Pixel Circuit Layout for Stable Driving Transistor Gate Voltage
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Solution Overview
Problem
Existing pixel circuits in display devices face issues with adverse effects on driving characteristics due to capacitors connected in series between the gate terminal of the driving transistor and the power voltage terminal, affecting the robustness and efficiency of light emission.
Innovation Solution
The pixel circuit is redesigned with a series connection of transistors and capacitors that include a first transistor controlled by a light-emission control signal, a driving transistor controlled by a gate signal, and additional transistors controlled by scan and initialization signals, allowing for improved voltage application and compensation, reducing adverse effects on the driving transistor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If capacitors are connected in series between the gate terminal of the driving transistor and the power voltage terminal, then voltage storage and compensation are improved, but driving characteristics and light emission robustness deteriorate
Solution Approach 1:
The harmful capacitors connected in series between the gate terminal and power voltage terminal are removed from the circuit. This extraction eliminates the adverse effects on driving characteristics while preserving the essential voltage storage and compensation functions through alternative circuit configurations.
Solution Approach 2:
The voltage storage and compensation functions are segmented into separate circuit elements: the first capacitor stores voltage at the first node, the second capacitor stores voltage at the second node, and the third capacitor provides compensation. This segmentation allows each capacitor to perform its function independently without the harmful series connection effects.
2Device complexity
If a simple transistor configuration is used, then device complexity is reduced, but voltage control precision and current stability deteriorate
Solution Approach 1:
Multiple transistors (first, second, third, fourth, and driving transistors) are merged into a coordinated circuit configuration where each transistor performs a specific function: switching, voltage application, compensation, and current control. This combination achieves precise voltage control and stable current while maintaining reasonable device complexity.
Solution Approach 2:
The third capacitor provides feedback compensation to the driving transistor, ensuring stable voltage levels and consistent current control. This feedback mechanism maintains manufacturing precision without requiring overly complex transistor configurations.
Data Source
AI summary
A pixel includes a first transistor connected between a first power voltage terminal and a first node and turned on and off by a first light-emission control signal, a driving transistor connected in series with the first transistor and a light-emitting element and turned on and off by a signal applied to a gate terminal of the driving transistor, a second transistor connected between a data line and a second node connected to the gate terminal of the driving transistor, and turned on and off by a scan signal, a first capacitor connected between the first power voltage terminal and the first node, and a second capacitor connected between the first node and the second node.