Capacitive Sensor Touch Detection Using Rate of Change
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing touch input detection methods using capacitive sensing are prone to false inputs and failure to register actual inputs due to manufacturing tolerances and environmental changes, as they rely on approximate reference values.
Innovation Solution
The method involves detecting a touch condition based on the rate of change of electrode capacitance and evaluating it after detection, conserving computing resources by deferring evaluation until the touch condition is met, and providing additional data for accurate stimulus determination, applicable to capacitive and optical sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional capacitive sensing techniques are used with reference values, then touch inputs can be detected, but false touch inputs occur or actual touch inputs fail to register due to manufacturing tolerances and environmental changes
Solution Approach 1:
The system performs preliminary characterization of capacitive sensors during manufacturing to establish baseline capacitance values and rate-of-change characteristics. This preliminary action creates reference data that accounts for manufacturing tolerances, enabling more accurate touch detection during actual use despite variations in sensor characteristics.
Solution Approach 2:
The invention transitions from using static reference capacitance values to using dynamic rate-of-change measurements (dC/dt). By measuring how capacitance changes over time rather than comparing absolute capacitance values, the system becomes insensitive to manufacturing tolerances and environmental drift, significantly improving measurement precision and reliability.
2Measurement precision
If continuous evaluation of touch conditions is performed, then accurate stimulus determination is achieved, but computing resources are consumed
Solution Approach 1:
The system uses periodic sampling of capacitive values at multiple time points to detect touch conditions. By sampling at specific intervals and analyzing the rate of change between samples, the system achieves accurate touch detection while minimizing the frequency of evaluations, thus conserving computing resources compared to continuous evaluation.
Solution Approach 2:
The invention extracts only the essential information needed for touch detection by focusing on the rate of change of capacitance (dC/dt) rather than analyzing complete capacitive profiles. This extraction of critical features enables accurate touch condition determination with minimal computational effort, reducing energy consumption while maintaining detection accuracy.
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 enhances the reliability and consistency of touch input detection by accurately registering touch conditions and preventing false inputs, improving the accuracy of fingerprint recognition and other biometric data collection.
Implementation Method 1
Touch inputs can be determined based on a capacitive output of an electrode
Data Source
AI summary
A method for determining a stimulus is provided. The method includes determining a touch condition based on the rate of change of electrode capacitance, measuring a characteristic of the electrode capacitance in response to the touch condition being met, and evaluating the measured characteristic to determine the touch stimulus. The method can improve the ability to determine a touch stimulus over existing methods, including the ability to determine fingerprint and handprint biometrics, for example.