Display Grayscale Control for High-Frequency Mura Reduction
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Solution Overview
Problem
As resolution and driving frequency of display devices increase, the charging time for data voltage decreases, leading to a decrease in charging ratio, which results in mura and deteriorated display quality.
Innovation Solution
A display device with a driving controller that adjusts the first and second reference grayscales based on driving frequency, determining a low grayscale range and output ratio to enhance the charging ratio of pixels, thereby preventing mura by ensuring accurate grayscale display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the driving frequency is increased, then the productivity is improved, but the charging ratio decreases leading to mura and deteriorated display quality
Solution Approach 1:
The patent applies dynamics by making the grayscale output adaptive to the driving frequency. The driving controller dynamically adjusts the grayscale conversion process based on the detected driving frequency, switching between different grayscale determination methods (first grayscale determination for lower frequencies, second grayscale determination for higher frequencies) to optimize both display quality and charging ratio under varying operating conditions.
Solution Approach 2:
The patent implements parameter changes by modifying the grayscale conversion parameters based on driving frequency. When the driving frequency exceeds a threshold, the system changes the grayscale determination parameters to output only specific grayscale values (e.g., first and second reference grayscales) rather than the full range, thereby reducing the voltage swing and improving the charging ratio while maintaining acceptable display quality.
2Manufacturing precision
If the resolution is increased, then the manufacturing precision is improved, but the charging time decreases leading to lower charging ratio
Solution Approach 1:
The patent addresses this contradiction by changing the grayscale output parameters based on driving frequency. When high resolution driving modes operate at higher frequencies, the system adjusts the grayscale conversion to output fewer distinct grayscale levels, which reduces the voltage swing required and allows the pixel capacitors to charge more completely within the reduced charging time, thereby maintaining display quality despite shorter charging durations.
Solution Approach 2:
The patent applies partial action by selectively outputting only certain reference grayscale values (first and second reference grayscales) instead of the full grayscale range when operating at high driving frequencies. This partial grayscale output reduces the overall voltage swing required, enabling sufficient charging within the limited charging time while still providing adequate display quality for the given operating conditions.
3Productivity
If the charging time is decreased, then the productivity is improved, but the charging ratio decreases causing mura
Solution Approach 1:
The patent resolves this contradiction by dynamically changing the grayscale conversion parameters based on the driving frequency. When the driving frequency increases and charging time decreases, the system adjusts the grayscale output to use fewer distinct levels with smaller voltage differences, which allows the pixel capacitors to achieve sufficient charging ratio within the reduced time window, preventing mura while maintaining high productivity.
Data Source
AI summary
A display device includes: a display panel including a plurality of pixels; a driving controller configured to generate output image data based on input image data; and a data driver configured to generate a data voltage based on the output image data, wherein the driving controller is configured to: determine a low grayscale range in which a minimum grayscale is a first reference grayscale and a maximum grayscale is a second reference grayscale based on a driving frequency; and determine an output ratio and an output order of first reference output image data corresponding to the first reference grayscale and second reference output image data corresponding to the second reference grayscale.