WO1990005930A1

WO1990005930A1 - Optical fiber splice tray

Info

Publication number: WO1990005930A1
Application number: PCT/US1989/005153
Authority: WO
Inventors: Daniel Gronvall
Original assignee: Raychem Corporation
Priority date: 1988-11-17
Filing date: 1989-11-17
Publication date: 1990-05-31
Also published as: AU4648789A; KR900702393A; CA2003216A1

Abstract

An optical fiber splice tray (40a, 40b) capable of permitting the close packing of a plurality of optical fibers while fitting within a substantially standard pedestal closure (10) is described. The splice tray (40a, 40b) further provides installer-ready access to the optical fibers while maintaining the optical fiber cables at a radius greater than the minimum bend radius of the optical fibers so as to minimize optical losses.

Description

OPTICAL FIBER SPLICE TRAY

Field of the Invention

The invention relates to an optical fiber splice tray. More specifically, the invention relates to an optical fiber splice tray suitable for insertion into a compact optical fiber pedestal container. In particular, the inven¬ tion relates to a fioer optical splice tray capable of per¬ mitting easy access to demateable optical fibers contained within an optical fiber pedestal container.

Background of the Invention

As optical fibers move out of the laboratory and into widespread commercial use, organizers for multiple optical fiber splices are required to introduce individual homes into the main transmission system. Unlike copper wires which are used in the vast majority of home hook-ups, optical fibers lose their effectiveness when bent in a radius smaller than the minimum bend radius. Although the minimum bend radius varies from fiber to fiber, a mimimum bend radius for a given fioer must be taken into account when packaging it in asso¬ ciation with other fibers.

Optical fibers normally fit into a splice tray which carries a plurality of fibers. Raychem markets an optical fiber splice tray under the name Fosc 30/60™ closure system. The splice tray permits a plurality of fibers to be organized on a plurality of splice trays and sealed against moisture and corrosion within either a recoverable sleeve or through the use of a mechanical ring closure system. Although this system functions extremely well, the number of separable intercon¬ nected optical fibers it can accommodate is limited.

Still other systems and connectors are taught in U.S. Applications 721,527 filed April 9, 1985; U.S. 110,051 filed October 13, 1987 and U.S. 178,115 filed April 6, 1988. Each of these Applications are incorporated herein by reference for all purposes.

Permanent optical fiber splices, i.e., welded or glued splices, are suitable for environments where the drop optical fiber is not apt to be disturbed or injured. In resi¬ dential or commercial applications where the drop optical fiber may be broken by excavation or otherwise damaged, the aoility to reenter the splice closure and substitute an unda¬ maged optical fiber cable would be highly desirable. Another desirable feature would include a provision for the quick con¬ nection and disconnection of the drop optical fiber into the system. It would also be desirable to be able to handle a plurality of fibers in a compact arrangement capable of fitting within a closure having substantially similar dimen¬ sions to current closures already in commercial use for copper drop wires or optical fibers.

Typical demateable optical fiber connectors appart from fusion splices, require several inches of space on either side of the actual fiber coupling to avoid Dending the fiber beyond the minimum bending radius. Standard closures of dimensions approximately equal to pedestal closures for copper wires, cannot arrange many connections along the axis perpen¬ dicular to the longitudinal axis of the closure and still maintain a-.minimum Dend radius sufficient to preclude unaccep- tably high losses of light leaking out through the bent fiber. Thus, it would be highly desirable to have a design which per¬ mits the optical fibers to be contained within a closure with a crosssection just slightly larger than the minimum bend radius of the fiber. It would be desirable to have an optical fiber layout that provides for easy access to the optical fiber connections and permits a neat organization of the fioers. Summary of the Invention

The invention provides for the previous recited desiraole features and other benefits which are readily apparent to the ordinary skilled artisan. More specifically, the invention provides for plurality of demateable fibers within a housing which is substantially identical to housings for copper wires. The optical fiber splice tray of the inven¬ tion permits the close arrangement of, and the easy access to, optical fibers with dematable connectors within a minimum/ limited space such as found within standard pedestal closures is described. The splice tray further provides optical fiber organization and maintains optical fiber bend radii greater then, but close to, the minimum bend radii of the type of optical fioer and signal frequency used so as to minimize transmission losses and maximize the effective use of space.

Brief Description of the Figures

Fig 1 illustrates an exploded view of a pedestal clo¬ sure including the optical fiber splice tray of the present invention.

Fig 2 illustrates a top plan view of the optical fiber splice tray of the present invention.

Detailed Description of the Invention

The invention will be more clearly illustrated by referring to the attached Figures. Fig 1 illustrates the optical fiber closure system of the invention as 100. The closure system includes pedestal cap 10 capable of mating to a base member 20 and sealed thereto with a clamp and gasket system 30. Splice trays 40a and 40b hold a plurality of opti¬ cal fibers together or a virgin unspliced fiber for passing through the pedestal base member 10 which do not form part of the drop system. • The optical fiber splice tray of the present invention 50 is hingeably attached to the- base member 20, i.e., liftable as illustrated by the arrow, to provide more ready access to the spliced fibers. Alternatively, the tray 50 can be fixedly mounted, removeably attached, and the like. The case member 20 can also iclude a plurality of splice trays 5u. The benefits of the splice tray will be more apparent by referring to Fig 2.

In Fig 2, the incoming optical fibers on splice tray 50 are illustrated as 400a to 400e. The incoming optical fioers 400a through 400e bend, with an angle greater than the minimum bend radius within the tray, at an oblique angle to the longitudinal length of the tray. Preferably the angle is aoout a 45° angle with respect to a- perpendicular bisecting the longitudinal axis. Assuming the base portion 50a of the tray 50 connected to the base member 20 forms a straight edge, then this base portion 50a and the longitudional edges 50b and 50c of the tray 50 form the x-y axis from which to measure the angle of the connectors 56 and 58. The connectors 56 and 58 can be located at an angle wnich is less than or greater than about 45°, i.e., on the order of from about 15° to about 85°, preferably aoout 30° to aoout 60°C although the most pre- xeraole angle of about 45° ensures maximum close packing. The optical fiber connectors 56 and 58 are held at the desired angle by suitable positioning means for positioning the con¬ nectors sucn as clips, or passageways formed between the underside of the bridge member 52 and the base portion of the splice tray 50.

The ends of the fibers 400a througn 400e contain demateable connectors 56a through 56e. The drop wire optical fiøers 500a to 500e are connected through the connectors 58a to 58e to the connectors 56a through 56e at an oblique angle, as described, with the drop wire optical fibers 500a through 500e positioned to form substantially a figure-8 shape. In forming the figure-8 shape the optical ficers 500a throgh 500e bending around and over the optical connectors 56 and 58 by a oridge member 52.

The bridge member 52 provides a track for the outgoing drop optical fibers with all bends being compactly arranged not to be less than the minimum bend radius of the optical fiber. The optical fibers are held in place by flexible tabs, clamps, and the like, 54a to 54f. Access areas 60a and 60b permit the positioning of the installers fingeers on the opposing sides and/or portions, of the connectors 56a to 56e and 58a to 58e, respectively, thus allowing the installer to connect or disconnect 56a through 56e from 58a through 58e. Preferably the areas 60a and 60b are voids i.e., cut-outs, in the ϋase 50.

The oolique angle of the fibers relative to the longitudinal axis permits a substantially higher packing of optical fibers then mounting them perpendicular to the longi¬ tudinal axis. In addition, the angle permits a narrower housing to be utilized. The bridge member 52 organizes the fibers and ensures that the optical fibers will not be pinched by overlapping the edges of the tray, i.e., impede access to the cut-outs 6ϋa and 60b. Preferably the bridge member is "U" shape, i.e., the member 52 has guiding rails to retain the fibers within the bridge memoer. Although any containing shape is suitable.

Having descrioed the preferred embodiments, obvious modifications are contemplated to be within the scope of the invention.' For example, the trunk fibers 400a to 400e could enter through the bridge member 52 and the drop wires 500a to 500e could exit where the presently positioned entrance fibers wires 400a to 4ϋϋe are located. Finally, the bridge member 52 can go under the optical connectors and the figure-8 shape can be square or 9-shaped if the incoming and* outgoing fibers are parallel and tne bends are sized not to be sharper than the minimum bend radius of the optical fiber. The tray can also be used for copper wires and the like.

Claims

I Claim:

1. An optical fiber splice tray comprising:

a base;

at least one bridge member substantially centrally located and positioned in a region of the base to provide access to optical fibers splices contained between the bridge member and the base; and

positioning means for positioning optical fiber con¬ nectors at an oblique angle relative to the longitu¬ dinal axis of the optical fiber splice tray and between the base and the bridge member.

2. The splice tray according to claim 1 wherein the base further provides for access ports to readily permit the connecting/disconnecting of the optical fibers.

3. The splice tray according to claim 2 wherein the

—- incoming and exiting optical fibers are configured to exhibit figure-8 pattern with the optical fibers being spaced apart and substantially parallel at an end of the base.

4. The splice tray according to claim 3 wherein the tray is hingably mounted to a base support, said base sup¬ port capable of mating to a pedestal cap with a mechanical or recoverable seal between the cap and the base support.

5. The-splice tray according to claim 4 wherein the optical fiber connectors are located at about 45° angle relative to the longitudinal axis of the splice tray.

6. The splice tray according to claim 2 wherein incoming and exiting optical fibers are parallel and adjacent at the base member in the shape of a figure 9.

7. The splice tray according to claim 1 wherein the optical fibers are located at an angle that is be¬ tween about 15° to about 85° relative to the longitu¬ dinal axis of the splice tray.

8. The apparatus according to claim 7 wherein the clo¬ sure contains a plurality of optical fibers splice trays.

9. A method of organizing optical fibers within a splice tray comprising:

positioning optical fiber connectors on a tray at an oblique angle relative to the longitudinal, axis of the tray;

connecting optical fibers thereto; and

routing the connected optical fibers in a figure-8 pattern around the connected optical fibers.

10. That method according to claim 8 further comprising accessing optical fiber connectors above and below the optical fiber connectors.