Pixel Greyscale Compensation for AMOLED Uniformity Correction
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Solution Overview
Problem
Modern display technologies, particularly active matrix organic light emitting diode (AMOLED) devices, suffer from significant luminance non-uniformity due to factors like TFT threshold variation, OLED voltage and luminance variation, manufacturing tolerances, voltage drop, and contamination, leading to perceivable luminosity or color variations across images.
Innovation Solution
A method is developed to measure and compensate for pixel non-uniformity by selecting greyscale drive levels, determining offset values to create a uniform flat field, and using these measurements to generate a uniformity correction function that adjusts input drive levels for each pixel, applicable to both initial and ongoing display corrections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If individual pixel measurements and compensation are implemented, then display uniformity is improved, but device complexity and processing requirements increase
Solution Approach 1:
The patent applies preliminary action by measuring and determining offset values for each pixel during the manufacturing process before the display is deployed. A uniformity correction function is pre-calculated and stored in memory based on these measurements, allowing the display to compensate for non-uniformity without requiring complex real-time calculations during operation. This resolves the contradiction by achieving high display uniformity through advance preparation rather than complex ongoing processing.
2Measurement precision
If multiple greyscale drive levels are measured to create accurate uniformity correction function, then compensation accuracy is improved, but measurement time and processing complexity increase
Solution Approach 1:
The patent applies the skipping principle by selecting a limited number of significant greyscale drive levels (e.g., 2-5 levels) that represent the most critical portions of the usable greyscale range, rather than measuring all possible greyscale levels. This allows the uniformity correction function to be accurately determined with minimal measurement time, resolving the contradiction between compensation accuracy and measurement time by focusing measurements only where they matter most.
3Manufacturing precision
If offset values are determined iteratively to create uniform flat field, then uniformity correction accuracy is improved, but processing time and computational complexity increase
Solution Approach 1:
The patent applies preliminary action by performing iterative offset value determination during the manufacturing process when the display is being set up, not during actual operation. The uniformity correction function including offset values is calculated in advance and stored in memory. This resolves the contradiction by allowing time-consuming iterative processing to occur during manufacturing rather than during use, achieving high uniformity correction accuracy without impacting operational processing time.
Data Source
AI summary
What is disclosed are methods of non-uniformity compensation for active matrix light emitting diode device (AMOLED) and other emissive displays. For each pixel, greyscale level offsets for a number of predetermined greyscale drive levels which produce a uniform flat field are determined and used to generate a correction function for the pixel.