Fire Detector Noise Assessment via Periodic Light Emission
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Solution Overview
Problem
Conventional fire detectors face misjudgment issues due to noise interference in smoke detection signals, as existing noise assessment methods fail to accurately distinguish between noise and smoke-related signal changes, leading to errors in fire determination.
Innovation Solution
The fire detector employs a multi-mode noise assessment system that evaluates zero-point and smoke light reception signals through repeated light emission and reception cycles, using various threshold and averaging techniques to identify and remove noise, ensuring accurate smoke detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If noise assessment is performed using zero-point light reception signal only, then the assessment process is simple, but noise mixed in smoke light reception signal cannot be detected
Solution Approach 1:
The patent segments the light reception signal into two distinct components: zero-point light reception signal (when light emission stops) and smoke light reception signal (when light emission occurs). By separating these signals and assessing noise in both, the system achieves comprehensive noise detection without excessive complexity. The control unit independently processes each signal type through specific assessment modes.
Solution Approach 2:
The control unit is designed with multi-functionality to handle different noise assessment scenarios. It implements multiple assessment modes (first through fifth modes) that can evaluate both zero-point and smoke light reception signals. This universal approach allows the same control unit to detect various types of noise interference regardless of when they occur in the light emission cycle.
2Reliability
If smoke light reception signal is used for noise assessment, then all light reception signals are covered, but it becomes impossible to distinguish between smoke-induced signal changes and noise
Solution Approach 1:
The light emitting unit operates periodically with distinct phases: light emission periods and light emission stop periods. This periodic action creates temporally separated signal components that can be independently assessed. By evaluating noise during both the emission phase (smoke light reception signal) and non-emission phase (zero-point light reception signal), the system distinguishes noise from smoke-induced changes through temporal pattern recognition.
Solution Approach 2:
The control unit dynamically adapts its assessment strategy based on the current operational phase. During light emission stop periods, it applies assessment modes focused on zero-point signal characteristics. During light emission periods, it switches to assessment modes suitable for smoke light reception signals. This dynamic adjustment allows precise noise detection while maintaining the ability to distinguish smoke-related variations.
3Measurement precision
If light emission stops completely for noise assessment, then zero-point signal can be obtained, but smoke detection opportunity is lost
Solution Approach 1:
Instead of complete light emission cessation, the system employs periodic light emission with brief stop intervals. During these short stop periods, zero-point light reception signals are obtained for noise assessment. Immediately after, light emission resumes to detect smoke light reception signals. This periodic cycle ensures both noise assessment and smoke detection occur frequently without significant loss of detection opportunities.
Solution Approach 2:
The system performs preliminary noise assessment during light emission stop periods before proceeding to smoke detection during light emission periods. By completing the noise assessment phase first, the system prepares accurate baseline data that enhances subsequent smoke detection accuracy, ensuring both functions are fulfilled efficiently in sequence.
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 approach effectively assesses and removes noise from smoke detection signals, preventing misjudgments and ensuring reliable fire detection by inhibiting noise interference, including instantaneous and long-term noise, thereby stabilizing fire judgment processes.
Implementation Method 1
a light-receiving portion that receives the light emitted from the light-emitting portion and outputs a light reception signal
Data Source
Figure 1
Figure 2
Figure 3(A)~3(C)
AI summary
This fire detector is provided with a light-emitting portion that repeats stopping of light emission and light emission a plurality of number of times in predetermined light emission periods during a predetermined smoke detection operation time set for each first period; a light-receiving portion that receives the light emitted from the light-emitting portion and outputs a light reception signal during the smoke detection operation time; a light reception signal detecting portion that detects as a zero-point light reception signal the light reception signal that the light-receiving portion outputs at each light emission stop timing of the smoke detection operation time, and detects as a smoke light reception signal the light reception signal that the light-receiving portion outputs at each light emission timing; a smoke detecting portion that detects a smoke detection signal based on the zero-point light reception signals of a plurality of number of times and the smoke light reception signals of a plurality of number of times detected by the light reception signal detecting portion; and a noise assessing-processing portion that assesses the presence of mixing-in of noise to the light reception signal based on the zero-point light reception signals of a plurality of number of times and the smoke light reception signals of a plurality of number of times, and carries out noise removal processing in a case of having assessed that the noise is mixed in.