LED Circuit Breaker for Iris Scanner Retinal Safety
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Solution Overview
Problem
The use of near-infrared LED light in iris scanners poses a risk of damaging the retina due to excessive intensity and duration of exposure, as there is no defensive reflex to protect the eyes from invisible infrared light.
Innovation Solution
A LED circuit breaker is introduced, comprising a controlled switch, a sensor, and a control circuit, which measures the power driving the LEDs and breaks the circuit if the exposure time exceeds a safe threshold, thereby preventing excessive infrared exposure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If near-infrared LED light is used for iris scanning, then image quality is improved, but retinal damage risk increases
Solution Approach 1:
The patent implements a feedback mechanism where a sensor continuously monitors the LED power output and the control circuit integrates this information over time. When the accumulated exposure value exceeds a predetermined threshold, the system automatically reduces or shuts off the LED power, creating a closed-loop control system that prevents retinal damage while maintaining scanning functionality.
Solution Approach 2:
The system dynamically changes the LED power parameter based on accumulated exposure. The control circuit adjusts the power delivery from the LED driver by monitoring sensor feedback and modifying the operating parameters in real-time, transitioning between different power levels to stay within safe exposure limits while achieving necessary image quality.
2Productivity
If LED power is increased to improve image quality, then scanning performance is improved, but exposure time must be limited to prevent damage
Solution Approach 1:
The sensor provides continuous feedback on actual LED power delivery, and the control circuit integrates this information over time. This feedback loop allows the system to automatically manage exposure duration by reducing power when the accumulated exposure approaches the safety threshold, ensuring both scanning performance and safety are maintained.
Solution Approach 2:
The system dynamically adjusts LED power delivery rather than using fixed parameters. The control circuit continuously modifies the power output based on real-time sensor feedback and accumulated exposure data, enabling flexible management of the trade-off between scanning performance and exposure time limits.
3Reliability
If a sensor and control circuit are added to monitor LED power, then safety is improved, but device complexity increases
Solution Approach 1:
The LED circuit breaker is designed to be self-regulating through an integrated sensor and control circuit that automatically monitor and adjust LED power without external intervention. The system serves its own safety needs by continuously self-monitoring exposure levels and automatically reducing power when thresholds are approached, eliminating the need for external safety mechanisms.
Solution Approach 2:
The control circuit acts as an intermediary between the LED driver and the LED source, mediating the power delivery. This intermediate component processes sensor feedback and translates it into appropriate power control signals, simplifying the overall safety implementation by centralizing the control logic in a dedicated circuit rather than requiring complex external monitoring systems.
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 LED circuit breaker effectively limits the emission of LED light to safe levels, preventing potential retinal damage from excessive infrared exposure during iris scanning operations.
Implementation Method 1
the current sensor being a Hall effect sensor
Data Source
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AI summary
The invention relates to a LED circuit breaker (23) intended to be mounted serially between a LED driver (21) and a LED source (22), the LED circuit breaker (23) comprising: - a controlled switch (231) serially mounted between the LED driver (21) and a LED source (22) for closing or opening the circuit, - a sensor (232) measuring the power provided by the LED driver (21) to the LED source (22), the sensor (232) providing a measure, - a control circuit (233) connected to the sensor (232) for receiving the measure and connected to the controlled switch (231) for controlling said switch, the control circuit (233) being configured for: ∘ making a time integration of the measure for obtaining an illumination value (CNT) representative of a quantity of illumination, ∘ opening the controlled switch (231) when the illumination value exceeds a predetermined threshold.