Optical Fiber Cable With Asymmetric Sheath for Small-Diameter Bends
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Solution Overview
Problem
Optical fiber cables exhibit bending anisotropy and buckling issues when bent to small diameters, leading to reduced bending rigidity and increased space requirements, especially with thinner sheaths, which compromise protection and density.
Innovation Solution
The optical fiber cable features a non-circular cable core with varying sheath thickness, where the thickness around the tensile strength member is greater than the thickness facing it, allowing for a smaller diameter and higher density while reducing buckling and improving flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the sheath is made thinner to increase optical fiber density, then the cable diameter is reduced, but the protective function is reduced and tensile strength members are more likely to buckle
Solution Approach 1:
The sheath thickness is made non-uniform, with a first sheath thickness at the location containing the tensile strength member and a second sheath thickness at the opposite location. The first sheath thickness is greater than the second sheath thickness, providing enhanced protection where the tensile strength member is located while maintaining overall reduced cable diameter.
2Strength
If three or more tensile strength members are arranged at equal intervals on the sheath, then the cable has improved tensile strength, but the distance from the bending center is large causing buckling and requiring large storage space
Solution Approach 1:
Instead of arranging tensile strength members symmetrically at equal intervals, the patent uses a non-circular cable core with a single tensile strength member located at a specific position. This asymmetric arrangement reduces the distance from the bending center, improving flexibility and reducing storage space requirements while maintaining adequate tensile strength.
Solution Approach 2:
The patent divides the sheath into regions of different thicknesses, with a first sheath thickness at the tensile strength member location and a second sheath thickness at the opposite location. This segmentation allows optimized protection and reduced overall diameter.
3Stability of the object's composition
If the cable core is a perfect circle with uniform sheath thickness, then the cable has symmetric structure, but the diameter is large and optical fiber density is reduced
Solution Approach 1:
The patent abandons the symmetric circular cable core design in favor of a non-circular cable core with varying sheath thickness. This asymmetric design reduces the overall cable diameter and increases optical fiber density while providing targeted protection at the tensile strength member location.
Solution Approach 2:
The sheath thickness is varied locally, with a first sheath thickness at the tensile strength member location and a second sheath thickness at the opposite location. This allows the cable to have reduced overall diameter while maintaining adequate protection where needed.
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 the cable core, and a sheath covering the cable core from an outside of the cable core and containing the tensile strength member. The cable core has a non-circular shape. In a cross-sectional view, when a thickness of the sheath at a location where the thickness of the sheath is the largest at a position including the tensile strength member is defined as a first sheath thickness, and a thickness of the sheath at a position facing the tensile strength member across the cable core is defined as a second sheath thickness, the first sheath thickness is larger than the second sheath thickness.