Photo Alignment Method for LCD Panels Using Masked Polarized Light
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Solution Overview
Problem
Liquid crystal display (LCD) panels face challenges in image display quality due to the slits and protrusions on electrodes, which affect the alignment of liquid crystal molecules, leading to decreased luminance and increased afterimages.
Innovation Solution
A photo alignment method involving a substrate and mask with a transmission and light blocking portion, where polymer chains are formed to align liquid crystal molecules in a direction parallel to the incident light, improving the alignment and concentration of liquid crystals in a matrix pattern, thereby enhancing response speed and light transmittance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If slits and protrusions are added to electrodes to change liquid crystal tilting direction, then viewing angle is increased, but luminance decreases
Solution Approach 1:
The pixel region is divided into multiple sub-regions (first, second, third, fourth sub-regions) with different alignment directions. This segmentation allows each sub-region to contribute differently to the overall display performance, achieving wide viewing angle through diversified alignment while maintaining luminance by avoiding uniform slit/protrusion structures that block light.
Solution Approach 2:
Different alignment directions are applied to different sub-regions within the pixel. The first and third sub-regions have alignment directions tilted toward the center from opposite sides, while the second and fourth sub-regions have opposite alignment directions. This local variation in alignment quality achieves wide viewing angle without the need for light-blocking slits and protrusions.
2Manufacturing precision
If slits and protrusions are used to align liquid crystal molecules, then alignment direction control is improved, but afterimages increase
Solution Approach 1:
The mechanical/physical structures of slits and protrusions are replaced with a photo-alignment method using polarized light. Light is irradiated from different directions to different sub-regions during the photo-alignment process, creating the desired alignment patterns without any physical obstructions that would cause afterimages.
Solution Approach 2:
The alignment directions are controlled by changing the irradiation direction of polarized light during photo-alignment, rather than using fixed geometric structures. By adjusting the light irradiation parameters (direction, polarization), precise alignment control is achieved without the harmful effects of slits and protrusions.
3Manufacturing precision
If light is irradiated in directions parallel to the interface between transmission and light blocking portions, then polymer chain alignment is improved, but manufacturing complexity increases
Solution Approach 1:
A sensor detects the actual position of the mask and substrate in real-time, and this position information is fed back to the control unit. The control unit adjusts the mask position based on the detected position data, ensuring that light is irradiated in the correct direction parallel to the interface between transmission and light blocking portions, thereby achieving precise polymer chain alignment despite manufacturing variations.
Solution Approach 2:
The mask position is made dynamically adjustable during the photo-alignment process. Instead of using a fixed mask, the system can change the mask position in real-time based on feedback, allowing adaptation to manufacturing tolerances and ensuring optimal alignment conditions are always met.
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 method improves image display quality by increasing response speed and light transmittance while reducing afterimages in LCD panels.
Implementation Method 1
Light is irradiated through the mask in a direction substantially parallel with an interface between a transmission portion and a light blocking portion of the mask. Polymer chains are formed on an upper portion of the organic layer. The polymer chains are aligned in an alignment direction toward an incident direction of the light.
Implementation Method 2
A photo alignment method involving a substrate and mask with a transmission and light blocking portion, where polymer chains are formed to align liquid crystal molecules in a direction parallel to the incident light
Data Source
AI summary
In a photo alignment method, a substrate and a mask are aligned so that the substrate is spaced apart from the mask by a predetermined gap. An organic layer is formed on the substrate. The mask has a transmission portion and a light blocking portion. Light is irradiated through the mask in a direction substantially parallel with an interface between the transmission portion and the light blocking portion of the mask. Polymer chains are formed on an upper portion of the organic layer. The polymer chains are aligned in an alignment direction toward an incident direction of the light. Locations of the substrate and the mask are sensed in real time. The mask is transported to a predetermined location with respect to the substrate based on the sensed locations of the substrate and the mask.