Liquid Crystal Display Output Angle Control for Contrast
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Solution Overview
Problem
Liquid crystal display devices suffer from reduced contrast ratio when viewed diagonally due to light leakage, which is exacerbated by the use of light diffusion films that scatter light both forward and sideways, leading to grayscale inversion and limited view angles.
Innovation Solution
A liquid crystal display device configuration that includes a liquid crystal panel with polarizing layers, a lighting device with a light guide, and an output angle control member featuring light diffusion units and shielding units, where the azimuth angle of minimal light intensity matches the narrow view angle direction, and the light scattering is isotropic to minimize diagonal light leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a light diffusion film is provided on the viewing side of the liquid crystal panel, then view angle is widened, but contrast ratio is lowered due to light leakage in the front direction
Solution Approach 1:
The patent divides the light diffusion function into two separate components: a light diffusion film for wide-angle viewing and an output angle control member with light shielding units for controlling diagonal light leakage. This segmentation allows each component to perform its specific function without interfering with the other, resolving the contradiction between view angle and contrast ratio.
Solution Approach 2:
The output angle control member acts as an intermediary between the liquid crystal panel and the viewer. It selectively transmits front-direction light while blocking diagonal light leakage, thereby mediating between the need for wide viewing angle and the need to maintain high contrast ratio by preventing polarizing plate light from leaking diagonally.
2Adaptability or versatility
If light diffusion film scatters light isotropically, then view angle characteristics are improved, but front direction contrast ratio is reduced due to diffusion of leaked light
Solution Approach 1:
The output angle control member implements local quality control by having light shielding units that selectively block light in specific diagonal directions while allowing light transmission in the front direction. This localized control prevents the uniform diffusion of leaked light, maintaining high contrast ratio in the front view while preserving wide viewing angle characteristics.
3Illumination intensity
If the azimuth angle direction of minimal light intensity does not match the narrow view angle direction, then light leakage occurs in the diagonal direction, but matching them reduces overall light output
Solution Approach 1:
The patent converts the harmful effect of directional light leakage into a beneficial feature by intentionally aligning the minimal light intensity direction of the backlight with the narrow view angle direction of the liquid crystal panel. This alignment causes the backlight's naturally low-intensity directions to coincide with the directions where the liquid crystal panel already has limited viewing angle, thereby reducing overall light leakage without requiring additional light blocking.
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 grayscale inversion and enhances view angle characteristics by controlling light output angles and scattering patterns, ensuring better contrast and visibility from various angles.
Implementation Method 1
an output angle control member which is arranged on the light output side of the liquid crystal panel and controls an output angle of light which is output from the liquid crystal panel
Implementation Method 2
a pair of polarizing layers which are arranged on a light input side and a light output side of the liquid crystal layer
Implementation Method 3
Birefringence of liquid crystal molecules changes according to a transmission direction of light
Data Source
AI summary
A liquid crystal display device includes a liquid crystal panel, a pair of polarizing layers, a lighting device, and an output angle control member. The liquid crystal panel includes a pair of substrates, and a liquid crystal layer. The liquid crystal layer is interposed between the pair of substrates. The pair of polarizing layers is arranged on a light input side and a light output side of the liquid crystal layer. The lighting device is arranged on the light input side of the liquid crystal panel and radiates light toward the liquid crystal panel. The output angle control member is arranged on the light output side of the liquid crystal panel and controls an output angle of light which is output from the liquid crystal panel. An azimuth angle direction in which a view angle of the liquid crystal panel is relatively narrow and an azimuth angle direction in which an intensity of light which is radiated toward the liquid crystal panel from the lighting device is relatively small approximately match in an azimuth angle direction which is viewed from a direction normal to the liquid crystal panel.