Luminance Correction for OLED Displays via Gamma Voltage Adjustment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Organic light emitting display devices face issues with luminance variations due to manufacturing dispersion and external DC-DC converter configurations, leading to impractical luminance correction and potential color coordinate distortion.
Innovation Solution
A luminance correction system that includes an image analyzing unit for measuring luminance and color coordinates, a main-gamma offset generating unit for setting offset values, a driving voltage sensing unit for detecting power signal changes, and a gamma voltage adjusting unit that applies these offsets to the data driver, minimizing luminance and color variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If DC-DC converters are mounted external to the display, then device complexity is reduced and ease of manufacture is improved, but power signal level variations occur among displays leading to luminance variations
Solution Approach 1:
The patent applies parameter changes by adjusting the gamma voltage based on the sensed power signal level. The system changes the gamma voltage parameter dynamically to compensate for variations in power signal levels caused by external DC-DC converters, thereby maintaining consistent luminance across different displays despite manufacturing variations in power supply voltage.
Solution Approach 2:
The patent implements feedback by using a power signal level sensing unit to detect the actual power signal level and feeding this information back to a gamma voltage adjusting unit. This closed-loop feedback mechanism allows the system to automatically compensate for power signal variations and maintain uniform luminance across displays manufactured with different external DC-DC converters.
2Manufacturing precision
If only luminance correction is applied, then luminance uniformity is improved, but white balance becomes distorted due to efficiency disparity among red, green, and blue pixels
Solution Approach 1:
The patent applies local quality by generating separate gamma offset values for each color (red, green, blue) based on their individual luminance characteristics. Instead of applying a uniform correction to all pixels, the system adjusts each color channel's gamma voltage independently according to its specific efficiency characteristics, thereby maintaining both luminance uniformity and correct white balance.
3Manufacturing precision
If gamma voltage is adjusted to correct luminance variations, then luminance uniformity is improved, but the system complexity increases due to additional sensing and adjustment units
Solution Approach 1:
The patent applies universality by designing a gamma voltage adjusting unit that handles multiple functions: it compensates for power signal level variations, corrects luminance non-uniformity, and maintains white balance across all color channels. This multi-functional approach consolidates what could be multiple separate correction systems into a single integrated unit, minimizing the increase in system complexity while achieving comprehensive luminance correction.
Data Source
AI summary
A luminance correction system for organic light emitting display devices is disclosed. In one aspect, an image displayed in a pixel unit of each of the display devices is analyzed and the luminance and color coordinate for main gray-level data is measured. A main-gamma offset value corresponding to the result of image analysis may be generated. A change in voltage of a driving power signal input from an external source of each of the display devices may be sensed. A sub-gamma offset value is generated by applying the change in voltage of the sensed driving power signal. A main-gamma voltage for the main gray level corresponding to the set main-gamma offset value and the set sub-gamma offset value is adjusted and output as an adjusted main-gamma voltage. The adjusted main-gamma voltage may be applied to a data driver of each of the display devices.