Capacitive Fold Angle Detection via Differential Electrode Segmentation
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Solution Overview
Problem
Conventional foldable devices do not effectively utilize capacitive sensors to detect the fold angle due to issues like temperature sensitivity and display noise, requiring additional sensors such as gyroscopic, accelerometers, IR, or Hall sensors.
Innovation Solution
A system using a plurality of electrodes, including at least one first electrode and one second electrode positioned relative to the fold line, with a processing system to obtain absolute capacitance measurements from both electrodes to determine the fold angle, canceling out interference effects and eliminating the need for dedicated sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If capacitive sensors are used to detect fold angle, then device complexity is reduced, but measurement precision deteriorates due to temperature sensitivity and display noise
Solution Approach 1:
The sensor array is segmented into multiple electrodes (first electrode near the fold line and second electrode farther from the fold line) to enable differential measurement. This segmentation allows the system to isolate the fold angle signal from common interference by comparing measurements from different locations, thereby maintaining measurement precision while using a simpler capacitive sensor architecture.
Solution Approach 2:
The second electrode acts as an intermediary reference that experiences the same temperature and display noise effects as the first electrode but to a lesser extent. By using the second electrode's measurement as a reference, the system can cancel out common interference effects (temperature sensitivity and display noise) through differential processing, thus achieving accurate fold angle detection without requiring complex compensation mechanisms.
2Measurement precision
If dedicated sensors (gyroscopic, accelerometer, IR, Hall) are used to detect fold angle, then measurement precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The capacitive sensor array, originally designed for touch input functionality, is made multi-functional by enabling it to also detect fold angle. By utilizing the same electrode structure for both touch sensing and fold detection, the system eliminates the need for dedicated fold angle sensors (gyroscopic, accelerometer, IR, or Hall sensors), thereby reducing device complexity while maintaining measurement precision through proper electrode placement and differential measurement techniques.
Solution Approach 2:
The capacitive sensor array serves itself by performing dual functions: touch input detection and fold angle measurement. The system uses its own existing components (electrodes) to achieve fold angle detection without requiring external dedicated sensors, thus simplifying the overall system while maintaining accurate measurement capability.
3Measurement precision
If filtering is applied to reduce temperature sensitivity and display noise, then measurement precision is improved, but processing time and computational complexity increase
Solution Approach 1:
The system performs preliminary action by obtaining measurements from both the first and second electrodes simultaneously at each moment in time. This preliminary dual-measurement approach enables the system to have ready-to-use reference data for interference cancellation without requiring time-consuming post-processing filtering. The differential measurement is performed in parallel with the primary touch sensing operation, minimizing additional processing time.
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 the fold angle of foldable devices without temperature sensitivity and display noise issues, reducing material costs, assembly labor, and simplifying design while improving reliability by using capacitive sensors for fold angle detection.
Implementation Method 1
obtain at least one first absolute capacitance measurement via the at least one first electrode and at least one second absolute capacitance measurement via the at least one second electrode
Data Source
AI summary
A system for determining an open or closed state of a foldable device includes: a plurality of electrodes, including a first set of electrodes for performing absolute capacitance sensing for open/close detection, wherein each of the first set of electrodes is located proximate to an edge of the foldable device; and a processing system, configured to: obtain at least one first absolute capacitance measurement via the first set of electrodes; and determine whether the foldable device is in an open state or a closed state based on the at least one first absolute capacitance measurement.