OLED Pixel Circuit Reverse Bias Control for Drift Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In OLED displays, the driving transistor and OLED are often in a forward biased state for extended periods, leading to electric characteristic drifts and reduced service life, as well as decreased current efficiency.
Innovation Solution
A control method for a pixel circuit that includes a reverse bias time period during the non-display stage, where specific control signals are input to reverse bias both the light-emitting element and the driving transistor, utilizing a timing sequence that differs voltage levels at various input ends to achieve this reverse bias without additional devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the driving transistor and OLED are kept in forward biased state for extended periods to maintain display operation, then the display can continuously show images, but electric characteristic drifts occur and service life is shortened
Solution Approach 1:
The patent implements periodic reverse biasing during non-display stages (horizontal and vertical blanking periods) to counteract the continuous forward biasing during display operation. This periodic action allows electrons to be released from trapping centers at regular intervals, preventing cumulative electric characteristic drifts while maintaining continuous display capability.
Solution Approach 2:
The patent applies preliminary anti-action by introducing reverse biasing before significant electric characteristic drifts can occur. During non-display stages, the reverse bias voltage is applied to prevent electron accumulation in trapping centers before it leads to threshold voltage shifts and performance degradation, thereby extending device service life.
2Reliability
If reverse bias is applied to eliminate electric characteristic drifts and extend service life, then reliability improves, but additional control signals and voltage management complexity increase
Solution Approach 1:
The patent merges the reverse biasing function with existing non-display stages (horizontal and vertical blanking periods) of the OLED display timing structure. By combining the protective reverse bias action with already-present idle periods, the patent avoids adding separate dedicated reverse bias stages, thereby reducing overall system complexity while achieving reliability improvement.
Solution Approach 2:
The non-display stages serve multiple functions: they provide the necessary idle time for pixel circuit reset and simultaneously serve as the timing window for applying reverse bias to prevent electric characteristic drifts. This multi-functionality eliminates the need for separate reverse bias implementation, simplifying the control architecture.
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
This approach eliminates electric characteristic drifts, recovers current efficiency, and prolongs the service life of both the driving transistor and the OLED by reversing the bias during non-display stages.
Implementation Method 1
inputting, in the reverse bias time period, a first control signal to an input end of the pixel circuit to make both the light-emitting element and the driving transistor to be reverse biased
Data Source
AI summary
A control method for a pixel circuit, a control circuit for a pixel circuit and a display device are provided. A timing sequence of the pixel circuit includes a driving display stage and a non-display stage. The non-display stage includes a reverse bias time period. The control method includes: inputting, in the reverse bias time period, a first control signal to an input end of the pixel circuit to make both the light-emitting element and the driving transistor to be reverse biased.