Touch Electrode Multiplexed as Common Electrode
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Solution Overview
Problem
VA liquid crystal display panels, particularly in capacitive touch mode, experience reduced touch effectiveness due to the entire-surface common electrode on the color film side, which interferes with touch functionality.
Innovation Solution
A touch display panel design where the touch structure layer, including a touch electrode and trace, is integrated within the thin film transistor layer on the substrate close to the liquid crystal, allowing the touch electrode to function as a common electrode, reducing interference from the common electrode of the opposing substrate and enhancing touch performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an entire-surface common electrode is placed on the color film side of a VA display mode liquid crystal display panel, then the display function is achieved, but the touch effect is shielded and reduced
Solution Approach 1:
The patent extracts the common electrode function from the color film side and relocates it to the array substrate side, where it is integrated with the touch electrode. This separation removes the harmful shielding effect on touch functionality while preserving the display function through the liquid crystal layer's optical modulation capability
Solution Approach 2:
The patent merges the common electrode and touch electrode into a single integrated structure on the array substrate. The touch electrode pattern serves dual purposes: as the common electrode for liquid crystal switching and as the touch sensing electrode, thereby eliminating the need for a separate full-surface common electrode that would interfere with touch detection
2Reliability
If the touch structure layer is integrated within the thin film transistor layer on the substrate close to the liquid crystal, then the touch electrode can function as a common electrode improving touch effectiveness, but the structure becomes more complex
Solution Approach 1:
The touch electrode pattern is designed to perform multiple functions simultaneously: it serves as the common electrode for liquid crystal switching, as the touch sensing electrode for detecting user input, and as part of the thin film transistor layer structure. This multi-functionality reduces the need for additional separate components
Solution Approach 2:
The touch electrode is segmented into a patterned structure with conductive regions and insulating regions, allowing different areas to serve different functions - the conductive regions act as common electrode areas while the patterned structure enables touch sensitivity in specific zones, thereby managing complexity through functional segmentation
Data Source
AI summary
The present application discloses a touch display panel including a first substrate, a liquid crystal, and a second substrate, wherein the first substrate is located on a light-exiting side of the touch display panel. The first substrate includes a first underlayer, a touch structure layer, a thin film transistor layer, and a pixel electrode layer. The touch structure layer and the thin film transistor layer are disposed on a side of the first underlayer close to the liquid crystal, and the pixel electrode layer is disposed on the thin film transistor layer. The touch structure layer includes a touch electrode, which is multiplexed as a common electrode.