Liquid Crystal Display Panel with Optical Mask for Pretilt Control
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Solution Overview
Problem
Liquid crystal display panels face issues with reduced aperture ratio and light transmittance due to Domain Boundary Texture (DBT) and Fringe Field Texture (FFT), which are caused by misalignment of liquid crystal molecules, leading to decreased viewing angles and contrast ratios, and the photo-alignment process struggles with maintaining uniform pretilt angles.
Innovation Solution
An optical mask is used to control the pretilt angles in different regions of the liquid crystal display panel by varying the intensity and direction of polarized ultraviolet light irradiation, allowing for distinct pretilt angles in domain boundary regions and normal-luminance regions, thereby reducing the area of DBT and FFT.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a photo-alignment process is used to form pretilt without physical rubbing, then manufacturing yield is improved by avoiding foreign substance introduction, but maintaining uniform pretilt angles across different regions becomes difficult
Solution Approach 1:
The patent applies different pretilt angles to different regions of the alignment film - a first pretilt angle to a first region and a second pretilt angle to a second region. This local differentiation allows optimization of liquid crystal molecule alignment in specific areas, particularly at domain boundaries, while maintaining overall manufacturing precision through controlled photo-alignment processes.
2Adaptability or versatility
If liquid crystal molecules are tilted in different directions to improve viewing angle, then viewing angle characteristics are enhanced, but domain boundary textures form reducing aperture ratio
Solution Approach 1:
The patent implements different pretilt angles in different regions to control liquid crystal molecule orientation. By applying a first pretilt angle in a first region and a second pretilt angle in a second region, the patent optimizes molecular alignment to reduce domain boundary textures and maximize aperture ratio while maintaining wide viewing angle characteristics.
Solution Approach 2:
The patent changes the pretilt angle parameter across different regions of the alignment film. By varying this critical parameter spatially, the patent controls the tilt direction of liquid crystal molecules to minimize domain boundary effects and maximize light transmission, thereby improving aperture ratio while preserving viewing angle performance.
3Ease of manufacture
If rubbing cloth method is used to form pretilt, then alignment film pretilt is formed easily, but foreign substance introduction and static electricity reduce yield
Solution Approach 1:
The patent replaces the mechanical rubbing cloth method with a photo-alignment process that uses polarized ultraviolet light to form pretilt. This substitution eliminates mechanical contact that causes foreign substance introduction and static electricity, thereby maintaining ease of pretilt formation while significantly improving manufacturing yield and reliability.
Solution Approach 2:
The patent changes the method of pretilt formation from mechanical rubbing to photo-alignment using polarized UV light. This parameter change in the alignment process eliminates the harmful effects of foreign substance introduction and static electricity associated with mechanical rubbing, while still achieving effective pretilt formation for liquid crystal molecule alignment.
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 approach enhances the aperture ratio and light transmittance of the liquid crystal display panel, improving viewing angles and contrast ratios while minimizing black afterimages and power consumption.
Implementation Method 1
The photo-alignment process forms a pretilt of an alignment film using a non-contact method without forming patterns, slits or projections in a pixel region. The photo-alignment process includes applying a photo-reactive material onto a substrate and obliquely irradiating ultraviolet (UV) light to the surface on which the photo-reactive material is applied.
Data Source
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AI summary
A liquid crystal display panel, including a unit pixel including a first substrate (100) having a first alignment film (130), a second substrate (200) having a second alignment film (230) spaced apart from and facing the first alignment film, and a liquid crystal layer interposed between the first alignment film and the second alignment film; and first and second adjacent domains (610,620), each of which includes a domain boundary region (616,626), and a normal-luminance region (614,624) adjacent to the domain boundary region, wherein pretilt angles of liquid crystal molecules (LLC) near the first alignment film in the domain boundary regions are greater than pretilt angles of liquid crystal molecules near the first alignment film in the normal-luminance regions.