Flexible Cable Shielding for High-Frequency Signal Integrity
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Solution Overview
Problem
Conventional flexible cables experience significant deterioration in transmission characteristics at high frequency bands due to the proximity of shield members to signal wires, leading to inaccurate signal reception and electromagnetic noise radiation issues.
Innovation Solution
A flexible cable design where high-frequency signal wires are not covered with a shield member, while electromagnetic noise source wires are covered, ensuring transmission characteristics and suppressing noise radiation, with additional timing adjustment mechanisms to synchronize signal arrival at ICs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a shield member covers the signal wire to suppress electromagnetic noises, then electromagnetic noise suppression is improved, but transmission characteristic deteriorates in high frequency band
Solution Approach 1:
The patent applies different shielding configurations to different wire groups based on their function: the first conductive wire group (carrying clock signals or other electromagnetic noise signals) is covered by the shield member to suppress noise radiation, while the second conductive wire group (carrying high-frequency differential signals) is not covered to maintain transmission characteristics. This local differentiation resolves the contradiction by applying shielding only where it is beneficial.
2Object-affected harmful factors
If the shield member is placed close to the signal wire to suppress electromagnetic noises, then electromagnetic noise suppression is improved, but transmission characteristic deteriorates due to short distance
Solution Approach 1:
The patent differentiates between two types of conductive wires and applies shielding selectively: clock signal wires (which are electromagnetic noise sources) are positioned close to the shield member for effective noise suppression, while high-frequency differential signal wires are positioned away from the shield member to avoid transmission characteristic deterioration. This spatial differentiation based on wire function resolves the contradiction.
3Object-affected harmful factors
If all signal wires are covered with shield member to suppress electromagnetic noises, then electromagnetic noise suppression is improved, but transmission characteristic of high frequency signals deteriorates
Solution Approach 1:
The patent implements selective shielding where only the first conductive wire group (clock signals or electromagnetic noise sources) is covered by the shield member, while the second conductive wire group (high-frequency differential signals) remains uncovered. This localized approach ensures electromagnetic noise suppression for noise-generating wires while preserving transmission characteristics for high-frequency signal wires.
Solution Approach 2:
The patent divides the conductive wires into two distinct groups: the first conductive wire group for clock signals or other electromagnetic noise signals, and the second conductive wire group for high-frequency differential signals. By segmenting the wire groups and applying different shielding treatments to each group, the patent resolves the contradiction between noise suppression and transmission characteristic maintenance.
4Measurement precision
If timing adjustment mechanism is added to synchronize signal arrival, then signal reception accuracy is improved, but device complexity increases
Solution Approach 1:
The patent incorporates a timing adjustment mechanism that pre-adjusts the timing of signals before they reach the IC. By performing the timing adjustment in advance (preliminarily), the mechanism compensates for timing deviations caused by different transmission paths, ensuring accurate signal reception without requiring complex real-time adjustment systems.
Data Source
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AI summary
A flexible cable is provided in which a transmission characteristic can be ensured in a high frequency band, and electromagnetic noises can be suppressed. A flexible cable 11 includes a sheet-like base member (dielectric substance) 1; an adhesive (dielectric substance) 2 which bonds the base member 1 to a cover member (dielectric substance) 3; a shield member 4 which covers the cover member 3 and is bonded or printed to the cover member 3 to suppress electromagnetic noises to be radiated; and a top coating member 5 which covers the shield member 4 to protect the shield member 4. The flexible cable 11 has a differential signal wire group 7 including differential signal wires 6 through which differential signals pass and guard ground wires 9a which prevent the interference from other differential signals; a low-speed signal wire 8 through which a low-speed signal passes; a ground wire 9 used as a ground; and a shield ground wire 10 which is adapted to allow the electric potential of the shield member 4 to be identical to the electric potential of the ground, all of which are provided in the adhesive 2. The differential signal wires 6 are not covered with the shield member 4.