Time of Flight Sensor Door Contact System
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Solution Overview
Problem
Reed and magnet technology-based door and window contact systems face limitations in gap distance, security vulnerability, and cost, particularly when trying to monitor partially opened windows, which can compromise detection and increase overall expenses.
Innovation Solution
The implementation of time of flight sensors with a microcontroller unit and intelligent signal analysis algorithms, allowing for wireless or wired communication, and the ability to determine door or window movement and potential tampering, while enabling user-defined monitoring settings without the need for expensive magnets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If reed and magnet technology is used to detect door and window contact, then the system is inexpensive to implement, but the maximum functional gap between electrical contacts is limited and mounting on ferrous metal surfaces reduces the operating gap
Solution Approach 1:
The patent replaces the mechanical reed switch and magnet system with an optical time-of-flight sensing system. TheToF sensor uses light propagation to detect the presence and position of door/window frames, eliminating the need for physical magnetic contacts and their associated gap limitations. This substitution resolves the contradiction by enabling larger detection gaps without requiring expensive wide-gap magnets.
Solution Approach 2:
The patent changes the detection parameter from magnetic field interaction (limited by gap distance) to optical time-of-flight measurement (effective over larger distances). By measuring the time for light to travel to and from the target object, the system can detect contact status across gaps that would be too large for reed switches, while maintaining cost-effectiveness through the use of TOF sensor technology.
2Reliability
If reed and magnet technology is used, then the system is simple to implement, but it is vulnerable to attempts to defeat the system by introducing magnets in close proximity
Solution Approach 1:
The patent replaces the magnetic detection system with an optical time-of-flight sensing system. Since TOF sensors detect objects using light propagation and flight time measurement rather than magnetic fields, they are inherently immune to magnetic spoofing attacks. An intruder cannot defeat the system by introducing magnets, as the optical sensor detects the physical presence and position of objects through light reflection and travel time, fundamentally changing the detection mechanism to one that cannot be easily compromised by magnetic interference.
Solution Approach 2:
The patent introduces light as an intermediary medium for detection, replacing direct magnetic field interaction. The TOF sensor emits light pulses that reflect off target objects and return to the sensor, with the detection based on the time of flight. This intermediary optical mechanism provides inherent security because it detects physical presence through a different physical domain (optical rather than magnetic), making magnetic defeat attempts ineffective while adding minimal system complexity.
3Adaptability or versatility
If the maximum functional gap of the reed switch is exceeded to monitor partially opened windows, then a bypass mode can be invoked, but this compromises perimeter intrusion detection
Solution Approach 1:
The patent changes the detection parameter from binary magnetic contact (open/closed only) to continuous optical distance measurement. The TOF sensor can measure the exact distance to the door or window frame at any position, enabling the system to detect partial openings, fully open positions, and closed positions with precision. This continuous measurement capability allows the system to monitor partially opened windows without invoking bypass mode, maintaining full perimeter intrusion detection capability while providing versatile positioning information.
Solution Approach 2:
The patent transitions from a static binary detection system (reed switch that only detects contact or no contact) to a dynamic measurement system (TOF sensor that continuously measures distance). The TOF sensor can track the position of doors and windows as they move through various opening degrees, providing real-time feedback on the exact state of the perimeter. This dynamic capability allows the system to adapt to partial opening scenarios while maintaining security, as the continuous distance data enables intelligent decision-making about when to trigger alerts versus when to simply log the position.
4Reliability
If a magnet is installed in the reed and magnet system, then the system can function, but the overall cost increases
Solution Approach 1:
The patent replaces the magnet component entirely with an optical time-of-flight sensing system. The TOF sensor uses integrated light-emitting diodes and photodetectors to detect the presence and position of objects through light propagation. This eliminates the need for separate magnets, reed switches, and associated magnetic components, reducing the bill of materials cost while maintaining reliable detection functionality. The optical system achieves the same detection goal without the magnetic components that drive up cost.
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 solution enhances the robustness and security of door and window contact systems by accurately detecting movement and tampering attempts without increasing overall costs, allowing for reliable monitoring of partially opened positions and reducing the risk of system defeat.
Implementation Method 1
door and window contact systems and methods that include time of flight sensors
Data Source
AI summary
Systems and methods that address the gap, security, and robustness limitations of known door and window contact systems and methods without increasing the overall cost thereof are provided. A system can include a time of flight sensor for mounting in or on a first portion of a window unit or a door unit and a microcontroller unit in communication with the time of flight sensor. The sensor can measure a time for a signal to travel from the sensor to a second portion of the window unit or the door unit and back to the sensor, the sensor can transmit the measured time to the microcontroller unit, and the microcontroller unit can use the measured time to make a security determination.