Eye Tracker Using Collimated Light Beams for Distance-Independent Gaze
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Solution Overview
Problem
Existing eye tracking technologies face challenges in accurately determining gaze direction independently of the distance between the eye and the tracker device, as well as lateral movement and eye size, which limits their portability and flexibility in use.
Innovation Solution
The method employs at least two substantially collimated light beams with different directions to create reflection spots on the eye's surface, which are then used in conjunction with an imaging unit and data processing to determine gaze direction, allowing for accurate tracking regardless of distance or eye movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing eye tracking technologies are used, then gaze direction can be determined, but the determination is dependent on distance between eye and tracker, lateral movement, and eye size
Solution Approach 1:
The patent introduces a new dimension to gaze tracking by using multiple reflection spots created from different light beam directions. Instead of relying on a single reflection point that requires precise distance and alignment, the system uses the spatial relationship between multiple reflection spots to determine gaze direction, making the measurement independent of distance and lateral movement.
Solution Approach 2:
The patent changes the parameters of the light source from a single point source to multiple collimated light beams with different directions. This parameter change creates multiple reflection spots on the cornea, and the system uses the relative positions of these spots to calculate gaze direction, thereby eliminating dependence on distance and eye size variations.
2Measurement precision
If existing eye tracking technologies are used, then gaze direction can be determined, but the device must be fixed to the observer's head
Solution Approach 1:
By transitioning from single-reflection-point tracking to multi-reflection-spot tracking, the system gains dimensional redundancy that allows it to function without being固定在 the head. The multiple reflection spots provide sufficient geometric information to calculate gaze direction regardless of the device's position relative to the eye.
Solution Approach 2:
The eye tracker device becomes more universal and adaptable by not requiring fixed mounting. The multi-beam approach allows the device to accurately track gaze direction whether positioned close to or far from the eye, enabling flexible placement on various surfaces or devices without compromising measurement capability.
3Device complexity
If a single light source is used, then the device structure is simple, but gaze direction determination is dependent on distance and eye position
Solution Approach 1:
The patent adds dimensional information by introducing multiple light beams from different directions. This creates multiple reflection spots whose spatial relationships provide additional geometric constraints, enabling the system to solve for gaze direction without being constrained by distance or lateral position variations.
Solution Approach 2:
The system changes the light source parameters from a single isotropic point source to multiple directional collimated beams. This parameter modification creates a measurement system that is inherently more robust to positional variations, as the relative geometry of multiple reflection spots remains informative even when the device-to-eye distance changes.
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 enables independent determination of gaze direction, allowing the eye tracker to function effectively over a large area without the need for the device to be fixed to the observer's head, enhancing portability and usability.
Implementation Method 1
directing a first substantially collimated light beam towards the eye in order to provide a first reflection spot when light is reflected from the surface of the eye
Data Source
AI summary
Two collimated light beams are directed towards an eye to provide two reflection spots. The collimated light beams are advantageously provided by a diffractive beam expander. The reflection spots and the pupil of the eye are monitored by an imaging unit. The collimated beams are at different angles with respect to the imaging unit. The gaze direction is determined based on the angles, the positions of the reflections spots, and the position of the pupil. Thanks to the use of the two collimated beams, the detected gaze direction is substantially independent of the size of the eye, independent of the lateral position of the eye, and independent of the distance between the imaging unit and the eye. The detected gaze angle may be used for selecting between options displayed by a virtual display.