Tight-buffered optical fiber with low-strength polymer coating

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Solution Overview

Problem

Optical fibers in indoor installations face challenges with mechanical stress during extraction and require a balance between protection and ease of stripping, as traditional tight buffers are difficult to strip without tools and loose buffers offer inadequate protection against fiber microbending.

Innovation Solution

A tight buffer layer with specific polymeric material properties, including a combination of buffer-to-fiber clearance and mechanical strength, allowing for easy stripping by hand and maintaining congruence with the optical fiber, is applied to the optical fiber, ensuring protection during installation and use.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a traditional tight buffer is used to protect optical fibers during extraction, then mechanical protection is improved, but ease of stripping deteriorates as the buffer becomes difficult to strip without tools

Engineering Contradiction:
Improvemechanical protectionVSAvoidease of stripping
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent changes the physical and chemical parameters of the buffer material by using a thermoplastic polymer with specific properties (melting point 40-80°C, tensile strength 10-50 MPa, elongation 100-500%) instead of traditional thermosetting materials. This allows the buffer to be easily stripped by heating above its melting point while maintaining mechanical protection during normal use.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent utilizes phase transition of the thermoplastic buffer material from solid to liquid state through heating. The buffer is designed to melt at relatively low temperatures (40-80°C), allowing installers to strip the buffer by applying heat, which softens and liquefies the material for easy removal without damaging the optical fiber.

Inventive Principle:
Principle #36Phase transitions

2Ease of operation

If a loose buffer is used to facilitate easy stripping, then ease of stripping is improved, but mechanical protection deteriorates as the buffer cannot adequately protect against fiber microbending

Engineering Contradiction:
Improveease of strippingVSAvoidprotection against microbending
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent specifies precise parameter ranges for the buffer material: tensile strength between 10-50 MPa and elongation between 100-500%. These parameters ensure the buffer has sufficient mechanical strength to protect against microbending while remaining flexible enough to be easily stripped when heated, resolving the contradiction between protection and ease of removal.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If the buffer layer is made tight to maintain fiber congruence, then fiber protection is improved, but ease of stripping deteriorates requiring special tools and skilled installers

Engineering Contradiction:
Improvefiber congruenceVSAvoidease of stripping
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The patent employs phase transition through controlled heating to strip the tight buffer. By heating the buffer above its melting point (40-80°C), the material transitions from a rigid solid that maintains fiber congruence to a soft, pliable state that can be easily removed by hand, eliminating the need for special stripping tools.

Inventive Principle:
Principle #36Phase transitions

Solution Approach 2:

The patent introduces heat as an intermediary factor to facilitate buffer stripping. Heat acts as a mediator that temporarily alters the buffer material's physical state, enabling easy removal without requiring mechanical stripping tools or specialized skills, while maintaining tight congruence during normal operation.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentEP2183631B1Telecommunication cable equipped with tight-buffered optical fibers
Publication Date: 2018.11.14 PRYSMIAN SPA
  • EP2183631B1 patent drawingFigure 1~2
  • EP2183631B1 patent drawingFigure 3
  • EP2183631B1 patent drawingFigure 4~5

AI summary

The present invention relates to a telecommunication cable equipped with at least one optical fiber coated by a tight buffer layer made from a polymeric material having an ultimate elongation equal to or lower than 100% and an ultimate tensile strength equal to or lower than 10 MPa. The above combination of features of the polymeric material forming the buffer layer allows to obtain an optical fiber which is effectively protected during the installation operations and during use, and at the same time can be easily stripped by the installer without using any stripping tools, simply by applying a small pressure with his fingertips and a moderate tearing force along the fiber axis.