It is frequently now the case that new buildings require an infrastructure of ducting to receive optic fibres for communications purposes. Because optic fibres are relatively expensive, the relatively inexpensive ducting is usually installed without the fibres in place.

When a specific requirement is realised, the fibres are blown down the relevant ducts to appear at their intended location. This presupposes that the ducting is fully mapped and labelled.

The ducting comprises microducts of a few millimetres diameter bundled with other microducts into a sheathed duct. The sheath can have various degrees of environmental protection. The sheathed ducts may themselves be contained in larger ducts, at least as the network approaches a central communications room, for example.

Each microduct is capable of having optic fibres or other cables blown into them. When requirements change, existing cables or fibres can be withdrawn and upgraded or different fibres inserted in their place. At the end of each microduct a connector is needed if it is to connect to a blowing machine, or to another length of microduct, or to a connection terminal of a junction box.

The connector needs to be of a type which has a gripping function, to securely locate on the end of the microduct, and a seal, to prevent escape of gas pressure in the

microduct when the fibre is being blown into it. Such connectors exist and overlap the end of the microduct.

In a communications room of a large building, there may be hundreds of microducts. Managing those ducts is a problem. In a sheath, each microduct is usually colour coded and, within a cable, individually numbered. Being round, the microducts adopt a regular formation inside the sheath. That formation is consistent throughout the length of the sheath. However, not all the microducts will necessarily be different colours. But since their position is consistent, and they are individually numbered, identifying which duct is which is possible.

The problem arises, however, when the sheathing is stripped back to expose a reasonable length of microduct (usually perhaps about one metre length). This is sufficient to permit easy working with the microduct when connecting it to a blowing machine or to a junction box.

But, under these circumstances it is more difficult to trace a microduct back to its original position in the sheath and identification becomes a problem. In any event, managing a large number of stripped back microducts in a confined communications room is a problem, particularly if the numbers on the individual ducts become obliterated or illegible, which can often be the case.

The solution is to provide a connector plug on the end of the sheath and in which connectors are already in place and so that the entire sheath and all its microducts can be connected en bloc to a junction box, which may incorporate a patch system. Then, within the junction box, different microducts from one cable plugged into the box can be patched to further cables also plugged into box. Indeed, in the communications room

where cables terminate at such a plug in a junction box, bulkhead or the like, a blowing machine can be connected to individual microducts to blow optic fibres up that cable, and through intervening junction boxes, to finally appear at their intended location. In fact, it is possible, although not usually preferred, to blow fibres the other way from their final destination back to the junction box in the communications room. It is also common that such cabling may exit buildings to connect with external underground chambers, street cabinets or other buildings. In any event, having each cable terminated with a plug that can be mated in a socket of a junction box or the like is desirable in the management of the individual microducts.

But how to connect such a plug to the end of a sheath is a difficulty, which it is an object of the present invention to overcome. Connection of the plug needs to be capable of being effected in the field, rather than in the factory. This is because the sheaths need to be cut to length once they are installed.

Therefore the system must be simple and straightforward to implement and must ensure that each connector location in the plug is occupied by the appropriate microduct so that identification is assured.

In accordance with the present invention, there is provided a connector plug for a sheathed assembly of microducts that have a fixed formation in the assembly, the plug comprising a cone sleeve and a divider guide body, wherein: the cone sleeve comprises a coned tubular element whose smaller end is formed into a polygonal shape to confine microducts inserted through the sleeve to a fixed

positional formation that relates to the formation they have in the assembly; and the divider guide body comprises passages smoothly transitioning between a rear end and a front end of the body, the passages opening at the rear end of the body in said positional formation, and at the front end the passages open in a spaced relationship permitting connectors to overlap their ends; so that assembly of the connector on an assembly can be effected by: stripping back a sheath thereof to expose microducts; sliding on the cone sleeve over the exposed microducts to orientate the microducts into said positional formation ; and pushing on the divider guide body so that the microducts enter the openings of the passages in the rear end of the body.

Preferably, said positional formation is a polygonal formation, being one that circular section microducts naturally adopt when pressed together, based on the triangular formation of three juxtaposed circles.

However, when encased in a circular sleeve, a central duct may be surrounded by a hexagonal arrangement of six ducts, but twelve surrounding ones do not continue the hexagonal arrangement. Instead, when confined within a circular sleeve, they arrange themselves in a twelve- sided formation that has a slightly smaller maximum diameter. Nevertheless, the relative positions of the microducts remains the same, except that in transforming between the dodecanol and hexagonal arrangements there is a rotation of 15° of the outside layer of microducts, relative to the inside layers, about the centre microduct. Accordingly, it does make a difference as to

which direction the rotation takes place and it is for this reason that an index is preferably provided in the cable that physically distinguishes between the two rotation directions. Indeed, the index may force rotation in just one direction. In a twenty-four duct cable that is currently employed in some applications a central duct of appropriate diameter is provided with nine surrounding ducts in an inner layer touching each other and the central duct, and fifteen further surrounding ducts in an outer layer. Here, the index locates the microducts of the inner layer with respect to the outer layer.

A connector plug constructed in this way therefore permits ready assembly in the field while at the same time ensuring that each microduct is led to a specific position in the plug so that each can be reliably identified and accurate connections to it can be made.

Preferably, said positional formation is rotationally symmetrical about an axis parallel the passages. Accordingly, it is also very much preferred, in this circumstance, that the connector plug is for an assembly of microducts provided with an index as described above and so as to permit rotational orientation of the assembly, the connector plug further comprising a key for said index and a keyway in said cone sleeve which both orientates the sleeve with respect to the index and the sleeve with respect to the body.

Therefore, rotational orientation of the assembly with respect to the plug can be assured. Moreover, the index not only orientates the assembly generally, but serves to locate the rotational position of microduct layers within the assembly.

Indeed, the present invention provides a novel microduct assembly comprising an assembly of microducts in fixed formation in a sheath and an index identifying the rotational orientation of the assembly, wherein said index comprises a plurality of adjacent microducts connected together as a single shared conduit, elongate in cross-section.

The key is then shaped to permit insertion in said conduit with a specific orientation with respect thereto, a key tooth of the key being adapted to extend parallel the assembly outside of said formation and fit in said keyway of the sleeve. Such an arrangement ensures that it is only with the index that the key can be associated.

Preferably, said microducts are arranged in encircling layers, and said index orientates the layers with respect to one another. This ensures that each microduct can be identified at each end of the assembly.

Said index microducts may be a microduct in a radially outermost layer of the assembly and radially inwardly adjacent microducts in inner layers of the assembly.

One preferred assembly in accordance with the invention comprises an assembly of nineteen circular section microducts, in the form of a single central microduct, six surrounding microducts in hexagonal formation in an inner layer, and twelve surrounding microducts in a dodecanol formation in an outer layer, said index comprising an adjacent pair of microducts, one from each layer.

Another preferred assembly in accordance with the invention comprises an assembly of N1 circular section

microducts, in the form of a single central microduct, an inner layer of N2 microducts, all touching the central microduct and each microduct touching adjacent ones in the inner layer, and an outer layer of N3 surrounding microducts, said index comprising an adjacent pair of microducts, one from each layer. Preferably, N1, N2 and N3 are twenty-five, nine and fifteen respectively.

Preferably, at least the microducts of the inner and outer layers are of the same external diameter.

Thus, in another aspect, the present invention provides a combination of a sheathed assembly of microducts as defined above and a connector plug as defined above.

In yet another aspect, the invention provides a method of joining a sheathed assembly of microducts as defined above to a connector plug as defined above comprising the steps of: a) stripping sheath from the end of the assembly to expose loose microducts; b) sliding on the cone sleeve over the exposed microducts to orientate the microducts into the positional formation that relates to the formation they have in the sheath; and c) pushing on the divider guide body so that the microducts enter the openings of the passages in the rear end of the body.

The rear end of the divider body preferably has points formed between the openings of the passages adapted to be inserted into the gaps between adjacent microducts and to guide the microducts into their respective passages.

The divider body is preferably formed by layers, between adjacent ones of which said passages are formed.

Where the microduct assembly comprises seven or nineteen microducts in hexagonal formation, the divider body comprises four or six body layers, respectively.

In each case, the middle two body layers define between them passages that remain in a plane of intersection between the body layers, which plane is parallel the axis of the coned sleeve. Outer body layers outside said middle body layers define, either with the middle body layers or, in the case of a nineteen microduct assembly, with intermediate body layers, inclined passages departing from said plane away from the rear end of the body.

In each case, with the exception of passages lying in a plane perpendicular said intersection plane, the passages on either side of said perpendicular plane depart from said plane away from the rear end of the body.

The passages preferably open into parallel, spaced ports at said front end of the body. Connectors may be captured in said ports, each comprising a sleeve fitting having a seal and a directional grip, whereby microducts can be inserted into the fitting and be sealed thereto by the seal, withdrawal thereof being prevented by said grip.

A face plate having apertures sized to receive microducts, but to prevent passage of the connectors, may be located in front of said front end, said apertures being positioned to coincide with said ports.

Preferably, the face plate is fixed to said front end, for example by screws.

The body and sleeve are preferably captured, once they have been assembled on the end of an assembly of microducts, between clamshell housing parts. Preferably, the housing parts are capable of ultrasonically being welded together and optionally to the body and/or sleeve.

Alternatively, mating connection elements may be provided by which the housing parts can be interconnected, for example by screws. Preferably, the clamshell housing extends beyond the coned sleeve so that it can overlap the end of the sheath on the microduct assembly.

Preferably, a ring end cap is snapped into engagement with the clamshell housing, and is adapted to lock around the housing around the sheath of the microduct assembly and press a ring seal in the end cap between the housing and sheath.

The coned sleeve is preferably substantially circular at its widest end and of corresponding diameter to the sheath on the assembly of microducts. In this event, when assembly is commenced, the sheath of the microduct assembly is stripped back only so far as to permit the sleeve to abut the sheath end with a relief gap between the sleeve and the body when the body is fully inserted onto the microducts so that the microducts are all received within their connectors in their ports and the clamshell housing is located about the body and sleeve.

Where the index comprises said joined microducts having a shared conduit, the passage for said index is correspondingly elongate in section and is formed between middle layers. Said index passage therefore lies in said intersection plane.

An embodiment of the invention is further described, hereinafter, by way of example, with reference to the accompanying drawings, in which: Figures la, b and c are respectively, an end view of an assembly of microducts, a perspective view of the assembly of microducts in the initial stages of assembly of a plug connector in accordance with the present invention, and a perspective view of a key for use with the plug connector of Figure lb ; Figure 2 is an exploded view of the guide body, some microduct connectors, and an end face plate of the plug connector in accordance with the present invention; Figures 3a to e are perspective views similar to Figure 1b showing further stages of assembly of the plug connector ; and Figure 4 is a schematic layout of microduct cabling in a building and employing connector plugs in accordance with the present invention.

In the drawings, a microduct assembly 10 comprises 19 microducts 12 sheathed by a cover 12 (shown only partially in Figure la). In the sheath, the microducts are formed into a dodecanol configuration as shown at A in Figure la. A dodecanol formation has a smaller maximum diameter DA than the diameter DB of the hexagonal alternative configuration shown at B.

Throughout their length, the microducts 12 are sheathed with the protective cover 14. They are sheathed so that the relative orientation of each microduct 12 remains the same along the entire length of the sheath 14. The microducts 12 are colour-coded, but not necessarily all with different colours. On the other

hand, they are individually numbered (at least within each colour) so that precise identification is possible.

Despite that, in a junction box bringing together a number of different cables of microducts, it may be difficult to locate and identify the different microducts once they have been stripped of their protective sheaths.

This difficulty is illustrated in the schematic representation of a possible microduct cable layout shown in Figure 4.

Here, individual computer or other communication apparatus terminals 101 each have an optic fibre link 102. One or several optic fibres may be encased in a single microduct 104, but ultimately all the optic fibres for a particular area A join in a junction box 106 where a thin cable 110 of perhaps four or seven microducts terminates. The cables 110 from a larger area B of a building (for example an entire floor of a building) are fed to an intermediate junction box 120. On the ends of the cables 110 are plugs 122 (of the type described further below and in accordance with the present invention) that plug directly into sockets 124 provided in the wall 126 of the junction box 120. Large microduct bundled cables 130 have perhaps 19 or 24 or more microducts, and these are likewise terminated in plugs 132, similar to, but larger than, the plugs 122. These are likewise received in larger sockets 134 in the box 120. Internally of the box 120, microduct links 140 join each terminal of the sockets 124 with one terminal of the sockets 134. This may be done in the factory to ensure precise mapping.

The cables 130 from area B of the building are fed through the building to a large connection box 150 located in a communications room of the building.

Ducting 152 from the connection box may provide links to other buildings or to an external communications network, possibly including external underground chambers or street cabinets, and possibly using more microduct cabling of the type described above, including connector plugs and sockets, as required. Optic fibres 154 serving the building are terminated at equipment 156. So also are optic fibres 158 fed through the microduct cables 130,110 to a particular terminal 101.

When a terminal 101 is newly required to have an optic fibre, a blowing machine 160 is connected by a microduct 162 to the appropriate microduct terminal 135 of the appropriate socket 134. The machine 160 blows an optic fibre 164 up the duct 162, through the socket 134 and into the cable 130. It passes through one of the links 140 in the junction box 120 and exits through one of the cables 110 to finally emanate at the terminal 101.

The optic fibre 164 is provided on a reel 166, or a pan (not shown) to supply the blowing machine 160. When the fibre reaches the terminal 101, it is cut from the machine 160 and spliced into the equipment 156. In the absence of the connector plugs 122,132 in accordance with the invention, and their associated sockets 124,134 in junction boxes in the building, management of all the microducts and cables is problematic, even when they are all individually identifiable.

Referring back to Figure la, the microducts 12 in any cable can be distinguished from the others by virtue of their position in the formation A. However, since this formation is rotationally symmetrical about its axis 18, an index 20 is provided. In this example, the index 20 comprises a lobed conduit 24, which effectively occupies the position of two microducts 12. Thus the

duct 24 has a single elongate conduit 22. As illustrated, the index 20 is arranged at the outside of the assembly in a radial orientation. This is explained further below, but is because, when the sheath 14 is removed, the assembly is arranged in the hexagonal formation B and this requires rotation of the outside layer Lo of microducts with respect to the inside layer LI through an angle of 15°. However, the layers can rotate in either direction with respect to each other and consequently, tying a microduct from each layer together, as is effectively done with the index microduct 20 that bridges both layers Lo, LI, the relative angular position of the two layers is assured.

A use to which the sheath 14 of microducts 12 is put is to provide routes for optic fibres in a building when specific communication requirements are identified, as described above with reference to Figure 4. The ducting is therefore laid in a building as it is constructed with numerous sheathed cables 14 (130,110 in Figure 4) being distributed to various points of the building. Some terminate in junction boxes 120 where they join with larger cables that ultimately terminate back in a communications room. However, until a particular communications requirement is identified for any particular area of a building, no further infrastructure is required. Each microconduit 12 is terminated in the connector plugs 122,132 with a connector that permits connection to the blowing machine 160. An individual microduct connector 26 is shown in Figure 2, but no further detail is given of this conventional device other than that it comprises a sleeve incorporating a seal. It also has gripping means so that, when a microduct is inserted in the connector 26, firstly a seal is effected

between the connector and microduct, and secondly the gripping means grips the microduct preventing its withdrawal from the connector.

As described above, when a microduct is identified in a sheath 14 as requiring optic fibre insertion, the present invention suggests terminating the entire sheath with a plug connector 100 (122,132 in Figure 4). The plug terminates each microduct 12 with a connector 26 enabling the entire plug to be inserted in a socket of a junction box and any microduct to be selected for feeding with an optic fibre.

The cable assembly 14 is shown in the drawings with 19 microducts 12 (or 17 if the index 20 is excluded), but smaller assemblies of 7 microducts are also possible with a smaller cable. Obviously, other formations are also possible with any number of microducts. For example, another form may comprise 24 microducts in two layers of 15 and 9 surrounding an enlarged central duct. Again, a radially adjacent pair of microducts may be supplanted by an index microduct 20 to rotationally orientate the ducts with respect to their central axis, as well as between layers.

When the cable 14 that requires a plug 100 has been identified, its sheath is stripped back a specific length as described further below. In the example illustrated, this is 180mm. A key 30, as shown in Figure lc, is first inserted into the index duct 20. The key 30 has a body 34 having a profile corresponding with the shape of the index 20. A key tooth 32 lies adjacent the body with a gap 3 between them equal to the thickness of the wall of the index microduct 20. The loose ends of the assembly of microducts 12 are collected together in a roughly

circular formation, corresponding with the formation they have in the sheath. A cone sleeve 33 is then inserted over the end of the assembly.

The coned sleeve 32 has an enlarged end 36 and an hexagonal end section 38. A keyway 400 is formed down one side of the sleeve 32. If the sleeve 32 is able to slide all the way to the sheath 14, over the key tooth 32, then two facts can be deduced from this. Firstly, that the microducts passing through the hexagonal end 38 of the coned sleeve 32 will have the same relative disposition with respect to one another as they have in the sheath 14. There will be the rotation of 15° referred to above, but this will serve merely to bring the index radial, rather than inclined to the radial.

The second is that the keyway 400 will be aligned with the index 20. Consequently the microducts will be positioned appropriately for insertion in the plug 100.

Turning to Figure 2, the plug 100 further comprises a guide body or block 40, which is shown exploded in the drawing. The guide body 40 has a number of layers 42a, b, c and 44a, b, c. When assembled together, the layers 42,44 form passages 46 between a front face 48 and a rear face 50 of the guide body 40.

In Figure 3a, the layers 42,44 are shown assembled, with the exception of top layer 42c, which is missing.

When assembled, a series of openings are defined in the rear face 48 by the passages formed by mating grooves 46 on the facing sides of the respective layers. A series of points 52 are formed between the openings. These are not easily visible in the drawings (except see Figure 2).

When the assembly of microducts 12 is offered to the rear face 48 of a guide block 40, the points 52 fit into

the triangular spaces 56 (see Figure la) between adjacent microducts. These points then guide each microduct into its respective opening and passage 46. When each enters its respective passage, the guide block 40 is further pressed onto the ends of the microducts 12 so that the ducts progress along their respective passages. At the same time the sleeve 32 is manoeuvred back until its rear end 36 abuts the sheathing 14.

With reference to Figure 2, as well as forming the passages 46, the layers 42,44 also form ports 58 adapted to receive microduct connectors 26. Each port has one connector 26 and these are kept in place by an end face plate 60 secured to the front of the guide body 40, for example by screws. The face plate 60 has apertures 62 corresponding to the ports 58. However, these apertures 62 are of smaller diameter than the connectors 26, which are thereby locked in position. However, the apertures 62 are sufficiently large to accommodate optic fibres inserted from the other side, for example by a blowing machine.

The rear ends of the layers 42 are stepped so as to form slots 64 in the face 48, which again serve to facilitate insertion of the microducts into the passages 46. However, the slot 64a between the two middle layers 42a, 44a also has the function of permitting entry of the head 5 of key 30. This measure ensures that the guide body 50 is correctly in orientated with respect to the assembly of microducts 12 and the cone sleeve 33.

Furthermore, the passage 46a adapted to receive the index 20 is shaped accordingly. Likewise, the port 58a and the corresponding aperture 62a, are also shaped in the same manner. Indeed, when the key 30 reaches the aperture

62a, it can be withdrawn therefrom so that use can be made of the index conduit 24.

Figure 3b shows three microconduits 12a lying in their respective passages 46 (bear in mind that layer 40c is not shown in Figure 3b). The microconduits 12a are shown inserted in connectors 26. In this view, the front end of the guide block 40 including the ports 48 is missing. However, in Figure 3c, not only is the guide body 40 complete with regard to its layers, it is also shown with its front end in place and also the end face 60. In addition, a lower clam shell housing 70 is shown positioned around the guide body 40 and capturing a front edge 41 thereof. It'also encloses its rear face 48 and has a half tubular extension 71 that is arranged to enclose the cone sleeve 33, as well as a part of the sheath 14 of the microduct assembly. In Figure 3d, a corresponding top clam shell 72 is shown fitted and this may be welded to the lower half 70 by ultrasonic welding, and optionally also to the body 40 and connector sleeve 33. However, it may be preferable to permit the connector plug 100 to be dismantled in the field. In this event, the clamshells are detachably connected together, for example by appropriate screw fixings.

Rings 74 are formed on the end of the extension 71, and these are adapted to be engaged by an end ring cap 76 (see Figure 3e) which incorporates catches to lock onto the rings 44, but also contains an 0'ring seal (not visible) that provides a seal between the sheath 14 and the clam shell housing 70,72.