Optical waveguides – Integrated optical circuit
Reexamination Certificate
1998-08-13
2001-08-07
Ngo, Hung N. (Department: 2874)
Optical waveguides
Integrated optical circuit
C385S114000, C385S121000, C385S049000, C385S080000
Reexamination Certificate
active
06272263
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a fibre optic routing system for routing a plurality of fibre optic cables.
PRIOR ART
Routing boards are known, for example, from U.S. Pat. No. 5,204,925 (Bonanni et al.), assigned to AT&T Bell Laboratories, Murray Hill, N.J. It is known that optical fibres incorporated into such routing boards are very fragile and can be broken easily when put under stress. One weak link in such routing boards is the connection at the edge of the routing boards where the optical fibres are connected to the outside world. The connecting element is often placed under both lateral and transverse stresses and thus may be easily damaged.
From pending U.S. Ser. No. 08/880,965 filed Jun. 23, 1997 (Schricker) a laminate for use in opto-electronic devices is known which is compressible and also resistant to mechanical stresses. The use of the taught laminate for a routing board connecting element is, however, not disclosed in this patent.
Connectors for attachment to optical fibres are known from U.S. Pat. No. 4,678,264 (Bowen et al.) assigned to AMP Inc. and from U.S. Pat. No. 4,998,796 (Bonanni et al.) assigned to AT&T Bell Laboratories. Neither of these document disclose, however, a connection to a routing board.
SUMMARY OF THE INVENTION
The object of the invention is therefore to improve the mechanical connection between a fibre optic routing board and a fibre optic cable.
A further object of the invention is to protect the optical fibres in the routing board from mechanical stress.
These and other objects of the invention are achieved by providing a fibre optic routing system with one or more optical conductors disposed between a first lower laminate layer and a first upper laminate layer, the one or more optical conductors being connected to at least one of the optical fibres in the plurality of fibre optic cables, wherein at least one of the first lower laminate layer or the first upper laminate layer is so constructed that it attaches at least one of a jacket over a first. By means of this construction, a mechanically strong bond is achieved between the laminate of the fibre optic routing board and the jacket of the fibre optic cable which reduces the risk that the fibre optic cable becomes separated from the fibre optic routing board when transverse or longitudinal stresses are applied to the fibre optic cable or the routing board. For the strongest joint, the jacket is preferably attached to both the first lower laminate layer and the first upper laminate layer.
Advantageously, the fibre optic routing board additionally comprises a second laminate layer positioned between the first upper or lower laminate layer and the optical conductors. The use of a two layer laminate allows each of the laminate layers to have different properties. Thus one layer might reduce transverse stresses on the connecting element and enclosed optical fibre whilst another layer might reduce longitudinal stresses on the connecting element and enclosed optical fibre.
In one embodiment of the invention, the jacket is attached to said second laminate layer over a second distance, thus additionally providing a mechanically strong bond between the fibre optic cable and the second laminate layer.
In another embodiment of the invention, an extension extends from the edge of said second laminate layer to a third distance within said jacket tube. This construction allows the second lamiante to be used to buffer the optical fibres within the fibre optic cable. It substantially improves the strength of the connection between the fibre optic cable and the fibre optic routing board since part of the routing board becomes part of the fibre optic cable.
The fibre optic cable has preferably reinforcement which is attached to said first upper laminate layer and/or said first lower laminate layer over a fifth distance and said second laminate layer over a sixth distance. This further improves the mechanical strength of the connection between the routing board and the fibre optic cable.
Preferably the fibre optic cable includes a buffering layer positioned between the reinforcement tube and the at least one of said optical conductors for buffering the optical conductors within the fibre optic cable.
In a preferred embodiment of the invention the first upper laminate layer and/or the first lower laminate layer and/or the second laminate layer comprise at least a first compressible layer and/or a mechanically resistant layer. The compressible layer is used to to improve the crush resistance of the routing board whilst the mechanically resistant layer improves the tolerance of the routing board to tensile forces. Preferably the compressible layer is made from expanded polytetrafluoroethylene (PTFE), foamed polyurethane, silicones and foamed polyethylene and the mechanically resistant layer is made from expanded PTFE, polyester, polyamide, or polyimide.
In a further embodiment of the invention a compressible layer is provided between the one or more optical conductors in order to protect the optical fibre conductors.
In one aspect, the routing system is a fibre optic routing system for routing a plurality of fibre optic cables comprising:
a plurality of fibre optic cable, each having at least one optical fibre surrounded by ajacket; and
a routing board with a first lower laminate layer situated below a first upper laminate layer, one or more optical conductors disposed between said first lower laminate layer and said first upper laminate layer, the one or more optical conductors being connected to at least one of the optical fibres in one of the plurality of fibre optic cables, wherein at least one of said first lower laminate layer or said first upper laminate layer is so constructed that it attaches at least one of the jacket over a first distance surrounding at least one of said optical fibres.
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Ngo Hung N.
Wheatcraft Allan M.
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