Electricity: conductors and insulators – Conduits – cables or conductors – Insulated
Reexamination Certificate
1999-08-06
2001-07-10
Reichard, Dean A. (Department: 2831)
Electricity: conductors and insulators
Conduits, cables or conductors
Insulated
C174S1130AS, C174S1130AS, C174S116000
Reexamination Certificate
active
06259031
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to cables, and more particularly to cables comprising an odd number of conductor pairs.
BACKGROUND OF THE INVENTION
Various telecommunication systems require communication cables comprising an odd number of conductor pairs. A commonly used cable for such purposes is the twenty-five pair, category five cable. This cable, like other cables, must comply with associated TIA/EIA requirements. Various cable construction techniques have been tried by cable manufacturers in an attempt to pass the power sum near-end crosstalk (NEXT) specification for TIA/EIA twenty-five pair category five cables.
For a plenum product, the use of a filler having a star configuration would not allow the product to pass the UL
910
burn test. This is so because the star filler greatly increases the percentage of combustible plastics when compared to a copper heat sink based upon presently known state of the art materials.
The layout of the pairs of conductors comprising a cable is critical in the cable passing the TIA/EIA power sum NEXT electrical specification. One of the more successful attempts utilized a cable construction having the twenty-fifth pair jacketed and used as a center filler with six quads using two or more different pair lay schemes and one or more different quad lay lengths (L) surrounding the filler. However, the location of the twenty-fifth pair inside the filler causes increased installation times and potential for damage. For example, in cables utilizing such a cable layout, the twenty-fifth pair is prone to damage when stripping off the end of the rather thick filler jacket during installation.
Several different cable constructions have been attempted in the past, including having the twenty-fifth pair pulled straight in between two of the quads, having the twenty-fifth pair placed by the center along with the tube filler, and laying the twenty-fifth pair on the outside of the cable core. However, the cables fail to meet the TIA/EIA power sum NEXT requirements for the twenty-fifth pair. In addition, the cables also failed signal reflection loss (SRL), impedance, and attenuation requirements due to instability in the twenty-fifth pair.
It was also found that the twenty-fifth pair interfered with the pairs in the quads closest to it. The damage to the insulation of the twenty-fifth pair was caused by the twenty-fifth pair being pinched between quads, or being pinched between the quads and the filler, or being pinched between the core and the jacket.
A cable construction involving jacketing twelve and thirteen pairs of conductors together to yield a twenty-five pair cable has also been attempted with limited success. For example, the resulting shape of the cable is not round, thus making it harder to install, specifically with regard to conduit fill.
SUMMARY OF THE INVENTION
The present invention is directed to a cable, which includes an even number of paired conductors, along with an additional couple of conductors. Thus, the total number of paired conductors is an odd number. The even number of paired conductors are evenly divided into groups of at least two conductor pairs. The additional pair of conductors is paired with, and encircles a filler material along its length. The groups of conductor pairs and the additional pair that is coupled with the filler material extend in parallel to form the cable so the groups of conductor pairs surround the additional pair and the filler material. A jacket material surrounds the conductor pairs and the filler material.
In one embodiment of the invention, the filler material has a larger diameter than the additional pair of conductors, and the filler material is twined with the additional pair of conductors, so that the filler material causes an air gap to surround any portion of the additional pair of conductors that is not in contact with the filler material. In another embodiment of the invention, the filler material secures the additional pair of conductors within a longitudinal groove formed in the filler material.
In a preferred embodiment of the invention, the filler material has a dielectric constant higher than a dielectric constant of air. More particularly, the filler material is selected from at least one of the following: polyfluoroalkoxy, TFE/Perfluoromethyl-vinylether, ethylene chlorotrifluoroethylene, polyvinyl chloride, fluorinated perfluoroethylene polypropylene and flame retardant polypropylene.
Also in a preferred embodiment of the invention, the jacket material includes a dielectric layer. The dielectric layer can be a single or a multiple dielectric layer, with each layer comprising at least one of the following: low smoke zero halogen, polyvinyl chloride, flame retardant polyethylene, linear low density polyethylene, polyvinylidene fluoride, ethylene chlorotrifluoroethylene, fluorinated ethylene-propylene, thermoplastic elastomer, and polyurethane.
Each conductor can be a bare copper wire, and each should be insulated with an insulating material having a dielectric constant no greater than about 2.5. Normally, each bare copper wire is between 22 AWG and 24 AWG. The insulating material preferably includes at least one of the following: flame retardant polyethylene, flame retardant polypropylene, high density polyethylene, polypropylene, polyfluoroalkoxy, solid or foamed TFE/perfluoromethylvinylether, solid or foamed fluorinated ethylene-propylene, and foamed ethylene chlorotrifluoroethylene.
The present invention is also directed to a method for manufacturing the above-described cable. First, the couples of conductors are paired with each other to make an even number of pairs. Then, the additional couple of conductors are paired, making the total number of paired conductors an odd number. The even number of paired conductors are then evenly divided into groups of at least two conductor pairs. The additional pair of conductors are coupled with, and encircled around the filler material along its length, and the groups of conductor pairs, and the additional pair coupled with the filler material are extended in parallel to form a cable so the groups of conductor pairs surround the additional pair of conductors and the filler material. Finally, the cable is surrounded by a jacket material.
REFERENCES:
patent: 2584027 (1952-01-01), Kendrick
patent: 3843829 (1974-10-01), Bridge et al.
patent: 3983313 (1976-09-01), Ney et al.
patent: 5110999 (1992-05-01), Barbera
patent: 5789711 (1998-08-01), Gaeris et al.
patent: 5883334 (1999-03-01), Newmoyer et al.
patent: 5952615 (1999-09-01), Prudhon
Berelsman Timothy N.
Grabowski Joseph W.
Totland Rune
Krone Digital Communications
Mayo III William H.
Rader & Fishman & Grauer, PLLC
Reichard Dean A.
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