Touch Display Edge Area CD Compensation for Parasitic Capacitance
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Solution Overview
Problem
The curvature of touch display devices in the edge area leads to a decrease in touch sensitivity due to undesirable parasitic capacitance, which affects the accuracy of touch detection and input.
Innovation Solution
The implementation of a critical dimension (CD) compensation area in the edge region of the display panel, where the critical dimension of touch electrode metals increases as distance from the inner area increases, helps maintain a constant step between the touch electrode metals and the lower electrode layer, reducing parasitic capacitance and enhancing touch sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If the display panel uses a curved edge area design, then the aesthetic appearance and design flexibility are improved, but the step between touch electrode metals and lower electrode layer decreases, causing increased parasitic capacitance and reduced touch sensitivity
Solution Approach 1:
The patent applies different critical dimensions to touch electrode metals in different regions. Specifically, touch electrode metals in the edge area have a larger critical dimension than those in the inner area, creating local variation in electrode size to compensate for the curved surface effect and maintain consistent parasitic capacitance characteristics across the display panel.
Solution Approach 2:
The patent changes the critical dimension parameter of touch electrode metals based on their location. By increasing the critical dimension in the edge area compared to the inner area, the patent adjusts the electrode geometry parameter to offset the reduced step height caused by curvature, thereby maintaining uniform touch sensing performance.
2Reliability
If the critical dimension of touch electrode metals is increased in the edge area, then parasitic capacitance is reduced and touch sensitivity is improved, but the manufacturing precision requirements increase
Solution Approach 1:
Instead of uniformly increasing the critical dimension across the entire display panel, the patent applies this adjustment locally only to the edge area. This targeted approach improves touch sensitivity where needed while minimizing the overall impact on manufacturing precision requirements compared to a universal change.
Solution Approach 2:
The patent segments the display panel into inner area and edge area regions, applying different critical dimension specifications to each. This segmentation allows for optimized electrode dimensions in the edge area without compromising the manufacturing simplicity of the inner area, thereby balancing performance improvement with manufacturability.
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 effectively improves touch sensitivity and accuracy by compensating for the capacitance changes in the edge area, allowing for better detection of touch presence and location, thereby enhancing the overall performance of touch display devices.
Implementation Method 1
capacitance-based touch sensing method is widely used for detecting presence or absence of touch and touch coordinates based on a change in capacitance formed on a plurality of touch electrodes on a display panel
Implementation Method 2
there is a problem that decreases the touch sensitivity due to an undesirable parasitic capacitance
Data Source
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AI summary
Present disclosure provides a touch display device comprising a display panel including an inner area forming a first step between a first touch electrode metal with first critical dimension and a lower electrode layer, and an edge area having at least one of CD compensation area, which is located outside of the inner area, forming a second step between a second touch electrode metal with second critical dimension larger than the first critical dimension and the lower electrode layer; and a touch circuit for sensing touch presence or touch location by using a touch sensing signal received from the touch electrode metals.