Optical waveguides – Optical transmission cable – Ribbon cable
Reexamination Certificate
1999-12-21
2001-09-25
Spyrou, Cassandra (Department: 2872)
Optical waveguides
Optical transmission cable
Ribbon cable
C385S109000, C385S113000, C385S112000
Reexamination Certificate
active
06295401
ABSTRACT:
The present invention relates to optical fiber cables, and, more particularly, to optical fiber cables having at least one optical fiber ribbon therein.
Conventional fiber optic cables include optical fibers that conduct light in the transmission of voice, video, and data information. Optical cables have the advantages of large bandwidth and low power loss. Typical applications for optical cables include fiber-to-the-curb (FTTC), fiber-to-the-home (FTTH), fiber-to-the-desk (FTTD), plenum, riser, and local area networks (LANs). In a premises environment, optical zipcord cables can be used to interconnect operating equipment, for example, computers, modems, and telephones. For example, Operating Equipment Manufacturers (OEMs) may require low-cost, optical interconnect cables for use in transceiver applications.
Transceiver applications require sufficient space between fibers to avoid electrical crosstalk. Opto-electrical and electro-optical transducer components, for example, are used in such systems to interface between electrical and optical modes of signal transmission. Electrical systems, however, may experience crosstalk between the signal wires thereof. This type of electrical crosstalk occurs due to electromagnetic fields surrounding the transmitting wires. The electromagnetic fields of one circuit induce currents and electromotive forces in adjacent circuits. For example, electrical crosstalk affecting a telephone line may result in the undesired mixing of caller conversations. Spacing the electrical wires of different circuits tends to reduce electrical crosstalk. On the other hand, because optical-based systems use confined light as the information carrying medium rather than electricity, optical-based systems are not as susceptible to crosstalk and therefore do not require a significant crosstalk type spacing between the optical fibers.
Opto-electrical and electro-optical transducers generally require electrical wires to be spaced apart sufficiently enough to avoid crosstalk. For convenience, respective ends of optical fibers in single fiber cables are connected to such transducers by placing them in housings comprising spaced-apart, fiber receiving apertures. Another method is to connectorize a two-fiber optical ribbon with a 250 &mgr;m spacing between the fibers. Such conventional methods can be relatively expensive in respect of installation and material costs because two fibers must be individually connectorized. Another method is to connectorize a 2-fiber optical ribbon with a 750 &mgr;m spacing to a multi-fiber connector, as described in U.S. Pat. No. 5,966,489 which is incorporated by reference herein. The multi-fiber ferrule separates the fibers at a 750 &mgr;m spacing.
SUMMARY OF THE INVENTION
One aspect of the present invention is a fiber optic cable comprising at least one optical sub-unit with a jacket and an optical fiber ribbon therein, the optical fiber ribbon having a longitudinal axis. The sub-units include strength fibers, the strength fibers generally surrounding and contacting the optical fiber ribbon in the jacket and being stranded about the optical fiber ribbon resiliently twisting the optical fiber ribbon about the longitudinal axis thereof.
Another aspect of the invention is a fiber optic zipcord cable, comprising optical sub-units with respective jackets connected by a frangible section, and respective optical fiber ribbons in the sub-units, the optical fiber ribbons each having a longitudinal axis. The strength fibers are respectively disposed in the sub-units and generally surround the optical fiber ribbons and resiliently twist the optical fiber ribbons about their respective longitudinal axes.
Another aspect of the invention is a method of making an optical fiber cable, comprising the steps of: stranding strength fibers about an optical fiber ribbon causing the optical fiber ribbon to be generally twisted about its longitudinal axis; and extruding a molten jacketing material about the stranded strength fibers and the twisted optical fiber ribbon.
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Siecor Cable Product Code Guidebook, Flame-Retardant Cables, pp. 24 and 26, Jul. 1997.
Siecor Product Information, Plenum Ribbon Interconnect Cables, Nov. 1998.
Siecor Product Information, Non-Plenum Ribbon Interconnect Cables, Sep. 1998.
Burel Chad A.
Harwell-Rutterman Shannon N.
Rutterman Daniel J.
Aberle Timothy J.
Boutsikaris Leo
Siecor Operations LLC
Spyrou Cassandra
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