Capacitive Fold Angle Detection for Foldable Devices

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Solution Overview

Problem

Conventional foldable devices rely on gyroscopic sensors, accelerometers, and IR or Hall sensors to detect fold angles, which are prone to temperature sensitivity and display noise issues, necessitating heavy filtering and increasing complexity and cost.

Innovation Solution

A system utilizing a capacitive sensor array to determine fold angles by obtaining transcapacitance and absolute capacitance measurements, canceling out interference from input objects, and using baseline reference measurements to accurately detect the fold angle without additional sensors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If gyroscopic sensors and accelerometers are used to detect fold angle, then fold angle detection capability is achieved, but device complexity and cost increase

Engineering Contradiction:

Improvefold angle detection reliabilityVSAvoidsensor system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The capacitive sensor array originally designed for touch detection is made multi-functional by enabling it to perform both touch sensing and fold angle detection. The same electrodes and signal processing circuitry are used for both purposes, eliminating the need for separate gyroscopic sensors and accelerometers.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The foldable device uses its own existing capacitive touchscreen infrastructure to detect fold angle, rather than relying on external or additional sensors. The device's built-in sensor array serves itself for multiple detection functions.

Inventive Principle:

Principle #25Self-service

2Reliability

If IR sensors or Hall sensors are used to detect closure, then closure detection is achieved, but device complexity and cost increase

Engineering Contradiction:

Improveclosure detection reliabilityVSAvoidsensor system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The capacitive sensor array is made multi-functional to perform both touch sensing and closure detection, eliminating the need for separate IR sensors or Hall sensors. The same hardware infrastructure serves multiple detection purposes.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Device complexity

If conventional capacitive sensors are used for fold angle detection, then sensor integration is achieved, but temperature sensitivity and display noise interfere with measurement precision

Engineering Contradiction:

Improvesensor system integrationVSAvoidfold angle measurement precision

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent extracts and removes the harmful interference components (temperature sensitivity effects and display noise) from the capacitive sensor measurements through signal processing techniques, isolating the pure fold angle detection signal from the noisy raw data.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The system uses feedback mechanisms to continuously monitor and compensate for temperature variations and display noise effects on the capacitive sensor readings, adjusting the measurements to maintain precision despite environmental interference.

Inventive Principle:

Principle #23Feedback

4Measurement precision

If heavy filtering is applied to remove temperature sensitivity and display noise, then measurement precision is improved, but processing time and complexity increase

Engineering Contradiction:

Improvefold angle measurement precisionVSAvoidsignal processing complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex mechanical filtering hardware with software-based signal processing algorithms that can be implemented in the device's existing processor, reducing hardware complexity while maintaining filtering effectiveness.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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

This approach simplifies fold angle detection, reduces material and assembly costs, enhances reliability, and avoids display interference, enabling accurate fold angle determination even with input objects present, while eliminating the need for additional sensors.

Implementation Method 1

Capacitive detection of fold angle for foldable devices

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 2

obtain transcapacitance measurements via a subset of the plurality of electrodes; obtain absolute capacitance measurements via the subset of the plurality of electrodes

Methodology Applied

Scientific EffectCapacitive sensing: Capacitance

Data Source

PatentUS12141000B2Capacitive detection of fold angle for foldable devices

Publication Date: 2024.11.12 SYNAPTICS INC

AI summary

A system for determining a fold angle of a foldable device, the system including a plurality of electrodes and a processing system, wherein the processing system is configured to obtain transcapacitance measurements via a subset of the plurality of electrodes; obtain absolute capacitance measurements via the subset of the plurality of electrodes; and determine the fold angle of the foldable device based on the transcapacitance measurements and the absolute capacitance measurements.