Fiber optic closure methods and apparatus

A multiport includes a multiport housing top piece, and a multiport housing bottom piece welded to the housing top piece. Alternatively, a method for fabricating a multiport includes providing a multiport housing top piece, providing a multiport housing bottom piece, and welding the housing top piece to the housing bottom piece. Additionally, a method of fabricating a multiport housing piece includes providing a body, and welding a plurality of connector adapters to the body. Alternatively, an optical fiber connector closure includes a connector housing top piece, a connector housing bottom piece, and a strength seal positioned between the top piece and the bottom piece such that said connector closure has a burst test rating of about 5 to about 125 Pounds per Square Inch (PSI).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to telecommunication line equipment. More particularly, the invention relates to fiber optic closures and methods for fabricating multiports.

2. Technical Background

At least one known optical closure configuration includes a housing top piece and a housing bottom piece, with a sealing gasket there between. The pieces are held against one another, i.e., both pieces are biased toward the gasket with a mechanical fastener such as a screw fastener to provide seal compression. Another known configuration includes a gasket and at least one clip fastener providing a compression force against the gasket. It is desirable to reduce the time and costs associated with the known configurations for sealing and fastening.

SUMMARY OF THE INVENTION

In one aspect, the present invention is directed to an optical fiber connector closure that includes a connector housing top piece, and connector housing bottom piece, and a strength seal positioned between the top piece and the bottom piece such that the connector closure has a burst test rating of about 5 to about 125 Pounds per Square Inch (PSI). The strength seal can be, for example, a weld, and the connector closure can be an adapter closure.

In another aspect, the present invention is directed to a fiber optic connector closure including at least two connector housing pieces welded together.

In another aspect, the present invention is also directed to a method for fabricating a fiber optic connector closure. The method includes providing a fiber optic connector closure housing top piece, providing a fiber optic connector closure housing bottom piece, and welding the housing top piece to the housing bottom piece.

In still another aspect, the present invention is still further directed to a method of fabricating a fiber optic closure connector housing piece. The method includes providing a body and joining, as by welding or fusing, a plurality of connector adapters to the body.

It is to be understood that both the foregoing general description and the following detailed description present exemplary embodiments of the invention, and are intended to provide an overview or framework for understanding the nature and character of the invention as it is claimed, and not for reasons of limitation. The accompanying drawings are included to provide a further understanding of the invention, and are incorporated into and constitute a part of this specification. The drawings illustrate various embodiments of the invention, and together with the detailed description, serve to explain the principles and operations thereof, and are not provided for reasons of limitation.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to several exemplary embodiments of the invention, and examples of which are illustrated in the accompanying drawings. Whenever possible, the same reference numerals will be used throughout the drawings to refer to the same or like parts.

FIG. 1illustrates a device10having a housing12and a housing14which are referred to by way of non-limiting examples as top and bottom pieces, respectively. The device10can be a multiport device or another fiber optic connector housing. The device may include housing or pieces attached to or in addition to housings12and14. Although described and illustrated with reference to a top and lower relationship the benefits of the invention accrue to other housing geometries and therefore the term “housing top piece” refers to one part and the term “housing bottom piece” refers to another part, wherein the parts can be in any geometric relationship. For example, in one embodiment, the housing top piece is below the housing bottom piece, and, in another embodiment, the top and bottom pieces are side by side. Connector housing10includes at least one connector16(such as a port), and, more preferably, it has a plurality of ports16and the closure can take the form of a “multiport” fiber optic terminal or closure attached to at least one cable. Although the fiber optic connector closure of the present invention is illustrated having four ports, it is contemplated that the benefits of the invention accrue to connector closures with any numbers of ports, and the illustration ofFIG. 1is exemplary. Additionally, the terms “port” and “connector adapter” are used interchangeably herein and both refer to an optical fiber interconnection area including a mechanical device designed to align fiber-optic connectors. The connector and adaptor parts can be attached using a strength seal in accordance with the present invention. Additionally, as used herein the term “fiber optic connector closure” refers to fiber optic closures forming a shell and an interior space wherein at least one fiber optic connector is positioned within the interior space or on the shell itself. The connector can be any type of connector such as a plug, a receptacle, a jack, or preferably an adapter. As can be seen in the figures, multiport10is one example of a fiber optic connector closure.

The ports may be in any arrangement, such as two or more rows, side-by-side, or a single row, or in staggered rows and can be located on the tops, sides or edges of the housing piece(s). The ports may be on a flat surface or on an angled surface. Pieces12and14can be of the same material or of different materials. In one embodiment, at least two of the housing pieces are formed of polypropylene. In one embodiment, at least two of the housing pieces are formed of different materials. Suitable materials include plastic such as polypropylene and polyethylene, filled polymers (using talc, glass, or other material), rubber, ceramic, glass, and other materials.

One embodiment preferably includes at least one flexible section in multiport10. In another embodiment, multiport10includes a plurality of flexibly attached sections. The different sections can be attached with a flexible material such as an elastomer or can use mechanical devices that allow flexibility such as hinges. Alternatively, the housings can be fabricated from a highly flexible material. Additionally, several multiports10can be installed in a series on a single cable line with the spacing of the cable lengths between the multiports10allowing for a flexible deployment and non-preterminated fibers can pass a particular multiport10and be terminated down the cable line either at an end of the cable or at another multiport10or other type of fiber optic connector housing.

FIG. 2is a perspective cut away view of multiport10depicting an exemplary embodiment of the invention where the cable ends at closure10, andFIG. 3is a side cut away view of multiport10. Optical fiber20enters an interior space22of multiport10from a cable24and extends to at least one port16. Multport10is preferably sized to define a slack storage space26in an open space28. The slack storage space26can be at any location in the closure. The cable can enter into the housing pieces12or14in a butt configuration with a stub in one end and the drop cables facing the same end. Or it could be a through configuration with a stub in one end, and drop cables out the opposite end.

For example, in one embodiment, to seal housing top piece12and housing bottom piece14together, the strength seal can include a heat soluble resin. The heat soluble resin can be in the form of a thermoplastic cord containing magnetically active particles. The heat soluble resin is placed in groove32, and the top and housing bottom pieces12and14are pressed toward each other. An induced energy then heats the heat soluble material (also referred to herein as a resin) causing the heat soluble material to soften and then re-harden upon a subsequent cooling thereby making a strong seal at the housing interface. Typically, the strength seal (e.g., the cord of thermoplastic) extends entirely around a circumference of the pieces to be welded together; however, in some applications the cord does not extend entirely around the circumference, but just along some of the circumference. The resin can include magnetically active particles and the induced energy can be an RF electromagnetic field which induces eddy currents in the magnetically active pieces. The eddy currents flowing in the magnetically active particles heat the magnetically active particles which cause the heat soluble material to soften and bond with top and housing bottom pieces12and14. The RF field is then turned off, and when the heat soluble material cools off, the heat soluble material hardens, and thus, top and housing bottom pieces12and14are welded together. One exemplary embodiment employs EMABOND™ commercially available from the Ashland Specialty Chemical company of Ohio as the heat soluble material with embedded magnetically active particles.

In one embodiment, connector adapters16are molded into housing top piece12, for example, adapters16can be co-injection molded with the rest of housing top piece12. Alternatively, in another embodiment, connector adapters16are fabricated separately and a strength seal is positioned between adapters16and housing top piece12. For example, and in one embodiment, connector adapters16are fabricated separately from housing top piece12and adapters16are then welded to housing top piece12using the same or similar welding process described above. The closure of the present invention preferably has a burst test rating of about 5 to about 125 Pounds per Square Inch (PSI), more preferably about 5 to about 25 PSI, and most preferably about 5 to about 15 PSI. Also, the closure should withstand multiple freeze-thaw cycles without significant performance issues. For example, connector closures10fabricated as described above are able to withstand temperature cycling of 120 cycles at −40C to +65C over a 30 day period. Additionally, closures10can pass freeze-thaw tests that involve 10 freeze thaw cycles over an 80 day period. After the freeze-thaw tests, multiports10have withstood a water immersion test where multiports10were placed under ten feet of water for seven days and experienced no leakage. At least one connector should be either within the enclosure or positioned in a wall of the closure. Preferably the connector is an adapter. As used herein, the term wall refers to any surface of a closure housing including a top or bottom surface as well as side surfaces. Additionally, it is contemplated that the benefits of the invention accrue to any shaped closure not just the shapes as illustrated. Suitable shapes include ones with square cross-sections, oval cross-sections, circular sections, as well as cross-sections with at least one line of symmetry and cross-sections with no lines of symmetry.

Multiport10can be a pre-terminated closure that allows drop cables to be deployed rapidly in an aerial, pedestal, or below grade settings. The stub end of the cable can be routed aerially, or underground through a duct, or direct buried and spliced into a pedestal, or any other type of closure or rack. Connector adapters are, in one embodiment, positioned on an outside surface of multiport10to allow a craftsperson to easily plug in a drop cable. This avoids the cost and time of entering a closure and splicing fibers. Multiport10can be pre-terminated at a factory. The connector adapters16are welded to housing top piece12, the cable is pre-terminated and connectorized with the resulting pig tails being plugged into the inside side of adapters16. Forming the strength seal at the interface of housing top piece12and housing bottom piece14provides a virtually non-re-enterable closure10. The strength seal, preferably in the form of a weld, eliminates the need for gaskets and mechanical fasteners; however, closure10can include a gasket or mechanical fastener if desired. As used herein the term “strength seal” refers to welds, fused materials (e.g., the use of a glue, melted material, or other adhesive), while providing the herein described burst test performance.

FIG. 4illustrates a method48for fabricating a multiport10. The method includes providing a multiport housing top piece50, providing a multiport housing bottom piece52, and forming a strength seal zone on at least a portion of the interface of the housing top piece50to the housing bottom piece52.

FIG. 5illustrates a method58of fabricating a multiport housing piece. The piece could be the housing top piece or the housing bottom piece. The method includes providing a body60and forming a strength seal zone between a plurality of connector adapters and the body62. In one embodiment the strength seal zone is a weld comprising a thermoplastic cord as described above. The body can be fabricated from any of the materials listed above.

FIGS. 6 and 7illustrate in detail that housing pieces12and14define a strength seal40at an interface area. Housing strength seal40includes a strength member30that mates with a seal area32on housing bottom piece14. In one embodiment, a seal zone34welds or fuses housing top piece12and housing bottom piece14together. A tongue70extends at least partially into groove32. In one embodiment, groove32defines a space wherein seal zone34occupies between 5 and 20 percent of the space so defined. At a top portion of tongue70is a rounded shoulder portion72that advantageously acts as a crack reduction member and reduces stress cracking of tongue70. Portion72has a radius which is scaled to the tongue geometry. Additionally, tongue70includes a stop portion74that limits the insertion travel of tongue70into groove32. Stop portion74is useful in that it maintains sufficient space for the thermoplastic cord to spread when heated and not to be pushed out of groove32while pressure is maintained of top housing12and bottom housing14against each other during the welding process.

It will be apparent to those skilled in the art that various modifications and variations can be made to the present invention without departing from the spirit and scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents. For example, the flexible closure can include components used as couplers, splitters, filters, furcation tubes or other optical components. Additionally, a multi-fiber connector can be in the end wall for plugging in another distribution cable.