Waveguide-Based Illumination for Lightweight AR Eye Tracking
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Solution Overview
Problem
Existing augmented reality (AR) technologies face challenges in providing comfortable and natural-feeling presentations of virtual image elements due to aesthetically undesirable physical LEDs for IR eye tracking, which impose mechanical constraints and result in sub-optimal performance.
Innovation Solution
A head-mounted display system with a frame, image projector, illumination source, light-guiding component, and diffusive optical elements is configured to project light to the user's eye, utilizing components like prisms and waveguides to efficiently illuminate the eye without significantly increasing system mass, power, or cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If physical LEDs are used for IR eye tracking illumination, then eye tracking function is achieved, but aesthetic appearance deteriorates and mechanical placement constraints increase
Solution Approach 1:
A light-guiding component (waveguide) is introduced as an intermediary between the illumination source and the user's eye. The waveguide receives IR light from the illumination source and guides it to illuminate the user's eye, eliminating the need for direct LED placement near the eye. This resolves the mechanical placement constraints while maintaining eye tracking performance.
Solution Approach 2:
The patent replaces the direct mechanical placement of physical LEDs near the eye with an optical guidance system using waveguides. This substitution eliminates rigid mechanical mounting requirements and allows for more flexible, aesthetically pleasing device design while maintaining the eye tracking function.
2Reliability
If illumination components are added to the head-mounted display system, then eye tracking capability is improved, but system mass increases
Solution Approach 1:
The light-guiding component serves multiple functions: it guides IR illumination light for eye tracking, transmits visible light for the augmented reality display, and can be integrated into the existing head-mounted display structure. This multi-functionality adds eye tracking capability without requiring separate dedicated components that would increase mass.
Solution Approach 2:
The illumination source and light-guiding component are integrated into the existing head-mounted display system structure. The waveguide is combined with the display optics, and the illumination source is merged with other system components, thereby adding eye tracking functionality while minimizing additional mass.
3Reliability
If illumination components are added to the head-mounted display system, then eye tracking capability is improved, but system volume increases
Solution Approach 1:
The light-guiding component is implemented as a thin waveguide structure that can be integrated into the head-mounted display without significantly increasing volume. The waveguide uses total internal reflection to guide light through a thin substrate, maintaining a compact form factor while enabling eye tracking illumination.
4Illumination intensity
If physical LEDs are positioned near the user's eye, then illumination effectiveness is improved, but aesthetic appearance deteriorates
Solution Approach 1:
The waveguide acts as an intermediary that allows the illumination source to be positioned away from the user's eye while still delivering effective illumination. The light-guiding component transports IR light over a distance and delivers it to the eye region, maintaining illumination effectiveness while enabling aesthetically pleasing device design.
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 system effectively projects AR content while maintaining a lightweight and efficient design, allowing for comfortable and natural integration of virtual elements with the real world.
Implementation Method 1
a light-guiding component, said light-guiding component configured so as to be positioned forward one of the user's eyes when the frame is worn by the user
Implementation Method 2
at least one diffusive optical element disposed on the light-guiding component so as to be positioned forward one of the user's eyes when the frame is worn by the user, wherein the at least one diffusive optical element is configured to diffusively couple light from the at least one illumination source out of the light-guiding component
Data Source
AI summary
A head-mounted display system is configured to project light to an eye of a user wearing the head-mounted display system to display content in a vision field of said user. The head-mounted display system comprises at least one diffusive optical element, at least one out-coupling optical element, at least one mask comprising at least one mask opening, at least one illumination in-coupling optical element configured to in-couple light from at least one illumination source into a light-guiding component, an image projector configured to in-couple an image and an at least one illumination source is configured to in-couple light into at least one illumination in-coupling optical element, an eyepiece, a curved light-guiding component, a light-guiding component comprising a portion of a frame, and/or two light-guiding components disposed on opposite sides of at least one out-coupling optical element.