GB1583383A - Optical cables - Google Patents

Optical cables Download PDF

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Publication number
GB1583383A
GB1583383A GB2023377A GB2023377A GB1583383A GB 1583383 A GB1583383 A GB 1583383A GB 2023377 A GB2023377 A GB 2023377A GB 2023377 A GB2023377 A GB 2023377A GB 1583383 A GB1583383 A GB 1583383A
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United Kingdom
Prior art keywords
tube
elongate
tape
optical
longitudinally extending
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GB2023377A
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Balfour Beatty PLC
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BICC PLC
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Priority to GB2023377A priority Critical patent/GB1583383A/en
Publication of GB1583383A publication Critical patent/GB1583383A/en
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    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/44Mechanical structures for providing tensile strength and external protection for fibres, e.g. optical transmission cables
    • G02B6/4479Manufacturing methods of optical cables
    • G02B6/448Ribbon cables
    • GPHYSICS
    • G02OPTICS
    • G02BOPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/44Mechanical structures for providing tensile strength and external protection for fibres, e.g. optical transmission cables
    • G02B6/4401Optical cables
    • G02B6/4403Optical cables with ribbon structure

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Light Guides In General And Applications Therefor (AREA)

Description

(54) IMPROVEMENTS IN OR RELATING TO OPTICAL CABLES (71) We, BICC Limited, a British Company, of 21 Bloomsbury Street, London WC1B 3QN, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to optical cables for the transmission of the ultraviolet, visible and infra-red regions of the electromagnetic spectrum, which regions, for convenience, will hereinafter all be included in the generic term " light ", and especially, but not exclusively, to optical cables for use in the communication field adapted for transmission of light having a wavelength within the range 0.8 to 1.3 micrometres.
According to the invention we provide an improved optical cable comprising at least one tube of metal or metal alloy having a transverse cross-section of elongate form, at least one major side wall of the tube being so shaped that longitudinally extending, transversely spaced parts of the wall are in contact with or adjacent to longitudinally extending, transversely spaced parts of the opposite major side wall of the tube to form longitudinally extending elongate compartments; at least one separate optical fibre and/or at least one optical bundle housed loosely in at least one of the elongate compartments; and, surrounding and bonded to the tube, an extruded body of rubber or plastics material.
By the expression "optical bundle" is meant a group of optical fibres or a group of fibres including one or more optical fibres and one or more non-optical reinforcing fibres or other reinforcing elongate elements.
Each optical fibre and/or non-optical fibre may be of circular or non-circular crosssection.
By virtue of being loosely housed in an elongate compartment extending lengthwise in the tube, limited relative movement between the or each separate optical fibre and/or between the or each optical bundle and the tube can take place when the cable is flexed.
The or each separate optical fibre and/or optical bundle may be of a length substantially greater than that of the tube but preferably the or each separate optical fibre and/or optical bundle and the tube are of equal or approximately equal lengths.
Viewed in transverse cross-section, the said shaped major side wall of the tube may be corrugated with the longitudinally extending crests of the corrugations in contact with or adjacent to longitudinally extending, transversely spaced parts of the opposite major side wall. In an alternative embodiment, each of the opposed major side walls of the tube, viewed in transverse cross-section, may be corrugated, with the longitudinally extending crests of the corrugations in the side walls in contact with or adjacent to one another and with the troughs of the corrugations in the side walls combining to define the longitudinally extending elongate compartments. Preferably, the axes of the elongate compartments and the longitudinal axis of the cable lie in a substantially common plane. Where, as is preferred, the extruded body of rubber or plastics material has a transverse crosssection of elongate form, the axes of the elongate compartments and the longitudinal and major transverse axes of the cable will lie in a substantially common plane.
Preferably, the tube is a tape or tapes of metal or metal alloy folded transversely of its or their length or otherwise arranged to form a tube having a transverse cross-section of elongate form, the outwardly facing major surface of the or each tape carrying a layer of rubber or plastics material to which the surrounding extruded body is bonded.
Where longitudinally extending parts of the internal surfaces of the major side walls of the tube are in contact, at least those parts of the internal surfaces may also carry layers of rubber or plastics material so that the parts of the opposed major side walls that are in contact are bonded together.
The or each tape, which may or may not have a layer of rubber or plastics material on its outwardly facing major surface, may have bonded to its outer surface elongate elements of reinforcing material, e.g. glass fibres, which extend lengthwise with respect to the tape and which have a coefficient of linear expansion that is preferably sub stantially the same as that of the tape.
With a view to preventing -mechanical damage to the surface of any optical fibre arising from abrasion with another optical fibre and/or the wall of the tube when flexing of the optical cable occurs, the interstices between the or each separate optical fibre and/or optical bundle in a compartment and the wall of the tube may be filled throughout the length of the cable with a greasy filling medium which will permit relative sliding movement between fibres and/or bundles and the tube when the cable is flexed. If the filling medium is a water-impermeable medium customarily employed in fully-filled telecommunication cables, it will also serve as a -longitudinally continuous barrier to the ingress of moisture along the interstices in the compartment. Preferably the filling medium employed consists of, or comprises as a major constituent, petroleum jelly.
At least one of the elongate compartments may house loosely one or more than one elongate electric conductor which, depending on the material of the internal surface of the tube and on whether or not another electric conductor is housed in the same compartment, may or may not be insulated.
At least one separate elongate reinforcing member may be embedded in the extruded body alongside but spaced from the tube with the axis of the reinforcing member lying in or close to the plane containing the major transverse dimension of the tube.
Preferably the or each elongate reinforcing member is substantially parallel to the tube, the axes of the elongate compartments in the tube and of the reinforcing member or members lying in a substantially common plane. Where the optical cable includes two or more elongate reinforcing members, the tube may be located between two reinforcing members. The tube may lie wholly in the space bounded by two planes located on opposite sides of two reinforcing members and touching both members so that the optical fibre or fibres is or are protected by the reinforcing members against crushing. The transverse crosssection of the extruded elongate body may be such that, over that part of the cable extending between planes substantially perpendicular to said common plane and passing through the axes of the reinforcing members, the thickness of the body is substantially less than the thickness of the body measured in said perpendicular planes.
The or each reinforcing member is of such a material and of such a crosssectional area having regard to the material or materials and cross-sectional area of the separate optical fibre or fibres and/or of the optical bundle or bundles that the strain otherwise imparted to the or each optical fibre when the cable is stressed in such a way as to tend to subject the or any optical fibre to a tensile force is eliminated or reduced at least to a substantial extent by the reinforcing member or members.
The or each elongate reinforcing member may be a single solid element or, with a view to making the optical cable as flexible as possible, the or each reinforcing member may comprise a plurality of elements stranded together. The or each element is preferably of steel, carbon fibre or any other suitable material having the necessary Young's Modulus.
Where the or each reinforcing member is of stranded form, for instance a strand of steel wires, the strand is preferably dieformed; that is to say, a strand that has been passed through a die which effects a reduction in the overall diameter of the strand. Such a compacted strand has the advantage over non-compacted strands of a higher apparent Young's Modulus at low strain.
A reinforcing wall comprising at least one layer comprising one or more than one element of reinforcing material may be wholly or partially embedded in or may surround the extruded body surrounding and bonded to the tube of metal or metal alloy.
The elongate element or elongate elements of reinforcing material may be wound helically about the extruded body or they may extend lengthwise of, and preferably substantially parallel to, the axes of the elongate compartments of the tube.
Where the reinforcing elongate element or elongate elements of the reinforcing wall are wound helically about the extruded body, preferably the reinforcing wall comprises at least two layers of elongate elements of reinforcing material wound helically about the extruded body, the directions of lay of adjacent layers being of opposite hand. The helically wound elongate elements of adjacent layers may be interwoven to form a braided sleeve of reinforcing material and in this case the braided sleeve may be partially or wholly embedded in the extruded body.
Alternative to or additional to the reinforcing wall, the extruded body sur rounding and bonded to the tube of metal or metal alloy may be surrounded by an oversheath of extruded rubber or plastics material, preferably a material having a low friction coefficient, such as nylon.
Where an oversheath is provided, the reinforcing wall may be embedded in the oversheath. Preferably, some or all of the elongate elements of reinforcing material are embedded at spaced positions around the extruded body or the oversheath and extend substantially lengthwise of the cable and each has, in the element, undulations, preferably radially extending undulations, that serve to improve the mechanical bonding of the element within the body or the oversheath and the flexibility of the cable.
The elongate elements of reinforcing material having undulations therein may each comprise a single wire or a plurality of wires stranded together, the wire or strand being crimped at spaced positions along its length to form undulations but, with a view to maintaining the weight of the cable as low as possible, preferably each of these elongate reinforcing elements comprises a bunch of compacted yarns of glass fibre or other inorganic reinforcing material.
Where the undulating elongate reinforcing elements are bunches of compacted yams of glass fibre or of other inorganic reinforcing material, preferably these yarns are not pre-impregnated with an agent for binding to the material of the oversheath and, preferably, also, there is substantially no air in the interstices between the elementary filaments of the bunch. Each bunch may consist of elements of glass fibre or of other inorganic material of the same kind and/or thickness or it may consist of a combination of elements of different kinds from one another, for example single or doubled yarns, and! our of different thicknesses from one another.
The invention also includes a method of making an optical cable as hereinbefore described, which method comprises causing at least one tape of metal or metal alloy, which has a layer of rubber or plastics materials on at least one of its major surfaces and which is so shaped that, viewed transversely of its length, the tape is corrugated, to travel in the direction of its length; folding the tape or tapes transversely or otherwise arranging the tapes in such a way that the layer of rubber or plastics material of the or each tape is outermost and adjacent longitudinally extending edges of the tape or tapes overlap to form a tube of elongate transverse cross-section and that longitudinally extending, transversely spaced parts of the inwardly facing surface or surfaces of the tape or tapes are in contact with or are adjacent to one another and define at least two longitudinally extending elongate compartments; feeding into at least one of the elongate compartments as they are being formed at least one separate optical fibre and / or at least one optical bundle, the relative cross-sectional sizes of the compartment and the optical fibre or fibres and/or the optical bundle or bundles being such that the fibre or fibres and/or the optical bundle or bundles is or are loosely housed in the compartment; and extruding around the tube so formed an elongate body of rubber or plastics material which bonds to the layer of rubber or plastics material overlying the tube.
Preferably, the tube of elongate transverse cross-section may be formed by causing a corrugated tape of metal or metal alloy and a substantially flat tape of metal or metal alloy, each having a layer of rubber or plastics material on at least one of its surfaces, to advance in the direction of their lengths and arranging one on top of the other so that the crest of the corrugated tape are in contact with or adjacent to longitudinally extending, transversely spaced parts of the other tape, at least one of the tapes being so formed that their adjacent longitudinal edges overlap and, when the elongate body is extruded around the tube so formed, are bonded together.
Alternatively, the tube of elongate transverse cross-section may be formed by transversely folding a single advancing corrugated tape of metal or metal alloy, which tape has a layer of rubber or plastics material on at least its outwardly facing surface, so that its longitudinal edges overlap and, when the elongate body is extruded therearound, are bonded together and that the crests on one major side wall of the tube are in contact with or are adjacent to the crests on the other major side wall to bound longitudinally extending elongate compartments defined by the troughs on the two major side walls.
To facilitate feeding of the or each separate optical fibre and/or optical bundle into an elongate compartment in the tube, preferably the leading end of the fibre and/ or bundle is lightly bonded to the inside surface of the tube by a suitable adhesive.
The optical cable of the present invention has two major advantages. Firstly, the tube of metal or metal alloy housing loosely the separate optical fibre or fibres and/or the optical bundle or bundles constitutes a circumferentially continuous moisture-proof barrier. Secondly, since the or each separate optical fibre and/or optical bundle can be housed loosely in an elongate compartment, ready identification of an optical fibre or optical bundle at any transverse cross-section of the cable is facilitated. Furthermore where the interstices within each compartment are filled throughout the length of the cable with petroleum jelly or other water-impermeable medium, the interior of each compartment has a longitudinally extending barrier to any water that may enter the cable at a damaged position along the extruded elongate body and underlying metal tube.
The invention is further illustrated by a description, by way of example, of a pr- ferred optical cable with reference to the accompanying drawing, in which: Figure 1 is a transverse cross-sectional view of the optical cable, drawn on an enlarged scale, and Figure 2 is a schematic representation of the method and apparatus employed in making the optical cable shown in Figure 1.
Referring to the drawing, the optical cable shown in Figure 1 comprises an aluminium tube 1 having a transverse cross-section of elongate form, the tube consisting of a flat aluminium tape 2 which has on its outer surface a layer 3 of polyethylene and an aluminium tape 4 which has on its outer surface a layer 5 of polyethylene and which, viewed in transverse cross-section, is corrugated. The longitudinally extending crests 6 of the corrugated tape 4 are in contact with longitudinally extending, transversely spaced parts of the tape 2 to form elongate compartments 7 in each of which an optical fibre 8 is loosely housed.
-The tube 1 is embedded in an extruded body 9 of polyethylene which is bonded to the polyethylene layers 3 and 5. Also - embedded in the extruded body 9 on opposite sides of the tube 1 are two steel reinforcing wires 10, the axes of the elongate compartment 7 and the reinforcing wires 10 and the longitudinal and major transverse axes of the body 9 lying in a substantially common plane. In order that the optical fibres 8 are protected against crushing, the tube 1 lies wholly in the space bounded by two planes located on opposite sides of the reinforcing wires 10 and touching both wires.
The body 9 has a major transverse dimension of 18mm and a minor transverse dimension of 4mm; each wire 10 has a diameter of 10mum; the tube 1 has a major transverse dimension of 10mum; each elongate compartment has major and minor transverse dimensions each of approximately 1.0m; and each optical fibre has a diameter of 125um.
As will be seen on referring to Figure 2, in manufacturing the optical cable shown in Figure 1, aluminium tape 4 having a coating 5 of polethylene on one of its surfaces is fed from a supply l l through a corrugating device 12 where the advancing tape is so shaped that, viewed in transverse cross-section, the tape is corrugated.
On emerging from the corrugating device 12, the corrugated tape 4 passes over a guide roller 14 where optical fibres 8 are fed into the longitudinally extending troughs of the corrugated tape. As the corrugated tape 4 and optical fibres 8 advance towards a guide roller 15, aluminium tape 2 having a coating 3 of polyethylene on one of its surfaces is fed from a supply 16 to the guide roller 15 where it is arranged on top of the corrugated tape 4 so that the polyethylene coatings 3 and 5 are outermost.
From the guide roller 15, the overlying tapes 2, 4 travel through nip rolls 17 where longitudinally extending, transversely spaced parts of the tape 2 are urged into contact with the crests 6 of the corrugated tape to form elongate compartments 7.
The overlying tapes 2, 4 and steel wires 10 (not shown) advancing on each side of the tapes then pass to an extruder 18 where polyethlene is extruded around the overlying tapes and the steel wires 10 to form an extruded body 9.
WIlAT WE CLAIM IS: 1. An optical cable comprising at least onc tube of metal or metal alloy having a transverse cross-section of elongate form, at least one major side wall of the tube being so shaped that longitudinally extending, transversely spaced parts of the wall are in contact with or adjacent to longitudinally extending, transversely spaced parts of the opposite major side wall of the tube to form longitudinally extending elongate compartments; at least one separate optical fibre and/or at least one optical bundle housed loosely in at least one of the elongate compartments; and, surrounding and bonded to the tube, an extruded body of rubber or plastics material.
2. An optical cable comprising at least one tube of metal or metal alloy having a transverse cross-section of elongate form, one major side wall of the tube being so shaped that, viewed in transverse crosssection, the wall is corrugated with the longitudinally extending crests of the corrugations in contact with or adjacent to longitudinally extending, transversely spaced parts of the opposite major side wall of the tube to form longitudinally extending elongate compartments; at least one separate optical fibre and / or at least one optical bundle housed loosely in at least one of the elongate compartments; and, surrounding and bonded to the tube, an extruded body of rubber or plastics material.
3. An optical cable comprising at least one tube of metal or metal alloy having a transverse cross-section of elongate form, each of the opposed major side walls of the tube being so shaped that, viewed in trans
**WARNING** end of DESC field may overlap start of CLMS **.

Claims (24)

**WARNING** start of CLMS field may overlap end of DESC **. facilitated. Furthermore where the interstices within each compartment are filled throughout the length of the cable with petroleum jelly or other water-impermeable medium, the interior of each compartment has a longitudinally extending barrier to any water that may enter the cable at a damaged position along the extruded elongate body and underlying metal tube. The invention is further illustrated by a description, by way of example, of a pr- ferred optical cable with reference to the accompanying drawing, in which: Figure 1 is a transverse cross-sectional view of the optical cable, drawn on an enlarged scale, and Figure 2 is a schematic representation of the method and apparatus employed in making the optical cable shown in Figure 1. Referring to the drawing, the optical cable shown in Figure 1 comprises an aluminium tube 1 having a transverse cross-section of elongate form, the tube consisting of a flat aluminium tape 2 which has on its outer surface a layer 3 of polyethylene and an aluminium tape 4 which has on its outer surface a layer 5 of polyethylene and which, viewed in transverse cross-section, is corrugated. The longitudinally extending crests 6 of the corrugated tape 4 are in contact with longitudinally extending, transversely spaced parts of the tape 2 to form elongate compartments 7 in each of which an optical fibre 8 is loosely housed. -The tube 1 is embedded in an extruded body 9 of polyethylene which is bonded to the polyethylene layers 3 and 5. Also - embedded in the extruded body 9 on opposite sides of the tube 1 are two steel reinforcing wires 10, the axes of the elongate compartment 7 and the reinforcing wires 10 and the longitudinal and major transverse axes of the body 9 lying in a substantially common plane. In order that the optical fibres 8 are protected against crushing, the tube 1 lies wholly in the space bounded by two planes located on opposite sides of the reinforcing wires 10 and touching both wires. The body 9 has a major transverse dimension of 18mm and a minor transverse dimension of 4mm; each wire 10 has a diameter of 10mum; the tube 1 has a major transverse dimension of 10mum; each elongate compartment has major and minor transverse dimensions each of approximately 1.0m; and each optical fibre has a diameter of 125um. As will be seen on referring to Figure 2, in manufacturing the optical cable shown in Figure 1, aluminium tape 4 having a coating 5 of polethylene on one of its surfaces is fed from a supply l l through a corrugating device 12 where the advancing tape is so shaped that, viewed in transverse cross-section, the tape is corrugated. On emerging from the corrugating device 12, the corrugated tape 4 passes over a guide roller 14 where optical fibres 8 are fed into the longitudinally extending troughs of the corrugated tape. As the corrugated tape 4 and optical fibres 8 advance towards a guide roller 15, aluminium tape 2 having a coating 3 of polyethylene on one of its surfaces is fed from a supply 16 to the guide roller 15 where it is arranged on top of the corrugated tape 4 so that the polyethylene coatings 3 and 5 are outermost. From the guide roller 15, the overlying tapes 2, 4 travel through nip rolls 17 where longitudinally extending, transversely spaced parts of the tape 2 are urged into contact with the crests 6 of the corrugated tape to form elongate compartments 7. The overlying tapes 2, 4 and steel wires 10 (not shown) advancing on each side of the tapes then pass to an extruder 18 where polyethlene is extruded around the overlying tapes and the steel wires 10 to form an extruded body 9. WIlAT WE CLAIM IS:
1. An optical cable comprising at least onc tube of metal or metal alloy having a transverse cross-section of elongate form, at least one major side wall of the tube being so shaped that longitudinally extending, transversely spaced parts of the wall are in contact with or adjacent to longitudinally extending, transversely spaced parts of the opposite major side wall of the tube to form longitudinally extending elongate compartments; at least one separate optical fibre and/or at least one optical bundle housed loosely in at least one of the elongate compartments; and, surrounding and bonded to the tube, an extruded body of rubber or plastics material.
2. An optical cable comprising at least one tube of metal or metal alloy having a transverse cross-section of elongate form, one major side wall of the tube being so shaped that, viewed in transverse crosssection, the wall is corrugated with the longitudinally extending crests of the corrugations in contact with or adjacent to longitudinally extending, transversely spaced parts of the opposite major side wall of the tube to form longitudinally extending elongate compartments; at least one separate optical fibre and / or at least one optical bundle housed loosely in at least one of the elongate compartments; and, surrounding and bonded to the tube, an extruded body of rubber or plastics material.
3. An optical cable comprising at least one tube of metal or metal alloy having a transverse cross-section of elongate form, each of the opposed major side walls of the tube being so shaped that, viewed in trans
verse cross-section, each major side wall is corrugated with the longitudinally extending crests of the corrugations in the side walls in contact with or adjacent to one another and with the troughs of the corrugations in the side walls combining to define longitudinally extending elongate compartments; at least one separate optical fibre and/or at least one optical bundle housed loosely in at least one of the elongate compartments; and, surrounding and bonded to the tube, an extruded body of rubber or plastics material.
4. An optical cable as claimed in any one of the preceding Claims, wherein the axes of the elongate compartments and the longitudinal axis of the cable lie in a substantially common plane.
5. An optical cable as claimed in any one of Claims 1 to 3, wherein the extruded body of rubber or plastics material has a transverse cross-section of elongate form and the. axes of elongate compartments and the longitudinal and major transverse axes of the cable lie in a substantially common plane.
6. An optical cable as claimed in any one of the preceding Claims, wherein the tube is a tape or tapes of metal or metal alloy folded transversely of its or their length or otherwise arranged to form a tube having a transverse cross-section of elongate form, the outwardly facing major surface of the or each tape carrying a layer of rubber or plastics material to which the surrounding extruded body is bonded.
7. An optical cable as claimed in Claim 6, wherein at least those parts of the internal surfaces of the major side walls of the tube which are in contact carry layers of rubber or plastics materials so that the parts of the opposed major side walls that are in contact are bonded together.
8. An optical cable as claimed in Claim 6 or 7, wherein the or each tape has bonded to its outer surface elongate elements of reinforcing material which extend lengthwise with respect to the tape.
9. An optical cable as claimed in any one of the preceding Claims, wherein the or each separate optical fibre and/or optical bundle and the tube are of equal or approximately equal lengths.
10. An optical cable as claimed in any one of the preceding Claims, wherein in the or each compartment loosely housing at least one separate optical fibre and/or optical bundle, the interstices between the or each optical fibre and/or bundle and the wall of the tube are filled throughout the length of the cable with a greasy filling medium.
11. An optical cable as claimed in any one of the preceding Claims, wherein at least one of the elongate compartments loosely houses one or more than one elongate electric conductor.
12. An optical cable as claimed in any one of the preceding Claims, wherein at least one separate elongate reinforcing member is embedded in the extruded elongate body alongside but spaced from the tube with the axis of the reinforcing member lying in or close to the plane containing the major transverse dimension of the tube.
13. An optical cable as claimed in Claim 12, wherein the tube is located between at least two reinforcing members which extend- substantially parallel to the tube, the axes of the elongate compartments in the tube and of the reinforcing members lying in a substantially common plane.
14. An optical cable as claimed in Claim 13, wherein the tube lies wholly in the space bounded by two planes located on opposite sides of two reinforcing members and touching both members.
15. An optical cable as claimed in Claim 13, wherein the transverse cross-section of the extruded elongate body is such that, over that part of the cable extending between planes substantially perpendicular to said common plane and passing through the axes of reinforcing members on opposite sides of the tube, the thickness of the body is substantially less than the thickness of the body measured in said perpendicular planes.
16. An optical cable as claimed in any one of the preceding Claims, wherein the extruded body is surrounded by an oversheath of extruded rubber or plastics material having a low friction coefficient.
17. An optical cable as claimed in any one of the preceding Claims, wherein a reinforcing wall comprising at least one layer comprising one or more than one element of reinforcing material surrounds the extruded body or is wholly or partially embedded in the extruded body or, when present, the oversheath.
18. An optical cable as claimed in Claim 17 in which elongate elements of reinforcing material are embedded at spaced positions around the extruded body or the oversheath and extend substantially lengthwise of the cable, wherein some or all of the elongate elements each has, in the element, undulations that serve to improve the mechanical bonding of the element within the body or oversheath and the flexibility of the cable.
19. A method of making an optical cable which comprises causing at least one tape of metal or metal alloy, which has a layer of rubber or plastics material on at least one of its major surfaces and which is so shaped that, viewed transversely of its length, the tape is corrugated, to travel in the direction of its length; folding the tape or tapes transversely or otherwise arranging the tapes in such a way that the layer of rubber or plastics material of the or each tape is outermost and adjacent longitudinally extending edges of the tape or tapes overlap to form a tube of elongate transverse cross-section and that longitudinally extending, transversely spaced parts of the inwardly facing surface or surfaces of the tape or tapes are in contact with or are adjacent to one another and define at least two longitudinally extending elongate compartments; feeding into at least one of the elongate compartments as they are being formed at least one separate optical fibre and/or at least one optical bundle, the relative cross-sectional sizes of the compartment and the optical fibre or fibres and/or the optical bundle or bundles being such that the fibre or fibres and/or the optical bundle or bundles is or are loosely housed in the compartment; and extruding around the tube so formed an elongate body of rubber or plastics material which bonds to the layer of rubber or plastics material overlying the tube.
20. A method as claimed in Claim 19, wherein the tube of elongate transverse cross-section is formed by transversely folding a single advancing corrugated tape of metal or metal alloy so that its longitudinal edges overlap and, when the elongate body is extruded therearound, are bonded together and that the crests on the major side wall of the tube are in contact with or are adjacent to the crests on the other major side wall to bound longitudinally extending elongate compartments defined by the troughs on the two major side walls.
21. A method of making an optical cable which comprises causing a tape of metal or metal alloy, which viewed transversely of its length is corrugated, and a substantially flat tape of metal or metal alloy, each having a layer of rubber or plastics material on at least one of its surfaces, to advance in the direction of their lengths; arranging the tapes one on top of the other so that the layer of rubber or plastics material of each tape is outermost and adjacent longitudinally extending edges of the tapes overlap to form a tube of elongate transverse cross-section and that the crests of the corrugated tape are in contact with or adjacent to longitudinally extending, transversely spaced parts of the other tape to define longitudinally extending elongate compartments; feeding into at least one of the elongate compartments as they are being formed at least one separate optical fibre and/or at least one optical bundle, the relative cross-sectional sizes of the compartment and the optical fibre or fibres and/or the optical bundle or bundles being such that the fibre or fibres and/or the optical bundle or bundles is or are loosely housed in the compartment; and extruding around the tube so formed an elongate body of rubber or plastics material which bonds to the layer of rubber or plastics material overlying the tube.
22. A method as claimed in any one of Claims 19 to 21, wherein the leading end of the or each separate optical fibre and! our optical bundle is lightly bonded to the inside surface of the tube by adhesive.
23. An optical cable substantially as hereinbefore described with reference to and as shown in Figure 1 of the accompanying drawing.
24. A method of making an optical cable substantially as hereinbefore described with reference to Figure 2 of the accompanying drawing.
GB2023377A 1978-05-12 1978-05-12 Optical cables Expired GB1583383A (en)

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Cited By (9)

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EP0031175A1 (en) * 1979-12-12 1981-07-01 Koninklijke Philips Electronics N.V. Low-pressure mercury vapour discharge lamp
GB2141558A (en) * 1983-06-17 1984-12-19 Bicc Plc An improved optical fibre ribbon structure
GB2164471A (en) * 1984-09-14 1986-03-19 Telephone Cables Ltd Optical fibre cables
US4652323A (en) * 1984-01-09 1987-03-24 Olin Corporation Plasma deposition applications for communication cables
EP0282960A2 (en) * 1987-03-20 1988-09-21 Kabelmetal Electro GmbH Optical cable element and optical cable
US4798443A (en) * 1981-06-17 1989-01-17 Bicc Public Limited Company Optical cable
US4836639A (en) * 1986-03-04 1989-06-06 Fujikura Ltd. Optical fiber cable having a neutral axis defining a zero stress
GB2215080B (en) * 1988-02-11 1992-06-03 Stc Plc Optical fibre cables.
CN109991708A (en) * 2019-03-27 2019-07-09 江苏通光信息有限公司 Novel easily branched 8 shaped optical cable of one kind, molding die and its production technology

Cited By (11)

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