Hemispherical Dome Passive Infrared Detector for High-Area Coverage
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Solution Overview
Problem
Current passive infrared detectors are ineffective at accurately detecting the presence and absence of personnel from a large distance, such as in high warehouses, due to their design limitations which result in unreliable energy savings and increased energy consumption.
Innovation Solution
A passive infrared detector with a substantially hemispherical dome formed by contiguous facets with flat outer surfaces, featuring multiple Fresnel lenses and sensors arranged to collect infrared radiation from a wide range of directions without obstructing the detection field, and electronic logic to generate a detection signal only when multiple sensors detect radiation, reducing false positives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional passive infrared detector design is used, then the device structure is simple, but the detection precision deteriorates at large distances
Solution Approach 1:
The detector is divided into multiple sensor elements (first sensor element and second sensor elements) with distinct functions. The first sensor element detects infrared radiation along the central axis, while the second sensor elements detect radiation from off-axis directions. This segmentation allows each element to be optimized for its specific detection role, improving overall detection precision at large distances without requiring a single overly complex sensor design.
Solution Approach 2:
The invention transitions from a single-axis detection approach to a multi-dimensional detection scheme by adding second sensor elements that detect infrared radiation from different angular directions (off-axis). This dimensional expansion in the angular domain enables the detector to accurately sense personnel presence at large distances by combining information from multiple detection dimensions, thereby improving measurement precision without excessive complexity.
2Area of stationary object
If the detector is mounted at high altitude in warehouses, then the coverage area increases, but the detection reliability deteriorates
Solution Approach 1:
The detector achieves multi-functionality by combining first sensor elements for on-axis detection with second sensor elements for off-axis detection. This universal detection capability allows a single detector mounted at high altitude to reliably cover large warehouse areas by sensing infrared radiation from personnel regardless of their position relative to the detector, maintaining detection reliability across expanded coverage areas.
Solution Approach 2:
The invention changes the detection parameters by introducing sensor elements with different angular sensitivities. The second sensor elements are specifically oriented to detect infrared radiation from off-axis directions, changing the angular parameter of detection. This parameter change enables reliable detection across large coverage areas at high mounting altitudes by capturing radiation from a broader spatial distribution.
3Measurement precision
If multiple sensor elements are added to improve detection accuracy, then the detection precision improves, but the device complexity increases
Solution Approach 1:
The multiple sensor elements are segmented into distinct functional groups: first sensor elements for on-axis detection and second sensor elements for off-axis detection. This segmentation allows for modular design and simplified signal processing, where each group handles specific detection tasks. The segmentation reduces the complexity burden of having multiple sensors by organizing them into manageable, functionally-distinct units that can be processed independently.
Solution Approach 2:
The invention uses a selective and partial approach to multi-sensor implementation by deploying second sensor elements only in directions where off-axis detection is needed, rather than implementing a complete omnidirectional array. This partial action achieves sufficient detection precision for warehouse applications without the excessive complexity of a fully redundant multi-sensor system, optimizing the balance between precision and complexity.
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 detector effectively covers a wide area, ensuring reliable detection of personnel presence and absence even from significant heights, reducing energy consumption by only activating lighting when necessary and minimizing false alarms.
Implementation Method 1
A passive infrared detector with a substantially hemispherical dome formed by contiguous facets with flat outer surfaces, featuring multiple Fresnel lenses and sensors arranged to collect infrared radiation
Implementation Method 2
passive infra red sensors arranged to collect infrared radiation from a wide range of directions
Data Source
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AI summary
A passive infra red detector comprises a plurality of passive infra red sensors (4, 5) and a lens member (2) arranged to direct radiation from a target area onto the sensors. The lens member (2) forms a substantially hemispherical dome about the infra red sensors (4, 5). The dome has a central axis and a plurality of contiguous facets (2a -2g) distributed about the central axis. Each facet has a flat outer surface and an inner surface that forms a lens to direct radiation onto the sensors. The detector further comprises a first passive infra red sensor (4) aligned with the central axis of the dome and having a sensitive surface substantially normal to the central axis, and a plurality of second passive infra red sensors (5) distributed about the central axis of the dome. The second passive infra red sensors (5) are inclined such that the outward normal from the sensitive surface of each second passive infra red sensor (5) makes an acute angle with the outward direction of the central axis. The detector is capable of detecting movement of people within a wide region from a significant height above that region.