SZ-Stranded Ribbon Cable With Elastomer Shell for Low-Strain Bending
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Solution Overview
Problem
Existing optical fiber cables with planar ribbons face challenges in achieving high fiber density and flexibility, as they require significant free space for undulating shapes, leading to increased strain and attenuation, and traditional SZ stranding methods lack efficient mechanisms to maintain fiber integrity under bending stresses.
Innovation Solution
The optical fiber cable design incorporates SZ-stranded, tightly buffered ribbon stacks around a central element, secured by a binder film and sheath, with a non-uniform bending axis and minimal core strain, allowing for a high fiber density within a small diameter, and uses an elastic binder film to accommodate external forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If planar ribbons are arranged in a parallel stack with traditional SZ stranding, then fiber density can be increased, but the ribbon stack requires significant free space to accommodate out-of-plane undulating shapes during bending, leading to increased strain and attenuation
Solution Approach 1:
The patent applies a thin, flexible binder film that conforms to the asymmetric cross-section of the ribbon stack. This film provides continuous support during bending, eliminating the need for excessive free space while allowing the ribbons to maintain their lowest energy state. The flexible film adapts to the undulating shape without inducing strain on the fibers.
Solution Approach 2:
The patent changes the geometric parameters of the binder film to match the asymmetric moment of inertia of the planar ribbon stack. By configuring the film's thickness and stiffness parameters to correspond with the ribbon stack's asymmetric geometry, the system achieves high fiber density while minimizing bending-induced strain and attenuation.
2Area of stationary object
If buffer tube area is reduced to increase fiber density, then cable diameter can be reduced, but traditional SZ stranding techniques lack mechanisms to maintain fiber integrity under bending stresses
Solution Approach 1:
The binder film acts as a flexible shell that directly supports the ribbon stack during bending. Unlike traditional loose buffer tubes, this thin film provides continuous mechanical support while conforming to the asymmetric shape of the ribbon stack, maintaining fiber integrity even in reduced-diameter configurations.
Solution Approach 2:
The binder film serves as an intermediary between the ribbon stack and external bending forces. It distributes and absorbs bending stresses, preventing direct transmission of mechanical loads to the fibers, thereby maintaining fiber integrity in compact cable designs.
3Quantity of substance
If asymmetrical planar ribbons are densely packed, then fiber density increases, but the ribbons require free space to achieve their lowest energy state during bending
Solution Approach 1:
The flexible binder film eliminates the need for large free space volumes by providing continuous mechanical support to the asymmetric ribbon stack. The film's ability to conform to the ribbons' lowest energy state during bending allows dense packing without compromising fiber performance.
Solution Approach 2:
The patent addresses the free space requirement by transitioning from a volumetric solution (large buffer tubes) to a surface-based solution (thin binder film). This dimensional change allows the system to maintain fiber integrity through surface support rather than volumetric clearance.
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
The design achieves a high fiber density of up to 864 fibers within a 1-inch duct while minimizing strain and attenuation, ensuring flexibility and durability under bending stresses through the use of a conforming tensioned elastomer shell and strategic core construction.
Implementation Method 1
uses an elastic binder film to accommodate external forces
Implementation Method 2
conforming tensioned elastomer shell
Data Source
AI summary
An optical fiber cable includes a central element, extending along a longitudinal axis of the optical fiber cable, and a plurality of routable subunits, each routable subunit having a rigidly stranded ribbon stack and a tight buffer layer surrounding the ribbon stack, wherein the subunits are SZ-stranded around the central element to form a cable core. A binder film continuously and contiguously surrounds the plurality of routable subunits along the longitudinal axis and a cable sheath continuously and contiguously surrounds the binder film along the longitudinal axis, wherein the cable sheath has an inside surface and an outside surface, the inside surface defining an elliptical shape and the outside surface defining a generally circular shape.