In-Cell Touch Array Substrate Dummy Lead Parasitic Capacitance Compensation
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Solution Overview
Problem
In-cell touch panels experience display grayscale differences between pixel units with and without touch leads due to varying parasitic capacitance, leading to uniformity issues and display defects under the same data voltage.
Innovation Solution
The implementation of an array substrate with self-capacitance electrodes connected via touch leads and dummy leads, where dummy leads are used to input a common voltage signal, ensuring that both types of pixel units are affected by the same parasitic capacitance, and the touch leads are designed with multiple layers to reduce resistance and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If touch leads are used to connect self-capacitance electrodes in pixel units, then touch functionality is achieved, but display grayscale uniformity deteriorates due to varying parasitic capacitance between pixel units with and without touch leads
Solution Approach 1:
The patent creates dummy leads that are identical in structure and electrical characteristics to the touch leads, but positioned in pixel units without touch functionality. These dummy leads replicate the parasitic capacitance effects of real touch leads, allowing pixel units with and without touch leads to have matched electrical characteristics. This copying approach resolves the grayscale uniformity issue by ensuring all pixel units experience equivalent parasitic capacitance regardless of whether they contain functional touch leads.
2Manufacturing precision
If dummy leads are added to pixel units without touch leads, then display grayscale uniformity is improved, but device complexity increases due to additional lead structures
Solution Approach 1:
The patent merges the formation of touch leads and dummy leads into a single manufacturing process step. Both types of leads are created using the same fabrication techniques and material deposition processes, eliminating the need for separate manufacturing sequences. This merging approach reduces overall manufacturing complexity while maintaining the functional distinction between touch leads (connected to self-capacitance electrodes) and dummy leads (not connected to self-capacitance electrodes).
Solution Approach 2:
The lead structure design serves multiple functions: functional leads provide touch signal transmission while dummy leads provide parasitic capacitance compensation. Both lead types share the same structural characteristics and manufacturing processes, allowing a single lead fabrication system to produce both varieties. This multi-functionality reduces the need for specialized equipment or processes, thereby reducing device complexity despite the addition of dummy leads.
3Reliability
If touch leads are arranged within different columns of pixel units, then touch sensitivity is improved, but display uniformity deteriorates due to non-uniform lead distribution
Solution Approach 1:
The patent employs asymmetric distribution of touch leads within pixel unit columns while compensating through symmetric dummy lead placement. Touch leads are strategically positioned in specific columns to optimize touch detection sensitivity, creating an asymmetric functional layout. Dummy leads are then distributed in a complementary asymmetric pattern that balances the overall electrical characteristics across the display. This controlled asymmetry allows the system to achieve both high touch sensitivity and display uniformity by optimizing the spatial arrangement of different lead types.
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 solution reduces display grayscale differences and improves display uniformity by ensuring that all pixel units, regardless of having touch leads or not, are affected equally by parasitic capacitance, while also optimizing power consumption and manufacturing simplicity.
Implementation Method 1
display grayscale differences between pixel units provided with touch leads and those provided with no touch leads under the control of a same data voltage
Data Source
AI summary
An array substrate, a manufacturing method thereof, and a touch display device are provided in the embodiments of the present invention. The array substrate includes: a common electrode layer including a plurality of self-capacitance electrodes distributed in an array; a drive circuit; and a plurality of pixel units distributed in an array. N self-capacitance electrodes located in a same column constitute an electrode column, each electrode column corresponding to M columns of pixel units. The N self-capacitance electrodes located in the same column are connected with the drive circuit via N touch leads arranged within different columns of pixel units. Among the M columns of pixel units, M−N columns of pixel units provided with no touch leads are provided with dummy leads connected with the drive circuit, and the drive circuit is used to input a common voltage signal into the dummy leads and the touch leads.