OLED Pixel Circuit Voltage Regulation for Leakage Current
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Solution Overview
Problem
Organic light emitting diode (OLED) display panels experience picture flickering due to off-state leakage current in transistors, leading to deviations in driving current and brightness.
Innovation Solution
A pixel circuit with a driving transistor, control modules, and a voltage regulation module is introduced. The control modules include units connected in series with an intermediate node, and the voltage regulation module adjusts the voltage of these intermediate nodes during non-light-emission periods to maintain a preset voltage difference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If transistors are used in pixel circuits to drive light-emitting elements, then the display panel can achieve normal light emission and image display, but off-state leakage current causes electric leakage leading to driving current deviation and brightness flickering
Solution Approach 1:
A voltage regulation module is introduced as an intermediary component between the control module and the driving transistor. This module includes a regulation transistor whose gate is connected to a control signal line, and whose source/drain electrodes are connected to the gate of the driving transistor. The voltage regulation module dynamically adjusts the gate voltage of the driving transistor to compensate for leakage current effects, thereby maintaining stable driving current without affecting the normal switching function of the original transistor circuit.
Solution Approach 2:
The invention changes the voltage parameter at the gate of the driving transistor by introducing a voltage regulation module. During holding frames, the regulation transistor adjusts the gate voltage to compensate for the voltage drop caused by leakage current. This parameter adjustment ensures that the driving current remains within the standard range, preventing brightness deviation and flickering while maintaining the original circuit structure.
2Reliability
If voltage regulation module is added to reduce electric leakage, then driving current stability is improved, but device complexity increases
Solution Approach 1:
The voltage regulation module uses the same control signal line that already exists in the OLED display panel for driving control. The regulation transistor shares the control signal line with other pixel circuit components, allowing the voltage regulation function to be integrated into the existing control architecture without requiring additional independent control lines. This multi-functionality approach reduces the increase in device complexity while achieving driving current stabilization.
Data Source
AI summary
Present disclosure provide a pixel circuit and a driving method, a display panel, and a display apparatus. The pixel circuit includes: a driving transistor, a gate connected to a first node, a first electrode connected to a second node, a second electrode connected to a third node; a control module, connected to the first node and including a first unit and a second unit that are connected in series, an intermediate node arranged between first unit and second unit; a voltage regulation module, wherein a driving cycle of the pixel circuit includes a writing frame and holding frame, the writing frame includes a first non-light-emission period, the holding frame includes a second non-light-emission period, and the voltage regulation module is configured to adjust, in the second non-light-emission periods in holding frame, a voltage of intermediate node electrically connected thereto to a first voltage.