Active Matrix Substrate Redundant TFT Repair
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Solution Overview
Problem
Conventional LCD panel manufacturing processes often result in defects, such as bright dot defects, which are difficult to repair using existing laser cutting or welding methods, leading to increased production costs and reduced yield rates.
Innovation Solution
An active matrix substrate with redundant active devices, where a second TFT is electrically isolated from the pixel electrode, allowing it to substitute a damaged first TFT, enabling effective repair through laser cutting and welding processes to prevent bright dot defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of repair
If laser cutting or welding is used for defect repair, then some defects can be repaired, but not all defects can be repaired and some even cannot be repaired
Solution Approach 1:
The pixel unit is segmented into multiple active devices (first active device and second active device) instead of using a single TFT. This segmentation allows the second active device to serve as a redundant component that can be activated when the first active device is defective, thereby expanding the repair capability to handle various defect types including those that cannot be repaired by conventional laser methods alone.
Solution Approach 2:
The second active device is pre-configured and electrically isolated during manufacturing, ready to be activated when needed. The repair method involves cutting the connection of the defective first active device and reconnecting the pixel electrode to the second active device through laser welding, which is a preliminary prepared solution that can be rapidly deployed without requiring complex redesign or additional components.
2Ease of manufacture
If conventional pixel structure design is used, then manufacturing is simple, but not all defects can be rapidly repaired
Solution Approach 1:
The patent merges the conventional simple pixel structure with a redundant active device structure. The second active device is integrated into the same pixel unit with shared electrodes (gate electrode connected to scan line, source electrode connected to data line), maintaining the simplicity of conventional manufacturing while adding repair capability. The merged structure allows rapid laser-based repair by simply switching electrical connections rather than requiring complex multi-step repair processes.
3Reliability
If redundant active devices are added to pixel units, then defect repair capability is improved, but device complexity increases
Solution Approach 1:
The second active device is designed with universal connectivity to the same scan line and data line as the first active device, allowing it to function as a drop-in replacement. This multi-functionality approach means the redundant device uses the same electrical infrastructure and control signals, minimizing the increase in structural complexity while maximizing repair capability. The universal design allows the same repair process to work for any defective active device in the pixel unit.
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
The use of redundant active devices in the active matrix substrate allows for successful repair of pixel units, enhancing the yield rate of LCD panels by preventing bright dot defects and ensuring normal operation, while being compatible with conventional manufacturing processes.
Implementation Method 1
a second metal layer is formed by a laser welding process
Implementation Method 2
the metal materials are heated and melted by the laser beam to join the two metal materials together
Implementation Method 3
a photoresist layer is heated and evaporated by a laser beam to remove the photoresist layer
Implementation Method 4
the photoresist layer is heated and evaporated by a laser beam to remove the photoresist layer
Data Source
AI summary
An active matrix substrate including a substrate, a plurality of scan lines, a plurality of data lines and a plurality of pixel units is provide. All of the scan lines, the data lines, the pixel units are disposed on the substrate. Each of the pixel units is electrically connected with the corresponding scan line and data line. In addition, at least a part of the pixel units further includes a plurality of active units and a pixel electrode. The active devices are respectively electrically connected with the corresponding scan lines and data lines and the pixel unit is electrically connected with one of the active devices. In summary, each of the pixel units of the active matrix substrate provided by the invention includes more than one active device. When an active device is damaged under normal operation, another active device may be employed for repairing the pixel unit.