Segmented Magnetic Sheet for Non-Contact Charging Efficiency
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Solution Overview
Problem
Conventional non-contact charging methods for portable electronic devices face challenges such as insufficient power transmission due to eddy current-induced heat generation and magnetic saturation, leading to longer charging times and reduced battery life.
Innovation Solution
A magnetic sheet with a stack of 5 to 25 amorphous alloy thin strips and resin film parts, featuring cutout portions and controlled saturation magnetostriction constant, is used to enhance magnetic shielding and reduce eddy current losses, thereby improving power receiving efficiency and charging speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If a flat coil is used for non-contact charging, then the device thickness is reduced, but eddy current heat generation increases and power transmission efficiency decreases
Solution Approach 1:
The magnetic shielding layer is divided into multiple thin strips arranged in a specific pattern rather than using a continuous magnetic shield. This segmentation interrupts the eddy current paths while maintaining magnetic flux guidance, reducing eddy current losses and heat generation while preserving the thin profile needed for compact device design
Solution Approach 2:
A magnetic shielding layer is introduced as an intermediary component between the receiving coil and the device substrate. This layer mediates the magnetic field interaction by guiding magnetic flux through intended paths while blocking parasitic eddy currents in the substrate, thereby improving power transmission efficiency without increasing device thickness
2Length of stationary object
If ferrite is processed to be thin to reduce device thickness, then the device becomes more compact, but shock resistance deteriorates and reliability decreases
Solution Approach 1:
The magnetic shielding layer is constructed as a composite structure combining multiple thin magnetic strips with non-magnetic spacer materials. This composite approach maintains the overall thin profile while the distributed structure provides improved mechanical strength and shock resistance compared to a single thin ferrite layer, enhancing reliability without sacrificing compactness
3Temperature
If magnetic shielding is increased to suppress eddy current, then heat generation is reduced, but device complexity increases
Solution Approach 1:
The magnetic shielding is segmented into multiple thin strips arranged in a systematic pattern rather than using a complex three-dimensional magnetic shield structure. This segmentation achieves effective eddy current suppression through the interrupted magnetic paths while maintaining a simple planar layout that is easy to manufacture and integrate, avoiding excessive device complexity
Solution Approach 2:
The effectiveness of eddy current suppression is achieved by optimizing parameters such as the width, spacing, and arrangement pattern of the magnetic strips rather than increasing the overall magnetic shielding mass. This parameter-based approach reduces heat generation while keeping the structure simple and manufacturable, avoiding complexity increases
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 suppresses eddy current generation and magnetic saturation, resulting in increased power transmission efficiency, reduced charging time, and extended battery life, while maintaining the magnetic sheet's flexibility and usability.
Implementation Method 1
The non-contact charging method is a method in which a coil is provided in each of the power receiving device and the power feeding device, and charging is performed by utilizing an electromagnetic induction
Implementation Method 2
a magnetic sheet with a stack of 5 to 25 amorphous alloy thin strips and resin film parts, featuring cutout portions and controlled saturation magnetostriction constant, is used to enhance magnetic shielding and reduce eddy current losses
Implementation Method 3
a magnetic flux passing through the flat coil is interlinked with a substrate or the like in the apparatus, and thus there is a problem that an eddy current generated due to an electromagnetic induction causes heat generation in the apparatus
Data Source
AI summary
A magnetic sheet 1 of an embodiment includes a stack of a plurality of magnetic thin strips and resin film parts. The stack includes from 5 to 25 pieces of the magnetic thin strips. The magnetic thin strips are provided with cutout portions each having a width of 1 mm or less (including 0 (zero)). A ratio (B/A) of a total length B of the cutout portions provided to the magnetic thin strip to a total outer peripheral length A of an outer peripheral area of the magnetic thin strip arranged on one of the resin film parts is in a range of from 2 to 25.