Pyroelectric Sensor Pairs for Directional Motion Detection
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Solution Overview
Problem
Existing motion detection systems using pyro-electric sensors face challenges in accurately differentiating between moving objects and stationary thermal effects, leading to false alarms and inefficient detection of directional motion.
Innovation Solution
A motion detection system employing two pairs of pyro-electric elements with independent local temperature compensation, where only one element from each pair views the motion detection field, and a signal processor that provides output indications based on temperature differences and directional motion, effectively distinguishing between moving objects and thermal effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If pyro-electric sensors are used for motion detection, then thermal effects can be detected, but false alarms occur due to inability to differentiate between moving objects and stationary thermal effects
Solution Approach 1:
The sensor array is divided into multiple pyro-electric elements arranged in pairs, where each pair independently processes thermal signals. This segmentation allows the system to compare signals from adjacent elements and differentiate between stationary thermal effects (affecting both elements equally) and moving objects (affecting one element more than the other), thereby reducing false alarms while maintaining detection accuracy.
Solution Approach 2:
Each pyro-electric element pair performs local temperature compensation independently, comparing thermal signals only between its paired neighbor. This local processing approach enables the system to compensate for stationary thermal effects at each local position while maintaining sensitivity to moving objects, resolving the contradiction between reliable thermal detection and false alarm reduction.
2Measurement precision
If multiple pyro-electric elements are used to improve detection accuracy, then directional motion can be detected, but device complexity increases
Solution Approach 1:
The pyro-electric elements are arranged in an asymmetric configuration where only specific elements in each pair view the motion detection field through the window, while their paired neighbors provide local temperature compensation without direct field viewing. This asymmetric arrangement enables directional motion detection through differential signal processing while keeping the physical structure relatively simple and manageable.
Solution Approach 2:
Each pyro-electric element serves multiple functions: elements viewing the field detect both thermal presence and directional motion, while their paired neighbors provide local temperature compensation. This multi-functionality allows the system to achieve directional detection capability without proportionally increasing overall device complexity, as each element contributes to multiple detection objectives.
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 reduces false alarms by accurately detecting directional motion and differentiating between moving objects and stationary thermal effects, enhancing the reliability of motion detection.
Implementation Method 1
a motion detector system including at least first and second pairs of pyro-electric elements
Implementation Method 2
providing an output indication of crossing the field of view by an object having a temperature different from the ambient in the field of view
Data Source
AI summary
A motion detector system including first and second pairs of pyro-electric elements, electrical interconnections between the pyro-electric elements in the first pair providing a first signal output and local temperature compensation for the elements in the first pair, electrical interconnections between the elements in the second pair providing a second signal output and local temperature compensation for the pyro-electric elements in the second pair, wherein the compensation for the first pair is independent of the compensation for the second pair, a housing enclosing the two pairs of pyro-electric elements and defining a window, only one of the pyro-electric elements in each pair viewing a motion detection field of view through the window, and a signal processor receiving the first and second signal outputs and providing an output indication of crossing the field of view by an object having a temperature different from the ambient in the field of view.