Wavy Microcup Partition Walls for Electrophoretic Display Moire Reduction
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Solution Overview
Problem
Traditional microcup designs in electrophoretic displays are prone to Moire patterns and visual defects due to regular patterns on the microcup film and TFT backplane, which are exacerbated by the use of color filters, and attempts to reduce Moire by rotating microcups increase processing costs and reduce cutting yield.
Innovation Solution
The design features microcups with wavy partition walls that vary in pitch and amplitude, with at least one set of partition walls being wavy, allowing for pseudo-randomization without altering the height, thereby minimizing Moire patterns and visual defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If microcups are designed with regular patterns (same size, shape, and arrangement), then manufacturing is simplified and cutting yield is improved, but Moire patterns and visual defects occur when laminated to TFT backplane
Solution Approach 1:
The patent applies asymmetry by introducing wavy partition walls with varying pitch and amplitude in different microcups. This creates irregular, non-repeating patterns that break the symmetry causing Moire effects, while still maintaining manufacturability through a single embossing process that forms all microcups simultaneously
Solution Approach 2:
The patent implements local quality by allowing different microcups to have different wavy partition wall characteristics (different pitch and amplitude values). This local variation randomizes the overall pattern to eliminate Moire effects while maintaining consistent manufacturing parameters across the entire display surface
2Object-affected harmful factors
If microcups are rotated to reduce Moire phenomenon, then Moire pattern is reduced, but cutting yield decreases and processing cost increases
Solution Approach 1:
The patent applies preliminary action by pre-randomizing the microcup patterns through wavy partition walls during the manufacturing process itself. This eliminates the need for post-manufacturing rotation operations, thereby maintaining high cutting yield while effectively reducing Moire patterns
Solution Approach 2:
The patent extracts the rotation operation from the manufacturing process entirely. By incorporating randomness directly into the microcup structure through wavy partition walls, the harmful Moire effect is addressed without requiring the separate rotation step that would reduce productivity
3Illumination intensity
If color filter is utilized to improve display quality, then display performance is enhanced, but Moire pattern becomes more severe
Solution Approach 1:
The patent converts the potential harm of combining color filters with microcup patterns into a benefit by using wavy partition walls. The irregular patterns actually enhance display quality while the varying pitch and amplitude create sufficient randomness to prevent Moire effects, even when color filters are present
Data Source
Figure 1(a)~1(b)
Figure 2
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AI summary
The present invention is directed to an electrophoretic display film comprising: a) microcups each having a first shape, and b) remaining microcups which take up at least 10% of the total number of microcups and have shapes different from the first shape. The microcup designs of the present invention not only may reduce the Moiré pattern, but it may also make the defects of the microcup walls much less noticeable, and therefore increase the cutting yield.