OLED Duty Driving With Extended First On-Time to Reduce Flicker
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Solution Overview
Problem
In duty driving of light emitting display devices, anode charging is delayed during low luminance, leading to improper light emission at the initial duty cycle of a frame, resulting in noticeable flicker when switching frames.
Innovation Solution
A display device with a light emitting diode and an emission control transistor that controls on and off operations, where the first duty cycle has a longer on-duty period than subsequent cycles, ensuring proper light emission and reducing luminance differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If duty driving is used to control light emitting diode emission, then energy efficiency and display control are improved, but anode charging is delayed at low luminance causing flicker
Solution Approach 1:
The patent applies dynamics by making the on-duty period variable rather than fixed. The first duty cycle has a longer on-duty period than subsequent duty cycles, allowing the display to adapt the emission duration dynamically based on the frame position and luminance requirements, thereby preventing anode charging delay and flicker while maintaining energy efficiency
Solution Approach 2:
The patent changes the parameter of on-duty period duration across different duty cycles. By setting the first duty cycle with a longer on-duty period and subsequent duty cycles with progressively shorter on-duty periods, the system adjusts the emission parameter to compensate for anode charging delays at low luminance levels, eliminating flicker without sacrificing energy efficiency
2Device complexity
If equal on-duty periods are used for all duty cycles, then device complexity is reduced, but large luminance difference occurs when switching frames causing flicker
Solution Approach 1:
The patent applies local quality by differentiating the on-duty period duration for different duty cycles within a frame. The first duty cycle receives a longer on-duty period while subsequent duty cycles have shorter periods, creating localized optimization at the frame transition point to prevent luminance discrepancies and flicker without significantly increasing overall control complexity
Data Source
AI summary
A display device includes a light emitting diode disposed in a pixel; and an emission control transistor disposed in the pixel, and controlling on and off of the light emitting diode according to an emission control signal for each frame, wherein the frame includes a first duty cycle to a K-th duty cycle each of which sets an on-duty period and an off-duty period, and wherein the on-duty period of the first duty cycle is longer than the on-duty period of each of the second to K-th duty cycles.