GB2461567A

GB2461567A - Hybrid optical fibre jacket comprising pulling jacket and ruggedized jacket

Info

Publication number: GB2461567A
Application number: GB0812261A
Authority: GB
Inventors: Kristof Vastmans
Original assignee: Tyco Electronics Raychem BVBA
Current assignee: Commscope Connectivity Belgium BVBA
Priority date: 2008-07-04
Filing date: 2008-07-04
Publication date: 2010-01-06
Also published as: GB0812261D0

Abstract

An optical fibre cable 1230 with a hybrid cable jacket comprises a ruggedized cable jacket section 1300 (e.g. a jacket to provide open environment protection suitable as a drop cable) and a pulling jacket cable section 1320 (e.g. a jacket suitable for fibre pulling into a building such as a riser cable) and a coupling 1310 operable to couple said ruggedized cable jacket section with said pulling cable jacket section to protect optical fibres 1260A-F. The method of coupling the jackets to produce a hybrid jacket is also specified.

Description

AN OPTICAL FIBRE CABLE HAVING A HYBRID CABLE JACKET

FIELD OF THE INVENTION

The present invention relates to an optical fibre cable having a hybrid cable jacket and a method.

BACKGROUND OF THE INVENTION

In a fibre optic network, fibres are typically routed from a central office of a service provider via distribution boxes and into a multiple dwelling unit distribution box. The fibres are then routed from the multiple dwelling unit distribution box to individual dwellings within the building. The fibres are typically provided within a cable jacket to protect the fibres from damage. Whilst different cable jackets exist, they each have their own shortfalls.

Accordingly, it is desired to provide an improved cable jacket.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention there is provided an optical fibre cable having a hybrid cable jacket, comprising: a ruggedised cable jacket section; a pulling cable jacket section; and a coupling operable to couple the ruggedised cable jacket section with the pulling cable jacket section, the ruggedised and pulling cable jacket sections being operable provide protection to at least one fibre to be routed.

The first aspect recognises that the environmental conditions and constraints within a multiple dwelling unit can vary enormously to the extent that a cable jacket which has characteristics suited to conditions in one part of the multiple dwelling unit or building, may be unsuited or disadvantageous under conditions found in another part of the multiple dwelling unit or building. For example, the region between a multiple dwelling unit distribution box and a riser is generally exposed and may be subject to a high probability of mechanical impact. Also, the cable may need to be routed around many obstacles. Accordingly, it would be preferable to provide a cable jacket having ruggedised characteristics which enable the fibres to be safely routed within that environment. However, such a ruggedised cable jacket is generally unsuitable for the congested, but comparatively less hostile, environment of a riser. For the riser environment, the cable jacket section would benefit from characteristics which enable the jacket section to readily be pulled through this congested environment.

Accordingly, there is provided an optical fibre cable having a hybrid cable jacket having two sections. The Iwo sections are coupled together. One of the sections is ruggedised and the other section is suited to pulling. The section of the hybrid cable jacket which is ruggedised may be utilised in the more hostile environment of, for example, the region between a multiple dwelling unit distribution box and a riser, whereas the section suited to pulling may be utilised within the riser. It will be appreciated that this hybrid approach provides a cable jacket having properties suited to the different environments within which the single run of fibres needs to be routed.

In one embodiment, the ruggedised cable jacket section is configured to provide an improved mechanical protection to the at least one fibre than the pulling cable jacket section. Hence, the ruggedised section is more robust than the pulling section. This provides for enhanced protection of the fibre in an open environment. However, this degree of mechanical protection is not necessary within the riser. By not providing a high degree of mechanical protection within the riser, a more compact cable jacket may be utilised in that congested environment.

In one embodiment, the ruggedised cable jacket section is configured to provide an improved resistance to displacement under a diametric force than the pulling cable jacket section. Accordingly, the ruggedised section is able to resist forces which if applied to the pulling section would cause the pulling section to displace into typically an oval shape. This helps to protect the fibres within the ruggedised section from impacts within that environment, whilst allowing the pulling section to displace more readily when being routed through a congested region within a riser.

In one embodiment, the ruggedised cable jacket section is configured to provide a substantially constant internal diameter when bent. Accordingly, the ruggedised section provides a substantially unchanging internal diameter in order to avoid unnecessarily tight bends being applied to the fibres.

In one embodiment, the pulling cable jacket section is configured to provide a reduced external surface friction than the ruggedised cable jacket section. Hence, the pulling section may more readily be routed through the congested region of a riser due to its relatively low surface friction, such low friction is not required for the ruggedised section.

In one embodiment, the pulling cable jacket section is configured to bend with a smaller bend radius than the ruggedised cable jacket section. Hence, the pulling section may more readily be bent when being routed in order to circumvent obstruction within the riser environment.

In one embodiment, the pulling cable jacket section is configured to provide a reduced external diameter than the ruggedised cable jacket section. Hence, the volume occupied by the cable within the riser environment is minimised thereby reducing the space occupied within the riser and enabling the cable to be routed in situations which would otherwise not be possible with a larger cable.

In one embodiment, the pulling cable jacket section is configured to provide a higher fibre filling rate than the ruggedised cable jacket section. Accordingly, the packing density of the fibres within the pulling cable jacket is higher than in the ruggedised cable jacket. Providing a lower filling rate enables the fibres in the ruggedised cable jacket to be routed within this jacket section more easily. For a predetermined number of fibres, it will be appreciated that fibre filling rate affects the diameter of the cable jacket.

In one embodiment, the pulling cable jacket section is arranged to extend within at least a portion of the ruggedised cable jacket section. Accordingly, in situations where the external diameter of the pulling section is such that it may be fitted within the infernal diameter of the ruggedised section, the pulling section may be extended info the ruggedised section for a pre-determined distance in order to help improved the coupling between the two jacket sections.

In one embodiment, the coupling comprises a mechanical coupling operable to retain the ruggedised cable jacket section in a fixed relationship with the pulling cable jacket section. Accordingly, the coupling causes the two sections to be fixed together, thereby preventing their inadvertent separation.

In one embodiment, the mechanical coupling is operable to align the ruggedised cable jacket section with the pulling cable jacket section. Hence, the coupling aligns the two sections to assist with movement of any fibres through the hybrid cable jacket.

In one embodiment, the mechanical coupling is configured to provide an internal diameter which transitions between an internal diameter of the ruggedised cable jacket section and the pulling cable jacket section. Hence, any difference in diameter between the sections of the hybrid cable is accommodated by the coupling to help assist any movement of any fibres within the hybrid jacket.

In one embodiment, at least one of the ruggedised cable jacket section and the pulling cable jacket section comprises a low smoke zero halogen polyethylene.

In one embodiment, the hybrid cable jacket comprises the at least one fibre, the at least one fibre comprising a bend-optimised fibre having a polyamide coating.

In one embodiment, the hybrid cable jacket is a multiple dwelling unit riser cable jacket.

In one embodiment, the optical fibre cable is installed in a multiple dwelling unit with the ruggedised cable jacket section extending in a lower part of the multiple dwelling unit, and the pulling cable jacket section extending from the lower part in a cable riser duct of the multiple dwelling unit.

According, to a second aspect of the present invention there is provided a method of producing an optical fibre cable having a hybrid cable jacket, comprising the steps of: providing a ruggedised cable jacket section; providing a pulling cable jacket section; and coupling the ruggedised cable jacket section with the pulling cable jacket section.

In embodiments, the method comprises method steps corresponding to features of the first aspect.

Further particular and preferred aspects of the present invention are set out in the accompanying independent and dependent claims. Features of the dependent claims may be combined with features of the independent claims as appropriate, and in combinations other than those explicitly set out in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will now be described, with reference to the accompanying drawings, in which: Figure 1 illustrates a cable distribution arrangement; Figure 2 illustrates an arrangement of an optical cable; Figure 3 illustrates an arrangement of a multiple dwelling unit building distributor; Figure 4 illustrates an optical fibre cable having a hybrid cable according to one embodiment; and Figure 5 illustrates an optical fibre cable having a hybrid cable according to another embodiment.

DESCRIPTION OF THE EMBODIMENI

Figure 1 illustrates a cable distribution arrangement 1000. A central office 1010 associated with a service provider is coupled with a distribution point 1020 by an outside service provider cable 1015. Distribution point 1020 may be coupled with further distributions points (not shown) using outside service provider distribution cables 1023 and 1027. The distribution point 1020 couples with one or more multiple dwelling units 1030, 1040, 1050, using an outside service provider distribution cable 1025. The outside service provider distribution cable 1025 loops through each multiple dwelling unit 1030, 1040, 1050 in turn. The outside service provider distribution cable 1025 may also loop through further multiple dwelling units (not shown). It will be appreciated that the multiple dwelling units may be residential, commercial or industrial buildings. In this way, it can be seen that the service provider couples via an optical network with the multiple dwelling units 1030, 1040, 1050. Details of how the outside service provider distribution cable 1025 is then utilised within the multiple dwelling units 1030, 1040, 1050 are described below, with reference to Figure 3.

Figure 2 illustrates a typical arrangement of an optical cable 1100, such as would be * utilised for the outside service provider cable 1015, the outside service provider distribution cables 1023, 1025, 1027, or for cables utilised within the multiple dwelling units 1030, 1040, 1050. The cable 1100 comprises an ouferjacket 1110 which provides for appropriate environmental protection of the cable 1100. Disposed within the cable jacket 1110 is a plurality of tubes 1120. Within the tubes 1120 are provided one or more individual fibres 1130. Typically 16 or 32 individual fibres 1130 may be provided within a single tube 1120. Also a braided Kevlar (registered trade mark) strand (not shown) may be provided within cable 1100 which may be mechanically coupled with a pulling tool to assist in routing the cable.

Figure 3 illustrates an arrangement of a multiple dwelling unit building distributor 1210 for dwelling unit 1030 according to one embodiment. In the example shown in Figure 3, the multiple dwelling unit 1030 comprises a single dwelling unit 1200A-1200F on each floor. However, it will be appreciated that more than one dwelling unit may be provided on each floor of the building. The other multiple dwelling units 1040, 1050 will generally have a similar general layout, although the number of floors and the number of dwelling units on each floor may vary from multiple dwelling unit to multiple dwelling unit.

The multiple dwelling unit building distributor 1210 receives the outside surface provider distribution cable 1025. One or more fibres 1130 from the outside service provider distribution cable 1025 are pulled from the outside service provider distribution cable 1025 and typically coupled with a splitter 1220. It will be appreciated that more than one splitter unit 1220 maybe provided and that more than one fibre 1130 may be extracted from the outside service provider distribution cable 1025, according to the needs of the multiple dwelling unit 1030. The splitter 1220 takes a single fibre 1130 and couples this fibre, typically using splicing techniques, with a plurality N of pigtail cables 1225. The plurality of pigtail cables 1225 are provided to a patching arrangement 1230 which enables the plurality of pigtails 1225 to be selectively coupled with a riser cable 1230 comprising a plurality M of fibres which leaves the multiple dwelling unit building distributor 1210.

The riser cable 1230 is routed through a building region 1240 to a riser 1250. The building region 1240 may be, for example. a basement area of the multiple dwelling unit 1030.

The riser cable 1230 may be surface mounted in the building region 1240.

The riser 1250 will typically be a service conduit within the multiple dwelling unit 1030 extending from the basement to the under-roof region of the building. The riser 1250 will therefore extend between the floors of the multiple dwelling unit 1030.

Within each dwelling unit]200A-1200F, one or more fibres 1260A-1260F may be pulled from the riser cable 1230 in order to provide connectivity within the individual dwelling units 1200A-1200F. User equipment 1270A may then couple with the assodated fibres 1260, as required.

It will be appreciated that arrangement enables user equipment within individual dwelling units to be coupled via the optical network with the service providers. Also, the presence of the patch arrangement 1230 within the multiple dwelling unit building distributor 1210 enables connectivity with different service providers to be achieved.

Figure 4 illustrates in more detail the riser cable 1230 according to one embodiment.

The riser cable 1230 comprises a plurality of individual fibres 1 260A to 1 260F in addition to other fibres not current allocated to a dwelling unit housed within a hybrid cable jacket. The hybrid cable jacket has a ruggedised cable jacket section 1300 coupled using a coupling 1310 with a pulling cable jacket section 1320.

The ruggedised cable jacket section 1300 provides for improved mechanical protection and restraint of the fibres than that of the pulling cable jacket section 1320.

The ruggedised cable jacket section 1300 is utilised in the region 1240 between the multiple dwelling unit distribution box 1210 and the riser 1250. This region 1240 is typically within a basement area where the riser cable 1230 needs to be routed around many objects and may even be surface mounted. Accordingly, the ruggedised cable jacket section 1300 needs to be very robust to be able to withstand any inadvertent impacts that may occur to the cable in this region either due to the ruggedised cable jacket section 1300 being snagged or due to impacts on the ruggedised cable jacket section 1300 during installation when, for example, fixing cable clips. According, the ruggedised cable jacket section 1300 is made of high resilience material which has a high resistance to impact. Furthermore, the thickness of the ruggedised cable jacket section wall is relatively large when compared with that of the pulling cable jacket section 1320. Likewise, the external diameter of the ruggedised cable jacket section 1300 is relatively large when compared with that of the pulling cable jacket section 1320 in order to be consistent with other cabling which may be being routed so that the same cable clips or other retention devices may be used to fix the cable jacket section 1300. The internal diameter of the ruggedised cable jacket section 1300 will generally be larger than the internal diameter of the pulling cable jacket section 1320 to enable a lower filling rate within the ruggedised cable jacket section 1300 to be achieved. The filling rate is indicative of the space occupied by the fibres within the cable jacket. A ruggedised cable jacket section 1300 having a filling rate of less than 30% is preferable (i.e. of the total internal cross-sectional area of the ruggedised cable jacket section 1300, less than 30% of that area is occupied by fibres; a filling rate of 0% indicates no fibres within the jacket section, whilst a filling rate of 100% is the notional maximum achievable if it were possible to completely fill the jacket section). A 30% filling rate provides for a relatively low packing density of the fibres within the ruggedised cable jacket section 1300, which increases ease of routing. The filling rate of the pulling cable jacket section 1320 will generally be higher than that of the ruggedised cable jacket section 1300 to provide for a reduced diameter.

The region 1240 may also have a number of obstacles which require the ruggedised cable jacket section 1300 to be routed with a number of directional changes in order to circumvent those obstacles. Accordingly, the constructions of the ruggedised cable jacket section 1300 prevents sharp changes in direction and ensures comparatively large bend radii in order avoid unnecessary optical losses despite the minimum bend radius of a fibre not being exceeded. This also helps to reduce potential failures due to fatigue. Typically, the ruggedised cable jacket section 1300 comprises an articulated low smoke, zero halogen, polyethylene arrangement. The articulation enables the ruggedised cable jacket section 1300 to bend, whilst controlling the minimum bend radius achievable and ensuring that the internal diameter of the ruggedised cable jacket section does not substantially decrease during such bending. This substantially constant internal diameter also helps to reduce friction on the fibres as they are pulled through the ruggedised cable jacket section 1300. Of course, the ruggedised cable jacket section 1300 may be of a differing detailed arrangement, provided it provides adequate protection for the fibres in the region 1240.

The pulling cable jacket section 1320 provides for improved flexibility for the fibres than that provided by the ruggedised cable jacket section 1300. The pulling cable jacket section 1320 is utilised in the riser 1250. This riser 1250 is typically a service duct or conduit which extends from the ground floor or basement region of the multiple dwelling unit 1030, between all the floors of the building, typically to the roof area. The riser 1250 will also be utilised by other utilities serving the individual dwelling units within the building and so is typicafly highly congested with other pipe work or cabling.

Accordingly, the pulling cable jacket section 1320 is highly flexible and compact to be able to be threaded or routed through the existing utilities within the riser 1250.

Accordingly, the pulling cable jacket section 1320 is made of material which is highly flexible. Furthermore, the thickness of the pulling cable jacket section 1320 is as small as possible. Likewise, the external diameter of the pulling cable jacket section 1320 is small in order to provide a compact arrangement. This compact arrangement enables the riser cable 1230 to occupy a minimised volume within the riser 1250 and enables the riser cable 1230 to fit through small gaps within the riser 1250. The flexibility of the pulling cable jacket section 1320 also enables relatively tight bends to be achieved within the riser 1250 in order circumvent obstacles. Furthermore, the external surface of the pulling cable jacket section 1320 has a relatively low surface friction coefficient, either due to the selection of a low friction material, the addition of a low friction coating to the outer surface of the pulling cable jacket section 1320 or by the introduction of a lubricant during routing. This reduced surface friction further assists with the routing of the cable through the congested riser 1250. Of course, the pulling cable jacket section 1320 may be of a differing detailed arrangement, provided it provides flexibility for the fibres in the riser 1250.

The ruggedised cable jacket section 1300 is coupled with the pulling cable jacket section 1320 using a coupling device 1310. In the arrangement shown in Figure 4, the relative dimensions of the ruggedised cable jacket section 1300 and the pulling cable jacket section 1320 are such that the external diameter of the pulling cable jacket section fits within the internal diameter of the ruggedised cable jacket section 1300.

Accordingly, the pulling cable jacket section 1320 is inserted a small distance into the ruggedised cable jacket section 1300 and the connector 1310 is applied. The connector 1310 will generally clamp or hold the two cable jacket sections and prevent axial displacement. Alternatively, the connector 1310 may be simply a housing into which an adhesive applied which, once set, retains the two cable jacket sections together.

Figure 5 shows an alternative embodiment of a riser cable 1230'. The riser cable 1230' comprises a ruggedised cable jacket section 1300 coupled using a coupling 1310' with a pulling cable jacket section 1320'. The relative diameters of the ruggedised cable jacket section 1300' to the pulling cable jacket section 1320' are large. Therefore, the ruggedised cable jacket section 1300' has a significantly larger diameter than the pulling cable jacket section 1310'. Accordingly, the two cable jacket sections are spaced apart and axially aligned by the coupling 1310'. The coupling 1310' is provided with a transition section 1330 which extends between the internal diameters of the two cable jacket sections. This transition section 1330 assists in guiding individual fibres 1 260A-1 260F when being introduced into the hybrid cable jacket.

The fibres 1260A-1260F are bend-optimised fibres having a polyamide coating.

Hence, an optical fibre cable having a hybrid cable jacket is provided which consists of a compact flexible pipe construction for use in the riser 1250 and a less compact, more rigid cable construction for routing elsewhere. The fibre type is preferably classified G 657 A-B or beyond. The transition between the two cable jackets is achieved by mechanical anchoring (such as by cold or heat shrink) in such a way that the fibres can be moved within the cable without damage. In the riser environment, the cable needs to be of very small size, compact, have high flexibility, have low flammability and a low friction coefficient to guarantee compatibility in this congested environment. In the region 1240, rigidness is more important than size. Typically, the multiple dwelling unit distribution box 1210 is positioned far away from the riser 1250 and so many uncontrolled bends around corners may be required to route between the multiple dwelling unit distribution box 1210 and the riser 1250.

The hybrid cable construction makes it possible to combine multiple cable construction properties and application properties for both environments. The hybrid cable jacket enables fibres to be pulled from the multiple dwelling unit distribution box 1210 towards the dwelling units even if this distribution box 1210 is placed with many 90° bends between it and the riser 1250. Also, fibres can readily be pulled from above through the hybrid cable.

Although illustrative embodiments of the invention have been disclosed in detail herein, wit h reference to the accompanying drawings, it is understood that the invention is not limited to the precise embodiments shown and that various changes and modifications can be effected therein by one skilled in the art without departing from the scope of the invention as defined by the appended claims and their equivalents.

Claims

CLAIMS1. An optical fibre cable having a hybrid cable jacket, comprising: a ruggedised cable jacket section; a pulling cable jacket section; and a coupling operable to couple said ruggedised cable jacket section with said pulling cable jacket section. the ruggedised and pulling cable jacket sections being operable provide protection to at least one fibre to be routed.
2. The optical fibre cable of claim 1, wherein said ruggedised cable jacket section is configured to provide an improved mechanical protection to said at least one fibre than said pulling cable jacket section.
3. The optical fibre cable of claim 1 012, wherein said ruggedised cable jacket section is configured to provide an improved resistance to displacement under a diametric force than said pulling cable jacket section.
4. The optical fibre cable of any preceding claim, wherein said ruggedised cable jacket section is configured to provide a substantially constant internal diameter when bent.
5. The optical fibre cable of any preceding claim, wherein said pulling cable jacket section is configured to provide a reduced external surface friction than said ruggedised cable jacket section.
6. The optical fibre cable of any preceding claim, wherein said pulling cable jacket section is configured to bend with a smaller bend radius than said ruggedised cable jacket section.
7. The optical fibre cable of any preceding claim, wherein said pulling cable jacket section is configured to provide a reduced external diameter than said ruggedised cable jacket section.
8. The optical fibre cable of any preceding claim, wherein said pulling cable jacket section is configured to provide a higher fibre filling rate than said ruggedised cable jacket section.
9. The optical fibre cable of claim 7 or 8, wherein said pulling cable jacket section is arranged to extend within at least a portion of said ruggedised cable jacket section.
10. The optical fibre cable of any preceding claim, wherein said coupling comprises a mechanical coupling operable to retain said ruggedised cable jacket section in a fixed relationship with said pulling cable jacket section.
I L The optical fibre cable of any preceding claim, wherein said mechanical coupling is operable to align said ruggedised cable jacket section with said pulling cable jacket section.
12. The optical fibre cable of any preceding claim, wherein said mechanical coupling is configured to provide an internal diameter which transitions between an internal diameter of said ruggedised cable jacket section and said pulling cable jacket section.
13. The optical fibre cable of any preceding claim, wherein at least one of said ruggedised cable jacket section and said pulling cable jacket section comprises a low smoke zero halogen polyethylene.
14. The optical fibre cable of any preceding claim, comprising: said at least one fibre, said at least one fibre comprising a bend-optimised fibre having a polyamide coating.
15. The optical fibre cable of any preceding claim, wherein the hybrid cable jacket is a multiple dwelling unit riser cable jacket.
16. The optical fibre cable of claim 15 installed in a multiple dwelling unit with said ruggedised cable jacket section extending in a lower part of said multiple dwelling unit, and the pulling cable jacket section extending from said lower part in a cable riser duct of said multiple dwelling unit.
17. A method of producing an optical fibre cable having a hybrid cable jacket, comprising the steps of: providing a ruggedised cable jacket section; providing a pulling cable jacket section; and coupling said ruggedised cable jacket section with said pulling cable jacket section.
18. An optical fibre cable as hereinbefore described with reference to the accompanying drawings.
19. A method of producing an optical fibre cable having a hybrid cable jacket as hereinbef ore described with reference to the accompanying drawings.