Display Panel Drain Electrode Bridge Removal
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Solution Overview
Problem
Conventional multi-domain PVA (MPVA) mode LCDs face etching defects and display malfunctions due to the narrow width requirements of bridge electrodes, which can be misaligned during manufacturing and damaged by spacers, limiting aperture ratio and yield.
Innovation Solution
The display panel directly connects the drain electrode of a thin film transistor to multiple sub-pixel electrodes within each domain without a bridge electrode, using contact holes to facilitate this connection and eliminate the need for a bridge electrode, thereby preventing etching defects and improving manufacturing yield.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a bridge electrode is used to connect sub-pixel electrodes, then the liquid crystal molecules can be controlled, but the bridge electrode width must be less than 6 μm which causes etching defects due to mask misalignment
Solution Approach 1:
The patent removes the bridge electrode from the structure entirely, extracting the problematic component that caused etching defects. The drain electrode is extended to directly contact the sub-pixel electrodes, eliminating the need for the separate bridge electrode that required precise etching with width less than 6 μm.
Solution Approach 2:
The patent merges the function of the drain electrode with the bridge electrode connection function. By extending the drain electrode to directly contact the sub-pixel electrodes, the separate bridge electrode component is eliminated, combining the electrical connection function into the existing drain electrode structure.
2Ease of manufacture
If a bridge electrode is used to connect sub-pixel electrodes, then the data voltage can be applied to sub-pixel electrodes, but the bridge electrode may be damaged when a spacer is disposed on it
Solution Approach 1:
The patent extracts and removes the bridge electrode from the structure, eliminating the component that is vulnerable to damage during spacer placement. The drain electrode extension directly contacts the sub-pixel electrodes without requiring a separate bridge electrode that could be damaged.
3Reliability
If the bridge electrode width is reduced to prevent liquid crystal malfunction, then the liquid crystal molecules can be controlled properly, but mask misalignment during etching causes defects
Solution Approach 1:
The patent removes the bridge electrode entirely, eliminating the component that requires narrow width control. This extraction resolves the contradiction by removing the source of both the liquid crystal control issue and the etching defect problem, thereby improving manufacturing yield.
Solution Approach 2:
Instead of reducing the bridge electrode width to control liquid crystal molecules, the patent inverts the approach by extending the drain electrode to directly contact the sub-pixel electrodes. This reversal eliminates the need for narrow-width etching while maintaining proper liquid crystal control.
Data Source
AI summary
A display panel includes a gate line dividing a pixel region into a first region and a second region and including a gate electrode, a data line crossing the gate line and including a source electrode, a thin film transistor connected to the gate line and the data line and including the gate electrode, the source electrode, and a drain electrode facing the source electrode, a protective layer disposed on the thin film transistor and comprising a first contact hole and a second contact hole, and first and second sub-pixel electrodes disposed on the first and second regions of the divided pixel region, respectively. The drain electrode is directly connected to the first sub-pixel electrode through the first contact hole, and the drain electrode is directly connected to the second sub-pixel electrode through the second contact hole.