OPTICAL FIBER SPLICE HOLDER AND STRAIN RELIEF

Abstract: A holder (30) for jacketed fiber optic cable (26) or ribbon cable (28) having channels (32) extending along a top surface (34), with constrictions (42) to hold jacketed fiber optic cable (26) therein upon insertion with nondeforming strain relief. Protrusions (40) between the channels (32) include narrow slots (44) thereinto to hold ribbon cable (28) therein with nondeforming strain relief. A splice holder (24) having first channels (70) having upper and lower portions (80, 82) separated by a constriction (76) with each portion adapted to hold a respective single-fiber splice coupling (84). Second channels (90) have a large diameter adapted to hold a multi-fiber mass fusion splice coupling (94) used with ribbon cable. Both the first and second channels (70, 90) having constrictions along their entrances of less width than a splice coupling (84, 94) to be inserted thereinto. Splice holder (24) may be adhered to a bottom wall (14) of a splice tray (10).

Description: OPTICAL FIBER SPLICE HOLDER AND STRAIN RELIEF The present invention relates to the field of optical fiber interconnection and more particularly to strain relief members and holders for optical fiber cable. In multiple fiber interconnection arrangements, a plurality of pairs of associated optical fibers are to be interconnected and such interconnections must thereafter be held securely and carefully, usually in an organizer tray or cassette within a larger enclosure or cabinet, and usually in an array of such trays or cassettes. Such trays must also hold generous portions of the fibers adjacent the interconnections, or splices, to permit splice repair without requiring cable replacement. Preferably the trays or cassettes also provide for securing jacketed portions of the cables containing one or more of the optical fibers, at ends of the trays. The splice connections comprise fusion of the ends or end lengths of the associated optical fibers, or adhesive bonding, or precision clamping, and the thus-fused fiber ends are preferably maintained within a protective sleeve or adapter to maintain the precision alignment of the fibers and provide a level of physical protection and strain relief to the coupling. One conventional method for securing optical fiber cables at ends of organizer trays has been to utilize cable ties that extend through holes in the bottom wall of a tray at each end and are snapped overtop of respective jacketed cable portions, or to utilize cable clamps in similar fashion. Within the tray the optical fibers are broken out from the jacket for ends of the optical fibers to be spliced or coupled, with such splice connections to be maintained within grooved holders centrally located between the tray ends or cable exits. It is desired to provide a strain relief member at cable exits from a tray or organizer or cassette, that provides sufficient clamping of jacketed portions of fiber optic cables to relieve strain on the splice connection or coupling, without compressing or otherwise deforming the optical fiber therewithin. It is desired to provide a holder for the array of splice connections of a plurality of pairs of associated fibers. It is also desired to provide a strain relief member for clamping of multifiber fiber optic ribbon cable to define strain relief therefor. The invention comprises a holder for fiber optic members with a member of resilient material including an array of channels to receive a jacketed fiber optic cable. The channels are defined by protrusions therebetween. At least one of the protrusions has a narrow width slot extending parallel to the channels. The slot being complementary to a thickness of a fiber optic ribbon cable and having a depth sufficient to receive the ribbon cable thereinto. The invention further comprises a holder for fiber optic members with a member of resilient material including an array of channels. At least one of the channels has a depth equivalent to twice the diameter of a single fiber splice coupling and has a first constriction along a top surface of the channel. The channels have a second constriction along sides of the channel midway from the top surface and a bottom of the channel defining upper and lower channel portion. An embodiment of the present invention will now be described by way of example with reference to the accompanying drawings. FIGURE 1 is an isometric view of a splice tray having cable strain relief members of the present invention at ends thereof and a splice holder centrally disposed therebetween; FIGURE 2 is an isometric view of the splice holder of FIG. 1, with a representative single-fiber jacketed cable and a representative ribbon cable held therein; FIGURES 3 and 4 are plan and elevation views of the splice holder; FIGURE 5 is an enlarged cross-section view of FIG. 3 taken along lines 5-5 thereof and showing a ribbon- receiving slot and a cable-receiving channel at a cable tie aperture; and FIGURE 6 is an enlarged view of an end portion of FIG. 4. A splice tray or organizer 10 includes a tray body 12 having a bottom wall 14, opposed ends 16,18 and opposed side walls 20,22, as well as a preferably an optionally transparent cover member (not shown) that is securable to tray body 12. A splice holder 24 is affixed to bottom wall 14 centrally positioned between ends 16,18 within which splice connections of pairs of associated optical fibers of single-fiber cables, or splice connections of arrays of fibers of associated ribbon cables may be positioned. Tray 10 provides substantial fiber-holding space between the ends for generous loops of discrete fibers after being broken out from jacketed cables and ribbon cable to be disposed therein that are preferably covered by the protective lid or cover member placed thereover and affixed to tray body 12. Cable strain relief holders 30 are affixed to tray body 12 at respective ends 16,18, such as by use of adhesive or optionally by fasteners. Strain relief holder 30 includes a plurality of generally parallel elongate channels 32 formed into and along top surface 34 extending between first and second ends 36,38, with elongate protrusions 40 positioned between adjacent channels 32. Channels 32 are dimensioned to receive thereinto, if desired, jacketed portions of fiber optic cables 26 (as shown in FIG. 2) that have for example diameters of 3 mm, and each is undercut to form retention ledges 42 near top surface 34 defining therebetween a constriction less wide than the cable that will hold a jacketed cable 26 in position once inserted. Each protrusion 40 preferably has a narrow slot 44 formed thereinto from top surface 34, with narrow slot 44 being dimensioned to approximately equal the thickness of a ribbon cable to receive a ribbon cable 28 thereinto. Narrow slot 44 is also of appropriate width to receive thereinto a buffered portion of a single fiber after being broken out from the jacket of a cable 26, if desired. Preferably the entrance to each slot 44 includes chamfers 46 defining a lead-in facilitating insertion of a ribbon cable thereinto. Slots 44 also can assist in insertion of jacketed cables 26 into channels 32 by allowing upper portions of protrusions 40 to be flexed outwardly when a cable 26 is urged into the slightly narrower entrance to a channel 32 above retention ledges 42. Strain relief holder 30 may also be provided with cable tie apertures 50,52 that are formed to be aligned with corresponding apertures (not shown) in the bottom wall 14 of splice tray 10, permitting mounting of conventional cable ties to the splice tray to supplement the strain relief characteristics of the strain relief holder, if desired. Cable tie apertures 50 are shown intersecting each channel 32 and are to be used when holder 30 is to be used with ribbon cable that utilizes slots 44, while cable tie apertures 52 are shown intersecting slots 44 that are to be used when holder 30 is to be used with jacketed single fiber cable. It can be seen that strain relief holders 30 may be utilized within the splice tray if desired, positioned on both sides of a splice coupler site to hold adjacent portions of buffered fiber or ribbon cable. Similarly, strain relief holders may be utilized independently of a splice tray per se, for similar purposes, with the bottom surface of the bottom member affixed to a surface such as by adhesive, double sided tape and peelable transfer paper, or other fasteners. Strain relief holder 30 may be made for example of a resilient material such as an elastomeric material like, for example, SARLINK polypropylene based elastomer, Part No. 3170 or 3160 or 9760 sold by DSM Thermoplastic Elastomers Inc., Leominster, MA, and may be extruded rather than individually molded since holder 30 generally has continuous cross-sections therealong, with cable tie apertures 50,52 being formable by simple secondary operations. The strain relief member of the present invention may be utilized in pairs, one adjacent each side of the splice couplings near the center of a splice tray if desired. The present invention may also be used independently of a splice tray if desired by simply being secured to a selected surface in a desired orientation to receive and hold fiber optic members such as jacketed fiber optic cable, discrete buffered optical fiber or ribbon cable. Variations and modifications may occur to others that are within the spirit of the invention and the scope of the claims. FIGS. 7 to 9 illustrate a first embodiment of the splice holder 24 of the present invention, a generally thick planar member of elastomeric material having opposed ends 60,62 and opposed side edges 64,66 dimensioned to.be placed into splice tray 10 between side walls 20,22 and centrally disposed between tray ends (FIG. 1) . Splice holder 24 may be easily mounted onto bottom wall 14 of splice tray 10 such as by adhesive or cement, or fasteners, or double sided tape and also peelable transfer paper. A centrally located aperture 68 is utilized to permit receipt of a vertical rod therethrough for stacking of several splice trays. An array of first channels 70 is-defined into top surface 72 of holder 24 shown in two regions adjacent side edges 64,66. Several second channels 90 are shown between the two first channel regions and the central region 92 containing aperture 68. Each second channel 90 is generally cylindrical, having a depth and diameter equivalent to the outer diameter of a multi-fiber mass fusion splice coupling 94 such as is used with ribbon cable 28. Mass fusion splice couplings very similar to coupling 94 may also be used with a plurality of discrete buffered fibers not in ribbon cable form, but that are preferably bonded to each other adjacent and outwardly from the ends of the mass fusion coupling. A constriction 98 is defined at the entrance along top surface 72 to hold mass fusion splice coupling 94 therein upon insertion thereinto and therealong. Such fusion splice couplings may be formed such as by use of fiber holders applied by a FITEL Optical Fiber Fusion - 6 - UTE SHEET. RULE 26 Splicer S198A manufactured by Furukawa Electric and sold by JTS FITEL Inc. of Ottawa, Canada. Each first channel 70 has a first constriction 74 defined at the entrance along top surface 72, and each first channel 70 is shown to include a second constriction 76 midway to channel bottom 78 to create upper and lower portions 80, 82 each having a general dimension about equal to the diameter of a single-fiber fusion splice coupling 84 used with single fibers 26. Thereby, each first channel 70 can receive and hold two single-fiber splice couplings 84 therein, economizing on space to increase the density of splice couplings on the splice tray. A pair of narrow width slots 96 are shown adjacent central aperture 68 in central region 92, that are used for providing deflectability of the inside walls of the large channels 90 adjacent central region 92. Each splice holder 24 may be made for example of elastomeric material such as SARLINK polypropylene based elastomer, Part No. 3170 or 3160 or 9760 all sold by DSM Thermoplastic Elastomers Inc., Leominster, MA, and may be extruded rather than individually molded since holder 24 generally has a continuous cross-section therealong, with central aperture 68 being formable by a simple secondary operation. FIG. 10 illustrates a second embodiment of the present invention of a splice holder 100. A central splice holding portion 102 is shown to have a top surface 104 having formed thereinto generally first channels 106 for single-fiber splice couplings, and second channels 108 for mass fusion splice couplings and may be identical to first and second channels 70,90 of splice holder 24 as shown in FIGS. 7 to 9. A thin, flat base portion 110 extends from opposed first and second splice holding ends 112,114 to strain relief regions 116 spaced from first and second ends 112,114. Each strain relief region 116 includes an array of narrow width slots 118,120 extending into top surface 104 and aligned with first channels 106 and second channels 108 respectively. The width of each slot 118 is equivalent to the diameter of a single buffered fiber 26, and the width of each slot 120 is equivalent to the thickness of ribbon cable 28. Strain relief region 116 thus at least holds a portion of each fiber 26 and ribbon cable 28 at a selected distance from the splice holding central portion 102 and thus serves to isolate the splice couplings from stress resulting from different lateral directions assumed by the portions of the fibers and cables extending from the splice holder. The splice holder of the present invention may be utilized independently of a splice tray if desired by simply being secured to a selected surface in a desired orientation to receive and hold fiber optic couplings such as of discrete or single fiber optic cable or of ribbon cable. Variations and modifications may occur to others that are within the spirit of the invention and the scope of the claims.

Claims: WHAT IS CLAIMED IS: 1. A holder for fiber optic members comprising a member of resilient material including an array of channels (32) to receive a jacketed fiber optic cable (26), the channels being defined by protrusions (40) therebetween, characterized in that at least one of the protrusions (40) having a narrow width slot (44) extending parallel to the channels (32), the slot (44) being complementary to a thickness of a fiber optic ribbon cable (28) and having a depth sufficient to receive the ribbon cable thereinto. 2. A holder as set forth in claim 1 wherein said slots include chamfered (46) entrances defining lead-ins facilitating ribbon cable insertion. 3. A holder as set forth in claim 1 wherein said resilient material is elastomeric material. 4. A holder as set forth in claim 3 wherein said elastomeric material is a polypropylene based elastomer. 5. The holder as set forth in claims 1-3, wherein the member of resilient material is installed in a fiber optic splice tray (10) and provides strain relief for the cable installed therein. 6. A holder for fiber optic members comprising a member (24) of resilient material including an array of channels (70) at least one of the channels (70) having a depth equivalent to twice the diameter of a single fiber splice coupling and having a first constriction (74) along a top surface (72) of the channel, characterized in that channels (70) have a second constriction (76) along sides of the channel midway from the top surface and a bottom of the channel defining upper and lower channel portions (80,82). 7. A splice holder as set forth in claim 6 wherein said member (24) includes at least one second channel (90) defined into said top surface, each said second channel (90) having a depth and width equivalent to the diameter of a mass fusion splice coupling, for receipt thereinto and holding of a mass fusion splice coupling. 8. The splice holder as set forth in claims 6-7 wherein said resilient material is an elastomer. 9. The splice holder as set forth in claim 8 wherein said elastomeric material is a polypropylene based elastomer. 10. The splice holder as set forth in claim 7 wherein a strain relief portion (30) has a plurality of slots (32) into said top surface (34) aligned with said first and second channels for receiving thereinto said single fibers and said ribbon cables extending from said single-fiber splice couplings and said mass fusion splice couplings, respectively.

Inventors: KEENER SCOTT ALAN, RADLIFF DAVID RAY, STOUGH ROBERT E, KEENER, SCOTT, ALAN, RADLIFF, DAVID, RAY, STOUGH, ROBERT, E.
Applicants: WHITAKER CORP, THE WHITAKER CORPORATION
Application year: 1996
Main classification: G02B6
IPC codes: G02B6