Multi-Wavelength Smoke Detector for False Alarm Reduction
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Solution Overview
Problem
Existing smoke detectors face issues with high false alarm rates, inability to distinguish between fire smoke and non-fire smoke based on particle size, and uniform response to both black and white smoke, due to reliance on smoke concentration alone.
Innovation Solution
A smoke detector design utilizing two transmitting tubes with different wavelengths of light sources and a control device to determine the presence of fire by analyzing the intensity and ratio of outputs from refracted and scattered light, reducing false alarms and improving sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single light source is used to detect smoke concentration, then the detection structure is simple, but the ability to distinguish between fire smoke and non-fire smoke is lost, leading to high false alarm rates
Solution Approach 1:
The single light source is segmented into multiple light sources with different wavelengths (e.g., infrared and visible light). Each wavelength interacts differently with smoke particles of varying sizes, enabling the system to distinguish between fire smoke (smaller particles) and non-fire smoke (larger particles) by analyzing the scattering patterns at each wavelength separately.
Solution Approach 2:
The detection system transitions from a single-dimensional measurement (smoke concentration only) to multi-dimensional measurement by incorporating multiple wavelengths. This adds the wavelength dimension to the detection space, allowing differentiation of smoke types based on their distinct scattering characteristics at different wavelengths while maintaining structural feasibility.
2Measurement precision
If detection is based solely on smoke concentration, then the detection method is simple, but the response to different smoke types (black and white smoke) is uniform, reducing detection accuracy
Solution Approach 1:
Different wavelengths of light are assigned to detect different aspects of smoke characteristics. For example, infrared light may be more sensitive to certain particle sizes while visible light detects others. By analyzing the local scattering response at each wavelength, the system achieves precise differentiation between smoke types with varying particle size distributions.
Solution Approach 2:
The detection method changes the physical parameter of light wavelength to probe different scattering mechanisms. By varying the wavelength parameter, the system can selectively detect smoke particles of different sizes, thereby achieving precise measurement of smoke type characteristics that cannot be obtained with a single wavelength.
3Measurement precision
If multiple wavelengths are used to distinguish smoke types, then the detection precision improves, but the device complexity and cost increase
Solution Approach 1:
Multiple light sources with different wavelengths are merged into a single integrated detection chamber and sharing a common light receiving device. This combining approach allows the system to achieve multi-wavelength detection capabilities while avoiding the complexity of multiple separate detection systems, thereby reducing overall device complexity and cost.
Solution Approach 2:
The light receiving device is designed to be universal, capable of detecting scattered light from multiple wavelengths simultaneously. This multi-functional receiver can process signals from different wavelength sources, eliminating the need for separate receivers for each wavelength and thereby reducing device complexity while maintaining high measurement precision.
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 solution enables more precise smoke detection and alarm triggering, reducing false alarms and providing a uniform response to various smoke types, including black and white smoke, by distinguishing between fire and non-fire smoke based on particle size analysis.
Implementation Method 1
a receiving tube, where the first ray of light and the second ray of light can be incident after refraction and/or scattering
Implementation Method 2
a receiving tube, where the first ray of light and the second ray of light can be incident after refraction and/or scattering
Implementation Method 3
the optical scattering intensity model of smoke particles is established under the Miller scattering principle so as to measure the total scattering (absorption and scattering) of smoke particles with regard to incident light of different wavelengths. The formula for calculating the Miller scattering parameter that determines the scattering intensity is q=4πdλ−1 sin(θ/2), where the scattering intensity is in direct proportion to the particle diameter d and in inverse proportion to the wavelength of the incident light
Data Source
AI summary
A smoke detector comprising a body, having a detection chamber therein; a first transmitting tube and a second transmitting tube, arranged in the body and configured to be capable of transmitting a first ray of light and a second ray of light into the detection chamber, respectively; a receiving tube, where the first ray of light and the second ray of light can be incident after refraction and/or scattering, and which generates outputs according to the intensity of incident light; and a control device, coupled with the receiving tube to receive a first output generated by the first ray of light on the receiving tube and a second output generated by the second ray of light on the receiving tube, and configured to determine whether there is a fire based on a difference or ratio between the first output and the second output, or the combination thereof.