OLED Drive Transistor Dynamic Region Switching
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Solution Overview
Problem
Conventional organic light-emitting display devices consume high power due to driving the drive transistor in the saturation region of the current versus voltage curve, leading to increased power consumption and potential transistor deterioration.
Innovation Solution
The drive transistor is driven in a combination of the saturation and linear regions, with a lower high-level voltage being used compared to conventional methods, and an adaptive gamma curve is employed to adjust the data voltage based on grey-scale requirements, allowing for selective switching between driving schemes based on anticipated image quality deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the drive transistor is driven in the saturation region, then the display device can operate with stable current characteristics, but power consumption increases and transistor deterioration accelerates
Solution Approach 1:
The patent dynamically switches between saturation region driving and linear region driving based on gray level requirements. For low gray levels where high current stability is needed, saturation region driving is used. For high gray levels where power consumption is critical, linear region driving is used. This dynamic adaptation resolves the contradiction by optimizing the operating point according to real-time display requirements.
Solution Approach 2:
The patent changes the operating parameters of the drive transistor by adjusting the high-level voltage supplied to the drain. By varying the voltage level and the region of operation (saturation vs. linear), the patent achieves both low power consumption and adequate current stability across different gray levels, thereby resolving the technical contradiction.
2Reliability
If the drive transistor is driven in the saturation region, then current stability is maintained, but transistor deterioration occurs faster
Solution Approach 1:
The patent implements dynamic driving mode switching that adapts to gray level requirements. By using linear region driving for high gray levels and saturation region driving for low gray levels, the patent reduces cumulative stress on the transistor while maintaining necessary current stability, thereby extending transistor lifetime without sacrificing display quality.
Solution Approach 2:
The patent changes the operating parameters by selectively adjusting the high-level voltage and operating region based on gray level. This parameter optimization reduces transistor stress during high gray level display while maintaining current stability during low gray level display, effectively extending transistor operational life.
3Device complexity
If a single high-level voltage is used for driving, then circuit design is simplified, but power consumption cannot be optimized across different gray levels
Solution Approach 1:
The patent introduces dynamic voltage selection that switches between different high-level voltage values based on gray level requirements. Although this adds some circuit complexity for voltage selection and switching, it enables significant power consumption optimization by using lower voltages for high gray levels where full voltage is unnecessary, while maintaining adequate voltage for low gray levels where current stability is critical.
Data Source
AI summary
An organic light-emitting display device including a display panel, a power supply, a selective driver and a gamma change driver is disclosed. The display panel includes sub-pixels. The power supply is configured to output a drive voltage for driving the sub-pixels. The selective driver is configured to generate a control signal to enable selective drive between first and second driving schemes for a drive transistor in each sub-pixel, wherein the first and second schemes employ saturation and linear regions of the drive voltage curve respectively. The gamma change driver is configured to change a gamma based on the driving scheme selected by the selective driver.