Photomask Segmentation for Liquid Crystal Display Exposure Uniformity
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Solution Overview
Problem
Conventional liquid crystal display devices face issues with display unevenness and joint line visibility due to momentary power interruptions during scanning exposure, particularly at the overlapping exposure regions of large substrates, leading to defective products with visible mask traces and reduced yield.
Innovation Solution
The exposure apparatus incorporates a photomask design with first and second regions, where the second region has smaller, discretely dispersed transparent portions to minimize joint line visibility, even during temporary scanning stops, by arranging these portions vertically and orthogonally to the scanning direction, ensuring balanced aperture ratios and symmetrical patterns to prevent display unevenness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If scanning exposure is used for large substrates, then exposure area is improved, but joint line visibility worsens due to momentary power interruptions
Solution Approach 1:
The photomask is divided into multiple transparent portions (first transparent portions and second transparent portions) arranged in different regions. The second transparent portions are smaller and discretely dispersed to create multiple smaller exposure zones within the overlapping region, which blurs the joint line and reduces visibility of display unevenness caused by power interruptions during scanning exposure of large substrates.
2Loss of energy
If scanning stops temporarily during exposure, then power saving is improved, but display unevenness worsens at overlapping regions
Solution Approach 1:
The photomask design applies different characteristics to different regions: the second region contains smaller, discretely dispersed transparent portions specifically in the overlapping exposure region, while the first region has larger transparent portions. This local differentiation ensures that even if scanning stops temporarily, the smaller portions in the second region prevent concentrated display unevenness and maintain overall exposure quality.
3Quantity of substance
If larger transparent portions are used, then aperture ratio is improved, but joint line visibility worsens
Solution Approach 1:
The photomask is divided into multiple transparent portions (first transparent portions and second transparent portions) arranged in different regions. The second transparent portions are smaller and discretely dispersed to create multiple smaller exposure zones within the overlapping region, which blurs the joint line and reduces visibility of display unevenness caused by power interruptions during scanning exposure of large substrates.
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 configuration effectively inhibits the visual recognition of display unevenness and mask traces at joint portions, enhancing the quality and yield of large liquid crystal display devices by maintaining uniform exposure across the substrate, even during power interruptions.
Implementation Method 1
a photomask having a first region, and a second region adjacent to the first region in a vertical direction... the second region has a plurality of second transparent portions inside a second light-shielding portion
Implementation Method 2
in the photoalignment method, a photoalignment film is used as an alignment film, and by irradiating (exposing) the photoalignment film with light such as ultraviolet light, an alignment regulating force is generated in the alignment film and/or an alignment regulating direction of the alignment film is changed
Data Source
AI summary
This invention is an exposure apparatus for exposing a photoalignment film provided on a substrate. The exposure apparatus includes a light source and a photomask, and exposes the photoalignment film through the photomask while scanning the light source or the substrate. When a direction in which the light source or the substrate is scanned is taken as a scanning direction, and a direction that is orthogonal to the scanning direction is taken as a vertical direction, the photomask includes a first region and a second region that is adjacent to the first region in the vertical direction. The first region includes a plurality of first transparent portions inside a first light-shielding portion. The plurality of first transparent portions are arranged in the vertical direction. The second region includes a plurality of second transparent portions inside a second light-shielding portion.