Patent Document

FIELD AND BACKGROUND OF THE INVENTION 
     The present invention relates to a communication cable having light-wave conductors and a jacket of high tensile strength, within a care of which and surrounded by the jacket, there is at least one ribbon line in which the light-wave conductors are held fast, extending parallel to each other between two ribbon-shaped supports (Federal Republic of Germany OS 28 15 514). 
     Light-wave conductors are finished structures of glass fibers which are suitable for the transmitting of light waves without additional treatment. Such light-wave conductors are used in communications engineering as a substitute for the previous customary metal conductors. They have a number of advantages over metal conductors. Light-wave conductors are very wide-band and low in attenuation so that more channels can be transmitted over a conductor with increased distance between repeaters. They can be readily bent and have small diameters so that the cross section of the cable can be reduced. Furthermore, they are not affected by external electric or magnetic fields. 
     For the use of light-wave conductors for transmission purposes in transmission engineering they must be worked into light-wave conductor cables. In this connection it must been noted that the light-wave conductors are not damaged either during manufacture or upon a transportation or laying of the light-wave conductor cable. Since they are brittle and have only slight extensibility it is necessary to proceed very carefully upon their manufacture. The light-wave conductors must, however, also be arranged in such protected manner in the light-wave conductor cable that their functionality is permanently assured. 
     In the known light-wave conductor cable according to the aforementioned Federal Republic of Germany OS 28 15 514, the light-wave conductors are combined in a pre-manufacturing stage into ribbon lines. The ribbon-shaped supports present protection for the light-wave conductors upon their further processing. At least one such ribbon line is embedded, in the case of this light-wave conductor cable, within a jacket which is developed as a profiled body with armoring wires. The ribbon line with the light-wave conductors is arranged loosely within a longitudinally extending bore in the profiled body. The ribbon lines used here have only a small number of light-wave conductors. Since only one ribbon line is to be arranged in each borehole of the profiled body, the number of light-wave conductors to be arranged in this known light-wave conductor cable is therefore very limited if the dimensions of the profiled body and thus the dimensions of the light-wave conductor cable are to remain within ordinary limits. The manufacture of this known light-wave conductor cable is furthermore very expensive since the ribbon line with the light-wave conductors must be pulled into the bore in the profiled body. This is possible only for relatively short lengths of cable. Furthermore, no information concerning the development of the ribbon-shaped supports for the ribbon line can be noted from the forgoing publication. These supports are evidently intended to serve only to hold the light-wave conductors together until they are introduced into the bore of the profiled body. 
     SUMMARY OF THE INVENTION 
     The object of the invention is to provide a light-wave conductor cable having light-wave conductors combined in a ribbon line and in which, with the smallest possible dimensions, a large number of light-wave conductors are arranged in a manner which is effectively protected. 
     This object is achieved in accordance with the invention in a light-wave conductor cable of the aforementioned type in the manner that the light-wave conductors are laminated between two ribbons provided on one side with an adhesive layer and bonded both to the light-wave conductors and to each other, their coefficient of thermal expansion corresponding to that of the light-wave conductors. 
     The advantage of ribbon lines is optimally utilized with this light-wave conductor cable. Within the ribbon line a plurality of light-wave conductors are arranged one alongside the other, in which connection they can thereby also be very simply connected with each other or connected to apparatus. This is true, in particular, if the light-wave conductors lie alongside of each other in a predetermined raster. 
     By lamination between the two ribbons, the light-wave conductors are furthermore held immovably over their entire length and furthermore protected well from moisture and from damage by bending or kinking. The composite unit consisting of two ribbons with the light-wave conductors lying between them imparts to the ribbon line the mechanical stability necessary for this. This stability is retained under all conditions to which a light-wave conductor cable is subjected. This applies, in particular, also to influences of temperature, which cannot have a negative effect because a material having a coefficient of thermal expansion corresponding to that of the light-wave conductors is used for the ribbons. Therefore no temperature-produced relative movements can take place between the light-wave conductors and the ribbons. In a preferred embodiment, the ribbons consist of a plastic which is reinforced by fiberglass. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     With the above and other objects and advantages in view, the present invention will become more clearly understood in connection with the detailed description of a preferred embodiment, when considered with the accompanying drawings, of which: 
     FIG. 1 is a cross section through a ribbon line for a light-wave conductor cable according to the invention. 
     FIGS. 2 to 6 are cross sections through different embodiments of the light-wave conductor cable. 
     FIG. 7 shows a light-wave conductor cable with layers successively removed. 
     FIG. 8 shows diagrammatically an apparatus for the manufacture of the light-wave conductor cable. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In the ribbon line 1 shown in FIG. 1 a number of light-wave conductors 2 are contained between two ribbons 3 and 4 which are provided on one side with a layer of adhesive. The adhesive layers of the ribbons 3 and 4 face each other upon the manufacture of the ribbon line 1 so that, upon lamination they are bonded to the light-wave conductors 2 and, in the intermediate spaces between them as well as at the edges, to each other. 
     As already mentioned, within the ribbon line 1 there are contained a number of light-wave conductors 2 all of which can be simultaneously connected to each other or connected to other apparatus by means of corresponding connecting elements or splicing devices. This is true, in particular, if the light-wave conductors 2 lie alongside of each other in a predetermined raster over the entire width of the ribbon line 1. For example, 10 to 60 light-wave conductors 2 can lie alongside of each other in a ribbon line 1. 
     The ribbons 3 and 4 consist of a material the temperature coefficient of which corresponds to that of the light-wave conductors 2. In that way, the result is obtained that variations in temperature do not have an effect on the ribbon line 1. In a preferred embodiment, any desired fiberglass reinforced plastic can be used as material for the ribbons 3 and 4. 
     If several ribbon lines 1 are to be arranged in a light-wave conductor cable, they can then be arranged one above the other in the manner shown in FIG. 2. However, it is also possible to arrange the ribbon lines 1 in random fashion within the cross section of the light-wave conductor cable, as shown in FIG. 3. In this case, they can also, as shown in FIG. 4, be curved around their longitudinal axis, whereby their flexibility as a whole is improved. 
     However, it is also possible to arrange within the core of the light-wave conductor cable only one ribbon line 1 the width of which is greater than the diameter of the cable 1. In order that the cross section in a light-wave conductor cable having such a wide ribbon line 1 can be filled up as well as possible, the ribbon line 1 is suitably curved. There are various possibilities for this: 
     As shown in FIG. 5, the ribbon line 1 can, for instance, be folded along its longitudinal direction so that an approximately circular or sinuous form results as envelope. In the embodiment shown in FIG. 6, the ribbon line 1 is curved around a core 5 in the form of open tube. This tubular structure has a slit 6 which extends in the longitudinal direction of the cable. This tubular structure is also preferably twisted around its longitudinal axis so that the slit 6 extends helically with a long lay. The core 5 can consist of any desired material within which, in principle, elements of high tensile strength can be arranged. However, it is also posible to arrange ordinary copper wires within the core 5, they being used for communication with traditional devices when a light-wave conductor cable is laid. The ribbon line 1 can also be wound around the core 5, as shown in FIG. 7 preferably with a loong lay. In this case the individual turns of the ribbon line 1 can overlap each other. 
     In all embodiments, the light-wave conductor cable has a jacket 20 of high tensile strength which can be applied by methods known from cable construction technique. The jacket 20 can, for instance, be a closed metal tube which is formed from a longitudinally entering ribbon and welded together with a longitudinal seam. Such a ribbon may consist, for instance, of steel. It is also possible to corrugate such a tube transverse to its longitudinal direction so as to impart greater bendability to it. The jacket 20 of high tensile strength can, however, also consist of thinner sheet-like metal ribbon which is stabilized by threads of high tensile strength. Such threads can, for instance, consist of steel or of polyaramide. In principle, the jacket 20 of high tensile strength may be of any desired construction. Assurance must be had that it can take up essential tensile forces such as may occur, for instance, upon the laying of the light-wave conductor cable. A layer of plastic can possibly be further provided over the jacket of high tensile strength. 
     For the manufacture of a light-wave conductor cable which contains at least one ribbon line 1 such as shown in FIG. 1, one may proceed for instance, as follows: 
     With reference to FIG. 8, light-wave conductors 2 are removed from a number of bobbins 8 corresponding to the desired number of light-wave conductors 2 and led to a pair of rolls 9. Ribbons 3 and 4 are furthermore introduced into the pair of rolls 9, the ribbons 3 and 4 being supplied from bobbins 10 and 11. The two ribbons 3 and 4 are brought up to the light-wave conductors 2 from different sides. By means of the pair of rolls 9, the light-wave conductors are laminated between the two ribbons 3 and 4 so that the final ribbon line 1 emerges from the pair of rolls 9. 
     In a following shaping device 12, the ribbon line 1 can be folded for instance in the manner shown in FIG. 2. Around the ribbon line 1, which has been folded in this way there is shaped, in a shaping stage 13, a metal ribbon 14 which is drawn off from a bobbin. From this there is produced the jacket 20 (FIGS. 2-6) of high tensile strength in accordance with the above embodiments. The jacket 20 can be welded with a longitudinal seam in a station 15. The station 15 can, however, also serve to bond a thin metal ribbon stabilized by threads of high tensile strength on an overlap place which extents in longitudinal direction. A layer of plastic can be applied by an extruder 16 in the same operation onto the jacket 20. The finished light-wave conductor cable 17 can then be wound on a bobbin 18. 
     The light-wave conductor cable 17 can, corresponding to the above remarks, therefore be produced in a single operation, including the manufacture of the ribbon line 1. In principle, however, it is also possible to procuce the ribbon line 1 in advance and introduce it only later on into a light-wave conductor cable. In particular, in the case of the last-mentioned manner of procedure it is also possible to arrange two or more ribbon lines 1 in one light-wave conductor cable. 
     The light-wave conductor cables 2 are protected not only mechanically but also against moisture by the laminating in the ribbon line 1. The light-wave conductor cable 17 can also be developed as a whole as moisture-protected and, in particular, as longitudinally water-tight if all cavities within the jacket 20 are filled with sealing material. Such a material can, for instance, be a petrojelly having a base of petroleum jelly which is customary in cable construction techique. In principle, however, foamable material can also be used.

Technology Category: 3