Eyewear Hinge Ribbon Circuit Layout for Bend-Strain Reliability
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Solution Overview
Problem
Electronic eyewear devices face issues with increased strain, degradation, and potential failure of electrical pathways due to repetitive bending at hinges, as well as contamination risks at hinge locations.
Innovation Solution
The implementation of a flexible ribbon circuit that spirals around the hinge core, providing highly parallelized electrical pathways to distribute strain and reduce localized degradation, while also incorporating a hinge force mechanism to manage rotational forces and protect against contaminants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional electrical pathway is used at the hinge, then the device structure is simple, but the electrical pathway experiences increased strain and degradation due to repetitive bending
Solution Approach 1:
The electrical pathway is configured in a spiral shape around the hinge core, transforming the straight linear pathway into a curved configuration. This curvature allows the electrical pathway to accommodate the rotational movement of the hinge without experiencing sharp bending stresses, thereby reducing strain and degradation while maintaining connection between the frame and temple portion.
Solution Approach 2:
The electrical pathway extends in the radial dimension by spiraling around the hinge core rather than following a simple linear path. This dimensional extension distributes the mechanical stress of hinge rotation along a longer, more gradual path, reducing localized strain at any single point while maintaining electrical connectivity.
2Ease of operation
If the hinge is left open for accessibility, then ease of operation is improved, but contamination risks increase
Solution Approach 1:
A flexible cover assembly is implemented that can dynamically open and close over the hinge area. When not in use, the cover closes to protect the hinge from contaminants such as dust and moisture. When operation is needed, the cover can be opened to provide access, thus balancing protection with ease of operation.
Solution Approach 2:
The cover assembly is designed to be movable rather than fixed, allowing it to transition between open and closed states. This dynamic capability enables the system to adapt to different operational requirements, providing contamination protection when the hinge is not in use while allowing easy access when needed.
3Ease of manufacture
If a straight electrical pathway is used, then manufacturing is simpler, but localized degradation occurs at the hinge bend
Solution Approach 1:
The electrical pathway is formed in a spiral configuration around the hinge core, distributing the bending stress across multiple gradual curves rather than concentrating it at a single sharp bend. This curved geometry reduces localized degradation while still allowing for manufacturing using standard flexible circuit board techniques.
Solution Approach 2:
The electrical pathway is effectively segmented into multiple small bends along the spiral path rather than one large bend at the hinge. This segmentation distributes the mechanical stress across many smaller, less severe curvature changes, reducing the risk of failure at any single point while maintaining overall connectivity.
Data Source
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AI summary
An electronic eyewear device includes a frame having a first electronic subsystem that includes a near-eye graphical display, a temple portion having a second electronic subsystem, and a hinge assembly rotatably coupling the frame to the temple portion. According to an example, the hinge assembly includes a hinge core defining a hinge axis, a cover that spans a gap between the frame and the temple portion on at least one side of the hinge axis, and a flexible ribbon circuit electrically coupling the first electronic subsystem to the second electronic subsystem. In at least some examples, the flexible ribbon circuit spirals around the hinge core between the cover and the hinge core.