In-Cell Touch Display Data Line Reduction via Zigzag TFT Layout
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Solution Overview
Problem
In-cell type display devices require additional processes to form separate touch sensing lines, increasing fabrication costs and time due to the need for detailed additional processes and a higher number of mask processes.
Innovation Solution
A display device with a built-in touch screen is designed where thin film transistors (TFTs) are arranged in a zigzag form alongside data lines, and the pixel electrode and touch sensing line are formed simultaneously with the gate electrode and data line, respectively, reducing the number of data lines and mask processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate touch sensing lines are formed in in-cell type display devices, then touch sensing functionality is achieved, but the number of mask processes and fabrication steps increases
Solution Approach 1:
The patent merges the touch sensing line formation process with the data line formation process. The same data lines serve dual purposes: driving the display and sensing touch input. This is achieved by forming both the data lines and touch sensing lines simultaneously using the same mask process, eliminating the need for separate touch sensing line formation steps while maintaining effective capacitive touch sensing functionality.
Solution Approach 2:
The data lines are designed to perform multiple functions: they serve as both display driving lines and touch sensing electrodes. By making the data lines multi-functional, the patent eliminates the need for dedicated separate touch sensing lines, thereby reducing the number of mask processes from 6 to 4 while maintaining complete touch sensing coverage across the display panel.
2Reliability
If separate touch sensing lines are formed, then touch sensing is enabled, but fabrication time and cost increase
Solution Approach 1:
The patent combines the formation of data lines and touch sensing lines into a single simultaneous process step. Both line types are created using the same mask alignment and deposition processes, reducing the total number of fabrication steps. This merging of processes directly reduces fabrication time and associated costs while ensuring both display and touch functions are fully operational.
3Device complexity
If TFTs are arranged in zigzag form alongside data lines, then the number of data lines is reduced, but the arrangement complexity increases
Solution Approach 1:
The patent employs an asymmetric zigzag arrangement of TFTs along the data lines rather than a symmetric grid pattern. This asymmetric positioning allows for optimized spacing and reduced data line count while maintaining proper electrical connections and display performance. The zigzag pattern creates an irregular but functional layout that reduces the total number of data lines required.
Solution Approach 2:
The patent transitions from a conventional two-dimensional grid arrangement of TFTs to a zigzag pattern that effectively utilizes space in a different dimensional configuration. This dimensional reorganization allows TFTs to be positioned more efficiently along the data lines, reducing the number of data lines needed while maintaining all necessary pixel connections and display functionality.
Data Source
AI summary
Disclosed is a display device with a built-in touch screen. The display device includes a gate electrode and a pixel electrode on a substrate, an activation layer and a sensing contact portion, a source electrode and a drain electrode, and a gate insulation layer provided between the gate electrode and the activation layer and between the pixel electrode and the sensing contact portion. Thereby, it is possible to reduce the number of data lines arranged in the display panel. Also disclosed is a method of fabricating a display device with a built-in touch screen. The method includes forming a first gate electrode and a pixel electrode according to a first mask process, and forming an activation layer, a source electrode, a drain electrode, and a touch sensing line according to a second mask process. Thereby, it is possible to reduce the number of mask processes.