Door Position Sensor for Electromagnetic Lock
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Solution Overview
Problem
Current door position sensors used in electromagnetic door locks require excessive door movement before detecting initial movement away from the door frame, leading to a false impression of insecurity, especially in De-Mag and Eco-Mag architectures, and there is a need for a more compact and sensitive detection system.
Innovation Solution
A door position sensor system that includes a permanent magnet fixably connected to the door and a sensor on or in the electromagnet, capable of detecting movement of the door away from the door frame within ⅛ inch, using Hall Effect sensors or reed switches, and a strike tray with indicia for proper alignment, allowing early detection of door movement while the strike plate remains in contact with the electromagnet.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a door position sensor requires excessive door movement before detecting initial movement, then the detection system is simpler and more robust, but it creates a false impression of insecurity and delays security response
Solution Approach 1:
The door movement detection is segmented into multiple stages: initial movement detection (within 1/8 inch) using the permanent magnet and sensor, followed by subsequent movement detection. This segmentation allows the system to trigger security responses at the earliest stage of door opening while maintaining overall system robustness.
Solution Approach 2:
The permanent magnet is pre-positioned in close proximity to the sensor (within 1/8 inch) to enable preliminary detection of initial door movement. This preliminary action allows the system to detect door opening attempts before the door moves significantly, creating an early warning signal for security purposes.
2Measurement precision
If the permanent magnet and sensor are positioned in close proximity (within 1/8 inch), then detection sensitivity is improved, but the device complexity and alignment precision requirements increase
Solution Approach 1:
The permanent magnet is merged with the strike plate assembly, and the sensor is integrated into the electromagnet housing. This merging reduces the number of separate components and simplifies the overall device structure while maintaining the close proximity (within 1/8 inch) necessary for high detection sensitivity.
Solution Approach 2:
The strike plate serves multiple functions: it provides the mechanical interface for door closing and simultaneously houses the permanent magnet for position sensing. Similarly, the electromagnet housing serves both as the electromagnetic actuator and as the mounting structure for the position sensor. This multi-functionality reduces device complexity.
3Strength
If the strike plate is movably mounted to allow controlled door movement, then the lock can withstand physical blows better, but the door position detection becomes more challenging
Solution Approach 1:
The permanent magnet acts as an intermediary between the door and the sensor. It is rigidly attached to the door, so it moves with the door even when the strike plate allows controlled movement. This intermediary enables accurate detection of initial door movement despite the movable strike plate configuration that provides blow 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 provides a more sensitive and robust detection of initial door movement, enhancing security by triggering a door-opening signal earlier and allowing for precise power management in Eco-Mag and De-Mag designs, while maintaining a compact and convenient package.
Implementation Method 1
a permanent magnet fixably connected to the door and a sensor on or in the electromagnet, wherein movement of the door away from the door frame is detected by the door position sensor
Implementation Method 2
The sensor may be a reed switch or a Hall Effect sensor
Implementation Method 3
a permanent magnet mounted to the door and disposed in proximity to the sensor when the door is in a closed position
Implementation Method 4
an electromagnet and a strike plate. The electromagnet is secured to the door frame and the strike plate is movably mounted to the door
Implementation Method 5
When the electromagnet is energized and is in contact with the strike plate, the strike plate becomes an armature for the electromagnet, thus providing a mechanism for locking the door to the frame
Data Source
AI summary
A door position sensor of an electromagnetic door lock. The electromagnetic lock also includes an electromagnet and a strike plate. The electromagnet is secured to the door frame and the strike plate is movably mounted to the door so that a controlled amount of door movement in the opening direction is permitted while the strike plate remains in contact with an energized electromagnet. The door position sensor may comprise a sensor in or on the electromagnet and a permanent magnet mounted to the door and disposed in proximity to the sensor when the door is in a closed position. The sensor may be a reed switch or a Hall Effect sensor. The permanent magnet and strike plate may be mounted to the door by a mounting tray. The mounting tray may include indicia to aid in providing a proper alignment of the strike plate to the door and electromagnet.