Flattened Optical Fiber Cable Sheath for Airtightness and Diameter Control
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Solution Overview
Problem
Existing optical fiber cables face issues with sheath damage and increased diameter when pressure is applied due to insufficient thickness of the tensile strength member sheaths, which affects airtightness and pumping distance.
Innovation Solution
The optical fiber cable design features a flattened sheath structure where the tensile strength member is positioned to overlap with the sheath's long axis, maintaining a circularity of 85% to 96%, ensuring the TM inner sheath is thick enough to prevent damage while reducing the overall cable diameter.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the sheath thickness is increased to increase the thickness of the TM outer sheath and TM inner sheath, then the sheath is less likely to be damaged and airtightness is improved, but the average outer diameter of the cable increases
Solution Approach 1:
The patent applies local quality by making the sheath thickness non-uniform. Specifically, the sheath is designed with a first thickness in a first region and a second thickness smaller than the first thickness in a second region. This allows the TM outer sheath and TM inner sheath to have sufficient thickness in critical areas for damage resistance and airtightness, while reducing the overall cable diameter by thinning the sheath in non-critical regions.
2Reliability
If the circularity of the sheath surface layer is increased to improve airtightness with the cable pump, then the pumping distance can be extended, but the sheath becomes more prone to damage when pressure is applied
Solution Approach 1:
The patent resolves this contradiction by implementing local quality through region-specific thickness design. The sheath has a first thickness in a first region that provides sufficient circularity (85% or more) for good airtightness and extended pumping distance, while the second region has a reduced thickness to minimize overall cable diameter. This selective thickness distribution allows the cable to achieve both good airtightness and reduced vulnerability to pressure-induced damage.
Data Source
AI summary
An optical fiber cable includes a cable core including a plurality of optical fibers, at least one tensile strength member provided along an axis of the cable core, and a sheath covering the cable core from an outside and containing the tensile strength member. The sheath is flattened such that a long axis of the sheath overlaps a position where the tensile strength member is provided with respect to the cable core, in a cross-sectional view orthogonal to an axis of the optical fiber cable. A circularity of an outer diameter of the cable core is larger than a circularity of a surface layer of the sheath. The circularity of the surface layer of the sheath is 85% or more and 96% or less, in the cross-sectional view.