Display Pixel Aperture Ratio for Luminance and Transistor Stress
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Solution Overview
Problem
The variation in stress applied to pixels due to material differences causes a shift in the threshold voltage of driving transistors, leading to inadequate luminance expression and potential flickering in display devices.
Innovation Solution
A method to determine the aperture ratio by calculating current density ratio, total stress, and threshold voltage variance, allowing for improved luminance expression and reduced stress on transistors, thereby enhancing display quality and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the aperture ratio is increased to improve luminance expression capability, then the luminance output is improved, but the current density increases which accelerates transistor aging and reduces pixel lifetime
Solution Approach 1:
The patent changes the aperture ratio parameter based on calculated stress values and current density ratios. By dynamically adjusting the aperture ratio to an optimized value that accounts for transistor stress characteristics, the system achieves improved luminance expression while preventing excessive current density that would accelerate transistor aging. This parameter optimization resolves the contradiction between luminance output and pixel lifetime.
2Adaptability or versatility
If materials with higher stress are used in pixels, then the manufacturing flexibility is improved, but the threshold voltage shifts beyond compensation range causing luminance degradation
Solution Approach 1:
The patent performs preliminary calculation of stress values and current density ratios before finalizing the aperture ratio determination. By pre-calculating these parameters based on material characteristics, the system can select materials with higher stress properties while still determining an aperture ratio that keeps the threshold voltage within the compensation range. This preliminary action prevents luminance degradation while maintaining material selection flexibility.
3Reliability
If the aperture ratio is optimized to extend pixel lifetime, then the reliability is improved, but the luminance expression capability is reduced
Solution Approach 1:
The patent optimizes the aperture ratio parameter by calculating the current density ratio and stress values to find an optimal balance point. Rather than simply reducing the aperture ratio to extend lifetime, the system determines an optimized aperture ratio that maintains adequate luminance expression capability while preventing excessive current density. This optimized parameter setting resolves the contradiction by achieving both reliability improvement and acceptable luminance performance.
Data Source
AI summary
A method of determining an aperture ratio includes: calculating a current density ratio of a pixel of a display device; calculating a total stress of the pixel based on lifetime data of the pixel and the current density ratio of the pixel; calculating a threshold voltage variance of a driving transistor included in the pixel; and determining the aperture ratio of the pixel based on a relationship between the total stress of the pixel and the threshold voltage variance of the driving transistor.