Liquid Crystal Display Two-Line Inversion Write Period Compensation
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Solution Overview
Problem
High-resolution liquid crystal display devices using two-line inversion driving experience image quality degradation due to lateral stripes caused by differences in the effective write period of video signals between adjacent pixel rows, leading to insufficient improvement in image quality with existing precharge voltage techniques.
Innovation Solution
A liquid crystal display device with a display control circuit that performs line inversion driving every two rows by writing display data into the video signal line driver circuit at a higher speed for the preceding scanning row and extending the output period of the preceding scanning row, while reducing the output period of the following scanning row, using an input signal pre-processing circuit to generate modified data enable signals and store data in memory banks to compensate for write time differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If two-line inversion driving is used to reduce power consumption in high-resolution displays, then power consumption is reduced, but image quality deteriorates due to lateral stripes caused by write period differences between adjacent rows
Solution Approach 1:
The patent applies preliminary action by pre-charging video signal lines before writing video signals to pixels. A precharge voltage is applied to the video signal lines in advance of the actual video signal writing operation, ensuring that the lines are ready to receive signals without delay. This precharging mechanism compensates for the capacitance of the video signal lines, reducing the time required for voltage transitions and eliminating the write period differences that cause lateral stripes in two-line inversion driving mode.
2Reliability
If video signal lines are charged and discharged with polarity inversion to implement AC voltage driving, then liquid crystal panel deterioration is suppressed, but power consumption increases
Solution Approach 1:
The patent implements periodic action through N-line inversion driving, where the polarity of video signals is inverted every N rows (with N≥2). This periodic polarity inversion suppresses liquid crystal panel deterioration by preventing DC bias accumulation. By optimizing N to be 2 or more, the patent reduces the frequency of polarity inversions compared to traditional one-line inversion, thereby reducing the charge-discharge operations on video signal lines and lowering power consumption while maintaining panel reliability.
3Manufacturing precision
If write period for preceding scanning row is extended to compensate for voltage arrival delay, then image quality improves, but horizontal scanning period increases
Solution Approach 1:
The patent applies local quality by selectively adjusting the write period only for the preceding scanning row in each pair of rows with the same polarity. The control circuit extends the write period specifically for rows that require compensation for voltage arrival delay, while maintaining the normal write period for other rows. This localized adjustment compensates for the delay in voltage arrival on video signal lines without increasing the overall horizontal scanning period, thus improving image quality without sacrificing scanning speed.
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 the difference in write periods between adjacent rows, eliminating or reducing lateral stripes and improving image quality by ensuring consistent signal delivery across the display screen.
Implementation Method 1
each of the pixel expresses a gradation according to an orientation of liquid crystal molecules which are controlled by a potential difference between the pixel electrode and the common electrode
Implementation Method 2
an AC voltage driving that periodically inverses a polarity of a voltage between the pixel electrode and the common electrode is conducted
Data Source
AI summary
In a liquid crystal display device that performs two-line inversion driving, a difference of a write period of a substantial video signal between a pair of pixel rows scanned with the same polarity is compensated. An input signal pre-processing circuit 42 receives display data DATA and an original data enable signal DTMG, generates and inputs a data enable signal DTMG_R and display data DATA_R to a driver control signal generation block 40. DTMG_R is reduced in the active period, and an interval of the active period between a (2n−1)-th row and a 2n-th row is set to be larger than an interval of the active period between the 2n-th row and a (2n+1)-th row. The input signal pre-processing circuit 42 reads out DATA of each row from a buffer as DATA_R in an active period of DTMG_R.