OLED Pixel Circuit Reverse-Bias Initialization to Reduce Transistor Aging
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Rapid aging of the driving thin film transistor in organic light-emitting displays leads to reduced service life and increased power consumption, which affects the performance and longevity of OLEDs.
Innovation Solution
The display panel incorporates a pixel circuit with a specific configuration of transistors and a driving method that includes distinct scanning signals and light-emitting control signals to manage the initialization, storage, and light-emitting stages, ensuring that the organic light-emitting diode is reverse-biased during initialization and minimizing current flow through the transistors, thereby reducing power consumption and delaying transistor aging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the organic light-emitting diode is forward-biased during initialization, then the initialization is effective, but the driving thin film transistor ages rapidly and power consumption increases
Solution Approach 1:
The patent dynamically switches the biasing state of the OLED between forward-bias during light-emitting stage and reverse-bias during initialization stage. This is achieved by controlling the scanning signals and light-emitting control signals to differentially activate the fifth transistor (connected to power supply) and seventh transistor (connected to reference voltage), thereby adapting the circuit configuration to different operational phases and preventing rapid transistor aging during initialization.
2Productivity
If the driving thin film transistor operates continuously, then the display function is maintained, but power consumption increases and transistor aging accelerates
Solution Approach 1:
The patent implements periodic control of transistor operation by dividing the display cycle into distinct phases: initialization stage (where fifth transistor is off and seventh transistor is on, minimizing current) and light-emitting stage (where fifth transistor is on and seventh transistor is off, enabling normal operation). This periodic switching pattern maintains display functionality while reducing overall power consumption and preventing continuous stress on the driving transistor.
3Device complexity
If a simple pixel circuit configuration is used, then the device complexity is reduced, but the ability to control initialization and light-emitting stages separately is compromised
Solution Approach 1:
The patent segments the pixel circuit into functionally distinct transistor groups: the fifth transistor (T5) dedicated to power supply control during light-emitting stage, and the seventh transistor (T7) dedicated to reference voltage control during initialization stage. This segmentation allows independent control of initialization and light-emitting operations through separate scanning signals and light-emitting control signals, providing the necessary adaptability while maintaining a relatively simple overall circuit structure.
Data Source
AI summary
The present application provides a display panel and a driving method of a pixel circuit. The display panel includes a scan driver, a light-emitting control driver, a data driver, a plurality of pixel circuits, and a plurality of pixels each corresponding to one of the pixel circuits. Each of the pixel circuits includes a first transistor to a seventh transistor, a capacitor and an organic light-emitting diode. A control terminal of the fourth transistor is configured to input a first scanning signal; and a first electrode of the fourth transistor is connected to a second electrode of the third transistor, a control terminal of the first transistor and a terminal of the capacitor. Another terminal of the capacitor is connected to a first electrode of a fifth transistor. A second electrode of the fourth transistor is configured to input a first reference voltage.