Construction of cable made of optical fibres
AssigneeGeneral Cable Corporation
InventorLudwik Jachimowicz
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Abstract
This invention is a fibre optic communication cable in which the signals are transmitted by light. The glass fibres used for the cable are protected from breaking strain and from excessively sharp bends by supporting helically wound optic fibres on the inside of a tension element with provision by which the diameters of the helical convolutions can become smaller to increase the axial length component of the optic fibres when the a axial length of the tube is increased by forces that strain the tube. Several ways of maintaining the helically wrapped optic fibres supported from the tube so as to permit decrease in the diameter of the helix are described and illustrated.
Claims17
An optic fibre communication cable comprising a hollow protective tube, optic fibres within the tube and extending lengthwise of the tube along substantially helical paths of substantially equal diameter and longitudinally spaced from one another and adjacent to the inside wall of the tube, the optic fibres being held on one side of a stiffly flexible strip of material that is wrapped into an open helix within the tube, said tube enclosing a space immediately inward of the optic fibres around substantially the entire diameter of the helical paths so as to leave an open space into which the fibres move as the cable increases in length under tension loading and the helical convolutions of the strip decrease in diameter with resulting decrease in the diameter of the helical paths of the fibres, the optic fibres being under negligible stress in the tube and the decrease in the diameter of the helical strip preventing stressing of the optic fibres when the protective tube of the cable is elongated by the tension loading, said strip having sufficient resilience to spring back to its original convolution diameter when the tension loading on the tube are relieved.
The method of making a fibre optic communication cable which comprises wrapping optic fibres around a mandrel, removing the mandrel and leaving the optic fibres along a helical path, placing a protecting tube and tension resisting element around the outside of the helical path and close to the optic fibres, and leaving empty space within the tube immediately inward of the optic fibres around substantially the entire inside diameter of the helical paths so as to leave an air-filled space into which the helical convolutions can move to decrease the diameter of the convolutions if the cable is elongated by tension force on said tube.
Dependencies are inferred from the claim text.