Flexible Board Shielding for Wearable Display Signal Integrity
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Solution Overview
Problem
Wearable display devices with harness cable structures face challenges in downsizing due to thick and heavy cables, and require effective countermeasures against noise interference as data transmission speeds increase.
Innovation Solution
The use of flexible boards with overlapping shielding configurations to transmit signals between display devices, reducing cable thickness and effectively shielding high-speed signal lines to mitigate noise interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a harness cable structure is used for signal transmission, then signal transmission between display devices is achieved, but the cable becomes thick and heavy, preventing downsizing of the wearable display device
Solution Approach 1:
The cable is segmented into multiple independent flexible boards, each carrying specific signal lines. This segmentation allows each board to be optimized for specific functions (power, ground, signal) while maintaining overall transmission reliability. The flexible boards are arranged in layers with shielding between them, enabling thin profile while preserving signal integrity.
Solution Approach 2:
Multiple flexible boards are nested within each other in a layered structure, with inner boards containing signal lines and outer boards providing shielding and power/ground connections. This nested arrangement achieves compact cable thickness while maintaining reliable signal transmission through controlled impedance and shielding.
2Productivity
If data transmission amount and processing speed are increased, then image quality and refresh rate are improved, but noise interference from external sources increases
Solution Approach 1:
Shielding layers are introduced as intermediary elements between signal lines and external noise sources. These shielding layers, positioned adjacent to high-speed signal lines on the flexible boards, act as mediators that redirect electromagnetic interference to ground, protecting sensitive high-speed data transmission from noise contamination.
Solution Approach 2:
Different regions of the flexible board structure are assigned different shielding qualities based on local noise susceptibility. High-speed signal lines receive enhanced local shielding with lower impedance ground connections, while less sensitive power lines have different shielding arrangements. This localized quality optimization enables high data transmission speeds in critical areas without compromising overall cable thickness.
3Shape
If traditional cable structures are used, then ease of manufacture is maintained, but the device cannot achieve thin profile required for wearable applications
Solution Approach 1:
Traditional rigid cable structures are replaced with flexible printed circuit board technology, utilizing thin flexible substrates with conductive traces. This approach achieves minimal cable thickness suitable for wearable devices while maintaining manufacturability through standard FPC fabrication processes including layer lamination, conductive paste application, and automated assembly techniques.
Data Source
AI summary
A wearable display device includes a first display device and a second display device configured to display images correspondingly to left and right eyes, a first flexible board extending from the first display device to the second display device and configured to transmit a signal, and a second flexible board disposed overlapping the first flexible board. The first flexible board includes a surface overlapping the second flexible board and an opposite surface from the surface overlapping the second flexible board, the opposite surface being shielded, and the second flexible board includes a surface overlapping the first flexible board and an opposite surface from the surface overlapping the first flexible board, the opposite surface being shielded.