Micro-LED Subpixel Repair Using Color Conversion and Defect Mapping
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Solution Overview
Problem
Micro LED displays face defects such as open/short issues, transfer/integration/bonding defects, and substrate driver pixel defects, leading to yield reduction and increased costs when using spare micro devices for repair.
Innovation Solution
The implementation of defect mapping and color conversion techniques, where spare sub-pixels are used to replace defective ones by matching their color emission, and spatial variation in sub-pixel positions to minimize visual artifacts, allowing for efficient repair of micro LED displays without significantly increasing material costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If spare micro devices are used to replace defective sub-pixels, then yield is improved, but material costs increase
Solution Approach 1:
The patent changes the emission wavelength parameter of existing sub-pixels through color conversion materials (phosphors or quantum dots) to make them suitable for replacing defective sub-pixels of different colors. Instead of using additional spare micro devices, the system converts the wavelength characteristics of available sub-pixels to match the required color, thereby reducing material costs while maintaining yield.
Solution Approach 2:
The patent makes sub-pixels universal by enabling them to serve multiple color functions through color conversion. A single sub-pixel structure can be converted to emit different wavelengths depending on the phosphor or quantum dot material applied, allowing one sub-pixel to replace defective sub-pixels of various colors without requiring separate spare devices for each color.
2Manufacturing precision
If color conversion materials are applied to sub-pixels, then color matching for repair is improved, but manufacturing complexity increases
Solution Approach 1:
The patent applies color conversion materials during the initial micro-LED fabrication process rather than after transfer to the display substrate. This preliminary action ensures precise color matching before the sub-pixels are deployed, and the materials are applied in the controlled environment of the LED manufacturing process where precision is easier to maintain.
Solution Approach 2:
The patent uses photolithography and other standard semiconductor copying techniques to apply color conversion materials with high precision. The materials are deposited in precise patterns corresponding to the sub-pixel locations, ensuring accurate color matching without requiring complex manual alignment processes.
3Object-affected harmful factors
If sub-pixel positions are varied spatially, then visual artifacts are reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent introduces controlled asymmetric variations in sub-pixel positions, specifically varying the spacing between sub-pixels in different directions. By making the spacing asymmetric rather than uniform, the system reduces the visibility of periodic patterns and visual artifacts that would otherwise appear in the display, while the variations are small enough to remain within manufacturing capabilities.
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 yield of micro LED displays by effectively replacing defective sub-pixels with spare ones, maintaining image quality while reducing material costs through efficient defect mapping and color conversion methods.
Implementation Method 1
applying a color conversion material to at least one of the primary sub-pixels to convert the low-wavelength emission into a different emission wavelength from the low-wavelength emission
Implementation Method 2
applying a color filter material to at least one of the primary sub-pixels to convert the combined-wavelength emission into a different emission wavelength
Data Source
AI summary
What disclosed are structures and methods for repairing emissive display systems. Various repairing techniques embodiments in accordance with the structures and methods are provided to conquer and mitigate the defected pixels and to increase the yield and reduce the cost of emissive displays systems.