Optical Film with Patterned Layers for Display Viewing Angle
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Solution Overview
Problem
Liquid crystal display devices face challenges in maintaining display quality, particularly at front and side viewing angles, due to deterioration in light emission and contrast ratio caused by the viewing angle, which existing optical films fail to adequately address.
Innovation Solution
A display device is designed with an optical film featuring a first pattern layer and a second pattern layer with different refractive indices, where the first pattern layer has a refractive index less than the second, and the protrusions on these layers are optimized in shape and arrangement to enhance light emission and contrast ratio at various viewing angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional optical film is used, then the display device can be manufactured with simple structure, but the display quality deteriorates at side viewing angles due to light emission and contrast ratio deterioration
Solution Approach 1:
The optical film is divided into multiple pattern layers (first pattern layer and second pattern layer) with different refractive indices and distinct protrusion patterns. This segmentation allows each layer to independently control light in specific directions, thereby improving side viewing angle display quality while maintaining manufacturing feasibility through modular layer construction
Solution Approach 2:
Different regions of the optical film are designed with locally optimized properties: the first pattern layer has protrusions optimized for certain viewing angles while the second pattern layer has protrusions optimized for other angles. This local quality differentiation enables comprehensive coverage of various viewing conditions without requiring complete redesign of the entire film structure
2Reliability
If the refractive index difference between pattern layers is increased, then the light control capability improves, but the manufacturing precision requirements increase due to tighter tolerances on protrusion dimensions
Solution Approach 1:
The patent optimizes specific parameters including the refractive index difference (set to 0.05-0.15), protrusion height (5-20 μm), and protrusion pitch (20-50 μm). These parameter ranges are carefully selected to achieve effective light control while maintaining reasonable manufacturing tolerances. The moderate refractive index difference avoids excessive sensitivity to dimensional variations
3Illumination intensity
If the protrusion height and pitch are optimized for front viewing angle, then the front brightness is improved, but the side viewing angle performance deteriorates
Solution Approach 1:
The viewing angle coverage is segmented between two pattern layers: the first pattern layer primarily addresses front viewing angle performance with its protrusion configuration, while the second pattern layer complements it by optimizing side viewing angle performance. This segmentation enables simultaneous satisfaction of multiple viewing angle requirements
Solution Approach 2:
The patent transitions from a single-layer design to a multi-layer vertical structure, adding the dimension of layer stacking. This allows independent optimization of each layer for different viewing angles, effectively expanding the overall viewing angle coverage without compromising front brightness
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 optimized optical film structure improves front brightness and contrast ratio, and reduces gamma distortion index (GDI) values, resulting in superior display quality at both front and side viewing angles.
Implementation Method 1
the optical film including a first pattern layer having a first refractive index and a second pattern layer having a second refractive index different from the first refractive index
Data Source
AI summary
Provided is a display device. The display device includes a liquid crystal display panel and an optical film disposed above the liquid crystal display panel, the optical film comprising a first pattern layer having a first refractive index and a second pattern layer having a second refractive index different from the first refractive index and disposed on the first pattern layer. The first pattern layer includes a first base part and a plurality of first protrusions. Each of the first protrusions includes a bottom surface adjacent to the first base part, an upper surface facing the bottom surface, and side surfaces between the bottom surface and the upper surface. Each of the side surfaces is perpendicular to the bottom surface and the upper surface.