Pixel Driving Circuit for AMOLED Brightness Uniformity
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Solution Overview
Problem
Active Matrix Organic Light Emitting Diode (AMOLED) panels face issues with poor brightness uniformity due to non-uniform threshold voltages of driving transistors and reduced brightness over time as the turn-on voltage increases with aging, leading to decreased display quality.
Innovation Solution
A pixel driving circuit that includes a turn-on voltage acquiring device, a compensation device, a light-emitting controller, a data writing device, and a driving transistor, which generates a compensation signal based on the turn-on voltage and threshold voltage to ensure the driving current is independent of the threshold voltage and correlated with the turn-on voltage, improving brightness uniformity and compensating for aging-related brightness reduction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional driving circuits are used without turn-on voltage compensation, then the circuit structure is simple, but brightness uniformity is poor due to non-uniform threshold voltages and aging effects
Solution Approach 1:
The patent measures and stores the turn-on voltage of the light emitting device in advance during a testing phase. This pre-acquired voltage information is then used during normal operation to compensate for threshold voltage variations and aging effects, eliminating the need for real-time complex measurements while maintaining high brightness uniformity
Solution Approach 2:
The patent introduces a turn-on voltage acquiring device that acts as an intermediary to measure and store the turn-on voltage characteristics of the light emitting device. This intermediary component enables the system to compensate for device variations without requiring complex real-time control circuits, thus improving brightness uniformity while keeping the overall structure manageable
2Reliability
If no compensation for turn-on voltage changes is implemented, then the device complexity is low, but brightness decreases over time due to aging
Solution Approach 1:
The patent performs preliminary measurement and storage of the turn-on voltage during an initial testing phase. This pre-acquired information serves as a reference for ongoing compensation, allowing the system to maintain stable brightness over time without requiring continuous complex measurements or adjustments
Solution Approach 2:
The patent implements a feedback mechanism where the stored turn-on voltage information is continuously referenced during operation. The driving current is adjusted based on this stored information to compensate for aging effects, creating a closed-loop system that maintains brightness stability without requiring complex real-time sensing circuits
Data Source
AI summary
A pixel driving circuit and a driving method therefor are provided. The pixel driving circuit includes a turn-on voltage acquiring device, a compensation device, a light-emitting controller, a data writing device, a driving transistor and a light emitting device. The turn-on voltage acquiring device acquires a turn-on voltage of the light emitting device and generates a compensation signal according to the turn-on voltage; the data writing device provides a data voltage to the gate of the driving transistor; the light-emitting controller provides a first operating voltage to a first electrode of the driving transistor; and the compensation device generates a control signal according to the compensation signal, the data voltage and the threshold voltage of the driving transistor and provides the control signal to the gate of the driving transistor; the driving transistor outputs a driving current to the light emitting device.