Optical Fiber Cable Waterproofing via Water-Absorbent Fibers
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Solution Overview
Problem
Existing optical fiber cables struggle to maintain a high density of optical fibers while ensuring waterproof properties, which is crucial for preventing moisture-induced deterioration of transmission characteristics.
Innovation Solution
The optical fiber cable and unit incorporate a configuration of multiple optical fibers and water-absorbent fibers within a sheath or coating portion, where the ratio of water-absorbent fiber areas to the accommodating portion is between 1% and 5%, and the maximum gap area surrounding the optical fibers is 1.0 mm² or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If optical fibers are densely packed to increase capacity, then the number of optical fibers increases, but gap portions remain large allowing water penetration
Solution Approach 1:
The patent applies local quality by placing water-absorbent fibers specifically in gap portions between optical fiber bundles. The water-absorbent fibers are not uniformly distributed but are strategically positioned in locations where gaps exceed a predetermined area, creating localized waterproofing exactly where needed while maintaining high optical fiber density elsewhere.
Solution Approach 2:
The water-absorbent fibers act as an intermediary substance between the optical fiber bundles and the external environment. These fibers absorb water that penetrates through the sheath, preventing water from reaching and damaging the optical fibers. The intermediary layer of water-absorbent material bridges the gap between the protective sheath and the sensitive optical fibers.
2Reliability
If water-absorbent material is added to improve waterproofing, then waterproof property improves, but the space for optical fibers decreases
Solution Approach 1:
The water-absorbent fibers are placed only in specific gap portions between optical fiber bundles rather than being uniformly distributed throughout the entire cable cross-section. This localized placement ensures waterproofing is provided exactly where gaps exist without unnecessarily reducing the overall space available for optical fibers.
Solution Approach 2:
The water-absorbent fibers are porous materials that can absorb water through capillary action. Their porous structure allows them to effectively capture and retain water molecules that penetrate the sheath, converting the harmful water intrusion into absorbed water held within the porous structure of the fibers, thus protecting the optical fibers.
3Reliability
If gap portions are reduced to prevent water penetration, then waterproof property improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent extracts the waterproofing function from the main bundle structure and applies it separately to specific gap portions. Instead of requiring precise control of all gaps between optical fibers, the solution identifies and treats only those gap portions that exceed a predetermined area threshold, extracting and addressing the problematic areas individually.
Solution Approach 2:
The patent introduces a parameter threshold (predetermined area) for identifying which gap portions require water-absorbent fibers. By changing the criterion from controlling all gaps to controlling only gaps exceeding a specific area, the manufacturing precision requirement is relaxed while maintaining effective waterproofing where it is most needed.
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
This configuration allows for high-density mounting of optical fibers while significantly improving waterproof properties, thereby preventing water ingress and maintaining optimal transmission characteristics.
Implementation Method 1
a plurality of water-absorbent fibers; and a sheath covering a periphery of the plurality of optical fibers and the plurality of water-absorbent fibers
Data Source
AI summary
An optical fiber cable includes a plurality of optical fibers, a plurality of water-absorbent fibers, and a sheath covering a periphery of the plurality of optical fibers and the plurality of water-absorbent fibers. A ratio of areas of the water-absorbent fibers to an area of an accommodating portion in an inner side of the sheath in a cross section orthogonal to a longitudinal direction of the optical fiber cable is 1% or more and 5% or less, and a maximum value of an area of a gap portion surrounded by the optical fibers in the cross section is 1.0 mm2 or less.