Eye Movement Measurement Apparatus Tremor Detection
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Solution Overview
Problem
Current eye movement measurement technologies face challenges in accurately detecting the tremor component due to its small high-frequency oscillation, and existing methods are either invasive or lack precision for practical patient diagnosis.
Innovation Solution
An eye movement measurement apparatus that images corneal reflection light using a photodetecting section with multiple pixels, calculates the position of the corneal reflection light image, and generates a tremor signal by differencing smoothed and non-smoothed data strings to isolate the tremor component.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a piezoelectric element is pressed against the eye to measure tremor, then measurement capability is achieved, but measurement precision and patient comfort deteriorate due to contact measurement
Solution Approach 1:
The patent replaces the mechanical contact measurement system (piezoelectric element pressed against eye) with an optical non-contact measurement system. The corneal reflection light image is captured by an imaging device, and tremor is detected by analyzing temporal changes in the bright spot position, eliminating the need for physical contact with the eye.
Solution Approach 2:
The patent introduces corneal reflection light as an intermediary to transfer the tremor information from the eye to the imaging device. Instead of directly measuring the eye surface with a sensor, the system captures the reflection of light off the cornea, which moves with the tremor, allowing indirect but accurate measurement without contact.
2Loss of information
If tremor component is removed as noise in eye movement analysis, then low-frequency drift and flick components can be extracted, but information about brain stem function is lost
Solution Approach 1:
The patent extracts the tremor component from the total eye movement signal by calculating the difference between the original position data and the smoothed position data. This allows the tremor information to be separated and analyzed independently, preserving it for brain function assessment while still enabling accurate extraction of drift and flick components when needed.
Solution Approach 2:
The patent segments the eye movement signal into distinct frequency components: tremor (high-frequency), drift (low-frequency), and flick (microsaccade). By applying smoothing to separate the frequency bands and then differencing to isolate tremor, the system can analyze each component independently for different diagnostic purposes.
3Productivity
If high-speed imaging is used to capture tremor oscillation, then measurement speed improves, but device complexity increases
Solution Approach 1:
The patent uses a standard digital imaging device (such as a camera) that can be operated at different frame rates. The same device can capture both high-speed tremor oscillations when needed and perform slower eye movement tracking during other times, making the system versatile without requiring multiple specialized devices.
Solution Approach 2:
The patent creates a digital copy of the corneal reflection light image at high frame rates. Instead of using complex physical measurement devices, the system uses digital image processing to capture and analyze tremor, leveraging software-based analysis to achieve high measurement speeds with relatively simple hardware.
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 accurate detection of the tremor component, improving measurement accuracy and providing a non-contact, high-speed method suitable for health diagnostics.
Implementation Method 1
an imaging section having a photodetecting section including a plurality of pixels arrayed two-dimensionally, for generating imaging data including the corneal reflection light image
Data Source
AI summary
An eye movement measurement apparatus 1 measures movement of a cornea 101 by imaging a corneal reflection light image L2 generated as a result of irradiating the cornea 101 with infrared light L1. The eye movement measurement apparatus 1 includes: an imaging section 5 having a sensor section 51 including a plurality of pixels arrayed two-dimensionally, for generating imaging data including the corneal reflection light image L2 made incident on the sensor section 51; a bright spot position operation section 6 that calculates a position of the corneal reflection light image L2 in the imaging data; and a tremor signal operation section 7 that generates a third data string indicating a tremor component included in movement of the cornea 101 by calculating a difference between a first data string concerning temporal changes in position of the corneal reflection light image L2 and a second data string obtained by smoothing the first data string. Accordingly, an eye movement measurement apparatus capable of accurately detecting a tremor component is realized.