Elevator Door Safety System with PIR Motion Sensor
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Solution Overview
Problem
Current elevator door safety technologies are inadequate in preventing pinch-related injuries, as they often fail to detect objects or people in time, and existing solutions like light curtains are expensive and prone to false triggers or damage.
Innovation Solution
A sensor system comprising a motion sensor and a proximity sensor, integrated into a fire-rated elevator entrance assembly, which detects the presence of people and monitors door status to prevent doors from closing fully, thereby reducing the risk of pinch injuries and false triggers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a light curtain is installed on the hallway face to detect objects before the pinch zone, then detection capability is improved, but installation cost and complexity increase significantly
Solution Approach 1:
The patent uses a pyroelectric infrared sensor that detects infrared radiation patterns characteristic of human movement, creating a simplified sensory copy of the detection function provided by expensive light curtains. This allows the system to achieve similar safety detection capabilities through a more economical sensor approach.
Solution Approach 2:
The patent replaces the mechanical/optical light curtain system with an infrared sensing system that detects thermal radiation from moving objects. This substitution uses thermal field detection instead of optical field detection, achieving comparable safety function with simpler, less expensive hardware.
2Device complexity
If a single PIR sensor is used to detect moving objects in the entrance area, then device complexity is reduced, but false triggering increases due to sensitivity to air currents
Solution Approach 1:
The patent configures the PIR sensor with specific aperture parameters (aperture angle, distance from door panel) to create a focused detection zone that prioritizes sensitivity to horizontal movement patterns typical of approaching persons while reducing sensitivity to vertical air currents. This localized optimization of sensor parameters improves reliability without increasing complexity.
Solution Approach 2:
The system performs preliminary analysis of the infrared signal characteristics to distinguish between patterns caused by approaching persons and those caused by air currents. By evaluating the temporal and spatial characteristics of detected infrared radiation before triggering a door open command, the system reduces false positives while maintaining simple hardware configuration.
3Reliability
If the detection area is extended closer to the door panel to prevent pinch injuries, then safety is improved, but the system becomes more susceptible to false triggers from air currents
Solution Approach 1:
The patent optimizes the aperture parameters of the PIR sensor to create a detection pattern that is highly sensitive to the specific spatial and temporal characteristics of human approach movements while being less sensitive to the broader environmental factors like air currents. This localized detection optimization allows closer positioning without proportionally increasing false trigger rates.
Solution Approach 2:
The control system implements preliminary signal validation that analyzes the detected infrared patterns before triggering door reopening. By evaluating whether the detected signal matches the expected pattern of an approaching person versus environmental interference, the system can safely extend the detection area closer to the door while maintaining false trigger resistance.
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 system effectively reduces the number of pinch-related injuries by ensuring doors remain open until it is safe for passengers to enter or exit, tailored to each floor and landing, and is designed for easy installation and compliance with safety standards.
Implementation Method 1
A single pyroelectric infrared (PIR) sensor in the elevator entrance detects objects or persons moving in an entrance area
Data Source
AI summary
An elevator door safety system has a motion sensor and a proximity or door sensor defined in a fire-rated elevator entrance assembly. The sensors work together to determine when to open a closing door. The invention further defines a method of controlling an elevator door providing a motion sensor and providing a door sensor, wherein signals from each sensor are sent to a control board to determine when to open elevator doors in response to detecting a person in a detection area in an elevator entrance area.