Multilayer Optical Adhesive Without Carrier Film
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Solution Overview
Problem
Structured films for optical applications, typically made on carrier films like polyethylene terephthalate (PET), suffer from unwanted thickness and optical artifacts due to the carrier film, which adds birefringence and degrades transmittance, and there is a need for thinner films that can be adhered to displays without these issues.
Innovation Solution
A multilayer optical adhesive is developed, comprising a first viscoelastic or elastomeric adhesive layer, a crosslinked or soluble resin layer, and a second viscoelastic or elastomeric adhesive layer, with structured interfaces to achieve desired optical effects, such as refraction or diffraction, without the need for a carrier film, using viscoelastic or elastomeric adhesives and crosslinked or soluble resins with specific refractive indices and interfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a carrier film (PET) is used to make structured films self-supporting, then the structured film can be handled and adhered to displays, but the film thickness increases and optical artifacts (birefringence, reduced transmittance) are produced
Solution Approach 1:
The patent divides the structured film into multiple thin layers (adhesive layer, optically clear layer, structured interface) rather than using a single thick carrier film. This segmentation allows each layer to be thin and transparent while collectively providing the necessary structural support and optical functions without the harmful effects of a thick PET carrier film.
Solution Approach 2:
The patent uses a composite structure combining different materials with specific properties: a viscoelastic adhesive layer for bonding, an optically clear layer for light transmission, and a structured interface for optical effects. This composite approach replaces the单一 PET carrier film with a multi-material system that achieves self-supporting capability without the optical artifacts of traditional carrier films.
2Reliability
If a carrier film (PET) is used to make structured films self-supporting, then the structured film can be handled and adhered to displays, but optical artifacts (birefringence) are produced
Solution Approach 1:
The patent extracts and removes the PET carrier film from the structure, eliminating the source of birefringence. Instead of using PET as the base material, the invention creates a self-supporting structure using thin adhesive and optically clear layers with a structured interface, thereby taking out the harmful element (PET carrier film) while retaining the necessary functional properties.
Solution Approach 2:
The patent applies local quality by creating a structured interface with specific optical properties at the boundary between layers, while keeping the bulk materials optically clear and isotropic. This localized structuring provides the necessary mechanical support and optical effects without introducing birefringence throughout the entire film structure.
3Reliability
If a carrier film (PET) is used to make structured films self-supporting, then the structured film can be handled and adhered to displays, but transmittance is degraded
Solution Approach 1:
The patent segments the film structure into multiple thin transparent layers instead of using a single thick PET carrier film. Each thin layer contributes minimally to light absorption and scattering, allowing the cumulative structure to maintain high transmittance while providing sufficient mechanical support for handling and adhesion.
Solution Approach 2:
The patent changes the material parameters by selecting optically clear materials with high transmittance properties for the adhesive and optically clear layers, rather than using the inherently lower-transmittance PET carrier film. This parameter change in material selection and layer thickness optimizes light transmission while maintaining structural integrity.
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 solution results in thinner, optically clear films with reduced sparkle and glare in displays, providing effective diffraction and refraction without the optical artifacts associated with carrier films, while maintaining high transmittance and stability.
Implementation Method 1
The first viscoelastic or elastomeric adhesive layer has a first refractive index and the first crosslinked or soluble resin layer has a second refractive index different from the first refractive index
Implementation Method 2
A first interface between the first viscoelastic or elastomeric adhesive layer and the first crosslinked or soluble resin layer is structured
Data Source
AI summary
A multilayer optical adhesive including a first viscoelastic or elastomeric adhesive layer and a second viscoelastic or elastomeric adhesive layer. A crosslinked or soluble resin layer may be disposed between the first viscoelastic or elastomeric adhesive layer and the second viscoelastic or elastomeric adhesive layer or the first viscoelastic or elastomeric adhesive layer may be immediately adjacent to the second viscoelastic or elastomeric adhesive layer. An interface between immediately adjacent layers is structured and there is a difference in refractive indices across the interface.