Capacitive Fold Angle Detection Using Temperature-Compensated Baseline Calibration
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Solution Overview
Problem
Conventional foldable devices do not effectively utilize their capacitive sensors to detect the fold angle due to issues like temperature sensitivity and display noise, requiring additional sensors such as gyroscopic sensors, accelerometers, IR sensors, or Hall sensors.
Innovation Solution
A system using a plurality of electrodes and a processing system to determine the fold angle by obtaining baseline capacitance measurements, updating them based on temperature changes, and combining absolute and transcapacitance measurements to accurately detect the fold angle without external 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 patent divides the capacitive sensor array into multiple regions (first region and second region) with different functions. The first region is optimized for touch sensing while the second region is optimized for fold angle detection. This segmentation allows each region to be tuned for its specific purpose, improving fold angle detection precision while using the existing capacitive sensor infrastructure.
Solution Approach 2:
Different regions of the capacitive sensor are assigned different characteristics. The second region has modified electrode patterns and spacing optimized for detecting fold angle changes, while the first region maintains standard touch sensing characteristics. This local optimization enables accurate fold angle detection without compromising touch functionality.
Solution Approach 3:
The patent introduces a dedicated processing circuit that acts as an intermediary between the capacitive sensor and the main processor. This circuit specifically processes signals from the second region to extract fold angle information, filtering out noise and temperature effects before data reaches the main system.
2Measurement precision
If dedicated sensors (gyroscopic, accelerometer, IR, Hall) are added to detect fold angle, then measurement precision is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent makes the capacitive sensor array multi-functional by enabling it to perform both touch sensing and fold angle detection. The second region of the capacitive sensor serves dual purposes: it can detect touch inputs when needed and measure fold angle changes when the device is folded, eliminating the need for separate dedicated sensors.
Solution Approach 2:
The capacitive sensor system serves itself by using its existing infrastructure to detect fold angle. The device uses its own capacitive sensing capability to monitor the fold state, rather than requiring external dedicated sensors. This self-service approach reduces component count while maintaining functionality.
3Ease of manufacture
If capacitive sensors are used for fold angle detection, then manufacturing cost is reduced, but reliability deteriorates due to temperature drift and user input interference
Solution Approach 1:
By segmenting the capacitive sensor into functional regions, the patent isolates fold angle detection to a specific area that can be optimized for stability. The first region handles touch inputs while the second region focuses on fold angle, allowing each to be tuned for its specific reliability requirements.
Solution Approach 2:
The processing circuit continuously monitors capacitance changes in the second region and uses feedback mechanisms to distinguish between legitimate fold angle changes and spurious signals from temperature drift or user input. This feedback loop filters out false positives and maintains detection reliability.
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 accurate and timely fold angle detection in foldable devices, reducing material costs, assembly labor, and improving reliability by eliminating the need for additional sensors and minimizing interference from temperature drift and user input.
Implementation Method 1
issues such as temperature sensitivity
Implementation Method 2
obtain, via a subset of the plurality of electrodes, baseline reference absolute capacitance measurements
Implementation Method 3
the capacitive sensor(s) to detect a fold angle of the foldable device
Data Source
AI summary
A system for determining a fold angle of a foldable device includes a plurality of electrodes and a processing system. The processing system is configured to: determine a first detected temperature at a first time; obtain baseline reference absolute capacitance measurements associated with the first detected temperature and associated with a known fold angle of the foldable device; determine a second detected temperature at a second time later than the first time; obtain absolute capacitance measurements associated with the second detected temperature at the second time; generate updated baseline reference absolute capacitance measurements based on the obtained capacitive measurements associated with the second detected temperature at the second time; obtain absolute capacitance measurements at a third time later than the second time; and determine the fold angle of the foldable device based on the absolute capacitance measurements obtained at the third time and the updated baseline reference absolute capacitance measurements.