Optical Door Detection System for Elevator Tamper Resistance
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Solution Overview
Problem
Elevator systems face safety risks due to tampering with door switches, where hoistway and car doors are not properly closed before the elevator moves, leading to potential hazards.
Innovation Solution
A door detection system using a transmitter-receiver setup on the elevator car door and a reflector on the hoistway door, with processors to ensure both doors are properly closed by transmitting and receiving signals, and sending instructions to keep the elevator stationary if either door is not in the correct position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If door switches are used to detect door closure, then the system is simple and easy to operate, but the system is vulnerable to tampering and disabling
Solution Approach 1:
The patent introduces an optical intermediary system consisting of transmitters, receivers, and reflectors that mediate between the door closure state and the control system. This optical mediator is positioned on door surfaces and detects closure through light signal reflection, providing a tamper-resistant detection mechanism that does not rely on easily disableable electrical switches.
Solution Approach 2:
The patent replaces the mechanical/electrical switch-based door detection system with an optical detection system. Instead of using electrical contacts that can be shorted or disabled, the system uses optical transmitters and receivers that detect door closure through light reflection, making tampering significantly more difficult.
2Reliability
If additional detection means are added to prevent tampering, then safety is improved, but device complexity increases
Solution Approach 1:
The patent merges the door closure detection function with the existing door structure by integrating transmitters, receivers, and reflectors directly onto the door surfaces. This integration approach combines the detection functionality with the structural components, adding safety without requiring separate, complex detection systems.
Solution Approach 2:
The optical detection system serves multiple functions: it detects car door closure, detects hoistway door closure, and provides tamper resistance. By using a universal optical detection mechanism for both door types, the system achieves enhanced safety without proportionally increasing complexity.
3Reliability
If optical transmitters and receivers are positioned on doors, then tampering detection is improved, but installation complexity increases
Solution Approach 1:
The patent positions the transmitters, receivers, and reflectors on the door surfaces during the door manufacturing or assembly process. This preliminary positioning ensures proper alignment and integration before the door is installed in the elevator system, simplifying the overall installation process while maintaining high detection accuracy.
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
Enhances safety by reliably detecting the closure of both elevator car and hoistway doors, preventing the elevator from moving unless both are properly closed, thus reducing the risk of accidents.
Implementation Method 1
the first signal is an infrared light beam
Implementation Method 2
a reflector positioned on the hoistway door substantially opposite the second transmitting and receiving face when the elevator car door and the hoistway door are closed
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
In an embodiment, a door detection system may include a transmitter, a receiver, a reflector, and one or more processors. The transmitter positioned on an elevator car door transmits a signal towards a reflector on a hoistway door and the reflector reflects the signal towards the receiver when the hoistway door is properly positioned with respect to the elevator door. The one or more processors determine whether the hoistway door is properly positioned with respect to the elevator car door based on the reflected signal received by the receiver. If the hoistway door is not properly positioned, the elevator car is prevented from moving. If the hoistway door is properly positioned, the elevator car is free to move.