Diffractive Light Guide Design to Prevent AR Display Darkening
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Solution Overview
Problem
The center of a display range in augmented reality systems can become dark or invisible due to the reduction of light entering the eyes, causing issues with visibility and image quality.
Innovation Solution
A light guide device with a light guide system that includes first and second diffraction elements, where the elements have varying refractive index differences and thicknesses to optimize light reflection and diffraction, ensuring light is efficiently guided to the eyeballs and preventing darkening at the center of the display range.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a light guide device uses a virtual image optical system to improve contrast and light use efficiency, then light guiding performance is improved, but the center of the display range becomes dark or invisible
Solution Approach 1:
The optical element is divided into multiple diffraction elements (first diffraction element and second diffraction element) with different functions. The first diffraction element handles light at specific angles while the second diffraction element handles light at other angles, allowing independent optimization of each region's light guiding performance and preventing darkening at the center of the display range.
Solution Approach 2:
Different regions of the optical element are assigned different properties through the use of multiple diffraction elements with different refractive index differences and thicknesses. This allows the center region to maintain brightness while peripheral regions benefit from improved light guiding, creating non-uniform but optimized local characteristics across the display range.
2Productivity
If diffraction elements have large refractive index difference and thickness to improve diffraction efficiency, then light guiding is enhanced, but manufacturing complexity increases
Solution Approach 1:
The optical element is segmented into multiple diffraction elements with different refractive index differences and thicknesses. This segmentation allows each element to be optimized for specific light angles while maintaining manufacturability through standardized fabrication processes for each segment, rather than requiring a single complex element.
Solution Approach 2:
The patent optimizes the refractive index difference and thickness parameters of each diffraction element to achieve high diffraction efficiency. By carefully selecting and varying these parameters across different elements, the system achieves high productivity while keeping manufacturing within feasible limits through controlled parameter variation rather than extreme values.
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 suppresses darkening and invisibility at the center of the display field by enhancing light diffraction efficiency and ensuring consistent illumination across the entire field of view, improving image clarity and visibility.
Implementation Method 1
light emitted from the light source device and projected to the first diffraction element at a predetermined incident angle is reflected and diffracted at the first diffraction element
Implementation Method 2
light emitted from the light source device and projected to the first diffraction element at a predetermined incident angle is reflected and diffracted at the first diffraction element
Implementation Method 3
the light transmitted through the first diffraction element is reflected and diffracted at the second diffraction element
Implementation Method 4
the second diffraction element has a lens function
Data Source
AI summary
Provided is a light guide device that can suppress darkening and invisibleness at the center of a display range. A light guide device according to the present technique includes a light guide system that guides light emitted from a light source device to eyeballs, wherein the light guide system has an optical element including first and second diffraction elements that are opposed to each other, light emitted from the light source device and projected to the first diffraction element at a predetermined incident angle is reflected and diffracted at the first diffraction element, the light reflected and diffracted at the first diffraction element is reflected and diffracted at the second diffraction element, the light that is reflected and diffracted at the second diffraction element and is transmitted through the first diffraction element is guided to the eyeballs, the second diffraction element has a lens function, and the first and second diffraction elements vary in refractive index difference and thickness.