NFC Coil Antenna Integration in Metallic Chassis
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Solution Overview
Problem
Integrating near field communications (NFC) coil antennas into portable devices with full metallic chassis, such as thin laptop computers, is challenging due to the need for a non-metallic surface for radiation, which is not available in these designs.
Innovation Solution
A ring-shaped NFC coil antenna with a center cutout is integrated into the trackpad or keyboard area, utilizing metal-free spaces, and a magnetic field booster is aligned with the coil antenna to improve NFC range. Ferrite material is used to protect the magnetic fields from generating Eddy currents in the metallic chassis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a full metallic chassis is used to maintain mechanical strength in thin design, then device strength and mechanical integrity are improved, but NFC antenna radiation capability deteriorates due to lack of non-metallic surface
Solution Approach 1:
The patent segments the chassis structure by introducing a localized non-metallic region (cutout or insert) within the metallic chassis specifically for NFC antenna placement. This allows the majority of the chassis to remain metallic for structural strength while creating a dedicated zone with appropriate electromagnetic properties for antenna radiation.
Solution Approach 2:
The patent introduces a non-metallic material (such as plastic insert or coated region) as an intermediary between the NFC antenna and the metallic chassis. This intermediary layer prevents direct contact between the antenna and conductive metal surfaces, eliminating Eddy current interference while maintaining the overall metallic chassis structure for mechanical strength.
2Reliability
If a cutout is created in the metallic chassis for NFC antenna integration, then NFC antenna radiation capability is improved, but mechanical strength and structural integrity deteriorate
Solution Approach 1:
The patent employs composite construction by combining metallic materials (for structural strength) with non-metallic materials (for NFC antenna integration) within the chassis. The composite structure allows both metallic and non-metallic regions to coexist, each performing their respective functions optimally without compromising overall device integrity.
3Length of moving object
If the NFC antenna is placed close to the metallic chassis, then device thickness is reduced, but Eddy currents are generated that interfere with magnetic fields
Solution Approach 1:
The patent introduces a non-conductive intermediary material positioned between the NFC antenna and the metallic chassis. This intermediary layer electrically isolates the antenna from the conductive metal surfaces, preventing Eddy current generation while allowing the antenna to remain in close proximity to the chassis for thin device design.
Solution Approach 2:
The patent utilizes thin non-metallic films or coatings applied to the inner surface of the metallic chassis where the NFC antenna is positioned. These thin films provide electrical insulation to prevent Eddy currents while maintaining minimal thickness to preserve device compactness and thin profile.
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 solution allows for effective NFC antenna integration without compromising the functionality of the trackpad or keyboard, enhancing the NFC range by increasing the quality factor of the magnetic field and preventing Eddy currents, thus enabling efficient near field coupling.
Implementation Method 1
a magnetic field booster is aligned with the coil antenna to improve NFC range
Implementation Method 2
The ring shaped coil antenna may include a center cutout in order for the coil antenna to flush into a circuit component of the trackpad or the keyboard area
Implementation Method 3
Ferrite material is used to protect the magnetic fields from generating Eddy currents in the metallic chassis
Implementation Method 4
Ferrite material is used to protect the magnetic fields from generating Eddy currents in the metallic chassis
Data Source
AI summary
Described herein are techniques related to near field coupling and wireless power transfers. In an implementation, a portable device may include full metallic chassis devices. The full metallic chassis devices may include a keyboard and/or trackpad that include a plastic keycap. The plastic keycap may integrate a booster component to increase near field communications (NFC) range of a coil antenna that is integrated onto a surface plane above a circuit board of a switch that is connected to the plastic keycap. In an implementation, a ferrite material is inserted between the coil antenna and the circuit board to protect the coil antenna from Eddy currents that may be induced on a metallic chassis that lie underneath the circuit board.