AMOLED Pixel Driving Circuit Reducing Current Leakage
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Solution Overview
Problem
Existing pixel driving circuits in AMOLED display devices experience current leakage and flicker issues due to long light-emitting times, especially when driven at low frequencies, leading to display instability and non-uniform brightness.
Innovation Solution
A pixel driving circuit design that includes a driving transistor, power control sub-circuit, data writing-in sub-circuit, and reset control sub-circuits, along with capacitor units, which control the connection and disconnection of nodes to manage voltage states and reduce current leakage, ensuring stable operation even at low frequencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the light-emitting element operates for a long duration to achieve low-frequency driving, then the display can operate at lower refresh rates, but the gate electrode of the driving transistor experiences serious current leakage
Solution Approach 1:
The pixel driving circuit is divided into multiple functional sub-circuits: a driving sub-circuit for controlling the light-emitting element, a compensation sub-circuit for compensating threshold voltage changes, a reset sub-circuit for resetting the driving transistor, and a control sub-circuit for coordinating operations. This segmentation allows each sub-circuit to independently manage specific functions, reducing overall current leakage while maintaining low-frequency operation capability
Solution Approach 2:
The compensation sub-circuit performs preliminary compensation for threshold voltage changes before the light-emitting element operates. By pre-adjusting the gate electrode voltage to account for expected threshold shifts, the circuit reduces current leakage that would otherwise accumulate during long-duration operation at low refresh rates
2Productivity
If the light-emitting element operates for a long duration, then low-frequency driving is achieved, but the display becomes prone to flicker
Solution Approach 1:
The compensation sub-circuit implements a feedback mechanism that continuously monitors and compensates for threshold voltage changes in the driving transistor. This real-time feedback adjustment maintains stable driving current despite long operation durations, eliminating flicker while enabling low-frequency refresh rates
Solution Approach 2:
The control sub-circuit dynamically adjusts operating parameters including gate electrode voltage and timing sequences based on detected threshold voltage changes. By modifying these parameters in response to circuit state changes, the system maintains display stability during extended light-emitting periods at low refresh rates
3Productivity
If the light-emitting time is extended for low-frequency operation, then refresh rate is reduced, but the driving current becomes non-uniform
Solution Approach 1:
The pixel circuit is segmented into specialized sub-circuits, each optimized for specific functions. The driving sub-circuit maintains current uniformity through dedicated compensation mechanisms, while the reset sub-circuit ensures consistent initialization. This functional segmentation preserves driving current uniformity even during extended operation at low refresh rates
Solution Approach 2:
The reset sub-circuit performs preliminary resetting of the driving transistor before each light-emitting period, ensuring consistent initial conditions. The compensation sub-circuit also performs preliminary adjustment for expected threshold voltage drift, both actions working together to maintain driving current uniformity throughout extended operation
Data Source
AI summary
The present disclosure provides a pixel driving circuit, a method of driving the same, and a display device. In the pixel driving circuit, under the control of a gate line, a data writing-in sub-circuit controls to connect or disconnect a data line and a first common node, and controls to connect or disconnect the first common node and a gate electrode of the driving transistor; under the control of a reset signal line, a first reset control sub-circuit controls to connect or disconnect a reference voltage input terminal and a second common node, and controls to connect or disconnect the second common node and the gate electrode of the driving transistor; a first end of a third capacitor unit is connected to the first common node and/or the second common node, and a second end of the third capacitor unit is connected to the first electrode of the driving transistor.