TFT Pixel Structure Laser Repair Diode Formation
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Solution Overview
Problem
Conventional laser repairing methods for white defects in TFT-LCD panels either result in permanent dark points or flickering gray defects, degrading display quality.
Innovation Solution
A pixel structure with a semiconductor electrode partially overlapped with a floating metal, where the data line and drain electrode have protruded regions, allowing a laser beam to form a diode structure that rectifies the electrical voltage, ensuring the white defect displays as a stable white or black point without flickering.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional laser repairing is used to connect drain electrode and scan line, then white defect is repaired, but pixel displays as permanent dark point in white-picture inspection
Solution Approach 1:
The patent introduces a floating metal layer as an intermediary component between the data line and drain electrode. This floating metal serves as a mediator that, when connected to the data line via laser repair, creates a diode structure. The diode structure allows current to flow in only one direction, preventing the pixel from displaying as a permanent dark point while still repairing the white defect. The floating metal layer acts as the crucial intermediary element that enables the rectified effect.
Solution Approach 2:
The patent changes the electrical parameters of the pixel by forming a diode structure through selective laser connection. By connecting the floating metal to the data line rather than directly connecting drain to scan line, the electrical characteristics are modified to create rectified effect. This parameter change ensures that the voltage difference conditions are met for the diode to function, allowing the pixel to display correctly in both white and black picture inspections.
2Reliability
If floating metal is connected to data line to form diode structure, then white defect displays as stable white or black point, but requires precise laser irradiation of protruded region
Solution Approach 1:
The patent applies preliminary action by pre-designing the data line with a protruded region that extends toward the floating metal. This protrusion is created during the manufacturing process before laser repair. The protruded region serves as a pre-positioned target that guides the laser beam to the exact location where connection is needed, reducing the precision requirement during the laser repair process. The preliminary structural preparation makes the subsequent repair operation more forgiving and easier to execute.
3Reliability
If larger voltage difference is applied to ensure rectified effect, then diode function is improved, but risk of damaging other components increases
Solution Approach 1:
The patent applies local quality by creating a specific structural configuration where the floating metal partially overlaps with both the data line and drain electrode. This localized overlapping structure concentrates the electrical connection at specific points (the protruded regions). The local quality of this overlapping structure ensures that the rectified effect is achieved at the intended location while the rest of the pixel structure remains unaffected. The selective connection at specific locations allows for controlled voltage application without damaging other components.
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 enhances repair yield and quality by maintaining display integrity in both white-picture and black-picture inspections, eliminating the issues of permanent dark points or flickering defects.
Implementation Method 1
a laser beam is used to irradiate the protruded region of the data line from the lower surface side of the substrate to electrically connect the data line and the floating metal
Data Source
AI summary
The pixel structure and the repairing method of the TFT array substrate are provided. The pixel has a semiconductor electrode which is partially overlapped with a floating metal located in the first conductive layer. Both the data line and the drain electrode have protruded regions partially overlapped with the semiconductor electrode and the floating metal. Once the pixel is found to be a white defect, a laser beam is used to irradiate the protruded region of the data line to electrically connect the data line and the floating metal and so as to form a diode structure having the rectified effect. Consequently, after the laser repair, the pixel defect will display as the non-flicked white point and black point in the white-picture inspection and the black-picture inspection respectively.