U.S. patent application number 09/567133 was filed with the patent office on 2002-01-31 for reinforced optical fiber cable of unitube structure.
Invention is credited to Elisson, Peter, Paborn, Jorgen.
Application Number | 20020012508 09/567133 |
Document ID | / |
Family ID | 9498462 |
Filed Date | 2002-01-31 |
United States Patent
Application |
20020012508 |
Kind Code |
A1 |
Elisson, Peter ; et
al. |
January 31, 2002 |
Reinforced optical fiber cable of unitube structure
Abstract
The reinforced optical fiber cable of unitube structure
comprises a protective tube for protecting optical fibers and
reinforcing elements, together with an outer sheath around said
protective tube. In the cable said protective tube is of corrugated
tubular structure. Application: Long distance transmission
cable.
Inventors: |
Elisson, Peter; (Hickory,
NC) ; Paborn, Jorgen; (Ambjornarp, SE) |
Correspondence
Address: |
Sughrue Mion Zinn MacPeak & Seas
2100 Pennsylvania Avenue NW
Suite 800
Washington
DC
20037-3202
US
|
Family ID: |
9498462 |
Appl. No.: |
09/567133 |
Filed: |
May 8, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09567133 |
May 8, 2000 |
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08987841 |
Dec 9, 1997 |
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6091871 |
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Current U.S.
Class: |
385/113 |
Current CPC
Class: |
G02B 6/4433 20130101;
G02B 6/4486 20130101; G02B 6/4432 20130101 |
Class at
Publication: |
385/113 |
International
Class: |
G02B 006/44 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 9, 1996 |
FR |
96 15085 |
Claims
1. A reinforced optical fiber cable of unitube structure comprising
a protective tube for protecting optical fibers and reinforcing
elements around said protective tube together with an outer sheath,
wherein said protective tube is of corrugated tubular
structure.
2. A cable according to claim 1, wherein said corrugated tubular
structure is constituted by a transversely corrugated strip that is
rolled longitudinally to form a tube.
3. A cable according to claim 2, wherein said tube is made of
metal.
4. A cable according to claim 1, wherein said corrugated tubular
structure is made of a plastics material and is extruded around
said optical fibers.
5. A cable according to claim 1, wherein said reinforcing elements
comprise cords having high traction strength, embedded in said
outer sheath parallel to the axis of said cable and diametrally
opposite in pairs and in the vicinity of a diametral plane of said
cable.
6. A cable according to claim 1, wherein said reinforcing elements
comprise a reinforcing layer between said corrugated tubular
structure and said outer sheath.
7. A cable according to claim 6, wherein said reinforcing layer
includes elements that are strong in traction wound helically
around said corrugated tubular structure.
8. A cable according to claim 6, wherein said reinforcing layer is
constituted by an annular layer of plastics material extruded
around said corrugated tubular structure.
9. A cable according to claim 8, wherein said reinforcing layer
includes reinforcing fibers in the extruded annular layer.
10. A cable according to claim 1, including a filler material in
said corrugated tubular structure.
11. A cable according to claim 10, wherein said filler material is
a material which swells in the presence of water.
Description
[0001] The present invention relates to a reinforced optical fiber
cable of unitube structure comprising a protective tube containing
the optical fibers, reinforcing elements around the protective
tube, and an outer sheath.
BACKGROUND OF THE INVENTION
[0002] Such a cable is intended in particular for long distance
data transmission.
[0003] Document EP-A-0 696 750 discloses a cable of that type, in
which the optical fibers, whether independent from one another or
assembled together in at least one ribbon, are contained inside a
protective tube of plastic together with a filler material for
filling the tube. The reinforcing elements of the tube are made of
a plastics material that is reinforced by reinforcing fiber and
known as FRP material, and they are cabled on the protective tube
by being assembled to one another. The outer sheath of the tube is
extruded over the reinforcing elements once they are in place.
[0004] To manufacture such a cable, the optical core defined by the
protective tube containing the optical fibers and the filler
material is often made initially on a first manufacturing line,
while the reinforcing elements are made and put into place around
the optical core, with the outer sheath being simultaneously
extruded thereabout, on a second line for cable manufacture proper.
The differences between the materials of the protective tube and of
the sheath in particular mean that stresses can be generated while
the extruded sheath is cooling, which stresses are then transmitted
to the protective tube and are liable to affect the fibers
contained in said protective tube. As a result, the cable is made
in two stages and manufacture is lengthy, thereby causing the cost
of the cable to be relatively high.
OBJECT AND SUMMARY OF THE INVENTION
[0005] An object of the present invention is to provide an optical
fiber cable of a structure that avoids those problems so as to
enable it to be made in a single stage.
[0006] The invention provides a reinforced optical fiber cable of
unitube structure comprising a protective tube for protecting
optical fibers and reinforcing elements around said protective tube
together with an outer sheath, wherein said protective tube is of
corrugated tubular structure.
[0007] Additionally and advantageously:
[0008] the corrugated tubular structure is constituted by a
transversely corrugated metal strip that is deformed longitudinally
into a tube, or is made of a plastics material and is extruded;
[0009] the reinforcing elements include a reinforcing layer between
said corrugated tubular structure and said outer sheath and/or
cords that are strong in traction embedded in the outer sheath
parallel to the axis of the cable, being disposed diametrally
opposite one another in pairs and close to a diametral plane of
said cable.
BRIEF DESCRIPTION OF THE DRAWING
[0010] The characteristics and advantages of the invention appear
from the following description of an embodiment given by way of
preferred example and illustrated in the sole FIGURE of the
accompanying drawing.
[0011] The sole FIGURE is a section view through a cable of the
invention. The cable comprises: optical fiber ribbons 1, or in a
variant mutually independent optical fibers; a corrugated tubular
structure 2 around the ribbons; and an outer sheath 3 extruded
around the tubular structure 2. Preferably, the inside space in
which the optical fiber ribbons are received contains a filler
material 4 serving in particular to protect the optical fibers
against penetration of moisture. The filler material is a material
which stops water and thus prevents it penetrating, or is a
material which swells in the presence of water.
MORE DETAILED DESCRIPTION
[0012] In the embodiment shown, the cable has cords or rods that
are relatively stiff and that have high traction strength, which
are embedded in the sheath, parallel to the axis of the cable. By
way of example, these cords may be made of reinforced plastics
material or of steel. There are two such cords in the embodiment
shown, in which they are opposite each other. In a variant, there
could be four of them, in which case they would be symmetrical in
pairs about a diametral plane of the cable being at a small
distance from said plane.
[0013] The cable advantageously also includes a reinforcing layer 6
between the tubular structure 2 and the outer sheath 3. This
reinforcing layer may be constituted by wires or elements having
high traction strength, e.g. made of aramid, glass fibers, or FRP
material, which are wound helically around the corrugated tubular
structure 2. In a variant, the reinforcing layer may also be
constituted by an annular layer extruded around the corrugated
tubular structure and preferably filled with reinforcing
fibers.
[0014] In this cable, the corrugated tubular structure 2 is strong
enough against radial stresses to serve simultaneously during
manufacture as a support for the extruded sheath and any
reinforcing layer without running any risk for the optical fibers
housed therein. Reference 8 designates a corrugation of the
corrugated tubular structure 2, not in section and situated behind
the section plane.
[0015] This corrugated tubular structure is made from a metal strip
which is corrugated transversely and rolled longitudinally to put
it into the form of a tube as it advances along the line. In a
variant, it may be made of a plastics material and it may be
extruded directly as a corrugated tube around the fibers. As it
advances down the line, it receives internally the optical fiber
ribbons or the optical fibers and also the filler material, and
externally it receives any reinforcing layer and the extruded outer
sheath provided with its reinforcing cords. The resulting optical
fiber cable is of unitube overall structure and it is thus obtained
directly in a single step, ignoring the manufacture of the optical
fiber ribbons when the optical fibers are in ribbon form.
* * * * *