Inductive Coil Assemblies for Wearable Power Transfer

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Solution Overview

Problem

Wearable electronic devices face limitations in power transfer due to restricted interface areas between accessories and main devices, particularly when accessories are secured in slots, which limits the use of electrical contacts and requires water-resistant connections.

Innovation Solution

The implementation of inductive coil assemblies that extend along the sidewalls of slots and attachment regions, utilizing ferrite cores with wrapped wire coils, allowing for wireless power transfer between the device and accessory while maintaining mechanical retention features.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If electrical contacts such as pads or pins are used for power transfer, then power transfer efficiency is improved, but the interface area requirement increases and water resistance becomes difficult to maintain

Engineering Contradiction:

Improvepower transfer efficiencyVSAvoidinterface area

Core Design Contradiction:

PowerVSArea of stationary object

Solution Approach 1:

The patent replaces mechanical electrical contacts (pads or pins) with an inductive power transfer system using electromagnetic fields. The first inductive coil assembly in the device and the second inductive coil assembly in the accessory enable wireless power transfer without physical electrical contacts, thus maintaining water resistance while providing sufficient power transfer through electromagnetic induction.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If inductive coils are used for power transfer, then water resistance is maintained and no exposed electrical contacts are needed, but the power transfer capability is limited by coil size and distance

Engineering Contradiction:

Improvewater resistanceVSAvoidpower transfer capability

Core Design Contradiction:

ReliabilityVSPower

Solution Approach 1:

The patent divides the inductive coil system into two separate coil assemblies: a first inductive coil assembly integrated into the device and a second inductive coil assembly integrated into the accessory. This segmentation allows each coil to be optimized independently for size and positioning, maximizing power transfer capability within the constrained interface area while maintaining the water-resistant benefit of no exposed contacts.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent extends the inductive coil assemblies along the longitudinal axis of the slot and attachment region, utilizing the third dimension (length) to maximize the effective coil area within the limited interface footprint. This dimensional optimization enhances magnetic flux coupling and power transfer capability without increasing the lateral interface area or requiring exposed electrical contacts.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Volume of moving object

If the interface area is limited to slot dimensions, then device compactness is improved, but the space available for both retention features and inductive coils is reduced

Engineering Contradiction:

Improvedevice compactnessVSAvoidspace for coils and retention features

Core Design Contradiction:

Volume of moving objectVSVolume of stationary object

Solution Approach 1:

The patent positions the inductive coil assemblies asymmetrically within the slot and attachment region, placing them along the sidewalls rather than centrally. This asymmetric arrangement optimizes the distribution of space, allowing the coil assemblies to extend along the longitudinal axis while leaving room for retention features, thereby maximizing both power transfer capability and mechanical retention within the compact interface area.

Inventive Principle:

Principle #4Asymmetry

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

Enables efficient wireless power transfer between wearable devices and accessories, even in water-resistant conditions, by optimizing the use of available space within the slot and attachment region, enhancing the functionality and durability of wearable electronics.

Implementation Method 1

Inductive power transfer, in which power is transferred between respective wire coils (referred to as 'inductive coils') in the two devices using electromagnetic induction

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

utilizing ferrite cores with wrapped wire coils

Methodology Applied

Scientific EffectFerromagnetism: Ferromagnetism

Data Source

PatentUS20240106270A1Inductive coil assemblies for electronic devices and accessories

Publication Date: 2024.03.28 APPLE INC

AI summary

Inductive coil assemblies for wireless power transfer can be provided for an electronic device having a slot to receive an accessory and an accessory having an attachment region that is insertable into the slot. The inductive coil assembly of the device can extend along a sidewall of the slot. The inductive coil assembly of the accessory can extend along one side surface of the attachment region of the accessory. The opposite sidewall of the slot and side surface of the attachment region of the accessory can provide mechanical retention features.