Video Processing Circuit for LCD Transverse Electric Field Reduction
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Solution Overview
Problem
In liquid crystal display panels, the narrow pixel pitch leads to a transverse electric field that causes orientation errors in liquid crystal molecules, resulting in display defects like reverse tilt domains, which existing solutions either reduce aperture ratio or limit image brightness.
Innovation Solution
A video processing circuit that detects boundaries between pixels with different voltage levels and corrects the voltage applied to adjacent pixels to reduce the transverse electric field, thereby minimizing reverse tilt domains without altering the panel structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the pixel pitch is narrowed for miniaturization and high precision, then the display resolution is improved, but a transverse electric field is generated between adjacent pixel electrodes causing reverse tilt domains and display defects
Solution Approach 1:
The patent applies preliminary anti-action by detecting boundaries between different gray scale regions in advance and preemptively correcting the video signal at these boundaries. The correction is applied before the image is displayed, preventing the transverse electric field from causing reverse tilt domains. This is achieved by identifying boundary pixels and adjusting their voltage levels to reduce the electric field strength at critical interfaces between different gray scale regions.
Solution Approach 2:
The patent changes the voltage parameter of pixels at boundary locations to reduce the transverse electric field. By detecting boundary pixels between different gray scale regions and adjusting their voltage levels (either increasing or decreasing based on the specific boundary condition), the patent modifies the electric field distribution to prevent reverse tilt domains while maintaining overall image quality.
2Object-affected harmful factors
If a light blocking layer structure is contrived to reduce reverse tilt domain, then the display defect is reduced, but the aperture ratio is decreased
Solution Approach 1:
The patent replaces the mechanical/structural approach (light blocking layer) with a signal processing approach (video signal correction). Instead of physically modifying the liquid crystal display panel structure to reduce reverse tilt domains, the patent processes the video signal to adjust voltage levels at boundary pixels, thereby reducing the transverse electric field's harmful effects without any structural changes.
Solution Approach 2:
The patent introduces a video processing circuit as an intermediary between the image source and the liquid crystal display panel. This intermediary processes the video signal to detect boundary pixels and apply corrections that reduce the transverse electric field, thereby eliminating the need for structural modifications like light blocking layers while maintaining display quality.
3Object-affected harmful factors
If the video signal is clipped to reduce reverse tilt domain, then the display defect is reduced, but the image brightness is indiscriminately limited
Solution Approach 1:
The patent applies local quality by making corrections only at boundary pixels between different gray scale regions, rather than applying uniform clipping across the entire image. This localized correction approach reduces the transverse electric field at critical interfaces while preserving the brightness and quality of the rest of the image, avoiding the indiscriminate brightness limitation caused by global signal clipping.
Solution Approach 2:
The patent applies partial action by correcting only the necessary boundary pixels that contribute to reverse tilt domains, rather than applying excessive clipping to the entire video signal. This selective correction maintains overall image brightness and quality while sufficiently reducing the transverse electric field effects at problem areas.
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 suppresses reverse tilt domains without reducing aperture ratio or limiting image brightness, making it applicable to existing liquid crystal display panels.
Implementation Method 1
only a component in a direction from the pixel electrodes to the common electrode (or in a reverse direction), that is, in a direction perpendicular to a substrate surface (longitudinal direction), within an electric field acting on liquid crystal molecules, contributes to a display control
Implementation Method 2
an orientation state of the liquid crystal is regulated for each pixel, and thus transmittance or reflectance is controlled
Implementation Method 3
an electric field has been generated between adjacent pixel electrodes, that is, in a direction parallel to a substrate surface (transverse direction), the affect of which cannot be neglected
Implementation Method 4
an orientation error of the liquid crystal (reverse tilt domain) occurs, thereby causing a display defect
Data Source
AI summary
A video processing includes: a boundary detecting section which respectively detects, in a current frame and a previous frame, a boundary between a first pixel in which the applied voltage designated by the video signal is lower than a first voltage and a second pixel in which the applied voltage is equal to or higher than a second voltage which is higher than the first voltage; and a correcting section which corrects the voltage applied to the liquid crystal element corresponding to at least one of the first pixel and the second pixel in positions between which a portion which moves from the boundary of the previous frame by one pixel is interposed, within the boundary of the current frame, to correct the input video signal in a direction where a transverse electric field generated in the first pixel and the second pixel is reduced.