Optical Fiber Cable Recess Waterproofing via Absorption Member

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Solution Overview

Problem

Existing optical fiber cables face issues with water ingress and leakage due to water traveling along recesses between adjacent optical fibers, which compromises their waterproofness.

Innovation Solution

The optical fiber cables and units incorporate optical fiber ribbons with connecting resins having recesses and water absorption members with thicknesses smaller than the center-to-center distance between adjacent fibers, allowing the absorption members to easily enter these recesses and prevent water leakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the connecting resin has recesses between adjacent optical fibers to facilitate separation and installation, then ease of operation is improved, but water can travel along the recesses causing water ingress and compromising waterproofness

Engineering Contradiction:
Improveease of separation and installationVSAvoidwater ingress
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

A water absorption member is introduced as an intermediary component between the optical fiber ribbon and the external environment. This member selectively absorbs water that attempts to enter through the recesses in the connecting resin, preventing water ingress while preserving the recesses' original function for ease of separation and installation.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The water absorption member converts the harmful effect of water traveling along recesses into a beneficial process. Instead of allowing water to cause damage, the absorption member utilizes the water flow through the recesses to activate water absorption, transforming the potential harm into a protective mechanism.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

2Reliability

If water absorption members are made thick to effectively block water, then waterproofness is improved, but they cannot easily enter the recesses between adjacent optical fibers

Engineering Contradiction:
ImprovewaterproofnessVSAvoidease of entry into recesses
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The thickness parameter of the water absorption member is precisely controlled to be less than the center-to-center distance between adjacent optical fibers. This parameter change enables the absorption member to easily enter the recesses while maintaining sufficient water absorption capability to block water ingress effectively.

Inventive Principle:
Principle #35Parameter changes

3Ease of manufacture

If conventional waterproofing materials are used without considering the recess structure, then manufacturing simplicity is maintained, but water leakage occurs along the recesses reducing reliability

Engineering Contradiction:
Improvemanufacturing simplicityVSAvoidwaterproofness
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The water absorption member is positioned specifically at the recess locations between adjacent optical fibers, where water ingress is most likely to occur. This localized approach provides enhanced waterproofness at critical points without requiring complex modifications to the entire cable structure, maintaining manufacturing simplicity while improving reliability.

Inventive Principle:
Principle #3Local quality

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 enhances the waterproofness of the optical fiber cables and units by allowing water absorption members to effectively block water ingress and leakage, even in intermittent coupling type ribbons, thereby improving handling and reducing manufacturing costs.

Implementation Method 1

Water that has entered the cable may travel in the longitudinal direction along the connecting resin. In particular, when the optical fiber ribbon has a recess between the adjacent optical fibers, water may travel a longer distance along the recess.

Methodology Applied
Scientific EffectCapillary action: Capillary Action

Data Source

PatentEP4664173A1Optical fiber cable and optical fiber unit
Publication Date: 2025.12.17 SUMITOMO ELECTRIC INDUSTRIES LTD
  • EP4664173A1 patent drawingFigure 1
  • EP4664173A1 patent drawingFigure 2
  • EP4664173A1 patent drawingFigure 3

AI summary

This optical fiber cable comprises, a plurality of optical fiber ribbons, a plurality of water absorbing members, and an outer covering that covers the periphery of the plurality of optical fiber ribbons and the plurality of water absorbing members. The optical fiber ribbons each have a plurality of optical fiber cores, and a connecting resin that connects together the plurality of optical fiber cores arranged in parallel in a direction orthogonal to the longitudinal direction of the plurality of optical fiber cores. The connecting resin has at least one recess between the adjacent optical fiber cores, and the thickness of each water absorbing member is less than the center-to-center distance of two adjacent optical fiber cores in the parallel arrangement direction of the optical fiber cores.