Coaxial Eye Tracking Near-Eye Display with Beamsplitter
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Solution Overview
Problem
Conventional head-mounted display systems face challenges in aligning eye imaging and display imaging paths, leading to complex setups and reduced user experience due to separate optical paths for illumination and imaging.
Innovation Solution
A near-eye display device with coaxial eye tracking functionality, utilizing a display unit, a viewing unit, and an eye imaging unit that merges infrared light beams with visible display light to illuminate the eye while allowing ambient light view, and a camera to image the pupil and reflections, forming images indicative of gaze direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate optical paths are used for illumination and imaging, then the system can perform eye tracking and display functions, but the device complexity and alignment difficulty increase
Solution Approach 1:
The patent merges the illumination optical path and imaging optical path into a single coaxial path. The infrared illumination light and visible display light share the same optical axis, allowing the eye imaging unit to capture reflections from the eye while the display unit presents images to the user. This eliminates the need for separate optical paths and reduces alignment complexity.
Solution Approach 2:
The optical path is designed to serve multiple functions simultaneously. The same optical path is used for both displaying visual information to the user and for capturing eye reflections for tracking. The beamsplitter interface enables this multi-functionality by directing different wavelengths (infrared and visible) along the same path while allowing ambient light transmission.
2Ease of operation
If coaxial optical paths are used for illumination and display, then alignment is simplified, but merging multiple light beams requires additional optical components
Solution Approach 1:
The patent introduces a beamsplitter interface as an intermediary component that enables the merging of infrared illumination beams with visible display beams. This beamsplitter is disposed between the display unit and viewing unit, and it selectively directs different wavelengths along the same optical path. The intermediary component simplifies the merging process while maintaining optical precision.
3Productivity
If infrared light beams are merged with visible display light, then eye illumination and display presentation are achieved simultaneously, but the beamsplitter interface adds manufacturing complexity
Solution Approach 1:
The patent utilizes parameter changes in light wavelength to achieve simultaneous illumination and display functions. The beamsplitter interface is designed to differentiate between infrared wavelengths (for eye illumination) and visible wavelengths (for display presentation). By exploiting the wavelength parameter difference, the system can merge these light beams in the same optical path while maintaining distinct functional pathways through spectral separation.
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
Simplifies alignment of eye imaging with display imaging, enhancing user experience by allowing control through gaze direction and enabling biometric identification and health parameter assessment.
Implementation Method 1
an illumination module for generating at least three infrared light beams propagating along at least three different, non-coplanar directions, respectively
Implementation Method 2
a first beamsplitter interface, disposed between the display unit and the viewing unit, for merging at least a portion of each of the infrared light beams with the visible light to direct each portion toward the eye via the viewing unit
Implementation Method 3
a camera for imaging, via the viewing unit and the first beamsplitter interface, pupil of the eye and reflections of the infrared light beams incident on the eye, to form one or more images indicative of gaze direction of the eye
Data Source
AI summary
A near-eye display device includes (a) a display unit for displaying a display image, (b) a viewing unit for presenting the display image to the eye and transmitting ambient light from an ambient scene toward the eye, and (c) an eye imaging unit including (i) an illumination module for generating at least three infrared light beams propagating along at least three different, non-coplanar directions, respectively, (ii) a first beamsplitter interface, disposed between the display unit and the viewing unit, for merging at least a portion of each of the infrared light beams with visible display light to direct each portion toward the eye via the viewing unit, and (iii) a camera for imaging, via the viewing unit and the first beamsplitter interface, pupil of the eye and reflections of the infrared light beams incident on the eye, to form one or more images indicative of gaze direction of the eye.