Smoke Detector With Dual Scattering Angles
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Solution Overview
Problem
Conventional photoelectric smoke detecting devices are prone to false alarms from cooking smoke due to high sensitivity and delayed alarms from smoke generated by burning foam materials, as they rely on a single light-receiver for detection.
Innovation Solution
A smoke detecting device with a main body containing a smoke detecting chamber, a light-emitter, a first light-receiver, and a second light-receiver, where the optical axes of the light-receivers define different scattering angles, allowing the device to differentiate between smoke types and reduce false alarms or delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single light-receiver is used for detection, then the device structure is simple, but the device is prone to false alarms from cooking smoke
Solution Approach 1:
The patent divides the detection function into multiple independent light-receivers (first light-receiver and second light-receiver) positioned at different scattering angles. Each light-receiver independently detects smoke particles, and the control unit analyzes the signals from both receivers to distinguish between cooking smoke and fire smoke, thereby reducing false alarms while maintaining reasonable structural complexity.
Solution Approach 2:
The patent assigns different detection characteristics to different light-receivers by positioning them at different scattering angles relative to the light-emitter. The first light-receiver is positioned at a first scattering angle and the second light-receiver at a second scattering angle, creating localized detection zones with different sensitivities to various smoke types, enabling differentiated response to cooking smoke versus fire smoke.
2Reliability
If the sensitivity is reduced to avoid false alarms, then the false alarm rate decreases, but the alarm signal for smoke from burning foam materials is delayed
Solution Approach 1:
The patent segments the detection sensitivity into different channels by using multiple light-receivers at different scattering angles. The control unit can selectively respond to signals from different light-receivers based on the type of smoke detected, maintaining high sensitivity for fire smoke (including foam material burning) while filtering out cooking smoke false alarms through pattern recognition from multiple sensors.
Solution Approach 2:
The patent changes the detection parameters by positioning light-receivers at different scattering angles, which alters the light path and detection characteristics. This creates different detection parameters for different smoke types, allowing the system to optimize sensitivity for fire smoke detection while reducing responsiveness to cooking smoke, thus avoiding both false alarms and delays.
3Device complexity
If the optical axis of the first light-receiver is collinear with the light-emitter, then the detection path is simple, but the device cannot differentiate between smoke types
Solution Approach 1:
The patent introduces asymmetry in the optical arrangement by positioning the first light-receiver and second light-receiver at different scattering angles relative to the light-emitter. The first light-receiver is at a first scattering angle and the second light-receiver at a second scattering angle, creating an asymmetric detection geometry that enables the system to distinguish between different smoke types based on their scattering characteristics.
Solution Approach 2:
The patent adds a dimensional aspect to the detection system by introducing multiple scattering angles in the optical arrangement. Instead of a single collinear detection path, the system uses angular separation to create multiple detection dimensions, allowing differentiation between smoke types based on their light scattering properties at different angles.
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 device provides more accurate fire detection by reacting differently to smoke particles from various sources, thereby avoiding false alarms and ensuring timely alerts.
Implementation Method 1
when there is no smoke, the signal intensity of light received by the light-receiver is the weakest. However, if smoke particles enter the inside of the photoelectric detecting device, the originally-direct light will become a scattered light due to the collision with the smoke particles
Implementation Method 2
the photoelectric detecting device includes a light-emitter and a light-receiver
Data Source
AI summary
A smoke detecting device includes a main body, a light-emitter, a first light-receiver, and a second light-receiver. The main body includes a smoke detecting chamber formed therein. The light-emitter is located within the smoke detecting chamber. The first light-receiver is located within the smoke detecting chamber. An optical axis of the first light-receiver and an optical axis of the light-emitter cooperatively define a first scattering angle there-between. The second light-receiver is located within the smoke detecting chamber. An optical axis of the second light-receiver and an optical axis of the light-emitter corporately define a second scattering angle there-between. The second light-receiver is closer to the light-emitter than to the first light-receiver. The second scattering angle is smaller than the first scattering angle.