OLED Display Gamma Calculation Using Single Test Image
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Solution Overview
Problem
The manufacturing process of organic light emitting diode (OLED) display devices becomes longer and more complex due to the need for capturing multiple test images at different gray levels for each color to set unique RGB gamma values for each display area, which is not feasible for mass production.
Innovation Solution
A method to calculate RGB gamma values for OLED display panels by displaying a single test image at a target gray level, measuring luminance values, and using predetermined RGB gray level-driving current curves to derive target gamma values for each display area, allowing for distinct gamma settings without requiring multiple test images.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple test images at different gray levels are captured for each color to set unique RGB gamma values for each display area, then the luminance accuracy and color consistency are improved, but the manufacturing process time and complexity increase
Solution Approach 1:
The patent applies preliminary action by pre-storing the relationship between gray levels and driving currents in lookup tables (LUTs) before the actual gamma calculation process. This allows the system to quickly retrieve and compare driving current values without performing complex calculations during manufacturing, significantly reducing the time required while maintaining the ability to calculate accurate gamma values for each display area
Solution Approach 2:
The patent uses copying by measuring the luminance of a single test image and using that measurement to derive gamma values for multiple gray levels through the pre-stored LUT relationships. Instead of capturing multiple test images, the system copies the luminance measurement data and processes it through different gray level mappings to obtain comprehensive gamma correction parameters
2Manufacturing precision
If multiple test images at different gray levels are captured for each color to set unique RGB gamma values for each display area, then the color consistency across display areas is improved, but the manufacturing process complexity increases
Solution Approach 1:
The patent applies parameter changes by transforming the problem from measuring multiple physical test images to manipulating digital parameters (gray level values and driving current relationships) stored in LUTs. The system changes the gray level parameters in the LUTs to correspond to different target gray levels, allowing gamma calculation for multiple conditions from a single physical measurement
Solution Approach 2:
The patent introduces an intermediary mechanism in the form of lookup tables that store the relationship between gray levels and driving currents. This intermediary LUT structure mediates between the single test image measurement and the multiple gamma values needed, eliminating the need for complex multi-image capture and processing while maintaining color consistency
3Productivity
If a single test image is used to calculate gamma values for each display area, then the manufacturing process time is reduced, but the ability to accurately determine gamma values for different gray levels may be compromised
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing driving current relationships for multiple gray levels in lookup tables before the manufacturing measurement process. This allows the system to derive accurate gamma values for different gray levels from a single test image measurement, maintaining measurement precision while improving productivity
Solution Approach 2:
The patent applies segmentation by separating the gamma calculation process into distinct segments corresponding to different gray levels. Each gray level has its own entry in the LUT with specific driving current relationships, allowing the system to calculate separate gamma values for each gray level segment from a single unified measurement, ensuring accuracy across the full gray level range
Data Source
AI summary
A method of calculating a gamma-value for a display panel includes displaying a first color test image having a first target gray-level and then measuring a first luminance-value implemented by at least one first color-pixel included in a jth display-area, displaying a second color test image having the first target gray-level and then measuring a second luminance-value implemented by at least one second color-pixel included in the jth display-area, deriving an estimated driving current flowing in the second color-pixel at the first target gray-level based on RGB gray level-driving current curves, deriving a second target gray-level when the estimated driving current flows in the first color-pixel based on the RGB gray level-driving current curves, and calculating a target gamma-value to be applied to the first color-pixel included in the jth display-area based on the first target gray-level, the second target gray-level, the first luminance-value, and the second luminance-value.