Pixel Driving Circuit Voltage Maintaining Module
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Solution Overview
Problem
Current pixel driving circuits in organic light-emitting display devices cause uneven brightness due to changes in voltage across the light-emitting elements, affecting the driving current and resulting in inconsistent display quality.
Innovation Solution
A pixel driving circuit with a voltage maintaining module that keeps the voltage of the node between the driving transistor and the light-emitting element constant, using P-type and N-type transistors to regulate currents and maintain the voltage, thereby isolating the driving current from changes in the light-emitting element's voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional pixel driving circuit is used, then the circuit structure is simple, but the voltage across the light-emitting element changes causing uneven brightness
Solution Approach 1:
The patent introduces an intermediate node (third node) between the driving transistor and light-emitting element, and uses a voltage maintaining module to stabilize the voltage at this intermediate node. This mediator isolates the driving transistor from voltage changes at the light-emitting element, preventing brightness unevenness without requiring complete circuit redesign.
Solution Approach 2:
The voltage maintaining module implements a feedback mechanism by detecting voltage changes at the third node and adjusting the current through the first transistor accordingly. This feedback loop ensures the voltage at the third node remains stable despite changes in light-emitting element characteristics, maintaining uniform brightness.
2Reliability
If the voltage across the light-emitting element is allowed to change, then the circuit operation is simple, but the driving current is affected causing uneven display quality
Solution Approach 1:
The patent segments the circuit into distinct functional sections: the driving transistor section, the voltage maintaining module with the first transistor, and the light-emitting element section. This segmentation allows the voltage maintaining module to independently stabilize voltage without affecting the overall circuit operation, improving display consistency while keeping the added complexity localized.
Data Source
AI summary
A pixel driving circuit includes a driving transistor connected in series between a first power supply voltage terminal and a second power supply voltage terminal. The driving transistor has a control terminal electrically connected to a first node, a first terminal electrically connected to a second node, and a second terminal electrically connected to a third node. The second node is located between the first power supply voltage terminal and the driving transistor. The third node is located between the second power supply voltage terminal and the driving transistor. A light-emitting element is connected in series between the third node and the second power supply voltage terminal. A voltage maintaining module is configured to maintain a voltage of the third node unchanged.