Compound-Curved Antenna Substrates Without Wrinkling
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Solution Overview
Problem
Existing electronic devices with complex shapes, such as head-mounted devices, face challenges in integrating antennas with compound curvature without causing wrinkles or distortions during the shaping process.
Innovation Solution
A three-dimensional flexible printed circuit contouring tool is used to transform a planar sheet of flexible printed circuit material into an antenna with compound curvature, preventing wrinkling by controlling lateral flow during the shaping process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a planar flexible printed circuit is transformed into a three-dimensional shape with compound curvature, then the antenna can be integrated into complex device shapes, but wrinkling occurs during the forming process
Solution Approach 1:
The patent applies preliminary action by pre-forming the flexible printed circuit substrate into a three-dimensional shape with compound curvature before installing the antenna. The contouring tool is used to transform the planar substrate into the desired shape in advance, ensuring proper integration into complex device shapes while preventing wrinkles from forming during the forming process
Solution Approach 2:
The patent uses a contouring tool as an intermediary device to transform the planar flexible printed circuit substrate into a three-dimensional shape. This intermediary tool enables the transformation process while controlling the forming conditions to prevent wrinkling, acting as a mediator between the planar substrate and the complex three-dimensional configuration
2Shape
If the flexible printed circuit is formed into compound curvature, then the antenna matches the housing shape, but stress concentrates in the metal trace
Solution Approach 1:
The patent applies local quality by positioning the metal trace at the neutral stress plane of the flexible printed circuit substrate. This ensures that the metal trace is located at the specific position where stress is minimized during bending, while other regions of the substrate accommodate the compound curvature. The neutral stress plane positioning creates different stress distributions at different locations within the substrate structure
Solution Approach 2:
The patent resolves stress concentration by transitioning from a two-dimensional planar configuration to a three-dimensional structure with the metal trace positioned at the neutral stress plane. This dimensional consideration allows the metal trace to be located at a specific depth within the substrate where bending stresses are minimized, rather than being constrained to the surface
3Ease of operation
If the planar substrate is bent into three-dimensional shape, then the antenna conforms to the device, but wrinkles form on the substrate surface
Solution Approach 1:
The patent applies preliminary action by using a contouring tool to pre-form the flexible printed circuit substrate into its final three-dimensional shape before antenna installation. This preliminary forming process ensures that the substrate achieves the desired compound curvature while maintaining surface smoothness and preventing wrinkles from forming during subsequent handling or installation
Data Source
AI summary
A head-mounted device may have a head-mounted housing that is configured to be worn on a head of a user. While the head-mounted device is being worn, optical modules in the head-mounted device may provide images to eye boxes located rearward of the head-mounted device. A forward-facing display on a front portion of the head-mounted device may be covered with a transparent housing portion forming a display cover layer. An antenna may be mounted in the device. A curved portion of the display cover layer or other dielectric housing layer may overlap the antenna. The antenna and/or other components may be formed by contouring a flexible printed circuit into a shape characterized by a surface with compound curvature. The contoured flexible printed circuit may have polymer layers and a metal trace between the polymer layers. A neutral stress plane may be aligned with the metal trace.