Optical fibre ribbon structure

Claim 1

An optical fibre ribbon structure comprising a plurality of optical fibres and at least one flexible elongate reinforcing element of substantially resilient material arranged side by side and embedded in an elongate body of plastics material, wherein the resilient reinforcing element is set in such a form that the ribbon structure follows a path of smoothly curved undulations whose axes of curvature lie transverse to the longitudinal axis of the ribbon structure, the arrangement being such that, when the undulating ribbon structure is subjected to a tensile force, the ribbon structure straightens in a lengthwise direction against the action of the undulating resilient reinforcing element thereby reducing the tensile force applied to the optical fibres and when the tensile force is removed, the ribbon structure returns towards its original undulating form.

Claim 13

A method of manufacturing an undulating optical fibre ribbon structure comprising a plurality of optical fibres and at least one flexible elongate reinforcing element of substantially resilient material arranged side by side and embedded in an elongate body of plastics material, wherein the resilient reinforcing element is set in such a form that the ribbon structure follows a path of smoothly curved undulations whose axes of curvature lie transverse to the longitudinal axis of the ribbon structure, the arrangement being such that, when the undulating ribbon structure is subjected to a tensile force, the ribbon structure straightens in a lengthwise direction against the action of the undulating resilient reinforcing element thereby reducing the tensile force applied to the optical fibres and when the tensile force is removed, the ribbon structure returns towards its original undulating form, which method comprises causing a plurality of separate optical fibres and at least one flexible elongate reinforcing element of substantially resilient material to travel substantially side by side in the directions of their lengths with their axes lying in a substantially common plane; applying to the advancing optical fibres and to the advancing resilient reinforcing element an overall coating of a plastics material to form a plastics-coated reinforced optical fibre array; feeding the plastics-coated reinforced optical fibre array between a pair of advancing tapes; subjecting the advancing taped plastics-coated reinforced optical fibre array to a curing operation to cure the plastics material and cause it to bond both to the embedded optical fibres and resilient reinforcing element and lightly to the tapes; peeling the tapes away from the reinforced optical fibre array to form a reinforced optical fibre ribbon structure; and, before or after the tapes have been peeled away, causing the advancing ribbon structure to be partially wrapped around each of a plurality of transversely extending, longitudinally spaced formers of substantially at least partially circular cross-section travelling the the same direction as the advancing ribbon structure and at such a speed that there is substantially no relative movement between the advancing formers and the ribbon structure travelling therebetween, the direction of wrap around one former being in the opposite circumferential direction to the direction of wrap around the or each adjacent former and the circumferential extent of wrap around each of the formers being such that the resilient reinforcing element is set in such a form that the optical fibre ribbon structure follows a path of smoothly curved undulations whose axes of curvature lie transverse to the longitudinal axis of the ribbon structure.

Claim 14

A method of manufacturing an undulating optical fibre ribbon structure comprising a plurality of optical fibres and at least one flexible elongate reinforcing element of substantially resilient material arranged side by side and embedded in an elongate body of plastics material, wherein the resilient reinforcing element is set in such a form that the ribbon structure follows a path of smoothly curved undulations whose axes of curvature lie transverse to the longitudinal axis of the ribbon structure, the arrangement being such that, when the undulating ribbon structure is subjected to a tensile force, the ribbon structure straightens in a lengthwise direction against the action of the undulating resilient reinforcing element thereby reducing the tensile force applied to the optical fibres and when the tensile force is removed, the ribbon structure returns towards its original undulating form, which method comprises causing a plurality of separate optical fibres and at least one flexible elongate reinforcing element of substantially resilient material to travel substantially side by side in the directions of their lengths with their axes lying in a substantially common plane; applying to the advancing optical fibres and to the advancing resilient reinforcing element an overall coating of a plastics material to form a plastics-coated reinforced optical fibre array; feeding the plastics-coated reinforced optical fibre array between a pair of advancing tapes; subjecting the advancing taped plastics-coated reinforced optical fibre array to a curing operation to cure the plastics material and cause it to bond both to the embedded optical fibres and resilient reinforcing element and lightly to the tapes; peeling the tapes away from the reinforced optical fibre array to form a reinforced optical fibre ribbon structure; and, before or after the tapes have been peeled away, causing the advancing ribbon structure to be partially wrapped around each of a plurality of transversely extending, longitudinally spaced formers of substantially at least partially circular cross-section travelling the the same direction as the advancing ribbon structure and at such a speed that there is substantially no relative movement between the advancing formers and the ribbon structure travelling therebetween, the direction of wrap around one former being in the opposite circumferential direction to the direction of wrap around the or each adjacent former and the circumferential extent of wrap around each of the formers being such that the resilient reinforcing element is set in such a form that the optical fibre ribbon structure follows a path of smoothly curved undulations whose axes of curvature lie transverse to the longitudinal axis of the ribbon structure.