Infrared Illuminator Lightguide for Compact Eye Tracking
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Solution Overview
Problem
Integrating eye tracking with wearable heads-up displays poses a challenge in placing light sources to illuminate the eye with infrared light without making the device bulky and interfering with image projection.
Innovation Solution
An apparatus featuring a support frame with a lightguide that circumscribes the lens periphery, incorporating outcoupling elements to direct infrared light efficiently towards the eye, while maintaining a compact design and allowing for image projection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If light sources are placed to illuminate the eye with infrared light, then eye tracking functionality is achieved, but the device becomes bulky
Solution Approach 1:
The lightguide is positioned within the frame structure, nesting the illumination system within the existing device boundaries. The lightguide circumscribes the lens periphery, effectively utilizing the space around the existing optical components without adding external bulk to the device.
Solution Approach 2:
The illumination is distributed along the length of the lightguide rather than from a single point source, spreading the light-emitting elements across multiple positions. This dimensional distribution allows efficient eye tracking illumination while maintaining a compact overall device structure.
2Reliability
If light sources are placed to illuminate the eye, then eye tracking is enabled, but image projection is interfered with
Solution Approach 1:
The lightguide and outcoupling elements are positioned specifically at the periphery of the lens, concentrating the illumination function in a localized region. This peripheral placement allows the central lens area to remain clear for image projection, enabling both eye tracking and display functionality without mutual interference.
Solution Approach 2:
The illumination system is segmented into multiple outcoupling elements spaced along the lightguide length, with each element directing light at specific positions. This segmentation allows precise control of illumination zones, separating the eye tracking illumination path from the image projection path through the lens.
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
Enables effective eye tracking without bulkiness, allowing for precise gaze position determination and efficient power management by illuminating the eye with infrared light while maintaining the display functionality.
Implementation Method 1
The lightguide circumscribes at least a portion of the periphery of the lens and has an input end to receive light and a length along which the received light propagates
Implementation Method 2
The outcoupling elements are spaced out along the length of the lightguide and optically coupled to the lightguide. The outcoupling elements couple light out of the lightguide at respective positions along the length of the lightguide
Data Source
AI summary
An apparatus to illuminate a target includes a lens having a lens side to be positioned in opposing relation to the target. The apparatus includes a lightguide that circumscribes at least a portion of the periphery of the lens. The lightguide has an input end to receive light and a length along which the receive light propagates. The apparatus includes outcoupling elements that are spaced out along the length of the lightguide. The outcoupling elements couple light out of the lightguide at respective positions along the length of the lightguide. The outcoupling elements are oriented to direct the outcoupled light towards the target when the lens side is positioned in opposing relation to the target. An eye tracking apparatus including the illumination apparatus and a method of eye tracking are disclosed.