CA1118252A - Optical communication cable - Google Patents
Optical communication cableInfo
- Publication number
- CA1118252A CA1118252A CA000291828A CA291828A CA1118252A CA 1118252 A CA1118252 A CA 1118252A CA 000291828 A CA000291828 A CA 000291828A CA 291828 A CA291828 A CA 291828A CA 1118252 A CA1118252 A CA 1118252A
- Authority
- CA
- Canada
- Prior art keywords
- bore
- length
- cable
- throughout
- optical
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Landscapes
- Installation Of Indoor Wiring (AREA)
Abstract
A B S T R A C T
In an optical communication cable for the transmission of light, two or more optical fibres are secured side by side on or within a flat flexible support member which is so housed that it is capable of limited movement relative to the cable when the cable is flexed, thereby reducing risk of fracture of any optical fibre. The flexible support member is loosely housed in, and has dimensions less than the diameter of, a bore in an extruded elongate body of insulating material, which bore has a smooth continuous boundary wall and is of uniform transverse cross-section throughout its length. To provide reinforcement for the cable, two separate elongate reinforcing members are embedded in the extruded body throughout its length and are arranged on opposite sides of and parallel to the bore.
As compared with optical communication cables hitherto proposed, the optical cable is simple and inexpensive and because limited movement of the flexible support member -and hence of each optical fibre - can take place within the cable, there is substantially less risk of fracture of or damage to any optical fibre during manufacture and installation of the cable.
In an optical communication cable for the transmission of light, two or more optical fibres are secured side by side on or within a flat flexible support member which is so housed that it is capable of limited movement relative to the cable when the cable is flexed, thereby reducing risk of fracture of any optical fibre. The flexible support member is loosely housed in, and has dimensions less than the diameter of, a bore in an extruded elongate body of insulating material, which bore has a smooth continuous boundary wall and is of uniform transverse cross-section throughout its length. To provide reinforcement for the cable, two separate elongate reinforcing members are embedded in the extruded body throughout its length and are arranged on opposite sides of and parallel to the bore.
As compared with optical communication cables hitherto proposed, the optical cable is simple and inexpensive and because limited movement of the flexible support member -and hence of each optical fibre - can take place within the cable, there is substantially less risk of fracture of or damage to any optical fibre during manufacture and installation of the cable.
Description
This invention relates to optical guides for the transmission of the ultra-violet, 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 waveguides for use in the communications field adæpted for transmission of light.
The present invention provides an optical comm-unication cable that is relatively inexpensive and simple to manufacture.
~118~S2 According to the present invention the optical communication cable comprises an extruded elongate body of insulating material having extending throughout its length at least one bore which is defined by a substantially smooth continuous boundary wall and which is of substantially uniform transverse cross-section throughout the length of the bore; at least two optical fibres secured side-by-side on or within at least one substantially flat flexible support member which is housed loosely in and throughout the length of the bore and which has dimensions substantially less than the diameter of the bore so that at any transverse cross-section of the cable through-out the whole of its length, limited relative movement between the flexible support member and the extruded elongate body can take place when the cable is flexed;and, embedded in the extruded elongate body throughout the whole of the length of the body and arranged on opposite sides of and substantially parallel to the bore, at least two separate elongate reinforcing members.
Instead of or ln addition to two optical fibres secured side-by-side on or within the flexible support member, an optical bundle or optical bundles may be secured side-by-side on or within the flexible support member.
By the expression "optical bundle' is meant a group of optical fibres or a gloup of fibres including one or more optical fibres and one or more r.on-optical reinforcing fibres or other reinforcing elongate e].ements. Each optical fibre and/or non-optical fibre may be of circular or non-circular cross-section.
Since the substantially flat flexible support member on or within which the fibres and/or optical bundles are secured is housed loosely in a bore extending lengthwise in the extruded elongate body, limited relative movement between the flexible support member and the extruded elongate body - and hence between each optical fibre and!or each optical bundle and the extruded elongate body - can take place when the cable is flexed.
~g ~r ~ 2 3Z~
By virtue of the i'act that the position of each optical fibre and/or of each optical bundle secured on or within the ~lexible support member with respect to the other optical fibre or fibres and/or other optical bundle or bundles is constant throughout the length of the cable, any optical fibre and/or optical bundle can be readily identified at any transverse cross-section of the cable. Furthermore, since each optical fibre and/or each optical bundle is secured on or within a flexible support member, feeding of the optical fibres and/or optical bundles into the bore or bores of the extruded elongate body during manufacture of the cable, and especially when initially introducing thé
optlcal fibres and/or optical bundles into the bore or bores, is facilitated.
Where the extruded elongate body has a transverse cross-sectional shape of such a form that the parts of the body on opposite sides of a plane passing through the axis or axes of the bore or bores are substantially identical, preferably initial identification of the optical fibres and/or optical bundles is further facilitated by providing a longitudinally extending datum mark on the surface of the extruded elongate body.
Preferably the substantially flat i'lexible support member is in the form of at least one tape, for instance of paper or plastics material, of glass or of metal or metal alloy. In some circumstances, it is preferred that the or each tape is of a material having a coefficient of thermal expansion approximating to that of the material or materials of the optical fibres. For example, where the optical fibres are of a silica-based material, the or each tape may be of steel.
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Where the flexible support member consists of a single tape, the optical ~ibres and/or optical bundles may be secured by adhesive to one surface of the tape; viewed in transverse cross-section the tape may be corrugated so that it has a plurality oi' troughs extending along its length, in each of some or all of which an optical fibre or optical bundle may be secured. Where the flexible support member consists of two tapes, one overlying the other, the optical fibres and/or optical bundles may be sandwiched between the two tapes and secured by adhesive to the adjacent surfaces of the tapes; one or each of these two tapes may be transversely corrugated as described above. An alternative flexible support member comprises a single tape of plastics material with the optical fibres and/or optical bundles wholly or partially embedded in it.
An optical cable according to the invention can be manufactured using conventional extrusion techniques well known in the manufacture of electric cables. The or each ilexible support member, with the optical fibres secured thereon or therein, and the separate elongate reiniorcing members are fed side-by-side into the upstream end of an extru~ion machine which, by means of an appropriate hollow core point and an outer die at the extrusion orifice, extrudes insulating material about the advancing flexible support member and reiniorcing members in such a way as to form an extruded body which has a bore extending through-out its length, the i'lexible support member being loosely housed in the bore and each reinforcing member being embedded in the extruded body.
The invention is further illustrated by a description, by way of example, of two preferred forms of optical cable with reference to the accompanying drawings, in which:-ill~ZS~
Figure 1 is a cross-sectional view of a ~irst form of optical cable drawn on an enlarged scale; and Figure 2 is a cross-sectional view of a second form of optical cable drawn on an enlarged scale.
The optical cable shown in Figure 1 comprises an extruded elongate body 4 of polyèthylene having two bores 2 and, embedded in the extruded body on opposite sides of the bores, two steel wires 3, the axes of the bores and of the steel wires being substantially parallel and lying in a substantially common plane. The transverse cross-section of the elongate body 4 is of substantially dumb-bell shape comprising arcuate end parts 5 united by re-entrant parts 6 Loosely housed in each ofthebores 2 is a corrugated tape 7 of plastics material in the troughs of which separate - optical i'ibres 1 are secured by adhesive. A longitudinally extending rib 8 on the external surface of the body 4 facilitates ready identification of any of the optical fibres 1.
The optical cable illustrated in Figure 2 comprises an extruded elongate body 14 of polyethylene having a central bore 12 and, embedded in the extruded body on opposite sides of the bore, two steel wires 13, the axes o~ the bore and of the steel wires being substantially parallel and lying in a substantially common plane. The transverse cross-section of the elongate body 14 is of substantially dumb-bell shape. Loosely housed in the bore 12 is a steel tape 17 on the surface of which four optical fibres 11 are secured by adhesive.
It will be appreciated that the transverse cross-sectional shape of each of the cables shown in Figures 1 and 2 is such that each cable can be secured to a supp~rt ~5.~
by means of one or more than one two-part clamp which engages its opposi-te major side iaces with negligible risk of crushing of the optical. fibres occurring.
i
The present invention provides an optical comm-unication cable that is relatively inexpensive and simple to manufacture.
~118~S2 According to the present invention the optical communication cable comprises an extruded elongate body of insulating material having extending throughout its length at least one bore which is defined by a substantially smooth continuous boundary wall and which is of substantially uniform transverse cross-section throughout the length of the bore; at least two optical fibres secured side-by-side on or within at least one substantially flat flexible support member which is housed loosely in and throughout the length of the bore and which has dimensions substantially less than the diameter of the bore so that at any transverse cross-section of the cable through-out the whole of its length, limited relative movement between the flexible support member and the extruded elongate body can take place when the cable is flexed;and, embedded in the extruded elongate body throughout the whole of the length of the body and arranged on opposite sides of and substantially parallel to the bore, at least two separate elongate reinforcing members.
Instead of or ln addition to two optical fibres secured side-by-side on or within the flexible support member, an optical bundle or optical bundles may be secured side-by-side on or within the flexible support member.
By the expression "optical bundle' is meant a group of optical fibres or a gloup of fibres including one or more optical fibres and one or more r.on-optical reinforcing fibres or other reinforcing elongate e].ements. Each optical fibre and/or non-optical fibre may be of circular or non-circular cross-section.
Since the substantially flat flexible support member on or within which the fibres and/or optical bundles are secured is housed loosely in a bore extending lengthwise in the extruded elongate body, limited relative movement between the flexible support member and the extruded elongate body - and hence between each optical fibre and!or each optical bundle and the extruded elongate body - can take place when the cable is flexed.
~g ~r ~ 2 3Z~
By virtue of the i'act that the position of each optical fibre and/or of each optical bundle secured on or within the ~lexible support member with respect to the other optical fibre or fibres and/or other optical bundle or bundles is constant throughout the length of the cable, any optical fibre and/or optical bundle can be readily identified at any transverse cross-section of the cable. Furthermore, since each optical fibre and/or each optical bundle is secured on or within a flexible support member, feeding of the optical fibres and/or optical bundles into the bore or bores of the extruded elongate body during manufacture of the cable, and especially when initially introducing thé
optlcal fibres and/or optical bundles into the bore or bores, is facilitated.
Where the extruded elongate body has a transverse cross-sectional shape of such a form that the parts of the body on opposite sides of a plane passing through the axis or axes of the bore or bores are substantially identical, preferably initial identification of the optical fibres and/or optical bundles is further facilitated by providing a longitudinally extending datum mark on the surface of the extruded elongate body.
Preferably the substantially flat i'lexible support member is in the form of at least one tape, for instance of paper or plastics material, of glass or of metal or metal alloy. In some circumstances, it is preferred that the or each tape is of a material having a coefficient of thermal expansion approximating to that of the material or materials of the optical fibres. For example, where the optical fibres are of a silica-based material, the or each tape may be of steel.
G
Where the flexible support member consists of a single tape, the optical ~ibres and/or optical bundles may be secured by adhesive to one surface of the tape; viewed in transverse cross-section the tape may be corrugated so that it has a plurality oi' troughs extending along its length, in each of some or all of which an optical fibre or optical bundle may be secured. Where the flexible support member consists of two tapes, one overlying the other, the optical fibres and/or optical bundles may be sandwiched between the two tapes and secured by adhesive to the adjacent surfaces of the tapes; one or each of these two tapes may be transversely corrugated as described above. An alternative flexible support member comprises a single tape of plastics material with the optical fibres and/or optical bundles wholly or partially embedded in it.
An optical cable according to the invention can be manufactured using conventional extrusion techniques well known in the manufacture of electric cables. The or each ilexible support member, with the optical fibres secured thereon or therein, and the separate elongate reiniorcing members are fed side-by-side into the upstream end of an extru~ion machine which, by means of an appropriate hollow core point and an outer die at the extrusion orifice, extrudes insulating material about the advancing flexible support member and reiniorcing members in such a way as to form an extruded body which has a bore extending through-out its length, the i'lexible support member being loosely housed in the bore and each reinforcing member being embedded in the extruded body.
The invention is further illustrated by a description, by way of example, of two preferred forms of optical cable with reference to the accompanying drawings, in which:-ill~ZS~
Figure 1 is a cross-sectional view of a ~irst form of optical cable drawn on an enlarged scale; and Figure 2 is a cross-sectional view of a second form of optical cable drawn on an enlarged scale.
The optical cable shown in Figure 1 comprises an extruded elongate body 4 of polyèthylene having two bores 2 and, embedded in the extruded body on opposite sides of the bores, two steel wires 3, the axes of the bores and of the steel wires being substantially parallel and lying in a substantially common plane. The transverse cross-section of the elongate body 4 is of substantially dumb-bell shape comprising arcuate end parts 5 united by re-entrant parts 6 Loosely housed in each ofthebores 2 is a corrugated tape 7 of plastics material in the troughs of which separate - optical i'ibres 1 are secured by adhesive. A longitudinally extending rib 8 on the external surface of the body 4 facilitates ready identification of any of the optical fibres 1.
The optical cable illustrated in Figure 2 comprises an extruded elongate body 14 of polyethylene having a central bore 12 and, embedded in the extruded body on opposite sides of the bore, two steel wires 13, the axes o~ the bore and of the steel wires being substantially parallel and lying in a substantially common plane. The transverse cross-section of the elongate body 14 is of substantially dumb-bell shape. Loosely housed in the bore 12 is a steel tape 17 on the surface of which four optical fibres 11 are secured by adhesive.
It will be appreciated that the transverse cross-sectional shape of each of the cables shown in Figures 1 and 2 is such that each cable can be secured to a supp~rt ~5.~
by means of one or more than one two-part clamp which engages its opposi-te major side iaces with negligible risk of crushing of the optical. fibres occurring.
i
Claims (12)
1. An optical communication cable for transmission of light, which cable comprises an extruded elongate body of insulating material having extending throughout its length at least one bore which is defined by a substantially smooth continuous boundary wall and which is of substantially uniform transverse cross-section throughout the length of the bore; at least two optical fibres secured side-by-side on or within at least one substantially flat flexible support member which is housed loosely in and throughout the length of the bore and which has dimensions substantially less than the diameter of the bore so that at any transverse cross-section of the cable throughout the whole of its length, limited relative movement between the flexible support member and the extruded elongate body can take place when the cable is flexed; and, embedded in the extruded elongate body throughout the whole of the length of the body and arranged on opposite sides of and substantially parallel to the bore, at least two separate elongate reinforcing members.
2. An optical communication cable for transmission of light, which cable comprises an extruded elongate body of insulating material having extending throughout its length at least one bore which is defined by a substantially smooth continuous boundary wall and which is of substantially uniform transverse cross-section throughout the length of the bore; at least two optical fibres secured by adhesive side-by-side to one surface of a flexible tape which is housed loosely in and throughout the length of the bore and which has dimensions substantially less than the diameter of the bore so that at any transverse cross-section of the cable throughout the whole of its length, limited relative movement between the flexible tape and the extruded elongate body can take place when the cable is flexed; and, embedded in the extruded elongate body throughout the whole of the length of the body and arranged on opposite sides of and substantially parallel to the bore, at least two separate elongate reinforcing members.
3. An optical communication cable as claimed in Claim 2, wherein, viewed in transverse cross-section, the tape is corrugated so that it has a plurality of troughs extending along its length, in each of at least some of which an optical fibre is secured.
4. An optical communication cable for transmission of light, which cable comprises an extruded elongate body of insulating material having extending throughout its length at least one bore which is defined by a substantially smooth continuous boundary wall and which is of substantially uniform transverse cross-section throughout the length of the bore; at least two optical fibres sandwiched between and secured by adhesive side-by-side to the adjacent surfaces of two flexible tapes which are housed loosely in and throughout the length of the bore and which have dimensions substantially less than the diameter of the bore so that at any transverse cross-section of the cable throughout the whole of its length, limited relative movement between the flexible tapes and the extruded elongate body can take place when the cable is flexed;
and, embedded in the extruded elongate body throughout the whole of the length of the body and arranged on opposite sides of and substantially parallel to the bore, at least two separate elongate reinforcing members.
and, embedded in the extruded elongate body throughout the whole of the length of the body and arranged on opposite sides of and substantially parallel to the bore, at least two separate elongate reinforcing members.
5. An optical communication cable as claimed in Claim 4, wherein at least one of the two tapes is transversely corrugated so that it has a plurality of troughs extending along its length, in each of at least some of which an optical fibre is secured.
6. An optical communication cable as claimed in Claim 1, wherein the flexible support member comprises two overlying flexible tapes which are bonded together, at least one of which tapes, viewed in transverse cross-section, being so corrugated that it has a plurality of troughs extending along its length in each of at least some of which an optical fibre is housed and wherein the optical fibres are secured within the flexible support member but are capable of limited movement within the troughs in which they lie.
7. An optical communication cable as claimed in Claim 2 or 4, wherein the or each tape is of a metal or metal alloy.
8. An optical communication cable as claimed in Claim 2 or 4, wherein the or each tape is of paper or plastics material.
9. An optical communication cable as claimed in Claim 2 or 4, wherein the or each tape is of a material having a coefficient of thermal expansion approximating to that of the material or materials of the optical fibres.
10. An optical communication cable for transmission of light, which cable comprises an extruded elongate body of insulating material having extending throughout its length at least one bore which is defined by a substantially smooth continuous boundary wall and which is of substantially uniform transverse cross-section throughout the length of the bore; at least two optical fibres wholly or partially embedded side-by-side in a flexible tape of plastics material housed loosely in and throughout the length of the bore and which has dimensions substantially less than the diameter of the bore so that at any transverse cross-section of the cable throughout the whole of its length, limited relative movement between the flexible tape and the extruded elongate body can take place when the cable is flexed; and, embedded in the extruded elongate body throughout the whole of the length of the body and arranged on opposite sides of and substantially parallel to the bore, at least two separate elongate reinforcing members.
11. An optical communication cable as claimed in Claim 2, 4 or 10, wherein the extruded elongate body has a transverse cross-sectional shape of such a form that the parts of the body on opposite sides of a plane passing through the axis of the bore are substantially identical and wherein the surface of the extruded elongate body has a longitudinally extending datum mark for facilitating initial identification of the optical fibres.
12. An optical communication cable as claimed in Claim 2, 4 or 10, wherein the cross-sectional shape of the bore is of an elongate form with the flexible tape or tapes so loosely housed in the bore that the axes of the optical fibres lie in a plane that is approximately parallel to the major transverse dimension of the bore.
Priority Applications (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000291828A CA1118252A (en) | 1977-11-28 | 1977-11-28 | Optical communication cable |
| CA000369253A CA1144793A (en) | 1977-11-28 | 1981-01-23 | Optical communication cable |
| CA374,900A CA1124561A (en) | 1977-11-28 | 1981-04-07 | Optical fibre cable |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000291828A CA1118252A (en) | 1977-11-28 | 1977-11-28 | Optical communication cable |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1118252A true CA1118252A (en) | 1982-02-16 |
Family
ID=4110147
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000291828A Expired CA1118252A (en) | 1977-11-28 | 1977-11-28 | Optical communication cable |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1118252A (en) |
-
1977
- 1977-11-28 CA CA000291828A patent/CA1118252A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |