Touch Screen Detection Using Segmented Reference Measurement
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Solution Overview
Problem
Conventional capacitive touch screens face misjudgments due to water or conductive substances on the surface, as they can mimic touch or pressure readings, leading to incorrect interpretations.
Innovation Solution
A full screen driven detection method where a driving signal is simultaneously provided to all conductive strips, allowing for the detection of mutual capacitive signals across all strips to determine if an external conductive object coupled to ground is touching or approaching, regardless of water or other conductive substances not coupled to ground.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional mutual capacitive detection is used, then touch position can be detected, but water stains or conductive substances cause misjudgment by mimicking touch signals
Solution Approach 1:
The detection process is segmented into two distinct phases: a reference measurement phase (without touch) and a detection phase (with potential touch). By comparing the current capacitive values against the reference values from the same conductive strips, the system can distinguish between capacitive changes caused by water stains (which appear in both phases) and actual touches (which appear only in the detection phase).
Solution Approach 2:
The system changes the operational state of the conductive strips by sequentially selecting different strips for measurement. By varying which conductive strips are actively measured between the reference and detection phases, the system can identify whether capacitive changes are localized (indicating a touch) or distributed (indicating water contamination).
2Use of energy by moving object
If sequential detection of conductive strips is used, then power consumption is reduced, but detection time increases
Solution Approach 1:
The system performs partial detection by measuring only selected conductive strips rather than all strips continuously. The controller sequentially activates and measures specific conductive strips based on detection needs, performing just enough measurement to determine touch status without exhaustive scanning of the entire touch screen surface.
Solution Approach 2:
The detection process uses periodic action by alternating between reference measurement cycles and detection cycles. The controller periodically switches between measuring reference capacitive values (when no touch is expected) and detecting actual touches, creating a rhythmic detection pattern that balances power consumption with detection responsiveness.
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 effectively differentiates between real and unreal touches, reducing misjudgments and enabling power-saving modes by ensuring accurate detection of external conductive objects while ignoring non-grounded conductive substances like water stains.
Implementation Method 1
capacitive coupling signals at the intersections between the first conductive strip provided with the driving signal and all the second conductive strips
Data Source
AI summary
A driving signal is simultaneously provided to all first conductive strips arranged in parallel in a first direction in a touch screen, and mutual capacitive signals are detected from all second conductive strips arranged in parallel in a second direction. The mutual capacitive signals can be used for determining whether an external conductive object coupled to the ground is touching or approaching the touch screen or not even if water or other conductive object not coupled to ground is on the touch screen.