Light Guiding Apparatus with Segmented Gratings for Luminance Efficiency
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Solution Overview
Problem
Existing light guiding apparatuses in augmented reality systems lack sufficient luminance efficiency concerning light from the light source.
Innovation Solution
A light guiding apparatus with a light guiding substrate featuring a light receiving unit divided into first and second one-dimensional diffraction gratings, each with a specific area distribution and direction changing units, and a two-dimensional diffraction grating light emitting unit, where the center of the first unit is farther from the light emitting unit than the second, optimizing light path and incorporating a stray light prevention mechanism.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a conventional light guiding apparatus uses a simple light receiving unit without divided diffraction gratings, then the device complexity is low, but the luminance efficiency is insufficient
Solution Approach 1:
The light receiving unit is divided into multiple regions: a first light receiving region with a first one-dimensional diffraction grating, a second light receiving region with a second one-dimensional diffraction grating, and a third light receiving region without a diffraction grating. This segmentation allows different portions of the light receiving unit to handle different light paths optimally, improving overall luminance efficiency while managing device complexity through functional specialization.
Solution Approach 2:
Different regions of the light receiving unit are assigned different optical properties: the first and second regions use diffraction gratings for specific light path control, while the third region uses total internal reflection. This local differentiation optimizes light efficiency for each region's specific function, addressing the luminance efficiency problem without uniformly increasing complexity across the entire device.
2Illumination intensity
If the light receiving unit is divided into multiple units with different diffraction gratings, then the luminance efficiency is improved, but the manufacturing precision requirements increase
Solution Approach 1:
The light receiving unit is segmented into distinct regions with different diffraction grating configurations. The first unit has a first one-dimensional diffraction grating, the second unit has a second one-dimensional diffraction grating with a different groove direction, and the third unit has no diffraction grating. This segmentation allows for modular manufacturing and assembly, managing precision requirements by treating each segment as a separate manufacturing unit.
Solution Approach 2:
The first and second one-dimensional diffraction gratings are designed with asymmetric properties: they have different groove directions relative to the light emitting unit. This asymmetric design optimizes light path separation and combining efficiency, achieving high luminance efficiency while the asymmetric structure itself provides clear manufacturing guidelines that can simplify the precision requirements compared to symmetric designs.
3Illumination intensity
If light paths from different diffraction gratings are optimized separately, then the luminance efficiency is improved, but stray light increases
Solution Approach 1:
The patent converts the potential harmful effect of stray light into a beneficial feature by designing the third light receiving region without a diffraction grating to use total internal reflection. This region specifically handles light that would otherwise become stray light, redirecting it usefully to the light emitting unit. The different groove directions in the first and second diffraction gratings also help confine light paths, reducing stray light generation while maintaining high luminance efficiency.
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
Enhances light efficiency by flexibly dividing the light receiving unit and effectively preventing stray light, resulting in improved luminance efficiency.
Implementation Method 1
a light guiding substrate that transmits rays of light through total internal reflection
Implementation Method 2
a first unit and a second unit, each of the first unit and the second unit being a one-dimensional diffraction grating provided on a surface of the light guiding substrate, the first unit being configured so as to transmit received rays of light along a first path in the light guiding substrate as a first light beam, and the second unit being configured so as to transmit received rays of light along a second path in the light guiding substrate as a second light beam
Data Source
AI summary
A light guiding apparatus comprising: a light guiding substrate; a light receiving unit including first and second units provided on a surface of the substrate, the first and second units transmitting received rays along first and second paths in the substrate as first and second light beams, respectively; a first direction changing unit for the first light beam; a second direction changing unit for the second light beam; and a light emitting unit receiving the first and the second light beams, combining the beams for emission and provided on the surface, wherein on the surface the center of the minimum circle encompassing the first unit is located farther away from the light emitting unit than the center of the minimum circle encompassing the second unit and the first path runs through the portion of the substrate on which the second unit is provided.