Dual Reflective Facet Waveguide for Eyewear Displays
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Solution Overview
Problem
Conventional waveguides with reflective facets in eyewear displays suffer from diminished optical performance due to discontinuities in the virtual image caused by gaps between adjacent reflective facets, resulting from rounded edges and draft angles during the molding process.
Innovation Solution
A dual reflective facet configuration is implemented, where two sets of reflective facets are arranged alternately to receive light from different directions and redirect it towards a common direction, filling in gaps and improving optical performance by minimizing discontinuities in the outcoupled light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional single-set reflective facets are used in the waveguide, then the device complexity is low and manufacturing is easier, but gaps between adjacent facets cause discontinuities in the virtual image and diminished optical performance
Solution Approach 1:
The reflective facet structure is segmented into multiple sets (first set and second set) with different orientations. Each set is positioned at specific angles to reflect light from different directions, allowing the system to eliminate gaps by distributing reflective functions across multiple segmented facets rather than relying on a single continuous facet that would require perfect manufacturing precision.
Solution Approach 2:
The patent employs asymmetric arrangement of reflective facets where the first set and second set have different angular orientations relative to the waveguide surfaces. This asymmetric configuration allows light from different directions to be reflected toward a common direction, compensating for gaps that would exist in symmetric single-set configurations and improving image uniformity.
2Ease of manufacture
If molded plastic substrates with rounded edges and draft angles are used, then the ease of manufacture is improved, but gaps are created between adjacent reflective facets resulting in image discontinuities
Solution Approach 1:
The patent transitions from a single-plane reflective facet arrangement to a multi-dimensional configuration where facets are arranged at different angular dimensions. By positioning the first set of reflective facets at a first angle and the second set at a second angle, the system creates overlapping light paths that fill gaps caused by manufacturing tolerances in molded substrates, effectively using angular dimensionality to compensate for physical gaps.
Solution Approach 2:
The patent changes the angular parameters of reflective facet orientations to optimize light reflection paths. By adjusting the angles of the first and second sets of reflective facets, the system compensates for gaps introduced by draft angles and rounded edges in molded substrates, transforming the optical path parameters to achieve continuous image coverage despite manufacturing limitations.
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 dual reflective facet configuration enhances the uniformity and quality of the virtual image delivered to the user by reducing or eliminating gaps in the outcoupled light, thereby improving the overall optical performance of the eyewear display.
Implementation Method 1
two sets of reflective facets are arranged alternately to receive light from different directions and redirect it towards a common direction
Implementation Method 2
the incoupled display light beams are 'guided' through the waveguide, typically by multiple instances of total internal reflection (TIR)
Data Source
AI summary
A waveguide includes an outcoupler with a dual reflective facet configuration. The dual reflective facet configuration includes a first set of reflective facets to receive light from a first direction and reflect the light incident thereon to an outcoupling direction. The dual reflective facet configuration also includes a second set of reflective facets to receive light from a second direction and reflect the light incident thereon to the outcoupling direction.