Data Driver Polarity Phase Adjustment for LCD Flicker
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Solution Overview
Problem
Large-screen liquid crystal display apparatuses face issues with image quality deterioration due to insufficient charging of pixels with gradation data signals having positive polarity, leading to flicker and non-uniform transmittance, especially with increased screen size and resolution, where the shorter data period and increased wiring resistance and capacitance result in reduced pixel charging rates.
Innovation Solution
The display apparatus employs column inversion drive with phased differences in gradation data signals having positive and negative polarities, adjusting output delay times and phases to optimize charging efficiency, ensuring balanced pixel charging rates across the screen, even with bluntness in gate selection signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the screen size and resolution are increased, then the display quality is improved, but the pixel charging rate decreases due to shorter data period and increased wiring resistance and capacitance
Solution Approach 1:
The patent applies dynamics by making the data period variable rather than fixed. Specifically, it extends the data period for pixels receiving positive polarity signals while shortening it for negative polarity signals, allowing the charging time to be dynamically adjusted based on polarity to ensure uniform charging rates across all pixels despite the constraints of high resolution and large screen size
Solution Approach 2:
The patent changes the parameter of data period length based on signal polarity. By setting different data period lengths for positive and negative polarity signals (with positive polarity receiving extended time), the system compensates for the reduced charging rate caused by increased wiring resistance and capacitance in high-resolution large-screen displays
2Reliability
If polarity inversion drive is performed to avoid liquid crystal deterioration, then liquid crystal longevity is improved, but non-uniform transmittance and flicker occur due to insufficient charging of positive polarity pixels
Solution Approach 1:
The patent introduces dynamic adjustment of the data period based on signal polarity. Pixels receiving positive polarity signals are given an extended data period while those receiving negative polarity signals have a shortened period, creating a dynamic timing scheme that compensates for the charging imbalance and eliminates transmittance non-uniformity and flicker while maintaining polarity inversion drive
Solution Approach 2:
The patent applies asymmetry by treating positive and negative polarity signals differently in terms of data period allocation. Instead of symmetric treatment, positive polarity pixels receive longer charging time while negative polarity pixels receive shorter time, creating an asymmetric timing scheme that balances the overall charging rates and eliminates display defects
3Productivity
If the data period is shortened to increase scanning speed, then the scanning efficiency is improved, but the pixel charging completeness deteriorates
Solution Approach 1:
The patent makes the data period dynamic rather than fixed, extending it for positive polarity pixels and shortening it for negative polarity pixels. This dynamic adjustment ensures that despite the overall shortened data period for high scanning efficiency, each pixel group receives adequate charging time to achieve complete charging and eliminate display defects
Data Source
AI summary
Display apparatuses, data drivers and display controller are provided. The data drivers receive video signals, generate positive-polarity and negative-polarity gradation data signals with respect to a predetermined reference voltage based on the video signals, output the positive-polarity gradation data signals to one of a first and a second data line groups, and output the negative-polarity gradation data signals to the other data line group. The data drivers generate, as the positive-polarity gradation data signals, signals in which data pulses each having a positive-polarity analog voltage value corresponding to a luminance level of each pixel based on the video signal appear in predetermined cycles, and generate, as the negative-polarity gradation data signals, signals where data pulses each having a negative-polarity analog voltage value corresponding to a luminance level of each pixel appear in each predetermined cycle with phases different from the positive-polarity gradation data signals.