OPTICAL FIBER CABLING AND INSTALLATION METHOD THEREOF

Abstract

A method for making fiber optic cabling on buildings of various kinds; in particular, where the excavation of tracks to house the lines inside walls is problematic. The invention includes a wiring technique that allows a laying without prepared raceways. The optical cable can also be laid inside normal raceways. The optical cable can easily separate single fibers from bundles to facilitate the creation of networks, limiting as much as possible the number of joints. These objectives can be reached by using a cable consisting of a strip-shaped cable, in which a variable number of optical fibers are arranged side by side; and this strip-shaped cable is having side-by-side optical fibers comprised between two containment bands and are also immersed into a substance with lubricating properties. Moreover, the two containment bands also provide resistance to traction, and the external surface of the containment bands is adhesive.

Claims

1. An optical cable (100) in the form of a flattened strip, in which a variable number of optical fibers (110) for telecommunication are placed side by side, they are included between two containment tapes (130), they are also immersed in a substance with lubricating properties (120), and such strip-shaped optical cable (100) is characterized in that at least one of the outer surfaces of said strip-shaped optical cable (100) is adhesive, and said optical cable (100) is suited to be bent longitudinally, along directions parallel to said optical fibers (110) in correspondence of a zone where said containment tapes (130) are very close, so as to touch, or almost touch, and, when said optical cable (100) is folded, it is kept permanently folded for the effect of the adhesive face which remains inside the fold, and this folded configuration of said optical cable (100) is suitable for being inserted into a conduit.

2. The optical cable (100) according to claim 1 wherein said two containment tapes (130) are, at least partially, made of polypropylene.

3. The optical cable (100) according to claim 1 wherein said two containment tapes (130) comprise a texture made with a tensile-resistant filaments.

4. The optical cable (100) according to claim 3 wherein said texture is made with fiberglass filaments.

5. The optical cable (100) according to claim 1 wherein said substance with lubricating properties (120) is a gel or paraffin.

6. The optical cable (100) according to claim 1 wherein said optical fibers (110) for telecommunication, placed side by side, are separated by different distances, so that said optical cable (100) facilitates the longitudinal folding along directions defined by the areas of greater spacing between said optical fibers (110).

7. A method of installation of said optical cable (100), according to claim 1 comprising the following steps: a. defining an installation path between a generic point “A” and a generic point “B”; b. in the sections of said installation path, in which there is a conduit, bending said optical cable (100) longitudinally along one or more longitudinal directions and inserting it inside said conduit; c. in the sections in which no predisposition is present, maintaining said optical cable (100) in its flat and extended configuration, and making it to adhere to the surface where the installation must take place according to the path defined at step “a.”; d. in the installation zones included in the sections in which the optical cable (100) is laid in adherence to a surface, and therefore not inside a conduit, and in which the path of installation foresees abrupt changes of direction, or must follow sharp edges, the single optical fibers (110), contained in the optical cable (100), are freed by removing the containment tapes (130); e. said single optical fibers (110), once freed, are laid individually, adapting themselves to the type of path envisaged and maintaining adherence to the laying surface; f. in the sections in which said optical cable (100) is laid in adherence to a surface covering said optical cable with a generic thin covering layer which makes it substantially invisible.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] This invention also has further advantages, which will become more evident from the following description, from some examples of practical embodiments which illustrate further details, from the attached claims which form an integral part of the present description, and from the attached figures in which:

[0029] FIG. 1 schematically shows, in section, a typical implementation form of the optical cable realized according to the teachings of the present invention;

[0030] FIG. 2 schematically shows a portion of the optical cable as in the embodiment presented in FIG. 1, according to a view perpendicular to the plane defined by the strip which constitutes the cable itself;

[0031] FIG. 3 schematically shows a portion of the optical cable as in the embodiment presented in FIG. 2, in which it is shown a conformation that can be assumed by the optical cable realized according to the teachings of the present invention in order to change the direction in the pose;

[0032] FIGS. 4 (4a, 4b and 4c) show some possibilities of laying the optical cable according to the invention, so as to follow different paths;

[0033] FIG. 5 shows, in a schematic and sectional manner, the implementation form as in FIG. 1, in which a conformation that can be assumed by the optical cable realized according to the teachings of the present invention is highlighted, in order to be laid inside a duct;

[0034] FIG. 6 shows, schematically and in section, another typical embodiment of the optical cable realized according to the teachings of the present invention.

[0035] In all the proposed figures a simplified representation is offered, in which the proportions are not realistic. These are figures conceived essentially in order to highlight, each, some characteristic elements; therefore, many details, which do not concern the characteristics that we intend to describe, are omitted or represented in an approximate way.

DETAILED DESCRIPTION OF THE INVENTION

[0036] FIG. 1 shows a section view of said optical cable according to the teachings of the present invention. Number 100 indicates, as a whole, a typical embodiment of said optical cable according to the invention.

[0037] Number 110 indicates the actual optical fibers, in FIG. 1 there are shown six of them, but obviously it is possible to make cables with any number of fibers, depending of the needs. Said optical fibers 110 are coated, as usual, with a sheath indicated with the number 111. These sheaths 111, besides performing the protective function, generally also serve to distinguish the various fibers from one another, being normally of different colors. It is also important to underline how fiber optic cables are a technology that allows the creation of extremely thin cables: in fact, the diameter of a fiber optic cable for the applications here considered is of the order of a tenth of a millimeter, or even lower.

[0038] The representation of FIG. 1 shows a first characteristic of said optical cable 100, which consists in the fact that the various optical fibers which are settled in the cable are arranged side by side, and not grouped in a bunch as typically occurs in optical cables according to the known art.

[0039] With the number 130 two containment bands are then indicated; moreover, as shown in the figure, there is a space (which is intentionally wider than that of the actual embodiments, for reasons of explanatory clarity) between the bands 130 and the fibers 110. This space contains a lubricating substance indicated by the number 120. Said lubricating substance 120, typically, can be a gel, an oily substance, or simple paraffin, and has the main function of facilitating the flow of the fibers when the optical cable 100 is to be curved, or when a single fiber has to be partially unthreaded.

[0040] The presence of said lubricating substance 120, in which the individual optical fibers 110 are immersed, is of great importance since it allows to easily separate the individual fibers and to make them slide inside the cable 100. As will also be clarified with the help of FIG. 4, the possibility of individually managing the single fibers, for some traits, constitutes an essential prerogative of the optical cable 100 according to the invention, since it allows to overcome various installation problems, preserving the fundamental objective of avoiding digs to house the cable. Ultimately, said containment bands 130 perform a multiple function: they contain and protect the optical fibers 110, maintaining them in their side-by-side positions, they contain the lubricating substance 120 and they provide mechanical resistance to the cable structure.

[0041] Finally, the view proposed in FIG. 1 shows an area of the section in which the containment bands 130 are very close, so as to touch, or almost touch. This zone is designated by the number 101, it is typically formed along the central axis of the strip and, in this area, the fibers 110 are more spaced apart. The purpose of this zone 101 will be clarified in the following, in particular with the aid of FIG. 5.

[0042] FIG. 2 shows a different view of a portion of an optical cable 100 such as that shown in FIG. 1. In the proposed view, orthogonal to the plane determined by the bands 130, it can once again be appreciated the side-by-side arrangement of the optical fibers 110 and the surface of a band 130. Said bands 130 have, as already mentioned, a containment function, therefore, for their manufacture, plastic materials such as polypropylene are particularly suitable; material that can be worked into strips with a thickness even less than a tenth of a millimeter, which offers excellent flexibility and excellent containment performance. Moreover, another function of said bands 130 consists in conferring mechanical strength, and this function can be obtained by making a fiberglass weave. Also the fiberglass is a workable material in very thin filaments and, at the same time, extremely resistant to traction. Ultimately, although said bands 130 can be made by choosing from various materials, one of the preferable choices consists in using such polypropylene tapes with a fiberglass weave.

[0043] Definitely, a valuable feature of the optical wiring 100 is that it can be made in a shape that makes it extremely thin, with a thickness of a few tenths of a millimeter. Such a thin shape allows it to be laid directly on the surface of a wall, without the need to dig a trace, as is instead necessary for the laying of a raceway suitable for housing the passage of cables.

[0044] To facilitate installation, the optical wiring 100 is made by gluing at least one of its surfaces. In this way, the strip is made to adhere to the wall in a simple and immediate way.

[0045] The application can take place directly on the finished wall or, preferably, by lightly scraping the wall along the laying path so that the thickness, although very small, of the wiring does not protrude. Finally, to make the installation invisible, just cover the cable with a thin layer of plaster or paint. In this regard, it can be observed how the technologies for painting the walls today offer a wide variety of solutions, some of which involve the use of substances that can, or must, be applied creating a certain thickness. All these solutions can be particularly suitable for covering and concealing a wiring according to the teachings of the present invention.

[0046] Generally, the optical cables 100 according to the invention have both faces adhesive-coated: in fact, it can be useful that also the outer face is adhesive. This, not only to make it easier to cover the cable even with very thin layers of covering substances (in fact many covering substances adhere better to adhesive surfaces), but also, and above all, because when the laying involves changes of direction, normally it changes the face which must adhere to the wall.

[0047] FIG. 3 shows the conformation that the optical wiring 100 can assume in correspondence with a change of direction. A very simple way to realize a laying with a change of direction, in fact, consists in bending the strip which constitutes the optical wiring 100 along an oblique line with respect to the longitudinal axis of the strip itself. The direction of this bending line is shown in FIG. 3 with a dashed line indicated with the number 102. Depending on the inclination of said bending line 102, it is possible to obtain a variable angle of change of direction in the laying. For example, with a bending line 45° inclined to the strip axis, the laying direction forms a right angle. In general, the angle of change of the direction of the laying will be equal to 180° minus the double of the angle of inclination of the bending line with respect to the axis of the strip.

[0048] It is clear that after each bending, the side of the strip in contact with the laying wall changes, therefore it is advisable that both sides are adhesive-coated.

[0049] In a preferred implementation, in fact, both sides of the strip constituting an optical cable 100 are adhesive-coated, and covered by a thin protective film (as normally occurs to protect the adhesive surfaces) which is removed where it is necessary to stick somewhere or to adhere to some particular substance.

[0050] It is observed that the optical fibers have limitations on the curvature angle that is allowed for the transmission properties to be preserved. Therefore, the real fold cannot be performed with a “sharp” bending. This constraint on the fold imposes that, in correspondence with the changes of direction, the wiring 100 occupies a thickness significantly greater than twice the thickness of the laid wiring; this is because the two overlapping flaps cannot generally be crushed one on top of the other due to the bending, otherwise the fold would generate a “sharp” bending that would break the fibers.

[0051] However, this constraint can be easily managed without significantly compromising the advantages of the invention. In fact, it is enough to erode the laying wall more, but only for the points where the change of direction is made, so as to house the greater thickness.

[0052] Furthermore, this way of performing direction changes allows to manage the bending radius control with greater precision; in fact, all the individual fibers 110 that make up the optical wiring 100 are subject to the same bend (which can be controlled), which is not the case in cables where the individual fibers are bunched together.

[0053] Finally, the fact that individual fibers 110 are immersed in a lubricating substance, means that, in correspondence of bends, these are not subjected to torsion, i.e. another type of stress which is preferable to avoid in an optical fiber.

[0054] Therefore, even if only for the points of change of direction, the installation as shown in FIG. 3, although very simple and quick to perform, determines a thickness that requires excavation in the wall. Moreover, it subjects the optical fibers 110 to a curvature at the limits of the allowed radius, with risks of breakage, or with performance degradation. Well, the optical cable 100 according to the invention, thanks to its specific constitutive characteristics, is also suitable for a laying that preserves adherence to the laying surface with negligible thickness even at changes of direction, without the need for excavation. Moreover, this installation is able to follow complex paths that have sharp corners and edges, all without subjecting the fibers to curvatures that could cause problems. These laying methods are illustrated with the help of FIG. 4.

[0055] FIG. 4a shows a piece of optical cable 100, like the one shown in FIG. 2, in which the two containment bands (and obviously also the lubricating substance) have been removed along a short trait. This trait of optical cable is shown inside the area delimited by a dotted line, and it is indicated with the number 103. In the trait 103, therefore, the optical cable is made up of only optical fibers 110, which substantially maintain their side-by-side position since they are kept in this position by the overall structure of the optical cable 100 which, in the rest of its length continues to have the containment bands which confer it structure and compactness.

[0056] It is noted that the operation of releasing the optical fibers 110 along the short trait 103, is an operation made particularly easy by the fact that the optical fibers 110 are kept separate thanks to the particular shape of the optical cable 100 (for example, they are not interlaced). In fact, it is particularly simple, using suitable tools, to cut accurately the containment bands, without risking to damage to the optical fibers 110.

[0057] Once the optical fibers 110 have been released in the trait 103, for a sufficient length, it is possible to lay the optical cable as a whole, maintaining strict adherence to the surfaces to which it is applied, making it perform almost all the paths which may be required in a generic pose.

[0058] In FIG. 4b, an example of laying on a flat surface is shown, according to a path that requires a sudden change of direction. FIG. 4b shows how one of the optical fibers 110 can be curved in the trait 103, freed from the containment belts, without ever departing from the flat surface, assuming a very gentle curvature (thus avoiding any risk of damaging the fiber) and, at the same time determining a sharp change of direction.

[0059] Obviously, this kind of installation requires that the single fibers can be handled somehow independently, without being strictly enclosed in a single bunch: this is the main reason why, in correspondence with such changes of direction it is necessary to free the individual fibers, for a trait 103 of sufficient length, from the other elements which constitute the cable. Moreover, the presence of the lubricating substance 120 also allows, if it is necessary to adjust the length of the trait of free fibers, to let the individual fibers slide slightly off the part of the optical cable 100.

[0060] FIG. 4c shows another installation case that may present potential problems. It is the case of a pose that must follow a sharp edge determined by two incident planes: how can they be two walls, or a wall and a ceiling, or a wall and a floor. In this case too, the laying can be carried out by releasing the individual fibers 110 for a section 103. In this way, each individual fiber, lying on a first plane, can be curved until it runs, for a little bit, along the edge, and then continue laying on the second floor, curving gently until it reaches the desired direction.

[0061] In general, FIG. 4 show how the problem of following tortuous paths (with sharp changes in direction) can be solved, even using fibers having limitations on the radius of curvature. This can be done by posing directly the individual fibers along short stretches, in correspondence with the areas where changes of direction are required. Therefore, the optical cable 100, realized according to the teachings of the invention, has characteristics that facilitate the operation of freeing the individual fibers 110 for short stretches, removing the containment belts which keep the optical fibers 110 flattened, and benefiting from the effect of the lubricating substance that keeps the individual fibers well insulated and facilitates their sliding. This advantage is not trivial when compared to the installation in the duct. In fact, the ducts designed to accommodate fiber optic cables, in order to respect the curvature radius even at edges, must be housed on traces dug very deeply on the walls, making the laying operation very invasive.

[0062] The optical cable 100 according to the invention, on the other hand, is suitable for any type of installation, maintaining its fundamental prerogative which is that of being suitable for adhering above the laying surface. Moreover, since it is extremely thin, it can subsequently be covered and made invisible by means of a covering finishing layer, such as, for example, a suitable painting.

[0063] FIG. 5 shows a further configuration that can be assumed by the optical cable 100. The view proposed in FIG. 5 shows the same section of the optical wiring 100 proposed in FIG. 1 with the difference that the strip that constitutes the optical cable 100 is bent along a longitudinal direction. In this case, the fold does not affect the optical fibers 110, and is practiced in correspondence of the zone, indicated with the number 101, in which the two containment bands 130 are closer because they do not include (in that zone precisely) optical fibers.

[0064] The central zone of the strip which constitutes the optical cable 100, therefore, is arranged so that a fold can be easily made longitudinally. In FIG. 5, the number 104 indicates the angle formed by the two edges of the strip which constitutes the optical cable 100 when this is folded longitudinally as explained. In this case, the angle 104 may be closed, and the fold may also be very sharp, as it does not affect the optical fibers.

[0065] Taking advantage of the fact that the surface inside the angle 104, formed by the strip which constitutes the optical cable 100, when this is folded as explained, is adhesive, the optical cable 100 can remain permanently bent longitudinally and can be made more compact (no longer flat in the shape of a ribbon). In this new configuration it can easily be used as a normal cable, suitable to be passed inside traditional raceways.

[0066] Obviously, in the case of particularly wide optical cables, or with a greater number of fibers, this longitudinal folding operation can take place in more than one zone, with the aim of reaching a compact conformation suitable for being inserted in a raceway.

[0067] In a typical application, the optical cable 100 can be laid in its flattened shape for a more or less long distance, making it adhere to a wall, until it reaches a point (for example a box with switches) from which depart one or more raceways. From that point on, if necessary, the optical cable 100 can continue its laying inside a raceway, in its folded conformation as indicated in FIG. 5.

[0068] The two laying methods: [0069] a) laying inside a raceway, and [0070] b) flat laying in adherence on a surface,
they can be carried out in continuity, even alternating several times, without having to interrupt the optical cable, and provide for a junction where it ends the installation by direct application in adherence on the wall, and begins the laying inside the duct, or vice versa.

[0071] From what has been said so far, it therefore clearly emerges that the optical cable 100, according to the teachings of the present invention, defines a real laying method for installing a cable for data transmission on optical fiber, between a generic point “A” and another generic point “B”, positioned on a wall or on the floor, or on the ceiling of an generic environment.

[0072] First, this laying method foresee the identification of the path between point “A” and point “B”. As will also be clear from the following, the choice of the path does not present particular constraints and, in the most general case, this path is partly defined by existing ducts or channels, which can be used for the installation of the optical cable 100, and in part runs along paths not predisposed for laying the optical cable 100.

[0073] In this generic case, the installation takes place in the following way. [0074] In the sections in which a conduit or raceway is present, the optical cable 100 according to the teachings of the present invention is folded longitudinally (along one or more longitudinal guiding lines, depending on its width) and inserted inside said conduit or raceway. [0075] In the sections in which there is no provision, the optical cable 100 according to the teachings of the present invention is made to adhere, in its flat and extended configuration (which is also the configuration of minimum thickness) to the surface where the laying has to take place. [0076] In the laying areas where the optical cable 100 is laid in adherence to a surface, and therefore not inside a conduit or a raceway, and in which the laying path includes abrupt changes of direction, or must follow sharp edges, the individual optical fibers 110, contained in the optical cable 100, are freed by removing the containment bands 130, only to a limited extent to the trait 103 necessary to perform the aforementioned changes of direction. In this way, said individual optical fibers 110, so released, can be laid according to the indications previously illustrated with the aid of FIG. 4, and can be adapted to follow all the main types of path. [0077] In the sections in which the optical cable 100 is laid in adherence to a surface, this is then covered with a generic covering layer to make it invisible.

[0078] Typically, thin layers of plaster or various types of materials used for painting. Finally, it is reiterated that this laying method does not require that the optical cable 100 be sectioned, between the point “A” and the point “B”, in correspondence with the points where the type of laying changes, from laying in the duct to laying in adherence. Indeed, since typically the path sections in conduits terminate on special termination boxes, the point of the optical cable 100 in which the conformation changes, from flat to longitudinally folded, can easily remain housed inside such termination boxes.

[0079] The just described invention can then be proposed in many other variants; among these, for example, the variant presented in FIG. 6 is mentioned.

[0080] In the variant shown in FIG. 6 the individual fibers 110 appear to be more separate from each other and, above all, the two bands 130 wind them individually, approaching each other, almost touching one another, between each pair of adjacent fibers 110.

[0081] This variant represents a useful example to show how the strip composing the optical cable 100 can have various zones arranged for the longitudinal fold, and not only a central one, as indicated in FIGS. 1 and 5. Moreover, the areas of the strip in which the two containment bands 130 are closer, separating more clearly two contiguous optical fibers 110, are areas in which it is also facilitated to cut the strip longitudinally in order to separate the path of one or a group of fibers 110 from the others.

[0082] With respect to this latter need, to select one or more fibers 110 from the initial bouquet, it is observed that also the presence of the lubricating substance 120, in which the optical fibers 110 are immersed, further facilitates this operation.

[0083] Ultimately, compared to traditional optical cables, the optical cable 100 according to the teachings of the present invention, appears much more suitable to support the growing cabling needs that arise according to the more plausible evolutionary scenarios.

[0084] In summary, the present invention indicates a new technique that allows the laying of a wiring even in the absence of prepared raceways, without determining an aesthetic impact. At the same time, the optical cable 100 can also be passed inside the normal raceways that are still present in many sections. Furthermore, the optical cable 100 according to the teachings of the present invention can easily separate single fibers from bundles containing many, so as to facilitate the creation of networks with very varied and intricate topologies, limiting as much as possible the number of joints.

[0085] In general, then, the present invention lends itself to numerous variants while maintaining the claimed prerogatives. In fact, it can be developed in different sizes and including different amounts of optical fibers; and the invention itself can be carried out partially as some details described can be replaced by technically equivalent elements.

[0086] In particular, and as previously mentioned, the use of specific technologies and materials is not an essential part of the present invention. Therefore, if in the future the materials and adhesives sector were to make available new technologies, more advantageous than those mentioned in the preferred implementations, so as to implement the present invention more efficiently, further improvements could be made without thereby modifying the inventive nature and the principles that inspired the invention itself.

[0087] Other possible variants for the present invention may derive, in addition to the evolution of the technologies that constitute it, also from the evolution of the sector of optical components; so that the cables indicated in the invention could, for example, integrate components of varying complexity and also perform other functions, additional to the transmission function only.

[0088] Therefore, especially in the context of such evolutionary scenarios, the invention lends itself to incorporating and supporting further development and improvement efforts, capable of improving the performance of the system described. Therefore, many further developments can be made by the man skilled in the art without departing from the scope of the invention as it results from the present description and from the appended claims, which form an integral part of the present description; or, if these developments are not included in the present description, they can be the subject of further patent applications associated with the present invention, or dependent on it.