OLED Luminance Degradation Compensation via Dynamic Target Adjustment
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Solution Overview
Problem
Existing organic light emitting displays face issues with luminance uniformity and increased power consumption due to OLED degradation, leading to image sticking and compensation errors as the degradation progresses, with current compensation methods setting targets based on ideal, undegraded OLED luminance.
Innovation Solution
An organic light emitting display system that includes a degradation sensing circuit to calculate an average degradation value and a compensation target adjustor that stepwise adjusts the compensation target based on this value, reducing power consumption and minimizing compensation errors by dynamically adjusting the luminance compensation in the display panel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a uniform programming current is applied to sense the threshold voltage of OLEDs and adjust video data based on the sensed threshold voltage, then luminance compensation is achieved, but power consumption increases as OLED degradation deepens
Solution Approach 1:
The patent makes the compensation target dynamic by adjusting it according to the average degradation value. Instead of using a fixed ideal luminance target, the system dynamically modifies the compensation target to match the current average degradation level, thereby reducing the luminance gap and minimizing required power consumption while maintaining effective compensation
Solution Approach 2:
The patent changes the parameter of compensation target based on degradation level. By calculating the average degradation value from threshold voltages and adjusting the compensation target accordingly, the system adapts the compensation parameters to match current OLED conditions, reducing power consumption while maintaining compensation effectiveness
2Reliability
If the compensation target is set to ideal luminance of undegraded OLED, then luminance compensation is performed, but compensation error increases as usage time passes
Solution Approach 1:
The patent changes the compensation target parameter from fixed ideal luminance to a dynamic value that adapts to degradation. By calculating average degradation value and adjusting the compensation target accordingly, the system maintains accurate compensation without increasing error, even as OLEDs age
Solution Approach 2:
The patent implements feedback by sensing threshold voltages of OLEDs, calculating average degradation value, and using this information to adjust the compensation target. This closed-loop feedback mechanism ensures the compensation target remains accurate despite degradation, minimizing compensation errors
3Device complexity
If a fixed compensation target is used for all degradation levels, then compensation process is simple, but luminance gap between compensation target and degraded pixels increases
Solution Approach 1:
The patent introduces dynamics to the compensation target by making it adjustable based on degradation level. The system calculates average degradation from threshold voltages and modifies the compensation target accordingly, maintaining luminance uniformity without excessive complexity
Solution Approach 2:
The patent applies local quality by tailoring the compensation target to match the specific degradation level of the display. Instead of using a universal fixed target, the system adjusts the target locally according to the measured average degradation, ensuring optimal compensation for the current state
Data Source
AI summary
An organic light emitting display can include a display panel including pixels, a degradation sensing circuit to sense a threshold voltage of organic light emitting diodes (OLEDs) in the pixels and calculate an average degradation value based on the sensed threshold voltage of the OLEDs, a compensation target adjustor to adjust a compensation target based on the average degradation value, when the average degradation value is reduced by a previously determined reference value, and a data modulator to add and subtract a luminance compensation value determined depending on the adjusted compensation target to and from input digital video data and modulate the input digital video data. Also, each time the average degradation value is reduced by the previously determined reference value, the compensation target adjustor reduces stepwise the compensation target in conformity with changes in the average degradation value, and a stepwise adjustment width of the compensation target is non-uniform.