Optical waveguides – Optical transmission cable – Loose tube type
Reexamination Certificate
1998-11-12
2001-01-23
Ngo, Hung N. (Department: 2874)
Optical waveguides
Optical transmission cable
Loose tube type
Reexamination Certificate
active
06178278
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
This invention relates to an optical fiber cable; and more particularly relates to an indoor/outdoor optical fiber cable that meets various competing industry standards such as peak flame, peak smoke, average smoke, compression and cold temperature bend tests.
2. Description of Related Art
Campus cables are known in the art and include four (4) categories, such as outdoor, outdoor-riser, riser and plenum cable designs. Balancing the industry specifications with current demand, results in strategic performance targets for such cables which include flame peak, smoke peak, average smoke, cold bend, compression, and temperature cycling attenuation.
Campus cables with components made of polyvinyl chlorides (PVC) have a difficult time consistently passing the average smoke requirement for the Underwriters Laboratory (UL) 910 test; while cables with components made of polyvinylidene fluorides (PVDF) generate very little smoke but do not process well when pressure extruded around fiberglass yarns.
Existing yarn-matrix units with or without water swellable powder are not flame and smoke retardant. Some yarn-matrix combinations exhibit low smoke and relatively low flame but do burn easily and are not considered flame retardant.
In the prior art, when running cable between buildings, an indoor plenum cable is used in combination with an outdoor cable. One of the major disadvantages of this approach is that the indoor plenum cable must be spliced to the outdoor cable and the cost of splicing is more expensive than the actual cost of the cable.
First Patentability Search
A first patentability search was conducted in the United States Patent and Trademark Office for patents related to an indoor/outdoor cable using plenum (i.e. flame retardant) material. The field of the patentability search included class 385, subclasses 109-114. The following patents were found:
U.S. Pat. No. 4,743,085 discloses a fiber cable that includes a polyethylene or polyvinyl chloride (PVC) core buffer tube 28 enclosing plural fibers 23, and an outer plastic jacket 36. See column 4, lines 13-25. First and second layers of strength members 40 and 50 of glass fiber yarn are included between the core tube and jacket. A waterblocking material 29 is included in the core tube. (See FIGS. 1-3.)
U.S. Pat. No. 5,050,957 discloses a fiber service cable which has a central buffer tube 40 formed of polybutylene terephthalate (PBT) or polypropylene (PP) material, and a jacket 44 formed of PVC. Fibers 22 and a waterblocking material are located within the buffer tube. A rip cord 58 having an encircling waterblocking yarn are included as taught in the paragraph bridging columns 8 and 9. Strength members 54 are also included as shown in FIG. 1. (See also column 4, lines 21-26, and column 5, lines 63-68.) The PVC jacket is flame-retardant as described in column 8, lines 50-58.
U.S. Pat. No. 5,561,729 discloses a fiber cable which has a central buffer tube 11 and a jacket 22 both of which may be formed of PVC, PBT or PVDF. See column 4, lines 47-56. Glass reinforcement fibers may be included in the materials.
U.S. Pat. No. 5,566,266 discloses a fiber service cable that has a single layer core tube of PBT material or a double layer with the inner layer being polycarbonate and the outer layer PBT, as described on column 2, lines 62-67. The outer jacket 22 is made of flame retardant PVC or flame retardant PVDF, as described on column 3, lines 33-37. Strength members 18 having water swellable material may be stranded about the core tube, as described on column 3, lines 14-18.
U.S. Pat. No. 5,748,823 discloses a fiber cable that is suitable for use in building plenums. The cable includes a core tube formed of PVC or PVDF, and a jacket 5 formed of PVC or PVDF. See table 1 in column 3. Layers 6 and 12 of fiberglass yarns are disposed about the core tube 8, as described on column 5, lines 1-8.
Second Patentability Search
A second patentability search was conducted in the United States Patent and Trademark Office for patents related to a combined indoor/outdoor cable using polyvinylidene fluoride (PVDF) in combination with flame retardant polyvinyl chloride (FRPVC). The field of search included class 385, subclasses 109-114. The following patents were found:
U.S. Pat. No. 4,770,489 discloses a fiber cable which has a central buffer tube 34 formed of polyester plastic, and an outer jacket 38 formed of a fiber reinforced plastic, as shown in FIG. 2A and described on column 3, lines 42-52.
U.S. Pat. No. 4,818,060 discloses a fiber building cable which, as shown in FIGS. 1-5, includes a central buffer tube 30 formed of PVC, and an outer jacket 37 formed of PFC or PVDF, as described on column 4, lines 66-68; and column 6, lines 10-14. The cable also has two strength layers 42 and 52 with portions of the layer 52 being coupled to the jacket 37, as described on column 8, lines 34-47.
U.S. Pat. No. 5,050,957 discloses a fiber cable having a buffer tube 40 formed of PBT, and an outer jacket
44
formed of PVC, as described on column 4, lines 29-34; and column 5, lines 63-68. The jacket has strength members 54 embedded therein, as shown in FIG. 1 and described on column 6, lines 33-43.
U.S. Pat. No. 5,561,729 discloses a fiber cable which uses fiber reinforced plastic in the buffer tube and jacket. The buffer tube 11 and jacket 22 can be formed of the several plastics described on column 4, lines 47-56. These plastics include PVC and PVDF or a combination thereof. FIG. 2 shows the use of reinforcing fibers 20 in the plastic that may be used in tubes 11 or 22. U.S. Pat. No. 5,561,729 does not disclose or suggest to use PVDF in combination with flame retardant polyvinyl chloride (FRPVC) for passing the average smoke requirement for the UL 910 test as well as the cold bend, compression, and temperature cycling attenuation industry tests.
U.S. Pat. No. 5,566,266 discloses a fiber cable which has a PBT buffer tube 11, and a jacket 22 formed of PVDF or PVC, as described on column 2, lines 62-67; and column 3, lines 33-36. Strength members 15 are partially embedded in the jacket 22.
U.S. Pat. No. 5,748,823 discloses a fiber cable suitable for use in building plenums. The cable has a core tube which may be formed of PVC or PVDF, and a jacket which may be formed of PVC or PVDF. See the Table in column 3. Layers of strength members 6 and 12 are included around core tube 8 such that when the jacket 5 is pressure extruded, the material flows around at least the outer layer, as described on column 5, lines 9-14.
Third Patentability Search
A third patentability search was conducted in the United States Patent and Trademark Office for patents related to a cable having trace amounts of water swellable powder sprinkled on the optical fiber. The field of search included class 385, subclasses 102, 109-114; and class 523, subclass 173. The following patents were found:
U.S. Pat. No. 4,401,366 discloses a fiber optic cable that includes a central core 12 with grooves 16 supporting optical waveguides 18 within an outer sheath 22, as shown in FIG. 1. A mixture of hydrophilic powder and hydrophobic powder is included around the waveguides as described on column 3, lines 58-68.
U.S. Pat. No. 5,684,904 discloses an optical fiber cable that includes buffer tubes 20 wherein a coating formed from a mixture of moisture-absorptive powder and resin is applied to the inner buffer tube surface, outer buffer tube surface or both inner and outer surfaces. FIG. 2 shows a coating 19 on the inner surface of a buffer tube 8, and FIG. 3 shows all of the suggested coating alternatives, as described on column 3, lines 42-60, and column 4, lines 35-42.
U.S. Pat. No. 5,698,615 discloses optical cables that include a filler material composed of water swelling powder and an additive powder, as shown in FIG. 7 and described on column 10, lines 57-64. The filling compounds have been used in electrical and optical cables, as described in the paragraph bridging columns 13 and 14.
Japanese patent No. 58-10703 discloses an optical fiber cable that includes
Keller David A.
Keller Leslie P.
Rosko John C.
Alcatel
Ngo Hung N.
Ware Fressola Van der Sluys & Adolphson LLP
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