Video Camera Smoke Detection Using Patterned Target Contrast
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Solution Overview
Problem
Conventional smoke detectors are impractical for large areas with high ceilings due to installation difficulties and high costs, as they require precise alignment and have limited sensitivity, necessitating the use of numerous detectors.
Innovation Solution
A system utilizing a patterned target and a video camera with a processor to detect smoke by analyzing spatial frequency changes in images, which simplifies installation, reduces maintenance, and provides cost-effective smoke detection by using a camera to capture images of a patterned target, optionally with NIR illumination, and processing the images to determine smoke presence.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If projected and reflected beam smoke detectors are used, then smoke detection capability is provided, but installation cost and complexity increase due to precise alignment requirements
Solution Approach 1:
The patent replaces the mechanical alignment system of beam detectors with an optical imaging system. Instead of requiring precise alignment between emitter and receiver, the system uses a camera to capture images of a patterned target through the atmosphere, substituting mechanical precision requirements with optical detection that is inherently more tolerant of misalignment.
Solution Approach 2:
The patent introduces a patterned target as an intermediary element between the light source and detector. This target serves as a reference object that allows the system to measure atmospheric attenuation without requiring direct alignment between transmitter and receiver, thereby eliminating the precise alignment requirement while maintaining detection capability.
2Area of stationary object
If multiple point sensors are deployed to cover large areas, then smoke detection coverage is improved, but installation difficulty and cost increase
Solution Approach 1:
The patent transitions from point-based detection (0D) to area-based imaging detection (2D). By using a camera to capture images of an extended patterned target, the system achieves coverage of a large area with a single detector, eliminating the need to deploy multiple point sensors throughout the space.
3Length of stationary object
If beam-based detectors are used, then detection range is extended, but sensitivity is limited and maintenance cost increases
Solution Approach 1:
The patent performs preliminary calibration by capturing images of the patterned target under known conditions to establish baseline contrast values. This preliminary action allows the system to later detect smoke by comparing current images against the calibrated reference, thereby improving sensitivity through differential measurement rather than absolute threshold 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 solution enables effective smoke detection with minimal false alarms and diverse installation configurations, as it measures contrast or modulation depth changes independent of intensity or color variations, allowing for precise detection of smoke presence and density without the need for precise alignment.
Implementation Method 1
a camera to capture images of a patterned target
Implementation Method 2
processing the images to determine smoke presence by analyzing spatial frequency changes in images
Data Source
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AI summary
A smoke detector includes processing circuitry coupled to a camera. The field of view of the camera contains one or more targets, each having spatial indicia thereon. The processing circuitry collects a sequence of spatial frequency measures, such as contrast indicating parameters. Members of the sequence can be compared to at least one reference spatial frequency measure to establish the presence of smoke between the target and the camera.