Eye Tracking Optical System with Dynamic Imaging Properties
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Solution Overview
Problem
Existing eye tracking devices face challenges in achieving high precision and accuracy due to limitations in determining eye features like pupil and cornea reflections, especially in varying user positions and lighting conditions, leading to difficulties in integrating them into compact devices such as head-mounted displays.
Innovation Solution
The eye tracking device employs an optical system with different imaging properties, allowing for flexible adaptation by varying focal lengths, image planes, and aperture settings, enabling the capture of both sharp and unsharp images to accurately determine eye features, and utilizing these differences to enhance gaze direction calculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed focus lens with fixed depth of field is used, then the device structure is simple, but the image quality deteriorates when user position varies
Solution Approach 1:
The patent applies dynamics by making the optical system adjustable between different imaging modes. The lens can switch between a first imaging mode (with first imaging properties) and a second imaging mode (with second imaging properties), allowing the system to adapt to varying user positions and lighting conditions, thereby maintaining high measurement precision without excessive structural complexity.
Solution Approach 2:
The patent changes imaging parameters by switching between different imaging modes with distinct properties. The optical system can alter focal length, aperture size, and depth of field parameters dynamically, enabling optimal image capture for eye feature determination under different conditions while managing device complexity.
2Stability of the object's composition
If aperture is made small to increase depth of field, then depth of field increases, but light intensity decreases
Solution Approach 1:
The aperture size is made dynamic rather than fixed. The optical system can adjust aperture size between different imaging modes, allowing it to have a small aperture when large depth of field is needed and a large aperture when high light intensity is required, thus resolving the contradiction between these two parameters.
Solution Approach 2:
The patent changes the aperture parameter dynamically by switching imaging modes. In the first imaging mode, the aperture may be smaller to provide larger depth of field, while in the second imaging mode, the aperture opens larger to increase light intensity for image capturing, optimizing both parameters under different operating conditions.
3Measurement precision
If multiple imaging properties are provided, then accuracy and precision improve, but device complexity increases
Solution Approach 1:
The optical system is designed with multi-functionality, where a single imaging unit can operate in multiple imaging modes with different imaging properties. This universal design allows the system to achieve high measurement precision through parameter variation without requiring multiple separate imaging devices, thus managing device complexity.
Solution Approach 2:
The imaging properties are made dynamic through the ability to switch between different imaging modes. The optical system can change focal length, aperture, and depth of field parameters on demand, providing multiple imaging properties temporally rather than requiring all properties simultaneously in space, thereby improving accuracy without proportionally increasing device complexity.
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 significantly improves the precision and accuracy of eye tracking by allowing larger apertures for higher light intensity, reducing image quality issues, and enabling accurate determination of eye features even in challenging conditions, while also facilitating compact integration into various devices.
Implementation Method 1
the capturing unit is configured to capture a first image and a second image of the at least one part of the at least one eye of the user... the capturing unit captures the first image by capturing light that has passed along the first optical path and the second image by capturing light that has passed along the second optical path
Data Source
AI summary
The invention relates to an eye tracking device (10a; 10b; 10c) comprising a processing unit (18) and an optical system (14), which comprises a capturing unit. The optical system (14) provides a first optical path (P; P1) with a first imaging property and a second optical path (P; P2) with a second imaging property and the capturing unit (C; C1, C2) captures a first image (24a) by capturing light that has passed along the first optical path (P; P1) and a second image (24b) by capturing light that has passed along the second optical path (P; P2), so that due to the difference of the first and second imaging property the first (24a) and the second image (24b) comprise a difference related to a characteristic of at least part of the first and the second image (24b), wherein the eye tracking device (10a; 10b; 10c) is configured to determine a property of the eye (12) on the basis of at least one of the first image (24a) and the second image (24b).