Flat Flexible Cable Segmentation for Compact USB 2.0 Design
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Solution Overview
Problem
Conventional flat flexible cables (FFC) designed for USB 2.0 applications require larger cable widths and thicknesses due to higher current demands and data transmission rates, posing a challenge in compact designs like airline seat back devices where space is limited.
Innovation Solution
A flat flexible cable with spaced power and data transmission wires embedded in a non-conductive polymeric matrix, featuring a shielded middle region and non-shielded end regions, allowing for efficient data and power transmission while maintaining a compact profile, integrated with a retractable cord reel mechanism that prevents cord pinching or wedging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional FFC is designed to meet USB 2.0 standards for higher currents and data transmission rates, then data transmission capability is improved, but cable width and thickness increase
Solution Approach 1:
The cable is segmented into distinct functional regions: a first region with data transmission wires, a second region with power transmission wires, and a third region with both types of wires. This segmentation allows optimized wire configuration for each function while maintaining compact overall dimensions.
Solution Approach 2:
The patent transitions from conventional round cable geometry to a flat flexible cable structure, utilizing the width dimension more efficiently. By arranging wires in parallel rows within a flat profile, the cable achieves USB 2.0 performance without proportionally increasing cross-sectional area.
2Power
If conventional FFC is designed to meet USB 2.0 standards for higher currents and data transmission rates, then power transmission capability is improved, but cable thickness increases
Solution Approach 1:
Different regions of the cable have different wire configurations optimized for their specific functions. The second region contains multiple power transmission wires with larger cross-sections localized where high current capacity is needed, while the first region maintains thinner data wires where high power transmission is not required.
Solution Approach 2:
The patent varies wire gauge, spacing, and material composition across different regions of the cable. Power transmission wires have larger cross-sectional areas and different spacing compared to data wires, optimizing electrical parameters for each function while controlling overall cable thickness.
3Reliability
If shielding is added to protect data transmission wires, then signal quality is improved, but cable complexity increases
Solution Approach 1:
The shielding layer is integrated with the polymeric matrix to form a unified protective structure. The metal-containing shielding layer is deposited directly onto the matrix, creating a combined electromagnetic shield and structural component rather than separate shielding elements.
Solution Approach 2:
The polymeric matrix serves as an intermediary between the data transmission wires and the external environment, providing both mechanical support and electromagnetic isolation. The matrix mediates the interaction between wires and shielding, simplifying the overall structure.
Data Source
AI summary
A cord reel assembly described herein comprises a cord reel including a flat flexible cable that comprises a ribbon of generally parallel power transmission and data transmission wires embedded in a non-conductive polymeric matrix. Each data transmission wire is spaced and insulated from any adjacent wire by the polymeric matrix. The power transmission wires are flattened relative to the data transmission wires, and have a larger gauge than the data transmission wires. The FFC comprises non-shielded end regions flanking a shielded middle region that includes a shielding layer on at least one side of the cable, and a non-conductive coating covers the shielding layer.