3T1C OLED Pixel Driving Circuit for Threshold Compensation
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Solution Overview
Problem
Conventional OLED pixel driving circuits face challenges in maintaining uniformity of image display quality due to variations in voltage threshold and intrinsic conductivity factor of driving TFTs, which degrade over time, leading to non-uniform illuminance and reduced efficiency.
Innovation Solution
A 3T1C OLED pixel driving circuit with a displaying mode and a detecting mode, where transistors and ADCs are used to detect and compensate for voltage threshold and conductivity factor drifts, ensuring uniform data compensation and improved illuminating efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional 2T1C pixel driving circuit is used to convert voltage signals into current signals, then the circuit structure is simple, but the uniformity of image display quality deteriorates due to variations in voltage threshold and intrinsic conductivity factor of driving TFTs
Solution Approach 1:
The patent applies parameter changes by detecting the actual voltage threshold and intrinsic conductivity factor of each driving TFT through the 3T1C circuit, then compensating the data voltage based on these detected parameters. This allows the system to adapt to variations in TFT characteristics and maintain uniform display quality across different pixels.
Solution Approach 2:
The patent implements feedback by using the detected voltage threshold and conductivity factor values to adjust the data voltage applied to each driving TFT. The feedback loop ensures that variations in TFT parameters are compensated, thereby maintaining consistent image display quality across the panel.
2Duration of action of moving object
If the driving TFT operates continuously over time, then the display function is maintained, but the voltage threshold and intrinsic conductivity factor drift, leading to non-uniform illuminance
Solution Approach 1:
The patent applies preliminary action by detecting the voltage threshold and conductivity factor of each driving TFT before the actual display operation. These detected values are stored and used to compensate for any future drift, ensuring uniform illuminance is maintained throughout the display operation.
Solution Approach 2:
The patent uses feedback by continuously monitoring and detecting the electrical characteristics of the driving TFT and adjusting the data voltage accordingly. This feedback mechanism compensates for parameter drift over time, maintaining uniform display quality throughout the operational duration.
3Manufacturing precision
If data compensation is implemented to correct voltage threshold and conductivity factor variations, then the uniformity of illuminance is improved, but the device complexity increases due to additional transistors and ADCs
Solution Approach 1:
The patent applies parameter changes by using the additional transistors and ADCs to detect and measure the electrical parameters (voltage threshold and conductivity factor) of the driving TFT. These measured parameters are then used to adjust and compensate for variations, achieving uniform illuminance despite the increased circuit complexity.
Data Source
AI summary
The present disclosure provides an OLED pixel driving circuit and an OLED display apparatus utilizing the circuit scheme of 3T1C. The normal displaying mode and detecting mode of the pixel driving circuit both include two phases by controlling the conductions of different transistors. And, the pixel driving circuit is capable of implementing corresponding data compensation under the displaying mode according to the detected voltage threshold Vth of the driving TFT and the intrinsic conductivity factor value k of the aged OLED. This is capable of improving the uniformity of display and the illuminating efficiency.