TFT Substrate Repair Pattern for LCD Bright-Spot Defect
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Solution Overview
Problem
In liquid crystal displays (LCDs), repairing bright-spot defects using protrusion patterns increases additional capacitance, leading to delayed gate signals and deteriorated image quality due to the formation of additional capacitance between pixel electrodes and gate lines.
Innovation Solution
A thin-film transistor (TFT) substrate design featuring a repair pattern that is either spaced apart or partially connected to the pixel electrode, with connection or separation patterns that reduce additional capacitance by controlling the overlap width and arrangement, thereby minimizing capacitance increase during repair.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protrusion pattern is formed to overlap a preceding gate line to repair bright-spot defects, then the defect can be repaired by forming a short circuit between the pixel electrode and the gate line, but additional capacitance is created between the pixel electrode and the gate line, which increases the gate load and delays the gate signal
Solution Approach 1:
The protrusion pattern is divided into multiple segments (first protrusion pattern and second protrusion pattern) separated by a gap. This segmentation reduces the overlapping area with the gate line, thereby reducing additional capacitance while still enabling defect repair through selective laser irradiation on the segments
Solution Approach 2:
The protrusion pattern has different properties in different regions: it overlaps the gate line in some areas (to enable repair) but is separated in other areas (to reduce capacitance). The pattern width and gap size are locally optimized to balance repair effectiveness with capacitance reduction
2Ease of manufacture
If a protrusion pattern of predetermined size is formed to repair bright-spot defects, then the repair process can be standardized, but the additional capacitance increases the overall capacitance of each pixel and deteriorates image quality
Solution Approach 1:
The width of the protrusion pattern and the size of the gap between segments are carefully controlled within specific ranges. By optimizing these parameters, the additional capacitance is minimized while maintaining the standardized repair process, thus preserving image quality
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 solution effectively reduces additional capacitance, preventing signal delays and maintaining image quality by strategically designing the repair pattern to overlap or separate from the gate lines, thus allowing for efficient repair of bright-spot defects without compromising the LCD's performance.
Implementation Method 1
melting the repair pattern with the laser beam to form a melted repair pattern
Implementation Method 2
irradiating a laser beam onto the repair pattern to form a hole in the gate insulating film and the passivation layer directly under the repair pattern
Data Source
AI summary
A thin-film transistor substrate includes; gate lines which extend in a first direction, the gate lines including a first gate line and a second gate line, the first gate line disposed adjacent to and previous to the second gate line, data lines which are insulated from the gate lines and extend in a second direction perpendicular to the first direction, a pixel electrode formed in a region where the first gate line and the second gate lines cross the data lines and connected to the second gate line, and a repair pattern which at least partially overlaps the first gate line, the repair pattern comprising a plurality of connection patterns, wherein the connection patterns extend from the pixel electrode in the second direction toward the first gate line, have a predetermined width measured in the first direction, and are arranged at predetermined intervals along the first direction.