Flexible Substrate Coil Unit for Foreign Object Detection
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Solution Overview
Problem
Existing contactless power transmission systems face challenges in detecting foreign objects between coils, leading to heating issues and inefficiencies due to the need for downsized components and interference from rigid substrates affecting magnetic fields.
Innovation Solution
A coil unit with a flat coil, a magnetic substance, a flexible substrate, and a temperature detection element, where the flexible substrate is positioned parallel to the coil and the temperature detection element is integrated within the air-core, allowing for efficient detection of foreign objects and maintaining slimness while improving transmission efficiency by minimizing substrate interference with magnetic fields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a rigid substrate is used to mount the temperature detection element, then the detection function is achieved, but the coil unit thickness increases and magnetic field interference occurs
Solution Approach 1:
The patent employs a flexible substrate instead of a rigid substrate to mount the temperature detection element. This flexible substrate can be made extremely thin while maintaining structural integrity, thus achieving the detection function without significantly increasing the coil unit thickness. The flexibility also allows it to conform to the coil structure without causing magnetic field interference.
Solution Approach 2:
The temperature detection element is positioned in the air-core region of the flat coil, utilizing the three-dimensional space within the coil structure rather than adding thickness in a linear direction. This spatial arrangement allows detection functionality to be integrated without proportionally increasing overall thickness.
2Measurement precision
If the substrate is positioned on the transmission surface of the coil, then the detection element is close to the coil for effective detection, but the substrate interferes with the magnetic field and reduces transmission efficiency
Solution Approach 1:
The substrate is segmented into two distinct functional zones: one side positioned near the transmission surface for temperature detection, and the other side positioned near the non-transmission surface to avoid magnetic field interference. This segmentation allows the substrate to fulfill both detection and non-interference requirements simultaneously.
Solution Approach 2:
The flexible substrate acts as an intermediary element that bridges the temperature detection requirement and the magnetic field protection requirement. By positioning it to extend from the transmission surface toward the non-transmission surface, it enables detection while minimizing interference with the magnetic field.
3Volume of moving object
If the coil unit is downsized for mobile device integration, then device compactness is improved, but foreign object detection reliability is reduced
Solution Approach 1:
The flexible substrate enables the temperature detection element to be integrated into the compact coil unit structure without requiring additional space in the thickness direction. This allows the coil unit to maintain a small size suitable for mobile devices while still incorporating reliable foreign object detection capability.
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
The solution effectively detects foreign objects and enhances transmission efficiency by reducing the distance between coils and minimizing substrate interference, ensuring reliable operation and efficient power transfer while maintaining a slim design.
Implementation Method 1
contactless power transmission that uses electromagnetic induction to transmit power without using a metal contact
Implementation Method 2
a magnetic substance for forming a magnetic path for the flat coil
Implementation Method 3
when a foreign object such as a metal piece intrudes into the gap between the primary coil and secondary coil during contactless power transmission, the foreign object generates an eddy current thereby causing heating
Data Source
AI summary
A coil unit includes a coil including a coil wire, a magnetic substance for receiving magnetic force lines generated by the coil, a first substrate, and a temperature detection element disposed on the first substrate.