Liquid Crystal Display Common Voltage Correction
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Solution Overview
Problem
Conventional liquid crystal display devices experience picture quality degradation due to a greenish phenomenon caused by variations in common voltage, leading to uneven brightness across red, green, and blue pixel cells, resulting from opposite polarity image data being supplied to adjacent pixel rows.
Innovation Solution
A liquid crystal display device with a common voltage correction unit that calculates predominant-polarity data from adjacent pixel rows and adjusts the common voltage based on predetermined correction values to maintain balanced image data application across all pixel cells, preventing common voltage deviations that cause picture quality degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If opposite polarity image data is supplied to adjacent pixel rows, then switching element operation is enabled, but common voltage varies causing picture quality degradation
Solution Approach 1:
The patent changes the parameter of image data supplied to even pixel rows from opposite polarity to same polarity as odd pixel rows. This parameter change prevents common voltage variation while maintaining switching element operation, thereby resolving the contradiction between reliability and picture quality.
2Ease of operation
If first halftone image data is supplied to odd unit pixels and second halftone to even unit pixels, then striped pattern appears, but greenish phenomenon occurs degrading picture quality
Solution Approach 1:
The patent applies different image data strategies to different regions: odd pixel rows receive one type of image data while even pixel rows receive the same type, rather than using opposite polarities. This local differentiation approach enables halftone display while preventing the greenish phenomenon that degrades picture quality.
3Device complexity
If common voltage is not corrected, then device complexity is low, but brightness uniformity across pixel cells deteriorates
Solution Approach 1:
The patent implements a feedback mechanism where the polarity of image data supplied to even pixel rows is controlled to be the same as odd pixel rows, based on detection of the greenish phenomenon cause. This feedback control adjusts the voltage application strategy to maintain brightness uniformity while managing device complexity.
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 corrects common voltage variations, preventing the greenish phenomenon and maintaining balanced brightness across all pixel cells, thereby enhancing picture quality by ensuring accurate and consistent image data application.
Implementation Method 1
a liquid crystal layer disposed between the pixel electrode and the common electrode for adjusting light transmittance depending on an electric field generated between the two electrodes
Data Source
AI summary
The liquid crystal display device includes a liquid crystal panel including a common voltage correction unit that obtains predominant-polarity data based on polarities of image data to be supplied to pixel cells arranged in an nth one of pixel rows, obtains predominant-polarity data based on polarities of image data to be supplied to pixel cells arranged in an (n+1)th one of the pixel rows adjacent to the nth pixel row, obtains a sum of the two predominant-polarity data, and selects and outputting any one of a plurality of predetermined correction values based on the sum, and a common voltage output unit that corrects a common voltage based on the correction value from the common voltage correction unit and supplies the corrected common voltage to a common electrode.