Rugged Fiber Optic Cable Design for High Density and Crush Resistance
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Solution Overview
Problem
Fiber optic cables face challenges in achieving high fiber density while providing adequate protection against crush, impact, and moisture exposure, particularly in outdoor applications, and they often have large diameters and higher costs due to individual fiber buffering, and are not well-suited for direct termination to multi-fiber connectors.
Innovation Solution
The development of a fiber optic cable design featuring optical fiber units with a tight or semi-tight polymer coating and a thermoplastic buffer applied directly over the outer coating, combined with an aramid yarn layer that can include water-blocking elements, allowing for high fiber density, resistance to crush and impact, and moisture protection, while enabling easy termination and compact construction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tight buffer cables are used to provide protection from moisture exposure and crush forces, then cable protection is improved, but cable diameter increases and fiber density decreases
Solution Approach 1:
The patent merges the functions of individual fiber buffering and collective cable protection by applying a single thermoplastic tight buffer coating over multiple optical fibers (typically 12-24 fibers) bundled together. This eliminates the need for separate individual fiber buffers while maintaining protection against crush and impact forces, thereby reducing cable diameter and increasing fiber density while preserving mechanical protection.
Solution Approach 2:
The thermoplastic tight buffer coating serves multiple functions simultaneously: it provides individual fiber protection, collective cable protection against crush and impact, moisture barrier, and structural integrity. This multi-functional approach replaces multiple separate protective layers, reducing overall cable diameter while maintaining comprehensive protection.
2Quantity of substance
If loose tube cables are used to achieve high fiber density, then fiber density is improved, but resistance to crush and impact forces decreases
Solution Approach 1:
The patent combines the high-density advantage of loose tube construction with the mechanical strength of tight buffer construction by bundling multiple fibers in a compact arrangement and then applying a thermoplastic tight buffer coating that provides crush and impact resistance. This hybrid approach achieves both high fiber density and mechanical strength.
Solution Approach 2:
The patent uses composite material structures combining the fiber bundle core with a thermoplastic buffer coating layer that has enhanced mechanical properties. This composite construction provides both the compactness needed for high density and the strength needed for crush and impact resistance.
3Reliability
If individual fiber buffering is applied to provide protection, then fiber protection is improved, but cable diameter increases and manufacturing cost increases
Solution Approach 1:
The patent merges multiple individual fiber buffering operations into a single tight buffer coating process that protects multiple fibers simultaneously. This reduces manufacturing steps, material usage, and labor costs while maintaining comprehensive fiber protection. The single coating process is more efficient and cost-effective than applying individual buffers to each fiber.
Solution Approach 2:
Instead of creating unique protective structures for each fiber, the patent uses a standardized tight buffer coating process that can be uniformly applied to bundles of fibers. This standardization reduces manufacturing complexity and cost while providing consistent protection across all fibers in the cable.
4Volume of moving object
If fiber ribbons are used to achieve compact construction, then cable compactness is improved, but adaptability to sharp bends decreases due to preferential bend axis
Solution Approach 1:
The patent uses a dynamic fiber bundle structure where individual fibers can move independently within the tight buffer coating, unlike rigid fiber ribbons with fixed orientations. This allows the cable to adapt to various bend directions and sharp bends without the preferential bend axis limitation, while maintaining compactness through the tight buffer construction.
Data Source
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AI summary
An optical fiber cable having a plurality (12) of optical fiber members (14). Each optical fiber member (14) includes an optical fiber (16) and a protective coating (18) surrounding the optical fiber (16). A polymer coating (20) surrounds the plurality (12) of optical fiber members (14) and a portion of the polymer coating (20) is located between at least some of the optical fiber members (14). The optical fiber members (14) and the polymer coating (20) form an optical fiber unit (10). A tight buffer (22) surrounds the optical fiber unit (10).