Eyeball Distance Calculation Using Dual Cornea Reflection Centers
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Solution Overview
Problem
Existing line-of-sight detection devices require complex configurations using ultrasound sensors, stereo cameras, or lens focus systems to calculate the distance between an imaging unit and a subject, complicating the system design.
Innovation Solution
A distance calculation device and method utilizing two light sources emitting detection light from different positions, capturing images of the eyeball to calculate cornea reflection centers, and determining the object distance based on the center-center distance and cornea curvature radius.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If ultrasound sensors, stereo cameras, or lens focus systems are used to detect distance, then distance measurement capability is achieved, but device complexity increases
Solution Approach 1:
The patent introduces cornea reflection centers as an intermediary element. By detecting the positions of cornea reflection centers from multiple light sources and calculating the center-center distance, the system derives object distance without requiring complex distance sensing hardware. The cornea reflection centers serve as a natural mediator that translates optical information into distance measurements.
Solution Approach 2:
The patent replaces mechanical/optical distance sensing systems (ultrasound sensors, stereo cameras, lens focus systems) with a computational geometry approach. Instead of using physical sensors to measure distance directly, the system uses image processing to detect cornea reflection positions and calculates distance through geometric relationships, substituting mechanical measurement with optical-computational methods.
2Measurement precision
If multiple light sources at different positions are used, then distance calculation accuracy is improved, but device complexity increases
Solution Approach 1:
The patent makes the light sources multi-functional. The same light sources that illuminate the subject for imaging purposes also serve as detection light sources for creating cornea reflection centers. This eliminates the need for separate distance sensing light sources, as the imaging light sources perform dual functions: illumination and distance measurement reference.
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
Enables distance calculation between an imaging unit and a subject with a simple configuration, improving accuracy and reducing complexity compared to existing methods.
Implementation Method 1
a first light source 21A and a second light source 21B that emit detection light from positions different from each other and that apply the detection light to at least one of eyeballs EB of a subject
Data Source
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AI summary
A distance calculation device includes a first light source and a second light source that emit detection light from positions different from each other and that apply the detection light to at least one of eyeballs of a subject; an imaging unit that captures an image of the eyeball of the subject to which the detection light is applied; a position calculator that, based on the image of the eyeball of the subject that is captured by the imaging unit, calculates each of a position of a first cornea reflection center according to the detection light from the first light source and a position of a second cornea reflection center according to the detection light from the second light source; a center-center distance calculator that calculates a center-center distance between the position of the first cornea reflection center and the second cornea reflection center; and an object distance calculator that, based on the center-center distance and a cornea curvature radius of the eyeball of the subject, calculates an object distance between the imaging unit and the eyeball of the subject.