Reflective PIR Sensor Tiers for Signal Strength Consistency
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Solution Overview
Problem
Existing reflective type PIR motion detection systems face challenges in ensuring that sensing signals from different positions have similar strengths, as the design of reflecting surfaces fails to accurately focus infrared radiation from far and near positions onto the sensor element effectively.
Innovation Solution
The system incorporates a reflecting element with multiple tiers, where each reflecting curved surface has an aperture width correlated with the reciprocal of its azimuth angle and an aperture length correlated with the square of the distance from the corresponding sensed position, ensuring that infrared rays from various positions are reflected onto the sensor element with similar signal strengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional reflecting surfaces are used in PIR motion detection systems, then the system can detect infrared radiation from organisms, but sensing signals from far and near positions have different strengths, reducing detection accuracy
Solution Approach 1:
The reflecting element is divided into multiple reflecting tiers, with each tier having reflecting curved surfaces with specifically designed aperture widths and lengths tailored to their local azimuth angles and distances from the sensor element. This local customization of geometric parameters ensures that infrared radiation from different positions is focused with equal irradiance onto the sensor element, resolving the signal strength inconsistency problem.
2Ease of manufacture
If the reflecting element uses uniform aperture design for all reflecting surfaces, then manufacturing is simplified, but infrared radiation from different positions cannot be focused effectively onto the sensor element
Solution Approach 1:
The reflecting element is segmented into multiple reflecting tiers (first reflecting tier, second reflecting tier, etc.), with each tier containing multiple reflecting curved surfaces. Each segment is assigned specific aperture width and length parameters based on its azimuth angle and distance characteristics, allowing precise infrared focusing while maintaining a modular structure that facilitates manufacturing.
3Adaptability or versatility
If reflecting curved surfaces are arranged to cover wide azimuth angles, then the detection field of view is expanded, but the aperture area must be reduced, weakening the sensing signal
Solution Approach 1:
The aperture width and length of each reflecting curved surface are dynamically adjusted as functions of the azimuth angle and distance from the sensor element. Specifically, aperture width is set proportional to the reciprocal of the cosine of the azimuth angle, and aperture length is set proportional to the square of the distance. This parameter optimization ensures that reflecting surfaces at larger azimuth angles maintain sufficient aperture area to collect and focus infrared radiation with equal irradiance, thereby maintaining strong sensing signals across a wide detection field of view.
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 design enhances the sensing capability of the PIR motion detection system by ensuring that infrared rays from different positions are reflected with equal irradiance, improving the system's ability to detect motion from both near and far distances.
Implementation Method 1
The reflecting curved surfaces respectively have different azimuth angles relative to a third axial direction and are adapted to respectively reflect infrared rays from different sensed positions onto the sensor element
Implementation Method 2
A passive infrared (PIR) detection system utilizes this phenomenon for sensing the infrared radiation emitted from organisms, so as to detect whether someone has entered a specific space
Data Source
AI summary
A reflective type passive infrared motion detection system includes a housing, a sensor element and a reflecting element. The sensor element is disposed on the housing. The reflecting element is disposed on the housing and has a plurality of reflecting tiers. Each reflecting tier has a plurality of reflecting curved surfaces, the reflecting curved surfaces are arranged along a first axial direction in sequence, and the reflecting tiers are arranged along a second axial direction in sequence. The reflecting curved surfaces respectively have different azimuth angles. An aperture width of each reflecting curved surface along a direction perpendicular to the second axial direction is positively correlated with a reciprocal of a cosine value of the corresponding azimuth angle. An aperture length of the reflecting curved surfaces of each tier along a direction of the second axial direction is positively correlated with square of a distance of the corresponding infrared source.