IR-Waveguide Eye Tracking Module for Unobtrusive Smart Glasses
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Solution Overview
Problem
Integrating eye cameras and IR-illumination means in head-wearable devices, such as spectacles, is challenging due to the need for unobtrusive placement that minimally restricts the user's field of view while being cost-effective and adaptable to various use cases.
Innovation Solution
An eye tracking module with an IR-waveguide that guides IR-light without diverting visible light, allowing a single image sensor to capture multiple regions of interest, including the user's field of view and eyes, and is removably attachable to a head-wearable device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional eye cameras and IR-illumination means are integrated in head-wearable devices, then eye tracking functionality is achieved, but the device becomes bulky and obstructs the user's field of view
Solution Approach 1:
The patent combines the IR-waveguide for eye tracking with the visible light optical path into a single integrated module. The IR-waveguide is positioned such that it does not obstruct the visible light path, allowing both IR eye tracking and visible scene capture to coexist in a compact form factor, eliminating the need for separate bulky camera modules
Solution Approach 2:
The invention utilizes the wavelength dimension by employing an IR-waveguide that is transparent to visible light. This allows the IR optical path and visible light optical path to occupy the same physical space without interference, effectively adding a functional dimension without increasing physical volume
2Measurement precision
If multiple separate cameras are used for eye tracking, then comprehensive eye data is captured, but device complexity and cost increase
Solution Approach 1:
The single image sensor serves multiple functions: it captures visible light from the scene through the optical path, and simultaneously captures IR light reflected from the eyes through the IR-waveguide. This multi-functional design eliminates the need for separate eye cameras while maintaining comprehensive eye tracking capability
Solution Approach 2:
The patent merges the functions of separate eye cameras and scene camera into a single image sensor unit. By combining the IR-waveguide and visible light optical path to converge on the same sensor, the system achieves comprehensive eye tracking and scene capture with reduced component count and simplified architecture
3Measurement precision
If eye cameras are positioned to focus well on eyes, then eye tracking quality improves, but the user's field of view is restricted
Solution Approach 1:
The IR-waveguide is designed with specific local properties: it is opaque to IR light for guiding eye tracking photons, but transparent to visible light for maintaining the user's field of view. This local differentiation of optical properties allows the same component to serve both eye tracking and scene viewing functions without compromise
Solution Approach 2:
The IR-waveguide acts as an intermediary that selectively guides IR light from the eyes to the image sensor while allowing visible light to pass through to the user's eyes. This intermediary structure enables simultaneous optimization of eye tracking quality and field of view by mediating between the two optical paths
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 a compact, unobtrusive, and comfortable design that minimizes field of view occlusion, reduces hardware requirements, and enhances wearing comfort by using a transparent IR-waveguide to integrate eye tracking functionality into head-wearable devices.
Implementation Method 1
an IR-waveguide arranged with respect to the optical path such that received visible light is at least substantially not diverted and/or guided by the IR-waveguide
Implementation Method 2
an IR-waveguide arranged with respect to the optical path such that received visible light is at least substantially not diverted and/or guided by the IR-waveguide
Data Source
AI summary
An eye tracking module for a head-wearable device of a user includes an electronics carrier, an image sensor arranged on the electronics carrier, an optical path for receiving visible light at the image sensor from a first region of interest, and an IR-waveguide arranged with respect to the optical path such that received visible light is at least substantially not diverted and/or guided by the IR-waveguide. The IR-waveguide includes a first input aperture for receiving IR-light from a second region of interest which is different to the first region of interest, and an output aperture for outputting at least a part of the received IR-light towards the image sensor.