Capacitive Fold Angle Sensing in Foldable Display Layers

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Solution Overview

Problem

Foldable electronic devices rely on additional sensors like acceleration and gravity (A+G) sensors and Hall sensors for fold angle detection, which increase cost, size, and complexity, and can interfere with other components.

Innovation Solution

Utilize the existing touch controller IC to detect folding angles through mutual and self-capacitive sensing techniques, eliminating the need for dedicated sensors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If dedicated sensors (Hall sensors, A+G sensors) are used for fold angle detection, then measurement precision is improved, but device complexity increases

Engineering Contradiction:
Improvefold angle detection accuracyVSAvoidsensor system complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The touch controller is designed to perform multiple functions: it serves as both the touch input controller and the fold angle detection sensor. By making the touch controller universal, the patent eliminates the need for dedicated fold angle sensors while maintaining accurate detection capability through capacitive sensing of the folding mechanism's movement.

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

Solution Approach 2:

The touch controller performs self-service by using its own capacitive sensing capability to detect fold angle without requiring external dedicated sensors. The touch controller monitors changes in capacitance caused by the folding action, thereby serving its own additional function of fold detection.

Inventive Principle:
Principle #25Self-service

2Measurement precision

If dedicated sensors are added for fold angle detection, then measurement precision is improved, but device size increases

Engineering Contradiction:
Improvefold angle detection accuracyVSAvoiddevice size
Core Design Contradiction:
Measurement precisionVSVolume of moving object

Solution Approach 1:

The touch controller is designed to perform multiple functions: it serves as both the touch input controller and the fold angle detection sensor. By making the touch controller universal, the patent eliminates the need for dedicated fold angle sensors while maintaining accurate detection capability through capacitive sensing of the folding mechanism's movement.

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

3Measurement precision

If dedicated sensors are added for fold angle detection, then measurement precision is improved, but manufacturing cost increases

Engineering Contradiction:
Improvefold angle detection accuracyVSAvoidmanufacturing cost
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The touch controller is designed to perform multiple functions: it serves as both the touch input controller and the fold angle detection sensor. By making the touch controller universal, the patent eliminates the need for dedicated fold angle sensors while maintaining accurate detection capability through capacitive sensing of the folding mechanism's movement.

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

4Measurement precision

If additional sensors are installed for fold angle detection, then measurement precision is improved, but power consumption increases

Engineering Contradiction:
Improvefold angle detection accuracyVSAvoidpower consumption
Core Design Contradiction:
Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The touch controller performs self-service by using its own capacitive sensing capability to detect fold angle without requiring external dedicated sensors. The touch controller monitors changes in capacitance caused by the folding action, thereby serving its own additional function of fold detection.

Inventive Principle:
Principle #25Self-service

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

Accurately detects folding angles without additional sensors, reducing cost and space requirements while enhancing reliability and power efficiency.

Implementation Method 1

activating, by the touch controller, a mutual-capacitance sensing mechanism of the foldable device, wherein the activating comprises configuring one or more channels of the touch-sensing layer parallel to the folding axis on the first portion of the display layer as transmit channels, and configuring one or more channels of the touch-sensing layer parallel to the folding axis on the second portion of the display layer as receive channels

Methodology Applied
Scientific EffectMutual capacitance sensing: Capacitance

Data Source

PatentEP4685609A1Folding angle detection in a device
Publication Date: 2026.01.28 STMICROELECTRONICS INT NV
  • EP4685609A1 patent drawingFigure 1~3
  • EP4685609A1 patent drawingFigure 2A~2C
  • EP4685609A1 patent drawingFigure 4~5

AI summary

According to an embodiment, a method for determining the folding angle of a foldable device is proposed. The device includes a touch controller, a display layer, and a touch-sensing layer. The device is foldable along a folding axis. A first portion is in contact with a second portion of the display layer in a fully closed position of the device. The method includes activating a mutual-capacitance sensing mechanism by configuring one or more channels of the touch-sensing layer parallel to the folding axis on the first portion of the display layer as transmit channels, and configuring one or more channels of the touch-sensing layer parallel to the folding axis on the second portion of the display layer as receive channels; collecting mutual-capacitance raw data measurements; determining the folding angle based on the mutual-capacitance raw data measurements; and activating a function or an application based on the folding angle.