Surplus-length box for an optical fibre

The invention relates to a receptacle with a flat storage space and with a supply length of an optical line that can be pulled out or pushed in as required, the storage space being fixed by a core, by lateral guide walls firmly connected to it and extending orthogonally therefrom, and by the guide walls connected outer peripheral walls is formed, and wherein an outer end of the storage length wound around the core can be pulled out through an opening of the outer peripheral wall while reducing the winding diameter.

Such an arrangement is known from DE-A-32 48 003 and also from DE-A-27 21 300. Optical fibers are placed in loops with several turns. When one end is pulled out, there is a risk of the turns becoming jammed with one another, so that it is no longer possible to push them back in. The storage of ribbon cables, which consist of several firmly connected optical fibers, would also require high storage containers in accordance with the number of turns to be laid next to each other.

The invention has for its object to design the receiving device of the type mentioned in such a way that a jam-free pulling out and reinserting one end of an optical line, which can optionally be a ribbon line, is possible with an extremely flat construction.

The solution is achieved in that the distance between the guide walls is greater than the width of the optical line and less than 1.3 times this width, that the optical line is inserted into the storage space with turns running in a spiral in one plane, and that an opening leading out of the storage space is provided in the immediate vicinity of the peripheral surface of the core, through which the inner end of a spirally guided supply length of the optical line is led out of the storage space.

The spiral laying of the turns radially one above the other results in extremely flat containers. The turns are guided in a defined order. One end can be pulled out or pushed back in easily and jamming is impossible if the pull-out end is formed by the radially outer turn. Therefore, a large number of turns can be wrapped without problems. Even with small radial dimensions of the receiving device according to the invention, large storage lengths can be accommodated therein.

The diameter of the core should advantageously be greater than 40 mm, in particular greater than 50 mm, so that one end of the optical line does not fall below the permissible minimum bending radius even when the end of the optical line is completely pulled out.

An optimal utilization of the storage space results when the number n of turns<maths id="math0001" num=""><img file="EP0214701B1_D0001.tif" /></maths> is with<dl id="dl0001"><dt>d =</dt><dd>Diameter of the core,</dd><dt>D =</dt><dd>maximum diameter of the outermost turn</dd><dt>do =</dt><dd>Width of the optical line 0.2 &lt;k &lt;0.3, in particular k = 0.25.</dd></dl>

The change in diameter of the turns caused by pulling out or pushing in one end of the optical line is not impeded by the fixed end of the optical line which is to be led in from outside, if the fixed end of the optical line is from a plane outside the winding plane and radially outside starting obliquely to at least approximately to the peripheral surface of the core in a guide channel.

Such a guide channel is advantageously at least partially open to one of the flat sides of the receiving device, so that it can be manufactured easily and the end of the optical line can be inserted easily.

A preferred embodiment for inserting a ribbon cable is characterized in that the channel is rectangular in accordance with the cross-sectional dimensions of a ribbon cable and is set so that its wider side radially outside parallel to the direction of the winding plane and radially inside parallel to the outer surface of the core and this extends adjacent. This ensures that practically no increase in the receiving device is required for the permanently installed end, because this runs flat in the space required for the guide wall anyway. In addition, sharp bends are avoided. A subsequent turn is not already in the setting area of ​​the fixed end, but only when it runs in parallel to the outer surface of the core.

To form a stack, a plurality of receiving devices of the same type according to the invention can be arranged coaxially one above the other and can be connected by means of interlocking, possibly latching, elements.

It is not necessary for the lateral guide walls to be designed as closed flange surfaces. A preferred embodiment is characterized in that the guide walls consist, at least on one side, of at least 3 radially extending guide spokes which are separated in the middle area by insertion slots. The turns of the optical lines can be inserted through the slots. If these run obliquely to the tangent of the turns of the optical line, later accidental sliding out is prevented.

A further advantageous embodiment is characterized in that it has a central winding part which can be detachably inserted into an outer part which forms the outer peripheral walls and radially outer partial sections of the lateral guide walls.

The invention is explained in more detail with reference to the description of exemplary embodiments shown in the drawing.<dl id="dl0002"><dt>Figure 1</dt><dd>shows a two-part recording device according to the invention for storing several turns of a ribbon-shaped optical line</dd><dt>Figure 2</dt><dd>shows a cross section along the line AB through the embodiment of Figure 1</dd><dt>Figure 3</dt><dd>shows a one-story design similar to Figure 1, but with an insertion channel for the fixed end of the optical line</dd><dt>Figure 4</dt><dd>shows a cross section along the line CD of Figure 3</dd><dt>Figure 5</dt><dd>shows a typical application example for recording devices according to the invention</dd><dt>Figure 6</dt><dd>shows a cross section through the arrangement of Figure 5</dd><dt>Figure 7</dt><dd>shows a cross section through two stacked receiving devices</dd><dt>Figure 8</dt><dd>shows a further application example for the use of a recording device according to the invention.</dd></dl>

In the exemplary embodiments, receiving devices according to the invention are each shown for receiving flat band-shaped optical lines 1 to 5. Such ribbon cables consist of several individual optical fibers connected flat next to each other. The free height between the lateral guide walls, namely the closed rear walls 6 to 10 on the one hand and the front walls consisting of radial spokes 11 to 16 on the other hand, is then to be selected slightly larger than the width of the ribbon cables measured in the flat plane. It should not exceed 1.3 times this width, so that a smooth and orderly spiral guide is ensured.

However, if the receiving device according to the invention is to be used for storing round wires or individual optical fibers, the free height is slightly more than the diameter of the wires or lines.

The diameter of the cores 17 to 21 is 50 mm. In the case of direct contact with the core, the minimum bending radii of the innermost turn are certainly larger than the minimum permissible value for optical fibers.

The diameter D of the outer guide walls 22 to 26 is preferably 1.8 to 2.2 times the core diameter d. This ratio results in a good absorption capacity with relatively small external dimensions. The outer guide walls do not necessarily have to run cylindrically, but they can also consist of planar elements which abut one another at an angle, to which the outermost turn lies at points.

Given values ​​for D and d as well as for the diameter do of a round core or an optical waveguide or the thickness of a ribbon cable (smaller cross-sectional side), there is a maximum extendable length if the number n of turns is approximately<maths id="math0002" num=""><img file="EP0214701B1_D0002.tif" /></maths> is chosen with k = 0.25. However, values ​​of 0.2 &lt;k &lt;0.3 also lead to practical results.

In the embodiment shown in FIGS. 1 and 2, only 3 turns of the optical ribbon cable 1 are drawn for better illustration, which can be threaded through the insertion slots 27, which, as in the other figures, run obliquely to the tangential direction of the turns, so that an unintentional Slipping out of the inserted turns is prevented. However, if, as in the exemplary embodiment, the receiving device consists of detachably intermeshed parts, the winding part 28 and the outer part 29, the windings can also be wound around the core 17 of the winding part 28 in a simple manner before the two parts are joined together. The fixed part of the ribbon cable 1 leading to the inner turn is freely guided between the contact on the circumference of the core 17 and the radially outer holder 30. In this area, the cross-sectional plane of the ribbon cable 1 twists by 90^O from a position directed flat to the plane of the guide walls into a position parallel to the peripheral surface 17. It cannot be completely ruled out that the section of the ribbon cable 1 guided freely over the windings lies against the windings underneath and hinders their sliding. If, as in the exemplary embodiments, radial spokes 11 serve as guide walls, between which large areas remain open, so that the windings are accessible, any jams can be easily released.

In particular, if several of the receiving devices according to the invention according to FIG. 7 are to be stacked on one another, an embodiment according to FIGS. 3 and 4 is recommended. This is drawn in one piece, but can of course be composed of several individual parts. The ribbon cable 2 is introduced through the oblique slots 31 of the spoke-like guide walls 12. In contrast to the embodiment which is similar in principle according to FIGS. 1 and 2, the fixed end 32 of the ribbon cable 2 is guided in an insertion channel to the exit point 33. It initially runs flat through a downwardly open groove 34 of the guide wall 7 and enters near the peripheral surface of the core 18 into the receiving space between the guide walls 7 and 12. It then runs steadily up to the angle of 90^O rotating at the point 33, through a groove 35 in the core 18 which is open towards the side of the walls 12. Therefore, the end 32 cannot obstruct the spiral windings, since it is through walls of the insertion channel consisting of the grooves 34 and 35 against contact with the following Is shielded. When shaping the channel 35, care must be taken that the minimum permissible bending radius of the optical waveguide is not exceeded at any point. The course of the setting is determined in a predetermined manner.

A typical area of ​​application for receiving devices according to the invention is a connecting sleeve according to FIG. 5, of which only one housing plate 36 is designated. The reserve length of the first ribbon cable 3 is accommodated in the receiving device 37, that of the ribbon cable 4 in the similar recording device 38. For the convenient production of the splices 39, the stored reserve lengths can first be pulled out and pushed back into the receiving device after the splices have been completed.

In FIG. 7, in the event that instead of a ribbon cable 4 fewer optical fibers containing and accordingly narrower ribbon cables are fed, two stacked receiving devices are shown, each with receiving spaces adapted to the narrower widths of the individual ribbon cables.

FIG. 8 shows an end termination for a ribbon cable 5. The reserve lengths required for making the connections of the individual optical fibers 40 with plug-in elements 41 are stored in the receiving device 43.