Loose tube optical ribbon cable

Details Loose tube optical ribbon cable Loose tube optical ribbon cable

2002-09-05

2004-06-15

Patel, Tulsidas C. (Department: 2839)

Optical waveguides

Optical transmission cable

Loose tube type

Reexamination Certificate

active

06751383

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical-ribbon cable and more particularly to an optical-ribbon cable with loose tubes.
2. Description of the Related Art
Typically, optical-ribbon cables include optical-ribbon fibers as a transmission medium for optical signals. Optical-ribbon fibers are made of multiple cores of the optical fibers stranded in a single row and can be fabricated by stranding the multiple cores of the optical fibers in a single row, then sheathing them with UV-curable resin, followed by curing the UV-curable resin with UV. In addition, multiple optical-ribbon fibers can be laminated to compose a bundle of optical-ribbon fibers with a matrix structure. This type of optical-ribbon fibers has an advantage in that fiber density is very high in a limited space as multiple optical fibers are closely packed. As such, much attention is given to the use of high-density, optical-ribbon cables. The reason is that a large number of optical cables have been installed already in existing duct lines, so there is a shortage of space for the installation of new cables. Moreover, in view of efforts to reduce the outer diameters of optical cables or any increase in the packing density of optical fibers, the installation of such cables is ideal in the existing narrow ducts.
FIG. 1
is a cross-sectional view illustrating a configuration of a conventional loose-tube, optical-ribbon cable. The optical-ribbon cable comprises a central tensile-strength component
110
, a number of bundles of optical-ribbon fibers
120
, a plurality of loose tubes
130
, a tensile-strength component
140
, and an external sheath
150
.
As shown in
FIG. 1
, the central tensile-strength component
110
provides tensile strength for the loose-tube, optical-ribbon cable, thus situated in the center thereof. The loose tubes
130
are mounted with a bundle of optical-ribbon fibers
120
. The bundle of optical-ribbon fibers
120
has a matrix structure, where four or more cores of optical fibers are stranded in a single row and sheathed with UV-curable resin to form an optical-ribbon fiber, followed by lamination of multiple optical-ribbon fibers.
The tensile-strength component
140
surrounds the plurality of loose tubes
130
and performs a function of improving the tensile strength of the loose-tube, optical-ribbon cable. The external sheath
150
is formed using an extrusion process. The sheath comprises the outermost layer of the optical-ribbon cable so as to protect its interior against the external environment.
However, the above-described conventional loose-tube, optical-ribbon cable has drawbacks in that it has a poor resistance to moisture penetration and external stresses (pressure force, impact, etc). In addition, in terms of the physical appearance of the loose-tube, optical-ribbon cable, it is difficult to retain its original cross-sectional form because a hollow
160
is formed outside the pair of neighboring loose tubes
130
.
SUMMARY OF THE INVENTION
Therefore, the present invention overcomes the above-described problems and provides additional advantages, by providing a loose-tube, optical-ribbon cable, having improved water resistance and compression properties as well as exhibiting a good appearance.
In accordance with the present invention, the loose-tube, optical-ribbon cable includes a central tensile-strength component situated in the center of the optical-ribbon cable; a plurality of loose tubes mounted with a bundle of optical-ribbon fibers, the bundle of optical-ribbon fibers being formed by laminating multiple optical-ribbon fibers, each optical-ribbon fiber including multiple cores of optical fibers stranded in a single row and a sheath surrounding the multiple cores of optical fibers, the plurality of loose tubes being stranded around the central tensile-strength component; a plurality of circle-shaped, water-absorbing members arranged in a hollow which is formed outside a pair of the loose tubes neighboring each other; a water absorbing tape for surrounding the plurality of loose tubes and the plurality of circle-shaped, water-absorbing members; and, an external sheath situated in the outermost surface of the optical-ribbon cable for protecting the interior of the loose-tube, optical-ribbon cable against the external environment.


REFERENCES:
patent: 5229851 (1993-07-01), Rahman
patent: 5389442 (1995-02-01), Arroyo et al.
patent: 5621841 (1997-04-01), Field
patent: 5848212 (1998-12-01), Wagman
patent: 6088499 (2000-07-01), Newton et al.
patent: 6185351 (2001-02-01), Daneshvar et al.

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