Ceiling Mount PIR Detector with Adjustable Mirror for Height Variations
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Solution Overview
Problem
Ceiling mount intrusion detectors with passive infrared (PIR) sensors face performance issues due to uncertainty in mount height, as existing detectors with adjustable mechanisms use Fresnel lenses instead of mirrors, which limits their operational range and effectiveness across varying ceiling heights.
Innovation Solution
A ceiling mount intrusion detector equipped with a passive infrared (PIR) mirror and an adjustable mount height mechanism that allows the mirror to be moved vertically to maintain optimal energy collection and detection performance across a wider range of ceiling heights by compensating for changes in ceiling height, using a mechanism similar to adjusting a zoom lens without rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a fixed PIR optical system with Fresnel lens is used, then the detector can be manufactured simply, but the detection performance varies significantly with mount height
Solution Approach 1:
The patent applies the dynamics principle by replacing the fixed Fresnel lens with a movable mirror that can be adjusted to different positions. The mirror assembly includes a mirror element mounted on a movable support structure that allows vertical adjustment along the optical axis. This dynamic adjustment capability enables the optical system to adapt to different mount heights while maintaining consistent detection performance, resolving the contradiction between manufacturing simplicity and performance reliability.
2Adaptability or versatility
If the mount height range is extended to cover more ceiling heights, then the detector becomes more versatile, but the detection performance deteriorates at extreme heights
Solution Approach 1:
The patent applies parameter changes by adjusting the position of the mirror element along the optical axis to compensate for variations in mount height. The mirror can be moved to different vertical positions to optimize the optical path for different ceiling heights. This parameter adjustment allows the detector to maintain consistent detection performance across an extended mount height range of 2.4m to 4.8m, resolving the contradiction between versatility and performance reliability at extreme heights.
3Reliability
If a mechanism to adjust mount height is added, then the detector can operate reliably across different ceiling heights, but the device complexity increases
Solution Approach 1:
The patent applies mechanics substitution by replacing complex mechanical adjustment mechanisms with a simpler mirror-based optical adjustment system. Instead of moving the entire detector assembly or using complex lens adjustment mechanisms, the invention uses a movable mirror element that can be adjusted to different positions to compensate for mount height variations. This substitution reduces device complexity while maintaining reliable detection performance across different ceiling heights.
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 solution ensures consistent and improved detection performance across a broader ceiling height range, maintaining good performance even when the ceiling height varies by up to 2 meters, and allows the detector to operate effectively within the mount height range of 3.3m-5.3m, achieving average peak-to-valley ratios above 0.5µW for clear alarm signal identification.
Implementation Method 1
a passive infrared (PIR) mirror
Implementation Method 2
The ceiling mount intrusion detector includes a PIR sensor and a mirror positioned between the PIR sensor and the ceiling
Data Source
Figure 1A~1C
Figure 2
Figure 3
AI summary
A ceiling mount intrusion detector is provided that includes a sensor, a mirror for directing collected energy towards the sensor, and a mechanism for adjusting the mirror to account for a plurality of different mount heights. In some embodiments, the mechanism can adjust the mirror by moving the mirror up or down without rotating the mirror.