Touch Sensor Voltage Threshold Staging for Low-Power Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing touch sensors in electronic devices face challenges in accurately detecting touch contacts during low-power operating modes, leading to potential false positives and increased power consumption due to frequent voltage threshold comparisons.
Innovation Solution
A method involving a touch sensor that compares a voltage across a capacitor with multiple voltage thresholds, where the second threshold is higher and reached within a shorter duration, and repeated comparisons are conducted to confirm touch contact, using a digital-to-analog converter and Schmitt trigger thresholds to optimize detection accuracy and power efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single voltage threshold comparison is used for touch detection, then the detection speed is fast, but the measurement precision is insufficient leading to false positives
Solution Approach 1:
The detection process is segmented into multiple sequential stages: a first comparison step with a first voltage threshold, followed by a second comparison step with a second voltage threshold (higher than the first) only if the first threshold is reached within a duration shorter than a first duration threshold. This segmentation allows progressive verification of touch contact, improving accuracy while controlling complexity through conditional execution.
Solution Approach 2:
The first voltage threshold comparison serves as a preliminary screening step that quickly identifies potential touch contacts. Only when this preliminary condition is met (threshold reached within duration threshold) does the system proceed to the more rigorous second comparison step, efficiently filtering out false positives before committing additional processing resources.
2Reliability
If frequent voltage threshold comparisons are performed to improve detection reliability, then the reliability improves, but the power consumption increases
Solution Approach 1:
The sensor operates in low-power operating modes between periodic detection cycles. During these low-power modes, the sensor periodically performs the multi-step voltage threshold comparison method to detect touch contacts while maintaining overall low power consumption. The periodic execution of detection steps balances reliability requirements with energy efficiency.
Solution Approach 2:
The system performs partial verification through the two-step threshold comparison process. The first comparison step provides quick screening, and the second step provides additional verification only when needed. This partial action approach achieves sufficient detection reliability without performing excessive comparisons that would unnecessarily increase power consumption.
3Measurement precision
If multiple voltage threshold comparisons are implemented to reduce false positives, then the measurement precision improves, but the detection time increases
Solution Approach 1:
The detection method dynamically adapts its verification depth based on the results of the first comparison step. When the first threshold is reached quickly (within the first duration threshold), the system proceeds to the second comparison step for enhanced accuracy. This dynamic approach ensures that full verification is performed only when initially suspicious of a valid touch contact, reducing false positives while minimizing detection time for clear cases.
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 reduces false positives and decreases power consumption by accurately detecting touch contacts while maintaining low-power operating modes, ensuring reliable and efficient sensor operation.
Implementation Method 1
the voltage is the voltage across a capacitor
Implementation Method 2
at least one of the voltage thresholds is the threshold of a Schmitt trigger
Data Source
AI summary
An embodiment of the present disclosure relates to a method of detection of a touch contact by a sensor including a first step of comparison of a voltage with a first voltage threshold; and a second step of comparison of the voltage with a second voltage threshold, the second step being implemented if the first voltage threshold has been reached within a duration shorter than a first duration threshold, the second voltage threshold being higher than the first voltage threshold.