Abstract:
Optical fiber cable with at least one optical fiber and with a tube surrounding each and every optical fiber, especially made of plastic, comprising at least one string-like element, which can be pulled out, being added to the tube for easy access to each and every optical fiber.

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to fiber optic cables and, more particularly, to fiber optic cables having at least one ripcord. 
     BACKGROUND OF THE INVENTION 
     For optical fiber cables of the above type, contain several optical fibers, also called light conductor fibers, that are arranged in a tube, preferably made of plastic. During installation of the optical fiber cable, connection to another optical fiber cable or connection of a subscriber, the optical fibers have to be accessible and thus able to be exposed, in order to connect other optical fibers at a so-called panel point. 
     Exposing the optical fibers in optical fiber cables can only be done with much effort according to the state-of-the-arts. For an optical fiber cable stranded with equal lay, the cable has to be severed with all optical fibers. This is especially disadvantageous, if only a few optical fibers have to be severed and spliced together in order to produce a panel point. 
     From this, the present invention has the objective to create a new type of optical fiber cable. 
     SUMMARY OF THE INVENTION 
     Optical fiber cable with at least one optical fiber and with at tube surrounding each and every optical fiber, especially made of plastic, comprising at least one string-like element; which can be pulled out, being added to the tube for easy access to each and every optical fiber. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a tube of an optical fiber cable according to the invention in a side view in perspective, 
     FIG. 2 shows a detail of the tube according to FIG. 1 in connection with a hook-like tool, 
     FIG. 3 shows a partial cross-section of the tube in FIG.  1 . 
     FIG. 4 shows a partial cross-section of the tube in FIG. 1 with fiber-like elements which have been pulled out. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 shows a tube  10  of the optical fiber cable according to the invention. In tube  10 , made from extruded plastic, several optical fibers not shown are arranged. The optical fibers can be loosely arranged in the tube or combined into a so-called ribbon. It is also possible for the optical fibers to be divided into several bundles, where each bundles has several optical fibers arranged loosely in a micro tube. In this case, several micro tubes, filled with optical fibers, are arranged in the tube. 
     It needs to be pointed out here, that several additional elements of the optical fiber cable are arranged around the tube. F. E. elements guaranteeing against water penetration, tension relief elements and an outer jacket can be arranged around the tube. Since the invention is independent of a particular cable type, these elements are not depicted in the drawing for the purpose of simplification. 
     According to FIG. 1, several string-like elements, which can be pulled out, are added to the tube  10 . These elements form a net-like or mesh-like system, which aid in the separation of so-called windows from tube  10 . Through them the optical fibers in tube  10  can be accessed without having to sever the optical fiber cable as such. 
     Two string-like elements  11  and  12 , which form the above mentioned net-like or mesh-like system, run approximately in the longitudinal direction of the tube. The remaining elements  13  of the mesh-like system—these elements will subsequently be called connecting elements—run approximately vertical or across, respectively, to the longitudinal direction of the tube  10 . These connecting elements  13  are connected to the elements  11 ,  12  in a type of net or ladder. 
     The elements  11 ,  12  and the connecting elements  13  are embedded or integrated, respectively, into a wall  14  of the tube  10 . Relative to this, FIGS. 3 and 4 especially show, that the net-like or mesh-like, respectively, ladder-like system is embedded in the wall  14  of tube  10  in such a way, that the distance of the elements  11 ,  12  and  13  from an inner surface  15  of tube  10  is smaller that the distance from the outer surface  16  of the same. Since FIGS. 3 and 4 depict a cross-section of the tube  10 , only the elements  11 ,  12  are visible in FIGS. 3 and 4. The elements  11 ,  12  and  13  are extruded into the wall. 
     If the elements  11 ,  12 ,  13  are pulled out or torn out, respectively, of the wall  14  of the tube  10  along its longitudinal direction, small windows are broken out of the wall  14  of the tube  10  each in the distance of the connecting elements  13 . According to the depth by which the elements  11 ,  12  and  13  are embedded in the wall  14  of the tube  10 , a corresponding remaining thickness of the wall  14  results, which can easily be separated without any additional tools by an installer. If the elements  11 ,  12  and  13  are embedded immediately adjacent to the inner surface  14  of the wall  14  of the tube  10 , it can happen that the wall is broken during pullout of the net-like system and the optical fibers are thus exposed. 
     According to an advantageous development of the invention, the elements  11 ,  12  and  13  are embedded into the wall  14  of the tube  10  with excess length. This means that the length of the connecting elements  13  is larger than the distance between the elements  11 ,  12  running in the longitudinal direction of the tube  10 , with which the connecting elements are connected. This results in a loop-like path of the connecting elements  13 . The elements  12  running in the longitudinal direction of the tube  10  are also embedded into the wall  14  with axial excess length. 
     The arrangement of the connecting elements  13  with excess length is especially important for easy separation or pulling out, respectively, of the net-like system of the elements  11 ,  12  and  13 . According to FIG. 2, the loop-like connecting elements  13  can easily be pulled out of the wall  14  with a hook-like tool. When this is done, the elements  11 ,  12  running in the longitudinal direction or axial direction, respectively, of the tube  10  can be severed and the net-like system can be torn out in the desired direction over the desired length without any additional tools. 
     Here it is noted, that the elements  11 ,  12  and  13  can also be embedded in the wall  14  of the tube  10  in such a way, that at least one segment of the connecting elements  13  sticks out of the outer surface  16  of the tube  10 . In this case, the loop-like running connecting elements  13  can be easily grabbed. 
     According to the invention, a net of elements  11 ,  12 ,  13  is therefore embedded into the wall  14  of the tube  10 , which can be broken out of the tube in a simple manner, in order to expose the optical fibers inserted into the tube  10 . This makes the optical fiber cable midspan accessible. The optical fibers can be accessed at any point of the optical fiber cable without destroying the optical fiber cable. The following advantages result: 
     For exposing the optical fibers, the optical fiber cable does not have to severed or cut totally. Therefore, tension relief elements in the optical fiber cable are not severed. The optical fibers, which are not necessary for the realization of a panel point, also do not have to be severed. Such an economical installation is possible within a shorter time frame. 
     The exposing of the optical fibers is possible without any special tool. After grabbing the elements  11 ,  12  or  13 , respectively, the net can be torn out of the tube by hand. 
     The optical fibers can be accessed at any point of the optical fiber cable. 
     The elements  11 ,  12  and  13  are preferably made from aramid and extruded into the wall  14  of the tube  10 . Especially the connecting elements  13  can easily be lifted out of the wall  14  by means of a hook-like tool. The system of the elements  11 ,  12  and  13  can then be torn out of the wall  14  in the longitudinal direction of the tube  10  by hand. Due to the ladder-like formation of the system of the elements  11 ,  12  and  13 , windows are broken out of the wall  13 . Depending on the depth of the embedding of the elements  11 ,  12  and  13  into the wall of the tube  10 , a corresponding remaining thickness of the wall  14  results. This is shown in FIG. 4 by means of notches  18 . At such standard break points, the remaining wall is easily severed and the optical fibers can be freed. 
     The invention is independent from any special cable type.