AR Lightguide Polymer-Embedded Reflectors Without Adhesive Lamination
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Solution Overview
Problem
Existing methods for manufacturing lightguides with internal partially reflecting surfaces in visual augmented reality devices are suboptimal due to complexity, material waste, high cost, and susceptibility to delamination under bending forces.
Innovation Solution
A lightguide design featuring a glass substrate with a polymer layer and internal partial reflectors, where the reflectors are encapsulated within the polymer layer, eliminating the need for adhesives and ensuring mechanical robustness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If glass plates with reflective surfaces are laminated together with adhesive and then sliced at an angle to form lightguide, then internal partially reflecting surfaces are achieved, but the manufacturing process becomes complex, time-consuming, and generates material waste
Solution Approach 1:
The patent segments the manufacturing process into distinct stages: forming the polymer layer with sawtooth structures first, then adding reflective coatings to specific surfaces. This segmentation allows each component to be optimized independently and assembled without requiring complex lamination and slicing operations, thereby reducing manufacturing complexity while maintaining precision of internal reflecting surfaces
Solution Approach 2:
Instead of creating flat glass plates with reflective surfaces and then slicing them at angles, the patent inverts the approach by first creating the angled sawtooth structures in the polymer layer, then applying reflective coatings. This inversion eliminates the need for precision slicing and lamination, significantly simplifying the manufacturing process while achieving the same optical function
2Manufacturing precision
If glass plates are laminated with adhesive to form stacked structure, then internal reflecting surfaces are created, but the lightguide becomes susceptible to delamination under bending forces
Solution Approach 1:
The patent merges the substrate material and the reflecting surface into a single integrated structure. The reflective coatings are applied directly to the sawtooth surfaces of the polymer layer, creating a unified component rather than separate laminated layers. This integration eliminates adhesive interfaces that would be prone to delamination, significantly improving reliability under bending forces while maintaining the precision of internal reflecting surfaces
Solution Approach 2:
The patent uses composite material construction where a polymer layer is combined with reflective coatings (such as metal or dielectric layers) to create a new material system with both structural integrity and optical functionality. This composite approach provides mechanical robustness comparable to glass while eliminating the delamination issues inherent in laminated glass structures
3Ease of manufacture
If sawtooth shaped transparent forms are injection-molded or cast, then the lightguide structure is formed, but material choice is limited and high-index glass cannot be used
Solution Approach 1:
The patent changes the material parameter from glass to polymer, which fundamentally alters the manufacturing capabilities. Polymers can be injection-molded or cast into complex sawtooth shapes more easily than glass, expanding manufacturing ease. Simultaneously, this material change enables the use of various polymer types with different optical properties, actually increasing material versatility rather than limiting it, as polymers offer a broader range of可调 parameters including refractive index, flexibility, and weight
4Manufacturing precision
If two sawtooth forms are ground and polished as exact negatives, then precise fitting is achieved, but the process becomes extremely difficult and time-consuming
Solution Approach 1:
The patent replaces the mechanical grinding and polishing process with injection-molding or casting techniques. These processes use mold cavities to directly form the sawtooth shapes, eliminating the need for precision mechanical removal of material. This substitution dramatically increases productivity while maintaining or even improving manufacturing precision through the accuracy of the mold cavities
Solution Approach 2:
The patent performs preliminary action by creating precise mold cavities before the actual lightguide formation. The mold cavities are prepared in advance with the exact negative geometry needed, so that when polymer is injected or cast, the correct sawtooth shapes are formed automatically. This preliminary preparation of molds eliminates the need for time-consuming post-processing grinding and polishing operations
5Ease of manufacture
If adhesive is used to sandwich reflective portions between transparent pieces, then assembly is achieved, but additional expense and complexity are added
Solution Approach 1:
The patent merges the assembly process into a single injection-molding or casting operation where the polymer layer, sawtooth structures, and encapsulation are formed simultaneously. This eliminates the separate steps of placing reflective portions, applying adhesive, and assembling multiple pieces, thereby reducing both the number of manufacturing steps and the associated complexity and expense
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 design reduces manufacturing complexity, minimizes material waste, and enhances mechanical durability while maintaining optical performance.
Implementation Method 1
a polymer layer on the glass substrate
Implementation Method 2
partial reflectors disposed within the polymer layer, the partial reflectors disposed at an oblique angle relative to the first primary glass surface
Implementation Method 3
The transparent component typically transmits the computer-generated imagery to the eyes of the user via internal reflection
Data Source
AI summary
A lightguide for a visual augmented reality device includes: (a) a glass substrate having a first glass primary surface, a second glass primary surface, and a glass thickness, the first glass primary surface and the second glass primary surface facing in generally opposite directions; (b) an encapsulating polymer layer disposed on the first glass primary surface, the encapsulating polymer layer including a first polymer primary surface, a second polymer primary surface facing the first glass primary surface, and a polymer thickness between the first polymer primary surface and the second polymer primary surface, the first polymer primary surface and the second polymer primary surface facing in generally opposite directions; and (c) partial reflectors disposed within the polymer thickness, the partial reflectors disposed at an oblique angle relative to the first primary glass surface. The glass substrate is free of adhesive disposed within the glass thickness.