Filled-Up Trench Structure for Transreflective LCD Light Leakage
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Solution Overview
Problem
Conventional multi-domain vertical alignment (MVA) LCDs experience light leakage in the dark state due to irregular alignment of liquid crystal molecules, which decreases the contrast ratio.
Innovation Solution
A transreflective LCD with a filled-up trench structure is implemented, featuring a conformal transparent electrode within trenches on either the color filter or TFT array plates, which twists the electrical field and regularizes the alignment of liquid crystal molecules, thereby achieving multi-domain vertical alignment and reducing light leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If protrusions or slits are used on the inner surfaces of transparent substrates to deviate alignment direction, then view angle is increased, but light leakage occurs in the dark state and contrast ratio decreases
Solution Approach 1:
The invention divides the single alignment direction into multiple domains by creating protrusions that segment the liquid crystal layer into different alignment regions. Each domain has its own alignment direction, and the combination of multiple domains achieves wide view angle while maintaining dark state performance through the filled-up trench structure that prevents irregular alignment at domain boundaries.
Solution Approach 2:
The protrusions are strategically positioned in specific local regions to create domain boundaries, while the filled-up trench structure provides localized control over liquid crystal alignment at these boundaries. This local quality approach allows different regions to have different alignment characteristics, achieving both wide view angle and reduced light leakage.
2Adaptability or versatility
If protrusions are used to achieve multi-domain vertical alignment, then view angle is improved, but alignment irregularity causes light leakage
Solution Approach 1:
The alignment layers are pre-formed on the inner surfaces of the transparent substrates before the liquid crystal is introduced. These alignment layers are positioned on the protrusions to predetermined orientations, ensuring that the liquid crystal molecules align regularly along the protrusions in advance, thereby achieving precise multi-domain vertical alignment and preventing light leakage.
Solution Approach 2:
Alignment layers serve as intermediaries between the protrusions and the liquid crystal molecules. These alignment layers are formed on the protrusions and guide the liquid crystal molecules to align in specific directions, ensuring regular alignment and preventing the irregular alignment that causes light leakage while maintaining multi-domain vertical alignment capabilities.
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 filled-up trench structure effectively addresses light leakage in the dark state by ensuring regular alignment of liquid crystal molecules, enhancing the contrast ratio and maintaining wide view angles.
Implementation Method 1
the transparent electrode can twist the electrical field in the liquid crystal layer after applying a voltage on the transparent electrode to achieve the result of multi-domain vertical alignment
Implementation Method 2
the alignment of the liquid crystal molecules can be more regular to solve the problem of light leakage in the dark state
Data Source
AI summary
A transreflective LCD has a TFT array plate, a color filter plate and a liquid crystal therebetween. A trench is in the overcoat layer of the TFT array plate and/or the color filter plate. The trench can be located in a transmission area or in a reflective area of a pixel. A conformal transparent electrode is located therein, and an overcoat material is filled up in the trench.