Smoke Detector Light Source Illumination Deviation
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Solution Overview
Problem
Current smoke detectors experience high false alarm rates due to dust accumulation and varying smoke types, as well as environmental disturbances, leading to inadequate sensitivity and delayed alarm times.
Innovation Solution
A smoke detector design that includes a processor for distinguishing different types of smoke, adjusts condition thresholds based on detection results, and uses protrusion structures and multiple light sources to block reflected light from dust and distinguish between smoke and disturbances, while also moving the illumination region of the light source toward the sensor to enhance scattered light intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single alarm threshold is used for scattered light intensity, then the smoke detector can be manufactured simply, but it causes false alarms for some smoke types and delays alarm time for others
Solution Approach 1:
The patent implements dynamic threshold adjustment by using multiple predetermined condition thresholds corresponding to different smoke profiles. The system automatically selects and switches between different alarm thresholds based on the detected smoke type, transforming the static single-threshold system into a dynamic multi-threshold system that adapts to different fire conditions.
Solution Approach 2:
The patent changes the alarm threshold parameter based on smoke type detection. Different smoke profiles (e.g., smoldering vs. flaming) have different scattered light characteristics, and the system adjusts the alarm threshold parameter accordingly to optimize detection sensitivity for each smoke type while reducing false alarms.
2Device complexity
If the light sensor receives reflected light from dust accumulation, then the device structure remains simple, but false alarms are triggered
Solution Approach 1:
The patent extracts and removes the harmful reflected light from dust accumulation before it reaches the light sensor. By introducing a light blocking member that specifically blocks the path of reflected light while allowing scattered light from smoke to reach the sensor, the system eliminates the source of false alarms without fundamentally changing the optical detection principle.
Solution Approach 2:
The light blocking member acts as an intermediary element between the light source and the light sensor. It selectively intercepts reflected light from dust accumulation, preventing it from reaching the sensor, while maintaining the passage of scattered light from smoke particles, thus mediating between the need for simple structure and the requirement to avoid false alarms.
3Illumination intensity
If the illumination region is moved toward the light sensor, then scattered light intensity increases, but direct light may reach the sensor causing false readings
Solution Approach 1:
The ring-shaped light blocking member serves as an intermediary structure that allows the illumination region to be moved toward the light sensor for enhanced scattered light intensity, while simultaneously preventing direct light from reaching the sensor. The ring structure blocks direct light paths while permitting scattered light to reach the sensor, thus mediating between the need for high illumination intensity and accurate detection.
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 design significantly reduces false alarm rates by accurately differentiating between smoke and environmental disturbances, improving sensitivity, and dynamically adjusting thresholds for timely alarm activation.
Implementation Method 1
The light sensor receives reflected or scattered light of the light source only when there is smoke entering the smoke detector
Implementation Method 2
an inner surface of the smoke detector is coated with light absorption material to avoid inner reflection without smoke therein
Data Source
AI summary
There is provided a smoke detector including a substrate, a light source and a light sensor. The light source and the light sensor are arranged adjacently on the substrate. The substrate is arranged with an asymmetric structure to cause an illumination region of the light source to deviate toward the light sensor thereby increasing a ratio of light intensity reflected by smoke with respect to reference light intensity.