Multi-Mask Photo-Alignment for LCD Domain Formation
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Solution Overview
Problem
Current photo-alignment processes for liquid crystal displays (LCDs) face challenges in achieving wide viewing angles and efficient domain formation in pixels, particularly in vertical alignment (VA) mode LCDs, where existing methods struggle to uniformly control the alignment direction and pretilt angle of liquid crystal molecules across large display panels.
Innovation Solution
The use of two or more photo-masks with overlapping regions, where at least one transmission part includes a semi-transmission section, allows for varying light irradiation directions and intensities, enabling the formation of multiple domains with different alignment directions in a pixel by adjusting the transmittance of the semi-transmission sections to achieve uniform exposure and alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a single photo-mask is used for photo-alignment, then the device structure is simple, but the ability to form multiple domains with different alignment directions is insufficient
Solution Approach 1:
The photo-alignment process is segmented into multiple exposure steps using two separate photo-masks. The first photo-mask forms a first domain with a first alignment direction, and the second photo-mask forms a second domain with a second alignment direction. This segmentation allows each photo-mask to be optimized for specific alignment directions while collectively achieving multi-domain formation.
Solution Approach 2:
Two photo-masks are combined in sequence to achieve the function of forming multiple domains with different alignment directions. The first photo-mask and second photo-mask are applied to the same alignment layer, merging their effects to create a multi-domain liquid crystal display with enhanced viewing angle characteristics.
2Manufacturing precision
If photo-masks with overlapping regions are used, then uniform exposure and alignment are achieved, but the device complexity increases
Solution Approach 1:
The photo-masks are designed with different local characteristics: the first photo-mask has transmission parts optimized for forming domains in specific regions, while the second photo-mask has transmission parts optimized for other regions. The overlapping region contains transmission parts from both photo-masks that work together to achieve uniform exposure and alignment across the entire display panel.
3Productivity
If larger display panels are manufactured, then productivity increases, but boundary line defects and light irradiation defects increase
Solution Approach 1:
The overlapping region of the two photo-masks acts as an intermediary zone that mediates between different exposure regions. The transmission parts in the overlapping region ensure uniform light distribution and alignment, preventing boundary line defects that would otherwise occur at the edges of large display panels.
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 formation of multiple domains with different alignment directions in a pixel, improving the wide viewing angle capability and reducing manufacturing costs by allowing for larger display panels with reduced boundary line defects and defects in light irradiation regions.
Implementation Method 1
a photo-alignment method, which irradiates ultraviolet beams to an alignment layer including a photo-reactive material to control an alignment direction and an alignment angle of a liquid crystal molecule
Data Source
AI summary
The present invention is directed to an exposure apparatus and photo-mask, and method for manufacturing liquid crystal display using the same. An exposure apparatus according to an exemplary embodiment of the present invention provides an exposure apparatus which includes: a first photo-mask comprising a plurality of transmission parts; and a second photo-mask comprising a plurality of transmission parts, the first photo-mask and the second photo-mask comprising an overlapping region where the first photo-mask and the second photo-mask are partially overlapped, wherein at least one transmission part included in at least one of the first photo-mask and the second photo-mask in the overlapping region comprises a semi-transmission section, and a transmittance of the semi-transmission section is greater than or equal to 0% and less than 100%.