Liquid Crystal Display Signal Correction for AC Afterimage Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Liquid crystal displays face challenges with afterimages due to residual DC voltages, particularly AC afterimages, which are difficult to address with existing asymmetrical gamma correction methods.
Innovation Solution
A liquid crystal display system that includes a signal controller with an image signal corrector, which shifts input image signal values for black, halftone, and white grays based on a common voltage, with specific dummy values applied to prevent AC afterimages by accumulating DC voltages differently for each gray level, and utilizes a copolymer alignment layer for improved alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If asymmetrical gamma correction method is applied to compensate for kickback voltage, then residual DC voltage and afterimage are reduced, but AC afterimage becomes a difficulty
Solution Approach 1:
The invention segments the gray levels into distinct categories (black gray, halftone gray, white gray) and applies different correction values to each segment. This allows targeted compensation for DC voltage residuals in black and halftone grays while maintaining natural appearance in white grays, thereby preventing AC afterimages that arise from uniform correction approaches.
Solution Approach 2:
The invention applies local quality by assigning different correction strategies to different gray levels: larger correction values for black and halftone grays where DC voltage accumulation is problematic, and no correction for white grays where AC afterimage prevention is critical. This localized approach optimizes afterimage prevention without introducing harmful AC effects.
2Reliability
If data voltage is compensatively applied for each grayscale to solve afterimage, then residual DC voltage is reduced, but separate correction for each gray increases device complexity
Solution Approach 1:
The invention divides the continuous gray scale into three discrete segments (black gray, halftone gray, white gray) and defines specific correction values for each segment. This segmentation approach simplifies the correction method compared to continuous per-gray correction while still effectively preventing afterimages.
Solution Approach 2:
The invention changes the correction parameter from a continuous per-gray adjustment to discrete fixed values for each gray segment. By using predetermined correction values (first correction value for black gray, second correction value for halftone gray, third correction value for white gray), the system reduces computational complexity while maintaining afterimage prevention effectiveness.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively prevents AC afterimages by optimizing voltage application across different gray levels, reducing the occurrence of afterimages at both room and high temperatures, thereby enhancing display visibility and image quality.
Implementation Method 1
The liquid crystal display includes a thin film transistor, and a gate line and a data line crossing each other are formed on a display panel of the liquid crystal display including the thin film transistor. An alignment state of the liquid crystal layer is determined according to an electric field formed between the pixel voltage Vp charged in the pixel and a common voltage Vcom applied in the common electrode.
Data Source
AI summary
A liquid crystal display includes: a signal controller configured to receive an input image signal corresponding to a gray from the outside, and an image signal corrector configured to correct the input image signal. The image signal corrector is configured to shift a first input image signal value corresponding to a black gray by a first value based on a common voltage, is configured to shift a second input image signal value corresponding to a halftone gray by a second value based on the common voltage, and is configured to shift a third input image signal value corresponding to a white gray by a third value based on the common voltage. The first value and the second value are larger than a kickback voltage of each of the black gray and the halftone gray, and the third value is the same as a kickback voltage of the white gray.