Liquid Crystal Display Black Level Suppression via Asymmetric Light Distribution
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Solution Overview
Problem
Conventional liquid crystal display devices in IPS and FFS modes face challenges in achieving balanced view angle characteristics, particularly with high black level luminance in specific directions due to unconsidered scattering leakage light, leading to distorted contrast ratios.
Innovation Solution
The implementation of a liquid crystal display device configuration with a light source having a wider light distribution in the left-and-right direction, a liquid crystal panel with a biaxial retardation film, and strategically oriented polarizers and analyzers to align absorption axes, along with belt-shaped electrodes, which helps in reducing black level luminance by managing diffraction and scattering leakage light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional liquid crystal display device uses a light source with narrow light distribution, then the device structure is simple, but the black level luminance in specific directions (upper left and upper right) becomes high, degrading contrast ratio
Solution Approach 1:
The patent applies local quality by designing a light source with non-uniform light distribution characteristics - specifically wider light distribution in the left-and-right direction and narrower distribution in the up-and-down direction. This localized optimization of light distribution patterns selectively reduces black level luminance in the upper left and upper right directions while maintaining simplicity in the overall device structure, avoiding the need for complex additional optical components.
2Reliability
If the liquid crystal molecules have pretilt angle to control orientation, then the liquid crystal layer achieves proper switching, but the view angle characteristic becomes distorted due to polarization cancellation effects
Solution Approach 1:
The patent applies asymmetry by configuring the liquid crystal molecules with a pretilt angle in a specific direction (left-and-right direction) rather than uniform orientation. This asymmetric pretilt configuration, combined with the asymmetric light source distribution, creates an asymmetric optical system that compensates for polarization cancellation effects in specific viewing directions, thereby improving view angle characteristics while maintaining reliable switching performance.
3Object-generated harmful factors
If the light source has wider light distribution in left-and-right direction, then scattering leakage light is reduced, but the light distribution control becomes more difficult
Solution Approach 1:
The patent applies parameter changes by optimizing the light distribution characteristics of the light source - specifically adjusting the width of light distribution in the left-and-right direction while maintaining narrower distribution in the up-and-down direction. This parameter optimization reduces scattering leakage light without requiring complex control mechanisms, as the improved light distribution is achieved through inherent source design rather than active control systems.
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 configuration effectively suppresses black level luminance in the upper left and upper right directions, improving the balance of contrast ratios and enhancing display quality by minimizing the impact of scattering and diffraction leakage light.
Implementation Method 1
a biaxial retardation film which is arranged between the polarizer and the liquid crystal cell
Implementation Method 2
a polarizer which is arranged on the light source side with respect to the liquid crystal cell and in which an absorption axis is aligned in the up-and-down direction; and an analyzer which is arranged on a side opposite to the light source side with respect to the liquid crystal cell and in which an absorption axis is aligned in the left-and-right direction
Implementation Method 3
liquid crystal molecules sandwiched between the substrates
Data Source
AI summary
Liquid crystal molecules have a pretilt angle to the left-and-right direction in a plane perpendicular to the up-and-down direction, so that an end part of a first side as one side of a left side and a right side of the liquid crystal molecules is set closer to a backlight than an end part of a second side as the other side. Second edge parts of a black matrix adjacent to an upper side and a lower side of an opening have a straight line shape extending by inclination to mutually the same side in the left-and-right direction, so that an end part of the same side as a first side as one side of the left side and the right side of the second edge parts is positioned above the end part of the same side as the second side as the other side.