Photo-Alignment Control for LCD Polarization Accuracy
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Solution Overview
Problem
The existing photo-alignment processes in liquid crystal display manufacturing face challenges in achieving consistent polarization angle accuracy due to variations in the polarization axis of polarized light, primarily influenced by the positioning accuracy of the polarizing illumination device and the motion stage, which affects the alignment film's orientation consistency.
Innovation Solution
A photo-alignment control method that involves selecting discrete sampling locations and detection points on the substrate, measuring polarization angle deviations and illumination intensity levels, and calculating weighted dynamic polarization angle deviations to adjust the rotation of a rotary table, ensuring consistent polarization angle across the substrate surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the photo-alignment process uses a polarizing illumination device and motion stage to achieve high pixel density and display contrast, then the display quality is improved, but the polarization angle consistency deteriorates due to positioning accuracy variations
Solution Approach 1:
The patent performs preliminary measurement of polarization angle deviations at multiple discrete sampling locations across the substrate surface before the actual photo-alignment process. Based on these measurements, the system pre-calculates and stores correction values for the rotary table. During subsequent photo-alignment operations, these pre-computed correction values are applied to compensate for polarization angle variations, thereby maintaining consistent alignment angles without requiring real-time measurements.
Solution Approach 2:
The patent changes the parameter being controlled from the polarization angle of the illumination device to the rotation angle of the rotary table. By measuring polarization angle deviations at various sampling locations and converting these deviations into corresponding rotary table correction angles, the system compensates for illumination device variations through mechanical rotation adjustments, achieving consistent alignment angles across the entire substrate surface.
2Manufacturing precision
If the polarizing illumination device and motion stage positioning is simplified, then the device complexity is reduced, but the photo-alignment accuracy deteriorates
Solution Approach 1:
The system performs self-characterization by automatically measuring its own polarization angle deviations at multiple sampling locations and generating correction values without requiring external calibration equipment or complex manual adjustment mechanisms. The rotary table correction mechanism uses these self-generated correction values to compensate for positioning variations, enabling the system to maintain high photo-alignment accuracy through autonomous error compensation rather than complex external control systems.
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 method enhances the accuracy of the photo-alignment process by comprehensively monitoring and adjusting the yaw angles of the motion stage and polarizing illumination device, resulting in improved alignment angle consistency and positioning accuracy throughout the entire substrate surface.
Implementation Method 1
polarized light of a specified wavelength is irradiated onto the alignment film to trigger a photo-reaction, such as photo-crosslinking, photo-decomposition or photo-isomerization in the alignment film
Data Source
AI summary
A photo-alignment control method and a photo-alignment apparatus are disclosed. In the photo-alignment control method, a yaw angle of a motion stage (130) relative to a polarizing illumination device (110) is detected to derive a weighted dynamic polarization angle deviation of a substrate (200), so that a rotational angle of a rotary table (120) for rotating a substrate (200) is controlled, thereby effectively improving a control accuracy of a polarization angle in the photo-alignment process and further to ensure an accuracy of an alignment angle formed in an alignment film.