Optical Film with Dual Diffraction Gratings for LCD Viewing Angle Leakage
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Solution Overview
Problem
Liquid crystal displays (LCDs) suffer from color washout and dark-state light leakage at wide viewing angles due to asymmetry of liquid crystal molecules, leading to varying image quality and contrast when viewed from different angles.
Innovation Solution
An optical film comprising a first diffraction layer with parallel first diffraction gratings, a second diffraction layer with gap-filled second diffraction gratings, and a cover layer containing dyes, where the refractive indices and microstructure dimensions of the layers are optimized to reduce light leakage and enhance image uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional liquid crystal display is used, then the display can show images in front view, but light leakage occurs at wide viewing angles causing color washout and dark-state light leakage
Solution Approach 1:
The optical film is divided into multiple functional layers: a first diffraction layer with first diffraction gratings, a second diffraction layer with second diffraction gratings, and a cover layer with dyes. Each layer segments the light control function, with the diffraction layers directing light at different angles and the dye layer absorbing residual light, collectively solving the wide-angle light leakage problem
Solution Approach 2:
The diffraction gratings in different layers have different orientations and parameters tailored to specific viewing angle requirements. The first diffraction gratings are oriented in one direction while the second diffraction gratings are oriented in another direction, creating localized light control properties for different viewing zones to minimize light leakage at wide angles
2Illumination intensity
If the liquid crystal panel is switched to dark state to shade light, then black color can be displayed, but light leakage still occurs at wide viewing angles causing uneven image quality
Solution Approach 1:
The patent converts the harmful light leakage effect into a beneficial light redirection effect. The diffraction gratings are designed to redirect leaked light away from the viewer's line of sight at wide angles, transforming the problematic light leakage into a controlled light distribution pattern that maintains dark state uniformity
Solution Approach 2:
The optical film uses composite material structure combining diffraction grating patterns in multiple layers with dye materials. The diffraction gratings provide angular light control while the dyes provide broadband light absorption, creating a composite solution that addresses both the brightness and uniformity requirements in dark state
3Object-affected harmful factors
If diffraction gratings are added to control light leakage, then light leakage is reduced, but the device structure becomes more complex
Solution Approach 1:
Multiple diffraction grating layers are merged into a single integrated optical film structure. The first and second diffraction layers are combined with the cover layer in a unified film that can be applied as one component to the display, reducing the overall system complexity despite the sophisticated internal structure
Solution Approach 2:
The patent uses thin film technology to create the multi-layer diffraction structure. The entire optical film including multiple diffraction layers and cover layer is formed as a flexible thin film that can be laminated onto the display surface, maintaining simplicity in integration despite complexity in internal light control mechanisms
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 optical film effectively reduces light leakage and improves the uniformity of dark-state images at wide viewing angles, maintaining good color accuracy and saturation by minimizing dark light leakage across various viewing angles.
Implementation Method 1
a first diffraction layer with a upper surface and a lower surface, including a plurality of first diffraction gratings arranged in the same direction on the upper surface thereof
Implementation Method 2
the first diffraction layer has a first refraction index of n1, the second diffraction layer has a second refraction index of n2, the cover layer has a third refraction index of n3
Implementation Method 3
a cover layer containing dyes formed on the second diffraction gratings of the second diffraction layer
Data Source
AI summary
An optical film includes a first diffraction layer, a second diffraction layer, and a cover layer. The first diffraction layer includes a plurality of first diffraction gratings arranged in the same direction on a surface thereof. The second diffraction layer includes a plurality of second diffraction gratings arranged in the same direction gap-filled the first diffraction gratings of the first diffraction layer, wherein the directions of the first diffraction gratings and the second diffraction gratings are parallel to each other. The cover layer is formed on the second diffraction gratings of the second diffraction layer. At least one of the first diffraction layer, the second diffraction layer and the cover layer contains dyes, and therefore, the optical film can reduce the light leakage defect of a conventional liquid crystal display in a large viewing angles and make the liquid crystal display have uniform dark-state images and colorful images.