Fire Sensing Device With Backup LED Self-Testing
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Solution Overview
Problem
Fire sensing devices in large facilities often degrade due to contamination and operational issues, leading to inaccurate fire detection and the need for costly and labor-intensive recalibration or replacement, which can create environmental waste.
Innovation Solution
Incorporating a backup transmitter LED in fire sensing devices to replace or supplement the primary LED when degraded, reducing duty cycles to extend the operational life of both LEDs and allowing for self-testing and calibration without physical removal, thereby extending the service life and reducing waste.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensitivity testing is performed at the facility, then accurate detection of fire sensing device performance is achieved, but physical access difficulty and deployment of specialist equipment make the testing impractical
Solution Approach 1:
The fire sensing device performs self-diagnostics by internally monitoring the LED light output and comparing it against stored baseline values. The processor automatically detects LED degradation without requiring external testing equipment or specialist intervention, allowing the device to self-verify its operational status.
Solution Approach 2:
A photodiode serves as an intermediary sensor within the fire sensing device that directly measures the LED light output. This internal photodiode acts as a mediator between the LED and the processor, enabling automatic monitoring of LED performance without requiring external testing equipment.
2Reliability
If smoke detectors are replaced after a particular time period, then devices that may still be performing accurately are discarded, but this approach is costly and labor intensive
Solution Approach 1:
The system performs preliminary monitoring of LED performance by continuously tracking light output and comparing it against baseline values stored in memory. This early detection of degradation trends allows for proactive replacement planning based on actual device condition rather than arbitrary time schedules.
Solution Approach 2:
The system monitors changes in LED light output parameters over time and compares them against predetermined thresholds. When the light output falls below the threshold indicating degradation, the system triggers a replacement indication, allowing extension of device service life based on actual performance rather than fixed time intervals.
3Duration of action of moving object
If transmitter LED duty cycles are reduced, then operational life of the LED is extended, but fire detection sensitivity may be compromised
Solution Approach 1:
The system dynamically adjusts the monitoring strategy based on LED performance data. As the LED ages and light output decreases, the system adapts by becoming more sensitive to changes in the already-reduced light output, maintaining detection capability throughout the extended LED lifecycle.
Solution Approach 2:
The photodiode provides continuous feedback on LED light output levels to the processor. This feedback mechanism allows the system to detect even small changes in the reduced light output from duty-cycled LEDs, ensuring that fire detection sensitivity is maintained despite the lower overall light emission.
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
This approach reduces the frequency of labor-intensive recalibrations and replacements, leading to cost savings, labor savings, and a lower environmental impact by maintaining accurate fire detection capabilities over a longer period.
Implementation Method 1
a photodiode configured to detect the first light and the second light
Data Source
AI summary
A fire sensing device is described herein. One fire sensing device includes a first transmitter light-emitting diode (LED) configured to emit a first light, a second transmitter LED configured to emit a second light, a controller configured to command the first transmitter LED to cease emitting the first light and the second transmitter LED to start emitting the second light, and a photodiode configured to detect the first light and the second light.