Adjustable Motion Detector Using Rotating Fresnel Lens
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Solution Overview
Problem
Decorative lighting fixtures with passive infra-red motion detectors face challenges in adjusting the field of view to accommodate varying installation heights and distances, as a single fixed motion detector cannot effectively monitor walkways or driveways at different elevations or distances from the fixture.
Innovation Solution
A decorative lighting fixture with a hidden motion detector featuring a slotted decorative element and a segmented Fresnel lens array, allowing for adjustable fields of view by rotating the lens array relative to the slots, enabling selection of different ranges through user-controlled alignment of lens columns and slots, preserving a decorative appearance while providing adjustable detection zones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed motion detector is used in decorative fixtures, then the device complexity is reduced and manufacturing is simplified, but the adaptability to different installation scenarios (varying heights and distances) deteriorates
Solution Approach 1:
The motion detector is made adjustable through rotary movement, allowing the field of view to be dynamically changed according to different installation scenarios. The lens array can rotate relative to the slots to select between multiple detection ranges, transforming a static device into a dynamic one that adapts to varying heights and distances.
Solution Approach 2:
The lens array is segmented into multiple columns that can be independently positioned. Each column corresponds to a specific detection range, allowing the system to select different segments (columns) by rotating the lens array, thereby achieving multiple fields of view without requiring multiple complete detectors.
2Shape
If the motion detector is hidden in the fixture body for aesthetic purposes, then the appearance quality is improved, but the ease of adjustment and operation deteriorates
Solution Approach 1:
A control mechanism serves as an intermediary between the user and the hidden motion detector. The control allows users to adjust the lens array position without needing to access or understand the internal detector components, maintaining aesthetic appearance while enabling easy operation through a simple external interface.
3Adaptability or versatility
If multiple fields of view are provided for different ranges, then the adaptability to various distances is improved, but the device complexity and manufacturing cost increases
Solution Approach 1:
A single motion detector unit performs multiple functions by detecting motion at different ranges. The rotatable lens array allows one detector to serve multiple detection purposes (close range, medium range, long range), eliminating the need for multiple separate detectors and reducing overall manufacturing costs.
Solution Approach 2:
Instead of providing multiple static detectors for different ranges, the system uses one dynamic detector that can rotate to select different detection ranges. This dynamic approach reduces the number of components needed while maintaining the capability to detect motion at various distances.
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 allows for cost-effective manufacture of decorative fixtures with adjustable motion detectors that can be hidden within the fixture body, offering customizable fields of view to suit different installation scenarios without compromising the aesthetic appeal, ensuring effective monitoring of areas at various distances and elevations.
Implementation Method 1
passive infra-red (PIR) motion detectors
Implementation Method 2
a segmented Fresnel lens array is disposed within the housing behind the slots to direct infra-red energy from a monitored field of view to a sensor
Data Source
AI summary
A motion-activated decorative lighting fixture with a PIR motion detector having an adjustable field of view hidden behind a decorative slotted wall of the fixture body. The lighting fixture includes a motion detector housing that forms an integral part of the fixture body. The housing includes a slotted vertically extending exterior wall around the housing with an array of elongate vertically extending slots horizontally spaced apart from one another and extending along at least a portion of the wall. One or more PIR sensors are disposed within the housing, and a segmented Fresnel lens array is disposed within the housing behind the slots to direct infra-red energy from a monitored field of view to a sensor. The lens array includes a plurality of columns of lenslets, which are divided into at least two sets of columns, the columns of the first set alternating with the columns of the second set so as to form an alternating sequence of columns. At least a portion of the columns of each set have at least two lenslets disposed one above the other. Each column is aligned with a corresponding slot so as to direct infra-red energy from a monitored zone passing through the corresponding slot to a sensor. The configuration defines an optical path for infra-red energy emanating from a detection zone in the field of view, the optical path passing through a given slot and a lenslet aligned with the slot and on to a PIR sensor. The lens array and the wall are mounted for relative rotary movement with respect to one another between at least a first position and a second position. The columns and slots are disposed such that in the first relative position of the lens array and slots each column of the first set is aligned with a corresponding slot while the columns of the second set are substantially blocked by the wall. In the second position each column of the second set is aligned with a corresponding slot and the columns of the first set are substantially blocked by the wall. In this way the lenslets of the columns of the first and second sets define alternative fields of view that may be switched in at the user's choice.