In-Cell Touch Panel Common Electrode Shielding Parasitic Capacitance
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Solution Overview
Problem
In in-cell touch display panels, the proximity of touch electrodes to pixel circuits leads to signal distortion due to parasitic capacitance, affecting touch signal accuracy.
Innovation Solution
The design incorporates a substrate with touch signal lines, sub-pixels, touch electrode groups, and a common signal array, where the common signal array overlaps more sub-pixels than touch electrode groups, reducing parasitic capacitance between data lines, scan lines, and touch electrodes by strategically positioning common electrodes to minimize interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If touch electrodes are integrated into the display panel (in-cell touch), then the panel thickness is reduced, but parasitic capacitance between touch electrodes and pixel circuits increases causing signal distortion
Solution Approach 1:
A common electrode is introduced as an intermediary element between the touch electrode and the pixel circuit. This common electrode overlaps with the data line and scan line to provide a shielding effect, acting as a mediator that reduces the parasitic capacitance coupling between the touch electrode and the pixel circuit signals, thereby reducing signal distortion while maintaining the in-cell thin structure.
2Object-affected harmful factors
If common electrodes overlap data lines and scan lines, then parasitic capacitance is reduced, but the number of sub-pixels covered increases
Solution Approach 1:
The common electrode is strategically positioned to overlap specifically with the data line and scan line regions where parasitic capacitance is most problematic. By concentrating the shielding effect in these critical local areas rather than uniformly across all sub-pixels, the design reduces parasitic capacitance where it matters most while minimizing the impact on the overall display area and number of sub-pixels.
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 configuration effectively reduces parasitic capacitance, enhancing touch signal accuracy and minimizing interference with pixel circuit signals, thereby improving the overall performance of the touch panel.
Implementation Method 1
parasitic capacitance between a data line and a touch electrode or a parasitic capacitance between a scan line and a touch electrode
Data Source
AI summary
A touch panel includes a substrate, touch signal lines, sub-pixels, touch electrode groups, and at least one common signal array. The touch signal lines and the sub-pixels are located on substrate. Each of the sub-pixels includes a switch element and a pixel electrode. The switch element is electrically connected to a corresponding scan line and a corresponding data line. The touch electrode groups include touch electrodes. The touch electrodes overlap the pixel electrodes of the sub-pixels. Each of the touch electrode groups is electrically connected to a corresponding one of the touch signal lines. The common signal array includes common electrodes. Each of the common electrodes overlaps at least one of the scan line and the data line. The number of the sub-pixels overlapped by the common signal array is greater than the number of the sub-pixels overlapped by each of the touch electrode groups.