LCD Data Driver Polarity Inversion and Overdrive
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Solution Overview
Problem
Liquid crystal display (LCD) devices suffer from picture quality deterioration due to fixed DC voltage application, leading to residual images and current leakage from pixel regions, which is not effectively addressed by existing column inversion modes.
Innovation Solution
The proposed solution involves an LCD device with a data driver that applies data voltages with inverted polarity and over-drives gate lines during polarity inversions, using a gamma generator to produce gamma voltages that enhance the response speed of pixel regions, thereby minimizing current leakage and improving picture quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If column inversion mode is used to invert data voltage polarity, then DC voltage fixedness is prevented, but current leakage occurs from pixel regions due to polarity variation
Solution Approach 1:
The patent applies column inversion mode to invert the polarity of data voltages applied to adjacent data lines. Odd-numbered data lines are driven with positive polarity while even-numbered data lines are driven with negative polarity, and this inversion is exchanged between frames. This prevents DC voltage fixedness that would otherwise cause residual images and picture quality deterioration.
Solution Approach 2:
The patent changes the polarity parameter of data voltages applied to data lines. By varying the polarity between positive and negative depending on whether the data line is odd or even numbered, and exchanging this pattern between frames, the invention prevents DC voltage accumulation while managing current leakage effects through parameter variation.
2Reliability
If data voltage polarity is inverted for each frame, then picture quality deterioration is prevented, but pixel regions cannot be substantially charged due to voltage variation
Solution Approach 1:
The patent inverts the polarity of data voltages applied to data lines in a column inversion mode. Odd-numbered data lines receive positive polarity voltage while even-numbered data lines receive negative polarity voltage, and this pattern is exchanged between frames. This inversion prevents picture quality deterioration caused by DC voltage fixedness.
3Reliability
If polarity variation is applied to data voltage, then DC voltage fixedness is prevented, but current leaks out from pixel regions
Solution Approach 1:
The patent employs column inversion mode where the polarity of data voltages is inverted between adjacent data lines and exchanged between frames. Odd-numbered data lines are driven with positive polarity while even-numbered data lines are driven with negative polarity, preventing DC voltage fixedness that would cause residual images.
Solution Approach 2:
The patent varies the polarity parameter of data voltages applied to data lines. By changing the polarity between positive and negative based on whether the data line is odd or even numbered, and exchanging this pattern between frames, the invention prevents DC voltage accumulation while managing current leakage through parameter variation.
Data Source
AI summary
An LCD device is discussed which includes: a plurality of gate lines and a plurality of data lines arranged on a substrate; a data driver configured to apply data voltages the data lines; a gamma generator configured to apply a plurality of gamma voltages to the data driver, wherein the data line receives the data voltage which has an inverted polarity to those of data voltages on the adjacent data lines thereto, is inverted n times in polarity for every frame, and is over-driven for the gate lines opposite to time points of the polarity inversions.