Pixel Electrode Opening Reduces LCD Mura
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Solution Overview
Problem
Conventional liquid crystal display (LCD) panels using polymer stabilized alignment (PSA) technology face issues with display mura due to alignment slits having non-identical widths, resulting from the photolithography process, which affects the brightness and quality of the display.
Innovation Solution
A pixel structure design with a middle portion of the pixel electrode having a second opening to expose the first opening in the upper electrode pattern, allowing for specific pre-tilt angles of liquid crystal molecules during the curing process, thereby reducing the area occupied by alignment slits and minimizing display mura.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If more alignment slits are formed in the pixel electrode to improve liquid crystal molecule alignment accuracy, then alignment precision is improved, but display mura increases due to non-identical slit widths from photolithography process variations
Solution Approach 1:
The patent extracts the alignment function from the pixel electrode by introducing a separate alignment layer with alignment slits. This alignment layer is positioned between the pixel electrode and the liquid crystal layer, allowing the pixel electrode to maintain its electrical function while the alignment layer provides the necessary alignment guidance. The alignment slits in this separate layer are designed to be substantially equal in width, eliminating the mura problem while maintaining alignment accuracy.
Solution Approach 2:
The patent segments the alignment function from the pixel electrode structure. Instead of forming alignment slits directly in the pixel electrode, the alignment layer is introduced as a distinct component. This segmentation allows independent optimization of the alignment layer's slit geometry (substantially equal widths) while the pixel electrode focuses on electrical functionality, thereby resolving the contradiction between alignment precision and display uniformity.
2Manufacturing precision
If alignment slits occupy more area of the pixel electrode to improve alignment accuracy, then alignment precision is improved, but the area available for other pixel electrode functions is reduced
Solution Approach 1:
The alignment function is extracted from the pixel electrode and implemented in a separate alignment layer. This allows the pixel electrode to dedicate its entire area to electrical functionality without compromising alignment accuracy, as the alignment layer's slits provide the necessary alignment guidance independently.
Solution Approach 2:
By segmenting the alignment function into a separate alignment layer, the pixel electrode's area is preserved for electrical functions. The alignment layer can be optimized for alignment performance with substantially equal width slits, while the pixel electrode maintains its full functional area without reduction.
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 design effectively reduces display mura caused by non-identical alignment slit widths, maintaining accurate liquid crystal alignment and improving display quality while minimizing the area occupied by alignment slits.
Implementation Method 1
the mixed liquid crystal material is heated to an isotropy state on a heater. Then, when the liquid crystal mixture is cooled to the ambient temperature of 25° C., the liquid crystal mixture returns to a nematic state
Implementation Method 2
the high molecular monomers are bonded to form a polymer layer by means of UV curing or heating, so as to realize the stabilized alignment
Data Source
AI summary
A pixel structure including a substrate, a scan line, a data line, an active device, a capacitor electrode line, an upper electrode pattern and a pixel electrode is described. The scan line and the data line are disposed on the substrate. The active device is electrically connected to the scan line and the data line. The capacitor electrode is disposed on the substrate. The upper electrode pattern is disposed above the capacitor electrode line, and the upper electrode pattern has a first opening therein to expose the capacitor electrode pattern. The pixel electrode is electrically connected with the active device and covers the capacitor electrode line and the upper electrode pattern, wherein the pixel electrode has a middle portion and a plurality of branches connecting to the middle portion, and the middle portion has a second opening therein to expose the first opening.