Liquid Crystal Display Sub-Pixel Voltage Control for Gamma Consistency
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Solution Overview
Problem
Conventional liquid crystal display devices, particularly those using MVA and ASM modes, suffer from significant viewing angle dependence of the gamma characteristic, leading to poor contrast and grayscale inversion when viewed from oblique angles, making it difficult to produce high contrast panels with high productivity.
Innovation Solution
A liquid crystal display device with a liquid crystal layer divided into pixels, each comprising sub-pixels that apply distinct voltages to improve gamma characteristics, where the voltage difference between sub-pixels is adjusted based on grayscale levels to maintain optimal contrast across different viewing angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If MVA or ASM mode is used to improve viewing angle characteristics, then contrast and grayscale display are improved, but gamma characteristic dependence on viewing angle becomes more obvious
Solution Approach 1:
The pixel electrode is divided into multiple sub-pixel electrodes (first sub-pixel electrode, second sub-pixel electrode, third sub-pixel electrode) with different orientations. Each sub-pixel electrode applies voltage to control liquid crystal molecules in specific regions, allowing independent control of light transmission in different viewing direction ranges to achieve consistent gamma characteristics across viewing angles
Solution Approach 2:
Different sub-pixel electrodes are assigned to control different viewing angle ranges. The first sub-pixel electrode controls a first range of viewing angles, the second sub-pixel electrode controls a second range of viewing angles, and the third sub-pixel electrode controls a third range of viewing angles. This local control approach ensures that each viewing angle range receives optimized voltage control for consistent gamma characteristics
2Productivity
If TN mode is used to achieve high productivity and production margin, then manufacturing efficiency is improved, but viewing angle characteristic and contrast drop significantly when viewed from oblique direction
Solution Approach 1:
The pixel electrode is divided into multiple sub-pixel electrodes with different orientations (first sub-pixel electrode, second sub-pixel electrode, third sub-pixel electrode). Each sub-pixel electrode controls liquid crystal molecules in different regions, enabling the display to maintain high contrast when viewed from oblique directions while preserving the manufacturing efficiency of TN mode
Solution Approach 2:
The invention introduces orientation as an additional control dimension by tilting the liquid crystal molecules at specific angles (e.g., 45 degrees) relative to the substrate plane in addition to the in-plane switching mechanism. This multi-dimensional control enables oblique viewing performance improvement without sacrificing productivity
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
The solution enhances the gamma characteristic of liquid crystal display devices, improving display quality and contrast consistency across various viewing angles by dynamically adjusting voltage differences between sub-pixels based on grayscale levels, thereby addressing the limitations of MVA and ASM modes.
Implementation Method 1
A conventional twisted neumatic (TN) liquid crystal display device can arrange the long axis of the liquid crystal molecules with a positive dielectric rate and an anisotropy substantially parallel to the substrate surface, and carry the orientation processing, so that the long axis of the liquid crystal molecules can be twisted for substantially 90 degrees between the upper and lower substrates and along the thicknesswise direction of the liquid crystal layer
Implementation Method 2
If a voltage is applied to the liquid crystal layer, the liquid crystal molecules are resumed to be parallel to the electric field to release the twisted orientation
Implementation Method 3
The TN liquid crystal display device can control the transmittance by using the liquid crystal molecules according to the optical property of the orientation change of the voltage
Data Source
AI summary
A liquid crystal display device includes a liquid crystal layer which is divided into a plurality of pixels having a plurality of electrodes applying a voltage to the liquid crystal layer. Each pixel includes a first sub-pixel and a second sub-pixel. When each pixel displays a grayscale gk, the voltages applied to the liquid crystal layer of the first sub-pixel and second sub-pixel of each pixel are V1(gk) and V2(gk), and ΔV12(gk)=V1(gk)−V2(gk) is set, where 0≤gk≤n, and gk and n are integers greater than 0, and n represents the highest-brightness grayscale. When the grayscale gk is smaller than a predetermined grayscale gs, ΔV12(gk)>0V is set, and the relation ΔV12(gk)>ΔV12(gk+1) is satisfied. When the grayscale gk is equal to or greater than the predetermined grayscale gs, ΔV12(gk)=0V is set, and the relation ΔV12(gk)=ΔV12(gk+1) is satisfied.