Optical Functional Film Refractive Index Gradient
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Solution Overview
Problem
Existing antireflection films face challenges in achieving low wavelength dependency of transmittance, high optical transparency, and excellent heat and chemical resistance, particularly when applied to large-area displays and light-emitting devices, due to limitations in refractive index gradient formation and multilayer complexity.
Innovation Solution
The development of an optical functional film using a siliceous material composed of polysiloxanes with different refractive indices, formed through a method involving a first layer coating, insolubilizing treatment, and a second layer coating followed by heating, where the refractive index gradually decreases from one surface to the other, eliminating interfaces and reducing reflections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a multilayered antireflection film with optimized refractive indices is used, then reflectance is reduced, but the structure becomes complex and manufacturing precision requirements increase
Solution Approach 1:
The patent divides the antireflection film into multiple layers with different refractive indices (first layer with higher refractive index, second layer with lower refractive index). Each layer is designed with specific thickness and refractive index characteristics to progressively reduce reflectance at each interface, thereby achieving overall low reflectance while maintaining manageable structural complexity through systematic segmentation.
Solution Approach 2:
Different regions of the film structure are assigned different local properties: the first layer near the substrate has higher refractive index to match the substrate, while the second outer layer has lower refractive index to match air. This local quality variation optimizes optical matching at each interface independently, reducing overall reflectance without requiring excessive layer complexity.
2Ease of manufacture
If conventional coating methods are used, then film formation is achieved, but productivity is low and application to large areas is difficult
Solution Approach 1:
The patent employs a sol-gel process where the coating composition undergoes self-hydrolysis and self-condensation of alkoxy groups to form the film structure. This self-service mechanism eliminates the need for complex post-coating processing steps, enabling direct film formation upon coating followed by simple heating treatment, thereby significantly improving productivity and ease of manufacture.
3Ease of manufacture
If a single-layer antireflection film is used, then manufacturing is simple, but wavelength dependency of transmittance increases
Solution Approach 1:
The patent segments the single-layer film into two distinct layers with different refractive indices and thicknesses. The first layer (higher refractive index) and second layer (lower refractive index) work together through optical interference to broaden the effective antireflection bandwidth, thereby reducing wavelength dependency of transmittance while maintaining relatively simple manufacturing through sequential coating and single heating treatment.
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 film achieves high optical transparency, low wavelength dependency, and excellent heat and chemical resistance, making it suitable for large-area applications with improved productivity and versatility as an antireflection film or protective layer.
Implementation Method 1
The refractive index n 2, which is most suitable for the antireflection film under the above-described conditions, is shown as follows: For example, a layer having a very low refractive index such as 1.22 is required between air layer and glass. Furthermore, the film thickness of a layer having a low refractive index layer is λ/4 (λ is here a wavelength of incident light) to make the reflected lights respectively of the layer having a low refractive index and the layer having a high refractive index in the reverse phase each other
Implementation Method 2
a heating step of heating to cure the first layer and the second layer, wherein the curing temperature is 150°C or higher
Data Source
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AI summary
[Problem] To provide an optical functional film having less light reflection and having less wavelength dependency of transmittance, and a method for manufacturing the same. [Means for Solution] An optical functional film, wherein a refractive index nΑ of one surface A of the optical functional film to light is larger than a refractive index nB of the other side surface B to light, and the refractive indices to light decreases gradually from the surface A to the surface B. The optical functional film can be manufactured by conducting multi-layer coating using compositions comprising two kinds of polysiloxane and of solvent on a substrate, compatibilizing the contacting parts of two layers, and thereafter heating them to cure.