Ophthalmic Probe Detection Using Back-EMF Decay
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Solution Overview
Problem
Existing rebound tonometers consume significant energy for probe detection and fail to accurately determine if a probe is present or stuck, leading to inefficiencies in the measurement process.
Innovation Solution
A low-energy detection method using a temporary current pulse to induce a counter-electromotive force voltage spike, analyzing its decay behavior to determine probe presence or absence, and detecting potential jams without interfering with normal measurement operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the front coil is briefly energized to move the probe for detection, then probe presence can be detected, but significant energy is consumed
Solution Approach 1:
The system performs a preliminary check by monitoring the back EMF signal that naturally occurs when the rear coil is energized to hold the probe, before actually launching the probe for measurement. This preliminary detection action allows the system to verify probe presence without consuming the energy required for a full probe launch and recovery cycle.
Solution Approach 2:
The invention extracts the detection function from the main measurement launch sequence. Instead of using the full probe launch mechanism for detection, it separates the detection capability by monitoring the back EMF signal during the normal probe holding phase, thereby eliminating the need for additional energy-consuming detection maneuvers.
2Measurement precision
If the front coil is energized to detect probe motion, then probe presence is indicated, but stuck or jammed probes are incorrectly identified as absent
Solution Approach 1:
The system uses feedback from the back EMF signal characteristics to determine probe status. By monitoring the magnitude and temporal profile of the back EMF signal when the rear coil is energized, the system can distinguish between a properly positioned probe (which generates a specific back EMF signature) and an absent or stuck probe (which generates a different signature), thereby improving detection reliability.
Solution Approach 2:
The invention replaces the mechanical probe launch-and-recover detection method with an electromagnetic field-based detection method. Instead of physically moving the probe to detect its presence, the system uses electromagnetic induction to sense the probe's magnetic signature through back EMF monitoring, providing more reliable detection without mechanical intervention.
3Use of energy by moving object
If a simple presence detection method is used, then energy consumption is reduced, but the ability to detect stuck or jammed probes is lost
Solution Approach 1:
The system monitors changes in the back EMF signal parameters (magnitude, duration, waveform characteristics) to detect probe status. By analyzing these parameter variations, the system can identify stuck or jammed probes using minimal energy, as the detection is performed passively during the normal probe holding phase rather than requiring active probe manipulation.
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 method efficiently detects probe presence and jams with minimal energy consumption, ensuring accurate and reliable operation of the tonometer without disrupting the measurement cycle.
Implementation Method 1
detecting a counter-electromotive force (i.e., 'back EMF') voltage spike induced in the electromagnetic coil by the current pulse
Data Source
AI summary
A method of detecting presence or absence of a magnetic measurement probe at a measurement launch position in an electromagnetic coil of an ophthalmic instrument includes applying a temporary current pulse to the electromagnetic coil, detecting a counter-electromotive force voltage spike induced in the electromagnetic coil by the current pulse, evaluating a decay behavior of the counter-electromotive force voltage spike, and correlating the decay behavior of the counter-electromotive force voltage spike to presence or absence of the measurement probe at the measurement launch position.