Aspiration Smoke Detector Optics for Focused Scattered-Light Sensing
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Solution Overview
Problem
Aspiration smoke detector (ASD) systems require high sensitivity to detect low concentrations of smoke particles but are limited by the type of detecting technology that can be used, affecting their reliability and cost.
Innovation Solution
A smoke detector for ASD systems uses a reflector to focus scattered light to a single focal point, enhancing sensitivity and accuracy by collecting more light at the photodetector, and employs a multi-wavelength light source to discriminate between different types of particles, reducing the need for additional optics and lowering manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high sensitivity is used to detect low concentrations of smoke particles, then detection capability is improved, but the type of detecting technology is limited and cost increases
Solution Approach 1:
The patent employs a curved reflector surface (spherical or parabolic) to focus scattered light from smoke particles onto the photodetector. This curvature enables efficient collection of scattered light across a wide angular range, significantly enhancing the intensity of light reaching the detector and thereby improving detection sensitivity without requiring additional expensive optical components.
Solution Approach 2:
The patent utilizes multi-wavelength light sources (e.g., UV, visible, and infrared wavelengths) to detect smoke particles. By detecting light scattering at multiple wavelengths simultaneously, the system can distinguish smoke particles from other particulates based on their wavelength-dependent scattering characteristics, thereby improving both sensitivity and particle discrimination capability.
2Measurement precision
If high sensitivity is used to detect low concentrations of smoke particles, then detection capability is improved, but reliability is affected
Solution Approach 1:
The patent employs multi-wavelength light detection to exploit the wavelength-dependent scattering properties of smoke particles. By measuring light scattering at multiple wavelengths (e.g., UV at 365nm, visible at 532nm, and infrared at 1064nm), the system can distinguish smoke particles from nuisance particles such as dust or cooking aerosols, thereby improving alarm accuracy and reliability while maintaining high sensitivity.
Solution Approach 2:
The patent uses the reflected and focused light signal from smoke particles to provide feedback to the control system. The photodetector converts the focused light intensity into an electrical signal that is processed by the control system to determine the presence and concentration of smoke, enabling real-time monitoring and reliable alarm generation based on predefined thresholds.
3Measurement precision
If additional focussing optics are used to redirect scattered light to the photodetector, then sensitivity is increased, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent employs a curved reflector surface (spherical or parabolic) to focus scattered light from smoke particles onto the photodetector. This curvature enables efficient collection of scattered light across a wide angular range, significantly enhancing the intensity of light reaching the detector and thereby improving detection sensitivity without requiring additional expensive optical components.
Solution Approach 2:
The reflector in the patent serves multiple functions: it collects scattered light from smoke particles, focuses the light onto the photodetector, and defines the detection chamber geometry. This multi-functionality eliminates the need for separate focusing lenses or additional optical components, reducing device complexity and manufacturing cost while maintaining high light collection efficiency.
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 increases sensitivity and accuracy while allowing the use of lower intensity light sources, reduces background noise, and discriminates between smoke and nuisance particles, improving the reliability and cost-effectiveness of ASD systems.
Implementation Method 1
a reflector, the reflector being configured to reflect light received at the reflector to a single focal point
Implementation Method 2
the reflector being configured to reflect light received at the reflector to a single focal point
Implementation Method 3
for detecting light scattered from the beam of light
Implementation Method 4
The light source is configured to emit a beam of light comprising a first wavelength, and emit a beam of light comprising a second wavelength
Data Source
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AI summary
A smoke detector (100) for use with an aspiration smoke detector (ASD) is described. The smoke detector comprises a light source (104) configured to emit a beam of light (108); a reflector (102) comprising an aperture (110), wherein the aperture is aligned with a direction of propagation of the beam of light when no scattering occurs; and a photodetector (106); wherein the reflector is configured to reflect light scattered from the beam of light received at the reflector to a single focal point; and wherein the photodetector is located at the single focal point. An aspiration smoke detector (ASD) system (2) comprising the smoke detector and a method of detecting smoke using the smoke detector are also described.