Ferrite Cover Structure for Wireless Charging Through Metal Housings

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Solution Overview

Problem

Metallic housings in electronic devices can impede wireless power transfer unless they incorporate a window for magnetic coupling, and existing non-metallic covers may reduce coupling efficiency due to thickness, leading to suboptimal magnetic flux passage.

Innovation Solution

A non-metallic cover with ferromagnetic regions is used within the window of the housing to enhance magnetic coupling between internal and external wireless power transfer coils, providing a high magnetic permeability flux path while maintaining mechanical and moisture protection, and featuring a surface finish that matches the housing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a non-metallic cover is used to protect the wireless power transfer coil, then mechanical and moisture protection is provided, but the thickness of the cover reduces magnetic coupling between internal and external coils

Engineering Contradiction:

Improveprotection of wireless power transfer coilVSAvoidmagnetic coupling efficiency

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent applies composite materials by combining a non-metallic cover material with ferromagnetic particles to create a composite cover that provides both mechanical protection and enhanced magnetic coupling. The ferromagnetic particles embedded in the non-metallic matrix allow magnetic flux to pass more effectively through the cover while maintaining its protective function, thus resolving the contradiction between protection and coupling efficiency.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent changes the magnetic parameters of the cover by incorporating ferromagnetic particles, which alter the magnetic permeability and magnetic conductivity of the cover material. This parameter change enables the cover to transmit magnetic flux more effectively, reducing the negative impact of cover thickness on magnetic coupling while maintaining protective functionality.

Inventive Principle:

Principle #35Parameter changes

2Use of energy by moving object

If a window is incorporated in the housing to allow magnetic coupling, then wireless power transfer is enabled, but the structural integrity and protection of internal components are compromised

Engineering Contradiction:

Improvewireless power transfer capabilityVSAvoidprotection of internal components

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent uses a composite cover material containing ferromagnetic particles that provides both magnetic coupling capability and mechanical protection. This composite structure allows the housing to maintain structural integrity while enabling wireless power transfer through the cover, eliminating the need for a separate window that would compromise protection.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent makes the cover multi-functional by giving it both protective functions (mechanical and moisture protection) and magnetic coupling functions through the incorporation of ferromagnetic particles. This universal cover replaces the need for separate protective and coupling structures, maintaining both protection and wireless power transfer capability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Loss of energy

If ferromagnetic particles are added to the non-metallic cover to enhance magnetic coupling, then magnetic permeability is improved, but the manufacturing complexity increases

Engineering Contradiction:

Improvemagnetic flux passage efficiencyVSAvoidmanufacturing of non-metallic cover

Core Design Contradiction:

Loss of energyVSEase of manufacture

Solution Approach 1:

The patent incorporates ferromagnetic particles into the non-metallic cover material, creating a composite structure that can be manufactured using existing molding techniques. The particles are distributed within the matrix material, allowing the cover to be formed in a single manufacturing process that maintains relatively simple production while achieving enhanced magnetic properties.

Inventive Principle:

Principle #31Porous materials

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 improves magnetic coupling by reducing air gaps and enhancing flux path efficiency, ensuring effective wireless power transfer while maintaining protection and aesthetic coordination with the device's housing.

Implementation Method 1

The non-metallic cover incorporating at least one ferromagnetic region that improves magnetic coupling of the wireless power transfer coil to a corresponding wireless power transfer coil of another device by providing a high magnetic permeability flux path

Methodology Applied

Scientific EffectFerromagnetism: Ferromagnetism

Data Source

PatentUS20230275460A1Ferrite structure for improved magnetic coupling

Publication Date: 2023.08.31 APPLE INC

AI summary

An electronic device can include a metallic or non-metallic housing having a window therethrough, a wireless power transfer coil disposed inside the housing adjacent the window, and a non-metallic cover disposed within the window that protects the wireless power transfer coil, the non-metallic cover incorporating at least one ferromagnetic region that improves magnetic coupling of the wireless power transfer coil to a corresponding wireless power transfer coil of another device by providing a high magnetic permeability flux path. The non-metallic cover and the at least one ferromagnetic region have surface finishes selected to visually match or coordinate with the housing.