LCD Drain Electrode Repair for IPS White Defect Control
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Solution Overview
Problem
In IPS LCD panels, incomplete removal of the ohmic contact layer during manufacturing leads to doped ions remaining on the semi-conductor layer, causing current leaks and preventing the drain electrode from maintaining a pre-set voltage, resulting in white defects due to altered grayscale values.
Innovation Solution
A method for repairing white defects in LCD panels involves using a laser to separate the drain electrode into two parts, forming insulating layers to prevent oxidation, and coupling the pixel electrode to the common electrode to ensure a voltage difference of 0V, effectively converting the white defect to a dark defect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the drain electrode is separated into two parts using a laser to fix the white defect, then the voltage maintenance is improved, but the electrode is exposed to air and oxidation occurs affecting display quality
Solution Approach 1:
The patent applies inert atmosphere by introducing a protective gas environment (nitrogen or argon) during the laser separation process. This inert gas displaces oxygen from the vicinity of the drain electrode, preventing oxidation of the exposed electrode surfaces while allowing the laser to effectively separate the electrode into two parts for voltage control.
Solution Approach 2:
The patent applies preliminary action by performing protective coating deposition on the drain electrode before laser separation. A thin insulating or protective layer is deposited in advance to shield the electrode from oxidation during subsequent processing steps, ensuring the electrode maintains its electrical properties after repair.
2Reliability
If the drain electrode is separated into two parts using a laser to fix the white defect, then the voltage control is improved, but the gate insulating layer is damaged causing oxidation of the gate electrode
Solution Approach 1:
The patent applies segmentation by dividing the laser processing into distinct stages: first separating the drain electrode with controlled energy parameters, then selectively repairing the gate insulating layer. This segmented approach allows precise control of the laser parameters to minimize damage to the gate insulating layer while achieving effective electrode separation.
Solution Approach 2:
The patent applies intermediary by introducing a protective sacrificial layer between the laser beam and the gate insulating layer. This intermediate layer absorbs excess laser energy and protects the gate insulating layer from direct laser damage, preventing oxidation of the gate electrode while still allowing effective separation of the drain electrode.
3Reliability
If the ohmic contact layer is completely removed during manufacturing, then the current leak is prevented, but the manufacturing precision requirement increases
Solution Approach 1:
The patent applies self-service by designing the ohmic contact layer with self-aligned features that enable automatic removal without requiring high-precision manual intervention. The layer incorporates specific material properties or structural features that allow it to be selectively removed through standard manufacturing processes, reducing the precision burden while ensuring complete removal to prevent current leaks.
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 method improves display quality by preventing oxidation of the drain and gate electrodes, ensuring accurate voltage maintenance, and effectively converting white defects to dark defects without compromising the design or affecting signal transmission.
Implementation Method 1
A method for repairing white defects in LCD panels involves using a laser to separate the drain electrode into two parts
Data Source
AI summary
A method for repairing a white defect of a LCD panel includes providing a substrate, the substrate defining pixel areas which themselves comprise a base, a first metal layer, a first insulating layer, a semi-conductor layer, an ohmic contact layer, a source electrode, a drain electrode, and a second insulating layer; forming a through hole by laser in the second insulating layer, the through hole extending through the second insulating layer and separating the drain electrode into two spaced parts; forming a third insulating layer to cover the first conductive layers, the second insulating layer and the though hole and forming a second conductive layer by laser on the third insulating layer to couple the first conductive layer to the second conductive layer.