Asymmetric Lens Optics for Precise Line-of-Sight Detection
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Solution Overview
Problem
Conventional line-of-sight detection devices struggle with low precision in capturing Purkinje images due to improper placement and distribution of light sources around the optical axis, leading to inaccurate line-of-sight detection.
Innovation Solution
A line-of-sight detection device with an optical system that includes a lens with controlled optical aberration, where light from the user's eye is emitted to a light-receiving surface through a first surface with lesser aberration than the surface through which light from the light source enters, and light sources are strategically positioned to maximize density on the opposite side of the sensor, reducing shading by eyelids and improving image capture.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If light sources are disposed circling around an optical axis of a lens system at approximately equal intervals, then the device structure is simple and manufacturing is easy, but the Purkinje image cannot be correctly captured and line-of-sight detection precision deteriorates
Solution Approach 1:
The patent applies local quality by making the light source distribution non-uniform, with higher density on the opposite side of the sensor. This creates different illumination conditions in different regions of the optical path, optimizing Purkinje image capture while maintaining manufacturing feasibility through a systematic arrangement pattern.
Solution Approach 2:
The patent implements asymmetry by deliberately positioning light sources with higher density on the opposite side of the sensor rather than distributing them uniformly. This asymmetric arrangement compensates for shading effects and improves Purkinje image capture, directly addressing the precision problem while maintaining structural simplicity.
2Measurement precision
If light sources are positioned to maximize density on the opposite side of the sensor, then Purkinje image capture precision is improved, but the device structure becomes more complex
Solution Approach 1:
The patent applies local quality by making the light source distribution non-uniform, with higher density on the opposite side of the sensor. This creates different illumination conditions in different regions of the optical path, optimizing Purkinje image capture while maintaining manufacturing feasibility through a systematic arrangement pattern.
3Measurement precision
If a lens with asymmetric optical aberration is used, then line-of-sight detection precision is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies parameter changes by deliberately designing the lens with different optical aberration characteristics on different surfaces. The first surface has smaller optical aberration to maintain image quality for light from the user's eye, while the second surface has larger optical aberration that is acceptable since it only affects light from the light source. This asymmetric parameter design achieves high precision while relaxing manufacturing constraints.
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
The device achieves high-precision line-of-sight detection by ensuring accurate capture of Purkinje images, even in varying user positions and eye movements, without increasing device size.
Implementation Method 1
a lens having a first surface from which light from the user side is emitted to a light-receiving surface of an image sensor, and a second surface through which light from a light source enters
Implementation Method 2
The light from the light source is mirror-reflected on the surface of the cornea, and is captured as a corneal reflex image, that is, a Purkinje image, on the image acquired by the line-of-sight sensor
Data Source
AI summary
A line-of-sight detection device according to the present invention includes: a display element; an optical system configured to guide light from the display element to a user; a light source; an image sensor configured to capture light from the light source reflected by an eye of the user, through at least a part of the optical system, wherein the optical system includes a lens that has a first surface from which light from the user side is emitted to a light-receiving surface of the image sensor, and a second surface through which light from the light source enters, the lens is disposed at a position facing the image sensor and the light source, and optical aberration of the first surface is smaller than optical aberration of the second surface.