Color Filter Edge Orientation for Display Substrate Alignment
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Solution Overview
Problem
Transparent display devices face issues with light transmittance and color reproducibility due to non-uniform color filter coverage, leading to light leakage and reduced contrast ratios, caused by height differences and alignment force variations at the color filter boundaries.
Innovation Solution
A display substrate design with a color filter that overlaps only a portion of each pixel area, featuring edges parallel to the alignment direction of the alignment layer, reducing height differences and maintaining uniform alignment force, thereby preventing light leakage and improving display quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a partial-cover color filter is used to increase light transmittance, then light transmittance is improved, but alignment force uniformity deteriorates due to height differences at color filter boundaries
Solution Approach 1:
The color filter is designed with different edge configurations for different boundaries. The first edge is parallel to the alignment direction while the second edge is perpendicular, creating different local geometries at different boundaries. This local differentiation allows the color filter to maintain uniform alignment force at critical boundaries while still providing partial coverage for high transmittance.
Solution Approach 2:
The color filter employs asymmetric edge designs where the first edge parallel to the alignment direction prevents alignment force deterioration, while the second perpendicular edge accepts some alignment force variation. This asymmetric configuration optimizes the balance between maintaining alignment uniformity and achieving partial coverage for high light transmittance.
2Manufacturing precision
If a full-cover color filter is used to improve color reproducibility, then color reproducibility is improved, but light transmittance deteriorates
Solution Approach 1:
Instead of applying full coverage, the color filter is strategically applied to only portions of the pixel area where color definition is most critical. This partial coverage approach maintains adequate color reproducibility while leaving other areas transparent to maximize light transmittance, achieving an optimal balance between the two competing requirements.
3Ease of manufacture
If the color filter edge is perpendicular to the alignment direction, then manufacturing simplicity is improved, but alignment force deteriorates causing light leakage
Solution Approach 1:
Different edges of the color filter are assigned different functional qualities based on their orientation. The first edge parallel to the alignment direction is designed to maintain alignment force and prevent light leakage, while the second perpendicular edge is optimized for manufacturing simplicity. This local quality differentiation resolves the contradiction between ease of manufacture and alignment reliability.
Data Source
AI summary
A display substrate for a display device includes: a substrate which includes a light blocking region defining a plurality of pixel areas disposed in a matrix, each pixel area having a length extending in a second direction, and a width extending in a first direction; a color filter overlapping a portion of the each pixel area of the plurality of pixel areas; and an alignment layer disposed on the color filter. the color filter includes a first edge parallel to the second direction, and a second edge forming a predetermined angle with the first edge. The second edge is substantially parallel to an alignment direction of the alignment layer.