LCD Driving Circuit Dynamic Gradation Compensation
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Solution Overview
Problem
Typical LCD devices suffer from residual image phenomenon and flicker due to slow liquid crystal molecule response speed, and existing solutions like black image insertion reduce brightness and cause viewer perception of flicker.
Innovation Solution
An LCD system with a driving circuit comprising a frame memory, comparator, luminance detector, calculator, and gradation processor that generates pairs of compensating gradations based on comparison results, luminance, and picture complication degree to maintain image brightness and reduce flicker.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If black image insertion method is used to eliminate residual image, then residual image is reduced, but brightness is reduced and flicker is perceived
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the gradation values of compensation images based on the complexity of the displayed image content. Instead of using fixed black images, the system varies the luminance parameters of compensation images to match the scene complexity, thereby eliminating residual images while maintaining overall brightness and avoiding flicker perception.
2Reliability
If black image is displayed in each second sub-frame to reduce residual image, then residual image is eliminated, but flicker phenomenon occurs
Solution Approach 1:
The system dynamically changes the luminance parameters of compensation images based on scene complexity. By adjusting the brightness parameter of compensation images to match the displayed content complexity, the patent eliminates residual images while maintaining temporal luminance consistency, thereby preventing flicker perception.
3Device complexity
If slow liquid crystal molecule response speed is accepted, then device complexity is reduced, but residual image phenomenon occurs
Solution Approach 1:
The patent applies preliminary action by displaying compensation images before the actual image content. These pre-displayed compensation images prepare the liquid crystal molecules for the upcoming content by setting appropriate molecular orientations, thereby reducing residual image effects without requiring faster liquid crystal response or adding complex hardware.
Data Source
AI summary
An exemplary LCD includes a frame memory configured for receiving a plurality of first gradations of current frame and outputting a plurality of second gradations of preceding frame pre-stored therein; a comparator configured for receiving, comparing the first gradations with the second gradation to generate a comparison result; a luminance detector configured for detecting a luminance degree of each of pixel according to the gradations of current frame; a calculator configured for calculating a complication degree of a picture to be displayed in current frame; and a gradation processor configured for receiving the first gradations of current frame to be displayed on the LCD panel, generating a plurality of pairs of compensating gradations according to the gradation of each pixel, and selecting one pair of the compensating gradations to be outputted to the LCD panel according to a received comparison result, a received luminance degree, and a received complication degree.