Patent ID: 12248193

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

The present invention now is described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

Like numbers refer to like elements throughout. In the figures, the thickness of certain lines, layers, components, elements or features may be exaggerated for clarity. Broken lines illustrate optional features or operations unless specified otherwise.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the specification and relevant art and should not be interpreted in an idealized or overly formal sense unless expressly so defined herein. Well-known functions or constructions may not be described in detail for brevity and/or clarity.

As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “comprises” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. As used herein, phrases such as “between X and Y” and “between about X and Y” should be interpreted to include X and Y. As used herein, phrases such as “between about X and Y” mean “between about X and about Y.” As used herein, phrases such as “from about X to Y” mean “from about X to about Y.”

It will be understood that when an element is referred to as being “on”, “attached” to, “connected” to, “coupled” with, “contacting”, etc., another element, it can be directly on, attached to, connected to, coupled with or contacting the other element or intervening elements may also be present. In contrast, when an element is referred to as being, for example, “directly on”, “directly attached” to, “directly connected” to, “directly coupled” with or “directly contacting” another element, there are no intervening elements present. It will also be appreciated by those of skill in the art that references to a structure or feature that is disposed “adjacent” another feature may have portions that overlap or underlie the adjacent feature.

Spatially relative terms, such as “under”, “below”, “lower”, “over”, “upper”, “lateral”, “left”, “right” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures is inverted, elements described as “under” or “beneath” other elements or features would then be oriented “over” the other elements or features. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the descriptors of relative spatial relationships used herein interpreted accordingly.

FIG.7is a front perspective view of a fiber optic cable41in accordance with the present invention.FIG.8is a cross sectional view taken along line VIII-VIII inFIG.7. The fiber optic cable41includes an inner core43. The inner core43includes a plurality of buffer tubes, such as first, second, third and fourth buffer tubes45,47,49and51. Each of the first, second, third and fourth buffer tubes45,47,49and51has a diameter between 0.9 mm and 1.5 mm, such as between 1.1 mm and 1.3 mm, for example about 1.2 mm.

Each of the first, second, third and fourth buffer tubes45,47,49and51includes a plurality of optical fibers53therein. In the depicted embodiments, each of the first, second, third and fourth buffer tubes45,47,49and51includes six optical fibers53. However, more or fewer optical fibers53may be included, and different numbers of optical fibers53may be included in each of the first, second, third and fourth buffer tubes45,47,49and51.

A central strength member63is provided along a central axis X of the fiber optic cable41. A diameter of the central strength member63is between 1.9 mm and 2.9 mm, such as between 2.2 mm and 2.6 mm, for example about 2.4 mm. In the embodiment ofFIGS.7and8, the central strength member63is formed of a core65surrounded by a sheath67, to form an up jacketed central strength member63. When up-jacketed, the sheath67has an outer diameter of about 2.4 mm, while the core65may have a diameter of about 1.6 mm. The core65may be formed as a glass reinforced plastic (GRP) rod, while the sheath67may be formed of a polymer material, such as a low-smoke, zero-halogen polymer. If the sheath67is not used, the entire central strength member63may be formed as a GRP rod.

A plurality of filler rods, such as first, second, third and fourth filler rods55,57,59and61are stranded with the plurality of buffer tubes45,47,49and51around the central strength member63. The stranding may be in one direction, such as clockwise twisting of the buffer tubes45,47,49and51and the filler rods55,57,59and61about the central strength member63inFIG.8. However, in another embodiment, the stranding is in a S-Z pattern with switchbacks, where the clockwise twisting about the central strength member63changes to counterclockwise and vice versa at the switchbacks along the length of the fiber optic cable41. Each of the first, second, third and fourth filler rods55,57,59and61has a diameter between 1.1 mm and 1.7 mm, such as between 1.3 mm and 1.6 mm, for example about 1.4 mm or about 1.5 mm. The first, second, third and fourth filler rods55,57,59and61are preferably formed of a low smoke zero halogen (LSZH) material.

Finally, a jacket69surrounds the cable core41. An outer diameter of the jacket69is between 7.0 mm and 9.4 mm, such as between 7.6 mm and 8.8 mm, for example 8.6 mm. The jacket69may be formed of any polymer material, however an ultra low smoke zero halogen (ULSZH) material is preferred. The jacket69may include one or more stripes of a contrasting color, to help identify the fiber optic cable41. For example, the majority of the jacket69may be black and the one or more stripes of a red, yellow and/or green color may be embedded within or printed onto the jacket69.

A characterizing feature is that a diameter of each filler rod of the plurality of filler rods55,57,59and61is more than 10% larger in diameter as compared to each buffer tube of the plurality of buffer tubes45,47,49and51. For example, filler rods with a diameter of 1.4 mm are about 17% larger in diameter as compared to buffer tubes with a 1.2 mm diameter.

As seen inFIGS.7and8, the jacket69may optionally include first and second embedded strength members71and73therein. The first and second embedded strength members71and73are preferably GRP rods spaced one hundred eighty degrees apart from each other within a wall forming the jacket69. The first and second embedded strength members71and73could potentially be formed as metallic rods, so as to enable toning of the fiber optic cable41, should the fiber optic cable41need to be located underground or amongst a plurality of cables.

FIGS.7and8also show a plurality of textile strength elements75, such as yarns, within the jacket69. The yarns surround the cable core43. The yarns may be formed into bundles of fibers, each of which extends longitudinally along the length of the fiber optic cable41. Alternatively, the yarns may be formed into a first grouping and a second grouping of yarns. The first grouping of yarns is helically wrapped around the cable core43in a first wrapping direction. The second grouping of yarns is helically wrapped around the cable core43in a second wrapping direction, opposite to the first wrapping direction. The first and second groupings of yarns cross over each other to hold the elements of the cable core43together during manufacturing of the fiber optic cable41. In a preferred embodiment, the textile strength elements75, are formed of flaccid threads or yarns, like E-Glass strength members or aramid fibers, sold under the trademark KELVAR.

As seen inFIGS.7and8, the fiber optic cable includes at least one rip cord, such as first and second rip cords77and79within the jacket69. The first and second ripcords77and79assist in opening up an end of the fiber optic cable41for a termination to one or more connectors. The first and second rip cords77and79may also be formed of flaccid threads, like aramid threads, sold under the trademark KELVAR.FIGS.7and8also show at least one water blocking tape or thread, such as first and second water blocking threads81and83included within the cable core43.

FIG.9shows the stranding pattern around the central strength member63, the first, second, third and fourth filler rods55,57,59and61are diametrically opposite to each other. Hence, as illustrated inFIG.9, with the diametrically opposed pinching forces A, C, E, G and I applied to the jacket69, the forces applied at A, C, E, G and I are supported by the filler rods55,57,59and61. In other words, the pinching forces applied to the jacket69at locations A, C, E, G and I are well supported by the abutments between the central strength member63and the filler rods55,57,59, and61on either side of the central strength member63.

Contrary to the embodiments of the prior art, crush is not likely to occur when pinch or lateral forces are applied at the other locations B, D, F and H. This is because the oversized filler rods55,57,59and61act as supports to keep the force applied to the jacket69at locations B, D, F and H from reaching the buffer tubes45,47,49and51. In other words, the filler rods55,57,59and61act as table legs and the jacket69acts as a table top. For example, when a force is applied to location B, the jacket69(table top) causes the force to be split and support by the first and second filler rods55and57. The first and second filler rods55and57directly abut the central strength member63. Hence, the jacket69would need to deform a significant amount before any of the force at location B would allow the jacket69to contact the second buffer tube47.

FIG.10is a cross sectional view similar toFIG.8of a modified fiber optic cable41′. The modified fiber optic cable41′ is an alternative to the fiber optic cable41. The only changes are that the first and second embedded strength members71and73are not included within the jacket69′, and the wall forming the jacket69′ has been made thinner. The central strength member63′ does not include a sheath67, and can be made of a smaller diameter, if desired. The filler rods55,57,59and61may also be made of a slightly smaller diameter, if desired. The changes result in the modified fiber optic cable41′ having an overall diameter of about 7.8 mm.

In the above embodiments, the filler rods55,57,59and61may be formed of a dielectric plastic, and directly abut the central strength member63. The central strength member63, due to its embedded fiberglass segments, provides a high degree of strength to the fiber optic cable41,41′. The filler rods55,57,59and61do not provide much added strength to the fiber optic cable41,41′, but primarily assist in preventing a crushing of the buffer tubes45,47,49and51within cable core43. The filler rods55,57,59and61may also assist in keeping the overall outer cross sectional shape of the fiber optic cable41,41′ circular, so that the fiber optic cable41,41′ can be stored and transported on a reel and deployed in the field more easily.

Although each buffer tube45,47,49and51has been illustrated as having six optical fibers53, other numbers of optical fibers53are possible, such as four, eight, ten or twelve optical fibers53, preferably surrounded by a gel, such as a water blocking gel, within the buffer tubes45,47,49and51. Instead of a gel, it would also be possible to include a water blocking thread or tape within each buffer tube45,47,49and51.

FIGS.7-10illustrated six optical fibers loosely contained within each of the four buffer tubes45,47,49and51, making a total of 24 optical fibers in the fiber optic cable41,41′. However, it would be possible to replace one or more of the buffer tubes45,47,49and51with yet another filler rod, such as a dielectric member of a same diameter as the replaced buffer tube, to reduce the fiber count of the fiber optic cable41,41′.

The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.