LCD Alignment Film Exposure Segmentation
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Solution Overview
Problem
High-definition liquid crystal display panels, such as 4K and 8K, face issues with decreased transmittance due to increased wirings and switching elements, leading to higher power consumption and production throughput reduction, along with challenges in aligning substrates accurately to prevent display defects.
Innovation Solution
A liquid crystal display device with a reduced number of alignment exposures, using optical alignment films with specific pre-tilt angles and polymer compositions on substrates, where one alignment film is dividedly exposed and the other is not, to align liquid crystal molecules in four regions with orientations differing by integral multiples of 90 degrees, improving alignment accuracy and reducing flicker.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If four division alignment exposures are performed for each substrate to realize four division alignment within one pixel, then alignment precision is improved, but productivity deteriorates due to reduced throughput in production
Solution Approach 1:
The alignment process is segmented into two distinct approaches: one substrate undergoes four division alignment exposures while the other substrate uses a single full-surface exposure. This segmentation allows the system to achieve four-domain alignment precision without requiring all substrates to undergo the complex multi-exposure process, thereby maintaining productivity.
Solution Approach 2:
The patent combines the four division alignment exposures on one substrate with a single full-surface exposure on the other substrate. By merging these different exposure strategies, the system achieves the desired four-domain alignment effect while significantly reducing the total number of exposure operations required, thus improving throughput.
2Manufacturing precision
If boundary lines of division alignment exposure are caused to coincide between TFT substrate and facing substrate, then alignment precision is improved, but device complexity increases due to positioning accuracy requirements and thermal expansion distortion
Solution Approach 1:
The patent extracts the complex boundary alignment requirement from the manufacturing process by performing four division alignment exposures on only one substrate rather than both. This eliminates the need to precisely match boundary lines between substrates, as the unexposed substrate does not have division boundaries that need to align, thereby reducing positioning accuracy requirements and device complexity.
3Productivity
If pre-tilt angle on one substrate side is set to less than 90 degrees and pre-tilt angle on the other substrate side is set to substantially 90 degrees, then productivity is improved by reducing number of exposures, but reliability deteriorates due to residual DC electric field and uneven impurity ion distribution causing flicker
Solution Approach 1:
The patent intentionally creates asymmetry in the exposure process by applying four division alignment exposures to one substrate while applying only a single full-surface exposure to the other substrate. This asymmetric approach reduces the total number of exposures required (improving productivity) while the specific exposure conditions are optimized to minimize residual DC electric fields and impurity ion unevenness (maintaining reliability).
Solution Approach 2:
The patent changes the exposure parameters (number of exposures, exposure pattern) differently for the two substrates. By optimizing these parameters - using four divisions on one substrate and one full exposure on the other - the system achieves the desired balance between productivity and reliability, preventing flicker while reducing total exposure operations.
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 solution results in improved production throughput, reduced flicker, and excellent display quality by minimizing alignment exposures and asymmetrical electrical characteristics, while maintaining high transmittance and efficiency.
Implementation Method 1
at least one of the first alignment film and the second alignment film is an optical alignment film
Implementation Method 2
the optical alignment film is formed using a polymer having an optical alignment group in a side chain
Data Source
AI summary
This liquid crystal display device has a plurality of pixels. Each pixel in the plurality of pixels includes first to fourth alignment regions; these first to fourth alignment regions are arranged in the longitudinal direction of the pixels, and the difference between any two alignment orientations in the first to fourth alignment regions is approximately equal to an integer multiple of 90 degrees. Of the pre-tilt angles defined by a first alignment film and a second alignment film in each of the first to fourth alignment regions, one pre-tilt angle is less than 90 degrees and the other pre-tilt angle is substantially 90 degrees. The optical alignment film is formed using a polymer having an optical alignment group in the side chain, and the content of the optical alignment group in the side chain of the polymer is less than 1.1 mmol/g.