Touch Display Device Reducing Parasitic Capacitance
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Solution Overview
Problem
The existing touch display devices experience deteriorated touch performance due to increased parasitic capacitance between touch lines and touch electrodes, which is caused by their overlapping structure, leading to RC delay and reduced sensitivity.
Innovation Solution
The touch display device reduces parasitic capacitance by employing a mesh-shaped touch electrode structure with redundant electrodes that are electrically connected to touch lines, minimizing the overlapping area between touch lines and touch electrodes in non-contact areas, and using a redundant electrode system to reduce parasitic capacitance and internal resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If touch lines are disposed to overlap touch electrodes in non-contact areas, then the touch display device can be manufactured with standard processes, but parasitic capacitance is increased causing RC delay and deteriorated touch performance
Solution Approach 1:
The touch electrode is divided into a first touch electrode and a second touch electrode that are disposed at different layers. The first touch electrode is in the same layer as the touch line, while the second touch electrode is in a different layer. This segmentation allows the touch lines to overlap the first touch electrode without creating parasitic capacitance issues, while the second touch electrode provides the necessary sensing function, thus resolving the contradiction between manufacturability and touch performance.
Solution Approach 2:
The patent introduces a vertical dimension by stacking the first and second touch electrodes at different layers. This multi-layer configuration allows the touch lines to pass through or overlap one electrode layer without creating harmful parasitic capacitance, while maintaining effective contact with the other electrode layer for touch sensing, thereby solving the RC delay problem while preserving touch functionality.
2Reliability
If the overlapping area between touch lines and touch electrodes is reduced, then parasitic capacitance and RC delay are reduced improving touch sensitivity, but the structural complexity increases
Solution Approach 1:
The touch electrode is segmented into two parts at different layers: the first touch electrode that minimizes overlapping with touch lines, and the second touch electrode that compensates for the reduced overlapping area. This segmentation allows the system to achieve low parasitic capacitance while maintaining sufficient electrode area for sensitive touch detection.
Solution Approach 2:
The first and second touch electrodes are electrically connected and function together as a unified touch sensing element. By merging their functions, the system achieves both low parasitic capacitance (through minimized overlapping of the first electrode) and high touch sensitivity (through the combined area of both electrodes).
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 enhances touch sensitivity and performance by reducing RC delay and parasitic capacitance, improving the accuracy and speed of touch signals, while also providing redundancy in case of touch line breakage to enhance yield.
Implementation Method 1
parasitic capacitance formed between the touch lines and the touch electrodes is increased, whereby RC delay is increased
Data Source
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AI summary
A touch display device includes a unit pixel disposed on a substrate (101), the unit pixel comprising a plurality of subpixels (SP); a light-emitting element (120) disposed at each of the plurality of subpixels (SP); an encapsulation unit (140) disposed on the light-emitting element (120); a plurality of touch electrodes (150) disposed on the encapsulation unit (140); a touch line connected to each of the plurality of touch electrodes (150), the touch line extending through the touch electrode (150); and at least one redundant electrode (160) spaced apart from the touch electrode (150), the at least one redundant electrode (160) being independently disposed in each of the plurality of touch electrodes (150), the at least one redundant electrode (160) being disposed in the unit pixel. The at least one redundant electrode (160) is disposed along the touch line, whereby it is possible to reduce parasitic capacitance formed between the touch line and the touch electrode (150).