Optical Smoke Detector Using Multi-Wavelength Scattering Analysis
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Solution Overview
Problem
Existing scattered light smoke detectors struggle to accurately differentiate between smoke and other aerosols, often leading to false alarms due to their simplicity and reduced sensitivity, which can be exacerbated by the use of small measurement volumes or single scattering angles and wavelengths.
Innovation Solution
A method utilizing an optical scattered light detector with a single transmitter and receiver that records a series of scattered light values, sorts them by size, and assigns specific ranges to smoke and dust, allowing for improved differentiation through statistical analysis and signal processing, including the use of windows and normal levels to refine the detection of smoke and dust signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If additional sensors such as temperature and gas sensors are used to distinguish smoke from other aerosols, then the accuracy of smoke detection is improved, but the device complexity and cost increase
Solution Approach 1:
The patent changes the parameters of the light emitter by using multiple wavelengths (e.g., 450nm, 532nm, 650nm) and the parameters of the light receiver by measuring at multiple scattering angles. This allows the system to distinguish smoke from other aerosols based on their different scattering characteristics across wavelengths and angles, eliminating the need for additional temperature and gas sensors while maintaining high detection accuracy
Solution Approach 2:
The patent adds dimensional complexity to the measurement by incorporating multiple wavelengths and multiple scattering angles. Instead of using a single wavelength and single angle measurement, the system measures scattered light intensity across a spectrum of wavelengths and angles, creating a multi-dimensional signal space that enables differentiation of aerosol types without additional physical sensors
2Measurement precision
If multiple scattering angles and wavelengths are used to distinguish smoke from other aerosols, then the measurement precision is improved, but the device complexity increases
Solution Approach 1:
The patent employs a single light emitter that can operate at multiple wavelengths and a single light receiver that can detect scattered light at multiple angles. This multi-functional design allows one component to perform what would traditionally require multiple separate components, reducing device complexity while maintaining the ability to distinguish smoke from other aerosols through multi-parameter measurement
3Object-affected harmful factors
If a small measurement volume is used to reduce dust particle interference, then the false alarm rate from dust is reduced, but the sensitivity to smoke is significantly reduced
Solution Approach 1:
The patent compensates for the reduced sensitivity caused by small measurement volume by utilizing measurements at multiple scattering angles and wavelengths. The multi-parameter measurement approach extracts more information from each measurement, allowing the system to maintain high smoke sensitivity even with a small measurement volume that excludes large dust particles
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 enhances the accuracy of smoke detection while reducing the influence of dust and water vapor, enabling clearer distinction and potentially reducing false alarms, even with simple detector systems, and can be used in conjunction with additional sensors for enhanced performance.
Implementation Method 1
an optical scattered light detector with at least one light emitter (7), which emits light into a measurement volume (16), and with at least one light receiver (8) arranged at at least one angle to the radiation axis of the light emitter (7), with which scattered light from smoke or dust particles (12) inside of the measurement volume (16) is received
Data Source
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AI summary
Disclosed is a hazard detector and a method for detecting smoke, the detector comprising an optical scattered light detector which has at least one light emitter and at least one light receiver located at an angle to the emission axis of the light emitter. The light receiver receives light scattered by smoke and/or dust within the measuring volume. Statistical effects are used to achieve a more target-oriented identification of smoke by the sorting of measured values according to their size.