Eye Tracking Visor Using Interleaved IR Illumination
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Solution Overview
Problem
Existing eye-tracking systems for Head Up Displays (HUDs) face challenges with illumination and camera placement, which obstruct the user's vision and allow IR leakage, necessitating a solution that does not interfere with the display and maintains unobstructed vision.
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 for eye tracking, interleaved with the display output, and a sensor aligned to receive reflected light from the partially reflective surface, allowing for accurate eye tracking without obstructing the user's view.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a camera and IR light source are positioned in front of the user's face for eye tracking, then eye tracking performance is improved, but the user's vision is obstructed and IR light leaks out of the cockpit
Solution Approach 1:
The patent repositions the eye tracking camera and IR light source from a frontal location to a location above the user's head, utilizing the vertical dimension to avoid obstructing the user's forward vision while maintaining effective eye tracking capability
Solution Approach 2:
The patent introduces a reflective surface (such as a mirror or transparent reflective panel) as an intermediary to redirect the IR light from the source above the head down to the user's eye, and simultaneously reflect the eye image back to the camera, enabling eye tracking without direct line-of-sight components blocking vision
2Measurement precision
If a separate IR illumination source is added to the display system, then eye tracking capability is improved, but device complexity and mass increase
Solution Approach 1:
The patent designs the display projector to serve dual functions: projecting the main display image and providing IR illumination for eye tracking. The same optical components (projector, reflective surface, camera) are utilized for both display and eye tracking operations, eliminating the need for separate dedicated IR illumination hardware
Solution Approach 2:
The patent merges the IR illumination function with the display projection function by integrating the IR light source into the display projector assembly and using the same optical path and reflective surfaces for both purposes, thereby reducing overall system complexity and mass
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 interfering with the display, reduces hardware mass and imbalance, and maintains unobstructed user vision, improving comfort and accuracy by using the visor as a reflective surface for both display and illumination paths.
Implementation Method 1
a partially reflective and transparent surface located in a field of view of a user of the device, and 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 pupil absorbs IR wavelengths and hence appears dark, whereas the sclera reflects IR wavelengths and thus appears bright
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.