LCD Polarity Control for Vertical Noise Reduction
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Solution Overview
Problem
Liquid crystal display (LCD) devices generate noise due to vibrations of circuit elements caused by large voltage differences during the display of specific patterns, such as vertical alternating white-black patterns, which results in noise generation.
Innovation Solution
An LCD device with an image analyzer and a polarity control signal modulator that analyzes image data and modulates the polarity control signal to prevent polarity inversion of gray-scale data with large voltage differences, applying the same polarity data voltages to adjacent pixels in the vertical direction to reduce vibrations and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a horizontal 2-dot and vertical 2-dot inversion system is used to drive the LCD device, then liquid crystal deterioration is reduced, but noise is generated due to large voltage differences causing circuit element vibrations
Solution Approach 1:
The patent applies different polarity control strategies to different gray-scale levels. Specifically, black gray-scale data voltages with large voltage differences are excluded from polarity inversion, while white gray-scale data voltages with small voltage differences continue to undergo polarity inversion. This localized differentiation resolves the contradiction by maintaining the benefits of polarity inversion for low-risk cases while preventing noise for high-risk cases.
Solution Approach 2:
The patent changes the polarity control parameter based on the voltage difference magnitude. By analyzing the absolute difference between positive and negative data voltages for each gray-scale level, the system dynamically adjusts whether polarity inversion is applied. This parameter-based control allows the system to optimize between liquid crystal protection and noise reduction for each specific gray-scale level.
2Reliability
If polarity inversion is applied to black gray-scale data voltages with large voltage differences, then liquid crystal deterioration is reduced, but circuit elements vibrate causing noise generation
Solution Approach 1:
The patent implements preliminary analysis of the image data to identify black gray-scale patterns with large voltage differences before applying polarity control. By detecting these specific patterns in advance, the system can prevent polarity inversion for cases that would cause circuit element vibration, while still applying polarity inversion to other cases that benefit from liquid crystal protection without causing vibration.
3Object-generated harmful factors
If the same polarity data voltages are applied to adjacent pixels in the vertical direction, then noise is reduced, but the polarity inversion benefit for liquid crystal protection is lost
Solution Approach 1:
The patent applies polarity control strategies locally based on the specific gray-scale level and voltage difference characteristics. Rather than uniformly applying or excluding polarity inversion across all pixels, the system selectively applies polarity inversion only to white gray-scale data voltages with small voltage differences, while excluding black gray-scale data voltages with large voltage differences. This localized approach maintains noise reduction benefits while preserving liquid crystal protection where applicable.
Data Source
AI summary
An LCD device includes: a liquid crystal panel configured to include liquid crystal cells formed in regions defined by crossing gate lines and data lines; an image analyzer configured to analyze whether or not an image data corresponds to a specific pattern in which a black or white gray-scale data having a large difference between positive and negative data voltages is continuously opposed to the liquid crystal cells of a vertical direction; a polarity control signal modulator configured to respond to a control signal from the image analyzer and modulate a polarity control signal, so as to prevent the black gray-scale data continuously opposed to the liquid crystal cells of the vertical direction from being polarity-inverted; and a data driver configured to apply the data voltages to the data lines on the basis of the modulated polarity control signal applied from the polarity control signal modulator.