Linear Infrared Detector Array for Motion Sensing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional motion sensors using infrared detectors face challenges in distinguishing between human movement and stationary objects, leading to false alarms, particularly in occupancy detection scenarios where sensitivity and false alarm rejection are critical.
Innovation Solution
The use of a linear array of infrared detector elements with multiple curtains of monitored volumes, tilted at an angle, and level-sensitive detectors to generate zero-frequency signals, allowing for improved occupancy detection and motion confirmation while suppressing false reports from stationary objects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional infrared detectors are used to detect motion, then motion detection capability is provided, but false alarms occur due to inability to distinguish between human movement and stationary objects
Solution Approach 1:
The detection space is divided into multiple curtains of monitored volumes that are tilted at an angle. Each curtain corresponds to specific detector elements in the linear array, creating segmented monitoring zones that track movement through space sequentially rather than as a single undifferentiated detection area.
Solution Approach 2:
The patent introduces a spatial dimension by tilting the curtains of monitored volumes at an angle relative to the detector array. This angular orientation creates a directional component to motion detection, allowing the system to distinguish between objects moving through different spatial paths and thereby differentiate human movement patterns from stationary objects.
2Measurement precision
If sensitivity to small movements is increased for occupancy detection, then occupancy detection capability is improved, but false alarms from stationary objects increase
Solution Approach 1:
The system employs dynamic monitoring through multiple tilted curtains that capture movement sequences over time. Rather than relying on a single static detection threshold, the system analyzes the temporal and spatial dynamics of detected signals across multiple curtains, identifying patterns consistent with human movement while filtering out stationary object signatures.
Solution Approach 2:
The processing circuitry analyzes signals from multiple detector elements in sequence as movement progresses through the tilted curtains. This sequential feedback mechanism allows the system to confirm occupancy by verifying consistent signal patterns across multiple detection zones, thereby reducing false alarms from stationary objects that would not produce sequential signal changes.
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 configuration enhances the sensitivity to human movement while reducing false alarms, enabling effective occupancy detection and motion direction determination with a higher tolerance for stationary object signals.
Implementation Method 1
An infrared detector detects changes in mid-infrared (IR) radiation having a wavelength of about 6-14 microns. These changes are due to temperature differences between a warm object, such as a warm blooded animal, and its background environment as the warm object moves through that environment.
Implementation Method 2
A typical PIR detector utilizes a pyroelectric or piezoelectric substrate with a detector element that consists of conductive areas on opposite sides of the substrate acting as a capacitor. As the substrate changes temperature, charge is added or subtracted to the capacitor, changing the voltage across the capacitor.
Implementation Method 3
The optical array directs the IR radiation from multiple monitored volumes onto the infrared detector and sometimes includes filters to minimize the radiation outside of the desired mid-infrared range from reaching the infrared detector. Concentrations of radiation from each of the pyramids are projected by the optical arrays onto the infrared detector where they are superimposed.
Implementation Method 4
Many motion sensors incorporate an optical array (made of optical elements such as lenses, focusing mirrors, and so on) to be able to monitor a large space with a single infrared detector.
Data Source
AI summary
A motion sensor includes an infrared detector having a single linear array of at least four detector elements disposed on a substrate. The motion sensor also includes an optical system to simultaneously direct electromagnetic energy from two or more curtains of monitored volumes onto the linear array of detector elements. The two or more curtains of the monitored volumes having a tilt angle from a vertical orientation of the motion sensor to create a quadrature horizontal spatial relationship between the monitored volumes. Signals from the linear array of detector elements are then processed to detect a quadrature phase relationship between the signals, and an indication of human presence is provided if a quadrature phase relationship is found.