres mounted at one end on one tray and at the other end on the other tray, as the second tray slides relative to the first, so that a predetermined bending radius is not exceeded.

The first and second trays preferably slide relative to one another on runners similar to those used for kitchen drawers.

The first tray may be adapted to be mounted in a rack along with other shelves of a similar or of a different design.

The fibre connection terminals may terminate either fibres or fibre sheathing tubes, or both.

One of the trays (preferably the second tray) may carry fibre storage reels for storing lengths of fibre against the need to re-splice fibres at a later date. The fibre storage reels can have coaxial inner and outer circular tracks for holding fibre, with the cylindrical walls of the tracks being interrupted to allow fibre to pass from one track to the other, as well as into and out of the reels The invention will now be further described, by way of example, with reference to the accompanying drawings, in which:: Figure 1 is a schematic illustration of a shelf in accordance with the invention; Figure 2 is a plan view of a slidable shelf in accordance with the invention; Figure 3 is a plan view of a fixed shelf; Figure 4 is a front end view of the fixed shelf of Figure 3; Figure 5 is a view, partly in section on the line V V, on the front edge of the tray of Figure 3; Figure 6 is a plan view of a fibre storage reel; Figure 7 is a section on the line VII-VII from Figure 6; and Figure 8 is a section on the line VIII-VIII from Figure 6.

The shelf shown in Figure 1 has a fixed, lower tray 12 which will be fixed in a mounting rack, and a slidable upper tray 14. The lower tray 12 has side walls 16, 18 which can be mounted to the mounting rack in such a way that the tray 12 is held in a fixed position.

The slidable tray 14 is mounted on the fixed tray and can slide backwards and forwards above that tray using conventional sliding drawer hardware. Details of this hardware are omitted from Figure 1.

Both the upper and lower trays 12, 14 have upstanding front and back flanges 20 for supporting cables and/or cable terminals. These flanges may extend the full width or only part of the width of the tray edges, or may be omitted, for example from the front edge of the lower tray 12. The actual shape and form of the terminal receiving apertures 22 in the flanges 20 will depend upon the nature of the terminals to be received, as will the number of apertures 22. The apertures may receive actual terminals, in which fibres are terminated and connected with ends of other fibres, or they may just be designed to retain a fibre sheath as the fibre with its sheath passes onto the tray.

In order to allow optical fibre to follow a path from one of the trays to the other tray in all relative positions of the trays, guides are provided on the lower tray to make the fibre follow a S-shaped path from the front region of the lower tray to the back region of the upper tray. The profile of the S-shape will change as the upper tray slides relative to the lower tray, but as a result of the guiding means the fibre will never be forced to bend through a radius tighter than its pre-determined minimum radius of curvature.

Figure 3 shows a plan view of the tray 12 with, on the left hand side, the position of the rear edge of the slidable tray 14 in its fully retracted position shown at 14a and, on the right hand side, the position of the rear edge of the tray in its fully extended position shown at 14b. A fibre 24 enters the shelf through one of the terminal apertures 22 mounted in the back wall 20 of the tray 12. The fibre is then retained (with a number of other fibres) within fixed guides 26, 28, 30. These guides are all of a type which allow the fibre to be laid in from above and to then be trapped in the guides by the positioning of a lid on the guide. The fibre passes in a loop from the last of the guides 30 past a fixed wall 32 which ensures that the path followed by the fibre is the correct one leading onto the rear edge 14a of the upper tray 14.

When the tray is pulled out, so that its rear edge takes up the position indicated at 14b, the fibre has to follow the rear edge of the tray and takes up the position shown on the right hand half of Figure 3. In both of these fibre positions, the fibre will not bend beyond its minimum radius of curvature.

Also visible on the lower tray 12 is a conventional catch 34 which will engage with a corresponding striker bar on the underside of the upper tray 14, to hold the tray 14 in its normal, retracted position.

At the back edge of the upper tray, a terminal block 15 is mounted, to hold the fibres at the point where they pass onto the upper tray.

The upper tray 14 has a lid 36 to cover the tray contents once all the connections have been made. The lid can be hinged at one edge.

On the upper tray, two fibre storage reels 38 are provided. These reels have a number of turns of fibre wound around them so that a reservoir of fibre is held on the shelf. This enables there to be fibre available if connections have to be remade at some time in the future, by cutting out and discarding a section of fibre and then using fibre from the reservoir to make a new connection.

Each reel 38 has a central cylindrical space 40 into which fibre can be coiled, with the natural resilience of the fibre causing the coils to expand outwardly against the inner walls 42 of the space 40. These walls are interrupted by inner circumferential gaps 48. The radius of the walls 42 will be greater than the minimum bending radius to which the fibre can be safely subjected. The space includes radially extending flanges 44, and after fibre has been placed in the space against the walls, a foam plastic disk 46 can be placed inside the space 40 to retain the fibres.

The last few turns of fibre are taken from the space 40 through one of the inner circumferential gaps 48 into an outer annular track 50. A few turns are laid in this track, and the end of the fibre then exits the reel through one of four outer circumferential gaps 52. The fibre can then pass to a terminal at 22.

Two reels 38 are mounted on the upper tray and the reels may be independent of one another, each storing fibre for one part of the shelf, or they may work together with fibre being wound between the reels. This is particularly relevant when the fibre is in multiple bundle forms stored on a first reel, and is required to be broken out into single fibres for passing to a terminal at 22. In such circumstances a breakout manifold may be positioned between the reels and lengths of single fibre may be stored on the second reel, before passing to the terminal 22.

A storage shelf as described allows a number of fibres to be organised, terminated, spliced and connected on the one shelf. The height of the shelf is small, but because the upper tray can be easily pulled out and slid back in, it is possible to work on the fibres on the tray with ease.

The fibres may be handled on the shelf either with or without protective sheaths, and the clips, guides and terminal fittings will be designed accordingly.

When fibres without protective sheaths are being handled on the shelf, it may be preferable to provide flexible protective tubes to follow the S-shaped path from the front region of the lower tray to the back region of the upper tray to contain the fibres and to maintain a smooth rolling loop as the upper tray slides relative to the lower tray. When the fibres are of 'blown fibre' configuration it may be preferable for such tubes to be of blowable type and for the terminals in apertures 22 in flange 20 at the rear of the lower tray to be designed to connect such tubes to blowable tubes provided in the rack.

In such circumstances fibres may then be blown directly from or to the upper shelf without having to effect access directly to the tubes provided in the rack.

In the Figures, components which allow the upper tray to slide out relative to the lower tray are all indicated with the reference numeral 54. These components (primarily rollers and runners) can be obtained as readily available hardware components of the form used, inter alia, for kitchen drawer mountings.

Claims

1. An optical fibre storage shelf comprising two trays arranged one above the other, a first of the trays being adapted for mounting in a fixed position; the second of the trays being slidable relative to the first tray in a plane generally parallel to the first tray, fibre connection terminals at the back of the first tray and at the front of the second tray; and fibre guide means on the trays adapted to control the bending radius of fibres mounted at one end on one tray and at the other end on the other tray, as the second tray slides relative to the first, so that a predetermined bending radius is not exceeded.

2. An optical fibre storage shelf as claimed in Claim 1, wherein the first and second trays slide relative to one another on telescopic runners.

3. An optical fibre storage shelf as claimed in any preceding claim, wherein fibre connection terminals are provided to terminate fibres.

4. An optical fibre storage shelf as claimed in any preceding claim, wherein fibre connection terminals are provided to terminate fibre sheathing tubes.

5. An optical fibre storage shelf as claimed in any preceding claim, wherein fibre connection terminals are provided to terminate both fibres and fibre sheathing tubes.

6. An optical fibre storage shelf as claimed in any preceding claim, wherein one of the trays carries at least one fibre storage reel for storing lengths of fibre in a coil.

7. An optical fibre storage shelf as claimed in Claim 6, wherein the or each fibre storage reel has coaxial inner and outer circular tracks for holding fibre, with the cylindrical walls of the tracks being interrupted to allow fibre to pass from one track to the other, as well as into and out of the reel.

8. An optical fibre storage shelf as claimed in any preceding claim, wherein the fibre guide means includes a surface upstanding from the plane of the fixed tray to abut a fibre loop from one side and thus to urge the fibre loop to follow a desired path.

9. An optical fibre storage shelf as claimed in Claim 8, wherein the fibre guide means includes fixed guides arranged to hold the fibres in a curved arrangement in one plane.

10. An optical fibre storage shelf substantially as herein described with reference to the accompanying drawings.