Dual Layer Micro Optical Fiber Cable Design

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Solution Overview

Problem

Existing micro optical fiber cables have large diameters and high weights, making them unsuitable for smooth blowing operations and installation in micro ducts, leading to poor performance in cable blowing machines.

Innovation Solution

A dual-layer micro optical fiber cable design with a central strength member, helically stranded first and second layers of buffer tubes filled with gel, and outer layers of binder yarns and a jacket, providing reduced diameter, weight, and enhanced crush resistance, allowing easier installation in micro ducts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the diameter of buffer tubes is reduced to decrease cable diameter and weight, then blowing performance improves, but crush resistance deteriorates

Engineering Contradiction:
Improvecable diameterVSAvoidcrush resistance
Core Design Contradiction:
Volume of moving objectVSStrength

Solution Approach 1:

The buffer tube wall is segmented into two distinct layers: an inner layer made of high-density polyethylene (HDPE) providing crush resistance, and an outer layer made of low-density polyethylene (LDPE) providing flexibility and ease of blowing. This segmentation allows each layer to optimize for its specific function while working together to achieve overall performance.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The buffer tube is constructed using composite materials - specifically a combination of HDPE and LDPE with different thicknesses (inner layer 30-70 microns HDPE, outer layer 20-50 microns LDPE). This composite structure enables the buffer tube to simultaneously achieve reduced diameter, improved blowing performance, and maintained crush resistance through the synergistic properties of the two materials.

Inventive Principle:
Principle #40Composite materials

2Weight of moving object

If the weight of the cable is reduced to improve blowing performance, then installation in micro ducts becomes easier, but structural strength deteriorates

Engineering Contradiction:
Improvecable weightVSAvoidtensile strength
Core Design Contradiction:
Weight of moving objectVSStrength

Solution Approach 1:

Different components of the cable are assigned different material qualities and thicknesses optimized for their specific functions: the central strength member uses high-tensile materials (FRC/GRP) for maximum strength-to-weight ratio, the buffer tubes use thin-walled composite structure for lightness with adequate protection, and the outer sheath provides environmental protection. This local optimization of material properties achieves overall weight reduction while maintaining necessary strength characteristics.

Inventive Principle:
Principle #3Local quality

Data Source

PatentEP3663822B1Dual layer micro optical fiber cable
Publication Date: 2023.03.01 STERLITE TECHNOLOGIES LTD
  • EP3663822B1 patent drawingFigure 1

AI summary

The present disclosure provides an optical fiber cable (100). The optical fiber cable (100) includes a first layer (108) and a second layer (110). The second layer (110) surrounds the first layer (108). The first layer (108) includes a first plurality of buffer tubes (122). The second layer (110) comprises a second plurality of buffer tubes (124). Each buffer tube of the first plurality of buffer tubes (122) and the second plurality of buffer tubes (124) has a thickness of at most 0.15 millimeter. Each buffer tube of the first plurality of buffer tubes (122) and the second plurality of buffer tubes (124) includes a first material layer (126) and a second material layer (128). The second material layer (128) surrounds the first material layer (126). The first material layer (126) is made of polybutylene terephthalate. The second material layer (128) is made of polycarbonate.