OLED Pixel Driving Circuit for Afterimage Reduction
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Solution Overview
Problem
Existing pixel driving circuits in OLED displays face issues with afterimages due to hysteresis effects and inadequate control over the initialization and data writing phases, leading to suboptimal light-emission performance.
Innovation Solution
A pixel driving circuit with a driving sub-circuit, light-emission control sub-circuits, data write sub-circuit, compensation sub-circuit, and reset sub-circuits, including adjustable pulse widths for reset signals, ensures a fixed voltage difference and independent control of initialization phases, improving afterimage reduction and time balance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing pixel driving circuits are used, then the circuit structure is simple, but afterimages occur due to hysteresis effects and inadequate control
Solution Approach 1:
The pixel driving circuit is divided into multiple sub-circuits: a driving sub-circuit for controlling the light-emitting element, a data write sub-circuit for writing data signals, a compensation sub-circuit for threshold voltage compensation, and a reset sub-circuit for initializing nodes. This segmentation allows each sub-circuit to perform its specific function optimally, reducing afterimages while maintaining manageable complexity through modular design.
Solution Approach 2:
The reset sub-circuit performs preliminary initialization of the control terminal and first terminal before data writing and light emission. By pre-setting the voltage states of these nodes, the circuit eliminates residual charges that cause hysteresis effects and afterimages, ensuring clean starting conditions for each display frame.
2Productivity
If initialization and data writing phases are not independently controlled, then the control mechanism is simple, but time balance between phases is suboptimal
Solution Approach 1:
The circuit employs dynamic control signals with adjustable pulse widths for different phases. The reset signal, data write signal, and light emission signal can be independently tuned in duration and timing, allowing optimization of the time allocation between initialization, data writing, and light emission phases to achieve better overall time balance and productivity.
3Reliability
If fixed voltage difference is not ensured in initialization phase, then the control is simple, but light-emission performance is suboptimal
Solution Approach 1:
The compensation sub-circuit provides feedback control by monitoring and compensating for threshold voltage variations in the driving transistor. This feedback mechanism ensures that the voltage difference between the control terminal and first terminal remains at the optimal fixed value during initialization, improving light-emission performance while the complexity is managed through dedicated compensation circuitry.
Data Source
AI summary
A pixel driving circuit (31) includes: a driving sub-circuit (311), a first light-emission control sub-circuit (312), a second light-emission control sub-circuit (313), a data write sub-circuit (314), a compensation sub-circuit (315) and a first reset sub-circuit (316). The driving sub-circuit (311) includes a control terminal, a first terminal and a second terminal; and in an initialization phase (t1) in one display frame of the pixel driving circuit (31), a voltage difference between the control terminal of the driving sub-circuit (311) and the first terminal of the driving sub-circuit (311) is fixed. A pulse width of the signal of the first reset signal control terminal is adjustable.