GB2314940A - Fibre strip for optical fibre, broad band, in-house cabling with adhesive - Google Patents

Abstract

A fibre strip 1 for optical fibre, broad band, in-house cabling has a carrier foil 3 with optical fibres 5 attached to one side 9 and an adhesive surface 13 on the other side 11. The optical fibres 5 and the carrier foil 3 are transparent. The optical fibres 5 may run parallel to each other and be combined into a strip 7 and laminated to the foil 3. A fibre 15 may be provided as a strain relief. The adhesive surface 13 may be covered by a removable protective foil. Also provided is an elongate deflection device 21 onto which the fibre strip 1 may be glued, having two longitudinal portions 25,27 twisted through 90 degrees and a bent interlying longitudinal portion 29.

Description

2314940 Fibre strip for optical-fibre. broad-band. in-house caWing

Background art

The invention relates to a fibre strip for optical-fibre. broad-band. inhouse cablmcy having a carrier foil and at least one optical fibre attached to one side of the carrier foil.

Optical fibres have meanwhile become generally established m optical mission technology. For instance. the use of glass-fibre cables is common in the field of wide-area networks. Although it would be desirable for the transmitted data to be relayed without conversion to an electrical transmission method optically as far as the end subscriber, up till now this has always proved impossible because of the excessively high costs.

Moreover, M the case of systems for distributing television signals, e.g. satellite community-antenna systems, as the number of television channels increases there is a demand for inexpensive and broad-band cabling techniques. In particular, the large transmission bandwidth of optical fibres makes fibre-optic transmission technology attractive in said field also. Here too, however, the costs are very high and the low-loss connection of optical fibres by means of a splicing technique contributes towards said high cost level.

For said reasons, in the field of public communications a coaxial or copper twowire technique is generally used in the subscriber area. Said techniques are also used for the in-house cabling of community antenna systems.

2 Advantages of the invention In contrast, the fibre strip according to the invention having the feature of claim 1 has the advantage that it may be laid inexpensively in the interior of buildings. Because both the carrier foil and the optical fibre are made of a transparent material, concealed installation for visual reasons is not necessary. Instead, they may be laid directly on the wall, ceiling or floor. Installation is simplified by the fact that the fibre strips have a self-adhesive surface facilitating fastening to a wall or ceiling. The use of additional installation materials is therefore extensively avoided.

There are preferably a plurality of parallel-runrang optical fibres provided on the carrier foil, said optical fibres in a preferred embodiment being combined into a strip and laminated onto the carrier foil. The result is therefore a very compact design of a transmission medium with a very large bandwidth.

There is preferably introduced into the carrier foil at least one fibre, which serves as a strain relief device and hence protects optical fibre and carrier foil from damage as a result of tensile loads.

Particularly easy handling of the fibre strip is achieved when the adhesive surface is self-adhesive and, prior to use, is preferably covered by a removable foil.

Since a fibre strip with a plurality of optical fibres is not flexible in its plane, a deflection device is provided. Said deflection device comprises an elongate body, onto which the fibre strip may be glued. In order to enable bending in the fibre strip plane, the deflection device comprises two portions, which are each twisted through 90' and enclose a portion which ensures the desired bending of the fibre strip.

Further embodiments and advantages of the invention are indicated in the remaining sub-claims and in the description.

Drawings There now follows a detailed description of an embodiment of the invention with reference to the drawings. The drawings show:

Figure 1 a diagrammatic sectional View of a fibre strip.

Figure 2 a diagrammatic view of a deflection device, and Figure 3 a diagrammatic view of a splice connector.

Embodiment Figure 1 shows a cross-sectional View of a fibre strip 1 which comprises a carrier foil 3 and a plurality of - m the present example, eight - parallel-rUnnMg optical fibres 5.

The optical fibres 5 are combined with the aid of a strip foil 7 into a bundle which is laminated onto a top surface 9 of the carrier foil 3, which is preferably made of plastic material.

A merely diagrammatically illustrated, self-adhesive coating 13 is applied preferably onto the full surface of an underside 11 of the carrier foil 3. It is, of course, also possible for the self-adhesive coating to be applied, for example, only at points so long as the desired adhesion remains guaranteed. To protect the adhesive surface, it is covered by a foil which is to be removed prior to application.

The glass fibres 5 serving as optical fibres comprise a fibre core, a primary coating and cladding. Preferably, both the carrier foil 3 and the glass fibres 5 are made of a transparent material to lend the entire fibre strip an unobtrusive appearance. To achieve said transparency, it is M particular necessary for the glass fibres 5 not to have a coloured secondary coating.

For strain relief purposes, fibres 15 made, for example, of nylon or another suitable material are worked into the strip foil 7. Said fibres run preferably parallel to the glass fibres 5 and, depending on the application, one fibre or a plurality of fibres 15 may be worked in.

The fibre strip 1 may then be installed particularly easily on walls by simply pressing the underside 11 of the carrier foil 3 onto the wall. The self-adhesive coating 13 then ensures that a secure and durable connection is achieved between wall and fibre strip 1. Said type of installation therefore does not require any additional material or tools. In particular, it is possible to dispense with concealed installation, which involves opening work with a chisel which is basically labourintensive and costly. Particularly in the case of retro- installation this is an important factor.

Because of the visual transparency of the fibre strip 1 and its very small dimensions (strip width, as a rule, less than 2 mm), the fibre strip 1 once stuck onto the wall is inconspicuous and so is not perceived as obtrusive. Installation is therefore conceivable not only in buildings but also in living areas. Furthermore, because of the small dimensions of a fibre strip 1, the drill holes necessary for installation are of a small diameter so that they too may be provided unobtrusively m living areas.

By virtue of the use of a flexible material for the carrier foil 3 3. during installation the entire fibre strip 1 is flexible as regards bending. the radius of curvature extending at right angles to the strip plane, and as regards torsion about the longitudinal axis. A bending of the fibre strip 1 in its plane is however impossible owing to the glass fibres being disposed parallel to one another.

Such bending is however possible when the fibre strip has two longitudinal twists. each through 90', and a curvature of the fibre strip portion thus bounded in the flexible curvature direction. Provided that the radii of curvature are selected in the region of a few millimetres, the optical losses occasioned by the curvature remain very low.

Figure 2 then shows a deflection device 21 having a top surface 2,35, onto which the fibre strip is glued. Said suitably shaped plastic part 21 serving as a deflection device makes it easier to comply with the desired radii of curvature and guarantees the necessary bending and torsion of the fibre strip 1.

The elongate plastic part 21 therefore comprises two portions 25 and 27, each of which is twisted longitudinally through 9T. Bounded by said two portions 25. 27 is a longitudinal portion 29 which lies at right angles to the initial plane of the fibre strip 1. The desired bending may then be achieved through deformation of said portion 29.

Like the fibre strip 1, the deflection device 21 is also made of a transparent material so that it too may be applied unobtrusively, e.g. onto walls.

6 When fibre strips 1 are used, for example, in community antenna systems, it is necessary in the region of a subscriber transfer point to separate individual fibres from the bundle of fibres available m the strip M order to make a connection to a fteher fibre segment leading to the end subscriber.

To said end, the fibre strip 1 is cut through at the desired point and the carrier foil 3 removed from a portion which is several centimetres long at the end of the strip. The free end of the fibre strip may then be prepared using known methods and connected to the likewise pre-treated end of the fibre bundle to be connected. To said end, an individual fibre is separated from the above-described, pre-treated fibre strip and connected with the aid of known methods (e.g. mechanical splices with a transparent plastic housing) to the ongoing fibre. The splice losses occasioned thereby may be limited to a maximum of 0. 1 dB per splice.

One possible way of inexpensively realizing spliced Joints between fibres is the use of a plastic part with a snap-in fibre-holding device, such as is shown in Figure 3.

For said purpose, the connection part 3 1 comprises a carrier 3 3 and a splice body 35, the splice body 35 serving as a fibre-holding device. The splice body 35 itself comprises two deformable flanks 37 which delimit a fibre receiver 39.

The splice body 35 is so designed that the fibre ends may be inserted in a longitudinal direction from above into the opening 39 of the splice body and with downward pressure surmount and finally snap into detents 41 formed in the flanks. The outer-lying part of the splice body, the diameter of which is adapted to the diameter of the fibre coating, then holds the fibre firmly at its coating and therefore serves as a strain relief device. The wall thicknesses of the deforniable flanks 37 of the splice body 35 have to be selected in such a way that, on the one 7 hand, the necessary deformation upon insertion of the fibres is achieved and, on the other hand, the retention force needed for precise alignment of the fibres is applied.

To avoid Fresnel reflection losses, the air gap between the end faces of the fibres is to be filled by introducing adhesive of a suitable refractive index which simultaneously serves as a further strain relief device. By virtue of the use of adhesive agents, e.g. so-called silanes, it is possible simultaneously to achieve greater adherence and a waterrepellent effect in the adhesive Joints. which is important for achieving a good resistance of the spliced Joint to climatic influences.

Claims (1)

1. Fibre strip for optical-fibre, broad-band, M-house cabling having a carrier foil (3) and one optical fibre (5) attached to one side (9) of the carrier foil (3), wherein the optical fibre (5) and the carrier foil (3) are made of a transparent material and the opposite side (11) of the carrier foil (3) to the optical fibre (5) comprises an adhesive surface (13).

2. Fibre strip according to claim 1, characterized in that a plurality of parallel-running optical fibres (5) are provided on the carrier foil (3).

3. Fibre strip according to claim 2, characterized in that the optical fibres (5) are combined into a strip (7) which is laminated onto the carrier foil (3). 1 4. Fibre strip according to one of the preceding claims, characterized in that at least one fibre serving as a strain relief device is provided in the carrier foil (3) and/or in the strip (7).

5. Fibre strip according to one of the preceding claims, characterized in that the adhesive surface (13) is self-adhesive.

6. Fibre strip according to one of the preceding claims, characterized in that the adhesive surface is covered by a protective foil which is removable.

9 7. Deflection device for a fibre strip according to one of claims 1 to 6.

which has an elongate foin- characterized in that a fibre strip may. be glued to one side, and that two Ion-itudinal portions of the deflection device are twisted through 90' and an interlying, longitudinal portion is bent.

8. Fibre strip substantially as herembefore described with reference to Figure 1 of the accompanying drawings.

9. Deflection device substantially as herembefore described with reference to Figure 2 of the accompanying drawings.