PIR Motion Detector with Multi-Level LED Indication
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Solution Overview
Problem
Passive infrared motion detectors often experience false triggers due to transient temperature changes caused by events other than object movement, such as wind or changes in cloud cover, leading to undesirable activation of lighting or security alerts, and require careful aiming to minimize these false triggers, which compromises sensitivity.
Innovation Solution
Implementing a motion detector with multiple response levels of sensitivity using pyroelectric infrared sensors and circuitry that generates varying output signals, indicated by LED lights or auditory systems, with a lens system transparent to infrared and translucent to visible light, allowing for staged responses based on signal strength compared to multiple reference levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If PID sensitivity is maximized to improve motion detection capability, then detection precision is improved, but false trigger rate increases due to peripheral events
Solution Approach 1:
The patent segments the detection field into a central coverage area and peripheral zones. The PID is aimed to direct the central coverage area toward the intended monitoring zone, while peripheral zones are separately monitored with reduced sensitivity thresholds. This segmentation allows the system to maintain high sensitivity for genuine motion in the central area while filtering out false triggers from peripheral events such as wind-blown foliage or distant temperature variations.
2Reliability
If PID sensitivity is reduced to minimize false triggers, then false trigger rate decreases, but motion detection capability is compromised
Solution Approach 1:
The patent applies local quality by implementing different sensitivity thresholds for different spatial zones. The central coverage area maintains high sensitivity to detect genuine motion events, while peripheral zones use lower sensitivity thresholds to prevent false triggers. This localized differentiation of detection parameters allows each zone to operate optimally for its specific function, resolving the contradiction between overall sensitivity and false trigger reduction.
3Reliability
If careful aiming is performed to minimize false triggers, then false trigger rate decreases, but installation time increases
Solution Approach 1:
The patent incorporates preliminary action by providing adjustment mechanisms and visual aids during installation that guide the installer in achieving proper aiming. These aids allow installers to quickly identify and adjust the central coverage area orientation without requiring extensive trial-and-error or specialized expertise. The system is designed to be easily configured during installation, reducing the time investment required to achieve optimal performance while maintaining low false trigger rates.
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 reduces false triggers by providing clear indicators of signal strength, allowing for precise adjustment of sensitivity levels, enhancing the accuracy of motion detection and reducing unnecessary activations while maintaining maximum sensitivity.
Implementation Method 1
Motion detectors based on infrared sensing elements represent a specialized type of passive infrared (PIR) sensor called Passive Infrared-based Motion Detectors (PID)... The sensor elements in PIDs produce what is basically an analogue signal subject to variation over time depending upon changes in the heat output, or reflection, within its field of view
Implementation Method 2
A lens system will typically be used to define the field of view and concentrate infrared energy onto the sensor element. The lens system can double for back screen projection of the indicator light output if it is translucent to visible light and transparent to infrared light
Data Source
AI summary
An apparent motion detector is provided with multiple response levels at differing degrees of sensitivity. The motion detector is based on use of a pyroelectric infrared sensor and conventional circuitry which generates an output signal the strength of which reflects transient temperature changes occurring within a field of view and distinguishable from background heat levels. The detector's response varies with the strength of the signal using a plurality of LED's which emit different colors or are driven at different intensities. The system generally will have a field of view defined by a lens system which is translucent to visible light and transparent to infrared. The lens system doubles as a back screen projection system for display of the indicator light.