Optical Fiber Cable Recesses for Low-Temperature Shrinkage
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Solution Overview
Problem
Existing slotless-type optical fiber cables face challenges in maintaining a sufficient pull-out force and reducing packing density while keeping the outer diameter within limits, which can lead to defective products and transmission characteristic deterioration due to shrinkage at low temperatures.
Innovation Solution
The optical fiber cable design incorporates a sheath with recesses on its inner surface, forming spaces between the wrapping tube and the sheath, along with tensile strength members and protrusions, to reduce packing density while maintaining the outer diameter and pull-out force, and includes a wrapping tape configuration that enhances the structural integrity and deformation capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the packing density of the optical fiber is reduced to suppress deterioration of transmission characteristics at low temperatures, then the transmission reliability is improved, but the pull-out force of the optical fiber decreases
Solution Approach 1:
The sheath is designed with recesses at specific locations to create localized spaces that provide buffer room for optical fibers. This local modification allows the optical fibers to be positioned away from the sheath wall in critical areas, reducing the risk of transmission characteristic deterioration due to shrinkage, while maintaining adequate contact and friction in other areas to preserve pull-out force.
Solution Approach 2:
The recesses are formed by removing material from the sheath in the radial direction, creating three-dimensional spaces within the sheath structure. This dimensional approach allows the optical fibers to be positioned within these recesses, providing clearance from the outer sheath wall while maintaining overall cable compactness and preserving frictional engagement for pull-out resistance.
2Reliability
If the outer diameter of the optical fiber cable is increased to lower the packing density, then the transmission reliability is improved, but the cable cannot be installed in existing ducts
Solution Approach 1:
The sheath is segmented by forming multiple recesses distributed around its circumference. These recesses create localized void spaces that effectively increase the internal volume available for optical fiber placement without increasing the outer diameter of the cable, thereby maintaining compatibility with existing duct infrastructure.
Solution Approach 2:
The sheath structure incorporates recesses that create a porous-like configuration with distributed void spaces. This allows the sheath to provide adequate clearance and buffer room for optical fibers while maintaining a compact outer diameter that fits within existing duct constraints.
3Reliability
If the packing density of the optical fiber is reduced to prevent shrinkage effects, then the transmission reliability is improved, but the structural integrity and pull-out resistance deteriorate
Solution Approach 1:
The recesses are strategically positioned and sized to provide local buffer zones where optical fibers can accommodate shrinkage movements without compromising overall cable structure. The remaining portions of the sheath maintain full contact with the wrapping tube and optical fibers, preserving frictional engagement and structural integrity for pull-out resistance.
Solution Approach 2:
The recesses act as pre-formed buffer zones that anticipate and accommodate the effects of thermal shrinkage. By providing these spaces in advance, the optical fibers can move within the recesses during temperature variations without exerting excessive stress on the cable structure, thereby preventing transmission characteristic deterioration while maintaining overall structural strength.
Data Source
AI summary
An optical fiber cable includes optical fibers, a wrapping tube that wraps around the optical fibers and contacts outermost ones of the optical fibers, and a sheath that covers the wrapping tube and has recesses on an inner circumferential surface of the sheath. The recesses are recessed toward a radially outer side of the optical fiber cable such that a space exists between the wrapping tube and the sheath in each of the recesses.