FR2564989A1 - Device for storing fibre-optic cables - Google Patents

Abstract

The invention relates to a device for storing opened-out fibre-optic cables permitting the individual splicing of the fibres which they comprise. The device 5 permits the storage of the fibre groups 28, 38 and, after opening them out, the storage of the now individual fibres 34, 41 as well as that of their respective splicing systems 33. The head 31, 39 for opening out each group can occupy a position which varies depending on the position of the anchoring point 30 of the strength member 29, which enables the length of individual fibre available for the splicing to be increased. Means 47 for fastening the fibre groups 48 render integral with the device the fibre groups outside the latter. The invention finds one application for connecting optical fibres, especially in the field of videocommunication systems.

Description

 The present invention relates to a device for storing optical fiber cables and, more particularly, a storing device for exploded optical fiber cables allowing individual splicing - or splicing - of the fibers which compose them.

 The video communications network makes extensive use of fiber optic cables to convey its information to user installations whose terminal service can only be carried out after appropriate cable distribution. The arbiter of this network is presented in the tree-like aspect and the hierarchical form that we already know, for example, in existing telephone networks. Thus, the same operating center can serve one or more centers distribution network thanks to a fiber-optic transport network, each distribution center serving terminal installations of user equipment geographically dispersed thanks to a fiber-optic distribution network and a cascade of burst points, the importance decreases with the proximity of the terminal facilities. It is therefore stated that, depending on their situation in the distribution network, the bursting points will have different capacities and, consequently, different aspects.

 Furthermore, it is obvious that the conditions under which interventions are carried out on the targets differ according to, among other things, the nature, the location, the access and handling facilities offered by the bursting point. However, it is important that these conditions are favorable to intervention personnel because the rao: orde, ent of fiber optic rears poses problems which did not exist with cables with metallic wires.

Indeed, these fibers have limited mechanical characteristics, so the curvatures imposed on them must never be less than a determined radius so that they retain good quality transmission characteristics. In addition, during the operations of connection, disconnection or reconnection of an optical fiber, one of the difficulties encountered lies in the risk of accidental breakage of the fiber, a risk that even today it is not yet possible to completely rule out . Besides, even apart from this risk, the fact remains that successive interventions on connected fibers or on defective splices generally lead to a new splicing process, which necessarily results in a reduction of the available length of the optical fiber. It is therefore advisable to keep in reserve a sufficient length of fiber to allow carrying out the necessary interventions and to remedy any breakages of fibers.

 However, this reserve is cumbersome, in particular when it is no longer only individual fibers but groups of protected fibers which, too, must have a sufficient reserve which it is desirable to store so that the intervention on a group of fibers is easy and involves only limited or even zero handling on the other groups of fibers.

 Consequently, the object of the intervention is a simple and economical device allowing the storage of the groups of optical fibers which it ensures the connection in a limited volume as well as, after their development, the storage of the fibers of these groups made individual, the housing of their reserve lengths and that of their respective splicing systems, this device having the advantage of allowing the spreading head to occupy a variable position with the result of an increase in the length of individual fiber usable for the splicing.

 For this beam, the invention provides a device of small thickness, which ensures the accommodation of the splicing systems, individual optical fibers and blooming heads of at least two groups of fibers to be connected end to end, heads of development whose position in the device is determined by that of the anchor point of the carrier of the corresponding group of fibers. Since the position of this anchor point is variable, we see that each development head can progress to the inside of the device - reducing the length of the group of fibers in reserve outside the device of the invention by the same amount - but thus making it possible to increase the length of individual fiber available for the splicing, while respecting the constraints of minimum curvature allowed by the optical fibers by reducing the distance separating the spreading head from the splicing systems. At least one of the edges of the device includes anchoring means ble of each of the groups of fibers of which it ensures the connection so that these groups of fibers are integral with the device when the latter is handled by intervention personnel but can also be easily dissociated from this same device.

The various objects and characteristics of the invention will emerge from the description which will now be given, by way of nonlimiting example, with reference to the appended figures which represent
- Figure 1, a schematic perspective view of the splice protection boot which provides accommodation for fiber optic cable storage devices according to the invention
- Figure 2, a side view, in section, of the splice protection boot of Figure 1 illustrating the reserve loves of a group of optical fibers associated with a storage device according to the invention
- Figure 3, a view of the device for storing groups of optical fibers according to the invention
- Figure 4, a view of the storage device, similar to that of Figure 3, wherein each group of optical fibers occupies an extreme position determining a maximum length and a minimum length for the corresponding individual optical fibers.

 We will begin the description by first referring to Figures 1 and 2 which relate to the external elements forming the environment of the storage device of the invention. The splice protection boot 1 can be of parallelepiped shape, consisting of two parts which are combined by appropriate means and known according to the dotted lines 2. The bottom 3 of this boot is secured to a support 4 in the form general of "T" on which come to be mounted, for example using grooves serving as slides for their edges, storage arrangements such as that shown in FIG. 1 and bearing the reference 5, this positive dls therefore being presented here in collective form for all the cards referenced 5 but which can be envisaged individually. Ports 6 are provided for 1 introduction of the cables coming from the underground pipes of the network; their different diameters allow the entry of cables of various capacities. As can be seen in Figure 2, each cable 7 is exploded - the inside of kicker 1- to release its groups of fibers 8, 9, 10 (or strands of fibers depending on the type of target 7) and each group of fibers (type of cable adopted in the example of the invention) is coiled in the case in the manner illustrated by the group of fibers S in order to constitute a reserve before arriving at the storage device 5 which is specific to it and that we will now call it more simply "card" in the following description. In a similar way, the group of fibers it -aftwr- dotted- describes its loves in shoemaking before reaching opening 12 where it can be grouped with other groups of fibers to constitute a cable which , outside of shoemaker 1, joins a pipeline in the underground network.

 We will now examine more specifically the card which is the subject of the invention with reference to FIG. 3. This card serves to house and protect a group of individual splices 13, protected optical fibers 14 and 15 which lead individually to a particular splicing element of group 13 and to the storage of any loves described by these fibers to constitute the reserve and respect the minimum curvature admitted by the fibers; it is also used for fixing the groups of protected fibers 16, 17, 18 according to features which allow the fixing point to have a variable position. It will be noted that the card is of rectangular shape, provided with a removable cover, of small thickness, this being determined in particular by that of the group of individual splices 13.

 The card comprises, in the part opposite to that where the group of individual splices 13 is mounted, openings 19 on one and other of the faces 20 and 21. After the groups of fibers 16, i7, 18 have been introduced in the card and that the development of their individual fibers 14 and 15 has been carried out, the development heads 22, 22 'and 23 release the carrier (s) 24, 24' and 25 from their respective fiber group .

The free end of each carrier is trapped by suitable screwing means 26-27 which, using an opening 19, locates the anchor point of the carrier, in other words determines the position of the corresponding development head in the card in relation to the cable entry of this. I1 therefore suffices to dismantle the fastening means 26 or 27, to use another opening 19 to modify the position of the development head concerned and, in particular, to introduce the corresponding group of fibers further into the card.

 Such an arrangement has an obvious advantage. Indeed, if the blooming points were in irremovable positions, when the loops of the individual fibers 14 or 15 would become too short to respect the minimum curvature allowed following, for example, successive interventions at the splicing of the fibers of the group 13, it would be necessary to pull the groups of fibers 16, 17, 18 towards the interior of the card, eliminate the existing blooming heads in order to redo new ones releasing the desired individual fiber lengths. above, if the loops of individual fibers 14 or 15 become too short, it is sufficient to change the anchorage point of the carrier of the corresponding group of fibers to give the individual fibers sufficient length so that they describe a radius compatible with their characteristics to be respected without modifying in any way the original development head.

 FIG. 4 illustrates what has just been explained, that is to say that one group of optical fibers is in the situation where the length of fibers available in the card is maximum while the other group of fibers has reached the position where this reserve length has become minimum, taking into account the curvature characteristics to be respected for optical fibers.

 If we consider the fiber group 28, we see that its carrier 29 is fixed to the anchor point 30, position inside the card 5 which is minimal for the fiber group 28 since it is the first anchoring point allowing the spreading head 31 to be housed in the card while being as close as possible to the edge of the cable entry 32.

In this situation, cn could have been provided - during the individual development of the fibers - a maximum length for the latter, making the best use of the space available in the card between the group of individual splices 33 and the development head. 31, as illustrated for example by the fiber 34, the reserve length of which can be further increased by optionally making it perform an additional love 35 before arriving at its individual group splicing element 33.

 We will now assume that following re-intervention, this length of fiber in reserve 34 becomes insufficient to maintain the minimum radius of curvature admissible by the fiber. Ordinarily, it would be necessary to pull the group of fibers 28 in the direction of arrow 36, eliminate the spreading head 31 and redo it further upstream to release a new length of individual fibers. Serious with the invention, this obligation. Indeed, we pull the group of fibers 28 in the direction of arrow 36 after having released the anchor point 30 of the carrier 29 but we keep the same blooming head 31 and it suffices to choose a new point anchor 37 suitable so that the individual fibers - such as fiber 34 - find a length compatible with the acceptable curvature.

 This is a situation of this kind illustrated by the group of fibers 38, it can be seen that its development head 39 has reached the maximum position inside the card 5 after having been pulled from the outside in the direction of the arrow 40, the individual optical fiber 41 having itself the minimum length compatible with the minimum acceptable hour for the fiber. We are therefore in the presence of one other extreme situation where, after having exhausted the reserve length of the optical fibers indXviduellesg they were nevertheless allowed to maintain an acceptable curvature by restoring the desired length between the group of individual splices 33 and the development head 39 by moving the latter and its anchoring point so that this the length of the protected fiber available in the card is increased at the expense of the length of the group of fibers coiled outside the card9 in the protective boot.

 It will be noted that provision has been made for guide pins - such as those referenced 42 or 43 - to serve to maintain the group of fibers 28 or 38 in its correct position. Furthermore, it is possible to equip between the group of individual splices 33 and the groups of fibers 287 38 a central core 44 whose rounded parts correspond to the minimum curvature admissible by the characteristics of the optical fibers; thus, it becomes impossible to perform individual splicing if the length of the fiber between the splicing point and the spreading head 39 no longer allows it to match the corresponding rounded part of the core 44.

 It was also noted that the anchor points of the carrier were constituted by discrete openings separated by predetermined distances. It goes without saying that this arrangement is in no way limiting and that the same result would be obtained with grooves made in the faces 20 and 21 of the card, grooves in which would slide the means for fixing the carriers of two groups of fibers 28 and 38.

 Finally, it should be noted - also returning to Figure 2- that each group of fibers has a reserve length outside the card 5 thanks to the loves as illustrated by the group of fibers 8 ( figure 2). However, it is necessary to accommodate these loves of fibers in the case 1 in the least cumbersome way possible while allowing the manipulation of a card 5 to act only on the groups of fibers related to this same card. To do this, in Figure 2, we see that the lower parts of the loves are housed between the card 5 and the wall 45 of the shoemaker 1 in the available space provided by the card holder.

In addition, the portion of fibers 46 adjacent to the card 5 can be made integral with the adjacent face thereof by any known fixing means.

Moreover, another example of securing the groups of fibers outside the cards is shown in FIG. 4: it can be seen that a edge of the card 5 comprises an element 47 which traps - but elastically - the group of fibers 8 in order to be able to handle it easily, release it from element 47 or re-introduce it there without having to dismantle this holding element. Although this does not appear in FIG. 4, since the card 5 uses two groups of fibers, it goes without saying that the element 47 can receive two groups of fibers such as 48, or else that another element 47 is also provided on the same edge of the card 5 to receive the other group of optical fibers. The advantage of these latter provisions is that, with one or more holding elements such as 47, it remains within the limits of the thickness of the card, that is to say that it does not overflow from the plumb with faces 20 and 21 (Figure 3).

 It is obvious that the description which has just been given has been given only by way of nonlimiting example and that other variants can be produced without departing from the scope of the invention.

Claims (7)

 1. Fiber optic cable storage device comprising at least one group of individual splice systems (13,33) ensuring the end-to-end connection of individual protected optical fibers (14, 15) coming from the blooming points (22 , 22 ', 23, 31, 39) of at least two elements (16, 17, 18, 28, 38) of optical fiber cables whose mechanical maintenance results from the fixing of the carrier (24, 241, 25, 29 ) in said storage device, the latter being characterized in that it comprises means (19, 26, 27, 30, 37) cooperating with the mechanical holding system of the elements (16, 17, 18, 28, 38 ) fiber optic cabals so that the position of the blooming point (229-22 '23, 31, 39) of these elements is variable inside said storage device, such an arrangement allowing -when the available length of individual protected fibers (14, 15, 34, 41) becomes too weak to respect the minimum bending allowed by the charac fiber characteristics- to increase the possible radius of curvature by moving the position of the point of outburst (22, 22 ', 23, 31, 39) so as to decrease the distance which separates it from the group of systems of individual splices (13, 33).  2. Fiber optic cable storage device according to the first claim, characterized in that none comprises, between the inputs of the elements (16, 17, 18, 28, 38) of optical fiber cables, openings ( 19, 37) used to house the fixing means (263 27) of the carriers (24, 24 ', 25, 29) of said elements (16, 17, 18, 28, 38) of optical fiber cables.  3. Fiber optic cable storage device according to the second claim, characterized in that it comprises several discrete openings (19, 37) disposed between the two element inlets (16, 17, 18, 28, 38 ) of optical fiber cables, these openings serving for the passage of the fastening screws of the carriers (24, 24 ', 25, 29).  4. Fiber optic cable storage device according to the second claim, characterized in that it comprises at least one continuous opening between the two inputs of elements (16, 17, 18, 28, 38) of cables to optical fibers, this opening cooperating with the fastening screws of the carriers (24, 24 ', 25, 29) to determine, on request, the position of these carriers between said inputs.  5. Fiber optic cable storage device according to the first claim, characterized in that it comprises, between the inputs of the elements (16, 17, 18, 283 38) of fiber optic cables and the heads of opening (22, 22 ", 23, 31, 39) of these same elements, guide means (42, 43) arranged substantially parallel to the openings (19, 37) used for fixing the carriers (24, 24 ', 25 , 29).  6. Fiber optic cable storage device according to the first claim, characterized in that it comprises, between the individual splicing systems (13, 33) and the elements (16, 17, 18, 28, 38 ) of optical fiber cables, at least one core (44) whose rounded parts determine the path of the individual protected optical fibers (14, 15, 41), these rounded parts corresponding to the minimum curvature allowed by the optical fibers.  7. Fiber optic cable storage device according to the first claim, characterized in that it comprises, externally, at least one element (47) for detachably holding at least one element (16, 17, 18, 28, 38) of optical fiber cables so as to associate with the storage device the elements of optical fiber cables which it provides for connection.