Eye Tracking Visor Using Reflected Light for Head-Worn Displays
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Solution Overview
Problem
Existing eye-tracking systems for Head Up Displays (HUDs) face challenges such as obscuration of the user's vision due to the placement of camera and light sources, and leakage of infrared illumination, which affects performance and detection accuracy.
Innovation Solution
A display assembly with a partially reflective and transparent surface on a head-worn device, where the display projector provides non-visible illumination and the sensor uses reflected light for eye tracking, allowing the illumination source to be integrated closer to the user's head without interfering with the display, and the sensor is positioned above the field of view to minimize obscuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a camera and light source are positioned in front of the user's face for eye tracking, then eye tracking accuracy is improved, but the user's vision is obscured
Solution Approach 1:
The camera and light source are repositioned from the traditional front-facing position to the side of the visor assembly, utilizing a different spatial dimension. This lateral positioning allows the optical components to capture eye images and provide illumination without blocking the user's forward view through the visor.
Solution Approach 2:
The visor assembly itself serves as an intermediary element that reflects light from the side-mounted light source onto the user's eye and directs the reflected light to the side-mounted camera. This eliminates the need for front-mounted components while maintaining eye tracking functionality.
2Measurement precision
If an IR illumination source is used for eye tracking, then detection accuracy is improved, but the IR light leaks out of the cockpit
Solution Approach 1:
The illumination is directed locally onto the user's eye through the visor's reflective surface, creating a focused illumination zone. The visor acts as a directional reflector that confines the IR light to the eye tracking function rather than allowing it to disperse and leak into the cockpit environment.
Solution Approach 2:
The potential harmful effect of IR light leakage is converted into a beneficial directional reflection. The visor's reflective properties, which could potentially cause unwanted light scattering, are instead utilized to precisely direct IR illumination onto the eye and guide the reflected light to the camera, improving detection accuracy while preventing leakage.
3Adaptability or versatility
If multiple separate components are used for display and eye tracking, then functionality is improved, but device mass and imbalance increase
Solution Approach 1:
The display projector and eye tracking components (light source and camera) are integrated into a single visor assembly. This merging of functions into one unified structure eliminates the need for separate mounting of multiple components, thereby reducing overall device mass and preventing imbalance issues that would arise from distributed component placement.
Solution Approach 2:
The visor assembly is designed as a multi-functional unit that simultaneously provides display projection and eye tracking capabilities. The same structural assembly that displays information to the user also houses the illumination and sensing components for eye tracking, making the system more compact and balanced while maintaining full functionality.
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
This solution enables accurate eye tracking without obstructing the user's view and reduces the mass and imbalance of hardware, providing enhanced comfort and improved detection accuracy by using the visor as a partially reflective surface for both display and eye tracking.
Implementation Method 1
a display projector for projecting light on to the partially reflective surface for reflection by the partially reflective surface towards a wearer of the display assembly
Implementation Method 2
the sensor is aligned to receive light forming an image of at least one eye of the wearer, the light forming the image being reflected by the partially reflective surface towards the sensor
Implementation Method 3
Another such additional feature is the non-visible illumination comprising an Infra Red (IR) output
Data Source
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AI summary
A display assembly (105) for mounting on a head-worn device such as a helmet, and having a partially reflective surface located in a field of view of a user, a display projector (40, 50, 200) for projecting light towards the user via the partially reflective surface, a sensor (60, 210) for use in tracking an eye of the user, and a partially reflective imaging surface (120, 220, 225) located in the field of view. The sensor is aligned to receive light forming an image of an eye reflected by the partially reflective imaging surface, the image being for use in the eye-tracking. By using a reflected image, the camera location can be arranged to improve the potentially conflicting needs of keeping the field of view clear, and of having an image from directly in front of the eye, and of limiting the weight and size and imbalance of the helmet. The visor may be used as the partially reflective surface. IR Illumination may be provided by the display projector.