In-Plane Eye Tracking Illumination to Prevent Double Glints
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Solution Overview
Problem
Existing eye tracking systems in near-eye display devices face challenges with illumination efficiency and accuracy due to the presence of corrective optical lenses, which distort light beams and cause issues like double glints and reduced illumination, especially in wearable devices with complex optical assemblies.
Innovation Solution
The use of side- or top-emitting light emitting diodes (LEDs) aligned with the optical assembly plane, combined with refractive or reflective elements, to redirect beams and mitigate distortion caused by corrective lenses, ensuring efficient illumination and accurate eye tracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional illumination systems are used in near-eye display devices, then the system structure is simple, but the illumination efficiency is reduced and eye tracking accuracy deteriorates due to light beam distortion by corrective lenses
Solution Approach 1:
The patent transitions from traditional perpendicular illumination to in-plane illumination, where the light source and detector are positioned within the same plane as the optical assembly. This dimensional change allows light to travel parallel to the corrective lens surface, eliminating distortion and double glint effects while maintaining system simplicity.
Solution Approach 2:
The patent introduces an in-plane light source as an intermediary element that mediates between the eye and the detector. By positioning the light source within the optical assembly plane rather than perpendicular to it, the system achieves accurate eye tracking without the need for complex distortion correction algorithms or additional optical components.
2Use of energy by moving object
If conventional LED illumination is used, then the device structure is simple, but illumination efficiency is reduced due to beam distortion by corrective optical lenses
Solution Approach 1:
The patent repositions the LED illumination from a perpendicular configuration to an in-plane configuration, changing the dimensional relationship between the light source and the corrective lens. This allows light to propagate parallel to the lens surface, avoiding refraction and distortion, thereby maximizing illumination efficiency without adding optical complexity.
Solution Approach 2:
The patent changes the spatial parameters of the illumination system by positioning the LED within the optical assembly plane and adjusting its orientation to emit light parallel to the corrective lens surface. This parameter change eliminates beam distortion and maximizes light utilization efficiency.
3Adaptability or versatility
If illumination beams pass through corrective lenses, then the system can accommodate vision correction, but double glints and reduced illumination occur
Solution Approach 1:
The patent positions both the light source and detector within the same plane as the corrective lens, changing the traditional perpendicular illumination geometry. This in-plane configuration allows the system to accommodate corrective lenses while avoiding beam distortion and double glint effects that plague conventional designs.
Solution Approach 2:
The patent extracts the illumination and detection functions from the traditional perpendicular path and repositions them within the optical assembly plane. This separation allows the system to work around corrective lenses without being disrupted by their optical effects.
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 approach enhances eye tracking accuracy and illumination efficiency while accommodating corrective optical lenses, reducing system complexity and power consumption in near-eye display devices.
Implementation Method 1
side- or top-emitting light emitting diodes (LEDs) aligned with the optical assembly plane
Implementation Method 2
combined with refractive or reflective elements, to redirect beams and mitigate distortion
Implementation Method 3
combined with refractive or reflective elements, to redirect beams and mitigate distortion
Data Source
AI summary
An eye tracking system with in-optical-assembly plane illumination is described. Side-emitting light emitting diodes (LEDs) aligned with a plane of an optical assembly of a near-eye display device are used to illuminate the eye of a user and generate glints that can be detected by an eye tracking camera. A waveguide display of the near-eye display device projects computer-generated content to the eye. A mirror is positioned between the LEDs and the waveguide display to reflect light beams generated from the LEDs toward the waveguide display to mitigate any double glints that may cause ghost signals. A processor of the near-eye display device determines a position and gaze of the eye based on the captured image of the eye with the glints, and generates the computer-generated content for the waveguide display based on the position and gaze of the eye.