Angular Selective Film Using Anisotropic Polymer Layers
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Solution Overview
Problem
Existing technologies lack effective solutions for selectively transmitting or blocking light based on its incidence angle, leading to inefficiencies in light management, particularly in applications where normal incident light needs to pass through while light at larger angles is blocked.
Innovation Solution
An angular selective film is developed using a multilayer structure of isotropic and anisotropic polymer layers with specific refractive index properties, where the film is designed to have higher transmittance for radiation within a specified incidence angle range and lower transmittance for angles outside this range, achieved through the combination of materials like Polyethylene and Polyvinylidene fluoride, with controlled layer thickness and orientation processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional film structure is used, then manufacturing is simple, but angular selectivity for light transmission is not achieved
Solution Approach 1:
The film is divided into multiple alternating layers of isotropic polymer material and anisotropic polymer material. Each layer has a thickness of 1-100 micrometers, creating a segmented structure that enables angular selectivity through the cumulative optical effect of multiple interfaces between layers with different refractive indices.
Solution Approach 2:
The invention uses composite materials consisting of isotropic polymer material (such as polyethylene, polypropylene, or polystyrene) and anisotropic polymer material (such as polyvinylidene fluoride or polyvinyl fluoride). The combination of materials with different optical properties (refractive indices) creates the angular selective transmission effect while maintaining manufacturability through coextrusion processes.
2Reliability
If the film blocks light at larger angles, then angular selectivity is improved, but light transmission at normal incidence may be affected
Solution Approach 1:
The invention optimizes specific parameters including layer thickness (1-100 micrometers for each layer), total film thickness, and the refractive index difference between isotropic and anisotropic layers. By carefully controlling these parameters, the film achieves high angular selectivity (blocking light at angles greater than 30 degrees) while maintaining high transmission (greater than 90%) for normal incident light.
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 effectively transmits light with a normal incident angle without significant loss while blocking light with angles greater than 30°, demonstrating improved angular selectivity and light management capabilities.
Implementation Method 1
The first and second polymer layers have at least one of the following properties: (i) the first polymer layer is isotropic, the second polymer layer is anisotropic, the refractive indices of the first and second polymer layers are substantially the same in a first direction, and the refractive indices of the first and second polymer layers are different in a second direction
Implementation Method 2
the first polymer layer is isotropic, the second polymer layer is anisotropic
Data Source
AI summary
An angular selective film is configured to have a higher transmittance for radiation having an incidence angle in a specified range as compared to radiation having an incidence angle outside of the specified range, and includes a plurality of multilayer modules stacked substantially along a normal direction of the angular selective film. Each multilayer module includes at least first and second polymer layers, which have at least one of the following properties: (i) the first polymer layer is isotropic, the second polymer layer is anisotropic, the refractive indices of the first and second polymer layers are substantially the same in a first direction, and are different in a second direction, or (ii) both the first and second polymer layers are anisotropic, the refractive indices of the first and second layers are substantially the same in a first direction, and are different in the second direction.