Liquid Crystal Driving Unit Voltage Correction for Alignment Defects
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Liquid crystal panels experience alignment defects due to transverse electric fields, leading to defective displays, particularly when a constant correction voltage is applied across all pixels in a frame, causing noticeable changes in transmittance.
Innovation Solution
A driving unit for liquid crystal devices is designed to generate and apply specific voltages to adjacent pixels based on their grayscales, with varying voltage periods to minimize the transverse electric field and reduce reverse tilt domains by adjusting the correction voltage dynamically, focusing on pixels with detected risk boundaries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a constant correction voltage is applied to a pixel throughout the entire frame period, then the alignment defect (reverse tilt domain) is suppressed, but the change in transmittance becomes large and easily noticeable to users
Solution Approach 1:
The patent applies periodic action by dividing the frame period into multiple sub-periods and alternating between applying correction voltage and normal voltage. Specifically, during odd-numbered sub-periods, correction voltage is applied to suppress alignment defects, while during even-numbered sub-periods, normal voltage is applied to minimize transmittance changes. This periodic switching maintains alignment defect suppression effectiveness while reducing the cumulative transmittance change that would be noticeable to users.
Solution Approach 2:
The patent implements dynamics by making the correction voltage application timing adaptive rather than static. The driving unit determines the optimal timing for applying correction voltage based on the actual display requirements and frame structure. By dynamically adjusting when correction voltage is applied (only during specific sub-periods rather than continuously), the system optimizes between alignment defect suppression and minimizing visible transmittance changes.
2Reliability
If correction voltage is applied to all pixels uniformly, then alignment defects are suppressed across the display, but the complexity of voltage control increases
Solution Approach 1:
The patent applies local quality by differentiating the voltage control strategy based on pixel location and characteristics. The driving unit identifies pixels that are more prone to alignment defects (such as those at specific positions or with certain grayscale values) and applies correction voltage selectively to these pixels during odd-numbered sub-periods, while other pixels receive normal voltage control. This localized approach maintains alignment defect suppression effectiveness while reducing the overall complexity of voltage control compared to uniformly applying correction voltage to all pixels.
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 reverse tilt domains and suppresses changes in transmittance, minimizing the occurrence of defective displays and making them less noticeable to users, while allowing for uniform correction across complex display patterns.
Implementation Method 1
a liquid crystal element which is interposed between the pixel electrode and the common electrode... a change in transmittance of a liquid crystal element due to an application of a correction voltage
Implementation Method 2
an alignment defect in the liquid crystal (reverse tilt domains) due to a transverse electric field which is generated between pixel electrodes which are adjacent to each other
Data Source
AI summary
A video processing circuit includes a boundary detection unit which detects a boundary between a first pixel in which an application voltage which is designated by a video signal Vid-in is lower than a first voltage and a second pixel which exceeds a second voltage in which the application voltage is higher than the first voltage in a normally black mode; and a correction unit which corrects a video signal in which an application voltage to a liquid crystal element corresponding to the first pixel which comes into contact with a boundary detected by the boundary detection unit is designated to be a video signal in which a correction voltage which is higher than the application voltage is designated in a part of period of one frame period, and a correction voltage which is lower than the application voltage is designated in other periods of the one frame period.