Abstract:
A fiber cable having a first fiber containing portion with a plurality of optional fibers disposed therein. A second strength portion is separable from the first fiber containing portion arranged in a substantially flat arrangement. The second strength portion is separatably coupled to the first fiber containing portion.

Description:
FIELD OF THE INVENTION 
   The present invention relates to the field of fiber optic cables. More particularly, the present invention relates to an improved flat design composite drop fiber optic cable having mid-span access capability. 
   BACKGROUND OF THE INVENTION 
   With the addition of more home fiber optic services, fiber optic cables, such as telephone and internet access fiber cables, are commonly hung from telephone poles and extend to the houses which they service. These cables are typically hung using a variety of clamps such as P-clamps (having a shell bail shim and wedge component). These P-clamps assist in suspending the fiber cable by attaching the fiber cable to hooks located on the poles and on the house or apartment building. 
   These clamps transmit pressure on fibers within the fiber tubes in a fiber cable if the cable design is oval. Furthermore, the non-rectangular (flat) design may result in the wedge and shims of the clamp rolling or bending under the curves of the cable, causing the edges to pull away from the guide slots resulting in clamp failure. 
   Alternative flat cables are available, however, one major problem with this common flat design drop cable installation is that the fiber cable is subject to a high amount of tension between the two clamps in the span from the telephone pole to the house. Currently used flat drop fiber cable designs, typically sandwich the fiber portions of the cable between the strength portions of the cable. Such arrangements cause the fiber tube portion of the cable to be crushed when attached to the clamps, when tighter clamp tension is applied. This “loose sandwich” approach may result in minimal adhesion and coefficient of friction transfer to the strength members. 
   For example, as shown in  FIG. 1(   a )- 1 ( f ), prior art designs typically include a tube containing optical fibers surrounded by a jacket flanked on both sides by strength members. Also shown in  FIG. 1(   b ), another prior art design includes additional strength members set off to the side of the cable. Some prior art arrangements shown in  FIGS. 1(   c ) and  1 ( d ) also employ yarns added around the rigid strength members in an attempt to add strength to the design. However, these yarns have the effect of further reducing the jacket&#39;s adhesion to the constituents, thereby reducing the efficiency of the clamp-fiber cable assembly. 
   Another drawback associated with the prior art designs shown in  FIGS. 1(   a )- 1 ( f ) is that they require that the jacket be applied loosely around the strength members so as not to lock in the tube too tightly. If the jacket is too loose in such designs, the fiber cable and clamp connection may fail with the jacket tearing away from the cable constituents underneath within the clamp or at the exit of the clamp. 
   Yet another drawback with the prior art designs as shown in  FIGS. 1(   a )- 1 ( f ) is that they require that an installer disassemble the strength portion of the cable in order to access the optical fibers. The center tube configuration of these prior art designs, where the tube containing the optical fibers is located centrally in between the strength members, requires that the cable be destroyed for mid-span access of the fiber. 
   As such, these prior art designs lack sufficient strength due to P-clamp space constraints and may fail within spans of, or in excess of, 150 feet in heavy wind and ice load. 
   OBJECTS AND SUMMARY OF THE INVENTION 
   The present invention provides an improved flat design composite drop fiber cable having a tube containing fibers, set off to the side of the strength members. The fiber containing tube portion of the flat design drop cable is attached adjacent to the strength members on one side. Such an arrangement allows the installer to use just the strength portion of the cable to connect to the pole and house clamps (high tension portion) and can merely tear off the fiber tube portion in order to attach the low tension house and pole connections to the transmission equipment, while also allowing mid-span access to the optical fibers without the need to completely disassemble the strength portion of the cable. Furthermore, the flat design of the strength portion of the cable makes the cable ready for use with the existing P-clamps or wedges (which have two flat shaped clamping sides). 
   To this end, the present invention is directed to a fiber cable having a first fiber containing portion having a plurality of optional fibers disposed therein, a second strength portion separable from the first fiber containing portion arranged in a substantially flat arrangement. The second strength portion is separatably coupled to the first fiber containing portion. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIGS. 1(   a )- 1 ( f ) illustrate a variety of prior art flat design drop cables; 
       FIGS. 2A and 2B  are cross sectional views of fiber cables in accordance with one embodiment of the present invention; 
       FIGS. 3A and 3B  is an illustration of a fiber cable installation; 
       FIGS. 4A and 4B  are cross sectional views of fiber cables in accordance with one embodiment of the present invention; 
       FIG. 5  is a cross sectional view of a fiber cable in accordance with one embodiment of the present invention; 
       FIGS. 6A and 6B  are cross sectional views of fiber cables in accordance with one embodiment of the present invention; 
       FIGS. 7A ,  7 B and  7 C are cross sectional views of fiber cables in accordance with one embodiment of the present invention; and 
       FIGS. 8A and 8B  are side elevational views of fiber cables in accordance with one embodiment of the present invention. 
   

   DETAILED DESCRIPTION 
   In one aspect as illustrated in  FIGS. 2A and 2B  an arrangement for a cable  10  is shown having an outer jacket  12  having a fiber section  20  and a strength section  30 . Cable  10  is of a flat design type for accommodation within standard clamp designs. In  FIG. 2A , fiber section  20  of jacket  12  includes a plurality of fibers  14  within a fiber tube  16 . Strength section  30  includes a plurality of strength members  32 . Between strength section  30  and fiber section  20 , jacket  12  maintains a fiber disconnect notch  40 , that is significantly smaller than the outer dimensions of the fiber portion  20  and strength portion  30  of jacket  12  allowing fiber portion  20  to be easily disconnected from strength portion  30 . 
   It is understood that the number of fibers  14  in tube  16  are preferably  6 , but the invention is not limited in that respect. Several tube designs may be used for tube  16  including additional components including but not limited to gel filler, dry with SAP (super absorbent powder), or yarns having SAP (not shown). 
   Furthermore,  FIGS. 2A and 2B  show the preferable arrangement of three strength members  32 . However, the invention is not limited in this respect. More or less strength members may be used depending on the desired specifications, provided the resulting cable  10  is still within usable physical size constraints. In  FIG. 2A  strength members  32  may be formed of a metal (steel, etc . . . ). As shown in  FIG. 2B , strength members  32  may be formed of a fiber/plastic material such as aramid fiber, fiberglass, thermosetting resin, dielectric composite, epoxy and/or GRP (Glass Reinforced Plastic), or some combination thereof. 
   The dimensions of cable  10  are preferably compatible with existing clamps used for pole and home side connections. For examples, typical clamps are configured to accommodate either 0.500″ width cable or 0.630″ cables. Thus, cable  10  would be dimensioned to have a width of equal or lesser value, preferably in the range of 80-90% of the interior width of the clamp to prevent the interior bending or curvature of the wedge or grip shims. 
   One exemplary dimension for cable  10  is substantially 0.500″ wide and 0.160″-0.180″ inches thick. Of this, strength portion  30  is substantially 0.300″ wide and the remaining width encompasses fiber portion  20  and disconnect notch  40 . In another example, if increased flexibility is Desired, the overall width may reduced to 0.300″-0.320″. Preferably, the thickness of notch  40  is in the range of 60% +/−5-10% of the thickness of the portion of jacket  12  adjacent to notch  40 . Such a range is useful for maintaining the connection between fiber portion  20  and strength portion  30 , while being reduced enough to allow separation of the two without damaging the near by areas of jacket  12  along strength portion  30  and fiber portion  20 . 
   As shown in  FIG. 3A , the above described arrangement allows the strength portion  30  of cable  10  to be utilized in between the clamps on the house and pole sides (under high tension), and beyond the clamps, fiber portion  20  free from any imparted tension, may be separated by cutting/ripping fiber disconnect notch  40 , just before the clamps for attachment to the fiber communication equipment (under low tension). Additionally, such an arrangement, by separating the fibers to the separatable fiber portion  20 , allows an installer to achieve mid-span access of fibers  14  at any point along cable  10  without the need to damage or unwind any portion of strength members  32  in the separate strength portion  30  of jacket  12 . 
   In another aspect,  FIG. 3B  shows a different installation whereby four clamps are used, two on the pole side and two on the home/building side. Such an arrangement may be used in installations where high wind/ice conditions are expected. Here a first clamp from the pole and a first clamp from the building attach to cable  10  as a whole. Then a second clamp closer to the house, and second clamp closer to the pole is attached similar to the first arrangement where fiber portions  20  are disconnected prior to the clamps which grip only against strength portions  30 . This allows the brunt of the tension to be supported by the two second clamps (attached only to strength portions  30 ) with the first set of clamps (attached to all of cable  10 ) to provide additional support and to maintain the connection in the case of the failure of one clamp in wind or ice conditions. 
   In another aspect,  FIGS. 4A-4B , illustrate alternative arrangements for cable  10 . In  FIGS. 4A-4B , rather than encasing fibers  14  within (a separate jacket  18 ) tube  16 , fibers  14  are simply held within an open space in fiber portion  20  of jacket  12 . Furthermore,  FIG. 4C  shows an alternative arrangement for strength members  32  that employ a plurality of stranded aramid/GRP fibers rather than single composite (thicker) strength fibers to add flexibility to strength portion  30  so as to avoid fracture conditions over very tight bend radii. 
   In another aspect,  FIG. 5  shows reduced size GRP strength members  32  in strength portion  30  so that polymer used to form jacket  12  entirely encases/envelops strength members  32  rather than in the above example in  FIG. 4B . Such an arrangement prevents breakout of strength members  32  through jacket  12  over long term exposure to wind and ice. Furthermore, the lateral support of strength members  32  by jacket  12  reduce fracture incidents when subjected to very small bend radii. 
   In another aspect,  FIGS. 6A and 6B , show an alternative strength portion  30  arrangement whereby strength portions  30  each have two strength members  32  disposed one on either side of a central metal conductor  34 . In  FIG. 6A , strength members  32  are large single GRP/composite materials. In  FIG. 6B , strength members  32  are a grouping of smaller diameter GRP/composite materials. In another arrangement, one or more of strength members  32  may be formed from a metallic/conductor so that they can act as both strength member  32  and conductor  34 . 
   In such, an arrangement, cable  10  may not only be utilized for fiber connection from pole to house using fiber portion  20  but also a power connection from pole to house using central conductor  34  in strength portion  30 , for example to provide a 60 volt power backup for the fiber equipment in the event of a power failure from the primary supply. It is understood that any use for power from conductors  34  in cable  10  is within the contemplation of the present invention. 
   In another aspect, as shown in  FIGS. 7A through 7C , strength section individual separation notches  36  are added to the arrangements from  FIGS. 6A and 6B  so that an installer may separate either one of strength members  32  or conductor  34  so as to be able to better fit cable  10  within the desired clamps and to potentially separate conductor  34  to other connection points on the pole and house ends. Such separation notches  36  can be used on any of the previously described designs;  2 A,  2 B,  4 A- 4 C,  5 ,  6 A, and  6 B or on other designs used for more flexibility in strength member  32  usage, such as the arrangement shown in  FIG. 7C . 
   In another arrangement, fiber portion  20  may be extruded in a waved arrangement so as to additionally reduce fiber strain during installation. For example,  FIG. 8A  shows a typical side elevation arrangement for cable  10 , with fiber portion  20  in a standard flat configuration. Alternatively,  FIG. 8B  shows an oscillated arrangement for fiber portion  20 . In this arrangement, fibers  14  in fiber portion  20  have an additional amount of slack relative to the length of strength portion  30 . This arrangement provides additional protection for fibers  14  during the high tension installation between the clamps by allowing more length/freedom for installation without incurring any attenuation due to bending or other installation stresses. 
   As such, the above arrangements allow the fiber portion  20  to be separated from cable  10  just prior to the P clamp allowing the clamp to compress only strength members  32  in strength portion  30 . In this way utilization of the P clamp is optimized with respect to the level of adhesion and coefficient of friction caused between strength members  32  and jacket  12  without damaging fibers  14 . This arrangement allows for increased usage in longer spans between home/apartments and the poles from which they originate. Furthermore, the arrangement allows for mid-span access of fibers  14  potentially allowing a single drop cable  10  to support several houses on the same street while also potentially providing back-up power in the event of a power failure. 
   While only certain features of the invention have been illustrated and described herein, many modifications, substitutions, changes or equivalents will now occur to those skilled in the art. It is therefore, to be understood that this application is intended to cover all such modifications and changes that fall within the true spirit of the invention.