Chamber-less Smoke Sensor Using Multi-Wavelength Light
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Solution Overview
Problem
Commercial smoke sensors with chambers are prone to false alarms due to unwanted airborne particles, which can go undetected if they are small, and struggle to distinguish between smoke and other particles or scenarios, while eliminating the chamber exposes the sensor to ambient light, preventing detection.
Innovation Solution
A chamber-less smoke sensor design using multiple wavelengths of light and electronic filters to differentiate between ambient light and smoke signals, with algorithms to process scattered and obscured light, and polarizers to adjust for detector sensitivity and orientation, allowing for accurate smoke detection without chamber clogging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a chamber is used to contain the sensing element, then false alarms are reduced by preventing entry of unwanted particles, but small smoke particles (less than 0.5 microns) may go undetected and large particles cannot be distinguished from other airborne particles like steam or dust
Solution Approach 1:
The patent employs multiple wavelengths of light (different parameters) to detect particles of various sizes. By changing the wavelength parameter, the sensor can detect both small particles (0.5 microns and larger) and distinguish large particles from other airborne contaminants, resolving the limitation of single-wavelength detection in chambers.
Solution Approach 2:
The invention adds the dimension of wavelength variation to particle detection. Instead of relying solely on spatial filtering through chamber inlets, the patent introduces spectral dimension (multiple wavelengths) to enhance particle characterization and detection capability across different particle sizes.
2Productivity
If the chamber is eliminated to increase exposure of the sensing element to smoke, then detection efficiency is improved, but the sensing element is exposed to high intensity ambient light that floods the sensor and prevents smoke detection
Solution Approach 1:
The patent uses multiple wavelengths of light to differentiate between ambient light and smoke signals. By analyzing the spectral characteristics of scattered light at different wavelengths, the sensor can distinguish smoke particles from ambient light sources, enabling chamber-less operation while maintaining detection accuracy.
Solution Approach 2:
The patent introduces electronic filters and processing algorithms as intermediaries between the sensing element and the detection system. These intermediaries process the raw light signals to separate smoke-related scattered light from ambient light flooding, allowing the sensing element to be exposed to the environment without being overwhelmed by ambient light.
3Reliability
If controlled dimension inlets are used in the chamber, then unwanted particles are prevented from entering, but particles still accumulate at the inlets making it more difficult for smoke particles to diffuse into the chamber over time
Solution Approach 1:
The patent extracts the harmful function of the chamber (particle accumulation blocking inlets) while retaining the useful function (particle detection). By eliminating the chamber and using electronic filtering with multiple wavelengths, the system prevents particle accumulation issues while maintaining false alarm reduction through signal processing rather than physical barriers.
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 effectively reduces false alarms and improves the sensor's ability to detect smoke particles of various sizes, distinguishing them from other airborne particles and ambient light, enhancing selectivity and reducing nuisance alarms.
Implementation Method 1
Smoke sensors, such as commercial smoke sensors, often located inside of a housing or enclosure, use near infrared light scattering inside a small plastic chamber
Implementation Method 2
a first polarizer is coupled to the source, wherein the first polarizer is configured to obtain a reference electrical field orientation for at least one field associated with the light emitted by the source. A second polarizer is coupled to the at least one detector, wherein the second polarizer and the at least one detector are configured to detect a change in a distribution of orientations of the at least one electrical field relative to the reference orientation
Data Source
AI summary
A method for detecting smoke via a chamber-less smoke sensor includes applying one or more filters to eliminate a flooding of ambient light upon the smoke sensor and emitting, by a source, light. At least one detector detects at least a portion of the emitted light and a processor processes the detected light to signal an alarm condition when one or more threshold levels are reached. A chamber-less smoke sensor includes a light source configured to emit light and at least one detector configured to detect at least a portion of the emitted light. An electronic filter and/or a processor is configured to apply one or more filters to eliminate a flooding of ambient light upon the smoke sensor and process the detected light to signal an alarm condition when a threshold level is reached.