OLED Pixel Luminance Correction for Degradation Uniformity
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Solution Overview
Problem
Display devices with organic EL elements experience unevenness due to individual differences in stress properties of the elements, leading to misregistration and degradation of light-emitting layers, which affects the luminance and white balance of the display.
Innovation Solution
A display device driving method that calculates cumulative stress for each pixel, determines an efficiency residual ratio based on correlation data, and corrects luminance signals to compensate for degradation, using correction circuits to ensure uniform luminance across the display panel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a reference current is used to calculate cumulative stress for all pixels, then the calculation process is simplified, but display unevenness occurs due to individual differences in stress properties of organic EL elements
Solution Approach 1:
The patent applies local quality by assigning individual correlation data to each pixel based on its specific stress properties. Instead of using a universal reference current for all pixels, the system selects correlation data that matches the actual stress characteristics of each pixel, allowing localized adjustment that accounts for individual differences in organic EL elements while maintaining overall system functionality.
2Manufacturing precision
If individual correlation data is selected for each pixel based on stress properties, then display uniformity is improved, but the device complexity and data management burden increase
Solution Approach 1:
The patent manages complexity by parameterizing the selection process. Correlation data is organized according to stress property parameters, and the selection is based on comparing actual stress properties against these parameters. This systematic approach to parameter management allows individualized correction without requiring complex ad-hoc processing for each pixel.
3Speed
If cumulative stress is calculated using reference current for all pixels, then processing speed is maintained, but accuracy in determining degradation degree decreases due to individual element variations
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing correlation data that represents stress properties under various conditions. This allows the system to quickly retrieve and apply appropriate correlation data without performing complex real-time calculations, thereby maintaining processing speed while improving the accuracy of degradation degree determination through individualized correlation.
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
The method reduces display unevenness by accurately accounting for individual element degradation, maintaining consistent luminance and white balance despite variations in organic EL element properties.
Implementation Method 1
Display devices including organic EL (electroluminescent) elements in a matrix are adopted in display panels
Data Source
AI summary
A display device driving method of driving a display device that includes a display panel including plural pixels, the display device driving method including: calculating, for each of the plural pixels, cumulative stress that is an accumulation of stress corresponding to an output luminance of the pixel; selecting, based on a selection signal input to the display device, one correlation data item from among a plurality of correlation data items each corresponding to a different one of the plural pixels and indicating a relationship between the cumulative stress and an efficiency residual ratio that indicates a degradation degree of the pixel; determining the efficiency residual ratio, based on the one correlation data item and the cumulative stress; and correcting, for each of the plural pixels, a luminance signal corresponding to the pixel, based on the efficiency residual ratio that corresponds to the pixel and is determined in the determining.