Dot Inversion Multiplexer Architecture for LCD Line Mura Reduction
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Solution Overview
Problem
Conventional liquid crystal display devices using dot inversion mode with 1 to 6 multiplexers suffer from line mura effects due to identical polarity between certain pixel units, leading to crosstalk and incorrect gray level displays.
Innovation Solution
The proposed solution involves a liquid crystal display device with a gate driver and source driver generating alternating scan signal voltages and data voltages, where each pixel group receives alternating polarity data voltages through multiplexers, ensuring that each pixel unit shows gray levels based on the appropriate polarity voltage at specific intervals, thereby preventing voltage drifting and aligning liquid crystal molecules correctly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If dot inversion mode with 1 to 6 multiplexers is used, then the number of output pins of source drivers is reduced and cost is lowered, but line mura effects occur due to identical polarity between certain pixel units
Solution Approach 1:
The patent applies local quality by differentiating the polarity control for different pixel units within the same pixel group. Specifically, odd-numbered pixel units (1st, 3rd, 5th) and even-numbered pixel units (2nd, 4th, 6th) are assigned different polarities through separate data voltages (first polarity data voltage and second polarity data voltage). This local differentiation ensures that adjacent pixel units have opposite polarities, preventing the line mura effect while maintaining the cost benefits of using only 1 to 6 multiplexers.
2Ease of operation
If voltage across electrodes tends toward either polarity for a while, then device operation is simplified, but voltage-drifting phenomenon occurs causing incorrect gray levels
Solution Approach 1:
The patent implements periodic action through dot inversion mode, where the polarity of data voltages is periodically switched between positive and negative. Each pixel unit alternates between receiving positive polarity data voltage and negative polarity data voltage in successive frame periods. This periodic polarity switching prevents the voltage-drifting phenomenon by ensuring that the liquid crystal molecules are not subjected to unidirectional voltage stress for extended periods, thereby maintaining accurate gray level representation while keeping the voltage control mechanism relatively simple.
3Reliability
If voltages across electrodes are periodically switched between positive and negative polarity, then voltage-drifting is prevented, but complex multiplexer architecture is required
Solution Approach 1:
The patent applies segmentation by dividing pixel units into odd-numbered groups and even-numbered groups, where each group receives data voltages with different polarities. The odd-numbered pixel units receive first polarity data voltage while even-numbered pixel units receive second polarity data voltage with opposite polarity. This segmentation strategy enables effective polarity switching to prevent voltage-drifting while using a relatively simple multiplexer architecture (only 1 to 6 multiplexers), avoiding the need for more complex configurations.
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
This approach effectively reduces line mura between pixel units, improving display quality by ensuring accurate gray level representation and preventing voltage drifting, thus enhancing the overall performance of the liquid crystal display device.
Implementation Method 1
the alignment of the liquid crystal molecules fails to be varied based on the required control voltage
Implementation Method 2
opposed voltage difference value across the two electrodes results in the opposed alignments of the liquid crystal molecules
Implementation Method 3
the voltages across the two electrodes are periodically switched between positive polarity and negative polarity
Data Source
AI summary
A liquid crystal display device includes a gate driver for generating a first scan signal voltage and a second scan signal voltage, a source driver for generating a first polarity data voltage and a second polarity data voltage, and a liquid crystal display panel having a first pixel set and a second pixel set. Each first and second pixel set includes a first pixel and a second pixel. Both the first pixel of the first pixel set and the second pixel of the second pixel set display grey level based on the first polarity data voltage in response to the first scan signal voltage. Both the second pixel of the first pixel set and the first pixel of the second pixel set display grey level based on the second polarity data voltage in response to the second scan signal voltage.