Multilayer Laminated Film with Monotonic Optical Thickness
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Solution Overview
Problem
Multilayer laminated films face challenges in achieving high polarization, uniform color, and reduced color distortion when viewed obliquely while maintaining a wide reflection wavelength range, especially with limited layer thickness or weight constraints.
Innovation Solution
A multilayer laminated film structure comprising alternately laminated birefringent and isotropic layers with specific monotonically increasing optical thickness profiles, where the birefringent layers have a first monotonically increasing region with a maximum optical thickness of 100 nm or less and a second region with a minimum optical thickness greater than 100 nm, and the isotropic layers have a second monotonically increasing region with a maximum optical thickness of 200 nm or less, achieving a high degree of polarization and uniform color.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the number of layers is increased to achieve high reflectance over a broad wavelength range, then the reflectance performance is improved, but the film thickness and weight increase
Solution Approach 1:
The patent applies parameter changes by optimizing the optical thickness distribution of individual layers rather than simply increasing the number of layers. Specifically, it controls the monotonic increase of optical thickness in birefringent layers (with slope ratios 1B/1A between 0.8-1.5) and isotropic layers (with slope ratios 2B/2A between 1.5-5), achieving high reflectance across 380-780nm wavelength range with reduced film thickness
Solution Approach 2:
The patent uses composite materials by combining birefringent layers (with refractive index difference ≥0.05) and isotropic layers in an alternating multilayer structure. This composite approach enables optical interference effects that provide high reflectance across broad wavelength ranges without requiring excessive numbers of layers
2Reliability
If the number of layers is increased to achieve high polarization, then the degree of polarization is improved, but the device complexity increases
Solution Approach 1:
The patent achieves high degree of polarization (≥70%) by precisely controlling the optical thickness parameters of birefringent and isotropic layers. The monotonic increase in optical thickness with specific slope ratios creates optimal conditions for polarization through optical interference, achieving high polarization without requiring excessive layer complexity
3Adaptability or versatility
If the film is designed to reflect light in a wide wavelength range, then the reflection wavelength range is improved, but color uniformity deteriorates
Solution Approach 1:
The patent applies local quality by creating different optical thickness regions within the layer structure. The birefringent layers have optical thickness increasing from 100nm or less (region 1A) to more than 100nm (region 1B), while isotropic layers have optical thickness increasing from 200nm or less (region 2A) to more than 200nm (region 2B). This local variation in optical thickness enables wide wavelength reflection while maintaining color uniformity
Solution Approach 2:
The patent controls the slope ratios of optical thickness increase to achieve both wide wavelength range and color uniformity. By maintaining 1B/1A between 0.8-1.5 and 2B/2A between 1.5-5, the film achieves balanced optical interference across the visible spectrum (380-780nm) while minimizing color distortion when viewed from oblique directions
4Length of moving object
If the film thickness is reduced to make the film smaller and lighter, then the weight and size are improved, but the number of layers is limited
Solution Approach 1:
The patent optimizes the optical thickness parameters of each layer to maximize reflection performance within a limited number of layers. The controlled monotonic increase of optical thickness with specific slope ratios enables achieving high reflectance and polarization with fewer layers, reducing both film thickness and weight while maintaining performance
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 a high degree of polarization, uniform color, and reduced color distortion when viewed obliquely, while maintaining a wide reflection wavelength range, without the need for increasing the number of layers or expanding existing equipment.
Implementation Method 1
the multilayer laminated film being capable of reflecting light with a wavelength of 380 to 780 nm due to optical interference caused from the lamination structure of the birefringent layer and the isotropic layer
Implementation Method 2
a birefringent layer comprising a first resin and an isotropic layer comprising a second resin are alternately laminated
Data Source
AI summary
The invention provides a multilayer laminated film with alternately laminated birefringent and isotropic layers. The birefringent layers have a first monotonically increasing region of optical thickness and contain monotonically increasing region 1A of maximum optical thickness is 100 nm or less, and monotonically increasing region 1B of minimum optical thickness of more than 100 nm, and ratio 1B/1A of slope 1B of monotonically increasing region 1B to slope 1A of monotonically increasing region 1A is 0.8 or more and less than 1.5. The isotropic layers have a second monotonically increasing region of optical thickness and contain monotonically increasing region 2A of maximum optical thickness of 200 nm or less and monotonically increasing region 2B of minimum optical thickness of more than 200 nm, and ratio 2B/2A of slope 2B of monotonically increasing region 2B to slope 2A of monotonically increasing region 2A is more than 1.5 and less than 5.