Video Processing Circuit for Liquid Crystal Reverse Tilt Domain Control
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Solution Overview
Problem
As liquid crystal panels miniaturize and increase in definition, the horizontal electric field between adjacent pixel electrodes becomes significant, leading to alignment defects such as reverse tilt domains, which cause display defects, and existing solutions either decrease the aperture ratio or limit image brightness.
Innovation Solution
A video processing circuit that analyzes video signals to detect boundaries between pixels with different voltage gradations and corrects the applied voltages to adjacent pixels, ensuring that the voltage difference between them is reduced, thereby minimizing the occurrence of reverse tilt domains without altering the panel structure or limiting image brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the pixel pitch is narrowed to achieve miniaturization and higher definition, then the display resolution is improved, but the horizontal electric field between adjacent pixel electrodes becomes significant causing reverse tilt domains and display defects
Solution Approach 1:
The patent applies preliminary anti-action by detecting boundaries between different voltage regions in advance and correcting voltages before displaying the image. The video processing circuit identifies pixels adjacent to boundaries and adjusts their voltages to prevent the horizontal electric field from causing reverse tilt domains, thereby preventing display defects before they occur.
Solution Approach 2:
The patent changes the voltage parameter of pixels adjacent to boundaries between different voltage regions. The video processing circuit modifies the voltage applied to these specific pixels, creating a gradual transition zone that reduces the horizontal electric field strength and prevents reverse tilt domains while maintaining the narrowed pixel pitch for high definition display.
2Object-affected harmful factors
If a new liquid crystal panel structure with light shielding layer conforming to pixel electrode is designed, then reverse tilt domain is reduced, but the aperture ratio decreases
Solution Approach 1:
The patent replaces the mechanical/structural approach (light shielding layer conforming to pixel electrode) with an electronic processing approach (video signal processing). Instead of physically modifying the liquid crystal panel structure, the video processing circuit electronically adjusts voltages to reduce reverse tilt domains, thereby maintaining the original aperture ratio while achieving the same protective effect.
3Object-affected harmful factors
If video signals with luminance value equal to or higher than a preset value are clipped away, then reverse tilt domain is reduced, but the brightness of displayed images is limited to the preset value
Solution Approach 1:
The patent applies local quality by selectively correcting voltages only for pixels adjacent to boundaries between different voltage regions, rather than uniformly clipping all high luminance values. This localized approach reduces reverse tilt domains at critical boundary areas while preserving the original brightness characteristics of the overall image, avoiding the limitation imposed by global clipping.
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 prevents reverse tilt domains without decreasing the aperture ratio or limiting image brightness, allowing for improved display quality on existing liquid crystal panels.
Implementation Method 1
When a voltage corresponding to a gradation level is applied and held between the pixel electrode and the common electrode, the alignment state of the liquid crystal is defined for each pixel, whereby transmittance or reflectance is controlled
Implementation Method 2
a liquid crystal is interposed between the pixel electrodes and the common electrode
Implementation Method 3
the effect of an electric field which is generated between the adjacent pixel electrodes, namely an electric field in the direction parallel (horizontal) to the substrate surface has become unignorable
Data Source
AI summary
A video processing circuit used in a liquid crystal panel, includes: a first boundary detector that analyzes a video signal of a present frame to detect a boundary between a first pixel and a second pixel; a second boundary detector that analyzes a video signal of a frame one frame before the present frame to detect a boundary between the first pixel and the second pixel; a correction portion that corrects an applied voltage to a liquid crystal device corresponding to a second pixel which is adjacent to a portion of the boundary detected by the first boundary detector, which is changed from the boundary detected by the second boundary detector from the applied voltage specified by the video signal of the present frame to a voltage equal to or higher than the first voltage and lower than the second voltage.