Waveguide Edge Light Shielding Composition Adhesion
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Solution Overview
Problem
Conventional methods for light-shielding waveguide edges in wearable augmented reality devices face challenges in achieving precise and thin coatings, particularly on curved or inclined surfaces, leading to light leakage and external light interference, which affect image quality.
Innovation Solution
A UV curable composition comprising a colorant, acrylate monomer, urethane acrylate oligomer, organosilane, and photopolymerization initiator is used to form a light-shielding film with excellent adhesion and optical density, suitable for application on waveguide edges, utilizing inkjet printing for precise coating and UV curing for effective light-shielding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional contact printing methods are used to coat the waveguide edge, then the coating process is simple, but the manufacturing precision and coating uniformity deteriorate due to inability to precisely coat narrow curved or inclined surfaces
Solution Approach 1:
The patent replaces conventional contact printing methods (screen printing, contact printing) with inkjet printing technology. This substitution enables non-contact deposition of the light-shielding composition, allowing precise coating on narrow curved or inclined waveguide surfaces while maintaining process simplicity. The inkjet system deposits material drop-by-drop under computer control, achieving both ease of manufacture and high manufacturing precision.
Solution Approach 2:
The patent modifies the coating method by changing from contact-based to non-contact inkjet printing. This parameter change in the deposition process enables precise control of coating width (several hundreds of nanometers to several hundreds of microns) and thickness (several micrometers) while adapting to complex waveguide geometries including curved and inclined surfaces.
2Object-affected harmful factors
If the light-shielding layer is made thick to ensure light-shielding performance, then the light-shielding effect improves, but the device complexity and difficulty of precise coating increase
Solution Approach 1:
By replacing contact printing with inkjet printing, the system achieves precise thickness control of the light-shielding layer. The inkjet method deposits material in controlled droplets, enabling formation of thin uniform layers (several micrometers) that provide sufficient light-shielding performance without requiring thick coatings, thereby reducing device complexity.
Solution Approach 2:
The patent changes the coating parameters to achieve thin film formation with high precision. The inkjet printing process controls deposition rate, droplet size, and layer thickness to create light-shielding films of several micrometers thickness that effectively block light leakage and external light interference without the complexity of applying and controlling thick coatings.
3Ease of manufacture
If a plastic case or tape is used for light-shielding, then the implementation is simple, but the manufacturing precision and adhesion control deteriorate
Solution Approach 1:
The patent replaces mechanical attachment methods (plastic cases, tapes) with a chemical deposition method (inkjet printing of UV-curable composition). This substitution enables direct coating of the light-shielding layer onto the waveguide surface, achieving precise width control and excellent adhesion through chemical bonding, while maintaining ease of manufacture through automated printing processes.
Solution Approach 2:
The patent uses a composite UV-curable composition containing colorant, oligomer, monomer, and photopolymerization initiator. This composite material system provides both the light-shielding function (through colorant absorption) and strong adhesion (through oligomer- substrate bonding and UV-curing crosslinking), replacing the need for separate adhesive layers or mechanical attachments.
4Volume of moving object
If the light-shielding coating is made thin to reduce device size, then the device compactness improves, but the light-shielding performance deteriorates
Solution Approach 1:
The patent changes the optical properties of the coating material by incorporating high-concentration colorants (optical black pigments) that provide superior light absorption. This parameter change in material composition enables thin films (several micrometers) to achieve high optical density (OD ≥ 1.5) and effective light-shielding performance, preventing light leakage and external light interference while maintaining device compactness.
Solution Approach 2:
The patent employs a composite UV-curable composition with optimized colorant concentration (0.1-15 wt%) dispersed in oligomer and monomer matrix. This composite structure provides high light absorption efficiency in thin layers, achieving both compact device size and effective light-shielding performance simultaneously.
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 effectively prevents light leakage and external light ingress, ensuring improved image quality by forming a thin, hard, and optically dense light-shielding film with excellent adhesion to the waveguide, even on complex surfaces.
Implementation Method 1
a photopolymerization initiator, wherein the acrylate monomer comprises a monofunctional acrylate monomer, a bifunctional acrylate monomer, and a polyfunctional acrylate monomer
Data Source
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AI summary
The present invention relates to: an ultraviolet curable composition for waveguide edge light shielding, comprising a colorant, an acrylate monomer, a urethane acrylate oligomer, an organosilane and a photopolymerization initiator, wherein the adhesiveness to a glass substrate after curing is 5B or greater by a ASTM D3359 standard and/or is 1,500 mN or greater by a microscratch test (MST); and a waveguide manufacturing method for forming a light-shielding film by using the composition.