Optical Smoke Detection Unit With Self-Monitoring LED Pair
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing optical smoke detection units face reliability issues due to aging light-emitting diodes and contamination, which affect the accuracy and longevity of smoke detection, requiring external monitoring and compensation for reduced light output and sensitivity.
Innovation Solution
The optical smoke detection unit optically couples two light-emitting diodes, allowing one to function as a photodiode to monitor the other's luminous flux, and uses a control unit to adjust the light output based on detected photocurrent, eliminating the need for external photosensors and preventing dirt interference in the optical path.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If external photosensors are used to monitor light output, then monitoring accuracy is improved, but device complexity increases
Solution Approach 1:
The patent combines the light-emitting function and light-detecting function into a single integrated unit. The LED module includes both the light-emitting LED and a photodiode detector within the same housing, eliminating the need for separate external photosensors. This merging reduces device complexity while maintaining monitoring capability through the photodiode's ability to detect light output changes.
Solution Approach 2:
The LED module serves multiple functions: it emits light for smoke detection and simultaneously monitors its own light output through the integrated photodiode. This multi-functionality eliminates the need for separate monitoring components, reducing overall device complexity while maintaining accurate light output monitoring for aging compensation.
2Measurement precision
If separate photosensors are used for monitoring, then detection accuracy is improved, but susceptibility to contamination increases
Solution Approach 1:
The photodiode detector is nested within the LED housing, positioned to receive light directly from the LED through an internal optical path. This nesting arrangement protects the detection path from external contamination while maintaining accurate light output monitoring. The detector is shielded from ambient light and external dirt particles that would affect separate external photosensors.
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 solution enhances the reliability and longevity of smoke detection by internally monitoring and compensating for aging and contamination, ensuring consistent luminous flux and maintaining detection accuracy over time without external interference.
Implementation Method 1
at least one of the light-emitting diodes illuminates the other light-emitting diode with part of the emitted light... record a photocurrent flowing through it as a measure of the luminous flux emitted by the controlled light-emitting diode
Data Source
AI summary
The invention relates to an optical smoke detection unit, particularly for a smoke detector. It comprises a first and second light-emitting diode (L1, L2), each for emitting single-, two-, or multi-colored light, a photoreceiver (2) for smoke detection, and a control unit (MC) connected to the light-emitting diodes and the photoreceiver for electrically controlling the light-emitting diodes and for evaluating a received signal output by the photoreceiver with respect to fire characteristics. According to the invention, the light-emitting diodes are optically coupled (OK) to each other such that at least one of the light-emitting diodes illuminates the other light-emitting diode with a portion of the emitted light.The control unit is configured to alternately activate one of the LEDs and switch the other LED to photodiode mode, simultaneously measuring the photocurrent (IL1, IL2) flowing through it as a measure of the emitted luminous flux of the activated LED. It is also configured to derive and output aging information for the LED, dependent on the degree of photocurrent decay, and/or to modify the electrical control of this LED to correct for a corresponding decrease in the emitted luminous flux.