Optical waveguides – Optical transmission cable – Tightly confined
Reexamination Certificate
1999-09-10
2001-07-10
Spyrou, Cassandra (Department: 2872)
Optical waveguides
Optical transmission cable
Tightly confined
C385S100000, C385S102000, C174S1170FF, C174S115000, C174S1170FF, C174S1170FF, C174S657000, C174S097000, C174S104000
Reexamination Certificate
active
06259843
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an optical cable, for example an optical cable which can be used in a work place such as an office building to connect a plurality of devices which receive and/or transmit data. The invention further relates to a method of laying the optical cable, and a data transfer system using the optical cable.
2. Description of the Prior Art
It is known to transmit data to, from or between devices (appliances) in a room such as an office using a data transfer system which employs electric cables laid under the flooring. Such a system can be easily modified to cope with an alteration of office layout, such as movement of devices or an increase in the number of devices.
In the above system, a wiring channel which is approximately U-shaped in section is provided under the flooring. The wiring channel is in the shape of a matrix or grid, and has lower and side surfaces which extend perpendicularly to each other. Electric cables (each containing a plurality of copper electric wires) for transmission of signals are laid along the wiring channel and run out of the wiring channel into the room at positions corresponding to locations where devices are installed.
Because of the increase in multiplex communication in recent years, there is a growing demand for an “optical composite” data transfer system which uses both electric cables and optical cables for transmission of signals. In such a system, one or more optical cables for optical communication are laid in the wiring channel alongside the electric wire cables.
FIG. 14
is a sectional view showing an optical cable
100
having a conventional construction. The optical cable
100
includes four optical fibers
102
twisted together around a reinforcing tension member
101
. A tape
103
is wound around the optical fibers
102
, and a plastics covering layer
104
provided for protection around the tape
103
. The tape
103
and the plastics covering layer
104
protect the optical fibers
102
from being subjected to external force.
However, the optical cable
100
as described above has a low degree of flexibility. Thus, the minimum permissible radius of curvature of the optical cable
100
may be as large as 100-120 mm. Thus, there are cases in which the optical cable
100
cannot be laid within a wiring channel formed in the shape of a matrix.
The optical cable
100
shown in
FIG. 14
has another problem because of its large diameter. For example, the optical cable
100
may be too wide to be inserted into a wiring channel which already accommodates an electric wire.
BRIEF SUMMARY OF THE INVENTION
The present invention addresses the above problems. It is an object of the present invention to provide an optical cable which can have sufficient flexibility and can be installed efficiently in a wiring channel. The invention provides an optical cable which can be appropriately accommodated in a right-angled corner region of a wiring channel, and which when located on a flat surface projects to a relatively low extent from that surface.
Further objects of the invention are to provide a new and useful method of laying an optical cable, and a data transfer system using an optical cable.
Accordingly, the present invention provides an optical cable, comprising at least one optical fiber and a cover surrounding the fiber. The cover has an outer surface which in cross-section is in the shape of a trapezium formed by removing the right-angled isosceles corner region from a right-angled isosceles triangle. The word “trapezium” is used here to mean a quadrilateral having one pair of parallel sides (in USA the word “trapezoid” has this meaning).
Thus, the optical cable can be laid in an installation space along a right-angled corner region defined at the junction of a pair of mutually perpendicular surfaces of the walls of the space with its two mutually perpendicular faces lying against these mutually perpendicular surfaces. Alternatively, it can be laid on a flat surface with the longer of its two parallel faces lying against the flat surface. Since the profile of the cover is a trapezium, in this second case it obstructs other objects to a lower degree than a triangular cable.
The optical fiber may consist of a core element surrounded by one or more jacket layers, or alternatively the optical fiber may consist of an optically transmissive element in direct contact with the cover. Typically the optically transmissive element is a core surrounded by one or more cladding layers.
Preferably, a groove extending in the longitudinal direction is formed on at least one main surface of the cover. The groove facilitates tearing of the cover, for example to gain access to one of the optical fibers.
Preferably, at least one reinforcing fiber is provided inside the cover extending in the longitudinal direction.
Preferably, an end portion of the optical fiber extends longitudinally beyond the cover, and this end portion of the optical fiber is attached to a connector.
In a second aspect, the invention provides a method of laying (installing) the optical cable according to the invention in a corner region or on a flat installing surface.
In a third aspect the invention provides a data transfer system which includes the optical cable according to the invention, optionally in combination with at least one electric data transfer cable.
REFERENCES:
patent: Re. 36592 (2000-02-01), Giebel
patent: 4815814 (1989-03-01), Ulijasz
patent: 5043531 (1991-08-01), Gutenson
patent: 5180890 (1993-01-01), Pendergrass et al.
patent: 5668912 (1997-09-01), Keller
patent: 0600108A1 (1992-11-01), None
patent: 0 600 108 (1994-06-01), None
patent: 1544203 (1968-09-01), None
patent: 1069666 (1967-05-01), None
Boutsikaris Leo
Oliff & Berridg,e PLC
Spyrou Cassandra
Sumitomo Wiring Systems Ltd.
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