Infrared Motion Detector Lens and Light Guide Design
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Solution Overview
Problem
Conventional infrared motion detectors face limitations in detecting ambient brightness, IR remote control signals, and LED light signals due to optical shading and transmission losses, especially when using domes or fiber optic rods, which affect the reliability and recognition of these signals.
Innovation Solution
The design incorporates a rectangular lens arrangement with dome-shaped or truncated cone-shaped lenses, a central plastic web with light channels, and a mirror arrangement to enhance optical resolution and signal detection, allowing for symmetrical and unrestricted detection and output of signals, while the snap-in connection and light guides improve manufacturing efficiency and reduce shading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If signals are routed through the lens body, then the lens structure is simple, but transmission losses occur and detection reliability is reduced
Solution Approach 1:
The device is divided into two separate optical paths: one through the lens body for motion detection, and another through dedicated light guides for ambient brightness and LED signal detection. This segmentation allows each component to be optimized for its specific function without compromising the other, eliminating transmission losses while maintaining structural simplicity.
Solution Approach 2:
Dedicated light guides are introduced as intermediary components to transmit ambient brightness and LED signals separately from the main lens body. These light guides act as specialized mediators that ensure reliable signal transmission without the transmission losses experienced when routing signals through the lens body material.
2Reliability
If a dome-shaped lens protrudes from the housing, then unimpeded motion detection is achieved, but optical shading occurs limiting ambient brightness and LED signal detection
Solution Approach 1:
The optical detection system is segmented into separate channels: the dome-shaped lens handles motion detection while dedicated light guides handle ambient brightness and LED signal detection. This allows the dome to maintain its protruding shape for unimpeded motion detection without causing optical shading for other detection functions.
Solution Approach 2:
The solution moves the ambient brightness and LED signal detection paths to a different spatial dimension by routing them through dedicated light guides that are positioned separately from the main lens axis. This dimensional separation allows the dome-shaped lens to protrude without blocking the optical paths for other functions.
3Shape
If tinted lenses are used, then appearance is improved, but ambient light detection and LED signal output become inadequate
Solution Approach 1:
The optical system is segmented so that the lens body can be tinted for aesthetic purposes while dedicated transparent light guides handle ambient brightness and LED signal detection. This allows the lens to maintain its attractive tinted appearance without compromising the detection capabilities, as the light guides are specifically designed for optical transmission.
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 enables improved detection of ambient brightness, enhanced IR remote controllability, and clear LED light signal recognition, addressing the limitations of previous designs by ensuring unobstructed signal transmission and increased optical resolution.
Implementation Method 1
passive infrared sensors, in which heat radiation emitted by people is focused via an externally visible lens and directed onto internal passive infrared sensors
Implementation Method 2
heat radiation emitted by people is focused via an externally visible lens and directed onto internal passive infrared sensors
Implementation Method 3
an (active) infrared receiver and a signal LED can be integrated into the presence detector's housing to trigger certain actions... or to visibly transmit status information to the outside
Implementation Method 4
corresponding ambient light sensors are integrated into the motion detector. The light is either directed through the lens or via a specially designed light guide
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The invention relates to a passive infrared motion detector comprising a base part (9) which holds a printed circuit board (7) with at least four passive IR sensors (8), IR receiver (7.1), brightness sensor (7.3) and further electronic components, a mirror arrangement (5) and a rectangular lens arrangement (3). The base part (9) is covered by a cover part (1), wherein preferably four spherical-cap-shaped and/or frustum-shaped lenses (3.1) with in each case a plurality of lens segments for registering motion are arranged in the corner regions of the rectangular lens arrangement (3). The mirror arrangement are arranged under the lens arrangement (3) is provided to increase the optical resolution of the lens arrangement (3), wherein the effective surfaces (5.1) of said mirror arrangement are provided with a reflecting coating. The cover part (1) situated over the lens arrangement (3) comprises a centrally arranged plastic web (1.1) with at least two openings (1.3), into which transparent cap parts (2) are inserted. Light channels (5.2), (5.3), which interact with the IR receiver (7.1) and brightness sensor (7.3) lying therebelow, are arranged under the cap parts (2).