Optical waveguides – Optical transmission cable – Tightly confined
Reexamination Certificate
2000-06-13
2003-05-13
Feild, Lynn D. (Department: 2839)
Optical waveguides
Optical transmission cable
Tightly confined
Reexamination Certificate
active
06563991
ABSTRACT:
BACKGROUND THE INVENTION
1. Field of Invention
The present invention relates to an optical cable having ripcords that are easily accessible, and wherein the ripcords can be used reliably without damaging the optical cable and without breakage.
2. Background of Related Art
An optical cable may include a ripcord that facilitates the removal of portions of cable armor or other protective sheathing disposed about a fiber bundle in order to gain access to the fiber bundle. However, the placement of ripcords in conventional optical cables may result in the ripcord being cut by the edge of the protective armor tape when the ripcord is used. When the ripcord becomes cut, the cable must be re-prepped, which is a time-consuming and tedious process.
Additionally, the ripcord may also be cut due to wearing against a radial strength member (RSM). This occurs when the ripcord is pulled through the wrong portion of the sheath. In such a situation, the intervening RSM may also prevent the ripcord from adequately tearing through the cable sheathing. Conventional placement of the ripcord, which permits the ripcord to be pulled incorrectly through the cable housing, may also cause damage to the fiber bundle in the central cavity of the optical cable.
Ripcords placed without due regard to the above considerations may also be accidentally cut when the cable is being prepped. Furthermore, random placement of the ripcords may not provide a sufficient window opening in the sheath, which makes it difficult to extract the cable core from its housing.
SUMMARY OF THE INVENTION
The present invention obviates the above deficiencies of known fiber cables by placing the ripcords included in the cable armor with reference to the position of the cable armor overlap and also with reference to radial strength members included in the cable. In particular, ripcords are placed at least 45 degrees, preferably 90 degrees ±20 degrees, off the center from the armor tape overlap. With regard to ripcord placement relative to a radial strength member, the ripcord can be extruded into the cable jacket along with the radial strength members. The ripcords are placed anywhere on the 270 degree arc, centered toward the cable cavity, around each RSM. In this manner, the position of the ripcords will not shift, and their position near the RSM mitigates the risk of age due to a service technician's misplaced cut. The cable and ripcords can also be marked by color coding, texturing or printed matter so that the ripcord is pulled in the correct direction to avoid being damaged by the RSM.
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Robinson Rick
Shen Steve
Stevens J. Boyet
Witt Geoff
Dinh Phuong
Feild Lynn D.
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