OLED Pixel Circuit Threshold Voltage Read Time Extension
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Solution Overview
Problem
High-resolution OLED panels face challenges in reading the threshold voltage of driving thin film transistors (DTFTs) due to shortened allocated read time, leading to uneven display and mura (visual defects) due to the irregularity of low temperature polysilicon crystal particles.
Innovation Solution
A pixel circuit comprising a node control circuit, driver, display sub-circuit, threshold compensator, and reset device, which includes transistors and capacitors to adjust and read the threshold voltage, extending the read time through additional scanning signals and periods, allowing for accurate voltage adjustments and compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If high-resolution OLED panel is used, then display quality is improved, but allocated read time for threshold voltage reading is shortened
Solution Approach 1:
The pixel circuit is divided into multiple functional modules including node control circuit, driver, display sub-circuit, threshold compensator, and reset device. Each module performs specific functions during different time periods, allowing the threshold voltage reading to be segmented into dedicated time slots that extend the total read time while maintaining high display resolution
Solution Approach 2:
The circuit performs preliminary actions by establishing multiple scanning signal lines (first scanning signal line, second scanning signal line, third scanning signal line) and configuring transistors to be activated in specific sequences. This preliminary configuration enables extended threshold voltage reading time to be achieved before the actual display operation, ensuring accurate compensation for LTPS crystal irregularity
2Stability of the object's composition
If pixel compensation is performed for each pixel, then luminance uniformity is improved, but circuit complexity increases
Solution Approach 1:
The pixel circuit uses universal components such as multiple switching transistors (first switching transistor, second switching transistor, third switching transistor, fourth switching transistor, fifth switching transistor, sixth switching transistor) and capacitors that serve multiple functions across different time periods. These components are involved in threshold voltage reading, data writing, compensation, and display control, reducing the need for additional dedicated components and thereby limiting circuit complexity increase
Solution Approach 2:
The circuit merges the threshold voltage reading function, data writing function, and compensation function into a single integrated pixel circuit structure. The node control circuit, driver, display sub-circuit, threshold compensator, and reset device work together in a unified system, allowing pixel compensation to be performed without requiring separate independent circuits for each function
Data Source
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AI summary
A pixel circuit and a driving method therefor, and a display panel. The circuit comprises: a node control circuit (11), a driver (12), a display sub-circuit (13), a threshold compensator (14), and a resetting device (15). The node control circuit (11) is configured to output a voltage (Vref) of a reference voltage terminal to a first node (N1), or output a voltage (Vdata) of a data voltage terminal to the first node (N1); the driver (12) is configured to output a drive current; the display sub-circuit (13) is configured to display a gray scale; the threshold compensator (14) is configured to adjust a voltage of a second node (N2) to the sum of a voltage (V1) of a first level terminal and a threshold voltage of the driver (12), and adjust the voltage of the second node (N2) to a difference between the sum of the voltage (V1) of the first level terminal, the threshold voltage of the driver (12), and the voltage (Vref) of the reference voltage terminal and the voltage (Vdata) of the data voltage terminal; and the resetting device (15) is configured to reset the second node (N2) and the display sub-circuit (13).