Flat Optical Drop Cable Stadium Cavity Design
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Solution Overview
Problem
Traditional flat optical drop cables face issues with fiber migration and stress due to environmental loads, leading to signal attenuation and reduced flexibility, particularly at extreme temperatures, and have larger dimensions and higher volumes compared to newer designs.
Innovation Solution
A flat optical drop cable design featuring a stadium-shaped cavity with oscillating optical fibers retained within the sheath, using strength members embedded or inside the cavity, and a sinusoidal or zig-zag oscillation pattern to minimize fiber migration and maintain flexibility without inducing stress on the fibers, resulting in a reduced size and volume while maintaining performance under tensile loads and temperature variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large strength members with high Young's modulus and low coefficient of thermal expansion are used to withstand strains, then the cable can withstand environmental loads without inducing stresses on optical fibers, but the cable dimensions increase
Solution Approach 1:
The patent changes the material parameters by using strength members with specific Young's modulus (10-100 GPa) and coefficient of thermal expansion (5-15 ×10^-6/°C) values that balance mechanical strength with thermal compatibility. This allows the cable to withstand environmental loads while maintaining compact dimensions and preventing fiber stress from thermal expansion differences.
Solution Approach 2:
The patent employs composite cable construction combining outer sheath material (PE or PP) with strength members having specific mechanical and thermal properties. This composite structure achieves both strain resistance and dimensional compactness by optimizing the material combination rather than relying on single-material solutions.
2Device complexity
If optical fibers are housed directly within the channel or cavity without being retained by the jacket, then the cable structure is simplified, but the optical fibers may migrate within the channel or cavity causing tension in connectors or splices
Solution Approach 1:
The patent introduces an oscillating channel structure that dynamically adapts to thermal expansion and contraction. The channel oscillates in sync with the strength members, maintaining fiber retention without requiring complex fixed retention mechanisms. This dynamic structure prevents fiber migration while keeping the overall cable design simple.
Solution Approach 2:
The patent modifies the channel geometry parameters, specifically making the channel height variable rather than fixed. The channel height changes in response to thermal conditions, allowing the fiber to be retained effectively without complex retention structures. This parameter change enables simple yet reliable fiber positioning.
3Object-affected harmful factors
If the channel is large enough so that the fiber need not be in contact with any one of the channel walls, then the fiber is protected from contact stresses, but the oscillating configuration allows fiber migration and the cable reduces flexibility
Solution Approach 1:
The patent employs a dynamic oscillating channel that moves in sync with the strength members during thermal cycles. This oscillation maintains the fiber in a protected position without contact stresses while preventing migration. The channel's dynamic motion ensures the fiber remains retained even when the channel is relatively large, balancing protection with retention.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The cable achieves reduced size and weight with equivalent or improved performance compared to standard designs, maintaining allowable fiber working strain under increased loads and temperature deviations, and minimizing fiber migration, thus preventing signal attenuation and stress on the fibers.
Implementation Method 1
Each optical element oscillates within the cavity on a plane of oscillation, the plane of oscillation or oscillation plane being parallel to the plane comprising the longitudinal axis of the cavity and the longitudinal axes of the strength members
Implementation Method 2
They typically comprise an outer jacket surrounding a number of optical fibers and two strength members... capable of withstanding strains by using large strength members with high Young's modulus
Implementation Method 3
accommodating the surplus length of the fiber generally created at low temperatures due to the different coefficient of thermal expansion between the fiber and the jacket
Data Source
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AI summary
It is disclosed a flat optical drop cable comprising an outer sheath forming a cavity, the cavity being shaped in the form of a stadium, at least one strength member, and at least one optical fiber element comprising one or more optical fibers. The at least one optical fiber element oscillates within the cavity on an oscillation plane parallel to a longitudinal plane of the cable, and an height of the cavity substantially corresponds to an height of the at least one optical fiber element.