NZ603030B - A central tube type optical fibre micro-cable - Google Patents
A central tube type optical fibre micro-cable Download PDFInfo
- Publication number
- NZ603030B NZ603030B NZ603030A NZ60303012A NZ603030B NZ 603030 B NZ603030 B NZ 603030B NZ 603030 A NZ603030 A NZ 603030A NZ 60303012 A NZ60303012 A NZ 60303012A NZ 603030 B NZ603030 B NZ 603030B
- Authority
- NZ
- New Zealand
- Prior art keywords
- optical fibre
- outer sheath
- central tube
- type optical
- tube type
- Prior art date
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Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/44—Mechanical structures for providing tensile strength and external protection for fibres, e.g. optical transmission cables
- G02B6/4401—Optical cables
- G02B6/4429—Means specially adapted for strengthening or protecting the cables
- G02B6/443—Protective covering
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/44—Mechanical structures for providing tensile strength and external protection for fibres, e.g. optical transmission cables
- G02B6/4401—Optical cables
- G02B6/4429—Means specially adapted for strengthening or protecting the cables
- G02B6/443—Protective covering
- G02B6/4432—Protective covering with fibre reinforcements
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/44—Mechanical structures for providing tensile strength and external protection for fibres, e.g. optical transmission cables
- G02B6/4479—Manufacturing methods of optical cables
- G02B6/4485—Installing in protective tubing by fluid drag during manufacturing
Abstract
603030 A central tube type optical fibre micro-cable is disclosed. The cable includes an outer sheath (4) with a loose polycarbonate (PC) tube (2) disposed in the outer sheath (4). Optical fibres or optical fibre bundles (1) can be inserted within the loose tube. The outer sheath (4) includes a plurality of circumferentially spaced longitudinally extending grooves and ridges to assist pneumatic installation by blowing. plurality of circumferentially spaced longitudinally extending grooves and ridges to assist pneumatic installation by blowing.
Description
A CENTRAL TUBE TYPE OPTICAL FIBRE MICRO-CABLE
FIELD OF THE INVENTION
The present invention relates to optical fibre cables and in particular to a central tube
type optical fibre micro-cable with high optical fibre density, and in which fibres are able to be
laid by a blowing-installation application or a JetNet type method in a pre-laid microplastic tube
or cable microduct. While some embodiments will be described herein with particular reference
to that application, it will be appreciated that the invention is not limited to such a field of use,
and is applicable in broader contexts.
BACKGROUND
With rapid development of fibre to the home (FTTH) installations in the field of
Metropolitan Area Networks (MANs) and Access Networks (ANs), the micro-cables have been
widely used in a blowing installation application by blown fibre laying methods. Due to
limitations of cable resources, particularly in built-up areas, standard industry demands favour
techniques focussing on convenience of use and access to long distances of blowing-
installation cables. Currently, blowing-installation cables have a similar structure to
conventional stranded type and central tube type cables. Conventional stranded type cables
have a relatively large diameter, generally limited to about 5 mm or larger. Consequently, fibres
can only be blown installed in these stranded type cables in tubes of size 10.0/8.0 mm (outer
/inner diameter). Currently used central tube type cables (used employed) have a relatively
smaller diameter, generally around 4 mm, and can typically be blown laid in tubes of size only
7.0/5.5 mm (outer inner diameter).
In many countries, the construction of FTTH is achieved through bundles of fibre
carrying tubes inserted into the fibre cables, which are in turn installed within cable microducts.
When laid, these tubes are generally subject to high mechanical strain. Therefore, the
supportive cables generally have one of two types of strength reinforcement structures: central
tube type structures; and glass bead or microsphere type structures.
The material used for central tube type structures is generally polybutylene
terephthalate (PBT), which is also used for loose tube designs. PBT undergoes retraction at
low temperatures and optical fibre transmission becomes unstable. Further, fibres can only be
subject to blown installation for short distances along PBT cables. Glass bead or microsphere
structured optical fibre cable have poor peeling capabilities and mechanical properties. These
two effects make this type of cable unfavourable for use in working environment which are
subject to high mechanical strain.
SUMMARY OF THE INVENTION
An object of the present invention, in its preferred form, is to provide a central tube
type optical fibre micro-cable that overcomes or alleviates the above-mentioned defects. This
type of cable is easy to install and use, has a simpler structure than other known designs and is
relatively low cost to manufacture.
According to one aspect, the present invention provides a central tube type optical
fibre micro-cable including:
an outer sheath; and
a loose tube disposed within the outer sheath;
wherein optical fibre bundles or optical fibres are able to be inserted within the loose
tube; and
wherein the loose tube is made of polycarbonate (PC) and the outer sheath includes a
plurality of circumferentially spaced longitudinally extending grooves.
The diameter of the outer sheath is preferably in the range 2.0 mm to 2.8 mm. The
diameter of the loose tube is preferably in the range 1.4 mm to 2.2 mm.
The central tube type optical fibre cable preferably includes a high tensile member
between the outer sheath and the loose tube.
The loose tube is preferably configured to contain optical fibre bundles having 2 to 24
optical fibres.
The outer sheath preferably includes 4 to 24 circumferentially spaced longitudinally
extending grooves. The maximum width of each groove is preferably in the range 0.05 mm to
0.8 mm and the radial depth of each groove is preferably in the range 0.05 mm to 0.8 mm.
According to the above solution, the outer sheath is made of a material that is
capable of reducing electrostatic absorption.
Reference throughout this specification to “one embodiment”, “some embodiments”
or “an embodiment” means that a particular feature, structure or characteristic described in
connection with the embodiment is included in at least one embodiment of the present
invention. Thus, appearances of the phrases “in one embodiment”, “in some embodiments” or
“in an embodiment” in various places throughout this specification are not necessarily all
referring to the same embodiment, but may. Furthermore, the particular features, structures or
characteristics may be combined in any suitable manner, as would be apparent to one of
ordinary skill in the art from this disclosure, in one or more embodiments.
DESCRIPTION OF DRAWINGS
Preferred embodiments of the invention will now be described, by way of example
only, with reference to the accompanying drawing in which:
Fig. 1 illustrates a cross-section of an embodiment of the present invention.
PREFERRED EMBODIMENT
A preferred embodiment of the present invention will now be described with reference
to the drawing.
Referring to Fig. 1, there is illustrated a central tube type optical fibre micro-cable that
can be inserted within cable microducts. The micro-cable includes an outer sheath 4 and an
inner loose tube 2 disposed within the outer sheath. Loose tube 2 is made of polycarbonate
(PC) material and has a diameter of 1.8 mm. Four optical fibre bundles, e.g. bundle 1, are
disposed within loose tube 2. Each optical fibre bundle 1 includes 2 to 24 optical fibres. Each
bundle is coloured differently for identification by technicians during installation or maintenance.
Loose tube 2 includes a water resistant lubricating fluid for reducing contact between the fibre
bundles and reducing electrostatic absorption. Outer sheath 4 is made of polyethylene (PE) for
reducing electrostatic absorption. Outer sheath 4 includes 16 circumferentially spaced
longitudinally extending substantially v-shaped grooves. The maximum width of each groove is
0.3 mm and the radial depth of each groove is 0.3 mm. A high tensile member 3 formed of
aramid yarn is disposed between outer sheath 4 and loose tube 2.
In some embodiments, loose tube 2 is able to contain greater or fewer than four
optical fibre bundles. In some embodiments, loose tube 2 includes a plurality of optical fibre
bundles, each having different numbers of optical fibres. In one embodiment, one or more
optical fibre bundles include greater than 24 optical fibres. In some embodiments, each fibre
bundle is marked with unique indicia to identify each bundle. In some embodiments, the optical
fibres within a bundle are individually coloured or marked to identify each specific fibre. In some
embodiments, outer sheath 4 is made of other materials capable of reducing electrostatic
absorption. In some embodiments, outer sheath 4 includes fewer than four grooves. In other
embodiments, outer sheath 4 includes greater than 16 grooves. In some embodiments, the
grooves have shapes other than the illustrated v-shaped grooves and different dimensions. In
some embodiments, high tensile member 3 is formed of high tensile materials other than
aramid yarn, including metals, alloys or plastics materials.
Advantages of the present invention include:
1) The loose tube formed of PC reduces tube retraction issues and also improves the
material transmission properties when compared to PBT tubes.
2) PC loose tubes with a small diameter and light weight permit the fibres to be blown
along the tube for a further distance than present tubes using a guide microduct of
about 5.0/3.5 mm (inner/outer diameter).
3) The longitudinal grooves of the outer sheath assists in:
a) Facilitating peeling of the cable when access to the inside of the cable is
required; and
b) Reducing the friction between the cable and the microduct wall during the
blowing process and to improve airflow smoothly.
4) Use of polyethylene or other materials that reduce electrostatic absorption aids in
reducing the blowing resistance during fibre blowing, which increases the distance that
cables can be blown.
) Compared with micro-optical cables having the same number of optical fibres, the
present invention reduces the complexity of the production process, requires fewer tube
material resources and saves cost.
It should be appreciated that in the above description of exemplary embodiments of
the invention, various features of the invention are sometimes grouped together in a single
embodiment, Fig., or description thereof for the purpose of streamlining the disclosure and
aiding in the understanding of one or more of the various inventive aspects. This method of
disclosure, however, is not to be interpreted as reflecting an intention that the claimed invention
requires more features than are expressly recited in each claim. Rather, as the following claims
reflect, inventive aspects lie in less than all features of a single foregoing disclosed
embodiment. Thus, the claims following the Detailed Description are hereby expressly
incorporated into this Detailed Description, with each claim standing on its own as a separate
embodiment of this invention.
Furthermore, while some embodiments described herein include some but not other
features included in other embodiments, combinations of features of different embodiments are
meant to be within the scope of the invention, and form different embodiments, as would be
understood by those skilled in the art. For example, in the following claims, any of the claimed
embodiments can be used in any combination.
In the description provided herein, numerous specific details are set forth. However, it
is understood that embodiments of the invention may be practiced without these specific
details. In other instances, well-known methods, structures and techniques have not been
shown in detail in order not to obscure an understanding of this description.
Thus, while there has been described what are believed to be the preferred
embodiments of the invention, those skilled in the art will recognize that other and further
modifications may be made thereto without departing from the spirit of the invention, and it is
intended to claim all such changes and modifications as fall within the scope of the invention.
For example, any formulas given above are merely representative of procedures that may be
used. Functionality may be added or deleted from the block diagrams and operations may be
interchanged among functional blocks. Steps may be added or deleted to methods described
within the scope of the present invention.
Claims (8)
1. A central tube type optical fibre micro-cable including: an outer sheath; and a loose tube disposed within the outer sheath; wherein optical fibre bundles or optical fibres are able to be inserted within the loose tube; and wherein the loose tube is made of polycarbonate (PC) and the outer sheath includes a plurality of circumferentially spaced longitudinally extending grooves.
2. A central tube type optical fibre micro-cable according to claim 1 wherein the diameter of the outer sheath is in the range 2.0 mm to 2.8 mm.
3. A central tube type optical fibre micro-cable according to claim 1 or claim 2 wherein the diameter of the loose tube is in the range 1.4 mm to 2.2 mm.
4. A central tube type optical fibre micro-cable according to any one of the preceding claims including a high tensile member disposed between the outer sheath and the loose tube.
5. A central tube type optical fibre micro-cable according to any one of the preceding claims wherein the loose tube is configured to contain optical fibre bundles having 2 to 24 optical fibres.
6. A central tube type optical fibre micro-cable according to any one of the preceding claims wherein the outer sheath includes 4 to 24 circumferentially spaced longitudinally extending grooves.
7. A central tube type optical fibre cable according to claim 6 wherein the maximum circumferential width of each groove is in the range 0.05 mm to 0.8 mm and the radial depth of each groove is in the range 0.05 mm to 0.8 mm.
8. A central tube type optical fibre micro-cable according to claim 6 or claim 7 wherein the outer sheath is formed of a material capable of reducing electrostatic absorption.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CN201120396823.2U CN202305943U (en) | 2011-10-18 | 2011-10-18 | Central-tube-type optical fiber bundle micro-cable |
CN201120396823.2 | 2011-10-18 |
Publications (2)
Publication Number | Publication Date |
---|---|
NZ603030A NZ603030A (en) | 2013-02-22 |
NZ603030B true NZ603030B (en) | 2013-05-23 |
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