Touch-Screen Coupling Correction via Row Electrode Signaling
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Solution Overview
Problem
The thin dielectric layer in capacitive touch screens leads to strong capacitive coupling between touch-screen and display electrodes, reducing touch sensitivity due to an undesirable low-impedance path, which affects the accuracy of touch sensing.
Innovation Solution
A row-driving scheme is implemented where one or more row electrodes are excited while others remain undriven, allowing for the sensing of signals on undriven row electrodes to estimate and compensate for the undesired component in the column-electrode signal, improving touch sensitivity by providing a corrected output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If a thin dielectric layer is used to reduce device thickness, then device integration is improved, but capacitive coupling between touch-screen and display electrodes increases, reducing touch sensitivity
Solution Approach 1:
The patent introduces an intermediary measurement approach by sensing signals on undriven row electrodes to estimate the capacitive coupling effect. This intermediary measurement allows the system to characterize the coupling between touch-screen and display electrodes without directly measuring the problematic low-impedance path, enabling compensation while maintaining the thin dielectric structure.
Solution Approach 2:
The patent implements feedback by using signals from undriven row electrodes to estimate the undesired capacitive coupling component, then feeding this estimate back to correct the column-electrode touch signals. This feedback mechanism allows real-time compensation for the coupling effect, maintaining touch sensitivity despite the thin dielectric layer causing strong coupling.
2Measurement precision
If capacitive coupling between touch-screen and display electrodes is reduced, then touch sensitivity is improved, but device thickness increases due to thicker dielectric layer
Solution Approach 1:
The patent converts the harmful capacitive coupling effect into a useful signal source. By sensing signals on undriven row electrodes, the system harvests information about the coupling strength and uses this to correct touch measurements. The harmful coupling effect becomes the basis for estimating and compensating the interference, turning a problem into a solution.
Solution Approach 2:
The patent replaces the mechanical approach of increasing dielectric thickness to reduce coupling with an electrical signal processing approach. Instead of physically separating electrodes further, the system uses electronic correction based on intermediary measurements to eliminate the coupling effect, achieving the same goal without mechanical changes.
3Device complexity
If conventional touch sensing is used without correction, then device complexity is minimized, but touch detection accuracy deteriorates due to capacitive coupling
Solution Approach 1:
The patent makes the row electrodes multi-functional: they serve both as driven electrodes for normal display operation and as sensing electrodes for estimating capacitive coupling. This universal use of existing electrodes adds the correction capability without requiring separate dedicated sensing elements, minimizing the increase in device complexity.
Solution Approach 2:
The patent performs preliminary estimation of the capacitive coupling effect by sensing signals on undriven row electrodes before correcting the touch measurement. This preliminary action allows the system to prepare the correction factor in advance, improving touch detection accuracy without adding complex real-time processing during the actual touch measurement.
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 touch sensitivity by compensating for the undesired component in real-time, reducing the impact of capacitive coupling and improving the accuracy of touch detection.
Implementation Method 1
A row-drive circuit is configured to concurrently drive one or more row electrodes while leaving undriven one or more other row electrodes
Implementation Method 2
the electrical impedance at each crossing of a row and column electrode is responsive to the proximity of a touch input to that crossing
Data Source
AI summary
A method to process touch input on a touch-screen display device having an electronic display layer arranged behind a series of column electrodes and behind a series of row electrodes. The method comprises: concurrently driving one or more row electrodes while leaving undriven one or more other row electrodes; sensing a row signal from the one or more other row electrodes; sensing a column signal from the series of column electrodes; and providing a corrected column output based at least partly on the column signal and on the row signal.