Liquid Crystal Display Polarity Controller Preventing Data Voltage Lean
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Solution Overview
Problem
Active matrix liquid crystal displays suffer from a greenish phenomenon and reduced display quality due to polarities of data voltages leaning towards one polarity, causing crosstalk and luminance differences between neighboring lines.
Innovation Solution
A liquid crystal display system with a horizontal polarity controller that compares digital video data with critical values, inverts the logic state of a horizontal polarity conversion signal when polarities lean, and controls data voltage polarity inversion periods to prevent leaning, using a data drive circuit and gate drive circuit to manage scan signals and data voltages.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If horizontal and vertical 1 dot inversion scheme is used for data voltage polarity, then DC drive of liquid crystal is suppressed, but polarities lean to one polarity causing greenish phenomenon and luminance differences
Solution Approach 1:
The patent applies dynamics by making the polarity inversion scheme adaptive rather than fixed. The system dynamically switches between 1 dot inversion and 2 dot inversion schemes based on real-time analysis of data voltage polarity distribution. When polarity leaning is detected, the system changes the inversion pattern to correct the imbalance, making the DC suppression mechanism flexible and adaptive to different display conditions.
Solution Approach 2:
The patent changes the parameter of polarity inversion period from a fixed 1 dot pattern to a variable pattern that can switch between 1 dot and 2 dot inversion. By analyzing the polarity distribution of data voltages and detecting when leaning occurs, the system adjusts the inversion parameter to maintain balanced polarities, thereby preventing the greenish phenomenon while preserving DC suppression.
2Ease of operation
If common voltage is applied to common electrode, then liquid crystal display operates, but coupling between pixel electrode and common electrode causes common voltage to shift depending on screen location
Solution Approach 1:
The patent implements feedback by monitoring the polarity distribution of data voltages applied to the pixel electrode and using this information to adjust the polarity inversion scheme. The system detects when polarity leaning occurs and feeds this information back to the polarity controller, which then switches between different inversion patterns to correct the imbalance and stabilize the common voltage across the screen.
Data Source
AI summary
A liquid crystal display and a method of driving the same are disclosed. The liquid crystal display includes a liquid crystal display panel including data lines and gate lines crossing each other, and liquid crystal cells arranged in a matrix forma, a horizontal polarity controller that compares digital video data with a critical value and inverts a logic state of a horizontal polarity conversion signal when polarities of the digital video data lean based on the comparative result, a data drive circuit that converts the digital video data into positive and negative data voltages and controls horizontal polarity inversion periods of the data voltages in response to the horizontal polarity conversion signal, and a gate drive circuit that supplies scan signals to the gate lines.