TECHNICAL FIELD
The present invention generally relates to optical fiber cables. In
particular, the present disclosure relates to aerial optical fiber cable with minimal
5 diameter and optimized tensile strength.
BACKGROUND OF THE DISCLOSURE
The following description of the related art is intended to provide
background information pertaining to the field of the disclosure. This section
may include certain aspects of the art that may be related to various features of
10 the present disclosure. However, it should be appreciated that this section is
used only to enhance the understanding of the reader with respect to the
present disclosure, and not as admissions of the prior art.
As a result of the rapid transformation of telecommunications services,
which has increased the volume of data transmission and higher bandwidth
15 requirements, it has become necessary to increase the fiber count in the cables
beyond 48 fibers to 72, 96 or even higher fibers in order to support nextgeneration services such as FTTH and 5G mobility and to provide better
connectivity between infrastructures quickly and affordably. It is common to lay
these cables aerially, leveraging existing poles for deployment of optical fiber.
20 However, cables that are suspended in the air are susceptible to external threats
like road accidents, falling trees, ice storms or high winds, etc. In such
circumstances, optical cables must be engineered to cause minimal
infrastructure damage, no human casualties, and minimal external impact
damage. High tensile strength and crush resistance of cable can prevent cable
25 breakage in these conditions, but if the cable failed to break in severe conditions,
it could cause the corresponding pole structures to collapse and possibly cause
damage to property and threaten the lives of people. Due to the potential risk to
life and property, tensile strength is a crucial mechanical characteristic of any
aerial cable. However, cables with too low a tensile strength could break too
3
easily, resulting in frequent repairs, which will cost money and cause protracted
network outages in the affected area.
Furthermore, in rural areas, suburban areas, and along railroad rights-ofway, the cheapest and most suitable way to deploy optical fiber cable
5 infrastructure to increase the network of telecommunication and connectivity is
to install self-supporting aerial cables on existing telephone/telegraph poles.
However, large and heavy cables may only be placed after pole inspection,
followed by pole reinforcement or replacement.
To achieve an adequate point of breakage and to meet future
10 communication requirements, an optical fiber cable with a high fiber density and
optimised tensile strength is required.
SUMMARY OF THE DISCLOSURE
This section is provided to introduce certain objects and aspects of the
present invention in a simplified form that are further described below in the
15 detailed description. This summary is not intended to identify the key features or
the scope of the claimed subject matter.
An object of the present invention is to provide a high density optical
fiber cable with higher fiber count and reduced outer diameter, which can be
suspended aerially and does not require any change to the current infrastructure
20 setting, in order to overcome at least some of the drawbacks mentioned in the
previous section and those otherwise known to persons skilled in the art.
Another object of the present invention is to provide an optical fiber cable that
reduces repair needs and minimizes network outages with corresponding cost
benefits. Another object of the present disclosure is to provide an optical fiber
25 cable that has optimized tensile strength sufficient to support short-span
installations but that breaks in the event of any unforeseen circumstance to
prevent any damage to the infrastructure it has been suspended on. Another
object of the present disclosure is to provide an optical fiber cable that has a high
optical fiber density.
4
Furthermore, in order to achieve the aforementioned objectives, the
invention provides an optical fiber cable comprising an outer sheath; plurality of
easily peelable sleeves enclosing plurality of optical fibers; and at least two
5 strength members suspended linear to an axis of the optical fiber cable, wherein
the optical fiber cable has breaking strength between 1300 and 2000 N.
BRIEF DESCRIPTION OF DRAWINGS
The accompanying drawings, which are incorporated herein, and
constitute a part of this disclosure, illustrate exemplary embodiments of the
10 invention in which like reference numerals refer to the same parts throughout
the different drawings. Components in the drawings are not necessarily to scale,
emphasis instead being placed upon clearly illustrating the principles of the
present disclosure.
Figure 1A is a cross sectional view of the optical fiber cable, in accordance
15 with exemplary embodiments of the present disclosure.
Figure 1B is a longitudinal sectional view of the optical fiber cable, in
accordance with exemplary embodiments of the present disclosure.
The foregoing shall be more apparent from the following more detailed
description of the disclosure.
20 DESCRIPTION OF THE INVENTION
In the following description, for the purposes of explanation, various
specific details are set forth in order to provide a thorough understanding of
embodiments of the present disclosure. It will be apparent, however, that
embodiments of the present disclosure may be practiced without these specific
25 details. Several features described hereafter can each be used independently of
one another or with any combination of other features. An individual feature
may not address any of the problems discussed above or might address only
some of the problems discussed above.
5
The ensuing description provides exemplary embodiments only, and is
not intended to limit the scope, applicability, or configuration of the disclosure.
Rather, the ensuing description of the exemplary embodiments will provide
those skilled in the art with an enabling description for implementing an
5 exemplary embodiment. It should be understood that various changes may be
made in the function and arrangement of elements without departing from the
spirit and scope of the disclosure as set forth.
Specific details are given in the following description to provide a
thorough understanding of the embodiments. However, it will be understood by
10 one of ordinary skill in the art that the embodiments may be practiced without
these specific details.
The word “exemplary” and/or “demonstrative” is used herein to mean
serving as an example, instance, or illustration. For the avoidance of doubt, the
subject matter disclosed herein is not limited by such examples. In addition, any
15 aspect or design described herein as “exemplary” and/or “demonstrative” is not
necessarily to be construed as preferred or advantageous over other aspects or
designs, nor is it meant to preclude equivalent exemplary structures and
techniques known to those of ordinary skill in the art. Furthermore, to the extent
that the terms “includes,” “has,” “contains,” and other similar words are used in
20 either the detailed description or the claims, such terms are intended to be
inclusive—in a manner similar to the term “comprising” as an open transition
word—without precluding any additional or other elements.
As disclosed in the background section, existing technologies have many
limitations, and in order to overcome at least some of the limitations of the prior
25 known solutions, the present disclosure provides a nominal diameter and high
fiber count optical fiber cable having a break strength in the range of 1300 to
2000N. Furthermore, a linearly suspended strength member is disclosed, which
enables the optical fiber cable to be used in the most efficient manner. The
optical fiber cable comprises a substantially round flexible outer sheath, one or
6
more easily peelable sleeve comprising plurality of optical fibers, and one or
more linearly suspended strength members.
Referring now to FIG. 1A, where a cross sectional view of the optical
fiber cable is disclosed, the optical fiber cable [100] (also referred to as optical
5 cable or fiber cable or simply as cable, and all the terms are used interchangeably
hereinafter), which has a circular cross section, includes a substantially round,
flexible outer sheath [102] enclosing multiple easily peelable sleeves[106]
surrounding one or more optical fibers [104]. The outer sheath [102] may be
made of polyethylene material such as High Density Polyethylene (HDPE).
10 For instance, the optical fiber cable [100] may include four easily peelable
colour coded sleeves [106], wherein each sleeve comprises 24 fibers each. These
easily peelable colour coded sleeves [106] may be twisted/stranded together
with either a continuous or reverse oscillating lay twist. The easily peelable
sleeves [106] are made of soft material a thermoplastic urethane or a low smoke
15 zero halogen compound that can be easily peeled with bare hand without
requiring any tools. The soft material has a hardness less than 60 Shore D.
Further, the easily peelable sleeves has, a nominal thickness of 0.2mm or less In
another embodiment, the easily peelable sleeves has a nominal thickness in
range of 0.1 mm to 0.3 mm.
20 Further, one or more sleeves include water blocking element to prevent
ingression of water or moisture within the sleeves. The water blocking element is
selected from group including water blocking gel, water-swellable powder, water
swellable yarn or tape.
The optical fiber cable [100] also contains at least one water swellable
25 yarns [110] enclosed within the outer sheath [102] to prevent ingression of
water or moisture within the cable. In yet another embodiment, the outer
sheath [102] encloses one or more water swellable tapes.
Also, the optical fibers [104] have a nominal cladding diameter of 125um.
In an alternate embodiment, optical fibers [104] have a nominal cladding
7
diameter less than 125um, with a nominal cladding diameter in a preferred
embodiment is between 80 and 100 um. . Further, the optical fiber cable [100]
as disclosed by the present disclosure may include optical fiber cable with 60, 72,
96, 120, 144 and 192 fibers. Furthermore, in an implementation of the present
5 disclosure, optical fiber cable [100] may have more than 192 fibers.
Preferably, the outer diameter of the coated and colored fibers is smaller
than 215um. In a more preferred embodiment, the optical fibers [104] have an
outer diameter in the range from 160 to 200 um. In other embodiment optical
fibers [104] has outer diameter of 200 +/- 15 um.
10 Further, the optical fiber cable [100] includes at least two strength
members [108] suspended linear to an axis of the optical fiber cable [100]. These
strength members [108] are coated or surrounded with an anti-corrosion layer.
The anti-corrosion layer is selected from a group comprising brass, chrome,
ethylene-acrylic acid copolymer, propylene-acrylic acid copolymer, and
15 phosphate compounds.
In an exemplary embodiment, the strength members [108] comprise a
pair of steel wires stranded together to form the single strength member [108].
In an exemplary implementation of this embodiment, each wire within the pair
has an outer diameter of 0.3 +/- 0.05 mm. In an exemplary embodiment, the
strength member [108] has total cross sectional area less than 0.40 mm2 20 .
In an embodiment, more than one strength members [108] are
embedded in the outer sheath [102]. In a preferred embodiment, two strength
members [108] are embedded in the outer sheath [102], and placed
diametrically opposite to each other.
25 The optical fiber cable [100] of the present invention has breaking
strength between 1300 and 2000 N and a nominal outer diameter not larger
than 7.0mm. In a preferred embodiment, the nominal outer diameter is around
7.0 +/- 0.2 mm. Further, the optical fiber cable [100] of the present invention has
a nominal weight around 36.0 +/- 10% Kg/Km.
8
In an exemplary implementation, a 96 fiber cable encloses four colourcoded easily peelable sleeves [106]. Each sleeve [106] encloses 24 fibers with a
nominal cladding diameter of 125um and an outer diameter of 200 +/-15 um. In
5 another embodiment, the fibers [104] have nominal cladding diameter in range
of 80 to 100 um. In an alternate embodiment, the fibers [104] have nominal
outer diameter of 160 to 200 um. Further, each fiber [104] within the sleeves
[106] are uniquely identifiable by unique colour coating. In case of more than 12
fibers are enclosed within the sleeves [106], ring marking is used over the fibers
10 [104] for unique identification. In an embodiment, single ring-marking is done on
natural fibers instead of fibers already colored with a black color or any other
color.
The exemplary cable [100] has a fiber strain less than 0.67% at the
maximum environmental load of around 950N and a consistent break strength
15 less than 2000N. In a preferred embodiment, the exemplary cable [100] has a
fiber strain around 0.63% at the maximum environmental load of around 950N
and a consistent break strength around 1850N.
In another exemplary implementation, a 72 fiber cable encloses three
sleeves containing 24 fibers each. In an alternate embodiment, a 72 fiber cable
20 encloses six sleeves containing 12 fibers each. Each fiber [104] has a nominal
cladding diameter around 125um and an outer diameter of 200 +/-15um. In
another embodiment, the fibers [104] have nominal cladding diameter in range
of 80 to 100 um. In an alternate embodiment, the fibers [104] have nominal
outer diameter between 160 to 200 um.
25 Referring now to FIG. 1B, where a cross-longitudinal view of the optical
fiber cable is disclosed. The optical fiber cable [100] (also referred to as optical
cable or fiber cable or simply as cable, and all the terms are used interchangeably
hereinafter), which has a substantially circular cross section, includes a
substantially round, flexible outer sheath [102] enclosing one or more sleeves.
9
The outer sheath [102] may be made of polyethylene material such as
HDPE(High-density polyethylene). The outer sheath has a nominal thickness
around 1.3 mm.
The optical fibers [104] are surrounded by easily peelable colour coded
5 sleeves [106]. These easily peelable colour coded sleeves [106] are
twisted/stranded together with either a continuous or a reverse oscillating lay
twist. The twisting/stranding of the sleeves averages out the strains on the
sleeves, which allows the cable [100] to bend at a relatively low bend radius. In
addition, twisting can limit micro-bending attenuation by providing the sleeves
10 with a well-defined path.
The optical fiber cable [100] also contains at least one water swellable
yarns [110] enclosed within the outer sheath [102] to prevent ingression of
water or moisture within the cable. In yet another embodiment, the outer
sheath encloses water swellable tape. Also, each sleeve [106] include a plurality
15 of optical fibers[104].
Further, the optical fiber cable [100] includes at least one strength
member [108] suspended linear to an axis of the optical fiber cable [100]. The
strength members [108] are coated or surrounded with an anti-corrosion layer to
prevent the formation of rust.
20 In an embodiment, the strength member [108] comprises a pair of steel
wires stranded together to form the single strength member.
In an embodiment, more than one strength members are embedded in
the outer sheath [102]. In a preferred embodiment, two strength members are
embedded in the outer sheath in diametrically opposite position.
25 The optical fiber cable of the present invention has breaking strength
between 1300 and 2000 N and a nominal outer diameter not larger than 7.0mm.
30
10
We Claim:
1. An optical fiber cable [100] comprising –
- at least one substantially round, outer sheath [102];
5 - a plurality of easily peelable sleeves [106], wherein each sleeve [106]
encloses a plurality of optical fibers [104], wherein each optical fiber
[104] has a nominal outer diameter between 160 to 215 um; and
- at least two strength members [108] suspended linear to an axis of the
optical fiber cable [100],
10 wherein the optical fiber cable [100] has breaking strength between 1300
and 2000 N.
2. The optical fiber cable [100] as claimed in claim 1, wherein each strength
member [108] comprises at least two stranded steel wires.
15
3. The optical fiber cable [100] as claimed in claim 1, wherein strength
members [108] are embedded within the outer sheath[102].
20 4. The optical fiber cable [100] as claimed in claim 2 wherein each steel wire
of the at least two stranded steel wires has a diameter of 0.30 +/- 0.05
mm.
5. The optical fiber cable [100] as claimed in claim 1, wherein the optical
25 fiber cable [100] has a nominal outer diameter not larger than 7.0mm and
a nominal weight of 36.0 +/- 10% Kg/Km.
6. The optical fiber cable [100] as claimed in claim 1, wherein each optical
fiber [100] has a nominal cladding diameter between 80 to 100 um.
11
7. The optical fiber cable [100] as claimed in claim 1, wherein the optical
fiber cable [100] has a fiber strain less than 0.67% at maximum
environmental load.
5
8. The optical fiber cable [100] as claimed in claim 1, wherein the easily
peelable sleeves [106] are made of a material having a hardness less than
60 Shore D.
10 9. The optical fiber cable [100] as claimed in claim 1, wherein the easily
peelable sleeves [106] have a nominal thickness of 0.2 mm or less.
10. The optical fiber cable [100] as claimed in claim 1, wherein the optical
fibers [104] are ring marked if a number of optical fibers [104] within
15 each sleeve [106] are more than 12.