Luminance Correction for OLED Displays
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Solution Overview
Problem
Conventional luminance correction methods for organic light emitting displays fail to accurately correct luminance and color coordinates across all gray levels, leading to pronounced color deviations, especially at low gray levels, due to variations in manufacturing processes and differences in organic material efficiency between colors.
Innovation Solution
A luminance correcting system that sets a reference offset value for the gamma voltage of a reference gray level and detects differences in offset values between colors, applying additional offset values to specific gray levels to correct gamma voltage, thereby preventing color coordinate twisting and reducing pronounced color hues at low gray levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If luminance correction is performed only on reference gray level with direct offset application to remaining gray levels, then correction close to target value is achieved on reference gray level, but difference between luminance and color coordinates and target value increases in remaining gray levels, especially at gray levels further from reference gray level
Solution Approach 1:
The patent divides the gray levels into multiple segments (reference gray level and remaining gray levels) and applies different correction strategies to each segment. For reference gray level, direct offset application is used; for remaining gray levels, especially those further from reference, additional offset values are introduced to maintain correction accuracy across all segments.
Solution Approach 2:
The patent applies local quality by detecting differences in offset values for different colors (red, green, blue) and applying color-specific additional offset values where needed. This ensures that each color channel receives appropriate correction tailored to its specific characteristics at different gray levels, preventing color distortion while maintaining luminance accuracy.
2Device complexity
If offset values are directly applied to remaining gray levels without detecting color differences, then correction process is simple, but specific colors (reddish, greenish, bluish hues) become pronounced in gray levels further from reference gray levels
Solution Approach 1:
The patent implements feedback by detecting the actual offset values for each color at the reference gray level and using this information to determine whether additional offset values are needed for remaining gray levels. The controller compares detected offset differences against predetermined thresholds to dynamically decide on correction strategy, preventing color distortion while avoiding unnecessary complexity when simple direct application suffices.
3Ease of manufacture
If uniform offset values are applied to all colors, then correction process is straightforward, but variations in organic material efficiency among differently colored pixels cause white balance deterioration
Solution Approach 1:
The patent applies local quality by detecting differences in offset values for different colors (red, green, blue) at the reference gray level and applying color-specific additional offset values where needed. This ensures that each color channel receives appropriate correction tailored to its specific characteristics, maintaining white balance while correcting luminance variations caused by different organic material efficiencies.
Data Source
AI summary
A luminance correcting system for an organic light emitting display includes an image analyzing unit for analyzing an image on a display unit and for measuring luminance and color coordinates of reference gray level data, a reference offset value setting unit for setting reference offset values of respective color data in the reference gray level data to correspond to an image analysis result obtained by the image analyzing unit, a controller for detecting a difference in reference offset values of at least two color data among the respective color data in the reference gray level data and for comparing the difference with a reference value, and an additional offset value setting unit for setting an additional offset value corresponding to at least one gray level among gray level data excluding the reference gray level data when the difference in the reference offset values is not less than the reference value.