LCD Dummy Pad Asymmetry for Cell Gap Uniformity
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Solution Overview
Problem
Conventional liquid crystal displays (LCDs) experience spot generation due to brightness differences in regions where dummy pads and second pads are formed, caused by non-uniformities in their heights during substrate attachment.
Innovation Solution
The LCD design includes symmetrical dummy pads on the lower substrate, not electrically connected to the integrated circuit, to maintain a uniform cell gap between substrates, preventing brightness differences and spot generation by positioning them diagonally opposite the second pads and ensuring they are symmetrical with respect to a line dividing the substrate into upper and lower portions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If dummy pads are formed adjacent to second pads on the lower substrate, then the cell gap is maintained, but brightness difference and spots are generated due to non-uniform heights
Solution Approach 1:
The patent applies asymmetry by positioning dummy pads at specific locations (first and second upper sides of the lower substrate) rather than symmetrically across all sides. This asymmetric placement targets the specific area where brightness non-uniformity occurs, maintaining cell gap uniformity in critical regions while avoiding unnecessary dummy pads in other areas.
Solution Approach 2:
The patent implements local quality by placing dummy pads only in specific locations (first and second upper sides) where brightness non-uniformity is detected, rather than uniformly across the entire substrate. This localized approach maintains cell gap uniformity in critical regions while minimizing the overall impact on display uniformity.
2Ease of manufacture
If dummy pads are positioned to maintain cell gap, then substrate attachment is facilitated, but brightness differences occur in regions where dummy pads are formed
Solution Approach 1:
The patent uses asymmetric positioning of dummy pads (first and second upper sides only) to maintain cell gap uniformity in critical attachment regions while avoiding the formation of brightness differences in other areas. This asymmetric configuration allows easy substrate attachment while preserving display uniformity.
Solution Approach 2:
The patent creates dummy pads that are symmetrical to the second pads with respect to a line of symmetry, effectively copying the second pad configuration in the upper region. This copying approach ensures uniform cell gap maintenance while the symmetrical design helps compensate for brightness non-uniformity.
3Illumination intensity
If dummy pads are made symmetrical to second pads, then brightness difference is reduced, but device complexity increases
Solution Approach 1:
The patent applies asymmetry by limiting dummy pad placement to only the first and second upper sides of the lower substrate, rather than creating a fully symmetrical configuration across all sides. This asymmetric approach reduces the number of dummy pads required while still maintaining brightness uniformity in critical regions.
Solution Approach 2:
The patent implements local quality by placing dummy pads only in specific locations where brightness non-uniformity is detected, rather than creating a comprehensive symmetrical pattern throughout the entire substrate. This localized placement reduces device complexity while maintaining display uniformity.
Data Source
AI summary
A liquid crystal display (LCD) capable of preventing spots from being generated by difference in brightness caused by variation in a gap between substrates is provided. The LCD includes a first pad unit positioned on an upper corner of a lower substrate, a second pad unit positioned on a lower corner of the lower substrate diagonally across from the first pad unit, an integrated circuit electrically connected to the first pad unit and the second pad unit, and dummy pads positioned on the other upper corner of the lower substrate. The dummy pads are substantially symmetrical with second pads included in the second pad unit thus helping maintain the gap between the substrates uniform.