RETAINER FOR PACKAGED OPTICAL FIBER SPLICES AND ORGANISING TRAY UTILISING SUCH RETAINERS

Abstract: A packaged optical fiber splice is held in a retainer (10) formed by two pairs of cantilever members (13) having inward­ ly facing ribs at their top edges. The members of a pair are spaced so that after pushing a packaged splice between the ribs, deforming the members slightly, the packaged splice is freely positioned between the cantilever members which are at least substantially stress free. The splice is retained by the ribs. A slot (15) in the base of the retainer provides a seating for the lower edge of the splice and restrains the splice against longitudinal movement. A plurality of retainers are provided in an organizing tray.

Description: RETAINER FOR PACKAGED OPTICAL FIBER SPLICES AND ORGANISING TRAY UTILISING SUCH RETAINERS This invention-relates .t? a retainer for holding a packaged optical fiber splice and to at arrangement comprising a tray, or a plurality of trays, having tetainers. Optical fiber cables require splicing of the individual fibers at the junction of cables. The fibers are spliced, typically by fusion splicing, and the splice protected, and strengthened, by enclosing or packaging in protection members. The protection members are then positioned in a retainer in an organizing tray. The tray provides room for a length of fiber either side of the splice which provides some spare length. This is bent round in the tray and the dimensions of the tray are such that the radius of the bend is large enough to prevent undue losses in the fiber. A retainer should hold a splice in position without producing any stress on the splice. Once positioned, a splice is normally in that position for a long time and the retainer should hold the splice without being affected by climatic conditions. It has been found that molded plastic retainers which are stressed by the insertion of a protected splice, the stress remaining as long as the splice is in position, suffer from relaxation during use. An attempt to mold an organizer tray using a stiff grade of plastic with the retainer members molded integrally but using a soft, flexible, grade of plastic, while overcoming the problem of relaxation, is extremely difficult to manufacture, and is expensive. The present invention provides a retainer which is molded as a separate unit and is then attached to a tray. This can be by bonding or by snap action, for example. The retainer has cantilever members extending up from a base, forming two pairs of members spaced laterally. The members have inwardly extending ribs at their top edges. An elongate slot extends at least partly through the base between the cantilever members. A packaged splice is pushed down between the pairs of cantilever members and rests in the slot, below the ribs. Thus, once the splice is in position, the cantilever members are unstressed. Lengthwise movement of the splice is prevented by the ends of the slot in the base. The invention will be readily understood by the following description of certain embodiments by way of example, in conjunction with the accompanying drawings, in which: Figure 1 is a top plan view of the center part of a tray, with a multiple retainer member in position and fiber splices in the individual retainers; Figure 2 is a cross-section of the retainer member only on the line II-II of Figure 1, to a larger scale with splice omitted; Figures 3 and 4 are cross-sections through an individual retainer, without a packaged splice and with a packaged splice respectively; Figure 5 is a perspective view of a splice in the process of being packaged or protected; Figure 6 is a cross-section through a protected splice; Figure 7 is a cross-section of a tray, on the line VII-VII of Figure 1; Figure 8 is a side view of a tray; ; Figure 9 is a perspective view of a tray, with retainers, illustrating the entry of fiber cables to a tray, and exit from a tray. Illustrated in Figure 1 is a retainer member, indicated generally at 10, having a plurality of retainers, indicated generally at 11. In this figure, the member 10 is seen attached to an organizer tray 12. Each retainer has two pairs of cantilever members 13 spaced apart across the member, in the direction of the length of the tray. In Figure 1, a packaged splice, indicated at 14, is positioned in several retainers. The form of the members 13, and the arrangement of retainers, is seen more clearly in Figures 2, 3 and 4. In Figure 2 there is shown the pairs of members 13, and one particular way by which the retainer member can be attached to a tray. From a bottom web 15 of the retainer member 10 extend projections 16 which pass through holes in the base of the tray. These projections can be rivetted over to retain the retainer member in position. Alternatively they can be split, with outwardly extending ribs at the 'bottom, to give a snap assembly. As readily seen in Figure 3, each cantilever member 13 has an inwardly projecting rib 17 near its top edge, with an inwardly and downwardly inclined surface 18 extending from the top edge to the rib. A slot 19 extends through the web 15 between the members 13, the slot extending a short distance beyond the pairs of members 13, at each end, as seen in Figure 1. Figure 4 illustrates the arrangement of a packaged splice 14 situated in a retainer. The packaged splice is of the form as described in U.S. Patent 4,254,865 issued March 10, 1981 to the present assignee and as illustrated in Figures 5 and 6. The packaged splice is inserted into a retainer by pushing it down between the pairs of cantilever members 13. The members deflect apart as the lower edge of the packaged splice 14 push against surfaces 18. Once the packaged splice has moved fully into the retainer, the top edge is below the ribs 17 and the members 13 snap over the packaged splice. The members 13 are thus not under stress. The splice sits in the slot 19 and is therefore restrained from lengthwise movement. With the retainer member fitted to a tray, the packaged splice rests on the base of the tray. However, if retainers are made as individual units, or even as multiple units, without having a tray base or other surface under them, the slot 19 can be arranged to extend only part way through the web 15. This arrangement can also be used with trays. The splice protecting package, in one form, is illustrated in Figures 5 and 6. It comprises two flat members 25 hingedly connected by a layer of adhesive material 26. The members 25 have shallow semi-circular grooves 27 extending in from each end. A fusion spliced fiber 28 is positioned on one member, the coated portions of the fused fiber, indicated at 29, positioned over the grooves 27. The members are then hinged or folded together, gripping the fused fibers between them, as seen in Figure 6. This packaging or protection is described in more detail in the above mentioned patent. One form of tray is illustrated in cross-section in Figure 7, and in side view in Figure 8. The tray has a base 30 with an upstanding web 31 adjacent each side edge, the webs having inwardly extending ribs 32. Extending downward from the side edges are further webs 33, and also downwardly extending ribs 34 extend parallel to and spaced a short distance in from webs 33. Near each end of the tray, at each side, a slot 35 extends through the rib 32 and part way down web 31. Below each slot 35 there is an aperture 36 through the web 31. The use of these will be explained in conjunction with Figure 9. The webs 33 extend only for part of the length of the tray, stopping short of the ends. However the ribs 34 extend the full length of the tray. However these particular features can vary to suit requirements. In a single tray usage webs 37 and ribs 34 may not be present. Figure 9 illustrates a tray 12, with a multiple unit retainer 10, and with optical fiber cables entering and leaving, the cables indentified at 40 entering at one end, and at 41 at the other end. The cables will contain several fibers and the cable casing is removed at the end to expose a length of each fiber. The ends of the casing are positioned at the ends of the tray, against the webs 31 under the ribs 32. Ties 42 pass through the aperture 36 in webs 31, round the cables and through the slots 35. If necessary a sleeve 43 can be positioned on a cable to assist in the gripping of the cable by the tie. The ties 42 act as strain reliefs and prevent the cables and fibers from being pulled out of the tray. Trays can be mounted, one above the other. The inwardly extending ribs 32 of a lower tray snap into position above convex formations 45 on the outer surfaces of the ribs 34. A cover, having ribs similar to ribs 34 on a tray, can be snapped into position on a top tray. Several trays, stacked one on top of another, can be positioned in an enclosure or housing, as described in U.S. Patent 4,359,262, issued November 16, 1982, to the present assignee. The top surface of the tray base can be ribbed to make it easy to pick up fibers resting on the tray base. The retainers are offset or staggered, in the retainer member, as illustrated in Figure 1, to make it easier to grip tabs 50 attached to the packaged splices, the tabs identifying splices.

Claims: Claims: 1. A retainer for a packaged optical fiber splice, characterized by a bottom web 15; two pairs of cantilever members 13 spaced apart along the web and extending up therefrom, the members of a pair spaced apart a distance slightly larger than the thickness of a packaged splice, the pairs spaced a distance less than the length of the packaged splice; an inwardly extending rib 17 at an upper part of each cantilever member 13, the inner surfaces of the ribs spaced apart a distance less than the thickness of the packaged splice; a slot 19 in said bottom web, extending between the cantilever members 13 for a distance substantially equal to the length of the packaged splice; the ribs 17 spaced from the bottom of the slot 19 a distance at least equal to the height of the packaged splice; whereby a packaged splice 14 can be pushed down between the cantilever members 13 into the slot 19 and restrained from longitudinal movement, and the ribs 17 engaging over the packaged splice and the cantilever members 13 being substantially free of stress. 2. A retainer member for holding a plurality of packaged optical fiber splices characterized by a plurality of retainers 11 as claimed in claim 1, the bottom web 15 being unitary and common to all of the retainers. 3. A retainer member as claimed in claim 2 characterized by each retainer 11 being offset laterally relative to the immediately adjacent retainer 11, whereby the retainers form a zig-zag arrangement across said bottom web 15. 4. A retainer member as claimed in claim 2 characterized by an organizing tray 12 having a base 30, the bottom web 15 attached to the base of the organizing tray. 5. A retainer member as claimed in claim 2 characterized by means 16 extending from the bottom web 15 for attachment to a support member 12. 6. A retainer member as claimed in claim 4 characterized by the bottom web 15 being bonded to the base 30 of the organizing tray 12. 7. A retainer member as claimed in claim 4 characterized by the bottom web 15 including downwardly extending projections 16, the projections extending through the base 30 of the tray 12 to attach the bottom web to the tray. 8. A retainer member as claimed in claim 4 characterized by the slots 19 extending through the bottom web 15, an upper surface of the base 30 of the tray 12 defining the base of the slots. 9. A retainer member as claimed in claim 4 characterized by the tray 12 including an upstanding web 31 adjacent to each side edge of the base and extending lengthwise of the base 30, and an inwardly extending rib 32 along the upper edge of each upstanding web 31. 10. A retainer member as claimed in claim 9 characterized by the tray 12 including a web 33 extending downward at each side edge of the base 30 and a rib 34 extending downward from each side edge of the base 30 spaced inward from the downwardly extending webs 33, whereby the upstanding webs 31 and inwardly extending ribs 32 of a lower tray 12 can be positioned between the downwardly extending webs 33 and downwardly extending ribs 33 of an upper tray 12.

Inventors: BARBER, ROBERT JOHN, CHARLEBOIS, LEONARD JOSEPH, SCOTT, JAMES RONALD
Applicants: NORTHERN TELECOM LIMITED
Application year: 1984
Main classification: G02B6
IPC codes: G02B6