Optical Waveguide Support Layer to Prevent Grating Collapse
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Solution Overview
Problem
The rigidity of optical waveguides in augmented reality display apparatuses decreases due to thinning of glass cover plates and waveguides, leading to grating collapse under external forces, affecting performance.
Innovation Solution
Incorporating a support layer between the substrate and protective layer in the optical waveguide, with a thickness greater than the grating, to absorb external forces and prevent grating collapse, enhancing structural support and extending the waveguide's lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the glass cover plate and optical waveguide are thinned to reduce weight and improve wearing experience, then the weight and comfort are improved, but the rigidity decreases causing the grating structure to collapse under external force
Solution Approach 1:
The patent applies composite materials by combining the substrate, grating structure, adhesive layer, and protective layer into a multi-layer composite structure. This composite design allows each layer to contribute specific properties - the substrate provides base strength, the grating enables optical functionality, the adhesive layer adds structural reinforcement, and the protective layer provides surface durability, collectively achieving both weight reduction and sufficient rigidity
Solution Approach 2:
The patent introduces a new dimensional element by adding the adhesive layer as a separate structural component between the substrate and protective layer. This additional layer creates a distributed support structure that prevents direct contact between the protective layer and grating, thereby preventing collapse while maintaining the thin-profile design
2Illumination intensity
If the glass cover plate is thinned to improve transparency and reduce weight, then light transmittance and weight are improved, but the protective capability decreases allowing the grating to collapse
Solution Approach 1:
The adhesive layer serves as an intermediary element between the protective layer and the grating structure. It mediates the mechanical stress distribution, preventing the protective layer from directly pressing against and collapsing the grating while still allowing the thin protective layer to provide adequate protection and maintain high light transmittance
3Length of moving object
If the adhesive layer is made thinner to reduce overall thickness, then the compactness is improved, but the bonding strength and structural support decrease
Solution Approach 1:
The patent optimizes the adhesive layer thickness to a specific parameter range that balances bonding strength and overall compactness. By precisely controlling the adhesive layer thickness and selecting appropriate adhesive materials with high bond strength, the design achieves sufficient structural support while maintaining the thin-profile requirement for wearable applications
Data Source
AI summary
An optical waveguide, a method for manufacturing the same, and an augmented reality display device. The optical waveguide includes: a substrate; a grating being arranged on a surface of the substrate and being located in a first region; a support layer being arranged on the surface of the substrate and being located in at least portion of a second region, and the surface of the support layer away from the substrate not being lower than the surface of the grating away from the substrate; an adhesive layer being located in a third region; and a protective layer being connected to the substrate through the adhesive layer, the grating, the support layer and the bonding layer are all located between the substrate and the protective layer.