Folded Sheet Metal Antenna for Compact HMD EMI Control
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Solution Overview
Problem
It is challenging to incorporate antennas with satisfactory wireless performance into compact and lightweight head-mounted displays due to the presence of conductive structures that can detune antenna performance and introduce noise or interference.
Innovation Solution
The use of a folded sheet metal antenna design, where the antenna resonating element and ground are formed from separate portions of a sheet metal member, with a third portion coupling them and producing a spring force to maintain parallelism with the cover, helps mitigate electromagnetic interference and optimize wireless performance while reducing manufacturing costs and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If antennas are incorporated into head-mounted displays, then wireless communication capability is achieved, but antenna performance deteriorates due to detuning from conductive structures and electromagnetic interference
Solution Approach 1:
The antenna system is segmented into distinct functional portions: a resonating element portion (first portion) and a ground portion (second portion), separated by a cavity. This segmentation isolates the resonating element from interfering conductive structures while maintaining necessary electrical connections through the folded third portion, thereby reducing electromagnetic interference and detuning effects.
Solution Approach 2:
The antenna structure is nested within the head-mounted display housing, with the resonating element portion positioned against the cover and the ground portion mounted to the logic board or housing. The folded third portion nests around the cavity, creating a compact integrated structure that minimizes space while maintaining antenna performance and reducing interference from external conductive elements.
2Weight of moving object
If compact and lightweight design is implemented, then device portability is improved, but antenna performance deteriorates due to limited space for antenna structures
Solution Approach 1:
The antenna structure is merged with existing structural components of the head-mounted display. The resonating element is formed from a portion of the sheet metal cover or housing, and the ground portion is integrated with the logic board ground plane or housing chassis. This merging eliminates the need for separate antenna components, reducing overall device weight while maintaining adequate antenna performance through strategic positioning and configuration.
Solution Approach 2:
The sheet metal cover and housing serve multiple functions: they provide structural support for the device, form the resonating element of the antenna, and act as a mounting surface for the antenna ground. This multi-functionality reduces the number of separate components needed, thereby reducing device weight and complexity while maintaining antenna functionality.
3Ease of manufacture
If traditional antenna implementations are used, then manufacturing is simpler, but device weight and volume increase
Solution Approach 1:
The antenna structure is merged with existing structural components of the head-mounted display. The resonating element is formed from a portion of the sheet metal cover or housing, and the ground portion is integrated with the logic board ground plane or housing chassis. This merging eliminates the need for separate antenna components, reducing overall device weight while maintaining adequate antenna performance through strategic positioning and configuration.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design enhances wireless performance by maintaining antenna parallelism and efficiency, reduces manufacturing complexity and weight, and minimizes the impact of conductive components on antenna performance, allowing for a compact and effective wireless solution in head-mounted devices.
Implementation Method 1
The third portion of the sheet metal member may couple the first portion to the second portion and may be folded around the cavity. The third portion may produce a spring force that presses the first portion against the cover.
Data Source
AI summary
An electronic device may have first and second rear-facing displays, a front-facing display, a cover at a front side overlapping the front-facing display, and an antenna that radiates through the cover. The antenna may be formed from sheet metal. The antenna may have a resonating element formed from a first portion of the sheet metal and an antenna ground that includes a second portion of the sheet metal separated from the first portion by a cavity. A third portion of the sheet metal may couple the first portion to the second portion and may be folded around the cavity to produce a spring force that presses the first portion against the cover. The first portion and the cover may have the same compound curvature. The second portion may form a conductive cavity for the antenna.