Smoke Detector Light Blocking Member Reducing False Alarms
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Solution Overview
Problem
Conventional smoke detectors experience a high false alarm rate due to environmental changes, such as temperature variations, which affect the detected reference light intensity and lead to unnecessary alarms.
Innovation Solution
The proposed solution involves an optical machine for smoke detectors that includes a substrate, a light sensor, a first light source, and a light blocking member. The light blocking member reduces the detected reference light intensity by blocking a part of the emission angle of the light source, thereby increasing the ratio of light intensity variation caused by smoke and reducing false alarms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the light source emission angle is reduced to decrease detected reference light intensity, then false alarm rate is reduced, but detection sensitivity may be compromised
Solution Approach 1:
The light blocking member creates a non-uniform light distribution by selectively blocking specific angular portions of the light source emission. This local modification of light intensity distribution allows the system to reduce overall detected reference light intensity (decreasing false alarms) while preserving sufficient light intensity in critical detection zones (maintaining detection sensitivity).
Solution Approach 2:
The light blocking member acts as an intermediary element between the light source and the detection space. It modulates the light intensity and angular distribution, serving as a control mechanism that balances the conflicting requirements of reducing false alarms through intensity reduction while maintaining detection sensitivity through selective angular preservation.
2Reliability
If a light blocking member is added to control light intensity, then false alarm rate is reduced, but device complexity increases
Solution Approach 1:
The light blocking function is extracted as a separate, dedicated component (light blocking member) with a specific geometric structure. This extraction allows the complexity to be localized to a single element rather than requiring complex control systems or multiple active components, simplifying the overall system architecture while achieving the desired light intensity control.
Solution Approach 2:
The light blocking member controls light intensity by modifying geometric parameters (opening angle, position, shape) rather than requiring active control mechanisms. This passive geometric approach reduces device complexity by eliminating the need for additional sensors, actuators, or control circuits that would be required for active intensity regulation.
3Measurement precision
If the light blocking member blocks part of the emission angle, then detected reference light intensity is reduced, but the ratio of light intensity variation due to smoke is increased
Solution Approach 1:
The light blocking member performs a preliminary action by blocking unwanted light angles before the light enters the detection space. This pre-filtering of light angles prevents excessive reference light intensity from reaching the sensor, thereby preliminarily establishing optimal detection conditions and preventing false alarms before they occur.
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 configuration enhances the detection sensitivity of the smoke detector by increasing the ratio of light intensity variation due to smoke, while also reducing the overall size of the smoke detector and minimizing false alarms caused by environmental changes.
Implementation Method 1
The light blocking member includes a first opening upon the first light source, and the first opening exposes a part of the first emission angle of the first light source close to the light sensor
Implementation Method 2
the optical smoke detector is set to give an alarm when detected brightness exceeds an alarm level
Implementation Method 3
The first light source is arranged on the substrate and having a first emission angle
Data Source
AI summary
There is provided an optical machine of a smoke detector including a substrate, a light source, a light sensor and a light blocking member. The light source and the light sensor are arranged on the substrate in a first direction. The light blocking member is arranged upon the light source and blocks a part of an emission angle of the light source in the first direction far away from the light sensor.