Motion Detector Anti-Masking System Using Segmented Optical Detection
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Solution Overview
Problem
Intruders can defeat existing anti-masking systems in motion detectors by using techniques such as coating lenses with opaque substances or blocking the detectors, which reduces the effectiveness of tampering detection.
Innovation Solution
An anti-masking system that employs a combination of energy sources, spreading lenses, reflectors, and retroreflectors, along with a controller to sequentially or simultaneously supply energy and monitor signals from sensors to detect objects and issue an alarm only when a predetermined trigger time is exceeded, thereby reducing the likelihood of system defeat.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single anti-masking function is used in motion detectors, then the system can detect tampering attempts, but intruders can defeat the system by developing countermeasures targeting that specific function
Solution Approach 1:
The patent divides the anti-masking function into multiple independent anti-masking functions (e.g., lens masking detection, reflector masking detection, retroreflector masking detection). Each function operates independently with its own sensor and detection mechanism, so that defeating one function does not compromise the entire anti-masking system.
Solution Approach 2:
The controller dynamically selects and executes different anti-masking functions at different times rather than using a single static anti-masking function. This temporal variation in detection approaches makes it difficult for intruders to develop countermeasures that work against all detection methods simultaneously.
2Reliability
If multiple anti-masking functions are executed at different times, then the likelihood of system defeat is reduced, but the system complexity increases
Solution Approach 1:
A single controller is designed to perform multiple functions: it manages the energy source, controls the timing of different anti-masking functions, processes signals from multiple sensors, and coordinates the overall detection sequence. This multi-functional controller reduces the need for separate control circuits for each anti-masking function.
Solution Approach 2:
The patent combines multiple anti-masking detection mechanisms into a single integrated system housed in one motion detector unit. The energy source, multiple sensors (lens sensor, reflector sensor, retroreflector sensor), and controller are merged into a unified structure that operates as a single device, reducing installation complexity and space requirements.
3Reliability
If continuous energy supply is used for anti-masking detection, then detection coverage is maintained, but energy consumption increases
Solution Approach 1:
Instead of continuous energy supply, the controller activates the energy source periodically to execute different anti-masking functions at different times. The energy source is turned on only when needed for specific detection sequences, and off during other periods, significantly reducing overall energy consumption while maintaining detection availability.
Solution Approach 2:
The controller pre-plans and sequences the execution of different anti-masking functions, activating the energy source only when a specific detection function is needed. This preliminary planning allows the system to maintain detection coverage across different time periods without requiring continuous energy supply.
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 system effectively detects tampering attempts by varying the energy supply sequence and sensor monitoring, reducing false alarms and enhancing the resilience against intruder countermeasures, ensuring reliable motion detection in security systems.
Implementation Method 1
a lens sensor to detect energy emitted from the spreading lens that is reflected back into the housing through the lens from an object
Implementation Method 2
a retroreflector configured to receive and reflect energy from an energy source. A retroreflector sensor detects energy reflected back into the housing by the retroreflector
Implementation Method 3
at least one reflector located outside the housing adjacent the lens. The at least one reflector is configured to reflect energy received from an energy source back into the housing through the lens
Data Source
AI summary
An anti-masking system and method for a motion detector includes a plurality of anti-masking components such as a spreading lens, at least one reflector located outside a housing of the motion detector, and a retroreflector located on the housing proximate to a lens. The system and method uses the plurality of anti-masking components to determine whether the lens of the motion detector has been masked by an object.