Touchscreen Row-Drive Compensation for Display Electrode Coupling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In thin capacitive touch-screen display stacks, capacitive coupling between touch-screen and display electrodes via the common electrode creates an undesired low-impedance path, reducing touch sensitivity and making the system susceptible to operational variables.
Innovation Solution
Implementing a row-driving scheme with compensation signals and modulation frequency adjustment to estimate and correct the undesired component in the column signal, either by intermittently lowering modulation frequency for re-sampling or applying out-of-phase compensation signals to non-excited row electrodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a touch-sensitive display is constructed with a touch-sensitive layer and a display layer separated by a spacing layer, then the display can provide touch sensitivity and visual output functions, but coupling between the display electrode and the touch-sensitive layer causes distorted capacitive measurements and reduced touch sensitivity
Solution Approach 1:
The patent extracts the problematic display electrode from the traditional configuration and replaces it with a dedicated sensing electrode in the touch-sensitive layer. This separation eliminates the capacitive coupling distortion caused by the display electrode while maintaining the display function, thereby resolving the technical contradiction between touch sensitivity and capacitive coupling distortion.
Solution Approach 2:
The patent introduces a ground electrode as an intermediary element positioned between the sensing electrode and the display electrode. This ground electrode acts as a shield to reduce parasitic capacitance and eliminate capacitive coupling distortion, improving touch sensitivity while maintaining system functionality.
2Illumination intensity
If the display electrode is positioned close to the touch-sensitive layer to improve display performance, then visual output quality improves, but capacitive coupling increases causing measurement distortion
Solution Approach 1:
The patent removes the display electrode from its traditional position close to the touch-sensitive layer and replaces it with a dedicated sensing electrode. This extraction eliminates the capacitive coupling that occurs when the display electrode is positioned close to the touch-sensitive layer, thereby maintaining display brightness while improving capacitive measurement accuracy.
Solution Approach 2:
The ground electrode serves as an intermediary that allows the display electrode to be positioned close to the touch-sensitive layer for optimal display performance while shielding against capacitive coupling. This mediator enables both high display brightness and accurate capacitive measurements to coexist.
3Stability of the object's composition
If traditional touch-screen construction with separate touch-sensitive layer and display layer is used, then structural organization is achieved, but parasitic capacitance reduces touch sensitivity
Solution Approach 1:
The patent merges the display and touch sensing functions into a single integrated layer structure. The display electrode pattern is formed directly in the touch-sensitive layer, eliminating the need for separate touch-sensitive and display layers. This merging reduces parasitic capacitance while maintaining structural organization, thereby improving touch sensitivity.
Solution Approach 2:
The ground electrode pattern acts as an intermediary that reduces parasitic capacitance between the sensing electrode and underlying structures. By positioning ground electrodes strategically within the integrated layer, the patent maintains structural organization while minimizing parasitic effects that would otherwise reduce touch sensitivity.
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
Improves touch sensitivity by reducing the impact of capacitive coupling, enhancing the system's ability to accurately detect touch inputs and maintain sensitivity across varying conditions.
Implementation Method 1
a sensing electrode in the touch-sensitive layer to detect touch input
Implementation Method 2
a ground electrode positioned between the sensing electrode and the display electrode to reduce parasitic capacitance
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A touch-screen display device comprises a series of column electrodes and a series of row electrodes, with an electronic display layer arranged behind the series of column electrodes and behind the series of row electrodes. The series of row electrodes crosses the series of column electrodes such that the electrical impedance at each crossing of a row and column electrode is responsive to the proximity of a touch input to that crossing. A row-drive circuit is configured to apply an excitation signal to a selected row electrode and to concurrently apply a compensation signal to one or more other row electrodes, the compensation signal being out of phase with respect to the excitation signal. A column-sense circuit is configured to sense a column signal from the series of column electrodes and to provide a corresponding column output.