Meandering Capacitive Electrodes for Wireless Stylus Charging
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Solution Overview
Problem
Existing wireless charging systems face challenges in efficiently transferring power from a wireless power transmitting device to a receiving device due to limitations in capacitive coupling efficiency, which affects the overall charging efficiency and alignment requirements.
Innovation Solution
The implementation of a wireless power transmitting device with a wireless power transmitting capacitor electrode and a receiving device featuring a meandering conductive trace on a dielectric substrate, optimized for near-field capacitive coupling, allowing for efficient power transfer through a capacitive coupling mechanism that maximizes the perimeter of the electrodes for improved alignment tolerance and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional wireless charging system is used, then power can be transmitted wirelessly, but the capacitive coupling efficiency is insufficient and alignment requirements are strict
Solution Approach 1:
The patent applies meandering conductive traces instead of straight lines, creating a curved/path-following geometry that increases the effective perimeter of the capacitor electrode. This meandering pattern allows the electrode to maintain capacitive coupling over larger areas, reducing the strictness of alignment requirements between transmitting and receiving devices while improving overall coupling efficiency.
Solution Approach 2:
The patent transitions from simple planar electrode designs to meandering traces that utilize two-dimensional space more effectively. By extending the trace path in a meandering pattern across the substrate, the design increases the effective area and perimeter of the electrode without increasing the overall footprint, thereby improving capacitive coupling efficiency while maintaining compact form factor.
2Productivity
If the perimeter of capacitor electrodes is increased to improve coupling efficiency, then the charging efficiency improves, but the device area increases
Solution Approach 1:
The meandering conductive trace design allows the electrode perimeter to be significantly increased within the same bounding box area. By following a curved, meandering path instead of a straight line, the electrode achieves greater effective length and perimeter without expanding the overall device footprint, thus improving charging efficiency while maintaining compact dimensions.
Solution Approach 2:
The patent utilizes two-dimensional trace routing to maximize the effective perimeter within a constrained area. The meandering pattern distributes the conductive path across the available substrate area, effectively packing more electrode perimeter into a smaller footprint compared to straight-line configurations, thereby achieving high charging efficiency without increasing device area.
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 enhances the capacitive coupling efficiency between the transmitting and receiving electrodes, ensuring high charging efficiency and rotational invariance, allowing for reliable and efficient wireless charging with improved alignment tolerance, thus addressing the limitations of existing systems.
Implementation Method 1
The wireless power transmitting capacitor electrode may transmit the wireless power to a wireless power receiving device via near field capacitive coupling
Implementation Method 2
The wireless power transmitting capacitor electrode may be mounted behind a dielectric window in a given one of the conductive housing sidewalls
Data Source
AI summary
A wireless power transmission system may include a wireless power transmitting device such as a tablet computer and a wireless power receiving device such as a computer stylus. A wireless power transmitting capacitor electrode may be formed in the tablet computer. A wireless power receiving capacitor electrode may be formed in the computer stylus. The transmitting capacitor electrode may be driven by a drive signal having a frequency of 900 MHz or greater to produce wireless power. The wireless power may be transmitted from the transmitting capacitor electrode to the receiving capacitor electrode on the stylus via near field capacitive coupling. The transmitting and receiving capacitor electrodes may each include conductive traces on dielectric substrates. The conductive traces may follow meandering paths to maximize the possible capacitive coupling efficiency between the capacitor electrodes and thus the end-to-end charging efficiency of the wireless power transmission system.