Liquid Crystal Display Overdrive Circuit Flicker Reduction
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Solution Overview
Problem
Conventional overdrive technologies in liquid crystal displays produce flicker in motion videos due to alternating differences in grey levels that are either greater than or less than a threshold, which existing methods fail to effectively mitigate.
Innovation Solution
An overdrive method that calculates a gain based on the difference between current and previous grey levels, using a continuous increasing function, and mixes the overdrive grey level with the current grey level to generate a smooth output grey level, preventing flicker by adjusting the grey level progressively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional overdrive technology is used to shorten response time by adjusting grey levels, then response time is improved, but flicker occurs in motion videos due to alternating grey level differences above and below the threshold
Solution Approach 1:
The patent applies dynamics by making the overdrive adjustment dynamic rather than static. Instead of using a fixed threshold for grey level adjustment, the system dynamically determines whether to apply overdrive based on whether the grey level difference is above or below the threshold. When below the threshold, progressive adjustment is used to maintain stability and prevent flicker, while still allowing response time improvement when differences are larger.
Solution Approach 2:
The patent changes the parameter of grey level adjustment from a binary on/off approach to a progressive continuous adjustment. By introducing progressive adjustment that modifies the overdrive amount based on the magnitude of grey level difference, the system maintains response time benefits while eliminating the flicker caused by abrupt threshold-based switching.
2Manufacturing precision
If overdrive adjustment is applied to all grey level changes to maintain image quality, then image quality is improved, but flicker is generated when grey level differences alternate around the threshold
Solution Approach 1:
The patent applies local quality by differentiating the treatment of different grey level differences. Instead of uniformly applying overdrive to all changes, the system applies different adjustment strategies: full overdrive when differences are significant, and progressive adjustment when differences are small. This localized approach maintains image quality where needed while preventing flicker in subtle transitions.
Solution Approach 2:
The system dynamically adapts the overdrive strategy based on the local characteristics of each grey level transition. By continuously monitoring the magnitude of grey level differences and adjusting the overdrive amount accordingly, the system maintains high image quality while dynamically preventing flicker in regions where grey levels alternate around the threshold.
Data Source
AI summary
An overdrive method includes: performing loss compression to an input image to generate image data, and storing the image data into a memory; reading the image data from the memory and decoding the image data to obtain a previous image; obtaining a current image, calculating a difference between a current grey level at a location of the current image and a previous grey level of the previous image at the location; calculating a gain according to the difference and a threshold; calculating an overdrive grey level according to the current grey level and the previous grey level; and mixing the overdrive grey level and the current grey level based on the gain to generate an output grey level to replace the current grey level.