AMOLED Pixel Driving Circuit Threshold Compensation
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Solution Overview
Problem
The poor uniformity of threshold voltages in driving transistors of AMOLED panels leads to variations in driving currents, resulting in non-uniform brightness in active matrix organic light-emitting diode (AMOLED) displays due to shifts during use.
Innovation Solution
A pixel driving circuit with a threshold compensation unit that provides a control voltage equal to the sum of the threshold voltage and data voltage to the driving transistor, independent of the threshold voltage, ensuring consistent driving current for improved brightness uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional 2T1C pixel driving circuit is used, then the circuit structure is simple, but the threshold voltage non-uniformity of driving transistors causes poor brightness uniformity
Solution Approach 1:
The pixel driving circuit is segmented into multiple functional modules: a threshold compensation unit with storage capacitors to store threshold voltage information, a data writing unit to write data voltage, and a driving unit with the driving transistor. This segmentation allows independent optimization of each module to achieve both simplicity and brightness uniformity.
Solution Approach 2:
The threshold compensation unit performs preliminary action by pre-storing the threshold voltage of the driving transistor in storage capacitors before the driving operation. This preliminary storage of threshold voltage information enables the circuit to compensate for threshold variations during the driving phase, ensuring brightness uniformity without increasing overall complexity.
2Illumination intensity
If threshold voltage compensation is implemented, then brightness uniformity is improved, but the circuit complexity increases
Solution Approach 1:
The storage capacitors in the threshold compensation unit serve multiple functions: they store threshold voltage information, maintain compensation voltages during different operation phases, and work cooperatively with the driving transistor to achieve both threshold compensation and data writing. This multi-functionality reduces the need for separate dedicated components, thereby limiting the increase in circuit complexity.
Solution Approach 2:
The threshold compensation function is merged with the data writing and driving functions in an integrated pixel driving circuit. The storage capacitors, driving transistor, and control switches work as a unified system where threshold compensation and data writing share common components and operation phases, reducing overall circuit complexity compared to separate compensation and driving circuits.
Data Source
AI summary
The present invention provides a pixel driving circuit, a pixel driving method, and a display device. The pixel driving circuit comprises a driving transistor, a light-emitting device and a threshold compensation unit; a control electrode, a first electrode and a second electrode of the driving transistor are all connected with the threshold compensation unit; the threshold compensation unit is connected with a data line, a first power supply terminal, and a first terminal of the light-emitting device. In the technical solution of the present invention, by providing the sum of the data voltage and the threshold voltage of the driving transistor to the control electrode of the driving transistor, a driving current generated by the driving transistor is independent of the threshold voltage of the driving transistor, so as to prevent the driving current from being influenced by non-uniformity and shift of the threshold voltage.