Multi-Coil Charging Surface Using Voltage-Based Motion Detection

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Solution Overview

Problem

Existing wireless charging systems struggle to efficiently charge devices with varying form factors and locations on multi-coil charging surfaces, often requiring precise device placement and lacking accuracy in detecting device position and movement.

Innovation Solution

A multi-coil wireless charging system with a free-positioning charging surface that uses capacitive, resistive, inductive, touch, pressure, or strain sensing to detect device location, and selectively activates coils through a matrix multiplexed switching system to optimize power transfer, allowing devices to be charged without precise alignment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple charging coils are used to support various device locations, then charging versatility is improved, but device complexity increases

Engineering Contradiction:
Improvecharging versatilityVSAvoiddevice complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The charging surface is divided into multiple independent charging coils arranged in a grid pattern, allowing selective activation of individual coils or combinations of coils based on device position and size. This segmentation enables versatile charging configurations without requiring all coils to be active simultaneously, managing system complexity through modular operation.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system dynamically selects and activates specific charging coils based on real-time detection of device location, size, and power requirements. The controller adjusts which coils are active and at what power levels, providing adaptability while managing complexity through intelligent control rather than fixed configurations.

Inventive Principle:
Principle #15Dynamics

2Productivity

If device position detection accuracy is improved, then charging efficiency is improved, but measurement precision requirements increase system complexity

Engineering Contradiction:
Improvecharging efficiencyVSAvoiddevice position detection accuracy
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The charging coils serve dual functions: both power transmission and position detection. By monitoring impedance changes, voltage variations, and current characteristics of each coil, the system determines device location without requiring separate sensor arrays. This multi-functionality improves charging efficiency while avoiding the complexity of dedicated detection systems.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system continuously monitors electrical characteristics of charging coils and uses this feedback to refine position detection accuracy. By analyzing changes in coil impedance, voltage, and current as devices are placed or moved, the controller dynamically adjusts its understanding of device position, improving detection accuracy through iterative measurement rather than requiring high-precision sensors from the start.

Inventive Principle:
Principle #23Feedback

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 and flexible charging of devices with varying sizes and shapes, supporting multiple devices simultaneously, while dynamically adjusting power transfer based on device movement and position for optimal efficiency.

Implementation Method 1

a controller to provide a charging current to at least one active transmitting coil in the charging surface

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

uses capacitive, resistive, inductive, touch, pressure, or strain sensing to detect device location

Methodology Applied
Scientific EffectCapacitive sensing: Capacitance

Implementation Method 3

uses capacitive, resistive, inductive, touch, pressure, or strain sensing to detect device location

Methodology Applied
Scientific EffectResistive sensing: Electrical Resistance

Implementation Method 4

uses capacitive, resistive, inductive, touch, pressure, or strain sensing to detect device location

Methodology Applied
Scientific EffectInductive sensing: Electromagnetic Induction

Implementation Method 5

uses capacitive, resistive, inductive, touch, pressure, or strain sensing to detect device location

Methodology Applied
Scientific EffectPressure sensing: Pressure Increase

Data Source

PatentEP4088146B1Device movement detection in a multi-coil charging surface
Publication Date: 2025.08.13 AIRA INC
  • EP4088146B1 patent drawingFigure 1
  • EP4088146B1 patent drawingFigure 2
  • EP4088146B1 patent drawingFigure 3

AI summary

Systems, methods and apparatus for wireless charging are disclosed. A charging device has a plurality of charging cells provided on a charging surface provided at a charging surface of the wireless charging device, and a controller. The controller may be configured to provide a charging current to at least one active transmitting coil in the charging surface, measure voltages across three or more transmitting coils in the charging surface and determine that the chargeable device is in motion across the charging surface based on changes in the voltages measured across the three or more transmitting coils. The charging current may cause a wireless transfer of power through the at least one active transmitting coil to a chargeable device located on the charging surface.