FR2766956A1 - BASIC TELECOMMUNICATION CABLE AND COMPOUND CABLE FOR HIGH SPEED SIGNALS - Google Patents

Abstract

The basic telecommunication cable comprising several insulated wires (3), an internal sheath (6) of insulating material surrounding the insulated conductor wires, a conductive screen (8) in the form of a ribbon fixed to the internal sheath (6) by gluing or welding , and a second sheath (11) surrounding the screen (8).

Description

The present invention relates to a cable

  basic telecommunication and a telecommunication cable

  compound composed of several telecommunication cables

  elementary, for high frequency telephone and / or data processing signals, particularly intended for the transmission of digital data at high

  speed of the order of 100 to 500 Mbit / s.

  In a local network installed in a building, there are two kinds of cables: low capacity cables with four, eight or twelve pairs, called horizontal distribution cables or capillary cables, and high capacity cables with twenty four, thirty two ,

  sixty or one hundred and twenty eight pairs, called distribution cables

  vertical bution or bypass cable. The bypass cables are generally made from capillary cable elements, each capillary cable element in this case being considered as an elementary telecommunication cable. The bypass cables extend between a general distributor and floor distributors or between

floor distributors.

  Known, in particular from document EP-A-599 672, an elementary telecommunication cable comprising two

  quarter of insulated conductors surrounded by an envelope

  loppe comprising an internal sheath of insulating material placed directly in contact with the insulated conductive wires, a metal screen arranged around the sheath

  internal and a second sheath surrounding the metal screen.

  The screen serves as a shield to prevent the signals carried by the cable from being disturbed by external electromagnetic radiation, as well as to avoid a disturbance of the surrounding space by the electromagnetic radiation of the cable, in particular to suppress crosstalk between adjacent capillary cables. In practice, the metal screen is generally made up of a metal tape (generally aluminum) fixed to a polymer tape and arranged around the internal sheath either by helical winding, or in a long laying, the edges tape being arranged to overlap. Each interruption of the shielding provided by the screen, whether it is a poor covering of the edges of the screen or a fold of the latter, is a source of parasitic emissions all the more important as the

frequency is high.

  This problem affects not only the cable itself

  same but also all the equipment associated with the cable, in particular the connectors and the interface between a cable and a connector. In this regard, it is generally known to use a shielded connector enclosing the screen over its entire periphery. To perform this operation, it is necessary during the installation of a capillary telecommunication cable to cut the external sheath in order to be able to remove it and release the screen. Given the small thickness of the outer sheath, it is frequent that the screen is also notched when cutting the outer sheath. This notch constitutes a beginning of rupture of the screen which then risks tearing when the sheath section is removed or during

  a bend in the telecommunication cable so that the electromagnetic shielding of the cable is no longer ensured.

  According to the invention, a television cable is proposed.

  elementary communication comprising several insulated wires, an internal sheath of insulating material surrounding the insulated conductive wires, and a ribbon-shaped conductive screen in contact with the internal sheath, in which the screen

  is fixed to the internal sheath by gluing or welding.

  Thus, when handling the TV cable

  communication, the efforts on the screen are distributed not only on the screen but also on the internal sheath

  whose screen is made integral so that the

  quences of a screen breaking primer are minimized and generally make it possible to avoid tearing the screen. In addition, it was found that fixing the screen to the internal sheath made it possible to minimize the risk of screen creasing during the manufacture of the cable as well as during subsequent manipulations of the cable so that the risk of leaks electromagnetic is minimized. According to an advantageous version of the invention,

  the screen has an insulating layer and a conductive layer

  trice fixed to each other and the screen is fixed to the internal sheath by the insulating layer. Thus the conductive layer is present on the outside of the cable and allows a connection

easy.

  According to another advantageous aspect of the invention, the cable comprises a second sheath surrounding the screen and a protective tape disposed between the screen and the second sheath and having overlapping edges. Thus, one minimizes the risk of making break initiations in the screen when cutting the second sheath to access the screen. Preferably in this case the protective tape comprises a conductive layer and an insulating layer fixed to the conductive layer, and the conductive layer of the

  protective tape is in contact with the conductive layer

  screen. Thus while ensuring protection of

  the screen further reduces electromagnetic interference

  and consequently improves the electromagnetic compatibility of the transmission cable. In addition, it facilitates the removal of the cut end of the second sheath and of the protective tape by a metal sliding.

  against metal protective tape on the screen.

  Other features and advantages of the

  vention will appear on reading the description which

  follows different embodiments of the elementary telecommunication cable according to the invention and of a compound telecommunication cable obtained from several elementary telecommunication cables with reference to the attached figures among which: - Figure 1 is a view in enlarged cutaway perspective of an elementary telecommunication cable according to the invention, - Figure 2 is an enlarged cross-sectional view of a telecommunication cable comprising several elementary telecommunication cables, - Figure 3 is a view similar to that of Figure 1 of a second embodiment of the invention, - Figure 4 is a view similar to that of the

  Figure 1 of a third embodiment of the invention.

  Referring to Figure 1, the telecom cable

  illustrated elementary munication, generally designated in 1, comprises two twisted star quartets 2 each comprising four conducting wires 3 covered with an individual insulating layer 4, for example made of polyethylene or polypropylene. The two quarters 2 are contained in an envelope generally designated at 5 comprising an internal sheath 6. The internal sheath 6 is preferably a sheath made of thermoplastic material produced by extrusion around the juxtaposed quarter. The internal sheath 6 can also be produced in the form of a ribbon wound tightly in a helix or laid lengthwise, the longitudinal edges of which overlap and can be glued or welded in order to form an oval or elliptical tube. Inside the internal sheath there is preferably provided a tearing cord 7 making it possible to tear the internal sheath 6 during connection of the conductive wires, for example to self-stripping contacts of a distribution module. The internal sheath 6 is surrounded by a screen 8 comprising in the first embodiment an insulating layer 9 fixed to a conductive layer 10. The screen 8 is for example made by fixing by bonding a polyester or polyethylene tape and a aluminum or copper tape. The composite tape thus obtained is placed around the internal sheath 6, for example in a helical winding as illustrated in FIG. 1, preferably placing the insulating layer 9 in contact with the internal sheath 6. Unlike

  previous achievements the screen 8 is not fixed on itself-

  same edge on edge but is fixed to the internal sheath 6 by gluing or welding. The paste operation can be

  performed for example by arranging at the outlet of the extru-

  deuse producing the internal sheath 6, or at the inlet of a take-up machine, a device for applying a hot-melt adhesive which is deposited in a thin layer on the internal sheath then by carrying out a helical wrapping of a ribbon aluminum and polyester composite, the polyester layer having for example a thickness of about 20 to 50 μm, while the aluminum layer has a thickness

about 10 to 80 gm.

  In the case where the insulating layer of the composite tape is compatible with the material forming the internal sheath 6, the fixing of the screen 8 to the internal sheath 6 can also be carried out by welding the screen to the sheath, for example by applying the screen 8 while the material forming the internal sheath 6 is still hot or by softening the external surface of the internal sheath 6 immediately upstream of the screen application device. 30 'A second sheath 11 is generally produced around screen 8 to protect it from

  attacks during handling of the telecommunication cable

  elementary cation. The second sheath 11 is for example produced by extrusion. Prior to the production of the second sheath 11, a rope is preferably put in place

  tear 12 and a continuity thread 13.

  The elementary telecommunication cable thus obtained can be used either as a capillary cable, preferably with an external sheath 11, or be associated with other elementary telecommunication cables to form a bypass cable as illustrated by FIG. 2 on which the cables basic telecommunication 1 do not have an external sheath 11 and are arranged so that the screens 8 are in contact with each other. In the illustrated embodiment, the bypass cable comprises several elementary telecommunication cables 1 arranged if necessary around a central support member 14. If necessary, the cable also includes one or more stuffing rods 15, for example a polymer rod, intended to give structure

  homogeneous to the cable in order to avoid in particular a tangled

  very basic telecommunication cables. The

  stuffing rod 15 may also contain one or more

  fiber optics. The elementary telecommunication cables and the stuffing rod are surrounded by a main metallic screen 16 itself surrounded by an external sheath 17. In the example illustrated where the elementary telecommunication cables are in contact with the screens 8, it suffices to provide a single continuity wire 18

  in contact with the main screen 16.

  FIG. 3 illustrates a second embodiment

  tion of an elementary telecommunication cable 1 compre-

  as above, two quads 2 extending inside an envelope 5 comprising an internal sheath 6 covered with a screen 8. In this embodiment, the screen 8 consists of a single metal layer 10 wound in propeller on the inner sheath 6. A ribbon of

  protection 19 is this time arranged around the screen 10.

  In this embodiment, the protective tape 19 is a tape made of insulating synthetic polymer arranged lengthwise and having overlapping edges 20. The protective tape 19 therefore does not adhere to the screen 8, it can thus be easily removed when cutting the second sheath 11 to strip the screen 8 and make a connection of the elementary transmission cable.

  Figure 4 illustrates a third embodiment.

  sation in which the elementary transmission cable again comprises, as previously, two quads 2 extending in an envelope 5 comprising an internal sheath 6. As in the first embodiment, the screen 8 is a composite ribbon wound helically around

  of the internal sheath 6. In this third embodiment,

  tion, the screen 8 is covered by a composite protective tape 21 comprising a metal layer 22 in contact with the metal layer 10 of the screen 8 and an insulating layer 23. The protective tape 21 is this time wound in a helix according to a reverse pitch of the helical winding of the screen 8, the edges 24 being arranged to overlap. As before, the protective tape 21

  is covered with a second sheath 11 made of insulating material.

  Of course, the invention is not limited to the embodiments described and it is possible to add to them

  alternative embodiments without departing from the scope of the invention as defined by the claims. 25 In particular, the telecommunication cable

  elementary according to the invention can be achieved with

pairs to replace the fourths.

  Although the screen 8 and the protective tape 19, 21 have been illustrated according to only three different embodiments, the combinations of arrangement and structure of each of these elements of the elementary telecommunication cable can be varied, for example by arranging the screen 8 in length associated with a protective tape wound in a helix or itself arranged in a length, etc. so that the edges of the screen and the edges of the protective tape

  are offset from each other.

  In addition, the telecommunications cable

  elementary according to the invention can be achieved by pre-

  seeing means of identification allowing identification

  easy cation of the conductors within an elementary transmission cable or identification of an elementary transmission cable within a composite cable, for example by providing an internal sheath 6 of transparent material and insulating layers 4 of different colors or comprising threads of different color, and / or by making a marking on the second sheath 11 or on the screen 8 in the form of one or more colored threads or bands extruded, printed or marked cold or hot.

Claims (8)

  1. Basic telecommunication cable   with several insulated wires (3), an internal sheath (6) made of insulating material surrounding the insulated conductive wires, and a conductive screen (8) in the form of a ribbon in contact with the internal sheath, characterized in that the screen (8 ) East   fixed to the internal sheath by gluing or welding.   2. Elementary telecommunication cable according to claim 1, characterized in that the screen (8) comprises an insulating layer (9) and a conductive layer (10) fixed to one another and in that the screen is fixed   to the internal sheath (6) by the insulating layer.   3. basic telecommunication cable according to claim 1, characterized in that it comprises a second sheath (11) disposed around the screen and a protective tape (19, 21) disposed between the screen (8) and the   second sheath (11) and having overlapping edges (20, 24)   singing. 4. Elementary telecommunication cable according to claim 3, characterized in that the protective tape (21) comprises a conductive layer (22) and a   insulating layer (23) fixed to each other.   5. Elementary telecommunication cable according to claim 4, characterized in that the conductive layer (22) of the protective tape (21) is in contact   with the conductive layer (10) of the screen (8).   6. Basic telecommunication cable according to   one of claims 3 to 5, characterized in that the   edges of the screen (8) are offset from the edges of the protective tape (19, 21).   7. Telecommunication cable including several   several basic telecommunication cables (1) according to   one of claims 1 to 6, characterized in that it   comprises a main screen (16) having an internal metal face surrounding the elementary cables (1) and an external sheath (17) for protection and maintenance surrounding the screen main (16).   8. Telecommunication cable according to the claim   tion 7, characterized in that it comprises at least one stuffing element (15).