OLED Pixel Driving Circuit Threshold Voltage Compensation
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Solution Overview
Problem
Conventional OLED pixel driving circuits face issues with non-uniformity due to inconsistent threshold voltages of driving TFTs, leading to display unevenness, and require additional reference voltages that reduce aperture ratio and increase manufacturing costs.
Innovation Solution
A 4T1C OLED pixel driving circuit with a switch, DAC, and ADC, operating in display and sense modes, compensates for threshold voltage impacts by sensing and adjusting the voltage of the driving TFT, eliminating the need for additional reference voltages and reducing the number of channels in the driving IC.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a 3T1C structured OLED pixel driving circuit is used to compensate for threshold voltage, then display uniformity is improved, but aperture ratio is reduced and manufacturing cost increases
Solution Approach 1:
The patent merges the reference voltage generation function into the existing pixel circuit structure. The fourth TFT and capacitor work together to generate the reference voltage locally within the pixel circuit, eliminating the need for separate reference voltage routing and additional channels in the driving IC, thus improving aperture ratio while maintaining compensation functionality
Solution Approach 2:
The pixel circuit performs self-compensation by using its own components (fourth TFT and capacitor) to generate the reference voltage needed for threshold voltage compensation. The circuit senses its own threshold voltage and adjusts the data signal accordingly, making the system self-sufficient without external reference voltage sources
2Manufacturing precision
If a 3T1C structured OLED pixel driving circuit is used to compensate for threshold voltage, then display uniformity is improved, but the number of channels in driving IC increases
Solution Approach 1:
The patent combines the reference voltage generation function with the existing pixel circuit components. The fourth TFT and capacitor are utilized within the pixel circuit itself to generate the reference voltage, eliminating the need for separate reference voltage channels in the driving IC and reducing overall device complexity
Solution Approach 2:
The pixel circuit generates its own reference voltage using internal components (fourth TFT and capacitor), making the system self-sufficient. This self-service approach eliminates the need for external reference voltage channels in the driving IC, reducing the number of channels and simplifying the overall system architecture
Data Source
AI summary
The invention provides an OLED pixel driving circuit and OLED display device. The OLED pixel driving circuit uses 4T1C structure and switch (K). The first pin (K1) of switch (K) is connected to the drain of the third TFT (T3), the second pin (K2) connected to the DAC (DAC), and the third pin (K3) connected to the ADC (ADC). By the switch signal (Switch) controlling the switch (K), the first pin (K1) and the second pin (K3) are connected to enter the display mode, and by the switch signal (Switch) controlling the switch (K), the first pin (K1) and the third pin (K3) are connected to enter the sense mode, so that the ADC (ADC) senses the threshold voltage of the fourth TFT (T4), converted by ADC (ADC) for data compensation in the display mode. The invention can compensate, improve display uniform, improve pixel aperture ratio and reduce manufacturing cost.