Display Panel Driving Method for AOD Brightness Stability
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Solution Overview
Problem
In Always On Display (AOD) mode, display panels experience brightness degradation and flickering due to current leakage during the keeping phase of the data refresh cycle, where the driver transistor does not write new data voltage.
Innovation Solution
A method for driving a display panel in low-frequency mode, involving a light-emitting control signal with a duty cycle adjustment. The method includes providing a light-emitting control signal with an initial duty cycle during an active phase and performing at least one first switch and a second switch during the keeping phase, where the first switch is performed before the second switch, and the duty cycle is increased after the second switch, ensuring higher brightness during the first switch compared to the second switch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the display panel is refreshed at a low data refresh frequency to reduce power consumption, then power consumption is reduced, but brightness degradation and flickering occur due to current leakage during the keeping phase
Solution Approach 1:
The patent implements periodic brightness compensation by adjusting the light-emitting control signal duty cycle at specific intervals during the keeping phase. Multiple switches (first switch and second switch) are performed periodically to compensate for brightness degradation caused by current leakage, while maintaining the overall low refresh frequency for power savings.
Solution Approach 2:
The patent performs preliminary brightness compensation during the keeping phase before the panel brightness degrades to an unacceptable level. By proactively adjusting the duty cycle of the light-emitting control signal during the keeping phase, the system prevents noticeable flickering while maintaining low power consumption throughout the entire refresh cycle.
2Illumination intensity
If the duty cycle of the light-emitting control signal is adjusted to compensate for brightness degradation, then brightness stability is improved, but brightness fluctuations and flickering may become noticeable
Solution Approach 1:
The patent segments the brightness compensation process into multiple stages by performing separate first switch and second switch operations during the keeping phase. Each switch adjusts the duty cycle to a different level (a% for first switch, b% for second switch), allowing gradual compensation that minimizes visible flickering while maintaining brightness stability.
Solution Approach 2:
The patent dynamically adjusts the duty cycle of the light-emitting control signal based on the actual brightness degradation level during the keeping phase. The system adapts the compensation amount and timing of each switch operation to match the current brightness state, optimizing the balance between brightness stability and flickering reduction.
3Illumination intensity
If multiple switches are performed on the light-emitting control signal during the keeping phase, then brightness stability is improved, but the complexity of the driving control increases
Solution Approach 1:
The patent manages control complexity by systematically changing the duty cycle parameter at predetermined stages during the keeping phase. The first switch changes the duty cycle to a% and the second switch changes it to b%, with each change following a defined pattern that simplifies the control logic while achieving effective brightness compensation through multiple switches.
Data Source
AI summary
The method includes, in a low-frequency driving mode where a keeping phase is arranged between two active phases, providing a light-emitting control signal with a duty cycle of a % to a pixel circuit during the active phase; and performing first and second switches on the light-emitting control signal during the keeping phase. The first switch is performed before the second switch. Panel brightness at the first switch is higher than panel brightness at the second switch. The duty cycle of the light-emitting control signal is b % after the second switch. b>a. A total duration of active levels of the light-emitting control signal within one frame after the first switch is between a total duration of active levels of the light-emitting control signal with the duty cycle of a % and a total duration of active levels of the light-emitting control signal with the duty cycle of b % within one frame.